From: Chet Ramey Date: Mon, 9 Jan 2012 13:24:22 +0000 (-0500) Subject: commit bash-20110720 snapshot X-Git-Tag: bash-4.3-alpha~112 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=19baff85a2c24b3becd290921ad077ecf6817df7;p=thirdparty%2Fbash.git commit bash-20110720 snapshot --- diff --git a/CWRU/CWRU.chlog b/CWRU/CWRU.chlog index ae94a34b0..78d7379b6 100644 --- a/CWRU/CWRU.chlog +++ b/CWRU/CWRU.chlog @@ -11974,3 +11974,91 @@ lib/readline/isearch.c - _rl_isearch_dispatch: when adding character to search string, use cxt->lastc (which we use in the switch statement) instead of c, since lastc can be modified earlier in the function + + 7/18 + ---- +lib/readline/rlprivate.h + - _rl_search_context: add another member to save previous value of + (multibyte) lastc: pmb is to mb as prevc is to lastc + +lib/readline/isearch.c: + - _rl_isearch_dispatch: if a key sequence indexes into a new keymap, + but doesn't find any bound function (k[ind].function == 0) or is + bound to self-insert (k[ind].function == rl_insert), back up and + insert the previous character (the one that caused the index into a + new keymap) and arrange things so the current character is the next + one read, so both of them end up in the search string. Fixes bug + reported by Clark Wang + - _rl_isearch_dispatch: a couple of efficiency improvements when adding + characters to the isearch string + + 7/24 + ---- +lib/readline/isearch.c + - _rl_isearch_dispatch: save and restore cxt->mb and cxt->pmb + appropriately when in a multibyte locale + +doc/{bash.1,bashref.texi} + - correct description of {x}>file (and other redirection operators + that allocate a file descriptor) to note the the fd range is + greater than or equal to 10. Fixes problem reported by + Christian Ullrich + +lib/readline/signals.c + - rl_signal_handler: don't interrupt immediately if in callback mode + +lib/readline/callback.c + - rl_callback_read_char: install signal handlers only when readline + has control in callback mode, so readline's signal handlers aren't + called when the application is active (e.g., between the calls to + rl_callback_handler_install and rl_callback_read_char). If the + readline signal handlers only set a flag, which the application + doesn't know about, the signals will effectively be ignored until + the next time the application calls into the readline callback + interface. Fixes problem of calling unsafe functions from signal + handlers when in callback mode reported by Jan Kratochvil + + +execute_cmd.c + - fix_assignment_words: when in Posix mode, the `command' builtin + doesn't change whether or not the command name it protects is an + assignment builtin. One or more instances of `command' + preceding `export', for instance, doesn't make `export' treat its + assignment statement arguments differently. Posix interpretation + #351 + +doc/{bash.1,bashref.texi} + - document new Posix-mode behavior of `command' when preceding builtins + that take assignment statements as arguments + +builtins/printf.def + - printstr: if fieldwidth or precision are < 0 or > INT_MAX when + supplied explicitly (since we take care of the `-' separately), + clamp at INT_MAX like when using getint(). Fixes issue reported + by Ralph Coredroy + + 7/25 + ---- +lib/readline/chardefs.h + - isxdigit: don't define if compiling with c++; declared as a c++ + template function. Fixes bug reported by Miroslav Lichvar + + +builtins/printf.def + - getint: if garglist == 0, return whatever getintmax returns (0). + Fixes bug reported by Ralph Coredroy + + 7/28 + ---- +doc/{bash.1,bashref.texi} + - minor changes to the descriptions of the cd and pushd builtins + +lib/sh/zread.c + - zsyncfd: change variable holding return value from lseek to + off_t. Bug report and fix from Gregory Margo + + 8/1 + --- +expr.c + - don't check for division by 0 when in a context where no evaluation + is taking place. Fixes bug reported by dnade.ext@orange-ftgroup.com diff --git a/CWRU/CWRU.chlog~ b/CWRU/CWRU.chlog~ index 12883edac..bb85930bf 100644 --- a/CWRU/CWRU.chlog~ +++ b/CWRU/CWRU.chlog~ @@ -11846,6 +11846,10 @@ builtins/read.def and set LINES and COLUMNS after a foreground job exits. From a suggestion by Leslie Rhorer +doc/{bash.1,bashref.texi} + - checkwinsize: remove language saying that only interactive shells + check the window size after each command + lib/readline/histfile.c - history_backupfile: new file, creates a backup history file name given a filename (appending `-') @@ -11923,3 +11927,132 @@ lib/readline/complete.c lib/readline/signals.c - rl_signal_handler: if we're in callback mode, don't interrupt immediately on a SIGWINCH + + 7/3 + --- +bashline.c + - set_directory_hook: and its siblings are a new set of functions to + set, save, and restore the appropriate directory completion hook + - change callers to use {set,save,restore}_directory_hook instead of + manipulating rl_directory_rewrite_hook directly + - dircomplete_expand: new variable, defaults to 0, if non-zero causes + directory names to be word-expanded during word and filename + completion + - change {set,save,restore}_directory_hook to look at dircomplete_expand + and change rl_directory_completion_hook or rl_directory_rewrite_hook + appropriately + +bashline.h + - extern declaration for set_directory_hook so shopt code can use it + + 7/6 + --- +builtins/shopt.def + - globasciiranges: new settable shopt option, makes glob ranges act + as if in the C locale (so b no longer comes between A and B). + Suggested by Aharon Robbins + + 7/7 + --- +doc/{bash.1,bashref.texi} + - document new `globasciiranges' shopt option + + 7/8 + --- +builtins/shopt.def + - direxpand: new settable option, makes filename completion expand + variables in directory names like bash-4.1 did. + - shopt_set_complete_direxpand: new function, does the work for the + above by calling set_directory_hook + +doc/{bash.1,bashref.texi} + - document new `direxpand' shopt option + + 7/15 + ---- +lib/readline/isearch.c + - _rl_isearch_dispatch: when adding character to search string, use + cxt->lastc (which we use in the switch statement) instead of c, + since lastc can be modified earlier in the function + + 7/18 + ---- +lib/readline/rlprivate.h + - _rl_search_context: add another member to save previous value of + (multibyte) lastc: pmb is to mb as prevc is to lastc + +lib/readline/isearch.c: + - _rl_isearch_dispatch: if a key sequence indexes into a new keymap, + but doesn't find any bound function (k[ind].function == 0) or is + bound to self-insert (k[ind].function == rl_insert), back up and + insert the previous character (the one that caused the index into a + new keymap) and arrange things so the current character is the next + one read, so both of them end up in the search string. Fixes bug + reported by Clark Wang + - _rl_isearch_dispatch: a couple of efficiency improvements when adding + characters to the isearch string + + 7/24 + ---- +lib/readline/isearch.c + - _rl_isearch_dispatch: save and restore cxt->mb and cxt->pmb + appropriately when in a multibyte locale + +doc/{bash.1,bashref.texi} + - correct description of {x}>file (and other redirection operators + that allocate a file descriptor) to note the the fd range is + greater than or equal to 10. Fixes problem reported by + Christian Ullrich + +lib/readline/signals.c + - rl_signal_handler: don't interrupt immediately if in callback mode + +lib/readline/callback.c + - rl_callback_read_char: install signal handlers only when readline + has control in callback mode, so readline's signal handlers aren't + called when the application is active (e.g., between the calls to + rl_callback_handler_install and rl_callback_read_char). If the + readline signal handlers only set a flag, which the application + doesn't know about, the signals will effectively be ignored until + the next time the application calls into the readline callback + interface. Fixes problem of calling unsafe functions from signal + handlers when in callback mode reported by Jan Kratochvil + + +execute_cmd.c + - fix_assignment_words: when in Posix mode, the `command' builtin + doesn't change whether or not the command name it protects is an + assignment builtin. One or more instances of `command' + preceding `export', for instance, doesn't make `export' treat its + assignment statement arguments differently. Posix interpretation + #351 + +doc/{bash.1,bashref.texi} + - document new Posix-mode behavior of `command' when preceding builtins + that take assignment statements as arguments + +builtins/printf.def + - printstr: if fieldwidth or precision are < 0 or > INT_MAX when + supplied explicitly (since we take care of the `-' separately), + clamp at INT_MAX like when using getint(). Fixes issue reported + by Ralph Coredroy + + 7/25 + ---- +lib/readline/chardefs.h + - isxdigit: don't define if compiling with c++; declared as a c++ + template function. Fixes bug reported by Miroslav Lichvar + + +builtins/printf.def + - getint: if garglist == 0, return whatever getintmax returns (0). + Fixes bug reported by Ralph Coredroy + + 7/28 + ---- +doc/{bash.1,bashref.texi} + - minor changes to the descriptions of the cd and pushd builtins + +lib/sh/zread.c + - zsyncfd: change variable holding return value from lseek to + off_t. Bug report and fix from Gregory Margo diff --git a/builtins/cd.def b/builtins/cd.def index b1aae26d0..27b9eef23 100644 --- a/builtins/cd.def +++ b/builtins/cd.def @@ -290,7 +290,8 @@ cd_builtin (list) free (temp); } -#if 0 /* changed for bash-4.2 Posix cd description steps 5-6 */ +#if 0 + /* changed for bash-4.2 Posix cd description steps 5-6 */ /* POSIX.2 says that if `.' does not appear in $CDPATH, we don't try the current directory, so we just punt now with an error message if POSIXLY_CORRECT is non-zero. The check for cdpath[0] diff --git a/builtins/cd.def~ b/builtins/cd.def~ new file mode 100644 index 000000000..b1aae26d0 --- /dev/null +++ b/builtins/cd.def~ @@ -0,0 +1,536 @@ +This file is cd.def, from which is created cd.c. It implements the +builtins "cd" and "pwd" in Bash. + +Copyright (C) 1987-2010 Free Software Foundation, Inc. + +This file is part of GNU Bash, the Bourne Again SHell. + +Bash is free software: you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation, either version 3 of the License, or +(at your option) any later version. + +Bash is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with Bash. If not, see . + +$PRODUCES cd.c +#include + +#if defined (HAVE_UNISTD_H) +# ifdef _MINIX +# include +# endif +# include +#endif + +#include "../bashtypes.h" +#include "posixdir.h" +#include "posixstat.h" +#ifndef _MINIX +#include +#endif + +#include + +#include "../bashansi.h" +#include "../bashintl.h" + +#include +#include + +#include "../shell.h" +#include "../flags.h" +#include "maxpath.h" +#include "common.h" +#include "bashgetopt.h" + +#if !defined (errno) +extern int errno; +#endif /* !errno */ + +extern int posixly_correct; +extern int array_needs_making; +extern const char * const bash_getcwd_errstr; + +static int bindpwd __P((int)); +static int setpwd __P((char *)); +static char *resetpwd __P((char *)); +static int change_to_directory __P((char *, int)); + +/* Change this to 1 to get cd spelling correction by default. */ +int cdspelling = 0; + +int cdable_vars; + +static int eflag; /* file scope so bindpwd() can see it */ + +$BUILTIN cd +$FUNCTION cd_builtin +$SHORT_DOC cd [-L|[-P [-e]]] [dir] +Change the shell working directory. + +Change the current directory to DIR. The default DIR is the value of the +HOME shell variable. + +The variable CDPATH defines the search path for the directory containing +DIR. Alternative directory names in CDPATH are separated by a colon (:). +A null directory name is the same as the current directory. If DIR begins +with a slash (/), then CDPATH is not used. + +If the directory is not found, and the shell option `cdable_vars' is set, +the word is assumed to be a variable name. If that variable has a value, +its value is used for DIR. + +Options: + -L force symbolic links to be followed + -P use the physical directory structure without following symbolic + links + -e if the -P option is supplied, and the current working directory + cannot be determined successfully, exit with a non-zero status + +The default is to follow symbolic links, as if `-L' were specified. + +Exit Status: +Returns 0 if the directory is changed, and if $PWD is set successfully when +-P is used; non-zero otherwise. +$END + +/* Just set $PWD, don't change OLDPWD. Used by `pwd -P' in posix mode. */ +static int +setpwd (dirname) + char *dirname; +{ + int old_anm; + SHELL_VAR *tvar; + + old_anm = array_needs_making; + tvar = bind_variable ("PWD", dirname ? dirname : "", 0); + if (tvar && readonly_p (tvar)) + return EXECUTION_FAILURE; + if (tvar && old_anm == 0 && array_needs_making && exported_p (tvar)) + { + update_export_env_inplace ("PWD=", 4, dirname ? dirname : ""); + array_needs_making = 0; + } + return EXECUTION_SUCCESS; +} + +static int +bindpwd (no_symlinks) + int no_symlinks; +{ + char *dirname, *pwdvar; + int old_anm, r; + SHELL_VAR *tvar; + + r = sh_chkwrite (EXECUTION_SUCCESS); + +#define tcwd the_current_working_directory + dirname = tcwd ? (no_symlinks ? sh_physpath (tcwd, 0) : tcwd) + : get_working_directory ("cd"); +#undef tcwd + + old_anm = array_needs_making; + pwdvar = get_string_value ("PWD"); + + tvar = bind_variable ("OLDPWD", pwdvar, 0); + if (tvar && readonly_p (tvar)) + r = EXECUTION_FAILURE; + + if (old_anm == 0 && array_needs_making && exported_p (tvar)) + { + update_export_env_inplace ("OLDPWD=", 7, pwdvar); + array_needs_making = 0; + } + + if (setpwd (dirname) == EXECUTION_FAILURE) + r = EXECUTION_FAILURE; + if (dirname == 0 && eflag) + r = EXECUTION_FAILURE; + + if (dirname && dirname != the_current_working_directory) + free (dirname); + + return (r); +} + +/* Call get_working_directory to reset the value of + the_current_working_directory () */ +static char * +resetpwd (caller) + char *caller; +{ + char *tdir; + + FREE (the_current_working_directory); + the_current_working_directory = (char *)NULL; + tdir = get_working_directory (caller); + return (tdir); +} + +#define LCD_DOVARS 0x001 +#define LCD_DOSPELL 0x002 +#define LCD_PRINTPATH 0x004 +#define LCD_FREEDIRNAME 0x008 + +/* This builtin is ultimately the way that all user-visible commands should + change the current working directory. It is called by cd_to_string (), + so the programming interface is simple, and it handles errors and + restrictions properly. */ +int +cd_builtin (list) + WORD_LIST *list; +{ + char *dirname, *cdpath, *path, *temp; + int path_index, no_symlinks, opt, lflag; + +#if defined (RESTRICTED_SHELL) + if (restricted) + { + sh_restricted ((char *)NULL); + return (EXECUTION_FAILURE); + } +#endif /* RESTRICTED_SHELL */ + + eflag = 0; + no_symlinks = no_symbolic_links; + reset_internal_getopt (); + while ((opt = internal_getopt (list, "LP")) != -1) + { + switch (opt) + { + case 'P': + no_symlinks = 1; + break; + case 'L': + no_symlinks = 0; + break; + case 'e': + eflag = 1; + break; + default: + builtin_usage (); + return (EXECUTION_FAILURE); + } + } + list = loptend; + + lflag = (cdable_vars ? LCD_DOVARS : 0) | + ((interactive && cdspelling) ? LCD_DOSPELL : 0); + if (eflag && no_symlinks == 0) + eflag = 0; + + if (list == 0) + { + /* `cd' without arguments is equivalent to `cd $HOME' */ + dirname = get_string_value ("HOME"); + + if (dirname == 0) + { + builtin_error (_("HOME not set")); + return (EXECUTION_FAILURE); + } + lflag = 0; + } + else if (list->word->word[0] == '-' && list->word->word[1] == '\0') + { + /* This is `cd -', equivalent to `cd $OLDPWD' */ + dirname = get_string_value ("OLDPWD"); + + if (dirname == 0) + { + builtin_error (_("OLDPWD not set")); + return (EXECUTION_FAILURE); + } +#if 0 + lflag = interactive ? LCD_PRINTPATH : 0; +#else + lflag = LCD_PRINTPATH; /* According to SUSv3 */ +#endif + } + else if (absolute_pathname (list->word->word)) + dirname = list->word->word; + else if (privileged_mode == 0 && (cdpath = get_string_value ("CDPATH"))) + { + dirname = list->word->word; + + /* Find directory in $CDPATH. */ + path_index = 0; + while (path = extract_colon_unit (cdpath, &path_index)) + { + /* OPT is 1 if the path element is non-empty */ + opt = path[0] != '\0'; + temp = sh_makepath (path, dirname, MP_DOTILDE); + free (path); + + if (change_to_directory (temp, no_symlinks)) + { + /* POSIX.2 says that if a nonempty directory from CDPATH + is used to find the directory to change to, the new + directory name is echoed to stdout, whether or not + the shell is interactive. */ + if (opt && (path = no_symlinks ? temp : the_current_working_directory)) + printf ("%s\n", path); + + free (temp); +#if 0 + /* Posix.2 says that after using CDPATH, the resultant + value of $PWD will not contain `.' or `..'. */ + return (bindpwd (posixly_correct || no_symlinks)); +#else + return (bindpwd (no_symlinks)); +#endif + } + else + free (temp); + } + +#if 0 /* changed for bash-4.2 Posix cd description steps 5-6 */ + /* POSIX.2 says that if `.' does not appear in $CDPATH, we don't + try the current directory, so we just punt now with an error + message if POSIXLY_CORRECT is non-zero. The check for cdpath[0] + is so we don't mistakenly treat a CDPATH value of "" as not + specifying the current directory. */ + if (posixly_correct && cdpath[0]) + { + builtin_error ("%s: %s", dirname, strerror (ENOENT)); + return (EXECUTION_FAILURE); + } +#endif + } + else + dirname = list->word->word; + + /* When we get here, DIRNAME is the directory to change to. If we + chdir successfully, just return. */ + if (change_to_directory (dirname, no_symlinks)) + { + if (lflag & LCD_PRINTPATH) + printf ("%s\n", dirname); + return (bindpwd (no_symlinks)); + } + + /* If the user requests it, then perhaps this is the name of + a shell variable, whose value contains the directory to + change to. */ + if (lflag & LCD_DOVARS) + { + temp = get_string_value (dirname); + if (temp && change_to_directory (temp, no_symlinks)) + { + printf ("%s\n", temp); + return (bindpwd (no_symlinks)); + } + } + + /* If the user requests it, try to find a directory name similar in + spelling to the one requested, in case the user made a simple + typo. This is similar to the UNIX 8th and 9th Edition shells. */ + if (lflag & LCD_DOSPELL) + { + temp = dirspell (dirname); + if (temp && change_to_directory (temp, no_symlinks)) + { + printf ("%s\n", temp); + return (bindpwd (no_symlinks)); + } + else + FREE (temp); + } + + builtin_error ("%s: %s", dirname, strerror (errno)); + return (EXECUTION_FAILURE); +} + +$BUILTIN pwd +$FUNCTION pwd_builtin +$SHORT_DOC pwd [-LP] +Print the name of the current working directory. + +Options: + -L print the value of $PWD if it names the current working + directory + -P print the physical directory, without any symbolic links + +By default, `pwd' behaves as if `-L' were specified. + +Exit Status: +Returns 0 unless an invalid option is given or the current directory +cannot be read. +$END + +/* Non-zero means that pwd always prints the physical directory, without + symbolic links. */ +static int verbatim_pwd; + +/* Print the name of the current working directory. */ +int +pwd_builtin (list) + WORD_LIST *list; +{ + char *directory; + int opt, pflag; + + verbatim_pwd = no_symbolic_links; + pflag = 0; + reset_internal_getopt (); + while ((opt = internal_getopt (list, "LP")) != -1) + { + switch (opt) + { + case 'P': + verbatim_pwd = pflag = 1; + break; + case 'L': + verbatim_pwd = 0; + break; + default: + builtin_usage (); + return (EXECUTION_FAILURE); + } + } + list = loptend; + +#define tcwd the_current_working_directory + + directory = tcwd ? (verbatim_pwd ? sh_physpath (tcwd, 0) : tcwd) + : get_working_directory ("pwd"); + + /* Try again using getcwd() if canonicalization fails (for instance, if + the file system has changed state underneath bash). */ + if ((tcwd && directory == 0) || + (posixly_correct && same_file (".", tcwd, (struct stat *)0, (struct stat *)0) == 0)) + directory = resetpwd ("pwd"); + +#undef tcwd + + if (directory) + { + opt = EXECUTION_SUCCESS; + printf ("%s\n", directory); + /* This is dumb but posix-mandated. */ + if (posixly_correct && pflag) + opt = setpwd (directory); + if (directory != the_current_working_directory) + free (directory); + return (sh_chkwrite (opt)); + } + else + return (EXECUTION_FAILURE); +} + +/* Do the work of changing to the directory NEWDIR. Handle symbolic + link following, etc. This function *must* return with + the_current_working_directory either set to NULL (in which case + getcwd() will eventually be called), or set to a string corresponding + to the working directory. Return 1 on success, 0 on failure. */ + +static int +change_to_directory (newdir, nolinks) + char *newdir; + int nolinks; +{ + char *t, *tdir; + int err, canon_failed, r, ndlen, dlen; + + tdir = (char *)NULL; + + if (the_current_working_directory == 0) + { + t = get_working_directory ("chdir"); + FREE (t); + } + + t = make_absolute (newdir, the_current_working_directory); + + /* TDIR is either the canonicalized absolute pathname of NEWDIR + (nolinks == 0) or the absolute physical pathname of NEWDIR + (nolinks != 0). */ + tdir = nolinks ? sh_physpath (t, 0) + : sh_canonpath (t, PATH_CHECKDOTDOT|PATH_CHECKEXISTS); + + ndlen = strlen (newdir); + dlen = strlen (t); + + /* Use the canonicalized version of NEWDIR, or, if canonicalization + failed, use the non-canonical form. */ + canon_failed = 0; + if (tdir && *tdir) + free (t); + else + { + FREE (tdir); + tdir = t; + canon_failed = 1; + } + + /* In POSIX mode, if we're resolving symlinks logically and sh_canonpath + returns NULL (because it checks the path, it will return NULL if the + resolved path doesn't exist), fail immediately. */ + if (posixly_correct && nolinks == 0 && canon_failed && (errno != ENAMETOOLONG || ndlen > PATH_MAX)) + { +#if defined ENAMETOOLONG + if (errno != ENOENT && errno != ENAMETOOLONG) +#else + if (errno != ENOENT) +#endif + errno = ENOTDIR; + free (tdir); + return (0); + } + + /* If the chdir succeeds, update the_current_working_directory. */ + if (chdir (nolinks ? newdir : tdir) == 0) + { + /* If canonicalization failed, but the chdir succeeded, reset the + shell's idea of the_current_working_directory. */ + if (canon_failed) + { + t = resetpwd ("cd"); + if (t == 0) + set_working_directory (tdir); + } + else + set_working_directory (tdir); + + free (tdir); + return (1); + } + + /* We failed to change to the appropriate directory name. If we tried + what the user passed (nolinks != 0), punt now. */ + if (nolinks) + { + free (tdir); + return (0); + } + + err = errno; + + /* We're not in physical mode (nolinks == 0), but we failed to change to + the canonicalized directory name (TDIR). Try what the user passed + verbatim. If we succeed, reinitialize the_current_working_directory. */ + if (chdir (newdir) == 0) + { + t = resetpwd ("cd"); + if (t == 0) + set_working_directory (tdir); + else + free (t); + + r = 1; + } + else + { + errno = err; + r = 0; + } + + free (tdir); + return r; +} diff --git a/builtins/printf.def b/builtins/printf.def index ab6aeff6a..04f4ebc6a 100644 --- a/builtins/printf.def +++ b/builtins/printf.def @@ -685,6 +685,7 @@ printstr (fmt, string, len, fieldwidth, precision) #endif int padlen, nc, ljust, i; int fw, pr; /* fieldwidth and precision */ + intmax_t mfw, mpr; #if 0 if (string == 0 || *string == '\0') @@ -701,6 +702,8 @@ printstr (fmt, string, len, fieldwidth, precision) ljust = fw = 0; pr = -1; + mfw = 0; + mpr = -1; /* skip flags */ while (strchr (SKIP1, *fmt)) @@ -710,7 +713,7 @@ printstr (fmt, string, len, fieldwidth, precision) fmt++; } - /* get fieldwidth, if present */ + /* get fieldwidth, if present. rely on caller to clamp fieldwidth at INT_MAX */ if (*fmt == '*') { fmt++; @@ -723,9 +726,11 @@ printstr (fmt, string, len, fieldwidth, precision) } else if (DIGIT (*fmt)) { - fw = *fmt++ - '0'; + mfw = *fmt++ - '0'; while (DIGIT (*fmt)) - fw = (fw * 10) + (*fmt++ - '0'); + mfw = (mfw * 10) + (*fmt++ - '0'); + /* Error if fieldwidth > INT_MAX here? */ + fw = (mfw < 0 || mfw > INT_MAX) ? INT_MAX : mfw; } /* get precision, if present */ @@ -739,9 +744,11 @@ printstr (fmt, string, len, fieldwidth, precision) } else if (DIGIT (*fmt)) { - pr = *fmt++ - '0'; + mpr = *fmt++ - '0'; while (DIGIT (*fmt)) - pr = (pr * 10) + (*fmt++ - '0'); + mpr = (mpr * 10) + (*fmt++ - '0'); + /* Error if precision > INT_MAX here? */ + pr = (mpr < 0 || mpr > INT_MAX) ? INT_MAX : mpr; } } @@ -1093,6 +1100,9 @@ getint () ret = getintmax (); + if (garglist == 0) + return ret; + if (ret > INT_MAX) { printf_erange (garglist->word->word); diff --git a/builtins/printf.def~ b/builtins/printf.def~ new file mode 100644 index 000000000..8d2d513b3 --- /dev/null +++ b/builtins/printf.def~ @@ -0,0 +1,1252 @@ +This file is printf.def, from which is created printf.c. +It implements the builtin "printf" in Bash. + +Copyright (C) 1997-2010 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 3 of the License, 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. If not, see . + +$PRODUCES printf.c + +$BUILTIN printf +$FUNCTION printf_builtin +$SHORT_DOC printf [-v var] format [arguments] +Formats and prints ARGUMENTS under control of the FORMAT. + +Options: + -v var assign the output to shell variable VAR rather than + display it on the standard output + +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 format specifications described in printf(1), +printf interprets: + + %b expand backslash escape sequences in the corresponding argument + %q quote the argument in a way that can be reused as shell input + %(fmt)T output the date-time string resulting from using FMT as a format + string for strftime(3) + +Exit Status: +Returns success unless an invalid option is given or a write or assignment +error occurs. +$END + +#include + +#include "../bashtypes.h" + +#include +#if defined (HAVE_LIMITS_H) +# include +#else + /* Assume 32-bit ints. */ +# define INT_MAX 2147483647 +# define INT_MIN (-2147483647-1) +#endif + +#if defined (PREFER_STDARG) +# include +#else +# include +#endif + +#include +#include + +#ifdef HAVE_INTTYPES_H +# include +#endif + +#include "posixtime.h" +#include "../bashansi.h" +#include "../bashintl.h" + +#define NEED_STRFTIME_DECL + +#include "../shell.h" +#include "shmbutil.h" +#include "stdc.h" +#include "bashgetopt.h" +#include "common.h" + +#if defined (PRI_MACROS_BROKEN) +# undef PRIdMAX +#endif + +#if !defined (PRIdMAX) +# if HAVE_LONG_LONG +# define PRIdMAX "lld" +# else +# define PRIdMAX "ld" +# endif +#endif + +#if !defined (errno) +extern int errno; +#endif + +#define PC(c) \ + do { \ + char b[2]; \ + tw++; \ + b[0] = c; b[1] = '\0'; \ + if (vflag) \ + vbadd (b, 1); \ + else \ + putchar (c); \ + } while (0) + +#define PF(f, func) \ + do { \ + int nw; \ + clearerr (stdout); \ + if (have_fieldwidth && have_precision) \ + nw = vflag ? vbprintf (f, fieldwidth, precision, func) : printf (f, fieldwidth, precision, func); \ + else if (have_fieldwidth) \ + nw = vflag ? vbprintf (f, fieldwidth, func) : printf (f, fieldwidth, func); \ + else if (have_precision) \ + nw = vflag ? vbprintf (f, precision, func) : printf (f, precision, func); \ + else \ + nw = vflag ? vbprintf (f, func) : printf (f, func); \ + tw += nw; \ + if (ferror (stdout)) \ + { \ + sh_wrerror (); \ + clearerr (stdout); \ + return (EXECUTION_FAILURE); \ + } \ + } while (0) + +/* We free the buffer used by mklong() if it's `too big'. */ +#define PRETURN(value) \ + do \ + { \ + if (vflag) \ + { \ + bind_printf_variable (vname, vbuf, 0); \ + stupidly_hack_special_variables (vname); \ + } \ + if (conv_bufsize > 4096 ) \ + { \ + free (conv_buf); \ + conv_bufsize = 0; \ + conv_buf = 0; \ + } \ + if (vbsize > 4096) \ + { \ + free (vbuf); \ + vbsize = 0; \ + vbuf = 0; \ + } \ + else if (vbuf) \ + vbuf[0] = 0; \ + terminate_immediately--; \ + if (ferror (stdout) == 0) \ + fflush (stdout); \ + if (ferror (stdout)) \ + { \ + sh_wrerror (); \ + clearerr (stdout); \ + return (EXECUTION_FAILURE); \ + } \ + return (value); \ + } \ + while (0) + +#define SKIP1 "#'-+ 0" +#define LENMODS "hjlLtz" + +extern time_t shell_start_time; + +#if !HAVE_ASPRINTF +extern int asprintf __P((char **, const char *, ...)) __attribute__((__format__ (printf, 2, 3))); +#endif + +#if !HAVE_VSNPRINTF +extern int vsnprintf __P((char *, size_t, const char *, va_list)) __attribute__((__format__ (printf, 3, 0))); +#endif + +static void printf_erange __P((char *)); +static int printstr __P((char *, char *, int, int, int)); +static int tescape __P((char *, char *, int *, int *)); +static char *bexpand __P((char *, int, int *, int *)); +static char *vbadd __P((char *, int)); +static int vbprintf __P((const char *, ...)) __attribute__((__format__ (printf, 1, 2))); +static char *mklong __P((char *, char *, size_t)); +static int getchr __P((void)); +static char *getstr __P((void)); +static int getint __P((void)); +static intmax_t getintmax __P((void)); +static uintmax_t getuintmax __P((void)); +static SHELL_VAR *bind_printf_variable __P((char *, char *, int)); + +#if defined (HAVE_LONG_DOUBLE) && HAVE_DECL_STRTOLD && !defined(STRTOLD_BROKEN) +typedef long double floatmax_t; +# define FLOATMAX_CONV "L" +# define strtofltmax strtold +#else +typedef double floatmax_t; +# define FLOATMAX_CONV "" +# define strtofltmax strtod +#endif +static floatmax_t getfloatmax __P((void)); + +static intmax_t asciicode __P((void)); + +static WORD_LIST *garglist; +static int retval; +static int conversion_error; + +/* printf -v var support */ +static int vflag = 0; +static char *vbuf, *vname; +static size_t vbsize; +static int vblen; + +static intmax_t tw; + +static char *conv_buf; +static size_t conv_bufsize; + +int +printf_builtin (list) + WORD_LIST *list; +{ + int ch, fieldwidth, precision; + int have_fieldwidth, have_precision; + char convch, thisch, nextch, *format, *modstart, *fmt, *start; +#if defined (HANDLE_MULTIBYTE) + char mbch[25]; /* 25 > MB_LEN_MAX, plus can handle 4-byte UTF-8 and large Unicode characters*/ + int mbind, mblen; +#endif + + conversion_error = 0; + retval = EXECUTION_SUCCESS; + + vflag = 0; + + reset_internal_getopt (); + while ((ch = internal_getopt (list, "v:")) != -1) + { + switch (ch) + { + case 'v': + vname = list_optarg; +#if defined (ARRAY_VARS) + if (legal_identifier (vname) || valid_array_reference (vname)) +#else + if (legal_identifier (vname)) +#endif + { + vflag = 1; + vblen = 0; + if (vbuf) + vbuf[0] = 0; + } + else + { + sh_invalidid (vname); + return (EX_USAGE); + } + break; + default: + builtin_usage (); + return (EX_USAGE); + } + } + list = loptend; /* skip over possible `--' */ + + if (list == 0) + { + builtin_usage (); + return (EX_USAGE); + } + + if (list->word->word == 0 || list->word->word[0] == '\0') + return (EXECUTION_SUCCESS); + + format = list->word->word; + tw = 0; + + garglist = list->next; + + /* If the format string is empty after preprocessing, return immediately. */ + if (format == 0 || *format == 0) + return (EXECUTION_SUCCESS); + + terminate_immediately++; + + /* Basic algorithm is to scan the format string for conversion + specifications -- once one is found, find out if the field + width or precision is a '*'; if it is, gather up value. Note, + format strings are reused as necessary to use up the provided + arguments, arguments of zero/null string are provided to use + up the format string. */ + do + { + tw = 0; + /* find next format specification */ + for (fmt = format; *fmt; fmt++) + { + precision = fieldwidth = 0; + have_fieldwidth = have_precision = 0; + + if (*fmt == '\\') + { + fmt++; + /* A NULL third argument to tescape means to bypass the + special processing for arguments to %b. */ +#if defined (HANDLE_MULTIBYTE) + /* Accommodate possible use of \u or \U, which can result in + multibyte characters */ + memset (mbch, '\0', sizeof (mbch)); + fmt += tescape (fmt, mbch, &mblen, (int *)NULL); + for (mbind = 0; mbind < mblen; mbind++) + PC (mbch[mbind]); +#else + fmt += tescape (fmt, &nextch, (int *)NULL, (int *)NULL); + PC (nextch); +#endif + fmt--; /* for loop will increment it for us again */ + continue; + } + + if (*fmt != '%') + { + PC (*fmt); + continue; + } + + /* ASSERT(*fmt == '%') */ + start = fmt++; + + if (*fmt == '%') /* %% prints a % */ + { + PC ('%'); + continue; + } + + /* found format specification, skip to field width */ + for (; *fmt && strchr(SKIP1, *fmt); ++fmt) + ; + + /* Skip optional field width. */ + if (*fmt == '*') + { + fmt++; + have_fieldwidth = 1; + fieldwidth = getint (); + } + else + while (DIGIT (*fmt)) + fmt++; + + /* Skip optional '.' and precision */ + if (*fmt == '.') + { + ++fmt; + if (*fmt == '*') + { + fmt++; + have_precision = 1; + precision = getint (); + } + else + { + /* Negative precisions are allowed but treated as if the + precision were missing; I would like to allow a leading + `+' in the precision number as an extension, but lots + of asprintf/fprintf implementations get this wrong. */ +#if 0 + if (*fmt == '-' || *fmt == '+') +#else + if (*fmt == '-') +#endif + fmt++; + while (DIGIT (*fmt)) + fmt++; + } + } + + /* skip possible format modifiers */ + modstart = fmt; + while (*fmt && strchr (LENMODS, *fmt)) + fmt++; + + if (*fmt == 0) + { + builtin_error (_("`%s': missing format character"), start); + PRETURN (EXECUTION_FAILURE); + } + + convch = *fmt; + thisch = modstart[0]; + nextch = modstart[1]; + modstart[0] = convch; + modstart[1] = '\0'; + + switch(convch) + { + case 'c': + { + char p; + + p = getchr (); + PF(start, p); + break; + } + + case 's': + { + char *p; + + p = getstr (); + PF(start, p); + break; + } + + case '(': + { + char *timefmt, timebuf[128], *t; + int n; + intmax_t arg; + time_t secs; + struct tm *tm; + + modstart[1] = nextch; /* restore char after left paren */ + timefmt = xmalloc (strlen (fmt) + 3); + fmt++; /* skip over left paren */ + for (t = timefmt, n = 1; *fmt; ) + { + if (*fmt == '(') + n++; + else if (*fmt == ')') + n--; + if (n == 0) + break; + *t++ = *fmt++; + } + *t = '\0'; + if (*++fmt != 'T') + { + builtin_warning (_("`%c': invalid time format specification"), *fmt); + fmt = start; + free (timefmt); + PC (*fmt); + continue; + } + if (timefmt[0] == '\0') + { + timefmt[0] = '%'; + timefmt[1] = 'X'; /* locale-specific current time - should we use `+'? */ + timefmt[2] = '\0'; + } + /* argument is seconds since the epoch with special -1 and -2 */ + arg = getintmax (); + if (arg == -1) + secs = NOW; /* roughly date +%s */ + else if (arg == -2) + secs = shell_start_time; /* roughly $SECONDS */ + else + secs = arg; +#if defined (HAVE_TZSET) + sv_tz ("TZ"); /* XXX -- just make sure */ +#endif + tm = localtime (&secs); + n = strftime (timebuf, sizeof (timebuf), timefmt, tm); + free (timefmt); + if (n == 0) + timebuf[0] = '\0'; + else + timebuf[sizeof(timebuf) - 1] = '\0'; + /* convert to %s format that preserves fieldwidth and precision */ + modstart[0] = 's'; + modstart[1] = '\0'; + n = printstr (start, timebuf, strlen (timebuf), fieldwidth, precision); /* XXX - %s for now */ + if (n < 0) + { + if (ferror (stdout) == 0) + { + sh_wrerror (); + clearerr (stdout); + } + PRETURN (EXECUTION_FAILURE); + } + break; + } + + case 'n': + { + char *var; + + var = getstr (); + if (var && *var) + { + if (legal_identifier (var)) + bind_var_to_int (var, tw); + else + { + sh_invalidid (var); + PRETURN (EXECUTION_FAILURE); + } + } + break; + } + + case 'b': /* expand escapes in argument */ + { + char *p, *xp; + int rlen, r; + + p = getstr (); + ch = rlen = r = 0; + xp = bexpand (p, strlen (p), &ch, &rlen); + + if (xp) + { + /* Have to use printstr because of possible NUL bytes + in XP -- printf does not handle that well. */ + r = printstr (start, xp, rlen, fieldwidth, precision); + if (r < 0) + { + if (ferror (stdout) == 0) + { + sh_wrerror (); + clearerr (stdout); + } + retval = EXECUTION_FAILURE; + } + free (xp); + } + + if (ch || r < 0) + PRETURN (retval); + break; + } + + case 'q': /* print with shell quoting */ + { + char *p, *xp; + int r; + + r = 0; + p = getstr (); + if (p && *p == 0) /* XXX - getstr never returns null */ + xp = savestring ("''"); + else if (ansic_shouldquote (p)) + xp = ansic_quote (p, 0, (int *)0); + else + xp = sh_backslash_quote (p); + if (xp) + { + /* Use printstr to get fieldwidth and precision right. */ + r = printstr (start, xp, strlen (xp), fieldwidth, precision); + if (r < 0) + { + sh_wrerror (); + clearerr (stdout); + } + free (xp); + } + + if (r < 0) + PRETURN (EXECUTION_FAILURE); + break; + } + + case 'd': + case 'i': + { + char *f; + long p; + intmax_t pp; + + p = pp = getintmax (); + if (p != pp) + { + f = mklong (start, PRIdMAX, sizeof (PRIdMAX) - 2); + PF (f, pp); + } + else + { + /* Optimize the common case where the integer fits + in "long". This also works around some long + long and/or intmax_t library bugs in the common + case, e.g. glibc 2.2 x86. */ + f = mklong (start, "l", 1); + PF (f, p); + } + break; + } + + case 'o': + case 'u': + case 'x': + case 'X': + { + char *f; + unsigned long p; + uintmax_t pp; + + p = pp = getuintmax (); + if (p != pp) + { + f = mklong (start, PRIdMAX, sizeof (PRIdMAX) - 2); + PF (f, pp); + } + else + { + f = mklong (start, "l", 1); + PF (f, p); + } + break; + } + + case 'e': + case 'E': + case 'f': + case 'F': + case 'g': + case 'G': +#if defined (HAVE_PRINTF_A_FORMAT) + case 'a': + case 'A': +#endif + { + char *f; + floatmax_t p; + + p = getfloatmax (); + f = mklong (start, FLOATMAX_CONV, sizeof(FLOATMAX_CONV) - 1); + PF (f, p); + break; + } + + /* We don't output unrecognized format characters; we print an + error message and return a failure exit status. */ + default: + builtin_error (_("`%c': invalid format character"), convch); + PRETURN (EXECUTION_FAILURE); + } + + modstart[0] = thisch; + modstart[1] = nextch; + } + + if (ferror (stdout)) + { + /* PRETURN will print error message. */ + PRETURN (EXECUTION_FAILURE); + } + } + while (garglist && garglist != list->next); + + if (conversion_error) + retval = EXECUTION_FAILURE; + + PRETURN (retval); +} + +static void +printf_erange (s) + char *s; +{ + builtin_error (_("warning: %s: %s"), s, strerror(ERANGE)); +} + +/* We duplicate a lot of what printf(3) does here. */ +static int +printstr (fmt, string, len, fieldwidth, precision) + char *fmt; /* format */ + char *string; /* expanded string argument */ + int len; /* length of expanded string */ + int fieldwidth; /* argument for width of `*' */ + int precision; /* argument for precision of `*' */ +{ +#if 0 + char *s; +#endif + int padlen, nc, ljust, i; + int fw, pr; /* fieldwidth and precision */ + intmax_t mfw, mpr; + +#if 0 + if (string == 0 || *string == '\0') +#else + if (string == 0 || len == 0) +#endif + return 0; + +#if 0 + s = fmt; +#endif + if (*fmt == '%') + fmt++; + + ljust = fw = 0; + pr = -1; + mfw = 0; + mpr = -1; + + /* skip flags */ + while (strchr (SKIP1, *fmt)) + { + if (*fmt == '-') + ljust = 1; + fmt++; + } + + /* get fieldwidth, if present. rely on caller to clamp fieldwidth at INT_MAX */ + if (*fmt == '*') + { + fmt++; + fw = fieldwidth; + if (fw < 0) + { + fw = -fw; + ljust = 1; + } + } + else if (DIGIT (*fmt)) + { + mfw = *fmt++ - '0'; + while (DIGIT (*fmt)) + mfw = (mfw * 10) + (*fmt++ - '0'); + fw = (mfw < 0 || mfw > INT_MAX) ? INT_MAX : mfw; + } + + /* get precision, if present */ + if (*fmt == '.') + { + fmt++; + if (*fmt == '*') + { + fmt++; + pr = precision; + } + else if (DIGIT (*fmt)) + { + mpr = *fmt++ - '0'; + while (DIGIT (*fmt)) + mpr = (mpr * 10) + (*fmt++ - '0'); + pr = (mpr < 0 || mpr > INT_MAX) ? INT_MAX : mpr; + } + } + +#if 0 + /* If we remove this, get rid of `s'. */ + if (*fmt != 'b' && *fmt != 'q') + { + internal_error ("format parsing problem: %s", s); + fw = pr = 0; + } +#endif + + /* chars from string to print */ + nc = (pr >= 0 && pr <= len) ? pr : len; + + padlen = fw - nc; + if (padlen < 0) + padlen = 0; + if (ljust) + padlen = -padlen; + + /* leading pad characters */ + for (; padlen > 0; padlen--) + PC (' '); + + /* output NC characters from STRING */ + for (i = 0; i < nc; i++) + PC (string[i]); + + /* output any necessary trailing padding */ + for (; padlen < 0; padlen++) + PC (' '); + + return (ferror (stdout) ? -1 : 0); +} + +/* Convert STRING by expanding the escape sequences specified by the + POSIX standard for printf's `%b' format string. If SAWC is non-null, + perform the processing appropriate for %b arguments. In particular, + recognize `\c' and use that as a string terminator. If we see \c, set + *SAWC to 1 before returning. LEN is the length of STRING. */ + +/* Translate a single backslash-escape sequence starting at ESTART (the + character after the backslash) and return the number of characters + consumed by the sequence. CP is the place to return the translated + value. *SAWC is set to 1 if the escape sequence was \c, since that means + to short-circuit the rest of the processing. If SAWC is null, we don't + do the \c short-circuiting, and \c is treated as an unrecognized escape + sequence; we also bypass the other processing specific to %b arguments. */ +static int +tescape (estart, cp, lenp, sawc) + char *estart; + char *cp; + int *lenp, *sawc; +{ + register char *p; + int temp, c, evalue; + unsigned long uvalue; + + p = estart; + if (lenp) + *lenp = 1; + + switch (c = *p++) + { +#if defined (__STDC__) + case 'a': *cp = '\a'; break; +#else + case 'a': *cp = '\007'; break; +#endif + + case 'b': *cp = '\b'; break; + + case 'e': + case 'E': *cp = '\033'; break; /* ESC -- non-ANSI */ + + case 'f': *cp = '\f'; break; + + case 'n': *cp = '\n'; break; + + case 'r': *cp = '\r'; break; + + case 't': *cp = '\t'; break; + + case 'v': *cp = '\v'; break; + + /* The octal escape sequences are `\0' followed by up to three octal + digits (if SAWC), or `\' followed by up to three octal digits (if + !SAWC). As an extension, we allow the latter form even if SAWC. */ + case '0': case '1': case '2': case '3': + case '4': case '5': case '6': case '7': + evalue = OCTVALUE (c); + for (temp = 2 + (!evalue && !!sawc); ISOCTAL (*p) && temp--; p++) + evalue = (evalue * 8) + OCTVALUE (*p); + *cp = evalue & 0xFF; + break; + + /* And, as another extension, we allow \xNN, where each N is a + hex digit. */ + case 'x': + for (temp = 2, evalue = 0; ISXDIGIT ((unsigned char)*p) && temp--; p++) + evalue = (evalue * 16) + HEXVALUE (*p); + if (p == estart + 1) + { + builtin_error (_("missing hex digit for \\x")); + *cp = '\\'; + return 0; + } + *cp = evalue & 0xFF; + break; + +#if defined (HANDLE_MULTIBYTE) + case 'u': + case 'U': + temp = (c == 'u') ? 4 : 8; /* \uNNNN \UNNNNNNNN */ + for (uvalue = 0; ISXDIGIT ((unsigned char)*p) && temp--; p++) + uvalue = (uvalue * 16) + HEXVALUE (*p); + if (p == estart + 1) + { + builtin_error (_("missing unicode digit for \\%c"), c); + *cp = '\\'; + return 0; + } + if (uvalue <= UCHAR_MAX) + *cp = uvalue; + else + { + temp = u32cconv (uvalue, cp); + cp[temp] = '\0'; + if (lenp) + *lenp = temp; + } + break; +#endif + + case '\\': /* \\ -> \ */ + *cp = c; + break; + + /* SAWC == 0 means that \', \", and \? are recognized as escape + sequences, though the only processing performed is backslash + removal. */ + case '\'': case '"': case '?': + if (!sawc) + *cp = c; + else + { + *cp = '\\'; + return 0; + } + break; + + case 'c': + if (sawc) + { + *sawc = 1; + break; + } + /* other backslash escapes are passed through unaltered */ + default: + *cp = '\\'; + return 0; + } + return (p - estart); +} + +static char * +bexpand (string, len, sawc, lenp) + char *string; + int len, *sawc, *lenp; +{ + int temp; + char *ret, *r, *s, c; +#if defined (HANDLE_MULTIBYTE) + char mbch[25]; + int mbind, mblen; +#endif + + if (string == 0 || len == 0) + { + if (sawc) + *sawc = 0; + if (lenp) + *lenp = 0; + return ((char *)NULL); + } + + ret = (char *)xmalloc (len + 1); + for (r = ret, s = string; s && *s; ) + { + c = *s++; + if (c != '\\' || *s == '\0') + { + *r++ = c; + continue; + } + temp = 0; +#if defined (HANDLE_MULTIBYTE) + memset (mbch, '\0', sizeof (mbch)); + s += tescape (s, mbch, &mblen, &temp); +#else + s += tescape (s, &c, (int *)NULL, &temp); +#endif + if (temp) + { + if (sawc) + *sawc = 1; + break; + } + +#if defined (HANDLE_MULTIBYTE) + for (mbind = 0; mbind < mblen; mbind++) + *r++ = mbch[mbind]; +#else + *r++ = c; +#endif + } + + *r = '\0'; + if (lenp) + *lenp = r - ret; + return ret; +} + +static char * +vbadd (buf, blen) + char *buf; + int blen; +{ + size_t nlen; + + nlen = vblen + blen + 1; + if (nlen >= vbsize) + { + vbsize = ((nlen + 63) >> 6) << 6; + vbuf = (char *)xrealloc (vbuf, vbsize); + } + + if (blen == 1) + vbuf[vblen++] = buf[0]; + else if (blen > 1) + { + FASTCOPY (buf, vbuf + vblen, blen); + vblen += blen; + } + vbuf[vblen] = '\0'; + +#ifdef DEBUG + if (strlen (vbuf) != vblen) + internal_error ("printf:vbadd: vblen (%d) != strlen (vbuf) (%d)", vblen, (int)strlen (vbuf)); +#endif + + return vbuf; +} + +static int +#if defined (PREFER_STDARG) +vbprintf (const char *format, ...) +#else +vbprintf (format, va_alist) + const char *format; + va_dcl +#endif +{ + va_list args; + size_t nlen; + int blen; + + SH_VA_START (args, format); + blen = vsnprintf (vbuf + vblen, vbsize - vblen, format, args); + va_end (args); + + nlen = vblen + blen + 1; + if (nlen >= vbsize) + { + vbsize = ((nlen + 63) >> 6) << 6; + vbuf = (char *)xrealloc (vbuf, vbsize); + SH_VA_START (args, format); + blen = vsnprintf (vbuf + vblen, vbsize - vblen, format, args); + va_end (args); + } + + vblen += blen; + vbuf[vblen] = '\0'; + +#ifdef DEBUG + if (strlen (vbuf) != vblen) + internal_error ("printf:vbadd: vblen (%d) != strlen (vbuf) (%d)", vblen, (int)strlen (vbuf)); +#endif + + return (blen); +} + +static char * +mklong (str, modifiers, mlen) + char *str; + char *modifiers; + size_t mlen; +{ + size_t len, slen; + + slen = strlen (str); + len = slen + mlen + 1; + + if (len > conv_bufsize) + { + conv_bufsize = (((len + 1023) >> 10) << 10); + conv_buf = (char *)xrealloc (conv_buf, conv_bufsize); + } + + FASTCOPY (str, conv_buf, slen - 1); + FASTCOPY (modifiers, conv_buf + slen - 1, mlen); + + conv_buf[len - 2] = str[slen - 1]; + conv_buf[len - 1] = '\0'; + return (conv_buf); +} + +static int +getchr () +{ + int ret; + + if (garglist == 0) + return ('\0'); + + ret = (int)garglist->word->word[0]; + garglist = garglist->next; + return ret; +} + +static char * +getstr () +{ + char *ret; + + if (garglist == 0) + return (""); + + ret = garglist->word->word; + garglist = garglist->next; + return ret; +} + +static int +getint () +{ + intmax_t ret; + + ret = getintmax (); + + if (garglist == 0) + return ret; + + if (ret > INT_MAX) + { + printf_erange (garglist->word->word); + ret = INT_MAX; + } + else if (ret < INT_MIN) + { + printf_erange (garglist->word->word); + ret = INT_MIN; + } + + return ((int)ret); +} + +static intmax_t +getintmax () +{ + intmax_t ret; + char *ep; + + if (garglist == 0) + return (0); + + if (garglist->word->word[0] == '\'' || garglist->word->word[0] == '"') + return asciicode (); + + errno = 0; + ret = strtoimax (garglist->word->word, &ep, 0); + + if (*ep) + { + sh_invalidnum (garglist->word->word); + /* POSIX.2 says ``...a diagnostic message shall be written to standard + error, and the utility shall not exit with a zero exit status, but + shall continue processing any remaining operands and shall write the + value accumulated at the time the error was detected to standard + output.'' Yecch. */ +#if 0 + ret = 0; /* return partially-converted value from strtoimax */ +#endif + conversion_error = 1; + } + else if (errno == ERANGE) + printf_erange (garglist->word->word); + + garglist = garglist->next; + return (ret); +} + +static uintmax_t +getuintmax () +{ + uintmax_t ret; + char *ep; + + if (garglist == 0) + return (0); + + if (garglist->word->word[0] == '\'' || garglist->word->word[0] == '"') + return asciicode (); + + errno = 0; + ret = strtoumax (garglist->word->word, &ep, 0); + + if (*ep) + { + sh_invalidnum (garglist->word->word); + /* Same POSIX.2 conversion error requirements as getintmax(). */ + ret = 0; + conversion_error = 1; + } + else if (errno == ERANGE) + printf_erange (garglist->word->word); + + garglist = garglist->next; + return (ret); +} + +static floatmax_t +getfloatmax () +{ + floatmax_t ret; + char *ep; + + if (garglist == 0) + return (0); + + if (garglist->word->word[0] == '\'' || garglist->word->word[0] == '"') + return asciicode (); + + errno = 0; + ret = strtofltmax (garglist->word->word, &ep); + + if (*ep) + { + sh_invalidnum (garglist->word->word); + /* Same thing about POSIX.2 conversion error requirements. */ + ret = 0; + conversion_error = 1; + } + else if (errno == ERANGE) + printf_erange (garglist->word->word); + + garglist = garglist->next; + return (ret); +} + +/* NO check is needed for garglist here. */ +static intmax_t +asciicode () +{ + register intmax_t ch; +#if defined (HANDLE_MULTIBYTE) + wchar_t wc; + size_t mblength, slen; +#endif + DECLARE_MBSTATE; + +#if defined (HANDLE_MULTIBYTE) + slen = strlen (garglist->word->word+1); + mblength = MBLEN (garglist->word->word+1, slen); + if (mblength > 1) + { + mblength = mbtowc (&wc, garglist->word->word+1, slen); + ch = wc; /* XXX */ + } + else +#endif + ch = (unsigned char)garglist->word->word[1]; + + garglist = garglist->next; + return (ch); +} + +static SHELL_VAR * +bind_printf_variable (name, value, flags) + char *name; + char *value; + int flags; +{ +#if defined (ARRAY_VARS) + if (valid_array_reference (name) == 0) + return (bind_variable (name, value, flags)); + else + return (assign_array_element (name, value, flags)); +#else /* !ARRAY_VARS */ + return bind_variable (name, value, flags); +#endif /* !ARRAY_VARS */ +} diff --git a/doc/bash.1 b/doc/bash.1 index 4a340c82d..2b7a9b903 100644 --- a/doc/bash.1 +++ b/doc/bash.1 @@ -5,12 +5,12 @@ .\" Case Western Reserve University .\" chet@po.cwru.edu .\" -.\" Last Change: Thu Jul 7 07:26:51 EDT 2011 +.\" Last Change: Thu Jul 28 18:11:21 EDT 2011 .\" .\" bash_builtins, strip all but Built-Ins section .if \n(zZ=1 .ig zZ .if \n(zY=1 .ig zY -.TH BASH 1 "2011 July 7" "GNU Bash 4.2" +.TH BASH 1 "2011 July 28" "GNU Bash 4.2" .\" .\" There's some problem with having a `@' .\" in a tagged paragraph with the BSD man macros. @@ -1207,6 +1207,9 @@ Assignment statements may also appear as arguments to the and .B local builtin commands. +When in \fIposix mode\fP, these builtins may appear in a command after +one or more instances of the \fBcommand\fP builtin and retain these +assignment statement properties. .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 @@ -3376,7 +3379,8 @@ Each redirection that may be preceded by a file descriptor number may instead be preceded by a word of the form {\fIvarname\fP}. In this case, for each redirection operator except >&- and <&-, the shell will allocate a file descriptor greater -than 10 and assign it to \fIvarname\fP. If >&- or <&- is preceded +than or equal to 10 and assign it to \fIvarname\fP. +If >&- or <&- is preceded by {\fIvarname\fP}, the value of \fIvarname\fP defines the file descriptor to close. .PP @@ -6852,9 +6856,10 @@ after a successful directory change, \fBcd\fP will return an unsuccessful status. An argument of .B \- -is equivalent to +is converted to .SM -.BR $OLDPWD . +.B $OLDPWD +before the directory change is attempted. If a non-empty directory name from .SM .B CDPATH @@ -8259,7 +8264,8 @@ starting with zero) is at the top. Adds .I dir to the directory stack at the top, making it the -new current working directory. +new current working directory as if it had been supplied as the argument +to the \fBcd\fP builtin. .PD .PP If the diff --git a/doc/bash.1~ b/doc/bash.1~ new file mode 100644 index 000000000..8d00a4f57 --- /dev/null +++ b/doc/bash.1~ @@ -0,0 +1,9981 @@ +.\" +.\" MAN PAGE COMMENTS to +.\" +.\" Chet Ramey +.\" Case Western Reserve University +.\" chet@po.cwru.edu +.\" +.\" Last Change: Sun Jul 24 13:20:45 EDT 2011 +.\" +.\" bash_builtins, strip all but Built-Ins section +.if \n(zZ=1 .ig zZ +.if \n(zY=1 .ig zY +.TH BASH 1 "2011 July 24" "GNU Bash 4.2" +.\" +.\" There's some problem with having a `@' +.\" in a tagged paragraph with the BSD man macros. +.\" It has to do with `@' appearing in the }1 macro. +.\" This is a problem on 4.3 BSD and Ultrix, but Sun +.\" appears to have fixed it. +.\" If you're seeing the characters +.\" `@u-3p' appearing before the lines reading +.\" `possible-hostname-completions +.\" and `complete-hostname' down in READLINE, +.\" then uncomment this redefinition. +.\" +.de }1 +.ds ]X \&\\*(]B\\ +.nr )E 0 +.if !"\\$1"" .nr )I \\$1n +.}f +.ll \\n(LLu +.in \\n()Ru+\\n(INu+\\n()Iu +.ti \\n(INu +.ie !\\n()Iu+\\n()Ru-\w\\*(]Xu-3p \{\\*(]X +.br\} +.el \\*(]X\h|\\n()Iu+\\n()Ru\c +.}f +.. +.\" +.\" File Name macro. This used to be `.PN', for Path Name, +.\" but Sun doesn't seem to like that very much. +.\" +.de FN +\fI\|\\$1\|\fP +.. +.SH NAME +bash \- GNU Bourne-Again SHell +.SH SYNOPSIS +.B bash +[options] +[file] +.SH COPYRIGHT +.if n Bash is Copyright (C) 1989-2011 by the Free Software Foundation, Inc. +.if t Bash is Copyright \(co 1989-2011 by the Free Software Foundation, Inc. +.SH DESCRIPTION +.B Bash +is an \fBsh\fR-compatible command language interpreter that +executes commands read from the standard input or from a file. +.B Bash +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 +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 +All of the single-character shell options documented in the +description of the \fBset\fR builtin command can be used as options +when the shell is invoked. +In addition, \fBbash\fR +interprets the following options when it is invoked: +.PP +.PD 0 +.TP 10 +.BI \-c "\| string\^" +If the +.B \-c +option is present, then commands are read from +.IR string . +If there are arguments after the +.IR string , +they are assigned to the positional parameters, starting with +.BR $0 . +.TP +.B \-i +If the +.B \-i +option is present, the shell is +.IR interactive . +.TP +.B \-l +Make +.B bash +act as if it had been invoked as a login shell (see +.SM +.B INVOCATION +below). +.TP +.B \-r +If the +.B \-r +option is present, the shell becomes +.I restricted +(see +.SM +.B "RESTRICTED SHELL" +below). +.TP +.B \-s +If the +.B \-s +option is present, or if no arguments remain after option +processing, then commands are read from the standard input. +This option allows the positional parameters to be set +when invoking an interactive shell. +.TP +.B \-D +A list of all double-quoted strings preceded by \fB$\fP +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. +This implies the \fB\-n\fP option; no commands will be executed. +.TP +.B [\-+]O [\fIshopt_option\fP] +\fIshopt_option\fP is one of the shell options accepted by the +\fBshopt\fP builtin (see +.SM +.B SHELL BUILTIN COMMANDS +below). +If \fIshopt_option\fP is present, \fB\-O\fP sets the value of that option; +\fB+O\fP unsets it. +If \fIshopt_option\fP is not supplied, the names and values of the shell +options accepted by \fBshopt\fP are printed on the standard output. +If the invocation option is \fB+O\fP, the output is displayed in a format +that may be reused as input. +.TP +.B \-\- +A +.B \-\- +signals the end of options and disables further option processing. +Any arguments after the +.B \-\- +are treated as filenames and arguments. An argument of +.B \- +is equivalent to \fB\-\-\fP. +.PD +.PP +.B Bash +also interprets a number of multi-character options. +These options must appear on the command line before the +single-character options to be recognized. +.PP +.PD 0 +.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 +.B extdebug +option to the +.B shopt +builtin below). +.TP +.B \-\-dump\-po\-strings +Equivalent to \fB\-D\fP, but the output is in the GNU \fIgettext\fP +\fBpo\fP (portable object) file format. +.TP +.B \-\-dump\-strings +Equivalent to \fB\-D\fP. +.TP +.B \-\-help +Display a usage message on standard output and exit successfully. +.TP +\fB\-\-init\-file\fP \fIfile\fP +.PD 0 +.TP +\fB\-\-rcfile\fP \fIfile\fP +.PD +Execute commands from +.I file +instead of the standard personal initialization file +.I ~/.bashrc +if the shell is interactive (see +.SM +.B INVOCATION +below). +.TP +.B \-\-login +Equivalent to \fB\-l\fP. +.TP +.B \-\-noediting +Do not use the GNU +.B readline +library to read command lines when the shell is interactive. +.TP +.B \-\-noprofile +Do not read either the system-wide startup file +.FN /etc/profile +or any of the personal initialization files +.IR ~/.bash_profile , +.IR ~/.bash_login , +or +.IR ~/.profile . +By default, +.B bash +reads these files when it is invoked as a login shell (see +.SM +.B INVOCATION +below). +.TP +.B \-\-norc +Do not read and execute the personal initialization file +.I ~/.bashrc +if the shell is interactive. +This option is on by default if the shell is invoked as +.BR sh . +.TP +.B \-\-posix +Change the behavior of \fBbash\fP where the default operation differs +from the POSIX standard to match the standard (\fIposix mode\fP). +.TP +.B \-\-restricted +The shell becomes restricted (see +.SM +.B "RESTRICTED SHELL" +below). +.TP +.B \-\-verbose +Equivalent to \fB\-v\fP. +.TP +.B \-\-version +Show version information for this instance of +.B bash +on the standard output and exit successfully. +.PD +.SH ARGUMENTS +If arguments remain after option processing, and neither the +.B \-c +nor the +.B \-s +option has been supplied, the first argument is assumed to +be the name of a file containing shell commands. +If +.B bash +is invoked in this fashion, +.B $0 +is set to the name of the file, and the positional parameters +are set to the remaining arguments. +.B Bash +reads and executes commands from this file, then exits. +\fBBash\fP'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. +An attempt is first made to open the file in the current directory, and, +if no file is found, then the shell searches the directories in +.SM +.B PATH +for the script. +.SH INVOCATION +A \fIlogin shell\fP is one whose first character of argument zero is a +.BR \- , +or one started with the +.B \-\-login +option. +.PP +An \fIinteractive\fP shell is one started without non-option arguments +and without the +.B \-c +option +whose standard input and error are +both connected to terminals (as determined by +.IR isatty (3)), +or one started with the +.B \-i +option. +.SM +.B PS1 +is set and +.B $\- +includes +.B i +if +.B bash +is interactive, +allowing a shell script or a startup file to test this state. +.PP +The following paragraphs describe how +.B bash +executes its startup files. +If any of the files exist but cannot be read, +.B bash +reports an error. +Tildes are expanded in file names as described below under +.B "Tilde Expansion" +in the +.SM +.B EXPANSION +section. +.PP +When +.B bash +is invoked as an interactive login shell, or as a non-interactive shell +with the \fB\-\-login\fP option, it first reads and +executes commands from the file \fI/etc/profile\fP, if that +file exists. +After reading that file, it looks for \fI~/.bash_profile\fP, +\fI~/.bash_login\fP, and \fI~/.profile\fP, in that order, and reads +and executes commands from the first one that exists and is readable. +The +.B \-\-noprofile +option may be used when the shell is started to inhibit this behavior. +.PP +When a login shell exits, +.B bash +reads and executes commands from the file \fI~/.bash_logout\fP, if it +exists. +.PP +When an interactive shell that is not a login shell is started, +.B bash +reads and executes commands from \fI~/.bashrc\fP, if that file exists. +This may be inhibited by using the +.B \-\-norc +option. +The \fB\-\-rcfile\fP \fIfile\fP option will force +.B bash +to read and execute commands from \fIfile\fP instead of \fI~/.bashrc\fP. +.PP +When +.B bash +is started non-interactively, to run a shell script, for example, it +looks for the variable +.SM +.B BASH_ENV +in the environment, expands its value if it appears there, and uses the +expanded value as the name of a file to read and execute. +.B Bash +behaves as if the following command were executed: +.sp .5 +.RS +.if t \f(CWif [ \-n "$BASH_ENV" ]; then . "$BASH_ENV"; fi\fP +.if n if [ \-n "$BASH_ENV" ]; then . "$BASH_ENV"; fi +.RE +.sp .5 +but the value of the +.SM +.B PATH +variable is not used to search for the file name. +.PP +If +.B bash +is invoked with the name +.BR sh , +it tries to mimic the startup behavior of historical versions of +.B sh +as closely as possible, +while conforming to the POSIX standard as well. +When invoked as an interactive login shell, or a non-interactive +shell with the \fB\-\-login\fP option, it first attempts to +read and execute commands from +.I /etc/profile +and +.IR ~/.profile , +in that order. +The +.B \-\-noprofile +option may be used to inhibit this behavior. +When invoked as an interactive shell with the name +.BR sh , +.B bash +looks for the variable +.SM +.BR 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 +.B sh +does not attempt to read and execute commands from any other startup +files, the +.B \-\-rcfile +option has no effect. +A non-interactive shell invoked with the name +.B sh +does not attempt to read any other startup files. +When invoked as +.BR sh , +.B bash +enters +.I posix +mode after the startup files are read. +.PP +When +.B bash +is started in +.I posix +mode, as with the +.B \-\-posix +command line option, it follows the POSIX standard for startup files. +In this mode, interactive shells expand the +.SM +.B ENV +variable and commands are read and executed from the file +whose name is the expanded value. +No other startup files are read. +.PP +.B Bash +attempts to determine when it is being run with its standard input +connected to a network connection, as when executed by the remote shell +daemon, usually \fIrshd\fP, or the secure shell daemon \fIsshd\fP. +If +.B bash +determines it is being run in this fashion, it reads and executes +commands from \fI~/.bashrc\fP, if that file exists and is readable. +It will not do this if invoked as \fBsh\fP. +The +.B \-\-norc +option may be used to inhibit this behavior, and the +.B \-\-rcfile +option may be used to force another file to be read, but +\fIrshd\fP does not generally invoke the shell with those options +or allow them to be specified. +.PP +If the shell is started with the effective user (group) id not equal to the +real user (group) id, and the \fB\-p\fP option is not supplied, no startup +files are read, shell functions are not inherited from the environment, the +.SM +.BR SHELLOPTS , +.SM +.BR BASHOPTS , +.SM +.BR CDPATH , +and +.SM +.B GLOBIGNORE +variables, if they appear in the environment, are ignored, +and the effective user id is set to the real user id. +If the \fB\-p\fP option is supplied at invocation, the startup behavior is +the same, but the effective user id is not reset. +.SH DEFINITIONS +.PP +The following definitions are used throughout the rest of this +document. +.PD 0 +.TP +.B blank +A space or tab. +.TP +.B word +A sequence of characters considered as a single unit by the shell. +Also known as a +.BR token . +.TP +.B name +A +.I word +consisting only of alphanumeric characters and underscores, and +beginning with an alphabetic character or an underscore. Also +referred to as an +.BR identifier . +.TP +.B metacharacter +A character that, when unquoted, separates words. One of the following: +.br +.RS +.PP +.if t \fB| & ; ( ) < > space tab\fP +.if n \fB| & ; ( ) < > space tab\fP +.RE +.PP +.TP +.B control operator +A \fItoken\fP that performs a control function. It is one of the following +symbols: +.RS +.PP +.if t \fB|| & && ; ;; ( ) | |& \fP +.if n \fB|| & && ; ;; ( ) | |& \fP +.RE +.PD +.SH "RESERVED WORDS" +\fIReserved words\fP are words that have a special meaning to the shell. +The following words are recognized as reserved when unquoted and either +the first word of a simple command (see +.SM +.B SHELL GRAMMAR +below) or the third word of a +.B case +or +.B for +command: +.if t .RS +.PP +.B +.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 +.SH "SHELL GRAMMAR" +.SS Simple Commands +.PP +A \fIsimple command\fP is a sequence of optional variable assignments +followed by \fBblank\fP-separated words and redirections, and +terminated by a \fIcontrol operator\fP. The first word +specifies the command to be executed, and is passed as argument zero. +The remaining words are passed as arguments to the invoked command. +.PP +The return value of a \fIsimple command\fP is its exit status, or +128+\fIn\^\fP if the command is terminated by signal +.IR n . +.SS Pipelines +.PP +A \fIpipeline\fP is a sequence of one or more commands separated by +one of the control operators +.B | +or \fB|&\fP. +The format for a pipeline is: +.RS +.PP +[\fBtime\fP [\fB\-p\fP]] [ ! ] \fIcommand\fP [ [\fB|\fP\(bv\fB|&\fP] \fIcommand2\fP ... ] +.RE +.PP +The standard output of +.I command +is connected via a pipe to the standard input of +.IR command2 . +This connection is performed before any redirections specified by the +command (see +.SM +.B REDIRECTION +below). +If \fB|&\fP is used, the standard error of \fIcommand\fP is connected to +\fIcommand2\fP's standard input through the pipe; it is shorthand for +\fB2>&1 |\fP. +This implicit redirection of the standard error is performed after any +redirections specified by the command. +.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 +negation of the exit status as described above. +The shell waits for all commands in the pipeline to +terminate before returning a value. +.PP +If the +.B time +reserved word precedes a pipeline, the elapsed as well as user and +system time consumed by its execution are reported when the pipeline +terminates. +The \fB\-p\fP option changes the output format to that specified by POSIX. +When the shell is in \fIposix mode\fP, it does not recognize +\fBtime\fP as a reserved word if the next token begins with a `-'. +The +.SM +.B TIMEFORMAT +variable may be set to a format string that specifies how the timing +information should be displayed; see the description of +.SM +.B TIMEFORMAT +under +.B "Shell Variables" +below. +.PP +When the shell is in \fIposix mode\fP, \fBtime\fP +may be followed by a newline. In this case, the shell displays the +total user and system time consumed by the shell and its children. +The +.SM +.B TIMEFORMAT +variable may be used to specify the format of +the time information. +.PP +Each command in a pipeline is executed as a separate process (i.e., in a +subshell). +.SS Lists +.PP +A \fIlist\fP is a sequence of one or more pipelines separated by one +of the operators +.BR ; , +.BR & , +.BR && , +or +.BR || , +and optionally terminated by one of +.BR ; , +.BR & , +or +.BR . +.PP +Of these list operators, +.B && +and +.B || +have equal precedence, followed by +.B ; +and +.BR & , +which have equal precedence. +.PP +A sequence of one or more newlines may appear in a \fIlist\fP instead +of a semicolon to delimit commands. +.PP +If a command is terminated by the control operator +.BR & , +the shell executes the command in the \fIbackground\fP +in a subshell. The shell does not wait for the command to +finish, and the return status is 0. Commands separated by a +.B ; +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. +.PP +AND and OR lists are sequences of one of more pipelines separated by the +\fB&&\fP and \fB||\fP control operators, respectively. +AND and OR lists are executed with left associativity. +An AND list has the form +.RS +.PP +\fIcommand1\fP \fB&&\fP \fIcommand2\fP +.RE +.PP +.I command2 +is executed if, and only if, +.I command1 +returns an exit status of zero. +.PP +An OR list has the form +.RS +.PP +\fIcommand1\fP \fB||\fP \fIcommand2\fP +.PP +.RE +.PP +.I command2 +is executed if and only if +.I 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. +.SS Compound Commands +.PP +A \fIcompound command\fP is one of the following. +In most cases a \fIlist\fP in a command's description may be separated from +the rest of the command by one or more newlines, and may be followed by a +newline in place of a semicolon. +.TP +(\fIlist\fP) +\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. +.TP +{ \fIlist\fP; } +\fIlist\fP is simply executed in the current shell environment. +\fIlist\fP must be terminated with a newline or semicolon. +This is known as a \fIgroup command\fP. +The return status is the exit status of +\fIlist\fP. +Note that unlike the metacharacters \fB(\fP and \fB)\fP, \fB{\fP and +\fB}\fP are \fIreserved words\fP and must occur where a reserved +word is permitted to be recognized. Since they do not cause a word +break, they must be separated from \fIlist\fP by whitespace or another +shell metacharacter. +.TP +((\fIexpression\fP)) +The \fIexpression\fP is evaluated according to the rules described +below under +.SM +.BR "ARITHMETIC EVALUATION" . +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 +\fBlet "\fIexpression\fP"\fR. +.TP +\fB[[\fP \fIexpression\fP \fB]]\fP +Return a status of 0 or 1 depending on the evaluation of +the conditional expression \fIexpression\fP. +Expressions are composed of the primaries described below under +.SM +.BR "CONDITIONAL EXPRESSIONS" . +Word splitting and pathname expansion are not performed on the words +between the \fB[[\fP and \fB]]\fP; tilde expansion, parameter and +variable expansion, arithmetic expansion, command substitution, process +substitution, and quote removal are performed. +Conditional operators such as \fB\-f\fP must be unquoted to be recognized +as primaries. +.if t .sp 0.5 +.if n .sp 1 +When used with \fB[[\fP, the \fB<\fP and \fB>\fP operators sort +lexicographically using the current locale. +.if t .sp 0.5 +.if n .sp 1 +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. +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 the quoted portion +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. +Any part of the pattern may be quoted to force the quoted portion +to be matched as a string. +Substrings matched by parenthesized subexpressions within the regular +expression are saved in the array variable +.SM +.BR BASH_REMATCH . +The element of +.SM +.B BASH_REMATCH +with index 0 is the portion of the string +matching the entire regular expression. +The element of +.SM +.B BASH_REMATCH +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 +.if n .sp 1 +.RS +.PD 0 +.TP +.B ( \fIexpression\fP ) +Returns the value of \fIexpression\fP. +This may be used to override the normal precedence of operators. +.TP +.B ! \fIexpression\fP +True if +.I expression +is false. +.TP +\fIexpression1\fP \fB&&\fP \fIexpression2\fP +True if both +.I expression1 +and +.I expression2 +are true. +.TP +\fIexpression1\fP \fB||\fP \fIexpression2\fP +True if either +.I expression1 +or +.I expression2 +is true. +.PD +.LP +The \fB&&\fP and \fB||\fP +operators do not evaluate \fIexpression2\fP if the value of +\fIexpression1\fP is sufficient to determine the return value of +the entire conditional expression. +.RE +.TP +\fBfor\fP \fIname\fP [ [ \fBin\fP [ \fIword ...\fP ] ] ; ] \fBdo\fP \fIlist\fP ; \fBdone\fP +The list of words following \fBin\fP is expanded, generating a list +of items. +The variable \fIname\fP is set to each element of this list +in turn, and \fIlist\fP is executed each time. +If the \fBin\fP \fIword\fP is omitted, the \fBfor\fP command executes +\fIlist\fP once for each positional parameter that is set (see +.SM +.B PARAMETERS +below). +The return status is the exit status of the last command that executes. +If the expansion of the items following \fBin\fP results in an empty +list, no commands are executed, and the return status is 0. +.TP +\fBfor\fP (( \fIexpr1\fP ; \fIexpr2\fP ; \fIexpr3\fP )) ; \fBdo\fP \fIlist\fP ; \fBdone\fP +First, the arithmetic expression \fIexpr1\fP is evaluated according +to the rules described below under +.SM +.BR "ARITHMETIC EVALUATION" . +The arithmetic expression \fIexpr2\fP is then evaluated repeatedly +until it evaluates to zero. +Each time \fIexpr2\fP evaluates to a non-zero value, \fIlist\fP is +executed and the arithmetic expression \fIexpr3\fP 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 \fIlist\fP +that is executed, or false if any of the expressions is invalid. +.TP +\fBselect\fP \fIname\fP [ \fBin\fP \fIword\fP ] ; \fBdo\fP \fIlist\fP ; \fBdone\fP +The list of words following \fBin\fP is expanded, generating a list +of items. The set of expanded words is printed on the standard +error, each preceded by a number. If the \fBin\fP +\fIword\fP is omitted, the positional parameters are printed (see +.SM +.B PARAMETERS +below). The +.SM +.B PS3 +prompt is then displayed and a line read from the standard input. +If the line consists of a number corresponding to one of +the displayed words, then the value of +.I name +is set to that word. If the line is empty, the words and prompt +are displayed again. If EOF is read, the command completes. Any +other value read causes +.I name +to be set to null. The line read is saved in the variable +.SM +.BR REPLY . +The +.I list +is executed after each selection until a +.B break +command is executed. +The exit status of +.B select +is the exit status of the last command executed in +.IR list , +or zero if no commands were executed. +.TP +\fBcase\fP \fIword\fP \fBin\fP [ [(] \fIpattern\fP [ \fB|\fP \fIpattern\fP ] \ +... ) \fIlist\fP ;; ] ... \fBesac\fP +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). +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. +If the \fB;;\fP operator is used, no subsequent matches are attempted after +the first pattern match. +Using \fB;&\fP in place of \fB;;\fP causes execution to continue with +the \fIlist\fP associated with the next set of patterns. +Using \fB;;&\fP in place of \fB;;\fP causes the shell to test the next +pattern list in the statement, if any, and execute any associated \fIlist\fP +on a successful match. +The exit status is zero if no +pattern matches. Otherwise, it is the exit status of the +last command executed in \fIlist\fP. +.TP +\fBif\fP \fIlist\fP; \fBthen\fP \fIlist;\fP \ +[ \fBelif\fP \fIlist\fP; \fBthen\fP \fIlist\fP; ] ... \ +[ \fBelse\fP \fIlist\fP; ] \fBfi\fP +The +.B if +.I list +is executed. If its exit status is zero, the +\fBthen\fP \fIlist\fP is executed. Otherwise, each \fBelif\fP +\fIlist\fP is executed in turn, and if its exit status is zero, +the corresponding \fBthen\fP \fIlist\fP is executed and the +command completes. Otherwise, the \fBelse\fP \fIlist\fP is +executed, if present. The exit status is the exit status of the +last command executed, or zero if no condition tested true. +.TP +\fBwhile\fP \fIlist-1\fP; \fBdo\fP \fIlist-2\fP; \fBdone\fP +.PD 0 +.TP +\fBuntil\fP \fIlist-1\fP; \fBdo\fP \fIlist-2\fP; \fBdone\fP +.PD +The \fBwhile\fP command continuously executes the list +\fIlist-2\fP as long as the last command in the list \fIlist-1\fP returns +an exit status of zero. The \fBuntil\fP command is identical +to the \fBwhile\fP command, except that the test is negated; +.I list-2 +is executed as long as the last command in +.I list-1 +returns a non-zero exit status. +The exit status of the \fBwhile\fP and \fBuntil\fP commands +is the exit status +of the last command executed in \fIlist-2\fP, or zero if +none was executed. +.SS Coprocesses +.PP +A \fIcoprocess\fP is a shell command preceded by the \fBcoproc\fP reserved +word. +A coprocess is executed asynchronously in a subshell, as if the command +had been terminated with the \fB&\fP control operator, with a two-way pipe +established between the executing shell and the coprocess. +.PP +The format for a coprocess is: +.RS +.PP +\fBcoproc\fP [\fINAME\fP] \fIcommand\fP [\fIredirections\fP] +.RE +.PP +This creates a coprocess named \fINAME\fP. +If \fINAME\fP is not supplied, the default name is \fBCOPROC\fP. +\fINAME\fP must not be supplied if \fIcommand\fP is a \fIsimple +command\fP (see above); otherwise, it is interpreted as the first word +of the simple command. +When the coproc is executed, the shell creates an array variable (see +.B Arrays +below) named \fINAME\fP in the context of the executing shell. +The standard output of +.I command +is connected via a pipe to a file descriptor in the executing shell, +and that file descriptor is assigned to \fINAME\fP[0]. +The standard input of +.I command +is connected via a pipe to a file descriptor in the executing shell, +and that file descriptor is assigned to \fINAME\fP[1]. +This pipe is established before any redirections specified by the +command (see +.SM +.B REDIRECTION +below). +The file descriptors can be utilized as arguments to shell commands +and redirections using standard word expansions. +The process ID of the shell spawned to execute the coprocess is +available as the value of the variable \fINAME\fP_PID. +The \fBwait\fP +builtin command may be used to wait for the coprocess to terminate. +.PP +The return status of a coprocess is the exit status of \fIcommand\fP. +.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 +\fIname\fP () \fIcompound\-command\fP [\fIredirection\fP] +.PD 0 +.TP +\fBfunction\fP \fIname\fP [()] \fIcompound\-command\fP [\fIredirection\fP] +.PD +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.) +.SH COMMENTS +In a non-interactive shell, or an interactive shell in which the +.B interactive_comments +option to the +.B shopt +builtin is enabled (see +.SM +.B "SHELL BUILTIN COMMANDS" +below), a word beginning with +.B # +causes that word and all remaining characters on that line to +be ignored. An interactive shell without the +.B interactive_comments +option enabled does not allow comments. The +.B interactive_comments +option is on by default in interactive shells. +.SH QUOTING +\fIQuoting\fP 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. +.PP +Each of the \fImetacharacters\fP listed above under +.SM +.B DEFINITIONS +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 +(see +.SM +.B HISTORY EXPANSION +below), the +\fIhistory expansion\fP character, usually \fB!\fP, must be quoted +to prevent history expansion. +.PP +There are three quoting mechanisms: the +.IR "escape character" , +single quotes, and double quotes. +.PP +A non-quoted backslash (\fB\e\fP) is the +.IR "escape character" . +It preserves the literal value of the next character that follows, +with the exception of . If a \fB\e\fP pair +appears, and the backslash is not itself quoted, the \fB\e\fP +is treated as a line continuation (that is, it is removed from the +input stream and effectively ignored). +.PP +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. +.PP +Enclosing characters in double quotes preserves the literal value +of all characters within the quotes, with the exception of +.BR $ , +.BR \` , +.BR \e , +and, when history expansion is enabled, +.BR ! . +The characters +.B $ +and +.B \` +retain their special meaning within double quotes. The backslash +retains its special meaning only when followed by one of the following +characters: +.BR $ , +.BR \` , +\^\fB"\fP\^, +.BR \e , +or +.BR . +A double quote may be quoted within double quotes by preceding it with +a backslash. +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 * +and +.B @ +have special meaning when in double +quotes (see +.SM +.B PARAMETERS +below). +.PP +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 specified by the ANSI C standard. Backslash escape sequences, if +present, are decoded as follows: +.RS +.PD 0 +.TP +.B \ea +alert (bell) +.TP +.B \eb +backspace +.TP +.B \ee +.TP +.B \eE +an escape character +.TP +.B \ef +form feed +.TP +.B \en +new line +.TP +.B \er +carriage return +.TP +.B \et +horizontal tab +.TP +.B \ev +vertical tab +.TP +.B \e\e +backslash +.TP +.B \e\(aq +single quote +.TP +.B \e\(dq +double quote +.TP +.B \e\fInnn\fP +the eight-bit character whose value is the octal value \fInnn\fP +(one to three digits) +.TP +.B \ex\fIHH\fP +the eight-bit character whose value is the hexadecimal value \fIHH\fP +(one or two hex digits) +.TP +.B \eu\fIHHHH\fP +the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value +\fIHHHH\fP (one to four hex digits) +.TP +.B \eU\fIHHHHHHHH\fP +the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value +\fIHHHHHHHH\fP (one to eight hex digits) +.TP +.B \ec\fIx\fP +a control-\fIx\fP character +.PD +.RE +.LP +The expanded result is single-quoted, as if the dollar sign had +not been present. +.PP +A double-quoted string preceded by a dollar sign (\fB$\fP\(dq\fIstring\fP\(dq) +will cause the string to be translated according to the current locale. +If the current locale is \fBC\fP or \fBPOSIX\fP, the dollar sign +is ignored. +If the string is translated and replaced, the replacement is +double-quoted. +.SH PARAMETERS +A +.I parameter +is an entity that stores values. +It can be a +.IR name , +a number, or one of the special characters listed below under +.BR "Special Parameters" . +A +.I variable +is a parameter denoted by a +.IR name . +A variable has a \fIvalue\fP and zero or more \fIattributes\fP. +Attributes are assigned using the +.B declare +builtin command (see +.B declare +below in +.SM +.BR "SHELL BUILTIN COMMANDS" ). +.PP +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 +.B unset +builtin command (see +.SM +.B SHELL BUILTIN COMMANDS +below). +.PP +A +.I variable +may be assigned to by a statement of the form +.RS +.PP +\fIname\fP=[\fIvalue\fP] +.RE +.PP +If +.I value +is not given, the variable is assigned the null string. All +.I values +undergo tilde expansion, parameter and variable expansion, +command substitution, arithmetic expansion, and quote +removal (see +.SM +.B EXPANSION +below). If the variable has its +.B integer +attribute set, then +.I value +is evaluated as an arithmetic expression even if the $((...)) expansion is +not used (see +.B "Arithmetic Expansion" +below). +Word splitting is not performed, with the exception +of \fB"$@"\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 , +.BR readonly , +and +.B local +builtin commands. +When in \fIposix mode\fP, these builtins may appear in a command after +one or more instances of the \fBcommand\fP builtin and retain these +assignment statement properties. +.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 \fIinteger\fP 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 +(for indexed arrays) or added as additional key\-value pairs in an +associative array. +When applied to a string-valued variable, \fIvalue\fP is expanded and +appended to the variable's value. +.SS Positional Parameters +.PP +A +.I 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 +.B set +builtin command. Positional parameters may not be assigned to +with assignment statements. The positional parameters are +temporarily replaced when a shell function is executed (see +.SM +.B FUNCTIONS +below). +.PP +When a positional parameter consisting of more than a single +digit is expanded, it must be enclosed in braces (see +.SM +.B EXPANSION +below). +.SS Special Parameters +.PP +The shell treats several parameters specially. These parameters may +only be referenced; assignment to them is not allowed. +.PD 0 +.TP +.B * +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 +.SM +.B IFS +special variable. That is, "\fB$*\fP" is equivalent +to "\fB$1\fP\fIc\fP\fB$2\fP\fIc\fP\fB...\fP", where +.I c +is the first character of the value of the +.SM +.B IFS +variable. If +.SM +.B IFS +is unset, the parameters are separated by spaces. +If +.SM +.B IFS +is null, the parameters are joined without intervening separators. +.TP +.B @ +Expands to the positional parameters, starting from one. When the +expansion occurs within double quotes, each parameter expands to a +separate word. That is, "\fB$@\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). +.TP +.B # +Expands to the number of positional parameters in decimal. +.TP +.B ? +Expands to the exit status of the most recently executed foreground +pipeline. +.TP +.B \- +Expands to the current option flags as specified upon invocation, +by the +.B set +builtin command, or those set by the shell itself +(such as the +.B \-i +option). +.TP +.B $ +Expands to the process ID of the shell. In a () subshell, it +expands to the process ID of the current shell, not the +subshell. +.TP +.B ! +Expands to the process ID of the most recently executed background +(asynchronous) command. +.TP +.B 0 +Expands to the name of the shell or shell script. This is set at +shell initialization. If +.B bash +is invoked with a file of commands, +.B $0 +is set to the name of that file. If +.B bash +is started with the +.B \-c +option, then +.B $0 +is set to the first argument after the string to be +executed, if one is present. Otherwise, it is set +to the file name used to invoke +.BR bash , +as given by argument zero. +.TP +.B _ +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 +currently being checked. +.PD +.SS Shell Variables +.PP +The following variables are set by the shell: +.PP +.PD 0 +.TP +.B BASH +Expands to the full file name used to invoke this instance of +.BR bash . +.TP +.B BASHOPTS +A colon-separated list of enabled shell options. Each word in +the list is a valid argument for the +.B \-s +option to the +.B shopt +builtin command (see +.SM +.B "SHELL BUILTIN COMMANDS" +below). The options appearing in +.SM +.B BASHOPTS +are those reported as +.I on +by \fBshopt\fP. +If this variable is in the environment when +.B bash +starts up, each shell option in the list will be enabled before +reading any startup files. +This variable is read-only. +.TP +.B BASHPID +Expands to the process ID of the current \fBbash\fP process. +This differs from \fB$$\fP under certain circumstances, such as subshells +that do not require \fBbash\fP to be re-initialized. +.TP +.B BASH_ALIASES +An associative array variable whose members correspond to the internal +list of aliases as maintained by the \fBalias\fP builtin. +Elements added to this array appear in the alias list; unsetting array +elements cause aliases to be removed from the alias list. +.TP +.B BASH_ARGC +An array variable whose values are the number of parameters in each +frame of the current \fBbash\fP 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 +.SM +.BR BASH_ARGC . +The shell sets +.SM +.B BASH_ARGC +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 \fBbash\fP +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 +.SM +.BR BASH_ARGV . +The shell sets +.SM +.B BASH_ARGV +only when in extended debugging mode +(see the description of the +.B extdebug +option to the +.B shopt +builtin below) +.TP +.B BASH_CMDS +An associative array variable whose members correspond to the internal +hash table of commands as maintained by the \fBhash\fP builtin. +Elements added to this array appear in the hash table; unsetting array +elements cause commands to be removed from the hash table. +.TP +.B 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. +.TP +.B BASH_EXECUTION_STRING +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 +where each corresponding member of +.SM +.B FUNCNAME +was invoked. +\fB${BASH_LINENO[\fP\fI$i\fP\fB]}\fP is the line number in the source +file (\fB${BASH_SOURCE[\fP\fI$i+1\fP\fB]}\fP) where +\fB${FUNCNAME[\fP\fI$i\fP\fB]}\fP was called +(or \fB${BASH_LINENO[\fP\fI$i-1\fP\fB]}\fP if referenced within another +shell function). +Use +.SM +.B LINENO +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 +where the corresponding shell function names in the +.SM +.B FUNCNAME +array variable are defined. +The shell function +\fB${FUNCNAME[\fP\fI$i\fP\fB]}\fP is defined in the file +\fB${BASH_SOURCE[\fP\fI$i\fP\fB]}\fP and called from +\fB${BASH_SOURCE[\fP\fI$i+1\fP\fB]}\fP. +.TP +.B BASH_SUBSHELL +Incremented by one within each subshell or subshell environment when +the shell begins executing in that environment. +The initial value is 0. +.TP +.B BASH_VERSINFO +A readonly array variable whose members hold version information for +this instance of +.BR bash . +The values assigned to the array members are as follows: +.sp .5 +.RS +.TP 24 +.B BASH_VERSINFO[\fR0\fP] +The major version number (the \fIrelease\fP). +.TP +.B BASH_VERSINFO[\fR1\fP] +The minor version number (the \fIversion\fP). +.TP +.B BASH_VERSINFO[\fR2\fP] +The patch level. +.TP +.B BASH_VERSINFO[\fR3\fP] +The build version. +.TP +.B BASH_VERSINFO[\fR4\fP] +The release status (e.g., \fIbeta1\fP). +.TP +.B BASH_VERSINFO[\fR5\fP] +The value of +.SM +.BR MACHTYPE . +.RE +.TP +.B BASH_VERSION +Expands to a string describing the version of this instance of +.BR bash . +.TP +.B COMP_CWORD +An index into \fB${COMP_WORDS}\fP of the word containing the current +cursor position. +This variable is available only in shell functions invoked by the +programmable completion facilities (see \fBProgrammable Completion\fP +below). +.TP +.B COMP_KEY +The key (or final key of a key sequence) used to invoke the current +completion function. +.TP +.B COMP_LINE +The current command line. +This variable is available only in shell functions and external +commands invoked by the +programmable completion facilities (see \fBProgrammable Completion\fP +below). +.TP +.B COMP_POINT +The index of the current cursor position relative to the beginning of +the current command. +If the current cursor position is at the end of the current command, +the value of this variable is equal to \fB${#COMP_LINE}\fP. +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_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 \fBreadline\fP library treats as word +separators when performing word completion. +If +.SM +.B COMP_WORDBREAKS +is unset, it loses its special properties, even if it is +subsequently reset. +.TP +.B COMP_WORDS +An array variable (see \fBArrays\fP below) consisting of the individual +words in the current command line. +The line is split into words as \fBreadline\fP would split it, using +.SM +.B COMP_WORDBREAKS +as described above. +This variable is available only in shell functions invoked by the +programmable completion facilities (see \fBProgrammable Completion\fP +below). +.TP +.B COPROC +An array variable (see \fBArrays\fP below) created to hold the file descriptors +for output from and input to an unnamed coprocess (see \fBCoprocesses\fP +above). +.TP +.B DIRSTACK +An array variable (see +.B Arrays +below) containing the current contents of the directory stack. +Directories appear in the stack in the order they are displayed by the +.B dirs +builtin. +Assigning to members of this array variable may be used to modify +directories already in the stack, but the +.B pushd +and +.B popd +builtins must be used to add and remove directories. +Assignment to this variable will not change the current directory. +If +.SM +.B DIRSTACK +is unset, it loses its special properties, even if it is +subsequently reset. +.TP +.B EUID +Expands to the effective user ID of the current user, initialized at +shell startup. This variable is readonly. +.TP +.B 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 (the one with the highest index) is +.if t \f(CW"main"\fP. +.if n "main". +This variable exists only when a shell function is executing. +Assignments to +.SM +.B FUNCNAME +have no effect and return an error status. +If +.SM +.B FUNCNAME +is unset, it loses its special properties, even if it is +subsequently reset. +.if t .sp 0.5 +.if n .sp 1 +This variable can be used with \fBBASH_LINENO\fP and \fBBASH_SOURCE\fP. +Each element of \fBFUNCNAME\fP has corresponding elements in +\fBBASH_LINENO\fP and \fBBASH_SOURCE\fP to describe the call stack. +For instance, \fB${FUNCNAME[\fP\fI$i\fP\fB]}\fP was called from the file +\fB${BASH_SOURCE[\fP\fI$i+1\fP\fB]}\fP at line number +\fB${BASH_LINENO[\fP\fI$i\fP\fB]}\fP. +The \fBcaller\fP builtin displays the current call stack using this +information. +.TP +.B GROUPS +An array variable containing the list of groups of which the current +user is a member. +Assignments to +.SM +.B GROUPS +have no effect and return an error status. +If +.SM +.B GROUPS +is unset, it loses its special properties, even if it is +subsequently reset. +.TP +.B HISTCMD +The history number, or index in the history list, of the current +command. +If +.SM +.B HISTCMD +is unset, it loses its special properties, even if it is +subsequently reset. +.TP +.B HOSTNAME +Automatically set to the name of the current host. +.TP +.B HOSTTYPE +Automatically set to a string that uniquely +describes the type of machine on which +.B bash +is executing. +The default is system-dependent. +.TP +.B LINENO +Each time this parameter is referenced, the shell substitutes +a decimal number representing the current sequential line number +(starting with 1) within a script or function. When not in a +script or function, the value substituted is not guaranteed to +be meaningful. +If +.SM +.B LINENO +is unset, it loses its special properties, even if it is +subsequently reset. +.TP +.B MACHTYPE +Automatically set to a string that fully describes the system +type on which +.B bash +is executing, in the standard GNU \fIcpu-company-system\fP format. +The default is system-dependent. +.TP +.B MAPFILE +An array variable (see \fBArrays\fP below) created to hold the text +read by the \fBmapfile\fP builtin when no variable name is supplied. +.TP +.B OLDPWD +The previous working directory as set by the +.B cd +command. +.TP +.B OPTARG +The value of the last option argument processed by the +.B getopts +builtin command (see +.SM +.B SHELL BUILTIN COMMANDS +below). +.TP +.B OPTIND +The index of the next argument to be processed by the +.B getopts +builtin command (see +.SM +.B SHELL BUILTIN COMMANDS +below). +.TP +.B OSTYPE +Automatically set to a string that +describes the operating system on which +.B bash +is executing. +The default is system-dependent. +.TP +.B PIPESTATUS +An array variable (see +.B Arrays +below) containing a list of exit status values from the processes +in the most-recently-executed foreground pipeline (which may +contain only a single command). +.TP +.B PPID +The process ID of the shell's parent. This variable is readonly. +.TP +.B PWD +The current working directory as set by the +.B cd +command. +.TP +.B RANDOM +Each time this parameter is referenced, a random integer between +0 and 32767 is +generated. The sequence of random numbers may be initialized by assigning +a value to +.SM +.BR RANDOM . +If +.SM +.B RANDOM +is unset, it loses its special properties, even if it is +subsequently reset. +.TP +.B READLINE_LINE +The contents of the +.B readline +line buffer, for use with +.if t \f(CWbind -x\fP +.if n "bind -x" +(see +.SM +.B "SHELL BUILTIN COMMANDS" +below). +.TP +.B READLINE_POINT +The position of the insertion point in the +.B readline +line buffer, for use with +.if t \f(CWbind -x\fP +.if n "bind -x" +(see +.SM +.B "SHELL BUILTIN COMMANDS" +below). +.TP +.B REPLY +Set to the line of input read by the +.B read +builtin command when no arguments are supplied. +.TP +.B SECONDS +Each time this parameter is +referenced, the number of seconds since shell invocation is returned. If a +value is assigned to +.SM +.BR SECONDS , +the value returned upon subsequent +references is +the number of seconds since the assignment plus the value assigned. +If +.SM +.B SECONDS +is unset, it loses its special properties, even if it is +subsequently reset. +.TP +.B SHELLOPTS +A colon-separated list of enabled shell options. Each word in +the list is a valid argument for the +.B \-o +option to the +.B set +builtin command (see +.SM +.B "SHELL BUILTIN COMMANDS" +below). The options appearing in +.SM +.B SHELLOPTS +are those reported as +.I on +by \fBset \-o\fP. +If this variable is in the environment when +.B bash +starts up, each shell option in the list will be enabled before +reading any startup files. +This variable is read-only. +.TP +.B SHLVL +Incremented by one each time an instance of +.B bash +is started. +.TP +.B UID +Expands to the user ID of the current user, initialized at shell startup. +This variable is readonly. +.PD +.PP +The following variables are used by the shell. In some cases, +.B bash +assigns a default value to a variable; these cases are noted +below. +.PP +.PD 0 +.TP +.B BASH_ENV +If this parameter is set when \fBbash\fP is executing a shell script, +its value is interpreted as a filename containing commands to +initialize the shell, as in +.IR ~/.bashrc . +The value of +.SM +.B BASH_ENV +is subjected to parameter expansion, command substitution, and arithmetic +expansion before being interpreted as a file name. +.SM +.B PATH +is not used to search for the resultant file name. +.TP +.B BASH_XTRACEFD +If set to an integer corresponding to a valid file descriptor, \fBbash\fP +will write the trace output generated when +.if t \f(CWset -x\fP +.if n \fIset -x\fP +is enabled to that file descriptor. +The file descriptor is closed when +.SM +.B BASH_XTRACEFD +is unset or assigned a new value. +Unsetting +.SM +.B BASH_XTRACEFD +or assigning it the empty string causes the +trace output to be sent to the standard error. +Note that setting +.SM +.B BASH_XTRACEFD +to 2 (the standard error file +descriptor) and then unsetting it will result in the standard error +being closed. +.TP +.B CDPATH +The search path for the +.B cd +command. +This is a colon-separated list of directories in which the shell looks +for destination directories specified by the +.B cd +command. +A sample value is +.if t \f(CW".:~:/usr"\fP. +.if n ".:~:/usr". +.TP +.B COLUMNS +Used by the \fBselect\fP compound command to determine the terminal width +when printing selection lists. Automatically set in an interactive shell +upon receipt of a +.SM +.BR SIGWINCH . +.TP +.B COMPREPLY +An array variable from which \fBbash\fP reads the possible completions +generated by a shell function invoked by the programmable completion +facility (see \fBProgrammable Completion\fP below). +.TP +.B EMACS +If \fBbash\fP finds this variable in the environment when the shell starts +with value +.if t \f(CWt\fP, +.if n "t", +it assumes that the shell is running in an Emacs shell buffer and disables +line editing. +.TP +.B ENV +Similar to +.SM +.BR BASH_ENV ; +used when the shell is invoked in POSIX mode. +.TP +.B FCEDIT +The default editor for the +.B fc +builtin command. +.TP +.B FIGNORE +A colon-separated list of suffixes to ignore when performing +filename completion (see +.SM +.B READLINE +below). +A filename whose suffix matches one of the entries in +.SM +.B FIGNORE +is excluded from the list of matched filenames. +A sample value is +.if t \f(CW".o:~"\fP. +.if n ".o:~". +.TP +.B FUNCNEST +If set to a numeric value greater than 0, defines a maximum function +nesting level. Function invocations that exceed this nesting level +will cause the current command to abort. +.TP +.B GLOBIGNORE +A colon-separated list of patterns defining the set of filenames to +be ignored by pathname expansion. +If a filename matched by a pathname expansion pattern also matches one +of the patterns in +.SM +.BR GLOBIGNORE , +it is removed from the list of matches. +.TP +.B HISTCONTROL +A colon-separated list of values controlling how commands are saved on +the history list. +If the list of values includes +.IR ignorespace , +lines which begin with a +.B space +character are not saved in the history list. +A value of +.I ignoredups +causes lines matching the previous history entry to not be saved. +A value of +.I ignoreboth +is shorthand for \fIignorespace\fP and \fIignoredups\fP. +A value of +.IR 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 +.SM +.B 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 +.SM +.BR 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 +.SM +.BR HISTCONTROL . +.TP +.B HISTFILE +The name of the file in which command history is saved (see +.SM +.B HISTORY +below). The default value is \fI~/.bash_history\fP. If unset, the +command history is not saved when an interactive shell exits. +.TP +.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, 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 +.B 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 +`\fB*\fP' is appended). Each pattern is tested against the line +after the checks specified by +.SM +.B HISTCONTROL +are applied. +In addition to the normal shell pattern matching characters, `\fB&\fP' +matches the previous history line. `\fB&\fP' 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 +.SM +.BR HISTIGNORE . +.TP +.B HISTSIZE +The number of commands to remember in the command history (see +.SM +.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. +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 +\fBcd\fP builtin command. +The value of this variable is also used when performing tilde expansion. +.TP +.B HOSTFILE +Contains the name of a file in the same format as +.FN /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, +.B bash +adds the contents of the new file to the existing list. +If +.SM +.B HOSTFILE +is set, but has no value, or does not name a readable file, +\fBbash\fP attempts to read +.FN /etc/hosts +to obtain the list of possible hostname completions. +When +.SM +.B HOSTFILE +is unset, the hostname list is cleared. +.TP +.B IFS +The +.I Internal Field Separator +that is used +for word splitting after expansion and to +split lines into words with the +.B read +builtin command. The default value is +``''. +.TP +.B IGNOREEOF +Controls the +action of an interactive shell on receipt of an +.SM +.B EOF +character as the sole input. If set, the value is the number of +consecutive +.SM +.B EOF +characters which must be +typed as the first characters on an input line before +.B bash +exits. If the variable exists but does not have a numeric value, or +has no value, the default value is 10. If it does not exist, +.SM +.B EOF +signifies the end of input to the shell. +.TP +.B INPUTRC +The filename for the +.B readline +startup file, overriding the default of +.FN ~/.inputrc +(see +.SM +.B READLINE +below). +.TP +.B LANG +Used to determine the locale category for any category not specifically +selected with a variable starting with \fBLC_\fP. +.TP +.B LC_ALL +This variable overrides the value of +.SM +.B LANG +and any other +\fBLC_\fP variable specifying a locale category. +.TP +.B LC_COLLATE +This variable determines the collation order used when sorting the +results of pathname expansion, and determines the behavior of range +expressions, equivalence classes, and collating sequences within +pathname expansion and pattern matching. +.TP +.B LC_CTYPE +This variable determines the interpretation of characters and the +behavior of character classes within pathname expansion and pattern +matching. +.TP +.B LC_MESSAGES +This variable determines the locale used to translate double-quoted +strings preceded by a \fB$\fP. +.TP +.B LC_NUMERIC +This variable determines the locale category used for number formatting. +.TP +.B LINES +Used by the \fBselect\fP compound command to determine the column length +for printing selection lists. Automatically set by an interactive shell +upon receipt of a +.SM +.BR SIGWINCH . +.TP +.B MAIL +If this parameter is set to a file or directory name and the +.SM +.B MAILPATH +variable is not set, +.B bash +informs the user of the arrival of mail in the specified file or +Maildir-format directory. +.TP +.B MAILCHECK +Specifies how +often (in seconds) +.B bash +checks for mail. The default is 60 seconds. When it is time to check +for mail, the shell does so before displaying the primary prompt. +If this variable is unset, or set to a value that is not a number +greater than or equal to zero, the shell disables mail checking. +.TP +.B MAILPATH +A colon-separated list of file names to be checked for mail. +The message to be printed when mail arrives in a particular file +may be specified by separating the file name from the message with a `?'. +When used in the text of the message, \fB$_\fP expands to the name of +the current mailfile. +Example: +.RS +.PP +\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 +mail files that it uses is system dependent (e.g., /var/mail/\fB$USER\fP). +.RE +.TP +.B OPTERR +If set to the value 1, +.B bash +displays error messages generated by the +.B getopts +builtin command (see +.SM +.B SHELL BUILTIN COMMANDS +below). +.SM +.B OPTERR +is initialized to 1 each time the shell is invoked or a shell +script is executed. +.TP +.B PATH +The search path for commands. It +is a colon-separated list of directories in which +the shell looks for commands (see +.SM +.B COMMAND EXECUTION +below). +A zero-length (null) directory name in the value of +.SM +.B PATH +indicates the current directory. +A null directory name may appear as two adjacent colons, or as an initial +or trailing colon. +The default path is system-dependent, +and is set by the administrator who installs +.BR bash . +A common value is +.if t \f(CW/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin\fP. +.if n ``/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin''. +.TP +.B POSIXLY_CORRECT +If this variable is in the environment when \fBbash\fP starts, the shell +enters \fIposix mode\fP before reading the startup files, as if the +.B \-\-posix +invocation option had been supplied. If it is set while the shell is +running, \fBbash\fP enables \fIposix mode\fP, as if the command +.if t \f(CWset -o posix\fP +.if n \fIset -o posix\fP +had been executed. +.TP +.B PROMPT_COMMAND +If set, the value is executed as a command prior to issuing each primary +prompt. +.TP +.B PROMPT_DIRTRIM +If set to a number greater than zero, the value is used as the number of +trailing directory components to retain when expanding the \fB\ew\fP and +\fB\eW\fP prompt string escapes (see +.SM +.B PROMPTING +below). Characters removed are replaced with an ellipsis. +.TP +.B PS1 +The value of this parameter is expanded (see +.SM +.B PROMPTING +below) and used as the primary prompt string. The default value is +``\fB\es\-\ev\e$ \fP''. +.TP +.B PS2 +The value of this parameter is expanded as with +.SM +.B PS1 +and used as the secondary prompt string. The default is +``\fB> \fP''. +.TP +.B PS3 +The value of this parameter is used as the prompt for the +.B select +command (see +.SM +.B SHELL GRAMMAR +above). +.TP +.B PS4 +The value of this parameter is expanded as with +.SM +.B PS1 +and the value is printed before each command +.B bash +displays during an execution trace. The first character of +.SM +.B PS4 +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 +.B time +reserved word should be displayed. +The \fB%\fP 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. +.sp .5 +.RS +.PD 0 +.TP 10 +.B %% +A literal \fB%\fP. +.TP +.B %[\fIp\fP][l]R +The elapsed time in seconds. +.TP +.B %[\fIp\fP][l]U +The number of CPU seconds spent in user mode. +.TP +.B %[\fIp\fP][l]S +The number of CPU seconds spent in system mode. +.TP +.B %P +The CPU percentage, computed as (%U + %S) / %R. +.PD +.RE +.IP +The optional \fIp\fP is a digit specifying the \fIprecision\fP, +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 \fIp\fP greater than 3 are changed to 3. +If \fIp\fP is not specified, the value 3 is used. +.IP +The optional \fBl\fP specifies a longer format, including +minutes, of the form \fIMM\fPm\fISS\fP.\fIFF\fPs. +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$\(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. +.PD 0 +.TP +.B TMOUT +If set to a value greater than zero, +.SM +.B TMOUT +is treated as the +default timeout for the \fBread\fP builtin. +The \fBselect\fP command terminates if input does not arrive +after +.SM +.B 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. +.B Bash +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 +commands without redirections are treated as candidates for resumption +of an existing stopped job. There is no ambiguity allowed; if there is +more than one job beginning with the string typed, the job most recently +accessed is selected. The +.I name +of a stopped job, in this context, is the command line used to +start it. +If set to the value +.IR exact , +the string supplied must match the name of a stopped job exactly; +if set to +.IR substring , +the string supplied needs to match a substring of the name of a +stopped job. The +.I substring +value provides functionality analogous to the +.B %? +job identifier (see +.SM +.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 \fB%\fP\fIstring\fP job identifier. +.TP +.B histchars +The two or three characters which control history expansion +and tokenization (see +.SM +.B HISTORY EXPANSION +below). The first character is the \fIhistory expansion\fP character, +the character which signals the start of a history +expansion, normally `\fB!\fP'. +The second character is the \fIquick substitution\fP +character, which is used as shorthand for re-running the previous +command entered, substituting one string for another in the command. +The default is `\fB^\fP'. +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, normally `\fB#\fP'. 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. +.PD +.SS Arrays +.B Bash +provides one-dimensional indexed and associative array variables. +Any variable may be used as an indexed array; the +.B 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. +Indexed arrays are referenced using integers (including arithmetic +expressions) and are zero-based; associative arrays are referenced +using arbitrary strings. +.PP +An indexed array is created automatically if any variable is assigned to +using the syntax \fIname\fP[\fIsubscript\fP]=\fIvalue\fP. The +.I subscript +is treated as an arithmetic expression that must evaluate to a number. +To explicitly declare an indexed array, use +.B declare \-a \fIname\fP +(see +.SM +.B SHELL BUILTIN COMMANDS +below). +.B declare \-a \fIname\fP[\fIsubscript\fP] +is also accepted; the \fIsubscript\fP is ignored. +.PP +Associative arrays are created using +.BR "declare \-A \fIname\fP" . +.PP +Attributes may be +specified for an array variable using the +.B declare +and +.B readonly +builtins. Each attribute applies to all members of an array. +.PP +Arrays are assigned to using compound assignments of the form +\fIname\fP=\fB(\fPvalue\fI1\fP ... value\fIn\fP\fB)\fP, where each +\fIvalue\fP is of the form [\fIsubscript\fP]=\fIstring\fP. +Indexed array assignments do not require the bracket and subscript. +When assigning to indexed arrays, if the optional brackets and subscript +are 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. +.PP +When assigning to an associative array, the subscript is required. +.PP +This syntax is also accepted by the +.B declare +builtin. Individual array elements may be assigned to using the +\fIname\fP[\fIsubscript\fP]=\fIvalue\fP syntax introduced above. +.PP +Any element of an array may be referenced using +${\fIname\fP[\fIsubscript\fP]}. The braces are required to avoid +conflicts with pathname expansion. If +\fIsubscript\fP is \fB@\fP or \fB*\fP, the word expands to +all members of \fIname\fP. These subscripts differ only when the +word appears within double quotes. If the word is double-quoted, +${\fIname\fP[*]} expands to a single +word with the value of each array member separated by the first +character of the +.SM +.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. +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). ${#\fIname\fP[\fIsubscript\fP]} expands to the length of +${\fIname\fP[\fIsubscript\fP]}. If \fIsubscript\fP is \fB*\fP or +\fB@\fP, the expansion is the number of elements in the array. +Referencing an array variable without a subscript is equivalent to +referencing the array with a subscript of 0. +If the +.I subscript +used to reference an element of an indexed array +evaluates to a number less than zero, it is used as +an offset from one greater than the array's maximum index (so a subcript +of -1 refers to the last element of the array). +.PP +An array variable is considered set if a subscript has been assigned a +value. The null string is a valid value. +.PP +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 pathname +expansion. +\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. +.PP +The +.BR declare , +.BR local , +and +.B readonly +builtins each accept a +.B \-a +option to specify an indexed array and a +.B \-A +option to specify an associative array. +If both options are supplied, +.B \-A +takes precedence. +The +.B read +builtin accepts a +.B \-a +option to assign a list of words read from the standard input +to an array. The +.B set +and +.B declare +builtins display array values in a way that allows them to be +reused as assignments. +.SH EXPANSION +Expansion is performed on the command line after it has been split into +words. There are seven kinds of expansion performed: +.IR "brace expansion" , +.IR "tilde expansion" , +.IR "parameter and variable expansion" , +.IR "command substitution" , +.IR "arithmetic expansion" , +.IR "word splitting" , +and +.IR "pathname expansion" . +.PP +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 pathname +expansion. +.PP +On systems that can support it, there is an additional expansion +available: \fIprocess substitution\fP. +.PP +Only brace expansion, word splitting, and pathname 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 +"\fB$@\fP" and "\fB${\fP\fIname\fP\fB[@]}\fP" +as explained above (see +.SM +.BR PARAMETERS ). +.SS Brace Expansion +.PP +.I "Brace expansion" +is a mechanism by which arbitrary strings +may be generated. This mechanism is similar to +\fIpathname expansion\fP, but the filenames generated +need not exist. Patterns to be brace expanded take +the form of an optional +.IR preamble , +followed by either a series of comma-separated strings or +a sequence expression between a pair of braces, followed by +an optional +.IR 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. +.PP +Brace expansions may be nested. The results of each expanded +string are not sorted; left to right order is preserved. +For example, a\fB{\fPd,c,b\fB}\fPe expands into `ade ace abe'. +.PP +A sequence expression takes the form +\fB{\fP\fIx\fP\fB..\fP\fIy\fP\fB[..\fP\fIincr\fP\fB]}\fP, +where \fIx\fP and \fIy\fP are either integers or single characters, +and \fIincr\fP, an optional increment, is an integer. +When integers are supplied, the expression expands to each number between +\fIx\fP and \fIy\fP, inclusive. +Supplied integers may be prefixed with \fI0\fP to force each term to have the +same width. When either \fIx\fP or \fPy\fP begins with a zero, the shell +attempts to force all generated terms to contain the same number of digits, +zero-padding where necessary. +When characters are supplied, the expression expands to each character +lexicographically between \fIx\fP and \fIy\fP, inclusive. Note that +both \fIx\fP and \fIy\fP must be of the same type. +When the increment is supplied, it is used as the difference between +each term. The default increment is 1 or -1 as appropriate. +.PP +Brace expansion is performed before any other expansions, +and any characters special to other expansions are preserved +in the result. It is strictly textual. +.B Bash +does not apply any syntactic interpretation to the context of the +expansion or the text between the braces. +.PP +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 \fB{\fP or \fB,\fP may be quoted with a backslash to prevent its +being considered part of a brace expression. +To avoid conflicts with parameter expansion, the string \fB${\fP +is not considered eligible for brace expansion. +.PP +This construct is typically used as shorthand when the common +prefix of the strings to be generated is longer than in the +above example: +.RS +.PP +mkdir /usr/local/src/bash/{old,new,dist,bugs} +.RE +or +.RS +chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}} +.RE +.PP +Brace expansion introduces a slight incompatibility with +historical versions of +.BR sh . +.B sh +does not treat opening or closing braces specially when they +appear as part of a word, and preserves them in the output. +.B Bash +removes braces from words as a consequence of brace +expansion. For example, a word entered to +.B sh +as \fIfile{1,2}\fP +appears identically in the output. The same word is +output as +.I file1 file2 +after expansion by +.BR bash . +If strict compatibility with +.B sh +is desired, start +.B bash +with the +.B +B +option or disable brace expansion with the +.B +B +option to the +.B set +command (see +.SM +.B SHELL BUILTIN COMMANDS +below). +.SS Tilde Expansion +.PP +If a word begins with an unquoted tilde character (`\fB~\fP'), all of +the characters preceding the first unquoted slash (or all characters, +if there is no unquoted slash) are considered a \fItilde-prefix\fP. +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 \fIlogin name\fP. +If this login name is the null string, the tilde is replaced with the +value of the shell parameter +.SM +.BR HOME . +If +.SM +.B 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. +.PP +If the tilde-prefix is a `~+', the value of the shell variable +.SM +.B PWD +replaces the tilde-prefix. +If the tilde-prefix is a `~\-', the value of the shell variable +.SM +.BR OLDPWD , +if it is set, is substituted. +If the characters following the tilde in the tilde-prefix consist +of a number \fIN\fP, 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 +.B dirs +builtin invoked with the tilde-prefix as an argument. +If the characters following the tilde in the tilde-prefix consist of a +number without a leading `+' or `\-', `+' is assumed. +.PP +If the login name is invalid, or the tilde expansion fails, the word +is unchanged. +.PP +Each variable assignment is checked for unquoted tilde-prefixes immediately +following a +.B : +or the first +.BR = . +In these cases, tilde expansion is also performed. +Consequently, one may use file names with tildes in assignments to +.SM +.BR PATH , +.SM +.BR MAILPATH , +and +.SM +.BR CDPATH , +and the shell assigns the expanded value. +.SS Parameter Expansion +.PP +The `\fB$\fP' 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. +.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 parameter +expansion. +.PP +.PD 0 +.TP +${\fIparameter\fP} +The value of \fIparameter\fP is substituted. The braces are required +when +.I parameter +is a positional parameter with more than one digit, +or when +.I parameter +is followed by a character which is not to be +interpreted as part of its name. +.PD +.PP +If the first character of \fIparameter\fP is an exclamation point (\fB!\fP), +a level of variable indirection is introduced. +\fBBash\fP uses the value of the variable formed from the rest of +\fIparameter\fP 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 \fIparameter\fP itself. +This is known as \fIindirect expansion\fP. +The exceptions to this are the expansions of ${\fB!\fP\fIprefix\fP\fB*\fP} and +${\fB!\fP\fIname\fP[\fI@\fP]} described below. +The exclamation point must immediately follow the left brace in order to +introduce indirection. +.PP +In each of the cases below, \fIword\fP is subject to tilde expansion, +parameter expansion, command substitution, and arithmetic expansion. +.PP +When not performing substring expansion, using the forms documented below, +\fBbash\fP tests for a parameter that is unset or null. Omitting the colon +results in a test only for a parameter that is unset. +.PP +.PD 0 +.TP +${\fIparameter\fP\fB:\-\fP\fIword\fP} +\fBUse Default Values\fP. If +.I parameter +is unset or null, the expansion of +.I word +is substituted. Otherwise, the value of +.I parameter +is substituted. +.TP +${\fIparameter\fP\fB:=\fP\fIword\fP} +\fBAssign Default Values\fP. +If +.I parameter +is unset or null, the expansion of +.I word +is assigned to +.IR parameter . +The value of +.I parameter +is then substituted. Positional parameters and special parameters may +not be assigned to in this way. +.TP +${\fIparameter\fP\fB:?\fP\fIword\fP} +\fBDisplay Error if Null or Unset\fP. +If +.I parameter +is null or unset, the expansion of \fIword\fP (or a message to that effect +if +.I word +is not present) is written to the standard error and the shell, if it +is not interactive, exits. Otherwise, the value of \fIparameter\fP is +substituted. +.TP +${\fIparameter\fP\fB:+\fP\fIword\fP} +\fBUse Alternate Value\fP. +If +.I parameter +is null or unset, nothing is substituted, otherwise the expansion of +.I word +is substituted. +.TP +${\fIparameter\fP\fB:\fP\fIoffset\fP} +.PD 0 +.TP +${\fIparameter\fP\fB:\fP\fIoffset\fP\fB:\fP\fIlength\fP} +.PD +\fBSubstring Expansion\fP. +Expands to up to \fIlength\fP characters of \fIparameter\fP +starting at the character specified by \fIoffset\fP. +If \fIlength\fP is omitted, expands to the substring of +\fIparameter\fP starting at the character specified by \fIoffset\fP. +\fIlength\fP and \fIoffset\fP are arithmetic expressions (see +.SM +.B +ARITHMETIC EVALUATION +below). +If \fIoffset\fP evaluates to a number less than zero, the value +is used as an offset from the end of the value of \fIparameter\fP. +If \fIlength\fP evaluates to a number less than zero, and \fIparameter\fP +is not \fB@\fP and not an indexed or associative array, it is interpreted +as an offset from the end of the value of \fIparameter\fP rather than +a number of characters, and the expansion is the characters between the +two offsets. +If \fIparameter\fP is \fB@\fP, the result is \fIlength\fP positional +parameters beginning at \fIoffset\fP. +If \fIparameter\fP is an indexed array name subscripted 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. +Substring expansion applied to an associative array produces undefined +results. +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 \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 +.TP +${\fB!\fP\fIprefix\fP\fB@\fP} +.PD +\fBNames matching prefix\fP. +Expands to the names of variables whose names begin with \fIprefix\fP, +separated by the first character of the +.SM +.B IFS +special variable. +When \fI@\fP is used and the expansion appears within double quotes, each +variable name expands to a separate word. +.TP +${\fB!\fP\fIname\fP[\fI@\fP]} +.PD 0 +.TP +${\fB!\fP\fIname\fP[\fI*\fP]} +.PD +\fBList of array keys\fP. +If \fIname\fP is an array variable, expands to the list of array indices +(keys) assigned in \fIname\fP. +If \fIname\fP is not an array, expands to 0 if \fIname\fP is set and null +otherwise. +When \fI@\fP is used and the expansion appears within double quotes, each +key expands to a separate word. +.TP +${\fB#\fP\fIparameter\fP} +\fBParameter length\fP. +The length in characters of the value of \fIparameter\fP is substituted. +If +.I parameter +is +.B * +or +.BR @ , +the value substituted is the number of positional parameters. +If +.I parameter +is an array name subscripted by +.B * +or +.BR @ , +the value substituted is the number of elements in the array. +.TP +${\fIparameter\fP\fB#\fP\fIword\fP} +.PD 0 +.TP +${\fIparameter\fP\fB##\fP\fIword\fP} +.PD +\fBRemove matching prefix pattern\fP. +The +.I word +is expanded to produce a pattern just as in pathname +expansion. If the pattern matches the beginning of +the value of +.IR parameter , +then the result of the expansion is the expanded value of +.I parameter +with the shortest matching pattern (the ``\fB#\fP'' case) or the +longest matching pattern (the ``\fB##\fP'' case) deleted. +If +.I parameter +is +.B @ +or +.BR * , +the pattern removal operation is applied to each positional +parameter in turn, and the expansion is the resultant list. +If +.I parameter +is an array variable subscripted with +.B @ +or +.BR * , +the pattern removal operation is applied to each member of the +array in turn, and the expansion is the resultant list. +.TP +${\fIparameter\fP\fB%\fP\fIword\fP} +.PD 0 +.TP +${\fIparameter\fP\fB%%\fP\fIword\fP} +.PD +\fBRemove matching suffix pattern\fP. +The \fIword\fP is expanded to produce a pattern just as in +pathname expansion. +If the pattern matches a trailing portion of the expanded value of +.IR parameter , +then the result of the expansion is the expanded value of +.I parameter +with the shortest matching pattern (the ``\fB%\fP'' case) or the +longest matching pattern (the ``\fB%%\fP'' case) deleted. +If +.I parameter +is +.B @ +or +.BR * , +the pattern removal operation is applied to each positional +parameter in turn, and the expansion is the resultant list. +If +.I parameter +is an array variable subscripted with +.B @ +or +.BR * , +the pattern removal operation is applied to each member of the +array in turn, and the expansion is the resultant list. +.TP +${\fIparameter\fP\fB/\fP\fIpattern\fP\fB/\fP\fIstring\fP} +\fBPattern substitution\fP. +The \fIpattern\fP is expanded to produce a pattern just as in +pathname expansion. +\fIParameter\fP is expanded and the longest match of \fIpattern\fP +against its value is replaced with \fIstring\fP. +If \fIpattern\fP begins with \fB/\fP, all matches of \fIpattern\fP are +replaced with \fIstring\fP. Normally only the first match is replaced. +If \fIpattern\fP begins with \fB#\fP, it must match at the beginning +of the expanded value of \fIparameter\fP. +If \fIpattern\fP begins with \fB%\fP, it must match at the end +of the expanded value of \fIparameter\fP. +If \fIstring\fP is null, matches of \fIpattern\fP are deleted +and the \fB/\fP following \fIpattern\fP may be omitted. +If +.I parameter +is +.B @ +or +.BR * , +the substitution operation is applied to each positional +parameter in turn, and the expansion is the resultant list. +If +.I parameter +is an array variable subscripted with +.B @ +or +.BR * , +the substitution operation is applied to each member of the +array in turn, and the expansion is the resultant list. +.TP +${\fIparameter\fP\fB^\fP\fIpattern\fP} +.PD 0 +.TP +${\fIparameter\fP\fB^^\fP\fIpattern\fP} +.TP +${\fIparameter\fP\fB,\fP\fIpattern\fP} +.TP +${\fIparameter\fP\fB,,\fP\fIpattern\fP} +.PD +\fBCase modification\fP. +This expansion modifies the case of alphabetic characters in \fIparameter\fP. +The \fIpattern\fP is expanded to produce a pattern just as in +pathname expansion. +The \fB^\fP operator converts lowercase letters matching \fIpattern\fP +to uppercase; the \fB,\fP operator converts matching uppercase letters +to lowercase. +The \fB^^\fP and \fB,,\fP expansions convert each matched character in the +expanded value; the \fB^\fP and \fB,\fP expansions match and convert only +the first character in the expanded value. +If \fIpattern\fP is omitted, it is treated like a \fB?\fP, which matches +every character. +If +.I parameter +is +.B @ +or +.BR * , +the case modification operation is applied to each positional +parameter in turn, and the expansion is the resultant list. +If +.I parameter +is an array variable subscripted with +.B @ +or +.BR * , +the case modification operation is applied to each member of the +array in turn, and the expansion is the resultant list. +.SS Command Substitution +.PP +\fICommand substitution\fP allows the output of a command to replace +the command name. There are two forms: +.RS +.PP +\fB$(\fP\fIcommand\fP\|\fB)\fP +.RE +or +.RS +\fB\`\fP\fIcommand\fP\fB\`\fP +.RE +.PP +.B Bash +performs the expansion by executing \fIcommand\fP 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 \fB$(cat \fIfile\fP)\fR can be replaced by +the equivalent but faster \fB$(< \fIfile\fP)\fR. +.PP +When the old-style backquote form of substitution is used, +backslash retains its literal meaning except when followed by +.BR $ , +.BR \` , +or +.BR \e . +The first backquote not preceded by a backslash terminates the +command substitution. +When using the $(\^\fIcommand\fP\|) form, all characters between the +parentheses make up the command; none are treated specially. +.PP +Command substitutions may be nested. To nest when using the backquoted form, +escape the inner backquotes with backslashes. +.PP +If the substitution appears within double quotes, word splitting and +pathname expansion are not performed on the results. +.SS Arithmetic Expansion +.PP +Arithmetic expansion allows the evaluation of an arithmetic expression +and the substitution of the result. The format for arithmetic expansion is: +.RS +.PP +\fB$((\fP\fIexpression\fP\fB))\fP +.RE +.PP +The +.I 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, string +expansion, command substitution, and quote removal. +Arithmetic expansions may be nested. +.PP +The evaluation is performed according to the rules listed below under +.SM +.BR "ARITHMETIC EVALUATION" . +If +.I expression +is invalid, +.B bash +prints a message indicating failure and no substitution occurs. +.SS Process Substitution +.PP +\fIProcess substitution\fP is supported on systems that support named +pipes (\fIFIFOs\fP) or the \fB/dev/fd\fP method of naming open files. +It takes the form of +\fB<(\fP\fIlist\^\fP\fB)\fP +or +\fB>(\fP\fIlist\^\fP\fB)\fP. +The process \fIlist\fP is run with its input or output connected to a +\fIFIFO\fP or some file in \fB/dev/fd\fP. The name of this file is +passed as an argument to the current command as the result of the +expansion. If the \fB>(\fP\fIlist\^\fP\fB)\fP form is used, writing to +the file will provide input for \fIlist\fP. If the +\fB<(\fP\fIlist\^\fP\fB)\fP form is used, the file passed as an +argument should be read to obtain the output of \fIlist\fP. +.PP +When available, process substitution is performed +simultaneously with parameter and variable expansion, +command substitution, +and arithmetic expansion. +.SS Word Splitting +.PP +The shell scans the results of +parameter expansion, +command substitution, +and +arithmetic expansion +that did not occur within double quotes for +.IR "word splitting" . +.PP +The shell treats each character of +.SM +.B IFS +as a delimiter, and splits the results of the other +expansions into words on these characters. If +.SM +.B IFS +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 not at the beginning or end serves to delimit words. +If +.SM +.B IFS +has a value other than the default, then sequences of +the whitespace characters +.B space +and +.B tab +are ignored at the beginning and end of the +word, as long as the whitespace character is in the +value of +.SM +.BR IFS +(an +.SM +.B IFS +whitespace character). +Any character in +.SM +.B IFS +that is not +.SM +.B IFS +whitespace, along with any adjacent +.SM +.B IFS +whitespace characters, delimits a field. +A sequence of +.SM +.B IFS +whitespace characters is also treated as a delimiter. +If the value of +.SM +.B IFS +is null, no word splitting occurs. +.PP +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 +null argument results and is retained. +.PP +Note that if no expansion occurs, no splitting +is performed. +.SS Pathname Expansion +.PP +After word splitting, +unless the +.B \-f +option has been set, +.B bash +scans each word for the characters +.BR * , +.BR ? , +and +.BR [ . +If one of these characters appears, then the word is +regarded as a +.IR pattern , +and replaced with an alphabetically sorted list of +file names matching the pattern +(see +.SM +.B "Pattern Matching" +below). +If no matching file names are found, +and the shell option +.B nullglob +is not enabled, the word is left unchanged. +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 +of alphabetic characters. +When a pattern is used for pathname expansion, +the character +.B ``.'' +at the start of a name or immediately following a slash +must be matched explicitly, unless the shell option +.B dotglob +is set. +When matching a pathname, the slash character must always be +matched explicitly. +In other cases, the +.B ``.'' +character is not treated specially. +See the description of +.B shopt +below under +.SM +.B SHELL BUILTIN COMMANDS +for a description of the +.BR nocaseglob , +.BR nullglob , +.BR failglob , +and +.B dotglob +shell options. +.PP +The +.SM +.B GLOBIGNORE +shell variable may be used to restrict the set of file names matching a +.IR pattern . +If +.SM +.B GLOBIGNORE +is set, each matching file name that also matches one of the patterns in +.SM +.B GLOBIGNORE +is removed from the list of matches. +The file names +.B ``.'' +and +.B ``..'' +are always ignored when +.SM +.B GLOBIGNORE +is set and not null. However, setting +.SM +.B GLOBIGNORE +to a non-null value has the effect of enabling the +.B dotglob +shell option, so all other file names beginning with a +.B ``.'' +will match. +To get the old behavior of ignoring file names beginning with a +.BR ``.'' , +make +.B ``.*'' +one of the patterns in +.SM +.BR GLOBIGNORE . +The +.B dotglob +option is disabled when +.SM +.B GLOBIGNORE +is unset. +.PP +\fBPattern Matching\fP +.PP +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. +.PP +The special pattern characters have the following meanings: +.PP +.PD 0 +.RS +.TP +.B * +Matches any string, including the null string. +When the \fBglobstar\fP shell option is enabled, and \fB*\fP is used in +a pathname expansion context, two adjacent \fB*\fPs used as a single +pattern will match all files and zero or more directories and +subdirectories. +If followed by a \fB/\fP, two adjacent \fB*\fPs will match only directories +and subdirectories. +.TP +.B ? +Matches any single character. +.TP +.B [...] +Matches any one of the enclosed characters. A pair of characters +separated by a hyphen denotes a +\fIrange expression\fP; +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 +.B [ +is a +.B ! +or a +.B ^ +then any character not enclosed is matched. +The sorting order of characters in range expressions is determined by +the current locale and the values of the +.SM +.B LC_COLLATE +or +.SM +.B LC_ALL +shell variables, if set. +To obtain the traditional interpretation of range expressions, where +.B [a\-d] +is equivalent to +.BR [abcd] , +set value of the +.B LC_ALL +shell variable to +.BR C , +or enable the +.B globasciiranges +shell option. +A +.B \- +may be matched by including it as the first or last character +in the set. +A +.B ] +may be matched by including it as the first character +in the set. +.br +.if t .sp 0.5 +.if n .sp 1 +Within +.B [ +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 standard: +.PP +.RS +.B +.if n alnum alpha ascii blank cntrl digit graph lower print punct space upper word xdigit +.if t alnum alpha ascii blank cntrl digit graph lower print punct space upper word xdigit +.br +A character class matches any character belonging to that class. +The \fBword\fP character class matches letters, digits, and the character _. +.br +.if t .sp 0.5 +.if n .sp 1 +Within +.B [ +and +.BR ] , +an \fIequivalence class\fP can be specified using the syntax +\fB[=\fP\fIc\fP\fB=]\fP, which matches all characters with the +same collation weight (as defined by the current locale) as +the character \fIc\fP. +.br +.if t .sp 0.5 +.if n .sp 1 +Within +.B [ +and +.BR ] , +the syntax \fB[.\fP\fIsymbol\fP\fB.]\fP matches the collating symbol +\fIsymbol\fP. +.RE +.RE +.PD +.PP +If the \fBextglob\fP shell option is enabled using the \fBshopt\fP +builtin, several extended pattern matching operators are recognized. +In the following description, a \fIpattern-list\fP is a list of one +or more patterns separated by a \fB|\fP. +Composite patterns may be formed using one or more of the following +sub-patterns: +.sp 1 +.PD 0 +.RS +.TP +\fB?(\fP\^\fIpattern-list\^\fP\fB)\fP +Matches zero or one occurrence of the given patterns +.TP +\fB*(\fP\^\fIpattern-list\^\fP\fB)\fP +Matches zero or more occurrences of the given patterns +.TP +\fB+(\fP\^\fIpattern-list\^\fP\fB)\fP +Matches one or more occurrences of the given patterns +.TP +\fB@(\fP\^\fIpattern-list\^\fP\fB)\fP +Matches one of the given patterns +.TP +\fB!(\fP\^\fIpattern-list\^\fP\fB)\fP +Matches anything except one of the given patterns +.RE +.PD +.SS Quote Removal +.PP +After the preceding expansions, all unquoted occurrences of the +characters +.BR \e , +.BR \(aq , +and \^\f3"\fP\^ that did not result from one of the above +expansions are removed. +.SH REDIRECTION +Before a command is executed, its input and output +may be +.I 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 +.I simple command +or may follow a +.IR command . +Redirections are processed in the order they appear, from +left to right. +.PP +Each redirection that may be preceded by a file descriptor number +may instead be preceded by a word of the form {\fIvarname\fP}. +In this case, for each redirection operator except +>&- and <&-, the shell will allocate a file descriptor greater +than or equal to 10 and assign it to \fIvarname\fP. +If >&- or <&- is preceded +by {\fIvarname\fP}, the value of \fIvarname\fP defines the file +descriptor to close. +.PP +In the following descriptions, if the file descriptor number is +omitted, and the first character of the redirection operator is +.BR < , +the redirection refers to the standard input (file descriptor +0). If the first character of the redirection operator is +.BR > , +the redirection refers to the standard output (file descriptor +1). +.PP +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, pathname expansion, and word splitting. +If it expands to more than one word, +.B bash +reports an error. +.PP +Note that the order of redirections is significant. For example, +the command +.RS +.PP +ls \fB>\fP dirlist 2\fB>&\fP1 +.RE +.PP +directs both standard output and standard error to the file +.IR dirlist , +while the command +.RS +.PP +ls 2\fB>&\fP1 \fB>\fP dirlist +.RE +.PP +directs only the standard output to file +.IR dirlist , +because the standard error was duplicated from the standard output +before the standard output was redirected to +.IR dirlist . +.PP +\fBBash\fP handles several filenames specially when they are used in +redirections, as described in the following table: +.RS +.PP +.PD 0 +.TP +.B /dev/fd/\fIfd\fP +If \fIfd\fP is a valid integer, file descriptor \fIfd\fP is duplicated. +.TP +.B /dev/stdin +File descriptor 0 is duplicated. +.TP +.B /dev/stdout +File descriptor 1 is duplicated. +.TP +.B /dev/stderr +File descriptor 2 is duplicated. +.TP +.B /dev/tcp/\fIhost\fP/\fIport\fP +If \fIhost\fP is a valid hostname or Internet address, and \fIport\fP +is an integer port number or service name, \fBbash\fP attempts to open +a TCP connection to the corresponding socket. +.TP +.B /dev/udp/\fIhost\fP/\fIport\fP +If \fIhost\fP is a valid hostname or Internet address, and \fIport\fP +is an integer port number or service name, \fBbash\fP attempts to open +a UDP connection to the corresponding socket. +.PD +.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 +the expansion of +.I word +to be opened for reading on file descriptor +.IR n , +or the standard input (file descriptor 0) if +.I n +is not specified. +.PP +The general format for redirecting input is: +.RS +.PP +[\fIn\fP]\fB<\fP\fIword\fP +.RE +.SS Redirecting Output +.PP +Redirection of output causes the file whose name results from +the expansion of +.I word +to be opened for writing on file descriptor +.IR n , +or the standard output (file descriptor 1) if +.I n +is not specified. If the file does not exist it is created; +if it does exist it is truncated to zero size. +.PP +The general format for redirecting output is: +.RS +.PP +[\fIn\fP]\fB>\fP\fIword\fP +.RE +.PP +If the redirection operator is +.BR > , +and the +.B noclobber +option to the +.B set +builtin has been enabled, the redirection will fail if the file +whose name results from the expansion of \fIword\fP exists and is +a regular file. +If the redirection operator is +.BR >| , +or the redirection operator is +.B > +and the +.B noclobber +option to the +.B set +builtin command is not enabled, the redirection is attempted even +if the file named by \fIword\fP exists. +.SS Appending Redirected Output +.PP +Redirection of output in this fashion +causes the file whose name results from +the expansion of +.I word +to be opened for appending on file descriptor +.IR n , +or the standard output (file descriptor 1) if +.I n +is not specified. If the file does not exist it is created. +.PP +The general format for appending output is: +.RS +.PP +[\fIn\fP]\fB>>\fP\fIword\fP +.RE +.PP +.SS Redirecting Standard Output and Standard Error +.PP +This construct 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 +.IR word . +.PP +There are two formats for redirecting standard output and +standard error: +.RS +.PP +\fB&>\fP\fIword\fP +.RE +and +.RS +\fB>&\fP\fIword\fP +.RE +.PP +Of the two forms, the first is preferred. +This is semantically equivalent to +.RS +.PP +\fB>\fP\fIword\fP 2\fB>&\fP1 +.RE +.PP +(see \fBDuplicating File Descriptors\fP below). +.SS Appending Standard Output and Standard Error +.PP +This construct allows both the +standard output (file descriptor 1) and +the standard error output (file descriptor 2) +to be appended to the file whose name is the +expansion of +.IR word . +.PP +The format for appending standard output and standard error is: +.RS +.PP +\fB&>>\fP\fIword\fP +.RE +.PP +This is semantically equivalent to +.RS +.PP +\fB>>\fP\fIword\fP 2\fB>&\fP1 +.RE +.PP +(see \fBDuplicating File Descriptors\fP below). +.SS Here Documents +.PP +This type of redirection instructs the shell to read input from the +current source until a line containing only +.I delimiter +(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. +.PP +The format of here-documents is: +.RS +.PP +.nf +\fB<<\fP[\fB\-\fP]\fIword\fP + \fIhere-document\fP +\fIdelimiter\fP +.fi +.RE +.PP +No parameter expansion, command substitution, arithmetic expansion, +or pathname expansion is performed on +.IR word . +If any characters in +.I word +are quoted, the +.I delimiter +is the result of quote removal on +.IR word , +and the lines in the here-document are not expanded. +If \fIword\fP 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 +.B \e +is ignored, and +.B \e +must be used to quote the characters +.BR \e , +.BR $ , +and +.BR \` . +.PP +If the redirection operator is +.BR <<\- , +then all leading tab characters are stripped from input lines and the +line containing +.IR delimiter . +This allows +here-documents within shell scripts to be indented in a +natural fashion. +.SS "Here Strings" +A variant of here documents, the format is: +.RS +.PP +.nf +\fB<<<\fP\fIword\fP +.fi +.RE +.PP +The \fIword\fP +is expanded as described above, with the exception that +pathname expansion is not applied, and supplied as a single string +to the command on its standard input. +.SS "Duplicating File Descriptors" +.PP +The redirection operator +.RS +.PP +[\fIn\fP]\fB<&\fP\fIword\fP +.RE +.PP +is used to duplicate input file descriptors. +If +.I word +expands to one or more digits, the file descriptor denoted by +.I n +is made to be a copy of that file descriptor. +If the digits in +.I word +do not specify a file descriptor open for input, a redirection error occurs. +If +.I word +evaluates to +.BR \- , +file descriptor +.I n +is closed. If +.I n +is not specified, the standard input (file descriptor 0) is used. +.PP +The operator +.RS +.PP +[\fIn\fP]\fB>&\fP\fIword\fP +.RE +.PP +is used similarly to duplicate output file descriptors. If +.I n +is not specified, the standard output (file descriptor 1) is used. +If the digits in +.I word +do not specify a file descriptor open for output, a redirection error occurs. +As a special case, if \fIn\fP is omitted, and \fIword\fP does not +expand to one or more digits, the standard output and standard +error are redirected as described previously. +.SS "Moving File Descriptors" +.PP +The redirection operator +.RS +.PP +[\fIn\fP]\fB<&\fP\fIdigit\fP\fB\-\fP +.RE +.PP +moves the file descriptor \fIdigit\fP to file descriptor +.IR n , +or the standard input (file descriptor 0) if \fIn\fP is not specified. +\fIdigit\fP is closed after being duplicated to \fIn\fP. +.PP +Similarly, the redirection operator +.RS +.PP +[\fIn\fP]\fB>&\fP\fIdigit\fP\fB\-\fP +.RE +.PP +moves the file descriptor \fIdigit\fP to file descriptor +.IR n , +or the standard output (file descriptor 1) if \fIn\fP is not specified. +.SS "Opening File Descriptors for Reading and Writing" +.PP +The redirection operator +.RS +.PP +[\fIn\fP]\fB<>\fP\fIword\fP +.RE +.PP +causes the file whose name is the expansion of +.I word +to be opened for both reading and writing on file descriptor +.IR n , +or on file descriptor 0 if +.I n +is not specified. If the file does not exist, it is created. +.SH ALIASES +\fIAliases\fP 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 +.B alias +and +.B unalias +builtin commands (see +.SM +.B SHELL BUILTIN COMMANDS +below). +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 \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 +.B ls +to +.BR "ls \-F" , +for instance, and +.B bash +does not try to recursively expand the replacement text. +If the last character of the alias value is a +.IR blank , +then the next command +word following the alias is also checked for alias expansion. +.PP +Aliases are created and listed with the +.B alias +command, and removed with the +.B unalias +command. +.PP +There is no mechanism for using arguments in the replacement text. +If arguments are needed, a shell function should be used (see +.SM +.B FUNCTIONS +below). +.PP +Aliases are not expanded when the shell is not interactive, unless +the +.B expand_aliases +shell option is set using +.B shopt +(see the description of +.B shopt +under +.SM +\fBSHELL BUILTIN COMMANDS\fP +below). +.PP +The rules concerning the definition and use of aliases are +somewhat confusing. +.B 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 +.B alias +in compound commands. +.PP +For almost every purpose, aliases are superseded by +shell functions. +.SH FUNCTIONS +A shell function, defined as described above under +.SM +.BR "SHELL GRAMMAR" , +stores a series of commands for later execution. +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. +Functions are executed in the context of the +current shell; no new process is created to interpret +them (contrast this with the execution of a shell script). +When a function is executed, the arguments to the +function become the positional parameters +during its execution. +The special parameter +.B # +is updated to reflect the change. Special parameter \fB0\fP +is unchanged. +The first element of the +.SM +.B FUNCNAME +variable is set to the name of the function while the function +is executing. +.PP +All other aspects of the shell execution +environment are identical between a function and its caller +with these exceptions: the +.SM +.B DEBUG +and +.B RETURN +traps (see the description of the +.B trap +builtin under +.SM +.B SHELL BUILTIN COMMANDS +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 and \fBRETURN\fP traps), +and the +.SM +.B ERR +trap is not inherited unless the \fB\-o errtrace\fP shell option has +been enabled. +.PP +Variables local to the function may be declared with the +.B local +builtin command. Ordinarily, variables and their values +are shared between the function and its caller. +.PP +The \fBFUNCNEST\fP variable, if set to a numeric value greater +than 0, defines a maximum function nesting level. Function +invocations that exceed the limit cause the entire command to +abort. +.PP +If the builtin command +.B 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 \fBRETURN\fP trap is executed +before execution resumes. +When a function completes, the values of the +positional parameters and the special parameter +.B # +are restored to the values they had prior to the function's +execution. +.PP +Function names and definitions may be listed with the +.B \-f +option to the +.B declare +or +.B typeset +builtin commands. The +.B \-F +option to +.B declare +or +.B typeset +will list the function names only +(and optionally the source file and line number, if the \fBextdebug\fP +shell option is enabled). +Functions may be exported so that subshells +automatically have them defined with the +.B \-f +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. +Care should be taken in cases where this may cause a problem. +.PP +Functions may be recursive. +The \fBFUNCNEST\fP variable may be used to limit the depth of the +function call stack and restrict the number of function invocations. +By default, no limit is imposed on the number of recursive calls. +.SH "ARITHMETIC EVALUATION" +The shell allows arithmetic expressions to be evaluated, under +certain circumstances (see the \fBlet\fP and \fBdeclare\fP builtin +commands and \fBArithmetic Expansion\fP). +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. +.PP +.PD 0 +.TP +.B \fIid\fP++ \fIid\fP\-\- +variable post-increment and post-decrement +.TP +.B ++\fIid\fP \-\-\fIid\fP +variable pre-increment and pre-decrement +.TP +.B \- + +unary minus and plus +.TP +.B ! ~ +logical and bitwise negation +.TP +.B ** +exponentiation +.TP +.B * / % +multiplication, division, remainder +.TP +.B + \- +addition, subtraction +.TP +.B << >> +left and right bitwise shifts +.TP +.B <= >= < > +comparison +.TP +.B == != +equality and inequality +.TP +.B & +bitwise AND +.TP +.B ^ +bitwise exclusive OR +.TP +.B | +bitwise OR +.TP +.B && +logical AND +.TP +.B || +logical OR +.TP +.B \fIexpr\fP?\fIexpr\fP:\fIexpr\fP +conditional operator +.TP +.B = *= /= %= += \-= <<= >>= &= ^= |= +assignment +.TP +.B \fIexpr1\fP , \fIexpr2\fP +comma +.PD +.PP +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 +\fIinteger\fP attribute using \fBdeclare -i\fP is assigned a value. +A null value evaluates to 0. +A shell variable need not have its \fIinteger\fP attribute +turned on to be used in an expression. +.PP +Constants with a leading 0 are interpreted as octal numbers. +A leading 0x or 0X denotes hexadecimal. +Otherwise, numbers take the form [\fIbase#\fP]n, where the optional \fIbase\fP +is a decimal number between 2 and 64 representing the arithmetic +base, and \fIn\fP is a number in that base. +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 interchangeably to represent numbers between 10 +and 35. +.PP +Operators are evaluated in order of precedence. Sub-expressions in +parentheses are evaluated first and may override the precedence +rules above. +.SH "CONDITIONAL EXPRESSIONS" +Conditional expressions are used by the \fB[[\fP compound command and +the \fBtest\fP and \fB[\fP builtin commands to test file attributes +and perform string and arithmetic comparisons. +Expressions are formed from the following unary or binary primaries. +If any \fIfile\fP argument to one of the primaries is of the form +\fI/dev/fd/n\fP, then file descriptor \fIn\fP is checked. +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. +.if t .sp 0.5 +.if n .sp 1 +When used with \fB[[\fP, the \fB<\fP and \fB>\fP operators sort +lexicographically using the current locale. +The \fBtest\fP command sorts using ASCII ordering. +.sp 1 +.PD 0 +.TP +.B \-a \fIfile\fP +True if \fIfile\fP exists. +.TP +.B \-b \fIfile\fP +True if \fIfile\fP exists and is a block special file. +.TP +.B \-c \fIfile\fP +True if \fIfile\fP exists and is a character special file. +.TP +.B \-d \fIfile\fP +True if \fIfile\fP exists and is a directory. +.TP +.B \-e \fIfile\fP +True if \fIfile\fP exists. +.TP +.B \-f \fIfile\fP +True if \fIfile\fP exists and is a regular file. +.TP +.B \-g \fIfile\fP +True if \fIfile\fP exists and is set-group-id. +.TP +.B \-h \fIfile\fP +True if \fIfile\fP exists and is a symbolic link. +.TP +.B \-k \fIfile\fP +True if \fIfile\fP exists and its ``sticky'' bit is set. +.TP +.B \-p \fIfile\fP +True if \fIfile\fP exists and is a named pipe (FIFO). +.TP +.B \-r \fIfile\fP +True if \fIfile\fP exists and is readable. +.TP +.B \-s \fIfile\fP +True if \fIfile\fP exists and has a size greater than zero. +.TP +.B \-t \fIfd\fP +True if file descriptor +.I fd +is open and refers to a terminal. +.TP +.B \-u \fIfile\fP +True if \fIfile\fP exists and its set-user-id bit is set. +.TP +.B \-w \fIfile\fP +True if \fIfile\fP exists and is writable. +.TP +.B \-x \fIfile\fP +True if \fIfile\fP exists and is executable. +.TP +.B \-G \fIfile\fP +True if \fIfile\fP exists and is owned by the effective group id. +.TP +.B \-L \fIfile\fP +True if \fIfile\fP exists and is a symbolic link. +.TP +.B \-N \fIfile\fP +True if \fIfile\fP exists and has been modified since it was last read. +.TP +.B \-O \fIfile\fP +True if \fIfile\fP exists and is owned by the effective user id. +.TP +.B \-S \fIfile\fP +True if \fIfile\fP exists and is a socket. +.TP +\fIfile1\fP \fB\-ef\fP \fIfile2\fP +True if \fIfile1\fP and \fIfile2\fP refer to the same device and +inode numbers. +.TP +\fIfile1\fP \-\fBnt\fP \fIfile2\fP +True if \fIfile1\fP is newer (according to modification date) than \fIfile2\fP, +or if \fIfile1\fP exists and \fPfile2\fP does not. +.TP +\fIfile1\fP \-\fBot\fP \fIfile2\fP +True if \fIfile1\fP is older than \fIfile2\fP, or if \fIfile2\fP exists +and \fIfile1\fP does not. +.TP +.B \-o \fIoptname\fP +True if the shell option +.I optname +is enabled. +See the list of options under the description of the +.B \-o +option to the +.B set +builtin below. +.TP +.B \-v \fIvarname\fP +True if the shell variable +.I varname +is set (has been assigned a value). +.TP +.B \-z \fIstring\fP +True if the length of \fIstring\fP is zero. +.TP +\fIstring\fP +.PD 0 +.TP +.B \-n \fIstring\fP +.PD +True if the length of +.I string +is non-zero. +.TP +\fIstring1\fP \fB==\fP \fIstring2\fP +.PD 0 +.TP +\fIstring1\fP \fB=\fP \fIstring2\fP +.PD +True if the strings are equal. \fB=\fP should be used +with the \fBtest\fP command for POSIX conformance. +.TP +\fIstring1\fP \fB!=\fP \fIstring2\fP +True if the strings are not equal. +.TP +\fIstring1\fP \fB<\fP \fIstring2\fP +True if \fIstring1\fP sorts before \fIstring2\fP lexicographically. +.TP +\fIstring1\fP \fB>\fP \fIstring2\fP +True if \fIstring1\fP sorts after \fIstring2\fP lexicographically. +.TP +.I \fIarg1\fP \fBOP\fP \fIarg2\fP +.SM +.B OP +is one of +.BR \-eq , +.BR \-ne , +.BR \-lt , +.BR \-le , +.BR \-gt , +or +.BR \-ge . +These arithmetic binary operators return true if \fIarg1\fP +is equal to, not equal to, less than, less than or equal to, +greater than, or greater than or equal to \fIarg2\fP, respectively. +.I Arg1 +and +.I arg2 +may be positive or negative integers. +.PD +.SH "SIMPLE COMMAND EXPANSION" +When a simple command is executed, the shell performs the following +expansions, assignments, and redirections, from left to right. +.IP 1. +The words that the parser has marked as variable assignments (those +preceding the command name) and redirections are saved for later +processing. +.IP 2. +The words that are not variable assignments or redirections are +expanded. 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. +.IP 3. +Redirections are performed as described above under +.SM +.BR REDIRECTION . +.IP 4. +The text after the \fB=\fP in each variable assignment undergoes tilde +expansion, parameter expansion, command substitution, arithmetic expansion, +and quote removal before being assigned to the variable. +.PP +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. +.PP +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. +.PP +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. +.SH "COMMAND 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. +.PP +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 above in +.SM +.BR FUNCTIONS . +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. +.PP +If the name is neither a shell function nor a builtin, +and contains no slashes, +.B bash +searches each element of the +.SM +.B PATH +for a directory containing an executable file by that name. +.B Bash +uses a hash table to remember the full pathnames of executable +files (see +.B hash +under +.SM +.B "SHELL BUILTIN COMMANDS" +below). +A full search of the directories in +.SM +.B PATH +is performed only if the command is not found in the hash table. +If the search is unsuccessful, the shell searches for a defined shell +function named \fBcommand_not_found_handle\fP. +If that function exists, it is invoked with the original command and +the original command's arguments as its arguments, and the function's +exit status becomes the exit status of the shell. +If that function is not defined, the shell prints an error +message and returns an exit status of 127. +.PP +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 given, if any. +.PP +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 \fIshell script\fP, a file +containing shell commands. A subshell is spawned to execute +it. This subshell reinitializes itself, so +that the effect is as if a new shell had been invoked +to handle the script, with the exception that the locations of +commands remembered by the parent (see +.B hash +below under +.SM +\fBSHELL BUILTIN COMMANDS\fP) +are retained by the child. +.PP +If the program is a file beginning with +.BR #! , +the remainder of the first line specifies an interpreter +for the program. The shell executes the +specified interpreter on operating systems that do not +handle this executable format themselves. The arguments to the +interpreter consist of a single optional argument following the +interpreter name on the first line of the program, followed +by the name of the program, followed by the command +arguments, if any. +.SH COMMAND EXECUTION ENVIRONMENT +The shell has an \fIexecution environment\fP, which consists of the +following: +.IP \(bu +open files inherited by the shell at invocation, as modified by +redirections supplied to the \fBexec\fP builtin +.IP \(bu +the current working directory as set by \fBcd\fP, \fBpushd\fP, or +\fBpopd\fP, or inherited by the shell at invocation +.IP \(bu +the file creation mode mask as set by \fBumask\fP or inherited from +the shell's parent +.IP \(bu +current traps set by \fBtrap\fP +.IP \(bu +shell parameters that are set by variable assignment or with \fBset\fP +or inherited from the shell's parent in the environment +.IP \(bu +shell functions defined during execution or inherited from the shell's +parent in the environment +.IP \(bu +options enabled at invocation (either by default or with command-line +arguments) or by \fBset\fP +.IP \(bu +options enabled by \fBshopt\fP +.IP \(bu +shell aliases defined with \fBalias\fP +.IP \(bu +various process IDs, including those of background jobs, the value +of \fB$$\fP, and the value of +.SM +.B PPID +.PP +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. +.if n .sp 1 +.IP \(bu +the shell's open files, plus any modifications and additions specified +by redirections to the command +.IP \(bu +the current working directory +.IP \(bu +the file creation mode mask +.IP \(bu +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 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, 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. +.PP +Subshells spawned to execute command substitutions inherit the value of +the \fB\-e\fP option from the parent shell. When not in \fIposix\fP mode, +\fBbash\fP clears the \fB\-e\fP option in such subshells. +.PP +If a command is followed by a \fB&\fP and job control is not active, the +default standard input for the command is the empty file \fI/dev/null\fP. +Otherwise, the invoked command inherits the file descriptors of the calling +shell as modified by redirections. +.SH ENVIRONMENT +When a program is invoked it is given an array of strings +called the +.IR environment . +This is a list of +\fIname\fP\-\fIvalue\fP pairs, of the form +.IR "name\fR=\fPvalue" . +.PP +The shell 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 +.I export +to child processes. Executed commands inherit the environment. +The +.B export +and +.B 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 +.B unset +command, plus any additions via the +.B export +and +.B declare \-x +commands. +.PP +The environment for any +.I simple command +or function may be augmented temporarily by prefixing it with +parameter assignments, as described above in +.SM +.BR PARAMETERS . +These assignment statements affect only the environment seen +by that command. +.PP +If the +.B \-k +option is set (see the +.B set +builtin command below), then +.I all +parameter assignments are placed in the environment for a command, +not just those that precede the command name. +.PP +When +.B bash +invokes an external command, the variable +.B _ +is set to the full file name of the command and passed to that +command in its environment. +.SH "EXIT STATUS" +.PP +The exit status of an executed command is the value returned by the +\fIwaitpid\fP system call or equivalent function. Exit statuses +fall between 0 and 255, though, as explained below, the shell may +use values above 125 specially. Exit statuses from shell builtins and +compound commands are also limited to this range. Under certain +circumstances, the shell will use special values to indicate specific +failure modes. +.PP +For the shell's purposes, a command which exits with a +zero exit status has succeeded. An exit status of zero +indicates success. A non-zero exit status indicates failure. +When a command terminates on a fatal signal \fIN\fP, \fBbash\fP uses +the value of 128+\fIN\fP as the exit status. +.PP +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. +.PP +If a command fails because of an error during expansion or redirection, +the exit status is greater than zero. +.PP +Shell builtin commands return a status of 0 (\fItrue\fP) if +successful, and non-zero (\fIfalse\fP) if an error occurs +while they execute. +All builtins return an exit status of 2 to indicate incorrect usage. +.PP +\fBBash\fP itself returns the exit status of the last command +executed, unless a syntax error occurs, in which case it exits +with a non-zero value. See also the \fBexit\fP builtin +command below. +.SH SIGNALS +When \fBbash\fP is interactive, in the absence of any traps, it ignores +.SM +.B SIGTERM +(so that \fBkill 0\fP does not kill an interactive shell), +and +.SM +.B SIGINT +is caught and handled (so that the \fBwait\fP builtin is interruptible). +In all cases, \fBbash\fP ignores +.SM +.BR SIGQUIT . +If job control is in effect, +.B bash +ignores +.SM +.BR SIGTTIN , +.SM +.BR SIGTTOU , +and +.SM +.BR SIGTSTP . +.PP +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 +.SM +.B SIGINT +and +.SM +.B SIGQUIT +in addition to these inherited handlers. +Commands run as a result of command substitution ignore the +keyboard-generated job control signals +.SM +.BR SIGTTIN , +.SM +.BR SIGTTOU , +and +.SM +.BR SIGTSTP . +.PP +The shell exits by default upon receipt of a +.SM +.BR SIGHUP . +Before exiting, an interactive shell resends the +.SM +.B SIGHUP +to all jobs, running or stopped. +Stopped jobs are sent +.SM +.B SIGCONT +to ensure that they receive the +.SM +.BR SIGHUP . +To prevent the shell from +sending the signal to a particular job, it should be removed from the +jobs table with the +.B disown +builtin (see +.SM +.B "SHELL BUILTIN COMMANDS" +below) or marked +to not receive +.SM +.B SIGHUP +using +.BR "disown \-h" . +.PP +If the +.B huponexit +shell option has been set with +.BR shopt , +.B bash +sends a +.SM +.B SIGHUP +to all jobs when an interactive login shell exits. +.PP +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 +greater than 128, immediately after which the trap is executed. +.SH "JOB CONTROL" +.I Job control +refers to the ability to selectively stop (\fIsuspend\fP) +the execution of processes and continue (\fIresume\fP) +their execution at a later point. A user typically employs +this facility via an interactive interface supplied jointly +by the operating system kernel's terminal driver and +.BR bash . +.PP +The shell associates a +.I job +with each pipeline. It keeps a table of currently executing +jobs, which may be listed with the +.B jobs +command. When +.B bash +starts a job asynchronously (in the +.IR background ), +it prints a line that looks like: +.RS +.PP +[1] 25647 +.RE +.PP +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. +.B Bash +uses the +.I job +abstraction as the basis for job control. +.PP +To facilitate the implementation of the user interface to job +control, the operating system maintains the notion of a \fIcurrent terminal +process group ID\fP. 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 +.SM +.BR SIGINT . +These processes are said to be in the +.IR foreground . +.I 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, if the +user so specifies with \f(CWstty tostop\fP, write to the +terminal. +Background processes which attempt to read from (write to when +\f(CWstty tostop\fP is in effect) the +terminal are sent a +.SM +.B SIGTTIN (SIGTTOU) +signal by the kernel's terminal driver, +which, unless caught, suspends the process. +.PP +If the operating system on which +.B bash +is running supports +job control, +.B bash +contains facilities to use it. +Typing the +.I suspend +character (typically +.BR ^Z , +Control-Z) while a process is running +causes that process to be stopped and returns control to +.BR bash . +Typing the +.I "delayed suspend" +character (typically +.BR ^Y , +Control-Y) causes the process to be stopped when it +attempts to read input from the terminal, and control to +be returned to +.BR bash . +The user may then manipulate the state of this job, using the +.B bg +command to continue it in the background, the +.B fg +command to continue it in the foreground, or +the +.B kill +command to kill it. A \fB^Z\fP takes effect immediately, +and has the additional side effect of causing pending output +and typeahead to be discarded. +.PP +There are a number of ways to refer to a job in the shell. +The character +.B % +introduces a job specification (\fIjobspec\fP). Job number +.I n +may be referred to as +.BR %n . +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, +.B %ce +refers to a stopped +.B ce +job. If a prefix matches more than one job, +.B bash +reports an error. Using +.BR %?ce , +on the other hand, refers to any job containing the string +.B ce +in its command line. If the substring matches more than one job, +.B bash +reports an error. The symbols +.B %% +and +.B %+ +refer to the shell's notion of the +.IR "current job" , +which is the last job stopped while it was in +the foreground or started in the background. +The +.I "previous job" +may be referenced using +.BR %\- . +If there is only a single job, \fB%+\fP and \fB%\-\fP can both be used +to refer to that job. +In output pertaining to jobs (e.g., the output of the +.B jobs +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: +.B %1 +is a synonym for +\fB``fg %1''\fP, +bringing job 1 from the background into the foreground. +Similarly, +.B ``%1 &'' +resumes job 1 in the background, equivalent to +\fB``bg %1''\fP. +.PP +The shell learns immediately whenever a job changes state. +Normally, +.B 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 \-b +option to the +.B set +builtin command +is enabled, +.B bash +reports such changes immediately. +Any trap on +.SM +.B SIGCHLD +is executed for each child that exits. +.PP +If an attempt to exit +.B bash +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. +If a second attempt to exit is made without an intervening command, +the shell does not print another warning, and any stopped +jobs are terminated. +.SH PROMPTING +When executing interactively, +.B bash +displays the primary prompt +.SM +.B PS1 +when it is ready to read a command, and the secondary prompt +.SM +.B PS2 +when it needs more input to complete a command. +.B Bash +allows these prompt strings to be customized by inserting a number of +backslash-escaped special characters that are decoded as follows: +.RS +.PD 0 +.TP +.B \ea +an ASCII bell character (07) +.TP +.B \ed +the date in "Weekday Month Date" format (e.g., "Tue May 26") +.TP +.B \eD{\fIformat\fP} +the \fIformat\fP is passed to \fIstrftime\fP(3) and the result is inserted +into the prompt string; an empty \fIformat\fP results in a locale-specific +time representation. The braces are required +.TP +.B \ee +an ASCII escape character (033) +.TP +.B \eh +the hostname up to the first `.' +.TP +.B \eH +the hostname +.TP +.B \ej +the number of jobs currently managed by the shell +.TP +.B \el +the basename of the shell's terminal device name +.TP +.B \en +newline +.TP +.B \er +carriage return +.TP +.B \es +the name of the shell, the basename of +.B $0 +(the portion following the final slash) +.TP +.B \et +the current time in 24-hour HH:MM:SS format +.TP +.B \eT +the current time in 12-hour HH:MM:SS format +.TP +.B \e@ +the current time in 12-hour am/pm format +.TP +.B \eA +the current time in 24-hour HH:MM format +.TP +.B \eu +the username of the current user +.TP +.B \ev +the version of \fBbash\fP (e.g., 2.00) +.TP +.B \eV +the release of \fBbash\fP, version + patch level (e.g., 2.00.0) +.TP +.B \ew +the current working directory, with +.SM +.B $HOME +abbreviated with a tilde +(uses the value of the +.SM +.B PROMPT_DIRTRIM +variable) +.TP +.B \eW +the basename of the current working directory, with +.SM +.B $HOME +abbreviated with a tilde +.TP +.B \e! +the history number of this command +.TP +.B \e# +the command number of this command +.TP +.B \e$ +if the effective UID is 0, a +.BR # , +otherwise a +.B $ +.TP +.B \e\fInnn\fP +the character corresponding to the octal number \fInnn\fP +.TP +.B \e\e +a backslash +.TP +.B \e[ +begin a sequence of non-printing characters, which could be used to +embed a terminal control sequence into the prompt +.TP +.B \e] +end a sequence of non-printing characters +.PD +.RE +.PP +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 +.SM +.B HISTORY +below), 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 +.B promptvars +shell option (see the description of the +.B shopt +command under +.SM +.B "SHELL BUILTIN COMMANDS" +below). +.SH READLINE +This is the library that handles reading input when using an interactive +shell, unless the +.B \-\-noediting +option is given at shell invocation. +Line editing is also used when using the \fB\-e\fP option to the +\fBread\fP builtin. +By default, the line editing commands are similar to those of Emacs. +A vi-style line editing interface is also available. +Line editing can be enabled at any time using the +.B \-o emacs +or +.B \-o vi +options to the +.B set +builtin (see +.SM +.B SHELL BUILTIN COMMANDS +below). +To turn off line editing after the shell is running, use the +.B +o emacs +or +.B +o vi +options to the +.B set +builtin. +.SS "Readline Notation" +.PP +In this section, the Emacs-style notation is used to denote +keystrokes. Control keys are denoted by C\-\fIkey\fR, e.g., C\-n +means Control\-N. Similarly, +.I meta +keys are denoted by M\-\fIkey\fR, so M\-x means Meta\-X. (On keyboards +without a +.I meta +key, M\-\fIx\fP means ESC \fIx\fP, i.e., press the Escape key +then the +.I x +key. This makes ESC the \fImeta prefix\fP. +The combination M\-C\-\fIx\fP means ESC\-Control\-\fIx\fP, +or press the Escape key +then hold the Control key while pressing the +.I x +key.) +.PP +Readline commands may be given numeric +.IR arguments , +which normally act as a repeat count. +Sometimes, however, it is the sign of the argument that is significant. +Passing a negative argument to a command that acts in the forward +direction (e.g., \fBkill\-line\fP) causes that command to act in a +backward direction. +Commands whose behavior with arguments deviates from this are noted +below. +.PP +When a command is described as \fIkilling\fP text, the text +deleted is saved for possible future retrieval +(\fIyanking\fP). The killed text is saved in a +\fIkill ring\fP. Consecutive kills cause the text to be +accumulated into one unit, which can be yanked all at once. +Commands which do not kill text separate the chunks of text +on the kill ring. +.SS "Readline Initialization" +.PP +Readline is customized by putting commands in an initialization +file (the \fIinputrc\fP file). +The name of this file is taken from the value of the +.SM +.B INPUTRC +variable. If that variable is unset, the default is +.IR ~/.inputrc . +When a program which uses the readline library starts up, the +initialization file is read, and the key bindings and variables +are set. +There are only a few basic constructs allowed in the +readline initialization file. +Blank lines are ignored. +Lines beginning with a \fB#\fP are comments. +Lines beginning with a \fB$\fP indicate conditional constructs. +Other lines denote key bindings and variable settings. +.PP +The default key-bindings may be changed with an +.I inputrc +file. +Other programs that use this library may add their own commands +and bindings. +.PP +For example, placing +.RS +.PP +M\-Control\-u: universal\-argument +.RE +or +.RS +C\-Meta\-u: universal\-argument +.RE +into the +.I inputrc +would make M\-C\-u execute the readline command +.IR universal\-argument . +.PP +The following symbolic character names are recognized: +.IR RUBOUT , +.IR DEL , +.IR ESC , +.IR LFD , +.IR NEWLINE , +.IR RET , +.IR RETURN , +.IR SPC , +.IR SPACE , +and +.IR TAB . +.PP +In addition to command names, readline allows keys to be bound +to a string that is inserted when the key is pressed (a \fImacro\fP). +.SS "Readline Key Bindings" +.PP +The syntax for controlling key bindings in the +.I inputrc +file is simple. All that is required is the name of the +command or the text of a macro and a key sequence to which +it should be bound. The name may be specified in one of two ways: +as a symbolic key name, possibly with \fIMeta\-\fP or \fIControl\-\fP +prefixes, or as a key sequence. +.PP +When using the form \fBkeyname\fP:\^\fIfunction\-name\fP or \fImacro\fP, +.I keyname +is the name of a key spelled out in English. For example: +.sp +.RS +Control-u: universal\-argument +.br +Meta-Rubout: backward-kill-word +.br +Control-o: "> output" +.RE +.LP +In the above example, +.I C\-u +is bound to the function +.BR universal\-argument , +.I M\-DEL +is bound to the function +.BR backward\-kill\-word , +and +.I C\-o +is bound to run the macro +expressed on the right hand side (that is, to insert the text +.if t \f(CW> output\fP +.if n ``> output'' +into the line). +.PP +In the second form, \fB"keyseq"\fP:\^\fIfunction\-name\fP or \fImacro\fP, +.B keyseq +differs from +.B keyname +above in that strings denoting +an entire key sequence may be specified by placing the sequence +within double quotes. Some GNU Emacs style key escapes can be +used, as in the following example, but the symbolic character names +are not recognized. +.sp +.RS +"\eC\-u": universal\-argument +.br +"\eC\-x\eC\-r": re\-read\-init\-file +.br +"\ee[11~": "Function Key 1" +.RE +.PP +In this example, +.I C\-u +is again bound to the function +.BR universal\-argument . +.I "C\-x C\-r" +is bound to the function +.BR re\-read\-init\-file , +and +.I "ESC [ 1 1 ~" +is bound to insert the text +.if t \f(CWFunction Key 1\fP. +.if n ``Function Key 1''. +.PP +The full set of GNU Emacs style escape sequences is +.RS +.PD 0 +.TP +.B \eC\- +control prefix +.TP +.B \eM\- +meta prefix +.TP +.B \ee +an escape character +.TP +.B \e\e +backslash +.TP +.B \e" +literal " +.TP +.B \e\(aq +literal \(aq +.RE +.PD +.PP +In addition to the GNU Emacs style escape sequences, a second +set of backslash escapes is available: +.RS +.PD 0 +.TP +.B \ea +alert (bell) +.TP +.B \eb +backspace +.TP +.B \ed +delete +.TP +.B \ef +form feed +.TP +.B \en +newline +.TP +.B \er +carriage return +.TP +.B \et +horizontal tab +.TP +.B \ev +vertical tab +.TP +.B \e\fInnn\fP +the eight-bit character whose value is the octal value \fInnn\fP +(one to three digits) +.TP +.B \ex\fIHH\fP +the eight-bit character whose value is the hexadecimal value \fIHH\fP +(one or two hex digits) +.RE +.PD +.PP +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 \(aq. +.PP +.B Bash +allows the current readline key bindings to be displayed or modified +with the +.B bind +builtin command. The editing mode may be switched during interactive +use by using the +.B \-o +option to the +.B set +builtin command (see +.SM +.B SHELL BUILTIN COMMANDS +below). +.SS "Readline Variables" +.PP +Readline has variables that can be used to further customize its +behavior. A variable may be set in the +.I inputrc +file with a statement of the form +.RS +.PP +\fBset\fP \fIvariable\-name\fP \fIvalue\fP +.RE +.PP +Except where noted, readline variables can take the values +.B On +or +.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 +.TP +.B bell\-style (audible) +Controls what happens when readline wants to ring the terminal bell. +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 +command is executed. +This command is bound to +.B M\-# +in emacs mode and to +.B # +in vi command mode. +.TP +.B completion\-ignore\-case (Off) +If set to \fBOn\fP, readline performs filename matching and completion +in a case\-insensitive fashion. +.TP +.B completion\-prefix\-display\-length (0) +The length in characters of the common prefix of a list of possible +completions that is displayed without modification. When set to a +value greater than zero, common prefixes longer than this value are +replaced with an ellipsis when displaying possible completions. +.TP +.B completion\-query\-items (100) +This determines when the user is queried about viewing +the number of possible completions +generated by the \fBpossible\-completions\fP command. +It may be set to any integer value greater than or equal to +zero. If the number of possible completions is greater than +or equal to the value of this variable, the user is asked whether +or not he wishes to view them; otherwise they are simply listed +on the terminal. +.TP +.B convert\-meta (On) +If set to \fBOn\fP, readline will convert characters with the +eighth bit set to an ASCII key sequence +by stripping the eighth bit and prefixing an +escape character (in effect, using escape as the \fImeta prefix\fP). +.TP +.B disable\-completion (Off) +If set to \fBOn\fP, readline will inhibit word completion. Completion +characters will be inserted into the line as if they had been +mapped to \fBself-insert\fP. +.TP +.B editing\-mode (emacs) +Controls whether readline begins with a set of key bindings similar +to \fIEmacs\fP or \fIvi\fP. +.B editing\-mode +can be set to either +.B emacs +or +.BR vi . +.TP +.B echo\-control\-characters (On) +When set to \fBOn\fP, on operating systems that indicate they support it, +readline echoes a character corresponding to a signal generated from the +keyboard. +.TP +.B enable\-keypad (Off) +When set to \fBOn\fP, readline will try to enable the application +keypad when it is called. Some systems need this to enable the +arrow keys. +.TP +.B enable\-meta\-key (On) +When set to \fBOn\fP, readline will try to enable any meta modifier +key the terminal claims to support when it is called. On many terminals, +the meta key is used to send eight-bit characters. +.TP +.B expand\-tilde (Off) +If set to \fBOn\fP, tilde expansion is performed when readline +attempts word completion. +.TP +.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 retrieved with \fBprevious-history\fP +or \fBnext-history\fP. +.TP +.B history\-size (0) +Set the maximum number of history entries saved in the history list. If +set to zero, the number of entries in the history list is not limited. +.TP +.B horizontal\-scroll\-mode (Off) +When set to \fBOn\fP, makes readline use a single line for display, +scrolling the input horizontally on a single screen line when it +becomes longer than the screen width rather than wrapping to a new line. +.TP +.B input\-meta (Off) +If set to \fBOn\fP, readline will enable eight-bit input (that is, +it will not strip the high bit from the characters it reads), +regardless of what the terminal claims it can support. The name +.B meta\-flag +is a synonym for this variable. +.TP +.B isearch\-terminators (``C\-[C\-J'') +The string of characters that should terminate an incremental +search without subsequently executing the character as a command. +If this variable has not been given a value, the characters +\fIESC\fP and \fIC\-J\fP will terminate an incremental search. +.TP +.B keymap (emacs) +Set the current readline keymap. The set of valid keymap names is +\fIemacs, emacs\-standard, emacs\-meta, emacs\-ctlx, vi, +vi\-command\fP, and +.IR vi\-insert . +\fIvi\fP is equivalent to \fIvi\-command\fP; \fIemacs\fP is +equivalent to \fIemacs\-standard\fP. The default value is +.IR emacs ; +the value of +.B editing\-mode +also affects the default keymap. +.TP +.B mark\-directories (On) +If set to \fBOn\fP, completed directory names have a slash +appended. +.TP +.B mark\-modified\-lines (Off) +If set to \fBOn\fP, history lines that have been modified are displayed +with a preceding asterisk (\fB*\fP). +.TP +.B mark\-symlinked\-directories (Off) +If set to \fBOn\fP, completed names which are symbolic links to directories +have a slash appended (subject to the value of +\fBmark\-directories\fP). +.TP +.B match\-hidden\-files (On) +This variable, when set to \fBOn\fP, causes readline to match files whose +names begin with a `.' (hidden files) when performing filename +completion. +If set to \fBOff\fP, the leading `.' must be +supplied by the user in the filename to be completed. +.TP +.B menu\-complete\-display\-prefix (Off) +If set to \fBOn\fP, menu completion displays the common prefix of the +list of possible completions (which may be empty) before cycling through +the list. +.TP +.B output\-meta (Off) +If set to \fBOn\fP, readline will display characters with the +eighth bit set directly rather than as a meta-prefixed escape +sequence. +.TP +.B page\-completions (On) +If set to \fBOn\fP, readline uses an internal \fImore\fP-like pager +to display a screenful of possible completions at a time. +.TP +.B print\-completions\-horizontally (Off) +If set to \fBOn\fP, readline will display completions with matches +sorted horizontally in alphabetical order, rather than down the screen. +.TP +.B revert\-all\-at\-newline (Off) +If set to \fBOn\fP, readline will undo all changes to history lines +before returning when \fBaccept\-line\fP is executed. By default, +history lines may be modified and retain individual undo lists across +calls to \fBreadline\fP. +.TP +.B show\-all\-if\-ambiguous (Off) +This alters the default behavior of the completion functions. If +set to +.BR On , +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 skip\-completed\-text (Off) +If set to \fBOn\fP, this alters the default completion behavior when +inserting a single match into the line. It's only active when +performing completion in the middle of a word. If enabled, readline +does not insert characters from the completion that match characters +after point in the word being completed, so portions of the word +following the cursor are not duplicated. +.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 +completions. +.PD +.SS "Readline Conditional Constructs" +.PP +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. +.IP \fB$if\fP +The +.B $if +construct allows bindings to be made based on the +editing mode, the terminal being used, or the application using +readline. The text of the test extends to the end of the line; +no characters are required to isolate it. +.RS +.IP \fBmode\fP +The \fBmode=\fP form of the \fB$if\fP directive is used to test +whether readline is in emacs or vi mode. +This may be used in conjunction +with the \fBset keymap\fP command, for instance, to set bindings in +the \fIemacs\-standard\fP and \fIemacs\-ctlx\fP keymaps only if +readline is starting out in emacs mode. +.IP \fBterm\fP +The \fBterm=\fP 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 +.B = +is tested against the both full name of the terminal and the portion +of the terminal name before the first \fB\-\fP. This allows +.I sun +to match both +.I sun +and +.IR sun\-cmd , +for instance. +.IP \fBapplication\fP +The \fBapplication\fP construct is used to include +application-specific settings. Each program using the readline +library sets the \fIapplication name\fP, and an initialization +file 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 \fBbash\fP: +.sp 1 +.RS +.nf +\fB$if\fP Bash +# Quote the current or previous word +"\eC\-xq": "\eeb\e"\eef\e"" +\fB$endif\fP +.fi +.RE +.RE +.IP \fB$endif\fP +This command, as seen in the previous example, terminates an +\fB$if\fP command. +.IP \fB$else\fP +Commands in this branch of the \fB$if\fP directive are executed if +the test fails. +.IP \fB$include\fP +This directive takes a single filename as an argument and reads commands +and bindings from that file. For example, the following directive +would read \fI/etc/inputrc\fP: +.sp 1 +.RS +.nf +\fB$include\fP \^ \fI/etc/inputrc\fP +.fi +.RE +.SS Searching +.PP +Readline provides commands for searching through the command history +(see +.SM +.B HISTORY +below) for lines containing a specified string. +There are two search modes: +.I incremental +and +.IR non-incremental . +.PP +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. +The characters present in the value of the \fBisearch-terminators\fP +variable are used to terminate an incremental search. +If that variable has not been assigned a value the Escape and +Control-J characters will terminate an incremental search. +Control-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. +.PP +To find other matching entries in the history list, type Control-S or +Control-R 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 \fInewline\fP will terminate the search and accept +the line, thereby executing the command from the history list. +.PP +Readline remembers the last incremental search string. If two +Control-Rs are typed without any intervening characters defining a +new search string, any remembered search string is used. +.PP +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. +.SS "Readline Command Names" +.PP +The following is a list of the names of the commands and the default +key sequences to which they are bound. +Command names without an accompanying key sequence are unbound by default. +In the following descriptions, \fIpoint\fP refers to the current cursor +position, and \fImark\fP refers to a cursor position saved by the +\fBset\-mark\fP command. +The text between the point and mark is referred to as the \fIregion\fP. +.SS Commands for Moving +.PP +.PD 0 +.TP +.B beginning\-of\-line (C\-a) +Move to the start of the current line. +.TP +.B end\-of\-line (C\-e) +Move to the end of the line. +.TP +.B forward\-char (C\-f) +Move forward a character. +.TP +.B backward\-char (C\-b) +Move back a character. +.TP +.B forward\-word (M\-f) +Move forward to the end of the next word. Words are composed of +alphanumeric characters (letters and digits). +.TP +.B backward\-word (M\-b) +Move back to the start of the current or previous word. +Words are composed of alphanumeric characters (letters and digits). +.TP +.B shell\-forward\-word +Move forward to the end of the next word. +Words are delimited by non-quoted shell metacharacters. +.TP +.B shell\-backward\-word +Move back to the start of the current or previous word. +Words are delimited by non-quoted shell metacharacters. +.TP +.B clear\-screen (C\-l) +Clear the screen leaving the current line at the top of the screen. +With an argument, refresh the current line without clearing the +screen. +.TP +.B redraw\-current\-line +Refresh the current line. +.PD +.SS Commands for Manipulating the History +.PP +.PD 0 +.TP +.B accept\-line (Newline, 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 state of the +.SM +.B HISTCONTROL +variable. If the line is a modified history +line, then restore the history line to its original state. +.TP +.B previous\-history (C\-p) +Fetch the previous command from the history list, moving back in +the list. +.TP +.B next\-history (C\-n) +Fetch the next command from the history list, moving forward in the +list. +.TP +.B beginning\-of\-history (M\-<) +Move to the first line in the history. +.TP +.B end\-of\-history (M\->) +Move to the end of the input history, i.e., the line currently being +entered. +.TP +.B 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. +.TP +.B forward\-search\-history (C\-s) +Search forward starting at the current line and moving `down' through +the history as necessary. This is an incremental search. +.TP +.B non\-incremental\-reverse\-search\-history (M\-p) +Search backward through the history starting at the current line +using a non-incremental search for a string supplied by the user. +.TP +.B non\-incremental\-forward\-search\-history (M\-n) +Search forward through the history using a non-incremental search for +a string supplied by the user. +.TP +.B 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. +.TP +.B 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. +.TP +.B 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 +.IR n , +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\-_\^) +Insert the last argument to the previous command (the last word of +the previous history entry). +With a numeric argument, behave exactly like \fByank\-nth\-arg\fP. +Successive calls to \fByank\-last\-arg\fP move back through the history +list, inserting the last word (or the word specified by the argument to +the first call) of each line in turn. +Any numeric argument supplied to these successive calls determines +the direction to move through the history. A negative argument switches +the direction through the history (back or forward). +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 +performs alias and history expansion as well as all of the shell +word expansions. See +.SM +.B HISTORY EXPANSION +below for a description of history expansion. +.TP +.B history\-expand\-line (M\-^) +Perform history expansion on the current line. +See +.SM +.B HISTORY EXPANSION +below for a description of history expansion. +.TP +.B magic\-space +Perform history expansion on the current line and insert a space. +See +.SM +.B HISTORY EXPANSION +below for a description of history expansion. +.TP +.B alias\-expand\-line +Perform alias expansion on the current line. +See +.SM +.B ALIASES +above for a description of alias expansion. +.TP +.B history\-and\-alias\-expand\-line +Perform history and alias expansion on the current line. +.TP +.B insert\-last\-argument (M\-.\^, M\-_\^) +A synonym for \fByank\-last\-arg\fP. +.TP +.B 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. +.TP +.B edit\-and\-execute\-command (C\-xC\-e) +Invoke an editor on the current command line, and execute the result as shell +commands. +\fBBash\fP attempts to invoke +.SM +.BR $VISUAL , +.SM +.BR $EDITOR , +and \fIemacs\fP as the editor, in that order. +.PD +.SS Commands for Changing Text +.PP +.PD 0 +.TP +.B 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 \fBdelete\-char\fP, +then return +.SM +.BR EOF . +.TP +.B backward\-delete\-char (Rubout) +Delete the character behind the cursor. When given a numeric argument, +save the deleted text on the kill ring. +.TP +.B 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. +.TP +.B quoted\-insert (C\-q, C\-v) +Add the next character typed to the line verbatim. This is +how to insert characters like \fBC\-q\fP, for example. +.TP +.B tab\-insert (C\-v TAB) +Insert a tab character. +.TP +.B self\-insert (a,\ b,\ A,\ 1,\ !,\ ...) +Insert the character typed. +.TP +.B transpose\-chars (C\-t) +Drag the character before point forward over the character at point, +moving point forward as well. +If point is at the end of the line, then this transposes +the two characters before point. +Negative arguments have no effect. +.TP +.B transpose\-words (M\-t) +Drag the word before point past the word after point, +moving point over that word as well. +If point is at the end of the line, this transposes +the last two words on the line. +.TP +.B upcase\-word (M\-u) +Uppercase the current (or following) word. With a negative argument, +uppercase the previous word, but do not move point. +.TP +.B downcase\-word (M\-l) +Lowercase the current (or following) word. With a negative argument, +lowercase the previous word, but do not move point. +.TP +.B capitalize\-word (M\-c) +Capitalize the current (or following) word. With a negative argument, +capitalize the previous word, but do not move point. +.TP +.B 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 +\fBemacs\fP mode; \fBvi\fP mode does overwrite differently. +Each call to \fIreadline()\fP starts in insert mode. +In overwrite mode, characters bound to \fBself\-insert\fP replace +the text at point rather than pushing the text to the right. +Characters bound to \fBbackward\-delete\-char\fP replace the character +before point with a space. By default, this command is unbound. +.PD +.SS Killing and Yanking +.PP +.PD 0 +.TP +.B kill\-line (C\-k) +Kill the text from point to the end of the line. +.TP +.B backward\-kill\-line (C\-x Rubout) +Kill backward to the beginning of the line. +.TP +.B unix\-line\-discard (C\-u) +Kill backward from point to the beginning of the line. +The killed text is saved on the kill-ring. +.\" There is no real difference between this and backward-kill-line +.TP +.B kill\-whole\-line +Kill all characters on the current line, no matter where point is. +.TP +.B 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 those used by \fBforward\-word\fP. +.TP +.B backward\-kill\-word (M\-Rubout) +Kill the word behind point. +Word boundaries are the same as those used by \fBbackward\-word\fP. +.TP +.B shell\-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 those used by \fBshell\-forward\-word\fP. +.TP +.B shell\-backward\-kill\-word (M\-Rubout) +Kill the word behind point. +Word boundaries are the same as those used by \fBshell\-backward\-word\fP. +.TP +.B 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. +.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 +.B kill\-region +Kill the text in the current region. +.TP +.B copy\-region\-as\-kill +Copy the text in the region to the kill buffer. +.TP +.B copy\-backward\-word +Copy the word before point to the kill buffer. +The word boundaries are the same as \fBbackward\-word\fP. +.TP +.B copy\-forward\-word +Copy the word following point to the kill buffer. +The word boundaries are the same as \fBforward\-word\fP. +.TP +.B yank (C\-y) +Yank the top of the kill ring into the buffer at point. +.TP +.B yank\-pop (M\-y) +Rotate the kill ring, and yank the new top. Only works following +.B yank +or +.BR yank\-pop . +.PD +.SS Numeric Arguments +.PP +.PD 0 +.TP +.B 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. +.TP +.B 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 +.B 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. +.PD +.SS Completing +.PP +.PD 0 +.TP +.B complete (TAB) +Attempt to perform completion on the text before point. +.B Bash +attempts completion treating the text as a variable (if the +text begins with \fB$\fP), username (if the text begins with +\fB~\fP), hostname (if the text begins with \fB@\fP), or +command (including aliases and functions) in turn. If none +of these produces a match, filename completion is attempted. +.TP +.B possible\-completions (M\-?) +List the possible completions of the text before point. +.TP +.B insert\-completions (M\-*) +Insert all completions of the text before point +that would have been generated by +\fBpossible\-completions\fP. +.TP +.B menu\-complete +Similar to \fBcomplete\fP, but replaces the word to be completed +with a single match from the list of possible completions. +Repeated execution of \fBmenu\-complete\fP 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 \fBbell\-style\fP) +and the original text is restored. +An argument of \fIn\fP moves \fIn\fP 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 \fBTAB\fP, but is unbound +by default. +.TP +.B menu\-complete\-backward +Identical to \fBmenu\-complete\fP, but moves backward through the list +of possible completions, as if \fBmenu\-complete\fP had been given a +negative argument. This command is unbound by default. +.TP +.B delete\-char\-or\-list +Deletes the character under the cursor if not at the beginning or +end of the line (like \fBdelete\-char\fP). +If at the end of the line, behaves identically to +\fBpossible\-completions\fP. +This command is unbound by default. +.TP +.B complete\-filename (M\-/) +Attempt filename completion on the text before point. +.TP +.B possible\-filename\-completions (C\-x /) +List the possible completions of the text before point, +treating it as a filename. +.TP +.B complete\-username (M\-~) +Attempt completion on the text before point, treating +it as a username. +.TP +.B possible\-username\-completions (C\-x ~) +List the possible completions of the text before point, +treating it as a username. +.TP +.B complete\-variable (M\-$) +Attempt completion on the text before point, treating +it as a shell variable. +.TP +.B possible\-variable\-completions (C\-x $) +List the possible completions of the text before point, +treating it as a shell variable. +.TP +.B complete\-hostname (M\-@) +Attempt completion on the text before point, treating +it as a hostname. +.TP +.B possible\-hostname\-completions (C\-x @) +List the possible completions of the text before point, +treating it as a hostname. +.TP +.B 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. +.TP +.B possible\-command\-completions (C\-x !) +List the possible completions of the text before point, +treating it as a command name. +.TP +.B 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. +.TP +.B dabbrev\-expand +Attempt menu completion on the text before point, comparing +the text against lines from the history list for possible +completion matches. +.TP +.B 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 +.B Brace Expansion +above). +.PD +.SS Keyboard Macros +.PP +.PD 0 +.TP +.B start\-kbd\-macro (C\-x (\^) +Begin saving the characters typed into the current keyboard macro. +.TP +.B end\-kbd\-macro (C\-x )\^) +Stop saving the characters typed into the current keyboard macro +and store the definition. +.TP +.B 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. +.PD +.SS Miscellaneous +.PP +.PD 0 +.TP +.B re\-read\-init\-file (C\-x C\-r) +Read in the contents of the \fIinputrc\fP file, and incorporate +any bindings or variable assignments found there. +.TP +.B abort (C\-g) +Abort the current editing command and +ring the terminal's bell (subject to the setting of +.BR bell\-style ). +.TP +.B do\-uppercase\-version (M\-a, M\-b, M\-\fIx\fP, ...) +If the metafied character \fIx\fP is lowercase, run the command +that is bound to the corresponding uppercase character. +.TP +.B prefix\-meta (ESC) +Metafy the next character typed. +.SM +.B ESC +.B f +is equivalent to +.BR Meta\-f . +.TP +.B undo (C\-_, C\-x C\-u) +Incremental undo, separately remembered for each line. +.TP +.B revert\-line (M\-r) +Undo all changes made to this line. This is like executing the +.B undo +command enough times to return the line to its initial state. +.TP +.B tilde\-expand (M\-&) +Perform tilde expansion on the current word. +.TP +.B set\-mark (C\-@, M\-) +Set the mark to the point. If a +numeric argument is supplied, the mark is set to that position. +.TP +.B 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. +.TP +.B 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. +.TP +.B 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. +.TP +.B skip\-csi\-sequence +Read enough characters to consume a multi-key sequence such as those +defined for keys like Home and End. Such sequences begin with a +Control Sequence Indicator (CSI), usually ESC\-[. If this sequence is +bound to "\e[", keys producing such sequences will have no effect +unless explicitly bound to a readline command, instead of inserting +stray characters into the editing buffer. This is unbound by default, +but usually bound to ESC\-[. +.TP +.B insert\-comment (M\-#) +Without a numeric argument, the value of the readline +.B 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 \fBcomment\-begin\fP, the value is inserted, otherwise +the characters in \fBcomment\-begin\fP 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 +\fBcomment\-begin\fP 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. +.TP +.B 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. +.TP +.B 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, an asterisk is appended before +pathname expansion. +.TP +.B glob\-list\-expansions (C\-x g) +The list of expansions that would have been generated by +.B glob\-expand\-word +is displayed, and the line is redrawn. +If a numeric argument is supplied, an asterisk is appended before +pathname expansion. +.TP +.B 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 \fIinputrc\fP file. +.TP +.B dump\-variables +Print all of the settable readline 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 \fIinputrc\fP file. +.TP +.B 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 \fIinputrc\fP file. +.TP +.B display\-shell\-version (C\-x C\-v) +Display version information about the current instance of +.BR bash . +.PD +.SS Programmable Completion +.PP +When word completion is attempted for an argument to a command for +which a completion specification (a \fIcompspec\fP) has been defined +using the \fBcomplete\fP builtin (see +.SM +.B "SHELL BUILTIN COMMANDS" +below), the programmable completion facilities are invoked. +.PP +First, the command name is identified. +If the command word is the empty string (completion attempted at the +beginning of an empty line), any compspec defined with +the \fB\-E\fP option to \fBcomplete\fP is used. +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. +If those searches do not result in a compspec, any compspec defined with +the \fB\-D\fP option to \fBcomplete\fP is used as the default. +.PP +Once a compspec has been found, it is used to generate the list of +matching words. +If a compspec is not found, the default \fBbash\fP completion as +described above under \fBCompleting\fP is performed. +.PP +First, the actions specified by the compspec are used. +Only matches which are prefixed by the word being completed are +returned. +When the +.B \-f +or +.B \-d +option is used for filename or directory name completion, the shell +variable +.SM +.B FIGNORE +is used to filter the matches. +.PP +Any completions specified by a pathname expansion pattern to the +\fB\-G\fP option are generated next. +The words generated by the pattern need not match the word +being completed. +The +.SM +.B GLOBIGNORE +shell variable is not used to filter the matches, but the +.SM +.B FIGNORE +variable is used. +.PP +Next, the string specified as the argument to the \fB\-W\fP option +is considered. +The string is first split using the characters in the +.SM +.B 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 under +.SM +.BR EXPANSION . +The results are split using the rules described above under +\fBWord Splitting\fP. +The results of the expansion are prefix-matched against the word being +completed, and the matching words become the possible completions. +.PP +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 +.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. +If a shell function is being invoked, the +.SM +.B COMP_WORDS +and +.SM +.B 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. +.PP +Any function specified with \fB\-F\fP is invoked first. +The function may use any of the shell facilities, including the +\fBcompgen\fP builtin described below, to generate the matches. +It must put the possible completions in the +.SM +.B COMPREPLY +array variable. +.PP +Next, any command specified with the \fB\-C\fP 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. +.PP +After all of the possible completions are generated, any filter +specified with the \fB\-X\fP option is applied to the list. +The filter is a pattern as used for pathname expansion; a \fB&\fP +in the pattern is replaced with the text of the word being completed. +A literal \fB&\fP 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 \fB!\fP negates the pattern; in this case any completion +not matching the pattern will be removed. +.PP +Finally, any prefix and suffix specified with the \fB\-P\fP and \fB\-S\fP +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. +.PP +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 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 +to completed names which are symbolic links to directories, subject to +the value of the \fBmark\-directories\fP readline variable, regardless +of the setting of the \fBmark-symlinked\-directories\fP readline variable. +.PP +There is some support for dynamically modifying completions. This is +most useful when used in combination with a default completion specified +with \fBcomplete -D\fP. +It's possible for shell functions executed as completion +handlers to indicate that completion should be retried by returning an +exit status of 124. If a shell function returns 124, and changes +the compspec associated with the command on which completion is being +attempted (supplied as the first argument when the function is executed), +programmable completion restarts from the beginning, with an +attempt to find a new compspec for that command. This allows a set of +completions to be built dynamically as completion is attempted, rather than +being loaded all at once. +.PP +For instance, assuming that there is a library of compspecs, each kept in a +file corresponding to the name of the command, the following default +completion function would load completions dynamically: +.PP +\f(CW_completion_loader() +.br +{ +.br + . "/etc/bash_completion.d/$1.sh" >/dev/null 2>&1 && return 124 +.br +} +.br +complete -D -F _completion_loader +.br +\fP +.SH HISTORY +When the +.B \-o history +option to the +.B set +builtin is enabled, the shell provides access to the +\fIcommand history\fP, +the list of commands previously typed. +The value of the +.SM +.B HISTSIZE +variable is used as the +number of commands to save in a history list. +The text of the last +.SM +.B HISTSIZE +commands (default 500) is saved. The shell +stores each command in the history list prior to parameter and +variable expansion (see +.SM +.B EXPANSION +above) but after history expansion is performed, subject to the +values of the shell variables +.SM +.B HISTIGNORE +and +.SM +.BR HISTCONTROL . +.PP +On startup, the history is initialized from the file named by +the variable +.SM +.B HISTFILE +(default \fI~/.bash_history\fP). +The file named by the value of +.SM +.B HISTFILE +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 +lines are copied from the history list to +.SM +.BR $HISTFILE . +If the +.B histappend +shell option is enabled +(see the description of +.B shopt +under +.SM +.B "SHELL BUILTIN COMMANDS" +below), the lines are appended to the history file, +otherwise the history file is overwritten. +If +.SM +.B HISTFILE +is unset, or if the history file is unwritable, the history is +not saved. +If the +.SM +.B 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 +lines. If +.SM +.B HISTFILESIZE +is not set, no truncation is performed. +.PP +The builtin command +.B fc +(see +.SM +.B SHELL BUILTIN COMMANDS +below) may be used to list or edit and re-execute a portion of +the history list. +The +.B 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. +.PP +The shell allows control over which commands are saved on the history +list. The +.SM +.B HISTCONTROL +and +.SM +.B HISTIGNORE +variables may be set to cause the shell to save only a subset of the +commands entered. +The +.B 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 +.B lithist +shell option causes the shell to save the command with embedded newlines +instead of semicolons. See the description of the +.B shopt +builtin below under +.SM +.B "SHELL BUILTIN COMMANDS" +for information on setting and unsetting shell options. +.SH "HISTORY EXPANSION" +.PP +The shell supports a history expansion feature that +is similar to the history expansion in +.BR csh. +This section describes what syntax features are available. This +feature is enabled by default for interactive shells, and can be +disabled using the +.B \+H +option to the +.B set +builtin command (see +.SM +.B SHELL BUILTIN COMMANDS +below). Non-interactive shells do not perform history expansion +by default. +.PP +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. +.PP +History expansion is performed immediately after a complete line +is read, before the shell breaks it into words. +It takes place in two parts. +The first is to determine which line from the history list +to use during substitution. +The second is to select portions of that line for inclusion into +the current one. +The line selected from the history is the \fIevent\fP, +and the portions of that line that are acted upon are \fIwords\fP. +Various \fImodifiers\fP are available to manipulate the selected words. +The line is broken into words in the same fashion as when reading input, +so that several \fImetacharacter\fP-separated words surrounded by +quotes are considered one word. +History expansions are introduced by the appearance of the +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. +If the +.B histverify +shell option is enabled (see the description of the +.B shopt +builtin below), and +.B readline +is being used, history substitutions are not immediately passed to +the shell parser. +Instead, the expanded line is reloaded into the +.B readline +editing buffer for further modification. +If +.B readline +is being used, and the +.B histreedit +shell option is enabled, a failed history substitution will be reloaded +into the +.B readline +editing buffer for correction. +The +.B \-p +option to the +.B history +builtin command may be used to see what a history expansion will +do before using it. +The +.B \-s +option to the +.B 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. +.PP +The shell allows control of the various characters used by the +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 +history list. +Unless the reference is absolute, events are relative to the current +position in the history list. +.PP +.PD 0 +.TP +.B ! +Start a history substitution, except when followed by a +.BR blank , +newline, carriage return, = +or ( (when the \fBextglob\fP shell option is enabled using +the \fBshopt\fP builtin). +.TP +.B !\fIn\fR +Refer to command line +.IR n . +.TP +.B !\-\fIn\fR +Refer to the current command minus +.IR n . +.TP +.B !! +Refer to the previous command. This is a synonym for `!\-1'. +.TP +.B !\fIstring\fR +Refer to the most recent command preceding the current position in the +history list starting with +.IR string . +.TP +.B !?\fIstring\fR\fB[?]\fR +Refer to the most recent command preceding the current postition in the +history list containing +.IR string . +The trailing \fB?\fP may be omitted if +.I string +is followed immediately by a newline. +.TP +.B \d\s+2^\s-2\u\fIstring1\fP\d\s+2^\s-2\u\fIstring2\fP\d\s+2^\s-2\u +Quick substitution. Repeat the previous command, replacing +.I string1 +with +.IR string2 . +Equivalent to +``!!:s/\fIstring1\fP/\fIstring2\fP/'' +(see \fBModifiers\fP below). +.TP +.B !# +The entire command line typed so far. +.PD +.SS Word Designators +.PP +Word designators are used to select desired words from the event. +A +.B : +separates the event specification from the word designator. +It may be omitted if the word designator begins with a +.BR ^ , +.BR $ , +.BR * , +.BR \- , +or +.BR % . +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. +.PP +.PD 0 +.TP +.B 0 (zero) +The zeroth word. For the shell, this is the command +word. +.TP +.I n +The \fIn\fRth word. +.TP +.B ^ +The first argument. That is, word 1. +.TP +.B $ +The last argument. +.TP +.B % +The word matched by the most recent `?\fIstring\fR?' search. +.TP +.I x\fB\-\fPy +A range of words; `\-\fIy\fR' abbreviates `0\-\fIy\fR'. +.TP +.B * +All of the words but the zeroth. This is a synonym +for `\fI1\-$\fP'. It is not an error to use +.B * +if there is just one +word in the event; the empty string is returned in that case. +.TP +.B x* +Abbreviates \fIx\-$\fP. +.TP +.B x\- +Abbreviates \fIx\-$\fP like \fBx*\fP, but omits the last word. +.PD +.PP +If a word designator is supplied without an event specification, the +previous command is used as the event. +.SS Modifiers +.PP +After the optional word designator, there may appear a sequence of +one or more of the following modifiers, each preceded by a `:'. +.PP +.PD 0 +.PP +.TP +.B h +Remove a trailing file name component, leaving only the head. +.TP +.B t +Remove all leading file name components, leaving the tail. +.TP +.B r +Remove a trailing suffix of the form \fI.xxx\fP, leaving the +basename. +.TP +.B e +Remove all but the trailing suffix. +.TP +.B p +Print the new command but do not execute it. +.TP +.B q +Quote the substituted words, escaping further substitutions. +.TP +.B x +Quote the substituted words as with +.BR q , +but break into words at +.B blanks +and newlines. +.TP +.B s/\fIold\fP/\fInew\fP/ +Substitute +.I new +for the first occurrence of +.I old +in the event line. Any delimiter can be used in place of /. The +final delimiter is optional if it is the last character of the +event line. The delimiter may be quoted in +.I old +and +.I new +with a single backslash. If & appears in +.IR new , +it is replaced by +.IR old . +A single backslash will quote the &. If +.I old +is null, it is set to the last +.I old +substituted, or, if no previous history substitutions took place, +the last +.I string +in a +.B !?\fIstring\fR\fB[?]\fR +search. +.TP +.B & +Repeat the previous substitution. +.TP +.B g +Cause changes to be applied over the entire event line. This is +used in conjunction with `\fB:s\fP' (e.g., `\fB:gs/\fIold\fP/\fInew\fP/\fR') +or `\fB:&\fP'. If used with +`\fB:s\fP', any delimiter can be used +in place of /, and the final delimiter is optional +if it is the last character of the event line. +An \fBa\fP may be used as a synonym for \fBg\fP. +.TP +.B G +Apply the following `\fBs\fP' modifier once to each word in the event line. +.PD +.SH "SHELL BUILTIN COMMANDS" +.\" start of bash_builtins +.zZ +.PP +Unless otherwise noted, each builtin command documented in this +section as accepting options preceded by +.B \- +accepts +.B \-\- +to signify the end of the options. +The \fB:\fP, \fBtrue\fP, \fBfalse\fP, and \fBtest\fP builtins +do not accept options and do not treat \fB\-\-\fP specially. +The \fBexit\fP, \fBlogout\fP, \fBbreak\fP, \fBcontinue\fP, \fBlet\fP, +and \fBshift\fP builtins accept and process arguments beginning with +\fB\-\fP without requiring \fB\-\-\fP. +Other builtins that accept arguments but are not specified as accepting +options interpret arguments beginning with \fB\-\fP as invalid options and +require \fB\-\-\fP to prevent this interpretation. +.sp .5 +.PD 0 +.TP +\fB:\fP [\fIarguments\fP] +.PD +No effect; the command does nothing beyond expanding +.I arguments +and performing any specified +redirections. A zero exit code is returned. +.TP +\fB .\| \fP \fIfilename\fP [\fIarguments\fP] +.PD 0 +.TP +\fBsource\fP \fIfilename\fP [\fIarguments\fP] +.PD +Read and execute commands from +.I filename +in the current +shell environment and return the exit status of the last command +executed from +.IR filename . +If +.I filename +does not contain a slash, file names in +.SM +.B PATH +are used to find the directory containing +.IR filename . +The file searched for in +.SM +.B PATH +need not be executable. +When \fBbash\fP is not in \fIposix mode\fP, the current directory is +searched if no file is found in +.SM +.BR PATH . +If the +.B sourcepath +option to the +.B shopt +builtin command is turned off, the +.SM +.B PATH +is not searched. +If any \fIarguments\fP are supplied, they become the positional +parameters when \fIfilename\fP is executed. Otherwise the positional +parameters are unchanged. +The return status is the status of the last command exited within +the script (0 if no commands are executed), and false if +.I filename +is not found or cannot be read. +.TP +\fBalias\fP [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP] ...] +\fBAlias\fP with no arguments or with the +.B \-p +option prints the list of aliases in the form +\fBalias\fP \fIname\fP=\fIvalue\fP on standard output. +When arguments are supplied, an alias is defined for +each \fIname\fP whose \fIvalue\fP is given. +A trailing space in \fIvalue\fP causes the next word to be +checked for alias substitution when the alias is expanded. +For each \fIname\fP in the argument list for which no \fIvalue\fP +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 each suspended job \fIjobspec\fP in the background, as if it +had been started with +.BR & . +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, 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 +.TP +\fBbind\fP [\fB\-m\fP \fIkeymap\fP] [\fB\-q\fP \fIfunction\fP] [\fB\-u\fP \fIfunction\fP] [\fB\-r\fP \fIkeyseq\fP] +.TP +\fBbind\fP [\fB\-m\fP \fIkeymap\fP] \fB\-f\fP \fIfilename\fP +.TP +\fBbind\fP [\fB\-m\fP \fIkeymap\fP] \fB\-x\fP \fIkeyseq\fP:\fIshell\-command\fP +.TP +\fBbind\fP [\fB\-m\fP \fIkeymap\fP] \fIkeyseq\fP:\fIfunction\-name\fP +.TP +\fBbind\fP \fIreadline\-command\fP +.PD +Display current +.B readline +key and function bindings, bind a key sequence to a +.B readline +function or macro, or set a +.B readline +variable. +Each non-option argument is a command as it would appear in +.IR .inputrc , +but each binding or command must be passed as a separate argument; +e.g., '"\eC\-x\eC\-r": re\-read\-init\-file'. +Options, if supplied, have the following meanings: +.RS +.PD 0 +.TP +.B \-m \fIkeymap\fP +Use +.I keymap +as the keymap to be affected by the subsequent bindings. +Acceptable +.I keymap +names are +\fIemacs, emacs\-standard, emacs\-meta, emacs\-ctlx, vi, +vi\-move, vi\-command\fP, and +.IR vi\-insert . +\fIvi\fP is equivalent to \fIvi\-command\fP; \fIemacs\fP is +equivalent to \fIemacs\-standard\fP. +.TP +.B \-l +List the names of all \fBreadline\fP functions. +.TP +.B \-p +Display \fBreadline\fP function names and bindings in such a way +that they can be re-read. +.TP +.B \-P +List current \fBreadline\fP function names and bindings. +.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. +.TP +.B \-S +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 +.B \-q \fIfunction\fP +Query about which keys invoke the named \fIfunction\fP. +.TP +.B \-u \fIfunction\fP +Unbind all keys bound to the named \fIfunction\fP. +.TP +.B \-r \fIkeyseq\fP +Remove any current binding for \fIkeyseq\fP. +.TP +.B \-x \fIkeyseq\fP:\fIshell\-command\fP +Cause \fIshell\-command\fP to be executed whenever \fIkeyseq\fP is +entered. +When \fIshell\-command\fP is executed, the shell sets the +.SM +.B READLINE_LINE +variable to the contents of the \fBreadline\fP line buffer and the +.SM +.B READLINE_POINT +variable to the current location of the insertion point. +If the executed command changes the value of +.SM +.B READLINE_LINE +or +.SM +.BR READLINE_POINT , +those new values will be reflected in the editing state. +.PD +.PP +The return value is 0 unless an unrecognized option is given or an +error occurred. +.RE +.TP +\fBbreak\fP [\fIn\fP] +Exit from within a +.BR for , +.BR while , +.BR until , +or +.B select +loop. If \fIn\fP is specified, break \fIn\fP levels. +.I n +must be \(>= 1. If +.I n +is greater than the number of enclosing loops, all enclosing loops +are exited. +The return value is 0 unless \fIn\fP is not greater than or equal to 1. +.TP +\fBbuiltin\fP \fIshell\-builtin\fP [\fIarguments\fP] +Execute the specified shell builtin, passing it +.IR arguments , +and return its exit status. +This is useful when defining a +function whose name is the same as a shell builtin, +retaining the functionality of the builtin within the function. +The \fBcd\fP builtin is commonly redefined this way. +The return status is false if +.I shell\-builtin +is not a shell builtin command. +.TP +\fBcaller\fP [\fIexpr\fP] +Returns the context of any active subroutine call (a shell function or +a script executed with the \fB.\fP or \fBsource\fP builtins). +Without \fIexpr\fP, \fBcaller\fP displays the line number and source +filename of the current subroutine call. +If a non-negative integer is supplied as \fIexpr\fP, \fBcaller\fP +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 \fIexpr\fP does not correspond to a valid position in the +call stack. +.TP +\fBcd\fP [\fB\-L\fP|[\fB\-P\fP [\fB\-e\fP]]] [\fIdir\fP] +Change the current directory to \fIdir\fP. The variable +.SM +.B HOME +is the +default +.IR dir . +The variable +.SM +.B CDPATH +defines the search path for the directory containing +.IR dir . +Alternative directory names in +.SM +.B CDPATH +are separated by a colon (:). A null directory name in +.SM +.B CDPATH +is the same as the current directory, i.e., ``\fB.\fP''. If +.I dir +begins with a slash (/), +then +.SM +.B CDPATH +is not used. The +.B \-P +option says to use the physical directory structure instead of +following symbolic links (see also the +.B \-P +option to the +.B set +builtin command); the +.B \-L +option forces symbolic links to be followed. +If the +.B \-e +option is supplied with +.BR \-P , +and the current working directory cannot be successfully determined +after a successful directory change, \fBcd\fP will return an unsuccessful +status. +An argument of +.B \- +is converted to +.SM +.B $OLDPWD +before the directory change is attempted. +If a non-empty directory name from +.SM +.B CDPATH +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 +\fBcommand\fP [\fB\-pVv\fP] \fIcommand\fP [\fIarg\fP ...] +Run +.I command +with +.I args +suppressing the normal shell function lookup. Only builtin +commands or commands found in the +.SM +.B PATH +are executed. If the +.B \-p +option is given, the search for +.I command +is performed using a default value for +.SM +.B PATH +that is guaranteed to find all of the standard utilities. +If either the +.B \-V +or +.B \-v +option is supplied, a description of +.I command +is printed. The +.B \-v +option causes a single word indicating the command or file name +used to invoke +.I command +to be displayed; the +.B \-V +option produces a more verbose description. +If the +.B \-V +or +.B \-v +option is supplied, the exit status is 0 if +.I command +was found, and 1 if not. If neither option is supplied and +an error occurred or +.I command +cannot be found, the exit status is 127. Otherwise, the exit status of the +.B command +builtin is the exit status of +.IR command . +.TP +\fBcompgen\fP [\fIoption\fP] [\fIword\fP] +Generate possible completion matches for \fIword\fP according to +the \fIoption\fPs, which may be any option accepted by the +.B complete +builtin with the exception of \fB\-p\fP and \fB\-r\fP, and write +the matches to the standard output. +When using the \fB\-F\fP or \fB\-C\fP options, the various shell variables +set by the programmable completion facilities, while available, will not +have useful values. +.sp 1 +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 \fIword\fP is specified, only those completions matching \fIword\fP +will be displayed. +.sp 1 +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\-DE\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\-P\fP \fIprefix\fP] [\fB\-S\fP \fIsuffix\fP] \fIname\fP [\fIname ...\fP] +.PD 0 +.TP +\fBcomplete\fP \fB\-pr\fP [\fB\-DE\fP] [\fIname\fP ...] +.PD +Specify how arguments to each \fIname\fP should be completed. +If the \fB\-p\fP 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 \fB\-r\fP option removes a completion specification for +each \fIname\fP, or, if no \fIname\fPs are supplied, all +completion specifications. +The \fB\-D\fP option indicates that the remaining options and actions should +apply to the ``default'' command completion; that is, completion attempted +on a command for which no completion has previously been defined. +The \fB\-E\fP option indicates that the remaining options and actions should +apply to ``empty'' command completion; that is, completion attempted on a +blank line. +.sp 1 +The process of applying these completion specifications when word completion +is attempted is described above under \fBProgrammable Completion\fP. +.sp 1 +Other options, if specified, have the following meanings. +The arguments to the \fB\-G\fP, \fB\-W\fP, and \fB\-X\fP options +(and, if necessary, the \fB\-P\fP and \fB\-S\fP options) +should be quoted to protect them from expansion before the +.B complete +builtin is invoked. +.RS +.PD 0 +.TP 8 +\fB\-o\fP \fIcomp-option\fP +The \fIcomp-option\fP controls several aspects of the compspec's behavior +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. +.TP 8 +.B dirnames +Perform directory name completion if the compspec generates no matches. +.TP 8 +.B filenames +Tell readline that the compspec generates filenames, so it can perform any +filename\-specific processing (like adding a slash to directory names, +quoting special characters, or suppressing trailing spaces). +Intended to be used with shell functions. +.TP 8 +.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 +The \fIaction\fP may be one of the following to generate a list of possible +completions: +.RS +.TP 8 +.B alias +Alias names. May also be specified as \fB\-a\fP. +.TP 8 +.B arrayvar +Array variable names. +.TP 8 +.B binding +\fBReadline\fP key binding names. +.TP 8 +.B builtin +Names of shell builtin commands. May also be specified as \fB\-b\fP. +.TP 8 +.B command +Command names. May also be specified as \fB\-c\fP. +.TP 8 +.B directory +Directory names. May also be specified as \fB\-d\fP. +.TP 8 +.B disabled +Names of disabled shell builtins. +.TP 8 +.B enabled +Names of enabled shell builtins. +.TP 8 +.B export +Names of exported shell variables. May also be specified as \fB\-e\fP. +.TP 8 +.B file +File names. May also be specified as \fB\-f\fP. +.TP 8 +.B function +Names of shell functions. +.TP 8 +.B group +Group names. May also be specified as \fB\-g\fP. +.TP 8 +.B helptopic +Help topics as accepted by the \fBhelp\fP builtin. +.TP 8 +.B hostname +Hostnames, as taken from the file specified by the +.SM +.B HOSTFILE +shell variable. +.TP 8 +.B job +Job names, if job control is active. May also be specified as \fB\-j\fP. +.TP 8 +.B keyword +Shell reserved words. May also be specified as \fB\-k\fP. +.TP 8 +.B running +Names of running jobs, if job control is active. +.TP 8 +.B service +Service names. May also be specified as \fB\-s\fP. +.TP 8 +.B setopt +Valid arguments for the \fB\-o\fP option to the \fBset\fP builtin. +.TP 8 +.B shopt +Shell option names as accepted by the \fBshopt\fP builtin. +.TP 8 +.B signal +Signal names. +.TP 8 +.B stopped +Names of stopped jobs, if job control is active. +.TP 8 +.B user +User names. May also be specified as \fB\-u\fP. +.TP 8 +.B variable +Names of all shell variables. May also be specified as \fB\-v\fP. +.RE +.TP 8 +\fB\-C\fP \fIcommand\fP +\fIcommand\fP is executed in a subshell environment, and its output is +used as the possible completions. +.TP 8 +\fB\-F\fP \fIfunction\fP +The shell function \fIfunction\fP is executed in the current shell +environment. +When it finishes, the possible completions are retrieved from the value +of the +.SM +.B COMPREPLY +array variable. +.TP 8 +\fB\-G\fP \fIglobpat\fP +The pathname expansion pattern \fIglobpat\fP is expanded to generate +the possible completions. +.TP 8 +\fB\-P\fP \fIprefix\fP +\fIprefix\fP is added at the beginning of each possible completion +after all other options have been applied. +.TP 8 +\fB\-S\fP \fIsuffix\fP +\fIsuffix\fP is appended to each possible completion +after all other options have been applied. +.TP 8 +\fB\-W\fP \fIwordlist\fP +The \fIwordlist\fP is split using the characters in the +.SM +.B 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. +.TP 8 +\fB\-X\fP \fIfilterpat\fP +\fIfilterpat\fP is a pattern as used for pathname expansion. +It is applied to the list of possible completions generated by the +preceding options and arguments, and each completion matching +\fIfilterpat\fP is removed from the list. +A leading \fB!\fP in \fIfilterpat\fP negates the pattern; in this +case, any completion not matching \fIfilterpat\fP is removed. +.PD +.PP +The return value is true unless an invalid option is supplied, an option +other than \fB\-p\fP or \fB\-r\fP is supplied without a \fIname\fP +argument, an attempt is made to remove a completion specification for +a \fIname\fP for which no specification exists, or +an error occurs adding a completion specification. +.RE +.TP +\fBcompopt\fP [\fB\-o\fP \fIoption\fP] [\fB\-DE\fP] [\fB+o\fP \fIoption\fP] [\fIname\fP] +Modify completion options for each \fIname\fP according to the +\fIoption\fPs, or for the +currently-executing completion if no \fIname\fPs are supplied. +If no \fIoption\fPs are given, display the completion options for each +\fIname\fP or the current completion. +The possible values of \fIoption\fP are those valid for the \fBcomplete\fP +builtin described above. +The \fB\-D\fP option indicates that the remaining options should +apply to the ``default'' command completion; that is, completion attempted +on a command for which no completion has previously been defined. +The \fB\-E\fP option indicates that the remaining options should +apply to ``empty'' command completion; that is, completion attempted on a +blank line. +.sp 1 +The return value is true unless an invalid option is supplied, an attempt +is made to modify the options for a \fIname\fP for which no completion +specification exists, or an output error occurs. +.TP +\fBcontinue\fP [\fIn\fP] +Resume the next iteration of the enclosing +.BR for , +.BR while , +.BR until , +or +.B select +loop. +If +.I n +is specified, resume at the \fIn\fPth enclosing loop. +.I n +must be \(>= 1. If +.I n +is greater than the number of enclosing loops, the last enclosing loop +(the ``top-level'' loop) is resumed. +The return value is 0 unless \fIn\fP is not greater than or equal to 1. +.TP +\fBdeclare\fP [\fB\-aAfFgilrtux\fP] [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP] ...] +.PD 0 +.TP +\fBtypeset\fP [\fB\-aAfFgilrtux\fP] [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP] ...] +.PD +Declare variables and/or give them attributes. +If no \fIname\fPs are given then display the values of variables. +The +.B \-p +option will display the attributes and values of each +.IR name . +When +.B \-p +is used with \fIname\fP arguments, additional options are ignored. +When +.B \-p +is supplied without \fIname\fP arguments, it will display the attributes +and values of all variables having the attributes specified by the +additional options. +If no other options are supplied with \fB\-p\fP, \fBdeclare\fP will display +the attributes and values of all shell variables. The \fB\-f\fP option +will restrict the display to shell functions. +The +.B \-F +option inhibits the display of function definitions; only the +function name and attributes are printed. +If the \fBextdebug\fP shell option is enabled using \fBshopt\fP, +the source file name and line number where the function is defined +are displayed as well. The +.B \-F +option implies +.BR \-f . +The +.B \-g +option forces variables to be created or modified at the global scope, +even when \fBdeclare\fP is executed in a shell function. +It is ignored in all other cases. +The following options can +be used to restrict output to variables with the specified attribute or +to give variables attributes: +.RS +.PD 0 +.TP +.B \-a +Each \fIname\fP is an indexed array variable (see +.B Arrays +above). +.TP +.B \-A +Each \fIname\fP is an associative array variable (see +.B Arrays +above). +.TP +.B \-f +Use function names only. +.TP +.B \-i +The variable is treated as an integer; arithmetic evaluation (see +.SM +.B "ARITHMETIC EVALUATION" +above) is performed when the variable is assigned a value. +.TP +.B \-l +When the variable is assigned a value, all upper-case characters are +converted to lower-case. +The upper-case attribute is disabled. +.TP +.B \-r +Make \fIname\fPs readonly. These names cannot then be assigned values +by subsequent assignment statements or unset. +.TP +.B \-t +Give each \fIname\fP the \fItrace\fP attribute. +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 \-u +When the variable is assigned a value, all lower-case characters are +converted to upper-case. +The lower-case attribute is disabled. +.TP +.B \-x +Mark \fIname\fPs for export to subsequent commands via the environment. +.PD +.PP +Using `+' instead of `\-' +turns off the attribute instead, +with the exceptions that \fB+a\fP +may not be used to destroy an array variable and \fB+r\fP will not +remove the readonly attribute. +When used in a function, makes each +\fIname\fP local, as with the +.B local +command, +unless the \fB\-g\fP option is supplied, +If a variable name is followed by =\fIvalue\fP, the value of +the variable is set to \fIvalue\fP. +The return value is 0 unless an invalid option is encountered, +an attempt is made to define a function using +.if n ``\-f foo=bar'', +.if t \f(CW\-f foo=bar\fP, +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 +.B Arrays +above), one of the \fInames\fP 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 \fB\-f\fP. +.RE +.TP +.B dirs [+\fIn\fP] [\-\fIn\fP] [\fB\-clpv\fP] +Without options, displays the list of currently remembered directories. +The default display is on a single line with directory names separated +by spaces. +Directories are added to the list with the +.B pushd +command; the +.B popd +command removes entries from the list. +.RS +.PD 0 +.TP +\fB+\fP\fIn\fP +Displays the \fIn\fPth entry counting from the left of the list +shown by +.B dirs +when invoked without options, starting with zero. +.TP +\fB\-\fP\fIn\fP +Displays the \fIn\fPth entry counting from the right of the list +shown by +.B dirs +when invoked without options, starting with zero. +.TP +.B \-c +Clears the directory stack by deleting all of the entries. +.TP +.B \-l +Produces a longer listing; the default listing format uses a +tilde to denote the home directory. +.TP +.B \-p +Print the directory stack with one entry per line. +.TP +.B \-v +Print the directory stack with one entry per line, +prefixing each entry with its index in the stack. +.PD +.PP +The return value is 0 unless an +invalid option is supplied or \fIn\fP indexes beyond the end +of the directory stack. +.RE +.TP +\fBdisown\fP [\fB\-ar\fP] [\fB\-h\fP] [\fIjobspec\fP ...] +Without options, each +.I jobspec +is removed from the table of active jobs. +If +.I jobspec +is not present, and neither \fB\-a\fP 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 +.SM +.B SIGHUP +is not sent to the job if the shell receives a +.SM +.BR SIGHUP . +If no +.I jobspec +is present, and neither the +.B \-a +nor the +.B \-r +option is supplied, the \fIcurrent job\fP is used. +If no +.I jobspec +is supplied, the +.B \-a +option means to remove or mark all jobs; the +.B \-r +option without a +.I jobspec +argument restricts operation to running jobs. +The return value is 0 unless a +.I jobspec +does not specify a valid job. +.TP +\fBecho\fP [\fB\-neE\fP] [\fIarg\fP ...] +Output the \fIarg\fPs, separated by spaces, followed by a newline. +The return status is 0 unless a write error occurs. +If \fB\-n\fP is specified, the trailing newline is +suppressed. If the \fB\-e\fP option is given, interpretation of +the following backslash-escaped characters is enabled. The +.B \-E +option disables the interpretation of these escape characters, +even on systems where they are interpreted by default. +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 \fB\-\-\fP to mean the end of options. +.B echo +interprets the following escape sequences: +.RS +.PD 0 +.TP +.B \ea +alert (bell) +.TP +.B \eb +backspace +.TP +.B \ec +suppress further output +.TP +.B \ee +.TP +.B \eE +an escape character +.TP +.B \ef +form feed +.TP +.B \en +new line +.TP +.B \er +carriage return +.TP +.B \et +horizontal tab +.TP +.B \ev +vertical tab +.TP +.B \e\e +backslash +.TP +.B \e0\fInnn\fP +the eight-bit character whose value is the octal value \fInnn\fP +(zero 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) +.TP +.B \eu\fIHHHH\fP +the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value +\fIHHHH\fP (one to four hex digits) +.TP +.B \eU\fIHHHHHHHH\fP +the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value +\fIHHHHHHHH\fP (one to eight hex digits) +.PD +.RE +.TP +\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, +even though the shell normally searches for builtins before disk commands. +If \fB\-n\fP is used, each \fIname\fP +is disabled; otherwise, +\fInames\fP are enabled. For example, to use the +.B test +binary found via the +.SM +.B PATH +instead of the shell builtin version, run +.if t \f(CWenable -n test\fP. +.if n ``enable -n test''. +The +.B \-f +option means to load the new builtin command +.I name +from shared object +.IR filename , +on systems that support dynamic loading. The +.B \-d +option will delete a builtin previously loaded with +.BR \-f . +If no \fIname\fP arguments are given, or if the +.B \-p +option is supplied, a list of shell builtins is printed. +With no other option arguments, the list consists of all enabled +shell builtins. +If \fB\-n\fP is supplied, only disabled builtins are printed. +If \fB\-a\fP is supplied, the list printed includes all builtins, with an +indication of whether or not each is enabled. +If \fB\-s\fP is supplied, the output is restricted to the POSIX +\fIspecial\fP builtins. +The return value is 0 unless a +.I name +is not a shell builtin or there is an error loading a new builtin +from a shared object. +.TP +\fBeval\fP [\fIarg\fP ...] +The \fIarg\fPs are read and concatenated together into a single +command. This command is then read and executed by the shell, and +its exit status is returned as the value of +.BR eval . +If there are no +.IR args , +or only null arguments, +.B eval +returns 0. +.TP +\fBexec\fP [\fB\-cl\fP] [\fB\-a\fP \fIname\fP] [\fIcommand\fP [\fIarguments\fP]] +If +.I command +is specified, it replaces the shell. +No new process is created. The +.I arguments +become the arguments to \fIcommand\fP. +If the +.B \-l +option is supplied, +the shell places a dash at the beginning of the zeroth argument passed to +.IR command . +This is what +.IR login (1) +does. The +.B \-c +option causes +.I command +to be executed with an empty environment. If +.B \-a +is supplied, the shell passes +.I name +as the zeroth argument to the executed command. If +.I command +cannot be executed for some reason, a non-interactive shell exits, +unless the shell option +.B execfail +is enabled, in which case it returns failure. +An interactive shell returns failure if the file cannot be executed. +If +.I command +is not specified, any redirections take effect in the current shell, +and the return status is 0. If there is a redirection error, the +return status is 1. +.TP +\fBexit\fP [\fIn\fP] +Cause the shell to exit +with a status of \fIn\fP. If +.I n +is omitted, the exit status +is that of the last command executed. +A trap on +.SM +.B EXIT +is executed before the shell terminates. +.TP +\fBexport\fP [\fB\-fn\fP\^] [\fIname\fP[=\fIword\fP]] ... +.PD 0 +.TP +.B export \-p +.PD +The supplied +.I names +are marked for automatic export to the environment of +subsequently executed commands. If the +.B \-f +option is given, +the +.I names +refer to functions. +If no +.I names +are given, or if the +.B \-p +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 each +\fIname\fP. +If a variable name is followed by =\fIword\fP, the value of +the variable is set to \fIword\fP. +.B export +returns an exit status of 0 unless an invalid option is +encountered, +one of the \fInames\fP is not a valid shell variable name, or +.B \-f +is supplied with a +.I name +that is not a function. +.TP +\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] +.PD +Fix Command. In the first form, a range of commands from +.I first +to +.I last +is selected from the history list. +.I First +and +.I last +may be specified as a string (to locate the last 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 +.I last +is not specified it is set to +the current command for listing (so that +.if n ``fc \-l \-10'' +.if t \f(CWfc \-l \-10\fP +prints the last 10 commands) and to +.I first +otherwise. +If +.I first +is not specified it is set to the previous +command for editing and \-16 for listing. +.sp 1 +The +.B \-n +option suppresses +the command numbers when listing. The +.B \-r +option reverses the order of +the commands. If the +.B \-l +option is given, +the commands are listed on +standard output. Otherwise, the editor given by +.I ename +is invoked +on a file containing those commands. If +.I ename +is not given, the +value of the +.SM +.B FCEDIT +variable is used, and +the value of +.SM +.B EDITOR +if +.SM +.B FCEDIT +is not set. If neither variable is set, +.FN vi +is used. When editing is complete, the edited commands are +echoed and executed. +.sp 1 +In the second form, \fIcommand\fP is re-executed after each instance +of \fIpat\fP is replaced by \fIrep\fP. +A useful alias to use with this is +.if n ``r="fc -s"'', +.if t \f(CWr='fc \-s'\fP, +so that typing +.if n ``r cc'' +.if t \f(CWr cc\fP +runs the last command beginning with +.if n ``cc'' +.if t \f(CWcc\fP +and typing +.if n ``r'' +.if t \f(CWr\fP +re-executes the last command. +.sp 1 +If the first form is used, the return value is 0 unless an invalid +option is encountered or +.I first +or +.I last +specify history lines out of range. +If the +.B \-e +option is supplied, the return value is the value of the last +command executed or failure if an error occurs with the temporary +file of commands. If the second form is used, the return status +is that of the command re-executed, unless +.I cmd +does not specify a valid history line, in which case +.B fc +returns failure. +.TP +\fBfg\fP [\fIjobspec\fP] +Resume +.I jobspec +in the foreground, and make it the current job. +If +.I jobspec +is not present, the shell's notion of the \fIcurrent job\fP is used. +The return value is that of the command placed into the foreground, +or failure if run when job control is disabled or, when run with +job control enabled, if +.I jobspec +does not specify a valid job or +.I jobspec +specifies a job that was started without job control. +.TP +\fBgetopts\fP \fIoptstring\fP \fIname\fP [\fIargs\fP] +.B getopts +is used by shell procedures to parse positional parameters. +.I 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 characters may not be used as +option characters. +Each time it is invoked, +.B getopts +places the next option in the shell variable +.IR name , +initializing +.I name +if it does not exist, +and the index of the next argument to be processed into the +variable +.SM +.BR OPTIND . +.SM +.B OPTIND +is initialized to 1 each time the shell or a shell script +is invoked. When an option requires an argument, +.B getopts +places that argument into the variable +.SM +.BR OPTARG . +The shell does not reset +.SM +.B OPTIND +automatically; it must be manually reset between multiple +calls to +.B getopts +within the same shell invocation if a new set of parameters +is to be used. +.sp 1 +When the end of options is encountered, \fBgetopts\fP exits with a +return value greater than zero. +.SM +.B OPTIND +is set to the index of the first non-option argument, +and \fIname\fP is set to ?. +.sp 1 +.B getopts +normally parses the positional parameters, but if more arguments are +given in +.IR args , +.B getopts +parses those instead. +.sp 1 +.B getopts +can report errors in two ways. If the first character of +.I optstring +is a colon, +.I silent +error reporting is used. In normal operation diagnostic messages +are printed when invalid options or missing option arguments are +encountered. +If the variable +.SM +.B OPTERR +is set to 0, no error messages will be displayed, even if the first +character of +.I optstring +is not a colon. +.sp 1 +If an invalid option is seen, +.B getopts +places ? into +.I name +and, if not silent, +prints an error message and unsets +.SM +.BR OPTARG . +If +.B getopts +is silent, +the option character found is placed in +.SM +.B OPTARG +and no diagnostic message is printed. +.sp 1 +If a required argument is not found, and +.B getopts +is not silent, +a question mark (\^\fB?\fP\^) is placed in +.IR name , +.SM +.B OPTARG +is unset, and a diagnostic message is printed. +If +.B getopts +is silent, then a colon (\^\fB:\fP\^) is placed in +.I name +and +.SM +.B OPTARG +is set to the option character found. +.sp 1 +.B getopts +returns true if an option, specified or unspecified, is found. +It returns false if the end of options is encountered or an +error occurs. +.TP +\fBhash\fP [\fB\-lr\fP] [\fB\-p\fP \fIfilename\fP] [\fB\-dt\fP] [\fIname\fP] +Each time \fBhash\fP is invoked, +the full pathname of the command +.I name +is determined by searching +the directories in +.B $PATH +and remembered. Any previously-remembered pathname is discarded. +If the +.B \-p +option is supplied, no path search is performed, and +.I filename +is used as the full file name of the command. +The +.B \-r +option causes the shell to forget all +remembered locations. +The +.B \-d +option causes the shell to forget the remembered location of each \fIname\fP. +If the +.B \-t +option is supplied, the full pathname to which each \fIname\fP corresponds +is printed. If multiple \fIname\fP arguments are supplied with \fB\-t\fP, +the \fIname\fP is printed before the hashed full pathname. +The +.B \-l +option causes output to be displayed in a format that may be reused as input. +If no arguments are given, or if only \fB\-l\fP is supplied, +information about remembered commands is printed. +The return status is true unless a +.I name +is not found or an invalid option is supplied. +.TP +\fBhelp\fP [\fB\-dms\fP] [\fIpattern\fP] +Display helpful information about builtin commands. If +.I pattern +is specified, +.B help +gives detailed help on all commands matching +.IR pattern ; +otherwise help for all the builtins and shell control structures +is printed. +.RS +.PD 0 +.TP +.B \-d +Display a short description of each \fIpattern\fP +.TP +.B \-m +Display the description of each \fIpattern\fP in a manpage-like format +.TP +.B \-s +Display only a short usage synopsis for each \fIpattern\fP +.PD +.PP +The return status is 0 unless no command matches +.IR pattern . +.RE +.TP +\fBhistory [\fIn\fP] +.PD 0 +.TP +\fBhistory\fP \fB\-c\fP +.TP +\fBhistory \-d\fP \fIoffset\fP +.TP +\fBhistory\fP \fB\-anrw\fP [\fIfilename\fP] +.TP +\fBhistory\fP \fB\-p\fP \fIarg\fP [\fIarg ...\fP] +.TP +\fBhistory\fP \fB\-s\fP \fIarg\fP [\fIarg ...\fP] +.PD +With no options, display the command +history list with line numbers. Lines listed +with a +.B * +have been modified. An argument of +.I n +lists only the last +.I n +lines. +If the shell variable +.SM +.B HISTTIMEFORMAT +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 +is used. Options, if supplied, have the following meanings: +.RS +.PD 0 +.TP +.B \-c +Clear the history list by deleting all the entries. +.TP +\fB\-d\fP \fIoffset\fP +Delete the history entry at position \fIoffset\fP. +.TP +.B \-a +Append the ``new'' history lines (history lines entered since the +beginning of the current \fBbash\fP session) to the history file. +.TP +.B \-n +Read the history lines not already read from the history +file into the current history list. These are lines +appended to the history file since the beginning of the +current \fBbash\fP session. +.TP +.B \-r +Read the contents of the history file +and use them as the current history. +.TP +.B \-w +Write the current history to the history file, overwriting the +history file's contents. +.TP +.B \-p +Perform history substitution on the following \fIargs\fP and display +the result on the standard output. +Does not store the results in the history list. +Each \fIarg\fP must be quoted to disable normal history expansion. +.TP +.B \-s +Store the +.I args +in the history list as a single entry. The last command in the +history list is removed before the +.I args +are added. +.PD +.PP +If the +.SM +.B HISTTIMEFORMAT +variable is set, the time stamp information +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 +history expansion supplied as an argument to \fB\-p\fP fails. +.RE +.TP +\fBjobs\fP [\fB\-lnprs\fP] [ \fIjobspec\fP ... ] +.PD 0 +.TP +\fBjobs\fP \fB\-x\fP \fIcommand\fP [ \fIargs\fP ... ] +.PD +The first form lists the active jobs. The options have the following +meanings: +.RS +.PD 0 +.TP +.B \-l +List process IDs +in addition to the normal information. +.TP +.B \-n +Display information only about jobs that have changed status since +the user was last notified of their status. +.TP +.B \-p +List only the process ID of the job's process group +leader. +.TP +.B \-r +Restrict output to running jobs. +.TP +.B \-s +Restrict output to stopped jobs. +.PD +.PP +If +.I jobspec +is given, output is restricted to information about that job. +The return status is 0 unless an invalid option is encountered +or an invalid +.I jobspec +is supplied. +.PP +If the +.B \-x +option is supplied, +.B jobs +replaces any +.I jobspec +found in +.I command +or +.I args +with the corresponding process group ID, and executes +.I command +passing it +.IR args , +returning its exit status. +.RE +.TP +\fBkill\fP [\fB\-s\fP \fIsigspec\fP | \fB\-n\fP \fIsignum\fP | \fB\-\fP\fIsigspec\fP] [\fIpid\fP | \fIjobspec\fP] ... +.PD 0 +.TP +\fBkill\fP \fB\-l\fP [\fIsigspec\fP | \fIexit_status\fP] +.PD +Send the signal named by +.I sigspec +or +.I signum +to the processes named by +.I pid +or +.IR jobspec . +.I sigspec +is either a case-insensitive signal name such as +.SM +.B SIGKILL +(with or without the +.SM +.B SIG +prefix) or a signal number; +.I signum +is a signal number. +If +.I sigspec +is not present, then +.SM +.B SIGTERM +is assumed. +An argument of +.B \-l +lists the signal names. +If any arguments are supplied when +.B \-l +is given, the names of the signals corresponding to the arguments are +listed, and the return status is 0. +The \fIexit_status\fP argument to +.B \-l +is a number specifying either a signal number or the exit status of +a process terminated by a signal. +.B kill +returns true if at least one signal was successfully sent, or false +if an error occurs or an invalid option is encountered. +.TP +\fBlet\fP \fIarg\fP [\fIarg\fP ...] +Each +.I arg +is an arithmetic expression to be evaluated (see +.SM +.B "ARITHMETIC EVALUATION" +above). +If the last +.I arg +evaluates to 0, +.B let +returns 1; 0 is returned otherwise. +.TP +\fBlocal\fP [\fIoption\fP] [\fIname\fP[=\fIvalue\fP] ...] +For each argument, a local variable named +.I name +is created, and assigned +.IR value . +The \fIoption\fP can be any of the options accepted by \fBdeclare\fP. +When +.B local +is used within a function, it causes the variable +.I name +to have a visible scope restricted to that function and its children. +With no operands, +.B local +writes a list of local variables to the standard output. It is +an error to use +.B local +when not within a function. The return status is 0 unless +.B local +is used outside a function, an invalid +.I name +is supplied, or +\fIname\fP is a readonly variable. +.TP +.B logout +Exit a login shell. +.TP +\fBmapfile\fP [\fB\-n\fP \fIcount\fP] [\fB\-O\fP \fIorigin\fP] [\fB\-s\fP \fIcount\fP] [\fB\-t\fP] [\fB\-u\fP \fIfd\fP] [\fB\-C\fP \fIcallback\fP] [\fB\-c\fP \fIquantum\fP] [\fIarray\fP] +.PD 0 +.TP +\fBreadarray\fP [\fB\-n\fP \fIcount\fP] [\fB\-O\fP \fIorigin\fP] [\fB\-s\fP \fIcount\fP] [\fB\-t\fP] [\fB\-u\fP \fIfd\fP] [\fB\-C\fP \fIcallback\fP] [\fB\-c\fP \fIquantum\fP] [\fIarray\fP] +.PD +Read lines from the standard input into the indexed array variable +.IR array , +or from file descriptor +.IR fd +if the +.B \-u +option is supplied. +The variable +.SM +.B MAPFILE +is the default \fIarray\fP. +Options, if supplied, have the following meanings: +.RS +.PD 0 +.TP +.B \-n +Copy at most +.I count +lines. If \fIcount\fP is 0, all lines are copied. +.TP +.B \-O +Begin assigning to +.I array +at index +.IR origin . +The default index is 0. +.TP +.B \-s +Discard the first \fIcount\fP lines read. +.TP +.B \-t +Remove a trailing newline from each line read. +.TP +.B \-u +Read lines from file descriptor \fIfd\fP instead of the standard input. +.TP +.B \-C +Evaluate +.I callback +each time \fIquantum\fP lines are read. The \fB\-c\fP option specifies +.IR quantum . +.TP +.B \-c +Specify the number of lines read between each call to +.IR callback . +.PD +.PP +If +.B \-C +is specified without +.BR \-c , +the default quantum is 5000. +When \fIcallback\fP is evaluated, it is supplied the index of the next +array element to be assigned and the line to be assigned to that element +as additional arguments. +\fIcallback\fP is evaluated after the line is read but before the +array element is assigned. +.PP +If not supplied with an explicit origin, \fBmapfile\fP will clear \fIarray\fP +before assigning to it. +.PP +\fBmapfile\fP returns successfully unless an invalid option or option +argument is supplied, \fIarray\fP is invalid or unassignable, or if +\fIarray\fP is not an indexed array. +.RE +.TP +\fBpopd\fP [\-\fBn\fP] [+\fIn\fP] [\-\fIn\fP] +Removes entries from the directory stack. With no arguments, +removes the top directory from the stack, and performs a +.B cd +to the new top directory. +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 +.BR dirs , +starting with zero. For example: +.if n ``popd +0'' +.if t \f(CWpopd +0\fP +removes the first directory, +.if n ``popd +1'' +.if t \f(CWpopd +1\fP +the second. +.TP +\fB\-\fP\fIn\fP +Removes the \fIn\fPth entry counting from the right of the list +shown by +.BR dirs , +starting with zero. For example: +.if n ``popd -0'' +.if t \f(CWpopd -0\fP +removes the last directory, +.if n ``popd -1'' +.if t \f(CWpopd -1\fP +the next to last. +.PD +.PP +If the +.B popd +command is successful, a +.B dirs +is performed as well, and the return status is 0. +.B popd +returns false if an invalid option is encountered, the directory stack +is empty, a non-existent directory stack entry is specified, or the +directory change fails. +.RE +.TP +\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 \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 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 +\fIargument\fP. +In addition to the standard \fIprintf\fP(1) format specifications, +\fBprintf\fP interprets the following extensions: +.RS +.PD 0 +.TP +.B %b +causes +\fBprintf\fP to expand backslash escape sequences in 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). +.TP +.B %q +causes \fBprintf\fP to output the corresponding +\fIargument\fP in a format that can be reused as shell input. +.TP +.B %(\fIdatefmt\fP)T +causes \fBprintf\fP to output the date-time string resulting from using +\fIdatefmt\fP as a format string for \fIstrftime\fP(3). The corresponding +\fIargument\fP is an integer representing the number of seconds since the +epoch. Two special argument values may be used: -1 represents the current +time, and -2 represents the time the shell was invoked. +.PD +.PP +Arguments to non-string format specifiers are treated as C constants, +except that a leading plus or minus sign is allowed, and if the leading +character is a single or double quote, the value is the ASCII value of +the following character. +.PP +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. +.RE +.TP +\fBpushd\fP [\fB\-n\fP] [+\fIn\fP] [\-\fIn\fP] +.PD 0 +.TP +\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 +directory. With no arguments, exchanges the top two directories +and returns 0, unless the directory stack is empty. +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 +.BR dirs , +starting with zero) +is at the top. +.TP +\fB\-\fP\fIn\fP +Rotates the stack so that the \fIn\fPth directory +(counting from the right of the list shown by +.BR dirs , +starting with zero) is at the top. +.TP +.I dir +Adds +.I dir +to the directory stack at the top, making it the +new current working directory as if it had been supplied as the argument +to the \fBcd\fP builtin. +.PD +.PP +If the +.B pushd +command is successful, a +.B dirs +is performed as well. +If the first form is used, +.B pushd +returns 0 unless the cd to +.I dir +fails. With the second form, +.B pushd +returns 0 unless the directory stack is empty, +a non-existent directory stack element is specified, +or the directory change to the specified new current directory +fails. +.RE +.TP +\fBpwd\fP [\fB\-LP\fP] +Print the absolute pathname of the current working directory. +The pathname printed contains no symbolic links if the +.B \-P +option is supplied or the +.B \-o physical +option to the +.B set +builtin command is enabled. +If the +.B \-L +option is used, the pathname printed may contain symbolic links. +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\-a\fP \fIaname\fP] [\fB\-d\fP \fIdelim\fP] [\fB\-i\fP \fItext\fP] [\fB\-n\fP \fInchars\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 +.IR name , +the second word to the second +.IR name , +and so on, with leftover words and their intervening separators assigned +to the last +.IR name . +If there are fewer words read from the input stream than names, +the remaining names are assigned empty values. +The characters in +.SM +.B IFS +are used to split the line into words. +The backslash character (\fB\e\fP) may be used to remove any special +meaning for the next character read and for line continuation. +Options, if supplied, have the following meanings: +.RS +.PD 0 +.TP +.B \-a \fIaname\fP +The words are assigned to sequential indices +of the array variable +.IR aname , +starting at 0. +.I aname +is unset before any new values are assigned. +Other \fIname\fP arguments are ignored. +.TP +.B \-d \fIdelim\fP +The first character of \fIdelim\fP is used to terminate the input line, +rather than newline. +.TP +.B \-e +If the standard input +is coming from a terminal, +.B readline +(see +.SM +.B READLINE +above) is used to obtain the line. +Readline uses the current (or default, if line editing was not previously +active) editing settings. +.TP +.B \-i \fItext\fP +If +.B readline +is being used to read the line, \fItext\fP is placed into the editing +buffer before editing begins. +.TP +.B \-n \fInchars\fP +\fBread\fP returns after reading \fInchars\fP characters rather than +waiting for a complete line of input, but honor a delimiter if fewer +than \fInchars\fP characters are read before the delimiter. +.TP +.B \-N \fInchars\fP +\fBread\fP returns after reading exactly \fInchars\fP characters rather +than waiting for a complete line of input, unless EOF is encountered or +\fBread\fP times out. +Delimiter characters encountered in the input are +not treated specially and do not cause \fBread\fP to return until +\fInchars\fP characters are read. +.TP +.B \-p \fIprompt\fP +Display \fIprompt\fP on standard error, without a +trailing newline, before attempting to read any input. The prompt +is displayed only if input is coming from a terminal. +.TP +.B \-r +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. +.TP +.B \-s +Silent mode. If input is coming from a terminal, characters are +not echoed. +.TP +.B \-t \fItimeout\fP +Cause \fBread\fP to time out and return failure if a complete line of +input is not read within \fItimeout\fP seconds. +\fItimeout\fP may be a decimal number with a fractional portion following +the decimal point. +This option is only effective if \fBread\fP is reading input from a +terminal, pipe, or other special file; it has no effect when reading +from regular files. +If \fItimeout\fP is 0, \fBread\fP returns success if input is available on +the specified file descriptor, failure otherwise. +The exit status is greater than 128 if the timeout is exceeded. +.TP +.B \-u \fIfd\fP +Read input from file descriptor \fIfd\fP. +.PD +.PP +If no +.I names +are supplied, the line read is assigned to the variable +.SM +.BR REPLY . +The return code is zero, unless end-of-file is encountered, \fBread\fP +times out (in which case the return code is greater than 128), or an +invalid file descriptor is supplied as the argument to \fB\-u\fP. +.RE +.TP +\fBreadonly\fP [\fB\-aAf\fP] [\fB\-p\fP] [\fIname\fP[=\fIword\fP] ...] +.PD +The given +\fInames\fP are marked readonly; the values of these +.I names +may not be changed by subsequent assignment. +If the +.B \-f +option is supplied, the functions corresponding to the +\fInames\fP are so +marked. +The +.B \-a +option restricts the variables to indexed arrays; the +.B \-A +option restricts the variables to associative arrays. +If both options are supplied, +.B \-A +takes precedence. +If no +.I name +arguments are given, or if the +.B \-p +option is supplied, a list of all readonly names is printed. +The other options may be used to restrict the output to a subset of +the set of readonly names. +The +.B \-p +option causes output to be displayed in a format that +may be reused as input. +If a variable name is followed by =\fIword\fP, the value of +the variable is set to \fIword\fP. +The return status is 0 unless an invalid option is encountered, +one of the +.I names +is not a valid shell variable name, or +.B \-f +is supplied with a +.I name +that is not a function. +.TP +\fBreturn\fP [\fIn\fP] +Causes a function to exit with the return value specified by +.IR n . +If +.I n +is omitted, the return status is that of the last command +executed in the function body. If used outside a function, +but during execution of a script by the +.B . +(\fBsource\fP) command, it causes the shell to stop executing +that script and return either +.I n +or the exit status of the last command executed within the +script as the exit status of the script. If used outside a +function and not during execution of a script by \fB.\fP\^, +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\-\-abefhkmnptuvxBCEHPT\fP] [\fB\-o\fP \fIoption\-name\fP] [\fIarg\fP ...] +.PD 0 +.TP +\fBset\fP [\fB+abefhkmnptuvxBCEHPT\fP] [\fB+o\fP \fIoption\-name\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 +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 option processing are treated +as values for the positional parameters and are assigned, in order, to +.BR $1 , +.BR $2 , +.B ... +.BR $\fIn\fP . +Options, if specified, have the following meanings: +.RS +.PD 0 +.TP 8 +.B \-a +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 +immediately, rather than before the next primary prompt. This is +effective only when job control is enabled. +.TP 8 +.B \-e +Exit immediately if a \fIpipeline\fP (which may consist of a single +\fIsimple command\fP), a \fIsubshell\fP command enclosed in parentheses, +or one of the commands executed as part of a command list enclosed +by braces (see +.SM +.B SHELL GRAMMAR +above) exits with a non-zero status. +The shell does not exit if the +command that fails is part of the command list immediately following a +.B while +or +.B until +keyword, +part of the test following the +.B if +or +.B elif +reserved words, part of any command executed in a +.B && +or +.B || +list except the command following the final \fB&&\fP or \fB||\fP, +any command in a pipeline but the last, +or if the command's return value is +being inverted with +.BR ! . +A trap on \fBERR\fP, if set, is executed before the shell exits. +This option applies to the shell environment and each subshell environment +separately (see +.SM +.B "COMMAND EXECUTION ENVIRONMENT" +above), and may cause +subshells to exit before executing all the commands in the subshell. +.TP 8 +.B \-f +Disable pathname expansion. +.TP 8 +.B \-h +Remember the location of commands as they are looked up for execution. +This is enabled by default. +.TP 8 +.B \-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. +.TP 8 +.B \-m +Monitor mode. Job control is enabled. This option is on +by default for interactive shells on systems that support +it (see +.SM +.B JOB CONTROL +above). +All processes run in a separate process group. +When a background job completes, the shell prints a line +containing its exit status. +.TP 8 +.B \-n +Read commands but do not execute them. This may be used to +check a shell script for syntax errors. This is ignored by +interactive shells. +.TP 8 +.B \-o \fIoption\-name\fP +The \fIoption\-name\fP can be one of the following: +.RS +.TP 8 +.B allexport +Same as +.BR \-a . +.TP 8 +.B braceexpand +Same as +.BR \-B . +.TP 8 +.B emacs +Use an emacs-style command line editing interface. This is enabled +by default when the shell is interactive, unless the shell is started +with the +.B \-\-noediting +option. +This also affects the editing interface used for \fBread \-e\fP. +.TP 8 +.B errexit +Same as +.BR \-e . +.TP 8 +.B errtrace +Same as +.BR \-E . +.TP 8 +.B functrace +Same as +.BR \-T . +.TP 8 +.B hashall +Same as +.BR \-h . +.TP 8 +.B histexpand +Same as +.BR \-H . +.TP 8 +.B history +Enable command history, as described above under +.SM +.BR HISTORY . +This option is on by default in interactive shells. +.TP 8 +.B ignoreeof +The effect is as if the shell command +.if t \f(CWIGNOREEOF=10\fP +.if n ``IGNOREEOF=10'' +had been executed +(see +.B Shell Variables +above). +.TP 8 +.B keyword +Same as +.BR \-k . +.TP 8 +.B monitor +Same as +.BR \-m . +.TP 8 +.B noclobber +Same as +.BR \-C . +.TP 8 +.B noexec +Same as +.BR \-n . +.TP 8 +.B noglob +Same as +.BR \-f . +.TP 8 +.B nolog +Currently ignored. +.TP 8 +.B notify +Same as +.BR \-b . +.TP 8 +.B nounset +Same as +.BR \-u . +.TP 8 +.B onecmd +Same as +.BR \-t . +.TP 8 +.B physical +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 standard to match the standard (\fIposix mode\fP). +.TP 8 +.B privileged +Same as +.BR \-p . +.TP 8 +.B verbose +Same as +.BR \-v . +.TP 8 +.B vi +Use a vi-style command line editing interface. +This also affects the editing interface used for \fBread \-e\fP. +.TP 8 +.B xtrace +Same as +.BR \-x . +.sp .5 +.PP +If +.B \-o +is supplied with no \fIoption\-name\fP, the values of the current options are +printed. +If +.B +o +is supplied with no \fIoption\-name\fP, a series of +.B set +commands to recreate the current option settings is displayed on +the standard output. +.RE +.TP 8 +.B \-p +Turn on +.I privileged +mode. In this mode, the +.SM +.B $ENV +and +.SM +.B $BASH_ENV +files are not processed, shell functions are not inherited from the +environment, and the +.SM +.BR SHELLOPTS , +.SM +.BR BASHOPTS , +.SM +.BR CDPATH , +and +.SM +.B GLOBIGNORE +variables, if they appear in the environment, are ignored. +If the shell is started with the effective user (group) id not equal to the +real user (group) id, and the \fB\-p\fP option is not supplied, these actions +are taken and the effective user id is set to the real user id. +If the \fB\-p\fP 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. +.TP 8 +.B \-t +Exit after reading and executing one command. +.TP 8 +.B \-u +Treat unset variables and parameters other than the special +parameters "@" and "*" as an error when performing +parameter expansion. If expansion is attempted on an +unset variable or parameter, the shell prints an error message, and, +if not interactive, exits with a non-zero status. +.TP 8 +.B \-v +Print shell input lines as they are read. +.TP 8 +.B \-x +After expanding each \fIsimple command\fP, +\fBfor\fP command, \fBcase\fP command, \fBselect\fP command, or +arithmetic \fBfor\fP command, display the expanded value of +.SM +.BR PS4 , +followed by the command and its expanded arguments +or associated word list. +.TP 8 +.B \-B +The shell performs brace expansion (see +.B Brace Expansion +above). This is on by default. +.TP 8 +.B \-C +If set, +.B bash +does not overwrite an existing file with the +.BR > , +.BR >& , +and +.B <> +redirection operators. This may be overridden when +creating output files by using the redirection operator +.B >| +instead of +.BR > . +.TP 8 +.B \-E +If set, any trap on \fBERR\fP is inherited by shell functions, command +substitutions, and commands executed in a subshell environment. +The \fBERR\fP trap is normally not inherited in such cases. +.TP 8 +.B \-H +Enable +.B ! +style history substitution. This option is on by +default when the shell is interactive. +.TP 8 +.B \-P +If set, the shell does not follow symbolic links when executing +commands such as +.B cd +that change the current working directory. It uses the +physical directory structure instead. By default, +.B bash +follows the logical chain of directories when performing commands +which change the current directory. +.TP 8 +.B \-T +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 +unset. Otherwise, the positional parameters are set to the +\fIarg\fPs, even if some of them begin with a +.BR \- . +.TP 8 +.B \- +Signal the end of options, cause all remaining \fIarg\fPs to be +assigned to the positional parameters. The +.B \-x +and +.B \-v +options are turned off. +If there are no \fIarg\fPs, +the positional parameters remain unchanged. +.PD +.PP +The options are off by default unless otherwise noted. +Using + rather than \- causes these options to be turned off. +The options can also be specified as arguments to an invocation of +the shell. +The current set of options may be found in +.BR $\- . +The return status is always true unless an invalid option is encountered. +.RE +.TP +\fBshift\fP [\fIn\fP] +The positional parameters from \fIn\fP+1 ... are renamed to +.B $1 +.B .... +Parameters represented by the numbers \fB$#\fP +down to \fB$#\fP\-\fIn\fP+1 are unset. +.I n +must be a non-negative number less than or equal to \fB$#\fP. +If +.I n +is 0, no parameters are changed. +If +.I n +is not given, it is assumed to be 1. +If +.I n +is greater than \fB$#\fP, the positional parameters are not changed. +The return status is greater than zero if +.I n +is greater than +.B $# +or less than zero; otherwise 0. +.TP +\fBshopt\fP [\fB\-pqsu\fP] [\fB\-o\fP] [\fIoptname\fP ...] +Toggle the values of variables controlling optional shell behavior. +With no options, or with the +.B \-p +option, a list of all settable options is displayed, with +an indication of whether or not each is set. +The \fB\-p\fP option causes output to be displayed in a form that +may be reused as input. +Other options have the following meanings: +.RS +.PD 0 +.TP +.B \-s +Enable (set) each \fIoptname\fP. +.TP +.B \-u +Disable (unset) each \fIoptname\fP. +.TP +.B \-q +Suppresses normal output (quiet mode); the return status indicates +whether the \fIoptname\fP is set or unset. +If multiple \fIoptname\fP arguments are given with +.BR \-q , +the return status is zero if all \fIoptnames\fP are enabled; non-zero +otherwise. +.TP +.B \-o +Restricts the values of \fIoptname\fP to be those defined for the +.B \-o +option to the +.B set +builtin. +.PD +.PP +If either +.B \-s +or +.B \-u +is used with no \fIoptname\fP arguments, the display is limited to +those options which are set or unset, respectively. +Unless otherwise noted, the \fBshopt\fP options are disabled (unset) +by default. +.PP +The return status when listing options is zero if all \fIoptnames\fP +are enabled, non-zero otherwise. When setting or unsetting options, +the return status is zero unless an \fIoptname\fP is not a valid shell +option. +.PP +The list of \fBshopt\fP options is: +.if t .sp .5v +.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 +builtin command that +is not a directory is assumed to be the name of a variable whose +value is the directory to change to. +.TP 8 +.B cdspell +If set, minor errors in the spelling of a directory component in a +.B cd +command will be corrected. +The errors checked for are transposed characters, +a missing character, and one character too many. +If a correction is found, the corrected file name is printed, +and the command proceeds. +This option is only used by interactive shells. +.TP 8 +.B checkhash +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, \fBbash\fP 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 +.SM +.B "JOB CONTROL" +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 +.SM +.B LINES +and +.SM +.BR COLUMNS . +.TP 8 +.B cmdhist +If set, +.B 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. +.TP 8 +.B compat31 +If set, +.B bash +changes its behavior to that of version 3.1 with respect to quoted +arguments to the \fB[[\fP conditional command's \fB=~\fP operator. +.TP 8 +.B compat32 +If set, +.B bash +changes its behavior to that of version 3.2 with respect to locale-specific +string comparison when using the \fB[[\fP +conditional command's \fB<\fP and \fB>\fP operators. +Bash versions prior to bash-4.1 use ASCII collation and +.IR strcmp (3); +bash-4.1 and later +use the current locale's collation sequence and +.IR strcoll (3). +.TP 8 +.B compat40 +If set, +.B bash +changes its behavior to that of version 4.0 with respect to locale-specific +string comparison when using the \fB[[\fP +conditional command's \fB<\fP and \fB>\fP operators (see previous item) +and the effect of interrupting a command list. +.TP 8 +.B compat41 +If set, +.BR bash , +when in posix mode, treats a single quote in a double-quoted +parameter expansion as a special character. The single quotes must match +(an even number) and the characters between the single quotes are considered +quoted. This is the behavior of posix mode through version 4.1. +The default bash behavior remains as in previous versions. +.TP 8 +.B direxpand +If set, +.B bash +replaces directory names with the results of word expansion when performing +filename completion. This changes the contents of the readline editing +buffer. +If not set, +.B bash +attempts to preserve what the user typed. +.TP 8 +.B dirspell +If set, +.B bash +attempts spelling correction on directory names during word completion +if the directory name initially supplied does not exist. +.TP 8 +.B dotglob +If set, +.B bash +includes filenames beginning with a `.' in the results of pathname +expansion. +.TP 8 +.B execfail +If set, a non-interactive shell will not exit if +it cannot execute the file specified as an argument to the +.B exec +builtin command. An interactive shell does not exit if +.B exec +fails. +.TP 8 +.B expand_aliases +If set, aliases are expanded as described above under +.SM +.BR ALIASES . +This option is enabled by default for interactive shells. +.TP 8 +.B extdebug +If set, behavior intended for use by debuggers is enabled: +.RS +.TP +.B 1. +The \fB\-F\fP option to the \fBdeclare\fP builtin displays the source +file name and line number corresponding to each function name supplied +as an argument. +.TP +.B 2. +If the command run by the \fBDEBUG\fP trap returns a non-zero value, the +next command is skipped and not executed. +.TP +.B 3. +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. +.SM +.B BASH_ARGC +and +.SM +.B BASH_ARGV +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 +\fBERR\fP trap. +.RE +.TP 8 +.B extglob +If set, the extended pattern matching features described above under +\fBPathname Expansion\fP are enabled. +.TP 8 +.B extquote +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 +.SM +.B FIGNORE +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 +.SM +.BR FIGNORE . +This option is enabled by default. +.TP 8 +.B globasciiranges +If set, range expressions used in pattern matching (see +.SM +.B Pattern Matching +above) behave as if in the traditional C locale when performing +comparisons. That is, the current locale's collating sequence +is not taken into account, so +.B b +will not collate between +.B A +and +.BR B , +and upper-case and lower-case ASCII characters will collate together. +.TP 8 +.B globstar +If set, the pattern \fB**\fP used in a pathname expansion context will +match all files and zero or more directories and subdirectories. +If the pattern is followed by a \fB/\fP, only directories and +subdirectories match. +.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 +.SM +.B HISTFILE +variable when the shell exits, rather than overwriting the file. +.TP 8 +.B histreedit +If set, and +.B readline +is being used, a user is given the opportunity to re-edit a +failed history substitution. +.TP 8 +.B histverify +If set, and +.B 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 \fBreadline\fP editing buffer, allowing further modification. +.TP 8 +.B hostcomplete +If set, and +.B readline +is being used, \fBbash\fP will attempt to perform hostname completion when a +word containing a \fB@\fP is being completed (see +.B Completing +under +.SM +.B READLINE +above). +This is enabled by default. +.TP 8 +.B huponexit +If set, \fBbash\fP will send +.SM +.B SIGHUP +to all jobs when an interactive login shell exits. +.TP 8 +.B interactive_comments +If set, allow a word beginning with +.B # +to cause that word and all remaining characters on that +line to be ignored in an interactive shell (see +.SM +.B COMMENTS +above). This option is enabled by default. +.TP 8 +.B lastpipe +If set, and job control is not active, the shell runs the last command of +a pipeline not executed in the background in the current shell environment. +.TP 8 +.B lithist +If set, and the +.B cmdhist +option is enabled, multi-line commands are saved to the history with +embedded newlines rather than using semicolon separators where possible. +.TP 8 +.B login_shell +The shell sets this option if it is started as a login shell (see +.SM +.B "INVOCATION" +above). +The value may not be changed. +.TP 8 +.B mailwarn +If set, and a file that \fBbash\fP is checking for mail has been +accessed since the last time it was checked, the message ``The mail in +\fImailfile\fP has been read'' is displayed. +.TP 8 +.B no_empty_cmd_completion +If set, and +.B readline +is being used, +.B bash +will not attempt to search the +.SM +.B PATH +for possible completions when +completion is attempted on an empty line. +.TP 8 +.B nocaseglob +If set, +.B bash +matches filenames in a case\-insensitive fashion when performing pathname +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 +allows patterns which match no +files (see +.B Pathname Expansion +above) +to expand to a null string, rather than themselves. +.TP 8 +.B progcomp +If set, the programmable completion facilities (see +\fBProgrammable Completion\fP above) are enabled. +This option is enabled by default. +.TP 8 +.B promptvars +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. +.TP 8 +.B restricted_shell +The shell sets this option if it is started in restricted mode (see +.SM +.B "RESTRICTED SHELL" +below). +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. +.TP 8 +.B shift_verbose +If set, the +.B shift +builtin prints an error message when the shift count exceeds the +number of positional parameters. +.TP 8 +.B sourcepath +If set, the +\fBsource\fP (\fB.\fP) builtin uses the value of +.SM +.B PATH +to find the directory containing the file supplied as an argument. +This option is enabled by default. +.TP 8 +.B xpg_echo +If set, the \fBecho\fP builtin expands backslash-escape sequences +by default. +.RE +.PD +.TP +\fBsuspend\fP [\fB\-f\fP] +Suspend the execution of this shell until it receives a +.SM +.B SIGCONT +signal. A login shell cannot be suspended; the +.B \-f +option can be used to override this and force the suspension. +The return status is 0 unless the shell is a login shell and +.B \-f +is not supplied, or if job control is not enabled. +.TP +\fBtest\fP \fIexpr\fP +.PD 0 +.TP +\fB[\fP \fIexpr\fP \fB]\fP +Return a status of 0 or 1 depending on +the evaluation of the conditional expression +.IR expr . +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 +in decreasing order of precedence. +The evaluation depends on the number of arguments; see below. +Operator precedence is used when there are five or more arguments. +.RS +.PD 0 +.TP +.B ! \fIexpr\fP +True if +.I expr +is false. +.TP +.B ( \fIexpr\fP ) +Returns the value of \fIexpr\fP. +This may be used to override the normal precedence of operators. +.TP +\fIexpr1\fP \-\fBa\fP \fIexpr2\fP +True if both +.I expr1 +and +.I expr2 +are true. +.TP +\fIexpr1\fP \-\fBo\fP \fIexpr2\fP +True if either +.I expr1 +or +.I expr2 +is true. +.PD +.PP +\fBtest\fP and \fB[\fP evaluate conditional +expressions using a set of rules based on the number of arguments. +.if t .sp 0.5 +.if n .sp 1 +.PD 0 +.TP +0 arguments +The expression is false. +.TP +1 argument +The expression is true if and only if the argument is not null. +.TP +2 arguments +If the first argument is \fB!\fP, the expression is true if and +only if the second argument is null. +If the first argument is one of the unary conditional operators listed above +under +.SM +.BR "CONDITIONAL EXPRESSIONS" , +the expression is true if the unary test is true. +If the first argument is not a valid unary conditional operator, the expression +is false. +.TP +3 arguments +The following conditions are applied in the order listed. +If the second argument is one of the binary conditional operators listed above +under +.SM +.BR "CONDITIONAL EXPRESSIONS" , +the result of the expression is the result of the binary test using +the first and third arguments as operands. +The \fB\-a\fP and \fB\-o\fP operators are considered binary operators +when there are three arguments. +If the first argument is \fB!\fP, the value is the negation of +the two-argument test using the second and third arguments. +If the first argument is exactly \fB(\fP and the third argument is +exactly \fB)\fP, the result is the one-argument test of the second +argument. +Otherwise, the expression is false. +.TP +4 arguments +If the first argument is \fB!\fP, 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. +.TP +5 or more arguments +The expression is parsed and evaluated according to precedence +using the rules listed above. +.if t .sp 0.5 +.if n .sp 1 +.LP +When used with \fBtest\fP or \fB[\fP, the \fB<\fP and \fB>\fP operators +sort lexicographically using ASCII ordering. +.RE +.PD +.TP +.B times +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 ...] +The command +.I arg +is to be read and executed when the shell receives +signal(s) +.IR sigspec . +If +.I arg +is absent (and there is a single \fIsigspec\fP) or +.BR \- , +each specified signal is +reset to its original disposition (the value it had +upon entrance to the shell). +If +.I arg +is the null string the signal specified by each +.I sigspec +is ignored by the shell and by the commands it invokes. +If +.I arg +is not present and +.B \-p +has been supplied, then the trap commands associated with each +.I sigspec +are displayed. +If no arguments are supplied or if only +.B \-p +is given, +.B trap +prints the list of commands associated with each signal. +The +.B \-l +option causes the shell to print a list of signal names and +their corresponding numbers. +Each +.I sigspec +is either +a signal name defined in <\fIsignal.h\fP>, or a signal number. +Signal names are case insensitive and the +.SM +.B SIG +prefix is optional. +.if t .sp 0.5 +.if n .sp 1 +If a +.I sigspec +is +.SM +.B EXIT +(0) the command +.I arg +is executed on exit from the shell. +If a +.I sigspec +is +.SM +.BR DEBUG , +the command +.I arg +is executed before every \fIsimple command\fP, \fIfor\fP command, +\fIcase\fP command, \fIselect\fP command, every arithmetic \fIfor\fP +command, and before the first command executes in a shell function (see +.SM +.B SHELL GRAMMAR +above). +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 +is +.SM +.BR RETURN , +the command +.I arg +is executed each time a shell function or a script executed with +the \fB.\fP or \fBsource\fP builtins finishes executing. +.if t .sp 0.5 +.if n .sp 1 +If a +.I sigspec +is +.SM +.BR ERR , +the command +.I arg +is executed whenever a simple command has a non\-zero exit status, +subject to the following conditions. +The +.SM +.B ERR +trap is not executed if the failed +command is part of the command list immediately following a +.B while +or +.B until +keyword, +part of the test in an +.I if +statement, part of a command executed in a +.B && +or +.B || +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 t .sp 0.5 +.if n .sp 1 +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 subshell or subshell environment when one is created. +The return status is false if any +.I sigspec +is invalid; otherwise +.B trap +returns true. +.TP +\fBtype\fP [\fB\-aftpP\fP] \fIname\fP [\fIname\fP ...] +With no options, +indicate how each +.I name +would be interpreted if used as a command name. +If the +.B \-t +option is used, +.B type +prints a string which is one of +.IR alias , +.IR keyword , +.IR function , +.IR builtin , +or +.I file +if +.I name +is an alias, shell reserved word, function, builtin, or disk file, +respectively. +If the +.I name +is not found, then nothing is printed, and an exit status of false +is returned. +If the +.B \-p +option is used, +.B type +either returns the name of the disk file +that would be executed if +.I name +were specified as a command name, +or nothing if +.if t \f(CWtype -t name\fP +.if n ``type -t name'' +would not return +.IR file . +The +.B \-P +option forces a +.SM +.B PATH +search for each \fIname\fP, even if +.if t \f(CWtype -t name\fP +.if n ``type -t name'' +would not return +.IR file . +If a command is hashed, +.B \-p +and +.B \-P +print the hashed value, not necessarily the file that appears +first in +.SM +.BR PATH . +If the +.B \-a +option is used, +.B type +prints all of the places that contain +an executable named +.IR name . +This includes aliases and functions, +if and only if the +.B \-p +option is not also used. +The table of hashed commands is not consulted +when using +.BR \-a . +The +.B \-f +option suppresses shell function lookup, as with the \fBcommand\fP builtin. +.B type +returns true if all of the arguments are found, false if +any are not found. +.TP +\fBulimit\fP [\fB\-HSTabcdefilmnpqrstuvx\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 +set for the given resource. +A hard limit cannot be increased by a non-root user once it is set; +a soft limit may be increased up to the value of the hard limit. +If neither \fB\-H\fP nor \fB\-S\fP is specified, both the soft and hard +limits are set. +The value of +.I limit +can be a number in the unit specified for the resource +or one of the special values +.BR hard , +.BR soft , +or +.BR unlimited , +which stand for the current hard limit, the current soft limit, and +no limit, respectively. +If +.I limit +is omitted, the current value of the soft limit of the resource is +printed, unless the \fB\-H\fP option is given. When more than one +resource is specified, the limit name and unit are printed before the value. +Other options are interpreted as follows: +.RS +.PD 0 +.TP +.B \-a +All current limits are reported +.TP +.B \-b +The maximum socket buffer size +.TP +.B \-c +The maximum size of core files created +.TP +.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 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 +.TP +.B \-m +The maximum resident set size (many systems do not honor this limit) +.TP +.B \-n +The maximum number of open file descriptors (most systems do not +allow this value to be set) +.TP +.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 +.B \-t +The maximum amount of cpu time in seconds +.TP +.B \-u +The maximum number of processes available to a single user +.TP +.B \-v +The maximum amount of virtual memory available to the shell and, on +some systems, to its children +.TP +.B \-x +The maximum number of file locks +.TP +.B \-T +The maximum number of threads +.PD +.PP +If +.I limit +is given, it is the new value of the specified resource (the +.B \-a +option is display only). +If no option is given, then +.B \-f +is assumed. Values are in 1024-byte increments, except for +.BR \-t , +which is in seconds, +.BR \-p , +which is in units of 512-byte blocks, +and +.BR \-T , +.BR \-b , +.BR \-n , +and +.BR \-u , +which are unscaled values. +The return status is 0 unless an invalid option or argument is supplied, +or an error occurs while setting a new limit. +.RE +.TP +\fBumask\fP [\fB\-p\fP] [\fB\-S\fP] [\fImode\fP] +The user file-creation mask is set to +.IR mode . +If +.I mode +begins with a digit, it +is interpreted as an octal number; otherwise +it is interpreted as a symbolic mode mask similar +to that accepted by +.IR chmod (1). +If +.I mode +is omitted, the current value of the mask is printed. +The +.B \-S +option causes the mask to be printed in symbolic form; the +default output is an octal number. +If the +.B \-p +option is supplied, and +.I mode +is omitted, the output is in a form that may be reused as input. +The return status is 0 if the mode was successfully changed or if +no \fImode\fP argument was supplied, and false otherwise. +.TP +\fBunalias\fP [\-\fBa\fP] [\fIname\fP ...] +Remove each \fIname\fP from the list of defined aliases. If +.B \-a +is supplied, all alias definitions are removed. The return +value is true unless a supplied +.I name +is not a defined alias. +.TP +\fBunset\fP [\-\fBfv\fP] [\fIname\fP ...] +For each +.IR name , +remove the corresponding variable or function. +If the +.B \-v +option is given, each +.I name +refers to a shell variable, and that variable is removed. +Read-only variables may not be unset. +If +.B \-f +is specified, each +.I name +refers to a shell function, and the function definition +is removed. +If no options are supplied, each \fIname\fP refers to a variable; if +there is no variable by that name, any function with that name is +unset. +Each unset variable or function is removed from the environment +passed to subsequent commands. +If any of +.SM +.BR COMP_WORDBREAKS , +.SM +.BR RANDOM , +.SM +.BR SECONDS , +.SM +.BR LINENO , +.SM +.BR HISTCMD , +.SM +.BR FUNCNAME , +.SM +.BR GROUPS , +or +.SM +.B DIRSTACK +are unset, they lose their special properties, even if they are +subsequently reset. The exit status is true unless a +.I name +is readonly. +.TP +\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 +in that job's pipeline are waited for. If +.I n +is not given, all currently active child processes +are waited for, and the return status is zero. If +.I n +specifies a non-existent process or job, the return status is +127. Otherwise, the return status is the exit status of the last +process or job waited for. +.\" bash_builtins +.if \n(zZ=1 .ig zZ +.SH "RESTRICTED SHELL" +.\" rbash.1 +.zY +.PP +If +.B bash +is started with the name +.BR rbash , +or the +.B \-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. +It behaves identically to +.B bash +with the exception that the following are disallowed or not performed: +.IP \(bu +changing directories with \fBcd\fP +.IP \(bu +setting or unsetting the values of +.SM +.BR SHELL , +.SM +.BR PATH , +.SM +.BR ENV , +or +.SM +.B BASH_ENV +.IP \(bu +specifying command names containing +.B / +.IP \(bu +specifying a file name containing a +.B / +as an argument to the +.B . +builtin command +.IP \(bu +specifying a filename containing a slash as an argument to the +.B \-p +option to the +.B hash +builtin command +.IP \(bu +importing function definitions from the shell environment at startup +.IP \(bu +parsing the value of +.SM +.B SHELLOPTS +from the shell environment at startup +.IP \(bu +redirecting output using the >, >|, <>, >&, &>, and >> redirection operators +.IP \(bu +using the +.B exec +builtin command to replace the shell with another command +.IP \(bu +adding or deleting builtin commands with the +.B \-f +and +.B \-d +options to the +.B enable +builtin command +.IP \(bu +using the \fBenable\fP builtin command to enable disabled shell builtins +.IP \(bu +specifying the +.B \-p +option to the +.B command +builtin command +.IP \(bu +turning off restricted mode with +\fBset +r\fP or \fBset +o restricted\fP. +.PP +These restrictions are enforced after any startup files are read. +.PP +.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. +.\" end of rbash.1 +.if \n(zY=1 .ig zY +.SH "SEE ALSO" +.PD 0 +.TP +\fIBash Reference Manual\fP, Brian Fox and Chet Ramey +.TP +\fIThe Gnu Readline Library\fP, Brian Fox and Chet Ramey +.TP +\fIThe Gnu History Library\fP, Brian Fox and Chet Ramey +.TP +\fIPortable Operating System Interface (POSIX) Part 2: Shell and Utilities\fP, IEEE +.TP +\fIsh\fP(1), \fIksh\fP(1), \fIcsh\fP(1) +.TP +\fIemacs\fP(1), \fIvi\fP(1) +.TP +\fIreadline\fP(3) +.PD +.SH FILES +.PD 0 +.TP +.FN /bin/bash +The \fBbash\fP executable +.TP +.FN /etc/profile +The systemwide initialization file, executed for login shells +.TP +.FN ~/.bash_profile +The personal initialization file, executed for login shells +.TP +.FN ~/.bashrc +The individual per-interactive-shell startup file +.TP +.FN ~/.bash_logout +The individual login shell cleanup file, executed when a login shell exits +.TP +.FN ~/.inputrc +Individual \fIreadline\fP initialization file +.PD +.SH AUTHORS +Brian Fox, Free Software Foundation +.br +bfox@gnu.org +.PP +Chet Ramey, Case Western Reserve University +.br +chet.ramey@case.edu +.SH BUG REPORTS +If you find a bug in +.B bash, +you should report it. But first, you should +make sure that it really is a bug, and that it appears in the latest +version of +.BR bash . +The latest version is always available from +\fIftp://ftp.gnu.org/pub/gnu/bash/\fP. +.PP +Once you have determined that a bug actually exists, use the +.I 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 \fIbug-bash@gnu.org\fP or posted to the Usenet +newsgroup +.BR gnu.bash.bug . +.PP +ALL bug reports should include: +.PP +.PD 0 +.TP 20 +The version number of \fBbash\fR +.TP +The hardware and operating system +.TP +The compiler used to compile +.TP +A description of the bug behaviour +.TP +A short script or `recipe' which exercises the bug +.PD +.PP +.I bashbug +inserts the first three items automatically into the template +it provides for filing a bug report. +.PP +Comments and bug reports concerning +this manual page should be directed to +.IR chet.ramey@case.edu . +.SH BUGS +.PP +It's too big and too slow. +.PP +There are some subtle differences between +.B bash +and traditional versions of +.BR sh , +mostly because of the +.SM +.B POSIX +specification. +.PP +Aliases are confusing in some uses. +.PP +Shell builtin commands and functions are not stoppable/restartable. +.PP +Compound commands and command sequences of the form `a ; b ; c' +are not handled gracefully when process suspension is attempted. +When a process is stopped, the shell immediately executes the next +command in the sequence. +It suffices to place the sequence of commands between +parentheses to force it into a subshell, which may be stopped as +a unit. +.PP +Array variables may not (yet) be exported. +.PP +There may be only one active coprocess at a time. +.zZ +.zY diff --git a/doc/bashref.texi b/doc/bashref.texi index 77d854d65..1b144af65 100644 --- a/doc/bashref.texi +++ b/doc/bashref.texi @@ -1381,6 +1381,9 @@ Assignment statements may also appear as arguments to the @code{alias}, @code{declare}, @code{typeset}, @code{export}, @code{readonly}, and @code{local} builtin commands. +When in @sc{posix} mode (@pxref{Bash POSIX Mode}), these builtins may appear +in a command after one or more instances of the @code{command} builtin +and retain these assignment statement properties. In the context where an assignment statement is assigning a value to a shell variable or array index (@pxref{Arrays}), the @samp{+=} @@ -2965,7 +2968,8 @@ If the @option{-e} option is supplied with @option{-P} and the current working directory cannot be successfully determined after a successful directory change, @code{cd} will return an unsuccessful status. -If @var{directory} is @samp{-}, it is equivalent to @env{$OLDPWD}. +If @var{directory} is @samp{-}, it is converted to @env{$OLDPWD} +before the directory change is attempted. If a non-empty directory name from @env{CDPATH} is used, or if @samp{-} is the first argument, and the directory change is @@ -6676,6 +6680,12 @@ the normal Bash files. Tilde expansion is only performed on assignments preceding a command name, rather than on all assignment statements on the line. +@item +The @code{command} builtin does not prevent builtins that take assignment +statements as arguments from expanding them as assignment statements; +when not in POSIX mode, assignment builtins lose their assignment +statement expansion properties when preceded by @code{command}. + @item The default history file is @file{~/.sh_history} (this is the default value of @env{$HISTFILE}). diff --git a/doc/bashref.texi~ b/doc/bashref.texi~ new file mode 100644 index 000000000..5dd3ce977 --- /dev/null +++ b/doc/bashref.texi~ @@ -0,0 +1,8216 @@ +\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--2011 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 1.3 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 are free to copy and modify +this GNU manual. Buying copies from GNU Press supports the FSF in +developing GNU and promoting software freedom.'' + +@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. +* Command Line Editing:: Chapter describing the command line + editing features. +* Using History Interactively:: Command History Expansion +* 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. +* GNU Free Documentation License:: Copying and sharing this documentation. +* Indexes:: Various indexes for 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{token} that performs a control function. It is a @code{newline} +or one of the following: +@samp{||}, @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. +Operators contain at least one unquoted @code{metacharacter}. + +@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 sequence of characters treated as a unit by the shell. +Words may not include unquoted @code{metacharacters}. +@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{$'@var{string}'} are treated specially. The +word expands to @var{string}, with backslash-escaped characters replaced +as specified by the ANSI C standard. Backslash escape sequences, if +present, are decoded as follows: + +@table @code +@item \a +alert (bell) +@item \b +backspace +@item \e +@itemx \E +an escape character (not ANSI C) +@item \f +form feed +@item \n +newline +@item \r +carriage return +@item \t +horizontal tab +@item \v +vertical tab +@item \\ +backslash +@item \' +single quote +@item \" +double quote +@item \@var{nnn} +the eight-bit character whose value is the octal value @var{nnn} +(one to three digits) +@item \x@var{HH} +the eight-bit character whose value is the hexadecimal value @var{HH} +(one or two hex digits) +@item \u@var{HHHH} +the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value +@var{HHHH} (one to four hex digits) +@item \U@var{HHHHHHHH} +the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value +@var{HHHHHHHH} (one to eight hex digits) +@item \c@var{x} +a control-@var{x} character +@end table + +@noindent +The expanded result is single-quoted, as if the dollar sign had not +been present. + +@node Locale Translation +@subsubsection Locale-Specific Translation +@cindex localization +@cindex internationalization +@cindex native languages +@cindex translation, native languages + +A double-quoted string preceded by a dollar sign (@samp{$}) 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. +* Coprocesses:: Two-way communication between commands. +* GNU Parallel:: Running commands in parallel. +@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 one of +the control operators @samp{|} or @samp{|&}. + +@rwindex time +@rwindex ! +@cindex command timing +The format for a pipeline is +@example +[@code{time} [@code{-p}]] [@code{!}] @var{command1} [ [@code{|} or @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. This +connection is performed before any redirections specified by the +command. + +If @samp{|&} is used, the standard error of @var{command1} is connected to +@var{command2}'s standard input through the pipe; it is shorthand for +@code{2>&1 |}. This implicit redirection of the standard error is +performed after any redirections specified by the command. + +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}. +When the shell is in @sc{posix} mode (@pxref{Bash POSIX Mode}), +it does not recognize @code{time} as a reserved word if the next +token begins with a @samp{-}. +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. + +When the shell is in @sc{posix} mode (@pxref{Bash POSIX Mode}), @code{time} +may be followed by a newline. In this case, the shell displays the +total user and system time consumed by the shell and its children. +The @env{TIMEFORMAT} variable may be used to specify the format of +the time information. + +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. + +@sc{and} and @sc{or} lists are sequences of one or more pipelines +separated by the control operators @samp{&&} and @samp{||}, +respectively. @sc{and} and @sc{or} lists are executed with left +associativity. + +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. + +In most cases a list of commands in a compound command's description may be +separated from the rest of the command by one or more newlines, and may be +followed by a newline in place of a semicolon. + +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{commands} +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{;;}, @samp{;&}, or @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{;;}, @samp{;&}, or @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 $ANIMAL in + horse | dog | cat) echo -n "four";; + man | kangaroo ) echo -n "two";; + *) echo -n "an unknown number of";; +esac +echo " legs." +@end example + +@noindent + +If the @samp{;;} operator is used, no subsequent matches are attempted after +the first pattern match. +Using @samp{;&} in place of @samp{;;} causes execution to continue with +the @var{command-list} associated with the next clause, if any. +Using @samp{;;&} in place of @samp{;;} causes the shell to test the patterns +in the next clause, if any, and execute any associated @var{command-list} +on a successful match. + +The return status is zero if no @var{pattern} is matched. Otherwise, the +return status is the exit status of the @var{command-list} executed. + +@item select +@rwindex select + +The @code{select} construct allows the easy generation of menus. +It has almost the same syntax as the @code{for} command: + +@example +select @var{name} [in @var{words} @dots{}]; do @var{commands}; done +@end example + +The list of words following @code{in} is expanded, generating a list +of items. The set of expanded words is printed on the standard +error output stream, each preceded by a number. If the +@samp{in @var{words}} is omitted, the positional parameters are printed, +as if @samp{in "$@@"} 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 used with @samp{[[}, the @samp{<} and @samp{>} operators sort +lexicographically using the current locale. + +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 the quoted portion +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. +Any part of the pattern may be quoted to force the quoted portion +to be matched as a string. +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 or other shell metacharacters. +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 Coprocesses +@subsection Coprocesses +@cindex coprocess + +A @code{coprocess} is a shell command preceded by the @code{coproc} +reserved word. +A coprocess is executed asynchronously in a subshell, as if the command +had been terminated with the @samp{&} control operator, with a two-way pipe +established between the executing shell and the coprocess. + +The format for a coprocess is: +@example +@code{coproc} [@var{NAME}] @var{command} [@var{redirections}] +@end example + +@noindent +This creates a coprocess named @var{NAME}. +If @var{NAME} is not supplied, the default name is @var{COPROC}. +@var{NAME} must not be supplied if @var{command} is a simple +command (@pxref{Simple Commands}); otherwise, it is interpreted as +the first word of the simple command. + +When the coproc is executed, the shell creates an array variable +(@pxref{Arrays}) +named @var{NAME} in the context of the executing shell. +The standard output of @var{command} +is connected via a pipe to a file descriptor in the executing shell, +and that file descriptor is assigned to @var{NAME}[0]. +The standard input of @var{command} +is connected via a pipe to a file descriptor in the executing shell, +and that file descriptor is assigned to @var{NAME}[1]. +This pipe is established before any redirections specified by the +command (@pxref{Redirections}). +The file descriptors can be utilized as arguments to shell commands +and redirections using standard word expansions. + +The process ID of the shell spawned to execute the coprocess is +available as the value of the variable @var{NAME}_PID. +The @code{wait} +builtin command may be used to wait for the coprocess to terminate. + +The return status of a coprocess is the exit status of @var{command}. + +@node GNU Parallel +@subsection GNU Parallel + +GNU Parallel, as its name suggests, can be used to build and run commands +in parallel. You may run the same command with different arguments, whether +they are filenames, usernames, hostnames, or lines read from files. + +For a complete description, refer to the GNU Parallel documentation. A few +examples should provide a brief introduction to its use. + +For example, it is easy to prefix each line in a text file with a specified +string: +@example +cat file | parallel -k echo prefix_string +@end example +@noindent +The @option{-k} option is required to preserve the lines' order. + +Similarly, you can append a specified string to each line in a text file: +@example +cat file | parallel -k echo @{@} append_string +@end example + +You can use Parallel to move files from the current directory when the +number of files is too large to process with one @code{mv} invocation: +@example +ls | parallel mv @{@} destdir +@end example + +As you can see, the @{@} is replaced with each line read from standard input. +This will run as many @code{mv} commands as there are files in the current +directory. You can emulate a parallel @code{xargs} by adding the @option{-X} +option: +@example +ls | parallel -X mv @{@} destdir +@end example + +GNU Parallel can replace certain common idioms that operate on lines read +from a file (in this case, filenames): +@example + for x in $(cat list); do + do-something1 $x config-$x + do-something2 < $x + done | process-output +@end example + +@noindent +with a more compact syntax reminiscent of lambdas: +@example +cat list | parallel "do-something1 @{@} config-@{@} ; do-something2 < @{@}" | process-output +@end example + +Parallel provides a built-in mechanism to remove filename extensions, which +lends itself to batch file transformations or renaming: +@example +ls *.gz | parallel -j+0 "zcat @{@} | bzip2 >@{.@}.bz2 && rm @{@}" +@end example +@noindent +This will recompress all files in the current directory with names ending +in .gz using bzip2, running one job per CPU (-j+0) in parallel. + +If a command generates output, you may want to preserve the input order in +the output. For instance, the following command +@example +@{ echo foss.org.my ; echo debian.org; echo freenetproject.org; @} | parallel traceroute +@end example +@noindent +will display as output the traceroute invocation that finishes first. Using +the @option{-k} option, as we saw above +@example +@{ echo foss.org.my ; echo debian.org; echo freenetproject.org; @} | parallel -k traceroute +@end example +@noindent +will ensure that the output of @code{traceroute foss.org.my} is displayed first. + +@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 +@var{name} () @var{compound-command} [ @var{redirections} ]@*or@* +@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 from the command list +by whitespace or another shell metacharacter. +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 these exceptions: +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), +and the @env{ERR} trap is not inherited unless the @code{-o errtrace} +shell option has been enabled. +@xref{Bourne Shell Builtins}, for the description of the +@code{trap} builtin. + +The @env{FUNCNEST} variable, if set to a numeric value greater +than 0, defines a maximum function nesting level. Function +invocations that exceed the limit cause the entire command to +abort. + +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. +The @code{FUNCNEST} variable may be used to limit the depth of the +function call stack and restrict the number of function invocations. +By default, 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{"$@@"} as explained below. +Filename expansion is not performed. +Assignment statements may also appear as arguments to the +@code{alias}, +@code{declare}, @code{typeset}, @code{export}, @code{readonly}, +and @code{local} builtin commands. +When in @sc{posix} mode (@pxref{Bash POSIX Mode}), these builtins may appear +in a command after one or more instances of the @code{command} builtin +and retain these assignment statement properties. + +In the context where an assignment statement is assigning a value +to a shell variable or array index (@pxref{Arrays}), the @samp{+=} +operator can be used to +append to or add to the variable's previous value. +When @samp{+=} is applied to a variable for which the @var{integer} attribute +has been set, @var{value} is evaluated as an arithmetic expression and +added to the variable's current value, which is also evaluated. +When @samp{+=} is applied to an array variable using compound assignment +(@pxref{Arrays}), the +variable's value is not unset (as it is when using @samp{=}), and new +values are appended to the array beginning at one greater than the array's +maximum index (for indexed arrays), or added as additional key-value pairs +in an associative array. +When applied to a string-valued variable, @var{value} is expanded and +appended to the variable's value. + +@node Positional Parameters +@subsection Positional Parameters +@cindex parameters, positional + +A @var{positional parameter} is a parameter denoted by one or more +digits, other than the single digit @code{0}. Positional parameters are +assigned from the shell's arguments when it is invoked, +and may be reassigned using the @code{set} builtin command. +Positional parameter @code{N} may be referenced as @code{$@{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{"$@{@var{name}[@@]@}"} +(@pxref{Arrays}). + +After all expansions, @code{quote removal} (@pxref{Quote Removal}) +is performed. + +@node Brace Expansion +@subsection Brace Expansion +@cindex brace expansion +@cindex expansion, brace + +Brace expansion is a mechanism by which arbitrary strings may be generated. +This mechanism is similar to +@var{filename expansion} (@pxref{Filename Expansion}), +but the file names generated need not exist. +Patterns to be brace expanded take the form of an optional @var{preamble}, +followed by either a series of comma-separated strings or a sequence expression +between a pair of braces, +followed by an optional @var{postscript}. +The preamble is prefixed to each string contained within the braces, and +the postscript is then appended to each resulting string, expanding left +to right. + +Brace expansions may be nested. +The results of each expanded string are not sorted; left to right order +is preserved. +For example, +@example +bash$ echo a@{d,c,b@}e +ade ace abe +@end example + +A sequence expression takes the form @code{@{@var{x}..@var{y}[..@var{incr}]@}}, +where @var{x} and @var{y} are either integers or single characters, +and @var{incr}, an optional increment, is an integer. +When integers are supplied, the expression expands to each number between +@var{x} and @var{y}, inclusive. +Supplied integers may be prefixed with @samp{0} to force each term to have the +same width. When either @var{x} or @var{y} begins with a zero, the shell +attempts to force all generated terms to contain the same number of digits, +zero-padding where necessary. +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. +When the increment is supplied, it is used as the difference between +each term. The default increment is 1 or -1 as appropriate. + +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, using the form described +below, 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 @var{parameter}'s existence and that its 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 $@{@var{parameter}:@var{offset}:@var{length}@} +Expands to up to @var{length} characters of @var{parameter} +starting at the character specified by @var{offset}. +If @var{length} is omitted, expands to the substring of +@var{parameter} starting at the character specified by @var{offset}. +@var{length} and @var{offset} are arithmetic expressions +(@pxref{Shell Arithmetic}). +This is referred to as Substring Expansion. + +If @var{offset} evaluates to a number less than zero, the value +is used as an offset from the end of the value of @var{parameter}. +If @var{length} evaluates to a number less than zero, and @var{parameter} +is not @samp{@@} and not an indexed or associative array, it is interpreted +as an offset from the end of the value of @var{parameter} rather than +a number of characters, and the expansion is the characters between the +two offsets. +If @var{parameter} is @samp{@@}, the result is @var{length} positional +parameters beginning at @var{offset}. +If @var{parameter} is an indexed array name subscripted +by @samp{@@} or @samp{*}, the result is the @var{length} +members of the array beginning with @code{$@{@var{parameter}[@var{offset}]@}}. +A negative @var{offset} is taken relative to one greater than the maximum +index of the specified array. +Substring expansion applied to an associative array produces undefined +results. + +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. + +@item $@{@var{parameter}^@var{pattern}@} +@itemx $@{@var{parameter}^^@var{pattern}@} +@itemx $@{@var{parameter},@var{pattern}@} +@itemx $@{@var{parameter},,@var{pattern}@} +This expansion modifies the case of alphabetic characters in @var{parameter}. +The @var{pattern} is expanded to produce a pattern just as in +filename expansion. +The @samp{^} operator converts lowercase letters matching @var{pattern} +to uppercase; the @samp{,} operator converts matching uppercase letters +to lowercase. +The @samp{^^} and @samp{,,} expansions convert each matched character in the +expanded value; the @samp{^} and @samp{,} expansions match and convert only +the first character in the expanded value. +If @var{pattern} is omitted, it is treated like a @samp{?}, which matches +every character. +If @var{parameter} is @samp{@@} or @samp{*}, +the case modification operation is applied to each positional +parameter in turn, and the expansion is the resultant list. +If @var{parameter} +is an array variable subscripted with @samp{@@} or @samp{*}, +the case modification operation is applied to each member of the +array in turn, and the expansion is the resultant list. + +@end table + +@node Command Substitution +@subsection Command Substitution +@cindex command substitution + +Command substitution allows the output of a command to replace +the command itself. +Command substitution occurs when a command is enclosed as follows: +@example +$(@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 (@pxref{Pattern Matching}). +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 expansion, 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. +When the @code{globstar} shell option is enabled, and @samp{*} is used in +a filename expansion context, two adjacent @samp{*}s used as a single +pattern will match all files and zero or more directories and +subdirectories. +If followed by a @samp{/}, two adjacent @samp{*}s will match only +directories and subdirectories. +@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 values of the +@env{LC_COLLATE} and @env{LC_ALL} shell variables, 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}, or enable the +@code{globasciiranges} shell option. + +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. + +Each redirection that may be preceded by a file descriptor number +may instead be preceded by a word of the form @{@var{varname}@}. +In this case, for each redirection operator except +>&- and <&-, the shell will allocate a file descriptor greater +than 10 and assign it to @{@var{varname}@}. If >&- or <&- is preceded +by @{@var{varname}@}, the value of @var{varname} defines the file +descriptor to close. + +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 made a copy of the 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 +This construct 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}. + +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 +(see Duplicating File Descriptors below). + +@subsection Appending Standard Output and Standard Error +This construct allows both the +standard output (file descriptor 1) and +the standard error output (file descriptor 2) +to be appended to the file whose name is the +expansion of @var{word}. + +The format for appending standard output and standard error is: +@example +&>>@var{word} +@end example +@noindent +This is semantically equivalent to +@example +>>@var{word} 2>&1 +@end example +(see Duplicating File Descriptors below). + +@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 as described above, with the exception that +pathname expansion is not applied, and supplied as a single string +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 searches for a defined shell +function named @code{command_not_found_handle}. +If that function exists, it is invoked with the original command and +the original command's arguments as its arguments, and the function's +exit status becomes the exit status of the shell. +If that function is not defined, 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. + +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. + +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 + +The exit status of an executed command is the value returned by the +@var{waitpid} system call or equivalent function. Exit statuses +fall between 0 and 255, though, as explained below, the shell may +use values above 125 specially. Exit statuses from shell builtins and +compound commands are also limited to this range. Under certain +circumstances, the shell will use special values to indicate specific +failure modes. + +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. +The @code{:}, @code{true}, @code{false}, and @code{test} +builtins do not accept options and do not treat @samp{--} specially. +The @code{exit}, @code{logout}, @code{break}, @code{continue}, @code{let}, +and @code{shift} builtins accept and process arguments beginning +with @samp{-} without requiring @samp{--}. +Other builtins that accept arguments but are not specified as accepting +options interpret arguments beginning with @samp{-} as invalid options and +require @samp{--} to prevent this interpretation. + +@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 [-e]]] [@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 the @option{-e} option is supplied with @option{-P} +and the current working directory cannot be successfully determined +after a successful directory change, @code{cd} will return an unsuccessful +status. +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 @var{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 +Each time @code{hash} is invoked, it remembers the full pathnames of the +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}. +Any previously-remembered pathname is discarded. +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 [-aAf] [-p] [@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 indexed +array variable; the @option{-A} option means each @var{name} refers +to an associative array variable. +If both options are supplied, @option{-A} takes precedence. +If no @var{name} arguments are given, or if the @option{-p} +option is supplied, a list of all readonly names is printed. +The other options may be used to restrict the output to a subset of +the set of readonly names. +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. +The evaluation depends on the number of arguments; see below. +Operator precedence is used when there are five or more arguments. + +@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 +The following conditions are applied in the order listed. +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. +The @samp{-a} and @samp{-o} operators are considered binary operators +when there are three arguments. +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. + +@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 + +When used with @code{test} or @samp{[}, the @samp{<} and @samp{>} +operators sort lexicographically using ASCII ordering. + +@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{extdebug} 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{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. + +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 following the @code{if} or @code{elif} reserved words, +part of a command executed in 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. + +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 subshell or subshell environment when one 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 the @option{-v} option is given, each +@var{name} refers to a shell variable and that variable is remvoved. +If the @option{-f} option is given, the @var{name}s refer to shell +functions, and the function definition is removed. +If no options are supplied, each @var{name} refers to a variable; if +there is no variable by that name, any function with that name is +unset. +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. +When @var{shell-command} is executed, the shell sets the +@code{READLINE_LINE} variable to the contents of the Readline line +buffer and the @code{READLINE_POINT} variable to the current location +of the insertion point. +If the executed command changes the value of @code{READLINE_LINE} or +@code{READLINE_POINT}, those new values will be reflected in the +editing state. +@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 [-aAfFilrtux] [-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 with @var{name} arguments, additional options +are ignored. + +When @option{-p} is supplied without @var{name} arguments, @code{declare} +will display the attributes and values of all variables having the +attributes specified by the additional options. +If no other options are supplied with @option{-p}, @code{declare} will +display the attributes and values of all shell variables. The @option{-f} +option will restrict the display to shell functions. + +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 @option{-g} option forces variables to be created or modified at +the global scope, even when @code{declare} is executed in a shell function. +It is ignored in all other cases. + +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 indexed array variable (@pxref{Arrays}). + +@item -A +Each @var{name} is an associative 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 -l +When the variable is assigned a value, all upper-case characters are +converted to lower-case. +The upper-case attribute is disabled. + +@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 -u +When the variable is assigned a value, all lower-case characters are +converted to upper-case. +The lower-case attribute is disabled. + +@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, unless the @samp{-g} option is used. +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 0 unless a write error occurs. +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 further output +@item \e +@itemx \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) +@item \u@var{HHHH} +the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value +@var{HHHH} (one to four hex digits) +@item \U@var{HHHHHHHH} +the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value +@var{HHHHHHHH} (one to eight 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 [-dms] [@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. + +Options, if supplied, have the following meanings: + +@table @code +@item -d +Display a short description of each @var{pattern} +@item -m +Display the description of each @var{pattern} in a manpage-like format +@item -s +Display only a short usage synopsis for each @var{pattern} +@end table + +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 mapfile +@btindex mapfile +@example +mapfile [-n @var{count}] [-O @var{origin}] [-s @var{count}] [-t] [-u @var{fd}] [ +-C @var{callback}] [-c @var{quantum}] [@var{array}] +@end example +Read lines from the standard input into the indexed array variable @var{array}, +or from file descriptor @var{fd} +if the @option{-u} option is supplied. +The variable @code{MAPFILE} is the default @var{array}. +Options, if supplied, have the following meanings: +@table @code + +@item -n +Copy at most @var{count} lines. If @var{count} is 0, all lines are copied. +@item -O +Begin assigning to @var{array} at index @var{origin}. +The default index is 0. +@item -s +Discard the first @var{count} lines read. +@item -t +Remove a trailing newline from each line read. +@item -u +Read lines from file descriptor @var{fd} instead of the standard input. +@item -C +Evaluate @var{callback} each time @var{quantum}P lines are read. +The @option{-c} option specifies @var{quantum}. +@item -c +Specify the number of lines read between each call to @var{callback}. +@end table + +If @option{-C} is specified without @option{-c}, +the default quantum is 5000. +When @var{callback} is evaluated, it is supplied the index of the next +array element to be assigned and the line to be assigned to that element +as additional arguments. +@var{callback} is evaluated after the line is read but before the +array element is assigned. + +If not supplied with an explicit origin, @code{mapfile} will clear @var{array} +before assigning to it. + +@code{mapfile} returns successfully unless an invalid option or option +argument is supplied, @var{array} is invalid or unassignable, or @var{array} +is not an indexed array. + +@item printf +@btindex printf +@example +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 @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 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, @code{printf} +interprets the following extensions: + +@table @code +@item %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). +@item %q +causes @code{printf} to output the +corresponding @var{argument} in a format that can be reused as shell input. +@item %(@var{datefmt})T +causes @code{printf} to output the date-time string resulting from using +@var{datefmt} as a format string for @code{strftime}(3). The corresponding +@var{argument} is an integer representing the number of seconds since the +epoch. Two special argument values may be used: -1 represents the current +time, and -2 represents the time the shell was invoked. +@end table + +@noindent +Arguments to non-string format specifiers are treated as C language constants, +except that a leading plus or minus sign is allowed, and if the leading +character is a single or double quote, the value is the ASCII value of +the following character. + +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}] [-i @var{text}] [-n @var{nchars}] [-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 (in which case the return code is greater than 128), 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. +Readline uses the current (or default, if line editing was not previously +active) editing settings. + +@item -i @var{text} +If Readline is being used to read the line, @var{text} is placed into +the editing buffer before editing begins. + +@item -n @var{nchars} +@code{read} returns after reading @var{nchars} characters rather than +waiting for a complete line of input, but honor a delimiter if fewer +than @var{nchars} characters are read before the delimiter. + +@item -N @var{nchars} +@code{read} returns after reading exactly @var{nchars} characters rather +than waiting for a complete line of input, unless EOF is encountered or +@code{read} times out. +Delimiter characters encountered in the input are +not treated specially and do not cause @code{read} to return until +@var{nchars} characters are read. + +@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. +@var{timeout} may be a decimal number with a fractional portion following +the decimal point. +This option is only effective if @code{read} is reading input from a +terminal, pipe, or other special file; it has no effect when reading +from regular files. +If @var{timeout} is 0, @code{read} returns success if input is available on +the specified file descriptor, failure otherwise. +The exit status is greater than 128 if the timeout is exceeded. + +@item -u @var{fd} +Read input from file descriptor @var{fd}. + +@end table + +@item readarray +@btindex readarray +@example +readarray [-n @var{count}] [-O @var{origin}] [-s @var{count}] [-t] [-u @var{fd}] [ +-C @var{callback}] [-c @var{quantum}] [@var{array}] +@end example +Read lines from the standard input into the indexed array variable @var{array}, +or from file descriptor @var{fd} +if the @option{-u} option is supplied. + +A synonym for @code{mapfile}. + +@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 all of the @var{names} are found, non-zero +if any are not 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 [-abcdefilmnpqrstuvxHST] [@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 -b +The maximum socket buffer size. + +@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 (many systems do not honor this limit). + +@item -n +The maximum number of open file descriptors (most systems do not +allow this value to be set). + +@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 shell, and, on +some systems, to its children. + +@item -x +The maximum number of file locks. + +@item -T +The maximum number of threads. + +@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. +A hard limit cannot be increased by a non-root user once it is set; +a soft limit may be increased up to the value of the hard limit. +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-name}] [@var{argument} @dots{}] +set [+abefhkmnptuvxBCEHPT] [+o @var{option-name}] [@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 pipeline (@pxref{Pipelines}), which may consist +of a single simple command (@pxref{Simple Commands}), +a subshell command enclosed in parentheses (@pxref{Command Grouping}), +or one of the commands executed as part of a command list enclosed +by braces (@pxref{Command Grouping}) +returns a non-zero status. +The shell does not exit if 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 any command executed in a @code{&&} or @code{||} list except +the command following the final @code{&&} or @code{||}, +any command in a pipeline but the last, +or if the command's return status is being inverted with @code{!}. +A trap on @code{ERR}, if set, is executed before the shell exits. + +This option applies to the shell environment and each subshell environment +separately (@pxref{Command Execution Environment}), and may cause +subshells to exit before executing all the commands in the subshell. + +@item -f +Disable filename expansion (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}). +All processes run in a separate process group. +When a background job completes, the shell prints a line +containing its exit status. + +@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}). +This also affects the editing interface used for @code{read -e}. + +@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. +This also affects the editing interface used for @code{read -e}. + +@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}, @env{BASHOPTS}, @env{CDPATH} and @env{GLOBIGNORE} +variables, if they appear in the environment, are 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 and parameters other than the special parameters +@samp{@@} or @samp{*} 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 compat31 +If set, Bash +changes its behavior to that of version 3.1 with respect to quoted +arguments to the conditional command's @samp{=~} operator. + +@item compat32 +If set, Bash +changes its behavior to that of version 3.2 with respect to locale-specific +string comparison when using the @samp{[[} +conditional command's @samp{<} and @samp{>} operators. +Bash versions prior to bash-4.0 use ASCII collation and strcmp(3); +bash-4.1 and later use the current locale's collation sequence and strcoll(3). + +@item compat40 +If set, Bash +changes its behavior to that of version 4.0 with respect to locale-specific +string comparison when using the @samp{[[} +conditional command's @samp{<} and @samp{>} operators (see previous item) +and the effect of interrupting a command list. + +@item compat41 +If set, Bash, when in posix mode, treats a single quote in a double-quoted +parameter expansion as a special character. The single quotes must match +(an even number) and the characters between the single quotes are considered +quoted. This is the behavior of @sc{posix} mode through version 4.1. +The default Bash behavior remains as in previous versions. + +@item direxpand +If set, Bash +replaces directory names with the results of word expansion when performing +filename completion. This changes the contents of the readline editing +buffer. +If not set, Bash attempts to preserve what the user typed. + +@item dirspell +If set, Bash +attempts spelling correction on directory names during word completion +if the directory name initially supplied does not exist. + +@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{ERR} 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 filename 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 globasciiranges +If set, range expressions used in pattern matching (@pxref{Pattern Matching}) +behave as if in the traditional C locale when performing +comparisons. That is, the current locale's collating sequence +is not taken into account, so +@samp{b} will not collate between @samp{A} and @samp{B}, +and upper-case and lower-case ASCII characters will collate together. + +@item globstar +If set, the pattern @samp{**} used in a filename expansion context will +match all files and zero or more directories and subdirectories. +If the pattern is followed by a @samp{/}, only directories and +subdirectories match. + +@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 lastpipe +If set, and job control is not active, the shell runs the last command of +a pipeline not executed in the background in the current shell environment. + +@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 or directory name +and the @env{MAILPATH} variable +is not set, Bash informs the user of the arrival of mail in +the specified file or Maildir-format directory. + +@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 BASHOPTS +A colon-separated list of enabled shell options. Each word in +the list is a valid argument for the @option{-s} option to the +@code{shopt} builtin command (@pxref{The Shopt Builtin}). +The options appearing in @env{BASHOPTS} are those reported +as @samp{on} by @samp{shopt}. +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 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_ALIASES +An associative array variable whose members correspond to the internal +list of aliases as maintained by the @code{alias} builtin. +(@pxref{Bourne Shell Builtins}). +Elements added to this array appear in the alias list; unsetting array +elements cause aliases to be removed from the alias list. + +@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_CMDS +An associative array variable whose members correspond to the internal +hash table of commands as maintained by the @code{hash} builtin +(@pxref{Bourne Shell Builtins}). +Elements added to this array appear in the hash table; unsetting array +elements cause commands to be removed from the hash table. + +@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 +where each corresponding member of @var{FUNCNAME} was invoked. +@code{$@{BASH_LINENO[$i]@}} is the line number in the source file +(@code{$@{BASH_SOURCE[$i+1]@}}) where +@code{$@{FUNCNAME[$i]@}} was called (or @code{$@{BASH_LINENO[$i-1]@}} if +referenced within another shell function). +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 where the +corresponding shell function names in the @code{FUNCNAME} array +variable are defined. +The shell function @code{$@{FUNCNAME[$i]@}} is defined in the file +@code{$@{BASH_SOURCE[$i]@}} and called from @code{$@{BASH_SOURCE[$i+1]@}} + +@item BASH_SUBSHELL +Incremented by one within each subshell or subshell environment when +the shell begins executing in that environment. +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 BASH_XTRACEFD +If set to an integer corresponding to a valid file descriptor, Bash +will write the trace output generated when @samp{set -x} +is enabled to that file descriptor. +This allows tracing output to be separated from diagnostic and error +messages. +The file descriptor is closed when @code{BASH_XTRACEFD} is unset or assigned +a new value. +Unsetting @code{BASH_XTRACEFD} or assigning it the empty string causes the +trace output to be sent to the standard error. +Note that setting @code{BASH_XTRACEFD} to 2 (the standard error file +descriptor) and then unsetting it will result in the standard error +being closed. + +@item COLUMNS +Used by the @code{select} command to determine the terminal width +when printing selection lists. Automatically set by an interactive shell +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 line is split into words as Readline would split it, using +@code{COMP_WORDBREAKS} as described above. +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 COPROC +An array variable created to hold the file descriptors +for output from and input to an unnamed coprocess (@pxref{Coprocesses}). + +@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 ENV +Similar to @code{BASH_ENV}; used when the shell is invoked in +@sc{posix} Mode (@pxref{Bash POSIX Mode}). + +@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 (the one with the highest index) +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. + +This variable can be used with @code{BASH_LINENO} and @code{BASH_SOURCE}. +Each element of @code{FUNCNAME} has corresponding elements in +@code{BASH_LINENO} and @code{BASH_SOURCE} to describe the call stack. +For instance, @code{$@{FUNCNAME[$i]@}} was called from the file +@code{$@{BASH_SOURCE[$i+1]@}} at line number @code{$@{BASH_LINENO[$i]@}}. +The @code{caller} builtin displays the current call stack using this +information. + +@item FUNCNEST +If set to a numeric value greater than 0, defines a maximum function +nesting level. Function invocations that exceed this nesting level +will cause the current command to abort. + +@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. +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 +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, or does not name a readable file, +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} command to determine the column length +for printing selection lists. Automatically set by an interactive shell +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 MAPFILE +An array variable created to hold the text read by the +@code{mapfile} builtin when no variable name is supplied. + +@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 PROMPT_DIRTRIM +If set to a number greater than zero, the value is used as the number of +trailing directory components to retain when expanding the @code{\w} and +@code{\W} prompt string escapes (@pxref{Printing a Prompt}). +Characters removed are replaced with an ellipsis. + +@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 READLINE_LINE +The contents of the Readline line buffer, for use +with @samp{bind -x} (@pxref{Bash Builtins}). + +@item READLINE_POINT +The position of the insertion point in the Readline line buffer, for use +with @samp{bind -x} (@pxref{Bash Builtins}). + +@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 + +All of the single-character options used with the @code{set} builtin +(@pxref{The Set Builtin}) can be used as options when the shell is invoked. +In addition, 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). + +@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 with its standard input +connected to a network connection, as when executed by the remote shell +daemon, usually @code{rshd}, or the secure shell daemon @code{sshd}. +If Bash determines it is being run in +this fashion, 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}, @env{BASHOPTS}, @env{CDPATH}, and @env{GLOBIGNORE} +variables, if they appear in the environment, are 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. + +When used with @samp{[[}, the @samp{<} and @samp{>} operators sort +lexicographically using the current locale. +The @code{test} command uses ASCII ordering. + +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 -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 -N @var{file} +True if @var{file} exists and has been modified since it was last read. + +@item -O @var{file} +True if @var{file} exists and is owned by the effective user id. + +@item -S @var{file} +True if @var{file} exists and is a socket. + +@item @var{file1} -ef @var{file2} +True if @var{file1} and @var{file2} refer to the same device and +inode numbers. + +@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 -o @var{optname} +True if the 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 -v @var{varname} +True if the shell variable @var{varname} is set (has been assigned a value). + +@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} +@itemx @var{string1} = @var{string2} +True if the strings are equal. +@samp{=} should be used with the @code{test} command for @sc{posix} conformance. + +@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. + +@item @var{string1} > @var{string2} +True if @var{string1} sorts after @var{string2} lexicographically. + +@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 @var{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 the optional @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 indexed and associative array variables. +Any variable may be used as an indexed 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. +Indexed arrays are referenced using integers (including arithmetic +expressions (@pxref{Shell Arithmetic})) and are zero-based; +associative arrays use arbitrary strings. + +An indexed 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. +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. + +Associative arrays are created using +@example +declare -A @var{name}. +@end example + +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}. +Indexed array assignments do not require the bracket and subscript. +When assigning to indexed arrays, 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. + +When assigning to an associative array, the subscript is required. + +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 with a subscript of 0. +If the @var{subscript} +used to reference an element of an indexed array +evaluates to a number less than zero, it is used as +an offset from one greater than the array's maximum index (so a subcript +of -1 refers to the last element of the array). + +An array variable is considered set if a subscript has been assigned a +value. The null string is a valid value. + +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 +expansion. +@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 indexed +array and a @option{-A} option to specify an associative array. +If both options are supplied, @option{-A} takes precedence. +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 +(uses the @env{$PROMPT_DIRTRIM} variable). +@item \W +The basename of @env{$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 @code{command} builtin does not prevent builtins that take assignment +statements as arguments from expanding them as assignment statements; +when not in POSIX mode, assignment builtins lose their assignment +statement expansion properties when preceded by @code{command}. + +@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 +Non-interactive shells exit if there is a syntax error in a script read +with the @code{.} or @code{source} builtins, or in a string processed by +the @code{eval} builtin. + +@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 +The @code{time} reserved word may be used by itself as a command. When +used in this way, it displays timing statistics for the shell and its +completed children. The @env{TIMEFORMAT} variable controls the format +of the timing information. + +@item +When parsing and expanding a $@{@dots{}@} expansion that appears within +double quotes, single quotes are no longer special and cannot be used to +quote a closing brace or other special character, unless the operator is +one of those defined to perform pattern removal. In this case, they do +not have to appear as matched pairs. + +@item +The parser does not recognize @code{time} as a reserved word if the next +token begins with a @samp{-}. + +@item +If a @sc{posix} special builtin returns an error status, a +non-interactive shell exits. The fatal errors are those listed in +the @sc{posix} standard, and include things like passing incorrect options, +redirection errors, variable assignment errors for assignments preceding +the command name, and so on. + +@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 exists with an error status if a variable +assignment error occurs in an assignment statement preceding a special +builtin, but not with any other simple command. + +@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 +While variable indirection is available, it may not be applied to the +@samp{#} and @samp{?} special parameters. + +@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 +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{$PATH}. + +@item +The @code{vi} editing mode will invoke the @code{vi} editor directly when +the @samp{v} command is run, instead of checking @code{$VISUAL} and +@code{$EDITOR}. + +@item +When the @code{xpg_echo} option is enabled, Bash does not attempt to interpret +any arguments to @code{echo} as options. Each argument is displayed, after +escape characters are converted. + +@item +The @code{ulimit} builtin uses a block size of 512 bytes for the @option{-c} +and @option{-f} options. + +@item +The arrival of @code{SIGCHLD} when a trap is set on @code{SIGCHLD} does +not interrupt the @code{wait} builtin and cause it to return immediately. +The trap command is run once for each child that exits. + +@end enumerate + +There is other @sc{posix} behavior that Bash does not implement by +default even when in @sc{posix} mode. +Specifically: + +@enumerate + +@item +The @code{fc} builtin checks @code{$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 operating system kernel'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, if +the user so specifies with @code{stty tostop}, write to the terminal. +Background processes which attempt to +read from (write to when @code{stty tostop} is in effect) the +terminal are sent a @code{SIGTTIN} (@code{SIGTTOU}) +signal by the kernel's 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 specification (@var{jobspec}). + +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{%-}. +If there is only a single job, @samp{%+} and @samp{%-} can both be used +to refer to that job. +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. +A login shell cannot be suspended; the @option{-f} +option can be used to override this and force the suspension. + +@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-casemod-attributes +Include support for case-modifying attributes in the @code{declare} builtin +and assignment statements. Variables with the @var{uppercase} attribute, +for example, will have their values converted to uppercase upon assignment. + +@item --enable-casemod-expansion +Include support for case-modifying word expansions. + +@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 @sc{posix} regular expressions using the +@samp{=~} binary operator in the @code{[[} conditional command. +(@pxref{Conditional Constructs}). + +@item --enable-coprocesses +Include support for coprocesses and the @code{coproc} reserved word +(@pxref{Pipelines}). + +@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-extended-glob-default +Set the default value of the @var{extglob} shell option described +above under @ref{The Shopt Builtin} to be enabled. + +@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} compound command, 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/gnu/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.ramey@@case.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 builtin commands +@code{complete}, @code{compgen}, and @code{compopt}, 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 GNU Free Documentation License +@appendix GNU Free Documentation License + +@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 +@appendixsec Index of Shell Builtin Commands +@printindex bt + +@node Reserved Word Index +@appendixsec Index of Shell Reserved Words +@printindex rw + +@node Variable Index +@appendixsec Parameter and Variable Index +@printindex vr + +@node Function Index +@appendixsec Function Index +@printindex fn + +@node Concept Index +@appendixsec Concept Index +@printindex cp + +@bye diff --git a/doc/version.texi b/doc/version.texi index b6e5604fb..69b849ef6 100644 --- a/doc/version.texi +++ b/doc/version.texi @@ -2,9 +2,9 @@ Copyright (C) 1988-2011 Free Software Foundation, Inc. @end ignore -@set LASTCHANGE Thu Jul 7 07:34:57 EDT 2011 +@set LASTCHANGE Thu Jul 28 18:11:38 EDT 2011 @set EDITION 4.2 @set VERSION 4.2 -@set UPDATED 7 July 2011 +@set UPDATED 28 July 2011 @set UPDATED-MONTH July 2011 diff --git a/doc/version.texi~ b/doc/version.texi~ new file mode 100644 index 000000000..3cdb3b5ef --- /dev/null +++ b/doc/version.texi~ @@ -0,0 +1,10 @@ +@ignore +Copyright (C) 1988-2011 Free Software Foundation, Inc. +@end ignore + +@set LASTCHANGE Sun Jul 24 16:17:58 EDT 2011 + +@set EDITION 4.2 +@set VERSION 4.2 +@set UPDATED 24 July 2011 +@set UPDATED-MONTH July 2011 diff --git a/execute_cmd.c b/execute_cmd.c index 9007dff91..16a2f9a98 100644 --- a/execute_cmd.c +++ b/execute_cmd.c @@ -3652,7 +3652,7 @@ static void fix_assignment_words (words) WORD_LIST *words; { - WORD_LIST *w; + WORD_LIST *w, *wcmd; struct builtin *b; int assoc; @@ -3662,16 +3662,24 @@ fix_assignment_words (words) b = 0; assoc = 0; + wcmd = words; for (w = words; w; w = w->next) if (w->word->flags & W_ASSIGNMENT) { if (b == 0) { - b = builtin_address_internal (words->word->word, 0); + /* Posix (post-2008) says that `command' doesn't change whether + or not the builtin it shadows is a `declaration command', even + though it removes other special builtin properties. In Posix + mode, we skip over one or more instances of `command' and + deal with the next word as the assignment builtin. */ + while (posixly_correct && wcmd && wcmd->word && wcmd->word->word && STREQ (wcmd->word->word, "command")) + wcmd = wcmd->next; + b = builtin_address_internal (wcmd->word->word, 0); if (b == 0 || (b->flags & ASSIGNMENT_BUILTIN) == 0) return; else if (b && (b->flags & ASSIGNMENT_BUILTIN)) - words->word->flags |= W_ASSNBLTIN; + wcmd->word->flags |= W_ASSNBLTIN; } w->word->flags |= (W_NOSPLIT|W_NOGLOB|W_TILDEEXP|W_ASSIGNARG); #if defined (ARRAY_VARS) @@ -3686,13 +3694,15 @@ fix_assignment_words (words) { if (b == 0) { - b = builtin_address_internal (words->word->word, 0); + while (posixly_correct && wcmd && wcmd->word && wcmd->word->word && STREQ (wcmd->word->word, "command")) + wcmd = wcmd->next; + b = builtin_address_internal (wcmd->word->word, 0); if (b == 0 || (b->flags & ASSIGNMENT_BUILTIN) == 0) return; else if (b && (b->flags & ASSIGNMENT_BUILTIN)) - words->word->flags |= W_ASSNBLTIN; + wcmd->word->flags |= W_ASSNBLTIN; } - if (words->word->flags & W_ASSNBLTIN) + if (wcmd->word->flags & W_ASSNBLTIN) assoc = 1; } #endif diff --git a/execute_cmd.c~ b/execute_cmd.c~ new file mode 100644 index 000000000..1fef517b0 --- /dev/null +++ b/execute_cmd.c~ @@ -0,0 +1,5263 @@ +/* execute_cmd.c -- Execute a COMMAND structure. */ + +/* Copyright (C) 1987-2010 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 3 of the License, 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. If not, see . +*/ + +#include "config.h" + +#if !defined (__GNUC__) && !defined (HAVE_ALLOCA_H) && defined (_AIX) + #pragma alloca +#endif /* _AIX && RISC6000 && !__GNUC__ */ + +#include +#include "chartypes.h" +#include "bashtypes.h" +#if !defined (_MINIX) && defined (HAVE_SYS_FILE_H) +# include +#endif +#include "filecntl.h" +#include "posixstat.h" +#include +#ifndef _MINIX +# include +#endif + +#if defined (HAVE_UNISTD_H) +# include +#endif + +#include "posixtime.h" + +#if defined (HAVE_SYS_RESOURCE_H) && !defined (RLIMTYPE) +# include +#endif + +#if defined (HAVE_SYS_TIMES_H) && defined (HAVE_TIMES) +# include +#endif + +#include + +#if !defined (errno) +extern int errno; +#endif + +#define NEED_FPURGE_DECL + +#include "bashansi.h" +#include "bashintl.h" + +#include "memalloc.h" +#include "shell.h" +#include /* use <...> so we pick it up from the build directory */ +#include "flags.h" +#include "builtins.h" +#include "hashlib.h" +#include "jobs.h" +#include "execute_cmd.h" +#include "findcmd.h" +#include "redir.h" +#include "trap.h" +#include "pathexp.h" +#include "hashcmd.h" + +#if defined (COND_COMMAND) +# include "test.h" +#endif + +#include "builtins/common.h" +#include "builtins/builtext.h" /* list of builtins */ + +#include +#include + +#if defined (BUFFERED_INPUT) +# include "input.h" +#endif + +#if defined (ALIAS) +# include "alias.h" +#endif + +#if defined (HISTORY) +# include "bashhist.h" +#endif + +extern int dollar_dollar_pid; +extern int posixly_correct; +extern int expand_aliases; +extern int autocd; +extern int breaking, continuing, loop_level; +extern int parse_and_execute_level, running_trap, sourcelevel; +extern int command_string_index, line_number; +extern int dot_found_in_search; +extern int already_making_children; +extern int tempenv_assign_error; +extern char *the_printed_command, *shell_name; +extern pid_t last_command_subst_pid; +extern sh_builtin_func_t *last_shell_builtin, *this_shell_builtin; +extern char **subshell_argv, **subshell_envp; +extern int subshell_argc; +extern time_t shell_start_time; +#if 0 +extern char *glob_argv_flags; +#endif + +extern int close __P((int)); + +/* Static functions defined and used in this file. */ +static void close_pipes __P((int, int)); +static void do_piping __P((int, int)); +static void bind_lastarg __P((char *)); +static int shell_control_structure __P((enum command_type)); +static void cleanup_redirects __P((REDIRECT *)); + +#if defined (JOB_CONTROL) +static int restore_signal_mask __P((sigset_t *)); +#endif + +static void async_redirect_stdin __P((void)); + +static int builtin_status __P((int)); + +static int execute_for_command __P((FOR_COM *)); +#if defined (SELECT_COMMAND) +static int displen __P((const char *)); +static int print_index_and_element __P((int, int, WORD_LIST *)); +static void indent __P((int, int)); +static void print_select_list __P((WORD_LIST *, int, int, int)); +static char *select_query __P((WORD_LIST *, int, char *, int)); +static int execute_select_command __P((SELECT_COM *)); +#endif +#if defined (DPAREN_ARITHMETIC) +static int execute_arith_command __P((ARITH_COM *)); +#endif +#if defined (COND_COMMAND) +static int execute_cond_node __P((COND_COM *)); +static int execute_cond_command __P((COND_COM *)); +#endif +#if defined (COMMAND_TIMING) +static int mkfmt __P((char *, int, int, time_t, int)); +static void print_formatted_time __P((FILE *, char *, + time_t, int, time_t, int, + time_t, int, int)); +static int time_command __P((COMMAND *, int, int, int, struct fd_bitmap *)); +#endif +#if defined (ARITH_FOR_COMMAND) +static intmax_t eval_arith_for_expr __P((WORD_LIST *, int *)); +static int execute_arith_for_command __P((ARITH_FOR_COM *)); +#endif +static int execute_case_command __P((CASE_COM *)); +static int execute_while_command __P((WHILE_COM *)); +static int execute_until_command __P((WHILE_COM *)); +static int execute_while_or_until __P((WHILE_COM *, int)); +static int execute_if_command __P((IF_COM *)); +static int execute_null_command __P((REDIRECT *, int, int, int)); +static void fix_assignment_words __P((WORD_LIST *)); +static int execute_simple_command __P((SIMPLE_COM *, int, int, int, struct fd_bitmap *)); +static int execute_builtin __P((sh_builtin_func_t *, WORD_LIST *, int, int)); +static int execute_function __P((SHELL_VAR *, WORD_LIST *, int, struct fd_bitmap *, int, int)); +static int execute_builtin_or_function __P((WORD_LIST *, sh_builtin_func_t *, + SHELL_VAR *, + REDIRECT *, struct fd_bitmap *, int)); +static void execute_subshell_builtin_or_function __P((WORD_LIST *, REDIRECT *, + sh_builtin_func_t *, + SHELL_VAR *, + int, int, int, + struct fd_bitmap *, + int)); +static int execute_disk_command __P((WORD_LIST *, REDIRECT *, char *, + int, int, int, struct fd_bitmap *, int)); + +static char *getinterp __P((char *, int, int *)); +static void initialize_subshell __P((void)); +static int execute_in_subshell __P((COMMAND *, int, int, int, struct fd_bitmap *)); +#if defined (COPROCESS_SUPPORT) +static int execute_coproc __P((COMMAND *, int, int, struct fd_bitmap *)); +#endif + +static int execute_pipeline __P((COMMAND *, int, int, int, struct fd_bitmap *)); + +static int execute_connection __P((COMMAND *, int, int, int, struct fd_bitmap *)); + +static int execute_intern_function __P((WORD_DESC *, COMMAND *)); + +/* Set to 1 if fd 0 was the subject of redirection to a subshell. Global + so that reader_loop can set it to zero before executing a command. */ +int stdin_redir; + +/* The name of the command that is currently being executed. + `test' needs this, for example. */ +char *this_command_name; + +/* The printed representation of the currently-executing command (same as + the_printed_command), except when a trap is being executed. Useful for + a debugger to know where exactly the program is currently executing. */ +char *the_printed_command_except_trap; + +/* For catching RETURN in a function. */ +int return_catch_flag; +int return_catch_value; +procenv_t return_catch; + +/* The value returned by the last synchronous command. */ +int last_command_exit_value; + +/* Whether or not the last command (corresponding to last_command_exit_value) + was terminated by a signal, and, if so, which one. */ +int last_command_exit_signal; + +/* The list of redirections to perform which will undo the redirections + that I made in the shell. */ +REDIRECT *redirection_undo_list = (REDIRECT *)NULL; + +/* The list of redirections to perform which will undo the internal + redirections performed by the `exec' builtin. These are redirections + that must be undone even when exec discards redirection_undo_list. */ +REDIRECT *exec_redirection_undo_list = (REDIRECT *)NULL; + +/* When greater than zero, value is the `level' of builtins we are + currently executing (e.g. `eval echo a' would have it set to 2). */ +int executing_builtin = 0; + +/* Non-zero if we are executing a command list (a;b;c, etc.) */ +int executing_list = 0; + +/* Non-zero if failing commands in a command substitution should not exit the + shell even if -e is set. Used to pass the CMD_IGNORE_RETURN flag down to + commands run in command substitutions by parse_and_execute. */ +int comsub_ignore_return = 0; + +/* Non-zero if we have just forked and are currently running in a subshell + environment. */ +int subshell_environment; + +/* Count of nested subshells, like SHLVL. Available via $BASH_SUBSHELL */ +int subshell_level = 0; + +/* Currently-executing shell function. */ +SHELL_VAR *this_shell_function; + +/* If non-zero, matches in case and [[ ... ]] are case-insensitive */ +int match_ignore_case = 0; + +int executing_command_builtin = 0; + +struct stat SB; /* used for debugging */ + +static int special_builtin_failed; + +static COMMAND *currently_executing_command; + +/* The line number that the currently executing function starts on. */ +static int function_line_number; + +/* XXX - set to 1 if we're running the DEBUG trap and we want to show the line + number containing the function name. Used by executing_line_number to + report the correct line number. Kind of a hack. */ +static int showing_function_line; + +static int line_number_for_err_trap; + +/* A sort of function nesting level counter */ +int funcnest = 0; +int funcnest_max = 0; /* XXX - bash-4.2 */ + +int lastpipe_opt = 0; + +struct fd_bitmap *current_fds_to_close = (struct fd_bitmap *)NULL; + +#define FD_BITMAP_DEFAULT_SIZE 32 + +/* Functions to allocate and deallocate the structures used to pass + information from the shell to its children about file descriptors + to close. */ +struct fd_bitmap * +new_fd_bitmap (size) + int size; +{ + struct fd_bitmap *ret; + + ret = (struct fd_bitmap *)xmalloc (sizeof (struct fd_bitmap)); + + ret->size = size; + + if (size) + { + ret->bitmap = (char *)xmalloc (size); + memset (ret->bitmap, '\0', size); + } + else + ret->bitmap = (char *)NULL; + return (ret); +} + +void +dispose_fd_bitmap (fdbp) + struct fd_bitmap *fdbp; +{ + FREE (fdbp->bitmap); + free (fdbp); +} + +void +close_fd_bitmap (fdbp) + struct fd_bitmap *fdbp; +{ + register int i; + + if (fdbp) + { + for (i = 0; i < fdbp->size; i++) + if (fdbp->bitmap[i]) + { + close (i); + fdbp->bitmap[i] = 0; + } + } +} + +/* Return the line number of the currently executing command. */ +int +executing_line_number () +{ + if (executing && showing_function_line == 0 && + (variable_context == 0 || interactive_shell == 0) && + currently_executing_command) + { +#if defined (COND_COMMAND) + if (currently_executing_command->type == cm_cond) + return currently_executing_command->value.Cond->line; +#endif +#if defined (DPAREN_ARITHMETIC) + else if (currently_executing_command->type == cm_arith) + return currently_executing_command->value.Arith->line; +#endif +#if defined (ARITH_FOR_COMMAND) + else if (currently_executing_command->type == cm_arith_for) + return currently_executing_command->value.ArithFor->line; +#endif + + return line_number; + } + else + return line_number; +} + +/* Execute the command passed in COMMAND. COMMAND is exactly what + read_command () places into GLOBAL_COMMAND. See "command.h" for the + details of the command structure. + + EXECUTION_SUCCESS or EXECUTION_FAILURE are the only possible + return values. Executing a command with nothing in it returns + EXECUTION_SUCCESS. */ +int +execute_command (command) + COMMAND *command; +{ + struct fd_bitmap *bitmap; + int result; + + current_fds_to_close = (struct fd_bitmap *)NULL; + bitmap = new_fd_bitmap (FD_BITMAP_DEFAULT_SIZE); + begin_unwind_frame ("execute-command"); + add_unwind_protect (dispose_fd_bitmap, (char *)bitmap); + + /* Just do the command, but not asynchronously. */ + result = execute_command_internal (command, 0, NO_PIPE, NO_PIPE, bitmap); + + dispose_fd_bitmap (bitmap); + discard_unwind_frame ("execute-command"); + +#if defined (PROCESS_SUBSTITUTION) + /* don't unlink fifos if we're in a shell function; wait until the function + returns. */ + if (variable_context == 0) + unlink_fifo_list (); +#endif /* PROCESS_SUBSTITUTION */ + + QUIT; + return (result); +} + +/* Return 1 if TYPE is a shell control structure type. */ +static int +shell_control_structure (type) + enum command_type type; +{ + switch (type) + { +#if defined (ARITH_FOR_COMMAND) + case cm_arith_for: +#endif +#if defined (SELECT_COMMAND) + case cm_select: +#endif +#if defined (DPAREN_ARITHMETIC) + case cm_arith: +#endif +#if defined (COND_COMMAND) + case cm_cond: +#endif + case cm_case: + case cm_while: + case cm_until: + case cm_if: + case cm_for: + case cm_group: + case cm_function_def: + return (1); + + default: + return (0); + } +} + +/* A function to use to unwind_protect the redirection undo list + for loops. */ +static void +cleanup_redirects (list) + REDIRECT *list; +{ + do_redirections (list, RX_ACTIVE); + dispose_redirects (list); +} + +#if 0 +/* Function to unwind_protect the redirections for functions and builtins. */ +static void +cleanup_func_redirects (list) + REDIRECT *list; +{ + do_redirections (list, RX_ACTIVE); +} +#endif + +void +dispose_exec_redirects () +{ + if (exec_redirection_undo_list) + { + dispose_redirects (exec_redirection_undo_list); + exec_redirection_undo_list = (REDIRECT *)NULL; + } +} + +#if defined (JOB_CONTROL) +/* A function to restore the signal mask to its proper value when the shell + is interrupted or errors occur while creating a pipeline. */ +static int +restore_signal_mask (set) + sigset_t *set; +{ + return (sigprocmask (SIG_SETMASK, set, (sigset_t *)NULL)); +} +#endif /* JOB_CONTROL */ + +#ifdef DEBUG +/* A debugging function that can be called from gdb, for instance. */ +void +open_files () +{ + register int i; + int f, fd_table_size; + + fd_table_size = getdtablesize (); + + fprintf (stderr, "pid %ld open files:", (long)getpid ()); + for (i = 3; i < fd_table_size; i++) + { + if ((f = fcntl (i, F_GETFD, 0)) != -1) + fprintf (stderr, " %d (%s)", i, f ? "close" : "open"); + } + fprintf (stderr, "\n"); +} +#endif + +static void +async_redirect_stdin () +{ + int fd; + + fd = open ("/dev/null", O_RDONLY); + if (fd > 0) + { + dup2 (fd, 0); + close (fd); + } + else if (fd < 0) + internal_error (_("cannot redirect standard input from /dev/null: %s"), strerror (errno)); +} + +#define DESCRIBE_PID(pid) do { if (interactive) describe_pid (pid); } while (0) + +/* Execute the command passed in COMMAND, perhaps doing it asynchrounously. + COMMAND is exactly what read_command () places into GLOBAL_COMMAND. + ASYNCHROUNOUS, if non-zero, says to do this command in the background. + PIPE_IN and PIPE_OUT are file descriptors saying where input comes + from and where it goes. They can have the value of NO_PIPE, which means + I/O is stdin/stdout. + FDS_TO_CLOSE is a list of file descriptors to close once the child has + been forked. This list often contains the unusable sides of pipes, etc. + + EXECUTION_SUCCESS or EXECUTION_FAILURE are the only possible + return values. Executing a command with nothing in it returns + EXECUTION_SUCCESS. */ +int +execute_command_internal (command, asynchronous, pipe_in, pipe_out, + fds_to_close) + COMMAND *command; + int asynchronous; + int pipe_in, pipe_out; + struct fd_bitmap *fds_to_close; +{ + int exec_result, user_subshell, invert, ignore_return, was_error_trap; + REDIRECT *my_undo_list, *exec_undo_list; + volatile int last_pid; + volatile int save_line_number; + +#if 0 + if (command == 0 || breaking || continuing || read_but_dont_execute) + return (EXECUTION_SUCCESS); +#else + if (breaking || continuing) + return (last_command_exit_value); + if (command == 0 || read_but_dont_execute) + return (EXECUTION_SUCCESS); +#endif + + QUIT; + run_pending_traps (); + +#if 0 + if (running_trap == 0) +#endif + currently_executing_command = command; + + invert = (command->flags & CMD_INVERT_RETURN) != 0; + + /* If we're inverting the return value and `set -e' has been executed, + we don't want a failing command to inadvertently cause the shell + to exit. */ + if (exit_immediately_on_error && invert) /* XXX */ + command->flags |= CMD_IGNORE_RETURN; /* XXX */ + + exec_result = EXECUTION_SUCCESS; + + /* If a command was being explicitly run in a subshell, or if it is + a shell control-structure, and it has a pipe, then we do the command + in a subshell. */ + if (command->type == cm_subshell && (command->flags & CMD_NO_FORK)) + return (execute_in_subshell (command, asynchronous, pipe_in, pipe_out, fds_to_close)); + +#if defined (COPROCESS_SUPPORT) + if (command->type == cm_coproc) + return (execute_coproc (command, pipe_in, pipe_out, fds_to_close)); +#endif + + user_subshell = command->type == cm_subshell || ((command->flags & CMD_WANT_SUBSHELL) != 0); + + if (command->type == cm_subshell || + (command->flags & (CMD_WANT_SUBSHELL|CMD_FORCE_SUBSHELL)) || + (shell_control_structure (command->type) && + (pipe_out != NO_PIPE || pipe_in != NO_PIPE || asynchronous))) + { + pid_t paren_pid; + + /* Fork a subshell, turn off the subshell bit, turn off job + control and call execute_command () on the command again. */ + line_number_for_err_trap = line_number; + paren_pid = make_child (savestring (make_command_string (command)), + asynchronous); + if (paren_pid == 0) + exit (execute_in_subshell (command, asynchronous, pipe_in, pipe_out, fds_to_close)); + /* NOTREACHED */ + else + { + close_pipes (pipe_in, pipe_out); + +#if defined (PROCESS_SUBSTITUTION) && defined (HAVE_DEV_FD) + unlink_fifo_list (); +#endif + /* If we are part of a pipeline, and not the end of the pipeline, + then we should simply return and let the last command in the + pipe be waited for. If we are not in a pipeline, or are the + last command in the pipeline, then we wait for the subshell + and return its exit status as usual. */ + if (pipe_out != NO_PIPE) + return (EXECUTION_SUCCESS); + + stop_pipeline (asynchronous, (COMMAND *)NULL); + + if (asynchronous == 0) + { + was_error_trap = signal_is_trapped (ERROR_TRAP) && signal_is_ignored (ERROR_TRAP) == 0; + invert = (command->flags & CMD_INVERT_RETURN) != 0; + ignore_return = (command->flags & CMD_IGNORE_RETURN) != 0; + + exec_result = wait_for (paren_pid); + + /* If we have to, invert the return value. */ + if (invert) + exec_result = ((exec_result == EXECUTION_SUCCESS) + ? EXECUTION_FAILURE + : EXECUTION_SUCCESS); + + last_command_exit_value = exec_result; + if (user_subshell && was_error_trap && ignore_return == 0 && invert == 0 && exec_result != EXECUTION_SUCCESS) + { + save_line_number = line_number; + line_number = line_number_for_err_trap; + run_error_trap (); + line_number = save_line_number; + } + + if (user_subshell && ignore_return == 0 && invert == 0 && exit_immediately_on_error && exec_result != EXECUTION_SUCCESS) + { + run_pending_traps (); + jump_to_top_level (ERREXIT); + } + + return (last_command_exit_value); + } + else + { + DESCRIBE_PID (paren_pid); + + run_pending_traps (); + + return (EXECUTION_SUCCESS); + } + } + } + +#if defined (COMMAND_TIMING) + if (command->flags & CMD_TIME_PIPELINE) + { + if (asynchronous) + { + command->flags |= CMD_FORCE_SUBSHELL; + exec_result = execute_command_internal (command, 1, pipe_in, pipe_out, fds_to_close); + } + else + { + exec_result = time_command (command, asynchronous, pipe_in, pipe_out, fds_to_close); +#if 0 + if (running_trap == 0) +#endif + currently_executing_command = (COMMAND *)NULL; + } + return (exec_result); + } +#endif /* COMMAND_TIMING */ + + if (shell_control_structure (command->type) && command->redirects) + stdin_redir = stdin_redirects (command->redirects); + + /* Handle WHILE FOR CASE etc. with redirections. (Also '&' input + redirection.) */ + if (do_redirections (command->redirects, RX_ACTIVE|RX_UNDOABLE) != 0) + { + cleanup_redirects (redirection_undo_list); + redirection_undo_list = (REDIRECT *)NULL; + dispose_exec_redirects (); + return (last_command_exit_value = EXECUTION_FAILURE); + } + + if (redirection_undo_list) + { + /* XXX - why copy here? */ + my_undo_list = (REDIRECT *)copy_redirects (redirection_undo_list); + dispose_redirects (redirection_undo_list); + redirection_undo_list = (REDIRECT *)NULL; + } + else + my_undo_list = (REDIRECT *)NULL; + + if (exec_redirection_undo_list) + { + /* XXX - why copy here? */ + exec_undo_list = (REDIRECT *)copy_redirects (exec_redirection_undo_list); + dispose_redirects (exec_redirection_undo_list); + exec_redirection_undo_list = (REDIRECT *)NULL; + } + else + exec_undo_list = (REDIRECT *)NULL; + + if (my_undo_list || exec_undo_list) + begin_unwind_frame ("loop_redirections"); + + if (my_undo_list) + add_unwind_protect ((Function *)cleanup_redirects, my_undo_list); + + if (exec_undo_list) + add_unwind_protect ((Function *)dispose_redirects, exec_undo_list); + + ignore_return = (command->flags & CMD_IGNORE_RETURN) != 0; + + QUIT; + + switch (command->type) + { + case cm_simple: + { + save_line_number = line_number; + /* We can't rely on variables retaining their values across a + call to execute_simple_command if a longjmp occurs as the + result of a `return' builtin. This is true for sure with gcc. */ +#if defined (RECYCLES_PIDS) + last_made_pid = NO_PID; +#endif + last_pid = last_made_pid; + was_error_trap = signal_is_trapped (ERROR_TRAP) && signal_is_ignored (ERROR_TRAP) == 0; + + if (ignore_return && command->value.Simple) + command->value.Simple->flags |= CMD_IGNORE_RETURN; + if (command->flags & CMD_STDIN_REDIR) + command->value.Simple->flags |= CMD_STDIN_REDIR; + + line_number_for_err_trap = line_number = command->value.Simple->line; + exec_result = + execute_simple_command (command->value.Simple, pipe_in, pipe_out, + asynchronous, fds_to_close); + line_number = save_line_number; + + /* The temporary environment should be used for only the simple + command immediately following its definition. */ + dispose_used_env_vars (); + +#if (defined (ultrix) && defined (mips)) || defined (C_ALLOCA) + /* Reclaim memory allocated with alloca () on machines which + may be using the alloca emulation code. */ + (void) alloca (0); +#endif /* (ultrix && mips) || C_ALLOCA */ + + /* If we forked to do the command, then we must wait_for () + the child. */ + + /* XXX - this is something to watch out for if there are problems + when the shell is compiled without job control. */ + if (already_making_children && pipe_out == NO_PIPE && + last_made_pid != last_pid) + { + stop_pipeline (asynchronous, (COMMAND *)NULL); + + if (asynchronous) + { + DESCRIBE_PID (last_made_pid); + } + else +#if !defined (JOB_CONTROL) + /* Do not wait for asynchronous processes started from + startup files. */ + if (last_made_pid != last_asynchronous_pid) +#endif + /* When executing a shell function that executes other + commands, this causes the last simple command in + the function to be waited for twice. This also causes + subshells forked to execute builtin commands (e.g., in + pipelines) to be waited for twice. */ + exec_result = wait_for (last_made_pid); + } + } + + /* 2009/02/13 -- pipeline failure is processed elsewhere. This handles + only the failure of a simple command. */ + if (was_error_trap && ignore_return == 0 && invert == 0 && pipe_in == NO_PIPE && pipe_out == NO_PIPE && exec_result != EXECUTION_SUCCESS) + { + last_command_exit_value = exec_result; + line_number = line_number_for_err_trap; + run_error_trap (); + line_number = save_line_number; + } + + if (ignore_return == 0 && invert == 0 && + ((posixly_correct && interactive == 0 && special_builtin_failed) || + (exit_immediately_on_error && pipe_in == NO_PIPE && pipe_out == NO_PIPE && exec_result != EXECUTION_SUCCESS))) + { + last_command_exit_value = exec_result; + run_pending_traps (); + jump_to_top_level (ERREXIT); + } + + break; + + case cm_for: + if (ignore_return) + command->value.For->flags |= CMD_IGNORE_RETURN; + exec_result = execute_for_command (command->value.For); + break; + +#if defined (ARITH_FOR_COMMAND) + case cm_arith_for: + if (ignore_return) + command->value.ArithFor->flags |= CMD_IGNORE_RETURN; + exec_result = execute_arith_for_command (command->value.ArithFor); + break; +#endif + +#if defined (SELECT_COMMAND) + case cm_select: + if (ignore_return) + command->value.Select->flags |= CMD_IGNORE_RETURN; + exec_result = execute_select_command (command->value.Select); + break; +#endif + + case cm_case: + if (ignore_return) + command->value.Case->flags |= CMD_IGNORE_RETURN; + exec_result = execute_case_command (command->value.Case); + break; + + case cm_while: + if (ignore_return) + command->value.While->flags |= CMD_IGNORE_RETURN; + exec_result = execute_while_command (command->value.While); + break; + + case cm_until: + if (ignore_return) + command->value.While->flags |= CMD_IGNORE_RETURN; + exec_result = execute_until_command (command->value.While); + break; + + case cm_if: + if (ignore_return) + command->value.If->flags |= CMD_IGNORE_RETURN; + exec_result = execute_if_command (command->value.If); + break; + + case cm_group: + + /* This code can be executed from either of two paths: an explicit + '{}' command, or via a function call. If we are executed via a + function call, we have already taken care of the function being + executed in the background (down there in execute_simple_command ()), + and this command should *not* be marked as asynchronous. If we + are executing a regular '{}' group command, and asynchronous == 1, + we must want to execute the whole command in the background, so we + need a subshell, and we want the stuff executed in that subshell + (this group command) to be executed in the foreground of that + subshell (i.e. there will not be *another* subshell forked). + + What we do is to force a subshell if asynchronous, and then call + execute_command_internal again with asynchronous still set to 1, + but with the original group command, so the printed command will + look right. + + The code above that handles forking off subshells will note that + both subshell and async are on, and turn off async in the child + after forking the subshell (but leave async set in the parent, so + the normal call to describe_pid is made). This turning off + async is *crucial*; if it is not done, this will fall into an + infinite loop of executions through this spot in subshell after + subshell until the process limit is exhausted. */ + + if (asynchronous) + { + command->flags |= CMD_FORCE_SUBSHELL; + exec_result = + execute_command_internal (command, 1, pipe_in, pipe_out, + fds_to_close); + } + else + { + if (ignore_return && command->value.Group->command) + command->value.Group->command->flags |= CMD_IGNORE_RETURN; + exec_result = + execute_command_internal (command->value.Group->command, + asynchronous, pipe_in, pipe_out, + fds_to_close); + } + break; + + case cm_connection: + exec_result = execute_connection (command, asynchronous, + pipe_in, pipe_out, fds_to_close); + break; + +#if defined (DPAREN_ARITHMETIC) + case cm_arith: + was_error_trap = signal_is_trapped (ERROR_TRAP) && signal_is_ignored (ERROR_TRAP) == 0; + if (ignore_return) + command->value.Arith->flags |= CMD_IGNORE_RETURN; + line_number_for_err_trap = save_line_number = line_number; + exec_result = execute_arith_command (command->value.Arith); + line_number = save_line_number; + + if (was_error_trap && ignore_return == 0 && invert == 0 && exec_result != EXECUTION_SUCCESS) + { + last_command_exit_value = exec_result; + save_line_number = line_number; + line_number = line_number_for_err_trap; + run_error_trap (); + line_number = save_line_number; + } + + if (ignore_return == 0 && invert == 0 && exit_immediately_on_error && exec_result != EXECUTION_SUCCESS) + { + last_command_exit_value = exec_result; + run_pending_traps (); + jump_to_top_level (ERREXIT); + } + + break; +#endif + +#if defined (COND_COMMAND) + case cm_cond: + was_error_trap = signal_is_trapped (ERROR_TRAP) && signal_is_ignored (ERROR_TRAP) == 0; + if (ignore_return) + command->value.Cond->flags |= CMD_IGNORE_RETURN; + + line_number_for_err_trap = save_line_number = line_number; + exec_result = execute_cond_command (command->value.Cond); + line_number = save_line_number; + + if (was_error_trap && ignore_return == 0 && invert == 0 && exec_result != EXECUTION_SUCCESS) + { + last_command_exit_value = exec_result; + save_line_number = line_number; + line_number = line_number_for_err_trap; + run_error_trap (); + line_number = save_line_number; + } + + if (ignore_return == 0 && invert == 0 && exit_immediately_on_error && exec_result != EXECUTION_SUCCESS) + { + last_command_exit_value = exec_result; + run_pending_traps (); + jump_to_top_level (ERREXIT); + } + + break; +#endif + + case cm_function_def: + exec_result = execute_intern_function (command->value.Function_def->name, + command->value.Function_def->command); + break; + + default: + command_error ("execute_command", CMDERR_BADTYPE, command->type, 0); + } + + if (my_undo_list) + { + do_redirections (my_undo_list, RX_ACTIVE); + dispose_redirects (my_undo_list); + } + + if (exec_undo_list) + dispose_redirects (exec_undo_list); + + if (my_undo_list || exec_undo_list) + discard_unwind_frame ("loop_redirections"); + + /* Invert the return value if we have to */ + if (invert) + exec_result = (exec_result == EXECUTION_SUCCESS) + ? EXECUTION_FAILURE + : EXECUTION_SUCCESS; + +#if defined (DPAREN_ARITHMETIC) || defined (COND_COMMAND) + /* This is where we set PIPESTATUS from the exit status of the appropriate + compound commands (the ones that look enough like simple commands to + cause confusion). We might be able to optimize by not doing this if + subshell_environment != 0. */ + switch (command->type) + { +# if defined (DPAREN_ARITHMETIC) + case cm_arith: +# endif +# if defined (COND_COMMAND) + case cm_cond: +# endif + set_pipestatus_from_exit (exec_result); + break; + } +#endif + + last_command_exit_value = exec_result; + run_pending_traps (); +#if 0 + if (running_trap == 0) +#endif + currently_executing_command = (COMMAND *)NULL; + return (last_command_exit_value); +} + +#if defined (COMMAND_TIMING) + +#if defined (HAVE_GETRUSAGE) && defined (HAVE_GETTIMEOFDAY) +extern struct timeval *difftimeval __P((struct timeval *, struct timeval *, struct timeval *)); +extern struct timeval *addtimeval __P((struct timeval *, struct timeval *, struct timeval *)); +extern int timeval_to_cpu __P((struct timeval *, struct timeval *, struct timeval *)); +#endif + +#define POSIX_TIMEFORMAT "real %2R\nuser %2U\nsys %2S" +#define BASH_TIMEFORMAT "\nreal\t%3lR\nuser\t%3lU\nsys\t%3lS" + +static const int precs[] = { 0, 100, 10, 1 }; + +/* Expand one `%'-prefixed escape sequence from a time format string. */ +static int +mkfmt (buf, prec, lng, sec, sec_fraction) + char *buf; + int prec, lng; + time_t sec; + int sec_fraction; +{ + time_t min; + char abuf[INT_STRLEN_BOUND(time_t) + 1]; + int ind, aind; + + ind = 0; + abuf[sizeof(abuf) - 1] = '\0'; + + /* If LNG is non-zero, we want to decompose SEC into minutes and seconds. */ + if (lng) + { + min = sec / 60; + sec %= 60; + aind = sizeof(abuf) - 2; + do + abuf[aind--] = (min % 10) + '0'; + while (min /= 10); + aind++; + while (abuf[aind]) + buf[ind++] = abuf[aind++]; + buf[ind++] = 'm'; + } + + /* Now add the seconds. */ + aind = sizeof (abuf) - 2; + do + abuf[aind--] = (sec % 10) + '0'; + while (sec /= 10); + aind++; + while (abuf[aind]) + buf[ind++] = abuf[aind++]; + + /* We want to add a decimal point and PREC places after it if PREC is + nonzero. PREC is not greater than 3. SEC_FRACTION is between 0 + and 999. */ + if (prec != 0) + { + buf[ind++] = '.'; + for (aind = 1; aind <= prec; aind++) + { + buf[ind++] = (sec_fraction / precs[aind]) + '0'; + sec_fraction %= precs[aind]; + } + } + + if (lng) + buf[ind++] = 's'; + buf[ind] = '\0'; + + return (ind); +} + +/* Interpret the format string FORMAT, interpolating the following escape + sequences: + %[prec][l][RUS] + + where the optional `prec' is a precision, meaning the number of + characters after the decimal point, the optional `l' means to format + using minutes and seconds (MMmNN[.FF]s), like the `times' builtin', + and the last character is one of + + R number of seconds of `real' time + U number of seconds of `user' time + S number of seconds of `system' time + + An occurrence of `%%' in the format string is translated to a `%'. The + result is printed to FP, a pointer to a FILE. The other variables are + the seconds and thousandths of a second of real, user, and system time, + resectively. */ +static void +print_formatted_time (fp, format, rs, rsf, us, usf, ss, ssf, cpu) + FILE *fp; + char *format; + time_t rs; + int rsf; + time_t us; + int usf; + time_t ss; + int ssf, cpu; +{ + int prec, lng, len; + char *str, *s, ts[INT_STRLEN_BOUND (time_t) + sizeof ("mSS.FFFF")]; + time_t sum; + int sum_frac; + int sindex, ssize; + + len = strlen (format); + ssize = (len + 64) - (len % 64); + str = (char *)xmalloc (ssize); + sindex = 0; + + for (s = format; *s; s++) + { + if (*s != '%' || s[1] == '\0') + { + RESIZE_MALLOCED_BUFFER (str, sindex, 1, ssize, 64); + str[sindex++] = *s; + } + else if (s[1] == '%') + { + s++; + RESIZE_MALLOCED_BUFFER (str, sindex, 1, ssize, 64); + str[sindex++] = *s; + } + else if (s[1] == 'P') + { + s++; +#if 0 + /* clamp CPU usage at 100% */ + if (cpu > 10000) + cpu = 10000; +#endif + sum = cpu / 100; + sum_frac = (cpu % 100) * 10; + len = mkfmt (ts, 2, 0, sum, sum_frac); + RESIZE_MALLOCED_BUFFER (str, sindex, len, ssize, 64); + strcpy (str + sindex, ts); + sindex += len; + } + else + { + prec = 3; /* default is three places past the decimal point. */ + lng = 0; /* default is to not use minutes or append `s' */ + s++; + if (DIGIT (*s)) /* `precision' */ + { + prec = *s++ - '0'; + if (prec > 3) prec = 3; + } + if (*s == 'l') /* `length extender' */ + { + lng = 1; + s++; + } + if (*s == 'R' || *s == 'E') + len = mkfmt (ts, prec, lng, rs, rsf); + else if (*s == 'U') + len = mkfmt (ts, prec, lng, us, usf); + else if (*s == 'S') + len = mkfmt (ts, prec, lng, ss, ssf); + else + { + internal_error (_("TIMEFORMAT: `%c': invalid format character"), *s); + free (str); + return; + } + RESIZE_MALLOCED_BUFFER (str, sindex, len, ssize, 64); + strcpy (str + sindex, ts); + sindex += len; + } + } + + str[sindex] = '\0'; + fprintf (fp, "%s\n", str); + fflush (fp); + + free (str); +} + +static int +time_command (command, asynchronous, pipe_in, pipe_out, fds_to_close) + COMMAND *command; + int asynchronous, pipe_in, pipe_out; + struct fd_bitmap *fds_to_close; +{ + int rv, posix_time, old_flags, nullcmd; + time_t rs, us, ss; + int rsf, usf, ssf; + int cpu; + char *time_format; + +#if defined (HAVE_GETRUSAGE) && defined (HAVE_GETTIMEOFDAY) + struct timeval real, user, sys; + struct timeval before, after; +# if defined (HAVE_STRUCT_TIMEZONE) + struct timezone dtz; /* posix doesn't define this */ +# endif + struct rusage selfb, selfa, kidsb, kidsa; /* a = after, b = before */ +#else +# if defined (HAVE_TIMES) + clock_t tbefore, tafter, real, user, sys; + struct tms before, after; +# endif +#endif + +#if defined (HAVE_GETRUSAGE) && defined (HAVE_GETTIMEOFDAY) +# if defined (HAVE_STRUCT_TIMEZONE) + gettimeofday (&before, &dtz); +# else + gettimeofday (&before, (void *)NULL); +# endif /* !HAVE_STRUCT_TIMEZONE */ + getrusage (RUSAGE_SELF, &selfb); + getrusage (RUSAGE_CHILDREN, &kidsb); +#else +# if defined (HAVE_TIMES) + tbefore = times (&before); +# endif +#endif + + posix_time = (command->flags & CMD_TIME_POSIX); + + nullcmd = (command == 0) || (command->type == cm_simple && command->value.Simple->words == 0 && command->value.Simple->redirects == 0); + if (posixly_correct && nullcmd) + { +#if defined (HAVE_GETRUSAGE) + selfb.ru_utime.tv_sec = kidsb.ru_utime.tv_sec = selfb.ru_stime.tv_sec = kidsb.ru_stime.tv_sec = 0; + selfb.ru_utime.tv_usec = kidsb.ru_utime.tv_usec = selfb.ru_stime.tv_usec = kidsb.ru_stime.tv_usec = 0; + before.tv_sec = shell_start_time; + before.tv_usec = 0; +#else + before.tms_utime = before.tms_stime = before.tms_cutime = before.tms_cstime = 0; + tbefore = shell_start_time; +#endif + } + + old_flags = command->flags; + command->flags &= ~(CMD_TIME_PIPELINE|CMD_TIME_POSIX); + rv = execute_command_internal (command, asynchronous, pipe_in, pipe_out, fds_to_close); + command->flags = old_flags; + + rs = us = ss = 0; + rsf = usf = ssf = cpu = 0; + +#if defined (HAVE_GETRUSAGE) && defined (HAVE_GETTIMEOFDAY) +# if defined (HAVE_STRUCT_TIMEZONE) + gettimeofday (&after, &dtz); +# else + gettimeofday (&after, (void *)NULL); +# endif /* !HAVE_STRUCT_TIMEZONE */ + getrusage (RUSAGE_SELF, &selfa); + getrusage (RUSAGE_CHILDREN, &kidsa); + + difftimeval (&real, &before, &after); + timeval_to_secs (&real, &rs, &rsf); + + addtimeval (&user, difftimeval(&after, &selfb.ru_utime, &selfa.ru_utime), + difftimeval(&before, &kidsb.ru_utime, &kidsa.ru_utime)); + timeval_to_secs (&user, &us, &usf); + + addtimeval (&sys, difftimeval(&after, &selfb.ru_stime, &selfa.ru_stime), + difftimeval(&before, &kidsb.ru_stime, &kidsa.ru_stime)); + timeval_to_secs (&sys, &ss, &ssf); + + cpu = timeval_to_cpu (&real, &user, &sys); +#else +# if defined (HAVE_TIMES) + tafter = times (&after); + + real = tafter - tbefore; + clock_t_to_secs (real, &rs, &rsf); + + user = (after.tms_utime - before.tms_utime) + (after.tms_cutime - before.tms_cutime); + clock_t_to_secs (user, &us, &usf); + + sys = (after.tms_stime - before.tms_stime) + (after.tms_cstime - before.tms_cstime); + clock_t_to_secs (sys, &ss, &ssf); + + cpu = (real == 0) ? 0 : ((user + sys) * 10000) / real; + +# else + rs = us = ss = 0; + rsf = usf = ssf = cpu = 0; +# endif +#endif + + if (posix_time) + time_format = POSIX_TIMEFORMAT; + else if ((time_format = get_string_value ("TIMEFORMAT")) == 0) + { + if (posixly_correct && nullcmd) + time_format = "user\t%2lU\nsys\t%2lS"; + else + time_format = BASH_TIMEFORMAT; + } + if (time_format && *time_format) + print_formatted_time (stderr, time_format, rs, rsf, us, usf, ss, ssf, cpu); + + return rv; +} +#endif /* COMMAND_TIMING */ + +/* Execute a command that's supposed to be in a subshell. This must be + called after make_child and we must be running in the child process. + The caller will return or exit() immediately with the value this returns. */ +static int +execute_in_subshell (command, asynchronous, pipe_in, pipe_out, fds_to_close) + COMMAND *command; + int asynchronous; + int pipe_in, pipe_out; + struct fd_bitmap *fds_to_close; +{ + int user_subshell, return_code, function_value, should_redir_stdin, invert; + int ois, user_coproc; + int result; + volatile COMMAND *tcom; + + USE_VAR(user_subshell); + USE_VAR(user_coproc); + USE_VAR(invert); + USE_VAR(tcom); + USE_VAR(asynchronous); + + subshell_level++; + should_redir_stdin = (asynchronous && (command->flags & CMD_STDIN_REDIR) && + pipe_in == NO_PIPE && + stdin_redirects (command->redirects) == 0); + + invert = (command->flags & CMD_INVERT_RETURN) != 0; + user_subshell = command->type == cm_subshell || ((command->flags & CMD_WANT_SUBSHELL) != 0); + user_coproc = command->type == cm_coproc; + + command->flags &= ~(CMD_FORCE_SUBSHELL | CMD_WANT_SUBSHELL | CMD_INVERT_RETURN); + + /* If a command is asynchronous in a subshell (like ( foo ) & or + the special case of an asynchronous GROUP command where the + the subshell bit is turned on down in case cm_group: below), + turn off `asynchronous', so that two subshells aren't spawned. + XXX - asynchronous used to be set to 0 in this block, but that + means that setup_async_signals was never run. Now it's set to + 0 after subshell_environment is set appropriately and setup_async_signals + is run. + + This seems semantically correct to me. For example, + ( foo ) & seems to say ``do the command `foo' in a subshell + environment, but don't wait for that subshell to finish'', + and "{ foo ; bar ; } &" seems to me to be like functions or + builtins in the background, which executed in a subshell + environment. I just don't see the need to fork two subshells. */ + + /* Don't fork again, we are already in a subshell. A `doubly + async' shell is not interactive, however. */ + if (asynchronous) + { +#if defined (JOB_CONTROL) + /* If a construct like ( exec xxx yyy ) & is given while job + control is active, we want to prevent exec from putting the + subshell back into the original process group, carefully + undoing all the work we just did in make_child. */ + original_pgrp = -1; +#endif /* JOB_CONTROL */ + ois = interactive_shell; + interactive_shell = 0; + /* This test is to prevent alias expansion by interactive shells that + run `(command) &' but to allow scripts that have enabled alias + expansion with `shopt -s expand_alias' to continue to expand + aliases. */ + if (ois != interactive_shell) + expand_aliases = 0; + } + + /* Subshells are neither login nor interactive. */ + login_shell = interactive = 0; + + if (user_subshell) + subshell_environment = SUBSHELL_PAREN; + else + { + subshell_environment = 0; /* XXX */ + if (asynchronous) + subshell_environment |= SUBSHELL_ASYNC; + if (pipe_in != NO_PIPE || pipe_out != NO_PIPE) + subshell_environment |= SUBSHELL_PIPE; + if (user_coproc) + subshell_environment |= SUBSHELL_COPROC; + } + + reset_terminating_signals (); /* in sig.c */ + /* Cancel traps, in trap.c. */ + /* Reset the signal handlers in the child, but don't free the + trap strings. Set a flag noting that we have to free the + trap strings if we run trap to change a signal disposition. */ + reset_signal_handlers (); + subshell_environment |= SUBSHELL_RESETTRAP; + + /* Make sure restore_original_signals doesn't undo the work done by + make_child to ensure that asynchronous children are immune to SIGINT + and SIGQUIT. Turn off asynchronous to make sure more subshells are + not spawned. */ + if (asynchronous) + { + setup_async_signals (); + asynchronous = 0; + } + +#if defined (JOB_CONTROL) + set_sigchld_handler (); +#endif /* JOB_CONTROL */ + + set_sigint_handler (); + +#if defined (JOB_CONTROL) + /* Delete all traces that there were any jobs running. This is + only for subshells. */ + without_job_control (); +#endif /* JOB_CONTROL */ + + if (fds_to_close) + close_fd_bitmap (fds_to_close); + + do_piping (pipe_in, pipe_out); + +#if defined (COPROCESS_SUPPORT) + coproc_closeall (); +#endif + + /* If this is a user subshell, set a flag if stdin was redirected. + This is used later to decide whether to redirect fd 0 to + /dev/null for async commands in the subshell. This adds more + sh compatibility, but I'm not sure it's the right thing to do. */ + if (user_subshell) + { + stdin_redir = stdin_redirects (command->redirects); + restore_default_signal (0); + } + + /* If this is an asynchronous command (command &), we want to + redirect the standard input from /dev/null in the absence of + any specific redirection involving stdin. */ + if (should_redir_stdin && stdin_redir == 0) + async_redirect_stdin (); + + /* Do redirections, then dispose of them before recursive call. */ + if (command->redirects) + { + if (do_redirections (command->redirects, RX_ACTIVE) != 0) + exit (invert ? EXECUTION_SUCCESS : EXECUTION_FAILURE); + + dispose_redirects (command->redirects); + command->redirects = (REDIRECT *)NULL; + } + + if (command->type == cm_subshell) + tcom = command->value.Subshell->command; + else if (user_coproc) + tcom = command->value.Coproc->command; + else + tcom = command; + + if (command->flags & CMD_TIME_PIPELINE) + tcom->flags |= CMD_TIME_PIPELINE; + if (command->flags & CMD_TIME_POSIX) + tcom->flags |= CMD_TIME_POSIX; + + /* Make sure the subshell inherits any CMD_IGNORE_RETURN flag. */ + if ((command->flags & CMD_IGNORE_RETURN) && tcom != command) + tcom->flags |= CMD_IGNORE_RETURN; + + /* If this is a simple command, tell execute_disk_command that it + might be able to get away without forking and simply exec. + This means things like ( sleep 10 ) will only cause one fork. + If we're timing the command or inverting its return value, however, + we cannot do this optimization. */ + if ((user_subshell || user_coproc) && (tcom->type == cm_simple || tcom->type == cm_subshell) && + ((tcom->flags & CMD_TIME_PIPELINE) == 0) && + ((tcom->flags & CMD_INVERT_RETURN) == 0)) + { + tcom->flags |= CMD_NO_FORK; + if (tcom->type == cm_simple) + tcom->value.Simple->flags |= CMD_NO_FORK; + } + + invert = (tcom->flags & CMD_INVERT_RETURN) != 0; + tcom->flags &= ~CMD_INVERT_RETURN; + + result = setjmp (top_level); + + /* If we're inside a function while executing this subshell, we + need to handle a possible `return'. */ + function_value = 0; + if (return_catch_flag) + function_value = setjmp (return_catch); + + /* If we're going to exit the shell, we don't want to invert the return + status. */ + if (result == EXITPROG) + invert = 0, return_code = last_command_exit_value; + else if (result) + return_code = EXECUTION_FAILURE; + else if (function_value) + return_code = return_catch_value; + else + return_code = execute_command_internal ((COMMAND *)tcom, asynchronous, NO_PIPE, NO_PIPE, fds_to_close); + + /* If we are asked to, invert the return value. */ + if (invert) + return_code = (return_code == EXECUTION_SUCCESS) ? EXECUTION_FAILURE + : EXECUTION_SUCCESS; + + /* If we were explicitly placed in a subshell with (), we need + to do the `shell cleanup' things, such as running traps[0]. */ + if (user_subshell && signal_is_trapped (0)) + { + last_command_exit_value = return_code; + return_code = run_exit_trap (); + } + + subshell_level--; + return (return_code); + /* NOTREACHED */ +} + +#if defined (COPROCESS_SUPPORT) +#define COPROC_MAX 16 + +typedef struct cpelement + { + struct cpelement *next; + struct coproc *coproc; + } +cpelement_t; + +typedef struct cplist + { + struct cpelement *head; + struct cpelement *tail; + int ncoproc; + } +cplist_t; + +static struct cpelement *cpe_alloc __P((struct coproc *)); +static void cpe_dispose __P((struct cpelement *)); +static struct cpelement *cpl_add __P((struct coproc *)); +static struct cpelement *cpl_delete __P((pid_t)); +static void cpl_reap __P((void)); +static void cpl_flush __P((void)); +static void cpl_closeall __P((void)); +static struct cpelement *cpl_search __P((pid_t)); +static struct cpelement *cpl_searchbyname __P((const char *)); +static void cpl_prune __P((void)); + +static void coproc_free __P((struct coproc *)); + +/* Will go away when there is fully-implemented support for multiple coprocs. */ +Coproc sh_coproc = { 0, NO_PID, -1, -1, 0, 0, 0, 0 }; + +cplist_t coproc_list = {0, 0, 0}; + +/* Functions to manage the list of coprocs */ + +static struct cpelement * +cpe_alloc (cp) + Coproc *cp; +{ + struct cpelement *cpe; + + cpe = (struct cpelement *)xmalloc (sizeof (struct cpelement)); + cpe->coproc = cp; + cpe->next = (struct cpelement *)0; + return cpe; +} + +static void +cpe_dispose (cpe) + struct cpelement *cpe; +{ + free (cpe); +} + +static struct cpelement * +cpl_add (cp) + Coproc *cp; +{ + struct cpelement *cpe; + + cpe = cpe_alloc (cp); + + if (coproc_list.head == 0) + { + coproc_list.head = coproc_list.tail = cpe; + coproc_list.ncoproc = 0; /* just to make sure */ + } + else + { + coproc_list.tail->next = cpe; + coproc_list.tail = cpe; + } + coproc_list.ncoproc++; + + return cpe; +} + +static struct cpelement * +cpl_delete (pid) + pid_t pid; +{ + struct cpelement *prev, *p; + + for (prev = p = coproc_list.head; p; prev = p, p = p->next) + if (p->coproc->c_pid == pid) + { + prev->next = p->next; /* remove from list */ + break; + } + + if (p == 0) + return 0; /* not found */ + +#if defined (DEBUG) + itrace("cpl_delete: deleting %d", pid); +#endif + + /* Housekeeping in the border cases. */ + if (p == coproc_list.head) + coproc_list.head = coproc_list.head->next; + else if (p == coproc_list.tail) + coproc_list.tail = prev; + + coproc_list.ncoproc--; + if (coproc_list.ncoproc == 0) + coproc_list.head = coproc_list.tail = 0; + else if (coproc_list.ncoproc == 1) + coproc_list.tail = coproc_list.head; /* just to make sure */ + + return (p); +} + +static void +cpl_reap () +{ + struct cpelement *prev, *p; + + for (prev = p = coproc_list.head; p; prev = p, p = p->next) + if (p->coproc->c_flags & COPROC_DEAD) + { + prev->next = p->next; /* remove from list */ + + /* Housekeeping in the border cases. */ + if (p == coproc_list.head) + coproc_list.head = coproc_list.head->next; + else if (p == coproc_list.tail) + coproc_list.tail = prev; + + coproc_list.ncoproc--; + if (coproc_list.ncoproc == 0) + coproc_list.head = coproc_list.tail = 0; + else if (coproc_list.ncoproc == 1) + coproc_list.tail = coproc_list.head; /* just to make sure */ + +#if defined (DEBUG) + itrace("cpl_reap: deleting %d", p->coproc->c_pid); +#endif + + coproc_dispose (p->coproc); + cpe_dispose (p); + } +} + +/* Clear out the list of saved statuses */ +static void +cpl_flush () +{ + struct cpelement *cpe, *p; + + for (cpe = coproc_list.head; cpe; ) + { + p = cpe; + cpe = cpe->next; + + coproc_dispose (p->coproc); + cpe_dispose (p); + } + + coproc_list.head = coproc_list.tail = 0; + coproc_list.ncoproc = 0; +} + +static void +cpl_closeall () +{ + struct cpelement *cpe; + + for (cpe = coproc_list.head; cpe; cpe = cpe->next) + coproc_close (cpe->coproc); +} + +static void +cpl_fdchk (fd) + int fd; +{ + struct cpelement *cpe; + + for (cpe = coproc_list.head; cpe; cpe = cpe->next) + coproc_checkfd (cpe->coproc, fd); +} + +/* Search for PID in the list of coprocs; return the cpelement struct if + found. If not found, return NULL. */ +static struct cpelement * +cpl_search (pid) + pid_t pid; +{ + struct cpelement *cpe; + + for (cpe = coproc_list.head ; cpe; cpe = cpe->next) + if (cpe->coproc->c_pid == pid) + return cpe; + return (struct cpelement *)NULL; +} + +/* Search for the coproc named NAME in the list of coprocs; return the + cpelement struct if found. If not found, return NULL. */ +static struct cpelement * +cpl_searchbyname (name) + const char *name; +{ + struct cpelement *cp; + + for (cp = coproc_list.head ; cp; cp = cp->next) + if (STREQ (cp->coproc->c_name, name)) + return cp; + return (struct cpelement *)NULL; +} + +#if 0 +static void +cpl_prune () +{ + struct cpelement *cp; + + while (coproc_list.head && coproc_list.ncoproc > COPROC_MAX) + { + cp = coproc_list.head; + coproc_list.head = coproc_list.head->next; + coproc_dispose (cp->coproc); + cpe_dispose (cp); + coproc_list.ncoproc--; + } +} +#endif + +/* These currently use a single global "shell coproc" but are written in a + way to not preclude additional coprocs later (using the list management + package above). */ + +struct coproc * +getcoprocbypid (pid) + pid_t pid; +{ +#if MULTIPLE_COPROCS + struct cpelement *p; + + p = cpl_search (pid); + return (p ? p->coproc : 0); +#else + return (pid == sh_coproc.c_pid ? &sh_coproc : 0); +#endif +} + +struct coproc * +getcoprocbyname (name) + const char *name; +{ +#if MULTIPLE_COPROCS + struct cpelement *p; + + p = cpl_searchbyname (name); + return (p ? p->coproc : 0); +#else + return ((sh_coproc.c_name && STREQ (sh_coproc.c_name, name)) ? &sh_coproc : 0); +#endif +} + +void +coproc_init (cp) + struct coproc *cp; +{ + cp->c_name = 0; + cp->c_pid = NO_PID; + cp->c_rfd = cp->c_wfd = -1; + cp->c_rsave = cp->c_wsave = -1; + cp->c_flags = cp->c_status = 0; +} + +struct coproc * +coproc_alloc (name, pid) + char *name; + pid_t pid; +{ + struct coproc *cp; + +#if MULTIPLE_COPROCS + cp = (struct coproc *)xmalloc (sizeof (struct coproc)); +#else + cp = &sh_coproc; +#endif + coproc_init (cp); + + cp->c_name = savestring (name); + cp->c_pid = pid; + +#if MULTIPLE_COPROCS + cpl_add (cp); +#endif + + return (cp); +} + +static void +coproc_free (cp) + struct coproc *cp; +{ + free (cp); +} + +void +coproc_dispose (cp) + struct coproc *cp; +{ + if (cp == 0) + return; + + coproc_unsetvars (cp); + FREE (cp->c_name); + coproc_close (cp); +#if MULTIPLE_COPROCS + coproc_free (cp); +#else + coproc_init (cp); +#endif +} + +/* Placeholder for now. Will require changes for multiple coprocs */ +void +coproc_flush () +{ +#if MULTIPLE_COPROCS + cpl_flush (); +#else + coproc_dispose (&sh_coproc); +#endif +} + +void +coproc_close (cp) + struct coproc *cp; +{ + if (cp->c_rfd >= 0) + { + close (cp->c_rfd); + cp->c_rfd = -1; + } + if (cp->c_wfd >= 0) + { + close (cp->c_wfd); + cp->c_wfd = -1; + } + cp->c_rsave = cp->c_wsave = -1; +} + +void +coproc_closeall () +{ +#if MULTIPLE_COPROCS + cpl_closeall (); +#else + coproc_close (&sh_coproc); /* XXX - will require changes for multiple coprocs */ +#endif +} + +void +coproc_reap () +{ +#if MULTIPLE_COPROCS + cpl_reap (); +#else + struct coproc *cp; + + cp = &sh_coproc; /* XXX - will require changes for multiple coprocs */ + if (cp && (cp->c_flags & COPROC_DEAD)) + coproc_dispose (cp); +#endif +} + +void +coproc_rclose (cp, fd) + struct coproc *cp; + int fd; +{ + if (cp->c_rfd >= 0 && cp->c_rfd == fd) + { + close (cp->c_rfd); + cp->c_rfd = -1; + } +} + +void +coproc_wclose (cp, fd) + struct coproc *cp; + int fd; +{ + if (cp->c_wfd >= 0 && cp->c_wfd == fd) + { + close (cp->c_wfd); + cp->c_wfd = -1; + } +} + +void +coproc_checkfd (cp, fd) + struct coproc *cp; + int fd; +{ + int update; + + update = 0; + if (cp->c_rfd >= 0 && cp->c_rfd == fd) + update = cp->c_rfd = -1; + if (cp->c_wfd >= 0 && cp->c_wfd == fd) + update = cp->c_wfd = -1; + if (update) + coproc_setvars (cp); +} + +void +coproc_fdchk (fd) + int fd; +{ +#if MULTIPLE_COPROCS + cpl_fdchk (fd); +#else + coproc_checkfd (&sh_coproc, fd); +#endif +} + +void +coproc_fdclose (cp, fd) + struct coproc *cp; + int fd; +{ + coproc_rclose (cp, fd); + coproc_wclose (cp, fd); + coproc_setvars (cp); +} + +void +coproc_fdsave (cp) + struct coproc *cp; +{ + cp->c_rsave = cp->c_rfd; + cp->c_wsave = cp->c_wfd; +} + +void +coproc_fdrestore (cp) + struct coproc *cp; +{ + cp->c_rfd = cp->c_rsave; + cp->c_wfd = cp->c_wsave; +} + +void +coproc_pidchk (pid, status) + pid_t pid; +{ + struct coproc *cp; + +#if MULTIPLE_COPROCS + struct cpelement *cpe; + + cpe = cpl_delete (pid); + cp = cpe ? cpe->coproc : 0; +#else + cp = getcoprocbypid (pid); +#endif + if (cp) + { +#if 0 + itrace("coproc_pidchk: pid %d has died", pid); +#endif + cp->c_status = status; + cp->c_flags |= COPROC_DEAD; + cp->c_flags &= ~COPROC_RUNNING; +#if MULTIPLE_COPROCS + coproc_dispose (cp); +#else + coproc_unsetvars (cp); +#endif + } +} + +void +coproc_setvars (cp) + struct coproc *cp; +{ + SHELL_VAR *v; + char *namevar, *t; + int l; +#if defined (ARRAY_VARS) + arrayind_t ind; +#endif + + if (cp->c_name == 0) + return; + + l = strlen (cp->c_name); + namevar = xmalloc (l + 16); + +#if defined (ARRAY_VARS) + v = find_variable (cp->c_name); + if (v == 0) + v = make_new_array_variable (cp->c_name); + if (array_p (v) == 0) + v = convert_var_to_array (v); + + t = itos (cp->c_rfd); + ind = 0; + v = bind_array_variable (cp->c_name, ind, t, 0); + free (t); + + t = itos (cp->c_wfd); + ind = 1; + bind_array_variable (cp->c_name, ind, t, 0); + free (t); +#else + sprintf (namevar, "%s_READ", cp->c_name); + t = itos (cp->c_rfd); + bind_variable (namevar, t, 0); + free (t); + sprintf (namevar, "%s_WRITE", cp->c_name); + t = itos (cp->c_wfd); + bind_variable (namevar, t, 0); + free (t); +#endif + + sprintf (namevar, "%s_PID", cp->c_name); + t = itos (cp->c_pid); + bind_variable (namevar, t, 0); + free (t); + + free (namevar); +} + +void +coproc_unsetvars (cp) + struct coproc *cp; +{ + int l; + char *namevar; + + if (cp->c_name == 0) + return; + + l = strlen (cp->c_name); + namevar = xmalloc (l + 16); + + sprintf (namevar, "%s_PID", cp->c_name); + unbind_variable (namevar); + +#if defined (ARRAY_VARS) + unbind_variable (cp->c_name); +#else + sprintf (namevar, "%s_READ", cp->c_name); + unbind_variable (namevar); + sprintf (namevar, "%s_WRITE", cp->c_name); + unbind_variable (namevar); +#endif + + free (namevar); +} + +static int +execute_coproc (command, pipe_in, pipe_out, fds_to_close) + COMMAND *command; + int pipe_in, pipe_out; + struct fd_bitmap *fds_to_close; +{ + int rpipe[2], wpipe[2], estat; + pid_t coproc_pid; + Coproc *cp; + char *tcmd; + + /* XXX -- can be removed after changes to handle multiple coprocs */ +#if !MULTIPLE_COPROCS + if (sh_coproc.c_pid != NO_PID) + internal_warning ("execute_coproc: coproc [%d:%s] still exists", sh_coproc.c_pid, sh_coproc.c_name); + coproc_init (&sh_coproc); +#endif + + command_string_index = 0; + tcmd = make_command_string (command); + + sh_openpipe ((int *)&rpipe); /* 0 = parent read, 1 = child write */ + sh_openpipe ((int *)&wpipe); /* 0 = child read, 1 = parent write */ + + coproc_pid = make_child (savestring (tcmd), 1); + if (coproc_pid == 0) + { + close (rpipe[0]); + close (wpipe[1]); + + estat = execute_in_subshell (command, 1, wpipe[0], rpipe[1], fds_to_close); + + fflush (stdout); + fflush (stderr); + + exit (estat); + } + + close (rpipe[1]); + close (wpipe[0]); + + cp = coproc_alloc (command->value.Coproc->name, coproc_pid); + cp->c_rfd = rpipe[0]; + cp->c_wfd = wpipe[1]; + + SET_CLOSE_ON_EXEC (cp->c_rfd); + SET_CLOSE_ON_EXEC (cp->c_wfd); + + coproc_setvars (cp); + +#if 0 + itrace ("execute_coproc: [%d] %s", coproc_pid, the_printed_command); +#endif + + close_pipes (pipe_in, pipe_out); +#if defined (PROCESS_SUBSTITUTION) && defined (HAVE_DEV_FD) + unlink_fifo_list (); +#endif + stop_pipeline (1, (COMMAND *)NULL); + DESCRIBE_PID (coproc_pid); + run_pending_traps (); + + return (EXECUTION_SUCCESS); +} +#endif + +static void +restore_stdin (s) + int s; +{ + dup2 (s, 0); + close (s); +} + +/* Catch-all cleanup function for lastpipe code for unwind-protects */ +static void +lastpipe_cleanup (s) + int s; +{ + unfreeze_jobs_list (); +} + +static int +execute_pipeline (command, asynchronous, pipe_in, pipe_out, fds_to_close) + COMMAND *command; + int asynchronous, pipe_in, pipe_out; + struct fd_bitmap *fds_to_close; +{ + int prev, fildes[2], new_bitmap_size, dummyfd, ignore_return, exec_result; + int lstdin, lastpipe_flag, lastpipe_jid; + COMMAND *cmd; + struct fd_bitmap *fd_bitmap; + pid_t lastpid; + +#if defined (JOB_CONTROL) + sigset_t set, oset; + BLOCK_CHILD (set, oset); +#endif /* JOB_CONTROL */ + + ignore_return = (command->flags & CMD_IGNORE_RETURN) != 0; + + prev = pipe_in; + cmd = command; + + while (cmd && cmd->type == cm_connection && + cmd->value.Connection && cmd->value.Connection->connector == '|') + { + /* Make a pipeline between the two commands. */ + if (pipe (fildes) < 0) + { + sys_error (_("pipe error")); +#if defined (JOB_CONTROL) + terminate_current_pipeline (); + kill_current_pipeline (); + UNBLOCK_CHILD (oset); +#endif /* JOB_CONTROL */ + last_command_exit_value = EXECUTION_FAILURE; + /* The unwind-protects installed below will take care + of closing all of the open file descriptors. */ + throw_to_top_level (); + return (EXECUTION_FAILURE); /* XXX */ + } + + /* Here is a problem: with the new file close-on-exec + code, the read end of the pipe (fildes[0]) stays open + in the first process, so that process will never get a + SIGPIPE. There is no way to signal the first process + that it should close fildes[0] after forking, so it + remains open. No SIGPIPE is ever sent because there + is still a file descriptor open for reading connected + to the pipe. We take care of that here. This passes + around a bitmap of file descriptors that must be + closed after making a child process in execute_simple_command. */ + + /* We need fd_bitmap to be at least as big as fildes[0]. + If fildes[0] is less than fds_to_close->size, then + use fds_to_close->size. */ + new_bitmap_size = (fildes[0] < fds_to_close->size) + ? fds_to_close->size + : fildes[0] + 8; + + fd_bitmap = new_fd_bitmap (new_bitmap_size); + + /* Now copy the old information into the new bitmap. */ + xbcopy ((char *)fds_to_close->bitmap, (char *)fd_bitmap->bitmap, fds_to_close->size); + + /* And mark the pipe file descriptors to be closed. */ + fd_bitmap->bitmap[fildes[0]] = 1; + + /* In case there are pipe or out-of-processes errors, we + want all these file descriptors to be closed when + unwind-protects are run, and the storage used for the + bitmaps freed up. */ + begin_unwind_frame ("pipe-file-descriptors"); + add_unwind_protect (dispose_fd_bitmap, fd_bitmap); + add_unwind_protect (close_fd_bitmap, fd_bitmap); + if (prev >= 0) + add_unwind_protect (close, prev); + dummyfd = fildes[1]; + add_unwind_protect (close, dummyfd); + +#if defined (JOB_CONTROL) + add_unwind_protect (restore_signal_mask, &oset); +#endif /* JOB_CONTROL */ + + if (ignore_return && cmd->value.Connection->first) + cmd->value.Connection->first->flags |= CMD_IGNORE_RETURN; + execute_command_internal (cmd->value.Connection->first, asynchronous, + prev, fildes[1], fd_bitmap); + + if (prev >= 0) + close (prev); + + prev = fildes[0]; + close (fildes[1]); + + dispose_fd_bitmap (fd_bitmap); + discard_unwind_frame ("pipe-file-descriptors"); + + cmd = cmd->value.Connection->second; + } + + lastpid = last_made_pid; + + /* Now execute the rightmost command in the pipeline. */ + if (ignore_return && cmd) + cmd->flags |= CMD_IGNORE_RETURN; + +#if defined (JOB_CONTROL) + lastpipe_flag = 0; + begin_unwind_frame ("lastpipe-exec"); + lstdin = -1; + /* If the `lastpipe' option is set with shopt, and job control is not + enabled, execute the last element of non-async pipelines in the + current shell environment. */ + if (lastpipe_opt && job_control == 0 && asynchronous == 0 && pipe_out == NO_PIPE && prev > 0) + { + lstdin = move_to_high_fd (0, 0, 255); + if (lstdin > 0) + { + do_piping (prev, pipe_out); + prev = NO_PIPE; + add_unwind_protect (restore_stdin, lstdin); + lastpipe_flag = 1; + freeze_jobs_list (); + lastpipe_jid = stop_pipeline (0, (COMMAND *)NULL); /* XXX */ + add_unwind_protect (lastpipe_cleanup, lastpipe_jid); + } + cmd->flags |= CMD_LASTPIPE; + } + if (prev >= 0) + add_unwind_protect (close, prev); +#endif + + exec_result = execute_command_internal (cmd, asynchronous, prev, pipe_out, fds_to_close); + +#if defined (JOB_CONTROL) + if (lstdin > 0) + restore_stdin (lstdin); +#endif + + if (prev >= 0) + close (prev); + +#if defined (JOB_CONTROL) + UNBLOCK_CHILD (oset); +#endif + + QUIT; + + if (lastpipe_flag) + { +#if defined (JOB_CONTROL) + append_process (savestring (the_printed_command), dollar_dollar_pid, exec_result, lastpipe_jid); +#endif + lstdin = wait_for (lastpid); +#if defined (JOB_CONTROL) + exec_result = job_exit_status (lastpipe_jid); +#endif + unfreeze_jobs_list (); + } + + discard_unwind_frame ("lastpipe-exec"); + + return (exec_result); +} + +static int +execute_connection (command, asynchronous, pipe_in, pipe_out, fds_to_close) + COMMAND *command; + int asynchronous, pipe_in, pipe_out; + struct fd_bitmap *fds_to_close; +{ + COMMAND *tc, *second; + int ignore_return, exec_result, was_error_trap, invert; + volatile int save_line_number; + + ignore_return = (command->flags & CMD_IGNORE_RETURN) != 0; + + switch (command->value.Connection->connector) + { + /* Do the first command asynchronously. */ + case '&': + tc = command->value.Connection->first; + if (tc == 0) + return (EXECUTION_SUCCESS); + + if (ignore_return) + tc->flags |= CMD_IGNORE_RETURN; + tc->flags |= CMD_AMPERSAND; + + /* If this shell was compiled without job control support, + if we are currently in a subshell via `( xxx )', or if job + control is not active then the standard input for an + asynchronous command is forced to /dev/null. */ +#if defined (JOB_CONTROL) + if ((subshell_environment || !job_control) && !stdin_redir) +#else + if (!stdin_redir) +#endif /* JOB_CONTROL */ + tc->flags |= CMD_STDIN_REDIR; + + exec_result = execute_command_internal (tc, 1, pipe_in, pipe_out, fds_to_close); + QUIT; + + if (tc->flags & CMD_STDIN_REDIR) + tc->flags &= ~CMD_STDIN_REDIR; + + second = command->value.Connection->second; + if (second) + { + if (ignore_return) + second->flags |= CMD_IGNORE_RETURN; + + exec_result = execute_command_internal (second, asynchronous, pipe_in, pipe_out, fds_to_close); + } + + break; + + /* Just call execute command on both sides. */ + case ';': + if (ignore_return) + { + if (command->value.Connection->first) + command->value.Connection->first->flags |= CMD_IGNORE_RETURN; + if (command->value.Connection->second) + command->value.Connection->second->flags |= CMD_IGNORE_RETURN; + } + executing_list++; + QUIT; + execute_command (command->value.Connection->first); + QUIT; + exec_result = execute_command_internal (command->value.Connection->second, + asynchronous, pipe_in, pipe_out, + fds_to_close); + executing_list--; + break; + + case '|': + was_error_trap = signal_is_trapped (ERROR_TRAP) && signal_is_ignored (ERROR_TRAP) == 0; + invert = (command->flags & CMD_INVERT_RETURN) != 0; + ignore_return = (command->flags & CMD_IGNORE_RETURN) != 0; + + line_number_for_err_trap = line_number; + exec_result = execute_pipeline (command, asynchronous, pipe_in, pipe_out, fds_to_close); + + if (was_error_trap && ignore_return == 0 && invert == 0 && exec_result != EXECUTION_SUCCESS) + { + last_command_exit_value = exec_result; + save_line_number = line_number; + line_number = line_number_for_err_trap; + run_error_trap (); + line_number = save_line_number; + } + + if (ignore_return == 0 && invert == 0 && exit_immediately_on_error && exec_result != EXECUTION_SUCCESS) + { + last_command_exit_value = exec_result; + run_pending_traps (); + jump_to_top_level (ERREXIT); + } + + break; + + case AND_AND: + case OR_OR: + if (asynchronous) + { + /* If we have something like `a && b &' or `a || b &', run the + && or || stuff in a subshell. Force a subshell and just call + execute_command_internal again. Leave asynchronous on + so that we get a report from the parent shell about the + background job. */ + command->flags |= CMD_FORCE_SUBSHELL; + exec_result = execute_command_internal (command, 1, pipe_in, pipe_out, fds_to_close); + break; + } + + /* Execute the first command. If the result of that is successful + and the connector is AND_AND, or the result is not successful + and the connector is OR_OR, then execute the second command, + otherwise return. */ + + executing_list++; + if (command->value.Connection->first) + command->value.Connection->first->flags |= CMD_IGNORE_RETURN; + + exec_result = execute_command (command->value.Connection->first); + QUIT; + if (((command->value.Connection->connector == AND_AND) && + (exec_result == EXECUTION_SUCCESS)) || + ((command->value.Connection->connector == OR_OR) && + (exec_result != EXECUTION_SUCCESS))) + { + if (ignore_return && command->value.Connection->second) + command->value.Connection->second->flags |= CMD_IGNORE_RETURN; + + exec_result = execute_command (command->value.Connection->second); + } + executing_list--; + break; + + default: + command_error ("execute_connection", CMDERR_BADCONN, command->value.Connection->connector, 0); + jump_to_top_level (DISCARD); + exec_result = EXECUTION_FAILURE; + } + + return exec_result; +} + +#define REAP() \ + do \ + { \ + if (!interactive_shell) \ + reap_dead_jobs (); \ + } \ + while (0) + +/* Execute a FOR command. The syntax is: FOR word_desc IN word_list; + DO command; DONE */ +static int +execute_for_command (for_command) + FOR_COM *for_command; +{ + register WORD_LIST *releaser, *list; + SHELL_VAR *v; + char *identifier; + int retval, save_line_number; +#if 0 + SHELL_VAR *old_value = (SHELL_VAR *)NULL; /* Remember the old value of x. */ +#endif + + save_line_number = line_number; + if (check_identifier (for_command->name, 1) == 0) + { + if (posixly_correct && interactive_shell == 0) + { + last_command_exit_value = EX_BADUSAGE; + jump_to_top_level (ERREXIT); + } + return (EXECUTION_FAILURE); + } + + loop_level++; + identifier = for_command->name->word; + + list = releaser = expand_words_no_vars (for_command->map_list); + + begin_unwind_frame ("for"); + add_unwind_protect (dispose_words, releaser); + +#if 0 + if (lexical_scoping) + { + old_value = copy_variable (find_variable (identifier)); + if (old_value) + add_unwind_protect (dispose_variable, old_value); + } +#endif + + if (for_command->flags & CMD_IGNORE_RETURN) + for_command->action->flags |= CMD_IGNORE_RETURN; + + for (retval = EXECUTION_SUCCESS; list; list = list->next) + { + QUIT; + + line_number = for_command->line; + + /* Remember what this command looks like, for debugger. */ + command_string_index = 0; + print_for_command_head (for_command); + + if (echo_command_at_execute) + xtrace_print_for_command_head (for_command); + + /* Save this command unless it's a trap command and we're not running + a debug trap. */ +#if 0 + if (signal_in_progress (DEBUG_TRAP) == 0 && (this_command_name == 0 || (STREQ (this_command_name, "trap") == 0))) +#else + if (signal_in_progress (DEBUG_TRAP) == 0 && running_trap == 0) +#endif + { + FREE (the_printed_command_except_trap); + the_printed_command_except_trap = savestring (the_printed_command); + } + + retval = run_debug_trap (); +#if defined (DEBUGGER) + /* In debugging mode, if the DEBUG trap returns a non-zero status, we + skip the command. */ + if (debugging_mode && retval != EXECUTION_SUCCESS) + continue; +#endif + + this_command_name = (char *)NULL; + v = bind_variable (identifier, list->word->word, 0); + if (readonly_p (v) || noassign_p (v)) + { + line_number = save_line_number; + if (readonly_p (v) && interactive_shell == 0 && posixly_correct) + { + last_command_exit_value = EXECUTION_FAILURE; + jump_to_top_level (FORCE_EOF); + } + else + { + dispose_words (releaser); + discard_unwind_frame ("for"); + loop_level--; + return (EXECUTION_FAILURE); + } + } + retval = execute_command (for_command->action); + REAP (); + QUIT; + + if (breaking) + { + breaking--; + break; + } + + if (continuing) + { + continuing--; + if (continuing) + break; + } + } + + loop_level--; + line_number = save_line_number; + +#if 0 + if (lexical_scoping) + { + if (!old_value) + unbind_variable (identifier); + else + { + SHELL_VAR *new_value; + + new_value = bind_variable (identifier, value_cell(old_value), 0); + new_value->attributes = old_value->attributes; + dispose_variable (old_value); + } + } +#endif + + dispose_words (releaser); + discard_unwind_frame ("for"); + return (retval); +} + +#if defined (ARITH_FOR_COMMAND) +/* Execute an arithmetic for command. The syntax is + + for (( init ; step ; test )) + do + body + done + + The execution should be exactly equivalent to + + eval \(\( init \)\) + while eval \(\( test \)\) ; do + body; + eval \(\( step \)\) + done +*/ +static intmax_t +eval_arith_for_expr (l, okp) + WORD_LIST *l; + int *okp; +{ + WORD_LIST *new; + intmax_t expresult; + int r; + + new = expand_words_no_vars (l); + if (new) + { + if (echo_command_at_execute) + xtrace_print_arith_cmd (new); + this_command_name = "(("; /* )) for expression error messages */ + + command_string_index = 0; + print_arith_command (new); + if (signal_in_progress (DEBUG_TRAP) == 0) + { + FREE (the_printed_command_except_trap); + the_printed_command_except_trap = savestring (the_printed_command); + } + + r = run_debug_trap (); + /* In debugging mode, if the DEBUG trap returns a non-zero status, we + skip the command. */ +#if defined (DEBUGGER) + if (debugging_mode == 0 || r == EXECUTION_SUCCESS) + expresult = evalexp (new->word->word, okp); + else + { + expresult = 0; + if (okp) + *okp = 1; + } +#else + expresult = evalexp (new->word->word, okp); +#endif + dispose_words (new); + } + else + { + expresult = 0; + if (okp) + *okp = 1; + } + return (expresult); +} + +static int +execute_arith_for_command (arith_for_command) + ARITH_FOR_COM *arith_for_command; +{ + intmax_t expresult; + int expok, body_status, arith_lineno, save_lineno; + + body_status = EXECUTION_SUCCESS; + loop_level++; + save_lineno = line_number; + + if (arith_for_command->flags & CMD_IGNORE_RETURN) + arith_for_command->action->flags |= CMD_IGNORE_RETURN; + + this_command_name = "(("; /* )) for expression error messages */ + + /* save the starting line number of the command so we can reset + line_number before executing each expression -- for $LINENO + and the DEBUG trap. */ + line_number = arith_lineno = arith_for_command->line; + if (variable_context && interactive_shell) + line_number -= function_line_number; + + /* Evaluate the initialization expression. */ + expresult = eval_arith_for_expr (arith_for_command->init, &expok); + if (expok == 0) + { + line_number = save_lineno; + return (EXECUTION_FAILURE); + } + + while (1) + { + /* Evaluate the test expression. */ + line_number = arith_lineno; + expresult = eval_arith_for_expr (arith_for_command->test, &expok); + line_number = save_lineno; + + if (expok == 0) + { + body_status = EXECUTION_FAILURE; + break; + } + REAP (); + if (expresult == 0) + break; + + /* Execute the body of the arithmetic for command. */ + QUIT; + body_status = execute_command (arith_for_command->action); + QUIT; + + /* Handle any `break' or `continue' commands executed by the body. */ + if (breaking) + { + breaking--; + break; + } + + if (continuing) + { + continuing--; + if (continuing) + break; + } + + /* Evaluate the step expression. */ + line_number = arith_lineno; + expresult = eval_arith_for_expr (arith_for_command->step, &expok); + line_number = save_lineno; + + if (expok == 0) + { + body_status = EXECUTION_FAILURE; + break; + } + } + + loop_level--; + line_number = save_lineno; + + return (body_status); +} +#endif + +#if defined (SELECT_COMMAND) +static int LINES, COLS, tabsize; + +#define RP_SPACE ") " +#define RP_SPACE_LEN 2 + +/* XXX - does not handle numbers > 1000000 at all. */ +#define NUMBER_LEN(s) \ +((s < 10) ? 1 \ + : ((s < 100) ? 2 \ + : ((s < 1000) ? 3 \ + : ((s < 10000) ? 4 \ + : ((s < 100000) ? 5 \ + : 6))))) + +static int +displen (s) + const char *s; +{ +#if defined (HANDLE_MULTIBYTE) + wchar_t *wcstr; + size_t wclen, slen; + + wcstr = 0; + slen = mbstowcs (wcstr, s, 0); + if (slen == -1) + slen = 0; + wcstr = (wchar_t *)xmalloc (sizeof (wchar_t) * (slen + 1)); + mbstowcs (wcstr, s, slen + 1); + wclen = wcswidth (wcstr, slen); + free (wcstr); + return ((int)wclen); +#else + return (STRLEN (s)); +#endif +} + +static int +print_index_and_element (len, ind, list) + int len, ind; + WORD_LIST *list; +{ + register WORD_LIST *l; + register int i; + + if (list == 0) + return (0); + for (i = ind, l = list; l && --i; l = l->next) + ; + fprintf (stderr, "%*d%s%s", len, ind, RP_SPACE, l->word->word); + return (displen (l->word->word)); +} + +static void +indent (from, to) + int from, to; +{ + while (from < to) + { + if ((to / tabsize) > (from / tabsize)) + { + putc ('\t', stderr); + from += tabsize - from % tabsize; + } + else + { + putc (' ', stderr); + from++; + } + } +} + +static void +print_select_list (list, list_len, max_elem_len, indices_len) + WORD_LIST *list; + int list_len, max_elem_len, indices_len; +{ + int ind, row, elem_len, pos, cols, rows; + int first_column_indices_len, other_indices_len; + + if (list == 0) + { + putc ('\n', stderr); + return; + } + + cols = max_elem_len ? COLS / max_elem_len : 1; + if (cols == 0) + cols = 1; + rows = list_len ? list_len / cols + (list_len % cols != 0) : 1; + cols = list_len ? list_len / rows + (list_len % rows != 0) : 1; + + if (rows == 1) + { + rows = cols; + cols = 1; + } + + first_column_indices_len = NUMBER_LEN (rows); + other_indices_len = indices_len; + + for (row = 0; row < rows; row++) + { + ind = row; + pos = 0; + while (1) + { + indices_len = (pos == 0) ? first_column_indices_len : other_indices_len; + elem_len = print_index_and_element (indices_len, ind + 1, list); + elem_len += indices_len + RP_SPACE_LEN; + ind += rows; + if (ind >= list_len) + break; + indent (pos + elem_len, pos + max_elem_len); + pos += max_elem_len; + } + putc ('\n', stderr); + } +} + +/* Print the elements of LIST, one per line, preceded by an index from 1 to + LIST_LEN. Then display PROMPT and wait for the user to enter a number. + If the number is between 1 and LIST_LEN, return that selection. If EOF + is read, return a null string. If a blank line is entered, or an invalid + number is entered, the loop is executed again. */ +static char * +select_query (list, list_len, prompt, print_menu) + WORD_LIST *list; + int list_len; + char *prompt; + int print_menu; +{ + int max_elem_len, indices_len, len; + intmax_t reply; + WORD_LIST *l; + char *repl_string, *t; + +#if 0 + t = get_string_value ("LINES"); + LINES = (t && *t) ? atoi (t) : 24; +#endif + t = get_string_value ("COLUMNS"); + COLS = (t && *t) ? atoi (t) : 80; + +#if 0 + t = get_string_value ("TABSIZE"); + tabsize = (t && *t) ? atoi (t) : 8; + if (tabsize <= 0) + tabsize = 8; +#else + tabsize = 8; +#endif + + max_elem_len = 0; + for (l = list; l; l = l->next) + { + len = displen (l->word->word); + if (len > max_elem_len) + max_elem_len = len; + } + indices_len = NUMBER_LEN (list_len); + max_elem_len += indices_len + RP_SPACE_LEN + 2; + + while (1) + { + if (print_menu) + print_select_list (list, list_len, max_elem_len, indices_len); + fprintf (stderr, "%s", prompt); + fflush (stderr); + QUIT; + + if (read_builtin ((WORD_LIST *)NULL) != EXECUTION_SUCCESS) + { + putchar ('\n'); + return ((char *)NULL); + } + repl_string = get_string_value ("REPLY"); + if (*repl_string == 0) + { + print_menu = 1; + continue; + } + if (legal_number (repl_string, &reply) == 0) + return ""; + if (reply < 1 || reply > list_len) + return ""; + + for (l = list; l && --reply; l = l->next) + ; + return (l->word->word); + } +} + +/* Execute a SELECT command. The syntax is: + SELECT word IN list DO command_list DONE + Only `break' or `return' in command_list will terminate + the command. */ +static int +execute_select_command (select_command) + SELECT_COM *select_command; +{ + WORD_LIST *releaser, *list; + SHELL_VAR *v; + char *identifier, *ps3_prompt, *selection; + int retval, list_len, show_menu, save_line_number; + + if (check_identifier (select_command->name, 1) == 0) + return (EXECUTION_FAILURE); + + save_line_number = line_number; + line_number = select_command->line; + + command_string_index = 0; + print_select_command_head (select_command); + + if (echo_command_at_execute) + xtrace_print_select_command_head (select_command); + +#if 0 + if (signal_in_progress (DEBUG_TRAP) == 0 && (this_command_name == 0 || (STREQ (this_command_name, "trap") == 0))) +#else + if (signal_in_progress (DEBUG_TRAP) == 0 && running_trap == 0) +#endif + { + FREE (the_printed_command_except_trap); + the_printed_command_except_trap = savestring (the_printed_command); + } + + retval = run_debug_trap (); +#if defined (DEBUGGER) + /* In debugging mode, if the DEBUG trap returns a non-zero status, we + skip the command. */ + if (debugging_mode && retval != EXECUTION_SUCCESS) + return (EXECUTION_SUCCESS); +#endif + + loop_level++; + identifier = select_command->name->word; + + /* command and arithmetic substitution, parameter and variable expansion, + word splitting, pathname expansion, and quote removal. */ + list = releaser = expand_words_no_vars (select_command->map_list); + list_len = list_length (list); + if (list == 0 || list_len == 0) + { + if (list) + dispose_words (list); + line_number = save_line_number; + return (EXECUTION_SUCCESS); + } + + begin_unwind_frame ("select"); + add_unwind_protect (dispose_words, releaser); + + if (select_command->flags & CMD_IGNORE_RETURN) + select_command->action->flags |= CMD_IGNORE_RETURN; + + retval = EXECUTION_SUCCESS; + show_menu = 1; + + while (1) + { + line_number = select_command->line; + ps3_prompt = get_string_value ("PS3"); + if (ps3_prompt == 0) + ps3_prompt = "#? "; + + QUIT; + selection = select_query (list, list_len, ps3_prompt, show_menu); + QUIT; + if (selection == 0) + { + /* select_query returns EXECUTION_FAILURE if the read builtin + fails, so we want to return failure in this case. */ + retval = EXECUTION_FAILURE; + break; + } + + v = bind_variable (identifier, selection, 0); + if (readonly_p (v) || noassign_p (v)) + { + if (readonly_p (v) && interactive_shell == 0 && posixly_correct) + { + last_command_exit_value = EXECUTION_FAILURE; + jump_to_top_level (FORCE_EOF); + } + else + { + dispose_words (releaser); + discard_unwind_frame ("select"); + loop_level--; + line_number = save_line_number; + return (EXECUTION_FAILURE); + } + } + + retval = execute_command (select_command->action); + + REAP (); + QUIT; + + if (breaking) + { + breaking--; + break; + } + + if (continuing) + { + continuing--; + if (continuing) + break; + } + +#if defined (KSH_COMPATIBLE_SELECT) + show_menu = 0; + selection = get_string_value ("REPLY"); + if (selection && *selection == '\0') + show_menu = 1; +#endif + } + + loop_level--; + line_number = save_line_number; + + dispose_words (releaser); + discard_unwind_frame ("select"); + return (retval); +} +#endif /* SELECT_COMMAND */ + +/* Execute a CASE command. The syntax is: CASE word_desc IN pattern_list ESAC. + The pattern_list is a linked list of pattern clauses; each clause contains + some patterns to compare word_desc against, and an associated command to + execute. */ +static int +execute_case_command (case_command) + CASE_COM *case_command; +{ + register WORD_LIST *list; + WORD_LIST *wlist, *es; + PATTERN_LIST *clauses; + char *word, *pattern; + int retval, match, ignore_return, save_line_number; + + save_line_number = line_number; + line_number = case_command->line; + + command_string_index = 0; + print_case_command_head (case_command); + + if (echo_command_at_execute) + xtrace_print_case_command_head (case_command); + +#if 0 + if (signal_in_progress (DEBUG_TRAP) == 0 && (this_command_name == 0 || (STREQ (this_command_name, "trap") == 0))) +#else + if (signal_in_progress (DEBUG_TRAP) == 0 && running_trap == 0) +#endif + { + FREE (the_printed_command_except_trap); + the_printed_command_except_trap = savestring (the_printed_command); + } + + retval = run_debug_trap(); +#if defined (DEBUGGER) + /* In debugging mode, if the DEBUG trap returns a non-zero status, we + skip the command. */ + if (debugging_mode && retval != EXECUTION_SUCCESS) + { + line_number = save_line_number; + return (EXECUTION_SUCCESS); + } +#endif + + wlist = expand_word_unsplit (case_command->word, 0); + word = wlist ? string_list (wlist) : savestring (""); + dispose_words (wlist); + + retval = EXECUTION_SUCCESS; + ignore_return = case_command->flags & CMD_IGNORE_RETURN; + + begin_unwind_frame ("case"); + add_unwind_protect ((Function *)xfree, word); + +#define EXIT_CASE() goto exit_case_command + + for (clauses = case_command->clauses; clauses; clauses = clauses->next) + { + QUIT; + for (list = clauses->patterns; list; list = list->next) + { + es = expand_word_leave_quoted (list->word, 0); + + if (es && es->word && es->word->word && *(es->word->word)) + pattern = quote_string_for_globbing (es->word->word, QGLOB_CVTNULL); + else + { + pattern = (char *)xmalloc (1); + pattern[0] = '\0'; + } + + /* Since the pattern does not undergo quote removal (as per + Posix.2, section 3.9.4.3), the strmatch () call must be able + to recognize backslashes as escape characters. */ + match = strmatch (pattern, word, FNMATCH_EXTFLAG|FNMATCH_IGNCASE) != FNM_NOMATCH; + free (pattern); + + dispose_words (es); + + if (match) + { + do + { + if (clauses->action && ignore_return) + clauses->action->flags |= CMD_IGNORE_RETURN; + retval = execute_command (clauses->action); + } + while ((clauses->flags & CASEPAT_FALLTHROUGH) && (clauses = clauses->next)); + if (clauses == 0 || (clauses->flags & CASEPAT_TESTNEXT) == 0) + EXIT_CASE (); + else + break; + } + + QUIT; + } + } + +exit_case_command: + free (word); + discard_unwind_frame ("case"); + line_number = save_line_number; + return (retval); +} + +#define CMD_WHILE 0 +#define CMD_UNTIL 1 + +/* The WHILE command. Syntax: WHILE test DO action; DONE. + Repeatedly execute action while executing test produces + EXECUTION_SUCCESS. */ +static int +execute_while_command (while_command) + WHILE_COM *while_command; +{ + return (execute_while_or_until (while_command, CMD_WHILE)); +} + +/* UNTIL is just like WHILE except that the test result is negated. */ +static int +execute_until_command (while_command) + WHILE_COM *while_command; +{ + return (execute_while_or_until (while_command, CMD_UNTIL)); +} + +/* The body for both while and until. The only difference between the + two is that the test value is treated differently. TYPE is + CMD_WHILE or CMD_UNTIL. The return value for both commands should + be EXECUTION_SUCCESS if no commands in the body are executed, and + the status of the last command executed in the body otherwise. */ +static int +execute_while_or_until (while_command, type) + WHILE_COM *while_command; + int type; +{ + int return_value, body_status; + + body_status = EXECUTION_SUCCESS; + loop_level++; + + while_command->test->flags |= CMD_IGNORE_RETURN; + if (while_command->flags & CMD_IGNORE_RETURN) + while_command->action->flags |= CMD_IGNORE_RETURN; + + while (1) + { + return_value = execute_command (while_command->test); + REAP (); + + /* Need to handle `break' in the test when we would break out of the + loop. The job control code will set `breaking' to loop_level + when a job in a loop is stopped with SIGTSTP. If the stopped job + is in the loop test, `breaking' will not be reset unless we do + this, and the shell will cease to execute commands. */ + if (type == CMD_WHILE && return_value != EXECUTION_SUCCESS) + { + if (breaking) + breaking--; + break; + } + if (type == CMD_UNTIL && return_value == EXECUTION_SUCCESS) + { + if (breaking) + breaking--; + break; + } + + QUIT; + body_status = execute_command (while_command->action); + QUIT; + + if (breaking) + { + breaking--; + break; + } + + if (continuing) + { + continuing--; + if (continuing) + break; + } + } + loop_level--; + + return (body_status); +} + +/* IF test THEN command [ELSE command]. + IF also allows ELIF in the place of ELSE IF, but + the parser makes *that* stupidity transparent. */ +static int +execute_if_command (if_command) + IF_COM *if_command; +{ + int return_value, save_line_number; + + save_line_number = line_number; + if_command->test->flags |= CMD_IGNORE_RETURN; + return_value = execute_command (if_command->test); + line_number = save_line_number; + + if (return_value == EXECUTION_SUCCESS) + { + QUIT; + + if (if_command->true_case && (if_command->flags & CMD_IGNORE_RETURN)) + if_command->true_case->flags |= CMD_IGNORE_RETURN; + + return (execute_command (if_command->true_case)); + } + else + { + QUIT; + + if (if_command->false_case && (if_command->flags & CMD_IGNORE_RETURN)) + if_command->false_case->flags |= CMD_IGNORE_RETURN; + + return (execute_command (if_command->false_case)); + } +} + +#if defined (DPAREN_ARITHMETIC) +static int +execute_arith_command (arith_command) + ARITH_COM *arith_command; +{ + int expok, save_line_number, retval; + intmax_t expresult; + WORD_LIST *new; + char *exp; + + expresult = 0; + + save_line_number = line_number; + this_command_name = "(("; /* )) */ + line_number = arith_command->line; + /* If we're in a function, update the line number information. */ + if (variable_context && interactive_shell) + line_number -= function_line_number; + + command_string_index = 0; + print_arith_command (arith_command->exp); + + if (signal_in_progress (DEBUG_TRAP) == 0) + { + FREE (the_printed_command_except_trap); + the_printed_command_except_trap = savestring (the_printed_command); + } + + /* Run the debug trap before each arithmetic command, but do it after we + update the line number information and before we expand the various + words in the expression. */ + retval = run_debug_trap (); +#if defined (DEBUGGER) + /* In debugging mode, if the DEBUG trap returns a non-zero status, we + skip the command. */ + if (debugging_mode && retval != EXECUTION_SUCCESS) + { + line_number = save_line_number; + return (EXECUTION_SUCCESS); + } +#endif + + new = expand_words_no_vars (arith_command->exp); + + /* If we're tracing, make a new word list with `((' at the front and `))' + at the back and print it. */ + if (echo_command_at_execute) + xtrace_print_arith_cmd (new); + + if (new) + { + exp = new->next ? string_list (new) : new->word->word; + expresult = evalexp (exp, &expok); + line_number = save_line_number; + if (exp != new->word->word) + free (exp); + dispose_words (new); + } + else + { + expresult = 0; + expok = 1; + } + + if (expok == 0) + return (EXECUTION_FAILURE); + + return (expresult == 0 ? EXECUTION_FAILURE : EXECUTION_SUCCESS); +} +#endif /* DPAREN_ARITHMETIC */ + +#if defined (COND_COMMAND) + +static char * const nullstr = ""; + +static int +execute_cond_node (cond) + COND_COM *cond; +{ + int result, invert, patmatch, rmatch, mflags, ignore; + char *arg1, *arg2; + + invert = (cond->flags & CMD_INVERT_RETURN); + ignore = (cond->flags & CMD_IGNORE_RETURN); + if (ignore) + { + if (cond->left) + cond->left->flags |= CMD_IGNORE_RETURN; + if (cond->right) + cond->right->flags |= CMD_IGNORE_RETURN; + } + + if (cond->type == COND_EXPR) + result = execute_cond_node (cond->left); + else if (cond->type == COND_OR) + { + result = execute_cond_node (cond->left); + if (result != EXECUTION_SUCCESS) + result = execute_cond_node (cond->right); + } + else if (cond->type == COND_AND) + { + result = execute_cond_node (cond->left); + if (result == EXECUTION_SUCCESS) + result = execute_cond_node (cond->right); + } + else if (cond->type == COND_UNARY) + { + if (ignore) + comsub_ignore_return++; + arg1 = cond_expand_word (cond->left->op, 0); + if (ignore) + comsub_ignore_return--; + if (arg1 == 0) + arg1 = nullstr; + if (echo_command_at_execute) + xtrace_print_cond_term (cond->type, invert, cond->op, arg1, (char *)NULL); + result = unary_test (cond->op->word, arg1) ? EXECUTION_SUCCESS : EXECUTION_FAILURE; + if (arg1 != nullstr) + free (arg1); + } + else if (cond->type == COND_BINARY) + { + rmatch = 0; + patmatch = ((cond->op->word[1] == '=') && (cond->op->word[2] == '\0') && + (cond->op->word[0] == '!' || cond->op->word[0] == '=') || + (cond->op->word[0] == '=' && cond->op->word[1] == '\0')); +#if defined (COND_REGEXP) + rmatch = (cond->op->word[0] == '=' && cond->op->word[1] == '~' && + cond->op->word[2] == '\0'); +#endif + + if (ignore) + comsub_ignore_return++; + arg1 = cond_expand_word (cond->left->op, 0); + if (ignore) + comsub_ignore_return--; + if (arg1 == 0) + arg1 = nullstr; + if (ignore) + comsub_ignore_return++; + arg2 = cond_expand_word (cond->right->op, + (rmatch && shell_compatibility_level > 31) ? 2 : (patmatch ? 1 : 0)); + if (ignore) + comsub_ignore_return--; + if (arg2 == 0) + arg2 = nullstr; + + if (echo_command_at_execute) + xtrace_print_cond_term (cond->type, invert, cond->op, arg1, arg2); + +#if defined (COND_REGEXP) + if (rmatch) + { + mflags = SHMAT_PWARN; +#if defined (ARRAY_VARS) + mflags |= SHMAT_SUBEXP; +#endif + + result = sh_regmatch (arg1, arg2, mflags); + } + else +#endif /* COND_REGEXP */ + { + int oe; + oe = extended_glob; + extended_glob = 1; + result = binary_test (cond->op->word, arg1, arg2, TEST_PATMATCH|TEST_ARITHEXP|TEST_LOCALE) + ? EXECUTION_SUCCESS + : EXECUTION_FAILURE; + extended_glob = oe; + } + if (arg1 != nullstr) + free (arg1); + if (arg2 != nullstr) + free (arg2); + } + else + { + command_error ("execute_cond_node", CMDERR_BADTYPE, cond->type, 0); + jump_to_top_level (DISCARD); + result = EXECUTION_FAILURE; + } + + if (invert) + result = (result == EXECUTION_SUCCESS) ? EXECUTION_FAILURE : EXECUTION_SUCCESS; + + return result; +} + +static int +execute_cond_command (cond_command) + COND_COM *cond_command; +{ + int retval, save_line_number; + + retval = EXECUTION_SUCCESS; + save_line_number = line_number; + + this_command_name = "[["; + line_number = cond_command->line; + /* If we're in a function, update the line number information. */ + if (variable_context && interactive_shell) + line_number -= function_line_number; + command_string_index = 0; + print_cond_command (cond_command); + + if (signal_in_progress (DEBUG_TRAP) == 0) + { + FREE (the_printed_command_except_trap); + the_printed_command_except_trap = savestring (the_printed_command); + } + + /* Run the debug trap before each conditional command, but do it after we + update the line number information. */ + retval = run_debug_trap (); +#if defined (DEBUGGER) + /* In debugging mode, if the DEBUG trap returns a non-zero status, we + skip the command. */ + if (debugging_mode && retval != EXECUTION_SUCCESS) + { + line_number = save_line_number; + return (EXECUTION_SUCCESS); + } +#endif + +#if 0 + debug_print_cond_command (cond_command); +#endif + + last_command_exit_value = retval = execute_cond_node (cond_command); + line_number = save_line_number; + return (retval); +} +#endif /* COND_COMMAND */ + +static void +bind_lastarg (arg) + char *arg; +{ + SHELL_VAR *var; + + if (arg == 0) + arg = ""; + var = bind_variable ("_", arg, 0); + VUNSETATTR (var, att_exported); +} + +/* Execute a null command. Fork a subshell if the command uses pipes or is + to be run asynchronously. This handles all the side effects that are + supposed to take place. */ +static int +execute_null_command (redirects, pipe_in, pipe_out, async) + REDIRECT *redirects; + int pipe_in, pipe_out, async; +{ + int r; + int forcefork; + REDIRECT *rd; + + for (forcefork = 0, rd = redirects; rd; rd = rd->next) + forcefork += rd->rflags & REDIR_VARASSIGN; + + if (forcefork || pipe_in != NO_PIPE || pipe_out != NO_PIPE || async) + { + /* We have a null command, but we really want a subshell to take + care of it. Just fork, do piping and redirections, and exit. */ + if (make_child ((char *)NULL, async) == 0) + { + /* Cancel traps, in trap.c. */ + restore_original_signals (); /* XXX */ + + do_piping (pipe_in, pipe_out); + +#if defined (COPROCESS_SUPPORT) + coproc_closeall (); +#endif + + subshell_environment = 0; + if (async) + subshell_environment |= SUBSHELL_ASYNC; + if (pipe_in != NO_PIPE || pipe_out != NO_PIPE) + subshell_environment |= SUBSHELL_PIPE; + + if (do_redirections (redirects, RX_ACTIVE) == 0) + exit (EXECUTION_SUCCESS); + else + exit (EXECUTION_FAILURE); + } + else + { + close_pipes (pipe_in, pipe_out); +#if defined (PROCESS_SUBSTITUTION) && defined (HAVE_DEV_FD) + unlink_fifo_list (); +#endif + return (EXECUTION_SUCCESS); + } + } + else + { + /* Even if there aren't any command names, pretend to do the + redirections that are specified. The user expects the side + effects to take place. If the redirections fail, then return + failure. Otherwise, if a command substitution took place while + expanding the command or a redirection, return the value of that + substitution. Otherwise, return EXECUTION_SUCCESS. */ + + r = do_redirections (redirects, RX_ACTIVE|RX_UNDOABLE); + cleanup_redirects (redirection_undo_list); + redirection_undo_list = (REDIRECT *)NULL; + + if (r != 0) + return (EXECUTION_FAILURE); + else if (last_command_subst_pid != NO_PID) + return (last_command_exit_value); + else + return (EXECUTION_SUCCESS); + } +} + +/* This is a hack to suppress word splitting for assignment statements + given as arguments to builtins with the ASSIGNMENT_BUILTIN flag set. */ +static void +fix_assignment_words (words) + WORD_LIST *words; +{ + WORD_LIST *w, *wcmd; + struct builtin *b; + int assoc; + + if (words == 0) + return; + + b = 0; + assoc = 0; + + wcmd = words; + for (w = words; w; w = w->next) + if (w->word->flags & W_ASSIGNMENT) + { + if (b == 0) + { + while (posixly_correct && wcmd && wcmd->word && wcmd->word->word && STREQ (wcmd->word->word, "command")) + wcmd = wcmd->next; + b = builtin_address_internal (wcmd->word->word, 0); + if (b == 0 || (b->flags & ASSIGNMENT_BUILTIN) == 0) + return; + else if (b && (b->flags & ASSIGNMENT_BUILTIN)) + wcmd->word->flags |= W_ASSNBLTIN; + } + w->word->flags |= (W_NOSPLIT|W_NOGLOB|W_TILDEEXP|W_ASSIGNARG); +#if defined (ARRAY_VARS) + if (assoc) + w->word->flags |= W_ASSIGNASSOC; +#endif + } +#if defined (ARRAY_VARS) + /* Note that we saw an associative array option to a builtin that takes + assignment statements. This is a bit of a kludge. */ + else if (w->word->word[0] == '-' && strchr (w->word->word, 'A')) + { + if (b == 0) + { + b = builtin_address_internal (wcmd->word->word, 0); + if (b == 0 || (b->flags & ASSIGNMENT_BUILTIN) == 0) + return; + else if (b && (b->flags & ASSIGNMENT_BUILTIN)) + wcmd->word->flags |= W_ASSNBLTIN; + } + if (wcmd->word->flags & W_ASSNBLTIN) + assoc = 1; + } +#endif +} + +/* Return 1 if the file found by searching $PATH for PATHNAME, defaulting + to PATHNAME, is a directory. Used by the autocd code below. */ +static int +is_dirname (pathname) + char *pathname; +{ + char *temp; + temp = search_for_command (pathname); + return (temp ? file_isdir (temp) : file_isdir (pathname)); +} + +/* The meaty part of all the executions. We have to start hacking the + real execution of commands here. Fork a process, set things up, + execute the command. */ +static int +execute_simple_command (simple_command, pipe_in, pipe_out, async, fds_to_close) + SIMPLE_COM *simple_command; + int pipe_in, pipe_out, async; + struct fd_bitmap *fds_to_close; +{ + WORD_LIST *words, *lastword; + char *command_line, *lastarg, *temp; + int first_word_quoted, result, builtin_is_special, already_forked, dofork; + pid_t old_last_async_pid; + sh_builtin_func_t *builtin; + SHELL_VAR *func; + volatile int old_builtin, old_command_builtin; + + result = EXECUTION_SUCCESS; + special_builtin_failed = builtin_is_special = 0; + command_line = (char *)0; + + QUIT; + + /* If we're in a function, update the line number information. */ + if (variable_context && interactive_shell && sourcelevel == 0) + line_number -= function_line_number; + + /* Remember what this command line looks like at invocation. */ + command_string_index = 0; + print_simple_command (simple_command); + +#if 0 + if (signal_in_progress (DEBUG_TRAP) == 0 && (this_command_name == 0 || (STREQ (this_command_name, "trap") == 0))) +#else + if (signal_in_progress (DEBUG_TRAP) == 0 && running_trap == 0) +#endif + { + FREE (the_printed_command_except_trap); + the_printed_command_except_trap = the_printed_command ? savestring (the_printed_command) : (char *)0; + } + + /* Run the debug trap before each simple command, but do it after we + update the line number information. */ + result = run_debug_trap (); +#if defined (DEBUGGER) + /* In debugging mode, if the DEBUG trap returns a non-zero status, we + skip the command. */ + if (debugging_mode && result != EXECUTION_SUCCESS) + return (EXECUTION_SUCCESS); +#endif + + first_word_quoted = + simple_command->words ? (simple_command->words->word->flags & W_QUOTED) : 0; + + last_command_subst_pid = NO_PID; + old_last_async_pid = last_asynchronous_pid; + + already_forked = dofork = 0; + + /* If we're in a pipeline or run in the background, set DOFORK so we + make the child early, before word expansion. This keeps assignment + statements from affecting the parent shell's environment when they + should not. */ + dofork = pipe_in != NO_PIPE || pipe_out != NO_PIPE || async; + + /* Something like `%2 &' should restart job 2 in the background, not cause + the shell to fork here. */ + if (dofork && pipe_in == NO_PIPE && pipe_out == NO_PIPE && + simple_command->words && simple_command->words->word && + simple_command->words->word->word && + (simple_command->words->word->word[0] == '%')) + dofork = 0; + + if (dofork) + { + /* Do this now, because execute_disk_command will do it anyway in the + vast majority of cases. */ + maybe_make_export_env (); + + /* Don't let a DEBUG trap overwrite the command string to be saved with + the process/job associated with this child. */ + if (make_child (savestring (the_printed_command_except_trap), async) == 0) + { + already_forked = 1; + simple_command->flags |= CMD_NO_FORK; + + subshell_environment = SUBSHELL_FORK; + if (pipe_in != NO_PIPE || pipe_out != NO_PIPE) + subshell_environment |= SUBSHELL_PIPE; + if (async) + subshell_environment |= SUBSHELL_ASYNC; + + /* We need to do this before piping to handle some really + pathological cases where one of the pipe file descriptors + is < 2. */ + if (fds_to_close) + close_fd_bitmap (fds_to_close); + + do_piping (pipe_in, pipe_out); + pipe_in = pipe_out = NO_PIPE; +#if defined (COPROCESS_SUPPORT) + coproc_closeall (); +#endif + + last_asynchronous_pid = old_last_async_pid; + } + else + { + /* Don't let simple commands that aren't the last command in a + pipeline change $? for the rest of the pipeline (or at all). */ + if (pipe_out != NO_PIPE) + result = last_command_exit_value; + close_pipes (pipe_in, pipe_out); +#if defined (PROCESS_SUBSTITUTION) && defined (HAVE_DEV_FD) + unlink_fifo_list (); +#endif + command_line = (char *)NULL; /* don't free this. */ + bind_lastarg ((char *)NULL); + return (result); + } + } + + /* If we are re-running this as the result of executing the `command' + builtin, do not expand the command words a second time. */ + if ((simple_command->flags & CMD_INHIBIT_EXPANSION) == 0) + { + current_fds_to_close = fds_to_close; + fix_assignment_words (simple_command->words); + /* Pass the ignore return flag down to command substitutions */ + if (simple_command->flags & CMD_IGNORE_RETURN) /* XXX */ + comsub_ignore_return++; + words = expand_words (simple_command->words); + if (simple_command->flags & CMD_IGNORE_RETURN) + comsub_ignore_return--; + current_fds_to_close = (struct fd_bitmap *)NULL; + } + else + words = copy_word_list (simple_command->words); + + /* It is possible for WORDS not to have anything left in it. + Perhaps all the words consisted of `$foo', and there was + no variable `$foo'. */ + if (words == 0) + { + this_command_name = 0; + result = execute_null_command (simple_command->redirects, + pipe_in, pipe_out, + already_forked ? 0 : async); + if (already_forked) + exit (result); + else + { + bind_lastarg ((char *)NULL); + set_pipestatus_from_exit (result); + return (result); + } + } + + lastarg = (char *)NULL; + + begin_unwind_frame ("simple-command"); + + if (echo_command_at_execute) + xtrace_print_word_list (words, 1); + + builtin = (sh_builtin_func_t *)NULL; + func = (SHELL_VAR *)NULL; + if ((simple_command->flags & CMD_NO_FUNCTIONS) == 0) + { + /* Posix.2 says special builtins are found before functions. We + don't set builtin_is_special anywhere other than here, because + this path is followed only when the `command' builtin is *not* + being used, and we don't want to exit the shell if a special + builtin executed with `command builtin' fails. `command' is not + a special builtin. */ + if (posixly_correct) + { + builtin = find_special_builtin (words->word->word); + if (builtin) + builtin_is_special = 1; + } + if (builtin == 0) + func = find_function (words->word->word); + } + + /* In POSIX mode, assignment errors in the temporary environment cause a + non-interactive shell to exit. */ + if (builtin_is_special && interactive_shell == 0 && tempenv_assign_error) + { + last_command_exit_value = EXECUTION_FAILURE; + jump_to_top_level (ERREXIT); + } + + add_unwind_protect (dispose_words, words); + QUIT; + + /* Bind the last word in this command to "$_" after execution. */ + for (lastword = words; lastword->next; lastword = lastword->next) + ; + lastarg = lastword->word->word; + +#if defined (JOB_CONTROL) + /* Is this command a job control related thing? */ + if (words->word->word[0] == '%' && already_forked == 0) + { + this_command_name = async ? "bg" : "fg"; + last_shell_builtin = this_shell_builtin; + this_shell_builtin = builtin_address (this_command_name); + result = (*this_shell_builtin) (words); + goto return_result; + } + + /* One other possiblilty. The user may want to resume an existing job. + If they do, find out whether this word is a candidate for a running + job. */ + if (job_control && already_forked == 0 && async == 0 && + !first_word_quoted && + !words->next && + words->word->word[0] && + !simple_command->redirects && + pipe_in == NO_PIPE && + pipe_out == NO_PIPE && + (temp = get_string_value ("auto_resume"))) + { + int job, jflags, started_status; + + jflags = JM_STOPPED|JM_FIRSTMATCH; + if (STREQ (temp, "exact")) + jflags |= JM_EXACT; + else if (STREQ (temp, "substring")) + jflags |= JM_SUBSTRING; + else + jflags |= JM_PREFIX; + job = get_job_by_name (words->word->word, jflags); + if (job != NO_JOB) + { + run_unwind_frame ("simple-command"); + this_command_name = "fg"; + last_shell_builtin = this_shell_builtin; + this_shell_builtin = builtin_address ("fg"); + + started_status = start_job (job, 1); + return ((started_status < 0) ? EXECUTION_FAILURE : started_status); + } + } +#endif /* JOB_CONTROL */ + +run_builtin: + /* Remember the name of this command globally. */ + this_command_name = words->word->word; + + QUIT; + + /* This command could be a shell builtin or a user-defined function. + We have already found special builtins by this time, so we do not + set builtin_is_special. If this is a function or builtin, and we + have pipes, then fork a subshell in here. Otherwise, just execute + the command directly. */ + if (func == 0 && builtin == 0) + builtin = find_shell_builtin (this_command_name); + + last_shell_builtin = this_shell_builtin; + this_shell_builtin = builtin; + + if (builtin || func) + { + if (builtin) + { + old_builtin = executing_builtin; + old_command_builtin = executing_command_builtin; + unwind_protect_int (executing_builtin); /* modified in execute_builtin */ + unwind_protect_int (executing_command_builtin); /* ditto */ + } + if (already_forked) + { + /* reset_terminating_signals (); */ /* XXX */ + /* Reset the signal handlers in the child, but don't free the + trap strings. Set a flag noting that we have to free the + trap strings if we run trap to change a signal disposition. */ + reset_signal_handlers (); + subshell_environment |= SUBSHELL_RESETTRAP; + + if (async) + { + if ((simple_command->flags & CMD_STDIN_REDIR) && + pipe_in == NO_PIPE && + (stdin_redirects (simple_command->redirects) == 0)) + async_redirect_stdin (); + setup_async_signals (); + } + + subshell_level++; + execute_subshell_builtin_or_function + (words, simple_command->redirects, builtin, func, + pipe_in, pipe_out, async, fds_to_close, + simple_command->flags); + subshell_level--; + } + else + { + result = execute_builtin_or_function + (words, builtin, func, simple_command->redirects, fds_to_close, + simple_command->flags); + if (builtin) + { + if (result > EX_SHERRBASE) + { + result = builtin_status (result); + if (builtin_is_special) + special_builtin_failed = 1; + } + /* In POSIX mode, if there are assignment statements preceding + a special builtin, they persist after the builtin + completes. */ + if (posixly_correct && builtin_is_special && temporary_env) + merge_temporary_env (); + } + else /* function */ + { + if (result == EX_USAGE) + result = EX_BADUSAGE; + else if (result > EX_SHERRBASE) + result = EXECUTION_FAILURE; + } + + set_pipestatus_from_exit (result); + + goto return_result; + } + } + + if (autocd && interactive && words->word && is_dirname (words->word->word)) + { + words = make_word_list (make_word ("cd"), words); + xtrace_print_word_list (words, 0); + goto 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 + + result = execute_disk_command (words, simple_command->redirects, command_line, + pipe_in, pipe_out, async, fds_to_close, + simple_command->flags); + + return_result: + bind_lastarg (lastarg); + FREE (command_line); + dispose_words (words); + if (builtin) + { + executing_builtin = old_builtin; + executing_command_builtin = old_command_builtin; + } + discard_unwind_frame ("simple-command"); + this_command_name = (char *)NULL; /* points to freed memory now */ + return (result); +} + +/* Translate the special builtin exit statuses. We don't really need a + function for this; it's a placeholder for future work. */ +static int +builtin_status (result) + int result; +{ + int r; + + switch (result) + { + case EX_USAGE: + r = EX_BADUSAGE; + break; + case EX_REDIRFAIL: + case EX_BADSYNTAX: + case EX_BADASSIGN: + case EX_EXPFAIL: + r = EXECUTION_FAILURE; + break; + default: + r = EXECUTION_SUCCESS; + break; + } + return (r); +} + +static int +execute_builtin (builtin, words, flags, subshell) + sh_builtin_func_t *builtin; + WORD_LIST *words; + int flags, subshell; +{ + int old_e_flag, result, eval_unwind; + int isbltinenv; + char *error_trap; + + error_trap = 0; + old_e_flag = exit_immediately_on_error; + /* The eval builtin calls parse_and_execute, which does not know about + the setting of flags, and always calls the execution functions with + flags that will exit the shell on an error if -e is set. If the + eval builtin is being called, and we're supposed to ignore the exit + value of the command, we turn the -e flag off ourselves and disable + the ERR trap, then restore them when the command completes. This is + also a problem (as below) for the command and source/. builtins. */ + if (subshell == 0 && (flags & CMD_IGNORE_RETURN) && + (builtin == eval_builtin || builtin == command_builtin || builtin == source_builtin)) + { + begin_unwind_frame ("eval_builtin"); + unwind_protect_int (exit_immediately_on_error); + error_trap = TRAP_STRING (ERROR_TRAP); + if (error_trap) + { + error_trap = savestring (error_trap); + add_unwind_protect (xfree, error_trap); + add_unwind_protect (set_error_trap, error_trap); + restore_default_signal (ERROR_TRAP); + } + exit_immediately_on_error = 0; + eval_unwind = 1; + } + else + eval_unwind = 0; + + /* The temporary environment for a builtin is supposed to apply to + all commands executed by that builtin. Currently, this is a + problem only with the `unset', `source' and `eval' builtins. */ + + isbltinenv = (builtin == source_builtin || builtin == eval_builtin || builtin == unset_builtin); + + if (isbltinenv) + { + if (subshell == 0) + begin_unwind_frame ("builtin_env"); + + if (temporary_env) + { + push_scope (VC_BLTNENV, temporary_env); + if (subshell == 0) + add_unwind_protect (pop_scope, (flags & CMD_COMMAND_BUILTIN) ? 0 : "1"); + temporary_env = (HASH_TABLE *)NULL; + } + } + + /* `return' does a longjmp() back to a saved environment in execute_function. + If a variable assignment list preceded the command, and the shell is + running in POSIX mode, we need to merge that into the shell_variables + table, since `return' is a POSIX special builtin. */ + if (posixly_correct && subshell == 0 && builtin == return_builtin && temporary_env) + { + begin_unwind_frame ("return_temp_env"); + add_unwind_protect (merge_temporary_env, (char *)NULL); + } + + executing_builtin++; + executing_command_builtin |= builtin == command_builtin; + result = ((*builtin) (words->next)); + + /* This shouldn't happen, but in case `return' comes back instead of + longjmp'ing, we need to unwind. */ + if (posixly_correct && subshell == 0 && builtin == return_builtin && temporary_env) + discard_unwind_frame ("return_temp_env"); + + if (subshell == 0 && isbltinenv) + run_unwind_frame ("builtin_env"); + + if (eval_unwind) + { + exit_immediately_on_error += old_e_flag; + if (error_trap) + { + set_error_trap (error_trap); + xfree (error_trap); + } + discard_unwind_frame ("eval_builtin"); + } + + return (result); +} + +static int +execute_function (var, words, flags, fds_to_close, async, subshell) + SHELL_VAR *var; + WORD_LIST *words; + int flags; + struct fd_bitmap *fds_to_close; + int async, subshell; +{ + int return_val, result; + COMMAND *tc, *fc, *save_current; + char *debug_trap, *error_trap, *return_trap; +#if defined (ARRAY_VARS) + SHELL_VAR *funcname_v, *nfv, *bash_source_v, *bash_lineno_v; + ARRAY *funcname_a; + volatile ARRAY *bash_source_a; + volatile ARRAY *bash_lineno_a; +#endif + FUNCTION_DEF *shell_fn; + char *sfile, *t; + + USE_VAR(fc); + + if (funcnest_max > 0 && funcnest >= funcnest_max) + { + internal_error ("%s: maximum function nesting level exceeded (%d)", var->name, funcnest); + funcnest = 0; /* XXX - should we reset it somewhere else? */ + jump_to_top_level (DISCARD); + } + +#if defined (ARRAY_VARS) + GET_ARRAY_FROM_VAR ("FUNCNAME", funcname_v, funcname_a); + GET_ARRAY_FROM_VAR ("BASH_SOURCE", bash_source_v, bash_source_a); + GET_ARRAY_FROM_VAR ("BASH_LINENO", bash_lineno_v, bash_lineno_a); +#endif + + tc = (COMMAND *)copy_command (function_cell (var)); + if (tc && (flags & CMD_IGNORE_RETURN)) + tc->flags |= CMD_IGNORE_RETURN; + + if (subshell == 0) + { + begin_unwind_frame ("function_calling"); + push_context (var->name, subshell, temporary_env); + add_unwind_protect (pop_context, (char *)NULL); + unwind_protect_int (line_number); + unwind_protect_int (return_catch_flag); + unwind_protect_jmp_buf (return_catch); + add_unwind_protect (dispose_command, (char *)tc); + unwind_protect_pointer (this_shell_function); + unwind_protect_int (loop_level); + unwind_protect_int (funcnest); + } + else + push_context (var->name, subshell, temporary_env); /* don't unwind-protect for subshells */ + + temporary_env = (HASH_TABLE *)NULL; + + this_shell_function = var; + make_funcname_visible (1); + + debug_trap = TRAP_STRING(DEBUG_TRAP); + error_trap = TRAP_STRING(ERROR_TRAP); + return_trap = TRAP_STRING(RETURN_TRAP); + + /* The order of the unwind protects for debug_trap, error_trap and + return_trap is important here! unwind-protect commands are run + in reverse order of registration. If this causes problems, take + out the xfree unwind-protect calls and live with the small memory leak. */ + + /* function_trace_mode != 0 means that all functions inherit the DEBUG trap. + if the function has the trace attribute set, it inherits the DEBUG trap */ + if (debug_trap && ((trace_p (var) == 0) && function_trace_mode == 0)) + { + if (subshell == 0) + { + debug_trap = savestring (debug_trap); + add_unwind_protect (xfree, debug_trap); + add_unwind_protect (set_debug_trap, debug_trap); + } + restore_default_signal (DEBUG_TRAP); + } + + /* error_trace_mode != 0 means that functions inherit the ERR trap. */ + if (error_trap && error_trace_mode == 0) + { + if (subshell == 0) + { + error_trap = savestring (error_trap); + add_unwind_protect (xfree, error_trap); + add_unwind_protect (set_error_trap, error_trap); + } + restore_default_signal (ERROR_TRAP); + } + + /* Shell functions inherit the RETURN trap if function tracing is on + globally or on individually for this function. */ +#if 0 + if (return_trap && ((trace_p (var) == 0) && function_trace_mode == 0)) +#else + if (return_trap && (signal_in_progress (DEBUG_TRAP) || ((trace_p (var) == 0) && function_trace_mode == 0))) +#endif + { + if (subshell == 0) + { + return_trap = savestring (return_trap); + add_unwind_protect (xfree, return_trap); + add_unwind_protect (set_return_trap, return_trap); + } + restore_default_signal (RETURN_TRAP); + } + + funcnest++; +#if defined (ARRAY_VARS) + /* This is quite similar to the code in shell.c and elsewhere. */ + shell_fn = find_function_def (this_shell_function->name); + sfile = shell_fn ? shell_fn->source_file : ""; + array_push ((ARRAY *)funcname_a, this_shell_function->name); + + array_push ((ARRAY *)bash_source_a, sfile); + t = itos (executing_line_number ()); + array_push ((ARRAY *)bash_lineno_a, t); + free (t); +#endif + + /* The temporary environment for a function is supposed to apply to + all commands executed within the function body. */ + + remember_args (words->next, 1); + + /* Update BASH_ARGV and BASH_ARGC */ + if (debugging_mode) + push_args (words->next); + + /* Number of the line on which the function body starts. */ + line_number = function_line_number = tc->line; + +#if defined (JOB_CONTROL) + if (subshell) + stop_pipeline (async, (COMMAND *)NULL); +#endif + + fc = tc; + + return_catch_flag++; + return_val = setjmp (return_catch); + + if (return_val) + { + result = return_catch_value; + /* Run the RETURN trap in the function's context. */ + save_current = currently_executing_command; + run_return_trap (); + currently_executing_command = save_current; + } + else + { + /* Run the debug trap here so we can trap at the start of a function's + execution rather than the execution of the body's first command. */ + showing_function_line = 1; + save_current = currently_executing_command; + result = run_debug_trap (); +#if defined (DEBUGGER) + /* In debugging mode, if the DEBUG trap returns a non-zero status, we + skip the command. */ + if (debugging_mode == 0 || result == EXECUTION_SUCCESS) + { + showing_function_line = 0; + currently_executing_command = save_current; + result = execute_command_internal (fc, 0, NO_PIPE, NO_PIPE, fds_to_close); + + /* Run the RETURN trap in the function's context */ + save_current = currently_executing_command; + run_return_trap (); + currently_executing_command = save_current; + } +#else + result = execute_command_internal (fc, 0, NO_PIPE, NO_PIPE, fds_to_close); + + save_current = currently_executing_command; + run_return_trap (); + currently_executing_command = save_current; +#endif + showing_function_line = 0; + } + + /* Restore BASH_ARGC and BASH_ARGV */ + if (debugging_mode) + pop_args (); + + if (subshell == 0) + run_unwind_frame ("function_calling"); + +#if defined (ARRAY_VARS) + /* These two variables cannot be unset, and cannot be affected by the + function. */ + array_pop ((ARRAY *)bash_source_a); + array_pop ((ARRAY *)bash_lineno_a); + + /* FUNCNAME can be unset, and so can potentially be changed by the + function. */ + GET_ARRAY_FROM_VAR ("FUNCNAME", nfv, funcname_a); + if (nfv == funcname_v) + array_pop (funcname_a); +#endif + + if (variable_context == 0 || this_shell_function == 0) + { + make_funcname_visible (0); +#if defined (PROCESS_SUBSTITUTION) + unlink_fifo_list (); +#endif + } + + return (result); +} + +/* A convenience routine for use by other parts of the shell to execute + a particular shell function. */ +int +execute_shell_function (var, words) + SHELL_VAR *var; + WORD_LIST *words; +{ + int ret; + struct fd_bitmap *bitmap; + + bitmap = new_fd_bitmap (FD_BITMAP_DEFAULT_SIZE); + begin_unwind_frame ("execute-shell-function"); + add_unwind_protect (dispose_fd_bitmap, (char *)bitmap); + + ret = execute_function (var, words, 0, bitmap, 0, 0); + + dispose_fd_bitmap (bitmap); + discard_unwind_frame ("execute-shell-function"); + + return ret; +} + +/* Execute a shell builtin or function in a subshell environment. This + routine does not return; it only calls exit(). If BUILTIN is non-null, + it points to a function to call to execute a shell builtin; otherwise + VAR points at the body of a function to execute. WORDS is the arguments + to the command, REDIRECTS specifies redirections to perform before the + command is executed. */ +static void +execute_subshell_builtin_or_function (words, redirects, builtin, var, + pipe_in, pipe_out, async, fds_to_close, + flags) + WORD_LIST *words; + REDIRECT *redirects; + sh_builtin_func_t *builtin; + SHELL_VAR *var; + int pipe_in, pipe_out, async; + struct fd_bitmap *fds_to_close; + int flags; +{ + int result, r, funcvalue; +#if defined (JOB_CONTROL) + int jobs_hack; + + jobs_hack = (builtin == jobs_builtin) && + ((subshell_environment & SUBSHELL_ASYNC) == 0 || pipe_out != NO_PIPE); +#endif + + /* A subshell is neither a login shell nor interactive. */ + login_shell = interactive = 0; + + if (async) + subshell_environment |= SUBSHELL_ASYNC; + if (pipe_in != NO_PIPE || pipe_out != NO_PIPE) + subshell_environment |= SUBSHELL_PIPE; + + maybe_make_export_env (); /* XXX - is this needed? */ + +#if defined (JOB_CONTROL) + /* Eradicate all traces of job control after we fork the subshell, so + all jobs begun by this subshell are in the same process group as + the shell itself. */ + + /* Allow the output of `jobs' to be piped. */ + if (jobs_hack) + kill_current_pipeline (); + else + without_job_control (); + + set_sigchld_handler (); +#endif /* JOB_CONTROL */ + + set_sigint_handler (); + + if (fds_to_close) + close_fd_bitmap (fds_to_close); + + do_piping (pipe_in, pipe_out); + + if (do_redirections (redirects, RX_ACTIVE) != 0) + exit (EXECUTION_FAILURE); + + if (builtin) + { + /* Give builtins a place to jump back to on failure, + so we don't go back up to main(). */ + result = setjmp (top_level); + + /* Give the return builtin a place to jump to when executed in a subshell + or pipeline */ + funcvalue = 0; + if (return_catch_flag && builtin == return_builtin) + funcvalue = setjmp (return_catch); + + if (result == EXITPROG) + exit (last_command_exit_value); + else if (result) + exit (EXECUTION_FAILURE); + else if (funcvalue) + exit (return_catch_value); + else + { + r = execute_builtin (builtin, words, flags, 1); + fflush (stdout); + if (r == EX_USAGE) + r = EX_BADUSAGE; + exit (r); + } + } + else + { + r = execute_function (var, words, flags, fds_to_close, async, 1); + fflush (stdout); + exit (r); + } +} + +/* Execute a builtin or function in the current shell context. If BUILTIN + is non-null, it is the builtin command to execute, otherwise VAR points + to the body of a function. WORDS are the command's arguments, REDIRECTS + are the redirections to perform. FDS_TO_CLOSE is the usual bitmap of + file descriptors to close. + + If BUILTIN is exec_builtin, the redirections specified in REDIRECTS are + not undone before this function returns. */ +static int +execute_builtin_or_function (words, builtin, var, redirects, + fds_to_close, flags) + WORD_LIST *words; + sh_builtin_func_t *builtin; + SHELL_VAR *var; + REDIRECT *redirects; + struct fd_bitmap *fds_to_close; + int flags; +{ + int result; + REDIRECT *saved_undo_list; +#if defined (PROCESS_SUBSTITUTION) + int ofifo, nfifo, osize; + char *ofifo_list; +#endif + + +#if defined (PROCESS_SUBSTITUTION) + ofifo = num_fifos (); + ofifo_list = copy_fifo_list (&osize); +#endif + + if (do_redirections (redirects, RX_ACTIVE|RX_UNDOABLE) != 0) + { + cleanup_redirects (redirection_undo_list); + redirection_undo_list = (REDIRECT *)NULL; + dispose_exec_redirects (); +#if defined (PROCESS_SUBSTITUTION) + free (ofifo_list); +#endif + return (EX_REDIRFAIL); /* was EXECUTION_FAILURE */ + } + + saved_undo_list = redirection_undo_list; + + /* Calling the "exec" builtin changes redirections forever. */ + if (builtin == exec_builtin) + { + dispose_redirects (saved_undo_list); + saved_undo_list = exec_redirection_undo_list; + exec_redirection_undo_list = (REDIRECT *)NULL; + } + else + dispose_exec_redirects (); + + if (saved_undo_list) + { + begin_unwind_frame ("saved redirects"); + add_unwind_protect (cleanup_redirects, (char *)saved_undo_list); + } + + redirection_undo_list = (REDIRECT *)NULL; + + if (builtin) + result = execute_builtin (builtin, words, flags, 0); + else + result = execute_function (var, words, flags, fds_to_close, 0, 0); + + /* We do this before undoing the effects of any redirections. */ + fflush (stdout); + fpurge (stdout); + if (ferror (stdout)) + clearerr (stdout); + + /* If we are executing the `command' builtin, but this_shell_builtin is + set to `exec_builtin', we know that we have something like + `command exec [redirection]', since otherwise `exec' would have + overwritten the shell and we wouldn't get here. In this case, we + want to behave as if the `command' builtin had not been specified + and preserve the redirections. */ + if (builtin == command_builtin && this_shell_builtin == exec_builtin) + { + int discard; + + discard = 0; + if (saved_undo_list) + { + dispose_redirects (saved_undo_list); + discard = 1; + } + redirection_undo_list = exec_redirection_undo_list; + saved_undo_list = exec_redirection_undo_list = (REDIRECT *)NULL; + if (discard) + discard_unwind_frame ("saved redirects"); + } + + if (saved_undo_list) + { + redirection_undo_list = saved_undo_list; + discard_unwind_frame ("saved redirects"); + } + + if (redirection_undo_list) + { + cleanup_redirects (redirection_undo_list); + redirection_undo_list = (REDIRECT *)NULL; + } + +#if defined (PROCESS_SUBSTITUTION) + /* Close any FIFOs created by this builtin or function. */ + nfifo = num_fifos (); + if (nfifo > ofifo) + close_new_fifos (ofifo_list, osize); + free (ofifo_list); +#endif + + return (result); +} + +void +setup_async_signals () +{ +#if defined (__BEOS__) + set_signal_handler (SIGHUP, SIG_IGN); /* they want csh-like behavior */ +#endif + +#if defined (JOB_CONTROL) + if (job_control == 0) +#endif + { + set_signal_handler (SIGINT, SIG_IGN); + set_signal_ignored (SIGINT); + set_signal_handler (SIGQUIT, SIG_IGN); + set_signal_ignored (SIGQUIT); + } +} + +/* Execute a simple command that is hopefully defined in a disk file + somewhere. + + 1) fork () + 2) connect pipes + 3) look up the command + 4) do redirections + 5) execve () + 6) If the execve failed, see if the file has executable mode set. + If so, and it isn't a directory, then execute its contents as + a shell script. + + Note that the filename hashing stuff has to take place up here, + in the parent. This is probably why the Bourne style shells + don't handle it, since that would require them to go through + this gnarly hair, for no good reason. + + NOTE: callers expect this to fork or exit(). */ + +/* Name of a shell function to call when a command name is not found. */ +#ifndef NOTFOUND_HOOK +# define NOTFOUND_HOOK "command_not_found_handle" +#endif + +static int +execute_disk_command (words, redirects, command_line, pipe_in, pipe_out, + async, fds_to_close, cmdflags) + WORD_LIST *words; + REDIRECT *redirects; + char *command_line; + int pipe_in, pipe_out, async; + struct fd_bitmap *fds_to_close; + int cmdflags; +{ + char *pathname, *command, **args; + int nofork, result; + pid_t pid; + SHELL_VAR *hookf; + WORD_LIST *wl; + + nofork = (cmdflags & CMD_NO_FORK); /* Don't fork, just exec, if no pipes */ + pathname = words->word->word; + + result = EXECUTION_SUCCESS; +#if defined (RESTRICTED_SHELL) + command = (char *)NULL; + if (restricted && mbschr (pathname, '/')) + { + internal_error (_("%s: restricted: cannot specify `/' in command names"), + pathname); + result = last_command_exit_value = EXECUTION_FAILURE; + + /* If we're not going to fork below, we must already be in a child + process or a context in which it's safe to call exit(2). */ + if (nofork && pipe_in == NO_PIPE && pipe_out == NO_PIPE) + exit (last_command_exit_value); + else + goto parent_return; + } +#endif /* RESTRICTED_SHELL */ + + command = search_for_command (pathname); + + if (command) + { + maybe_make_export_env (); + put_command_name_into_env (command); + } + + /* We have to make the child before we check for the non-existence + of COMMAND, since we want the error messages to be redirected. */ + /* If we can get away without forking and there are no pipes to deal with, + don't bother to fork, just directly exec the command. */ + if (nofork && pipe_in == NO_PIPE && pipe_out == NO_PIPE) + pid = 0; + else + pid = make_child (savestring (command_line), async); + + if (pid == 0) + { + int old_interactive; + +#if 0 + /* This has been disabled for the time being. */ +#if !defined (ARG_MAX) || ARG_MAX >= 10240 + if (posixly_correct == 0) + put_gnu_argv_flags_into_env ((long)getpid (), glob_argv_flags); +#endif +#endif + + reset_terminating_signals (); /* XXX */ + /* Cancel traps, in trap.c. */ + restore_original_signals (); + + /* restore_original_signals may have undone the work done + by make_child to ensure that SIGINT and SIGQUIT are ignored + in asynchronous children. */ + if (async) + { + if ((cmdflags & CMD_STDIN_REDIR) && + pipe_in == NO_PIPE && + (stdin_redirects (redirects) == 0)) + async_redirect_stdin (); + setup_async_signals (); + } + + /* This functionality is now provided by close-on-exec of the + file descriptors manipulated by redirection and piping. + Some file descriptors still need to be closed in all children + because of the way bash does pipes; fds_to_close is a + bitmap of all such file descriptors. */ + if (fds_to_close) + close_fd_bitmap (fds_to_close); + + do_piping (pipe_in, pipe_out); + + old_interactive = interactive; + if (async) + interactive = 0; + + subshell_environment = SUBSHELL_FORK; + + if (redirects && (do_redirections (redirects, RX_ACTIVE) != 0)) + { +#if defined (PROCESS_SUBSTITUTION) + /* Try to remove named pipes that may have been created as the + result of redirections. */ + unlink_fifo_list (); +#endif /* PROCESS_SUBSTITUTION */ + exit (EXECUTION_FAILURE); + } + + if (async) + interactive = old_interactive; + + if (command == 0) + { + hookf = find_function (NOTFOUND_HOOK); + if (hookf == 0) + { + /* Make sure filenames are displayed using printable characters */ + if (ansic_shouldquote (pathname)) + pathname = ansic_quote (pathname, 0, NULL); + internal_error (_("%s: command not found"), pathname); + exit (EX_NOTFOUND); /* Posix.2 says the exit status is 127 */ + } + + wl = make_word_list (make_word (NOTFOUND_HOOK), words); + exit (execute_shell_function (hookf, wl)); + } + + /* Execve expects the command name to be in args[0]. So we + leave it there, in the same format that the user used to + type it in. */ + args = strvec_from_word_list (words, 0, 0, (int *)NULL); + exit (shell_execve (command, args, export_env)); + } + else + { +parent_return: + QUIT; + + /* Make sure that the pipes are closed in the parent. */ + close_pipes (pipe_in, pipe_out); +#if defined (PROCESS_SUBSTITUTION) && defined (HAVE_DEV_FD) + if (variable_context == 0) + unlink_fifo_list (); +#endif + FREE (command); + return (result); + } +} + +/* CPP defines to decide whether a particular index into the #! line + corresponds to a valid interpreter name or argument character, or + whitespace. The MSDOS define is to allow \r to be treated the same + as \n. */ + +#if !defined (MSDOS) +# define STRINGCHAR(ind) \ + (ind < sample_len && !whitespace (sample[ind]) && sample[ind] != '\n') +# define WHITECHAR(ind) \ + (ind < sample_len && whitespace (sample[ind])) +#else /* MSDOS */ +# define STRINGCHAR(ind) \ + (ind < sample_len && !whitespace (sample[ind]) && sample[ind] != '\n' && sample[ind] != '\r') +# define WHITECHAR(ind) \ + (ind < sample_len && whitespace (sample[ind])) +#endif /* MSDOS */ + +static char * +getinterp (sample, sample_len, endp) + char *sample; + int sample_len, *endp; +{ + register int i; + char *execname; + int start; + + /* Find the name of the interpreter to exec. */ + for (i = 2; i < sample_len && whitespace (sample[i]); i++) + ; + + for (start = i; STRINGCHAR(i); i++) + ; + + execname = substring (sample, start, i); + + if (endp) + *endp = i; + return execname; +} + +#if !defined (HAVE_HASH_BANG_EXEC) +/* If the operating system on which we're running does not handle + the #! executable format, then help out. SAMPLE is the text read + from the file, SAMPLE_LEN characters. COMMAND is the name of + the script; it and ARGS, the arguments given by the user, will + become arguments to the specified interpreter. ENV is the environment + to pass to the interpreter. + + The word immediately following the #! is the interpreter to execute. + A single argument to the interpreter is allowed. */ + +static int +execute_shell_script (sample, sample_len, command, args, env) + char *sample; + int sample_len; + char *command; + char **args, **env; +{ + char *execname, *firstarg; + int i, start, size_increment, larry; + + /* Find the name of the interpreter to exec. */ + execname = getinterp (sample, sample_len, &i); + size_increment = 1; + + /* Now the argument, if any. */ + for (firstarg = (char *)NULL, start = i; WHITECHAR(i); i++) + ; + + /* If there is more text on the line, then it is an argument for the + interpreter. */ + + if (STRINGCHAR(i)) + { + for (start = i; STRINGCHAR(i); i++) + ; + firstarg = substring ((char *)sample, start, i); + size_increment = 2; + } + + larry = strvec_len (args) + size_increment; + args = strvec_resize (args, larry + 1); + + for (i = larry - 1; i; i--) + args[i] = args[i - size_increment]; + + args[0] = execname; + if (firstarg) + { + args[1] = firstarg; + args[2] = command; + } + else + args[1] = command; + + args[larry] = (char *)NULL; + + return (shell_execve (execname, args, env)); +} +#undef STRINGCHAR +#undef WHITECHAR + +#endif /* !HAVE_HASH_BANG_EXEC */ + +static void +initialize_subshell () +{ +#if defined (ALIAS) + /* Forget about any aliases that we knew of. We are in a subshell. */ + delete_all_aliases (); +#endif /* ALIAS */ + +#if defined (HISTORY) + /* Forget about the history lines we have read. This is a non-interactive + subshell. */ + history_lines_this_session = 0; +#endif + +#if defined (JOB_CONTROL) + /* Forget about the way job control was working. We are in a subshell. */ + without_job_control (); + set_sigchld_handler (); + init_job_stats (); +#endif /* JOB_CONTROL */ + + /* Reset the values of the shell flags and options. */ + reset_shell_flags (); + reset_shell_options (); + reset_shopt_options (); + + /* Zero out builtin_env, since this could be a shell script run from a + sourced file with a temporary environment supplied to the `source/.' + builtin. Such variables are not supposed to be exported (empirical + testing with sh and ksh). Just throw it away; don't worry about a + memory leak. */ + if (vc_isbltnenv (shell_variables)) + shell_variables = shell_variables->down; + + clear_unwind_protect_list (0); + /* XXX -- are there other things we should be resetting here? */ + parse_and_execute_level = 0; /* nothing left to restore it */ + + /* We're no longer inside a shell function. */ + variable_context = return_catch_flag = funcnest = 0; + + executing_list = 0; /* XXX */ + + /* If we're not interactive, close the file descriptor from which we're + reading the current shell script. */ + if (interactive_shell == 0) + unset_bash_input (0); +} + +#if defined (HAVE_SETOSTYPE) && defined (_POSIX_SOURCE) +# define SETOSTYPE(x) __setostype(x) +#else +# define SETOSTYPE(x) +#endif + +#define READ_SAMPLE_BUF(file, buf, len) \ + do \ + { \ + fd = open(file, O_RDONLY); \ + if (fd >= 0) \ + { \ + len = read (fd, buf, 80); \ + close (fd); \ + } \ + else \ + len = -1; \ + } \ + while (0) + +/* Call execve (), handling interpreting shell scripts, and handling + exec failures. */ +int +shell_execve (command, args, env) + char *command; + char **args, **env; +{ + int larray, i, fd; + char sample[80]; + int sample_len; + + SETOSTYPE (0); /* Some systems use for USG/POSIX semantics */ + execve (command, args, env); + i = errno; /* error from execve() */ + CHECK_TERMSIG; + SETOSTYPE (1); + + /* If we get to this point, then start checking out the file. + Maybe it is something we can hack ourselves. */ + if (i != ENOEXEC) + { + if (file_isdir (command)) +#if defined (EISDIR) + internal_error (_("%s: %s"), command, strerror (EISDIR)); +#else + internal_error (_("%s: is a directory"), command); +#endif + else if (executable_file (command) == 0) + { + errno = i; + file_error (command); + } + /* errors not involving the path argument to execve. */ + else if (i == E2BIG || i == ENOMEM) + { + errno = i; + file_error (command); + } + else + { + /* The file has the execute bits set, but the kernel refuses to + run it for some reason. See why. */ +#if defined (HAVE_HASH_BANG_EXEC) + READ_SAMPLE_BUF (command, sample, sample_len); + if (sample_len > 2 && sample[0] == '#' && sample[1] == '!') + { + char *interp; + int ilen; + + interp = getinterp (sample, sample_len, (int *)NULL); + ilen = strlen (interp); + errno = i; + if (interp[ilen - 1] == '\r') + { + interp = xrealloc (interp, ilen + 2); + interp[ilen - 1] = '^'; + interp[ilen] = 'M'; + interp[ilen + 1] = '\0'; + } + sys_error (_("%s: %s: bad interpreter"), command, interp ? interp : ""); + FREE (interp); + return (EX_NOEXEC); + } +#endif + errno = i; + file_error (command); + } + return ((i == ENOENT) ? EX_NOTFOUND : EX_NOEXEC); /* XXX Posix.2 says that exit status is 126 */ + } + + /* This file is executable. + If it begins with #!, then help out people with losing operating + systems. Otherwise, check to see if it is a binary file by seeing + if the contents of the first line (or up to 80 characters) are in the + ASCII set. If it's a text file, execute the contents as shell commands, + otherwise return 126 (EX_BINARY_FILE). */ + READ_SAMPLE_BUF (command, sample, sample_len); + + if (sample_len == 0) + return (EXECUTION_SUCCESS); + + /* Is this supposed to be an executable script? + If so, the format of the line is "#! interpreter [argument]". + A single argument is allowed. The BSD kernel restricts + the length of the entire line to 32 characters (32 bytes + being the size of the BSD exec header), but we allow 80 + characters. */ + if (sample_len > 0) + { +#if !defined (HAVE_HASH_BANG_EXEC) + if (sample_len > 2 && sample[0] == '#' && sample[1] == '!') + return (execute_shell_script (sample, sample_len, command, args, env)); + else +#endif + if (check_binary_file (sample, sample_len)) + { + internal_error (_("%s: cannot execute binary file"), command); + return (EX_BINARY_FILE); + } + } + + /* We have committed to attempting to execute the contents of this file + as shell commands. */ + + initialize_subshell (); + + set_sigint_handler (); + + /* Insert the name of this shell into the argument list. */ + larray = strvec_len (args) + 1; + args = strvec_resize (args, larray + 1); + + for (i = larray - 1; i; i--) + args[i] = args[i - 1]; + + args[0] = shell_name; + args[1] = command; + args[larray] = (char *)NULL; + + if (args[0][0] == '-') + args[0]++; + +#if defined (RESTRICTED_SHELL) + if (restricted) + change_flag ('r', FLAG_OFF); +#endif + + if (subshell_argv) + { + /* Can't free subshell_argv[0]; that is shell_name. */ + for (i = 1; i < subshell_argc; i++) + free (subshell_argv[i]); + free (subshell_argv); + } + + dispose_command (currently_executing_command); /* XXX */ + currently_executing_command = (COMMAND *)NULL; + + subshell_argc = larray; + subshell_argv = args; + subshell_envp = env; + + unbind_args (); /* remove the positional parameters */ + + longjmp (subshell_top_level, 1); + /*NOTREACHED*/ +} + +static int +execute_intern_function (name, function) + WORD_DESC *name; + COMMAND *function; +{ + SHELL_VAR *var; + + if (check_identifier (name, posixly_correct) == 0) + { + if (posixly_correct && interactive_shell == 0) + { + last_command_exit_value = EX_BADUSAGE; + jump_to_top_level (ERREXIT); + } + return (EXECUTION_FAILURE); + } + + var = find_function (name->word); + if (var && (readonly_p (var) || noassign_p (var))) + { + if (readonly_p (var)) + internal_error (_("%s: readonly function"), var->name); + return (EXECUTION_FAILURE); + } + + bind_function (name->word, function); + return (EXECUTION_SUCCESS); +} + +#if defined (INCLUDE_UNUSED) +#if defined (PROCESS_SUBSTITUTION) +void +close_all_files () +{ + register int i, fd_table_size; + + fd_table_size = getdtablesize (); + if (fd_table_size > 256) /* clamp to a reasonable value */ + fd_table_size = 256; + + for (i = 3; i < fd_table_size; i++) + close (i); +} +#endif /* PROCESS_SUBSTITUTION */ +#endif + +static void +close_pipes (in, out) + int in, out; +{ + if (in >= 0) + close (in); + if (out >= 0) + close (out); +} + +static void +dup_error (oldd, newd) + int oldd, newd; +{ + sys_error (_("cannot duplicate fd %d to fd %d"), oldd, newd); +} + +/* Redirect input and output to be from and to the specified pipes. + NO_PIPE and REDIRECT_BOTH are handled correctly. */ +static void +do_piping (pipe_in, pipe_out) + int pipe_in, pipe_out; +{ + if (pipe_in != NO_PIPE) + { + if (dup2 (pipe_in, 0) < 0) + dup_error (pipe_in, 0); + if (pipe_in > 0) + close (pipe_in); +#ifdef __CYGWIN__ + /* Let stdio know the fd may have changed from text to binary mode. */ + freopen (NULL, "r", stdin); +#endif /* __CYGWIN__ */ + } + if (pipe_out != NO_PIPE) + { + if (pipe_out != REDIRECT_BOTH) + { + if (dup2 (pipe_out, 1) < 0) + dup_error (pipe_out, 1); + if (pipe_out == 0 || pipe_out > 1) + close (pipe_out); + } + else + { + if (dup2 (1, 2) < 0) + dup_error (1, 2); + } +#ifdef __CYGWIN__ + /* Let stdio know the fd may have changed from text to binary mode, and + make sure to preserve stdout line buffering. */ + freopen (NULL, "w", stdout); + sh_setlinebuf (stdout); +#endif /* __CYGWIN__ */ + } +} diff --git a/expr.c b/expr.c index f7329c39e..b1dddede7 100644 --- a/expr.c +++ b/expr.c @@ -480,19 +480,23 @@ expassign () if (special) { + if ((op == DIV || op == MOD) && value == 0) + { + if (noeval == 0) + evalerror (_("division by 0")); + else + value = 1; + } + switch (op) { case MUL: lvalue *= value; break; case DIV: - if (value == 0) - evalerror (_("division by 0")); lvalue /= value; break; case MOD: - if (value == 0) - evalerror (_("division by 0")); lvalue %= value; break; case PLUS: @@ -808,7 +812,12 @@ exp2 () val2 = exppower (); if (((op == DIV) || (op == MOD)) && (val2 == 0)) - evalerror (_("division by 0")); + { + if (noeval == 0) + evalerror (_("division by 0")); + else + val2 = 1; + } if (op == MUL) val1 *= val2; diff --git a/expr.c~ b/expr.c~ new file mode 100644 index 000000000..a42918f28 --- /dev/null +++ b/expr.c~ @@ -0,0 +1,1473 @@ +/* expr.c -- arithmetic expression evaluation. */ + +/* Copyright (C) 1990-2010 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 3 of the License, 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. If not, see . +*/ + +/* + All arithmetic is done as intmax_t integers with no checking for overflow + (though division by 0 is caught and flagged as an error). + + The following operators are handled, grouped into a set of levels in + order of decreasing precedence. + + "id++", "id--" [post-increment and post-decrement] + "++id", "--id" [pre-increment and pre-decrement] + "-", "+" [(unary operators)] + "!", "~" + "**" [(exponentiation)] + "*", "/", "%" + "+", "-" + "<<", ">>" + "<=", ">=", "<", ">" + "==", "!=" + "&" + "^" + "|" + "&&" + "||" + "expr ? expr : expr" + "=", "*=", "/=", "%=", "+=", "-=", "<<=", ">>=", "&=", "^=", "|=" + , [comma] + + (Note that most of these operators have special meaning to bash, and an + entire expression should be quoted, e.g. "a=$a+1" or "a=a+1" to ensure + that it is passed intact to the evaluator when using `let'. When using + the $[] or $(( )) forms, the text between the `[' and `]' or `((' and `))' + is treated as if in double quotes.) + + Sub-expressions within parentheses have a precedence level greater than + all of the above levels and are evaluated first. Within a single prece- + dence group, evaluation is left-to-right, except for the arithmetic + assignment operator (`='), which is evaluated right-to-left (as in C). + + The expression evaluator returns the value of the expression (assignment + statements have as a value what is returned by the RHS). The `let' + builtin, on the other hand, returns 0 if the last expression evaluates to + a non-zero, and 1 otherwise. + + Implementation is a recursive-descent parser. + + Chet Ramey + chet@ins.CWRU.Edu +*/ + +#include "config.h" + +#include +#include "bashansi.h" + +#if defined (HAVE_UNISTD_H) +# ifdef _MINIX +# include +# endif +# include +#endif + +#include "chartypes.h" +#include "bashintl.h" + +#include "shell.h" + +/* Because of the $((...)) construct, expressions may include newlines. + Here is a macro which accepts newlines, tabs and spaces as whitespace. */ +#define cr_whitespace(c) (whitespace(c) || ((c) == '\n')) + +/* Size be which the expression stack grows when neccessary. */ +#define EXPR_STACK_GROW_SIZE 10 + +/* Maximum amount of recursion allowed. This prevents a non-integer + variable such as "num=num+2" from infinitely adding to itself when + "let num=num+2" is given. */ +#define MAX_EXPR_RECURSION_LEVEL 1024 + +/* The Tokens. Singing "The Lion Sleeps Tonight". */ + +#define EQEQ 1 /* "==" */ +#define NEQ 2 /* "!=" */ +#define LEQ 3 /* "<=" */ +#define GEQ 4 /* ">=" */ +#define STR 5 /* string */ +#define NUM 6 /* number */ +#define LAND 7 /* "&&" Logical AND */ +#define LOR 8 /* "||" Logical OR */ +#define LSH 9 /* "<<" Left SHift */ +#define RSH 10 /* ">>" Right SHift */ +#define OP_ASSIGN 11 /* op= expassign as in Posix.2 */ +#define COND 12 /* exp1 ? exp2 : exp3 */ +#define POWER 13 /* exp1**exp2 */ +#define PREINC 14 /* ++var */ +#define PREDEC 15 /* --var */ +#define POSTINC 16 /* var++ */ +#define POSTDEC 17 /* var-- */ +#define EQ '=' +#define GT '>' +#define LT '<' +#define PLUS '+' +#define MINUS '-' +#define MUL '*' +#define DIV '/' +#define MOD '%' +#define NOT '!' +#define LPAR '(' +#define RPAR ')' +#define BAND '&' /* Bitwise AND */ +#define BOR '|' /* Bitwise OR. */ +#define BXOR '^' /* Bitwise eXclusive OR. */ +#define BNOT '~' /* Bitwise NOT; Two's complement. */ +#define QUES '?' +#define COL ':' +#define COMMA ',' + +/* This should be the function corresponding to the operator with the + highest precedence. */ +#define EXP_HIGHEST expcomma + +#ifndef MAX_INT_LEN +# define MAX_INT_LEN 32 +#endif + +struct lvalue +{ + char *tokstr; /* possibly-rewritten lvalue if not NULL */ + intmax_t tokval; /* expression evaluated value */ + SHELL_VAR *tokvar; /* variable described by array or var reference */ + intmax_t ind; /* array index if not -1 */ +}; + +/* A structure defining a single expression context. */ +typedef struct { + int curtok, lasttok; + char *expression, *tp, *lasttp; + intmax_t tokval; + char *tokstr; + int noeval; + struct lvalue lval; +} EXPR_CONTEXT; + +static char *expression; /* The current expression */ +static char *tp; /* token lexical position */ +static char *lasttp; /* pointer to last token position */ +static int curtok; /* the current token */ +static int lasttok; /* the previous token */ +static int assigntok; /* the OP in OP= */ +static char *tokstr; /* current token string */ +static intmax_t tokval; /* current token value */ +static int noeval; /* set to 1 if no assignment to be done */ +static procenv_t evalbuf; + +static struct lvalue curlval = {0, 0, 0, -1}; +static struct lvalue lastlval = {0, 0, 0, -1}; + +static int _is_arithop __P((int)); +static void readtok __P((void)); /* lexical analyzer */ + +static void init_lvalue __P((struct lvalue *)); +static struct lvalue *alloc_lvalue __P((void)); +static void free_lvalue __P((struct lvalue *)); + +static intmax_t expr_streval __P((char *, int, struct lvalue *)); +static intmax_t strlong __P((char *)); +static void evalerror __P((const char *)); + +static void pushexp __P((void)); +static void popexp __P((void)); +static void expr_unwind __P((void)); +static void expr_bind_variable __P((char *, char *)); +static void expr_bind_array_element __P((char *, arrayind_t, char *)); + +static intmax_t subexpr __P((char *)); + +static intmax_t expcomma __P((void)); +static intmax_t expassign __P((void)); +static intmax_t expcond __P((void)); +static intmax_t explor __P((void)); +static intmax_t expland __P((void)); +static intmax_t expbor __P((void)); +static intmax_t expbxor __P((void)); +static intmax_t expband __P((void)); +static intmax_t exp5 __P((void)); +static intmax_t exp4 __P((void)); +static intmax_t expshift __P((void)); +static intmax_t exp3 __P((void)); +static intmax_t exp2 __P((void)); +static intmax_t exppower __P((void)); +static intmax_t exp1 __P((void)); +static intmax_t exp0 __P((void)); + +/* Global var which contains the stack of expression contexts. */ +static EXPR_CONTEXT **expr_stack; +static int expr_depth; /* Location in the stack. */ +static int expr_stack_size; /* Number of slots already allocated. */ + +extern char *this_command_name; +extern int unbound_vars_is_error, last_command_exit_value; + +#if defined (ARRAY_VARS) +extern const char * const bash_badsub_errmsg; +#endif + +#define SAVETOK(X) \ + do { \ + (X)->curtok = curtok; \ + (X)->lasttok = lasttok; \ + (X)->tp = tp; \ + (X)->lasttp = lasttp; \ + (X)->tokval = tokval; \ + (X)->tokstr = tokstr; \ + (X)->noeval = noeval; \ + (X)->lval = curlval; \ + } while (0) + +#define RESTORETOK(X) \ + do { \ + curtok = (X)->curtok; \ + lasttok = (X)->lasttok; \ + tp = (X)->tp; \ + lasttp = (X)->lasttp; \ + tokval = (X)->tokval; \ + tokstr = (X)->tokstr; \ + noeval = (X)->noeval; \ + curlval = (X)->lval; \ + } while (0) + +/* Push and save away the contents of the globals describing the + current expression context. */ +static void +pushexp () +{ + EXPR_CONTEXT *context; + + if (expr_depth >= MAX_EXPR_RECURSION_LEVEL) + evalerror (_("expression recursion level exceeded")); + + if (expr_depth >= expr_stack_size) + { + expr_stack_size += EXPR_STACK_GROW_SIZE; + expr_stack = (EXPR_CONTEXT **)xrealloc (expr_stack, expr_stack_size * sizeof (EXPR_CONTEXT *)); + } + + context = (EXPR_CONTEXT *)xmalloc (sizeof (EXPR_CONTEXT)); + + context->expression = expression; + SAVETOK(context); + + expr_stack[expr_depth++] = context; +} + +/* Pop the the contents of the expression context stack into the + globals describing the current expression context. */ +static void +popexp () +{ + EXPR_CONTEXT *context; + + if (expr_depth == 0) + evalerror (_("recursion stack underflow")); + + context = expr_stack[--expr_depth]; + + expression = context->expression; + RESTORETOK (context); + + free (context); +} + +static void +expr_unwind () +{ + while (--expr_depth > 0) + { + if (expr_stack[expr_depth]->tokstr) + free (expr_stack[expr_depth]->tokstr); + + if (expr_stack[expr_depth]->expression) + free (expr_stack[expr_depth]->expression); + + free (expr_stack[expr_depth]); + } + free (expr_stack[expr_depth]); /* free the allocated EXPR_CONTEXT */ + + noeval = 0; /* XXX */ +} + +static void +expr_bind_variable (lhs, rhs) + char *lhs, *rhs; +{ + SHELL_VAR *v; + + v = bind_int_variable (lhs, rhs); + if (v && (readonly_p (v) || noassign_p (v))) + longjmp (evalbuf, 1); /* variable assignment error */ + stupidly_hack_special_variables (lhs); +} + +/* Rewrite tok, which is of the form vname[expression], to vname[ind], where + IND is the already-calculated value of expression. */ +static void +expr_bind_array_element (tok, ind, rhs) + char *tok; + arrayind_t ind; + char *rhs; +{ + char *lhs, *vname; + size_t llen; + char ibuf[INT_STRLEN_BOUND (arrayind_t) + 1], *istr; + + istr = fmtumax (ind, 10, ibuf, sizeof (ibuf), 0); + vname = array_variable_name (tok, (char **)NULL, (int *)NULL); + + llen = strlen (vname) + sizeof (ibuf) + 3; + lhs = xmalloc (llen); + + sprintf (lhs, "%s[%s]", vname, istr); /* XXX */ + + expr_bind_variable (lhs, rhs); +/*itrace("expr_bind_array_element: %s=%s", lhs, rhs);*/ + free (vname); + free (lhs); +} + +/* Evaluate EXPR, and return the arithmetic result. If VALIDP is + non-null, a zero is stored into the location to which it points + if the expression is invalid, non-zero otherwise. If a non-zero + value is returned in *VALIDP, the return value of evalexp() may + be used. + + The `while' loop after the longjmp is caught relies on the above + implementation of pushexp and popexp leaving in expr_stack[0] the + values that the variables had when the program started. That is, + the first things saved are the initial values of the variables that + were assigned at program startup or by the compiler. Therefore, it is + safe to let the loop terminate when expr_depth == 0, without freeing up + any of the expr_depth[0] stuff. */ +intmax_t +evalexp (expr, validp) + char *expr; + int *validp; +{ + intmax_t val; + int c; + procenv_t oevalbuf; + + val = 0; + noeval = 0; + + FASTCOPY (evalbuf, oevalbuf, sizeof (evalbuf)); + + c = setjmp (evalbuf); + + if (c) + { + FREE (tokstr); + FREE (expression); + tokstr = expression = (char *)NULL; + + expr_unwind (); + + if (validp) + *validp = 0; + return (0); + } + + val = subexpr (expr); + + if (validp) + *validp = 1; + + FASTCOPY (oevalbuf, evalbuf, sizeof (evalbuf)); + + return (val); +} + +static intmax_t +subexpr (expr) + char *expr; +{ + intmax_t val; + char *p; + + for (p = expr; p && *p && cr_whitespace (*p); p++) + ; + + if (p == NULL || *p == '\0') + return (0); + + pushexp (); + expression = savestring (expr); + tp = expression; + + curtok = lasttok = 0; + tokstr = (char *)NULL; + tokval = 0; + init_lvalue (&curlval); + lastlval = curlval; + + readtok (); + + val = EXP_HIGHEST (); + + if (curtok != 0) + evalerror (_("syntax error in expression")); + + FREE (tokstr); + FREE (expression); + + popexp (); + + return val; +} + +static intmax_t +expcomma () +{ + register intmax_t value; + + value = expassign (); + while (curtok == COMMA) + { + readtok (); + value = expassign (); + } + + return value; +} + +static intmax_t +expassign () +{ + register intmax_t value; + char *lhs, *rhs; + arrayind_t lind; + + value = expcond (); + if (curtok == EQ || curtok == OP_ASSIGN) + { + int special, op; + intmax_t lvalue; + + special = curtok == OP_ASSIGN; + + if (lasttok != STR) + evalerror (_("attempted assignment to non-variable")); + + if (special) + { + op = assigntok; /* a OP= b */ + lvalue = value; + } + + lhs = savestring (tokstr); + /* save ind in case rhs is string var and evaluation overwrites it */ + lind = curlval.ind; + readtok (); + value = expassign (); + + if (special) + { + if ((op == DIV || op == MOD) && value == 0) + { + if (noeval == 0) + evalerror (_("division by 0")); + else + value = 1; + } + + switch (op) + { + case MUL: + lvalue *= value; + break; + case DIV: + lvalue /= value; + break; + case MOD: + lvalue %= value; + break; + case PLUS: + lvalue += value; + break; + case MINUS: + lvalue -= value; + break; + case LSH: + lvalue <<= value; + break; + case RSH: + lvalue >>= value; + break; + case BAND: + lvalue &= value; + break; + case BOR: + lvalue |= value; + break; + case BXOR: + lvalue ^= value; + break; + default: + free (lhs); + evalerror (_("bug: bad expassign token")); + break; + } + value = lvalue; + } + + rhs = itos (value); + if (noeval == 0) + { + if (lind != -1) + expr_bind_array_element (lhs, lind, rhs); + else + expr_bind_variable (lhs, rhs); + } + free (rhs); + free (lhs); + FREE (tokstr); + tokstr = (char *)NULL; /* For freeing on errors. */ + } + return (value); +} + +/* Conditional expression (expr?expr:expr) */ +static intmax_t +expcond () +{ + intmax_t cval, val1, val2, rval; + int set_noeval; + EXPR_CONTEXT ec; + + set_noeval = 0; + rval = cval = explor (); + if (curtok == QUES) /* found conditional expr */ + { + readtok (); + if (curtok == 0 || curtok == COL) + evalerror (_("expression expected")); + if (cval == 0) + { + set_noeval = 1; + noeval++; + } + + val1 = EXP_HIGHEST (); + + if (set_noeval) + noeval--; + if (curtok != COL) + evalerror (_("`:' expected for conditional expression")); + readtok (); + if (curtok == 0) + evalerror (_("expression expected")); + set_noeval = 0; + if (cval) + { + set_noeval = 1; + noeval++; + } + + val2 = expcond (); + if (set_noeval) + noeval--; + rval = cval ? val1 : val2; + lasttok = COND; + } + return rval; +} + +/* Logical OR. */ +static intmax_t +explor () +{ + register intmax_t val1, val2; + int set_noeval; + + val1 = expland (); + + while (curtok == LOR) + { + set_noeval = 0; + if (val1 != 0) + { + noeval++; + set_noeval = 1; + } + readtok (); + val2 = expland (); + if (set_noeval) + noeval--; + val1 = val1 || val2; + lasttok = LOR; + } + + return (val1); +} + +/* Logical AND. */ +static intmax_t +expland () +{ + register intmax_t val1, val2; + int set_noeval; + + val1 = expbor (); + + while (curtok == LAND) + { + set_noeval = 0; + if (val1 == 0) + { + set_noeval = 1; + noeval++; + } + readtok (); + val2 = expbor (); + if (set_noeval) + noeval--; + val1 = val1 && val2; + lasttok = LAND; + } + + return (val1); +} + +/* Bitwise OR. */ +static intmax_t +expbor () +{ + register intmax_t val1, val2; + + val1 = expbxor (); + + while (curtok == BOR) + { + readtok (); + val2 = expbxor (); + val1 = val1 | val2; + } + + return (val1); +} + +/* Bitwise XOR. */ +static intmax_t +expbxor () +{ + register intmax_t val1, val2; + + val1 = expband (); + + while (curtok == BXOR) + { + readtok (); + val2 = expband (); + val1 = val1 ^ val2; + } + + return (val1); +} + +/* Bitwise AND. */ +static intmax_t +expband () +{ + register intmax_t val1, val2; + + val1 = exp5 (); + + while (curtok == BAND) + { + readtok (); + val2 = exp5 (); + val1 = val1 & val2; + } + + return (val1); +} + +static intmax_t +exp5 () +{ + register intmax_t val1, val2; + + val1 = exp4 (); + + while ((curtok == EQEQ) || (curtok == NEQ)) + { + int op = curtok; + + readtok (); + val2 = exp4 (); + if (op == EQEQ) + val1 = (val1 == val2); + else if (op == NEQ) + val1 = (val1 != val2); + } + return (val1); +} + +static intmax_t +exp4 () +{ + register intmax_t val1, val2; + + val1 = expshift (); + while ((curtok == LEQ) || + (curtok == GEQ) || + (curtok == LT) || + (curtok == GT)) + { + int op = curtok; + + readtok (); + val2 = expshift (); + + if (op == LEQ) + val1 = val1 <= val2; + else if (op == GEQ) + val1 = val1 >= val2; + else if (op == LT) + val1 = val1 < val2; + else /* (op == GT) */ + val1 = val1 > val2; + } + return (val1); +} + +/* Left and right shifts. */ +static intmax_t +expshift () +{ + register intmax_t val1, val2; + + val1 = exp3 (); + + while ((curtok == LSH) || (curtok == RSH)) + { + int op = curtok; + + readtok (); + val2 = exp3 (); + + if (op == LSH) + val1 = val1 << val2; + else + val1 = val1 >> val2; + } + + return (val1); +} + +static intmax_t +exp3 () +{ + register intmax_t val1, val2; + + val1 = exp2 (); + + while ((curtok == PLUS) || (curtok == MINUS)) + { + int op = curtok; + + readtok (); + val2 = exp2 (); + + if (op == PLUS) + val1 += val2; + else if (op == MINUS) + val1 -= val2; + } + return (val1); +} + +static intmax_t +exp2 () +{ + register intmax_t val1, val2; + + val1 = exppower (); + + while ((curtok == MUL) || + (curtok == DIV) || + (curtok == MOD)) + { + int op = curtok; + + readtok (); + + val2 = exppower (); + + if (((op == DIV) || (op == MOD)) && (val2 == 0)) + { + if (noeval == 0) + evalerror (_("division by 0")); + else + val2 = 1; + } + + if (op == MUL) + val1 *= val2; + else if (op == DIV) + val1 /= val2; + else if (op == MOD) + val1 %= val2; + } + return (val1); +} + +static intmax_t +exppower () +{ + register intmax_t val1, val2, c; + + val1 = exp1 (); + while (curtok == POWER) + { + readtok (); + val2 = exppower (); /* exponentiation is right-associative */ + if (val2 == 0) + return (1); + if (val2 < 0) + evalerror (_("exponent less than 0")); + for (c = 1; val2--; c *= val1) + ; + val1 = c; + } + return (val1); +} + +static intmax_t +exp1 () +{ + register intmax_t val; + + if (curtok == NOT) + { + readtok (); + val = !exp1 (); + } + else if (curtok == BNOT) + { + readtok (); + val = ~exp1 (); + } + else if (curtok == MINUS) + { + readtok (); + val = - exp1 (); + } + else if (curtok == PLUS) + { + readtok (); + val = exp1 (); + } + else + val = exp0 (); + + return (val); +} + +static intmax_t +exp0 () +{ + register intmax_t val = 0, v2; + char *vincdec; + int stok; + EXPR_CONTEXT ec; + + /* XXX - might need additional logic here to decide whether or not + pre-increment or pre-decrement is legal at this point. */ + if (curtok == PREINC || curtok == PREDEC) + { + stok = lasttok = curtok; + readtok (); + if (curtok != STR) + /* readtok() catches this */ + evalerror (_("identifier expected after pre-increment or pre-decrement")); + + v2 = tokval + ((stok == PREINC) ? 1 : -1); + vincdec = itos (v2); + if (noeval == 0) + { + if (curlval.ind != -1) + expr_bind_array_element (curlval.tokstr, curlval.ind, vincdec); + else + expr_bind_variable (tokstr, vincdec); + } + free (vincdec); + val = v2; + + curtok = NUM; /* make sure --x=7 is flagged as an error */ + readtok (); + } + else if (curtok == LPAR) + { + readtok (); + val = EXP_HIGHEST (); + + if (curtok != RPAR) /* ( */ + evalerror (_("missing `)'")); + + /* Skip over closing paren. */ + readtok (); + } + else if ((curtok == NUM) || (curtok == STR)) + { + val = tokval; + if (curtok == STR) + { + SAVETOK (&ec); + tokstr = (char *)NULL; /* keep it from being freed */ + noeval = 1; + readtok (); + stok = curtok; + + /* post-increment or post-decrement */ + if (stok == POSTINC || stok == POSTDEC) + { + /* restore certain portions of EC */ + tokstr = ec.tokstr; + noeval = ec.noeval; + curlval = ec.lval; + lasttok = STR; /* ec.curtok */ + + v2 = val + ((stok == POSTINC) ? 1 : -1); + vincdec = itos (v2); + if (noeval == 0) + { + if (curlval.ind != -1) + expr_bind_array_element (curlval.tokstr, curlval.ind, vincdec); + else + expr_bind_variable (tokstr, vincdec); + } + free (vincdec); + curtok = NUM; /* make sure x++=7 is flagged as an error */ + } + else + { + if (stok == STR) /* free new tokstr before old one is restored */ + FREE (tokstr); + RESTORETOK (&ec); + } + + } + + readtok (); + } + else + evalerror (_("syntax error: operand expected")); + + return (val); +} + +static void +init_lvalue (lv) + struct lvalue *lv; +{ + lv->tokstr = 0; + lv->tokvar = 0; + lv->tokval = lv->ind = -1; +} + +static struct lvalue * +alloc_lvalue () +{ + struct lvalue *lv; + + lv = xmalloc (sizeof (struct lvalue)); + init_lvalue (lv); + return (lv); +} + +static void +free_lvalue (lv) + struct lvalue *lv; +{ + free (lv); /* should be inlined */ +} + +static intmax_t +expr_streval (tok, e, lvalue) + char *tok; + int e; + struct lvalue *lvalue; +{ + SHELL_VAR *v; + char *value; + intmax_t tval; +#if defined (ARRAY_VARS) + arrayind_t ind; +#endif + + /* [[[[[ */ +#if defined (ARRAY_VARS) + v = (e == ']') ? array_variable_part (tok, (char **)0, (int *)0) : find_variable (tok); +#else + v = find_variable (tok); +#endif + + if ((v == 0 || invisible_p (v)) && unbound_vars_is_error) + { +#if defined (ARRAY_VARS) + value = (e == ']') ? array_variable_name (tok, (char **)0, (int *)0) : tok; +#else + value = tok; +#endif + + last_command_exit_value = EXECUTION_FAILURE; + err_unboundvar (value); + +#if defined (ARRAY_VARS) + if (e == ']') + FREE (value); /* array_variable_name returns new memory */ +#endif + + if (interactive_shell) + { + expr_unwind (); + top_level_cleanup (); + jump_to_top_level (DISCARD); + } + else + jump_to_top_level (FORCE_EOF); + } + + ind = -1; +#if defined (ARRAY_VARS) + /* Second argument of 0 to get_array_value means that we don't allow + references like array[@]. In this case, get_array_value is just + like get_variable_value in that it does not return newly-allocated + memory or quote the results. */ + value = (e == ']') ? get_array_value (tok, 0, (int *)NULL, &ind) : get_variable_value (v); +#else + value = get_variable_value (v); +#endif + + tval = (value && *value) ? subexpr (value) : 0; + + if (lvalue) + { + lvalue->tokstr = tok; /* XXX */ + lvalue->tokval = tval; + lvalue->tokvar = v; /* XXX */ + lvalue->ind = ind; + } + + return (tval); +} + +static int +_is_multiop (c) + int c; +{ + switch (c) + { + case EQEQ: + case NEQ: + case LEQ: + case GEQ: + case LAND: + case LOR: + case LSH: + case RSH: + case OP_ASSIGN: + case COND: + case POWER: + case PREINC: + case PREDEC: + case POSTINC: + case POSTDEC: + return 1; + default: + return 0; + } +} + +static int +_is_arithop (c) + int c; +{ + switch (c) + { + case EQ: + case GT: + case LT: + case PLUS: + case MINUS: + case MUL: + case DIV: + case MOD: + case NOT: + case LPAR: + case RPAR: + case BAND: + case BOR: + case BXOR: + case BNOT: + return 1; /* operator tokens */ + case QUES: + case COL: + case COMMA: + return 1; /* questionable */ + default: + return 0; /* anything else is invalid */ + } +} + +/* Lexical analyzer/token reader for the expression evaluator. Reads the + next token and puts its value into curtok, while advancing past it. + Updates value of tp. May also set tokval (for number) or tokstr (for + string). */ +static void +readtok () +{ + register char *cp, *xp; + register unsigned char c, c1; + register int e; + struct lvalue lval; + + /* Skip leading whitespace. */ + cp = tp; + c = e = 0; + while (cp && (c = *cp) && (cr_whitespace (c))) + cp++; + + if (c) + cp++; + + if (c == '\0') + { + lasttok = curtok; + curtok = 0; + tp = cp; + return; + } + lasttp = tp = cp - 1; + + if (legal_variable_starter (c)) + { + /* variable names not preceded with a dollar sign are shell variables. */ + char *savecp; + EXPR_CONTEXT ec; + int peektok; + + while (legal_variable_char (c)) + c = *cp++; + + c = *--cp; + +#if defined (ARRAY_VARS) + if (c == '[') + { + e = skipsubscript (cp, 0, 0); + if (cp[e] == ']') + { + cp += e + 1; + c = *cp; + e = ']'; + } + else + evalerror (bash_badsub_errmsg); + } +#endif /* ARRAY_VARS */ + + *cp = '\0'; + FREE (tokstr); + tokstr = savestring (tp); + *cp = c; + + /* XXX - make peektok part of saved token state? */ + SAVETOK (&ec); + tokstr = (char *)NULL; /* keep it from being freed */ + tp = savecp = cp; + noeval = 1; + curtok = STR; + readtok (); + peektok = curtok; + if (peektok == STR) /* free new tokstr before old one is restored */ + FREE (tokstr); + RESTORETOK (&ec); + cp = savecp; + + /* The tests for PREINC and PREDEC aren't strictly correct, but they + preserve old behavior if a construct like --x=9 is given. */ + if (lasttok == PREINC || lasttok == PREDEC || peektok != EQ) + { + lastlval = curlval; + tokval = expr_streval (tokstr, e, &curlval); + } + else + tokval = 0; + + lasttok = curtok; + curtok = STR; + } + else if (DIGIT(c)) + { + while (ISALNUM (c) || c == '#' || c == '@' || c == '_') + c = *cp++; + + c = *--cp; + *cp = '\0'; + + tokval = strlong (tp); + *cp = c; + lasttok = curtok; + curtok = NUM; + } + else + { + c1 = *cp++; + if ((c == EQ) && (c1 == EQ)) + c = EQEQ; + else if ((c == NOT) && (c1 == EQ)) + c = NEQ; + else if ((c == GT) && (c1 == EQ)) + c = GEQ; + else if ((c == LT) && (c1 == EQ)) + c = LEQ; + else if ((c == LT) && (c1 == LT)) + { + if (*cp == '=') /* a <<= b */ + { + assigntok = LSH; + c = OP_ASSIGN; + cp++; + } + else + c = LSH; + } + else if ((c == GT) && (c1 == GT)) + { + if (*cp == '=') + { + assigntok = RSH; /* a >>= b */ + c = OP_ASSIGN; + cp++; + } + else + c = RSH; + } + else if ((c == BAND) && (c1 == BAND)) + c = LAND; + else if ((c == BOR) && (c1 == BOR)) + c = LOR; + else if ((c == '*') && (c1 == '*')) + c = POWER; + else if ((c == '-' || c == '+') && c1 == c && curtok == STR) + c = (c == '-') ? POSTDEC : POSTINC; + else if ((c == '-' || c == '+') && c1 == c) + { + /* Quickly scan forward to see if this is followed by optional + whitespace and an identifier. */ + xp = cp; + while (xp && *xp && cr_whitespace (*xp)) + xp++; + if (legal_variable_starter ((unsigned char)*xp)) + c = (c == '-') ? PREDEC : PREINC; + else + cp--; /* not preinc or predec, so unget the character */ + } + else if (c1 == EQ && member (c, "*/%+-&^|")) + { + assigntok = c; /* a OP= b */ + c = OP_ASSIGN; + } + else if (_is_arithop (c) == 0) + { + cp--; + /* use curtok, since it hasn't been copied to lasttok yet */ + if (curtok == 0 || _is_arithop (curtok) || _is_multiop (curtok)) + evalerror (_("syntax error: operand expected")); + else + evalerror (_("syntax error: invalid arithmetic operator")); + } + else + cp--; /* `unget' the character */ + + /* Should check here to make sure that the current character is one + of the recognized operators and flag an error if not. Could create + a character map the first time through and check it on subsequent + calls. */ + lasttok = curtok; + curtok = c; + } + tp = cp; +} + +static void +evalerror (msg) + const char *msg; +{ + char *name, *t; + + name = this_command_name; + for (t = expression; whitespace (*t); t++) + ; + internal_error (_("%s%s%s: %s (error token is \"%s\")"), + name ? name : "", name ? ": " : "", t, + msg, (lasttp && *lasttp) ? lasttp : ""); + longjmp (evalbuf, 1); +} + +/* Convert a string to an intmax_t integer, with an arbitrary base. + 0nnn -> base 8 + 0[Xx]nn -> base 16 + Anything else: [base#]number (this is implemented to match ksh93) + + Base may be >=2 and <=64. If base is <= 36, the numbers are drawn + from [0-9][a-zA-Z], and lowercase and uppercase letters may be used + interchangably. If base is > 36 and <= 64, the numbers are drawn + from [0-9][a-z][A-Z]_@ (a = 10, z = 35, A = 36, Z = 61, @ = 62, _ = 63 -- + you get the picture). */ + +static intmax_t +strlong (num) + char *num; +{ + register char *s; + register unsigned char c; + int base, foundbase; + intmax_t val; + + s = num; + + base = 10; + foundbase = 0; + if (*s == '0') + { + s++; + + if (*s == '\0') + return 0; + + /* Base 16? */ + if (*s == 'x' || *s == 'X') + { + base = 16; + s++; + } + else + base = 8; + foundbase++; + } + + val = 0; + for (c = *s++; c; c = *s++) + { + if (c == '#') + { + if (foundbase) + evalerror (_("invalid number")); + + /* Illegal base specifications raise an evaluation error. */ + if (val < 2 || val > 64) + evalerror (_("invalid arithmetic base")); + + base = val; + val = 0; + foundbase++; + } + else if (ISALNUM(c) || (c == '_') || (c == '@')) + { + if (DIGIT(c)) + c = TODIGIT(c); + else if (c >= 'a' && c <= 'z') + c -= 'a' - 10; + else if (c >= 'A' && c <= 'Z') + c -= 'A' - ((base <= 36) ? 10 : 36); + else if (c == '@') + c = 62; + else if (c == '_') + c = 63; + + if (c >= base) + evalerror (_("value too great for base")); + + val = (val * base) + c; + } + else + break; + } + + return (val); +} + +#if defined (EXPR_TEST) +void * +xmalloc (n) + int n; +{ + return (malloc (n)); +} + +void * +xrealloc (s, n) + char *s; + int n; +{ + return (realloc (s, n)); +} + +SHELL_VAR *find_variable () { return 0;} +SHELL_VAR *bind_variable () { return 0; } + +char *get_string_value () { return 0; } + +procenv_t top_level; + +main (argc, argv) + int argc; + char **argv; +{ + register int i; + intmax_t v; + int expok; + + if (setjmp (top_level)) + exit (0); + + for (i = 1; i < argc; i++) + { + v = evalexp (argv[i], &expok); + if (expok == 0) + fprintf (stderr, _("%s: expression error\n"), argv[i]); + else + printf ("'%s' -> %ld\n", argv[i], v); + } + exit (0); +} + +int +builtin_error (format, arg1, arg2, arg3, arg4, arg5) + char *format; +{ + fprintf (stderr, "expr: "); + fprintf (stderr, format, arg1, arg2, arg3, arg4, arg5); + fprintf (stderr, "\n"); + return 0; +} + +char * +itos (n) + intmax_t n; +{ + return ("42"); +} + +#endif /* EXPR_TEST */ diff --git a/lib/readline/callback.c b/lib/readline/callback.c index 7682cd07b..8465de0db 100644 --- a/lib/readline/callback.c +++ b/lib/readline/callback.c @@ -62,8 +62,10 @@ _rl_callback_generic_arg *_rl_callback_data = 0; whenever a complete line of input is ready. The user must then call rl_callback_read_char() every time some input is available, and rl_callback_read_char() will call the user's function with the complete - text read in at each end of line. The terminal is kept prepped and - signals handled all the time, except during calls to the user's function. */ + text read in at each end of line. The terminal is kept prepped + all the time, except during calls to the user's function. Signal + handlers are only installed when the application calls back into + readline, so readline doesn't `steal' signals from the application. */ rl_vcpfunc_t *rl_linefunc; /* user callback function */ static int in_handler; /* terminal_prepped and signals set? */ @@ -80,10 +82,6 @@ _rl_callback_newline () if (rl_prep_term_function) (*rl_prep_term_function) (_rl_meta_flag); - -#if defined (HANDLE_SIGNALS) - rl_set_signals (); -#endif } readline_internal_setup (); @@ -126,6 +124,11 @@ rl_callback_read_char () return; } +#if defined (HANDLE_SIGNALS) + /* Install signal handlers only when readline has control. */ + rl_set_signals (); +#endif + do { RL_CHECK_SIGNALS (); diff --git a/lib/readline/callback.c~ b/lib/readline/callback.c~ new file mode 100644 index 000000000..75322731e --- /dev/null +++ b/lib/readline/callback.c~ @@ -0,0 +1,274 @@ +/* callback.c -- functions to use readline as an X `callback' mechanism. */ + +/* Copyright (C) 1987-2009 Free Software Foundation, Inc. + + This file is part of the GNU Readline Library (Readline), a library + for reading lines of text with interactive input and history editing. + + Readline 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 3 of the License, or + (at your option) any later version. + + Readline 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 Readline. If not, see . +*/ + +#define READLINE_LIBRARY + +#if defined (HAVE_CONFIG_H) +# include +#endif + +#include "rlconf.h" + +#if defined (READLINE_CALLBACKS) + +#include + +#ifdef HAVE_STDLIB_H +# include +#else +# include "ansi_stdlib.h" +#endif + +#include + +/* System-specific feature definitions and include files. */ +#include "rldefs.h" +#include "readline.h" +#include "rlprivate.h" +#include "xmalloc.h" + +/* Private data for callback registration functions. See comments in + rl_callback_read_char for more details. */ +_rl_callback_func_t *_rl_callback_func = 0; +_rl_callback_generic_arg *_rl_callback_data = 0; + +/* **************************************************************** */ +/* */ +/* Callback Readline Functions */ +/* */ +/* **************************************************************** */ + +/* Allow using readline in situations where a program may have multiple + things to handle at once, and dispatches them via select(). Call + rl_callback_handler_install() with the prompt and a function to call + whenever a complete line of input is ready. The user must then + call rl_callback_read_char() every time some input is available, and + rl_callback_read_char() will call the user's function with the complete + text read in at each end of line. The terminal is kept prepped and + signals handled all the time, except during calls to the user's function. */ + +rl_vcpfunc_t *rl_linefunc; /* user callback function */ +static int in_handler; /* terminal_prepped and signals set? */ + +/* Make sure the terminal is set up, initialize readline, and prompt. */ +static void +_rl_callback_newline () +{ + rl_initialize (); + + if (in_handler == 0) + { + in_handler = 1; + + if (rl_prep_term_function) + (*rl_prep_term_function) (_rl_meta_flag); + } + + readline_internal_setup (); + RL_CHECK_SIGNALS (); +} + +/* Install a readline handler, set up the terminal, and issue the prompt. */ +void +rl_callback_handler_install (prompt, linefunc) + const char *prompt; + rl_vcpfunc_t *linefunc; +{ + rl_set_prompt (prompt); + RL_SETSTATE (RL_STATE_CALLBACK); + rl_linefunc = linefunc; + _rl_callback_newline (); +} + +/* Read one character, and dispatch to the handler if it ends the line. */ +void +rl_callback_read_char () +{ + char *line; + int eof, jcode; + static procenv_t olevel; + + if (rl_linefunc == NULL) + { + _rl_errmsg ("readline_callback_read_char() called with no handler!"); + abort (); + } + + memcpy ((void *)olevel, (void *)_rl_top_level, sizeof (procenv_t)); + jcode = setjmp (_rl_top_level); + if (jcode) + { + (*rl_redisplay_function) (); + _rl_want_redisplay = 0; + memcpy ((void *)_rl_top_level, (void *)olevel, sizeof (procenv_t)); + return; + } + +#if defined (HANDLE_SIGNALS) + /* Install signal handlers only when readline has control. */ + rl_set_signals (); +#endif + + do + { + RL_CHECK_SIGNALS (); + if (RL_ISSTATE (RL_STATE_ISEARCH)) + { + eof = _rl_isearch_callback (_rl_iscxt); + if (eof == 0 && (RL_ISSTATE (RL_STATE_ISEARCH) == 0) && RL_ISSTATE (RL_STATE_INPUTPENDING)) + rl_callback_read_char (); + + return; + } + else if (RL_ISSTATE (RL_STATE_NSEARCH)) + { + eof = _rl_nsearch_callback (_rl_nscxt); + return; + } +#if defined (VI_MODE) + else if (RL_ISSTATE (RL_STATE_VIMOTION)) + { + eof = _rl_vi_domove_callback (_rl_vimvcxt); + /* Should handle everything, including cleanup, numeric arguments, + and turning off RL_STATE_VIMOTION */ + if (RL_ISSTATE (RL_STATE_NUMERICARG) == 0) + _rl_internal_char_cleanup (); + + return; + } +#endif + else if (RL_ISSTATE (RL_STATE_NUMERICARG)) + { + eof = _rl_arg_callback (_rl_argcxt); + if (eof == 0 && (RL_ISSTATE (RL_STATE_NUMERICARG) == 0) && RL_ISSTATE (RL_STATE_INPUTPENDING)) + rl_callback_read_char (); + /* XXX - this should handle _rl_last_command_was_kill better */ + else if (RL_ISSTATE (RL_STATE_NUMERICARG) == 0) + _rl_internal_char_cleanup (); + + return; + } + else if (RL_ISSTATE (RL_STATE_MULTIKEY)) + { + eof = _rl_dispatch_callback (_rl_kscxt); /* For now */ + while ((eof == -1 || eof == -2) && RL_ISSTATE (RL_STATE_MULTIKEY) && _rl_kscxt && (_rl_kscxt->flags & KSEQ_DISPATCHED)) + eof = _rl_dispatch_callback (_rl_kscxt); + if (RL_ISSTATE (RL_STATE_MULTIKEY) == 0) + { + _rl_internal_char_cleanup (); + _rl_want_redisplay = 1; + } + } + else if (_rl_callback_func) + { + /* This allows functions that simply need to read an additional + character (like quoted-insert) to register a function to be + called when input is available. _rl_callback_data is simply a + pointer to a struct that has the argument count originally + passed to the registering function and space for any additional + parameters. */ + eof = (*_rl_callback_func) (_rl_callback_data); + /* If the function `deregisters' itself, make sure the data is + cleaned up. */ + if (_rl_callback_func == 0) + { + if (_rl_callback_data) + { + _rl_callback_data_dispose (_rl_callback_data); + _rl_callback_data = 0; + } + _rl_internal_char_cleanup (); + } + } + else + eof = readline_internal_char (); + + RL_CHECK_SIGNALS (); + if (rl_done == 0 && _rl_want_redisplay) + { + (*rl_redisplay_function) (); + _rl_want_redisplay = 0; + } + + if (rl_done) + { + line = readline_internal_teardown (eof); + + if (rl_deprep_term_function) + (*rl_deprep_term_function) (); +#if defined (HANDLE_SIGNALS) + rl_clear_signals (); +#endif + in_handler = 0; + (*rl_linefunc) (line); + + /* If the user did not clear out the line, do it for him. */ + if (rl_line_buffer[0]) + _rl_init_line_state (); + + /* Redisplay the prompt if readline_handler_{install,remove} + not called. */ + if (in_handler == 0 && rl_linefunc) + _rl_callback_newline (); + } + } + while (rl_pending_input || _rl_pushed_input_available () || RL_ISSTATE (RL_STATE_MACROINPUT)); +} + +/* Remove the handler, and make sure the terminal is in its normal state. */ +void +rl_callback_handler_remove () +{ + rl_linefunc = NULL; + RL_UNSETSTATE (RL_STATE_CALLBACK); + RL_CHECK_SIGNALS (); + if (in_handler) + { + in_handler = 0; + if (rl_deprep_term_function) + (*rl_deprep_term_function) (); +#if defined (HANDLE_SIGNALS) + rl_clear_signals (); +#endif + } +} + +_rl_callback_generic_arg * +_rl_callback_data_alloc (count) + int count; +{ + _rl_callback_generic_arg *arg; + + arg = (_rl_callback_generic_arg *)xmalloc (sizeof (_rl_callback_generic_arg)); + arg->count = count; + + arg->i1 = arg->i2 = 0; + + return arg; +} + +void _rl_callback_data_dispose (arg) + _rl_callback_generic_arg *arg; +{ + xfree (arg); +} + +#endif diff --git a/lib/readline/chardefs.h b/lib/readline/chardefs.h index e76c34b0c..1fa1b089d 100644 --- a/lib/readline/chardefs.h +++ b/lib/readline/chardefs.h @@ -72,7 +72,7 @@ # define IN_CTYPE_DOMAIN(c) isascii(c) #endif -#if !defined (isxdigit) && !defined (HAVE_ISXDIGIT) +#if !defined (isxdigit) && !defined (HAVE_ISXDIGIT) && !defined (__cplusplus) # define isxdigit(c) (isdigit((c)) || ((c) >= 'a' && (c) <= 'f') || ((c) >= 'A' && (c) <= 'F')) #endif diff --git a/lib/readline/chardefs.h~ b/lib/readline/chardefs.h~ new file mode 100644 index 000000000..e76c34b0c --- /dev/null +++ b/lib/readline/chardefs.h~ @@ -0,0 +1,164 @@ +/* chardefs.h -- Character definitions for readline. */ + +/* Copyright (C) 1994-2009 Free Software Foundation, Inc. + + This file is part of the GNU Readline Library (Readline), a library + for reading lines of text with interactive input and history editing. + + Readline 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 3 of the License, or + (at your option) any later version. + + Readline 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 Readline. If not, see . +*/ + +#ifndef _CHARDEFS_H_ +#define _CHARDEFS_H_ + +#include + +#if defined (HAVE_CONFIG_H) +# if defined (HAVE_STRING_H) +# if ! defined (STDC_HEADERS) && defined (HAVE_MEMORY_H) +# include +# endif +# include +# endif /* HAVE_STRING_H */ +# if defined (HAVE_STRINGS_H) +# include +# endif /* HAVE_STRINGS_H */ +#else +# include +#endif /* !HAVE_CONFIG_H */ + +#ifndef whitespace +#define whitespace(c) (((c) == ' ') || ((c) == '\t')) +#endif + +#ifdef CTRL +# undef CTRL +#endif +#ifdef UNCTRL +# undef UNCTRL +#endif + +/* Some character stuff. */ +#define control_character_threshold 0x020 /* Smaller than this is control. */ +#define control_character_mask 0x1f /* 0x20 - 1 */ +#define meta_character_threshold 0x07f /* Larger than this is Meta. */ +#define control_character_bit 0x40 /* 0x000000, must be off. */ +#define meta_character_bit 0x080 /* x0000000, must be on. */ +#define largest_char 255 /* Largest character value. */ + +#define CTRL_CHAR(c) ((c) < control_character_threshold && (((c) & 0x80) == 0)) +#define META_CHAR(c) ((c) > meta_character_threshold && (c) <= largest_char) + +#define CTRL(c) ((c) & control_character_mask) +#define META(c) ((c) | meta_character_bit) + +#define UNMETA(c) ((c) & (~meta_character_bit)) +#define UNCTRL(c) _rl_to_upper(((c)|control_character_bit)) + +#if defined STDC_HEADERS || (!defined (isascii) && !defined (HAVE_ISASCII)) +# define IN_CTYPE_DOMAIN(c) 1 +#else +# define IN_CTYPE_DOMAIN(c) isascii(c) +#endif + +#if !defined (isxdigit) && !defined (HAVE_ISXDIGIT) +# define isxdigit(c) (isdigit((c)) || ((c) >= 'a' && (c) <= 'f') || ((c) >= 'A' && (c) <= 'F')) +#endif + +#if defined (CTYPE_NON_ASCII) +# define NON_NEGATIVE(c) 1 +#else +# define NON_NEGATIVE(c) ((unsigned char)(c) == (c)) +#endif + +/* Some systems define these; we want our definitions. */ +#undef ISPRINT + +/* Beware: these only work with single-byte ASCII characters. */ + +#define ISALNUM(c) (IN_CTYPE_DOMAIN (c) && isalnum (c)) +#define ISALPHA(c) (IN_CTYPE_DOMAIN (c) && isalpha (c)) +#define ISDIGIT(c) (IN_CTYPE_DOMAIN (c) && isdigit (c)) +#define ISLOWER(c) (IN_CTYPE_DOMAIN (c) && islower (c)) +#define ISPRINT(c) (IN_CTYPE_DOMAIN (c) && isprint (c)) +#define ISUPPER(c) (IN_CTYPE_DOMAIN (c) && isupper (c)) +#define ISXDIGIT(c) (IN_CTYPE_DOMAIN (c) && isxdigit (c)) + +#define _rl_lowercase_p(c) (NON_NEGATIVE(c) && ISLOWER(c)) +#define _rl_uppercase_p(c) (NON_NEGATIVE(c) && ISUPPER(c)) +#define _rl_digit_p(c) ((c) >= '0' && (c) <= '9') + +#define _rl_pure_alphabetic(c) (NON_NEGATIVE(c) && ISALPHA(c)) +#define ALPHABETIC(c) (NON_NEGATIVE(c) && ISALNUM(c)) + +#ifndef _rl_to_upper +# define _rl_to_upper(c) (_rl_lowercase_p(c) ? toupper((unsigned char)c) : (c)) +# define _rl_to_lower(c) (_rl_uppercase_p(c) ? tolower((unsigned char)c) : (c)) +#endif + +#ifndef _rl_digit_value +# define _rl_digit_value(x) ((x) - '0') +#endif + +#ifndef _rl_isident +# define _rl_isident(c) (ISALNUM(c) || (c) == '_') +#endif + +#ifndef ISOCTAL +# define ISOCTAL(c) ((c) >= '0' && (c) <= '7') +#endif +#define OCTVALUE(c) ((c) - '0') + +#define HEXVALUE(c) \ + (((c) >= 'a' && (c) <= 'f') \ + ? (c)-'a'+10 \ + : (c) >= 'A' && (c) <= 'F' ? (c)-'A'+10 : (c)-'0') + +#ifndef NEWLINE +#define NEWLINE '\n' +#endif + +#ifndef RETURN +#define RETURN CTRL('M') +#endif + +#ifndef RUBOUT +#define RUBOUT 0x7f +#endif + +#ifndef TAB +#define TAB '\t' +#endif + +#ifdef ABORT_CHAR +#undef ABORT_CHAR +#endif +#define ABORT_CHAR CTRL('G') + +#ifdef PAGE +#undef PAGE +#endif +#define PAGE CTRL('L') + +#ifdef SPACE +#undef SPACE +#endif +#define SPACE ' ' /* XXX - was 0x20 */ + +#ifdef ESC +#undef ESC +#endif +#define ESC CTRL('[') + +#endif /* _CHARDEFS_H_ */ diff --git a/lib/readline/isearch.c b/lib/readline/isearch.c index a7b2be41f..9aba9d969 100644 --- a/lib/readline/isearch.c +++ b/lib/readline/isearch.c @@ -312,6 +312,8 @@ _rl_search_getchar (cxt) RL_UNSETSTATE(RL_STATE_MOREINPUT); #if defined (HANDLE_MULTIBYTE) + /* This ends up with C (and LASTC) being set to the last byte of the + multibyte character. In most cases c == lastc == mb[0] */ if (MB_CUR_MAX > 1 && rl_byte_oriented == 0) c = cxt->lastc = _rl_read_mbstring (cxt->lastc, cxt->mb, MB_LEN_MAX); #endif @@ -354,6 +356,18 @@ _rl_isearch_dispatch (cxt, c) interpret here. Right now we just save the most recent character that caused the index into a new keymap. */ cxt->prevc = c; +#if defined (HANDLE_MULTIBYTE) + if (MB_CUR_MAX > 1 && rl_byte_oriented == 0) + { + if (cxt->mb[1] == 0) + { + cxt->pmb[0] = c; /* XXX should be == cxt->mb[0] */ + cxt->pmb[1] = '\0'; + } + else + memcpy (cxt->pmb, cxt->mb, sizeof (cxt->pmb)); + } +#endif return 1; } @@ -392,24 +406,36 @@ _rl_isearch_dispatch (cxt, c) { rl_stuff_char (cxt->lastc); rl_execute_next (cxt->prevc); + /* XXX - do we insert everything in cxt->pmb? */ return (0); } - /* Otherwise, if the current character is mapped to self-insert (i.e., - not an editing command), and the previous character was a keymap - index, then we need to insert both the previous character and the - current character into the search string. */ + /* Otherwise, if the current character is mapped to self-insert or + nothing (i.e., not an editing command), and the previous character + was a keymap index, then we need to insert both the previous + character and the current character into the search string. */ else if (cxt->lastc > 0 && cxt->prevc > 0 && cxt->keymap[cxt->prevc].type == ISKMAP && - cxt->okeymap[cxt->lastc].type == ISFUNC && cxt->okeymap[cxt->lastc].function == rl_insert) + cxt->okeymap[cxt->lastc].type == ISFUNC && + (cxt->okeymap[cxt->lastc].function == rl_insert || cxt->okeymap[cxt->lastc].function == 0)) { /* Make lastc be the next character read */ + /* XXX - do we insert everything in cxt->mb? */ rl_execute_next (cxt->lastc); /* Dispatch on the previous character (insert into search string) */ cxt->lastc = cxt->prevc; +#if defined (HANDLE_MULTIBYTE) /* Have to overwrite cxt->mb here because dispatch uses it below */ - cxt->mb[0] = cxt->lastc; - cxt->mb[1] = '\0'; - + if (MB_CUR_MAX > 1 && rl_byte_oriented == 0) + { + if (cxt->pmb[1] == 0) + { + cxt->mb[0] = cxt->lastc; /* == cxt->prevc */ + cxt->mb[1] = '\0'; + } + else + memcpy (cxt->mb, cxt->pmb, sizeof (cxt->mb)); + } +#endif cxt->prevc = 0; } } @@ -577,8 +603,12 @@ _rl_isearch_dispatch (cxt, c) if (MB_CUR_MAX > 1 && rl_byte_oriented == 0) { int j, l; - for (j = 0, l = strlen (cxt->mb); j < l; ) - cxt->search_string[cxt->search_string_index++] = cxt->mb[j++]; + + if (cxt->mb[0] == 0 || cxt->mb[1] == 0) + cxt->search_string[cxt->search_string_index++] = cxt->mb[0]; + else + for (j = 0, l = RL_STRLEN (cxt->mb); j < l; ) + cxt->search_string[cxt->search_string_index++] = cxt->mb[j++]; } else #endif diff --git a/lib/readline/isearch.c~ b/lib/readline/isearch.c~ new file mode 100644 index 000000000..0f8f5e64c --- /dev/null +++ b/lib/readline/isearch.c~ @@ -0,0 +1,758 @@ +/* isearch.c - incremental searching */ + +/* **************************************************************** */ +/* */ +/* I-Search and Searching */ +/* */ +/* **************************************************************** */ + +/* Copyright (C) 1987-2011 Free Software Foundation, Inc. + + This file is part of the GNU Readline Library (Readline), a library + for reading lines of text with interactive input and history editing. + + Readline 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 3 of the License, or + (at your option) any later version. + + Readline 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 Readline. If not, see . +*/ + +#define READLINE_LIBRARY + +#if defined (HAVE_CONFIG_H) +# include +#endif + +#include + +#include + +#if defined (HAVE_UNISTD_H) +# include +#endif + +#if defined (HAVE_STDLIB_H) +# include +#else +# include "ansi_stdlib.h" +#endif + +#include "rldefs.h" +#include "rlmbutil.h" + +#include "readline.h" +#include "history.h" + +#include "rlprivate.h" +#include "xmalloc.h" + +/* Variables exported to other files in the readline library. */ +char *_rl_isearch_terminators = (char *)NULL; + +_rl_search_cxt *_rl_iscxt = 0; + +/* Variables imported from other files in the readline library. */ +extern HIST_ENTRY *_rl_saved_line_for_history; + +static int rl_search_history PARAMS((int, int)); + +static _rl_search_cxt *_rl_isearch_init PARAMS((int)); +static void _rl_isearch_fini PARAMS((_rl_search_cxt *)); +static int _rl_isearch_cleanup PARAMS((_rl_search_cxt *, int)); + +/* Last line found by the current incremental search, so we don't `find' + identical lines many times in a row. Now part of isearch context. */ +/* static char *prev_line_found; */ + +/* Last search string and its length. */ +static char *last_isearch_string; +static int last_isearch_string_len; + +static char * const default_isearch_terminators = "\033\012"; + +_rl_search_cxt * +_rl_scxt_alloc (type, flags) + int type, flags; +{ + _rl_search_cxt *cxt; + + cxt = (_rl_search_cxt *)xmalloc (sizeof (_rl_search_cxt)); + + cxt->type = type; + cxt->sflags = flags; + + cxt->search_string = 0; + cxt->search_string_size = cxt->search_string_index = 0; + + cxt->lines = 0; + cxt->allocated_line = 0; + cxt->hlen = cxt->hindex = 0; + + cxt->save_point = rl_point; + cxt->save_mark = rl_mark; + cxt->save_line = where_history (); + cxt->last_found_line = cxt->save_line; + cxt->prev_line_found = 0; + + cxt->save_undo_list = 0; + + cxt->keymap = _rl_keymap; + cxt->okeymap = _rl_keymap; + + cxt->history_pos = 0; + cxt->direction = 0; + + cxt->prevc = cxt->lastc = 0; + + cxt->sline = 0; + cxt->sline_len = cxt->sline_index = 0; + + cxt->search_terminators = 0; + + return cxt; +} + +void +_rl_scxt_dispose (cxt, flags) + _rl_search_cxt *cxt; + int flags; +{ + FREE (cxt->search_string); + FREE (cxt->allocated_line); + FREE (cxt->lines); + + xfree (cxt); +} + +/* Search backwards through the history looking for a string which is typed + interactively. Start with the current line. */ +int +rl_reverse_search_history (sign, key) + int sign, key; +{ + return (rl_search_history (-sign, key)); +} + +/* Search forwards through the history looking for a string which is typed + interactively. Start with the current line. */ +int +rl_forward_search_history (sign, key) + int sign, key; +{ + return (rl_search_history (sign, key)); +} + +/* Display the current state of the search in the echo-area. + SEARCH_STRING contains the string that is being searched for, + DIRECTION is zero for forward, or non-zero for reverse, + WHERE is the history list number of the current line. If it is + -1, then this line is the starting one. */ +static void +rl_display_search (search_string, reverse_p, where) + char *search_string; + int reverse_p, where; +{ + char *message; + int msglen, searchlen; + + searchlen = (search_string && *search_string) ? strlen (search_string) : 0; + + message = (char *)xmalloc (searchlen + 33); + msglen = 0; + +#if defined (NOTDEF) + if (where != -1) + { + sprintf (message, "[%d]", where + history_base); + msglen = strlen (message); + } +#endif /* NOTDEF */ + + message[msglen++] = '('; + + if (reverse_p) + { + strcpy (message + msglen, "reverse-"); + msglen += 8; + } + + strcpy (message + msglen, "i-search)`"); + msglen += 10; + + if (search_string) + { + strcpy (message + msglen, search_string); + msglen += searchlen; + } + + strcpy (message + msglen, "': "); + + rl_message ("%s", message); + xfree (message); + (*rl_redisplay_function) (); +} + +static _rl_search_cxt * +_rl_isearch_init (direction) + int direction; +{ + _rl_search_cxt *cxt; + register int i; + HIST_ENTRY **hlist; + + cxt = _rl_scxt_alloc (RL_SEARCH_ISEARCH, 0); + if (direction < 0) + cxt->sflags |= SF_REVERSE; + + cxt->search_terminators = _rl_isearch_terminators ? _rl_isearch_terminators + : default_isearch_terminators; + + /* Create an arrary of pointers to the lines that we want to search. */ + hlist = history_list (); + rl_maybe_replace_line (); + i = 0; + if (hlist) + for (i = 0; hlist[i]; i++); + + /* Allocate space for this many lines, +1 for the current input line, + and remember those lines. */ + cxt->lines = (char **)xmalloc ((1 + (cxt->hlen = i)) * sizeof (char *)); + for (i = 0; i < cxt->hlen; i++) + cxt->lines[i] = hlist[i]->line; + + if (_rl_saved_line_for_history) + cxt->lines[i] = _rl_saved_line_for_history->line; + else + { + /* Keep track of this so we can free it. */ + cxt->allocated_line = (char *)xmalloc (1 + strlen (rl_line_buffer)); + strcpy (cxt->allocated_line, &rl_line_buffer[0]); + cxt->lines[i] = cxt->allocated_line; + } + + cxt->hlen++; + + /* The line where we start the search. */ + cxt->history_pos = cxt->save_line; + + rl_save_prompt (); + + /* Initialize search parameters. */ + cxt->search_string = (char *)xmalloc (cxt->search_string_size = 128); + cxt->search_string[cxt->search_string_index = 0] = '\0'; + + /* Normalize DIRECTION into 1 or -1. */ + cxt->direction = (direction >= 0) ? 1 : -1; + + cxt->sline = rl_line_buffer; + cxt->sline_len = strlen (cxt->sline); + cxt->sline_index = rl_point; + + _rl_iscxt = cxt; /* save globally */ + + return cxt; +} + +static void +_rl_isearch_fini (cxt) + _rl_search_cxt *cxt; +{ + /* First put back the original state. */ + strcpy (rl_line_buffer, cxt->lines[cxt->save_line]); + + rl_restore_prompt (); + + /* Save the search string for possible later use. */ + FREE (last_isearch_string); + last_isearch_string = cxt->search_string; + last_isearch_string_len = cxt->search_string_index; + cxt->search_string = 0; + + if (cxt->last_found_line < cxt->save_line) + rl_get_previous_history (cxt->save_line - cxt->last_found_line, 0); + else + rl_get_next_history (cxt->last_found_line - cxt->save_line, 0); + + /* If the string was not found, put point at the end of the last matching + line. If last_found_line == orig_line, we didn't find any matching + history lines at all, so put point back in its original position. */ + if (cxt->sline_index < 0) + { + if (cxt->last_found_line == cxt->save_line) + cxt->sline_index = cxt->save_point; + else + cxt->sline_index = strlen (rl_line_buffer); + rl_mark = cxt->save_mark; + } + + rl_point = cxt->sline_index; + /* Don't worry about where to put the mark here; rl_get_previous_history + and rl_get_next_history take care of it. */ + + rl_clear_message (); +} + +int +_rl_search_getchar (cxt) + _rl_search_cxt *cxt; +{ + int c; + + /* Read a key and decide how to proceed. */ + RL_SETSTATE(RL_STATE_MOREINPUT); + c = cxt->lastc = rl_read_key (); + RL_UNSETSTATE(RL_STATE_MOREINPUT); + +#if defined (HANDLE_MULTIBYTE) + /* This ends up with C (and LASTC) being set to the last byte of the + multibyte character. In most cases c == lastc == mb[0] */ + if (MB_CUR_MAX > 1 && rl_byte_oriented == 0) + c = cxt->lastc = _rl_read_mbstring (cxt->lastc, cxt->mb, MB_LEN_MAX); +#endif + + return c; +} + +#define ENDSRCH_CHAR(c) \ + ((CTRL_CHAR (c) || META_CHAR (c) || (c) == RUBOUT) && ((c) != CTRL ('G'))) + +/* Process just-read character C according to isearch context CXT. Return + -1 if the caller should just free the context and return, 0 if we should + break out of the loop, and 1 if we should continue to read characters. */ +int +_rl_isearch_dispatch (cxt, c) + _rl_search_cxt *cxt; + int c; +{ + int n, wstart, wlen, limit, cval; + rl_command_func_t *f; + + f = (rl_command_func_t *)NULL; + + if (c < 0) + { + cxt->sflags |= SF_FAILED; + cxt->history_pos = cxt->last_found_line; + return -1; + } + + /* If we are moving into a new keymap, modify cxt->keymap and go on. + This can be a problem if c == ESC and we want to terminate the + incremental search, so we check */ + if (c >= 0 && cxt->keymap[c].type == ISKMAP && strchr (cxt->search_terminators, cxt->lastc) == 0) + { + cxt->keymap = FUNCTION_TO_KEYMAP (cxt->keymap, c); + cxt->sflags |= SF_CHGKMAP; + /* XXX - we should probably save this sequence, so we can do + something useful if this doesn't end up mapping to a command we + interpret here. Right now we just save the most recent character + that caused the index into a new keymap. */ + cxt->prevc = c; +#if defined (HANDLE_MULTIBYTE) + if (MB_CUR_MAX > 1 && rl_byte_oriented == 0) + { + if (cxt->mb[1] == 0) + { + cxt->pmb[0] = c; /* XXX should be == cxt->mb[0] */ + cxt->pmb[1] = '\0'; + } + else + memcpy (cxt->pmb, cxt->mb, sizeof (cxt->pmb)); + } +#endif + return 1; + } + + /* Translate the keys we do something with to opcodes. */ + if (c >= 0 && cxt->keymap[c].type == ISFUNC) + { + f = cxt->keymap[c].function; + + if (f == rl_reverse_search_history) + cxt->lastc = (cxt->sflags & SF_REVERSE) ? -1 : -2; + else if (f == rl_forward_search_history) + cxt->lastc = (cxt->sflags & SF_REVERSE) ? -2 : -1; + else if (f == rl_rubout) + cxt->lastc = -3; + else if (c == CTRL ('G') || f == rl_abort) + cxt->lastc = -4; + else if (c == CTRL ('W') || f == rl_unix_word_rubout) /* XXX */ + cxt->lastc = -5; + else if (c == CTRL ('Y') || f == rl_yank) /* XXX */ + cxt->lastc = -6; + } + + /* If we changed the keymap earlier while translating a key sequence into + a command, restore it now that we've succeeded. */ + if (cxt->sflags & SF_CHGKMAP) + { + cxt->keymap = cxt->okeymap; + cxt->sflags &= ~SF_CHGKMAP; + /* If we indexed into a new keymap, but didn't map to a command that + affects the search (lastc > 0), and the character that mapped to a + new keymap would have ended the search (ENDSRCH_CHAR(cxt->prevc)), + handle that now as if the previous char would have ended the search + and we would have read the current character. */ + /* XXX - should we check cxt->mb? */ + if (cxt->lastc > 0 && ENDSRCH_CHAR (cxt->prevc)) + { + rl_stuff_char (cxt->lastc); + rl_execute_next (cxt->prevc); + return (0); + } + /* Otherwise, if the current character is mapped to self-insert or + nothing (i.e., not an editing command), and the previous character + was a keymap index, then we need to insert both the previous + character and the current character into the search string. */ + else if (cxt->lastc > 0 && cxt->prevc > 0 && + cxt->keymap[cxt->prevc].type == ISKMAP && + cxt->okeymap[cxt->lastc].type == ISFUNC && + (cxt->okeymap[cxt->lastc].function == rl_insert || cxt->okeymap[cxt->lastc].function == 0)) + { + /* Make lastc be the next character read */ + rl_execute_next (cxt->lastc); + /* Dispatch on the previous character (insert into search string) */ + cxt->lastc = cxt->prevc; +#if defined (HANDLE_MULTIBYTE) + /* Have to overwrite cxt->mb here because dispatch uses it below */ + if (MB_CUR_MAX > 1 && rl_byte_oriented == 0) + { + if (cxt->pmb[1] == 0) + { + cxt->mb[0] = cxt->lastc; /* == cxt->prevc */ + cxt->mb[1] = '\0'; + } + else + memcpy (cxt->mb, cxt->pmb, sizeof (cxt->mb)); + } +#endif + cxt->prevc = 0; + } + } + + /* The characters in isearch_terminators (set from the user-settable + variable isearch-terminators) are used to terminate the search but + not subsequently execute the character as a command. The default + value is "\033\012" (ESC and C-J). */ + if (cxt->lastc > 0 && strchr (cxt->search_terminators, cxt->lastc)) + { + /* ESC still terminates the search, but if there is pending + input or if input arrives within 0.1 seconds (on systems + with select(2)) it is used as a prefix character + with rl_execute_next. WATCH OUT FOR THIS! This is intended + to allow the arrow keys to be used like ^F and ^B are used + to terminate the search and execute the movement command. + XXX - since _rl_input_available depends on the application- + settable keyboard timeout value, this could alternatively + use _rl_input_queued(100000) */ + if (cxt->lastc == ESC && _rl_input_available ()) + rl_execute_next (ESC); + return (0); + } + +#if defined (HANDLE_MULTIBYTE) + if (MB_CUR_MAX > 1 && rl_byte_oriented == 0) + { + if (cxt->lastc >= 0 && (cxt->mb[0] && cxt->mb[1] == '\0') && ENDSRCH_CHAR (cxt->lastc)) + { + /* This sets rl_pending_input to LASTC; it will be picked up the next + time rl_read_key is called. */ + rl_execute_next (cxt->lastc); + return (0); + } + } + else +#endif + if (cxt->lastc >= 0 && ENDSRCH_CHAR (cxt->lastc)) + { + /* This sets rl_pending_input to LASTC; it will be picked up the next + time rl_read_key is called. */ + rl_execute_next (cxt->lastc); + return (0); + } + + /* Now dispatch on the character. `Opcodes' affect the search string or + state. Other characters are added to the string. */ + switch (cxt->lastc) + { + /* search again */ + case -1: + if (cxt->search_string_index == 0) + { + if (last_isearch_string) + { + cxt->search_string_size = 64 + last_isearch_string_len; + cxt->search_string = (char *)xrealloc (cxt->search_string, cxt->search_string_size); + strcpy (cxt->search_string, last_isearch_string); + cxt->search_string_index = last_isearch_string_len; + rl_display_search (cxt->search_string, (cxt->sflags & SF_REVERSE), -1); + break; + } + return (1); + } + else if (cxt->sflags & SF_REVERSE) + cxt->sline_index--; + else if (cxt->sline_index != cxt->sline_len) + cxt->sline_index++; + else + rl_ding (); + break; + + /* switch directions */ + case -2: + cxt->direction = -cxt->direction; + if (cxt->direction < 0) + cxt->sflags |= SF_REVERSE; + else + cxt->sflags &= ~SF_REVERSE; + break; + + /* delete character from search string. */ + case -3: /* C-H, DEL */ + /* This is tricky. To do this right, we need to keep a + stack of search positions for the current search, with + sentinels marking the beginning and end. But this will + do until we have a real isearch-undo. */ + if (cxt->search_string_index == 0) + rl_ding (); + else + cxt->search_string[--cxt->search_string_index] = '\0'; + break; + + case -4: /* C-G, abort */ + rl_replace_line (cxt->lines[cxt->save_line], 0); + rl_point = cxt->save_point; + rl_mark = cxt->save_mark; + rl_restore_prompt(); + rl_clear_message (); + + return -1; + + case -5: /* C-W */ + /* skip over portion of line we already matched and yank word */ + wstart = rl_point + cxt->search_string_index; + if (wstart >= rl_end) + { + rl_ding (); + break; + } + + /* if not in a word, move to one. */ + cval = _rl_char_value (rl_line_buffer, wstart); + if (_rl_walphabetic (cval) == 0) + { + rl_ding (); + break; + } + n = MB_NEXTCHAR (rl_line_buffer, wstart, 1, MB_FIND_NONZERO);; + while (n < rl_end) + { + cval = _rl_char_value (rl_line_buffer, n); + if (_rl_walphabetic (cval) == 0) + break; + n = MB_NEXTCHAR (rl_line_buffer, n, 1, MB_FIND_NONZERO);; + } + wlen = n - wstart + 1; + if (cxt->search_string_index + wlen + 1 >= cxt->search_string_size) + { + cxt->search_string_size += wlen + 1; + cxt->search_string = (char *)xrealloc (cxt->search_string, cxt->search_string_size); + } + for (; wstart < n; wstart++) + cxt->search_string[cxt->search_string_index++] = rl_line_buffer[wstart]; + cxt->search_string[cxt->search_string_index] = '\0'; + break; + + case -6: /* C-Y */ + /* skip over portion of line we already matched and yank rest */ + wstart = rl_point + cxt->search_string_index; + if (wstart >= rl_end) + { + rl_ding (); + break; + } + n = rl_end - wstart + 1; + if (cxt->search_string_index + n + 1 >= cxt->search_string_size) + { + cxt->search_string_size += n + 1; + cxt->search_string = (char *)xrealloc (cxt->search_string, cxt->search_string_size); + } + for (n = wstart; n < rl_end; n++) + cxt->search_string[cxt->search_string_index++] = rl_line_buffer[n]; + cxt->search_string[cxt->search_string_index] = '\0'; + break; + + /* Add character to search string and continue search. */ + default: + if (cxt->search_string_index + 2 >= cxt->search_string_size) + { + cxt->search_string_size += 128; + cxt->search_string = (char *)xrealloc (cxt->search_string, cxt->search_string_size); + } +#if defined (HANDLE_MULTIBYTE) + if (MB_CUR_MAX > 1 && rl_byte_oriented == 0) + { + int j, l; + + if (cxt->mb[0] == 0 || cxt->mb[1] == 0) + cxt->search_string[cxt->search_string_index++] = cxt->mb[0]; + else + for (j = 0, l = RL_STRLEN (cxt->mb); j < l; ) + cxt->search_string[cxt->search_string_index++] = cxt->mb[j++]; + } + else +#endif + cxt->search_string[cxt->search_string_index++] = cxt->lastc; /* XXX - was c instead of lastc */ + cxt->search_string[cxt->search_string_index] = '\0'; + break; + } + + for (cxt->sflags &= ~(SF_FOUND|SF_FAILED);; ) + { + limit = cxt->sline_len - cxt->search_string_index + 1; + + /* Search the current line. */ + while ((cxt->sflags & SF_REVERSE) ? (cxt->sline_index >= 0) : (cxt->sline_index < limit)) + { + if (STREQN (cxt->search_string, cxt->sline + cxt->sline_index, cxt->search_string_index)) + { + cxt->sflags |= SF_FOUND; + break; + } + else + cxt->sline_index += cxt->direction; + } + if (cxt->sflags & SF_FOUND) + break; + + /* Move to the next line, but skip new copies of the line + we just found and lines shorter than the string we're + searching for. */ + do + { + /* Move to the next line. */ + cxt->history_pos += cxt->direction; + + /* At limit for direction? */ + if ((cxt->sflags & SF_REVERSE) ? (cxt->history_pos < 0) : (cxt->history_pos == cxt->hlen)) + { + cxt->sflags |= SF_FAILED; + break; + } + + /* We will need these later. */ + cxt->sline = cxt->lines[cxt->history_pos]; + cxt->sline_len = strlen (cxt->sline); + } + while ((cxt->prev_line_found && STREQ (cxt->prev_line_found, cxt->lines[cxt->history_pos])) || + (cxt->search_string_index > cxt->sline_len)); + + if (cxt->sflags & SF_FAILED) + break; + + /* Now set up the line for searching... */ + cxt->sline_index = (cxt->sflags & SF_REVERSE) ? cxt->sline_len - cxt->search_string_index : 0; + } + + if (cxt->sflags & SF_FAILED) + { + /* We cannot find the search string. Ding the bell. */ + rl_ding (); + cxt->history_pos = cxt->last_found_line; + return 1; + } + + /* We have found the search string. Just display it. But don't + actually move there in the history list until the user accepts + the location. */ + if (cxt->sflags & SF_FOUND) + { + cxt->prev_line_found = cxt->lines[cxt->history_pos]; + rl_replace_line (cxt->lines[cxt->history_pos], 0); + rl_point = cxt->sline_index; + cxt->last_found_line = cxt->history_pos; + rl_display_search (cxt->search_string, (cxt->sflags & SF_REVERSE), (cxt->history_pos == cxt->save_line) ? -1 : cxt->history_pos); + } + + return 1; +} + +static int +_rl_isearch_cleanup (cxt, r) + _rl_search_cxt *cxt; + int r; +{ + if (r >= 0) + _rl_isearch_fini (cxt); + _rl_scxt_dispose (cxt, 0); + _rl_iscxt = 0; + + RL_UNSETSTATE(RL_STATE_ISEARCH); + + return (r != 0); +} + +/* Search through the history looking for an interactively typed string. + This is analogous to i-search. We start the search in the current line. + DIRECTION is which direction to search; >= 0 means forward, < 0 means + backwards. */ +static int +rl_search_history (direction, invoking_key) + int direction, invoking_key; +{ + _rl_search_cxt *cxt; /* local for now, but saved globally */ + int c, r; + + RL_SETSTATE(RL_STATE_ISEARCH); + cxt = _rl_isearch_init (direction); + + rl_display_search (cxt->search_string, (cxt->sflags & SF_REVERSE), -1); + + /* If we are using the callback interface, all we do is set up here and + return. The key is that we leave RL_STATE_ISEARCH set. */ + if (RL_ISSTATE (RL_STATE_CALLBACK)) + return (0); + + r = -1; + for (;;) + { + c = _rl_search_getchar (cxt); + /* We might want to handle EOF here (c == 0) */ + r = _rl_isearch_dispatch (cxt, cxt->lastc); + if (r <= 0) + break; + } + + /* The searching is over. The user may have found the string that she + was looking for, or else she may have exited a failing search. If + LINE_INDEX is -1, then that shows that the string searched for was + not found. We use this to determine where to place rl_point. */ + return (_rl_isearch_cleanup (cxt, r)); +} + +#if defined (READLINE_CALLBACKS) +/* Called from the callback functions when we are ready to read a key. The + callback functions know to call this because RL_ISSTATE(RL_STATE_ISEARCH). + If _rl_isearch_dispatch finishes searching, this function is responsible + for turning off RL_STATE_ISEARCH, which it does using _rl_isearch_cleanup. */ +int +_rl_isearch_callback (cxt) + _rl_search_cxt *cxt; +{ + int c, r; + + c = _rl_search_getchar (cxt); + /* We might want to handle EOF here */ + r = _rl_isearch_dispatch (cxt, cxt->lastc); + + return (r <= 0) ? _rl_isearch_cleanup (cxt, r) : 0; +} +#endif diff --git a/lib/readline/rldefs.h b/lib/readline/rldefs.h index 025775466..f4148f9c0 100644 --- a/lib/readline/rldefs.h +++ b/lib/readline/rldefs.h @@ -2,7 +2,7 @@ for readline. This should be included after any files that define system-specific constants like _POSIX_VERSION or USG. */ -/* Copyright (C) 1987-2009 Free Software Foundation, Inc. +/* Copyright (C) 1987-2011 Free Software Foundation, Inc. This file is part of the GNU Readline Library (Readline), a library for reading lines of text with interactive input and history editing. @@ -148,6 +148,10 @@ extern char *_rl_strpbrk PARAMS((const char *, const char *)); : ((a)[0] == (b)[0]) && (strncmp ((a), (b), (n)) == 0)) #endif +#if !defined (RL_STRLEN) +# define RL_STRLEN(s) (((s) && (s)[0]) ? ((s)[1] ? ((s)[2] ? strlen(s) : 2) : 1) : 0) +#endif + #if !defined (FREE) # define FREE(x) if (x) free (x) #endif diff --git a/lib/readline/rlprivate.h b/lib/readline/rlprivate.h index f39c462a6..535696916 100644 --- a/lib/readline/rlprivate.h +++ b/lib/readline/rlprivate.h @@ -90,6 +90,7 @@ typedef struct __rl_search_context int lastc; #if defined (HANDLE_MULTIBYTE) char mb[MB_LEN_MAX]; + char pmb[MB_LEN_MAX]; #endif char *sline; diff --git a/lib/readline/signals.c b/lib/readline/signals.c index b34002fd1..6b59b7281 100644 --- a/lib/readline/signals.c +++ b/lib/readline/signals.c @@ -146,15 +146,7 @@ static RETSIGTYPE rl_signal_handler (sig) int sig; { -#if 0 -#if defined (SIGWINCH) - if (_rl_interrupt_immediately || (sig != SIGWINCH && RL_ISSTATE(RL_STATE_CALLBACK))) -#else - if (_rl_interrupt_immediately || RL_ISSTATE(RL_STATE_CALLBACK)) -#endif -#else if (_rl_interrupt_immediately) -#endif { _rl_interrupt_immediately = 0; _rl_handle_signal (sig); diff --git a/lib/readline/signals.c~ b/lib/readline/signals.c~ index ba2674ab4..b34002fd1 100644 --- a/lib/readline/signals.c~ +++ b/lib/readline/signals.c~ @@ -146,7 +146,15 @@ static RETSIGTYPE rl_signal_handler (sig) int sig; { +#if 0 +#if defined (SIGWINCH) + if (_rl_interrupt_immediately || (sig != SIGWINCH && RL_ISSTATE(RL_STATE_CALLBACK))) +#else if (_rl_interrupt_immediately || RL_ISSTATE(RL_STATE_CALLBACK)) +#endif +#else + if (_rl_interrupt_immediately) +#endif { _rl_interrupt_immediately = 0; _rl_handle_signal (sig); diff --git a/lib/sh/zread.c b/lib/sh/zread.c index 0fd1199ed..5db21a986 100644 --- a/lib/sh/zread.c +++ b/lib/sh/zread.c @@ -160,14 +160,13 @@ void zsyncfd (fd) int fd; { - off_t off; - int r; + off_t off, r; off = lused - lind; r = 0; if (off > 0) r = lseek (fd, -off, SEEK_CUR); - if (r >= 0) + if (r != -1) lused = lind = 0; } diff --git a/lib/sh/zread.c~ b/lib/sh/zread.c~ new file mode 100644 index 000000000..9a3dbd6e2 --- /dev/null +++ b/lib/sh/zread.c~ @@ -0,0 +1,172 @@ +/* zread - read data from file descriptor into buffer with retries */ + +/* Copyright (C) 1999-2002 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 3 of the License, 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. If not, see . +*/ + +#include + +#include + +#if defined (HAVE_UNISTD_H) +# include +#endif + +#include + +#if !defined (errno) +extern int errno; +#endif + +#ifndef SEEK_CUR +# define SEEK_CUR 1 +#endif + +/* Read LEN bytes from FD into BUF. Retry the read on EINTR. Any other + error causes the loop to break. */ +ssize_t +zread (fd, buf, len) + int fd; + char *buf; + size_t len; +{ + ssize_t r; + + while ((r = read (fd, buf, len)) < 0 && errno == EINTR) + ; + return r; +} + +/* Read LEN bytes from FD into BUF. Retry the read on EINTR, up to three + interrupts. Any other error causes the loop to break. */ + +#ifdef NUM_INTR +# undef NUM_INTR +#endif +#define NUM_INTR 3 + +ssize_t +zreadretry (fd, buf, len) + int fd; + char *buf; + size_t len; +{ + ssize_t r; + int nintr; + + for (nintr = 0; ; ) + { + r = read (fd, buf, len); + if (r >= 0) + return r; + if (r == -1 && errno == EINTR) + { + if (++nintr >= NUM_INTR) + return -1; + continue; + } + return r; + } +} + +/* Call read(2) and allow it to be interrupted. Just a stub for now. */ +ssize_t +zreadintr (fd, buf, len) + int fd; + char *buf; + size_t len; +{ + return (read (fd, buf, len)); +} + +/* Read one character from FD and return it in CP. Return values are as + in read(2). This does some local buffering to avoid many one-character + calls to read(2), like those the `read' builtin performs. */ + +static char lbuf[128]; +static size_t lind, lused; + +ssize_t +zreadc (fd, cp) + int fd; + char *cp; +{ + ssize_t nr; + + if (lind == lused || lused == 0) + { + nr = zread (fd, lbuf, sizeof (lbuf)); + lind = 0; + if (nr <= 0) + { + lused = 0; + return nr; + } + lused = nr; + } + if (cp) + *cp = lbuf[lind++]; + return 1; +} + +/* Don't mix calls to zreadc and zreadcintr in the same function, since they + use the same local buffer. */ +ssize_t +zreadcintr (fd, cp) + int fd; + char *cp; +{ + ssize_t nr; + + if (lind == lused || lused == 0) + { + nr = zreadintr (fd, lbuf, sizeof (lbuf)); + lind = 0; + if (nr <= 0) + { + lused = 0; + return nr; + } + lused = nr; + } + if (cp) + *cp = lbuf[lind++]; + return 1; +} + +void +zreset () +{ + lind = lused = 0; +} + +/* Sync the seek pointer for FD so that the kernel's idea of the last char + read is the last char returned by zreadc. */ +void +zsyncfd (fd) + int fd; +{ + off_t off, r; + + off = lused - lind; + r = 0; + if (off > 0) + r = lseek (fd, -off, SEEK_CUR); + + if (r >= 0) + lused = lind = 0; +} diff --git a/tests/COPYRIGHT b/tests/COPYRIGHT index 57d472109..43b39df61 100644 --- a/tests/COPYRIGHT +++ b/tests/COPYRIGHT @@ -3,4 +3,7 @@ Unless otherwise stated, all files in this directory are Copyright (C) 2004,2005,2006,2007,2008,2009,2010,2011 Free Software Foundation, Inc. +See the file COPYING in the bash distribution root directory for copying +and usage restrictions. + The file ifs-posix.tests is Copyright (C) 2005 Glen Fowler. diff --git a/tests/RUN-ONE-TEST b/tests/RUN-ONE-TEST index 3efcf32d6..72ec06a2c 100755 --- a/tests/RUN-ONE-TEST +++ b/tests/RUN-ONE-TEST @@ -1,4 +1,4 @@ -BUILD_DIR=/usr/local/build/chet/bash/bash-current +BUILD_DIR=/usr/local/build/bash/bash-current THIS_SH=$BUILD_DIR/bash PATH=$PATH:$BUILD_DIR diff --git a/tests/RUN-ONE-TEST~ b/tests/RUN-ONE-TEST~ new file mode 100755 index 000000000..3efcf32d6 --- /dev/null +++ b/tests/RUN-ONE-TEST~ @@ -0,0 +1,9 @@ +BUILD_DIR=/usr/local/build/chet/bash/bash-current +THIS_SH=$BUILD_DIR/bash +PATH=$PATH:$BUILD_DIR + +export THIS_SH PATH + +rm -f /tmp/xx + +/bin/sh "$@"