From 1384c96f1912850b483744ab6dda63de0a665f26 Mon Sep 17 00:00:00 2001 From: Chet Ramey Date: Wed, 7 Dec 2011 09:02:33 -0500 Subject: [PATCH] commit bash-20070111 snapshot --- CWRU/CWRU.chlog | 96 + CWRU/CWRU.chlog~ | 100 +- array.c | 40 +- array.c~ | 960 ++ array.h | 1 + array.h~ | 111 + braces.c~ | 2 +- command.h | 1 + doc/FAQ | 4 +- doc/FAQ~ | 1841 ++++ doc/Makefile.tmp | 294 + doc/b.html | 15448 +++++++++++++++++++++++++++++++ doc/bash.1 | 37 +- doc/bash.1.orig | 776 +- doc/bash.1~ | 40 +- doc/bash.html | 2 +- doc/bashref.html | 415 +- doc/bashref.texi | 33 +- doc/bashref.texi.save | 7490 +++++++++++++++ doc/bashref.texi~ | 35 +- doc/faq.headers.mail | 6 +- doc/faq.mail | 6 +- doc/foo.html | 10220 ++++++++++++++++++++ doc/version.texi | 8 +- doc/version.texi~ | 4 +- execute_cmd.c | 5 + lib/readline/doc/hsuser.texi | 13 +- lib/readline/doc/hsuser.texi~ | 13 +- lib/readline/doc/version.texi | 8 +- lib/readline/doc/version.texi~ | 6 +- lib/readline/histfile.c | 4 +- lib/readline/histfile.c~ | 2 +- pcomplete.c | 5 +- subst.c | 124 +- subst.c.save1 | 8186 ++++++++++++++++ subst.c~ | 122 +- subst.h | 3 +- support/texi2html | 2 +- support/texi2html.debug | 5439 +++++++++++ variables.c | 3 +- variables.c~ | 23 +- 41 files changed, 51388 insertions(+), 540 deletions(-) create mode 100644 array.c~ create mode 100644 array.h~ create mode 100644 doc/FAQ~ create mode 100644 doc/Makefile.tmp create mode 100644 doc/b.html create mode 100644 doc/bashref.texi.save create mode 100644 doc/foo.html create mode 100644 subst.c.save1 create mode 100755 support/texi2html.debug diff --git a/CWRU/CWRU.chlog b/CWRU/CWRU.chlog index 2f4cd02d9..18ce7ee1a 100644 --- a/CWRU/CWRU.chlog +++ b/CWRU/CWRU.chlog @@ -14183,3 +14183,99 @@ lib/intl/Makefile.in lib/builtins/Makefile - fixes to build LIBINTL_H if necessary, dependency on this for mkbuiltins.o prevented `make -j 6' from working correctly + + 1/8 + --- +subst.c + - new function, fifos_pending(), returns the count of FIFOs in + fifo_list (process substitution) + +subst.h + - extern declaration for fifos_pending() + +execute_cmd.c + - in execute_simple_command, if CMD_NO_FORK is set before we call + execute_disk_command, make sure there are no FIFOs in the expanded + words (from process substitution) and turn off CMD_NO_FORK if there + are, so they can get unlinked when the command finishes + + 1/10 + ---- +subst.c + - read_comsub now takes a flags parameter and returns appropriate W_* + flags in it + - command_substitute now returns a WORD_DESC *, with the string it used + to return as the `word' and `flags' filled in appropriately + +subst.h + - changed extern declaration for command_substitute + +{pcomplete,subst}.c + - changed callers of command_substitute appropriately + +subst.c + - string_extract_verbatim now takes an additional int flags argument; + changed callers + + 1/11 + ---- +support/texi2html + - fix problem that caused index links to not be generated if the first + index node had a name different than the node name + +doc/bashref.texi + - encapsulated all indexes into a single `Indexes' appendix; works + around bug fixed in texi2html + + 1/12 + ---- +subst.c + - add call to sv_histtimefmt in initialize_variables so HISTTIMEFORMAT + rom the environment is honored. Fix from Ark Submedes (heh) + + +lib/readline/histfile.c + - make sure that the first character following the history comment + character at the beginning of a line is a digit before interpreting + it as a timestamp for the previous line + +doc/{bash.1,bashref.texi},lib/readline/doc/hsuser.texi + - added detail to make it clear exactly how history timestamps are + saved to and read from the history file + +subst.c + - change quote_escapes to add CTLESC before spaces if IFS is null, + just in case we have to split on literal spaces later on (e.g., in + case of unquoted $@). Corresponding changes to dequote_escapes. + Fixes a couple of problems reported by Brett Stahlman + + + 1/14 + ---- +subst.c + - make same change to read_comsub to add CTLESC before ' ' if $IFS is + null, since we will split on literal spaces later + + 1/15 + ---- +array.c + - new function, array_quote_escapes (ARRAY *a), calls quote_escapes + on each element of the array in the same way array_quote calls + quote_string + - call array_quote_escapes if match is not quoted in array_patsub + - array_slice is now used, so remove the #ifdef INCLUDE_UNUSED define + - change structure of array_subrange to call array_slice to create a + new array with the desired subset of elements, then call array_quote + or array_quote_escapes as necessary, like array_patsub. Convert to + a string by calling array_to_string on the sliced-out array + +array.h + - new extern declaration for array_quote_escapes + +subst.c + - since array_patsub now calls quote_escapes as necessary, callers + don't need to call it after array_patsub returns. Fixes first bug + reported by Brett Stahlman + - since array_subrange now calls quote_escapes as necessary, callers + don't need to call it after array_patsub returns. Same fix as + for array_patsub diff --git a/CWRU/CWRU.chlog~ b/CWRU/CWRU.chlog~ index 1d331b89e..b7cbfeafe 100644 --- a/CWRU/CWRU.chlog~ +++ b/CWRU/CWRU.chlog~ @@ -14171,5 +14171,103 @@ doc/{bash.1,bashref.texi},lib/readline/doc/rluser.texi [many files] - changes to make variables and function parameters `const' for better - text sharing + text sharing. Changes originally from Andreas Mohr + + 1/4/2007 + -------- +lib/intl/Makefile.in + - use cmp before copying libgnuintl.h to libintl.h -- maybe save a few + rebuilds + +lib/builtins/Makefile + - fixes to build LIBINTL_H if necessary, dependency on this for + mkbuiltins.o prevented `make -j 6' from working correctly + + 1/8 + --- +subst.c + - new function, fifos_pending(), returns the count of FIFOs in + fifo_list (process substitution) + +subst.h + - extern declaration for fifos_pending() + +execute_cmd.c + - in execute_simple_command, if CMD_NO_FORK is set before we call + execute_disk_command, make sure there are no FIFOs in the expanded + words (from process substitution) and turn off CMD_NO_FORK if there + are, so they can get unlinked when the command finishes + + 1/10 + ---- +subst.c + - read_comsub now takes a flags parameter and returns appropriate W_* + flags in it + - command_substitute now returns a WORD_DESC *, with the string it used + to return as the `word' and `flags' filled in appropriately + +subst.h + - changed extern declaration for command_substitute + +{pcomplete,subst}.c + - changed callers of command_substitute appropriately + +subst.c + - string_extract_verbatim now takes an additional int flags argument; + changed callers + + 1/11 + ---- +support/texi2html + - fix problem that caused index links to not be generated if the first + index node had a name different than the node name + +doc/bashref.texi + - encapsulated all indexes into a single `Indexes' appendix; works + around bug fixed in texi2html + + 1/12 + ---- +subst.c + - add call to sv_histtimefmt in initialize_variables so HISTTIMEFORMAT + rom the environment is honored. Fix from Ark Submedes (heh) + + +lib/readline/histfile.c + - make sure that the first character following the history comment + character at the beginning of a line is a digit before interpreting + it as a timestamp for the previous line + +doc/{bash.1,bashref.texi},lib/readline/doc/hsuser.texi + - added detail to make it clear exactly how history timestamps are + saved to and read from the history file + +subst.c + - change quote_escapes to add CTLESC before spaces if IFS is null, + just in case we have to split on literal spaces later on (e.g., in + case of unquoted $@). Corresponding changes to dequote_escapes. + Fixes a couple of problems reported by Brett Stahlman + + + 1/14 + ---- +subst.c + - make same change to read_comsub to add CTLESC before ' ' if $IFS is + null, since we will split on literal spaces later + + 1/15 + ---- +array.c + - new function, array_quote_escapes (ARRAY *a), calls quote_escapes + on each element of the array in the same way array_quote calls + quote_string + - call array_quote_escapes if match is not quoted in array_patsub + +array.h + - new extern declaration for array_quote_escapes + +subst.c + - since array_patsub now calls quote_escapes as necessary, callers + don't need to call it after array_patsub returns. Fixes first bug + reported by Brett Stahlman diff --git a/array.c b/array.c index c32b61344..4cfa51169 100644 --- a/array.c +++ b/array.c @@ -120,7 +120,6 @@ ARRAY *a; return(a1); } -#ifdef INCLUDE_UNUSED /* * Make and return a new array composed of the elements in array A from * S to E, inclusive. @@ -141,13 +140,12 @@ ARRAY_ELEMENT *s, *e; for (p = s, i = 0; p != e; p = element_forw(p), i++) { n = array_create_element (element_index(p), element_value(p)); ADD_BEFORE(a->head, n); - mi = element_index(ae); + mi = element_index(n); } a->num_elements = i; a->max_index = mi; return a; } -#endif /* * Walk the array, calling FUNC once for each element, with the array @@ -300,6 +298,23 @@ ARRAY *array; return array; } +ARRAY * +array_quote_escapes(array) +ARRAY *array; +{ + ARRAY_ELEMENT *a; + char *t; + + if (array == 0 || array_head(array) == 0 || array_empty(array)) + return (ARRAY *)NULL; + for (a = element_forw(array->head); a != array->head; a = element_forw(a)) { + t = quote_escapes (a->value); + FREE(a->value); + a->value = t; + } + return array; +} + /* * Return a string whose elements are the members of array A beginning at * index START and spanning NELEM members. Null elements are counted. @@ -311,9 +326,10 @@ ARRAY *a; arrayind_t start, nelem; int starsub, quoted; { + ARRAY *a2; ARRAY_ELEMENT *h, *p; arrayind_t i; - char *ifs, sep[2]; + char *ifs, sep[2], *t; p = a ? array_head (a) : 0; if (p == 0 || array_empty (a) || start > array_max_index(a)) @@ -336,6 +352,13 @@ int starsub, quoted; for (i = 0, h = p; p != a->head && i < nelem; i++, p = element_forw(p)) ; + a2 = array_slice(a, h, p); + + if (quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT)) + array_quote(a2); + else + array_quote_escapes(a2); + if (starsub && (quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT))) { ifs = getifs(); sep[0] = ifs ? *ifs : '\0'; @@ -343,7 +366,10 @@ int starsub, quoted; sep[0] = ' '; sep[1] = '\0'; - return (array_to_string_internal (h, p, sep, quoted)); + t = array_to_string (a2, sep, 0); + array_dispose(a2); + + return t; } char * @@ -367,7 +393,9 @@ int mflags; } if (mflags & MATCH_QUOTED) - array_quote (a2); + array_quote(a2); + else + array_quote_escapes(a2); if (mflags & MATCH_STARSUB) { ifs = getifs(); sifs[0] = ifs ? *ifs : '\0'; diff --git a/array.c~ b/array.c~ new file mode 100644 index 000000000..f3ed08bb9 --- /dev/null +++ b/array.c~ @@ -0,0 +1,960 @@ +/* + * array.c - functions to create, destroy, access, and manipulate arrays + * of strings. + * + * Arrays are sparse doubly-linked lists. An element's index is stored + * with it. + * + * Chet Ramey + * chet@ins.cwru.edu + */ + +/* Copyright (C) 1997-2004 Free Software Foundation, Inc. + + This file is part of GNU Bash, the Bourne Again SHell. + + Bash is free software; you can redistribute it and/or modify it under + the terms of the GNU General Public License as published by the Free + Software Foundation; either version 2, or (at your option) any later + version. + + Bash is distributed in the hope that it will be useful, but WITHOUT ANY + WARRANTY; without even the implied warranty of MERCHANTABILITY or + FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + for more details. + + You should have received a copy of the GNU General Public License along + with Bash; see the file COPYING. If not, write to the Free Software + Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA. */ + +#include "config.h" + +#if defined (ARRAY_VARS) + +#if defined (HAVE_UNISTD_H) +# ifdef _MINIX +# include +# endif +# include +#endif + +#include +#include "bashansi.h" + +#include "shell.h" +#include "array.h" +#include "builtins/common.h" + +#define ADD_BEFORE(ae, new) \ + do { \ + ae->prev->next = new; \ + new->prev = ae->prev; \ + ae->prev = new; \ + new->next = ae; \ + } while(0) + +static char *array_to_string_internal __P((ARRAY_ELEMENT *, ARRAY_ELEMENT *, char *, int)); + +ARRAY * +array_create() +{ + ARRAY *r; + ARRAY_ELEMENT *head; + + r =(ARRAY *)xmalloc(sizeof(ARRAY)); + r->type = array_indexed; + r->max_index = -1; + r->num_elements = 0; + head = array_create_element(-1, (char *)NULL); /* dummy head */ + head->prev = head->next = head; + r->head = head; + return(r); +} + +void +array_flush (a) +ARRAY *a; +{ + register ARRAY_ELEMENT *r, *r1; + + if (a == 0) + return; + for (r = element_forw(a->head); r != a->head; ) { + r1 = element_forw(r); + array_dispose_element(r); + r = r1; + } + a->head->next = a->head->prev = a->head; + a->max_index = -1; + a->num_elements = 0; +} + +void +array_dispose(a) +ARRAY *a; +{ + if (a == 0) + return; + array_flush (a); + array_dispose_element(a->head); + free(a); +} + +ARRAY * +array_copy(a) +ARRAY *a; +{ + ARRAY *a1; + ARRAY_ELEMENT *ae, *new; + + if (a == 0) + return((ARRAY *) NULL); + a1 = array_create(); + a1->type = a->type; + a1->max_index = a->max_index; + a1->num_elements = a->num_elements; + for (ae = element_forw(a->head); ae != a->head; ae = element_forw(ae)) { + new = array_create_element(element_index(ae), element_value(ae)); + ADD_BEFORE(a1->head, new); + } + return(a1); +} + +/* + * Make and return a new array composed of the elements in array A from + * S to E, inclusive. + */ +ARRAY * +array_slice(array, s, e) +ARRAY *array; +ARRAY_ELEMENT *s, *e; +{ + ARRAY *a; + ARRAY_ELEMENT *p, *n; + int i; + arrayind_t mi; + + a = array_create (); + a->type = array->type; + + for (p = s, i = 0; p != e; p = element_forw(p), i++) { + n = array_create_element (element_index(p), element_value(p)); + ADD_BEFORE(a->head, n); + mi = element_index(n); + } + a->num_elements = i; + a->max_index = mi; + return a; +} + +/* + * Walk the array, calling FUNC once for each element, with the array + * element as the argument. + */ +void +array_walk(a, func, udata) +ARRAY *a; +sh_ae_map_func_t *func; +void *udata; +{ + register ARRAY_ELEMENT *ae; + + if (a == 0 || array_empty(a)) + return; + for (ae = element_forw(a->head); ae != a->head; ae = element_forw(ae)) + if ((*func)(ae, udata) < 0) + return; +} + +/* + * Shift the array A N elements to the left. Delete the first N elements + * and subtract N from the indices of the remaining elements. If FLAGS + * does not include AS_DISPOSE, this returns a singly-linked null-terminated + * list of elements so the caller can dispose of the chain. If FLAGS + * includes AS_DISPOSE, this function disposes of the shifted-out elements + * and returns NULL. + */ +ARRAY_ELEMENT * +array_shift(a, n, flags) +ARRAY *a; +int n, flags; +{ + register ARRAY_ELEMENT *ae, *ret; + register int i; + + if (a == 0 || array_empty(a) || n <= 0) + return ((ARRAY_ELEMENT *)NULL); + + for (i = 0, ret = ae = element_forw(a->head); ae != a->head && i < n; ae = element_forw(ae), i++) + ; + if (ae == a->head) { + /* Easy case; shifting out all of the elements */ + if (flags & AS_DISPOSE) { + array_flush (a); + return ((ARRAY_ELEMENT *)NULL); + } + for (ae = ret; element_forw(ae) != a->head; ae = element_forw(ae)) + ; + element_forw(ae) = (ARRAY_ELEMENT *)NULL; + a->head->next = a->head->prev = a->head; + a->max_index = -1; + a->num_elements = 0; + return ret; + } + /* + * ae now points to the list of elements we want to retain. + * ret points to the list we want to either destroy or return. + */ + ae->prev->next = (ARRAY_ELEMENT *)NULL; /* null-terminate RET */ + + a->head->next = ae; /* slice RET out of the array */ + ae->prev = a->head; + + for ( ; ae != a->head; ae = element_forw(ae)) + element_index(ae) -= n; /* renumber retained indices */ + + a->num_elements -= n; /* modify bookkeeping information */ + a->max_index -= n; + + if (flags & AS_DISPOSE) { + for (ae = ret; ae; ) { + ret = element_forw(ae); + array_dispose_element(ae); + ae = ret; + } + return ((ARRAY_ELEMENT *)NULL); + } + + return ret; +} + +/* + * Shift array A right N indices. If S is non-null, it becomes the value of + * the new element 0. Returns the number of elements in the array after the + * shift. + */ +int +array_rshift (a, n, s) +ARRAY *a; +int n; +char *s; +{ + register ARRAY_ELEMENT *ae, *new; + + if (a == 0 || (array_empty(a) && s == 0)) + return 0; + else if (n <= 0) + return (a->num_elements); + + ae = element_forw(a->head); + if (s) { + new = array_create_element(0, s); + ADD_BEFORE(ae, new); + a->num_elements++; + if (array_num_elements(a) == 1) /* array was empty */ + return 1; + } + + /* + * Renumber all elements in the array except the one we just added. + */ + for ( ; ae != a->head; ae = element_forw(ae)) + element_index(ae) += n; + + a->max_index = element_index(a->head->prev); + + return (a->num_elements); +} + +ARRAY_ELEMENT * +array_unshift_element(a) +ARRAY *a; +{ + return (array_shift (a, 1, 0)); +} + +int +array_shift_element(a, v) +ARRAY *a; +char *v; +{ + return (array_rshift (a, 1, v)); +} + +ARRAY * +array_quote(array) +ARRAY *array; +{ + ARRAY_ELEMENT *a; + char *t; + + if (array == 0 || array_head(array) == 0 || array_empty(array)) + return (ARRAY *)NULL; + for (a = element_forw(array->head); a != array->head; a = element_forw(a)) { + t = quote_string (a->value); + FREE(a->value); + a->value = t; + } + return array; +} + +ARRAY * +array_quote_escapes(array) +ARRAY *array; +{ + ARRAY_ELEMENT *a; + char *t; + + if (array == 0 || array_head(array) == 0 || array_empty(array)) + return (ARRAY *)NULL; + for (a = element_forw(array->head); a != array->head; a = element_forw(a)) { + t = quote_escapes (a->value); + FREE(a->value); + a->value = t; + } + return array; +} + +/* + * Return a string whose elements are the members of array A beginning at + * index START and spanning NELEM members. Null elements are counted. + * Since arrays are sparse, unset array elements are not counted. + */ +char * +array_subrange (a, start, nelem, starsub, quoted) +ARRAY *a; +arrayind_t start, nelem; +int starsub, quoted; +{ + ARRAY *a2; + ARRAY_ELEMENT *h, *p; + arrayind_t i; + char *ifs, sep[2], *t; + + p = a ? array_head (a) : 0; + if (p == 0 || array_empty (a) || start > array_max_index(a)) + return ((char *)NULL); + + /* + * Find element with index START. If START corresponds to an unset + * element (arrays can be sparse), use the first element whose index + * is >= START. If START is < 0, we count START indices back from + * the end of A (not elements, even with sparse arrays -- START is an + * index). + */ + for (p = element_forw(p); p != array_head(a) && start > element_index(p); p = element_forw(p)) + ; + + if (p == a->head) + return ((char *)NULL); + + /* Starting at P, take NELEM elements, inclusive. */ + for (i = 0, h = p; p != a->head && i < nelem; i++, p = element_forw(p)) + ; + + a2 = array_slice(a, h, p); + + if (mflags & MATCH_QUOTED) + array_quote (a2); + else + array_quote_escapes (a2); + + if (starsub && (quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT))) { + ifs = getifs(); + sep[0] = ifs ? *ifs : '\0'; + } else + sep[0] = ' '; + sep[1] = '\0'; + + t = array_to_string (a2, sep, 0); + array_dispose(a2); + + return t; +} + +char * +array_patsub (a, pat, rep, mflags) +ARRAY *a; +char *pat, *rep; +int mflags; +{ + ARRAY *a2; + ARRAY_ELEMENT *e; + char *t, *ifs, sifs[2]; + + if (a == 0 || array_head(a) == 0 || array_empty(a)) + return ((char *)NULL); + + a2 = array_copy(a); + for (e = element_forw(a2->head); e != a2->head; e = element_forw(e)) { + t = pat_subst(element_value(e), pat, rep, mflags); + FREE(element_value(e)); + e->value = t; + } + + if (mflags & MATCH_QUOTED) + array_quote (a2); + else + array_quote_escapes (a2); + if (mflags & MATCH_STARSUB) { + ifs = getifs(); + sifs[0] = ifs ? *ifs : '\0'; + sifs[1] = '\0'; + t = array_to_string (a2, sifs, 0); + } else + t = array_to_string (a2, " ", 0); + array_dispose (a2); + + return t; +} + +/* + * Allocate and return a new array element with index INDEX and value + * VALUE. + */ +ARRAY_ELEMENT * +array_create_element(indx, value) +arrayind_t indx; +char *value; +{ + ARRAY_ELEMENT *r; + + r = (ARRAY_ELEMENT *)xmalloc(sizeof(ARRAY_ELEMENT)); + r->ind = indx; + r->value = value ? savestring(value) : (char *)NULL; + r->next = r->prev = (ARRAY_ELEMENT *) NULL; + return(r); +} + +#ifdef INCLUDE_UNUSED +ARRAY_ELEMENT * +array_copy_element(ae) +ARRAY_ELEMENT *ae; +{ + return(ae ? array_create_element(element_index(ae), element_value(ae)) + : (ARRAY_ELEMENT *) NULL); +} +#endif + +void +array_dispose_element(ae) +ARRAY_ELEMENT *ae; +{ + if (ae) { + FREE(ae->value); + free(ae); + } +} + +/* + * Add a new element with index I and value V to array A (a[i] = v). + */ +int +array_insert(a, i, v) +ARRAY *a; +arrayind_t i; +char *v; +{ + register ARRAY_ELEMENT *new, *ae; + + if (a == 0) + return(-1); + new = array_create_element(i, v); + if (i > array_max_index(a)) { + /* + * Hook onto the end. This also works for an empty array. + * Fast path for the common case of allocating arrays + * sequentially. + */ + ADD_BEFORE(a->head, new); + a->max_index = i; + a->num_elements++; + return(0); + } + /* + * Otherwise we search for the spot to insert it. + */ + for (ae = element_forw(a->head); ae != a->head; ae = element_forw(ae)) { + if (element_index(ae) == i) { + /* + * Replacing an existing element. + */ + array_dispose_element(new); + free(element_value(ae)); + ae->value = v ? savestring(v) : (char *)NULL; + return(0); + } else if (element_index(ae) > i) { + ADD_BEFORE(ae, new); + a->num_elements++; + return(0); + } + } + return (-1); /* problem */ +} + +/* + * Delete the element with index I from array A and return it so the + * caller can dispose of it. + */ +ARRAY_ELEMENT * +array_remove(a, i) +ARRAY *a; +arrayind_t i; +{ + register ARRAY_ELEMENT *ae; + + if (a == 0 || array_empty(a)) + return((ARRAY_ELEMENT *) NULL); + for (ae = element_forw(a->head); ae != a->head; ae = element_forw(ae)) + if (element_index(ae) == i) { + ae->next->prev = ae->prev; + ae->prev->next = ae->next; + a->num_elements--; + if (i == array_max_index(a)) + a->max_index = element_index(ae->prev); + return(ae); + } + return((ARRAY_ELEMENT *) NULL); +} + +/* + * Return the value of a[i]. + */ +char * +array_reference(a, i) +ARRAY *a; +arrayind_t i; +{ + register ARRAY_ELEMENT *ae; + + if (a == 0 || array_empty(a)) + return((char *) NULL); + for (ae = element_forw(a->head); ae != a->head; ae = element_forw(ae)) + if (element_index(ae) == i) + return(element_value(ae)); + return((char *) NULL); +} + +/* Convenience routines for the shell to translate to and from the form used + by the rest of the code. */ + +WORD_LIST * +array_to_word_list(a) +ARRAY *a; +{ + WORD_LIST *list; + ARRAY_ELEMENT *ae; + + if (a == 0 || array_empty(a)) + return((WORD_LIST *)NULL); + list = (WORD_LIST *)NULL; + for (ae = element_forw(a->head); ae != a->head; ae = element_forw(ae)) + list = make_word_list (make_bare_word(element_value(ae)), list); + return (REVERSE_LIST(list, WORD_LIST *)); +} + +ARRAY * +array_from_word_list (list) +WORD_LIST *list; +{ + ARRAY *a; + + if (list == 0) + return((ARRAY *)NULL); + a = array_create(); + return (array_assign_list (a, list)); +} + +WORD_LIST * +array_keys_to_word_list(a) +ARRAY *a; +{ + WORD_LIST *list; + ARRAY_ELEMENT *ae; + char *t; + + if (a == 0 || array_empty(a)) + return((WORD_LIST *)NULL); + list = (WORD_LIST *)NULL; + for (ae = element_forw(a->head); ae != a->head; ae = element_forw(ae)) { + t = itos(element_index(ae)); + list = make_word_list (make_bare_word(t), list); + free(t); + } + return (REVERSE_LIST(list, WORD_LIST *)); +} + +ARRAY * +array_assign_list (array, list) +ARRAY *array; +WORD_LIST *list; +{ + register WORD_LIST *l; + register arrayind_t i; + + for (l = list, i = 0; l; l = l->next, i++) + array_insert(array, i, l->word->word); + return array; +} + +char ** +array_to_argv (a) +ARRAY *a; +{ + char **ret, *t; + int i; + ARRAY_ELEMENT *ae; + + if (a == 0 || array_empty(a)) + return ((char **)NULL); + ret = strvec_create (array_num_elements (a) + 1); + i = 0; + for (ae = element_forw(a->head); ae != a->head; ae = element_forw(ae)) { + t = element_value (ae); + ret[i++] = t ? savestring (t) : (char *)NULL; + } + ret[i] = (char *)NULL; + return (ret); +} + +/* + * Return a string that is the concatenation of all the elements in A, + * separated by SEP. + */ +static char * +array_to_string_internal (start, end, sep, quoted) +ARRAY_ELEMENT *start, *end; +char *sep; +int quoted; +{ + char *result, *t; + ARRAY_ELEMENT *ae; + int slen, rsize, rlen, reg; + + if (start == end) /* XXX - should not happen */ + return ((char *)NULL); + + slen = strlen(sep); + result = NULL; + for (rsize = rlen = 0, ae = start; ae != end; ae = element_forw(ae)) { + if (rsize == 0) + result = (char *)xmalloc (rsize = 64); + if (element_value(ae)) { + t = quoted ? quote_string(element_value(ae)) : element_value(ae); + reg = strlen(t); + RESIZE_MALLOCED_BUFFER (result, rlen, (reg + slen + 2), + rsize, rsize); + strcpy(result + rlen, t); + rlen += reg; + if (quoted && t) + free(t); + /* + * Add a separator only after non-null elements. + */ + if (element_forw(ae) != end) { + strcpy(result + rlen, sep); + rlen += slen; + } + } + } + if (result) + result[rlen] = '\0'; /* XXX */ + return(result); +} + +char * +array_to_assign (a, quoted) +ARRAY *a; +int quoted; +{ + char *result, *valstr, *is; + char indstr[INT_STRLEN_BOUND(intmax_t) + 1]; + ARRAY_ELEMENT *ae; + int rsize, rlen, elen; + + if (a == 0 || array_empty (a)) + return((char *)NULL); + + result = (char *)xmalloc (rsize = 128); + result[0] = '('; + rlen = 1; + + for (ae = element_forw(a->head); ae != a->head; ae = element_forw(ae)) { + is = inttostr (element_index(ae), indstr, sizeof(indstr)); + valstr = element_value (ae) ? sh_double_quote (element_value(ae)) + : (char *)NULL; + elen = STRLEN (indstr) + 8 + STRLEN (valstr); + RESIZE_MALLOCED_BUFFER (result, rlen, (elen + 1), rsize, rsize); + + result[rlen++] = '['; + strcpy (result + rlen, is); + rlen += STRLEN (is); + result[rlen++] = ']'; + result[rlen++] = '='; + if (valstr) { + strcpy (result + rlen, valstr); + rlen += STRLEN (valstr); + } + + if (element_forw(ae) != a->head) + result[rlen++] = ' '; + + FREE (valstr); + } + RESIZE_MALLOCED_BUFFER (result, rlen, 1, rsize, 8); + result[rlen++] = ')'; + result[rlen] = '\0'; + if (quoted) { + /* This is not as efficient as it could be... */ + valstr = sh_single_quote (result); + free (result); + result = valstr; + } + return(result); +} + +char * +array_to_string (a, sep, quoted) +ARRAY *a; +char *sep; +int quoted; +{ + if (a == 0) + return((char *)NULL); + if (array_empty(a)) + return(savestring("")); + return (array_to_string_internal (element_forw(a->head), a->head, sep, quoted)); +} + +#if defined (INCLUDE_UNUSED) || defined (TEST_ARRAY) +/* + * Return an array consisting of elements in S, separated by SEP + */ +ARRAY * +array_from_string(s, sep) +char *s, *sep; +{ + ARRAY *a; + WORD_LIST *w; + + if (s == 0) + return((ARRAY *)NULL); + w = list_string (s, sep, 0); + if (w == 0) + return((ARRAY *)NULL); + a = array_from_word_list (w); + return (a); +} +#endif + +#if defined (TEST_ARRAY) +/* + * To make a running version, compile -DTEST_ARRAY and link with: + * xmalloc.o syntax.o lib/malloc/libmalloc.a lib/sh/libsh.a + */ +int interrupt_immediately = 0; + +int +signal_is_trapped(s) +int s; +{ + return 0; +} + +void +fatal_error(const char *s, ...) +{ + fprintf(stderr, "array_test: fatal memory error\n"); + abort(); +} + +void +programming_error(const char *s, ...) +{ + fprintf(stderr, "array_test: fatal programming error\n"); + abort(); +} + +WORD_DESC * +make_bare_word (s) +const char *s; +{ + WORD_DESC *w; + + w = (WORD_DESC *)xmalloc(sizeof(WORD_DESC)); + w->word = s ? savestring(s) : savestring (""); + w->flags = 0; + return w; +} + +WORD_LIST * +make_word_list(x, l) +WORD_DESC *x; +WORD_LIST *l; +{ + WORD_LIST *w; + + w = (WORD_LIST *)xmalloc(sizeof(WORD_LIST)); + w->word = x; + w->next = l; + return w; +} + +WORD_LIST * +list_string(s, t, i) +char *s, *t; +int i; +{ + char *r, *a; + WORD_LIST *wl; + + if (s == 0) + return (WORD_LIST *)NULL; + r = savestring(s); + wl = (WORD_LIST *)NULL; + a = strtok(r, t); + while (a) { + wl = make_word_list (make_bare_word(a), wl); + a = strtok((char *)NULL, t); + } + return (REVERSE_LIST (wl, WORD_LIST *)); +} + +GENERIC_LIST * +list_reverse (list) +GENERIC_LIST *list; +{ + register GENERIC_LIST *next, *prev; + + for (prev = 0; list; ) { + next = list->next; + list->next = prev; + prev = list; + list = next; + } + return prev; +} + +char * +pat_subst(s, t, u, i) +char *s, *t, *u; +int i; +{ + return ((char *)NULL); +} + +char * +quote_string(s) +char *s; +{ + return savestring(s); +} + +print_element(ae) +ARRAY_ELEMENT *ae; +{ + char lbuf[INT_STRLEN_BOUND (intmax_t) + 1]; + + printf("array[%s] = %s\n", + inttostr (element_index(ae), lbuf, sizeof (lbuf)), + element_value(ae)); +} + +print_array(a) +ARRAY *a; +{ + printf("\n"); + array_walk(a, print_element, (void *)NULL); +} + +main() +{ + ARRAY *a, *new_a, *copy_of_a; + ARRAY_ELEMENT *ae, *aew; + char *s; + + a = array_create(); + array_insert(a, 1, "one"); + array_insert(a, 7, "seven"); + array_insert(a, 4, "four"); + array_insert(a, 1029, "one thousand twenty-nine"); + array_insert(a, 12, "twelve"); + array_insert(a, 42, "forty-two"); + print_array(a); + s = array_to_string (a, " ", 0); + printf("s = %s\n", s); + copy_of_a = array_from_string(s, " "); + printf("copy_of_a:"); + print_array(copy_of_a); + array_dispose(copy_of_a); + printf("\n"); + free(s); + ae = array_remove(a, 4); + array_dispose_element(ae); + ae = array_remove(a, 1029); + array_dispose_element(ae); + array_insert(a, 16, "sixteen"); + print_array(a); + s = array_to_string (a, " ", 0); + printf("s = %s\n", s); + copy_of_a = array_from_string(s, " "); + printf("copy_of_a:"); + print_array(copy_of_a); + array_dispose(copy_of_a); + printf("\n"); + free(s); + array_insert(a, 2, "two"); + array_insert(a, 1029, "new one thousand twenty-nine"); + array_insert(a, 0, "zero"); + array_insert(a, 134, ""); + print_array(a); + s = array_to_string (a, ":", 0); + printf("s = %s\n", s); + copy_of_a = array_from_string(s, ":"); + printf("copy_of_a:"); + print_array(copy_of_a); + array_dispose(copy_of_a); + printf("\n"); + free(s); + new_a = array_copy(a); + print_array(new_a); + s = array_to_string (new_a, ":", 0); + printf("s = %s\n", s); + copy_of_a = array_from_string(s, ":"); + free(s); + printf("copy_of_a:"); + print_array(copy_of_a); + array_shift(copy_of_a, 2, AS_DISPOSE); + printf("copy_of_a shifted by two:"); + print_array(copy_of_a); + ae = array_shift(copy_of_a, 2, 0); + printf("copy_of_a shifted by two:"); + print_array(copy_of_a); + for ( ; ae; ) { + aew = element_forw(ae); + array_dispose_element(ae); + ae = aew; + } + array_rshift(copy_of_a, 1, (char *)0); + printf("copy_of_a rshift by 1:"); + print_array(copy_of_a); + array_rshift(copy_of_a, 2, "new element zero"); + printf("copy_of_a rshift again by 2 with new element zero:"); + print_array(copy_of_a); + s = array_to_assign(copy_of_a, 0); + printf("copy_of_a=%s\n", s); + free(s); + ae = array_shift(copy_of_a, array_num_elements(copy_of_a), 0); + for ( ; ae; ) { + aew = element_forw(ae); + array_dispose_element(ae); + ae = aew; + } + array_dispose(copy_of_a); + printf("\n"); + array_dispose(a); + array_dispose(new_a); +} + +#endif /* TEST_ARRAY */ +#endif /* ARRAY_VARS */ diff --git a/array.h b/array.h index 8c671b79e..b9632b42e 100644 --- a/array.h +++ b/array.h @@ -55,6 +55,7 @@ extern int array_rshift __P((ARRAY *, int, char *)); extern ARRAY_ELEMENT *array_unshift_element __P((ARRAY *)); extern int array_shift_element __P((ARRAY *, char *)); extern ARRAY *array_quote __P((ARRAY *)); +extern ARRAY *array_quote_escapes __P((ARRAY *)); extern char *array_subrange __P((ARRAY *, arrayind_t, arrayind_t, int, int)); extern char *array_patsub __P((ARRAY *, char *, char *, int)); diff --git a/array.h~ b/array.h~ new file mode 100644 index 000000000..8c671b79e --- /dev/null +++ b/array.h~ @@ -0,0 +1,111 @@ +/* array.h -- definitions for the interface exported by array.c that allows + the rest of the shell to manipulate array variables. */ + +/* Copyright (C) 1997 Free Software Foundation, Inc. + + This file is part of GNU Bash, the Bourne Again SHell. + + Bash is free software; you can redistribute it and/or modify it under + the terms of the GNU General Public License as published by the Free + Software Foundation; either version 2, or (at your option) any later + version. + + Bash is distributed in the hope that it will be useful, but WITHOUT ANY + WARRANTY; without even the implied warranty of MERCHANTABILITY or + FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + for more details. + + You should have received a copy of the GNU General Public License along + with Bash; see the file COPYING. If not, write to the Free Software + Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA. */ + +#ifndef _ARRAY_H_ +#define _ARRAY_H_ + +#include "stdc.h" + +typedef intmax_t arrayind_t; + +enum atype {array_indexed, array_assoc}; + +typedef struct array { + enum atype type; + arrayind_t max_index, num_elements; + struct array_element *head; +} ARRAY; + +typedef struct array_element { + arrayind_t ind; + char *value; + struct array_element *next, *prev; +} ARRAY_ELEMENT; + +typedef int sh_ae_map_func_t __P((ARRAY_ELEMENT *, void *)); + +/* Basic operations on entire arrays */ +extern ARRAY *array_create __P((void)); +extern void array_flush __P((ARRAY *)); +extern void array_dispose __P((ARRAY *)); +extern ARRAY *array_copy __P((ARRAY *)); +extern ARRAY *array_slice __P((ARRAY *, ARRAY_ELEMENT *, ARRAY_ELEMENT *)); +extern void array_walk __P((ARRAY *, sh_ae_map_func_t *, void *)); + +extern ARRAY_ELEMENT *array_shift __P((ARRAY *, int, int)); +extern int array_rshift __P((ARRAY *, int, char *)); +extern ARRAY_ELEMENT *array_unshift_element __P((ARRAY *)); +extern int array_shift_element __P((ARRAY *, char *)); +extern ARRAY *array_quote __P((ARRAY *)); + +extern char *array_subrange __P((ARRAY *, arrayind_t, arrayind_t, int, int)); +extern char *array_patsub __P((ARRAY *, char *, char *, int)); + +/* Basic operations on array elements. */ +extern ARRAY_ELEMENT *array_create_element __P((arrayind_t, char *)); +extern ARRAY_ELEMENT *array_copy_element __P((ARRAY_ELEMENT *)); +extern void array_dispose_element __P((ARRAY_ELEMENT *)); + +extern int array_insert __P((ARRAY *, arrayind_t, char *)); +extern ARRAY_ELEMENT *array_remove __P((ARRAY *, arrayind_t)); +extern char *array_reference __P((ARRAY *, arrayind_t)); + +/* Converting to and from arrays */ +extern WORD_LIST *array_to_word_list __P((ARRAY *)); +extern ARRAY *array_from_word_list __P((WORD_LIST *)); +extern WORD_LIST *array_keys_to_word_list __P((ARRAY *)); + +extern ARRAY *array_assign_list __P((ARRAY *, WORD_LIST *)); + +extern char **array_to_argv __P((ARRAY *)); + +extern char *array_to_assign __P((ARRAY *, int)); +extern char *array_to_string __P((ARRAY *, char *, int)); +extern ARRAY *array_from_string __P((char *, char *)); + +/* Flags for array_shift */ +#define AS_DISPOSE 0x01 + +#define array_num_elements(a) ((a)->num_elements) +#define array_max_index(a) ((a)->max_index) +#define array_head(a) ((a)->head) +#define array_empty(a) ((a)->num_elements == 0) + +#define element_value(ae) ((ae)->value) +#define element_index(ae) ((ae)->ind) +#define element_forw(ae) ((ae)->next) +#define element_back(ae) ((ae)->prev) + +/* Convenience */ +#define array_push(a,v) \ + do { array_rshift ((a), 1, (v)); } while (0) +#define array_pop(a) \ + do { array_dispose_element (array_shift ((a), 1, 0)); } while (0) + +#define GET_ARRAY_FROM_VAR(n, v, a) \ + do { \ + (v) = find_variable (n); \ + (a) = ((v) && array_p ((v))) ? array_cell (v) : (ARRAY *)0; \ + } while (0) + +#define ALL_ELEMENT_SUB(c) ((c) == '@' || (c) == '*') + +#endif /* _ARRAY_H_ */ diff --git a/braces.c~ b/braces.c~ index 253739741..34a72be43 100644 --- a/braces.c~ +++ b/braces.c~ @@ -55,7 +55,7 @@ */ /* The character which is used to separate arguments. */ -int brace_arg_separator = ','; +static const int brace_arg_separator = ','; #if defined (__P) static int brace_gobbler __P((char *, size_t, int *, int)); diff --git a/command.h b/command.h index 75e4990d0..37cfcb6c9 100644 --- a/command.h +++ b/command.h @@ -88,6 +88,7 @@ enum command_type { cm_for, cm_case, cm_while, cm_if, cm_simple, cm_select, #define W_HASQUOTEDNULL 0x040000 /* word contains a quoted null character */ #define W_DQUOTE 0x080000 /* word should be treated as if double-quoted */ #define W_NOPROCSUB 0x100000 /* don't perform process substitution */ +#define W_HASCTLESC 0x200000 /* word contains literal CTLESC characters */ /* Possible values for subshell_environment */ #define SUBSHELL_ASYNC 0x01 /* subshell caused by `command &' */ diff --git a/doc/FAQ b/doc/FAQ index 1d10b32b5..dd3ea566a 100644 --- a/doc/FAQ +++ b/doc/FAQ @@ -908,7 +908,9 @@ D1) Why does bash run a different version of `command' than On many systems, `which' is actually a csh script that assumes you're running csh. In tcsh, `which' and its cousin `where' are builtins. On other Unix systems, `which' is a perl script -that uses the PATH environment variable. +that uses the PATH environment variable. Many Linux distributions +use GNU `which', which is a C program that can understand shell +aliases. The csh script version reads the csh startup files from your home directory and uses those to determine which `command' will diff --git a/doc/FAQ~ b/doc/FAQ~ new file mode 100644 index 000000000..1d10b32b5 --- /dev/null +++ b/doc/FAQ~ @@ -0,0 +1,1841 @@ +This is the Bash FAQ, version 3.35, for Bash version 3.2. + +This document contains a set of frequently-asked questions concerning +Bash, the GNU Bourne-Again Shell. Bash is a freely-available command +interpreter with advanced features for both interactive use and shell +programming. + +Another good source of basic information about shells is the collection +of FAQ articles periodically posted to comp.unix.shell. + +Questions and comments concerning this document should be sent to +chet.ramey@case.edu. + +This document is available for anonymous FTP with the URL + +ftp://ftp.cwru.edu/pub/bash/FAQ + +The Bash home page is http://cnswww.cns.cwru.edu/~chet/bash/bashtop.html + +---------- +Contents: + +Section A: The Basics + +A1) What is it? +A2) What's the latest version? +A3) Where can I get it? +A4) On what machines will bash run? +A5) Will bash run on operating systems other than Unix? +A6) How can I build bash with gcc? +A7) How can I make bash my login shell? +A8) I just changed my login shell to bash, and now I can't FTP into my + machine. Why not? +A9) What's the `POSIX Shell and Utilities standard'? +A10) What is the bash `posix mode'? + +Section B: The latest version + +B1) What's new in version 3.2? +B2) Are there any user-visible incompatibilities between bash-3.2 and + bash-2.05b? + +Section C: Differences from other Unix shells + +C1) How does bash differ from sh, the Bourne shell? +C2) How does bash differ from the Korn shell, version ksh88? +C3) Which new features in ksh-93 are not in bash, and which are? + +Section D: Why does bash do some things differently than other Unix shells? + +D1) Why does bash run a different version of `command' than + `which command' says it will? +D2) Why doesn't bash treat brace expansions exactly like csh? +D3) Why doesn't bash have csh variable modifiers? +D4) How can I make my csh aliases work when I convert to bash? +D5) How can I pipe standard output and standard error from one command to + another, like csh does with `|&'? +D6) Now that I've converted from ksh to bash, are there equivalents to + ksh features like autoloaded functions and the `whence' command? + +Section E: Why does bash do certain things the way it does? + +E1) Why is the bash builtin `test' slightly different from /bin/test? +E2) Why does bash sometimes say `Broken pipe'? +E3) When I have terminal escape sequences in my prompt, why does bash + wrap lines at the wrong column? +E4) If I pipe the output of a command into `read variable', why doesn't + the output show up in $variable when the read command finishes? +E5) I have a bunch of shell scripts that use backslash-escaped characters + in arguments to `echo'. Bash doesn't interpret these characters. Why + not, and how can I make it understand them? +E6) Why doesn't a while or for loop get suspended when I type ^Z? +E7) What about empty for loops in Makefiles? +E8) Why does the arithmetic evaluation code complain about `08'? +E9) Why does the pattern matching expression [A-Z]* match files beginning + with every letter except `z'? +E10) Why does `cd //' leave $PWD as `//'? +E11) If I resize my xterm while another program is running, why doesn't bash + notice the change? +E12) Why don't negative offsets in substring expansion work like I expect? +E13) Why does filename completion misbehave if a colon appears in the filename? + +Section F: Things to watch out for on certain Unix versions + +F1) Why can't I use command line editing in my `cmdtool'? +F2) I built bash on Solaris 2. Why do globbing expansions and filename + completion chop off the first few characters of each filename? +F3) Why does bash dump core after I interrupt username completion or + `~user' tilde expansion on a machine running NIS? +F4) I'm running SVR4.2. Why is the line erased every time I type `@'? +F5) Why does bash report syntax errors when my C News scripts use a + redirection before a subshell command? +F6) Why can't I use vi-mode editing on Red Hat Linux 6.1? +F7) Why do bash-2.05a and bash-2.05b fail to compile `printf.def' on + HP/UX 11.x? + +Section G: How can I get bash to do certain common things? + +G1) How can I get bash to read and display eight-bit characters? +G2) How do I write a function `x' to replace builtin command `x', but + still invoke the command from within the function? +G3) How can I find the value of a shell variable whose name is the value + of another shell variable? +G4) How can I make the bash `time' reserved word print timing output that + looks like the output from my system's /usr/bin/time? +G5) How do I get the current directory into my prompt? +G6) How can I rename "*.foo" to "*.bar"? +G7) How can I translate a filename from uppercase to lowercase? +G8) How can I write a filename expansion (globbing) pattern that will match + all files in the current directory except "." and ".."? + +Section H: Where do I go from here? + +H1) How do I report bugs in bash, and where should I look for fixes and + advice? +H2) What kind of bash documentation is there? +H3) What's coming in future versions? +H4) What's on the bash `wish list'? +H5) When will the next release appear? + +---------- +Section A: The Basics + +A1) What is it? + +Bash is a Unix command interpreter (shell). It is an implementation of +the Posix 1003.2 shell standard, and resembles the Korn and System V +shells. + +Bash contains a number of enhancements over those shells, both +for interactive use and shell programming. Features geared +toward interactive use include command line editing, command +history, job control, aliases, and prompt expansion. Programming +features include additional variable expansions, shell +arithmetic, and a number of variables and options to control +shell behavior. + +Bash was originally written by Brian Fox of the Free Software +Foundation. The current developer and maintainer is Chet Ramey +of Case Western Reserve University. + +A2) What's the latest version? + +The latest version is 3.2, first made available on 12 October, 2006. + +A3) Where can I get it? + +Bash is the GNU project's shell, and so is available from the +master GNU archive site, ftp.gnu.org, and its mirrors. The +latest version is also available for FTP from ftp.cwru.edu. +The following URLs tell how to get version 3.2: + +ftp://ftp.gnu.org/pub/gnu/bash/bash-3.2.tar.gz +ftp://ftp.cwru.edu/pub/bash/bash-3.2.tar.gz + +Formatted versions of the documentation are available with the URLs: + +ftp://ftp.gnu.org/pub/gnu/bash/bash-doc-3.2.tar.gz +ftp://ftp.cwru.edu/pub/bash/bash-doc-3.2.tar.gz + +Any patches for the current version are available with the URL: + +ftp://ftp.cwru.edu/pub/bash/bash-3.2-patches/ + +A4) On what machines will bash run? + +Bash has been ported to nearly every version of Unix. All you +should have to do to build it on a machine for which a port +exists is to type `configure' and then `make'. The build process +will attempt to discover the version of Unix you have and tailor +itself accordingly, using a script created by GNU autoconf. + +More information appears in the file `INSTALL' in the distribution. + +The Bash web page (http://cnswww.cns.cwru.edu/~chet/bash/bashtop.html) +explains how to obtain binary versions of bash for most of the major +commercial Unix systems. + +A5) Will bash run on operating systems other than Unix? + +Configuration specifics for Unix-like systems such as QNX and +LynxOS are included in the distribution. Bash-2.05 and later +versions should compile and run on Minix 2.0 (patches were +contributed), but I don't believe anyone has built bash-2.x on +earlier Minix versions yet. + +Bash has been ported to versions of Windows implementing the Win32 +programming interface. This includes Windows 95 and Windows NT. +The port was done by Cygnus Solutions (now part of Red Hat) as part +of their CYGWIN project. For more information about the project, see +http://www.cygwin.com/. + +Cygnus originally ported bash-1.14.7, and that port was part of their +early GNU-Win32 (the original name) releases. Cygnus has also done +ports of bash-2.05b and bash-3.0 to the CYGWIN environment, and both +are available as part of their current release. Bash-3.2 is currently +being tested and should be available soon. + +Bash-2.05b and later versions should require no local Cygnus changes to +build and run under CYGWIN. + +DJ Delorie has a port of bash-2.x which runs under MS-DOS, as part +of the DJGPP project. For more information on the project, see + +http://www.delorie.com/djgpp/ + +I have been told that the original DJGPP port was done by Daisuke Aoyama. + +Mark Elbrecht has sent me notice that bash-2.04 +is available for DJGPP V2. The files are available as: + +ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/bsh204b.zip binary +ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/bsh204d.zip documentation +ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/bsh204s.zip source + +Mark began to work with bash-2.05, but I don't know the current status. + +Bash-3.0 compiles and runs with no modifications under Microsoft's Services +for Unix (SFU), once known as Interix. I do not anticipate any problems +with building bash-3.1 or bash-3.2. + +A6) How can I build bash with gcc? + +Bash configures to use gcc by default if it is available. Read the +file INSTALL in the distribution for more information. + +A7) How can I make bash my login shell? + +Some machines let you use `chsh' to change your login shell. Other +systems use `passwd -s' or `passwd -e'. If one of these works for +you, that's all you need. Note that many systems require the full +pathname to a shell to appear in /etc/shells before you can make it +your login shell. For this, you may need the assistance of your +friendly local system administrator. + +If you cannot do this, you can still use bash as your login shell, but +you need to perform some tricks. The basic idea is to add a command +to your login shell's startup file to replace your login shell with +bash. + +For example, if your login shell is csh or tcsh, and you have installed +bash in /usr/gnu/bin/bash, add the following line to ~/.login: + + if ( -f /usr/gnu/bin/bash ) exec /usr/gnu/bin/bash --login + +(the `--login' tells bash that it is a login shell). + +It's not a good idea to put this command into ~/.cshrc, because every +csh you run without the `-f' option, even ones started to run csh scripts, +reads that file. If you must put the command in ~/.cshrc, use something +like + + if ( $?prompt ) exec /usr/gnu/bin/bash --login + +to ensure that bash is exec'd only when the csh is interactive. + +If your login shell is sh or ksh, you have to do two things. + +First, create an empty file in your home directory named `.bash_profile'. +The existence of this file will prevent the exec'd bash from trying to +read ~/.profile, and re-execing itself over and over again. ~/.bash_profile +is the first file bash tries to read initialization commands from when +it is invoked as a login shell. + +Next, add a line similar to the above to ~/.profile: + + [ -f /usr/gnu/bin/bash ] && [ -x /usr/gnu/bin/bash ] && \ + exec /usr/gnu/bin/bash --login + +This will cause login shells to replace themselves with bash running as +a login shell. Once you have this working, you can copy your initialization +code from ~/.profile to ~/.bash_profile. + +I have received word that the recipe supplied above is insufficient for +machines running CDE. CDE has a maze of twisty little startup files, all +slightly different. + +If you cannot change your login shell in the password file to bash, you +will have to (apparently) live with CDE using the shell in the password +file to run its startup scripts. If you have changed your shell to bash, +there is code in the CDE startup files (on Solaris, at least) that attempts +to do the right thing. It is, however, often broken, and may require that +you use the $BASH_ENV trick described below. + +`dtterm' claims to use $SHELL as the default program to start, so if you +can change $SHELL in the CDE startup files, you should be able to use bash +in your terminal windows. + +Setting DTSOURCEPROFILE in ~/.dtprofile will cause the `Xsession' program +to read your login shell's startup files. You may be able to use bash for +the rest of the CDE programs by setting SHELL to bash in ~/.dtprofile as +well, but I have not tried this. + +You can use the above `exec' recipe to start bash when not logging in with +CDE by testing the value of the DT variable: + + if [ -n "$DT" ]; then + [ -f /usr/gnu/bin/bash ] && exec /usr/gnu/bin/bash --login + fi + +If CDE starts its shells non-interactively during login, the login shell +startup files (~/.profile, ~/.bash_profile) will not be sourced at login. +To get around this problem, append a line similar to the following to your +~/.dtprofile: + + BASH_ENV=${HOME}/.bash_profile ; export BASH_ENV + +and add the following line to the beginning of ~/.bash_profile: + + unset BASH_ENV + +A8) I just changed my login shell to bash, and now I can't FTP into my + machine. Why not? + +You must add the full pathname to bash to the file /etc/shells. As +noted in the answer to the previous question, many systems require +this before you can make bash your login shell. + +Most versions of ftpd use this file to prohibit `special' users +such as `uucp' and `news' from using FTP. + +A9) What's the `POSIX Shell and Utilities standard'? + +POSIX is a name originally coined by Richard Stallman for a +family of open system standards based on UNIX. There are a +number of aspects of UNIX under consideration for +standardization, from the basic system services at the system +call and C library level to applications and tools to system +administration and management. Each area of standardization is +assigned to a working group in the 1003 series. + +The POSIX Shell and Utilities standard was originally developed by +IEEE Working Group 1003.2 (POSIX.2). Today it has been merged with +the original 1003.1 Working Group and is maintained by the Austin +Group (a joint working group of the IEEE, The Open Group and +ISO/IEC SC22/WG15). Today the Shell and Utilities are a volume +within the set of documents that make up IEEE Std 1003.1-2001, and +thus now the former POSIX.2 (from 1992) is now part of the current +POSIX.1 standard (POSIX 1003.1-2001). + +The Shell and Utilities volume concentrates on the command +interpreter interface and utility programs commonly executed from +the command line or by other programs. The standard is freely +available on the web at http://www.UNIX-systems.org/version3/ . +Work continues at the Austin Group on maintenance issues; see +http://www.opengroup.org/austin/ to join the discussions. + +Bash is concerned with the aspects of the shell's behavior defined +by the POSIX Shell and Utilities volume. The shell command +language has of course been standardized, including the basic flow +control and program execution constructs, I/O redirection and +pipelining, argument handling, variable expansion, and quoting. + +The `special' builtins, which must be implemented as part of the +shell to provide the desired functionality, are specified as +being part of the shell; examples of these are `eval' and +`export'. Other utilities appear in the sections of POSIX not +devoted to the shell which are commonly (and in some cases must +be) implemented as builtin commands, such as `read' and `test'. +POSIX also specifies aspects of the shell's interactive +behavior as part of the UPE, including job control and command +line editing. Only vi-style line editing commands have been +standardized; emacs editing commands were left out due to +objections. + +The latest version of the POSIX Shell and Utilities standard is +available (now updated to the 2004 Edition) as part of the Single +UNIX Specification Version 3 at + +http://www.UNIX-systems.org/version3/ + +A10) What is the bash `posix mode'? + +Although bash is an implementation of the POSIX shell +specification, there are areas where the bash default behavior +differs from that spec. The bash `posix mode' changes the bash +behavior in these areas so that it obeys the spec more closely. + +Posix mode is entered by starting bash with the --posix or +'-o posix' option or executing `set -o posix' after bash is running. + +The specific aspects of bash which change when posix mode is +active are listed in the file POSIX in the bash distribution. +They are also listed in a section in the Bash Reference Manual +(from which that file is generated). + +Section B: The latest version + +B1) What's new in version 3.2? + +Bash-3.2 is the second maintenance release of the third major release of +bash. It contains the following significant new features (see the manual +page for complete descriptions and the CHANGES and NEWS files in the +bash-3.2 distribution). + +o Bash-3.2 now checks shell scripts for NUL characters rather than non-printing + characters when deciding whether or not a script is a binary file. + +o Quoting the string argument to the [[ command's =~ (regexp) operator now + forces string matching, as with the other pattern-matching operators. + +A short feature history dating from Bash-2.0: + +Bash-3.1 contained the following new features: + +o Bash-3.1 may now be configured and built in a mode that enforces strict + POSIX compliance. + +o The `+=' assignment operator, which appends to the value of a string or + array variable, has been implemented. + +o It is now possible to ignore case when matching in contexts other than + filename generation using the new `nocasematch' shell option. + +Bash-3.0 contained the following new features: + +o Features to support the bash debugger have been implemented, and there + is a new `extdebug' option to turn the non-default options on + +o HISTCONTROL is now a colon-separated list of options and has been + extended with a new `erasedups' option that will result in only one + copy of a command being kept in the history list + +o Brace expansion has been extended with a new {x..y} form, producing + sequences of digits or characters + +o Timestamps are now kept with history entries, with an option to save + and restore them from the history file; there is a new HISTTIMEFORMAT + variable describing how to display the timestamps when listing history + entries + +o The `[[' command can now perform extended regular expression (egrep-like) + matching, with matched subexpressions placed in the BASH_REMATCH array + variable + +o A new `pipefail' option causes a pipeline to return a failure status if + any command in it fails + +o The `jobs', `kill', and `wait' builtins now accept job control notation + in their arguments even if job control is not enabled + +o The `gettext' package and libintl have been integrated, and the shell + messages may be translated into other languages + +Bash-2.05b introduced the following new features: + +o support for multibyte characters has been added to both bash and readline + +o the DEBUG trap is now run *before* simple commands, ((...)) commands, + [[...]] conditional commands, and for ((...)) loops + +o the shell now performs arithmetic in the largest integer size the machine + supports (intmax_t) + +o there is a new \D{...} prompt expansion; passes the `...' to strftime(3) + and inserts the result into the expanded prompt + +o there is a new `here-string' redirection operator: <<< word + +o when displaying variables, function attributes and definitions are shown + separately, allowing them to be re-used as input (attempting to re-use + the old output would result in syntax errors). + +o `read' has a new `-u fd' option to read from a specified file descriptor + +o the bash debugger in examples/bashdb has been modified to work with the + new DEBUG trap semantics, the command set has been made more gdb-like, + and the changes to $LINENO make debugging functions work better + +o the expansion of $LINENO inside a shell function is only relative to the + function start if the shell is interactive -- if the shell is running a + script, $LINENO expands to the line number in the script. This is as + POSIX-2001 requires + +Bash-2.05a introduced the following new features: + +o The `printf' builtin has undergone major work + +o There is a new read-only `shopt' option: login_shell, which is set by + login shells and unset otherwise + +o New `\A' prompt string escape sequence; expanding to time in 24-hour + HH:MM format + +o New `-A group/-g' option to complete and compgen; goes group name + completion + +o New [+-]O invocation option to set and unset `shopt' options at startup + +o ksh-like `ERR' trap + +o `for' loops now allow empty word lists after the `in' reserved word + +o new `hard' and `soft' arguments for the `ulimit' builtin + +o Readline can be configured to place the user at the same point on the line + when retrieving commands from the history list + +o Readline can be configured to skip `hidden' files (filenames with a leading + `.' on Unix) when performing completion + +Bash-2.05 introduced the following new features: + +o This version has once again reverted to using locales and strcoll(3) when + processing pattern matching bracket expressions, as POSIX requires. +o Added a new `--init-file' invocation argument as a synonym for `--rcfile', + per the new GNU coding standards. +o The /dev/tcp and /dev/udp redirections now accept service names as well as + port numbers. +o `complete' and `compgen' now take a `-o value' option, which controls some + of the aspects of that compspec. Valid values are: + + default - perform bash default completion if programmable + completion produces no matches + dirnames - perform directory name completion if programmable + completion produces no matches + filenames - tell readline that the compspec produces filenames, + so it can do things like append slashes to + directory names and suppress trailing spaces +o A new loadable builtin, realpath, which canonicalizes and expands symlinks + in pathname arguments. +o When `set' is called without options, it prints function defintions in a + way that allows them to be reused as input. This affects `declare' and + `declare -p' as well. This only happens when the shell is not in POSIX + mode, since POSIX.2 forbids this behavior. + +Bash-2.04 introduced the following new features: + +o Programmable word completion with the new `complete' and `compgen' builtins; + examples are provided in examples/complete/complete-examples +o `history' has a new `-d' option to delete a history entry +o `bind' has a new `-x' option to bind key sequences to shell commands +o The prompt expansion code has new `\j' and `\l' escape sequences +o The `no_empty_cmd_completion' shell option, if enabled, inhibits + command completion when TAB is typed on an empty line +o `help' has a new `-s' option to print a usage synopsis +o New arithmetic operators: var++, var--, ++var, --var, expr1,expr2 (comma) +o New ksh93-style arithmetic for command: + for ((expr1 ; expr2; expr3 )); do list; done +o `read' has new options: `-t', `-n', `-d', `-s' +o The redirection code handles several filenames specially: /dev/fd/N, + /dev/stdin, /dev/stdout, /dev/stderr +o The redirection code now recognizes /dev/tcp/HOST/PORT and + /dev/udp/HOST/PORT and tries to open a TCP or UDP socket, respectively, + to the specified port on the specified host +o The ${!prefix*} expansion has been implemented +o A new FUNCNAME variable, which expands to the name of a currently-executing + function +o The GROUPS variable is no longer readonly +o A new shopt `xpg_echo' variable, to control the behavior of echo with + respect to backslash-escape sequences at runtime +o The NON_INTERACTIVE_LOGIN_SHELLS #define has returned + +The version of Readline released with Bash-2.04, Readline-4.1, had several +new features as well: + +o Parentheses matching is always compiled into readline, and controllable + with the new `blink-matching-paren' variable +o The history-search-forward and history-search-backward functions now leave + point at the end of the line when the search string is empty, like + reverse-search-history, and forward-search-history +o A new function for applications: rl_on_new_line_with_prompt() +o New variables for applications: rl_already_prompted, and rl_gnu_readline_p + + +Bash-2.03 had very few new features, in keeping with the convention +that odd-numbered releases provide mainly bug fixes. A number of new +features were added to Readline, mostly at the request of the Cygnus +folks. + +A new shopt option, `restricted_shell', so that startup files can test + whether or not the shell was started in restricted mode +Filename generation is now performed on the words between ( and ) in + compound array assignments (this is really a bug fix) +OLDPWD is now auto-exported, as POSIX.2 requires +ENV and BASH_ENV are read-only variables in a restricted shell +Bash may now be linked against an already-installed Readline library, + as long as the Readline library is version 4 or newer +All shells begun with the `--login' option will source the login shell + startup files, even if the shell is not interactive + +There were lots of changes to the version of the Readline library released +along with Bash-2.03. For a complete list of the changes, read the file +CHANGES in the Bash-2.03 distribution. + +Bash-2.02 contained the following new features: + +a new version of malloc (based on the old GNU malloc code in previous + bash versions) that is more page-oriented, more conservative + with memory usage, does not `orphan' large blocks when they + are freed, is usable on 64-bit machines, and has allocation + checking turned on unconditionally +POSIX.2-style globbing character classes ([:alpha:], [:alnum:], etc.) +POSIX.2-style globbing equivalence classes +POSIX.2-style globbing collating symbols +the ksh [[...]] extended conditional command +the ksh egrep-style extended pattern matching operators +a new `printf' builtin +the ksh-like $(, &>, >|, <<<, [n]<&word-, [n]>&word- + prompt string special char translation and variable expansion + auto-export of variables in initial environment + command search finds functions before builtins + bash return builtin will exit a file sourced with `.' + builtins: cd -/-L/-P, exec -l/-c/-a, echo -e/-E, hash -d/-l/-p/-t. + export -n/-f/-p/name=value, pwd -L/-P, + read -e/-p/-a/-t/-n/-d/-s/-u, + readonly -a/-f/name=value, trap -l, set +o, + set -b/-m/-o option/-h/-p/-B/-C/-H/-P, + unset -f/-v, ulimit -i/-m/-p/-q/-u/-x, + type -a/-p/-t/-f/-P, suspend -f, kill -n, + test -o optname/s1 == s2/s1 < s2/s1 > s2/-nt/-ot/-ef/-O/-G/-S + bash reads ~/.bashrc for interactive shells, $ENV for non-interactive + bash restricted shell mode is more extensive + bash allows functions and variables with the same name + brace expansion + tilde expansion + arithmetic expansion with $((...)) and `let' builtin + the `[[...]]' extended conditional command + process substitution + aliases and alias/unalias builtins + local variables in functions and `local' builtin + readline and command-line editing with programmable completion + command history and history/fc builtins + csh-like history expansion + other new bash builtins: bind, command, compgen, complete, builtin, + declare/typeset, dirs, enable, fc, help, + history, logout, popd, pushd, disown, shopt, + printf + exported functions + filename generation when using output redirection (command >a*) + POSIX.2-style globbing character classes + POSIX.2-style globbing equivalence classes + POSIX.2-style globbing collating symbols + egrep-like extended pattern matching operators + case-insensitive pattern matching and globbing + variable assignments preceding commands affect only that command, + even for builtins and functions + posix mode and strict posix conformance + redirection to /dev/fd/N, /dev/stdin, /dev/stdout, /dev/stderr, + /dev/tcp/host/port, /dev/udp/host/port + debugger support, including `caller' builtin and new variables + RETURN trap + the `+=' assignment operator + + +Things sh has that bash does not: + uses variable SHACCT to do shell accounting + includes `stop' builtin (bash can use alias stop='kill -s STOP') + `newgrp' builtin + turns on job control if called as `jsh' + $TIMEOUT (like bash $TMOUT) + `^' is a synonym for `|' + new SVR4.2 sh builtins: mldmode, priv + +Implementation differences: + redirection to/from compound commands causes sh to create a subshell + bash does not allow unbalanced quotes; sh silently inserts them at EOF + bash does not mess with signal 11 + sh sets (euid, egid) to (uid, gid) if -p not supplied and uid < 100 + bash splits only the results of expansions on IFS, using POSIX.2 + field splitting rules; sh splits all words on IFS + sh does not allow MAILCHECK to be unset (?) + sh does not allow traps on SIGALRM or SIGCHLD + bash allows multiple option arguments when invoked (e.g. -x -v); + sh allows only a single option argument (`sh -x -v' attempts + to open a file named `-v', and, on SunOS 4.1.4, dumps core. + On Solaris 2.4 and earlier versions, sh goes into an infinite + loop.) + sh exits a script if any builtin fails; bash exits only if one of + the POSIX.2 `special' builtins fails + +C2) How does bash differ from the Korn shell, version ksh88? + +Things bash has or uses that ksh88 does not: + long invocation options + [-+]O invocation option + -l invocation option + `!' reserved word + arithmetic for command: for ((expr1 ; expr2; expr3 )); do list; done + arithmetic in largest machine-supported size (intmax_t) + posix mode and posix conformance + command hashing + tilde expansion for assignment statements that look like $PATH + process substitution with named pipes if /dev/fd is not available + the ${!param} indirect parameter expansion operator + the ${!param*} prefix expansion operator + the ${param:offset[:length]} parameter substring operator + the ${param/pat[/string]} parameter pattern substitution operator + variables: BASH, BASH_VERSION, BASH_VERSINFO, UID, EUID, SHLVL, + TIMEFORMAT, HISTCMD, HOSTTYPE, OSTYPE, MACHTYPE, + HISTFILESIZE, HISTIGNORE, HISTCONTROL, PROMPT_COMMAND, + IGNOREEOF, FIGNORE, INPUTRC, HOSTFILE, DIRSTACK, + PIPESTATUS, HOSTNAME, OPTERR, SHELLOPTS, GLOBIGNORE, + GROUPS, FUNCNAME, histchars, auto_resume + prompt expansion with backslash escapes and command substitution + redirection: &> (stdout and stderr), <<<, [n]<&word-, [n]>&word- + more extensive and extensible editing and programmable completion + builtins: bind, builtin, command, declare, dirs, echo -e/-E, enable, + exec -l/-c/-a, fc -s, export -n/-f/-p, hash, help, history, + jobs -x/-r/-s, kill -s/-n/-l, local, logout, popd, pushd, + read -e/-p/-a/-t/-n/-d/-s, readonly -a/-n/-f/-p, + set -o braceexpand/-o histexpand/-o interactive-comments/ + -o notify/-o physical/-o posix/-o hashall/-o onecmd/ + -h/-B/-C/-b/-H/-P, set +o, suspend, trap -l, type, + typeset -a/-F/-p, ulimit -i/-q/-u/-x, umask -S, alias -p, + shopt, disown, printf, complete, compgen + `!' csh-style history expansion + POSIX.2-style globbing character classes + POSIX.2-style globbing equivalence classes + POSIX.2-style globbing collating symbols + egrep-like extended pattern matching operators + case-insensitive pattern matching and globbing + `**' arithmetic operator to do exponentiation + redirection to /dev/fd/N, /dev/stdin, /dev/stdout, /dev/stderr + arrays of unlimited size + TMOUT is default timeout for `read' and `select' + debugger support, including the `caller' builtin + RETURN trap + Timestamps in history entries + {x..y} brace expansion + The `+=' assignment operator + +Things ksh88 has or uses that bash does not: + tracked aliases (alias -t) + variables: ERRNO, FPATH, EDITOR, VISUAL + co-processes (|&, >&p, <&p) + weirdly-scoped functions + typeset +f to list all function names without definitions + text of command history kept in a file, not memory + builtins: alias -x, cd old new, newgrp, print, + read -p/-s/var?prompt, set -A/-o gmacs/ + -o bgnice/-o markdirs/-o trackall/-o viraw/-s, + typeset -H/-L/-R/-Z/-A/-ft/-fu/-fx/-l/-u/-t, whence + using environment to pass attributes of exported variables + arithmetic evaluation done on arguments to some builtins + reads .profile from $PWD when invoked as login shell + +Implementation differences: + ksh runs last command of a pipeline in parent shell context + bash has brace expansion by default (ksh88 compile-time option) + bash has fixed startup file for all interactive shells; ksh reads $ENV + bash has exported functions + bash command search finds functions before builtins + bash waits for all commands in pipeline to exit before returning status + emacs-mode editing has some slightly different key bindings + +C3) Which new features in ksh-93 are not in bash, and which are? + +New things in ksh-93 not in bash-3.2: + associative arrays + floating point arithmetic and variables + math library functions + ${!name[sub]} name of subscript for associative array + `.' is allowed in variable names to create a hierarchical namespace + more extensive compound assignment syntax + discipline functions + `sleep' and `getconf' builtins (bash has loadable versions) + typeset -n and `nameref' variables + KEYBD trap + variables: .sh.edchar, .sh.edmode, .sh.edcol, .sh.edtext, .sh.version, + .sh.name, .sh.subscript, .sh.value, .sh.match, HISTEDIT + backreferences in pattern matching (\N) + `&' operator in pattern lists for matching + print -f (bash uses printf) + `fc' has been renamed to `hist' + `.' can execute shell functions + exit statuses between 0 and 255 + FPATH and PATH mixing + getopts -a + -I invocation option + printf %H, %P, %T, %Z modifiers, output base for %d + lexical scoping for local variables in `ksh' functions + no scoping for local variables in `POSIX' functions + +New things in ksh-93 present in bash-3.2: + [n]<&word- and [n]>&word- redirections (combination dup and close) + for (( expr1; expr2; expr3 )) ; do list; done - arithmetic for command + ?:, ++, --, `expr1 , expr2' arithmetic operators + expansions: ${!param}, ${param:offset[:len]}, ${param/pat[/str]}, + ${!param*} + compound array assignment + the `!' reserved word + loadable builtins -- but ksh uses `builtin' while bash uses `enable' + `command', `builtin', `disown' builtins + new $'...' and $"..." quoting + FIGNORE (but bash uses GLOBIGNORE), HISTCMD + set -o notify/-C + changes to kill builtin + read -A (bash uses read -a) + read -t/-d + trap -p + exec -c/-a + `.' restores the positional parameters when it completes + POSIX.2 `test' + umask -S + unalias -a + command and arithmetic substitution performed on PS1, PS4, and ENV + command name completion + ENV processed only for interactive shells + set -o pipefail + The `+=' assignment operator + +Section D: Why does bash do some things differently than other Unix shells? + +D1) Why does bash run a different version of `command' than + `which command' says it will? + +On many systems, `which' is actually a csh script that assumes +you're running csh. In tcsh, `which' and its cousin `where' +are builtins. On other Unix systems, `which' is a perl script +that uses the PATH environment variable. + +The csh script version reads the csh startup files from your +home directory and uses those to determine which `command' will +be invoked. Since bash doesn't use any of those startup files, +there's a good chance that your bash environment differs from +your csh environment. The bash `type' builtin does everything +`which' does, and will report correct results for the running +shell. If you're really wedded to the name `which', try adding +the following function definition to your .bashrc: + + which() + { + builtin type "$@" + } + +If you're moving from tcsh and would like to bring `where' along +as well, use this function: + + where() + { + builtin type -a "$@" + } + +D2) Why doesn't bash treat brace expansions exactly like csh? + +The only difference between bash and csh brace expansion is that +bash requires a brace expression to contain at least one unquoted +comma if it is to be expanded. Any brace-surrounded word not +containing an unquoted comma is left unchanged by the brace +expansion code. This affords the greatest degree of sh +compatibility. + +Bash, ksh, zsh, and pd-ksh all implement brace expansion this way. + +D3) Why doesn't bash have csh variable modifiers? + +Posix has specified a more powerful, albeit somewhat more cryptic, +mechanism cribbed from ksh, and bash implements it. + +${parameter%word} + Remove smallest suffix pattern. The WORD is expanded to produce + a pattern. It then expands to the value of PARAMETER, with the + smallest portion of the suffix matched by the pattern deleted. + + x=file.c + echo ${x%.c}.o + -->file.o + +${parameter%%word} + + Remove largest suffix pattern. The WORD is expanded to produce + a pattern. It then expands to the value of PARAMETER, with the + largest portion of the suffix matched by the pattern deleted. + + x=posix/src/std + echo ${x%%/*} + -->posix + +${parameter#word} + Remove smallest prefix pattern. The WORD is expanded to produce + a pattern. It then expands to the value of PARAMETER, with the + smallest portion of the prefix matched by the pattern deleted. + + x=$HOME/src/cmd + echo ${x#$HOME} + -->/src/cmd + +${parameter##word} + Remove largest prefix pattern. The WORD is expanded to produce + a pattern. It then expands to the value of PARAMETER, with the + largest portion of the prefix matched by the pattern deleted. + + x=/one/two/three + echo ${x##*/} + -->three + + +Given + a=/a/b/c/d + b=b.xxx + + csh bash result + --- ---- ------ + $a:h ${a%/*} /a/b/c + $a:t ${a##*/} d + $b:r ${b%.*} b + $b:e ${b##*.} xxx + + +D4) How can I make my csh aliases work when I convert to bash? + +Bash uses a different syntax to support aliases than csh does. +The details can be found in the documentation. We have provided +a shell script which does most of the work of conversion for you; +this script can be found in ./examples/misc/aliasconv.sh. Here is +how you use it: + +Start csh in the normal way for you. (e.g., `csh') + +Pipe the output of `alias' through `aliasconv.sh', saving the +results into `bash_aliases': + + alias | bash aliasconv.sh >bash_aliases + +Edit `bash_aliases', carefully reading through any created +functions. You will need to change the names of some csh specific +variables to the bash equivalents. The script converts $cwd to +$PWD, $term to $TERM, $home to $HOME, $user to $USER, and $prompt +to $PS1. You may also have to add quotes to avoid unwanted +expansion. + +For example, the csh alias: + + alias cd 'cd \!*; echo $cwd' + +is converted to the bash function: + + cd () { command cd "$@"; echo $PWD ; } + +The only thing that needs to be done is to quote $PWD: + + cd () { command cd "$@"; echo "$PWD" ; } + +Merge the edited file into your ~/.bashrc. + +There is an additional, more ambitious, script in +examples/misc/cshtobash that attempts to convert your entire csh +environment to its bash equivalent. This script can be run as +simply `cshtobash' to convert your normal interactive +environment, or as `cshtobash ~/.login' to convert your login +environment. + +D5) How can I pipe standard output and standard error from one command to + another, like csh does with `|&'? + +Use + command 2>&1 | command2 + +The key is to remember that piping is performed before redirection, so +file descriptor 1 points to the pipe when it is duplicated onto file +descriptor 2. + +D6) Now that I've converted from ksh to bash, are there equivalents to + ksh features like autoloaded functions and the `whence' command? + +There are features in ksh-88 and ksh-93 that do not have direct bash +equivalents. Most, however, can be emulated with very little trouble. + +ksh-88 feature Bash equivalent +-------------- --------------- +compiled-in aliases set up aliases in .bashrc; some ksh aliases are + bash builtins (hash, history, type) +coprocesses named pipe pairs (one for read, one for write) +typeset +f declare -F +cd, print, whence function substitutes in examples/functions/kshenv +autoloaded functions examples/functions/autoload is the same as typeset -fu +read var?prompt read -p prompt var + +ksh-93 feature Bash equivalent +-------------- --------------- +sleep, getconf Bash has loadable versions in examples/loadables +${.sh.version} $BASH_VERSION +print -f printf +hist alias hist=fc +$HISTEDIT $FCEDIT + +Section E: How can I get bash to do certain things, and why does bash do + things the way it does? + +E1) Why is the bash builtin `test' slightly different from /bin/test? + +The specific example used here is [ ! x -o x ], which is false. + +Bash's builtin `test' implements the Posix.2 spec, which can be +summarized as follows (the wording is due to David Korn): + +Here is the set of rules for processing test arguments. + + 0 Args: False + 1 Arg: True iff argument is not null. + 2 Args: If first arg is !, True iff second argument is null. + If first argument is unary, then true if unary test is true + Otherwise error. + 3 Args: If second argument is a binary operator, do binary test of $1 $3 + If first argument is !, negate two argument test of $2 $3 + If first argument is `(' and third argument is `)', do the + one-argument test of the second argument. + Otherwise error. + 4 Args: If first argument is !, negate three argument test of $2 $3 $4. + Otherwise unspecified + 5 or more Args: unspecified. (Historical shells would use their + current algorithm). + +The operators -a and -o are considered binary operators for the purpose +of the 3 Arg case. + +As you can see, the test becomes (not (x or x)), which is false. + +E2) Why does bash sometimes say `Broken pipe'? + +If a sequence of commands appears in a pipeline, and one of the +reading commands finishes before the writer has finished, the +writer receives a SIGPIPE signal. Many other shells special-case +SIGPIPE as an exit status in the pipeline and do not report it. +For example, in: + + ps -aux | head + +`head' can finish before `ps' writes all of its output, and ps +will try to write on a pipe without a reader. In that case, bash +will print `Broken pipe' to stderr when ps is killed by a +SIGPIPE. + +As of bash-3.1, bash does not report SIGPIPE errors by default. You +can build a version of bash that will report such errors. + +E3) When I have terminal escape sequences in my prompt, why does bash + wrap lines at the wrong column? + +Readline, the line editing library that bash uses, does not know +that the terminal escape sequences do not take up space on the +screen. The redisplay code assumes, unless told otherwise, that +each character in the prompt is a `printable' character that +takes up one character position on the screen. + +You can use the bash prompt expansion facility (see the PROMPTING +section in the manual page) to tell readline that sequences of +characters in the prompt strings take up no screen space. + +Use the \[ escape to begin a sequence of non-printing characters, +and the \] escape to signal the end of such a sequence. + +E4) If I pipe the output of a command into `read variable', why doesn't + the output show up in $variable when the read command finishes? + +This has to do with the parent-child relationship between Unix +processes. It affects all commands run in pipelines, not just +simple calls to `read'. For example, piping a command's output +into a `while' loop that repeatedly calls `read' will result in +the same behavior. + +Each element of a pipeline, even a builtin or shell function, +runs in a separate process, a child of the shell running the +pipeline. A subprocess cannot affect its parent's environment. +When the `read' command sets the variable to the input, that +variable is set only in the subshell, not the parent shell. When +the subshell exits, the value of the variable is lost. + +Many pipelines that end with `read variable' can be converted +into command substitutions, which will capture the output of +a specified command. The output can then be assigned to a +variable: + + grep ^gnu /usr/lib/news/active | wc -l | read ngroup + +can be converted into + + ngroup=$(grep ^gnu /usr/lib/news/active | wc -l) + +This does not, unfortunately, work to split the text among +multiple variables, as read does when given multiple variable +arguments. If you need to do this, you can either use the +command substitution above to read the output into a variable +and chop up the variable using the bash pattern removal +expansion operators or use some variant of the following +approach. + +Say /usr/local/bin/ipaddr is the following shell script: + +#! /bin/sh +host `hostname` | awk '/address/ {print $NF}' + +Instead of using + + /usr/local/bin/ipaddr | read A B C D + +to break the local machine's IP address into separate octets, use + + OIFS="$IFS" + IFS=. + set -- $(/usr/local/bin/ipaddr) + IFS="$OIFS" + A="$1" B="$2" C="$3" D="$4" + +Beware, however, that this will change the shell's positional +parameters. If you need them, you should save them before doing +this. + +This is the general approach -- in most cases you will not need to +set $IFS to a different value. + +Some other user-supplied alternatives include: + +read A B C D << HERE + $(IFS=.; echo $(/usr/local/bin/ipaddr)) +HERE + +and, where process substitution is available, + +read A B C D < <(IFS=.; echo $(/usr/local/bin/ipaddr)) + +E5) I have a bunch of shell scripts that use backslash-escaped characters + in arguments to `echo'. Bash doesn't interpret these characters. Why + not, and how can I make it understand them? + +This is the behavior of echo on most Unix System V machines. + +The bash builtin `echo' is modeled after the 9th Edition +Research Unix version of `echo'. It does not interpret +backslash-escaped characters in its argument strings by default; +it requires the use of the -e option to enable the +interpretation. The System V echo provides no way to disable the +special characters; the bash echo has a -E option to disable +them. + +There is a configuration option that will make bash behave like +the System V echo and interpret things like `\t' by default. Run +configure with the --enable-xpg-echo-default option to turn this +on. Be aware that this will cause some of the tests run when you +type `make tests' to fail. + +There is a shell option, `xpg_echo', settable with `shopt', that will +change the behavior of echo at runtime. Enabling this option turns +on expansion of backslash-escape sequences. + +E6) Why doesn't a while or for loop get suspended when I type ^Z? + +This is a consequence of how job control works on Unix. The only +thing that can be suspended is the process group. This is a single +command or pipeline of commands that the shell forks and executes. + +When you run a while or for loop, the only thing that the shell forks +and executes are any commands in the while loop test and commands in +the loop bodies. These, therefore, are the only things that can be +suspended when you type ^Z. + +If you want to be able to stop the entire loop, you need to put it +within parentheses, which will force the loop into a subshell that +may be stopped (and subsequently restarted) as a single unit. + +E7) What about empty for loops in Makefiles? + +It's fairly common to see constructs like this in automatically-generated +Makefiles: + +SUBDIRS = @SUBDIRS@ + + ... + +subdirs-clean: + for d in ${SUBDIRS}; do \ + ( cd $$d && ${MAKE} ${MFLAGS} clean ) \ + done + +When SUBDIRS is empty, this results in a command like this being passed to +bash: + + for d in ; do + ( cd $d && ${MAKE} ${MFLAGS} clean ) + done + +In versions of bash before bash-2.05a, this was a syntax error. If the +reserved word `in' was present, a word must follow it before the semicolon +or newline. The language in the manual page referring to the list of words +being empty referred to the list after it is expanded. These versions of +bash required that there be at least one word following the `in' when the +construct was parsed. + +The idiomatic Makefile solution is something like: + +SUBDIRS = @SUBDIRS@ + +subdirs-clean: + subdirs=$SUBDIRS ; for d in $$subdirs; do \ + ( cd $$d && ${MAKE} ${MFLAGS} clean ) \ + done + +The latest updated POSIX standard has changed this: the word list +is no longer required. Bash versions 2.05a and later accept the +new syntax. + +E8) Why does the arithmetic evaluation code complain about `08'? + +The bash arithmetic evaluation code (used for `let', $(()), (()), and in +other places), interprets a leading `0' in numeric constants as denoting +an octal number, and a leading `0x' as denoting hexadecimal. This is +in accordance with the POSIX.2 spec, section 2.9.2.1, which states that +arithmetic constants should be handled as signed long integers as defined +by the ANSI/ISO C standard. + +The POSIX.2 interpretation committee has confirmed this: + +http://www.pasc.org/interps/unofficial/db/p1003.2/pasc-1003.2-173.html + +E9) Why does the pattern matching expression [A-Z]* match files beginning + with every letter except `z'? + +Bash-2.03, Bash-2.05 and later versions honor the current locale setting +when processing ranges within pattern matching bracket expressions ([A-Z]). +This is what POSIX.2 and SUSv3/XPG6 specify. + +The behavior of the matcher in bash-2.05 and later versions depends on the +current LC_COLLATE setting. Setting this variable to `C' or `POSIX' will +result in the traditional behavior ([A-Z] matches all uppercase ASCII +characters). Many other locales, including the en_US locale (the default +on many US versions of Linux) collate the upper and lower case letters like +this: + + AaBb...Zz + +which means that [A-Z] matches every letter except `z'. Others collate like + + aAbBcC...zZ + +which means that [A-Z] matches every letter except `a'. + +The portable way to specify upper case letters is [:upper:] instead of +A-Z; lower case may be specified as [:lower:] instead of a-z. + +Look at the manual pages for setlocale(3), strcoll(3), and, if it is +present, locale(1). If you have locale(1), you can use it to find +your current locale information even if you do not have any of the +LC_ variables set. + +My advice is to put + + export LC_COLLATE=C + +into /etc/profile and inspect any shell scripts run from cron for +constructs like [A-Z]. This will prevent things like + + rm [A-Z]* + +from removing every file in the current directory except those beginning +with `z' and still allow individual users to change the collation order. +Users may put the above command into their own profiles as well, of course. + +E10) Why does `cd //' leave $PWD as `//'? + +POSIX.2, in its description of `cd', says that *three* or more leading +slashes may be replaced with a single slash when canonicalizing the +current working directory. + +This is, I presume, for historical compatibility. Certain versions of +Unix, and early network file systems, used paths of the form +//hostname/path to access `path' on server `hostname'. + +E11) If I resize my xterm while another program is running, why doesn't bash + notice the change? + +This is another issue that deals with job control. + +The kernel maintains a notion of a current terminal process group. Members +of this process group (processes whose process group ID is equal to the +current terminal process group ID) receive terminal-generated signals like +SIGWINCH. (For more details, see the JOB CONTROL section of the bash +man page.) + +If a terminal is resized, the kernel sends SIGWINCH to each member of +the terminal's current process group (the `foreground' process group). + +When bash is running with job control enabled, each pipeline (which may be +a single command) is run in its own process group, different from bash's +process group. This foreground process group receives the SIGWINCH; bash +does not. Bash has no way of knowing that the terminal has been resized. + +There is a `checkwinsize' option, settable with the `shopt' builtin, that +will cause bash to check the window size and adjust its idea of the +terminal's dimensions each time a process stops or exits and returns control +of the terminal to bash. Enable it with `shopt -s checkwinsize'. + +E12) Why don't negative offsets in substring expansion work like I expect? + +When substring expansion of the form ${param:offset[:length} is used, +an `offset' that evaluates to a number less than zero counts back from +the end of the expanded value of $param. + +When a negative `offset' begins with a minus sign, however, unexpected things +can happen. Consider + + a=12345678 + echo ${a:-4} + +intending to print the last four characters of $a. The problem is that +${param:-word} already has a well-defined meaning: expand to word if the +expanded value of param is unset or null, and $param otherwise. + +To use negative offsets that begin with a minus sign, separate the +minus sign and the colon with a space. + +E13) Why does filename completion misbehave if a colon appears in the filename? + +Filename completion (and word completion in general) may appear to behave +improperly if there is a colon in the word to be completed. + +The colon is special to readline's word completion code: it is one of the +characters that breaks words for the completer. Readline uses these characters +in sort of the same way that bash uses $IFS: they break or separate the words +the completion code hands to the application-specific or default word +completion functions. The original intent was to make it easy to edit +colon-separated lists (such as $PATH in bash) in various applications using +readline for input. + +This is complicated by the fact that some versions of the popular +`bash-completion' programmable completion package have problems with the +default completion behavior in the presence of colons. + +The current set of completion word break characters is available in bash as +the value of the COMP_WORDBREAKS variable. Removing `:' from that value is +enough to make the colon not special to completion: + +COMP_WORDBREAKS=${COMP_WORDBREAKS//:} + +You can also quote the colon with a backslash to achieve the same result +temporarily. + +Section F: Things to watch out for on certain Unix versions + +F1) Why can't I use command line editing in my `cmdtool'? + +The problem is `cmdtool' and bash fighting over the input. When +scrolling is enabled in a cmdtool window, cmdtool puts the tty in +`raw mode' to permit command-line editing using the mouse for +applications that cannot do it themselves. As a result, bash and +cmdtool each try to read keyboard input immediately, with neither +getting enough of it to be useful. + +This mode also causes cmdtool to not implement many of the +terminal functions and control sequences appearing in the +`sun-cmd' termcap entry. For a more complete explanation, see +that file examples/suncmd.termcap in the bash distribution. + +`xterm' is a better choice, and gets along with bash much more +smoothly. + +If you must use cmdtool, you can use the termcap description in +examples/suncmd.termcap. Set the TERMCAP variable to the terminal +description contained in that file, i.e. + +TERMCAP='Mu|sun-cmd:am:bs:km:pt:li#34:co#80:cl=^L:ce=\E[K:cd=\E[J:rs=\E[s:' + +Then export TERMCAP and start a new cmdtool window from that shell. +The bash command-line editing should behave better in the new +cmdtool. If this works, you can put the assignment to TERMCAP +in your bashrc file. + +F2) I built bash on Solaris 2. Why do globbing expansions and filename + completion chop off the first few characters of each filename? + +This is the consequence of building bash on SunOS 5 and linking +with the libraries in /usr/ucblib, but using the definitions +and structures from files in /usr/include. + +The actual conflict is between the dirent structure in +/usr/include/dirent.h and the struct returned by the version of +`readdir' in libucb.a (a 4.3-BSD style `struct direct'). + +Make sure you've got /usr/ccs/bin ahead of /usr/ucb in your $PATH +when configuring and building bash. This will ensure that you +use /usr/ccs/bin/cc or acc instead of /usr/ucb/cc and that you +link with libc before libucb. + +If you have installed the Sun C compiler, you may also need to +put /usr/ccs/bin and /opt/SUNWspro/bin into your $PATH before +/usr/ucb. + +F3) Why does bash dump core after I interrupt username completion or + `~user' tilde expansion on a machine running NIS? + +This is a famous and long-standing bug in the SunOS YP (sorry, NIS) +client library, which is part of libc. + +The YP library code keeps static state -- a pointer into the data +returned from the server. When YP initializes itself (setpwent), +it looks at this pointer and calls free on it if it's non-null. +So far, so good. + +If one of the YP functions is interrupted during getpwent (the +exact function is interpretwithsave()), and returns NULL, the +pointer is freed without being reset to NULL, and the function +returns. The next time getpwent is called, it sees that this +pointer is non-null, calls free, and the bash free() blows up +because it's being asked to free freed memory. + +The traditional Unix mallocs allow memory to be freed multiple +times; that's probably why this has never been fixed. You can +run configure with the `--without-gnu-malloc' option to use +the C library malloc and avoid the problem. + +F4) I'm running SVR4.2. Why is the line erased every time I type `@'? + +The `@' character is the default `line kill' character in most +versions of System V, including SVR4.2. You can change this +character to whatever you want using `stty'. For example, to +change the line kill character to control-u, type + + stty kill ^U + +where the `^' and `U' can be two separate characters. + +F5) Why does bash report syntax errors when my C News scripts use a + redirection before a subshell command? + +The actual command in question is something like + + < file ( command ) + +According to the grammar given in the POSIX.2 standard, this construct +is, in fact, a syntax error. Redirections may only precede `simple +commands'. A subshell construct such as the above is one of the shell's +`compound commands'. A redirection may only follow a compound command. + +This affects the mechanical transformation of commands that use `cat' +to pipe a file into a command (a favorite Useless-Use-Of-Cat topic on +comp.unix.shell). While most commands of the form + + cat file | command + +can be converted to `< file command', shell control structures such as +loops and subshells require `command < file'. + +The file CWRU/sh-redir-hack in the bash distribution is an +(unofficial) patch to parse.y that will modify the grammar to +support this construct. It will not apply with `patch'; you must +modify parse.y by hand. Note that if you apply this, you must +recompile with -DREDIRECTION_HACK. This introduces a large +number of reduce/reduce conflicts into the shell grammar. + +F6) Why can't I use vi-mode editing on Red Hat Linux 6.1? + +The short answer is that Red Hat screwed up. + +The long answer is that they shipped an /etc/inputrc that only works +for emacs mode editing, and then screwed all the vi users by setting +INPUTRC to /etc/inputrc in /etc/profile. + +The short fix is to do one of the following: remove or rename +/etc/inputrc, set INPUTRC=~/.inputrc in ~/.bashrc (or .bash_profile, +but make sure you export it if you do), remove the assignment to +INPUTRC from /etc/profile, add + + set keymap emacs + +to the beginning of /etc/inputrc, or bracket the key bindings in +/etc/inputrc with these lines + + $if mode=emacs + [...] + $endif + +F7) Why do bash-2.05a and bash-2.05b fail to compile `printf.def' on + HP/UX 11.x? + +HP/UX's support for long double is imperfect at best. + +GCC will support it without problems, but the HP C library functions +like strtold(3) and printf(3) don't actually work with long doubles. +HP implemented a `long_double' type as a 4-element array of 32-bit +ints, and that is what the library functions use. The ANSI C +`long double' type is a 128-bit floating point scalar. + +The easiest fix, until HP fixes things up, is to edit the generated +config.h and #undef the HAVE_LONG_DOUBLE line. After doing that, +the compilation should complete successfully. + +Section G: How can I get bash to do certain common things? + +G1) How can I get bash to read and display eight-bit characters? + +This is a process requiring several steps. + +First, you must ensure that the `physical' data path is a full eight +bits. For xterms, for example, the `vt100' resources `eightBitInput' +and `eightBitOutput' should be set to `true'. + +Once you have set up an eight-bit path, you must tell the kernel and +tty driver to leave the eighth bit of characters alone when processing +keyboard input. Use `stty' to do this: + + stty cs8 -istrip -parenb + +For old BSD-style systems, you can use + + stty pass8 + +You may also need + + stty even odd + +Finally, you need to tell readline that you will be inputting and +displaying eight-bit characters. You use readline variables to do +this. These variables can be set in your .inputrc or using the bash +`bind' builtin. Here's an example using `bind': + + bash$ bind 'set convert-meta off' + bash$ bind 'set meta-flag on' + bash$ bind 'set output-meta on' + +The `set' commands between the single quotes may also be placed +in ~/.inputrc. + +The script examples/scripts.noah/meta.bash encapsulates the bind +commands in a shell function. + +G2) How do I write a function `x' to replace builtin command `x', but + still invoke the command from within the function? + +This is why the `command' and `builtin' builtins exist. The +`command' builtin executes the command supplied as its first +argument, skipping over any function defined with that name. The +`builtin' builtin executes the builtin command given as its first +argument directly. + +For example, to write a function to replace `cd' that writes the +hostname and current directory to an xterm title bar, use +something like the following: + + cd() + { + builtin cd "$@" && xtitle "$HOST: $PWD" + } + +This could also be written using `command' instead of `builtin'; +the version above is marginally more efficient. + +G3) How can I find the value of a shell variable whose name is the value + of another shell variable? + +Versions of Bash newer than Bash-2.0 support this directly. You can use + + ${!var} + +For example, the following sequence of commands will echo `z': + + var1=var2 + var2=z + echo ${!var1} + +For sh compatibility, use the `eval' builtin. The important +thing to remember is that `eval' expands the arguments you give +it again, so you need to quote the parts of the arguments that +you want `eval' to act on. + +For example, this expression prints the value of the last positional +parameter: + + eval echo \"\$\{$#\}\" + +The expansion of the quoted portions of this expression will be +deferred until `eval' runs, while the `$#' will be expanded +before `eval' is executed. In versions of bash later than bash-2.0, + + echo ${!#} + +does the same thing. + +This is not the same thing as ksh93 `nameref' variables, though the syntax +is similar. I may add namerefs in a future bash version. + +G4) How can I make the bash `time' reserved word print timing output that + looks like the output from my system's /usr/bin/time? + +The bash command timing code looks for a variable `TIMEFORMAT' and +uses its value as a format string to decide how to display the +timing statistics. + +The value of TIMEFORMAT is a string with `%' escapes expanded in a +fashion similar in spirit to printf(3). The manual page explains +the meanings of the escape sequences in the format string. + +If TIMEFORMAT is not set, bash acts as if the following assignment had +been performed: + + TIMEFORMAT=$'\nreal\t%3lR\nuser\t%3lU\nsys\t%3lS' + +The POSIX.2 default time format (used by `time -p command') is + + TIMEFORMAT=$'real %2R\nuser %2U\nsys %2S' + +The BSD /usr/bin/time format can be emulated with: + + TIMEFORMAT=$'\t%1R real\t%1U user\t%1S sys' + +The System V /usr/bin/time format can be emulated with: + + TIMEFORMAT=$'\nreal\t%1R\nuser\t%1U\nsys\t%1S' + +The ksh format can be emulated with: + + TIMEFORMAT=$'\nreal\t%2lR\nuser\t%2lU\nsys\t%2lS' + +G5) How do I get the current directory into my prompt? + +Bash provides a number of backslash-escape sequences which are expanded +when the prompt string (PS1 or PS2) is displayed. The full list is in +the manual page. + +The \w expansion gives the full pathname of the current directory, with +a tilde (`~') substituted for the current value of $HOME. The \W +expansion gives the basename of the current directory. To put the full +pathname of the current directory into the path without any tilde +subsitution, use $PWD. Here are some examples: + + PS1='\w$ ' # current directory with tilde + PS1='\W$ ' # basename of current directory + PS1='$PWD$ ' # full pathname of current directory + +The single quotes are important in the final example to prevent $PWD from +being expanded when the assignment to PS1 is performed. + +G6) How can I rename "*.foo" to "*.bar"? + +Use the pattern removal functionality described in D3. The following `for' +loop will do the trick: + + for f in *.foo; do + mv $f ${f%foo}bar + done + +G7) How can I translate a filename from uppercase to lowercase? + +The script examples/functions/lowercase, originally written by John DuBois, +will do the trick. The converse is left as an exercise. + +G8) How can I write a filename expansion (globbing) pattern that will match + all files in the current directory except "." and ".."? + +You must have set the `extglob' shell option using `shopt -s extglob' to use +this: + + echo .!(.|) * + +A solution that works without extended globbing is given in the Unix Shell +FAQ, posted periodically to comp.unix.shell. + +Section H: Where do I go from here? + +H1) How do I report bugs in bash, and where should I look for fixes and + advice? + +Use the `bashbug' script to report bugs. It is built and +installed at the same time as bash. It provides a standard +template for reporting a problem and automatically includes +information about your configuration and build environment. + +`bashbug' sends its reports to bug-bash@gnu.org, which +is a large mailing list gatewayed to the usenet newsgroup gnu.bash.bug. + +Bug fixes, answers to questions, and announcements of new releases +are all posted to gnu.bash.bug. Discussions concerning bash features +and problems also take place there. + +To reach the bash maintainers directly, send mail to +bash-maintainers@gnu.org. + +H2) What kind of bash documentation is there? + +First, look in the doc directory in the bash distribution. It should +contain at least the following files: + +bash.1 an extensive, thorough Unix-style manual page +builtins.1 a manual page covering just bash builtin commands +bashref.texi a reference manual in GNU tex`info format +bashref.info an info version of the reference manual +FAQ this file +article.ms text of an article written for The Linux Journal +readline.3 a man page describing readline + +Postscript, HTML, and ASCII files created from the above source are +available in the documentation distribution. + +There is additional documentation available for anonymous FTP from host +ftp.cwru.edu in the `pub/bash' directory. + +Cameron Newham and Bill Rosenblatt have written a book on bash, published +by O'Reilly and Associates. The book is based on Bill Rosenblatt's Korn +Shell book. The title is ``Learning the Bash Shell'', and the ISBN number +of the third edition, published in March, 2005, is 0-596-00965-8. Look for +it in fine bookstores near you. This edition of the book has been updated +to cover bash-3.0. + +The GNU Bash Reference Manual has been published as a printed book by +Network Theory Ltd (Paperback, ISBN: 0-9541617-7-7, Nov. 2006). It covers +bash-3.2 and is available from most online bookstores (see +http://www.network-theory.co.uk/bash/manual/ for details). The publisher +will donate $1 to the Free Software Foundation for each copy sold. + +Arnold Robbins and Nelson Beebe have written ``Classic Shell Scripting'', +published by O'Reilly. The first edition, with ISBN number 0-596-00595-4, +was published in May, 2005. + +Chris F. A. Johnson, a frequent contributor to comp.unix.shell and +gnu.bash.bug, has written ``Shell Scripting Recipes: A Problem-Solution +Approach,'' a new book on shell scripting, concentrating on features of +the POSIX standard helpful to shell script writers. The first edition from +Apress, with ISBN number 1-59059-471-1, was published in May, 2005. + +H3) What's coming in future versions? + +These are features I hope to include in a future version of bash. + +Rocky Bernstein's bash debugger (support is included with bash-3.0) +associative arrays +co-processes, but with a new-style syntax that looks like function declaration + +H4) What's on the bash `wish list' for future versions? + +These are features that may or may not appear in a future version of bash. + +breaking some of the shell functionality into embeddable libraries +a module system like zsh's, using dynamic loading like builtins +a bash programmer's guide with a chapter on creating loadable builtins +a better loadable interface to perl with access to the shell builtins and + variables (contributions gratefully accepted) +ksh93-like `nameref' variables +ksh93-like `xx.yy' variables (including some of the .sh.* variables) and + associated disipline functions +Some of the new ksh93 pattern matching operators, like backreferencing + +H5) When will the next release appear? + +The next version will appear sometime in 2007. Never make predictions. + +This document is Copyright 1995-2006 by Chester Ramey. + +Permission is hereby granted, without written agreement and +without license or royalty fees, to use, copy, and distribute +this document for any purpose, provided that the above copyright +notice appears in all copies of this document and that the +contents of this document remain unaltered. diff --git a/doc/Makefile.tmp b/doc/Makefile.tmp new file mode 100644 index 000000000..76763dd11 --- /dev/null +++ b/doc/Makefile.tmp @@ -0,0 +1,294 @@ +# This Makefile is for the Bash/documentation directory -*- text -*-. +# +# Copyright (C) 2003 Free Software Foundation, Inc. + +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 2, or (at your option) +# any later version. + +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. + +# You should have received a copy of the GNU General Public License +# along with this program; if not, write to the Free Software +# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111 USA. + +PACKAGE = bash +VERSION = 3.2-maint + +PACKAGE_BUGREPORT = bug-bash@gnu.org +PACKAGE_NAME = bash +PACKAGE_STRING = bash 3.2-maint +PACKAGE_VERSION = 3.2-maint + +# +SHELL = /bin/sh +RM = rm -f + +topdir = /Users/chet/src/bash/src +srcdir = /Users/chet/src/bash/src/doc +VPATH = .:/Users/chet/src/bash/src/doc + +prefix = /usr/local +exec_prefix = ${prefix} + +infodir = ${prefix}/share/info + +# set this to a directory name to have the HTML files installed +htmldir = ${docdir} + +# Support an alternate destination root directory for package building +DESTDIR = + +mandir = ${prefix}/share/man +manpfx = man + +man1ext = .1 +man1dir = $(mandir)/$(manpfx)1 +man3ext = .3 +man3dir = $(mandir)/$(manpfx)3 + +INSTALL = /usr/bin/install -c +INSTALL_DATA = ${INSTALL} -m 644 +BUILD_DIR = /usr/local/build/chet/bash/bash-current + +SUPPORT_SRCDIR = $(topdir)/support + +# bad style +RL_LIBDIR = $(topdir)/lib/readline + +# unused +TEXINDEX = texindex +TEX = tex + +MAKEINFO = makeinfo +TEXI2DVI = ${SUPPORT_SRCDIR}/texi2dvi +TEXI2HTML = ${SUPPORT_SRCDIR}/texi2html +MAN2HTML = ${BUILD_DIR}/support/man2html +HTMLPOST = ${srcdir}/htmlpost.sh +INFOPOST = ${srcdir}/infopost.sh +QUIETPS = #set this to -q to shut up dvips +PAPERSIZE = letter # change to a4 for A4-size paper +PSDPI = 600 # could be 300 if you like +DVIPS = dvips -D ${PSDPI} $(QUIETPS) -t ${PAPERSIZE} -o $@ # tricky + +TEXINPUTDIR = $(RL_LIBDIR)/doc +SET_TEXINPUTS = TEXINPUTS=.:$(TEXINPUTDIR):$$TEXINPUTS + +# These tools might not be available; they're not required +DVIPDF = dvipdfm -o $@ -p ${PAPERSIZE} +PSPDF = gs -sPAPERSIZE=${PAPERSIZE} -sDEVICE=pdfwrite -dNOPAUSE -dBATCH -sOutputFile=$@ + +MKDIRS = ${SUPPORT_SRCDIR}/mkdirs + +# This should be a program that converts troff to an ascii-readable format +NROFF = groff -Tascii + +# This should be a program that converts troff to postscript +GROFF = groff + +HSUSER = $(RL_LIBDIR)/doc/hsuser.texi +RLUSER = $(RL_LIBDIR)/doc/rluser.texi + +BASHREF_FILES = $(srcdir)/bashref.texi $(srcdir)/version.texi + +.SUFFIXES: .0 .1 .3 .ms .ps .txt .dvi .html .pdf + +.1.ps: + $(RM) $@ + -${GROFF} -man $< > $@ + +.1.0: + $(RM) $@ + -${NROFF} -man $< > $@ + +.1.html: + $(RM) $@ + -${MAN2HTML} $< | ${HTMLPOST} > $@ + +.ms.ps: + $(RM) $@ + -${GROFF} -ms $< > $@ + +.ms.txt: + $(RM) $@ + -${NROFF} -ms $< > $@ + +.3.ps: + $(RM) $@ + -${GROFF} -man $< > $@ + +.3.0: + $(RM) $@ + -${NROFF} -man $< > $@ + +.3.html: + $(RM) $@ + -${MAN2HTML} $< > $@ + +.ps.pdf: + $(RM) $@ + -${PSPDF} $< + +.dvi.pdf: + $(RM) $@ + -${DVIPDF} $< + +.dvi.ps: + ${RM} $@ + -${DVIPS} $< + +all: ps info dvi text html +nodvi: ps info text html + +PSFILES = bash.ps bashbug.ps article.ps builtins.ps rbash.ps +DVIFILES = bashref.dvi bashref.ps +INFOFILES = bashref.info +MAN0FILES = bash.0 bashbug.0 builtins.0 rbash.0 +HTMLFILES = bashref.html bash.html +PDFFILES = bash.pdf bashref.pdf article.pdf rose94.pdf + +ps: ${PSFILES} +dvi: ${DVIFILES} +info: ${INFOFILES} +text: ${MAN0FILES} +html: ${HTMLFILES} +pdf: ${PDFFILES} + +bashref.dvi: $(BASHREF_FILES) $(HSUSER) $(RLUSER) + ${SET_TEXINPUTS} $(TEXI2DVI) $(srcdir)/bashref.texi + +bashref.info: $(BASHREF_FILES) $(HSUSER) $(RLUSER) + $(MAKEINFO) --no-split -I$(TEXINPUTDIR) $(srcdir)/bashref.texi + +bashref.html: $(BASHREF_FILES) $(HSUSER) $(RLUSER) + $(TEXI2HTML) -menu -monolithic -I $(TEXINPUTDIR) $(srcdir)/bashref.texi + +b.html: $(BASHREF_FILES) $(HSUSER) $(RLUSER) + ./texi2html.debug -o $@ -verbose -menu -monolithic -I $(TEXINPUTDIR) $(srcdir)/bashref.texi + +bash.info: bashref.info + ${SHELL} ${INFOPOST} < $(srcdir)/bashref.info > $@ ; \ + +bash.txt: bash.1 +bash.ps: bash.1 +bash.html: bash.1 $(MAN2HTML) +bashbug.ps: bashbug.1 +builtins.ps: builtins.1 bash.1 +rbash.ps: rbash.1 bash.1 +bash.0: bash.1 +bashbug.0: bashbug.1 +builtins.0: builtins.1 bash.1 +rbash.0: rbash.1 bash.1 +article.ps: article.ms + +bashref.ps: bashref.dvi + +article.pdf: article.ps +bashref.pdf: bashref.dvi +bash.pdf: bash.ps +rose94.pdf: rose94.ps + +$(MAN2HTML): ${topdir}/support/man2html.c + -( cd ${BUILD_DIR}/support ; ${MAKE} ${MFLAGS} man2html) + +clean: + $(RM) *.aux *.bak *.cp *.fn *.ky *.log *.pg *.toc *.tp *.vr *.cps \ + *.pgs *.bt *.bts *.rw *.rws *.fns *.kys *.tps *.vrs *.o + ${RM} core *.core + +mostlyclean: clean + $(RM) Makefile + +distclean: clean maybe-clean + $(RM) Makefile + +maintainer-clean: clean + ${RM} ${PSFILES} ${DVIFILES} ${INFOFILES} ${MAN0FILES} ${HTMLFILES} + ${RM} ${CREATED_FAQ} + $(RM) Makefile + +maybe-clean: + -if test "X$(topdir)" != "X$(BUILD_DIR)"; then \ + $(RM) ${PSFILES} ${DVIFILES} ${INFOFILES} ${MAN0FILES} ${HTMLFILES}; \ + fi + +installdirs: + -$(SHELL) $(SUPPORT_SRCDIR)/mkinstalldirs $(DESTDIR)$(man1dir) + -$(SHELL) $(SUPPORT_SRCDIR)/mkinstalldirs $(DESTDIR)$(infodir) + -if test -n "$(htmldir)" ; then \ + $(SHELL) $(SUPPORT_SRCDIR)/mkinstalldirs $(DESTDIR)$(htmldir) ; \ + fi + +install: info installdirs bash.info + -$(INSTALL_DATA) $(srcdir)/bash.1 $(DESTDIR)$(man1dir)/bash${man1ext} + -$(INSTALL_DATA) $(srcdir)/bashbug.1 $(DESTDIR)$(man1dir)/bashbug${man1ext} +# uncomment the next line to install the builtins man page +# -$(INSTALL_DATA) $(srcdir)/builtins.1 $(DESTDIR)$(man1dir)/bash_builtins${man1ext} + -$(INSTALL_DATA) $(srcdir)/bash.info $(DESTDIR)$(infodir)/bash.info +# run install-info if it is present to update the info directory + if $(SHELL) -c 'install-info --version' >/dev/null 2>&1; then \ + install-info --dir-file=$(DESTDIR)$(infodir)/dir $(DESTDIR)$(infodir)/bash.info; \ + else true; fi +# if htmldir is set, install the html files into that directory + -if test -n "${htmldir}" ; then \ + $(INSTALL_DATA) $(srcdir)/bash.html $(DESTDIR)$(htmldir) ; \ + $(INSTALL_DATA) $(srcdir)/bashref.html $(DESTDIR)$(htmldir) ; \ + fi + +uninstall: + -$(RM) $(DESTDIR)$(man1dir)/bash${man1ext} $(DESTDIR)$(man1dir)/bashbug${man1ext} + $(RM) $(DESTDIR)$(infodir)/bash.info + -if test -n "$(htmldir)" ; then \ + $(RM) $(DESTDIR)$(htmldir)/bash.html ; \ + $(RM) $(DESTDIR)$(htmldir)/bashref.html ; \ + fi + +# for use by chet +CREATED_FAQ = faq.news faq.news2 faq.mail faq.version + +faq: ${CREATED_FAQ} + +faq.version: FAQ.version FAQ + sh mkfaqvers FAQ.version > $@ + +faq.headers.mail: FAQ.headers.mail FAQ + sh mkfaqvers FAQ.headers.mail > $@ + +faq.headers.news: FAQ.headers.news FAQ + sh mkfaqvers FAQ.headers.news > $@ + +faq.headers.news2: FAQ.headers.news2 FAQ + sh mkfaqvers FAQ.headers.news2 > $@ + +faq.news: FAQ faq.headers.news faq.version + $(RM) $@ + cat faq.headers.news faq.version FAQ > $@ + +faq.news2: FAQ faq.headers.news2 faq.version + $(RM) $@ + cat faq.headers.news2 faq.version FAQ > $@ + +faq.mail: FAQ faq.headers.mail faq.version + $(RM) $@ + cat faq.headers.mail faq.version FAQ > $@ + +inst: bashref.texi + $(SHELL) ./mkinstall + cmp -s INSTALL ../INSTALL || mv INSTALL ../INSTALL + $(RM) INSTALL + +posix: bashref.texi + $(SHELL) ./mkposix + cmp -s POSIX ../POSIX || mv POSIX ../POSIX + $(RM) POSIX + +rbash: bashref.texi + $(SH) ./mkrbash + cmp -s RBASH ../RBASH || mv RBASH ../RBASH + $(RM) RBASH + +xdist: pdf inst posix rbash diff --git a/doc/b.html b/doc/b.html new file mode 100644 index 000000000..29b0da6b9 --- /dev/null +++ b/doc/b.html @@ -0,0 +1,15448 @@ + + + + + +Bash Reference Manual: + + + + + + + + + + + + + + + + + +
[Top][Contents][Index][ ? ]
+

Bash Reference Manual

+ +This text is a brief description of the features that are present in +the Bash shell (version 3.2, 30 December 2006). +

+ +This is Edition 3.2, last updated 30 December 2006, +of The GNU Bash Reference Manual, +for Bash, Version 3.2. +

+ +Bash contains features that appear in other popular shells, and some +features that only appear in Bash. Some of the shells that Bash has +borrowed concepts from are the Bourne Shell (`sh'), the Korn Shell +(`ksh'), and the C-shell (`csh' and its successor, +`tcsh'). The following menu breaks the features up into +categories based upon which one of these other shells inspired the +feature. +

+ +This manual is meant as a brief introduction to features found in +Bash. The Bash manual page should be used as the definitive +reference on shell behavior. +

+ +

+ + + + + + + + + + + + + + +
1. Introduction  An introduction to the shell.
2. Definitions  Some definitions used in the rest of this + manual.
3. Basic Shell Features  The shell "building blocks".
4. Shell Builtin Commands  Commands that are a part of the shell.
5. Shell Variables  Variables used or set by Bash.
6. Bash Features  Features found only in Bash.
7. Job Control  What job control is and how Bash allows you + to use it.
9. Using History Interactively  Command History Expansion
8. Command Line Editing  Chapter describing the command line + editing features.
10. Installing Bash  How to build and install Bash on your system.
A. Reporting Bugs  How to report bugs in Bash.
B. Major Differences From The Bourne Shell  A terse list of the differences + between Bash and historical + versions of /bin/sh.
C. Copying This Manual  Copying this manual.
D. Indexes  Various indexes for this manual.
+

+ +

+ + + + + + + + + + + +
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+ +

1. Introduction

+ +
+ + +
1.1 What is Bash?  A short description of Bash.
1.2 What is a shell?  A brief introduction to shells.
+

+ + +

+ + + + + + + + + + + +
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+

1.1 What is Bash?

+ +

+ +Bash is the shell, or command language interpreter, +for the GNU operating system. +The name is an acronym for the `Bourne-Again SHell', +a pun on Stephen Bourne, the author of the direct ancestor of +the current Unix shell sh, +which appeared in the Seventh Edition Bell Labs Research version +of Unix. +

+ +Bash is largely compatible with sh and incorporates useful +features from the Korn shell ksh and the C shell csh. +It is intended to be a conformant implementation of the IEEE +POSIX Shell and Tools portion of the IEEE POSIX +specification (IEEE Standard 1003.1). +It offers functional improvements over sh for both interactive and +programming use. +

+ +While the GNU operating system provides other shells, including +a version of csh, Bash is the default shell. +Like other GNU software, Bash is quite portable. It currently runs +on nearly every version of Unix and a few other operating systems - +independently-supported ports exist for MS-DOS, OS/2, +and Windows platforms. +

+ + +

+ + + + + + + + + + + +
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+

1.2 What is a shell?

+ +

+ +At its base, a shell is simply a macro processor that executes +commands. The term macro processor means functionality where text +and symbols are expanded to create larger expressions. +

+ +A Unix shell is both a command interpreter and a programming +language. As a command interpreter, the shell provides the user +interface to the rich set of GNU utilities. The programming +language features allow these utilities to be combined. +Files containing commands can be created, and become +commands themselves. These new commands have the same status as +system commands in directories such as `/bin', allowing users +or groups to establish custom environments to automate their common +tasks. +

+ +Shells may be used interactively or non-interactively. In +interactive mode, they accept input typed from the keyboard. +When executing non-interactively, shells execute commands read +from a file. +

+ +A shell allows execution of GNU commands, both synchronously and +asynchronously. +The shell waits for synchronous commands to complete before accepting +more input; asynchronous commands continue to execute in parallel +with the shell while it reads and executes additional commands. +The redirection constructs permit +fine-grained control of the input and output of those commands. +Moreover, the shell allows control over the contents of commands' +environments. +

+ +Shells also provide a small set of built-in +commands (builtins) implementing functionality impossible +or inconvenient to obtain via separate utilities. +For example, cd, break, continue, and +exec) cannot be implemented outside of the shell because +they directly manipulate the shell itself. +The history, getopts, kill, or pwd +builtins, among others, could be implemented in separate utilities, +but they are more convenient to use as builtin commands. +All of the shell builtins are described in +subsequent sections. +

+ +While executing commands is essential, most of the power (and +complexity) of shells is due to their embedded programming +languages. Like any high-level language, the shell provides +variables, flow control constructs, quoting, and functions. +

+ +Shells offer features geared specifically for +interactive use rather than to augment the programming language. +These interactive features include job control, command line +editing, command history and aliases. Each of these features is +described in this manual. +

+ + +

+ + + + + + + + + + + +
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+

2. Definitions

+ +These definitions are used throughout the remainder of this manual. +

+ +

+ +
POSIX +
+A family of open system standards based on Unix. Bash +is primarily concerned with the Shell and Utilities portion of the +POSIX 1003.1 standard. +

+ +

blank +
A space or tab character. +

+ +

builtin +
+A command that is implemented internally by the shell itself, rather +than by an executable program somewhere in the file system. +

+ +

control operator +
+A word that performs a control function. It is a newline +or one of the following: +`||', `&&', `&', `;', `;;', +`|', `(', or `)'. +

+ +

exit status +
+The value returned by a command to its caller. The value is restricted +to eight bits, so the maximum value is 255. +

+ +

field +
+A unit of text that is the result of one of the shell expansions. After +expansion, when executing a command, the resulting fields are used as +the command name and arguments. +

+ +

filename +
+A string of characters used to identify a file. +

+ +

job +
+A set of processes comprising a pipeline, and any processes descended +from it, that are all in the same process group. +

+ +

job control +
+A mechanism by which users can selectively stop (suspend) and restart +(resume) execution of processes. +

+ +

metacharacter +
+A character that, when unquoted, separates words. A metacharacter is +a blank or one of the following characters: +`|', `&', `;', `(', `)', `<', or +`>'. +

+ +

name +
+ +A word consisting solely of letters, numbers, and underscores, +and beginning with a letter or underscore. Names are used as +shell variable and function names. +Also referred to as an identifier. +

+ +

operator +
+A control operator or a redirection operator. +See section 3.6 Redirections, for a list of redirection operators. +

+ +

process group +
+A collection of related processes each having the same process +group ID. +

+ +

process group ID +
+A unique identifier that represents a process group +during its lifetime. +

+ +

reserved word +
+A word that has a special meaning to the shell. Most reserved +words introduce shell flow control constructs, such as for and +while. +

+ +

return status +
+A synonym for exit status. +

+ +

signal +
+A mechanism by which a process may be notified by the kernel +of an event occurring in the system. +

+ +

special builtin +
+A shell builtin command that has been classified as special by the +POSIX standard. +

+ +

token +
+A sequence of characters considered a single unit by the shell. It is +either a word or an operator. +

+ +

word +
+A token that is not an operator. +
+

+ + +

+ + + + + + + + + + + +
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+

3. Basic Shell Features

+ +

+ +Bash is an acronym for `Bourne-Again SHell'. +The Bourne shell is +the traditional Unix shell originally written by Stephen Bourne. +All of the Bourne shell builtin commands are available in Bash, +The rules for evaluation and quoting are taken from the POSIX +specification for the `standard' Unix shell. +

+ +This chapter briefly summarizes the shell's `building blocks': +commands, control structures, shell functions, shell parameters, +shell expansions, +redirections, which are a way to direct input and output from +and to named files, and how the shell executes commands. +

+ +

+ + + + + + + + +
3.1 Shell Syntax  What your input means to the shell.
3.2 Shell Commands  The types of commands you can use.
3.3 Shell Functions  Grouping commands by name.
3.4 Shell Parameters  How the shell stores values.
3.5 Shell Expansions  How Bash expands parameters and the various + expansions available.
3.6 Redirections  A way to control where input and output go.
3.7 Executing Commands  What happens when you run a command.
3.8 Shell Scripts  Executing files of shell commands.
+

+ + +

+ + + + + + + + + + + +
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+

3.1 Shell Syntax

+ +
+ + + +
3.1.1 Shell Operation  The basic operation of the shell.
3.1.2 Quoting  How to remove the special meaning from characters.
3.1.3 Comments  How to specify comments.
+

+ +When the shell reads input, it proceeds through a +sequence of operations. If the input indicates the beginning of a +comment, the shell ignores the comment symbol (`#'), and the rest +of that line. + +Otherwise, roughly speaking, the shell reads its input and +divides the input into words and operators, employing the quoting rules +to select which meanings to assign various words and characters. +

+ +The shell then parses these tokens into commands and other constructs, +removes the special meaning of certain words or characters, expands +others, redirects input and output as needed, executes the specified +command, waits for the command's exit status, and makes that exit status +available for further inspection or processing. +

+ + +

+ + + + + + + + + + + +
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+

3.1.1 Shell Operation

+ +

+ +The following is a brief description of the shell's operation when it +reads and executes a command. Basically, the shell does the +following: +

+ +

    +
  1. +Reads its input from a file (see section 3.8 Shell Scripts), from a string +supplied as an argument to the `-c' invocation option +(see section 6.1 Invoking Bash), or from the user's terminal. +

    + +

  2. +Breaks the input into words and operators, obeying the quoting rules +described in 3.1.2 Quoting. These tokens are separated by +metacharacters. Alias expansion is performed by this step +(see section 6.6 Aliases). +

    + +

  3. +Parses the tokens into simple and compound commands +(see section 3.2 Shell Commands). +

    + +

  4. +Performs the various shell expansions (see section 3.5 Shell Expansions), breaking +the expanded tokens into lists of filenames (see section 3.5.8 Filename Expansion) +and commands and arguments. +

    + +

  5. +Performs any necessary redirections (see section 3.6 Redirections) and removes +the redirection operators and their operands from the argument list. +

    + +

  6. +Executes the command (see section 3.7 Executing Commands). +

    + +

  7. +Optionally waits for the command to complete and collects its exit +status (see section 3.7.5 Exit Status). +

    + +

+

+ + +

+ + + + + + + + + + + +
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+

3.1.2 Quoting

+ +
+ + + + + +
3.1.2.1 Escape Character  How to remove the special meaning from a single + character.
3.1.2.2 Single Quotes  How to inhibit all interpretation of a sequence + of characters.
3.1.2.3 Double Quotes  How to suppress most of the interpretation of a + sequence of characters.
3.1.2.4 ANSI-C Quoting  How to expand ANSI-C sequences in quoted strings.
3.1.2.5 Locale-Specific Translation  How to translate strings into different languages.
+

+ +Quoting is used to remove the special meaning of certain +characters or words to the shell. Quoting can be used to +disable special treatment for special characters, to prevent +reserved words from being recognized as such, and to prevent +parameter expansion. +

+ +Each of the shell metacharacters (see section 2. Definitions) +has special meaning to the shell and must be quoted if it is to +represent itself. +When the command history expansion facilities are being used +(see section 9.3 History Expansion), the +history expansion character, usually `!', must be quoted +to prevent history expansion. See section 9.1 Bash History Facilities, for +more details concerning history expansion. +

+ +There are three quoting mechanisms: the +escape character, single quotes, and double quotes. +

+ + +

+ + + + + + + + + + + +
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+

3.1.2.1 Escape Character

+ +A non-quoted backslash `\' is the Bash escape character. +It preserves the literal value of the next character that follows, +with the exception of newline. If a \newline pair +appears, and the backslash itself is not quoted, the \newline +is treated as a line continuation (that is, it is removed from +the input stream and effectively ignored). +

+ + +

+ + + + + + + + + + + +
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+

3.1.2.2 Single Quotes

+ +

+ +Enclosing characters in single quotes (`'') preserves the literal value +of each character within the quotes. A single quote may not occur +between single quotes, even when preceded by a backslash. +

+ + +

+ + + + + + + + + + + +
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+

3.1.2.3 Double Quotes

+ +

+ +Enclosing characters in double quotes (`"') preserves the literal value +of all characters within the quotes, with the exception of +`$', ``', `\', +and, when history expansion is enabled, `!'. +The characters `$' and ``' +retain their special meaning within double quotes (see section 3.5 Shell Expansions). +The backslash retains its special meaning only when followed by one of +the following characters: +`$', ``', `"', `\', or newline. +Within double quotes, backslashes that are followed by one of these +characters are removed. Backslashes preceding characters without a +special meaning are left unmodified. +A double quote may be quoted within double quotes by preceding it with +a backslash. +If enabled, history expansion will be performed unless an `!' +appearing in double quotes is escaped using a backslash. +The backslash preceding the `!' is not removed. +

+ +The special parameters `*' and `@' have special meaning +when in double quotes (see section 3.5.3 Shell Parameter Expansion). +

+ + +

+ + + + + + + + + + + +
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+

3.1.2.4 ANSI-C Quoting

+ +

+ +Words of the form $'string' are treated specially. The +word expands to string, with backslash-escaped characters replaced +as specified by the ANSI C standard. Backslash escape sequences, if +present, are decoded as follows: +

+ +

+
\a +
alert (bell) +
\b +
backspace +
\e +
an escape character (not ANSI C) +
\f +
form feed +
\n +
newline +
\r +
carriage return +
\t +
horizontal tab +
\v +
vertical tab +
\\ +
backslash +
\' +
single quote +
\nnn +
the eight-bit character whose value is the octal value nnn +(one to three digits) +
\xHH +
the eight-bit character whose value is the hexadecimal value HH +(one or two hex digits) +
\cx +
a control-x character +
+

+ +The expanded result is single-quoted, as if the dollar sign had not +been present. +

+ + +

+ + + + + + + + + + + +
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+

3.1.2.5 Locale-Specific Translation

+ +

+ +A double-quoted string preceded by a dollar sign (`$') will cause +the string to be translated according to the current locale. +If the current locale is C or POSIX, the dollar sign +is ignored. +If the string is translated and replaced, the replacement is +double-quoted. +

+ + + + +Some systems use the message catalog selected by the LC_MESSAGES +shell variable. Others create the name of the message catalog from the +value of the TEXTDOMAIN shell variable, possibly adding a +suffix of `.mo'. If you use the TEXTDOMAIN variable, you +may need to set the TEXTDOMAINDIR variable to the location of +the message catalog files. Still others use both variables in this +fashion: +TEXTDOMAINDIR/LC_MESSAGES/LC_MESSAGES/TEXTDOMAIN.mo. +

+ + +

+ + + + + + + + + + + +
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+

3.1.3 Comments

+ +

+ +In a non-interactive shell, or an interactive shell in which the +interactive_comments option to the shopt +builtin is enabled (see section 4.3.2 The Shopt Builtin), +a word beginning with `#' +causes that word and all remaining characters on that line to +be ignored. An interactive shell without the interactive_comments +option enabled does not allow comments. The interactive_comments +option is on by default in interactive shells. +See section 6.3 Interactive Shells, for a description of what makes +a shell interactive. +

+ + +

+ + + + + + + + + + + +
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+

3.2 Shell Commands

+ +

+ +A simple shell command such as echo a b c consists of the command +itself followed by arguments, separated by spaces. +

+ +More complex shell commands are composed of simple commands arranged together +in a variety of ways: in a pipeline in which the output of one command +becomes the input of a second, in a loop or conditional construct, or in +some other grouping. +

+ +

+ + + + +
3.2.1 Simple Commands  The most common type of command.
3.2.2 Pipelines  Connecting the input and output of several + commands.
3.2.3 Lists of Commands  How to execute commands sequentially.
3.2.4 Compound Commands  Shell commands for control flow.
+

+ + +

+ + + + + + + + + + + +
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+

3.2.1 Simple Commands

+ +

+ +A simple command is the kind of command encountered most often. +It's just a sequence of words separated by blanks, terminated +by one of the shell's control operators (see section 2. Definitions). The +first word generally specifies a command to be executed, with the +rest of the words being that command's arguments. +

+ +The return status (see section 3.7.5 Exit Status) of a simple command is +its exit status as provided +by the POSIX 1003.1 waitpid function, or 128+n if +the command was terminated by signal n. +

+ + +

+ + + + + + + + + + + +
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+

3.2.2 Pipelines

+ +

+ +A pipeline is a sequence of simple commands separated by +`|'. +

+ + + + +The format for a pipeline is +
 
[time [-p]] [!] command1 [| command2 ...]
+

+ +The output of each command in the pipeline is connected via a pipe +to the input of the next command. +That is, each command reads the previous command's output. +

+ +The reserved word time causes timing statistics +to be printed for the pipeline once it finishes. +The statistics currently consist of elapsed (wall-clock) time and +user and system time consumed by the command's execution. +The `-p' option changes the output format to that specified +by POSIX. +The TIMEFORMAT variable may be set to a format string that +specifies how the timing information should be displayed. +See section 5.2 Bash Variables, for a description of the available formats. +The use of time as a reserved word permits the timing of +shell builtins, shell functions, and pipelines. An external +time command cannot time these easily. +

+ +If the pipeline is not executed asynchronously (see section 3.2.3 Lists of Commands), the +shell waits for all commands in the pipeline to complete. +

+ +Each command in a pipeline is executed in its own subshell +(see section 3.7.3 Command Execution Environment). The exit +status of a pipeline is the exit status of the last command in the +pipeline, unless the pipefail option is enabled +(see section 4.3.1 The Set Builtin). +If pipefail is enabled, the pipeline's return status is the +value of the last (rightmost) command to exit with a non-zero status, +or zero if all commands exit successfully. +If the reserved word `!' precedes the pipeline, the +exit status is the logical negation of the exit status as described +above. +The shell waits for all commands in the pipeline to terminate before +returning a value. +

+ + +

+ + + + + + + + + + + +
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+

3.2.3 Lists of Commands

+ +

+ +A list is a sequence of one or more pipelines separated by one +of the operators `;', `&', `&&', or `||', +and optionally terminated by one of `;', `&', or a +newline. +

+ +Of these list operators, `&&' and `||' +have equal precedence, followed by `;' and `&', +which have equal precedence. +

+ +A sequence of one or more newlines may appear in a list +to delimit commands, equivalent to a semicolon. +

+ +If a command is terminated by the control operator `&', +the shell executes the command asynchronously in a subshell. +This is known as executing the command in the background. +The shell does not wait for the command to finish, and the return +status is 0 (true). +When job control is not active (see section 7. Job Control), +the standard input for asynchronous commands, in the absence of any +explicit redirections, is redirected from /dev/null. +

+ +Commands separated by a `;' are executed sequentially; the shell +waits for each command to terminate in turn. The return status is the +exit status of the last command executed. +

+ +The control operators `&&' and `||' +denote AND lists and OR lists, respectively. +An AND list has the form +
 
command1 && command2
+

+ +command2 is executed if, and only if, command1 +returns an exit status of zero. +

+ +An OR list has the form +
 
command1 || command2
+

+ +command2 is executed if, and only if, command1 +returns a non-zero exit status. +

+ +The return status of +AND and OR lists is the exit status of the last command +executed in the list. +

+ + +

+ + + + + + + + + + + +
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+

3.2.4 Compound Commands

+ +

+ +

+ + + +
3.2.4.1 Looping Constructs  Shell commands for iterative action.
3.2.4.2 Conditional Constructs  Shell commands for conditional execution.
3.2.4.3 Grouping Commands  Ways to group commands.
+

+ +Compound commands are the shell programming constructs. +Each construct begins with a reserved word or control operator and is +terminated by a corresponding reserved word or operator. +Any redirections (see section 3.6 Redirections) associated with a compound command +apply to all commands within that compound command unless explicitly overridden. +

+ +Bash provides looping constructs, conditional commands, and mechanisms +to group commands and execute them as a unit. +

+ + +

+ + + + + + + + + + + +
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+

3.2.4.1 Looping Constructs

+ +

+ +Bash supports the following looping constructs. +

+ +Note that wherever a `;' appears in the description of a +command's syntax, it may be replaced with one or more newlines. +

+ +

+
until +
+ + +The syntax of the until command is: +
 
until test-commands; do consequent-commands; done
+
Execute consequent-commands as long as +test-commands has an exit status which is not zero. +The return status is the exit status of the last command executed +in consequent-commands, or zero if none was executed. +

+ +

while +
+The syntax of the while command is: +
 
while test-commands; do consequent-commands; done
+

+ +Execute consequent-commands as long as +test-commands has an exit status of zero. +The return status is the exit status of the last command executed +in consequent-commands, or zero if none was executed. +

+ +

for +
+The syntax of the for command is: +

+ +
 
for name [in words ...]; do commands; done
+
Expand words, and execute commands once for each member +in the resultant list, with name bound to the current member. +If `in words' is not present, the for command +executes the commands once for each positional parameter that is +set, as if `in "$@"' had been specified +(see section 3.4.2 Special Parameters). +The return status is the exit status of the last command that executes. +If there are no items in the expansion of words, no commands are +executed, and the return status is zero. +

+ +An alternate form of the for command is also supported: +

+ +
 
for (( expr1 ; expr2 ; expr3 )) ; do commands ; done
+
First, the arithmetic expression expr1 is evaluated according +to the rules described below (see section 6.5 Shell Arithmetic). +The arithmetic expression expr2 is then evaluated repeatedly +until it evaluates to zero. +Each time expr2 evaluates to a non-zero value, commands are +executed and the arithmetic expression expr3 is evaluated. +If any expression is omitted, it behaves as if it evaluates to 1. +The return value is the exit status of the last command in list +that is executed, or false if any of the expressions is invalid. +

+ +

+

+ +The break and continue builtins (see section 4.1 Bourne Shell Builtins) +may be used to control loop execution. +

+ + +

+ + + + + + + + + + + +
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+

3.2.4.2 Conditional Constructs

+ +

+ +

+
if +
+ + + + +The syntax of the if command is: +

+ +
 
if test-commands; then
+  consequent-commands;
+[elif more-test-commands; then
+  more-consequents;]
+[else alternate-consequents;]
+fi
+

+ +The test-commands list is executed, and if its return status is zero, +the consequent-commands list is executed. +If test-commands returns a non-zero status, each elif list +is executed in turn, and if its exit status is zero, +the corresponding more-consequents is executed and the +command completes. +If `else alternate-consequents' is present, and +the final command in the final if or elif clause +has a non-zero exit status, then alternate-consequents is executed. +The return status is the exit status of the last command executed, or +zero if no condition tested true. +

+ +

case +
+ + +The syntax of the case command is: +

+ +
 
case word in [ [(] pattern [| pattern]...) command-list ;;]... esac
+

+ +case will selectively execute the command-list corresponding to +the first pattern that matches word. +If the shell option nocasematch +(see the description of shopt in 4.3.2 The Shopt Builtin) +is enabled, the match is performed without regard to the case +of alphabetic characters. +The `|' is used to separate multiple patterns, and the `)' +operator terminates a pattern list. +A list of patterns and an associated command-list is known +as a clause. Each clause must be terminated with `;;'. +The word undergoes tilde expansion, parameter expansion, command +substitution, arithmetic expansion, and quote removal before matching is +attempted. Each pattern undergoes tilde expansion, parameter +expansion, command substitution, and arithmetic expansion. +

+ +There may be an arbitrary number of case clauses, each terminated +by a `;;'. The first pattern that matches determines the +command-list that is executed. +

+ +Here is an example using case in a script that could be used to +describe one interesting feature of an animal: +

+ +
 
echo -n "Enter the name of an animal: "
+read ANIMAL
+echo -n "The $ANIMAL has "
+case $ANIMAL in
+  horse | dog | cat) echo -n "four";;
+  man | kangaroo ) echo -n "two";;
+  *) echo -n "an unknown number of";;
+esac
+echo " legs."
+

+ +The return status is zero if no pattern is matched. Otherwise, the +return status is the exit status of the command-list executed. +

+ +

select +
+

+ +The select construct allows the easy generation of menus. +It has almost the same syntax as the for command: +

+ +
 
select name [in words ...]; do commands; done
+

+ +The list of words following in is expanded, generating a list +of items. The set of expanded words is printed on the standard +error output stream, each preceded by a number. If the +`in words' is omitted, the positional parameters are printed, +as if `in "$@"' had been specified. +The PS3 prompt is then displayed and a line is read from the +standard input. +If the line consists of a number corresponding to one of the displayed +words, then the value of name is set to that word. +If the line is empty, the words and prompt are displayed again. +If EOF is read, the select command completes. +Any other value read causes name to be set to null. +The line read is saved in the variable REPLY. +

+ +The commands are executed after each selection until a +break command is executed, at which +point the select command completes. +

+ +Here is an example that allows the user to pick a filename from the +current directory, and displays the name and index of the file +selected. +

+ +
 
select fname in *;
+do
+	echo you picked $fname \($REPLY\)
+	break;
+done
+

+ +

((...)) +
 
(( expression ))
+

+ +The arithmetic expression is evaluated according to the rules +described below (see section 6.5 Shell Arithmetic). +If the value of the expression is non-zero, the return status is 0; +otherwise the return status is 1. This is exactly equivalent to +
 
let "expression"
+
See section 4.2 Bash Builtin Commands, for a full description of the let builtin. +

+ +

[[...]] +
+ +
 
[[ expression ]]
+

+ +Return a status of 0 or 1 depending on the evaluation of +the conditional expression expression. +Expressions are composed of the primaries described below in +6.4 Bash Conditional Expressions. +Word splitting and filename expansion are not performed on the words +between the `[[' and `]]'; tilde expansion, parameter and +variable expansion, arithmetic expansion, command substitution, process +substitution, and quote removal are performed. +Conditional operators such as `-f' must be unquoted to be recognized +as primaries. +

+ +When the `==' and `!=' operators are used, the string to the +right of the operator is considered a pattern and matched according +to the rules described below in 3.5.8.1 Pattern Matching. +If the shell option nocasematch +(see the description of shopt in 4.3.2 The Shopt Builtin) +is enabled, the match is performed without regard to the case +of alphabetic characters. +The return value is 0 if the string matches (`==') or does not +match (`!=')the pattern, and 1 otherwise. +Any part of the pattern may be quoted to force it to be matched as a +string. +

+ +An additional binary operator, `=~', is available, with the same +precedence as `==' and `!='. +When it is used, the string to the right of the operator is considered +an extended regular expression and matched accordingly (as in regex3)). +The return value is 0 if the string matches +the pattern, and 1 otherwise. +If the regular expression is syntactically incorrect, the conditional +expression's return value is 2. +If the shell option nocasematch +(see the description of shopt in 4.3.2 The Shopt Builtin) +is enabled, the match is performed without regard to the case +of alphabetic characters. +Substrings matched by parenthesized subexpressions within the regular +expression are saved in the array variable BASH_REMATCH. +The element of BASH_REMATCH with index 0 is the portion of the string +matching the entire regular expression. +The element of BASH_REMATCH with index n is the portion of the +string matching the nth parenthesized subexpression. +

+ +Expressions may be combined using the following operators, listed +in decreasing order of precedence: +

+ +

+
( expression ) +
Returns the value of expression. +This may be used to override the normal precedence of operators. +

+ +

! expression +
True if expression is false. +

+ +

expression1 && expression2 +
True if both expression1 and expression2 are true. +

+ +

expression1 || expression2 +
True if either expression1 or expression2 is true. +
+The && and || operators do not evaluate expression2 if the +value of expression1 is sufficient to determine the return +value of the entire conditional expression. +

+ +

+

+ + +

+ + + + + + + + + + + +
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+

3.2.4.3 Grouping Commands

+ +

+ +Bash provides two ways to group a list of commands to be executed +as a unit. When commands are grouped, redirections may be applied +to the entire command list. For example, the output of all the +commands in the list may be redirected to a single stream. +

+ +

+
() +
 
( list )
+

+ +Placing a list of commands between parentheses causes a subshell +environment to be created (see section 3.7.3 Command Execution Environment), and each +of the commands in list to be executed in that subshell. Since the +list is executed in a subshell, variable assignments do not remain in +effect after the subshell completes. +

+ +

{} +
+ +
 
{ list; }
+

+ +Placing a list of commands between curly braces causes the list to +be executed in the current shell context. No subshell is created. +The semicolon (or newline) following list is required. +

+

+ +In addition to the creation of a subshell, there is a subtle difference +between these two constructs due to historical reasons. The braces +are reserved words, so they must be separated from the list +by blanks. The parentheses are operators, and are +recognized as separate tokens by the shell even if they are not separated +from the list by whitespace. +

+ +The exit status of both of these constructs is the exit status of +list. +

+ + +

+ + + + + + + + + + + +
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+

3.3 Shell Functions

+ +

+ +Shell functions are a way to group commands for later execution +using a single name for the group. They are executed just like +a "regular" command. +When the name of a shell function is used as a simple command name, +the list of commands associated with that function name is executed. +Shell functions are executed in the current +shell context; no new process is created to interpret them. +

+ +Functions are declared using this syntax: + +
 
[ function ] name () compound-command [ redirections ]
+

+ +This defines a shell function named name. The reserved +word function is optional. +If the function reserved +word is supplied, the parentheses are optional. +The body of the function is the compound command +compound-command (see section 3.2.4 Compound Commands). +That command is usually a list enclosed between { and }, but +may be any compound command listed above. +compound-command is executed whenever name is specified as the +name of a command. +Any redirections (see section 3.6 Redirections) associated with the shell function +are performed when the function is executed. +

+ +A function definition may be deleted using the `-f' option to the +unset builtin (see section 4.1 Bourne Shell Builtins). +

+ +The exit status of a function definition is zero unless a syntax error +occurs or a readonly function with the same name already exists. +When executed, the exit status of a function is the exit status of the +last command executed in the body. +

+ +Note that for historical reasons, in the most common usage the curly braces +that surround the body of the function must be separated from the body by +blanks or newlines. +This is because the braces are reserved words and are only recognized +as such when they are separated by whitespace. +Also, when using the braces, the list must be terminated by a semicolon, +a `&', or a newline. +

+ +When a function is executed, the arguments to the +function become the positional parameters +during its execution (see section 3.4.1 Positional Parameters). +The special parameter `#' that expands to the number of +positional parameters is updated to reflect the change. +Special parameter 0 is unchanged. +The first element of the FUNCNAME variable is set to the +name of the function while the function is executing. +All other aspects of the shell execution +environment are identical between a function and its caller +with the exception that the DEBUG and RETURN traps +are not inherited unless the function has been given the +trace attribute using the declare builtin or +the -o functrace option has been enabled with +the set builtin, +(in which case all functions inherit the DEBUG and RETURN traps). +See section 4.1 Bourne Shell Builtins, for the description of the +trap builtin. +

+ +If the builtin command return +is executed in a function, the function completes and +execution resumes with the next command after the function +call. +Any command associated with the RETURN trap is executed +before execution resumes. +When a function completes, the values of the +positional parameters and the special parameter `#' +are restored to the values they had prior to the function's +execution. If a numeric argument is given to return, +that is the function's return status; otherwise the function's +return status is the exit status of the last command executed +before the return. +

+ +Variables local to the function may be declared with the +local builtin. These variables are visible only to +the function and the commands it invokes. +

+ +Function names and definitions may be listed with the +`-f' option to the declare or typeset +builtin commands (see section 4.2 Bash Builtin Commands). +The `-F' option to declare or typeset +will list the function names only +(and optionally the source file and line number, if the extdebug +shell option is enabled). +Functions may be exported so that subshells +automatically have them defined with the +`-f' option to the export builtin +(see section 4.1 Bourne Shell Builtins). +Note that shell functions and variables with the same name may result +in multiple identically-named entries in the environment passed to the +shell's children. +Care should be taken in cases where this may cause a problem. +

+ +Functions may be recursive. No limit is placed on the number of +recursive calls. +

+ + +

+ + + + + + + + + + + +
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+

3.4 Shell Parameters

+ +

+ +

+ + +
3.4.1 Positional Parameters  The shell's command-line arguments.
3.4.2 Special Parameters  Parameters denoted by special characters.
+

+ +A parameter is an entity that stores values. +It can be a name, a number, or one of the special characters +listed below. +A variable is a parameter denoted by a name. +A variable has a value and zero or more attributes. +Attributes are assigned using the declare builtin command +(see the description of the declare builtin in 4.2 Bash Builtin Commands). +

+ +A parameter is set if it has been assigned a value. The null string is +a valid value. Once a variable is set, it may be unset only by using +the unset builtin command. +

+ +A variable may be assigned to by a statement of the form +
 
name=[value]
+
If value +is not given, the variable is assigned the null string. All +values undergo tilde expansion, parameter and variable expansion, +command substitution, arithmetic expansion, and quote +removal (detailed below). If the variable has its integer +attribute set, then value +is evaluated as an arithmetic expression even if the $((...)) +expansion is not used (see section 3.5.5 Arithmetic Expansion). +Word splitting is not performed, with the exception +of "$@" as explained below. +Filename expansion is not performed. +Assignment statements may also appear as arguments to the +alias, +declare, typeset, export, readonly, +and local builtin commands. +

+ +In the context where an assignment statement is assigning a value +to a shell variable or array index (see section 6.7 Arrays), the `+=' +operator can be used to +append to or add to the variable's previous value. +When `+=' is applied to a variable for which the integer attribute +has been set, value is evaluated as an arithmetic expression and +added to the variable's current value, which is also evaluated. +When `+=' is applied to an array variable using compound assignment +(see section 6.7 Arrays), the +variable's value is not unset (as it is when using `='), and new +values are appended to the array beginning at one greater than the array's +maximum index. +When applied to a string-valued variable, value is expanded and +appended to the variable's value. +

+ + +

+ + + + + + + + + + + +
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+

3.4.1 Positional Parameters

+ +

+ +A positional parameter is a parameter denoted by one or more +digits, other than the single digit 0. Positional parameters are +assigned from the shell's arguments when it is invoked, +and may be reassigned using the set builtin command. +Positional parameter N may be referenced as ${N}, or +as $N when N consists of a single digit. +Positional parameters may not be assigned to with assignment statements. +The set and shift builtins are used to set and +unset them (see section 4. Shell Builtin Commands). +The positional parameters are +temporarily replaced when a shell function is executed +(see section 3.3 Shell Functions). +

+ +When a positional parameter consisting of more than a single +digit is expanded, it must be enclosed in braces. +

+ + +

+ + + + + + + + + + + +
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+

3.4.2 Special Parameters

+ +

+ +The shell treats several parameters specially. These parameters may +only be referenced; assignment to them is not allowed. +

+ +

+ + +
* +
+Expands to the positional parameters, starting from one. When the +expansion occurs within double quotes, it expands to a single word +with the value of each parameter separated by the first character +of the IFS +special variable. That is, "$*" is equivalent +to "$1c$2c...", where c +is the first character of the value of the IFS +variable. +If IFS is unset, the parameters are separated by spaces. +If IFS is null, the parameters are joined without intervening +separators. +

+ + +

@ +
+Expands to the positional parameters, starting from one. When the +expansion occurs within double quotes, each parameter expands to a +separate word. That is, "$@" is equivalent to +"$1" "$2" .... +If the double-quoted expansion occurs within a word, the expansion of +the first parameter is joined with the beginning part of the original +word, and the expansion of the last parameter is joined with the last +part of the original word. +When there are no positional parameters, "$@" and +$@ +expand to nothing (i.e., they are removed). +

+ + +

# +
+Expands to the number of positional parameters in decimal. +

+ + +

? +
+Expands to the exit status of the most recently executed foreground +pipeline. +

+ + +

- +
+(A hyphen.) Expands to the current option flags as specified upon +invocation, by the set +builtin command, or those set by the shell itself +(such as the `-i' option). +

+ + +

$ +
+Expands to the process ID of the shell. In a () subshell, it +expands to the process ID of the invoking shell, not the subshell. +

+ + +

! +
+Expands to the process ID of the most recently executed background +(asynchronous) command. +

+ + +

0 +
+Expands to the name of the shell or shell script. This is set at +shell initialization. If Bash is invoked with a file of commands +(see section 3.8 Shell Scripts), $0 is set to the name of that file. +If Bash is started with the `-c' option (see section 6.1 Invoking Bash), +then $0 is set to the first argument after the string to be +executed, if one is present. Otherwise, it is set +to the filename used to invoke Bash, as given by argument zero. +

+ + +

_ +
+(An underscore.) +At shell startup, set to the absolute pathname used to invoke the +shell or shell script being executed as passed in the environment +or argument list. +Subsequently, expands to the last argument to the previous command, +after expansion. +Also set to the full pathname used to invoke each command executed +and placed in the environment exported to that command. +When checking mail, this parameter holds the name of the mail file. +
+

+ + +

+ + + + + + + + + + + +
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+

3.5 Shell Expansions

+ +

+ +Expansion is performed on the command line after it has been split into +tokens. There are seven kinds of expansion performed: +

    +
  • brace expansion +
  • tilde expansion +
  • parameter and variable expansion +
  • command substitution +
  • arithmetic expansion +
  • word splitting +
  • filename expansion +
+

+ +

+ + + + + + + + + +
3.5.1 Brace Expansion  Expansion of expressions within braces.
3.5.2 Tilde Expansion  Expansion of the ~ character.
3.5.3 Shell Parameter Expansion  How Bash expands variables to their values.
3.5.4 Command Substitution  Using the output of a command as an argument.
3.5.5 Arithmetic Expansion  How to use arithmetic in shell expansions.
3.5.6 Process Substitution  A way to write and read to and from a + command.
3.5.7 Word Splitting  How the results of expansion are split into separate + arguments.
3.5.8 Filename Expansion  A shorthand for specifying filenames matching patterns.
3.5.9 Quote Removal  How and when quote characters are removed from + words.
+

+ +The order of expansions is: brace expansion, tilde expansion, +parameter, variable, and arithmetic expansion and +command substitution +(done in a left-to-right fashion), word splitting, and filename +expansion. +

+ +On systems that can support it, there is an additional expansion +available: process substitution. This is performed at the +same time as parameter, variable, and arithmetic expansion and +command substitution. +

+ +Only brace expansion, word splitting, and filename expansion +can change the number of words of the expansion; other expansions +expand a single word to a single word. +The only exceptions to this are the expansions of +"$@" (see section 3.4.2 Special Parameters) and "${name[@]}" +(see section 6.7 Arrays). +

+ +After all expansions, quote removal (see section 3.5.9 Quote Removal) +is performed. +

+ + +

+ + + + + + + + + + + +
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+

3.5.1 Brace Expansion

+ +

+ +Brace expansion is a mechanism by which arbitrary strings may be generated. +This mechanism is similar to +filename expansion (see section 3.5.8 Filename Expansion), +but the file names generated need not exist. +Patterns to be brace expanded take the form of an optional preamble, +followed by either a series of comma-separated strings or a seqeunce expression +between a pair of braces, +followed by an optional postscript. +The preamble is prefixed to each string contained within the braces, and +the postscript is then appended to each resulting string, expanding left +to right. +

+ +Brace expansions may be nested. +The results of each expanded string are not sorted; left to right order +is preserved. +For example, +
 
bash$ echo a{d,c,b}e
+ade ace abe
+

+ +A sequence expression takes the form {x..y}, +where x and y are either integers or single characters. +When integers are supplied, the expression expands to each number between +x and y, inclusive. +When characters are supplied, the expression expands to each character +lexicographically between x and y, inclusive. Note that +both x and y must be of the same type. +

+ +Brace expansion is performed before any other expansions, +and any characters special to other expansions are preserved +in the result. It is strictly textual. Bash +does not apply any syntactic interpretation to the context of the +expansion or the text between the braces. +To avoid conflicts with parameter expansion, the string `${' +is not considered eligible for brace expansion. +

+ +A correctly-formed brace expansion must contain unquoted opening +and closing braces, and at least one unquoted comma or a valid +sequence expression. +Any incorrectly formed brace expansion is left unchanged. +

+ +A { or `,' may be quoted with a backslash to prevent its +being considered part of a brace expression. +To avoid conflicts with parameter expansion, the string `${' +is not considered eligible for brace expansion. +

+ +This construct is typically used as shorthand when the common +prefix of the strings to be generated is longer than in the +above example: +
 
mkdir /usr/local/src/bash/{old,new,dist,bugs}
+
or +
 
chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}}
+

+ + +

+ + + + + + + + + + + +
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+

3.5.2 Tilde Expansion

+ +

+ +If a word begins with an unquoted tilde character (`~'), all of the +characters up to the first unquoted slash (or all characters, +if there is no unquoted slash) are considered a tilde-prefix. +If none of the characters in the tilde-prefix are quoted, the +characters in the tilde-prefix following the tilde are treated as a +possible login name. +If this login name is the null string, the tilde is replaced with the +value of the HOME shell variable. +If HOME is unset, the home directory of the user executing the +shell is substituted instead. +Otherwise, the tilde-prefix is replaced with the home directory +associated with the specified login name. +

+ +If the tilde-prefix is `~+', the value of +the shell variable PWD replaces the tilde-prefix. +If the tilde-prefix is `~-', the value of the shell variable +OLDPWD, if it is set, is substituted. +

+ +If the characters following the tilde in the tilde-prefix consist of a +number N, optionally prefixed by a `+' or a `-', +the tilde-prefix is replaced with the +corresponding element from the directory stack, as it would be displayed +by the dirs builtin invoked with the characters following tilde +in the tilde-prefix as an argument (see section 6.8 The Directory Stack). +If the tilde-prefix, sans the tilde, consists of a number without a +leading `+' or `-', `+' is assumed. +

+ +If the login name is invalid, or the tilde expansion fails, the word is +left unchanged. +

+ +Each variable assignment is checked for unquoted tilde-prefixes immediately +following a `:' or the first `='. +In these cases, tilde expansion is also performed. +Consequently, one may use file names with tildes in assignments to +PATH, MAILPATH, and CDPATH, +and the shell assigns the expanded value. +

+ +The following table shows how Bash treats unquoted tilde-prefixes: +

+ +

+
~ +
The value of $HOME +
~/foo +
`$HOME/foo' +

+ +

~fred/foo +
The subdirectory foo of the home directory of the user +fred +

+ +

~+/foo +
`$PWD/foo' +

+ +

~-/foo +
`${OLDPWD-'~-'}/foo' +

+ +

~N +
The string that would be displayed by `dirs +N' +

+ +

~+N +
The string that would be displayed by `dirs +N' +

+ +

~-N +
The string that would be displayed by `dirs -N' +

+ +

+

+ + +

+ + + + + + + + + + + +
[ < ][ > ]   [ << ][ Up ][ >> ]         [Top][Contents][Index][ ? ]
+

3.5.3 Shell Parameter Expansion

+ +

+ +The `$' character introduces parameter expansion, +command substitution, or arithmetic expansion. The parameter name +or symbol to be expanded may be enclosed in braces, which +are optional but serve to protect the variable to be expanded from +characters immediately following it which could be +interpreted as part of the name. +

+ +When braces are used, the matching ending brace is the first `}' +not escaped by a backslash or within a quoted string, and not within an +embedded arithmetic expansion, command substitution, or parameter +expansion. +

+ +The basic form of parameter expansion is ${parameter}. +The value of parameter is substituted. The braces are required +when parameter +is a positional parameter with more than one digit, +or when parameter +is followed by a character that is not to be +interpreted as part of its name. +

+ +If the first character of parameter is an exclamation point, +a level of variable indirection is introduced. +Bash uses the value of the variable formed from the rest of +parameter as the name of the variable; this variable is then +expanded and that value is used in the rest of the substitution, rather +than the value of parameter itself. +This is known as indirect expansion. +The exceptions to this are the expansions of ${!prefix*} +and ${!name[@]} +described below. +The exclamation point must immediately follow the left brace in order to +introduce indirection. +

+ +In each of the cases below, word is subject to tilde expansion, +parameter expansion, command substitution, and arithmetic expansion. +

+ +When not performing substring expansion, Bash tests for a parameter +that is unset or null; omitting the colon results in a test only for a +parameter that is unset. Put another way, if the colon is included, +the operator tests for both existence and that the value is not null; +if the colon is omitted, the operator tests only for existence. +

+ +

+ +
${parameter:-word} +
If parameter is unset or null, the expansion of +word is substituted. Otherwise, the value of +parameter is substituted. +

+ +

${parameter:=word} +
If parameter +is unset or null, the expansion of word +is assigned to parameter. +The value of parameter is then substituted. +Positional parameters and special parameters may not be assigned to +in this way. +

+ +

${parameter:?word} +
If parameter +is null or unset, the expansion of word (or a message +to that effect if word +is not present) is written to the standard error and the shell, if it +is not interactive, exits. Otherwise, the value of parameter is +substituted. +

+ +

${parameter:+word} +
If parameter +is null or unset, nothing is substituted, otherwise the expansion of +word is substituted. +

+ +

${parameter:offset} +
${parameter:offset:length} +
Expands to up to length characters of parameter +starting at the character specified by offset. +If length is omitted, expands to the substring of +parameter starting at the character specified by offset. +length and offset are arithmetic expressions +(see section 6.5 Shell Arithmetic). +This is referred to as Substring Expansion. +

+ +length must evaluate to a number greater than or equal to zero. +If offset evaluates to a number less than zero, the value +is used as an offset from the end of the value of parameter. +If parameter is `@', the result is length positional +parameters beginning at offset. +If parameter is an array name indexed by `@' or `*', +the result is the length +members of the array beginning with ${parameter[offset]}. +A negative offset is taken relative to one greater than the maximum +index of the specified array. +Note that a negative offset must be separated from the colon by at least +one space to avoid being confused with the `:-' expansion. +Substring indexing is zero-based unless the positional parameters +are used, in which case the indexing starts at 1 by default. +If offset is 0, and the positional parameters are used, $@ is +prefixed to the list. +

+ +

${!prefix*} +
${!prefix@} +
Expands to the names of variables whose names begin with prefix, +separated by the first character of the IFS special variable. +When `@' is used and the expansion appears within double quotes, each +variable name expands to a separate word. +

+ +

${!name[@]} +
${!name[*]} +
If name is an array variable, expands to the list of array indices +(keys) assigned in name. +If name is not an array, expands to 0 if name is set and null +otherwise. +When `@' is used and the expansion appears within double quotes, each +key expands to a separate word. +

+ +

${#parameter} +
The length in characters of the expanded value of parameter is +substituted. +If parameter is `*' or `@', the value substituted +is the number of positional parameters. +If parameter is an array name subscripted by `*' or `@', +the value substituted is the number of elements in the array. +

+ +

${parameter#word} +
${parameter##word} +
The word +is expanded to produce a pattern just as in filename +expansion (see section 3.5.8 Filename Expansion). If the pattern matches +the beginning of the expanded value of parameter, +then the result of the expansion is the expanded value of parameter +with the shortest matching pattern (the `#' case) or the +longest matching pattern (the `##' case) deleted. +If parameter is `@' or `*', +the pattern removal operation is applied to each positional +parameter in turn, and the expansion is the resultant list. +If parameter is an array variable subscripted with +`@' or `*', +the pattern removal operation is applied to each member of the +array in turn, and the expansion is the resultant list. +

+ +

${parameter%word} +
${parameter%%word} +
The word is expanded to produce a pattern just as in +filename expansion. +If the pattern matches a trailing portion of the expanded value of +parameter, then the result of the expansion is the value of +parameter with the shortest matching pattern (the `%' case) +or the longest matching pattern (the `%%' case) deleted. +If parameter is `@' or `*', +the pattern removal operation is applied to each positional +parameter in turn, and the expansion is the resultant list. +If parameter +is an array variable subscripted with `@' or `*', +the pattern removal operation is applied to each member of the +array in turn, and the expansion is the resultant list. +

+ +

${parameter/pattern/string} +

+ +The pattern is expanded to produce a pattern just as in +filename expansion. +Parameter is expanded and the longest match of pattern +against its value is replaced with string. +If pattern begins with `/', all matches of pattern are +replaced with string. Normally only the first match is replaced. +If pattern begins with `#', it must match at the beginning +of the expanded value of parameter. +If pattern begins with `%', it must match at the end +of the expanded value of parameter. +If string is null, matches of pattern are deleted +and the / following pattern may be omitted. +If parameter is `@' or `*', +the substitution operation is applied to each positional +parameter in turn, and the expansion is the resultant list. +If parameter +is an array variable subscripted with `@' or `*', +the substitution operation is applied to each member of the +array in turn, and the expansion is the resultant list. +

+ +

+

+ + +

+ + + + + + + + + + + +
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+

3.5.4 Command Substitution

+ +

+ +Command substitution allows the output of a command to replace +the command itself. +Command substitution occurs when a command is enclosed as follows: +
 
$(command)
+
or +
 
`command`
+

+ +Bash performs the expansion by executing command and +replacing the command substitution with the standard output of the +command, with any trailing newlines deleted. +Embedded newlines are not deleted, but they may be removed during +word splitting. +The command substitution $(cat file) can be +replaced by the equivalent but faster $(< file). +

+ +When the old-style backquote form of substitution is used, +backslash retains its literal meaning except when followed by +`$', ``', or `\'. +The first backquote not preceded by a backslash terminates the +command substitution. +When using the $(command) form, all characters between +the parentheses make up the command; none are treated specially. +

+ +Command substitutions may be nested. To nest when using the backquoted +form, escape the inner backquotes with backslashes. +

+ +If the substitution appears within double quotes, word splitting and +filename expansion are not performed on the results. +

+ + +

+ + + + + + + + + + + +
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+

3.5.5 Arithmetic Expansion

+ +

+ +Arithmetic expansion allows the evaluation of an arithmetic expression +and the substitution of the result. The format for arithmetic expansion is: +

+ +
 
$(( expression ))
+

+ +The expression is treated as if it were within double quotes, but +a double quote inside the parentheses is not treated specially. +All tokens in the expression undergo parameter expansion, command +substitution, and quote removal. +Arithmetic expansions may be nested. +

+ +The evaluation is performed according to the rules listed below +(see section 6.5 Shell Arithmetic). +If the expression is invalid, Bash prints a message indicating +failure to the standard error and no substitution occurs. +

+ + +

+ + + + + + + + + + + +
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+

3.5.6 Process Substitution

+ +

+ +Process substitution is supported on systems that support named +pipes (FIFOs) or the `/dev/fd' method of naming open files. +It takes the form of +
 
<(list)
+
or +
 
>(list)
+
The process list is run with its input or output connected to a +FIFO or some file in `/dev/fd'. The name of this file is +passed as an argument to the current command as the result of the +expansion. If the >(list) form is used, writing to +the file will provide input for list. If the +<(list) form is used, the file passed as an +argument should be read to obtain the output of list. +Note that no space may appear between the < or > +and the left parenthesis, otherwise the construct would be interpreted +as a redirection. +

+ +When available, process substitution is performed simultaneously with +parameter and variable expansion, command substitution, and arithmetic +expansion. +

+ + +

+ + + + + + + + + + + +
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+

3.5.7 Word Splitting

+ +

+ +The shell scans the results of parameter expansion, command substitution, +and arithmetic expansion that did not occur within double quotes for +word splitting. +

+ +The shell treats each character of $IFS as a delimiter, and splits +the results of the other expansions into words on these characters. +If IFS is unset, or its value is exactly <space><tab><newline>, +the default, then sequences of + <space>, <tab>, and <newline> +at the beginning and end of the results of the previous +expansions are ignored, and any sequence of IFS +characters not at the beginning or end serves to delimit words. +If IFS has a value other than the default, then sequences of +the whitespace characters space and tab +are ignored at the beginning and end of the +word, as long as the whitespace character is in the +value of IFS (an IFS whitespace character). +Any character in IFS that is not IFS +whitespace, along with any adjacent IFS +whitespace characters, delimits a field. A sequence of IFS +whitespace characters is also treated as a delimiter. +If the value of IFS is null, no word splitting occurs. +

+ +Explicit null arguments ("" or ") are retained. +Unquoted implicit null arguments, resulting from the expansion of +parameters that have no values, are removed. +If a parameter with no value is expanded within double quotes, a +null argument results and is retained. +

+ +Note that if no expansion occurs, no splitting +is performed. +

+ + +

+ + + + + + + + + + + +
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+

3.5.8 Filename Expansion

+ +
+ +
3.5.8.1 Pattern Matching  How the shell matches patterns.
+ + + + +

+ +After word splitting, unless the `-f' option has been set +(see section 4.3.1 The Set Builtin), Bash scans each word for the characters +`*', `?', and `['. +If one of these characters appears, then the word is +regarded as a pattern, +and replaced with an alphabetically sorted list of +file names matching the pattern. If no matching file names are found, +and the shell option nullglob is disabled, the word is left +unchanged. +If the nullglob option is set, and no matches are found, the word +is removed. +If the failglob shell option is set, and no matches are found, +an error message is printed and the command is not executed. +If the shell option nocaseglob is enabled, the match is performed +without regard to the case of alphabetic characters. +

+ +When a pattern is used for filename generation, the character `.' +at the start of a filename or immediately following a slash +must be matched explicitly, unless the shell option dotglob is set. +When matching a file name, the slash character must always be +matched explicitly. +In other cases, the `.' character is not treated specially. +

+ +See the description of shopt in 4.3.2 The Shopt Builtin, +for a description of the nocaseglob, nullglob, +failglob, and dotglob options. +

+ +The GLOBIGNORE +shell variable may be used to restrict the set of filenames matching a +pattern. If GLOBIGNORE +is set, each matching filename that also matches one of the patterns in +GLOBIGNORE is removed from the list of matches. The filenames +`.' and `..' +are always ignored when GLOBIGNORE +is set and not null. +However, setting GLOBIGNORE to a non-null value has the effect of +enabling the dotglob +shell option, so all other filenames beginning with a +`.' will match. +To get the old behavior of ignoring filenames beginning with a +`.', make `.*' one of the patterns in GLOBIGNORE. +The dotglob option is disabled when GLOBIGNORE +is unset. +

+ + +

+ + + + + + + + + + + +
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+

3.5.8.1 Pattern Matching

+ +

+ +Any character that appears in a pattern, other than the special pattern +characters described below, matches itself. +The NUL character may not occur in a pattern. +A backslash escapes the following character; the +escaping backslash is discarded when matching. +The special pattern characters must be quoted if they are to be matched +literally. +

+ +The special pattern characters have the following meanings: +

+
* +
Matches any string, including the null string. +
? +
Matches any single character. +
[...] +
Matches any one of the enclosed characters. A pair of characters +separated by a hyphen denotes a range expression; +any character that sorts between those two characters, inclusive, +using the current locale's collating sequence and character set, +is matched. If the first character following the +`[' is a `!' or a `^' +then any character not enclosed is matched. A `-' +may be matched by including it as the first or last character +in the set. A `]' may be matched by including it as the first +character in the set. +The sorting order of characters in range expressions is determined by +the current locale and the value of the LC_COLLATE shell variable, +if set. +

+ +For example, in the default C locale, `[a-dx-z]' is equivalent to +`[abcdxyz]'. Many locales sort characters in dictionary order, and in +these locales `[a-dx-z]' is typically not equivalent to `[abcdxyz]'; +it might be equivalent to `[aBbCcDdxXyYz]', for example. To obtain +the traditional interpretation of ranges in bracket expressions, you can +force the use of the C locale by setting the LC_COLLATE or +LC_ALL environment variable to the value `C'. +

+ +Within `[' and `]', character classes can be specified +using the syntax +[:class:], where class is one of the +following classes defined in the POSIX standard: +
 
alnum   alpha   ascii   blank   cntrl   digit   graph   lower
+print   punct   space   upper   word    xdigit
+
A character class matches any character belonging to that class. +The word character class matches letters, digits, and the character +`_'. +

+ +Within `[' and `]', an equivalence class can be +specified using the syntax [=c=], which +matches all characters with the same collation weight (as defined +by the current locale) as the character c. +

+ +Within `[' and `]', the syntax [.symbol.] +matches the collating symbol symbol. +

+

+ +If the extglob shell option is enabled using the shopt +builtin, several extended pattern matching operators are recognized. +In the following description, a pattern-list is a list of one +or more patterns separated by a `|'. +Composite patterns may be formed using one or more of the following +sub-patterns: +

+ +

+
?(pattern-list) +
Matches zero or one occurrence of the given patterns. +

+ +

*(pattern-list) +
Matches zero or more occurrences of the given patterns. +

+ +

+(pattern-list) +
Matches one or more occurrences of the given patterns. +

+ +

@(pattern-list) +
Matches one of the given patterns. +

+ +

!(pattern-list) +
Matches anything except one of the given patterns. +
+

+ + +

+ + + + + + + + + + + +
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+

3.5.9 Quote Removal

+ +

+ +After the preceding expansions, all unquoted occurrences of the +characters `\', `'', and `"' that did not +result from one of the above expansions are removed. +

+ + +

+ + + + + + + + + + + +
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+

3.6 Redirections

+ +

+ +Before a command is executed, its input and output +may be redirected +using a special notation interpreted by the shell. +Redirection may also be used to open and close files for the +current shell execution environment. The following redirection +operators may precede or appear anywhere within a +simple command or may follow a command. +Redirections are processed in the order they appear, from +left to right. +

+ +In the following descriptions, if the file descriptor number is +omitted, and the first character of the redirection operator is +`<', the redirection refers to the standard input (file +descriptor 0). If the first character of the redirection operator +is `>', the redirection refers to the standard output (file +descriptor 1). +

+ +The word following the redirection operator in the following +descriptions, unless otherwise noted, is subjected to brace expansion, +tilde expansion, parameter expansion, command substitution, arithmetic +expansion, quote removal, filename expansion, and word splitting. +If it expands to more than one word, Bash reports an error. +

+ +Note that the order of redirections is significant. For example, +the command +
 
ls > dirlist 2>&1
+
directs both standard output (file descriptor 1) and standard error +(file descriptor 2) to the file dirlist, while the command +
 
ls 2>&1 > dirlist
+
directs only the standard output to file dirlist, +because the standard error was duplicated as standard output +before the standard output was redirected to dirlist. +

+ +Bash handles several filenames specially when they are used in +redirections, as described in the following table: +

+ +

+
/dev/fd/fd +
If fd is a valid integer, file descriptor fd is duplicated. +

+ +

/dev/stdin +
File descriptor 0 is duplicated. +

+ +

/dev/stdout +
File descriptor 1 is duplicated. +

+ +

/dev/stderr +
File descriptor 2 is duplicated. +

+ +

/dev/tcp/host/port +
If host is a valid hostname or Internet address, and port +is an integer port number or service name, Bash attempts to open a TCP +connection to the corresponding socket. +

+ +

/dev/udp/host/port +
If host is a valid hostname or Internet address, and port +is an integer port number or service name, Bash attempts to open a UDP +connection to the corresponding socket. +

+ +

+

+ +A failure to open or create a file causes the redirection to fail. +

+ +Redirections using file descriptors greater than 9 should be used with +care, as they may conflict with file descriptors the shell uses +internally. +

+ +

+ + + + + + + + + + + +
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+

3.6.1 Redirecting Input

+ +Redirection of input causes the file whose name results from +the expansion of word +to be opened for reading on file descriptor n, +or the standard input (file descriptor 0) if n +is not specified. +

+ +The general format for redirecting input is: +
 
[n]<word
+

+ +

+ + + + + + + + + + + +
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+

3.6.2 Redirecting Output

+ +Redirection of output causes the file whose name results from +the expansion of word +to be opened for writing on file descriptor n, +or the standard output (file descriptor 1) if n +is not specified. If the file does not exist it is created; +if it does exist it is truncated to zero size. +

+ +The general format for redirecting output is: +
 
[n]>[|]word
+

+ +If the redirection operator is `>', and the noclobber +option to the set builtin has been enabled, the redirection +will fail if the file whose name results from the expansion of +word exists and is a regular file. +If the redirection operator is `>|', or the redirection operator is +`>' and the noclobber option is not enabled, the redirection +is attempted even if the file named by word exists. +

+ +

+ + + + + + + + + + + +
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+

3.6.3 Appending Redirected Output

+ +Redirection of output in this fashion +causes the file whose name results from +the expansion of word +to be opened for appending on file descriptor n, +or the standard output (file descriptor 1) if n +is not specified. If the file does not exist it is created. +

+ +The general format for appending output is: +
 
[n]>>word
+

+ +

+ + + + + + + + + + + +
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+

3.6.4 Redirecting Standard Output and Standard Error

+ +Bash allows both the +standard output (file descriptor 1) and +the standard error output (file descriptor 2) +to be redirected to the file whose name is the +expansion of word with this construct. +

+ +There are two formats for redirecting standard output and +standard error: +
 
&>word
+
and +
 
>&word
+
Of the two forms, the first is preferred. +This is semantically equivalent to +
 
>word 2>&1
+

+ +

+ + + + + + + + + + + +
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+

3.6.5 Here Documents

+ +This type of redirection instructs the shell to read input from the +current source until a line containing only word +(with no trailing blanks) is seen. All of +the lines read up to that point are then used as the standard +input for a command. +

+ +The format of here-documents is: +
 
<<[-]word
+        here-document
+delimiter
+

+ +No parameter expansion, command substitution, arithmetic expansion, +or filename expansion is performed on +word. If any characters in word are quoted, the +delimiter is the result of quote removal on word, +and the lines in the here-document are not expanded. +If word is unquoted, +all lines of the here-document are subjected to parameter expansion, +command substitution, and arithmetic expansion. In the latter +case, the character sequence \newline is ignored, and `\' +must be used to quote the characters +`\', `$', and ``'. +

+ +If the redirection operator is `<<-', +then all leading tab characters are stripped from input lines and the +line containing delimiter. +This allows here-documents within shell scripts to be indented in a +natural fashion. +

+ +

+ + + + + + + + + + + +
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+

3.6.6 Here Strings

+ +A variant of here documents, the format is: +
 
<<< word
+

+ +The word is expanded and supplied to the command on its standard +input. +

+ +

+ + + + + + + + + + + +
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+

3.6.7 Duplicating File Descriptors

+ +The redirection operator +
 
[n]<&word
+
is used to duplicate input file descriptors. +If word +expands to one or more digits, the file descriptor denoted by n +is made to be a copy of that file descriptor. +If the digits in word do not specify a file descriptor open for +input, a redirection error occurs. +If word +evaluates to `-', file descriptor n is closed. If +n is not specified, the standard input (file descriptor 0) is used. +

+ +The operator +
 
[n]>&word
+
is used similarly to duplicate output file descriptors. If +n is not specified, the standard output (file descriptor 1) is used. +If the digits in word do not specify a file descriptor open for +output, a redirection error occurs. +As a special case, if n is omitted, and word does not +expand to one or more digits, the standard output and standard +error are redirected as described previously. +

+ +

+ + + + + + + + + + + +
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+

3.6.8 Moving File Descriptors

+ +The redirection operator +
 
[n]<&digit-
+
moves the file descriptor digit to file descriptor n, +or the standard input (file descriptor 0) if n is not specified. +digit is closed after being duplicated to n. +

+ +Similarly, the redirection operator +
 
[n]>&digit-
+
moves the file descriptor digit to file descriptor n, +or the standard output (file descriptor 1) if n is not specified. +

+ +

+ + + + + + + + + + + +
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+

3.6.9 Opening File Descriptors for Reading and Writing

+ +The redirection operator +
 
[n]<>word
+
causes the file whose name is the expansion of word +to be opened for both reading and writing on file descriptor +n, or on file descriptor 0 if n +is not specified. If the file does not exist, it is created. +

+ + +

+ + + + + + + + + + + +
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+

3.7 Executing Commands

+ +

+ +

+ + + + + + +
3.7.1 Simple Command Expansion  How Bash expands simple commands before + executing them.
3.7.2 Command Search and Execution  How Bash finds commands and runs them.
3.7.3 Command Execution Environment  The environment in which Bash + executes commands that are not + shell builtins.
3.7.4 Environment  The environment given to a command.
3.7.5 Exit Status  The status returned by commands and how Bash + interprets it.
3.7.6 Signals  What happens when Bash or a command it runs + receives a signal.
+

+ + +

+ + + + + + + + + + + +
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+

3.7.1 Simple Command Expansion

+ +

+ +When a simple command is executed, the shell performs the following +expansions, assignments, and redirections, from left to right. +

+ +

    +
  1. +The words that the parser has marked as variable assignments (those +preceding the command name) and redirections are saved for later +processing. +

    + +

  2. +The words that are not variable assignments or redirections are +expanded (see section 3.5 Shell Expansions). +If any words remain after expansion, the first word +is taken to be the name of the command and the remaining words are +the arguments. +

    + +

  3. +Redirections are performed as described above (see section 3.6 Redirections). +

    + +

  4. +The text after the `=' in each variable assignment undergoes tilde +expansion, parameter expansion, command substitution, arithmetic expansion, +and quote removal before being assigned to the variable. +
+

+ +If no command name results, the variable assignments affect the current +shell environment. Otherwise, the variables are added to the environment +of the executed command and do not affect the current shell environment. +If any of the assignments attempts to assign a value to a readonly variable, +an error occurs, and the command exits with a non-zero status. +

+ +If no command name results, redirections are performed, but do not +affect the current shell environment. A redirection error causes the +command to exit with a non-zero status. +

+ +If there is a command name left after expansion, execution proceeds as +described below. Otherwise, the command exits. If one of the expansions +contained a command substitution, the exit status of the command is +the exit status of the last command substitution performed. If there +were no command substitutions, the command exits with a status of zero. +

+ + +

+ + + + + + + + + + + +
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+

3.7.2 Command Search and Execution

+ +

+ +After a command has been split into words, if it results in a +simple command and an optional list of arguments, the following +actions are taken. +

+ +

    +
  1. +If the command name contains no slashes, the shell attempts to +locate it. If there exists a shell function by that name, that +function is invoked as described in 3.3 Shell Functions. +

    + +

  2. +If the name does not match a function, the shell searches for +it in the list of shell builtins. If a match is found, that +builtin is invoked. +

    + +

  3. +If the name is neither a shell function nor a builtin, +and contains no slashes, Bash searches each element of +$PATH for a directory containing an executable file +by that name. Bash uses a hash table to remember the full +pathnames of executable files to avoid multiple PATH searches +(see the description of hash in 4.1 Bourne Shell Builtins). +A full search of the directories in $PATH +is performed only if the command is not found in the hash table. +If the search is unsuccessful, the shell prints an error +message and returns an exit status of 127. +

    + +

  4. +If the search is successful, or if the command name contains +one or more slashes, the shell executes the named program in +a separate execution environment. +Argument 0 is set to the name given, and the remaining arguments +to the command are set to the arguments supplied, if any. +

    + +

  5. +If this execution fails because the file is not in executable +format, and the file is not a directory, it is assumed to be a +shell script and the shell executes it as described in +3.8 Shell Scripts. +

    + +

  6. +If the command was not begun asynchronously, the shell waits for +the command to complete and collects its exit status. +

    + +

+

+ + +

+ + + + + + + + + + + +
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+

3.7.3 Command Execution Environment

+ +

+ +The shell has an execution environment, which consists of the +following: +

+ +

    +
  • +open files inherited by the shell at invocation, as modified by +redirections supplied to the exec builtin +

    + +

  • +the current working directory as set by cd, pushd, or +popd, or inherited by the shell at invocation +

    + +

  • +the file creation mode mask as set by umask or inherited from +the shell's parent +

    + +

  • +current traps set by trap +

    + +

  • +shell parameters that are set by variable assignment or with set +or inherited from the shell's parent in the environment +

    + +

  • +shell functions defined during execution or inherited from the shell's +parent in the environment +

    + +

  • +options enabled at invocation (either by default or with command-line +arguments) or by set +

    + +

  • +options enabled by shopt (see section 4.3.2 The Shopt Builtin) +

    + +

  • +shell aliases defined with alias (see section 6.6 Aliases) +

    + +

  • +various process IDs, including those of background jobs +(see section 3.2.3 Lists of Commands), the value of $$, and the value of +$PPID +

    + +

+

+ +When a simple command other than a builtin or shell function +is to be executed, it +is invoked in a separate execution environment that consists of +the following. Unless otherwise noted, the values are inherited +from the shell. +

+ +

    +
  • +the shell's open files, plus any modifications and additions specified +by redirections to the command +

    + +

  • +the current working directory +

    + +

  • +the file creation mode mask +

    + +

  • +shell variables and functions marked for export, along with variables +exported for the command, passed in the environment (see section 3.7.4 Environment) +

    + +

  • +traps caught by the shell are reset to the values inherited from the +shell's parent, and traps ignored by the shell are ignored +

    + +

+

+ +A command invoked in this separate environment cannot affect the +shell's execution environment. +

+ +Command substitution, commands grouped with parentheses, +and asynchronous commands are invoked in a +subshell environment that is a duplicate of the shell environment, +except that traps caught by the shell are reset to the values +that the shell inherited from its parent at invocation. Builtin +commands that are invoked as part of a pipeline are also executed +in a subshell environment. Changes made to the subshell environment +cannot affect the shell's execution environment. +

+ +If a command is followed by a `&' and job control is not active, the +default standard input for the command is the empty file `/dev/null'. +Otherwise, the invoked command inherits the file descriptors of the calling +shell as modified by redirections. +

+ + +

+ + + + + + + + + + + +
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+

3.7.4 Environment

+ +

+ +When a program is invoked it is given an array of strings +called the environment. +This is a list of name-value pairs, of the form name=value. +

+ +Bash provides several ways to manipulate the environment. +On invocation, the shell scans its own environment and +creates a parameter for each name found, automatically marking +it for export +to child processes. Executed commands inherit the environment. +The export and `declare -x' +commands allow parameters and functions to be added to and +deleted from the environment. If the value of a parameter +in the environment is modified, the new value becomes part +of the environment, replacing the old. The environment +inherited by any executed command consists of the shell's +initial environment, whose values may be modified in the shell, +less any pairs removed by the unset and `export -n' +commands, plus any additions via the export and +`declare -x' commands. +

+ +The environment for any simple command +or function may be augmented temporarily by prefixing it with +parameter assignments, as described in 3.4 Shell Parameters. +These assignment statements affect only the environment seen +by that command. +

+ +If the `-k' option is set (see section 4.3.1 The Set Builtin), then all +parameter assignments are placed in the environment for a command, +not just those that precede the command name. +

+ +When Bash invokes an external command, the variable `$_' +is set to the full path name of the command and passed to that +command in its environment. +

+ + +

+ + + + + + + + + + + +
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+

3.7.5 Exit Status

+ +

+ +For the shell's purposes, a command which exits with a +zero exit status has succeeded. +A non-zero exit status indicates failure. +This seemingly counter-intuitive scheme is used so there +is one well-defined way to indicate success and a variety of +ways to indicate various failure modes. +When a command terminates on a fatal signal whose number is N, +Bash uses the value 128+N as the exit status. +

+ +If a command is not found, the child process created to +execute it returns a status of 127. If a command is found +but is not executable, the return status is 126. +

+ +If a command fails because of an error during expansion or redirection, +the exit status is greater than zero. +

+ +The exit status is used by the Bash conditional commands +(see section 3.2.4.2 Conditional Constructs) and some of the list +constructs (see section 3.2.3 Lists of Commands). +

+ +All of the Bash builtins return an exit status of zero if they succeed +and a non-zero status on failure, so they may be used by the +conditional and list constructs. +All builtins return an exit status of 2 to indicate incorrect usage. +

+ + +

+ + + + + + + + + + + +
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+

3.7.6 Signals

+ +

+ +When Bash is interactive, in the absence of any traps, it ignores +SIGTERM (so that `kill 0' does not kill an interactive shell), +and SIGINT +is caught and handled (so that the wait builtin is interruptible). +When Bash receives a SIGINT, it breaks out of any executing loops. +In all cases, Bash ignores SIGQUIT. +If job control is in effect (see section 7. Job Control), Bash +ignores SIGTTIN, SIGTTOU, and SIGTSTP. +

+ +Non-builtin commands started by Bash have signal handlers set to the +values inherited by the shell from its parent. +When job control is not in effect, asynchronous commands +ignore SIGINT and SIGQUIT in addition to these inherited +handlers. +Commands run as a result of +command substitution ignore the keyboard-generated job control signals +SIGTTIN, SIGTTOU, and SIGTSTP. +

+ +The shell exits by default upon receipt of a SIGHUP. +Before exiting, an interactive shell resends the SIGHUP to +all jobs, running or stopped. +Stopped jobs are sent SIGCONT to ensure that they receive +the SIGHUP. +To prevent the shell from sending the SIGHUP signal to a +particular job, it should be removed +from the jobs table with the disown +builtin (see section 7.2 Job Control Builtins) or marked +to not receive SIGHUP using disown -h. +

+ +If the huponexit shell option has been set with shopt +(see section 4.3.2 The Shopt Builtin), Bash sends a SIGHUP to all jobs when +an interactive login shell exits. +

+ +If Bash is waiting for a command to complete and receives a signal +for which a trap has been set, the trap will not be executed until +the command completes. +When Bash is waiting for an asynchronous +command via the wait builtin, the reception of a signal for +which a trap has been set will cause the wait builtin to return +immediately with an exit status greater than 128, immediately after +which the trap is executed. +

+ + +

+ + + + + + + + + + + +
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+

3.8 Shell Scripts

+ +

+ +A shell script is a text file containing shell commands. When such +a file is used as the first non-option argument when invoking Bash, +and neither the `-c' nor `-s' option is supplied +(see section 6.1 Invoking Bash), +Bash reads and executes commands from the file, then exits. This +mode of operation creates a non-interactive shell. The shell first +searches for the file in the current directory, and looks in the +directories in $PATH if not found there. +

+ +When Bash runs +a shell script, it sets the special parameter 0 to the name +of the file, rather than the name of the shell, and the positional +parameters are set to the remaining arguments, if any are given. +If no additional arguments are supplied, the positional parameters +are unset. +

+ +A shell script may be made executable by using the chmod command +to turn on the execute bit. When Bash finds such a file while +searching the $PATH for a command, it spawns a subshell to +execute it. In other words, executing +
 
filename arguments
+
is equivalent to executing +
 
bash filename arguments
+

+ +if filename is an executable shell script. +This subshell reinitializes itself, so that the effect is as if a +new shell had been invoked to interpret the script, with the +exception that the locations of commands remembered by the parent +(see the description of hash in 4.1 Bourne Shell Builtins) +are retained by the child. +

+ +Most versions of Unix make this a part of the operating system's command +execution mechanism. If the first line of a script begins with +the two characters `#!', the remainder of the line specifies +an interpreter for the program. +Thus, you can specify Bash, awk, Perl, or some other +interpreter and write the rest of the script file in that language. +

+ +The arguments to the interpreter +consist of a single optional argument following the interpreter +name on the first line of the script file, followed by the name of +the script file, followed by the rest of the arguments. Bash +will perform this action on operating systems that do not handle it +themselves. Note that some older versions of Unix limit the interpreter +name and argument to a maximum of 32 characters. +

+ +Bash scripts often begin with #! /bin/bash (assuming that +Bash has been installed in `/bin'), since this ensures that +Bash will be used to interpret the script, even if it is executed +under another shell. +

+ + +

+ + + + + + + + + + + +
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+

4. Shell Builtin Commands

+ +

+ +

+ + + + +
4.1 Bourne Shell Builtins  Builtin commands inherited from the Bourne + Shell.
4.2 Bash Builtin Commands  Table of builtins specific to Bash.
4.3 Modifying Shell Behavior  Builtins to modify shell attributes and + optional behavior.
4.4 Special Builtins  Builtin commands classified specially by + POSIX.
+

+ +Builtin commands are contained within the shell itself. +When the name of a builtin command is used as the first word of +a simple command (see section 3.2.1 Simple Commands), the shell executes +the command directly, without invoking another program. +Builtin commands are necessary to implement functionality impossible +or inconvenient to obtain with separate utilities. +

+ +This section briefly describes the builtins which Bash inherits from +the Bourne Shell, as well as the builtin commands which are unique +to or have been extended in Bash. +

+ +Several builtin commands are described in other chapters: builtin +commands which provide the Bash interface to the job control +facilities (see section 7.2 Job Control Builtins), the directory stack +(see section 6.8.1 Directory Stack Builtins), the command history +(see section 9.2 Bash History Builtins), and the programmable completion +facilities (see section 8.7 Programmable Completion Builtins). +

+ +Many of the builtins have been extended by POSIX or Bash. +

+ +Unless otherwise noted, each builtin command documented as accepting +options preceded by `-' accepts `--' +to signify the end of the options. +For example, the :, true, false, and test +builtins do not accept options. +

+ + +

+ + + + + + + + + + + +
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+

4.1 Bourne Shell Builtins

+ +

+ +The following shell builtin commands are inherited from the Bourne Shell. +These commands are implemented as specified by the POSIX standard. +

+ +

+
: (a colon) +
+
 
: [arguments]
+
Do nothing beyond expanding arguments and performing redirections. +The return status is zero. +

+ +

. (a period) +
+
 
. filename [arguments]
+
Read and execute commands from the filename argument in the +current shell context. If filename does not contain a slash, +the PATH variable is used to find filename. +When Bash is not in POSIX mode, the current directory is searched +if filename is not found in $PATH. +If any arguments are supplied, they become the positional +parameters when filename is executed. Otherwise the positional +parameters are unchanged. +The return status is the exit status of the last command executed, or +zero if no commands are executed. If filename is not found, or +cannot be read, the return status is non-zero. +This builtin is equivalent to source. +

+ +

break +
+
 
break [n]
+
Exit from a for, while, until, or select loop. +If n is supplied, the nth enclosing loop is exited. +n must be greater than or equal to 1. +The return status is zero unless n is not greater than or equal to 1. +

+ +

cd +
+
 
cd [-L|-P] [directory]
+
Change the current working directory to directory. +If directory is not given, the value of the HOME shell +variable is used. +If the shell variable CDPATH exists, it is used as a search path. +If directory begins with a slash, CDPATH is not used. +

+ +The `-P' option means to not follow symbolic links; symbolic +links are followed by default or with the `-L' option. +If directory is `-', it is equivalent to $OLDPWD. +

+ +If a non-empty directory name from CDPATH is used, or if +`-' is the first argument, and the directory change is +successful, the absolute pathname of the new working directory is +written to the standard output. +

+ +The return status is zero if the directory is successfully changed, +non-zero otherwise. +

+ +

continue +
+
 
continue [n]
+
Resume the next iteration of an enclosing for, while, +until, or select loop. +If n is supplied, the execution of the nth enclosing loop +is resumed. +n must be greater than or equal to 1. +The return status is zero unless n is not greater than or equal to 1. +

+ +

eval +
+
 
eval [arguments]
+
The arguments are concatenated together into a single command, which is +then read and executed, and its exit status returned as the exit status +of eval. +If there are no arguments or only empty arguments, the return status is +zero. +

+ +

exec +
+
 
exec [-cl] [-a name] [command [arguments]]
+
If command +is supplied, it replaces the shell without creating a new process. +If the `-l' option is supplied, the shell places a dash at the +beginning of the zeroth argument passed to command. +This is what the login program does. +The `-c' option causes command to be executed with an empty +environment. +If `-a' is supplied, the shell passes name as the zeroth +argument to command. +If no command is specified, redirections may be used to affect +the current shell environment. If there are no redirection errors, the +return status is zero; otherwise the return status is non-zero. +

+ +

exit +
+
 
exit [n]
+
Exit the shell, returning a status of n to the shell's parent. +If n is omitted, the exit status is that of the last command executed. +Any trap on EXIT is executed before the shell terminates. +

+ +

export +
+
 
export [-fn] [-p] [name[=value]]
+
Mark each name to be passed to child processes +in the environment. If the `-f' option is supplied, the names +refer to shell functions; otherwise the names refer to shell variables. +The `-n' option means to no longer mark each name for export. +If no names are supplied, or if the `-p' option is given, a +list of exported names is displayed. +The `-p' option displays output in a form that may be reused as input. +If a variable name is followed by =value, the value of +the variable is set to value. +

+ +The return status is zero unless an invalid option is supplied, one of +the names is not a valid shell variable name, or `-f' is supplied +with a name that is not a shell function. +

+ +

getopts +
+
 
getopts optstring name [args]
+
getopts is used by shell scripts to parse positional parameters. +optstring contains the option characters to be recognized; if a +character is followed by a colon, the option is expected to have an +argument, which should be separated from it by white space. +The colon (`:') and question mark (`?') may not be +used as option characters. +Each time it is invoked, getopts +places the next option in the shell variable name, initializing +name if it does not exist, +and the index of the next argument to be processed into the +variable OPTIND. +OPTIND is initialized to 1 each time the shell or a shell script +is invoked. +When an option requires an argument, +getopts places that argument into the variable OPTARG. +The shell does not reset OPTIND automatically; it must be manually +reset between multiple calls to getopts within the same shell +invocation if a new set of parameters is to be used. +

+ +When the end of options is encountered, getopts exits with a +return value greater than zero. +OPTIND is set to the index of the first non-option argument, +and name is set to `?'. +

+ +getopts +normally parses the positional parameters, but if more arguments are +given in args, getopts parses those instead. +

+ +getopts can report errors in two ways. If the first character of +optstring is a colon, silent +error reporting is used. In normal operation diagnostic messages +are printed when invalid options or missing option arguments are +encountered. +If the variable OPTERR +is set to 0, no error messages will be displayed, even if the first +character of optstring is not a colon. +

+ +If an invalid option is seen, +getopts places `?' into name and, if not silent, +prints an error message and unsets OPTARG. +If getopts is silent, the option character found is placed in +OPTARG and no diagnostic message is printed. +

+ +If a required argument is not found, and getopts +is not silent, a question mark (`?') is placed in name, +OPTARG is unset, and a diagnostic message is printed. +If getopts is silent, then a colon (`:') is placed in +name and OPTARG is set to the option character found. +

+ +

hash +
+
 
hash [-r] [-p filename] [-dt] [name]
+
Remember the full pathnames of commands specified as name arguments, +so they need not be searched for on subsequent invocations. +The commands are found by searching through the directories listed in +$PATH. +The `-p' option inhibits the path search, and filename is +used as the location of name. +The `-r' option causes the shell to forget all remembered locations. +The `-d' option causes the shell to forget the remembered location +of each name. +If the `-t' option is supplied, the full pathname to which each +name corresponds is printed. If multiple name arguments are +supplied with `-t' the name is printed before the hashed +full pathname. +The `-l' option causes output to be displayed in a format +that may be reused as input. +If no arguments are given, or if only `-l' is supplied, +information about remembered commands is printed. +The return status is zero unless a name is not found or an invalid +option is supplied. +

+ +

pwd +
+
 
pwd [-LP]
+
Print the absolute pathname of the current working directory. +If the `-P' option is supplied, the pathname printed will not +contain symbolic links. +If the `-L' option is supplied, the pathname printed may contain +symbolic links. +The return status is zero unless an error is encountered while +determining the name of the current directory or an invalid option +is supplied. +

+ +

readonly +
+
 
readonly [-apf] [name[=value]] ...
+
Mark each name as readonly. +The values of these names may not be changed by subsequent assignment. +If the `-f' option is supplied, each name refers to a shell +function. +The `-a' option means each name refers to an array variable. +If no name arguments are given, or if the `-p' +option is supplied, a list of all readonly names is printed. +The `-p' option causes output to be displayed in a format that +may be reused as input. +If a variable name is followed by =value, the value of +the variable is set to value. +The return status is zero unless an invalid option is supplied, one of +the name arguments is not a valid shell variable or function name, +or the `-f' option is supplied with a name that is not a shell function. +

+ +

return +
+
 
return [n]
+
Cause a shell function to exit with the return value n. +If n is not supplied, the return value is the exit status of the +last command executed in the function. +This may also be used to terminate execution of a script being executed +with the . (or source) builtin, returning either n or +the exit status of the last command executed within the script as the exit +status of the script. +Any command associated with the RETURN trap is executed +before execution resumes after the function or script. +The return status is non-zero if return is used outside a function +and not during the execution of a script by . or source. +

+ +

shift +
+
 
shift [n]
+
Shift the positional parameters to the left by n. +The positional parameters from n+1 ... $# are +renamed to $1 ... $#-n. +Parameters represented by the numbers $# to $#-n+1 +are unset. +n must be a non-negative number less than or equal to $#. +If n is zero or greater than $#, the positional parameters +are not changed. +If n is not supplied, it is assumed to be 1. +The return status is zero unless n is greater than $# or +less than zero, non-zero otherwise. +

+ +

test +
[ +
+ +Evaluate a conditional expression expr. +Each operator and operand must be a separate argument. +Expressions are composed of the primaries described below in +6.4 Bash Conditional Expressions. +test does not accept any options, nor does it accept and ignore +an argument of `--' as signifying the end of options. +

+ +When the [ form is used, the last argument to the command must +be a ]. +

+ +Expressions may be combined using the following operators, listed in +decreasing order of precedence. +

+ +

+
! expr +
True if expr is false. +

+ +

( expr ) +
Returns the value of expr. +This may be used to override the normal precedence of operators. +

+ +

expr1 -a expr2 +
True if both expr1 and expr2 are true. +

+ +

expr1 -o expr2 +
True if either expr1 or expr2 is true. +
+

+ +The test and [ builtins evaluate conditional +expressions using a set of rules based on the number of arguments. +

+ +

+
0 arguments +
The expression is false. +

+ +

1 argument +
The expression is true if and only if the argument is not null. +

+ +

2 arguments +
If the first argument is `!', the expression is true if and +only if the second argument is null. +If the first argument is one of the unary conditional operators +(see section 6.4 Bash Conditional Expressions), the expression +is true if the unary test is true. +If the first argument is not a valid unary operator, the expression is +false. +

+ +

3 arguments +
If the second argument is one of the binary conditional +operators (see section 6.4 Bash Conditional Expressions), the +result of the expression is the result of the binary test using the +first and third arguments as operands. +If the first argument is `!', the value is the negation of +the two-argument test using the second and third arguments. +If the first argument is exactly `(' and the third argument is +exactly `)', the result is the one-argument test of the second +argument. +Otherwise, the expression is false. +The `-a' and `-o' operators are considered binary operators +in this case. +

+ +

4 arguments +
If the first argument is `!', the result is the negation of +the three-argument expression composed of the remaining arguments. +Otherwise, the expression is parsed and evaluated according to +precedence using the rules listed above. +

+ +

5 or more arguments +
The expression is parsed and evaluated according to precedence +using the rules listed above. +
+

+ +

times +
+
 
times
+
Print out the user and system times used by the shell and its children. +The return status is zero. +

+ +

trap +
+
 
trap [-lp] [arg] [sigspec ...]
+
The commands in arg are to be read and executed when the +shell receives signal sigspec. If arg is absent (and +there is a single sigspec) or +equal to `-', each specified signal's disposition is reset +to the value it had when the shell was started. +If arg is the null string, then the signal specified by +each sigspec is ignored by the shell and commands it invokes. +If arg is not present and `-p' has been supplied, +the shell displays the trap commands associated with each sigspec. +If no arguments are supplied, or +only `-p' is given, trap prints the list of commands +associated with each signal number in a form that may be reused as +shell input. +The `-l' option causes the shell to print a list of signal names +and their corresponding numbers. +Each sigspec is either a signal name or a signal number. +Signal names are case insensitive and the SIG prefix is optional. +If a sigspec +is 0 or EXIT, arg is executed when the shell exits. +If a sigspec is DEBUG, the command arg is executed +before every simple command, for command, case command, +select command, every arithmetic for command, and before +the first command executes in a shell function. +Refer to the description of the extglob option to the +shopt builtin (see section 4.3.2 The Shopt Builtin) for details of its +effect on the DEBUG trap. +If a sigspec is ERR, the command arg +is executed whenever a simple command has a non-zero exit status, +subject to the following conditions. +The ERR trap is not executed if the failed command is part of the +command list immediately following an until or while keyword, +part of the test in an if statement, +part of a && or || list, or if the command's return +status is being inverted using !. +These are the same conditions obeyed by the errexit option. +If a sigspec is RETURN, the command arg is executed +each time a shell function or a script executed with the . or +source builtins finishes executing. +

+ +Signals ignored upon entry to the shell cannot be trapped or reset. +Trapped signals that are not being ignored are reset to their original +values in a child process when it is created. +

+ +The return status is zero unless a sigspec does not specify a +valid signal. +

+ +

umask +
+
 
umask [-p] [-S] [mode]
+
Set the shell process's file creation mask to mode. If +mode begins with a digit, it is interpreted as an octal number; +if not, it is interpreted as a symbolic mode mask similar +to that accepted by the chmod command. If mode is +omitted, the current value of the mask is printed. If the `-S' +option is supplied without a mode argument, the mask is printed +in a symbolic format. +If the `-p' option is supplied, and mode +is omitted, the output is in a form that may be reused as input. +The return status is zero if the mode is successfully changed or if +no mode argument is supplied, and non-zero otherwise. +

+ +Note that when the mode is interpreted as an octal number, each number +of the umask is subtracted from 7. Thus, a umask of 022 +results in permissions of 755. +

+ +

unset +
+
 
unset [-fv] [name]
+
Each variable or function name is removed. +If no options are supplied, or the `-v' option is given, each +name refers to a shell variable. +If the `-f' option is given, the names refer to shell +functions, and the function definition is removed. +Readonly variables and functions may not be unset. +The return status is zero unless a name is readonly. +
+

+ + +

+ + + + + + + + + + + +
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+

4.2 Bash Builtin Commands

+ +

+ +This section describes builtin commands which are unique to +or have been extended in Bash. +Some of these commands are specified in the POSIX standard. +

+ +

+ +
alias +
+
 
alias [-p] [name[=value] ...]
+

+ +Without arguments or with the `-p' option, alias prints +the list of aliases on the standard output in a form that allows +them to be reused as input. +If arguments are supplied, an alias is defined for each name +whose value is given. If no value is given, the name +and value of the alias is printed. +Aliases are described in 6.6 Aliases. +

+ +

bind +
+
 
bind [-m keymap] [-lpsvPSV]
+bind [-m keymap] [-q function] [-u function] [-r keyseq]
+bind [-m keymap] -f filename
+bind [-m keymap] -x keyseq:shell-command
+bind [-m keymap] keyseq:function-name
+bind readline-command
+

+ +Display current Readline (see section 8. Command Line Editing) +key and function bindings, +bind a key sequence to a Readline function or macro, +or set a Readline variable. +Each non-option argument is a command as it would appear in a +Readline initialization file (see section 8.3 Readline Init File), +but each binding or command must be passed as a separate argument; e.g., +`"\C-x\C-r":re-read-init-file'. +Options, if supplied, have the following meanings: +

+ +

+
-m keymap +
Use keymap as the keymap to be affected by +the subsequent bindings. Acceptable keymap +names are +emacs, +emacs-standard, +emacs-meta, +emacs-ctlx, +vi, +vi-move, +vi-command, and +vi-insert. +vi is equivalent to vi-command; +emacs is equivalent to emacs-standard. +

+ +

-l +
List the names of all Readline functions. +

+ +

-p +
Display Readline function names and bindings in such a way that they +can be used as input or in a Readline initialization file. +

+ +

-P +
List current Readline function names and bindings. +

+ +

-v +
Display Readline variable names and values in such a way that they +can be used as input or in a Readline initialization file. +

+ +

-V +
List current Readline variable names and values. +

+ +

-s +
Display Readline key sequences bound to macros and the strings they output +in such a way that they can be used as input or in a Readline +initialization file. +

+ +

-S +
Display Readline key sequences bound to macros and the strings they output. +

+ +

-f filename +
Read key bindings from filename. +

+ +

-q function +
Query about which keys invoke the named function. +

+ +

-u function +
Unbind all keys bound to the named function. +

+ +

-r keyseq +
Remove any current binding for keyseq. +

+ +

-x keyseq:shell-command +
Cause shell-command to be executed whenever keyseq is +entered. +

+ +

+

+ +The return status is zero unless an invalid option is supplied or an +error occurs. +

+ +

builtin +
+
 
builtin [shell-builtin [args]]
+
Run a shell builtin, passing it args, and return its exit status. +This is useful when defining a shell function with the same +name as a shell builtin, retaining the functionality of the builtin within +the function. +The return status is non-zero if shell-builtin is not a shell +builtin command. +

+ +

caller +
+
 
caller [expr]
+
Returns the context of any active subroutine call (a shell function or +a script executed with the . or source builtins). +

+ +Without expr, caller displays the line number and source +filename of the current subroutine call. +If a non-negative integer is supplied as expr, caller +displays the line number, subroutine name, and source file corresponding +to that position in the current execution call stack. This extra +information may be used, for example, to print a stack trace. The +current frame is frame 0. +

+ +The return value is 0 unless the shell is not executing a subroutine +call or expr does not correspond to a valid position in the +call stack. +

+ +

command +
+
 
command [-pVv] command [arguments ...]
+
Runs command with arguments ignoring any shell function +named command. +Only shell builtin commands or commands found by searching the +PATH are executed. +If there is a shell function named ls, running `command ls' +within the function will execute the external command ls +instead of calling the function recursively. +The `-p' option means to use a default value for PATH +that is guaranteed to find all of the standard utilities. +The return status in this case is 127 if command cannot be +found or an error occurred, and the exit status of command +otherwise. +

+ +If either the `-V' or `-v' option is supplied, a +description of command is printed. The `-v' option +causes a single word indicating the command or file name used to +invoke command to be displayed; the `-V' option produces +a more verbose description. In this case, the return status is +zero if command is found, and non-zero if not. +

+ +

declare +
+
 
declare [-afFirtx] [-p] [name[=value] ...]
+

+ +Declare variables and give them attributes. If no names +are given, then display the values of variables instead. +

+ +The `-p' option will display the attributes and values of each +name. +When `-p' is used, additional options are ignored. +The `-F' option inhibits the display of function definitions; +only the function name and attributes are printed. +If the extdebug shell option is enabled using shopt +(see section 4.3.2 The Shopt Builtin), the source file name and line number where +the function is defined are displayed as well. +`-F' implies `-f'. +The following options can be used to restrict output to variables with +the specified attributes or to give variables attributes: +

+ +

+
-a +
Each name is an array variable (see section 6.7 Arrays). +

+ +

-f +
Use function names only. +

+ +

-i +
The variable is to be treated as +an integer; arithmetic evaluation (see section 6.5 Shell Arithmetic) is +performed when the variable is assigned a value. +

+ +

-r +
Make names readonly. These names cannot then be assigned values +by subsequent assignment statements or unset. +

+ +

-t +
Give each name the trace attribute. +Traced functions inherit the DEBUG and RETURN traps from +the calling shell. +The trace attribute has no special meaning for variables. +

+ +

-x +
Mark each name for export to subsequent commands via +the environment. +
+

+ +Using `+' instead of `-' turns off the attribute instead, +with the exceptions that `+a' +may not be used to destroy an array variable and `+r' will not +remove the readonly attribute. +When used in a function, declare makes each name local, +as with the local command. If a variable name is followed by +=value, the value of the variable is set to value. +

+ +The return status is zero unless an invalid option is encountered, +an attempt is made to define a function using `-f foo=bar', +an attempt is made to assign a value to a readonly variable, +an attempt is made to assign a value to an array variable without +using the compound assignment syntax (see section 6.7 Arrays), +one of the names is not a valid shell variable name, +an attempt is made to turn off readonly status for a readonly variable, +an attempt is made to turn off array status for an array variable, +or an attempt is made to display a non-existent function with `-f'. +

+ +

echo +
+
 
echo [-neE] [arg ...]
+
Output the args, separated by spaces, terminated with a +newline. +The return status is always 0. +If `-n' is specified, the trailing newline is suppressed. +If the `-e' option is given, interpretation of the following +backslash-escaped characters is enabled. +The `-E' option disables the interpretation of these escape characters, +even on systems where they are interpreted by default. +The xpg_echo shell option may be used to +dynamically determine whether or not echo expands these +escape characters by default. +echo does not interpret `--' to mean the end of options. +

+ +echo interprets the following escape sequences: +

+
\a +
alert (bell) +
\b +
backspace +
\c +
suppress trailing newline +
\e +
escape +
\f +
form feed +
\n +
new line +
\r +
carriage return +
\t +
horizontal tab +
\v +
vertical tab +
\\ +
backslash +
\0nnn +
the eight-bit character whose value is the octal value nnn +(zero to three octal digits) +
\xHH +
the eight-bit character whose value is the hexadecimal value HH +(one or two hex digits) +
+

+ +

enable +
+
 
enable [-a] [-dnps] [-f filename] [name ...]
+
Enable and disable builtin shell commands. +Disabling a builtin allows a disk command which has the same name +as a shell builtin to be executed without specifying a full pathname, +even though the shell normally searches for builtins before disk commands. +If `-n' is used, the names become disabled. Otherwise +names are enabled. For example, to use the test binary +found via $PATH instead of the shell builtin version, type +`enable -n test'. +

+ +If the `-p' option is supplied, or no name arguments appear, +a list of shell builtins is printed. With no other arguments, the list +consists of all enabled shell builtins. +The `-a' option means to list +each builtin with an indication of whether or not it is enabled. +

+ +The `-f' option means to load the new builtin command name +from shared object filename, on systems that support dynamic loading. +The `-d' option will delete a builtin loaded with `-f'. +

+ +If there are no options, a list of the shell builtins is displayed. +The `-s' option restricts enable to the POSIX special +builtins. If `-s' is used with `-f', the new builtin becomes +a special builtin (see section 4.4 Special Builtins). +

+ +The return status is zero unless a name is not a shell builtin +or there is an error loading a new builtin from a shared object. +

+ +

help +
+
 
help [-s] [pattern]
+
Display helpful information about builtin commands. +If pattern is specified, help gives detailed help +on all commands matching pattern, otherwise a list of +the builtins is printed. +The `-s' option restricts the information displayed to a short +usage synopsis. +The return status is zero unless no command matches pattern. +

+ +

let +
+
 
let expression [expression]
+
The let builtin allows arithmetic to be performed on shell +variables. Each expression is evaluated according to the +rules given below in 6.5 Shell Arithmetic. If the +last expression evaluates to 0, let returns 1; +otherwise 0 is returned. +

+ +

local +
+
 
local [option] name[=value] ...
+
For each argument, a local variable named name is created, +and assigned value. +The option can be any of the options accepted by declare. +local can only be used within a function; it makes the variable +name have a visible scope restricted to that function and its +children. The return status is zero unless local is used outside +a function, an invalid name is supplied, or name is a +readonly variable. +

+ +

logout +
+
 
logout [n]
+
Exit a login shell, returning a status of n to the shell's +parent. +

+ +

printf +
+
 
printf [-v var] format [arguments]
+
Write the formatted arguments to the standard output under the +control of the format. +The format is a character string which contains three types of objects: +plain characters, which are simply copied to standard output, character +escape sequences, which are converted and copied to the standard output, and +format specifications, each of which causes printing of the next successive +argument. +In addition to the standard printf(1) formats, `%b' causes +printf to expand backslash escape sequences in the corresponding +argument, +(except that `\c' terminates output, backslashes in +`\'', `\"', and `\?' are not removed, and octal escapes +beginning with `\0' may contain up to four digits), +and `%q' causes printf to output the +corresponding argument in a format that can be reused as shell input. +

+ +The `-v' option causes the output to be assigned to the variable +var rather than being printed to the standard output. +

+ +The format is reused as necessary to consume all of the arguments. +If the format requires more arguments than are supplied, the +extra format specifications behave as if a zero value or null string, as +appropriate, had been supplied. The return value is zero on success, +non-zero on failure. +

+ +

read +
+
 
read [-ers] [-a aname] [-d delim] [-n nchars] [-p prompt] [-t timeout] [-u fd] [name ...]
+
One line is read from the standard input, or from the file descriptor +fd supplied as an argument to the `-u' option, and the first word +is assigned to the first name, the second word to the second name, +and so on, with leftover words and their intervening separators assigned +to the last name. +If there are fewer words read from the input stream than names, +the remaining names are assigned empty values. +The characters in the value of the IFS variable +are used to split the line into words. +The backslash character `\' may be used to remove any special +meaning for the next character read and for line continuation. +If no names are supplied, the line read is assigned to the +variable REPLY. +The return code is zero, unless end-of-file is encountered, read +times out, or an invalid file descriptor is supplied as the argument to +`-u'. +Options, if supplied, have the following meanings: +

+ +

+
-a aname +
The words are assigned to sequential indices of the array variable +aname, starting at 0. +All elements are removed from aname before the assignment. +Other name arguments are ignored. +

+ +

-d delim +
The first character of delim is used to terminate the input line, +rather than newline. +

+ +

-e +
Readline (see section 8. Command Line Editing) is used to obtain the line. +

+ +

-n nchars +
read returns after reading nchars characters rather than +waiting for a complete line of input. +

+ +

-p prompt +
Display prompt, without a trailing newline, before attempting +to read any input. +The prompt is displayed only if input is coming from a terminal. +

+ +

-r +
If this option is given, backslash does not act as an escape character. +The backslash is considered to be part of the line. +In particular, a backslash-newline pair may not be used as a line +continuation. +

+ +

-s +
Silent mode. If input is coming from a terminal, characters are +not echoed. +

+ +

-t timeout +
Cause read to time out and return failure if a complete line of +input is not read within timeout seconds. +This option has no effect if read is not reading input from the +terminal or a pipe. +

+ +

-u fd +
Read input from file descriptor fd. +

+ +

+

+ +

source +
+
 
source filename
+
A synonym for . (see section 4.1 Bourne Shell Builtins). +

+ +

type +
+
 
type [-afptP] [name ...]
+
For each name, indicate how it would be interpreted if used as a +command name. +

+ +If the `-t' option is used, type prints a single word +which is one of `alias', `function', `builtin', +`file' or `keyword', +if name is an alias, shell function, shell builtin, +disk file, or shell reserved word, respectively. +If the name is not found, then nothing is printed, and +type returns a failure status. +

+ +If the `-p' option is used, type either returns the name +of the disk file that would be executed, or nothing if `-t' +would not return `file'. +

+ +The `-P' option forces a path search for each name, even if +`-t' would not return `file'. +

+ +If a command is hashed, `-p' and `-P' print the hashed value, +not necessarily the file that appears first in $PATH. +

+ +If the `-a' option is used, type returns all of the places +that contain an executable named file. +This includes aliases and functions, if and only if the `-p' option +is not also used. +

+ +If the `-f' option is used, type does not attempt to find +shell functions, as with the command builtin. +

+ +The return status is zero if any of the names are found, non-zero +if none are found. +

+ +

typeset +
+
 
typeset [-afFrxi] [-p] [name[=value] ...]
+
The typeset command is supplied for compatibility with the Korn +shell; however, it has been deprecated in favor of the declare +builtin command. +

+ +

ulimit +
+
 
ulimit [-acdefilmnpqrstuvxSH] [limit]
+
ulimit provides control over the resources available to processes +started by the shell, on systems that allow such control. If an +option is given, it is interpreted as follows: +
+
-S +
Change and report the soft limit associated with a resource. +

+ +

-H +
Change and report the hard limit associated with a resource. +

+ +

-a +
All current limits are reported. +

+ +

-c +
The maximum size of core files created. +

+ +

-d +
The maximum size of a process's data segment. +

+ +

-e +
The maximum scheduling priority ("nice"). +

+ +

-f +
The maximum size of files written by the shell and its children. +

+ +

-i +
The maximum number of pending signals. +

+ +

-l +
The maximum size that may be locked into memory. +

+ +

-m +
The maximum resident set size. +

+ +

-n +
The maximum number of open file descriptors. +

+ +

-p +
The pipe buffer size. +

+ +

-q +
The maximum number of bytes in POSIX message queues. +

+ +

-r +
The maximum real-time scheduling priority. +

+ +

-s +
The maximum stack size. +

+ +

-t +
The maximum amount of cpu time in seconds. +

+ +

-u +
The maximum number of processes available to a single user. +

+ +

-v +
The maximum amount of virtual memory available to the process. +

+ +

-x +
The maximum number of file locks. +

+ +

+

+ +If limit is given, it is the new value of the specified resource; +the special limit values hard, soft, and +unlimited stand for the current hard limit, the current soft limit, +and no limit, respectively. +Otherwise, the current value of the soft limit for the specified resource +is printed, unless the `-H' option is supplied. +When setting new limits, if neither `-H' nor `-S' is supplied, +both the hard and soft limits are set. +If no option is given, then `-f' is assumed. Values are in 1024-byte +increments, except for `-t', which is in seconds, `-p', +which is in units of 512-byte blocks, and `-n' and `-u', which +are unscaled values. +

+ +The return status is zero unless an invalid option or argument is supplied, +or an error occurs while setting a new limit. +

+ +

unalias +
+
 
unalias [-a] [name ... ]
+

+ +Remove each name from the list of aliases. If `-a' is +supplied, all aliases are removed. +Aliases are described in 6.6 Aliases. +

+ +

+

+ + +

+ + + + + + + + + + + +
[ < ][ > ]   [ << ][ Up ][ >> ]         [Top][Contents][Index][ ? ]
+

4.3 Modifying Shell Behavior

+ + +
+ + +
4.3.1 The Set Builtin  Change the values of shell attributes and + positional parameters.
4.3.2 The Shopt Builtin  Modify shell optional behavior.
+

+ + +

+ + + + + + + + + + + +
[ < ][ > ]   [ << ][ Up ][ >> ]         [Top][Contents][Index][ ? ]
+

4.3.1 The Set Builtin

+ +

+ +This builtin is so complicated that it deserves its own section. set +allows you to change the values of shell options and set the positional +parameters, or to display the names and values of shell variables. +

+ +

+
set +
+
 
set [--abefhkmnptuvxBCEHPT] [-o option] [argument ...]
+set [+abefhkmnptuvxBCEHPT] [+o option] [argument ...]
+

+ +If no options or arguments are supplied, set displays the names +and values of all shell variables and functions, sorted according to the +current locale, in a format that may be reused as input +for setting or resetting the currently-set variables. +Read-only variables cannot be reset. +In POSIX mode, only shell variables are listed. +

+ +When options are supplied, they set or unset shell attributes. +Options, if specified, have the following meanings: +

+ +

+
-a +
Mark variables and function which are modified or created for export +to the environment of subsequent commands. +

+ +

-b +
Cause the status of terminated background jobs to be reported +immediately, rather than before printing the next primary prompt. +

+ +

-e +
Exit immediately if a simple command (see section 3.2.1 Simple Commands) exits +with a non-zero status, unless the command that fails is part of the +command list immediately following a while or until keyword, +part of the test in an if statement, +part of a && or || list, +any command in a pipeline but the last, +or if the command's return status is being inverted using !. +A trap on ERR, if set, is executed before the shell exits. +

+ +

-f +
Disable file name generation (globbing). +

+ +

-h +
Locate and remember (hash) commands as they are looked up for execution. +This option is enabled by default. +

+ +

-k +
All arguments in the form of assignment statements are placed +in the environment for a command, not just those that precede +the command name. +

+ +

-m +
Job control is enabled (see section 7. Job Control). +

+ +

-n +
Read commands but do not execute them; this may be used to check a +script for syntax errors. +This option is ignored by interactive shells. +

+ +

-o option-name +

+ +Set the option corresponding to option-name: +

+ +

+
allexport +
Same as -a. +

+ +

braceexpand +
Same as -B. +

+ +

emacs +
Use an emacs-style line editing interface (see section 8. Command Line Editing). +

+ +

errexit +
Same as -e. +

+ +

errtrace +
Same as -E. +

+ +

functrace +
Same as -T. +

+ +

hashall +
Same as -h. +

+ +

histexpand +
Same as -H. +

+ +

history +
Enable command history, as described in 9.1 Bash History Facilities. +This option is on by default in interactive shells. +

+ +

ignoreeof +
An interactive shell will not exit upon reading EOF. +

+ +

keyword +
Same as -k. +

+ +

monitor +
Same as -m. +

+ +

noclobber +
Same as -C. +

+ +

noexec +
Same as -n. +

+ +

noglob +
Same as -f. +

+ +

nolog +
Currently ignored. +

+ +

notify +
Same as -b. +

+ +

nounset +
Same as -u. +

+ +

onecmd +
Same as -t. +

+ +

physical +
Same as -P. +

+ +

pipefail +
If set, the return value of a pipeline is the value of the last +(rightmost) command to exit with a non-zero status, or zero if all +commands in the pipeline exit successfully. +This option is disabled by default. +

+ +

posix +
Change the behavior of Bash where the default operation differs +from the POSIX standard to match the standard +(see section 6.11 Bash POSIX Mode). +This is intended to make Bash behave as a strict superset of that +standard. +

+ +

privileged +
Same as -p. +

+ +

verbose +
Same as -v. +

+ +

vi +
Use a vi-style line editing interface. +

+ +

xtrace +
Same as -x. +
+

+ +

-p +
Turn on privileged mode. +In this mode, the $BASH_ENV and $ENV files are not +processed, shell functions are not inherited from the environment, +and the SHELLOPTS variable, if it appears in the environment, +is ignored. +If the shell is started with the effective user (group) id not equal to the +real user (group) id, and the -p option is not supplied, these actions +are taken and the effective user id is set to the real user id. +If the -p option is supplied at startup, the effective user id is +not reset. +Turning this option off causes the effective user +and group ids to be set to the real user and group ids. +

+ +

-t +
Exit after reading and executing one command. +

+ +

-u +
Treat unset variables as an error when performing parameter expansion. +An error message will be written to the standard error, and a non-interactive +shell will exit. +

+ +

-v +
Print shell input lines as they are read. +

+ +

-x +
Print a trace of simple commands, for commands, case +commands, select commands, and arithmetic for commands +and their arguments or associated word lists after they are +expanded and before they are executed. The value of the PS4 +variable is expanded and the resultant value is printed before +the command and its expanded arguments. +

+ +

-B +
The shell will perform brace expansion (see section 3.5.1 Brace Expansion). +This option is on by default. +

+ +

-C +
Prevent output redirection using `>', `>&', and `<>' +from overwriting existing files. +

+ +

-E +
If set, any trap on ERR is inherited by shell functions, command +substitutions, and commands executed in a subshell environment. +The ERR trap is normally not inherited in such cases. +

+ +

-H +
Enable `!' style history substitution (see section 9.3 History Expansion). +This option is on by default for interactive shells. +

+ +

-P +
If set, do not follow symbolic links when performing commands such as +cd which change the current directory. The physical directory +is used instead. By default, Bash follows +the logical chain of directories when performing commands +which change the current directory. +

+ +For example, if `/usr/sys' is a symbolic link to `/usr/local/sys' +then: +
 
$ cd /usr/sys; echo $PWD
+/usr/sys
+$ cd ..; pwd
+/usr
+

+ +If set -P is on, then: +
 
$ cd /usr/sys; echo $PWD
+/usr/local/sys
+$ cd ..; pwd
+/usr/local
+

+ +

-T +
If set, any trap on DEBUG and RETURN are inherited by +shell functions, command substitutions, and commands executed +in a subshell environment. +The DEBUG and RETURN traps are normally not inherited +in such cases. +

+ +

-- +
If no arguments follow this option, then the positional parameters are +unset. Otherwise, the positional parameters are set to the +arguments, even if some of them begin with a `-'. +

+ +

- +
Signal the end of options, cause all remaining arguments +to be assigned to the positional parameters. The `-x' +and `-v' options are turned off. +If there are no arguments, the positional parameters remain unchanged. +
+

+ +Using `+' rather than `-' causes these options to be +turned off. The options can also be used upon invocation of the +shell. The current set of options may be found in $-. +

+ +The remaining N arguments are positional parameters and are +assigned, in order, to $1, $2, ... $N. +The special parameter # is set to N. +

+ +The return status is always zero unless an invalid option is supplied. +

+

+ + +

+ + + + + + + + + + + +
[ < ][ > ]   [ << ][ Up ][ >> ]         [Top][Contents][Index][ ? ]
+

4.3.2 The Shopt Builtin

+ +

+ +This builtin allows you to change additional shell optional behavior. +

+ +

+ +
shopt +
+
 
shopt [-pqsu] [-o] [optname ...]
+
Toggle the values of variables controlling optional shell behavior. +With no options, or with the `-p' option, a list of all settable +options is displayed, with an indication of whether or not each is set. +The `-p' option causes output to be displayed in a form that +may be reused as input. +Other options have the following meanings: +

+ +

+
-s +
Enable (set) each optname. +

+ +

-u +
Disable (unset) each optname. +

+ +

-q +
Suppresses normal output; the return status +indicates whether the optname is set or unset. +If multiple optname arguments are given with `-q', +the return status is zero if all optnames are enabled; +non-zero otherwise. +

+ +

-o +
Restricts the values of +optname to be those defined for the `-o' option to the +set builtin (see section 4.3.1 The Set Builtin). +
+

+ +If either `-s' or `-u' +is used with no optname arguments, the display is limited to +those options which are set or unset, respectively. +

+ +Unless otherwise noted, the shopt options are disabled (off) +by default. +

+ +The return status when listing options is zero if all optnames +are enabled, non-zero otherwise. When setting or unsetting options, +the return status is zero unless an optname is not a valid shell +option. +

+ +The list of shopt options is: +

+ +
autocd +
If set, a command name that is the name of a directory is executed as if +it were the argument to the cd command. +This option is only used by interactive shells. +

+ +

cdable_vars +
If this is set, an argument to the cd builtin command that +is not a directory is assumed to be the name of a variable whose +value is the directory to change to. +

+ +

cdspell +
If set, minor errors in the spelling of a directory component in a +cd command will be corrected. +The errors checked for are transposed characters, +a missing character, and a character too many. +If a correction is found, the corrected path is printed, +and the command proceeds. +This option is only used by interactive shells. +

+ +

checkhash +
If this is set, Bash checks that a command found in the hash +table exists before trying to execute it. If a hashed command no +longer exists, a normal path search is performed. +

+ +

checkjobs +
If set, Bash lists the status of any stopped and running jobs before +exiting an interactive shell. If any jobs are running, this causes +the exit to be deferred until a second exit is attempted without an +intervening command (see section 7. Job Control). +The shell always postpones exiting if any jobs are stopped. +

+ +

checkwinsize +
If set, Bash checks the window size after each command +and, if necessary, updates the values of +LINES and COLUMNS. +

+ +

cmdhist +
If set, Bash +attempts to save all lines of a multiple-line +command in the same history entry. This allows +easy re-editing of multi-line commands. +

+ +

dotglob +
If set, Bash includes filenames beginning with a `.' in +the results of filename expansion. +

+ +

execfail +
If this is set, a non-interactive shell will not exit if +it cannot execute the file specified as an argument to the exec +builtin command. An interactive shell does not exit if exec +fails. +

+ +

expand_aliases +
If set, aliases are expanded as described below under Aliases, +6.6 Aliases. +This option is enabled by default for interactive shells. +

+ +

extdebug +
If set, behavior intended for use by debuggers is enabled: +

+ +

    +
  1. +The `-F' option to the declare builtin (see section 4.2 Bash Builtin Commands) +displays the source file name and line number corresponding to each function +name supplied as an argument. +

    + +

  2. +If the command run by the DEBUG trap returns a non-zero value, the +next command is skipped and not executed. +

    + +

  3. +If the command run by the DEBUG trap returns a value of 2, and the +shell is executing in a subroutine (a shell function or a shell script +executed by the . or source builtins), a call to +return is simulated. +

    + +

  4. +BASH_ARGC and BASH_ARGV are updated as described in their +descriptions (see section 5.2 Bash Variables). +

    + +

  5. +Function tracing is enabled: command substitution, shell functions, and +subshells invoked with ( command ) inherit the +DEBUG and RETURN traps. +

    + +

  6. +Error tracing is enabled: command substitution, shell functions, and +subshells invoked with ( command ) inherit the +ERROR trap. +
+

+ +

extglob +
If set, the extended pattern matching features described above +(see section 3.5.8.1 Pattern Matching) are enabled. +

+ +

extquote +
If set, $'string' and $"string" quoting is +performed within ${parameter} expansions +enclosed in double quotes. This option is enabled by default. +

+ +

failglob +
If set, patterns which fail to match filenames during pathname expansion +result in an expansion error. +

+ +

force_fignore +
If set, the suffixes specified by the FIGNORE shell variable +cause words to be ignored when performing word completion even if +the ignored words are the only possible completions. +See section 5.2 Bash Variables, for a description of FIGNORE. +This option is enabled by default. +

+ +

gnu_errfmt +
If set, shell error messages are written in the standard GNU error +message format. +

+ +

histappend +
If set, the history list is appended to the file named by the value +of the HISTFILE +variable when the shell exits, rather than overwriting the file. +

+ +

histreedit +
If set, and Readline +is being used, a user is given the opportunity to re-edit a +failed history substitution. +

+ +

histverify +
If set, and Readline +is being used, the results of history substitution are not immediately +passed to the shell parser. Instead, the resulting line is loaded into +the Readline editing buffer, allowing further modification. +

+ +

hostcomplete +
If set, and Readline is being used, Bash will attempt to perform +hostname completion when a word containing a `@' is being +completed (see section 8.4.6 Letting Readline Type For You). This option is enabled +by default. +

+ +

huponexit +
If set, Bash will send SIGHUP to all jobs when an interactive +login shell exits (see section 3.7.6 Signals). +

+ +

interactive_comments +
Allow a word beginning with `#' +to cause that word and all remaining characters on that +line to be ignored in an interactive shell. +This option is enabled by default. +

+ +

lithist +
If enabled, and the cmdhist +option is enabled, multi-line commands are saved to the history with +embedded newlines rather than using semicolon separators where possible. +

+ +

login_shell +
The shell sets this option if it is started as a login shell +(see section 6.1 Invoking Bash). +The value may not be changed. +

+ +

mailwarn +
If set, and a file that Bash is checking for mail has been +accessed since the last time it was checked, the message +"The mail in mailfile has been read" is displayed. +

+ +

no_empty_cmd_completion +
If set, and Readline is being used, Bash will not attempt to search +the PATH for possible completions when completion is attempted +on an empty line. +

+ +

nocaseglob +
If set, Bash matches filenames in a case-insensitive fashion when +performing filename expansion. +

+ +

nocasematch +
If set, Bash matches patterns in a case-insensitive fashion when +performing matching while executing case or [[ +conditional commands. +

+ +

nullglob +
If set, Bash allows filename patterns which match no +files to expand to a null string, rather than themselves. +

+ +

progcomp +
If set, the programmable completion facilities +(see section 8.6 Programmable Completion) are enabled. +This option is enabled by default. +

+ +

promptvars +
If set, prompt strings undergo +parameter expansion, command substitution, arithmetic +expansion, and quote removal after being expanded +as described below (see section 6.9 Controlling the Prompt). +This option is enabled by default. +

+ +

restricted_shell +
The shell sets this option if it is started in restricted mode +(see section 6.10 The Restricted Shell). +The value may not be changed. +This is not reset when the startup files are executed, allowing +the startup files to discover whether or not a shell is restricted. +

+ +

shift_verbose +
If this is set, the shift +builtin prints an error message when the shift count exceeds the +number of positional parameters. +

+ +

sourcepath +
If set, the source builtin uses the value of PATH +to find the directory containing the file supplied as an argument. +This option is enabled by default. +

+ +

xpg_echo +
If set, the echo builtin expands backslash-escape sequences +by default. +

+ +

+

+ +The return status when listing options is zero if all optnames +are enabled, non-zero otherwise. +When setting or unsetting options, the return status is zero unless an +optname is not a valid shell option. +

+ +

+

+ + +

+ + + + + + + + + + + +
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+

4.4 Special Builtins

+ +

+ +For historical reasons, the POSIX standard has classified +several builtin commands as special. +When Bash is executing in POSIX mode, the special builtins +differ from other builtin commands in three respects: +

+ +

    +
  1. +Special builtins are found before shell functions during command lookup. +

    + +

  2. +If a special builtin returns an error status, a non-interactive shell exits. +

    + +

  3. +Assignment statements preceding the command stay in effect in the shell +environment after the command completes. +
+

+ +When Bash is not executing in POSIX mode, these builtins behave no +differently than the rest of the Bash builtin commands. +The Bash POSIX mode is described in 6.11 Bash POSIX Mode. +

+ +These are the POSIX special builtins: +
 
break : . continue eval exec exit export readonly return set
+shift trap unset
+

+ + +

+ + + + + + + + + + + +
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+

5. Shell Variables

+ +

+ +

+ + +
5.1 Bourne Shell Variables  Variables which Bash uses in the same way + as the Bourne Shell.
5.2 Bash Variables  List of variables that exist in Bash.
+

+ +This chapter describes the shell variables that Bash uses. +Bash automatically assigns default values to a number of variables. +

+ + +

+ + + + + + + + + + + +
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+

5.1 Bourne Shell Variables

+ +

+ +Bash uses certain shell variables in the same way as the Bourne shell. +In some cases, Bash assigns a default value to the variable. +

+ +

+ + +
CDPATH +
+A colon-separated list of directories used as a search path for +the cd builtin command. +

+ + +

HOME +
+The current user's home directory; the default for the cd builtin +command. +The value of this variable is also used by tilde expansion +(see section 3.5.2 Tilde Expansion). +

+ + +

IFS +
+A list of characters that separate fields; used when the shell splits +words as part of expansion. +

+ + +

MAIL +
+If this parameter is set to a filename and the MAILPATH variable +is not set, Bash informs the user of the arrival of mail in +the specified file. +

+ + +

MAILPATH +
+A colon-separated list of filenames which the shell periodically checks +for new mail. +Each list entry can specify the message that is printed when new mail +arrives in the mail file by separating the file name from the message with +a `?'. +When used in the text of the message, $_ expands to the name of +the current mail file. +

+ + +

OPTARG +
+The value of the last option argument processed by the getopts builtin. +

+ + +

OPTIND +
+The index of the last option argument processed by the getopts builtin. +

+ + +

PATH +
+A colon-separated list of directories in which the shell looks for +commands. +A zero-length (null) directory name in the value of PATH indicates the +current directory. +A null directory name may appear as two adjacent colons, or as an initial +or trailing colon. +

+ + +

PS1 +
+The primary prompt string. The default value is `\s-\v\$ '. +See section 6.9 Controlling the Prompt, for the complete list of escape +sequences that are expanded before PS1 is displayed. +

+ + +

PS2 +
+The secondary prompt string. The default value is `> '. +

+ +

+

+ + +

+ + + + + + + + + + + +
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+

5.2 Bash Variables

+ +

+ +These variables are set or used by Bash, but other shells +do not normally treat them specially. +

+ +A few variables used by Bash are described in different chapters: +variables for controlling the job control facilities +(see section 7.3 Job Control Variables). +

+ +

+ + +
BASH +
+The full pathname used to execute the current instance of Bash. +

+ + +

BASHPID +
+Expands to the process id of the current Bash process. +This differs from $$ under certain circumstances, such as subshells +that do not require Bash to be re-initialized. +

+ + +

BASH_ARGC +
+An array variable whose values are the number of parameters in each +frame of the current bash execution call stack. The number of +parameters to the current subroutine (shell function or script executed +with . or source) is at the top of the stack. When a +subroutine is executed, the number of parameters passed is pushed onto +BASH_ARGC. +The shell sets BASH_ARGC only when in extended debugging mode +(see 4.3.2 The Shopt Builtin +for a description of the extdebug option to the shopt +builtin). +

+ + +

BASH_ARGV +
+An array variable containing all of the parameters in the current bash +execution call stack. The final parameter of the last subroutine call +is at the top of the stack; the first parameter of the initial call is +at the bottom. When a subroutine is executed, the parameters supplied +are pushed onto BASH_ARGV. +The shell sets BASH_ARGV only when in extended debugging mode +(see 4.3.2 The Shopt Builtin +for a description of the extdebug option to the shopt +builtin). +

+ + +

BASH_COMMAND +
+The command currently being executed or about to be executed, unless the +shell is executing a command as the result of a trap, +in which case it is the command executing at the time of the trap. +

+ + +

BASH_ENV +
+If this variable is set when Bash is invoked to execute a shell +script, its value is expanded and used as the name of a startup file +to read before executing the script. See section 6.2 Bash Startup Files. +

+ + +

BASH_EXECUTION_STRING +
+The command argument to the `-c' invocation option. +

+ + +

BASH_LINENO +
+An array variable whose members are the line numbers in source files +corresponding to each member of FUNCNAME. +${BASH_LINENO[$i]} is the line number in the source file where +${FUNCNAME[$i]} was called. +The corresponding source file name is ${BASH_SOURCE[$i]}. +Use LINENO to obtain the current line number. +

+ + +

BASH_REMATCH +
+An array variable whose members are assigned by the `=~' binary +operator to the [[ conditional command +(see section 3.2.4.2 Conditional Constructs). +The element with index 0 is the portion of the string +matching the entire regular expression. +The element with index n is the portion of the +string matching the nth parenthesized subexpression. +This variable is read-only. +

+ + +

BASH_SOURCE +
+An array variable whose members are the source filenames corresponding +to the elements in the FUNCNAME array variable. +

+ + +

BASH_SUBSHELL +
+Incremented by one each time a subshell or subshell environment is spawned. +The initial value is 0. +

+ + +

BASH_VERSINFO +
+A readonly array variable (see section 6.7 Arrays) +whose members hold version information for this instance of Bash. +The values assigned to the array members are as follows: +

+ +

+ +
BASH_VERSINFO[0] +
The major version number (the release). +

+ +

BASH_VERSINFO[1] +
The minor version number (the version). +

+ +

BASH_VERSINFO[2] +
The patch level. +

+ +

BASH_VERSINFO[3] +
The build version. +

+ +

BASH_VERSINFO[4] +
The release status (e.g., beta1). +

+ +

BASH_VERSINFO[5] +
The value of MACHTYPE. +

+ +

+

+ + +

BASH_VERSION +
+The version number of the current instance of Bash. +

+ + +

COLUMNS +
+Used by the select builtin command to determine the terminal width +when printing selection lists. Automatically set upon receipt of a +SIGWINCH. +

+ + +

COMP_CWORD +
+An index into ${COMP_WORDS} of the word containing the current +cursor position. +This variable is available only in shell functions invoked by the +programmable completion facilities (see section 8.6 Programmable Completion). +

+ + +

COMP_LINE +
+The current command line. +This variable is available only in shell functions and external +commands invoked by the +programmable completion facilities (see section 8.6 Programmable Completion). +

+ + +

COMP_POINT +
+The index of the current cursor position relative to the beginning of +the current command. +If the current cursor position is at the end of the current command, +the value of this variable is equal to ${#COMP_LINE}. +This variable is available only in shell functions and external +commands invoked by the +programmable completion facilities (see section 8.6 Programmable Completion). +

+ + +

COMP_TYPE +
+Set to an integer value corresponding to the type of completion attempted +that caused a completion function to be called: +TAB, for normal completion, +`?', for listing completions after successive tabs, +`!', for listing alternatives on partial word completion, +`@', to list completions if the word is not unmodified, +or +`%', for menu completion. +This variable is available only in shell functions and external +commands invoked by the +programmable completion facilities (see section 8.6 Programmable Completion). +

+ + +

COMP_KEY +
+The key (or final key of a key sequence) used to invoke the current +completion function. +

+ + +

COMP_WORDBREAKS +
+The set of characters that the Readline library treats as word +separators when performing word completion. +If COMP_WORDBREAKS is unset, it loses its special properties, +even if it is subsequently reset. +

+ + +

COMP_WORDS +
+An array variable consisting of the individual +words in the current command line. +The words are split on shell metacharacters as the shell parser would +separate them. +This variable is available only in shell functions invoked by the +programmable completion facilities (see section 8.6 Programmable Completion). +

+ + +

COMPREPLY +
+An array variable from which Bash reads the possible completions +generated by a shell function invoked by the programmable completion +facility (see section 8.6 Programmable Completion). +

+ + +

DIRSTACK +
+An array variable containing the current contents of the directory stack. +Directories appear in the stack in the order they are displayed by the +dirs builtin. +Assigning to members of this array variable may be used to modify +directories already in the stack, but the pushd and popd +builtins must be used to add and remove directories. +Assignment to this variable will not change the current directory. +If DIRSTACK is unset, it loses its special properties, even if +it is subsequently reset. +

+ + +

EMACS +
+If Bash finds this variable in the environment when the shell +starts with value `t', it assumes that the shell is running in an +emacs shell buffer and disables line editing. +

+ + +

EUID +
+The numeric effective user id of the current user. This variable +is readonly. +

+ + +

FCEDIT +
+The editor used as a default by the `-e' option to the fc +builtin command. +

+ + +

FIGNORE +
+A colon-separated list of suffixes to ignore when performing +filename completion. +A file name whose suffix matches one of the entries in +FIGNORE +is excluded from the list of matched file names. A sample +value is `.o:~' +

+ + +

FUNCNAME +
+An array variable containing the names of all shell functions +currently in the execution call stack. +The element with index 0 is the name of any currently-executing +shell function. +The bottom-most element is "main". +This variable exists only when a shell function is executing. +Assignments to FUNCNAME have no effect and return an error status. +If FUNCNAME is unset, it loses its special properties, even if +it is subsequently reset. +

+ + +

GLOBIGNORE +
+A colon-separated list of patterns defining the set of filenames to +be ignored by filename expansion. +If a filename matched by a filename expansion pattern also matches one +of the patterns in GLOBIGNORE, it is removed from the list +of matches. +

+ + +

GROUPS +
+An array variable containing the list of groups of which the current +user is a member. +Assignments to GROUPS have no effect and return an error status. +If GROUPS is unset, it loses its special properties, even if it is +subsequently reset. +

+ + +

histchars +
+Up to three characters which control history expansion, quick +substitution, and tokenization (see section 9.3 History Expansion). +The first character is the +history expansion character, that is, the character which signifies the +start of a history expansion, normally `!'. The second character is the +character which signifies `quick substitution' when seen as the first +character on a line, normally `^'. The optional third character is the +character which indicates that the remainder of the line is a comment when +found as the first character of a word, usually `#'. The history +comment character causes history substitution to be skipped for the +remaining words on the line. It does not necessarily cause the shell +parser to treat the rest of the line as a comment. +

+ + +

HISTCMD +
+The history number, or index in the history list, of the current +command. If HISTCMD is unset, it loses its special properties, +even if it is subsequently reset. +

+ + +

HISTCONTROL +
+A colon-separated list of values controlling how commands are saved on +the history list. +If the list of values includes `ignorespace', lines which begin +with a space character are not saved in the history list. +A value of `ignoredups' causes lines which match the previous +history entry to not be saved. +A value of `ignoreboth' is shorthand for +`ignorespace' and `ignoredups'. +A value of `erasedups' causes all previous lines matching the +current line to be removed from the history list before that line +is saved. +Any value not in the above list is ignored. +If HISTCONTROL is unset, or does not include a valid value, +all lines read by the shell parser are saved on the history list, +subject to the value of HISTIGNORE. +The second and subsequent lines of a multi-line compound command are +not tested, and are added to the history regardless of the value of +HISTCONTROL. +

+ + +

HISTFILE +
+The name of the file to which the command history is saved. The +default value is `~/.bash_history'. +

+ + +

HISTFILESIZE +
+The maximum number of lines contained in the history file. When this +variable is assigned a value, the history file is truncated, if +necessary, by removing the oldest entries, +to contain no more than that number of lines. +The history file is also truncated to this size after +writing it when an interactive shell exits. +The default value is 500. +

+ + +

HISTIGNORE +
+A colon-separated list of patterns used to decide which command +lines should be saved on the history list. Each pattern is +anchored at the beginning of the line and must match the complete +line (no implicit `*' is appended). Each pattern is tested +against the line after the checks specified by HISTCONTROL +are applied. In addition to the normal shell pattern matching +characters, `&' matches the previous history line. `&' +may be escaped using a backslash; the backslash is removed +before attempting a match. +The second and subsequent lines of a multi-line compound command are +not tested, and are added to the history regardless of the value of +HISTIGNORE. +

+ +HISTIGNORE subsumes the function of HISTCONTROL. A +pattern of `&' is identical to ignoredups, and a +pattern of `[ ]*' is identical to ignorespace. +Combining these two patterns, separating them with a colon, +provides the functionality of ignoreboth. +

+ + +

HISTSIZE +
+The maximum number of commands to remember on the history list. +The default value is 500. +

+ + +

HISTTIMEFORMAT +
+If this variable is set and not null, its value is used as a format string +for strftime to print the time stamp associated with each history +entry displayed by the history builtin. +If this variable is set, time stamps are written to the history file so +they may be preserved across shell sessions. +

+ + +

HOSTFILE +
+Contains the name of a file in the same format as `/etc/hosts' that +should be read when the shell needs to complete a hostname. +The list of possible hostname completions may be changed while the shell +is running; +the next time hostname completion is attempted after the +value is changed, Bash adds the contents of the new file to the +existing list. +If HOSTFILE is set, but has no value, Bash attempts to read +`/etc/hosts' to obtain the list of possible hostname completions. +When HOSTFILE is unset, the hostname list is cleared. +

+ + +

HOSTNAME +
+The name of the current host. +

+ + +

HOSTTYPE +
+A string describing the machine Bash is running on. +

+ + +

IGNOREEOF +
+Controls the action of the shell on receipt of an EOF character +as the sole input. If set, the value denotes the number +of consecutive EOF characters that can be read as the +first character on an input line +before the shell will exit. If the variable exists but does not +have a numeric value (or has no value) then the default is 10. +If the variable does not exist, then EOF signifies the end of +input to the shell. This is only in effect for interactive shells. +

+ + +

INPUTRC +
+The name of the Readline initialization file, overriding the default +of `~/.inputrc'. +

+ + +

LANG +
+Used to determine the locale category for any category not specifically +selected with a variable starting with LC_. +

+ + +

LC_ALL +
+This variable overrides the value of LANG and any other +LC_ variable specifying a locale category. +

+ + +

LC_COLLATE +
+This variable determines the collation order used when sorting the +results of filename expansion, and +determines the behavior of range expressions, equivalence classes, +and collating sequences within filename expansion and pattern matching +(see section 3.5.8 Filename Expansion). +

+ + +

LC_CTYPE +
+This variable determines the interpretation of characters and the +behavior of character classes within filename expansion and pattern +matching (see section 3.5.8 Filename Expansion). +

+ + +

LC_MESSAGES +
+This variable determines the locale used to translate double-quoted +strings preceded by a `$' (see section 3.1.2.5 Locale-Specific Translation). +

+ + +

LC_NUMERIC +
+This variable determines the locale category used for number formatting. +

+ + +

LINENO +
+The line number in the script or shell function currently executing. +

+ + +

LINES +
+Used by the select builtin command to determine the column length +for printing selection lists. Automatically set upon receipt of a +SIGWINCH. +

+ + +

MACHTYPE +
+A string that fully describes the system type on which Bash +is executing, in the standard GNU cpu-company-system format. +

+ + +

MAILCHECK +
+How often (in seconds) that the shell should check for mail in the +files specified in the MAILPATH or MAIL variables. +The default is 60 seconds. When it is time to check +for mail, the shell does so before displaying the primary prompt. +If this variable is unset, or set to a value that is not a number +greater than or equal to zero, the shell disables mail checking. +

+ + +

OLDPWD +
+The previous working directory as set by the cd builtin. +

+ + +

OPTERR +
+If set to the value 1, Bash displays error messages +generated by the getopts builtin command. +

+ + +

OSTYPE +
+A string describing the operating system Bash is running on. +

+ + +

PIPESTATUS +
+An array variable (see section 6.7 Arrays) +containing a list of exit status values from the processes +in the most-recently-executed foreground pipeline (which may +contain only a single command). +

+ + +

POSIXLY_CORRECT +
+If this variable is in the environment when bash starts, the shell +enters POSIX mode (see section 6.11 Bash POSIX Mode) before reading the +startup files, as if the `--posix' invocation option had been supplied. +If it is set while the shell is running, bash enables POSIX mode, +as if the command +
 
set -o posix
+
had been executed. +

+ + +

PPID +
+The process ID of the shell's parent process. This variable +is readonly. +

+ + +

PROMPT_COMMAND +
+If set, the value is interpreted as a command to execute +before the printing of each primary prompt ($PS1). +

+ + +

PS3 +
+The value of this variable is used as the prompt for the +select command. If this variable is not set, the +select command prompts with `#? ' +

+ + +

PS4 +
+The value is the prompt printed before the command line is echoed +when the `-x' option is set (see section 4.3.1 The Set Builtin). +The first character of PS4 is replicated multiple times, as +necessary, to indicate multiple levels of indirection. +The default is `+ '. +

+ + +

PWD +
+The current working directory as set by the cd builtin. +

+ + +

RANDOM +
+Each time this parameter is referenced, a random integer +between 0 and 32767 is generated. Assigning a value to this +variable seeds the random number generator. +

+ + +

REPLY +
+The default variable for the read builtin. +

+ + +

SECONDS +
+This variable expands to the number of seconds since the +shell was started. Assignment to this variable resets +the count to the value assigned, and the expanded value +becomes the value assigned plus the number of seconds +since the assignment. +

+ + +

SHELL +
+The full pathname to the shell is kept in this environment variable. +If it is not set when the shell starts, +Bash assigns to it the full pathname of the current user's login shell. +

+ + +

SHELLOPTS +
+A colon-separated list of enabled shell options. Each word in +the list is a valid argument for the `-o' option to the +set builtin command (see section 4.3.1 The Set Builtin). +The options appearing in SHELLOPTS are those reported +as `on' by `set -o'. +If this variable is in the environment when Bash +starts up, each shell option in the list will be enabled before +reading any startup files. This variable is readonly. +

+ + +

SHLVL +
+Incremented by one each time a new instance of Bash is started. This is +intended to be a count of how deeply your Bash shells are nested. +

+ + +

TIMEFORMAT +
+The value of this parameter is used as a format string specifying +how the timing information for pipelines prefixed with the time +reserved word should be displayed. +The `%' character introduces an +escape sequence that is expanded to a time value or other +information. +The escape sequences and their meanings are as +follows; the braces denote optional portions. +

+ +

+ +
%% +
A literal `%'. +

+ +

%[p][l]R +
The elapsed time in seconds. +

+ +

%[p][l]U +
The number of CPU seconds spent in user mode. +

+ +

%[p][l]S +
The number of CPU seconds spent in system mode. +

+ +

%P +
The CPU percentage, computed as (%U + %S) / %R. +
+

+ +The optional p is a digit specifying the precision, the number of +fractional digits after a decimal point. +A value of 0 causes no decimal point or fraction to be output. +At most three places after the decimal point may be specified; values +of p greater than 3 are changed to 3. +If p is not specified, the value 3 is used. +

+ +The optional l specifies a longer format, including minutes, of +the form MMmSS.FFs. +The value of p determines whether or not the fraction is included. +

+ +If this variable is not set, Bash acts as if it had the value +
 
$'\nreal\t%3lR\nuser\t%3lU\nsys\t%3lS'
+
If the value is null, no timing information is displayed. +A trailing newline is added when the format string is displayed. +

+ + +

TMOUT +
+If set to a value greater than zero, TMOUT is treated as the +default timeout for the read builtin (see section 4.2 Bash Builtin Commands). +The select command (see section 3.2.4.2 Conditional Constructs) terminates +if input does not arrive after TMOUT seconds when input is coming +from a terminal. +

+ +In an interactive shell, the value is interpreted as +the number of seconds to wait for input after issuing the primary +prompt when the shell is interactive. +Bash terminates after that number of seconds if input does +not arrive. +

+ + +

TMPDIR +
+If set, Bash uses its value as the name of a directory in which +Bash creates temporary files for the shell's use. +

+ + +

UID +
+The numeric real user id of the current user. This variable is readonly. +

+ +

+

+ + +

+ + + + + + + + + + + +
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+

6. Bash Features

+ +

+ +This section describes features unique to Bash. +

+ +

+ + + + + + + + + + + +
6.1 Invoking Bash  Command line options that you can give + to Bash.
6.2 Bash Startup Files  When and how Bash executes scripts.
6.3 Interactive Shells  What an interactive shell is.
6.4 Bash Conditional Expressions  Primitives used in composing expressions for + the test builtin.
6.5 Shell Arithmetic  Arithmetic on shell variables.
6.6 Aliases  Substituting one command for another.
6.7 Arrays  Array Variables.
6.8 The Directory Stack  History of visited directories.
6.9 Controlling the Prompt  Controlling the PS1 string.
6.10 The Restricted Shell  A more controlled mode of shell execution.
6.11 Bash POSIX Mode  Making Bash behave more closely to what + the POSIX standard specifies.
+

+ + +

+ + + + + + + + + + + +
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+

6.1 Invoking Bash

+ +

+ +
 
bash [long-opt] [-ir] [-abefhkmnptuvxdBCDHP] [-o option] [-O shopt_option] [argument ...]
+bash [long-opt] [-abefhkmnptuvxdBCDHP] [-o option] [-O shopt_option] -c string [argument ...]
+bash [long-opt] -s [-abefhkmnptuvxdBCDHP] [-o option] [-O shopt_option] [argument ...]
+

+ +In addition to the single-character shell command-line options +(see section 4.3.1 The Set Builtin), there are several multi-character +options that you can use. These options must appear on the command +line before the single-character options to be recognized. +

+ +

+
--debugger +
Arrange for the debugger profile to be executed before the shell +starts. Turns on extended debugging mode (see 4.3.2 The Shopt Builtin +for a description of the extdebug option to the shopt +builtin) and shell function tracing +(see 4.3.1 The Set Builtin for a description of the -o functrace +option). +

+ +

--dump-po-strings +
A list of all double-quoted strings preceded by `$' +is printed on the standard output +in the GNU gettext PO (portable object) file format. +Equivalent to `-D' except for the output format. +

+ +

--dump-strings +
Equivalent to `-D'. +

+ +

--help +
Display a usage message on standard output and exit successfully. +

+ +

--init-file filename +
--rcfile filename +
Execute commands from filename (instead of `~/.bashrc') +in an interactive shell. +

+ +

--login +
Equivalent to `-l'. +

+ +

--noediting +
Do not use the GNU Readline library (see section 8. Command Line Editing) +to read command lines when the shell is interactive. +

+ +

--noprofile +
Don't load the system-wide startup file `/etc/profile' +or any of the personal initialization files +`~/.bash_profile', `~/.bash_login', or `~/.profile' +when Bash is invoked as a login shell. +

+ +

--norc +
Don't read the `~/.bashrc' initialization file in an +interactive shell. This is on by default if the shell is +invoked as sh. +

+ +

--posix +
Change the behavior of Bash where the default operation differs +from the POSIX standard to match the standard. This +is intended to make Bash behave as a strict superset of that +standard. See section 6.11 Bash POSIX Mode, for a description of the Bash +POSIX mode. +

+ +

--restricted +
Make the shell a restricted shell (see section 6.10 The Restricted Shell). +

+ +

--verbose +
Equivalent to `-v'. Print shell input lines as they're read. +

+ +

--version +
Show version information for this instance of +Bash on the standard output and exit successfully. +

+ +

+

+ +There are several single-character options that may be supplied at +invocation which are not available with the set builtin. +

+ +

+
-c string +
Read and execute commands from string after processing the +options, then exit. Any remaining arguments are assigned to the +positional parameters, starting with $0. +

+ +

-i +
Force the shell to run interactively. Interactive shells are +described in 6.3 Interactive Shells. +

+ +

-l +
Make this shell act as if it had been directly invoked by login. +When the shell is interactive, this is equivalent to starting a +login shell with `exec -l bash'. +When the shell is not interactive, the login shell startup files will +be executed. +`exec bash -l' or `exec bash --login' +will replace the current shell with a Bash login shell. +See section 6.2 Bash Startup Files, for a description of the special behavior +of a login shell. +

+ +

-r +
Make the shell a restricted shell (see section 6.10 The Restricted Shell). +

+ +

-s +
If this option is present, or if no arguments remain after option +processing, then commands are read from the standard input. +This option allows the positional parameters to be set +when invoking an interactive shell. +

+ +

-D +
A list of all double-quoted strings preceded by `$' +is printed on the standard output. +These are the strings that +are subject to language translation when the current locale +is not C or POSIX (see section 3.1.2.5 Locale-Specific Translation). +This implies the `-n' option; no commands will be executed. +

+ +

[-+]O [shopt_option] +
shopt_option is one of the shell options accepted by the +shopt builtin (see section 4.3.2 The Shopt Builtin). +If shopt_option is present, `-O' sets the value of that option; +`+O' unsets it. +If shopt_option is not supplied, the names and values of the shell +options accepted by shopt are printed on the standard output. +If the invocation option is `+O', the output is displayed in a format +that may be reused as input. +

+ +

-- +
A -- signals the end of options and disables further option +processing. +Any arguments after the -- are treated as filenames and arguments. +

+ +

+

+ + +A login shell is one whose first character of argument zero is +`-', or one invoked with the `--login' option. +

+ + +An interactive shell is one started without non-option arguments, +unless `-s' is specified, +without specifying the `-c' option, and whose input and output are both +connected to terminals (as determined by isatty(3)), or one +started with the `-i' option. See section 6.3 Interactive Shells, for more +information. +

+ +If arguments remain after option processing, and neither the +`-c' nor the `-s' +option has been supplied, the first argument is assumed to +be the name of a file containing shell commands (see section 3.8 Shell Scripts). +When Bash is invoked in this fashion, $0 +is set to the name of the file, and the positional parameters +are set to the remaining arguments. +Bash reads and executes commands from this file, then exits. +Bash's exit status is the exit status of the last command executed +in the script. If no commands are executed, the exit status is 0. +

+ + +

+ + + + + + + + + + + +
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+

6.2 Bash Startup Files

+ +

+ +This section describes how Bash executes its startup files. +If any of the files exist but cannot be read, Bash reports an error. +Tildes are expanded in file names as described above under +Tilde Expansion (see section 3.5.2 Tilde Expansion). +

+ +Interactive shells are described in 6.3 Interactive Shells. +

+ + +

Invoked as an interactive login shell, or with `--login'

+ +

+ +When Bash is invoked as an interactive login shell, or as a +non-interactive shell with the `--login' option, it first reads and +executes commands from the file `/etc/profile', if that file exists. +After reading that file, it looks for `~/.bash_profile', +`~/.bash_login', and `~/.profile', in that order, and reads +and executes commands from the first one that exists and is readable. +The `--noprofile' option may be used when the shell is started to +inhibit this behavior. +

+ +When a login shell exits, Bash reads and executes commands from +the file `~/.bash_logout', if it exists. +

+ + +

Invoked as an interactive non-login shell

+ +

+ +When an interactive shell that is not a login shell is started, Bash +reads and executes commands from `~/.bashrc', if that file exists. +This may be inhibited by using the `--norc' option. +The `--rcfile file' option will force Bash to read and +execute commands from file instead of `~/.bashrc'. +

+ +So, typically, your `~/.bash_profile' contains the line +
 
if [ -f ~/.bashrc ]; then . ~/.bashrc; fi
+
after (or before) any login-specific initializations. +

+ + +

Invoked non-interactively

+ +

+ +When Bash is started non-interactively, to run a shell script, +for example, it looks for the variable BASH_ENV in the environment, +expands its value if it appears there, and uses the expanded value as +the name of a file to read and execute. Bash behaves as if the +following command were executed: +
 
if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi
+
but the value of the PATH variable is not used to search for the +file name. +

+ +As noted above, if a non-interactive shell is invoked with the +`--login' option, Bash attempts to read and execute commands from the +login shell startup files. +

+ + +

Invoked with name sh

+ +

+ +If Bash is invoked with the name sh, it tries to mimic the +startup behavior of historical versions of sh as closely as +possible, while conforming to the POSIX standard as well. +

+ +When invoked as an interactive login shell, or as a non-interactive +shell with the `--login' option, it first attempts to read +and execute commands from `/etc/profile' and `~/.profile', in +that order. +The `--noprofile' option may be used to inhibit this behavior. +When invoked as an interactive shell with the name sh, Bash +looks for the variable ENV, expands its value if it is defined, +and uses the expanded value as the name of a file to read and execute. +Since a shell invoked as sh does not attempt to read and execute +commands from any other startup files, the `--rcfile' option has +no effect. +A non-interactive shell invoked with the name sh does not attempt +to read any other startup files. +

+ +When invoked as sh, Bash enters POSIX mode after +the startup files are read. +

+ + +

Invoked in POSIX mode

+ +

+ +When Bash is started in POSIX mode, as with the +`--posix' command line option, it follows the POSIX standard +for startup files. +In this mode, interactive shells expand the ENV variable +and commands are read and executed from the file whose name is the +expanded value. +No other startup files are read. +

+ + +

Invoked by remote shell daemon

+ +

+ +Bash attempts to determine when it is being run by the remote shell +daemon, usually rshd. If Bash determines it is being run by +rshd, it reads and executes commands from `~/.bashrc', if that +file exists and is readable. +It will not do this if invoked as sh. +The `--norc' option may be used to inhibit this behavior, and the +`--rcfile' option may be used to force another file to be read, but +rshd does not generally invoke the shell with those options or +allow them to be specified. +

+ + +

Invoked with unequal effective and real UID/GIDs

+ +

+ +If Bash is started with the effective user (group) id not equal to the +real user (group) id, and the -p option is not supplied, no startup +files are read, shell functions are not inherited from the environment, +the SHELLOPTS variable, if it appears in the environment, is ignored, +and the effective user id is set to the real user id. +If the -p option is supplied at invocation, the startup behavior is +the same, but the effective user id is not reset. +

+ + +

+ + + + + + + + + + + +
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+

6.3 Interactive Shells

+ +

+ +

+ + + +
6.3.1 What is an Interactive Shell?  What determines whether a shell is Interactive.
6.3.2 Is this Shell Interactive?  How to tell if a shell is interactive.
6.3.3 Interactive Shell Behavior  What changes in a interactive shell?
+

+ + +

+ + + + + + + + + + + +
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+

6.3.1 What is an Interactive Shell?

+ +

+ +An interactive shell +is one started without non-option arguments, unless `-s' is +specified, without specifying the `-c' option, and +whose input and error output are both +connected to terminals (as determined by isatty(3)), +or one started with the `-i' option. +

+ +An interactive shell generally reads from and writes to a user's +terminal. +

+ +The `-s' invocation option may be used to set the positional parameters +when an interactive shell is started. +

+ + +

+ + + + + + + + + + + +
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+

6.3.2 Is this Shell Interactive?

+ +

+ +To determine within a startup script whether or not Bash is +running interactively, +test the value of the `-' special parameter. +It contains i when the shell is interactive. For example: +

+ +
 
case "$-" in
+*i*)	echo This shell is interactive ;;
+*)	echo This shell is not interactive ;;
+esac
+

+ +Alternatively, startup scripts may examine the variable +PS1; it is unset in non-interactive shells, and set in +interactive shells. Thus: +

+ +
 
if [ -z "$PS1" ]; then
+        echo This shell is not interactive
+else
+        echo This shell is interactive
+fi
+

+ + +

+ + + + + + + + + + + +
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+

6.3.3 Interactive Shell Behavior

+ +

+ +When the shell is running interactively, it changes its behavior in +several ways. +

+ +

    +
  1. +Startup files are read and executed as described in 6.2 Bash Startup Files. +

    + +

  2. +Job Control (see section 7. Job Control) is enabled by default. When job +control is in effect, Bash ignores the keyboard-generated job control +signals SIGTTIN, SIGTTOU, and SIGTSTP. +

    + +

  3. +Bash expands and displays PS1 before reading the first line +of a command, and expands and displays PS2 before reading the +second and subsequent lines of a multi-line command. +

    + +

  4. +Bash executes the value of the PROMPT_COMMAND variable as a command +before printing the primary prompt, $PS1 +(see section 5.2 Bash Variables). +

    + +

  5. +Readline (see section 8. Command Line Editing) is used to read commands from +the user's terminal. +

    + +

  6. +Bash inspects the value of the ignoreeof option to set -o +instead of exiting immediately when it receives an EOF on its +standard input when reading a command (see section 4.3.1 The Set Builtin). +

    + +

  7. +Command history (see section 9.1 Bash History Facilities) +and history expansion (see section 9.3 History Expansion) +are enabled by default. +Bash will save the command history to the file named by $HISTFILE +when an interactive shell exits. +

    + +

  8. +Alias expansion (see section 6.6 Aliases) is performed by default. +

    + +

  9. +In the absence of any traps, Bash ignores SIGTERM +(see section 3.7.6 Signals). +

    + +

  10. +In the absence of any traps, SIGINT is caught and handled +((see section 3.7.6 Signals). +SIGINT will interrupt some shell builtins. +

    + +

  11. +An interactive login shell sends a SIGHUP to all jobs on exit +if the huponexit shell option has been enabled (see section 3.7.6 Signals). +

    + +

  12. +The `-n' invocation option is ignored, and `set -n' has +no effect (see section 4.3.1 The Set Builtin). +

    + +

  13. +Bash will check for mail periodically, depending on the values of the +MAIL, MAILPATH, and MAILCHECK shell variables +(see section 5.2 Bash Variables). +

    + +

  14. +Expansion errors due to references to unbound shell variables after +`set -u' has been enabled will not cause the shell to exit +(see section 4.3.1 The Set Builtin). +

    + +

  15. +The shell will not exit on expansion errors caused by var being unset +or null in ${var:?word} expansions +(see section 3.5.3 Shell Parameter Expansion). +

    + +

  16. +Redirection errors encountered by shell builtins will not cause the +shell to exit. +

    + +

  17. +When running in POSIX mode, a special builtin returning an error +status will not cause the shell to exit (see section 6.11 Bash POSIX Mode). +

    + +

  18. +A failed exec will not cause the shell to exit +(see section 4.1 Bourne Shell Builtins). +

    + +

  19. +Parser syntax errors will not cause the shell to exit. +

    + +

  20. +Simple spelling correction for directory arguments to the cd +builtin is enabled by default (see the description of the cdspell +option to the shopt builtin in 4.3.2 The Shopt Builtin). +

    + +

  21. +The shell will check the value of the TMOUT variable and exit +if a command is not read within the specified number of seconds after +printing $PS1 (see section 5.2 Bash Variables). +

    + +

+

+ + +

+ + + + + + + + + + + +
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+

6.4 Bash Conditional Expressions

+ +

+ +Conditional expressions are used by the [[ compound command +and the test and [ builtin commands. +

+ +Expressions may be unary or binary. +Unary expressions are often used to examine the status of a file. +There are string operators and numeric comparison operators as well. +If the file argument to one of the primaries is of the form +`/dev/fd/N', then file descriptor N is checked. +If the file argument to one of the primaries is one of +`/dev/stdin', `/dev/stdout', or `/dev/stderr', file +descriptor 0, 1, or 2, respectively, is checked. +

+ +Unless otherwise specified, primaries that operate on files follow symbolic +links and operate on the target of the link, rather than the link itself. +

+ +

+
-a file +
True if file exists. +

+ +

-b file +
True if file exists and is a block special file. +

+ +

-c file +
True if file exists and is a character special file. +

+ +

-d file +
True if file exists and is a directory. +

+ +

-e file +
True if file exists. +

+ +

-f file +
True if file exists and is a regular file. +

+ +

-g file +
True if file exists and its set-group-id bit is set. +

+ +

-h file +
True if file exists and is a symbolic link. +

+ +

-k file +
True if file exists and its "sticky" bit is set. +

+ +

-p file +
True if file exists and is a named pipe (FIFO). +

+ +

-r file +
True if file exists and is readable. +

+ +

-s file +
True if file exists and has a size greater than zero. +

+ +

-t fd +
True if file descriptor fd is open and refers to a terminal. +

+ +

-u file +
True if file exists and its set-user-id bit is set. +

+ +

-w file +
True if file exists and is writable. +

+ +

-x file +
True if file exists and is executable. +

+ +

-O file +
True if file exists and is owned by the effective user id. +

+ +

-G file +
True if file exists and is owned by the effective group id. +

+ +

-L file +
True if file exists and is a symbolic link. +

+ +

-S file +
True if file exists and is a socket. +

+ +

-N file +
True if file exists and has been modified since it was last read. +

+ +

file1 -nt file2 +
True if file1 is newer (according to modification date) +than file2, or if file1 exists and file2 does not. +

+ +

file1 -ot file2 +
True if file1 is older than file2, +or if file2 exists and file1 does not. +

+ +

file1 -ef file2 +
True if file1 and file2 refer to the same device and +inode numbers. +

+ +

-o optname +
True if shell option optname is enabled. +The list of options appears in the description of the `-o' +option to the set builtin (see section 4.3.1 The Set Builtin). +

+ +

-z string +
True if the length of string is zero. +

+ +

-n string +
string +
True if the length of string is non-zero. +

+ +

string1 == string2 +
True if the strings are equal. +`=' may be used in place of `==' for strict POSIX compliance. +

+ +

string1 != string2 +
True if the strings are not equal. +

+ +

string1 < string2 +
True if string1 sorts before string2 lexicographically +in the current locale. +

+ +

string1 > string2 +
True if string1 sorts after string2 lexicographically +in the current locale. +

+ +

arg1 OP arg2 +
OP is one of +`-eq', `-ne', `-lt', `-le', `-gt', or `-ge'. +These arithmetic binary operators return true if arg1 +is equal to, not equal to, less than, less than or equal to, +greater than, or greater than or equal to arg2, +respectively. Arg1 and arg2 +may be positive or negative integers. +

+ +

+

+ + +

+ + + + + + + + + + + +
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+

6.5 Shell Arithmetic

+ +

+ +The shell allows arithmetic expressions to be evaluated, as one of +the shell expansions or by the let and the `-i' option +to the declare builtins. +

+ +Evaluation is done in fixed-width integers with no check for overflow, +though division by 0 is trapped and flagged as an error. +The operators and their precedence, associativity, and values +are the same as in the C language. +The following list of operators is grouped into levels of +equal-precedence operators. +The levels are listed in order of decreasing precedence. +

+ +

+ +
id++ id-- +
variable post-increment and post-decrement +

+ +

++id --id +
variable pre-increment and pre-decrement +

+ +

- + +
unary minus and plus +

+ +

! ~ +
logical and bitwise negation +

+ +

** +
exponentiation +

+ +

* / % +
multiplication, division, remainder +

+ +

+ - +
addition, subtraction +

+ +

<< >> +
left and right bitwise shifts +

+ +

<= >= < > +
comparison +

+ +

== != +
equality and inequality +

+ +

& +
bitwise AND +

+ +

^ +
bitwise exclusive OR +

+ +

| +
bitwise OR +

+ +

&& +
logical AND +

+ +

|| +
logical OR +

+ +

expr ? expr : expr +
conditional operator +

+ +

= *= /= %= += -= <<= >>= &= ^= |= +
assignment +

+ +

expr1 , expr2 +
comma +
+

+ +Shell variables are allowed as operands; parameter expansion is +performed before the expression is evaluated. +Within an expression, shell variables may also be referenced by name +without using the parameter expansion syntax. +A shell variable that is null or unset evaluates to 0 when referenced +by name without using the parameter expansion syntax. +The value of a variable is evaluated as an arithmetic expression +when it is referenced, or when a variable which has been given the +integer attribute using `declare -i' is assigned a value. +A null value evaluates to 0. +A shell variable need not have its integer attribute turned on +to be used in an expression. +

+ +Constants with a leading 0 are interpreted as octal numbers. +A leading `0x' or `0X' denotes hexadecimal. Otherwise, +numbers take the form [base#]n, where base +is a decimal number between 2 and 64 representing the arithmetic +base, and n is a number in that base. If base# is +omitted, then base 10 is used. +The digits greater than 9 are represented by the lowercase letters, +the uppercase letters, `@', and `_', in that order. +If base is less than or equal to 36, lowercase and uppercase +letters may be used interchangeably to represent numbers between 10 +and 35. +

+ +Operators are evaluated in order of precedence. Sub-expressions in +parentheses are evaluated first and may override the precedence +rules above. +

+ + +

+ + + + + + + + + + + +
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+

6.6 Aliases

+ +

+ +Aliases allow a string to be substituted for a word when it is used +as the first word of a simple command. +The shell maintains a list of aliases that may be set and unset with +the alias and unalias builtin commands. +

+ +The first word of each simple command, if unquoted, is checked to see +if it has an alias. +If so, that word is replaced by the text of the alias. +The characters `/', `$', ``', `=' and any of the +shell metacharacters or quoting characters listed above may not appear +in an alias name. +The replacement text may contain any valid +shell input, including shell metacharacters. +The first word of the replacement text is tested for +aliases, but a word that is identical to an alias being expanded +is not expanded a second time. +This means that one may alias ls to "ls -F", +for instance, and Bash does not try to recursively expand the +replacement text. If the last character of the alias value is a +space or tab character, then the next command word following the +alias is also checked for alias expansion. +

+ +Aliases are created and listed with the alias +command, and removed with the unalias command. +

+ +There is no mechanism for using arguments in the replacement text, +as in csh. +If arguments are needed, a shell function should be used +(see section 3.3 Shell Functions). +

+ +Aliases are not expanded when the shell is not interactive, +unless the expand_aliases shell option is set using +shopt (see section 4.3.2 The Shopt Builtin). +

+ +The rules concerning the definition and use of aliases are +somewhat confusing. Bash +always reads at least one complete line +of input before executing any +of the commands on that line. Aliases are expanded when a +command is read, not when it is executed. Therefore, an +alias definition appearing on the same line as another +command does not take effect until the next line of input is read. +The commands following the alias definition +on that line are not affected by the new alias. +This behavior is also an issue when functions are executed. +Aliases are expanded when a function definition is read, +not when the function is executed, because a function definition +is itself a compound command. As a consequence, aliases +defined in a function are not available until after that +function is executed. To be safe, always put +alias definitions on a separate line, and do not use alias +in compound commands. +

+ +For almost every purpose, shell functions are preferred over aliases. +

+ + +

+ + + + + + + + + + + +
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+

6.7 Arrays

+ +

+ +Bash provides one-dimensional array variables. Any variable may be used as +an array; the declare builtin will explicitly declare an array. +There is no maximum +limit on the size of an array, nor any requirement that members +be indexed or assigned contiguously. Arrays are zero-based. +

+ +An array is created automatically if any variable is assigned to using +the syntax +
 
name[subscript]=value
+

+ +The subscript +is treated as an arithmetic expression that must evaluate to a number +greater than or equal to zero. To explicitly declare an array, use +
 
declare -a name
+
The syntax +
 
declare -a name[subscript]
+
is also accepted; the subscript is ignored. Attributes may be +specified for an array variable using the declare and +readonly builtins. Each attribute applies to all members of +an array. +

+ +Arrays are assigned to using compound assignments of the form +
 
name=(value1 ... valuen)
+
where each +value is of the form [[subscript]=]string. If +the optional subscript is supplied, that index is assigned to; +otherwise the index of the element assigned is the last index assigned +to by the statement plus one. Indexing starts at zero. +This syntax is also accepted by the declare +builtin. Individual array elements may be assigned to using the +name[subscript]=value syntax introduced above. +

+ +Any element of an array may be referenced using +${name[subscript]}. +The braces are required to avoid +conflicts with the shell's filename expansion operators. If the +subscript is `@' or `*', the word expands to all members +of the array name. These subscripts differ only when the word +appears within double quotes. +If the word is double-quoted, +${name[*]} expands to a single word with +the value of each array member separated by the first character of the +IFS variable, and ${name[@]} expands each element of +name to a separate word. When there are no array members, +${name[@]} expands to nothing. +If the double-quoted expansion occurs within a word, the expansion of +the first parameter is joined with the beginning part of the original +word, and the expansion of the last parameter is joined with the last +part of the original word. +This is analogous to the +expansion of the special parameters `@' and `*'. +${#name[subscript]} expands to the length of +${name[subscript]}. +If subscript is `@' or +`*', the expansion is the number of elements in the array. +Referencing an array variable without a subscript is equivalent to +referencing element zero. +

+ +The unset builtin is used to destroy arrays. +unset name[subscript] +destroys the array element at index subscript. +Care must be taken to avoid unwanted side effects caused by filename +generation. +unset name, where name is an array, removes the +entire array. A subscript of `*' or `@' also removes the +entire array. +

+ +The declare, local, and readonly +builtins each accept a `-a' +option to specify an array. The read +builtin accepts a `-a' +option to assign a list of words read from the standard input +to an array, and can read values from the standard input into +individual array elements. The set and declare +builtins display array values in a way that allows them to be +reused as input. +

+ + +

+ + + + + + + + + + + +
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+

6.8 The Directory Stack

+ +

+ +

+ +
6.8.1 Directory Stack Builtins  Bash builtin commands to manipulate + the directory stack.
+

+ +The directory stack is a list of recently-visited directories. The +pushd builtin adds directories to the stack as it changes +the current directory, and the popd builtin removes specified +directories from the stack and changes the current directory to +the directory removed. The dirs builtin displays the contents +of the directory stack. +

+ +The contents of the directory stack are also visible +as the value of the DIRSTACK shell variable. +

+ + +

+ + + + + + + + + + + +
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+

6.8.1 Directory Stack Builtins

+ +

+ +

+ +
dirs +
+
 
dirs [+N | -N] [-clpv]
+
Display the list of currently remembered directories. Directories +are added to the list with the pushd command; the +popd command removes directories from the list. +
+
+N +
Displays the Nth directory (counting from the left of the +list printed by dirs when invoked without options), starting +with zero. +
-N +
Displays the Nth directory (counting from the right of the +list printed by dirs when invoked without options), starting +with zero. +
-c +
Clears the directory stack by deleting all of the elements. +
-l +
Produces a longer listing; the default listing format uses a +tilde to denote the home directory. +
-p +
Causes dirs to print the directory stack with one entry per +line. +
-v +
Causes dirs to print the directory stack with one entry per +line, prefixing each entry with its index in the stack. +
+

+ +

popd +
+
 
popd [+N | -N] [-n]
+

+ +Remove the top entry from the directory stack, and cd +to the new top directory. +When no arguments are given, popd +removes the top directory from the stack and +performs a cd to the new top directory. The +elements are numbered from 0 starting at the first directory listed with +dirs; i.e., popd is equivalent to popd +0. +

+
+N +
Removes the Nth directory (counting from the left of the +list printed by dirs), starting with zero. +
-N +
Removes the Nth directory (counting from the right of the +list printed by dirs), starting with zero. +
-n +
Suppresses the normal change of directory when removing directories +from the stack, so that only the stack is manipulated. +
+

+ + +

pushd +
 
pushd [-n] [+N | -N | dir ]
+

+ +Save the current directory on the top of the directory stack +and then cd to dir. +With no arguments, pushd exchanges the top two directories. +

+ +

+
-n +
Suppresses the normal change of directory when adding directories +to the stack, so that only the stack is manipulated. +
+N +
Brings the Nth directory (counting from the left of the +list printed by dirs, starting with zero) to the top of +the list by rotating the stack. +
-N +
Brings the Nth directory (counting from the right of the +list printed by dirs, starting with zero) to the top of +the list by rotating the stack. +
dir +
Makes the current working directory be the top of the stack, and then +executes the equivalent of `cd dir'. +cds to dir. +
+

+ +

+

+ + +

+ + + + + + + + + + + +
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+

6.9 Controlling the Prompt

+ +

+ +The value of the variable PROMPT_COMMAND is examined just before +Bash prints each primary prompt. If PROMPT_COMMAND is set and +has a non-null value, then the +value is executed just as if it had been typed on the command line. +

+ +In addition, the following table describes the special characters which +can appear in the prompt variables: +

+ +

+
\a +
A bell character. +
\d +
The date, in "Weekday Month Date" format (e.g., "Tue May 26"). +
\D{format} +
The format is passed to strftime(3) and the result is inserted +into the prompt string; an empty format results in a locale-specific +time representation. The braces are required. +
\e +
An escape character. +
\h +
The hostname, up to the first `.'. +
\H +
The hostname. +
\j +
The number of jobs currently managed by the shell. +
\l +
The basename of the shell's terminal device name. +
\n +
A newline. +
\r +
A carriage return. +
\s +
The name of the shell, the basename of $0 (the portion +following the final slash). +
\t +
The time, in 24-hour HH:MM:SS format. +
\T +
The time, in 12-hour HH:MM:SS format. +
\@ +
The time, in 12-hour am/pm format. +
\A +
The time, in 24-hour HH:MM format. +
\u +
The username of the current user. +
\v +
The version of Bash (e.g., 2.00) +
\V +
The release of Bash, version + patchlevel (e.g., 2.00.0) +
\w +
The current working directory, with $HOME abbreviated with a tilde. +
\W +
The basename of $PWD, with $HOME abbreviated with a tilde. +
\! +
The history number of this command. +
\# +
The command number of this command. +
\$ +
If the effective uid is 0, #, otherwise $. +
\nnn +
The character whose ASCII code is the octal value nnn. +
\\ +
A backslash. +
\[ +
Begin a sequence of non-printing characters. This could be used to +embed a terminal control sequence into the prompt. +
\] +
End a sequence of non-printing characters. +
+

+ +The command number and the history number are usually different: +the history number of a command is its position in the history +list, which may include commands restored from the history file +(see section 9.1 Bash History Facilities), while the command number is +the position in the sequence of commands executed during the current +shell session. +

+ +After the string is decoded, it is expanded via +parameter expansion, command substitution, arithmetic +expansion, and quote removal, subject to the value of the +promptvars shell option (see section 4.2 Bash Builtin Commands). +

+ + +

+ + + + + + + + + + + +
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+

6.10 The Restricted Shell

+ +

+ +If Bash is started with the name rbash, or the +`--restricted' +or +`-r' +option is supplied at invocation, the shell becomes restricted. +A restricted shell is used to +set up an environment more controlled than the standard shell. +A restricted shell behaves identically to bash +with the exception that the following are disallowed or not performed: +

+ +

    +
  • +Changing directories with the cd builtin. +
  • +Setting or unsetting the values of the SHELL, PATH, +ENV, or BASH_ENV variables. +
  • +Specifying command names containing slashes. +
  • +Specifying a filename containing a slash as an argument to the . +builtin command. +
  • +Specifying a filename containing a slash as an argument to the `-p' +option to the hash builtin command. +
  • +Importing function definitions from the shell environment at startup. +
  • +Parsing the value of SHELLOPTS from the shell environment at startup. +
  • +Redirecting output using the `>', `>|', `<>', `>&', +`&>', and `>>' redirection operators. +
  • +Using the exec builtin to replace the shell with another command. +
  • +Adding or deleting builtin commands with the +`-f' and `-d' options to the enable builtin. +
  • +Using the enable builtin command to enable disabled shell builtins. +
  • +Specifying the `-p' option to the command builtin. +
  • +Turning off restricted mode with `set +r' or `set +o restricted'. +
+

+ +These restrictions are enforced after any startup files are read. +

+ +When a command that is found to be a shell script is executed +(see section 3.8 Shell Scripts), rbash turns off any restrictions in +the shell spawned to execute the script. +

+ + +

+ + + + + + + + + + + +
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+

6.11 Bash POSIX Mode

+ +

+ +Starting Bash with the `--posix' command-line option or executing +`set -o posix' while Bash is running will cause Bash to conform more +closely to the POSIX standard by changing the behavior to +match that specified by POSIX in areas where the Bash default differs. +

+ +When invoked as sh, Bash enters POSIX mode after reading the +startup files. +

+ +The following list is what's changed when `POSIX mode' is in effect: +

+ +

    +
  1. +When a command in the hash table no longer exists, Bash will re-search +$PATH to find the new location. This is also available with +`shopt -s checkhash'. +

    + +

  2. +The message printed by the job control code and builtins when a job +exits with a non-zero status is `Done(status)'. +

    + +

  3. +The message printed by the job control code and builtins when a job +is stopped is `Stopped(signame)', where signame is, for +example, SIGTSTP. +

    + +

  4. +The bg builtin uses the required format to describe each job placed +in the background, which does not include an indication of whether the job +is the current or previous job. +

    + +

  5. +Reserved words appearing in a context where reserved words are recognized +do not undergo alias expansion. +

    + +

  6. +The POSIX PS1 and PS2 expansions of `!' to +the history number and `!!' to `!' are enabled, +and parameter expansion is performed on the values of PS1 and +PS2 regardless of the setting of the promptvars option. +

    + +

  7. +The POSIX startup files are executed ($ENV) rather than +the normal Bash files. +

    + +

  8. +Tilde expansion is only performed on assignments preceding a command +name, rather than on all assignment statements on the line. +

    + +

  9. +The default history file is `~/.sh_history' (this is the +default value of $HISTFILE). +

    + +

  10. +The output of `kill -l' prints all the signal names on a single line, +separated by spaces, without the `SIG' prefix. +

    + +

  11. +The kill builtin does not accept signal names with a `SIG' +prefix. +

    + +

  12. +Non-interactive shells exit if filename in . filename +is not found. +

    + +

  13. +Non-interactive shells exit if a syntax error in an arithmetic expansion +results in an invalid expression. +

    + +

  14. +Redirection operators do not perform filename expansion on the word +in the redirection unless the shell is interactive. +

    + +

  15. +Redirection operators do not perform word splitting on the word in the +redirection. +

    + +

  16. +Function names must be valid shell names. That is, they may not +contain characters other than letters, digits, and underscores, and +may not start with a digit. Declaring a function with an invalid name +causes a fatal syntax error in non-interactive shells. +

    + +

  17. +POSIX special builtins are found before shell functions +during command lookup. +

    + +

  18. +If a POSIX special builtin returns an error status, a +non-interactive shell exits. The fatal errors are those listed in +the POSIX standard, and include things like passing incorrect options, +redirection errors, variable assignment errors for assignments preceding +the command name, and so on. +

    + +

  19. +If CDPATH is set, the cd builtin will not implicitly +append the current directory to it. This means that cd will +fail if no valid directory name can be constructed from +any of the entries in $CDPATH, even if the a directory with +the same name as the name given as an argument to cd exists +in the current directory. +

    + +

  20. +A non-interactive shell exits with an error status if a variable +assignment error occurs when no command name follows the assignment +statements. +A variable assignment error occurs, for example, when trying to assign +a value to a readonly variable. +

    + +

  21. +A non-interactive shell exits with an error status if the iteration +variable in a for statement or the selection variable in a +select statement is a readonly variable. +

    + +

  22. +Process substitution is not available. +

    + +

  23. +Assignment statements preceding POSIX special builtins +persist in the shell environment after the builtin completes. +

    + +

  24. +Assignment statements preceding shell function calls persist in the +shell environment after the function returns, as if a POSIX +special builtin command had been executed. +

    + +

  25. +The export and readonly builtin commands display their +output in the format required by POSIX. +

    + +

  26. +The trap builtin displays signal names without the leading +SIG. +

    + +

  27. +The trap builtin doesn't check the first argument for a possible +signal specification and revert the signal handling to the original +disposition if it is, unless that argument consists solely of digits and +is a valid signal number. If users want to reset the handler for a given +signal to the original disposition, they should use `-' as the +first argument. +

    + +

  28. +The . and source builtins do not search the current directory +for the filename argument if it is not found by searching PATH. +

    + +

  29. +Subshells spawned to execute command substitutions inherit the value of +the `-e' option from the parent shell. When not in POSIX mode, +Bash clears the `-e' option in such subshells. +

    + +

  30. +Alias expansion is always enabled, even in non-interactive shells. +

    + +

  31. +When the alias builtin displays alias definitions, it does not +display them with a leading `alias ' unless the `-p' option +is supplied. +

    + +

  32. +When the set builtin is invoked without options, it does not display +shell function names and definitions. +

    + +

  33. +When the set builtin is invoked without options, it displays +variable values without quotes, unless they contain shell metacharacters, +even if the result contains nonprinting characters. +

    + +

  34. +When the cd builtin is invoked in logical mode, and the pathname +constructed from $PWD and the directory name supplied as an argument +does not refer to an existing directory, cd will fail instead of +falling back to physical mode. +

    + +

  35. +When the pwd builtin is supplied the `-P' option, it resets +$PWD to a pathname containing no symlinks. +

    + +

  36. +The pwd builtin verifies that the value it prints is the same as the +current directory, even if it is not asked to check the file system with the +`-P' option. +

    + +

  37. +When listing the history, the fc builtin does not include an +indication of whether or not a history entry has been modified. +

    + +

  38. +The default editor used by fc is ed. +

    + +

  39. +The type and command builtins will not report a non-executable +file as having been found, though the shell will attempt to execute such a +file if it is the only so-named file found in $PATH. +

    + +

  40. +The vi editing mode will invoke the vi editor directly when +the `v' command is run, instead of checking $FCEDIT and +$EDITOR. +

    + +

  41. +When the xpg_echo option is enabled, Bash does not attempt to interpret +any arguments to echo as options. Each argument is displayed, after +escape characters are converted. +

    + +

+

+ +There is other POSIX behavior that Bash does not implement by +default even when in POSIX mode. +Specifically: +

+ +

    + +
  1. +The fc builtin checks $EDITOR as a program to edit history +entries if FCEDIT is unset, rather than defaulting directly to +ed. fc uses ed if EDITOR is unset. +

    + +

  2. +As noted above, Bash requires the xpg_echo option to be enabled for +the echo builtin to be fully conformant. +

    + +

+

+ +Bash can be configured to be POSIX-conformant by default, by specifying +the `--enable-strict-posix-default' to configure when building +(see section 10.8 Optional Features). +

+ + +

+ + + + + + + + + + + +
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+

7. Job Control

+ +

+ +This chapter discusses what job control is, how it works, and how +Bash allows you to access its facilities. +

+ +

+ + + +
7.1 Job Control Basics  How job control works.
7.2 Job Control Builtins  Bash builtin commands used to interact + with job control.
7.3 Job Control Variables  Variables Bash uses to customize job + control.
+

+ + +

+ + + + + + + + + + + +
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+

7.1 Job Control Basics

+ +

+ +Job control +refers to the ability to selectively stop (suspend) +the execution of processes and continue (resume) +their execution at a later point. A user typically employs +this facility via an interactive interface supplied jointly +by the system's terminal driver and Bash. +

+ +The shell associates a job with each pipeline. It keeps a +table of currently executing jobs, which may be listed with the +jobs command. When Bash starts a job +asynchronously, it prints a line that looks +like: +
 
[1] 25647
+
indicating that this job is job number 1 and that the process ID +of the last process in the pipeline associated with this job is +25647. All of the processes in a single pipeline are members of +the same job. Bash uses the job abstraction as the +basis for job control. +

+ +To facilitate the implementation of the user interface to job +control, the operating system maintains the notion of a current terminal +process group ID. Members of this process group (processes whose +process group ID is equal to the current terminal process group +ID) receive keyboard-generated signals such as SIGINT. +These processes are said to be in the foreground. Background +processes are those whose process group ID differs from the +terminal's; such processes are immune to keyboard-generated +signals. Only foreground processes are allowed to read from or +write to the terminal. Background processes which attempt to +read from (write to) the terminal are sent a SIGTTIN +(SIGTTOU) signal by the terminal driver, which, unless +caught, suspends the process. +

+ +If the operating system on which Bash is running supports +job control, Bash contains facilities to use it. Typing the +suspend character (typically `^Z', Control-Z) while a +process is running causes that process to be stopped and returns +control to Bash. Typing the delayed suspend character +(typically `^Y', Control-Y) causes the process to be stopped +when it attempts to read input from the terminal, and control to +be returned to Bash. The user then manipulates the state of +this job, using the bg command to continue it in the +background, the fg command to continue it in the +foreground, or the kill command to kill it. A `^Z' +takes effect immediately, and has the additional side effect of +causing pending output and typeahead to be discarded. +

+ +There are a number of ways to refer to a job in the shell. The +character `%' introduces a job name. +

+ +Job number n may be referred to as `%n'. +The symbols `%%' and `%+' refer to the shell's notion of the +current job, which is the last job stopped while it was in the foreground +or started in the background. +A single `%' (with no accompanying job specification) also refers +to the current job. +The previous job may be referenced using `%-'. In output +pertaining to jobs (e.g., the output of the jobs command), +the current job is always flagged with a `+', and the +previous job with a `-'. +

+ +A job may also be referred to +using a prefix of the name used to start it, or using a substring +that appears in its command line. For example, `%ce' refers +to a stopped ce job. Using `%?ce', on the +other hand, refers to any job containing the string `ce' in +its command line. If the prefix or substring matches more than one job, +Bash reports an error. +

+ +Simply naming a job can be used to bring it into the foreground: +`%1' is a synonym for `fg %1', bringing job 1 from the +background into the foreground. Similarly, `%1 &' resumes +job 1 in the background, equivalent to `bg %1' +

+ +The shell learns immediately whenever a job changes state. +Normally, Bash waits until it is about to print a prompt +before reporting changes in a job's status so as to not interrupt +any other output. +If the `-b' option to the set builtin is enabled, +Bash reports such changes immediately (see section 4.3.1 The Set Builtin). +Any trap on SIGCHLD is executed for each child process +that exits. +

+ +If an attempt to exit Bash is made while jobs are stopped, (or running, if +the checkjobs option is enabled -- see 4.3.2 The Shopt Builtin), the +shell prints a warning message, and if the checkjobs option is +enabled, lists the jobs and their statuses. +The jobs command may then be used to inspect their status. +If a second attempt to exit is made without an intervening command, +Bash does not print another warning, and any stopped jobs are terminated. +

+ + +

+ + + + + + + + + + + +
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+

7.2 Job Control Builtins

+ +

+ +

+ +
bg +
+
 
bg [jobspec ...]
+
Resume each suspended job jobspec in the background, as if it +had been started with `&'. +If jobspec is not supplied, the current job is used. +The return status is zero unless it is run when job control is not +enabled, or, when run with job control enabled, any +jobspec was not found or specifies a job +that was started without job control. +

+ +

fg +
+
 
fg [jobspec]
+
Resume the job jobspec in the foreground and make it the current job. +If jobspec is not supplied, the current job is used. +The return status is that of the command placed into the foreground, +or non-zero if run when job control is disabled or, when run with +job control enabled, jobspec does not specify a valid job or +jobspec specifies a job that was started without job control. +

+ +

jobs +
+
 
jobs [-lnprs] [jobspec]
+jobs -x command [arguments]
+

+ +The first form lists the active jobs. The options have the +following meanings: +

+ +

+
-l +
List process IDs in addition to the normal information. +

+ +

-n +
Display information only about jobs that have changed status since +the user was last notified of their status. +

+ +

-p +
List only the process ID of the job's process group leader. +

+ +

-r +
Restrict output to running jobs. +

+ +

-s +
Restrict output to stopped jobs. +
+

+ +If jobspec is given, +output is restricted to information about that job. +If jobspec is not supplied, the status of all jobs is +listed. +

+ +If the `-x' option is supplied, jobs replaces any +jobspec found in command or arguments with the +corresponding process group ID, and executes command, +passing it arguments, returning its exit status. +

+ +

kill +
+
 
kill [-s sigspec] [-n signum] [-sigspec] jobspec or pid
+kill -l [exit_status]
+
Send a signal specified by sigspec or signum to the process +named by job specification jobspec or process ID pid. +sigspec is either a case-insensitive signal name such as +SIGINT (with or without the SIG prefix) +or a signal number; signum is a signal number. +If sigspec and signum are not present, SIGTERM is used. +The `-l' option lists the signal names. +If any arguments are supplied when `-l' is given, the names of the +signals corresponding to the arguments are listed, and the return status +is zero. +exit_status is a number specifying a signal number or the exit +status of a process terminated by a signal. +The return status is zero if at least one signal was successfully sent, +or non-zero if an error occurs or an invalid option is encountered. +

+ +

wait +
+
 
wait [jobspec or pid ...]
+
Wait until the child process specified by each process ID pid +or job specification jobspec exits and return the exit status of the +last command waited for. +If a job spec is given, all processes in the job are waited for. +If no arguments are given, all currently active child processes are +waited for, and the return status is zero. +If neither jobspec nor pid specifies an active child process +of the shell, the return status is 127. +

+ +

disown +
+
 
disown [-ar] [-h] [jobspec ...]
+
Without options, each jobspec is removed from the table of +active jobs. +If the `-h' option is given, the job is not removed from the table, +but is marked so that SIGHUP is not sent to the job if the shell +receives a SIGHUP. +If jobspec is not present, and neither the `-a' nor `-r' +option is supplied, the current job is used. +If no jobspec is supplied, the `-a' option means to remove or +mark all jobs; the `-r' option without a jobspec +argument restricts operation to running jobs. +

+ +

suspend +
+
 
suspend [-f]
+
Suspend the execution of this shell until it receives a +SIGCONT signal. The `-f' option means to suspend +even if the shell is a login shell. +

+ +

+

+ +When job control is not active, the kill and wait +builtins do not accept jobspec arguments. They must be +supplied process IDs. +

+ + +

+ + + + + + + + + + + +
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+

7.3 Job Control Variables

+ +

+ +

+ + +
auto_resume +
+This variable controls how the shell interacts with the user and +job control. If this variable exists then single word simple +commands without redirections are treated as candidates for resumption +of an existing job. There is no ambiguity allowed; if there is +more than one job beginning with the string typed, then +the most recently accessed job will be selected. +The name of a stopped job, in this context, is the command line +used to start it. If this variable is set to the value `exact', +the string supplied must match the name of a stopped job exactly; +if set to `substring', +the string supplied needs to match a substring of the name of a +stopped job. The `substring' value provides functionality +analogous to the `%?' job ID (see section 7.1 Job Control Basics). +If set to any other value, the supplied string must +be a prefix of a stopped job's name; this provides functionality +analogous to the `%' job ID. +

+ +

+

+ + +

+ + +

+ + + + + + + + + + + +
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+

8. Command Line Editing

+ +

+ +This chapter describes the basic features of the GNU +command line editing interface. +Command line editing is provided by the Readline library, which is +used by several different programs, including Bash. +

+ +

+ + + + + + + +
8.1 Introduction to Line Editing  Notation used in this text.
8.2 Readline Interaction  The minimum set of commands for editing a line.
8.3 Readline Init File  Customizing Readline from a user's view.
8.4 Bindable Readline Commands  A description of most of the Readline commands + available for binding
8.5 Readline vi Mode  A short description of how to make Readline + behave like the vi editor.
8.6 Programmable Completion  How to specify the possible completions for + a specific command.
8.7 Programmable Completion Builtins  Builtin commands to specify how to + complete arguments for a particular command.
+

+ + +

+ + + + + + + + + + + +
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+

8.1 Introduction to Line Editing

+ +

+ +The following paragraphs describe the notation used to represent +keystrokes. +

+ +The text C-k is read as `Control-K' and describes the character +produced when the k key is pressed while the Control key +is depressed. +

+ +The text M-k is read as `Meta-K' and describes the character +produced when the Meta key (if you have one) is depressed, and the k +key is pressed. +The Meta key is labeled ALT on many keyboards. +On keyboards with two keys labeled ALT (usually to either side of +the space bar), the ALT on the left side is generally set to +work as a Meta key. +The ALT key on the right may also be configured to work as a +Meta key or may be configured as some other modifier, such as a +Compose key for typing accented characters. +

+ +If you do not have a Meta or ALT key, or another key working as +a Meta key, the identical keystroke can be generated by typing ESC +first, and then typing k. +Either process is known as metafying the k key. +

+ +The text M-C-k is read as `Meta-Control-k' and describes the +character produced by metafying C-k. +

+ +In addition, several keys have their own names. Specifically, +DEL, ESC, LFD, SPC, RET, and TAB all +stand for themselves when seen in this text, or in an init file +(see section 8.3 Readline Init File). +If your keyboard lacks a LFD key, typing C-j will +produce the desired character. +The RET key may be labeled Return or Enter on +some keyboards. +

+ + +

+ + + + + + + + + + + +
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+

8.2 Readline Interaction

+ +

+ +Often during an interactive session you type in a long line of text, +only to notice that the first word on the line is misspelled. The +Readline library gives you a set of commands for manipulating the text +as you type it in, allowing you to just fix your typo, and not forcing +you to retype the majority of the line. Using these editing commands, +you move the cursor to the place that needs correction, and delete or +insert the text of the corrections. Then, when you are satisfied with +the line, you simply press RET. You do not have to be at the +end of the line to press RET; the entire line is accepted +regardless of the location of the cursor within the line. +

+ +

+ + + + + +
8.2.1 Readline Bare Essentials  The least you need to know about Readline.
8.2.2 Readline Movement Commands  Moving about the input line.
8.2.3 Readline Killing Commands  How to delete text, and how to get it back!
8.2.4 Readline Arguments  Giving numeric arguments to commands.
8.2.5 Searching for Commands in the History  Searching through previous lines.
+

+ + +

+ + + + + + + + + + + +
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+

8.2.1 Readline Bare Essentials

+ +

+ +In order to enter characters into the line, simply type them. The typed +character appears where the cursor was, and then the cursor moves one +space to the right. If you mistype a character, you can use your +erase character to back up and delete the mistyped character. +

+ +Sometimes you may mistype a character, and +not notice the error until you have typed several other characters. In +that case, you can type C-b to move the cursor to the left, and then +correct your mistake. Afterwards, you can move the cursor to the right +with C-f. +

+ +When you add text in the middle of a line, you will notice that characters +to the right of the cursor are `pushed over' to make room for the text +that you have inserted. Likewise, when you delete text behind the cursor, +characters to the right of the cursor are `pulled back' to fill in the +blank space created by the removal of the text. A list of the bare +essentials for editing the text of an input line follows. +

+ +

+
C-b +
Move back one character. +
C-f +
Move forward one character. +
DEL or Backspace +
Delete the character to the left of the cursor. +
C-d +
Delete the character underneath the cursor. +
Printing characters +
Insert the character into the line at the cursor. +
C-_ or C-x C-u +
Undo the last editing command. You can undo all the way back to an +empty line. +
+

+ +(Depending on your configuration, the Backspace key be set to +delete the character to the left of the cursor and the DEL key set +to delete the character underneath the cursor, like C-d, rather +than the character to the left of the cursor.) +

+ + +

+ + + + + + + + + + + +
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+

8.2.2 Readline Movement Commands

+ +

+ +The above table describes the most basic keystrokes that you need +in order to do editing of the input line. For your convenience, many +other commands have been added in addition to C-b, C-f, +C-d, and DEL. Here are some commands for moving more rapidly +about the line. +

+ +

+
C-a +
Move to the start of the line. +
C-e +
Move to the end of the line. +
M-f +
Move forward a word, where a word is composed of letters and digits. +
M-b +
Move backward a word. +
C-l +
Clear the screen, reprinting the current line at the top. +
+

+ +Notice how C-f moves forward a character, while M-f moves +forward a word. It is a loose convention that control keystrokes +operate on characters while meta keystrokes operate on words. +

+ + +

+ + + + + + + + + + + +
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+

8.2.3 Readline Killing Commands

+ +

+ + + +

+ +Killing text means to delete the text from the line, but to save +it away for later use, usually by yanking (re-inserting) +it back into the line. +(`Cut' and `paste' are more recent jargon for `kill' and `yank'.) +

+ +If the description for a command says that it `kills' text, then you can +be sure that you can get the text back in a different (or the same) +place later. +

+ +When you use a kill command, the text is saved in a kill-ring. +Any number of consecutive kills save all of the killed text together, so +that when you yank it back, you get it all. The kill +ring is not line specific; the text that you killed on a previously +typed line is available to be yanked back later, when you are typing +another line. + +

+ +Here is the list of commands for killing text. +

+ +

+
C-k +
Kill the text from the current cursor position to the end of the line. +

+ +

M-d +
Kill from the cursor to the end of the current word, or, if between +words, to the end of the next word. +Word boundaries are the same as those used by M-f. +

+ +

M-DEL +
Kill from the cursor the start of the current word, or, if between +words, to the start of the previous word. +Word boundaries are the same as those used by M-b. +

+ +

C-w +
Kill from the cursor to the previous whitespace. This is different than +M-DEL because the word boundaries differ. +

+ +

+

+ +Here is how to yank the text back into the line. Yanking +means to copy the most-recently-killed text from the kill buffer. +

+ +

+
C-y +
Yank the most recently killed text back into the buffer at the cursor. +

+ +

M-y +
Rotate the kill-ring, and yank the new top. You can only do this if +the prior command is C-y or M-y. +
+

+ + +

+ + + + + + + + + + + +
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+

8.2.4 Readline Arguments

+ +

+ +You can pass numeric arguments to Readline commands. Sometimes the +argument acts as a repeat count, other times it is the sign of the +argument that is significant. If you pass a negative argument to a +command which normally acts in a forward direction, that command will +act in a backward direction. For example, to kill text back to the +start of the line, you might type `M-- C-k'. +

+ +The general way to pass numeric arguments to a command is to type meta +digits before the command. If the first `digit' typed is a minus +sign (`-'), then the sign of the argument will be negative. Once +you have typed one meta digit to get the argument started, you can type +the remainder of the digits, and then the command. For example, to give +the C-d command an argument of 10, you could type `M-1 0 C-d', +which will delete the next ten characters on the input line. +

+ + +

+ + + + + + + + + + + +
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+

8.2.5 Searching for Commands in the History

+ +

+ +Readline provides commands for searching through the command history +(see section 9.1 Bash History Facilities) +for lines containing a specified string. +There are two search modes: incremental and non-incremental. +

+ +Incremental searches begin before the user has finished typing the +search string. +As each character of the search string is typed, Readline displays +the next entry from the history matching the string typed so far. +An incremental search requires only as many characters as needed to +find the desired history entry. +To search backward in the history for a particular string, type +C-r. Typing C-s searches forward through the history. +The characters present in the value of the isearch-terminators variable +are used to terminate an incremental search. +If that variable has not been assigned a value, the ESC and +C-J characters will terminate an incremental search. +C-g will abort an incremental search and restore the original line. +When the search is terminated, the history entry containing the +search string becomes the current line. +

+ +To find other matching entries in the history list, type C-r or +C-s as appropriate. +This will search backward or forward in the history for the next +entry matching the search string typed so far. +Any other key sequence bound to a Readline command will terminate +the search and execute that command. +For instance, a RET will terminate the search and accept +the line, thereby executing the command from the history list. +A movement command will terminate the search, make the last line found +the current line, and begin editing. +

+ +Readline remembers the last incremental search string. If two +C-rs are typed without any intervening characters defining a new +search string, any remembered search string is used. +

+ +Non-incremental searches read the entire search string before starting +to search for matching history lines. The search string may be +typed by the user or be part of the contents of the current line. +

+ + +

+ + + + + + + + + + + +
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+

8.3 Readline Init File

+ +

+ +Although the Readline library comes with a set of Emacs-like +keybindings installed by default, it is possible to use a different set +of keybindings. +Any user can customize programs that use Readline by putting +commands in an inputrc file, conventionally in his home directory. +The name of this +file is taken from the value of the shell variable INPUTRC. If +that variable is unset, the default is `~/.inputrc'. If that +file does not exist or cannot be read, the ultimate default is +`/etc/inputrc'. +

+ +When a program which uses the Readline library starts up, the +init file is read, and the key bindings are set. +

+ +In addition, the C-x C-r command re-reads this init file, thus +incorporating any changes that you might have made to it. +

+ +

+ +
8.3.1 Readline Init File Syntax  Syntax for the commands in the inputrc file.
+ +
+ + +
8.3.2 Conditional Init Constructs  Conditional key bindings in the inputrc file.
+ +
+ + +
8.3.3 Sample Init File  An example inputrc file.
+

+ + +

+ + + + + + + + + + + +
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+

8.3.1 Readline Init File Syntax

+ +

+ +There are only a few basic constructs allowed in the +Readline init file. Blank lines are ignored. +Lines beginning with a `#' are comments. +Lines beginning with a `$' indicate conditional +constructs (see section 8.3.2 Conditional Init Constructs). Other lines +denote variable settings and key bindings. +

+ +

+
Variable Settings +
You can modify the run-time behavior of Readline by +altering the values of variables in Readline +using the set command within the init file. +The syntax is simple: +

+ +
 
set variable value
+

+ +Here, for example, is how to +change from the default Emacs-like key binding to use +vi line editing commands: +

+ +
 
set editing-mode vi
+

+ +Variable names and values, where appropriate, are recognized without regard +to case. Unrecognized variable names are ignored. +

+ +Boolean variables (those that can be set to on or off) are set to on if +the value is null or empty, on (case-insensitive), or 1. Any other +value results in the variable being set to off. +

+ +The bind -V command lists the current Readline variable names +and values. See section 4.2 Bash Builtin Commands. +

+ +A great deal of run-time behavior is changeable with the following +variables. +

+ + +

+ +
bell-style +
+Controls what happens when Readline wants to ring the terminal bell. +If set to `none', Readline never rings the bell. If set to +`visible', Readline uses a visible bell if one is available. +If set to `audible' (the default), Readline attempts to ring +the terminal's bell. +

+ +

bind-tty-special-chars +
+If set to `on', Readline attempts to bind the control characters +treated specially by the kernel's terminal driver to their Readline +equivalents. +

+ +

comment-begin +
+The string to insert at the beginning of the line when the +insert-comment command is executed. The default value +is "#". +

+ +

completion-ignore-case +
If set to `on', Readline performs filename matching and completion +in a case-insensitive fashion. +The default value is `off'. +

+ +

completion-query-items +
+The number of possible completions that determines when the user is +asked whether the list of possibilities should be displayed. +If the number of possible completions is greater than this value, +Readline will ask the user whether or not he wishes to view +them; otherwise, they are simply listed. +This variable must be set to an integer value greater than or equal to 0. +A negative value means Readline should never ask. +The default limit is 100. +

+ +

convert-meta +
+If set to `on', Readline will convert characters with the +eighth bit set to an ASCII key sequence by stripping the eighth +bit and prefixing an ESC character, converting them to a +meta-prefixed key sequence. The default value is `on'. +

+ +

disable-completion +
+If set to `On', Readline will inhibit word completion. +Completion characters will be inserted into the line as if they had +been mapped to self-insert. The default is `off'. +

+ +

editing-mode +
+The editing-mode variable controls which default set of +key bindings is used. By default, Readline starts up in Emacs editing +mode, where the keystrokes are most similar to Emacs. This variable can be +set to either `emacs' or `vi'. +

+ +

enable-keypad +
+When set to `on', Readline will try to enable the application +keypad when it is called. Some systems need this to enable the +arrow keys. The default is `off'. +

+ +

expand-tilde +
+If set to `on', tilde expansion is performed when Readline +attempts word completion. The default is `off'. +

+ +

history-preserve-point +
+If set to `on', the history code attempts to place point at the +same location on each history line retrieved with previous-history +or next-history. The default is `off'. +

+ +

horizontal-scroll-mode +
+This variable can be set to either `on' or `off'. Setting it +to `on' means that the text of the lines being edited will scroll +horizontally on a single screen line when they are longer than the width +of the screen, instead of wrapping onto a new screen line. By default, +this variable is set to `off'. +

+ +

input-meta +
+ +If set to `on', Readline will enable eight-bit input (it +will not clear the eighth bit in the characters it reads), +regardless of what the terminal claims it can support. The +default value is `off'. The name meta-flag is a +synonym for this variable. +

+ +

isearch-terminators +
+The string of characters that should terminate an incremental search without +subsequently executing the character as a command (see section 8.2.5 Searching for Commands in the History). +If this variable has not been given a value, the characters ESC and +C-J will terminate an incremental search. +

+ +

keymap +
+Sets Readline's idea of the current keymap for key binding commands. +Acceptable keymap names are +emacs, +emacs-standard, +emacs-meta, +emacs-ctlx, +vi, +vi-move, +vi-command, and +vi-insert. +vi is equivalent to vi-command; emacs is +equivalent to emacs-standard. The default value is emacs. +The value of the editing-mode variable also affects the +default keymap. +

+ +

mark-directories +
If set to `on', completed directory names have a slash +appended. The default is `on'. +

+ +

mark-modified-lines +
+This variable, when set to `on', causes Readline to display an +asterisk (`*') at the start of history lines which have been modified. +This variable is `off' by default. +

+ +

mark-symlinked-directories +
+If set to `on', completed names which are symbolic links +to directories have a slash appended (subject to the value of +mark-directories). +The default is `off'. +

+ +

match-hidden-files +
+This variable, when set to `on', causes Readline to match files whose +names begin with a `.' (hidden files) when performing filename +completion, unless the leading `.' is +supplied by the user in the filename to be completed. +This variable is `on' by default. +

+ +

output-meta +
+If set to `on', Readline will display characters with the +eighth bit set directly rather than as a meta-prefixed escape +sequence. The default is `off'. +

+ +

page-completions +
+If set to `on', Readline uses an internal more-like pager +to display a screenful of possible completions at a time. +This variable is `on' by default. +

+ +

print-completions-horizontally +
If set to `on', Readline will display completions with matches +sorted horizontally in alphabetical order, rather than down the screen. +The default is `off'. +

+ +

show-all-if-ambiguous +
+This alters the default behavior of the completion functions. If +set to `on', +words which have more than one possible completion cause the +matches to be listed immediately instead of ringing the bell. +The default value is `off'. +

+ +

show-all-if-unmodified +
+This alters the default behavior of the completion functions in +a fashion similar to show-all-if-ambiguous. +If set to `on', +words which have more than one possible completion without any +possible partial completion (the possible completions don't share +a common prefix) cause the matches to be listed immediately instead +of ringing the bell. +The default value is `off'. +

+ +

visible-stats +
+If set to `on', a character denoting a file's type +is appended to the filename when listing possible +completions. The default is `off'. +

+ +

+

+ +

Key Bindings +
The syntax for controlling key bindings in the init file is +simple. First you need to find the name of the command that you +want to change. The following sections contain tables of the command +name, the default keybinding, if any, and a short description of what +the command does. +

+ +Once you know the name of the command, simply place on a line +in the init file the name of the key +you wish to bind the command to, a colon, and then the name of the +command. +There can be no space between the key name and the colon -- that will be +interpreted as part of the key name. +The name of the key can be expressed in different ways, depending on +what you find most comfortable. +

+ +In addition to command names, readline allows keys to be bound +to a string that is inserted when the key is pressed (a macro). +

+ +The bind -p command displays Readline function names and +bindings in a format that can put directly into an initialization file. +See section 4.2 Bash Builtin Commands. +

+ +

+
keyname: function-name or macro +
keyname is the name of a key spelled out in English. For example: +
 
Control-u: universal-argument
+Meta-Rubout: backward-kill-word
+Control-o: "> output"
+

+ +In the above example, C-u is bound to the function +universal-argument, +M-DEL is bound to the function backward-kill-word, and +C-o is bound to run the macro +expressed on the right hand side (that is, to insert the text +`> output' into the line). +

+ +A number of symbolic character names are recognized while +processing this key binding syntax: +DEL, +ESC, +ESCAPE, +LFD, +NEWLINE, +RET, +RETURN, +RUBOUT, +SPACE, +SPC, +and +TAB. +

+ +

"keyseq": function-name or macro +
keyseq differs from keyname above in that strings +denoting an entire key sequence can be specified, by placing +the key sequence in double quotes. Some GNU Emacs style key +escapes can be used, as in the following example, but the +special character names are not recognized. +

+ +
 
"\C-u": universal-argument
+"\C-x\C-r": re-read-init-file
+"\e[11~": "Function Key 1"
+

+ +In the above example, C-u is again bound to the function +universal-argument (just as it was in the first example), +`C-x C-r' is bound to the function re-read-init-file, +and `ESC [ 1 1 ~' is bound to insert +the text `Function Key 1'. +

+ +

+

+ +The following GNU Emacs style escape sequences are available when +specifying key sequences: +

+ +

+
\C- +
control prefix +
\M- +
meta prefix +
\e +
an escape character +
\\ +
backslash +
\" +
", a double quotation mark +
\' +
', a single quote or apostrophe +
+

+ +In addition to the GNU Emacs style escape sequences, a second +set of backslash escapes is available: +

+ +

+
\a +
alert (bell) +
\b +
backspace +
\d +
delete +
\f +
form feed +
\n +
newline +
\r +
carriage return +
\t +
horizontal tab +
\v +
vertical tab +
\nnn +
the eight-bit character whose value is the octal value nnn +(one to three digits) +
\xHH +
the eight-bit character whose value is the hexadecimal value HH +(one or two hex digits) +
+

+ +When entering the text of a macro, single or double quotes must +be used to indicate a macro definition. +Unquoted text is assumed to be a function name. +In the macro body, the backslash escapes described above are expanded. +Backslash will quote any other character in the macro text, +including `"' and `''. +For example, the following binding will make `C-x \' +insert a single `\' into the line: +
 
"\C-x\\": "\\"
+

+ +

+

+ + +

+ + + + + + + + + + + +
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+

8.3.2 Conditional Init Constructs

+ +

+ +Readline implements a facility similar in spirit to the conditional +compilation features of the C preprocessor which allows key +bindings and variable settings to be performed as the result +of tests. There are four parser directives used. +

+ +

+
$if +
The $if construct allows bindings to be made based on the +editing mode, the terminal being used, or the application using +Readline. The text of the test extends to the end of the line; +no characters are required to isolate it. +

+ +

+
mode +
The mode= form of the $if directive is used to test +whether Readline is in emacs or vi mode. +This may be used in conjunction +with the `set keymap' command, for instance, to set bindings in +the emacs-standard and emacs-ctlx keymaps only if +Readline is starting out in emacs mode. +

+ +

term +
The term= form may be used to include terminal-specific +key bindings, perhaps to bind the key sequences output by the +terminal's function keys. The word on the right side of the +`=' is tested against both the full name of the terminal and +the portion of the terminal name before the first `-'. This +allows sun to match both sun and sun-cmd, +for instance. +

+ +

application +
The application construct is used to include +application-specific settings. Each program using the Readline +library sets the application name, and you can test for +a particular value. +This could be used to bind key sequences to functions useful for +a specific program. For instance, the following command adds a +key sequence that quotes the current or previous word in Bash: +
 
$if Bash
+# Quote the current or previous word
+"\C-xq": "\eb\"\ef\""
+$endif
+
+

+ +

$endif +
This command, as seen in the previous example, terminates an +$if command. +

+ +

$else +
Commands in this branch of the $if directive are executed if +the test fails. +

+ +

$include +
This directive takes a single filename as an argument and reads commands +and bindings from that file. +For example, the following directive reads from `/etc/inputrc': +
 
$include /etc/inputrc
+
+

+ + +

+ + + + + + + + + + + +
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+

8.3.3 Sample Init File

+ +

+ +Here is an example of an inputrc file. This illustrates key +binding, variable assignment, and conditional syntax. +

+ +
 
# This file controls the behaviour of line input editing for
+# programs that use the GNU Readline library.  Existing
+# programs include FTP, Bash, and GDB.
+#
+# You can re-read the inputrc file with C-x C-r.
+# Lines beginning with '#' are comments.
+#
+# First, include any systemwide bindings and variable
+# assignments from /etc/Inputrc
+$include /etc/Inputrc
+
+#
+# Set various bindings for emacs mode.
+
+set editing-mode emacs 
+
+$if mode=emacs
+
+Meta-Control-h:	backward-kill-word	Text after the function name is ignored
+
+#
+# Arrow keys in keypad mode
+#
+#"\M-OD":        backward-char
+#"\M-OC":        forward-char
+#"\M-OA":        previous-history
+#"\M-OB":        next-history
+#
+# Arrow keys in ANSI mode
+#
+"\M-[D":        backward-char
+"\M-[C":        forward-char
+"\M-[A":        previous-history
+"\M-[B":        next-history
+#
+# Arrow keys in 8 bit keypad mode
+#
+#"\M-\C-OD":       backward-char
+#"\M-\C-OC":       forward-char
+#"\M-\C-OA":       previous-history
+#"\M-\C-OB":       next-history
+#
+# Arrow keys in 8 bit ANSI mode
+#
+#"\M-\C-[D":       backward-char
+#"\M-\C-[C":       forward-char
+#"\M-\C-[A":       previous-history
+#"\M-\C-[B":       next-history
+
+C-q: quoted-insert
+
+$endif
+
+# An old-style binding.  This happens to be the default.
+TAB: complete
+
+# Macros that are convenient for shell interaction
+$if Bash
+# edit the path
+"\C-xp": "PATH=${PATH}\e\C-e\C-a\ef\C-f"
+# prepare to type a quoted word --
+# insert open and close double quotes
+# and move to just after the open quote
+"\C-x\"": "\"\"\C-b"
+# insert a backslash (testing backslash escapes
+# in sequences and macros)
+"\C-x\\": "\\"
+# Quote the current or previous word
+"\C-xq": "\eb\"\ef\""
+# Add a binding to refresh the line, which is unbound
+"\C-xr": redraw-current-line
+# Edit variable on current line.
+"\M-\C-v": "\C-a\C-k$\C-y\M-\C-e\C-a\C-y="
+$endif
+
+# use a visible bell if one is available
+set bell-style visible
+
+# don't strip characters to 7 bits when reading
+set input-meta on
+
+# allow iso-latin1 characters to be inserted rather
+# than converted to prefix-meta sequences
+set convert-meta off
+
+# display characters with the eighth bit set directly
+# rather than as meta-prefixed characters
+set output-meta on
+
+# if there are more than 150 possible completions for
+# a word, ask the user if he wants to see all of them
+set completion-query-items 150
+
+# For FTP
+$if Ftp
+"\C-xg": "get \M-?"
+"\C-xt": "put \M-?"
+"\M-.": yank-last-arg
+$endif
+

+ + +

+ + + + + + + + + + + +
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+

8.4 Bindable Readline Commands

+ +

+ +

+ + + + + + + + +
8.4.1 Commands For Moving  Moving about the line.
8.4.2 Commands For Manipulating The History  Getting at previous lines.
8.4.3 Commands For Changing Text  Commands for changing text.
8.4.4 Killing And Yanking  Commands for killing and yanking.
8.4.5 Specifying Numeric Arguments  Specifying numeric arguments, repeat counts.
8.4.6 Letting Readline Type For You  Getting Readline to do the typing for you.
8.4.7 Keyboard Macros  Saving and re-executing typed characters
8.4.8 Some Miscellaneous Commands  Other miscellaneous commands.
+

+ +This section describes Readline commands that may be bound to key +sequences. +You can list your key bindings by executing +bind -P or, for a more terse format, suitable for an +inputrc file, bind -p. (See section 4.2 Bash Builtin Commands.) +Command names without an accompanying key sequence are unbound by default. +

+ +In the following descriptions, point refers to the current cursor +position, and mark refers to a cursor position saved by the +set-mark command. +The text between the point and mark is referred to as the region. +

+ + +

+ + + + + + + + + + + +
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+

8.4.1 Commands For Moving

+ +
+ +
beginning-of-line (C-a) +
+Move to the start of the current line. +

+ + +

end-of-line (C-e) +
+Move to the end of the line. +

+ + +

forward-char (C-f) +
+Move forward a character. +

+ + +

backward-char (C-b) +
+Move back a character. +

+ + +

forward-word (M-f) +
+Move forward to the end of the next word. Words are composed of +letters and digits. +

+ + +

backward-word (M-b) +
+Move back to the start of the current or previous word. Words are +composed of letters and digits. +

+ + +

clear-screen (C-l) +
+Clear the screen and redraw the current line, +leaving the current line at the top of the screen. +

+ + +

redraw-current-line () +
+Refresh the current line. By default, this is unbound. +

+ +

+

+ + +

+ + + + + + + + + + + +
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+

8.4.2 Commands For Manipulating The History

+ +

+ +

+ +
accept-line (Newline or Return) +
+Accept the line regardless of where the cursor is. +If this line is +non-empty, add it to the history list according to the setting of +the HISTCONTROL and HISTIGNORE variables. +If this line is a modified history line, then restore the history line +to its original state. +

+ + +

previous-history (C-p) +
+Move `back' through the history list, fetching the previous command. +

+ + +

next-history (C-n) +
+Move `forward' through the history list, fetching the next command. +

+ + +

beginning-of-history (M-<) +
+Move to the first line in the history. +

+ + +

end-of-history (M->) +
+Move to the end of the input history, i.e., the line currently +being entered. +

+ + +

reverse-search-history (C-r) +
+Search backward starting at the current line and moving `up' through +the history as necessary. This is an incremental search. +

+ + +

forward-search-history (C-s) +
+Search forward starting at the current line and moving `down' through +the the history as necessary. This is an incremental search. +

+ + +

non-incremental-reverse-search-history (M-p) +
+Search backward starting at the current line and moving `up' +through the history as necessary using a non-incremental search +for a string supplied by the user. +

+ + +

non-incremental-forward-search-history (M-n) +
+Search forward starting at the current line and moving `down' +through the the history as necessary using a non-incremental search +for a string supplied by the user. +

+ + +

history-search-forward () +
+Search forward through the history for the string of characters +between the start of the current line and the point. +This is a non-incremental search. +By default, this command is unbound. +

+ + +

history-search-backward () +
+Search backward through the history for the string of characters +between the start of the current line and the point. This +is a non-incremental search. By default, this command is unbound. +

+ + +

yank-nth-arg (M-C-y) +
+Insert the first argument to the previous command (usually +the second word on the previous line) at point. +With an argument n, +insert the nth word from the previous command (the words +in the previous command begin with word 0). A negative argument +inserts the nth word from the end of the previous command. +Once the argument n is computed, the argument is extracted +as if the `!n' history expansion had been specified. +

+ + +

yank-last-arg (M-. or M-_) +
+Insert last argument to the previous command (the last word of the +previous history entry). With an +argument, behave exactly like yank-nth-arg. +Successive calls to yank-last-arg move back through the history +list, inserting the last argument of each line in turn. +The history expansion facilities are used to extract the last argument, +as if the `!$' history expansion had been specified. +

+ +

+

+ + +

+ + + + + + + + + + + +
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+

8.4.3 Commands For Changing Text

+ +

+ +

+ +
delete-char (C-d) +
+Delete the character at point. If point is at the +beginning of the line, there are no characters in the line, and +the last character typed was not bound to delete-char, then +return EOF. +

+ + +

backward-delete-char (Rubout) +
+Delete the character behind the cursor. A numeric argument means +to kill the characters instead of deleting them. +

+ + +

forward-backward-delete-char () +
+Delete the character under the cursor, unless the cursor is at the +end of the line, in which case the character behind the cursor is +deleted. By default, this is not bound to a key. +

+ + +

quoted-insert (C-q or C-v) +
+Add the next character typed to the line verbatim. This is +how to insert key sequences like C-q, for example. +

+ + +

self-insert (a, b, A, 1, !, ...) +
+Insert yourself. +

+ + +

transpose-chars (C-t) +
+Drag the character before the cursor forward over +the character at the cursor, moving the +cursor forward as well. If the insertion point +is at the end of the line, then this +transposes the last two characters of the line. +Negative arguments have no effect. +

+ + +

transpose-words (M-t) +
+Drag the word before point past the word after point, +moving point past that word as well. +If the insertion point is at the end of the line, this transposes +the last two words on the line. +

+ + +

upcase-word (M-u) +
+Uppercase the current (or following) word. With a negative argument, +uppercase the previous word, but do not move the cursor. +

+ + +

downcase-word (M-l) +
+Lowercase the current (or following) word. With a negative argument, +lowercase the previous word, but do not move the cursor. +

+ + +

capitalize-word (M-c) +
+Capitalize the current (or following) word. With a negative argument, +capitalize the previous word, but do not move the cursor. +

+ + +

overwrite-mode () +
+Toggle overwrite mode. With an explicit positive numeric argument, +switches to overwrite mode. With an explicit non-positive numeric +argument, switches to insert mode. This command affects only +emacs mode; vi mode does overwrite differently. +Each call to readline() starts in insert mode. +

+ +In overwrite mode, characters bound to self-insert replace +the text at point rather than pushing the text to the right. +Characters bound to backward-delete-char replace the character +before point with a space. +

+ +By default, this command is unbound. +

+ +

+

+ + +

+ + + + + + + + + + + +
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+

8.4.4 Killing And Yanking

+ +

+ +

+ + +
kill-line (C-k) +
+Kill the text from point to the end of the line. +

+ + +

backward-kill-line (C-x Rubout) +
+Kill backward to the beginning of the line. +

+ + +

unix-line-discard (C-u) +
+Kill backward from the cursor to the beginning of the current line. +

+ + +

kill-whole-line () +
+Kill all characters on the current line, no matter where point is. +By default, this is unbound. +

+ + +

kill-word (M-d) +
+Kill from point to the end of the current word, or if between +words, to the end of the next word. +Word boundaries are the same as forward-word. +

+ + +

backward-kill-word (M-DEL) +
+Kill the word behind point. +Word boundaries are the same as backward-word. +

+ + +

unix-word-rubout (C-w) +
+Kill the word behind point, using white space as a word boundary. +The killed text is saved on the kill-ring. +

+ + +

unix-filename-rubout () +
+Kill the word behind point, using white space and the slash character +as the word boundaries. +The killed text is saved on the kill-ring. +

+ + +

delete-horizontal-space () +
+Delete all spaces and tabs around point. By default, this is unbound. +

+ + +

kill-region () +
+Kill the text in the current region. +By default, this command is unbound. +

+ + +

copy-region-as-kill () +
+Copy the text in the region to the kill buffer, so it can be yanked +right away. By default, this command is unbound. +

+ + +

copy-backward-word () +
+Copy the word before point to the kill buffer. +The word boundaries are the same as backward-word. +By default, this command is unbound. +

+ + +

copy-forward-word () +
+Copy the word following point to the kill buffer. +The word boundaries are the same as forward-word. +By default, this command is unbound. +

+ + +

yank (C-y) +
+Yank the top of the kill ring into the buffer at point. +

+ + +

yank-pop (M-y) +
+Rotate the kill-ring, and yank the new top. You can only do this if +the prior command is yank or yank-pop. +
+

+ + +

+ + + + + + + + + + + +
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+

8.4.5 Specifying Numeric Arguments

+ +
+ + +
digit-argument (M-0, M-1, ... M--) +
+Add this digit to the argument already accumulating, or start a new +argument. M-- starts a negative argument. +

+ + +

universal-argument () +
+This is another way to specify an argument. +If this command is followed by one or more digits, optionally with a +leading minus sign, those digits define the argument. +If the command is followed by digits, executing universal-argument +again ends the numeric argument, but is otherwise ignored. +As a special case, if this command is immediately followed by a +character that is neither a digit or minus sign, the argument count +for the next command is multiplied by four. +The argument count is initially one, so executing this function the +first time makes the argument count four, a second time makes the +argument count sixteen, and so on. +By default, this is not bound to a key. +
+

+ + +

+ + + + + + + + + + + +
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+

8.4.6 Letting Readline Type For You

+ +

+ +

+ +
complete (TAB) +
+Attempt to perform completion on the text before point. +The actual completion performed is application-specific. +Bash attempts completion treating the text as a variable (if the +text begins with `$'), username (if the text begins with +`~'), hostname (if the text begins with `@'), or +command (including aliases and functions) in turn. If none +of these produces a match, filename completion is attempted. +

+ + +

possible-completions (M-?) +
+List the possible completions of the text before point. +

+ + +

insert-completions (M-*) +
+Insert all completions of the text before point that would have +been generated by possible-completions. +

+ + +

menu-complete () +
+Similar to complete, but replaces the word to be completed +with a single match from the list of possible completions. +Repeated execution of menu-complete steps through the list +of possible completions, inserting each match in turn. +At the end of the list of completions, the bell is rung +(subject to the setting of bell-style) +and the original text is restored. +An argument of n moves n positions forward in the list +of matches; a negative argument may be used to move backward +through the list. +This command is intended to be bound to TAB, but is unbound +by default. +

+ + +

delete-char-or-list () +
+Deletes the character under the cursor if not at the beginning or +end of the line (like delete-char). +If at the end of the line, behaves identically to +possible-completions. +This command is unbound by default. +

+ + +

complete-filename (M-/) +
+Attempt filename completion on the text before point. +

+ + +

possible-filename-completions (C-x /) +
+List the possible completions of the text before point, +treating it as a filename. +

+ + +

complete-username (M-~) +
+Attempt completion on the text before point, treating +it as a username. +

+ + +

possible-username-completions (C-x ~) +
+List the possible completions of the text before point, +treating it as a username. +

+ + +

complete-variable (M-$) +
+Attempt completion on the text before point, treating +it as a shell variable. +

+ + +

possible-variable-completions (C-x $) +
+List the possible completions of the text before point, +treating it as a shell variable. +

+ + +

complete-hostname (M-@) +
+Attempt completion on the text before point, treating +it as a hostname. +

+ + +

possible-hostname-completions (C-x @) +
+List the possible completions of the text before point, +treating it as a hostname. +

+ + +

complete-command (M-!) +
+Attempt completion on the text before point, treating +it as a command name. Command completion attempts to +match the text against aliases, reserved words, shell +functions, shell builtins, and finally executable filenames, +in that order. +

+ + +

possible-command-completions (C-x !) +
+List the possible completions of the text before point, +treating it as a command name. +

+ + +

dynamic-complete-history (M-TAB) +
+Attempt completion on the text before point, comparing +the text against lines from the history list for possible +completion matches. +

+ + +

complete-into-braces (M-{) +
+Perform filename completion and insert the list of possible completions +enclosed within braces so the list is available to the shell +(see section 3.5.1 Brace Expansion). +

+ +

+

+ + +

+ + + + + + + + + + + +
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+

8.4.7 Keyboard Macros

+ +
+ + +
start-kbd-macro (C-x () +
+Begin saving the characters typed into the current keyboard macro. +

+ + +

end-kbd-macro (C-x )) +
+Stop saving the characters typed into the current keyboard macro +and save the definition. +

+ + +

call-last-kbd-macro (C-x e) +
+Re-execute the last keyboard macro defined, by making the characters +in the macro appear as if typed at the keyboard. +

+ +

+

+ + +

+ + + + + + + + + + + +
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+

8.4.8 Some Miscellaneous Commands

+ +
+ + +
re-read-init-file (C-x C-r) +
+Read in the contents of the inputrc file, and incorporate +any bindings or variable assignments found there. +

+ + +

abort (C-g) +
+Abort the current editing command and +ring the terminal's bell (subject to the setting of +bell-style). +

+ + +

do-uppercase-version (M-a, M-b, M-x, ...) +
+If the metafied character x is lowercase, run the command +that is bound to the corresponding uppercase character. +

+ + +

prefix-meta (ESC) +
+Metafy the next character typed. This is for keyboards +without a meta key. Typing `ESC f' is equivalent to typing +M-f. +

+ + +

undo (C-_ or C-x C-u) +
+Incremental undo, separately remembered for each line. +

+ + +

revert-line (M-r) +
+Undo all changes made to this line. This is like executing the undo +command enough times to get back to the beginning. +

+ + +

tilde-expand (M-&) +
+Perform tilde expansion on the current word. +

+ + +

set-mark (C-@) +
+Set the mark to the point. If a +numeric argument is supplied, the mark is set to that position. +

+ + +

exchange-point-and-mark (C-x C-x) +
+Swap the point with the mark. The current cursor position is set to +the saved position, and the old cursor position is saved as the mark. +

+ + +

character-search (C-]) +
+A character is read and point is moved to the next occurrence of that +character. A negative count searches for previous occurrences. +

+ + +

character-search-backward (M-C-]) +
+A character is read and point is moved to the previous occurrence +of that character. A negative count searches for subsequent +occurrences. +

+ + +

insert-comment (M-#) +
+Without a numeric argument, the value of the comment-begin +variable is inserted at the beginning of the current line. +If a numeric argument is supplied, this command acts as a toggle: if +the characters at the beginning of the line do not match the value +of comment-begin, the value is inserted, otherwise +the characters in comment-begin are deleted from the beginning of +the line. +In either case, the line is accepted as if a newline had been typed. +The default value of comment-begin causes this command +to make the current line a shell comment. +If a numeric argument causes the comment character to be removed, the line +will be executed by the shell. +

+ + +

dump-functions () +
+Print all of the functions and their key bindings to the +Readline output stream. If a numeric argument is supplied, +the output is formatted in such a way that it can be made part +of an inputrc file. This command is unbound by default. +

+ + +

dump-variables () +
+Print all of the settable variables and their values to the +Readline output stream. If a numeric argument is supplied, +the output is formatted in such a way that it can be made part +of an inputrc file. This command is unbound by default. +

+ + +

dump-macros () +
+Print all of the Readline key sequences bound to macros and the +strings they output. If a numeric argument is supplied, +the output is formatted in such a way that it can be made part +of an inputrc file. This command is unbound by default. +

+ + +

glob-complete-word (M-g) +
+The word before point is treated as a pattern for pathname expansion, +with an asterisk implicitly appended. This pattern is used to +generate a list of matching file names for possible completions. +

+ + +

glob-expand-word (C-x *) +
+The word before point is treated as a pattern for pathname expansion, +and the list of matching file names is inserted, replacing the word. +If a numeric argument is supplied, a `*' is appended before +pathname expansion. +

+ + +

glob-list-expansions (C-x g) +
+The list of expansions that would have been generated by +glob-expand-word is displayed, and the line is redrawn. +If a numeric argument is supplied, a `*' is appended before +pathname expansion. +

+ + +

display-shell-version (C-x C-v) +
+Display version information about the current instance of Bash. +

+ + +

shell-expand-line (M-C-e) +
+Expand the line as the shell does. +This performs alias and history expansion as well as all of the shell +word expansions (see section 3.5 Shell Expansions). +

+ + +

history-expand-line (M-^) +
+Perform history expansion on the current line. +

+ + +

magic-space () +
+Perform history expansion on the current line and insert a space +(see section 9.3 History Expansion). +

+ + +

alias-expand-line () +
+Perform alias expansion on the current line (see section 6.6 Aliases). +

+ + +

history-and-alias-expand-line () +
+Perform history and alias expansion on the current line. +

+ + +

insert-last-argument (M-. or M-_) +
+A synonym for yank-last-arg. +

+ + +

operate-and-get-next (C-o) +
+Accept the current line for execution and fetch the next line +relative to the current line from the history for editing. Any +argument is ignored. +

+ + +

edit-and-execute-command (C-xC-e) +
+Invoke an editor on the current command line, and execute the result as shell +commands. +Bash attempts to invoke +$VISUAL, $EDITOR, and emacs +as the editor, in that order. +

+ +

+

+ + +

+ + + + + + + + + + + +
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+

8.5 Readline vi Mode

+ +

+ +While the Readline library does not have a full set of vi +editing functions, it does contain enough to allow simple editing +of the line. The Readline vi mode behaves as specified in +the POSIX 1003.2 standard. +

+ +In order to switch interactively between emacs and vi +editing modes, use the `set -o emacs' and `set -o vi' +commands (see section 4.3.1 The Set Builtin). +The Readline default is emacs mode. +

+ +When you enter a line in vi mode, you are already placed in +`insertion' mode, as if you had typed an `i'. Pressing ESC +switches you into `command' mode, where you can edit the text of the +line with the standard vi movement keys, move to previous +history lines with `k' and subsequent lines with `j', and +so forth. +

+ + +

+ + + + + + + + + + + +
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+

8.6 Programmable Completion

+ +

+ +When word completion is attempted for an argument to a command for +which a completion specification (a compspec) has been defined +using the complete builtin (see section 8.7 Programmable Completion Builtins), +the programmable completion facilities are invoked. +

+ +First, the command name is identified. +If a compspec has been defined for that command, the +compspec is used to generate the list of possible completions for the word. +If the command word is a full pathname, a compspec for the full +pathname is searched for first. +If no compspec is found for the full pathname, an attempt is made to +find a compspec for the portion following the final slash. +

+ +Once a compspec has been found, it is used to generate the list of +matching words. +If a compspec is not found, the default Bash completion +described above (see section 8.4.6 Letting Readline Type For You) is performed. +

+ +First, the actions specified by the compspec are used. +Only matches which are prefixed by the word being completed are +returned. +When the `-f' or `-d' option is used for filename or +directory name completion, the shell variable FIGNORE is +used to filter the matches. +See section 5.2 Bash Variables, for a description of FIGNORE. +

+ +Any completions specified by a filename expansion pattern to the +`-G' option are generated next. +The words generated by the pattern need not match the word being completed. +The GLOBIGNORE shell variable is not used to filter the matches, +but the FIGNORE shell variable is used. +

+ +Next, the string specified as the argument to the `-W' option +is considered. +The string is first split using the characters in the IFS +special variable as delimiters. +Shell quoting is honored. +Each word is then expanded using +brace expansion, tilde expansion, parameter and variable expansion, +command substitution, and arithmetic expansion, +as described above (see section 3.5 Shell Expansions). +The results are split using the rules described above +(see section 3.5.7 Word Splitting). +The results of the expansion are prefix-matched against the word being +completed, and the matching words become the possible completions. +

+ +After these matches have been generated, any shell function or command +specified with the `-F' and `-C' options is invoked. +When the command or function is invoked, the COMP_LINE, +COMP_POINT, COMP_KEY, and COMP_TYPE variables are +assigned values as described above (see section 5.2 Bash Variables). +If a shell function is being invoked, the COMP_WORDS and +COMP_CWORD variables are also set. +When the function or command is invoked, the first argument is the +name of the command whose arguments are being completed, the +second argument is the word being completed, and the third argument +is the word preceding the word being completed on the current command line. +No filtering of the generated completions against the word being completed +is performed; the function or command has complete freedom in generating +the matches. +

+ +Any function specified with `-F' is invoked first. +The function may use any of the shell facilities, including the +compgen builtin described below +(see section 8.7 Programmable Completion Builtins), to generate the matches. +It must put the possible completions in the COMPREPLY array +variable. +

+ +Next, any command specified with the `-C' option is invoked +in an environment equivalent to command substitution. +It should print a list of completions, one per line, to +the standard output. +Backslash may be used to escape a newline, if necessary. +

+ +After all of the possible completions are generated, any filter +specified with the `-X' option is applied to the list. +The filter is a pattern as used for pathname expansion; a `&' +in the pattern is replaced with the text of the word being completed. +A literal `&' may be escaped with a backslash; the backslash +is removed before attempting a match. +Any completion that matches the pattern will be removed from the list. +A leading `!' negates the pattern; in this case any completion +not matching the pattern will be removed. +

+ +Finally, any prefix and suffix specified with the `-P' and `-S' +options are added to each member of the completion list, and the result is +returned to the Readline completion code as the list of possible +completions. +

+ +If the previously-applied actions do not generate any matches, and the +`-o dirnames' option was supplied to complete when the +compspec was defined, directory name completion is attempted. +

+ +If the `-o plusdirs' option was supplied to complete when +the compspec was defined, directory name completion is attempted and any +matches are added to the results of the other actions. +

+ +By default, if a compspec is found, whatever it generates is returned to +the completion code as the full set of possible completions. +The default Bash completions are not attempted, and the Readline default +of filename completion is disabled. +If the `-o bashdefault' option was supplied to complete when +the compspec was defined, the default Bash completions are attempted +if the compspec generates no matches. +If the `-o default' option was supplied to complete when the +compspec was defined, Readline's default completion will be performed +if the compspec (and, if attempted, the default Bash completions) +generate no matches. +

+ +When a compspec indicates that directory name completion is desired, +the programmable completion functions force Readline to append a slash +to completed names which are symbolic links to directories, subject to +the value of the mark-directories Readline variable, regardless +of the setting of the mark-symlinked-directories Readline variable. +

+ + +

+ + + + + + + + + + + +
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+

8.7 Programmable Completion Builtins

+ +

+ +Two builtin commands are available to manipulate the programmable completion +facilities. +

+ +

+
compgen +
+
 
compgen [option] [word]
+

+ +Generate possible completion matches for word according to +the options, which may be any option accepted by the +complete +builtin with the exception of `-p' and `-r', and write +the matches to the standard output. +When using the `-F' or `-C' options, the various shell variables +set by the programmable completion facilities, while available, will not +have useful values. +

+ +The matches will be generated in the same way as if the programmable +completion code had generated them directly from a completion specification +with the same flags. +If word is specified, only those completions matching word +will be displayed. +

+ +The return value is true unless an invalid option is supplied, or no +matches were generated. +

+ +

complete +
+
 
complete [-abcdefgjksuv] [-o comp-option] [-A action] [-G globpat] [-W wordlist]
+[-F function] [-C command] [-X filterpat]
+[-P prefix] [-S suffix] name [name ...]
+complete -pr [name ...]
+

+ +Specify how arguments to each name should be completed. +If the `-p' option is supplied, or if no options are supplied, existing +completion specifications are printed in a way that allows them to be +reused as input. +The `-r' option removes a completion specification for +each name, or, if no names are supplied, all +completion specifications. +

+ +The process of applying these completion specifications when word completion +is attempted is described above (see section 8.6 Programmable Completion). +

+ +Other options, if specified, have the following meanings. +The arguments to the `-G', `-W', and `-X' options +(and, if necessary, the `-P' and `-S' options) +should be quoted to protect them from expansion before the +complete builtin is invoked. +

+ +

+
-o comp-option +
The comp-option controls several aspects of the compspec's behavior +beyond the simple generation of completions. +comp-option may be one of: +

+ +

+ +
bashdefault +
Perform the rest of the default Bash completions if the compspec +generates no matches. +

+ +

default +
Use Readline's default filename completion if the compspec generates +no matches. +

+ +

dirnames +
Perform directory name completion if the compspec generates no matches. +

+ +

filenames +
Tell Readline that the compspec generates filenames, so it can perform any +filename-specific processing (like adding a slash to directory names or +suppressing trailing spaces). This option is intended to be used with +shell functions specified with `-F'. +

+ +

nospace +
Tell Readline not to append a space (the default) to words completed at +the end of the line. +

+ +

plusdirs +
After any matches defined by the compspec are generated, +directory name completion is attempted and any +matches are added to the results of the other actions. +

+ +

+

+ +

-A action +
The action may be one of the following to generate a list of possible +completions: +

+ +

+
alias +
Alias names. May also be specified as `-a'. +

+ +

arrayvar +
Array variable names. +

+ +

binding +
Readline key binding names (see section 8.4 Bindable Readline Commands). +

+ +

builtin +
Names of shell builtin commands. May also be specified as `-b'. +

+ +

command +
Command names. May also be specified as `-c'. +

+ +

directory +
Directory names. May also be specified as `-d'. +

+ +

disabled +
Names of disabled shell builtins. +

+ +

enabled +
Names of enabled shell builtins. +

+ +

export +
Names of exported shell variables. May also be specified as `-e'. +

+ +

file +
File names. May also be specified as `-f'. +

+ +

function +
Names of shell functions. +

+ +

group +
Group names. May also be specified as `-g'. +

+ +

helptopic +
Help topics as accepted by the help builtin (see section 4.2 Bash Builtin Commands). +

+ +

hostname +
Hostnames, as taken from the file specified by the +HOSTFILE shell variable (see section 5.2 Bash Variables). +

+ +

job +
Job names, if job control is active. May also be specified as `-j'. +

+ +

keyword +
Shell reserved words. May also be specified as `-k'. +

+ +

running +
Names of running jobs, if job control is active. +

+ +

service +
Service names. May also be specified as `-s'. +

+ +

setopt +
Valid arguments for the `-o' option to the set builtin +(see section 4.3.1 The Set Builtin). +

+ +

shopt +
Shell option names as accepted by the shopt builtin +(see section 4.2 Bash Builtin Commands). +

+ +

signal +
Signal names. +

+ +

stopped +
Names of stopped jobs, if job control is active. +

+ +

user +
User names. May also be specified as `-u'. +

+ +

variable +
Names of all shell variables. May also be specified as `-v'. +
+

+ +

-G globpat +
The filename expansion pattern globpat is expanded to generate +the possible completions. +

+ +

-W wordlist +
The wordlist is split using the characters in the +IFS special variable as delimiters, and each resultant word +is expanded. +The possible completions are the members of the resultant list which +match the word being completed. +

+ +

-C command +
command is executed in a subshell environment, and its output is +used as the possible completions. +

+ +

-F function +
The shell function function is executed in the current shell +environment. +When it finishes, the possible completions are retrieved from the value +of the COMPREPLY array variable. +

+ +

-X filterpat +
filterpat is a pattern as used for filename expansion. +It is applied to the list of possible completions generated by the +preceding options and arguments, and each completion matching +filterpat is removed from the list. +A leading `!' in filterpat negates the pattern; in this +case, any completion not matching filterpat is removed. +

+ +

-P prefix +
prefix is added at the beginning of each possible completion +after all other options have been applied. +

+ +

-S suffix +
suffix is appended to each possible completion +after all other options have been applied. +
+

+ +The return value is true unless an invalid option is supplied, an option +other than `-p' or `-r' is supplied without a name +argument, an attempt is made to remove a completion specification for +a name for which no specification exists, or +an error occurs adding a completion specification. +

+ +

+ +

+ + +

+ + + + + + + + + + + +
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+

9. Using History Interactively

+ +

+ +This chapter describes how to use the GNU History Library +interactively, from a user's standpoint. +It should be considered a user's guide. +For information on using the GNU History Library in other programs, +see the GNU Readline Library Manual. +

+ +

+ + + +
9.1 Bash History Facilities  How Bash lets you manipulate your command + history.
9.2 Bash History Builtins  The Bash builtin commands that manipulate + the command history.
9.3 History Expansion  What it feels like using History as a user.
+

+ + +

+ + + + + + + + + + + +
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+

9.1 Bash History Facilities

+ +

+ +When the `-o history' option to the set builtin +is enabled (see section 4.3.1 The Set Builtin), +the shell provides access to the command history, +the list of commands previously typed. +The value of the HISTSIZE shell variable is used as the +number of commands to save in a history list. +The text of the last $HISTSIZE +commands (default 500) is saved. +The shell stores each command in the history list prior to +parameter and variable expansion +but after history expansion is performed, subject to the +values of the shell variables +HISTIGNORE and HISTCONTROL. +

+ +When the shell starts up, the history is initialized from the +file named by the HISTFILE variable (default `~/.bash_history'). +The file named by the value of HISTFILE is truncated, if +necessary, to contain no more than the number of lines specified by +the value of the HISTFILESIZE variable. +When an interactive shell exits, the last +$HISTSIZE lines are copied from the history list to the file +named by $HISTFILE. +If the histappend shell option is set (see section 4.2 Bash Builtin Commands), +the lines are appended to the history file, +otherwise the history file is overwritten. +If HISTFILE +is unset, or if the history file is unwritable, the history is +not saved. After saving the history, the history file is truncated +to contain no more than $HISTFILESIZE +lines. If HISTFILESIZE is not set, no truncation is performed. +

+ +If the HISTTIMEFORMAT is set, the time stamp information +associated with each history entry is written to the history file. +

+ +The builtin command fc may be used to list or edit and re-execute +a portion of the history list. +The history builtin may be used to display or modify the history +list and manipulate the history file. +When using command-line editing, search commands +are available in each editing mode that provide access to the +history list (see section 8.4.2 Commands For Manipulating The History). +

+ +The shell allows control over which commands are saved on the history +list. The HISTCONTROL and HISTIGNORE +variables may be set to cause the shell to save only a subset of the +commands entered. +The cmdhist +shell option, if enabled, causes the shell to attempt to save each +line of a multi-line command in the same history entry, adding +semicolons where necessary to preserve syntactic correctness. +The lithist +shell option causes the shell to save the command with embedded newlines +instead of semicolons. +The shopt builtin is used to set these options. +See section 4.2 Bash Builtin Commands, for a description of shopt. +

+ + +

+ + + + + + + + + + + +
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+

9.2 Bash History Builtins

+ +

+ +Bash provides two builtin commands which manipulate the +history list and history file. +

+ +

+ +
fc +
+
 
fc [-e ename] [-lnr] [first] [last]
+fc -s [pat=rep] [command]
+

+ +Fix Command. In the first form, a range of commands from first to +last is selected from the history list. Both first and +last may be specified as a string (to locate the most recent +command beginning with that string) or as a number (an index into the +history list, where a negative number is used as an offset from the +current command number). If last is not specified it is set to +first. If first is not specified it is set to the previous +command for editing and -16 for listing. If the `-l' flag is +given, the commands are listed on standard output. The `-n' flag +suppresses the command numbers when listing. The `-r' flag +reverses the order of the listing. Otherwise, the editor given by +ename is invoked on a file containing those commands. If +ename is not given, the value of the following variable expansion +is used: ${FCEDIT:-${EDITOR:-vi}}. This says to use the +value of the FCEDIT variable if set, or the value of the +EDITOR variable if that is set, or vi if neither is set. +When editing is complete, the edited commands are echoed and executed. +

+ +In the second form, command is re-executed after each instance +of pat in the selected command is replaced by rep. +

+ +A useful alias to use with the fc command is r='fc -s', so +that typing `r cc' runs the last command beginning with cc +and typing `r' re-executes the last command (see section 6.6 Aliases). +

+ +

history +
+
 
history [n]
+history -c
+history -d offset
+history [-anrw] [filename]
+history -ps arg
+

+ +With no options, display the history list with line numbers. +Lines prefixed with a `*' have been modified. +An argument of n lists only the last n lines. +If the shell variable HISTTIMEFORMAT is set and not null, +it is used as a format string for strftime to display +the time stamp associated with each displayed history entry. +No intervening blank is printed between the formatted time stamp +and the history line. +

+ +Options, if supplied, have the following meanings: +

+ +

+
-c +
Clear the history list. This may be combined +with the other options to replace the history list completely. +

+ +

-d offset +
Delete the history entry at position offset. +offset should be specified as it appears when the history is +displayed. +

+ +

-a +
Append the new +history lines (history lines entered since the beginning of the +current Bash session) to the history file. +

+ +

-n +
Append the history lines not already read from the history file +to the current history list. These are lines appended to the history +file since the beginning of the current Bash session. +

+ +

-r +
Read the current history file and append its contents to +the history list. +

+ +

-w +
Write out the current history to the history file. +

+ +

-p +
Perform history substitution on the args and display the result +on the standard output, without storing the results in the history list. +

+ +

-s +
The args are added to the end of +the history list as a single entry. +

+ +

+

+ +When any of the `-w', `-r', `-a', or `-n' options is +used, if filename +is given, then it is used as the history file. If not, then +the value of the HISTFILE variable is used. +

+ +

+

+ + +

+ + + + + + + + + + + +
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+

9.3 History Expansion

+ +

+ +The History library provides a history expansion feature that is similar +to the history expansion provided by csh. This section +describes the syntax used to manipulate the history information. +

+ +History expansions introduce words from the history list into +the input stream, making it easy to repeat commands, insert the +arguments to a previous command into the current input line, or +fix errors in previous commands quickly. +

+ +History expansion takes place in two parts. The first is to determine +which line from the history list should be used during substitution. +The second is to select portions of that line for inclusion into the +current one. The line selected from the history is called the +event, and the portions of that line that are acted upon are +called words. Various modifiers are available to manipulate +the selected words. The line is broken into words in the same fashion +that Bash does, so that several words +surrounded by quotes are considered one word. +History expansions are introduced by the appearance of the +history expansion character, which is `!' by default. +Only `\' and `'' may be used to escape the history expansion +character. +

+ +Several shell options settable with the shopt +builtin (see section 4.2 Bash Builtin Commands) may be used to tailor +the behavior of history expansion. If the +histverify shell option is enabled, and Readline +is being used, history substitutions are not immediately passed to +the shell parser. +Instead, the expanded line is reloaded into the Readline +editing buffer for further modification. +If Readline is being used, and the histreedit +shell option is enabled, a failed history expansion will be +reloaded into the Readline editing buffer for correction. +The `-p' option to the history builtin command +may be used to see what a history expansion will do before using it. +The `-s' option to the history builtin may be used to +add commands to the end of the history list without actually executing +them, so that they are available for subsequent recall. +This is most useful in conjunction with Readline. +

+ +The shell allows control of the various characters used by the +history expansion mechanism with the histchars variable. +

+ +

+ + + +
9.3.1 Event Designators  How to specify which history line to use.
9.3.2 Word Designators  Specifying which words are of interest.
9.3.3 Modifiers  Modifying the results of substitution.
+

+ + +

+ + + + + + + + + + + +
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+

9.3.1 Event Designators

+ +

+ +An event designator is a reference to a command line entry in the +history list. + +

+ +

+ +
! +
Start a history substitution, except when followed by a space, tab, +the end of the line, `=' or `(' (when the +extglob shell option is enabled using the shopt builtin). +

+ +

!n +
Refer to command line n. +

+ +

!-n +
Refer to the command n lines back. +

+ +

!! +
Refer to the previous command. This is a synonym for `!-1'. +

+ +

!string +
Refer to the most recent command starting with string. +

+ +

!?string[?] +
Refer to the most recent command containing string. The trailing +`?' may be omitted if the string is followed immediately by +a newline. +

+ +

^string1^string2^ +
Quick Substitution. Repeat the last command, replacing string1 +with string2. Equivalent to +!!:s/string1/string2/. +

+ +

!# +
The entire command line typed so far. +

+ +

+

+ + +

+ + + + + + + + + + + +
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+

9.3.2 Word Designators

+ +

+ +Word designators are used to select desired words from the event. +A `:' separates the event specification from the word designator. It +may be omitted if the word designator begins with a `^', `$', +`*', `-', or `%'. Words are numbered from the beginning +of the line, with the first word being denoted by 0 (zero). Words are +inserted into the current line separated by single spaces. +

+ +For example, +

+ +

+
!! +
designates the preceding command. When you type this, the preceding +command is repeated in toto. +

+ +

!!:$ +
designates the last argument of the preceding command. This may be +shortened to !$. +

+ +

!fi:2 +
designates the second argument of the most recent command starting with +the letters fi. +
+

+ +Here are the word designators: + +

+ +
0 (zero) +
The 0th word. For many applications, this is the command word. +

+ +

n +
The nth word. +

+ +

^ +
The first argument; that is, word 1. +

+ +

$ +
The last argument. +

+ +

% +
The word matched by the most recent `?string?' search. +

+ +

x-y +
A range of words; `-y' abbreviates `0-y'. +

+ +

* +
All of the words, except the 0th. This is a synonym for `1-$'. +It is not an error to use `*' if there is just one word in the event; +the empty string is returned in that case. +

+ +

x* +
Abbreviates `x-$' +

+ +

x- +
Abbreviates `x-$' like `x*', but omits the last word. +

+ +

+

+ +If a word designator is supplied without an event specification, the +previous command is used as the event. +

+ + +

+ + + + + + + + + + + +
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+

9.3.3 Modifiers

+ +

+ +After the optional word designator, you can add a sequence of one or more +of the following modifiers, each preceded by a `:'. +

+ +

+ +
h +
Remove a trailing pathname component, leaving only the head. +

+ +

t +
Remove all leading pathname components, leaving the tail. +

+ +

r +
Remove a trailing suffix of the form `.suffix', leaving +the basename. +

+ +

e +
Remove all but the trailing suffix. +

+ +

p +
Print the new command but do not execute it. +

+ +

q +
Quote the substituted words, escaping further substitutions. +

+ +

x +
Quote the substituted words as with `q', +but break into words at spaces, tabs, and newlines. +

+ +

s/old/new/ +
Substitute new for the first occurrence of old in the +event line. Any delimiter may be used in place of `/'. +The delimiter may be quoted in old and new +with a single backslash. If `&' appears in new, +it is replaced by old. A single backslash will quote +the `&'. The final delimiter is optional if it is the last +character on the input line. +

+ +

& +
Repeat the previous substitution. +

+ +

g +
a +
Cause changes to be applied over the entire event line. Used in +conjunction with `s', as in gs/old/new/, +or with `&'. +

+ +

G +
Apply the following `s' modifier once to each word in the event. +

+ +

+

+ + +

+ + + + + + + + + + + +
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+

10. Installing Bash

+ +

+ +This chapter provides basic instructions for installing Bash on +the various supported platforms. The distribution supports the +GNU operating systems, nearly every version of Unix, and several +non-Unix systems such as BeOS and Interix. +Other independent ports exist for +MS-DOS, OS/2, and Windows platforms. +

+ +

+ + + + + + + + +
10.1 Basic Installation  Installation instructions.
10.2 Compilers and Options  How to set special options for various + systems.
10.3 Compiling For Multiple Architectures  How to compile Bash for more + than one kind of system from + the same source tree.
10.4 Installation Names  How to set the various paths used by the installation.
10.5 Specifying the System Type  How to configure Bash for a particular system.
10.6 Sharing Defaults  How to share default configuration values among GNU + programs.
10.7 Operation Controls  Options recognized by the configuration program.
10.8 Optional Features  How to enable and disable optional features when + building Bash.
+

+ + +

+ + + + + + + + + + + +
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+

10.1 Basic Installation

+ +

+ +These are installation instructions for Bash. +

+ +The simplest way to compile Bash is: +

+ +

    +
  1. +cd to the directory containing the source code and type +`./configure' to configure Bash for your system. If you're +using csh on an old version of System V, you might need to +type `sh ./configure' instead to prevent csh from trying +to execute configure itself. +

    + +Running configure takes some time. +While running, it prints messages telling which features it is +checking for. +

    + +

  2. +Type `make' to compile Bash and build the bashbug bug +reporting script. +

    + +

  3. +Optionally, type `make tests' to run the Bash test suite. +

    + +

  4. +Type `make install' to install bash and bashbug. +This will also install the manual pages and Info file. +

    + +

+

+ +The configure shell script attempts to guess correct +values for various system-dependent variables used during +compilation. It uses those values to create a `Makefile' in +each directory of the package (the top directory, the +`builtins', `doc', and `support' directories, +each directory under `lib', and several others). It also creates a +`config.h' file containing system-dependent definitions. +Finally, it creates a shell script named config.status that you +can run in the future to recreate the current configuration, a +file `config.cache' that saves the results of its tests to +speed up reconfiguring, and a file `config.log' containing +compiler output (useful mainly for debugging configure). +If at some point +`config.cache' contains results you don't want to keep, you +may remove or edit it. +

+ +To find out more about the options and arguments that the +configure script understands, type +

+ +
 
bash-2.04$ ./configure --help
+

+ +at the Bash prompt in your Bash source directory. +

+ +If you need to do unusual things to compile Bash, please +try to figure out how configure could check whether or not +to do them, and mail diffs or instructions to +bash-maintainers@gnu.org so they can be +considered for the next release. +

+ +The file `configure.in' is used to create configure +by a program called Autoconf. You only need +`configure.in' if you want to change it or regenerate +configure using a newer version of Autoconf. If +you do this, make sure you are using Autoconf version 2.50 or +newer. +

+ +You can remove the program binaries and object files from the +source code directory by typing `make clean'. To also remove the +files that configure created (so you can compile Bash for +a different kind of computer), type `make distclean'. +

+ + +

+ + + + + + + + + + + +
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+

10.2 Compilers and Options

+ +

+ +Some systems require unusual options for compilation or linking +that the configure script does not know about. You can +give configure initial values for variables by setting +them in the environment. Using a Bourne-compatible shell, you +can do that on the command line like this: +

+ +
 
CC=c89 CFLAGS=-O2 LIBS=-lposix ./configure
+

+ +On systems that have the env program, you can do it like this: +

+ +
 
env CPPFLAGS=-I/usr/local/include LDFLAGS=-s ./configure
+

+ +The configuration process uses GCC to build Bash if it +is available. +

+ + +

+ + + + + + + + + + + +
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+

10.3 Compiling For Multiple Architectures

+ +

+ +You can compile Bash for more than one kind of computer at the +same time, by placing the object files for each architecture in their +own directory. To do this, you must use a version of make that +supports the VPATH variable, such as GNU make. +cd to the +directory where you want the object files and executables to go and run +the configure script from the source directory. You may need to +supply the `--srcdir=PATH' argument to tell configure where the +source files are. configure automatically checks for the +source code in the directory that configure is in and in `..'. +

+ +If you have to use a make that does not supports the VPATH +variable, you can compile Bash for one architecture at a +time in the source code directory. After you have installed +Bash for one architecture, use `make distclean' before +reconfiguring for another architecture. +

+ +Alternatively, if your system supports symbolic links, you can use the +`support/mkclone' script to create a build tree which has +symbolic links back to each file in the source directory. Here's an +example that creates a build directory in the current directory from a +source directory `/usr/gnu/src/bash-2.0': +

+ +
 
bash /usr/gnu/src/bash-2.0/support/mkclone -s /usr/gnu/src/bash-2.0 .
+

+ +The mkclone script requires Bash, so you must have already built +Bash for at least one architecture before you can create build +directories for other architectures. +

+ + +

+ + + + + + + + + + + +
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+

10.4 Installation Names

+ +

+ +By default, `make install' will install into +`/usr/local/bin', `/usr/local/man', etc. You can +specify an installation prefix other than `/usr/local' by +giving configure the option `--prefix=PATH', +or by specifying a value for the DESTDIR `make' +variable when running `make install'. +

+ +You can specify separate installation prefixes for +architecture-specific files and architecture-independent files. +If you give configure the option +`--exec-prefix=PATH', `make install' will use +PATH as the prefix for installing programs and libraries. +Documentation and other data files will still use the regular prefix. +

+ + +

+ + + + + + + + + + + +
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+

10.5 Specifying the System Type

+ +

+ +There may be some features configure can not figure out +automatically, but need to determine by the type of host Bash +will run on. Usually configure can figure that +out, but if it prints a message saying it can not guess the host +type, give it the `--host=TYPE' option. `TYPE' can +either be a short name for the system type, such as `sun4', +or a canonical name with three fields: `CPU-COMPANY-SYSTEM' +(e.g., `i386-unknown-freebsd4.2'). +

+ +See the file `support/config.sub' for the possible +values of each field. +

+ + +

+ + + + + + + + + + + +
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+

10.6 Sharing Defaults

+ +

+ +If you want to set default values for configure scripts to +share, you can create a site shell script called +config.site that gives default values for variables like +CC, cache_file, and prefix. configure +looks for `PREFIX/share/config.site' if it exists, then +`PREFIX/etc/config.site' if it exists. Or, you can set the +CONFIG_SITE environment variable to the location of the site +script. A warning: the Bash configure looks for a site script, +but not all configure scripts do. +

+ + +

+ + + + + + + + + + + +
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+

10.7 Operation Controls

+ +

+ +configure recognizes the following options to control how it +operates. +

+ +

+ +
--cache-file=file +
Use and save the results of the tests in +file instead of `./config.cache'. Set file to +`/dev/null' to disable caching, for debugging +configure. +

+ +

--help +
Print a summary of the options to configure, and exit. +

+ +

--quiet +
--silent +
-q +
Do not print messages saying which checks are being made. +

+ +

--srcdir=dir +
Look for the Bash source code in directory dir. Usually +configure can determine that directory automatically. +

+ +

--version +
Print the version of Autoconf used to generate the configure +script, and exit. +
+

+ +configure also accepts some other, not widely used, boilerplate +options. `configure --help' prints the complete list. +

+ + +

+ + + + + + + + + + + +
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+

10.8 Optional Features

+ +

+ +The Bash configure has a number of `--enable-feature' +options, where feature indicates an optional part of Bash. +There are also several `--with-package' options, +where package is something like `bash-malloc' or `purify'. +To turn off the default use of a package, use +`--without-package'. To configure Bash without a feature +that is enabled by default, use `--disable-feature'. +

+ +Here is a complete list of the `--enable-' and +`--with-' options that the Bash configure recognizes. +

+ +

+
--with-afs +
Define if you are using the Andrew File System from Transarc. +

+ +

--with-bash-malloc +
Use the Bash version of +malloc in the directory `lib/malloc'. This is not the same +malloc that appears in GNU libc, but an older version +originally derived from the 4.2 BSD malloc. This malloc +is very fast, but wastes some space on each allocation. +This option is enabled by default. +The `NOTES' file contains a list of systems for +which this should be turned off, and configure disables this +option automatically for a number of systems. +

+ +

--with-curses +
Use the curses library instead of the termcap library. This should +be supplied if your system has an inadequate or incomplete termcap +database. +

+ +

--with-gnu-malloc +
A synonym for --with-bash-malloc. +

+ +

--with-installed-readline[=PREFIX] +
Define this to make Bash link with a locally-installed version of Readline +rather than the version in `lib/readline'. This works only with +Readline 5.0 and later versions. If PREFIX is yes or not +supplied, configure uses the values of the make variables +includedir and libdir, which are subdirectories of prefix +by default, to find the installed version of Readline if it is not in +the standard system include and library directories. +If PREFIX is no, Bash links with the version in +`lib/readline'. +If PREFIX is set to any other value, configure treats it as +a directory pathname and looks for +the installed version of Readline in subdirectories of that directory +(include files in PREFIX/include and the library in +PREFIX/lib). +

+ +

--with-purify +
Define this to use the Purify memory allocation checker from Rational +Software. +

+ +

--enable-minimal-config +
This produces a shell with minimal features, close to the historical +Bourne shell. +
+

+ +There are several `--enable-' options that alter how Bash is +compiled and linked, rather than changing run-time features. +

+ +

+
--enable-largefile +
Enable support for large files if the operating system requires special compiler options +to build programs which can access large files. This is enabled by +default, if the operating system provides large file support. +

+ +

--enable-profiling +
This builds a Bash binary that produces profiling information to be +processed by gprof each time it is executed. +

+ +

--enable-static-link +
This causes Bash to be linked statically, if gcc is being used. +This could be used to build a version to use as root's shell. +
+

+ +The `minimal-config' option can be used to disable all of +the following options, but it is processed first, so individual +options may be enabled using `enable-feature'. +

+ +All of the following options except for `disabled-builtins' and +`xpg-echo-default' are +enabled by default, unless the operating system does not provide the +necessary support. +

+ +

+
--enable-alias +
Allow alias expansion and include the alias and unalias +builtins (see section 6.6 Aliases). +

+ +

--enable-arith-for-command +
Include support for the alternate form of the for command +that behaves like the C language for statement +(see section 3.2.4.1 Looping Constructs). +

+ +

--enable-array-variables +
Include support for one-dimensional array shell variables +(see section 6.7 Arrays). +

+ +

--enable-bang-history +
Include support for csh-like history substitution +(see section 9.3 History Expansion). +

+ +

--enable-brace-expansion +
Include csh-like brace expansion +( b{a,b}c ==> bac bbc ). +See 3.5.1 Brace Expansion, for a complete description. +

+ +

--enable-command-timing +
Include support for recognizing time as a reserved word and for +displaying timing statistics for the pipeline following time +(see section 3.2.2 Pipelines). +This allows pipelines as well as shell builtins and functions to be timed. +

+ +

--enable-cond-command +
Include support for the [[ conditional command. +(see section 3.2.4.2 Conditional Constructs). +

+ +

--enable-cond-regexp +
Include support for matching POSIX regular expressions using the +`=~' binary operator in the [[ conditional command. +(see section 3.2.4.2 Conditional Constructs). +

+ +

--enable-debugger +
Include support for the bash debugger (distributed separately). +

+ +

--enable-directory-stack +
Include support for a csh-like directory stack and the +pushd, popd, and dirs builtins +(see section 6.8 The Directory Stack). +

+ +

--enable-disabled-builtins +
Allow builtin commands to be invoked via `builtin xxx' +even after xxx has been disabled using `enable -n xxx'. +See 4.2 Bash Builtin Commands, for details of the builtin and +enable builtin commands. +

+ +

--enable-dparen-arithmetic +
Include support for the ((...)) command +(see section 3.2.4.2 Conditional Constructs). +

+ +

--enable-extended-glob +
Include support for the extended pattern matching features described +above under 3.5.8.1 Pattern Matching. +

+ +

--enable-help-builtin +
Include the help builtin, which displays help on shell builtins and +variables (see section 4.2 Bash Builtin Commands). +

+ +

--enable-history +
Include command history and the fc and history +builtin commands (see section 9.1 Bash History Facilities). +

+ +

--enable-job-control +
This enables the job control features (see section 7. Job Control), +if the operating system supports them. +

+ +

--enable-multibyte +
This enables support for multibyte characters if the operating +system provides the necessary support. +

+ +

--enable-net-redirections +
This enables the special handling of filenames of the form +/dev/tcp/host/port and +/dev/udp/host/port +when used in redirections (see section 3.6 Redirections). +

+ +

--enable-process-substitution +
This enables process substitution (see section 3.5.6 Process Substitution) if +the operating system provides the necessary support. +

+ +

--enable-progcomp +
Enable the programmable completion facilities +(see section 8.6 Programmable Completion). +If Readline is not enabled, this option has no effect. +

+ +

--enable-prompt-string-decoding +
Turn on the interpretation of a number of backslash-escaped characters +in the $PS1, $PS2, $PS3, and $PS4 prompt +strings. See 6.9 Controlling the Prompt, for a complete list of prompt +string escape sequences. +

+ +

--enable-readline +
Include support for command-line editing and history with the Bash +version of the Readline library (see section 8. Command Line Editing). +

+ +

--enable-restricted +
Include support for a restricted shell. If this is enabled, Bash, +when called as rbash, enters a restricted mode. See +6.10 The Restricted Shell, for a description of restricted mode. +

+ +

--enable-select +
Include the select builtin, which allows the generation of simple +menus (see section 3.2.4.2 Conditional Constructs). +

+ +

--enable-separate-helpfiles +
Use external files for the documentation displayed by the help builtin +instead of storing the text internally. +

+ +

--enable-single-help-strings +
Store the text displayed by the help builtin as a single string for +each help topic. This aids in translating the text to different languages. +You may need to disable this if your compiler cannot handle very long string +literals. +

+ +

--enable-strict-posix-default +
Make Bash POSIX-conformant by default (see section 6.11 Bash POSIX Mode). +

+ +

--enable-usg-echo-default +
A synonym for --enable-xpg-echo-default. +

+ +

--enable-xpg-echo-default +
Make the echo builtin expand backslash-escaped characters by default, +without requiring the `-e' option. +This sets the default value of the xpg_echo shell option to on, +which makes the Bash echo behave more like the version specified in +the Single Unix Specification, version 3. +See section 4.2 Bash Builtin Commands, for a description of the escape sequences that +echo recognizes. +

+ +

+

+ +The file `config-top.h' contains C Preprocessor +`#define' statements for options which are not settable from +configure. +Some of these are not meant to be changed; beware of the consequences if +you do. +Read the comments associated with each definition for more +information about its effect. +

+ + +

+ + + + + + + + + + + +
[ < ][ > ]   [ << ][ Up ][ >> ]         [Top][Contents][Index][ ? ]
+

A. Reporting Bugs

+ +

+ +Please report all bugs you find in Bash. +But first, you should +make sure that it really is a bug, and that it appears in the latest +version of Bash. +The latest version of Bash is always available for FTP from +ftp://ftp.gnu.org/pub/bash/. +

+ +Once you have determined that a bug actually exists, use the +bashbug command to submit a bug report. +If you have a fix, you are encouraged to mail that as well! +Suggestions and `philosophical' bug reports may be mailed +to bug-bash@gnu.org or posted to the Usenet +newsgroup gnu.bash.bug. +

+ +All bug reports should include: +

    +
  • +The version number of Bash. +
  • +The hardware and operating system. +
  • +The compiler used to compile Bash. +
  • +A description of the bug behaviour. +
  • +A short script or `recipe' which exercises the bug and may be used +to reproduce it. +
+

+ +bashbug inserts the first three items automatically into +the template it provides for filing a bug report. +

+ +Please send all reports concerning this manual to +chet@po.CWRU.Edu. +

+ + +

+ + + + + + + + + + + +
[ < ][ > ]   [ << ][ Up ][ >> ]         [Top][Contents][Index][ ? ]
+

B. Major Differences From The Bourne Shell

+ +

+ +Bash implements essentially the same grammar, parameter and +variable expansion, redirection, and quoting as the Bourne Shell. +Bash uses the POSIX standard as the specification of +how these features are to be implemented. There are some +differences between the traditional Bourne shell and Bash; this +section quickly details the differences of significance. A +number of these differences are explained in greater depth in +previous sections. +This section uses the version of sh included in SVR4.2 (the +last version of the historical Bourne shell) as the baseline reference. +

+ +

    + +
  • +Bash is POSIX-conformant, even where the POSIX specification +differs from traditional sh behavior (see section 6.11 Bash POSIX Mode). +

    + +

  • +Bash has multi-character invocation options (see section 6.1 Invoking Bash). +

    + +

  • +Bash has command-line editing (see section 8. Command Line Editing) and +the bind builtin. +

    + +

  • +Bash provides a programmable word completion mechanism +(see section 8.6 Programmable Completion), and two builtin commands, +complete and compgen, to manipulate it. +

    + +

  • +Bash has command history (see section 9.1 Bash History Facilities) and the +history and fc builtins to manipulate it. +The Bash history list maintains timestamp information and uses the +value of the HISTTIMEFORMAT variable to display it. +

    + +

  • +Bash implements csh-like history expansion +(see section 9.3 History Expansion). +

    + +

  • +Bash has one-dimensional array variables (see section 6.7 Arrays), and the +appropriate variable expansions and assignment syntax to use them. +Several of the Bash builtins take options to act on arrays. +Bash provides a number of built-in array variables. +

    + +

  • +The $'...' quoting syntax, which expands ANSI-C +backslash-escaped characters in the text between the single quotes, +is supported (see section 3.1.2.4 ANSI-C Quoting). +

    + +

  • +Bash supports the $"..." quoting syntax to do +locale-specific translation of the characters between the double +quotes. The `-D', `--dump-strings', and `--dump-po-strings' +invocation options list the translatable strings found in a script +(see section 3.1.2.5 Locale-Specific Translation). +

    + +

  • +Bash implements the ! keyword to negate the return value of +a pipeline (see section 3.2.2 Pipelines). +Very useful when an if statement needs to act only if a test fails. +The Bash `-o pipefail' option to set will cause a pipeline to +return a failure status if any command fails. +

    + +

  • +Bash has the time reserved word and command timing (see section 3.2.2 Pipelines). +The display of the timing statistics may be controlled with the +TIMEFORMAT variable. +

    + +

  • +Bash implements the for (( expr1 ; expr2 ; expr3 )) +arithmetic for command, similar to the C language (see section 3.2.4.1 Looping Constructs). +

    + +

  • +Bash includes the select compound command, which allows the +generation of simple menus (see section 3.2.4.2 Conditional Constructs). +

    + +

  • +Bash includes the [[ compound command, which makes conditional +testing part of the shell grammar (see section 3.2.4.2 Conditional Constructs), including +optional regular expression matching. +

    + +

  • +Bash provides optional case-insensitive matching for the case and +[[ constructs. +

    + +

  • +Bash includes brace expansion (see section 3.5.1 Brace Expansion) and tilde +expansion (see section 3.5.2 Tilde Expansion). +

    + +

  • +Bash implements command aliases and the alias and unalias +builtins (see section 6.6 Aliases). +

    + +

  • +Bash provides shell arithmetic, the (( compound command +(see section 3.2.4.2 Conditional Constructs), +and arithmetic expansion (see section 6.5 Shell Arithmetic). +

    + +

  • +Variables present in the shell's initial environment are automatically +exported to child processes. The Bourne shell does not normally do +this unless the variables are explicitly marked using the export +command. +

    + +

  • +Bash supports the `+=' assignment operator, which appends to the value +of the variable named on the left hand side. +

    + +

  • +Bash includes the POSIX pattern removal `%', `#', `%%' +and `##' expansions to remove leading or trailing substrings from +variable values (see section 3.5.3 Shell Parameter Expansion). +

    + +

  • +The expansion ${#xx}, which returns the length of ${xx}, +is supported (see section 3.5.3 Shell Parameter Expansion). +

    + +

  • +The expansion ${var:offset[:length]}, +which expands to the substring of var's value of length +length, beginning at offset, is present +(see section 3.5.3 Shell Parameter Expansion). +

    + +

  • +The expansion +${var/[/]pattern[/replacement]}, +which matches pattern and replaces it with replacement in +the value of var, is available (see section 3.5.3 Shell Parameter Expansion). +

    + +

  • +The expansion ${!prefix}* expansion, which expands to +the names of all shell variables whose names begin with prefix, +is available (see section 3.5.3 Shell Parameter Expansion). +

    + +

  • +Bash has indirect variable expansion using ${!word} +(see section 3.5.3 Shell Parameter Expansion). +

    + +

  • +Bash can expand positional parameters beyond $9 using +${num}. +

    + +

  • +The POSIX $() form of command substitution +is implemented (see section 3.5.4 Command Substitution), +and preferred to the Bourne shell's " (which +is also implemented for backwards compatibility). +

    + +

  • +Bash has process substitution (see section 3.5.6 Process Substitution). +

    + +

  • +Bash automatically assigns variables that provide information about the +current user (UID, EUID, and GROUPS), the current host +(HOSTTYPE, OSTYPE, MACHTYPE, and HOSTNAME), +and the instance of Bash that is running (BASH, +BASH_VERSION, and BASH_VERSINFO). See section 5.2 Bash Variables, +for details. +

    + +

  • +The IFS variable is used to split only the results of expansion, +not all words (see section 3.5.7 Word Splitting). +This closes a longstanding shell security hole. +

    + +

  • +Bash implements the full set of POSIX filename expansion operators, +including character classes, equivalence classes, and +collating symbols (see section 3.5.8 Filename Expansion). +

    + +

  • +Bash implements extended pattern matching features when the extglob +shell option is enabled (see section 3.5.8.1 Pattern Matching). +

    + +

  • +It is possible to have a variable and a function with the same name; +sh does not separate the two name spaces. +

    + +

  • +Bash functions are permitted to have local variables using the +local builtin, and thus useful recursive functions may be written +(see section 4.2 Bash Builtin Commands). +

    + +

  • +Variable assignments preceding commands affect only that command, even +builtins and functions (see section 3.7.4 Environment). +In sh, all variable assignments +preceding commands are global unless the command is executed from the +file system. +

    + +

  • +Bash performs filename expansion on filenames specified as operands +to input and output redirection operators (see section 3.6 Redirections). +

    + +

  • +Bash contains the `<>' redirection operator, allowing a file to be +opened for both reading and writing, and the `&>' redirection +operator, for directing standard output and standard error to the same +file (see section 3.6 Redirections). +

    + +

  • +Bash includes the `<<<' redirection operator, allowing a string to +be used as the standard input to a command. +

    + +

  • +Bash implements the `[n]<&word' and `[n]>&word' +redirection operators, which move one file descriptor to another. +

    + +

  • +Bash treats a number of filenames specially when they are +used in redirection operators (see section 3.6 Redirections). +

    + +

  • +Bash can open network connections to arbitrary machines and services +with the redirection operators (see section 3.6 Redirections). +

    + +

  • +The noclobber option is available to avoid overwriting existing +files with output redirection (see section 4.3.1 The Set Builtin). +The `>|' redirection operator may be used to override noclobber. +

    + +

  • +The Bash cd and pwd builtins (see section 4.1 Bourne Shell Builtins) +each take `-L' and `-P' options to switch between logical and +physical modes. +

    + +

  • +Bash allows a function to override a builtin with the same name, and provides +access to that builtin's functionality within the function via the +builtin and command builtins (see section 4.2 Bash Builtin Commands). +

    + +

  • +The command builtin allows selective disabling of functions +when command lookup is performed (see section 4.2 Bash Builtin Commands). +

    + +

  • +Individual builtins may be enabled or disabled using the enable +builtin (see section 4.2 Bash Builtin Commands). +

    + +

  • +The Bash exec builtin takes additional options that allow users +to control the contents of the environment passed to the executed +command, and what the zeroth argument to the command is to be +(see section 4.1 Bourne Shell Builtins). +

    + +

  • +Shell functions may be exported to children via the environment +using export -f (see section 3.3 Shell Functions). +

    + +

  • +The Bash export, readonly, and declare builtins can +take a `-f' option to act on shell functions, a `-p' option to +display variables with various attributes set in a format that can be +used as shell input, a `-n' option to remove various variable +attributes, and `name=value' arguments to set variable attributes +and values simultaneously. +

    + +

  • +The Bash hash builtin allows a name to be associated with +an arbitrary filename, even when that filename cannot be found by +searching the $PATH, using `hash -p' +(see section 4.1 Bourne Shell Builtins). +

    + +

  • +Bash includes a help builtin for quick reference to shell +facilities (see section 4.2 Bash Builtin Commands). +

    + +

  • +The printf builtin is available to display formatted output +(see section 4.2 Bash Builtin Commands). +

    + +

  • +The Bash read builtin (see section 4.2 Bash Builtin Commands) +will read a line ending in `\' with +the `-r' option, and will use the REPLY variable as a +default if no non-option arguments are supplied. +The Bash read builtin +also accepts a prompt string with the `-p' option and will use +Readline to obtain the line when given the `-e' option. +The read builtin also has additional options to control input: +the `-s' option will turn off echoing of input characters as +they are read, the `-t' option will allow read to time out +if input does not arrive within a specified number of seconds, the +`-n' option will allow reading only a specified number of +characters rather than a full line, and the `-d' option will read +until a particular character rather than newline. +

    + +

  • +The return builtin may be used to abort execution of scripts +executed with the . or source builtins +(see section 4.1 Bourne Shell Builtins). +

    + +

  • +Bash includes the shopt builtin, for finer control of shell +optional capabilities (see section 4.3.2 The Shopt Builtin), and allows these options +to be set and unset at shell invocation (see section 6.1 Invoking Bash). +

    + +

  • +Bash has much more optional behavior controllable with the set +builtin (see section 4.3.1 The Set Builtin). +

    + +

  • +The `-x' (xtrace) option displays commands other than +simple commands when performing an execution trace +(see section 4.3.1 The Set Builtin). +

    + +

  • +The test builtin (see section 4.1 Bourne Shell Builtins) +is slightly different, as it implements the POSIX algorithm, +which specifies the behavior based on the number of arguments. +

    + +

  • +Bash includes the caller builtin, which displays the context of +any active subroutine call (a shell function or a script executed with +the . or source builtins). This supports the bash +debugger. +

    + +

  • +The trap builtin (see section 4.1 Bourne Shell Builtins) allows a +DEBUG pseudo-signal specification, similar to EXIT. +Commands specified with a DEBUG trap are executed before every +simple command, for command, case command, +select command, every arithmetic for command, and before +the first command executes in a shell function. +The DEBUG trap is not inherited by shell functions unless the +function has been given the trace attribute or the +functrace option has been enabled using the shopt builtin. +The extdebug shell option has additional effects on the +DEBUG trap. +

    + +The trap builtin (see section 4.1 Bourne Shell Builtins) allows an +ERR pseudo-signal specification, similar to EXIT and DEBUG. +Commands specified with an ERR trap are executed after a simple +command fails, with a few exceptions. +The ERR trap is not inherited by shell functions unless the +-o errtrace option to the set builtin is enabled. +

    + +The trap builtin (see section 4.1 Bourne Shell Builtins) allows a +RETURN pseudo-signal specification, similar to +EXIT and DEBUG. +Commands specified with an RETURN trap are executed before +execution resumes after a shell function or a shell script executed with +. or source returns. +The RETURN trap is not inherited by shell functions unless the +function has been given the trace attribute or the +functrace option has been enabled using the shopt builtin. +

    + +

  • +The Bash type builtin is more extensive and gives more information +about the names it finds (see section 4.2 Bash Builtin Commands). +

    + +

  • +The Bash umask builtin permits a `-p' option to cause +the output to be displayed in the form of a umask command +that may be reused as input (see section 4.1 Bourne Shell Builtins). +

    + +

  • +Bash implements a csh-like directory stack, and provides the +pushd, popd, and dirs builtins to manipulate it +(see section 6.8 The Directory Stack). +Bash also makes the directory stack visible as the value of the +DIRSTACK shell variable. +

    + +

  • +Bash interprets special backslash-escaped characters in the prompt +strings when interactive (see section 6.9 Controlling the Prompt). +

    + +

  • +The Bash restricted mode is more useful (see section 6.10 The Restricted Shell); +the SVR4.2 shell restricted mode is too limited. +

    + +

  • +The disown builtin can remove a job from the internal shell +job table (see section 7.2 Job Control Builtins) or suppress the sending +of SIGHUP to a job when the shell exits as the result of a +SIGHUP. +

    + +

  • +Bash includes a number of features to support a separate debugger for +shell scripts. +

    + +

  • +The SVR4.2 shell has two privilege-related builtins +(mldmode and priv) not present in Bash. +

    + +

  • +Bash does not have the stop or newgrp builtins. +

    + +

  • +Bash does not use the SHACCT variable or perform shell accounting. +

    + +

  • +The SVR4.2 sh uses a TIMEOUT variable like Bash uses +TMOUT. +

    + +

+

+ +More features unique to Bash may be found in 6. Bash Features. +

+ +

+ + + + + + + + + + + +
[ < ][ > ]   [ << ][ Up ][ >> ]         [Top][Contents][Index][ ? ]
+

B.1 Implementation Differences From The SVR4.2 Shell

+ +

+ +Since Bash is a completely new implementation, it does not suffer from +many of the limitations of the SVR4.2 shell. For instance: +

+ +

    + +
  • +Bash does not fork a subshell when redirecting into or out of +a shell control structure such as an if or while +statement. +

    + +

  • +Bash does not allow unbalanced quotes. The SVR4.2 shell will silently +insert a needed closing quote at EOF under certain circumstances. +This can be the cause of some hard-to-find errors. +

    + +

  • +The SVR4.2 shell uses a baroque memory management scheme based on +trapping SIGSEGV. If the shell is started from a process with +SIGSEGV blocked (e.g., by using the system() C library +function call), it misbehaves badly. +

    + +

  • +In a questionable attempt at security, the SVR4.2 shell, +when invoked without the `-p' option, will alter its real +and effective UID and GID if they are less than some +magic threshold value, commonly 100. +This can lead to unexpected results. +

    + +

  • +The SVR4.2 shell does not allow users to trap SIGSEGV, +SIGALRM, or SIGCHLD. +

    + +

  • +The SVR4.2 shell does not allow the IFS, MAILCHECK, +PATH, PS1, or PS2 variables to be unset. +

    + +

  • +The SVR4.2 shell treats `^' as the undocumented equivalent of +`|'. +

    + +

  • +Bash allows multiple option arguments when it is invoked (-x -v); +the SVR4.2 shell allows only one option argument (-xv). In +fact, some versions of the shell dump core if the second argument begins +with a `-'. +

    + +

  • +The SVR4.2 shell exits a script if any builtin fails; Bash exits +a script only if one of the POSIX special builtins fails, and +only for certain failures, as enumerated in the POSIX standard. +

    + +

  • +The SVR4.2 shell behaves differently when invoked as jsh +(it turns on job control). +
+

+ + +

+ + + + + + + + + + + +
[ < ][ > ]   [ << ][ Up ][ >> ]         [Top][Contents][Index][ ? ]
+

C. Copying This Manual

+ +

+ +

+ +
C.1 GNU Free Documentation License  License for copying this manual.
+

+ + +

+ + + + + + + + + + + +
[ < ][ > ]   [ << ][ Up ][ >> ]         [Top][Contents][Index][ ? ]
+

C.1 GNU Free Documentation License

+ +

+ + +

+ Version 1.2, November 2002 +
+

+ +
 
Copyright (C) 2000,2001,2002 Free Software Foundation, Inc.
+59 Temple Place, Suite 330, Boston, MA  02111-1307, USA
+
+Everyone is permitted to copy and distribute verbatim copies
+of this license document, but changing it is not allowed.
+

+ +

    +
  1. +PREAMBLE +

    + +The purpose of this License is to make a manual, textbook, or other +functional and useful document free in the sense of freedom: to +assure everyone the effective freedom to copy and redistribute it, +with or without modifying it, either commercially or noncommercially. +Secondarily, this License preserves for the author and publisher a way +to get credit for their work, while not being considered responsible +for modifications made by others. +

    + +This License is a kind of "copyleft", which means that derivative +works of the document must themselves be free in the same sense. It +complements the GNU General Public License, which is a copyleft +license designed for free software. +

    + +We have designed this License in order to use it for manuals for free +software, because free software needs free documentation: a free +program should come with manuals providing the same freedoms that the +software does. But this License is not limited to software manuals; +it can be used for any textual work, regardless of subject matter or +whether it is published as a printed book. We recommend this License +principally for works whose purpose is instruction or reference. +

    + +

  2. +APPLICABILITY AND DEFINITIONS +

    + +This License applies to any manual or other work, in any medium, that +contains a notice placed by the copyright holder saying it can be +distributed under the terms of this License. Such a notice grants a +world-wide, royalty-free license, unlimited in duration, to use that +work under the conditions stated herein. The "Document", below, +refers to any such manual or work. Any member of the public is a +licensee, and is addressed as "you". You accept the license if you +copy, modify or distribute the work in a way requiring permission +under copyright law. +

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    + +The "Title Page" means, for a printed book, the title page itself, +plus such following pages as are needed to hold, legibly, the material +this License requires to appear in the title page. For works in +formats which do not have any title page as such, "Title Page" means +the text near the most prominent appearance of the work's title, +preceding the beginning of the body of the text. +

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    + +The Document may include Warranty Disclaimers next to the notice which +states that this License applies to the Document. These Warranty +Disclaimers are considered to be included by reference in this +License, but only as regards disclaiming warranties: any other +implication that these Warranty Disclaimers may have is void and has +no effect on the meaning of this License. +

    + +

  3. +VERBATIM COPYING +

    + +You may copy and distribute the Document in any medium, either +commercially or noncommercially, provided that this License, the +copyright notices, and the license notice saying this License applies +to the Document are reproduced in all copies, and that you add no other +conditions whatsoever to those of this License. You may not use +technical measures to obstruct or control the reading or further +copying of the copies you make or distribute. However, you may accept +compensation in exchange for copies. If you distribute a large enough +number of copies you must also follow the conditions in section 3. +

    + +You may also lend copies, under the same conditions stated above, and +you may publicly display copies. +

    + +

  4. +COPYING IN QUANTITY +

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    + +If the required texts for either cover are too voluminous to fit +legibly, you should put the first ones listed (as many as fit +reasonably) on the actual cover, and continue the rest onto adjacent +pages. +

    + +If you publish or distribute Opaque copies of the Document numbering +more than 100, you must either include a machine-readable Transparent +copy along with each Opaque copy, or state in or with each Opaque copy +a computer-network location from which the general network-using +public has access to download using public-standard network protocols +a complete Transparent copy of the Document, free of added material. +If you use the latter option, you must take reasonably prudent steps, +when you begin distribution of Opaque copies in quantity, to ensure +that this Transparent copy will remain thus accessible at the stated +location until at least one year after the last time you distribute an +Opaque copy (directly or through your agents or retailers) of that +edition to the public. +

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    + +

  5. +MODIFICATIONS +

    + +You may copy and distribute a Modified Version of the Document under +the conditions of sections 2 and 3 above, provided that you release +the Modified Version under precisely this License, with the Modified +Version filling the role of the Document, thus licensing distribution +and modification of the Modified Version to whoever possesses a copy +of it. In addition, you must do these things in the Modified Version: +

    + +

      +
    1. +Use in the Title Page (and on the covers, if any) a title distinct +from that of the Document, and from those of previous versions +(which should, if there were any, be listed in the History section +of the Document). You may use the same title as a previous version +if the original publisher of that version gives permission. +

      + +

    2. +List on the Title Page, as authors, one or more persons or entities +responsible for authorship of the modifications in the Modified +Version, together with at least five of the principal authors of the +Document (all of its principal authors, if it has fewer than five), +unless they release you from this requirement. +

      + +

    3. +State on the Title page the name of the publisher of the +Modified Version, as the publisher. +

      + +

    4. +Preserve all the copyright notices of the Document. +

      + +

    5. +Add an appropriate copyright notice for your modifications +adjacent to the other copyright notices. +

      + +

    6. +Include, immediately after the copyright notices, a license notice +giving the public permission to use the Modified Version under the +terms of this License, in the form shown in the Addendum below. +

      + +

    7. +Preserve in that license notice the full lists of Invariant Sections +and required Cover Texts given in the Document's license notice. +

      + +

    8. +Include an unaltered copy of this License. +

      + +

    9. +Preserve the section Entitled "History", Preserve its Title, and add +to it an item stating at least the title, year, new authors, and +publisher of the Modified Version as given on the Title Page. If +there is no section Entitled "History" in the Document, create one +stating the title, year, authors, and publisher of the Document as +given on its Title Page, then add an item describing the Modified +Version as stated in the previous sentence. +

      + +

    10. +Preserve the network location, if any, given in the Document for +public access to a Transparent copy of the Document, and likewise +the network locations given in the Document for previous versions +it was based on. These may be placed in the "History" section. +You may omit a network location for a work that was published at +least four years before the Document itself, or if the original +publisher of the version it refers to gives permission. +

      + +

    11. +For any section Entitled "Acknowledgements" or "Dedications", Preserve +the Title of the section, and preserve in the section all the +substance and tone of each of the contributor acknowledgements and/or +dedications given therein. +

      + +

    12. +Preserve all the Invariant Sections of the Document, +unaltered in their text and in their titles. Section numbers +or the equivalent are not considered part of the section titles. +

      + +

    13. +Delete any section Entitled "Endorsements". Such a section +may not be included in the Modified Version. +

      + +

    14. +Do not retitle any existing section to be Entitled "Endorsements" or +to conflict in title with any Invariant Section. +

      + +

    15. +Preserve any Warranty Disclaimers. +
    +

    + +If the Modified Version includes new front-matter sections or +appendices that qualify as Secondary Sections and contain no material +copied from the Document, you may at your option designate some or all +of these sections as invariant. To do this, add their titles to the +list of Invariant Sections in the Modified Version's license notice. +These titles must be distinct from any other section titles. +

    + +You may add a section Entitled "Endorsements", provided it contains +nothing but endorsements of your Modified Version by various +parties--for example, statements of peer review or that the text has +been approved by an organization as the authoritative definition of a +standard. +

    + +You may add a passage of up to five words as a Front-Cover Text, and a +passage of up to 25 words as a Back-Cover Text, to the end of the list +of Cover Texts in the Modified Version. Only one passage of +Front-Cover Text and one of Back-Cover Text may be added by (or +through arrangements made by) any one entity. If the Document already +includes a cover text for the same cover, previously added by you or +by arrangement made by the same entity you are acting on behalf of, +you may not add another; but you may replace the old one, on explicit +permission from the previous publisher that added the old one. +

    + +The author(s) and publisher(s) of the Document do not by this License +give permission to use their names for publicity for or to assert or +imply endorsement of any Modified Version. +

    + +

  6. +COMBINING DOCUMENTS +

    + +You may combine the Document with other documents released under this +License, under the terms defined in section 4 above for modified +versions, provided that you include in the combination all of the +Invariant Sections of all of the original documents, unmodified, and +list them all as Invariant Sections of your combined work in its +license notice, and that you preserve all their Warranty Disclaimers. +

    + +The combined work need only contain one copy of this License, and +multiple identical Invariant Sections may be replaced with a single +copy. If there are multiple Invariant Sections with the same name but +different contents, make the title of each such section unique by +adding at the end of it, in parentheses, the name of the original +author or publisher of that section if known, or else a unique number. +Make the same adjustment to the section titles in the list of +Invariant Sections in the license notice of the combined work. +

    + +In the combination, you must combine any sections Entitled "History" +in the various original documents, forming one section Entitled +"History"; likewise combine any sections Entitled "Acknowledgements", +and any sections Entitled "Dedications". You must delete all +sections Entitled "Endorsements." +

    + +

  7. +COLLECTIONS OF DOCUMENTS +

    + +You may make a collection consisting of the Document and other documents +released under this License, and replace the individual copies of this +License in the various documents with a single copy that is included in +the collection, provided that you follow the rules of this License for +verbatim copying of each of the documents in all other respects. +

    + +You may extract a single document from such a collection, and distribute +it individually under this License, provided you insert a copy of this +License into the extracted document, and follow this License in all +other respects regarding verbatim copying of that document. +

    + +

  8. +AGGREGATION WITH INDEPENDENT WORKS +

    + +A compilation of the Document or its derivatives with other separate +and independent documents or works, in or on a volume of a storage or +distribution medium, is called an "aggregate" if the copyright +resulting from the compilation is not used to limit the legal rights +of the compilation's users beyond what the individual works permit. +When the Document is included an aggregate, this License does not +apply to the other works in the aggregate which are not themselves +derivative works of the Document. +

    + +If the Cover Text requirement of section 3 is applicable to these +copies of the Document, then if the Document is less than one half of +the entire aggregate, the Document's Cover Texts may be placed on +covers that bracket the Document within the aggregate, or the +electronic equivalent of covers if the Document is in electronic form. +Otherwise they must appear on printed covers that bracket the whole +aggregate. +

    + +

  9. +TRANSLATION +

    + +Translation is considered a kind of modification, so you may +distribute translations of the Document under the terms of section 4. +Replacing Invariant Sections with translations requires special +permission from their copyright holders, but you may include +translations of some or all Invariant Sections in addition to the +original versions of these Invariant Sections. You may include a +translation of this License, and all the license notices in the +Document, and any Warranty Disclaimers, provided that you also include +the original English version of this License and the original versions +of those notices and disclaimers. In case of a disagreement between +the translation and the original version of this License or a notice +or disclaimer, the original version will prevail. +

    + +If a section in the Document is Entitled "Acknowledgements", +"Dedications", or "History", the requirement (section 4) to Preserve +its Title (section 1) will typically require changing the actual +title. +

    + +

  10. +TERMINATION +

    + +You may not copy, modify, sublicense, or distribute the Document except +as expressly provided for under this License. Any other attempt to +copy, modify, sublicense or distribute the Document is void, and will +automatically terminate your rights under this License. However, +parties who have received copies, or rights, from you under this +License will not have their licenses terminated so long as such +parties remain in full compliance. +

    + +

  11. +FUTURE REVISIONS OF THIS LICENSE +

    + +The Free Software Foundation may publish new, revised versions +of the GNU Free Documentation License from time to time. Such new +versions will be similar in spirit to the present version, but may +differ in detail to address new problems or concerns. See +http://www.gnu.org/copyleft/. +

    + +Each version of the License is given a distinguishing version number. +If the Document specifies that a particular numbered version of this +License "or any later version" applies to it, you have the option of +following the terms and conditions either of that specified version or +of any later version that has been published (not as a draft) by the +Free Software Foundation. If the Document does not specify a version +number of this License, you may choose any version ever published (not +as a draft) by the Free Software Foundation. +

+

+ +

+ + + + + + + + + + + +
[ < ][ > ]   [ << ][ Up ][ >> ]         [Top][Contents][Index][ ? ]
+

C.1.1 ADDENDUM: How to use this License for your documents

+ +

+ +To use this License in a document you have written, include a copy of +the License in the document and put the following copyright and +license notices just after the title page: +

+ +
 
  Copyright (C)  year  your name.
+  Permission is granted to copy, distribute and/or modify this document
+  under the terms of the GNU Free Documentation License, Version 1.2
+  or any later version published by the Free Software Foundation;
+  with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
+  A copy of the license is included in the section entitled ``GNU
+  Free Documentation License''.
+

+ +If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, +replace the "with...Texts." line with this: +

+ +
 
    with the Invariant Sections being list their titles, with
+    the Front-Cover Texts being list, and with the Back-Cover Texts
+    being list.
+

+ +If you have Invariant Sections without Cover Texts, or some other +combination of the three, merge those two alternatives to suit the +situation. +

+ +If your document contains nontrivial examples of program code, we +recommend releasing these examples in parallel under your choice of +free software license, such as the GNU General Public License, +to permit their use in free software. +

+ + +

+ + + + + + + + + + + +
[ < ][ > ]   [ << ][ Up ][ >> ]         [Top][Contents][Index][ ? ]
+

D. Indexes

+ +

+ +

+ + + + + +
D.1 Index of Shell Builtin Commands  Index of Bash builtin commands.
D.2 Index of Shell Reserved Words  Index of Bash reserved words.
D.3 Parameter and Variable Index  Quick reference helps you find the + variable you want.
D.4 Function Index  Index of bindable Readline functions.
D.5 Concept Index  General index for concepts described in + this manual.
+

+ + +

+ + + + + + + + + + + +
[ < ][ > ]   [ << ][ Up ][ >> ]         [Top][Contents][Index][ ? ]
+

D.1 Index of Shell Builtin Commands

+ +
Jump to:   . +   +: +   +[ +   +
+A +   +B +   +C +   +D +   +E +   +F +   +G +   +H +   +J +   +K +   +L +   +P +   +R +   +S +   +T +   +U +   +W +   +

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
Index Entry Section
.
.4.1 Bourne Shell Builtins
:
:4.1 Bourne Shell Builtins
[
[4.1 Bourne Shell Builtins
A
alias4.2 Bash Builtin Commands
B
bg7.2 Job Control Builtins
bind4.2 Bash Builtin Commands
break4.1 Bourne Shell Builtins
builtin4.2 Bash Builtin Commands
C
caller4.2 Bash Builtin Commands
cd4.1 Bourne Shell Builtins
command4.2 Bash Builtin Commands
compgen8.7 Programmable Completion Builtins
complete8.7 Programmable Completion Builtins
continue4.1 Bourne Shell Builtins
D
declare4.2 Bash Builtin Commands
dirs6.8.1 Directory Stack Builtins
disown7.2 Job Control Builtins
E
echo4.2 Bash Builtin Commands
enable4.2 Bash Builtin Commands
eval4.1 Bourne Shell Builtins
exec4.1 Bourne Shell Builtins
exit4.1 Bourne Shell Builtins
export4.1 Bourne Shell Builtins
F
fc9.2 Bash History Builtins
fg7.2 Job Control Builtins
G
getopts4.1 Bourne Shell Builtins
H
hash4.1 Bourne Shell Builtins
help4.2 Bash Builtin Commands
history9.2 Bash History Builtins
J
jobs7.2 Job Control Builtins
K
kill7.2 Job Control Builtins
L
let4.2 Bash Builtin Commands
local4.2 Bash Builtin Commands
logout4.2 Bash Builtin Commands
P
popd6.8.1 Directory Stack Builtins
printf4.2 Bash Builtin Commands
pushd6.8.1 Directory Stack Builtins
pwd4.1 Bourne Shell Builtins
R
read4.2 Bash Builtin Commands
readonly4.1 Bourne Shell Builtins
return4.1 Bourne Shell Builtins
S
set4.3.1 The Set Builtin
shift4.1 Bourne Shell Builtins
shopt4.3.2 The Shopt Builtin
source4.2 Bash Builtin Commands
suspend7.2 Job Control Builtins
T
test4.1 Bourne Shell Builtins
times4.1 Bourne Shell Builtins
trap4.1 Bourne Shell Builtins
type4.2 Bash Builtin Commands
typeset4.2 Bash Builtin Commands
U
ulimit4.2 Bash Builtin Commands
umask4.1 Bourne Shell Builtins
unalias4.2 Bash Builtin Commands
unset4.1 Bourne Shell Builtins
W
wait7.2 Job Control Builtins

Jump to:   . +   +: +   +[ +   +
+A +   +B +   +C +   +D +   +E +   +F +   +G +   +H +   +J +   +K +   +L +   +P +   +R +   +S +   +T +   +U +   +W +   +

+ + +

+ + + + + + + + + + + +
[ < ][ > ]   [ << ][ Up ][ >> ]         [Top][Contents][Index][ ? ]
+

D.2 Index of Shell Reserved Words

+ +
Jump to:   ! +   +[ +   +] +   +{ +   +} +   +
+C +   +D +   +E +   +F +   +I +   +S +   +T +   +U +   +W +   +

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
Index Entry Section
!
!3.2.2 Pipelines
[
[[3.2.4.2 Conditional Constructs
]
]]3.2.4.2 Conditional Constructs
{
{3.2.4.3 Grouping Commands
}
}3.2.4.3 Grouping Commands
C
case3.2.4.2 Conditional Constructs
D
do3.2.4.1 Looping Constructs
done3.2.4.1 Looping Constructs
E
elif3.2.4.2 Conditional Constructs
else3.2.4.2 Conditional Constructs
esac3.2.4.2 Conditional Constructs
F
fi3.2.4.2 Conditional Constructs
for3.2.4.1 Looping Constructs
function3.3 Shell Functions
I
if3.2.4.2 Conditional Constructs
in3.2.4.2 Conditional Constructs
S
select3.2.4.2 Conditional Constructs
T
then3.2.4.2 Conditional Constructs
time3.2.2 Pipelines
U
until3.2.4.1 Looping Constructs
W
while3.2.4.1 Looping Constructs

Jump to:   ! +   +[ +   +] +   +{ +   +} +   +
+C +   +D +   +E +   +F +   +I +   +S +   +T +   +U +   +W +   +

+ + +

+ + + + + + + + + + + +
[ < ][ > ]   [ << ][ Up ][ >> ]         [Top][Contents][Index][ ? ]
+

D.3 Parameter and Variable Index

+ +
Jump to:   ! +   +# +   +$ +   +* +   +- +   +0 +   +? +   +@ +   +_ +   +
+A +   +B +   +C +   +D +   +E +   +F +   +G +   +H +   +I +   +K +   +L +   +M +   +O +   +P +   +R +   +S +   +T +   +U +   +V +   +

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
Index Entry Section
!
!3.4.2 Special Parameters
!3.4.2 Special Parameters
#
#3.4.2 Special Parameters
#3.4.2 Special Parameters
$
$3.4.2 Special Parameters
$3.4.2 Special Parameters
*
*3.4.2 Special Parameters
*3.4.2 Special Parameters
-
-3.4.2 Special Parameters
-3.4.2 Special Parameters
0
03.4.2 Special Parameters
03.4.2 Special Parameters
?
?3.4.2 Special Parameters
?3.4.2 Special Parameters
@
@3.4.2 Special Parameters
@3.4.2 Special Parameters
_
_3.4.2 Special Parameters
_3.4.2 Special Parameters
A
auto_resume7.3 Job Control Variables
auto_resume7.3 Job Control Variables
B
BASH5.2 Bash Variables
BASH5.2 Bash Variables
BASH_ARGC5.2 Bash Variables
BASH_ARGC5.2 Bash Variables
BASH_ARGV5.2 Bash Variables
BASH_ARGV5.2 Bash Variables
BASH_COMMAND5.2 Bash Variables
BASH_COMMAND5.2 Bash Variables
BASH_ENV5.2 Bash Variables
BASH_ENV5.2 Bash Variables
BASH_EXECUTION_STRING5.2 Bash Variables
BASH_EXECUTION_STRING5.2 Bash Variables
BASH_LINENO5.2 Bash Variables
BASH_LINENO5.2 Bash Variables
BASH_REMATCH5.2 Bash Variables
BASH_REMATCH5.2 Bash Variables
BASH_SOURCE5.2 Bash Variables
BASH_SOURCE5.2 Bash Variables
BASH_SUBSHELL5.2 Bash Variables
BASH_SUBSHELL5.2 Bash Variables
BASH_VERSINFO5.2 Bash Variables
BASH_VERSINFO5.2 Bash Variables
BASH_VERSION5.2 Bash Variables
BASH_VERSION5.2 Bash Variables
BASHPID5.2 Bash Variables
BASHPID5.2 Bash Variables
bell-style8.3.1 Readline Init File Syntax
bind-tty-special-chars8.3.1 Readline Init File Syntax
C
CDPATH5.1 Bourne Shell Variables
CDPATH5.1 Bourne Shell Variables
COLUMNS5.2 Bash Variables
COLUMNS5.2 Bash Variables
comment-begin8.3.1 Readline Init File Syntax
COMP_CWORD5.2 Bash Variables
COMP_CWORD5.2 Bash Variables
COMP_KEY5.2 Bash Variables
COMP_KEY5.2 Bash Variables
COMP_LINE5.2 Bash Variables
COMP_LINE5.2 Bash Variables
COMP_POINT5.2 Bash Variables
COMP_POINT5.2 Bash Variables
COMP_TYPE5.2 Bash Variables
COMP_TYPE5.2 Bash Variables
COMP_WORDBREAKS5.2 Bash Variables
COMP_WORDBREAKS5.2 Bash Variables
COMP_WORDS5.2 Bash Variables
COMP_WORDS5.2 Bash Variables
completion-query-items8.3.1 Readline Init File Syntax
COMPREPLY5.2 Bash Variables
COMPREPLY5.2 Bash Variables
convert-meta8.3.1 Readline Init File Syntax
D
DIRSTACK5.2 Bash Variables
DIRSTACK5.2 Bash Variables
disable-completion8.3.1 Readline Init File Syntax
E
editing-mode8.3.1 Readline Init File Syntax
EMACS5.2 Bash Variables
EMACS5.2 Bash Variables
enable-keypad8.3.1 Readline Init File Syntax
EUID5.2 Bash Variables
EUID5.2 Bash Variables
expand-tilde8.3.1 Readline Init File Syntax
F
FCEDIT5.2 Bash Variables
FCEDIT5.2 Bash Variables
FIGNORE5.2 Bash Variables
FIGNORE5.2 Bash Variables
FUNCNAME5.2 Bash Variables
FUNCNAME5.2 Bash Variables
G
GLOBIGNORE5.2 Bash Variables
GLOBIGNORE5.2 Bash Variables
GROUPS5.2 Bash Variables
GROUPS5.2 Bash Variables
H
histchars5.2 Bash Variables
histchars5.2 Bash Variables
HISTCMD5.2 Bash Variables
HISTCMD5.2 Bash Variables
HISTCONTROL5.2 Bash Variables
HISTCONTROL5.2 Bash Variables
HISTFILE5.2 Bash Variables
HISTFILE5.2 Bash Variables
HISTFILESIZE5.2 Bash Variables
HISTFILESIZE5.2 Bash Variables
HISTIGNORE5.2 Bash Variables
HISTIGNORE5.2 Bash Variables
history-preserve-point8.3.1 Readline Init File Syntax
HISTSIZE5.2 Bash Variables
HISTSIZE5.2 Bash Variables
HISTTIMEFORMAT5.2 Bash Variables
HISTTIMEFORMAT5.2 Bash Variables
HOME5.1 Bourne Shell Variables
HOME5.1 Bourne Shell Variables
horizontal-scroll-mode8.3.1 Readline Init File Syntax
HOSTFILE5.2 Bash Variables
HOSTFILE5.2 Bash Variables
HOSTNAME5.2 Bash Variables
HOSTNAME5.2 Bash Variables
HOSTTYPE5.2 Bash Variables
HOSTTYPE5.2 Bash Variables
I
IFS5.1 Bourne Shell Variables
IFS5.1 Bourne Shell Variables
IGNOREEOF5.2 Bash Variables
IGNOREEOF5.2 Bash Variables
input-meta8.3.1 Readline Init File Syntax
INPUTRC5.2 Bash Variables
INPUTRC5.2 Bash Variables
isearch-terminators8.3.1 Readline Init File Syntax
K
keymap8.3.1 Readline Init File Syntax
L
LANG5.2 Bash Variables
LANG5.2 Bash Variables
LC_ALL5.2 Bash Variables
LC_ALL5.2 Bash Variables
LC_COLLATE5.2 Bash Variables
LC_COLLATE5.2 Bash Variables
LC_CTYPE5.2 Bash Variables
LC_CTYPE5.2 Bash Variables
LC_MESSAGES3.1.2.5 Locale-Specific Translation
LC_MESSAGES5.2 Bash Variables
LC_MESSAGES5.2 Bash Variables
LC_NUMERIC5.2 Bash Variables
LC_NUMERIC5.2 Bash Variables
LINENO5.2 Bash Variables
LINENO5.2 Bash Variables
LINES5.2 Bash Variables
LINES5.2 Bash Variables
M
MACHTYPE5.2 Bash Variables
MACHTYPE5.2 Bash Variables
MAIL5.1 Bourne Shell Variables
MAIL5.1 Bourne Shell Variables
MAILCHECK5.2 Bash Variables
MAILCHECK5.2 Bash Variables
MAILPATH5.1 Bourne Shell Variables
MAILPATH5.1 Bourne Shell Variables
mark-modified-lines8.3.1 Readline Init File Syntax
mark-symlinked-directories8.3.1 Readline Init File Syntax
match-hidden-files8.3.1 Readline Init File Syntax
meta-flag8.3.1 Readline Init File Syntax
O
OLDPWD5.2 Bash Variables
OLDPWD5.2 Bash Variables
OPTARG5.1 Bourne Shell Variables
OPTARG5.1 Bourne Shell Variables
OPTERR5.2 Bash Variables
OPTERR5.2 Bash Variables
OPTIND5.1 Bourne Shell Variables
OPTIND5.1 Bourne Shell Variables
OSTYPE5.2 Bash Variables
OSTYPE5.2 Bash Variables
output-meta8.3.1 Readline Init File Syntax
P
page-completions8.3.1 Readline Init File Syntax
PATH5.1 Bourne Shell Variables
PATH5.1 Bourne Shell Variables
PIPESTATUS5.2 Bash Variables
PIPESTATUS5.2 Bash Variables
POSIXLY_CORRECT5.2 Bash Variables
POSIXLY_CORRECT5.2 Bash Variables
PPID5.2 Bash Variables
PPID5.2 Bash Variables
PROMPT_COMMAND5.2 Bash Variables
PROMPT_COMMAND5.2 Bash Variables
PS15.1 Bourne Shell Variables
PS15.1 Bourne Shell Variables
PS25.1 Bourne Shell Variables
PS25.1 Bourne Shell Variables
PS35.2 Bash Variables
PS35.2 Bash Variables
PS45.2 Bash Variables
PS45.2 Bash Variables
PWD5.2 Bash Variables
PWD5.2 Bash Variables
R
RANDOM5.2 Bash Variables
RANDOM5.2 Bash Variables
REPLY5.2 Bash Variables
REPLY5.2 Bash Variables
S
SECONDS5.2 Bash Variables
SECONDS5.2 Bash Variables
SHELL5.2 Bash Variables
SHELL5.2 Bash Variables
SHELLOPTS5.2 Bash Variables
SHELLOPTS5.2 Bash Variables
SHLVL5.2 Bash Variables
SHLVL5.2 Bash Variables
show-all-if-ambiguous8.3.1 Readline Init File Syntax
show-all-if-unmodified8.3.1 Readline Init File Syntax
T
TEXTDOMAIN3.1.2.5 Locale-Specific Translation
TEXTDOMAINDIR3.1.2.5 Locale-Specific Translation
TIMEFORMAT5.2 Bash Variables
TIMEFORMAT5.2 Bash Variables
TMOUT5.2 Bash Variables
TMOUT5.2 Bash Variables
TMPDIR5.2 Bash Variables
TMPDIR5.2 Bash Variables
U
UID5.2 Bash Variables
UID5.2 Bash Variables
V
visible-stats8.3.1 Readline Init File Syntax

Jump to:   ! +   +# +   +$ +   +* +   +- +   +0 +   +? +   +@ +   +_ +   +
+A +   +B +   +C +   +D +   +E +   +F +   +G +   +H +   +I +   +K +   +L +   +M +   +O +   +P +   +R +   +S +   +T +   +U +   +V +   +

+ + +

+ + + + + + + + + + + +
[ < ][ > ]   [ << ][ Up ][ >> ]         [Top][Contents][Index][ ? ]
+

D.4 Function Index

+ +
Jump to:   A +   +B +   +C +   +D +   +E +   +F +   +G +   +H +   +I +   +K +   +M +   +N +   +O +   +P +   +Q +   +R +   +S +   +T +   +U +   +Y +   +

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
Index Entry Section
A
abort (C-g)8.4.8 Some Miscellaneous Commands
abort (C-g)8.4.8 Some Miscellaneous Commands
accept-line (Newline or Return)8.4.2 Commands For Manipulating The History
accept-line (Newline or Return)8.4.2 Commands For Manipulating The History
alias-expand-line ()8.4.8 Some Miscellaneous Commands
alias-expand-line ()8.4.8 Some Miscellaneous Commands
B
backward-char (C-b)8.4.1 Commands For Moving
backward-char (C-b)8.4.1 Commands For Moving
backward-delete-char (Rubout)8.4.3 Commands For Changing Text
backward-delete-char (Rubout)8.4.3 Commands For Changing Text
backward-kill-line (C-x Rubout)8.4.4 Killing And Yanking
backward-kill-line (C-x Rubout)8.4.4 Killing And Yanking
backward-kill-word (M-DEL)8.4.4 Killing And Yanking
backward-kill-word (M-DEL)8.4.4 Killing And Yanking
backward-word (M-b)8.4.1 Commands For Moving
backward-word (M-b)8.4.1 Commands For Moving
beginning-of-history (M-&#60;)8.4.2 Commands For Manipulating The History
beginning-of-history (M-&#60;)8.4.2 Commands For Manipulating The History
beginning-of-line (C-a)8.4.1 Commands For Moving
beginning-of-line (C-a)8.4.1 Commands For Moving
C
call-last-kbd-macro (C-x e)8.4.7 Keyboard Macros
call-last-kbd-macro (C-x e)8.4.7 Keyboard Macros
capitalize-word (M-c)8.4.3 Commands For Changing Text
capitalize-word (M-c)8.4.3 Commands For Changing Text
character-search (C-])8.4.8 Some Miscellaneous Commands
character-search (C-])8.4.8 Some Miscellaneous Commands
character-search-backward (M-C-])8.4.8 Some Miscellaneous Commands
character-search-backward (M-C-])8.4.8 Some Miscellaneous Commands
clear-screen (C-l)8.4.1 Commands For Moving
clear-screen (C-l)8.4.1 Commands For Moving
complete (TAB)8.4.6 Letting Readline Type For You
complete (TAB)8.4.6 Letting Readline Type For You
complete-command (M-!)8.4.6 Letting Readline Type For You
complete-command (M-!)8.4.6 Letting Readline Type For You
complete-filename (M-/)8.4.6 Letting Readline Type For You
complete-filename (M-/)8.4.6 Letting Readline Type For You
complete-hostname (M-@)8.4.6 Letting Readline Type For You
complete-hostname (M-@)8.4.6 Letting Readline Type For You
complete-into-braces (M-{)8.4.6 Letting Readline Type For You
complete-into-braces (M-{)8.4.6 Letting Readline Type For You
complete-username (M-~)8.4.6 Letting Readline Type For You
complete-username (M-~)8.4.6 Letting Readline Type For You
complete-variable (M-$)8.4.6 Letting Readline Type For You
complete-variable (M-$)8.4.6 Letting Readline Type For You
copy-backward-word ()8.4.4 Killing And Yanking
copy-backward-word ()8.4.4 Killing And Yanking
copy-forward-word ()8.4.4 Killing And Yanking
copy-forward-word ()8.4.4 Killing And Yanking
copy-region-as-kill ()8.4.4 Killing And Yanking
copy-region-as-kill ()8.4.4 Killing And Yanking
D
delete-char (C-d)8.4.3 Commands For Changing Text
delete-char (C-d)8.4.3 Commands For Changing Text
delete-char-or-list ()8.4.6 Letting Readline Type For You
delete-char-or-list ()8.4.6 Letting Readline Type For You
delete-horizontal-space ()8.4.4 Killing And Yanking
delete-horizontal-space ()8.4.4 Killing And Yanking
digit-argument (M-0, M-1, <small>...</small> M--)8.4.5 Specifying Numeric Arguments
digit-argument (M-0, M-1, <small>...</small> M--)8.4.5 Specifying Numeric Arguments
display-shell-version (C-x C-v)8.4.8 Some Miscellaneous Commands
display-shell-version (C-x C-v)8.4.8 Some Miscellaneous Commands
do-uppercase-version (M-a, M-b, M-x, <small>...</small>)8.4.8 Some Miscellaneous Commands
do-uppercase-version (M-a, M-b, M-x, <small>...</small>)8.4.8 Some Miscellaneous Commands
downcase-word (M-l)8.4.3 Commands For Changing Text
downcase-word (M-l)8.4.3 Commands For Changing Text
dump-functions ()8.4.8 Some Miscellaneous Commands
dump-functions ()8.4.8 Some Miscellaneous Commands
dump-macros ()8.4.8 Some Miscellaneous Commands
dump-macros ()8.4.8 Some Miscellaneous Commands
dump-variables ()8.4.8 Some Miscellaneous Commands
dump-variables ()8.4.8 Some Miscellaneous Commands
dynamic-complete-history (M-TAB)8.4.6 Letting Readline Type For You
dynamic-complete-history (M-TAB)8.4.6 Letting Readline Type For You
E
edit-and-execute-command (C-xC-e)8.4.8 Some Miscellaneous Commands
edit-and-execute-command (C-xC-e)8.4.8 Some Miscellaneous Commands
end-kbd-macro (C-x ))8.4.7 Keyboard Macros
end-kbd-macro (C-x ))8.4.7 Keyboard Macros
end-of-history (M-&#62;)8.4.2 Commands For Manipulating The History
end-of-history (M-&#62;)8.4.2 Commands For Manipulating The History
end-of-line (C-e)8.4.1 Commands For Moving
end-of-line (C-e)8.4.1 Commands For Moving
exchange-point-and-mark (C-x C-x)8.4.8 Some Miscellaneous Commands
exchange-point-and-mark (C-x C-x)8.4.8 Some Miscellaneous Commands
F
forward-backward-delete-char ()8.4.3 Commands For Changing Text
forward-backward-delete-char ()8.4.3 Commands For Changing Text
forward-char (C-f)8.4.1 Commands For Moving
forward-char (C-f)8.4.1 Commands For Moving
forward-search-history (C-s)8.4.2 Commands For Manipulating The History
forward-search-history (C-s)8.4.2 Commands For Manipulating The History
forward-word (M-f)8.4.1 Commands For Moving
forward-word (M-f)8.4.1 Commands For Moving
G
glob-complete-word (M-g)8.4.8 Some Miscellaneous Commands
glob-complete-word (M-g)8.4.8 Some Miscellaneous Commands
glob-expand-word (C-x *)8.4.8 Some Miscellaneous Commands
glob-expand-word (C-x *)8.4.8 Some Miscellaneous Commands
glob-list-expansions (C-x g)8.4.8 Some Miscellaneous Commands
glob-list-expansions (C-x g)8.4.8 Some Miscellaneous Commands
H
history-and-alias-expand-line ()8.4.8 Some Miscellaneous Commands
history-and-alias-expand-line ()8.4.8 Some Miscellaneous Commands
history-expand-line (M-^)8.4.8 Some Miscellaneous Commands
history-expand-line (M-^)8.4.8 Some Miscellaneous Commands
history-search-backward ()8.4.2 Commands For Manipulating The History
history-search-backward ()8.4.2 Commands For Manipulating The History
history-search-forward ()8.4.2 Commands For Manipulating The History
history-search-forward ()8.4.2 Commands For Manipulating The History
I
insert-comment (M-#)8.4.8 Some Miscellaneous Commands
insert-comment (M-#)8.4.8 Some Miscellaneous Commands
insert-completions (M-*)8.4.6 Letting Readline Type For You
insert-completions (M-*)8.4.6 Letting Readline Type For You
insert-last-argument (M-. or M-_)8.4.8 Some Miscellaneous Commands
insert-last-argument (M-. or M-_)8.4.8 Some Miscellaneous Commands
K
kill-line (C-k)8.4.4 Killing And Yanking
kill-line (C-k)8.4.4 Killing And Yanking
kill-region ()8.4.4 Killing And Yanking
kill-region ()8.4.4 Killing And Yanking
kill-whole-line ()8.4.4 Killing And Yanking
kill-whole-line ()8.4.4 Killing And Yanking
kill-word (M-d)8.4.4 Killing And Yanking
kill-word (M-d)8.4.4 Killing And Yanking
M
magic-space ()8.4.8 Some Miscellaneous Commands
magic-space ()8.4.8 Some Miscellaneous Commands
menu-complete ()8.4.6 Letting Readline Type For You
menu-complete ()8.4.6 Letting Readline Type For You
N
next-history (C-n)8.4.2 Commands For Manipulating The History
next-history (C-n)8.4.2 Commands For Manipulating The History
non-incremental-forward-search-history (M-n)8.4.2 Commands For Manipulating The History
non-incremental-forward-search-history (M-n)8.4.2 Commands For Manipulating The History
non-incremental-reverse-search-history (M-p)8.4.2 Commands For Manipulating The History
non-incremental-reverse-search-history (M-p)8.4.2 Commands For Manipulating The History
O
operate-and-get-next (C-o)8.4.8 Some Miscellaneous Commands
operate-and-get-next (C-o)8.4.8 Some Miscellaneous Commands
overwrite-mode ()8.4.3 Commands For Changing Text
overwrite-mode ()8.4.3 Commands For Changing Text
P
possible-command-completions (C-x !)8.4.6 Letting Readline Type For You
possible-command-completions (C-x !)8.4.6 Letting Readline Type For You
possible-completions (M-?)8.4.6 Letting Readline Type For You
possible-completions (M-?)8.4.6 Letting Readline Type For You
possible-filename-completions (C-x /)8.4.6 Letting Readline Type For You
possible-filename-completions (C-x /)8.4.6 Letting Readline Type For You
possible-hostname-completions (C-x @)8.4.6 Letting Readline Type For You
possible-hostname-completions (C-x @)8.4.6 Letting Readline Type For You
possible-username-completions (C-x ~)8.4.6 Letting Readline Type For You
possible-username-completions (C-x ~)8.4.6 Letting Readline Type For You
possible-variable-completions (C-x $)8.4.6 Letting Readline Type For You
possible-variable-completions (C-x $)8.4.6 Letting Readline Type For You
prefix-meta (ESC)8.4.8 Some Miscellaneous Commands
prefix-meta (ESC)8.4.8 Some Miscellaneous Commands
previous-history (C-p)8.4.2 Commands For Manipulating The History
previous-history (C-p)8.4.2 Commands For Manipulating The History
Q
quoted-insert (C-q or C-v)8.4.3 Commands For Changing Text
quoted-insert (C-q or C-v)8.4.3 Commands For Changing Text
R
re-read-init-file (C-x C-r)8.4.8 Some Miscellaneous Commands
re-read-init-file (C-x C-r)8.4.8 Some Miscellaneous Commands
redraw-current-line ()8.4.1 Commands For Moving
redraw-current-line ()8.4.1 Commands For Moving
reverse-search-history (C-r)8.4.2 Commands For Manipulating The History
reverse-search-history (C-r)8.4.2 Commands For Manipulating The History
revert-line (M-r)8.4.8 Some Miscellaneous Commands
revert-line (M-r)8.4.8 Some Miscellaneous Commands
S
self-insert (a, b, A, 1, !, <small>...</small>)8.4.3 Commands For Changing Text
self-insert (a, b, A, 1, !, <small>...</small>)8.4.3 Commands For Changing Text
set-mark (C-@)8.4.8 Some Miscellaneous Commands
set-mark (C-@)8.4.8 Some Miscellaneous Commands
shell-expand-line (M-C-e)8.4.8 Some Miscellaneous Commands
shell-expand-line (M-C-e)8.4.8 Some Miscellaneous Commands
start-kbd-macro (C-x ()8.4.7 Keyboard Macros
start-kbd-macro (C-x ()8.4.7 Keyboard Macros
T
tilde-expand (M-&#38;)8.4.8 Some Miscellaneous Commands
tilde-expand (M-&#38;)8.4.8 Some Miscellaneous Commands
transpose-chars (C-t)8.4.3 Commands For Changing Text
transpose-chars (C-t)8.4.3 Commands For Changing Text
transpose-words (M-t)8.4.3 Commands For Changing Text
transpose-words (M-t)8.4.3 Commands For Changing Text
U
undo (C-_ or C-x C-u)8.4.8 Some Miscellaneous Commands
undo (C-_ or C-x C-u)8.4.8 Some Miscellaneous Commands
universal-argument ()8.4.5 Specifying Numeric Arguments
universal-argument ()8.4.5 Specifying Numeric Arguments
unix-filename-rubout ()8.4.4 Killing And Yanking
unix-filename-rubout ()8.4.4 Killing And Yanking
unix-line-discard (C-u)8.4.4 Killing And Yanking
unix-line-discard (C-u)8.4.4 Killing And Yanking
unix-word-rubout (C-w)8.4.4 Killing And Yanking
unix-word-rubout (C-w)8.4.4 Killing And Yanking
upcase-word (M-u)8.4.3 Commands For Changing Text
upcase-word (M-u)8.4.3 Commands For Changing Text
Y
yank (C-y)8.4.4 Killing And Yanking
yank (C-y)8.4.4 Killing And Yanking
yank-last-arg (M-. or M-_)8.4.2 Commands For Manipulating The History
yank-last-arg (M-. or M-_)8.4.2 Commands For Manipulating The History
yank-nth-arg (M-C-y)8.4.2 Commands For Manipulating The History
yank-nth-arg (M-C-y)8.4.2 Commands For Manipulating The History
yank-pop (M-y)8.4.4 Killing And Yanking
yank-pop (M-y)8.4.4 Killing And Yanking

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+ + +

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[ < ][ > ]   [ << ][ Up ][ >> ]         [Top][Contents][Index][ ? ]
+

D.5 Concept Index

+ +
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Index Entry Section
A
alias expansion6.6 Aliases
arithmetic evaluation6.5 Shell Arithmetic
arithmetic expansion3.5.5 Arithmetic Expansion
arithmetic, shell6.5 Shell Arithmetic
arrays6.7 Arrays
B
background7.1 Job Control Basics
Bash configuration10.1 Basic Installation
Bash installation10.1 Basic Installation
Bourne shell3. Basic Shell Features
brace expansion3.5.1 Brace Expansion
builtin2. Definitions
C
command editing8.2.1 Readline Bare Essentials
command execution3.7.2 Command Search and Execution
command expansion3.7.1 Simple Command Expansion
command history9.1 Bash History Facilities
command search3.7.2 Command Search and Execution
command substitution3.5.4 Command Substitution
command timing3.2.2 Pipelines
commands, compound3.2.4 Compound Commands
commands, conditional3.2.4.2 Conditional Constructs
commands, grouping3.2.4.3 Grouping Commands
commands, lists3.2.3 Lists of Commands
commands, looping3.2.4.1 Looping Constructs
commands, pipelines3.2.2 Pipelines
commands, shell3.2 Shell Commands
commands, simple3.2.1 Simple Commands
comments, shell3.1.3 Comments
completion builtins8.7 Programmable Completion Builtins
configuration10.1 Basic Installation
control operator2. Definitions
D
directory stack6.8 The Directory Stack
E
editing command lines8.2.1 Readline Bare Essentials
environment3.7.4 Environment
evaluation, arithmetic6.5 Shell Arithmetic
event designators9.3.1 Event Designators
execution environment3.7.3 Command Execution Environment
exit status2. Definitions
exit status3.7.5 Exit Status
expansion3.5 Shell Expansions
expansion, arithmetic3.5.5 Arithmetic Expansion
expansion, brace3.5.1 Brace Expansion
expansion, filename3.5.8 Filename Expansion
expansion, parameter3.5.3 Shell Parameter Expansion
expansion, pathname3.5.8 Filename Expansion
expansion, tilde3.5.2 Tilde Expansion
expressions, arithmetic6.5 Shell Arithmetic
expressions, conditional6.4 Bash Conditional Expressions
F
FDL, GNU Free Documentation LicenseC.1 GNU Free Documentation License
field2. Definitions
filename2. Definitions
filename expansion3.5.8 Filename Expansion
foreground7.1 Job Control Basics
functions, shell3.3 Shell Functions
H
history builtins9.2 Bash History Builtins
history events9.3.1 Event Designators
history expansion9.3 History Expansion
history list9.1 Bash History Facilities
History, how to use8.7 Programmable Completion Builtins
I
identifier2. Definitions
initialization file, readline8.3 Readline Init File
installation10.1 Basic Installation
interaction, readline8.2 Readline Interaction
interactive shell6.1 Invoking Bash
interactive shell6.3 Interactive Shells
internationalization3.1.2.5 Locale-Specific Translation
J
job2. Definitions
job control2. Definitions
job control7.1 Job Control Basics
K
kill ring8.2.3 Readline Killing Commands
killing text8.2.3 Readline Killing Commands
L
localization3.1.2.5 Locale-Specific Translation
login shell6.1 Invoking Bash
M
matching, pattern3.5.8.1 Pattern Matching
metacharacter2. Definitions
N
name2. Definitions
native languages3.1.2.5 Locale-Specific Translation
notation, readline8.2.1 Readline Bare Essentials
O
operator, shell2. Definitions
P
parameter expansion3.5.3 Shell Parameter Expansion
parameters3.4 Shell Parameters
parameters, positional3.4.1 Positional Parameters
parameters, special3.4.2 Special Parameters
pathname expansion3.5.8 Filename Expansion
pattern matching3.5.8.1 Pattern Matching
pipeline3.2.2 Pipelines
POSIX2. Definitions
POSIX Mode6.11 Bash POSIX Mode
process group2. Definitions
process group ID2. Definitions
process substitution3.5.6 Process Substitution
programmable completion8.6 Programmable Completion
prompting6.9 Controlling the Prompt
Q
quoting3.1.2 Quoting
quoting, ANSI3.1.2.4 ANSI-C Quoting
R
Readline, how to use7.3 Job Control Variables
redirection3.6 Redirections
reserved word2. Definitions
restricted shell6.10 The Restricted Shell
return status2. Definitions
S
shell arithmetic6.5 Shell Arithmetic
shell function3.3 Shell Functions
shell script3.8 Shell Scripts
shell variable3.4 Shell Parameters
shell, interactive6.3 Interactive Shells
signal2. Definitions
signal handling3.7.6 Signals
special builtin2. Definitions
special builtin4.4 Special Builtins
startup files6.2 Bash Startup Files
suspending jobs7.1 Job Control Basics
T
tilde expansion3.5.2 Tilde Expansion
token2. Definitions
translation, native languages3.1.2.5 Locale-Specific Translation
V
variable, shell3.4 Shell Parameters
variables, readline8.3.1 Readline Init File Syntax
W
word2. Definitions
word splitting3.5.7 Word Splitting
Y
yanking text8.2.3 Readline Killing Commands

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+ +

+ + + + + + +
[Top][Contents][Index][ ? ]
+

Table of Contents

+ +
+ + + + + + +
[Top][Contents][Index][ ? ]
+

Short Table of Contents

+
+1. Introduction +
+2. Definitions +
+3. Basic Shell Features +
+4. Shell Builtin Commands +
+5. Shell Variables +
+6. Bash Features +
+7. Job Control +
+8. Command Line Editing +
+9. Using History Interactively +
+10. Installing Bash +
+A. Reporting Bugs +
+B. Major Differences From The Bourne Shell +
+C. Copying This Manual +
+D. Indexes +
+ +
+
+ + + + + + +
[Top][Contents][Index][ ? ]
+

About this document

+This document was generated by Chet Ramey on January, 11 2007 +using texi2html +

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+
+ +This document was generated +by Chet Ramey on January, 11 2007 +using texi2html + + + diff --git a/doc/bash.1 b/doc/bash.1 index 9f22755e0..cbcd50148 100644 --- a/doc/bash.1 +++ b/doc/bash.1 @@ -6,12 +6,12 @@ .\" Case Western Reserve University .\" chet@po.cwru.edu .\" -.\" Last Change: Tue Dec 26 19:01:54 EST 2006 +.\" Last Change: Fri Jan 12 16:29:22 EST 2007 .\" .\" bash_builtins, strip all but Built-Ins section .if \n(zZ=1 .ig zZ .if \n(zY=1 .ig zY -.TH BASH 1 "2006 December 26" "GNU Bash-3.2" +.TH BASH 1 "2007 January 12" "GNU Bash-3.2" .\" .\" There's some problem with having a `@' .\" in a tagged paragraph with the BSD man macros. @@ -51,8 +51,8 @@ bash \- GNU Bourne-Again SHell [options] [file] .SH COPYRIGHT -.if n Bash is Copyright (C) 1989-2005 by the Free Software Foundation, Inc. -.if t Bash is Copyright \(co 1989-2005 by the Free Software Foundation, Inc. +.if n Bash is Copyright (C) 1989-2007 by the Free Software Foundation, Inc. +.if t Bash is Copyright \(co 1989-2007 by the Free Software Foundation, Inc. .SH DESCRIPTION .B Bash is an \fBsh\fR-compatible command language interpreter that @@ -1752,6 +1752,8 @@ for \fIstrftime\fP(3) to print the time stamp associated with each history entry displayed by the \fBhistory\fP builtin. If this variable is set, time stamps are written to the history file so they may be preserved across shell sessions. +This uses the history comment character to distinguish timestamps from +other history lines. .TP .B HOME The home directory of the current user; the default argument for the @@ -5611,6 +5613,13 @@ is truncated, if necessary, to contain no more than the number of lines specified by the value of .SM .BR HISTFILESIZE . +When the history file is read, +lines beginning with the history comment character followed immediately +by a digit are interpreted as timestamps for the preceding history line. +These timestamps are optionally displayed depending on the value of the +.SM +.B HISTTIMEFORMAT +variable. When an interactive shell exits, the last .SM .B $HISTSIZE @@ -5631,7 +5640,16 @@ If .SM .B HISTFILE is unset, or if the history file is unwritable, the history is -not saved. After saving the history, the history file is truncated +not saved. +If the +.SM +.HISTTIMEFORMAT +variable is set, time stamps are written to the history file, marked +with the history comment character, so +they may be preserved across shell sessions. +This uses the history comment character to distinguish timestamps from +other history lines. +After saving the history, the history file is truncated to contain no more than .SM .B HISTFILESIZE @@ -5765,6 +5783,9 @@ history expansion mechanism (see the description of .B histchars above under .BR "Shell Variables" ). +The shell uses +the history comment character to mark history timestamps when +writing the history file. .SS Event Designators .PP An event designator is a reference to a command line entry in the @@ -7169,7 +7190,11 @@ are added. .PD .PP If the \fBHISTTIMEFORMAT\fP is set, the time stamp information -associated with each history entry is written to the history file. +associated with each history entry is written to the history file, +marked with the history comment character. +When the history file is read, lines beginning with the history +comment character followed immediately by a digit are interpreted +as timestamps for the previous history line. The return value is 0 unless an invalid option is encountered, an error occurs while reading or writing the history file, an invalid \fIoffset\fP is supplied as an argument to \fB\-d\fP, or the diff --git a/doc/bash.1.orig b/doc/bash.1.orig index 828ec966b..9f22755e0 100644 --- a/doc/bash.1.orig +++ b/doc/bash.1.orig @@ -4,14 +4,14 @@ .\" Chet Ramey .\" Information Network Services .\" Case Western Reserve University -.\" chet@po.CWRU.Edu +.\" chet@po.cwru.edu .\" -.\" Last Change: Mon Apr 14 17:57:24 EDT 2003 +.\" Last Change: Tue Dec 26 19:01:54 EST 2006 .\" .\" bash_builtins, strip all but Built-Ins section .if \n(zZ=1 .ig zZ .if \n(zY=1 .ig zY -.TH BASH 1 "2003 April 14" "GNU Bash-3.0" +.TH BASH 1 "2006 December 26" "GNU Bash-3.2" .\" .\" There's some problem with having a `@' .\" in a tagged paragraph with the BSD man macros. @@ -51,8 +51,8 @@ bash \- GNU Bourne-Again SHell [options] [file] .SH COPYRIGHT -.if n Bash is Copyright (C) 1989-2002 by the Free Software Foundation, Inc. -.if t Bash is Copyright \(co 1989-2002 by the Free Software Foundation, Inc. +.if n Bash is Copyright (C) 1989-2005 by the Free Software Foundation, Inc. +.if t Bash is Copyright \(co 1989-2005 by the Free Software Foundation, Inc. .SH DESCRIPTION .B Bash is an \fBsh\fR-compatible command language interpreter that @@ -62,8 +62,11 @@ also incorporates useful features from the \fIKorn\fP and \fIC\fP shells (\fBksh\fP and \fBcsh\fP). .PP .B Bash -is intended to be a conformant implementation of the IEEE -POSIX Shell and Tools specification (IEEE Working Group 1003\.2). +is intended to be a conformant implementation of the +Shell and Utilities portion of the IEEE POSIX specification +(IEEE Standard 1003.1). +.B Bash +can be configured to be POSIX-conformant by default. .SH OPTIONS In addition to the single-character shell options documented in the description of the \fBset\fR builtin command, \fBbash\fR @@ -115,7 +118,7 @@ when invoking an interactive shell. .TP .B \-D A list of all double-quoted strings preceded by \fB$\fP -is printed on the standard ouput. +is printed on the standard output. These are the strings that are subject to language translation when the current locale is not \fBC\fP or \fBPOSIX\fP. @@ -154,11 +157,13 @@ single-character options to be recognized. .TP .B \-\-debugger Arrange for the debugger profile to be executed before the shell -starts. Turns on extended debugging mode (see the description of the +starts. +Turns on extended debugging mode (see the description of the .B extdebug option to the .B shopt -builtin below) and shell function tracing (see the description of the +builtin below) +and shell function tracing (see the description of the \fB\-o functrace\fP option to the .B set builtin below). @@ -219,7 +224,7 @@ This option is on by default if the shell is invoked as .TP .B \-\-posix Change the behavior of \fBbash\fP where the default operation differs -from the POSIX 1003.2 standard to match the standard (\fIposix mode\fP). +from the POSIX standard to match the standard (\fIposix mode\fP). .TP .B \-\-restricted The shell becomes restricted (see @@ -269,7 +274,7 @@ An \fIinteractive\fP shell is one started without non-option arguments and without the .B \-c option -whose standard input and output are +whose standard input and error are both connected to terminals (as determined by .IR isatty (3)), or one started with the @@ -487,7 +492,6 @@ command: .if n ! case do done elif else esac fi for function if in select then until while { } time [[ ]] .if t ! case do done elif else esac fi for function if in select then until while { } time [[ ]] .if t .RE -.RE .SH "SHELL GRAMMAR" .SS Simple Commands .PP @@ -521,12 +525,15 @@ command (see .B REDIRECTION below). .PP +The return status of a pipeline is the exit status of the last +command, unless the \fBpipefail\fP option is enabled. +If \fBpipefail\fP is enabled, the pipeline's return status is the +value of the last (rightmost) command to exit with a non-zero status, +or zero if all commands exit successfully. If the reserved word .B ! -precedes a pipeline, the exit status of that -pipeline is the logical NOT of the exit status of the last command. -Otherwise, the status of the pipeline is the exit status of the last -command. +precedes a pipeline, the exit status of that pipeline is the logical +negation of the exit status as described above. The shell waits for all commands in the pipeline to terminate before returning a value. .PP @@ -621,7 +628,11 @@ executed in the list. A \fIcompound command\fP is one of the following: .TP (\fIlist\fP) -\fIlist\fP is executed in a subshell. Variable assignments and builtin +\fIlist\fP is executed in a subshell environment (see +.SM +\fBCOMMAND EXECUTION ENVIRONMENT\fP +below). +Variable assignments and builtin commands that affect the shell's environment do not remain in effect after the command completes. The return status is the exit status of \fIlist\fP. @@ -663,12 +674,36 @@ as primaries. When the \fB==\fP and \fB!=\fP operators are used, the string to the right of the operator is considered a pattern and matched according to the rules described below under \fBPattern Matching\fP. -The return value is 0 if the string matches or does not match -the pattern, respectively, and 1 otherwise. +If the shell option +.B nocasematch +is enabled, the match is performed without regard to the case +of alphabetic characters. +The return value is 0 if the string matches (\fB==\fP) or does not match +(\fB!=\fP) the pattern, and 1 otherwise. Any part of the pattern may be quoted to force it to be matched as a string. .if t .sp 0.5 .if n .sp 1 +An additional binary operator, \fB=~\fP, is available, with the same +precedence as \fB==\fP and \fB!=\fP. +When it is used, the string to the right of the operator is considered +an extended regular expression and matched accordingly (as in \fIregex\fP(3)). +The return value is 0 if the string matches +the pattern, and 1 otherwise. +If the regular expression is syntactically incorrect, the conditional +expression's return value is 2. +If the shell option +.B nocasematch +is enabled, the match is performed without regard to the case +of alphabetic characters. +Substrings matched by parenthesized subexpressions within the regular +expression are saved in the array variable \fBBASH_REMATCH\fP. +The element of \fBBASH_REMATCH\fP with index 0 is the portion of the string +matching the entire regular expression. +The element of \fBBASH_REMATCH\fP with index \fIn\fP is the portion of the +string matching the \fIn\fPth parenthesized subexpression. +.if t .sp 0.5 +.if n .sp 1 Expressions may be combined using the following operators, listed in decreasing order of precedence: .if t .sp 0.5 @@ -772,7 +807,18 @@ A \fBcase\fP command first expands \fIword\fP, and tries to match it against each \fIpattern\fP in turn, using the same matching rules as for pathname expansion (see .B Pathname Expansion -below). When a match is found, the +below). +The \fIword\fP is expanded using tilde +expansion, parameter and variable expansion, arithmetic substitution, +command substitution, process substitution and quote removal. +Each \fIpattern\fP examined is expanded using tilde +expansion, parameter and variable expansion, arithmetic substitution, +command substitution, and process substitution. +If the shell option +.B nocasematch +is enabled, the match is performed without regard to the case +of alphabetic characters. +When a match is found, the corresponding \fIlist\fP is executed. After the first match, no subsequent matches are attempted. The exit status is zero if no pattern matches. Otherwise, it is the exit status of the @@ -811,15 +857,32 @@ The exit status of the \fBwhile\fP and \fBuntil\fP commands is the exit status of the last \fBdo\fP \fIlist\fP command executed, or zero if none was executed. -.TP -[ \fBfunction\fP ] \fIname\fP () { \fIlist\fP; } -This defines a function named \fIname\fP. The \fIbody\fP of the -function is the -.I list -of commands between { and }. This list -is executed whenever \fIname\fP is specified as the -name of a simple command. The exit status of a function is -the exit status of the last command executed in the body. (See +.SS Shell Function Definitions +.PP +A shell function is an object that is called like a simple command and +executes a compound command with a new set of positional parameters. +Shell functions are declared as follows: +.TP +[ \fBfunction\fP ] \fIname\fP () \fIcompound\-command\fP [\fIredirection\fP] +This defines a function named \fIname\fP. +The reserved word \fBfunction\fP is optional. +If the \fBfunction\fP reserved word is supplied, the parentheses are optional. +The \fIbody\fP of the function is the compound command +.I compound\-command +(see \fBCompound Commands\fP above). +That command is usually a \fIlist\fP of commands between { and }, but +may be any command listed under \fBCompound Commands\fP above. +\fIcompound\-command\fP is executed whenever \fIname\fP is specified as the +name of a simple command. +Any redirections (see +.SM +.B REDIRECTION +below) specified when a function is defined are performed +when the function is executed. +The exit status of a function definition is zero unless a syntax error +occurs or a readonly function with the same name already exists. +When executed, the exit status of a function is the exit status of the +last command executed in the body. (See .SM .B FUNCTIONS below.) @@ -852,7 +915,11 @@ Each of the \fImetacharacters\fP listed above under has special meaning to the shell and must be quoted if it is to represent itself. .PP -When the command history expansion facilities are being used, the +When the command history expansion facilities are being used +(see +.SM +.B HISTORY EXPANSION +below), the \fIhistory expansion\fP character, usually \fB!\fP, must be quoted to prevent history expansion. .PP @@ -876,8 +943,9 @@ Enclosing characters in double quotes preserves the literal value of all characters within the quotes, with the exception of .BR $ , .BR ` , -and -.BR \e . +.BR \e , +and, when history expansion is enabled, +.BR ! . The characters .B $ and @@ -893,8 +961,12 @@ or .BR . A double quote may be quoted within double quotes by preceding it with a backslash. -When command history is being used, the double quote may not be used to -quote the history expansion character. +If enabled, history expansion will be performed unless an +.B ! +appearing in double quotes is escaped using a backslash. +The backslash preceding the +.B ! +is not removed. .PP The special parameters .B * @@ -906,9 +978,9 @@ quotes (see .B PARAMETERS below). .PP -Words of the form \fB$\fP'\fIstring\fP' are treated specially. The +Words of the form \fB$\fP\(aq\fIstring\fP\(aq are treated specially. The word expands to \fIstring\fP, with backslash-escaped characters replaced -as specifed by the ANSI C standard. Backslash escape sequences, if +as specified by the ANSI C standard. Backslash escape sequences, if present, are decoded as follows: .RS .PD 0 @@ -940,7 +1012,7 @@ vertical tab .B \e\e backslash .TP -.B \e' +.B \e\(aq single quote .TP .B \e\fInnn\fP @@ -1025,6 +1097,7 @@ of \fB"$@"\fP as explained below under .BR "Special Parameters" . Pathname expansion is not performed. Assignment statements may also appear as arguments to the +.BR alias , .BR declare , .BR typeset , .BR export , @@ -1032,6 +1105,20 @@ Assignment statements may also appear as arguments to the and .B local builtin commands. +.PP +In the context where an assignment statement is assigning a value +to a shell variable or array index, the += operator can be used to +append to or add to the variable's previous value. +When += is applied to a variable for which the integer attribute has been +set, \fIvalue\fP is evaluated as an arithmetic expression and added to the +variable's current value, which is also evaluated. +When += is applied to an array variable using compound assignment (see +.B Arrays +below), the +variable's value is not unset (as it is when using =), and new values are +appended to the array beginning at one greater than the array's maximum index. +When applied to a string-valued variable, \fIvalue\fP is expanded and +appended to the variable's value. .SS Positional Parameters .PP A @@ -1086,6 +1173,10 @@ Expands to the positional parameters, starting from one. When the expansion occurs within double quotes, each parameter expands to a separate word. That is, "\fB$@\fP" is equivalent to "\fB$1\fP" "\fB$2\fP" ... +If the double-quoted expansion occurs within a word, the expansion of +the first parameter is joined with the beginning part of the original +word, and the expansion of the last parameter is joined with the last +part of the original word. When there are no positional parameters, "\fB$@\fP" and .B $@ expand to nothing (i.e., they are removed). @@ -1134,12 +1225,13 @@ to the file name used to invoke as given by argument zero. .TP .B _ -At shell startup, set to the absolute file name of the shell or shell -script being executed as passed in the argument list. +At shell startup, set to the absolute pathname used to invoke the +shell or shell script being executed as passed in the environment +or argument list. Subsequently, expands to the last argument to the previous command, after expansion. -Also set to the full file name of each command executed and placed in -the environment exported to that command. +Also set to the full pathname used to invoke each command executed +and placed in the environment exported to that command. When checking mail, this parameter holds the name of the mail file currently being checked. .PD @@ -1153,13 +1245,25 @@ The following variables are set by the shell: Expands to the full file name used to invoke this instance of .BR bash . .TP +.B BASHPID +Expands to the process id of the current bash process. +This differs from \fB$$\fP under certain circumstances, such as subshells +that do not require bash to be re-initialized. +.TP .B BASH_ARGC An array variable whose values are the number of parameters in each -frame of the current bash execution call stack. The number of +frame of the current bash execution call stack. +The number of parameters to the current subroutine (shell function or script executed -with \fB.\fP or \fBsource\fP) is at the top of the stack. When a -subroutine is executed, the number of parameters passed is pushed onto +with \fB.\fP or \fBsource\fP) is at the top of the stack. +When a subroutine is executed, the number of parameters passed is pushed onto \fBBASH_ARGC\fP. +The shell sets \fBBASH_ARGC\fP only when in extended debugging mode +(see the description of the +.B extdebug +option to the +.B shopt +builtin below) .TP .B BASH_ARGV An array variable containing all of the parameters in the current bash @@ -1167,6 +1271,12 @@ execution call stack. The final parameter of the last subroutine call is at the top of the stack; the first parameter of the initial call is at the bottom. When a subroutine is executed, the parameters supplied are pushed onto \fBBASH_ARGV\fP. +The shell sets \fBBASH_ARGV\fP only when in extended debugging mode +(see the description of the +.B extdebug +option to the +.B shopt +builtin below) .TP .B BASH_COMMAND The command currently being executed or about to be executed, unless the @@ -1178,12 +1288,21 @@ The command argument to the \fB\-c\fP invocation option. .TP .B BASH_LINENO An array variable whose members are the line numbers in source files -corresponding to each member of @var{FUNCNAME}. +corresponding to each member of \fBFUNCNAME\fP. \fB${BASH_LINENO[\fP\fI$i\fP\fB]}\fP is the line number in the source -file where \fB${FUNCNAME[\fP\fI$i + 1\fP\fB]}\fP was called. -The corresponding source file name is \fB${BASH_SOURCE[\fP\fI$i + 1\fP\fB]}\fB. +file where \fB${FUNCNAME[\fP\fI$ifP\fB]}\fP was called. +The corresponding source file name is \fB${BASH_SOURCE[\fP\fI$i\fP\fB]}\fB. Use \fBLINENO\fP to obtain the current line number. .TP +.B BASH_REMATCH +An array variable whose members are assigned by the \fB=~\fP binary +operator to the \fB[[\fP conditional command. +The element with index 0 is the portion of the string +matching the entire regular expression. +The element with index \fIn\fP is the portion of the +string matching the \fIn\fPth parenthesized subexpression. +This variable is read-only. +.TP .B BASH_SOURCE An array variable whose members are the source filenames corresponding to the elements in the \fBFUNCNAME\fP array variable. @@ -1232,6 +1351,10 @@ This variable is available only in shell functions invoked by the programmable completion facilities (see \fBProgrammable Completion\fP below). .TP +.B COMP_KEY +The key (or final key of a key sequence) used to invoke the current +completion function. +.TP .B COMP_LINE The current command line. This variable is available only in shell functions and external @@ -1249,6 +1372,20 @@ commands invoked by the programmable completion facilities (see \fBProgrammable Completion\fP below). .TP +.B COMP_TYPE +Set to an integer value corresponding to the type of completion attempted +that caused a completion function to be called: +\fITAB\fP, for normal completion, +\fI?\fP, for listing completions after successive tabs, +\fI!\fP, for listing alternatives on partial word completion, +\fI@\fP, to list completions if the word is not unmodified, +or +\fI%\fP, for menu completion. +This variable is available only in shell functions and external +commands invoked by the +programmable completion facilities (see \fBProgrammable Completion\fP +below). +.TP .B COMP_WORDBREAKS The set of characters that the Readline library treats as word separators when performing word completion. @@ -1261,6 +1398,8 @@ subsequently reset. .B COMP_WORDS An array variable (see \fBArrays\fP below) consisting of the individual words in the current command line. +The words are split on shell metacharacters as the shell parser would +separate them. This variable is available only in shell functions invoked by the programmable completion facilities (see \fBProgrammable Completion\fP below). @@ -1294,7 +1433,9 @@ An array variable containing the names of all shell functions currently in the execution call stack. The element with index 0 is the name of any currently-executing shell function. -The bottom-most element is "main". +The bottom-most element is +.if t \f(CW"main"\fP. +.if n "main". This variable exists only when a shell function is executing. Assignments to .SM @@ -1579,7 +1720,8 @@ command history is not saved when an interactive shell exits. .B HISTFILESIZE The maximum number of lines contained in the history file. When this variable is assigned a value, the history file is truncated, if -necessary, to contain no more than that number of lines. The default +necessary, by removing the oldest entries, +to contain no more than that number of lines. The default value is 500. The history file is also truncated to this size after writing it when an interactive shell exits. .TP @@ -1604,6 +1746,13 @@ The number of commands to remember in the command history (see .B HISTORY below). The default value is 500. .TP +.B HISTTIMEFORMAT +If this variable is set and not null, its value is used as a format string +for \fIstrftime\fP(3) to print the time stamp associated with each history +entry displayed by the \fBhistory\fP builtin. +If this variable is set, time stamps are written to the history file so +they may be preserved across shell sessions. +.TP .B HOME The home directory of the current user; the default argument for the \fBcd\fP builtin command. @@ -1725,7 +1874,7 @@ the current mailfile. Example: .RS .PP -\fBMAILPATH\fP='/var/mail/bfox?"You have mail":~/shell\-mail?"$_ has mail!"' +\fBMAILPATH\fP=\(aq/var/mail/bfox?"You have mail":~/shell\-mail?"$_ has mail!"\(aq .PP .B Bash supplies a default value for this variable, but the location of the user @@ -1761,8 +1910,8 @@ The default path is system-dependent, and is set by the administrator who installs .BR bash . A common value is -.if t \f(CW/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin:.\fP. -.if n ``/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin:.''. +.if t \f(CW/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin\fP. +.if n ``/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin''. .TP .B POSIXLY_CORRECT If this variable is in the environment when \fBbash\fP starts, the shell @@ -1810,6 +1959,12 @@ displays during an execution trace. The first character of is replicated multiple times, as necessary, to indicate multiple levels of indirection. The default is ``\fB+ \fP''. .TP +.B SHELL +The full pathname to the shell is kept in this environment variable. +If it is not set when the shell starts, +.B bash +assigns to it the full pathname of the current user's login shell. +.TP .B TIMEFORMAT The value of this parameter is used as a format string specifying how the timing information for pipelines prefixed with the @@ -1853,7 +2008,7 @@ The value of \fIp\fP determines whether or not the fraction is included. .IP If this variable is not set, \fBbash\fP acts as if it had the -value \fB$'\enreal\et%3lR\enuser\et%3lU\ensys\t%3lS'\fP. +value \fB$\(aq\enreal\et%3lR\enuser\et%3lU\ensys\t%3lS\(aq\fP. If the value is null, no timing information is displayed. A trailing newline is added when the format string is displayed. .TP @@ -1868,6 +2023,10 @@ number of seconds to wait for input after issuing the primary prompt. terminates after waiting for that number of seconds if input does not arrive. .TP +.B TMPDIR +If set, \fBBash\fP uses its value as the name of a directory in which +\fBBash\fP creates temporary files for the shell's use. +.TP .B auto_resume This variable controls how the shell interacts with the user and job control. If this variable is set, single word simple @@ -1893,9 +2052,7 @@ job identifier (see .B JOB CONTROL below). If set to any other value, the supplied string must be a prefix of a stopped job's name; this provides functionality -analogous to the -.B % -job identifier. +analogous to the \fB%\fP\fIstring\fP job identifier. .TP .B histchars The two or three characters which control history expansion @@ -1969,7 +2126,12 @@ character of the .B IFS special variable, and ${\fIname\fP[@]} expands each element of \fIname\fP to a separate word. When there are no array members, -${\fIname\fP[@]} expands to nothing. This is analogous to the expansion +${\fIname\fP[@]} expands to nothing. +If the double-quoted expansion occurs within a word, the expansion of +the first parameter is joined with the beginning part of the original +word, and the expansion of the last parameter is joined with the last +part of the original word. +This is analogous to the expansion of the special parameters \fB*\fP and \fB@\fP (see .B Special Parameters above). ${#\fIname\fP[\fIsubscript\fP]} expands to the length of @@ -1982,6 +2144,8 @@ The .B unset builtin is used to destroy arrays. \fBunset\fP \fIname\fP[\fIsubscript\fP] destroys the array element at index \fIsubscript\fP. +Care must be taken to avoid unwanted side effects caused by filename +generation. \fBunset\fP \fIname\fP, where \fIname\fP is an array, or \fBunset\fP \fIname\fP[\fIsubscript\fP], where \fIsubscript\fP is \fB*\fP or \fB@\fP, removes the entire array. @@ -2163,7 +2327,7 @@ is unchanged. Each variable assignment is checked for unquoted tilde-prefixes immediately following a .B : -or +or the first .BR = . In these cases, tilde expansion is also performed. Consequently, one may use file names with tildes in assignments to @@ -2186,7 +2350,7 @@ interpreted as part of the name. .PP When braces are used, the matching ending brace is the first `\fB}\fP' not escaped by a backslash or within a quoted string, and not within an -embedded arithmetic expansion, command substitution, or paramter +embedded arithmetic expansion, command substitution, or parameter expansion. .PP .PD 0 @@ -2286,8 +2450,14 @@ parameters beginning at \fIoffset\fP. If \fIparameter\fP is an array name indexed by @ or *, the result is the \fIlength\fP members of the array beginning with ${\fIparameter\fP[\fIoffset\fP]}. +A negative \fIoffset\fP is taken relative to one greater than the maximum +index of the specified array. +Note that a negative offset must be separated from the colon by at least +one space to avoid being confused with the :- expansion. Substring indexing is zero-based unless the positional parameters -are used, in which case the indexing starts at 1. +are used, in which case the indexing starts at 1 by default. +If \fIoffset\fP is 0, and the positional parameters are used, \fB$0\fP is +prefixed to the list. .TP ${\fB!\fP\fIprefix\fP\fB*\fP} .PD 0 @@ -2299,6 +2469,8 @@ separated by the first character of the .SM .B IFS special variable. +When \fI@\fP is used and the expansion appears within double quotes, each +variable name expands to a separate word. .TP ${\fB!\fP\fIname\fP[\fI@\fP]} .PD 0 @@ -2392,17 +2564,12 @@ the pattern removal operation is applied to each member of the array in turn, and the expansion is the resultant list. .TP ${\fIparameter\fP\fB/\fP\fIpattern\fP\fB/\fP\fIstring\fP} -.PD 0 -.TP -${\fIparameter\fP\fB//\fP\fIpattern\fP\fB/\fP\fIstring\fP} -.PD The \fIpattern\fP is expanded to produce a pattern just as in pathname expansion. \fIParameter\fP is expanded and the longest match of \fIpattern\fP against its value is replaced with \fIstring\fP. -In the first form, only the first match is replaced. -The second form causes all matches of \fIpattern\fP to be -replaced with \fIstring\fP. +If \Ipattern\fP begins with \fB/\fP, all matches of \fIpattern\fP are +replaced with \fIstring\fP. Normally only the first match is replaced. If \fIpattern\fP begins with \fB#\fP, it must match at the beginning of the expanded value of \fIparameter\fP. If \fIpattern\fP begins with \fB%\fP, it must match at the end @@ -2530,10 +2697,18 @@ is unset, or its value is exactly .BR , the default, then +sequences of +.BR , +.BR , +and +.B +at the beginning and end of the results of the previous +expansions are ignored, and any sequence of .SM .B IFS -characters serves to delimit words. If +characters not at the beginning or end serves to delimit words. +If .SM .B IFS has a value other than the default, then sequences of @@ -2569,7 +2744,7 @@ If the value of .B IFS is null, no word splitting occurs. .PP -Explicit null arguments (\^\f3"\^"\fP or \^\f3'\^'\fP\^) are retained. +Explicit null arguments (\^\f3"\^"\fP or \^\f3\(aq\^\(aq\fP\^) are retained. Unquoted implicit null arguments, resulting from the expansion of parameters that have no values, are removed. If a parameter with no value is expanded within double quotes, a @@ -2602,6 +2777,10 @@ If the .B nullglob option is set, and no matches are found, the word is removed. +If the +.B failglob +shell option is set, and no matches are found, an error message +is printed and the command is not executed. If the shell option .B nocaseglob is enabled, the match is performed without regard to the case @@ -2626,6 +2805,7 @@ below under for a description of the .BR nocaseglob , .BR nullglob , +.BR failglob , and .B dotglob shell options. @@ -2723,7 +2903,7 @@ and .BR ] , \fIcharacter classes\fP can be specified using the syntax \fB[:\fP\fIclass\fP\fB:]\fP, where \fIclass\fP is one of the -following classes defined in the POSIX.2 standard: +following classes defined in the POSIX standard: .PP .RS .B @@ -2775,7 +2955,7 @@ Matches zero or more occurrences of the given patterns Matches one or more occurrences of the given patterns .TP \fB@(\fP\^\fIpattern-list\^\fP\fB)\fP -Matches exactly one of the given patterns +Matches one of the given patterns .TP \fB!(\fP\^\fIpattern-list\^\fP\fB)\fP Matches anything except one of the given patterns @@ -2786,7 +2966,7 @@ Matches anything except one of the given patterns After the preceding expansions, all unquoted occurrences of the characters .BR \e , -.BR ' , +.BR \(aq , and \^\f3"\fP\^ that did not result from one of the above expansions are removed. .SH REDIRECTION @@ -2872,6 +3052,10 @@ a UDP connection to the corresponding socket. .RE .PP A failure to open or create a file causes the redirection to fail. +.PP +Redirections using file descriptors greater than 9 should be used with +care, as they may conflict with file descriptors the shell uses +internally. .SS Redirecting Input .PP Redirection of input causes the file whose name results from @@ -3123,16 +3307,18 @@ builtin commands (see .SM .B SHELL BUILTIN COMMANDS below). -The first word of each command, if unquoted, +The first word of each simple command, if unquoted, is checked to see if it has an alias. If so, that word is replaced by the text of the alias. -The alias name and the replacement text may contain any valid -shell input, including the -.I metacharacters -listed above, with the exception that the alias name may not -contain \fI=\fP. The first word of the replacement text is tested +The characters \fB/\fP, \fB$\fP, \fB`\fP, and \fB=\fP and +any of the shell \fImetacharacters\fP or quoting characters +listed above may not appear in an alias name. +The replacement text may contain any valid shell input, +including shell metacharacters. +The first word of the replacement text is tested for aliases, but a word that is identical to an alias being expanded -is not expanded a second time. This means that one may alias +is not expanded a second time. +This means that one may alias .B ls to .BR "ls \-F" , @@ -3206,7 +3392,7 @@ function become the positional parameters during its execution. The special parameter .B # -is updated to reflect the change. Positional parameter 0 +is updated to reflect the change. Special parameter 0 is unchanged. The first element of the .SM @@ -3218,19 +3404,21 @@ environment are identical between a function and its caller with the exception that the .SM .B DEBUG -trap (see the description of the +and +.B RETURN +traps (see the description of the .B trap builtin under .SM .B SHELL BUILTIN COMMANDS -below) is not inherited unless the function has been given the +below) are not inherited unless the function has been given the \fBtrace\fP attribute (see the description of the .SM .B declare builtin below) or the \fB\-o functrace\fP shell option has been enabled with the \fBset\fP builtin -(in which case all functions inherit the \fBDEBUG\fP trap). +(in which case all functions inherit the \fBDEBUG\fP and \fBRETURN\fP traps). .PP Variables local to the function may be declared with the .B local @@ -3271,6 +3459,10 @@ automatically have them defined with the option to the .B export builtin. +A function definition may be deleted using the \fB\-f\fP option to +the +.B unset +builtin. Note that shell functions and variables with the same name may result in multiple identically-named entries in the environment passed to the shell's children. @@ -3369,7 +3561,7 @@ If \fIbase#\fP is omitted, then base 10 is used. The digits greater than 9 are represented by the lowercase letters, the uppercase letters, @, and _, in that order. If \fIbase\fP is less than or equal to 36, lowercase and uppercase -letters may be used interchangably to represent numbers between 10 +letters may be used interchangeably to represent numbers between 10 and 35. .PP Operators are evaluated in order of precedence. Sub-expressions in @@ -3385,6 +3577,9 @@ If any \fIfile\fP argument to one of the primaries is of the form If the \fIfile\fP argument to one of the primaries is one of \fI/dev/stdin\fP, \fI/dev/stdout\fP, or \fI/dev/stderr\fP, file descriptor 0, 1, or 2, respectively, is checked. +.PP +Unless otherwise specified, primaries that operate on files follow symbolic +links and operate on the target of the link, rather than the link itself. .sp 1 .PD 0 .TP @@ -3478,9 +3673,11 @@ builtin below. .B \-z \fIstring\fP True if the length of \fIstring\fP is zero. .TP -.B \-n \fIstring\fP -.TP \fIstring\fP +.PD 0 +.TP +.B \-n \fIstring\fP +.PD True if the length of .I string is non-zero. @@ -3670,13 +3867,14 @@ the file creation mode mask shell variables and functions marked for export, along with variables exported for the command, passed in the environment .IP \(bu -traps caught by the shell are reset to the values the inherited -from the shell's parent, and traps ignored by the shell are ignored +traps caught by the shell are reset to the values inherited from the +shell's parent, and traps ignored by the shell are ignored .PP A command invoked in this separate environment cannot affect the shell's execution environment. .PP -Command substitution and asynchronous commands are invoked in a +Command substitution, commands grouped with parentheses, +and asynchronous commands are invoked in a subshell environment that is a duplicate of the shell environment, except that traps caught by the shell are reset to the values that the shell inherited from its parent at invocation. Builtin @@ -3790,7 +3988,7 @@ and .SM .BR SIGTSTP . .PP -Synchronous jobs started by \fBbash\fP have signal handlers +Non-builtin commands run by \fBbash\fP have signal handlers set to the values inherited by the shell from its parent. When job control is not in effect, asynchronous commands ignore @@ -3799,7 +3997,7 @@ ignore and .SM .B SIGQUIT -as well. +in addition to these inherited handlers. Commands run as a result of command substitution ignore the keyboard-generated job control signals .SM @@ -3847,9 +4045,9 @@ sends a .B SIGHUP to all jobs when an interactive login shell exits. .PP -When \fBbash\fP receives a signal for which a trap has been set while -waiting for a command to complete, the trap will not be executed until -the command completes. +If \fBbash\fP is waiting for a command to complete and receives a signal +for which a trap has been set, the trap will not be executed until +the command completes. When \fBbash\fP is waiting for an asynchronous command via the \fBwait\fP builtin, the reception of a signal for which a trap has been set will cause the \fBwait\fP builtin to return immediately with an exit status @@ -3977,6 +4175,8 @@ command), the current job is always flagged with a .BR + , and the previous job with a .BR \- . +A single % (with no accompanying job specification) also refers to the +current job. .PP Simply naming a job can be used to bring it into the foreground: @@ -4009,11 +4209,15 @@ is executed for each child that exits. .PP If an attempt to exit .B bash -is made while jobs are stopped, the shell prints a warning message. The +is made while jobs are stopped (or, if the \fBcheckjobs\fP shell option has +been enabled using the \fBshopt\fP builtin, running), the shell prints a +warning message, and, if the \fBcheckjobs\fP option is enabled, lists the +jobs and their statuses. +The .B jobs -command may then be used to inspect their status. +command may then be used to inspect their status. If a second attempt to exit is made without an intervening command, -the shell does not print another warning, and the stopped +the shell does not print another warning, and any stopped jobs are terminated. .SH PROMPTING When executing interactively, @@ -4087,13 +4291,14 @@ the username of the current user the version of \fBbash\fP (e.g., 2.00) .TP .B \eV -the release of \fBbash\fP, version + patchelvel (e.g., 2.00.0) +the release of \fBbash\fP, version + patch level (e.g., 2.00.0) .TP .B \ew -the current working directory +the current working directory, with \fB$HOME\fP abbreviated with a tilde .TP .B \eW -the basename of the current working directory +the basename of the current working directory, with \fB$HOME\fP +abbreviated with a tilde .TP .B \e! the history number of this command @@ -4334,8 +4539,8 @@ backslash .B \e" literal " .TP -.B \e' -literal ' +.B \e\(aq +literal \(aq .RE .PD .PP @@ -4383,7 +4588,7 @@ be used to indicate a macro definition. Unquoted text is assumed to be a function name. In the macro body, the backslash escapes described above are expanded. Backslash will quote any other character in the macro text, -including " and '. +including " and \(aq. .PP .B Bash allows the current readline key bindings to be displayed or modified @@ -4412,7 +4617,12 @@ file with a statement of the form Except where noted, readline variables can take the values .B On or -.BR Off . +.B Off +(without regard to case). +Unrecognized variable names are ignored. +When a variable value is read, empty or null values, "on" (case-insensitive), +and "1" are equivalent to \fBOn\fP. All other values are equivalent to +\fBOff\fP. The variables and their default values are: .PP .PD 0 @@ -4423,6 +4633,11 @@ If set to \fBnone\fP, readline never rings the bell. If set to \fBvisible\fP, readline uses a visible bell if one is available. If set to \fBaudible\fP, readline attempts to ring the terminal's bell. .TP +.B bind\-tty\-special\-chars (On) +If set to \fBOn\fP, readline attempts to bind the control characters +treated specially by the kernel's terminal driver to their readline +equivalents. +.TP .B comment\-begin (``#'') The string that is inserted when the readline .B insert\-comment @@ -4476,9 +4691,9 @@ arrow keys. If set to \fBon\fP, tilde expansion is performed when readline attempts word completion. .TP -.B history-preserve-point +.B history\-preserve\-point (Off) If set to \fBon\fP, the history code attempts to place point at the -same location on each history line retrived with \fBprevious-history\fP +same location on each history line retrieved with \fBprevious-history\fP or \fBnext-history\fP. .TP .B horizontal\-scroll\-mode (Off) @@ -4550,6 +4765,16 @@ set to words which have more than one possible completion cause the matches to be listed immediately instead of ringing the bell. .TP +.B show\-all\-if\-unmodified (Off) +This alters the default behavior of the completion functions in +a fashion similar to \fBshow\-all\-if\-ambiguous\fP. +If set to +.BR on , +words which have more than one possible completion without any +possible partial completion (the possible completions don't share +a common prefix) cause the matches to be listed immediately instead +of ringing the bell. +.TP .B visible\-stats (Off) If set to \fBOn\fP, a character denoting a file's type as reported by \fIstat\fP(2) is appended to the filename when listing possible @@ -4768,6 +4993,8 @@ With an argument insert the \fIn\fPth word from the previous command (the words in the previous command begin with word 0). A negative argument inserts the \fIn\fPth word from the end of the previous command. +Once the argument \fIn\fP is computed, the argument is extracted +as if the "!\fIn\fP" history expansion had been specified. .TP .B yank\-last\-arg (M\-.\^, M\-_\^) @@ -4776,6 +5003,8 @@ the previous history entry). With an argument, behave exactly like \fByank\-nth\-arg\fP. Successive calls to \fByank\-last\-arg\fP move back through the history list, inserting the last argument of each line in turn. +The history expansion facilities are used to extract the last argument, +as if the "!$" history expansion had been specified. .TP .B shell\-expand\-line (M\-C\-e) Expand the line as the shell does. This @@ -4925,6 +5154,11 @@ Word boundaries are the same as those used by \fBbackward\-word\fP. Kill the word behind point, using white space as a word boundary. The killed text is saved on the kill-ring. .TP +.B unix\-filename\-rubout +Kill the word behind point, using white space and the slash character +as the word boundaries. +The killed text is saved on the kill-ring. +.TP .B delete\-horizontal\-space (M\-\e) Delete all spaces and tabs around point. .TP @@ -5183,7 +5417,7 @@ of an \fIinputrc\fP file. .TP .B dump\-macros Print all of the readline key sequences bound to macros and the -strings they ouput. If a numeric argument is supplied, +strings they output. If a numeric argument is supplied, the output is formatted in such a way that it can be made part of an \fIinputrc\fP file. .TP @@ -5247,7 +5481,7 @@ special variable as delimiters. Shell quoting is honored. Each word is then expanded using brace expansion, tilde expansion, parameter and variable expansion, -command substitution, arithmetic expansion, and pathname expansion, +command substitution, and arithmetic expansion, as described above under .SM .BR EXPANSION . @@ -5260,10 +5494,14 @@ After these matches have been generated, any shell function or command specified with the \fB\-F\fP and \fB\-C\fP options is invoked. When the command or function is invoked, the .SM -.B COMP_LINE +.BR COMP_LINE , +.SM +.BR COMP_POINT , +.SM +.BR COMP_KEY , and .SM -.B COMP_POINT +.B COMP_TYPE variables are assigned values as described above under \fBShell Variables\fP. If a shell function is being invoked, the @@ -5314,13 +5552,21 @@ If the previously-applied actions do not generate any matches, and the \fB\-o dirnames\fP option was supplied to \fBcomplete\fP when the compspec was defined, directory name completion is attempted. .PP +If the \fB\-o plusdirs\fP option was supplied to \fBcomplete\fP when the +compspec was defined, directory name completion is attempted and any +matches are added to the results of the other actions. +.PP By default, if a compspec is found, whatever it generates is returned to the completion code as the full set of possible completions. The default \fBbash\fP completions are not attempted, and the readline default of filename completion is disabled. -If the \fB-o default\fP option was supplied to \fBcomplete\fP when the -compspec was defined, readline's default completion will be performed +If the \fB\-o bashdefault\fP option was supplied to \fBcomplete\fP when +the compspec was defined, the \fBbash\fP default completions are attempted if the compspec generates no matches. +If the \fB\-o default\fP option was supplied to \fBcomplete\fP when the +compspec was defined, readline's default completion will be performed +if the compspec (and, if attempted, the default \fBbash\fP completions) +generate no matches. .PP When a compspec indicates that directory name completion is desired, the programmable completion functions force readline to append a slash @@ -5472,6 +5718,12 @@ history expansion character, which is \^\fB!\fP\^ by default. Only backslash (\^\fB\e\fP\^) and single quotes can quote the history expansion character. .PP +Several characters inhibit history expansion if found immediately +following the history expansion character, even if it is unquoted: +space, tab, newline, carriage return, and \fB=\fP. +If the \fBextglob\fP shell option is enabled, \fB(\fP will also +inhibit expansion. +.PP Several shell options settable with the .B shopt builtin may be used to tailor the behavior of history expansion. @@ -5523,7 +5775,8 @@ history list. .B ! Start a history substitution, except when followed by a .BR blank , -newline, = or ( (when the \fBextglob\fP shell option is enabled using +newline, carriage return, = +or ( (when the \fBextglob\fP shell option is enabled using the \fBshopt\fP builtin). .TP .B !\fIn\fR @@ -5699,6 +5952,8 @@ section as accepting options preceded by accepts .B \-\- to signify the end of the options. +For example, the \fB:\fP, \fBtrue\fP, \fBfalse\fP, and \fBtest\fP builtins +do not accept options. .sp .5 .PD 0 .TP @@ -5765,17 +6020,18 @@ is supplied, the name and value of the alias is printed. \fBAlias\fP returns true unless a \fIname\fP is given for which no alias has been defined. .TP -\fBbg\fP [\fIjobspec\fP] -Resume the suspended job \fIjobspec\fP in the background, as if it +\fBbg\fP [\fIjobspec\fP ...] +Resume each suspended job \fIjobspec\fP in the background, as if it had been started with .BR & . -If \fIjobspec\fP is not present, the shell's notion of the -\fIcurrent job\fP is used. +If +.I jobspec +is not present, the shell's notion of the \fIcurrent job\fP is used. .B bg .I jobspec returns 0 unless run when job control is disabled or, when run with -job control enabled, if \fIjobspec\fP was not found or started without -job control. +job control enabled, any specified \fIjobspec\fP was not found +or was started without job control. .TP \fBbind\fP [\fB\-m\fP \fIkeymap\fP] [\fB\-lpsvPSV\fP] .PD 0 @@ -5828,13 +6084,6 @@ that they can be re-read. .B \-P List current \fBreadline\fP function names and bindings. .TP -.B \-v -Display \fBreadline\fP variable names and values in such a way that they -can be re-read. -.TP -.B \-V -List current \fBreadline\fP variable names and values. -.TP .B \-s Display \fBreadline\fP key sequences bound to macros and the strings they output in such a way that they can be re-read. @@ -5843,6 +6092,13 @@ they output in such a way that they can be re-read. Display \fBreadline\fP key sequences bound to macros and the strings they output. .TP +.B \-v +Display \fBreadline\fP variable names and values in such a way that they +can be re-read. +.TP +.B \-V +List current \fBreadline\fP variable names and values. +.TP .B \-f \fIfilename\fP Read key bindings from \fIfilename\fP. .TP @@ -5931,6 +6187,10 @@ option forces symbolic links to be followed. An argument of is equivalent to .SM .BR $OLDPWD . +If a non-empty directory name from \fBCDPATH\fP is used, or if +\fB\-\fP is the first argument, and the directory change is +successful, the absolute pathname of the new working directory is +written to the standard output. The return value is true if the directory was successfully changed; false otherwise. .TP @@ -6011,9 +6271,9 @@ will be displayed. The return value is true unless an invalid option is supplied, or no matches were generated. .TP -\fBcomplete\fP [\fB\-abcdefgjksuv\fP] [\fB\-o\fP \fIcomp-option\fP] [\fB\-A\fP \fIaction\fP] [\fB\-G\fP \fIglobpat\fP] [\fB\-W\fP \fIwordlist\fP] [\fB\-P\fP \fIprefix\fP] [\fB\-S\fP \fIsuffix\fP] +\fBcomplete\fP [\fB\-abcdefgjksuv\fP] [\fB\-o\fP \fIcomp-option\fP] [\fB\-A\fP \fIaction\fP] [\fB\-G\fP \fIglobpat\fP] [\fB\-W\fP \fIwordlist\fP] [\fB\-F\fP \fIfunction\fP] [\fB\-C\fP \fIcommand\fP] .br -[\fB\-X\fP \fIfilterpat\fP] [\fB\-F\fP \fIfunction\fP] [\fB\-C\fP \fIcommand\fP] \fIname\fP [\fIname ...\fP] +[\fB\-X\fP \fIfilterpat\fP] [\fB\-P\fP \fIprefix\fP] [\fB\-S\fP \fIsuffix\fP] \fIname\fP [\fIname ...\fP] .PD 0 .TP \fBcomplete\fP \fB\-pr\fP [\fIname\fP ...] @@ -6044,6 +6304,10 @@ beyond the simple generation of completions. \fIcomp-option\fP may be one of: .RS .TP 8 +.B bashdefault +Perform the rest of the default \fBbash\fP completions if the compspec +generates no matches. +.TP 8 .B default Use readline's default filename completion if the compspec generates no matches. @@ -6059,6 +6323,11 @@ suppressing trailing spaces). Intended to be used with shell functions. .B nospace Tell readline not to append a space (the default) to words completed at the end of the line. +.TP 8 +.B plusdirs +After any matches defined by the compspec are generated, +directory name completion is attempted and any +matches are added to the results of the other actions. .RE .TP 8 \fB\-A\fP \fIaction\fP @@ -6261,7 +6530,8 @@ by subsequent assignment statements or unset. .TP .B \-t Give each \fIname\fP the \fItrace\fP attribute. -Traced functions inherit the \fBDEBUG\fP trap from the calling shell. +Traced functions inherit the \fBDEBUG\fP and \fBRETURN\fP traps from +the calling shell. The trace attribute has no special meaning for variables. .TP .B \-x @@ -6269,8 +6539,11 @@ Mark \fIname\fPs for export to subsequent commands via the environment. .PD .PP Using `+' instead of `\-' -turns off the attribute instead, with the exception that \fB+a\fP -may not be used to destroy an array variable. When used in a function, +turns off the attribute instead, +with the exceptions that \fB+a\fP +may not be used to destroy an array variable and \fB+r\fB will not +remove the readonly attribute. +When used in a function, makes each \fIname\fP local, as with the .B local @@ -6291,7 +6564,7 @@ an attempt is made to turn off array status for an array variable, or an attempt is made to display a non-existent function with \fB\-f\fP. .RE .TP -.B dirs [\fB\-clpv\fP] [+\fIn\fP] [\-\fIn\fP] +.B dirs [+\fIn\fP] [\-\fIn\fP] [\fB\-cplv\fP] Without options, displays the list of currently remembered directories. The default display is on a single line with directory names separated by spaces. @@ -6339,6 +6612,10 @@ of the directory stack. Without options, each .I jobspec is removed from the table of active jobs. +If +.I jobspec +is not present, and neither \fB\-a\fB nor \fB\-r\fP is supplied, +the shell's notion of the \fIcurrent job\fP is used. If the \fB\-h\fP option is given, each .I jobspec is not removed from the table, but is marked so that @@ -6380,9 +6657,7 @@ The \fBxpg_echo\fP shell option may be used to dynamically determine whether or not \fBecho\fP expands these escape characters by default. .B echo -does not interpret -.B \-\- -to mean the end of options. +does not interpret \fB\-\-\fP to mean the end of options. .B echo interprets the following escape sequences: .RS @@ -6422,17 +6697,13 @@ backslash the eight-bit character whose value is the octal value \fInnn\fP (zero to three octal digits) .TP -.B \e\fInnn\fP -the eight-bit character whose value is the octal value \fInnn\fP -(one to three octal digits) -.TP .B \ex\fIHH\fP the eight-bit character whose value is the hexadecimal value \fIHH\fP (one or two hex digits) .PD .RE .TP -\fBenable\fP [\fB\-adnps\fP] [\fB\-f\fP \fIfilename\fP] [\fIname\fP ...] +\fBenable\fP [\fB\-a\fP] [\fB\-dnps\fP] [\fB\-f\fP \fIfilename\fP] [\fIname\fP ...] Enable and disable builtin shell commands. Disabling a builtin allows a disk command which has the same name as a shell builtin to be executed without specifying a full pathname, @@ -6493,7 +6764,7 @@ become the arguments to \fIcommand\fP. If the .B \-l option is supplied, -the shell places a dash at the beginning of the zeroth arg passed to +the shell places a dash at the beginning of the zeroth argument passed to .IR command . This is what .IR login (1) @@ -6551,8 +6822,8 @@ option is supplied, a list of all names that are exported in this shell is printed. The .B \-n -option causes the export property to be removed from the -named variables. +option causes the export property to be removed from each +\fIname\fP. If a variable name is followed by =\fIword\fP, the value of the variable is set to \fIword\fP. .B export @@ -6564,7 +6835,7 @@ is supplied with a .I name that is not a function. .TP -\fBfc\fP [\fB\-e\fP \fIename\fP] [\fB\-nlr\fP] [\fIfirst\fP] [\fIlast\fP] +\fBfc\fP [\fB\-e\fP \fIename\fP] [\fB\-lnr\fP] [\fIfirst\fP] [\fIlast\fP] .PD 0 .TP \fBfc\fP \fB\-s\fP [\fIpat\fP=\fIrep\fP] [\fIcmd\fP] @@ -6844,7 +7115,13 @@ have been modified. An argument of .I n lists only the last .I n -lines. If \fIfilename\fP is supplied, it is used as the +lines. +If the shell variable \fBHISTTIMEFORMAT\fP is set and not null, +it is used as a format string for \fIstrftime\fP(3) to display +the time stamp associated with each displayed history entry. +No intervening blank is printed between the formatted time stamp +and the history line. +If \fIfilename\fP is supplied, it is used as the name of the history file; if not, the value of .SM .B HISTFILE @@ -6891,6 +7168,8 @@ history list is removed before the are added. .PD .PP +If the \fBHISTTIMEFORMAT\fP is set, the time stamp information +associated with each history entry is written to the history file. The return value is 0 unless an invalid option is encountered, an error occurs while reading or writing the history file, an invalid \fIoffset\fP is supplied as an argument to \fB\-d\fP, or the @@ -6965,18 +7244,15 @@ to the processes named by or .IR jobspec . .I sigspec -is either a signal name such as +is either a case-insensitive signal name such as .SM .B SIGKILL -or a signal number; -.I signum -is a signal number. If -.I sigspec -is a signal name, the name may be -given with or without the +(with or without the .SM .B SIG -prefix. +prefix) or a signal number; +.I signum +is a signal number. If .I sigspec is not present, then @@ -7045,6 +7321,10 @@ Arguments, if supplied, have the following meanings: .RS .PD 0 .TP +.B \-n +Suppresses the normal change of directory when removing directories +from the stack, so that only the stack is manipulated. +.TP \fB+\fP\fIn\fP Removes the \fIn\fPth entry counting from the left of the list shown by @@ -7068,10 +7348,6 @@ removes the last directory, .if n ``popd -1'' .if t \f(CWpopd -1\fP the next to last. -.TP -.B \-n -Suppresses the normal change of directory when removing directories -from the stack, so that only the stack is manipulated. .PD .PP If the @@ -7085,7 +7361,7 @@ is empty, a non-existent directory stack entry is specified, or the directory change fails. .RE .TP -\fBprintf\fP \fIformat\fP [\fIarguments\fP] +\fBprintf\fP [\fB\-v\fP \fIvar\fP] \fIformat\fP [\fIarguments\fP] Write the formatted \fIarguments\fP to the standard output under the control of the \fIformat\fP. The \fIformat\fP is a character string which contains three types of objects: @@ -7095,19 +7371,25 @@ format specifications, each of which causes printing of the next successive \fIargument\fP. In addition to the standard \fIprintf\fP(1) formats, \fB%b\fP causes \fBprintf\fP to expand backslash escape sequences in the corresponding -\fIargument\fP, and \fB%q\fP causes \fBprintf\fP to output the corresponding +\fIargument\fP (except that \fB\ec\fP terminates output, backslashes in +\fB\e\(aq\fP, \fB\e"\fP, and \fB\e?\fP are not removed, and octal escapes +beginning with \fB\e0\fP may contain up to four digits), +and \fB%q\fP causes \fBprintf\fP to output the corresponding \fIargument\fP in a format that can be reused as shell input. .sp 1 +The \fB\-v\fP option causes the output to be assigned to the variable +\fIvar\fP rather than being printed to the standard output. +.sp 1 The \fIformat\fP is reused as necessary to consume all of the \fIarguments\fP. If the \fIformat\fP requires more \fIarguments\fP than are supplied, the extra format specifications behave as if a zero value or null string, as appropriate, had been supplied. The return value is zero on success, non-zero on failure. .TP -\fBpushd\fP [\fB\-n\fP] [\fIdir\fP] +\fBpushd\fP [\fB\-n\fP] [+\fIn\fP] [\-\fIn\fP] .PD 0 .TP -\fBpushd\fP [\fB\-n\fP] [+\fIn\fP] [\-\fIn\fP] +\fBpushd\fP [\fB\-n\fP] [\fIdir\fP] .PD Adds a directory to the top of the directory stack, or rotates the stack, making the new top of the stack the current working @@ -7117,6 +7399,10 @@ Arguments, if supplied, have the following meanings: .RS .PD 0 .TP +.B \-n +Suppresses the normal change of directory when adding directories +to the stack, so that only the stack is manipulated. +.TP \fB+\fP\fIn\fP Rotates the stack so that the \fIn\fPth directory (counting from the left of the list shown by @@ -7130,10 +7416,6 @@ Rotates the stack so that the \fIn\fPth directory .BR dirs , starting with zero) is at the top. .TP -.B \-n -Suppresses the normal change of directory when adding directories -to the stack, so that only the stack is manipulated. -.TP .I dir Adds .I dir @@ -7174,7 +7456,7 @@ The return status is 0 unless an error occurs while reading the name of the current directory or an invalid option is supplied. .TP -\fBread\fP [\fB\-ers\fP] [\fB\-u\fP \fIfd\fP] [\fB\-t\fP \fItimeout\fP] [\fB\-a\fP \fIaname\fP] [\fB\-p\fP \fIprompt\fP] [\fB\-n\fP \fInchars\fP] [\fB\-d\fP \fIdelim\fP] [\fIname\fP ...] +\fBread\fP [\fB\-ers\fP] [\fB\-a\fP \fIaname\fP] [\fB\-d\fP \fIdelim\fP] [\fB\-n\fP \fInchars\fP] [\fB\-p\fP \fIprompt\fP] [\fB\-t\fP \fItimeout\fP] [\fB\-u\fP \fIfd\fP] [\fIname\fP ...] One line is read from the standard input, or from the file descriptor \fIfd\fP supplied as an argument to the \fB\-u\fP option, and the first word is assigned to the first @@ -7243,7 +7525,7 @@ input is not read within \fItimeout\fP seconds. This option has no effect if \fBread\fP is not reading input from the terminal or a pipe. .TP -.B \-u \fIfd\FP +.B \-u \fIfd\fP Read input from file descriptor \fIfd\fP. .PD .PP @@ -7310,9 +7592,16 @@ the return status is false. Any command associated with the \fBRETURN\fP trap is executed before execution resumes after the function or script. .TP -\fBset\fP [\fB\-\-abefhkmnptuvxBCHP\fP] [\fB\-o\fP \fIoption\fP] [\fIarg\fP ...] +\fBset\fP [\fB\-\-abefhkmnptuvxBCEHPT\fP] [\fB\-o\fP \fIoption\fP] [\fIarg\fP ...] +.PD 0 +.TP +\fBset\fP [\fB+abefhkmnptuvxBCEHPT\fP] [\fB+o\fP \fIoption\fP] [\fIarg\fP ...] +.PD Without options, the name and value of each shell variable are displayed -in a format that can be reused as input. +in a format that can be reused as input +for setting or resetting the currently-set variables. +Read-only variables cannot be reset. +In \fIposix mode\fP, only shell variables are listed. The output is sorted according to the current locale. When options are specified, they set or unset shell attributes. Any arguments remaining after the options are processed are treated @@ -7326,8 +7615,8 @@ Options, if specified, have the following meanings: .PD 0 .TP 8 .B \-a -Automatically mark variables and functions which are modified or created -for export to the environment of subsequent commands. +Automatically mark variables and functions which are modified or +created for export to the environment of subsequent commands. .TP 8 .B \-b Report the status of terminated background jobs @@ -7346,12 +7635,14 @@ or .B until keyword, part of the test in an -.I if +.B if statement, part of a .B && or .B \(bv\(bv -list, or if the command's return value is +list, +any command in a pipeline but the last, +or if the command's return value is being inverted via .BR ! . A trap on \fBERR\fP, if set, is executed before the shell exits. @@ -7475,11 +7766,17 @@ Same as Same as .BR \-P . .TP 8 +.B pipefail +If set, the return value of a pipeline is the value of the last +(rightmost) command to exit with a non-zero status, or zero if all +commands in the pipeline exit successfully. +This option is disabled by default. +.TP 8 .B posix Change the behavior of .B bash where the default operation differs -from the POSIX 1003.2 standard to match the standard (\fIposix mode\fP). +from the POSIX standard to match the standard (\fIposix mode\fP). .TP 8 .B privileged Same as @@ -7593,9 +7890,11 @@ follows the logical chain of directories when performing commands which change the current directory. .TP 8 .B \-T -If set, any trap on \fBDEBUG\fP is inherited by shell functions, command -substitutions, and commands executed in a subshell environment. -The \fBDEBUG\fP trap is normally not inherited in such cases. +If set, any traps on \fBDEBUG\fP and \fBRETURN\fP are inherited by shell +functions, command substitutions, and commands executed in a +subshell environment. +The \fBDEBUG\fP and \fBRETURN\fP traps are normally not inherited +in such cases. .TP 8 .B \-\- If no arguments follow this option, then the positional parameters are @@ -7699,6 +7998,11 @@ The list of \fBshopt\fP options is: .if n .sp 1v .PD 0 .TP 8 +.B autocd +If set, a command name that is the name of a directory is executed as if +it were the argument to the \fBcd\fP command. +This option is only used by interactive shells. +.TP 8 .B cdable_vars If set, an argument to the .B cd @@ -7721,6 +8025,13 @@ If set, \fBbash\fP checks that a command found in the hash table exists before trying to execute it. If a hashed command no longer exists, a normal path search is performed. .TP 8 +.B checkjobs +If set, bash lists the status of any stopped and running jobs before +exiting an interactive shell. If any jobs are running, this causes +the exit to be deferred until a second exit is attempted without an +intervening command (see \fBJOB CONTROL\fP above). The shell always +postpones exiting if any jobs are stopped. +.TP 8 .B checkwinsize If set, \fBbash\fP checks the window size after each command and, if necessary, updates the values of @@ -7775,6 +8086,20 @@ If the command run by the \fBDEBUG\fP trap returns a value of 2, and the shell is executing in a subroutine (a shell function or a shell script executed by the \fB.\fP or \fBsource\fP builtins), a call to \fBreturn\fP is simulated. +.TP +.B 4. +\fBBASH_ARGC\fP and \fBBASH_ARGV\fP are updated as described in their +descriptions above. +.TP +.B 5. +Function tracing is enabled: command substitution, shell functions, and +subshells invoked with \fB(\fP \fIcommand\fP \fB)\fP inherit the +\fBDEBUG\fP and \fBRETURN\fP traps. +.TP +.B 6. +Error tracing is enabled: command substitution, shell functions, and +subshells invoked with \fB(\fP \fIcommand\fP \fB)\fP inherit the +\fBERROR\fP trap. .RE .TP 8 .B extglob @@ -7782,10 +8107,28 @@ If set, the extended pattern matching features described above under \fBPathname Expansion\fP are enabled. .TP 8 .B extquote -If set, \fB$\fP'\fIstring\fP' and \fB$\fP"\fIstring\fP" quoting is +If set, \fB$\fP\(aq\fIstring\fP\(aq and \fB$\fP"\fIstring\fP" quoting is performed within \fB${\fP\fIparameter\fP\fB}\fP expansions enclosed in double quotes. This option is enabled by default. .TP 8 +.B failglob +If set, patterns which fail to match filenames during pathname expansion +result in an expansion error. +.TP 8 +.B force_fignore +If set, the suffixes specified by the \fBFIGNORE\fP shell variable +cause words to be ignored when performing word completion even if +the ignored words are the only possible completions. +See +.SM +\fBSHELL VARIABLES\fP +above for a description of \fBFIGNORE\fP. +This option is enabled by default. +.TP 8 +.B gnu_errfmt +If set, shell error messages are written in the standard GNU error +message format. +.TP 8 .B histappend If set, the history list is appended to the file named by the value of the @@ -7866,6 +8209,12 @@ expansion (see .B Pathname Expansion above). .TP 8 +.B nocasematch +If set, +.B bash +matches patterns in a case\-insensitive fashion when performing matching +while executing \fBcase\fP or \fB[[\fP conditional commands. +.TP 8 .B nullglob If set, .B bash @@ -7881,8 +8230,9 @@ If set, the programmable completion facilities (see This option is enabled by default. .TP 8 .B promptvars -If set, prompt strings undergo variable and parameter expansion after -being expanded as described in +If set, prompt strings undergo +parameter expansion, command substitution, arithmetic +expansion, and quote removal after being expanded as described in .SM .B PROMPTING above. This option is enabled by default. @@ -7938,6 +8288,8 @@ Each operator and operand must be a separate argument. Expressions are composed of the primaries described above under .SM .BR "CONDITIONAL EXPRESSIONS" . +\fBtest\fP does not accept any options, nor does it accept and ignore +an argument of \fB\-\-\fP as signifying the end of options. .if t .sp 0.5 .if n .sp 1 Expressions may be combined using the following operators, listed @@ -8024,7 +8376,7 @@ using the rules listed above. Print the accumulated user and system times for the shell and for processes run from the shell. The return status is 0. .TP -\fBtrap\fP [\fB\-lp\fP] [\fIarg\fP] [\fIsigspec\fP ...] +\fBtrap\fP [\fB\-lp\fP] [[\fIarg\fP] \fIsigspec\fP ...] The command .I arg is to be read and executed when the shell receives @@ -8032,10 +8384,10 @@ signal(s) .IR sigspec . If .I arg -is absent or +is absent (and there is a single \fIsigspec\fP) or .BR \- , -all specified signals are -reset to their original values (the values they had +each specified signal is +reset to its original disposition (the value it had upon entrance to the shell). If .I arg @@ -8053,7 +8405,7 @@ If no arguments are supplied or if only .B \-p is given, .B trap -prints the list of commands associated with each signal number. +prints the list of commands associated with each signal. The .B \-l option causes the shell to print a list of signal names and @@ -8062,6 +8414,7 @@ Each .I sigspec is either a signal name defined in <\fIsignal.h\fP>, or a signal number. +Signal names are case insensitive and the SIG prefix is optional. If a .I sigspec is @@ -8083,7 +8436,7 @@ command, and before the first command executes in a shell function (see .SM .B SHELL GRAMMAR above). -Refer to the description of the \fBextglob\fP option to the +Refer to the description of the \fBextdebug\fP option to the \fBshopt\fP builtin for details of its effect on the \fBDEBUG\fP trap. If a .I sigspec @@ -8092,7 +8445,8 @@ is .BR ERR , the command .I arg -is executed whenever a simple command has a non\-zero exit status. +is executed whenever a simple command has a non\-zero exit status, +subject to the following conditions. The .SM .B ERR @@ -8111,6 +8465,7 @@ or list, or if the command's return value is being inverted via .BR ! . +These are the same conditions obeyed by the \fBerrexit\fP option. If a .I sigspec is @@ -8121,8 +8476,8 @@ the command is executed each time a shell function or a script executed with the \fB.\fP or \fBsource\fP builtins finishes executing. Signals ignored upon entry to the shell cannot be trapped or reset. -Trapped signals are reset to their original values in a child -process when it is created. +Trapped signals that are not being ignored are reset to their original +values in a child process when it is created. The return status is false if any .I sigspec is invalid; otherwise @@ -8205,7 +8560,7 @@ option suppresses shell function lookup, as with the \fBcommand\fP builtin. returns true if any of the arguments are found, false if none are found. .TP -\fBulimit\fP [\fB\-SHacdflmnpstuv\fP [\fIlimit\fP]] +\fBulimit\fP [\fB\-SHacdefilmnpqrstuvx\fP [\fIlimit\fP]] Provides control over the resources available to the shell and to processes started by it, on systems that allow such control. The \fB\-H\fP and \fB\-S\fP options specify that the hard or soft limit is @@ -8241,8 +8596,14 @@ The maximum size of core files created .B \-d The maximum size of a process's data segment .TP +.B \-e +The maximum scheduling priority ("nice") +.TP .B \-f -The maximum size of files created by the shell +The maximum size of files written by the shell and its children +.TP +.B \-i +The maximum number of pending signals .TP .B \-l The maximum size that may be locked into memory @@ -8257,6 +8618,12 @@ allow this value to be set) .B \-p The pipe size in 512-byte blocks (this may not be set) .TP +.B \-q +The maximum number of bytes in POSIX message queues +.TP +.B \-r +The maximum real-time scheduling priority +.TP .B \-s The maximum stack size .TP @@ -8268,6 +8635,9 @@ The maximum number of processes available to a single user .TP .B \-v The maximum amount of virtual memory available to the shell +.TP +.B \-x +The maximum number of file locks .PD .PP If @@ -8336,8 +8706,7 @@ refers to a shell variable. Read-only variables may not be unset. If .B \-f -is specifed, -each +is specified, each .I name refers to a shell function, and the function definition is removed. @@ -8364,9 +8733,9 @@ subsequently reset. The exit status is true unless a .I name is readonly. .TP -\fBwait\fP [\fIn\fP] -Wait for the specified process and return its termination -status. +\fBwait\fP [\fIn ...\fP] +Wait for each specified process and return its termination status. +Each .I n may be a process ID or a job specification; if a job spec is given, all processes @@ -8453,10 +8822,13 @@ turning off restricted mode with .PP These restrictions are enforced after any startup files are read. .PP -When a command that is found to be a shell script is executed (see +.ie \n(zY=1 When a command that is found to be a shell script is executed, +.el \{ When a command that is found to be a shell script is executed +(see .SM .B "COMMAND EXECUTION" above), +\} .B rbash turns off any restrictions in the shell spawned to execute the script. @@ -8507,7 +8879,7 @@ bfox@gnu.org .PP Chet Ramey, Case Western Reserve University .br -chet@po.CWRU.Edu +chet@po.cwru.edu .SH BUG REPORTS If you find a bug in .B bash, @@ -8548,7 +8920,7 @@ it provides for filing a bug report. .PP Comments and bug reports concerning this manual page should be directed to -.IR chet@po.CWRU.Edu . +.IR chet@po.cwru.edu . .SH BUGS .PP It's too big and too slow. @@ -8576,7 +8948,9 @@ a unit. .PP Commands inside of \fB$(\fP...\fB)\fP command substitution are not parsed until substitution is attempted. This will delay error -reporting until some time after the command is entered. +reporting until some time after the command is entered. For example, +unmatched parentheses, even inside shell comments, will result in +error messages while the construct is being read. .PP Array variables may not (yet) be exported. .zZ diff --git a/doc/bash.1~ b/doc/bash.1~ index 37998900a..8738a5e92 100644 --- a/doc/bash.1~ +++ b/doc/bash.1~ @@ -6,12 +6,12 @@ .\" Case Western Reserve University .\" chet@po.cwru.edu .\" -.\" Last Change: Tue Dec 26 19:01:54 EST 2006 +.\" Last Change: Fri Jan 12 16:29:22 EST 2007 .\" .\" bash_builtins, strip all but Built-Ins section .if \n(zZ=1 .ig zZ .if \n(zY=1 .ig zY -.TH BASH 1 "2006 December 26" "GNU Bash-3.2" +.TH BASH 1 "2007 January 12" "GNU Bash-3.2" .\" .\" There's some problem with having a `@' .\" in a tagged paragraph with the BSD man macros. @@ -1351,6 +1351,10 @@ This variable is available only in shell functions invoked by the programmable completion facilities (see \fBProgrammable Completion\fP below). .TP +.B COMP_KEY +The key (or final key of a key sequence) used to invoke the current +completion function. +.TP .B COMP_LINE The current command line. This variable is available only in shell functions and external @@ -1748,6 +1752,8 @@ for \fIstrftime\fP(3) to print the time stamp associated with each history entry displayed by the \fBhistory\fP builtin. If this variable is set, time stamps are written to the history file so they may be preserved across shell sessions. +This uses the history comment character to distinguish timestamps from +other history lines. .TP .B HOME The home directory of the current user; the default argument for the @@ -5493,7 +5499,10 @@ When the command or function is invoked, the .BR COMP_LINE , .SM .BR COMP_POINT , +.SM +.BR COMP_KEY , and +.SM .B COMP_TYPE variables are assigned values as described above under \fBShell Variables\fP. @@ -5604,6 +5613,13 @@ is truncated, if necessary, to contain no more than the number of lines specified by the value of .SM .BR HISTFILESIZE . +When the history file is read, +lines beginning with the history comment character followed immediately +by a digit are interpreted as timestamps for the preceding history line. +These timestamps are optionally displayed depending on the value of the +.SM +.B HISTTIMEFORMAT +variable. When an interactive shell exits, the last .SM .B $HISTSIZE @@ -5624,7 +5640,16 @@ If .SM .B HISTFILE is unset, or if the history file is unwritable, the history is -not saved. After saving the history, the history file is truncated +not saved. +If the +.SM +.HISTTIMEFORMAT +variable is set, time stamps are written to the history file, marked +with the history comment character, so +they may be preserved across shell sessions. +This uses the history comment character to distinguish timestamps from +other history lines. +After saving the history, the history file is truncated to contain no more than .SM .B HISTFILESIZE @@ -5758,6 +5783,9 @@ history expansion mechanism (see the description of .B histchars above under .BR "Shell Variables" ). +The shell uses +the history comment character to mark history timestamps when +writing the history file. .SS Event Designators .PP An event designator is a reference to a command line entry in the @@ -7162,7 +7190,11 @@ are added. .PD .PP If the \fBHISTTIMEFORMAT\fP is set, the time stamp information -associated with each history entry is written to the history file. +associated with each history entry is written to the history file, +marked with the history comment character. +When the history file is read, lines beginning with the history +comment character followed immediately by a digit are interpreted +as timestamps for the previous history line. The return value is 0 unless an invalid option is encountered, an error occurs while reading or writing the history file, an invalid \fIoffset\fP is supplied as an argument to \fB\-d\fP, or the diff --git a/doc/bash.html b/doc/bash.html index 80646b9ab..b4ba87fa1 100644 --- a/doc/bash.html +++ b/doc/bash.html @@ -11619,6 +11619,6 @@ Array variables may not (yet) be exported.
This document was created by man2html from bash.1.
-Time: 02 January 2007 10:25:26 EST +Time: 09 January 2007 09:51:43 EST diff --git a/doc/bashref.html b/doc/bashref.html index 502c6ee7a..4f15cc417 100644 --- a/doc/bashref.html +++ b/doc/bashref.html @@ -1,6 +1,6 @@ - + +

+ +

+ + + + + +
D.1 Index of Shell Builtin Commands  Index of Bash builtin commands.
D.2 Index of Shell Reserved Words  Index of Bash reserved words.
D.3 Parameter and Variable Index  Quick reference helps you find the + variable you want.
D.4 Function Index  Index of bindable Readline functions.
D.5 Concept Index  General index for concepts described in + this manual.
+

+ + +

+ + + + + + + + + + + +
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+

D.1 Index of Shell Builtin Commands

+
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- + - - - - + + + + - +
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-

Index of Shell Reserved Words

- +

D.2 Index of Shell Reserved Words

+
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- + - - - - + + + + - +
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-

Parameter and Variable Index

- +

D.3 Parameter and Variable Index

+
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- + - - - - + + + + - +
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-

Function Index

- +

D.4 Function Index

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    \n"); +# $_ = &debug("

    \n", __LINE__); +# } + elsif ($html_element eq 'body' || $html_element eq 'BLOCKQUOTE' || $html_element eq 'DD' || $html_element eq 'LI') + { + &html_push('P'); + push(@lines, &debug("

    \n", __LINE__)); + } + } + # otherwise + push(@lines, $_) unless $in_titlepage; + push(@lines, &debug("\n", __LINE__)) if ($tag eq 'center'); +} + +# finish TOC +$level = 0; +while ($level < $curlevel) { + $curlevel--; + push(@toc_lines, "\n"); +} + +print "# end of pass 1\n" if $T2H_VERBOSE; + +SetDocumentLanguage('en') unless ($T2H_LANG); +#+++############################################################################ +# # +# Stuff related to Index generation # +# # +#---############################################################################ + +sub EnterIndexEntry +{ + my $prefix = shift; + my $key = shift; + my $docu_doc = shift; + my $section = shift; + my $lines = shift; + local $_; + + warn "$ERROR Undefined index command: $_", next + unless (exists ($index_properties->{$prefix})); + $key =~ s/\s+$//; + $_ = $key; + &protect_texi; + $key = $_; + $_ = &protect_html($_); + my $html_key = substitute_style($_); + my $id; + $key = remove_style($key); + $key = remove_things($key); + $_ = $key; + &unprotect_texi; + $key = $_; + while (exists $index->{$prefix}->{$key}) {$key .= ' '}; + if ($lines->[$#lines] =~ /^$/) + { + $id = $1; + } + else + { + $id = 'IDX' . ++$idx_num; + push(@$lines, &t2h_anchor($id, '', $T2H_INVISIBLE_MARK, !$in_pre)); + } + $index->{$prefix}->{$key}->{html_key} = $html_key; + $index->{$prefix}->{$key}->{section} = $section; + $index->{$prefix}->{$key}->{href} = "$docu_doc#$id"; + print "# found ${prefix}index for '$key' with id $id\n" + if $T2H_DEBUG & $DEBUG_INDEX; +} + +sub IndexName2Prefix +{ + my $name = shift; + my $prefix; + + for $prefix (keys %$index_properties) + { + return $prefix if ($index_properties->{$prefix}->{name} eq $name); + } + return undef; +} + +sub GetIndexEntries +{ + my $normal = shift; + my $code = shift; + my ($entries, $prefix, $key) = ({}); + + for $prefix (keys %$normal) + { + for $key (keys %{$index->{$prefix}}) + { + $entries->{$key} = {%{$index->{$prefix}->{$key}}}; + } + } + + if (defined($code)) + { + for $prefix (keys %$code) + { + unless (exists $normal->{$keys}) + { + for $key (keys %{$index->{$prefix}}) + { + $entries->{$key} = {%{$index->{$prefix}->{$key}}}; + $entries->{$key}->{html_key} = "$entries->{$key}->{html_key}"; + } + } + } + } + return $entries; +} + +sub byAlpha +{ + if ($a =~ /^[A-Za-z]/) + { + if ($b =~ /^[A-Za-z]/) + { + return lc($a) cmp lc($b); + } + else + { + return 1; + } + } + elsif ($b =~ /^[A-Za-z]/) + { + return -1; + } + else + { + return lc($a) cmp lc($b); + } +} + +sub GetIndexPages +{ + my $entries = shift; + my (@Letters, $key); + my ($EntriesByLetter, $Pages, $page) = ({}, [], {}); + my @keys = sort byAlpha keys %$entries; + + for $key (@keys) + { + push @{$EntriesByLetter->{uc(substr($key,0, 1))}} , $entries->{$key}; + } + @Letters = sort byAlpha keys %$EntriesByLetter; + + $T2H_SPLIT_INDEX = 0 unless ($T2H_SPLIT); + + unless ($T2H_SPLIT_INDEX) + { + $page->{First} = $Letters[0]; + $page->{Last} = $Letters[$#Letters]; + $page->{Letters} = \@Letters; + $page->{EntriesByLetter} = $EntriesByLetter; + push @$Pages, $page; + return $Pages; + } + + if ($T2H_SPLIT_INDEX =~ /^\d+$/) + { + my $i = 0; + my ($prev_letter, $letter); + $page->{First} = $Letters[0]; + for $letter (@Letters) + { + if ($i > $T2H_SPLIT_INDEX) + { + $page->{Last} = $prev_letter; + push @$Pages, {%$page}; + $page->{Letters} = []; + $page->{EntriesByLetter} = {}; + $page->{First} = $letter; + $i=0; + } + push @{$page->{Letters}}, $letter; + $page->{EntriesByLetter}->{$letter} = [@{$EntriesByLetter->{$letter}}]; + $i += scalar(@{$EntriesByLetter->{$letter}}); + $prev_letter = $letter; + } + $page->{Last} = $Letters[$#Letters]; + push @$Pages, {%$page}; + } + return $Pages; +} + +sub GetIndexSummary +{ + my $first_page = shift; + my $Pages = shift; + my $name = shift; + my ($page, $letter, $summary, $i, $l1, $l2, $l); + + $i = 0; + $summary = '

    Jump to:   A   B @@ -14593,20 +14616,20 @@ to permit their use in free software.
    - + - + - + - +
    [ < ]
    [ < ] [ > ]   [ << ][ Up ][ Up ] [ >> ]         [Top] [Contents][Index][Index] [ ? ]
    -

    Concept Index

    - +

    D.5 Concept Index

    + +$T2H_EXAMPLE_INDENT_CELL = ''; +# same as above, only for @small +$T2H_SMALL_EXAMPLE_INDENT_CELL = ''; +# font size for @small +$T2H_SMALL_FONT_SIZE = '-1'; + +# if non-empty, and no @..heading appeared in Top node, then +# use this as header for top node/section, otherwise use value of +# @settitle or @shorttitle (in that order) +$T2H_TOP_HEADING = ''; + +# if set, use this chapter for 'Index' button, else +# use first chapter whose name matches 'index' (case insensitive) +$T2H_INDEX_CHAPTER = ''; + +# if set and $T2H_SPLIT is set, then split index pages at the next letter +# after they have more than that many entries +$T2H_SPLIT_INDEX = 100; + +# if set (e.g., to index.html) replace hrefs to this file +# (i.e., to index.html) by ./ +$T2H_HREF_DIR_INSTEAD_FILE = ''; + +######################################################################## +# Language dependencies: +# To add a new language extend T2H_WORDS hash and create $T2H_<...>_WORDS hash +# To redefine one word, simply do: +# $T2H_WORDS->{}->{} = 'whatever' in your personal init file. +# +$T2H_WORDS_EN = +{ + # titles of pages + 'ToC_Title' => 'Table of Contents', + 'Overview_Title' => 'Short Table of Contents', + 'Index_Title' => 'Index', + 'About_Title' => 'About this document', + 'Footnotes_Title' => 'Footnotes', + 'See' => 'See', + 'see' => 'see', + 'section' => 'section', +# If necessary, we could extend this as follows: +# # text for buttons +# 'Top_Button' => 'Top', +# 'ToC_Button' => 'Contents', +# 'Overview_Button' => 'Overview', +# 'Index_button' => 'Index', +# 'Back_Button' => 'Back', +# 'FastBack_Button' => 'FastBack', +# 'Prev_Button' => 'Prev', +# 'Up_Button' => 'Up', +# 'Next_Button' => 'Next', +# 'Forward_Button' =>'Forward', +# 'FastWorward_Button' => 'FastForward', +# 'First_Button' => 'First', +# 'Last_Button' => 'Last', +# 'About_Button' => 'About' +}; + +$T2H_WORD_DE = +{ + 'ToC_Title' => 'Inhaltsverzeichniss', + 'Overview_Title' => 'Kurzes Inhaltsverzeichniss', + 'Index_Title' => 'Index', + 'About_Title' => 'Über dieses Dokument', + 'Footnotes_Title' => 'Fußnoten', + 'See' => 'Siehe', + 'see' => 'siehe', + 'section' => 'Abschnitt', +}; + +$T2H_WORD_NL = +{ + 'ToC_Title' => 'Inhoudsopgave', + 'Overview_Title' => 'Korte inhoudsopgave', + 'Index_Title' => 'Index', #Not sure ;-) + 'About_Title' => 'No translation available!', #No translation available! + 'Footnotes_Title' => 'No translation available!', #No translation available! + 'See' => 'Zie', + 'see' => 'zie', + 'section' => 'sectie', +}; + +$T2H_WORD_ES = +{ + 'ToC_Title' => 'índice General', + 'Overview_Title' => 'Resumen del Contenido', + 'Index_Title' => 'Index', #Not sure ;-) + 'About_Title' => 'No translation available!', #No translation available! + 'Footnotes_Title' => 'Fußnoten', + 'See' => 'Véase', + 'see' => 'véase', + 'section' => 'sección', +}; + +$T2H_WORD_NO = +{ + 'ToC_Title' => 'Innholdsfortegnelse', + 'Overview_Title' => 'Kort innholdsfortegnelse', + 'Index_Title' => 'Indeks', #Not sure ;-) + 'About_Title' => 'No translation available!', #No translation available! + 'Footnotes_Title' => 'No translation available!', + 'See' => 'Se', + 'see' => 'se', + 'section' => 'avsnitt', +}; + +$T2H_WORD_PT = +{ + 'ToC_Title' => 'Sumário', + 'Overview_Title' => 'Breve Sumário', + 'Index_Title' => 'Índice', #Not sure ;-) + 'About_Title' => 'No translation available!', #No translation available! + 'Footnotes_Title' => 'No translation available!', + 'See' => 'Veja', + 'see' => 'veja', + 'section' => 'Seção', +}; + +$T2H_WORDS = +{ + 'en' => $T2H_WORDS_EN, + 'de' => $T2H_WORDS_DE, + 'nl' => $T2H_WORDS_NL, + 'es' => $T2H_WORDS_ES, + 'no' => $T2H_WORDS_NO, + 'pt' => $T2H_WORDS_PT +}; + +@MONTH_NAMES_EN = +( + 'January', 'February', 'March', 'April', 'May', + 'June', 'July', 'August', 'September', 'October', + 'November', 'December' +); + +@MONTH_NAMES_DE = +( + 'Januar', 'Februar', 'März', 'April', 'Mai', + 'Juni', 'Juli', 'August', 'September', 'Oktober', + 'November', 'Dezember' +); + +@MONTH_NAMES_NL = +( + 'Januari', 'Februari', 'Maart', 'April', 'Mei', + 'Juni', 'Juli', 'Augustus', 'September', 'Oktober', + 'November', 'December' +); + +@MONTH_NAMES_ES = +( + 'enero', 'febrero', 'marzo', 'abril', 'mayo', + 'junio', 'julio', 'agosto', 'septiembre', 'octubre', + 'noviembre', 'diciembre' +); + +@MONTH_NAMES_NO = +( + + 'januar', 'februar', 'mars', 'april', 'mai', + 'juni', 'juli', 'august', 'september', 'oktober', + 'november', 'desember' +); + +@MONTH_NAMES_PT = +( + 'Janeiro', 'Fevereiro', 'Março', 'Abril', 'Maio', + 'Junho', 'Julho', 'Agosto', 'Setembro', 'Outubro', + 'Novembro', 'Dezembro' +); + + +$MONTH_NAMES = +{ + 'en' => \@MONTH_NAMES_EN, + 'de' => \@MONTH_NAMES_DE, + 'es' => \@MONTH_NAMES_ES, + 'nl' => \@MONTH_NAMES_NL, + 'no' => \@MONTH_NAMES_NO, + 'pt' => \@MONTH_NAMES_PT +}; +######################################################################## +# Control of Page layout: +# You can make changes of the Page layout at two levels: +# 1.) For small changes, it is often enough to change the value of +# some global string/hash/array variables +# 2.) For larger changes, reimplement one of the T2H_DEFAULT_* routines, +# give them another name, and assign them to the respective +# $T2H_ variable. + +# As a general interface, the hashes T2H_HREF, T2H_NAME, T2H_NODE hold +# href, html-name, node-name of +# This -- current section (resp. html page) +# Top -- top page ($T2H_TOP_FILE) +# Contents -- Table of contents +# Overview -- Short table of contents +# Index -- Index page +# About -- page which explain "navigation buttons" +# First -- first node +# Last -- last node +# +# Whether or not the following hash values are set, depends on the context +# (all values are w.r.t. 'This' section) +# Next -- next node of texinfo +# Prev -- previous node of texinfo +# Up -- up node of texinfo +# Forward -- next node in reading order +# Back -- previous node in reading order +# FastForward -- if leave node, up and next, else next node +# FastBackward-- if leave node, up and prev, else prev node +# +# Furthermore, the following global variabels are set: +# $T2H_THISDOC{title} -- title as set by @setttile +# $T2H_THISDOC{fulltitle} -- full title as set by @title... +# $T2H_THISDOC{subtitle} -- subtitle as set by @subtitle +# $T2H_THISDOC{author} -- author as set by @author +# +# and pointer to arrays of lines which need to be printed by t2h_print_lines +# $T2H_OVERVIEW -- lines of short table of contents +# $T2H_TOC -- lines of table of contents +# $T2H_TOP -- lines of Top texinfo node +# $T2H_THIS_SECTION -- lines of 'This' section + +# +# There are the following subs which control the layout: +# +$T2H_print_section = \&T2H_DEFAULT_print_section; +$T2H_print_Top_header = \&T2H_DEFAULT_print_Top_header; +$T2H_print_Top_footer = \&T2H_DEFAULT_print_Top_footer; +$T2H_print_Top = \&T2H_DEFAULT_print_Top; +$T2H_print_Toc = \&T2H_DEFAULT_print_Toc; +$T2H_print_Overview = \&T2H_DEFAULT_print_Overview; +$T2H_print_Footnotes = \&T2H_DEFAULT_print_Footnotes; +$T2H_print_About = \&T2H_DEFAULT_print_About; +$T2H_print_misc_header = \&T2H_DEFAULT_print_misc_header; +$T2H_print_misc_footer = \&T2H_DEFAULT_print_misc_footer; +$T2H_print_misc = \&T2H_DEFAULT_print_misc; +$T2H_print_chapter_header = \&T2H_DEFAULT_print_chapter_header; +$T2H_print_chapter_footer = \&T2H_DEFAULT_print_chapter_footer; +$T2H_print_page_head = \&T2H_DEFAULT_print_page_head; +$T2H_print_page_foot = \&T2H_DEFAULT_print_page_foot; +$T2H_print_head_navigation = \&T2H_DEFAULT_print_head_navigation; +$T2H_print_foot_navigation = \&T2H_DEFAULT_print_foot_navigation; +$T2H_button_icon_img = \&T2H_DEFAULT_button_icon_img; +$T2H_print_navigation = \&T2H_DEFAULT_print_navigation; +$T2H_about_body = \&T2H_DEFAULT_about_body; +$T2H_print_frame = \&T2H_DEFAULT_print_frame; +$T2H_print_toc_frame = \&T2H_DEFAULT_print_toc_frame; + +######################################################################## +# Layout for html for every sections +# +sub T2H_DEFAULT_print_section +{ + my $fh = shift; + local $T2H_BUTTONS = \@T2H_SECTION_BUTTONS; + &$T2H_print_head_navigation($fh) if $T2H_SECTION_NAVIGATION; + my $nw = t2h_print_lines($fh); + if ($T2H_SPLIT eq 'section' && $T2H_SECTION_NAVIGATION) + { + &$T2H_print_foot_navigation($fh, $nw); + } + else + { + print $fh '
    ' . "\n"; + } +} + +################################################################### +# Layout of top-page I recommend that you use @ifnothtml, @ifhtml, +# @html within the Top texinfo node to specify content of top-level +# page. +# +# If you enclose everything in @ifnothtml, then title, subtitle, +# author and overview is printed +# T2H_HREF of Next, Prev, Up, Forward, Back are not defined +# if $T2H_SPLIT then Top page is in its own html file +sub T2H_DEFAULT_print_Top_header +{ + &$T2H_print_page_head(@_) if $T2H_SPLIT; + t2h_print_label(@_); # this needs to be called, otherwise no label set + &$T2H_print_head_navigation(@_); +} +sub T2H_DEFAULT_print_Top_footer +{ + &$T2H_print_foot_navigation(@_); + &$T2H_print_page_foot(@_) if $T2H_SPLIT; +} +sub T2H_DEFAULT_print_Top +{ + my $fh = shift; + + # for redefining navigation buttons use: + # local $T2H_BUTTONS = [...]; + # as it is, 'Top', 'Contents', 'Index', 'About' are printed + local $T2H_BUTTONS = \@T2H_MISC_BUTTONS; + &$T2H_print_Top_header($fh); + if ($T2H_THIS_SECTION) + { + # if top-level node has content, then print it with extra header + print $fh "

    $T2H_NAME{Top}

    " + unless ($T2H_HAS_TOP_HEADING); + t2h_print_lines($fh, $T2H_THIS_SECTION) + } + else + { + # top-level node is fully enclosed in @ifnothtml + # print fulltitle, subtitle, author, Overview + print $fh + "
    \n

    " . + join("

    \n

    ", split(/\n/, $T2H_THISDOC{fulltitle})) . + "

    \n"; + print $fh "

    $T2H_THISDOC{subtitle}

    \n" if $T2H_THISDOC{subtitle}; + print $fh "$T2H_THISDOC{author}\n" if $T2H_THISDOC{author}; + print $fh < +
    +

    +

    Overview:

    +
    +EOT + t2h_print_lines($fh, $T2H_OVERVIEW); + print $fh "
    \n"; + } + &$T2H_print_Top_footer($fh); +} + +################################################################### +# Layout of Toc, Overview, and Footnotes pages +# By default, we use "normal" layout +# T2H_HREF of Next, Prev, Up, Forward, Back, etc are not defined +# use: local $T2H_BUTTONS = [...] to redefine navigation buttons +sub T2H_DEFAULT_print_Toc +{ + return &$T2H_print_misc(@_); +} +sub T2H_DEFAULT_print_Overview +{ + return &$T2H_print_misc(@_); +} +sub T2H_DEFAULT_print_Footnotes +{ + return &$T2H_print_misc(@_); +} +sub T2H_DEFAULT_print_About +{ + return &$T2H_print_misc(@_); +} + +sub T2H_DEFAULT_print_misc_header +{ + &$T2H_print_page_head(@_) if $T2H_SPLIT; + # this needs to be called, otherwise, no labels are set + t2h_print_label(@_); + &$T2H_print_head_navigation(@_); +} +sub T2H_DEFAULT_print_misc_footer +{ + &$T2H_print_foot_navigation(@_); + &$T2H_print_page_foot(@_) if $T2H_SPLIT; +} +sub T2H_DEFAULT_print_misc +{ + my $fh = shift; + local $T2H_BUTTONS = \@T2H_MISC_BUTTONS; + &$T2H_print_misc_header($fh); + print $fh "

    $T2H_NAME{This}

    \n"; + t2h_print_lines($fh); + &$T2H_print_misc_footer($fh); +} + +################################################################### +# chapter_header and chapter_footer are only called if +# T2H_SPLIT eq 'chapter' +# chapter_header: after print_page_header, before print_section +# chapter_footer: after print_section of last section, before print_page_footer +# +# If you want to get rid of navigation stuff after each section, +# redefine print_section such that it does not call print_navigation, +# and put print_navigation into print_chapter_header +@T2H_CHAPTER_BUTTONS = + ( + 'FastBack', 'FastForward', ' ', + ' ', ' ', ' ', ' ', + 'Top', 'Contents', 'Index', 'About', + ); + +sub T2H_DEFAULT_print_chapter_header +{ + # nothing to do there, by default + if (! $T2H_SECTION_NAVIGATION) + { + my $fh = shift; + local $T2H_BUTTONS = \@T2H_CHAPTER_BUTTONS; + &$T2H_print_navigation($fh); + print $fh "\n
    \n"; + } +} + +sub T2H_DEFAULT_print_chapter_footer +{ + local $T2H_BUTTONS = \@T2H_CHAPTER_BUTTONS; + &$T2H_print_navigation(@_); +} +################################################################### +$T2H_TODAY = &pretty_date; # like "20 September 1993" + +sub pretty_date { + local($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst); + + ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst) = localtime(time); + $year += ($year < 70) ? 2000 : 1900; + # obachman: Let's do it as the Americans do + return($MONTH_NAMES->{$T2H_LANG}[$mon] . ", " . $mday . " " . $year); +} + + +################################################################### +# Layout of standard header and footer +# + +# Set the default body text, inserted between +###$T2H_BODYTEXT = 'LANG="EN" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#800080" ALINK="#FF0000"'; +$T2H_BODYTEXT = 'LANG="' . $T2H_LANG . '" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#800080" ALINK="#FF0000"'; +# text inserted after +$T2H_AFTER_BODY_OPEN = ''; +#text inserted before +$T2H_PRE_BODY_CLOSE = ''; +# this is used in footer +$T2H_ADDRESS = "by $T2H_USER " if $T2H_USER; +$T2H_ADDRESS .= "on $T2H_TODAY"; +# this is added inside after and some META NAME stuff +# can be used for <style> <script>, <meta> tags +$T2H_EXTRA_HEAD = ''; + +sub T2H_DEFAULT_print_page_head +{ + my $fh = shift; + my $longtitle = "$T2H_THISDOC{title}: $T2H_NAME{This}"; + print $fh <<EOT; +<HTML> +$T2H_DOCTYPE +<!-- Created on $T2H_TODAY by $THISPROG --> +<!-- +$T2H_AUTHORS +--> +<HEAD> +<TITLE>$longtitle + + + + + + +$T2H_EXTRA_HEAD + + + +$T2H_AFTER_BODY_OPEN +EOT +} + +sub T2H_DEFAULT_print_page_foot +{ + my $fh = shift; + print $fh < + +This document was generated +$T2H_ADDRESS +using texi2html +$T2H_PRE_BODY_CLOSE + + +EOT +} + +################################################################### +# Layout of navigation panel + +# if this is set, then a vertical navigation panel is used +$T2H_VERTICAL_HEAD_NAVIGATION = 0; +sub T2H_DEFAULT_print_head_navigation +{ + my $fh = shift; + if ($T2H_VERTICAL_HEAD_NAVIGATION) + { + print $fh < +
     + +
    Jump to:   A   B @@ -14868,7 +14891,7 @@ to permit their use in free software. - +
    [Top] [Contents][Index][Index] [ ? ]

    Table of Contents

    @@ -15191,23 +15214,27 @@ to permit their use in free software.
    -Index of Shell Builtin Commands +D. Indexes
    -Index of Shell Reserved Words +
    - +
    [Top] [Contents][Index][Index] [ ? ]

    Short Table of Contents

    @@ -15238,15 +15265,7 @@ to permit their use in free software.
    C. Copying This Manual
    -Index of Shell Builtin Commands -
    -Index of Shell Reserved Words -
    -Parameter and Variable Index -
    -Function Index -
    -Concept Index +D. Indexes
    @@ -15255,11 +15274,11 @@ to permit their use in free software. - +
    [Top] [Contents][Index][Index] [ ? ]

    About this document

    -This document was generated by Chet Ramey on January, 2 2007 +This document was generated by Chet Ramey on January, 11 2007 using texi2html

    @@ -15421,7 +15440,7 @@ the following structure:
    This document was generated -by Chet Ramey on January, 2 2007 +by Chet Ramey on January, 11 2007 using texi2html diff --git a/doc/bashref.texi b/doc/bashref.texi index 093c94d96..78f9c4cb2 100644 --- a/doc/bashref.texi +++ b/doc/bashref.texi @@ -111,13 +111,7 @@ reference on shell behavior. between Bash and historical versions of /bin/sh. * Copying This Manual:: Copying this manual. -* Builtin Index:: Index of Bash builtin commands. -* Reserved Word Index:: Index of Bash reserved words. -* Variable Index:: Quick reference helps you find the - variable you want. -* Function Index:: Index of bindable Readline functions. -* Concept Index:: General index for concepts described in - this manual. +* Indexes:: Various indexes for this manual. @end menu @end ifnottex @@ -4644,6 +4638,8 @@ for @var{strftime} to print the time stamp associated with each history entry displayed by the @code{history} builtin. If this variable is set, time stamps are written to the history file so they may be preserved across shell sessions. +This uses the history comment character to distinguish timestamps from +other history lines. @item HOSTFILE Contains the name of a file in the same format as @file{/etc/hosts} that @@ -7467,24 +7463,37 @@ The SVR4.2 shell behaves differently when invoked as @code{jsh} @include fdl.texi +@node Indexes +@appendix Indexes + +@menu +* Builtin Index:: Index of Bash builtin commands. +* Reserved Word Index:: Index of Bash reserved words. +* Variable Index:: Quick reference helps you find the + variable you want. +* Function Index:: Index of bindable Readline functions. +* Concept Index:: General index for concepts described in + this manual. +@end menu + @node Builtin Index -@unnumbered Index of Shell Builtin Commands +@appendixsec Index of Shell Builtin Commands @printindex bt @node Reserved Word Index -@unnumbered Index of Shell Reserved Words +@appendixsec Index of Shell Reserved Words @printindex rw @node Variable Index -@unnumbered Parameter and Variable Index +@appendixsec Parameter and Variable Index @printindex vr @node Function Index -@unnumbered Function Index +@appendixsec Function Index @printindex fn @node Concept Index -@unnumbered Concept Index +@appendixsec Concept Index @printindex cp @bye diff --git a/doc/bashref.texi.save b/doc/bashref.texi.save new file mode 100644 index 000000000..093c94d96 --- /dev/null +++ b/doc/bashref.texi.save @@ -0,0 +1,7490 @@ +\input texinfo.tex @c -*- texinfo -*- +@c %**start of header +@setfilename bashref.info +@settitle Bash Reference Manual +@c %**end of header + +@setchapternewpage odd + +@include version.texi + +@copying +This text is a brief description of the features that are present in +the Bash shell (version @value{VERSION}, @value{UPDATED}). + +This is Edition @value{EDITION}, last updated @value{UPDATED}, +of @cite{The GNU Bash Reference Manual}, +for @code{Bash}, Version @value{VERSION}. + +Copyright @copyright{} 1988-2005 Free Software Foundation, Inc. + +Permission is granted to make and distribute verbatim copies of +this manual provided the copyright notice and this permission notice +are preserved on all copies. + +@quotation +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.2 or +any later version published by the Free Software Foundation; with no +Invariant Sections, with the Front-Cover texts being ``A GNU Manual,'' +and with the Back-Cover Texts as in (a) below. A copy of the license is +included in the section entitled ``GNU Free Documentation License.'' + +(a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify +this GNU Manual, like GNU software. Copies published by the Free +Software Foundation raise funds for GNU development.'' +@end quotation +@end copying + +@defcodeindex bt +@defcodeindex rw +@set BashFeatures + +@dircategory Basics +@direntry +* Bash: (bash). The GNU Bourne-Again SHell. +@end direntry + +@finalout + +@titlepage +@title Bash Reference Manual +@subtitle Reference Documentation for Bash +@subtitle Edition @value{EDITION}, for @code{Bash} Version @value{VERSION}. +@subtitle @value{UPDATED-MONTH} +@author Chet Ramey, Case Western Reserve University +@author Brian Fox, Free Software Foundation + +@page +@vskip 0pt plus 1filll +@insertcopying + +@sp 1 +Published by the Free Software Foundation @* +59 Temple Place, Suite 330, @* +Boston, MA 02111-1307 @* +USA @* + +@end titlepage + +@contents + +@ifnottex +@node Top, Introduction, (dir), (dir) +@top Bash Features + +This text is a brief description of the features that are present in +the Bash shell (version @value{VERSION}, @value{UPDATED}). + +This is Edition @value{EDITION}, last updated @value{UPDATED}, +of @cite{The GNU Bash Reference Manual}, +for @code{Bash}, Version @value{VERSION}. + +Bash contains features that appear in other popular shells, and some +features that only appear in Bash. Some of the shells that Bash has +borrowed concepts from are the Bourne Shell (@file{sh}), the Korn Shell +(@file{ksh}), and the C-shell (@file{csh} and its successor, +@file{tcsh}). The following menu breaks the features up into +categories based upon which one of these other shells inspired the +feature. + +This manual is meant as a brief introduction to features found in +Bash. The Bash manual page should be used as the definitive +reference on shell behavior. + +@menu +* Introduction:: An introduction to the shell. +* Definitions:: Some definitions used in the rest of this + manual. +* Basic Shell Features:: The shell "building blocks". +* Shell Builtin Commands:: Commands that are a part of the shell. +* Shell Variables:: Variables used or set by Bash. +* Bash Features:: Features found only in Bash. +* Job Control:: What job control is and how Bash allows you + to use it. +* Using History Interactively:: Command History Expansion +* Command Line Editing:: Chapter describing the command line + editing features. +* Installing Bash:: How to build and install Bash on your system. +* Reporting Bugs:: How to report bugs in Bash. +* Major Differences From The Bourne Shell:: A terse list of the differences + between Bash and historical + versions of /bin/sh. +* Copying This Manual:: Copying this manual. +* Builtin Index:: Index of Bash builtin commands. +* Reserved Word Index:: Index of Bash reserved words. +* Variable Index:: Quick reference helps you find the + variable you want. +* Function Index:: Index of bindable Readline functions. +* Concept Index:: General index for concepts described in + this manual. +@end menu +@end ifnottex + +@node Introduction +@chapter Introduction +@menu +* What is Bash?:: A short description of Bash. +* What is a shell?:: A brief introduction to shells. +@end menu + +@node What is Bash? +@section What is Bash? + +Bash is the shell, or command language interpreter, +for the @sc{gnu} operating system. +The name is an acronym for the @samp{Bourne-Again SHell}, +a pun on Stephen Bourne, the author of the direct ancestor of +the current Unix shell @code{sh}, +which appeared in the Seventh Edition Bell Labs Research version +of Unix. + +Bash is largely compatible with @code{sh} and incorporates useful +features from the Korn shell @code{ksh} and the C shell @code{csh}. +It is intended to be a conformant implementation of the @sc{ieee} +@sc{posix} Shell and Tools portion of the @sc{ieee} @sc{posix} +specification (@sc{ieee} Standard 1003.1). +It offers functional improvements over @code{sh} for both interactive and +programming use. + +While the @sc{gnu} operating system provides other shells, including +a version of @code{csh}, Bash is the default shell. +Like other @sc{gnu} software, Bash is quite portable. It currently runs +on nearly every version of Unix and a few other operating systems @minus{} +independently-supported ports exist for @sc{ms-dos}, @sc{os/2}, +and Windows platforms. + +@node What is a shell? +@section What is a shell? + +At its base, a shell is simply a macro processor that executes +commands. The term macro processor means functionality where text +and symbols are expanded to create larger expressions. + +A Unix shell is both a command interpreter and a programming +language. As a command interpreter, the shell provides the user +interface to the rich set of @sc{gnu} utilities. The programming +language features allow these utilities to be combined. +Files containing commands can be created, and become +commands themselves. These new commands have the same status as +system commands in directories such as @file{/bin}, allowing users +or groups to establish custom environments to automate their common +tasks. + +Shells may be used interactively or non-interactively. In +interactive mode, they accept input typed from the keyboard. +When executing non-interactively, shells execute commands read +from a file. + +A shell allows execution of @sc{gnu} commands, both synchronously and +asynchronously. +The shell waits for synchronous commands to complete before accepting +more input; asynchronous commands continue to execute in parallel +with the shell while it reads and executes additional commands. +The @dfn{redirection} constructs permit +fine-grained control of the input and output of those commands. +Moreover, the shell allows control over the contents of commands' +environments. + +Shells also provide a small set of built-in +commands (@dfn{builtins}) implementing functionality impossible +or inconvenient to obtain via separate utilities. +For example, @code{cd}, @code{break}, @code{continue}, and +@code{exec}) cannot be implemented outside of the shell because +they directly manipulate the shell itself. +The @code{history}, @code{getopts}, @code{kill}, or @code{pwd} +builtins, among others, could be implemented in separate utilities, +but they are more convenient to use as builtin commands. +All of the shell builtins are described in +subsequent sections. + +While executing commands is essential, most of the power (and +complexity) of shells is due to their embedded programming +languages. Like any high-level language, the shell provides +variables, flow control constructs, quoting, and functions. + +Shells offer features geared specifically for +interactive use rather than to augment the programming language. +These interactive features include job control, command line +editing, command history and aliases. Each of these features is +described in this manual. + +@node Definitions +@chapter Definitions +These definitions are used throughout the remainder of this manual. + +@table @code + +@item POSIX +@cindex POSIX +A family of open system standards based on Unix. Bash +is primarily concerned with the Shell and Utilities portion of the +@sc{posix} 1003.1 standard. + +@item blank +A space or tab character. + +@item builtin +@cindex builtin +A command that is implemented internally by the shell itself, rather +than by an executable program somewhere in the file system. + +@item control operator +@cindex control operator +A @code{word} that performs a control function. It is a @code{newline} +or one of the following: +@samp{||}, @samp{&&}, @samp{&}, @samp{;}, @samp{;;}, +@samp{|}, @samp{(}, or @samp{)}. + +@item exit status +@cindex exit status +The value returned by a command to its caller. The value is restricted +to eight bits, so the maximum value is 255. + +@item field +@cindex field +A unit of text that is the result of one of the shell expansions. After +expansion, when executing a command, the resulting fields are used as +the command name and arguments. + +@item filename +@cindex filename +A string of characters used to identify a file. + +@item job +@cindex job +A set of processes comprising a pipeline, and any processes descended +from it, that are all in the same process group. + +@item job control +@cindex job control +A mechanism by which users can selectively stop (suspend) and restart +(resume) execution of processes. + +@item metacharacter +@cindex metacharacter +A character that, when unquoted, separates words. A metacharacter is +a @code{blank} or one of the following characters: +@samp{|}, @samp{&}, @samp{;}, @samp{(}, @samp{)}, @samp{<}, or +@samp{>}. + +@item name +@cindex name +@cindex identifier +A @code{word} consisting solely of letters, numbers, and underscores, +and beginning with a letter or underscore. @code{Name}s are used as +shell variable and function names. +Also referred to as an @code{identifier}. + +@item operator +@cindex operator, shell +A @code{control operator} or a @code{redirection operator}. +@xref{Redirections}, for a list of redirection operators. + +@item process group +@cindex process group +A collection of related processes each having the same process +group @sc{id}. + +@item process group ID +@cindex process group ID +A unique identifier that represents a @code{process group} +during its lifetime. + +@item reserved word +@cindex reserved word +A @code{word} that has a special meaning to the shell. Most reserved +words introduce shell flow control constructs, such as @code{for} and +@code{while}. + +@item return status +@cindex return status +A synonym for @code{exit status}. + +@item signal +@cindex signal +A mechanism by which a process may be notified by the kernel +of an event occurring in the system. + +@item special builtin +@cindex special builtin +A shell builtin command that has been classified as special by the +@sc{posix} standard. + +@item token +@cindex token +A sequence of characters considered a single unit by the shell. It is +either a @code{word} or an @code{operator}. + +@item word +@cindex word +A @code{token} that is not an @code{operator}. +@end table + +@node Basic Shell Features +@chapter Basic Shell Features +@cindex Bourne shell + +Bash is an acronym for @samp{Bourne-Again SHell}. +The Bourne shell is +the traditional Unix shell originally written by Stephen Bourne. +All of the Bourne shell builtin commands are available in Bash, +The rules for evaluation and quoting are taken from the @sc{posix} +specification for the `standard' Unix shell. + +This chapter briefly summarizes the shell's `building blocks': +commands, control structures, shell functions, shell @i{parameters}, +shell expansions, +@i{redirections}, which are a way to direct input and output from +and to named files, and how the shell executes commands. + +@menu +* Shell Syntax:: What your input means to the shell. +* Shell Commands:: The types of commands you can use. +* Shell Functions:: Grouping commands by name. +* Shell Parameters:: How the shell stores values. +* Shell Expansions:: How Bash expands parameters and the various + expansions available. +* Redirections:: A way to control where input and output go. +* Executing Commands:: What happens when you run a command. +* Shell Scripts:: Executing files of shell commands. +@end menu + +@node Shell Syntax +@section Shell Syntax +@menu +* Shell Operation:: The basic operation of the shell. +* Quoting:: How to remove the special meaning from characters. +* Comments:: How to specify comments. +@end menu + +When the shell reads input, it proceeds through a +sequence of operations. If the input indicates the beginning of a +comment, the shell ignores the comment symbol (@samp{#}), and the rest +of that line. + +Otherwise, roughly speaking, the shell reads its input and +divides the input into words and operators, employing the quoting rules +to select which meanings to assign various words and characters. + +The shell then parses these tokens into commands and other constructs, +removes the special meaning of certain words or characters, expands +others, redirects input and output as needed, executes the specified +command, waits for the command's exit status, and makes that exit status +available for further inspection or processing. + +@node Shell Operation +@subsection Shell Operation + +The following is a brief description of the shell's operation when it +reads and executes a command. Basically, the shell does the +following: + +@enumerate +@item +Reads its input from a file (@pxref{Shell Scripts}), from a string +supplied as an argument to the @option{-c} invocation option +(@pxref{Invoking Bash}), or from the user's terminal. + +@item +Breaks the input into words and operators, obeying the quoting rules +described in @ref{Quoting}. These tokens are separated by +@code{metacharacters}. Alias expansion is performed by this step +(@pxref{Aliases}). + +@item +Parses the tokens into simple and compound commands +(@pxref{Shell Commands}). + +@item +Performs the various shell expansions (@pxref{Shell Expansions}), breaking +the expanded tokens into lists of filenames (@pxref{Filename Expansion}) +and commands and arguments. + +@item +Performs any necessary redirections (@pxref{Redirections}) and removes +the redirection operators and their operands from the argument list. + +@item +Executes the command (@pxref{Executing Commands}). + +@item +Optionally waits for the command to complete and collects its exit +status (@pxref{Exit Status}). + +@end enumerate + +@node Quoting +@subsection Quoting +@cindex quoting +@menu +* Escape Character:: How to remove the special meaning from a single + character. +* Single Quotes:: How to inhibit all interpretation of a sequence + of characters. +* Double Quotes:: How to suppress most of the interpretation of a + sequence of characters. +* ANSI-C Quoting:: How to expand ANSI-C sequences in quoted strings. +* Locale Translation:: How to translate strings into different languages. +@end menu + +Quoting is used to remove the special meaning of certain +characters or words to the shell. Quoting can be used to +disable special treatment for special characters, to prevent +reserved words from being recognized as such, and to prevent +parameter expansion. + +Each of the shell metacharacters (@pxref{Definitions}) +has special meaning to the shell and must be quoted if it is to +represent itself. +When the command history expansion facilities are being used +(@pxref{History Interaction}), the +@var{history expansion} character, usually @samp{!}, must be quoted +to prevent history expansion. @xref{Bash History Facilities}, for +more details concerning history expansion. + +There are three quoting mechanisms: the +@var{escape character}, single quotes, and double quotes. + +@node Escape Character +@subsubsection Escape Character +A non-quoted backslash @samp{\} is the Bash escape character. +It preserves the literal value of the next character that follows, +with the exception of @code{newline}. If a @code{\newline} pair +appears, and the backslash itself is not quoted, the @code{\newline} +is treated as a line continuation (that is, it is removed from +the input stream and effectively ignored). + +@node Single Quotes +@subsubsection Single Quotes + +Enclosing characters in single quotes (@samp{'}) preserves the literal value +of each character within the quotes. A single quote may not occur +between single quotes, even when preceded by a backslash. + +@node Double Quotes +@subsubsection Double Quotes + +Enclosing characters in double quotes (@samp{"}) preserves the literal value +of all characters within the quotes, with the exception of +@samp{$}, @samp{`}, @samp{\}, +and, when history expansion is enabled, @samp{!}. +The characters @samp{$} and @samp{`} +retain their special meaning within double quotes (@pxref{Shell Expansions}). +The backslash retains its special meaning only when followed by one of +the following characters: +@samp{$}, @samp{`}, @samp{"}, @samp{\}, or @code{newline}. +Within double quotes, backslashes that are followed by one of these +characters are removed. Backslashes preceding characters without a +special meaning are left unmodified. +A double quote may be quoted within double quotes by preceding it with +a backslash. +If enabled, history expansion will be performed unless an @samp{!} +appearing in double quotes is escaped using a backslash. +The backslash preceding the @samp{!} is not removed. + +The special parameters @samp{*} and @samp{@@} have special meaning +when in double quotes (@pxref{Shell Parameter Expansion}). + +@node ANSI-C Quoting +@subsubsection ANSI-C Quoting +@cindex quoting, ANSI + +Words of the form @code{$'@var{string}'} are treated specially. The +word expands to @var{string}, with backslash-escaped characters replaced +as specified by the ANSI C standard. Backslash escape sequences, if +present, are decoded as follows: + +@table @code +@item \a +alert (bell) +@item \b +backspace +@item \e +an escape character (not ANSI C) +@item \f +form feed +@item \n +newline +@item \r +carriage return +@item \t +horizontal tab +@item \v +vertical tab +@item \\ +backslash +@item \' +single quote +@item \@var{nnn} +the eight-bit character whose value is the octal value @var{nnn} +(one to three digits) +@item \x@var{HH} +the eight-bit character whose value is the hexadecimal value @var{HH} +(one or two hex digits) +@item \c@var{x} +a control-@var{x} character +@end table + +@noindent +The expanded result is single-quoted, as if the dollar sign had not +been present. + +@node Locale Translation +@subsubsection Locale-Specific Translation +@cindex localization +@cindex internationalization +@cindex native languages +@cindex translation, native languages + +A double-quoted string preceded by a dollar sign (@samp{$}) will cause +the string to be translated according to the current locale. +If the current locale is @code{C} or @code{POSIX}, the dollar sign +is ignored. +If the string is translated and replaced, the replacement is +double-quoted. + +@vindex LC_MESSAGES +@vindex TEXTDOMAIN +@vindex TEXTDOMAINDIR +Some systems use the message catalog selected by the @env{LC_MESSAGES} +shell variable. Others create the name of the message catalog from the +value of the @env{TEXTDOMAIN} shell variable, possibly adding a +suffix of @samp{.mo}. If you use the @env{TEXTDOMAIN} variable, you +may need to set the @env{TEXTDOMAINDIR} variable to the location of +the message catalog files. Still others use both variables in this +fashion: +@env{TEXTDOMAINDIR}/@env{LC_MESSAGES}/LC_MESSAGES/@env{TEXTDOMAIN}.mo. + +@node Comments +@subsection Comments +@cindex comments, shell + +In a non-interactive shell, or an interactive shell in which the +@code{interactive_comments} option to the @code{shopt} +builtin is enabled (@pxref{The Shopt Builtin}), +a word beginning with @samp{#} +causes that word and all remaining characters on that line to +be ignored. An interactive shell without the @code{interactive_comments} +option enabled does not allow comments. The @code{interactive_comments} +option is on by default in interactive shells. +@xref{Interactive Shells}, for a description of what makes +a shell interactive. + +@node Shell Commands +@section Shell Commands +@cindex commands, shell + +A simple shell command such as @code{echo a b c} consists of the command +itself followed by arguments, separated by spaces. + +More complex shell commands are composed of simple commands arranged together +in a variety of ways: in a pipeline in which the output of one command +becomes the input of a second, in a loop or conditional construct, or in +some other grouping. + +@menu +* Simple Commands:: The most common type of command. +* Pipelines:: Connecting the input and output of several + commands. +* Lists:: How to execute commands sequentially. +* Compound Commands:: Shell commands for control flow. +@end menu + +@node Simple Commands +@subsection Simple Commands +@cindex commands, simple + +A simple command is the kind of command encountered most often. +It's just a sequence of words separated by @code{blank}s, terminated +by one of the shell's control operators (@pxref{Definitions}). The +first word generally specifies a command to be executed, with the +rest of the words being that command's arguments. + +The return status (@pxref{Exit Status}) of a simple command is +its exit status as provided +by the @sc{posix} 1003.1 @code{waitpid} function, or 128+@var{n} if +the command was terminated by signal @var{n}. + +@node Pipelines +@subsection Pipelines +@cindex pipeline +@cindex commands, pipelines + +A @code{pipeline} is a sequence of simple commands separated by +@samp{|}. + +@rwindex time +@rwindex ! +@cindex command timing +The format for a pipeline is +@example +[@code{time} [@code{-p}]] [@code{!}] @var{command1} [@code{|} @var{command2} @dots{}] +@end example + +@noindent +The output of each command in the pipeline is connected via a pipe +to the input of the next command. +That is, each command reads the previous command's output. + +The reserved word @code{time} causes timing statistics +to be printed for the pipeline once it finishes. +The statistics currently consist of elapsed (wall-clock) time and +user and system time consumed by the command's execution. +The @option{-p} option changes the output format to that specified +by @sc{posix}. +The @env{TIMEFORMAT} variable may be set to a format string that +specifies how the timing information should be displayed. +@xref{Bash Variables}, for a description of the available formats. +The use of @code{time} as a reserved word permits the timing of +shell builtins, shell functions, and pipelines. An external +@code{time} command cannot time these easily. + +If the pipeline is not executed asynchronously (@pxref{Lists}), the +shell waits for all commands in the pipeline to complete. + +Each command in a pipeline is executed in its own subshell +(@pxref{Command Execution Environment}). The exit +status of a pipeline is the exit status of the last command in the +pipeline, unless the @code{pipefail} option is enabled +(@pxref{The Set Builtin}). +If @code{pipefail} is enabled, the pipeline's return status is the +value of the last (rightmost) command to exit with a non-zero status, +or zero if all commands exit successfully. +If the reserved word @samp{!} precedes the pipeline, the +exit status is the logical negation of the exit status as described +above. +The shell waits for all commands in the pipeline to terminate before +returning a value. + +@node Lists +@subsection Lists of Commands +@cindex commands, lists + +A @code{list} is a sequence of one or more pipelines separated by one +of the operators @samp{;}, @samp{&}, @samp{&&}, or @samp{||}, +and optionally terminated by one of @samp{;}, @samp{&}, or a +@code{newline}. + +Of these list operators, @samp{&&} and @samp{||} +have equal precedence, followed by @samp{;} and @samp{&}, +which have equal precedence. + +A sequence of one or more newlines may appear in a @code{list} +to delimit commands, equivalent to a semicolon. + +If a command is terminated by the control operator @samp{&}, +the shell executes the command asynchronously in a subshell. +This is known as executing the command in the @var{background}. +The shell does not wait for the command to finish, and the return +status is 0 (true). +When job control is not active (@pxref{Job Control}), +the standard input for asynchronous commands, in the absence of any +explicit redirections, is redirected from @code{/dev/null}. + +Commands separated by a @samp{;} are executed sequentially; the shell +waits for each command to terminate in turn. The return status is the +exit status of the last command executed. + +The control operators @samp{&&} and @samp{||} +denote @sc{and} lists and @sc{or} lists, respectively. +An @sc{and} list has the form +@example +@var{command1} && @var{command2} +@end example + +@noindent +@var{command2} is executed if, and only if, @var{command1} +returns an exit status of zero. + +An @sc{or} list has the form +@example +@var{command1} || @var{command2} +@end example + +@noindent +@var{command2} is executed if, and only if, @var{command1} +returns a non-zero exit status. + +The return status of +@sc{and} and @sc{or} lists is the exit status of the last command +executed in the list. + +@node Compound Commands +@subsection Compound Commands +@cindex commands, compound + +@menu +* Looping Constructs:: Shell commands for iterative action. +* Conditional Constructs:: Shell commands for conditional execution. +* Command Grouping:: Ways to group commands. +@end menu + +Compound commands are the shell programming constructs. +Each construct begins with a reserved word or control operator and is +terminated by a corresponding reserved word or operator. +Any redirections (@pxref{Redirections}) associated with a compound command +apply to all commands within that compound command unless explicitly overridden. + +Bash provides looping constructs, conditional commands, and mechanisms +to group commands and execute them as a unit. + +@node Looping Constructs +@subsubsection Looping Constructs +@cindex commands, looping + +Bash supports the following looping constructs. + +Note that wherever a @samp{;} appears in the description of a +command's syntax, it may be replaced with one or more newlines. + +@table @code +@item until +@rwindex until +@rwindex do +@rwindex done +The syntax of the @code{until} command is: +@example +until @var{test-commands}; do @var{consequent-commands}; done +@end example +Execute @var{consequent-commands} as long as +@var{test-commands} has an exit status which is not zero. +The return status is the exit status of the last command executed +in @var{consequent-commands}, or zero if none was executed. + +@item while +@rwindex while +The syntax of the @code{while} command is: +@example +while @var{test-commands}; do @var{consequent-commands}; done +@end example + +Execute @var{consequent-commands} as long as +@var{test-commands} has an exit status of zero. +The return status is the exit status of the last command executed +in @var{consequent-commands}, or zero if none was executed. + +@item for +@rwindex for +The syntax of the @code{for} command is: + +@example +for @var{name} [in @var{words} @dots{}]; do @var{commands}; done +@end example +Expand @var{words}, and execute @var{commands} once for each member +in the resultant list, with @var{name} bound to the current member. +If @samp{in @var{words}} is not present, the @code{for} command +executes the @var{commands} once for each positional parameter that is +set, as if @samp{in "$@@"} had been specified +(@pxref{Special Parameters}). +The return status is the exit status of the last command that executes. +If there are no items in the expansion of @var{words}, no commands are +executed, and the return status is zero. + +An alternate form of the @code{for} command is also supported: + +@example +for (( @var{expr1} ; @var{expr2} ; @var{expr3} )) ; do @var{commands} ; done +@end example +First, the arithmetic expression @var{expr1} is evaluated according +to the rules described below (@pxref{Shell Arithmetic}). +The arithmetic expression @var{expr2} is then evaluated repeatedly +until it evaluates to zero. +Each time @var{expr2} evaluates to a non-zero value, @var{commands} are +executed and the arithmetic expression @var{expr3} is evaluated. +If any expression is omitted, it behaves as if it evaluates to 1. +The return value is the exit status of the last command in @var{list} +that is executed, or false if any of the expressions is invalid. + +@end table + +The @code{break} and @code{continue} builtins (@pxref{Bourne Shell Builtins}) +may be used to control loop execution. + +@node Conditional Constructs +@subsubsection Conditional Constructs +@cindex commands, conditional + +@table @code +@item if +@rwindex if +@rwindex then +@rwindex else +@rwindex elif +@rwindex fi +The syntax of the @code{if} command is: + +@example +if @var{test-commands}; then + @var{consequent-commands}; +[elif @var{more-test-commands}; then + @var{more-consequents};] +[else @var{alternate-consequents};] +fi +@end example + +The @var{test-commands} list is executed, and if its return status is zero, +the @var{consequent-commands} list is executed. +If @var{test-commands} returns a non-zero status, each @code{elif} list +is executed in turn, and if its exit status is zero, +the corresponding @var{more-consequents} is executed and the +command completes. +If @samp{else @var{alternate-consequents}} is present, and +the final command in the final @code{if} or @code{elif} clause +has a non-zero exit status, then @var{alternate-consequents} is executed. +The return status is the exit status of the last command executed, or +zero if no condition tested true. + +@item case +@rwindex case +@rwindex in +@rwindex esac +The syntax of the @code{case} command is: + +@example +@code{case @var{word} in [ [(] @var{pattern} [| @var{pattern}]@dots{}) @var{command-list} ;;]@dots{} esac} +@end example + +@code{case} will selectively execute the @var{command-list} corresponding to +the first @var{pattern} that matches @var{word}. +If the shell option @code{nocasematch} +(see the description of @code{shopt} in @ref{The Shopt Builtin}) +is enabled, the match is performed without regard to the case +of alphabetic characters. +The @samp{|} is used to separate multiple patterns, and the @samp{)} +operator terminates a pattern list. +A list of patterns and an associated command-list is known +as a @var{clause}. Each clause must be terminated with @samp{;;}. +The @var{word} undergoes tilde expansion, parameter expansion, command +substitution, arithmetic expansion, and quote removal before matching is +attempted. Each @var{pattern} undergoes tilde expansion, parameter +expansion, command substitution, and arithmetic expansion. + +There may be an arbitrary number of @code{case} clauses, each terminated +by a @samp{;;}. The first pattern that matches determines the +command-list that is executed. + +Here is an example using @code{case} in a script that could be used to +describe one interesting feature of an animal: + +@example +echo -n "Enter the name of an animal: " +read ANIMAL +echo -n "The $ANIMAL has " +case $ANIMAL in + horse | dog | cat) echo -n "four";; + man | kangaroo ) echo -n "two";; + *) echo -n "an unknown number of";; +esac +echo " legs." +@end example + +@noindent +The return status is zero if no @var{pattern} is matched. Otherwise, the +return status is the exit status of the @var{command-list} executed. + +@item select +@rwindex select + +The @code{select} construct allows the easy generation of menus. +It has almost the same syntax as the @code{for} command: + +@example +select @var{name} [in @var{words} @dots{}]; do @var{commands}; done +@end example + +The list of words following @code{in} is expanded, generating a list +of items. The set of expanded words is printed on the standard +error output stream, each preceded by a number. If the +@samp{in @var{words}} is omitted, the positional parameters are printed, +as if @samp{in "$@@"} had been specified. +The @env{PS3} prompt is then displayed and a line is read from the +standard input. +If the line consists of a number corresponding to one of the displayed +words, then the value of @var{name} is set to that word. +If the line is empty, the words and prompt are displayed again. +If @code{EOF} is read, the @code{select} command completes. +Any other value read causes @var{name} to be set to null. +The line read is saved in the variable @env{REPLY}. + +The @var{commands} are executed after each selection until a +@code{break} command is executed, at which +point the @code{select} command completes. + +Here is an example that allows the user to pick a filename from the +current directory, and displays the name and index of the file +selected. + +@example +select fname in *; +do + echo you picked $fname \($REPLY\) + break; +done +@end example + +@item ((@dots{})) +@example +(( @var{expression} )) +@end example + +The arithmetic @var{expression} is evaluated according to the rules +described below (@pxref{Shell Arithmetic}). +If the value of the expression is non-zero, the return status is 0; +otherwise the return status is 1. This is exactly equivalent to +@example +let "@var{expression}" +@end example +@noindent +@xref{Bash Builtins}, for a full description of the @code{let} builtin. + +@item [[@dots{}]] +@rwindex [[ +@rwindex ]] +@example +[[ @var{expression} ]] +@end example + +Return a status of 0 or 1 depending on the evaluation of +the conditional expression @var{expression}. +Expressions are composed of the primaries described below in +@ref{Bash Conditional Expressions}. +Word splitting and filename expansion are not performed on the words +between the @samp{[[} and @samp{]]}; tilde expansion, parameter and +variable expansion, arithmetic expansion, command substitution, process +substitution, and quote removal are performed. +Conditional operators such as @samp{-f} must be unquoted to be recognized +as primaries. + +When the @samp{==} and @samp{!=} operators are used, the string to the +right of the operator is considered a pattern and matched according +to the rules described below in @ref{Pattern Matching}. +If the shell option @code{nocasematch} +(see the description of @code{shopt} in @ref{The Shopt Builtin}) +is enabled, the match is performed without regard to the case +of alphabetic characters. +The return value is 0 if the string matches (@samp{==}) or does not +match (@samp{!=})the pattern, and 1 otherwise. +Any part of the pattern may be quoted to force it to be matched as a +string. + +An additional binary operator, @samp{=~}, is available, with the same +precedence as @samp{==} and @samp{!=}. +When it is used, the string to the right of the operator is considered +an extended regular expression and matched accordingly (as in @i{regex}3)). +The return value is 0 if the string matches +the pattern, and 1 otherwise. +If the regular expression is syntactically incorrect, the conditional +expression's return value is 2. +If the shell option @code{nocasematch} +(see the description of @code{shopt} in @ref{The Shopt Builtin}) +is enabled, the match is performed without regard to the case +of alphabetic characters. +Substrings matched by parenthesized subexpressions within the regular +expression are saved in the array variable @code{BASH_REMATCH}. +The element of @code{BASH_REMATCH} with index 0 is the portion of the string +matching the entire regular expression. +The element of @code{BASH_REMATCH} with index @var{n} is the portion of the +string matching the @var{n}th parenthesized subexpression. + +Expressions may be combined using the following operators, listed +in decreasing order of precedence: + +@table @code +@item ( @var{expression} ) +Returns the value of @var{expression}. +This may be used to override the normal precedence of operators. + +@item ! @var{expression} +True if @var{expression} is false. + +@item @var{expression1} && @var{expression2} +True if both @var{expression1} and @var{expression2} are true. + +@item @var{expression1} || @var{expression2} +True if either @var{expression1} or @var{expression2} is true. +@end table +@noindent +The @code{&&} and @code{||} operators do not evaluate @var{expression2} if the +value of @var{expression1} is sufficient to determine the return +value of the entire conditional expression. + +@end table + +@node Command Grouping +@subsubsection Grouping Commands +@cindex commands, grouping + +Bash provides two ways to group a list of commands to be executed +as a unit. When commands are grouped, redirections may be applied +to the entire command list. For example, the output of all the +commands in the list may be redirected to a single stream. + +@table @code +@item () +@example +( @var{list} ) +@end example + +Placing a list of commands between parentheses causes a subshell +environment to be created (@pxref{Command Execution Environment}), and each +of the commands in @var{list} to be executed in that subshell. Since the +@var{list} is executed in a subshell, variable assignments do not remain in +effect after the subshell completes. + +@item @{@} +@rwindex @{ +@rwindex @} +@example +@{ @var{list}; @} +@end example + +Placing a list of commands between curly braces causes the list to +be executed in the current shell context. No subshell is created. +The semicolon (or newline) following @var{list} is required. +@end table + +In addition to the creation of a subshell, there is a subtle difference +between these two constructs due to historical reasons. The braces +are @code{reserved words}, so they must be separated from the @var{list} +by @code{blank}s. The parentheses are @code{operators}, and are +recognized as separate tokens by the shell even if they are not separated +from the @var{list} by whitespace. + +The exit status of both of these constructs is the exit status of +@var{list}. + +@node Shell Functions +@section Shell Functions +@cindex shell function +@cindex functions, shell + +Shell functions are a way to group commands for later execution +using a single name for the group. They are executed just like +a "regular" command. +When the name of a shell function is used as a simple command name, +the list of commands associated with that function name is executed. +Shell functions are executed in the current +shell context; no new process is created to interpret them. + +Functions are declared using this syntax: +@rwindex function +@example +[ @code{function} ] @var{name} () @var{compound-command} [ @var{redirections} ] +@end example + +This defines a shell function named @var{name}. The reserved +word @code{function} is optional. +If the @code{function} reserved +word is supplied, the parentheses are optional. +The @var{body} of the function is the compound command +@var{compound-command} (@pxref{Compound Commands}). +That command is usually a @var{list} enclosed between @{ and @}, but +may be any compound command listed above. +@var{compound-command} is executed whenever @var{name} is specified as the +name of a command. +Any redirections (@pxref{Redirections}) associated with the shell function +are performed when the function is executed. + +A function definition may be deleted using the @option{-f} option to the +@code{unset} builtin (@pxref{Bourne Shell Builtins}). + +The exit status of a function definition is zero unless a syntax error +occurs or a readonly function with the same name already exists. +When executed, the exit status of a function is the exit status of the +last command executed in the body. + +Note that for historical reasons, in the most common usage the curly braces +that surround the body of the function must be separated from the body by +@code{blank}s or newlines. +This is because the braces are reserved words and are only recognized +as such when they are separated by whitespace. +Also, when using the braces, the @var{list} must be terminated by a semicolon, +a @samp{&}, or a newline. + +When a function is executed, the arguments to the +function become the positional parameters +during its execution (@pxref{Positional Parameters}). +The special parameter @samp{#} that expands to the number of +positional parameters is updated to reflect the change. +Special parameter @code{0} is unchanged. +The first element of the @env{FUNCNAME} variable is set to the +name of the function while the function is executing. +All other aspects of the shell execution +environment are identical between a function and its caller +with the exception that the @env{DEBUG} and @env{RETURN} traps +are not inherited unless the function has been given the +@code{trace} attribute using the @code{declare} builtin or +the @code{-o functrace} option has been enabled with +the @code{set} builtin, +(in which case all functions inherit the @env{DEBUG} and @env{RETURN} traps). +@xref{Bourne Shell Builtins}, for the description of the +@code{trap} builtin. + +If the builtin command @code{return} +is executed in a function, the function completes and +execution resumes with the next command after the function +call. +Any command associated with the @code{RETURN} trap is executed +before execution resumes. +When a function completes, the values of the +positional parameters and the special parameter @samp{#} +are restored to the values they had prior to the function's +execution. If a numeric argument is given to @code{return}, +that is the function's return status; otherwise the function's +return status is the exit status of the last command executed +before the @code{return}. + +Variables local to the function may be declared with the +@code{local} builtin. These variables are visible only to +the function and the commands it invokes. + +Function names and definitions may be listed with the +@option{-f} option to the @code{declare} or @code{typeset} +builtin commands (@pxref{Bash Builtins}). +The @option{-F} option to @code{declare} or @code{typeset} +will list the function names only +(and optionally the source file and line number, if the @code{extdebug} +shell option is enabled). +Functions may be exported so that subshells +automatically have them defined with the +@option{-f} option to the @code{export} builtin +(@pxref{Bourne Shell Builtins}). +Note that shell functions and variables with the same name may result +in multiple identically-named entries in the environment passed to the +shell's children. +Care should be taken in cases where this may cause a problem. + +Functions may be recursive. No limit is placed on the number of +recursive calls. + +@node Shell Parameters +@section Shell Parameters +@cindex parameters +@cindex variable, shell +@cindex shell variable + +@menu +* Positional Parameters:: The shell's command-line arguments. +* Special Parameters:: Parameters denoted by special characters. +@end menu + +A @var{parameter} is an entity that stores values. +It can be a @code{name}, a number, or one of the special characters +listed below. +A @var{variable} is a parameter denoted by a @code{name}. +A variable has a @var{value} and zero or more @var{attributes}. +Attributes are assigned using the @code{declare} builtin command +(see the description of the @code{declare} builtin in @ref{Bash Builtins}). + +A parameter is set if it has been assigned a value. The null string is +a valid value. Once a variable is set, it may be unset only by using +the @code{unset} builtin command. + +A variable may be assigned to by a statement of the form +@example +@var{name}=[@var{value}] +@end example +@noindent +If @var{value} +is not given, the variable is assigned the null string. All +@var{value}s undergo tilde expansion, parameter and variable expansion, +command substitution, arithmetic expansion, and quote +removal (detailed below). If the variable has its @code{integer} +attribute set, then @var{value} +is evaluated as an arithmetic expression even if the @code{$((@dots{}))} +expansion is not used (@pxref{Arithmetic Expansion}). +Word splitting is not performed, with the exception +of @code{"$@@"} as explained below. +Filename expansion is not performed. +Assignment statements may also appear as arguments to the +@code{alias}, +@code{declare}, @code{typeset}, @code{export}, @code{readonly}, +and @code{local} builtin commands. + +In the context where an assignment statement is assigning a value +to a shell variable or array index (@pxref{Arrays}), the @samp{+=} +operator can be used to +append to or add to the variable's previous value. +When @samp{+=} is applied to a variable for which the integer attribute +has been set, @var{value} is evaluated as an arithmetic expression and +added to the variable's current value, which is also evaluated. +When @samp{+=} is applied to an array variable using compound assignment +(@pxref{Arrays}), the +variable's value is not unset (as it is when using @samp{=}), and new +values are appended to the array beginning at one greater than the array's +maximum index. +When applied to a string-valued variable, @var{value} is expanded and +appended to the variable's value. + +@node Positional Parameters +@subsection Positional Parameters +@cindex parameters, positional + +A @var{positional parameter} is a parameter denoted by one or more +digits, other than the single digit @code{0}. Positional parameters are +assigned from the shell's arguments when it is invoked, +and may be reassigned using the @code{set} builtin command. +Positional parameter @code{N} may be referenced as @code{$@{N@}}, or +as @code{$N} when @code{N} consists of a single digit. +Positional parameters may not be assigned to with assignment statements. +The @code{set} and @code{shift} builtins are used to set and +unset them (@pxref{Shell Builtin Commands}). +The positional parameters are +temporarily replaced when a shell function is executed +(@pxref{Shell Functions}). + +When a positional parameter consisting of more than a single +digit is expanded, it must be enclosed in braces. + +@node Special Parameters +@subsection Special Parameters +@cindex parameters, special + +The shell treats several parameters specially. These parameters may +only be referenced; assignment to them is not allowed. + +@vtable @code + +@item * +Expands to the positional parameters, starting from one. When the +expansion occurs within double quotes, it expands to a single word +with the value of each parameter separated by the first character +of the @env{IFS} +special variable. That is, @code{"$*"} is equivalent +to @code{"$1@var{c}$2@var{c}@dots{}"}, where @var{c} +is the first character of the value of the @code{IFS} +variable. +If @env{IFS} is unset, the parameters are separated by spaces. +If @env{IFS} is null, the parameters are joined without intervening +separators. + + +@item @@ +Expands to the positional parameters, starting from one. When the +expansion occurs within double quotes, each parameter expands to a +separate word. That is, @code{"$@@"} is equivalent to +@code{"$1" "$2" @dots{}}. +If the double-quoted expansion occurs within a word, the expansion of +the first parameter is joined with the beginning part of the original +word, and the expansion of the last parameter is joined with the last +part of the original word. +When there are no positional parameters, @code{"$@@"} and +@code{$@@} +expand to nothing (i.e., they are removed). + +@item # +Expands to the number of positional parameters in decimal. + +@item ? +Expands to the exit status of the most recently executed foreground +pipeline. + +@item - +(A hyphen.) Expands to the current option flags as specified upon +invocation, by the @code{set} +builtin command, or those set by the shell itself +(such as the @option{-i} option). + +@item $ +Expands to the process @sc{id} of the shell. In a @code{()} subshell, it +expands to the process @sc{id} of the invoking shell, not the subshell. + +@item ! +Expands to the process @sc{id} of the most recently executed background +(asynchronous) command. + +@item 0 +Expands to the name of the shell or shell script. This is set at +shell initialization. If Bash is invoked with a file of commands +(@pxref{Shell Scripts}), @code{$0} is set to the name of that file. +If Bash is started with the @option{-c} option (@pxref{Invoking Bash}), +then @code{$0} is set to the first argument after the string to be +executed, if one is present. Otherwise, it is set +to the filename used to invoke Bash, as given by argument zero. + +@item _ +(An underscore.) +At shell startup, set to the absolute pathname used to invoke the +shell or shell script being executed as passed in the environment +or argument list. +Subsequently, expands to the last argument to the previous command, +after expansion. +Also set to the full pathname used to invoke each command executed +and placed in the environment exported to that command. +When checking mail, this parameter holds the name of the mail file. +@end vtable + +@node Shell Expansions +@section Shell Expansions +@cindex expansion + +Expansion is performed on the command line after it has been split into +@code{token}s. There are seven kinds of expansion performed: +@itemize @bullet +@item brace expansion +@item tilde expansion +@item parameter and variable expansion +@item command substitution +@item arithmetic expansion +@item word splitting +@item filename expansion +@end itemize + +@menu +* Brace Expansion:: Expansion of expressions within braces. +* Tilde Expansion:: Expansion of the ~ character. +* Shell Parameter Expansion:: How Bash expands variables to their values. +* Command Substitution:: Using the output of a command as an argument. +* Arithmetic Expansion:: How to use arithmetic in shell expansions. +* Process Substitution:: A way to write and read to and from a + command. +* Word Splitting:: How the results of expansion are split into separate + arguments. +* Filename Expansion:: A shorthand for specifying filenames matching patterns. +* Quote Removal:: How and when quote characters are removed from + words. +@end menu + +The order of expansions is: brace expansion, tilde expansion, +parameter, variable, and arithmetic expansion and +command substitution +(done in a left-to-right fashion), word splitting, and filename +expansion. + +On systems that can support it, there is an additional expansion +available: @var{process substitution}. This is performed at the +same time as parameter, variable, and arithmetic expansion and +command substitution. + +Only brace expansion, word splitting, and filename expansion +can change the number of words of the expansion; other expansions +expand a single word to a single word. +The only exceptions to this are the expansions of +@code{"$@@"} (@pxref{Special Parameters}) and @code{"$@{@var{name}[@@]@}"} +(@pxref{Arrays}). + +After all expansions, @code{quote removal} (@pxref{Quote Removal}) +is performed. + +@node Brace Expansion +@subsection Brace Expansion +@cindex brace expansion +@cindex expansion, brace + +Brace expansion is a mechanism by which arbitrary strings may be generated. +This mechanism is similar to +@var{filename expansion} (@pxref{Filename Expansion}), +but the file names generated need not exist. +Patterns to be brace expanded take the form of an optional @var{preamble}, +followed by either a series of comma-separated strings or a seqeunce expression +between a pair of braces, +followed by an optional @var{postscript}. +The preamble is prefixed to each string contained within the braces, and +the postscript is then appended to each resulting string, expanding left +to right. + +Brace expansions may be nested. +The results of each expanded string are not sorted; left to right order +is preserved. +For example, +@example +bash$ echo a@{d,c,b@}e +ade ace abe +@end example + +A sequence expression takes the form @code{@{@var{x}..@var{y}@}}, +where @var{x} and @var{y} are either integers or single characters. +When integers are supplied, the expression expands to each number between +@var{x} and @var{y}, inclusive. +When characters are supplied, the expression expands to each character +lexicographically between @var{x} and @var{y}, inclusive. Note that +both @var{x} and @var{y} must be of the same type. + +Brace expansion is performed before any other expansions, +and any characters special to other expansions are preserved +in the result. It is strictly textual. Bash +does not apply any syntactic interpretation to the context of the +expansion or the text between the braces. +To avoid conflicts with parameter expansion, the string @samp{$@{} +is not considered eligible for brace expansion. + +A correctly-formed brace expansion must contain unquoted opening +and closing braces, and at least one unquoted comma or a valid +sequence expression. +Any incorrectly formed brace expansion is left unchanged. + +A @{ or @samp{,} may be quoted with a backslash to prevent its +being considered part of a brace expression. +To avoid conflicts with parameter expansion, the string @samp{$@{} +is not considered eligible for brace expansion. + +This construct is typically used as shorthand when the common +prefix of the strings to be generated is longer than in the +above example: +@example +mkdir /usr/local/src/bash/@{old,new,dist,bugs@} +@end example +or +@example +chown root /usr/@{ucb/@{ex,edit@},lib/@{ex?.?*,how_ex@}@} +@end example + +@node Tilde Expansion +@subsection Tilde Expansion +@cindex tilde expansion +@cindex expansion, tilde + +If a word begins with an unquoted tilde character (@samp{~}), all of the +characters up to the first unquoted slash (or all characters, +if there is no unquoted slash) are considered a @var{tilde-prefix}. +If none of the characters in the tilde-prefix are quoted, the +characters in the tilde-prefix following the tilde are treated as a +possible @var{login name}. +If this login name is the null string, the tilde is replaced with the +value of the @env{HOME} shell variable. +If @env{HOME} is unset, the home directory of the user executing the +shell is substituted instead. +Otherwise, the tilde-prefix is replaced with the home directory +associated with the specified login name. + +If the tilde-prefix is @samp{~+}, the value of +the shell variable @env{PWD} replaces the tilde-prefix. +If the tilde-prefix is @samp{~-}, the value of the shell variable +@env{OLDPWD}, if it is set, is substituted. + +If the characters following the tilde in the tilde-prefix consist of a +number @var{N}, optionally prefixed by a @samp{+} or a @samp{-}, +the tilde-prefix is replaced with the +corresponding element from the directory stack, as it would be displayed +by the @code{dirs} builtin invoked with the characters following tilde +in the tilde-prefix as an argument (@pxref{The Directory Stack}). +If the tilde-prefix, sans the tilde, consists of a number without a +leading @samp{+} or @samp{-}, @samp{+} is assumed. + +If the login name is invalid, or the tilde expansion fails, the word is +left unchanged. + +Each variable assignment is checked for unquoted tilde-prefixes immediately +following a @samp{:} or the first @samp{=}. +In these cases, tilde expansion is also performed. +Consequently, one may use file names with tildes in assignments to +@env{PATH}, @env{MAILPATH}, and @env{CDPATH}, +and the shell assigns the expanded value. + +The following table shows how Bash treats unquoted tilde-prefixes: + +@table @code +@item ~ +The value of @code{$HOME} +@item ~/foo +@file{$HOME/foo} + +@item ~fred/foo +The subdirectory @code{foo} of the home directory of the user +@code{fred} + +@item ~+/foo +@file{$PWD/foo} + +@item ~-/foo +@file{$@{OLDPWD-'~-'@}/foo} + +@item ~@var{N} +The string that would be displayed by @samp{dirs +@var{N}} + +@item ~+@var{N} +The string that would be displayed by @samp{dirs +@var{N}} + +@item ~-@var{N} +The string that would be displayed by @samp{dirs -@var{N}} + +@end table + +@node Shell Parameter Expansion +@subsection Shell Parameter Expansion +@cindex parameter expansion +@cindex expansion, parameter + +The @samp{$} character introduces parameter expansion, +command substitution, or arithmetic expansion. The parameter name +or symbol to be expanded may be enclosed in braces, which +are optional but serve to protect the variable to be expanded from +characters immediately following it which could be +interpreted as part of the name. + +When braces are used, the matching ending brace is the first @samp{@}} +not escaped by a backslash or within a quoted string, and not within an +embedded arithmetic expansion, command substitution, or parameter +expansion. + +The basic form of parameter expansion is $@{@var{parameter}@}. +The value of @var{parameter} is substituted. The braces are required +when @var{parameter} +is a positional parameter with more than one digit, +or when @var{parameter} +is followed by a character that is not to be +interpreted as part of its name. + +If the first character of @var{parameter} is an exclamation point, +a level of variable indirection is introduced. +Bash uses the value of the variable formed from the rest of +@var{parameter} as the name of the variable; this variable is then +expanded and that value is used in the rest of the substitution, rather +than the value of @var{parameter} itself. +This is known as @code{indirect expansion}. +The exceptions to this are the expansions of $@{!@var{prefix*}@} +and $@{!@var{name}[@@]@} +described below. +The exclamation point must immediately follow the left brace in order to +introduce indirection. + +In each of the cases below, @var{word} is subject to tilde expansion, +parameter expansion, command substitution, and arithmetic expansion. + +When not performing substring expansion, Bash tests for a parameter +that is unset or null; omitting the colon results in a test only for a +parameter that is unset. Put another way, if the colon is included, +the operator tests for both existence and that the value is not null; +if the colon is omitted, the operator tests only for existence. + +@table @code + +@item $@{@var{parameter}:@minus{}@var{word}@} +If @var{parameter} is unset or null, the expansion of +@var{word} is substituted. Otherwise, the value of +@var{parameter} is substituted. + +@item $@{@var{parameter}:=@var{word}@} +If @var{parameter} +is unset or null, the expansion of @var{word} +is assigned to @var{parameter}. +The value of @var{parameter} is then substituted. +Positional parameters and special parameters may not be assigned to +in this way. + +@item $@{@var{parameter}:?@var{word}@} +If @var{parameter} +is null or unset, the expansion of @var{word} (or a message +to that effect if @var{word} +is not present) is written to the standard error and the shell, if it +is not interactive, exits. Otherwise, the value of @var{parameter} is +substituted. + +@item $@{@var{parameter}:+@var{word}@} +If @var{parameter} +is null or unset, nothing is substituted, otherwise the expansion of +@var{word} is substituted. + +@item $@{@var{parameter}:@var{offset}@} +@itemx $@{@var{parameter}:@var{offset}:@var{length}@} +Expands to up to @var{length} characters of @var{parameter} +starting at the character specified by @var{offset}. +If @var{length} is omitted, expands to the substring of +@var{parameter} starting at the character specified by @var{offset}. +@var{length} and @var{offset} are arithmetic expressions +(@pxref{Shell Arithmetic}). +This is referred to as Substring Expansion. + +@var{length} must evaluate to a number greater than or equal to zero. +If @var{offset} evaluates to a number less than zero, the value +is used as an offset from the end of the value of @var{parameter}. +If @var{parameter} is @samp{@@}, the result is @var{length} positional +parameters beginning at @var{offset}. +If @var{parameter} is an array name indexed by @samp{@@} or @samp{*}, +the result is the @var{length} +members of the array beginning with @code{$@{@var{parameter}[@var{offset}]@}}. +A negative @var{offset} is taken relative to one greater than the maximum +index of the specified array. +Note that a negative offset must be separated from the colon by at least +one space to avoid being confused with the @samp{:-} expansion. +Substring indexing is zero-based unless the positional parameters +are used, in which case the indexing starts at 1 by default. +If @var{offset} is 0, and the positional parameters are used, @code{$@@} is +prefixed to the list. + +@item $@{!@var{prefix}*@} +@itemx $@{!@var{prefix}@@@} +Expands to the names of variables whose names begin with @var{prefix}, +separated by the first character of the @env{IFS} special variable. +When @samp{@@} is used and the expansion appears within double quotes, each +variable name expands to a separate word. + +@item $@{!@var{name}[@@]@} +@itemx $@{!@var{name}[*]@} +If @var{name} is an array variable, expands to the list of array indices +(keys) assigned in @var{name}. +If @var{name} is not an array, expands to 0 if @var{name} is set and null +otherwise. +When @samp{@@} is used and the expansion appears within double quotes, each +key expands to a separate word. + +@item $@{#@var{parameter}@} +The length in characters of the expanded value of @var{parameter} is +substituted. +If @var{parameter} is @samp{*} or @samp{@@}, the value substituted +is the number of positional parameters. +If @var{parameter} is an array name subscripted by @samp{*} or @samp{@@}, +the value substituted is the number of elements in the array. + +@item $@{@var{parameter}#@var{word}@} +@itemx $@{@var{parameter}##@var{word}@} +The @var{word} +is expanded to produce a pattern just as in filename +expansion (@pxref{Filename Expansion}). If the pattern matches +the beginning of the expanded value of @var{parameter}, +then the result of the expansion is the expanded value of @var{parameter} +with the shortest matching pattern (the @samp{#} case) or the +longest matching pattern (the @samp{##} case) deleted. +If @var{parameter} is @samp{@@} or @samp{*}, +the pattern removal operation is applied to each positional +parameter in turn, and the expansion is the resultant list. +If @var{parameter} is an array variable subscripted with +@samp{@@} or @samp{*}, +the pattern removal operation is applied to each member of the +array in turn, and the expansion is the resultant list. + +@item $@{@var{parameter}%@var{word}@} +@itemx $@{@var{parameter}%%@var{word}@} +The @var{word} is expanded to produce a pattern just as in +filename expansion. +If the pattern matches a trailing portion of the expanded value of +@var{parameter}, then the result of the expansion is the value of +@var{parameter} with the shortest matching pattern (the @samp{%} case) +or the longest matching pattern (the @samp{%%} case) deleted. +If @var{parameter} is @samp{@@} or @samp{*}, +the pattern removal operation is applied to each positional +parameter in turn, and the expansion is the resultant list. +If @var{parameter} +is an array variable subscripted with @samp{@@} or @samp{*}, +the pattern removal operation is applied to each member of the +array in turn, and the expansion is the resultant list. + +@item $@{@var{parameter}/@var{pattern}/@var{string}@} + +The @var{pattern} is expanded to produce a pattern just as in +filename expansion. +@var{Parameter} is expanded and the longest match of @var{pattern} +against its value is replaced with @var{string}. +If @var{pattern} begins with @samp{/}, all matches of @var{pattern} are +replaced with @var{string}. Normally only the first match is replaced. +If @var{pattern} begins with @samp{#}, it must match at the beginning +of the expanded value of @var{parameter}. +If @var{pattern} begins with @samp{%}, it must match at the end +of the expanded value of @var{parameter}. +If @var{string} is null, matches of @var{pattern} are deleted +and the @code{/} following @var{pattern} may be omitted. +If @var{parameter} is @samp{@@} or @samp{*}, +the substitution operation is applied to each positional +parameter in turn, and the expansion is the resultant list. +If @var{parameter} +is an array variable subscripted with @samp{@@} or @samp{*}, +the substitution operation is applied to each member of the +array in turn, and the expansion is the resultant list. + +@end table + +@node Command Substitution +@subsection Command Substitution +@cindex command substitution + +Command substitution allows the output of a command to replace +the command itself. +Command substitution occurs when a command is enclosed as follows: +@example +$(@var{command}) +@end example +@noindent +or +@example +`@var{command}` +@end example + +@noindent +Bash performs the expansion by executing @var{command} and +replacing the command substitution with the standard output of the +command, with any trailing newlines deleted. +Embedded newlines are not deleted, but they may be removed during +word splitting. +The command substitution @code{$(cat @var{file})} can be +replaced by the equivalent but faster @code{$(< @var{file})}. + +When the old-style backquote form of substitution is used, +backslash retains its literal meaning except when followed by +@samp{$}, @samp{`}, or @samp{\}. +The first backquote not preceded by a backslash terminates the +command substitution. +When using the @code{$(@var{command})} form, all characters between +the parentheses make up the command; none are treated specially. + +Command substitutions may be nested. To nest when using the backquoted +form, escape the inner backquotes with backslashes. + +If the substitution appears within double quotes, word splitting and +filename expansion are not performed on the results. + +@node Arithmetic Expansion +@subsection Arithmetic Expansion +@cindex expansion, arithmetic +@cindex arithmetic expansion + +Arithmetic expansion allows the evaluation of an arithmetic expression +and the substitution of the result. The format for arithmetic expansion is: + +@example +$(( @var{expression} )) +@end example + +The expression is treated as if it were within double quotes, but +a double quote inside the parentheses is not treated specially. +All tokens in the expression undergo parameter expansion, command +substitution, and quote removal. +Arithmetic expansions may be nested. + +The evaluation is performed according to the rules listed below +(@pxref{Shell Arithmetic}). +If the expression is invalid, Bash prints a message indicating +failure to the standard error and no substitution occurs. + +@node Process Substitution +@subsection Process Substitution +@cindex process substitution + +Process substitution is supported on systems that support named +pipes (@sc{fifo}s) or the @file{/dev/fd} method of naming open files. +It takes the form of +@example +<(@var{list}) +@end example +@noindent +or +@example +>(@var{list}) +@end example +@noindent +The process @var{list} is run with its input or output connected to a +@sc{fifo} or some file in @file{/dev/fd}. The name of this file is +passed as an argument to the current command as the result of the +expansion. If the @code{>(@var{list})} form is used, writing to +the file will provide input for @var{list}. If the +@code{<(@var{list})} form is used, the file passed as an +argument should be read to obtain the output of @var{list}. +Note that no space may appear between the @code{<} or @code{>} +and the left parenthesis, otherwise the construct would be interpreted +as a redirection. + +When available, process substitution is performed simultaneously with +parameter and variable expansion, command substitution, and arithmetic +expansion. + +@node Word Splitting +@subsection Word Splitting +@cindex word splitting + +The shell scans the results of parameter expansion, command substitution, +and arithmetic expansion that did not occur within double quotes for +word splitting. + +The shell treats each character of @env{$IFS} as a delimiter, and splits +the results of the other expansions into words on these characters. +If @env{IFS} is unset, or its value is exactly @code{}, +the default, then sequences of +@code{ }, @code{}, and @code{} +at the beginning and end of the results of the previous +expansions are ignored, and any sequence of @env{IFS} +characters not at the beginning or end serves to delimit words. +If @env{IFS} has a value other than the default, then sequences of +the whitespace characters @code{space} and @code{tab} +are ignored at the beginning and end of the +word, as long as the whitespace character is in the +value of @env{IFS} (an @env{IFS} whitespace character). +Any character in @env{IFS} that is not @env{IFS} +whitespace, along with any adjacent @env{IFS} +whitespace characters, delimits a field. A sequence of @env{IFS} +whitespace characters is also treated as a delimiter. +If the value of @env{IFS} is null, no word splitting occurs. + +Explicit null arguments (@code{""} or @code{''}) are retained. +Unquoted implicit null arguments, resulting from the expansion of +parameters that have no values, are removed. +If a parameter with no value is expanded within double quotes, a +null argument results and is retained. + +Note that if no expansion occurs, no splitting +is performed. + +@node Filename Expansion +@subsection Filename Expansion +@menu +* Pattern Matching:: How the shell matches patterns. +@end menu +@cindex expansion, filename +@cindex expansion, pathname +@cindex filename expansion +@cindex pathname expansion + +After word splitting, unless the @option{-f} option has been set +(@pxref{The Set Builtin}), Bash scans each word for the characters +@samp{*}, @samp{?}, and @samp{[}. +If one of these characters appears, then the word is +regarded as a @var{pattern}, +and replaced with an alphabetically sorted list of +file names matching the pattern. If no matching file names are found, +and the shell option @code{nullglob} is disabled, the word is left +unchanged. +If the @code{nullglob} option is set, and no matches are found, the word +is removed. +If the @code{failglob} shell option is set, and no matches are found, +an error message is printed and the command is not executed. +If the shell option @code{nocaseglob} is enabled, the match is performed +without regard to the case of alphabetic characters. + +When a pattern is used for filename generation, the character @samp{.} +at the start of a filename or immediately following a slash +must be matched explicitly, unless the shell option @code{dotglob} is set. +When matching a file name, the slash character must always be +matched explicitly. +In other cases, the @samp{.} character is not treated specially. + +See the description of @code{shopt} in @ref{The Shopt Builtin}, +for a description of the @code{nocaseglob}, @code{nullglob}, +@code{failglob}, and @code{dotglob} options. + +The @env{GLOBIGNORE} +shell variable may be used to restrict the set of filenames matching a +pattern. If @env{GLOBIGNORE} +is set, each matching filename that also matches one of the patterns in +@env{GLOBIGNORE} is removed from the list of matches. The filenames +@file{.} and @file{..} +are always ignored when @env{GLOBIGNORE} +is set and not null. +However, setting @env{GLOBIGNORE} to a non-null value has the effect of +enabling the @code{dotglob} +shell option, so all other filenames beginning with a +@samp{.} will match. +To get the old behavior of ignoring filenames beginning with a +@samp{.}, make @samp{.*} one of the patterns in @env{GLOBIGNORE}. +The @code{dotglob} option is disabled when @env{GLOBIGNORE} +is unset. + +@node Pattern Matching +@subsubsection Pattern Matching +@cindex pattern matching +@cindex matching, pattern + +Any character that appears in a pattern, other than the special pattern +characters described below, matches itself. +The @sc{nul} character may not occur in a pattern. +A backslash escapes the following character; the +escaping backslash is discarded when matching. +The special pattern characters must be quoted if they are to be matched +literally. + +The special pattern characters have the following meanings: +@table @code +@item * +Matches any string, including the null string. +@item ? +Matches any single character. +@item [@dots{}] +Matches any one of the enclosed characters. A pair of characters +separated by a hyphen denotes a @var{range expression}; +any character that sorts between those two characters, inclusive, +using the current locale's collating sequence and character set, +is matched. If the first character following the +@samp{[} is a @samp{!} or a @samp{^} +then any character not enclosed is matched. A @samp{@minus{}} +may be matched by including it as the first or last character +in the set. A @samp{]} may be matched by including it as the first +character in the set. +The sorting order of characters in range expressions is determined by +the current locale and the value of the @env{LC_COLLATE} shell variable, +if set. + +For example, in the default C locale, @samp{[a-dx-z]} is equivalent to +@samp{[abcdxyz]}. Many locales sort characters in dictionary order, and in +these locales @samp{[a-dx-z]} is typically not equivalent to @samp{[abcdxyz]}; +it might be equivalent to @samp{[aBbCcDdxXyYz]}, for example. To obtain +the traditional interpretation of ranges in bracket expressions, you can +force the use of the C locale by setting the @env{LC_COLLATE} or +@env{LC_ALL} environment variable to the value @samp{C}. + +Within @samp{[} and @samp{]}, @var{character classes} can be specified +using the syntax +@code{[:}@var{class}@code{:]}, where @var{class} is one of the +following classes defined in the @sc{posix} standard: +@example +alnum alpha ascii blank cntrl digit graph lower +print punct space upper word xdigit +@end example +@noindent +A character class matches any character belonging to that class. +The @code{word} character class matches letters, digits, and the character +@samp{_}. + +Within @samp{[} and @samp{]}, an @var{equivalence class} can be +specified using the syntax @code{[=}@var{c}@code{=]}, which +matches all characters with the same collation weight (as defined +by the current locale) as the character @var{c}. + +Within @samp{[} and @samp{]}, the syntax @code{[.}@var{symbol}@code{.]} +matches the collating symbol @var{symbol}. +@end table + +If the @code{extglob} shell option is enabled using the @code{shopt} +builtin, several extended pattern matching operators are recognized. +In the following description, a @var{pattern-list} is a list of one +or more patterns separated by a @samp{|}. +Composite patterns may be formed using one or more of the following +sub-patterns: + +@table @code +@item ?(@var{pattern-list}) +Matches zero or one occurrence of the given patterns. + +@item *(@var{pattern-list}) +Matches zero or more occurrences of the given patterns. + +@item +(@var{pattern-list}) +Matches one or more occurrences of the given patterns. + +@item @@(@var{pattern-list}) +Matches one of the given patterns. + +@item !(@var{pattern-list}) +Matches anything except one of the given patterns. +@end table + +@node Quote Removal +@subsection Quote Removal + +After the preceding expansions, all unquoted occurrences of the +characters @samp{\}, @samp{'}, and @samp{"} that did not +result from one of the above expansions are removed. + +@node Redirections +@section Redirections +@cindex redirection + +Before a command is executed, its input and output +may be @var{redirected} +using a special notation interpreted by the shell. +Redirection may also be used to open and close files for the +current shell execution environment. The following redirection +operators may precede or appear anywhere within a +simple command or may follow a command. +Redirections are processed in the order they appear, from +left to right. + +In the following descriptions, if the file descriptor number is +omitted, and the first character of the redirection operator is +@samp{<}, the redirection refers to the standard input (file +descriptor 0). If the first character of the redirection operator +is @samp{>}, the redirection refers to the standard output (file +descriptor 1). + +The word following the redirection operator in the following +descriptions, unless otherwise noted, is subjected to brace expansion, +tilde expansion, parameter expansion, command substitution, arithmetic +expansion, quote removal, filename expansion, and word splitting. +If it expands to more than one word, Bash reports an error. + +Note that the order of redirections is significant. For example, +the command +@example +ls > @var{dirlist} 2>&1 +@end example +@noindent +directs both standard output (file descriptor 1) and standard error +(file descriptor 2) to the file @var{dirlist}, while the command +@example +ls 2>&1 > @var{dirlist} +@end example +@noindent +directs only the standard output to file @var{dirlist}, +because the standard error was duplicated as standard output +before the standard output was redirected to @var{dirlist}. + +Bash handles several filenames specially when they are used in +redirections, as described in the following table: + +@table @code +@item /dev/fd/@var{fd} +If @var{fd} is a valid integer, file descriptor @var{fd} is duplicated. + +@item /dev/stdin +File descriptor 0 is duplicated. + +@item /dev/stdout +File descriptor 1 is duplicated. + +@item /dev/stderr +File descriptor 2 is duplicated. + +@item /dev/tcp/@var{host}/@var{port} +If @var{host} is a valid hostname or Internet address, and @var{port} +is an integer port number or service name, Bash attempts to open a TCP +connection to the corresponding socket. + +@item /dev/udp/@var{host}/@var{port} +If @var{host} is a valid hostname or Internet address, and @var{port} +is an integer port number or service name, Bash attempts to open a UDP +connection to the corresponding socket. + +@end table + +A failure to open or create a file causes the redirection to fail. + +Redirections using file descriptors greater than 9 should be used with +care, as they may conflict with file descriptors the shell uses +internally. + +@subsection Redirecting Input +Redirection of input causes the file whose name results from +the expansion of @var{word} +to be opened for reading on file descriptor @code{n}, +or the standard input (file descriptor 0) if @code{n} +is not specified. + +The general format for redirecting input is: +@example +[@var{n}]<@var{word} +@end example + +@subsection Redirecting Output +Redirection of output causes the file whose name results from +the expansion of @var{word} +to be opened for writing on file descriptor @var{n}, +or the standard output (file descriptor 1) if @var{n} +is not specified. If the file does not exist it is created; +if it does exist it is truncated to zero size. + +The general format for redirecting output is: +@example +[@var{n}]>[|]@var{word} +@end example + +If the redirection operator is @samp{>}, and the @code{noclobber} +option to the @code{set} builtin has been enabled, the redirection +will fail if the file whose name results from the expansion of +@var{word} exists and is a regular file. +If the redirection operator is @samp{>|}, or the redirection operator is +@samp{>} and the @code{noclobber} option is not enabled, the redirection +is attempted even if the file named by @var{word} exists. + +@subsection Appending Redirected Output +Redirection of output in this fashion +causes the file whose name results from +the expansion of @var{word} +to be opened for appending on file descriptor @var{n}, +or the standard output (file descriptor 1) if @var{n} +is not specified. If the file does not exist it is created. + +The general format for appending output is: +@example +[@var{n}]>>@var{word} +@end example + +@subsection Redirecting Standard Output and Standard Error +Bash allows both the +standard output (file descriptor 1) and +the standard error output (file descriptor 2) +to be redirected to the file whose name is the +expansion of @var{word} with this construct. + +There are two formats for redirecting standard output and +standard error: +@example +&>@var{word} +@end example +@noindent +and +@example +>&@var{word} +@end example +@noindent +Of the two forms, the first is preferred. +This is semantically equivalent to +@example +>@var{word} 2>&1 +@end example + +@subsection Here Documents +This type of redirection instructs the shell to read input from the +current source until a line containing only @var{word} +(with no trailing blanks) is seen. All of +the lines read up to that point are then used as the standard +input for a command. + +The format of here-documents is: +@example +<<[@minus{}]@var{word} + @var{here-document} +@var{delimiter} +@end example + +No parameter expansion, command substitution, arithmetic expansion, +or filename expansion is performed on +@var{word}. If any characters in @var{word} are quoted, the +@var{delimiter} is the result of quote removal on @var{word}, +and the lines in the here-document are not expanded. +If @var{word} is unquoted, +all lines of the here-document are subjected to parameter expansion, +command substitution, and arithmetic expansion. In the latter +case, the character sequence @code{\newline} is ignored, and @samp{\} +must be used to quote the characters +@samp{\}, @samp{$}, and @samp{`}. + +If the redirection operator is @samp{<<-}, +then all leading tab characters are stripped from input lines and the +line containing @var{delimiter}. +This allows here-documents within shell scripts to be indented in a +natural fashion. + +@subsection Here Strings +A variant of here documents, the format is: +@example +<<< @var{word} +@end example + +The @var{word} is expanded and supplied to the command on its standard +input. + +@subsection Duplicating File Descriptors +The redirection operator +@example +[@var{n}]<&@var{word} +@end example +@noindent +is used to duplicate input file descriptors. +If @var{word} +expands to one or more digits, the file descriptor denoted by @var{n} +is made to be a copy of that file descriptor. +If the digits in @var{word} do not specify a file descriptor open for +input, a redirection error occurs. +If @var{word} +evaluates to @samp{-}, file descriptor @var{n} is closed. If +@var{n} is not specified, the standard input (file descriptor 0) is used. + +The operator +@example +[@var{n}]>&@var{word} +@end example +@noindent +is used similarly to duplicate output file descriptors. If +@var{n} is not specified, the standard output (file descriptor 1) is used. +If the digits in @var{word} do not specify a file descriptor open for +output, a redirection error occurs. +As a special case, if @var{n} is omitted, and @var{word} does not +expand to one or more digits, the standard output and standard +error are redirected as described previously. + +@subsection Moving File Descriptors +The redirection operator +@example +[@var{n}]<&@var{digit}- +@end example +@noindent +moves the file descriptor @var{digit} to file descriptor @var{n}, +or the standard input (file descriptor 0) if @var{n} is not specified. +@var{digit} is closed after being duplicated to @var{n}. + +Similarly, the redirection operator +@example +[@var{n}]>&@var{digit}- +@end example +@noindent +moves the file descriptor @var{digit} to file descriptor @var{n}, +or the standard output (file descriptor 1) if @var{n} is not specified. + +@subsection Opening File Descriptors for Reading and Writing +The redirection operator +@example +[@var{n}]<>@var{word} +@end example +@noindent +causes the file whose name is the expansion of @var{word} +to be opened for both reading and writing on file descriptor +@var{n}, or on file descriptor 0 if @var{n} +is not specified. If the file does not exist, it is created. + +@node Executing Commands +@section Executing Commands + +@menu +* Simple Command Expansion:: How Bash expands simple commands before + executing them. +* Command Search and Execution:: How Bash finds commands and runs them. +* Command Execution Environment:: The environment in which Bash + executes commands that are not + shell builtins. +* Environment:: The environment given to a command. +* Exit Status:: The status returned by commands and how Bash + interprets it. +* Signals:: What happens when Bash or a command it runs + receives a signal. +@end menu + +@node Simple Command Expansion +@subsection Simple Command Expansion +@cindex command expansion + +When a simple command is executed, the shell performs the following +expansions, assignments, and redirections, from left to right. + +@enumerate +@item +The words that the parser has marked as variable assignments (those +preceding the command name) and redirections are saved for later +processing. + +@item +The words that are not variable assignments or redirections are +expanded (@pxref{Shell Expansions}). +If any words remain after expansion, the first word +is taken to be the name of the command and the remaining words are +the arguments. + +@item +Redirections are performed as described above (@pxref{Redirections}). + +@item +The text after the @samp{=} in each variable assignment undergoes tilde +expansion, parameter expansion, command substitution, arithmetic expansion, +and quote removal before being assigned to the variable. +@end enumerate + +If no command name results, the variable assignments affect the current +shell environment. Otherwise, the variables are added to the environment +of the executed command and do not affect the current shell environment. +If any of the assignments attempts to assign a value to a readonly variable, +an error occurs, and the command exits with a non-zero status. + +If no command name results, redirections are performed, but do not +affect the current shell environment. A redirection error causes the +command to exit with a non-zero status. + +If there is a command name left after expansion, execution proceeds as +described below. Otherwise, the command exits. If one of the expansions +contained a command substitution, the exit status of the command is +the exit status of the last command substitution performed. If there +were no command substitutions, the command exits with a status of zero. + +@node Command Search and Execution +@subsection Command Search and Execution +@cindex command execution +@cindex command search + +After a command has been split into words, if it results in a +simple command and an optional list of arguments, the following +actions are taken. + +@enumerate +@item +If the command name contains no slashes, the shell attempts to +locate it. If there exists a shell function by that name, that +function is invoked as described in @ref{Shell Functions}. + +@item +If the name does not match a function, the shell searches for +it in the list of shell builtins. If a match is found, that +builtin is invoked. + +@item +If the name is neither a shell function nor a builtin, +and contains no slashes, Bash searches each element of +@env{$PATH} for a directory containing an executable file +by that name. Bash uses a hash table to remember the full +pathnames of executable files to avoid multiple @env{PATH} searches +(see the description of @code{hash} in @ref{Bourne Shell Builtins}). +A full search of the directories in @env{$PATH} +is performed only if the command is not found in the hash table. +If the search is unsuccessful, the shell prints an error +message and returns an exit status of 127. + +@item +If the search is successful, or if the command name contains +one or more slashes, the shell executes the named program in +a separate execution environment. +Argument 0 is set to the name given, and the remaining arguments +to the command are set to the arguments supplied, if any. + +@item +If this execution fails because the file is not in executable +format, and the file is not a directory, it is assumed to be a +@var{shell script} and the shell executes it as described in +@ref{Shell Scripts}. + +@item +If the command was not begun asynchronously, the shell waits for +the command to complete and collects its exit status. + +@end enumerate + +@node Command Execution Environment +@subsection Command Execution Environment +@cindex execution environment + +The shell has an @var{execution environment}, which consists of the +following: + +@itemize @bullet +@item +open files inherited by the shell at invocation, as modified by +redirections supplied to the @code{exec} builtin + +@item +the current working directory as set by @code{cd}, @code{pushd}, or +@code{popd}, or inherited by the shell at invocation + +@item +the file creation mode mask as set by @code{umask} or inherited from +the shell's parent + +@item +current traps set by @code{trap} + +@item +shell parameters that are set by variable assignment or with @code{set} +or inherited from the shell's parent in the environment + +@item +shell functions defined during execution or inherited from the shell's +parent in the environment + +@item +options enabled at invocation (either by default or with command-line +arguments) or by @code{set} + +@item +options enabled by @code{shopt} (@pxref{The Shopt Builtin}) + +@item +shell aliases defined with @code{alias} (@pxref{Aliases}) + +@item +various process @sc{id}s, including those of background jobs +(@pxref{Lists}), the value of @code{$$}, and the value of +@env{$PPID} + +@end itemize + +When a simple command other than a builtin or shell function +is to be executed, it +is invoked in a separate execution environment that consists of +the following. Unless otherwise noted, the values are inherited +from the shell. + +@itemize @bullet +@item +the shell's open files, plus any modifications and additions specified +by redirections to the command + +@item +the current working directory + +@item +the file creation mode mask + +@item +shell variables and functions marked for export, along with variables +exported for the command, passed in the environment (@pxref{Environment}) + +@item +traps caught by the shell are reset to the values inherited from the +shell's parent, and traps ignored by the shell are ignored + +@end itemize + +A command invoked in this separate environment cannot affect the +shell's execution environment. + +Command substitution, commands grouped with parentheses, +and asynchronous commands are invoked in a +subshell environment that is a duplicate of the shell environment, +except that traps caught by the shell are reset to the values +that the shell inherited from its parent at invocation. Builtin +commands that are invoked as part of a pipeline are also executed +in a subshell environment. Changes made to the subshell environment +cannot affect the shell's execution environment. + +If a command is followed by a @samp{&} and job control is not active, the +default standard input for the command is the empty file @file{/dev/null}. +Otherwise, the invoked command inherits the file descriptors of the calling +shell as modified by redirections. + +@node Environment +@subsection Environment +@cindex environment + +When a program is invoked it is given an array of strings +called the @var{environment}. +This is a list of name-value pairs, of the form @code{name=value}. + +Bash provides several ways to manipulate the environment. +On invocation, the shell scans its own environment and +creates a parameter for each name found, automatically marking +it for @var{export} +to child processes. Executed commands inherit the environment. +The @code{export} and @samp{declare -x} +commands allow parameters and functions to be added to and +deleted from the environment. If the value of a parameter +in the environment is modified, the new value becomes part +of the environment, replacing the old. The environment +inherited by any executed command consists of the shell's +initial environment, whose values may be modified in the shell, +less any pairs removed by the @code{unset} and @samp{export -n} +commands, plus any additions via the @code{export} and +@samp{declare -x} commands. + +The environment for any simple command +or function may be augmented temporarily by prefixing it with +parameter assignments, as described in @ref{Shell Parameters}. +These assignment statements affect only the environment seen +by that command. + +If the @option{-k} option is set (@pxref{The Set Builtin}), then all +parameter assignments are placed in the environment for a command, +not just those that precede the command name. + +When Bash invokes an external command, the variable @samp{$_} +is set to the full path name of the command and passed to that +command in its environment. + +@node Exit Status +@subsection Exit Status +@cindex exit status + +For the shell's purposes, a command which exits with a +zero exit status has succeeded. +A non-zero exit status indicates failure. +This seemingly counter-intuitive scheme is used so there +is one well-defined way to indicate success and a variety of +ways to indicate various failure modes. +When a command terminates on a fatal signal whose number is @var{N}, +Bash uses the value 128+@var{N} as the exit status. + +If a command is not found, the child process created to +execute it returns a status of 127. If a command is found +but is not executable, the return status is 126. + +If a command fails because of an error during expansion or redirection, +the exit status is greater than zero. + +The exit status is used by the Bash conditional commands +(@pxref{Conditional Constructs}) and some of the list +constructs (@pxref{Lists}). + +All of the Bash builtins return an exit status of zero if they succeed +and a non-zero status on failure, so they may be used by the +conditional and list constructs. +All builtins return an exit status of 2 to indicate incorrect usage. + +@node Signals +@subsection Signals +@cindex signal handling + +When Bash is interactive, in the absence of any traps, it ignores +@code{SIGTERM} (so that @samp{kill 0} does not kill an interactive shell), +and @code{SIGINT} +is caught and handled (so that the @code{wait} builtin is interruptible). +When Bash receives a @code{SIGINT}, it breaks out of any executing loops. +In all cases, Bash ignores @code{SIGQUIT}. +If job control is in effect (@pxref{Job Control}), Bash +ignores @code{SIGTTIN}, @code{SIGTTOU}, and @code{SIGTSTP}. + +Non-builtin commands started by Bash have signal handlers set to the +values inherited by the shell from its parent. +When job control is not in effect, asynchronous commands +ignore @code{SIGINT} and @code{SIGQUIT} in addition to these inherited +handlers. +Commands run as a result of +command substitution ignore the keyboard-generated job control signals +@code{SIGTTIN}, @code{SIGTTOU}, and @code{SIGTSTP}. + +The shell exits by default upon receipt of a @code{SIGHUP}. +Before exiting, an interactive shell resends the @code{SIGHUP} to +all jobs, running or stopped. +Stopped jobs are sent @code{SIGCONT} to ensure that they receive +the @code{SIGHUP}. +To prevent the shell from sending the @code{SIGHUP} signal to a +particular job, it should be removed +from the jobs table with the @code{disown} +builtin (@pxref{Job Control Builtins}) or marked +to not receive @code{SIGHUP} using @code{disown -h}. + +If the @code{huponexit} shell option has been set with @code{shopt} +(@pxref{The Shopt Builtin}), Bash sends a @code{SIGHUP} to all jobs when +an interactive login shell exits. + +If Bash is waiting for a command to complete and receives a signal +for which a trap has been set, the trap will not be executed until +the command completes. +When Bash is waiting for an asynchronous +command via the @code{wait} builtin, the reception of a signal for +which a trap has been set will cause the @code{wait} builtin to return +immediately with an exit status greater than 128, immediately after +which the trap is executed. + +@node Shell Scripts +@section Shell Scripts +@cindex shell script + +A shell script is a text file containing shell commands. When such +a file is used as the first non-option argument when invoking Bash, +and neither the @option{-c} nor @option{-s} option is supplied +(@pxref{Invoking Bash}), +Bash reads and executes commands from the file, then exits. This +mode of operation creates a non-interactive shell. The shell first +searches for the file in the current directory, and looks in the +directories in @env{$PATH} if not found there. + +When Bash runs +a shell script, it sets the special parameter @code{0} to the name +of the file, rather than the name of the shell, and the positional +parameters are set to the remaining arguments, if any are given. +If no additional arguments are supplied, the positional parameters +are unset. + +A shell script may be made executable by using the @code{chmod} command +to turn on the execute bit. When Bash finds such a file while +searching the @env{$PATH} for a command, it spawns a subshell to +execute it. In other words, executing +@example +filename @var{arguments} +@end example +@noindent +is equivalent to executing +@example +bash filename @var{arguments} +@end example + +@noindent +if @code{filename} is an executable shell script. +This subshell reinitializes itself, so that the effect is as if a +new shell had been invoked to interpret the script, with the +exception that the locations of commands remembered by the parent +(see the description of @code{hash} in @ref{Bourne Shell Builtins}) +are retained by the child. + +Most versions of Unix make this a part of the operating system's command +execution mechanism. If the first line of a script begins with +the two characters @samp{#!}, the remainder of the line specifies +an interpreter for the program. +Thus, you can specify Bash, @code{awk}, Perl, or some other +interpreter and write the rest of the script file in that language. + +The arguments to the interpreter +consist of a single optional argument following the interpreter +name on the first line of the script file, followed by the name of +the script file, followed by the rest of the arguments. Bash +will perform this action on operating systems that do not handle it +themselves. Note that some older versions of Unix limit the interpreter +name and argument to a maximum of 32 characters. + +Bash scripts often begin with @code{#! /bin/bash} (assuming that +Bash has been installed in @file{/bin}), since this ensures that +Bash will be used to interpret the script, even if it is executed +under another shell. + +@node Shell Builtin Commands +@chapter Shell Builtin Commands + +@menu +* Bourne Shell Builtins:: Builtin commands inherited from the Bourne + Shell. +* Bash Builtins:: Table of builtins specific to Bash. +* Modifying Shell Behavior:: Builtins to modify shell attributes and + optional behavior. +* Special Builtins:: Builtin commands classified specially by + POSIX. +@end menu + +Builtin commands are contained within the shell itself. +When the name of a builtin command is used as the first word of +a simple command (@pxref{Simple Commands}), the shell executes +the command directly, without invoking another program. +Builtin commands are necessary to implement functionality impossible +or inconvenient to obtain with separate utilities. + +This section briefly describes the builtins which Bash inherits from +the Bourne Shell, as well as the builtin commands which are unique +to or have been extended in Bash. + +Several builtin commands are described in other chapters: builtin +commands which provide the Bash interface to the job control +facilities (@pxref{Job Control Builtins}), the directory stack +(@pxref{Directory Stack Builtins}), the command history +(@pxref{Bash History Builtins}), and the programmable completion +facilities (@pxref{Programmable Completion Builtins}). + +Many of the builtins have been extended by @sc{posix} or Bash. + +Unless otherwise noted, each builtin command documented as accepting +options preceded by @samp{-} accepts @samp{--} +to signify the end of the options. +For example, the @code{:}, @code{true}, @code{false}, and @code{test} +builtins do not accept options. + +@node Bourne Shell Builtins +@section Bourne Shell Builtins + +The following shell builtin commands are inherited from the Bourne Shell. +These commands are implemented as specified by the @sc{posix} standard. + +@table @code +@item : @r{(a colon)} +@btindex : +@example +: [@var{arguments}] +@end example +Do nothing beyond expanding @var{arguments} and performing redirections. +The return status is zero. + +@item . @r{(a period)} +@btindex . +@example +. @var{filename} [@var{arguments}] +@end example +Read and execute commands from the @var{filename} argument in the +current shell context. If @var{filename} does not contain a slash, +the @env{PATH} variable is used to find @var{filename}. +When Bash is not in @sc{posix} mode, the current directory is searched +if @var{filename} is not found in @env{$PATH}. +If any @var{arguments} are supplied, they become the positional +parameters when @var{filename} is executed. Otherwise the positional +parameters are unchanged. +The return status is the exit status of the last command executed, or +zero if no commands are executed. If @var{filename} is not found, or +cannot be read, the return status is non-zero. +This builtin is equivalent to @code{source}. + +@item break +@btindex break +@example +break [@var{n}] +@end example +Exit from a @code{for}, @code{while}, @code{until}, or @code{select} loop. +If @var{n} is supplied, the @var{n}th enclosing loop is exited. +@var{n} must be greater than or equal to 1. +The return status is zero unless @var{n} is not greater than or equal to 1. + +@item cd +@btindex cd +@example +cd [-L|-P] [@var{directory}] +@end example +Change the current working directory to @var{directory}. +If @var{directory} is not given, the value of the @env{HOME} shell +variable is used. +If the shell variable @env{CDPATH} exists, it is used as a search path. +If @var{directory} begins with a slash, @env{CDPATH} is not used. + +The @option{-P} option means to not follow symbolic links; symbolic +links are followed by default or with the @option{-L} option. +If @var{directory} is @samp{-}, it is equivalent to @env{$OLDPWD}. + +If a non-empty directory name from @env{CDPATH} is used, or if +@samp{-} is the first argument, and the directory change is +successful, the absolute pathname of the new working directory is +written to the standard output. + +The return status is zero if the directory is successfully changed, +non-zero otherwise. + +@item continue +@btindex continue +@example +continue [@var{n}] +@end example +Resume the next iteration of an enclosing @code{for}, @code{while}, +@code{until}, or @code{select} loop. +If @var{n} is supplied, the execution of the @var{n}th enclosing loop +is resumed. +@var{n} must be greater than or equal to 1. +The return status is zero unless @var{n} is not greater than or equal to 1. + +@item eval +@btindex eval +@example +eval [@var{arguments}] +@end example +The arguments are concatenated together into a single command, which is +then read and executed, and its exit status returned as the exit status +of @code{eval}. +If there are no arguments or only empty arguments, the return status is +zero. + +@item exec +@btindex exec +@example +exec [-cl] [-a @var{name}] [@var{command} [@var{arguments}]] +@end example +If @var{command} +is supplied, it replaces the shell without creating a new process. +If the @option{-l} option is supplied, the shell places a dash at the +beginning of the zeroth argument passed to @var{command}. +This is what the @code{login} program does. +The @option{-c} option causes @var{command} to be executed with an empty +environment. +If @option{-a} is supplied, the shell passes @var{name} as the zeroth +argument to @var{command}. +If no @var{command} is specified, redirections may be used to affect +the current shell environment. If there are no redirection errors, the +return status is zero; otherwise the return status is non-zero. + +@item exit +@btindex exit +@example +exit [@var{n}] +@end example +Exit the shell, returning a status of @var{n} to the shell's parent. +If @var{n} is omitted, the exit status is that of the last command executed. +Any trap on @code{EXIT} is executed before the shell terminates. + +@item export +@btindex export +@example +export [-fn] [-p] [@var{name}[=@var{value}]] +@end example +Mark each @var{name} to be passed to child processes +in the environment. If the @option{-f} option is supplied, the @var{name}s +refer to shell functions; otherwise the names refer to shell variables. +The @option{-n} option means to no longer mark each @var{name} for export. +If no @var{names} are supplied, or if the @option{-p} option is given, a +list of exported names is displayed. +The @option{-p} option displays output in a form that may be reused as input. +If a variable name is followed by =@var{value}, the value of +the variable is set to @var{value}. + +The return status is zero unless an invalid option is supplied, one of +the names is not a valid shell variable name, or @option{-f} is supplied +with a name that is not a shell function. + +@item getopts +@btindex getopts +@example +getopts @var{optstring} @var{name} [@var{args}] +@end example +@code{getopts} is used by shell scripts to parse positional parameters. +@var{optstring} contains the option characters to be recognized; if a +character is followed by a colon, the option is expected to have an +argument, which should be separated from it by white space. +The colon (@samp{:}) and question mark (@samp{?}) may not be +used as option characters. +Each time it is invoked, @code{getopts} +places the next option in the shell variable @var{name}, initializing +@var{name} if it does not exist, +and the index of the next argument to be processed into the +variable @env{OPTIND}. +@env{OPTIND} is initialized to 1 each time the shell or a shell script +is invoked. +When an option requires an argument, +@code{getopts} places that argument into the variable @env{OPTARG}. +The shell does not reset @env{OPTIND} automatically; it must be manually +reset between multiple calls to @code{getopts} within the same shell +invocation if a new set of parameters is to be used. + +When the end of options is encountered, @code{getopts} exits with a +return value greater than zero. +@env{OPTIND} is set to the index of the first non-option argument, +and @code{name} is set to @samp{?}. + +@code{getopts} +normally parses the positional parameters, but if more arguments are +given in @var{args}, @code{getopts} parses those instead. + +@code{getopts} can report errors in two ways. If the first character of +@var{optstring} is a colon, @var{silent} +error reporting is used. In normal operation diagnostic messages +are printed when invalid options or missing option arguments are +encountered. +If the variable @env{OPTERR} +is set to 0, no error messages will be displayed, even if the first +character of @code{optstring} is not a colon. + +If an invalid option is seen, +@code{getopts} places @samp{?} into @var{name} and, if not silent, +prints an error message and unsets @env{OPTARG}. +If @code{getopts} is silent, the option character found is placed in +@env{OPTARG} and no diagnostic message is printed. + +If a required argument is not found, and @code{getopts} +is not silent, a question mark (@samp{?}) is placed in @var{name}, +@code{OPTARG} is unset, and a diagnostic message is printed. +If @code{getopts} is silent, then a colon (@samp{:}) is placed in +@var{name} and @env{OPTARG} is set to the option character found. + +@item hash +@btindex hash +@example +hash [-r] [-p @var{filename}] [-dt] [@var{name}] +@end example +Remember the full pathnames of commands specified as @var{name} arguments, +so they need not be searched for on subsequent invocations. +The commands are found by searching through the directories listed in +@env{$PATH}. +The @option{-p} option inhibits the path search, and @var{filename} is +used as the location of @var{name}. +The @option{-r} option causes the shell to forget all remembered locations. +The @option{-d} option causes the shell to forget the remembered location +of each @var{name}. +If the @option{-t} option is supplied, the full pathname to which each +@var{name} corresponds is printed. If multiple @var{name} arguments are +supplied with @option{-t} the @var{name} is printed before the hashed +full pathname. +The @option{-l} option causes output to be displayed in a format +that may be reused as input. +If no arguments are given, or if only @option{-l} is supplied, +information about remembered commands is printed. +The return status is zero unless a @var{name} is not found or an invalid +option is supplied. + +@item pwd +@btindex pwd +@example +pwd [-LP] +@end example +Print the absolute pathname of the current working directory. +If the @option{-P} option is supplied, the pathname printed will not +contain symbolic links. +If the @option{-L} option is supplied, the pathname printed may contain +symbolic links. +The return status is zero unless an error is encountered while +determining the name of the current directory or an invalid option +is supplied. + +@item readonly +@btindex readonly +@example +readonly [-apf] [@var{name}[=@var{value}]] @dots{} +@end example +Mark each @var{name} as readonly. +The values of these names may not be changed by subsequent assignment. +If the @option{-f} option is supplied, each @var{name} refers to a shell +function. +The @option{-a} option means each @var{name} refers to an array variable. +If no @var{name} arguments are given, or if the @option{-p} +option is supplied, a list of all readonly names is printed. +The @option{-p} option causes output to be displayed in a format that +may be reused as input. +If a variable name is followed by =@var{value}, the value of +the variable is set to @var{value}. +The return status is zero unless an invalid option is supplied, one of +the @var{name} arguments is not a valid shell variable or function name, +or the @option{-f} option is supplied with a name that is not a shell function. + +@item return +@btindex return +@example +return [@var{n}] +@end example +Cause a shell function to exit with the return value @var{n}. +If @var{n} is not supplied, the return value is the exit status of the +last command executed in the function. +This may also be used to terminate execution of a script being executed +with the @code{.} (or @code{source}) builtin, returning either @var{n} or +the exit status of the last command executed within the script as the exit +status of the script. +Any command associated with the @code{RETURN} trap is executed +before execution resumes after the function or script. +The return status is non-zero if @code{return} is used outside a function +and not during the execution of a script by @code{.} or @code{source}. + +@item shift +@btindex shift +@example +shift [@var{n}] +@end example +Shift the positional parameters to the left by @var{n}. +The positional parameters from @var{n}+1 @dots{} @code{$#} are +renamed to @code{$1} @dots{} @code{$#}-@var{n}. +Parameters represented by the numbers @code{$#} to @code{$#}-@var{n}+1 +are unset. +@var{n} must be a non-negative number less than or equal to @code{$#}. +If @var{n} is zero or greater than @code{$#}, the positional parameters +are not changed. +If @var{n} is not supplied, it is assumed to be 1. +The return status is zero unless @var{n} is greater than @code{$#} or +less than zero, non-zero otherwise. + +@item test +@itemx [ +@btindex test +@btindex [ +Evaluate a conditional expression @var{expr}. +Each operator and operand must be a separate argument. +Expressions are composed of the primaries described below in +@ref{Bash Conditional Expressions}. +@code{test} does not accept any options, nor does it accept and ignore +an argument of @option{--} as signifying the end of options. + +When the @code{[} form is used, the last argument to the command must +be a @code{]}. + +Expressions may be combined using the following operators, listed in +decreasing order of precedence. + +@table @code +@item ! @var{expr} +True if @var{expr} is false. + +@item ( @var{expr} ) +Returns the value of @var{expr}. +This may be used to override the normal precedence of operators. + +@item @var{expr1} -a @var{expr2} +True if both @var{expr1} and @var{expr2} are true. + +@item @var{expr1} -o @var{expr2} +True if either @var{expr1} or @var{expr2} is true. +@end table + +The @code{test} and @code{[} builtins evaluate conditional +expressions using a set of rules based on the number of arguments. + +@table @asis +@item 0 arguments +The expression is false. + +@item 1 argument +The expression is true if and only if the argument is not null. + +@item 2 arguments +If the first argument is @samp{!}, the expression is true if and +only if the second argument is null. +If the first argument is one of the unary conditional operators +(@pxref{Bash Conditional Expressions}), the expression +is true if the unary test is true. +If the first argument is not a valid unary operator, the expression is +false. + +@item 3 arguments +If the second argument is one of the binary conditional +operators (@pxref{Bash Conditional Expressions}), the +result of the expression is the result of the binary test using the +first and third arguments as operands. +If the first argument is @samp{!}, the value is the negation of +the two-argument test using the second and third arguments. +If the first argument is exactly @samp{(} and the third argument is +exactly @samp{)}, the result is the one-argument test of the second +argument. +Otherwise, the expression is false. +The @samp{-a} and @samp{-o} operators are considered binary operators +in this case. + +@item 4 arguments +If the first argument is @samp{!}, the result is the negation of +the three-argument expression composed of the remaining arguments. +Otherwise, the expression is parsed and evaluated according to +precedence using the rules listed above. + +@item 5 or more arguments +The expression is parsed and evaluated according to precedence +using the rules listed above. +@end table + +@item times +@btindex times +@example +times +@end example +Print out the user and system times used by the shell and its children. +The return status is zero. + +@item trap +@btindex trap +@example +trap [-lp] [@var{arg}] [@var{sigspec} @dots{}] +@end example +The commands in @var{arg} are to be read and executed when the +shell receives signal @var{sigspec}. If @var{arg} is absent (and +there is a single @var{sigspec}) or +equal to @samp{-}, each specified signal's disposition is reset +to the value it had when the shell was started. +If @var{arg} is the null string, then the signal specified by +each @var{sigspec} is ignored by the shell and commands it invokes. +If @var{arg} is not present and @option{-p} has been supplied, +the shell displays the trap commands associated with each @var{sigspec}. +If no arguments are supplied, or +only @option{-p} is given, @code{trap} prints the list of commands +associated with each signal number in a form that may be reused as +shell input. +The @option{-l} option causes the shell to print a list of signal names +and their corresponding numbers. +Each @var{sigspec} is either a signal name or a signal number. +Signal names are case insensitive and the @code{SIG} prefix is optional. +If a @var{sigspec} +is @code{0} or @code{EXIT}, @var{arg} is executed when the shell exits. +If a @var{sigspec} is @code{DEBUG}, the command @var{arg} is executed +before every simple command, @code{for} command, @code{case} command, +@code{select} command, every arithmetic @code{for} command, and before +the first command executes in a shell function. +Refer to the description of the @code{extglob} option to the +@code{shopt} builtin (@pxref{The Shopt Builtin}) for details of its +effect on the @code{DEBUG} trap. +If a @var{sigspec} is @code{ERR}, the command @var{arg} +is executed whenever a simple command has a non-zero exit status, +subject to the following conditions. +The @code{ERR} trap is not executed if the failed command is part of the +command list immediately following an @code{until} or @code{while} keyword, +part of the test in an @code{if} statement, +part of a @code{&&} or @code{||} list, or if the command's return +status is being inverted using @code{!}. +These are the same conditions obeyed by the @code{errexit} option. +If a @var{sigspec} is @code{RETURN}, the command @var{arg} is executed +each time a shell function or a script executed with the @code{.} or +@code{source} builtins finishes executing. + +Signals ignored upon entry to the shell cannot be trapped or reset. +Trapped signals that are not being ignored are reset to their original +values in a child process when it is created. + +The return status is zero unless a @var{sigspec} does not specify a +valid signal. + +@item umask +@btindex umask +@example +umask [-p] [-S] [@var{mode}] +@end example +Set the shell process's file creation mask to @var{mode}. If +@var{mode} begins with a digit, it is interpreted as an octal number; +if not, it is interpreted as a symbolic mode mask similar +to that accepted by the @code{chmod} command. If @var{mode} is +omitted, the current value of the mask is printed. If the @option{-S} +option is supplied without a @var{mode} argument, the mask is printed +in a symbolic format. +If the @option{-p} option is supplied, and @var{mode} +is omitted, the output is in a form that may be reused as input. +The return status is zero if the mode is successfully changed or if +no @var{mode} argument is supplied, and non-zero otherwise. + +Note that when the mode is interpreted as an octal number, each number +of the umask is subtracted from @code{7}. Thus, a umask of @code{022} +results in permissions of @code{755}. + +@item unset +@btindex unset +@example +unset [-fv] [@var{name}] +@end example +Each variable or function @var{name} is removed. +If no options are supplied, or the @option{-v} option is given, each +@var{name} refers to a shell variable. +If the @option{-f} option is given, the @var{name}s refer to shell +functions, and the function definition is removed. +Readonly variables and functions may not be unset. +The return status is zero unless a @var{name} is readonly. +@end table + +@node Bash Builtins +@section Bash Builtin Commands + +This section describes builtin commands which are unique to +or have been extended in Bash. +Some of these commands are specified in the @sc{posix} standard. + +@table @code + +@item alias +@btindex alias +@example +alias [@code{-p}] [@var{name}[=@var{value}] @dots{}] +@end example + +Without arguments or with the @option{-p} option, @code{alias} prints +the list of aliases on the standard output in a form that allows +them to be reused as input. +If arguments are supplied, an alias is defined for each @var{name} +whose @var{value} is given. If no @var{value} is given, the name +and value of the alias is printed. +Aliases are described in @ref{Aliases}. + +@item bind +@btindex bind +@example +bind [-m @var{keymap}] [-lpsvPSV] +bind [-m @var{keymap}] [-q @var{function}] [-u @var{function}] [-r @var{keyseq}] +bind [-m @var{keymap}] -f @var{filename} +bind [-m @var{keymap}] -x @var{keyseq:shell-command} +bind [-m @var{keymap}] @var{keyseq:function-name} +bind @var{readline-command} +@end example + +Display current Readline (@pxref{Command Line Editing}) +key and function bindings, +bind a key sequence to a Readline function or macro, +or set a Readline variable. +Each non-option argument is a command as it would appear in a +Readline initialization file (@pxref{Readline Init File}), +but each binding or command must be passed as a separate argument; e.g., +@samp{"\C-x\C-r":re-read-init-file}. +Options, if supplied, have the following meanings: + +@table @code +@item -m @var{keymap} +Use @var{keymap} as the keymap to be affected by +the subsequent bindings. Acceptable @var{keymap} +names are +@code{emacs}, +@code{emacs-standard}, +@code{emacs-meta}, +@code{emacs-ctlx}, +@code{vi}, +@code{vi-move}, +@code{vi-command}, and +@code{vi-insert}. +@code{vi} is equivalent to @code{vi-command}; +@code{emacs} is equivalent to @code{emacs-standard}. + +@item -l +List the names of all Readline functions. + +@item -p +Display Readline function names and bindings in such a way that they +can be used as input or in a Readline initialization file. + +@item -P +List current Readline function names and bindings. + +@item -v +Display Readline variable names and values in such a way that they +can be used as input or in a Readline initialization file. + +@item -V +List current Readline variable names and values. + +@item -s +Display Readline key sequences bound to macros and the strings they output +in such a way that they can be used as input or in a Readline +initialization file. + +@item -S +Display Readline key sequences bound to macros and the strings they output. + +@item -f @var{filename} +Read key bindings from @var{filename}. + +@item -q @var{function} +Query about which keys invoke the named @var{function}. + +@item -u @var{function} +Unbind all keys bound to the named @var{function}. + +@item -r @var{keyseq} +Remove any current binding for @var{keyseq}. + +@item -x @var{keyseq:shell-command} +Cause @var{shell-command} to be executed whenever @var{keyseq} is +entered. + +@end table + +@noindent +The return status is zero unless an invalid option is supplied or an +error occurs. + +@item builtin +@btindex builtin +@example +builtin [@var{shell-builtin} [@var{args}]] +@end example +Run a shell builtin, passing it @var{args}, and return its exit status. +This is useful when defining a shell function with the same +name as a shell builtin, retaining the functionality of the builtin within +the function. +The return status is non-zero if @var{shell-builtin} is not a shell +builtin command. + +@item caller +@btindex caller +@example +caller [@var{expr}] +@end example +Returns the context of any active subroutine call (a shell function or +a script executed with the @code{.} or @code{source} builtins). + +Without @var{expr}, @code{caller} displays the line number and source +filename of the current subroutine call. +If a non-negative integer is supplied as @var{expr}, @code{caller} +displays the line number, subroutine name, and source file corresponding +to that position in the current execution call stack. This extra +information may be used, for example, to print a stack trace. The +current frame is frame 0. + +The return value is 0 unless the shell is not executing a subroutine +call or @var{expr} does not correspond to a valid position in the +call stack. + +@item command +@btindex command +@example +command [-pVv] @var{command} [@var{arguments} @dots{}] +@end example +Runs @var{command} with @var{arguments} ignoring any shell function +named @var{command}. +Only shell builtin commands or commands found by searching the +@env{PATH} are executed. +If there is a shell function named @code{ls}, running @samp{command ls} +within the function will execute the external command @code{ls} +instead of calling the function recursively. +The @option{-p} option means to use a default value for @env{PATH} +that is guaranteed to find all of the standard utilities. +The return status in this case is 127 if @var{command} cannot be +found or an error occurred, and the exit status of @var{command} +otherwise. + +If either the @option{-V} or @option{-v} option is supplied, a +description of @var{command} is printed. The @option{-v} option +causes a single word indicating the command or file name used to +invoke @var{command} to be displayed; the @option{-V} option produces +a more verbose description. In this case, the return status is +zero if @var{command} is found, and non-zero if not. + +@item declare +@btindex declare +@example +declare [-afFirtx] [-p] [@var{name}[=@var{value}] @dots{}] +@end example + +Declare variables and give them attributes. If no @var{name}s +are given, then display the values of variables instead. + +The @option{-p} option will display the attributes and values of each +@var{name}. +When @option{-p} is used, additional options are ignored. +The @option{-F} option inhibits the display of function definitions; +only the function name and attributes are printed. +If the @code{extdebug} shell option is enabled using @code{shopt} +(@pxref{The Shopt Builtin}), the source file name and line number where +the function is defined are displayed as well. +@option{-F} implies @option{-f}. +The following options can be used to restrict output to variables with +the specified attributes or to give variables attributes: + +@table @code +@item -a +Each @var{name} is an array variable (@pxref{Arrays}). + +@item -f +Use function names only. + +@item -i +The variable is to be treated as +an integer; arithmetic evaluation (@pxref{Shell Arithmetic}) is +performed when the variable is assigned a value. + +@item -r +Make @var{name}s readonly. These names cannot then be assigned values +by subsequent assignment statements or unset. + +@item -t +Give each @var{name} the @code{trace} attribute. +Traced functions inherit the @code{DEBUG} and @code{RETURN} traps from +the calling shell. +The trace attribute has no special meaning for variables. + +@item -x +Mark each @var{name} for export to subsequent commands via +the environment. +@end table + +Using @samp{+} instead of @samp{-} turns off the attribute instead, +with the exceptions that @samp{+a} +may not be used to destroy an array variable and @samp{+r} will not +remove the readonly attribute. +When used in a function, @code{declare} makes each @var{name} local, +as with the @code{local} command. If a variable name is followed by +=@var{value}, the value of the variable is set to @var{value}. + +The return status is zero unless an invalid option is encountered, +an attempt is made to define a function using @samp{-f foo=bar}, +an attempt is made to assign a value to a readonly variable, +an attempt is made to assign a value to an array variable without +using the compound assignment syntax (@pxref{Arrays}), +one of the @var{names} is not a valid shell variable name, +an attempt is made to turn off readonly status for a readonly variable, +an attempt is made to turn off array status for an array variable, +or an attempt is made to display a non-existent function with @option{-f}. + +@item echo +@btindex echo +@example +echo [-neE] [@var{arg} @dots{}] +@end example +Output the @var{arg}s, separated by spaces, terminated with a +newline. +The return status is always 0. +If @option{-n} is specified, the trailing newline is suppressed. +If the @option{-e} option is given, interpretation of the following +backslash-escaped characters is enabled. +The @option{-E} option disables the interpretation of these escape characters, +even on systems where they are interpreted by default. +The @code{xpg_echo} shell option may be used to +dynamically determine whether or not @code{echo} expands these +escape characters by default. +@code{echo} does not interpret @option{--} to mean the end of options. + +@code{echo} interprets the following escape sequences: +@table @code +@item \a +alert (bell) +@item \b +backspace +@item \c +suppress trailing newline +@item \e +escape +@item \f +form feed +@item \n +new line +@item \r +carriage return +@item \t +horizontal tab +@item \v +vertical tab +@item \\ +backslash +@item \0@var{nnn} +the eight-bit character whose value is the octal value @var{nnn} +(zero to three octal digits) +@item \x@var{HH} +the eight-bit character whose value is the hexadecimal value @var{HH} +(one or two hex digits) +@end table + +@item enable +@btindex enable +@example +enable [-a] [-dnps] [-f @var{filename}] [@var{name} @dots{}] +@end example +Enable and disable builtin shell commands. +Disabling a builtin allows a disk command which has the same name +as a shell builtin to be executed without specifying a full pathname, +even though the shell normally searches for builtins before disk commands. +If @option{-n} is used, the @var{name}s become disabled. Otherwise +@var{name}s are enabled. For example, to use the @code{test} binary +found via @env{$PATH} instead of the shell builtin version, type +@samp{enable -n test}. + +If the @option{-p} option is supplied, or no @var{name} arguments appear, +a list of shell builtins is printed. With no other arguments, the list +consists of all enabled shell builtins. +The @option{-a} option means to list +each builtin with an indication of whether or not it is enabled. + +The @option{-f} option means to load the new builtin command @var{name} +from shared object @var{filename}, on systems that support dynamic loading. +The @option{-d} option will delete a builtin loaded with @option{-f}. + +If there are no options, a list of the shell builtins is displayed. +The @option{-s} option restricts @code{enable} to the @sc{posix} special +builtins. If @option{-s} is used with @option{-f}, the new builtin becomes +a special builtin (@pxref{Special Builtins}). + +The return status is zero unless a @var{name} is not a shell builtin +or there is an error loading a new builtin from a shared object. + +@item help +@btindex help +@example +help [-s] [@var{pattern}] +@end example +Display helpful information about builtin commands. +If @var{pattern} is specified, @code{help} gives detailed help +on all commands matching @var{pattern}, otherwise a list of +the builtins is printed. +The @option{-s} option restricts the information displayed to a short +usage synopsis. +The return status is zero unless no command matches @var{pattern}. + +@item let +@btindex let +@example +let @var{expression} [@var{expression}] +@end example +The @code{let} builtin allows arithmetic to be performed on shell +variables. Each @var{expression} is evaluated according to the +rules given below in @ref{Shell Arithmetic}. If the +last @var{expression} evaluates to 0, @code{let} returns 1; +otherwise 0 is returned. + +@item local +@btindex local +@example +local [@var{option}] @var{name}[=@var{value}] @dots{} +@end example +For each argument, a local variable named @var{name} is created, +and assigned @var{value}. +The @var{option} can be any of the options accepted by @code{declare}. +@code{local} can only be used within a function; it makes the variable +@var{name} have a visible scope restricted to that function and its +children. The return status is zero unless @code{local} is used outside +a function, an invalid @var{name} is supplied, or @var{name} is a +readonly variable. + +@item logout +@btindex logout +@example +logout [@var{n}] +@end example +Exit a login shell, returning a status of @var{n} to the shell's +parent. + +@item printf +@btindex printf +@example +@code{printf} [-v @var{var}] @var{format} [@var{arguments}] +@end example +Write the formatted @var{arguments} to the standard output under the +control of the @var{format}. +The @var{format} is a character string which contains three types of objects: +plain characters, which are simply copied to standard output, character +escape sequences, which are converted and copied to the standard output, and +format specifications, each of which causes printing of the next successive +@var{argument}. +In addition to the standard @code{printf(1)} formats, @samp{%b} causes +@code{printf} to expand backslash escape sequences in the corresponding +@var{argument}, +(except that @samp{\c} terminates output, backslashes in +@samp{\'}, @samp{\"}, and @samp{\?} are not removed, and octal escapes +beginning with @samp{\0} may contain up to four digits), +and @samp{%q} causes @code{printf} to output the +corresponding @var{argument} in a format that can be reused as shell input. + +The @option{-v} option causes the output to be assigned to the variable +@var{var} rather than being printed to the standard output. + +The @var{format} is reused as necessary to consume all of the @var{arguments}. +If the @var{format} requires more @var{arguments} than are supplied, the +extra format specifications behave as if a zero value or null string, as +appropriate, had been supplied. The return value is zero on success, +non-zero on failure. + +@item read +@btindex read +@example +read [-ers] [-a @var{aname}] [-d @var{delim}] [-n @var{nchars}] [-p @var{prompt}] [-t @var{timeout}] [-u @var{fd}] [@var{name} @dots{}] +@end example +One line is read from the standard input, or from the file descriptor +@var{fd} supplied as an argument to the @option{-u} option, and the first word +is assigned to the first @var{name}, the second word to the second @var{name}, +and so on, with leftover words and their intervening separators assigned +to the last @var{name}. +If there are fewer words read from the input stream than names, +the remaining names are assigned empty values. +The characters in the value of the @env{IFS} variable +are used to split the line into words. +The backslash character @samp{\} may be used to remove any special +meaning for the next character read and for line continuation. +If no names are supplied, the line read is assigned to the +variable @env{REPLY}. +The return code is zero, unless end-of-file is encountered, @code{read} +times out, or an invalid file descriptor is supplied as the argument to +@option{-u}. +Options, if supplied, have the following meanings: + +@table @code +@item -a @var{aname} +The words are assigned to sequential indices of the array variable +@var{aname}, starting at 0. +All elements are removed from @var{aname} before the assignment. +Other @var{name} arguments are ignored. + +@item -d @var{delim} +The first character of @var{delim} is used to terminate the input line, +rather than newline. + +@item -e +Readline (@pxref{Command Line Editing}) is used to obtain the line. + +@item -n @var{nchars} +@code{read} returns after reading @var{nchars} characters rather than +waiting for a complete line of input. + +@item -p @var{prompt} +Display @var{prompt}, without a trailing newline, before attempting +to read any input. +The prompt is displayed only if input is coming from a terminal. + +@item -r +If this option is given, backslash does not act as an escape character. +The backslash is considered to be part of the line. +In particular, a backslash-newline pair may not be used as a line +continuation. + +@item -s +Silent mode. If input is coming from a terminal, characters are +not echoed. + +@item -t @var{timeout} +Cause @code{read} to time out and return failure if a complete line of +input is not read within @var{timeout} seconds. +This option has no effect if @code{read} is not reading input from the +terminal or a pipe. + +@item -u @var{fd} +Read input from file descriptor @var{fd}. + +@end table + +@item source +@btindex source +@example +source @var{filename} +@end example +A synonym for @code{.} (@pxref{Bourne Shell Builtins}). + +@item type +@btindex type +@example +type [-afptP] [@var{name} @dots{}] +@end example +For each @var{name}, indicate how it would be interpreted if used as a +command name. + +If the @option{-t} option is used, @code{type} prints a single word +which is one of @samp{alias}, @samp{function}, @samp{builtin}, +@samp{file} or @samp{keyword}, +if @var{name} is an alias, shell function, shell builtin, +disk file, or shell reserved word, respectively. +If the @var{name} is not found, then nothing is printed, and +@code{type} returns a failure status. + +If the @option{-p} option is used, @code{type} either returns the name +of the disk file that would be executed, or nothing if @option{-t} +would not return @samp{file}. + +The @option{-P} option forces a path search for each @var{name}, even if +@option{-t} would not return @samp{file}. + +If a command is hashed, @option{-p} and @option{-P} print the hashed value, +not necessarily the file that appears first in @code{$PATH}. + +If the @option{-a} option is used, @code{type} returns all of the places +that contain an executable named @var{file}. +This includes aliases and functions, if and only if the @option{-p} option +is not also used. + +If the @option{-f} option is used, @code{type} does not attempt to find +shell functions, as with the @code{command} builtin. + +The return status is zero if any of the @var{names} are found, non-zero +if none are found. + +@item typeset +@btindex typeset +@example +typeset [-afFrxi] [-p] [@var{name}[=@var{value}] @dots{}] +@end example +The @code{typeset} command is supplied for compatibility with the Korn +shell; however, it has been deprecated in favor of the @code{declare} +builtin command. + +@item ulimit +@btindex ulimit +@example +ulimit [-acdefilmnpqrstuvxSH] [@var{limit}] +@end example +@code{ulimit} provides control over the resources available to processes +started by the shell, on systems that allow such control. If an +option is given, it is interpreted as follows: +@table @code +@item -S +Change and report the soft limit associated with a resource. + +@item -H +Change and report the hard limit associated with a resource. + +@item -a +All current limits are reported. + +@item -c +The maximum size of core files created. + +@item -d +The maximum size of a process's data segment. + +@item -e +The maximum scheduling priority ("nice"). + +@item -f +The maximum size of files written by the shell and its children. + +@item -i +The maximum number of pending signals. + +@item -l +The maximum size that may be locked into memory. + +@item -m +The maximum resident set size. + +@item -n +The maximum number of open file descriptors. + +@item -p +The pipe buffer size. + +@item -q +The maximum number of bytes in POSIX message queues. + +@item -r +The maximum real-time scheduling priority. + +@item -s +The maximum stack size. + +@item -t +The maximum amount of cpu time in seconds. + +@item -u +The maximum number of processes available to a single user. + +@item -v +The maximum amount of virtual memory available to the process. + +@item -x +The maximum number of file locks. + +@end table + +If @var{limit} is given, it is the new value of the specified resource; +the special @var{limit} values @code{hard}, @code{soft}, and +@code{unlimited} stand for the current hard limit, the current soft limit, +and no limit, respectively. +Otherwise, the current value of the soft limit for the specified resource +is printed, unless the @option{-H} option is supplied. +When setting new limits, if neither @option{-H} nor @option{-S} is supplied, +both the hard and soft limits are set. +If no option is given, then @option{-f} is assumed. Values are in 1024-byte +increments, except for @option{-t}, which is in seconds, @option{-p}, +which is in units of 512-byte blocks, and @option{-n} and @option{-u}, which +are unscaled values. + +The return status is zero unless an invalid option or argument is supplied, +or an error occurs while setting a new limit. + +@item unalias +@btindex unalias +@example +unalias [-a] [@var{name} @dots{} ] +@end example + +Remove each @var{name} from the list of aliases. If @option{-a} is +supplied, all aliases are removed. +Aliases are described in @ref{Aliases}. + +@end table + +@node Modifying Shell Behavior +@section Modifying Shell Behavior + +@menu +* The Set Builtin:: Change the values of shell attributes and + positional parameters. +* The Shopt Builtin:: Modify shell optional behavior. +@end menu + +@node The Set Builtin +@subsection The Set Builtin + +This builtin is so complicated that it deserves its own section. @code{set} +allows you to change the values of shell options and set the positional +parameters, or to display the names and values of shell variables. + +@table @code +@item set +@btindex set +@example +set [--abefhkmnptuvxBCEHPT] [-o @var{option}] [@var{argument} @dots{}] +set [+abefhkmnptuvxBCEHPT] [+o @var{option}] [@var{argument} @dots{}] +@end example + +If no options or arguments are supplied, @code{set} displays the names +and values of all shell variables and functions, sorted according to the +current locale, in a format that may be reused as input +for setting or resetting the currently-set variables. +Read-only variables cannot be reset. +In @sc{posix} mode, only shell variables are listed. + +When options are supplied, they set or unset shell attributes. +Options, if specified, have the following meanings: + +@table @code +@item -a +Mark variables and function which are modified or created for export +to the environment of subsequent commands. + +@item -b +Cause the status of terminated background jobs to be reported +immediately, rather than before printing the next primary prompt. + +@item -e +Exit immediately if a simple command (@pxref{Simple Commands}) exits +with a non-zero status, unless the command that fails is part of the +command list immediately following a @code{while} or @code{until} keyword, +part of the test in an @code{if} statement, +part of a @code{&&} or @code{||} list, +any command in a pipeline but the last, +or if the command's return status is being inverted using @code{!}. +A trap on @code{ERR}, if set, is executed before the shell exits. + +@item -f +Disable file name generation (globbing). + +@item -h +Locate and remember (hash) commands as they are looked up for execution. +This option is enabled by default. + +@item -k +All arguments in the form of assignment statements are placed +in the environment for a command, not just those that precede +the command name. + +@item -m +Job control is enabled (@pxref{Job Control}). + +@item -n +Read commands but do not execute them; this may be used to check a +script for syntax errors. +This option is ignored by interactive shells. + +@item -o @var{option-name} + +Set the option corresponding to @var{option-name}: + +@table @code +@item allexport +Same as @code{-a}. + +@item braceexpand +Same as @code{-B}. + +@item emacs +Use an @code{emacs}-style line editing interface (@pxref{Command Line Editing}). + +@item errexit +Same as @code{-e}. + +@item errtrace +Same as @code{-E}. + +@item functrace +Same as @code{-T}. + +@item hashall +Same as @code{-h}. + +@item histexpand +Same as @code{-H}. + +@item history +Enable command history, as described in @ref{Bash History Facilities}. +This option is on by default in interactive shells. + +@item ignoreeof +An interactive shell will not exit upon reading EOF. + +@item keyword +Same as @code{-k}. + +@item monitor +Same as @code{-m}. + +@item noclobber +Same as @code{-C}. + +@item noexec +Same as @code{-n}. + +@item noglob +Same as @code{-f}. + +@item nolog +Currently ignored. + +@item notify +Same as @code{-b}. + +@item nounset +Same as @code{-u}. + +@item onecmd +Same as @code{-t}. + +@item physical +Same as @code{-P}. + +@item pipefail +If set, the return value of a pipeline is the value of the last +(rightmost) command to exit with a non-zero status, or zero if all +commands in the pipeline exit successfully. +This option is disabled by default. + +@item posix +Change the behavior of Bash where the default operation differs +from the @sc{posix} standard to match the standard +(@pxref{Bash POSIX Mode}). +This is intended to make Bash behave as a strict superset of that +standard. + +@item privileged +Same as @code{-p}. + +@item verbose +Same as @code{-v}. + +@item vi +Use a @code{vi}-style line editing interface. + +@item xtrace +Same as @code{-x}. +@end table + +@item -p +Turn on privileged mode. +In this mode, the @env{$BASH_ENV} and @env{$ENV} files are not +processed, shell functions are not inherited from the environment, +and the @env{SHELLOPTS} variable, if it appears in the environment, +is ignored. +If the shell is started with the effective user (group) id not equal to the +real user (group) id, and the @code{-p} option is not supplied, these actions +are taken and the effective user id is set to the real user id. +If the @code{-p} option is supplied at startup, the effective user id is +not reset. +Turning this option off causes the effective user +and group ids to be set to the real user and group ids. + +@item -t +Exit after reading and executing one command. + +@item -u +Treat unset variables as an error when performing parameter expansion. +An error message will be written to the standard error, and a non-interactive +shell will exit. + +@item -v +Print shell input lines as they are read. + +@item -x +Print a trace of simple commands, @code{for} commands, @code{case} +commands, @code{select} commands, and arithmetic @code{for} commands +and their arguments or associated word lists after they are +expanded and before they are executed. The value of the @env{PS4} +variable is expanded and the resultant value is printed before +the command and its expanded arguments. + +@item -B +The shell will perform brace expansion (@pxref{Brace Expansion}). +This option is on by default. + +@item -C +Prevent output redirection using @samp{>}, @samp{>&}, and @samp{<>} +from overwriting existing files. + +@item -E +If set, any trap on @code{ERR} is inherited by shell functions, command +substitutions, and commands executed in a subshell environment. +The @code{ERR} trap is normally not inherited in such cases. + +@item -H +Enable @samp{!} style history substitution (@pxref{History Interaction}). +This option is on by default for interactive shells. + +@item -P +If set, do not follow symbolic links when performing commands such as +@code{cd} which change the current directory. The physical directory +is used instead. By default, Bash follows +the logical chain of directories when performing commands +which change the current directory. + +For example, if @file{/usr/sys} is a symbolic link to @file{/usr/local/sys} +then: +@example +$ cd /usr/sys; echo $PWD +/usr/sys +$ cd ..; pwd +/usr +@end example + +@noindent +If @code{set -P} is on, then: +@example +$ cd /usr/sys; echo $PWD +/usr/local/sys +$ cd ..; pwd +/usr/local +@end example + +@item -T +If set, any trap on @code{DEBUG} and @code{RETURN} are inherited by +shell functions, command substitutions, and commands executed +in a subshell environment. +The @code{DEBUG} and @code{RETURN} traps are normally not inherited +in such cases. + +@item -- +If no arguments follow this option, then the positional parameters are +unset. Otherwise, the positional parameters are set to the +@var{arguments}, even if some of them begin with a @samp{-}. + +@item - +Signal the end of options, cause all remaining @var{arguments} +to be assigned to the positional parameters. The @option{-x} +and @option{-v} options are turned off. +If there are no arguments, the positional parameters remain unchanged. +@end table + +Using @samp{+} rather than @samp{-} causes these options to be +turned off. The options can also be used upon invocation of the +shell. The current set of options may be found in @code{$-}. + +The remaining N @var{arguments} are positional parameters and are +assigned, in order, to @code{$1}, @code{$2}, @dots{} @code{$N}. +The special parameter @code{#} is set to N. + +The return status is always zero unless an invalid option is supplied. +@end table + +@node The Shopt Builtin +@subsection The Shopt Builtin + +This builtin allows you to change additional shell optional behavior. + +@table @code + +@item shopt +@btindex shopt +@example +shopt [-pqsu] [-o] [@var{optname} @dots{}] +@end example +Toggle the values of variables controlling optional shell behavior. +With no options, or with the @option{-p} option, a list of all settable +options is displayed, with an indication of whether or not each is set. +The @option{-p} option causes output to be displayed in a form that +may be reused as input. +Other options have the following meanings: + +@table @code +@item -s +Enable (set) each @var{optname}. + +@item -u +Disable (unset) each @var{optname}. + +@item -q +Suppresses normal output; the return status +indicates whether the @var{optname} is set or unset. +If multiple @var{optname} arguments are given with @option{-q}, +the return status is zero if all @var{optnames} are enabled; +non-zero otherwise. + +@item -o +Restricts the values of +@var{optname} to be those defined for the @option{-o} option to the +@code{set} builtin (@pxref{The Set Builtin}). +@end table + +If either @option{-s} or @option{-u} +is used with no @var{optname} arguments, the display is limited to +those options which are set or unset, respectively. + +Unless otherwise noted, the @code{shopt} options are disabled (off) +by default. + +The return status when listing options is zero if all @var{optnames} +are enabled, non-zero otherwise. When setting or unsetting options, +the return status is zero unless an @var{optname} is not a valid shell +option. + +The list of @code{shopt} options is: +@table @code + +@item autocd +If set, a command name that is the name of a directory is executed as if +it were the argument to the @code{cd} command. +This option is only used by interactive shells. + +@item cdable_vars +If this is set, an argument to the @code{cd} builtin command that +is not a directory is assumed to be the name of a variable whose +value is the directory to change to. + +@item cdspell +If set, minor errors in the spelling of a directory component in a +@code{cd} command will be corrected. +The errors checked for are transposed characters, +a missing character, and a character too many. +If a correction is found, the corrected path is printed, +and the command proceeds. +This option is only used by interactive shells. + +@item checkhash +If this is set, Bash checks that a command found in the hash +table exists before trying to execute it. If a hashed command no +longer exists, a normal path search is performed. + +@item checkjobs +If set, Bash lists the status of any stopped and running jobs before +exiting an interactive shell. If any jobs are running, this causes +the exit to be deferred until a second exit is attempted without an +intervening command (@pxref{Job Control}). +The shell always postpones exiting if any jobs are stopped. + +@item checkwinsize +If set, Bash checks the window size after each command +and, if necessary, updates the values of +@env{LINES} and @env{COLUMNS}. + +@item cmdhist +If set, Bash +attempts to save all lines of a multiple-line +command in the same history entry. This allows +easy re-editing of multi-line commands. + +@item dotglob +If set, Bash includes filenames beginning with a `.' in +the results of filename expansion. + +@item execfail +If this is set, a non-interactive shell will not exit if +it cannot execute the file specified as an argument to the @code{exec} +builtin command. An interactive shell does not exit if @code{exec} +fails. + +@item expand_aliases +If set, aliases are expanded as described below under Aliases, +@ref{Aliases}. +This option is enabled by default for interactive shells. + +@item extdebug +If set, behavior intended for use by debuggers is enabled: + +@enumerate +@item +The @option{-F} option to the @code{declare} builtin (@pxref{Bash Builtins}) +displays the source file name and line number corresponding to each function +name supplied as an argument. + +@item +If the command run by the @code{DEBUG} trap returns a non-zero value, the +next command is skipped and not executed. + +@item +If the command run by the @code{DEBUG} trap returns a value of 2, and the +shell is executing in a subroutine (a shell function or a shell script +executed by the @code{.} or @code{source} builtins), a call to +@code{return} is simulated. + +@item +@code{BASH_ARGC} and @code{BASH_ARGV} are updated as described in their +descriptions (@pxref{Bash Variables}). + +@item +Function tracing is enabled: command substitution, shell functions, and +subshells invoked with @code{( @var{command} )} inherit the +@code{DEBUG} and @code{RETURN} traps. + +@item +Error tracing is enabled: command substitution, shell functions, and +subshells invoked with @code{( @var{command} )} inherit the +@code{ERROR} trap. +@end enumerate + +@item extglob +If set, the extended pattern matching features described above +(@pxref{Pattern Matching}) are enabled. + +@item extquote +If set, @code{$'@var{string}'} and @code{$"@var{string}"} quoting is +performed within @code{$@{@var{parameter}@}} expansions +enclosed in double quotes. This option is enabled by default. + +@item failglob +If set, patterns which fail to match filenames during pathname expansion +result in an expansion error. + +@item force_fignore +If set, the suffixes specified by the @env{FIGNORE} shell variable +cause words to be ignored when performing word completion even if +the ignored words are the only possible completions. +@xref{Bash Variables}, for a description of @env{FIGNORE}. +This option is enabled by default. + +@item gnu_errfmt +If set, shell error messages are written in the standard @sc{gnu} error +message format. + +@item histappend +If set, the history list is appended to the file named by the value +of the @env{HISTFILE} +variable when the shell exits, rather than overwriting the file. + +@item histreedit +If set, and Readline +is being used, a user is given the opportunity to re-edit a +failed history substitution. + +@item histverify +If set, and Readline +is being used, the results of history substitution are not immediately +passed to the shell parser. Instead, the resulting line is loaded into +the Readline editing buffer, allowing further modification. + +@item hostcomplete +If set, and Readline is being used, Bash will attempt to perform +hostname completion when a word containing a @samp{@@} is being +completed (@pxref{Commands For Completion}). This option is enabled +by default. + +@item huponexit +If set, Bash will send @code{SIGHUP} to all jobs when an interactive +login shell exits (@pxref{Signals}). + +@item interactive_comments +Allow a word beginning with @samp{#} +to cause that word and all remaining characters on that +line to be ignored in an interactive shell. +This option is enabled by default. + +@item lithist +If enabled, and the @code{cmdhist} +option is enabled, multi-line commands are saved to the history with +embedded newlines rather than using semicolon separators where possible. + +@item login_shell +The shell sets this option if it is started as a login shell +(@pxref{Invoking Bash}). +The value may not be changed. + +@item mailwarn +If set, and a file that Bash is checking for mail has been +accessed since the last time it was checked, the message +@code{"The mail in @var{mailfile} has been read"} is displayed. + +@item no_empty_cmd_completion +If set, and Readline is being used, Bash will not attempt to search +the @env{PATH} for possible completions when completion is attempted +on an empty line. + +@item nocaseglob +If set, Bash matches filenames in a case-insensitive fashion when +performing filename expansion. + +@item nocasematch +If set, Bash matches patterns in a case-insensitive fashion when +performing matching while executing @code{case} or @code{[[} +conditional commands. + +@item nullglob +If set, Bash allows filename patterns which match no +files to expand to a null string, rather than themselves. + +@item progcomp +If set, the programmable completion facilities +(@pxref{Programmable Completion}) are enabled. +This option is enabled by default. + +@item promptvars +If set, prompt strings undergo +parameter expansion, command substitution, arithmetic +expansion, and quote removal after being expanded +as described below (@pxref{Printing a Prompt}). +This option is enabled by default. + +@item restricted_shell +The shell sets this option if it is started in restricted mode +(@pxref{The Restricted Shell}). +The value may not be changed. +This is not reset when the startup files are executed, allowing +the startup files to discover whether or not a shell is restricted. + +@item shift_verbose +If this is set, the @code{shift} +builtin prints an error message when the shift count exceeds the +number of positional parameters. + +@item sourcepath +If set, the @code{source} builtin uses the value of @env{PATH} +to find the directory containing the file supplied as an argument. +This option is enabled by default. + +@item xpg_echo +If set, the @code{echo} builtin expands backslash-escape sequences +by default. + +@end table + +@noindent +The return status when listing options is zero if all @var{optnames} +are enabled, non-zero otherwise. +When setting or unsetting options, the return status is zero unless an +@var{optname} is not a valid shell option. + +@end table + +@node Special Builtins +@section Special Builtins +@cindex special builtin + +For historical reasons, the @sc{posix} standard has classified +several builtin commands as @emph{special}. +When Bash is executing in @sc{posix} mode, the special builtins +differ from other builtin commands in three respects: + +@enumerate +@item +Special builtins are found before shell functions during command lookup. + +@item +If a special builtin returns an error status, a non-interactive shell exits. + +@item +Assignment statements preceding the command stay in effect in the shell +environment after the command completes. +@end enumerate + +When Bash is not executing in @sc{posix} mode, these builtins behave no +differently than the rest of the Bash builtin commands. +The Bash @sc{posix} mode is described in @ref{Bash POSIX Mode}. + +These are the @sc{posix} special builtins: +@example +@w{break : . continue eval exec exit export readonly return set} +@w{shift trap unset} +@end example + +@node Shell Variables +@chapter Shell Variables + +@menu +* Bourne Shell Variables:: Variables which Bash uses in the same way + as the Bourne Shell. +* Bash Variables:: List of variables that exist in Bash. +@end menu + +This chapter describes the shell variables that Bash uses. +Bash automatically assigns default values to a number of variables. + +@node Bourne Shell Variables +@section Bourne Shell Variables + +Bash uses certain shell variables in the same way as the Bourne shell. +In some cases, Bash assigns a default value to the variable. + +@vtable @code + +@item CDPATH +A colon-separated list of directories used as a search path for +the @code{cd} builtin command. + +@item HOME +The current user's home directory; the default for the @code{cd} builtin +command. +The value of this variable is also used by tilde expansion +(@pxref{Tilde Expansion}). + +@item IFS +A list of characters that separate fields; used when the shell splits +words as part of expansion. + +@item MAIL +If this parameter is set to a filename and the @env{MAILPATH} variable +is not set, Bash informs the user of the arrival of mail in +the specified file. + +@item MAILPATH +A colon-separated list of filenames which the shell periodically checks +for new mail. +Each list entry can specify the message that is printed when new mail +arrives in the mail file by separating the file name from the message with +a @samp{?}. +When used in the text of the message, @code{$_} expands to the name of +the current mail file. + +@item OPTARG +The value of the last option argument processed by the @code{getopts} builtin. + +@item OPTIND +The index of the last option argument processed by the @code{getopts} builtin. + +@item PATH +A colon-separated list of directories in which the shell looks for +commands. +A zero-length (null) directory name in the value of @code{PATH} indicates the +current directory. +A null directory name may appear as two adjacent colons, or as an initial +or trailing colon. + + +@item PS1 +The primary prompt string. The default value is @samp{\s-\v\$ }. +@xref{Printing a Prompt}, for the complete list of escape +sequences that are expanded before @env{PS1} is displayed. + +@item PS2 +The secondary prompt string. The default value is @samp{> }. + +@end vtable + +@node Bash Variables +@section Bash Variables + +These variables are set or used by Bash, but other shells +do not normally treat them specially. + +A few variables used by Bash are described in different chapters: +variables for controlling the job control facilities +(@pxref{Job Control Variables}). + +@vtable @code + +@item BASH +The full pathname used to execute the current instance of Bash. + +@item BASHPID +Expands to the process id of the current Bash process. +This differs from @code{$$} under certain circumstances, such as subshells +that do not require Bash to be re-initialized. + +@item BASH_ARGC +An array variable whose values are the number of parameters in each +frame of the current bash execution call stack. The number of +parameters to the current subroutine (shell function or script executed +with @code{.} or @code{source}) is at the top of the stack. When a +subroutine is executed, the number of parameters passed is pushed onto +@code{BASH_ARGC}. +The shell sets @code{BASH_ARGC} only when in extended debugging mode +(see @ref{The Shopt Builtin} +for a description of the @code{extdebug} option to the @code{shopt} +builtin). + +@item BASH_ARGV +An array variable containing all of the parameters in the current bash +execution call stack. The final parameter of the last subroutine call +is at the top of the stack; the first parameter of the initial call is +at the bottom. When a subroutine is executed, the parameters supplied +are pushed onto @code{BASH_ARGV}. +The shell sets @code{BASH_ARGV} only when in extended debugging mode +(see @ref{The Shopt Builtin} +for a description of the @code{extdebug} option to the @code{shopt} +builtin). + +@item BASH_COMMAND +The command currently being executed or about to be executed, unless the +shell is executing a command as the result of a trap, +in which case it is the command executing at the time of the trap. + +@item BASH_ENV +If this variable is set when Bash is invoked to execute a shell +script, its value is expanded and used as the name of a startup file +to read before executing the script. @xref{Bash Startup Files}. + +@item BASH_EXECUTION_STRING +The command argument to the @option{-c} invocation option. + +@item BASH_LINENO +An array variable whose members are the line numbers in source files +corresponding to each member of @var{FUNCNAME}. +@code{$@{BASH_LINENO[$i]@}} is the line number in the source file where +@code{$@{FUNCNAME[$i]@}} was called. +The corresponding source file name is @code{$@{BASH_SOURCE[$i]@}}. +Use @code{LINENO} to obtain the current line number. + +@item BASH_REMATCH +An array variable whose members are assigned by the @samp{=~} binary +operator to the @code{[[} conditional command +(@pxref{Conditional Constructs}). +The element with index 0 is the portion of the string +matching the entire regular expression. +The element with index @var{n} is the portion of the +string matching the @var{n}th parenthesized subexpression. +This variable is read-only. + +@item BASH_SOURCE +An array variable whose members are the source filenames corresponding +to the elements in the @code{FUNCNAME} array variable. + +@item BASH_SUBSHELL +Incremented by one each time a subshell or subshell environment is spawned. +The initial value is 0. + +@item BASH_VERSINFO +A readonly array variable (@pxref{Arrays}) +whose members hold version information for this instance of Bash. +The values assigned to the array members are as follows: + +@table @code + +@item BASH_VERSINFO[0] +The major version number (the @var{release}). + +@item BASH_VERSINFO[1] +The minor version number (the @var{version}). + +@item BASH_VERSINFO[2] +The patch level. + +@item BASH_VERSINFO[3] +The build version. + +@item BASH_VERSINFO[4] +The release status (e.g., @var{beta1}). + +@item BASH_VERSINFO[5] +The value of @env{MACHTYPE}. + +@end table + +@item BASH_VERSION +The version number of the current instance of Bash. + +@item COLUMNS +Used by the @code{select} builtin command to determine the terminal width +when printing selection lists. Automatically set upon receipt of a +@code{SIGWINCH}. + +@item COMP_CWORD +An index into @env{$@{COMP_WORDS@}} of the word containing the current +cursor position. +This variable is available only in shell functions invoked by the +programmable completion facilities (@pxref{Programmable Completion}). + +@item COMP_LINE +The current command line. +This variable is available only in shell functions and external +commands invoked by the +programmable completion facilities (@pxref{Programmable Completion}). + +@item COMP_POINT +The index of the current cursor position relative to the beginning of +the current command. +If the current cursor position is at the end of the current command, +the value of this variable is equal to @code{$@{#COMP_LINE@}}. +This variable is available only in shell functions and external +commands invoked by the +programmable completion facilities (@pxref{Programmable Completion}). + +@item COMP_TYPE +Set to an integer value corresponding to the type of completion attempted +that caused a completion function to be called: +@var{TAB}, for normal completion, +@samp{?}, for listing completions after successive tabs, +@samp{!}, for listing alternatives on partial word completion, +@samp{@@}, to list completions if the word is not unmodified, +or +@samp{%}, for menu completion. +This variable is available only in shell functions and external +commands invoked by the +programmable completion facilities (@pxref{Programmable Completion}). + +@item COMP_KEY +The key (or final key of a key sequence) used to invoke the current +completion function. + +@item COMP_WORDBREAKS +The set of characters that the Readline library treats as word +separators when performing word completion. +If @code{COMP_WORDBREAKS} is unset, it loses its special properties, +even if it is subsequently reset. + +@item COMP_WORDS +An array variable consisting of the individual +words in the current command line. +The words are split on shell metacharacters as the shell parser would +separate them. +This variable is available only in shell functions invoked by the +programmable completion facilities (@pxref{Programmable Completion}). + +@item COMPREPLY +An array variable from which Bash reads the possible completions +generated by a shell function invoked by the programmable completion +facility (@pxref{Programmable Completion}). + +@item DIRSTACK +An array variable containing the current contents of the directory stack. +Directories appear in the stack in the order they are displayed by the +@code{dirs} builtin. +Assigning to members of this array variable may be used to modify +directories already in the stack, but the @code{pushd} and @code{popd} +builtins must be used to add and remove directories. +Assignment to this variable will not change the current directory. +If @env{DIRSTACK} is unset, it loses its special properties, even if +it is subsequently reset. + +@item EMACS +If Bash finds this variable in the environment when the shell +starts with value @samp{t}, it assumes that the shell is running in an +emacs shell buffer and disables line editing. + +@item EUID +The numeric effective user id of the current user. This variable +is readonly. + +@item FCEDIT +The editor used as a default by the @option{-e} option to the @code{fc} +builtin command. + +@item FIGNORE +A colon-separated list of suffixes to ignore when performing +filename completion. +A file name whose suffix matches one of the entries in +@env{FIGNORE} +is excluded from the list of matched file names. A sample +value is @samp{.o:~} + +@item FUNCNAME +An array variable containing the names of all shell functions +currently in the execution call stack. +The element with index 0 is the name of any currently-executing +shell function. +The bottom-most element is @code{"main"}. +This variable exists only when a shell function is executing. +Assignments to @env{FUNCNAME} have no effect and return an error status. +If @env{FUNCNAME} is unset, it loses its special properties, even if +it is subsequently reset. + +@item GLOBIGNORE +A colon-separated list of patterns defining the set of filenames to +be ignored by filename expansion. +If a filename matched by a filename expansion pattern also matches one +of the patterns in @env{GLOBIGNORE}, it is removed from the list +of matches. + +@item GROUPS +An array variable containing the list of groups of which the current +user is a member. +Assignments to @env{GROUPS} have no effect and return an error status. +If @env{GROUPS} is unset, it loses its special properties, even if it is +subsequently reset. + +@item histchars +Up to three characters which control history expansion, quick +substitution, and tokenization (@pxref{History Interaction}). +The first character is the +@var{history expansion} character, that is, the character which signifies the +start of a history expansion, normally @samp{!}. The second character is the +character which signifies `quick substitution' when seen as the first +character on a line, normally @samp{^}. The optional third character is the +character which indicates that the remainder of the line is a comment when +found as the first character of a word, usually @samp{#}. The history +comment character causes history substitution to be skipped for the +remaining words on the line. It does not necessarily cause the shell +parser to treat the rest of the line as a comment. + +@item HISTCMD +The history number, or index in the history list, of the current +command. If @env{HISTCMD} is unset, it loses its special properties, +even if it is subsequently reset. + +@item HISTCONTROL +A colon-separated list of values controlling how commands are saved on +the history list. +If the list of values includes @samp{ignorespace}, lines which begin +with a space character are not saved in the history list. +A value of @samp{ignoredups} causes lines which match the previous +history entry to not be saved. +A value of @samp{ignoreboth} is shorthand for +@samp{ignorespace} and @samp{ignoredups}. +A value of @samp{erasedups} causes all previous lines matching the +current line to be removed from the history list before that line +is saved. +Any value not in the above list is ignored. +If @env{HISTCONTROL} is unset, or does not include a valid value, +all lines read by the shell parser are saved on the history list, +subject to the value of @env{HISTIGNORE}. +The second and subsequent lines of a multi-line compound command are +not tested, and are added to the history regardless of the value of +@env{HISTCONTROL}. + +@item HISTFILE +The name of the file to which the command history is saved. The +default value is @file{~/.bash_history}. + +@item HISTFILESIZE +The maximum number of lines contained in the history file. When this +variable is assigned a value, the history file is truncated, if +necessary, by removing the oldest entries, +to contain no more than that number of lines. +The history file is also truncated to this size after +writing it when an interactive shell exits. +The default value is 500. + +@item HISTIGNORE +A colon-separated list of patterns used to decide which command +lines should be saved on the history list. Each pattern is +anchored at the beginning of the line and must match the complete +line (no implicit @samp{*} is appended). Each pattern is tested +against the line after the checks specified by @env{HISTCONTROL} +are applied. In addition to the normal shell pattern matching +characters, @samp{&} matches the previous history line. @samp{&} +may be escaped using a backslash; the backslash is removed +before attempting a match. +The second and subsequent lines of a multi-line compound command are +not tested, and are added to the history regardless of the value of +@env{HISTIGNORE}. + +@env{HISTIGNORE} subsumes the function of @env{HISTCONTROL}. A +pattern of @samp{&} is identical to @code{ignoredups}, and a +pattern of @samp{[ ]*} is identical to @code{ignorespace}. +Combining these two patterns, separating them with a colon, +provides the functionality of @code{ignoreboth}. + +@item HISTSIZE +The maximum number of commands to remember on the history list. +The default value is 500. + +@item HISTTIMEFORMAT +If this variable is set and not null, its value is used as a format string +for @var{strftime} to print the time stamp associated with each history +entry displayed by the @code{history} builtin. +If this variable is set, time stamps are written to the history file so +they may be preserved across shell sessions. + +@item HOSTFILE +Contains the name of a file in the same format as @file{/etc/hosts} that +should be read when the shell needs to complete a hostname. +The list of possible hostname completions may be changed while the shell +is running; +the next time hostname completion is attempted after the +value is changed, Bash adds the contents of the new file to the +existing list. +If @env{HOSTFILE} is set, but has no value, Bash attempts to read +@file{/etc/hosts} to obtain the list of possible hostname completions. +When @env{HOSTFILE} is unset, the hostname list is cleared. + +@item HOSTNAME +The name of the current host. + +@item HOSTTYPE +A string describing the machine Bash is running on. + +@item IGNOREEOF +Controls the action of the shell on receipt of an @code{EOF} character +as the sole input. If set, the value denotes the number +of consecutive @code{EOF} characters that can be read as the +first character on an input line +before the shell will exit. If the variable exists but does not +have a numeric value (or has no value) then the default is 10. +If the variable does not exist, then @code{EOF} signifies the end of +input to the shell. This is only in effect for interactive shells. + +@item INPUTRC +The name of the Readline initialization file, overriding the default +of @file{~/.inputrc}. + +@item LANG +Used to determine the locale category for any category not specifically +selected with a variable starting with @code{LC_}. + +@item LC_ALL +This variable overrides the value of @env{LANG} and any other +@code{LC_} variable specifying a locale category. + +@item LC_COLLATE +This variable determines the collation order used when sorting the +results of filename expansion, and +determines the behavior of range expressions, equivalence classes, +and collating sequences within filename expansion and pattern matching +(@pxref{Filename Expansion}). + +@item LC_CTYPE +This variable determines the interpretation of characters and the +behavior of character classes within filename expansion and pattern +matching (@pxref{Filename Expansion}). + +@item LC_MESSAGES +This variable determines the locale used to translate double-quoted +strings preceded by a @samp{$} (@pxref{Locale Translation}). + +@item LC_NUMERIC +This variable determines the locale category used for number formatting. + +@item LINENO +The line number in the script or shell function currently executing. + +@item LINES +Used by the @code{select} builtin command to determine the column length +for printing selection lists. Automatically set upon receipt of a +@code{SIGWINCH}. + +@item MACHTYPE +A string that fully describes the system type on which Bash +is executing, in the standard @sc{gnu} @var{cpu-company-system} format. + +@item MAILCHECK +How often (in seconds) that the shell should check for mail in the +files specified in the @env{MAILPATH} or @env{MAIL} variables. +The default is 60 seconds. When it is time to check +for mail, the shell does so before displaying the primary prompt. +If this variable is unset, or set to a value that is not a number +greater than or equal to zero, the shell disables mail checking. + +@item OLDPWD +The previous working directory as set by the @code{cd} builtin. + +@item OPTERR +If set to the value 1, Bash displays error messages +generated by the @code{getopts} builtin command. + +@item OSTYPE +A string describing the operating system Bash is running on. + +@item PIPESTATUS +An array variable (@pxref{Arrays}) +containing a list of exit status values from the processes +in the most-recently-executed foreground pipeline (which may +contain only a single command). + +@item POSIXLY_CORRECT +If this variable is in the environment when @code{bash} starts, the shell +enters @sc{posix} mode (@pxref{Bash POSIX Mode}) before reading the +startup files, as if the @option{--posix} invocation option had been supplied. +If it is set while the shell is running, @code{bash} enables @sc{posix} mode, +as if the command +@example +@code{set -o posix} +@end example +@noindent +had been executed. + +@item PPID +The process @sc{id} of the shell's parent process. This variable +is readonly. + +@item PROMPT_COMMAND +If set, the value is interpreted as a command to execute +before the printing of each primary prompt (@env{$PS1}). + +@item PS3 +The value of this variable is used as the prompt for the +@code{select} command. If this variable is not set, the +@code{select} command prompts with @samp{#? } + +@item PS4 +The value is the prompt printed before the command line is echoed +when the @option{-x} option is set (@pxref{The Set Builtin}). +The first character of @env{PS4} is replicated multiple times, as +necessary, to indicate multiple levels of indirection. +The default is @samp{+ }. + +@item PWD +The current working directory as set by the @code{cd} builtin. + +@item RANDOM +Each time this parameter is referenced, a random integer +between 0 and 32767 is generated. Assigning a value to this +variable seeds the random number generator. + +@item REPLY +The default variable for the @code{read} builtin. + +@item SECONDS +This variable expands to the number of seconds since the +shell was started. Assignment to this variable resets +the count to the value assigned, and the expanded value +becomes the value assigned plus the number of seconds +since the assignment. + +@item SHELL +The full pathname to the shell is kept in this environment variable. +If it is not set when the shell starts, +Bash assigns to it the full pathname of the current user's login shell. + +@item SHELLOPTS +A colon-separated list of enabled shell options. Each word in +the list is a valid argument for the @option{-o} option to the +@code{set} builtin command (@pxref{The Set Builtin}). +The options appearing in @env{SHELLOPTS} are those reported +as @samp{on} by @samp{set -o}. +If this variable is in the environment when Bash +starts up, each shell option in the list will be enabled before +reading any startup files. This variable is readonly. + +@item SHLVL +Incremented by one each time a new instance of Bash is started. This is +intended to be a count of how deeply your Bash shells are nested. + +@item TIMEFORMAT +The value of this parameter is used as a format string specifying +how the timing information for pipelines prefixed with the @code{time} +reserved word should be displayed. +The @samp{%} character introduces an +escape sequence that is expanded to a time value or other +information. +The escape sequences and their meanings are as +follows; the braces denote optional portions. + +@table @code + +@item %% +A literal @samp{%}. + +@item %[@var{p}][l]R +The elapsed time in seconds. + +@item %[@var{p}][l]U +The number of CPU seconds spent in user mode. + +@item %[@var{p}][l]S +The number of CPU seconds spent in system mode. + +@item %P +The CPU percentage, computed as (%U + %S) / %R. +@end table + +The optional @var{p} is a digit specifying the precision, the number of +fractional digits after a decimal point. +A value of 0 causes no decimal point or fraction to be output. +At most three places after the decimal point may be specified; values +of @var{p} greater than 3 are changed to 3. +If @var{p} is not specified, the value 3 is used. + +The optional @code{l} specifies a longer format, including minutes, of +the form @var{MM}m@var{SS}.@var{FF}s. +The value of @var{p} determines whether or not the fraction is included. + +If this variable is not set, Bash acts as if it had the value +@example +@code{$'\nreal\t%3lR\nuser\t%3lU\nsys\t%3lS'} +@end example +If the value is null, no timing information is displayed. +A trailing newline is added when the format string is displayed. + +@item TMOUT +If set to a value greater than zero, @code{TMOUT} is treated as the +default timeout for the @code{read} builtin (@pxref{Bash Builtins}). +The @code{select} command (@pxref{Conditional Constructs}) terminates +if input does not arrive after @code{TMOUT} seconds when input is coming +from a terminal. + +In an interactive shell, the value is interpreted as +the number of seconds to wait for input after issuing the primary +prompt when the shell is interactive. +Bash terminates after that number of seconds if input does +not arrive. + +@item TMPDIR +If set, Bash uses its value as the name of a directory in which +Bash creates temporary files for the shell's use. + +@item UID +The numeric real user id of the current user. This variable is readonly. + +@end vtable + +@node Bash Features +@chapter Bash Features + +This section describes features unique to Bash. + +@menu +* Invoking Bash:: Command line options that you can give + to Bash. +* Bash Startup Files:: When and how Bash executes scripts. +* Interactive Shells:: What an interactive shell is. +* Bash Conditional Expressions:: Primitives used in composing expressions for + the @code{test} builtin. +* Shell Arithmetic:: Arithmetic on shell variables. +* Aliases:: Substituting one command for another. +* Arrays:: Array Variables. +* The Directory Stack:: History of visited directories. +* Printing a Prompt:: Controlling the PS1 string. +* The Restricted Shell:: A more controlled mode of shell execution. +* Bash POSIX Mode:: Making Bash behave more closely to what + the POSIX standard specifies. +@end menu + +@node Invoking Bash +@section Invoking Bash + +@example +bash [long-opt] [-ir] [-abefhkmnptuvxdBCDHP] [-o @var{option}] [-O @var{shopt_option}] [@var{argument} @dots{}] +bash [long-opt] [-abefhkmnptuvxdBCDHP] [-o @var{option}] [-O @var{shopt_option}] -c @var{string} [@var{argument} @dots{}] +bash [long-opt] -s [-abefhkmnptuvxdBCDHP] [-o @var{option}] [-O @var{shopt_option}] [@var{argument} @dots{}] +@end example + +In addition to the single-character shell command-line options +(@pxref{The Set Builtin}), there are several multi-character +options that you can use. These options must appear on the command +line before the single-character options to be recognized. + +@table @code +@item --debugger +Arrange for the debugger profile to be executed before the shell +starts. Turns on extended debugging mode (see @ref{The Shopt Builtin} +for a description of the @code{extdebug} option to the @code{shopt} +builtin) and shell function tracing +(see @ref{The Set Builtin} for a description of the @code{-o functrace} +option). + +@item --dump-po-strings +A list of all double-quoted strings preceded by @samp{$} +is printed on the standard output +in the @sc{gnu} @code{gettext} PO (portable object) file format. +Equivalent to @option{-D} except for the output format. + +@item --dump-strings +Equivalent to @option{-D}. + +@item --help +Display a usage message on standard output and exit successfully. + +@item --init-file @var{filename} +@itemx --rcfile @var{filename} +Execute commands from @var{filename} (instead of @file{~/.bashrc}) +in an interactive shell. + +@item --login +Equivalent to @option{-l}. + +@item --noediting +Do not use the @sc{gnu} Readline library (@pxref{Command Line Editing}) +to read command lines when the shell is interactive. + +@item --noprofile +Don't load the system-wide startup file @file{/etc/profile} +or any of the personal initialization files +@file{~/.bash_profile}, @file{~/.bash_login}, or @file{~/.profile} +when Bash is invoked as a login shell. + +@item --norc +Don't read the @file{~/.bashrc} initialization file in an +interactive shell. This is on by default if the shell is +invoked as @code{sh}. + +@item --posix +Change the behavior of Bash where the default operation differs +from the @sc{posix} standard to match the standard. This +is intended to make Bash behave as a strict superset of that +standard. @xref{Bash POSIX Mode}, for a description of the Bash +@sc{posix} mode. + +@item --restricted +Make the shell a restricted shell (@pxref{The Restricted Shell}). + +@item --verbose +Equivalent to @option{-v}. Print shell input lines as they're read. + +@item --version +Show version information for this instance of +Bash on the standard output and exit successfully. + +@end table + +There are several single-character options that may be supplied at +invocation which are not available with the @code{set} builtin. + +@table @code +@item -c @var{string} +Read and execute commands from @var{string} after processing the +options, then exit. Any remaining arguments are assigned to the +positional parameters, starting with @code{$0}. + +@item -i +Force the shell to run interactively. Interactive shells are +described in @ref{Interactive Shells}. + +@item -l +Make this shell act as if it had been directly invoked by login. +When the shell is interactive, this is equivalent to starting a +login shell with @samp{exec -l bash}. +When the shell is not interactive, the login shell startup files will +be executed. +@samp{exec bash -l} or @samp{exec bash --login} +will replace the current shell with a Bash login shell. +@xref{Bash Startup Files}, for a description of the special behavior +of a login shell. + +@item -r +Make the shell a restricted shell (@pxref{The Restricted Shell}). + +@item -s +If this option is present, or if no arguments remain after option +processing, then commands are read from the standard input. +This option allows the positional parameters to be set +when invoking an interactive shell. + +@item -D +A list of all double-quoted strings preceded by @samp{$} +is printed on the standard output. +These are the strings that +are subject to language translation when the current locale +is not @code{C} or @code{POSIX} (@pxref{Locale Translation}). +This implies the @option{-n} option; no commands will be executed. + +@item [-+]O [@var{shopt_option}] +@var{shopt_option} is one of the shell options accepted by the +@code{shopt} builtin (@pxref{The Shopt Builtin}). +If @var{shopt_option} is present, @option{-O} sets the value of that option; +@option{+O} unsets it. +If @var{shopt_option} is not supplied, the names and values of the shell +options accepted by @code{shopt} are printed on the standard output. +If the invocation option is @option{+O}, the output is displayed in a format +that may be reused as input. + +@item -- +A @code{--} signals the end of options and disables further option +processing. +Any arguments after the @code{--} are treated as filenames and arguments. + +@end table + +@cindex login shell +A @emph{login} shell is one whose first character of argument zero is +@samp{-}, or one invoked with the @option{--login} option. + +@cindex interactive shell +An @emph{interactive} shell is one started without non-option arguments, +unless @option{-s} is specified, +without specifying the @option{-c} option, and whose input and output are both +connected to terminals (as determined by @code{isatty(3)}), or one +started with the @option{-i} option. @xref{Interactive Shells}, for more +information. + +If arguments remain after option processing, and neither the +@option{-c} nor the @option{-s} +option has been supplied, the first argument is assumed to +be the name of a file containing shell commands (@pxref{Shell Scripts}). +When Bash is invoked in this fashion, @code{$0} +is set to the name of the file, and the positional parameters +are set to the remaining arguments. +Bash reads and executes commands from this file, then exits. +Bash's exit status is the exit status of the last command executed +in the script. If no commands are executed, the exit status is 0. + +@node Bash Startup Files +@section Bash Startup Files +@cindex startup files + +This section describes how Bash executes its startup files. +If any of the files exist but cannot be read, Bash reports an error. +Tildes are expanded in file names as described above under +Tilde Expansion (@pxref{Tilde Expansion}). + +Interactive shells are described in @ref{Interactive Shells}. + +@subsubheading Invoked as an interactive login shell, or with @option{--login} + +When Bash is invoked as an interactive login shell, or as a +non-interactive shell with the @option{--login} option, it first reads and +executes commands from the file @file{/etc/profile}, if that file exists. +After reading that file, it looks for @file{~/.bash_profile}, +@file{~/.bash_login}, and @file{~/.profile}, in that order, and reads +and executes commands from the first one that exists and is readable. +The @option{--noprofile} option may be used when the shell is started to +inhibit this behavior. + +When a login shell exits, Bash reads and executes commands from +the file @file{~/.bash_logout}, if it exists. + +@subsubheading Invoked as an interactive non-login shell + +When an interactive shell that is not a login shell is started, Bash +reads and executes commands from @file{~/.bashrc}, if that file exists. +This may be inhibited by using the @option{--norc} option. +The @option{--rcfile @var{file}} option will force Bash to read and +execute commands from @var{file} instead of @file{~/.bashrc}. + +So, typically, your @file{~/.bash_profile} contains the line +@example +@code{if [ -f ~/.bashrc ]; then . ~/.bashrc; fi} +@end example +@noindent +after (or before) any login-specific initializations. + +@subsubheading Invoked non-interactively + +When Bash is started non-interactively, to run a shell script, +for example, it looks for the variable @env{BASH_ENV} in the environment, +expands its value if it appears there, and uses the expanded value as +the name of a file to read and execute. Bash behaves as if the +following command were executed: +@example +@code{if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi} +@end example +@noindent +but the value of the @env{PATH} variable is not used to search for the +file name. + +As noted above, if a non-interactive shell is invoked with the +@option{--login} option, Bash attempts to read and execute commands from the +login shell startup files. + +@subsubheading Invoked with name @code{sh} + +If Bash is invoked with the name @code{sh}, it tries to mimic the +startup behavior of historical versions of @code{sh} as closely as +possible, while conforming to the @sc{posix} standard as well. + +When invoked as an interactive login shell, or as a non-interactive +shell with the @option{--login} option, it first attempts to read +and execute commands from @file{/etc/profile} and @file{~/.profile}, in +that order. +The @option{--noprofile} option may be used to inhibit this behavior. +When invoked as an interactive shell with the name @code{sh}, Bash +looks for the variable @env{ENV}, expands its value if it is defined, +and uses the expanded value as the name of a file to read and execute. +Since a shell invoked as @code{sh} does not attempt to read and execute +commands from any other startup files, the @option{--rcfile} option has +no effect. +A non-interactive shell invoked with the name @code{sh} does not attempt +to read any other startup files. + +When invoked as @code{sh}, Bash enters @sc{posix} mode after +the startup files are read. + +@subsubheading Invoked in @sc{posix} mode + +When Bash is started in @sc{posix} mode, as with the +@option{--posix} command line option, it follows the @sc{posix} standard +for startup files. +In this mode, interactive shells expand the @env{ENV} variable +and commands are read and executed from the file whose name is the +expanded value. +No other startup files are read. + +@subsubheading Invoked by remote shell daemon + +Bash attempts to determine when it is being run by the remote shell +daemon, usually @code{rshd}. If Bash determines it is being run by +rshd, it reads and executes commands from @file{~/.bashrc}, if that +file exists and is readable. +It will not do this if invoked as @code{sh}. +The @option{--norc} option may be used to inhibit this behavior, and the +@option{--rcfile} option may be used to force another file to be read, but +@code{rshd} does not generally invoke the shell with those options or +allow them to be specified. + +@subsubheading Invoked with unequal effective and real @sc{uid/gid}s + +If Bash is started with the effective user (group) id not equal to the +real user (group) id, and the @code{-p} option is not supplied, no startup +files are read, shell functions are not inherited from the environment, +the @env{SHELLOPTS} variable, if it appears in the environment, is ignored, +and the effective user id is set to the real user id. +If the @code{-p} option is supplied at invocation, the startup behavior is +the same, but the effective user id is not reset. + +@node Interactive Shells +@section Interactive Shells +@cindex interactive shell +@cindex shell, interactive + +@menu +* What is an Interactive Shell?:: What determines whether a shell is Interactive. +* Is this Shell Interactive?:: How to tell if a shell is interactive. +* Interactive Shell Behavior:: What changes in a interactive shell? +@end menu + +@node What is an Interactive Shell? +@subsection What is an Interactive Shell? + +An interactive shell +is one started without non-option arguments, unless @option{-s} is +specified, without specifying the @option{-c} option, and +whose input and error output are both +connected to terminals (as determined by @code{isatty(3)}), +or one started with the @option{-i} option. + +An interactive shell generally reads from and writes to a user's +terminal. + +The @option{-s} invocation option may be used to set the positional parameters +when an interactive shell is started. + +@node Is this Shell Interactive? +@subsection Is this Shell Interactive? + +To determine within a startup script whether or not Bash is +running interactively, +test the value of the @samp{-} special parameter. +It contains @code{i} when the shell is interactive. For example: + +@example +case "$-" in +*i*) echo This shell is interactive ;; +*) echo This shell is not interactive ;; +esac +@end example + +Alternatively, startup scripts may examine the variable +@env{PS1}; it is unset in non-interactive shells, and set in +interactive shells. Thus: + +@example +if [ -z "$PS1" ]; then + echo This shell is not interactive +else + echo This shell is interactive +fi +@end example + +@node Interactive Shell Behavior +@subsection Interactive Shell Behavior + +When the shell is running interactively, it changes its behavior in +several ways. + +@enumerate +@item +Startup files are read and executed as described in @ref{Bash Startup Files}. + +@item +Job Control (@pxref{Job Control}) is enabled by default. When job +control is in effect, Bash ignores the keyboard-generated job control +signals @code{SIGTTIN}, @code{SIGTTOU}, and @code{SIGTSTP}. + +@item +Bash expands and displays @env{PS1} before reading the first line +of a command, and expands and displays @env{PS2} before reading the +second and subsequent lines of a multi-line command. + +@item +Bash executes the value of the @env{PROMPT_COMMAND} variable as a command +before printing the primary prompt, @env{$PS1} +(@pxref{Bash Variables}). + +@item +Readline (@pxref{Command Line Editing}) is used to read commands from +the user's terminal. + +@item +Bash inspects the value of the @code{ignoreeof} option to @code{set -o} +instead of exiting immediately when it receives an @code{EOF} on its +standard input when reading a command (@pxref{The Set Builtin}). + +@item +Command history (@pxref{Bash History Facilities}) +and history expansion (@pxref{History Interaction}) +are enabled by default. +Bash will save the command history to the file named by @env{$HISTFILE} +when an interactive shell exits. + +@item +Alias expansion (@pxref{Aliases}) is performed by default. + +@item +In the absence of any traps, Bash ignores @code{SIGTERM} +(@pxref{Signals}). + +@item +In the absence of any traps, @code{SIGINT} is caught and handled +((@pxref{Signals}). +@code{SIGINT} will interrupt some shell builtins. + +@item +An interactive login shell sends a @code{SIGHUP} to all jobs on exit +if the @code{huponexit} shell option has been enabled (@pxref{Signals}). + +@item +The @option{-n} invocation option is ignored, and @samp{set -n} has +no effect (@pxref{The Set Builtin}). + +@item +Bash will check for mail periodically, depending on the values of the +@env{MAIL}, @env{MAILPATH}, and @env{MAILCHECK} shell variables +(@pxref{Bash Variables}). + +@item +Expansion errors due to references to unbound shell variables after +@samp{set -u} has been enabled will not cause the shell to exit +(@pxref{The Set Builtin}). + +@item +The shell will not exit on expansion errors caused by @var{var} being unset +or null in @code{$@{@var{var}:?@var{word}@}} expansions +(@pxref{Shell Parameter Expansion}). + +@item +Redirection errors encountered by shell builtins will not cause the +shell to exit. + +@item +When running in @sc{posix} mode, a special builtin returning an error +status will not cause the shell to exit (@pxref{Bash POSIX Mode}). + +@item +A failed @code{exec} will not cause the shell to exit +(@pxref{Bourne Shell Builtins}). + +@item +Parser syntax errors will not cause the shell to exit. + +@item +Simple spelling correction for directory arguments to the @code{cd} +builtin is enabled by default (see the description of the @code{cdspell} +option to the @code{shopt} builtin in @ref{The Shopt Builtin}). + +@item +The shell will check the value of the @env{TMOUT} variable and exit +if a command is not read within the specified number of seconds after +printing @env{$PS1} (@pxref{Bash Variables}). + +@end enumerate + +@node Bash Conditional Expressions +@section Bash Conditional Expressions +@cindex expressions, conditional + +Conditional expressions are used by the @code{[[} compound command +and the @code{test} and @code{[} builtin commands. + +Expressions may be unary or binary. +Unary expressions are often used to examine the status of a file. +There are string operators and numeric comparison operators as well. +If the @var{file} argument to one of the primaries is of the form +@file{/dev/fd/@var{N}}, then file descriptor @var{N} is checked. +If the @var{file} argument to one of the primaries is one of +@file{/dev/stdin}, @file{/dev/stdout}, or @file{/dev/stderr}, file +descriptor 0, 1, or 2, respectively, is checked. + +Unless otherwise specified, primaries that operate on files follow symbolic +links and operate on the target of the link, rather than the link itself. + +@table @code +@item -a @var{file} +True if @var{file} exists. + +@item -b @var{file} +True if @var{file} exists and is a block special file. + +@item -c @var{file} +True if @var{file} exists and is a character special file. + +@item -d @var{file} +True if @var{file} exists and is a directory. + +@item -e @var{file} +True if @var{file} exists. + +@item -f @var{file} +True if @var{file} exists and is a regular file. + +@item -g @var{file} +True if @var{file} exists and its set-group-id bit is set. + +@item -h @var{file} +True if @var{file} exists and is a symbolic link. + +@item -k @var{file} +True if @var{file} exists and its "sticky" bit is set. + +@item -p @var{file} +True if @var{file} exists and is a named pipe (FIFO). + +@item -r @var{file} +True if @var{file} exists and is readable. + +@item -s @var{file} +True if @var{file} exists and has a size greater than zero. + +@item -t @var{fd} +True if file descriptor @var{fd} is open and refers to a terminal. + +@item -u @var{file} +True if @var{file} exists and its set-user-id bit is set. + +@item -w @var{file} +True if @var{file} exists and is writable. + +@item -x @var{file} +True if @var{file} exists and is executable. + +@item -O @var{file} +True if @var{file} exists and is owned by the effective user id. + +@item -G @var{file} +True if @var{file} exists and is owned by the effective group id. + +@item -L @var{file} +True if @var{file} exists and is a symbolic link. + +@item -S @var{file} +True if @var{file} exists and is a socket. + +@item -N @var{file} +True if @var{file} exists and has been modified since it was last read. + +@item @var{file1} -nt @var{file2} +True if @var{file1} is newer (according to modification date) +than @var{file2}, or if @var{file1} exists and @var{file2} does not. + +@item @var{file1} -ot @var{file2} +True if @var{file1} is older than @var{file2}, +or if @var{file2} exists and @var{file1} does not. + +@item @var{file1} -ef @var{file2} +True if @var{file1} and @var{file2} refer to the same device and +inode numbers. + +@item -o @var{optname} +True if shell option @var{optname} is enabled. +The list of options appears in the description of the @option{-o} +option to the @code{set} builtin (@pxref{The Set Builtin}). + +@item -z @var{string} +True if the length of @var{string} is zero. + +@item -n @var{string} +@itemx @var{string} +True if the length of @var{string} is non-zero. + +@item @var{string1} == @var{string2} +True if the strings are equal. +@samp{=} may be used in place of @samp{==} for strict @sc{posix} compliance. + +@item @var{string1} != @var{string2} +True if the strings are not equal. + +@item @var{string1} < @var{string2} +True if @var{string1} sorts before @var{string2} lexicographically +in the current locale. + +@item @var{string1} > @var{string2} +True if @var{string1} sorts after @var{string2} lexicographically +in the current locale. + +@item @var{arg1} OP @var{arg2} +@code{OP} is one of +@samp{-eq}, @samp{-ne}, @samp{-lt}, @samp{-le}, @samp{-gt}, or @samp{-ge}. +These arithmetic binary operators return true if @var{arg1} +is equal to, not equal to, less than, less than or equal to, +greater than, or greater than or equal to @var{arg2}, +respectively. @var{Arg1} and @var{arg2} +may be positive or negative integers. + +@end table + +@node Shell Arithmetic +@section Shell Arithmetic +@cindex arithmetic, shell +@cindex shell arithmetic +@cindex expressions, arithmetic +@cindex evaluation, arithmetic +@cindex arithmetic evaluation + +The shell allows arithmetic expressions to be evaluated, as one of +the shell expansions or by the @code{let} and the @option{-i} option +to the @code{declare} builtins. + +Evaluation is done in fixed-width integers with no check for overflow, +though division by 0 is trapped and flagged as an error. +The operators and their precedence, associativity, and values +are the same as in the C language. +The following list of operators is grouped into levels of +equal-precedence operators. +The levels are listed in order of decreasing precedence. + +@table @code + +@item @var{id}++ @var{id}-- +variable post-increment and post-decrement + +@item ++@var{id} --@var{id} +variable pre-increment and pre-decrement + +@item - + +unary minus and plus + +@item ! ~ +logical and bitwise negation + +@item ** +exponentiation + +@item * / % +multiplication, division, remainder + +@item + - +addition, subtraction + +@item << >> +left and right bitwise shifts + +@item <= >= < > +comparison + +@item == != +equality and inequality + +@item & +bitwise AND + +@item ^ +bitwise exclusive OR + +@item | +bitwise OR + +@item && +logical AND + +@item || +logical OR + +@item expr ? expr : expr +conditional operator + +@item = *= /= %= += -= <<= >>= &= ^= |= +assignment + +@item expr1 , expr2 +comma +@end table + +Shell variables are allowed as operands; parameter expansion is +performed before the expression is evaluated. +Within an expression, shell variables may also be referenced by name +without using the parameter expansion syntax. +A shell variable that is null or unset evaluates to 0 when referenced +by name without using the parameter expansion syntax. +The value of a variable is evaluated as an arithmetic expression +when it is referenced, or when a variable which has been given the +@var{integer} attribute using @samp{declare -i} is assigned a value. +A null value evaluates to 0. +A shell variable need not have its integer attribute turned on +to be used in an expression. + +Constants with a leading 0 are interpreted as octal numbers. +A leading @samp{0x} or @samp{0X} denotes hexadecimal. Otherwise, +numbers take the form [@var{base}@code{#}]@var{n}, where @var{base} +is a decimal number between 2 and 64 representing the arithmetic +base, and @var{n} is a number in that base. If @var{base}@code{#} is +omitted, then base 10 is used. +The digits greater than 9 are represented by the lowercase letters, +the uppercase letters, @samp{@@}, and @samp{_}, in that order. +If @var{base} is less than or equal to 36, lowercase and uppercase +letters may be used interchangeably to represent numbers between 10 +and 35. + +Operators are evaluated in order of precedence. Sub-expressions in +parentheses are evaluated first and may override the precedence +rules above. + +@node Aliases +@section Aliases +@cindex alias expansion + +@var{Aliases} allow a string to be substituted for a word when it is used +as the first word of a simple command. +The shell maintains a list of aliases that may be set and unset with +the @code{alias} and @code{unalias} builtin commands. + +The first word of each simple command, if unquoted, is checked to see +if it has an alias. +If so, that word is replaced by the text of the alias. +The characters @samp{/}, @samp{$}, @samp{`}, @samp{=} and any of the +shell metacharacters or quoting characters listed above may not appear +in an alias name. +The replacement text may contain any valid +shell input, including shell metacharacters. +The first word of the replacement text is tested for +aliases, but a word that is identical to an alias being expanded +is not expanded a second time. +This means that one may alias @code{ls} to @code{"ls -F"}, +for instance, and Bash does not try to recursively expand the +replacement text. If the last character of the alias value is a +space or tab character, then the next command word following the +alias is also checked for alias expansion. + +Aliases are created and listed with the @code{alias} +command, and removed with the @code{unalias} command. + +There is no mechanism for using arguments in the replacement text, +as in @code{csh}. +If arguments are needed, a shell function should be used +(@pxref{Shell Functions}). + +Aliases are not expanded when the shell is not interactive, +unless the @code{expand_aliases} shell option is set using +@code{shopt} (@pxref{The Shopt Builtin}). + +The rules concerning the definition and use of aliases are +somewhat confusing. Bash +always reads at least one complete line +of input before executing any +of the commands on that line. Aliases are expanded when a +command is read, not when it is executed. Therefore, an +alias definition appearing on the same line as another +command does not take effect until the next line of input is read. +The commands following the alias definition +on that line are not affected by the new alias. +This behavior is also an issue when functions are executed. +Aliases are expanded when a function definition is read, +not when the function is executed, because a function definition +is itself a compound command. As a consequence, aliases +defined in a function are not available until after that +function is executed. To be safe, always put +alias definitions on a separate line, and do not use @code{alias} +in compound commands. + +For almost every purpose, shell functions are preferred over aliases. + +@node Arrays +@section Arrays +@cindex arrays + +Bash provides one-dimensional array variables. Any variable may be used as +an array; the @code{declare} builtin will explicitly declare an array. +There is no maximum +limit on the size of an array, nor any requirement that members +be indexed or assigned contiguously. Arrays are zero-based. + +An array is created automatically if any variable is assigned to using +the syntax +@example +name[@var{subscript}]=@var{value} +@end example + +@noindent +The @var{subscript} +is treated as an arithmetic expression that must evaluate to a number +greater than or equal to zero. To explicitly declare an array, use +@example +declare -a @var{name} +@end example +@noindent +The syntax +@example +declare -a @var{name}[@var{subscript}] +@end example +@noindent +is also accepted; the @var{subscript} is ignored. Attributes may be +specified for an array variable using the @code{declare} and +@code{readonly} builtins. Each attribute applies to all members of +an array. + +Arrays are assigned to using compound assignments of the form +@example +name=(value@var{1} @dots{} value@var{n}) +@end example +@noindent +where each +@var{value} is of the form @code{[[@var{subscript}]=]}@var{string}. If +the optional subscript is supplied, that index is assigned to; +otherwise the index of the element assigned is the last index assigned +to by the statement plus one. Indexing starts at zero. +This syntax is also accepted by the @code{declare} +builtin. Individual array elements may be assigned to using the +@code{name[}@var{subscript}@code{]=}@var{value} syntax introduced above. + +Any element of an array may be referenced using +@code{$@{name[}@var{subscript}@code{]@}}. +The braces are required to avoid +conflicts with the shell's filename expansion operators. If the +@var{subscript} is @samp{@@} or @samp{*}, the word expands to all members +of the array @var{name}. These subscripts differ only when the word +appears within double quotes. +If the word is double-quoted, +@code{$@{name[*]@}} expands to a single word with +the value of each array member separated by the first character of the +@env{IFS} variable, and @code{$@{name[@@]@}} expands each element of +@var{name} to a separate word. When there are no array members, +@code{$@{name[@@]@}} expands to nothing. +If the double-quoted expansion occurs within a word, the expansion of +the first parameter is joined with the beginning part of the original +word, and the expansion of the last parameter is joined with the last +part of the original word. +This is analogous to the +expansion of the special parameters @samp{@@} and @samp{*}. +@code{$@{#name[}@var{subscript}@code{]@}} expands to the length of +@code{$@{name[}@var{subscript}@code{]@}}. +If @var{subscript} is @samp{@@} or +@samp{*}, the expansion is the number of elements in the array. +Referencing an array variable without a subscript is equivalent to +referencing element zero. + +The @code{unset} builtin is used to destroy arrays. +@code{unset} @var{name}[@var{subscript}] +destroys the array element at index @var{subscript}. +Care must be taken to avoid unwanted side effects caused by filename +generation. +@code{unset} @var{name}, where @var{name} is an array, removes the +entire array. A subscript of @samp{*} or @samp{@@} also removes the +entire array. + +The @code{declare}, @code{local}, and @code{readonly} +builtins each accept a @option{-a} +option to specify an array. The @code{read} +builtin accepts a @option{-a} +option to assign a list of words read from the standard input +to an array, and can read values from the standard input into +individual array elements. The @code{set} and @code{declare} +builtins display array values in a way that allows them to be +reused as input. + +@node The Directory Stack +@section The Directory Stack +@cindex directory stack + +@menu +* Directory Stack Builtins:: Bash builtin commands to manipulate + the directory stack. +@end menu + +The directory stack is a list of recently-visited directories. The +@code{pushd} builtin adds directories to the stack as it changes +the current directory, and the @code{popd} builtin removes specified +directories from the stack and changes the current directory to +the directory removed. The @code{dirs} builtin displays the contents +of the directory stack. + +The contents of the directory stack are also visible +as the value of the @env{DIRSTACK} shell variable. + +@node Directory Stack Builtins +@subsection Directory Stack Builtins + +@table @code + +@item dirs +@btindex dirs +@example +dirs [+@var{N} | -@var{N}] [-clpv] +@end example +Display the list of currently remembered directories. Directories +are added to the list with the @code{pushd} command; the +@code{popd} command removes directories from the list. +@table @code +@item +@var{N} +Displays the @var{N}th directory (counting from the left of the +list printed by @code{dirs} when invoked without options), starting +with zero. +@item -@var{N} +Displays the @var{N}th directory (counting from the right of the +list printed by @code{dirs} when invoked without options), starting +with zero. +@item -c +Clears the directory stack by deleting all of the elements. +@item -l +Produces a longer listing; the default listing format uses a +tilde to denote the home directory. +@item -p +Causes @code{dirs} to print the directory stack with one entry per +line. +@item -v +Causes @code{dirs} to print the directory stack with one entry per +line, prefixing each entry with its index in the stack. +@end table + +@item popd +@btindex popd +@example +popd [+@var{N} | -@var{N}] [-n] +@end example + +Remove the top entry from the directory stack, and @code{cd} +to the new top directory. +When no arguments are given, @code{popd} +removes the top directory from the stack and +performs a @code{cd} to the new top directory. The +elements are numbered from 0 starting at the first directory listed with +@code{dirs}; i.e., @code{popd} is equivalent to @code{popd +0}. +@table @code +@item +@var{N} +Removes the @var{N}th directory (counting from the left of the +list printed by @code{dirs}), starting with zero. +@item -@var{N} +Removes the @var{N}th directory (counting from the right of the +list printed by @code{dirs}), starting with zero. +@item -n +Suppresses the normal change of directory when removing directories +from the stack, so that only the stack is manipulated. +@end table + +@btindex pushd +@item pushd +@example +pushd [-n] [@var{+N} | @var{-N} | @var{dir} ] +@end example + +Save the current directory on the top of the directory stack +and then @code{cd} to @var{dir}. +With no arguments, @code{pushd} exchanges the top two directories. + +@table @code +@item -n +Suppresses the normal change of directory when adding directories +to the stack, so that only the stack is manipulated. +@item +@var{N} +Brings the @var{N}th directory (counting from the left of the +list printed by @code{dirs}, starting with zero) to the top of +the list by rotating the stack. +@item -@var{N} +Brings the @var{N}th directory (counting from the right of the +list printed by @code{dirs}, starting with zero) to the top of +the list by rotating the stack. +@item @var{dir} +Makes the current working directory be the top of the stack, and then +executes the equivalent of `@code{cd} @var{dir}'. +@code{cd}s to @var{dir}. +@end table + +@end table + +@node Printing a Prompt +@section Controlling the Prompt +@cindex prompting + +The value of the variable @env{PROMPT_COMMAND} is examined just before +Bash prints each primary prompt. If @env{PROMPT_COMMAND} is set and +has a non-null value, then the +value is executed just as if it had been typed on the command line. + +In addition, the following table describes the special characters which +can appear in the prompt variables: + +@table @code +@item \a +A bell character. +@item \d +The date, in "Weekday Month Date" format (e.g., "Tue May 26"). +@item \D@{@var{format}@} +The @var{format} is passed to @code{strftime}(3) and the result is inserted +into the prompt string; an empty @var{format} results in a locale-specific +time representation. The braces are required. +@item \e +An escape character. +@item \h +The hostname, up to the first `.'. +@item \H +The hostname. +@item \j +The number of jobs currently managed by the shell. +@item \l +The basename of the shell's terminal device name. +@item \n +A newline. +@item \r +A carriage return. +@item \s +The name of the shell, the basename of @code{$0} (the portion +following the final slash). +@item \t +The time, in 24-hour HH:MM:SS format. +@item \T +The time, in 12-hour HH:MM:SS format. +@item \@@ +The time, in 12-hour am/pm format. +@item \A +The time, in 24-hour HH:MM format. +@item \u +The username of the current user. +@item \v +The version of Bash (e.g., 2.00) +@item \V +The release of Bash, version + patchlevel (e.g., 2.00.0) +@item \w +The current working directory, with @env{$HOME} abbreviated with a tilde. +@item \W +The basename of @env{$PWD}, with @env{$HOME} abbreviated with a tilde. +@item \! +The history number of this command. +@item \# +The command number of this command. +@item \$ +If the effective uid is 0, @code{#}, otherwise @code{$}. +@item \@var{nnn} +The character whose ASCII code is the octal value @var{nnn}. +@item \\ +A backslash. +@item \[ +Begin a sequence of non-printing characters. This could be used to +embed a terminal control sequence into the prompt. +@item \] +End a sequence of non-printing characters. +@end table + +The command number and the history number are usually different: +the history number of a command is its position in the history +list, which may include commands restored from the history file +(@pxref{Bash History Facilities}), while the command number is +the position in the sequence of commands executed during the current +shell session. + +After the string is decoded, it is expanded via +parameter expansion, command substitution, arithmetic +expansion, and quote removal, subject to the value of the +@code{promptvars} shell option (@pxref{Bash Builtins}). + +@node The Restricted Shell +@section The Restricted Shell +@cindex restricted shell + +If Bash is started with the name @code{rbash}, or the +@option{--restricted} +or +@option{-r} +option is supplied at invocation, the shell becomes restricted. +A restricted shell is used to +set up an environment more controlled than the standard shell. +A restricted shell behaves identically to @code{bash} +with the exception that the following are disallowed or not performed: + +@itemize @bullet +@item +Changing directories with the @code{cd} builtin. +@item +Setting or unsetting the values of the @env{SHELL}, @env{PATH}, +@env{ENV}, or @env{BASH_ENV} variables. +@item +Specifying command names containing slashes. +@item +Specifying a filename containing a slash as an argument to the @code{.} +builtin command. +@item +Specifying a filename containing a slash as an argument to the @option{-p} +option to the @code{hash} builtin command. +@item +Importing function definitions from the shell environment at startup. +@item +Parsing the value of @env{SHELLOPTS} from the shell environment at startup. +@item +Redirecting output using the @samp{>}, @samp{>|}, @samp{<>}, @samp{>&}, +@samp{&>}, and @samp{>>} redirection operators. +@item +Using the @code{exec} builtin to replace the shell with another command. +@item +Adding or deleting builtin commands with the +@option{-f} and @option{-d} options to the @code{enable} builtin. +@item +Using the @code{enable} builtin command to enable disabled shell builtins. +@item +Specifying the @option{-p} option to the @code{command} builtin. +@item +Turning off restricted mode with @samp{set +r} or @samp{set +o restricted}. +@end itemize + +These restrictions are enforced after any startup files are read. + +When a command that is found to be a shell script is executed +(@pxref{Shell Scripts}), @code{rbash} turns off any restrictions in +the shell spawned to execute the script. + +@node Bash POSIX Mode +@section Bash POSIX Mode +@cindex POSIX Mode + +Starting Bash with the @option{--posix} command-line option or executing +@samp{set -o posix} while Bash is running will cause Bash to conform more +closely to the @sc{posix} standard by changing the behavior to +match that specified by @sc{posix} in areas where the Bash default differs. + +When invoked as @code{sh}, Bash enters @sc{posix} mode after reading the +startup files. + +The following list is what's changed when `@sc{posix} mode' is in effect: + +@enumerate +@item +When a command in the hash table no longer exists, Bash will re-search +@env{$PATH} to find the new location. This is also available with +@samp{shopt -s checkhash}. + +@item +The message printed by the job control code and builtins when a job +exits with a non-zero status is `Done(status)'. + +@item +The message printed by the job control code and builtins when a job +is stopped is `Stopped(@var{signame})', where @var{signame} is, for +example, @code{SIGTSTP}. + +@item +The @code{bg} builtin uses the required format to describe each job placed +in the background, which does not include an indication of whether the job +is the current or previous job. + +@item +Reserved words appearing in a context where reserved words are recognized +do not undergo alias expansion. + +@item +The @sc{posix} @env{PS1} and @env{PS2} expansions of @samp{!} to +the history number and @samp{!!} to @samp{!} are enabled, +and parameter expansion is performed on the values of @env{PS1} and +@env{PS2} regardless of the setting of the @code{promptvars} option. + +@item +The @sc{posix} startup files are executed (@env{$ENV}) rather than +the normal Bash files. + +@item +Tilde expansion is only performed on assignments preceding a command +name, rather than on all assignment statements on the line. + +@item +The default history file is @file{~/.sh_history} (this is the +default value of @env{$HISTFILE}). + +@item +The output of @samp{kill -l} prints all the signal names on a single line, +separated by spaces, without the @samp{SIG} prefix. + +@item +The @code{kill} builtin does not accept signal names with a @samp{SIG} +prefix. + +@item +Non-interactive shells exit if @var{filename} in @code{.} @var{filename} +is not found. + +@item +Non-interactive shells exit if a syntax error in an arithmetic expansion +results in an invalid expression. + +@item +Redirection operators do not perform filename expansion on the word +in the redirection unless the shell is interactive. + +@item +Redirection operators do not perform word splitting on the word in the +redirection. + +@item +Function names must be valid shell @code{name}s. That is, they may not +contain characters other than letters, digits, and underscores, and +may not start with a digit. Declaring a function with an invalid name +causes a fatal syntax error in non-interactive shells. + +@item +@sc{posix} special builtins are found before shell functions +during command lookup. + +@item +If a @sc{posix} special builtin returns an error status, a +non-interactive shell exits. The fatal errors are those listed in +the POSIX standard, and include things like passing incorrect options, +redirection errors, variable assignment errors for assignments preceding +the command name, and so on. + +@item +If @env{CDPATH} is set, the @code{cd} builtin will not implicitly +append the current directory to it. This means that @code{cd} will +fail if no valid directory name can be constructed from +any of the entries in @env{$CDPATH}, even if the a directory with +the same name as the name given as an argument to @code{cd} exists +in the current directory. + +@item +A non-interactive shell exits with an error status if a variable +assignment error occurs when no command name follows the assignment +statements. +A variable assignment error occurs, for example, when trying to assign +a value to a readonly variable. + +@item +A non-interactive shell exits with an error status if the iteration +variable in a @code{for} statement or the selection variable in a +@code{select} statement is a readonly variable. + +@item +Process substitution is not available. + +@item +Assignment statements preceding @sc{posix} special builtins +persist in the shell environment after the builtin completes. + +@item +Assignment statements preceding shell function calls persist in the +shell environment after the function returns, as if a @sc{posix} +special builtin command had been executed. + +@item +The @code{export} and @code{readonly} builtin commands display their +output in the format required by @sc{posix}. + +@item +The @code{trap} builtin displays signal names without the leading +@code{SIG}. + +@item +The @code{trap} builtin doesn't check the first argument for a possible +signal specification and revert the signal handling to the original +disposition if it is, unless that argument consists solely of digits and +is a valid signal number. If users want to reset the handler for a given +signal to the original disposition, they should use @samp{-} as the +first argument. + +@item +The @code{.} and @code{source} builtins do not search the current directory +for the filename argument if it is not found by searching @env{PATH}. + +@item +Subshells spawned to execute command substitutions inherit the value of +the @option{-e} option from the parent shell. When not in @sc{posix} mode, +Bash clears the @option{-e} option in such subshells. + +@item +Alias expansion is always enabled, even in non-interactive shells. + +@item +When the @code{alias} builtin displays alias definitions, it does not +display them with a leading @samp{alias } unless the @option{-p} option +is supplied. + +@item +When the @code{set} builtin is invoked without options, it does not display +shell function names and definitions. + +@item +When the @code{set} builtin is invoked without options, it displays +variable values without quotes, unless they contain shell metacharacters, +even if the result contains nonprinting characters. + +@item +When the @code{cd} builtin is invoked in @var{logical} mode, and the pathname +constructed from @code{$PWD} and the directory name supplied as an argument +does not refer to an existing directory, @code{cd} will fail instead of +falling back to @var{physical} mode. + +@item +When the @code{pwd} builtin is supplied the @option{-P} option, it resets +@code{$PWD} to a pathname containing no symlinks. + +@item +The @code{pwd} builtin verifies that the value it prints is the same as the +current directory, even if it is not asked to check the file system with the +@option{-P} option. + +@item +When listing the history, the @code{fc} builtin does not include an +indication of whether or not a history entry has been modified. + +@item +The default editor used by @code{fc} is @code{ed}. + +@item +The @code{type} and @code{command} builtins will not report a non-executable +file as having been found, though the shell will attempt to execute such a +file if it is the only so-named file found in @code{$PATH}. + +@item +The @code{vi} editing mode will invoke the @code{vi} editor directly when +the @samp{v} command is run, instead of checking @code{$FCEDIT} and +@code{$EDITOR}. + +@item +When the @code{xpg_echo} option is enabled, Bash does not attempt to interpret +any arguments to @code{echo} as options. Each argument is displayed, after +escape characters are converted. + +@end enumerate + +There is other @sc{posix} behavior that Bash does not implement by +default even when in @sc{posix} mode. +Specifically: + +@enumerate + +@item +The @code{fc} builtin checks @code{$EDITOR} as a program to edit history +entries if @code{FCEDIT} is unset, rather than defaulting directly to +@code{ed}. @code{fc} uses @code{ed} if @code{EDITOR} is unset. + +@item +As noted above, Bash requires the @code{xpg_echo} option to be enabled for +the @code{echo} builtin to be fully conformant. + +@end enumerate + +Bash can be configured to be @sc{posix}-conformant by default, by specifying +the @option{--enable-strict-posix-default} to @code{configure} when building +(@pxref{Optional Features}). + +@node Job Control +@chapter Job Control + +This chapter discusses what job control is, how it works, and how +Bash allows you to access its facilities. + +@menu +* Job Control Basics:: How job control works. +* Job Control Builtins:: Bash builtin commands used to interact + with job control. +* Job Control Variables:: Variables Bash uses to customize job + control. +@end menu + +@node Job Control Basics +@section Job Control Basics +@cindex job control +@cindex foreground +@cindex background +@cindex suspending jobs + +Job control +refers to the ability to selectively stop (suspend) +the execution of processes and continue (resume) +their execution at a later point. A user typically employs +this facility via an interactive interface supplied jointly +by the system's terminal driver and Bash. + +The shell associates a @var{job} with each pipeline. It keeps a +table of currently executing jobs, which may be listed with the +@code{jobs} command. When Bash starts a job +asynchronously, it prints a line that looks +like: +@example +[1] 25647 +@end example +@noindent +indicating that this job is job number 1 and that the process @sc{id} +of the last process in the pipeline associated with this job is +25647. All of the processes in a single pipeline are members of +the same job. Bash uses the @var{job} abstraction as the +basis for job control. + +To facilitate the implementation of the user interface to job +control, the operating system maintains the notion of a current terminal +process group @sc{id}. Members of this process group (processes whose +process group @sc{id} is equal to the current terminal process group +@sc{id}) receive keyboard-generated signals such as @code{SIGINT}. +These processes are said to be in the foreground. Background +processes are those whose process group @sc{id} differs from the +terminal's; such processes are immune to keyboard-generated +signals. Only foreground processes are allowed to read from or +write to the terminal. Background processes which attempt to +read from (write to) the terminal are sent a @code{SIGTTIN} +(@code{SIGTTOU}) signal by the terminal driver, which, unless +caught, suspends the process. + +If the operating system on which Bash is running supports +job control, Bash contains facilities to use it. Typing the +@var{suspend} character (typically @samp{^Z}, Control-Z) while a +process is running causes that process to be stopped and returns +control to Bash. Typing the @var{delayed suspend} character +(typically @samp{^Y}, Control-Y) causes the process to be stopped +when it attempts to read input from the terminal, and control to +be returned to Bash. The user then manipulates the state of +this job, using the @code{bg} command to continue it in the +background, the @code{fg} command to continue it in the +foreground, or the @code{kill} command to kill it. A @samp{^Z} +takes effect immediately, and has the additional side effect of +causing pending output and typeahead to be discarded. + +There are a number of ways to refer to a job in the shell. The +character @samp{%} introduces a job name. + +Job number @code{n} may be referred to as @samp{%n}. +The symbols @samp{%%} and @samp{%+} refer to the shell's notion of the +current job, which is the last job stopped while it was in the foreground +or started in the background. +A single @samp{%} (with no accompanying job specification) also refers +to the current job. +The previous job may be referenced using @samp{%-}. In output +pertaining to jobs (e.g., the output of the @code{jobs} command), +the current job is always flagged with a @samp{+}, and the +previous job with a @samp{-}. + +A job may also be referred to +using a prefix of the name used to start it, or using a substring +that appears in its command line. For example, @samp{%ce} refers +to a stopped @code{ce} job. Using @samp{%?ce}, on the +other hand, refers to any job containing the string @samp{ce} in +its command line. If the prefix or substring matches more than one job, +Bash reports an error. + +Simply naming a job can be used to bring it into the foreground: +@samp{%1} is a synonym for @samp{fg %1}, bringing job 1 from the +background into the foreground. Similarly, @samp{%1 &} resumes +job 1 in the background, equivalent to @samp{bg %1} + +The shell learns immediately whenever a job changes state. +Normally, Bash waits until it is about to print a prompt +before reporting changes in a job's status so as to not interrupt +any other output. +If the @option{-b} option to the @code{set} builtin is enabled, +Bash reports such changes immediately (@pxref{The Set Builtin}). +Any trap on @code{SIGCHLD} is executed for each child process +that exits. + +If an attempt to exit Bash is made while jobs are stopped, (or running, if +the @code{checkjobs} option is enabled -- see @ref{The Shopt Builtin}), the +shell prints a warning message, and if the @code{checkjobs} option is +enabled, lists the jobs and their statuses. +The @code{jobs} command may then be used to inspect their status. +If a second attempt to exit is made without an intervening command, +Bash does not print another warning, and any stopped jobs are terminated. + +@node Job Control Builtins +@section Job Control Builtins + +@table @code + +@item bg +@btindex bg +@example +bg [@var{jobspec} @dots{}] +@end example +Resume each suspended job @var{jobspec} in the background, as if it +had been started with @samp{&}. +If @var{jobspec} is not supplied, the current job is used. +The return status is zero unless it is run when job control is not +enabled, or, when run with job control enabled, any +@var{jobspec} was not found or specifies a job +that was started without job control. + +@item fg +@btindex fg +@example +fg [@var{jobspec}] +@end example +Resume the job @var{jobspec} in the foreground and make it the current job. +If @var{jobspec} is not supplied, the current job is used. +The return status is that of the command placed into the foreground, +or non-zero if run when job control is disabled or, when run with +job control enabled, @var{jobspec} does not specify a valid job or +@var{jobspec} specifies a job that was started without job control. + +@item jobs +@btindex jobs +@example +jobs [-lnprs] [@var{jobspec}] +jobs -x @var{command} [@var{arguments}] +@end example + +The first form lists the active jobs. The options have the +following meanings: + +@table @code +@item -l +List process @sc{id}s in addition to the normal information. + +@item -n +Display information only about jobs that have changed status since +the user was last notified of their status. + +@item -p +List only the process @sc{id} of the job's process group leader. + +@item -r +Restrict output to running jobs. + +@item -s +Restrict output to stopped jobs. +@end table + +If @var{jobspec} is given, +output is restricted to information about that job. +If @var{jobspec} is not supplied, the status of all jobs is +listed. + +If the @option{-x} option is supplied, @code{jobs} replaces any +@var{jobspec} found in @var{command} or @var{arguments} with the +corresponding process group @sc{id}, and executes @var{command}, +passing it @var{argument}s, returning its exit status. + +@item kill +@btindex kill +@example +kill [-s @var{sigspec}] [-n @var{signum}] [-@var{sigspec}] @var{jobspec} or @var{pid} +kill -l [@var{exit_status}] +@end example +Send a signal specified by @var{sigspec} or @var{signum} to the process +named by job specification @var{jobspec} or process @sc{id} @var{pid}. +@var{sigspec} is either a case-insensitive signal name such as +@code{SIGINT} (with or without the @code{SIG} prefix) +or a signal number; @var{signum} is a signal number. +If @var{sigspec} and @var{signum} are not present, @code{SIGTERM} is used. +The @option{-l} option lists the signal names. +If any arguments are supplied when @option{-l} is given, the names of the +signals corresponding to the arguments are listed, and the return status +is zero. +@var{exit_status} is a number specifying a signal number or the exit +status of a process terminated by a signal. +The return status is zero if at least one signal was successfully sent, +or non-zero if an error occurs or an invalid option is encountered. + +@item wait +@btindex wait +@example +wait [@var{jobspec} or @var{pid} ...] +@end example +Wait until the child process specified by each process @sc{id} @var{pid} +or job specification @var{jobspec} exits and return the exit status of the +last command waited for. +If a job spec is given, all processes in the job are waited for. +If no arguments are given, all currently active child processes are +waited for, and the return status is zero. +If neither @var{jobspec} nor @var{pid} specifies an active child process +of the shell, the return status is 127. + +@item disown +@btindex disown +@example +disown [-ar] [-h] [@var{jobspec} @dots{}] +@end example +Without options, each @var{jobspec} is removed from the table of +active jobs. +If the @option{-h} option is given, the job is not removed from the table, +but is marked so that @code{SIGHUP} is not sent to the job if the shell +receives a @code{SIGHUP}. +If @var{jobspec} is not present, and neither the @option{-a} nor @option{-r} +option is supplied, the current job is used. +If no @var{jobspec} is supplied, the @option{-a} option means to remove or +mark all jobs; the @option{-r} option without a @var{jobspec} +argument restricts operation to running jobs. + +@item suspend +@btindex suspend +@example +suspend [-f] +@end example +Suspend the execution of this shell until it receives a +@code{SIGCONT} signal. The @option{-f} option means to suspend +even if the shell is a login shell. + +@end table + +When job control is not active, the @code{kill} and @code{wait} +builtins do not accept @var{jobspec} arguments. They must be +supplied process @sc{id}s. + +@node Job Control Variables +@section Job Control Variables + +@vtable @code + +@item auto_resume +This variable controls how the shell interacts with the user and +job control. If this variable exists then single word simple +commands without redirections are treated as candidates for resumption +of an existing job. There is no ambiguity allowed; if there is +more than one job beginning with the string typed, then +the most recently accessed job will be selected. +The name of a stopped job, in this context, is the command line +used to start it. If this variable is set to the value @samp{exact}, +the string supplied must match the name of a stopped job exactly; +if set to @samp{substring}, +the string supplied needs to match a substring of the name of a +stopped job. The @samp{substring} value provides functionality +analogous to the @samp{%?} job @sc{id} (@pxref{Job Control Basics}). +If set to any other value, the supplied string must +be a prefix of a stopped job's name; this provides functionality +analogous to the @samp{%} job @sc{id}. + +@end vtable + +@set readline-appendix +@set history-appendix +@cindex Readline, how to use +@include rluser.texi +@cindex History, how to use +@include hsuser.texi +@clear readline-appendix +@clear history-appendix + +@node Installing Bash +@chapter Installing Bash + +This chapter provides basic instructions for installing Bash on +the various supported platforms. The distribution supports the +@sc{gnu} operating systems, nearly every version of Unix, and several +non-Unix systems such as BeOS and Interix. +Other independent ports exist for +@sc{ms-dos}, @sc{os/2}, and Windows platforms. + +@menu +* Basic Installation:: Installation instructions. +* Compilers and Options:: How to set special options for various + systems. +* Compiling For Multiple Architectures:: How to compile Bash for more + than one kind of system from + the same source tree. +* Installation Names:: How to set the various paths used by the installation. +* Specifying the System Type:: How to configure Bash for a particular system. +* Sharing Defaults:: How to share default configuration values among GNU + programs. +* Operation Controls:: Options recognized by the configuration program. +* Optional Features:: How to enable and disable optional features when + building Bash. +@end menu + +@node Basic Installation +@section Basic Installation +@cindex installation +@cindex configuration +@cindex Bash installation +@cindex Bash configuration + +These are installation instructions for Bash. + +The simplest way to compile Bash is: + +@enumerate +@item +@code{cd} to the directory containing the source code and type +@samp{./configure} to configure Bash for your system. If you're +using @code{csh} on an old version of System V, you might need to +type @samp{sh ./configure} instead to prevent @code{csh} from trying +to execute @code{configure} itself. + +Running @code{configure} takes some time. +While running, it prints messages telling which features it is +checking for. + +@item +Type @samp{make} to compile Bash and build the @code{bashbug} bug +reporting script. + +@item +Optionally, type @samp{make tests} to run the Bash test suite. + +@item +Type @samp{make install} to install @code{bash} and @code{bashbug}. +This will also install the manual pages and Info file. + +@end enumerate + +The @code{configure} shell script attempts to guess correct +values for various system-dependent variables used during +compilation. It uses those values to create a @file{Makefile} in +each directory of the package (the top directory, the +@file{builtins}, @file{doc}, and @file{support} directories, +each directory under @file{lib}, and several others). It also creates a +@file{config.h} file containing system-dependent definitions. +Finally, it creates a shell script named @code{config.status} that you +can run in the future to recreate the current configuration, a +file @file{config.cache} that saves the results of its tests to +speed up reconfiguring, and a file @file{config.log} containing +compiler output (useful mainly for debugging @code{configure}). +If at some point +@file{config.cache} contains results you don't want to keep, you +may remove or edit it. + +To find out more about the options and arguments that the +@code{configure} script understands, type + +@example +bash-2.04$ ./configure --help +@end example + +@noindent +at the Bash prompt in your Bash source directory. + +If you need to do unusual things to compile Bash, please +try to figure out how @code{configure} could check whether or not +to do them, and mail diffs or instructions to +@email{bash-maintainers@@gnu.org} so they can be +considered for the next release. + +The file @file{configure.in} is used to create @code{configure} +by a program called Autoconf. You only need +@file{configure.in} if you want to change it or regenerate +@code{configure} using a newer version of Autoconf. If +you do this, make sure you are using Autoconf version 2.50 or +newer. + +You can remove the program binaries and object files from the +source code directory by typing @samp{make clean}. To also remove the +files that @code{configure} created (so you can compile Bash for +a different kind of computer), type @samp{make distclean}. + +@node Compilers and Options +@section Compilers and Options + +Some systems require unusual options for compilation or linking +that the @code{configure} script does not know about. You can +give @code{configure} initial values for variables by setting +them in the environment. Using a Bourne-compatible shell, you +can do that on the command line like this: + +@example +CC=c89 CFLAGS=-O2 LIBS=-lposix ./configure +@end example + +On systems that have the @code{env} program, you can do it like this: + +@example +env CPPFLAGS=-I/usr/local/include LDFLAGS=-s ./configure +@end example + +The configuration process uses GCC to build Bash if it +is available. + +@node Compiling For Multiple Architectures +@section Compiling For Multiple Architectures + +You can compile Bash for more than one kind of computer at the +same time, by placing the object files for each architecture in their +own directory. To do this, you must use a version of @code{make} that +supports the @code{VPATH} variable, such as GNU @code{make}. +@code{cd} to the +directory where you want the object files and executables to go and run +the @code{configure} script from the source directory. You may need to +supply the @option{--srcdir=PATH} argument to tell @code{configure} where the +source files are. @code{configure} automatically checks for the +source code in the directory that @code{configure} is in and in `..'. + +If you have to use a @code{make} that does not supports the @code{VPATH} +variable, you can compile Bash for one architecture at a +time in the source code directory. After you have installed +Bash for one architecture, use @samp{make distclean} before +reconfiguring for another architecture. + +Alternatively, if your system supports symbolic links, you can use the +@file{support/mkclone} script to create a build tree which has +symbolic links back to each file in the source directory. Here's an +example that creates a build directory in the current directory from a +source directory @file{/usr/gnu/src/bash-2.0}: + +@example +bash /usr/gnu/src/bash-2.0/support/mkclone -s /usr/gnu/src/bash-2.0 . +@end example + +@noindent +The @code{mkclone} script requires Bash, so you must have already built +Bash for at least one architecture before you can create build +directories for other architectures. + +@node Installation Names +@section Installation Names + +By default, @samp{make install} will install into +@file{/usr/local/bin}, @file{/usr/local/man}, etc. You can +specify an installation prefix other than @file{/usr/local} by +giving @code{configure} the option @option{--prefix=@var{PATH}}, +or by specifying a value for the @code{DESTDIR} @samp{make} +variable when running @samp{make install}. + +You can specify separate installation prefixes for +architecture-specific files and architecture-independent files. +If you give @code{configure} the option +@option{--exec-prefix=@var{PATH}}, @samp{make install} will use +@var{PATH} as the prefix for installing programs and libraries. +Documentation and other data files will still use the regular prefix. + +@node Specifying the System Type +@section Specifying the System Type + +There may be some features @code{configure} can not figure out +automatically, but need to determine by the type of host Bash +will run on. Usually @code{configure} can figure that +out, but if it prints a message saying it can not guess the host +type, give it the @option{--host=TYPE} option. @samp{TYPE} can +either be a short name for the system type, such as @samp{sun4}, +or a canonical name with three fields: @samp{CPU-COMPANY-SYSTEM} +(e.g., @samp{i386-unknown-freebsd4.2}). + +See the file @file{support/config.sub} for the possible +values of each field. + +@node Sharing Defaults +@section Sharing Defaults + +If you want to set default values for @code{configure} scripts to +share, you can create a site shell script called +@code{config.site} that gives default values for variables like +@code{CC}, @code{cache_file}, and @code{prefix}. @code{configure} +looks for @file{PREFIX/share/config.site} if it exists, then +@file{PREFIX/etc/config.site} if it exists. Or, you can set the +@code{CONFIG_SITE} environment variable to the location of the site +script. A warning: the Bash @code{configure} looks for a site script, +but not all @code{configure} scripts do. + +@node Operation Controls +@section Operation Controls + +@code{configure} recognizes the following options to control how it +operates. + +@table @code + +@item --cache-file=@var{file} +Use and save the results of the tests in +@var{file} instead of @file{./config.cache}. Set @var{file} to +@file{/dev/null} to disable caching, for debugging +@code{configure}. + +@item --help +Print a summary of the options to @code{configure}, and exit. + +@item --quiet +@itemx --silent +@itemx -q +Do not print messages saying which checks are being made. + +@item --srcdir=@var{dir} +Look for the Bash source code in directory @var{dir}. Usually +@code{configure} can determine that directory automatically. + +@item --version +Print the version of Autoconf used to generate the @code{configure} +script, and exit. +@end table + +@code{configure} also accepts some other, not widely used, boilerplate +options. @samp{configure --help} prints the complete list. + +@node Optional Features +@section Optional Features + +The Bash @code{configure} has a number of @option{--enable-@var{feature}} +options, where @var{feature} indicates an optional part of Bash. +There are also several @option{--with-@var{package}} options, +where @var{package} is something like @samp{bash-malloc} or @samp{purify}. +To turn off the default use of a package, use +@option{--without-@var{package}}. To configure Bash without a feature +that is enabled by default, use @option{--disable-@var{feature}}. + +Here is a complete list of the @option{--enable-} and +@option{--with-} options that the Bash @code{configure} recognizes. + +@table @code +@item --with-afs +Define if you are using the Andrew File System from Transarc. + +@item --with-bash-malloc +Use the Bash version of +@code{malloc} in the directory @file{lib/malloc}. This is not the same +@code{malloc} that appears in @sc{gnu} libc, but an older version +originally derived from the 4.2 @sc{bsd} @code{malloc}. This @code{malloc} +is very fast, but wastes some space on each allocation. +This option is enabled by default. +The @file{NOTES} file contains a list of systems for +which this should be turned off, and @code{configure} disables this +option automatically for a number of systems. + +@item --with-curses +Use the curses library instead of the termcap library. This should +be supplied if your system has an inadequate or incomplete termcap +database. + +@item --with-gnu-malloc +A synonym for @code{--with-bash-malloc}. + +@item --with-installed-readline[=@var{PREFIX}] +Define this to make Bash link with a locally-installed version of Readline +rather than the version in @file{lib/readline}. This works only with +Readline 5.0 and later versions. If @var{PREFIX} is @code{yes} or not +supplied, @code{configure} uses the values of the make variables +@code{includedir} and @code{libdir}, which are subdirectories of @code{prefix} +by default, to find the installed version of Readline if it is not in +the standard system include and library directories. +If @var{PREFIX} is @code{no}, Bash links with the version in +@file{lib/readline}. +If @var{PREFIX} is set to any other value, @code{configure} treats it as +a directory pathname and looks for +the installed version of Readline in subdirectories of that directory +(include files in @var{PREFIX}/@code{include} and the library in +@var{PREFIX}/@code{lib}). + +@item --with-purify +Define this to use the Purify memory allocation checker from Rational +Software. + +@item --enable-minimal-config +This produces a shell with minimal features, close to the historical +Bourne shell. +@end table + +There are several @option{--enable-} options that alter how Bash is +compiled and linked, rather than changing run-time features. + +@table @code +@item --enable-largefile +Enable support for @uref{http://www.sas.com/standards/large_file/x_open.20Mar96.html, +large files} if the operating system requires special compiler options +to build programs which can access large files. This is enabled by +default, if the operating system provides large file support. + +@item --enable-profiling +This builds a Bash binary that produces profiling information to be +processed by @code{gprof} each time it is executed. + +@item --enable-static-link +This causes Bash to be linked statically, if @code{gcc} is being used. +This could be used to build a version to use as root's shell. +@end table + +The @samp{minimal-config} option can be used to disable all of +the following options, but it is processed first, so individual +options may be enabled using @samp{enable-@var{feature}}. + +All of the following options except for @samp{disabled-builtins} and +@samp{xpg-echo-default} are +enabled by default, unless the operating system does not provide the +necessary support. + +@table @code +@item --enable-alias +Allow alias expansion and include the @code{alias} and @code{unalias} +builtins (@pxref{Aliases}). + +@item --enable-arith-for-command +Include support for the alternate form of the @code{for} command +that behaves like the C language @code{for} statement +(@pxref{Looping Constructs}). + +@item --enable-array-variables +Include support for one-dimensional array shell variables +(@pxref{Arrays}). + +@item --enable-bang-history +Include support for @code{csh}-like history substitution +(@pxref{History Interaction}). + +@item --enable-brace-expansion +Include @code{csh}-like brace expansion +( @code{b@{a,b@}c} @expansion{} @code{bac bbc} ). +See @ref{Brace Expansion}, for a complete description. + +@item --enable-command-timing +Include support for recognizing @code{time} as a reserved word and for +displaying timing statistics for the pipeline following @code{time} +(@pxref{Pipelines}). +This allows pipelines as well as shell builtins and functions to be timed. + +@item --enable-cond-command +Include support for the @code{[[} conditional command. +(@pxref{Conditional Constructs}). + +@item --enable-cond-regexp +Include support for matching POSIX regular expressions using the +@samp{=~} binary operator in the @code{[[} conditional command. +(@pxref{Conditional Constructs}). + +@item --enable-debugger +Include support for the bash debugger (distributed separately). + +@item --enable-directory-stack +Include support for a @code{csh}-like directory stack and the +@code{pushd}, @code{popd}, and @code{dirs} builtins +(@pxref{The Directory Stack}). + +@item --enable-disabled-builtins +Allow builtin commands to be invoked via @samp{builtin xxx} +even after @code{xxx} has been disabled using @samp{enable -n xxx}. +See @ref{Bash Builtins}, for details of the @code{builtin} and +@code{enable} builtin commands. + +@item --enable-dparen-arithmetic +Include support for the @code{((@dots{}))} command +(@pxref{Conditional Constructs}). + +@item --enable-extended-glob +Include support for the extended pattern matching features described +above under @ref{Pattern Matching}. + +@item --enable-help-builtin +Include the @code{help} builtin, which displays help on shell builtins and +variables (@pxref{Bash Builtins}). + +@item --enable-history +Include command history and the @code{fc} and @code{history} +builtin commands (@pxref{Bash History Facilities}). + +@item --enable-job-control +This enables the job control features (@pxref{Job Control}), +if the operating system supports them. + +@item --enable-multibyte +This enables support for multibyte characters if the operating +system provides the necessary support. + +@item --enable-net-redirections +This enables the special handling of filenames of the form +@code{/dev/tcp/@var{host}/@var{port}} and +@code{/dev/udp/@var{host}/@var{port}} +when used in redirections (@pxref{Redirections}). + +@item --enable-process-substitution +This enables process substitution (@pxref{Process Substitution}) if +the operating system provides the necessary support. + +@item --enable-progcomp +Enable the programmable completion facilities +(@pxref{Programmable Completion}). +If Readline is not enabled, this option has no effect. + +@item --enable-prompt-string-decoding +Turn on the interpretation of a number of backslash-escaped characters +in the @env{$PS1}, @env{$PS2}, @env{$PS3}, and @env{$PS4} prompt +strings. See @ref{Printing a Prompt}, for a complete list of prompt +string escape sequences. + +@item --enable-readline +Include support for command-line editing and history with the Bash +version of the Readline library (@pxref{Command Line Editing}). + +@item --enable-restricted +Include support for a @dfn{restricted shell}. If this is enabled, Bash, +when called as @code{rbash}, enters a restricted mode. See +@ref{The Restricted Shell}, for a description of restricted mode. + +@item --enable-select +Include the @code{select} builtin, which allows the generation of simple +menus (@pxref{Conditional Constructs}). + +@item --enable-separate-helpfiles +Use external files for the documentation displayed by the @code{help} builtin +instead of storing the text internally. + +@item --enable-single-help-strings +Store the text displayed by the @code{help} builtin as a single string for +each help topic. This aids in translating the text to different languages. +You may need to disable this if your compiler cannot handle very long string +literals. + +@item --enable-strict-posix-default +Make Bash @sc{posix}-conformant by default (@pxref{Bash POSIX Mode}). + +@item --enable-usg-echo-default +A synonym for @code{--enable-xpg-echo-default}. + +@item --enable-xpg-echo-default +Make the @code{echo} builtin expand backslash-escaped characters by default, +without requiring the @option{-e} option. +This sets the default value of the @code{xpg_echo} shell option to @code{on}, +which makes the Bash @code{echo} behave more like the version specified in +the Single Unix Specification, version 3. +@xref{Bash Builtins}, for a description of the escape sequences that +@code{echo} recognizes. + +@end table + +The file @file{config-top.h} contains C Preprocessor +@samp{#define} statements for options which are not settable from +@code{configure}. +Some of these are not meant to be changed; beware of the consequences if +you do. +Read the comments associated with each definition for more +information about its effect. + +@node Reporting Bugs +@appendix Reporting Bugs + +Please report all bugs you find in Bash. +But first, you should +make sure that it really is a bug, and that it appears in the latest +version of Bash. +The latest version of Bash is always available for FTP from +@uref{ftp://ftp.gnu.org/pub/bash/}. + +Once you have determined that a bug actually exists, use the +@code{bashbug} command to submit a bug report. +If you have a fix, you are encouraged to mail that as well! +Suggestions and `philosophical' bug reports may be mailed +to @email{bug-bash@@gnu.org} or posted to the Usenet +newsgroup @code{gnu.bash.bug}. + +All bug reports should include: +@itemize @bullet +@item +The version number of Bash. +@item +The hardware and operating system. +@item +The compiler used to compile Bash. +@item +A description of the bug behaviour. +@item +A short script or `recipe' which exercises the bug and may be used +to reproduce it. +@end itemize + +@noindent +@code{bashbug} inserts the first three items automatically into +the template it provides for filing a bug report. + +Please send all reports concerning this manual to +@email{chet@@po.CWRU.Edu}. + +@node Major Differences From The Bourne Shell +@appendix Major Differences From The Bourne Shell + +Bash implements essentially the same grammar, parameter and +variable expansion, redirection, and quoting as the Bourne Shell. +Bash uses the @sc{posix} standard as the specification of +how these features are to be implemented. There are some +differences between the traditional Bourne shell and Bash; this +section quickly details the differences of significance. A +number of these differences are explained in greater depth in +previous sections. +This section uses the version of @code{sh} included in SVR4.2 (the +last version of the historical Bourne shell) as the baseline reference. + +@itemize @bullet + +@item +Bash is @sc{posix}-conformant, even where the @sc{posix} specification +differs from traditional @code{sh} behavior (@pxref{Bash POSIX Mode}). + +@item +Bash has multi-character invocation options (@pxref{Invoking Bash}). + +@item +Bash has command-line editing (@pxref{Command Line Editing}) and +the @code{bind} builtin. + +@item +Bash provides a programmable word completion mechanism +(@pxref{Programmable Completion}), and two builtin commands, +@code{complete} and @code{compgen}, to manipulate it. + +@item +Bash has command history (@pxref{Bash History Facilities}) and the +@code{history} and @code{fc} builtins to manipulate it. +The Bash history list maintains timestamp information and uses the +value of the @code{HISTTIMEFORMAT} variable to display it. + +@item +Bash implements @code{csh}-like history expansion +(@pxref{History Interaction}). + +@item +Bash has one-dimensional array variables (@pxref{Arrays}), and the +appropriate variable expansions and assignment syntax to use them. +Several of the Bash builtins take options to act on arrays. +Bash provides a number of built-in array variables. + +@item +The @code{$'@dots{}'} quoting syntax, which expands ANSI-C +backslash-escaped characters in the text between the single quotes, +is supported (@pxref{ANSI-C Quoting}). + +@item +Bash supports the @code{$"@dots{}"} quoting syntax to do +locale-specific translation of the characters between the double +quotes. The @option{-D}, @option{--dump-strings}, and @option{--dump-po-strings} +invocation options list the translatable strings found in a script +(@pxref{Locale Translation}). + +@item +Bash implements the @code{!} keyword to negate the return value of +a pipeline (@pxref{Pipelines}). +Very useful when an @code{if} statement needs to act only if a test fails. +The Bash @samp{-o pipefail} option to @code{set} will cause a pipeline to +return a failure status if any command fails. + +@item +Bash has the @code{time} reserved word and command timing (@pxref{Pipelines}). +The display of the timing statistics may be controlled with the +@env{TIMEFORMAT} variable. + +@item +Bash implements the @code{for (( @var{expr1} ; @var{expr2} ; @var{expr3} ))} +arithmetic for command, similar to the C language (@pxref{Looping Constructs}). + +@item +Bash includes the @code{select} compound command, which allows the +generation of simple menus (@pxref{Conditional Constructs}). + +@item +Bash includes the @code{[[} compound command, which makes conditional +testing part of the shell grammar (@pxref{Conditional Constructs}), including +optional regular expression matching. + +@item +Bash provides optional case-insensitive matching for the @code{case} and +@code{[[} constructs. + +@item +Bash includes brace expansion (@pxref{Brace Expansion}) and tilde +expansion (@pxref{Tilde Expansion}). + +@item +Bash implements command aliases and the @code{alias} and @code{unalias} +builtins (@pxref{Aliases}). + +@item +Bash provides shell arithmetic, the @code{((} compound command +(@pxref{Conditional Constructs}), +and arithmetic expansion (@pxref{Shell Arithmetic}). + +@item +Variables present in the shell's initial environment are automatically +exported to child processes. The Bourne shell does not normally do +this unless the variables are explicitly marked using the @code{export} +command. + +@item +Bash supports the @samp{+=} assignment operator, which appends to the value +of the variable named on the left hand side. + +@item +Bash includes the @sc{posix} pattern removal @samp{%}, @samp{#}, @samp{%%} +and @samp{##} expansions to remove leading or trailing substrings from +variable values (@pxref{Shell Parameter Expansion}). + +@item +The expansion @code{$@{#xx@}}, which returns the length of @code{$@{xx@}}, +is supported (@pxref{Shell Parameter Expansion}). + +@item +The expansion @code{$@{var:}@var{offset}@code{[:}@var{length}@code{]@}}, +which expands to the substring of @code{var}'s value of length +@var{length}, beginning at @var{offset}, is present +(@pxref{Shell Parameter Expansion}). + +@item +The expansion +@code{$@{var/[/]}@var{pattern}@code{[/}@var{replacement}@code{]@}}, +which matches @var{pattern} and replaces it with @var{replacement} in +the value of @code{var}, is available (@pxref{Shell Parameter Expansion}). + +@item +The expansion @code{$@{!@var{prefix@}*}} expansion, which expands to +the names of all shell variables whose names begin with @var{prefix}, +is available (@pxref{Shell Parameter Expansion}). + +@item +Bash has @var{indirect} variable expansion using @code{$@{!word@}} +(@pxref{Shell Parameter Expansion}). + +@item +Bash can expand positional parameters beyond @code{$9} using +@code{$@{@var{num}@}}. + +@item +The @sc{posix} @code{$()} form of command substitution +is implemented (@pxref{Command Substitution}), +and preferred to the Bourne shell's @code{``} (which +is also implemented for backwards compatibility). + +@item +Bash has process substitution (@pxref{Process Substitution}). + +@item +Bash automatically assigns variables that provide information about the +current user (@env{UID}, @env{EUID}, and @env{GROUPS}), the current host +(@env{HOSTTYPE}, @env{OSTYPE}, @env{MACHTYPE}, and @env{HOSTNAME}), +and the instance of Bash that is running (@env{BASH}, +@env{BASH_VERSION}, and @env{BASH_VERSINFO}). @xref{Bash Variables}, +for details. + +@item +The @env{IFS} variable is used to split only the results of expansion, +not all words (@pxref{Word Splitting}). +This closes a longstanding shell security hole. + +@item +Bash implements the full set of @sc{posix} filename expansion operators, +including @var{character classes}, @var{equivalence classes}, and +@var{collating symbols} (@pxref{Filename Expansion}). + +@item +Bash implements extended pattern matching features when the @code{extglob} +shell option is enabled (@pxref{Pattern Matching}). + +@item +It is possible to have a variable and a function with the same name; +@code{sh} does not separate the two name spaces. + +@item +Bash functions are permitted to have local variables using the +@code{local} builtin, and thus useful recursive functions may be written +(@pxref{Bash Builtins}). + +@item +Variable assignments preceding commands affect only that command, even +builtins and functions (@pxref{Environment}). +In @code{sh}, all variable assignments +preceding commands are global unless the command is executed from the +file system. + +@item +Bash performs filename expansion on filenames specified as operands +to input and output redirection operators (@pxref{Redirections}). + +@item +Bash contains the @samp{<>} redirection operator, allowing a file to be +opened for both reading and writing, and the @samp{&>} redirection +operator, for directing standard output and standard error to the same +file (@pxref{Redirections}). + +@item +Bash includes the @samp{<<<} redirection operator, allowing a string to +be used as the standard input to a command. + +@item +Bash implements the @samp{[n]<&@var{word}} and @samp{[n]>&@var{word}} +redirection operators, which move one file descriptor to another. + +@item +Bash treats a number of filenames specially when they are +used in redirection operators (@pxref{Redirections}). + +@item +Bash can open network connections to arbitrary machines and services +with the redirection operators (@pxref{Redirections}). + +@item +The @code{noclobber} option is available to avoid overwriting existing +files with output redirection (@pxref{The Set Builtin}). +The @samp{>|} redirection operator may be used to override @code{noclobber}. + +@item +The Bash @code{cd} and @code{pwd} builtins (@pxref{Bourne Shell Builtins}) +each take @option{-L} and @option{-P} options to switch between logical and +physical modes. + +@item +Bash allows a function to override a builtin with the same name, and provides +access to that builtin's functionality within the function via the +@code{builtin} and @code{command} builtins (@pxref{Bash Builtins}). + +@item +The @code{command} builtin allows selective disabling of functions +when command lookup is performed (@pxref{Bash Builtins}). + +@item +Individual builtins may be enabled or disabled using the @code{enable} +builtin (@pxref{Bash Builtins}). + +@item +The Bash @code{exec} builtin takes additional options that allow users +to control the contents of the environment passed to the executed +command, and what the zeroth argument to the command is to be +(@pxref{Bourne Shell Builtins}). + +@item +Shell functions may be exported to children via the environment +using @code{export -f} (@pxref{Shell Functions}). + +@item +The Bash @code{export}, @code{readonly}, and @code{declare} builtins can +take a @option{-f} option to act on shell functions, a @option{-p} option to +display variables with various attributes set in a format that can be +used as shell input, a @option{-n} option to remove various variable +attributes, and @samp{name=value} arguments to set variable attributes +and values simultaneously. + +@item +The Bash @code{hash} builtin allows a name to be associated with +an arbitrary filename, even when that filename cannot be found by +searching the @env{$PATH}, using @samp{hash -p} +(@pxref{Bourne Shell Builtins}). + +@item +Bash includes a @code{help} builtin for quick reference to shell +facilities (@pxref{Bash Builtins}). + +@item +The @code{printf} builtin is available to display formatted output +(@pxref{Bash Builtins}). + +@item +The Bash @code{read} builtin (@pxref{Bash Builtins}) +will read a line ending in @samp{\} with +the @option{-r} option, and will use the @env{REPLY} variable as a +default if no non-option arguments are supplied. +The Bash @code{read} builtin +also accepts a prompt string with the @option{-p} option and will use +Readline to obtain the line when given the @option{-e} option. +The @code{read} builtin also has additional options to control input: +the @option{-s} option will turn off echoing of input characters as +they are read, the @option{-t} option will allow @code{read} to time out +if input does not arrive within a specified number of seconds, the +@option{-n} option will allow reading only a specified number of +characters rather than a full line, and the @option{-d} option will read +until a particular character rather than newline. + +@item +The @code{return} builtin may be used to abort execution of scripts +executed with the @code{.} or @code{source} builtins +(@pxref{Bourne Shell Builtins}). + +@item +Bash includes the @code{shopt} builtin, for finer control of shell +optional capabilities (@pxref{The Shopt Builtin}), and allows these options +to be set and unset at shell invocation (@pxref{Invoking Bash}). + +@item +Bash has much more optional behavior controllable with the @code{set} +builtin (@pxref{The Set Builtin}). + +@item +The @samp{-x} (@code{xtrace}) option displays commands other than +simple commands when performing an execution trace +(@pxref{The Set Builtin}). + +@item +The @code{test} builtin (@pxref{Bourne Shell Builtins}) +is slightly different, as it implements the @sc{posix} algorithm, +which specifies the behavior based on the number of arguments. + +@item +Bash includes the @code{caller} builtin, which displays the context of +any active subroutine call (a shell function or a script executed with +the @code{.} or @code{source} builtins). This supports the bash +debugger. + +@item +The @code{trap} builtin (@pxref{Bourne Shell Builtins}) allows a +@code{DEBUG} pseudo-signal specification, similar to @code{EXIT}. +Commands specified with a @code{DEBUG} trap are executed before every +simple command, @code{for} command, @code{case} command, +@code{select} command, every arithmetic @code{for} command, and before +the first command executes in a shell function. +The @code{DEBUG} trap is not inherited by shell functions unless the +function has been given the @code{trace} attribute or the +@code{functrace} option has been enabled using the @code{shopt} builtin. +The @code{extdebug} shell option has additional effects on the +@code{DEBUG} trap. + +The @code{trap} builtin (@pxref{Bourne Shell Builtins}) allows an +@code{ERR} pseudo-signal specification, similar to @code{EXIT} and @code{DEBUG}. +Commands specified with an @code{ERR} trap are executed after a simple +command fails, with a few exceptions. +The @code{ERR} trap is not inherited by shell functions unless the +@code{-o errtrace} option to the @code{set} builtin is enabled. + +The @code{trap} builtin (@pxref{Bourne Shell Builtins}) allows a +@code{RETURN} pseudo-signal specification, similar to +@code{EXIT} and @code{DEBUG}. +Commands specified with an @code{RETURN} trap are executed before +execution resumes after a shell function or a shell script executed with +@code{.} or @code{source} returns. +The @code{RETURN} trap is not inherited by shell functions unless the +function has been given the @code{trace} attribute or the +@code{functrace} option has been enabled using the @code{shopt} builtin. + +@item +The Bash @code{type} builtin is more extensive and gives more information +about the names it finds (@pxref{Bash Builtins}). + +@item +The Bash @code{umask} builtin permits a @option{-p} option to cause +the output to be displayed in the form of a @code{umask} command +that may be reused as input (@pxref{Bourne Shell Builtins}). + +@item +Bash implements a @code{csh}-like directory stack, and provides the +@code{pushd}, @code{popd}, and @code{dirs} builtins to manipulate it +(@pxref{The Directory Stack}). +Bash also makes the directory stack visible as the value of the +@env{DIRSTACK} shell variable. + +@item +Bash interprets special backslash-escaped characters in the prompt +strings when interactive (@pxref{Printing a Prompt}). + +@item +The Bash restricted mode is more useful (@pxref{The Restricted Shell}); +the SVR4.2 shell restricted mode is too limited. + +@item +The @code{disown} builtin can remove a job from the internal shell +job table (@pxref{Job Control Builtins}) or suppress the sending +of @code{SIGHUP} to a job when the shell exits as the result of a +@code{SIGHUP}. + +@item +Bash includes a number of features to support a separate debugger for +shell scripts. + +@item +The SVR4.2 shell has two privilege-related builtins +(@code{mldmode} and @code{priv}) not present in Bash. + +@item +Bash does not have the @code{stop} or @code{newgrp} builtins. + +@item +Bash does not use the @env{SHACCT} variable or perform shell accounting. + +@item +The SVR4.2 @code{sh} uses a @env{TIMEOUT} variable like Bash uses +@env{TMOUT}. + +@end itemize + +@noindent +More features unique to Bash may be found in @ref{Bash Features}. + + +@appendixsec Implementation Differences From The SVR4.2 Shell + +Since Bash is a completely new implementation, it does not suffer from +many of the limitations of the SVR4.2 shell. For instance: + +@itemize @bullet + +@item +Bash does not fork a subshell when redirecting into or out of +a shell control structure such as an @code{if} or @code{while} +statement. + +@item +Bash does not allow unbalanced quotes. The SVR4.2 shell will silently +insert a needed closing quote at @code{EOF} under certain circumstances. +This can be the cause of some hard-to-find errors. + +@item +The SVR4.2 shell uses a baroque memory management scheme based on +trapping @code{SIGSEGV}. If the shell is started from a process with +@code{SIGSEGV} blocked (e.g., by using the @code{system()} C library +function call), it misbehaves badly. + +@item +In a questionable attempt at security, the SVR4.2 shell, +when invoked without the @option{-p} option, will alter its real +and effective @sc{uid} and @sc{gid} if they are less than some +magic threshold value, commonly 100. +This can lead to unexpected results. + +@item +The SVR4.2 shell does not allow users to trap @code{SIGSEGV}, +@code{SIGALRM}, or @code{SIGCHLD}. + +@item +The SVR4.2 shell does not allow the @env{IFS}, @env{MAILCHECK}, +@env{PATH}, @env{PS1}, or @env{PS2} variables to be unset. + +@item +The SVR4.2 shell treats @samp{^} as the undocumented equivalent of +@samp{|}. + +@item +Bash allows multiple option arguments when it is invoked (@code{-x -v}); +the SVR4.2 shell allows only one option argument (@code{-xv}). In +fact, some versions of the shell dump core if the second argument begins +with a @samp{-}. + +@item +The SVR4.2 shell exits a script if any builtin fails; Bash exits +a script only if one of the @sc{posix} special builtins fails, and +only for certain failures, as enumerated in the @sc{posix} standard. + +@item +The SVR4.2 shell behaves differently when invoked as @code{jsh} +(it turns on job control). +@end itemize + +@node Copying This Manual +@appendix Copying This Manual + +@menu +* GNU Free Documentation License:: License for copying this manual. +@end menu + +@include fdl.texi + +@node Builtin Index +@unnumbered Index of Shell Builtin Commands +@printindex bt + +@node Reserved Word Index +@unnumbered Index of Shell Reserved Words +@printindex rw + +@node Variable Index +@unnumbered Parameter and Variable Index +@printindex vr + +@node Function Index +@unnumbered Function Index +@printindex fn + +@node Concept Index +@unnumbered Concept Index +@printindex cp + +@bye diff --git a/doc/bashref.texi~ b/doc/bashref.texi~ index bc296b603..374ace287 100644 --- a/doc/bashref.texi~ +++ b/doc/bashref.texi~ @@ -111,13 +111,7 @@ reference on shell behavior. between Bash and historical versions of /bin/sh. * Copying This Manual:: Copying this manual. -* Builtin Index:: Index of Bash builtin commands. -* Reserved Word Index:: Index of Bash reserved words. -* Variable Index:: Quick reference helps you find the - variable you want. -* Function Index:: Index of bindable Readline functions. -* Concept Index:: General index for concepts described in - this manual. +* Indexes:: Various indexes for this manual. @end menu @end ifnottex @@ -4482,6 +4476,10 @@ This variable is available only in shell functions and external commands invoked by the programmable completion facilities (@pxref{Programmable Completion}). +@item COMP_KEY +The key (or final key of a key sequence) used to invoke the current +completion function. + @item COMP_WORDBREAKS The set of characters that the Readline library treats as word separators when performing word completion. @@ -7463,24 +7461,37 @@ The SVR4.2 shell behaves differently when invoked as @code{jsh} @include fdl.texi +@node Indexes +@appendix Indexes + +@menu +* Builtin Index:: Index of Bash builtin commands. +* Reserved Word Index:: Index of Bash reserved words. +* Variable Index:: Quick reference helps you find the + variable you want. +* Function Index:: Index of bindable Readline functions. +* Concept Index:: General index for concepts described in + this manual. +@end menu + @node Builtin Index -@unnumbered Index of Shell Builtin Commands +@appendixsec Index of Shell Builtin Commands @printindex bt @node Reserved Word Index -@unnumbered Index of Shell Reserved Words +@appendixsec Index of Shell Reserved Words @printindex rw @node Variable Index -@unnumbered Parameter and Variable Index +@appendixsec Parameter and Variable Index @printindex vr @node Function Index -@unnumbered Function Index +@appendixsec Function Index @printindex fn @node Concept Index -@unnumbered Concept Index +@appendixsec Concept Index @printindex cp @bye diff --git a/doc/faq.headers.mail b/doc/faq.headers.mail index f839ba693..a0ed5db06 100644 --- a/doc/faq.headers.mail +++ b/doc/faq.headers.mail @@ -1,5 +1,5 @@ -From: chet@po.cwru.edu (Chet Ramey) +From: chet.ramey@case.edu (Chet Ramey) To: bug-bash@gnu.org Subject: BASH Frequently-Asked Questions (FAQ version 3.35) -Reply-To: chet@po.cwru.edu - +Cc: chet.ramey@case.edu +Reply-To: chet.ramey@case.edu diff --git a/doc/faq.mail b/doc/faq.mail index bf9490783..e42603a3c 100644 --- a/doc/faq.mail +++ b/doc/faq.mail @@ -1,8 +1,8 @@ -From: chet@po.cwru.edu (Chet Ramey) +From: chet.ramey@case.edu (Chet Ramey) To: bug-bash@gnu.org Subject: BASH Frequently-Asked Questions (FAQ version 3.35) -Reply-To: chet@po.cwru.edu - +Cc: chet.ramey@case.edu +Reply-To: chet.ramey@case.edu Archive-name: unix-faq/shell/bash Posting-Frequency: monthly Submitted-By: chet@po.cwru.edu (Chet Ramey) diff --git a/doc/foo.html b/doc/foo.html new file mode 100644 index 000000000..92de12e1e --- /dev/null +++ b/doc/foo.html @@ -0,0 +1,10220 @@ + + +Bash Reference Manual + + + + + + + + + + +

    Bash Reference Manual

    +
    +

    Table of Contents

    + +
    + + + +
    +

    + +Next: , +Previous: (dir), +Up: (dir) + +
    + +

    Bash Features

    + +

    This text is a brief description of the features that are present in +the Bash shell (version 3.2, 30 December 2006). + +

    This is Edition 3.2, last updated 30 December 2006, +of The GNU Bash Reference Manual, +for Bash, Version 3.2. + +

    Bash contains features that appear in other popular shells, and some +features that only appear in Bash. Some of the shells that Bash has +borrowed concepts from are the Bourne Shell (sh), the Korn Shell +(ksh), and the C-shell (csh and its successor, +tcsh). The following menu breaks the features up into +categories based upon which one of these other shells inspired the +feature. + +

    This manual is meant as a brief introduction to features found in +Bash. The Bash manual page should be used as the definitive +reference on shell behavior. + +

    + +
    +

    + +Next: , +Previous: Top, +Up: Top + +
    + +

    1 Introduction

    + + + +
    +

    + + +Next: , +Up: Introduction + +
    + +

    1.1 What is Bash?

    + +

    Bash is the shell, or command language interpreter, +for the gnu operating system. +The name is an acronym for the `Bourne-Again SHell', +a pun on Stephen Bourne, the author of the direct ancestor of +the current Unix shell sh, +which appeared in the Seventh Edition Bell Labs Research version +of Unix. + +

    Bash is largely compatible with sh and incorporates useful +features from the Korn shell ksh and the C shell csh. +It is intended to be a conformant implementation of the ieee +posix Shell and Tools portion of the ieee posix +specification (ieee Standard 1003.1). +It offers functional improvements over sh for both interactive and +programming use. + +

    While the gnu operating system provides other shells, including +a version of csh, Bash is the default shell. +Like other gnu software, Bash is quite portable. It currently runs +on nearly every version of Unix and a few other operating systems − +independently-supported ports exist for ms-dos, os/2, +and Windows platforms. + +

    +

    + + +Previous: What is Bash?, +Up: Introduction + +
    + +

    1.2 What is a shell?

    + +

    At its base, a shell is simply a macro processor that executes +commands. The term macro processor means functionality where text +and symbols are expanded to create larger expressions. + +

    A Unix shell is both a command interpreter and a programming +language. As a command interpreter, the shell provides the user +interface to the rich set of gnu utilities. The programming +language features allow these utilities to be combined. +Files containing commands can be created, and become +commands themselves. These new commands have the same status as +system commands in directories such as /bin, allowing users +or groups to establish custom environments to automate their common +tasks. + +

    Shells may be used interactively or non-interactively. In +interactive mode, they accept input typed from the keyboard. +When executing non-interactively, shells execute commands read +from a file. + +

    A shell allows execution of gnu commands, both synchronously and +asynchronously. +The shell waits for synchronous commands to complete before accepting +more input; asynchronous commands continue to execute in parallel +with the shell while it reads and executes additional commands. +The redirection constructs permit +fine-grained control of the input and output of those commands. +Moreover, the shell allows control over the contents of commands' +environments. + +

    Shells also provide a small set of built-in +commands (builtins) implementing functionality impossible +or inconvenient to obtain via separate utilities. +For example, cd, break, continue, and +exec) cannot be implemented outside of the shell because +they directly manipulate the shell itself. +The history, getopts, kill, or pwd +builtins, among others, could be implemented in separate utilities, +but they are more convenient to use as builtin commands. +All of the shell builtins are described in +subsequent sections. + +

    While executing commands is essential, most of the power (and +complexity) of shells is due to their embedded programming +languages. Like any high-level language, the shell provides +variables, flow control constructs, quoting, and functions. + +

    Shells offer features geared specifically for +interactive use rather than to augment the programming language. +These interactive features include job control, command line +editing, command history and aliases. Each of these features is +described in this manual. + +

    +

    + +Next: , +Previous: Introduction, +Up: Top + +
    + +

    2 Definitions

    + +

    These definitions are used throughout the remainder of this manual. + +

    +
    POSIX
    A family of open system standards based on Unix. Bash +is primarily concerned with the Shell and Utilities portion of the +posix 1003.1 standard. + +
    blank
    A space or tab character. + +
    builtin
    A command that is implemented internally by the shell itself, rather +than by an executable program somewhere in the file system. + +
    control operator
    A word that performs a control function. It is a newline +or one of the following: +`||', `&&', `&', `;', `;;', +`|', `(', or `)'. + +
    exit status
    The value returned by a command to its caller. The value is restricted +to eight bits, so the maximum value is 255. + +
    field
    A unit of text that is the result of one of the shell expansions. After +expansion, when executing a command, the resulting fields are used as +the command name and arguments. + +
    filename
    A string of characters used to identify a file. + +
    job
    A set of processes comprising a pipeline, and any processes descended +from it, that are all in the same process group. + +
    job control
    A mechanism by which users can selectively stop (suspend) and restart +(resume) execution of processes. + +
    metacharacter
    A character that, when unquoted, separates words. A metacharacter is +a blank or one of the following characters: +`|', `&', `;', `(', `)', `<', or +`>'. + +
    name
    A word consisting solely of letters, numbers, and underscores, +and beginning with a letter or underscore. Names are used as +shell variable and function names. +Also referred to as an identifier. + +
    operator
    A control operator or a redirection operator. +See Redirections, for a list of redirection operators. + +
    process group
    A collection of related processes each having the same process +group id. + +
    process group ID
    A unique identifier that represents a process group +during its lifetime. + +
    reserved word
    A word that has a special meaning to the shell. Most reserved +words introduce shell flow control constructs, such as for and +while. + +
    return status
    A synonym for exit status. + +
    signal
    A mechanism by which a process may be notified by the kernel +of an event occurring in the system. + +
    special builtin
    A shell builtin command that has been classified as special by the +posix standard. + +
    token
    A sequence of characters considered a single unit by the shell. It is +either a word or an operator. + +
    word
    A token that is not an operator. +
    + +
    +

    + +Next: , +Previous: Definitions, +Up: Top + +
    + +

    3 Basic Shell Features

    + +

    +Bash is an acronym for `Bourne-Again SHell'. +The Bourne shell is +the traditional Unix shell originally written by Stephen Bourne. +All of the Bourne shell builtin commands are available in Bash, +The rules for evaluation and quoting are taken from the posix +specification for the `standard' Unix shell. + +

    This chapter briefly summarizes the shell's `building blocks': +commands, control structures, shell functions, shell parameters, +shell expansions, +redirections, which are a way to direct input and output from +and to named files, and how the shell executes commands. + +

    + +
    +

    + +Next: , +Up: Basic Shell Features + +
    + +

    3.1 Shell Syntax

    + +
      +
    • Shell Operation: The basic operation of the shell. +
    • Quoting: How to remove the special meaning from characters. +
    • Comments: How to specify comments. +
    + +

    When the shell reads input, it proceeds through a +sequence of operations. If the input indicates the beginning of a +comment, the shell ignores the comment symbol (`#'), and the rest +of that line. + +

    Otherwise, roughly speaking, the shell reads its input and +divides the input into words and operators, employing the quoting rules +to select which meanings to assign various words and characters. + +

    The shell then parses these tokens into commands and other constructs, +removes the special meaning of certain words or characters, expands +others, redirects input and output as needed, executes the specified +command, waits for the command's exit status, and makes that exit status +available for further inspection or processing. + +

    +

    + +Next: , +Up: Shell Syntax + +
    + +

    3.1.1 Shell Operation

    + +

    The following is a brief description of the shell's operation when it +reads and executes a command. Basically, the shell does the +following: + +

      +
    1. Reads its input from a file (see Shell Scripts), from a string +supplied as an argument to the -c invocation option +(see Invoking Bash), or from the user's terminal. + +
    2. Breaks the input into words and operators, obeying the quoting rules +described in Quoting. These tokens are separated by +metacharacters. Alias expansion is performed by this step +(see Aliases). + +
    3. Parses the tokens into simple and compound commands +(see Shell Commands). + +
    4. Performs the various shell expansions (see Shell Expansions), breaking +the expanded tokens into lists of filenames (see Filename Expansion) +and commands and arguments. + +
    5. Performs any necessary redirections (see Redirections) and removes +the redirection operators and their operands from the argument list. + +
    6. Executes the command (see Executing Commands). + +
    7. Optionally waits for the command to complete and collects its exit +status (see Exit Status). + +
    + +
    +

    + +Next: , +Previous: Shell Operation, +Up: Shell Syntax + +
    + +

    3.1.2 Quoting

    + +

    + +

      +
    • Escape Character: How to remove the special meaning from a single + character. +
    • Single Quotes: How to inhibit all interpretation of a sequence + of characters. +
    • Double Quotes: How to suppress most of the interpretation of a + sequence of characters. +
    • ANSI-C Quoting: How to expand ANSI-C sequences in quoted strings. +
    • Locale Translation: How to translate strings into different languages. +
    + +

    Quoting is used to remove the special meaning of certain +characters or words to the shell. Quoting can be used to +disable special treatment for special characters, to prevent +reserved words from being recognized as such, and to prevent +parameter expansion. + +

    Each of the shell metacharacters (see Definitions) +has special meaning to the shell and must be quoted if it is to +represent itself. +When the command history expansion facilities are being used +(see History Interaction), the +history expansion character, usually `!', must be quoted +to prevent history expansion. See Bash History Facilities, for +more details concerning history expansion. + +

    There are three quoting mechanisms: the +escape character, single quotes, and double quotes. + +

    +

    + +Next: , +Up: Quoting + +
    + +
    3.1.2.1 Escape Character
    + +

    A non-quoted backslash `\' is the Bash escape character. +It preserves the literal value of the next character that follows, +with the exception of newline. If a \newline pair +appears, and the backslash itself is not quoted, the \newline +is treated as a line continuation (that is, it is removed from +the input stream and effectively ignored). + +

    +

    + +Next: , +Previous: Escape Character, +Up: Quoting + +
    + +
    3.1.2.2 Single Quotes
    + +

    Enclosing characters in single quotes (`'') preserves the literal value +of each character within the quotes. A single quote may not occur +between single quotes, even when preceded by a backslash. + +

    +

    + +Next: , +Previous: Single Quotes, +Up: Quoting + +
    + +
    3.1.2.3 Double Quotes
    + +

    Enclosing characters in double quotes (`"') preserves the literal value +of all characters within the quotes, with the exception of +`$', ``', `\', +and, when history expansion is enabled, `!'. +The characters `$' and ``' +retain their special meaning within double quotes (see Shell Expansions). +The backslash retains its special meaning only when followed by one of +the following characters: +`$', ``', `"', `\', or newline. +Within double quotes, backslashes that are followed by one of these +characters are removed. Backslashes preceding characters without a +special meaning are left unmodified. +A double quote may be quoted within double quotes by preceding it with +a backslash. +If enabled, history expansion will be performed unless an `!' +appearing in double quotes is escaped using a backslash. +The backslash preceding the `!' is not removed. + +

    The special parameters `*' and `@' have special meaning +when in double quotes (see Shell Parameter Expansion). + +

    +

    + + +Next: , +Previous: Double Quotes, +Up: Quoting + +
    + +
    3.1.2.4 ANSI-C Quoting
    + +

    +Words of the form $'string' are treated specially. The +word expands to string, with backslash-escaped characters replaced +as specified by the ANSI C standard. Backslash escape sequences, if +present, are decoded as follows: + +

    +
    \a
    alert (bell) +
    \b
    backspace +
    \e
    an escape character (not ANSI C) +
    \f
    form feed +
    \n
    newline +
    \r
    carriage return +
    \t
    horizontal tab +
    \v
    vertical tab +
    \\
    backslash +
    \'
    single quote +
    \nnn
    the eight-bit character whose value is the octal value nnn +(one to three digits) +
    \xHH
    the eight-bit character whose value is the hexadecimal value HH +(one or two hex digits) +
    \cx
    a control-x character +
    + +

    The expanded result is single-quoted, as if the dollar sign had not +been present. + +

    +

    + +Previous: ANSI-C Quoting, +Up: Quoting + +
    + +
    3.1.2.5 Locale-Specific Translation
    + +

    +A double-quoted string preceded by a dollar sign (`$') will cause +the string to be translated according to the current locale. +If the current locale is C or POSIX, the dollar sign +is ignored. +If the string is translated and replaced, the replacement is +double-quoted. + +

    Some systems use the message catalog selected by the LC_MESSAGES +shell variable. Others create the name of the message catalog from the +value of the TEXTDOMAIN shell variable, possibly adding a +suffix of `.mo'. If you use the TEXTDOMAIN variable, you +may need to set the TEXTDOMAINDIR variable to the location of +the message catalog files. Still others use both variables in this +fashion: +TEXTDOMAINDIR/LC_MESSAGES/LC_MESSAGES/TEXTDOMAIN.mo. + +

    +

    + +Previous: Quoting, +Up: Shell Syntax + +
    + +

    3.1.3 Comments

    + +

    +In a non-interactive shell, or an interactive shell in which the +interactive_comments option to the shopt +builtin is enabled (see The Shopt Builtin), +a word beginning with `#' +causes that word and all remaining characters on that line to +be ignored. An interactive shell without the interactive_comments +option enabled does not allow comments. The interactive_comments +option is on by default in interactive shells. +See Interactive Shells, for a description of what makes +a shell interactive. + +

    +

    + +Next: , +Previous: Shell Syntax, +Up: Basic Shell Features + +
    + +

    3.2 Shell Commands

    + +

    +A simple shell command such as echo a b c consists of the command +itself followed by arguments, separated by spaces. + +

    More complex shell commands are composed of simple commands arranged together +in a variety of ways: in a pipeline in which the output of one command +becomes the input of a second, in a loop or conditional construct, or in +some other grouping. + +

    + +
    +

    + +Next: , +Up: Shell Commands + +
    + +

    3.2.1 Simple Commands

    + +

    +A simple command is the kind of command encountered most often. +It's just a sequence of words separated by blanks, terminated +by one of the shell's control operators (see Definitions). The +first word generally specifies a command to be executed, with the +rest of the words being that command's arguments. + +

    The return status (see Exit Status) of a simple command is +its exit status as provided +by the posix 1003.1 waitpid function, or 128+n if +the command was terminated by signal n. + +

    +

    + +Next: , +Previous: Simple Commands, +Up: Shell Commands + +
    + +

    3.2.2 Pipelines

    + +

    +A pipeline is a sequence of simple commands separated by +`|'. + +

    The format for a pipeline is +

         [time [-p]] [!] command1 [| command2 ...]
+
    +

    The output of each command in the pipeline is connected via a pipe +to the input of the next command. +That is, each command reads the previous command's output. + +

    The reserved word time causes timing statistics +to be printed for the pipeline once it finishes. +The statistics currently consist of elapsed (wall-clock) time and +user and system time consumed by the command's execution. +The -p option changes the output format to that specified +by posix. +The TIMEFORMAT variable may be set to a format string that +specifies how the timing information should be displayed. +See Bash Variables, for a description of the available formats. +The use of time as a reserved word permits the timing of +shell builtins, shell functions, and pipelines. An external +time command cannot time these easily. + +

    If the pipeline is not executed asynchronously (see Lists), the +shell waits for all commands in the pipeline to complete. + +

    Each command in a pipeline is executed in its own subshell +(see Command Execution Environment). The exit +status of a pipeline is the exit status of the last command in the +pipeline, unless the pipefail option is enabled +(see The Set Builtin). +If pipefail is enabled, the pipeline's return status is the +value of the last (rightmost) command to exit with a non-zero status, +or zero if all commands exit successfully. +If the reserved word `!' precedes the pipeline, the +exit status is the logical negation of the exit status as described +above. +The shell waits for all commands in the pipeline to terminate before +returning a value. + +

    +

    + +Next: , +Previous: Pipelines, +Up: Shell Commands + +
    + +

    3.2.3 Lists of Commands

    + +

    +A list is a sequence of one or more pipelines separated by one +of the operators `;', `&', `&&', or `||', +and optionally terminated by one of `;', `&', or a +newline. + +

    Of these list operators, `&&' and `||' +have equal precedence, followed by `;' and `&', +which have equal precedence. + +

    A sequence of one or more newlines may appear in a list +to delimit commands, equivalent to a semicolon. + +

    If a command is terminated by the control operator `&', +the shell executes the command asynchronously in a subshell. +This is known as executing the command in the background. +The shell does not wait for the command to finish, and the return +status is 0 (true). +When job control is not active (see Job Control), +the standard input for asynchronous commands, in the absence of any +explicit redirections, is redirected from /dev/null. + +

    Commands separated by a `;' are executed sequentially; the shell +waits for each command to terminate in turn. The return status is the +exit status of the last command executed. + +

    The control operators `&&' and `||' +denote and lists and or lists, respectively. +An and list has the form +

         command1 && command2
+
    +

    command2 is executed if, and only if, command1 +returns an exit status of zero. + +

    An or list has the form +

         command1 || command2
+
    +

    command2 is executed if, and only if, command1 +returns a non-zero exit status. + +

    The return status of +and and or lists is the exit status of the last command +executed in the list. + +

    +

    + +Previous: Lists, +Up: Shell Commands + +
    + +

    3.2.4 Compound Commands

    + +

    + +

    + +

    Compound commands are the shell programming constructs. +Each construct begins with a reserved word or control operator and is +terminated by a corresponding reserved word or operator. +Any redirections (see Redirections) associated with a compound command +apply to all commands within that compound command unless explicitly overridden. + +

    Bash provides looping constructs, conditional commands, and mechanisms +to group commands and execute them as a unit. + +

    +

    + +Next: , +Up: Compound Commands + +
    + +
    3.2.4.1 Looping Constructs
    + +

    +Bash supports the following looping constructs. + +

    Note that wherever a `;' appears in the description of a +command's syntax, it may be replaced with one or more newlines. + +

    +
    until
    The syntax of the until command is: + 
              until test-commands; do consequent-commands; done
+
    +

    Execute consequent-commands as long as +test-commands has an exit status which is not zero. +The return status is the exit status of the last command executed +in consequent-commands, or zero if none was executed. + +

    while
    The syntax of the while command is: + 
              while test-commands; do consequent-commands; done
+
    +

    Execute consequent-commands as long as +test-commands has an exit status of zero. +The return status is the exit status of the last command executed +in consequent-commands, or zero if none was executed. + +

    for
    The syntax of the for command is: + + 
              for name [in words ...]; do commands; done
+
    +

    Expand words, and execute commands once for each member +in the resultant list, with name bound to the current member. +If `in words' is not present, the for command +executes the commands once for each positional parameter that is +set, as if `in "$@"' had been specified +(see Special Parameters). +The return status is the exit status of the last command that executes. +If there are no items in the expansion of words, no commands are +executed, and the return status is zero. + +

    An alternate form of the for command is also supported: + + 

              for (( expr1 ; expr2 ; expr3 )) ; do commands ; done
+
    +

    First, the arithmetic expression expr1 is evaluated according +to the rules described below (see Shell Arithmetic). +The arithmetic expression expr2 is then evaluated repeatedly +until it evaluates to zero. +Each time expr2 evaluates to a non-zero value, commands are +executed and the arithmetic expression expr3 is evaluated. +If any expression is omitted, it behaves as if it evaluates to 1. +The return value is the exit status of the last command in list +that is executed, or false if any of the expressions is invalid. + +

    + +

    The break and continue builtins (see Bourne Shell Builtins) +may be used to control loop execution. + +

    +

    + +Next: , +Previous: Looping Constructs, +Up: Compound Commands + +
    + +
    3.2.4.2 Conditional Constructs
    + +

    +

    +
    if
    The syntax of the if command is: + + 
              if test-commands; then
+            consequent-commands;
+          [elif more-test-commands; then
+            more-consequents;]
+          [else alternate-consequents;]
+          fi
+
    +

    The test-commands list is executed, and if its return status is zero, +the consequent-commands list is executed. +If test-commands returns a non-zero status, each elif list +is executed in turn, and if its exit status is zero, +the corresponding more-consequents is executed and the +command completes. +If `else alternate-consequents' is present, and +the final command in the final if or elif clause +has a non-zero exit status, then alternate-consequents is executed. +The return status is the exit status of the last command executed, or +zero if no condition tested true. + +

    case
    The syntax of the case command is: + + 
              case word in [ [(] pattern [| pattern]...) command-list ;;]... esac
+
    +

    case will selectively execute the command-list corresponding to +the first pattern that matches word. +If the shell option nocasematch +(see the description of shopt in The Shopt Builtin) +is enabled, the match is performed without regard to the case +of alphabetic characters. +The `|' is used to separate multiple patterns, and the `)' +operator terminates a pattern list. +A list of patterns and an associated command-list is known +as a clause. Each clause must be terminated with `;;'. +The word undergoes tilde expansion, parameter expansion, command +substitution, arithmetic expansion, and quote removal before matching is +attempted. Each pattern undergoes tilde expansion, parameter +expansion, command substitution, and arithmetic expansion. + +

    There may be an arbitrary number of case clauses, each terminated +by a `;;'. The first pattern that matches determines the +command-list that is executed. + +

    Here is an example using case in a script that could be used to +describe one interesting feature of an animal: + + 

              echo -n "Enter the name of an animal: "
+          read ANIMAL
+          echo -n "The $ANIMAL has "
+          case $ANIMAL in
+            horse | dog | cat) echo -n "four";;
+            man | kangaroo ) echo -n "two";;
+            *) echo -n "an unknown number of";;
+          esac
+          echo " legs."
+
    +

    The return status is zero if no pattern is matched. Otherwise, the +return status is the exit status of the command-list executed. + +

    select
    +The select construct allows the easy generation of menus. +It has almost the same syntax as the for command: + + 
              select name [in words ...]; do commands; done
+
    +

    The list of words following in is expanded, generating a list +of items. The set of expanded words is printed on the standard +error output stream, each preceded by a number. If the +`in words' is omitted, the positional parameters are printed, +as if `in "$@"' had been specified. +The PS3 prompt is then displayed and a line is read from the +standard input. +If the line consists of a number corresponding to one of the displayed +words, then the value of name is set to that word. +If the line is empty, the words and prompt are displayed again. +If EOF is read, the select command completes. +Any other value read causes name to be set to null. +The line read is saved in the variable REPLY. + +

    The commands are executed after each selection until a +break command is executed, at which +point the select command completes. + +

    Here is an example that allows the user to pick a filename from the +current directory, and displays the name and index of the file +selected. + + 

              select fname in *;
+          do
+          	echo you picked $fname \($REPLY\)
+          	break;
+          done
+
    +
    ((...))
    + 
              (( expression ))
+
    +

    The arithmetic expression is evaluated according to the rules +described below (see Shell Arithmetic). +If the value of the expression is non-zero, the return status is 0; +otherwise the return status is 1. This is exactly equivalent to + 

              let "expression"
+
    +

    See Bash Builtins, for a full description of the let builtin. + +

    [[...]]
    + 
              [[ expression ]]
+
    +

    Return a status of 0 or 1 depending on the evaluation of +the conditional expression expression. +Expressions are composed of the primaries described below in +Bash Conditional Expressions. +Word splitting and filename expansion are not performed on the words +between the `[[' and `]]'; tilde expansion, parameter and +variable expansion, arithmetic expansion, command substitution, process +substitution, and quote removal are performed. +Conditional operators such as `-f' must be unquoted to be recognized +as primaries. + +

    When the `==' and `!=' operators are used, the string to the +right of the operator is considered a pattern and matched according +to the rules described below in Pattern Matching. +If the shell option nocasematch +(see the description of shopt in The Shopt Builtin) +is enabled, the match is performed without regard to the case +of alphabetic characters. +The return value is 0 if the string matches (`==') or does not +match (`!=')the pattern, and 1 otherwise. +Any part of the pattern may be quoted to force it to be matched as a +string. + +

    An additional binary operator, `=~', is available, with the same +precedence as `==' and `!='. +When it is used, the string to the right of the operator is considered +an extended regular expression and matched accordingly (as in regex3)). +The return value is 0 if the string matches +the pattern, and 1 otherwise. +If the regular expression is syntactically incorrect, the conditional +expression's return value is 2. +If the shell option nocasematch +(see the description of shopt in The Shopt Builtin) +is enabled, the match is performed without regard to the case +of alphabetic characters. +Substrings matched by parenthesized subexpressions within the regular +expression are saved in the array variable BASH_REMATCH. +The element of BASH_REMATCH with index 0 is the portion of the string +matching the entire regular expression. +The element of BASH_REMATCH with index n is the portion of the +string matching the nth parenthesized subexpression. + +

    Expressions may be combined using the following operators, listed +in decreasing order of precedence: + +

    +
    ( expression )
    Returns the value of expression. +This may be used to override the normal precedence of operators. + +
    ! expression
    True if expression is false. + +
    expression1 && expression2
    True if both expression1 and expression2 are true. + +
    expression1 || expression2
    True if either expression1 or expression2 is true. +
    + The && and || operators do not evaluate expression2 if the +value of expression1 is sufficient to determine the return +value of the entire conditional expression. + +
    + +
    +

    + +Previous: Conditional Constructs, +Up: Compound Commands + +
    + +
    3.2.4.3 Grouping Commands
    + +

    +Bash provides two ways to group a list of commands to be executed +as a unit. When commands are grouped, redirections may be applied +to the entire command list. For example, the output of all the +commands in the list may be redirected to a single stream. + +

    +
    ()
    + 
              ( list )
+
    +

    Placing a list of commands between parentheses causes a subshell +environment to be created (see Command Execution Environment), and each +of the commands in list to be executed in that subshell. Since the +list is executed in a subshell, variable assignments do not remain in +effect after the subshell completes. + +

    {}
    + 
              { list; }
+
    +

    Placing a list of commands between curly braces causes the list to +be executed in the current shell context. No subshell is created. +The semicolon (or newline) following list is required. +

    + +

    In addition to the creation of a subshell, there is a subtle difference +between these two constructs due to historical reasons. The braces +are reserved words, so they must be separated from the list +by blanks. The parentheses are operators, and are +recognized as separate tokens by the shell even if they are not separated +from the list by whitespace. + +

    The exit status of both of these constructs is the exit status of +list. + +

    +

    + +Next: , +Previous: Shell Commands, +Up: Basic Shell Features + +
    + +

    3.3 Shell Functions

    + +

    +Shell functions are a way to group commands for later execution +using a single name for the group. They are executed just like +a "regular" command. +When the name of a shell function is used as a simple command name, +the list of commands associated with that function name is executed. +Shell functions are executed in the current +shell context; no new process is created to interpret them. + +

    Functions are declared using this syntax: + +

         [ function ] name () compound-command [ redirections ]
+
    +

    This defines a shell function named name. The reserved +word function is optional. +If the function reserved +word is supplied, the parentheses are optional. +The body of the function is the compound command +compound-command (see Compound Commands). +That command is usually a list enclosed between { and }, but +may be any compound command listed above. +compound-command is executed whenever name is specified as the +name of a command. +Any redirections (see Redirections) associated with the shell function +are performed when the function is executed. + +

    A function definition may be deleted using the -f option to the +unset builtin (see Bourne Shell Builtins). + +

    The exit status of a function definition is zero unless a syntax error +occurs or a readonly function with the same name already exists. +When executed, the exit status of a function is the exit status of the +last command executed in the body. + +

    Note that for historical reasons, in the most common usage the curly braces +that surround the body of the function must be separated from the body by +blanks or newlines. +This is because the braces are reserved words and are only recognized +as such when they are separated by whitespace. +Also, when using the braces, the list must be terminated by a semicolon, +a `&', or a newline. + +

    When a function is executed, the arguments to the +function become the positional parameters +during its execution (see Positional Parameters). +The special parameter `#' that expands to the number of +positional parameters is updated to reflect the change. +Special parameter 0 is unchanged. +The first element of the FUNCNAME variable is set to the +name of the function while the function is executing. +All other aspects of the shell execution +environment are identical between a function and its caller +with the exception that the DEBUG and RETURN traps +are not inherited unless the function has been given the +trace attribute using the declare builtin or +the -o functrace option has been enabled with +the set builtin, +(in which case all functions inherit the DEBUG and RETURN traps). +See Bourne Shell Builtins, for the description of the +trap builtin. + +

    If the builtin command return +is executed in a function, the function completes and +execution resumes with the next command after the function +call. +Any command associated with the RETURN trap is executed +before execution resumes. +When a function completes, the values of the +positional parameters and the special parameter `#' +are restored to the values they had prior to the function's +execution. If a numeric argument is given to return, +that is the function's return status; otherwise the function's +return status is the exit status of the last command executed +before the return. + +

    Variables local to the function may be declared with the +local builtin. These variables are visible only to +the function and the commands it invokes. + +

    Function names and definitions may be listed with the +-f option to the declare or typeset +builtin commands (see Bash Builtins). +The -F option to declare or typeset +will list the function names only +(and optionally the source file and line number, if the extdebug +shell option is enabled). +Functions may be exported so that subshells +automatically have them defined with the +-f option to the export builtin +(see Bourne Shell Builtins). +Note that shell functions and variables with the same name may result +in multiple identically-named entries in the environment passed to the +shell's children. +Care should be taken in cases where this may cause a problem. + +

    Functions may be recursive. No limit is placed on the number of +recursive calls. + +

    +

    + +Next: , +Previous: Shell Functions, +Up: Basic Shell Features + +
    + +

    3.4 Shell Parameters

    + +

    + +

    + +

    A parameter is an entity that stores values. +It can be a name, a number, or one of the special characters +listed below. +A variable is a parameter denoted by a name. +A variable has a value and zero or more attributes. +Attributes are assigned using the declare builtin command +(see the description of the declare builtin in Bash Builtins). + +

    A parameter is set if it has been assigned a value. The null string is +a valid value. Once a variable is set, it may be unset only by using +the unset builtin command. + +

    A variable may be assigned to by a statement of the form +

         name=[value]
+
    +

    If value +is not given, the variable is assigned the null string. All +values undergo tilde expansion, parameter and variable expansion, +command substitution, arithmetic expansion, and quote +removal (detailed below). If the variable has its integer +attribute set, then value +is evaluated as an arithmetic expression even if the $((...)) +expansion is not used (see Arithmetic Expansion). +Word splitting is not performed, with the exception +of "$@" as explained below. +Filename expansion is not performed. +Assignment statements may also appear as arguments to the +alias, +declare, typeset, export, readonly, +and local builtin commands. + +

    In the context where an assignment statement is assigning a value +to a shell variable or array index (see Arrays), the `+=' +operator can be used to +append to or add to the variable's previous value. +When `+=' is applied to a variable for which the integer attribute +has been set, value is evaluated as an arithmetic expression and +added to the variable's current value, which is also evaluated. +When `+=' is applied to an array variable using compound assignment +(see Arrays), the +variable's value is not unset (as it is when using `='), and new +values are appended to the array beginning at one greater than the array's +maximum index. +When applied to a string-valued variable, value is expanded and +appended to the variable's value. + +

    +

    + +Next: , +Up: Shell Parameters + +
    + +

    3.4.1 Positional Parameters

    + +

    +A positional parameter is a parameter denoted by one or more +digits, other than the single digit 0. Positional parameters are +assigned from the shell's arguments when it is invoked, +and may be reassigned using the set builtin command. +Positional parameter N may be referenced as ${N}, or +as $N when N consists of a single digit. +Positional parameters may not be assigned to with assignment statements. +The set and shift builtins are used to set and +unset them (see Shell Builtin Commands). +The positional parameters are +temporarily replaced when a shell function is executed +(see Shell Functions). + +

    When a positional parameter consisting of more than a single +digit is expanded, it must be enclosed in braces. + +

    +

    + +Previous: Positional Parameters, +Up: Shell Parameters + +
    + +

    3.4.2 Special Parameters

    + +

    +The shell treats several parameters specially. These parameters may +only be referenced; assignment to them is not allowed. + +

    +
    *
    Expands to the positional parameters, starting from one. When the +expansion occurs within double quotes, it expands to a single word +with the value of each parameter separated by the first character +of the IFS +special variable. That is, "$*" is equivalent +to "$1c$2c...", where c +is the first character of the value of the IFS +variable. +If IFS is unset, the parameters are separated by spaces. +If IFS is null, the parameters are joined without intervening +separators. + +
    @
    Expands to the positional parameters, starting from one. When the +expansion occurs within double quotes, each parameter expands to a +separate word. That is, "$@" is equivalent to +"$1" "$2" .... +If the double-quoted expansion occurs within a word, the expansion of +the first parameter is joined with the beginning part of the original +word, and the expansion of the last parameter is joined with the last +part of the original word. +When there are no positional parameters, "$@" and +$@ +expand to nothing (i.e., they are removed). + +
    #
    Expands to the number of positional parameters in decimal. + +
    ?
    Expands to the exit status of the most recently executed foreground +pipeline. + +
    -
    (A hyphen.) Expands to the current option flags as specified upon +invocation, by the set +builtin command, or those set by the shell itself +(such as the -i option). + +
    $
    Expands to the process id of the shell. In a () subshell, it +expands to the process id of the invoking shell, not the subshell. + +
    !
    Expands to the process id of the most recently executed background +(asynchronous) command. + +
    0
    Expands to the name of the shell or shell script. This is set at +shell initialization. If Bash is invoked with a file of commands +(see Shell Scripts), $0 is set to the name of that file. +If Bash is started with the -c option (see Invoking Bash), +then $0 is set to the first argument after the string to be +executed, if one is present. Otherwise, it is set +to the filename used to invoke Bash, as given by argument zero. + +
    _
    (An underscore.) +At shell startup, set to the absolute pathname used to invoke the +shell or shell script being executed as passed in the environment +or argument list. +Subsequently, expands to the last argument to the previous command, +after expansion. +Also set to the full pathname used to invoke each command executed +and placed in the environment exported to that command. +When checking mail, this parameter holds the name of the mail file. +
    + +
    +

    + +Next: , +Previous: Shell Parameters, +Up: Basic Shell Features + +
    + +

    3.5 Shell Expansions

    + +

    +Expansion is performed on the command line after it has been split into +tokens. There are seven kinds of expansion performed: +

      +
    • brace expansion +
    • tilde expansion +
    • parameter and variable expansion +
    • command substitution +
    • arithmetic expansion +
    • word splitting +
    • filename expansion +
    + + + +

    The order of expansions is: brace expansion, tilde expansion, +parameter, variable, and arithmetic expansion and +command substitution +(done in a left-to-right fashion), word splitting, and filename +expansion. + +

    On systems that can support it, there is an additional expansion +available: process substitution. This is performed at the +same time as parameter, variable, and arithmetic expansion and +command substitution. + +

    Only brace expansion, word splitting, and filename expansion +can change the number of words of the expansion; other expansions +expand a single word to a single word. +The only exceptions to this are the expansions of +"$@" (see Special Parameters) and "${name[@]}" +(see Arrays). + +

    After all expansions, quote removal (see Quote Removal) +is performed. + +

    +

    + +Next: , +Up: Shell Expansions + +
    + +

    3.5.1 Brace Expansion

    + +

    +Brace expansion is a mechanism by which arbitrary strings may be generated. +This mechanism is similar to +filename expansion (see Filename Expansion), +but the file names generated need not exist. +Patterns to be brace expanded take the form of an optional preamble, +followed by either a series of comma-separated strings or a seqeunce expression +between a pair of braces, +followed by an optional postscript. +The preamble is prefixed to each string contained within the braces, and +the postscript is then appended to each resulting string, expanding left +to right. + +

    Brace expansions may be nested. +The results of each expanded string are not sorted; left to right order +is preserved. +For example, +

         bash$ echo a{d,c,b}e
+     ade ace abe
+
    +

    A sequence expression takes the form {x..y}, +where x and y are either integers or single characters. +When integers are supplied, the expression expands to each number between +x and y, inclusive. +When characters are supplied, the expression expands to each character +lexicographically between x and y, inclusive. Note that +both x and y must be of the same type. + +

    Brace expansion is performed before any other expansions, +and any characters special to other expansions are preserved +in the result. It is strictly textual. Bash +does not apply any syntactic interpretation to the context of the +expansion or the text between the braces. +To avoid conflicts with parameter expansion, the string `${' +is not considered eligible for brace expansion. + +

    A correctly-formed brace expansion must contain unquoted opening +and closing braces, and at least one unquoted comma or a valid +sequence expression. +Any incorrectly formed brace expansion is left unchanged. + +

    A { or `,' may be quoted with a backslash to prevent its +being considered part of a brace expression. +To avoid conflicts with parameter expansion, the string `${' +is not considered eligible for brace expansion. + +

    This construct is typically used as shorthand when the common +prefix of the strings to be generated is longer than in the +above example: +

         mkdir /usr/local/src/bash/{old,new,dist,bugs}
+
    +

    or +

         chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}}
+
    +
    +

    + +Next: , +Previous: Brace Expansion, +Up: Shell Expansions + +
    + +

    3.5.2 Tilde Expansion

    + +

    +If a word begins with an unquoted tilde character (`~'), all of the +characters up to the first unquoted slash (or all characters, +if there is no unquoted slash) are considered a tilde-prefix. +If none of the characters in the tilde-prefix are quoted, the +characters in the tilde-prefix following the tilde are treated as a +possible login name. +If this login name is the null string, the tilde is replaced with the +value of the HOME shell variable. +If HOME is unset, the home directory of the user executing the +shell is substituted instead. +Otherwise, the tilde-prefix is replaced with the home directory +associated with the specified login name. + +

    If the tilde-prefix is `~+', the value of +the shell variable PWD replaces the tilde-prefix. +If the tilde-prefix is `~-', the value of the shell variable +OLDPWD, if it is set, is substituted. + +

    If the characters following the tilde in the tilde-prefix consist of a +number N, optionally prefixed by a `+' or a `-', +the tilde-prefix is replaced with the +corresponding element from the directory stack, as it would be displayed +by the dirs builtin invoked with the characters following tilde +in the tilde-prefix as an argument (see The Directory Stack). +If the tilde-prefix, sans the tilde, consists of a number without a +leading `+' or `-', `+' is assumed. + +

    If the login name is invalid, or the tilde expansion fails, the word is +left unchanged. + +

    Each variable assignment is checked for unquoted tilde-prefixes immediately +following a `:' or the first `='. +In these cases, tilde expansion is also performed. +Consequently, one may use file names with tildes in assignments to +PATH, MAILPATH, and CDPATH, +and the shell assigns the expanded value. + +

    The following table shows how Bash treats unquoted tilde-prefixes: + +

    +
    ~
    The value of $HOME +
    ~/foo
    $HOME/foo + +
    ~fred/foo
    The subdirectory foo of the home directory of the user +fred + +
    ~+/foo
    $PWD/foo + +
    ~-/foo
    ${OLDPWD-'~-'}/foo + +
    ~N
    The string that would be displayed by `dirs +N' + +
    ~+N
    The string that would be displayed by `dirs +N' + +
    ~-N
    The string that would be displayed by `dirs -N' + +
    + +
    +

    + +Next: , +Previous: Tilde Expansion, +Up: Shell Expansions + +
    + +

    3.5.3 Shell Parameter Expansion

    + +

    +The `$' character introduces parameter expansion, +command substitution, or arithmetic expansion. The parameter name +or symbol to be expanded may be enclosed in braces, which +are optional but serve to protect the variable to be expanded from +characters immediately following it which could be +interpreted as part of the name. + +

    When braces are used, the matching ending brace is the first `}' +not escaped by a backslash or within a quoted string, and not within an +embedded arithmetic expansion, command substitution, or parameter +expansion. + +

    The basic form of parameter expansion is ${parameter}. +The value of parameter is substituted. The braces are required +when parameter +is a positional parameter with more than one digit, +or when parameter +is followed by a character that is not to be +interpreted as part of its name. + +

    If the first character of parameter is an exclamation point, +a level of variable indirection is introduced. +Bash uses the value of the variable formed from the rest of +parameter as the name of the variable; this variable is then +expanded and that value is used in the rest of the substitution, rather +than the value of parameter itself. +This is known as indirect expansion. +The exceptions to this are the expansions of ${!prefix*} +and ${!name[@]} +described below. +The exclamation point must immediately follow the left brace in order to +introduce indirection. + +

    In each of the cases below, word is subject to tilde expansion, +parameter expansion, command substitution, and arithmetic expansion. + +

    When not performing substring expansion, Bash tests for a parameter +that is unset or null; omitting the colon results in a test only for a +parameter that is unset. Put another way, if the colon is included, +the operator tests for both existence and that the value is not null; +if the colon is omitted, the operator tests only for existence. + +

    +
    ${parameter:−word}
    If parameter is unset or null, the expansion of +word is substituted. Otherwise, the value of +parameter is substituted. + +
    ${parameter:=word}
    If parameter +is unset or null, the expansion of word +is assigned to parameter. +The value of parameter is then substituted. +Positional parameters and special parameters may not be assigned to +in this way. + +
    ${parameter:?word}
    If parameter +is null or unset, the expansion of word (or a message +to that effect if word +is not present) is written to the standard error and the shell, if it +is not interactive, exits. Otherwise, the value of parameter is +substituted. + +
    ${parameter:+word}
    If parameter +is null or unset, nothing is substituted, otherwise the expansion of +word is substituted. + +
    ${parameter:offset}
    ${parameter:offset:length}
    Expands to up to length characters of parameter +starting at the character specified by offset. +If length is omitted, expands to the substring of +parameter starting at the character specified by offset. +length and offset are arithmetic expressions +(see Shell Arithmetic). +This is referred to as Substring Expansion. + +

    length must evaluate to a number greater than or equal to zero. +If offset evaluates to a number less than zero, the value +is used as an offset from the end of the value of parameter. +If parameter is `@', the result is length positional +parameters beginning at offset. +If parameter is an array name indexed by `@' or `*', +the result is the length +members of the array beginning with ${parameter[offset]}. +A negative offset is taken relative to one greater than the maximum +index of the specified array. +Note that a negative offset must be separated from the colon by at least +one space to avoid being confused with the `:-' expansion. +Substring indexing is zero-based unless the positional parameters +are used, in which case the indexing starts at 1 by default. +If offset is 0, and the positional parameters are used, $@ is +prefixed to the list. + +

    ${!prefix*}
    ${!prefix@}
    Expands to the names of variables whose names begin with prefix, +separated by the first character of the IFS special variable. +When `@' is used and the expansion appears within double quotes, each +variable name expands to a separate word. + +
    ${!name[@]}
    ${!name[*]}
    If name is an array variable, expands to the list of array indices +(keys) assigned in name. +If name is not an array, expands to 0 if name is set and null +otherwise. +When `@' is used and the expansion appears within double quotes, each +key expands to a separate word. + +
    ${#parameter}
    The length in characters of the expanded value of parameter is +substituted. +If parameter is `*' or `@', the value substituted +is the number of positional parameters. +If parameter is an array name subscripted by `*' or `@', +the value substituted is the number of elements in the array. + +
    ${parameter#word}
    ${parameter##word}
    The word +is expanded to produce a pattern just as in filename +expansion (see Filename Expansion). If the pattern matches +the beginning of the expanded value of parameter, +then the result of the expansion is the expanded value of parameter +with the shortest matching pattern (the `#' case) or the +longest matching pattern (the `##' case) deleted. +If parameter is `@' or `*', +the pattern removal operation is applied to each positional +parameter in turn, and the expansion is the resultant list. +If parameter is an array variable subscripted with +`@' or `*', +the pattern removal operation is applied to each member of the +array in turn, and the expansion is the resultant list. + +
    ${parameter%word}
    ${parameter%%word}
    The word is expanded to produce a pattern just as in +filename expansion. +If the pattern matches a trailing portion of the expanded value of +parameter, then the result of the expansion is the value of +parameter with the shortest matching pattern (the `%' case) +or the longest matching pattern (the `%%' case) deleted. +If parameter is `@' or `*', +the pattern removal operation is applied to each positional +parameter in turn, and the expansion is the resultant list. +If parameter +is an array variable subscripted with `@' or `*', +the pattern removal operation is applied to each member of the +array in turn, and the expansion is the resultant list. + +
    ${parameter/pattern/string}
    +The pattern is expanded to produce a pattern just as in +filename expansion. +Parameter is expanded and the longest match of pattern +against its value is replaced with string. +If pattern begins with `/', all matches of pattern are +replaced with string. Normally only the first match is replaced. +If pattern begins with `#', it must match at the beginning +of the expanded value of parameter. +If pattern begins with `%', it must match at the end +of the expanded value of parameter. +If string is null, matches of pattern are deleted +and the / following pattern may be omitted. +If parameter is `@' or `*', +the substitution operation is applied to each positional +parameter in turn, and the expansion is the resultant list. +If parameter +is an array variable subscripted with `@' or `*', +the substitution operation is applied to each member of the +array in turn, and the expansion is the resultant list. + +
    + +
    +

    + +Next: , +Previous: Shell Parameter Expansion, +Up: Shell Expansions + +
    + +

    3.5.4 Command Substitution

    + +

    +Command substitution allows the output of a command to replace +the command itself. +Command substitution occurs when a command is enclosed as follows: +

         $(command)
+
    +

    or +

         `command`
+
    +

    Bash performs the expansion by executing command and +replacing the command substitution with the standard output of the +command, with any trailing newlines deleted. +Embedded newlines are not deleted, but they may be removed during +word splitting. +The command substitution $(cat file) can be +replaced by the equivalent but faster $(< file). + +

    When the old-style backquote form of substitution is used, +backslash retains its literal meaning except when followed by +`$', ``', or `\'. +The first backquote not preceded by a backslash terminates the +command substitution. +When using the $(command) form, all characters between +the parentheses make up the command; none are treated specially. + +

    Command substitutions may be nested. To nest when using the backquoted +form, escape the inner backquotes with backslashes. + +

    If the substitution appears within double quotes, word splitting and +filename expansion are not performed on the results. + +

    +

    + +Next: , +Previous: Command Substitution, +Up: Shell Expansions + +
    + +

    3.5.5 Arithmetic Expansion

    + +

    +Arithmetic expansion allows the evaluation of an arithmetic expression +and the substitution of the result. The format for arithmetic expansion is: + +

         $(( expression ))
+
    +

    The expression is treated as if it were within double quotes, but +a double quote inside the parentheses is not treated specially. +All tokens in the expression undergo parameter expansion, command +substitution, and quote removal. +Arithmetic expansions may be nested. + +

    The evaluation is performed according to the rules listed below +(see Shell Arithmetic). +If the expression is invalid, Bash prints a message indicating +failure to the standard error and no substitution occurs. + +

    +

    + +Next: , +Previous: Arithmetic Expansion, +Up: Shell Expansions + +
    + +

    3.5.6 Process Substitution

    + +

    +Process substitution is supported on systems that support named +pipes (fifos) or the /dev/fd method of naming open files. +It takes the form of +

         <(list)
+
    +

    or +

         >(list)
+
    +

    The process list is run with its input or output connected to a +fifo or some file in /dev/fd. The name of this file is +passed as an argument to the current command as the result of the +expansion. If the >(list) form is used, writing to +the file will provide input for list. If the +<(list) form is used, the file passed as an +argument should be read to obtain the output of list. +Note that no space may appear between the < or > +and the left parenthesis, otherwise the construct would be interpreted +as a redirection. + +

    When available, process substitution is performed simultaneously with +parameter and variable expansion, command substitution, and arithmetic +expansion. + +

    +

    + +Next: , +Previous: Process Substitution, +Up: Shell Expansions + +
    + +

    3.5.7 Word Splitting

    + +

    +The shell scans the results of parameter expansion, command substitution, +and arithmetic expansion that did not occur within double quotes for +word splitting. + +

    The shell treats each character of $IFS as a delimiter, and splits +the results of the other expansions into words on these characters. +If IFS is unset, or its value is exactly <space><tab><newline>, +the default, then sequences of + <space>, <tab>, and <newline> +at the beginning and end of the results of the previous +expansions are ignored, and any sequence of IFS +characters not at the beginning or end serves to delimit words. +If IFS has a value other than the default, then sequences of +the whitespace characters space and tab +are ignored at the beginning and end of the +word, as long as the whitespace character is in the +value of IFS (an IFS whitespace character). +Any character in IFS that is not IFS +whitespace, along with any adjacent IFS +whitespace characters, delimits a field. A sequence of IFS +whitespace characters is also treated as a delimiter. +If the value of IFS is null, no word splitting occurs. + +

    Explicit null arguments ("" or '') are retained. +Unquoted implicit null arguments, resulting from the expansion of +parameters that have no values, are removed. +If a parameter with no value is expanded within double quotes, a +null argument results and is retained. + +

    Note that if no expansion occurs, no splitting +is performed. + +

    +

    + +Next: , +Previous: Word Splitting, +Up: Shell Expansions + +
    + +

    3.5.8 Filename Expansion

    + + + +After word splitting, unless the -f option has been set +(see The Set Builtin), Bash scans each word for the characters +`*', `?', and `['. +If one of these characters appears, then the word is +regarded as a pattern, +and replaced with an alphabetically sorted list of +file names matching the pattern. If no matching file names are found, +and the shell option nullglob is disabled, the word is left +unchanged. +If the nullglob option is set, and no matches are found, the word +is removed. +If the failglob shell option is set, and no matches are found, +an error message is printed and the command is not executed. +If the shell option nocaseglob is enabled, the match is performed +without regard to the case of alphabetic characters. + +

    When a pattern is used for filename generation, the character `.' +at the start of a filename or immediately following a slash +must be matched explicitly, unless the shell option dotglob is set. +When matching a file name, the slash character must always be +matched explicitly. +In other cases, the `.' character is not treated specially. + +

    See the description of shopt in The Shopt Builtin, +for a description of the nocaseglob, nullglob, +failglob, and dotglob options. + +

    The GLOBIGNORE +shell variable may be used to restrict the set of filenames matching a +pattern. If GLOBIGNORE +is set, each matching filename that also matches one of the patterns in +GLOBIGNORE is removed from the list of matches. The filenames +. and .. +are always ignored when GLOBIGNORE +is set and not null. +However, setting GLOBIGNORE to a non-null value has the effect of +enabling the dotglob +shell option, so all other filenames beginning with a +`.' will match. +To get the old behavior of ignoring filenames beginning with a +`.', make `.*' one of the patterns in GLOBIGNORE. +The dotglob option is disabled when GLOBIGNORE +is unset. + +

    +

    + +Up: Filename Expansion + +
    + +
    3.5.8.1 Pattern Matching
    + +

    +Any character that appears in a pattern, other than the special pattern +characters described below, matches itself. +The nul character may not occur in a pattern. +A backslash escapes the following character; the +escaping backslash is discarded when matching. +The special pattern characters must be quoted if they are to be matched +literally. + +

    The special pattern characters have the following meanings: +

    +
    *
    Matches any string, including the null string. +
    ?
    Matches any single character. +
    [...]
    Matches any one of the enclosed characters. A pair of characters +separated by a hyphen denotes a range expression; +any character that sorts between those two characters, inclusive, +using the current locale's collating sequence and character set, +is matched. If the first character following the +`[' is a `!' or a `^' +then any character not enclosed is matched. A `−' +may be matched by including it as the first or last character +in the set. A `]' may be matched by including it as the first +character in the set. +The sorting order of characters in range expressions is determined by +the current locale and the value of the LC_COLLATE shell variable, +if set. + +

    For example, in the default C locale, `[a-dx-z]' is equivalent to +`[abcdxyz]'. Many locales sort characters in dictionary order, and in +these locales `[a-dx-z]' is typically not equivalent to `[abcdxyz]'; +it might be equivalent to `[aBbCcDdxXyYz]', for example. To obtain +the traditional interpretation of ranges in bracket expressions, you can +force the use of the C locale by setting the LC_COLLATE or +LC_ALL environment variable to the value `C'. + +

    Within `[' and `]', character classes can be specified +using the syntax +[:class:], where class is one of the +following classes defined in the posix standard: + 

              alnum   alpha   ascii   blank   cntrl   digit   graph   lower
+          print   punct   space   upper   word    xdigit
+
    +

    A character class matches any character belonging to that class. +The word character class matches letters, digits, and the character +`_'. + +

    Within `[' and `]', an equivalence class can be +specified using the syntax [=c=], which +matches all characters with the same collation weight (as defined +by the current locale) as the character c. + +

    Within `[' and `]', the syntax [.symbol.] +matches the collating symbol symbol. +

    + +

    If the extglob shell option is enabled using the shopt +builtin, several extended pattern matching operators are recognized. +In the following description, a pattern-list is a list of one +or more patterns separated by a `|'. +Composite patterns may be formed using one or more of the following +sub-patterns: + +

    +
    ?(pattern-list)
    Matches zero or one occurrence of the given patterns. + +
    *(pattern-list)
    Matches zero or more occurrences of the given patterns. + +
    +(pattern-list)
    Matches one or more occurrences of the given patterns. + +
    @(pattern-list)
    Matches one of the given patterns. + +
    !(pattern-list)
    Matches anything except one of the given patterns. +
    + +
    +

    + +Previous: Filename Expansion, +Up: Shell Expansions + +
    + +

    3.5.9 Quote Removal

    + +

    After the preceding expansions, all unquoted occurrences of the +characters `\', `'', and `"' that did not +result from one of the above expansions are removed. + +

    +

    + +Next: , +Previous: Shell Expansions, +Up: Basic Shell Features + +
    + +

    3.6 Redirections

    + +

    +Before a command is executed, its input and output +may be redirected +using a special notation interpreted by the shell. +Redirection may also be used to open and close files for the +current shell execution environment. The following redirection +operators may precede or appear anywhere within a +simple command or may follow a command. +Redirections are processed in the order they appear, from +left to right. + +

    In the following descriptions, if the file descriptor number is +omitted, and the first character of the redirection operator is +`<', the redirection refers to the standard input (file +descriptor 0). If the first character of the redirection operator +is `>', the redirection refers to the standard output (file +descriptor 1). + +

    The word following the redirection operator in the following +descriptions, unless otherwise noted, is subjected to brace expansion, +tilde expansion, parameter expansion, command substitution, arithmetic +expansion, quote removal, filename expansion, and word splitting. +If it expands to more than one word, Bash reports an error. + +

    Note that the order of redirections is significant. For example, +the command +

         ls > dirlist 2>&1
+
    +

    directs both standard output (file descriptor 1) and standard error +(file descriptor 2) to the file dirlist, while the command +

         ls 2>&1 > dirlist
+
    +

    directs only the standard output to file dirlist, +because the standard error was duplicated as standard output +before the standard output was redirected to dirlist. + +

    Bash handles several filenames specially when they are used in +redirections, as described in the following table: + +

    +
    /dev/fd/fd
    If fd is a valid integer, file descriptor fd is duplicated. + +
    /dev/stdin
    File descriptor 0 is duplicated. + +
    /dev/stdout
    File descriptor 1 is duplicated. + +
    /dev/stderr
    File descriptor 2 is duplicated. + +
    /dev/tcp/host/port
    If host is a valid hostname or Internet address, and port +is an integer port number or service name, Bash attempts to open a TCP +connection to the corresponding socket. + +
    /dev/udp/host/port
    If host is a valid hostname or Internet address, and port +is an integer port number or service name, Bash attempts to open a UDP +connection to the corresponding socket. + +
    + +

    A failure to open or create a file causes the redirection to fail. + +

    Redirections using file descriptors greater than 9 should be used with +care, as they may conflict with file descriptors the shell uses +internally. + +

    3.6.1 Redirecting Input

    + +

    Redirection of input causes the file whose name results from +the expansion of word +to be opened for reading on file descriptor n, +or the standard input (file descriptor 0) if n +is not specified. + +

    The general format for redirecting input is: +

         [n]<word
+
    +

    3.6.2 Redirecting Output

    + +

    Redirection of output causes the file whose name results from +the expansion of word +to be opened for writing on file descriptor n, +or the standard output (file descriptor 1) if n +is not specified. If the file does not exist it is created; +if it does exist it is truncated to zero size. + +

    The general format for redirecting output is: +

         [n]>[|]word
+
    +

    If the redirection operator is `>', and the noclobber +option to the set builtin has been enabled, the redirection +will fail if the file whose name results from the expansion of +word exists and is a regular file. +If the redirection operator is `>|', or the redirection operator is +`>' and the noclobber option is not enabled, the redirection +is attempted even if the file named by word exists. + +

    3.6.3 Appending Redirected Output

    + +

    Redirection of output in this fashion +causes the file whose name results from +the expansion of word +to be opened for appending on file descriptor n, +or the standard output (file descriptor 1) if n +is not specified. If the file does not exist it is created. + +

    The general format for appending output is: +

         [n]>>word
+
    +

    3.6.4 Redirecting Standard Output and Standard Error

    + +

    Bash allows both the +standard output (file descriptor 1) and +the standard error output (file descriptor 2) +to be redirected to the file whose name is the +expansion of word with this construct. + +

    There are two formats for redirecting standard output and +standard error: +

         &>word
+
    +

    and +

         >&word
+
    +

    Of the two forms, the first is preferred. +This is semantically equivalent to +

         >word 2>&1
+
    +

    3.6.5 Here Documents

    + +

    This type of redirection instructs the shell to read input from the +current source until a line containing only word +(with no trailing blanks) is seen. All of +the lines read up to that point are then used as the standard +input for a command. + +

    The format of here-documents is: +

         <<[−]word
+             here-document
+     delimiter
+
    +

    No parameter expansion, command substitution, arithmetic expansion, +or filename expansion is performed on +word. If any characters in word are quoted, the +delimiter is the result of quote removal on word, +and the lines in the here-document are not expanded. +If word is unquoted, +all lines of the here-document are subjected to parameter expansion, +command substitution, and arithmetic expansion. In the latter +case, the character sequence \newline is ignored, and `\' +must be used to quote the characters +`\', `$', and ``'. + +

    If the redirection operator is `<<-', +then all leading tab characters are stripped from input lines and the +line containing delimiter. +This allows here-documents within shell scripts to be indented in a +natural fashion. + +

    3.6.6 Here Strings

    + +

    A variant of here documents, the format is: +

         <<< word
+
    +

    The word is expanded and supplied to the command on its standard +input. + +

    3.6.7 Duplicating File Descriptors

    + +

    The redirection operator +

         [n]<&word
+
    +

    is used to duplicate input file descriptors. +If word +expands to one or more digits, the file descriptor denoted by n +is made to be a copy of that file descriptor. +If the digits in word do not specify a file descriptor open for +input, a redirection error occurs. +If word +evaluates to `-', file descriptor n is closed. If +n is not specified, the standard input (file descriptor 0) is used. + +

    The operator +

         [n]>&word
+
    +

    is used similarly to duplicate output file descriptors. If +n is not specified, the standard output (file descriptor 1) is used. +If the digits in word do not specify a file descriptor open for +output, a redirection error occurs. +As a special case, if n is omitted, and word does not +expand to one or more digits, the standard output and standard +error are redirected as described previously. + +

    3.6.8 Moving File Descriptors

    + +

    The redirection operator +

         [n]<&digit-
+
    +

    moves the file descriptor digit to file descriptor n, +or the standard input (file descriptor 0) if n is not specified. +digit is closed after being duplicated to n. + +

    Similarly, the redirection operator +

         [n]>&digit-
+
    +

    moves the file descriptor digit to file descriptor n, +or the standard output (file descriptor 1) if n is not specified. + +

    3.6.9 Opening File Descriptors for Reading and Writing

    + +

    The redirection operator +

         [n]<>word
+
    +

    causes the file whose name is the expansion of word +to be opened for both reading and writing on file descriptor +n, or on file descriptor 0 if n +is not specified. If the file does not exist, it is created. + +

    +

    + +Next: , +Previous: Redirections, +Up: Basic Shell Features + +
    + +

    3.7 Executing Commands

    + + + +
    +

    + +Next: , +Up: Executing Commands + +
    + +

    3.7.1 Simple Command Expansion

    + +

    +When a simple command is executed, the shell performs the following +expansions, assignments, and redirections, from left to right. + +

      +
    1. The words that the parser has marked as variable assignments (those +preceding the command name) and redirections are saved for later +processing. + +
    2. The words that are not variable assignments or redirections are +expanded (see Shell Expansions). +If any words remain after expansion, the first word +is taken to be the name of the command and the remaining words are +the arguments. + +
    3. Redirections are performed as described above (see Redirections). + +
    4. The text after the `=' in each variable assignment undergoes tilde +expansion, parameter expansion, command substitution, arithmetic expansion, +and quote removal before being assigned to the variable. +
    + +

    If no command name results, the variable assignments affect the current +shell environment. Otherwise, the variables are added to the environment +of the executed command and do not affect the current shell environment. +If any of the assignments attempts to assign a value to a readonly variable, +an error occurs, and the command exits with a non-zero status. + +

    If no command name results, redirections are performed, but do not +affect the current shell environment. A redirection error causes the +command to exit with a non-zero status. + +

    If there is a command name left after expansion, execution proceeds as +described below. Otherwise, the command exits. If one of the expansions +contained a command substitution, the exit status of the command is +the exit status of the last command substitution performed. If there +were no command substitutions, the command exits with a status of zero. + +

    +

    + +Next: , +Previous: Simple Command Expansion, +Up: Executing Commands + +
    + +

    3.7.2 Command Search and Execution

    + +

    +After a command has been split into words, if it results in a +simple command and an optional list of arguments, the following +actions are taken. + +

      +
    1. If the command name contains no slashes, the shell attempts to +locate it. If there exists a shell function by that name, that +function is invoked as described in Shell Functions. + +
    2. If the name does not match a function, the shell searches for +it in the list of shell builtins. If a match is found, that +builtin is invoked. + +
    3. If the name is neither a shell function nor a builtin, +and contains no slashes, Bash searches each element of +$PATH for a directory containing an executable file +by that name. Bash uses a hash table to remember the full +pathnames of executable files to avoid multiple PATH searches +(see the description of hash in Bourne Shell Builtins). +A full search of the directories in $PATH +is performed only if the command is not found in the hash table. +If the search is unsuccessful, the shell prints an error +message and returns an exit status of 127. + +
    4. If the search is successful, or if the command name contains +one or more slashes, the shell executes the named program in +a separate execution environment. +Argument 0 is set to the name given, and the remaining arguments +to the command are set to the arguments supplied, if any. + +
    5. If this execution fails because the file is not in executable +format, and the file is not a directory, it is assumed to be a +shell script and the shell executes it as described in +Shell Scripts. + +
    6. If the command was not begun asynchronously, the shell waits for +the command to complete and collects its exit status. + +
    + +
    +

    + +Next: , +Previous: Command Search and Execution, +Up: Executing Commands + +
    + +

    3.7.3 Command Execution Environment

    + +

    +The shell has an execution environment, which consists of the +following: + +

      +
    • open files inherited by the shell at invocation, as modified by +redirections supplied to the exec builtin + +
    • the current working directory as set by cd, pushd, or +popd, or inherited by the shell at invocation + +
    • the file creation mode mask as set by umask or inherited from +the shell's parent + +
    • current traps set by trap + +
    • shell parameters that are set by variable assignment or with set +or inherited from the shell's parent in the environment + +
    • shell functions defined during execution or inherited from the shell's +parent in the environment + +
    • options enabled at invocation (either by default or with command-line +arguments) or by set + +
    • options enabled by shopt (see The Shopt Builtin) + +
    • shell aliases defined with alias (see Aliases) + +
    • various process ids, including those of background jobs +(see Lists), the value of $$, and the value of +$PPID + +
    + +

    When a simple command other than a builtin or shell function +is to be executed, it +is invoked in a separate execution environment that consists of +the following. Unless otherwise noted, the values are inherited +from the shell. + +

      +
    • the shell's open files, plus any modifications and additions specified +by redirections to the command + +
    • the current working directory + +
    • the file creation mode mask + +
    • shell variables and functions marked for export, along with variables +exported for the command, passed in the environment (see Environment) + +
    • traps caught by the shell are reset to the values inherited from the +shell's parent, and traps ignored by the shell are ignored + +
    + +

    A command invoked in this separate environment cannot affect the +shell's execution environment. + +

    Command substitution, commands grouped with parentheses, +and asynchronous commands are invoked in a +subshell environment that is a duplicate of the shell environment, +except that traps caught by the shell are reset to the values +that the shell inherited from its parent at invocation. Builtin +commands that are invoked as part of a pipeline are also executed +in a subshell environment. Changes made to the subshell environment +cannot affect the shell's execution environment. + +

    If a command is followed by a `&' and job control is not active, the +default standard input for the command is the empty file /dev/null. +Otherwise, the invoked command inherits the file descriptors of the calling +shell as modified by redirections. + +

    +

    + +Next: , +Previous: Command Execution Environment, +Up: Executing Commands + +
    + +

    3.7.4 Environment

    + +

    +When a program is invoked it is given an array of strings +called the environment. +This is a list of name-value pairs, of the form name=value. + +

    Bash provides several ways to manipulate the environment. +On invocation, the shell scans its own environment and +creates a parameter for each name found, automatically marking +it for export +to child processes. Executed commands inherit the environment. +The export and `declare -x' +commands allow parameters and functions to be added to and +deleted from the environment. If the value of a parameter +in the environment is modified, the new value becomes part +of the environment, replacing the old. The environment +inherited by any executed command consists of the shell's +initial environment, whose values may be modified in the shell, +less any pairs removed by the unset and `export -n' +commands, plus any additions via the export and +`declare -x' commands. + +

    The environment for any simple command +or function may be augmented temporarily by prefixing it with +parameter assignments, as described in Shell Parameters. +These assignment statements affect only the environment seen +by that command. + +

    If the -k option is set (see The Set Builtin), then all +parameter assignments are placed in the environment for a command, +not just those that precede the command name. + +

    When Bash invokes an external command, the variable `$_' +is set to the full path name of the command and passed to that +command in its environment. + +

    +

    + +Next: , +Previous: Environment, +Up: Executing Commands + +
    + +

    3.7.5 Exit Status

    + +

    +For the shell's purposes, a command which exits with a +zero exit status has succeeded. +A non-zero exit status indicates failure. +This seemingly counter-intuitive scheme is used so there +is one well-defined way to indicate success and a variety of +ways to indicate various failure modes. +When a command terminates on a fatal signal whose number is N, +Bash uses the value 128+N as the exit status. + +

    If a command is not found, the child process created to +execute it returns a status of 127. If a command is found +but is not executable, the return status is 126. + +

    If a command fails because of an error during expansion or redirection, +the exit status is greater than zero. + +

    The exit status is used by the Bash conditional commands +(see Conditional Constructs) and some of the list +constructs (see Lists). + +

    All of the Bash builtins return an exit status of zero if they succeed +and a non-zero status on failure, so they may be used by the +conditional and list constructs. +All builtins return an exit status of 2 to indicate incorrect usage. + +

    +

    + +Previous: Exit Status, +Up: Executing Commands + +
    + +

    3.7.6 Signals

    + +

    +When Bash is interactive, in the absence of any traps, it ignores +SIGTERM (so that `kill 0' does not kill an interactive shell), +and SIGINT +is caught and handled (so that the wait builtin is interruptible). +When Bash receives a SIGINT, it breaks out of any executing loops. +In all cases, Bash ignores SIGQUIT. +If job control is in effect (see Job Control), Bash +ignores SIGTTIN, SIGTTOU, and SIGTSTP. + +

    Non-builtin commands started by Bash have signal handlers set to the +values inherited by the shell from its parent. +When job control is not in effect, asynchronous commands +ignore SIGINT and SIGQUIT in addition to these inherited +handlers. +Commands run as a result of +command substitution ignore the keyboard-generated job control signals +SIGTTIN, SIGTTOU, and SIGTSTP. + +

    The shell exits by default upon receipt of a SIGHUP. +Before exiting, an interactive shell resends the SIGHUP to +all jobs, running or stopped. +Stopped jobs are sent SIGCONT to ensure that they receive +the SIGHUP. +To prevent the shell from sending the SIGHUP signal to a +particular job, it should be removed +from the jobs table with the disown +builtin (see Job Control Builtins) or marked +to not receive SIGHUP using disown -h. + +

    If the huponexit shell option has been set with shopt +(see The Shopt Builtin), Bash sends a SIGHUP to all jobs when +an interactive login shell exits. + +

    If Bash is waiting for a command to complete and receives a signal +for which a trap has been set, the trap will not be executed until +the command completes. +When Bash is waiting for an asynchronous +command via the wait builtin, the reception of a signal for +which a trap has been set will cause the wait builtin to return +immediately with an exit status greater than 128, immediately after +which the trap is executed. + +

    +

    + +Previous: Executing Commands, +Up: Basic Shell Features + +
    + +

    3.8 Shell Scripts

    + +

    +A shell script is a text file containing shell commands. When such +a file is used as the first non-option argument when invoking Bash, +and neither the -c nor -s option is supplied +(see Invoking Bash), +Bash reads and executes commands from the file, then exits. This +mode of operation creates a non-interactive shell. The shell first +searches for the file in the current directory, and looks in the +directories in $PATH if not found there. + +

    When Bash runs +a shell script, it sets the special parameter 0 to the name +of the file, rather than the name of the shell, and the positional +parameters are set to the remaining arguments, if any are given. +If no additional arguments are supplied, the positional parameters +are unset. + +

    A shell script may be made executable by using the chmod command +to turn on the execute bit. When Bash finds such a file while +searching the $PATH for a command, it spawns a subshell to +execute it. In other words, executing +

         filename arguments
+
    +

    is equivalent to executing +

         bash filename arguments
+
    +

    if filename is an executable shell script. +This subshell reinitializes itself, so that the effect is as if a +new shell had been invoked to interpret the script, with the +exception that the locations of commands remembered by the parent +(see the description of hash in Bourne Shell Builtins) +are retained by the child. + +

    Most versions of Unix make this a part of the operating system's command +execution mechanism. If the first line of a script begins with +the two characters `#!', the remainder of the line specifies +an interpreter for the program. +Thus, you can specify Bash, awk, Perl, or some other +interpreter and write the rest of the script file in that language. + +

    The arguments to the interpreter +consist of a single optional argument following the interpreter +name on the first line of the script file, followed by the name of +the script file, followed by the rest of the arguments. Bash +will perform this action on operating systems that do not handle it +themselves. Note that some older versions of Unix limit the interpreter +name and argument to a maximum of 32 characters. + +

    Bash scripts often begin with #! /bin/bash (assuming that +Bash has been installed in /bin), since this ensures that +Bash will be used to interpret the script, even if it is executed +under another shell. + +

    +

    + +Next: , +Previous: Basic Shell Features, +Up: Top + +
    + +

    4 Shell Builtin Commands

    + + + +

    Builtin commands are contained within the shell itself. +When the name of a builtin command is used as the first word of +a simple command (see Simple Commands), the shell executes +the command directly, without invoking another program. +Builtin commands are necessary to implement functionality impossible +or inconvenient to obtain with separate utilities. + +

    This section briefly describes the builtins which Bash inherits from +the Bourne Shell, as well as the builtin commands which are unique +to or have been extended in Bash. + +

    Several builtin commands are described in other chapters: builtin +commands which provide the Bash interface to the job control +facilities (see Job Control Builtins), the directory stack +(see Directory Stack Builtins), the command history +(see Bash History Builtins), and the programmable completion +facilities (see Programmable Completion Builtins). + +

    Many of the builtins have been extended by posix or Bash. + +

    Unless otherwise noted, each builtin command documented as accepting +options preceded by `-' accepts `--' +to signify the end of the options. +For example, the :, true, false, and test +builtins do not accept options. + +

    +

    + +Next: , +Up: Shell Builtin Commands + +
    + +

    4.1 Bourne Shell Builtins

    + +

    The following shell builtin commands are inherited from the Bourne Shell. +These commands are implemented as specified by the posix standard. + +

    +
    : (a colon)
    + 
              : [arguments]
+
    +

    Do nothing beyond expanding arguments and performing redirections. +The return status is zero. + +

    . (a period)
    + 
              . filename [arguments]
+
    +

    Read and execute commands from the filename argument in the +current shell context. If filename does not contain a slash, +the PATH variable is used to find filename. +When Bash is not in posix mode, the current directory is searched +if filename is not found in $PATH. +If any arguments are supplied, they become the positional +parameters when filename is executed. Otherwise the positional +parameters are unchanged. +The return status is the exit status of the last command executed, or +zero if no commands are executed. If filename is not found, or +cannot be read, the return status is non-zero. +This builtin is equivalent to source. + +

    break
    + 
              break [n]
+
    +

    Exit from a for, while, until, or select loop. +If n is supplied, the nth enclosing loop is exited. +n must be greater than or equal to 1. +The return status is zero unless n is not greater than or equal to 1. + +

    cd
    + 
              cd [-L|-P] [directory]
+
    +

    Change the current working directory to directory. +If directory is not given, the value of the HOME shell +variable is used. +If the shell variable CDPATH exists, it is used as a search path. +If directory begins with a slash, CDPATH is not used. + +

    The -P option means to not follow symbolic links; symbolic +links are followed by default or with the -L option. +If directory is `-', it is equivalent to $OLDPWD. + +

    If a non-empty directory name from CDPATH is used, or if +`-' is the first argument, and the directory change is +successful, the absolute pathname of the new working directory is +written to the standard output. + +

    The return status is zero if the directory is successfully changed, +non-zero otherwise. + +

    continue
    + 
              continue [n]
+
    +

    Resume the next iteration of an enclosing for, while, +until, or select loop. +If n is supplied, the execution of the nth enclosing loop +is resumed. +n must be greater than or equal to 1. +The return status is zero unless n is not greater than or equal to 1. + +

    eval
    + 
              eval [arguments]
+
    +

    The arguments are concatenated together into a single command, which is +then read and executed, and its exit status returned as the exit status +of eval. +If there are no arguments or only empty arguments, the return status is +zero. + +

    exec
    + 
              exec [-cl] [-a name] [command [arguments]]
+
    +

    If command +is supplied, it replaces the shell without creating a new process. +If the -l option is supplied, the shell places a dash at the +beginning of the zeroth argument passed to command. +This is what the login program does. +The -c option causes command to be executed with an empty +environment. +If -a is supplied, the shell passes name as the zeroth +argument to command. +If no command is specified, redirections may be used to affect +the current shell environment. If there are no redirection errors, the +return status is zero; otherwise the return status is non-zero. + +

    exit
    + 
              exit [n]
+
    +

    Exit the shell, returning a status of n to the shell's parent. +If n is omitted, the exit status is that of the last command executed. +Any trap on EXIT is executed before the shell terminates. + +

    export
    + 
              export [-fn] [-p] [name[=value]]
+
    +

    Mark each name to be passed to child processes +in the environment. If the -f option is supplied, the names +refer to shell functions; otherwise the names refer to shell variables. +The -n option means to no longer mark each name for export. +If no names are supplied, or if the -p option is given, a +list of exported names is displayed. +The -p option displays output in a form that may be reused as input. +If a variable name is followed by =value, the value of +the variable is set to value. + +

    The return status is zero unless an invalid option is supplied, one of +the names is not a valid shell variable name, or -f is supplied +with a name that is not a shell function. + +

    getopts
    + 
              getopts optstring name [args]
+
    +

    getopts is used by shell scripts to parse positional parameters. +optstring contains the option characters to be recognized; if a +character is followed by a colon, the option is expected to have an +argument, which should be separated from it by white space. +The colon (`:') and question mark (`?') may not be +used as option characters. +Each time it is invoked, getopts +places the next option in the shell variable name, initializing +name if it does not exist, +and the index of the next argument to be processed into the +variable OPTIND. +OPTIND is initialized to 1 each time the shell or a shell script +is invoked. +When an option requires an argument, +getopts places that argument into the variable OPTARG. +The shell does not reset OPTIND automatically; it must be manually +reset between multiple calls to getopts within the same shell +invocation if a new set of parameters is to be used. + +

    When the end of options is encountered, getopts exits with a +return value greater than zero. +OPTIND is set to the index of the first non-option argument, +and name is set to `?'. + +

    getopts +normally parses the positional parameters, but if more arguments are +given in args, getopts parses those instead. + +

    getopts can report errors in two ways. If the first character of +optstring is a colon, silent +error reporting is used. In normal operation diagnostic messages +are printed when invalid options or missing option arguments are +encountered. +If the variable OPTERR +is set to 0, no error messages will be displayed, even if the first +character of optstring is not a colon. + +

    If an invalid option is seen, +getopts places `?' into name and, if not silent, +prints an error message and unsets OPTARG. +If getopts is silent, the option character found is placed in +OPTARG and no diagnostic message is printed. + +

    If a required argument is not found, and getopts +is not silent, a question mark (`?') is placed in name, +OPTARG is unset, and a diagnostic message is printed. +If getopts is silent, then a colon (`:') is placed in +name and OPTARG is set to the option character found. + +

    hash
    + 
              hash [-r] [-p filename] [-dt] [name]
+
    +

    Remember the full pathnames of commands specified as name arguments, +so they need not be searched for on subsequent invocations. +The commands are found by searching through the directories listed in +$PATH. +The -p option inhibits the path search, and filename is +used as the location of name. +The -r option causes the shell to forget all remembered locations. +The -d option causes the shell to forget the remembered location +of each name. +If the -t option is supplied, the full pathname to which each +name corresponds is printed. If multiple name arguments are +supplied with -t the name is printed before the hashed +full pathname. +The -l option causes output to be displayed in a format +that may be reused as input. +If no arguments are given, or if only -l is supplied, +information about remembered commands is printed. +The return status is zero unless a name is not found or an invalid +option is supplied. + +

    pwd
    + 
              pwd [-LP]
+
    +

    Print the absolute pathname of the current working directory. +If the -P option is supplied, the pathname printed will not +contain symbolic links. +If the -L option is supplied, the pathname printed may contain +symbolic links. +The return status is zero unless an error is encountered while +determining the name of the current directory or an invalid option +is supplied. + +

    readonly
    + 
              readonly [-apf] [name[=value]] ...
+
    +

    Mark each name as readonly. +The values of these names may not be changed by subsequent assignment. +If the -f option is supplied, each name refers to a shell +function. +The -a option means each name refers to an array variable. +If no name arguments are given, or if the -p +option is supplied, a list of all readonly names is printed. +The -p option causes output to be displayed in a format that +may be reused as input. +If a variable name is followed by =value, the value of +the variable is set to value. +The return status is zero unless an invalid option is supplied, one of +the name arguments is not a valid shell variable or function name, +or the -f option is supplied with a name that is not a shell function. + +

    return
    + 
              return [n]
+
    +

    Cause a shell function to exit with the return value n. +If n is not supplied, the return value is the exit status of the +last command executed in the function. +This may also be used to terminate execution of a script being executed +with the . (or source) builtin, returning either n or +the exit status of the last command executed within the script as the exit +status of the script. +Any command associated with the RETURN trap is executed +before execution resumes after the function or script. +The return status is non-zero if return is used outside a function +and not during the execution of a script by . or source. + +

    shift
    + 
              shift [n]
+
    +

    Shift the positional parameters to the left by n. +The positional parameters from n+1 ... $# are +renamed to $1 ... $#-n. +Parameters represented by the numbers $# to $#-n+1 +are unset. +n must be a non-negative number less than or equal to $#. +If n is zero or greater than $#, the positional parameters +are not changed. +If n is not supplied, it is assumed to be 1. +The return status is zero unless n is greater than $# or +less than zero, non-zero otherwise. + +

    test
    [
    Evaluate a conditional expression expr. +Each operator and operand must be a separate argument. +Expressions are composed of the primaries described below in +Bash Conditional Expressions. +test does not accept any options, nor does it accept and ignore +an argument of -- as signifying the end of options. + +

    When the [ form is used, the last argument to the command must +be a ]. + +

    Expressions may be combined using the following operators, listed in +decreasing order of precedence. + +

    +
    ! expr
    True if expr is false. + +
    ( expr )
    Returns the value of expr. +This may be used to override the normal precedence of operators. + +
    expr1 -a expr2
    True if both expr1 and expr2 are true. + +
    expr1 -o expr2
    True if either expr1 or expr2 is true. +
    + +

    The test and [ builtins evaluate conditional +expressions using a set of rules based on the number of arguments. + +

    +
    0 arguments
    The expression is false. + +
    1 argument
    The expression is true if and only if the argument is not null. + +
    2 arguments
    If the first argument is `!', the expression is true if and +only if the second argument is null. +If the first argument is one of the unary conditional operators +(see Bash Conditional Expressions), the expression +is true if the unary test is true. +If the first argument is not a valid unary operator, the expression is +false. + +
    3 arguments
    If the second argument is one of the binary conditional +operators (see Bash Conditional Expressions), the +result of the expression is the result of the binary test using the +first and third arguments as operands. +If the first argument is `!', the value is the negation of +the two-argument test using the second and third arguments. +If the first argument is exactly `(' and the third argument is +exactly `)', the result is the one-argument test of the second +argument. +Otherwise, the expression is false. +The `-a' and `-o' operators are considered binary operators +in this case. + +
    4 arguments
    If the first argument is `!', the result is the negation of +the three-argument expression composed of the remaining arguments. +Otherwise, the expression is parsed and evaluated according to +precedence using the rules listed above. + +
    5 or more arguments
    The expression is parsed and evaluated according to precedence +using the rules listed above. +
    + +
    times
    + 
              times
+
    +

    Print out the user and system times used by the shell and its children. +The return status is zero. + +

    trap
    + 
              trap [-lp] [arg] [sigspec ...]
+
    +

    The commands in arg are to be read and executed when the +shell receives signal sigspec. If arg is absent (and +there is a single sigspec) or +equal to `-', each specified signal's disposition is reset +to the value it had when the shell was started. +If arg is the null string, then the signal specified by +each sigspec is ignored by the shell and commands it invokes. +If arg is not present and -p has been supplied, +the shell displays the trap commands associated with each sigspec. +If no arguments are supplied, or +only -p is given, trap prints the list of commands +associated with each signal number in a form that may be reused as +shell input. +The -l option causes the shell to print a list of signal names +and their corresponding numbers. +Each sigspec is either a signal name or a signal number. +Signal names are case insensitive and the SIG prefix is optional. +If a sigspec +is 0 or EXIT, arg is executed when the shell exits. +If a sigspec is DEBUG, the command arg is executed +before every simple command, for command, case command, +select command, every arithmetic for command, and before +the first command executes in a shell function. +Refer to the description of the extglob option to the +shopt builtin (see The Shopt Builtin) for details of its +effect on the DEBUG trap. +If a sigspec is ERR, the command arg +is executed whenever a simple command has a non-zero exit status, +subject to the following conditions. +The ERR trap is not executed if the failed command is part of the +command list immediately following an until or while keyword, +part of the test in an if statement, +part of a && or || list, or if the command's return +status is being inverted using !. +These are the same conditions obeyed by the errexit option. +If a sigspec is RETURN, the command arg is executed +each time a shell function or a script executed with the . or +source builtins finishes executing. + +

    Signals ignored upon entry to the shell cannot be trapped or reset. +Trapped signals that are not being ignored are reset to their original +values in a child process when it is created. + +

    The return status is zero unless a sigspec does not specify a +valid signal. + +

    umask
    + 
              umask [-p] [-S] [mode]
+
    +

    Set the shell process's file creation mask to mode. If +mode begins with a digit, it is interpreted as an octal number; +if not, it is interpreted as a symbolic mode mask similar +to that accepted by the chmod command. If mode is +omitted, the current value of the mask is printed. If the -S +option is supplied without a mode argument, the mask is printed +in a symbolic format. +If the -p option is supplied, and mode +is omitted, the output is in a form that may be reused as input. +The return status is zero if the mode is successfully changed or if +no mode argument is supplied, and non-zero otherwise. + +

    Note that when the mode is interpreted as an octal number, each number +of the umask is subtracted from 7. Thus, a umask of 022 +results in permissions of 755. + +

    unset
    + 
              unset [-fv] [name]
+
    +

    Each variable or function name is removed. +If no options are supplied, or the -v option is given, each +name refers to a shell variable. +If the -f option is given, the names refer to shell +functions, and the function definition is removed. +Readonly variables and functions may not be unset. +The return status is zero unless a name is readonly. +

    + +
    +

    + +Next: , +Previous: Bourne Shell Builtins, +Up: Shell Builtin Commands + +
    + +

    4.2 Bash Builtin Commands

    + +

    This section describes builtin commands which are unique to +or have been extended in Bash. +Some of these commands are specified in the posix standard. + +

    +
    alias
    + 
              alias [-p] [name[=value] ...]
+
    +

    Without arguments or with the -p option, alias prints +the list of aliases on the standard output in a form that allows +them to be reused as input. +If arguments are supplied, an alias is defined for each name +whose value is given. If no value is given, the name +and value of the alias is printed. +Aliases are described in Aliases. + +

    bind
    + 
              bind [-m keymap] [-lpsvPSV]
+          bind [-m keymap] [-q function] [-u function] [-r keyseq]
+          bind [-m keymap] -f filename
+          bind [-m keymap] -x keyseq:shell-command
+          bind [-m keymap] keyseq:function-name
+          bind readline-command
+
    +

    Display current Readline (see Command Line Editing) +key and function bindings, +bind a key sequence to a Readline function or macro, +or set a Readline variable. +Each non-option argument is a command as it would appear in a +Readline initialization file (see Readline Init File), +but each binding or command must be passed as a separate argument; e.g., +`"\C-x\C-r":re-read-init-file'. +Options, if supplied, have the following meanings: + +

    +
    -m keymap
    Use keymap as the keymap to be affected by +the subsequent bindings. Acceptable keymap +names are +emacs, +emacs-standard, +emacs-meta, +emacs-ctlx, +vi, +vi-move, +vi-command, and +vi-insert. +vi is equivalent to vi-command; +emacs is equivalent to emacs-standard. + +
    -l
    List the names of all Readline functions. + +
    -p
    Display Readline function names and bindings in such a way that they +can be used as input or in a Readline initialization file. + +
    -P
    List current Readline function names and bindings. + +
    -v
    Display Readline variable names and values in such a way that they +can be used as input or in a Readline initialization file. + +
    -V
    List current Readline variable names and values. + +
    -s
    Display Readline key sequences bound to macros and the strings they output +in such a way that they can be used as input or in a Readline +initialization file. + +
    -S
    Display Readline key sequences bound to macros and the strings they output. + +
    -f filename
    Read key bindings from filename. + +
    -q function
    Query about which keys invoke the named function. + +
    -u function
    Unbind all keys bound to the named function. + +
    -r keyseq
    Remove any current binding for keyseq. + +
    -x keyseq:shell-command
    Cause shell-command to be executed whenever keyseq is +entered. + +
    + +

    The return status is zero unless an invalid option is supplied or an +error occurs. + +

    builtin
    + 
              builtin [shell-builtin [args]]
+
    +

    Run a shell builtin, passing it args, and return its exit status. +This is useful when defining a shell function with the same +name as a shell builtin, retaining the functionality of the builtin within +the function. +The return status is non-zero if shell-builtin is not a shell +builtin command. + +

    caller
    + 
              caller [expr]
+
    +

    Returns the context of any active subroutine call (a shell function or +a script executed with the . or source builtins). + +

    Without expr, caller displays the line number and source +filename of the current subroutine call. +If a non-negative integer is supplied as expr, caller +displays the line number, subroutine name, and source file corresponding +to that position in the current execution call stack. This extra +information may be used, for example, to print a stack trace. The +current frame is frame 0. + +

    The return value is 0 unless the shell is not executing a subroutine +call or expr does not correspond to a valid position in the +call stack. + +

    command
    + 
              command [-pVv] command [arguments ...]
+
    +

    Runs command with arguments ignoring any shell function +named command. +Only shell builtin commands or commands found by searching the +PATH are executed. +If there is a shell function named ls, running `command ls' +within the function will execute the external command ls +instead of calling the function recursively. +The -p option means to use a default value for PATH +that is guaranteed to find all of the standard utilities. +The return status in this case is 127 if command cannot be +found or an error occurred, and the exit status of command +otherwise. + +

    If either the -V or -v option is supplied, a +description of command is printed. The -v option +causes a single word indicating the command or file name used to +invoke command to be displayed; the -V option produces +a more verbose description. In this case, the return status is +zero if command is found, and non-zero if not. + +

    declare
    + 
              declare [-afFirtx] [-p] [name[=value] ...]
+
    +

    Declare variables and give them attributes. If no names +are given, then display the values of variables instead. + +

    The -p option will display the attributes and values of each +name. +When -p is used, additional options are ignored. +The -F option inhibits the display of function definitions; +only the function name and attributes are printed. +If the extdebug shell option is enabled using shopt +(see The Shopt Builtin), the source file name and line number where +the function is defined are displayed as well. +-F implies -f. +The following options can be used to restrict output to variables with +the specified attributes or to give variables attributes: + +

    +
    -a
    Each name is an array variable (see Arrays). + +
    -f
    Use function names only. + +
    -i
    The variable is to be treated as +an integer; arithmetic evaluation (see Shell Arithmetic) is +performed when the variable is assigned a value. + +
    -r
    Make names readonly. These names cannot then be assigned values +by subsequent assignment statements or unset. + +
    -t
    Give each name the trace attribute. +Traced functions inherit the DEBUG and RETURN traps from +the calling shell. +The trace attribute has no special meaning for variables. + +
    -x
    Mark each name for export to subsequent commands via +the environment. +
    + +

    Using `+' instead of `-' turns off the attribute instead, +with the exceptions that `+a' +may not be used to destroy an array variable and `+r' will not +remove the readonly attribute. +When used in a function, declare makes each name local, +as with the local command. If a variable name is followed by +=value, the value of the variable is set to value. + +

    The return status is zero unless an invalid option is encountered, +an attempt is made to define a function using `-f foo=bar', +an attempt is made to assign a value to a readonly variable, +an attempt is made to assign a value to an array variable without +using the compound assignment syntax (see Arrays), +one of the names is not a valid shell variable name, +an attempt is made to turn off readonly status for a readonly variable, +an attempt is made to turn off array status for an array variable, +or an attempt is made to display a non-existent function with -f. + +

    echo
    + 
              echo [-neE] [arg ...]
+
    +

    Output the args, separated by spaces, terminated with a +newline. +The return status is always 0. +If -n is specified, the trailing newline is suppressed. +If the -e option is given, interpretation of the following +backslash-escaped characters is enabled. +The -E option disables the interpretation of these escape characters, +even on systems where they are interpreted by default. +The xpg_echo shell option may be used to +dynamically determine whether or not echo expands these +escape characters by default. +echo does not interpret -- to mean the end of options. + +

    echo interprets the following escape sequences: +

    +
    \a
    alert (bell) +
    \b
    backspace +
    \c
    suppress trailing newline +
    \e
    escape +
    \f
    form feed +
    \n
    new line +
    \r
    carriage return +
    \t
    horizontal tab +
    \v
    vertical tab +
    \\
    backslash +
    \0nnn
    the eight-bit character whose value is the octal value nnn +(zero to three octal digits) +
    \xHH
    the eight-bit character whose value is the hexadecimal value HH +(one or two hex digits) +
    + +
    enable
    + 
              enable [-a] [-dnps] [-f filename] [name ...]
+
    +

    Enable and disable builtin shell commands. +Disabling a builtin allows a disk command which has the same name +as a shell builtin to be executed without specifying a full pathname, +even though the shell normally searches for builtins before disk commands. +If -n is used, the names become disabled. Otherwise +names are enabled. For example, to use the test binary +found via $PATH instead of the shell builtin version, type +`enable -n test'. + +

    If the -p option is supplied, or no name arguments appear, +a list of shell builtins is printed. With no other arguments, the list +consists of all enabled shell builtins. +The -a option means to list +each builtin with an indication of whether or not it is enabled. + +

    The -f option means to load the new builtin command name +from shared object filename, on systems that support dynamic loading. +The -d option will delete a builtin loaded with -f. + +

    If there are no options, a list of the shell builtins is displayed. +The -s option restricts enable to the posix special +builtins. If -s is used with -f, the new builtin becomes +a special builtin (see Special Builtins). + +

    The return status is zero unless a name is not a shell builtin +or there is an error loading a new builtin from a shared object. + +

    help
    + 
              help [-s] [pattern]
+
    +

    Display helpful information about builtin commands. +If pattern is specified, help gives detailed help +on all commands matching pattern, otherwise a list of +the builtins is printed. +The -s option restricts the information displayed to a short +usage synopsis. +The return status is zero unless no command matches pattern. + +

    let
    + 
              let expression [expression]
+
    +

    The let builtin allows arithmetic to be performed on shell +variables. Each expression is evaluated according to the +rules given below in Shell Arithmetic. If the +last expression evaluates to 0, let returns 1; +otherwise 0 is returned. + +

    local
    + 
              local [option] name[=value] ...
+
    +

    For each argument, a local variable named name is created, +and assigned value. +The option can be any of the options accepted by declare. +local can only be used within a function; it makes the variable +name have a visible scope restricted to that function and its +children. The return status is zero unless local is used outside +a function, an invalid name is supplied, or name is a +readonly variable. + +

    logout
    + 
              logout [n]
+
    +

    Exit a login shell, returning a status of n to the shell's +parent. + +

    printf
    + 
              printf [-v var] format [arguments]
+
    +

    Write the formatted arguments to the standard output under the +control of the format. +The format is a character string which contains three types of objects: +plain characters, which are simply copied to standard output, character +escape sequences, which are converted and copied to the standard output, and +format specifications, each of which causes printing of the next successive +argument. +In addition to the standard printf(1) formats, `%b' causes +printf to expand backslash escape sequences in the corresponding +argument, +(except that `\c' terminates output, backslashes in +`\'', `\"', and `\?' are not removed, and octal escapes +beginning with `\0' may contain up to four digits), +and `%q' causes printf to output the +corresponding argument in a format that can be reused as shell input. + +

    The -v option causes the output to be assigned to the variable +var rather than being printed to the standard output. + +

    The format is reused as necessary to consume all of the arguments. +If the format requires more arguments than are supplied, the +extra format specifications behave as if a zero value or null string, as +appropriate, had been supplied. The return value is zero on success, +non-zero on failure. + +

    read
    + 
              read [-ers] [-a aname] [-d delim] [-n nchars] [-p prompt] [-t timeout] [-u fd] [name ...]
+
    +

    One line is read from the standard input, or from the file descriptor +fd supplied as an argument to the -u option, and the first word +is assigned to the first name, the second word to the second name, +and so on, with leftover words and their intervening separators assigned +to the last name. +If there are fewer words read from the input stream than names, +the remaining names are assigned empty values. +The characters in the value of the IFS variable +are used to split the line into words. +The backslash character `\' may be used to remove any special +meaning for the next character read and for line continuation. +If no names are supplied, the line read is assigned to the +variable REPLY. +The return code is zero, unless end-of-file is encountered, read +times out, or an invalid file descriptor is supplied as the argument to +-u. +Options, if supplied, have the following meanings: + +

    +
    -a aname
    The words are assigned to sequential indices of the array variable +aname, starting at 0. +All elements are removed from aname before the assignment. +Other name arguments are ignored. + +
    -d delim
    The first character of delim is used to terminate the input line, +rather than newline. + +
    -e
    Readline (see Command Line Editing) is used to obtain the line. + +
    -n nchars
    read returns after reading nchars characters rather than +waiting for a complete line of input. + +
    -p prompt
    Display prompt, without a trailing newline, before attempting +to read any input. +The prompt is displayed only if input is coming from a terminal. + +
    -r
    If this option is given, backslash does not act as an escape character. +The backslash is considered to be part of the line. +In particular, a backslash-newline pair may not be used as a line +continuation. + +
    -s
    Silent mode. If input is coming from a terminal, characters are +not echoed. + +
    -t timeout
    Cause read to time out and return failure if a complete line of +input is not read within timeout seconds. +This option has no effect if read is not reading input from the +terminal or a pipe. + +
    -u fd
    Read input from file descriptor fd. + +
    + +
    source
    + 
              source filename
+
    +

    A synonym for . (see Bourne Shell Builtins). + +

    type
    + 
              type [-afptP] [name ...]
+
    +

    For each name, indicate how it would be interpreted if used as a +command name. + +

    If the -t option is used, type prints a single word +which is one of `alias', `function', `builtin', +`file' or `keyword', +if name is an alias, shell function, shell builtin, +disk file, or shell reserved word, respectively. +If the name is not found, then nothing is printed, and +type returns a failure status. + +

    If the -p option is used, type either returns the name +of the disk file that would be executed, or nothing if -t +would not return `file'. + +

    The -P option forces a path search for each name, even if +-t would not return `file'. + +

    If a command is hashed, -p and -P print the hashed value, +not necessarily the file that appears first in $PATH. + +

    If the -a option is used, type returns all of the places +that contain an executable named file. +This includes aliases and functions, if and only if the -p option +is not also used. + +

    If the -f option is used, type does not attempt to find +shell functions, as with the command builtin. + +

    The return status is zero if any of the names are found, non-zero +if none are found. + +

    typeset
    + 
              typeset [-afFrxi] [-p] [name[=value] ...]
+
    +

    The typeset command is supplied for compatibility with the Korn +shell; however, it has been deprecated in favor of the declare +builtin command. + +

    ulimit
    + 
              ulimit [-acdefilmnpqrstuvxSH] [limit]
+
    +

    ulimit provides control over the resources available to processes +started by the shell, on systems that allow such control. If an +option is given, it is interpreted as follows: +

    +
    -S
    Change and report the soft limit associated with a resource. + +
    -H
    Change and report the hard limit associated with a resource. + +
    -a
    All current limits are reported. + +
    -c
    The maximum size of core files created. + +
    -d
    The maximum size of a process's data segment. + +
    -e
    The maximum scheduling priority ("nice"). + +
    -f
    The maximum size of files written by the shell and its children. + +
    -i
    The maximum number of pending signals. + +
    -l
    The maximum size that may be locked into memory. + +
    -m
    The maximum resident set size. + +
    -n
    The maximum number of open file descriptors. + +
    -p
    The pipe buffer size. + +
    -q
    The maximum number of bytes in POSIX message queues. + +
    -r
    The maximum real-time scheduling priority. + +
    -s
    The maximum stack size. + +
    -t
    The maximum amount of cpu time in seconds. + +
    -u
    The maximum number of processes available to a single user. + +
    -v
    The maximum amount of virtual memory available to the process. + +
    -x
    The maximum number of file locks. + +
    + +

    If limit is given, it is the new value of the specified resource; +the special limit values hard, soft, and +unlimited stand for the current hard limit, the current soft limit, +and no limit, respectively. +Otherwise, the current value of the soft limit for the specified resource +is printed, unless the -H option is supplied. +When setting new limits, if neither -H nor -S is supplied, +both the hard and soft limits are set. +If no option is given, then -f is assumed. Values are in 1024-byte +increments, except for -t, which is in seconds, -p, +which is in units of 512-byte blocks, and -n and -u, which +are unscaled values. + +

    The return status is zero unless an invalid option or argument is supplied, +or an error occurs while setting a new limit. + +

    unalias
    + 
              unalias [-a] [name ... ]
+
    +

    Remove each name from the list of aliases. If -a is +supplied, all aliases are removed. +Aliases are described in Aliases. + +

    + +
    +

    + +Next: , +Previous: Bash Builtins, +Up: Shell Builtin Commands + +
    + +

    4.3 Modifying Shell Behavior

    + + + +
    +

    + +Next: , +Up: Modifying Shell Behavior + +
    + +

    4.3.1 The Set Builtin

    + +

    This builtin is so complicated that it deserves its own section. set +allows you to change the values of shell options and set the positional +parameters, or to display the names and values of shell variables. + +

    +
    set
    + 
              set [--abefhkmnptuvxBCEHPT] [-o option] [argument ...]
+          set [+abefhkmnptuvxBCEHPT] [+o option] [argument ...]
+
    +

    If no options or arguments are supplied, set displays the names +and values of all shell variables and functions, sorted according to the +current locale, in a format that may be reused as input +for setting or resetting the currently-set variables. +Read-only variables cannot be reset. +In posix mode, only shell variables are listed. + +

    When options are supplied, they set or unset shell attributes. +Options, if specified, have the following meanings: + +

    +
    -a
    Mark variables and function which are modified or created for export +to the environment of subsequent commands. + +
    -b
    Cause the status of terminated background jobs to be reported +immediately, rather than before printing the next primary prompt. + +
    -e
    Exit immediately if a simple command (see Simple Commands) exits +with a non-zero status, unless the command that fails is part of the +command list immediately following a while or until keyword, +part of the test in an if statement, +part of a && or || list, +any command in a pipeline but the last, +or if the command's return status is being inverted using !. +A trap on ERR, if set, is executed before the shell exits. + +
    -f
    Disable file name generation (globbing). + +
    -h
    Locate and remember (hash) commands as they are looked up for execution. +This option is enabled by default. + +
    -k
    All arguments in the form of assignment statements are placed +in the environment for a command, not just those that precede +the command name. + +
    -m
    Job control is enabled (see Job Control). + +
    -n
    Read commands but do not execute them; this may be used to check a +script for syntax errors. +This option is ignored by interactive shells. + +
    -o option-name
    +Set the option corresponding to option-name: + +
    +
    allexport
    Same as -a. + +
    braceexpand
    Same as -B. + +
    emacs
    Use an emacs-style line editing interface (see Command Line Editing). + +
    errexit
    Same as -e. + +
    errtrace
    Same as -E. + +
    functrace
    Same as -T. + +
    hashall
    Same as -h. + +
    histexpand
    Same as -H. + +
    history
    Enable command history, as described in Bash History Facilities. +This option is on by default in interactive shells. + +
    ignoreeof
    An interactive shell will not exit upon reading EOF. + +
    keyword
    Same as -k. + +
    monitor
    Same as -m. + +
    noclobber
    Same as -C. + +
    noexec
    Same as -n. + +
    noglob
    Same as -f. + +
    nolog
    Currently ignored. + +
    notify
    Same as -b. + +
    nounset
    Same as -u. + +
    onecmd
    Same as -t. + +
    physical
    Same as -P. + +
    pipefail
    If set, the return value of a pipeline is the value of the last +(rightmost) command to exit with a non-zero status, or zero if all +commands in the pipeline exit successfully. +This option is disabled by default. + +
    posix
    Change the behavior of Bash where the default operation differs +from the posix standard to match the standard +(see Bash POSIX Mode). +This is intended to make Bash behave as a strict superset of that +standard. + +
    privileged
    Same as -p. + +
    verbose
    Same as -v. + +
    vi
    Use a vi-style line editing interface. + +
    xtrace
    Same as -x. +
    + +
    -p
    Turn on privileged mode. +In this mode, the $BASH_ENV and $ENV files are not +processed, shell functions are not inherited from the environment, +and the SHELLOPTS variable, if it appears in the environment, +is ignored. +If the shell is started with the effective user (group) id not equal to the +real user (group) id, and the -p option is not supplied, these actions +are taken and the effective user id is set to the real user id. +If the -p option is supplied at startup, the effective user id is +not reset. +Turning this option off causes the effective user +and group ids to be set to the real user and group ids. + +
    -t
    Exit after reading and executing one command. + +
    -u
    Treat unset variables as an error when performing parameter expansion. +An error message will be written to the standard error, and a non-interactive +shell will exit. + +
    -v
    Print shell input lines as they are read. + +
    -x
    Print a trace of simple commands, for commands, case +commands, select commands, and arithmetic for commands +and their arguments or associated word lists after they are +expanded and before they are executed. The value of the PS4 +variable is expanded and the resultant value is printed before +the command and its expanded arguments. + +
    -B
    The shell will perform brace expansion (see Brace Expansion). +This option is on by default. + +
    -C
    Prevent output redirection using `>', `>&', and `<>' +from overwriting existing files. + +
    -E
    If set, any trap on ERR is inherited by shell functions, command +substitutions, and commands executed in a subshell environment. +The ERR trap is normally not inherited in such cases. + +
    -H
    Enable `!' style history substitution (see History Interaction). +This option is on by default for interactive shells. + +
    -P
    If set, do not follow symbolic links when performing commands such as +cd which change the current directory. The physical directory +is used instead. By default, Bash follows +the logical chain of directories when performing commands +which change the current directory. + +

    For example, if /usr/sys is a symbolic link to /usr/local/sys +then: + 

                   $ cd /usr/sys; echo $PWD
+               /usr/sys
+               $ cd ..; pwd
+               /usr
+
    +

    If set -P is on, then: + 

                   $ cd /usr/sys; echo $PWD
+               /usr/local/sys
+               $ cd ..; pwd
+               /usr/local
+
    +
    -T
    If set, any trap on DEBUG and RETURN are inherited by +shell functions, command substitutions, and commands executed +in a subshell environment. +The DEBUG and RETURN traps are normally not inherited +in such cases. + +
    --
    If no arguments follow this option, then the positional parameters are +unset. Otherwise, the positional parameters are set to the +arguments, even if some of them begin with a `-'. + +
    -
    Signal the end of options, cause all remaining arguments +to be assigned to the positional parameters. The -x +and -v options are turned off. +If there are no arguments, the positional parameters remain unchanged. +
    + +

    Using `+' rather than `-' causes these options to be +turned off. The options can also be used upon invocation of the +shell. The current set of options may be found in $-. + +

    The remaining N arguments are positional parameters and are +assigned, in order, to $1, $2, ... $N. +The special parameter # is set to N. + +

    The return status is always zero unless an invalid option is supplied. +

    + +
    +

    + +Previous: The Set Builtin, +Up: Modifying Shell Behavior + +
    + +

    4.3.2 The Shopt Builtin

    + +

    This builtin allows you to change additional shell optional behavior. + +

    +
    shopt
    + 
              shopt [-pqsu] [-o] [optname ...]
+
    +

    Toggle the values of variables controlling optional shell behavior. +With no options, or with the -p option, a list of all settable +options is displayed, with an indication of whether or not each is set. +The -p option causes output to be displayed in a form that +may be reused as input. +Other options have the following meanings: + +

    +
    -s
    Enable (set) each optname. + +
    -u
    Disable (unset) each optname. + +
    -q
    Suppresses normal output; the return status +indicates whether the optname is set or unset. +If multiple optname arguments are given with -q, +the return status is zero if all optnames are enabled; +non-zero otherwise. + +
    -o
    Restricts the values of +optname to be those defined for the -o option to the +set builtin (see The Set Builtin). +
    + +

    If either -s or -u +is used with no optname arguments, the display is limited to +those options which are set or unset, respectively. + +

    Unless otherwise noted, the shopt options are disabled (off) +by default. + +

    The return status when listing options is zero if all optnames +are enabled, non-zero otherwise. When setting or unsetting options, +the return status is zero unless an optname is not a valid shell +option. + +

    The list of shopt options is: +

    +
    autocd
    If set, a command name that is the name of a directory is executed as if +it were the argument to the cd command. +This option is only used by interactive shells. + +
    cdable_vars
    If this is set, an argument to the cd builtin command that +is not a directory is assumed to be the name of a variable whose +value is the directory to change to. + +
    cdspell
    If set, minor errors in the spelling of a directory component in a +cd command will be corrected. +The errors checked for are transposed characters, +a missing character, and a character too many. +If a correction is found, the corrected path is printed, +and the command proceeds. +This option is only used by interactive shells. + +
    checkhash
    If this is set, Bash checks that a command found in the hash +table exists before trying to execute it. If a hashed command no +longer exists, a normal path search is performed. + +
    checkjobs
    If set, Bash lists the status of any stopped and running jobs before +exiting an interactive shell. If any jobs are running, this causes +the exit to be deferred until a second exit is attempted without an +intervening command (see Job Control). +The shell always postpones exiting if any jobs are stopped. + +
    checkwinsize
    If set, Bash checks the window size after each command +and, if necessary, updates the values of +LINES and COLUMNS. + +
    cmdhist
    If set, Bash +attempts to save all lines of a multiple-line +command in the same history entry. This allows +easy re-editing of multi-line commands. + +
    dotglob
    If set, Bash includes filenames beginning with a `.' in +the results of filename expansion. + +
    execfail
    If this is set, a non-interactive shell will not exit if +it cannot execute the file specified as an argument to the exec +builtin command. An interactive shell does not exit if exec +fails. + +
    expand_aliases
    If set, aliases are expanded as described below under Aliases, +Aliases. +This option is enabled by default for interactive shells. + +
    extdebug
    If set, behavior intended for use by debuggers is enabled: + +
      +
    1. The -F option to the declare builtin (see Bash Builtins) +displays the source file name and line number corresponding to each function +name supplied as an argument. + +
    2. If the command run by the DEBUG trap returns a non-zero value, the +next command is skipped and not executed. + +
    3. If the command run by the DEBUG trap returns a value of 2, and the +shell is executing in a subroutine (a shell function or a shell script +executed by the . or source builtins), a call to +return is simulated. + +
    4. BASH_ARGC and BASH_ARGV are updated as described in their +descriptions (see Bash Variables). + +
    5. Function tracing is enabled: command substitution, shell functions, and +subshells invoked with ( command ) inherit the +DEBUG and RETURN traps. + +
    6. Error tracing is enabled: command substitution, shell functions, and +subshells invoked with ( command ) inherit the +ERROR trap. +
    + +
    extglob
    If set, the extended pattern matching features described above +(see Pattern Matching) are enabled. + +
    extquote
    If set, $'string' and $"string" quoting is +performed within ${parameter} expansions +enclosed in double quotes. This option is enabled by default. + +
    failglob
    If set, patterns which fail to match filenames during pathname expansion +result in an expansion error. + +
    force_fignore
    If set, the suffixes specified by the FIGNORE shell variable +cause words to be ignored when performing word completion even if +the ignored words are the only possible completions. +See Bash Variables, for a description of FIGNORE. +This option is enabled by default. + +
    gnu_errfmt
    If set, shell error messages are written in the standard gnu error +message format. + +
    histappend
    If set, the history list is appended to the file named by the value +of the HISTFILE +variable when the shell exits, rather than overwriting the file. + +
    histreedit
    If set, and Readline +is being used, a user is given the opportunity to re-edit a +failed history substitution. + +
    histverify
    If set, and Readline +is being used, the results of history substitution are not immediately +passed to the shell parser. Instead, the resulting line is loaded into +the Readline editing buffer, allowing further modification. + +
    hostcomplete
    If set, and Readline is being used, Bash will attempt to perform +hostname completion when a word containing a `@' is being +completed (see Commands For Completion). This option is enabled +by default. + +
    huponexit
    If set, Bash will send SIGHUP to all jobs when an interactive +login shell exits (see Signals). + +
    interactive_comments
    Allow a word beginning with `#' +to cause that word and all remaining characters on that +line to be ignored in an interactive shell. +This option is enabled by default. + +
    lithist
    If enabled, and the cmdhist +option is enabled, multi-line commands are saved to the history with +embedded newlines rather than using semicolon separators where possible. + +
    login_shell
    The shell sets this option if it is started as a login shell +(see Invoking Bash). +The value may not be changed. + +
    mailwarn
    If set, and a file that Bash is checking for mail has been +accessed since the last time it was checked, the message +"The mail in mailfile has been read" is displayed. + +
    no_empty_cmd_completion
    If set, and Readline is being used, Bash will not attempt to search +the PATH for possible completions when completion is attempted +on an empty line. + +
    nocaseglob
    If set, Bash matches filenames in a case-insensitive fashion when +performing filename expansion. + +
    nocasematch
    If set, Bash matches patterns in a case-insensitive fashion when +performing matching while executing case or [[ +conditional commands. + +
    nullglob
    If set, Bash allows filename patterns which match no +files to expand to a null string, rather than themselves. + +
    progcomp
    If set, the programmable completion facilities +(see Programmable Completion) are enabled. +This option is enabled by default. + +
    promptvars
    If set, prompt strings undergo +parameter expansion, command substitution, arithmetic +expansion, and quote removal after being expanded +as described below (see Printing a Prompt). +This option is enabled by default. + +
    restricted_shell
    The shell sets this option if it is started in restricted mode +(see The Restricted Shell). +The value may not be changed. +This is not reset when the startup files are executed, allowing +the startup files to discover whether or not a shell is restricted. + +
    shift_verbose
    If this is set, the shift +builtin prints an error message when the shift count exceeds the +number of positional parameters. + +
    sourcepath
    If set, the source builtin uses the value of PATH +to find the directory containing the file supplied as an argument. +This option is enabled by default. + +
    xpg_echo
    If set, the echo builtin expands backslash-escape sequences +by default. + +
    + +

    The return status when listing options is zero if all optnames +are enabled, non-zero otherwise. +When setting or unsetting options, the return status is zero unless an +optname is not a valid shell option. + +

    + +
    +

    + +Previous: Modifying Shell Behavior, +Up: Shell Builtin Commands + +
    + +

    4.4 Special Builtins

    + +

    +For historical reasons, the posix standard has classified +several builtin commands as special. +When Bash is executing in posix mode, the special builtins +differ from other builtin commands in three respects: + +

      +
    1. Special builtins are found before shell functions during command lookup. + +
    2. If a special builtin returns an error status, a non-interactive shell exits. + +
    3. Assignment statements preceding the command stay in effect in the shell +environment after the command completes. +
    + +

    When Bash is not executing in posix mode, these builtins behave no +differently than the rest of the Bash builtin commands. +The Bash posix mode is described in Bash POSIX Mode. + +

    These are the posix special builtins: +

         break : . continue eval exec exit export readonly return set
+     shift trap unset
+
    +
    +

    + +Next: , +Previous: Shell Builtin Commands, +Up: Top + +
    + +

    5 Shell Variables

    + + + +

    This chapter describes the shell variables that Bash uses. +Bash automatically assigns default values to a number of variables. + +

    +

    + +Next: , +Up: Shell Variables + +
    + +

    5.1 Bourne Shell Variables

    + +

    Bash uses certain shell variables in the same way as the Bourne shell. +In some cases, Bash assigns a default value to the variable. + +

    +
    CDPATH
    A colon-separated list of directories used as a search path for +the cd builtin command. + +
    HOME
    The current user's home directory; the default for the cd builtin +command. +The value of this variable is also used by tilde expansion +(see Tilde Expansion). + +
    IFS
    A list of characters that separate fields; used when the shell splits +words as part of expansion. + +
    MAIL
    If this parameter is set to a filename and the MAILPATH variable +is not set, Bash informs the user of the arrival of mail in +the specified file. + +
    MAILPATH
    A colon-separated list of filenames which the shell periodically checks +for new mail. +Each list entry can specify the message that is printed when new mail +arrives in the mail file by separating the file name from the message with +a `?'. +When used in the text of the message, $_ expands to the name of +the current mail file. + +
    OPTARG
    The value of the last option argument processed by the getopts builtin. + +
    OPTIND
    The index of the last option argument processed by the getopts builtin. + +
    PATH
    A colon-separated list of directories in which the shell looks for +commands. +A zero-length (null) directory name in the value of PATH indicates the +current directory. +A null directory name may appear as two adjacent colons, or as an initial +or trailing colon. + +
    PS1
    The primary prompt string. The default value is `\s-\v\$ '. +See Printing a Prompt, for the complete list of escape +sequences that are expanded before PS1 is displayed. + +
    PS2
    The secondary prompt string. The default value is `> '. + +
    + +
    +

    + +Previous: Bourne Shell Variables, +Up: Shell Variables + +
    + +

    5.2 Bash Variables

    + +

    These variables are set or used by Bash, but other shells +do not normally treat them specially. + +

    A few variables used by Bash are described in different chapters: +variables for controlling the job control facilities +(see Job Control Variables). + +

    +
    BASH
    The full pathname used to execute the current instance of Bash. + +
    BASHPID
    Expands to the process id of the current Bash process. +This differs from $$ under certain circumstances, such as subshells +that do not require Bash to be re-initialized. + +
    BASH_ARGC
    An array variable whose values are the number of parameters in each +frame of the current bash execution call stack. The number of +parameters to the current subroutine (shell function or script executed +with . or source) is at the top of the stack. When a +subroutine is executed, the number of parameters passed is pushed onto +BASH_ARGC. +The shell sets BASH_ARGC only when in extended debugging mode +(see The Shopt Builtin +for a description of the extdebug option to the shopt +builtin). + +
    BASH_ARGV
    An array variable containing all of the parameters in the current bash +execution call stack. The final parameter of the last subroutine call +is at the top of the stack; the first parameter of the initial call is +at the bottom. When a subroutine is executed, the parameters supplied +are pushed onto BASH_ARGV. +The shell sets BASH_ARGV only when in extended debugging mode +(see The Shopt Builtin +for a description of the extdebug option to the shopt +builtin). + +
    BASH_COMMAND
    The command currently being executed or about to be executed, unless the +shell is executing a command as the result of a trap, +in which case it is the command executing at the time of the trap. + +
    BASH_ENV
    If this variable is set when Bash is invoked to execute a shell +script, its value is expanded and used as the name of a startup file +to read before executing the script. See Bash Startup Files. + +
    BASH_EXECUTION_STRING
    The command argument to the -c invocation option. + +
    BASH_LINENO
    An array variable whose members are the line numbers in source files +corresponding to each member of FUNCNAME. +${BASH_LINENO[$i]} is the line number in the source file where +${FUNCNAME[$i]} was called. +The corresponding source file name is ${BASH_SOURCE[$i]}. +Use LINENO to obtain the current line number. + +
    BASH_REMATCH
    An array variable whose members are assigned by the `=~' binary +operator to the [[ conditional command +(see Conditional Constructs). +The element with index 0 is the portion of the string +matching the entire regular expression. +The element with index n is the portion of the +string matching the nth parenthesized subexpression. +This variable is read-only. + +
    BASH_SOURCE
    An array variable whose members are the source filenames corresponding +to the elements in the FUNCNAME array variable. + +
    BASH_SUBSHELL
    Incremented by one each time a subshell or subshell environment is spawned. +The initial value is 0. + +
    BASH_VERSINFO
    A readonly array variable (see Arrays) +whose members hold version information for this instance of Bash. +The values assigned to the array members are as follows: + +
    +
    BASH_VERSINFO[0]
    The major version number (the release). + +
    BASH_VERSINFO[1]
    The minor version number (the version). + +
    BASH_VERSINFO[2]
    The patch level. + +
    BASH_VERSINFO[3]
    The build version. + +
    BASH_VERSINFO[4]
    The release status (e.g., beta1). + +
    BASH_VERSINFO[5]
    The value of MACHTYPE. + +
    + +
    BASH_VERSION
    The version number of the current instance of Bash. + +
    COLUMNS
    Used by the select builtin command to determine the terminal width +when printing selection lists. Automatically set upon receipt of a +SIGWINCH. + +
    COMP_CWORD
    An index into ${COMP_WORDS} of the word containing the current +cursor position. +This variable is available only in shell functions invoked by the +programmable completion facilities (see Programmable Completion). + +
    COMP_LINE
    The current command line. +This variable is available only in shell functions and external +commands invoked by the +programmable completion facilities (see Programmable Completion). + +
    COMP_POINT
    The index of the current cursor position relative to the beginning of +the current command. +If the current cursor position is at the end of the current command, +the value of this variable is equal to ${#COMP_LINE}. +This variable is available only in shell functions and external +commands invoked by the +programmable completion facilities (see Programmable Completion). + +
    COMP_TYPE
    Set to an integer value corresponding to the type of completion attempted +that caused a completion function to be called: +TAB, for normal completion, +`?', for listing completions after successive tabs, +`!', for listing alternatives on partial word completion, +`@', to list completions if the word is not unmodified, +or +`%', for menu completion. +This variable is available only in shell functions and external +commands invoked by the +programmable completion facilities (see Programmable Completion). + +
    COMP_KEY
    The key (or final key of a key sequence) used to invoke the current +completion function. + +
    COMP_WORDBREAKS
    The set of characters that the Readline library treats as word +separators when performing word completion. +If COMP_WORDBREAKS is unset, it loses its special properties, +even if it is subsequently reset. + +
    COMP_WORDS
    An array variable consisting of the individual +words in the current command line. +The words are split on shell metacharacters as the shell parser would +separate them. +This variable is available only in shell functions invoked by the +programmable completion facilities (see Programmable Completion). + +
    COMPREPLY
    An array variable from which Bash reads the possible completions +generated by a shell function invoked by the programmable completion +facility (see Programmable Completion). + +
    DIRSTACK
    An array variable containing the current contents of the directory stack. +Directories appear in the stack in the order they are displayed by the +dirs builtin. +Assigning to members of this array variable may be used to modify +directories already in the stack, but the pushd and popd +builtins must be used to add and remove directories. +Assignment to this variable will not change the current directory. +If DIRSTACK is unset, it loses its special properties, even if +it is subsequently reset. + +
    EMACS
    If Bash finds this variable in the environment when the shell +starts with value `t', it assumes that the shell is running in an +emacs shell buffer and disables line editing. + +
    EUID
    The numeric effective user id of the current user. This variable +is readonly. + +
    FCEDIT
    The editor used as a default by the -e option to the fc +builtin command. + +
    FIGNORE
    A colon-separated list of suffixes to ignore when performing +filename completion. +A file name whose suffix matches one of the entries in +FIGNORE +is excluded from the list of matched file names. A sample +value is `.o:~' + +
    FUNCNAME
    An array variable containing the names of all shell functions +currently in the execution call stack. +The element with index 0 is the name of any currently-executing +shell function. +The bottom-most element is "main". +This variable exists only when a shell function is executing. +Assignments to FUNCNAME have no effect and return an error status. +If FUNCNAME is unset, it loses its special properties, even if +it is subsequently reset. + +
    GLOBIGNORE
    A colon-separated list of patterns defining the set of filenames to +be ignored by filename expansion. +If a filename matched by a filename expansion pattern also matches one +of the patterns in GLOBIGNORE, it is removed from the list +of matches. + +
    GROUPS
    An array variable containing the list of groups of which the current +user is a member. +Assignments to GROUPS have no effect and return an error status. +If GROUPS is unset, it loses its special properties, even if it is +subsequently reset. + +
    histchars
    Up to three characters which control history expansion, quick +substitution, and tokenization (see History Interaction). +The first character is the +history expansion character, that is, the character which signifies the +start of a history expansion, normally `!'. The second character is the +character which signifies `quick substitution' when seen as the first +character on a line, normally `^'. The optional third character is the +character which indicates that the remainder of the line is a comment when +found as the first character of a word, usually `#'. The history +comment character causes history substitution to be skipped for the +remaining words on the line. It does not necessarily cause the shell +parser to treat the rest of the line as a comment. + +
    HISTCMD
    The history number, or index in the history list, of the current +command. If HISTCMD is unset, it loses its special properties, +even if it is subsequently reset. + +
    HISTCONTROL
    A colon-separated list of values controlling how commands are saved on +the history list. +If the list of values includes `ignorespace', lines which begin +with a space character are not saved in the history list. +A value of `ignoredups' causes lines which match the previous +history entry to not be saved. +A value of `ignoreboth' is shorthand for +`ignorespace' and `ignoredups'. +A value of `erasedups' causes all previous lines matching the +current line to be removed from the history list before that line +is saved. +Any value not in the above list is ignored. +If HISTCONTROL is unset, or does not include a valid value, +all lines read by the shell parser are saved on the history list, +subject to the value of HISTIGNORE. +The second and subsequent lines of a multi-line compound command are +not tested, and are added to the history regardless of the value of +HISTCONTROL. + +
    HISTFILE
    The name of the file to which the command history is saved. The +default value is ~/.bash_history. + +
    HISTFILESIZE
    The maximum number of lines contained in the history file. When this +variable is assigned a value, the history file is truncated, if +necessary, by removing the oldest entries, +to contain no more than that number of lines. +The history file is also truncated to this size after +writing it when an interactive shell exits. +The default value is 500. + +
    HISTIGNORE
    A colon-separated list of patterns used to decide which command +lines should be saved on the history list. Each pattern is +anchored at the beginning of the line and must match the complete +line (no implicit `*' is appended). Each pattern is tested +against the line after the checks specified by HISTCONTROL +are applied. In addition to the normal shell pattern matching +characters, `&' matches the previous history line. `&' +may be escaped using a backslash; the backslash is removed +before attempting a match. +The second and subsequent lines of a multi-line compound command are +not tested, and are added to the history regardless of the value of +HISTIGNORE. + +

    HISTIGNORE subsumes the function of HISTCONTROL. A +pattern of `&' is identical to ignoredups, and a +pattern of `[ ]*' is identical to ignorespace. +Combining these two patterns, separating them with a colon, +provides the functionality of ignoreboth. + +

    HISTSIZE
    The maximum number of commands to remember on the history list. +The default value is 500. + +
    HISTTIMEFORMAT
    If this variable is set and not null, its value is used as a format string +for strftime to print the time stamp associated with each history +entry displayed by the history builtin. +If this variable is set, time stamps are written to the history file so +they may be preserved across shell sessions. + +
    HOSTFILE
    Contains the name of a file in the same format as /etc/hosts that +should be read when the shell needs to complete a hostname. +The list of possible hostname completions may be changed while the shell +is running; +the next time hostname completion is attempted after the +value is changed, Bash adds the contents of the new file to the +existing list. +If HOSTFILE is set, but has no value, Bash attempts to read +/etc/hosts to obtain the list of possible hostname completions. +When HOSTFILE is unset, the hostname list is cleared. + +
    HOSTNAME
    The name of the current host. + +
    HOSTTYPE
    A string describing the machine Bash is running on. + +
    IGNOREEOF
    Controls the action of the shell on receipt of an EOF character +as the sole input. If set, the value denotes the number +of consecutive EOF characters that can be read as the +first character on an input line +before the shell will exit. If the variable exists but does not +have a numeric value (or has no value) then the default is 10. +If the variable does not exist, then EOF signifies the end of +input to the shell. This is only in effect for interactive shells. + +
    INPUTRC
    The name of the Readline initialization file, overriding the default +of ~/.inputrc. + +
    LANG
    Used to determine the locale category for any category not specifically +selected with a variable starting with LC_. + +
    LC_ALL
    This variable overrides the value of LANG and any other +LC_ variable specifying a locale category. + +
    LC_COLLATE
    This variable determines the collation order used when sorting the +results of filename expansion, and +determines the behavior of range expressions, equivalence classes, +and collating sequences within filename expansion and pattern matching +(see Filename Expansion). + +
    LC_CTYPE
    This variable determines the interpretation of characters and the +behavior of character classes within filename expansion and pattern +matching (see Filename Expansion). + +
    LC_MESSAGES
    This variable determines the locale used to translate double-quoted +strings preceded by a `$' (see Locale Translation). + +
    LC_NUMERIC
    This variable determines the locale category used for number formatting. + +
    LINENO
    The line number in the script or shell function currently executing. + +
    LINES
    Used by the select builtin command to determine the column length +for printing selection lists. Automatically set upon receipt of a +SIGWINCH. + +
    MACHTYPE
    A string that fully describes the system type on which Bash +is executing, in the standard gnu cpu-company-system format. + +
    MAILCHECK
    How often (in seconds) that the shell should check for mail in the +files specified in the MAILPATH or MAIL variables. +The default is 60 seconds. When it is time to check +for mail, the shell does so before displaying the primary prompt. +If this variable is unset, or set to a value that is not a number +greater than or equal to zero, the shell disables mail checking. + +
    OLDPWD
    The previous working directory as set by the cd builtin. + +
    OPTERR
    If set to the value 1, Bash displays error messages +generated by the getopts builtin command. + +
    OSTYPE
    A string describing the operating system Bash is running on. + +
    PIPESTATUS
    An array variable (see Arrays) +containing a list of exit status values from the processes +in the most-recently-executed foreground pipeline (which may +contain only a single command). + +
    POSIXLY_CORRECT
    If this variable is in the environment when bash starts, the shell +enters posix mode (see Bash POSIX Mode) before reading the +startup files, as if the --posix invocation option had been supplied. +If it is set while the shell is running, bash enables posix mode, +as if the command + 
              set -o posix
+
    +

    had been executed. + +

    PPID
    The process id of the shell's parent process. This variable +is readonly. + +
    PROMPT_COMMAND
    If set, the value is interpreted as a command to execute +before the printing of each primary prompt ($PS1). + +
    PS3
    The value of this variable is used as the prompt for the +select command. If this variable is not set, the +select command prompts with `#? ' + +
    PS4
    The value is the prompt printed before the command line is echoed +when the -x option is set (see The Set Builtin). +The first character of PS4 is replicated multiple times, as +necessary, to indicate multiple levels of indirection. +The default is `+ '. + +
    PWD
    The current working directory as set by the cd builtin. + +
    RANDOM
    Each time this parameter is referenced, a random integer +between 0 and 32767 is generated. Assigning a value to this +variable seeds the random number generator. + +
    REPLY
    The default variable for the read builtin. + +
    SECONDS
    This variable expands to the number of seconds since the +shell was started. Assignment to this variable resets +the count to the value assigned, and the expanded value +becomes the value assigned plus the number of seconds +since the assignment. + +
    SHELL
    The full pathname to the shell is kept in this environment variable. +If it is not set when the shell starts, +Bash assigns to it the full pathname of the current user's login shell. + +
    SHELLOPTS
    A colon-separated list of enabled shell options. Each word in +the list is a valid argument for the -o option to the +set builtin command (see The Set Builtin). +The options appearing in SHELLOPTS are those reported +as `on' by `set -o'. +If this variable is in the environment when Bash +starts up, each shell option in the list will be enabled before +reading any startup files. This variable is readonly. + +
    SHLVL
    Incremented by one each time a new instance of Bash is started. This is +intended to be a count of how deeply your Bash shells are nested. + +
    TIMEFORMAT
    The value of this parameter is used as a format string specifying +how the timing information for pipelines prefixed with the time +reserved word should be displayed. +The `%' character introduces an +escape sequence that is expanded to a time value or other +information. +The escape sequences and their meanings are as +follows; the braces denote optional portions. + +
    +
    %%
    A literal `%'. + +
    %[p][l]R
    The elapsed time in seconds. + +
    %[p][l]U
    The number of CPU seconds spent in user mode. + +
    %[p][l]S
    The number of CPU seconds spent in system mode. + +
    %P
    The CPU percentage, computed as (%U + %S) / %R. +
    + +

    The optional p is a digit specifying the precision, the number of +fractional digits after a decimal point. +A value of 0 causes no decimal point or fraction to be output. +At most three places after the decimal point may be specified; values +of p greater than 3 are changed to 3. +If p is not specified, the value 3 is used. + +

    The optional l specifies a longer format, including minutes, of +the form MMmSS.FFs. +The value of p determines whether or not the fraction is included. + +

    If this variable is not set, Bash acts as if it had the value + 

              $'\nreal\t%3lR\nuser\t%3lU\nsys\t%3lS'
+
    +

    If the value is null, no timing information is displayed. +A trailing newline is added when the format string is displayed. + +

    TMOUT
    If set to a value greater than zero, TMOUT is treated as the +default timeout for the read builtin (see Bash Builtins). +The select command (see Conditional Constructs) terminates +if input does not arrive after TMOUT seconds when input is coming +from a terminal. + +

    In an interactive shell, the value is interpreted as +the number of seconds to wait for input after issuing the primary +prompt when the shell is interactive. +Bash terminates after that number of seconds if input does +not arrive. + +

    TMPDIR
    If set, Bash uses its value as the name of a directory in which +Bash creates temporary files for the shell's use. + +
    UID
    The numeric real user id of the current user. This variable is readonly. + +
    + +
    +

    + +Next: , +Previous: Shell Variables, +Up: Top + +
    + +

    6 Bash Features

    + +

    This section describes features unique to Bash. + +

    + +
    +

    + +Next: , +Up: Bash Features + +
    + +

    6.1 Invoking Bash

    + +
         bash [long-opt] [-ir] [-abefhkmnptuvxdBCDHP] [-o option] [-O shopt_option] [argument ...]
+     bash [long-opt] [-abefhkmnptuvxdBCDHP] [-o option] [-O shopt_option] -c string [argument ...]
+     bash [long-opt] -s [-abefhkmnptuvxdBCDHP] [-o option] [-O shopt_option] [argument ...]
+
    +

    In addition to the single-character shell command-line options +(see The Set Builtin), there are several multi-character +options that you can use. These options must appear on the command +line before the single-character options to be recognized. + +

    +
    --debugger
    Arrange for the debugger profile to be executed before the shell +starts. Turns on extended debugging mode (see The Shopt Builtin +for a description of the extdebug option to the shopt +builtin) and shell function tracing +(see The Set Builtin for a description of the -o functrace +option). + +
    --dump-po-strings
    A list of all double-quoted strings preceded by `$' +is printed on the standard output +in the gnu gettext PO (portable object) file format. +Equivalent to -D except for the output format. + +
    --dump-strings
    Equivalent to -D. + +
    --help
    Display a usage message on standard output and exit successfully. + +
    --init-file filename
    --rcfile filename
    Execute commands from filename (instead of ~/.bashrc) +in an interactive shell. + +
    --login
    Equivalent to -l. + +
    --noediting
    Do not use the gnu Readline library (see Command Line Editing) +to read command lines when the shell is interactive. + +
    --noprofile
    Don't load the system-wide startup file /etc/profile +or any of the personal initialization files +~/.bash_profile, ~/.bash_login, or ~/.profile +when Bash is invoked as a login shell. + +
    --norc
    Don't read the ~/.bashrc initialization file in an +interactive shell. This is on by default if the shell is +invoked as sh. + +
    --posix
    Change the behavior of Bash where the default operation differs +from the posix standard to match the standard. This +is intended to make Bash behave as a strict superset of that +standard. See Bash POSIX Mode, for a description of the Bash +posix mode. + +
    --restricted
    Make the shell a restricted shell (see The Restricted Shell). + +
    --verbose
    Equivalent to -v. Print shell input lines as they're read. + +
    --version
    Show version information for this instance of +Bash on the standard output and exit successfully. + +
    + +

    There are several single-character options that may be supplied at +invocation which are not available with the set builtin. + +

    +
    -c string
    Read and execute commands from string after processing the +options, then exit. Any remaining arguments are assigned to the +positional parameters, starting with $0. + +
    -i
    Force the shell to run interactively. Interactive shells are +described in Interactive Shells. + +
    -l
    Make this shell act as if it had been directly invoked by login. +When the shell is interactive, this is equivalent to starting a +login shell with `exec -l bash'. +When the shell is not interactive, the login shell startup files will +be executed. +`exec bash -l' or `exec bash --login' +will replace the current shell with a Bash login shell. +See Bash Startup Files, for a description of the special behavior +of a login shell. + +
    -r
    Make the shell a restricted shell (see The Restricted Shell). + +
    -s
    If this option is present, or if no arguments remain after option +processing, then commands are read from the standard input. +This option allows the positional parameters to be set +when invoking an interactive shell. + +
    -D
    A list of all double-quoted strings preceded by `$' +is printed on the standard output. +These are the strings that +are subject to language translation when the current locale +is not C or POSIX (see Locale Translation). +This implies the -n option; no commands will be executed. + +
    [-+]O [shopt_option]
    shopt_option is one of the shell options accepted by the +shopt builtin (see The Shopt Builtin). +If shopt_option is present, -O sets the value of that option; ++O unsets it. +If shopt_option is not supplied, the names and values of the shell +options accepted by shopt are printed on the standard output. +If the invocation option is +O, the output is displayed in a format +that may be reused as input. + +
    --
    A -- signals the end of options and disables further option +processing. +Any arguments after the -- are treated as filenames and arguments. + +
    + +

    A login shell is one whose first character of argument zero is +`-', or one invoked with the --login option. + +

    An interactive shell is one started without non-option arguments, +unless -s is specified, +without specifying the -c option, and whose input and output are both +connected to terminals (as determined by isatty(3)), or one +started with the -i option. See Interactive Shells, for more +information. + +

    If arguments remain after option processing, and neither the +-c nor the -s +option has been supplied, the first argument is assumed to +be the name of a file containing shell commands (see Shell Scripts). +When Bash is invoked in this fashion, $0 +is set to the name of the file, and the positional parameters +are set to the remaining arguments. +Bash reads and executes commands from this file, then exits. +Bash's exit status is the exit status of the last command executed +in the script. If no commands are executed, the exit status is 0. + +

    +

    + +Next: , +Previous: Invoking Bash, +Up: Bash Features + +
    + +

    6.2 Bash Startup Files

    + +

    +This section describes how Bash executes its startup files. +If any of the files exist but cannot be read, Bash reports an error. +Tildes are expanded in file names as described above under +Tilde Expansion (see Tilde Expansion). + +

    Interactive shells are described in Interactive Shells. + +

    Invoked as an interactive login shell, or with --login
    + +

    When Bash is invoked as an interactive login shell, or as a +non-interactive shell with the --login option, it first reads and +executes commands from the file /etc/profile, if that file exists. +After reading that file, it looks for ~/.bash_profile, +~/.bash_login, and ~/.profile, in that order, and reads +and executes commands from the first one that exists and is readable. +The --noprofile option may be used when the shell is started to +inhibit this behavior. + +

    When a login shell exits, Bash reads and executes commands from +the file ~/.bash_logout, if it exists. + +

    Invoked as an interactive non-login shell
    + +

    When an interactive shell that is not a login shell is started, Bash +reads and executes commands from ~/.bashrc, if that file exists. +This may be inhibited by using the --norc option. +The --rcfile file option will force Bash to read and +execute commands from file instead of ~/.bashrc. + +

    So, typically, your ~/.bash_profile contains the line +

         if [ -f ~/.bashrc ]; then . ~/.bashrc; fi
+
    +

    after (or before) any login-specific initializations. + +

    Invoked non-interactively
    + +

    When Bash is started non-interactively, to run a shell script, +for example, it looks for the variable BASH_ENV in the environment, +expands its value if it appears there, and uses the expanded value as +the name of a file to read and execute. Bash behaves as if the +following command were executed: +

         if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi
+
    +

    but the value of the PATH variable is not used to search for the +file name. + +

    As noted above, if a non-interactive shell is invoked with the +--login option, Bash attempts to read and execute commands from the +login shell startup files. + +

    Invoked with name sh
    + +

    If Bash is invoked with the name sh, it tries to mimic the +startup behavior of historical versions of sh as closely as +possible, while conforming to the posix standard as well. + +

    When invoked as an interactive login shell, or as a non-interactive +shell with the --login option, it first attempts to read +and execute commands from /etc/profile and ~/.profile, in +that order. +The --noprofile option may be used to inhibit this behavior. +When invoked as an interactive shell with the name sh, Bash +looks for the variable ENV, expands its value if it is defined, +and uses the expanded value as the name of a file to read and execute. +Since a shell invoked as sh does not attempt to read and execute +commands from any other startup files, the --rcfile option has +no effect. +A non-interactive shell invoked with the name sh does not attempt +to read any other startup files. + +

    When invoked as sh, Bash enters posix mode after +the startup files are read. + +

    Invoked in posix mode
    + +

    When Bash is started in posix mode, as with the +--posix command line option, it follows the posix standard +for startup files. +In this mode, interactive shells expand the ENV variable +and commands are read and executed from the file whose name is the +expanded value. +No other startup files are read. + +

    Invoked by remote shell daemon
    + +

    Bash attempts to determine when it is being run by the remote shell +daemon, usually rshd. If Bash determines it is being run by +rshd, it reads and executes commands from ~/.bashrc, if that +file exists and is readable. +It will not do this if invoked as sh. +The --norc option may be used to inhibit this behavior, and the +--rcfile option may be used to force another file to be read, but +rshd does not generally invoke the shell with those options or +allow them to be specified. + +

    Invoked with unequal effective and real uid/gids
    + +

    If Bash is started with the effective user (group) id not equal to the +real user (group) id, and the -p option is not supplied, no startup +files are read, shell functions are not inherited from the environment, +the SHELLOPTS variable, if it appears in the environment, is ignored, +and the effective user id is set to the real user id. +If the -p option is supplied at invocation, the startup behavior is +the same, but the effective user id is not reset. + +

    +

    + +Next: , +Previous: Bash Startup Files, +Up: Bash Features + +
    + +

    6.3 Interactive Shells

    + +

    + +

    + +
    +

    + + +Next: , +Up: Interactive Shells + +
    + +

    6.3.1 What is an Interactive Shell?

    + +

    An interactive shell +is one started without non-option arguments, unless -s is +specified, without specifying the -c option, and +whose input and error output are both +connected to terminals (as determined by isatty(3)), +or one started with the -i option. + +

    An interactive shell generally reads from and writes to a user's +terminal. + +

    The -s invocation option may be used to set the positional parameters +when an interactive shell is started. + +

    +

    + + +Next: , +Previous: What is an Interactive Shell?, +Up: Interactive Shells + +
    + +

    6.3.2 Is this Shell Interactive?

    + +

    To determine within a startup script whether or not Bash is +running interactively, +test the value of the `-' special parameter. +It contains i when the shell is interactive. For example: + +

         case "$-" in
+     *i*)	echo This shell is interactive ;;
+     *)	echo This shell is not interactive ;;
+     esac
+
    +

    Alternatively, startup scripts may examine the variable +PS1; it is unset in non-interactive shells, and set in +interactive shells. Thus: + +

         if [ -z "$PS1" ]; then
+             echo This shell is not interactive
+     else
+             echo This shell is interactive
+     fi
+
    +
    +

    + +Previous: Is this Shell Interactive?, +Up: Interactive Shells + +
    + +

    6.3.3 Interactive Shell Behavior

    + +

    When the shell is running interactively, it changes its behavior in +several ways. + +

      +
    1. Startup files are read and executed as described in Bash Startup Files. + +
    2. Job Control (see Job Control) is enabled by default. When job +control is in effect, Bash ignores the keyboard-generated job control +signals SIGTTIN, SIGTTOU, and SIGTSTP. + +
    3. Bash expands and displays PS1 before reading the first line +of a command, and expands and displays PS2 before reading the +second and subsequent lines of a multi-line command. + +
    4. Bash executes the value of the PROMPT_COMMAND variable as a command +before printing the primary prompt, $PS1 +(see Bash Variables). + +
    5. Readline (see Command Line Editing) is used to read commands from +the user's terminal. + +
    6. Bash inspects the value of the ignoreeof option to set -o +instead of exiting immediately when it receives an EOF on its +standard input when reading a command (see The Set Builtin). + +
    7. Command history (see Bash History Facilities) +and history expansion (see History Interaction) +are enabled by default. +Bash will save the command history to the file named by $HISTFILE +when an interactive shell exits. + +
    8. Alias expansion (see Aliases) is performed by default. + +
    9. In the absence of any traps, Bash ignores SIGTERM +(see Signals). + +
    10. In the absence of any traps, SIGINT is caught and handled +((see Signals). +SIGINT will interrupt some shell builtins. + +
    11. An interactive login shell sends a SIGHUP to all jobs on exit +if the huponexit shell option has been enabled (see Signals). + +
    12. The -n invocation option is ignored, and `set -n' has +no effect (see The Set Builtin). + +
    13. Bash will check for mail periodically, depending on the values of the +MAIL, MAILPATH, and MAILCHECK shell variables +(see Bash Variables). + +
    14. Expansion errors due to references to unbound shell variables after +`set -u' has been enabled will not cause the shell to exit +(see The Set Builtin). + +
    15. The shell will not exit on expansion errors caused by var being unset +or null in ${var:?word} expansions +(see Shell Parameter Expansion). + +
    16. Redirection errors encountered by shell builtins will not cause the +shell to exit. + +
    17. When running in posix mode, a special builtin returning an error +status will not cause the shell to exit (see Bash POSIX Mode). + +
    18. A failed exec will not cause the shell to exit +(see Bourne Shell Builtins). + +
    19. Parser syntax errors will not cause the shell to exit. + +
    20. Simple spelling correction for directory arguments to the cd +builtin is enabled by default (see the description of the cdspell +option to the shopt builtin in The Shopt Builtin). + +
    21. The shell will check the value of the TMOUT variable and exit +if a command is not read within the specified number of seconds after +printing $PS1 (see Bash Variables). + +
    + +
    +

    + +Next: , +Previous: Interactive Shells, +Up: Bash Features + +
    + +

    6.4 Bash Conditional Expressions

    + +

    +Conditional expressions are used by the [[ compound command +and the test and [ builtin commands. + +

    Expressions may be unary or binary. +Unary expressions are often used to examine the status of a file. +There are string operators and numeric comparison operators as well. +If the file argument to one of the primaries is of the form +/dev/fd/N, then file descriptor N is checked. +If the file argument to one of the primaries is one of +/dev/stdin, /dev/stdout, or /dev/stderr, file +descriptor 0, 1, or 2, respectively, is checked. + +

    Unless otherwise specified, primaries that operate on files follow symbolic +links and operate on the target of the link, rather than the link itself. + +

    +
    -a file
    True if file exists. + +
    -b file
    True if file exists and is a block special file. + +
    -c file
    True if file exists and is a character special file. + +
    -d file
    True if file exists and is a directory. + +
    -e file
    True if file exists. + +
    -f file
    True if file exists and is a regular file. + +
    -g file
    True if file exists and its set-group-id bit is set. + +
    -h file
    True if file exists and is a symbolic link. + +
    -k file
    True if file exists and its "sticky" bit is set. + +
    -p file
    True if file exists and is a named pipe (FIFO). + +
    -r file
    True if file exists and is readable. + +
    -s file
    True if file exists and has a size greater than zero. + +
    -t fd
    True if file descriptor fd is open and refers to a terminal. + +
    -u file
    True if file exists and its set-user-id bit is set. + +
    -w file
    True if file exists and is writable. + +
    -x file
    True if file exists and is executable. + +
    -O file
    True if file exists and is owned by the effective user id. + +
    -G file
    True if file exists and is owned by the effective group id. + +
    -L file
    True if file exists and is a symbolic link. + +
    -S file
    True if file exists and is a socket. + +
    -N file
    True if file exists and has been modified since it was last read. + +
    file1 -nt file2
    True if file1 is newer (according to modification date) +than file2, or if file1 exists and file2 does not. + +
    file1 -ot file2
    True if file1 is older than file2, +or if file2 exists and file1 does not. + +
    file1 -ef file2
    True if file1 and file2 refer to the same device and +inode numbers. + +
    -o optname
    True if shell option optname is enabled. +The list of options appears in the description of the -o +option to the set builtin (see The Set Builtin). + +
    -z string
    True if the length of string is zero. + +
    -n string
    string
    True if the length of string is non-zero. + +
    string1 == string2
    True if the strings are equal. +`=' may be used in place of `==' for strict posix compliance. + +
    string1 != string2
    True if the strings are not equal. + +
    string1 < string2
    True if string1 sorts before string2 lexicographically +in the current locale. + +
    string1 > string2
    True if string1 sorts after string2 lexicographically +in the current locale. + +
    arg1 OP arg2
    OP is one of +`-eq', `-ne', `-lt', `-le', `-gt', or `-ge'. +These arithmetic binary operators return true if arg1 +is equal to, not equal to, less than, less than or equal to, +greater than, or greater than or equal to arg2, +respectively. Arg1 and arg2 +may be positive or negative integers. + +
    + +
    +

    + +Next: , +Previous: Bash Conditional Expressions, +Up: Bash Features + +
    + +

    6.5 Shell Arithmetic

    + +

    +The shell allows arithmetic expressions to be evaluated, as one of +the shell expansions or by the let and the -i option +to the declare builtins. + +

    Evaluation is done in fixed-width integers with no check for overflow, +though division by 0 is trapped and flagged as an error. +The operators and their precedence, associativity, and values +are the same as in the C language. +The following list of operators is grouped into levels of +equal-precedence operators. +The levels are listed in order of decreasing precedence. + +

    +
    id++ id--
    variable post-increment and post-decrement + +
    ++id --id
    variable pre-increment and pre-decrement + +
    - +
    unary minus and plus + +
    ! ~
    logical and bitwise negation + +
    **
    exponentiation + +
    * / %
    multiplication, division, remainder + +
    + -
    addition, subtraction + +
    << >>
    left and right bitwise shifts + +
    <= >= < >
    comparison + +
    == !=
    equality and inequality + +
    &
    bitwise AND + +
    ^
    bitwise exclusive OR + +
    |
    bitwise OR + +
    &&
    logical AND + +
    ||
    logical OR + +
    expr ? expr : expr
    conditional operator + +
    = *= /= %= += -= <<= >>= &= ^= |=
    assignment + +
    expr1 , expr2
    comma +
    + +

    Shell variables are allowed as operands; parameter expansion is +performed before the expression is evaluated. +Within an expression, shell variables may also be referenced by name +without using the parameter expansion syntax. +A shell variable that is null or unset evaluates to 0 when referenced +by name without using the parameter expansion syntax. +The value of a variable is evaluated as an arithmetic expression +when it is referenced, or when a variable which has been given the +integer attribute using `declare -i' is assigned a value. +A null value evaluates to 0. +A shell variable need not have its integer attribute turned on +to be used in an expression. + +

    Constants with a leading 0 are interpreted as octal numbers. +A leading `0x' or `0X' denotes hexadecimal. Otherwise, +numbers take the form [base#]n, where base +is a decimal number between 2 and 64 representing the arithmetic +base, and n is a number in that base. If base# is +omitted, then base 10 is used. +The digits greater than 9 are represented by the lowercase letters, +the uppercase letters, `@', and `_', in that order. +If base is less than or equal to 36, lowercase and uppercase +letters may be used interchangeably to represent numbers between 10 +and 35. + +

    Operators are evaluated in order of precedence. Sub-expressions in +parentheses are evaluated first and may override the precedence +rules above. + +

    +

    + +Next: , +Previous: Shell Arithmetic, +Up: Bash Features + +
    + +

    6.6 Aliases

    + +

    +Aliases allow a string to be substituted for a word when it is used +as the first word of a simple command. +The shell maintains a list of aliases that may be set and unset with +the alias and unalias builtin commands. + +

    The first word of each simple command, if unquoted, is checked to see +if it has an alias. +If so, that word is replaced by the text of the alias. +The characters `/', `$', ``', `=' and any of the +shell metacharacters or quoting characters listed above may not appear +in an alias name. +The replacement text may contain any valid +shell input, including shell metacharacters. +The first word of the replacement text is tested for +aliases, but a word that is identical to an alias being expanded +is not expanded a second time. +This means that one may alias ls to "ls -F", +for instance, and Bash does not try to recursively expand the +replacement text. If the last character of the alias value is a +space or tab character, then the next command word following the +alias is also checked for alias expansion. + +

    Aliases are created and listed with the alias +command, and removed with the unalias command. + +

    There is no mechanism for using arguments in the replacement text, +as in csh. +If arguments are needed, a shell function should be used +(see Shell Functions). + +

    Aliases are not expanded when the shell is not interactive, +unless the expand_aliases shell option is set using +shopt (see The Shopt Builtin). + +

    The rules concerning the definition and use of aliases are +somewhat confusing. Bash +always reads at least one complete line +of input before executing any +of the commands on that line. Aliases are expanded when a +command is read, not when it is executed. Therefore, an +alias definition appearing on the same line as another +command does not take effect until the next line of input is read. +The commands following the alias definition +on that line are not affected by the new alias. +This behavior is also an issue when functions are executed. +Aliases are expanded when a function definition is read, +not when the function is executed, because a function definition +is itself a compound command. As a consequence, aliases +defined in a function are not available until after that +function is executed. To be safe, always put +alias definitions on a separate line, and do not use alias +in compound commands. + +

    For almost every purpose, shell functions are preferred over aliases. + +

    +

    + +Next: , +Previous: Aliases, +Up: Bash Features + +
    + +

    6.7 Arrays

    + +

    +Bash provides one-dimensional array variables. Any variable may be used as +an array; the declare builtin will explicitly declare an array. +There is no maximum +limit on the size of an array, nor any requirement that members +be indexed or assigned contiguously. Arrays are zero-based. + +

    An array is created automatically if any variable is assigned to using +the syntax +

         name[subscript]=value
+
    +

    The subscript +is treated as an arithmetic expression that must evaluate to a number +greater than or equal to zero. To explicitly declare an array, use +

         declare -a name
+
    +

    The syntax +

         declare -a name[subscript]
+
    +

    is also accepted; the subscript is ignored. Attributes may be +specified for an array variable using the declare and +readonly builtins. Each attribute applies to all members of +an array. + +

    Arrays are assigned to using compound assignments of the form +

         name=(value1 ... valuen)
+
    +

    where each +value is of the form [[subscript]=]string. If +the optional subscript is supplied, that index is assigned to; +otherwise the index of the element assigned is the last index assigned +to by the statement plus one. Indexing starts at zero. +This syntax is also accepted by the declare +builtin. Individual array elements may be assigned to using the +name[subscript]=value syntax introduced above. + +

    Any element of an array may be referenced using +${name[subscript]}. +The braces are required to avoid +conflicts with the shell's filename expansion operators. If the +subscript is `@' or `*', the word expands to all members +of the array name. These subscripts differ only when the word +appears within double quotes. +If the word is double-quoted, +${name[*]} expands to a single word with +the value of each array member separated by the first character of the +IFS variable, and ${name[@]} expands each element of +name to a separate word. When there are no array members, +${name[@]} expands to nothing. +If the double-quoted expansion occurs within a word, the expansion of +the first parameter is joined with the beginning part of the original +word, and the expansion of the last parameter is joined with the last +part of the original word. +This is analogous to the +expansion of the special parameters `@' and `*'. +${#name[subscript]} expands to the length of +${name[subscript]}. +If subscript is `@' or +`*', the expansion is the number of elements in the array. +Referencing an array variable without a subscript is equivalent to +referencing element zero. + +

    The unset builtin is used to destroy arrays. +unset name[subscript] +destroys the array element at index subscript. +Care must be taken to avoid unwanted side effects caused by filename +generation. +unset name, where name is an array, removes the +entire array. A subscript of `*' or `@' also removes the +entire array. + +

    The declare, local, and readonly +builtins each accept a -a +option to specify an array. The read +builtin accepts a -a +option to assign a list of words read from the standard input +to an array, and can read values from the standard input into +individual array elements. The set and declare +builtins display array values in a way that allows them to be +reused as input. + +

    +

    + +Next: , +Previous: Arrays, +Up: Bash Features + +
    + +

    6.8 The Directory Stack

    + +

    + +

    + +

    The directory stack is a list of recently-visited directories. The +pushd builtin adds directories to the stack as it changes +the current directory, and the popd builtin removes specified +directories from the stack and changes the current directory to +the directory removed. The dirs builtin displays the contents +of the directory stack. + +

    The contents of the directory stack are also visible +as the value of the DIRSTACK shell variable. + +

    +

    + +Up: The Directory Stack + +
    + +

    6.8.1 Directory Stack Builtins

    + +
    +
    dirs
    + 
              dirs [+N | -N] [-clpv]
+
    +

    Display the list of currently remembered directories. Directories +are added to the list with the pushd command; the +popd command removes directories from the list. +

    +
    +N
    Displays the Nth directory (counting from the left of the +list printed by dirs when invoked without options), starting +with zero. +
    -N
    Displays the Nth directory (counting from the right of the +list printed by dirs when invoked without options), starting +with zero. +
    -c
    Clears the directory stack by deleting all of the elements. +
    -l
    Produces a longer listing; the default listing format uses a +tilde to denote the home directory. +
    -p
    Causes dirs to print the directory stack with one entry per +line. +
    -v
    Causes dirs to print the directory stack with one entry per +line, prefixing each entry with its index in the stack. +
    + +
    popd
    + 
              popd [+N | -N] [-n]
+
    +

    Remove the top entry from the directory stack, and cd +to the new top directory. +When no arguments are given, popd +removes the top directory from the stack and +performs a cd to the new top directory. The +elements are numbered from 0 starting at the first directory listed with +dirs; i.e., popd is equivalent to popd +0. +

    +
    +N
    Removes the Nth directory (counting from the left of the +list printed by dirs), starting with zero. +
    -N
    Removes the Nth directory (counting from the right of the +list printed by dirs), starting with zero. +
    -n
    Suppresses the normal change of directory when removing directories +from the stack, so that only the stack is manipulated. +
    + +


    pushd
    + 
              pushd [-n] [+N | -N | dir ]
+
    +

    Save the current directory on the top of the directory stack +and then cd to dir. +With no arguments, pushd exchanges the top two directories. + +

    +
    -n
    Suppresses the normal change of directory when adding directories +to the stack, so that only the stack is manipulated. +
    +N
    Brings the Nth directory (counting from the left of the +list printed by dirs, starting with zero) to the top of +the list by rotating the stack. +
    -N
    Brings the Nth directory (counting from the right of the +list printed by dirs, starting with zero) to the top of +the list by rotating the stack. +
    dir
    Makes the current working directory be the top of the stack, and then +executes the equivalent of `cd dir'. +cds to dir. +
    + +
    + +
    +

    + +Next: , +Previous: The Directory Stack, +Up: Bash Features + +
    + +

    6.9 Controlling the Prompt

    + +

    +The value of the variable PROMPT_COMMAND is examined just before +Bash prints each primary prompt. If PROMPT_COMMAND is set and +has a non-null value, then the +value is executed just as if it had been typed on the command line. + +

    In addition, the following table describes the special characters which +can appear in the prompt variables: + +

    +
    \a
    A bell character. +
    \d
    The date, in "Weekday Month Date" format (e.g., "Tue May 26"). +
    \D{format}
    The format is passed to strftime(3) and the result is inserted +into the prompt string; an empty format results in a locale-specific +time representation. The braces are required. +
    \e
    An escape character. +
    \h
    The hostname, up to the first `.'. +
    \H
    The hostname. +
    \j
    The number of jobs currently managed by the shell. +
    \l
    The basename of the shell's terminal device name. +
    \n
    A newline. +
    \r
    A carriage return. +
    \s
    The name of the shell, the basename of $0 (the portion +following the final slash). +
    \t
    The time, in 24-hour HH:MM:SS format. +
    \T
    The time, in 12-hour HH:MM:SS format. +
    \@
    The time, in 12-hour am/pm format. +
    \A
    The time, in 24-hour HH:MM format. +
    \u
    The username of the current user. +
    \v
    The version of Bash (e.g., 2.00) +
    \V
    The release of Bash, version + patchlevel (e.g., 2.00.0) +
    \w
    The current working directory, with $HOME abbreviated with a tilde. +
    \W
    The basename of $PWD, with $HOME abbreviated with a tilde. +
    \!
    The history number of this command. +
    \#
    The command number of this command. +
    \$
    If the effective uid is 0, #, otherwise $. +
    \nnn
    The character whose ASCII code is the octal value nnn. +
    \\
    A backslash. +
    \[
    Begin a sequence of non-printing characters. This could be used to +embed a terminal control sequence into the prompt. +
    \]
    End a sequence of non-printing characters. +
    + +

    The command number and the history number are usually different: +the history number of a command is its position in the history +list, which may include commands restored from the history file +(see Bash History Facilities), while the command number is +the position in the sequence of commands executed during the current +shell session. + +

    After the string is decoded, it is expanded via +parameter expansion, command substitution, arithmetic +expansion, and quote removal, subject to the value of the +promptvars shell option (see Bash Builtins). + +

    +

    + +Next: , +Previous: Printing a Prompt, +Up: Bash Features + +
    + +

    6.10 The Restricted Shell

    + +

    +If Bash is started with the name rbash, or the +--restricted +or +-r +option is supplied at invocation, the shell becomes restricted. +A restricted shell is used to +set up an environment more controlled than the standard shell. +A restricted shell behaves identically to bash +with the exception that the following are disallowed or not performed: + +

      +
    • Changing directories with the cd builtin. +
    • Setting or unsetting the values of the SHELL, PATH, +ENV, or BASH_ENV variables. +
    • Specifying command names containing slashes. +
    • Specifying a filename containing a slash as an argument to the . +builtin command. +
    • Specifying a filename containing a slash as an argument to the -p +option to the hash builtin command. +
    • Importing function definitions from the shell environment at startup. +
    • Parsing the value of SHELLOPTS from the shell environment at startup. +
    • Redirecting output using the `>', `>|', `<>', `>&', +`&>', and `>>' redirection operators. +
    • Using the exec builtin to replace the shell with another command. +
    • Adding or deleting builtin commands with the +-f and -d options to the enable builtin. +
    • Using the enable builtin command to enable disabled shell builtins. +
    • Specifying the -p option to the command builtin. +
    • Turning off restricted mode with `set +r' or `set +o restricted'. +
    + +

    These restrictions are enforced after any startup files are read. + +

    When a command that is found to be a shell script is executed +(see Shell Scripts), rbash turns off any restrictions in +the shell spawned to execute the script. + +

    +

    + +Previous: The Restricted Shell, +Up: Bash Features + +
    + +

    6.11 Bash POSIX Mode

    + +

    +Starting Bash with the --posix command-line option or executing +`set -o posix' while Bash is running will cause Bash to conform more +closely to the posix standard by changing the behavior to +match that specified by posix in areas where the Bash default differs. + +

    When invoked as sh, Bash enters posix mode after reading the +startup files. + +

    The following list is what's changed when `posix mode' is in effect: + +

      +
    1. When a command in the hash table no longer exists, Bash will re-search +$PATH to find the new location. This is also available with +`shopt -s checkhash'. + +
    2. The message printed by the job control code and builtins when a job +exits with a non-zero status is `Done(status)'. + +
    3. The message printed by the job control code and builtins when a job +is stopped is `Stopped(signame)', where signame is, for +example, SIGTSTP. + +
    4. The bg builtin uses the required format to describe each job placed +in the background, which does not include an indication of whether the job +is the current or previous job. + +
    5. Reserved words appearing in a context where reserved words are recognized +do not undergo alias expansion. + +
    6. The posix PS1 and PS2 expansions of `!' to +the history number and `!!' to `!' are enabled, +and parameter expansion is performed on the values of PS1 and +PS2 regardless of the setting of the promptvars option. + +
    7. The posix startup files are executed ($ENV) rather than +the normal Bash files. + +
    8. Tilde expansion is only performed on assignments preceding a command +name, rather than on all assignment statements on the line. + +
    9. The default history file is ~/.sh_history (this is the +default value of $HISTFILE). + +
    10. The output of `kill -l' prints all the signal names on a single line, +separated by spaces, without the `SIG' prefix. + +
    11. The kill builtin does not accept signal names with a `SIG' +prefix. + +
    12. Non-interactive shells exit if filename in . filename +is not found. + +
    13. Non-interactive shells exit if a syntax error in an arithmetic expansion +results in an invalid expression. + +
    14. Redirection operators do not perform filename expansion on the word +in the redirection unless the shell is interactive. + +
    15. Redirection operators do not perform word splitting on the word in the +redirection. + +
    16. Function names must be valid shell names. That is, they may not +contain characters other than letters, digits, and underscores, and +may not start with a digit. Declaring a function with an invalid name +causes a fatal syntax error in non-interactive shells. + +
    17. posix special builtins are found before shell functions +during command lookup. + +
    18. If a posix special builtin returns an error status, a +non-interactive shell exits. The fatal errors are those listed in +the POSIX standard, and include things like passing incorrect options, +redirection errors, variable assignment errors for assignments preceding +the command name, and so on. + +
    19. If CDPATH is set, the cd builtin will not implicitly +append the current directory to it. This means that cd will +fail if no valid directory name can be constructed from +any of the entries in $CDPATH, even if the a directory with +the same name as the name given as an argument to cd exists +in the current directory. + +
    20. A non-interactive shell exits with an error status if a variable +assignment error occurs when no command name follows the assignment +statements. +A variable assignment error occurs, for example, when trying to assign +a value to a readonly variable. + +
    21. A non-interactive shell exits with an error status if the iteration +variable in a for statement or the selection variable in a +select statement is a readonly variable. + +
    22. Process substitution is not available. + +
    23. Assignment statements preceding posix special builtins +persist in the shell environment after the builtin completes. + +
    24. Assignment statements preceding shell function calls persist in the +shell environment after the function returns, as if a posix +special builtin command had been executed. + +
    25. The export and readonly builtin commands display their +output in the format required by posix. + +
    26. The trap builtin displays signal names without the leading +SIG. + +
    27. The trap builtin doesn't check the first argument for a possible +signal specification and revert the signal handling to the original +disposition if it is, unless that argument consists solely of digits and +is a valid signal number. If users want to reset the handler for a given +signal to the original disposition, they should use `-' as the +first argument. + +
    28. The . and source builtins do not search the current directory +for the filename argument if it is not found by searching PATH. + +
    29. Subshells spawned to execute command substitutions inherit the value of +the -e option from the parent shell. When not in posix mode, +Bash clears the -e option in such subshells. + +
    30. Alias expansion is always enabled, even in non-interactive shells. + +
    31. When the alias builtin displays alias definitions, it does not +display them with a leading `alias ' unless the -p option +is supplied. + +
    32. When the set builtin is invoked without options, it does not display +shell function names and definitions. + +
    33. When the set builtin is invoked without options, it displays +variable values without quotes, unless they contain shell metacharacters, +even if the result contains nonprinting characters. + +
    34. When the cd builtin is invoked in logical mode, and the pathname +constructed from $PWD and the directory name supplied as an argument +does not refer to an existing directory, cd will fail instead of +falling back to physical mode. + +
    35. When the pwd builtin is supplied the -P option, it resets +$PWD to a pathname containing no symlinks. + +
    36. The pwd builtin verifies that the value it prints is the same as the +current directory, even if it is not asked to check the file system with the +-P option. + +
    37. When listing the history, the fc builtin does not include an +indication of whether or not a history entry has been modified. + +
    38. The default editor used by fc is ed. + +
    39. The type and command builtins will not report a non-executable +file as having been found, though the shell will attempt to execute such a +file if it is the only so-named file found in $PATH. + +
    40. The vi editing mode will invoke the vi editor directly when +the `v' command is run, instead of checking $FCEDIT and +$EDITOR. + +
    41. When the xpg_echo option is enabled, Bash does not attempt to interpret +any arguments to echo as options. Each argument is displayed, after +escape characters are converted. + +
    + +

    There is other posix behavior that Bash does not implement by +default even when in posix mode. +Specifically: + +

      + +
    1. The fc builtin checks $EDITOR as a program to edit history +entries if FCEDIT is unset, rather than defaulting directly to +ed. fc uses ed if EDITOR is unset. + +
    2. As noted above, Bash requires the xpg_echo option to be enabled for +the echo builtin to be fully conformant. + +
    + +

    Bash can be configured to be posix-conformant by default, by specifying +the --enable-strict-posix-default to configure when building +(see Optional Features). + +

    +

    + +Next: , +Previous: Bash Features, +Up: Top + +
    + +

    7 Job Control

    + +

    This chapter discusses what job control is, how it works, and how +Bash allows you to access its facilities. + +

    + +
    +

    + +Next: , +Up: Job Control + +
    + +

    7.1 Job Control Basics

    + +

    +Job control +refers to the ability to selectively stop (suspend) +the execution of processes and continue (resume) +their execution at a later point. A user typically employs +this facility via an interactive interface supplied jointly +by the system's terminal driver and Bash. + +

    The shell associates a job with each pipeline. It keeps a +table of currently executing jobs, which may be listed with the +jobs command. When Bash starts a job +asynchronously, it prints a line that looks +like: +

         [1] 25647
+
    +

    indicating that this job is job number 1 and that the process id +of the last process in the pipeline associated with this job is +25647. All of the processes in a single pipeline are members of +the same job. Bash uses the job abstraction as the +basis for job control. + +

    To facilitate the implementation of the user interface to job +control, the operating system maintains the notion of a current terminal +process group id. Members of this process group (processes whose +process group id is equal to the current terminal process group +id) receive keyboard-generated signals such as SIGINT. +These processes are said to be in the foreground. Background +processes are those whose process group id differs from the +terminal's; such processes are immune to keyboard-generated +signals. Only foreground processes are allowed to read from or +write to the terminal. Background processes which attempt to +read from (write to) the terminal are sent a SIGTTIN +(SIGTTOU) signal by the terminal driver, which, unless +caught, suspends the process. + +

    If the operating system on which Bash is running supports +job control, Bash contains facilities to use it. Typing the +suspend character (typically `^Z', Control-Z) while a +process is running causes that process to be stopped and returns +control to Bash. Typing the delayed suspend character +(typically `^Y', Control-Y) causes the process to be stopped +when it attempts to read input from the terminal, and control to +be returned to Bash. The user then manipulates the state of +this job, using the bg command to continue it in the +background, the fg command to continue it in the +foreground, or the kill command to kill it. A `^Z' +takes effect immediately, and has the additional side effect of +causing pending output and typeahead to be discarded. + +

    There are a number of ways to refer to a job in the shell. The +character `%' introduces a job name. + +

    Job number n may be referred to as `%n'. +The symbols `%%' and `%+' refer to the shell's notion of the +current job, which is the last job stopped while it was in the foreground +or started in the background. +A single `%' (with no accompanying job specification) also refers +to the current job. +The previous job may be referenced using `%-'. In output +pertaining to jobs (e.g., the output of the jobs command), +the current job is always flagged with a `+', and the +previous job with a `-'. + +

    A job may also be referred to +using a prefix of the name used to start it, or using a substring +that appears in its command line. For example, `%ce' refers +to a stopped ce job. Using `%?ce', on the +other hand, refers to any job containing the string `ce' in +its command line. If the prefix or substring matches more than one job, +Bash reports an error. + +

    Simply naming a job can be used to bring it into the foreground: +`%1' is a synonym for `fg %1', bringing job 1 from the +background into the foreground. Similarly, `%1 &' resumes +job 1 in the background, equivalent to `bg %1' + +

    The shell learns immediately whenever a job changes state. +Normally, Bash waits until it is about to print a prompt +before reporting changes in a job's status so as to not interrupt +any other output. +If the -b option to the set builtin is enabled, +Bash reports such changes immediately (see The Set Builtin). +Any trap on SIGCHLD is executed for each child process +that exits. + +

    If an attempt to exit Bash is made while jobs are stopped, (or running, if +the checkjobs option is enabled – see The Shopt Builtin), the +shell prints a warning message, and if the checkjobs option is +enabled, lists the jobs and their statuses. +The jobs command may then be used to inspect their status. +If a second attempt to exit is made without an intervening command, +Bash does not print another warning, and any stopped jobs are terminated. + +

    +

    + +Next: , +Previous: Job Control Basics, +Up: Job Control + +
    + +

    7.2 Job Control Builtins

    + +
    +
    bg
    + 
              bg [jobspec ...]
+
    +

    Resume each suspended job jobspec in the background, as if it +had been started with `&'. +If jobspec is not supplied, the current job is used. +The return status is zero unless it is run when job control is not +enabled, or, when run with job control enabled, any +jobspec was not found or specifies a job +that was started without job control. + +

    fg
    + 
              fg [jobspec]
+
    +

    Resume the job jobspec in the foreground and make it the current job. +If jobspec is not supplied, the current job is used. +The return status is that of the command placed into the foreground, +or non-zero if run when job control is disabled or, when run with +job control enabled, jobspec does not specify a valid job or +jobspec specifies a job that was started without job control. + +

    jobs
    + 
              jobs [-lnprs] [jobspec]
+          jobs -x command [arguments]
+
    +

    The first form lists the active jobs. The options have the +following meanings: + +

    +
    -l
    List process ids in addition to the normal information. + +
    -n
    Display information only about jobs that have changed status since +the user was last notified of their status. + +
    -p
    List only the process id of the job's process group leader. + +
    -r
    Restrict output to running jobs. + +
    -s
    Restrict output to stopped jobs. +
    + +

    If jobspec is given, +output is restricted to information about that job. +If jobspec is not supplied, the status of all jobs is +listed. + +

    If the -x option is supplied, jobs replaces any +jobspec found in command or arguments with the +corresponding process group id, and executes command, +passing it arguments, returning its exit status. + +

    kill
    + 
              kill [-s sigspec] [-n signum] [-sigspec] jobspec or pid
+          kill -l [exit_status]
+
    +

    Send a signal specified by sigspec or signum to the process +named by job specification jobspec or process id pid. +sigspec is either a case-insensitive signal name such as +SIGINT (with or without the SIG prefix) +or a signal number; signum is a signal number. +If sigspec and signum are not present, SIGTERM is used. +The -l option lists the signal names. +If any arguments are supplied when -l is given, the names of the +signals corresponding to the arguments are listed, and the return status +is zero. +exit_status is a number specifying a signal number or the exit +status of a process terminated by a signal. +The return status is zero if at least one signal was successfully sent, +or non-zero if an error occurs or an invalid option is encountered. + +

    wait
    + 
              wait [jobspec or pid ...]
+
    +

    Wait until the child process specified by each process id pid +or job specification jobspec exits and return the exit status of the +last command waited for. +If a job spec is given, all processes in the job are waited for. +If no arguments are given, all currently active child processes are +waited for, and the return status is zero. +If neither jobspec nor pid specifies an active child process +of the shell, the return status is 127. + +

    disown
    + 
              disown [-ar] [-h] [jobspec ...]
+
    +

    Without options, each jobspec is removed from the table of +active jobs. +If the -h option is given, the job is not removed from the table, +but is marked so that SIGHUP is not sent to the job if the shell +receives a SIGHUP. +If jobspec is not present, and neither the -a nor -r +option is supplied, the current job is used. +If no jobspec is supplied, the -a option means to remove or +mark all jobs; the -r option without a jobspec +argument restricts operation to running jobs. + +

    suspend
    + 
              suspend [-f]
+
    +

    Suspend the execution of this shell until it receives a +SIGCONT signal. The -f option means to suspend +even if the shell is a login shell. + +

    + +

    When job control is not active, the kill and wait +builtins do not accept jobspec arguments. They must be +supplied process ids. + +

    +

    + +Previous: Job Control Builtins, +Up: Job Control + +
    + +

    7.3 Job Control Variables

    + +
    +
    auto_resume
    This variable controls how the shell interacts with the user and +job control. If this variable exists then single word simple +commands without redirections are treated as candidates for resumption +of an existing job. There is no ambiguity allowed; if there is +more than one job beginning with the string typed, then +the most recently accessed job will be selected. +The name of a stopped job, in this context, is the command line +used to start it. If this variable is set to the value `exact', +the string supplied must match the name of a stopped job exactly; +if set to `substring', +the string supplied needs to match a substring of the name of a +stopped job. The `substring' value provides functionality +analogous to the `%?' job id (see Job Control Basics). +If set to any other value, the supplied string must +be a prefix of a stopped job's name; this provides functionality +analogous to the `%' job id. + +
    + +

    + + + + + +

    +

    + +Next: , +Previous: Using History Interactively, +Up: Top + +
    + +

    8 Command Line Editing

    + +

    This chapter describes the basic features of the gnu +command line editing interface. +Command line editing is provided by the Readline library, which is +used by several different programs, including Bash. + +

    + +
    +

    + +Next: , +Up: Command Line Editing + +
    + +

    8.1 Introduction to Line Editing

    + +

    The following paragraphs describe the notation used to represent +keystrokes. + +

    The text C-k is read as `Control-K' and describes the character +produced when the <k> key is pressed while the Control key +is depressed. + +

    The text M-k is read as `Meta-K' and describes the character +produced when the Meta key (if you have one) is depressed, and the <k> +key is pressed. +The Meta key is labeled <ALT> on many keyboards. +On keyboards with two keys labeled <ALT> (usually to either side of +the space bar), the <ALT> on the left side is generally set to +work as a Meta key. +The <ALT> key on the right may also be configured to work as a +Meta key or may be configured as some other modifier, such as a +Compose key for typing accented characters. + +

    If you do not have a Meta or <ALT> key, or another key working as +a Meta key, the identical keystroke can be generated by typing <ESC> +first, and then typing <k>. +Either process is known as metafying the <k> key. + +

    The text M-C-k is read as `Meta-Control-k' and describes the +character produced by metafying C-k. + +

    In addition, several keys have their own names. Specifically, +<DEL>, <ESC>, <LFD>, <SPC>, <RET>, and <TAB> all +stand for themselves when seen in this text, or in an init file +(see Readline Init File). +If your keyboard lacks a <LFD> key, typing <C-j> will +produce the desired character. +The <RET> key may be labeled <Return> or <Enter> on +some keyboards. + +

    +

    + +Next: , +Previous: Introduction and Notation, +Up: Command Line Editing + +
    + +

    8.2 Readline Interaction

    + +

    +Often during an interactive session you type in a long line of text, +only to notice that the first word on the line is misspelled. The +Readline library gives you a set of commands for manipulating the text +as you type it in, allowing you to just fix your typo, and not forcing +you to retype the majority of the line. Using these editing commands, +you move the cursor to the place that needs correction, and delete or +insert the text of the corrections. Then, when you are satisfied with +the line, you simply press <RET>. You do not have to be at the +end of the line to press <RET>; the entire line is accepted +regardless of the location of the cursor within the line. + +

    + +
    +

    + +Next: , +Up: Readline Interaction + +
    + +

    8.2.1 Readline Bare Essentials

    + +

    +In order to enter characters into the line, simply type them. The typed +character appears where the cursor was, and then the cursor moves one +space to the right. If you mistype a character, you can use your +erase character to back up and delete the mistyped character. + +

    Sometimes you may mistype a character, and +not notice the error until you have typed several other characters. In +that case, you can type C-b to move the cursor to the left, and then +correct your mistake. Afterwards, you can move the cursor to the right +with C-f. + +

    When you add text in the middle of a line, you will notice that characters +to the right of the cursor are `pushed over' to make room for the text +that you have inserted. Likewise, when you delete text behind the cursor, +characters to the right of the cursor are `pulled back' to fill in the +blank space created by the removal of the text. A list of the bare +essentials for editing the text of an input line follows. + +

    +
    C-b
    Move back one character. +
    C-f
    Move forward one character. +
    <DEL> or <Backspace>
    Delete the character to the left of the cursor. +
    C-d
    Delete the character underneath the cursor. +
    Printing characters
    Insert the character into the line at the cursor. +
    C-_ or C-x C-u
    Undo the last editing command. You can undo all the way back to an +empty line. +
    + +

    (Depending on your configuration, the <Backspace> key be set to +delete the character to the left of the cursor and the <DEL> key set +to delete the character underneath the cursor, like C-d, rather +than the character to the left of the cursor.) + +

    +

    + +Next: , +Previous: Readline Bare Essentials, +Up: Readline Interaction + +
    + +

    8.2.2 Readline Movement Commands

    + +

    The above table describes the most basic keystrokes that you need +in order to do editing of the input line. For your convenience, many +other commands have been added in addition to C-b, C-f, +C-d, and <DEL>. Here are some commands for moving more rapidly +about the line. + +

    +
    C-a
    Move to the start of the line. +
    C-e
    Move to the end of the line. +
    M-f
    Move forward a word, where a word is composed of letters and digits. +
    M-b
    Move backward a word. +
    C-l
    Clear the screen, reprinting the current line at the top. +
    + +

    Notice how C-f moves forward a character, while M-f moves +forward a word. It is a loose convention that control keystrokes +operate on characters while meta keystrokes operate on words. + +

    +

    + +Next: , +Previous: Readline Movement Commands, +Up: Readline Interaction + +
    + +

    8.2.3 Readline Killing Commands

    + +

    +Killing text means to delete the text from the line, but to save +it away for later use, usually by yanking (re-inserting) +it back into the line. +(`Cut' and `paste' are more recent jargon for `kill' and `yank'.) + +

    If the description for a command says that it `kills' text, then you can +be sure that you can get the text back in a different (or the same) +place later. + +

    When you use a kill command, the text is saved in a kill-ring. +Any number of consecutive kills save all of the killed text together, so +that when you yank it back, you get it all. The kill +ring is not line specific; the text that you killed on a previously +typed line is available to be yanked back later, when you are typing +another line. + +Here is the list of commands for killing text. + +

    +
    C-k
    Kill the text from the current cursor position to the end of the line. + +
    M-d
    Kill from the cursor to the end of the current word, or, if between +words, to the end of the next word. +Word boundaries are the same as those used by M-f. + +
    M-<DEL>
    Kill from the cursor the start of the current word, or, if between +words, to the start of the previous word. +Word boundaries are the same as those used by M-b. + +
    C-w
    Kill from the cursor to the previous whitespace. This is different than +M-<DEL> because the word boundaries differ. + +
    + +

    Here is how to yank the text back into the line. Yanking +means to copy the most-recently-killed text from the kill buffer. + +

    +
    C-y
    Yank the most recently killed text back into the buffer at the cursor. + +
    M-y
    Rotate the kill-ring, and yank the new top. You can only do this if +the prior command is C-y or M-y. +
    + +
    +

    + +Next: , +Previous: Readline Killing Commands, +Up: Readline Interaction + +
    + +

    8.2.4 Readline Arguments

    + +

    You can pass numeric arguments to Readline commands. Sometimes the +argument acts as a repeat count, other times it is the sign of the +argument that is significant. If you pass a negative argument to a +command which normally acts in a forward direction, that command will +act in a backward direction. For example, to kill text back to the +start of the line, you might type `M-- C-k'. + +

    The general way to pass numeric arguments to a command is to type meta +digits before the command. If the first `digit' typed is a minus +sign (`-'), then the sign of the argument will be negative. Once +you have typed one meta digit to get the argument started, you can type +the remainder of the digits, and then the command. For example, to give +the C-d command an argument of 10, you could type `M-1 0 C-d', +which will delete the next ten characters on the input line. + +

    +

    + +Previous: Readline Arguments, +Up: Readline Interaction + +
    + +

    8.2.5 Searching for Commands in the History

    + +

    Readline provides commands for searching through the command history +(see Bash History Facilities) +for lines containing a specified string. +There are two search modes: incremental and non-incremental. + +

    Incremental searches begin before the user has finished typing the +search string. +As each character of the search string is typed, Readline displays +the next entry from the history matching the string typed so far. +An incremental search requires only as many characters as needed to +find the desired history entry. +To search backward in the history for a particular string, type +C-r. Typing C-s searches forward through the history. +The characters present in the value of the isearch-terminators variable +are used to terminate an incremental search. +If that variable has not been assigned a value, the <ESC> and +C-J characters will terminate an incremental search. +C-g will abort an incremental search and restore the original line. +When the search is terminated, the history entry containing the +search string becomes the current line. + +

    To find other matching entries in the history list, type C-r or +C-s as appropriate. +This will search backward or forward in the history for the next +entry matching the search string typed so far. +Any other key sequence bound to a Readline command will terminate +the search and execute that command. +For instance, a <RET> will terminate the search and accept +the line, thereby executing the command from the history list. +A movement command will terminate the search, make the last line found +the current line, and begin editing. + +

    Readline remembers the last incremental search string. If two +C-rs are typed without any intervening characters defining a new +search string, any remembered search string is used. + +

    Non-incremental searches read the entire search string before starting +to search for matching history lines. The search string may be +typed by the user or be part of the contents of the current line. + +

    +

    + +Next: , +Previous: Readline Interaction, +Up: Command Line Editing + +
    + +

    8.3 Readline Init File

    + +

    +Although the Readline library comes with a set of Emacs-like +keybindings installed by default, it is possible to use a different set +of keybindings. +Any user can customize programs that use Readline by putting +commands in an inputrc file, conventionally in his home directory. +The name of this +file is taken from the value of the shell variable INPUTRC. If +that variable is unset, the default is ~/.inputrc. If that +file does not exist or cannot be read, the ultimate default is +/etc/inputrc. + +

    When a program which uses the Readline library starts up, the +init file is read, and the key bindings are set. + +

    In addition, the C-x C-r command re-reads this init file, thus +incorporating any changes that you might have made to it. + +

    + +
    +

    + +Next: , +Up: Readline Init File + +
    + +

    8.3.1 Readline Init File Syntax

    + +

    There are only a few basic constructs allowed in the +Readline init file. Blank lines are ignored. +Lines beginning with a `#' are comments. +Lines beginning with a `$' indicate conditional +constructs (see Conditional Init Constructs). Other lines +denote variable settings and key bindings. + +

    +
    Variable Settings
    You can modify the run-time behavior of Readline by +altering the values of variables in Readline +using the set command within the init file. +The syntax is simple: + + 
              set variable value
+
    +

    Here, for example, is how to +change from the default Emacs-like key binding to use +vi line editing commands: + + 

              set editing-mode vi
+
    +

    Variable names and values, where appropriate, are recognized without regard +to case. Unrecognized variable names are ignored. + +

    Boolean variables (those that can be set to on or off) are set to on if +the value is null or empty, on (case-insensitive), or 1. Any other +value results in the variable being set to off. + +

    The bind -V command lists the current Readline variable names +and values. See Bash Builtins. + +

    A great deal of run-time behavior is changeable with the following +variables. + +

    +

    +
    bell-style
    Controls what happens when Readline wants to ring the terminal bell. +If set to `none', Readline never rings the bell. If set to +`visible', Readline uses a visible bell if one is available. +If set to `audible' (the default), Readline attempts to ring +the terminal's bell. + +
    bind-tty-special-chars
    If set to `on', Readline attempts to bind the control characters +treated specially by the kernel's terminal driver to their Readline +equivalents. + +
    comment-begin
    The string to insert at the beginning of the line when the +insert-comment command is executed. The default value +is "#". + +
    completion-ignore-case
    If set to `on', Readline performs filename matching and completion +in a case-insensitive fashion. +The default value is `off'. + +
    completion-query-items
    The number of possible completions that determines when the user is +asked whether the list of possibilities should be displayed. +If the number of possible completions is greater than this value, +Readline will ask the user whether or not he wishes to view +them; otherwise, they are simply listed. +This variable must be set to an integer value greater than or equal to 0. +A negative value means Readline should never ask. +The default limit is 100. + +
    convert-meta
    If set to `on', Readline will convert characters with the +eighth bit set to an ascii key sequence by stripping the eighth +bit and prefixing an <ESC> character, converting them to a +meta-prefixed key sequence. The default value is `on'. + +
    disable-completion
    If set to `On', Readline will inhibit word completion. +Completion characters will be inserted into the line as if they had +been mapped to self-insert. The default is `off'. + +
    editing-mode
    The editing-mode variable controls which default set of +key bindings is used. By default, Readline starts up in Emacs editing +mode, where the keystrokes are most similar to Emacs. This variable can be +set to either `emacs' or `vi'. + +
    enable-keypad
    When set to `on', Readline will try to enable the application +keypad when it is called. Some systems need this to enable the +arrow keys. The default is `off'. + +
    expand-tilde
    If set to `on', tilde expansion is performed when Readline +attempts word completion. The default is `off'. + +
    history-preserve-point
    If set to `on', the history code attempts to place point at the +same location on each history line retrieved with previous-history +or next-history. The default is `off'. + +
    horizontal-scroll-mode
    This variable can be set to either `on' or `off'. Setting it +to `on' means that the text of the lines being edited will scroll +horizontally on a single screen line when they are longer than the width +of the screen, instead of wrapping onto a new screen line. By default, +this variable is set to `off'. + +
    input-meta
    If set to `on', Readline will enable eight-bit input (it +will not clear the eighth bit in the characters it reads), +regardless of what the terminal claims it can support. The +default value is `off'. The name meta-flag is a +synonym for this variable. + +
    isearch-terminators
    The string of characters that should terminate an incremental search without +subsequently executing the character as a command (see Searching). +If this variable has not been given a value, the characters <ESC> and +C-J will terminate an incremental search. + +
    keymap
    Sets Readline's idea of the current keymap for key binding commands. +Acceptable keymap names are +emacs, +emacs-standard, +emacs-meta, +emacs-ctlx, +vi, +vi-move, +vi-command, and +vi-insert. +vi is equivalent to vi-command; emacs is +equivalent to emacs-standard. The default value is emacs. +The value of the editing-mode variable also affects the +default keymap. + +
    mark-directories
    If set to `on', completed directory names have a slash +appended. The default is `on'. + +
    mark-modified-lines
    This variable, when set to `on', causes Readline to display an +asterisk (`*') at the start of history lines which have been modified. +This variable is `off' by default. + +
    mark-symlinked-directories
    If set to `on', completed names which are symbolic links +to directories have a slash appended (subject to the value of +mark-directories). +The default is `off'. + +
    match-hidden-files
    This variable, when set to `on', causes Readline to match files whose +names begin with a `.' (hidden files) when performing filename +completion, unless the leading `.' is +supplied by the user in the filename to be completed. +This variable is `on' by default. + +
    output-meta
    If set to `on', Readline will display characters with the +eighth bit set directly rather than as a meta-prefixed escape +sequence. The default is `off'. + +
    page-completions
    If set to `on', Readline uses an internal more-like pager +to display a screenful of possible completions at a time. +This variable is `on' by default. + +
    print-completions-horizontally
    If set to `on', Readline will display completions with matches +sorted horizontally in alphabetical order, rather than down the screen. +The default is `off'. + +
    show-all-if-ambiguous
    This alters the default behavior of the completion functions. If +set to `on', +words which have more than one possible completion cause the +matches to be listed immediately instead of ringing the bell. +The default value is `off'. + +
    show-all-if-unmodified
    This alters the default behavior of the completion functions in +a fashion similar to show-all-if-ambiguous. +If set to `on', +words which have more than one possible completion without any +possible partial completion (the possible completions don't share +a common prefix) cause the matches to be listed immediately instead +of ringing the bell. +The default value is `off'. + +
    visible-stats
    If set to `on', a character denoting a file's type +is appended to the filename when listing possible +completions. The default is `off'. + +
    + +
    Key Bindings
    The syntax for controlling key bindings in the init file is +simple. First you need to find the name of the command that you +want to change. The following sections contain tables of the command +name, the default keybinding, if any, and a short description of what +the command does. + +

    Once you know the name of the command, simply place on a line +in the init file the name of the key +you wish to bind the command to, a colon, and then the name of the +command. +There can be no space between the key name and the colon – that will be +interpreted as part of the key name. +The name of the key can be expressed in different ways, depending on +what you find most comfortable. + +

    In addition to command names, readline allows keys to be bound +to a string that is inserted when the key is pressed (a macro). + +

    The bind -p command displays Readline function names and +bindings in a format that can put directly into an initialization file. +See Bash Builtins. + +

    +
    keyname: function-name or macro
    keyname is the name of a key spelled out in English. For example: + 
                   Control-u: universal-argument
+               Meta-Rubout: backward-kill-word
+               Control-o: "> output"
+
    +

    In the above example, C-u is bound to the function +universal-argument, +M-DEL is bound to the function backward-kill-word, and +C-o is bound to run the macro +expressed on the right hand side (that is, to insert the text +`> output' into the line). + +

    A number of symbolic character names are recognized while +processing this key binding syntax: +DEL, +ESC, +ESCAPE, +LFD, +NEWLINE, +RET, +RETURN, +RUBOUT, +SPACE, +SPC, +and +TAB. + +

    "keyseq": function-name or macro
    keyseq differs from keyname above in that strings +denoting an entire key sequence can be specified, by placing +the key sequence in double quotes. Some gnu Emacs style key +escapes can be used, as in the following example, but the +special character names are not recognized. + + 
                   "\C-u": universal-argument
+               "\C-x\C-r": re-read-init-file
+               "\e[11~": "Function Key 1"
+
    +

    In the above example, C-u is again bound to the function +universal-argument (just as it was in the first example), +`C-x C-r' is bound to the function re-read-init-file, +and `<ESC> <[> <1> <1> <~>' is bound to insert +the text `Function Key 1'. + +

    + +

    The following gnu Emacs style escape sequences are available when +specifying key sequences: + +

    +
    \C-
    control prefix +
    \M-
    meta prefix +
    \e
    an escape character +
    \\
    backslash +
    \"
    <">, a double quotation mark +
    \'
    <'>, a single quote or apostrophe +
    + +

    In addition to the gnu Emacs style escape sequences, a second +set of backslash escapes is available: + +

    +
    \a
    alert (bell) +
    \b
    backspace +
    \d
    delete +
    \f
    form feed +
    \n
    newline +
    \r
    carriage return +
    \t
    horizontal tab +
    \v
    vertical tab +
    \nnn
    the eight-bit character whose value is the octal value nnn +(one to three digits) +
    \xHH
    the eight-bit character whose value is the hexadecimal value HH +(one or two hex digits) +
    + +

    When entering the text of a macro, single or double quotes must +be used to indicate a macro definition. +Unquoted text is assumed to be a function name. +In the macro body, the backslash escapes described above are expanded. +Backslash will quote any other character in the macro text, +including `"' and `''. +For example, the following binding will make `C-x \' +insert a single `\' into the line: + 

              "\C-x\\": "\\"
+
    +
    + +
    +

    + +Next: , +Previous: Readline Init File Syntax, +Up: Readline Init File + +
    + +

    8.3.2 Conditional Init Constructs

    + +

    Readline implements a facility similar in spirit to the conditional +compilation features of the C preprocessor which allows key +bindings and variable settings to be performed as the result +of tests. There are four parser directives used. + +

    +
    $if
    The $if construct allows bindings to be made based on the +editing mode, the terminal being used, or the application using +Readline. The text of the test extends to the end of the line; +no characters are required to isolate it. + +
    +
    mode
    The mode= form of the $if directive is used to test +whether Readline is in emacs or vi mode. +This may be used in conjunction +with the `set keymap' command, for instance, to set bindings in +the emacs-standard and emacs-ctlx keymaps only if +Readline is starting out in emacs mode. + +
    term
    The term= form may be used to include terminal-specific +key bindings, perhaps to bind the key sequences output by the +terminal's function keys. The word on the right side of the +`=' is tested against both the full name of the terminal and +the portion of the terminal name before the first `-'. This +allows sun to match both sun and sun-cmd, +for instance. + +
    application
    The application construct is used to include +application-specific settings. Each program using the Readline +library sets the application name, and you can test for +a particular value. +This could be used to bind key sequences to functions useful for +a specific program. For instance, the following command adds a +key sequence that quotes the current or previous word in Bash: + 
                   $if Bash
+               # Quote the current or previous word
+               "\C-xq": "\eb\"\ef\""
+               $endif
+
    +
    + +
    $endif
    This command, as seen in the previous example, terminates an +$if command. + +
    $else
    Commands in this branch of the $if directive are executed if +the test fails. + +
    $include
    This directive takes a single filename as an argument and reads commands +and bindings from that file. +For example, the following directive reads from /etc/inputrc: + 
              $include /etc/inputrc
+
    +
    + +
    +

    + +Previous: Conditional Init Constructs, +Up: Readline Init File + +
    + +

    8.3.3 Sample Init File

    + +

    Here is an example of an inputrc file. This illustrates key +binding, variable assignment, and conditional syntax. + +

         
+     # This file controls the behaviour of line input editing for
+     # programs that use the GNU Readline library.  Existing
+     # programs include FTP, Bash, and GDB.
+     #
+     # You can re-read the inputrc file with C-x C-r.
+     # Lines beginning with '#' are comments.
+     #
+     # First, include any systemwide bindings and variable
+     # assignments from /etc/Inputrc
+     $include /etc/Inputrc
+     
+     #
+     # Set various bindings for emacs mode.
+     
+     set editing-mode emacs
+     
+     $if mode=emacs
+     
+     Meta-Control-h:	backward-kill-word	Text after the function name is ignored
+     
+     #
+     # Arrow keys in keypad mode
+     #
+     #"\M-OD":        backward-char
+     #"\M-OC":        forward-char
+     #"\M-OA":        previous-history
+     #"\M-OB":        next-history
+     #
+     # Arrow keys in ANSI mode
+     #
+     "\M-[D":        backward-char
+     "\M-[C":        forward-char
+     "\M-[A":        previous-history
+     "\M-[B":        next-history
+     #
+     # Arrow keys in 8 bit keypad mode
+     #
+     #"\M-\C-OD":       backward-char
+     #"\M-\C-OC":       forward-char
+     #"\M-\C-OA":       previous-history
+     #"\M-\C-OB":       next-history
+     #
+     # Arrow keys in 8 bit ANSI mode
+     #
+     #"\M-\C-[D":       backward-char
+     #"\M-\C-[C":       forward-char
+     #"\M-\C-[A":       previous-history
+     #"\M-\C-[B":       next-history
+     
+     C-q: quoted-insert
+     
+     $endif
+     
+     # An old-style binding.  This happens to be the default.
+     TAB: complete
+     
+     # Macros that are convenient for shell interaction
+     $if Bash
+     # edit the path
+     "\C-xp": "PATH=${PATH}\e\C-e\C-a\ef\C-f"
+     # prepare to type a quoted word --
+     # insert open and close double quotes
+     # and move to just after the open quote
+     "\C-x\"": "\"\"\C-b"
+     # insert a backslash (testing backslash escapes
+     # in sequences and macros)
+     "\C-x\\": "\\"
+     # Quote the current or previous word
+     "\C-xq": "\eb\"\ef\""
+     # Add a binding to refresh the line, which is unbound
+     "\C-xr": redraw-current-line
+     # Edit variable on current line.
+     "\M-\C-v": "\C-a\C-k$\C-y\M-\C-e\C-a\C-y="
+     $endif
+     
+     # use a visible bell if one is available
+     set bell-style visible
+     
+     # don't strip characters to 7 bits when reading
+     set input-meta on
+     
+     # allow iso-latin1 characters to be inserted rather
+     # than converted to prefix-meta sequences
+     set convert-meta off
+     
+     # display characters with the eighth bit set directly
+     # rather than as meta-prefixed characters
+     set output-meta on
+     
+     # if there are more than 150 possible completions for
+     # a word, ask the user if he wants to see all of them
+     set completion-query-items 150
+     
+     # For FTP
+     $if Ftp
+     "\C-xg": "get \M-?"
+     "\C-xt": "put \M-?"
+     "\M-.": yank-last-arg
+     $endif
+
    +
    +

    + +Next: , +Previous: Readline Init File, +Up: Command Line Editing + +
    + +

    8.4 Bindable Readline Commands

    + + + +

    This section describes Readline commands that may be bound to key +sequences. +You can list your key bindings by executing +bind -P or, for a more terse format, suitable for an +inputrc file, bind -p. (See Bash Builtins.) +Command names without an accompanying key sequence are unbound by default. + +

    In the following descriptions, point refers to the current cursor +position, and mark refers to a cursor position saved by the +set-mark command. +The text between the point and mark is referred to as the region. + +

    +

    + +Next: , +Up: Bindable Readline Commands + +
    + +

    8.4.1 Commands For Moving

    + +
    +
    beginning-of-line (C-a)
    Move to the start of the current line. + +
    end-of-line (C-e)
    Move to the end of the line. + +
    forward-char (C-f)
    Move forward a character. + +
    backward-char (C-b)
    Move back a character. + +
    forward-word (M-f)
    Move forward to the end of the next word. Words are composed of +letters and digits. + +
    backward-word (M-b)
    Move back to the start of the current or previous word. Words are +composed of letters and digits. + +
    clear-screen (C-l)
    Clear the screen and redraw the current line, +leaving the current line at the top of the screen. + +
    redraw-current-line ()
    Refresh the current line. By default, this is unbound. + +
    + +
    +

    + +Next: , +Previous: Commands For Moving, +Up: Bindable Readline Commands + +
    + +

    8.4.2 Commands For Manipulating The History

    + +
    +
    accept-line (Newline or Return)
    Accept the line regardless of where the cursor is. +If this line is +non-empty, add it to the history list according to the setting of +the HISTCONTROL and HISTIGNORE variables. +If this line is a modified history line, then restore the history line +to its original state. + +
    previous-history (C-p)
    Move `back' through the history list, fetching the previous command. + +
    next-history (C-n)
    Move `forward' through the history list, fetching the next command. + +
    beginning-of-history (M-<)
    Move to the first line in the history. + +
    end-of-history (M->)
    Move to the end of the input history, i.e., the line currently +being entered. + +
    reverse-search-history (C-r)
    Search backward starting at the current line and moving `up' through +the history as necessary. This is an incremental search. + +
    forward-search-history (C-s)
    Search forward starting at the current line and moving `down' through +the the history as necessary. This is an incremental search. + +
    non-incremental-reverse-search-history (M-p)
    Search backward starting at the current line and moving `up' +through the history as necessary using a non-incremental search +for a string supplied by the user. + +
    non-incremental-forward-search-history (M-n)
    Search forward starting at the current line and moving `down' +through the the history as necessary using a non-incremental search +for a string supplied by the user. + +
    history-search-forward ()
    Search forward through the history for the string of characters +between the start of the current line and the point. +This is a non-incremental search. +By default, this command is unbound. + +
    history-search-backward ()
    Search backward through the history for the string of characters +between the start of the current line and the point. This +is a non-incremental search. By default, this command is unbound. + +
    yank-nth-arg (M-C-y)
    Insert the first argument to the previous command (usually +the second word on the previous line) at point. +With an argument n, +insert the nth word from the previous command (the words +in the previous command begin with word 0). A negative argument +inserts the nth word from the end of the previous command. +Once the argument n is computed, the argument is extracted +as if the `!n' history expansion had been specified. + +
    yank-last-arg (M-. or M-_)
    Insert last argument to the previous command (the last word of the +previous history entry). With an +argument, behave exactly like yank-nth-arg. +Successive calls to yank-last-arg move back through the history +list, inserting the last argument of each line in turn. +The history expansion facilities are used to extract the last argument, +as if the `!$' history expansion had been specified. + +
    + +
    +

    + +Next: , +Previous: Commands For History, +Up: Bindable Readline Commands + +
    + +

    8.4.3 Commands For Changing Text

    + +
    +
    delete-char (C-d)
    Delete the character at point. If point is at the +beginning of the line, there are no characters in the line, and +the last character typed was not bound to delete-char, then +return eof. + +
    backward-delete-char (Rubout)
    Delete the character behind the cursor. A numeric argument means +to kill the characters instead of deleting them. + +
    forward-backward-delete-char ()
    Delete the character under the cursor, unless the cursor is at the +end of the line, in which case the character behind the cursor is +deleted. By default, this is not bound to a key. + +
    quoted-insert (C-q or C-v)
    Add the next character typed to the line verbatim. This is +how to insert key sequences like C-q, for example. + +
    self-insert (a, b, A, 1, !, ...)
    Insert yourself. + +
    transpose-chars (C-t)
    Drag the character before the cursor forward over +the character at the cursor, moving the +cursor forward as well. If the insertion point +is at the end of the line, then this +transposes the last two characters of the line. +Negative arguments have no effect. + +
    transpose-words (M-t)
    Drag the word before point past the word after point, +moving point past that word as well. +If the insertion point is at the end of the line, this transposes +the last two words on the line. + +
    upcase-word (M-u)
    Uppercase the current (or following) word. With a negative argument, +uppercase the previous word, but do not move the cursor. + +
    downcase-word (M-l)
    Lowercase the current (or following) word. With a negative argument, +lowercase the previous word, but do not move the cursor. + +
    capitalize-word (M-c)
    Capitalize the current (or following) word. With a negative argument, +capitalize the previous word, but do not move the cursor. + +
    overwrite-mode ()
    Toggle overwrite mode. With an explicit positive numeric argument, +switches to overwrite mode. With an explicit non-positive numeric +argument, switches to insert mode. This command affects only +emacs mode; vi mode does overwrite differently. +Each call to readline() starts in insert mode. + +

    In overwrite mode, characters bound to self-insert replace +the text at point rather than pushing the text to the right. +Characters bound to backward-delete-char replace the character +before point with a space. + +

    By default, this command is unbound. + +

    + +
    +

    + +Next: , +Previous: Commands For Text, +Up: Bindable Readline Commands + +
    + +

    8.4.4 Killing And Yanking

    + +
    +
    kill-line (C-k)
    Kill the text from point to the end of the line. + +
    backward-kill-line (C-x Rubout)
    Kill backward to the beginning of the line. + +
    unix-line-discard (C-u)
    Kill backward from the cursor to the beginning of the current line. + +
    kill-whole-line ()
    Kill all characters on the current line, no matter where point is. +By default, this is unbound. + +
    kill-word (M-d)
    Kill from point to the end of the current word, or if between +words, to the end of the next word. +Word boundaries are the same as forward-word. + +
    backward-kill-word (M-<DEL>)
    Kill the word behind point. +Word boundaries are the same as backward-word. + +
    unix-word-rubout (C-w)
    Kill the word behind point, using white space as a word boundary. +The killed text is saved on the kill-ring. + +
    unix-filename-rubout ()
    Kill the word behind point, using white space and the slash character +as the word boundaries. +The killed text is saved on the kill-ring. + +
    delete-horizontal-space ()
    Delete all spaces and tabs around point. By default, this is unbound. + +
    kill-region ()
    Kill the text in the current region. +By default, this command is unbound. + +
    copy-region-as-kill ()
    Copy the text in the region to the kill buffer, so it can be yanked +right away. By default, this command is unbound. + +
    copy-backward-word ()
    Copy the word before point to the kill buffer. +The word boundaries are the same as backward-word. +By default, this command is unbound. + +
    copy-forward-word ()
    Copy the word following point to the kill buffer. +The word boundaries are the same as forward-word. +By default, this command is unbound. + +
    yank (C-y)
    Yank the top of the kill ring into the buffer at point. + +
    yank-pop (M-y)
    Rotate the kill-ring, and yank the new top. You can only do this if +the prior command is yank or yank-pop. +
    + +
    +

    + +Next: , +Previous: Commands For Killing, +Up: Bindable Readline Commands + +
    + +

    8.4.5 Specifying Numeric Arguments

    + +
    +
    digit-argument (M-0, M-1, ... M--)
    Add this digit to the argument already accumulating, or start a new +argument. M-- starts a negative argument. + +
    universal-argument ()
    This is another way to specify an argument. +If this command is followed by one or more digits, optionally with a +leading minus sign, those digits define the argument. +If the command is followed by digits, executing universal-argument +again ends the numeric argument, but is otherwise ignored. +As a special case, if this command is immediately followed by a +character that is neither a digit or minus sign, the argument count +for the next command is multiplied by four. +The argument count is initially one, so executing this function the +first time makes the argument count four, a second time makes the +argument count sixteen, and so on. +By default, this is not bound to a key. +
    + +
    +

    + +Next: , +Previous: Numeric Arguments, +Up: Bindable Readline Commands + +
    + +

    8.4.6 Letting Readline Type For You

    + +
    +
    complete (<TAB>)
    Attempt to perform completion on the text before point. +The actual completion performed is application-specific. +Bash attempts completion treating the text as a variable (if the +text begins with `$'), username (if the text begins with +`~'), hostname (if the text begins with `@'), or +command (including aliases and functions) in turn. If none +of these produces a match, filename completion is attempted. + +
    possible-completions (M-?)
    List the possible completions of the text before point. + +
    insert-completions (M-*)
    Insert all completions of the text before point that would have +been generated by possible-completions. + +
    menu-complete ()
    Similar to complete, but replaces the word to be completed +with a single match from the list of possible completions. +Repeated execution of menu-complete steps through the list +of possible completions, inserting each match in turn. +At the end of the list of completions, the bell is rung +(subject to the setting of bell-style) +and the original text is restored. +An argument of n moves n positions forward in the list +of matches; a negative argument may be used to move backward +through the list. +This command is intended to be bound to <TAB>, but is unbound +by default. + +
    delete-char-or-list ()
    Deletes the character under the cursor if not at the beginning or +end of the line (like delete-char). +If at the end of the line, behaves identically to +possible-completions. +This command is unbound by default. + +
    complete-filename (M-/)
    Attempt filename completion on the text before point. + +
    possible-filename-completions (C-x /)
    List the possible completions of the text before point, +treating it as a filename. + +
    complete-username (M-~)
    Attempt completion on the text before point, treating +it as a username. + +
    possible-username-completions (C-x ~)
    List the possible completions of the text before point, +treating it as a username. + +
    complete-variable (M-$)
    Attempt completion on the text before point, treating +it as a shell variable. + +
    possible-variable-completions (C-x $)
    List the possible completions of the text before point, +treating it as a shell variable. + +
    complete-hostname (M-@)
    Attempt completion on the text before point, treating +it as a hostname. + +
    possible-hostname-completions (C-x @)
    List the possible completions of the text before point, +treating it as a hostname. + +
    complete-command (M-!)
    Attempt completion on the text before point, treating +it as a command name. Command completion attempts to +match the text against aliases, reserved words, shell +functions, shell builtins, and finally executable filenames, +in that order. + +
    possible-command-completions (C-x !)
    List the possible completions of the text before point, +treating it as a command name. + +
    dynamic-complete-history (M-<TAB>)
    Attempt completion on the text before point, comparing +the text against lines from the history list for possible +completion matches. + +
    complete-into-braces (M-{)
    Perform filename completion and insert the list of possible completions +enclosed within braces so the list is available to the shell +(see Brace Expansion). + +
    + +
    +

    + +Next: , +Previous: Commands For Completion, +Up: Bindable Readline Commands + +
    + +

    8.4.7 Keyboard Macros

    + +
    +
    start-kbd-macro (C-x ()
    Begin saving the characters typed into the current keyboard macro. + +
    end-kbd-macro (C-x ))
    Stop saving the characters typed into the current keyboard macro +and save the definition. + +
    call-last-kbd-macro (C-x e)
    Re-execute the last keyboard macro defined, by making the characters +in the macro appear as if typed at the keyboard. + +
    + +
    +

    + +Previous: Keyboard Macros, +Up: Bindable Readline Commands + +
    + +

    8.4.8 Some Miscellaneous Commands

    + +
    +
    re-read-init-file (C-x C-r)
    Read in the contents of the inputrc file, and incorporate +any bindings or variable assignments found there. + +
    abort (C-g)
    Abort the current editing command and +ring the terminal's bell (subject to the setting of +bell-style). + +
    do-uppercase-version (M-a, M-b, M-x, ...)
    If the metafied character x is lowercase, run the command +that is bound to the corresponding uppercase character. + +
    prefix-meta (<ESC>)
    Metafy the next character typed. This is for keyboards +without a meta key. Typing `<ESC> f' is equivalent to typing +M-f. + +
    undo (C-_ or C-x C-u)
    Incremental undo, separately remembered for each line. + +
    revert-line (M-r)
    Undo all changes made to this line. This is like executing the undo +command enough times to get back to the beginning. + +
    tilde-expand (M-&)
    Perform tilde expansion on the current word. + +
    set-mark (C-@)
    Set the mark to the point. If a +numeric argument is supplied, the mark is set to that position. + +
    exchange-point-and-mark (C-x C-x)
    Swap the point with the mark. The current cursor position is set to +the saved position, and the old cursor position is saved as the mark. + +
    character-search (C-])
    A character is read and point is moved to the next occurrence of that +character. A negative count searches for previous occurrences. + +
    character-search-backward (M-C-])
    A character is read and point is moved to the previous occurrence +of that character. A negative count searches for subsequent +occurrences. + +
    insert-comment (M-#)
    Without a numeric argument, the value of the comment-begin +variable is inserted at the beginning of the current line. +If a numeric argument is supplied, this command acts as a toggle: if +the characters at the beginning of the line do not match the value +of comment-begin, the value is inserted, otherwise +the characters in comment-begin are deleted from the beginning of +the line. +In either case, the line is accepted as if a newline had been typed. +The default value of comment-begin causes this command +to make the current line a shell comment. +If a numeric argument causes the comment character to be removed, the line +will be executed by the shell. + +
    dump-functions ()
    Print all of the functions and their key bindings to the +Readline output stream. If a numeric argument is supplied, +the output is formatted in such a way that it can be made part +of an inputrc file. This command is unbound by default. + +
    dump-variables ()
    Print all of the settable variables and their values to the +Readline output stream. If a numeric argument is supplied, +the output is formatted in such a way that it can be made part +of an inputrc file. This command is unbound by default. + +
    dump-macros ()
    Print all of the Readline key sequences bound to macros and the +strings they output. If a numeric argument is supplied, +the output is formatted in such a way that it can be made part +of an inputrc file. This command is unbound by default. + +
    glob-complete-word (M-g)
    The word before point is treated as a pattern for pathname expansion, +with an asterisk implicitly appended. This pattern is used to +generate a list of matching file names for possible completions. + +
    glob-expand-word (C-x *)
    The word before point is treated as a pattern for pathname expansion, +and the list of matching file names is inserted, replacing the word. +If a numeric argument is supplied, a `*' is appended before +pathname expansion. + +
    glob-list-expansions (C-x g)
    The list of expansions that would have been generated by +glob-expand-word is displayed, and the line is redrawn. +If a numeric argument is supplied, a `*' is appended before +pathname expansion. + +
    display-shell-version (C-x C-v)
    Display version information about the current instance of Bash. + +
    shell-expand-line (M-C-e)
    Expand the line as the shell does. +This performs alias and history expansion as well as all of the shell +word expansions (see Shell Expansions). + +
    history-expand-line (M-^)
    Perform history expansion on the current line. + +
    magic-space ()
    Perform history expansion on the current line and insert a space +(see History Interaction). + +
    alias-expand-line ()
    Perform alias expansion on the current line (see Aliases). + +
    history-and-alias-expand-line ()
    Perform history and alias expansion on the current line. + +
    insert-last-argument (M-. or M-_)
    A synonym for yank-last-arg. + +
    operate-and-get-next (C-o)
    Accept the current line for execution and fetch the next line +relative to the current line from the history for editing. Any +argument is ignored. + +
    edit-and-execute-command (C-xC-e)
    Invoke an editor on the current command line, and execute the result as shell +commands. +Bash attempts to invoke +$VISUAL, $EDITOR, and emacs +as the editor, in that order. + +
    + +
    +

    + +Next: , +Previous: Bindable Readline Commands, +Up: Command Line Editing + +
    + +

    8.5 Readline vi Mode

    + +

    While the Readline library does not have a full set of vi +editing functions, it does contain enough to allow simple editing +of the line. The Readline vi mode behaves as specified in +the posix 1003.2 standard. + +

    In order to switch interactively between emacs and vi +editing modes, use the `set -o emacs' and `set -o vi' +commands (see The Set Builtin). +The Readline default is emacs mode. + +

    When you enter a line in vi mode, you are already placed in +`insertion' mode, as if you had typed an `i'. Pressing <ESC> +switches you into `command' mode, where you can edit the text of the +line with the standard vi movement keys, move to previous +history lines with `k' and subsequent lines with `j', and +so forth. + +

    +

    + +Next: , +Previous: Readline vi Mode, +Up: Command Line Editing + +
    + +

    8.6 Programmable Completion

    + +

    +When word completion is attempted for an argument to a command for +which a completion specification (a compspec) has been defined +using the complete builtin (see Programmable Completion Builtins), +the programmable completion facilities are invoked. + +

    First, the command name is identified. +If a compspec has been defined for that command, the +compspec is used to generate the list of possible completions for the word. +If the command word is a full pathname, a compspec for the full +pathname is searched for first. +If no compspec is found for the full pathname, an attempt is made to +find a compspec for the portion following the final slash. + +

    Once a compspec has been found, it is used to generate the list of +matching words. +If a compspec is not found, the default Bash completion +described above (see Commands For Completion) is performed. + +

    First, the actions specified by the compspec are used. +Only matches which are prefixed by the word being completed are +returned. +When the -f or -d option is used for filename or +directory name completion, the shell variable FIGNORE is +used to filter the matches. +See Bash Variables, for a description of FIGNORE. + +

    Any completions specified by a filename expansion pattern to the +-G option are generated next. +The words generated by the pattern need not match the word being completed. +The GLOBIGNORE shell variable is not used to filter the matches, +but the FIGNORE shell variable is used. + +

    Next, the string specified as the argument to the -W option +is considered. +The string is first split using the characters in the IFS +special variable as delimiters. +Shell quoting is honored. +Each word is then expanded using +brace expansion, tilde expansion, parameter and variable expansion, +command substitution, and arithmetic expansion, +as described above (see Shell Expansions). +The results are split using the rules described above +(see Word Splitting). +The results of the expansion are prefix-matched against the word being +completed, and the matching words become the possible completions. + +

    After these matches have been generated, any shell function or command +specified with the -F and -C options is invoked. +When the command or function is invoked, the COMP_LINE, +COMP_POINT, COMP_KEY, and COMP_TYPE variables are +assigned values as described above (see Bash Variables). +If a shell function is being invoked, the COMP_WORDS and +COMP_CWORD variables are also set. +When the function or command is invoked, the first argument is the +name of the command whose arguments are being completed, the +second argument is the word being completed, and the third argument +is the word preceding the word being completed on the current command line. +No filtering of the generated completions against the word being completed +is performed; the function or command has complete freedom in generating +the matches. + +

    Any function specified with -F is invoked first. +The function may use any of the shell facilities, including the +compgen builtin described below +(see Programmable Completion Builtins), to generate the matches. +It must put the possible completions in the COMPREPLY array +variable. + +

    Next, any command specified with the -C option is invoked +in an environment equivalent to command substitution. +It should print a list of completions, one per line, to +the standard output. +Backslash may be used to escape a newline, if necessary. + +

    After all of the possible completions are generated, any filter +specified with the -X option is applied to the list. +The filter is a pattern as used for pathname expansion; a `&' +in the pattern is replaced with the text of the word being completed. +A literal `&' may be escaped with a backslash; the backslash +is removed before attempting a match. +Any completion that matches the pattern will be removed from the list. +A leading `!' negates the pattern; in this case any completion +not matching the pattern will be removed. + +

    Finally, any prefix and suffix specified with the -P and -S +options are added to each member of the completion list, and the result is +returned to the Readline completion code as the list of possible +completions. + +

    If the previously-applied actions do not generate any matches, and the +-o dirnames option was supplied to complete when the +compspec was defined, directory name completion is attempted. + +

    If the -o plusdirs option was supplied to complete when +the compspec was defined, directory name completion is attempted and any +matches are added to the results of the other actions. + +

    By default, if a compspec is found, whatever it generates is returned to +the completion code as the full set of possible completions. +The default Bash completions are not attempted, and the Readline default +of filename completion is disabled. +If the -o bashdefault option was supplied to complete when +the compspec was defined, the default Bash completions are attempted +if the compspec generates no matches. +If the -o default option was supplied to complete when the +compspec was defined, Readline's default completion will be performed +if the compspec (and, if attempted, the default Bash completions) +generate no matches. + +

    When a compspec indicates that directory name completion is desired, +the programmable completion functions force Readline to append a slash +to completed names which are symbolic links to directories, subject to +the value of the mark-directories Readline variable, regardless +of the setting of the mark-symlinked-directories Readline variable. + +

    +

    + +Previous: Programmable Completion, +Up: Command Line Editing + +
    + +

    8.7 Programmable Completion Builtins

    + +

    +Two builtin commands are available to manipulate the programmable completion +facilities. + +

    +
    compgen
    + 
              compgen [option] [word]
+
    +

    Generate possible completion matches for word according to +the options, which may be any option accepted by the +complete +builtin with the exception of -p and -r, and write +the matches to the standard output. +When using the -F or -C options, the various shell variables +set by the programmable completion facilities, while available, will not +have useful values. + +

    The matches will be generated in the same way as if the programmable +completion code had generated them directly from a completion specification +with the same flags. +If word is specified, only those completions matching word +will be displayed. + +

    The return value is true unless an invalid option is supplied, or no +matches were generated. + +

    complete
    + 
              complete [-abcdefgjksuv] [-o comp-option] [-A action] [-G globpat] [-W wordlist]
+          [-F function] [-C command] [-X filterpat]
+          [-P prefix] [-S suffix] name [name ...]
+          complete -pr [name ...]
+
    +

    Specify how arguments to each name should be completed. +If the -p option is supplied, or if no options are supplied, existing +completion specifications are printed in a way that allows them to be +reused as input. +The -r option removes a completion specification for +each name, or, if no names are supplied, all +completion specifications. + +

    The process of applying these completion specifications when word completion +is attempted is described above (see Programmable Completion). + +

    Other options, if specified, have the following meanings. +The arguments to the -G, -W, and -X options +(and, if necessary, the -P and -S options) +should be quoted to protect them from expansion before the +complete builtin is invoked. + +

    +
    -o comp-option
    The comp-option controls several aspects of the compspec's behavior +beyond the simple generation of completions. +comp-option may be one of: + +
    +
    bashdefault
    Perform the rest of the default Bash completions if the compspec +generates no matches. + +
    default
    Use Readline's default filename completion if the compspec generates +no matches. + +
    dirnames
    Perform directory name completion if the compspec generates no matches. + +
    filenames
    Tell Readline that the compspec generates filenames, so it can perform any +filename-specific processing (like adding a slash to directory names or +suppressing trailing spaces). This option is intended to be used with +shell functions specified with -F. + +
    nospace
    Tell Readline not to append a space (the default) to words completed at +the end of the line. + +
    plusdirs
    After any matches defined by the compspec are generated, +directory name completion is attempted and any +matches are added to the results of the other actions. + +
    + +
    -A action
    The action may be one of the following to generate a list of possible +completions: + +
    +
    alias
    Alias names. May also be specified as -a. + +
    arrayvar
    Array variable names. + +
    binding
    Readline key binding names (see Bindable Readline Commands). + +
    builtin
    Names of shell builtin commands. May also be specified as -b. + +
    command
    Command names. May also be specified as -c. + +
    directory
    Directory names. May also be specified as -d. + +
    disabled
    Names of disabled shell builtins. + +
    enabled
    Names of enabled shell builtins. + +
    export
    Names of exported shell variables. May also be specified as -e. + +
    file
    File names. May also be specified as -f. + +
    function
    Names of shell functions. + +
    group
    Group names. May also be specified as -g. + +
    helptopic
    Help topics as accepted by the help builtin (see Bash Builtins). + +
    hostname
    Hostnames, as taken from the file specified by the +HOSTFILE shell variable (see Bash Variables). + +
    job
    Job names, if job control is active. May also be specified as -j. + +
    keyword
    Shell reserved words. May also be specified as -k. + +
    running
    Names of running jobs, if job control is active. + +
    service
    Service names. May also be specified as -s. + +
    setopt
    Valid arguments for the -o option to the set builtin +(see The Set Builtin). + +
    shopt
    Shell option names as accepted by the shopt builtin +(see Bash Builtins). + +
    signal
    Signal names. + +
    stopped
    Names of stopped jobs, if job control is active. + +
    user
    User names. May also be specified as -u. + +
    variable
    Names of all shell variables. May also be specified as -v. +
    + +
    -G globpat
    The filename expansion pattern globpat is expanded to generate +the possible completions. + +
    -W wordlist
    The wordlist is split using the characters in the +IFS special variable as delimiters, and each resultant word +is expanded. +The possible completions are the members of the resultant list which +match the word being completed. + +
    -C command
    command is executed in a subshell environment, and its output is +used as the possible completions. + +
    -F function
    The shell function function is executed in the current shell +environment. +When it finishes, the possible completions are retrieved from the value +of the COMPREPLY array variable. + +
    -X filterpat
    filterpat is a pattern as used for filename expansion. +It is applied to the list of possible completions generated by the +preceding options and arguments, and each completion matching +filterpat is removed from the list. +A leading `!' in filterpat negates the pattern; in this +case, any completion not matching filterpat is removed. + +
    -P prefix
    prefix is added at the beginning of each possible completion +after all other options have been applied. + +
    -S suffix
    suffix is appended to each possible completion +after all other options have been applied. +
    + +

    The return value is true unless an invalid option is supplied, an option +other than -p or -r is supplied without a name +argument, an attempt is made to remove a completion specification for +a name for which no specification exists, or +an error occurs adding a completion specification. + +

    + + +
    +

    + +Next: , +Previous: Job Control, +Up: Top + +
    + +

    9 Using History Interactively

    + +

    This chapter describes how to use the gnu History Library +interactively, from a user's standpoint. +It should be considered a user's guide. +For information on using the gnu History Library in other programs, +see the gnu Readline Library Manual. + +

    + +
    +

    + +Next: , +Up: Using History Interactively + +
    + +

    9.1 Bash History Facilities

    + +

    +When the -o history option to the set builtin +is enabled (see The Set Builtin), +the shell provides access to the command history, +the list of commands previously typed. +The value of the HISTSIZE shell variable is used as the +number of commands to save in a history list. +The text of the last $HISTSIZE +commands (default 500) is saved. +The shell stores each command in the history list prior to +parameter and variable expansion +but after history expansion is performed, subject to the +values of the shell variables +HISTIGNORE and HISTCONTROL. + +

    When the shell starts up, the history is initialized from the +file named by the HISTFILE variable (default ~/.bash_history). +The file named by the value of HISTFILE is truncated, if +necessary, to contain no more than the number of lines specified by +the value of the HISTFILESIZE variable. +When an interactive shell exits, the last +$HISTSIZE lines are copied from the history list to the file +named by $HISTFILE. +If the histappend shell option is set (see Bash Builtins), +the lines are appended to the history file, +otherwise the history file is overwritten. +If HISTFILE +is unset, or if the history file is unwritable, the history is +not saved. After saving the history, the history file is truncated +to contain no more than $HISTFILESIZE +lines. If HISTFILESIZE is not set, no truncation is performed. + +

    If the HISTTIMEFORMAT is set, the time stamp information +associated with each history entry is written to the history file. + +

    The builtin command fc may be used to list or edit and re-execute +a portion of the history list. +The history builtin may be used to display or modify the history +list and manipulate the history file. +When using command-line editing, search commands +are available in each editing mode that provide access to the +history list (see Commands For History). + +

    The shell allows control over which commands are saved on the history +list. The HISTCONTROL and HISTIGNORE +variables may be set to cause the shell to save only a subset of the +commands entered. +The cmdhist +shell option, if enabled, causes the shell to attempt to save each +line of a multi-line command in the same history entry, adding +semicolons where necessary to preserve syntactic correctness. +The lithist +shell option causes the shell to save the command with embedded newlines +instead of semicolons. +The shopt builtin is used to set these options. +See Bash Builtins, for a description of shopt. + +

    +

    + +Next: , +Previous: Bash History Facilities, +Up: Using History Interactively + +
    + +

    9.2 Bash History Builtins

    + +

    +Bash provides two builtin commands which manipulate the +history list and history file. + +

    +
    fc
    + 
              fc [-e ename] [-lnr] [first] [last]
+          fc -s [pat=rep] [command]
+
    +

    Fix Command. In the first form, a range of commands from first to +last is selected from the history list. Both first and +last may be specified as a string (to locate the most recent +command beginning with that string) or as a number (an index into the +history list, where a negative number is used as an offset from the +current command number). If last is not specified it is set to +first. If first is not specified it is set to the previous +command for editing and −16 for listing. If the -l flag is +given, the commands are listed on standard output. The -n flag +suppresses the command numbers when listing. The -r flag +reverses the order of the listing. Otherwise, the editor given by +ename is invoked on a file containing those commands. If +ename is not given, the value of the following variable expansion +is used: ${FCEDIT:-${EDITOR:-vi}}. This says to use the +value of the FCEDIT variable if set, or the value of the +EDITOR variable if that is set, or vi if neither is set. +When editing is complete, the edited commands are echoed and executed. + +

    In the second form, command is re-executed after each instance +of pat in the selected command is replaced by rep. + +

    A useful alias to use with the fc command is r='fc -s', so +that typing `r cc' runs the last command beginning with cc +and typing `r' re-executes the last command (see Aliases). + +

    history
    + 
              history [n]
+          history -c
+          history -d offset
+          history [-anrw] [filename]
+          history -ps arg
+
    +

    With no options, display the history list with line numbers. +Lines prefixed with a `*' have been modified. +An argument of n lists only the last n lines. +If the shell variable HISTTIMEFORMAT is set and not null, +it is used as a format string for strftime to display +the time stamp associated with each displayed history entry. +No intervening blank is printed between the formatted time stamp +and the history line. + +

    Options, if supplied, have the following meanings: + +

    +
    -c
    Clear the history list. This may be combined +with the other options to replace the history list completely. + +
    -d offset
    Delete the history entry at position offset. +offset should be specified as it appears when the history is +displayed. + +
    -a
    Append the new +history lines (history lines entered since the beginning of the +current Bash session) to the history file. + +
    -n
    Append the history lines not already read from the history file +to the current history list. These are lines appended to the history +file since the beginning of the current Bash session. + +
    -r
    Read the current history file and append its contents to +the history list. + +
    -w
    Write out the current history to the history file. + +
    -p
    Perform history substitution on the args and display the result +on the standard output, without storing the results in the history list. + +
    -s
    The args are added to the end of +the history list as a single entry. + +
    + +

    When any of the -w, -r, -a, or -n options is +used, if filename +is given, then it is used as the history file. If not, then +the value of the HISTFILE variable is used. + +

    + +
    +

    + +Previous: Bash History Builtins, +Up: Using History Interactively + +
    + +

    9.3 History Expansion

    + +

    +The History library provides a history expansion feature that is similar +to the history expansion provided by csh. This section +describes the syntax used to manipulate the history information. + +

    History expansions introduce words from the history list into +the input stream, making it easy to repeat commands, insert the +arguments to a previous command into the current input line, or +fix errors in previous commands quickly. + +

    History expansion takes place in two parts. The first is to determine +which line from the history list should be used during substitution. +The second is to select portions of that line for inclusion into the +current one. The line selected from the history is called the +event, and the portions of that line that are acted upon are +called words. Various modifiers are available to manipulate +the selected words. The line is broken into words in the same fashion +that Bash does, so that several words +surrounded by quotes are considered one word. +History expansions are introduced by the appearance of the +history expansion character, which is `!' by default. +Only `\' and `'' may be used to escape the history expansion +character. + +

    Several shell options settable with the shopt +builtin (see Bash Builtins) may be used to tailor +the behavior of history expansion. If the +histverify shell option is enabled, and Readline +is being used, history substitutions are not immediately passed to +the shell parser. +Instead, the expanded line is reloaded into the Readline +editing buffer for further modification. +If Readline is being used, and the histreedit +shell option is enabled, a failed history expansion will be +reloaded into the Readline editing buffer for correction. +The -p option to the history builtin command +may be used to see what a history expansion will do before using it. +The -s option to the history builtin may be used to +add commands to the end of the history list without actually executing +them, so that they are available for subsequent recall. +This is most useful in conjunction with Readline. + +

    The shell allows control of the various characters used by the +history expansion mechanism with the histchars variable. + +

    + +
    +

    + +Next: , +Up: History Interaction + +
    + +

    9.3.1 Event Designators

    + +

    +An event designator is a reference to a command line entry in the +history list. + +

    +
    !
    Start a history substitution, except when followed by a space, tab, +the end of the line, `=' or `(' (when the +extglob shell option is enabled using the shopt builtin). + +
    !n
    Refer to command line n. + +
    !-n
    Refer to the command n lines back. + +
    !!
    Refer to the previous command. This is a synonym for `!-1'. + +
    !string
    Refer to the most recent command starting with string. + +
    !?string[?]
    Refer to the most recent command containing string. The trailing +`?' may be omitted if the string is followed immediately by +a newline. + +
    ^string1^string2^
    Quick Substitution. Repeat the last command, replacing string1 +with string2. Equivalent to +!!:s/string1/string2/. + +
    !#
    The entire command line typed so far. + +
    + +
    +

    + +Next: , +Previous: Event Designators, +Up: History Interaction + +
    + +

    9.3.2 Word Designators

    + +

    Word designators are used to select desired words from the event. +A `:' separates the event specification from the word designator. It +may be omitted if the word designator begins with a `^', `$', +`*', `-', or `%'. Words are numbered from the beginning +of the line, with the first word being denoted by 0 (zero). Words are +inserted into the current line separated by single spaces. + +

    For example, + +

    +
    !!
    designates the preceding command. When you type this, the preceding +command is repeated in toto. + +
    !!:$
    designates the last argument of the preceding command. This may be +shortened to !$. + +
    !fi:2
    designates the second argument of the most recent command starting with +the letters fi. +
    + +

    Here are the word designators: + +

    +
    0 (zero)
    The 0th word. For many applications, this is the command word. + +
    n
    The nth word. + +
    ^
    The first argument; that is, word 1. + +
    $
    The last argument. + +
    %
    The word matched by the most recent `?string?' search. + +
    x-y
    A range of words; `-y' abbreviates `0-y'. + +
    *
    All of the words, except the 0th. This is a synonym for `1-$'. +It is not an error to use `*' if there is just one word in the event; +the empty string is returned in that case. + +
    x*
    Abbreviates `x-$' + +
    x-
    Abbreviates `x-$' like `x*', but omits the last word. + +
    + +

    If a word designator is supplied without an event specification, the +previous command is used as the event. + +

    +

    + +Previous: Word Designators, +Up: History Interaction + +
    + +

    9.3.3 Modifiers

    + +

    After the optional word designator, you can add a sequence of one or more +of the following modifiers, each preceded by a `:'. + +

    +
    h
    Remove a trailing pathname component, leaving only the head. + +
    t
    Remove all leading pathname components, leaving the tail. + +
    r
    Remove a trailing suffix of the form `.suffix', leaving +the basename. + +
    e
    Remove all but the trailing suffix. + +
    p
    Print the new command but do not execute it. + +
    q
    Quote the substituted words, escaping further substitutions. + +
    x
    Quote the substituted words as with `q', +but break into words at spaces, tabs, and newlines. + +
    s/old/new/
    Substitute new for the first occurrence of old in the +event line. Any delimiter may be used in place of `/'. +The delimiter may be quoted in old and new +with a single backslash. If `&' appears in new, +it is replaced by old. A single backslash will quote +the `&'. The final delimiter is optional if it is the last +character on the input line. + +
    &
    Repeat the previous substitution. + +
    g
    a
    Cause changes to be applied over the entire event line. Used in +conjunction with `s', as in gs/old/new/, +or with `&'. + +
    G
    Apply the following `s' modifier once to each word in the event. + +
    + +
    +

    + +Next: , +Previous: Command Line Editing, +Up: Top + +
    + +

    10 Installing Bash

    + +

    This chapter provides basic instructions for installing Bash on +the various supported platforms. The distribution supports the +gnu operating systems, nearly every version of Unix, and several +non-Unix systems such as BeOS and Interix. +Other independent ports exist for +ms-dos, os/2, and Windows platforms. + +

    + +
    +

    + +Next: , +Up: Installing Bash + +
    + +

    10.1 Basic Installation

    + +

    +These are installation instructions for Bash. + +

    The simplest way to compile Bash is: + +

      +
    1. cd to the directory containing the source code and type +`./configure' to configure Bash for your system. If you're +using csh on an old version of System V, you might need to +type `sh ./configure' instead to prevent csh from trying +to execute configure itself. + +

      Running configure takes some time. +While running, it prints messages telling which features it is +checking for. + +

    2. Type `make' to compile Bash and build the bashbug bug +reporting script. + +
    3. Optionally, type `make tests' to run the Bash test suite. + +
    4. Type `make install' to install bash and bashbug. +This will also install the manual pages and Info file. + +
    + +

    The configure shell script attempts to guess correct +values for various system-dependent variables used during +compilation. It uses those values to create a Makefile in +each directory of the package (the top directory, the +builtins, doc, and support directories, +each directory under lib, and several others). It also creates a +config.h file containing system-dependent definitions. +Finally, it creates a shell script named config.status that you +can run in the future to recreate the current configuration, a +file config.cache that saves the results of its tests to +speed up reconfiguring, and a file config.log containing +compiler output (useful mainly for debugging configure). +If at some point +config.cache contains results you don't want to keep, you +may remove or edit it. + +

    To find out more about the options and arguments that the +configure script understands, type + +

         bash-2.04$ ./configure --help
+
    +

    at the Bash prompt in your Bash source directory. + +

    If you need to do unusual things to compile Bash, please +try to figure out how configure could check whether or not +to do them, and mail diffs or instructions to +bash-maintainers@gnu.org so they can be +considered for the next release. + +

    The file configure.in is used to create configure +by a program called Autoconf. You only need +configure.in if you want to change it or regenerate +configure using a newer version of Autoconf. If +you do this, make sure you are using Autoconf version 2.50 or +newer. + +

    You can remove the program binaries and object files from the +source code directory by typing `make clean'. To also remove the +files that configure created (so you can compile Bash for +a different kind of computer), type `make distclean'. + +

    +

    + +Next: , +Previous: Basic Installation, +Up: Installing Bash + +
    + +

    10.2 Compilers and Options

    + +

    Some systems require unusual options for compilation or linking +that the configure script does not know about. You can +give configure initial values for variables by setting +them in the environment. Using a Bourne-compatible shell, you +can do that on the command line like this: + +

         CC=c89 CFLAGS=-O2 LIBS=-lposix ./configure
+
    +

    On systems that have the env program, you can do it like this: + +

         env CPPFLAGS=-I/usr/local/include LDFLAGS=-s ./configure
+
    +

    The configuration process uses GCC to build Bash if it +is available. + +

    +

    + +Next: , +Previous: Compilers and Options, +Up: Installing Bash + +
    + +

    10.3 Compiling For Multiple Architectures

    + +

    You can compile Bash for more than one kind of computer at the +same time, by placing the object files for each architecture in their +own directory. To do this, you must use a version of make that +supports the VPATH variable, such as GNU make. +cd to the +directory where you want the object files and executables to go and run +the configure script from the source directory. You may need to +supply the --srcdir=PATH argument to tell configure where the +source files are. configure automatically checks for the +source code in the directory that configure is in and in `..'. + +

    If you have to use a make that does not supports the VPATH +variable, you can compile Bash for one architecture at a +time in the source code directory. After you have installed +Bash for one architecture, use `make distclean' before +reconfiguring for another architecture. + +

    Alternatively, if your system supports symbolic links, you can use the +support/mkclone script to create a build tree which has +symbolic links back to each file in the source directory. Here's an +example that creates a build directory in the current directory from a +source directory /usr/gnu/src/bash-2.0: + +

         bash /usr/gnu/src/bash-2.0/support/mkclone -s /usr/gnu/src/bash-2.0 .
+
    +

    The mkclone script requires Bash, so you must have already built +Bash for at least one architecture before you can create build +directories for other architectures. + +

    +

    + +Next: , +Previous: Compiling For Multiple Architectures, +Up: Installing Bash + +
    + +

    10.4 Installation Names

    + +

    By default, `make install' will install into +/usr/local/bin, /usr/local/man, etc. You can +specify an installation prefix other than /usr/local by +giving configure the option --prefix=PATH, +or by specifying a value for the DESTDIR `make' +variable when running `make install'. + +

    You can specify separate installation prefixes for +architecture-specific files and architecture-independent files. +If you give configure the option +--exec-prefix=PATH, `make install' will use +PATH as the prefix for installing programs and libraries. +Documentation and other data files will still use the regular prefix. + +

    +

    + +Next: , +Previous: Installation Names, +Up: Installing Bash + +
    + +

    10.5 Specifying the System Type

    + +

    There may be some features configure can not figure out +automatically, but need to determine by the type of host Bash +will run on. Usually configure can figure that +out, but if it prints a message saying it can not guess the host +type, give it the --host=TYPE option. `TYPE' can +either be a short name for the system type, such as `sun4', +or a canonical name with three fields: `CPU-COMPANY-SYSTEM' +(e.g., `i386-unknown-freebsd4.2'). + +

    See the file support/config.sub for the possible +values of each field. + +

    +

    + +Next: , +Previous: Specifying the System Type, +Up: Installing Bash + +
    + +

    10.6 Sharing Defaults

    + +

    If you want to set default values for configure scripts to +share, you can create a site shell script called +config.site that gives default values for variables like +CC, cache_file, and prefix. configure +looks for PREFIX/share/config.site if it exists, then +PREFIX/etc/config.site if it exists. Or, you can set the +CONFIG_SITE environment variable to the location of the site +script. A warning: the Bash configure looks for a site script, +but not all configure scripts do. + +

    +

    + +Next: , +Previous: Sharing Defaults, +Up: Installing Bash + +
    + +

    10.7 Operation Controls

    + +

    configure recognizes the following options to control how it +operates. + +

    +
    --cache-file=file
    Use and save the results of the tests in +file instead of ./config.cache. Set file to +/dev/null to disable caching, for debugging +configure. + +
    --help
    Print a summary of the options to configure, and exit. + +
    --quiet
    --silent
    -q
    Do not print messages saying which checks are being made. + +
    --srcdir=dir
    Look for the Bash source code in directory dir. Usually +configure can determine that directory automatically. + +
    --version
    Print the version of Autoconf used to generate the configure +script, and exit. +
    + +

    configure also accepts some other, not widely used, boilerplate +options. `configure --help' prints the complete list. + +

    +

    + +Previous: Operation Controls, +Up: Installing Bash + +
    + +

    10.8 Optional Features

    + +

    The Bash configure has a number of --enable-feature +options, where feature indicates an optional part of Bash. +There are also several --with-package options, +where package is something like `bash-malloc' or `purify'. +To turn off the default use of a package, use +--without-package. To configure Bash without a feature +that is enabled by default, use --disable-feature. + +

    Here is a complete list of the --enable- and +--with- options that the Bash configure recognizes. + +

    +
    --with-afs
    Define if you are using the Andrew File System from Transarc. + +
    --with-bash-malloc
    Use the Bash version of +malloc in the directory lib/malloc. This is not the same +malloc that appears in gnu libc, but an older version +originally derived from the 4.2 bsd malloc. This malloc +is very fast, but wastes some space on each allocation. +This option is enabled by default. +The NOTES file contains a list of systems for +which this should be turned off, and configure disables this +option automatically for a number of systems. + +
    --with-curses
    Use the curses library instead of the termcap library. This should +be supplied if your system has an inadequate or incomplete termcap +database. + +
    --with-gnu-malloc
    A synonym for --with-bash-malloc. + +
    --with-installed-readline[=PREFIX]
    Define this to make Bash link with a locally-installed version of Readline +rather than the version in lib/readline. This works only with +Readline 5.0 and later versions. If PREFIX is yes or not +supplied, configure uses the values of the make variables +includedir and libdir, which are subdirectories of prefix +by default, to find the installed version of Readline if it is not in +the standard system include and library directories. +If PREFIX is no, Bash links with the version in +lib/readline. +If PREFIX is set to any other value, configure treats it as +a directory pathname and looks for +the installed version of Readline in subdirectories of that directory +(include files in PREFIX/include and the library in +PREFIX/lib). + +
    --with-purify
    Define this to use the Purify memory allocation checker from Rational +Software. + +
    --enable-minimal-config
    This produces a shell with minimal features, close to the historical +Bourne shell. +
    + +

    There are several --enable- options that alter how Bash is +compiled and linked, rather than changing run-time features. + +

    +
    --enable-largefile
    Enable support for large files if the operating system requires special compiler options +to build programs which can access large files. This is enabled by +default, if the operating system provides large file support. + +
    --enable-profiling
    This builds a Bash binary that produces profiling information to be +processed by gprof each time it is executed. + +
    --enable-static-link
    This causes Bash to be linked statically, if gcc is being used. +This could be used to build a version to use as root's shell. +
    + +

    The `minimal-config' option can be used to disable all of +the following options, but it is processed first, so individual +options may be enabled using `enable-feature'. + +

    All of the following options except for `disabled-builtins' and +`xpg-echo-default' are +enabled by default, unless the operating system does not provide the +necessary support. + +

    +
    --enable-alias
    Allow alias expansion and include the alias and unalias +builtins (see Aliases). + +
    --enable-arith-for-command
    Include support for the alternate form of the for command +that behaves like the C language for statement +(see Looping Constructs). + +
    --enable-array-variables
    Include support for one-dimensional array shell variables +(see Arrays). + +
    --enable-bang-history
    Include support for csh-like history substitution +(see History Interaction). + +
    --enable-brace-expansion
    Include csh-like brace expansion +( b{a,b}c ==> bac bbc ). +See Brace Expansion, for a complete description. + +
    --enable-command-timing
    Include support for recognizing time as a reserved word and for +displaying timing statistics for the pipeline following time +(see Pipelines). +This allows pipelines as well as shell builtins and functions to be timed. + +
    --enable-cond-command
    Include support for the [[ conditional command. +(see Conditional Constructs). + +
    --enable-cond-regexp
    Include support for matching POSIX regular expressions using the +`=~' binary operator in the [[ conditional command. +(see Conditional Constructs). + +
    --enable-debugger
    Include support for the bash debugger (distributed separately). + +
    --enable-directory-stack
    Include support for a csh-like directory stack and the +pushd, popd, and dirs builtins +(see The Directory Stack). + +
    --enable-disabled-builtins
    Allow builtin commands to be invoked via `builtin xxx' +even after xxx has been disabled using `enable -n xxx'. +See Bash Builtins, for details of the builtin and +enable builtin commands. + +
    --enable-dparen-arithmetic
    Include support for the ((...)) command +(see Conditional Constructs). + +
    --enable-extended-glob
    Include support for the extended pattern matching features described +above under Pattern Matching. + +
    --enable-help-builtin
    Include the help builtin, which displays help on shell builtins and +variables (see Bash Builtins). + +
    --enable-history
    Include command history and the fc and history +builtin commands (see Bash History Facilities). + +
    --enable-job-control
    This enables the job control features (see Job Control), +if the operating system supports them. + +
    --enable-multibyte
    This enables support for multibyte characters if the operating +system provides the necessary support. + +
    --enable-net-redirections
    This enables the special handling of filenames of the form +/dev/tcp/host/port and +/dev/udp/host/port +when used in redirections (see Redirections). + +
    --enable-process-substitution
    This enables process substitution (see Process Substitution) if +the operating system provides the necessary support. + +
    --enable-progcomp
    Enable the programmable completion facilities +(see Programmable Completion). +If Readline is not enabled, this option has no effect. + +
    --enable-prompt-string-decoding
    Turn on the interpretation of a number of backslash-escaped characters +in the $PS1, $PS2, $PS3, and $PS4 prompt +strings. See Printing a Prompt, for a complete list of prompt +string escape sequences. + +
    --enable-readline
    Include support for command-line editing and history with the Bash +version of the Readline library (see Command Line Editing). + +
    --enable-restricted
    Include support for a restricted shell. If this is enabled, Bash, +when called as rbash, enters a restricted mode. See +The Restricted Shell, for a description of restricted mode. + +
    --enable-select
    Include the select builtin, which allows the generation of simple +menus (see Conditional Constructs). + +
    --enable-separate-helpfiles
    Use external files for the documentation displayed by the help builtin +instead of storing the text internally. + +
    --enable-single-help-strings
    Store the text displayed by the help builtin as a single string for +each help topic. This aids in translating the text to different languages. +You may need to disable this if your compiler cannot handle very long string +literals. + +
    --enable-strict-posix-default
    Make Bash posix-conformant by default (see Bash POSIX Mode). + +
    --enable-usg-echo-default
    A synonym for --enable-xpg-echo-default. + +
    --enable-xpg-echo-default
    Make the echo builtin expand backslash-escaped characters by default, +without requiring the -e option. +This sets the default value of the xpg_echo shell option to on, +which makes the Bash echo behave more like the version specified in +the Single Unix Specification, version 3. +See Bash Builtins, for a description of the escape sequences that +echo recognizes. + +
    + +

    The file config-top.h contains C Preprocessor +`#define' statements for options which are not settable from +configure. +Some of these are not meant to be changed; beware of the consequences if +you do. +Read the comments associated with each definition for more +information about its effect. + +

    +

    + +Next: , +Previous: Installing Bash, +Up: Top + +
    + +

    Appendix A Reporting Bugs

    + +

    Please report all bugs you find in Bash. +But first, you should +make sure that it really is a bug, and that it appears in the latest +version of Bash. +The latest version of Bash is always available for FTP from +ftp://ftp.gnu.org/pub/bash/. + +

    Once you have determined that a bug actually exists, use the +bashbug command to submit a bug report. +If you have a fix, you are encouraged to mail that as well! +Suggestions and `philosophical' bug reports may be mailed +to bug-bash@gnu.org or posted to the Usenet +newsgroup gnu.bash.bug. + +

    All bug reports should include: +

      +
    • The version number of Bash. +
    • The hardware and operating system. +
    • The compiler used to compile Bash. +
    • A description of the bug behaviour. +
    • A short script or `recipe' which exercises the bug and may be used +to reproduce it. +
    + +

    bashbug inserts the first three items automatically into +the template it provides for filing a bug report. + +

    Please send all reports concerning this manual to +chet@po.CWRU.Edu. + +

    +

    + +Next: , +Previous: Reporting Bugs, +Up: Top + +
    + +

    Appendix B Major Differences From The Bourne Shell

    + +

    Bash implements essentially the same grammar, parameter and +variable expansion, redirection, and quoting as the Bourne Shell. +Bash uses the posix standard as the specification of +how these features are to be implemented. There are some +differences between the traditional Bourne shell and Bash; this +section quickly details the differences of significance. A +number of these differences are explained in greater depth in +previous sections. +This section uses the version of sh included in SVR4.2 (the +last version of the historical Bourne shell) as the baseline reference. + +

      +
    • Bash is posix-conformant, even where the posix specification +differs from traditional sh behavior (see Bash POSIX Mode). + +
    • Bash has multi-character invocation options (see Invoking Bash). + +
    • Bash has command-line editing (see Command Line Editing) and +the bind builtin. + +
    • Bash provides a programmable word completion mechanism +(see Programmable Completion), and two builtin commands, +complete and compgen, to manipulate it. + +
    • Bash has command history (see Bash History Facilities) and the +history and fc builtins to manipulate it. +The Bash history list maintains timestamp information and uses the +value of the HISTTIMEFORMAT variable to display it. + +
    • Bash implements csh-like history expansion +(see History Interaction). + +
    • Bash has one-dimensional array variables (see Arrays), and the +appropriate variable expansions and assignment syntax to use them. +Several of the Bash builtins take options to act on arrays. +Bash provides a number of built-in array variables. + +
    • The $'...' quoting syntax, which expands ANSI-C +backslash-escaped characters in the text between the single quotes, +is supported (see ANSI-C Quoting). + +
    • Bash supports the $"..." quoting syntax to do +locale-specific translation of the characters between the double +quotes. The -D, --dump-strings, and --dump-po-strings +invocation options list the translatable strings found in a script +(see Locale Translation). + +
    • Bash implements the ! keyword to negate the return value of +a pipeline (see Pipelines). +Very useful when an if statement needs to act only if a test fails. +The Bash `-o pipefail' option to set will cause a pipeline to +return a failure status if any command fails. + +
    • Bash has the time reserved word and command timing (see Pipelines). +The display of the timing statistics may be controlled with the +TIMEFORMAT variable. + +
    • Bash implements the for (( expr1 ; expr2 ; expr3 )) +arithmetic for command, similar to the C language (see Looping Constructs). + +
    • Bash includes the select compound command, which allows the +generation of simple menus (see Conditional Constructs). + +
    • Bash includes the [[ compound command, which makes conditional +testing part of the shell grammar (see Conditional Constructs), including +optional regular expression matching. + +
    • Bash provides optional case-insensitive matching for the case and +[[ constructs. + +
    • Bash includes brace expansion (see Brace Expansion) and tilde +expansion (see Tilde Expansion). + +
    • Bash implements command aliases and the alias and unalias +builtins (see Aliases). + +
    • Bash provides shell arithmetic, the (( compound command +(see Conditional Constructs), +and arithmetic expansion (see Shell Arithmetic). + +
    • Variables present in the shell's initial environment are automatically +exported to child processes. The Bourne shell does not normally do +this unless the variables are explicitly marked using the export +command. + +
    • Bash supports the `+=' assignment operator, which appends to the value +of the variable named on the left hand side. + +
    • Bash includes the posix pattern removal `%', `#', `%%' +and `##' expansions to remove leading or trailing substrings from +variable values (see Shell Parameter Expansion). + +
    • The expansion ${#xx}, which returns the length of ${xx}, +is supported (see Shell Parameter Expansion). + +
    • The expansion ${var:offset[:length]}, +which expands to the substring of var's value of length +length, beginning at offset, is present +(see Shell Parameter Expansion). + +
    • The expansion +${var/[/]pattern[/replacement]}, +which matches pattern and replaces it with replacement in +the value of var, is available (see Shell Parameter Expansion). + +
    • The expansion ${!prefix}* expansion, which expands to +the names of all shell variables whose names begin with prefix, +is available (see Shell Parameter Expansion). + +
    • Bash has indirect variable expansion using ${!word} +(see Shell Parameter Expansion). + +
    • Bash can expand positional parameters beyond $9 using +${num}. + +
    • The posix $() form of command substitution +is implemented (see Command Substitution), +and preferred to the Bourne shell's `` (which +is also implemented for backwards compatibility). + +
    • Bash has process substitution (see Process Substitution). + +
    • Bash automatically assigns variables that provide information about the +current user (UID, EUID, and GROUPS), the current host +(HOSTTYPE, OSTYPE, MACHTYPE, and HOSTNAME), +and the instance of Bash that is running (BASH, +BASH_VERSION, and BASH_VERSINFO). See Bash Variables, +for details. + +
    • The IFS variable is used to split only the results of expansion, +not all words (see Word Splitting). +This closes a longstanding shell security hole. + +
    • Bash implements the full set of posix filename expansion operators, +including character classes, equivalence classes, and +collating symbols (see Filename Expansion). + +
    • Bash implements extended pattern matching features when the extglob +shell option is enabled (see Pattern Matching). + +
    • It is possible to have a variable and a function with the same name; +sh does not separate the two name spaces. + +
    • Bash functions are permitted to have local variables using the +local builtin, and thus useful recursive functions may be written +(see Bash Builtins). + +
    • Variable assignments preceding commands affect only that command, even +builtins and functions (see Environment). +In sh, all variable assignments +preceding commands are global unless the command is executed from the +file system. + +
    • Bash performs filename expansion on filenames specified as operands +to input and output redirection operators (see Redirections). + +
    • Bash contains the `<>' redirection operator, allowing a file to be +opened for both reading and writing, and the `&>' redirection +operator, for directing standard output and standard error to the same +file (see Redirections). + +
    • Bash includes the `<<<' redirection operator, allowing a string to +be used as the standard input to a command. + +
    • Bash implements the `[n]<&word' and `[n]>&word' +redirection operators, which move one file descriptor to another. + +
    • Bash treats a number of filenames specially when they are +used in redirection operators (see Redirections). + +
    • Bash can open network connections to arbitrary machines and services +with the redirection operators (see Redirections). + +
    • The noclobber option is available to avoid overwriting existing +files with output redirection (see The Set Builtin). +The `>|' redirection operator may be used to override noclobber. + +
    • The Bash cd and pwd builtins (see Bourne Shell Builtins) +each take -L and -P options to switch between logical and +physical modes. + +
    • Bash allows a function to override a builtin with the same name, and provides +access to that builtin's functionality within the function via the +builtin and command builtins (see Bash Builtins). + +
    • The command builtin allows selective disabling of functions +when command lookup is performed (see Bash Builtins). + +
    • Individual builtins may be enabled or disabled using the enable +builtin (see Bash Builtins). + +
    • The Bash exec builtin takes additional options that allow users +to control the contents of the environment passed to the executed +command, and what the zeroth argument to the command is to be +(see Bourne Shell Builtins). + +
    • Shell functions may be exported to children via the environment +using export -f (see Shell Functions). + +
    • The Bash export, readonly, and declare builtins can +take a -f option to act on shell functions, a -p option to +display variables with various attributes set in a format that can be +used as shell input, a -n option to remove various variable +attributes, and `name=value' arguments to set variable attributes +and values simultaneously. + +
    • The Bash hash builtin allows a name to be associated with +an arbitrary filename, even when that filename cannot be found by +searching the $PATH, using `hash -p' +(see Bourne Shell Builtins). + +
    • Bash includes a help builtin for quick reference to shell +facilities (see Bash Builtins). + +
    • The printf builtin is available to display formatted output +(see Bash Builtins). + +
    • The Bash read builtin (see Bash Builtins) +will read a line ending in `\' with +the -r option, and will use the REPLY variable as a +default if no non-option arguments are supplied. +The Bash read builtin +also accepts a prompt string with the -p option and will use +Readline to obtain the line when given the -e option. +The read builtin also has additional options to control input: +the -s option will turn off echoing of input characters as +they are read, the -t option will allow read to time out +if input does not arrive within a specified number of seconds, the +-n option will allow reading only a specified number of +characters rather than a full line, and the -d option will read +until a particular character rather than newline. + +
    • The return builtin may be used to abort execution of scripts +executed with the . or source builtins +(see Bourne Shell Builtins). + +
    • Bash includes the shopt builtin, for finer control of shell +optional capabilities (see The Shopt Builtin), and allows these options +to be set and unset at shell invocation (see Invoking Bash). + +
    • Bash has much more optional behavior controllable with the set +builtin (see The Set Builtin). + +
    • The `-x' (xtrace) option displays commands other than +simple commands when performing an execution trace +(see The Set Builtin). + +
    • The test builtin (see Bourne Shell Builtins) +is slightly different, as it implements the posix algorithm, +which specifies the behavior based on the number of arguments. + +
    • Bash includes the caller builtin, which displays the context of +any active subroutine call (a shell function or a script executed with +the . or source builtins). This supports the bash +debugger. + +
    • The trap builtin (see Bourne Shell Builtins) allows a +DEBUG pseudo-signal specification, similar to EXIT. +Commands specified with a DEBUG trap are executed before every +simple command, for command, case command, +select command, every arithmetic for command, and before +the first command executes in a shell function. +The DEBUG trap is not inherited by shell functions unless the +function has been given the trace attribute or the +functrace option has been enabled using the shopt builtin. +The extdebug shell option has additional effects on the +DEBUG trap. + +

      The trap builtin (see Bourne Shell Builtins) allows an +ERR pseudo-signal specification, similar to EXIT and DEBUG. +Commands specified with an ERR trap are executed after a simple +command fails, with a few exceptions. +The ERR trap is not inherited by shell functions unless the +-o errtrace option to the set builtin is enabled. + +

      The trap builtin (see Bourne Shell Builtins) allows a +RETURN pseudo-signal specification, similar to +EXIT and DEBUG. +Commands specified with an RETURN trap are executed before +execution resumes after a shell function or a shell script executed with +. or source returns. +The RETURN trap is not inherited by shell functions unless the +function has been given the trace attribute or the +functrace option has been enabled using the shopt builtin. + +

    • The Bash type builtin is more extensive and gives more information +about the names it finds (see Bash Builtins). + +
    • The Bash umask builtin permits a -p option to cause +the output to be displayed in the form of a umask command +that may be reused as input (see Bourne Shell Builtins). + +
    • Bash implements a csh-like directory stack, and provides the +pushd, popd, and dirs builtins to manipulate it +(see The Directory Stack). +Bash also makes the directory stack visible as the value of the +DIRSTACK shell variable. + +
    • Bash interprets special backslash-escaped characters in the prompt +strings when interactive (see Printing a Prompt). + +
    • The Bash restricted mode is more useful (see The Restricted Shell); +the SVR4.2 shell restricted mode is too limited. + +
    • The disown builtin can remove a job from the internal shell +job table (see Job Control Builtins) or suppress the sending +of SIGHUP to a job when the shell exits as the result of a +SIGHUP. + +
    • Bash includes a number of features to support a separate debugger for +shell scripts. + +
    • The SVR4.2 shell has two privilege-related builtins +(mldmode and priv) not present in Bash. + +
    • Bash does not have the stop or newgrp builtins. + +
    • Bash does not use the SHACCT variable or perform shell accounting. + +
    • The SVR4.2 sh uses a TIMEOUT variable like Bash uses +TMOUT. + +
    + +

    More features unique to Bash may be found in Bash Features. + +

    B.1 Implementation Differences From The SVR4.2 Shell

    + +

    Since Bash is a completely new implementation, it does not suffer from +many of the limitations of the SVR4.2 shell. For instance: + +

      +
    • Bash does not fork a subshell when redirecting into or out of +a shell control structure such as an if or while +statement. + +
    • Bash does not allow unbalanced quotes. The SVR4.2 shell will silently +insert a needed closing quote at EOF under certain circumstances. +This can be the cause of some hard-to-find errors. + +
    • The SVR4.2 shell uses a baroque memory management scheme based on +trapping SIGSEGV. If the shell is started from a process with +SIGSEGV blocked (e.g., by using the system() C library +function call), it misbehaves badly. + +
    • In a questionable attempt at security, the SVR4.2 shell, +when invoked without the -p option, will alter its real +and effective uid and gid if they are less than some +magic threshold value, commonly 100. +This can lead to unexpected results. + +
    • The SVR4.2 shell does not allow users to trap SIGSEGV, +SIGALRM, or SIGCHLD. + +
    • The SVR4.2 shell does not allow the IFS, MAILCHECK, +PATH, PS1, or PS2 variables to be unset. + +
    • The SVR4.2 shell treats `^' as the undocumented equivalent of +`|'. + +
    • Bash allows multiple option arguments when it is invoked (-x -v); +the SVR4.2 shell allows only one option argument (-xv). In +fact, some versions of the shell dump core if the second argument begins +with a `-'. + +
    • The SVR4.2 shell exits a script if any builtin fails; Bash exits +a script only if one of the posix special builtins fails, and +only for certain failures, as enumerated in the posix standard. + +
    • The SVR4.2 shell behaves differently when invoked as jsh +(it turns on job control). +
    + +
    +

    + +Next: , +Previous: Major Differences From The Bourne Shell, +Up: Top + +
    + +

    Appendix C Copying This Manual

    + + + +
    +

    + +Up: Copying This Manual + +
    + +

    C.1 GNU Free Documentation License

    + +

    Version 1.2, November 2002
    + +
         Copyright © 2000,2001,2002 Free Software Foundation, Inc.
+     59 Temple Place, Suite 330, Boston, MA  02111-1307, USA
+     
+     Everyone is permitted to copy and distribute verbatim copies
+     of this license document, but changing it is not allowed.
+
    +
      +
    1. PREAMBLE + +

      The purpose of this License is to make a manual, textbook, or other +functional and useful document free in the sense of freedom: to +assure everyone the effective freedom to copy and redistribute it, +with or without modifying it, either commercially or noncommercially. +Secondarily, this License preserves for the author and publisher a way +to get credit for their work, while not being considered responsible +for modifications made by others. + +

      This License is a kind of “copyleft”, which means that derivative +works of the document must themselves be free in the same sense. It +complements the GNU General Public License, which is a copyleft +license designed for free software. + +

      We have designed this License in order to use it for manuals for free +software, because free software needs free documentation: a free +program should come with manuals providing the same freedoms that the +software does. But this License is not limited to software manuals; +it can be used for any textual work, regardless of subject matter or +whether it is published as a printed book. We recommend this License +principally for works whose purpose is instruction or reference. + +

    2. APPLICABILITY AND DEFINITIONS + +

      This License applies to any manual or other work, in any medium, that +contains a notice placed by the copyright holder saying it can be +distributed under the terms of this License. Such a notice grants a +world-wide, royalty-free license, unlimited in duration, to use that +work under the conditions stated herein. The “Document”, below, +refers to any such manual or work. Any member of the public is a +licensee, and is addressed as “you”. You accept the license if you +copy, modify or distribute the work in a way requiring permission +under copyright law. + +

      A “Modified Version” of the Document means any work containing the +Document or a portion of it, either copied verbatim, or with +modifications and/or translated into another language. + +

      A “Secondary Section” is a named appendix or a front-matter section +of the Document that deals exclusively with the relationship of the +publishers or authors of the Document to the Document's overall +subject (or to related matters) and contains nothing that could fall +directly within that overall subject. (Thus, if the Document is in +part a textbook of mathematics, a Secondary Section may not explain +any mathematics.) The relationship could be a matter of historical +connection with the subject or with related matters, or of legal, +commercial, philosophical, ethical or political position regarding +them. + +

      The “Invariant Sections” are certain Secondary Sections whose titles +are designated, as being those of Invariant Sections, in the notice +that says that the Document is released under this License. If a +section does not fit the above definition of Secondary then it is not +allowed to be designated as Invariant. The Document may contain zero +Invariant Sections. If the Document does not identify any Invariant +Sections then there are none. + +

      The “Cover Texts” are certain short passages of text that are listed, +as Front-Cover Texts or Back-Cover Texts, in the notice that says that +the Document is released under this License. A Front-Cover Text may +be at most 5 words, and a Back-Cover Text may be at most 25 words. + +

      A “Transparent” copy of the Document means a machine-readable copy, +represented in a format whose specification is available to the +general public, that is suitable for revising the document +straightforwardly with generic text editors or (for images composed of +pixels) generic paint programs or (for drawings) some widely available +drawing editor, and that is suitable for input to text formatters or +for automatic translation to a variety of formats suitable for input +to text formatters. A copy made in an otherwise Transparent file +format whose markup, or absence of markup, has been arranged to thwart +or discourage subsequent modification by readers is not Transparent. +An image format is not Transparent if used for any substantial amount +of text. A copy that is not “Transparent” is called “Opaque”. + +

      Examples of suitable formats for Transparent copies include plain +ascii without markup, Texinfo input format, LaTeX input +format, SGML or XML using a publicly available +DTD, and standard-conforming simple HTML, +PostScript or PDF designed for human modification. Examples +of transparent image formats include PNG, XCF and +JPG. Opaque formats include proprietary formats that can be +read and edited only by proprietary word processors, SGML or +XML for which the DTD and/or processing tools are +not generally available, and the machine-generated HTML, +PostScript or PDF produced by some word processors for +output purposes only. + +

      The “Title Page” means, for a printed book, the title page itself, +plus such following pages as are needed to hold, legibly, the material +this License requires to appear in the title page. For works in +formats which do not have any title page as such, “Title Page” means +the text near the most prominent appearance of the work's title, +preceding the beginning of the body of the text. + +

      A section “Entitled XYZ” means a named subunit of the Document whose +title either is precisely XYZ or contains XYZ in parentheses following +text that translates XYZ in another language. (Here XYZ stands for a +specific section name mentioned below, such as “Acknowledgements”, +“Dedications”, “Endorsements”, or “History”.) To “Preserve the Title” +of such a section when you modify the Document means that it remains a +section “Entitled XYZ” according to this definition. + +

      The Document may include Warranty Disclaimers next to the notice which +states that this License applies to the Document. These Warranty +Disclaimers are considered to be included by reference in this +License, but only as regards disclaiming warranties: any other +implication that these Warranty Disclaimers may have is void and has +no effect on the meaning of this License. + +

    3. VERBATIM COPYING + +

      You may copy and distribute the Document in any medium, either +commercially or noncommercially, provided that this License, the +copyright notices, and the license notice saying this License applies +to the Document are reproduced in all copies, and that you add no other +conditions whatsoever to those of this License. You may not use +technical measures to obstruct or control the reading or further +copying of the copies you make or distribute. However, you may accept +compensation in exchange for copies. If you distribute a large enough +number of copies you must also follow the conditions in section 3. + +

      You may also lend copies, under the same conditions stated above, and +you may publicly display copies. + +

    4. COPYING IN QUANTITY + +

      If you publish printed copies (or copies in media that commonly have +printed covers) of the Document, numbering more than 100, and the +Document's license notice requires Cover Texts, you must enclose the +copies in covers that carry, clearly and legibly, all these Cover +Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on +the back cover. Both covers must also clearly and legibly identify +you as the publisher of these copies. The front cover must present +the full title with all words of the title equally prominent and +visible. You may add other material on the covers in addition. +Copying with changes limited to the covers, as long as they preserve +the title of the Document and satisfy these conditions, can be treated +as verbatim copying in other respects. + +

      If the required texts for either cover are too voluminous to fit +legibly, you should put the first ones listed (as many as fit +reasonably) on the actual cover, and continue the rest onto adjacent +pages. + +

      If you publish or distribute Opaque copies of the Document numbering +more than 100, you must either include a machine-readable Transparent +copy along with each Opaque copy, or state in or with each Opaque copy +a computer-network location from which the general network-using +public has access to download using public-standard network protocols +a complete Transparent copy of the Document, free of added material. +If you use the latter option, you must take reasonably prudent steps, +when you begin distribution of Opaque copies in quantity, to ensure +that this Transparent copy will remain thus accessible at the stated +location until at least one year after the last time you distribute an +Opaque copy (directly or through your agents or retailers) of that +edition to the public. + +

      It is requested, but not required, that you contact the authors of the +Document well before redistributing any large number of copies, to give +them a chance to provide you with an updated version of the Document. + +

    5. MODIFICATIONS + +

      You may copy and distribute a Modified Version of the Document under +the conditions of sections 2 and 3 above, provided that you release +the Modified Version under precisely this License, with the Modified +Version filling the role of the Document, thus licensing distribution +and modification of the Modified Version to whoever possesses a copy +of it. In addition, you must do these things in the Modified Version: + +

        +
      1. Use in the Title Page (and on the covers, if any) a title distinct +from that of the Document, and from those of previous versions +(which should, if there were any, be listed in the History section +of the Document). You may use the same title as a previous version +if the original publisher of that version gives permission. + +
      2. List on the Title Page, as authors, one or more persons or entities +responsible for authorship of the modifications in the Modified +Version, together with at least five of the principal authors of the +Document (all of its principal authors, if it has fewer than five), +unless they release you from this requirement. + +
      3. State on the Title page the name of the publisher of the +Modified Version, as the publisher. + +
      4. Preserve all the copyright notices of the Document. + +
      5. Add an appropriate copyright notice for your modifications +adjacent to the other copyright notices. + +
      6. Include, immediately after the copyright notices, a license notice +giving the public permission to use the Modified Version under the +terms of this License, in the form shown in the Addendum below. + +
      7. Preserve in that license notice the full lists of Invariant Sections +and required Cover Texts given in the Document's license notice. + +
      8. Include an unaltered copy of this License. + +
      9. Preserve the section Entitled “History”, Preserve its Title, and add +to it an item stating at least the title, year, new authors, and +publisher of the Modified Version as given on the Title Page. If +there is no section Entitled “History” in the Document, create one +stating the title, year, authors, and publisher of the Document as +given on its Title Page, then add an item describing the Modified +Version as stated in the previous sentence. + +
      10. Preserve the network location, if any, given in the Document for +public access to a Transparent copy of the Document, and likewise +the network locations given in the Document for previous versions +it was based on. These may be placed in the “History” section. +You may omit a network location for a work that was published at +least four years before the Document itself, or if the original +publisher of the version it refers to gives permission. + +
      11. For any section Entitled “Acknowledgements” or “Dedications”, Preserve +the Title of the section, and preserve in the section all the +substance and tone of each of the contributor acknowledgements and/or +dedications given therein. + +
      12. Preserve all the Invariant Sections of the Document, +unaltered in their text and in their titles. Section numbers +or the equivalent are not considered part of the section titles. + +
      13. Delete any section Entitled “Endorsements”. Such a section +may not be included in the Modified Version. + +
      14. Do not retitle any existing section to be Entitled “Endorsements” or +to conflict in title with any Invariant Section. + +
      15. Preserve any Warranty Disclaimers. +
      + +

      If the Modified Version includes new front-matter sections or +appendices that qualify as Secondary Sections and contain no material +copied from the Document, you may at your option designate some or all +of these sections as invariant. To do this, add their titles to the +list of Invariant Sections in the Modified Version's license notice. +These titles must be distinct from any other section titles. + +

      You may add a section Entitled “Endorsements”, provided it contains +nothing but endorsements of your Modified Version by various +parties—for example, statements of peer review or that the text has +been approved by an organization as the authoritative definition of a +standard. + +

      You may add a passage of up to five words as a Front-Cover Text, and a +passage of up to 25 words as a Back-Cover Text, to the end of the list +of Cover Texts in the Modified Version. Only one passage of +Front-Cover Text and one of Back-Cover Text may be added by (or +through arrangements made by) any one entity. If the Document already +includes a cover text for the same cover, previously added by you or +by arrangement made by the same entity you are acting on behalf of, +you may not add another; but you may replace the old one, on explicit +permission from the previous publisher that added the old one. + +

      The author(s) and publisher(s) of the Document do not by this License +give permission to use their names for publicity for or to assert or +imply endorsement of any Modified Version. + +

    6. COMBINING DOCUMENTS + +

      You may combine the Document with other documents released under this +License, under the terms defined in section 4 above for modified +versions, provided that you include in the combination all of the +Invariant Sections of all of the original documents, unmodified, and +list them all as Invariant Sections of your combined work in its +license notice, and that you preserve all their Warranty Disclaimers. + +

      The combined work need only contain one copy of this License, and +multiple identical Invariant Sections may be replaced with a single +copy. If there are multiple Invariant Sections with the same name but +different contents, make the title of each such section unique by +adding at the end of it, in parentheses, the name of the original +author or publisher of that section if known, or else a unique number. +Make the same adjustment to the section titles in the list of +Invariant Sections in the license notice of the combined work. + +

      In the combination, you must combine any sections Entitled “History” +in the various original documents, forming one section Entitled +“History”; likewise combine any sections Entitled “Acknowledgements”, +and any sections Entitled “Dedications”. You must delete all +sections Entitled “Endorsements.” + +

    7. COLLECTIONS OF DOCUMENTS + +

      You may make a collection consisting of the Document and other documents +released under this License, and replace the individual copies of this +License in the various documents with a single copy that is included in +the collection, provided that you follow the rules of this License for +verbatim copying of each of the documents in all other respects. + +

      You may extract a single document from such a collection, and distribute +it individually under this License, provided you insert a copy of this +License into the extracted document, and follow this License in all +other respects regarding verbatim copying of that document. + +

    8. AGGREGATION WITH INDEPENDENT WORKS + +

      A compilation of the Document or its derivatives with other separate +and independent documents or works, in or on a volume of a storage or +distribution medium, is called an “aggregate” if the copyright +resulting from the compilation is not used to limit the legal rights +of the compilation's users beyond what the individual works permit. +When the Document is included an aggregate, this License does not +apply to the other works in the aggregate which are not themselves +derivative works of the Document. + +

      If the Cover Text requirement of section 3 is applicable to these +copies of the Document, then if the Document is less than one half of +the entire aggregate, the Document's Cover Texts may be placed on +covers that bracket the Document within the aggregate, or the +electronic equivalent of covers if the Document is in electronic form. +Otherwise they must appear on printed covers that bracket the whole +aggregate. + +

    9. TRANSLATION + +

      Translation is considered a kind of modification, so you may +distribute translations of the Document under the terms of section 4. +Replacing Invariant Sections with translations requires special +permission from their copyright holders, but you may include +translations of some or all Invariant Sections in addition to the +original versions of these Invariant Sections. You may include a +translation of this License, and all the license notices in the +Document, and any Warranty Disclaimers, provided that you also include +the original English version of this License and the original versions +of those notices and disclaimers. In case of a disagreement between +the translation and the original version of this License or a notice +or disclaimer, the original version will prevail. + +

      If a section in the Document is Entitled “Acknowledgements”, +“Dedications”, or “History”, the requirement (section 4) to Preserve +its Title (section 1) will typically require changing the actual +title. + +

    10. TERMINATION + +

      You may not copy, modify, sublicense, or distribute the Document except +as expressly provided for under this License. Any other attempt to +copy, modify, sublicense or distribute the Document is void, and will +automatically terminate your rights under this License. However, +parties who have received copies, or rights, from you under this +License will not have their licenses terminated so long as such +parties remain in full compliance. + +

    11. FUTURE REVISIONS OF THIS LICENSE + +

      The Free Software Foundation may publish new, revised versions +of the GNU Free Documentation License from time to time. Such new +versions will be similar in spirit to the present version, but may +differ in detail to address new problems or concerns. See +http://www.gnu.org/copyleft/. + +

      Each version of the License is given a distinguishing version number. +If the Document specifies that a particular numbered version of this +License “or any later version” applies to it, you have the option of +following the terms and conditions either of that specified version or +of any later version that has been published (not as a draft) by the +Free Software Foundation. If the Document does not specify a version +number of this License, you may choose any version ever published (not +as a draft) by the Free Software Foundation. +

    + +

    C.1.1 ADDENDUM: How to use this License for your documents

    + +

    To use this License in a document you have written, include a copy of +the License in the document and put the following copyright and +license notices just after the title page: + +

           Copyright (C)  year  your name.
+       Permission is granted to copy, distribute and/or modify this document
+       under the terms of the GNU Free Documentation License, Version 1.2
+       or any later version published by the Free Software Foundation;
+       with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
+       A copy of the license is included in the section entitled ``GNU
+       Free Documentation License''.
+
    +

    If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, +replace the “with...Texts.” line with this: + +

             with the Invariant Sections being list their titles, with
+         the Front-Cover Texts being list, and with the Back-Cover Texts
+         being list.
+
    +

    If you have Invariant Sections without Cover Texts, or some other +combination of the three, merge those two alternatives to suit the +situation. + +

    If your document contains nontrivial examples of program code, we +recommend releasing these examples in parallel under your choice of +free software license, such as the GNU General Public License, +to permit their use in free software. + + + + +

    +

    + +Next: , +Previous: Copying This Manual, +Up: Top + +
    + +

    Index of Shell Builtin Commands

    + +
    +

    + +Next: , +Previous: Builtin Index, +Up: Top + +
    + +

    Index of Shell Reserved Words

    + + + +
    +

    + +Next: , +Previous: Reserved Word Index, +Up: Top + +
    + +

    Parameter and Variable Index

    + + + +
    +

    + +Next: , +Previous: Variable Index, +Up: Top + +
    + +

    Function Index

    + + + +
    +

    + +Previous: Function Index, +Up: Top + +
    + +

    Concept Index

    + + + + + diff --git a/doc/version.texi b/doc/version.texi index 42375e301..79525961d 100644 --- a/doc/version.texi +++ b/doc/version.texi @@ -1,10 +1,10 @@ @ignore -Copyright (C) 1988-2006 Free Software Foundation, Inc. +Copyright (C) 1988-2007 Free Software Foundation, Inc. @end ignore -@set LASTCHANGE Sat Dec 30 19:31:54 EST 2006 +@set LASTCHANGE Fri Jan 12 16:29:58 EST 2007 @set EDITION 3.2 @set VERSION 3.2 -@set UPDATED 30 December 2006 -@set UPDATED-MONTH December 2006 +@set UPDATED 12 January 2007 +@set UPDATED-MONTH January 2007 diff --git a/doc/version.texi~ b/doc/version.texi~ index 3e7083b49..42375e301 100644 --- a/doc/version.texi~ +++ b/doc/version.texi~ @@ -2,9 +2,9 @@ Copyright (C) 1988-2006 Free Software Foundation, Inc. @end ignore -@set LASTCHANGE Tue Dec 26 16:58:41 EST 2006 +@set LASTCHANGE Sat Dec 30 19:31:54 EST 2006 @set EDITION 3.2 @set VERSION 3.2 -@set UPDATED 26 December 2006 +@set UPDATED 30 December 2006 @set UPDATED-MONTH December 2006 diff --git a/execute_cmd.c b/execute_cmd.c index a0085d5cd..64fa7a022 100644 --- a/execute_cmd.c +++ b/execute_cmd.c @@ -3071,6 +3071,11 @@ run_builtin: if (command_line == 0) command_line = savestring (the_printed_command_except_trap); +#if defined (PROCESS_SUBSTITUTION) + if ((subshell_environment & SUBSHELL_COMSUB) && (simple_command->flags & CMD_NO_FORK) && fifos_pending() > 0) + simple_command->flags &= ~CMD_NO_FORK; +#endif + execute_disk_command (words, simple_command->redirects, command_line, pipe_in, pipe_out, async, fds_to_close, simple_command->flags); diff --git a/lib/readline/doc/hsuser.texi b/lib/readline/doc/hsuser.texi index c919e426e..87b354171 100644 --- a/lib/readline/doc/hsuser.texi +++ b/lib/readline/doc/hsuser.texi @@ -1,7 +1,7 @@ @ignore This file documents the user interface to the GNU History library. -Copyright (C) 1988-2006 Free Software Foundation, Inc. +Copyright (C) 1988-2007 Free Software Foundation, Inc. Authored by Brian Fox and Chet Ramey. Permission is granted to make and distribute verbatim copies of this manual @@ -97,7 +97,11 @@ to contain no more than @env{$HISTFILESIZE} lines. If @env{HISTFILESIZE} is not set, no truncation is performed. If the @env{HISTTIMEFORMAT} is set, the time stamp information -associated with each history entry is written to the history file. +associated with each history entry is written to the history file, +marked with the history comment character. +When the history file is read, lines beginning with the history +comment character followed immediately by a digit are interpreted +as timestamps for the previous history line. The builtin command @code{fc} may be used to list or edit and re-execute a portion of the history list. @@ -277,7 +281,10 @@ them, so that they are available for subsequent recall. This is most useful in conjunction with Readline. The shell allows control of the various characters used by the -history expansion mechanism with the @code{histchars} variable. +history expansion mechanism with the @code{histchars} variable, +as explained above (@pxref{Bash Variables}). The shell uses +the history comment character to mark history timestamps when +writing the history file. @end ifset @menu diff --git a/lib/readline/doc/hsuser.texi~ b/lib/readline/doc/hsuser.texi~ index ba033ca1f..846a8d940 100644 --- a/lib/readline/doc/hsuser.texi~ +++ b/lib/readline/doc/hsuser.texi~ @@ -97,7 +97,11 @@ to contain no more than @env{$HISTFILESIZE} lines. If @env{HISTFILESIZE} is not set, no truncation is performed. If the @env{HISTTIMEFORMAT} is set, the time stamp information -associated with each history entry is written to the history file. +associated with each history entry is written to the history file, +marked with the history comment character. +When the history file is read, lines beginning with the history +comment character followed immediately by a digit are interpreted +as timestamps for the previous history line. The builtin command @code{fc} may be used to list or edit and re-execute a portion of the history list. @@ -133,7 +137,7 @@ history list and history file. @item fc @btindex fc @example -@code{fc [-e @var{ename}] [-nlr] [@var{first}] [@var{last}]} +@code{fc [-e @var{ename}] [-lnr] [@var{first}] [@var{last}]} @code{fc -s [@var{pat}=@var{rep}] [@var{command}]} @end example @@ -277,7 +281,10 @@ them, so that they are available for subsequent recall. This is most useful in conjunction with Readline. The shell allows control of the various characters used by the -history expansion mechanism with the @code{histchars} variable. +history expansion mechanism with the @code{histchars} variable, +as explained above (@pxref{Bash Variables}). The shell uses +the history comment character to mark history timestamps when +writing the history file. @end ifset @menu diff --git a/lib/readline/doc/version.texi b/lib/readline/doc/version.texi index 42cc40360..bb7d5d406 100644 --- a/lib/readline/doc/version.texi +++ b/lib/readline/doc/version.texi @@ -1,10 +1,10 @@ @ignore -Copyright (C) 1988-2006 Free Software Foundation, Inc. +Copyright (C) 1988-2007 Free Software Foundation, Inc. @end ignore @set EDITION 5.2 @set VERSION 5.2 -@set UPDATED 30 December 2006 -@set UPDATED-MONTH December 2006 +@set UPDATED 12 January 2007 +@set UPDATED-MONTH January 2007 -@set LASTCHANGE Sat Dec 30 19:17:22 EST 2006 +@set LASTCHANGE Fri Jan 12 16:31:33 EST 2007 diff --git a/lib/readline/doc/version.texi~ b/lib/readline/doc/version.texi~ index 654e83777..42cc40360 100644 --- a/lib/readline/doc/version.texi~ +++ b/lib/readline/doc/version.texi~ @@ -4,7 +4,7 @@ Copyright (C) 1988-2006 Free Software Foundation, Inc. @set EDITION 5.2 @set VERSION 5.2 -@set UPDATED 26 April 2006 -@set UPDATED-MONTH April 2006 +@set UPDATED 30 December 2006 +@set UPDATED-MONTH December 2006 -@set LASTCHANGE Wed Apr 26 09:22:57 EDT 2006 +@set LASTCHANGE Sat Dec 30 19:17:22 EST 2006 diff --git a/lib/readline/histfile.c b/lib/readline/histfile.c index 5a782908d..a6e5f649b 100644 --- a/lib/readline/histfile.c +++ b/lib/readline/histfile.c @@ -53,6 +53,8 @@ # include #endif +#include + #if defined (__EMX__) # undef HAVE_MMAP #endif @@ -103,7 +105,7 @@ int history_write_timestamps = 0; /* Does S look like the beginning of a history timestamp entry? Placeholder for more extensive tests. */ -#define HIST_TIMESTAMP_START(s) (*(s) == history_comment_char) +#define HIST_TIMESTAMP_START(s) (*(s) == history_comment_char && isdigit ((s)[1]) ) /* Return the string that should be used in the place of this filename. This only matters when you don't specify the diff --git a/lib/readline/histfile.c~ b/lib/readline/histfile.c~ index 2f051a325..5a782908d 100644 --- a/lib/readline/histfile.c~ +++ b/lib/readline/histfile.c~ @@ -53,7 +53,7 @@ # include #endif -#if defined (__EMX__) || defined (__CYGWIN__) +#if defined (__EMX__) # undef HAVE_MMAP #endif diff --git a/pcomplete.c b/pcomplete.c index d250cd880..5873b30ec 100644 --- a/pcomplete.c +++ b/pcomplete.c @@ -1084,6 +1084,7 @@ gen_command_matches (cs, text, line, ind, lwords, nw, cw) char *csbuf, *cscmd, *t; int cmdlen, cmdsize, n, ws, we; WORD_LIST *cmdlist, *cl; + WORD_DESC *tw; STRINGLIST *sl; bind_compfunc_variables (line, ind, lwords, cw, 1); @@ -1115,7 +1116,9 @@ gen_command_matches (cs, text, line, ind, lwords, nw, cw) } cscmd[cmdlen] = '\0'; - csbuf = command_substitute (cscmd, 0); + tw = command_substitute (cscmd, 0); + csbuf = tw ? tw->word : (char *)NULL; + dispose_word_desc (tw); /* Now clean up and destroy everything. */ dispose_words (cmdlist); diff --git a/subst.c b/subst.c index fe95cdd94..4097fb612 100644 --- a/subst.c +++ b/subst.c @@ -216,7 +216,7 @@ static SHELL_VAR *do_compound_assignment __P((char *, char *, int)); #endif static int do_assignment_internal __P((const WORD_DESC *, int)); -static char *string_extract_verbatim __P((char *, size_t, int *, char *)); +static char *string_extract_verbatim __P((char *, size_t, int *, char *, int)); static char *string_extract __P((char *, int *, char *, int)); static char *string_extract_double_quoted __P((char *, int *, int)); static inline char *string_extract_single_quoted __P((char *, int *)); @@ -254,7 +254,7 @@ static char *parameter_brace_remove_pattern __P((char *, char *, char *, int, in static char *process_substitute __P((char *, int)); -static char *read_comsub __P((int, int)); +static char *read_comsub __P((int, int, int *)); #ifdef ARRAY_VARS static arrayind_t array_length_reference __P((char *)); @@ -886,11 +886,12 @@ skip_single_quoted (string, slen, sind) /* Just like string_extract, but doesn't hack backslashes or any of that other stuff. Obeys CTLESC quoting. Used to do splitting on $IFS. */ static char * -string_extract_verbatim (string, slen, sindex, charlist) +string_extract_verbatim (string, slen, sindex, charlist, flags) char *string; size_t slen; int *sindex; char *charlist; + int flags; { register int i = *sindex; #if defined (HANDLE_MULTIBYTE) @@ -1887,7 +1888,13 @@ string_list_dollar_at (list, quoted) sep[1] = '\0'; #endif + /* XXX -- why call quote_list if ifs == 0? we can get away without doing + it now that quote_escapes quotes spaces */ +#if 0 tlist = ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) || (ifs && *ifs == 0)) +#else + tlist = (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) +#endif ? quote_list (list) : list_quote_escapes (list); @@ -1973,7 +1980,7 @@ list_string (string, separators, quoted) { /* Don't need string length in ADVANCE_CHAR or string_extract_verbatim unless multibyte chars are possible. */ - current_word = string_extract_verbatim (string, slen, &sindex, separators); + current_word = string_extract_verbatim (string, slen, &sindex, separators, 0); if (current_word == 0) break; @@ -2096,7 +2103,7 @@ get_word_from_string (stringp, separators, endptr) /* Don't need string length in ADVANCE_CHAR or string_extract_verbatim unless multibyte chars are possible. */ slen = (MB_CUR_MAX > 1) ? strlen (s) : 1; - current_word = string_extract_verbatim (s, slen, &sindex, separators); + current_word = string_extract_verbatim (s, slen, &sindex, separators, 0); /* Set ENDPTR to the first character after the end of the word. */ if (endptr) @@ -2922,7 +2929,12 @@ expand_string (string, quoted) /* Quote escape characters in string s, but no other characters. This is used to protect CTLESC and CTLNUL in variable values from the rest of - the word expansion process after the variable is expanded. */ + the word expansion process after the variable is expanded. If IFS is + null, we quote spaces as well, just in case we split on spaces later + (in the case of unquoted $@, we will eventually attempt to split the + entire word on spaces). Corresponding code exists in dequote_escapes. + Even if we don't end up splitting on spaces, quoting spaces is not a + problem. */ char * quote_escapes (string) char *string; @@ -2930,17 +2942,19 @@ quote_escapes (string) register char *s, *t; size_t slen; char *result, *send; + int quote_spaces; DECLARE_MBSTATE; slen = strlen (string); send = string + slen; + quote_spaces = (ifs_value && *ifs_value == 0); t = result = (char *)xmalloc ((slen * 2) + 1); s = string; while (*s) { - if (*s == CTLESC || *s == CTLNUL) + if (*s == CTLESC || *s == CTLNUL || (quote_spaces && *s == ' ')) *t++ = CTLESC; COPY_CHAR_P (t, s, send); } @@ -2982,6 +2996,7 @@ dequote_escapes (string) register char *s, *t; size_t slen; char *result, *send; + int quote_spaces; DECLARE_MBSTATE; if (string == 0) @@ -2996,9 +3011,10 @@ dequote_escapes (string) if (strchr (string, CTLESC) == 0) return (strcpy (result, s)); + quote_spaces = (ifs_value && *ifs_value == 0); while (*s) { - if (*s == CTLESC && (s[1] == CTLESC || s[1] == CTLNUL)) + if (*s == CTLESC && (s[1] == CTLESC || s[1] == CTLNUL || (quote_spaces && s[1] == ' '))) { s++; if (*s == '\0') @@ -4129,6 +4145,12 @@ unlink_fifo_list () nfifo = 0; } +int +fifos_pending () +{ + return nfifo; +} + static char * make_named_pipe () { @@ -4178,6 +4200,12 @@ add_fifo_list (fd) nfds++; } +int +fifos_pending () +{ + return 0; /* used for cleanup; not needed with /dev/fd */ +} + void unlink_fifo_list () { @@ -4423,21 +4451,23 @@ process_substitute (string, open_for_read_in_child) /***********************************/ static char * -read_comsub (fd, quoted) +read_comsub (fd, quoted, rflag) int fd, quoted; + int *rflag; { char *istring, buf[128], *bufp; - int istring_index, istring_size, c; + int istring_index, istring_size, c, tflag; ssize_t bufn; istring = (char *)NULL; - istring_index = istring_size = bufn = 0; + istring_index = istring_size = bufn = tflag = 0; #ifdef __CYGWIN__ setmode (fd, O_TEXT); /* we don't want CR/LF, we want Unix-style */ #endif - /* Read the output of the command through the pipe. */ + /* Read the output of the command through the pipe. This may need to be + changed to understand multibyte characters in the future. */ while (1) { if (fd < 0) @@ -4462,7 +4492,18 @@ read_comsub (fd, quoted) /* Add the character to ISTRING, possibly after resizing it. */ RESIZE_MALLOCED_BUFFER (istring, istring_index, 2, istring_size, DEFAULT_ARRAY_SIZE); - if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) || c == CTLESC || c == CTLNUL) + /* This is essentially quote_string inline */ + if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) /* || c == CTLESC || c == CTLNUL */) + istring[istring_index++] = CTLESC; + /* Escape CTLESC and CTLNUL in the output to protect those characters + from the rest of the word expansions (word splitting and globbing.) + This is essentially quote_escapes inline. */ + else if (c == CTLESC) + { + tflag |= W_HASCTLESC; + istring[istring_index++] = CTLESC; + } + else if (c == CTLNUL || (c == ' ' && (ifs_value && *ifs_value == 0))) istring[istring_index++] = CTLESC; istring[istring_index++] = c; @@ -4486,6 +4527,8 @@ read_comsub (fd, quoted) if (istring_index == 0) { FREE (istring); + if (rflag) + *rflag = tflag; return (char *)NULL; } @@ -4510,26 +4553,29 @@ read_comsub (fd, quoted) else strip_trailing (istring, istring_index - 1, 1); + if (rflag) + *rflag = tflag; return istring; } -/* Perform command substitution on STRING. This returns a string, - possibly quoted. */ -char * +/* Perform command substitution on STRING. This returns a WORD_DESC * with the + contained string possibly quoted. */ +WORD_DESC * command_substitute (string, quoted) char *string; int quoted; { pid_t pid, old_pid, old_pipeline_pgrp, old_async_pid; char *istring; - int result, fildes[2], function_value, pflags, rc; + int result, fildes[2], function_value, pflags, rc, tflag; + WORD_DESC *ret; istring = (char *)NULL; /* Don't fork () if there is no need to. In the case of no command to run, just return NULL. */ if (!string || !*string || (string[0] == '\n' && !string[1])) - return ((char *)NULL); + return ((WORD_DESC *)NULL); if (wordexp_only && read_but_dont_execute) { @@ -4569,11 +4615,7 @@ command_substitute (string, quoted) #endif /* JOB_CONTROL */ old_async_pid = last_asynchronous_pid; -#if 0 - pid = make_child ((char *)NULL, 0); -#else pid = make_child ((char *)NULL, subshell_environment&SUBSHELL_ASYNC); -#endif last_asynchronous_pid = old_async_pid; if (pid == 0) @@ -4597,7 +4639,7 @@ command_substitute (string, quoted) FREE (istring); close (fildes[0]); close (fildes[1]); - return ((char *)NULL); + return ((WORD_DESC *)NULL); } if (pid == 0) @@ -4671,6 +4713,9 @@ command_substitute (string, quoted) last_command_exit_value = rc; rc = run_exit_trap (); +#if defined (PROCESS_SUBSTITUTION) + unlink_fifo_list (); +#endif exit (rc); } else @@ -4681,7 +4726,8 @@ command_substitute (string, quoted) close (fildes[1]); - istring = read_comsub (fildes[0], quoted); + tflag = 0; + istring = read_comsub (fildes[0], quoted, &tflag); close (fildes[0]); @@ -4711,7 +4757,11 @@ command_substitute (string, quoted) give_terminal_to (pipeline_pgrp, 0); #endif /* JOB_CONTROL */ - return (istring); + ret = alloc_word_desc (); + ret->word = istring; + ret->flags = tflag; + + return ret; } } @@ -4983,7 +5033,7 @@ parameter_brace_expand_rhs (name, value, c, quoted, qdollaratp, hasdollarat) /* If the entire expression is between double quotes, we want to treat the value as a double-quoted string, with the exception that we strip - embedded unescaped double quotes. */ + embedded unescaped double quotes (for sh backwards compatibility). */ if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) && *value) { hasdol = 0; @@ -5554,12 +5604,16 @@ parameter_brace_substring (varname, value, substr, quoted) so verify_substring_values just returns the numbers specified and we rely on array_subrange to understand how to deal with them). */ tt = array_subrange (array_cell (v), e1, e2, starsub, quoted); +#if 0 + /* array_subrange now calls array_quote_escapes as appropriate, so the + caller no longer needs to. */ if ((quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT)) == 0) { temp = tt ? quote_escapes (tt) : (char *)NULL; FREE (tt); } else +#endif temp = tt; break; #endif @@ -5810,12 +5864,16 @@ parameter_brace_patsub (varname, value, patsub, quoted) #if defined (ARRAY_VARS) case VT_ARRAYVAR: temp = array_patsub (array_cell (v), p, rep, mflags); +#if 0 + /* Don't need to do this anymore; array_patsub calls array_quote_escapes + as appropriate before adding the space separators. */ if (temp && (mflags & MATCH_QUOTED) == 0) { tt = quote_escapes (temp); free (temp); temp = tt; } +#endif break; #endif } @@ -6578,7 +6636,11 @@ comsub: /* we need zindex+1 because string[zindex] == RPAREN */ temp1 = substring (string, *sindex, zindex+1); else - temp1 = command_substitute (temp, quoted); + { + tdesc = command_substitute (temp, quoted); + temp1 = tdesc ? tdesc->word : (char *)NULL; + dispose_word_desc (tdesc); + } FREE (temp); temp = temp1; break; @@ -6986,7 +7048,9 @@ add_string: else { de_backslash (temp); - temp1 = command_substitute (temp, quoted); + tword = command_substitute (temp, quoted); + temp1 = tword ? tword->word : (char *)NULL; + dispose_word_desc (tword); } FREE (temp); temp = temp1; @@ -7512,11 +7576,7 @@ setifs (v) unsigned char uc; ifs_var = v; -#if 0 - ifs_value = v ? value_cell (v) : " \t\n"; -#else ifs_value = (v && value_cell (v)) ? value_cell (v) : " \t\n"; -#endif /* Should really merge ifs_cmap with sh_syntaxtab. XXX - doesn't yet handle multibyte chars in IFS */ diff --git a/subst.c.save1 b/subst.c.save1 new file mode 100644 index 000000000..11b146aa5 --- /dev/null +++ b/subst.c.save1 @@ -0,0 +1,8186 @@ +/* subst.c -- The part of the shell that does parameter, command, arithmetic, + and globbing substitutions. */ + +/* ``Have a little faith, there's magic in the night. You ain't a + beauty, but, hey, you're alright.'' */ + +/* Copyright (C) 1987-2006 Free Software Foundation, Inc. + + This file is part of GNU Bash, the Bourne Again SHell. + + Bash is free software; you can redistribute it and/or modify it under + the terms of the GNU General Public License as published by the Free + Software Foundation; either version 2, or (at your option) any later + version. + + Bash is distributed in the hope that it will be useful, but WITHOUT ANY + WARRANTY; without even the implied warranty of MERCHANTABILITY or + FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + for more details. + + You should have received a copy of the GNU General Public License along + with Bash; see the file COPYING. If not, write to the Free Software + Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA. */ + +#include "config.h" + +#include "bashtypes.h" +#include +#include "chartypes.h" +#include +#include +#include + +#if defined (HAVE_UNISTD_H) +# include +#endif + +#include "bashansi.h" +#include "posixstat.h" +#include "bashintl.h" + +#include "shell.h" +#include "flags.h" +#include "jobs.h" +#include "execute_cmd.h" +#include "filecntl.h" +#include "trap.h" +#include "pathexp.h" +#include "mailcheck.h" + +#include "shmbutil.h" + +#include "builtins/getopt.h" +#include "builtins/common.h" + +#include +#include + +#if !defined (errno) +extern int errno; +#endif /* !errno */ + +/* The size that strings change by. */ +#define DEFAULT_INITIAL_ARRAY_SIZE 112 +#define DEFAULT_ARRAY_SIZE 128 + +/* Variable types. */ +#define VT_VARIABLE 0 +#define VT_POSPARMS 1 +#define VT_ARRAYVAR 2 +#define VT_ARRAYMEMBER 3 + +#define VT_STARSUB 128 /* $* or ${array[*]} -- used to split */ + +/* Flags for quoted_strchr */ +#define ST_BACKSL 0x01 +#define ST_CTLESC 0x02 +#define ST_SQUOTE 0x04 /* unused yet */ +#define ST_DQUOTE 0x08 /* unused yet */ + +/* Flags for the string extraction functions. */ +#define EX_NOALLOC 0x01 /* just skip; don't return substring */ +#define EX_VARNAME 0x02 /* variable name; for string_extract () */ +#define EX_REQMATCH 0x04 /* closing/matching delimiter required */ +#define EX_COMMAND 0x08 /* extracting a shell script/command */ + +/* Flags for the `pflags' argument to param_expand() */ +#define PF_NOCOMSUB 0x01 /* Do not perform command substitution */ + +/* These defs make it easier to use the editor. */ +#define LBRACE '{' +#define RBRACE '}' +#define LPAREN '(' +#define RPAREN ')' + +/* Evaluates to 1 if C is one of the shell's special parameters whose length + can be taken, but is also one of the special expansion characters. */ +#define VALID_SPECIAL_LENGTH_PARAM(c) \ + ((c) == '-' || (c) == '?' || (c) == '#') + +/* Evaluates to 1 if C is one of the shell's special parameters for which an + indirect variable reference may be made. */ +#define VALID_INDIR_PARAM(c) \ + ((c) == '#' || (c) == '?' || (c) == '@' || (c) == '*') + +/* Evaluates to 1 if C is one of the OP characters that follows the parameter + in ${parameter[:]OPword}. */ +#define VALID_PARAM_EXPAND_CHAR(c) (sh_syntaxtab[(unsigned char)c] & CSUBSTOP) + +/* Evaluates to 1 if this is one of the shell's special variables. */ +#define SPECIAL_VAR(name, wi) \ + ((DIGIT (*name) && all_digits (name)) || \ + (name[1] == '\0' && (sh_syntaxtab[(unsigned char)*name] & CSPECVAR)) || \ + (wi && name[2] == '\0' && VALID_INDIR_PARAM (name[1]))) + +/* An expansion function that takes a string and a quoted flag and returns + a WORD_LIST *. Used as the type of the third argument to + expand_string_if_necessary(). */ +typedef WORD_LIST *EXPFUNC __P((char *, int)); + +/* Process ID of the last command executed within command substitution. */ +pid_t last_command_subst_pid = NO_PID; +pid_t current_command_subst_pid = NO_PID; + +/* Variables used to keep track of the characters in IFS. */ +SHELL_VAR *ifs_var; +char *ifs_value; +unsigned char ifs_cmap[UCHAR_MAX + 1]; + +#if defined (HANDLE_MULTIBYTE) +unsigned char ifs_firstc[MB_LEN_MAX]; +size_t ifs_firstc_len; +#else +unsigned char ifs_firstc; +#endif + +/* Extern functions and variables from different files. */ +extern int last_command_exit_value, last_command_exit_signal; +extern int subshell_environment; +extern int subshell_level; +extern int eof_encountered; +extern int return_catch_flag, return_catch_value; +extern pid_t dollar_dollar_pid; +extern int posixly_correct; +extern char *this_command_name; +extern struct fd_bitmap *current_fds_to_close; +extern int wordexp_only; +extern int expanding_redir; +extern int tempenv_assign_error; + +#if !defined (HAVE_WCSDUP) && defined (HANDLE_MULTIBYTE) +extern wchar_t *wcsdup __P((const wchar_t *)); +#endif + +/* Non-zero means to allow unmatched globbed filenames to expand to + a null file. */ +int allow_null_glob_expansion; + +/* Non-zero means to throw an error when globbing fails to match anything. */ +int fail_glob_expansion; + +#if 0 +/* Variables to keep track of which words in an expanded word list (the + output of expand_word_list_internal) are the result of globbing + expansions. GLOB_ARGV_FLAGS is used by execute_cmd.c. + (CURRENTLY UNUSED). */ +char *glob_argv_flags; +static int glob_argv_flags_size; +#endif + +static WORD_LIST expand_word_error, expand_word_fatal; +static WORD_DESC expand_wdesc_error, expand_wdesc_fatal; +static char expand_param_error, expand_param_fatal; +static char extract_string_error, extract_string_fatal; + +/* Tell the expansion functions to not longjmp back to top_level on fatal + errors. Enabled when doing completion and prompt string expansion. */ +static int no_longjmp_on_fatal_error = 0; + +/* Set by expand_word_unsplit; used to inhibit splitting and re-joining + $* on $IFS, primarily when doing assignment statements. */ +static int expand_no_split_dollar_star = 0; + +/* Used to hold a list of variable assignments preceding a command. Global + so the SIGCHLD handler in jobs.c can unwind-protect it when it runs a + SIGCHLD trap. */ +WORD_LIST *subst_assign_varlist = (WORD_LIST *)NULL; + +/* A WORD_LIST of words to be expanded by expand_word_list_internal, + without any leading variable assignments. */ +static WORD_LIST *garglist = (WORD_LIST *)NULL; + +static char *quoted_substring __P((char *, int, int)); +static int quoted_strlen __P((char *)); +static char *quoted_strchr __P((char *, int, int)); + +static char *expand_string_if_necessary __P((char *, int, EXPFUNC *)); +static inline char *expand_string_to_string_internal __P((char *, int, EXPFUNC *)); +static WORD_LIST *call_expand_word_internal __P((WORD_DESC *, int, int, int *, int *)); +static WORD_LIST *expand_string_internal __P((char *, int)); +static WORD_LIST *expand_string_leave_quoted __P((char *, int)); +static WORD_LIST *expand_string_for_rhs __P((char *, int, int *, int *)); + +static WORD_LIST *list_quote_escapes __P((WORD_LIST *)); +static char *dequote_escapes __P((char *)); +static char *make_quoted_char __P((int)); +static WORD_LIST *quote_list __P((WORD_LIST *)); +static char *remove_quoted_escapes __P((char *)); +static char *remove_quoted_nulls __P((char *)); + +static int unquoted_substring __P((char *, char *)); +static int unquoted_member __P((int, char *)); + +#if defined (ARRAY_VARS) +static SHELL_VAR *do_compound_assignment __P((char *, char *, int)); +#endif +static int do_assignment_internal __P((const WORD_DESC *, int)); + +static char *string_extract_verbatim __P((char *, size_t, int *, char *, int)); +static char *string_extract __P((char *, int *, char *, int)); +static char *string_extract_double_quoted __P((char *, int *, int)); +static inline char *string_extract_single_quoted __P((char *, int *)); +static inline int skip_single_quoted __P((const char *, size_t, int)); +static int skip_double_quoted __P((char *, size_t, int)); +static char *extract_delimited_string __P((char *, int *, char *, char *, char *, int)); +static char *extract_dollar_brace_string __P((char *, int *, int, int)); + +static char *pos_params __P((char *, int, int, int)); + +static unsigned char *mb_getcharlens __P((char *, int)); + +static char *remove_upattern __P((char *, char *, int)); +#if defined (HANDLE_MULTIBYTE) +static wchar_t *remove_wpattern __P((wchar_t *, size_t, wchar_t *, int)); +#endif +static char *remove_pattern __P((char *, char *, int)); + +static int match_pattern_char __P((char *, char *)); +static int match_upattern __P((char *, char *, int, char **, char **)); +#if defined (HANDLE_MULTIBYTE) +static int match_pattern_wchar __P((wchar_t *, wchar_t *)); +static int match_wpattern __P((wchar_t *, char **, size_t, wchar_t *, int, char **, char **)); +#endif +static int match_pattern __P((char *, char *, int, char **, char **)); +static int getpatspec __P((int, char *)); +static char *getpattern __P((char *, int, int)); +static char *variable_remove_pattern __P((char *, char *, int, int)); +static char *list_remove_pattern __P((WORD_LIST *, char *, int, int, int)); +static char *parameter_list_remove_pattern __P((int, char *, int, int)); +#ifdef ARRAY_VARS +static char *array_remove_pattern __P((ARRAY *, char *, int, char *, int)); +#endif +static char *parameter_brace_remove_pattern __P((char *, char *, char *, int, int)); + +static char *process_substitute __P((char *, int)); + +static char *read_comsub __P((int, int, int *)); + +#ifdef ARRAY_VARS +static arrayind_t array_length_reference __P((char *)); +#endif + +static int valid_brace_expansion_word __P((char *, int)); +static int chk_atstar __P((char *, int, int *, int *)); +static int chk_arithsub __P((const char *, int)); + +static WORD_DESC *parameter_brace_expand_word __P((char *, int, int)); +static WORD_DESC *parameter_brace_expand_indir __P((char *, int, int, int *, int *)); +static WORD_DESC *parameter_brace_expand_rhs __P((char *, char *, int, int, int *, int *)); +static void parameter_brace_expand_error __P((char *, char *)); + +static int valid_length_expression __P((char *)); +static intmax_t parameter_brace_expand_length __P((char *)); + +static char *skiparith __P((char *, int)); +static int verify_substring_values __P((char *, char *, int, intmax_t *, intmax_t *)); +static int get_var_and_type __P((char *, char *, int, SHELL_VAR **, char **)); +static char *mb_substring __P((char *, int, int)); +static char *parameter_brace_substring __P((char *, char *, char *, int)); + +static char *pos_params_pat_subst __P((char *, char *, char *, int)); + +static char *parameter_brace_patsub __P((char *, char *, char *, int)); + +static WORD_DESC *parameter_brace_expand __P((char *, int *, int, int *, int *)); +static WORD_DESC *param_expand __P((char *, int *, int, int *, int *, int *, int *, int)); + +static WORD_LIST *expand_word_internal __P((WORD_DESC *, int, int, int *, int *)); + +static WORD_LIST *word_list_split __P((WORD_LIST *)); + +static void exp_jump_to_top_level __P((int)); + +static WORD_LIST *separate_out_assignments __P((WORD_LIST *)); +static WORD_LIST *glob_expand_word_list __P((WORD_LIST *, int)); +#ifdef BRACE_EXPANSION +static WORD_LIST *brace_expand_word_list __P((WORD_LIST *, int)); +#endif +static WORD_LIST *shell_expand_word_list __P((WORD_LIST *, int)); +static WORD_LIST *expand_word_list_internal __P((WORD_LIST *, int)); + +/* **************************************************************** */ +/* */ +/* Utility Functions */ +/* */ +/* **************************************************************** */ + +#ifdef INCLUDE_UNUSED +static char * +quoted_substring (string, start, end) + char *string; + int start, end; +{ + register int len, l; + register char *result, *s, *r; + + len = end - start; + + /* Move to string[start], skipping quoted characters. */ + for (s = string, l = 0; *s && l < start; ) + { + if (*s == CTLESC) + { + s++; + continue; + } + l++; + if (*s == 0) + break; + } + + r = result = (char *)xmalloc (2*len + 1); /* save room for quotes */ + + /* Copy LEN characters, including quote characters. */ + s = string + l; + for (l = 0; l < len; s++) + { + if (*s == CTLESC) + *r++ = *s++; + *r++ = *s; + l++; + if (*s == 0) + break; + } + *r = '\0'; + return result; +} +#endif + +#ifdef INCLUDE_UNUSED +/* Return the length of S, skipping over quoted characters */ +static int +quoted_strlen (s) + char *s; +{ + register char *p; + int i; + + i = 0; + for (p = s; *p; p++) + { + if (*p == CTLESC) + { + p++; + if (*p == 0) + return (i + 1); + } + i++; + } + + return i; +} +#endif + +/* Find the first occurrence of character C in string S, obeying shell + quoting rules. If (FLAGS & ST_BACKSL) is non-zero, backslash-escaped + characters are skipped. If (FLAGS & ST_CTLESC) is non-zero, characters + escaped with CTLESC are skipped. */ +static char * +quoted_strchr (s, c, flags) + char *s; + int c, flags; +{ + register char *p; + + for (p = s; *p; p++) + { + if (((flags & ST_BACKSL) && *p == '\\') + || ((flags & ST_CTLESC) && *p == CTLESC)) + { + p++; + if (*p == '\0') + return ((char *)NULL); + continue; + } + else if (*p == c) + return p; + } + return ((char *)NULL); +} + +/* Return 1 if CHARACTER appears in an unquoted portion of + STRING. Return 0 otherwise. CHARACTER must be a single-byte character. */ +static int +unquoted_member (character, string) + int character; + char *string; +{ + size_t slen; + int sindex, c; + DECLARE_MBSTATE; + + slen = strlen (string); + sindex = 0; + while (c = string[sindex]) + { + if (c == character) + return (1); + + switch (c) + { + default: + ADVANCE_CHAR (string, slen, sindex); + break; + + case '\\': + sindex++; + if (string[sindex]) + ADVANCE_CHAR (string, slen, sindex); + break; + + case '\'': + sindex = skip_single_quoted (string, slen, ++sindex); + break; + + case '"': + sindex = skip_double_quoted (string, slen, ++sindex); + break; + } + } + return (0); +} + +/* Return 1 if SUBSTR appears in an unquoted portion of STRING. */ +static int +unquoted_substring (substr, string) + char *substr, *string; +{ + size_t slen; + int sindex, c, sublen; + DECLARE_MBSTATE; + + if (substr == 0 || *substr == '\0') + return (0); + + slen = strlen (string); + sublen = strlen (substr); + for (sindex = 0; c = string[sindex]; ) + { + if (STREQN (string + sindex, substr, sublen)) + return (1); + + switch (c) + { + case '\\': + sindex++; + + if (string[sindex]) + ADVANCE_CHAR (string, slen, sindex); + break; + + case '\'': + sindex = skip_single_quoted (string, slen, ++sindex); + break; + + case '"': + sindex = skip_double_quoted (string, slen, ++sindex); + break; + + default: + ADVANCE_CHAR (string, slen, sindex); + break; + } + } + return (0); +} + +/* Most of the substitutions must be done in parallel. In order + to avoid using tons of unclear goto's, I have some functions + for manipulating malloc'ed strings. They all take INDX, a + pointer to an integer which is the offset into the string + where manipulation is taking place. They also take SIZE, a + pointer to an integer which is the current length of the + character array for this string. */ + +/* Append SOURCE to TARGET at INDEX. SIZE is the current amount + of space allocated to TARGET. SOURCE can be NULL, in which + case nothing happens. Gets rid of SOURCE by freeing it. + Returns TARGET in case the location has changed. */ +INLINE char * +sub_append_string (source, target, indx, size) + char *source, *target; + int *indx, *size; +{ + if (source) + { + int srclen, n; + + srclen = STRLEN (source); + if (srclen >= (int)(*size - *indx)) + { + n = srclen + *indx; + n = (n + DEFAULT_ARRAY_SIZE) - (n % DEFAULT_ARRAY_SIZE); + target = (char *)xrealloc (target, (*size = n)); + } + + FASTCOPY (source, target + *indx, srclen); + *indx += srclen; + target[*indx] = '\0'; + + free (source); + } + return (target); +} + +#if 0 +/* UNUSED */ +/* Append the textual representation of NUMBER to TARGET. + INDX and SIZE are as in SUB_APPEND_STRING. */ +char * +sub_append_number (number, target, indx, size) + intmax_t number; + int *indx, *size; + char *target; +{ + char *temp; + + temp = itos (number); + return (sub_append_string (temp, target, indx, size)); +} +#endif + +/* Extract a substring from STRING, starting at SINDEX and ending with + one of the characters in CHARLIST. Don't make the ending character + part of the string. Leave SINDEX pointing at the ending character. + Understand about backslashes in the string. If (flags & EX_VARNAME) + is non-zero, and array variables have been compiled into the shell, + everything between a `[' and a corresponding `]' is skipped over. + If (flags & EX_NOALLOC) is non-zero, don't return the substring, just + update SINDEX. If (flags & EX_REQMATCH) is non-zero, the string must + contain a closing character from CHARLIST. */ +static char * +string_extract (string, sindex, charlist, flags) + char *string; + int *sindex; + char *charlist; + int flags; +{ + register int c, i; + int found; + size_t slen; + char *temp; + DECLARE_MBSTATE; + + slen = (MB_CUR_MAX > 1) ? strlen (string + *sindex) + *sindex : 0; + i = *sindex; + found = 0; + while (c = string[i]) + { + if (c == '\\') + { + if (string[i + 1]) + i++; + else + break; + } +#if defined (ARRAY_VARS) + else if ((flags & EX_VARNAME) && c == '[') + { + int ni; + /* If this is an array subscript, skip over it and continue. */ + ni = skipsubscript (string, i); + if (string[ni] == ']') + i = ni; + } +#endif + else if (MEMBER (c, charlist)) + { + found = 1; + break; + } + + ADVANCE_CHAR (string, slen, i); + } + + /* If we had to have a matching delimiter and didn't find one, return an + error and let the caller deal with it. */ + if ((flags & EX_REQMATCH) && found == 0) + { + *sindex = i; + return (&extract_string_error); + } + + temp = (flags & EX_NOALLOC) ? (char *)NULL : substring (string, *sindex, i); + *sindex = i; + + return (temp); +} + +/* Extract the contents of STRING as if it is enclosed in double quotes. + SINDEX, when passed in, is the offset of the character immediately + following the opening double quote; on exit, SINDEX is left pointing after + the closing double quote. If STRIPDQ is non-zero, unquoted double + quotes are stripped and the string is terminated by a null byte. + Backslashes between the embedded double quotes are processed. If STRIPDQ + is zero, an unquoted `"' terminates the string. */ +static char * +string_extract_double_quoted (string, sindex, stripdq) + char *string; + int *sindex, stripdq; +{ + size_t slen; + char *send; + int j, i, t; + unsigned char c; + char *temp, *ret; /* The new string we return. */ + int pass_next, backquote, si; /* State variables for the machine. */ + int dquote; + DECLARE_MBSTATE; + + slen = strlen (string + *sindex) + *sindex; + send = string + slen; + + pass_next = backquote = dquote = 0; + temp = (char *)xmalloc (1 + slen - *sindex); + + j = 0; + i = *sindex; + while (c = string[i]) + { + /* Process a character that was quoted by a backslash. */ + if (pass_next) + { + /* Posix.2 sez: + + ``The backslash shall retain its special meaning as an escape + character only when followed by one of the characters: + $ ` " \ ''. + + If STRIPDQ is zero, we handle the double quotes here and let + expand_word_internal handle the rest. If STRIPDQ is non-zero, + we have already been through one round of backslash stripping, + and want to strip these backslashes only if DQUOTE is non-zero, + indicating that we are inside an embedded double-quoted string. */ + + /* If we are in an embedded quoted string, then don't strip + backslashes before characters for which the backslash + retains its special meaning, but remove backslashes in + front of other characters. If we are not in an + embedded quoted string, don't strip backslashes at all. + This mess is necessary because the string was already + surrounded by double quotes (and sh has some really weird + quoting rules). + The returned string will be run through expansion as if + it were double-quoted. */ + if ((stripdq == 0 && c != '"') || + (stripdq && ((dquote && (sh_syntaxtab[c] & CBSDQUOTE)) || dquote == 0))) + temp[j++] = '\\'; + pass_next = 0; + +add_one_character: + COPY_CHAR_I (temp, j, string, send, i); + continue; + } + + /* A backslash protects the next character. The code just above + handles preserving the backslash in front of any character but + a double quote. */ + if (c == '\\') + { + pass_next++; + i++; + continue; + } + + /* Inside backquotes, ``the portion of the quoted string from the + initial backquote and the characters up to the next backquote + that is not preceded by a backslash, having escape characters + removed, defines that command''. */ + if (backquote) + { + if (c == '`') + backquote = 0; + temp[j++] = c; + i++; + continue; + } + + if (c == '`') + { + temp[j++] = c; + backquote++; + i++; + continue; + } + + /* Pass everything between `$(' and the matching `)' or a quoted + ${ ... } pair through according to the Posix.2 specification. */ + if (c == '$' && ((string[i + 1] == LPAREN) || (string[i + 1] == LBRACE))) + { + int free_ret = 1; + + si = i + 2; + if (string[i + 1] == LPAREN) + ret = extract_delimited_string (string, &si, "$(", "(", ")", EX_COMMAND); /*)*/ + else + ret = extract_dollar_brace_string (string, &si, 1, 0); + + temp[j++] = '$'; + temp[j++] = string[i + 1]; + + /* Just paranoia; ret will not be 0 unless no_longjmp_on_fatal_error + is set. */ + if (ret == 0 && no_longjmp_on_fatal_error) + { + free_ret = 0; + ret = string + i + 2; + } + + for (t = 0; ret[t]; t++, j++) + temp[j] = ret[t]; + temp[j] = string[si]; + + if (string[si]) + { + j++; + i = si + 1; + } + else + i = si; + + if (free_ret) + free (ret); + continue; + } + + /* Add any character but a double quote to the quoted string we're + accumulating. */ + if (c != '"') + goto add_one_character; + + /* c == '"' */ + if (stripdq) + { + dquote ^= 1; + i++; + continue; + } + + break; + } + temp[j] = '\0'; + + /* Point to after the closing quote. */ + if (c) + i++; + *sindex = i; + + return (temp); +} + +/* This should really be another option to string_extract_double_quoted. */ +static int +skip_double_quoted (string, slen, sind) + char *string; + size_t slen; + int sind; +{ + int c, i; + char *ret; + int pass_next, backquote, si; + DECLARE_MBSTATE; + + pass_next = backquote = 0; + i = sind; + while (c = string[i]) + { + if (pass_next) + { + pass_next = 0; + ADVANCE_CHAR (string, slen, i); + continue; + } + else if (c == '\\') + { + pass_next++; + i++; + continue; + } + else if (backquote) + { + if (c == '`') + backquote = 0; + ADVANCE_CHAR (string, slen, i); + continue; + } + else if (c == '`') + { + backquote++; + i++; + continue; + } + else if (c == '$' && ((string[i + 1] == LPAREN) || (string[i + 1] == LBRACE))) + { + si = i + 2; + if (string[i + 1] == LPAREN) + ret = extract_delimited_string (string, &si, "$(", "(", ")", EX_NOALLOC|EX_COMMAND); /* ) */ + else + ret = extract_dollar_brace_string (string, &si, 0, EX_NOALLOC); + + i = si + 1; + continue; + } + else if (c != '"') + { + ADVANCE_CHAR (string, slen, i); + continue; + } + else + break; + } + + if (c) + i++; + + return (i); +} + +/* Extract the contents of STRING as if it is enclosed in single quotes. + SINDEX, when passed in, is the offset of the character immediately + following the opening single quote; on exit, SINDEX is left pointing after + the closing single quote. */ +static inline char * +string_extract_single_quoted (string, sindex) + char *string; + int *sindex; +{ + register int i; + size_t slen; + char *t; + DECLARE_MBSTATE; + + /* Don't need slen for ADVANCE_CHAR unless multibyte chars possible. */ + slen = (MB_CUR_MAX > 1) ? strlen (string + *sindex) + *sindex : 0; + i = *sindex; + while (string[i] && string[i] != '\'') + ADVANCE_CHAR (string, slen, i); + + t = substring (string, *sindex, i); + + if (string[i]) + i++; + *sindex = i; + + return (t); +} + +static inline int +skip_single_quoted (string, slen, sind) + const char *string; + size_t slen; + int sind; +{ + register int c; + DECLARE_MBSTATE; + + c = sind; + while (string[c] && string[c] != '\'') + ADVANCE_CHAR (string, slen, c); + + if (string[c]) + c++; + return c; +} + +/* Just like string_extract, but doesn't hack backslashes or any of + that other stuff. Obeys CTLESC quoting. Used to do splitting on $IFS. */ +static char * +string_extract_verbatim (string, slen, sindex, charlist, flags) + char *string; + size_t slen; + int *sindex; + char *charlist; + int flags; +{ + register int i = *sindex; +#if defined (HANDLE_MULTIBYTE) + size_t clen; + wchar_t *wcharlist; +#endif + int c; + char *temp; + DECLARE_MBSTATE; + + if (charlist[0] == '\'' && charlist[1] == '\0') + { + temp = string_extract_single_quoted (string, sindex); + --*sindex; /* leave *sindex at separator character */ + return temp; + } + + i = *sindex; +#if 0 + /* See how the MBLEN and ADVANCE_CHAR macros work to understand why we need + this only if MB_CUR_MAX > 1. */ + slen = (MB_CUR_MAX > 1) ? strlen (string + *sindex) + *sindex : 1; +#endif +#if defined (HANDLE_MULTIBYTE) + clen = strlen (charlist); + wcharlist = 0; +#endif + while (c = string[i]) + { +#if defined (HANDLE_MULTIBYTE) + size_t mblength; +#endif + if (c == CTLESC) + { + i += 2; + continue; + } + +#if defined (HANDLE_MULTIBYTE) + mblength = MBLEN (string + i, slen - i); + if (mblength > 1) + { + wchar_t wc; + mblength = mbtowc (&wc, string + i, slen - i); + if (MB_INVALIDCH (mblength)) + { + if (MEMBER (c, charlist)) + break; + } + else + { + if (wcharlist == 0) + { + size_t len; + len = mbstowcs (wcharlist, charlist, 0); + if (len == -1) + len = 0; + wcharlist = (wchar_t *)xmalloc (sizeof (wchar_t) * (len + 1)); + mbstowcs (wcharlist, charlist, len + 1); + } + + if (wcschr (wcharlist, wc)) + break; + } + } + else +#endif + if (MEMBER (c, charlist)) + break; + + ADVANCE_CHAR (string, slen, i); + } + +#if defined (HANDLE_MULTIBYTE) + FREE (wcharlist); +#endif + + temp = substring (string, *sindex, i); + *sindex = i; + + return (temp); +} + +/* Extract the $( construct in STRING, and return a new string. + Start extracting at (SINDEX) as if we had just seen "$(". + Make (SINDEX) get the position of the matching ")". ) */ +char * +extract_command_subst (string, sindex) + char *string; + int *sindex; +{ + return (extract_delimited_string (string, sindex, "$(", "(", ")", EX_COMMAND)); /*)*/ +} + +/* Extract the $[ construct in STRING, and return a new string. (]) + Start extracting at (SINDEX) as if we had just seen "$[". + Make (SINDEX) get the position of the matching "]". */ +char * +extract_arithmetic_subst (string, sindex) + char *string; + int *sindex; +{ + return (extract_delimited_string (string, sindex, "$[", "[", "]", 0)); /*]*/ +} + +#if defined (PROCESS_SUBSTITUTION) +/* Extract the <( or >( construct in STRING, and return a new string. + Start extracting at (SINDEX) as if we had just seen "<(". + Make (SINDEX) get the position of the matching ")". */ /*))*/ +char * +extract_process_subst (string, starter, sindex) + char *string; + char *starter; + int *sindex; +{ + return (extract_delimited_string (string, sindex, starter, "(", ")", 0)); +} +#endif /* PROCESS_SUBSTITUTION */ + +#if defined (ARRAY_VARS) +/* This can be fooled by unquoted right parens in the passed string. If + each caller verifies that the last character in STRING is a right paren, + we don't even need to call extract_delimited_string. */ +char * +extract_array_assignment_list (string, sindex) + char *string; + int *sindex; +{ + int slen; + char *ret; + + slen = strlen (string); /* ( */ + if (string[slen - 1] == ')') + { + ret = substring (string, *sindex, slen - 1); + *sindex = slen - 1; + return ret; + } + return 0; +} +#endif + +/* Extract and create a new string from the contents of STRING, a + character string delimited with OPENER and CLOSER. SINDEX is + the address of an int describing the current offset in STRING; + it should point to just after the first OPENER found. On exit, + SINDEX gets the position of the last character of the matching CLOSER. + If OPENER is more than a single character, ALT_OPENER, if non-null, + contains a character string that can also match CLOSER and thus + needs to be skipped. */ +static char * +extract_delimited_string (string, sindex, opener, alt_opener, closer, flags) + char *string; + int *sindex; + char *opener, *alt_opener, *closer; + int flags; +{ + int i, c, si; + size_t slen; + char *t, *result; + int pass_character, nesting_level, in_comment; + int len_closer, len_opener, len_alt_opener; + DECLARE_MBSTATE; + + slen = strlen (string + *sindex) + *sindex; + len_opener = STRLEN (opener); + len_alt_opener = STRLEN (alt_opener); + len_closer = STRLEN (closer); + + pass_character = in_comment = 0; + + nesting_level = 1; + i = *sindex; + + while (nesting_level) + { + c = string[i]; + + if (c == 0) + break; + + if (in_comment) + { + if (c == '\n') + in_comment = 0; + ADVANCE_CHAR (string, slen, i); + continue; + } + + if (pass_character) /* previous char was backslash */ + { + pass_character = 0; + ADVANCE_CHAR (string, slen, i); + continue; + } + + /* Not exactly right yet; should handle shell metacharacters and + multibyte characters, too. */ + if ((flags & EX_COMMAND) && c == '#' && (i == 0 || string[i - 1] == '\n' || whitespace (string[i - 1]))) + { + in_comment = 1; + ADVANCE_CHAR (string, slen, i); + continue; + } + + if (c == CTLESC || c == '\\') + { + pass_character++; + i++; + continue; + } + + /* Process a nested OPENER. */ + if (STREQN (string + i, opener, len_opener)) + { + si = i + len_opener; + t = extract_delimited_string (string, &si, opener, alt_opener, closer, flags|EX_NOALLOC); + i = si + 1; + continue; + } + + /* Process a nested ALT_OPENER */ + if (len_alt_opener && STREQN (string + i, alt_opener, len_alt_opener)) + { + si = i + len_alt_opener; + t = extract_delimited_string (string, &si, alt_opener, alt_opener, closer, flags|EX_NOALLOC); + i = si + 1; + continue; + } + + /* If the current substring terminates the delimited string, decrement + the nesting level. */ + if (STREQN (string + i, closer, len_closer)) + { + i += len_closer - 1; /* move to last byte of the closer */ + nesting_level--; + if (nesting_level == 0) + break; + } + + /* Pass old-style command substitution through verbatim. */ + if (c == '`') + { + si = i + 1; + t = string_extract (string, &si, "`", flags|EX_NOALLOC); + i = si + 1; + continue; + } + + /* Pass single-quoted and double-quoted strings through verbatim. */ + if (c == '\'' || c == '"') + { + si = i + 1; + i = (c == '\'') ? skip_single_quoted (string, slen, si) + : skip_double_quoted (string, slen, si); + continue; + } + + /* move past this character, which was not special. */ + ADVANCE_CHAR (string, slen, i); + } + + if (c == 0 && nesting_level) + { + if (no_longjmp_on_fatal_error == 0) + { + report_error (_("bad substitution: no closing `%s' in %s"), closer, string); + last_command_exit_value = EXECUTION_FAILURE; + exp_jump_to_top_level (DISCARD); + } + else + { + *sindex = i; + return (char *)NULL; + } + } + + si = i - *sindex - len_closer + 1; + if (flags & EX_NOALLOC) + result = (char *)NULL; + else + { + result = (char *)xmalloc (1 + si); + strncpy (result, string + *sindex, si); + result[si] = '\0'; + } + *sindex = i; + + return (result); +} + +/* Extract a parameter expansion expression within ${ and } from STRING. + Obey the Posix.2 rules for finding the ending `}': count braces while + skipping over enclosed quoted strings and command substitutions. + SINDEX is the address of an int describing the current offset in STRING; + it should point to just after the first `{' found. On exit, SINDEX + gets the position of the matching `}'. QUOTED is non-zero if this + occurs inside double quotes. */ +/* XXX -- this is very similar to extract_delimited_string -- XXX */ +static char * +extract_dollar_brace_string (string, sindex, quoted, flags) + char *string; + int *sindex, quoted, flags; +{ + register int i, c; + size_t slen; + int pass_character, nesting_level, si; + char *result, *t; + DECLARE_MBSTATE; + + pass_character = 0; + nesting_level = 1; + slen = strlen (string + *sindex) + *sindex; + + i = *sindex; + while (c = string[i]) + { + if (pass_character) + { + pass_character = 0; + ADVANCE_CHAR (string, slen, i); + continue; + } + + /* CTLESCs and backslashes quote the next character. */ + if (c == CTLESC || c == '\\') + { + pass_character++; + i++; + continue; + } + + if (string[i] == '$' && string[i+1] == LBRACE) + { + nesting_level++; + i += 2; + continue; + } + + if (c == RBRACE) + { + nesting_level--; + if (nesting_level == 0) + break; + i++; + continue; + } + + /* Pass the contents of old-style command substitutions through + verbatim. */ + if (c == '`') + { + si = i + 1; + t = string_extract (string, &si, "`", flags|EX_NOALLOC); + i = si + 1; + continue; + } + + /* Pass the contents of new-style command substitutions and + arithmetic substitutions through verbatim. */ + if (string[i] == '$' && string[i+1] == LPAREN) + { + si = i + 2; + t = extract_delimited_string (string, &si, "$(", "(", ")", flags|EX_NOALLOC|EX_COMMAND); /*)*/ + i = si + 1; + continue; + } + + /* Pass the contents of single-quoted and double-quoted strings + through verbatim. */ + if (c == '\'' || c == '"') + { + si = i + 1; + i = (c == '\'') ? skip_single_quoted (string, slen, si) + : skip_double_quoted (string, slen, si); + /* skip_XXX_quoted leaves index one past close quote */ + continue; + } + + /* move past this character, which was not special. */ + ADVANCE_CHAR (string, slen, i); + } + + if (c == 0 && nesting_level) + { + if (no_longjmp_on_fatal_error == 0) + { /* { */ + report_error (_("bad substitution: no closing `%s' in %s"), "}", string); + last_command_exit_value = EXECUTION_FAILURE; + exp_jump_to_top_level (DISCARD); + } + else + { + *sindex = i; + return ((char *)NULL); + } + } + + result = (flags & EX_NOALLOC) ? (char *)NULL : substring (string, *sindex, i); + *sindex = i; + + return (result); +} + +/* Remove backslashes which are quoting backquotes from STRING. Modifies + STRING, and returns a pointer to it. */ +char * +de_backslash (string) + char *string; +{ + register size_t slen; + register int i, j, prev_i; + DECLARE_MBSTATE; + + slen = strlen (string); + i = j = 0; + + /* Loop copying string[i] to string[j], i >= j. */ + while (i < slen) + { + if (string[i] == '\\' && (string[i + 1] == '`' || string[i + 1] == '\\' || + string[i + 1] == '$')) + i++; + prev_i = i; + ADVANCE_CHAR (string, slen, i); + if (j < prev_i) + do string[j++] = string[prev_i++]; while (prev_i < i); + else + j = i; + } + string[j] = '\0'; + + return (string); +} + +#if 0 +/*UNUSED*/ +/* Replace instances of \! in a string with !. */ +void +unquote_bang (string) + char *string; +{ + register int i, j; + register char *temp; + + temp = (char *)xmalloc (1 + strlen (string)); + + for (i = 0, j = 0; (temp[j] = string[i]); i++, j++) + { + if (string[i] == '\\' && string[i + 1] == '!') + { + temp[j] = '!'; + i++; + } + } + strcpy (string, temp); + free (temp); +} +#endif + +#if defined (READLINE) +/* Return 1 if the portion of STRING ending at EINDEX is quoted (there is + an unclosed quoted string), or if the character at EINDEX is quoted + by a backslash. NO_LONGJMP_ON_FATAL_ERROR is used to flag that the various + single and double-quoted string parsing functions should not return an + error if there are unclosed quotes or braces. The characters that this + recognizes need to be the same as the contents of + rl_completer_quote_characters. */ + +#define CQ_RETURN(x) do { no_longjmp_on_fatal_error = 0; return (x); } while (0) + +int +char_is_quoted (string, eindex) + char *string; + int eindex; +{ + int i, pass_next, c; + size_t slen; + DECLARE_MBSTATE; + + slen = strlen (string); + no_longjmp_on_fatal_error = 1; + i = pass_next = 0; + while (i <= eindex) + { + c = string[i]; + + if (pass_next) + { + pass_next = 0; + if (i >= eindex) /* XXX was if (i >= eindex - 1) */ + CQ_RETURN(1); + ADVANCE_CHAR (string, slen, i); + continue; + } + else if (c == '\\') + { + pass_next = 1; + i++; + continue; + } + else if (c == '\'' || c == '"') + { + i = (c == '\'') ? skip_single_quoted (string, slen, ++i) + : skip_double_quoted (string, slen, ++i); + if (i > eindex) + CQ_RETURN(1); + /* no increment, the skip_xxx functions go one past end */ + } + else + ADVANCE_CHAR (string, slen, i); + } + + CQ_RETURN(0); +} + +int +unclosed_pair (string, eindex, openstr) + char *string; + int eindex; + char *openstr; +{ + int i, pass_next, openc, olen; + size_t slen; + DECLARE_MBSTATE; + + slen = strlen (string); + olen = strlen (openstr); + i = pass_next = openc = 0; + while (i <= eindex) + { + if (pass_next) + { + pass_next = 0; + if (i >= eindex) /* XXX was if (i >= eindex - 1) */ + return 0; + ADVANCE_CHAR (string, slen, i); + continue; + } + else if (string[i] == '\\') + { + pass_next = 1; + i++; + continue; + } + else if (STREQN (string + i, openstr, olen)) + { + openc = 1 - openc; + i += olen; + } + else if (string[i] == '\'' || string[i] == '"') + { + i = (string[i] == '\'') ? skip_single_quoted (string, slen, i) + : skip_double_quoted (string, slen, i); + if (i > eindex) + return 0; + } + else + ADVANCE_CHAR (string, slen, i); + } + return (openc); +} + +/* Skip characters in STRING until we find a character in DELIMS, and return + the index of that character. START is the index into string at which we + begin. This is similar in spirit to strpbrk, but it returns an index into + STRING and takes a starting index. This little piece of code knows quite + a lot of shell syntax. It's very similar to skip_double_quoted and other + functions of that ilk. */ +int +skip_to_delim (string, start, delims) + char *string; + int start; + char *delims; +{ + int i, pass_next, backq, si, c; + size_t slen; + char *temp; + DECLARE_MBSTATE; + + slen = strlen (string + start) + start; + no_longjmp_on_fatal_error = 1; + i = start; + pass_next = backq = 0; + while (c = string[i]) + { + if (pass_next) + { + pass_next = 0; + if (c == 0) + CQ_RETURN(i); + ADVANCE_CHAR (string, slen, i); + continue; + } + else if (c == '\\') + { + pass_next = 1; + i++; + continue; + } + else if (backq) + { + if (c == '`') + backq = 0; + ADVANCE_CHAR (string, slen, i); + continue; + } + else if (c == '`') + { + backq = 1; + i++; + continue; + } + else if (c == '\'' || c == '"') + { + i = (c == '\'') ? skip_single_quoted (string, slen, ++i) + : skip_double_quoted (string, slen, ++i); + /* no increment, the skip functions increment past the closing quote. */ + } + else if (c == '$' && (string[i+1] == LPAREN || string[i+1] == LBRACE)) + { + si = i + 2; + if (string[si] == '\0') + CQ_RETURN(si); + + if (string[i+1] == LPAREN) + temp = extract_delimited_string (string, &si, "$(", "(", ")", EX_NOALLOC|EX_COMMAND); /* ) */ + else + temp = extract_dollar_brace_string (string, &si, 0, EX_NOALLOC); + i = si; + if (string[i] == '\0') /* don't increment i past EOS in loop */ + break; + i++; + continue; + } + else if (member (c, delims)) + break; + else + ADVANCE_CHAR (string, slen, i); + } + + CQ_RETURN(i); +} + +/* Split STRING (length SLEN) at DELIMS, and return a WORD_LIST with the + individual words. If DELIMS is NULL, the current value of $IFS is used + to split the string, and the function follows the shell field splitting + rules. SENTINEL is an index to look for. NWP, if non-NULL, + gets the number of words in the returned list. CWP, if non-NULL, gets + the index of the word containing SENTINEL. Non-whitespace chars in + DELIMS delimit separate fields. */ +WORD_LIST * +split_at_delims (string, slen, delims, sentinel, nwp, cwp) + char *string; + int slen; + char *delims; + int sentinel; + int *nwp, *cwp; +{ + int ts, te, i, nw, cw, ifs_split; + char *token, *d, *d2; + WORD_LIST *ret, *tl; + + if (string == 0 || *string == '\0') + { + if (nwp) + *nwp = 0; + if (cwp) + *cwp = 0; + return ((WORD_LIST *)NULL); + } + + d = (delims == 0) ? ifs_value : delims; + ifs_split = delims == 0; + + /* Make d2 the non-whitespace characters in delims */ + d2 = 0; + if (delims) + { + size_t slength; +#if defined (HANDLE_MULTIBYTE) + size_t mblength = 1; +#endif + DECLARE_MBSTATE; + + slength = strlen (delims); + d2 = (char *)xmalloc (slength + 1); + i = ts = 0; + while (delims[i]) + { +#if defined (HANDLE_MULTIBYTE) + mbstate_t state_bak; + state_bak = state; + mblength = MBRLEN (delims + i, slength, &state); + if (MB_INVALIDCH (mblength)) + state = state_bak; + else if (mblength > 1) + { + memcpy (d2 + ts, delims + i, mblength); + ts += mblength; + i += mblength; + slength -= mblength; + continue; + } +#endif + if (whitespace (delims[i]) == 0) + d2[ts++] = delims[i]; + + i++; + slength--; + } + d2[ts] = '\0'; + } + + ret = (WORD_LIST *)NULL; + + /* Remove sequences of whitspace characters at the start of the string, as + long as those characters are delimiters. */ + for (i = 0; member (string[i], d) && spctabnl (string[i]); i++) + ; + if (string[i] == '\0') + return (ret); + + ts = i; + nw = 0; + cw = -1; + while (1) + { + te = skip_to_delim (string, ts, d); + + /* If we have a non-whitespace delimiter character, use it to make a + separate field. This is just about what $IFS splitting does and + is closer to the behavior of the shell parser. */ + if (ts == te && d2 && member (string[ts], d2)) + { + te = ts + 1; + /* If we're using IFS splitting, the non-whitespace delimiter char + and any additional IFS whitespace delimits a field. */ + if (ifs_split) + while (member (string[te], d) && spctabnl (string[te])) + te++; + else + while (member (string[te], d2)) + te++; + } + + token = substring (string, ts, te); + + ret = add_string_to_list (token, ret); + free (token); + nw++; + + if (sentinel >= ts && sentinel <= te) + cw = nw; + + /* If the cursor is at whitespace just before word start, set the + sentinel word to the current word. */ + if (cwp && cw == -1 && sentinel == ts-1) + cw = nw; + + /* If the cursor is at whitespace between two words, make a new, empty + word, add it before (well, after, since the list is in reverse order) + the word we just added, and set the current word to that one. */ + if (cwp && cw == -1 && sentinel < ts) + { + tl = make_word_list (make_word (""), ret->next); + ret->next = tl; + cw = nw; + nw++; + } + + if (string[te] == 0) + break; + + i = te; + while (member (string[i], d) && (ifs_split || spctabnl(string[i]))) + i++; + + if (string[i]) + ts = i; + else + break; + } + + /* Special case for SENTINEL at the end of STRING. If we haven't found + the word containing SENTINEL yet, and the index we're looking for is at + the end of STRING, add an additional null argument and set the current + word pointer to that. */ + if (cwp && cw == -1 && sentinel >= slen) + { + if (whitespace (string[sentinel - 1])) + { + token = ""; + ret = add_string_to_list (token, ret); + nw++; + } + cw = nw; + } + + if (nwp) + *nwp = nw; + if (cwp) + *cwp = cw; + + return (REVERSE_LIST (ret, WORD_LIST *)); +} +#endif /* READLINE */ + +#if 0 +/* UNUSED */ +/* Extract the name of the variable to bind to from the assignment string. */ +char * +assignment_name (string) + char *string; +{ + int offset; + char *temp; + + offset = assignment (string, 0); + if (offset == 0) + return (char *)NULL; + temp = substring (string, 0, offset); + return (temp); +} +#endif + +/* **************************************************************** */ +/* */ +/* Functions to convert strings to WORD_LISTs and vice versa */ +/* */ +/* **************************************************************** */ + +/* Return a single string of all the words in LIST. SEP is the separator + to put between individual elements of LIST in the output string. */ +char * +string_list_internal (list, sep) + WORD_LIST *list; + char *sep; +{ + register WORD_LIST *t; + char *result, *r; + int word_len, sep_len, result_size; + + if (list == 0) + return ((char *)NULL); + + /* Short-circuit quickly if we don't need to separate anything. */ + if (list->next == 0) + return (savestring (list->word->word)); + + /* This is nearly always called with either sep[0] == 0 or sep[1] == 0. */ + sep_len = STRLEN (sep); + result_size = 0; + + for (t = list; t; t = t->next) + { + if (t != list) + result_size += sep_len; + result_size += strlen (t->word->word); + } + + r = result = (char *)xmalloc (result_size + 1); + + for (t = list; t; t = t->next) + { + if (t != list && sep_len) + { + if (sep_len > 1) + { + FASTCOPY (sep, r, sep_len); + r += sep_len; + } + else + *r++ = sep[0]; + } + + word_len = strlen (t->word->word); + FASTCOPY (t->word->word, r, word_len); + r += word_len; + } + + *r = '\0'; + return (result); +} + +/* Return a single string of all the words present in LIST, separating + each word with a space. */ +char * +string_list (list) + WORD_LIST *list; +{ + return (string_list_internal (list, " ")); +} + +/* Return a single string of all the words present in LIST, obeying the + quoting rules for "$*", to wit: (P1003.2, draft 11, 3.5.2) "If the + expansion [of $*] appears within a double quoted string, it expands + to a single field with the value of each parameter separated by the + first character of the IFS variable, or by a if IFS is unset." */ +char * +string_list_dollar_star (list) + WORD_LIST *list; +{ + char *ret; +#if defined (HANDLE_MULTIBYTE) +# if defined (__GNUC__) + char sep[MB_CUR_MAX + 1]; +# else + char *sep = 0; +# endif +#else + char sep[2]; +#endif + +#if defined (HANDLE_MULTIBYTE) +# if !defined (__GNUC__) + sep = (char *)xmalloc (MB_CUR_MAX + 1); +# endif /* !__GNUC__ */ + if (ifs_firstc_len == 1) + { + sep[0] = ifs_firstc[0]; + sep[1] = '\0'; + } + else + { + memcpy (sep, ifs_firstc, ifs_firstc_len); + sep[ifs_firstc_len] = '\0'; + } +#else + sep[0] = ifs_firstc; + sep[1] = '\0'; +#endif + + ret = string_list_internal (list, sep); +#if defined (HANDLE_MULTIBYTE) && !defined (__GNUC__) + free (sep); +#endif + return ret; +} + +/* Turn $@ into a string. If (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) + is non-zero, the $@ appears within double quotes, and we should quote + the list before converting it into a string. If IFS is unset, and the + word is not quoted, we just need to quote CTLESC and CTLNUL characters + in the words in the list, because the default value of $IFS is + , IFS characters in the words in the list should + also be split. If IFS is null, and the word is not quoted, we need + to quote the words in the list to preserve the positional parameters + exactly. */ +char * +string_list_dollar_at (list, quoted) + WORD_LIST *list; + int quoted; +{ + char *ifs, *ret; +#if defined (HANDLE_MULTIBYTE) +# if defined (__GNUC__) + char sep[MB_CUR_MAX + 1]; +# else + char *sep = 0; +# endif /* !__GNUC__ */ +#else + char sep[2]; +#endif + WORD_LIST *tlist; + + /* XXX this could just be ifs = ifs_value; */ + ifs = ifs_var ? value_cell (ifs_var) : (char *)0; + +#if defined (HANDLE_MULTIBYTE) +# if !defined (__GNUC__) + sep = (char *)xmalloc (MB_CUR_MAX + 1); +# endif /* !__GNUC__ */ + if (ifs && *ifs) + { + if (ifs_firstc_len == 1) + { + sep[0] = ifs_firstc[0]; + sep[1] = '\0'; + } + else + { + memcpy (sep, ifs_firstc, ifs_firstc_len); + sep[ifs_firstc_len] = '\0'; + } + } + else + { + sep[0] = ' '; + sep[1] = '\0'; + } +#else + sep[0] = (ifs == 0 || *ifs == 0) ? ' ' : *ifs; + sep[1] = '\0'; +#endif + + tlist = ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) || (ifs && *ifs == 0)) + ? quote_list (list) + : list_quote_escapes (list); + + ret = string_list_internal (tlist, sep); +#if defined (HANDLE_MULTIBYTE) && !defined (__GNUC__) + free (sep); +#endif + return ret; +} + +/* Return the list of words present in STRING. Separate the string into + words at any of the characters found in SEPARATORS. If QUOTED is + non-zero then word in the list will have its quoted flag set, otherwise + the quoted flag is left as make_word () deemed fit. + + This obeys the P1003.2 word splitting semantics. If `separators' is + exactly , then the splitting algorithm is that of + the Bourne shell, which treats any sequence of characters from `separators' + as a delimiter. If IFS is unset, which results in `separators' being set + to "", no splitting occurs. If separators has some other value, the + following rules are applied (`IFS white space' means zero or more + occurrences of , , or , as long as those characters + are in `separators'): + + 1) IFS white space is ignored at the start and the end of the + string. + 2) Each occurrence of a character in `separators' that is not + IFS white space, along with any adjacent occurrences of + IFS white space delimits a field. + 3) Any nonzero-length sequence of IFS white space delimits a field. + */ + +/* BEWARE! list_string strips null arguments. Don't call it twice and + expect to have "" preserved! */ + +/* This performs word splitting and quoted null character removal on + STRING. */ +#define issep(c) \ + (((separators)[0]) ? ((separators)[1] ? isifs(c) \ + : (c) == (separators)[0]) \ + : 0) + +WORD_LIST * +list_string (string, separators, quoted) + register char *string, *separators; + int quoted; +{ + WORD_LIST *result; + WORD_DESC *t; + char *current_word, *s; + int sindex, sh_style_split, whitesep; + size_t slen; + + if (!string || !*string) + return ((WORD_LIST *)NULL); + + sh_style_split = separators && separators[0] == ' ' && + separators[1] == '\t' && + separators[2] == '\n' && + separators[3] == '\0'; + + slen = 0; + /* Remove sequences of whitespace at the beginning of STRING, as + long as those characters appear in IFS. Do not do this if + STRING is quoted or if there are no separator characters. */ + if (!quoted || !separators || !*separators) + { + for (s = string; *s && spctabnl (*s) && issep (*s); s++); + + if (!*s) + return ((WORD_LIST *)NULL); + + string = s; + } + + /* OK, now STRING points to a word that does not begin with white space. + The splitting algorithm is: + extract a word, stopping at a separator + skip sequences of spc, tab, or nl as long as they are separators + This obeys the field splitting rules in Posix.2. */ + slen = (MB_CUR_MAX > 1) ? strlen (string) : 1; + for (result = (WORD_LIST *)NULL, sindex = 0; string[sindex]; ) + { + /* Don't need string length in ADVANCE_CHAR or string_extract_verbatim + unless multibyte chars are possible. */ + current_word = string_extract_verbatim (string, slen, &sindex, separators, 0); + if (current_word == 0) + break; + + /* If we have a quoted empty string, add a quoted null argument. We + want to preserve the quoted null character iff this is a quoted + empty string; otherwise the quoted null characters are removed + below. */ + if (QUOTED_NULL (current_word)) + { + t = alloc_word_desc (); + t->word = make_quoted_char ('\0'); + t->flags |= W_QUOTED|W_HASQUOTEDNULL; + result = make_word_list (t, result); + } + else if (current_word[0] != '\0') + { + /* If we have something, then add it regardless. However, + perform quoted null character removal on the current word. */ + remove_quoted_nulls (current_word); + result = add_string_to_list (current_word, result); + result->word->flags &= ~W_HASQUOTEDNULL; /* just to be sure */ + if (quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT)) + result->word->flags |= W_QUOTED; + } + + /* If we're not doing sequences of separators in the traditional + Bourne shell style, then add a quoted null argument. */ + else if (!sh_style_split && !spctabnl (string[sindex])) + { + t = alloc_word_desc (); + t->word = make_quoted_char ('\0'); + t->flags |= W_QUOTED|W_HASQUOTEDNULL; + result = make_word_list (t, result); + } + + free (current_word); + + /* Note whether or not the separator is IFS whitespace, used later. */ + whitesep = string[sindex] && spctabnl (string[sindex]); + + /* Move past the current separator character. */ + if (string[sindex]) + { + DECLARE_MBSTATE; + ADVANCE_CHAR (string, slen, sindex); + } + + /* Now skip sequences of space, tab, or newline characters if they are + in the list of separators. */ + while (string[sindex] && spctabnl (string[sindex]) && issep (string[sindex])) + sindex++; + + /* If the first separator was IFS whitespace and the current character + is a non-whitespace IFS character, it should be part of the current + field delimiter, not a separate delimiter that would result in an + empty field. Look at POSIX.2, 3.6.5, (3)(b). */ + if (string[sindex] && whitesep && issep (string[sindex]) && !spctabnl (string[sindex])) + { + sindex++; + /* An IFS character that is not IFS white space, along with any + adjacent IFS white space, shall delimit a field. (SUSv3) */ + while (string[sindex] && spctabnl (string[sindex]) && isifs (string[sindex])) + sindex++; + } + } + return (REVERSE_LIST (result, WORD_LIST *)); +} + +/* Parse a single word from STRING, using SEPARATORS to separate fields. + ENDPTR is set to the first character after the word. This is used by + the `read' builtin. This is never called with SEPARATORS != $IFS; + it should be simplified. + + XXX - this function is very similar to list_string; they should be + combined - XXX */ +char * +get_word_from_string (stringp, separators, endptr) + char **stringp, *separators, **endptr; +{ + register char *s; + char *current_word; + int sindex, sh_style_split, whitesep; + size_t slen; + + if (!stringp || !*stringp || !**stringp) + return ((char *)NULL); + + s = *stringp; + + sh_style_split = separators && separators[0] == ' ' && + separators[1] == '\t' && + separators[2] == '\n' && + separators[3] == '\0'; + + slen = 0; + + /* Remove sequences of whitespace at the beginning of STRING, as + long as those characters appear in IFS. */ + if (sh_style_split || !separators || !*separators) + { + for (; *s && spctabnl (*s) && isifs (*s); s++); + + /* If the string is nothing but whitespace, update it and return. */ + if (!*s) + { + *stringp = s; + if (endptr) + *endptr = s; + return ((char *)NULL); + } + } + + /* OK, S points to a word that does not begin with white space. + Now extract a word, stopping at a separator, save a pointer to + the first character after the word, then skip sequences of spc, + tab, or nl as long as they are separators. + + This obeys the field splitting rules in Posix.2. */ + sindex = 0; + /* Don't need string length in ADVANCE_CHAR or string_extract_verbatim + unless multibyte chars are possible. */ + slen = (MB_CUR_MAX > 1) ? strlen (s) : 1; + current_word = string_extract_verbatim (s, slen, &sindex, separators, 0); + + /* Set ENDPTR to the first character after the end of the word. */ + if (endptr) + *endptr = s + sindex; + + /* Note whether or not the separator is IFS whitespace, used later. */ + whitesep = s[sindex] && spctabnl (s[sindex]); + + /* Move past the current separator character. */ + if (s[sindex]) + { + DECLARE_MBSTATE; + ADVANCE_CHAR (s, slen, sindex); + } + + /* Now skip sequences of space, tab, or newline characters if they are + in the list of separators. */ + while (s[sindex] && spctabnl (s[sindex]) && isifs (s[sindex])) + sindex++; + + /* If the first separator was IFS whitespace and the current character is + a non-whitespace IFS character, it should be part of the current field + delimiter, not a separate delimiter that would result in an empty field. + Look at POSIX.2, 3.6.5, (3)(b). */ + if (s[sindex] && whitesep && isifs (s[sindex]) && !spctabnl (s[sindex])) + { + sindex++; + /* An IFS character that is not IFS white space, along with any adjacent + IFS white space, shall delimit a field. */ + while (s[sindex] && spctabnl (s[sindex]) && isifs (s[sindex])) + sindex++; + } + + /* Update STRING to point to the next field. */ + *stringp = s + sindex; + return (current_word); +} + +/* Remove IFS white space at the end of STRING. Start at the end + of the string and walk backwards until the beginning of the string + or we find a character that's not IFS white space and not CTLESC. + Only let CTLESC escape a white space character if SAW_ESCAPE is + non-zero. */ +char * +strip_trailing_ifs_whitespace (string, separators, saw_escape) + char *string, *separators; + int saw_escape; +{ + char *s; + + s = string + STRLEN (string) - 1; + while (s > string && ((spctabnl (*s) && isifs (*s)) || + (saw_escape && *s == CTLESC && spctabnl (s[1])))) + s--; + *++s = '\0'; + return string; +} + +#if 0 +/* UNUSED */ +/* Split STRING into words at whitespace. Obeys shell-style quoting with + backslashes, single and double quotes. */ +WORD_LIST * +list_string_with_quotes (string) + char *string; +{ + WORD_LIST *list; + char *token, *s; + size_t s_len; + int c, i, tokstart, len; + + for (s = string; s && *s && spctabnl (*s); s++) + ; + if (s == 0 || *s == 0) + return ((WORD_LIST *)NULL); + + s_len = strlen (s); + tokstart = i = 0; + list = (WORD_LIST *)NULL; + while (1) + { + c = s[i]; + if (c == '\\') + { + i++; + if (s[i]) + i++; + } + else if (c == '\'') + i = skip_single_quoted (s, s_len, ++i); + else if (c == '"') + i = skip_double_quoted (s, s_len, ++i); + else if (c == 0 || spctabnl (c)) + { + /* We have found the end of a token. Make a word out of it and + add it to the word list. */ + token = substring (s, tokstart, i); + list = add_string_to_list (token, list); + free (token); + while (spctabnl (s[i])) + i++; + if (s[i]) + tokstart = i; + else + break; + } + else + i++; /* normal character */ + } + return (REVERSE_LIST (list, WORD_LIST *)); +} +#endif + +/********************************************************/ +/* */ +/* Functions to perform assignment statements */ +/* */ +/********************************************************/ + +#if defined (ARRAY_VARS) +static SHELL_VAR * +do_compound_assignment (name, value, flags) + char *name, *value; + int flags; +{ + SHELL_VAR *v; + int mklocal; + WORD_LIST *list; + + mklocal = flags & ASS_MKLOCAL; + + if (mklocal && variable_context) + { + list = expand_compound_array_assignment (value, flags); + v = find_variable (name); + if (v == 0 || array_p (v) == 0 || v->context != variable_context) + v = make_local_array_variable (name); + assign_compound_array_list (v, list, flags); + } + else + v = assign_array_from_string (name, value, flags); + + return (v); +} +#endif + +/* Given STRING, an assignment string, get the value of the right side + of the `=', and bind it to the left side. If EXPAND is true, then + perform parameter expansion, command substitution, and arithmetic + expansion on the right-hand side. Perform tilde expansion in any + case. Do not perform word splitting on the result of expansion. */ +static int +do_assignment_internal (word, expand) + const WORD_DESC *word; + int expand; +{ + int offset, tlen, appendop, assign_list, aflags; + char *name, *value; + SHELL_VAR *entry; +#if defined (ARRAY_VARS) + char *t; + int ni; +#endif + const char *string; + + if (word == 0 || word->word == 0) + return 0; + + appendop = assign_list = aflags = 0; + string = word->word; + offset = assignment (string, 0); + name = savestring (string); + value = (char *)NULL; + + if (name[offset] == '=') + { + char *temp; + + if (name[offset - 1] == '+') + { + appendop = 1; + name[offset - 1] = '\0'; + } + + name[offset] = 0; /* might need this set later */ + temp = name + offset + 1; + tlen = STRLEN (temp); + +#if defined (ARRAY_VARS) + if (expand && (word->flags & W_COMPASSIGN)) + { + assign_list = ni = 1; + value = extract_array_assignment_list (temp, &ni); + } + else +#endif + + if (expand && temp[0]) + value = expand_string_if_necessary (temp, 0, expand_string_assignment); + else + value = savestring (temp); + } + + if (value == 0) + { + value = (char *)xmalloc (1); + value[0] = '\0'; + } + + if (echo_command_at_execute) + { + if (appendop) + name[offset - 1] = '+'; + xtrace_print_assignment (name, value, assign_list, 1); + if (appendop) + name[offset - 1] = '\0'; + } + +#define ASSIGN_RETURN(r) do { FREE (value); free (name); return (r); } while (0) + + if (appendop) + aflags |= ASS_APPEND; + +#if defined (ARRAY_VARS) + if (t = xstrchr (name, '[')) /*]*/ + { + if (assign_list) + { + report_error (_("%s: cannot assign list to array member"), name); + ASSIGN_RETURN (0); + } + entry = assign_array_element (name, value, aflags); + if (entry == 0) + ASSIGN_RETURN (0); + } + else if (assign_list) + { + if (word->flags & W_ASSIGNARG) + aflags |= ASS_MKLOCAL; + entry = do_compound_assignment (name, value, aflags); + } + else +#endif /* ARRAY_VARS */ + entry = bind_variable (name, value, aflags); + + stupidly_hack_special_variables (name); + + if (entry) + VUNSETATTR (entry, att_invisible); + + /* Return 1 if the assignment seems to have been performed correctly. */ + ASSIGN_RETURN (entry ? ((readonly_p (entry) == 0) && noassign_p (entry) == 0) : 0); +} + +/* Perform the assignment statement in STRING, and expand the + right side by doing tilde, command and parameter expansion. */ +int +do_assignment (string) + char *string; +{ + WORD_DESC td; + + td.flags = W_ASSIGNMENT; + td.word = string; + + return do_assignment_internal (&td, 1); +} + +int +do_word_assignment (word) + WORD_DESC *word; +{ + return do_assignment_internal (word, 1); +} + +/* Given STRING, an assignment string, get the value of the right side + of the `=', and bind it to the left side. Do not perform any word + expansions on the right hand side. */ +int +do_assignment_no_expand (string) + char *string; +{ + WORD_DESC td; + + td.flags = W_ASSIGNMENT; + td.word = string; + + return (do_assignment_internal (&td, 0)); +} + +/*************************************************** + * * + * Functions to manage the positional parameters * + * * + ***************************************************/ + +/* Return the word list that corresponds to `$*'. */ +WORD_LIST * +list_rest_of_args () +{ + register WORD_LIST *list, *args; + int i; + + /* Break out of the loop as soon as one of the dollar variables is null. */ + for (i = 1, list = (WORD_LIST *)NULL; i < 10 && dollar_vars[i]; i++) + list = make_word_list (make_bare_word (dollar_vars[i]), list); + + for (args = rest_of_args; args; args = args->next) + list = make_word_list (make_bare_word (args->word->word), list); + + return (REVERSE_LIST (list, WORD_LIST *)); +} + +int +number_of_args () +{ + register WORD_LIST *list; + int n; + + for (n = 0; n < 9 && dollar_vars[n+1]; n++) + ; + for (list = rest_of_args; list; list = list->next) + n++; + return n; +} + +/* Return the value of a positional parameter. This handles values > 10. */ +char * +get_dollar_var_value (ind) + intmax_t ind; +{ + char *temp; + WORD_LIST *p; + + if (ind < 10) + temp = dollar_vars[ind] ? savestring (dollar_vars[ind]) : (char *)NULL; + else /* We want something like ${11} */ + { + ind -= 10; + for (p = rest_of_args; p && ind--; p = p->next) + ; + temp = p ? savestring (p->word->word) : (char *)NULL; + } + return (temp); +} + +/* Make a single large string out of the dollar digit variables, + and the rest_of_args. If DOLLAR_STAR is 1, then obey the special + case of "$*" with respect to IFS. */ +char * +string_rest_of_args (dollar_star) + int dollar_star; +{ + register WORD_LIST *list; + char *string; + + list = list_rest_of_args (); + string = dollar_star ? string_list_dollar_star (list) : string_list (list); + dispose_words (list); + return (string); +} + +/* Return a string containing the positional parameters from START to + END, inclusive. If STRING[0] == '*', we obey the rules for $*, + which only makes a difference if QUOTED is non-zero. If QUOTED includes + Q_HERE_DOCUMENT or Q_DOUBLE_QUOTES, this returns a quoted list, otherwise + no quoting chars are added. */ +static char * +pos_params (string, start, end, quoted) + char *string; + int start, end, quoted; +{ + WORD_LIST *save, *params, *h, *t; + char *ret; + int i; + + /* see if we can short-circuit. if start == end, we want 0 parameters. */ + if (start == end) + return ((char *)NULL); + + save = params = list_rest_of_args (); + if (save == 0) + return ((char *)NULL); + + if (start == 0) /* handle ${@:0[:x]} specially */ + { + t = make_word_list (make_word (dollar_vars[0]), params); + save = params = t; + } + + for (i = 1; params && i < start; i++) + params = params->next; + if (params == 0) + return ((char *)NULL); + for (h = t = params; params && i < end; i++) + { + t = params; + params = params->next; + } + + t->next = (WORD_LIST *)NULL; + if (string[0] == '*') + { + if (quoted & Q_DOUBLE_QUOTES) + ret = string_list_dollar_star (quote_list (h)); + else if (quoted & Q_HERE_DOCUMENT) + ret = string_list (quote_list (h)); + else + ret = string_list (h); + } + else + ret = string_list ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) ? quote_list (h) : h); + if (t != params) + t->next = params; + + dispose_words (save); + return (ret); +} + +/******************************************************************/ +/* */ +/* Functions to expand strings to strings or WORD_LISTs */ +/* */ +/******************************************************************/ + +#if defined (PROCESS_SUBSTITUTION) +#define EXP_CHAR(s) (s == '$' || s == '`' || s == '<' || s == '>' || s == CTLESC || s == '~') +#else +#define EXP_CHAR(s) (s == '$' || s == '`' || s == CTLESC || s == '~') +#endif + +/* If there are any characters in STRING that require full expansion, + then call FUNC to expand STRING; otherwise just perform quote + removal if necessary. This returns a new string. */ +static char * +expand_string_if_necessary (string, quoted, func) + char *string; + int quoted; + EXPFUNC *func; +{ + WORD_LIST *list; + size_t slen; + int i, saw_quote; + char *ret; + DECLARE_MBSTATE; + + /* Don't need string length for ADVANCE_CHAR unless multibyte chars possible. */ + slen = (MB_CUR_MAX > 1) ? strlen (string) : 0; + i = saw_quote = 0; + while (string[i]) + { + if (EXP_CHAR (string[i])) + break; + else if (string[i] == '\'' || string[i] == '\\' || string[i] == '"') + saw_quote = 1; + ADVANCE_CHAR (string, slen, i); + } + + if (string[i]) + { + list = (*func) (string, quoted); + if (list) + { + ret = string_list (list); + dispose_words (list); + } + else + ret = (char *)NULL; + } + else if (saw_quote && ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) == 0)) + ret = string_quote_removal (string, quoted); + else + ret = savestring (string); + + return ret; +} + +static inline char * +expand_string_to_string_internal (string, quoted, func) + char *string; + int quoted; + EXPFUNC *func; +{ + WORD_LIST *list; + char *ret; + + if (string == 0 || *string == '\0') + return ((char *)NULL); + + list = (*func) (string, quoted); + if (list) + { + ret = string_list (list); + dispose_words (list); + } + else + ret = (char *)NULL; + + return (ret); +} + +char * +expand_string_to_string (string, quoted) + char *string; + int quoted; +{ + return (expand_string_to_string_internal (string, quoted, expand_string)); +} + +char * +expand_string_unsplit_to_string (string, quoted) + char *string; + int quoted; +{ + return (expand_string_to_string_internal (string, quoted, expand_string_unsplit)); +} + +char * +expand_assignment_string_to_string (string, quoted) + char *string; + int quoted; +{ + return (expand_string_to_string_internal (string, quoted, expand_string_assignment)); +} + +char * +expand_arith_string (string, quoted) + char *string; +{ + return (expand_string_if_necessary (string, quoted, expand_string)); +} + +#if defined (COND_COMMAND) +/* Just remove backslashes in STRING. Returns a new string. */ +char * +remove_backslashes (string) + char *string; +{ + char *r, *ret, *s; + + r = ret = (char *)xmalloc (strlen (string) + 1); + for (s = string; s && *s; ) + { + if (*s == '\\') + s++; + if (*s == 0) + break; + *r++ = *s++; + } + *r = '\0'; + return ret; +} + +/* This needs better error handling. */ +/* Expand W for use as an argument to a unary or binary operator in a + [[...]] expression. If SPECIAL is nonzero, this is the rhs argument + to the != or == operator, and should be treated as a pattern. In + this case, we quote the string specially for the globbing code. The + caller is responsible for removing the backslashes if the unquoted + words is needed later. */ +char * +cond_expand_word (w, special) + WORD_DESC *w; + int special; +{ + char *r, *p; + WORD_LIST *l; + + if (w->word == 0 || w->word[0] == '\0') + return ((char *)NULL); + + l = call_expand_word_internal (w, 0, 0, (int *)0, (int *)0); + if (l) + { + if (special == 0) + { + dequote_list (l); + r = string_list (l); + } + else + { + p = string_list (l); + r = quote_string_for_globbing (p, QGLOB_CVTNULL); + free (p); + } + dispose_words (l); + } + else + r = (char *)NULL; + + return r; +} +#endif + +/* Call expand_word_internal to expand W and handle error returns. + A convenience function for functions that don't want to handle + any errors or free any memory before aborting. */ +static WORD_LIST * +call_expand_word_internal (w, q, i, c, e) + WORD_DESC *w; + int q, i, *c, *e; +{ + WORD_LIST *result; + + result = expand_word_internal (w, q, i, c, e); + if (result == &expand_word_error || result == &expand_word_fatal) + { + /* By convention, each time this error is returned, w->word has + already been freed (it sometimes may not be in the fatal case, + but that doesn't result in a memory leak because we're going + to exit in most cases). */ + w->word = (char *)NULL; + last_command_exit_value = EXECUTION_FAILURE; + exp_jump_to_top_level ((result == &expand_word_error) ? DISCARD : FORCE_EOF); + /* NOTREACHED */ + } + else + return (result); +} + +/* Perform parameter expansion, command substitution, and arithmetic + expansion on STRING, as if it were a word. Leave the result quoted. */ +static WORD_LIST * +expand_string_internal (string, quoted) + char *string; + int quoted; +{ + WORD_DESC td; + WORD_LIST *tresult; + + if (string == 0 || *string == 0) + return ((WORD_LIST *)NULL); + + td.flags = 0; + td.word = savestring (string); + + tresult = call_expand_word_internal (&td, quoted, 0, (int *)NULL, (int *)NULL); + + FREE (td.word); + return (tresult); +} + +/* Expand STRING by performing parameter expansion, command substitution, + and arithmetic expansion. Dequote the resulting WORD_LIST before + returning it, but do not perform word splitting. The call to + remove_quoted_nulls () is in here because word splitting normally + takes care of quote removal. */ +WORD_LIST * +expand_string_unsplit (string, quoted) + char *string; + int quoted; +{ + WORD_LIST *value; + + if (string == 0 || *string == '\0') + return ((WORD_LIST *)NULL); + + expand_no_split_dollar_star = 1; + value = expand_string_internal (string, quoted); + expand_no_split_dollar_star = 0; + + if (value) + { + if (value->word) + { + remove_quoted_nulls (value->word->word); + value->word->flags &= ~W_HASQUOTEDNULL; + } + dequote_list (value); + } + return (value); +} + +/* Expand the rhs of an assignment statement */ +WORD_LIST * +expand_string_assignment (string, quoted) + char *string; + int quoted; +{ + WORD_DESC td; + WORD_LIST *value; + + if (string == 0 || *string == '\0') + return ((WORD_LIST *)NULL); + + expand_no_split_dollar_star = 1; + + td.flags = W_ASSIGNRHS; + td.word = savestring (string); + value = call_expand_word_internal (&td, quoted, 0, (int *)NULL, (int *)NULL); + FREE (td.word); + + expand_no_split_dollar_star = 0; + + if (value) + { + if (value->word) + { + remove_quoted_nulls (value->word->word); + value->word->flags &= ~W_HASQUOTEDNULL; + } + dequote_list (value); + } + return (value); +} + + +/* Expand one of the PS? prompt strings. This is a sort of combination of + expand_string_unsplit and expand_string_internal, but returns the + passed string when an error occurs. Might want to trap other calls + to jump_to_top_level here so we don't endlessly loop. */ +WORD_LIST * +expand_prompt_string (string, quoted) + char *string; + int quoted; +{ + WORD_LIST *value; + WORD_DESC td; + + if (string == 0 || *string == 0) + return ((WORD_LIST *)NULL); + + td.flags = 0; + td.word = savestring (string); + + no_longjmp_on_fatal_error = 1; + value = expand_word_internal (&td, quoted, 0, (int *)NULL, (int *)NULL); + no_longjmp_on_fatal_error = 0; + + if (value == &expand_word_error || value == &expand_word_fatal) + { + value = make_word_list (make_bare_word (string), (WORD_LIST *)NULL); + return value; + } + FREE (td.word); + if (value) + { + if (value->word) + { + remove_quoted_nulls (value->word->word); + value->word->flags &= ~W_HASQUOTEDNULL; + } + dequote_list (value); + } + return (value); +} + +/* Expand STRING just as if you were expanding a word, but do not dequote + the resultant WORD_LIST. This is called only from within this file, + and is used to correctly preserve quoted characters when expanding + things like ${1+"$@"}. This does parameter expansion, command + substitution, arithmetic expansion, and word splitting. */ +static WORD_LIST * +expand_string_leave_quoted (string, quoted) + char *string; + int quoted; +{ + WORD_LIST *tlist; + WORD_LIST *tresult; + + if (string == 0 || *string == '\0') + return ((WORD_LIST *)NULL); + + tlist = expand_string_internal (string, quoted); + + if (tlist) + { + tresult = word_list_split (tlist); + dispose_words (tlist); + return (tresult); + } + return ((WORD_LIST *)NULL); +} + +/* This does not perform word splitting or dequote the WORD_LIST + it returns. */ +static WORD_LIST * +expand_string_for_rhs (string, quoted, dollar_at_p, has_dollar_at) + char *string; + int quoted, *dollar_at_p, *has_dollar_at; +{ + WORD_DESC td; + WORD_LIST *tresult; + + if (string == 0 || *string == '\0') + return (WORD_LIST *)NULL; + + td.flags = 0; + td.word = string; + tresult = call_expand_word_internal (&td, quoted, 1, dollar_at_p, has_dollar_at); + return (tresult); +} + +/* Expand STRING just as if you were expanding a word. This also returns + a list of words. Note that filename globbing is *NOT* done for word + or string expansion, just when the shell is expanding a command. This + does parameter expansion, command substitution, arithmetic expansion, + and word splitting. Dequote the resultant WORD_LIST before returning. */ +WORD_LIST * +expand_string (string, quoted) + char *string; + int quoted; +{ + WORD_LIST *result; + + if (string == 0 || *string == '\0') + return ((WORD_LIST *)NULL); + + result = expand_string_leave_quoted (string, quoted); + return (result ? dequote_list (result) : result); +} + +/*************************************************** + * * + * Functions to handle quoting chars * + * * + ***************************************************/ + +/* Conventions: + + A string with s[0] == CTLNUL && s[1] == 0 is a quoted null string. + The parser passes CTLNUL as CTLESC CTLNUL. */ + +/* Quote escape characters in string s, but no other characters. This is + used to protect CTLESC and CTLNUL in variable values from the rest of + the word expansion process after the variable is expanded. */ +char * +quote_escapes (string) + char *string; +{ + register char *s, *t; + size_t slen; + char *result, *send; + DECLARE_MBSTATE; + + slen = strlen (string); + send = string + slen; + + t = result = (char *)xmalloc ((slen * 2) + 1); + s = string; + + while (*s) + { + if (*s == CTLESC || *s == CTLNUL) + *t++ = CTLESC; + COPY_CHAR_P (t, s, send); + } + *t = '\0'; + return (result); +} + +static WORD_LIST * +list_quote_escapes (list) + WORD_LIST *list; +{ + register WORD_LIST *w; + char *t; + + for (w = list; w; w = w->next) + { + t = w->word->word; + w->word->word = quote_escapes (t); + free (t); + } + return list; +} + +/* Inverse of quote_escapes; remove CTLESC protecting CTLESC or CTLNUL. + + The parser passes us CTLESC as CTLESC CTLESC and CTLNUL as CTLESC CTLNUL. + This is necessary to make unquoted CTLESC and CTLNUL characters in the + data stream pass through properly. + + We need to remove doubled CTLESC characters inside quoted strings before + quoting the entire string, so we do not double the number of CTLESC + characters. + + Also used by parts of the pattern substitution code. */ +static char * +dequote_escapes (string) + char *string; +{ + register char *s, *t; + size_t slen; + char *result, *send; + DECLARE_MBSTATE; + + if (string == 0) + return string; + + slen = strlen (string); + send = string + slen; + + t = result = (char *)xmalloc (slen + 1); + s = string; + + if (strchr (string, CTLESC) == 0) + return (strcpy (result, s)); + + while (*s) + { + if (*s == CTLESC && (s[1] == CTLESC || s[1] == CTLNUL)) + { + s++; + if (*s == '\0') + break; + } + COPY_CHAR_P (t, s, send); + } + *t = '\0'; + return result; +} + +/* Return a new string with the quoted representation of character C. + This turns "" into QUOTED_NULL, so the W_HASQUOTEDNULL flag needs to be + set in any resultant WORD_DESC where this value is the word. */ +static char * +make_quoted_char (c) + int c; +{ + char *temp; + + temp = (char *)xmalloc (3); + if (c == 0) + { + temp[0] = CTLNUL; + temp[1] = '\0'; + } + else + { + temp[0] = CTLESC; + temp[1] = c; + temp[2] = '\0'; + } + return (temp); +} + +/* Quote STRING, returning a new string. This turns "" into QUOTED_NULL, so + the W_HASQUOTEDNULL flag needs to be set in any resultant WORD_DESC where + this value is the word. */ +char * +quote_string (string) + char *string; +{ + register char *t; + size_t slen; + char *result, *send; + + if (*string == 0) + { + result = (char *)xmalloc (2); + result[0] = CTLNUL; + result[1] = '\0'; + } + else + { + DECLARE_MBSTATE; + + slen = strlen (string); + send = string + slen; + + result = (char *)xmalloc ((slen * 2) + 1); + + for (t = result; string < send; ) + { + *t++ = CTLESC; + COPY_CHAR_P (t, string, send); + } + *t = '\0'; + } + return (result); +} + +/* De-quote quoted characters in STRING. */ +char * +dequote_string (string) + char *string; +{ + register char *s, *t; + size_t slen; + char *result, *send; + DECLARE_MBSTATE; + + slen = strlen (string); + + t = result = (char *)xmalloc (slen + 1); + + if (QUOTED_NULL (string)) + { + result[0] = '\0'; + return (result); + } + + /* If no character in the string can be quoted, don't bother examining + each character. Just return a copy of the string passed to us. */ + if (strchr (string, CTLESC) == NULL) + return (strcpy (result, string)); + + send = string + slen; + s = string; + while (*s) + { + if (*s == CTLESC) + { + s++; + if (*s == '\0') + break; + } + COPY_CHAR_P (t, s, send); + } + + *t = '\0'; + return (result); +} + +/* Quote the entire WORD_LIST list. */ +static WORD_LIST * +quote_list (list) + WORD_LIST *list; +{ + register WORD_LIST *w; + char *t; + + for (w = list; w; w = w->next) + { + t = w->word->word; + w->word->word = quote_string (t); + free (t); + w->word->flags |= W_QUOTED; + /* XXX - turn on W_HAVEQUOTEDNULL here? */ + } + return list; +} + +/* De-quote quoted characters in each word in LIST. */ +WORD_LIST * +dequote_list (list) + WORD_LIST *list; +{ + register char *s; + register WORD_LIST *tlist; + + for (tlist = list; tlist; tlist = tlist->next) + { + s = dequote_string (tlist->word->word); + free (tlist->word->word); + tlist->word->word = s; + /* XXX - turn off W_HAVEQUOTEDNULL here? */ + } + return list; +} + +/* Remove CTLESC protecting a CTLESC or CTLNUL in place. Return the passed + string. */ +static char * +remove_quoted_escapes (string) + char *string; +{ + char *t; + + if (string) + { + t = dequote_escapes (string); + strcpy (string, t); + free (t); + } + + return (string); +} + +/* Perform quoted null character removal on STRING. We don't allow any + quoted null characters in the middle or at the ends of strings because + of how expand_word_internal works. remove_quoted_nulls () turns + STRING into an empty string iff it only consists of a quoted null, + and removes all unquoted CTLNUL characters. */ +static char * +remove_quoted_nulls (string) + char *string; +{ + register size_t slen; + register int i, j, prev_i; + DECLARE_MBSTATE; + + if (strchr (string, CTLNUL) == 0) /* XXX */ + return string; /* XXX */ + + slen = strlen (string); + i = j = 0; + + while (i < slen) + { + if (string[i] == CTLESC) + { + /* Old code had j++, but we cannot assume that i == j at this + point -- what if a CTLNUL has already been removed from the + string? We don't want to drop the CTLESC or recopy characters + that we've already copied down. */ + i++; string[j++] = CTLESC; + if (i == slen) + break; + } + else if (string[i] == CTLNUL) + i++; + + prev_i = i; + ADVANCE_CHAR (string, slen, i); + if (j < prev_i) + { + do string[j++] = string[prev_i++]; while (prev_i < i); + } + else + j = i; + } + string[j] = '\0'; + + return (string); +} + +/* Perform quoted null character removal on each element of LIST. + This modifies LIST. */ +void +word_list_remove_quoted_nulls (list) + WORD_LIST *list; +{ + register WORD_LIST *t; + + for (t = list; t; t = t->next) + { + remove_quoted_nulls (t->word->word); + t->word->flags &= ~W_HASQUOTEDNULL; + } +} + +/* **************************************************************** */ +/* */ +/* Functions for Matching and Removing Patterns */ +/* */ +/* **************************************************************** */ + +#if defined (HANDLE_MULTIBYTE) +#if 0 /* Currently unused */ +static unsigned char * +mb_getcharlens (string, len) + char *string; + int len; +{ + int i, offset, last; + unsigned char *ret; + char *p; + DECLARE_MBSTATE; + + i = offset = 0; + last = 0; + ret = (unsigned char *)xmalloc (len); + memset (ret, 0, len); + while (string[last]) + { + ADVANCE_CHAR (string, len, offset); + ret[last] = offset - last; + last = offset; + } + return ret; +} +#endif +#endif + +/* Remove the portion of PARAM matched by PATTERN according to OP, where OP + can have one of 4 values: + RP_LONG_LEFT remove longest matching portion at start of PARAM + RP_SHORT_LEFT remove shortest matching portion at start of PARAM + RP_LONG_RIGHT remove longest matching portion at end of PARAM + RP_SHORT_RIGHT remove shortest matching portion at end of PARAM +*/ + +#define RP_LONG_LEFT 1 +#define RP_SHORT_LEFT 2 +#define RP_LONG_RIGHT 3 +#define RP_SHORT_RIGHT 4 + +static char * +remove_upattern (param, pattern, op) + char *param, *pattern; + int op; +{ + register int len; + register char *end; + register char *p, *ret, c; + + len = STRLEN (param); + end = param + len; + + switch (op) + { + case RP_LONG_LEFT: /* remove longest match at start */ + for (p = end; p >= param; p--) + { + c = *p; *p = '\0'; + if (strmatch (pattern, param, FNMATCH_EXTFLAG) != FNM_NOMATCH) + { + *p = c; + return (savestring (p)); + } + *p = c; + + } + break; + + case RP_SHORT_LEFT: /* remove shortest match at start */ + for (p = param; p <= end; p++) + { + c = *p; *p = '\0'; + if (strmatch (pattern, param, FNMATCH_EXTFLAG) != FNM_NOMATCH) + { + *p = c; + return (savestring (p)); + } + *p = c; + } + break; + + case RP_LONG_RIGHT: /* remove longest match at end */ + for (p = param; p <= end; p++) + { + if (strmatch (pattern, p, FNMATCH_EXTFLAG) != FNM_NOMATCH) + { + c = *p; *p = '\0'; + ret = savestring (param); + *p = c; + return (ret); + } + } + break; + + case RP_SHORT_RIGHT: /* remove shortest match at end */ + for (p = end; p >= param; p--) + { + if (strmatch (pattern, p, FNMATCH_EXTFLAG) != FNM_NOMATCH) + { + c = *p; *p = '\0'; + ret = savestring (param); + *p = c; + return (ret); + } + } + break; + } + + return (savestring (param)); /* no match, return original string */ +} + +#if defined (HANDLE_MULTIBYTE) +static wchar_t * +remove_wpattern (wparam, wstrlen, wpattern, op) + wchar_t *wparam; + size_t wstrlen; + wchar_t *wpattern; + int op; +{ + wchar_t wc, *ret; + int n; + + switch (op) + { + case RP_LONG_LEFT: /* remove longest match at start */ + for (n = wstrlen; n >= 0; n--) + { + wc = wparam[n]; wparam[n] = L'\0'; + if (wcsmatch (wpattern, wparam, FNMATCH_EXTFLAG) != FNM_NOMATCH) + { + wparam[n] = wc; + return (wcsdup (wparam + n)); + } + wparam[n] = wc; + } + break; + + case RP_SHORT_LEFT: /* remove shortest match at start */ + for (n = 0; n <= wstrlen; n++) + { + wc = wparam[n]; wparam[n] = L'\0'; + if (wcsmatch (wpattern, wparam, FNMATCH_EXTFLAG) != FNM_NOMATCH) + { + wparam[n] = wc; + return (wcsdup (wparam + n)); + } + wparam[n] = wc; + } + break; + + case RP_LONG_RIGHT: /* remove longest match at end */ + for (n = 0; n <= wstrlen; n++) + { + if (wcsmatch (wpattern, wparam + n, FNMATCH_EXTFLAG) != FNM_NOMATCH) + { + wc = wparam[n]; wparam[n] = L'\0'; + ret = wcsdup (wparam); + wparam[n] = wc; + return (ret); + } + } + break; + + case RP_SHORT_RIGHT: /* remove shortest match at end */ + for (n = wstrlen; n >= 0; n--) + { + if (wcsmatch (wpattern, wparam + n, FNMATCH_EXTFLAG) != FNM_NOMATCH) + { + wc = wparam[n]; wparam[n] = L'\0'; + ret = wcsdup (wparam); + wparam[n] = wc; + return (ret); + } + } + break; + } + + return (wcsdup (wparam)); /* no match, return original string */ +} +#endif /* HANDLE_MULTIBYTE */ + +static char * +remove_pattern (param, pattern, op) + char *param, *pattern; + int op; +{ + if (param == NULL) + return (param); + if (*param == '\0' || pattern == NULL || *pattern == '\0') /* minor optimization */ + return (savestring (param)); + +#if defined (HANDLE_MULTIBYTE) + if (MB_CUR_MAX > 1) + { + wchar_t *ret, *oret; + size_t n; + wchar_t *wparam, *wpattern; + mbstate_t ps; + char *xret; + + n = xdupmbstowcs (&wpattern, NULL, pattern); + if (n == (size_t)-1) + return (remove_upattern (param, pattern, op)); + n = xdupmbstowcs (&wparam, NULL, param); + if (n == (size_t)-1) + { + free (wpattern); + return (remove_upattern (param, pattern, op)); + } + oret = ret = remove_wpattern (wparam, n, wpattern, op); + + free (wparam); + free (wpattern); + + n = strlen (param); + xret = (char *)xmalloc (n + 1); + memset (&ps, '\0', sizeof (mbstate_t)); + n = wcsrtombs (xret, (const wchar_t **)&ret, n, &ps); + xret[n] = '\0'; /* just to make sure */ + free (oret); + return xret; + } + else +#endif + return (remove_upattern (param, pattern, op)); +} + +/* Return 1 of the first character of STRING could match the first + character of pattern PAT. Used to avoid n2 calls to strmatch(). */ +static int +match_pattern_char (pat, string) + char *pat, *string; +{ + char c; + + if (*string == 0) + return (0); + + switch (c = *pat++) + { + default: + return (*string == c); + case '\\': + return (*string == *pat); + case '?': + return (*pat == LPAREN ? 1 : (*string != '\0')); + case '*': + return (1); + case '+': + case '!': + case '@': + return (*pat == LPAREN ? 1 : (*string == c)); + case '[': + return (*string != '\0'); + } +} + +/* Match PAT anywhere in STRING and return the match boundaries. + This returns 1 in case of a successful match, 0 otherwise. SP + and EP are pointers into the string where the match begins and + ends, respectively. MTYPE controls what kind of match is attempted. + MATCH_BEG and MATCH_END anchor the match at the beginning and end + of the string, respectively. The longest match is returned. */ +static int +match_upattern (string, pat, mtype, sp, ep) + char *string, *pat; + int mtype; + char **sp, **ep; +{ + int c, len; + register char *p, *p1, *npat; + char *end; + + /* If the pattern doesn't match anywhere in the string, go ahead and + short-circuit right away. A minor optimization, saves a bunch of + unnecessary calls to strmatch (up to N calls for a string of N + characters) if the match is unsuccessful. To preserve the semantics + of the substring matches below, we make sure that the pattern has + `*' as first and last character, making a new pattern if necessary. */ + /* XXX - check this later if I ever implement `**' with special meaning, + since this will potentially result in `**' at the beginning or end */ + len = STRLEN (pat); + if (pat[0] != '*' || pat[len - 1] != '*') + { + p = npat = (char *)xmalloc (len + 3); + p1 = pat; + if (*p1 != '*') + *p++ = '*'; + while (*p1) + *p++ = *p1++; + if (p1[-1] != '*' || p[-2] == '\\') + *p++ = '*'; + *p = '\0'; + } + else + npat = pat; + c = strmatch (npat, string, FNMATCH_EXTFLAG); + if (npat != pat) + free (npat); + if (c == FNM_NOMATCH) + return (0); + + len = STRLEN (string); + end = string + len; + + switch (mtype) + { + case MATCH_ANY: + for (p = string; p <= end; p++) + { + if (match_pattern_char (pat, p)) + { + for (p1 = end; p1 >= p; p1--) + { + c = *p1; *p1 = '\0'; + if (strmatch (pat, p, FNMATCH_EXTFLAG) == 0) + { + *p1 = c; + *sp = p; + *ep = p1; + return 1; + } + *p1 = c; + } + } + } + + return (0); + + case MATCH_BEG: + if (match_pattern_char (pat, string) == 0) + return (0); + + for (p = end; p >= string; p--) + { + c = *p; *p = '\0'; + if (strmatch (pat, string, FNMATCH_EXTFLAG) == 0) + { + *p = c; + *sp = string; + *ep = p; + return 1; + } + *p = c; + } + + return (0); + + case MATCH_END: + for (p = string; p <= end; p++) + { + if (strmatch (pat, p, FNMATCH_EXTFLAG) == 0) + { + *sp = p; + *ep = end; + return 1; + } + + } + + return (0); + } + + return (0); +} + +#if defined (HANDLE_MULTIBYTE) +/* Return 1 of the first character of WSTRING could match the first + character of pattern WPAT. Wide character version. */ +static int +match_pattern_wchar (wpat, wstring) + wchar_t *wpat, *wstring; +{ + wchar_t wc; + + if (*wstring == 0) + return (0); + + switch (wc = *wpat++) + { + default: + return (*wstring == wc); + case L'\\': + return (*wstring == *wpat); + case L'?': + return (*wpat == LPAREN ? 1 : (*wstring != L'\0')); + case L'*': + return (1); + case L'+': + case L'!': + case L'@': + return (*wpat == LPAREN ? 1 : (*wstring == wc)); + case L'[': + return (*wstring != L'\0'); + } +} + +/* Match WPAT anywhere in WSTRING and return the match boundaries. + This returns 1 in case of a successful match, 0 otherwise. Wide + character version. */ +static int +match_wpattern (wstring, indices, wstrlen, wpat, mtype, sp, ep) + wchar_t *wstring; + char **indices; + size_t wstrlen; + wchar_t *wpat; + int mtype; + char **sp, **ep; +{ + wchar_t wc, *wp, *nwpat, *wp1; + int len; +#if 0 + size_t n, n1; /* Apple's gcc seems to miscompile this badly */ +#else + int n, n1; +#endif + + /* If the pattern doesn't match anywhere in the string, go ahead and + short-circuit right away. A minor optimization, saves a bunch of + unnecessary calls to strmatch (up to N calls for a string of N + characters) if the match is unsuccessful. To preserve the semantics + of the substring matches below, we make sure that the pattern has + `*' as first and last character, making a new pattern if necessary. */ + /* XXX - check this later if I ever implement `**' with special meaning, + since this will potentially result in `**' at the beginning or end */ + len = wcslen (wpat); + if (wpat[0] != L'*' || wpat[len - 1] != L'*') + { + wp = nwpat = (wchar_t *)xmalloc ((len + 3) * sizeof (wchar_t)); + wp1 = wpat; + if (*wp1 != L'*') + *wp++ = L'*'; + while (*wp1 != L'\0') + *wp++ = *wp1++; + if (wp1[-1] != L'*' || wp1[-2] == L'\\') + *wp++ = L'*'; + *wp = '\0'; + } + else + nwpat = wpat; + len = wcsmatch (nwpat, wstring, FNMATCH_EXTFLAG); + if (nwpat != wpat) + free (nwpat); + if (len == FNM_NOMATCH) + return (0); + + switch (mtype) + { + case MATCH_ANY: + for (n = 0; n <= wstrlen; n++) + { + if (match_pattern_wchar (wpat, wstring + n)) + { + for (n1 = wstrlen; n1 >= n; n1--) + { + wc = wstring[n1]; wstring[n1] = L'\0'; + if (wcsmatch (wpat, wstring + n, FNMATCH_EXTFLAG) == 0) + { + wstring[n1] = wc; + *sp = indices[n]; + *ep = indices[n1]; + return 1; + } + wstring[n1] = wc; + } + } + } + + return (0); + + case MATCH_BEG: + if (match_pattern_wchar (wpat, wstring) == 0) + return (0); + + for (n = wstrlen; n >= 0; n--) + { + wc = wstring[n]; wstring[n] = L'\0'; + if (wcsmatch (wpat, wstring, FNMATCH_EXTFLAG) == 0) + { + wstring[n] = wc; + *sp = indices[0]; + *ep = indices[n]; + return 1; + } + wstring[n] = wc; + } + + return (0); + + case MATCH_END: + for (n = 0; n <= wstrlen; n++) + { + if (wcsmatch (wpat, wstring + n, FNMATCH_EXTFLAG) == 0) + { + *sp = indices[n]; + *ep = indices[wstrlen]; + return 1; + } + } + + return (0); + } + + return (0); +} +#endif /* HANDLE_MULTIBYTE */ + +static int +match_pattern (string, pat, mtype, sp, ep) + char *string, *pat; + int mtype; + char **sp, **ep; +{ +#if defined (HANDLE_MULTIBYTE) + int ret; + size_t n; + wchar_t *wstring, *wpat; + char **indices; +#endif + + if (string == 0 || *string == 0 || pat == 0 || *pat == 0) + return (0); + +#if defined (HANDLE_MULTIBYTE) + if (MB_CUR_MAX > 1) + { + n = xdupmbstowcs (&wpat, NULL, pat); + if (n == (size_t)-1) + return (match_upattern (string, pat, mtype, sp, ep)); + n = xdupmbstowcs (&wstring, &indices, string); + if (n == (size_t)-1) + { + free (wpat); + return (match_upattern (string, pat, mtype, sp, ep)); + } + ret = match_wpattern (wstring, indices, n, wpat, mtype, sp, ep); + + free (wpat); + free (wstring); + free (indices); + + return (ret); + } + else +#endif + return (match_upattern (string, pat, mtype, sp, ep)); +} + +static int +getpatspec (c, value) + int c; + char *value; +{ + if (c == '#') + return ((*value == '#') ? RP_LONG_LEFT : RP_SHORT_LEFT); + else /* c == '%' */ + return ((*value == '%') ? RP_LONG_RIGHT : RP_SHORT_RIGHT); +} + +/* Posix.2 says that the WORD should be run through tilde expansion, + parameter expansion, command substitution and arithmetic expansion. + This leaves the result quoted, so quote_string_for_globbing () has + to be called to fix it up for strmatch (). If QUOTED is non-zero, + it means that the entire expression was enclosed in double quotes. + This means that quoting characters in the pattern do not make any + special pattern characters quoted. For example, the `*' in the + following retains its special meaning: "${foo#'*'}". */ +static char * +getpattern (value, quoted, expandpat) + char *value; + int quoted, expandpat; +{ + char *pat, *tword; + WORD_LIST *l; +#if 0 + int i; +#endif + + /* There is a problem here: how to handle single or double quotes in the + pattern string when the whole expression is between double quotes? + POSIX.2 says that enclosing double quotes do not cause the pattern to + be quoted, but does that leave us a problem with @ and array[@] and their + expansions inside a pattern? */ +#if 0 + if (expandpat && (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) && *tword) + { + i = 0; + pat = string_extract_double_quoted (tword, &i, 1); + free (tword); + tword = pat; + } +#endif + + /* expand_string_for_rhs () leaves WORD quoted and does not perform + word splitting. */ + l = *value ? expand_string_for_rhs (value, + (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) ? Q_PATQUOTE : quoted, + (int *)NULL, (int *)NULL) + : (WORD_LIST *)0; + pat = string_list (l); + dispose_words (l); + if (pat) + { + tword = quote_string_for_globbing (pat, QGLOB_CVTNULL); + free (pat); + pat = tword; + } + return (pat); +} + +#if 0 +/* Handle removing a pattern from a string as a result of ${name%[%]value} + or ${name#[#]value}. */ +static char * +variable_remove_pattern (value, pattern, patspec, quoted) + char *value, *pattern; + int patspec, quoted; +{ + char *tword; + + tword = remove_pattern (value, pattern, patspec); + + return (tword); +} +#endif + +static char * +list_remove_pattern (list, pattern, patspec, itype, quoted) + WORD_LIST *list; + char *pattern; + int patspec, itype, quoted; +{ + WORD_LIST *new, *l; + WORD_DESC *w; + char *tword; + + for (new = (WORD_LIST *)NULL, l = list; l; l = l->next) + { + tword = remove_pattern (l->word->word, pattern, patspec); + w = alloc_word_desc (); + w->word = tword ? tword : savestring (""); + new = make_word_list (w, new); + } + + l = REVERSE_LIST (new, WORD_LIST *); + if (itype == '*') + tword = (quoted & Q_DOUBLE_QUOTES) ? string_list_dollar_star (l) : string_list (l); + else + tword = string_list ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) ? quote_list (l) : l); + + dispose_words (l); + return (tword); +} + +static char * +parameter_list_remove_pattern (itype, pattern, patspec, quoted) + int itype; + char *pattern; + int patspec, quoted; +{ + char *ret; + WORD_LIST *list; + + list = list_rest_of_args (); + if (list == 0) + return ((char *)NULL); + ret = list_remove_pattern (list, pattern, patspec, itype, quoted); + dispose_words (list); + return (ret); +} + +#if defined (ARRAY_VARS) +static char * +array_remove_pattern (a, pattern, patspec, varname, quoted) + ARRAY *a; + char *pattern; + int patspec; + char *varname; /* so we can figure out how it's indexed */ + int quoted; +{ + int itype; + char *ret; + WORD_LIST *list; + SHELL_VAR *v; + + /* compute itype from varname here */ + v = array_variable_part (varname, &ret, 0); + itype = ret[0]; + + list = array_to_word_list (a); + if (list == 0) + return ((char *)NULL); + ret = list_remove_pattern (list, pattern, patspec, itype, quoted); + dispose_words (list); + + return ret; +} +#endif /* ARRAY_VARS */ + +static char * +parameter_brace_remove_pattern (varname, value, patstr, rtype, quoted) + char *varname, *value, *patstr; + int rtype, quoted; +{ + int vtype, patspec, starsub; + char *temp1, *val, *pattern; + SHELL_VAR *v; + + if (value == 0) + return ((char *)NULL); + + this_command_name = varname; + + vtype = get_var_and_type (varname, value, quoted, &v, &val); + if (vtype == -1) + return ((char *)NULL); + + starsub = vtype & VT_STARSUB; + vtype &= ~VT_STARSUB; + + patspec = getpatspec (rtype, patstr); + if (patspec == RP_LONG_LEFT || patspec == RP_LONG_RIGHT) + patstr++; + + pattern = getpattern (patstr, quoted, 1); + + temp1 = (char *)NULL; /* shut up gcc */ + switch (vtype) + { + case VT_VARIABLE: + case VT_ARRAYMEMBER: + temp1 = remove_pattern (val, pattern, patspec); + if (vtype == VT_VARIABLE) + FREE (val); + if (temp1) + { + val = quote_escapes (temp1); + free (temp1); + temp1 = val; + } + break; +#if defined (ARRAY_VARS) + case VT_ARRAYVAR: + temp1 = array_remove_pattern (array_cell (v), pattern, patspec, varname, quoted); + if (temp1 && ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) == 0)) + { + val = quote_escapes (temp1); + free (temp1); + temp1 = val; + } + break; +#endif + case VT_POSPARMS: + temp1 = parameter_list_remove_pattern (varname[0], pattern, patspec, quoted); + if (temp1 && ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) == 0)) + { + val = quote_escapes (temp1); + free (temp1); + temp1 = val; + } + break; + } + + FREE (pattern); + return temp1; +} + +/******************************************* + * * + * Functions to expand WORD_DESCs * + * * + *******************************************/ + +/* Expand WORD, performing word splitting on the result. This does + parameter expansion, command substitution, arithmetic expansion, + word splitting, and quote removal. */ + +WORD_LIST * +expand_word (word, quoted) + WORD_DESC *word; + int quoted; +{ + WORD_LIST *result, *tresult; + + tresult = call_expand_word_internal (word, quoted, 0, (int *)NULL, (int *)NULL); + result = word_list_split (tresult); + dispose_words (tresult); + return (result ? dequote_list (result) : result); +} + +/* Expand WORD, but do not perform word splitting on the result. This + does parameter expansion, command substitution, arithmetic expansion, + and quote removal. */ +WORD_LIST * +expand_word_unsplit (word, quoted) + WORD_DESC *word; + int quoted; +{ + WORD_LIST *result; + + expand_no_split_dollar_star = 1; + result = call_expand_word_internal (word, quoted, 0, (int *)NULL, (int *)NULL); + expand_no_split_dollar_star = 0; + + return (result ? dequote_list (result) : result); +} + +/* Perform shell expansions on WORD, but do not perform word splitting or + quote removal on the result. */ +WORD_LIST * +expand_word_leave_quoted (word, quoted) + WORD_DESC *word; + int quoted; +{ + return (call_expand_word_internal (word, quoted, 0, (int *)NULL, (int *)NULL)); +} + +#if defined (PROCESS_SUBSTITUTION) + +/*****************************************************************/ +/* */ +/* Hacking Process Substitution */ +/* */ +/*****************************************************************/ + +#if !defined (HAVE_DEV_FD) +/* Named pipes must be removed explicitly with `unlink'. This keeps a list + of FIFOs the shell has open. unlink_fifo_list will walk the list and + unlink all of them. add_fifo_list adds the name of an open FIFO to the + list. NFIFO is a count of the number of FIFOs in the list. */ +#define FIFO_INCR 20 + +struct temp_fifo { + char *file; + pid_t proc; +}; + +static struct temp_fifo *fifo_list = (struct temp_fifo *)NULL; +static int nfifo; +static int fifo_list_size; + +static void +add_fifo_list (pathname) + char *pathname; +{ + if (nfifo >= fifo_list_size - 1) + { + fifo_list_size += FIFO_INCR; + fifo_list = (struct temp_fifo *)xrealloc (fifo_list, + fifo_list_size * sizeof (struct temp_fifo)); + } + + fifo_list[nfifo].file = savestring (pathname); + nfifo++; +} + +void +unlink_fifo_list () +{ + int saved, i, j; + + if (nfifo == 0) + return; + + for (i = saved = 0; i < nfifo; i++) + { + if ((fifo_list[i].proc == -1) || (kill(fifo_list[i].proc, 0) == -1)) + { + unlink (fifo_list[i].file); + free (fifo_list[i].file); + fifo_list[i].file = (char *)NULL; + fifo_list[i].proc = -1; + } + else + saved++; + } + + /* If we didn't remove some of the FIFOs, compact the list. */ + if (saved) + { + for (i = j = 0; i < nfifo; i++) + if (fifo_list[i].file) + { + fifo_list[j].file = fifo_list[i].file; + fifo_list[j].proc = fifo_list[i].proc; + j++; + } + nfifo = j; + } + else + nfifo = 0; +} + +int +fifos_pending () +{ + return nfifo; +} + +static char * +make_named_pipe () +{ + char *tname; + + tname = sh_mktmpname ("sh-np", MT_USERANDOM|MT_USETMPDIR); + if (mkfifo (tname, 0600) < 0) + { + free (tname); + return ((char *)NULL); + } + + add_fifo_list (tname); + return (tname); +} + +#else /* HAVE_DEV_FD */ + +/* DEV_FD_LIST is a bitmap of file descriptors attached to pipes the shell + has open to children. NFDS is a count of the number of bits currently + set in DEV_FD_LIST. TOTFDS is a count of the highest possible number + of open files. */ +static char *dev_fd_list = (char *)NULL; +static int nfds; +static int totfds; /* The highest possible number of open files. */ + +static void +add_fifo_list (fd) + int fd; +{ + if (!dev_fd_list || fd >= totfds) + { + int ofds; + + ofds = totfds; + totfds = getdtablesize (); + if (totfds < 0 || totfds > 256) + totfds = 256; + if (fd > totfds) + totfds = fd + 2; + + dev_fd_list = (char *)xrealloc (dev_fd_list, totfds); + memset (dev_fd_list + ofds, '\0', totfds - ofds); + } + + dev_fd_list[fd] = 1; + nfds++; +} + +int +fifos_pending () +{ + return 0; /* used for cleanup; not needed with /dev/fd */ +} + +void +unlink_fifo_list () +{ + register int i; + + if (nfds == 0) + return; + + for (i = 0; nfds && i < totfds; i++) + if (dev_fd_list[i]) + { + close (i); + dev_fd_list[i] = 0; + nfds--; + } + + nfds = 0; +} + +#if defined (NOTDEF) +print_dev_fd_list () +{ + register int i; + + fprintf (stderr, "pid %ld: dev_fd_list:", (long)getpid ()); + fflush (stderr); + + for (i = 0; i < totfds; i++) + { + if (dev_fd_list[i]) + fprintf (stderr, " %d", i); + } + fprintf (stderr, "\n"); +} +#endif /* NOTDEF */ + +static char * +make_dev_fd_filename (fd) + int fd; +{ + char *ret, intbuf[INT_STRLEN_BOUND (int) + 1], *p; + + ret = (char *)xmalloc (sizeof (DEV_FD_PREFIX) + 4); + + strcpy (ret, DEV_FD_PREFIX); + p = inttostr (fd, intbuf, sizeof (intbuf)); + strcpy (ret + sizeof (DEV_FD_PREFIX) - 1, p); + + add_fifo_list (fd); + return (ret); +} + +#endif /* HAVE_DEV_FD */ + +/* Return a filename that will open a connection to the process defined by + executing STRING. HAVE_DEV_FD, if defined, means open a pipe and return + a filename in /dev/fd corresponding to a descriptor that is one of the + ends of the pipe. If not defined, we use named pipes on systems that have + them. Systems without /dev/fd and named pipes are out of luck. + + OPEN_FOR_READ_IN_CHILD, if 1, means open the named pipe for reading or + use the read end of the pipe and dup that file descriptor to fd 0 in + the child. If OPEN_FOR_READ_IN_CHILD is 0, we open the named pipe for + writing or use the write end of the pipe in the child, and dup that + file descriptor to fd 1 in the child. The parent does the opposite. */ + +static char * +process_substitute (string, open_for_read_in_child) + char *string; + int open_for_read_in_child; +{ + char *pathname; + int fd, result; + pid_t old_pid, pid; +#if defined (HAVE_DEV_FD) + int parent_pipe_fd, child_pipe_fd; + int fildes[2]; +#endif /* HAVE_DEV_FD */ +#if defined (JOB_CONTROL) + pid_t old_pipeline_pgrp; +#endif + + if (!string || !*string || wordexp_only) + return ((char *)NULL); + +#if !defined (HAVE_DEV_FD) + pathname = make_named_pipe (); +#else /* HAVE_DEV_FD */ + if (pipe (fildes) < 0) + { + sys_error (_("cannot make pipe for process substitution")); + return ((char *)NULL); + } + /* If OPEN_FOR_READ_IN_CHILD == 1, we want to use the write end of + the pipe in the parent, otherwise the read end. */ + parent_pipe_fd = fildes[open_for_read_in_child]; + child_pipe_fd = fildes[1 - open_for_read_in_child]; + /* Move the parent end of the pipe to some high file descriptor, to + avoid clashes with FDs used by the script. */ + parent_pipe_fd = move_to_high_fd (parent_pipe_fd, 1, 64); + + pathname = make_dev_fd_filename (parent_pipe_fd); +#endif /* HAVE_DEV_FD */ + + if (!pathname) + { + sys_error (_("cannot make pipe for process substitution")); + return ((char *)NULL); + } + + old_pid = last_made_pid; + +#if defined (JOB_CONTROL) + old_pipeline_pgrp = pipeline_pgrp; + pipeline_pgrp = shell_pgrp; + save_pipeline (1); +#endif /* JOB_CONTROL */ + + pid = make_child ((char *)NULL, 1); + if (pid == 0) + { + reset_terminating_signals (); /* XXX */ + free_pushed_string_input (); + /* Cancel traps, in trap.c. */ + restore_original_signals (); + setup_async_signals (); + subshell_environment |= SUBSHELL_COMSUB; + } + +#if defined (JOB_CONTROL) + set_sigchld_handler (); + stop_making_children (); + pipeline_pgrp = old_pipeline_pgrp; +#endif /* JOB_CONTROL */ + + if (pid < 0) + { + sys_error (_("cannot make child for process substitution")); + free (pathname); +#if defined (HAVE_DEV_FD) + close (parent_pipe_fd); + close (child_pipe_fd); +#endif /* HAVE_DEV_FD */ + return ((char *)NULL); + } + + if (pid > 0) + { +#if defined (JOB_CONTROL) + restore_pipeline (1); +#endif + +#if !defined (HAVE_DEV_FD) + fifo_list[nfifo-1].proc = pid; +#endif + + last_made_pid = old_pid; + +#if defined (JOB_CONTROL) && defined (PGRP_PIPE) + close_pgrp_pipe (); +#endif /* JOB_CONTROL && PGRP_PIPE */ + +#if defined (HAVE_DEV_FD) + close (child_pipe_fd); +#endif /* HAVE_DEV_FD */ + + return (pathname); + } + + set_sigint_handler (); + +#if defined (JOB_CONTROL) + set_job_control (0); +#endif /* JOB_CONTROL */ + +#if !defined (HAVE_DEV_FD) + /* Open the named pipe in the child. */ + fd = open (pathname, open_for_read_in_child ? O_RDONLY|O_NONBLOCK : O_WRONLY); + if (fd < 0) + { + /* Two separate strings for ease of translation. */ + if (open_for_read_in_child) + sys_error (_("cannot open named pipe %s for reading"), pathname); + else + sys_error (_("cannot open named pipe %s for writing"), pathname); + + exit (127); + } + if (open_for_read_in_child) + { + if (sh_unset_nodelay_mode (fd) < 0) + { + sys_error (_("cannot reset nodelay mode for fd %d"), fd); + exit (127); + } + } +#else /* HAVE_DEV_FD */ + fd = child_pipe_fd; +#endif /* HAVE_DEV_FD */ + + if (dup2 (fd, open_for_read_in_child ? 0 : 1) < 0) + { + sys_error (_("cannot duplicate named pipe %s as fd %d"), pathname, + open_for_read_in_child ? 0 : 1); + exit (127); + } + + if (fd != (open_for_read_in_child ? 0 : 1)) + close (fd); + + /* Need to close any files that this process has open to pipes inherited + from its parent. */ + if (current_fds_to_close) + { + close_fd_bitmap (current_fds_to_close); + current_fds_to_close = (struct fd_bitmap *)NULL; + } + +#if defined (HAVE_DEV_FD) + /* Make sure we close the parent's end of the pipe and clear the slot + in the fd list so it is not closed later, if reallocated by, for + instance, pipe(2). */ + close (parent_pipe_fd); + dev_fd_list[parent_pipe_fd] = 0; +#endif /* HAVE_DEV_FD */ + + result = parse_and_execute (string, "process substitution", (SEVAL_NONINT|SEVAL_NOHIST)); + +#if !defined (HAVE_DEV_FD) + /* Make sure we close the named pipe in the child before we exit. */ + close (open_for_read_in_child ? 0 : 1); +#endif /* !HAVE_DEV_FD */ + + exit (result); + /*NOTREACHED*/ +} +#endif /* PROCESS_SUBSTITUTION */ + +/***********************************/ +/* */ +/* Command Substitution */ +/* */ +/***********************************/ + +static char * +read_comsub (fd, quoted, rflag) + int fd, quoted; + int *rflag; +{ + char *istring, buf[128], *bufp; + int istring_index, istring_size, c, tflag; + ssize_t bufn; + + istring = (char *)NULL; + istring_index = istring_size = bufn = tflag = 0; + +#ifdef __CYGWIN__ + setmode (fd, O_TEXT); /* we don't want CR/LF, we want Unix-style */ +#endif + + /* Read the output of the command through the pipe. */ + while (1) + { + if (fd < 0) + break; + if (--bufn <= 0) + { + bufn = zread (fd, buf, sizeof (buf)); + if (bufn <= 0) + break; + bufp = buf; + } + c = *bufp++; + + if (c == 0) + { +#if 0 + internal_warning ("read_comsub: ignored null byte in input"); +#endif + continue; + } + + /* Add the character to ISTRING, possibly after resizing it. */ + RESIZE_MALLOCED_BUFFER (istring, istring_index, 2, istring_size, DEFAULT_ARRAY_SIZE); + + if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) /* || c == CTLESC || c == CTLNUL */) + istring[istring_index++] = CTLESC; + /* Escape CTLESC and CTLNUL in the output to protect those characters + from the rest of the word expansions (word splitting and globbing.) */ + else if (c == CTLESC) + { + tflag |= W_HASCTLESC; + istring[istring_index++] = CTLESC; + } + else if (c == CTLNUL) + istring[istring_index++] = CTLESC; + + istring[istring_index++] = c; + +#if 0 +#if defined (__CYGWIN__) + if (c == '\n' && istring_index > 1 && istring[istring_index - 2] == '\r') + { + istring_index--; + istring[istring_index - 1] = '\n'; + } +#endif +#endif + } + + if (istring) + istring[istring_index] = '\0'; + + /* If we read no output, just return now and save ourselves some + trouble. */ + if (istring_index == 0) + { + FREE (istring); + if (rflag) + *rflag = tflag; + return (char *)NULL; + } + + /* Strip trailing newlines from the output of the command. */ + if (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) + { + while (istring_index > 0) + { + if (istring[istring_index - 1] == '\n') + { + --istring_index; + + /* If the newline was quoted, remove the quoting char. */ + if (istring[istring_index - 1] == CTLESC) + --istring_index; + } + else + break; + } + istring[istring_index] = '\0'; + } + else + strip_trailing (istring, istring_index - 1, 1); + + if (rflag) + *rflag = tflag; + return istring; +} + +/* Perform command substitution on STRING. This returns a WORD_DESC * with the + contained string possibly quoted. */ +WORD_DESC * +command_substitute (string, quoted) + char *string; + int quoted; +{ + pid_t pid, old_pid, old_pipeline_pgrp, old_async_pid; + char *istring; + int result, fildes[2], function_value, pflags, rc, tflag; + WORD_DESC *ret; + + istring = (char *)NULL; + + /* Don't fork () if there is no need to. In the case of no command to + run, just return NULL. */ + if (!string || !*string || (string[0] == '\n' && !string[1])) + return ((WORD_DESC *)NULL); + + if (wordexp_only && read_but_dont_execute) + { + last_command_exit_value = 125; + jump_to_top_level (EXITPROG); + } + + /* We're making the assumption here that the command substitution will + eventually run a command from the file system. Since we'll run + maybe_make_export_env in this subshell before executing that command, + the parent shell and any other shells it starts will have to remake + the environment. If we make it before we fork, other shells won't + have to. Don't bother if we have any temporary variable assignments, + though, because the export environment will be remade after this + command completes anyway, but do it if all the words to be expanded + are variable assignments. */ + if (subst_assign_varlist == 0 || garglist == 0) + maybe_make_export_env (); /* XXX */ + + /* Flags to pass to parse_and_execute() */ + pflags = interactive ? SEVAL_RESETLINE : 0; + + /* Pipe the output of executing STRING into the current shell. */ + if (pipe (fildes) < 0) + { + sys_error (_("cannot make pipe for command substitution")); + goto error_exit; + } + + old_pid = last_made_pid; +#if defined (JOB_CONTROL) + old_pipeline_pgrp = pipeline_pgrp; + /* Don't reset the pipeline pgrp if we're already a subshell in a pipeline. */ + if ((subshell_environment & SUBSHELL_PIPE) == 0) + pipeline_pgrp = shell_pgrp; + cleanup_the_pipeline (); +#endif /* JOB_CONTROL */ + + old_async_pid = last_asynchronous_pid; + pid = make_child ((char *)NULL, subshell_environment&SUBSHELL_ASYNC); + last_asynchronous_pid = old_async_pid; + + if (pid == 0) + /* Reset the signal handlers in the child, but don't free the + trap strings. */ + reset_signal_handlers (); + +#if defined (JOB_CONTROL) + set_sigchld_handler (); + stop_making_children (); + pipeline_pgrp = old_pipeline_pgrp; +#else + stop_making_children (); +#endif /* JOB_CONTROL */ + + if (pid < 0) + { + sys_error (_("cannot make child for command substitution")); + error_exit: + + FREE (istring); + close (fildes[0]); + close (fildes[1]); + return ((WORD_DESC *)NULL); + } + + if (pid == 0) + { + set_sigint_handler (); /* XXX */ + + free_pushed_string_input (); + + if (dup2 (fildes[1], 1) < 0) + { + sys_error (_("command_substitute: cannot duplicate pipe as fd 1")); + exit (EXECUTION_FAILURE); + } + + /* If standard output is closed in the parent shell + (such as after `exec >&-'), file descriptor 1 will be + the lowest available file descriptor, and end up in + fildes[0]. This can happen for stdin and stderr as well, + but stdout is more important -- it will cause no output + to be generated from this command. */ + if ((fildes[1] != fileno (stdin)) && + (fildes[1] != fileno (stdout)) && + (fildes[1] != fileno (stderr))) + close (fildes[1]); + + if ((fildes[0] != fileno (stdin)) && + (fildes[0] != fileno (stdout)) && + (fildes[0] != fileno (stderr))) + close (fildes[0]); + + /* The currently executing shell is not interactive. */ + interactive = 0; + + /* This is a subshell environment. */ + subshell_environment |= SUBSHELL_COMSUB; + + /* When not in POSIX mode, command substitution does not inherit + the -e flag. */ + if (posixly_correct == 0) + exit_immediately_on_error = 0; + + remove_quoted_escapes (string); + + startup_state = 2; /* see if we can avoid a fork */ + /* Give command substitution a place to jump back to on failure, + so we don't go back up to main (). */ + result = setjmp (top_level); + + /* If we're running a command substitution inside a shell function, + trap `return' so we don't return from the function in the subshell + and go off to never-never land. */ + if (result == 0 && return_catch_flag) + function_value = setjmp (return_catch); + else + function_value = 0; + + if (result == ERREXIT) + rc = last_command_exit_value; + else if (result == EXITPROG) + rc = last_command_exit_value; + else if (result) + rc = EXECUTION_FAILURE; + else if (function_value) + rc = return_catch_value; + else + { + subshell_level++; + rc = parse_and_execute (string, "command substitution", pflags|SEVAL_NOHIST); + subshell_level--; + } + + last_command_exit_value = rc; + rc = run_exit_trap (); +#if defined (PROCESS_SUBSTITUTION) + unlink_fifo_list (); +#endif + exit (rc); + } + else + { +#if defined (JOB_CONTROL) && defined (PGRP_PIPE) + close_pgrp_pipe (); +#endif /* JOB_CONTROL && PGRP_PIPE */ + + close (fildes[1]); + + tflag = 0; + istring = read_comsub (fildes[0], quoted, &tflag); + + close (fildes[0]); + + current_command_subst_pid = pid; + last_command_exit_value = wait_for (pid); + last_command_subst_pid = pid; + last_made_pid = old_pid; + +#if defined (JOB_CONTROL) + /* If last_command_exit_value > 128, then the substituted command + was terminated by a signal. If that signal was SIGINT, then send + SIGINT to ourselves. This will break out of loops, for instance. */ + if (last_command_exit_value == (128 + SIGINT) && last_command_exit_signal == SIGINT) + kill (getpid (), SIGINT); + + /* wait_for gives the terminal back to shell_pgrp. If some other + process group should have it, give it away to that group here. + pipeline_pgrp is non-zero only while we are constructing a + pipline, so what we are concerned about is whether or not that + pipeline was started in the background. A pipeline started in + the background should never get the tty back here. */ +#if 0 + if (interactive && pipeline_pgrp != (pid_t)0 && pipeline_pgrp != last_asynchronous_pid) +#else + if (interactive && pipeline_pgrp != (pid_t)0 && (subshell_environment & SUBSHELL_ASYNC) == 0) +#endif + give_terminal_to (pipeline_pgrp, 0); +#endif /* JOB_CONTROL */ + + ret = alloc_word_desc (); + ret->word = istring; + ret->flags = tflag; + + return ret; + } +} + +/******************************************************** + * * + * Utility functions for parameter expansion * + * * + ********************************************************/ + +#if defined (ARRAY_VARS) + +static arrayind_t +array_length_reference (s) + char *s; +{ + int len; + arrayind_t ind; + char *t, c; + ARRAY *array; + SHELL_VAR *var; + + var = array_variable_part (s, &t, &len); + + /* If unbound variables should generate an error, report one and return + failure. */ + if ((var == 0 || array_p (var) == 0) && unbound_vars_is_error) + { + c = *--t; + *t = '\0'; + err_unboundvar (s); + *t = c; + return (-1); + } + else if (var == 0) + return 0; + + /* We support a couple of expansions for variables that are not arrays. + We'll return the length of the value for v[0], and 1 for v[@] or + v[*]. Return 0 for everything else. */ + + array = array_p (var) ? array_cell (var) : (ARRAY *)NULL; + + if (ALL_ELEMENT_SUB (t[0]) && t[1] == ']') + return (array_p (var) ? array_num_elements (array) : 1); + + ind = array_expand_index (t, len); + if (ind < 0) + { + err_badarraysub (t); + return (-1); + } + + if (array_p (var)) + t = array_reference (array, ind); + else + t = (ind == 0) ? value_cell (var) : (char *)NULL; + + len = STRLEN (t); + return (len); +} +#endif /* ARRAY_VARS */ + +static int +valid_brace_expansion_word (name, var_is_special) + char *name; + int var_is_special; +{ + if (DIGIT (*name) && all_digits (name)) + return 1; + else if (var_is_special) + return 1; +#if defined (ARRAY_VARS) + else if (valid_array_reference (name)) + return 1; +#endif /* ARRAY_VARS */ + else if (legal_identifier (name)) + return 1; + else + return 0; +} + +static int +chk_atstar (name, quoted, quoted_dollar_atp, contains_dollar_at) + char *name; + int quoted; + int *quoted_dollar_atp, *contains_dollar_at; +{ + char *temp1; + + if (name == 0) + { + if (quoted_dollar_atp) + *quoted_dollar_atp = 0; + if (contains_dollar_at) + *contains_dollar_at = 0; + return 0; + } + + /* check for $@ and $* */ + if (name[0] == '@' && name[1] == 0) + { + if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) && quoted_dollar_atp) + *quoted_dollar_atp = 1; + if (contains_dollar_at) + *contains_dollar_at = 1; + return 1; + } + else if (name[0] == '*' && name[1] == '\0' && quoted == 0) + { + if (contains_dollar_at) + *contains_dollar_at = 1; + return 1; + } + + /* Now check for ${array[@]} and ${array[*]} */ +#if defined (ARRAY_VARS) + else if (valid_array_reference (name)) + { + temp1 = xstrchr (name, '['); + if (temp1 && temp1[1] == '@' && temp1[2] == ']') + { + if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) && quoted_dollar_atp) + *quoted_dollar_atp = 1; + if (contains_dollar_at) + *contains_dollar_at = 1; + return 1; + } /* [ */ + /* ${array[*]}, when unquoted, should be treated like ${array[@]}, + which should result in separate words even when IFS is unset. */ + if (temp1 && temp1[1] == '*' && temp1[2] == ']' && quoted == 0) + { + if (contains_dollar_at) + *contains_dollar_at = 1; + return 1; + } + } +#endif + return 0; +} + +/* Parameter expand NAME, and return a new string which is the expansion, + or NULL if there was no expansion. + VAR_IS_SPECIAL is non-zero if NAME is one of the special variables in + the shell, e.g., "@", "$", "*", etc. QUOTED, if non-zero, means that + NAME was found inside of a double-quoted expression. */ +static WORD_DESC * +parameter_brace_expand_word (name, var_is_special, quoted) + char *name; + int var_is_special, quoted; +{ + WORD_DESC *ret; + char *temp, *tt; + intmax_t arg_index; + SHELL_VAR *var; + int atype; + + ret = 0; + temp = 0; + + /* Handle multiple digit arguments, as in ${11}. */ + if (legal_number (name, &arg_index)) + { + tt = get_dollar_var_value (arg_index); + if (tt) + temp = (*tt && (quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT))) + ? quote_string (tt) + : quote_escapes (tt); + else + temp = (char *)NULL; + FREE (tt); + } + else if (var_is_special) /* ${@} */ + { + int sindex; + tt = (char *)xmalloc (2 + strlen (name)); + tt[sindex = 0] = '$'; + strcpy (tt + 1, name); + + ret = param_expand (tt, &sindex, quoted, (int *)NULL, (int *)NULL, + (int *)NULL, (int *)NULL, 0); + free (tt); + } +#if defined (ARRAY_VARS) + else if (valid_array_reference (name)) + { + temp = array_value (name, quoted, &atype); + if (atype == 0 && temp) + temp = (*temp && (quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT))) + ? quote_string (temp) + : quote_escapes (temp); + } +#endif + else if (var = find_variable (name)) + { + if (var_isset (var) && invisible_p (var) == 0) + { +#if defined (ARRAY_VARS) + temp = array_p (var) ? array_reference (array_cell (var), 0) : value_cell (var); +#else + temp = value_cell (var); +#endif + + if (temp) + temp = (*temp && (quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT))) + ? quote_string (temp) + : quote_escapes (temp); + } + else + temp = (char *)NULL; + } + else + temp = (char *)NULL; + + if (ret == 0) + { + ret = alloc_word_desc (); + ret->word = temp; + } + return ret; +} + +/* Expand an indirect reference to a variable: ${!NAME} expands to the + value of the variable whose name is the value of NAME. */ +static WORD_DESC * +parameter_brace_expand_indir (name, var_is_special, quoted, quoted_dollar_atp, contains_dollar_at) + char *name; + int var_is_special, quoted; + int *quoted_dollar_atp, *contains_dollar_at; +{ + char *temp, *t; + WORD_DESC *w; + + w = parameter_brace_expand_word (name, var_is_special, quoted); + t = w->word; + /* Have to dequote here if necessary */ + if (t) + { + temp = (quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT)) + ? dequote_string (t) + : dequote_escapes (t); + free (t); + t = temp; + } + dispose_word_desc (w); + + chk_atstar (t, quoted, quoted_dollar_atp, contains_dollar_at); + if (t == 0) + return (WORD_DESC *)NULL; + + w = parameter_brace_expand_word (t, SPECIAL_VAR(t, 0), quoted); + free (t); + + return w; +} + +/* Expand the right side of a parameter expansion of the form ${NAMEcVALUE}, + depending on the value of C, the separating character. C can be one of + "-", "+", or "=". QUOTED is true if the entire brace expression occurs + between double quotes. */ +static WORD_DESC * +parameter_brace_expand_rhs (name, value, c, quoted, qdollaratp, hasdollarat) + char *name, *value; + int c, quoted, *qdollaratp, *hasdollarat; +{ + WORD_DESC *w; + WORD_LIST *l; + char *t, *t1, *temp; + int hasdol; + + /* If the entire expression is between double quotes, we want to treat + the value as a double-quoted string, with the exception that we strip + embedded unescaped double quotes (for sh backwards compatibility). */ + if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) && *value) + { + hasdol = 0; + temp = string_extract_double_quoted (value, &hasdol, 1); + } + else + temp = value; + + w = alloc_word_desc (); + hasdol = 0; + /* XXX was 0 not quoted */ + l = *temp ? expand_string_for_rhs (temp, quoted, &hasdol, (int *)NULL) + : (WORD_LIST *)0; + if (hasdollarat) + *hasdollarat = hasdol || (l && l->next); + if (temp != value) + free (temp); + if (l) + { + /* The expansion of TEMP returned something. We need to treat things + slightly differently if HASDOL is non-zero. If we have "$@", the + individual words have already been quoted. We need to turn them + into a string with the words separated by the first character of + $IFS without any additional quoting, so string_list_dollar_at won't + do the right thing. We use string_list_dollar_star instead. */ + temp = (hasdol || l->next) ? string_list_dollar_star (l) : string_list (l); + + /* If l->next is not null, we know that TEMP contained "$@", since that + is the only expansion that creates more than one word. */ + if (qdollaratp && ((hasdol && quoted) || l->next)) + *qdollaratp = 1; + dispose_words (l); + } + else if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) && hasdol) + { + /* The brace expansion occurred between double quotes and there was + a $@ in TEMP. It does not matter if the $@ is quoted, as long as + it does not expand to anything. In this case, we want to return + a quoted empty string. */ + temp = make_quoted_char ('\0'); + w->flags |= W_HASQUOTEDNULL; + } + else + temp = (char *)NULL; + + if (c == '-' || c == '+') + { + w->word = temp; + return w; + } + + /* c == '=' */ + t = temp ? savestring (temp) : savestring (""); + t1 = dequote_string (t); + free (t); +#if defined (ARRAY_VARS) + if (valid_array_reference (name)) + assign_array_element (name, t1, 0); + else +#endif /* ARRAY_VARS */ + bind_variable (name, t1, 0); + free (t1); + + w->word = temp; + return w; +} + +/* Deal with the right hand side of a ${name:?value} expansion in the case + that NAME is null or not set. If VALUE is non-null it is expanded and + used as the error message to print, otherwise a standard message is + printed. */ +static void +parameter_brace_expand_error (name, value) + char *name, *value; +{ + WORD_LIST *l; + char *temp; + + if (value && *value) + { + l = expand_string (value, 0); + temp = string_list (l); + report_error ("%s: %s", name, temp ? temp : ""); /* XXX was value not "" */ + FREE (temp); + dispose_words (l); + } + else + report_error (_("%s: parameter null or not set"), name); + + /* Free the data we have allocated during this expansion, since we + are about to longjmp out. */ + free (name); + FREE (value); +} + +/* Return 1 if NAME is something for which parameter_brace_expand_length is + OK to do. */ +static int +valid_length_expression (name) + char *name; +{ + return (name[1] == '\0' || /* ${#} */ + ((sh_syntaxtab[(unsigned char) name[1]] & CSPECVAR) && name[2] == '\0') || /* special param */ + (DIGIT (name[1]) && all_digits (name + 1)) || /* ${#11} */ +#if defined (ARRAY_VARS) + valid_array_reference (name + 1) || /* ${#a[7]} */ +#endif + legal_identifier (name + 1)); /* ${#PS1} */ +} + +#if defined (HANDLE_MULTIBYTE) +size_t +mbstrlen (s) + const char *s; +{ + size_t clen, nc; + mbstate_t mbs, mbsbak; + + nc = 0; + memset (&mbs, 0, sizeof (mbs)); + mbsbak = mbs; + while ((clen = mbrlen(s, MB_CUR_MAX, &mbs)) != 0) + { + if (MB_INVALIDCH(clen)) + { + clen = 1; /* assume single byte */ + mbs = mbsbak; + } + + s += clen; + nc++; + mbsbak = mbs; + } + return nc; +} +#endif + + +/* Handle the parameter brace expansion that requires us to return the + length of a parameter. */ +static intmax_t +parameter_brace_expand_length (name) + char *name; +{ + char *t, *newname; + intmax_t number, arg_index; + WORD_LIST *list; +#if defined (ARRAY_VARS) + SHELL_VAR *var; +#endif + + if (name[1] == '\0') /* ${#} */ + number = number_of_args (); + else if ((name[1] == '@' || name[1] == '*') && name[2] == '\0') /* ${#@}, ${#*} */ + number = number_of_args (); + else if ((sh_syntaxtab[(unsigned char) name[1]] & CSPECVAR) && name[2] == '\0') + { + /* Take the lengths of some of the shell's special parameters. */ + switch (name[1]) + { + case '-': + t = which_set_flags (); + break; + case '?': + t = itos (last_command_exit_value); + break; + case '$': + t = itos (dollar_dollar_pid); + break; + case '!': + if (last_asynchronous_pid == NO_PID) + t = (char *)NULL; + else + t = itos (last_asynchronous_pid); + break; + case '#': + t = itos (number_of_args ()); + break; + } + number = STRLEN (t); + FREE (t); + } +#if defined (ARRAY_VARS) + else if (valid_array_reference (name + 1)) + number = array_length_reference (name + 1); +#endif /* ARRAY_VARS */ + else + { + number = 0; + + if (legal_number (name + 1, &arg_index)) /* ${#1} */ + { + t = get_dollar_var_value (arg_index); + number = MB_STRLEN (t); + FREE (t); + } +#if defined (ARRAY_VARS) + else if ((var = find_variable (name + 1)) && (invisible_p (var) == 0) && array_p (var)) + { + t = array_reference (array_cell (var), 0); + number = MB_STRLEN (t); + } +#endif + else /* ${#PS1} */ + { + newname = savestring (name); + newname[0] = '$'; + list = expand_string (newname, Q_DOUBLE_QUOTES); + t = list ? string_list (list) : (char *)NULL; + free (newname); + if (list) + dispose_words (list); + + number = MB_STRLEN (t); + FREE (t); + } + } + + return (number); +} + +/* Skip characters in SUBSTR until DELIM. SUBSTR is an arithmetic expression, + so we do some ad-hoc parsing of an arithmetic expression to find + the first DELIM, instead of using strchr(3). Two rules: + 1. If the substring contains a `(', read until closing `)'. + 2. If the substring contains a `?', read past one `:' for each `?'. +*/ + +static char * +skiparith (substr, delim) + char *substr; + int delim; +{ + size_t sublen; + int skipcol, pcount, i; + DECLARE_MBSTATE; + + sublen = strlen (substr); + i = skipcol = pcount = 0; + while (substr[i]) + { + /* Balance parens */ + if (substr[i] == LPAREN) + { + pcount++; + i++; + continue; + } + if (substr[i] == RPAREN && pcount) + { + pcount--; + i++; + continue; + } + if (pcount) + { + ADVANCE_CHAR (substr, sublen, i); + continue; + } + + /* Skip one `:' for each `?' */ + if (substr[i] == ':' && skipcol) + { + skipcol--; + i++; + continue; + } + if (substr[i] == delim) + break; + if (substr[i] == '?') + { + skipcol++; + i++; + continue; + } + ADVANCE_CHAR (substr, sublen, i); + } + + return (substr + i); +} + +/* Verify and limit the start and end of the desired substring. If + VTYPE == 0, a regular shell variable is being used; if it is 1, + then the positional parameters are being used; if it is 2, then + VALUE is really a pointer to an array variable that should be used. + Return value is 1 if both values were OK, 0 if there was a problem + with an invalid expression, or -1 if the values were out of range. */ +static int +verify_substring_values (value, substr, vtype, e1p, e2p) + char *value, *substr; + int vtype; + intmax_t *e1p, *e2p; +{ + char *t, *temp1, *temp2; + arrayind_t len; + int expok; +#if defined (ARRAY_VARS) + ARRAY *a; +#endif + + /* duplicate behavior of strchr(3) */ + t = skiparith (substr, ':'); + if (*t && *t == ':') + *t = '\0'; + else + t = (char *)0; + + temp1 = expand_arith_string (substr, Q_DOUBLE_QUOTES); + *e1p = evalexp (temp1, &expok); + free (temp1); + if (expok == 0) + return (0); + + len = -1; /* paranoia */ + switch (vtype) + { + case VT_VARIABLE: + case VT_ARRAYMEMBER: + len = MB_STRLEN (value); + break; + case VT_POSPARMS: + len = number_of_args () + 1; + if (*e1p == 0) + len++; /* add one arg if counting from $0 */ + break; +#if defined (ARRAY_VARS) + case VT_ARRAYVAR: + a = (ARRAY *)value; + /* For arrays, the first value deals with array indices. Negative + offsets count from one past the array's maximum index. */ + len = array_max_index (a) + (*e1p < 0); /* arrays index from 0 to n - 1 */ + break; +#endif + } + + if (len == -1) /* paranoia */ + return -1; + + if (*e1p < 0) /* negative offsets count from end */ + *e1p += len; + + if (*e1p > len || *e1p < 0) + return (-1); + +#if defined (ARRAY_VARS) + /* For arrays, the second offset deals with the number of elements. */ + if (vtype == VT_ARRAYVAR) + len = array_num_elements (a); +#endif + + if (t) + { + t++; + temp2 = savestring (t); + temp1 = expand_arith_string (temp2, Q_DOUBLE_QUOTES); + free (temp2); + t[-1] = ':'; + *e2p = evalexp (temp1, &expok); + free (temp1); + if (expok == 0) + return (0); + if (*e2p < 0) + { + internal_error (_("%s: substring expression < 0"), t); + return (0); + } +#if defined (ARRAY_VARS) + /* In order to deal with sparse arrays, push the intelligence about how + to deal with the number of elements desired down to the array- + specific functions. */ + if (vtype != VT_ARRAYVAR) +#endif + { + *e2p += *e1p; /* want E2 chars starting at E1 */ + if (*e2p > len) + *e2p = len; + } + } + else + *e2p = len; + + return (1); +} + +/* Return the type of variable specified by VARNAME (simple variable, + positional param, or array variable). Also return the value specified + by VARNAME (value of a variable or a reference to an array element). + If this returns VT_VARIABLE, the caller assumes that CTLESC and CTLNUL + characters in the value are quoted with CTLESC and takes appropriate + steps. For convenience, *VALP is set to the dequoted VALUE. */ +static int +get_var_and_type (varname, value, quoted, varp, valp) + char *varname, *value; + int quoted; + SHELL_VAR **varp; + char **valp; +{ + int vtype; + char *temp; +#if defined (ARRAY_VARS) + SHELL_VAR *v; +#endif + + /* This sets vtype to VT_VARIABLE or VT_POSPARMS */ + vtype = (varname[0] == '@' || varname[0] == '*') && varname[1] == '\0'; + if (vtype == VT_POSPARMS && varname[0] == '*') + vtype |= VT_STARSUB; + *varp = (SHELL_VAR *)NULL; + +#if defined (ARRAY_VARS) + if (valid_array_reference (varname)) + { + v = array_variable_part (varname, &temp, (int *)0); + if (v && array_p (v)) + { /* [ */ + if (ALL_ELEMENT_SUB (temp[0]) && temp[1] == ']') + { + vtype = VT_ARRAYVAR; + if (temp[0] == '*') + vtype |= VT_STARSUB; + *valp = (char *)array_cell (v); + } + else + { + vtype = VT_ARRAYMEMBER; + *valp = array_value (varname, 1, (int *)NULL); + } + *varp = v; + } + else if (v && (ALL_ELEMENT_SUB (temp[0]) && temp[1] == ']')) + { + vtype = VT_VARIABLE; + *varp = v; + if (quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT)) + *valp = dequote_string (value); + else + *valp = dequote_escapes (value); + } + else + return -1; + } + else if ((v = find_variable (varname)) && (invisible_p (v) == 0) && array_p (v)) + { + vtype = VT_ARRAYMEMBER; + *varp = v; + *valp = array_reference (array_cell (v), 0); + } + else +#endif + { + if (value && vtype == VT_VARIABLE) + { + if (quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT)) + *valp = dequote_string (value); + else + *valp = dequote_escapes (value); + } + else + *valp = value; + } + + return vtype; +} + +/******************************************************/ +/* */ +/* Functions to extract substrings of variable values */ +/* */ +/******************************************************/ + +#if defined (HANDLE_MULTIBYTE) +/* Character-oriented rather than strictly byte-oriented substrings. S and + E, rather being strict indices into STRING, indicate character (possibly + multibyte character) positions that require calculation. + Used by the ${param:offset[:length]} expansion. */ +static char * +mb_substring (string, s, e) + char *string; + int s, e; +{ + char *tt; + int start, stop, i, slen; + DECLARE_MBSTATE; + + start = 0; + /* Don't need string length in ADVANCE_CHAR unless multibyte chars possible. */ + slen = (MB_CUR_MAX > 1) ? STRLEN (string) : 0; + + i = s; + while (string[start] && i--) + ADVANCE_CHAR (string, slen, start); + stop = start; + i = e - s; + while (string[stop] && i--) + ADVANCE_CHAR (string, slen, stop); + tt = substring (string, start, stop); + return tt; +} +#endif + +/* Process a variable substring expansion: ${name:e1[:e2]}. If VARNAME + is `@', use the positional parameters; otherwise, use the value of + VARNAME. If VARNAME is an array variable, use the array elements. */ + +static char * +parameter_brace_substring (varname, value, substr, quoted) + char *varname, *value, *substr; + int quoted; +{ + intmax_t e1, e2; + int vtype, r, starsub; + char *temp, *val, *tt, *oname; + SHELL_VAR *v; + + if (value == 0) + return ((char *)NULL); + + oname = this_command_name; + this_command_name = varname; + + vtype = get_var_and_type (varname, value, quoted, &v, &val); + if (vtype == -1) + { + this_command_name = oname; + return ((char *)NULL); + } + + starsub = vtype & VT_STARSUB; + vtype &= ~VT_STARSUB; + + r = verify_substring_values (val, substr, vtype, &e1, &e2); + this_command_name = oname; + if (r <= 0) + return ((r == 0) ? &expand_param_error : (char *)NULL); + + switch (vtype) + { + case VT_VARIABLE: + case VT_ARRAYMEMBER: +#if defined (HANDLE_MULTIBYTE) + if (MB_CUR_MAX > 1) + tt = mb_substring (val, e1, e2); + else +#endif + tt = substring (val, e1, e2); + + if (vtype == VT_VARIABLE) + FREE (val); + if (quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT)) + temp = quote_string (tt); + else + temp = tt ? quote_escapes (tt) : (char *)NULL; + FREE (tt); + break; + case VT_POSPARMS: + tt = pos_params (varname, e1, e2, quoted); + if ((quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT)) == 0) + { + temp = tt ? quote_escapes (tt) : (char *)NULL; + FREE (tt); + } + else + temp = tt; + break; +#if defined (ARRAY_VARS) + case VT_ARRAYVAR: + /* We want E2 to be the number of elements desired (arrays can be sparse, + so verify_substring_values just returns the numbers specified and we + rely on array_subrange to understand how to deal with them). */ + tt = array_subrange (array_cell (v), e1, e2, starsub, quoted); + if ((quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT)) == 0) + { + temp = tt ? quote_escapes (tt) : (char *)NULL; + FREE (tt); + } + else + temp = tt; + break; +#endif + default: + temp = (char *)NULL; + } + + return temp; +} + +/****************************************************************/ +/* */ +/* Functions to perform pattern substitution on variable values */ +/* */ +/****************************************************************/ + +char * +pat_subst (string, pat, rep, mflags) + char *string, *pat, *rep; + int mflags; +{ + char *ret, *s, *e, *str; + int rsize, rptr, l, replen, mtype; + + mtype = mflags & MATCH_TYPEMASK; + + /* Special cases: + * 1. A null pattern with mtype == MATCH_BEG means to prefix STRING + * with REP and return the result. + * 2. A null pattern with mtype == MATCH_END means to append REP to + * STRING and return the result. + */ + if ((pat == 0 || *pat == 0) && (mtype == MATCH_BEG || mtype == MATCH_END)) + { + replen = STRLEN (rep); + l = strlen (string); + ret = (char *)xmalloc (replen + l + 2); + if (replen == 0) + strcpy (ret, string); + else if (mtype == MATCH_BEG) + { + strcpy (ret, rep); + strcpy (ret + replen, string); + } + else + { + strcpy (ret, string); + strcpy (ret + l, rep); + } + return (ret); + } + + ret = (char *)xmalloc (rsize = 64); + ret[0] = '\0'; + + for (replen = STRLEN (rep), rptr = 0, str = string;;) + { + if (match_pattern (str, pat, mtype, &s, &e) == 0) + break; + l = s - str; + RESIZE_MALLOCED_BUFFER (ret, rptr, (l + replen), rsize, 64); + + /* OK, now copy the leading unmatched portion of the string (from + str to s) to ret starting at rptr (the current offset). Then copy + the replacement string at ret + rptr + (s - str). Increment + rptr (if necessary) and str and go on. */ + if (l) + { + strncpy (ret + rptr, str, l); + rptr += l; + } + if (replen) + { + strncpy (ret + rptr, rep, replen); + rptr += replen; + } + str = e; /* e == end of match */ + + if (((mflags & MATCH_GLOBREP) == 0) || mtype != MATCH_ANY) + break; + + if (s == e) + e++, str++; /* avoid infinite recursion on zero-length match */ + } + + /* Now copy the unmatched portion of the input string */ + if (*str) + { + RESIZE_MALLOCED_BUFFER (ret, rptr, STRLEN(str) + 1, rsize, 64); + strcpy (ret + rptr, str); + } + else + ret[rptr] = '\0'; + + return ret; +} + +/* Do pattern match and replacement on the positional parameters. */ +static char * +pos_params_pat_subst (string, pat, rep, mflags) + char *string, *pat, *rep; + int mflags; +{ + WORD_LIST *save, *params; + WORD_DESC *w; + char *ret; + + save = params = list_rest_of_args (); + if (save == 0) + return ((char *)NULL); + + for ( ; params; params = params->next) + { + ret = pat_subst (params->word->word, pat, rep, mflags); + w = alloc_word_desc (); + w->word = ret ? ret : savestring (""); + dispose_word (params->word); + params->word = w; + } + + if ((mflags & (MATCH_QUOTED|MATCH_STARSUB)) == (MATCH_QUOTED|MATCH_STARSUB)) + ret = string_list_dollar_star (quote_list (save)); + else + ret = string_list ((mflags & MATCH_QUOTED) ? quote_list (save) : save); + dispose_words (save); + + return (ret); +} + +/* Perform pattern substitution on VALUE, which is the expansion of + VARNAME. PATSUB is an expression supplying the pattern to match + and the string to substitute. QUOTED is a flags word containing + the type of quoting currently in effect. */ +static char * +parameter_brace_patsub (varname, value, patsub, quoted) + char *varname, *value, *patsub; + int quoted; +{ + int vtype, mflags, starsub; + char *val, *temp, *pat, *rep, *p, *lpatsub, *tt; + SHELL_VAR *v; + + if (value == 0) + return ((char *)NULL); + + this_command_name = varname; + + vtype = get_var_and_type (varname, value, quoted, &v, &val); + if (vtype == -1) + return ((char *)NULL); + + starsub = vtype & VT_STARSUB; + vtype &= ~VT_STARSUB; + + mflags = 0; + if (patsub && *patsub == '/') + { + mflags |= MATCH_GLOBREP; + patsub++; + } + + /* Malloc this because expand_string_if_necessary or one of the expansion + functions in its call chain may free it on a substitution error. */ + lpatsub = savestring (patsub); + + if (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) + mflags |= MATCH_QUOTED; + + if (starsub) + mflags |= MATCH_STARSUB; + + /* If the pattern starts with a `/', make sure we skip over it when looking + for the replacement delimiter. */ + if (rep = quoted_strchr ((*patsub == '/') ? lpatsub+1 : lpatsub, '/', ST_BACKSL)) + *rep++ = '\0'; + else + rep = (char *)NULL; + + if (rep && *rep == '\0') + rep = (char *)NULL; + + /* Perform the same expansions on the pattern as performed by the + pattern removal expansions. */ + pat = getpattern (lpatsub, quoted, 1); + + if (rep) + { + if ((mflags & MATCH_QUOTED) == 0) + rep = expand_string_if_necessary (rep, quoted, expand_string_unsplit); + else + rep = expand_string_to_string_internal (rep, quoted, expand_string_unsplit); + } + + /* ksh93 doesn't allow the match specifier to be a part of the expanded + pattern. This is an extension. Make sure we don't anchor the pattern + at the beginning or end of the string if we're doing global replacement, + though. */ + p = pat; + if (mflags & MATCH_GLOBREP) + mflags |= MATCH_ANY; + else if (pat && pat[0] == '#') + { + mflags |= MATCH_BEG; + p++; + } + else if (pat && pat[0] == '%') + { + mflags |= MATCH_END; + p++; + } + else + mflags |= MATCH_ANY; + + /* OK, we now want to substitute REP for PAT in VAL. If + flags & MATCH_GLOBREP is non-zero, the substitution is done + everywhere, otherwise only the first occurrence of PAT is + replaced. The pattern matching code doesn't understand + CTLESC quoting CTLESC and CTLNUL so we use the dequoted variable + values passed in (VT_VARIABLE) so the pattern substitution + code works right. We need to requote special chars after + we're done for VT_VARIABLE and VT_ARRAYMEMBER, and for the + other cases if QUOTED == 0, since the posparams and arrays + indexed by * or @ do special things when QUOTED != 0. */ + + switch (vtype) + { + case VT_VARIABLE: + case VT_ARRAYMEMBER: + temp = pat_subst (val, p, rep, mflags); + if (vtype == VT_VARIABLE) + FREE (val); + if (temp) + { + tt = quote_escapes (temp); + free (temp); + temp = tt; + } + break; + case VT_POSPARMS: + temp = pos_params_pat_subst (val, p, rep, mflags); + if (temp && (mflags & MATCH_QUOTED) == 0) + { + tt = quote_escapes (temp); + free (temp); + temp = tt; + } + break; +#if defined (ARRAY_VARS) + case VT_ARRAYVAR: + temp = array_patsub (array_cell (v), p, rep, mflags); + if (temp && (mflags & MATCH_QUOTED) == 0) + { + tt = quote_escapes (temp); + free (temp); + temp = tt; + } + break; +#endif + } + + FREE (pat); + FREE (rep); + free (lpatsub); + + return temp; +} + +/* Check for unbalanced parens in S, which is the contents of $(( ... )). If + any occur, this must be a nested command substitution, so return 0. + Otherwise, return 1. A valid arithmetic expression must always have a + ( before a matching ), so any cases where there are more right parens + means that this must not be an arithmetic expression, though the parser + will not accept it without a balanced total number of parens. */ +static int +chk_arithsub (s, len) + const char *s; + int len; +{ + int i, count; + DECLARE_MBSTATE; + + i = count = 0; + while (i < len) + { + if (s[i] == '(') + count++; + else if (s[i] == ')') + { + count--; + if (count < 0) + return 0; + } + + switch (s[i]) + { + default: + ADVANCE_CHAR (s, len, i); + break; + + case '\\': + i++; + if (s[i]) + ADVANCE_CHAR (s, len, i); + break; + + case '\'': + i = skip_single_quoted (s, len, ++i); + break; + + case '"': + i = skip_double_quoted ((char *)s, len, ++i); + break; + } + } + + return (count == 0); +} + +/****************************************************************/ +/* */ +/* Functions to perform parameter expansion on a string */ +/* */ +/****************************************************************/ + +/* ${[#][!]name[[:]#[#]%[%]-=?+[word][:e1[:e2]]]} */ +static WORD_DESC * +parameter_brace_expand (string, indexp, quoted, quoted_dollar_atp, contains_dollar_at) + char *string; + int *indexp, quoted, *quoted_dollar_atp, *contains_dollar_at; +{ + int check_nullness, var_is_set, var_is_null, var_is_special; + int want_substring, want_indir, want_patsub; + char *name, *value, *temp, *temp1; + WORD_DESC *tdesc, *ret; + int t_index, sindex, c, tflag; + intmax_t number; + + value = (char *)NULL; + var_is_set = var_is_null = var_is_special = check_nullness = 0; + want_substring = want_indir = want_patsub = 0; + + sindex = *indexp; + t_index = ++sindex; + /* ${#var} doesn't have any of the other parameter expansions on it. */ + if (string[t_index] == '#' && legal_variable_starter (string[t_index+1])) /* {{ */ + name = string_extract (string, &t_index, "}", EX_VARNAME); + else + name = string_extract (string, &t_index, "#%:-=?+/}", EX_VARNAME); + + ret = 0; + tflag = 0; + + /* If the name really consists of a special variable, then make sure + that we have the entire name. We don't allow indirect references + to special variables except `#', `?', `@' and `*'. */ + if ((sindex == t_index && + (string[t_index] == '-' || + string[t_index] == '?' || + string[t_index] == '#')) || + (sindex == t_index - 1 && string[sindex] == '!' && + (string[t_index] == '#' || + string[t_index] == '?' || + string[t_index] == '@' || + string[t_index] == '*'))) + { + t_index++; + free (name); + temp1 = string_extract (string, &t_index, "#%:-=?+/}", 0); + name = (char *)xmalloc (3 + (strlen (temp1))); + *name = string[sindex]; + if (string[sindex] == '!') + { + /* indirect reference of $#, $?, $@, or $* */ + name[1] = string[sindex + 1]; + strcpy (name + 2, temp1); + } + else + strcpy (name + 1, temp1); + free (temp1); + } + sindex = t_index; + + /* Find out what character ended the variable name. Then + do the appropriate thing. */ + if (c = string[sindex]) + sindex++; + + /* If c is followed by one of the valid parameter expansion + characters, move past it as normal. If not, assume that + a substring specification is being given, and do not move + past it. */ + if (c == ':' && VALID_PARAM_EXPAND_CHAR (string[sindex])) + { + check_nullness++; + if (c = string[sindex]) + sindex++; + } + else if (c == ':' && string[sindex] != RBRACE) + want_substring = 1; + else if (c == '/' && string[sindex] != RBRACE) + want_patsub = 1; + + /* Catch the valid and invalid brace expressions that made it through the + tests above. */ + /* ${#-} is a valid expansion and means to take the length of $-. + Similarly for ${#?} and ${##}... */ + if (name[0] == '#' && name[1] == '\0' && check_nullness == 0 && + VALID_SPECIAL_LENGTH_PARAM (c) && string[sindex] == RBRACE) + { + name = (char *)xrealloc (name, 3); + name[1] = c; + name[2] = '\0'; + c = string[sindex++]; + } + + /* ...but ${#%}, ${#:}, ${#=}, ${#+}, and ${#/} are errors. */ + if (name[0] == '#' && name[1] == '\0' && check_nullness == 0 && + member (c, "%:=+/") && string[sindex] == RBRACE) + { + temp = (char *)NULL; + goto bad_substitution; + } + + /* Indirect expansion begins with a `!'. A valid indirect expansion is + either a variable name, one of the positional parameters or a special + variable that expands to one of the positional parameters. */ + want_indir = *name == '!' && + (legal_variable_starter ((unsigned char)name[1]) || DIGIT (name[1]) + || VALID_INDIR_PARAM (name[1])); + + /* Determine the value of this variable. */ + + /* Check for special variables, directly referenced. */ + if (SPECIAL_VAR (name, want_indir)) + var_is_special++; + + /* Check for special expansion things, like the length of a parameter */ + if (*name == '#' && name[1]) + { + /* If we are not pointing at the character just after the + closing brace, then we haven't gotten all of the name. + Since it begins with a special character, this is a bad + substitution. Also check NAME for validity before trying + to go on. */ + if (string[sindex - 1] != RBRACE || (valid_length_expression (name) == 0)) + { + temp = (char *)NULL; + goto bad_substitution; + } + + number = parameter_brace_expand_length (name); + free (name); + + *indexp = sindex; + if (number < 0) + return (&expand_wdesc_error); + else + { + ret = alloc_word_desc (); + ret->word = itos (number); + return ret; + } + } + + /* ${@} is identical to $@. */ + if (name[0] == '@' && name[1] == '\0') + { + if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) && quoted_dollar_atp) + *quoted_dollar_atp = 1; + + if (contains_dollar_at) + *contains_dollar_at = 1; + } + + /* Process ${!PREFIX*} expansion. */ + if (want_indir && string[sindex - 1] == RBRACE && + (string[sindex - 2] == '*' || string[sindex - 2] == '@') && + legal_variable_starter ((unsigned char) name[1])) + { + char **x; + WORD_LIST *xlist; + + temp1 = savestring (name + 1); + number = strlen (temp1); + temp1[number - 1] = '\0'; + x = all_variables_matching_prefix (temp1); + xlist = strvec_to_word_list (x, 0, 0); + if (string[sindex - 2] == '*') + temp = string_list_dollar_star (xlist); + else + { + temp = string_list_dollar_at (xlist, quoted); + if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) && quoted_dollar_atp) + *quoted_dollar_atp = 1; + if (contains_dollar_at) + *contains_dollar_at = 1; + } + free (x); + free (xlist); + free (temp1); + *indexp = sindex; + + ret = alloc_word_desc (); + ret->word = temp; + return ret; + } + +#if defined (ARRAY_VARS) + /* Process ${!ARRAY[@]} and ${!ARRAY[*]} expansion. */ /* [ */ + if (want_indir && string[sindex - 1] == RBRACE && + string[sindex - 2] == ']' && valid_array_reference (name+1)) + { + char *x, *x1; + + temp1 = savestring (name + 1); + x = array_variable_name (temp1, &x1, (int *)0); /* [ */ + FREE (x); + if (ALL_ELEMENT_SUB (x1[0]) && x1[1] == ']') + { + temp = array_keys (temp1, quoted); + if (x1[0] == '@') + { + if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) && quoted_dollar_atp) + *quoted_dollar_atp = 1; + if (contains_dollar_at) + *contains_dollar_at = 1; + } + + free (temp1); + *indexp = sindex; + + ret = alloc_word_desc (); + ret->word = temp; + return ret; + } + + free (temp1); + } +#endif /* ARRAY_VARS */ + + /* Make sure that NAME is valid before trying to go on. */ + if (valid_brace_expansion_word (want_indir ? name + 1 : name, + var_is_special) == 0) + { + temp = (char *)NULL; + goto bad_substitution; + } + + if (want_indir) + tdesc = parameter_brace_expand_indir (name + 1, var_is_special, quoted, quoted_dollar_atp, contains_dollar_at); + else + tdesc = parameter_brace_expand_word (name, var_is_special, quoted); + + if (tdesc) + { + temp = tdesc->word; + tflag = tdesc->flags; + dispose_word_desc (tdesc); + } + else + temp = (char *)0; + +#if defined (ARRAY_VARS) + if (valid_array_reference (name)) + chk_atstar (name, quoted, quoted_dollar_atp, contains_dollar_at); +#endif + + var_is_set = temp != (char *)0; + var_is_null = check_nullness && (var_is_set == 0 || *temp == 0); + + /* Get the rest of the stuff inside the braces. */ + if (c && c != RBRACE) + { + /* Extract the contents of the ${ ... } expansion + according to the Posix.2 rules. */ + value = extract_dollar_brace_string (string, &sindex, quoted, 0); + if (string[sindex] == RBRACE) + sindex++; + else + goto bad_substitution; + } + else + value = (char *)NULL; + + *indexp = sindex; + + /* If this is a substring spec, process it and add the result. */ + if (want_substring) + { + temp1 = parameter_brace_substring (name, temp, value, quoted); + FREE (name); + FREE (value); + FREE (temp); + + if (temp1 == &expand_param_error) + return (&expand_wdesc_error); + else if (temp1 == &expand_param_fatal) + return (&expand_wdesc_fatal); + + ret = alloc_word_desc (); + ret->word = temp1; + if (temp1 && QUOTED_NULL (temp1) && (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES))) + ret->flags |= W_QUOTED|W_HASQUOTEDNULL; + return ret; + } + else if (want_patsub) + { + temp1 = parameter_brace_patsub (name, temp, value, quoted); + FREE (name); + FREE (value); + FREE (temp); + + if (temp1 == &expand_param_error) + return (&expand_wdesc_error); + else if (temp1 == &expand_param_fatal) + return (&expand_wdesc_fatal); + + ret = alloc_word_desc (); + ret->word = temp1; + return ret; + } + + /* Do the right thing based on which character ended the variable name. */ + switch (c) + { + default: + case '\0': + bad_substitution: + report_error (_("%s: bad substitution"), string ? string : "??"); + FREE (value); + FREE (temp); + free (name); + return &expand_wdesc_error; + + case RBRACE: + if (var_is_set == 0 && unbound_vars_is_error) + { + err_unboundvar (name); + FREE (value); + FREE (temp); + free (name); + last_command_exit_value = EXECUTION_FAILURE; + return (interactive_shell ? &expand_wdesc_error : &expand_wdesc_fatal); + } + break; + + case '#': /* ${param#[#]pattern} */ + case '%': /* ${param%[%]pattern} */ + if (value == 0 || *value == '\0' || temp == 0 || *temp == '\0') + { + FREE (value); + break; + } + temp1 = parameter_brace_remove_pattern (name, temp, value, c, quoted); + free (temp); + free (value); + temp = temp1; + break; + + case '-': + case '=': + case '?': + case '+': + if (var_is_set && var_is_null == 0) + { + /* If the operator is `+', we don't want the value of the named + variable for anything, just the value of the right hand side. */ + + if (c == '+') + { + /* XXX -- if we're double-quoted and the named variable is "$@", + we want to turn off any special handling of "$@" -- + we're not using it, so whatever is on the rhs applies. */ + if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) && quoted_dollar_atp) + *quoted_dollar_atp = 0; + if (contains_dollar_at) + *contains_dollar_at = 0; + + FREE (temp); + if (value) + { + ret = parameter_brace_expand_rhs (name, value, c, + quoted, + quoted_dollar_atp, + contains_dollar_at); + /* XXX - fix up later, esp. noting presence of + W_HASQUOTEDNULL in ret->flags */ + free (value); + } + else + temp = (char *)NULL; + } + else + { + FREE (value); + } + /* Otherwise do nothing; just use the value in TEMP. */ + } + else /* VAR not set or VAR is NULL. */ + { + FREE (temp); + temp = (char *)NULL; + if (c == '=' && var_is_special) + { + report_error (_("$%s: cannot assign in this way"), name); + free (name); + free (value); + return &expand_wdesc_error; + } + else if (c == '?') + { + parameter_brace_expand_error (name, value); + return (interactive_shell ? &expand_wdesc_error : &expand_wdesc_fatal); + } + else if (c != '+') + { + /* XXX -- if we're double-quoted and the named variable is "$@", + we want to turn off any special handling of "$@" -- + we're not using it, so whatever is on the rhs applies. */ + if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) && quoted_dollar_atp) + *quoted_dollar_atp = 0; + if (contains_dollar_at) + *contains_dollar_at = 0; + + ret = parameter_brace_expand_rhs (name, value, c, quoted, + quoted_dollar_atp, + contains_dollar_at); + /* XXX - fix up later, esp. noting presence of + W_HASQUOTEDNULL in tdesc->flags */ + } + free (value); + } + + break; + } + free (name); + + if (ret == 0) + { + ret = alloc_word_desc (); + ret->flags = tflag; + ret->word = temp; + } + return (ret); +} + +/* Expand a single ${xxx} expansion. The braces are optional. When + the braces are used, parameter_brace_expand() does the work, + possibly calling param_expand recursively. */ +static WORD_DESC * +param_expand (string, sindex, quoted, expanded_something, + contains_dollar_at, quoted_dollar_at_p, had_quoted_null_p, + pflags) + char *string; + int *sindex, quoted, *expanded_something, *contains_dollar_at; + int *quoted_dollar_at_p, *had_quoted_null_p, pflags; +{ + char *temp, *temp1, uerror[3]; + int zindex, t_index, expok; + unsigned char c; + intmax_t number; + SHELL_VAR *var; + WORD_LIST *list; + WORD_DESC *tdesc, *ret; + int tflag; + + zindex = *sindex; + c = string[++zindex]; + + temp = (char *)NULL; + ret = tdesc = (WORD_DESC *)NULL; + tflag = 0; + + /* Do simple cases first. Switch on what follows '$'. */ + switch (c) + { + /* $0 .. $9? */ + case '0': + case '1': + case '2': + case '3': + case '4': + case '5': + case '6': + case '7': + case '8': + case '9': + temp1 = dollar_vars[TODIGIT (c)]; + if (unbound_vars_is_error && temp1 == (char *)NULL) + { + uerror[0] = '$'; + uerror[1] = c; + uerror[2] = '\0'; + err_unboundvar (uerror); + last_command_exit_value = EXECUTION_FAILURE; + return (interactive_shell ? &expand_wdesc_error : &expand_wdesc_fatal); + } + if (temp1) + temp = (*temp1 && (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES))) + ? quote_string (temp1) + : quote_escapes (temp1); + else + temp = (char *)NULL; + + break; + + /* $$ -- pid of the invoking shell. */ + case '$': + temp = itos (dollar_dollar_pid); + break; + + /* $# -- number of positional parameters. */ + case '#': + temp = itos (number_of_args ()); + break; + + /* $? -- return value of the last synchronous command. */ + case '?': + temp = itos (last_command_exit_value); + break; + + /* $- -- flags supplied to the shell on invocation or by `set'. */ + case '-': + temp = which_set_flags (); + break; + + /* $! -- Pid of the last asynchronous command. */ + case '!': + /* If no asynchronous pids have been created, expand to nothing. + If `set -u' has been executed, and no async processes have + been created, this is an expansion error. */ + if (last_asynchronous_pid == NO_PID) + { + if (expanded_something) + *expanded_something = 0; + temp = (char *)NULL; + if (unbound_vars_is_error) + { + uerror[0] = '$'; + uerror[1] = c; + uerror[2] = '\0'; + err_unboundvar (uerror); + last_command_exit_value = EXECUTION_FAILURE; + return (interactive_shell ? &expand_wdesc_error : &expand_wdesc_fatal); + } + } + else + temp = itos (last_asynchronous_pid); + break; + + /* The only difference between this and $@ is when the arg is quoted. */ + case '*': /* `$*' */ + list = list_rest_of_args (); + + /* If there are no command-line arguments, this should just + disappear if there are other characters in the expansion, + even if it's quoted. */ + if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) && list == 0) + temp = (char *)NULL; + else if (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) + { + /* If we have "$*" we want to make a string of the positional + parameters, separated by the first character of $IFS, and + quote the whole string, including the separators. If IFS + is unset, the parameters are separated by ' '; if $IFS is + null, the parameters are concatenated. */ + temp = (quoted & Q_DOUBLE_QUOTES) ? string_list_dollar_star (list) : string_list (list); + temp1 = quote_string (temp); + if (*temp == 0) + tflag |= W_HASQUOTEDNULL; + free (temp); + temp = temp1; + } + else + { + /* We check whether or not we're eventually going to split $* here, + for example when IFS is empty and we are processing the rhs of + an assignment statement. In that case, we don't separate the + arguments at all. Otherwise, if the $* is not quoted it is + identical to $@ */ +#if 1 +# if defined (HANDLE_MULTIBYTE) + if (expand_no_split_dollar_star && ifs_firstc[0] == 0) +# else + if (expand_no_split_dollar_star && ifs_firstc == 0) +# endif + temp = string_list_dollar_star (list); + else + temp = string_list_dollar_at (list, quoted); +#else + temp = string_list_dollar_at (list, quoted); +#endif + if (expand_no_split_dollar_star == 0 && contains_dollar_at) + *contains_dollar_at = 1; + } + + dispose_words (list); + break; + + /* When we have "$@" what we want is "$1" "$2" "$3" ... This + means that we have to turn quoting off after we split into + the individually quoted arguments so that the final split + on the first character of $IFS is still done. */ + case '@': /* `$@' */ + list = list_rest_of_args (); + + /* We want to flag the fact that we saw this. We can't turn + off quoting entirely, because other characters in the + string might need it (consider "\"$@\""), but we need some + way to signal that the final split on the first character + of $IFS should be done, even though QUOTED is 1. */ + if (quoted_dollar_at_p && (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES))) + *quoted_dollar_at_p = 1; + if (contains_dollar_at) + *contains_dollar_at = 1; + + /* We want to separate the positional parameters with the first + character of $IFS in case $IFS is something other than a space. + We also want to make sure that splitting is done no matter what -- + according to POSIX.2, this expands to a list of the positional + parameters no matter what IFS is set to. */ + temp = string_list_dollar_at (list, quoted); + + dispose_words (list); + break; + + case LBRACE: + tdesc = parameter_brace_expand (string, &zindex, quoted, + quoted_dollar_at_p, + contains_dollar_at); + + if (tdesc == &expand_wdesc_error || tdesc == &expand_wdesc_fatal) + return (tdesc); + temp = tdesc ? tdesc->word : (char *)0; + + /* XXX */ + /* Quoted nulls should be removed if there is anything else + in the string. */ + /* Note that we saw the quoted null so we can add one back at + the end of this function if there are no other characters + in the string, discard TEMP, and go on. The exception to + this is when we have "${@}" and $1 is '', since $@ needs + special handling. */ + if (tdesc && tdesc->word && (tdesc->flags & W_HASQUOTEDNULL) && QUOTED_NULL (temp)) + { + if (had_quoted_null_p) + *had_quoted_null_p = 1; + if (*quoted_dollar_at_p == 0) + { + free (temp); + tdesc->word = temp = (char *)NULL; + } + + } + + ret = tdesc; + goto return0; + + /* Do command or arithmetic substitution. */ + case LPAREN: + /* We have to extract the contents of this paren substitution. */ + t_index = zindex + 1; + temp = extract_command_subst (string, &t_index); + zindex = t_index; + + /* For Posix.2-style `$(( ))' arithmetic substitution, + extract the expression and pass it to the evaluator. */ + if (temp && *temp == LPAREN) + { + char *temp2; + temp1 = temp + 1; + temp2 = savestring (temp1); + t_index = strlen (temp2) - 1; + + if (temp2[t_index] != RPAREN) + { + free (temp2); + goto comsub; + } + + /* Cut off ending `)' */ + temp2[t_index] = '\0'; + + if (chk_arithsub (temp2, t_index) == 0) + { + free (temp2); + goto comsub; + } + + /* Expand variables found inside the expression. */ + temp1 = expand_arith_string (temp2, Q_DOUBLE_QUOTES); + free (temp2); + +arithsub: + /* No error messages. */ + this_command_name = (char *)NULL; + number = evalexp (temp1, &expok); + free (temp); + free (temp1); + if (expok == 0) + { + if (interactive_shell == 0 && posixly_correct) + { + last_command_exit_value = EXECUTION_FAILURE; + return (&expand_wdesc_fatal); + } + else + return (&expand_wdesc_error); + } + temp = itos (number); + break; + } + +comsub: + if (pflags & PF_NOCOMSUB) + /* we need zindex+1 because string[zindex] == RPAREN */ + temp1 = substring (string, *sindex, zindex+1); + else + { + tdesc = command_substitute (temp, quoted); + temp1 = tdesc ? tdesc->word : (char *)NULL; + dispose_word_desc (tdesc); + } + FREE (temp); + temp = temp1; + break; + + /* Do POSIX.2d9-style arithmetic substitution. This will probably go + away in a future bash release. */ + case '[': + /* Extract the contents of this arithmetic substitution. */ + t_index = zindex + 1; + temp = extract_arithmetic_subst (string, &t_index); + zindex = t_index; + + /* Do initial variable expansion. */ + temp1 = expand_arith_string (temp, Q_DOUBLE_QUOTES); + + goto arithsub; + + default: + /* Find the variable in VARIABLE_LIST. */ + temp = (char *)NULL; + + for (t_index = zindex; (c = string[zindex]) && legal_variable_char (c); zindex++) + ; + temp1 = (zindex > t_index) ? substring (string, t_index, zindex) : (char *)NULL; + + /* If this isn't a variable name, then just output the `$'. */ + if (temp1 == 0 || *temp1 == '\0') + { + FREE (temp1); + temp = (char *)xmalloc (2); + temp[0] = '$'; + temp[1] = '\0'; + if (expanded_something) + *expanded_something = 0; + goto return0; + } + + /* If the variable exists, return its value cell. */ + var = find_variable (temp1); + + if (var && invisible_p (var) == 0 && var_isset (var)) + { +#if defined (ARRAY_VARS) + if (array_p (var)) + { + temp = array_reference (array_cell (var), 0); + if (temp) + temp = (*temp && (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES))) + ? quote_string (temp) + : quote_escapes (temp); + else if (unbound_vars_is_error) + goto unbound_variable; + } + else +#endif + { + temp = value_cell (var); + + temp = (*temp && (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES))) + ? quote_string (temp) + : quote_escapes (temp); + } + + free (temp1); + + goto return0; + } + + temp = (char *)NULL; + +unbound_variable: + if (unbound_vars_is_error) + err_unboundvar (temp1); + else + { + free (temp1); + goto return0; + } + + free (temp1); + last_command_exit_value = EXECUTION_FAILURE; + return ((unbound_vars_is_error && interactive_shell == 0) + ? &expand_wdesc_fatal + : &expand_wdesc_error); + } + + if (string[zindex]) + zindex++; + +return0: + *sindex = zindex; + + if (ret == 0) + { + ret = alloc_word_desc (); + ret->flags = tflag; /* XXX */ + ret->word = temp; + } + return ret; +} + +/* Make a word list which is the result of parameter and variable + expansion, command substitution, arithmetic substitution, and + quote removal of WORD. Return a pointer to a WORD_LIST which is + the result of the expansion. If WORD contains a null word, the + word list returned is also null. + + QUOTED contains flag values defined in shell.h. + + ISEXP is used to tell expand_word_internal that the word should be + treated as the result of an expansion. This has implications for + how IFS characters in the word are treated. + + CONTAINS_DOLLAR_AT and EXPANDED_SOMETHING are return values; when non-null + they point to an integer value which receives information about expansion. + CONTAINS_DOLLAR_AT gets non-zero if WORD contained "$@", else zero. + EXPANDED_SOMETHING get non-zero if WORD contained any parameter expansions, + else zero. + + This only does word splitting in the case of $@ expansion. In that + case, we split on ' '. */ + +/* Values for the local variable quoted_state. */ +#define UNQUOTED 0 +#define PARTIALLY_QUOTED 1 +#define WHOLLY_QUOTED 2 + +static WORD_LIST * +expand_word_internal (word, quoted, isexp, contains_dollar_at, expanded_something) + WORD_DESC *word; + int quoted, isexp; + int *contains_dollar_at; + int *expanded_something; +{ + WORD_LIST *list; + WORD_DESC *tword; + + /* The intermediate string that we build while expanding. */ + char *istring; + + /* The current size of the above object. */ + int istring_size; + + /* Index into ISTRING. */ + int istring_index; + + /* Temporary string storage. */ + char *temp, *temp1; + + /* The text of WORD. */ + register char *string; + + /* The size of STRING. */ + size_t string_size; + + /* The index into STRING. */ + int sindex; + + /* This gets 1 if we see a $@ while quoted. */ + int quoted_dollar_at; + + /* One of UNQUOTED, PARTIALLY_QUOTED, or WHOLLY_QUOTED, depending on + whether WORD contains no quoting characters, a partially quoted + string (e.g., "xx"ab), or is fully quoted (e.g., "xxab"). */ + int quoted_state; + + /* State flags */ + int had_quoted_null; + int has_dollar_at; + int tflag; + + int assignoff; /* If assignment, offset of `=' */ + + register unsigned char c; /* Current character. */ + int t_index; /* For calls to string_extract_xxx. */ + + char twochars[2]; + + DECLARE_MBSTATE; + + istring = (char *)xmalloc (istring_size = DEFAULT_INITIAL_ARRAY_SIZE); + istring[istring_index = 0] = '\0'; + quoted_dollar_at = had_quoted_null = has_dollar_at = 0; + quoted_state = UNQUOTED; + + string = word->word; + if (string == 0) + goto finished_with_string; + /* Don't need the string length for the SADD... and COPY_ macros unless + multibyte characters are possible. */ + string_size = (MB_CUR_MAX > 1) ? strlen (string) : 1; + + if (contains_dollar_at) + *contains_dollar_at = 0; + + assignoff = -1; + + /* Begin the expansion. */ + + for (sindex = 0; ;) + { + c = string[sindex]; + + /* Case on toplevel character. */ + switch (c) + { + case '\0': + goto finished_with_string; + + case CTLESC: + sindex++; +#if HANDLE_MULTIBYTE + if (MB_CUR_MAX > 1 && string[sindex]) + { + SADD_MBQCHAR_BODY(temp, string, sindex, string_size); + } + else +#endif + { + temp = (char *)xmalloc (3); + temp[0] = CTLESC; + temp[1] = c = string[sindex]; + temp[2] = '\0'; + } + +dollar_add_string: + if (string[sindex]) + sindex++; + +add_string: + if (temp) + { + istring = sub_append_string (temp, istring, &istring_index, &istring_size); + temp = (char *)0; + } + + break; + +#if defined (PROCESS_SUBSTITUTION) + /* Process substitution. */ + case '<': + case '>': + { + if (string[++sindex] != LPAREN || (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) || (word->flags & (W_DQUOTE|W_NOPROCSUB)) || posixly_correct) + { + sindex--; /* add_character: label increments sindex */ + goto add_character; + } + else + t_index = sindex + 1; /* skip past both '<' and LPAREN */ + + temp1 = extract_process_subst (string, (c == '<') ? "<(" : ">(", &t_index); /*))*/ + sindex = t_index; + + /* If the process substitution specification is `<()', we want to + open the pipe for writing in the child and produce output; if + it is `>()', we want to open the pipe for reading in the child + and consume input. */ + temp = temp1 ? process_substitute (temp1, (c == '>')) : (char *)0; + + FREE (temp1); + + goto dollar_add_string; + } +#endif /* PROCESS_SUBSTITUTION */ + + case '=': + /* Posix.2 section 3.6.1 says that tildes following `=' in words + which are not assignment statements are not expanded. If the + shell isn't in posix mode, though, we perform tilde expansion + on `likely candidate' unquoted assignment statements (flags + include W_ASSIGNMENT but not W_QUOTED). A likely candidate + contains an unquoted :~ or =~. Something to think about: we + now have a flag that says to perform tilde expansion on arguments + to `assignment builtins' like declare and export that look like + assignment statements. We now do tilde expansion on such words + even in POSIX mode. */ + if (word->flags & (W_ASSIGNRHS|W_NOTILDE)) + goto add_character; + /* If we're not in posix mode or forcing assignment-statement tilde + expansion, note where the `=' appears in the word and prepare to + do tilde expansion following the first `='. */ + if ((word->flags & W_ASSIGNMENT) && + (posixly_correct == 0 || (word->flags & W_TILDEEXP)) && + assignoff == -1 && sindex > 0) + assignoff = sindex; + if (sindex == assignoff && string[sindex+1] == '~') /* XXX */ + word->flags |= W_ITILDE; +#if 0 + else if ((word->flags & W_ASSIGNMENT) && + (posixly_correct == 0 || (word->flags & W_TILDEEXP)) && + string[sindex+1] == '~') + word->flags |= W_ITILDE; +#endif + goto add_character; + + case ':': + if (word->flags & W_NOTILDE) + goto add_character; + + if ((word->flags & (W_ASSIGNMENT|W_ASSIGNRHS|W_TILDEEXP)) && + string[sindex+1] == '~') + word->flags |= W_ITILDE; + goto add_character; + + case '~': + /* If the word isn't supposed to be tilde expanded, or we're not + at the start of a word or after an unquoted : or = in an + assignment statement, we don't do tilde expansion. */ + if ((word->flags & (W_NOTILDE|W_DQUOTE)) || + (sindex > 0 && ((word->flags & W_ITILDE) == 0)) || + (quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT))) + { + word->flags &= ~W_ITILDE; + goto add_character; + } + + if (word->flags & W_ASSIGNRHS) + tflag = 2; + else if (word->flags & (W_ASSIGNMENT|W_TILDEEXP)) + tflag = 1; + else + tflag = 0; + + temp = bash_tilde_find_word (string + sindex, tflag, &t_index); + + word->flags &= ~W_ITILDE; + + if (temp && *temp && t_index > 0) + { + temp1 = bash_tilde_expand (temp, tflag); + if (temp1 && *temp1 == '~' && STREQ (temp, temp1)) + { + FREE (temp); + FREE (temp1); + goto add_character; /* tilde expansion failed */ + } + free (temp); + temp = temp1; + sindex += t_index; + goto add_string; + } + else + { + FREE (temp); + goto add_character; + } + + case '$': + if (expanded_something) + *expanded_something = 1; + + has_dollar_at = 0; + tword = param_expand (string, &sindex, quoted, expanded_something, + &has_dollar_at, "ed_dollar_at, + &had_quoted_null, + (word->flags & W_NOCOMSUB) ? PF_NOCOMSUB : 0); + + if (tword == &expand_wdesc_error || tword == &expand_wdesc_fatal) + { + free (string); + free (istring); + return ((tword == &expand_wdesc_error) ? &expand_word_error + : &expand_word_fatal); + } + if (contains_dollar_at && has_dollar_at) + *contains_dollar_at = 1; + + if (tword && (tword->flags & W_HASQUOTEDNULL)) + had_quoted_null = 1; + + temp = tword->word; + dispose_word_desc (tword); + + goto add_string; + break; + + case '`': /* Backquoted command substitution. */ + { + t_index = sindex++; + + temp = string_extract (string, &sindex, "`", EX_REQMATCH); + /* The test of sindex against t_index is to allow bare instances of + ` to pass through, for backwards compatibility. */ + if (temp == &extract_string_error || temp == &extract_string_fatal) + { + if (sindex - 1 == t_index) + { + sindex = t_index; + goto add_character; + } + report_error (_("bad substitution: no closing \"`\" in %s") , string+t_index); + free (string); + free (istring); + return ((temp == &extract_string_error) ? &expand_word_error + : &expand_word_fatal); + } + + if (expanded_something) + *expanded_something = 1; + + if (word->flags & W_NOCOMSUB) + /* sindex + 1 because string[sindex] == '`' */ + temp1 = substring (string, t_index, sindex + 1); + else + { + de_backslash (temp); + tword = command_substitute (temp, quoted); + temp1 = tword ? tword->word : (char *)NULL; + dispose_word_desc (tword); + } + FREE (temp); + temp = temp1; + goto dollar_add_string; + } + + case '\\': + if (string[sindex + 1] == '\n') + { + sindex += 2; + continue; + } + + c = string[++sindex]; + + if (quoted & Q_HERE_DOCUMENT) + tflag = CBSHDOC; + else if (quoted & Q_DOUBLE_QUOTES) + tflag = CBSDQUOTE; + else + tflag = 0; + + if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) && ((sh_syntaxtab[c] & tflag) == 0)) + { + SCOPY_CHAR_I (twochars, '\\', c, string, sindex, string_size); + } + else if (c == 0) + { + c = CTLNUL; + sindex--; /* add_character: label increments sindex */ + goto add_character; + } + else + { + SCOPY_CHAR_I (twochars, CTLESC, c, string, sindex, string_size); + } + + sindex++; +add_twochars: + /* BEFORE jumping here, we need to increment sindex if appropriate */ + RESIZE_MALLOCED_BUFFER (istring, istring_index, 2, istring_size, + DEFAULT_ARRAY_SIZE); + istring[istring_index++] = twochars[0]; + istring[istring_index++] = twochars[1]; + istring[istring_index] = '\0'; + + break; + + case '"': +#if 0 + if ((quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT)) || (word->flags & W_DQUOTE)) +#else + if ((quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT))) +#endif + goto add_character; + + t_index = ++sindex; + temp = string_extract_double_quoted (string, &sindex, 0); + + /* If the quotes surrounded the entire string, then the + whole word was quoted. */ + quoted_state = (t_index == 1 && string[sindex] == '\0') + ? WHOLLY_QUOTED + : PARTIALLY_QUOTED; + + if (temp && *temp) + { + tword = alloc_word_desc (); + tword->word = temp; + + temp = (char *)NULL; + + has_dollar_at = 0; + /* Need to get W_HASQUOTEDNULL flag through this function. */ + list = expand_word_internal (tword, Q_DOUBLE_QUOTES, 0, &has_dollar_at, (int *)NULL); + + if (list == &expand_word_error || list == &expand_word_fatal) + { + free (istring); + free (string); + /* expand_word_internal has already freed temp_word->word + for us because of the way it prints error messages. */ + tword->word = (char *)NULL; + dispose_word (tword); + return list; + } + + dispose_word (tword); + + /* "$@" (a double-quoted dollar-at) expands into nothing, + not even a NULL word, when there are no positional + parameters. */ + if (list == 0 && has_dollar_at) + { + quoted_dollar_at++; + break; + } + + /* If we get "$@", we know we have expanded something, so we + need to remember it for the final split on $IFS. This is + a special case; it's the only case where a quoted string + can expand into more than one word. It's going to come back + from the above call to expand_word_internal as a list with + a single word, in which all characters are quoted and + separated by blanks. What we want to do is to turn it back + into a list for the next piece of code. */ + if (list) + dequote_list (list); + + if (list && list->word && (list->word->flags & W_HASQUOTEDNULL)) + had_quoted_null = 1; + + if (has_dollar_at) + { + quoted_dollar_at++; + if (contains_dollar_at) + *contains_dollar_at = 1; + if (expanded_something) + *expanded_something = 1; + } + } + else + { + /* What we have is "". This is a minor optimization. */ + FREE (temp); + list = (WORD_LIST *)NULL; + } + + /* The code above *might* return a list (consider the case of "$@", + where it returns "$1", "$2", etc.). We can't throw away the + rest of the list, and we have to make sure each word gets added + as quoted. We test on tresult->next: if it is non-NULL, we + quote the whole list, save it to a string with string_list, and + add that string. We don't need to quote the results of this + (and it would be wrong, since that would quote the separators + as well), so we go directly to add_string. */ + if (list) + { + if (list->next) + { + /* Testing quoted_dollar_at makes sure that "$@" is + split correctly when $IFS does not contain a space. */ + temp = quoted_dollar_at + ? string_list_dollar_at (list, Q_DOUBLE_QUOTES) + : string_list (quote_list (list)); + dispose_words (list); + goto add_string; + } + else + { + temp = savestring (list->word->word); + tflag = list->word->flags; + dispose_words (list); + + /* If the string is not a quoted null string, we want + to remove any embedded unquoted CTLNUL characters. + We do not want to turn quoted null strings back into + the empty string, though. We do this because we + want to remove any quoted nulls from expansions that + contain other characters. For example, if we have + x"$*"y or "x$*y" and there are no positional parameters, + the $* should expand into nothing. */ + /* We use the W_HASQUOTEDNULL flag to differentiate the + cases: a quoted null character as above and when + CTLNUL is contained in the (non-null) expansion + of some variable. We use the had_quoted_null flag to + pass the value through this function to its caller. */ + if ((tflag & W_HASQUOTEDNULL) && QUOTED_NULL (temp) == 0) + remove_quoted_nulls (temp); /* XXX */ + } + } + else + temp = (char *)NULL; + + /* We do not want to add quoted nulls to strings that are only + partially quoted; we can throw them away. */ + if (temp == 0 && quoted_state == PARTIALLY_QUOTED) + continue; + + add_quoted_string: + + if (temp) + { + temp1 = temp; + temp = quote_string (temp); + free (temp1); + goto add_string; + } + else + { + /* Add NULL arg. */ + c = CTLNUL; + sindex--; /* add_character: label increments sindex */ + goto add_character; + } + + /* break; */ + + case '\'': +#if 0 + if ((quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT)) || (word->flags & W_DQUOTE)) +#else + if ((quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT))) +#endif + goto add_character; + + t_index = ++sindex; + temp = string_extract_single_quoted (string, &sindex); + + /* If the entire STRING was surrounded by single quotes, + then the string is wholly quoted. */ + quoted_state = (t_index == 1 && string[sindex] == '\0') + ? WHOLLY_QUOTED + : PARTIALLY_QUOTED; + + /* If all we had was '', it is a null expansion. */ + if (*temp == '\0') + { + free (temp); + temp = (char *)NULL; + } + else + remove_quoted_escapes (temp); /* ??? */ + + /* We do not want to add quoted nulls to strings that are only + partially quoted; such nulls are discarded. */ + if (temp == 0 && (quoted_state == PARTIALLY_QUOTED)) + continue; + + /* If we have a quoted null expansion, add a quoted NULL to istring. */ + if (temp == 0) + { + c = CTLNUL; + sindex--; /* add_character: label increments sindex */ + goto add_character; + } + else + goto add_quoted_string; + + /* break; */ + + default: + /* This is the fix for " $@ " */ + if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) || (isexp == 0 && isifs (c))) + { + if (string[sindex]) /* from old goto dollar_add_string */ + sindex++; + if (c == 0) + { + c = CTLNUL; + goto add_character; + } + else + { +#if HANDLE_MULTIBYTE + if (MB_CUR_MAX > 1) + sindex--; + + if (MB_CUR_MAX > 1) + { + SADD_MBQCHAR_BODY(temp, string, sindex, string_size); + } + else +#endif + { + twochars[0] = CTLESC; + twochars[1] = c; + goto add_twochars; + } + } + } + + SADD_MBCHAR (temp, string, sindex, string_size); + + add_character: + RESIZE_MALLOCED_BUFFER (istring, istring_index, 1, istring_size, + DEFAULT_ARRAY_SIZE); + istring[istring_index++] = c; + istring[istring_index] = '\0'; + + /* Next character. */ + sindex++; + } + } + +finished_with_string: + /* OK, we're ready to return. If we have a quoted string, and + quoted_dollar_at is not set, we do no splitting at all; otherwise + we split on ' '. The routines that call this will handle what to + do if nothing has been expanded. */ + + /* Partially and wholly quoted strings which expand to the empty + string are retained as an empty arguments. Unquoted strings + which expand to the empty string are discarded. The single + exception is the case of expanding "$@" when there are no + positional parameters. In that case, we discard the expansion. */ + + /* Because of how the code that handles "" and '' in partially + quoted strings works, we need to make ISTRING into a QUOTED_NULL + if we saw quoting characters, but the expansion was empty. + "" and '' are tossed away before we get to this point when + processing partially quoted strings. This makes "" and $xxx"" + equivalent when xxx is unset. We also look to see whether we + saw a quoted null from a ${} expansion and add one back if we + need to. */ + + /* If we expand to nothing and there were no single or double quotes + in the word, we throw it away. Otherwise, we return a NULL word. + The single exception is for $@ surrounded by double quotes when + there are no positional parameters. In that case, we also throw + the word away. */ + + if (*istring == '\0') + { + if (quoted_dollar_at == 0 && (had_quoted_null || quoted_state == PARTIALLY_QUOTED)) + { + istring[0] = CTLNUL; + istring[1] = '\0'; + tword = make_bare_word (istring); + tword->flags |= W_HASQUOTEDNULL; /* XXX */ + list = make_word_list (tword, (WORD_LIST *)NULL); + if (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) + tword->flags |= W_QUOTED; + } + /* According to sh, ksh, and Posix.2, if a word expands into nothing + and a double-quoted "$@" appears anywhere in it, then the entire + word is removed. */ + else if (quoted_state == UNQUOTED || quoted_dollar_at) + list = (WORD_LIST *)NULL; +#if 0 + else + { + tword = make_bare_word (istring); + if (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) + tword->flags |= W_QUOTED; + list = make_word_list (tword, (WORD_LIST *)NULL); + } +#else + else + list = (WORD_LIST *)NULL; +#endif + } + else if (word->flags & W_NOSPLIT) + { + tword = make_bare_word (istring); + if (word->flags & W_ASSIGNMENT) + tword->flags |= W_ASSIGNMENT; /* XXX */ + if (word->flags & W_COMPASSIGN) + tword->flags |= W_COMPASSIGN; /* XXX */ + if (word->flags & W_NOGLOB) + tword->flags |= W_NOGLOB; /* XXX */ + if (word->flags & W_NOEXPAND) + tword->flags |= W_NOEXPAND; /* XXX */ + if (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) + tword->flags |= W_QUOTED; + if (had_quoted_null) + tword->flags |= W_HASQUOTEDNULL; + list = make_word_list (tword, (WORD_LIST *)NULL); + } + else + { + char *ifs_chars; + + ifs_chars = (quoted_dollar_at || has_dollar_at) ? ifs_value : (char *)NULL; + + /* If we have $@, we need to split the results no matter what. If + IFS is unset or NULL, string_list_dollar_at has separated the + positional parameters with a space, so we split on space (we have + set ifs_chars to " \t\n" above if ifs is unset). If IFS is set, + string_list_dollar_at has separated the positional parameters + with the first character of $IFS, so we split on $IFS. */ + if (has_dollar_at && ifs_chars) + list = list_string (istring, *ifs_chars ? ifs_chars : " ", 1); + else + { + tword = make_bare_word (istring); + if ((quoted & (Q_DOUBLE_QUOTES|Q_HERE_DOCUMENT)) || (quoted_state == WHOLLY_QUOTED)) + tword->flags |= W_QUOTED; + if (word->flags & W_ASSIGNMENT) + tword->flags |= W_ASSIGNMENT; + if (word->flags & W_COMPASSIGN) + tword->flags |= W_COMPASSIGN; + if (word->flags & W_NOGLOB) + tword->flags |= W_NOGLOB; + if (word->flags & W_NOEXPAND) + tword->flags |= W_NOEXPAND; + if (had_quoted_null) + tword->flags |= W_HASQUOTEDNULL; /* XXX */ + list = make_word_list (tword, (WORD_LIST *)NULL); + } + } + + free (istring); + return (list); +} + +/* **************************************************************** */ +/* */ +/* Functions for Quote Removal */ +/* */ +/* **************************************************************** */ + +/* Perform quote removal on STRING. If QUOTED > 0, assume we are obeying the + backslash quoting rules for within double quotes or a here document. */ +char * +string_quote_removal (string, quoted) + char *string; + int quoted; +{ + size_t slen; + char *r, *result_string, *temp, *send; + int sindex, tindex, dquote; + unsigned char c; + DECLARE_MBSTATE; + + /* The result can be no longer than the original string. */ + slen = strlen (string); + send = string + slen; + + r = result_string = (char *)xmalloc (slen + 1); + + for (dquote = sindex = 0; c = string[sindex];) + { + switch (c) + { + case '\\': + c = string[++sindex]; + if (((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) || dquote) && (sh_syntaxtab[c] & CBSDQUOTE) == 0) + *r++ = '\\'; + /* FALLTHROUGH */ + + default: + SCOPY_CHAR_M (r, string, send, sindex); + break; + + case '\'': + if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) || dquote) + { + *r++ = c; + sindex++; + break; + } + tindex = sindex + 1; + temp = string_extract_single_quoted (string, &tindex); + if (temp) + { + strcpy (r, temp); + r += strlen (r); + free (temp); + } + sindex = tindex; + break; + + case '"': + dquote = 1 - dquote; + sindex++; + break; + } + } + *r = '\0'; + return (result_string); +} + +#if 0 +/* UNUSED */ +/* Perform quote removal on word WORD. This allocates and returns a new + WORD_DESC *. */ +WORD_DESC * +word_quote_removal (word, quoted) + WORD_DESC *word; + int quoted; +{ + WORD_DESC *w; + char *t; + + t = string_quote_removal (word->word, quoted); + w = alloc_word_desc (); + w->word = t ? t : savestring (""); + return (w); +} + +/* Perform quote removal on all words in LIST. If QUOTED is non-zero, + the members of the list are treated as if they are surrounded by + double quotes. Return a new list, or NULL if LIST is NULL. */ +WORD_LIST * +word_list_quote_removal (list, quoted) + WORD_LIST *list; + int quoted; +{ + WORD_LIST *result, *t, *tresult, *e; + + for (t = list, result = (WORD_LIST *)NULL; t; t = t->next) + { + tresult = make_word_list (word_quote_removal (t->word, quoted), (WORD_LIST *)NULL); +#if 0 + result = (WORD_LIST *) list_append (result, tresult); +#else + if (result == 0) + result = e = tresult; + else + { + e->next = tresult; + while (e->next) + e = e->next; + } +#endif + } + return (result); +} +#endif + +/******************************************* + * * + * Functions to perform word splitting * + * * + *******************************************/ + +void +setifs (v) + SHELL_VAR *v; +{ + char *t; + unsigned char uc; + + ifs_var = v; + ifs_value = (v && value_cell (v)) ? value_cell (v) : " \t\n"; + + /* Should really merge ifs_cmap with sh_syntaxtab. XXX - doesn't yet + handle multibyte chars in IFS */ + memset (ifs_cmap, '\0', sizeof (ifs_cmap)); + for (t = ifs_value ; t && *t; t++) + { + uc = *t; + ifs_cmap[uc] = 1; + } + +#if defined (HANDLE_MULTIBYTE) + if (ifs_value == 0) + { + ifs_firstc[0] = '\0'; + ifs_firstc_len = 1; + } + else + { + size_t ifs_len; + ifs_len = strnlen (ifs_value, MB_CUR_MAX); + ifs_firstc_len = MBLEN (ifs_value, ifs_len); + if (ifs_firstc_len == 1 || ifs_firstc_len == 0 || MB_INVALIDCH (ifs_firstc_len)) + { + ifs_firstc[0] = ifs_value[0]; + ifs_firstc[1] = '\0'; + ifs_firstc_len = 1; + } + else + memcpy (ifs_firstc, ifs_value, ifs_firstc_len); + } +#else + ifs_firstc = ifs_value ? *ifs_value : 0; +#endif +} + +char * +getifs () +{ + return ifs_value; +} + +/* This splits a single word into a WORD LIST on $IFS, but only if the word + is not quoted. list_string () performs quote removal for us, even if we + don't do any splitting. */ +WORD_LIST * +word_split (w, ifs_chars) + WORD_DESC *w; + char *ifs_chars; +{ + WORD_LIST *result; + + if (w) + { + char *xifs; + + xifs = ((w->flags & W_QUOTED) || ifs_chars == 0) ? "" : ifs_chars; + result = list_string (w->word, xifs, w->flags & W_QUOTED); + } + else + result = (WORD_LIST *)NULL; + + return (result); +} + +/* Perform word splitting on LIST and return the RESULT. It is possible + to return (WORD_LIST *)NULL. */ +static WORD_LIST * +word_list_split (list) + WORD_LIST *list; +{ + WORD_LIST *result, *t, *tresult, *e; + + for (t = list, result = (WORD_LIST *)NULL; t; t = t->next) + { + tresult = word_split (t->word, ifs_value); + if (result == 0) + result = e = tresult; + else + { + e->next = tresult; + while (e->next) + e = e->next; + } + } + return (result); +} + +/************************************************** + * * + * Functions to expand an entire WORD_LIST * + * * + **************************************************/ + +/* Do any word-expansion-specific cleanup and jump to top_level */ +static void +exp_jump_to_top_level (v) + int v; +{ + /* Cleanup code goes here. */ + expand_no_split_dollar_star = 0; /* XXX */ + expanding_redir = 0; + + jump_to_top_level (v); +} + +/* Put NLIST (which is a WORD_LIST * of only one element) at the front of + ELIST, and set ELIST to the new list. */ +#define PREPEND_LIST(nlist, elist) \ + do { nlist->next = elist; elist = nlist; } while (0) + +/* Separate out any initial variable assignments from TLIST. If set -k has + been executed, remove all assignment statements from TLIST. Initial + variable assignments and other environment assignments are placed + on SUBST_ASSIGN_VARLIST. */ +static WORD_LIST * +separate_out_assignments (tlist) + WORD_LIST *tlist; +{ + register WORD_LIST *vp, *lp; + + if (!tlist) + return ((WORD_LIST *)NULL); + + if (subst_assign_varlist) + dispose_words (subst_assign_varlist); /* Clean up after previous error */ + + subst_assign_varlist = (WORD_LIST *)NULL; + vp = lp = tlist; + + /* Separate out variable assignments at the start of the command. + Loop invariant: vp->next == lp + Loop postcondition: + lp = list of words left after assignment statements skipped + tlist = original list of words + */ + while (lp && (lp->word->flags & W_ASSIGNMENT)) + { + vp = lp; + lp = lp->next; + } + + /* If lp != tlist, we have some initial assignment statements. + We make SUBST_ASSIGN_VARLIST point to the list of assignment + words and TLIST point to the remaining words. */ + if (lp != tlist) + { + subst_assign_varlist = tlist; + /* ASSERT(vp->next == lp); */ + vp->next = (WORD_LIST *)NULL; /* terminate variable list */ + tlist = lp; /* remainder of word list */ + } + + /* vp == end of variable list */ + /* tlist == remainder of original word list without variable assignments */ + if (!tlist) + /* All the words in tlist were assignment statements */ + return ((WORD_LIST *)NULL); + + /* ASSERT(tlist != NULL); */ + /* ASSERT((tlist->word->flags & W_ASSIGNMENT) == 0); */ + + /* If the -k option is in effect, we need to go through the remaining + words, separate out the assignment words, and place them on + SUBST_ASSIGN_VARLIST. */ + if (place_keywords_in_env) + { + WORD_LIST *tp; /* tp == running pointer into tlist */ + + tp = tlist; + lp = tlist->next; + + /* Loop Invariant: tp->next == lp */ + /* Loop postcondition: tlist == word list without assignment statements */ + while (lp) + { + if (lp->word->flags & W_ASSIGNMENT) + { + /* Found an assignment statement, add this word to end of + subst_assign_varlist (vp). */ + if (!subst_assign_varlist) + subst_assign_varlist = vp = lp; + else + { + vp->next = lp; + vp = lp; + } + + /* Remove the word pointed to by LP from TLIST. */ + tp->next = lp->next; + /* ASSERT(vp == lp); */ + lp->next = (WORD_LIST *)NULL; + lp = tp->next; + } + else + { + tp = lp; + lp = lp->next; + } + } + } + return (tlist); +} + +#define WEXP_VARASSIGN 0x001 +#define WEXP_BRACEEXP 0x002 +#define WEXP_TILDEEXP 0x004 +#define WEXP_PARAMEXP 0x008 +#define WEXP_PATHEXP 0x010 + +/* All of the expansions, including variable assignments at the start of + the list. */ +#define WEXP_ALL (WEXP_VARASSIGN|WEXP_BRACEEXP|WEXP_TILDEEXP|WEXP_PARAMEXP|WEXP_PATHEXP) + +/* All of the expansions except variable assignments at the start of + the list. */ +#define WEXP_NOVARS (WEXP_BRACEEXP|WEXP_TILDEEXP|WEXP_PARAMEXP|WEXP_PATHEXP) + +/* All of the `shell expansions': brace expansion, tilde expansion, parameter + expansion, command substitution, arithmetic expansion, word splitting, and + quote removal. */ +#define WEXP_SHELLEXP (WEXP_BRACEEXP|WEXP_TILDEEXP|WEXP_PARAMEXP) + +/* Take the list of words in LIST and do the various substitutions. Return + a new list of words which is the expanded list, and without things like + variable assignments. */ + +WORD_LIST * +expand_words (list) + WORD_LIST *list; +{ + return (expand_word_list_internal (list, WEXP_ALL)); +} + +/* Same as expand_words (), but doesn't hack variable or environment + variables. */ +WORD_LIST * +expand_words_no_vars (list) + WORD_LIST *list; +{ + return (expand_word_list_internal (list, WEXP_NOVARS)); +} + +WORD_LIST * +expand_words_shellexp (list) + WORD_LIST *list; +{ + return (expand_word_list_internal (list, WEXP_SHELLEXP)); +} + +static WORD_LIST * +glob_expand_word_list (tlist, eflags) + WORD_LIST *tlist; + int eflags; +{ + char **glob_array, *temp_string; + register int glob_index; + WORD_LIST *glob_list, *output_list, *disposables, *next; + WORD_DESC *tword; + + output_list = disposables = (WORD_LIST *)NULL; + glob_array = (char **)NULL; + while (tlist) + { + /* For each word, either globbing is attempted or the word is + added to orig_list. If globbing succeeds, the results are + added to orig_list and the word (tlist) is added to the list + of disposable words. If globbing fails and failed glob + expansions are left unchanged (the shell default), the + original word is added to orig_list. If globbing fails and + failed glob expansions are removed, the original word is + added to the list of disposable words. orig_list ends up + in reverse order and requires a call to REVERSE_LIST to + be set right. After all words are examined, the disposable + words are freed. */ + next = tlist->next; + + /* If the word isn't an assignment and contains an unquoted + pattern matching character, then glob it. */ + if ((tlist->word->flags & W_NOGLOB) == 0 && + unquoted_glob_pattern_p (tlist->word->word)) + { + glob_array = shell_glob_filename (tlist->word->word); + + /* Handle error cases. + I don't think we should report errors like "No such file + or directory". However, I would like to report errors + like "Read failed". */ + + if (glob_array == 0 || GLOB_FAILED (glob_array)) + { + glob_array = (char **)xmalloc (sizeof (char *)); + glob_array[0] = (char *)NULL; + } + + /* Dequote the current word in case we have to use it. */ + if (glob_array[0] == NULL) + { + temp_string = dequote_string (tlist->word->word); + free (tlist->word->word); + tlist->word->word = temp_string; + } + + /* Make the array into a word list. */ + glob_list = (WORD_LIST *)NULL; + for (glob_index = 0; glob_array[glob_index]; glob_index++) + { + tword = make_bare_word (glob_array[glob_index]); + tword->flags |= W_GLOBEXP; /* XXX */ + glob_list = make_word_list (tword, glob_list); + } + + if (glob_list) + { + output_list = (WORD_LIST *)list_append (glob_list, output_list); + PREPEND_LIST (tlist, disposables); + } + else if (fail_glob_expansion != 0) + { + report_error (_("no match: %s"), tlist->word->word); + jump_to_top_level (DISCARD); + } + else if (allow_null_glob_expansion == 0) + { + /* Failed glob expressions are left unchanged. */ + PREPEND_LIST (tlist, output_list); + } + else + { + /* Failed glob expressions are removed. */ + PREPEND_LIST (tlist, disposables); + } + } + else + { + /* Dequote the string. */ + temp_string = dequote_string (tlist->word->word); + free (tlist->word->word); + tlist->word->word = temp_string; + PREPEND_LIST (tlist, output_list); + } + + strvec_dispose (glob_array); + glob_array = (char **)NULL; + + tlist = next; + } + + if (disposables) + dispose_words (disposables); + + if (output_list) + output_list = REVERSE_LIST (output_list, WORD_LIST *); + + return (output_list); +} + +#if defined (BRACE_EXPANSION) +static WORD_LIST * +brace_expand_word_list (tlist, eflags) + WORD_LIST *tlist; + int eflags; +{ + register char **expansions; + char *temp_string; + WORD_LIST *disposables, *output_list, *next; + WORD_DESC *w; + int eindex; + + for (disposables = output_list = (WORD_LIST *)NULL; tlist; tlist = next) + { + next = tlist->next; + + /* Only do brace expansion if the word has a brace character. If + not, just add the word list element to BRACES and continue. In + the common case, at least when running shell scripts, this will + degenerate to a bunch of calls to `xstrchr', and then what is + basically a reversal of TLIST into BRACES, which is corrected + by a call to REVERSE_LIST () on BRACES when the end of TLIST + is reached. */ + if (xstrchr (tlist->word->word, LBRACE)) + { + expansions = brace_expand (tlist->word->word); + + for (eindex = 0; temp_string = expansions[eindex]; eindex++) + { + w = make_word (temp_string); + /* If brace expansion didn't change the word, preserve + the flags. We may want to preserve the flags + unconditionally someday -- XXX */ + if (STREQ (temp_string, tlist->word->word)) + w->flags = tlist->word->flags; + output_list = make_word_list (w, output_list); + free (expansions[eindex]); + } + free (expansions); + + /* Add TLIST to the list of words to be freed after brace + expansion has been performed. */ + PREPEND_LIST (tlist, disposables); + } + else + PREPEND_LIST (tlist, output_list); + } + + if (disposables) + dispose_words (disposables); + + if (output_list) + output_list = REVERSE_LIST (output_list, WORD_LIST *); + + return (output_list); +} +#endif + +static WORD_LIST * +shell_expand_word_list (tlist, eflags) + WORD_LIST *tlist; + int eflags; +{ + WORD_LIST *expanded, *orig_list, *new_list, *next, *temp_list; + int expanded_something, has_dollar_at; + char *temp_string; + + /* We do tilde expansion all the time. This is what 1003.2 says. */ + new_list = (WORD_LIST *)NULL; + for (orig_list = tlist; tlist; tlist = next) + { + temp_string = tlist->word->word; + + next = tlist->next; + +#if defined (ARRAY_VARS) + /* If this is a compound array assignment to a builtin that accepts + such assignments (e.g., `declare'), take the assignment and perform + it separately, handling the semantics of declarations inside shell + functions. This avoids the double-evaluation of such arguments, + because `declare' does some evaluation of compound assignments on + its own. */ + if ((tlist->word->flags & (W_COMPASSIGN|W_ASSIGNARG)) == (W_COMPASSIGN|W_ASSIGNARG)) + { + int t; + + t = do_word_assignment (tlist->word); + if (t == 0) + { + last_command_exit_value = EXECUTION_FAILURE; + exp_jump_to_top_level (DISCARD); + } + + /* Now transform the word as ksh93 appears to do and go on */ + t = assignment (tlist->word->word, 0); + tlist->word->word[t] = '\0'; + tlist->word->flags &= ~(W_ASSIGNMENT|W_NOSPLIT|W_COMPASSIGN|W_ASSIGNARG); + } +#endif + + expanded_something = 0; + expanded = expand_word_internal + (tlist->word, 0, 0, &has_dollar_at, &expanded_something); + + if (expanded == &expand_word_error || expanded == &expand_word_fatal) + { + /* By convention, each time this error is returned, + tlist->word->word has already been freed. */ + tlist->word->word = (char *)NULL; + + /* Dispose our copy of the original list. */ + dispose_words (orig_list); + /* Dispose the new list we're building. */ + dispose_words (new_list); + + last_command_exit_value = EXECUTION_FAILURE; + if (expanded == &expand_word_error) + exp_jump_to_top_level (DISCARD); + else + exp_jump_to_top_level (FORCE_EOF); + } + + /* Don't split words marked W_NOSPLIT. */ + if (expanded_something && (tlist->word->flags & W_NOSPLIT) == 0) + { + temp_list = word_list_split (expanded); + dispose_words (expanded); + } + else + { + /* If no parameter expansion, command substitution, process + substitution, or arithmetic substitution took place, then + do not do word splitting. We still have to remove quoted + null characters from the result. */ + word_list_remove_quoted_nulls (expanded); + temp_list = expanded; + } + + expanded = REVERSE_LIST (temp_list, WORD_LIST *); + new_list = (WORD_LIST *)list_append (expanded, new_list); + } + + if (orig_list) + dispose_words (orig_list); + + if (new_list) + new_list = REVERSE_LIST (new_list, WORD_LIST *); + + return (new_list); +} + +/* The workhorse for expand_words () and expand_words_no_vars (). + First arg is LIST, a WORD_LIST of words. + Second arg EFLAGS is a flags word controlling which expansions are + performed. + + This does all of the substitutions: brace expansion, tilde expansion, + parameter expansion, command substitution, arithmetic expansion, + process substitution, word splitting, and pathname expansion, according + to the bits set in EFLAGS. Words with the W_QUOTED or W_NOSPLIT bits + set, or for which no expansion is done, do not undergo word splitting. + Words with the W_NOGLOB bit set do not undergo pathname expansion. */ +static WORD_LIST * +expand_word_list_internal (list, eflags) + WORD_LIST *list; + int eflags; +{ + WORD_LIST *new_list, *temp_list; + int tint; + + if (list == 0) + return ((WORD_LIST *)NULL); + + garglist = new_list = copy_word_list (list); + if (eflags & WEXP_VARASSIGN) + { + garglist = new_list = separate_out_assignments (new_list); + if (new_list == 0) + { + if (subst_assign_varlist) + { + /* All the words were variable assignments, so they are placed + into the shell's environment. */ + for (temp_list = subst_assign_varlist; temp_list; temp_list = temp_list->next) + { + this_command_name = (char *)NULL; /* no arithmetic errors */ + tint = do_word_assignment (temp_list->word); + /* Variable assignment errors in non-interactive shells + running in Posix.2 mode cause the shell to exit. */ + if (tint == 0) + { + last_command_exit_value = EXECUTION_FAILURE; + if (interactive_shell == 0 && posixly_correct) + exp_jump_to_top_level (FORCE_EOF); + else + exp_jump_to_top_level (DISCARD); + } + } + dispose_words (subst_assign_varlist); + subst_assign_varlist = (WORD_LIST *)NULL; + } + return ((WORD_LIST *)NULL); + } + } + + /* Begin expanding the words that remain. The expansions take place on + things that aren't really variable assignments. */ + +#if defined (BRACE_EXPANSION) + /* Do brace expansion on this word if there are any brace characters + in the string. */ + if ((eflags & WEXP_BRACEEXP) && brace_expansion && new_list) + new_list = brace_expand_word_list (new_list, eflags); +#endif /* BRACE_EXPANSION */ + + /* Perform the `normal' shell expansions: tilde expansion, parameter and + variable substitution, command substitution, arithmetic expansion, + and word splitting. */ + new_list = shell_expand_word_list (new_list, eflags); + + /* Okay, we're almost done. Now let's just do some filename + globbing. */ + if (new_list) + { + if ((eflags & WEXP_PATHEXP) && disallow_filename_globbing == 0) + /* Glob expand the word list unless globbing has been disabled. */ + new_list = glob_expand_word_list (new_list, eflags); + else + /* Dequote the words, because we're not performing globbing. */ + new_list = dequote_list (new_list); + } + + if ((eflags & WEXP_VARASSIGN) && subst_assign_varlist) + { + sh_wassign_func_t *assign_func; + + /* If the remainder of the words expand to nothing, Posix.2 requires + that the variable and environment assignments affect the shell's + environment. */ + assign_func = new_list ? assign_in_env : do_word_assignment; + tempenv_assign_error = 0; + + for (temp_list = subst_assign_varlist; temp_list; temp_list = temp_list->next) + { + this_command_name = (char *)NULL; + tint = (*assign_func) (temp_list->word); + /* Variable assignment errors in non-interactive shells running + in Posix.2 mode cause the shell to exit. */ + if (tint == 0) + { + if (assign_func == do_word_assignment) + { + last_command_exit_value = EXECUTION_FAILURE; + if (interactive_shell == 0 && posixly_correct) + exp_jump_to_top_level (FORCE_EOF); + else + exp_jump_to_top_level (DISCARD); + } + else + tempenv_assign_error++; + } + } + + dispose_words (subst_assign_varlist); + subst_assign_varlist = (WORD_LIST *)NULL; + } + +#if 0 + tint = list_length (new_list) + 1; + RESIZE_MALLOCED_BUFFER (glob_argv_flags, 0, tint, glob_argv_flags_size, 16); + for (tint = 0, temp_list = new_list; temp_list; temp_list = temp_list->next) + glob_argv_flags[tint++] = (temp_list->word->flags & W_GLOBEXP) ? '1' : '0'; + glob_argv_flags[tint] = '\0'; +#endif + + return (new_list); +} diff --git a/subst.c~ b/subst.c~ index d5026e0b9..181722456 100644 --- a/subst.c~ +++ b/subst.c~ @@ -216,7 +216,7 @@ static SHELL_VAR *do_compound_assignment __P((char *, char *, int)); #endif static int do_assignment_internal __P((const WORD_DESC *, int)); -static char *string_extract_verbatim __P((char *, size_t, int *, char *)); +static char *string_extract_verbatim __P((char *, size_t, int *, char *, int)); static char *string_extract __P((char *, int *, char *, int)); static char *string_extract_double_quoted __P((char *, int *, int)); static inline char *string_extract_single_quoted __P((char *, int *)); @@ -254,7 +254,7 @@ static char *parameter_brace_remove_pattern __P((char *, char *, char *, int, in static char *process_substitute __P((char *, int)); -static char *read_comsub __P((int, int)); +static char *read_comsub __P((int, int, int *)); #ifdef ARRAY_VARS static arrayind_t array_length_reference __P((char *)); @@ -886,11 +886,12 @@ skip_single_quoted (string, slen, sind) /* Just like string_extract, but doesn't hack backslashes or any of that other stuff. Obeys CTLESC quoting. Used to do splitting on $IFS. */ static char * -string_extract_verbatim (string, slen, sindex, charlist) +string_extract_verbatim (string, slen, sindex, charlist, flags) char *string; size_t slen; int *sindex; char *charlist; + int flags; { register int i = *sindex; #if defined (HANDLE_MULTIBYTE) @@ -1887,7 +1888,13 @@ string_list_dollar_at (list, quoted) sep[1] = '\0'; #endif + /* XXX -- why call quote_list if ifs == 0? we can get away without doing + it now that quote_escapes quotes spaces */ +#if 0 tlist = ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) || (ifs && *ifs == 0)) +#else + tlist = (quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) +#endif ? quote_list (list) : list_quote_escapes (list); @@ -1973,7 +1980,7 @@ list_string (string, separators, quoted) { /* Don't need string length in ADVANCE_CHAR or string_extract_verbatim unless multibyte chars are possible. */ - current_word = string_extract_verbatim (string, slen, &sindex, separators); + current_word = string_extract_verbatim (string, slen, &sindex, separators, 0); if (current_word == 0) break; @@ -2096,7 +2103,7 @@ get_word_from_string (stringp, separators, endptr) /* Don't need string length in ADVANCE_CHAR or string_extract_verbatim unless multibyte chars are possible. */ slen = (MB_CUR_MAX > 1) ? strlen (s) : 1; - current_word = string_extract_verbatim (s, slen, &sindex, separators); + current_word = string_extract_verbatim (s, slen, &sindex, separators, 0); /* Set ENDPTR to the first character after the end of the word. */ if (endptr) @@ -2922,7 +2929,12 @@ expand_string (string, quoted) /* Quote escape characters in string s, but no other characters. This is used to protect CTLESC and CTLNUL in variable values from the rest of - the word expansion process after the variable is expanded. */ + the word expansion process after the variable is expanded. If IFS is + null, we quote spaces as well, just in case we split on spaces later + (in the case of unquoted $@, we will eventually attempt to split the + entire word on spaces). Corresponding code exists in dequote_escapes. + Even if we don't end up splitting on spaces, quoting spaces is not a + problem. */ char * quote_escapes (string) char *string; @@ -2930,17 +2942,19 @@ quote_escapes (string) register char *s, *t; size_t slen; char *result, *send; + int quote_spaces; DECLARE_MBSTATE; slen = strlen (string); send = string + slen; + quote_spaces = (ifs_value && *ifs_value == 0); t = result = (char *)xmalloc ((slen * 2) + 1); s = string; while (*s) { - if (*s == CTLESC || *s == CTLNUL) + if (*s == CTLESC || *s == CTLNUL || (quote_spaces && *s == ' ')) *t++ = CTLESC; COPY_CHAR_P (t, s, send); } @@ -2982,6 +2996,7 @@ dequote_escapes (string) register char *s, *t; size_t slen; char *result, *send; + int quote_spaces; DECLARE_MBSTATE; if (string == 0) @@ -2996,9 +3011,10 @@ dequote_escapes (string) if (strchr (string, CTLESC) == 0) return (strcpy (result, s)); + quote_spaces = (ifs_value && *ifs_value == 0); while (*s) { - if (*s == CTLESC && (s[1] == CTLESC || s[1] == CTLNUL)) + if (*s == CTLESC && (s[1] == CTLESC || s[1] == CTLNUL || (quote_spaces && s[1] == ' '))) { s++; if (*s == '\0') @@ -4129,12 +4145,18 @@ unlink_fifo_list () nfifo = 0; } +int +fifos_pending () +{ + return nfifo; +} + static char * make_named_pipe () { char *tname; - tname = sh_mktmpname ("sh-np", MT_USERANDOM); + tname = sh_mktmpname ("sh-np", MT_USERANDOM|MT_USETMPDIR); if (mkfifo (tname, 0600) < 0) { free (tname); @@ -4178,6 +4200,12 @@ add_fifo_list (fd) nfds++; } +int +fifos_pending () +{ + return 0; /* used for cleanup; not needed with /dev/fd */ +} + void unlink_fifo_list () { @@ -4423,21 +4451,23 @@ process_substitute (string, open_for_read_in_child) /***********************************/ static char * -read_comsub (fd, quoted) +read_comsub (fd, quoted, rflag) int fd, quoted; + int *rflag; { char *istring, buf[128], *bufp; - int istring_index, istring_size, c; + int istring_index, istring_size, c, tflag; ssize_t bufn; istring = (char *)NULL; - istring_index = istring_size = bufn = 0; + istring_index = istring_size = bufn = tflag = 0; #ifdef __CYGWIN__ setmode (fd, O_TEXT); /* we don't want CR/LF, we want Unix-style */ #endif - /* Read the output of the command through the pipe. */ + /* Read the output of the command through the pipe. This may need to be + changed to understand multibyte characters in the future. */ while (1) { if (fd < 0) @@ -4462,7 +4492,18 @@ read_comsub (fd, quoted) /* Add the character to ISTRING, possibly after resizing it. */ RESIZE_MALLOCED_BUFFER (istring, istring_index, 2, istring_size, DEFAULT_ARRAY_SIZE); - if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) || c == CTLESC || c == CTLNUL) + /* This is essentially quote_string inline */ + if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) /* || c == CTLESC || c == CTLNUL */) + istring[istring_index++] = CTLESC; + /* Escape CTLESC and CTLNUL in the output to protect those characters + from the rest of the word expansions (word splitting and globbing.) + This is essentially quote_escapes inline. */ + else if (c == CTLESC) + { + tflag |= W_HASCTLESC; + istring[istring_index++] = CTLESC; + } + else if (c == CTLNUL || (c == ' ' && (ifs_value && *ifs_value == 0))) istring[istring_index++] = CTLESC; istring[istring_index++] = c; @@ -4486,6 +4527,8 @@ read_comsub (fd, quoted) if (istring_index == 0) { FREE (istring); + if (rflag) + *rflag = tflag; return (char *)NULL; } @@ -4510,26 +4553,29 @@ read_comsub (fd, quoted) else strip_trailing (istring, istring_index - 1, 1); + if (rflag) + *rflag = tflag; return istring; } -/* Perform command substitution on STRING. This returns a string, - possibly quoted. */ -char * +/* Perform command substitution on STRING. This returns a WORD_DESC * with the + contained string possibly quoted. */ +WORD_DESC * command_substitute (string, quoted) char *string; int quoted; { pid_t pid, old_pid, old_pipeline_pgrp, old_async_pid; char *istring; - int result, fildes[2], function_value, pflags, rc; + int result, fildes[2], function_value, pflags, rc, tflag; + WORD_DESC *ret; istring = (char *)NULL; /* Don't fork () if there is no need to. In the case of no command to run, just return NULL. */ if (!string || !*string || (string[0] == '\n' && !string[1])) - return ((char *)NULL); + return ((WORD_DESC *)NULL); if (wordexp_only && read_but_dont_execute) { @@ -4569,11 +4615,7 @@ command_substitute (string, quoted) #endif /* JOB_CONTROL */ old_async_pid = last_asynchronous_pid; -#if 0 - pid = make_child ((char *)NULL, 0); -#else pid = make_child ((char *)NULL, subshell_environment&SUBSHELL_ASYNC); -#endif last_asynchronous_pid = old_async_pid; if (pid == 0) @@ -4597,7 +4639,7 @@ command_substitute (string, quoted) FREE (istring); close (fildes[0]); close (fildes[1]); - return ((char *)NULL); + return ((WORD_DESC *)NULL); } if (pid == 0) @@ -4671,6 +4713,9 @@ command_substitute (string, quoted) last_command_exit_value = rc; rc = run_exit_trap (); +#if defined (PROCESS_SUBSTITUTION) + unlink_fifo_list (); +#endif exit (rc); } else @@ -4681,7 +4726,8 @@ command_substitute (string, quoted) close (fildes[1]); - istring = read_comsub (fildes[0], quoted); + tflag = 0; + istring = read_comsub (fildes[0], quoted, &tflag); close (fildes[0]); @@ -4711,7 +4757,11 @@ command_substitute (string, quoted) give_terminal_to (pipeline_pgrp, 0); #endif /* JOB_CONTROL */ - return (istring); + ret = alloc_word_desc (); + ret->word = istring; + ret->flags = tflag; + + return ret; } } @@ -4983,7 +5033,7 @@ parameter_brace_expand_rhs (name, value, c, quoted, qdollaratp, hasdollarat) /* If the entire expression is between double quotes, we want to treat the value as a double-quoted string, with the exception that we strip - embedded unescaped double quotes. */ + embedded unescaped double quotes (for sh backwards compatibility). */ if ((quoted & (Q_HERE_DOCUMENT|Q_DOUBLE_QUOTES)) && *value) { hasdol = 0; @@ -5810,12 +5860,16 @@ parameter_brace_patsub (varname, value, patsub, quoted) #if defined (ARRAY_VARS) case VT_ARRAYVAR: temp = array_patsub (array_cell (v), p, rep, mflags); +#if 0 + /* Don't need to do this anymore; array_patsub calls array_quote_escapes + as appropriate before adding the space separators. */ if (temp && (mflags & MATCH_QUOTED) == 0) { tt = quote_escapes (temp); free (temp); temp = tt; } +#endif break; #endif } @@ -6578,7 +6632,11 @@ comsub: /* we need zindex+1 because string[zindex] == RPAREN */ temp1 = substring (string, *sindex, zindex+1); else - temp1 = command_substitute (temp, quoted); + { + tdesc = command_substitute (temp, quoted); + temp1 = tdesc ? tdesc->word : (char *)NULL; + dispose_word_desc (tdesc); + } FREE (temp); temp = temp1; break; @@ -6986,7 +7044,9 @@ add_string: else { de_backslash (temp); - temp1 = command_substitute (temp, quoted); + tword = command_substitute (temp, quoted); + temp1 = tword ? tword->word : (char *)NULL; + dispose_word_desc (tword); } FREE (temp); temp = temp1; @@ -7512,11 +7572,7 @@ setifs (v) unsigned char uc; ifs_var = v; -#if 0 - ifs_value = v ? value_cell (v) : " \t\n"; -#else ifs_value = (v && value_cell (v)) ? value_cell (v) : " \t\n"; -#endif /* Should really merge ifs_cmap with sh_syntaxtab. XXX - doesn't yet handle multibyte chars in IFS */ diff --git a/subst.h b/subst.h index 9bc6e2be0..0af502403 100644 --- a/subst.h +++ b/subst.h @@ -219,9 +219,10 @@ extern WORD_LIST *expand_words_no_vars __P((WORD_LIST *)); command substitution, arithmetic expansion, and word splitting. */ extern WORD_LIST *expand_words_shellexp __P((WORD_LIST *)); -extern char *command_substitute __P((char *, int)); +extern WORD_DESC *command_substitute __P((char *, int)); extern char *pat_subst __P((char *, char *, char *, int)); +extern int fifos_pending __P((void)); extern void unlink_fifo_list __P((void)); extern WORD_LIST *list_string_with_quotes __P((char *)); diff --git a/support/texi2html b/support/texi2html index bdb3bee33..0c608e396 100755 --- a/support/texi2html +++ b/support/texi2html @@ -3564,7 +3564,7 @@ INPUT_LINE: while ($_ = &next_line) { $name = &normalise_node($name); $level = $sec2level{$tag}; # check for index - $first_index_chapter = $name + $first_index_chapter = $node if ($level == 1 && !$first_index_chapter && $name =~ /index/i); if ($in_top && /heading/){ diff --git a/support/texi2html.debug b/support/texi2html.debug new file mode 100755 index 000000000..dbe15cd2d --- /dev/null +++ b/support/texi2html.debug @@ -0,0 +1,5439 @@ +#! /usr/bin/perl +'di '; +'ig 00 '; +#+############################################################################## +# +# texi2html: Program to transform Texinfo documents to HTML +# +# Copyright (C) 1999, 2000 Free Software Foundation, Inc. +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 2 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program; if not, write to the Free Software +# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA +# +#-############################################################################## + +# This requires perl version 5 or higher +require 5.0; + +#++############################################################################## +# +# NOTE FOR DEBUGGING THIS SCRIPT: +# You can run 'perl texi2html.pl' directly, provided you have +# the environment variable T2H_HOME set to the directory containing +# the texi2html.init file +# +#--############################################################################## + +# CVS version: +# $Id: texi2html.pl,v 1.55 2000/07/27 14:39:41 obachman Exp $ + +# Homepage: +$T2H_HOMEPAGE = < (original author) + Karl Berry + Olaf Bachmann + and many others. +Maintained by: Olaf Bachmann +Send bugs and suggestions to +EOT + +# Version: set in configure.in +$THISVERSION = '1.64'; +$THISPROG = "texi2html $THISVERSION"; # program name and version + +# The man page for this program is included at the end of this file and can be +# viewed using the command 'nroff -man texi2html'. + +# Identity: + +$T2H_TODAY = &pretty_date; # like "20 September 1993" +# the eval prevents this from breaking on system which do not have +# a proper getpwuid implemented +eval { ($T2H_USER = (getpwuid ($<))[6]) =~ s/,.*//;}; # Who am i + +#+++############################################################################ +# # +# Initialization # +# Pasted content of File $(srcdir)/texi2html.init: Default initializations # +# # +#---############################################################################ + +# leave this within comments, and keep the require statement +# This way, you can directly run texi2html.pl, if $ENV{T2H_HOME}/texi2html.init +# exists. + +# +# -*-perl-*- +###################################################################### +# File: texi2html.init +# +# Sets default values for command-line arguments and for various customizable +# procedures +# +# A copy of this file is pasted into the beginning of texi2html by +# 'make texi2html' +# +# Copy this file and make changes to it, if you like. +# Afterwards, either, load it with command-line option -init_file +# +# $Id: texi2html.init,v 1.34 2000/07/27 14:09:02 obachman Exp $ + +###################################################################### +# stuff which can also be set by command-line options +# +# +# Note: values set here, overwrite values set by the command-line +# options before -init_file and might still be overwritten by +# command-line arguments following the -init_file option +# + +# T2H_OPTIONS is a hash whose keys are the (long) names of valid +# command-line options and whose values are a hash with the following keys: +# type ==> one of !|=i|:i|=s|:s (see GetOpt::Long for more info) +# linkage ==> ref to scalar, array, or subroutine (see GetOpt::Long for more info) +# verbose ==> short description of option (displayed by -h) +# noHelp ==> if 1 -> for "not so important options": only print description on -h 1 +# 2 -> for obsolete options: only print description on -h 2 + +$T2H_DEBUG = 0; +$T2H_OPTIONS -> {debug} = +{ + type => '=i', + linkage => \$main::T2H_DEBUG, + verbose => 'output HTML with debuging information', +}; + +$T2H_DOCTYPE = ''; +$T2H_OPTIONS -> {doctype} = +{ + type => '=s', + linkage => \$main::T2H_DOCTYPE, + verbose => 'document type which is output in header of HTML files', + noHelp => 1 +}; + +$T2H_CHECK = 0; +$T2H_OPTIONS -> {check} = +{ + type => '!', + linkage => \$main::T2H_CHECK, + verbose => 'if set, only check files and output all things that may be Texinfo commands', + noHelp => 1 +}; + +# -expand +# if set to "tex" (or, "info") expand @iftex and @tex (or, @ifinfo) sections +# else, neither expand @iftex, @tex, nor @ifinfo sections +$T2H_EXPAND = "info"; +$T2H_OPTIONS -> {expand} = +{ + type => '=s', + linkage => \$T2H_EXPAND, + verbose => 'Expand info|tex|none section of texinfo source', +}; + +# - glossary +#if set, uses section named `Footnotes' for glossary +$T2H_USE_GLOSSARY = 0; +T2H_OPTIONS -> {glossary} = +{ + type => '!', + linkage => \$T2H_USE_GLOSSARY, + verbose => "if set, uses section named `Footnotes' for glossary", + noHelp => 1, +}; + + +# -invisible +# $T2H_INVISIBLE_MARK is the text used to create invisible destination +# anchors for index links (you can for instance use the invisible.xbm +# file shipped with this program). This is a workaround for a known +# bug of many WWW browsers, including netscape. +# For me, it works fine without it -- on the contrary: if there, it +# inserts space between headers and start of text (obachman 3/99) +$T2H_INVISIBLE_MARK = ''; +# $T2H_INVISIBLE_MARK = ' '; +$T2H_OPTIONS -> {invisible} = +{ + type => '=s', + linkage => \$T2H_INVISIBLE_MARK, + verbose => 'use text in invisble anchot', + noHelp => 1, +}; + +# -iso +# if set, ISO8879 characters are used for special symbols (like copyright, etc) +$T2H_USE_ISO = 0; +$T2H_OPTIONS -> {iso} = +{ + type => 'iso', + linkage => \$T2H_USE_ISO, + verbose => 'if set, ISO8879 characters are used for special symbols (like copyright, etc)', + noHelp => 1, +}; + +# -I +# list directories where @include files are searched for (besides the +# directory of the doc file) additional '-I' args add to this list +@T2H_INCLUDE_DIRS = ("."); +$T2H_OPTIONS -> {I} = +{ + type => '=s', + linkage => \@T2H_INCLUDE_DIRS, + verbose => 'append $s to the @include search path', +}; + +# -top_file +# uses file of this name for top-level file +# extension is manipulated appropriately, if necessary. +# If empty, .html is used +# Typically, you would set this to "index.html". +$T2H_TOP_FILE = ''; +$T2H_OPTIONS -> {top_file} = +{ + type => '=s', + linkage => \$T2H_TOP_FILE, + verbose => 'use $s as top file, instead of .html', +}; + + +# -toc_file +# uses file of this name for table of contents file +# extension is manipulated appropriately, if necessary. +# If empty, _toc.html is used +$T2H_TOC_FILE = ''; +$T2H_OPTIONS -> {toc_file} = +{ + type => '=s', + linkage => \$T2H_TOC_FILE, + verbose => 'use $s as ToC file, instead of _toc.html', +}; + +# -frames +# if set, output two additional files which use HTML 4.0 "frames". +$T2H_FRAMES = 0; +$T2H_OPTIONS -> {frames} = +{ + type => '!', + linkage => \$T2H_FRAMES, + verbose => 'output files which use HTML 4.0 frames (experimental)', + noHelp => 1, +}; + + +# -menu | -nomenu +# if set, show the Texinfo menus +$T2H_SHOW_MENU = 1; +$T2H_OPTIONS -> {menu} = +{ + type => '!', + linkage => \$T2H_SHOW_MENU, + verbose => 'ouput Texinfo menus', +}; + +# -number | -nonumber +# if set, number sections and show section names and numbers in references +# and menus +$T2H_NUMBER_SECTIONS = 1; +$T2H_OPTIONS -> {number} = +{ + type => '!', + linkage => \$T2H_NUMBER_SECTIONS, + verbose => 'use numbered sections' +}; + +# if set, and T2H_NUMBER_SECTIONS is set, then use node names in menu +# entries, instead of section names +$T2H_NODE_NAME_IN_MENU = 0; + +# if set and menu entry equals menu descr, then do not print menu descr. +# Likewise, if node name equals entry name, do not print entry name. +$T2H_AVOID_MENU_REDUNDANCY = 1; + +# -split section|chapter|none +# if set to 'section' (resp. 'chapter') create one html file per (sub)section +# (resp. chapter) and separate pages for Top, ToC, Overview, Index, +# Glossary, About. +# otherwise, create monolithic html file which contains whole document +#$T2H_SPLIT = 'section'; +$T2H_SPLIT = ''; +$T2H_OPTIONS -> {split} = +{ + type => '=s', + linkage => \$T2H_SPLIT, + verbose => 'split document on section|chapter else no splitting', +}; + +# -section_navigation|-no-section_navigation +# if set, then navigation panels are printed at the beginning of each section +# and, possibly at the end (depending on whether or not there were more than +# $T2H_WORDS_IN_PAGE words on page +# This is most useful if you do not want to have section navigation +# on -split chapter +$T2H_SECTION_NAVIGATION = 1; +$T2H_OPTIONS -> {sec_nav} = +{ + type => '!', + linkage => \$T2H_SECTION_NAVIGATION, + verbose => 'output navigation panels for each section', +}; + +# -subdir +# if set put result files in this directory +# if not set result files are put into current directory +#$T2H_SUBDIR = 'html'; +$T2H_SUBDIR = ''; +$T2H_OPTIONS -> {subdir} = +{ + type => '=s', + linkage => \$T2H_SUBDIR, + verbose => 'put HTML files in directory $s, instead of $cwd', +}; + +# -short_extn +# If this is set all HTML file will have extension ".htm" instead of +# ".html". This is helpful when shipping the document to PC systems. +$T2H_SHORTEXTN = 0; +$T2H_OPTIONS -> {short_ext} = +{ + type => '!', + linkage => \$T2H_SHORTEXTN, + verbose => 'use "htm" extension for output HTML files', +}; + + +# -prefix +# Set the output file prefix, prepended to all .html, .gif and .pl files. +# By default, this is the basename of the document +$T2H_PREFIX = ''; +$T2H_OPTIONS -> {prefix} = +{ + type => '=s', + linkage => \$T2H_PREFIX, + verbose => 'use as prefix for output files, instead of ', +}; + +# -o filename +# If set, generate monolithic document output html into $filename +$T2H_OUT = ''; +$T2H_OPTIONS -> {out_file} = +{ + type => '=s', + linkage => sub {$main::T2H_OUT = @_[1]; $T2H_SPLIT = '';}, + verbose => 'if set, all HTML output goes into file $s', +}; + +# -short_ref +#if set cross-references are given without section numbers +$T2H_SHORT_REF = ''; +$T2H_OPTIONS -> {short_ref} = +{ + type => '!', + linkage => \$T2H_SHORT_REF, + verbose => 'if set, references are without section numbers', +}; + +# -idx_sum +# if value is set, then for each @prinindex $what +# $docu_name_$what.idx is created which contains lines of the form +# $key\t$ref sorted alphabetically (case matters) +$T2H_IDX_SUMMARY = 0; +$T2H_OPTIONS -> {idx_sum} = +{ + type => '!', + linkage => \$T2H_IDX_SUMMARY, + verbose => 'if set, also output index summary', + noHelp => 1, +}; + +# -verbose +# if set, chatter about what we are doing +$T2H_VERBOSE = ''; +$T2H_OPTIONS -> {Verbose} = +{ + type => '!', + linkage => \$T2H_VERBOSE, + verbose => 'print progress info to stdout', +}; + +# -lang +# For page titles use $T2H_WORDS->{$T2H_LANG}->{...} as title. +# To add a new language, supply list of titles (see $T2H_WORDS below). +# and use ISO 639 language codes (see e.g. perl module Locale-Codes-1.02 +# for definitions) +# Default's to 'en' if not set or no @documentlanguage is specified +$T2H_LANG = ''; +$T2H_OPTIONS -> {lang} = +{ + type => '=s', + linkage => sub {SetDocumentLanguage($_[1])}, + verbose => 'use $s as document language (ISO 639 encoding)', +}; + +# -l2h +# if set, uses latex2html for generation of math content +$T2H_L2H = ''; +$T2H_OPTIONS -> {l2h} = +{ + type => '!', + linkage => \$T2H_L2H, + verbose => 'if set, uses latex2html for @math and @tex', +}; + +###################### +# The following options are only relevant if $T2H_L2H is set +# +# -l2h_l2h +# name/location of latex2html progam +$T2H_L2H_L2H = "latex2html"; +$T2H_OPTIONS -> {l2h_l2h} = +{ + type => '=s', + linkage => \$T2H_L2H_L2H, + verbose => 'program to use for latex2html translation', + noHelp => 1, +}; + +# -l2h_skip +# if set, skips actual call to latex2html tries to reuse previously generated +# content, instead +$T2H_L2H_SKIP = ''; +$T2H_OPTIONS -> {l2h_skip} = +{ + type => '!', + linkage => \$T2H_L2H_SKIP, + verbose => 'if set, tries to reuse previously latex2html output', + noHelp => 1, +}; + +# -l2h_tmp +# if set, l2h uses this directory for temporarary files. The path +# leading to this directory may not contain a dot (i.e., a "."), +# otherwise, l2h will fail +$T2H_L2H_TMP = ''; +$T2H_OPTIONS -> {l2h_tmp} = +{ + type => '=s', + linkage => \$T2H_L2H_TMP, + verbose => 'if set, uses $s as temporary latex2html directory', + noHelp => 1, +}; + +# if set, cleans intermediate files (they all have the prefix $doc_l2h_) +# of l2h +$T2H_L2H_CLEAN = 1; +$T2H_OPTIONS -> {l2h_clean} = +{ + type => '!', + linkage => \$T2H_L2H_CLEAN, + verbose => 'if set, do not keep intermediate latex2html files for later reuse', + noHelp => 1, +}; + +$T2H_OPTIONS -> {D} = +{ + type => '=s', + linkage => sub {$main::value{@_[1]} = 1;}, + verbose => 'equivalent to Texinfo "@set $s 1"', + noHelp => 1, +}; + +$T2H_OPTIONS -> {init_file} = +{ + type => '=s', + linkage => \&LoadInitFile, + verbose => 'load init file $s' +}; + + +############################################################################## +# +# The following can only be set in the init file +# +############################################################################## + +# if set, center @image by default +# otherwise, do not center by default +$T2H_CENTER_IMAGE = 1; + +# used as identation for block enclosing command @example, etc +# If not empty, must be enclosed in     		  
    +EOT + } + &$T2H_print_navigation($fh, $T2H_VERTICAL_HEAD_NAVIGATION); + if ($T2H_VERTICAL_HEAD_NAVIGATION) + { + print $fh < + +EOT + } + elsif ($T2H_SPLIT eq 'section') + { + print $fh "
    \n"; + } +} + +# Specifies the minimum page length required before a navigation panel +# is placed at the bottom of a page (the default is that of latex2html) +# T2H_THIS_WORDS_IN_PAGE holds number of words of current page +$T2H_WORDS_IN_PAGE = 300; +sub T2H_DEFAULT_print_foot_navigation +{ + my $fh = shift; + my $nwords = shift; + if ($T2H_VERTICAL_HEAD_NAVIGATION) + { + print $fh < +
    +EOT + } + print $fh "
    \n"; + &$T2H_print_navigation($fh) if ($nwords >= $T2H_WORDS_IN_PAGE) +} + +###################################################################### +# navigation panel +# +# specify in this array which "buttons" should appear in which order +# in the navigation panel for sections; use ' ' for empty buttons (space) +@T2H_SECTION_BUTTONS = + ( + 'Back', 'Forward', ' ', 'FastBack', 'Up', 'FastForward', + ' ', ' ', ' ', ' ', + 'Top', 'Contents', 'Index', 'About', + ); + +# buttons for misc stuff +@T2H_MISC_BUTTONS = ('Top', 'Contents', 'Index', 'About'); + +# insert here name of icon images for buttons +# Icons are used, if $T2H_ICONS and resp. value are set +%T2H_ACTIVE_ICONS = + ( + 'Top', '', + 'Contents', '', + 'Overview', '', + 'Index', '', + 'Back', '', + 'FastBack', '', + 'Prev', '', + 'Up', '', + 'Next', '', + 'Forward', '', + 'FastForward', '', + 'About' , '', + 'First', '', + 'Last', '', + ' ', '' + ); + +# insert here name of icon images for these, if button is inactive +%T2H_PASSIVE_ICONS = + ( + 'Top', '', + 'Contents', '', + 'Overview', '', + 'Index', '', + 'Back', '', + 'FastBack', '', + 'Prev', '', + 'Up', '', + 'Next', '', + 'Forward', '', + 'FastForward', '', + 'About', '', + 'First', '', + 'Last', '', + ); + +# how to create IMG tag +sub T2H_DEFAULT_button_icon_img +{ + my $button = shift; + my $icon = shift; + my $name = shift; + return qq{$button: $name}; +} + +# Names of text as alternative for icons +%T2H_NAVIGATION_TEXT = + ( + 'Top', 'Top', + 'Contents', 'Contents', + 'Overview', 'Overview', + 'Index', 'Index', + ' ', '   ', + 'Back', ' < ', + 'FastBack', ' << ', + 'Prev', 'Prev', + 'Up', ' Up ', + 'Next', 'Next', + 'Forward', ' > ', + 'FastForward', ' >> ', + 'About', ' ? ', + 'First', ' |< ', + 'Last', ' >| ' + ); + +sub T2H_DEFAULT_print_navigation +{ + my $fh = shift; + my $vertical = shift; + my $spacing = 1; + print $fh "\n"; + + print $fh "" unless $vertical; + for $button (@$T2H_BUTTONS) + { + print $fh qq{\n} if $vertical; + print $fh qq{\n"; + print $fh "\n" if $vertical; + } + print $fh "" unless $vertical; + print $fh "
    }; + + if (ref($button) eq 'CODE') + { + &$button($fh, $vertical); + } + elsif ($button eq ' ') + { # handle space button + print $fh + $T2H_ICONS && $T2H_ACTIVE_ICONS{' '} ? + &$T2H_button_icon_img($button, $T2H_ACTIVE_ICONS{' '}) : + $T2H_NAVIGATION_TEXT{' '}; + next; + } + elsif ($T2H_HREF{$button}) + { # button is active + print $fh + $T2H_ICONS && $T2H_ACTIVE_ICONS{$button} ? # use icon ? + t2h_anchor('', $T2H_HREF{$button}, # yes + &$T2H_button_icon_img($button, + $T2H_ACTIVE_ICONS{$button}, + $T2H_NAME{$button})) + : # use text + "[" . + t2h_anchor('', $T2H_HREF{$button}, $T2H_NAVIGATION_TEXT{$button}) . + "]"; + } + else + { # button is passive + print $fh + $T2H_ICONS && $T2H_PASSIVE_ICONS{$button} ? + &$T2H_button_icon_img($button, + $T2H_PASSIVE_ICONS{$button}, + $T2H_NAME{$button}) : + + "[" . $T2H_NAVIGATION_TEXT{$button} . "]"; + } + print $fh "
    \n"; +} + +###################################################################### +# Frames: this is from "Richard Y. Kim" +# Should be improved to be more conforming to other _print* functions + +sub T2H_DEFAULT_print_frame +{ + my $fh = shift; + print $fh < +$T2H_THISDOC{title} + + + + + +EOT +} + +sub T2H_DEFAULT_print_toc_frame +{ + my $fh = shift; + &$T2H_print_page_head($fh); + print $fh <Content +EOT + print $fh map {s/HREF=/target=\"main\" HREF=/; $_;} @stoc_lines; + print $fh "\n"; +} + +###################################################################### +# About page +# + +# T2H_PRE_ABOUT might be a function +$T2H_PRE_ABOUT = <texi2html +

    +EOT +$T2H_AFTER_ABOUT = ''; + +sub T2H_DEFAULT_about_body +{ + my $about; + if (ref($T2H_PRE_ABOUT) eq 'CODE') + { + $about = &$T2H_PRE_ABOUT(); + } + else + { + $about = $T2H_PRE_ABOUT; + } + $about .= <

    + + + + + + + +EOT + + for $button (@T2H_SECTION_BUTTONS) + { + next if $button eq ' ' || ref($button) eq 'CODE'; + $about .= < + + + + +EOT + } + + $about .= < +

    +where the Example assumes that the current position +is at Subsubsection One-Two-Three of a document of +the following structure: +
      +
    • 1. Section One
      • +
        +
      • 1.1 Subsection One-One
        • +
          +
        • ...
          • +
        +
      • 1.2 Subsection One-Two
        • +
          +
        • 1.2.1 Subsubsection One-Two-One +
        • 1.2.2 Subsubsection One-Two-Two +
        • 1.2.3 Subsubsection One-Two-Three     +<== Current Position +
        • 1.2.4 Subsubsection One-Two-Four +
        +
      • 1.3 Subsection One-Three
        • +
          +
        • ...
          • +
        +
      • 1.4 Subsection One-Four
        • +
      +
    +$T2H_AFTER_ABOUT +EOT + return $about; +} + + +%T2H_BUTTONS_GOTO = + ( + 'Top', 'cover (top) of document', + 'Contents', 'table of contents', + 'Overview', 'short table of contents', + 'Index', 'concept index', + 'Back', 'previous section in reading order', + 'FastBack', 'previous or up-and-previous section ', + 'Prev', 'previous section same level', + 'Up', 'up section', + 'Next', 'next section same level', + 'Forward', 'next section in reading order', + 'FastForward', 'next or up-and-next section', + 'About' , 'this page', + 'First', 'first section in reading order', + 'Last', 'last section in reading order', + ); + +%T2H_BUTTONS_EXAMPLE = +( + 'Top', '   ', + 'Contents', '   ', + 'Overview', '   ', + 'Index', '   ', + 'Back', '1.2.2', + 'FastBack', '1.1', + 'Prev', '1.2.2', + 'Up', '1.2', + 'Next', '1.2.4', + 'Forward', '1.2.4', + 'FastForward', '1.3', + 'About', '   ', + 'First', '1.', + 'Last', '1.2.4', +); + + +###################################################################### +# from here on, its l2h init stuff +# + +## initialization for latex2html as for Singular manual generation +## obachman 3/99 + +# +# Options controlling Titles, File-Names, Tracing and Sectioning +# +$TITLE = ''; + +$SHORTEXTN = 0; + +$LONG_TITLES = 0; + +$DESTDIR = ''; # should be overwritten by cmd-line argument + +$NO_SUBDIR = 0;# should be overwritten by cmd-line argument + +$PREFIX = ''; # should be overwritten by cmd-line argument + +$AUTO_PREFIX = 0; # this is needed, so that prefix settings are used + +$AUTO_LINK = 0; + +$SPLIT = 0; + +$MAX_LINK_DEPTH = 0; + +$TMP = ''; # should be overwritten by cmd-line argument + +$DEBUG = 0; + +$VERBOSE = 1; + +# +# Options controlling Extensions and Special Features +# +$HTML_VERSION = "3.2"; + +$TEXDEFS = 1; # we absolutely need that + +$EXTERNAL_FILE = ''; + +$SCALABLE_FONTS = 1; + +$NO_SIMPLE_MATH = 1; + +$LOCAL_ICONS = 1; + +$SHORT_INDEX = 0; + +$NO_FOOTNODE = 1; + +$ADDRESS = ''; + +$INFO = ''; + +# +# Switches controlling Image Generation +# +$ASCII_MODE = 0; + +$NOLATEX = 0; + +$EXTERNAL_IMAGES = 0; + +$PS_IMAGES = 0; + +$NO_IMAGES = 0; + +$IMAGES_ONLY = 0; + +$REUSE = 2; + +$ANTI_ALIAS = 1; + +$ANTI_ALIAS_TEXT = 1; + +# +#Switches controlling Navigation Panels +# +$NO_NAVIGATION = 1; +$ADDRESS = ''; +$INFO = 0; # 0 = do not make a "About this document..." section + +# +#Switches for Linking to other documents +# +# actuall -- we don't care + +$MAX_SPLIT_DEPTH = 0; # Stop making separate files at this depth + +$MAX_LINK_DEPTH = 0; # Stop showing child nodes at this depth + +$NOLATEX = 0; # 1 = do not pass unknown environments to Latex + +$EXTERNAL_IMAGES = 0; # 1 = leave the images outside the document + +$ASCII_MODE = 0; # 1 = do not use any icons or internal images + +# 1 = use links to external postscript images rather than inlined bitmap +# images. +$PS_IMAGES = 0; +$SHOW_SECTION_NUMBERS = 0; + +### Other global variables ############################################### +$CHILDLINE = ""; + +# This is the line width measured in pixels and it is used to right justify +# equations and equation arrays; +$LINE_WIDTH = 500; + +# Used in conjunction with AUTO_NAVIGATION +$WORDS_IN_PAGE = 300; + +# Affects ONLY the way accents are processed +$default_language = 'english'; + +# The value of this variable determines how many words to use in each +# title that is added to the navigation panel (see below) +# +$WORDS_IN_NAVIGATION_PANEL_TITLES = 0; + +# This number will determine the size of the equations, special characters, +# and anything which will be converted into an inlined image +# *except* "image generating environments" such as "figure", "table" +# or "minipage". +# Effective values are those greater than 0. +# Sensible values are between 0.1 - 4. +$MATH_SCALE_FACTOR = 1.5; + +# This number will determine the size of +# image generating environments such as "figure", "table" or "minipage". +# Effective values are those greater than 0. +# Sensible values are between 0.1 - 4. +$FIGURE_SCALE_FACTOR = 1.6; + + +# If both of the following two variables are set then the "Up" button +# of the navigation panel in the first node/page of a converted document +# will point to $EXTERNAL_UP_LINK. $EXTERNAL_UP_TITLE should be set +# to some text which describes this external link. +$EXTERNAL_UP_LINK = ""; +$EXTERNAL_UP_TITLE = ""; + +# If this is set then the resulting HTML will look marginally better if viewed +# with Netscape. +$NETSCAPE_HTML = 1; + +# Valid paper sizes are "letter", "legal", "a4","a3","a2" and "a0" +# Paper sizes has no effect other than in the time it takes to create inlined +# images and in whether large images can be created at all ie +# - larger paper sizes *MAY* help with large image problems +# - smaller paper sizes are quicker to handle +$PAPERSIZE = "a4"; + +# Replace "english" with another language in order to tell LaTeX2HTML that you +# want some generated section titles (eg "Table of Contents" or "References") +# to appear in a different language. Currently only "english" and "french" +# is supported but it is very easy to add your own. See the example in the +# file "latex2html.config" +$TITLES_LANGUAGE = "english"; + +1; # This must be the last non-comment line + +# End File texi2html.init +###################################################################### + + +require "$ENV{T2H_HOME}/texi2html.init" + if ($0 =~ /\.pl$/ && + -e "$ENV{T2H_HOME}/texi2html.init" && -r "$ENV{T2H_HOME}/texi2html.init"); + +#+++############################################################################ +# # +# Initialization # +# Pasted content of File $(srcdir)/MySimple.pm: Command-line processing # +# # +#---############################################################################ + +# leave this within comments, and keep the require statement +# This way, you can directly run texi2html.pl, if $ENV{T2H_HOME}/texi2html.init +# exists. + +# +package Getopt::MySimple; + +# Name: +# Getopt::MySimple. +# +# Documentation: +# POD-style (incomplete) documentation is in file MySimple.pod +# +# Tabs: +# 4 spaces || die. +# +# Author: +# Ron Savage rpsavage@ozemail.com.au. +# 1.00 19-Aug-97 Initial version. +# 1.10 13-Oct-97 Add arrays of switches (eg '=s@'). +# 1.20 3-Dec-97 Add 'Help' on a per-switch basis. +# 1.30 11-Dec-97 Change 'Help' to 'verbose'. Make all hash keys lowercase. +# 1.40 10-Nov-98 Change width of help report. Restructure tests. +# 1-Jul-00 Modifications for Texi2html + +# -------------------------------------------------------------------------- +# Locally modified by obachman (Display type instead of env, order by cmp) +# $Id: MySimple.pm,v 1.1 2000/07/03 08:44:13 obachman Exp $ + +# use strict; +# no strict 'refs'; + +use vars qw(@EXPORT @EXPORT_OK @ISA); +use vars qw($fieldWidth $opt $VERSION); + +use Exporter(); +use Getopt::Long; + +@ISA = qw(Exporter); +@EXPORT = qw(); +@EXPORT_OK = qw($opt); # An alias for $self -> {'opt'}. + +# -------------------------------------------------------------------------- + +$fieldWidth = 20; +$VERSION = '1.41'; + +# -------------------------------------------------------------------------- + +sub byOrder +{ + my($self) = @_; + + return uc($a) cmp (uc($b)); +} + +# -------------------------------------------------------------------------- + +sub dumpOptions +{ + my($self) = @_; + + print 'Option', ' ' x ($fieldWidth - length('Option') ), "Value\n"; + + for (sort byOrder keys(%{$self -> {'opt'} }) ) + { + print "-$_", ' ' x ($fieldWidth - (1 + length) ), "${$self->{'opt'} }{$_}\n"; + } + + print "\n"; + +} # End of dumpOptions. + +# -------------------------------------------------------------------------- +# Return: +# 0 -> Error. +# 1 -> Ok. + +sub getOptions +{ + push(@_, 0) if ($#_ == 2); # Default for $ignoreCase is 0. + push(@_, 1) if ($#_ == 3); # Default for $helpThenExit is 1. + + my($self, $default, $helpText, $versionText, + $helpThenExit, $versionThenExit, $ignoreCase) = @_; + + $helpThenExit = 1 unless (defined($helpThenExit)); + $versionThenExit = 1 unless (defined($versionThenExit)); + $ignoreCase = 0 unless (defined($ignoreCase)); + + $self -> {'default'} = $default; + $self -> {'helpText'} = $helpText; + $self -> {'versionText'} = $versionText; + $Getopt::Long::ignorecase = $ignoreCase; + + unless (defined($self -> {'default'}{'help'})) + { + $self -> {'default'}{'help'} = + { + type => ':i', + default => '', + linkage => sub {$self->helpOptions($_[1]); exit (0) if $helpThenExit;}, + verbose => "print help and exit" + }; + } + + unless (defined($self -> {'default'}{'version'})) + { + $self -> {'default'}{'version'} = + { + type => '', + default => '', + linkage => sub {print $self->{'versionText'}; exit (0) if versionTheExit;}, + verbose => "print version and exit" + }; + } + + for (keys(%{$self -> {'default'} }) ) + { + my $type = ${$self -> {'default'} }{$_}{'type'}; + push(@{$self -> {'type'} }, "$_$type"); + $self->{'opt'}->{$_} = ${$self -> {'default'} }{$_}{'linkage'} + if ${$self -> {'default'} }{$_}{'linkage'}; + } + + my($result) = &GetOptions($self -> {'opt'}, @{$self -> {'type'} }); + + return $result unless $result; + + for (keys(%{$self -> {'default'} }) ) + { + if (! defined(${$self -> {'opt'} }{$_})) #{ + { + ${$self -> {'opt'} }{$_} = ${$self -> {'default'} }{$_}{'default'}; + } + } + + $result; +} # End of getOptions. + +# -------------------------------------------------------------------------- + +sub helpOptions +{ + my($self) = shift; + my($noHelp) = shift; + $noHelp = 0 unless $noHelp; + my($optwidth, $typewidth, $defaultwidth, $maxlinewidth, $valind, $valwidth) + = (10, 5, 9, 78, 4, 11); + + print "$self->{'helpText'}" if ($self -> {'helpText'}); + + print ' Option', ' ' x ($optwidth - length('Option') -1 ), + 'Type', ' ' x ($typewidth - length('Type') + 1), + 'Default', ' ' x ($defaultwidth - length('Default') ), + "Description\n"; + + for (sort byOrder keys(%{$self -> {'default'} }) ) + { + my($line, $help, $option, $val); + $option = $_; + next if ${$self->{'default'} }{$_}{'noHelp'} && ${$self->{'default'} }{$_}{'noHelp'} > $noHelp; + $line = " -$_ " . ' ' x ($optwidth - (2 + length) ) . + "${$self->{'default'} }{$_}{'type'} ". + ' ' x ($typewidth - (1+length(${$self -> {'default'} }{$_}{'type'}) )); + + $val = ${$self->{'default'} }{$_}{'linkage'}; + if ($val) + { + if (ref($val) eq 'SCALAR') + { + $val = $$val; + } + else + { + $val = ''; + } + } + else + { + $val = ${$self->{'default'} }{$_}{'default'}; + } + $line .= "$val "; + $line .= ' ' x ($optwidth + $typewidth + $defaultwidth + 1 - length($line)); + + if (defined(${$self -> {'default'} }{$_}{'verbose'}) && + ${$self -> {'default'} }{$_}{'verbose'} ne '') + { + $help = "${$self->{'default'} }{$_}{'verbose'}"; + } + else + { + $help = ' '; + } + if ((length("$line") + length($help)) < $maxlinewidth) + { + print $line , $help, "\n"; + } + else + { + print $line, "\n", ' ' x $valind, $help, "\n"; + } + for $val (sort byOrder keys(%{${$self->{'default'}}{$option}{'values'}})) + { + print ' ' x ($valind + 2); + print $val, ' ', ' ' x ($valwidth - length($val) - 2); + print ${$self->{'default'}}{$option}{'values'}{$val}, "\n"; + } + } + + print <| ! no argument: variable is set to 1 on -foo (or, to 0 on -nofoo) + =s | :s mandatory (or, optional) string argument + =i | :i mandatory (or, optional) integer argument +EOT +} # End of helpOptions. + +#------------------------------------------------------------------- + +sub new +{ + my($class) = @_; + my($self) = {}; + $self -> {'default'} = {}; + $self -> {'helpText'} = ''; + $self -> {'opt'} = {}; + $opt = $self -> {'opt'}; # An alias for $self -> {'opt'}. + $self -> {'type'} = (); + + return bless $self, $class; + +} # End of new. + +# -------------------------------------------------------------------------- + +1; + +# End MySimple.pm + +require "$ENV{T2H_HOME}/MySimple.pm" + if ($0 =~ /\.pl$/ && + -e "$ENV{T2H_HOME}/texi2html.init" && -r "$ENV{T2H_HOME}/texi2html.init"); + +package main; + +#+++############################################################################ +# # +# Constants # +# # +#---############################################################################ + +$DEBUG_TOC = 1; +$DEBUG_INDEX = 2; +$DEBUG_BIB = 4; +$DEBUG_GLOSS = 8; +$DEBUG_DEF = 16; +$DEBUG_HTML = 32; +$DEBUG_USER = 64; +$DEBUG_L2H = 128; + + +$BIBRE = '\[[\w\/-]+\]'; # RE for a bibliography reference +$FILERE = '[\/\w.+-]+'; # RE for a file name +$VARRE = '[^\s\{\}]+'; # RE for a variable name +$NODERE = '[^,:]+'; # RE for a node name +$NODESRE = '[^:]+'; # RE for a list of node names + +$ERROR = "***"; # prefix for errors +$WARN = "**"; # prefix for warnings + + # program home page +$PROTECTTAG = "_ThisIsProtected_"; # tag to recognize protected sections + +$CHAPTEREND = "\n"; # to know where a chpater ends +$SECTIONEND = "\n"; # to know where section ends +$TOPEND = "\n"; # to know where top ends + + + +# +# pre-defined indices +# +$index_properties = +{ + 'c' => { name => 'cp'}, + 'f' => { name => 'fn', code => 1}, + 'v' => { name => 'vr', code => 1}, + 'k' => { name => 'ky', code => 1}, + 'p' => { name => 'pg', code => 1}, + 't' => { name => 'tp', code => 1} +}; + + +%predefined_index = ( + 'cp', 'c', + 'fn', 'f', + 'vr', 'v', + 'ky', 'k', + 'pg', 'p', + 'tp', 't', + ); + +# +# valid indices +# +%valid_index = ( + 'c', 1, + 'f', 1, + 'v', 1, + 'k', 1, + 'p', 1, + 't', 1, + ); + +# +# texinfo section names to level +# +%sec2level = ( + 'top', 0, + 'chapter', 1, + 'unnumbered', 1, + 'majorheading', 1, + 'chapheading', 1, + 'appendix', 1, + 'section', 2, + 'unnumberedsec', 2, + 'heading', 2, + 'appendixsec', 2, + 'appendixsection', 2, + 'subsection', 3, + 'unnumberedsubsec', 3, + 'subheading', 3, + 'appendixsubsec', 3, + 'subsubsection', 4, + 'unnumberedsubsubsec', 4, + 'subsubheading', 4, + 'appendixsubsubsec', 4, + ); + +# +# accent map, TeX command to ISO name +# +%accent_map = ( + '"', 'uml', + '~', 'tilde', + '^', 'circ', + '`', 'grave', + '\'', 'acute', + ); + +# +# texinfo "simple things" (@foo) to HTML ones +# +%simple_map = ( + # cf. makeinfo.c + "*", "
    ", # HTML+ + " ", " ", + "\t", " ", + "-", "­", # soft hyphen + "\n", "\n", + "|", "", + 'tab', '<\/TD>
    Button Name Go to From 1.2.3 go to
    +EOT + $about .= + ($T2H_ICONS && $T2H_ACTIVE_ICONS{$button} ? + &$T2H_button_icon_img($button, $T2H_ACTIVE_ICONS{$button}) : + " [" . $T2H_NAVIGATION_TEXT{$button} . "] "); + $about .= < + +$button + +$T2H_BUTTONS_GOTO{$button} + +$T2H_BUTTONS_EXAMPLE{$button} +
    ', + # spacing commands + ":", "", + "!", "!", + "?", "?", + ".", ".", + "-", "", + ); + +# +# texinfo "things" (@foo{}) to HTML ones +# +%things_map = ( + 'TeX', 'TeX', + 'br', '

    ', # paragraph break + 'bullet', '*', + 'copyright', '(C)', + 'dots', '...<\/small>', + 'enddots', '....<\/small>', + 'equiv', '==', + 'error', 'error-->', + 'expansion', '==>', + 'minus', '-', + 'point', '-!-', + 'print', '-|', + 'result', '=>', + 'today', $T2H_TODAY, + 'aa', 'å', + 'AA', 'Å', + 'ae', 'æ', + 'oe', 'œ', + 'AE', 'Æ', + 'OE', 'Œ', + 'o', 'ø', + 'O', 'Ø', + 'ss', 'ß', + 'l', '\/l', + 'L', '\/L', + 'exclamdown', '¡', + 'questiondown', '¿', + 'pounds', '£' + ); + +# +# texinfo styles (@foo{bar}) to HTML ones +# +%style_map = ( + 'acronym', '&do_acronym', + 'asis', '', + 'b', 'B', + 'cite', 'CITE', + 'code', 'CODE', + 'command', 'CODE', + 'ctrl', '&do_ctrl', # special case + 'dfn', 'EM', # DFN tag is illegal in the standard + 'dmn', '', # useless + 'email', '&do_email', # insert a clickable email address + 'emph', 'EM', + 'env', 'CODE', + 'file', '"TT', # will put quotes, cf. &apply_style + 'i', 'I', + 'kbd', 'KBD', + 'key', 'KBD', + 'math', '&do_math', + 'option', '"SAMP', # will put quotes, cf. &apply_style + 'r', '', # unsupported + 'samp', '"SAMP', # will put quotes, cf. &apply_style + 'sc', '&do_sc', # special case + 'strong', 'STRONG', + 't', 'TT', + 'titlefont', '', # useless + 'uref', '&do_uref', # insert a clickable URL + 'url', '&do_url', # insert a clickable URL + 'var', 'VAR', + 'w', '', # unsupported + 'H', '&do_accent', + 'dotaccent', '&do_accent', + 'ringaccent','&do_accent', + 'tieaccent', '&do_accent', + 'u','&do_accent', + 'ubaraccent','&do_accent', + 'udotaccent','&do_accent', + 'v', '&do_accent', + ',', '&do_accent', + 'dotless', '&do_accent' + ); + +# +# texinfo format (@foo/@end foo) to HTML ones +# +%format_map = ( + 'quotation', 'BLOCKQUOTE', + # lists + 'itemize', 'UL', + 'enumerate', 'OL', + # poorly supported + 'flushleft', 'PRE', + 'flushright', 'PRE', + ); + +# +# an eval of these $complex_format_map->{what}->[0] yields beginning +# an eval of these $complex_format_map->{what}->[1] yieleds end +$complex_format_map = +{ + example => + [ + q{"$T2H_EXAMPLE_INDENT_CELL
    "},
+  q{'
    '} + ], + smallexample => + [ + q{"$T2H_SMALL_EXAMPLE_INDENT_CELL
    "},
+  q{'
    '} + ], + display => + [ + q{"$T2H_EXAMPLE_INDENT_CELL
    '},
+  q{'
    '} + ], + smalldisplay => + [ + q{"$T2H_SMALL_EXAMPLE_INDENT_CELL
    '},
+  q{'
    '} + ] +}; + +$complex_format_map->{lisp} = $complex_format_map->{example}; +$complex_format_map->{smalllisp} = $complex_format_map->{smallexample}; +$complex_format_map->{format} = $complex_format_map->{display}; +$complex_format_map->{smallformat} = $complex_format_map->{smalldisplay}; + +# +# texinfo definition shortcuts to real ones +# +%def_map = ( + # basic commands + 'deffn', 0, + 'defvr', 0, + 'deftypefn', 0, + 'deftypevr', 0, + 'defcv', 0, + 'defop', 0, + 'deftp', 0, + # basic x commands + 'deffnx', 0, + 'defvrx', 0, + 'deftypefnx', 0, + 'deftypevrx', 0, + 'defcvx', 0, + 'defopx', 0, + 'deftpx', 0, + # shortcuts + 'defun', 'deffn Function', + 'defmac', 'deffn Macro', + 'defspec', 'deffn {Special Form}', + 'defvar', 'defvr Variable', + 'defopt', 'defvr {User Option}', + 'deftypefun', 'deftypefn Function', + 'deftypevar', 'deftypevr Variable', + 'defivar', 'defcv {Instance Variable}', + 'deftypeivar', 'defcv {Instance Variable}', # NEW: FIXME + 'defmethod', 'defop Method', + 'deftypemethod', 'defop Method', # NEW:FIXME + # x shortcuts + 'defunx', 'deffnx Function', + 'defmacx', 'deffnx Macro', + 'defspecx', 'deffnx {Special Form}', + 'defvarx', 'defvrx Variable', + 'defoptx', 'defvrx {User Option}', + 'deftypefunx', 'deftypefnx Function', + 'deftypevarx', 'deftypevrx Variable', + 'defivarx', 'defcvx {Instance Variable}', + 'defmethodx', 'defopx Method', + ); + +# +# things to skip +# +%to_skip = ( + # comments + 'c', 1, + 'comment', 1, + 'ifnotinfo', 1, + 'ifnottex', 1, + 'ifhtml', 1, + 'end ifhtml', 1, + 'end ifnotinfo', 1, + 'end ifnottex', 1, + # useless + 'detailmenu', 1, + 'direntry', 1, + 'contents', 1, + 'shortcontents', 1, + 'summarycontents', 1, + 'footnotestyle', 1, + 'end ifclear', 1, + 'end ifset', 1, + 'titlepage', 1, + 'end titlepage', 1, + # unsupported commands (formatting) + 'afourpaper', 1, + 'cropmarks', 1, + 'finalout', 1, + 'headings', 1, + 'sp', 1, + 'need', 1, + 'page', 1, + 'setchapternewpage', 1, + 'everyheading', 1, + 'everyfooting', 1, + 'evenheading', 1, + 'evenfooting', 1, + 'oddheading', 1, + 'oddfooting', 1, + 'smallbook', 1, + 'vskip', 1, + 'filbreak', 1, + 'paragraphindent', 1, + # unsupported formats + 'cartouche', 1, + 'end cartouche', 1, + 'group', 1, + 'end group', 1, + ); + +#+++############################################################################ +# # +# Argument parsing, initialisation # +# # +#---############################################################################ + +# +# flush stdout and stderr after every write +# +select(STDERR); +$| = 1; +select(STDOUT); +$| = 1; + + +%value = (); # hold texinfo variables, see also -D +$use_bibliography = 1; +$use_acc = 1; + +# +# called on -init-file +sub LoadInitFile +{ + my $init_file = shift; + # second argument is value of options + $init_file = shift; + if (-f $init_file) + { + print "# reading initialization file from $init_file\n" + if ($T2H_VERBOSE); + require($init_file); + } + else + { + print "$ERROR Error: can't read init file $int_file\n"; + $init_file = ''; + } +} + +# +# called on -lang +sub SetDocumentLanguage +{ + my $lang = shift; + if (! exists($T2H_WORDS->{$lang})) + { + warn "$ERROR: Language specs for '$lang' do not exists. Reverting to '" . + ($T2H_LANG ? T2H_LANG : "en") . "'\n"; + } + else + { + print "# using '$lang' as document language\n" if ($T2H_VERBOSE); + $T2H_LANG = $lang; + } +} + +## +## obsolete cmd line options +## +$T2H_OBSOLETE_OPTIONS -> {'no-section_navigation'} = +{ + type => '!', + linkage => sub {$main::T2H_SECTION_NAVIGATION = 0;}, + verbose => 'obsolete, use -nosec_nav', + noHelp => 2, +}; +$T2H_OBSOLETE_OPTIONS -> {use_acc} = +{ + type => '!', + linkage => \$use_acc, + verbose => 'obsolete', + noHelp => 2 +}; +$T2H_OBSOLETE_OPTIONS -> {expandinfo} = +{ + type => '!', + linkage => sub {$main::T2H_EXPAND = 'info';}, + verbose => 'obsolete, use "-expand info" instead', + noHelp => 2, +}; +$T2H_OBSOLETE_OPTIONS -> {expandtex} = +{ + type => '!', + linkage => sub {$main::T2H_EXPAND = 'tex';}, + verbose => 'obsolete, use "-expand tex" instead', + noHelp => 2, +}; +$T2H_OBSOLETE_OPTIONS -> {monolithic} = +{ + type => '!', + linkage => sub {$main::T2H_SPLIT = '';}, + verbose => 'obsolete, use "-split no" instead', + noHelp => 2 +}; +$T2H_OBSOLETE_OPTIONS -> {split_node} = +{ + type => '!', + linkage => sub{$main::T2H_SPLIT = 'section';}, + verbose => 'obsolete, use "-split section" instead', + noHelp => 2, +}; +$T2H_OBSOLETE_OPTIONS -> {split_chapter} = +{ + type => '!', + linkage => sub{$main::T2H_SPLIT = 'chapter';}, + verbose => 'obsolete, use "-split chapter" instead', + noHelp => 2, +}; +$T2H_OBSOLETE_OPTIONS -> {no_verbose} = +{ + type => '!', + linkage => sub {$main::T2H_VERBOSE = 0;}, + verbose => 'obsolete, use -noverbose instead', + noHelp => 2, +}; +$T2H_OBSOLETE_OPTIONS -> {output_file} = +{ + type => '=s', + linkage => sub {$main::T2H_OUT = @_[1]; $T2H_SPLIT = '';}, + verbose => 'obsolete, use -out_file instead', + noHelp => 2 +}; + +$T2H_OBSOLETE_OPTIONS -> {section_navigation} = +{ + type => '!', + linkage => \$T2H_SECTION_NAVIGATION, + verbose => 'obsolete, use -sec_nav instead', + noHelp => 2, +}; + +$T2H_OBSOLETE_OPTIONS -> {verbose} = +{ + type => '!', + linkage => \$T2H_VERBOSE, + verbose => 'obsolete, use -Verbose instead', + noHelp => 2 +}; + +# read initialzation from $sysconfdir/texi2htmlrc or $HOME/.texi2htmlrc +my $home = $ENV{HOME}; +defined($home) or $home = ''; +foreach $i ('/usr/local/etc/texi2htmlrc', "$home/.texi2htmlrc") { + if (-f $i) { + print "# reading initialization file from $i\n" + if ($T2H_VERBOSE); + require($i); + } +} + + +#+++############################################################################ +# # +# parse command-line options +# # +#---############################################################################ +$T2H_USAGE_TEXT = <getOptions($T2H_OPTIONS, $T2H_USAGE_TEXT, "$THISVERSION\n")) +{ + print $Configure_failed if $Configure_failed; + die $T2H_FAILURE_TEXT; +} + +if (@ARGV > 1) +{ + eval {Getopt::Long::Configure("no_pass_through");}; + if (! $options->getOptions($T2H_OBSOLETE_OPTIONS, $T2H_USAGE_TEXT, "$THISVERSION\n")) + { + print $Configure_failed if $Configure_failed; + die $T2H_FAILURE_TEXT; + } +} + +if ($T2H_CHECK) { + die "Need file to check\n$T2H_FAILURE_TEXT" unless @ARGV > 0; + ✓ + exit; +} + +#+++############################################################################ +# # +# evaluation of cmd line options +# # +#---############################################################################ + +if ($T2H_EXPAND eq 'info') +{ + $to_skip{'ifinfo'} = 1; + $to_skip{'end ifinfo'} = 1; +} +elsif ($T2H_EXPAND eq 'tex') +{ + $to_skip{'iftex'} = 1; + $to_skip{'end iftex'} = 1; + +} + +$T2H_INVISIBLE_MARK = '' if $T2H_INVISIBLE_MARK eq 'xbm'; + +# +# file name buisness +# +die "Need exactly one file to translate\n$T2H_FAILURE_TEXT" unless @ARGV == 1; +$docu = shift(@ARGV); +if ($docu =~ /.*\//) { + chop($docu_dir = $&); + $docu_name = $'; +} else { + $docu_dir = '.'; + $docu_name = $docu; +} +unshift(@T2H_INCLUDE_DIRS, $docu_dir); +$docu_name =~ s/\.te?x(i|info)?$//; # basename of the document +$docu_name = $T2H_PREFIX if ($T2H_PREFIX); + +# subdir +if ($T2H_SUBDIR && ! $T2H_OUT) +{ + $T2H_SUBDIR =~ s|/*$||; + unless (-d "$T2H_SUBDIR" && -w "$T2H_SUBDIR") + { + if ( mkdir($T2H_SUBDIR, oct(755))) + { + print "# created directory $T2H_SUBDIR\n" if ($T2H_VERBOSE); + } + else + { + warn "$ERROR can't create directory $T2H_SUBDIR. Put results into current directory\n"; + $T2H_SUBDIR = ''; + } + } +} + +if ($T2H_SUBDIR && ! $T2H_OUT) +{ + $docu_rdir = "$T2H_SUBDIR/"; + print "# putting result files into directory $docu_rdir\n" if ($T2H_VERBOSE); +} +else +{ + if ($T2H_OUT && $T2H_OUT =~ m|(.*)/|) + { + $docu_rdir = "$1/"; + print "# putting result files into directory $docu_rdir\n" if ($T2H_VERBOSE); + } + else + { + print "# putting result files into current directory \n" if ($T2H_VERBOSE); + $docu_rdir = ''; + } +} + +# extension +if ($T2H_SHORTEXTN) +{ + $docu_ext = "htm"; +} +else +{ + $docu_ext = "html"; +} +if ($T2H_TOP_FILE =~ /\..*$/) +{ + $T2H_TOP_FILE = $`.".$docu_ext"; +} + +# result files +if (! $T2H_OUT && ($T2H_SPLIT =~ /section/i || $T2H_SPLIT =~ /node/i)) +{ + $T2H_SPLIT = 'section'; +} +elsif (! $T2H_OUT && $T2H_SPLIT =~ /chapter/i) +{ + $T2H_SPLIT = 'chapter' +} +else +{ + undef $T2H_SPLIT; +} + +$docu_doc = "$docu_name.$docu_ext"; # document's contents +$docu_doc_file = "$docu_rdir$docu_doc"; +if ($T2H_SPLIT) +{ + $docu_toc = $T2H_TOC_FILE || "${docu_name}_toc.$docu_ext"; # document's table of contents + $docu_stoc = "${docu_name}_ovr.$docu_ext"; # document's short toc + $docu_foot = "${docu_name}_fot.$docu_ext"; # document's footnotes + $docu_about = "${docu_name}_abt.$docu_ext"; # about this document + $docu_top = $T2H_TOP_FILE || $docu_doc; +} +else +{ + if ($T2H_OUT) + { + $docu_doc = $T2H_OUT; + $docu_doc =~ s|.*/||; + } + $docu_toc = $docu_foot = $docu_stoc = $docu_about = $docu_top = $docu_doc; +} + +$docu_toc_file = "$docu_rdir$docu_toc"; +$docu_stoc_file = "$docu_rdir$docu_stoc"; +$docu_foot_file = "$docu_rdir$docu_foot"; +$docu_about_file = "$docu_rdir$docu_about"; +$docu_top_file = "$docu_rdir$docu_top"; + +$docu_frame_file = "$docu_rdir${docu_name}_frame.$docu_ext"; +$docu_toc_frame_file = "$docu_rdir${docu_name}_toc_frame.$docu_ext"; + +# +# variables +# +$value{'html'} = 1; # predefine html (the output format) +$value{'texi2html'} = $THISVERSION; # predefine texi2html (the translator) +# _foo: internal to track @foo +foreach ('_author', '_title', '_subtitle', + '_settitle', '_setfilename', '_shorttitle') { + $value{$_} = ''; # prevent -w warnings +} +%node2sec = (); # node to section name +%sec2node = (); # section to node name +%sec2number = (); # section to number +%number2sec = (); # number to section +%idx2node = (); # index keys to node +%node2href = (); # node to HREF +%node2next = (); # node to next +%node2prev = (); # node to prev +%node2up = (); # node to up +%bib2href = (); # bibliography reference to HREF +%gloss2href = (); # glossary term to HREF +@sections = (); # list of sections +%tag2pro = (); # protected sections + +# +# initial indexes +# +$bib_num = 0; +$foot_num = 0; +$gloss_num = 0; +$idx_num = 0; +$sec_num = 0; +$doc_num = 0; +$html_num = 0; + +# +# can I use ISO8879 characters? (HTML+) +# +if ($T2H_USE_ISO) { + $things_map{'bullet'} = "•"; + $things_map{'copyright'} = "©"; + $things_map{'dots'} = "…"; + $things_map{'equiv'} = "≡"; + $things_map{'expansion'} = "→"; + $things_map{'point'} = "∗"; + $things_map{'result'} = "⇒"; +} + +# +# read texi2html extensions (if any) +# +$extensions = 'texi2html.ext'; # extensions in working directory +if (-f $extensions) { + print "# reading extensions from $extensions\n" if $T2H_VERBOSE; + require($extensions); +} +($progdir = $0) =~ s/[^\/]+$//; +if ($progdir && ($progdir ne './')) { + $extensions = "${progdir}texi2html.ext"; # extensions in texi2html directory + if (-f $extensions) { + print "# reading extensions from $extensions\n" if $T2H_VERBOSE; + require($extensions); + } +} + + +print "# reading from $docu\n" if $T2H_VERBOSE; + +######################################################################### +# +# latex2html stuff +# +# latex2html conversions consist of three stages: +# 1) ToLatex: Put "latex" code into a latex file +# 2) ToHtml: Use latex2html to generate corresponding html code and images +# 3) FromHtml: Extract generated code and images from latex2html run +# + +########################## +# default settings +# + +# defaults for files and names + +sub l2h_Init +{ + local($root) = @_; + + return 0 unless ($root); + + $l2h_name = "${root}_l2h"; + + $l2h_latex_file = "$docu_rdir${l2h_name}.tex"; + $l2h_cache_file = "${docu_rdir}l2h_cache.pm"; + $T2H_L2H_L2H = "latex2html" unless ($T2H_L2H_L2H); + + # destination dir -- generated images are put there, should be the same + # as dir of enclosing html document -- + $l2h_html_file = "$docu_rdir${l2h_name}.html"; + $l2h_prefix = "${l2h_name}_"; + return 1; +} + + +########################## +# +# First stage: Generation of Latex file +# Initialize with: l2h_InitToLatex +# Add content with: l2h_ToLatex($text) --> HTML placeholder comment +# Finish with: l2h_FinishToLatex +# + +$l2h_latex_preample = <$l2h_latex_file")) + { + warn "$ERROR Error l2h: Can't open latex file '$latex_file' for writing\n"; + return 0; + } + print "# l2h: use ${l2h_latex_file} as latex file\n" if ($T2H_VERBOSE); + print L2H_LATEX $l2h_latex_preample; + } + # open database for caching + l2h_InitCache(); + $l2h_latex_count = 0; + $l2h_to_latex_count = 0; + $l2h_cached_count = 0; + return 1; +} + +# print text (1st arg) into latex file (if not already there), return +# HTML commentary which can be later on replaced by the latex2html +# generated text +sub l2h_ToLatex +{ + my($text) = @_; + my($count); + + $l2h_to_latex_count++; + $text =~ s/(\s*)$//; + + # try whether we can cache it + my $cached_text = l2h_FromCache($text); + if ($cached_text) + { + $l2h_cached_count++; + return $cached_text; + } + + # try whether we have text already on things to do + unless ($count = $l2h_to_latex{$text}) + { + $count = $l2h_latex_count; + $l2h_latex_count++; + $l2h_to_latex{$text} = $count; + $l2h_to_latex[$count] = $text; + unless ($T2H_L2H_SKIP) + { + print L2H_LATEX "\\begin{rawhtml}\n"; + print L2H_LATEX "\n"; + print L2H_LATEX "\\end{rawhtml}\n"; + + print L2H_LATEX "$text\n"; + + print L2H_LATEX "\\begin{rawhtml}\n"; + print L2H_LATEX "\n"; + print L2H_LATEX "\\end{rawhtml}\n"; + } + } + return ""; +} + +# print closing into latex file and close it +sub l2h_FinishToLatex +{ + local ($reused); + + $reused = $l2h_to_latex_count - $l2h_latex_count - $l2h_cached_count; + unless ($T2H_L2H_SKIP) + { + print L2H_LATEX $l2h_latex_closing; + close(L2H_LATEX); + } + print "# l2h: finished to latex ($l2h_cached_count cached, $reused reused, $l2h_latex_count contents)\n" if ($T2H_VERBOSE); + unless ($l2h_latex_count) + { + l2h_Finish(); + return 0; + } + return 1; +} + +################################### +# Second stage: Use latex2html to generate corresponding html code and images +# +# l2h_ToHtml([$l2h_latex_file, [$l2h_html_dir]]): +# Call latex2html on $l2h_latex_file +# Put images (prefixed with $l2h_name."_") and html file(s) in $l2h_html_dir +# Return 1, on success +# 0, otherwise +# +sub l2h_ToHtml +{ + local($call, $ext, $root, $dotbug); + + if ($T2H_L2H_SKIP) + { + print "# l2h: skipping latex2html run\n" if ($T2H_VERBOSE); + return 1; + } + + # Check for dot in directory where dvips will work + if ($T2H_L2H_TMP) + { + if ($T2H_L2H_TMP =~ /\./) + { + warn "$ERROR Warning l2h: l2h_tmp dir contains a dot. Use /tmp, instead\n"; + $dotbug = 1; + } + } + else + { + if (&getcwd =~ /\./) + { + warn "$ERROR Warning l2h: current dir contains a dot. Use /tmp as l2h_tmp dir \n"; + $dotbug = 1; + } + } + # fix it, if necessary and hope that it works + $T2H_L2H_TMP = "/tmp" if ($dotbug); + + $call = $T2H_L2H_L2H; + # use init file, if specified + $call = $call . " -init_file " . $init_file if ($init_file && -f $init_file); + # set output dir + $call .= ($docu_rdir ? " -dir $docu_rdir" : " -no_subdir"); + # use l2h_tmp, if specified + $call = $call . " -tmp $T2H_L2H_TMP" if ($T2H_L2H_TMP); + # options we want to be sure of + $call = $call ." -address 0 -info 0 -split 0 -no_navigation -no_auto_link"; + $call = $call ." -prefix ${l2h_prefix} $l2h_latex_file"; + + print "# l2h: executing '$call'\n" if ($T2H_VERBOSE); + if (system($call)) + { + warn "l2h ***Error: '${call}' did not succeed\n"; + return 0; + } + else + { + print "# l2h: latex2html finished successfully\n" if ($T2H_VERBOSE); + return 1; + } +} + +# this is directly pasted over from latex2html +sub getcwd { + local($_) = `pwd`; + + die "'pwd' failed (out of memory?)\n" + unless length; + chop; + $_; +} + + +########################## +# Third stage: Extract generated contents from latex2html run +# Initialize with: l2h_InitFromHtml +# open $l2h_html_file for reading +# reads in contents into array indexed by numbers +# return 1, on success -- 0, otherwise +# Extract Html code with: l2h_FromHtml($text) +# replaces in $text all previosuly inserted comments by generated html code +# returns (possibly changed) $text +# Finish with: l2h_FinishFromHtml +# closes $l2h_html_dir/$l2h_name.".$docu_ext" + +sub l2h_InitFromHtml +{ + local($h_line, $h_content, $count, %l2h_img); + + if (! open(L2H_HTML, "<${l2h_html_file}")) + { + print "$ERROR Error l2h: Can't open ${l2h_html_file} for reading\n"; + return 0; + } + print "# l2h: use ${l2h_html_file} as html file\n" if ($T2H_VERBOSE); + + $l2h_html_count = 0; + + while ($h_line = ) + { + if ($h_line =~ /^/) + { + $count = $1; + $h_content = ""; + while ($h_line = ) + { + if ($h_line =~ /^/) + { + chomp $h_content; + chomp $h_content; + $l2h_html_count++; + $h_content = l2h_ToCache($count, $h_content); + $l2h_from_html[$count] = $h_content; + $h_content = ''; + last; + } + $h_content = $h_content.$h_line; + } + if ($hcontent) + { + print "$ERROR Warning l2h: l2h_end $l2h_name $count not found\n" + if ($T2H_VERBOSE); + close(L2H_HTML); + return 0; + } + } + } + print "# l2h: Got $l2h_html_count of $l2h_latex_count html contents\n" + if ($T2H_VERBOSE); + + close(L2H_HTML); + return 1; +} + +sub l2h_FromHtml +{ + local($text) = @_; + local($done, $to_do, $count); + + $to_do = $text; + + while ($to_do =~ /([^\000]*)([^\000]*)/) + { + $to_do = $1; + $count = $2; + $done = $3.$done; + + $done = "".$done + if ($T2H_DEBUG & $DEBUG_L2H); + + $done = &l2h_ExtractFromHtml($count) . $done; + + $done = "".$done + if ($T2H_DEBUG & $DEBUG_L2H); + } + return $to_do.$done; +} + + +sub l2h_ExtractFromHtml +{ + local($count) = @_; + + return $l2h_from_html[$count] if ($l2h_from_html[$count]); + + if ($count >= 0 && $count < $l2h_latex_count) + { + # now we are in trouble + local($l_l2h, $_); + + $l2h_extract_error++; + print "$ERROR l2h: can't extract content $count from html\n" + if ($T2H_VERBOSE); + # try simple (ordinary) substition (without l2h) + $l_l2h = $T2H_L2H; + $T2H_L2H = 0; + $_ = $l2h_to_latex{$count}; + $_ = &substitute_style($_); + &unprotect_texi; + $_ = "" . $_ + if ($T2H_DEBUG & $DEBUG_L2H); + $T2H_L2H = $l_l2h; + return $_; + } + else + { + # now we have been incorrectly called + $l2h_range_error++; + print "$ERROR l2h: Request of $count content which is out of valide range [0,$l2h_latex_count)\n"; + return "" + if ($T2H_DEBUG & $DEBUG_L2H); + return ""; + } +} + +sub l2h_FinishFromHtml +{ + if ($T2H_VERBOSE) + { + if ($l2h_extract_error + $l2h_range_error) + { + print "# l2h: finished from html ($l2h_extract_error extract and $l2h_range_error errors)\n"; + } + else + { + print "# l2h: finished from html (no errors)\n"; + } + } +} + +sub l2h_Finish +{ + l2h_StoreCache(); + if ($T2H_L2H_CLEAN) + { + print "# l2h: removing temporary files generated by l2h extension\n" + if $T2H_VERBOSE; + while (<"$docu_rdir$l2h_name"*>) + { + unlink $_; + } + } + print "# l2h: Finished\n" if $T2H_VERBOSE; + return 1; +} + +############################## +# stuff for l2h caching +# + +# I tried doing this with a dbm data base, but it did not store all +# keys/values. Hence, I did as latex2html does it +sub l2h_InitCache +{ + if (-r "$l2h_cache_file") + { + my $rdo = do "$l2h_cache_file"; + warn("$ERROR l2h Error: could not load $docu_rdir$l2h_cache_file: $@\n") + unless ($rdo); + } +} + +sub l2h_StoreCache +{ + return unless $l2h_latex_count; + + my ($key, $value); + open(FH, ">$l2h_cache_file") || return warn"$ERROR l2h Error: could not open $docu_rdir$l2h_cache_file for writing: $!\n"; + + + while (($key, $value) = each %l2h_cache) + { + # escape stuff + $key =~ s|/|\\/|g; + $key =~ s|\\\\/|\\/|g; + # weird, a \ at the end of the key results in an error + # maybe this also broke the dbm database stuff + $key =~ s|\\$|\\\\|; + $value =~ s/\|/\\\|/g; + $value =~ s/\\\\\|/\\\|/g; + $value =~ s|\\\\|\\\\\\\\|g; + print FH "\n\$l2h_cache_key = q/$key/;\n"; + print FH "\$l2h_cache{\$l2h_cache_key} = q|$value|;\n"; + } + print FH "1;"; + close(FH); +} + +# return cached html, if it exists for text, and if all pictures +# are there, as well +sub l2h_FromCache +{ + my $text = shift; + my $cached = $l2h_cache{$text}; + if ($cached) + { + while ($cached =~ m/SRC="(.*?)"/g) + { + unless (-e "$docu_rdir$1") + { + return undef; + } + } + return $cached; + } + return undef; +} + +# insert generated html into cache, move away images, +# return transformed html +$maximage = 1; +sub l2h_ToCache +{ + my $count = shift; + my $content = shift; + my @images = ($content =~ /SRC="(.*?)"/g); + my ($src, $dest); + + for $src (@images) + { + $dest = $l2h_img{$src}; + unless ($dest) + { + my $ext; + if ($src =~ /.*\.(.*)$/ && $1 ne $docu_ext) + { + $ext = $1; + } + else + { + warn "$ERROR: L2h image $src has invalid extension\n"; + next; + } + while (-e "$docu_rdir${docu_name}_$maximage.$ext") { $maximage++;} + $dest = "${docu_name}_$maximage.$ext"; + system("cp -f $docu_rdir$src $docu_rdir$dest"); + $l2h_img{$src} = $dest; + unlink "$docu_rdir$src" unless ($DEBUG & DEBUG_L2H); + } + $content =~ s/$src/$dest/g; + } + $l2h_cache{$l2h_to_latex[$count]} = $content; + return $content; +} + + +#+++############################################################################ +# # +# Pass 1: read source, handle command, variable, simple substitution # +# # +#---############################################################################ + +@lines = (); # whole document +@toc_lines = (); # table of contents +@stoc_lines = (); # table of contents +$curlevel = 0; # current level in TOC +$node = ''; # current node name +$node_next = ''; # current node next name +$node_prev = ''; # current node prev name +$node_up = ''; # current node up name +$in_table = 0; # am I inside a table +$table_type = ''; # type of table ('', 'f', 'v', 'multi') +@tables = (); # nested table support +$in_bibliography = 0; # am I inside a bibliography +$in_glossary = 0; # am I inside a glossary +$in_top = 0; # am I inside the top node +$has_top = 0; # did I see a top node? +$has_top_command = 0; # did I see @top for automatic pointers? +$in_pre = 0; # am I inside a preformatted section +$in_list = 0; # am I inside a list +$in_html = 0; # am I inside an HTML section +$first_line = 1; # is it the first line +$dont_html = 0; # don't protect HTML on this line +$deferred_ref = ''; # deferred reference for indexes +@html_stack = (); # HTML elements stack +$html_element = ''; # current HTML element +&html_reset; +%macros = (); # macros + +# init l2h +$T2H_L2H = &l2h_Init($docu_name) if ($T2H_L2H); +$T2H_L2H = &l2h_InitToLatex if ($T2H_L2H); + +# build code for simple substitutions +# the maps used (%simple_map and %things_map) MUST be aware of this +# watch out for regexps, / and escaped characters! +$subst_code = ''; +foreach (keys(%simple_map)) { + ($re = $_) =~ s/(\W)/\\$1/g; # protect regexp chars + $subst_code .= "s/\\\@$re/$simple_map{$_}/g;\n"; +} +foreach (keys(%things_map)) { + $subst_code .= "s/\\\@$_\\{\\}/$things_map{$_}/g;\n"; +} +if ($use_acc) { + # accentuated characters + foreach (keys(%accent_map)) { + if ($_ eq "`") { + $subst_code .= "s/$;3"; + } elsif ($_ eq "'") { + $subst_code .= "s/$;4"; + } else { + $subst_code .= "s/\\\@\\$_"; + } + $subst_code .= "([a-z])/&\${1}$accent_map{$_};/gi;\n"; + } +} +eval("sub simple_substitutions { $subst_code }"); + +&init_input; +INPUT_LINE: while ($_ = &next_line) { + # + # remove \input on the first lines only + # + if ($first_line) { + next if /^\\input/; + $first_line = 0; + } + # non-@ substitutions cf. texinfmt.el + # + # parse texinfo tags + # + $tag = ''; + $end_tag = ''; + if (/^\s*\@end\s+(\w+)\b/) { + $end_tag = $1; + } elsif (/^\s*\@(\w+)\b/) { + $tag = $1; + } + # + # handle @html / @end html + # + if ($in_html) { + if ($end_tag eq 'html') { + $in_html = 0; + } else { + $tag2pro{$in_html} .= $_; + } + next; + } elsif ($tag eq 'html') { + $in_html = $PROTECTTAG . ++$html_num; + push(@lines, $in_html); + next; + } + + # + # try to remove inlined comments + # syntax from tex-mode.el comment-start-skip + # + s/((^|[^\@])(\@\@)*)\@c(omment | |\{|$).*/$1/; + +# Sometimes I use @c right at the end of a line ( to suppress the line feed ) +# s/((^|[^\@])(\@\@)*)\@c(omment)?$/$1/; +# s/((^|[^\@])(\@\@)*)\@c(omment)? .*/$1/; +# s/(.*)\@c{.*?}(.*)/$1$2/; +# s/(.*)\@comment{.*?}(.*)/$1$2/; +# s/^(.*)\@c /$1/; +# s/^(.*)\@comment /$1/; + + ############################################################# + # value substitution before macro expansion, so that + # it works in macro arguments + s/\@value{($VARRE)}/$value{$1}/eg; + + ############################################################# + # macro substitution + while (/\@(\w+)/g) + { + if (exists($macros->{$1})) + { + my $before = $`; + my $name = $1; + my $after = $'; + my @args; + my $args; + if ($after =~ /^\s*{(.*?[^\\])}(.*)/) + { + $args = $1; + $after = $2; + } + elsif (@{$macros->{$name}->{Args}} == 1) + { + $args = $after; + $args =~ s/^\s*//; + $args =~ s/\s*$//; + $after = ''; + } + $args =~ s|\\\\|\\|g; + $args =~ s|\\{|{|g; + $args =~ s|\\}|}|g; + if (@{$macros->{$name}->{Args}} > 1) + { + $args =~ s/(^|[^\\]),/$1$;/g ; + $args =~ s|\\,|,|g; + @args = split(/$;\s*/, $args) if (@{$macros->{$name}->{Args}} > 1); + } + else + { + $args =~ s|\\,|,|g; + @args = ($args); + } + my $macrobody = $macros->{$name}->{Body}; + for ($i=0; $i<=$#args; $i++) + { + $macrobody =~ s|\\$macros->{$name}->{Args}->[$i]\\|$args[$i]|g; + } + $macrobody =~ s|\\\\|\\|g; + $_ = $before . $macrobody . $after; + unshift @input_spool, map {$_ = $_."\n"} split(/\n/, $_); + next INPUT_LINE; + } + } # + + + # + # try to skip the line + # + if ($end_tag) { + $in_titlepage = 0 if $end_tag eq 'titlepage'; + next if $to_skip{"end $end_tag"}; + } elsif ($tag) { + $in_titlepage = 1 if $tag eq 'titlepage'; + next if $to_skip{$tag}; + last if $tag eq 'bye'; + } + if ($in_top) { + # parsing the top node + if ($tag eq 'node' || + ($sec2level{$tag} && $tag !~ /unnumbered/ && $tag !~ /heading/)) + { + # no more in top + $in_top = 0; + push(@lines, $TOPEND); + } + } + unless ($in_pre) { + s/``/\"/g; + s/''/\"/g; + s/([\w ])---([\w ])/$1--$2/g; + } + # + # analyze the tag + # + if ($tag) { + # skip lines + &skip_until($tag), next if $tag eq 'ignore'; + &skip_until($tag), next if $tag eq 'ifnothtml'; + if ($tag eq 'ifinfo') + { + &skip_until($tag), next unless $T2H_EXPAND eq 'info'; + } + if ($tag eq 'iftex') + { + &skip_until($tag), next unless $T2H_EXPAND eq 'tex'; + } + if ($tag eq 'tex') + { + # add to latex2html file + if ($T2H_EXPAND eq 'tex' && $T2H_L2H && ! $in_pre) + { + # add space to the end -- tex(i2dvi) does this, as well + push(@lines, &l2h_ToLatex(&string_until($tag) . " ")); + } + else + { + &skip_until($tag); + } + next; + } + if ($tag eq 'titlepage') + { + next; + } + # handle special tables + if ($tag =~ /^(|f|v|multi)table$/) { + $table_type = $1; + $tag = 'table'; + } + # special cases + if ($tag eq 'top' || ($tag eq 'node' && /^\@node\s+top\s*,/i)) { + $in_top = 1; + $has_top = 1; + $has_top_command = 1 if $tag eq 'top'; + @lines = (); # ignore all lines before top (title page garbage) + next; + } elsif ($tag eq 'node') { + if ($in_top) + { + $in_top = 0; + push(@lines, $TOPEND); + } + warn "$ERROR Bad node line: $_" unless $_ =~ /^\@node\s$NODESRE$/o; + # request of "Richard Y. Kim" + s/^\@node\s+//; + $_ = &protect_html($_); # if node contains '&' for instance + ($node, $node_next, $node_prev, $node_up) = split(/,/); + &normalise_node($node); + &normalise_node($node_next); + &normalise_node($node_prev); + &normalise_node($node_up); + $node =~ /\"/ ? + push @lines, &html_debug("\n", __LINE__) : + push @lines, &html_debug("\n", __LINE__); + next; + } elsif ($tag eq 'include') { + if (/^\@include\s+($FILERE)\s*$/o) { + $file = LocateIncludeFile($1); + if ($file && -e $file) { + &open($file); + print "# including $file\n" if $T2H_VERBOSE; + } else { + warn "$ERROR Can't find $1, skipping"; + } + } else { + warn "$ERROR Bad include line: $_"; + } + next; + } elsif ($tag eq 'ifclear') { + if (/^\@ifclear\s+($VARRE)\s*$/o) { + next unless defined($value{$1}); + &skip_until($tag); + } else { + warn "$ERROR Bad ifclear line: $_"; + } + next; + } elsif ($tag eq 'ifset') { + if (/^\@ifset\s+($VARRE)\s*$/o) { + next if defined($value{$1}); + &skip_until($tag); + } else { + warn "$ERROR Bad ifset line: $_"; + } + next; + } elsif ($tag eq 'menu') { + unless ($T2H_SHOW_MENU) { + &skip_until($tag); + next; + } + &html_push_if($tag); + push(@lines, &html_debug('', __LINE__)); + } elsif ($format_map{$tag}) { + $in_pre = 1 if $format_map{$tag} eq 'PRE'; + &html_push_if($format_map{$tag}); + push(@lines, &html_debug('', __LINE__)); + $in_list++ if $format_map{$tag} eq 'UL' || $format_map{$tag} eq 'OL' ; +# push(@lines, &debug("

    \n", __LINE__)) +# if $tag =~ /example/i; + # sunshine@sunshineco.com: 
    bla
    looks better than + # 
    \nbla
    (at least on NeXTstep browser + push(@lines, &debug("<$format_map{$tag}>" . + ($in_pre ? '' : "\n"), __LINE__)); + next; + } + elsif (exists $complex_format_map->{$tag}) + { + my $start = eval $complex_format_map->{$tag}->[0]; + if ($@) + { + print "$ERROR: eval of complex_format_map->{$tag}->[0] $complex_format_map->{$tag}->[0]: $@"; + $start = '
    '
+	  }
+	  $in_pre = 1 if $start =~ /
    \n", __LINE__));
+		    &html_push_if('TABLE');
+		} else {
+		    push(@lines, &debug("
    \n", __LINE__));
+		    &html_push_if('DL');
+		}
+		push(@lines, &html_debug('', __LINE__));
+	    } else {
+		warn "$ERROR Bad table line: $_";
+	    }
+	    next;
+	} 
+	elsif ($tag eq 'synindex' || $tag eq 'syncodeindex') 
+	{
+	  if (/^\@$tag\s+(\w+)\s+(\w+)\s*$/) 
+	  {
+	    my $from = $1;
+	    my $to = $2;
+	    my $prefix_from = IndexName2Prefix($from);
+	    my $prefix_to = IndexName2Prefix($to);
+
+	    warn("$ERROR unknown from index name $from ind syn*index line: $_"), next
+	      unless $prefix_from;
+	    warn("$ERROR unknown to index name $to ind syn*index line: $_"), next
+	      unless $prefix_to;
+
+	    if ($tag eq 'syncodeindex')
+	    {
+	      $index_properties->{$prefix_to}->{'from_code'}->{$prefix_from} = 1;
+	    }
+	    else
+	    {
+	       $index_properties->{$prefix_to}->{'from'}->{$prefix_from} = 1;
+	    }
+	  } 
+	  else 
+	  {
+	    warn "$ERROR Bad syn*index line: $_";
+	  }
+	  next;
+	} 
+	elsif ($tag eq 'defindex' || $tag eq 'defcodeindex') 
+	{
+	  if (/^\@$tag\s+(\w+)\s*$/) 
+	  {
+	    my $name = $1;
+	    $index_properties->{$name}->{name} = $name;
+	    $index_properties->{$name}->{code} = 1 if $tag eq 'defcodeindex';
+	  } 
+	  else 
+	  {
+	    warn "$ERROR Bad defindex line: $_";
+	  }
+	  next;
+	}
+	elsif (/^\@printindex/)
+	{
+	  push (@lines, "$_");
+	  next;
+	}
+	elsif ($tag eq 'sp') {
+	    push(@lines, &debug("
    \n", __LINE__));
+	    next;
+	} elsif ($tag eq 'center') {
+	    push(@lines, &debug("
    \n", __LINE__));
+	    s/\@center//;
+	} elsif ($tag eq 'setref') {
+	    &protect_html; # if setref contains '&' for instance
+	    if (/^\@$tag\s*{($NODERE)}\s*$/) {
+		$setref = $1;
+		$setref =~ s/\s+/ /g; # normalize
+		$setref =~ s/ $//;
+		$node2sec{$setref} = $name;
+		$sec2node{$name} = $setref;
+		$node2href{$setref} = "$docu_doc#$docid";
+	    } else {
+		warn "$ERROR Bad setref line: $_";
+	    }
+	    next;
+	} elsif ($tag eq 'lowersections') {
+	    local ($sec, $level);
+	    while (($sec, $level) = each %sec2level) {
+		$sec2level{$sec} = $level + 1;
+	    }
+	    next;
+	} elsif ($tag eq 'raisesections') {
+	    local ($sec, $level);
+	    while (($sec, $level) = each %sec2level) {
+		$sec2level{$sec} = $level - 1;
+	    }
+	    next;
+	}
+	elsif ($tag eq 'macro' || $tag eq 'rmacro')
+	{
+	  if (/^\@$tag\s*(\w+)\s*(.*)/)
+	  {
+	    my $name = $1;
+	    my @args;
+	    @args = split(/\s*,\s*/ , $1)
+	      if ($2 =~ /^\s*{(.*)}\s*/);
+	    
+	    $macros->{$name}->{Args} = \@args;
+	    $macros->{$name}->{Body} = '';
+	    while (($_ = &next_line) && $_ !~ /\@end $tag/)
+	    {
+	      $macros->{$name}->{Body} .= $_;
+	    }
+	    die "ERROR: No closing '\@end $tag' found for macro definition of '$name'\n"
+	      unless (/\@end $tag/);
+	    chomp $macros->{$name}->{Body};
+	  }
+	  else
+	  {
+	    warn "$ERROR: Bad macro defintion $_"
+	  }
+	  next;
+	}
+	elsif ($tag eq 'unmacro')
+	{
+	  delete $macros->{$1} if (/^\@unmacro\s*(\w+)/);
+	  next;
+	}
+	elsif ($tag eq 'documentlanguage')
+	{
+	  SetDocumentLanguage($1) if (!$T2H_LANG && /documentlanguage\s*(\w+)/);
+	}
+	elsif (defined($def_map{$tag})) {
+	    if ($def_map{$tag}) {
+		s/^\@$tag\s+//;
+		$tag = $def_map{$tag};
+		$_ = "\@$tag $_";
+		$tag =~ s/\s.*//;
+	    }
+	} elsif (defined($user_sub{$tag})) {
+	    s/^\@$tag\s+//;
+	    $sub = $user_sub{$tag};
+	    print "# user $tag = $sub, arg: $_" if $T2H_DEBUG & $DEBUG_USER;
+	    if (defined(&$sub)) {
+		chop($_);
+		&$sub($_);
+	    } else {
+		warn "$ERROR Bad user sub for $tag: $sub\n";
+	    }
+	    next;
+	  } 
+	if (defined($def_map{$tag})) {
+	    s/^\@$tag\s+//;
+	    if ($tag =~ /x$/) {
+		# extra definition line
+		$tag = $`;
+		$is_extra = 1;
+	    } else {
+		$is_extra = 0;
+	    }
+	    while (/\{([^\{\}]*)\}/) {
+		# this is a {} construct
+		($before, $contents, $after) = ($`, $1, $');
+		# protect spaces
+		$contents =~ s/\s+/$;9/g;
+		# restore $_ protecting {}
+		$_ = "$before$;7$contents$;8$after";
+	    }
+	    @args = split(/\s+/, &protect_html($_));
+	    foreach (@args) {
+		s/$;9/ /g;	# unprotect spaces
+		s/$;7/\{/g;	# ... {
+		s/$;8/\}/g;	# ... }
+	    }
+	    $type = shift(@args);
+	    $type =~ s/^\{(.*)\}$/$1/;
+	    print "# def ($tag): {$type} ", join(', ', @args), "\n"
+		if $T2H_DEBUG & $DEBUG_DEF;
+	    $type .= ':'; # it's nicer like this
+	    my $name = shift(@args);
+	    $name =~ s/^\{(.*)\}$/$1/;
+	    if ($is_extra) {
+		$_ = &debug("
    ", __LINE__);
+	    } else {
+		$_ = &debug("
    \n
    ", __LINE__);
+	    }
+	    if ($tag eq 'deffn' || $tag eq 'defvr' || $tag eq 'deftp') {
+		$_ .= "$type $name";
+		$_ .= " @args" if @args;
+	    } elsif ($tag eq 'deftypefn' || $tag eq 'deftypevr'
+		     || $tag eq 'defcv' || $tag eq 'defop') {
+		$ftype = $name;
+		$name = shift(@args);
+		$name =~ s/^\{(.*)\}$/$1/;
+		$_ .= "$type $ftype $name";
+		$_ .= " @args" if @args;
+	    } else {
+		warn "$ERROR Unknown definition type: $tag\n";
+		$_ .= "$type $name";
+		$_ .= " @args" if @args;
+	    }
+ 	    $_ .= &debug("\n
    ", __LINE__);
+	    $name = &unprotect_html($name);
+	    if ($tag eq 'deffn' || $tag eq 'deftypefn') {
+	      EnterIndexEntry('f', $name, $docu_doc, $section, \@lines);
+#		unshift(@input_spool, "\@findex $name\n");
+	    } elsif ($tag eq 'defop') {
+	      EnterIndexEntry('f', "$name on $ftype", $docu_doc, $section, \@lines);
+#		unshift(@input_spool, "\@findex $name on $ftype\n");
+	    } elsif ($tag eq 'defvr' || $tag eq 'deftypevr' || $tag eq 'defcv') {
+	      EnterIndexEntry('v', $name, $docu_doc, $section, \@lines);
+#		unshift(@input_spool, "\@vindex $name\n");
+	    } else {
+	      EnterIndexEntry('t', $name, $docu_doc, $section, \@lines);
+#		unshift(@input_spool, "\@tindex $name\n");
+	    }
+	    $dont_html = 1;
+	}
+    } elsif ($end_tag) {
+	if ($format_map{$end_tag}) {
+	    $in_pre = 0 if $format_map{$end_tag} eq 'PRE';
+	    $in_list-- if $format_map{$end_tag} eq 'UL' || $format_map{$end_tag} eq 'OL' ;
+	    &html_pop_if('P');
+	    &html_pop_if('LI');
+	    &html_pop_if();
+	    push(@lines, &debug("\n", __LINE__));
+	    push(@lines, &html_debug('', __LINE__));
+	}
+	elsif (exists $complex_format_map->{$end_tag})
+	{
+	  my $end = eval $complex_format_map->{$end_tag}->[1];
+	  if ($@)
+	  {
+	    print "$ERROR: eval of complex_format_map->{$end_tag}->[1] $complex_format_map->{$end_tag}->[0]: $@";
+	    $end = '
    '
+	  }
+	  $in_pre = 0 if $end =~ m|
    |; + push(@lines, html_debug($end, __LINE__)); + } elsif ($end_tag =~ /^(|f|v|multi)table$/) { + unless (@tables) { + warn "$ERROR \@end $end_tag without \@*table\n"; + next; + } + &html_pop_if('P'); + ($table_type, $in_table) = split($;, shift(@tables)); + unless ($1 eq $table_type) { + warn "$ERROR \@end $end_tag without matching \@$end_tag\n"; + next; + } + if ($table_type eq "multi") { + push(@lines, "
    \n"); + &html_pop_if('TR'); + } else { + push(@lines, "\n"); + &html_pop_if('DD'); + } + &html_pop_if(); + if (@tables) { + ($table_type, $in_table) = split($;, $tables[0]); + } else { + $in_table = 0; + } + } elsif (defined($def_map{$end_tag})) { + push(@lines, &debug("\n", __LINE__)); + } elsif ($end_tag eq 'menu') { + &html_pop_if(); + push(@lines, $_); # must keep it for pass 2 + } + next; + } + ############################################################# + # anchor insertion + while (/\@anchor\s*\{(.*?)\}/) + { + $_ = $`.$'; + my $anchor = $1; + $anchor = &normalise_node($anchor); + push @lines, &html_debug("\n"); + $node2href{$anchor} = "$docu_doc#$anchor"; + next INPUT_LINE if $_ =~ /^\s*$/; + } + + ############################################################# + # index entry generation, after value substitutions + if (/^\@(\w+?)index\s+/) + { + EnterIndexEntry($1, $', $docu_doc, $section, \@lines); + next; + } + # + # protect texi and HTML things + &protect_texi; + $_ = &protect_html($_) unless $dont_html; + $dont_html = 0; + # substitution (unsupported things) + s/^\@exdent\s+//g; + s/\@noindent\s+//g; + s/\@refill\s+//g; + # other substitutions + &simple_substitutions; + s/\@footnote\{/\@footnote$docu_doc\{/g; # mark footnotes, cf. pass 4 + # + # analyze the tag again + # + if ($tag) { + if (defined($sec2level{$tag}) && $sec2level{$tag} > 0) { + if (/^\@$tag\s+(.+)$/) { + $name = $1; + $name = &normalise_node($name); + $level = $sec2level{$tag}; + # check for index +# $first_index_chapter = $name + $first_index_chapter = $node + if ($level == 1 && !$first_index_chapter && + $name =~ /index/i); +if ($level == 1 && $name =~ /index/i) { + print "# at level 1 found '" . $name . "' as matching index name (node = '" . $node . "')\n"; + print "# first index chapter = '" . $first_index_chapter . "' \n"; +} + if ($in_top && /heading/){ + $T2H_HAS_TOP_HEADING = 1; + $_ = &debug("$name\n", __LINE__); + &html_push_if('body'); + print "# top heading, section $name, level $level\n" + if $T2H_DEBUG & $DEBUG_TOC; + } + else + { + unless (/^\@\w*heading/) + { + unless (/^\@unnumbered/) + { + my $number = &update_sec_num($tag, $level); + $name = $number. ' ' . $name if $T2H_NUMBER_SECTIONS; + $sec2number{$name} = $number; + $number2sec{$number} = $name; + } + if (defined($toplevel)) + { + push @lines, ($level==$toplevel ? $CHAPTEREND : $SECTIONEND); + } + else + { + # first time we see a "section" + unless ($level == 1) + { + warn "$WARN The first section found is not of level 1: $_"; + } + $toplevel = $level; + } + push(@sections, $name); + next_doc() if ($T2H_SPLIT eq 'section' || + $T2H_SPLIT && $level == $toplevel); + } + $sec_num++; + $docid = "SEC$sec_num"; + $tocid = (/^\@\w*heading/ ? undef : "TOC$sec_num"); + # check biblio and glossary + $in_bibliography = ($name =~ /^([A-Z]|\d+)?(\.\d+)*\s*bibliography$/i); + $in_glossary = ($name =~ /^([A-Z]|\d+)?(\.\d+)*\s*glossary$/i); + # check node + if ($node) + { + warn "$ERROR Duplicate node found: $node\n" + if ($node2sec{$node}); + } + else + { + $name .= ' ' while ($node2sec{$name}); + $node = $name; + } + $name .= ' ' while ($sec2node{$name}); + $section = $name; + $node2sec{$node} = $name; + $sec2node{$name} = $node; + $node2href{$node} = "$docu_doc#$docid"; +print "# set node2href for '" . $node . "' (" . $name . ") to '" . $node2href{$node} . "'\n" + if ($node =~ /index/i); + $node2next{$node} = $node_next; + $node2prev{$node} = $node_prev; + $node2up{$node} = $node_up; + print "# node $node, section $name, level $level\n" + if $T2H_DEBUG & $DEBUG_TOC; + + $node = ''; + $node_next = ''; + $node_prev = ''; + $node_next = ''; + if ($tocid) + { + # update TOC + while ($level > $curlevel) { + $curlevel++; + push(@toc_lines, "
      \n"); + } + while ($level < $curlevel) { + $curlevel--; + push(@toc_lines, "
    \n"); + } + $_ = &t2h_anchor($tocid, "$docu_doc#$docid", $name, 1); + $_ = &substitute_style($_); + push(@stoc_lines, "$_
    \n") if ($level == 1); + if ($T2H_NUMBER_SECTIONS) + { + push(@toc_lines, $_ . "
    \n") + } + else + { + push(@toc_lines, "
  • " . $_ ."
    • "); + } + } + else + { + push(@lines, &html_debug("\n", + __LINE__)); + } + # update DOC + push(@lines, &html_debug('', __LINE__)); + &html_reset; + $_ = " $name \n\n"; + $_ = &debug($_, __LINE__); + push(@lines, &html_debug('', __LINE__)); + } + # update DOC + foreach $line (split(/\n+/, $_)) { + push(@lines, "$line\n"); + } + next; + } else { + warn "$ERROR Bad section line: $_"; + } + } else { + # track variables + $value{$1} = Unprotect_texi($2), next if /^\@set\s+($VARRE)\s+(.*)$/o; + delete $value{$1}, next if /^\@clear\s+($VARRE)\s*$/o; + # store things + $value{'_shorttitle'} = Unprotect_texi($1), next if /^\@shorttitle\s+(.*)$/; + $value{'_setfilename'} = Unprotect_texi($1), next if /^\@setfilename\s+(.*)$/; + $value{'_settitle'} = Unprotect_texi($1), next if /^\@settitle\s+(.*)$/; + $value{'_author'} .= Unprotect_texi($1)."\n", next if /^\@author\s+(.*)$/; + $value{'_subtitle'} .= Unprotect_texi($1)."\n", next if /^\@subtitle\s+(.*)$/; + $value{'_title'} .= Unprotect_texi($1)."\n", next if /^\@title\s+(.*)$/; + + # list item + if (/^\s*\@itemx?\s+/) { + $what = $'; + $what =~ s/\s+$//; + if ($in_bibliography && $use_bibliography) { + if ($what =~ /^$BIBRE$/o) { + $id = 'BIB' . ++$bib_num; + $bib2href{$what} = "$docu_doc#$id"; + print "# found bibliography for '$what' id $id\n" + if $T2H_DEBUG & $DEBUG_BIB; + $what = &t2h_anchor($id, '', $what); + } + } elsif ($in_glossary && $T2H_USE_GLOSSARY) { + $id = 'GLOSS' . ++$gloss_num; + $entry = $what; + $entry =~ tr/A-Z/a-z/ unless $entry =~ /^[A-Z\s]+$/; + $gloss2href{$entry} = "$docu_doc#$id"; + print "# found glossary for '$entry' id $id\n" + if $T2H_DEBUG & $DEBUG_GLOSS; + $what = &t2h_anchor($id, '', $what); + } + elsif ($in_table && ($table_type eq 'f' || $table_type eq 'v')) + { + EnterIndexEntry($table_type, $what, $docu_doc, $section, \@lines); + } + &html_pop_if('P'); + if ($html_element eq 'DL' || $html_element eq 'DD') { + if ($things_map{$in_table} && !$what) { + # special case to allow @table @bullet for instance + push(@lines, &debug("
    $things_map{$in_table}\n", __LINE__)); + } else { + push(@lines, &debug("
    \@$in_table\{$what\}\n", __LINE__)); + } + push(@lines, "
    "); + &html_push('DD') unless $html_element eq 'DD'; + if ($table_type) { # add also an index + unshift(@input_spool, "\@${table_type}index $what\n"); + } + } elsif ($html_element eq 'TABLE') { + push(@lines, &debug("
    $what
    $what$1
    Jump to:   '; + + for $page ($first_page, @$Pages) + { + for $letter (@{$page->{Letters}}) + { + $l = t2h_anchor('', "$page->{href}#${name}_$letter", "$letter", + 0, 'style="text-decoration:none"') . "\n   \n"; + + if ($letter =~ /^[A-Za-z]/) + { + $l2 .= $l; + } + else + { + $l1 .= $l; + } + } + } + $summary .= $l1 . "
    \n" if ($l1); + $summary .= $l2 . '

    '; + return $summary; +} + +sub PrintIndexPage +{ + my $lines = shift; + my $summary = shift; + my $page = shift; + my $name = shift; + + push @$lines, $summary; + + push @$lines , <

    + + + +EOT + + for $letter (@{$page->{Letters}}) + { + push @$lines, "\n"; + for $entry (@{$page->{EntriesByLetter}->{$letter}}) + { + push @$lines, + "\n"; + } + push @$lines, "\n"; + } + push @$lines, "
    Index Entry Section
    $letter
    " . + t2h_anchor('', $entry->{href}, $entry->{html_key}) . + "" . + t2h_anchor('', sec_href($entry->{section}), clean_name($entry->{section})) . + "

    "; + push @$lines, $summary; +} + +sub PrintIndex +{ + my $lines = shift; + my $name = shift; + my $section = shift; + $section = 'Top' unless $section; + my $prefix = IndexName2Prefix($name); + + warn ("$ERROR printindex: bad index name: $name"), return + unless $prefix; + + if ($index_properties->{$prefix}->{code}) + { + $index_properties->{$prefix}->{from_code}->{$prefix} = 1; + } + else + { + $index_properties->{$prefix}->{from}->{$prefix}= 1; + } + + my $Entries = GetIndexEntries($index_properties->{$prefix}->{from}, + $index_properties->{$prefix}->{from_code}); + return unless %$Entries; + + if ($T2H_IDX_SUMMARY) + { + my $key; + open(FHIDX, ">$docu_rdir$docu_name" . "_$name.idx") + || die "Can't open > $docu_rdir$docu_name" . "_$name.idx for writing: $!\n"; + print "# writing $name index summary in $docu_rdir$docu_name" . "_$name.idx...\n" if $T2H_VERBOSE; + + for $key (sort keys %$Entries) + { + print FHIDX "$key\t$Entries->{$key}->{href}\n"; + } + } + + my $Pages = GetIndexPages($Entries); + my $page; + my $first_page = shift @$Pages; + my $sec_name = $section; + # remove section number + $sec_name =~ s/.*? // if $sec_name =~ /^([A-Z]|\d+)\./; + + ($first_page->{href} = sec_href($section)) =~ s/\#.*$//; + # Update tree structure of document + if (@$Pages) + { + my $sec; + my @after; + + while (@sections && $sections[$#sections] ne $section) + { + unshift @after, pop @sections; + } + + for $page (@$Pages) + { + my $node = ($page->{First} ne $page->{Last} ? + "$sec_name: $page->{First} -- $page->{Last}" : + "$sec_name: $page->{First}"); + push @sections, $node; + $node2sec{$node} = $node; + $sec2node{$node} = $node; + $node2up{$node} = $section; + $page->{href} = next_doc(); + $page->{name} = $node; + $node2href{$node} = $page->{href}; + if ($prev_node) + { + $node2next{$prev_node} = $node; + $node2prev{$node} = $prev_node; + } + $prev_node = $node; + } + push @sections, @after; + } + + my $summary = GetIndexSummary($first_page, $Pages, $name); + PrintIndexPage($lines, $summary, $first_page, $name); + for $page (@$Pages) + { + push @$lines, ($T2H_SPLIT eq 'chapter' ? $CHAPTEREND : $SECTIONEND); + push @$lines, "

    $page->{name}

    \n"; + PrintIndexPage($lines, $summary, $page, $name); + } +} + + +#+++############################################################################ +# # +# Pass 2/3: handle style, menu, index, cross-reference # +# # +#---############################################################################ + +@lines2 = (); # whole document (2nd pass) +@lines3 = (); # whole document (3rd pass) +$in_menu = 0; # am I inside a menu + +while (@lines) { + $_ = shift(@lines); + # + # special case (protected sections) + # + if (/^$PROTECTTAG/o) { + push(@lines2, $_); + next; + } + # + # menu + # + if (/^\@menu\b/) + { + $in_menu = 1; + $in_menu_listing = 1; + push(@lines2, &debug("
    \n", __LINE__)); + next; + } + if (/^\@end\s+menu\b/) + { + if ($in_menu_listing) + { + push(@lines2, &debug("
    \n", __LINE__)); + } + else + { + push(@lines2, &debug("\n", __LINE__)); + } + $in_menu = 0; + $in_menu_listing = 0; + next; + } + if ($in_menu) + { + my ($node, $name, $descr); + if (/^\*\s+($NODERE)::/o) + { + $node = $1; + $descr = $'; + } + elsif (/^\*\s+(.+):\s+([^\t,\.\n]+)[\t,\.\n]/) + { + $name = $1; + $node = $2; + $descr = $'; + } + elsif (/^\*/) + { + warn "$ERROR Bad menu line: $_"; + } + else + { + if ($in_menu_listing) + { + $in_menu_listing = 0; + push(@lines2, &debug("
    \n", __LINE__)); + } + # should be like verbatim -- preseve spaces, etc + s/ /\ /g; + $_ .= "
    \n"; + push(@lines2, $_); + } + if ($node) + { + if (! $in_menu_listing) + { + $in_menu_listing = 1; + push(@lines2, &debug("\n", __LINE__)); + } + # look for continuation + while ($lines[0] =~ /^\s+\w+/) + { + $descr .= shift(@lines); + } + &menu_entry($node, $name, $descr); + } + next; + } + # + # printindex + # + PrintIndex(\@lines2, $2, $1), next + if (/^\@printindex\s+(\w+)/); + # + # simple style substitutions + # + $_ = &substitute_style($_); + # + # xref + # + while (/\@(x|px|info|)ref{([^{}]+)(}?)/) { + # note: Texinfo may accept other characters + ($type, $nodes, $full) = ($1, $2, $3); + ($before, $after) = ($`, $'); + if (! $full && $after) { + warn "$ERROR Bad xref (no ending } on line): $_"; + $_ = "$before$;0${type}ref\{$nodes$after"; + next; # while xref + } + if ($type eq 'x') { + $type = "$T2H_WORDS->{$T2H_LANG}->{'See'} "; + } elsif ($type eq 'px') { + $type = "$T2H_WORDS->{$T2H_LANG}->{'see'} "; + } elsif ($type eq 'info') { + $type = "$T2H_WORDS->{$T2H_LANG}->{'See'} Info"; + } else { + $type = ''; + } + unless ($full) { + $next = shift(@lines); + $next = &substitute_style($next); + chop($nodes); # remove final newline + if ($next =~ /\}/) { # split on 2 lines + $nodes .= " $`"; + $after = $'; + } else { + $nodes .= " $next"; + $next = shift(@lines); + $next = &substitute_style($next); + chop($nodes); + if ($next =~ /\}/) { # split on 3 lines + $nodes .= " $`"; + $after = $'; + } else { + warn "$ERROR Bad xref (no ending }): $_"; + $_ = "$before$;0xref\{$nodes$after"; + unshift(@lines, $next); + next; # while xref + } + } + } + $nodes =~ s/\s+/ /g; # remove useless spaces + @args = split(/\s*,\s*/, $nodes); + $node = $args[0]; # the node is always the first arg + $node = &normalise_node($node); + $sec = $args[2] || $args[1] || $node2sec{$node}; + $href = $node2href{$node}; + if (@args == 5) { # reference to another manual + $sec = $args[2] || $node; + $man = $args[4] || $args[3]; + $_ = "${before}${type}$T2H_WORDS->{$T2H_LANG}->{'section'} `$sec' in \@cite{$man}$after"; + } elsif ($type =~ /Info/) { # inforef + warn "$ERROR Wrong number of arguments: $_" unless @args == 3; + ($nn, $_, $in) = @args; + $_ = "${before}${type} file `$in', node `$nn'$after"; + } elsif ($sec && $href && ! $T2H_SHORT_REF) { + $_ = "${before}${type}"; + $_ .= "$T2H_WORDS->{$T2H_LANG}->{'section'} " if ${type}; + $_ .= &t2h_anchor('', $href, $sec) . $after; + } + elsif ($href) + { + $_ = "${before}${type} " . + &t2h_anchor('', $href, $args[2] || $args[1] || $node) . + $after; + } + else { + warn "$ERROR Undefined node ($node): $_"; + $_ = "$before$;0xref{$nodes}$after"; + } + } + + # replace images + s[\@image\s*{(.+?)}] + { + my @args = split (/\s*,\s*/, $1); + my $base = $args[0]; + my $image = + LocateIncludeFile("$base.png") || + LocateIncludeFile("$base.jpg") || + LocateIncludeFile("$base.gif"); + warn "$ERROR no image file for $base: $_" unless ($image && -e $image); + "\"$base\""; + ($T2H_CENTER_IMAGE ? + "
    \"$base\"
    " : + "\"$base\""); + }eg; + + # + # try to guess bibliography references or glossary terms + # + unless (/^/) { + $done .= $pre . &t2h_anchor('', $href, $what); + } else { + $done .= "$pre$what"; + } + $_ = $post; + } + $_ = $done . $_; + } + if ($T2H_USE_GLOSSARY) { + $done = ''; + while (/\b\w+\b/) { + ($pre, $what, $post) = ($`, $&, $'); + $entry = $what; + $entry =~ tr/A-Z/a-z/ unless $entry =~ /^[A-Z\s]+$/; + $href = $gloss2href{$entry}; + if (defined($href) && $post !~ /^[^<]*<\/A>/) { + $done .= $pre . &t2h_anchor('', $href, $what); + } else { + $done .= "$pre$what"; + } + $_ = $post; + } + $_ = $done . $_; + } + } + # otherwise + push(@lines2, $_); +} +print "# end of pass 2\n" if $T2H_VERBOSE; + +# +# split style substitutions +# +while (@lines2) { + $_ = shift(@lines2); + # + # special case (protected sections) + # + if (/^$PROTECTTAG/o) { + push(@lines3, $_); + next; + } + # + # split style substitutions + # + $old = ''; + while ($old ne $_) { + $old = $_; + if (/\@(\w+)\{/) { + ($before, $style, $after) = ($`, $1, $'); + if (defined($style_map{$style})) { + $_ = $after; + $text = ''; + $after = ''; + $failed = 1; + while (@lines2) { + if (/\}/) { + $text .= $`; + $after = $'; + $failed = 0; + last; + } else { + $text .= $_; + $_ = shift(@lines2); + } + } + if ($failed) { + die "* Bad syntax (\@$style) after: $before\n"; + } else { + $text = &apply_style($style, $text); + $_ = "$before$text$after"; + } + } + } + } + # otherwise + push(@lines3, $_); +} +print "# end of pass 3\n" if $T2H_VERBOSE; + +#+++############################################################################ +# # +# Pass 4: foot notes, final cleanup # +# # +#---############################################################################ + +@foot_lines = (); # footnotes +@doc_lines = (); # final document +$end_of_para = 0; # true if last line is

    + +while (@lines3) { + $_ = shift(@lines3); + # + # special case (protected sections) + # + if (/^$PROTECTTAG/o) { + push(@doc_lines, $_); + $end_of_para = 0; + next; + } + # + # footnotes + # + while (/\@footnote([^\{\s]+)\{/) { + ($before, $d, $after) = ($`, $1, $'); + $_ = $after; + $text = ''; + $after = ''; + $failed = 1; + while (@lines3) { + if (/\}/) { + $text .= $`; + $after = $'; + $failed = 0; + last; + } else { + $text .= $_; + $_ = shift(@lines3); + } + } + if ($failed) { + die "* Bad syntax (\@footnote) after: $before\n"; + } else { + $foot_num++; + $docid = "DOCF$foot_num"; + $footid = "FOOT$foot_num"; + $foot = "($foot_num)"; + push(@foot_lines, "

    " . &t2h_anchor($footid, "$d#$docid", $foot) . "

    \n"); + $text = "

    $text" unless $text =~ /^\s*

    /; + push(@foot_lines, "$text\n"); + $_ = $before . &t2h_anchor($docid, "$docu_foot#$footid", $foot) . $after; + } + } + # + # remove unnecessary

    + # + if (/^\s*

    \s*$/) { + next if $end_of_para++; + } else { + $end_of_para = 0; + } + # otherwise + push(@doc_lines, $_); +} + +print "# end of pass 4\n" if $T2H_VERBOSE; + +#+++############################################################################ +# # +# Pass 5: print things # +# # +#---############################################################################ + +$T2H_L2H = &l2h_FinishToLatex if ($T2H_L2H); +$T2H_L2H = &l2h_ToHtml if ($T2H_L2H); +$T2H_L2H = &l2h_InitFromHtml if ($T2H_L2H); + +# fix node2up, node2prev, node2next, if desired +if ($has_top_command) +{ + for $section (keys %sec2number) + { + $node = $sec2node{$section}; + $node2up{$node} = Sec2UpNode($section) unless $node2up{$node}; + $node2prev{$node} = Sec2PrevNode($section) unless $node2prev{$node}; + $node2next{$node} = Sec2NextNode($section) unless $node2next{$node}; + } +} + +# prepare %T2H_THISDOC +$T2H_THISDOC{fulltitle} = $value{'_title'} || $value{'_settitle'} || "Untitled Document"; +$T2H_THISDOC{title} = $value{'_settitle'} || $T2H_THISDOC{fulltitle}; +$T2H_THISDOC{author} = $value{'_author'}; +$T2H_THISDOC{subtitle} = $value{'_subtitle'}; +$T2H_THISDOC{shorttitle} = $value{'_shorttitle'}; +for $key (keys %T2H_THISDOC) +{ + $_ = &substitute_style($T2H_THISDOC{$key}); + &unprotect_texi; + s/\s*$//; + $T2H_THISDOC{$key} = $_; +} + +# if no sections, then simply print document as is +unless (@sections) +{ + print "# Writing content into $docu_top_file \n" if $T2H_VERBOSE; + open(FILE, "> $docu_top_file") + || die "$ERROR: Can't open $docu_top_file for writing: $!\n"; + + &$T2H_print_page_head(\*FILE); + $T2H_THIS_SECTION = \@doc_lines; + t2h_print_lines(\*FILE); + &$T2H_print_foot_navigation(\*FILE); + &$T2H_print_page_foot(\*FILE); + close(FILE); + goto Finish; +} + +# initialize $T2H_HREF, $T2H_NAME +%T2H_HREF = + ( + 'First' , sec_href($sections[0]), + 'Last', sec_href($sections[$#sections]), + 'About', $docu_about. '#SEC_About', + ); + +# prepare TOC, OVERVIEW, TOP +$T2H_TOC = \@toc_lines; +$T2H_OVERVIEW = \@stoc_lines; +if ($has_top) +{ + while (1) + { + $_ = shift @doc_lines; + last if /$TOPEND/; + push @$T2H_TOP, $_; + } + $T2H_HREF{'Top'} = $docu_top . '#SEC_Top'; +} +else +{ + $T2H_HREF{'Top'} = $T2H_HREF{First}; +} + +$node2href{Top} = $T2H_HREF{Top}; +$T2H_HREF{Contents} = $docu_toc.'#SEC_Contents' if @toc_lines; +$T2H_HREF{Overview} = $docu_stoc.'#SEC_OVERVIEW' if @stoc_lines; + +# settle on index +if ($T2H_INDEX_CHAPTER) +{ + $T2H_HREF{Index} = $node2href{normalise_node($T2H_INDEX_CHAPTER)}; + warn "$ERROR T2H_INDEX_CHAPTER '$T2H_INDEX_CHAPTER' not found\n" + unless $T2H_HREF{Index}; +} +if (! $T2H_HREF{Index} && $first_index_chapter) +{ + $T2H_INDEX_CHAPTER = $first_index_chapter; + $T2H_HREF{Index} = $node2href{$T2H_INDEX_CHAPTER}; +print "# Set Index HREF to '" . clean_name($T2H_INDEX_CHAPTER) . "' \n"; +} + +print "# Using '" . clean_name($T2H_INDEX_CHAPTER) . "' as index page\n" + if ($T2H_VERBOSE && $T2H_HREF{Index}); + +print "# Using '" . $T2H_HREF{Index} . "' as index href\n"; + +%T2H_NAME = + ( + 'First', clean_name($sec2node{$sections[0]}), + 'Last', clean_name($sec2node{$sections[$#sections]}), + 'About', $T2H_WORDS->{$T2H_LANG}->{'About_Title'}, + 'Contents', $T2H_WORDS->{$T2H_LANG}->{'ToC_Title'}, + 'Overview', $T2H_WORDS->{$T2H_LANG}->{'Overview_Title'}, + 'Index' , clean_name($T2H_INDEX_CHAPTER), + 'Top', clean_name($T2H_TOP_HEADING || $T2H_THISDOC{'title'} || $T2H_THISDOC{'shorttitle'}), + ); + +############################################################################# +# print frame and frame toc file +# +if ( $T2H_FRAMES ) +{ + open(FILE, "> $docu_frame_file") + || die "$ERROR: Can't open $docu_frame_file for writing: $!\n"; + print "# Creating frame in $docu_frame_file ...\n" if $T2H_VERBOSE; + &$T2H_print_frame(\*FILE); + close(FILE); + + open(FILE, "> $docu_toc_frame_file") + || die "$ERROR: Can't open $docu_toc_frame_file for writing: $!\n"; + print "# Creating toc frame in $docu_frame_file ...\n" if $T2H_VERBOSE; + &$T2H_print_toc_frame(\*FILE); + close(FILE); +} + + +############################################################################# +# print Top +# +open(FILE, "> $docu_top_file") + || die "$ERROR: Can't open $docu_top_file for writing: $!\n"; +&$T2H_print_page_head(\*FILE) unless ($T2H_SPLIT); + +if ($has_top) +{ + print "# Creating Top in $docu_top_file ...\n" if $T2H_VERBOSE; + $T2H_THIS_SECTION = $T2H_TOP; + $T2H_HREF{This} = $T2H_HREF{Top}; + $T2H_NAME{This} = $T2H_NAME{Top}; + &$T2H_print_Top(\*FILE); +} + +close(FILE) if $T2H_SPLIT; + +############################################################################# +# Print sections +# +$T2H_NODE{Forward} = $sec2node{$sections[0]}; +$T2H_NAME{Forward} = &clean_name($sec2node{$sections[0]}); +$T2H_HREF{Forward} = sec_href($sections[0]); +$T2H_NODE{This} = 'Top'; +$T2H_NAME{This} = $T2H_NAME{Top}; +$T2H_HREF{This} = $T2H_HREF{Top}; +if ($T2H_SPLIT) +{ + print "# writing " . scalar(@sections) . + " sections in $docu_rdir$docu_name"."_[1..$doc_num]" + if $T2H_VERBOSE; + $previous = ($T2H_SPLIT eq 'chapter' ? $CHAPTEREND : $SECTIONEND); + undef $FH; + $doc_num = 0; +} +else +{ + print "# writing " . scalar(@sections) . " sections in $docu_top_file ..." + if $T2H_VERBOSE; + $FH = \*FILE; + $previous = ''; +} + +$counter = 0; +# loop through sections +while ($section = shift(@sections)) +{ + if ($T2H_SPLIT && ($T2H_SPLIT eq 'section' || $previous eq $CHAPTEREND)) + { + if ($FH) + { + #close previous page + &$T2H_print_chapter_footer($FH) if $T2H_SPLIT eq 'chapter'; + &$T2H_print_page_foot($FH); + close($FH); + undef $FH; + } + } + $T2H_NAME{Back} = $T2H_NAME{This}; + $T2H_HREF{Back} = $T2H_HREF{This}; + $T2H_NODE{Back} = $T2H_NODE{This}; + $T2H_NAME{This} = $T2H_NAME{Forward}; + $T2H_HREF{This} = $T2H_HREF{Forward}; + $T2H_NODE{This} = $T2H_NODE{Forward}; + if ($sections[0]) + { + $T2H_NODE{Forward} = $sec2node{$sections[0]}; + $T2H_NAME{Forward} = &clean_name($T2H_NODE{Forward}); + $T2H_HREF{Forward} = sec_href($sections[0]); + } + else + { + undef $T2H_HREF{Forward}, $T2H_NODE{Forward}, $T2H_NAME{Forward}; + } + + $node = $node2up{$T2H_NODE{This}}; + $T2H_HREF{Up} = $node2href{$node}; + if ($T2H_HREF{Up} eq $T2H_HREF{This} || ! $T2H_HREF{Up}) + { + $T2H_NAME{Up} = $T2H_NAME{Top}; + $T2H_HREF{Up} = $T2H_HREF{Top}; + $T2H_NODE{Up} = 'Up'; + } + else + { + $T2H_NAME{Up} = &clean_name($node); + $T2H_NODE{Up} = $node; + } + + $node = $T2H_NODE{This}; + $node = $node2prev{$node}; + $T2H_NAME{Prev} = &clean_name($node); + $T2H_HREF{Prev} = $node2href{$node}; + $T2H_NODE{Prev} = $node; + + $node = $T2H_NODE{This}; + if ($node2up{$node} && $node2up{$node} ne 'Top'&& + ($node2prev{$node} eq $T2H_NODE{Back} || ! $node2prev{$node})) + { + $node = $node2up{$node}; + while ($node && $node ne $node2up{$node} && ! $node2prev{$node}) + { + $node = $node2up{$node}; + } + $node = $node2prev{$node} + unless $node2up{$node} eq 'Top' || ! $node2up{$node}; + } + else + { + $node = $node2prev{$node}; + } + $T2H_NAME{FastBack} = &clean_name($node); + $T2H_HREF{FastBack} = $node2href{$node}; + $T2H_NODE{FastBack} = $node; + + $node = $T2H_NODE{This}; + $node = $node2next{$node}; + $T2H_NAME{Next} = &clean_name($node); + $T2H_HREF{Next} = $node2href{$node}; + $T2H_NODE{Next} = $node; + + $node = $T2H_NODE{This}; + if ($node2up{$node} && $node2up{$node} ne 'Top'&& + ($node2next{$node} eq $T2H_NODE{Forward} || ! $node2next{$node})) + { + $node = $node2up{$node}; + while ($node && $node ne $node2up{$node} && ! $node2next{$node}) + { + $node = $node2up{$node}; + } + } + $node = $node2next{$node}; + $T2H_NAME{FastForward} = &clean_name($node); + $T2H_HREF{FastForward} = $node2href{$node}; + $T2H_NODE{FastForward} = $node; + + if (! defined($FH)) + { + my $file = $T2H_HREF{This}; + $file =~ s/\#.*$//; + open(FILE, "> $docu_rdir$file") || + die "$ERROR: Can't open $docu_rdir$file for writing: $!\n"; + $FH = \*FILE; + &$T2H_print_page_head($FH); + t2h_print_label($FH); + &$T2H_print_chapter_header($FH) if $T2H_SPLIT eq 'chapter'; + } + else + { + t2h_print_label($FH); + } + + $T2H_THIS_SECTION = []; + while (@doc_lines) { + $_ = shift(@doc_lines); + last if ($_ eq $SECTIONEND || $_ eq $CHAPTEREND); + push(@$T2H_THIS_SECTION, $_); + } + $previous = $_; + &$T2H_print_section($FH); + + if ($T2H_VERBOSE) + { + $counter++; + print "." if $counter =~ /00$/; + } +} +if ($T2H_SPLIT) +{ + &$T2H_print_chapter_footer($FH) if $T2H_SPLIT eq 'chapter'; + &$T2H_print_page_foot($FH); + close($FH); +} +print "\n" if $T2H_VERBOSE; + +############################################################################# +# Print ToC, Overview, Footnotes +# +undef $T2H_HREF{Prev}; +undef $T2H_HREF{Next}; +undef $T2H_HREF{Back}; +undef $T2H_HREF{Forward}; +undef $T2H_HREF{Up}; + +if (@foot_lines) +{ + print "# writing Footnotes in $docu_foot_file...\n" if $T2H_VERBOSE; + open (FILE, "> $docu_foot_file") || die "$ERROR: Can't open $docu_foot_file for writing: $!\n" + if $T2H_SPLIT; + $T2H_HREF{This} = $docu_foot; + $T2H_NAME{This} = $T2H_WORDS->{$T2H_LANG}->{'Footnotes_Title'}; + $T2H_THIS_SECTION = \@foot_lines; + &$T2H_print_Footnotes(\*FILE); + close(FILE) if $T2H_SPLIT; +} + +if (@toc_lines) +{ + print "# writing Toc in $docu_toc_file...\n" if $T2H_VERBOSE; + open (FILE, "> $docu_toc_file") || die "$ERROR: Can't open $docu_toc_file for writing: $!\n" + if $T2H_SPLIT; + $T2H_HREF{This} = $T2H_HREF{Contents}; + $T2H_NAME{This} = $T2H_NAME{Contents}; + $T2H_THIS_SECTION = \@toc_lines; + &$T2H_print_Toc(\*FILE); + close(FILE) if $T2H_SPLIT; +} + +if (@stoc_lines) +{ + print "# writing Overview in $docu_stoc_file...\n" if $T2H_VERBOSE; + open (FILE, "> $docu_stoc_file") || die "$ERROR: Can't open $docu_stoc_file for writing: $!\n" + if $T2H_SPLIT; + + $T2H_HREF{This} = $T2H_HREF{Overview}; + $T2H_NAME{This} = $T2H_NAME{Overview}; + $T2H_THIS_SECTION = \@stoc_lines; + unshift @$T2H_THIS_SECTION, "

    \n"; + push @$T2H_THIS_SECTION, "\n
    \n"; + &$T2H_print_Overview(\*FILE); + close(FILE) if $T2H_SPLIT; +} + +if ($about_body = &$T2H_about_body()) +{ + print "# writing About in $docu_about_file...\n" if $T2H_VERBOSE; + open (FILE, "> $docu_about_file") || die "$ERROR: Can't open $docu_about_file for writing: $!\n" + if $T2H_SPLIT; + + $T2H_HREF{This} = $T2H_HREF{About}; + $T2H_NAME{This} = $T2H_NAME{About}; + $T2H_THIS_SECTION = [$about_body]; + &$T2H_print_About(\*FILE); + close(FILE) if $T2H_SPLIT; +} + +unless ($T2H_SPLIT) +{ + &$T2H_print_page_foot(\*FILE); + close (FILE); +} + +Finish: +&l2h_FinishFromHtml if ($T2H_L2H); +&l2h_Finish if($T2H_L2H); +print "# that's all folks\n" if $T2H_VERBOSE; + +exit(0); + +#+++############################################################################ +# # +# Low level functions # +# # +#---############################################################################ + +sub LocateIncludeFile +{ + my $file = shift; + my $dir; + + return $file if (-e $file && -r $file); + foreach $dir (@T2H_INCLUDE_DIRS) + { + return "$dir/$file" if (-e "$dir/$file" && -r "$dir/$file"); + } + return undef; +} + +sub clean_name +{ + local ($_); + $_ = &remove_style($_[0]); + &unprotect_texi; + return $_; +} + +sub update_sec_num { + local($name, $level) = @_; + my $ret; + + $level--; # here we start at 0 + if ($name =~ /^appendix/ || defined(@appendix_sec_num)) { + # appendix style + if (defined(@appendix_sec_num)) { + &incr_sec_num($level, @appendix_sec_num); + } else { + @appendix_sec_num = ('A', 0, 0, 0); + } + $ret = join('.', @appendix_sec_num[0..$level]); + } else { + # normal style + if (defined(@normal_sec_num)) + { + &incr_sec_num($level, @normal_sec_num); + } + else + { + @normal_sec_num = (1, 0, 0, 0); + } + $ret = join('.', @normal_sec_num[0..$level]); + } + + $ret .= "." if $level == 0; + return $ret; +} + +sub incr_sec_num { + local($level, $l); + $level = shift(@_); + $_[$level]++; + foreach $l ($level+1 .. 3) { + $_[$l] = 0; + } +} + +sub Sec2UpNode +{ + my $sec = shift; + my $num = $sec2number{$sec}; + + return '' unless $num; + return 'Top' unless $num =~ /\.\d+/; + $num =~ s/\.[^\.]*$//; + $num = $num . '.' unless $num =~ /\./; + return $sec2node{$number2sec{$num}}; +} + +sub Sec2PrevNode +{ + my $sec = shift; + my $num = $sec2number{$sec}; + my ($i, $post); + + if ($num =~ /(\w+)(\.$|$)/) + { + $num = $`; + $i = $1; + $post = $2; + if ($i eq 'A') + { + $i = $normal_sec_num[0]; + } + elsif ($i ne '1') + { + # unfortunately, -- operator is not magical + $i = chr(ord($i) + 1); + } + else + { + return ''; + } + return $sec2node{$number2sec{$num . $i . $post}} + } + return ''; +} + +sub Sec2NextNode +{ + my $sec = shift; + my $num = $sec2number{$sec}; + my $i; + + if ($num =~ /(\w+)(\.$|$)/) + { + $num = $`; + $i = $1; + $post = $2; + if ($post eq '.' && $i eq $normal_sec_num[0]) + { + $i = 'A'; + } + else + { + $i++; + } + return $sec2node{$number2sec{$num . $i . $post}} + } + return ''; +} + +sub check { + local($_, %seen, %context, $before, $match, $after); + + while (<>) { + if (/\@(\*|\.|\:|\@|\{|\})/) { + $seen{$&}++; + $context{$&} .= "> $_" if $T2H_VERBOSE; + $_ = "$`XX$'"; + redo; + } + if (/\@(\w+)/) { + ($before, $match, $after) = ($`, $&, $'); + if ($before =~ /\b[\w-]+$/ && $after =~ /^[\w-.]*\b/) { # e-mail address + $seen{'e-mail address'}++; + $context{'e-mail address'} .= "> $_" if $T2H_VERBOSE; + } else { + $seen{$match}++; + $context{$match} .= "> $_" if $T2H_VERBOSE; + } + $match =~ s/^\@/X/; + $_ = "$before$match$after"; + redo; + } + } + + foreach (sort(keys(%seen))) { + if ($T2H_VERBOSE) { + print "$_\n"; + print $context{$_}; + } else { + print "$_ ($seen{$_})\n"; + } + } +} + +sub open { + local($name) = @_; + + ++$fh_name; + if (open($fh_name, $name)) { + unshift(@fhs, $fh_name); + } else { + warn "$ERROR Can't read file $name: $!\n"; + } +} + +sub init_input { + @fhs = (); # hold the file handles to read + @input_spool = (); # spooled lines to read + $fh_name = 'FH000'; + &open($docu); +} + +sub next_line { + local($fh, $line); + + if (@input_spool) { + $line = shift(@input_spool); + return($line); + } + while (@fhs) { + $fh = $fhs[0]; + $line = <$fh>; + return($line) if $line; + close($fh); + shift(@fhs); + } + return(undef); +} + +# used in pass 1, use &next_line +sub skip_until { + local($tag) = @_; + local($_); + + while ($_ = &next_line) { + return if /^\@end\s+$tag\s*$/; + } + die "* Failed to find '$tag' after: " . $lines[$#lines]; +} + +# used in pass 1 for l2h use &next_line +sub string_until { + local($tag) = @_; + local($_, $string); + + while ($_ = &next_line) { + return $string if /^\@end\s+$tag\s*$/; +# $_ =~ s/hbox/mbox/g; + $string = $string.$_; + } + die "* Failed to find '$tag' after: " . $lines[$#lines]; +} + +# +# HTML stacking to have a better HTML output +# + +sub html_reset { + @html_stack = ('html'); + $html_element = 'body'; +} + +sub html_push { + local($what) = @_; + push(@html_stack, $html_element); + $html_element = $what; +} + +sub html_push_if { + local($what) = @_; + push(@html_stack, $html_element) + if ($html_element && $html_element ne 'P'); + $html_element = $what; +} + +sub html_pop { + $html_element = pop(@html_stack); +} + +sub html_pop_if { + local($elt); + + if (@_) { + foreach $elt (@_) { + if ($elt eq $html_element) { + $html_element = pop(@html_stack) if @html_stack; + last; + } + } + } else { + $html_element = pop(@html_stack) if @html_stack; + } +} + +sub html_debug { + local($what, $line) = @_; + if ($T2H_DEBUG & $DEBUG_HTML) + { + $what = "\n" unless $what; + return("$what") + } + return($what); +} + +# to debug the output... +sub debug { + local($what, $line) = @_; + return("$what") + if $T2H_DEBUG & $DEBUG_HTML; + return($what); +} + +sub SimpleTexi2Html +{ + local $_ = $_[0]; + &protect_texi; + &protect_html; + $_ = substitute_style($_); + $_[0] = $_; +} + +sub normalise_node { + local $_ = $_[0]; + s/\s+/ /g; + s/ $//; + s/^ //; + &protect_texi; + &protect_html; + $_ = substitute_style($_); + $_[0] = $_; +} + +sub menu_entry +{ + my ($node, $name, $descr) = @_; + my ($href, $entry); + + &normalise_node($node); + $href = $node2href{$node}; + if ($href) + { + $descr =~ s/^\s+//; + $descr =~ s/\s*$//; + $descr = SimpleTexi2Html($descr); + if ($T2H_NUMBER_SECTIONS && !$T2H_NODE_NAME_IN_MENU && $node2sec{$node}) + { + $entry = $node2sec{$node}; + $name = ''; + } + else + { + &normalise_node($name); + $entry = ($name && ($name ne $node || ! $T2H_AVOID_MENU_REDUNDANCY) + ? "$name : $node" : $node); + } + + if ($T2H_AVOID_MENU_REDUNDANCY && $descr) + { + my $clean_entry = $entry; + $clean_entry =~ s/^.*? // if ($clean_entry =~ /^([A-Z]|\d+)\.[\d\.]* /); + $clean_entry =~ s/[^\w]//g; + my $clean_descr = $descr; + $clean_descr =~ s/[^\w]//g; + $descr = '' if ($clean_entry eq $clean_descr) + } + push(@lines2,&debug('    \n", __LINE__)); + } + elsif ($node =~ /^\(.*\)\w+/) + { + push(@lines2,&debug('\n", __LINE__)) + } + else + { + warn "$ERROR Undefined node of menu_entry ($node): $_"; + } +} + +sub do_ctrl { "^$_[0]" } + +sub do_email { + local($addr, $text) = split(/,\s*/, $_[0]); + + $text = $addr unless $text; + &t2h_anchor('', "mailto:$addr", $text); +} + +sub do_sc +{ + # l2h does this much better + return &l2h_ToLatex("{\\sc ".&unprotect_html($_[0])."}") if ($T2H_L2H); + return "\U$_[0]\E"; +} + +sub do_math +{ + return &l2h_ToLatex("\$".&unprotect_html($_[0])."\$") if ($T2H_L2H); + return "".$text.""; +} + +sub do_uref { + local($url, $text, $only_text) = split(/,\s*/, $_[0]); + + $text = $only_text if $only_text; + $text = $url unless $text; + &t2h_anchor('', $url, $text); +} + +sub do_url { &t2h_anchor('', $_[0], $_[0]) } + +sub do_acronym +{ + return '' . $_[0] . ''; +} + +sub do_accent +{ + return "&$_[0]acute;" if $_[1] eq 'H'; + return "$_[0]." if $_[1] eq 'dotaccent'; + return "$_[0]*" if $_[1] eq 'ringaccent'; + return "$_[0]".'[' if $_[1] eq 'tieaccent'; + return "$_[0]".'(' if $_[1] eq 'u'; + return "$_[0]_" if $_[1] eq 'ubaraccent'; + return ".$_[0]" if $_[1] eq 'udotaccent'; + return "$_[0]<" if $_[1] eq 'v'; + return "&$_[0]cedil;" if $_[1] eq ','; + return "$_[0]" if $_[1] eq 'dotless'; + return undef; +} + +sub apply_style { + local($texi_style, $text) = @_; + local($style); + + $style = $style_map{$texi_style}; + if (defined($style)) { # known style + if ($style =~ /^\"/) { # add quotes + $style = $'; + $text = "\`$text\'"; + } + if ($style =~ /^\&/) { # custom + $style = $'; + $text = &$style($text, $texi_style); + } elsif ($style) { # good style + $text = "<$style>$text"; + } else { # no style + } + } else { # unknown style + $text = undef; + } + return($text); +} + +# remove Texinfo styles +sub remove_style { + local($_) = @_; + 1 while(s/\@\w+{([^\{\}]+)}/$1/g); + return($_); +} + +sub remove_things +{ + local ($_) = @_; + s|\@(\w+)\{\}|$1|g; + return $_; +} + +sub substitute_style { + local($_) = @_; + local($changed, $done, $style, $text); + + &simple_substitutions; + $changed = 1; + while ($changed) { + $changed = 0; + $done = ''; + while (/\@(\w+){([^\{\}]+)}/ || /\@(,){([^\{\}]+)}/) { + $text = &apply_style($1, $2); + if ($text) { + $_ = "$`$text$'"; + $changed = 1; + } else { + $done .= "$`\@$1"; + $_ = "{$2}$'"; + } + } + $_ = $done . $_; + } + return($_); +} + +sub t2h_anchor { + local($name, $href, $text, $newline, $extra_attribs) = @_; + local($result); + + $result = " + $what =~ s/\&/\&\#38;/g; + $what =~ s/\/\&\#62;/g; + # restore anything in quotes + # this fixes my problem where I had: + # < IMG SRC="leftarrow.gif" ALT="<--" > but what if I wanted < in my ALT text ?? + # maybe byte stuffing or some other technique should be used. + $what =~ s/\"([^\&]+)\&\#60;(.*)\"/"$1<$2"/g; + $what =~ s/\"([^\&]+)\&\#62;(.*)\"/"$1>$2"/g; + $what =~ s/\"([^\&]+)\&\#38;(.*)\"/"$1&$2"/g; + # but recognize some HTML things + $what =~ s/\&\#60;\/A\&\#62;/<\/A>/g; # + $what =~ s/\&\#60;A ([^\&]+)\&\#62;//g; # + $what =~ s/\&\#60;IMG ([^\&]+)\&\#62;//g; # + return($what); +} + +sub unprotect_texi { + s/$;0/\@/go; + s/$;1/\{/go; + s/$;2/\}/go; + s/$;3/\`/go; + s/$;4/\'/go; +} + +sub Unprotect_texi +{ + local $_ = shift; + &unprotect_texi; + return($_); +} + +sub unprotect_html { + local($what) = @_; + $what =~ s/\&\#38;/\&/g; + $what =~ s/\&\#60;/\/g; + return($what); +} + +sub t2h_print_label +{ + my $fh = shift; + my $href = shift || $T2H_HREF{This}; + $href =~ s/.*#(.*)$/$1/; + print $fh qq{\n}; +} + +############################################################################## + + # These next few lines are legal in both Perl and nroff. + +.00 ; # finish .ig + +'di \" finish diversion--previous line must be blank +.nr nl 0-1 \" fake up transition to first page again +.nr % 0 \" start at page 1 +'; __END__ ############# From here on it's a standard manual page ############ +.so /usr/local/man/man1/texi2html.1 diff --git a/variables.c b/variables.c index f8b1d3e21..9f8d2543f 100644 --- a/variables.c +++ b/variables.c @@ -26,7 +26,7 @@ #if defined (qnx) # if defined (qnx6) -# include +# include # else # include # endif /* !qnx6 */ @@ -515,6 +515,7 @@ initialize_shell_variables (env, privmode) { sv_history_control ("HISTCONTROL"); sv_histignore ("HISTIGNORE"); + sv_histtimefmt ("HISTTIMEFORMAT"); } #endif /* HISTORY */ diff --git a/variables.c~ b/variables.c~ index 5fd9d0e99..1e82a7963 100644 --- a/variables.c~ +++ b/variables.c~ @@ -26,7 +26,7 @@ #if defined (qnx) # if defined (qnx6) -# include +# include # else # include # endif /* !qnx6 */ @@ -192,6 +192,8 @@ static SHELL_VAR *get_lineno __P((SHELL_VAR *)); static SHELL_VAR *assign_subshell __P((SHELL_VAR *, char *, arrayind_t)); static SHELL_VAR *get_subshell __P((SHELL_VAR *)); +static SHELL_VAR *get_bashpid __P((SHELL_VAR *)); + #if defined (HISTORY) static SHELL_VAR *get_histcmd __P((SHELL_VAR *)); #endif @@ -1271,6 +1273,22 @@ get_subshell (var) return (var); } +static SHELL_VAR * +get_bashpid (var) + SHELL_VAR *var; +{ + int pid; + char *p; + + pid = getpid (); + p = itos (pid); + + FREE (value_cell (var)); + VSETATTR (var, att_integer|att_readonly); + var_setvalue (var, p); + return (var); +} + static SHELL_VAR * get_bash_command (var) SHELL_VAR *var; @@ -1452,6 +1470,9 @@ initialize_dynamic_variables () INIT_DYNAMIC_VAR ("LINENO", (char *)NULL, get_lineno, assign_lineno); VSETATTR (v, att_integer); + INIT_DYNAMIC_VAR ("BASHPID", (char *)NULL, get_bashpid, null_assign); + VSETATTR (v, att_integer|att_readonly); + #if defined (HISTORY) INIT_DYNAMIC_VAR ("HISTCMD", (char *)NULL, get_histcmd, (sh_var_assign_func_t *)NULL); VSETATTR (v, att_integer); -- 2.47.3
    ' . + &t2h_anchor('', $href, $entry) . + '  ' . + $descr . + "
    ' . + $entry . + '' . $descr . + "