From b88cd1c366a325d537e59e310fd6410d8084df21 Mon Sep 17 00:00:00 2001 From: Chet Ramey Date: Thu, 18 Sep 2025 17:26:51 -0400 Subject: [PATCH] experimental change to use groff instead of man2html for HTML man pages; man page updates for reserved words; fix for pattern matching bracket expression ranges; readline changes to disallow defining some recursive keyboard macros --- CWRU/CWRU.chlog | 51 + builtins/bashgetopt.c | 2 +- builtins/declare.def | 20 +- builtins/evalfile.c | 2 +- builtins/evalstring.c | 10 +- builtins/mkbuiltins.c | 92 +- doc/Makefile.in | 5 +- doc/bash.0 | 6401 ++++---- doc/bash.1 | 129 +- doc/bash.html | 30477 +++++++++++++++++++------------------- doc/bash.info | 478 +- doc/bashref.html | 183 +- doc/bashref.info | 478 +- doc/bashref.texi | 120 +- doc/htmlpost.sh | 20 +- doc/version.texi | 6 +- eval.c | 2 +- execute_cmd.c | 42 +- execute_cmd.h | 2 +- jobs.c | 2 + lib/glob/smatch.c | 2 +- lib/readline/macro.c | 6 +- lib/readline/readline.c | 4 +- lib/readline/text.c | 6 +- 24 files changed, 19070 insertions(+), 19470 deletions(-) diff --git a/CWRU/CWRU.chlog b/CWRU/CWRU.chlog index 7cb586b19..6c73a4fc7 100644 --- a/CWRU/CWRU.chlog +++ b/CWRU/CWRU.chlog @@ -11683,3 +11683,54 @@ lib/readline/signals.c call rl_message. That takes care of the case where redisplay gets a SIGINT while `blocking' it. Report from Grisha Levit + +jobs.c + - print_pipeline: make sure we separate the fatal signal description + from the pipeline command by at least one space + + 9/6 + --- +doc/Makefile.in + - MAN2HTML: experimental change to use `groff -Thtml -man' to + generate HTML versions of man pages instead of man2html + +doc/bash.1,doc/bashref.texi + - reserved words: add clarifying language about when reserved words + are recognized + - lists: modify description to define lists as sequences of and-or + lists; clarify list terminators + - select: update synopsis to indicate a word list and optional + semicolon like `for' + - case: rearrange description to introduce pattern lists and expand + the definition of a case clause to include the terminator, which + is optional for the last clause + From a report by Martin D Kealey + + 9/8 + --- +lib/glob/smatch.c + - charcmp_wc: don't restrict codepoints to 0..UCHAR_MAX; this will + eventually break with multibyte character codepoints + From a report from Duncan Roe ; fix + suggested by Grisha Levit + + 9/11 + ---- +[prayers for the victims of 9/11/2001] + +lib/readline/macro.c + - rl_start_kbd_macro: don't allow keyboard macro definitions while + reading input from a bound macro. + Suggested by Grisha Levit + +lib/readline/readline.c,lib/readline/text.c + - _rl_dispatch_subseq,_rl_insert_next,_rl_char_search: if we're + defining a keyboard macro, don't insert the expanded value of a + macro that is bound to a key sequence added to the keyboard macro + Report and patch from Grisha Levit + + 9/12 + ---- +builtins/mkbuiltins.c + - some minor code cleanups + Patch from Martin D Kealey diff --git a/builtins/bashgetopt.c b/builtins/bashgetopt.c index 92c015592..db078d8ed 100644 --- a/builtins/bashgetopt.c +++ b/builtins/bashgetopt.c @@ -35,7 +35,7 @@ #define ISOPT(s) (((*(s) == '-') || (plus && *(s) == '+')) && (s)[1]) #define NOTOPT(s) (((*(s) != '-') && (!plus || *(s) != '+')) || (s)[1] == '\0') - + static int sp; char *list_optarg; diff --git a/builtins/declare.def b/builtins/declare.def index 6d44c348d..a8284daac 100644 --- a/builtins/declare.def +++ b/builtins/declare.def @@ -1,7 +1,7 @@ This file is declare.def, from which is created declare.c. It implements the builtins "declare" and "local" in Bash. -Copyright (C) 1987-2024 Free Software Foundation, Inc. +Copyright (C) 1987-2025 Free Software Foundation, Inc. This file is part of GNU Bash, the Bourne Again SHell. @@ -39,8 +39,10 @@ Options: -p display the attributes and value of each NAME Options which set attributes: +#ifdef ARRAY_VARS -a to make NAMEs indexed arrays (if supported) -A to make NAMEs associative arrays (if supported) +#endif -i to make NAMEs have the `integer' attribute -l to convert the value of each NAME to lower case on assignment -n make NAME a reference to the variable named by its value @@ -131,7 +133,7 @@ local_builtin (WORD_LIST *list) builtin_help (); return (EX_USAGE); } - + if (variable_context) return (declare_internal (list, 1)); else @@ -199,7 +201,7 @@ declare_transform_name (char *name, int flags_on, int flags_off) { SHELL_VAR *var, *v; char *newname; - + var = find_variable (name); if (var == 0) newname = nameref_transform_name (name, ASS_MKLOCAL); @@ -234,7 +236,7 @@ declare_invalid_opts (int flags_on, int flags_off) else if (flags_on & att_array) optchar = "-a"; - sh_invalidopt (optchar); + sh_invalidopt (optchar); return (EXECUTION_FAILURE); } else if ((flags_on & att_assoc) && (flags_off & att_assoc)) @@ -255,7 +257,7 @@ declare_invalid_opts (int flags_on, int flags_off) /* Ineffective, since you can't have namerefs referencing positional parameters */ else if ((flags_on & att_nameref) && (flags_on & att_integer)) { - builtin_error ("cannot use -n with -i"); + builtin_error (_("cannot use -n with -i")); return (EX_BADUSAGE); } @@ -415,7 +417,7 @@ declare_internal (WORD_LIST *list, int local_var) opt = declare_invalid_opts (flags_on, flags_off); if (opt != 0) return (opt); - + #define NEXT_VARIABLE() free (name); list = list->next; continue /* There are arguments left, so we are making variables. */ @@ -520,7 +522,7 @@ declare_internal (WORD_LIST *list, int local_var) } else #endif /* DEBUGGER */ - { + { t = nodefs ? name_cell (var) : named_function_string (name, function_cell (var), FUNC_MULTILINE|FUNC_EXTERNAL); printf ("%s\n", t); any_failed = sh_chkwrite (any_failed); @@ -876,7 +878,7 @@ restart_new_var_name: /* Readonly variable error checking. */ - /* Cannot use declare +r to turn off readonly attribute. */ + /* Cannot use declare +r to turn off readonly attribute. */ if (readonly_p (var) && (flags_off & att_readonly)) { sh_readonly (name_cell (var)); @@ -1040,7 +1042,7 @@ restart_new_var_name: sh_invalidid (value); /* what else can cause this to fail? */ else if (flags_on & att_integer) - builtin_error ("%s: expands to invalid variable name for name reference", value); + builtin_error (_("%s: expands to invalid variable name for name reference"), value); assign_error++; /* XXX - unset this variable? or leave it as normal var? */ if (created_var) diff --git a/builtins/evalfile.c b/builtins/evalfile.c index 3026c5f00..ea0a205ae 100644 --- a/builtins/evalfile.c +++ b/builtins/evalfile.c @@ -183,7 +183,7 @@ file_error_and_exit: free (string); return ((flags & FEVAL_BUILTIN) ? EXECUTION_SUCCESS : 1); } - + if ((flags & FEVAL_CHECKBINARY) && check_binary_file (string, (nr > 80) ? 80 : nr)) { diff --git a/builtins/evalstring.c b/builtins/evalstring.c index 2b15b9dd7..a408bbde8 100644 --- a/builtins/evalstring.c +++ b/builtins/evalstring.c @@ -341,10 +341,10 @@ parse_and_execute (char *string, const char *from_file, int flags) if (parser_expanding_alias ()) /* push current shell_input_line */ parser_save_alias (); - + if (lreset == 0) line_number--; - + indirection_level++; code = should_jump_to_top_level = 0; @@ -425,7 +425,7 @@ parse_and_execute (char *string, const char *from_file, int flags) run_unwind_frame ("pe_dispose"); last_result = last_command_exit_value = EXECUTION_FAILURE; /* XXX */ set_pipestatus_from_exit (last_command_exit_value); - + if (subshell_environment) { should_jump_to_top_level = 1; @@ -698,7 +698,7 @@ parse_string (char *string, const char *from_file, int flags, COMMAND **cmdp, ch break; } } - + if (parse_command () == 0) { if (cmdp) @@ -861,6 +861,6 @@ evalstring (char *string, const char *from_file, int flags) sh_longjmp (return_catch, 1); } } - + return (r); } diff --git a/builtins/mkbuiltins.c b/builtins/mkbuiltins.c index c4cacdfc2..b39b9dd55 100644 --- a/builtins/mkbuiltins.c +++ b/builtins/mkbuiltins.c @@ -183,7 +183,7 @@ char *arrayvar_builtins[] = "typeset", "unset", "wait", /*]*/ (char *)NULL }; - + /* Forward declarations. */ static int is_special_builtin (char *); static int is_assignment_builtin (char *); @@ -288,6 +288,8 @@ main (int argc, char **argv) if (include_filename == 0) include_filename = extern_filename; + if (include_filename == 0) + include_filename = "builtext.h"; /* If there are no files to process, just quit now. */ if (arg_index == argc) @@ -328,7 +330,7 @@ main (int argc, char **argv) /* Process the .def files. */ while (arg_index < argc) { - register char *arg; + char *arg; arg = argv[arg_index++]; @@ -399,7 +401,7 @@ array_create (int width) ARRAY * copy_string_array (ARRAY *array) { - register int i; + int i; ARRAY *copy; if (!array) @@ -412,7 +414,7 @@ copy_string_array (ARRAY *array) copy->width = array->width; copy->array = (char **)xmalloc ((1 + array->sindex) * sizeof (char *)); - + for (i = 0; i < array->sindex; i++) copy->array[i] = savestring (array->array[i]); @@ -484,7 +486,7 @@ HANDLER_ENTRY handlers[] = { HANDLER_ENTRY * find_directive (char *directive) { - register int i; + int i; for (i = 0; handlers[i].directive; i++) if (strcmp (handlers[i].directive, directive) == 0) @@ -513,7 +515,7 @@ int output_cpp_line_info = 0; void extract_info (char *filename, FILE *structfile, FILE *externfile) { - register int i; + int i; DEF_FILE *defs; struct stat finfo; size_t file_size; @@ -578,7 +580,7 @@ extract_info (char *filename, FILE *structfile, FILE *externfile) if (*line == '$') { - register int j; + int j; char *directive; HANDLER_ENTRY *handler; @@ -653,7 +655,7 @@ extract_info (char *filename, FILE *structfile, FILE *externfile) static void free_builtin (BUILTIN_DESC *builtin) { - register int i; + int i; free_safely (builtin->name); free_safely (builtin->function); @@ -675,8 +677,8 @@ free_builtin (BUILTIN_DESC *builtin) void free_defs (DEF_FILE *defs) { - register int i; - register BUILTIN_DESC *builtin; + int i; + BUILTIN_DESC *builtin; if (defs->production) free (defs->production); @@ -718,7 +720,7 @@ strip_whitespace (char *string) void remove_trailing_whitespace (char *string) { - register int i; + int i; i = strlen (string) - 1; @@ -769,7 +771,7 @@ current_builtin (char *directive, DEF_FILE *defs) void add_documentation (DEF_FILE *defs, char *line) { - register BUILTIN_DESC *builtin; + BUILTIN_DESC *builtin; builtin = current_builtin ("(implied LONGDOC)", defs); @@ -837,7 +839,7 @@ builtin_handler (char *self, DEF_FILE *defs, char *arg) int function_handler (char *self, DEF_FILE *defs, char *arg) { - register BUILTIN_DESC *builtin; + BUILTIN_DESC *builtin; builtin = current_builtin (self, defs); @@ -859,7 +861,7 @@ function_handler (char *self, DEF_FILE *defs, char *arg) int docname_handler (char *self, DEF_FILE *defs, char *arg) { - register BUILTIN_DESC *builtin; + BUILTIN_DESC *builtin; builtin = current_builtin (self, defs); @@ -876,7 +878,7 @@ docname_handler (char *self, DEF_FILE *defs, char *arg) int short_doc_handler (char *self, DEF_FILE *defs, char *arg) { - register BUILTIN_DESC *builtin; + BUILTIN_DESC *builtin; builtin = current_builtin (self, defs); @@ -900,7 +902,7 @@ comment_handler (char *self, DEF_FILE *defs, char *arg) int depends_on_handler (char *self, DEF_FILE *defs, char *arg) { - register BUILTIN_DESC *builtin; + BUILTIN_DESC *builtin; char *dependent; builtin = current_builtin (self, defs); @@ -1077,7 +1079,7 @@ char *structfile_header[] = { "/* This file is manufactured by ./mkbuiltins, and should not be", " edited by hand. See the source to mkbuiltins for details. */", "", - "/* Copyright (C) 1987-2022 Free Software Foundation, Inc.", + "/* Copyright (C) 1987-2025 Free Software Foundation, Inc.", "", " This file is part of GNU Bash, the Bourne Again SHell.", "", @@ -1130,16 +1132,14 @@ char *structfile_footer[] = { void write_file_headers (FILE *structfile, FILE *externfile) { - register int i; + int i; if (structfile) { for (i = 0; structfile_header[i]; i++) fprintf (structfile, "%s\n", structfile_header[i]); - fprintf (structfile, "#include \"%s\"\n", - include_filename ? include_filename : "builtext.h"); - + fprintf (structfile, "#include \"%s\"\n", include_filename); fprintf (structfile, "#include \"bashintl.h\"\n"); fprintf (structfile, "\nstruct builtin static_shell_builtins[] = {\n"); @@ -1147,8 +1147,7 @@ write_file_headers (FILE *structfile, FILE *externfile) if (externfile) fprintf (externfile, - "/* %s - The list of builtins found in libbuiltins.a. */\n", - include_filename ? include_filename : "builtext.h"); + "/* %s - The list of builtins found in libbuiltins.a. */\n", include_filename); } /* Write out any necessary closing information for @@ -1156,7 +1155,7 @@ write_file_headers (FILE *structfile, FILE *externfile) void write_file_footers (FILE *structfile, FILE *externfile) { - register int i; + int i; /* Write out the footers. */ if (structfile) @@ -1171,12 +1170,12 @@ write_file_footers (FILE *structfile, FILE *externfile) void write_builtins (DEF_FILE *defs, FILE *structfile, FILE *externfile) { - register int i; + int i; /* Write out the information. */ if (defs->builtins) { - register BUILTIN_DESC *builtin; + BUILTIN_DESC *builtin; for (i = 0; i < defs->builtins->sindex; i++) { @@ -1275,8 +1274,8 @@ write_builtins (DEF_FILE *defs, FILE *structfile, FILE *externfile) void write_longdocs (FILE *stream, ARRAY *builtins) { - register int i; - register BUILTIN_DESC *builtin; + int i; + BUILTIN_DESC *builtin; char *dname; char *sarray[2]; @@ -1312,7 +1311,7 @@ write_longdocs (FILE *stream, ARRAY *builtins) void write_dummy_declarations (FILE *stream, ARRAY *builtins) { - register int i; + int i; BUILTIN_DESC *builtin; for (i = 0; structfile_header[i]; i++) @@ -1336,7 +1335,7 @@ write_dummy_declarations (FILE *stream, ARRAY *builtins) void write_ifdefs (FILE *stream, char **defines) { - register int i; + int i; if (!stream) return; @@ -1365,7 +1364,7 @@ write_ifdefs (FILE *stream, char **defines) void write_endifs (FILE *stream, char **defines) { - register int i; + int i; if (!stream) return; @@ -1390,8 +1389,8 @@ write_endifs (FILE *stream, char **defines) void write_documentation (FILE *stream, char **documentation, int indentation, int flags) { - register int i, j; - register char *line; + int i, j; + char *line; int string_array, texinfo, base_indent, filename_p; if (stream == 0) @@ -1456,16 +1455,9 @@ write_documentation (FILE *stream, char **documentation, int indentation, int fl { for (j = 0; line[j]; j++) { - switch (line[j]) - { - case '\\': - case '"': - fprintf (stream, "\\%c", line[j]); - break; - - default: - fprintf (stream, "%c", line[j]); - } + if (line[j] == '\\' || line[j] == '"') + fputc ('\\', stream); + fputc (line[j], stream); } /* closing right paren for gettext */ @@ -1489,14 +1481,12 @@ write_documentation (FILE *stream, char **documentation, int indentation, int fl case '@': case '{': case '}': - fprintf (stream, "@%c", line[j]); + fputc ('@', stream); break; - - default: - fprintf (stream, "%c", line[j]); } + fputc (line[j], stream); } - fprintf (stream, "\n"); + fputc ('\n', stream); } else fprintf (stream, "%s\n", line); @@ -1554,12 +1544,12 @@ write_helpfiles (ARRAY *builtins) free (helpfile); } return 0; -} - +} + static int _find_in_table (char *name, char **name_table) { - register int i; + int i; for (i = 0; name_table[i]; i++) if (strcmp (name, name_table[i]) == 0) diff --git a/doc/Makefile.in b/doc/Makefile.in index b8ac13fc3..e0e2a15b1 100644 --- a/doc/Makefile.in +++ b/doc/Makefile.in @@ -68,7 +68,8 @@ RL_LIBDIR = $(topdir)/lib/readline MAKEINFO = makeinfo TEXI2DVI = ${SUPPORT_SRCDIR}/texi2dvi TEXI2HTML = ${SUPPORT_SRCDIR}/texi2html -MAN2HTML = ${BUILD_DIR}/support/man2html +#MAN2HTML = ${BUILD_DIR}/support/man2html +MAN2HTML = ${GROFF} -Thtml -man HTMLPOST = ${srcdir}/htmlpost.sh QUIETPS = #set this to -q to shut up dvips PAPERSIZE = letter # change to a4 for A4-size paper @@ -153,7 +154,7 @@ BASHREF_FILES = $(srcdir)/bashref.texi $(srcdir)/fdl.texi $(srcdir)/version.texi # $(RM) $@ # -${TEXI2PDF} $< -all: info dvi text html pdf $(MAN2HTML) +all: info dvi text html pdf # $(MAN2HTML) nodvi: ps info text html everything: all ps diff --git a/doc/bash.0 b/doc/bash.0 index 218066f86..ee493f1d4 100644 --- a/doc/bash.0 +++ b/doc/bash.0 @@ -250,10 +250,24 @@ DDEEFFIINNIITTIIOONNSS RREESSEERRVVEEDD WWOORRDDSS _R_e_s_e_r_v_e_d _w_o_r_d_s 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 command (see SSHHEELLLL GGRRAAMMMMAARR below), the third word of a - ccaassee or sseelleecctt command (only iinn is valid), or the third word of a ffoorr - command (only iinn and ddoo are valid): + following words are recognized as reserved when unquoted and either + + +o the first word of a command (see SSHHEELLLL GGRRAAMMMMAARR below); + + +o the first word following a reserved word other than ccaassee, ffoorr, + sseelleecctt, or iinn; + + +o the third word of a ccaassee command (only iinn is valid); + + +o the third word of a ffoorr or sseelleecctt command (only iinn and ddoo are + valid); + + +o following a control operator. + + The shell will also recognize reserved words where the syntax of a com- + mand specifically requires the reserved word as the only correct token. + + The following are reserved words: !! ccaassee ccoopprroocc ddoo ddoonnee eelliiff eellssee eessaacc ffii ffoorr ffuunnccttiioonn iiff iinn sseelleecctt tthheenn uunnttiill wwhhiillee {{ }} ttiimmee [[[[ ]]]] @@ -318,27 +332,15 @@ SSHHEELLLL GGRRAAMMMMAARR the last element of a pipeline may be run by the shell process. LLiissttss - A _l_i_s_t is a sequence of one or more pipelines separated by one of the - operators ;;, &&, &&&&, or ||||, and optionally terminated by one of ;;, &&, or - <>. - - Of these list operators, &&&& and |||| have equal precedence, followed by ;; - and &&, which have equal precedence. - - A sequence of one or more newlines may appear in a _l_i_s_t instead of a - semicolon to delimit commands. - - If a command is terminated by the control operator &&, the shell exe- - cutes the command in the _b_a_c_k_g_r_o_u_n_d in a subshell. The shell does not - wait for the command to finish, and the return status is 0. These are - referred to as _a_s_y_n_c_h_r_o_n_o_u_s commands. Commands separated by a ;; are - executed sequentially; the shell waits for each command to terminate in - turn. The return status is the exit status of the last command exe- - cuted. + A _l_i_s_t is a sequence of one or more AND or OR lists separated by one of + the operators ;;, &&, or <>, and optionally terminated by one of + those three characters. AND and OR lists are sequences of one or more pipelines separated by the &&&& and |||| control operators, respectively. AND and OR lists are - executed with left associativity. An AND list has the form + executed with left associativity. + + An AND list has the form _c_o_m_m_a_n_d_1 &&&& _c_o_m_m_a_n_d_2 @@ -353,104 +355,120 @@ SSHHEELLLL GGRRAAMMMMAARR status. The return status of AND and OR lists is the exit status of the last command executed in the list. + Of these list operators, &&&& and |||| have equal precedence, followed by ;; + and &&, which have equal precedence. + + A sequence of one or more newlines may appear in a _l_i_s_t instead of a + semicolon to delimit commands. + + If a command is terminated by the control operator &&, the shell exe- + cutes the command in the _b_a_c_k_g_r_o_u_n_d in a subshell. The shell does not + wait for the command to finish, and the return status is 0. These are + referred to as _a_s_y_n_c_h_r_o_n_o_u_s commands. Commands separated or terminated + by ;; (or an equivalent <>) are executed sequentially; the shell + waits for each command to terminate in turn. + + The return status of a list is the exit status of the last command exe- + cuted. + CCoommppoouunndd CCoommmmaannddss - A _c_o_m_p_o_u_n_d _c_o_m_m_a_n_d is one of the following. In most cases a _l_i_s_t 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 + A _c_o_m_p_o_u_n_d _c_o_m_m_a_n_d is one of the following. In most cases a _l_i_s_t 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. - (_l_i_s_t) _l_i_s_t is executed in a subshell (see CCOOMMMMAANNDD EEXXEECCUUTTIIOONN EENNVVIIRROONN-- - MMEENNTT below for a description of a subshell environment). Vari- - able assignments and builtin commands that affect the shell's + (_l_i_s_t) _l_i_s_t is executed in a subshell (see CCOOMMMMAANNDD EEXXEECCUUTTIIOONN EENNVVIIRROONN-- + MMEENNTT below for a description of a subshell environment). Vari- + able 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 _l_i_s_t. { _l_i_s_t; } _l_i_s_t is executed in the current shell environment. _l_i_s_t must be - terminated with a newline or semicolon. This is known as a + terminated with a newline or semicolon. This is known as a _g_r_o_u_p _c_o_m_m_a_n_d. The return status is the exit status of _l_i_s_t. - Note that unlike the metacharacters (( and )), {{ and }} are _r_e_- - _s_e_r_v_e_d _w_o_r_d_s 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 _l_i_s_t by whitespace or another shell + Note that unlike the metacharacters (( and )), {{ and }} are _r_e_- + _s_e_r_v_e_d _w_o_r_d_s 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 _l_i_s_t by whitespace or another shell metacharacter. ((_e_x_p_r_e_s_s_i_o_n)) - The arithmetic _e_x_p_r_e_s_s_i_o_n is evaluated according to the rules - described below under AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN. If the value of - the expression is non-zero, the return status is 0; otherwise - the return status is 1. The _e_x_p_r_e_s_s_i_o_n undergoes the same ex- - pansions as if it were within double quotes, but unescaped dou- + The arithmetic _e_x_p_r_e_s_s_i_o_n is evaluated according to the rules + described below under AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN. If the value of + the expression is non-zero, the return status is 0; otherwise + the return status is 1. The _e_x_p_r_e_s_s_i_o_n undergoes the same ex- + pansions as if it were within double quotes, but unescaped dou- ble quote characters in _e_x_p_r_e_s_s_i_o_n are not treated specially and are removed. Since this can potentially result in empty - strings, this command treats those as expressions that evaluate + strings, this command treats those as expressions that evaluate to 0. [[[[ _e_x_p_r_e_s_s_i_o_n ]]]] Evaluate the conditional expression _e_x_p_r_e_s_s_i_o_n and return a sta- - tus of zero (true) or non-zero (false). Expressions are com- + tus of zero (true) or non-zero (false). Expressions are com- posed of the primaries described below under CCOONNDDIITTIIOONNAALL EEXXPPRREESS-- - SSIIOONNSS. The words between the [[[[ and ]]]] do not undergo word - splitting and pathname expansion. The shell performs tilde ex- + SSIIOONNSS. The words between the [[[[ and ]]]] do not undergo word + splitting and pathname expansion. The shell performs tilde ex- pansion, parameter and variable expansion, arithmetic expansion, command substitution, process substitution, and quote removal on - those words. Conditional operators such as --ff must be unquoted + those words. Conditional operators such as --ff must be unquoted to be recognized as primaries. - When used with [[[[, the << and >> operators sort lexicographically + When used with [[[[, the << and >> operators sort lexicographically using the current locale. - When the ==== and !!== operators are used, the string to the right + When the ==== and !!== operators are used, the string to the right of the operator is considered a pattern and matched according to the rules described below under PPaatttteerrnn MMaattcchhiinngg, as if the eexxtt-- gglloobb shell option were enabled. The == operator is equivalent to - ====. If the nnooccaasseemmaattcchh shell option is enabled, the match is - performed without regard to the case of alphabetic characters. - The return value is 0 if the string matches (====) or does not - match (!!==) the pattern, and 1 otherwise. If any part of the - pattern is quoted, the quoted portion is matched as a string: + ====. If the nnooccaasseemmaattcchh shell option is enabled, the match is + performed without regard to the case of alphabetic characters. + The return value is 0 if the string matches (====) or does not + match (!!==) the pattern, and 1 otherwise. If any part of the + pattern is quoted, the quoted portion is matched as a string: every character in the quoted portion matches itself, instead of having any special pattern matching meaning. - An additional binary operator, ==~~, is available, with the same - precedence as ==== and !!==. When it is used, the string to the + An additional binary operator, ==~~, is available, with the same + precedence as ==== and !!==. When it is used, the string to the right of the operator is considered a POSIX extended regular ex- - pression and matched accordingly (using the POSIX _r_e_g_c_o_m_p and - _r_e_g_e_x_e_c interfaces usually described in _r_e_g_e_x(3)). The return - value is 0 if the string matches the pattern, and 1 otherwise. + pression and matched accordingly (using the POSIX _r_e_g_c_o_m_p and + _r_e_g_e_x_e_c interfaces usually described in _r_e_g_e_x(3)). The return + value is 0 if the string matches the pattern, and 1 otherwise. If the regular expression is syntactically incorrect, the condi- tional expression's return value is 2. If the nnooccaasseemmaattcchh shell - option is enabled, the match is performed without regard to the + option is enabled, the match is performed without regard to the case of alphabetic characters. - If any part of the pattern is quoted, the quoted portion is - matched literally, as above. If the pattern is stored in a + If any part of the pattern is quoted, the quoted portion is + matched literally, as above. If the pattern is stored in a shell variable, quoting the variable expansion forces the entire - pattern to be matched literally. Treat bracket expressions in - regular expressions carefully, since normal quoting and pattern + pattern to be matched literally. Treat bracket expressions in + regular expressions carefully, since normal quoting and pattern characters lose their meanings between brackets. - The match succeeds if the pattern matches any part of the + The match succeeds if the pattern matches any part of the string. Anchor the pattern using the ^^ and $$ regular expression operators to force it to match the entire string. - The array variable BBAASSHH__RREEMMAATTCCHH records which parts of the - string matched the pattern. The element of BBAASSHH__RREEMMAATTCCHH with - index 0 contains the portion of the string matching the entire - regular expression. Substrings matched by parenthesized subex- + The array variable BBAASSHH__RREEMMAATTCCHH records which parts of the + string matched the pattern. The element of BBAASSHH__RREEMMAATTCCHH with + index 0 contains the portion of the string matching the entire + regular expression. Substrings matched by parenthesized subex- pressions within the regular expression are saved in the remain- - ing BBAASSHH__RREEMMAATTCCHH indices. The element of BBAASSHH__RREEMMAATTCCHH with in- - dex _n is the portion of the string matching the _nth parenthe- - sized subexpression. BBaasshh sets BBAASSHH__RREEMMAATTCCHH in the global - scope; declaring it as a local variable will lead to unexpected + ing BBAASSHH__RREEMMAATTCCHH indices. The element of BBAASSHH__RREEMMAATTCCHH with in- + dex _n is the portion of the string matching the _nth parenthe- + sized subexpression. BBaasshh sets BBAASSHH__RREEMMAATTCCHH in the global + scope; declaring it as a local variable will lead to unexpected results. - Expressions may be combined using the following operators, + Expressions may be combined using the following operators, listed in decreasing order of precedence: (( _e_x_p_r_e_s_s_i_o_n )) - Returns the value of _e_x_p_r_e_s_s_i_o_n. This may be used to + Returns the value of _e_x_p_r_e_s_s_i_o_n. This may be used to override the normal precedence of operators. !! _e_x_p_r_e_s_s_i_o_n True if _e_x_p_r_e_s_s_i_o_n is false. @@ -460,92 +478,97 @@ SSHHEELLLL GGRRAAMMMMAARR True if either _e_x_p_r_e_s_s_i_o_n_1 or _e_x_p_r_e_s_s_i_o_n_2 is true. The &&&& and |||| operators do not evaluate _e_x_p_r_e_s_s_i_o_n_2 if the value - of _e_x_p_r_e_s_s_i_o_n_1 is sufficient to determine the return value of + of _e_x_p_r_e_s_s_i_o_n_1 is sufficient to determine the return value of the entire conditional expression. ffoorr _n_a_m_e [ [ iinn _w_o_r_d _._._. ] ; ] ddoo _l_i_s_t ; ddoonnee - First, expand The list of words following iinn, generating a list - of items. Then, the variable _n_a_m_e is set to each element of - this list in turn, and _l_i_s_t is executed each time. If the iinn + First, expand the list of words following iinn, generating a list + of items. Then, the variable _n_a_m_e is set to each element of + this list in turn, and _l_i_s_t is executed each time. If the iinn _w_o_r_d is omitted, the ffoorr command executes _l_i_s_t once for each po- - sitional parameter that is set (see PPAARRAAMMEETTEERRSS below). The re- - turn status is the exit status of the last command that exe- + sitional parameter that is set (see PPAARRAAMMEETTEERRSS below). The re- + turn status is the exit status of the last command that exe- cutes. If the expansion of the items following iinn results in an - empty list, no commands are executed, and the return status is + empty list, no commands are executed, and the return status is 0. ffoorr (( _e_x_p_r_1 ; _e_x_p_r_2 ; _e_x_p_r_3 )) [;] ddoo _l_i_s_t ; ddoonnee First, evaluate the arithmetic expression _e_x_p_r_1 according to the - rules described below under AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN. Then, re- + rules described below under AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN. Then, re- peatedly evaluate the arithmetic expression _e_x_p_r_2 until it eval- - uates to zero. Each time _e_x_p_r_2 evaluates to a non-zero value, - execute _l_i_s_t and evaluate the arithmetic expression _e_x_p_r_3. 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 _l_i_s_t - that is executed, or non-zero if any of the expressions is in- + uates to zero. Each time _e_x_p_r_2 evaluates to a non-zero value, + execute _l_i_s_t and evaluate the arithmetic expression _e_x_p_r_3. 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 _l_i_s_t + that is executed, or non-zero if any of the expressions is in- valid. - Use the bbrreeaakk and ccoonnttiinnuuee builtins (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS + Use the bbrreeaakk and ccoonnttiinnuuee builtins (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below) to control loop execution. - sseelleecctt _n_a_m_e [ iinn _w_o_r_d ] ; ddoo _l_i_s_t ; ddoonnee - First, expand the list of words following iinn, generating a list - of items, and print the set of expanded words the standard er- - ror, each preceded by a number. If the iinn _w_o_r_d is omitted, - print the positional parameters (see PPAARRAAMMEETTEERRSS below). sseelleecctt - then displays the PPSS33 prompt and reads a line from the standard + sseelleecctt _n_a_m_e [ [ iinn _w_o_r_d _._._. ] ; ] ddoo _l_i_s_t ; ddoonnee + First, expand the list of words following iinn, generating a list + of items, and print the set of expanded words the standard er- + ror, each preceded by a number. If the iinn _w_o_r_d is omitted, + print the positional parameters (see PPAARRAAMMEETTEERRSS below). sseelleecctt + then displays the PPSS33 prompt and reads a line from the standard input. If the line consists of a number corresponding to one of - the displayed words, then sseelleecctt sets the value of _n_a_m_e to that - word. If the line is empty, sseelleecctt displays the words and - prompt again. If EOF is read, sseelleecctt completes and returns 1. - Any other value sets _n_a_m_e to null. The line read is saved in - the variable RREEPPLLYY. The _l_i_s_t is executed after each selection + the displayed words, then sseelleecctt sets the value of _n_a_m_e to that + word. If the line is empty, sseelleecctt displays the words and + prompt again. If EOF is read, sseelleecctt completes and returns 1. + Any other value sets _n_a_m_e to null. The line read is saved in + the variable RREEPPLLYY. The _l_i_s_t is executed after each selection until a bbrreeaakk command is executed. The exit status of sseelleecctt is the exit status of the last command executed in _l_i_s_t, or zero if no commands were executed. ccaassee _w_o_r_d iinn [ [(] _p_a_t_t_e_r_n [ || _p_a_t_t_e_r_n ] ... ) _l_i_s_t ;; ] ... eessaacc A ccaassee command first expands _w_o_r_d, and tries to match it against - each _p_a_t_t_e_r_n in turn, proceeding from first to last, using the - matching rules described under PPaatttteerrnn MMaattcchhiinngg below. A pat- - tern list is a set of one or more patterns separated by , and - the ) operator terminates the pattern list. The _w_o_r_d is ex- - panded using tilde expansion, parameter and variable expansion, - arithmetic expansion, command substitution, process substitution - and quote removal. Each _p_a_t_t_e_r_n examined is expanded using - tilde expansion, parameter and variable expansion, arithmetic - expansion, command substitution, process substitution, and quote - removal. If the nnooccaasseemmaattcchh shell option is enabled, the match - is performed without regard to the case of alphabetic charac- - ters. A _c_l_a_u_s_e is a pattern list and an associated _l_i_s_t. + each _p_a_t_t_e_r_n in turn, proceeding from first to last, using the + matching rules described under PPaatttteerrnn MMaattcchhiinngg below. The _w_o_r_d + is expanded using tilde expansion, parameter and variable expan- + sion, arithmetic expansion, command substitution, process sub- + stitution and quote removal. Each _p_a_t_t_e_r_n examined is expanded + using tilde expansion, parameter and variable expansion, arith- + metic expansion, command substitution, process substitution, and + quote removal. If the nnooccaasseemmaattcchh shell option is enabled, the + match is performed without regard to the case of alphabetic + characters. + + A _p_a_t_t_e_r_n _l_i_s_t is a set of one or more patterns separated by ||, + and terminated by the )) operator. A case _c_l_a_u_s_e is a pattern + list and an associated _l_i_s_t, terminated by ;;;;, ;;&&, or ;;;;&&. The + terminator is optional for the last clause preceding eessaacc. + There may be an arbitrary number of case clauses. The first + pattern that matches determines the _l_i_s_t that is executed. When a match is found, ccaassee executes the corresponding _l_i_s_t. If - the ;;;; operator terminates the case clause, the ccaassee command - completes after the first match. Using ;;&& in place of ;;;; causes - execution to continue with the _l_i_s_t associated with the next - pattern list. Using ;;;;&& in place of ;;;; causes the shell to test - the next pattern list in the statement, if any, and execute any - associated _l_i_s_t if the match succeeds, continuing the case - statement execution as if the pattern list had not matched. The - exit status is zero if no pattern matches. - - Otherwise, it is the exit status of the last command executed in - the last _l_i_s_t executed. + the ;;;; operator terminates the case clause, the ccaassee command + completes after the first match. Using the ;;&& terminator con- + tinues execution with the _l_i_s_t associated with the next clause, + if any. Using the ;;;;&& terminator causes the shell to test the + pattern list in the next clause, if any, and execute any associ- + ated _l_i_s_t if the match succeeds, continuing the case statement + execution as if the pattern list had not matched. + + The exit status is zero if no pattern matches. Otherwise, it is + the exit status of the last command executed in the last _l_i_s_t + executed. iiff _l_i_s_t; tthheenn _l_i_s_t; [ eelliiff _l_i_s_t; tthheenn _l_i_s_t; ] ... [ eellssee _l_i_s_t; ] ffii - The iiff _l_i_s_t is executed. If its exit status is zero, the tthheenn - _l_i_s_t is executed. Otherwise, each eelliiff _l_i_s_t is executed in - turn, and if its exit status is zero, the corresponding tthheenn + The iiff _l_i_s_t is executed. If its exit status is zero, the tthheenn + _l_i_s_t is executed. Otherwise, each eelliiff _l_i_s_t is executed in + turn, and if its exit status is zero, the corresponding tthheenn _l_i_s_t is executed and the command completes. Otherwise, the eellssee - _l_i_s_t is executed, if present. The exit status is the exit sta- + _l_i_s_t is executed, if present. The exit status is the exit sta- tus of the last command executed, or zero if no condition tested true. wwhhiillee _l_i_s_t_-_1; ddoo _l_i_s_t_-_2; ddoonnee uunnttiill _l_i_s_t_-_1; ddoo _l_i_s_t_-_2; ddoonnee - The wwhhiillee command continuously executes the list _l_i_s_t_-_2 as long + The wwhhiillee command continuously executes the list _l_i_s_t_-_2 as long as the last command in the list _l_i_s_t_-_1 returns an exit status of - zero. The uunnttiill command is identical to the wwhhiillee command, ex- + zero. The uunnttiill command is identical to the wwhhiillee command, ex- cept that the test is negated: _l_i_s_t_-_2 is executed as long as the last command in _l_i_s_t_-_1 returns a non-zero exit status. The exit status of the wwhhiillee and uunnttiill commands is the exit status of the @@ -553,143 +576,143 @@ SSHHEELLLL GGRRAAMMMMAARR CCoopprroocceesssseess A _c_o_p_r_o_c_e_s_s is a shell command preceded by the ccoopprroocc reserved word. A - coprocess is executed asynchronously in a subshell, as if the command - had been terminated with the && control operator, with a two-way pipe + coprocess is executed asynchronously in a subshell, as if the command + had been terminated with the && control operator, with a two-way pipe established between the executing shell and the coprocess. The syntax for a coprocess is: ccoopprroocc [_N_A_M_E] _c_o_m_m_a_n_d [_r_e_d_i_r_e_c_t_i_o_n_s] - This creates a coprocess named _N_A_M_E. _c_o_m_m_a_n_d may be either a simple - command or a compound command (see above). _N_A_M_E is a shell variable + This creates a coprocess named _N_A_M_E. _c_o_m_m_a_n_d may be either a simple + command or a compound command (see above). _N_A_M_E is a shell variable name. If _N_A_M_E is not supplied, the default name is CCOOPPRROOCC. The recommended form to use for a coprocess is ccoopprroocc _N_A_M_E { _c_o_m_m_a_n_d [_r_e_d_i_r_e_c_t_i_o_n_s]; } - This form is preferred because simple commands result in the coprocess - always being named CCOOPPRROOCC, and it is simpler to use and more complete + This form is preferred because simple commands result in the coprocess + always being named CCOOPPRROOCC, and it is simpler to use and more complete than the other compound commands. - If _c_o_m_m_a_n_d is a compound command, _N_A_M_E is optional. The word following - ccoopprroocc determines whether that word is interpreted as a variable name: - it is interpreted as _N_A_M_E if it is not a reserved word that introduces - a compound command. If _c_o_m_m_a_n_d is a simple command, _N_A_M_E is not al- - lowed; this is to avoid confusion between _N_A_M_E and the first word of + If _c_o_m_m_a_n_d is a compound command, _N_A_M_E is optional. The word following + ccoopprroocc determines whether that word is interpreted as a variable name: + it is interpreted as _N_A_M_E if it is not a reserved word that introduces + a compound command. If _c_o_m_m_a_n_d is a simple command, _N_A_M_E is not al- + lowed; this is to avoid confusion between _N_A_M_E and the first word of the simple command. - When the coprocess is executed, the shell creates an array variable - (see AArrrraayyss below) named _N_A_M_E in the context of the executing shell. - The standard output of _c_o_m_m_a_n_d is connected via a pipe to a file de- - scriptor in the executing shell, and that file descriptor is assigned + When the coprocess is executed, the shell creates an array variable + (see AArrrraayyss below) named _N_A_M_E in the context of the executing shell. + The standard output of _c_o_m_m_a_n_d is connected via a pipe to a file de- + scriptor in the executing shell, and that file descriptor is assigned to _N_A_M_E[0]. The standard input of _c_o_m_m_a_n_d is connected via a pipe to a file descriptor in the executing shell, and that file descriptor is as- - signed to _N_A_M_E[1]. This pipe is established before any redirections + signed to _N_A_M_E[1]. This pipe is established before any redirections specified by the command (see RREEDDIIRREECCTTIIOONN below). The file descriptors - can be utilized as arguments to shell commands and redirections using - standard word expansions. Other than those created to execute command - and process substitutions, the file descriptors are not available in + can be utilized as arguments to shell commands and redirections using + standard word expansions. Other than those created to execute command + and process substitutions, the file descriptors are not available in subshells. - The process ID of the shell spawned to execute the coprocess is avail- - able as the value of the variable _N_A_M_E_PID. The wwaaiitt builtin may be + The process ID of the shell spawned to execute the coprocess is avail- + able as the value of the variable _N_A_M_E_PID. The wwaaiitt builtin may be used to wait for the coprocess to terminate. - Since the coprocess is created as an asynchronous command, the ccoopprroocc - command always returns success. The return status of a coprocess is + Since the coprocess is created as an asynchronous command, the ccoopprroocc + command always returns success. The return status of a coprocess is the exit status of _c_o_m_m_a_n_d. SShheellll FFuunnccttiioonn DDeeffiinniittiioonnss - 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. + 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: _f_n_a_m_e () _c_o_m_p_o_u_n_d_-_c_o_m_m_a_n_d [_r_e_d_i_r_e_c_t_i_o_n] ffuunnccttiioonn _f_n_a_m_e [()] _c_o_m_p_o_u_n_d_-_c_o_m_m_a_n_d [_r_e_d_i_r_e_c_t_i_o_n] This defines a function named _f_n_a_m_e. The reserved word ffuunnccttiioonn - is optional. If the ffuunnccttiioonn reserved word is supplied, the - parentheses are optional. The _b_o_d_y of the function is the com- - pound command _c_o_m_p_o_u_n_d_-_c_o_m_m_a_n_d (see CCoommppoouunndd CCoommmmaannddss above). - That command is usually a _l_i_s_t of commands between { and }, but + is optional. If the ffuunnccttiioonn reserved word is supplied, the + parentheses are optional. The _b_o_d_y of the function is the com- + pound command _c_o_m_p_o_u_n_d_-_c_o_m_m_a_n_d (see CCoommppoouunndd CCoommmmaannddss above). + That command is usually a _l_i_s_t of commands between { and }, but may be any command listed under CCoommppoouunndd CCoommmmaannddss above. If the ffuunnccttiioonn reserved word is used, but the parentheses are not sup- plied, the braces are recommended. _c_o_m_p_o_u_n_d_-_c_o_m_m_a_n_d is executed - whenever _f_n_a_m_e is specified as the name of a simple command. + whenever _f_n_a_m_e is specified as the name of a simple command. When in posix mode, _f_n_a_m_e must be a valid shell _n_a_m_e and may not - be the name of one of the POSIX _s_p_e_c_i_a_l _b_u_i_l_t_i_n_s. In default - mode, a function name can be any unquoted shell word that does + be the name of one of the POSIX _s_p_e_c_i_a_l _b_u_i_l_t_i_n_s. In default + mode, a function name can be any unquoted shell word that does not contain $$. - Any redirections (see RREEDDIIRREECCTTIIOONN below) specified when a function is + Any redirections (see RREEDDIIRREECCTTIIOONN 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 + 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 FFUUNNCCTTIIOONNSS below.) CCOOMMMMEENNTTSS In a non-interactive shell, or an interactive shell in which the iinntteerr-- - aaccttiivvee__ccoommmmeennttss option to the sshhoopptt builtin is enabled (see SSHHEELLLL - BBUUIILLTTIINN CCOOMMMMAANNDDSS below), a word beginning with ## introduces a comment. + aaccttiivvee__ccoommmmeennttss option to the sshhoopptt builtin is enabled (see SSHHEELLLL + BBUUIILLTTIINN CCOOMMMMAANNDDSS below), a word beginning with ## introduces a comment. A word begins at the beginning of a line, after unquoted whitespace, or - after an operator. The comment causes that word and all remaining - characters on that line to be ignored. An interactive shell without - the iinntteerraaccttiivvee__ccoommmmeennttss option enabled does not allow comments. The + after an operator. The comment causes that word and all remaining + characters on that line to be ignored. An interactive shell without + the iinntteerraaccttiivvee__ccoommmmeennttss option enabled does not allow comments. The iinntteerraaccttiivvee__ccoommmmeennttss option is enabled by default in interactive shells. QQUUOOTTIINNGG - _Q_u_o_t_i_n_g is used to remove the special meaning of certain characters or - words to the shell. Quoting can be used to disable special treatment + _Q_u_o_t_i_n_g 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 _m_e_t_a_c_h_a_r_a_c_t_e_r_s listed above under DDEEFFIINNIITTIIOONNSS has special + Each of the _m_e_t_a_c_h_a_r_a_c_t_e_r_s listed above under DDEEFFIINNIITTIIOONNSS has special meaning to the shell and must be quoted if it is to represent itself. - When the command history expansion facilities are being used (see HHIISS-- + When the command history expansion facilities are being used (see HHIISS-- TTOORRYY EEXXPPAANNSSIIOONN below), the _h_i_s_t_o_r_y _e_x_p_a_n_s_i_o_n character, usually !!, must be quoted to prevent history expansion. There are four quoting mechanisms: the _e_s_c_a_p_e _c_h_a_r_a_c_t_e_r, single quotes, double quotes, and dollar-single quotes. - A non-quoted backslash (\\) is the _e_s_c_a_p_e _c_h_a_r_a_c_t_e_r. It preserves the - literal value of the next character that follows, removing any special - meaning it has, with the exception of . If a \\ pair - appears, and the backslash is not itself quoted, the \\ is - treated as a line continuation (that is, it is removed from the input + A non-quoted backslash (\\) is the _e_s_c_a_p_e _c_h_a_r_a_c_t_e_r. It preserves the + literal value of the next character that follows, removing any special + meaning it has, with the exception of . If a \\ pair + appears, and the backslash is not itself quoted, the \\ is + treated as a line continuation (that is, it is removed from the input stream and effectively ignored). - Enclosing characters in single quotes preserves the literal value of + 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. - Enclosing characters in double quotes preserves the literal value of - all characters within the quotes, with the exception of $$, ``, \\, and, + Enclosing characters in double quotes preserves the literal value of + all characters within the quotes, with the exception of $$, ``, \\, and, when history expansion is enabled, !!. When the shell is in posix mode, - the !! has no special meaning within double quotes, even when history - expansion is enabled. The characters $$ and `` retain their special - meaning within double quotes. The backslash retains its special mean- - ing only when followed by one of the following characters: $$, ``, "", \\, + the !! has no special meaning within double quotes, even when history + expansion is enabled. The characters $$ and `` retain their special + meaning within double quotes. The backslash retains its special mean- + ing only when followed by one of the following characters: $$, ``, "", \\, or <>. Backslashes preceding characters without a special mean- ing are left unmodified. - A double quote may be quoted within double quotes by preceding it with + A double quote may be quoted within double quotes by preceding it with a backslash. If enabled, history expansion will be performed unless an - !! appearing in double quotes is escaped using a backslash. The back- + !! appearing in double quotes is escaped using a backslash. The back- slash preceding the !! is not removed. - The special parameters ** and @@ have special meaning when in double + The special parameters ** and @@ have special meaning when in double quotes (see PPAARRAAMMEETTEERRSS below). - Character sequences of the form $$'_s_t_r_i_n_g' are treated as a special - variant of single quotes. The sequence expands to _s_t_r_i_n_g, with back- - slash-escaped characters in _s_t_r_i_n_g replaced as specified by the ANSI C - standard. Backslash escape sequences, if present, are decoded as fol- + Character sequences of the form $$'_s_t_r_i_n_g' are treated as a special + variant of single quotes. The sequence expands to _s_t_r_i_n_g, with back- + slash-escaped characters in _s_t_r_i_n_g replaced as specified by the ANSI C + standard. Backslash escape sequences, if present, are decoded as fol- lows: \\aa alert (bell) \\bb backspace @@ -704,88 +727,88 @@ QQUUOOTTIINNGG \\'' single quote \\"" double quote \\?? question mark - \\_n_n_n The eight-bit character whose value is the octal value + \\_n_n_n The eight-bit character whose value is the octal value _n_n_n (one to three octal digits). - \\xx_H_H The eight-bit character whose value is the hexadecimal + \\xx_H_H The eight-bit character whose value is the hexadecimal value _H_H (one or two hex digits). - \\uu_H_H_H_H The Unicode (ISO/IEC 10646) character whose value is the + \\uu_H_H_H_H The Unicode (ISO/IEC 10646) character whose value is the hexadecimal value _H_H_H_H (one to four hex digits). \\UU_H_H_H_H_H_H_H_H - The Unicode (ISO/IEC 10646) character whose value is the + The Unicode (ISO/IEC 10646) character whose value is the hexadecimal value _H_H_H_H_H_H_H_H (one to eight hex digits). \\cc_x A control-_x character. - The expanded result is single-quoted, as if the dollar sign had not + The expanded result is single-quoted, as if the dollar sign had not been present. TTrraannssllaattiinngg SSttrriinnggss A double-quoted string preceded by a dollar sign ($$"_s_t_r_i_n_g") causes the - string to be translated according to the current locale. The _g_e_t_t_e_x_t - infrastructure performs the lookup and translation, using the LLCC__MMEESS-- - SSAAGGEESS, TTEEXXTTDDOOMMAAIINNDDIIRR, and TTEEXXTTDDOOMMAAIINN shell variables. If the current + string to be translated according to the current locale. The _g_e_t_t_e_x_t + infrastructure performs the lookup and translation, using the LLCC__MMEESS-- + SSAAGGEESS, TTEEXXTTDDOOMMAAIINNDDIIRR, and TTEEXXTTDDOOMMAAIINN shell variables. If the current locale is CC or PPOOSSIIXX, if there are no translations available, or if the string is not translated, the dollar sign is ignored, and the string is - treated as double-quoted as described above. This is a form of double + treated as double-quoted as described above. This is a form of double quoting, so the string remains double-quoted by default, whether or not - it is translated and replaced. If the nnooeexxppaanndd__ttrraannssllaattiioonn option is - enabled using the sshhoopptt builtin, translated strings are single-quoted - instead of double-quoted. See the description of sshhoopptt below under + it is translated and replaced. If the nnooeexxppaanndd__ttrraannssllaattiioonn option is + enabled using the sshhoopptt builtin, translated strings are single-quoted + instead of double-quoted. See the description of sshhoopptt below under SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS. PPAARRAAMMEETTEERRSS - A _p_a_r_a_m_e_t_e_r is an entity that stores values. It can be a _n_a_m_e, a num- - ber, or one of the special characters listed below under SSppeecciiaall PPaarraa-- + A _p_a_r_a_m_e_t_e_r is an entity that stores values. It can be a _n_a_m_e, a num- + ber, or one of the special characters listed below under SSppeecciiaall PPaarraa-- mmeetteerrss. A _v_a_r_i_a_b_l_e is a parameter denoted by a _n_a_m_e. A variable has a - _v_a_l_u_e and zero or more _a_t_t_r_i_b_u_t_e_s. Attributes are assigned using the - ddeeccllaarree builtin command (see ddeeccllaarree below in SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS). + _v_a_l_u_e and zero or more _a_t_t_r_i_b_u_t_e_s. Attributes are assigned using the + ddeeccllaarree builtin command (see ddeeccllaarree below in SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS). The eexxppoorrtt and rreeaaddoonnllyy builtins assign specific attributes. 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 + a valid value. Once a variable is set, it may be unset only by using the uunnsseett builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). A _v_a_r_i_a_b_l_e is assigned to using a statement of the form _n_a_m_e=[_v_a_l_u_e] - If _v_a_l_u_e is not given, the variable is assigned the null string. All - _v_a_l_u_e_s undergo tilde expansion, parameter and variable expansion, com- - mand substitution, arithmetic expansion, and quote removal (see EEXXPPAANN-- + If _v_a_l_u_e is not given, the variable is assigned the null string. All + _v_a_l_u_e_s undergo tilde expansion, parameter and variable expansion, com- + mand substitution, arithmetic expansion, and quote removal (see EEXXPPAANN-- SSIIOONN below). If the variable has its iinntteeggeerr attribute set, then _v_a_l_u_e is evaluated as an arithmetic expression even if the $$((((...)))) expansion is not used (see AArriitthhmmeettiicc EExxppaannssiioonn below). Word splitting and path- - name expansion are not performed. Assignment statements may also ap- + name expansion are not performed. Assignment statements may also ap- pear as arguments to the aalliiaass, ddeeccllaarree, ttyyppeesseett, eexxppoorrtt, rreeaaddoonnllyy, and - llooccaall builtin commands (_d_e_c_l_a_r_a_t_i_o_n commands). When in posix mode, - these builtins may appear in a command after one or more instances of + llooccaall builtin commands (_d_e_c_l_a_r_a_t_i_o_n commands). When in posix mode, + these builtins may appear in a command after one or more instances of the ccoommmmaanndd 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, the "+=" operator appends to or adds to - the variable's previous value. This includes arguments to _d_e_c_l_a_r_a_t_i_o_n - commands such as ddeeccllaarree that accept assignment statements. When "+=" - is applied to a variable for which the iinntteeggeerr attribute has been set, + In the context where an assignment statement is assigning a value to a + shell variable or array index, the "+=" operator appends to or adds to + the variable's previous value. This includes arguments to _d_e_c_l_a_r_a_t_i_o_n + commands such as ddeeccllaarree that accept assignment statements. When "+=" + is applied to a variable for which the iinntteeggeerr attribute has been set, the variable's current value and _v_a_l_u_e are each evaluated as arithmetic - expressions, and the sum of the results is assigned as the variable's + expressions, and the sum of the results is assigned as the variable's value. The current value is usually an integer constant, but may be an - expression. When "+=" is applied to an array variable using compound + expression. When "+=" is applied to an array variable using compound assignment (see AArrrraayyss 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 ap- - plied to a string-valued variable, _v_a_l_u_e is expanded and appended to + 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 ap- + plied to a string-valued variable, _v_a_l_u_e is expanded and appended to the variable's value. A variable can be assigned the _n_a_m_e_r_e_f attribute using the --nn option to - the ddeeccllaarree or llooccaall builtin commands (see the descriptions of ddeeccllaarree - and llooccaall below) to create a _n_a_m_e_r_e_f, or a reference to another vari- - able. This allows variables to be manipulated indirectly. Whenever - the nameref variable is referenced, assigned to, unset, or has its at- - tributes modified (other than using or changing the _n_a_m_e_r_e_f attribute - itself), the operation is actually performed on the variable specified - by the nameref variable's value. A nameref is commonly used within + the ddeeccllaarree or llooccaall builtin commands (see the descriptions of ddeeccllaarree + and llooccaall below) to create a _n_a_m_e_r_e_f, or a reference to another vari- + able. This allows variables to be manipulated indirectly. Whenever + the nameref variable is referenced, assigned to, unset, or has its at- + tributes modified (other than using or changing the _n_a_m_e_r_e_f attribute + itself), the operation is actually performed on the variable specified + by the nameref variable's value. A nameref is commonly used within shell functions to refer to a variable whose name is passed as an argu- - ment to the function. For instance, if a variable name is passed to a + ment to the function. For instance, if a variable name is passed to a shell function as its first argument, running declare -n ref=$1 @@ -794,211 +817,211 @@ PPAARRAAMMEETTEERRSS the variable name passed as the first argument. References and assign- ments to rreeff, and changes to its attributes, are treated as references, assignments, and attribute modifications to the variable whose name was - passed as $$11. If the control variable in a ffoorr loop has the nameref - attribute, the list of words can be a list of shell variables, and a - name reference is established for each word in the list, in turn, when - the loop is executed. Array variables cannot be given the nnaammeerreeff at- - tribute. However, nameref variables can reference array variables and + passed as $$11. If the control variable in a ffoorr loop has the nameref + attribute, the list of words can be a list of shell variables, and a + name reference is established for each word in the list, in turn, when + the loop is executed. Array variables cannot be given the nnaammeerreeff at- + tribute. However, nameref variables can reference array variables and subscripted array variables. Namerefs can be unset using the --nn option to the uunnsseett builtin. Otherwise, if uunnsseett is executed with the name of - a nameref variable as an argument, the variable referenced by the + a nameref variable as an argument, the variable referenced by the nameref variable is unset. - When the shell starts, it reads its environment and creates a shell - variable from each environment variable that has a valid name, as de- + When the shell starts, it reads its environment and creates a shell + variable from each environment variable that has a valid name, as de- scribed below (see EENNVVIIRROONNMMEENNTT). PPoossiittiioonnaall PPaarraammeetteerrss - A _p_o_s_i_t_i_o_n_a_l _p_a_r_a_m_e_t_e_r is a parameter denoted by one or more digits, + A _p_o_s_i_t_i_o_n_a_l _p_a_r_a_m_e_t_e_r 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 sseett builtin command. Positional parameters may not be assigned to - with assignment statements. The positional parameters are temporarily + the shell's arguments when it is invoked, and may be reassigned using + the sseett 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 FFUUNNCCTTIIOONNSS below). - When a positional parameter consisting of more than a single digit is + When a positional parameter consisting of more than a single digit is expanded, it must be enclosed in braces (see EEXXPPAANNSSIIOONN below). Without braces, a digit following $ can only refer to one of the first nine po- - sitional parameters ($$11--$$99) or the special parameter $$00 (see the next + sitional parameters ($$11--$$99) or the special parameter $$00 (see the next section). SSppeecciiaall PPaarraammeetteerrss - The shell treats several parameters specially. These parameters may + The shell treats several parameters specially. These parameters may only be referenced; assignment to them is not allowed. Special parame- ters are denoted by one of the following characters. - ** ($$**) Expands to the positional parameters, starting from one. - When the expansion is not within double quotes, each positional - parameter expands to a separate word. In contexts where word - expansions are performed, those words are subject to further - word splitting and pathname expansion. When the expansion oc- - curs within double quotes, it expands to a single word with the - value of each parameter separated by the first character of the + ** ($$**) Expands to the positional parameters, starting from one. + When the expansion is not within double quotes, each positional + parameter expands to a separate word. In contexts where word + expansions are performed, those words are subject to further + word splitting and pathname expansion. When the expansion oc- + curs within double quotes, it expands to a single word with the + value of each parameter separated by the first character of the IIFFSS variable. That is, ""$$**"" is equivalent to ""$$11_c$$22_c......"", where - _c is the first character of the value of the IIFFSS variable. If + _c is the first character of the value of the IIFFSS variable. If IIFFSS is unset, the parameters are separated by spaces. If IIFFSS is null, the parameters are joined without intervening separators. - @@ ($$@@) Expands to the positional parameters, starting from one. + @@ ($$@@) Expands to the positional parameters, starting from one. In contexts where word splitting is performed, this expands each - positional parameter to a separate word; if not within double - quotes, these words are subject to word splitting. In contexts + positional parameter to a separate word; if not within double + quotes, these words are subject to word splitting. In contexts where word splitting is not performed, such as the value portion - of an assignment statement, this expands to a single word with + of an assignment statement, this expands to a single word with each positional parameter separated by a space. When the expan- - sion occurs within double quotes, and word splitting is per- - formed, each parameter expands to a separate word. That is, + sion occurs within double quotes, and word splitting is per- + formed, each parameter expands to a separate word. That is, ""$$@@"" is equivalent to ""$$11"" ""$$22"" ...... If the double-quoted expan- - sion occurs within a word, the expansion of the first parameter + sion occurs within a word, the expansion of the first parameter is joined with the expansion of the beginning part of the origi- nal word, and the expansion of the last parameter is joined with the expansion of the last part of the original word. When there - are no positional parameters, ""$$@@"" and $$@@ expand to nothing + are no positional parameters, ""$$@@"" and $$@@ expand to nothing (i.e., they are removed). ## ($$##) Expands to the number of positional parameters in decimal. - ?? ($$??) Expands to the exit status of the most recently executed + ?? ($$??) Expands to the exit status of the most recently executed command. -- ($$--) Expands to the current option flags as specified upon invo- - cation, by the sseett builtin command, or those set by the shell + cation, by the sseett builtin command, or those set by the shell itself (such as the --ii option). - $$ ($$$$) Expands to the process ID of the shell. In a subshell, it + $$ ($$$$) Expands to the process ID of the shell. In a subshell, it expands to the process ID of the parent shell, not the subshell. - !! ($$!!)Expands to the process ID of the job most recently placed + !! ($$!!)Expands to the process ID of the job most recently placed into the background, whether executed as an asynchronous command or using the bbgg builtin (see JJOOBB CCOONNTTRROOLL below). - 00 ($$00) Expands to the name of the shell or shell script. This is - set at shell initialization. If bbaasshh is invoked with a file of - commands, $$00 is set to the name of that file. If bbaasshh is + 00 ($$00) Expands to the name of the shell or shell script. This is + set at shell initialization. If bbaasshh is invoked with a file of + commands, $$00 is set to the name of that file. If bbaasshh is started with the --cc option, then $$00 is set to the first argument - after the string to be executed, if one is present. Otherwise, + after the string to be executed, if one is present. Otherwise, it is set to the filename used to invoke bbaasshh, as given by argu- ment zero. SShheellll VVaarriiaabblleess The shell sets following variables: - __ ($$__, an underscore) This has a number of meanings depending on + __ ($$__, an underscore) This has a number of meanings depending on context. At shell startup, __ is set to the pathname used to in- - voke the shell or shell script being executed as passed in the - environment or argument list. Subsequently, it expands to the - last argument to the previous simple command executed in the - foreground, after expansion. It is also set to the full path- - name used to invoke each command executed and placed in the en- - vironment exported to that command. When checking mail, $$__ ex- + voke the shell or shell script being executed as passed in the + environment or argument list. Subsequently, it expands to the + last argument to the previous simple command executed in the + foreground, after expansion. It is also set to the full path- + name used to invoke each command executed and placed in the en- + vironment exported to that command. When checking mail, $$__ ex- pands to the name of the mail file currently being checked. - BBAASSHH Expands to the full filename used to invoke this instance of + BBAASSHH Expands to the full filename used to invoke this instance of bbaasshh. BBAASSHHOOPPTTSS - A colon-separated list of enabled shell options. Each word in - the list is a valid argument for the --ss option to the sshhoopptt + A colon-separated list of enabled shell options. Each word in + the list is a valid argument for the --ss option to the sshhoopptt builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). The options - appearing in BBAASSHHOOPPTTSS are those reported as _o_n by sshhoopptt. If - this variable is in the environment when bbaasshh starts up, the + appearing in BBAASSHHOOPPTTSS are those reported as _o_n by sshhoopptt. If + this variable is in the environment when bbaasshh starts up, the shell enables each option in the list before reading any startup - files. If this variable is exported, child shells will enable + files. If this variable is exported, child shells will enable each option in the list. This variable is read-only. BBAASSHHPPIIDD - Expands to the process ID of the current bbaasshh process. This - differs from $$$$ under certain circumstances, such as subshells - that do not require bbaasshh to be re-initialized. Assignments to - BBAASSHHPPIIDD have no effect. If BBAASSHHPPIIDD is unset, it loses its spe- + Expands to the process ID of the current bbaasshh process. This + differs from $$$$ under certain circumstances, such as subshells + that do not require bbaasshh to be re-initialized. Assignments to + BBAASSHHPPIIDD have no effect. If BBAASSHHPPIIDD is unset, it loses its spe- cial properties, even if it is subsequently reset. BBAASSHH__AALLIIAASSEESS - An associative array variable whose members correspond to the - internal list of aliases as maintained by the aalliiaass builtin. - Elements added to this array appear in the alias list; however, - unsetting array elements currently does not remove aliases from - the alias list. If BBAASSHH__AALLIIAASSEESS is unset, it loses its special + An associative array variable whose members correspond to the + internal list of aliases as maintained by the aalliiaass builtin. + Elements added to this array appear in the alias list; however, + unsetting array elements currently does not remove aliases from + the alias list. If BBAASSHH__AALLIIAASSEESS is unset, it loses its special properties, even if it is subsequently reset. BBAASSHH__AARRGGCC - An array variable whose values are the number of parameters in + An array variable whose values are the number of parameters in each frame of the current bbaasshh execution call stack. The number - of parameters to the current subroutine (shell function or - script executed with .. or ssoouurrccee) is at the top of the stack. - When a subroutine is executed, the number of parameters passed + of parameters to the current subroutine (shell function or + script executed with .. or ssoouurrccee) is at the top of the stack. + When a subroutine is executed, the number of parameters passed is pushed onto BBAASSHH__AARRGGCC. The shell sets BBAASSHH__AARRGGCC only when in extended debugging mode (see the description of the eexxttddeebbuugg op- - tion to the sshhoopptt builtin below). Setting eexxttddeebbuugg after the + tion to the sshhoopptt builtin below). Setting eexxttddeebbuugg after the shell has started to execute a script, or referencing this vari- - able when eexxttddeebbuugg is not set, may result in inconsistent val- + able when eexxttddeebbuugg is not set, may result in inconsistent val- ues. Assignments to BBAASSHH__AARRGGCC have no effect, and it may not be unset. BBAASSHH__AARRGGVV - An array variable containing all of the parameters in the cur- + An array variable containing all of the parameters in the cur- rent bbaasshh execution call stack. The final parameter of the last - subroutine call is at the top of the stack; the first parameter + subroutine call is at the top of the stack; the first parameter of the initial call is at the bottom. When a subroutine is exe- - cuted, the shell pushes the supplied parameters onto BBAASSHH__AARRGGVV. - The shell sets BBAASSHH__AARRGGVV only when in extended debugging mode + cuted, the shell pushes the supplied parameters onto BBAASSHH__AARRGGVV. + The shell sets BBAASSHH__AARRGGVV only when in extended debugging mode (see the description of the eexxttddeebbuugg option to the sshhoopptt builtin below). Setting eexxttddeebbuugg after the shell has started to execute a script, or referencing this variable when eexxttddeebbuugg is not set, - may result in inconsistent values. Assignments to BBAASSHH__AARRGGVV + may result in inconsistent values. Assignments to BBAASSHH__AARRGGVV have no effect, and it may not be unset. BBAASSHH__AARRGGVV00 - When referenced, this variable expands to the name of the shell + When referenced, this variable expands to the name of the shell or shell script (identical to $$00; see the description of special - parameter 0 above). Assigning a value to BBAASSHH__AARRGGVV00 sets $$00 to - the same value. If BBAASSHH__AARRGGVV00 is unset, it loses its special + parameter 0 above). Assigning a value to BBAASSHH__AARRGGVV00 sets $$00 to + the same value. If BBAASSHH__AARRGGVV00 is unset, it loses its special properties, even if it is subsequently reset. BBAASSHH__CCMMDDSS - An associative array variable whose members correspond to the - internal hash table of commands as maintained by the hhaasshh + An associative array variable whose members correspond to the + internal hash table of commands as maintained by the hhaasshh builtin. Adding elements to this array makes them appear in the hash table; however, unsetting array elements currently does not - remove command names from the hash table. If BBAASSHH__CCMMDDSS is un- + remove command names from the hash table. If BBAASSHH__CCMMDDSS is un- set, it loses its special properties, even if it is subsequently reset. BBAASSHH__CCOOMMMMAANNDD - Expands to the command currently being executed or about to be - executed, unless the shell is executing a command as the result + Expands to 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. If BBAASSHH__CCOOMMMMAANNDD is unset, it loses its special + of the trap. If BBAASSHH__CCOOMMMMAANNDD is unset, it loses its special properties, even if it is subsequently reset. BBAASSHH__EEXXEECCUUTTIIOONN__SSTTRRIINNGG The command argument to the --cc invocation option. BBAASSHH__LLIINNEENNOO - An array variable whose members are the line numbers in source - files where each corresponding member of FFUUNNCCNNAAMMEE was invoked. + An array variable whose members are the line numbers in source + files where each corresponding member of FFUUNNCCNNAAMMEE was invoked. $${{BBAASSHH__LLIINNEENNOO[[_$_i]]}} is the line number in the source file ($${{BBAASSHH__SSOOUURRCCEE[[_$_i_+_1]]}}) where $${{FFUUNNCCNNAAMMEE[[_$_i]]}} was called (or - $${{BBAASSHH__LLIINNEENNOO[[_$_i_-_1]]}} if referenced within another shell func- - tion). Use LLIINNEENNOO to obtain the current line number. Assign- + $${{BBAASSHH__LLIINNEENNOO[[_$_i_-_1]]}} if referenced within another shell func- + tion). Use LLIINNEENNOO to obtain the current line number. Assign- ments to BBAASSHH__LLIINNEENNOO have no effect, and it may not be unset. BBAASSHH__LLOOAADDAABBLLEESS__PPAATTHH - A colon-separated list of directories in which the eennaabbllee com- + A colon-separated list of directories in which the eennaabbllee com- mand looks for dynamically loadable builtins. BBAASSHH__MMOONNOOSSEECCOONNDDSS - Each time this variable is referenced, it expands to the value - returned by the system's monotonic clock, if one is available. - If there is no monotonic clock, this is equivalent to EEPPOOCCHHSSEECC-- - OONNDDSS. If BBAASSHH__MMOONNOOSSEECCOONNDDSS is unset, it loses its special prop- + Each time this variable is referenced, it expands to the value + returned by the system's monotonic clock, if one is available. + If there is no monotonic clock, this is equivalent to EEPPOOCCHHSSEECC-- + OONNDDSS. If BBAASSHH__MMOONNOOSSEECCOONNDDSS is unset, it loses its special prop- erties, even if it is subsequently reset. BBAASSHH__RREEMMAATTCCHH - An array variable whose members are assigned by the ==~~ binary - operator to the [[[[ conditional command. The element with index - 0 is the portion of the string matching the entire regular ex- + An array variable whose members are assigned by the ==~~ binary + operator to the [[[[ conditional command. The element with index + 0 is the portion of the string matching the entire regular ex- pression. The element with index _n is the portion of the string matching the _nth parenthesized subexpression. BBAASSHH__SSOOUURRCCEE - An array variable whose members are the source filenames where - the corresponding shell function names in the FFUUNNCCNNAAMMEE array + An array variable whose members are the source filenames where + the corresponding shell function names in the FFUUNNCCNNAAMMEE array variable are defined. The shell function $${{FFUUNNCCNNAAMMEE[[_$_i]]}} is de- - fined in the file $${{BBAASSHH__SSOOUURRCCEE[[_$_i]]}} and called from - $${{BBAASSHH__SSOOUURRCCEE[[_$_i_+_1]]}}. Assignments to BBAASSHH__SSOOUURRCCEE have no ef- + fined in the file $${{BBAASSHH__SSOOUURRCCEE[[_$_i]]}} and called from + $${{BBAASSHH__SSOOUURRCCEE[[_$_i_+_1]]}}. Assignments to BBAASSHH__SSOOUURRCCEE have no ef- fect, and it may not be unset. BBAASSHH__SSUUBBSSHHEELLLL - Incremented by one within each subshell or subshell environment - when the shell begins executing in that environment. The ini- - tial value is 0. If BBAASSHH__SSUUBBSSHHEELLLL is unset, it loses its spe- + Incremented by one within each subshell or subshell environment + when the shell begins executing in that environment. The ini- + tial value is 0. If BBAASSHH__SSUUBBSSHHEELLLL is unset, it loses its spe- cial properties, even if it is subsequently reset. BBAASSHH__TTRRAAPPSSIIGG - Set to the signal number corresponding to the trap action being - executed during its execution. See the description of ttrraapp un- - der SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below for information about signal + Set to the signal number corresponding to the trap action being + executed during its execution. See the description of ttrraapp un- + der SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below for information about signal numbers and trap execution. BBAASSHH__VVEERRSSIINNFFOO A readonly array variable whose members hold version information - for this instance of bbaasshh. The values assigned to the array + for this instance of bbaasshh. The values assigned to the array members are as follows: BBAASSHH__VVEERRSSIINNFFOO[[0]] The major version number (the _r_e_l_e_a_s_e). BBAASSHH__VVEERRSSIINNFFOO[[1]] The minor version number (the _v_e_r_s_i_o_n). @@ -1007,149 +1030,149 @@ PPAARRAAMMEETTEERRSS BBAASSHH__VVEERRSSIINNFFOO[[4]] The release status (e.g., _b_e_t_a). BBAASSHH__VVEERRSSIINNFFOO[[5]] The value of MMAACCHHTTYYPPEE. BBAASSHH__VVEERRSSIIOONN - Expands to a string describing the version of this instance of + Expands to a string describing the version of this instance of bbaasshh (e.g., 5.2.37(3)-release). CCOOMMPP__CCWWOORRDD - An index into $${{CCOOMMPP__WWOORRDDSS}} of the word containing the current + An index into $${{CCOOMMPP__WWOORRDDSS}} of the word containing the current cursor position. This variable is available only in shell func- - tions invoked by the programmable completion facilities (see + tions invoked by the programmable completion facilities (see PPrrooggrraammmmaabbllee CCoommpplleettiioonn below). CCOOMMPP__KKEEYY The key (or final key of a key sequence) used to invoke the cur- - rent completion function. This variable is available only in - shell functions and external commands invoked by the programma- + rent completion function. This variable is available only in + shell functions and external commands invoked by the programma- ble completion facilities (see PPrrooggrraammmmaabbllee CCoommpplleettiioonn below). CCOOMMPP__LLIINNEE - The current command line. This variable is available only in - shell functions and external commands invoked by the programma- + The current command line. This variable is available only in + shell functions and external commands invoked by the programma- ble completion facilities (see PPrrooggrraammmmaabbllee CCoommpplleettiioonn below). CCOOMMPP__PPOOIINNTT - The index of the current cursor position relative to the begin- - ning of the current command. If the current cursor position is + The index of the current cursor position relative to the begin- + ning 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 $${{##CCOOMMPP__LLIINNEE}}. This variable is available only in - shell functions and external commands invoked by the programma- + equal to $${{##CCOOMMPP__LLIINNEE}}. This variable is available only in + shell functions and external commands invoked by the programma- ble completion facilities (see PPrrooggrraammmmaabbllee CCoommpplleettiioonn below). CCOOMMPP__TTYYPPEE - Set to an integer value corresponding to the type of attempted - completion that caused a completion function to be called: _T_A_B, - for normal completion, _?, for listing completions after succes- - sive tabs, _!, for listing alternatives on partial word comple- - tion, _@, to list completions if the word is not unmodified, or - _%, for menu completion. This variable is available only in - shell functions and external commands invoked by the programma- + Set to an integer value corresponding to the type of attempted + completion that caused a completion function to be called: _T_A_B, + for normal completion, _?, for listing completions after succes- + sive tabs, _!, for listing alternatives on partial word comple- + tion, _@, to list completions if the word is not unmodified, or + _%, for menu completion. This variable is available only in + shell functions and external commands invoked by the programma- ble completion facilities (see PPrrooggrraammmmaabbllee CCoommpplleettiioonn below). CCOOMMPP__WWOORRDDBBRREEAAKKSS - The set of characters that the rreeaaddlliinnee library treats as word - separators when performing word completion. If CCOOMMPP__WWOORRDDBBRREEAAKKSS - is unset, it loses its special properties, even if it is subse- + The set of characters that the rreeaaddlliinnee library treats as word + separators when performing word completion. If CCOOMMPP__WWOORRDDBBRREEAAKKSS + is unset, it loses its special properties, even if it is subse- quently reset. CCOOMMPP__WWOORRDDSS - An array variable (see AArrrraayyss below) consisting of the individ- - ual words in the current command line. The line is split into - words as rreeaaddlliinnee would split it, using CCOOMMPP__WWOORRDDBBRREEAAKKSS as de- - scribed above. This variable is available only in shell func- - tions invoked by the programmable completion facilities (see + An array variable (see AArrrraayyss below) consisting of the individ- + ual words in the current command line. The line is split into + words as rreeaaddlliinnee would split it, using CCOOMMPP__WWOORRDDBBRREEAAKKSS as de- + scribed above. This variable is available only in shell func- + tions invoked by the programmable completion facilities (see PPrrooggrraammmmaabbllee CCoommpplleettiioonn below). - CCOOPPRROOCC An array variable (see AArrrraayyss below) created to hold the file - descriptors for output from and input to an unnamed coprocess + CCOOPPRROOCC An array variable (see AArrrraayyss below) created to hold the file + descriptors for output from and input to an unnamed coprocess (see CCoopprroocceesssseess above). DDIIRRSSTTAACCKK An array variable (see AArrrraayyss below) containing the current con- - tents of the directory stack. Directories appear in the stack - in the order they are displayed by the ddiirrss builtin. Assigning + tents of the directory stack. Directories appear in the stack + in the order they are displayed by the ddiirrss builtin. Assigning to members of this array variable may be used to modify directo- - ries already in the stack, but the ppuusshhdd and ppooppdd builtins must - be used to add and remove directories. Assigning to this vari- - able does not change the current directory. If DDIIRRSSTTAACCKK is un- + ries already in the stack, but the ppuusshhdd and ppooppdd builtins must + be used to add and remove directories. Assigning to this vari- + able does not change the current directory. If DDIIRRSSTTAACCKK is un- set, it loses its special properties, even if it is subsequently reset. EEPPOOCCHHRREEAALLTTIIMMEE Each time this parameter is referenced, it expands to the number - of seconds since the Unix Epoch (see _t_i_m_e(3)) as a floating- + of seconds since the Unix Epoch (see _t_i_m_e(3)) as a floating- point value with micro-second granularity. Assignments to - EEPPOOCCHHRREEAALLTTIIMMEE are ignored. If EEPPOOCCHHRREEAALLTTIIMMEE is unset, it loses + EEPPOOCCHHRREEAALLTTIIMMEE are ignored. If EEPPOOCCHHRREEAALLTTIIMMEE is unset, it loses its special properties, even if it is subsequently reset. EEPPOOCCHHSSEECCOONNDDSS Each time this parameter is referenced, it expands to the number - of seconds since the Unix Epoch (see _t_i_m_e(3)). Assignments to - EEPPOOCCHHSSEECCOONNDDSS are ignored. If EEPPOOCCHHSSEECCOONNDDSS is unset, it loses + of seconds since the Unix Epoch (see _t_i_m_e(3)). Assignments to + EEPPOOCCHHSSEECCOONNDDSS are ignored. If EEPPOOCCHHSSEECCOONNDDSS is unset, it loses its special properties, even if it is subsequently reset. - EEUUIIDD Expands to the effective user ID of the current user, initial- + EEUUIIDD Expands to the effective user ID of the current user, initial- ized at shell startup. This variable is readonly. FFUUNNCCNNAAMMEE - An array variable containing the names of all shell functions + 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 bot- - tom-most element (the one with the highest index) is "main". - This variable exists only when a shell function is executing. - Assignments to FFUUNNCCNNAAMMEE have no effect. If FFUUNNCCNNAAMMEE is unset, - it loses its special properties, even if it is subsequently re- + tom-most element (the one with the highest index) is "main". + This variable exists only when a shell function is executing. + Assignments to FFUUNNCCNNAAMMEE have no effect. If FFUUNNCCNNAAMMEE is unset, + it loses its special properties, even if it is subsequently re- set. - This variable can be used with BBAASSHH__LLIINNEENNOO and BBAASSHH__SSOOUURRCCEE. - Each element of FFUUNNCCNNAAMMEE has corresponding elements in + This variable can be used with BBAASSHH__LLIINNEENNOO and BBAASSHH__SSOOUURRCCEE. + Each element of FFUUNNCCNNAAMMEE has corresponding elements in BBAASSHH__LLIINNEENNOO and BBAASSHH__SSOOUURRCCEE to describe the call stack. For in- - stance, $${{FFUUNNCCNNAAMMEE[[_$_i]]}} was called from the file - $${{BBAASSHH__SSOOUURRCCEE[[_$_i_+_1]]}} at line number $${{BBAASSHH__LLIINNEENNOO[[_$_i]]}}. The + stance, $${{FFUUNNCCNNAAMMEE[[_$_i]]}} was called from the file + $${{BBAASSHH__SSOOUURRCCEE[[_$_i_+_1]]}} at line number $${{BBAASSHH__LLIINNEENNOO[[_$_i]]}}. The ccaalllleerr builtin displays the current call stack using this infor- mation. - GGRROOUUPPSS An array variable containing the list of groups of which the + GGRROOUUPPSS An array variable containing the list of groups of which the current user is a member. Assignments to GGRROOUUPPSS have no effect. - If GGRROOUUPPSS is unset, it loses its special properties, even if it + If GGRROOUUPPSS is unset, it loses its special properties, even if it is subsequently reset. HHIISSTTCCMMDD The history number, or index in the history list, of the current - command. Assignments to HHIISSTTCCMMDD have no effect. If HHIISSTTCCMMDD is - unset, it loses its special properties, even if it is subse- + command. Assignments to HHIISSTTCCMMDD have no effect. If HHIISSTTCCMMDD is + unset, it loses its special properties, even if it is subse- quently reset. HHOOSSTTNNAAMMEE Automatically set to the name of the current host. HHOOSSTTTTYYPPEE - Automatically set to a string that uniquely describes the type - of machine on which bbaasshh is executing. The default is system- + Automatically set to a string that uniquely describes the type + of machine on which bbaasshh is executing. The default is system- dependent. - LLIINNEENNOO 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 + LLIINNEENNOO 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 LLIINNEENNOO is unset, it loses its special proper- ties, even if it is subsequently reset. MMAACCHHTTYYPPEE - Automatically set to a string that fully describes the system - type on which bbaasshh is executing, in the standard GNU _c_p_u_-_c_o_m_- + Automatically set to a string that fully describes the system + type on which bbaasshh is executing, in the standard GNU _c_p_u_-_c_o_m_- _p_a_n_y_-_s_y_s_t_e_m format. The default is system-dependent. MMAAPPFFIILLEE - An array variable (see AArrrraayyss below) created to hold the text + An array variable (see AArrrraayyss below) created to hold the text read by the mmaappffiillee builtin when no variable name is supplied. OOLLDDPPWWDD The previous working directory as set by the ccdd command. - OOPPTTAARRGG The value of the last option argument processed by the ggeettooppttss + OOPPTTAARRGG The value of the last option argument processed by the ggeettooppttss builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). - OOPPTTIINNDD The index of the next argument to be processed by the ggeettooppttss + OOPPTTIINNDD The index of the next argument to be processed by the ggeettooppttss builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). - OOSSTTYYPPEE Automatically set to a string that describes the operating sys- - tem on which bbaasshh is executing. The default is system-depen- + OOSSTTYYPPEE Automatically set to a string that describes the operating sys- + tem on which bbaasshh is executing. The default is system-depen- dent. PPIIPPEESSTTAATTUUSS - An array variable (see AArrrraayyss below) containing a list of exit - status values from the commands in the most-recently-executed - foreground pipeline, which may consist of only a simple command + An array variable (see AArrrraayyss below) containing a list of exit + status values from the commands in the most-recently-executed + foreground pipeline, which may consist of only a simple command (see SSHHEELLLL GGRRAAMMMMAARR above). BBaasshh sets PPIIPPEESSTTAATTUUSS after executing - multi-element pipelines, timed and negated pipelines, simple - commands, subshells created with the ( operator, the [[[[ and (((( + multi-element pipelines, timed and negated pipelines, simple + commands, subshells created with the ( operator, the [[[[ and (((( compound commands, and after error conditions that result in the shell aborting command execution. - PPPPIIDD The process ID of the shell's parent. This variable is read- + PPPPIIDD The process ID of the shell's parent. This variable is read- only. PPWWDD The current working directory as set by the ccdd command. - RRAANNDDOOMM Each time this parameter is referenced, it expands to a random - integer between 0 and 32767. Assigning a value to RRAANNDDOOMM ini- - tializes (seeds) the sequence of random numbers. Seeding the - random number generator with the same constant value produces - the same sequence of values. If RRAANNDDOOMM is unset, it loses its + RRAANNDDOOMM Each time this parameter is referenced, it expands to a random + integer between 0 and 32767. Assigning a value to RRAANNDDOOMM ini- + tializes (seeds) the sequence of random numbers. Seeding the + random number generator with the same constant value produces + the same sequence of values. If RRAANNDDOOMM is unset, it loses its special properties, even if it is subsequently reset. RREEAADDLLIINNEE__AARRGGUUMMEENNTT - Any numeric argument given to a rreeaaddlliinnee command that was de- + Any numeric argument given to a rreeaaddlliinnee command that was de- fined using "bind -x" (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below) when it was invoked. RREEAADDLLIINNEE__LLIINNEE @@ -1157,374 +1180,374 @@ PPAARRAAMMEETTEERRSS (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). RREEAADDLLIINNEE__MMAARRKK The position of the mark (saved insertion point) in the rreeaaddlliinnee - line buffer, for use with "bind -x" (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS + line buffer, for use with "bind -x" (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). The characters between the insertion point and the mark are often called the _r_e_g_i_o_n. RREEAADDLLIINNEE__PPOOIINNTT The position of the insertion point in the rreeaaddlliinnee line buffer, for use with "bind -x" (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). - RREEPPLLYY Set to the line of input read by the rreeaadd builtin command when + RREEPPLLYY Set to the line of input read by the rreeaadd builtin command when no arguments are supplied. SSEECCOONNDDSS Each time this parameter is referenced, it expands to the number - of seconds since shell invocation. If a value is assigned to - SSEECCOONNDDSS, the value returned upon subsequent references is the - number of seconds since the assignment plus the value assigned. - The number of seconds at shell invocation and the current time + of seconds since shell invocation. If a value is assigned to + SSEECCOONNDDSS, the value returned upon subsequent references is the + number of seconds since the assignment plus the value assigned. + The number of seconds at shell invocation and the current time are always determined by querying the system clock at one-second - resolution. If SSEECCOONNDDSS is unset, it loses its special proper- + resolution. If SSEECCOONNDDSS is unset, it loses its special proper- ties, even if it is subsequently reset. SSHHEELLLLOOPPTTSS - A colon-separated list of enabled shell options. Each word in - the list is a valid argument for the --oo option to the sseett + A colon-separated list of enabled shell options. Each word in + the list is a valid argument for the --oo option to the sseett builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). The options - appearing in SSHHEELLLLOOPPTTSS are those reported as _o_n by sseett --oo. If - this variable is in the environment when bbaasshh starts up, the + appearing in SSHHEELLLLOOPPTTSS are those reported as _o_n by sseett --oo. If + this variable is in the environment when bbaasshh starts up, the shell enables each option in the list before reading any startup - files. If this variable is exported, child shells will enable + files. If this variable is exported, child shells will enable each option in the list. This variable is read-only. SSHHLLVVLL Incremented by one each time an instance of bbaasshh is started. SSRRAANNDDOOMM - Each time it is referenced, this variable expands to a 32-bit + Each time it is referenced, this variable expands to a 32-bit pseudo-random number. The random number generator is not linear - on systems that support _/_d_e_v_/_u_r_a_n_d_o_m or _a_r_c_4_r_a_n_d_o_m(3), so each + on systems that support _/_d_e_v_/_u_r_a_n_d_o_m or _a_r_c_4_r_a_n_d_o_m(3), so each returned number has no relationship to the numbers preceding it. - The random number generator cannot be seeded, so assignments to + The random number generator cannot be seeded, so assignments to this variable have no effect. If SSRRAANNDDOOMM is unset, it loses its special properties, even if it is subsequently reset. UUIIDD Expands to the user ID of the current user, initialized at shell startup. This variable is readonly. - The shell uses the following variables. In some cases, bbaasshh assigns a + The shell uses the following variables. In some cases, bbaasshh assigns a default value to a variable; these cases are noted below. BBAASSHH__CCOOMMPPAATT - The value is used to set the shell's compatibility level. See - SSHHEELLLL CCOOMMPPAATTIIBBIILLIITTYY MMOODDEE below for a description of the various + The value is used to set the shell's compatibility level. See + SSHHEELLLL CCOOMMPPAATTIIBBIILLIITTYY MMOODDEE below for a description of the various compatibility levels and their effects. The value may be a dec- - imal number (e.g., 4.2) or an integer (e.g., 42) corresponding - to the desired compatibility level. If BBAASSHH__CCOOMMPPAATT is unset or - set to the empty string, the compatibility level is set to the - default for the current version. If BBAASSHH__CCOOMMPPAATT is set to a - value that is not one of the valid compatibility levels, the - shell prints an error message and sets the compatibility level - to the default for the current version. A subset of the valid - values correspond to the compatibility levels described below - under SSHHEELLLL CCOOMMPPAATTIIBBIILLIITTYY MMOODDEE. For example, 4.2 and 42 are - valid values that correspond to the ccoommppaatt4422 sshhoopptt option and - set the compatibility level to 42. The current version is also + imal number (e.g., 4.2) or an integer (e.g., 42) corresponding + to the desired compatibility level. If BBAASSHH__CCOOMMPPAATT is unset or + set to the empty string, the compatibility level is set to the + default for the current version. If BBAASSHH__CCOOMMPPAATT is set to a + value that is not one of the valid compatibility levels, the + shell prints an error message and sets the compatibility level + to the default for the current version. A subset of the valid + values correspond to the compatibility levels described below + under SSHHEELLLL CCOOMMPPAATTIIBBIILLIITTYY MMOODDEE. For example, 4.2 and 42 are + valid values that correspond to the ccoommppaatt4422 sshhoopptt option and + set the compatibility level to 42. The current version is also a valid value. BBAASSHH__EENNVV - If this parameter is set when bbaasshh is executing a shell script, - its expanded value is interpreted as a filename containing com- - mands to initialize the shell before it reads and executes com- - mands from the script. The value of BBAASSHH__EENNVV is subjected to + If this parameter is set when bbaasshh is executing a shell script, + its expanded value is interpreted as a filename containing com- + mands to initialize the shell before it reads and executes com- + mands from the script. The value of BBAASSHH__EENNVV is subjected to parameter expansion, command substitution, and arithmetic expan- - sion before being interpreted as a filename. PPAATTHH is not used + sion before being interpreted as a filename. PPAATTHH is not used to search for the resultant filename. BBAASSHH__XXTTRRAACCEEFFDD - If set to an integer corresponding to a valid file descriptor, - bbaasshh writes the trace output generated when "set -x" is enabled - to that file descriptor, instead of the standard error. The - file descriptor is closed when BBAASSHH__XXTTRRAACCEEFFDD is unset or as- + If set to an integer corresponding to a valid file descriptor, + bbaasshh writes the trace output generated when "set -x" is enabled + to that file descriptor, instead of the standard error. The + file descriptor is closed when BBAASSHH__XXTTRRAACCEEFFDD is unset or as- signed a new value. Unsetting BBAASSHH__XXTTRRAACCEEFFDD or assigning it the - empty string causes the trace output to be sent to the standard + empty string causes the trace output to be sent to the standard error. Note that setting BBAASSHH__XXTTRRAACCEEFFDD to 2 (the standard error - file descriptor) and then unsetting it will result in the stan- + file descriptor) and then unsetting it will result in the stan- dard error being closed. - CCDDPPAATTHH The search path for the ccdd command. This is a colon-separated + CCDDPPAATTHH The search path for the ccdd command. This is a colon-separated list of directories where the shell looks for directories speci- - fied as arguments to the ccdd command. A sample value is + fied as arguments to the ccdd command. A sample value is ".:~:/usr". CCHHIILLDD__MMAAXX - Set the number of exited child status values for the shell to - remember. BBaasshh will not allow this value to be decreased below - a POSIX-mandated minimum, and there is a maximum value (cur- - rently 8192) that this may not exceed. The minimum value is + Set the number of exited child status values for the shell to + remember. BBaasshh will not allow this value to be decreased below + a POSIX-mandated minimum, and there is a maximum value (cur- + rently 8192) that this may not exceed. The minimum value is system-dependent. CCOOLLUUMMNNSS - Used by the sseelleecctt compound command to determine the terminal - width when printing selection lists. Automatically set if the - cchheecckkwwiinnssiizzee option is enabled or in an interactive shell upon + Used by the sseelleecctt compound command to determine the terminal + width when printing selection lists. Automatically set if the + cchheecckkwwiinnssiizzee option is enabled or in an interactive shell upon receipt of a SSIIGGWWIINNCCHH. CCOOMMPPRREEPPLLYY An array variable from which bbaasshh reads the possible completions - generated by a shell function invoked by the programmable com- - pletion facility (see PPrrooggrraammmmaabbllee CCoommpplleettiioonn below). Each ar- + generated by a shell function invoked by the programmable com- + pletion facility (see PPrrooggrraammmmaabbllee CCoommpplleettiioonn below). Each ar- ray element contains one possible completion. - EEMMAACCSS If bbaasshh finds this variable in the environment when the shell - starts with value "t", it assumes that the shell is running in + EEMMAACCSS If bbaasshh finds this variable in the environment when the shell + starts with value "t", it assumes that the shell is running in an Emacs shell buffer and disables line editing. - EENNVV Expanded and executed similarly to BBAASSHH__EENNVV (see IINNVVOOCCAATTIIOONN + EENNVV Expanded and executed similarly to BBAASSHH__EENNVV (see IINNVVOOCCAATTIIOONN above) when an interactive shell is invoked in posix mode. EEXXEECCIIGGNNOORREE - A colon-separated list of shell patterns (see PPaatttteerrnn MMaattcchhiinngg) - defining the set of filenames to be ignored by command search - using PPAATTHH. Files whose full pathnames match one of these pat- - terns are not considered executable files for the purposes of + A colon-separated list of shell patterns (see PPaatttteerrnn MMaattcchhiinngg) + defining the set of filenames to be ignored by command search + using PPAATTHH. Files whose full pathnames match one of these pat- + terns are not considered executable files for the purposes of completion and command execution via PPAATTHH lookup. This does not affect the behavior of the [[, tteesstt, and [[[[ commands. Full path- - names in the command hash table are not subject to EEXXEECCIIGGNNOORREE. - Use this variable to ignore shared library files that have the - executable bit set, but are not executable files. The pattern + names in the command hash table are not subject to EEXXEECCIIGGNNOORREE. + Use this variable to ignore shared library files that have the + executable bit set, but are not executable files. The pattern matching honors the setting of the eexxttgglloobb shell option. FFCCEEDDIITT The default editor for the ffcc builtin command. FFIIGGNNOORREE - A colon-separated list of suffixes to ignore when performing + A colon-separated list of suffixes to ignore when performing filename completion (see RREEAADDLLIINNEE below). A filename whose suf- - fix matches one of the entries in FFIIGGNNOORREE is excluded from the + fix matches one of the entries in FFIIGGNNOORREE is excluded from the list of matched filenames. A sample value is ".o:~". FFUUNNCCNNEESSTT - If set to a numeric value greater than 0, defines a maximum - function nesting level. Function invocations that exceed this + If set to a numeric value greater than 0, defines a maximum + function nesting level. Function invocations that exceed this nesting level cause the current command to abort. GGLLOOBBIIGGNNOORREE - A colon-separated list of patterns defining the set of file - names to be ignored by pathname expansion. If a file name - matched by a pathname expansion pattern also matches one of the - patterns in GGLLOOBBIIGGNNOORREE, it is removed from the list of matches. + A colon-separated list of patterns defining the set of file + names to be ignored by pathname expansion. If a file name + matched by a pathname expansion pattern also matches one of the + patterns in GGLLOOBBIIGGNNOORREE, it is removed from the list of matches. The pattern matching honors the setting of the eexxttgglloobb shell op- tion. GGLLOOBBSSOORRTT - Controls how the results of pathname expansion are sorted. The - value of this variable specifies the sort criteria and sort or- - der for the results of pathname expansion. If this variable is - unset or set to the null string, pathname expansion uses the - historical behavior of sorting by name, in ascending lexico- + Controls how the results of pathname expansion are sorted. The + value of this variable specifies the sort criteria and sort or- + der for the results of pathname expansion. If this variable is + unset or set to the null string, pathname expansion uses the + historical behavior of sorting by name, in ascending lexico- graphic order as determined by the LLCC__CCOOLLLLAATTEE shell variable. - If set, a valid value begins with an optional _+, which is ig- + If set, a valid value begins with an optional _+, which is ig- nored, or _-, which reverses the sort order from ascending to de- - scending, followed by a sort specifier. The valid sort speci- - fiers are _n_a_m_e, _n_u_m_e_r_i_c, _s_i_z_e, _m_t_i_m_e, _a_t_i_m_e, _c_t_i_m_e, and _b_l_o_c_k_s, + scending, followed by a sort specifier. The valid sort speci- + fiers are _n_a_m_e, _n_u_m_e_r_i_c, _s_i_z_e, _m_t_i_m_e, _a_t_i_m_e, _c_t_i_m_e, and _b_l_o_c_k_s, which sort the files on name, names in numeric rather than lexi- - cographic order, file size, modification time, access time, in- - ode change time, and number of blocks, respectively. If any of - the non-name keys compare as equal (e.g., if two files are the + cographic order, file size, modification time, access time, in- + ode change time, and number of blocks, respectively. If any of + the non-name keys compare as equal (e.g., if two files are the same size), sorting uses the name as a secondary sort key. - For example, a value of _-_m_t_i_m_e sorts the results in descending + For example, a value of _-_m_t_i_m_e sorts the results in descending order by modification time (newest first). - The _n_u_m_e_r_i_c specifier treats names consisting solely of digits - as numbers and sorts them using their numeric value (so "2" + The _n_u_m_e_r_i_c specifier treats names consisting solely of digits + as numbers and sorts them using their numeric value (so "2" sorts before "10", for example). When using _n_u_m_e_r_i_c, names con- - taining non-digits sort after all the all-digit names and are + taining non-digits sort after all the all-digit names and are sorted by name using the traditional behavior. A sort specifier of _n_o_s_o_r_t disables sorting completely; bbaasshh re- - turns the results in the order they are read from the file sys- + turns the results in the order they are read from the file sys- tem, ignoring any leading _-. - If the sort specifier is missing, it defaults to _n_a_m_e, so a - value of _+ is equivalent to the null string, and a value of _- - sorts by name in descending order. Any invalid value restores + If the sort specifier is missing, it defaults to _n_a_m_e, so a + value of _+ is equivalent to the null string, and a value of _- + sorts by name in descending order. Any invalid value restores the historical sorting behavior. HHIISSTTCCOONNTTRROOLL - A colon-separated list of values controlling how commands are - saved on the history list. If the list of values includes - _i_g_n_o_r_e_s_p_a_c_e, lines which begin with a ssppaaccee character are not - saved in the history list. A value of _i_g_n_o_r_e_d_u_p_s causes lines + A colon-separated list of values controlling how commands are + saved on the history list. If the list of values includes + _i_g_n_o_r_e_s_p_a_c_e, lines which begin with a ssppaaccee character are not + saved in the history list. A value of _i_g_n_o_r_e_d_u_p_s causes lines matching the previous history entry not to be saved. A value of _i_g_n_o_r_e_b_o_t_h is shorthand for _i_g_n_o_r_e_s_p_a_c_e and _i_g_n_o_r_e_d_u_p_s. A value of _e_r_a_s_e_d_u_p_s 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 HHIISSTTCCOONNTTRROOLL is - unset, or does not include a valid value, bbaasshh saves all lines - read by the shell parser on the history list, subject to the + to be removed from the history list before that line is saved. + Any value not in the above list is ignored. If HHIISSTTCCOONNTTRROOLL is + unset, or does not include a valid value, bbaasshh saves all lines + read by the shell parser on the history list, subject to the value of HHIISSTTIIGGNNOORREE. If the first line of a multi-line compound - command was saved, the second and subsequent lines are not - tested, and are added to the history regardless of the value of - HHIISSTTCCOONNTTRROOLL. If the first line was not saved, the second and + command was saved, the second and subsequent lines are not + tested, and are added to the history regardless of the value of + HHIISSTTCCOONNTTRROOLL. If the first line was not saved, the second and subsequent lines of the command are not saved either. HHIISSTTFFIILLEE The name of the file in which command history is saved (see HHIISS-- - TTOORRYY below). BBaasshh assigns a default value of _~_/_._b_a_s_h___h_i_s_t_o_r_y. - If HHIISSTTFFIILLEE is unset or null, the shell does not save the com- + TTOORRYY below). BBaasshh assigns a default value of _~_/_._b_a_s_h___h_i_s_t_o_r_y. + If HHIISSTTFFIILLEE is unset or null, the shell does not save the com- mand history when it exits. HHIISSTTFFIILLEESSIIZZEE The maximum number of lines contained in the history file. When - this variable is assigned a value, the history file is trun- - cated, if necessary, to contain no more than the number of his- + this variable is assigned a value, the history file is trun- + cated, if necessary, to contain no more than the number of his- tory entries that total no more than that number of lines by re- - moving the oldest entries. If the history list contains multi- - line entries, the history file may contain more lines than this - maximum to avoid leaving partial history entries. The history - file is also truncated to this size after writing it when a - shell exits or by the hhiissttoorryy builtin. If the value is 0, the - history file is truncated to zero size. Non-numeric values and - numeric values less than zero inhibit truncation. The shell - sets the default value to the value of HHIISSTTSSIIZZEE after reading + moving the oldest entries. If the history list contains multi- + line entries, the history file may contain more lines than this + maximum to avoid leaving partial history entries. The history + file is also truncated to this size after writing it when a + shell exits or by the hhiissttoorryy builtin. If the value is 0, the + history file is truncated to zero size. Non-numeric values and + numeric values less than zero inhibit truncation. The shell + sets the default value to the value of HHIISSTTSSIIZZEE after reading any startup files. HHIISSTTIIGGNNOORREE - A colon-separated list of patterns used to decide which command - lines should be saved on the history list. If a command line - matches one of the patterns in the value of HHIISSTTIIGGNNOORREE, it is - not saved on the history list. Each pattern is anchored at the - beginning of the line and must match the complete line (bbaasshh - does not implicitly append a "**"). Each pattern is tested - against the line after the checks specified by HHIISSTTCCOONNTTRROOLL are + A colon-separated list of patterns used to decide which command + lines should be saved on the history list. If a command line + matches one of the patterns in the value of HHIISSTTIIGGNNOORREE, it is + not saved on the history list. Each pattern is anchored at the + beginning of the line and must match the complete line (bbaasshh + does not implicitly append a "**"). Each pattern is tested + against the line after the checks specified by HHIISSTTCCOONNTTRROOLL are applied. In addition to the normal shell pattern matching char- - acters, "&&" matches the previous history line. A backslash es- - capes the "&&"; the backslash is removed before attempting a - match. If the first line of a multi-line compound command was - saved, the second and subsequent lines are not tested, and are - added to the history regardless of the value of HHIISSTTIIGGNNOORREE. If + acters, "&&" matches the previous history line. A backslash es- + capes the "&&"; the backslash is removed before attempting a + match. If the first line of a multi-line compound command was + saved, the second and subsequent lines are not tested, and are + added to the history regardless of the value of HHIISSTTIIGGNNOORREE. If the first line was not saved, the second and subsequent lines of - the command are not saved either. The pattern matching honors + the command are not saved either. The pattern matching honors the setting of the eexxttgglloobb shell option. HHIISSTTIIGGNNOORREE subsumes some of the function of HHIISSTTCCOONNTTRROOLL. A pat- - tern of "&" is identical to "ignoredups", and a pattern of "[ - ]*" is identical to "ignorespace". Combining these two pat- - terns, separating them with a colon, provides the functionality + tern of "&" is identical to "ignoredups", and a pattern of "[ + ]*" is identical to "ignorespace". Combining these two pat- + terns, separating them with a colon, provides the functionality of "ignoreboth". HHIISSTTSSIIZZEE - The number of commands to remember in the command history (see - HHIISSTTOORRYY below). If the value is 0, commands are not saved in + The number of commands to remember in the command history (see + HHIISSTTOORRYY below). If the value is 0, commands are not saved in the history list. Numeric values less than zero result in every - command being saved on the history list (there is no limit). - The shell sets the default value to 500 after reading any + command being saved on the history list (there is no limit). + The shell sets the default value to 500 after reading any startup files. HHIISSTTTTIIMMEEFFOORRMMAATT - If this variable is set and not null, its value is used as a + If this variable is set and not null, its value is used as a format string for _s_t_r_f_t_i_m_e(3) to print the time stamp associated - with each history entry displayed by the hhiissttoorryy builtin. If - this variable is set, the shell writes time stamps to the his- - tory file so they may be preserved across shell sessions. This - uses the history comment character to distinguish timestamps + with each history entry displayed by the hhiissttoorryy builtin. If + this variable is set, the shell writes time stamps to the his- + tory file so they may be preserved across shell sessions. This + uses the history comment character to distinguish timestamps from other history lines. HHOOMMEE The home directory of the current user; the default argument for the ccdd builtin command. The value of this variable is also used when performing tilde expansion. HHOOSSTTFFIILLEE - Contains the name of a file in the same format as _/_e_t_c_/_h_o_s_t_s + Contains the name of a file in the same format as _/_e_t_c_/_h_o_s_t_s 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 at- - tempted after the value is changed, bbaasshh adds the contents of - the new file to the existing list. If HHOOSSTTFFIILLEE is set, but has - no value, or does not name a readable file, bbaasshh attempts to - read _/_e_t_c_/_h_o_s_t_s to obtain the list of possible hostname comple- + The list of possible hostname completions may be changed while + the shell is running; the next time hostname completion is at- + tempted after the value is changed, bbaasshh adds the contents of + the new file to the existing list. If HHOOSSTTFFIILLEE is set, but has + no value, or does not name a readable file, bbaasshh attempts to + read _/_e_t_c_/_h_o_s_t_s to obtain the list of possible hostname comple- tions. When HHOOSSTTFFIILLEE is unset, bbaasshh clears the hostname list. IIFFSS The _I_n_t_e_r_n_a_l _F_i_e_l_d _S_e_p_a_r_a_t_o_r that is used for word splitting af- - ter expansion and to split lines into words with the rreeaadd + ter expansion and to split lines into words with the rreeaadd builtin command. Word splitting is described below under EEXXPPAANN-- SSIIOONN. The default value is "". IIGGNNOORREEEEOOFF Controls the action of an interactive shell on receipt of an EEOOFF character as the sole input. If set, the value is the number of - consecutive EEOOFF characters which must be typed as the first - characters on an input line before bbaasshh exits. If the variable - is set but does not have a numeric value, or the value is null, - the default value is 10. If it is unset, EEOOFF signifies the end + consecutive EEOOFF characters which must be typed as the first + characters on an input line before bbaasshh exits. If the variable + is set but does not have a numeric value, or the value is null, + the default value is 10. If it is unset, EEOOFF signifies the end of input to the shell. IINNPPUUTTRRCC - The filename for the rreeaaddlliinnee startup file, overriding the de- + The filename for the rreeaaddlliinnee startup file, overriding the de- fault of _~_/_._i_n_p_u_t_r_c (see RREEAADDLLIINNEE below). IINNSSIIDDEE__EEMMAACCSS - If this variable appears in the environment when the shell - starts, bbaasshh assumes that it is running inside an Emacs shell - buffer and may disable line editing, depending on the value of + If this variable appears in the environment when the shell + starts, bbaasshh assumes that it is running inside an Emacs shell + buffer and may disable line editing, depending on the value of TTEERRMM. - LLAANNGG Used to determine the locale category for any category not + LLAANNGG Used to determine the locale category for any category not specifically selected with a variable starting with LLCC__. - LLCC__AALLLL This variable overrides the value of LLAANNGG and any other LLCC__ + LLCC__AALLLL This variable overrides the value of LLAANNGG and any other LLCC__ variable specifying a locale category. LLCC__CCOOLLLLAATTEE - 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 se- + 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 se- quences within pathname expansion and pattern matching. LLCC__CCTTYYPPEE - This variable determines the interpretation of characters and - the behavior of character classes within pathname expansion and + This variable determines the interpretation of characters and + the behavior of character classes within pathname expansion and pattern matching. LLCC__MMEESSSSAAGGEESS - This variable determines the locale used to translate double- + This variable determines the locale used to translate double- quoted strings preceded by a $$. LLCC__NNUUMMEERRIICC - This variable determines the locale category used for number + This variable determines the locale category used for number formatting. LLCC__TTIIMMEE - This variable determines the locale category used for data and + This variable determines the locale category used for data and time formatting. - LLIINNEESS Used by the sseelleecctt compound command to determine the column - length for printing selection lists. Automatically set if the - cchheecckkwwiinnssiizzee option is enabled or in an interactive shell upon + LLIINNEESS Used by the sseelleecctt compound command to determine the column + length for printing selection lists. Automatically set if the + cchheecckkwwiinnssiizzee option is enabled or in an interactive shell upon receipt of a SSIIGGWWIINNCCHH. MMAAIILL If the value is set to a file or directory name and the MMAAIILLPPAATTHH - variable is not set, bbaasshh informs the user of the arrival of + variable is not set, bbaasshh informs the user of the arrival of mail in the specified file or Maildir-format directory. MMAAIILLCCHHEECCKK - Specifies how often (in seconds) bbaasshh checks for mail. The de- - fault is 60 seconds. When it is time to check for mail, the - shell does so before displaying the primary prompt. If this - variable is unset, or set to a value that is not a number + Specifies how often (in seconds) bbaasshh checks for mail. The de- + fault is 60 seconds. When it is time to check for mail, the + shell does so before displaying the primary prompt. If this + variable is unset, or set to a value that is not a number greater than or equal to zero, the shell disables mail checking. MMAAIILLPPAATTHH A colon-separated list of filenames to be checked for mail. The message to be printed when mail arrives in a particular file may - be specified by separating the filename from the message with a - "?". When used in the text of the message, $$__ expands to the + be specified by separating the filename from the message with a + "?". When used in the text of the message, $$__ expands to the name of the current mailfile. For example: MMAAIILLPPAATTHH='/var/mail/bfox?"You have mail":~/shell-mail?"$_ has mail!"' - BBaasshh can be configured to supply a default value for this vari- - able (there is no value by default), but the location of the + BBaasshh can be configured to supply a default value for this vari- + able (there is no value by default), but the location of the user mail files that it uses is system dependent (e.g., /var/mail/$$UUSSEERR). OOPPTTEERRRR If set to the value 1, bbaasshh displays error messages generated by - the ggeettooppttss builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). - OOPPTTEERRRR is initialized to 1 each time the shell is invoked or a + the ggeettooppttss builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). + OOPPTTEERRRR is initialized to 1 each time the shell is invoked or a shell script is executed. - PPAATTHH The search path for commands. It is a colon-separated list of - directories in which the shell looks for commands (see CCOOMMMMAANNDD - EEXXEECCUUTTIIOONN below). A zero-length (null) directory name in the + PPAATTHH The search path for commands. It is a colon-separated list of + directories in which the shell looks for commands (see CCOOMMMMAANNDD + EEXXEECCUUTTIIOONN below). A zero-length (null) directory name in the value of PPAATTHH 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 + 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 bbaasshh. A common value is /usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin PPOOSSIIXXLLYY__CCOORRRREECCTT - If this variable is in the environment when bbaasshh starts, the - shell enters posix mode before reading the startup files, as if - the ----ppoossiixx invocation option had been supplied. If it is set - while the shell is running, bbaasshh enables posix mode, as if the + If this variable is in the environment when bbaasshh starts, the + shell enters posix mode before reading the startup files, as if + the ----ppoossiixx invocation option had been supplied. If it is set + while the shell is running, bbaasshh enables posix mode, as if the command "set -o posix" had been executed. When the shell enters posix mode, it sets this variable if it was not already set. PPRROOMMPPTT__CCOOMMMMAANNDD - If this variable is set, and is an array, the value of each set - element is executed as a command prior to issuing each primary - prompt. If this is set but not an array variable, its value is + If this variable is set, and is an array, the value of each set + element is executed as a command prior to issuing each primary + prompt. If this is set but not an array variable, its value is used as a command to execute instead. PPRROOMMPPTT__DDIIRRTTRRIIMM - If set to a number greater than zero, the value is used as the + If set to a number greater than zero, the value is used as the number of trailing directory components to retain when expanding - the \\ww and \\WW prompt string escapes (see PPRROOMMPPTTIINNGG below). + the \\ww and \\WW prompt string escapes (see PPRROOMMPPTTIINNGG below). Characters removed are replaced with an ellipsis. - PPSS00 The value of this parameter is expanded (see PPRROOMMPPTTIINNGG below) - and displayed by interactive shells after reading a command and + PPSS00 The value of this parameter is expanded (see PPRROOMMPPTTIINNGG below) + and displayed by interactive shells after reading a command and before the command is executed. - PPSS11 The value of this parameter is expanded (see PPRROOMMPPTTIINNGG below) - and used as the primary prompt string. The default value is + PPSS11 The value of this parameter is expanded (see PPRROOMMPPTTIINNGG below) + and used as the primary prompt string. The default value is "\s-\v\$ ". - PPSS22 The value of this parameter is expanded as with PPSS11 and used as + PPSS22 The value of this parameter is expanded as with PPSS11 and used as the secondary prompt string. The default is "> ". PPSS33 The value of this parameter is used as the prompt for the sseelleecctt command (see SSHHEELLLL GGRRAAMMMMAARR above). - PPSS44 The value of this parameter is expanded as with PPSS11 and the + PPSS44 The value of this parameter is expanded as with PPSS11 and the value is printed before each command bbaasshh displays during an ex- ecution trace. The first character of the expanded value of PPSS44 is replicated multiple times, as necessary, to indicate multiple levels of indirection. The default is "+ ". - SSHHEELLLL This variable expands to the full pathname to the shell. If it - is not set when the shell starts, bbaasshh assigns to it the full + SSHHEELLLL This variable expands to the full pathname to the shell. If it + is not set when the shell starts, bbaasshh assigns to it the full pathname of the current user's login shell. TTIIMMEEFFOORRMMAATT - The value of this parameter is used as a format string specify- - ing how the timing information for pipelines prefixed with the - ttiimmee reserved word should be displayed. The %% character intro- - duces an escape sequence that is expanded to a time value or - other information. The escape sequences and their meanings are + The value of this parameter is used as a format string specify- + ing how the timing information for pipelines prefixed with the + ttiimmee reserved word should be displayed. The %% character intro- + duces an escape sequence that is expanded to a time value or + other information. The escape sequences and their meanings are as follows; the brackets denote optional portions. %%%% A literal %%. %%[[_p]][[ll]]RR The elapsed time in seconds. @@ -1532,89 +1555,89 @@ PPAARRAAMMEETTEERRSS %%[[_p]][[ll]]SS The number of CPU seconds spent in system mode. %%PP The CPU percentage, computed as (%U + %S) / %R. - The optional _p is a digit specifying the _p_r_e_c_i_s_i_o_n, the number + The optional _p is a digit specifying the _p_r_e_c_i_s_i_o_n, the number of fractional digits after a decimal point. A value of 0 causes - no decimal point or fraction to be output. ttiimmee prints at most - six digits after the decimal point; values of _p greater than 6 + no decimal point or fraction to be output. ttiimmee prints at most + six digits after the decimal point; values of _p greater than 6 are changed to 6. If _p is not specified, ttiimmee prints three dig- its after the decimal point. - The optional ll specifies a longer format, including minutes, of - the form _M_Mm_S_S._F_Fs. The value of _p determines whether or not + The optional ll specifies a longer format, including minutes, of + the form _M_Mm_S_S._F_Fs. The value of _p determines whether or not the fraction is included. - If this variable is not set, bbaasshh acts as if it had the value - $$''\\nnrreeaall\\tt%%33llRR\\nnuusseerr\\tt%%33llUU\\nnssyyss\\tt%%33llSS''. If the value is null, - bbaasshh does not display any timing information. A trailing new- + If this variable is not set, bbaasshh acts as if it had the value + $$''\\nnrreeaall\\tt%%33llRR\\nnuusseerr\\tt%%33llUU\\nnssyyss\\tt%%33llSS''. If the value is null, + bbaasshh does not display any timing information. A trailing new- line is added when the format string is displayed. - TTMMOOUUTT If set to a value greater than zero, the rreeaadd builtin uses the - value as its default timeout. The sseelleecctt command terminates if - input does not arrive after TTMMOOUUTT seconds when input is coming - from a terminal. In an interactive shell, the value is inter- - preted as the number of seconds to wait for a line of input af- - ter issuing the primary prompt. BBaasshh terminates after waiting - for that number of seconds if a complete line of input does not + TTMMOOUUTT If set to a value greater than zero, the rreeaadd builtin uses the + value as its default timeout. The sseelleecctt command terminates if + input does not arrive after TTMMOOUUTT seconds when input is coming + from a terminal. In an interactive shell, the value is inter- + preted as the number of seconds to wait for a line of input af- + ter issuing the primary prompt. BBaasshh terminates after waiting + for that number of seconds if a complete line of input does not arrive. - TTMMPPDDIIRR If set, bbaasshh uses its value as the name of a directory in which + TTMMPPDDIIRR If set, bbaasshh uses its value as the name of a directory in which bbaasshh creates temporary files for the shell's use. aauuttoo__rreessuummee This variable controls how the shell interacts with the user and - job control. If this variable is set, simple commands consist- - ing of only a single word, 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 or containing the word, this selects the most recently ac- - cessed job. The _n_a_m_e of a stopped job, in this context, is the - command line used to start it, as displayed by jjoobbss. If set to - the value _e_x_a_c_t, the word must match the name of a stopped job - exactly; if set to _s_u_b_s_t_r_i_n_g, the word needs to match a sub- - string of the name of a stopped job. The _s_u_b_s_t_r_i_n_g value pro- + job control. If this variable is set, simple commands consist- + ing of only a single word, 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 or containing the word, this selects the most recently ac- + cessed job. The _n_a_m_e of a stopped job, in this context, is the + command line used to start it, as displayed by jjoobbss. If set to + the value _e_x_a_c_t, the word must match the name of a stopped job + exactly; if set to _s_u_b_s_t_r_i_n_g, the word needs to match a sub- + string of the name of a stopped job. The _s_u_b_s_t_r_i_n_g value pro- vides functionality analogous to the %%?? job identifier (see JJOOBB - CCOONNTTRROOLL below). If set to any other value (e.g., _p_r_e_f_i_x), the - word must be a prefix of a stopped job's name; this provides + CCOONNTTRROOLL below). If set to any other value (e.g., _p_r_e_f_i_x), the + word must be a prefix of a stopped job's name; this provides functionality analogous to the %%_s_t_r_i_n_g job identifier. hhiissttcchhaarrss - The two or three characters which control history expansion, - quick substitution, and tokenization (see HHIISSTTOORRYY EEXXPPAANNSSIIOONN be- - low). The first character is the _h_i_s_t_o_r_y _e_x_p_a_n_s_i_o_n character, - the character which begins a history expansion, normally "!!". - The second character is the _q_u_i_c_k _s_u_b_s_t_i_t_u_t_i_o_n character, nor- - mally "^^". When it appears as the first character on the line, + The two or three characters which control history expansion, + quick substitution, and tokenization (see HHIISSTTOORRYY EEXXPPAANNSSIIOONN be- + low). The first character is the _h_i_s_t_o_r_y _e_x_p_a_n_s_i_o_n character, + the character which begins a history expansion, normally "!!". + The second character is the _q_u_i_c_k _s_u_b_s_t_i_t_u_t_i_o_n character, nor- + mally "^^". When it appears as the first character on the line, history substitution repeats the previous command, replacing one - string with another. The optional third character is the _h_i_s_- - _t_o_r_y _c_o_m_m_e_n_t character, normally "##", which indicates that the - remainder of the line is a comment when it appears as the first - character of a word. The history comment character disables - history substitution for the remaining words on the line. It + string with another. The optional third character is the _h_i_s_- + _t_o_r_y _c_o_m_m_e_n_t character, normally "##", which indicates that the + remainder of the line is a comment when it appears as the first + character of a word. The history comment character disables + history substitution 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. AArrrraayyss - BBaasshh provides one-dimensional indexed and associative array variables. - Any variable may be used as an indexed array; the ddeeccllaarree builtin ex- - plicitly declares an array. There is no maximum limit on the size of - an array, nor any requirement that members be indexed or assigned con- - tiguously. Indexed arrays are referenced using arithmetic expressions - that must expand to an integer (see AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN below) and - are zero-based; associative arrays are referenced using arbitrary - strings. Unless otherwise noted, indexed array indices must be non- + BBaasshh provides one-dimensional indexed and associative array variables. + Any variable may be used as an indexed array; the ddeeccllaarree builtin ex- + plicitly declares an array. There is no maximum limit on the size of + an array, nor any requirement that members be indexed or assigned con- + tiguously. Indexed arrays are referenced using arithmetic expressions + that must expand to an integer (see AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN below) and + are zero-based; associative arrays are referenced using arbitrary + strings. Unless otherwise noted, indexed array indices must be non- negative integers. - The shell performs parameter and variable expansion, arithmetic expan- - sion, command substitution, and quote removal on indexed array sub- + The shell performs parameter and variable expansion, arithmetic expan- + sion, command substitution, and quote removal on indexed array sub- scripts. Since this can potentially result in empty strings, subscript indexing treats those as expressions that evaluate to 0. - The shell performs tilde expansion, parameter and variable expansion, - arithmetic expansion, command substitution, and quote removal on asso- - ciative array subscripts. Empty strings cannot be used as associative + The shell performs tilde expansion, parameter and variable expansion, + arithmetic expansion, command substitution, and quote removal on asso- + ciative array subscripts. Empty strings cannot be used as associative array keys. BBaasshh automatically creates an indexed array if any variable is assigned to using the syntax _n_a_m_e[_s_u_b_s_c_r_i_p_t]=_v_a_l_u_e . The _s_u_b_s_c_r_i_p_t is treated as an arithmetic expression that must evaluate - to a number greater than or equal to zero. To explicitly declare an + to a number greater than or equal to zero. To explicitly declare an indexed array, use ddeeccllaarree --aa _n_a_m_e (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). @@ -1629,103 +1652,103 @@ PPAARRAAMMEETTEERRSS rreeaaddoonnllyy builtins. Each attribute applies to all members of an array. Arrays are assigned using compound assignments of the form _n_a_m_e=((value_1 - ... value_n)), where each _v_a_l_u_e may be of the form [_s_u_b_s_c_r_i_p_t]=_s_t_r_i_n_g. - Indexed array assignments do not require anything but _s_t_r_i_n_g. Each - _v_a_l_u_e in the list is expanded using the shell expansions described be- + ... value_n)), where each _v_a_l_u_e may be of the form [_s_u_b_s_c_r_i_p_t]=_s_t_r_i_n_g. + Indexed array assignments do not require anything but _s_t_r_i_n_g. Each + _v_a_l_u_e in the list is expanded using the shell expansions described be- low under EEXXPPAANNSSIIOONN, but _v_a_l_u_es that are valid variable assignments in- - cluding the brackets and subscript do not undergo brace expansion and + cluding the brackets and subscript do not undergo brace expansion and word splitting, as with individual variable assignments. - When assigning to indexed arrays, if the optional brackets and sub- - script are supplied, that index is assigned to; otherwise the index of - the element assigned is the last index assigned to by the statement + When assigning to indexed arrays, if the optional brackets and sub- + script 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. When assigning to an associative array, the words in a compound assign- - ment may be either assignment statements, for which the subscript is - required, or a list of words that is interpreted as a sequence of al- - ternating keys and values: _n_a_m_e=(( _k_e_y_1 _v_a_l_u_e_1 _k_e_y_2 _v_a_l_u_e_2 ...)). These - are treated identically to _n_a_m_e=(( [_k_e_y_1]=_v_a_l_u_e_1 [_k_e_y_2]=_v_a_l_u_e_2 ...)). - The first word in the list determines how the remaining words are in- - terpreted; all assignments in a list must be of the same type. When - using key/value pairs, the keys may not be missing or empty; a final + ment may be either assignment statements, for which the subscript is + required, or a list of words that is interpreted as a sequence of al- + ternating keys and values: _n_a_m_e=(( _k_e_y_1 _v_a_l_u_e_1 _k_e_y_2 _v_a_l_u_e_2 ...)). These + are treated identically to _n_a_m_e=(( [_k_e_y_1]=_v_a_l_u_e_1 [_k_e_y_2]=_v_a_l_u_e_2 ...)). + The first word in the list determines how the remaining words are in- + terpreted; all assignments in a list must be of the same type. When + using key/value pairs, the keys may not be missing or empty; a final missing value is treated like the empty string. - This syntax is also accepted by the ddeeccllaarree builtin. Individual array - elements may be assigned to using the _n_a_m_e[_s_u_b_s_c_r_i_p_t]=_v_a_l_u_e syntax in- + This syntax is also accepted by the ddeeccllaarree builtin. Individual array + elements may be assigned to using the _n_a_m_e[_s_u_b_s_c_r_i_p_t]=_v_a_l_u_e syntax in- troduced above. - When assigning to an indexed array, if _n_a_m_e is subscripted by a nega- + When assigning to an indexed array, if _n_a_m_e is subscripted by a nega- tive number, that number is interpreted as relative to one greater than - the maximum index of _n_a_m_e, so negative indices count back from the end + the maximum index of _n_a_m_e, so negative indices count back from the end of the array, and an index of -1 references the last element. The "+=" operator appends to an array variable when assigning using the compound assignment syntax; see PPAARRAAMMEETTEERRSS above. - An array element is referenced using ${_n_a_m_e[_s_u_b_s_c_r_i_p_t]}. The braces - are required to avoid conflicts with pathname expansion. If _s_u_b_s_c_r_i_p_t + An array element is referenced using ${_n_a_m_e[_s_u_b_s_c_r_i_p_t]}. The braces + are required to avoid conflicts with pathname expansion. If _s_u_b_s_c_r_i_p_t is @@ or **, the word expands to all members of _n_a_m_e, unless noted in the - description of a builtin or word expansion. These subscripts differ - only when the word appears within double quotes. If the word is dou- - ble-quoted, ${_n_a_m_e[*]} expands to a single word with the value of each - array member separated by the first character of the IIFFSS special vari- - able, and ${_n_a_m_e[@]} expands each element of _n_a_m_e to a separate word. + description of a builtin or word expansion. These subscripts differ + only when the word appears within double quotes. If the word is dou- + ble-quoted, ${_n_a_m_e[*]} expands to a single word with the value of each + array member separated by the first character of the IIFFSS special vari- + able, and ${_n_a_m_e[@]} expands each element of _n_a_m_e to a separate word. When there are no array members, ${_n_a_m_e[@]} 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 expansion of - the original word, and the expansion of the last parameter is joined - with the last part of the expansion of the original word. This is - analogous to the expansion of the special parameters ** and @@ (see SSppee-- + double-quoted expansion occurs within a word, the expansion of the + first parameter is joined with the beginning part of the expansion of + the original word, and the expansion of the last parameter is joined + with the last part of the expansion of the original word. This is + analogous to the expansion of the special parameters ** and @@ (see SSppee-- cciiaall PPaarraammeetteerrss above). - ${#_n_a_m_e[_s_u_b_s_c_r_i_p_t]} expands to the length of ${_n_a_m_e[_s_u_b_s_c_r_i_p_t]}. If + ${#_n_a_m_e[_s_u_b_s_c_r_i_p_t]} expands to the length of ${_n_a_m_e[_s_u_b_s_c_r_i_p_t]}. If _s_u_b_s_c_r_i_p_t is ** or @@, the expansion is the number of elements in the ar- ray. If the _s_u_b_s_c_r_i_p_t used to reference an element of an indexed array eval- - uates to a number less than zero, it is interpreted as relative to one - greater than the maximum index of the array, so negative indices count - back from the end of the array, and an index of -1 references the last + uates to a number less than zero, it is interpreted as relative to one + greater than the maximum index of the array, so negative indices count + back from the end of the array, and an index of -1 references the last element. Referencing an array variable without a subscript is equivalent to ref- - erencing the array with a subscript of 0. Any reference to a variable + erencing the array with a subscript of 0. Any reference to a variable using a valid subscript is valid; bbaasshh creates an array if necessary. - An array variable is considered set if a subscript has been assigned a + An array variable is considered set if a subscript has been assigned a value. The null string is a valid value. - It is possible to obtain the keys (indices) of an array as well as the - values. ${!!_n_a_m_e[_@]} and ${!!_n_a_m_e[_*]} expand to the indices assigned in + It is possible to obtain the keys (indices) of an array as well as the + values. ${!!_n_a_m_e[_@]} and ${!!_n_a_m_e[_*]} expand to the indices assigned in array variable _n_a_m_e. The treatment when in double quotes is similar to the expansion of the special parameters _@ and _* within double quotes. The uunnsseett builtin is used to destroy arrays. uunnsseett _n_a_m_e[_s_u_b_s_c_r_i_p_t] un- - sets the array element at index _s_u_b_s_c_r_i_p_t, for both indexed and asso- - ciative arrays. Negative subscripts to indexed arrays are interpreted - as described above. Unsetting the last element of an array variable - does not unset the variable. uunnsseett _n_a_m_e, where _n_a_m_e is an array, re- - moves the entire array. uunnsseett _n_a_m_e[_s_u_b_s_c_r_i_p_t] behaves differently de- - pending on whether _n_a_m_e is an indexed or associative array when _s_u_b_- + sets the array element at index _s_u_b_s_c_r_i_p_t, for both indexed and asso- + ciative arrays. Negative subscripts to indexed arrays are interpreted + as described above. Unsetting the last element of an array variable + does not unset the variable. uunnsseett _n_a_m_e, where _n_a_m_e is an array, re- + moves the entire array. uunnsseett _n_a_m_e[_s_u_b_s_c_r_i_p_t] behaves differently de- + pending on whether _n_a_m_e is an indexed or associative array when _s_u_b_- _s_c_r_i_p_t is ** or @@. If _n_a_m_e is an associative array, this unsets the el- - ement with subscript ** or @@. If _n_a_m_e is an indexed array, unset re- + ement with subscript ** or @@. If _n_a_m_e is an indexed array, unset re- moves all of the elements but does not remove the array itself. - When using a variable name with a subscript as an argument to a com- - mand, such as with uunnsseett, without using the word expansion syntax de- - scribed above, (e.g., unset a[4]), the argument is subject to pathname - expansion. Quote the argument if pathname expansion is not desired + When using a variable name with a subscript as an argument to a com- + mand, such as with uunnsseett, without using the word expansion syntax de- + scribed above, (e.g., unset a[4]), the argument is subject to pathname + expansion. Quote the argument if pathname expansion is not desired (e.g., unset 'a[4]'). - The ddeeccllaarree, llooccaall, and rreeaaddoonnllyy builtins each accept a --aa option to - specify an indexed array and a --AA option to specify an associative ar- - ray. If both options are supplied, --AA takes precedence. The rreeaadd - builtin accepts a --aa option to assign a list of words read from the + The ddeeccllaarree, llooccaall, and rreeaaddoonnllyy builtins each accept a --aa option to + specify an indexed array and a --AA option to specify an associative ar- + ray. If both options are supplied, --AA takes precedence. The rreeaadd + builtin accepts a --aa option to assign a list of words read from the standard input to an array. The sseett and ddeeccllaarree builtins display array - values in a way that allows them to be reused as assignments. Other - builtins accept array name arguments as well (e.g., mmaappffiillee); see the - descriptions of individual builtins below for details. The shell pro- + values in a way that allows them to be reused as assignments. Other + builtins accept array name arguments as well (e.g., mmaappffiillee); see the + descriptions of individual builtins below for details. The shell pro- vides a number of builtin array variables. EEXXPPAANNSSIIOONN @@ -1735,64 +1758,64 @@ EEXXPPAANNSSIIOONN _m_e_t_i_c _e_x_p_a_n_s_i_o_n, _w_o_r_d _s_p_l_i_t_t_i_n_g, _p_a_t_h_n_a_m_e _e_x_p_a_n_s_i_o_n, and _q_u_o_t_e _r_e_m_o_v_a_l. The order of expansions is: brace expansion; tilde expansion, parameter - and variable expansion, arithmetic expansion, and command substitution - (done in a left-to-right fashion); word splitting; pathname expansion; + and variable expansion, arithmetic expansion, and command substitution + (done in a left-to-right fashion); word splitting; pathname expansion; and quote removal. On systems that can support it, there is an additional expansion avail- - able: _p_r_o_c_e_s_s _s_u_b_s_t_i_t_u_t_i_o_n. This is performed at the same time as - tilde, parameter, variable, and arithmetic expansion and command sub- + able: _p_r_o_c_e_s_s _s_u_b_s_t_i_t_u_t_i_o_n. This is performed at the same time as + tilde, parameter, variable, and arithmetic expansion and command sub- stitution. - _Q_u_o_t_e _r_e_m_o_v_a_l is always performed last. It removes quote characters - present in the original word, not ones resulting from one of the other + _Q_u_o_t_e _r_e_m_o_v_a_l is always performed last. It removes quote characters + present in the original word, not ones resulting from one of the other expansions, unless they have been quoted themselves. - Only brace expansion, word splitting, and pathname expansion can in- - crease the number of words of the expansion; other expansions expand a - single word to a single word. The only exceptions to this are the ex- + Only brace expansion, word splitting, and pathname expansion can in- + crease the number of words of the expansion; other expansions expand a + single word to a single word. The only exceptions to this are the ex- pansions of ""$$@@"" and ""$${{_n_a_m_e[[@@]]}}"", and, in most cases, $$** and $${{_n_a_m_e[[**]]}} as explained above (see PPAARRAAMMEETTEERRSS). BBrraaccee EExxppaannssiioonn - _B_r_a_c_e _e_x_p_a_n_s_i_o_n is a mechanism to generate arbitrary strings sharing a + _B_r_a_c_e _e_x_p_a_n_s_i_o_n is a mechanism to generate arbitrary strings sharing a common prefix and suffix, either of which can be empty. This mechanism - is similar to _p_a_t_h_n_a_m_e _e_x_p_a_n_s_i_o_n, but the filenames generated need not - exist. Patterns to be brace expanded are formed from an optional _p_r_e_- - _a_m_b_l_e, followed by either a series of comma-separated strings or a se- - quence expression between a pair of braces, followed by an optional - _p_o_s_t_s_c_r_i_p_t. The preamble is prefixed to each string contained within - the braces, and the postscript is then appended to each resulting + is similar to _p_a_t_h_n_a_m_e _e_x_p_a_n_s_i_o_n, but the filenames generated need not + exist. Patterns to be brace expanded are formed from an optional _p_r_e_- + _a_m_b_l_e, followed by either a series of comma-separated strings or a se- + quence expression between a pair of braces, followed by an optional + _p_o_s_t_s_c_r_i_p_t. 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 + Brace expansions may be nested. The results of each expanded string are not sorted; brace expansion preserves left to right order. For ex- ample, a{{d,c,b}}e expands into "ade ace abe". - A sequence expression takes the form _x...._y[[...._i_n_c_r]], where _x and _y are - either integers or single letters, and _i_n_c_r, an optional increment, is + A sequence expression takes the form _x...._y[[...._i_n_c_r]], where _x and _y are + either integers or single letters, and _i_n_c_r, an optional increment, is an integer. When integers are supplied, the expression expands to each - number between _x and _y, inclusive. If either _x or _y begins with a + number between _x and _y, inclusive. If either _x or _y begins with a zero, each generated term will contain the same number of digits, zero- padding where necessary. When letters are supplied, the expression ex- - pands to each character lexicographically between _x and _y, inclusive, - using the C locale. Note that both _x and _y must be of the same type + pands to each character lexicographically between _x and _y, inclusive, + using the C locale. Note that both _x and _y must be of the same type (integer or letter). When the increment is supplied, it is used as the - difference between each term. The default increment is 1 or -1 as ap- + difference between each term. The default increment is 1 or -1 as ap- propriate. Brace expansion is performed before any other expansions, and any char- - acters special to other expansions are preserved in the result. It is - strictly textual. BBaasshh does not apply any syntactic interpretation to + acters special to other expansions are preserved in the result. It is + strictly textual. BBaasshh does not apply any syntactic interpretation to the context of the expansion or the text between the braces. - A correctly-formed brace expansion must contain unquoted opening and + A correctly-formed brace expansion must contain unquoted opening and closing braces, and at least one unquoted comma or a valid sequence ex- pression. Any incorrectly formed brace expansion is left unchanged. - A "{" or Q , may be quoted with a backslash to prevent its being con- - sidered part of a brace expression. To avoid conflicts with parameter - expansion, the string "${" is not considered eligible for brace expan- + A "{" or Q , may be quoted with a backslash to prevent its being con- + sidered part of a brace expression. To avoid conflicts with parameter + expansion, the string "${" is not considered eligible for brace expan- sion, and inhibits brace expansion until the closing "}". This construct is typically used as shorthand when the common prefix of @@ -1802,67 +1825,67 @@ EEXXPPAANNSSIIOONN or chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}} - Brace expansion introduces a slight incompatibility with historical - versions of sshh. sshh does not treat opening or closing braces specially - when they appear as part of a word, and preserves them in the output. - BBaasshh removes braces from words as a consequence of brace expansion. + Brace expansion introduces a slight incompatibility with historical + versions of sshh. sshh does not treat opening or closing braces specially + when they appear as part of a word, and preserves them in the output. + BBaasshh removes braces from words as a consequence of brace expansion. For example, a word entered to sshh as "file{1,2}" appears identically in the output. BBaasshh outputs that word as "file1 file2" after brace expan- - sion. Start bbaasshh with the ++BB option or disable brace expansion with + sion. Start bbaasshh with the ++BB option or disable brace expansion with the ++BB option to the sseett command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below) for strict sshh compatibility. TTiillddee EExxppaannssiioonn - If a word begins with an unquoted tilde character ("~~"), all of the - characters preceding the first unquoted slash (or all characters, if - there is no unquoted slash) are considered a _t_i_l_d_e_-_p_r_e_f_i_x. 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 _l_o_g_i_n _n_a_m_e. - If this login name is the null string, the tilde is replaced with the + If a word begins with an unquoted tilde character ("~~"), all of the + characters preceding the first unquoted slash (or all characters, if + there is no unquoted slash) are considered a _t_i_l_d_e_-_p_r_e_f_i_x. 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 _l_o_g_i_n _n_a_m_e. + If this login name is the null string, the tilde is replaced with the value of the shell parameter HHOOMMEE. If HHOOMMEE is unset, the tilde expands - to the home directory of the user executing the shell instead. Other- - wise, the tilde-prefix is replaced with the home directory associated + to the home directory of the user executing the shell instead. Other- + wise, the tilde-prefix is replaced with the home directory associated with the specified login name. - If the tilde-prefix is a "~+", the value of the shell variable PPWWDD re- + If the tilde-prefix is a "~+", the value of the shell variable PPWWDD re- places the tilde-prefix. If the tilde-prefix is a "~-", the shell sub- - stitutes the value of the shell variable OOLLDDPPWWDD, if it is set. If the - characters following the tilde in the tilde-prefix consist of a number - _N, optionally prefixed by a "+" or a "-", the tilde-prefix is replaced + stitutes the value of the shell variable OOLLDDPPWWDD, if it is set. If the + characters following the tilde in the tilde-prefix consist of a number + _N, optionally prefixed by a "+" or a "-", the tilde-prefix is replaced with the corresponding element from the directory stack, as it would be displayed by the ddiirrss builtin invoked with the characters following the - tilde in the tilde-prefix as an argument. If the characters following + tilde in the tilde-prefix as an argument. If the characters following the tilde in the tilde-prefix consist of a number without a leading "+" or "-", tilde expansion assumes "+". - The results of tilde expansion are treated as if they were quoted, so - the replacement is not subject to word splitting and pathname expan- + The results of tilde expansion are treated as if they were quoted, so + the replacement is not subject to word splitting and pathname expan- sion. - If the login name is invalid, or the tilde expansion fails, the tilde- + If the login name is invalid, or the tilde expansion fails, the tilde- prefix is unchanged. - BBaasshh checks each variable assignment for unquoted tilde-prefixes imme- - diately following a :: or the first ==, and performs tilde expansion in - these cases. Consequently, one may use filenames with tildes in as- - signments to PPAATTHH, MMAAIILLPPAATTHH, and CCDDPPAATTHH, and the shell assigns the ex- + BBaasshh checks each variable assignment for unquoted tilde-prefixes imme- + diately following a :: or the first ==, and performs tilde expansion in + these cases. Consequently, one may use filenames with tildes in as- + signments to PPAATTHH, MMAAIILLPPAATTHH, and CCDDPPAATTHH, and the shell assigns the ex- panded value. - BBaasshh also performs tilde expansion on words satisfying the conditions + BBaasshh also performs tilde expansion on words satisfying the conditions of variable assignments (as described above under PPAARRAAMMEETTEERRSS) when they - appear as arguments to simple commands. BBaasshh does not do this, except + appear as arguments to simple commands. BBaasshh does not do this, except for the _d_e_c_l_a_r_a_t_i_o_n commands listed above, when in posix mode. PPaarraammeetteerr EExxppaannssiioonn The "$$" character introduces parameter expansion, command substitution, - or arithmetic expansion. The parameter name or symbol to be expanded - may be enclosed in braces, which are optional but serve to protect the - variable to be expanded from characters immediately following it which + or arithmetic expansion. The parameter name or symbol to be expanded + may be enclosed in braces, which are optional but serve to protect the + variable to be expanded from characters immediately following it which could be interpreted as part of the name. - When braces are used, the matching ending brace is the first "}}" not + When braces are used, the matching ending brace is the first "}}" not escaped by a backslash or within a quoted string, and not within an em- - bedded arithmetic expansion, command substitution, or parameter expan- + bedded arithmetic expansion, command substitution, or parameter expan- sion. The basic form of parameter expansion is @@ -1870,127 +1893,127 @@ EEXXPPAANNSSIIOONN ${_p_a_r_a_m_e_t_e_r} which substitutes the value of _p_a_r_a_m_e_t_e_r. The braces are required when - _p_a_r_a_m_e_t_e_r is a positional parameter with more than one digit, or when - _p_a_r_a_m_e_t_e_r is followed by a character which is not to be interpreted as - part of its name. The _p_a_r_a_m_e_t_e_r is a shell parameter as described + _p_a_r_a_m_e_t_e_r is a positional parameter with more than one digit, or when + _p_a_r_a_m_e_t_e_r is followed by a character which is not to be interpreted as + part of its name. The _p_a_r_a_m_e_t_e_r is a shell parameter as described above PPAARRAAMMEETTEERRSS) or an array reference (AArrrraayyss). - If the first character of _p_a_r_a_m_e_t_e_r is an exclamation point (!!), and + If the first character of _p_a_r_a_m_e_t_e_r is an exclamation point (!!), and _p_a_r_a_m_e_t_e_r is not a _n_a_m_e_r_e_f, it introduces a level of indirection. BBaasshh uses the value formed by expanding the rest of _p_a_r_a_m_e_t_e_r as the new _p_a_- - _r_a_m_e_t_e_r; this new parameter is then expanded and that value is used in - the rest of the expansion, rather than the expansion of the original - _p_a_r_a_m_e_t_e_r. This is known as _i_n_d_i_r_e_c_t _e_x_p_a_n_s_i_o_n. The value is subject - to tilde expansion, parameter expansion, command substitution, and - arithmetic expansion. If _p_a_r_a_m_e_t_e_r is a nameref, this expands to the + _r_a_m_e_t_e_r; this new parameter is then expanded and that value is used in + the rest of the expansion, rather than the expansion of the original + _p_a_r_a_m_e_t_e_r. This is known as _i_n_d_i_r_e_c_t _e_x_p_a_n_s_i_o_n. The value is subject + to tilde expansion, parameter expansion, command substitution, and + arithmetic expansion. If _p_a_r_a_m_e_t_e_r is a nameref, this expands to the name of the parameter referenced by _p_a_r_a_m_e_t_e_r instead of performing the complete indirect expansion, for compatibility. The exceptions to this are the expansions of ${!!_p_r_e_f_i_x**} and ${!!_n_a_m_e[_@]} described below. The - exclamation point must immediately follow the left brace in order to + exclamation point must immediately follow the left brace in order to introduce indirection. In each of the cases below, _w_o_r_d is subject to tilde expansion, parame- ter expansion, command substitution, and arithmetic expansion. When not performing substring expansion, using the forms documented be- - low (e.g., ::--), bbaasshh tests for a parameter that is unset or null. + low (e.g., ::--), bbaasshh tests for a parameter that is unset or null. Omitting the colon tests only for a parameter that is unset. ${_p_a_r_a_m_e_t_e_r::--_w_o_r_d} - UUssee DDeeffaauulltt VVaalluueess. If _p_a_r_a_m_e_t_e_r is unset or null, the expan- - sion of _w_o_r_d is substituted. Otherwise, the value of _p_a_r_a_m_e_t_e_r + UUssee DDeeffaauulltt VVaalluueess. If _p_a_r_a_m_e_t_e_r is unset or null, the expan- + sion of _w_o_r_d is substituted. Otherwise, the value of _p_a_r_a_m_e_t_e_r is substituted. ${_p_a_r_a_m_e_t_e_r::==_w_o_r_d} - AAssssiiggnn DDeeffaauulltt VVaalluueess. If _p_a_r_a_m_e_t_e_r is unset or null, the ex- - pansion of _w_o_r_d is assigned to _p_a_r_a_m_e_t_e_r, and the expansion is + AAssssiiggnn DDeeffaauulltt VVaalluueess. If _p_a_r_a_m_e_t_e_r is unset or null, the ex- + pansion of _w_o_r_d is assigned to _p_a_r_a_m_e_t_e_r, and the expansion is the final value of _p_a_r_a_m_e_t_e_r. Positional parameters and special parameters may not be assigned in this way. ${_p_a_r_a_m_e_t_e_r::??_w_o_r_d} - DDiissppllaayy EErrrroorr iiff NNuullll oorr UUnnsseett. If _p_a_r_a_m_e_t_e_r is null or unset, + DDiissppllaayy EErrrroorr iiff NNuullll oorr UUnnsseett. If _p_a_r_a_m_e_t_e_r is null or unset, the shell writes the expansion of _w_o_r_d (or a message to that ef- fect if _w_o_r_d is not present) to the standard error and, if it is - not interactive, exits with a non-zero status. An interactive + not interactive, exits with a non-zero status. An interactive shell does not exit, but does not execute the command associated - with the expansion. Otherwise, the value of _p_a_r_a_m_e_t_e_r is sub- + with the expansion. Otherwise, the value of _p_a_r_a_m_e_t_e_r is sub- stituted. ${_p_a_r_a_m_e_t_e_r::++_w_o_r_d} - UUssee AAlltteerrnnaattee VVaalluuee. If _p_a_r_a_m_e_t_e_r is null or unset, nothing is - substituted, otherwise the expansion of _w_o_r_d is substituted. + UUssee AAlltteerrnnaattee VVaalluuee. If _p_a_r_a_m_e_t_e_r is null or unset, nothing is + substituted, otherwise the expansion of _w_o_r_d is substituted. The value of _p_a_r_a_m_e_t_e_r is not used. ${_p_a_r_a_m_e_t_e_r::_o_f_f_s_e_t} ${_p_a_r_a_m_e_t_e_r::_o_f_f_s_e_t::_l_e_n_g_t_h} - SSuubbssttrriinngg EExxppaannssiioonn. Expands to up to _l_e_n_g_t_h characters of the - value of _p_a_r_a_m_e_t_e_r starting at the character specified by _o_f_f_- - _s_e_t. If _p_a_r_a_m_e_t_e_r is @@ or **, an indexed array subscripted by @@ - or **, or an associative array name, the results differ as de- - scribed below. If ::_l_e_n_g_t_h is omitted (the first form above), + SSuubbssttrriinngg EExxppaannssiioonn. Expands to up to _l_e_n_g_t_h characters of the + value of _p_a_r_a_m_e_t_e_r starting at the character specified by _o_f_f_- + _s_e_t. If _p_a_r_a_m_e_t_e_r is @@ or **, an indexed array subscripted by @@ + or **, or an associative array name, the results differ as de- + scribed below. If ::_l_e_n_g_t_h is omitted (the first form above), this expands to the substring of the value of _p_a_r_a_m_e_t_e_r starting at the character specified by _o_f_f_s_e_t and extending to the end of the value. If _o_f_f_s_e_t is omitted, it is treated as 0. If _l_e_n_g_t_h is omitted, but the colon after _o_f_f_s_e_t is present, it is treated - as 0. _l_e_n_g_t_h and _o_f_f_s_e_t are arithmetic expressions (see AARRIITTHH-- + as 0. _l_e_n_g_t_h and _o_f_f_s_e_t are arithmetic expressions (see AARRIITTHH-- MMEETTIICC EEVVAALLUUAATTIIOONN below). - If _o_f_f_s_e_t evaluates to a number less than zero, the value is + If _o_f_f_s_e_t evaluates to a number less than zero, the value is used as an offset in characters from the end of the value of _p_a_- - _r_a_m_e_t_e_r. If _l_e_n_g_t_h evaluates to a number less than zero, it is + _r_a_m_e_t_e_r. If _l_e_n_g_t_h evaluates to a number less than zero, it is interpreted as an offset in characters from the end of the value - of _p_a_r_a_m_e_t_e_r rather than a number of characters, and the expan- - sion is the characters between _o_f_f_s_e_t and that result. Note - that a negative offset must be separated from the colon by at + of _p_a_r_a_m_e_t_e_r rather than a number of characters, and the expan- + sion is the characters between _o_f_f_s_e_t and that result. Note + that a negative offset must be separated from the colon by at least one space to avoid being confused with the ::-- expansion. - If _p_a_r_a_m_e_t_e_r is @@ or **, the result is _l_e_n_g_t_h positional parame- - ters beginning at _o_f_f_s_e_t. A negative _o_f_f_s_e_t is taken relative - to one greater than the greatest positional parameter, so an + If _p_a_r_a_m_e_t_e_r is @@ or **, the result is _l_e_n_g_t_h positional parame- + ters beginning at _o_f_f_s_e_t. A negative _o_f_f_s_e_t is taken relative + to one greater than the greatest positional parameter, so an offset of -1 evaluates to the last positional parameter (or 0 if - there are no positional parameters). It is an expansion error + there are no positional parameters). It is an expansion error if _l_e_n_g_t_h evaluates to a number less than zero. If _p_a_r_a_m_e_t_e_r is an indexed array name subscripted by @ or *, the result is the _l_e_n_g_t_h members of the array beginning with ${_p_a_r_a_- - _m_e_t_e_r[_o_f_f_s_e_t]}. A negative _o_f_f_s_e_t is taken relative to one + _m_e_t_e_r[_o_f_f_s_e_t]}. A negative _o_f_f_s_e_t is taken relative to one greater than the maximum index of the specified array. It is an expansion error if _l_e_n_g_t_h evaluates to a number less than zero. Substring expansion applied to an associative array produces un- defined results. - Substring indexing is zero-based unless the positional parame- - ters are used, in which case the indexing starts at 1 by de- - fault. If _o_f_f_s_e_t is 0, and the positional parameters are used, + Substring indexing is zero-based unless the positional parame- + ters are used, in which case the indexing starts at 1 by de- + fault. If _o_f_f_s_e_t is 0, and the positional parameters are used, $$00 is prefixed to the list. ${!!_p_r_e_f_i_x**} ${!!_p_r_e_f_i_x@@} - NNaammeess mmaattcchhiinngg pprreeffiixx. Expands to the names of variables whose + NNaammeess mmaattcchhiinngg pprreeffiixx. Expands to the names of variables whose names begin with _p_r_e_f_i_x, separated by the first character of the - IIFFSS special variable. When _@ is used and the expansion appears - within double quotes, each variable name expands to a separate + IIFFSS special variable. When _@ is used and the expansion appears + within double quotes, each variable name expands to a separate word. ${!!_n_a_m_e[_@]} ${!!_n_a_m_e[_*]} - LLiisstt ooff aarrrraayy kkeeyyss. If _n_a_m_e is an array variable, expands to - the list of array indices (keys) assigned in _n_a_m_e. If _n_a_m_e is - not an array, expands to 0 if _n_a_m_e is set and null otherwise. - When _@ is used and the expansion appears within double quotes, + LLiisstt ooff aarrrraayy kkeeyyss. If _n_a_m_e is an array variable, expands to + the list of array indices (keys) assigned in _n_a_m_e. If _n_a_m_e is + not an array, expands to 0 if _n_a_m_e is set and null otherwise. + When _@ is used and the expansion appears within double quotes, each key expands to a separate word. ${##_p_a_r_a_m_e_t_e_r} - PPaarraammeetteerr lleennggtthh. Substitutes the length in characters of the - expanded value of _p_a_r_a_m_e_t_e_r. If _p_a_r_a_m_e_t_e_r is ** or @@, the value - substituted is the number of positional parameters. If _p_a_r_a_m_e_- - _t_e_r is an array name subscripted by ** or @@, the value substi- - tuted is the number of elements in the array. If _p_a_r_a_m_e_t_e_r is - an indexed array name subscripted by a negative number, that - number is interpreted as relative to one greater than the maxi- - mum index of _p_a_r_a_m_e_t_e_r, so negative indices count back from the - end of the array, and an index of -1 references the last ele- + PPaarraammeetteerr lleennggtthh. Substitutes the length in characters of the + expanded value of _p_a_r_a_m_e_t_e_r. If _p_a_r_a_m_e_t_e_r is ** or @@, the value + substituted is the number of positional parameters. If _p_a_r_a_m_e_- + _t_e_r is an array name subscripted by ** or @@, the value substi- + tuted is the number of elements in the array. If _p_a_r_a_m_e_t_e_r is + an indexed array name subscripted by a negative number, that + number is interpreted as relative to one greater than the maxi- + mum index of _p_a_r_a_m_e_t_e_r, so negative indices count back from the + end of the array, and an index of -1 references the last ele- ment. ${_p_a_r_a_m_e_t_e_r##_w_o_r_d} @@ -1998,15 +2021,15 @@ EEXXPPAANNSSIIOONN RReemmoovvee mmaattcchhiinngg pprreeffiixx ppaatttteerrnn. The _w_o_r_d is expanded to produce a pattern just as in pathname expansion, and matched against the expanded value of _p_a_r_a_m_e_t_e_r using the rules described under PPaatt-- - tteerrnn MMaattcchhiinngg below. If the pattern matches the beginning of - the value of _p_a_r_a_m_e_t_e_r, then the result of the expansion is the - expanded value of _p_a_r_a_m_e_t_e_r with the shortest matching pattern - (the "#" case) or the longest matching pattern (the "##" case) - deleted. If _p_a_r_a_m_e_t_e_r is @@ or **, the pattern removal operation - is applied to each positional parameter in turn, and the expan- - sion is the resultant list. If _p_a_r_a_m_e_t_e_r is an array variable - subscripted with @@ or **, the pattern removal operation is ap- - plied to each member of the array in turn, and the expansion is + tteerrnn MMaattcchhiinngg below. If the pattern matches the beginning of + the value of _p_a_r_a_m_e_t_e_r, then the result of the expansion is the + expanded value of _p_a_r_a_m_e_t_e_r with the shortest matching pattern + (the "#" case) or the longest matching pattern (the "##" case) + deleted. If _p_a_r_a_m_e_t_e_r is @@ or **, the pattern removal operation + is applied to each positional parameter in turn, and the expan- + sion is the resultant list. If _p_a_r_a_m_e_t_e_r is an array variable + subscripted with @@ or **, the pattern removal operation is ap- + plied to each member of the array in turn, and the expansion is the resultant list. ${_p_a_r_a_m_e_t_e_r%%_w_o_r_d} @@ -2014,15 +2037,15 @@ EEXXPPAANNSSIIOONN RReemmoovvee mmaattcchhiinngg ssuuffffiixx ppaatttteerrnn. The _w_o_r_d is expanded to produce a pattern just as in pathname expansion, and matched against the expanded value of _p_a_r_a_m_e_t_e_r using the rules described under PPaatt-- - tteerrnn MMaattcchhiinngg below. If the pattern matches a trailing portion - of the expanded value of _p_a_r_a_m_e_t_e_r, then the result of the ex- - pansion is the expanded value of _p_a_r_a_m_e_t_e_r with the shortest - matching pattern (the "%" case) or the longest matching pattern - (the "%%" case) deleted. If _p_a_r_a_m_e_t_e_r is @@ or **, the pattern - removal operation is applied to each positional parameter in - turn, and the expansion is the resultant list. If _p_a_r_a_m_e_t_e_r is - an array variable subscripted with @@ or **, the pattern removal - operation is applied to each member of the array in turn, and + tteerrnn MMaattcchhiinngg below. If the pattern matches a trailing portion + of the expanded value of _p_a_r_a_m_e_t_e_r, then the result of the ex- + pansion is the expanded value of _p_a_r_a_m_e_t_e_r with the shortest + matching pattern (the "%" case) or the longest matching pattern + (the "%%" case) deleted. If _p_a_r_a_m_e_t_e_r is @@ or **, the pattern + removal operation is applied to each positional parameter in + turn, and the expansion is the resultant list. If _p_a_r_a_m_e_t_e_r is + an array variable subscripted with @@ or **, the pattern removal + operation is applied to each member of the array in turn, and the expansion is the resultant list. ${_p_a_r_a_m_e_t_e_r//_p_a_t_t_e_r_n//_s_t_r_i_n_g} @@ -2030,128 +2053,128 @@ EEXXPPAANNSSIIOONN ${_p_a_r_a_m_e_t_e_r//##_p_a_t_t_e_r_n//_s_t_r_i_n_g} ${_p_a_r_a_m_e_t_e_r//%%_p_a_t_t_e_r_n//_s_t_r_i_n_g} PPaatttteerrnn ssuubbssttiittuuttiioonn. The _p_a_t_t_e_r_n is expanded to produce a pat- - tern and matched against the expanded value of _p_a_r_a_m_e_t_e_r as de- + tern and matched against the expanded value of _p_a_r_a_m_e_t_e_r as de- scribed under PPaatttteerrnn MMaattcchhiinngg below. The longest match of _p_a_t_- - _t_e_r_n in the expanded value is replaced with _s_t_r_i_n_g. _s_t_r_i_n_g un- + _t_e_r_n in the expanded value is replaced with _s_t_r_i_n_g. _s_t_r_i_n_g un- dergoes tilde expansion, parameter and variable expansion, - arithmetic expansion, command and process substitution, and + arithmetic expansion, command and process substitution, and quote removal. - In the first form above, only the first match is replaced. If + In the first form above, only the first match is replaced. If there are two slashes separating _p_a_r_a_m_e_t_e_r and _p_a_t_t_e_r_n (the sec- - ond form above), all matches of _p_a_t_t_e_r_n are replaced with - _s_t_r_i_n_g. If _p_a_t_t_e_r_n is preceded by ## (the third form above), it - must match at the beginning of the expanded value of _p_a_r_a_m_e_t_e_r. - If _p_a_t_t_e_r_n is preceded by %% (the fourth form above), it must + ond form above), all matches of _p_a_t_t_e_r_n are replaced with + _s_t_r_i_n_g. If _p_a_t_t_e_r_n is preceded by ## (the third form above), it + must match at the beginning of the expanded value of _p_a_r_a_m_e_t_e_r. + If _p_a_t_t_e_r_n is preceded by %% (the fourth form above), it must match at the end of the expanded value of _p_a_r_a_m_e_t_e_r. - If the expansion of _s_t_r_i_n_g is null, matches of _p_a_t_t_e_r_n are + If the expansion of _s_t_r_i_n_g is null, matches of _p_a_t_t_e_r_n are deleted and the // following _p_a_t_t_e_r_n may be omitted. - If the ppaattssuubb__rreeppllaacceemmeenntt shell option is enabled using sshhoopptt, - any unquoted instances of && in _s_t_r_i_n_g are replaced with the + If the ppaattssuubb__rreeppllaacceemmeenntt shell option is enabled using sshhoopptt, + any unquoted instances of && in _s_t_r_i_n_g are replaced with the matching portion of _p_a_t_t_e_r_n. Quoting any part of _s_t_r_i_n_g inhibits replacement in the expansion - of the quoted portion, including replacement strings stored in - shell variables. Backslash escapes && in _s_t_r_i_n_g; the backslash - is removed in order to permit a literal && in the replacement - string. Backslash can also be used to escape a backslash; \\\\ + of the quoted portion, including replacement strings stored in + shell variables. Backslash escapes && in _s_t_r_i_n_g; the backslash + is removed in order to permit a literal && in the replacement + string. Backslash can also be used to escape a backslash; \\\\ results in a literal backslash in the replacement. Users should - take care if _s_t_r_i_n_g is double-quoted to avoid unwanted interac- - tions between the backslash and double-quoting, since backslash - has special meaning within double quotes. Pattern substitution - performs the check for unquoted && after expanding _s_t_r_i_n_g; shell - programmers should quote any occurrences of && they want to be + take care if _s_t_r_i_n_g is double-quoted to avoid unwanted interac- + tions between the backslash and double-quoting, since backslash + has special meaning within double quotes. Pattern substitution + performs the check for unquoted && after expanding _s_t_r_i_n_g; shell + programmers should quote any occurrences of && they want to be taken literally in the replacement and ensure any instances of && they want to be replaced are unquoted. - Like the pattern removal operators, double quotes surrounding + Like the pattern removal operators, double quotes surrounding the replacement string quote the expanded characters, while dou- - ble quotes enclosing the entire parameter substitution do not, - since the expansion is performed in a context that doesn't take + ble quotes enclosing the entire parameter substitution do not, + since the expansion is performed in a context that doesn't take any enclosing double quotes into account. - If the nnooccaasseemmaattcchh shell option is enabled, the match is per- + If the nnooccaasseemmaattcchh shell option is enabled, the match is per- formed without regard to the case of alphabetic characters. If _p_a_r_a_m_e_t_e_r is @@ or **, the substitution operation is applied to - each positional parameter in turn, and the expansion is the re- - sultant list. If _p_a_r_a_m_e_t_e_r is an array variable subscripted - with @@ or **, the substitution operation is applied to each mem- - ber of the array in turn, and the expansion is the resultant + each positional parameter in turn, and the expansion is the re- + sultant list. If _p_a_r_a_m_e_t_e_r is an array variable subscripted + with @@ or **, the substitution operation is applied to each mem- + ber of the array in turn, and the expansion is the resultant list. ${_p_a_r_a_m_e_t_e_r^^_p_a_t_t_e_r_n} ${_p_a_r_a_m_e_t_e_r^^^^_p_a_t_t_e_r_n} ${_p_a_r_a_m_e_t_e_r,,_p_a_t_t_e_r_n} ${_p_a_r_a_m_e_t_e_r,,,,_p_a_t_t_e_r_n} - CCaassee mmooddiiffiiccaattiioonn. This expansion modifies the case of alpha- - betic characters in _p_a_r_a_m_e_t_e_r. First, the _p_a_t_t_e_r_n is expanded - to produce a pattern as described below under PPaatttteerrnn MMaattcchhiinngg. + CCaassee mmooddiiffiiccaattiioonn. This expansion modifies the case of alpha- + betic characters in _p_a_r_a_m_e_t_e_r. First, the _p_a_t_t_e_r_n is expanded + to produce a pattern as described below under PPaatttteerrnn MMaattcchhiinngg. BBaasshh then examines characters in the expanded value of _p_a_r_a_m_e_t_e_r - against _p_a_t_t_e_r_n as described below. If a character matches the - pattern, its case is converted. The pattern should not attempt + against _p_a_t_t_e_r_n as described below. If a character matches the + pattern, its case is converted. The pattern should not attempt to match more than one character. - Using "^" converts lowercase letters matching _p_a_t_t_e_r_n to upper- + Using "^" converts lowercase letters matching _p_a_t_t_e_r_n to upper- case; "," converts matching uppercase letters to lowercase. The - ^^ and ,, variants examine the first character in the expanded - value and convert its case if it matches _p_a_t_t_e_r_n; the ^^^^ and ,,,, - variants examine all characters in the expanded value and con- - vert each one that matches _p_a_t_t_e_r_n. If _p_a_t_t_e_r_n is omitted, it + ^^ and ,, variants examine the first character in the expanded + value and convert its case if it matches _p_a_t_t_e_r_n; the ^^^^ and ,,,, + variants examine all characters in the expanded value and con- + vert each one that matches _p_a_t_t_e_r_n. If _p_a_t_t_e_r_n is omitted, it is treated like a ??, which matches every character. - If _p_a_r_a_m_e_t_e_r is @@ or **, the case modification operation is ap- + If _p_a_r_a_m_e_t_e_r is @@ or **, the case modification operation is ap- plied to each positional parameter in turn, and the expansion is - the resultant list. If _p_a_r_a_m_e_t_e_r is an array variable sub- + the resultant list. If _p_a_r_a_m_e_t_e_r is an array variable sub- scripted with @@ or **, the case modification operation is applied - to each member of the array in turn, and the expansion is the + to each member of the array in turn, and the expansion is the resultant list. ${_p_a_r_a_m_e_t_e_r@@_o_p_e_r_a_t_o_r} PPaarraammeetteerr ttrraannssffoorrmmaattiioonn. The expansion is either a transforma- - tion of the value of _p_a_r_a_m_e_t_e_r or information about _p_a_r_a_m_e_t_e_r - itself, depending on the value of _o_p_e_r_a_t_o_r. Each _o_p_e_r_a_t_o_r is a + tion of the value of _p_a_r_a_m_e_t_e_r or information about _p_a_r_a_m_e_t_e_r + itself, depending on the value of _o_p_e_r_a_t_o_r. Each _o_p_e_r_a_t_o_r is a single letter: - UU The expansion is a string that is the value of _p_a_r_a_m_e_t_e_r - with lowercase alphabetic characters converted to upper- + UU The expansion is a string that is the value of _p_a_r_a_m_e_t_e_r + with lowercase alphabetic characters converted to upper- case. - uu The expansion is a string that is the value of _p_a_r_a_m_e_t_e_r + uu The expansion is a string that is the value of _p_a_r_a_m_e_t_e_r with the first character converted to uppercase, if it is alphabetic. - LL The expansion is a string that is the value of _p_a_r_a_m_e_t_e_r - with uppercase alphabetic characters converted to lower- + LL The expansion is a string that is the value of _p_a_r_a_m_e_t_e_r + with uppercase alphabetic characters converted to lower- case. - QQ The expansion is a string that is the value of _p_a_r_a_m_e_t_e_r + QQ The expansion is a string that is the value of _p_a_r_a_m_e_t_e_r quoted in a format that can be reused as input. - EE The expansion is a string that is the value of _p_a_r_a_m_e_t_e_r - with backslash escape sequences expanded as with the + EE The expansion is a string that is the value of _p_a_r_a_m_e_t_e_r + with backslash escape sequences expanded as with the $$''...'' quoting mechanism. PP The expansion is a string that is the result of expanding the value of _p_a_r_a_m_e_t_e_r as if it were a prompt string (see PPRROOMMPPTTIINNGG below). - AA The expansion is a string in the form of an assignment - statement or ddeeccllaarree command that, if evaluated, recre- + AA The expansion is a string in the form of an assignment + statement or ddeeccllaarree command that, if evaluated, recre- ates _p_a_r_a_m_e_t_e_r with its attributes and value. - KK Produces a possibly-quoted version of the value of _p_a_r_a_- - _m_e_t_e_r, except that it prints the values of indexed and - associative arrays as a sequence of quoted key-value + KK Produces a possibly-quoted version of the value of _p_a_r_a_- + _m_e_t_e_r, except that it prints the values of indexed and + associative arrays as a sequence of quoted key-value pairs (see AArrrraayyss above). The keys and values are quoted in a format that can be reused as input. - aa The expansion is a string consisting of flag values rep- + aa The expansion is a string consisting of flag values rep- resenting _p_a_r_a_m_e_t_e_r's attributes. - kk Like the K transformation, but expands the keys and val- - ues of indexed and associative arrays to separate words + kk Like the K transformation, but expands the keys and val- + ues of indexed and associative arrays to separate words after word splitting. - If _p_a_r_a_m_e_t_e_r is @@ or **, the operation is applied to each posi- - tional parameter in turn, and the expansion is the resultant - list. If _p_a_r_a_m_e_t_e_r is an array variable subscripted with @@ or + If _p_a_r_a_m_e_t_e_r is @@ or **, the operation is applied to each posi- + tional parameter in turn, and the expansion is the resultant + list. If _p_a_r_a_m_e_t_e_r is an array variable subscripted with @@ or **, the operation is applied to each member of the array in turn, and the expansion is the resultant list. - The result of the expansion is subject to word splitting and + The result of the expansion is subject to word splitting and pathname expansion as described below. CCoommmmaanndd SSuubbssttiittuuttiioonn @@ -2165,46 +2188,46 @@ EEXXPPAANNSSIIOONN BBaasshh performs the expansion by executing _c_o_m_m_a_n_d in a subshell environ- ment 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 com- - mand substitution $$((ccaatt _f_i_l_e)) can be replaced by the equivalent but + not deleted, but they may be removed during word splitting. The com- + mand substitution $$((ccaatt _f_i_l_e)) can be replaced by the equivalent but faster $$((<< _f_i_l_e)). - With the old-style backquote form of substitution, backslash retains - its literal meaning except when followed by $$, ``, or \\. The first - backquote not preceded by a backslash terminates the command substitu- - tion. When using the $(_c_o_m_m_a_n_d) form, all characters between the + With the old-style backquote form of substitution, backslash retains + its literal meaning except when followed by $$, ``, or \\. The first + backquote not preceded by a backslash terminates the command substitu- + tion. When using the $(_c_o_m_m_a_n_d) form, all characters between the parentheses make up the command; none are treated specially. There is an alternate form of command substitution: $${{_c _c_o_m_m_a_n_d;;}} - which executes _c_o_m_m_a_n_d in the current execution environment and cap- + which executes _c_o_m_m_a_n_d in the current execution environment and cap- tures its output, again with trailing newlines removed. The character _c following the open brace must be a space, tab, newline, - or ||, and the close brace must be in a position where a reserved word - may appear (i.e., preceded by a command terminator such as semicolon). + or ||, and the close brace must be in a position where a reserved word + may appear (i.e., preceded by a command terminator such as semicolon). BBaasshh allows the close brace to be joined to the remaining characters in - the word without being followed by a shell metacharacter as a reserved + the word without being followed by a shell metacharacter as a reserved word would usually require. Any side effects of _c_o_m_m_a_n_d take effect immediately in the current exe- - cution environment and persist in the current environment after the + cution environment and persist in the current environment after the command completes (e.g., the eexxiitt builtin exits the shell). - This type of command substitution superficially resembles executing an - unnamed shell function: local variables are created as when a shell - function is executing, and the rreettuurrnn builtin forces _c_o_m_m_a_n_d to com- - plete; however, the rest of the execution environment, including the + This type of command substitution superficially resembles executing an + unnamed shell function: local variables are created as when a shell + function is executing, and the rreettuurrnn builtin forces _c_o_m_m_a_n_d to com- + plete; however, the rest of the execution environment, including the positional parameters, is shared with the caller. - If the first character following the open brace is a ||, the construct - expands to the value of the RREEPPLLYY shell variable after _c_o_m_m_a_n_d exe- - cutes, without removing any trailing newlines, and the standard output - of _c_o_m_m_a_n_d remains the same as in the calling shell. BBaasshh creates RREE-- + If the first character following the open brace is a ||, the construct + expands to the value of the RREEPPLLYY shell variable after _c_o_m_m_a_n_d exe- + cutes, without removing any trailing newlines, and the standard output + of _c_o_m_m_a_n_d remains the same as in the calling shell. BBaasshh creates RREE-- PPLLYY as an initially-unset local variable when _c_o_m_m_a_n_d executes, and re- - stores RREEPPLLYY to the value it had before the command substitution after + stores RREEPPLLYY to the value it had before the command substitution after _c_o_m_m_a_n_d completes, as with any local variable. Command substitutions may be nested. To nest when using the backquoted @@ -2219,197 +2242,197 @@ EEXXPPAANNSSIIOONN $$((((_e_x_p_r_e_s_s_i_o_n)))) - The _e_x_p_r_e_s_s_i_o_n undergoes the same expansions as if it were within dou- + The _e_x_p_r_e_s_s_i_o_n undergoes the same expansions as if it were within dou- ble quotes, but unescaped double quote characters in _e_x_p_r_e_s_s_i_o_n are not - treated specially and are removed. All tokens in the expression un- + treated specially and are removed. All tokens in the expression un- dergo parameter and variable expansion, command substitution, and quote - removal. The result is treated as the arithmetic expression to be - evaluated. Since the way Bash handles double quotes can potentially - result in empty strings, arithmetic expansion treats those as expres- + removal. The result is treated as the arithmetic expression to be + evaluated. Since the way Bash handles double quotes can potentially + result in empty strings, arithmetic expansion treats those as expres- sions that evaluate to 0. Arithmetic expansions may be nested. - The evaluation is performed according to the rules listed below under + The evaluation is performed according to the rules listed below under AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN. If _e_x_p_r_e_s_s_i_o_n is invalid, bbaasshh prints a message - to standard error indicating failure, does not perform the substitu- + to standard error indicating failure, does not perform the substitu- tion, and does not execute the command associated with the expansion. PPrroocceessss SSuubbssttiittuuttiioonn - _P_r_o_c_e_s_s _s_u_b_s_t_i_t_u_t_i_o_n allows a process's input or output to be referred - to using a filename. It takes the form of <<((_l_i_s_t)) or >>((_l_i_s_t)). The - process _l_i_s_t is run asynchronously, and its input or output appears as + _P_r_o_c_e_s_s _s_u_b_s_t_i_t_u_t_i_o_n allows a process's input or output to be referred + to using a filename. It takes the form of <<((_l_i_s_t)) or >>((_l_i_s_t)). The + process _l_i_s_t is run asynchronously, and its input or output appears as a filename. This filename is passed as an argument to the current com- mand as the result of the expansion. - If the >>((_l_i_s_t)) form is used, writing to the file provides input for + If the >>((_l_i_s_t)) form is used, writing to the file provides input for _l_i_s_t. If the <<((_l_i_s_t)) form is used, reading the file obtains the output of _l_i_s_t. No space may appear between the << or >> and the left parenthe- sis, otherwise the construct would be interpreted as a redirection. - Process substitution is supported on systems that support named pipes + Process substitution is supported on systems that support named pipes (_F_I_F_O_s) or the _/_d_e_v_/_f_d method of naming open files. - When available, process substitution is performed simultaneously with - parameter and variable expansion, command substitution, and arithmetic + When available, process substitution is performed simultaneously with + parameter and variable expansion, command substitution, and arithmetic expansion. WWoorrdd SSpplliittttiinngg - The shell scans the results of parameter expansion, command substitu- - tion, and arithmetic expansion that did not occur within double quotes + The shell scans the results of parameter expansion, command substitu- + tion, and arithmetic expansion that did not occur within double quotes for _w_o_r_d _s_p_l_i_t_t_i_n_g. Words that were not expanded are not split. - The shell treats each character of IIFFSS as a delimiter, and splits the - results of the other expansions into words using these characters as + The shell treats each character of IIFFSS as a delimiter, and splits the + results of the other expansions into words using these characters as field terminators. An _I_F_S _w_h_i_t_e_s_p_a_c_e character is whitespace as defined above (see DDeeffiinnii-- - ttiioonnss) that appears in the value of IIFFSS. Space, tab, and newline are - always considered IFS whitespace, even if they don't appear in the lo- + ttiioonnss) that appears in the value of IIFFSS. Space, tab, and newline are + always considered IFS whitespace, even if they don't appear in the lo- cale's ssppaaccee category. - If IIFFSS is unset, field splitting acts as if its value were - <><><>, and treats these characters as IFS whitespace. - If the value of IIFFSS is null, no word splitting occurs, but implicit + If IIFFSS is unset, field splitting acts as if its value were + <><><>, and treats these characters as IFS whitespace. + If the value of IIFFSS is null, no word splitting occurs, but implicit null arguments (see below) are still removed. - Word splitting begins by removing sequences of IFS whitespace charac- - ters from the beginning and end of the results of the previous expan- + Word splitting begins by removing sequences of IFS whitespace charac- + ters from the beginning and end of the results of the previous expan- sions, then splits the remaining words. - If the value of IIFFSS consists solely of IFS whitespace, any sequence of - IFS whitespace characters delimits a field, so a field consists of + If the value of IIFFSS consists solely of IFS whitespace, any sequence of + IFS whitespace characters delimits a field, so a field consists of characters that are not unquoted IFS whitespace, and null fields result only from quoting. - If IIFFSS contains a non-whitespace character, then any character in the - value of IIFFSS that is not IFS whitespace, along with any adjacent IFS + If IIFFSS contains a non-whitespace character, then any character in the + value of IIFFSS that is not IFS whitespace, along with any adjacent IFS whitespace characters, delimits a field. This means that adjacent non- - IFS-whitespace delimiters produce a null field. A sequence of IFS + IFS-whitespace delimiters produce a null field. A sequence of IFS whitespace characters also delimits a field. - Explicit null arguments ("""" or '''') are retained and passed to commands + Explicit null arguments ("""" or '''') are retained and passed to commands as empty strings. Unquoted implicit null arguments, resulting from the - expansion of parameters that have no values, are removed. Expanding a - parameter with no value within double quotes produces a null field, + expansion of parameters that have no values, are removed. Expanding a + parameter with no value within double quotes produces a null field, which is retained and passed to a command as an empty string. - When a quoted null argument appears as part of a word whose expansion - is non-null, word splitting removes the null argument portion, leaving - the non-null expansion. That is, the word "-d''" becomes "-d" after + When a quoted null argument appears as part of a word whose expansion + is non-null, word splitting removes the null argument portion, leaving + the non-null expansion. That is, the word "-d''" becomes "-d" after word splitting and null argument removal. PPaatthhnnaammee EExxppaannssiioonn - After word splitting, unless the --ff option has been set, bbaasshh scans - each word for the characters **, ??, and [[. If one of these characters + After word splitting, unless the --ff option has been set, bbaasshh scans + each word for the characters **, ??, and [[. If one of these characters appears, and is not quoted, then the word is regarded as a _p_a_t_t_e_r_n, and replaced with a sorted list of filenames matching the pattern (see PPaatt-- - tteerrnn MMaattcchhiinngg below) subject to the value of the GGLLOOBBSSOORRTT shell vari- + tteerrnn MMaattcchhiinngg below) subject to the value of the GGLLOOBBSSOORRTT shell vari- able. - If no matching filenames are found, and the shell option nnuullllgglloobb is - not enabled, the word is left unchanged. If the nnuullllgglloobb option is - set, and no matches are found, the word is removed. If the ffaaiillgglloobb - shell option is set, and no matches are found, bbaasshh prints an error - message and does not execute the command. If the shell option nnooccaassee-- - gglloobb is enabled, the match is performed without regard to the case of + If no matching filenames are found, and the shell option nnuullllgglloobb is + not enabled, the word is left unchanged. If the nnuullllgglloobb option is + set, and no matches are found, the word is removed. If the ffaaiillgglloobb + shell option is set, and no matches are found, bbaasshh prints an error + message and does not execute the command. If the shell option nnooccaassee-- + gglloobb is enabled, the match is performed without regard to the case of alphabetic characters. When a pattern is used for pathname expansion, the character "." at the - start of a name or immediately following a slash must be matched ex- - plicitly, unless the shell option ddoottgglloobb is set. In order to match - the filenames _. and _._., the pattern must begin with "." (for example, + start of a name or immediately following a slash must be matched ex- + plicitly, unless the shell option ddoottgglloobb is set. In order to match + the filenames _. and _._., the pattern must begin with "." (for example, ".?"), even if ddoottgglloobb is set. If the gglloobbsskkiippddoottss shell option is en- - abled, the filenames _. and _._. never match, even if the pattern begins - with a ".". When not matching pathnames, the "." character is not + abled, the filenames _. and _._. never match, even if the pattern begins + with a ".". When not matching pathnames, the "." character is not treated specially. - When matching a pathname, the slash character must always be matched + When matching a pathname, the slash character must always be matched explicitly by a slash in the pattern, but in other matching contexts it - can be matched by a special pattern character as described below under + can be matched by a special pattern character as described below under PPaatttteerrnn MMaattcchhiinngg. - See the description of sshhoopptt below under SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS for a - description of the nnooccaasseegglloobb, nnuullllgglloobb, gglloobbsskkiippddoottss, ffaaiillgglloobb, and + See the description of sshhoopptt below under SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS for a + description of the nnooccaasseegglloobb, nnuullllgglloobb, gglloobbsskkiippddoottss, ffaaiillgglloobb, and ddoottgglloobb shell options. - The GGLLOOBBIIGGNNOORREE shell variable may be used to restrict the set of file - names matching a _p_a_t_t_e_r_n. If GGLLOOBBIIGGNNOORREE is set, each matching file - name that also matches one of the patterns in GGLLOOBBIIGGNNOORREE is removed - from the list of matches. If the nnooccaasseegglloobb option is set, the match- - ing against the patterns in GGLLOOBBIIGGNNOORREE is performed without regard to + The GGLLOOBBIIGGNNOORREE shell variable may be used to restrict the set of file + names matching a _p_a_t_t_e_r_n. If GGLLOOBBIIGGNNOORREE is set, each matching file + name that also matches one of the patterns in GGLLOOBBIIGGNNOORREE is removed + from the list of matches. If the nnooccaasseegglloobb option is set, the match- + ing against the patterns in GGLLOOBBIIGGNNOORREE is performed without regard to case. The filenames _. and _._. are always ignored when GGLLOOBBIIGGNNOORREE is set - and not null. However, setting GGLLOOBBIIGGNNOORREE to a non-null value has the + and not null. However, setting GGLLOOBBIIGGNNOORREE to a non-null value has the effect of enabling the ddoottgglloobb shell option, so all other filenames be- - ginning with a "." match. To get the old behavior of ignoring file- - names beginning with a ".", make ".*" one of the patterns in GGLLOOBBIIGG-- - NNOORREE. The ddoottgglloobb option is disabled when GGLLOOBBIIGGNNOORREE is unset. The + ginning with a "." match. To get the old behavior of ignoring file- + names beginning with a ".", make ".*" one of the patterns in GGLLOOBBIIGG-- + NNOORREE. The ddoottgglloobb option is disabled when GGLLOOBBIIGGNNOORREE is unset. The GGLLOOBBIIGGNNOORREE pattern matching honors the setting of the eexxttgglloobb shell op- tion. - The value of the GGLLOOBBSSOORRTT shell variable controls how the results of - pathname expansion are sorted, as described above under SShheellll VVaarrii-- + The value of the GGLLOOBBSSOORRTT shell variable controls how the results of + pathname expansion are sorted, as described above under SShheellll VVaarrii-- aabblleess. PPaatttteerrnn MMaattcchhiinngg 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 described below, matches itself. The NUL character may not + occur in a pattern. A backslash escapes the following character; the + escaping backslash is discarded when matching. The special pattern characters must be quoted if they are to be matched literally. The special pattern characters have the following meanings: - ** Matches any string, including the null string. When the - gglloobbssttaarr shell option is enabled, and ** is used in a - pathname expansion context, two adjacent **s used as a - single pattern match all files and zero or more directo- - ries and subdirectories. If followed by a //, two adja- + ** Matches any string, including the null string. When the + gglloobbssttaarr shell option is enabled, and ** is used in a + pathname expansion context, two adjacent **s used as a + single pattern match all files and zero or more directo- + ries and subdirectories. If followed by a //, two adja- cent **s match only directories and subdirectories. ?? Matches any single character. - [[...]] Matches any one of the characters enclosed between the - brackets. This is known as a _b_r_a_c_k_e_t _e_x_p_r_e_s_s_i_o_n and - matches a single character. A pair of characters sepa- + [[...]] Matches any one of the characters enclosed between the + brackets. This is known as a _b_r_a_c_k_e_t _e_x_p_r_e_s_s_i_o_n and + matches a single character. A pair of characters sepa- rated by a hyphen denotes a _r_a_n_g_e _e_x_p_r_e_s_s_i_o_n; any charac- - ter that falls between those two characters, inclusive, + ter that falls between those two characters, inclusive, using the current locale's collating sequence and charac- ter set, matches. If the first character following the [[ - is a !! or a ^^ then any character not within the range - matches. To match a --, include it as the first or last - character in the set. To match a ]], include it as the + is a !! or a ^^ then any character not within the range + matches. To match a --, include it as the first or last + character in the set. To match a ]], include it as the first character in the set. The sorting order of characters in range expressions, and - the characters included in the range, are determined by - the current locale and the values of the LLCC__CCOOLLLLAATTEE or - LLCC__AALLLL shell variables, if set. To obtain the tradi- - tional interpretation of range expressions, where [[aa--dd]] - is equivalent to [[aabbccdd]], set the value of the LLCC__CCOOLLLLAATTEE - or LLCC__AALLLL shell variables to CC, or enable the gglloobbaassccii-- + the characters included in the range, are determined by + the current locale and the values of the LLCC__CCOOLLLLAATTEE or + LLCC__AALLLL shell variables, if set. To obtain the tradi- + tional interpretation of range expressions, where [[aa--dd]] + is equivalent to [[aabbccdd]], set the value of the LLCC__CCOOLLLLAATTEE + or LLCC__AALLLL shell variables to CC, or enable the gglloobbaassccii-- iirraannggeess shell option. - Within a bracket expression, _c_h_a_r_a_c_t_e_r _c_l_a_s_s_e_s can be - specified using the syntax [[::_c_l_a_s_s::]], where _c_l_a_s_s is one + Within a bracket expression, _c_h_a_r_a_c_t_e_r _c_l_a_s_s_e_s can be + specified using the syntax [[::_c_l_a_s_s::]], where _c_l_a_s_s is one of the following classes defined in the POSIX standard: - aallnnuumm aallpphhaa aasscciiii bbllaannkk ccnnttrrll ddiiggiitt ggrraapphh lloowweerr pprriinntt + aallnnuumm aallpphhaa aasscciiii bbllaannkk ccnnttrrll ddiiggiitt ggrraapphh lloowweerr pprriinntt ppuunncctt ssppaaccee uuppppeerr wwoorrdd xxddiiggiitt A character class matches any character belonging to that class. The wwoorrdd character class matches letters, digits, and the character _. - Within a bracket expression, an _e_q_u_i_v_a_l_e_n_c_e _c_l_a_s_s can be + Within a bracket expression, an _e_q_u_i_v_a_l_e_n_c_e _c_l_a_s_s can be specified using the syntax [[==_c==]], which matches all char- - acters with the same collation weight (as defined by the + acters with the same collation weight (as defined by the current locale) as the character _c. - Within a bracket expression, the syntax [[.._s_y_m_b_o_l..]] + Within a bracket expression, the syntax [[.._s_y_m_b_o_l..]] matches the collating symbol _s_y_m_b_o_l. - If the eexxttgglloobb shell option is enabled using the sshhoopptt builtin, the - shell recognizes several extended pattern matching operators. In the + If the eexxttgglloobb shell option is enabled using the sshhoopptt builtin, the + shell recognizes several extended pattern matching operators. In the following description, a _p_a_t_t_e_r_n_-_l_i_s_t is a list of one or more patterns - separated by a ||. Composite patterns may be formed using one or more + separated by a ||. Composite patterns may be formed using one or more of the following sub-patterns: ??((_p_a_t_t_e_r_n_-_l_i_s_t)) @@ -2424,80 +2447,80 @@ EEXXPPAANNSSIIOONN Matches anything except one of the given patterns. The eexxttgglloobb option changes the behavior of the parser, since the paren- - theses are normally treated as operators with syntactic meaning. To - ensure that extended matching patterns are parsed correctly, make sure - that eexxttgglloobb is enabled before parsing constructs containing the pat- + theses are normally treated as operators with syntactic meaning. To + ensure that extended matching patterns are parsed correctly, make sure + that eexxttgglloobb is enabled before parsing constructs containing the pat- terns, including shell functions and command substitutions. When matching filenames, the ddoottgglloobb shell option determines the set of - filenames that are tested: when ddoottgglloobb is enabled, the set of file- - names includes all files beginning with ".", but _. and _._. must be - matched by a pattern or sub-pattern that begins with a dot; when it is + filenames that are tested: when ddoottgglloobb is enabled, the set of file- + names includes all files beginning with ".", but _. and _._. must be + matched by a pattern or sub-pattern that begins with a dot; when it is disabled, the set does not include any filenames beginning with "." un- less the pattern or sub-pattern begins with a ".". If the gglloobbsskkiippddoottss - shell option is enabled, the filenames _. and _._. never appear in the + shell option is enabled, the filenames _. and _._. never appear in the set. As above, "." only has a special meaning when matching filenames. Complicated extended pattern matching against long strings is slow, es- pecially when the patterns contain alternations and the strings contain - multiple matches. Using separate matches against shorter strings, or + multiple matches. Using separate matches against shorter strings, or using arrays of strings instead of a single long string, may be faster. QQuuoottee RReemmoovvaall After the preceding expansions, all unquoted occurrences of the charac- - ters \\, '', and "" that did not result from one of the above expansions + ters \\, '', and "" that did not result from one of the above expansions are removed. RREEDDIIRREECCTTIIOONN - Before a command is executed, its input and output may be _r_e_d_i_r_e_c_t_e_d - using a special notation interpreted by the shell. _R_e_d_i_r_e_c_t_i_o_n allows - commands' file handles to be duplicated, opened, closed, made to refer + Before a command is executed, its input and output may be _r_e_d_i_r_e_c_t_e_d + using a special notation interpreted by the shell. _R_e_d_i_r_e_c_t_i_o_n allows + commands' file handles to be duplicated, opened, closed, made to refer to different files, and can change the files the command reads from and - writes to. When used with the eexxeecc builtin, redirections modify file - handles in the current shell execution environment. The following - redirection operators may precede or appear anywhere within a _s_i_m_p_l_e + writes to. When used with the eexxeecc builtin, redirections modify file + handles in the current shell execution environment. The following + redirection operators may precede or appear anywhere within a _s_i_m_p_l_e _c_o_m_m_a_n_d or may follow a _c_o_m_m_a_n_d. Redirections are processed in the or- der they appear, from left to right. - Each redirection that may be preceded by a file descriptor number may + Each redirection that may be preceded by a file descriptor number may instead be preceded by a word of the form {_v_a_r_n_a_m_e}. In this case, for - each redirection operator except >>&&-- and <<&&--, the shell allocates a - file descriptor greater than or equal to 10 and assigns it to _v_a_r_n_a_m_e. + each redirection operator except >>&&-- and <<&&--, the shell allocates a + file descriptor greater than or equal to 10 and assigns it to _v_a_r_n_a_m_e. If {_v_a_r_n_a_m_e} precedes >>&&-- or <<&&--, the value of _v_a_r_n_a_m_e defines the file - descriptor to close. If {_v_a_r_n_a_m_e} is supplied, the redirection per- - sists beyond the scope of the command, which allows the shell program- + descriptor to close. If {_v_a_r_n_a_m_e} is supplied, the redirection per- + sists beyond the scope of the command, which allows the shell program- mer to manage the file descriptor's lifetime manually without using the eexxeecc builtin. The vvaarrrreeddiirr__cclloossee shell option manages this behavior. - In the following descriptions, if the file descriptor number is omit- - ted, and the first character of the redirection operator is "<", the - redirection refers to the standard input (file descriptor 0). If the - first character of the redirection operator is ">", the redirection + In the following descriptions, if the file descriptor number is omit- + ted, and the first character of the redirection operator is "<", the + redirection refers to the standard input (file descriptor 0). If the + first character of the redirection operator is ">", the redirection refers to the standard output (file descriptor 1). - The _w_o_r_d following the redirection operator in the following descrip- - tions, unless otherwise noted, is subjected to brace expansion, tilde - expansion, parameter and variable expansion, command substitution, - arithmetic expansion, quote removal, pathname expansion, and word + The _w_o_r_d following the redirection operator in the following descrip- + tions, unless otherwise noted, is subjected to brace expansion, tilde + expansion, parameter and variable expansion, command substitution, + arithmetic expansion, quote removal, pathname expansion, and word splitting. If it expands to more than one word, bbaasshh reports an error. The order of redirections is significant. For example, the command ls >> dirlist 2>>&&1 - directs both standard output and standard error to the file _d_i_r_l_i_s_t, + directs both standard output and standard error to the file _d_i_r_l_i_s_t, while the command ls 2>>&&1 >> dirlist - directs only the standard output to file _d_i_r_l_i_s_t, because the standard - error was directed to the standard output before the standard output + directs only the standard output to file _d_i_r_l_i_s_t, because the standard + error was directed to the standard output before the standard output was redirected to _d_i_r_l_i_s_t. BBaasshh handles several filenames specially when they are used in redirec- tions, as described in the following table. If the operating system on - which bbaasshh is running provides these special files, bbaasshh uses them; - otherwise it emulates them internally with the behavior described be- + which bbaasshh is running provides these special files, bbaasshh uses them; + otherwise it emulates them internally with the behavior described be- low. //ddeevv//ffdd//_f_d @@ -2510,22 +2533,22 @@ RREEDDIIRREECCTTIIOONN File descriptor 2 is duplicated. //ddeevv//ttccpp//_h_o_s_t//_p_o_r_t If _h_o_s_t is a valid hostname or Internet address, and _p_o_r_t - is an integer port number or service name, bbaasshh attempts + is an integer port number or service name, bbaasshh attempts to open the corresponding TCP socket. //ddeevv//uuddpp//_h_o_s_t//_p_o_r_t If _h_o_s_t is a valid hostname or Internet address, and _p_o_r_t - is an integer port number or service name, bbaasshh attempts + is an integer port number or service name, bbaasshh attempts to open the corresponding UDP socket. A failure to open or create a file causes the redirection to fail. - Redirections using file descriptors greater than 9 should be used with - care, as they may conflict with file descriptors the shell uses inter- + Redirections using file descriptors greater than 9 should be used with + care, as they may conflict with file descriptors the shell uses inter- nally. RReeddiirreeccttiinngg IInnppuutt - Redirecting input opens the file whose name results from the expansion - of _w_o_r_d for reading on file descriptor _n, or the standard input (file + Redirecting input opens the file whose name results from the expansion + of _w_o_r_d for reading on file descriptor _n, or the standard input (file descriptor 0) if _n is not specified. The general format for redirecting input is: @@ -2534,24 +2557,24 @@ RREEDDIIRREECCTTIIOONN RReeddiirreeccttiinngg OOuuttppuutt Redirecting output opens the file whose name results from the expansion - of _w_o_r_d for writing on file descriptor _n, or the standard output (file - descriptor 1) if _n is not specified. If the file does not exist it is + of _w_o_r_d for writing on file descriptor _n, or the standard output (file + descriptor 1) if _n is not specified. If the file does not exist it is created; if it does exist it is truncated to zero size. The general format for redirecting output is: [_n]>>_w_o_r_d - If the redirection operator is >>, and the nnoocclloobbbbeerr option to the sseett - builtin command has been enabled, the redirection fails if the file - whose name results from the expansion of _w_o_r_d exists and is a regular - file. If the redirection operator is >>||, or the redirection operator - is >> and the nnoocclloobbbbeerr option to the sseett builtin is not enabled, bbaasshh + If the redirection operator is >>, and the nnoocclloobbbbeerr option to the sseett + builtin command has been enabled, the redirection fails if the file + whose name results from the expansion of _w_o_r_d exists and is a regular + file. If the redirection operator is >>||, or the redirection operator + is >> and the nnoocclloobbbbeerr option to the sseett builtin is not enabled, bbaasshh attempts the redirection even if the file named by _w_o_r_d exists. AAppppeennddiinngg RReeddiirreecctteedd OOuuttppuutt - Redirecting output in this fashion opens the file whose name results - from the expansion of _w_o_r_d for appending on file descriptor _n, or the + Redirecting output in this fashion opens the file whose name results + from the expansion of _w_o_r_d for appending on file descriptor _n, or the standard output (file descriptor 1) if _n is not specified. If the file does not exist it is created. @@ -2560,11 +2583,11 @@ RREEDDIIRREECCTTIIOONN [_n]>>>>_w_o_r_d RReeddiirreeccttiinngg SSttaannddaarrdd OOuuttppuutt aanndd SSttaannddaarrdd EErrrroorr - This construct redirects both the standard output (file descriptor 1) - and the standard error output (file descriptor 2) to the file whose + This construct redirects both the standard output (file descriptor 1) + and the standard error output (file descriptor 2) to the file whose name is the expansion of _w_o_r_d. - There are two formats for redirecting standard output and standard er- + There are two formats for redirecting standard output and standard er- ror: &&>>_w_o_r_d @@ -2576,8 +2599,8 @@ RREEDDIIRREECCTTIIOONN >>_w_o_r_d 2>>&&1 - When using the second form, _w_o_r_d may not expand to a number or --. If - it does, other redirection operators apply (see DDuupplliiccaattiinngg FFiillee DDee-- + When using the second form, _w_o_r_d may not expand to a number or --. If + it does, other redirection operators apply (see DDuupplliiccaattiinngg FFiillee DDee-- ssccrriippttoorrss below) for compatibility reasons. AAppppeennddiinngg SSttaannddaarrdd OOuuttppuutt aanndd SSttaannddaarrdd EErrrroorr @@ -2596,10 +2619,10 @@ RREEDDIIRREECCTTIIOONN (see DDuupplliiccaattiinngg FFiillee DDeessccrriippttoorrss below). HHeerree DDooccuummeennttss - This type of redirection instructs the shell to read input from the + This type of redirection instructs the shell to read input from the current source until it reads a line containing only _d_e_l_i_m_i_t_e_r (with no - trailing blanks). All of the lines read up to that point then become - the standard input (or file descriptor _n if _n is specified) for a com- + trailing blanks). All of the lines read up to that point then become + the standard input (or file descriptor _n if _n is specified) for a com- mand. The format of here-documents is: @@ -2608,37 +2631,37 @@ RREEDDIIRREECCTTIIOONN _h_e_r_e_-_d_o_c_u_m_e_n_t _d_e_l_i_m_i_t_e_r - The shell does not perform parameter and variable expansion, command + The shell does not perform parameter and variable expansion, command substitution, arithmetic expansion, or pathname expansion on _w_o_r_d. If any part of _w_o_r_d is quoted, the _d_e_l_i_m_i_t_e_r is the result of quote re- moval on _w_o_r_d, and the lines in the here-document are not expanded. If - _w_o_r_d is unquoted, the _d_e_l_i_m_i_t_e_r is _w_o_r_d itself, and the here-document - text is treated similarly to a double-quoted string: all lines of the - here-document are subjected to parameter expansion, command substitu- - tion, and arithmetic expansion, the character sequence \\<> is + _w_o_r_d is unquoted, the _d_e_l_i_m_i_t_e_r is _w_o_r_d itself, and the here-document + text is treated similarly to a double-quoted string: all lines of the + here-document are subjected to parameter expansion, command substitu- + tion, and arithmetic expansion, the character sequence \\<> is treated literally, and \\ must be used to quote the characters \\, $$, and ``; however, double quote characters have no special meaning. - If the redirection operator is <<<<--, then the shell strips all leading - tab characters from input lines and the line containing _d_e_l_i_m_i_t_e_r. - This allows here-documents within shell scripts to be indented in a + If the redirection operator is <<<<--, then the shell strips all leading + tab characters from input lines and the line containing _d_e_l_i_m_i_t_e_r. + This allows here-documents within shell scripts to be indented in a natural fashion. - If the delimiter is not quoted, the \\<> sequence is treated as a - line continuation: the two lines are joined and the backslash-newline - is removed. This happens while reading the here-document, before the - check for the ending delimiter, so joined lines can form the end delim- - iter. + If the delimiter is not quoted, the shell treats the \\<> se- + quence as a line continuation: the two lines are joined and the back- + slash-newline is removed. This happens while reading the here-docu- + ment, before the check for the ending delimiter, so joined lines can + form the end delimiter. HHeerree SSttrriinnggss A variant of here documents, the format is: [_n]<<<<<<_w_o_r_d - The _w_o_r_d undergoes tilde expansion, parameter and variable expansion, - command substitution, arithmetic expansion, and quote removal. Path- - name expansion and word splitting are not performed. The result is + The _w_o_r_d undergoes tilde expansion, parameter and variable expansion, + command substitution, arithmetic expansion, and quote removal. Path- + name expansion and word splitting are not performed. The result is supplied as a single string, with a newline appended, to the command on its standard input (or file descriptor _n if _n is specified). @@ -2648,22 +2671,22 @@ RREEDDIIRREECCTTIIOONN [_n]<<&&_w_o_r_d is used to duplicate input file descriptors. If _w_o_r_d expands to one or - more digits, file descriptor _n is made to be a copy of that file de- + more digits, file descriptor _n is made to be a copy of that file de- scriptor. It is a redirection error if the digits in _w_o_r_d do not spec- ify a file descriptor open for input. If _w_o_r_d evaluates to --, file de- - scriptor _n is closed. If _n is not specified, this uses the standard + scriptor _n is closed. If _n is not specified, this uses the standard input (file descriptor 0). The operator [_n]>>&&_w_o_r_d - is used similarly to duplicate output file descriptors. If _n is not - specified, this uses the standard output (file descriptor 1). It is a - redirection error if the digits in _w_o_r_d do not specify a file descrip- - tor open for output. If _w_o_r_d evaluates to --, file descriptor _n is - closed. As a special case, if _n is omitted, and _w_o_r_d does not expand - to one or more digits or --, this redirects the standard output and + is used similarly to duplicate output file descriptors. If _n is not + specified, this uses the standard output (file descriptor 1). It is a + redirection error if the digits in _w_o_r_d do not specify a file descrip- + tor open for output. If _w_o_r_d evaluates to --, file descriptor _n is + closed. As a special case, if _n is omitted, and _w_o_r_d does not expand + to one or more digits or --, this redirects the standard output and standard error as described previously. MMoovviinngg FFiillee DDeessccrriippttoorrss @@ -2671,7 +2694,7 @@ RREEDDIIRREECCTTIIOONN [_n]<<&&_d_i_g_i_t-- - moves the file descriptor _d_i_g_i_t to file descriptor _n, or the standard + moves the file descriptor _d_i_g_i_t to file descriptor _n, or the standard input (file descriptor 0) if _n is not specified. _d_i_g_i_t is closed after being duplicated to _n. @@ -2679,7 +2702,7 @@ RREEDDIIRREECCTTIIOONN [_n]>>&&_d_i_g_i_t-- - moves the file descriptor _d_i_g_i_t to file descriptor _n, or the standard + moves the file descriptor _d_i_g_i_t to file descriptor _n, or the standard output (file descriptor 1) if _n is not specified. OOppeenniinngg FFiillee DDeessccrriippttoorrss ffoorr RReeaaddiinngg aanndd WWrriittiinngg @@ -2692,170 +2715,170 @@ RREEDDIIRREECCTTIIOONN ified. If the file does not exist, it is created. AALLIIAASSEESS - _A_l_i_a_s_e_s allow a string to be substituted for a word that is in a posi- - tion in the input where it can be the first word of a simple command. - Aliases have names and corresponding values that are set and unset us- - ing the aalliiaass and uunnaalliiaass builtin commands (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS + _A_l_i_a_s_e_s allow a string to be substituted for a word that is in a posi- + tion in the input where it can be the first word of a simple command. + Aliases have names and corresponding values that are set and unset us- + ing the aalliiaass and uunnaalliiaass builtin commands (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). - If the shell reads an unquoted word in the right position, it checks - the word to see if it matches an alias name. If it matches, the shell - replaces the word with the alias value, and reads that value as if it + If the shell reads an unquoted word in the right position, it checks + the word to see if it matches an alias name. If it matches, the shell + replaces the word with the alias value, and reads that value as if it had been read instead of the word. The shell doesn't look at any char- acters following the word before attempting alias substitution. - The characters //, $$, ``, and == and any of the shell _m_e_t_a_c_h_a_r_a_c_t_e_r_s 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 + The characters //, $$, ``, and == and any of the shell _m_e_t_a_c_h_a_r_a_c_t_e_r_s 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 llss to llss --FF, for - instance, and bbaasshh does not try to recursively expand the replacement + instance, and bbaasshh does not try to recursively expand the replacement text. - If the last character of the alias value is a _b_l_a_n_k, the shell checks + If the last character of the alias value is a _b_l_a_n_k, the shell checks the next command word following the alias for alias expansion. Aliases are created and listed with the aalliiaass command, and removed with the uunnaalliiaass command. - There is no mechanism for using arguments in the replacement text. If - arguments are needed, use a shell function (see FFUUNNCCTTIIOONNSS below) in- + There is no mechanism for using arguments in the replacement text. If + arguments are needed, use a shell function (see FFUUNNCCTTIIOONNSS below) in- stead. - Aliases are not expanded when the shell is not interactive, unless the - eexxppaanndd__aalliiaasseess shell option is set using sshhoopptt (see the description of + Aliases are not expanded when the shell is not interactive, unless the + eexxppaanndd__aalliiaasseess shell option is set using sshhoopptt (see the description of sshhoopptt under SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). - The rules concerning the definition and use of aliases are somewhat - confusing. BBaasshh always reads at least one complete line of input, and - all lines that make up a compound command, before executing any of the - commands on that line or the compound command. 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 + The rules concerning the definition and use of aliases are somewhat + confusing. BBaasshh always reads at least one complete line of input, and + all lines that make up a compound command, before executing any of the + commands on that line or the compound command. 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 shell reads the next line of input, and an alias defi- - nition in a compound command does not take effect until the shell - parses and executes the entire compound command. The commands follow- - ing the alias definition on that line, or in the rest of a compound - command, are not affected by the new alias. This behavior is also an - issue when functions are executed. Aliases are expanded when a func- - tion definition is read, not when the function is executed, because a + nition in a compound command does not take effect until the shell + parses and executes the entire compound command. The commands follow- + ing the alias definition on that line, or in the rest of a compound + command, are not affected by the new alias. This behavior is also an + issue when functions are executed. Aliases are expanded when a func- + tion definition is read, not when the function is executed, because a function definition is itself a command. As a consequence, aliases de- fined in a function are not available until after that function is exe- - cuted. To be safe, always put alias definitions on a separate line, + cuted. To be safe, always put alias definitions on a separate line, and do not use aalliiaass in compound commands. For almost every purpose, shell functions are preferable to aliases. FFUUNNCCTTIIOONNSS - A shell function, defined as described above under SSHHEELLLL GGRRAAMMMMAARR, - stores a series of commands for later execution. When the name of a + A shell function, defined as described above under SSHHEELLLL GGRRAAMMMMAARR, + stores a series of commands for later execution. When the name of a shell function is used as a simple command name, the shell executes the list of commands associated with that function name. Functions are ex- - ecuted in the context of the calling shell; there is no new process - created to interpret them (contrast this with the execution of a shell + ecuted in the context of the calling shell; there is no new process + 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 + When a function is executed, the arguments to the function become the positional parameters during its execution. The special parameter ## is - updated to reflect the new positional parameters. Special parameter 00 + updated to reflect the new positional parameters. Special parameter 00 is unchanged. The first element of the FFUUNNCCNNAAMMEE variable is set to the name of the function while the function is executing. - All other aspects of the shell execution environment are identical be- - tween a function and its caller with these exceptions: the DDEEBBUUGG and - RREETTUURRNN traps (see the description of the ttrraapp builtin under SSHHEELLLL - BBUUIILLTTIINN CCOOMMMMAANNDDSS below) are not inherited unless the function has been - given the ttrraaccee attribute (see the description of the ddeeccllaarree builtin - below) or the --oo ffuunnccttrraaccee shell option has been enabled with the sseett - builtin (in which case all functions inherit the DDEEBBUUGG and RREETTUURRNN - traps), and the EERRRR trap is not inherited unless the --oo eerrrrttrraaccee shell + All other aspects of the shell execution environment are identical be- + tween a function and its caller with these exceptions: the DDEEBBUUGG and + RREETTUURRNN traps (see the description of the ttrraapp builtin under SSHHEELLLL + BBUUIILLTTIINN CCOOMMMMAANNDDSS below) are not inherited unless the function has been + given the ttrraaccee attribute (see the description of the ddeeccllaarree builtin + below) or the --oo ffuunnccttrraaccee shell option has been enabled with the sseett + builtin (in which case all functions inherit the DDEEBBUUGG and RREETTUURRNN + traps), and the EERRRR trap is not inherited unless the --oo eerrrrttrraaccee shell option has been enabled. - Variables local to the function are declared with the llooccaall builtin - command (_l_o_c_a_l _v_a_r_i_a_b_l_e_s). Ordinarily, variables and their values are - shared between the function and its caller. If a variable is declared - llooccaall, the variable's visible scope is restricted to that function and + Variables local to the function are declared with the llooccaall builtin + command (_l_o_c_a_l _v_a_r_i_a_b_l_e_s). Ordinarily, variables and their values are + shared between the function and its caller. If a variable is declared + llooccaall, the variable's visible scope is restricted to that function and its children (including the functions it calls). In the following description, the _c_u_r_r_e_n_t _s_c_o_p_e is a currently- execut- ing function. Previous scopes consist of that function's caller and so - on, back to the "global" scope, where the shell is not executing any - shell function. A local variable at the current scope is a variable - declared using the llooccaall or ddeeccllaarree builtins in the function that is + on, back to the "global" scope, where the shell is not executing any + shell function. A local variable at the current scope is a variable + declared using the llooccaall or ddeeccllaarree builtins in the function that is currently executing. - Local variables "shadow" variables with the same name declared at pre- - vious scopes. For instance, a local variable declared in a function + Local variables "shadow" variables with the same name declared at pre- + vious scopes. For instance, a local variable declared in a function hides variables with the same name declared at previous scopes, includ- - ing global variables: references and assignments refer to the local - variable, leaving the variables at previous scopes unmodified. When + ing global variables: references and assignments refer to the local + variable, leaving the variables at previous scopes unmodified. When the function returns, the global variable is once again visible. - The shell uses _d_y_n_a_m_i_c _s_c_o_p_i_n_g to control a variable's visibility - within functions. With dynamic scoping, visible variables and their - values are a result of the sequence of function calls that caused exe- - cution to reach the current function. The value of a variable that a - function sees depends on its value within its caller, if any, whether - that caller is the global scope or another shell function. This is + The shell uses _d_y_n_a_m_i_c _s_c_o_p_i_n_g to control a variable's visibility + within functions. With dynamic scoping, visible variables and their + values are a result of the sequence of function calls that caused exe- + cution to reach the current function. The value of a variable that a + function sees depends on its value within its caller, if any, whether + that caller is the global scope or another shell function. This is also the value that a local variable declaration shadows, and the value that is restored when the function returns. - For example, if a variable _v_a_r is declared as local in function _f_u_n_c_1, - and _f_u_n_c_1 calls another function _f_u_n_c_2, references to _v_a_r made from - within _f_u_n_c_2 resolve to the local variable _v_a_r from _f_u_n_c_1, shadowing + For example, if a variable _v_a_r is declared as local in function _f_u_n_c_1, + and _f_u_n_c_1 calls another function _f_u_n_c_2, references to _v_a_r made from + within _f_u_n_c_2 resolve to the local variable _v_a_r from _f_u_n_c_1, shadowing any global variable named _v_a_r. The uunnsseett builtin also acts using the same dynamic scope: if a variable - is local to the current scope, uunnsseett unsets it; otherwise the unset - will refer to the variable found in any calling scope as described - above. If a variable at the current local scope is unset, it remains - so (appearing as unset) until it is reset in that scope or until the + is local to the current scope, uunnsseett unsets it; otherwise the unset + will refer to the variable found in any calling scope as described + above. If a variable at the current local scope is unset, it remains + so (appearing as unset) until it is reset in that scope or until the function returns. Once the function returns, any instance of the vari- able at a previous scope becomes visible. If the unset acts on a vari- - able at a previous scope, any instance of a variable with that name - that had been shadowed becomes visible (see below how the llooccaallvvaarr__uunn-- + able at a previous scope, any instance of a variable with that name + that had been shadowed becomes visible (see below how the llooccaallvvaarr__uunn-- sseett shell option changes this behavior). - The FFUUNNCCNNEESSTT variable, if set to a numeric value greater than 0, de- - fines a maximum function nesting level. Function invocations that ex- + The FFUUNNCCNNEESSTT variable, if set to a numeric value greater than 0, de- + fines a maximum function nesting level. Function invocations that ex- ceed the limit cause the entire command to abort. - If the builtin command rreettuurrnn is executed in a function, the function - completes and execution resumes with the next command after the func- + If the builtin command rreettuurrnn is executed in a function, the function + completes and execution resumes with the next command after the func- tion call. If rreettuurrnn is supplied a numeric argument, that is the func- - tion's return status; otherwise the function's return status is the - exit status of the last command executed before the rreettuurrnn. Any com- - mand associated with the RREETTUURRNN trap is executed before execution re- + tion's return status; otherwise the function's return status is the + exit status of the last command executed before the rreettuurrnn. Any com- + mand associated with the RREETTUURRNN trap is executed before execution re- sumes. When a function completes, the values of the positional parame- - ters and the special parameter ## are restored to the values they had + ters and the special parameter ## are restored to the values they had prior to the function's execution. The --ff option to the ddeeccllaarree or ttyyppeesseett builtin commands lists function - names and definitions. The --FF option to ddeeccllaarree or ttyyppeesseett lists the + names and definitions. The --FF option to ddeeccllaarree or ttyyppeesseett lists the function names only (and optionally the source file and line number, if - the eexxttddeebbuugg shell option is enabled). Functions may be exported so - that child shell processes (those created when executing a separate + the eexxttddeebbuugg shell option is enabled). Functions may be exported so + that child shell processes (those created when executing a separate shell invocation) automatically have them defined with the --ff option to the eexxppoorrtt builtin. The --ff option to the uunnsseett builtin deletes a func- tion definition. Functions may be recursive. The FFUUNNCCNNEESSTT variable may be used to limit - the depth of the function call stack and restrict the number of func- - tion invocations. By default, bbaasshh imposes no limit on the number of + the depth of the function call stack and restrict the number of func- + tion invocations. By default, bbaasshh imposes no limit on the number of recursive calls. AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN - The shell allows arithmetic expressions to be evaluated, under certain - circumstances (see the lleett and ddeeccllaarree builtin commands, the (((( com- - pound command, the arithmetic ffoorr command, the [[[[ conditional command, + The shell allows arithmetic expressions to be evaluated, under certain + circumstances (see the lleett and ddeeccllaarree builtin commands, the (((( com- + pound command, the arithmetic ffoorr command, the [[[[ conditional command, and AArriitthhmmeettiicc EExxppaannssiioonn). - Evaluation is done in the largest fixed-width integers available, with - no check for overflow, though division by 0 is trapped and flagged as - an error. The operators and their precedence, associativity, and val- + Evaluation is done in the largest fixed-width integers available, with + no check for overflow, though division by 0 is trapped and flagged as + an error. The operators and their precedence, associativity, and val- ues are the same as in the C language. The following list of operators - is grouped into levels of equal-precedence operators. The levels are + is grouped into levels of equal-precedence operators. The levels are listed in order of decreasing precedence. _i_d++++ _i_d---- @@ -2883,63 +2906,63 @@ AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN _e_x_p_r_1 ,, _e_x_p_r_2 comma - Shell variables are allowed as operands; parameter expansion is per- + Shell variables are allowed as operands; parameter expansion is per- formed before the expression is evaluated. Within an expression, shell - variables may also be referenced by name without using the parameter + variables may also be referenced by name without using the parameter expansion syntax. This means you can use "x", where _x is a shell vari- able name, in an arithmetic expression, and the shell will evaluate its - value as an expression and use the result. A shell variable that is + value as an expression and use the result. A shell variable that is null or unset evaluates to 0 when referenced by name in an expression. - The value of a variable is evaluated as an arithmetic expression when - it is referenced, or when a variable which has been given the _i_n_t_e_g_e_r + The value of a variable is evaluated as an arithmetic expression when + it is referenced, or when a variable which has been given the _i_n_t_e_g_e_r attribute using ddeeccllaarree --ii is assigned a value. A null value evaluates - to 0. A shell variable need not have its _i_n_t_e_g_e_r attribute enabled to + to 0. A shell variable need not have its _i_n_t_e_g_e_r attribute enabled to be used in an expression. Integer constants follow the C language definition, without suffixes or character constants. Constants with a leading 0 are interpreted as oc- - tal numbers. A leading 0x or 0X denotes hexadecimal. Otherwise, num- - bers take the form [_b_a_s_e_#]n, where the optional _b_a_s_e is a decimal num- - ber between 2 and 64 representing the arithmetic base, and _n is a num- - ber in that base. If _b_a_s_e_# is omitted, then base 10 is used. When + tal numbers. A leading 0x or 0X denotes hexadecimal. Otherwise, num- + bers take the form [_b_a_s_e_#]n, where the optional _b_a_s_e is a decimal num- + ber between 2 and 64 representing the arithmetic base, and _n is a num- + ber in that base. If _b_a_s_e_# is omitted, then base 10 is used. When specifying _n, if a non-digit is required, the digits greater than 9 are - represented by the lowercase letters, the uppercase letters, @, and _, - in that order. If _b_a_s_e is less than or equal to 36, lowercase and up- - percase letters may be used interchangeably to represent numbers be- + represented by the lowercase letters, the uppercase letters, @, and _, + in that order. If _b_a_s_e is less than or equal to 36, lowercase and up- + percase letters may be used interchangeably to represent numbers be- tween 10 and 35. Operators are evaluated in precedence order. Sub-expressions in paren- theses are evaluated first and may override the precedence rules above. CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS - Conditional expressions are used by the [[[[ compound command and the - tteesstt and [[ builtin commands to test file attributes and perform string - and arithmetic comparisons. The tteesstt and [[ commands determine their - behavior based on the number of arguments; see the descriptions of + Conditional expressions are used by the [[[[ compound command and the + tteesstt and [[ builtin commands to test file attributes and perform string + and arithmetic comparisons. The tteesstt and [[ commands determine their + behavior based on the number of arguments; see the descriptions of those commands for any other command-specific actions. Expressions are formed from the unary or binary primaries listed below. - Unary expressions are often used to examine the status of a file or - shell variable. Binary operators are used for string, numeric, and + Unary expressions are often used to examine the status of a file or + shell variable. Binary operators are used for string, numeric, and file attribute comparisons. - BBaasshh handles several filenames specially when they are used in expres- + BBaasshh handles several filenames specially when they are used in expres- sions. If the operating system on which bbaasshh is running provides these - special files, bash will use them; otherwise it will emulate them in- - ternally with this behavior: If any _f_i_l_e argument to one of the pri- - maries is of the form _/_d_e_v_/_f_d_/_n, then bbaasshh checks file descriptor _n. - If the _f_i_l_e argument to one of the primaries is one of _/_d_e_v_/_s_t_d_i_n, - _/_d_e_v_/_s_t_d_o_u_t, or _/_d_e_v_/_s_t_d_e_r_r, bbaasshh checks file descriptor 0, 1, or 2, + special files, bash will use them; otherwise it will emulate them in- + ternally with this behavior: If any _f_i_l_e argument to one of the pri- + maries is of the form _/_d_e_v_/_f_d_/_n, then bbaasshh checks file descriptor _n. + If the _f_i_l_e argument to one of the primaries is one of _/_d_e_v_/_s_t_d_i_n, + _/_d_e_v_/_s_t_d_o_u_t, or _/_d_e_v_/_s_t_d_e_r_r, bbaasshh checks file descriptor 0, 1, or 2, respectively. Unless otherwise specified, primaries that operate on files follow sym- bolic links and operate on the target of the link, rather than the link itself. - When used with [[[[, or when the shell is in posix mode, the << and >> op- - erators sort lexicographically using the current locale. When the - shell is not in posix mode, the tteesstt command sorts using ASCII order- + When used with [[[[, or when the shell is in posix mode, the << and >> op- + erators sort lexicographically using the current locale. When the + shell is not in posix mode, the tteesstt command sorts using ASCII order- ing. --aa _f_i_l_e @@ -2978,25 +3001,25 @@ CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS --LL _f_i_l_e True if _f_i_l_e exists and is a symbolic link. --NN _f_i_l_e - True if _f_i_l_e exists and has been modified since it was last ac- + True if _f_i_l_e exists and has been modified since it was last ac- cessed. --OO _f_i_l_e True if _f_i_l_e exists and is owned by the effective user id. --SS _f_i_l_e True if _f_i_l_e exists and is a socket. --oo _o_p_t_n_a_m_e - True if the shell option _o_p_t_n_a_m_e is enabled. See the list of - options under the description of the --oo option to the sseett + True if the shell option _o_p_t_n_a_m_e is enabled. See the list of + options under the description of the --oo option to the sseett builtin below. --vv _v_a_r_n_a_m_e - True if the shell variable _v_a_r_n_a_m_e is set (has been assigned a - value). If _v_a_r_n_a_m_e is an indexed array variable name sub- - scripted by _@ or _*, this returns true if the array has any set + True if the shell variable _v_a_r_n_a_m_e is set (has been assigned a + value). If _v_a_r_n_a_m_e is an indexed array variable name sub- + scripted by _@ or _*, this returns true if the array has any set elements. If _v_a_r_n_a_m_e is an associative array variable name sub- - scripted by _@ or _*, this returns true if an element with that + scripted by _@ or _*, this returns true if an element with that key is set. --RR _v_a_r_n_a_m_e - True if the shell variable _v_a_r_n_a_m_e is set and is a name refer- + True if the shell variable _v_a_r_n_a_m_e is set and is a name refer- ence. --zz _s_t_r_i_n_g True if the length of _s_t_r_i_n_g is zero. @@ -3006,8 +3029,8 @@ CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS _s_t_r_i_n_g_1 ==== _s_t_r_i_n_g_2 _s_t_r_i_n_g_1 == _s_t_r_i_n_g_2 - True if the strings are equal. == should be used with the tteesstt - command for POSIX conformance. When used with the [[[[ command, + True if the strings are equal. == should be used with the tteesstt + command for POSIX conformance. When used with the [[[[ command, this performs pattern matching as described above (CCoommppoouunndd CCoomm-- mmaannddss). _s_t_r_i_n_g_1 !!== _s_t_r_i_n_g_2 @@ -3018,127 +3041,127 @@ CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS True if _s_t_r_i_n_g_1 sorts after _s_t_r_i_n_g_2 lexicographically. _f_i_l_e_1 --eeff _f_i_l_e_2 - True if _f_i_l_e_1 and _f_i_l_e_2 refer to the same device and inode num- + True if _f_i_l_e_1 and _f_i_l_e_2 refer to the same device and inode num- bers. _f_i_l_e_1 -nntt _f_i_l_e_2 - True if _f_i_l_e_1 is newer (according to modification date) than + True if _f_i_l_e_1 is newer (according to modification date) than _f_i_l_e_2, or if _f_i_l_e_1 exists and _f_i_l_e_2 does not. _f_i_l_e_1 -oott _f_i_l_e_2 - True if _f_i_l_e_1 is older than _f_i_l_e_2, or if _f_i_l_e_2 exists and _f_i_l_e_1 + True if _f_i_l_e_1 is older than _f_i_l_e_2, or if _f_i_l_e_2 exists and _f_i_l_e_1 does not. _a_r_g_1 OOPP _a_r_g_2 - OOPP is one of --eeqq, --nnee, --lltt, --llee, --ggtt, or --ggee. These arithmetic - binary operators return true if _a_r_g_1 is equal to, not equal to, - less than, less than or equal to, greater than, or greater than - or equal to _a_r_g_2, respectively. _a_r_g_1 and _a_r_g_2 may be positive - or negative integers. When used with the [[[[ command, _a_r_g_1 and - _a_r_g_2 are evaluated as arithmetic expressions (see AARRIITTHHMMEETTIICC + OOPP is one of --eeqq, --nnee, --lltt, --llee, --ggtt, or --ggee. These arithmetic + binary operators return true if _a_r_g_1 is equal to, not equal to, + less than, less than or equal to, greater than, or greater than + or equal to _a_r_g_2, respectively. _a_r_g_1 and _a_r_g_2 may be positive + or negative integers. When used with the [[[[ command, _a_r_g_1 and + _a_r_g_2 are evaluated as arithmetic expressions (see AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN above). Since the expansions the [[[[ command performs on _a_r_g_1 and _a_r_g_2 can potentially result in empty strings, arith- - metic expression evaluation treats those as expressions that + metic expression evaluation treats those as expressions that evaluate to 0. SSIIMMPPLLEE CCOOMMMMAANNDD EEXXPPAANNSSIIOONN When the shell executes a simple command, it performs the following ex- - pansions, assignments, and redirections, from left to right, in the + pansions, assignments, and redirections, from left to right, in the following order. - 1. The words that the parser has marked as variable assignments - (those preceding the command name) and redirections are saved + 1. The words that the parser has marked as variable assignments + (those preceding the command name) and redirections are saved for later processing. - 2. The words that are not variable assignments or redirections are - expanded. If any words remain after expansion, the first word - is taken to be the name of the command and the remaining words + 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. 3. Redirections are performed as described above under RREEDDIIRREECCTTIIOONN. 4. The text after the == in each variable assignment undergoes tilde expansion, parameter expansion, command substitution, arithmetic - expansion, and quote removal before being assigned to the vari- + expansion, and quote removal before being assigned to the vari- able. If no command name results, the variable assignments affect the current - shell environment. In the case of such a command (one that consists - only of assignment statements and redirections), assignment statements - are performed before redirections. Otherwise, the variables are added - to the environment of the executed command and do not affect the cur- + shell environment. In the case of such a command (one that consists + only of assignment statements and redirections), assignment statements + are performed before redirections. Otherwise, the variables are added + to the environment of the executed command and do not affect the cur- rent shell environment. If any of the assignments attempts to assign a - value to a readonly variable, an error occurs, and the command exits + 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 af- - fect the current shell environment. A redirection error causes the + If no command name results, redirections are performed, but do not af- + fect 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 expan- - sions contained a command substitution, the exit status of the command - is the exit status of the last command substitution performed. If + If there is a command name left after expansion, execution proceeds as + described below. Otherwise, the command exits. If one of the expan- + sions 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 zero sta- tus. CCOOMMMMAANNDD EEXXEECCUUTTIIOONN - After a command has been split into words, if it results in a simple - command and an optional list of arguments, the shell performs the fol- + After a command has been split into words, if it results in a simple + command and an optional list of arguments, the shell performs the fol- lowing actions. - 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 FFUUNNCCTTIIOONNSS. If the name does not match a - function, the shell searches for it in the list of shell builtins. If + 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 FFUUNNCCTTIIOONNSS. 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. - If the name is neither a shell function nor a builtin, and contains no - slashes, bbaasshh searches each element of the PPAATTHH for a directory con- + If the name is neither a shell function nor a builtin, and contains no + slashes, bbaasshh searches each element of the PPAATTHH for a directory con- taining an executable file by that name. BBaasshh uses a hash table to re- - member the full pathnames of executable files (see hhaasshh under SSHHEELLLL - BBUUIILLTTIINN CCOOMMMMAANNDDSS below). Bash performs a full search of the directo- - ries in PPAATTHH 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 ccoommmmaanndd__nnoott__ffoouunndd__hhaannddllee. If that function exists, it - is invoked in a separate execution environment with the original com- - mand and the original command's arguments as its arguments, and the - function's exit status becomes the exit status of that subshell. If + member the full pathnames of executable files (see hhaasshh under SSHHEELLLL + BBUUIILLTTIINN CCOOMMMMAANNDDSS below). Bash performs a full search of the directo- + ries in PPAATTHH 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 ccoommmmaanndd__nnoott__ffoouunndd__hhaannddllee. If that function exists, it + is invoked in a separate execution environment with the original com- + mand and the original command's arguments as its arguments, and the + function's exit status becomes the exit status of that subshell. If that function is not defined, the shell prints an error message and re- turns an exit status of 127. - If the search is successful, or if the command name contains one or + If the search is successful, or if the command name contains one or more slashes, the shell executes the named program in a separate execu- tion environment. Argument 0 is set to the name given, and the remain- ing arguments to the command are set to the arguments given, if any. - 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 _s_h_e_l_l _s_c_r_i_p_t, a + 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 _s_h_e_l_l _s_c_r_i_p_t, a file containing shell commands, and the shell creates a new instance of - itself to execute it. Bash tries to determine whether the file is a - text file or a binary, and will not execute files it determines to be + itself to execute it. Bash tries to determine whether the file is a + text file or a binary, and will not execute files it determines to be binaries. This subshell reinitializes itself, so that the effect is as - if a new shell had been invoked to handle the script, with the excep- - tion that the locations of commands remembered by the parent (see hhaasshh + if a new shell had been invoked to handle the script, with the excep- + tion that the locations of commands remembered by the parent (see hhaasshh below under SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS are retained by the child. - If the program is a file beginning with ##!!, the remainder of the first - line specifies an interpreter for the program. The shell executes the + If the program is a file beginning with ##!!, 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 exe- cutable 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 + 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. CCOOMMMMAANNDD EEXXEECCUUTTIIOONN EENNVVIIRROONNMMEENNTT - The shell has an _e_x_e_c_u_t_i_o_n _e_n_v_i_r_o_n_m_e_n_t, which consists of the follow- + The shell has an _e_x_e_c_u_t_i_o_n _e_n_v_i_r_o_n_m_e_n_t, which consists of the follow- ing: - +o Open files inherited by the shell at invocation, as modified by + +o Open files inherited by the shell at invocation, as modified by redirections supplied to the eexxeecc builtin. - +o The current working directory as set by ccdd, ppuusshhdd, or ppooppdd, or + +o The current working directory as set by ccdd, ppuusshhdd, or ppooppdd, or inherited by the shell at invocation. - +o The file creation mode mask as set by uummaasskk or inherited from + +o The file creation mode mask as set by uummaasskk or inherited from the shell's parent. +o Current traps set by ttrraapp. @@ -3146,135 +3169,135 @@ CCOOMMMMAANNDD EEXXEECCUUTTIIOONN EENNVVIIRROONNMMEENN +o Shell parameters that are set by variable assignment or with sseett or inherited from the shell's parent in the environment. - +o Shell functions defined during execution or inherited from the + +o Shell functions defined during execution or inherited from the shell's parent in the environment. - +o Options enabled at invocation (either by default or with com- + +o Options enabled at invocation (either by default or with com- mand-line arguments) or by sseett. +o Options enabled by sshhoopptt. +o Shell aliases defined with aalliiaass. - +o Various process IDs, including those of background jobs, the + +o Various process IDs, including those of background jobs, the value of $$$$, and the value of PPPPIIDD. - When a simple command other than a builtin or shell function is to be - executed, it is invoked in a separate execution environment that con- - sists of the following. Unless otherwise noted, the values are inher- + When a simple command other than a builtin or shell function is to be + executed, it is invoked in a separate execution environment that con- + sists of the following. Unless otherwise noted, the values are inher- ited from the shell. - +o The shell's open files, plus any modifications and additions + +o The shell's open files, plus any modifications and additions specified by redirections to the command. +o The current working directory. +o The file creation mode mask. - +o Shell variables and functions marked for export, along with + +o Shell variables and functions marked for export, along with variables exported for the command, passed in the environment. +o Traps caught by the shell are reset to the values inherited from the shell's parent, and traps ignored by the shell are ignored. - A command invoked in this separate environment cannot affect the + A command invoked in this separate environment cannot affect the shell's execution environment. A _s_u_b_s_h_e_l_l is a copy of the shell process. - Command substitution, commands grouped with parentheses, and asynchro- + Command substitution, commands grouped with parentheses, and asynchro- nous commands are invoked in a subshell environment that is a duplicate of the shell environment, except that traps caught by the shell are re- - set to the values that the shell inherited from its parent at invoca- - tion. Builtin commands that are invoked as part of a pipeline, except - possibly in the last element depending on the value of the llaassttppiippee - shell option, are also executed in a subshell environment. Changes - made to the subshell environment cannot affect the shell's execution + set to the values that the shell inherited from its parent at invoca- + tion. Builtin commands that are invoked as part of a pipeline, except + possibly in the last element depending on the value of the llaassttppiippee + shell option, are also executed in a subshell environment. Changes + made to the subshell environment cannot affect the shell's execution environment. - When the shell is in posix mode, subshells spawned to execute command - substitutions inherit the value of the --ee option from their parent - shell. When not in posix mode, bbaasshh clears the --ee option in such sub- - shells. See the description of the iinnhheerriitt__eerrrreexxiitt shell option below + When the shell is in posix mode, subshells spawned to execute command + substitutions inherit the value of the --ee option from their parent + shell. When not in posix mode, bbaasshh clears the --ee option in such sub- + shells. See the description of the iinnhheerriitt__eerrrreexxiitt shell option below for how to control this behavior when not in posix mode. - If a command is followed by a && and job control is not active, the de- + If a command is followed by a && and job control is not active, the de- fault standard input for the command is the empty file _/_d_e_v_/_n_u_l_l. Oth- - erwise, the invoked command inherits the file descriptors of the call- + erwise, the invoked command inherits the file descriptors of the call- ing shell as modified by redirections. EENNVVIIRROONNMMEENNTT - When a program is invoked it is given an array of strings called the + When a program is invoked it is given an array of strings called the _e_n_v_i_r_o_n_m_e_n_t. This is a list of _n_a_m_e-_v_a_l_u_e pairs, of the form _n_a_m_e=_v_a_l_u_e. - The shell provides several ways to manipulate the environment. On in- - vocation, the shell scans its own environment and creates a parameter - for each name found, automatically marking it for _e_x_p_o_r_t to child + The shell provides several ways to manipulate the environment. On in- + vocation, the shell scans its own environment and creates a parameter + for each name found, automatically marking it for _e_x_p_o_r_t to child processes. Executed commands inherit the environment. The eexxppoorrtt, ddee-- - ccllaarree --xx, and uunnsseett commands modify the environment by adding and - deleting parameters and functions. If the value of a parameter in the - environment is modified, the new value automatically 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 uunn-- - sseett or eexxppoorrtt --nn commands, plus any additions via the eexxppoorrtt and ddee-- + ccllaarree --xx, and uunnsseett commands modify the environment by adding and + deleting parameters and functions. If the value of a parameter in the + environment is modified, the new value automatically 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 uunn-- + sseett or eexxppoorrtt --nn commands, plus any additions via the eexxppoorrtt and ddee-- ccllaarree --xx commands. - If any parameter assignments, as described above in PPAARRAAMMEETTEERRSS, appear + If any parameter assignments, as described above in PPAARRAAMMEETTEERRSS, appear before a _s_i_m_p_l_e _c_o_m_m_a_n_d, the variable assignments are part of that com- mand's environment for as long as it executes. These assignment state- - ments affect only the environment seen by that command. If these as- - signments precede a call to a shell function, the variables are local + ments affect only the environment seen by that command. If these as- + signments precede a call to a shell function, the variables are local to the function and exported to that function's children. - If the --kk option is set (see the sseett builtin command below), then _a_l_l - parameter assignments are placed in the environment for a command, not + If the --kk option is set (see the sseett builtin command below), then _a_l_l + parameter assignments are placed in the environment for a command, not just those that precede the command name. - When bbaasshh invokes an external command, the variable __ is set to the + When bbaasshh invokes an external command, the variable __ is set to the full pathname of the command and passed to that command in its environ- ment. EEXXIITT SSTTAATTUUSS - The exit status of an executed command is the value returned by the + The exit status of an executed command is the value returned by the _w_a_i_t_p_i_d system call or equivalent function. Exit statuses fall between - 0 and 255, though, as explained below, the shell may use values above + 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. So while an exit status of zero indicates success, a + has succeeded. So while an exit status of zero indicates success, a non-zero exit status indicates failure. - When a command terminates on a fatal signal _N, bbaasshh uses the value of + When a command terminates on a fatal signal _N, bbaasshh uses the value of 128+_N as the exit status. - If a command is not found, the child process created to execute it re- - turns a status of 127. If a command is found but is not executable, + If a command is not found, the child process created to execute it re- + turns 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. - Shell builtin commands return a status of 0 (_t_r_u_e) if successful, and - non-zero (_f_a_l_s_e) if an error occurs while they execute. All builtins - return an exit status of 2 to indicate incorrect usage, generally in- + Shell builtin commands return a status of 0 (_t_r_u_e) if successful, and + non-zero (_f_a_l_s_e) if an error occurs while they execute. All builtins + return an exit status of 2 to indicate incorrect usage, generally in- valid options or missing arguments. The exit status of the last command is available in the special parame- ter $?. - BBaasshh itself returns the exit status of the last command executed, un- - less a syntax error occurs, in which case it exits with a non-zero + BBaasshh itself returns the exit status of the last command executed, un- + less a syntax error occurs, in which case it exits with a non-zero value. See also the eexxiitt builtin command below. SSIIGGNNAALLSS - When bbaasshh is interactive, in the absence of any traps, it ignores - SSIIGGTTEERRMM (so that kkiillll 00 does not kill an interactive shell), and + When bbaasshh is interactive, in the absence of any traps, it ignores + SSIIGGTTEERRMM (so that kkiillll 00 does not kill an interactive shell), and catches and handles SSIIGGIINNTT (so that the wwaaiitt builtin is interruptible). - When bbaasshh receives SSIIGGIINNTT, it breaks out of any executing loops. In + When bbaasshh receives SSIIGGIINNTT, it breaks out of any executing loops. In all cases, bbaasshh ignores SSIIGGQQUUIITT. If job control is in effect, bbaasshh ig- nores SSIIGGTTTTIINN, SSIIGGTTTTOOUU, and SSIIGGTTSSTTPP. @@ -3283,45 +3306,45 @@ SSIIGGNNAALLSS Non-builtin commands bbaasshh executes have signal handlers set to the val- ues inherited by the shell from its parent, unless ttrraapp sets them to be - ignored, in which case the child process will ignore them as well. - When job control is not in effect, asynchronous commands ignore SSIIGGIINNTT + ignored, in which case the child process will ignore them as well. + When job control is not in effect, asynchronous commands ignore SSIIGGIINNTT and SSIIGGQQUUIITT in addition to these inherited handlers. Commands run as a - result of command substitution ignore the keyboard-generated job con- + result of command substitution ignore the keyboard-generated job con- trol signals SSIIGGTTTTIINN, SSIIGGTTTTOOUU, and SSIIGGTTSSTTPP. - The shell exits by default upon receipt of a SSIIGGHHUUPP. Before exiting, - an interactive shell resends the SSIIGGHHUUPP to all jobs, running or - stopped. The shell sends SSIIGGCCOONNTT to stopped jobs to ensure that they - receive the SSIIGGHHUUPP (see JJOOBB CCOONNTTRROOLL below for more information about - running and stopped jobs). To prevent the shell from sending the sig- - nal to a particular job, remove it from the jobs table with the ddiissoowwnn - builtin (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below) or mark it not to receive + The shell exits by default upon receipt of a SSIIGGHHUUPP. Before exiting, + an interactive shell resends the SSIIGGHHUUPP to all jobs, running or + stopped. The shell sends SSIIGGCCOONNTT to stopped jobs to ensure that they + receive the SSIIGGHHUUPP (see JJOOBB CCOONNTTRROOLL below for more information about + running and stopped jobs). To prevent the shell from sending the sig- + nal to a particular job, remove it from the jobs table with the ddiissoowwnn + builtin (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below) or mark it not to receive SSIIGGHHUUPP using ddiissoowwnn --hh. - If the hhuuppoonneexxiitt shell option has been set using sshhoopptt, bbaasshh sends a + If the hhuuppoonneexxiitt shell option has been set using sshhoopptt, bbaasshh sends a SSIIGGHHUUPP to all jobs when an interactive login shell exits. - If bbaasshh is waiting for a command to complete and receives a signal for - which a trap has been set, it will not execute the trap until the com- + If bbaasshh is waiting for a command to complete and receives a signal for + which a trap has been set, it will not execute the trap until the com- mand completes. If bbaasshh is waiting for an asynchronous command via the - wwaaiitt builtin, and it receives a signal for which a trap has been set, - the wwaaiitt builtin will return immediately with an exit status greater + wwaaiitt builtin, and it receives a signal for which a trap has been set, + the wwaaiitt builtin will return immediately with an exit status greater than 128, immediately after which the shell executes the trap. - When job control is not enabled, and bbaasshh is waiting for a foreground + When job control is not enabled, and bbaasshh is waiting for a foreground command to complete, the shell receives keyboard-generated signals such - as SSIIGGIINNTT (usually generated by ^^CC) that users commonly intend to send + as SSIIGGIINNTT (usually generated by ^^CC) that users commonly intend to send to that command. This happens because the shell and the command are in - the same process group as the terminal, and ^^CC sends SSIIGGIINNTT to all - processes in that process group. Since bbaasshh does not enable job con- - trol by default when the shell is not interactive, this scenario is + the same process group as the terminal, and ^^CC sends SSIIGGIINNTT to all + processes in that process group. Since bbaasshh does not enable job con- + trol by default when the shell is not interactive, this scenario is most common in non-interactive shells. - When job control is enabled, and bbaasshh is waiting for a foreground com- - mand to complete, the shell does not receive keyboard-generated sig- - nals, because it is not in the same process group as the terminal. + When job control is enabled, and bbaasshh is waiting for a foreground com- + mand to complete, the shell does not receive keyboard-generated sig- + nals, because it is not in the same process group as the terminal. This scenario is most common in interactive shells, where bbaasshh attempts - to enable job control by default. See JJOOBB CCOONNTTRROOLL below for more in- + to enable job control by default. See JJOOBB CCOONNTTRROOLL below for more in- formation about process groups. When job control is not enabled, and bbaasshh receives SSIIGGIINNTT while waiting @@ -3331,168 +3354,168 @@ SSIIGGNNAALLSS 1. If the command terminates due to the SSIIGGIINNTT, bbaasshh concludes that the user meant to send the SSIIGGIINNTT to the shell as well, and acts on the SSIIGGIINNTT (e.g., by running a SSIIGGIINNTT trap, exiting a non-in- - teractive shell, or returning to the top level to read a new + teractive shell, or returning to the top level to read a new command). - 2. If the command does not terminate due to SSIIGGIINNTT, the program - handled the SSIIGGIINNTT itself and did not treat it as a fatal sig- - nal. In that case, bbaasshh does not treat SSIIGGIINNTT as a fatal sig- - nal, either, instead assuming that the SSIIGGIINNTT was used as part - of the program's normal operation (e.g., emacs uses it to abort + 2. If the command does not terminate due to SSIIGGIINNTT, the program + handled the SSIIGGIINNTT itself and did not treat it as a fatal sig- + nal. In that case, bbaasshh does not treat SSIIGGIINNTT as a fatal sig- + nal, either, instead assuming that the SSIIGGIINNTT was used as part + of the program's normal operation (e.g., emacs uses it to abort editing commands) or deliberately discarded. However, bbaasshh will - run any trap set on SSIIGGIINNTT, as it does with any other trapped - signal it receives while it is waiting for the foreground com- + run any trap set on SSIIGGIINNTT, as it does with any other trapped + signal it receives while it is waiting for the foreground com- mand to complete, for compatibility. - When job control is enabled, bbaasshh does not receive keyboard-generated - signals such as SSIIGGIINNTT while it is waiting for a foreground command. - An interactive shell does not pay attention to the SSIIGGIINNTT, even if the - foreground command terminates as a result, other than noting its exit - status. If the shell is not interactive, and the foreground command - terminates due to the SSIIGGIINNTT, bbaasshh pretends it received the SSIIGGIINNTT it- + When job control is enabled, bbaasshh does not receive keyboard-generated + signals such as SSIIGGIINNTT while it is waiting for a foreground command. + An interactive shell does not pay attention to the SSIIGGIINNTT, even if the + foreground command terminates as a result, other than noting its exit + status. If the shell is not interactive, and the foreground command + terminates due to the SSIIGGIINNTT, bbaasshh pretends it received the SSIIGGIINNTT it- self (scenario 1 above), for compatibility. JJOOBB CCOONNTTRROOLL _J_o_b _c_o_n_t_r_o_l refers to the ability to selectively stop (_s_u_s_p_e_n_d) the ex- - ecution of processes and continue (_r_e_s_u_m_e) their execution at a later - point. A user typically employs this facility via an interactive in- + ecution of processes and continue (_r_e_s_u_m_e) their execution at a later + point. A user typically employs this facility via an interactive in- terface supplied jointly by the operating system kernel's terminal dri- ver and bbaasshh. - The shell associates a _j_o_b with each pipeline. It keeps a table of - currently executing jobs, which the jjoobbss command will display. Each - job has a _j_o_b _n_u_m_b_e_r, which jjoobbss displays between brackets. Job num- - bers start at 1. When bbaasshh starts a job asynchronously (in the _b_a_c_k_- + The shell associates a _j_o_b with each pipeline. It keeps a table of + currently executing jobs, which the jjoobbss command will display. Each + job has a _j_o_b _n_u_m_b_e_r, which jjoobbss displays between brackets. Job num- + bers start at 1. When bbaasshh starts a job asynchronously (in the _b_a_c_k_- _g_r_o_u_n_d), it prints a line that looks like: [1] 25647 indicating that this job is job number 1 and that the process ID of the last process in the pipeline associated with this job is 25647. All of - the processes in a single pipeline are members of the same job. BBaasshh + the processes in a single pipeline are members of the same job. BBaasshh uses the _j_o_b abstraction as the basis for job control. - To facilitate the implementation of the user interface to job control, + To facilitate the implementation of the user interface to job control, each process has a _p_r_o_c_e_s_s _g_r_o_u_p _I_D, and the operating system maintains - the notion of a _c_u_r_r_e_n_t _t_e_r_m_i_n_a_l _p_r_o_c_e_s_s _g_r_o_u_p _I_D. This terminal + the notion of a _c_u_r_r_e_n_t _t_e_r_m_i_n_a_l _p_r_o_c_e_s_s _g_r_o_u_p _I_D. This terminal process group ID is associated with the _c_o_n_t_r_o_l_l_i_n_g _t_e_r_m_i_n_a_l. - Processes that have the same process group ID are said to be part of - the same _p_r_o_c_e_s_s _g_r_o_u_p. Members of the _f_o_r_e_g_r_o_u_n_d process group - (processes whose process group ID is equal to the current terminal - process group ID) receive keyboard-generated signals such as SSIIGGIINNTT. - Processes in the foreground process group are said to be _f_o_r_e_g_r_o_u_n_d - processes. _B_a_c_k_g_r_o_u_n_d processes are those whose process group ID dif- + Processes that have the same process group ID are said to be part of + the same _p_r_o_c_e_s_s _g_r_o_u_p. Members of the _f_o_r_e_g_r_o_u_n_d process group + (processes whose process group ID is equal to the current terminal + process group ID) receive keyboard-generated signals such as SSIIGGIINNTT. + Processes in the foreground process group are said to be _f_o_r_e_g_r_o_u_n_d + processes. _B_a_c_k_g_r_o_u_n_d processes are those whose process group ID dif- fers from the controlling terminal's; such processes are immune to key- board-generated signals. Only foreground processes are allowed to read from or, if the user so specifies with "stty tostop", write to the con- - trolling terminal. The system sends a SSIIGGTTTTIINN ((SSIIGGTTTTOOUU)) signal to + trolling terminal. The system sends a SSIIGGTTTTIINN ((SSIIGGTTTTOOUU)) signal to background processes which attempt to read from (write to when "tostop" is in effect) the terminal, which, unless caught, suspends the process. - If the operating system on which bbaasshh is running supports job control, + If the operating system on which bbaasshh is running supports job control, bbaasshh contains facilities to use it. Typing the _s_u_s_p_e_n_d character (typ- ically ^^ZZ, Control-Z) while a process is running stops that process and - returns control to bbaasshh. Typing the _d_e_l_a_y_e_d _s_u_s_p_e_n_d character (typi- - cally ^^YY, Control-Y) causes the process stop when it attempts to read - input from the terminal, and returns control to bbaasshh. The user then - manipulates the state of this job, using the bbgg command to continue it - in the background, the ffgg command to continue it in the foreground, or - the kkiillll command to kill it. The suspend character takes effect imme- - diately, and has the additional side effect of discarding any pending + returns control to bbaasshh. Typing the _d_e_l_a_y_e_d _s_u_s_p_e_n_d character (typi- + cally ^^YY, Control-Y) causes the process stop when it attempts to read + input from the terminal, and returns control to bbaasshh. The user then + manipulates the state of this job, using the bbgg command to continue it + in the background, the ffgg command to continue it in the foreground, or + the kkiillll command to kill it. The suspend character takes effect imme- + diately, and has the additional side effect of discarding any pending output and typeahead. To force a background process to stop, or stop a - process that's not associated with the current terminal session, send + process that's not associated with the current terminal session, send it the SSIIGGSSTTOOPP signal using kkiillll. There are a number of ways to refer to a job in the shell. The %% char- acter introduces a job specification (jobspec). - Job number _n may be referred to as %%nn. 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, %%ccee refers to a job whose - command name begins with ccee. Using %%??ccee, on the other hand, refers to + Job number _n may be referred to as %%nn. 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, %%ccee refers to a job whose + command name begins with ccee. Using %%??ccee, on the other hand, refers to any job containing the string ccee in its command line. If the prefix or substring matches more than one job, bbaasshh reports an error. - The symbols %%%% and %%++ refer to the shell's notion of the _c_u_r_r_e_n_t _j_o_b. - A single % (with no accompanying job specification) also refers to the - current job. %%-- refers to the _p_r_e_v_i_o_u_s _j_o_b. When a job starts in the + The symbols %%%% and %%++ refer to the shell's notion of the _c_u_r_r_e_n_t _j_o_b. + A single % (with no accompanying job specification) also refers to the + current job. %%-- refers to the _p_r_e_v_i_o_u_s _j_o_b. When a job starts in the background, a job stops while in the foreground, or a job is resumed in - the background, it becomes the current job. The job that was the cur- - rent job becomes the previous job. When the current job terminates, - the previous job becomes the current job. If there is only a single - job, %%++ and %%-- can both be used to refer to that job. In output per- + the background, it becomes the current job. The job that was the cur- + rent job becomes the previous job. When the current job terminates, + the previous job becomes the current job. If there is only a single + job, %%++ and %%-- can both be used to refer to that job. In output per- taining to jobs (e.g., the output of the jjoobbss command), the current job is always marked with a ++, and the previous job with a --. - Simply naming a job can be used to bring it into the foreground: %%11 is - a synonym for "fg %1", bringing job 1 from the background into the + Simply naming a job can be used to bring it into the foreground: %%11 is + a synonym for "fg %1", bringing job 1 from the background into the foreground. Similarly, "%1 &" resumes job 1 in the background, equiva- lent to "bg %1". - The shell learns immediately whenever a job changes state. Normally, - bbaasshh waits until it is about to print a prompt before notifying the - user about changes in a job's status so as to not interrupt any other - output, though it will notify of changes in a job's status after a - foreground command in a list completes, before executing the next com- - mand in the list. If the --bb option to the sseett builtin command is en- + The shell learns immediately whenever a job changes state. Normally, + bbaasshh waits until it is about to print a prompt before notifying the + user about changes in a job's status so as to not interrupt any other + output, though it will notify of changes in a job's status after a + foreground command in a list completes, before executing the next com- + mand in the list. If the --bb option to the sseett builtin command is en- abled, bbaasshh reports status changes immediately. BBaasshh executes any trap on SSIIGGCCHHLLDD for each child that terminates. When a job terminates and bbaasshh notifies the user about it, bbaasshh removes - the job from the table. It will not appear in jjoobbss output, but wwaaiitt - will report its exit status, as long as it's supplied the process ID - associated with the job as an argument. When the table is empty, job + the job from the table. It will not appear in jjoobbss output, but wwaaiitt + will report its exit status, as long as it's supplied the process ID + associated with the job as an argument. When the table is empty, job numbers start over at 1. - If a user attempts to exit bbaasshh while jobs are stopped (or, if the - cchheecckkjjoobbss shell option has been enabled using the sshhoopptt builtin, run- + If a user attempts to exit bbaasshh while jobs are stopped (or, if the + cchheecckkjjoobbss shell option has been enabled using the sshhoopptt builtin, run- ning), the shell prints a warning message, and, if the cchheecckkjjoobbss option - is enabled, lists the jobs and their statuses. The jjoobbss command may + is enabled, lists the jobs and their statuses. The jjoobbss command may then be used to inspect their status. If the user immediately attempts - to exit again, without an intervening command, bbaasshh does not print an- + to exit again, without an intervening command, bbaasshh does not print an- other warning, and terminates any stopped jobs. - When the shell is waiting for a job or process using the wwaaiitt builtin, - and job control is enabled, wwaaiitt will return when the job changes + When the shell is waiting for a job or process using the wwaaiitt builtin, + and job control is enabled, wwaaiitt will return when the job changes state. The --ff option causes wwaaiitt to wait until the job or process ter- minates before returning. PPRROOMMPPTTIINNGG When executing interactively, bbaasshh displays the primary prompt PPSS11 when - it is ready to read a command, and the secondary prompt PPSS22 when it + it is ready to read a command, and the secondary prompt PPSS22 when it needs more input to complete a command. - BBaasshh examines the value of the array variable PPRROOMMPPTT__CCOOMMMMAANNDD just be- - fore printing each primary prompt. If any elements in PPRROOMMPPTT__CCOOMMMMAANNDD - are set and non-null, Bash executes each value, in numeric order, just - as if it had been typed on the command line. BBaasshh displays PPSS00 after + BBaasshh examines the value of the array variable PPRROOMMPPTT__CCOOMMMMAANNDD just be- + fore printing each primary prompt. If any elements in PPRROOMMPPTT__CCOOMMMMAANNDD + are set and non-null, Bash executes each value, in numeric order, just + as if it had been typed on the command line. BBaasshh displays PPSS00 after it reads a command but before executing it. - BBaasshh displays PPSS44 as described above before tracing each command when + BBaasshh displays PPSS44 as described above before tracing each command when the --xx option is enabled. BBaasshh allows the prompt strings PPSS00, PPSS11, PPSS22, and PPSS44, to be customized - by inserting a number of backslash-escaped special characters that are + by inserting a number of backslash-escaped special characters that are decoded as follows: \\aa An ASCII bell character (07). - \\dd The date in "Weekday Month Date" format (e.g., "Tue May + \\dd The date in "Weekday Month Date" format (e.g., "Tue May 26"). \\DD{{_f_o_r_m_a_t}} The _f_o_r_m_a_t is passed to _s_t_r_f_t_i_m_e(3) and the result is in- serted into the prompt string; an empty _f_o_r_m_a_t results in - a locale-specific time representation. The braces are + a locale-specific time representation. The braces are required. \\ee An ASCII escape character (033). \\hh The hostname up to the first ".". \\HH The hostname. \\jj The number of jobs currently managed by the shell. - \\ll The basename of the shell's terminal device name (e.g., + \\ll The basename of the shell's terminal device name (e.g., "ttys0"). \\nn A newline. \\rr A carriage return. - \\ss The name of the shell: the basename of $$00 (the portion + \\ss The name of the shell: the basename of $$00 (the portion following the final slash). \\tt The current time in 24-hour HH:MM:SS format. \\TT The current time in 12-hour HH:MM:SS format. @@ -3501,104 +3524,104 @@ PPRROOMMPPTTIINNGG \\uu The username of the current user. \\vv The bbaasshh version (e.g., 2.00). \\VV The bbaasshh release, version + patch level (e.g., 2.00.0) - \\ww The value of the PPWWDD shell variable ($$PPWWDD), with $$HHOOMMEE - abbreviated with a tilde (uses the value of the + \\ww The value of the PPWWDD shell variable ($$PPWWDD), with $$HHOOMMEE + abbreviated with a tilde (uses the value of the PPRROOMMPPTT__DDIIRRTTRRIIMM variable). - \\WW The basename of $$PPWWDD, with $$HHOOMMEE abbreviated with a + \\WW The basename of $$PPWWDD, with $$HHOOMMEE abbreviated with a tilde. \\!! The history number of this command. \\## The command number of this command. \\$$ If the effective UID is 0, a ##, otherwise a $$. \\_n_n_n The character corresponding to the octal number _n_n_n. \\\\ A backslash. - \\[[ Begin a sequence of non-printing characters, which could - be used to embed a terminal control sequence into the + \\[[ Begin a sequence of non-printing characters, which could + be used to embed a terminal control sequence into the prompt. \\]] End a sequence of non-printing characters. - The command number and the history number are usually different: the - history number of a command is its position in the history list, which - may include commands restored from the history file (see HHIISSTTOORRYY be- - low), while the command number is the position in the sequence of com- - mands 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 + 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 HHIISSTTOORRYY be- + low), while the command number is the position in the sequence of com- + mands 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 pprroommppttvvaarrss shell option (see the description of the sshhoopptt command under - SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). This can have unwanted side effects if - escaped portions of the string appear within command substitution or + SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). This can have unwanted side effects if + escaped portions of the string appear within command substitution or contain characters special to word expansion. RREEAADDLLIINNEE - This is the library that handles reading input when using an interac- - tive shell, unless the ----nnooeeddiittiinngg option is supplied at shell invoca- - tion. Line editing is also used when using the --ee option to the rreeaadd + This is the library that handles reading input when using an interac- + tive shell, unless the ----nnooeeddiittiinngg option is supplied at shell invoca- + tion. Line editing is also used when using the --ee option to the rreeaadd builtin. By default, the line editing commands are similar to those of emacs; a vi-style line editing interface is also available. Line edit- - ing can be enabled at any time using the --oo eemmaaccss or --oo vvii options to - the sseett builtin (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). To turn off line - editing after the shell is running, use the ++oo eemmaaccss or ++oo vvii options + ing can be enabled at any time using the --oo eemmaaccss or --oo vvii options to + the sseett builtin (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). To turn off line + editing after the shell is running, use the ++oo eemmaaccss or ++oo vvii options to the sseett builtin. RReeaaddlliinnee NNoottaattiioonn - This section uses Emacs-style editing concepts and uses its notation - for keystrokes. Control keys are denoted by C-_k_e_y, e.g., C-n means - Control-N. Similarly, _m_e_t_a keys are denoted by M-_k_e_y, so M-x means + This section uses Emacs-style editing concepts and uses its notation + for keystrokes. Control keys are denoted by C-_k_e_y, e.g., C-n means + Control-N. Similarly, _m_e_t_a keys are denoted by M-_k_e_y, so M-x means Meta-X. The Meta key is often labeled "Alt" or "Option". - On keyboards without a _M_e_t_a key, M-_x means ESC _x, i.e., press and re- - lease the Escape key, then press and release the _x key, in sequence. - This makes ESC the _m_e_t_a _p_r_e_f_i_x. The combination M-C-_x means ESC Con- - trol-_x: press and release the Escape key, then press and hold the Con- + On keyboards without a _M_e_t_a key, M-_x means ESC _x, i.e., press and re- + lease the Escape key, then press and release the _x key, in sequence. + This makes ESC the _m_e_t_a _p_r_e_f_i_x. The combination M-C-_x means ESC Con- + trol-_x: press and release the Escape key, then press and hold the Con- trol key while pressing the _x key, then release both. - On some keyboards, the Meta key modifier produces characters with the - eighth bit (0200) set. You can use the eennaabbllee--mmeettaa--kkeeyy variable to - control whether or not it does this, if the keyboard allows it. On - many others, the terminal or terminal emulator converts the metafied - key to a key sequence beginning with ESC as described in the preceding + On some keyboards, the Meta key modifier produces characters with the + eighth bit (0200) set. You can use the eennaabbllee--mmeettaa--kkeeyy variable to + control whether or not it does this, if the keyboard allows it. On + many others, the terminal or terminal emulator converts the metafied + key to a key sequence beginning with ESC as described in the preceding paragraph. - If your _M_e_t_a key produces a key sequence with the ESC meta prefix, you - can make M-_k_e_y key bindings you specify (see RReeaaddlliinnee KKeeyy BBiinnddiinnggss be- + If your _M_e_t_a key produces a key sequence with the ESC meta prefix, you + can make M-_k_e_y key bindings you specify (see RReeaaddlliinnee KKeeyy BBiinnddiinnggss be- low) do the same thing by setting the ffoorrccee--mmeettaa--pprreeffiixx variable. RReeaaddlliinnee commands may be given numeric _a_r_g_u_m_e_n_t_s, 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., kkiillll--lliinnee) makes that command act - in a backward direction. Commands whose behavior with arguments devi- + 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., kkiillll--lliinnee) makes that command act + in a backward direction. Commands whose behavior with arguments devi- ates from this are noted below. - The _p_o_i_n_t is the current cursor position, and _m_a_r_k refers to a saved + The _p_o_i_n_t is the current cursor position, and _m_a_r_k refers to a saved cursor position. The text between the point and mark is referred to as the _r_e_g_i_o_n. RReeaaddlliinnee has the concept of an _a_c_t_i_v_e _r_e_g_i_o_n: when the re- - gion is active, rreeaaddlliinnee redisplay highlights the region using the + gion is active, rreeaaddlliinnee redisplay highlights the region using the value of the aaccttiivvee--rreeggiioonn--ssttaarrtt--ccoolloorr variable. The eennaabbllee--aaccttiivvee--rree-- - ggiioonn variable turns this on and off. Several commands set the region + ggiioonn variable turns this on and off. Several commands set the region to active; those are noted below. - When a command is described as _k_i_l_l_i_n_g text, the text deleted is saved + When a command is described as _k_i_l_l_i_n_g text, the text deleted is saved for possible future retrieval (_y_a_n_k_i_n_g). The killed text is saved in a - _k_i_l_l _r_i_n_g. Consecutive kills accumulate the deleted text into one + _k_i_l_l _r_i_n_g. Consecutive kills accumulate the deleted text 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. RReeaaddlliinnee IInniittiiaalliizzaattiioonn - RReeaaddlliinnee is customized by putting commands in an initialization file - (the _i_n_p_u_t_r_c file). The name of this file is taken from the value of - the IINNPPUUTTRRCC shell variable. If that variable is unset, the default is - _~_/_._i_n_p_u_t_r_c. If that file does not exist or cannot be read, rreeaaddlliinnee - looks for _/_e_t_c_/_i_n_p_u_t_r_c. When a program that uses the rreeaaddlliinnee library - starts up, rreeaaddlliinnee reads the initialization file and sets the key + RReeaaddlliinnee is customized by putting commands in an initialization file + (the _i_n_p_u_t_r_c file). The name of this file is taken from the value of + the IINNPPUUTTRRCC shell variable. If that variable is unset, the default is + _~_/_._i_n_p_u_t_r_c. If that file does not exist or cannot be read, rreeaaddlliinnee + looks for _/_e_t_c_/_i_n_p_u_t_r_c. When a program that uses the rreeaaddlliinnee library + starts up, rreeaaddlliinnee reads the initialization file and sets the key bindings and variables found there, before reading any user input. - There are only a few basic constructs allowed in the inputrc file. + There are only a few basic constructs allowed in the inputrc file. Blank lines are ignored. Lines beginning with a ## are comments. Lines beginning with a $$ indicate conditional constructs. Other lines denote key bindings and variable settings. The default key-bindings in this section may be changed using key bind- - ing commands in the _i_n_p_u_t_r_c file. Programs that use the rreeaaddlliinnee li- + ing commands in the _i_n_p_u_t_r_c file. Programs that use the rreeaaddlliinnee li- brary, including bbaasshh, may add their own commands and bindings. For example, placing @@ -3607,26 +3630,26 @@ RREEAADDLLIINNEE or C-Meta-u: universal-argument - into the _i_n_p_u_t_r_c would make M-C-u execute the rreeaaddlliinnee command _u_n_i_v_e_r_- + into the _i_n_p_u_t_r_c would make M-C-u execute the rreeaaddlliinnee command _u_n_i_v_e_r_- _s_a_l_-_a_r_g_u_m_e_n_t. - Key bindings may contain the following symbolic character names: _D_E_L, - _E_S_C, _E_S_C_A_P_E, _L_F_D, _N_E_W_L_I_N_E, _R_E_T, _R_E_T_U_R_N, _R_U_B_O_U_T (a destructive back- + Key bindings may contain the following symbolic character names: _D_E_L, + _E_S_C, _E_S_C_A_P_E, _L_F_D, _N_E_W_L_I_N_E, _R_E_T, _R_E_T_U_R_N, _R_U_B_O_U_T (a destructive back- space), _S_P_A_C_E, _S_P_C, and _T_A_B. - In addition to command names, rreeaaddlliinnee allows keys to be bound to a + In addition to command names, rreeaaddlliinnee allows keys to be bound to a string that is inserted when the key is pressed (a _m_a_c_r_o). The differ- - ence between a macro and a command is that a macro is enclosed in sin- + ence between a macro and a command is that a macro is enclosed in sin- gle or double quotes. RReeaaddlliinnee KKeeyy BBiinnddiinnggss - The syntax for controlling key bindings in the _i_n_p_u_t_r_c 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 key sequence may - be specified in one of two ways: as a symbolic key name, possibly with - _M_e_t_a_- or _C_o_n_t_r_o_l_- prefixes, or as a key sequence composed of one or - more characters enclosed in double quotes. The key sequence and name - are separated by a colon. There can be no whitespace between the name + The syntax for controlling key bindings in the _i_n_p_u_t_r_c 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 key sequence may + be specified in one of two ways: as a symbolic key name, possibly with + _M_e_t_a_- or _C_o_n_t_r_o_l_- prefixes, or as a key sequence composed of one or + more characters enclosed in double quotes. The key sequence and name + are separated by a colon. There can be no whitespace between the name and the colon. When using the form kkeeyynnaammee:_f_u_n_c_t_i_o_n_-_n_a_m_e or _m_a_c_r_o, _k_e_y_n_a_m_e is the name @@ -3636,15 +3659,15 @@ RREEAADDLLIINNEE Meta-Rubout: backward-kill-word Control-o: "> output" - In the above example, _C_-_u is bound to the function uunniivveerrssaall--aarrgguummeenntt, - _M_-_D_E_L is bound to the function bbaacckkwwaarrdd--kkiillll--wwoorrdd, and _C_-_o is bound to - run the macro expressed on the right hand side (that is, to insert the + In the above example, _C_-_u is bound to the function uunniivveerrssaall--aarrgguummeenntt, + _M_-_D_E_L is bound to the function bbaacckkwwaarrdd--kkiillll--wwoorrdd, and _C_-_o is bound to + run the macro expressed on the right hand side (that is, to insert the text "> output" into the line). - In the second form, ""kkeeyysseeqq"":_f_u_n_c_t_i_o_n_-_n_a_m_e or _m_a_c_r_o, kkeeyysseeqq differs - from kkeeyynnaammee 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 + In the second form, ""kkeeyysseeqq"":_f_u_n_c_t_i_o_n_-_n_a_m_e or _m_a_c_r_o, kkeeyysseeqq differs + from kkeeyynnaammee 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 none of the symbolic character names are recognized. "\C-u": universal-argument @@ -3652,21 +3675,21 @@ RREEAADDLLIINNEE "\e[11~": "Function Key 1" In this example, _C_-_u is again bound to the function uunniivveerrssaall--aarrgguummeenntt. - _C_-_x _C_-_r is bound to the function rree--rreeaadd--iinniitt--ffiillee, and _E_S_C _[ _1 _1 _~ is + _C_-_x _C_-_r is bound to the function rree--rreeaadd--iinniitt--ffiillee, and _E_S_C _[ _1 _1 _~ is bound to insert the text "Function Key 1". - The full set of GNU Emacs style escape sequences available when speci- + The full set of GNU Emacs style escape sequences available when speci- fying key sequences is \\CC-- A control prefix. - \\MM-- Adding the meta prefix or converting the following char- - acter to a meta character, as described below under + \\MM-- Adding the meta prefix or converting the following char- + acter to a meta character, as described below under ffoorrccee--mmeettaa--pprreeffiixx. \\ee An escape character. \\\\ Backslash. \\"" Literal ", a double quote. \\'' Literal ', a single quote. - In addition to the GNU Emacs style escape sequences, a second set of + In addition to the GNU Emacs style escape sequences, a second set of backslash escapes is available: \\aa alert (bell) \\bb backspace @@ -3676,20 +3699,20 @@ RREEAADDLLIINNEE \\rr carriage return \\tt horizontal tab \\vv vertical tab - \\_n_n_n The eight-bit character whose value is the octal value + \\_n_n_n The eight-bit character whose value is the octal value _n_n_n (one to three digits). - \\xx_H_H The eight-bit character whose value is the hexadecimal + \\xx_H_H The eight-bit character whose value is the hexadecimal value _H_H (one or two hex digits). When entering the text of a macro, single or double quotes must be used to indicate a macro definition. Unquoted text is assumed to be a func- - tion name. The backslash escapes described above are expanded in the - macro body. Backslash quotes any other character in the macro text, + tion name. The backslash escapes described above are expanded in the + macro body. Backslash quotes any other character in the macro text, including " and '. - BBaasshh will display or modify the current rreeaaddlliinnee key bindings with the + BBaasshh will display or modify the current rreeaaddlliinnee key bindings with the bbiinndd builtin command. The --oo eemmaaccss or --oo vvii options to the sseett builtin - (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below) change the editing mode during in- + (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below) change the editing mode during in- teractive use. RReeaaddlliinnee VVaarriiaabblleess @@ -3700,248 +3723,248 @@ RREEAADDLLIINNEE sseett _v_a_r_i_a_b_l_e_-_n_a_m_e _v_a_l_u_e or using the bbiinndd builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). - Except where noted, rreeaaddlliinnee variables can take the values OOnn or OOffff - (without regard to case). Unrecognized variable names are ignored. + Except where noted, rreeaaddlliinnee variables can take the values OOnn or OOffff + (without regard to case). Unrecognized variable names are ignored. When rreeaaddlliinnee reads a variable value, empty or null values, "on" (case- - insensitive), and "1" are equivalent to OOnn. All other values are + insensitive), and "1" are equivalent to OOnn. All other values are equivalent to OOffff. - The bbiinndd --VV command lists the current rreeaaddlliinnee variable names and val- + The bbiinndd --VV command lists the current rreeaaddlliinnee variable names and val- ues (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). The variables and their default values are: aaccttiivvee--rreeggiioonn--ssttaarrtt--ccoolloorr - A string variable that controls the text color and background - when displaying the text in the active region (see the descrip- - tion of eennaabbllee--aaccttiivvee--rreeggiioonn below). This string must not take + A string variable that controls the text color and background + when displaying the text in the active region (see the descrip- + tion of eennaabbllee--aaccttiivvee--rreeggiioonn below). This string must not take up any physical character positions on the display, so it should - consist only of terminal escape sequences. It is output to the - terminal before displaying the text in the active region. This - variable is reset to the default value whenever the terminal - type changes. The default value is the string that puts the - terminal in standout mode, as obtained from the terminal's ter- + consist only of terminal escape sequences. It is output to the + terminal before displaying the text in the active region. This + variable is reset to the default value whenever the terminal + type changes. The default value is the string that puts the + terminal in standout mode, as obtained from the terminal's ter- minfo description. A sample value might be "\e[01;33m". aaccttiivvee--rreeggiioonn--eenndd--ccoolloorr - A string variable that "undoes" the effects of aaccttiivvee--rree-- - ggiioonn--ssttaarrtt--ccoolloorr and restores "normal" terminal display appear- - ance after displaying text in the active region. This string - must not take up any physical character positions on the dis- - play, so it should consist only of terminal escape sequences. - It is output to the terminal after displaying the text in the - active region. This variable is reset to the default value - whenever the terminal type changes. The default value is the - string that restores the terminal from standout mode, as ob- + A string variable that "undoes" the effects of aaccttiivvee--rree-- + ggiioonn--ssttaarrtt--ccoolloorr and restores "normal" terminal display appear- + ance after displaying text in the active region. This string + must not take up any physical character positions on the dis- + play, so it should consist only of terminal escape sequences. + It is output to the terminal after displaying the text in the + active region. This variable is reset to the default value + whenever the terminal type changes. The default value is the + string that restores the terminal from standout mode, as ob- tained from the terminal's terminfo description. A sample value might be "\e[0m". bbeellll--ssttyyllee ((aauuddiibbllee)) - Controls what happens when rreeaaddlliinnee wants to ring the terminal + Controls what happens when rreeaaddlliinnee wants to ring the terminal bell. If set to nnoonnee, rreeaaddlliinnee never rings the bell. If set to - vviissiibbllee, rreeaaddlliinnee uses a visible bell if one is available. If + vviissiibbllee, rreeaaddlliinnee uses a visible bell if one is available. If set to aauuddiibbllee, rreeaaddlliinnee attempts to ring the terminal's bell. bbiinndd--ttttyy--ssppeecciiaall--cchhaarrss ((OOnn)) - If set to OOnn, rreeaaddlliinnee attempts to bind the control characters - that are treated specially by the kernel's terminal driver to + If set to OOnn, rreeaaddlliinnee attempts to bind the control characters + that are treated specially by the kernel's terminal driver to their rreeaaddlliinnee equivalents. These override the default rreeaaddlliinnee bindings described here. Type "stty -a" at a bbaasshh prompt to see - your current terminal settings, including the special control - characters (usually cccchhaarrss). This binding takes place on each + your current terminal settings, including the special control + characters (usually cccchhaarrss). This binding takes place on each call to rreeaaddlliinnee, so changes made by "stty" can take effect. bblliinnkk--mmaattcchhiinngg--ppaarreenn ((OOffff)) If set to OOnn, rreeaaddlliinnee attempts to briefly move the cursor to an opening parenthesis when a closing parenthesis is inserted. ccoolloorreedd--ccoommpplleettiioonn--pprreeffiixx ((OOffff)) - If set to OOnn, when listing completions, rreeaaddlliinnee displays the + If set to OOnn, when listing completions, rreeaaddlliinnee displays the common prefix of the set of possible completions using a differ- - ent color. The color definitions are taken from the value of + ent color. The color definitions are taken from the value of the LLSS__CCOOLLOORRSS environment variable. If there is a color defini- tion in $$LLSS__CCOOLLOORRSS for the custom suffix ".readline-colored-com- - pletion-prefix", rreeaaddlliinnee uses this color for the common prefix + pletion-prefix", rreeaaddlliinnee uses this color for the common prefix instead of its default. ccoolloorreedd--ssttaattss ((OOffff)) - If set to OOnn, rreeaaddlliinnee displays possible completions using dif- - ferent colors to indicate their file type. The color defini- - tions are taken from the value of the LLSS__CCOOLLOORRSS environment + If set to OOnn, rreeaaddlliinnee displays possible completions using dif- + ferent colors to indicate their file type. The color defini- + tions are taken from the value of the LLSS__CCOOLLOORRSS environment variable. ccoommmmeenntt--bbeeggiinn (("##")) - The string that the rreeaaddlliinnee iinnsseerrtt--ccoommmmeenntt command inserts. - This command is bound to MM--## in emacs mode and to ## in vi com- + The string that the rreeaaddlliinnee iinnsseerrtt--ccoommmmeenntt command inserts. + This command is bound to MM--## in emacs mode and to ## in vi com- mand mode. ccoommpplleettiioonn--ddiissppllaayy--wwiiddtthh ((--11)) - The number of screen columns used to display possible matches - when performing completion. The value is ignored if it is less - than 0 or greater than the terminal screen width. A value of 0 - causes matches to be displayed one per line. The default value + The number of screen columns used to display possible matches + when performing completion. The value is ignored if it is less + than 0 or greater than the terminal screen width. A value of 0 + causes matches to be displayed one per line. The default value is -1. ccoommpplleettiioonn--iiggnnoorree--ccaassee ((OOffff)) If set to OOnn, rreeaaddlliinnee performs filename matching and completion in a case-insensitive fashion. ccoommpplleettiioonn--mmaapp--ccaassee ((OOffff)) - If set to OOnn, and ccoommpplleettiioonn--iiggnnoorree--ccaassee is enabled, rreeaaddlliinnee - treats hyphens (_-) and underscores (__) as equivalent when per- + If set to OOnn, and ccoommpplleettiioonn--iiggnnoorree--ccaassee is enabled, rreeaaddlliinnee + treats hyphens (_-) and underscores (__) as equivalent when per- forming case-insensitive filename matching and completion. ccoommpplleettiioonn--pprreeffiixx--ddiissppllaayy--lleennggtthh ((00)) - The maximum 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, rreeaaddlliinnee replaces common + The maximum 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, rreeaaddlliinnee replaces common prefixes longer than this value with an ellipsis when displaying possible completions. If a completion begins with a period, and - eeaaddlliinnee is completing filenames, it uses three underscores in- + eeaaddlliinnee is completing filenames, it uses three underscores in- stead of an ellipsis. ccoommpplleettiioonn--qquueerryy--iitteemmss ((110000)) - This determines when the user is queried about viewing the num- - ber of possible completions generated by the ppoossssiibbllee--ccoommppllee-- - ttiioonnss 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, rreeaaddlliinnee - asks whether or not the user wishes to view them; otherwise - rreeaaddlliinnee simply lists them on the terminal. A zero value means + This determines when the user is queried about viewing the num- + ber of possible completions generated by the ppoossssiibbllee--ccoommppllee-- + ttiioonnss 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, rreeaaddlliinnee + asks whether or not the user wishes to view them; otherwise + rreeaaddlliinnee simply lists them on the terminal. A zero value means rreeaaddlliinnee should never ask; negative values are treated as zero. ccoonnvveerrtt--mmeettaa ((OOnn)) - If set to OOnn, rreeaaddlliinnee converts characters it reads that have - the eighth bit set to an ASCII key sequence by clearing the + If set to OOnn, rreeaaddlliinnee converts characters it reads that have + the eighth bit set to an ASCII key sequence by clearing the eighth bit and prefixing it with an escape character (converting - the character to have the meta prefix). The default is _O_n, but - rreeaaddlliinnee sets it to _O_f_f if the locale contains characters whose + the character to have the meta prefix). The default is _O_n, but + rreeaaddlliinnee sets it to _O_f_f if the locale contains characters whose encodings may include bytes with the eighth bit set. This vari- - able is dependent on the LLCC__CCTTYYPPEE locale category, and may - change if the locale changes. This variable also affects key + able is dependent on the LLCC__CCTTYYPPEE locale category, and may + change if the locale changes. This variable also affects key bindings; see the description of ffoorrccee--mmeettaa--pprreeffiixx below. ddiissaabbllee--ccoommpplleettiioonn ((OOffff)) - If set to OOnn, rreeaaddlliinnee inhibits word completion. Completion + If set to OOnn, rreeaaddlliinnee inhibits word completion. Completion characters are inserted into the line as if they had been mapped to sseellff--iinnsseerrtt. eecchhoo--ccoonnttrrooll--cchhaarraacctteerrss ((OOnn)) - When set to OOnn, on operating systems that indicate they support + When set to OOnn, on operating systems that indicate they support it, rreeaaddlliinnee echoes a character corresponding to a signal gener- ated from the keyboard. eeddiittiinngg--mmooddee ((eemmaaccss)) - Controls whether rreeaaddlliinnee uses a set of key bindings similar to + Controls whether rreeaaddlliinnee uses a set of key bindings similar to _E_m_a_c_s or _v_i. eeddiittiinngg--mmooddee can be set to either eemmaaccss or vvii. eemmaaccss--mmooddee--ssttrriinngg ((@@)) - If the _s_h_o_w_-_m_o_d_e_-_i_n_-_p_r_o_m_p_t variable is enabled, this string is + If the _s_h_o_w_-_m_o_d_e_-_i_n_-_p_r_o_m_p_t variable is enabled, this string is displayed immediately before the last line of the primary prompt when emacs editing mode is active. The value is expanded like a - key binding, so the standard set of meta- and control- prefixes - and backslash escape sequences is available. The \1 and \2 es- - capes begin and end sequences of non-printing characters, which - can be used to embed a terminal control sequence into the mode + key binding, so the standard set of meta- and control- prefixes + and backslash escape sequences is available. The \1 and \2 es- + capes begin and end sequences of non-printing characters, which + can be used to embed a terminal control sequence into the mode string. eennaabbllee--aaccttiivvee--rreeggiioonn ((OOnn)) - When this variable is set to _O_n, rreeaaddlliinnee allows certain com- + When this variable is set to _O_n, rreeaaddlliinnee allows certain com- mands to designate the region as _a_c_t_i_v_e. When the region is ac- tive, rreeaaddlliinnee highlights the text in the region using the value of the aaccttiivvee--rreeggiioonn--ssttaarrtt--ccoolloorr variable, which defaults to the - string that enables the terminal's standout mode. The active + string that enables the terminal's standout mode. The active region shows the text inserted by bracketed-paste and any match- ing text found by incremental and non-incremental history searches. eennaabbllee--bbrraacckkeetteedd--ppaassttee ((OOnn)) - When set to OOnn, rreeaaddlliinnee configures the terminal to insert each - paste into the editing buffer as a single string of characters, - instead of treating each character as if it had been read from - the keyboard. This is called _b_r_a_c_k_e_t_e_d_-_p_a_s_t_e _m_o_d_e; it prevents - rreeaaddlliinnee from executing any editing commands bound to key se- + When set to OOnn, rreeaaddlliinnee configures the terminal to insert each + paste into the editing buffer as a single string of characters, + instead of treating each character as if it had been read from + the keyboard. This is called _b_r_a_c_k_e_t_e_d_-_p_a_s_t_e _m_o_d_e; it prevents + rreeaaddlliinnee from executing any editing commands bound to key se- quences appearing in the pasted text. eennaabbllee--kkeeyyppaadd ((OOffff)) When set to OOnn, rreeaaddlliinnee tries to enable the application keypad - when it is called. Some systems need this to enable the arrow + when it is called. Some systems need this to enable the arrow keys. eennaabbllee--mmeettaa--kkeeyy ((OOnn)) - When set to OOnn, rreeaaddlliinnee tries to enable any meta modifier key + When set to OOnn, rreeaaddlliinnee tries to enable any meta modifier key the terminal claims to support. On many terminals, the Meta key - is used to send eight-bit characters; this variable checks for - the terminal capability that indicates the terminal can enable - and disable a mode that sets the eighth bit of a character - (0200) if the Meta key is held down when the character is typed + is used to send eight-bit characters; this variable checks for + the terminal capability that indicates the terminal can enable + and disable a mode that sets the eighth bit of a character + (0200) if the Meta key is held down when the character is typed (a meta character). eexxppaanndd--ttiillddee ((OOffff)) If set to OOnn, rreeaaddlliinnee performs tilde expansion when it attempts word completion. ffoorrccee--mmeettaa--pprreeffiixx ((OOffff)) - If set to OOnn, rreeaaddlliinnee modifies its behavior when binding key - sequences containing \M- or Meta- (see KKeeyy BBiinnddiinnggss above) by + If set to OOnn, rreeaaddlliinnee modifies its behavior when binding key + sequences containing \M- or Meta- (see KKeeyy BBiinnddiinnggss above) by converting a key sequence of the form \M-_C or Meta-_C to the two- - character sequence EESSCC _C (adding the meta prefix). If + character sequence EESSCC _C (adding the meta prefix). If ffoorrccee--mmeettaa--pprreeffiixx is set to OOffff (the default), rreeaaddlliinnee uses the - value of the ccoonnvveerrtt--mmeettaa variable to determine whether to per- - form this conversion: if ccoonnvveerrtt--mmeettaa is OOnn, rreeaaddlliinnee performs - the conversion described above; if it is OOffff, rreeaaddlliinnee converts + value of the ccoonnvveerrtt--mmeettaa variable to determine whether to per- + form this conversion: if ccoonnvveerrtt--mmeettaa is OOnn, rreeaaddlliinnee performs + the conversion described above; if it is OOffff, rreeaaddlliinnee converts _C to a meta character by setting the eighth bit (0200). hhiissttoorryy--pprreesseerrvvee--ppooiinntt ((OOffff)) - If set to OOnn, the history code attempts to place point at the - same location on each history line retrieved with pprreevviioouuss--hhiiss-- + If set to OOnn, the history code attempts to place point at the + same location on each history line retrieved with pprreevviioouuss--hhiiss-- ttoorryy or nneexxtt--hhiissttoorryy. hhiissttoorryy--ssiizzee ((uunnsseett)) - Set the maximum number of history entries saved in the history - list. If set to zero, any existing history entries are deleted + Set the maximum number of history entries saved in the history + list. If set to zero, any existing history entries are deleted and no new entries are saved. If set to a value less than zero, - the number of history entries is not limited. By default, bbaasshh - sets the maximum number of history entries to the value of the - HHIISSTTSSIIZZEE shell variable. Setting _h_i_s_t_o_r_y_-_s_i_z_e to a non-numeric + the number of history entries is not limited. By default, bbaasshh + sets the maximum number of history entries to the value of the + HHIISSTTSSIIZZEE shell variable. Setting _h_i_s_t_o_r_y_-_s_i_z_e to a non-numeric value will set the maximum number of history entries to 500. hhoorriizzoonnttaall--ssccrroollll--mmooddee ((OOffff)) Setting this variable to OOnn makes rreeaaddlliinnee 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. This setting is automatically enabled + 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. This setting is automatically enabled for terminals of height 1. iinnppuutt--mmeettaa ((OOffff)) If set to OOnn, rreeaaddlliinnee enables eight-bit input (that is, it does not clear the eighth bit in the characters it reads), regardless of what the terminal claims it can support. The default is _O_f_f, - but rreeaaddlliinnee sets it to _O_n if the locale contains characters + but rreeaaddlliinnee sets it to _O_n if the locale contains characters whose encodings may include bytes with the eighth bit set. This - variable is dependent on the LLCC__CCTTYYPPEE locale category, and its + variable is dependent on the LLCC__CCTTYYPPEE locale category, and its value may change if the locale changes. The name mmeettaa--ffllaagg is a synonym for iinnppuutt--mmeettaa. iisseeaarrcchh--tteerrmmiinnaattoorrss (("CC--[[CC--jj")) - The string of characters that should terminate an incremental - search without subsequently executing the character as a com- - mand. If this variable has not been given a value, the charac- + The string of characters that should terminate an incremental + search without subsequently executing the character as a com- + mand. If this variable has not been given a value, the charac- ters _E_S_C and CC--jj terminate an incremental search. kkeeyymmaapp ((eemmaaccss)) - Set the current rreeaaddlliinnee keymap. The set of valid keymap names - is _e_m_a_c_s_, _e_m_a_c_s_-_s_t_a_n_d_a_r_d_, _e_m_a_c_s_-_m_e_t_a_, _e_m_a_c_s_-_c_t_l_x_, _v_i_, _v_i_-_c_o_m_- - _m_a_n_d, and _v_i_-_i_n_s_e_r_t. _v_i is equivalent to _v_i_-_c_o_m_m_a_n_d; _e_m_a_c_s is - equivalent to _e_m_a_c_s_-_s_t_a_n_d_a_r_d. The default value is _e_m_a_c_s; the + Set the current rreeaaddlliinnee keymap. The set of valid keymap names + is _e_m_a_c_s_, _e_m_a_c_s_-_s_t_a_n_d_a_r_d_, _e_m_a_c_s_-_m_e_t_a_, _e_m_a_c_s_-_c_t_l_x_, _v_i_, _v_i_-_c_o_m_- + _m_a_n_d, and _v_i_-_i_n_s_e_r_t. _v_i is equivalent to _v_i_-_c_o_m_m_a_n_d; _e_m_a_c_s is + equivalent to _e_m_a_c_s_-_s_t_a_n_d_a_r_d. The default value is _e_m_a_c_s; the value of eeddiittiinngg--mmooddee also affects the default keymap. kkeeyysseeqq--ttiimmeeoouutt ((550000)) - Specifies the duration rreeaaddlliinnee will wait for a character when - reading an ambiguous key sequence (one that can form a complete + Specifies the duration rreeaaddlliinnee will wait for a character when + reading an ambiguous key sequence (one that can form a complete key sequence using the input read so far, or can take additional - input to complete a longer key sequence). If rreeaaddlliinnee does not - receive any input within the timeout, it uses the shorter but - complete key sequence. The value is specified in milliseconds, - so a value of 1000 means that rreeaaddlliinnee will wait one second for - additional input. If this variable is set to a value less than - or equal to zero, or to a non-numeric value, rreeaaddlliinnee waits un- - til another key is pressed to decide which key sequence to com- + input to complete a longer key sequence). If rreeaaddlliinnee does not + receive any input within the timeout, it uses the shorter but + complete key sequence. The value is specified in milliseconds, + so a value of 1000 means that rreeaaddlliinnee will wait one second for + additional input. If this variable is set to a value less than + or equal to zero, or to a non-numeric value, rreeaaddlliinnee waits un- + til another key is pressed to decide which key sequence to com- plete. mmaarrkk--ddiirreeccttoorriieess ((OOnn)) If set to OOnn, completed directory names have a slash appended. mmaarrkk--mmooddiiffiieedd--lliinneess ((OOffff)) - If set to OOnn, rreeaaddlliinnee displays history lines that have been + If set to OOnn, rreeaaddlliinnee displays history lines that have been modified with a preceding asterisk (**). mmaarrkk--ssyymmlliinnkkeedd--ddiirreeccttoorriieess ((OOffff)) If set to OOnn, completed names which are symbolic links to direc- - tories have a slash appended, subject to the value of mmaarrkk--ddii-- + tories have a slash appended, subject to the value of mmaarrkk--ddii-- rreeccttoorriieess. mmaattcchh--hhiiddddeenn--ffiilleess ((OOnn)) - This variable, when set to OOnn, forces rreeaaddlliinnee to match files - whose names begin with a "." (hidden files) when performing - filename completion. If set to OOffff, the user must include the + This variable, when set to OOnn, forces rreeaaddlliinnee to match files + whose names begin with a "." (hidden files) when performing + filename completion. If set to OOffff, the user must include the leading "." in the filename to be completed. mmeennuu--ccoommpplleettee--ddiissppllaayy--pprreeffiixx ((OOffff)) - If set to OOnn, menu completion displays the common prefix of the + If set to OOnn, menu completion displays the common prefix of the list of possible completions (which may be empty) before cycling through the list. oouuttppuutt--mmeettaa ((OOffff)) - If set to OOnn, rreeaaddlliinnee displays characters with the eighth bit - set directly rather than as a meta-prefixed escape sequence. - The default is _O_f_f, but rreeaaddlliinnee sets it to _O_n if the locale - contains characters whose encodings may include bytes with the - eighth bit set. This variable is dependent on the LLCC__CCTTYYPPEE lo- + If set to OOnn, rreeaaddlliinnee displays characters with the eighth bit + set directly rather than as a meta-prefixed escape sequence. + The default is _O_f_f, but rreeaaddlliinnee sets it to _O_n if the locale + contains characters whose encodings may include bytes with the + eighth bit set. This variable is dependent on the LLCC__CCTTYYPPEE lo- cale category, and its value may change if the locale changes. ppaaggee--ccoommpplleettiioonnss ((OOnn)) If set to OOnn, rreeaaddlliinnee uses an internal pager resembling _m_o_r_e(1) @@ -3949,109 +3972,109 @@ RREEAADDLLIINNEE pprreeffeerr--vviissiibbllee--bbeellll See bbeellll--ssttyyllee. pprriinntt--ccoommpplleettiioonnss--hhoorriizzoonnttaallllyy ((OOffff)) - If set to OOnn, rreeaaddlliinnee displays completions with matches sorted + If set to OOnn, rreeaaddlliinnee displays completions with matches sorted horizontally in alphabetical order, rather than down the screen. rreevveerrtt--aallll--aatt--nneewwlliinnee ((OOffff)) - If set to OOnn, rreeaaddlliinnee will undo all changes to history lines - before returning when executing aacccceepptt--lliinnee. By default, his- - tory lines may be modified and retain individual undo lists + If set to OOnn, rreeaaddlliinnee will undo all changes to history lines + before returning when executing aacccceepptt--lliinnee. By default, his- + tory lines may be modified and retain individual undo lists across calls to rreeaaddlliinnee. sseeaarrcchh--iiggnnoorree--ccaassee ((OOffff)) - If set to OOnn, rreeaaddlliinnee performs incremental and non-incremental + If set to OOnn, rreeaaddlliinnee performs incremental and non-incremental history list searches in a case-insensitive fashion. sshhooww--aallll--iiff--aammbbiigguuoouuss ((OOffff)) - This alters the default behavior of the completion functions. + This alters the default behavior of the completion functions. If set to OOnn, words which have more than one possible completion - cause the matches to be listed immediately instead of ringing + cause the matches to be listed immediately instead of ringing the bell. sshhooww--aallll--iiff--uunnmmooddiiffiieedd ((OOffff)) - This alters the default behavior of the completion functions in + This alters the default behavior of the completion functions in a fashion similar to sshhooww--aallll--iiff--aammbbiigguuoouuss. If set to OOnn, words - which have more than one possible completion without any possi- - ble partial completion (the possible completions don't share a - common prefix) cause the matches to be listed immediately in- + which have more than one possible completion without any possi- + ble partial completion (the possible completions don't share a + common prefix) cause the matches to be listed immediately in- stead of ringing the bell. sshhooww--mmooddee--iinn--pprroommpptt ((OOffff)) - If set to OOnn, add a string to the beginning of the prompt indi- - cating the editing mode: emacs, vi command, or vi insertion. + If set to OOnn, add a string to the beginning of the prompt indi- + cating the editing mode: emacs, vi command, or vi insertion. The mode strings are user-settable (e.g., _e_m_a_c_s_-_m_o_d_e_-_s_t_r_i_n_g). sskkiipp--ccoommpplleetteedd--tteexxtt ((OOffff)) - If set to OOnn, 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, - rreeaaddlliinnee does not insert characters from the completion that - match characters after point in the word being completed, so + If set to OOnn, 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, + rreeaaddlliinnee 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. vvii--ccmmdd--mmooddee--ssttrriinngg ((((ccmmdd)))) - If the _s_h_o_w_-_m_o_d_e_-_i_n_-_p_r_o_m_p_t variable is enabled, this string is + If the _s_h_o_w_-_m_o_d_e_-_i_n_-_p_r_o_m_p_t variable is enabled, this string is displayed immediately before the last line of the primary prompt - when vi editing mode is active and in command mode. The value + when vi editing mode is active and in command mode. The value is expanded like a key binding, so the standard set of meta- and - control- prefixes and backslash escape sequences is available. - The \1 and \2 escapes begin and end sequences of non-printing - characters, which can be used to embed a terminal control se- + control- prefixes and backslash escape sequences is available. + The \1 and \2 escapes begin and end sequences of non-printing + characters, which can be used to embed a terminal control se- quence into the mode string. vvii--iinnss--mmooddee--ssttrriinngg ((((iinnss)))) - If the _s_h_o_w_-_m_o_d_e_-_i_n_-_p_r_o_m_p_t variable is enabled, this string is + If the _s_h_o_w_-_m_o_d_e_-_i_n_-_p_r_o_m_p_t variable is enabled, this string is displayed immediately before the last line of the primary prompt when vi editing mode is active and in insertion mode. The value is expanded like a key binding, so the standard set of meta- and - control- prefixes and backslash escape sequences is available. - The \1 and \2 escapes begin and end sequences of non-printing - characters, which can be used to embed a terminal control se- + control- prefixes and backslash escape sequences is available. + The \1 and \2 escapes begin and end sequences of non-printing + characters, which can be used to embed a terminal control se- quence into the mode string. vviissiibbllee--ssttaattss ((OOffff)) - If set to OOnn, a character denoting a file's type as reported by - _s_t_a_t(2) is appended to the filename when listing possible com- + If set to OOnn, a character denoting a file's type as reported by + _s_t_a_t(2) is appended to the filename when listing possible com- pletions. RReeaaddlliinnee CCoonnddiittiioonnaall CCoonnssttrruuccttss - RReeaaddlliinnee 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 + RReeaaddlliinnee 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 available. - $$iiff The $$iiff construct allows bindings to be made based on the edit- - ing mode, the terminal being used, or the application using - rreeaaddlliinnee. The text of the test, after any comparison operator, + $$iiff The $$iiff construct allows bindings to be made based on the edit- + ing mode, the terminal being used, or the application using + rreeaaddlliinnee. The text of the test, after any comparison operator, extends to the end of the line; unless otherwise noted, no char- acters are required to isolate it. - mmooddee The mmooddee== form of the $$iiff directive is used to test - whether rreeaaddlliinnee is in emacs or vi mode. This may be - used in conjunction with the sseett kkeeyymmaapp command, for in- - stance, to set bindings in the _e_m_a_c_s_-_s_t_a_n_d_a_r_d and - _e_m_a_c_s_-_c_t_l_x keymaps only if rreeaaddlliinnee is starting out in + mmooddee The mmooddee== form of the $$iiff directive is used to test + whether rreeaaddlliinnee is in emacs or vi mode. This may be + used in conjunction with the sseett kkeeyymmaapp command, for in- + stance, to set bindings in the _e_m_a_c_s_-_s_t_a_n_d_a_r_d and + _e_m_a_c_s_-_c_t_l_x keymaps only if rreeaaddlliinnee is starting out in emacs mode. - tteerrmm The tteerrmm== form may be used to include terminal-specific + tteerrmm The tteerrmm== form may be used to include terminal-specific key bindings, perhaps to bind the key sequences output by the terminal's function keys. The word on the right side of the == is tested against both the full name of the ter- - minal and the portion of the terminal name before the - first --. This allows _x_t_e_r_m to match both _x_t_e_r_m and + minal and the portion of the terminal name before the + first --. This allows _x_t_e_r_m to match both _x_t_e_r_m and _x_t_e_r_m_-_2_5_6_c_o_l_o_r, for instance. vveerrssiioonn - The vveerrssiioonn test may be used to perform comparisons - against specific rreeaaddlliinnee versions. The vveerrssiioonn expands - to the current rreeaaddlliinnee version. The set of comparison - operators includes ==, (and ====), !!==, <<==, >>==, <<, and >>. - The version number supplied on the right side of the op- - erator consists of a major version number, an optional + The vveerrssiioonn test may be used to perform comparisons + against specific rreeaaddlliinnee versions. The vveerrssiioonn expands + to the current rreeaaddlliinnee version. The set of comparison + operators includes ==, (and ====), !!==, <<==, >>==, <<, and >>. + The version number supplied on the right side of the op- + erator consists of a major version number, an optional decimal point, and an optional minor version (e.g., 77..11). - If the minor version is omitted, it defaults to 00. The - operator may be separated from the string vveerrssiioonn and + If the minor version is omitted, it defaults to 00. The + operator may be separated from the string vveerrssiioonn and from the version number argument by whitespace. _a_p_p_l_i_c_a_t_i_o_n The _a_p_p_l_i_c_a_t_i_o_n construct is used to include application- - specific settings. Each program using the rreeaaddlliinnee li- - brary sets the _a_p_p_l_i_c_a_t_i_o_n _n_a_m_e, and an initialization + specific settings. Each program using the rreeaaddlliinnee li- + brary sets the _a_p_p_l_i_c_a_t_i_o_n _n_a_m_e, 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 + 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 bbaasshh: $$iiff Bash @@ -4061,12 +4084,12 @@ RREEAADDLLIINNEE _v_a_r_i_a_b_l_e The _v_a_r_i_a_b_l_e construct provides simple equality tests for - rreeaaddlliinnee variables and values. The permitted comparison - operators are _=, _=_=, and _!_=. The variable name must be + rreeaaddlliinnee variables and values. The permitted comparison + operators are _=, _=_=, and _!_=. The variable name must be separated from the comparison operator by whitespace; the - operator may be separated from the value on the right - hand side by whitespace. String and boolean variables - may be tested. Boolean variables must be tested against + operator may be separated from the value on the right + hand side by whitespace. String and boolean variables + may be tested. Boolean variables must be tested against the values _o_n and _o_f_f. $$eellssee Commands in this branch of the $$iiff directive are executed if the @@ -4076,71 +4099,71 @@ RREEAADDLLIINNEE command. $$iinncclluuddee - This directive takes a single filename as an argument and reads + This directive takes a single filename as an argument and reads commands and key bindings from that file. For example, the fol- lowing directive would read _/_e_t_c_/_i_n_p_u_t_r_c: $$iinncclluuddee _/_e_t_c_/_i_n_p_u_t_r_c SSeeaarrcchhiinngg - RReeaaddlliinnee provides commands for searching through the command history + RReeaaddlliinnee provides commands for searching through the command history (see HHIISSTTOORRYY below) for lines containing a specified string. There are two search modes: _i_n_c_r_e_m_e_n_t_a_l and _n_o_n_-_i_n_c_r_e_m_e_n_t_a_l. - Incremental searches begin before the user has finished typing the - search string. As each character of the search string is typed, rreeaadd-- + Incremental searches begin before the user has finished typing the + search string. As each character of the search string is typed, rreeaadd-- lliinnee 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. When using emacs editing - mode, type CC--rr to search backward in the history for a particular - string. Typing CC--ss searches forward through the history. The charac- - ters present in the value of the iisseeaarrcchh--tteerrmmiinnaattoorrss variable are used - to terminate an incremental search. If that variable has not been as- - signed a value, _E_S_C and CC--jj terminate an incremental search. CC--gg - aborts an incremental search and restores the original line. When the - search is terminated, the history entry containing the search string + so far. An incremental search requires only as many characters as + needed to find the desired history entry. When using emacs editing + mode, type CC--rr to search backward in the history for a particular + string. Typing CC--ss searches forward through the history. The charac- + ters present in the value of the iisseeaarrcchh--tteerrmmiinnaattoorrss variable are used + to terminate an incremental search. If that variable has not been as- + signed a value, _E_S_C and CC--jj terminate an incremental search. CC--gg + aborts an incremental search and restores the original line. When the + search is terminated, the history entry containing the search string becomes the current line. - To find other matching entries in the history list, type CC--rr or CC--ss as - appropriate. This searches backward or forward in the history for the - next entry matching the search string typed so far. Any other key se- - quence bound to a rreeaaddlliinnee command terminates the search and executes - that command. For instance, a newline terminates the search and ac- + To find other matching entries in the history list, type CC--rr or CC--ss as + appropriate. This searches backward or forward in the history for the + next entry matching the search string typed so far. Any other key se- + quence bound to a rreeaaddlliinnee command terminates the search and executes + that command. For instance, a newline terminates the search and ac- cepts the line, thereby executing the command from the history list. A - movement command will terminate the search, make the last line found + movement command will terminate the search, make the last line found the current line, and begin editing. RReeaaddlliinnee remembers the last incremental search string. If two CC--rrs are - typed without any intervening characters defining a new search string, + typed without any intervening characters defining a new search string, rreeaaddlliinnee uses any remembered search string. - Non-incremental searches read the entire search string before starting + Non-incremental searches read the entire search string before starting to search for matching history entries. The search string may be typed by the user or be part of the contents of the current line. RReeaaddlliinnee CCoommmmaanndd NNaammeess - The following is a list of the names of the commands and the default + 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 accom- panying key sequence are unbound by default. In the following descriptions, _p_o_i_n_t refers to the current cursor posi- - tion, and _m_a_r_k refers to a cursor position saved by the sseett--mmaarrkk com- - mand. The text between the point and mark is referred to as the _r_e_- + tion, and _m_a_r_k refers to a cursor position saved by the sseett--mmaarrkk com- + mand. The text between the point and mark is referred to as the _r_e_- _g_i_o_n. RReeaaddlliinnee has the concept of an _a_c_t_i_v_e _r_e_g_i_o_n: when the region is active, rreeaaddlliinnee redisplay highlights the region using the value of the - aaccttiivvee--rreeggiioonn--ssttaarrtt--ccoolloorr variable. The eennaabbllee--aaccttiivvee--rreeggiioonn rreeaaddlliinnee + aaccttiivvee--rreeggiioonn--ssttaarrtt--ccoolloorr variable. The eennaabbllee--aaccttiivvee--rreeggiioonn rreeaaddlliinnee variable turns this on and off. Several commands set the region to ac- tive; those are noted below. CCoommmmaannddss ffoorr MMoovviinngg bbeeggiinnnniinngg--ooff--lliinnee ((CC--aa)) - Move to the start of the current line. This may also be bound + Move to the start of the current line. This may also be bound to the Home key on some keyboards. eenndd--ooff--lliinnee ((CC--ee)) - Move to the end of the line. This may also be bound to the End + Move to the end of the line. This may also be bound to the End key on some keyboards. ffoorrwwaarrdd--cchhaarr ((CC--ff)) - Move forward a character. This may also be bound to the right + Move forward a character. This may also be bound to the right arrow key on some keyboards. bbaacckkwwaarrdd--cchhaarr ((CC--bb)) Move back a character. This may also be bound to the left arrow @@ -4149,33 +4172,33 @@ RREEAADDLLIINNEE Move forward to the end of the next word. Words are composed of alphanumeric characters (letters and digits). bbaacckkwwaarrdd--wwoorrdd ((MM--bb)) - Move back to the start of the current or previous word. Words + Move back to the start of the current or previous word. Words are composed of alphanumeric characters (letters and digits). sshheellll--ffoorrwwaarrdd--wwoorrdd ((MM--CC--ff)) - Move forward to the end of the next word. Words are delimited + Move forward to the end of the next word. Words are delimited by non-quoted shell metacharacters. sshheellll--bbaacckkwwaarrdd--wwoorrdd ((MM--CC--bb)) - Move back to the start of the current or previous word. Words + Move back to the start of the current or previous word. Words are delimited by non-quoted shell metacharacters. pprreevviioouuss--ssccrreeeenn--lliinnee - Attempt to move point to the same physical screen column on the - previous physical screen line. This will not have the desired - effect if the current rreeaaddlliinnee line does not take up more than - one physical line or if point is not greater than the length of + Attempt to move point to the same physical screen column on the + previous physical screen line. This will not have the desired + effect if the current rreeaaddlliinnee line does not take up more than + one physical line or if point is not greater than the length of the prompt plus the screen width. nneexxtt--ssccrreeeenn--lliinnee - Attempt to move point to the same physical screen column on the - next physical screen line. This will not have the desired ef- + Attempt to move point to the same physical screen column on the + next physical screen line. This will not have the desired ef- fect if the current rreeaaddlliinnee line does not take up more than one - physical line or if the length of the current rreeaaddlliinnee line is + physical line or if the length of the current rreeaaddlliinnee line is not greater than the length of the prompt plus the screen width. cclleeaarr--ddiissppllaayy ((MM--CC--ll)) - Clear the screen and, if possible, the terminal's scrollback - buffer, then redraw the current line, leaving the current line + Clear the screen and, if possible, the terminal's scrollback + buffer, then redraw the current line, leaving the current line at the top of the screen. cclleeaarr--ssccrreeeenn ((CC--ll)) Clear the screen, then redraw the current line, leaving the cur- - rent line at the top of the screen. With a numeric argument, + rent line at the top of the screen. With a numeric argument, refresh the current line without clearing the screen. rreeddrraaww--ccuurrrreenntt--lliinnee Refresh the current line. @@ -4183,48 +4206,48 @@ RREEAADDLLIINNEE CCoommmmaannddss ffoorr MMaanniippuullaattiinngg tthhee HHiissttoorryy aacccceepptt--lliinnee ((NNeewwlliinnee,, RReettuurrnn)) 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 HHIISSTTCCOONNTTRROOLL and HHIISSTTIIGGNNOORREE variables. If the line is a - modified history line, restore the history line to its original + is non-empty, add it to the history list according to the state + of the HHIISSTTCCOONNTTRROOLL and HHIISSTTIIGGNNOORREE variables. If the line is a + modified history line, restore the history line to its original state. pprreevviioouuss--hhiissttoorryy ((CC--pp)) Fetch the previous command from the history list, moving back in - the list. This may also be bound to the up arrow key on some + the list. This may also be bound to the up arrow key on some keyboards. nneexxtt--hhiissttoorryy ((CC--nn)) - Fetch the next command from the history list, moving forward in - the list. This may also be bound to the down arrow key on some + Fetch the next command from the history list, moving forward in + the list. This may also be bound to the down arrow key on some keyboards. bbeeggiinnnniinngg--ooff--hhiissttoorryy ((MM--<<)) Move to the first line in the history. eenndd--ooff--hhiissttoorryy ((MM-->>)) - Move to the end of the input history, i.e., the line currently + Move to the end of the input history, i.e., the line currently being entered. ooppeerraattee--aanndd--ggeett--nneexxtt ((CC--oo)) - Accept the current line for execution as if a newline had been - entered, and fetch the next line relative to the current line - from the history for editing. A numeric argument, if supplied, + Accept the current line for execution as if a newline had been + entered, and fetch the next line relative to the current line + from the history for editing. A numeric argument, if supplied, specifies the history entry to use instead of the current line. ffeettcchh--hhiissttoorryy - With a numeric argument, fetch that entry from the history list + With a numeric argument, fetch that entry from the history list and make it the current line. Without an argument, move back to the first entry in the history list. rreevveerrssee--sseeaarrcchh--hhiissttoorryy ((CC--rr)) - Search backward starting at the current line and moving "up" - through the history as necessary. This is an incremental - search. This command sets the region to the matched text and - activates the region. - ffoorrwwaarrdd--sseeaarrcchh--hhiissttoorryy ((CC--ss)) - Search forward starting at the current line and moving "down" + Search backward starting at the current line and moving "up" through the history as necessary. This is an incremental search. This command sets the region to the matched text and activates the region. + ffoorrwwaarrdd--sseeaarrcchh--hhiissttoorryy ((CC--ss)) + Search forward starting at the current line and moving "down" + through the history as necessary. This is an incremental + search. This command sets the region to the matched text and + activates the region. nnoonn--iinnccrreemmeennttaall--rreevveerrssee--sseeaarrcchh--hhiissttoorryy ((MM--pp)) Search backward through the history starting at the current line - using a non-incremental search for a string supplied by the + using a non-incremental search for a string supplied by the user. The search string may match anywhere in a history line. nnoonn--iinnccrreemmeennttaall--ffoorrwwaarrdd--sseeaarrcchh--hhiissttoorryy ((MM--nn)) - Search forward through the history using a non-incremental + Search forward through the history using a non-incremental search for a string supplied by the user. The search string may match anywhere in a history line. hhiissttoorryy--sseeaarrcchh--bbaacckkwwaarrdd @@ -4234,72 +4257,72 @@ RREEAADDLLIINNEE non-incremental search. This may be bound to the Page Up key on some keyboards. hhiissttoorryy--sseeaarrcchh--ffoorrwwaarrdd - Search forward through the history for the string of characters + Search forward through the history for the string of characters between the start of the current line and the point. The search string must match at the beginning of a history line. This is a - non-incremental search. This may be bound to the Page Down key + non-incremental search. This may be bound to the Page Down key on some keyboards. hhiissttoorryy--ssuubbssttrriinngg--sseeaarrcchh--bbaacckkwwaarrdd Search backward through the history for the string of characters between the start of the current line and the point. The search - string may match anywhere in a history line. This is a non-in- + string may match anywhere in a history line. This is a non-in- cremental search. hhiissttoorryy--ssuubbssttrriinngg--sseeaarrcchh--ffoorrwwaarrdd - Search forward through the history for the string of characters + Search forward through the history for the string of characters between the start of the current line and the point. The search - string may match anywhere in a history line. This is a non-in- + string may match anywhere in a history line. This is a non-in- cremental search. yyaannkk--nntthh--aarrgg ((MM--CC--yy)) - Insert the first argument to the previous command (usually the + Insert the first argument to the previous command (usually the second word on the previous line) at point. With an argument _n, - insert the _nth word from the previous command (the words in the - previous command begin with word 0). A negative argument in- - serts the _nth word from the end of the previous command. Once - the argument _n is computed, this uses the history expansion fa- - cilities to extract the _nth word, as if the "!_n" history expan- + insert the _nth word from the previous command (the words in the + previous command begin with word 0). A negative argument in- + serts the _nth word from the end of the previous command. Once + the argument _n is computed, this uses the history expansion fa- + cilities to extract the _nth word, as if the "!_n" history expan- sion had been specified. yyaannkk--llaasstt--aarrgg ((MM--..,, MM--__)) - Insert the last argument to the previous command (the last word + Insert the last argument to the previous command (the last word of the previous history entry). With a numeric argument, behave - exactly like yyaannkk--nntthh--aarrgg. Successive calls to yyaannkk--llaasstt--aarrgg - move back through the history list, inserting the last word (or - the word specified by the argument to the first call) of each + exactly like yyaannkk--nntthh--aarrgg. Successive calls to yyaannkk--llaasstt--aarrgg + 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). This uses the history expansion facilities - to extract the last word, as if the "!$" history expansion had + calls determines the direction to move through the history. A + negative argument switches the direction through the history + (back or forward). This uses the history expansion facilities + to extract the last word, as if the "!$" history expansion had been specified. sshheellll--eexxppaanndd--lliinnee ((MM--CC--ee)) - Expand the line by performing shell word expansions. This per- + Expand the line by performing shell word expansions. This per- forms alias and history expansion, $$'_s_t_r_i_n_g' and $$"_s_t_r_i_n_g" quot- - ing, tilde expansion, parameter and variable expansion, arith- - metic expansion, command and process substitution, word split- - ting, and quote removal. An explicit argument suppresses com- - mand and process substitution. See HHIISSTTOORRYY EEXXPPAANNSSIIOONN below for + ing, tilde expansion, parameter and variable expansion, arith- + metic expansion, command and process substitution, word split- + ting, and quote removal. An explicit argument suppresses com- + mand and process substitution. See HHIISSTTOORRYY EEXXPPAANNSSIIOONN below for a description of history expansion. hhiissttoorryy--eexxppaanndd--lliinnee ((MM--^^)) - Perform history expansion on the current line. See HHIISSTTOORRYY EEXX-- + Perform history expansion on the current line. See HHIISSTTOORRYY EEXX-- PPAANNSSIIOONN below for a description of history expansion. mmaaggiicc--ssppaaccee - Perform history expansion on the current line and insert a + Perform history expansion on the current line and insert a space. See HHIISSTTOORRYY EEXXPPAANNSSIIOONN below for a description of history expansion. aalliiaass--eexxppaanndd--lliinnee - Perform alias expansion on the current line. See AALLIIAASSEESS above + Perform alias expansion on the current line. See AALLIIAASSEESS above for a description of alias expansion. hhiissttoorryy--aanndd--aalliiaass--eexxppaanndd--lliinnee Perform history and alias expansion on the current line. iinnsseerrtt--llaasstt--aarrgguummeenntt ((MM--..,, MM--__)) A synonym for yyaannkk--llaasstt--aarrgg. eeddiitt--aanndd--eexxeeccuuttee--ccoommmmaanndd ((CC--xx CC--ee)) - Invoke an editor on the current command line, and execute the + Invoke an editor on the current command line, and execute the result as shell commands. BBaasshh attempts to invoke $$VVIISSUUAALL, $$EEDD-- IITTOORR, and _e_m_a_c_s as the editor, in that order. CCoommmmaannddss ffoorr CChhaannggiinngg TTeexxtt _e_n_d_-_o_f_-_f_i_l_e ((uussuuaallllyy CC--dd)) - The character indicating end-of-file as set, for example, by + The character indicating end-of-file as set, for example, by _s_t_t_y(1). If this character is read when there are no characters on the line, and point is at the beginning of the line, rreeaaddlliinnee interprets it as the end of input and returns EEOOFF. @@ -4309,198 +4332,198 @@ RREEAADDLLIINNEE above for the effects. This may also be bound to the Delete key on some keyboards. bbaacckkwwaarrdd--ddeelleettee--cchhaarr ((RRuubboouutt)) - Delete the character behind the cursor. When given a numeric + Delete the character behind the cursor. When given a numeric argument, save the deleted text on the kill ring. ffoorrwwaarrdd--bbaacckkwwaarrdd--ddeelleettee--cchhaarr - Delete the character under the cursor, unless the cursor is at + Delete the character under the cursor, unless the cursor is at the end of the line, in which case the character behind the cur- sor is deleted. qquuootteedd--iinnsseerrtt ((CC--qq,, CC--vv)) - Add the next character typed to the line verbatim. This is how + Add the next character typed to the line verbatim. This is how to insert characters like CC--qq, for example. ttaabb--iinnsseerrtt ((CC--vv TTAABB)) Insert a tab character. sseellff--iinnsseerrtt ((aa,, bb,, AA,, 11,, !!,, ...)) Insert the character typed. bbrraacckkeetteedd--ppaassttee--bbeeggiinn - This function is intended to be bound to the "bracketed paste" - escape sequence sent by some terminals, and such a binding is - assigned by default. It allows rreeaaddlliinnee to insert the pasted - text as a single unit without treating each character as if it - had been read from the keyboard. The pasted characters are in- - serted as if each one was bound to sseellff--iinnsseerrtt instead of exe- + This function is intended to be bound to the "bracketed paste" + escape sequence sent by some terminals, and such a binding is + assigned by default. It allows rreeaaddlliinnee to insert the pasted + text as a single unit without treating each character as if it + had been read from the keyboard. The pasted characters are in- + serted as if each one was bound to sseellff--iinnsseerrtt instead of exe- cuting any editing commands. - Bracketed paste sets the region to the inserted text and acti- + Bracketed paste sets the region to the inserted text and acti- vates the region. ttrraannssppoossee--cchhaarrss ((CC--tt)) - 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. + 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. ttrraannssppoossee--wwoorrddss ((MM--tt)) - Drag the word before point past the word after point, moving - point past that word as well. If point is at the end of the + Drag the word before point past the word after point, moving + point past that word as well. If point is at the end of the line, this transposes the last two words on the line. sshheellll--ttrraannssppoossee--wwoorrddss ((MM--CC--tt)) - Drag the word before point past the word after point, moving - point past that word as well. If the insertion point is at the + Drag the word before point past the word after point, moving + point past that word as well. If the insertion point is at the end of the line, this transposes the last two words on the line. - Word boundaries are the same as sshheellll--ffoorrwwaarrdd--wwoorrdd and + Word boundaries are the same as sshheellll--ffoorrwwaarrdd--wwoorrdd and sshheellll--bbaacckkwwaarrdd--wwoorrdd. uuppccaassee--wwoorrdd ((MM--uu)) - Uppercase the current (or following) word. With a negative ar- + Uppercase the current (or following) word. With a negative ar- gument, uppercase the previous word, but do not move point. ddoowwnnccaassee--wwoorrdd ((MM--ll)) - Lowercase the current (or following) word. With a negative ar- + Lowercase the current (or following) word. With a negative ar- gument, lowercase the previous word, but do not move point. ccaappiittaalliizzee--wwoorrdd ((MM--cc)) Capitalize the current (or following) word. With a negative ar- gument, capitalize the previous word, but do not move point. oovveerrwwrriittee--mmooddee - Toggle overwrite mode. With an explicit positive numeric argu- + Toggle overwrite mode. With an explicit positive numeric argu- ment, switches to overwrite mode. With an explicit non-positive numeric argument, switches to insert mode. This command affects - only eemmaaccss mode; vvii mode does overwrite differently. Each call + only eemmaaccss mode; vvii mode does overwrite differently. Each call to _r_e_a_d_l_i_n_e_(_) starts in insert mode. - In overwrite mode, characters bound to sseellff--iinnsseerrtt replace the - text at point rather than pushing the text to the right. Char- - acters bound to bbaacckkwwaarrdd--ddeelleettee--cchhaarr replace the character be- - fore point with a space. By default, this command is unbound, + In overwrite mode, characters bound to sseellff--iinnsseerrtt replace the + text at point rather than pushing the text to the right. Char- + acters bound to bbaacckkwwaarrdd--ddeelleettee--cchhaarr replace the character be- + fore point with a space. By default, this command is unbound, but may be bound to the Insert key on some keyboards. KKiilllliinngg aanndd YYaannkkiinngg kkiillll--lliinnee ((CC--kk)) Kill the text from point to the end of the current line. With a - negative numeric argument, kill backward from the cursor to the + negative numeric argument, kill backward from the cursor to the beginning of the line. bbaacckkwwaarrdd--kkiillll--lliinnee ((CC--xx RRuubboouutt)) Kill backward to the beginning of the current line. With a neg- - ative numeric argument, kill forward from the cursor to the end + ative numeric argument, kill forward from the cursor to the end of the line. uunniixx--lliinnee--ddiissccaarrdd ((CC--uu)) - Kill backward from point to the beginning of the line, saving + Kill backward from point to the beginning of the line, saving the killed text on the kill-ring. kkiillll--wwhhoollee--lliinnee - Kill all characters on the current line, no matter where point + Kill all characters on the current line, no matter where point is. kkiillll--wwoorrdd ((MM--dd)) - 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 + 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 ffoorrwwaarrdd--wwoorrdd. bbaacckkwwaarrdd--kkiillll--wwoorrdd ((MM--RRuubboouutt)) - Kill the word behind point. Word boundaries are the same as + Kill the word behind point. Word boundaries are the same as those used by bbaacckkwwaarrdd--wwoorrdd. sshheellll--kkiillll--wwoorrdd ((MM--CC--dd)) - 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 + 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 sshheellll--ffoorrwwaarrdd--wwoorrdd. sshheellll--bbaacckkwwaarrdd--kkiillll--wwoorrdd - Kill the word behind point. Word boundaries are the same as + Kill the word behind point. Word boundaries are the same as those used by sshheellll--bbaacckkwwaarrdd--wwoorrdd. uunniixx--wwoorrdd--rruubboouutt ((CC--ww)) - Kill the word behind point, using white space as a word bound- + Kill the word behind point, using white space as a word bound- ary, saving the killed text on the kill-ring. uunniixx--ffiilleennaammee--rruubboouutt - Kill the word behind point, using white space and the slash - character as the word boundaries, saving the killed text on the + Kill the word behind point, using white space and the slash + character as the word boundaries, saving the killed text on the kill-ring. ddeelleettee--hhoorriizzoonnttaall--ssppaaccee ((MM--\\)) Delete all spaces and tabs around point. kkiillll--rreeggiioonn Kill the text in the current region. ccooppyy--rreeggiioonn--aass--kkiillll - Copy the text in the region to the kill buffer, so it can be + Copy the text in the region to the kill buffer, so it can be yanked immediately. ccooppyy--bbaacckkwwaarrdd--wwoorrdd - Copy the word before point to the kill buffer. The word bound- + Copy the word before point to the kill buffer. The word bound- aries are the same as bbaacckkwwaarrdd--wwoorrdd. ccooppyy--ffoorrwwaarrdd--wwoorrdd - Copy the word following point to the kill buffer. The word + Copy the word following point to the kill buffer. The word boundaries are the same as ffoorrwwaarrdd--wwoorrdd. yyaannkk ((CC--yy)) Yank the top of the kill ring into the buffer at point. yyaannkk--ppoopp ((MM--yy)) - Rotate the kill ring, and yank the new top. Only works follow- + Rotate the kill ring, and yank the new top. Only works follow- ing yyaannkk or yyaannkk--ppoopp. NNuummeerriicc AArrgguummeennttss ddiiggiitt--aarrgguummeenntt ((MM--00,, MM--11,, ...,, MM----)) - Add this digit to the argument already accumulating, or start a + Add this digit to the argument already accumulating, or start a new argument. M-- starts a negative argument. uunniivveerrssaall--aarrgguummeenntt - 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 fol- + 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 fol- lowed by digits, executing uunniivveerrssaall--aarrgguummeenntt again ends the nu- meric argument, but is otherwise ignored. As a special case, if this command is immediately followed by a character that is nei- - ther a digit nor 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 argu- + ther a digit nor 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 argu- ment count four, a second time makes the argument count sixteen, and so on. CCoommpplleettiinngg ccoommpplleettee ((TTAABB)) - Attempt to perform completion on the text before point. BBaasshh - attempts completion by first checking for any programmable com- - pletions for the command word (see PPrrooggrraammmmaabbllee CCoommpplleettiioonn be- + Attempt to perform completion on the text before point. BBaasshh + attempts completion by first checking for any programmable com- + pletions for the command word (see PPrrooggrraammmmaabbllee CCoommpplleettiioonn be- low), otherwise treating the text as a variable (if the text be- gins with $$), username (if the text begins with ~~), hostname (if - the text begins with @@), or command (including aliases, func- - tions, and builtins) in turn. If none of these produces a + the text begins with @@), or command (including aliases, func- + tions, and builtins) in turn. If none of these produces a match, it falls back to filename completion. ppoossssiibbllee--ccoommpplleettiioonnss ((MM--??)) - List the possible completions of the text before point. When + List the possible completions of the text before point. When displaying completions, rreeaaddlliinnee sets the number of columns used - for display to the value of ccoommpplleettiioonn--ddiissppllaayy--wwiiddtthh, the value - of the shell variable CCOOLLUUMMNNSS, or the screen width, in that or- + for display to the value of ccoommpplleettiioonn--ddiissppllaayy--wwiiddtthh, the value + of the shell variable CCOOLLUUMMNNSS, or the screen width, in that or- der. iinnsseerrtt--ccoommpplleettiioonnss ((MM--**)) - Insert all completions of the text before point that would have + Insert all completions of the text before point that would have been generated by ppoossssiibbllee--ccoommpplleettiioonnss, separated by a space. mmeennuu--ccoommpplleettee - Similar to ccoommpplleettee, but replaces the word to be completed with - a single match from the list of possible completions. Repeat- - edly executing mmeennuu--ccoommpplleettee steps through the list of possible - completions, inserting each match in turn. At the end of the - list of completions, mmeennuu--ccoommpplleettee rings the bell (subject to - the setting of bbeellll--ssttyyllee) and restores the original text. An - argument of _n moves _n positions forward in the list of matches; - a negative argument moves backward through the list. This com- + Similar to ccoommpplleettee, but replaces the word to be completed with + a single match from the list of possible completions. Repeat- + edly executing mmeennuu--ccoommpplleettee steps through the list of possible + completions, inserting each match in turn. At the end of the + list of completions, mmeennuu--ccoommpplleettee rings the bell (subject to + the setting of bbeellll--ssttyyllee) and restores the original text. An + argument of _n moves _n positions forward in the list of matches; + a negative argument moves backward through the list. This com- mand is intended to be bound to TTAABB, but is unbound by default. mmeennuu--ccoommpplleettee--bbaacckkwwaarrdd - Identical to mmeennuu--ccoommpplleettee, but moves backward through the list - of possible completions, as if mmeennuu--ccoommpplleettee had been given a + Identical to mmeennuu--ccoommpplleettee, but moves backward through the list + of possible completions, as if mmeennuu--ccoommpplleettee had been given a negative argument. This command is unbound by default. eexxppoorrtt--ccoommpplleettiioonnss - Perform completion on the word before point as described above - and write the list of possible completions to rreeaaddlliinnee's output - stream using the following format, writing information on sepa- + Perform completion on the word before point as described above + and write the list of possible completions to rreeaaddlliinnee's output + stream using the following format, writing information on sepa- rate lines: +o the number of matches _N; +o the word being completed; - +o _S:_E, where _S and _E are the start and end offsets of the + +o _S:_E, where _S and _E are the start and end offsets of the word in the rreeaaddlliinnee line buffer; then +o each match, one per line - If there are no matches, the first line will be "0", and this - command does not print any output after the _S:_E. If there is - only a single match, this prints a single line containing it. - If there is more than one match, this prints the common prefix - of the matches, which may be empty, on the first line after the + If there are no matches, the first line will be "0", and this + command does not print any output after the _S:_E. If there is + only a single match, this prints a single line containing it. + If there is more than one match, this prints the common prefix + of the matches, which may be empty, on the first line after the _S:_E, then the matches on subsequent lines. In this case, _N will include the first line with the common prefix. The user or application should be able to accommodate the possi- bility of a blank line. The intent is that the user or applica- - tion reads _N lines after the line containing _S:_E to obtain the + tion reads _N lines after the line containing _S:_E to obtain the match list. This command is unbound by default. ddeelleettee--cchhaarr--oorr--lliisstt - Deletes the character under the cursor if not at the beginning - or end of the line (like ddeelleettee--cchhaarr). At the end of the line, + Deletes the character under the cursor if not at the beginning + or end of the line (like ddeelleettee--cchhaarr). At the end of the line, it behaves identically to ppoossssiibbllee--ccoommpplleettiioonnss. This command is unbound by default. @@ -4512,7 +4535,7 @@ RREEAADDLLIINNEE it as a filename. ccoommpplleettee--uusseerrnnaammee ((MM--~~)) - Attempt completion on the text before point, treating it as a + Attempt completion on the text before point, treating it as a username. ppoossssiibbllee--uusseerrnnaammee--ccoommpplleettiioonnss ((CC--xx ~~)) @@ -4520,7 +4543,7 @@ RREEAADDLLIINNEE it as a username. ccoommpplleettee--vvaarriiaabbllee ((MM--$$)) - Attempt completion on the text before point, treating it as a + Attempt completion on the text before point, treating it as a shell variable. ppoossssiibbllee--vvaarriiaabbllee--ccoommpplleettiioonnss ((CC--xx $$)) @@ -4528,7 +4551,7 @@ RREEAADDLLIINNEE it as a shell variable. ccoommpplleettee--hhoossttnnaammee ((MM--@@)) - Attempt completion on the text before point, treating it as a + Attempt completion on the text before point, treating it as a hostname. ppoossssiibbllee--hhoossttnnaammee--ccoommpplleettiioonnss ((CC--xx @@)) @@ -4536,9 +4559,9 @@ RREEAADDLLIINNEE it as a hostname. ccoommpplleettee--ccoommmmaanndd ((MM--!!)) - 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 + 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. ppoossssiibbllee--ccoommmmaanndd--ccoommpplleettiioonnss ((CC--xx !!)) @@ -4546,42 +4569,42 @@ RREEAADDLLIINNEE it as a command name. ddyynnaammiicc--ccoommpplleettee--hhiissttoorryy ((MM--TTAABB)) - Attempt completion on the text before point, comparing the text + Attempt completion on the text before point, comparing the text against history list entries for possible completion matches. ddaabbbbrreevv--eexxppaanndd - Attempt menu completion on the text before point, comparing the + Attempt menu completion on the text before point, comparing the text against lines from the history list for possible completion matches. ccoommpplleettee--iinnttoo--bbrraacceess ((MM--{{)) Perform filename completion and insert the list of possible com- - pletions enclosed within braces so the list is available to the + pletions enclosed within braces so the list is available to the shell (see BBrraaccee EExxppaannssiioonn above). KKeeyybbooaarrdd MMaaccrrooss ssttaarrtt--kkbbdd--mmaaccrroo ((CC--xx (()) - Begin saving the characters typed into the current keyboard + Begin saving the characters typed into the current keyboard macro. eenndd--kkbbdd--mmaaccrroo ((CC--xx )))) Stop saving the characters typed into the current keyboard macro and store the definition. ccaallll--llaasstt--kkbbdd--mmaaccrroo ((CC--xx ee)) - Re-execute the last keyboard macro defined, by making the char- + Re-execute the last keyboard macro defined, by making the char- acters in the macro appear as if typed at the keyboard. pprriinntt--llaasstt--kkbbdd--mmaaccrroo (()) - Print the last keyboard macro defined in a format suitable for + Print the last keyboard macro defined in a format suitable for the _i_n_p_u_t_r_c file. MMiisscceellllaanneeoouuss rree--rreeaadd--iinniitt--ffiillee ((CC--xx CC--rr)) - Read in the contents of the _i_n_p_u_t_r_c file, and incorporate any + Read in the contents of the _i_n_p_u_t_r_c file, and incorporate any bindings or variable assignments found there. aabboorrtt ((CC--gg)) - Abort the current editing command and ring the terminal's bell + Abort the current editing command and ring the terminal's bell (subject to the setting of bbeellll--ssttyyllee). ddoo--lloowweerrccaassee--vveerrssiioonn ((MM--AA,, MM--BB,, MM--_x,, ...)) - If the metafied character _x is uppercase, run the command that + If the metafied character _x is uppercase, run the command that is bound to the corresponding metafied lowercase character. The behavior is undefined if _x is already lowercase. pprreeffiixx--mmeettaa ((EESSCC)) @@ -4589,239 +4612,239 @@ RREEAADDLLIINNEE uunnddoo ((CC--__,, CC--xx CC--uu)) Incremental undo, separately remembered for each line. rreevveerrtt--lliinnee ((MM--rr)) - Undo all changes made to this line. This is like executing the - uunnddoo command enough times to return the line to its initial + Undo all changes made to this line. This is like executing the + uunnddoo command enough times to return the line to its initial state. ttiillddee--eexxppaanndd ((MM--&&)) Perform tilde expansion on the current word. sseett--mmaarrkk ((CC--@@,, MM--<>)) - Set the mark to the point. If a numeric argument is supplied, + Set the mark to the point. If a numeric argument is supplied, set the mark to that position. eexxcchhaannggee--ppooiinntt--aanndd--mmaarrkk ((CC--xx CC--xx)) - Swap the point with the mark. Set the current cursor position + Swap the point with the mark. Set the current cursor position to the saved position, then set the mark to the old cursor posi- tion. cchhaarraacctteerr--sseeaarrcchh ((CC--]])) - Read a character and move point to the next occurrence of that - character. A negative argument searches for previous occur- + Read a character and move point to the next occurrence of that + character. A negative argument searches for previous occur- rences. cchhaarraacctteerr--sseeaarrcchh--bbaacckkwwaarrdd ((MM--CC--]])) - Read a character and move point to the previous occurrence of + Read a character and move point to the previous occurrence of that character. A negative argument searches for subsequent oc- currences. sskkiipp--ccssii--sseeqquueennccee - Read enough characters to consume a multi-key sequence such as - those defined for keys like Home and End. CSI sequences begin + Read enough characters to consume a multi-key sequence such as + those defined for keys like Home and End. CSI sequences begin with a Control Sequence Indicator (CSI), usually _E_S_C _[. If this sequence is bound to "\e[", keys producing CSI sequences have no effect unless explicitly bound to a rreeaaddlliinnee command, instead of inserting stray characters into the editing buffer. This is un- bound by default, but usually bound to _E_S_C _[. iinnsseerrtt--ccoommmmeenntt ((MM--##)) - Without a numeric argument, insert the value of the rreeaaddlliinnee + Without a numeric argument, insert the value of the rreeaaddlliinnee ccoommmmeenntt--bbeeggiinn variable 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 ccoommmmeenntt--bbeeggiinn, insert the value; otherwise delete the - characters in ccoommmmeenntt--bbeeggiinn from the beginning of the line. In - either case, the line is accepted as if a newline had been - typed. The default value of ccoommmmeenntt--bbeeggiinn causes this command + 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 ccoommmmeenntt--bbeeggiinn, insert the value; otherwise delete the + characters in ccoommmmeenntt--bbeeggiinn from the beginning of the line. In + either case, the line is accepted as if a newline had been + typed. The default value of ccoommmmeenntt--bbeeggiinn 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 ex- ecuted by the shell. ssppeellll--ccoorrrreecctt--wwoorrdd ((CC--xx ss)) - Perform spelling correction on the current word, treating it as - a directory or filename, in the same way as the ccddssppeellll shell - option. Word boundaries are the same as those used by + Perform spelling correction on the current word, treating it as + a directory or filename, in the same way as the ccddssppeellll shell + option. Word boundaries are the same as those used by sshheellll--ffoorrwwaarrdd--wwoorrdd. gglloobb--ccoommpplleettee--wwoorrdd ((MM--gg)) Treat the word before point as a pattern for pathname expansion, - with an asterisk implicitly appended, then use the pattern to + with an asterisk implicitly appended, then use the pattern to generate a list of matching file names for possible completions. gglloobb--eexxppaanndd--wwoorrdd ((CC--xx **)) Treat the word before point as a pattern for pathname expansion, - and insert the list of matching file names, replacing the word. - If a numeric argument is supplied, append a ** before pathname + and insert the list of matching file names, replacing the word. + If a numeric argument is supplied, append a ** before pathname expansion. gglloobb--lliisstt--eexxppaannssiioonnss ((CC--xx gg)) Display the list of expansions that would have been generated by - gglloobb--eexxppaanndd--wwoorrdd and redisplay the line. If a numeric argument + gglloobb--eexxppaanndd--wwoorrdd and redisplay the line. If a numeric argument is supplied, append a ** before pathname expansion. dduummpp--ffuunnccttiioonnss - Print all of the functions and their key bindings to the rreeaadd-- + Print all of the functions and their key bindings to the rreeaadd-- lliinnee output stream. If a numeric argument is supplied, the out- - put is formatted in such a way that it can be made part of an + put is formatted in such a way that it can be made part of an _i_n_p_u_t_r_c file. dduummpp--vvaarriiaabblleess Print all of the settable rreeaaddlliinnee variables and their values to - the rreeaaddlliinnee output stream. If a numeric argument is supplied, - the output is formatted in such a way that it can be made part + the rreeaaddlliinnee output stream. If a numeric argument is supplied, + the output is formatted in such a way that it can be made part of an _i_n_p_u_t_r_c file. dduummpp--mmaaccrrooss - Print all of the rreeaaddlliinnee key sequences bound to macros and the + Print all of the rreeaaddlliinnee key sequences bound to macros and the strings they output to the rreeaaddlliinnee output stream. If a numeric argument is supplied, the output is formatted in such a way that it can be made part of an _i_n_p_u_t_r_c file. eexxeeccuuttee--nnaammeedd--ccoommmmaanndd ((MM--xx)) Read a bindable rreeaaddlliinnee command name from the input and execute - the function to which it's bound, as if the key sequence to - which it was bound appeared in the input. If this function is + the function to which it's bound, as if the key sequence to + which it was bound appeared in the input. If this function is supplied with a numeric argument, it passes that argument to the function it executes. ddiissppllaayy--sshheellll--vveerrssiioonn ((CC--xx CC--vv)) Display version information about the current instance of bbaasshh. PPrrooggrraammmmaabbllee CCoommpplleettiioonn - When a user attempts word completion for a command or an argument to a - command for which a completion specification (a _c_o_m_p_s_p_e_c) has been de- - fined using the ccoommpplleettee builtin (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below), + When a user attempts word completion for a command or an argument to a + command for which a completion specification (a _c_o_m_p_s_p_e_c) has been de- + fined using the ccoommpplleettee builtin (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below), rreeaaddlliinnee invokes the programmable completion facilities. - First, bbaasshh identifies the command name. If a compspec has been de- - fined for that command, the compspec is used to generate the list of - possible completions for the word. If the command word is the empty - string (completion attempted at the beginning of an empty line), bbaasshh - uses any compspec defined with the --EE option to ccoommpplleettee. The --II op- - tion to ccoommpplleettee indicates that the command word is the first non-as- + First, bbaasshh identifies the command name. If a compspec has been de- + fined for that command, the compspec is used to generate the list of + possible completions for the word. If the command word is the empty + string (completion attempted at the beginning of an empty line), bbaasshh + uses any compspec defined with the --EE option to ccoommpplleettee. The --II op- + tion to ccoommpplleettee indicates that the command word is the first non-as- signment word on the line, or after a command delimiter such as ;; or ||. This usually indicates command name completion. - If the command word is a full pathname, bbaasshh searches for a compspec - for the full pathname first. If there is no compspec for the full - pathname, bbaasshh attempts to find a compspec for the portion following - the final slash. If those searches do not result in a compspec, or if - there is no compspec for the command word, bbaasshh uses any compspec de- - fined with the --DD option to ccoommpplleettee as the default. If there is no - default compspec, bbaasshh performs alias expansion on the command word as - a final resort, and attempts to find a compspec for the command word + If the command word is a full pathname, bbaasshh searches for a compspec + for the full pathname first. If there is no compspec for the full + pathname, bbaasshh attempts to find a compspec for the portion following + the final slash. If those searches do not result in a compspec, or if + there is no compspec for the command word, bbaasshh uses any compspec de- + fined with the --DD option to ccoommpplleettee as the default. If there is no + default compspec, bbaasshh performs alias expansion on the command word as + a final resort, and attempts to find a compspec for the command word resulting from any successful expansion. If a compspec is not found, bbaasshh performs its default completion as de- - scribed above under CCoommpplleettiinngg. Otherwise, once a compspec has been + scribed above under CCoommpplleettiinngg. Otherwise, once a compspec has been found, bbaasshh uses it to generate the list of matching words. - First, bbaasshh performs the _a_c_t_i_o_n_s specified by the compspec. This only - returns matches which are prefixes of the word being completed. When - the --ff or --dd option is used for filename or directory name completion, + First, bbaasshh performs the _a_c_t_i_o_n_s specified by the compspec. This only + returns matches which are prefixes of the word being completed. When + the --ff or --dd option is used for filename or directory name completion, bbaasshh uses the shell variable FFIIGGNNOORREE to filter the matches. Next, programmable completion generates matches specified by a pathname - expansion pattern supplied as an argument to the --GG option. The words + expansion pattern supplied as an argument to the --GG option. The words generated by the pattern need not match the word being completed. BBaasshh - uses the FFIIGGNNOORREE variable to filter the matches, but does not use the + uses the FFIIGGNNOORREE variable to filter the matches, but does not use the GGLLOOBBIIGGNNOORREE shell variable. - Next, completion considers the string specified as the argument to the - --WW option. The string is first split using the characters in the IIFFSS - special variable as delimiters. This honors shell quoting within the - string, in order to provide a mechanism for the words to contain shell - metacharacters or characters in the value of IIFFSS. Each word is then + Next, completion considers the string specified as the argument to the + --WW option. The string is first split using the characters in the IIFFSS + special variable as delimiters. This honors shell quoting within the + string, in order to provide a mechanism for the words to contain shell + metacharacters or characters in the value of IIFFSS. Each word is then expanded using brace expansion, tilde expansion, parameter and variable expansion, command substitution, and arithmetic expansion, as described above under EEXXPPAANNSSIIOONN. The results are split using the rules described - above under WWoorrdd SSpplliittttiinngg. The results of the expansion are prefix- + above under WWoorrdd SSpplliittttiinngg. The results of the expansion are prefix- matched against the word being completed, and the matching words become possible completions. - After these matches have been generated, bbaasshh executes any shell func- + After these matches have been generated, bbaasshh executes any shell func- tion or command specified with the --FF and --CC options. When the command - or function is invoked, bbaasshh assigns values to the CCOOMMPP__LLIINNEE, - CCOOMMPP__PPOOIINNTT, CCOOMMPP__KKEEYY, and CCOOMMPP__TTYYPPEE variables as described above under - SShheellll VVaarriiaabblleess. If a shell function is being invoked, bbaasshh also sets - the CCOOMMPP__WWOORRDDSS and CCOOMMPP__CCWWOORRDD variables. When the function or command - is invoked, the first argument ($$11) is the name of the command whose + or function is invoked, bbaasshh assigns values to the CCOOMMPP__LLIINNEE, + CCOOMMPP__PPOOIINNTT, CCOOMMPP__KKEEYY, and CCOOMMPP__TTYYPPEE variables as described above under + SShheellll VVaarriiaabblleess. If a shell function is being invoked, bbaasshh also sets + the CCOOMMPP__WWOORRDDSS and CCOOMMPP__CCWWOORRDD variables. When the function or command + is invoked, the first argument ($$11) is the name of the command whose arguments are being completed, the second argument ($$22) is the word be- - ing completed, and the third argument ($$33) is the word preceding the - word being completed on the current command line. There is no filter- - ing of the generated completions against the word being completed; the - function or command has complete freedom in generating the matches and + ing completed, and the third argument ($$33) is the word preceding the + word being completed on the current command line. There is no filter- + ing of the generated completions against the word being completed; the + function or command has complete freedom in generating the matches and they do not need to match a prefix of the word. - Any function specified with --FF is invoked first. The function may use + Any function specified with --FF is invoked first. The function may use any of the shell facilities, including the ccoommppggeenn and ccoommppoopptt builtins - described below, to generate the matches. It must put the possible + described below, to generate the matches. It must put the possible completions in the CCOOMMPPRREEPPLLYY array variable, one per array element. - Next, any command specified with the --CC option is invoked in an envi- - ronment equivalent to command substitution. It should print a list of - completions, one per line, to the standard output. Backslash will es- - cape a newline, if necessary. These are added to the set of possible + Next, any command specified with the --CC option is invoked in an envi- + ronment equivalent to command substitution. It should print a list of + completions, one per line, to the standard output. Backslash will es- + cape a newline, if necessary. These are added to the set of possible completions. - External commands that are invoked to generate completions ( "external + External commands that are invoked to generate completions ( "external completers") receive the word preceding the completion word as an argu- ment, as described above. This provides context that is sometimes use- - ful, but may include information that is considered sensitive or part - of a word expansion that will not appear in the command line after ex- - pansion. That word may be visible in process listings or in audit - logs. This may be a concern to users and completion specification au- - thors if there is sensitive information on the command line before ex- - pansion, since completion takes place before words are expanded. If - this is an issue, completion authors should use functions as wrappers - around external commands and pass context information to the external + ful, but may include information that is considered sensitive or part + of a word expansion that will not appear in the command line after ex- + pansion. That word may be visible in process listings or in audit + logs. This may be a concern to users and completion specification au- + thors if there is sensitive information on the command line before ex- + pansion, since completion takes place before words are expanded. If + this is an issue, completion authors should use functions as wrappers + around external commands and pass context information to the external command in a different way. External completers can infer context from - the CCOOMMPP__LLIINNEE and CCOOMMPP__PPOOIINNTT environment variables, but they need to - ensure they break words in the same way rreeaaddlliinnee does, using the + the CCOOMMPP__LLIINNEE and CCOOMMPP__PPOOIINNTT environment variables, but they need to + ensure they break words in the same way rreeaaddlliinnee does, using the CCOOMMPP__WWOORRDDBBRREEAAKKSS variable. After generating all of the possible completions, bbaasshh applies any fil- - ter specified with the --XX option to the completions in the list. The - filter is a pattern as used for pathname expansion; a && in the pattern + ter specified with the --XX option to the completions in the list. The + filter is a pattern as used for pathname expansion; a && in the pattern is replaced with the text of the word being completed. A literal && may be escaped with a backslash; the backslash is removed before attempting - a match. Any completion that matches the pattern is removed from the - list. A leading !! negates the pattern; in this case bbaasshh removes any - completion that does not match the pattern. If the nnooccaasseemmaattcchh shell - option is enabled, bbaasshh performs the match without regard to the case + a match. Any completion that matches the pattern is removed from the + list. A leading !! negates the pattern; in this case bbaasshh removes any + completion that does not match the pattern. If the nnooccaasseemmaattcchh shell + option is enabled, bbaasshh performs the match without regard to the case of alphabetic characters. - Finally, programmable completion adds any prefix and suffix specified - with the --PP and --SS options, respectively, to each completion, and re- + Finally, programmable completion adds any prefix and suffix specified + with the --PP and --SS options, respectively, to each completion, and re- turns the result to rreeaaddlliinnee as the list of possible completions. - If the previously-applied actions do not generate any matches, and the - --oo ddiirrnnaammeess option was supplied to ccoommpplleettee when the compspec was de- + If the previously-applied actions do not generate any matches, and the + --oo ddiirrnnaammeess option was supplied to ccoommpplleettee when the compspec was de- fined, bbaasshh attempts directory name completion. - If the --oo pplluussddiirrss option was supplied to ccoommpplleettee when the compspec - was defined, bbaasshh attempts directory name completion and adds any + If the --oo pplluussddiirrss option was supplied to ccoommpplleettee when the compspec + was defined, bbaasshh attempts directory name completion and adds any matches to the set of possible completions. - 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 bbaasshh completions and the rreeaaddlliinnee default of filename comple- - tion are disabled. If the --oo bbaasshhddeeffaauulltt option was supplied to ccoomm-- - pplleettee when the compspec was defined, and the compspec generates no - matches, bbaasshh attempts its default completions. If the compspec and, + 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 bbaasshh completions and the rreeaaddlliinnee default of filename comple- + tion are disabled. If the --oo bbaasshhddeeffaauulltt option was supplied to ccoomm-- + pplleettee when the compspec was defined, and the compspec generates no + matches, bbaasshh attempts its default completions. If the compspec and, if attempted, the default bbaasshh completions generate no matches, and the - --oo ddeeffaauulltt option was supplied to ccoommpplleettee when the compspec was de- + --oo ddeeffaauulltt option was supplied to ccoommpplleettee when the compspec was de- fined, programmable completion performs rreeaaddlliinnee's default completion. - The options supplied to ccoommpplleettee and ccoommppoopptt can control how rreeaaddlliinnee - treats the completions. For instance, the _-_o _f_u_l_l_q_u_o_t_e option tells - rreeaaddlliinnee to quote the matches as if they were filenames. See the de- + The options supplied to ccoommpplleettee and ccoommppoopptt can control how rreeaaddlliinnee + treats the completions. For instance, the _-_o _f_u_l_l_q_u_o_t_e option tells + rreeaaddlliinnee to quote the matches as if they were filenames. See the de- scription of ccoommpplleettee below for details. - When a compspec indicates that it wants directory name completion, the - programmable completion functions force rreeaaddlliinnee to append a slash to + When a compspec indicates that it wants directory name completion, the + programmable completion functions force rreeaaddlliinnee to append a slash to completed names which are symbolic links to directories, subject to the value of the mmaarrkk--ddiirreeccttoorriieess rreeaaddlliinnee variable, regardless of the set- ting of the mmaarrkk--ssyymmlliinnkkeedd--ddiirreeccttoorriieess rreeaaddlliinnee variable. - There is some support for dynamically modifying completions. This is - most useful when used in combination with a default completion speci- - fied with ccoommpplleettee --DD. It's possible for shell functions executed as - completion functions to indicate that completion should be retried by - returning an exit status of 124. If a shell function returns 124, and + There is some support for dynamically modifying completions. This is + most useful when used in combination with a default completion speci- + fied with ccoommpplleettee --DD. It's possible for shell functions executed as + completion functions 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 + 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 can be used to - build a set of completions dynamically as completion is attempted, + attempt to find a new compspec for that command. This can be used to + build a set of completions dynamically as completion is attempted, rather than loading them all at once. - For instance, assuming that there is a library of compspecs, each kept - in a file corresponding to the name of the command, the following de- + For instance, assuming that there is a library of compspecs, each kept + in a file corresponding to the name of the command, the following de- fault completion function would load completions dynamically: _completion_loader() { @@ -4832,162 +4855,162 @@ RREEAADDLLIINNEE -o bashdefault -o default HHIISSTTOORRYY - When the --oo hhiissttoorryy option to the sseett builtin is enabled, the shell + When the --oo hhiissttoorryy option to the sseett builtin is enabled, the shell provides access to the _c_o_m_m_a_n_d _h_i_s_t_o_r_y, the list of commands previously - typed. The value of the HHIISSTTSSIIZZEE variable is used as the number of - commands to save in a history list: the shell saves the text of the + typed. The value of the HHIISSTTSSIIZZEE variable is used as the number of + commands to save in a history list: the shell saves the text of the last HHIISSTTSSIIZZEE commands (default 500). The shell stores each command in - the history list prior to parameter and variable expansion (see EEXXPPAANN-- - SSIIOONN above) but after history expansion is performed, subject to the + the history list prior to parameter and variable expansion (see EEXXPPAANN-- + SSIIOONN above) but after history expansion is performed, subject to the values of the shell variables HHIISSTTIIGGNNOORREE and HHIISSTTCCOONNTTRROOLL. - On startup, bbaasshh initializes the history list by reading history en- - tries from the file named by the HHIISSTTFFIILLEE variable (default - _~_/_._b_a_s_h___h_i_s_t_o_r_y). That file is referred to as the _h_i_s_t_o_r_y _f_i_l_e. The - history file is truncated, if necessary, to contain no more than the - number of history entries specified by the value of the HHIISSTTFFIILLEESSIIZZEE - variable. If HHIISSTTFFIILLEESSIIZZEE is unset, or set to null, a non-numeric + On startup, bbaasshh initializes the history list by reading history en- + tries from the file named by the HHIISSTTFFIILLEE variable (default + _~_/_._b_a_s_h___h_i_s_t_o_r_y). That file is referred to as the _h_i_s_t_o_r_y _f_i_l_e. The + history file is truncated, if necessary, to contain no more than the + number of history entries specified by the value of the HHIISSTTFFIILLEESSIIZZEE + variable. If HHIISSTTFFIILLEESSIIZZEE is unset, or set to null, a non-numeric value, or a numeric value less than zero, the history file is not trun- cated. When the history file is read, lines beginning with the history comment character followed immediately by a digit are interpreted as timestamps - for the following history line. These timestamps are optionally dis- - played depending on the value of the HHIISSTTTTIIMMEEFFOORRMMAATT variable. When - present, history timestamps delimit history entries, making multi-line + for the following history line. These timestamps are optionally dis- + played depending on the value of the HHIISSTTTTIIMMEEFFOORRMMAATT variable. When + present, history timestamps delimit history entries, making multi-line entries possible. When a shell with history enabled exits, bbaasshh copies the last $$HHIISSTTSSIIZZEE - entries from the history list to $$HHIISSTTFFIILLEE. If the hhiissttaappppeenndd shell - option is enabled (see the description of sshhoopptt under SSHHEELLLL BBUUIILLTTIINN - CCOOMMMMAANNDDSS below), bbaasshh appends the entries to the history file, other- - wise it overwrites the history file. If HHIISSTTFFIILLEE is unset or null, or - if the history file is unwritable, the history is not saved. After - saving the history, bbaasshh truncates the history file to contain no more + entries from the history list to $$HHIISSTTFFIILLEE. If the hhiissttaappppeenndd shell + option is enabled (see the description of sshhoopptt under SSHHEELLLL BBUUIILLTTIINN + CCOOMMMMAANNDDSS below), bbaasshh appends the entries to the history file, other- + wise it overwrites the history file. If HHIISSTTFFIILLEE is unset or null, or + if the history file is unwritable, the history is not saved. After + saving the history, bbaasshh truncates the history file to contain no more than HHIISSTTFFIILLEESSIIZZEE lines as described above. - If the HHIISSTTTTIIMMEEFFOORRMMAATT variable is set, the shell writes the timestamp - information associated with each history entry to the history file, - marked with the history comment character, so timestamps are preserved + If the HHIISSTTTTIIMMEEFFOORRMMAATT variable is set, the shell writes the timestamp + information associated with each history entry to the history file, + marked with the history comment character, so timestamps are preserved across shell sessions. This uses the history comment character to dis- - tinguish timestamps from other history lines. As above, when using + tinguish timestamps from other history lines. As above, when using HHIISSTTTTIIMMEEFFOORRMMAATT, the timestamps delimit multi-line history entries. - The ffcc builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below) will list or + The ffcc builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below) will list or edit and re-execute a portion of the history list. The hhiissttoorryy builtin can display or modify the history list and manipulate the history file. - When using command-line editing, search commands are available in each + When using command-line editing, search commands are available in each editing mode that provide access to the history list. - The shell allows control over which commands are saved on the history + The shell allows control over which commands are saved on the history list. The HHIISSTTCCOONNTTRROOLL and HHIISSTTIIGGNNOORREE variables are used to save only a - subset of the commands entered. If the ccmmddhhiisstt shell option is en- - abled, the shell attempts to save each line of a multi-line command in - the same history entry, adding semicolons where necessary to preserve - syntactic correctness. The lliitthhiisstt shell option modifies ccmmddhhiisstt by - saving the command with embedded newlines instead of semicolons. See + subset of the commands entered. If the ccmmddhhiisstt shell option is en- + abled, the shell attempts to save each line of a multi-line command in + the same history entry, adding semicolons where necessary to preserve + syntactic correctness. The lliitthhiisstt shell option modifies ccmmddhhiisstt by + saving the command with embedded newlines instead of semicolons. See the description of the sshhoopptt builtin below under SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS for information on setting and unsetting shell options. HHIISSTTOORRYY EEXXPPAANNSSIIOONN - The shell supports a history expansion feature that is similar to the - history expansion in ccsshh. This section describes what syntax features + The shell supports a history expansion feature that is similar to the + history expansion in ccsshh. This section describes what syntax features are available. History expansion is enabled by default for interactive shells, and can - be disabled using the ++HH option to the sseett builtin command (see SSHHEELLLL + be disabled using the ++HH option to the sseett builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). Non-interactive shells do not perform history expansion by default, but it can be enabled with "set -H". History expansions introduce words from the history list into the input - stream, making it easy to repeat commands, insert the arguments to a + stream, making it easy to repeat commands, insert the arguments to a previous command into the current input line, or fix errors in previous commands quickly. - History expansion is performed immediately after a complete line is - read, before the shell breaks it into words, and is performed on each - line individually. The shell attempts to inform the history expansion + History expansion is performed immediately after a complete line is + read, before the shell breaks it into words, and is performed on each + line individually. The shell attempts to inform the history expansion functions about quoting still in effect from previous lines. - It takes place in two parts. The first is to determine which history - list entry to use during substitution. The second is to select por- + It takes place in two parts. The first is to determine which history + list entry to use during substitution. The second is to select por- tions of that entry to include into the current one. - The entry selected from the history is the _e_v_e_n_t, and the portions of + The entry selected from the history is the _e_v_e_n_t, and the portions of that entry that are acted upon are _w_o_r_d_s. Various _m_o_d_i_f_i_e_r_s are avail- - able to manipulate the selected words. The entry is split into words - in the same fashion as when reading input, so that several _m_e_t_a_c_h_a_r_a_c_- - _t_e_r-separated words surrounded by quotes are considered one word. The - _e_v_e_n_t _d_e_s_i_g_n_a_t_o_r selects the event, the optional _w_o_r_d _d_e_s_i_g_n_a_t_o_r se- - lects words from the event, and various optional _m_o_d_i_f_i_e_r_s are avail- + able to manipulate the selected words. The entry is split into words + in the same fashion as when reading input, so that several _m_e_t_a_c_h_a_r_a_c_- + _t_e_r-separated words surrounded by quotes are considered one word. The + _e_v_e_n_t _d_e_s_i_g_n_a_t_o_r selects the event, the optional _w_o_r_d _d_e_s_i_g_n_a_t_o_r se- + lects words from the event, and various optional _m_o_d_i_f_i_e_r_s are avail- able to manipulate the selected words. - History expansions are introduced by the appearance of the history ex- - pansion character, which is !! by default. History expansions may ap- + History expansions are introduced by the appearance of the history ex- + pansion character, which is !! by default. History expansions may ap- pear anywhere in the input, but do not nest. - Only backslash (\\) and single quotes can quote the history expansion - character, but the history expansion character is also treated as + Only backslash (\\) and single quotes can quote the history expansion + character, but the history expansion character is also treated as quoted if it immediately precedes the closing double quote in a double- quoted string. - Several characters inhibit history expansion if found immediately fol- - lowing the history expansion character, even if it is unquoted: space, - tab, newline, carriage return, ==, and the other shell metacharacters + Several characters inhibit history expansion if found immediately fol- + lowing the history expansion character, even if it is unquoted: space, + tab, newline, carriage return, ==, and the other shell metacharacters defined above. There is a special abbreviation for substitution, active when the _q_u_i_c_k - _s_u_b_s_t_i_t_u_t_i_o_n character (described above under hhiissttcchhaarrss) is the first + _s_u_b_s_t_i_t_u_t_i_o_n character (described above under hhiissttcchhaarrss) is the first character on the line. It selects the previous history list entry, us- - ing an event designator equivalent to !!!!, and substitutes one string - for another in that entry. It is described below under EEvveenntt DDeessiiggnnaa-- - ttoorrss. This is the only history expansion that does not begin with the + ing an event designator equivalent to !!!!, and substitutes one string + for another in that entry. It is described below under EEvveenntt DDeessiiggnnaa-- + ttoorrss. This is the only history expansion that does not begin with the history expansion character. - Several shell options settable with the sshhoopptt builtin will modify his- - tory expansion behavior (see the description of the sshhoopptt builtin be- + Several shell options settable with the sshhoopptt builtin will modify his- + tory expansion behavior (see the description of the sshhoopptt builtin be- low).and If the hhiissttvveerriiffyy shell option is enabled, and rreeaaddlliinnee is be- ing used, history substitutions are not immediately passed to the shell parser. Instead, the expanded line is reloaded into the rreeaaddlliinnee edit- - ing buffer for further modification. If rreeaaddlliinnee is being used, and - the hhiissttrreeeeddiitt shell option is enabled, a failed history substitution + ing buffer for further modification. If rreeaaddlliinnee is being used, and + the hhiissttrreeeeddiitt shell option is enabled, a failed history substitution is reloaded into the rreeaaddlliinnee editing buffer for correction. - The --pp option to the hhiissttoorryy builtin command shows what a history ex- - pansion will do before using it. The --ss option to the hhiissttoorryy builtin - will add commands to the end of the history list without actually exe- + The --pp option to the hhiissttoorryy builtin command shows what a history ex- + pansion will do before using it. The --ss option to the hhiissttoorryy builtin + will add commands to the end of the history list without actually exe- cuting them, so that they are available for subsequent recall. - The shell allows control of the various characters used by the history + The shell allows control of the various characters used by the history expansion mechanism (see the description of hhiissttcchhaarrss above under SShheellll - VVaarriiaabblleess). The shell uses the history comment character to mark his- + VVaarriiaabblleess). The shell uses the history comment character to mark his- tory timestamps when writing the history file. EEvveenntt DDeessiiggnnaattoorrss - An event designator is a reference to an entry in the history list. + An event designator is a reference to an entry in the history list. The event designator consists of the portion of the word beginning with - the history expansion character and ending with the word designator if - present, or the end of the word. Unless the reference is absolute, + the history expansion character and ending with the word designator if + present, or the end of the word. Unless the reference is absolute, events are relative to the current position in the history list. - !! Start a history substitution, except when followed by a bbllaannkk, - newline, carriage return, =, or, when the eexxttgglloobb shell option + !! Start a history substitution, except when followed by a bbllaannkk, + newline, carriage return, =, or, when the eexxttgglloobb shell option is enabled using the sshhoopptt builtin, (. !!_n Refer to history list entry _n. !!--_n Refer to the current entry minus _n. !!!! Refer to the previous entry. This is a synonym for "!-1". !!_s_t_r_i_n_g - Refer to the most recent command preceding the current position + Refer to the most recent command preceding the current position in the history list starting with _s_t_r_i_n_g. !!??_s_t_r_i_n_g[[??]] - Refer to the most recent command preceding the current position - in the history list containing _s_t_r_i_n_g. The trailing ?? may be - omitted if _s_t_r_i_n_g is followed immediately by a newline. If - _s_t_r_i_n_g is missing, this uses the string from the most recent + Refer to the most recent command preceding the current position + in the history list containing _s_t_r_i_n_g. The trailing ?? may be + omitted if _s_t_r_i_n_g is followed immediately by a newline. If + _s_t_r_i_n_g is missing, this uses the string from the most recent search; it is an error if there is no previous search string. ^^_s_t_r_i_n_g_1^^_s_t_r_i_n_g_2^^ - Quick substitution. Repeat the previous command, replacing - _s_t_r_i_n_g_1 with _s_t_r_i_n_g_2. Equivalent to "!!:s^_s_t_r_i_n_g_1^_s_t_r_i_n_g_2^" + Quick substitution. Repeat the previous command, replacing + _s_t_r_i_n_g_1 with _s_t_r_i_n_g_2. Equivalent to "!!:s^_s_t_r_i_n_g_1^_s_t_r_i_n_g_2^" (see MMooddiiffiieerrss below). !!## The entire command line typed so far. @@ -4995,37 +5018,37 @@ HHIISSTTOORRYY EEXXPPAANNSSIIOONN Word designators are used to select desired words from the event. They are optional; if the word designator isn't supplied, the history expan- sion uses the entire event. A :: separates the event specification from - the word designator. It may be omitted if the word designator begins - with a ^^, $$, **, --, or %%. Words are numbered from the beginning of the - line, with the first word being denoted by 0 (zero). Words are in- + the word designator. It may be omitted if the word designator begins + with a ^^, $$, **, --, or %%. Words are numbered from the beginning of the + line, with the first word being denoted by 0 (zero). Words are in- serted into the current line separated by single spaces. 00 ((zzeerroo)) The zeroth word. For the shell, this is the command word. _n The _nth word. ^^ The first argument: word 1. - $$ The last word. This is usually the last argument, but will ex- + $$ The last word. This is usually the last argument, but will ex- pand to the zeroth word if there is only one word in the line. %% The first word matched by the most recent "?_s_t_r_i_n_g?" search, if - the search string begins with a character that is part of a - word. By default, searches begin at the end of each line and - proceed to the beginning, so the first word matched is the one + the search string begins with a character that is part of a + word. By default, searches begin at the end of each line and + proceed to the beginning, so the first word matched is the one closest to the end of the line. _x--_y A range of words; "-_y" abbreviates "0-_y". - ** All of the words but the zeroth. This is a synonym for "_1_-_$". - It is not an error to use ** if there is just one word in the + ** All of the words but the zeroth. This is a synonym for "_1_-_$". + It is not an error to use ** if there is just one word in the event; it expands to the empty string in that case. xx** Abbreviates _x_-_$. xx-- Abbreviates _x_-_$ like xx**, but omits the last word. If xx is miss- ing, it defaults to 0. - If a word designator is supplied without an event specification, the + If a word designator is supplied without an event specification, the previous command is used as the event, equivalent to !!!!. MMooddiiffiieerrss - After the optional word designator, the expansion may include a se- - quence of one or more of the following modifiers, each preceded by a - ":". These modify, or edit, the word or words selected from the his- + After the optional word designator, the expansion may include a se- + quence of one or more of the following modifiers, each preceded by a + ":". These modify, or edit, the word or words selected from the his- tory event. hh Remove a trailing pathname component, leaving only the head. @@ -5034,24 +5057,24 @@ HHIISSTTOORRYY EEXXPPAANNSSIIOONN ee Remove all but the trailing suffix. pp Print the new command but do not execute it. qq Quote the substituted words, escaping further substitutions. - xx Quote the substituted words as with qq, but break into words at - bbllaannkkss and newlines. The qq and xx modifiers are mutually exclu- + xx Quote the substituted words as with qq, but break into words at + bbllaannkkss and newlines. The qq and xx modifiers are mutually exclu- sive; expansion uses the last one supplied. ss//_o_l_d//_n_e_w// - Substitute _n_e_w for the first occurrence of _o_l_d in the event + Substitute _n_e_w for the first occurrence of _o_l_d in the event line. Any character may be used as the delimiter in place of /. - The final delimiter is optional if it is the last character of - the event line. A single backslash quotes the delimiter in _o_l_d - and _n_e_w. If & appears in _n_e_w, it is replaced with _o_l_d. A sin- - gle backslash quotes the &. If _o_l_d is null, it is set to the - last _o_l_d substituted, or, if no previous history substitutions + The final delimiter is optional if it is the last character of + the event line. A single backslash quotes the delimiter in _o_l_d + and _n_e_w. If & appears in _n_e_w, it is replaced with _o_l_d. A sin- + gle backslash quotes the &. If _o_l_d is null, it is set to the + last _o_l_d substituted, or, if no previous history substitutions took place, the last _s_t_r_i_n_g in a !!??_s_t_r_i_n_g[[??]] search. If _n_e_w is null, each matching _o_l_d is deleted. && Repeat the previous substitution. gg Cause changes to be applied over the entire event line. This is - used in conjunction with "::ss" (e.g., "::ggss//_o_l_d//_n_e_w//") or "::&&". - If used with "::ss", any delimiter can be used in place of /, and - the final delimiter is optional if it is the last character of + used in conjunction with "::ss" (e.g., "::ggss//_o_l_d//_n_e_w//") or "::&&". + If used with "::ss", 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 aa may be used as a synonym for gg. GG Apply the following "ss" or "&&" modifier once to each word in the event line. @@ -5060,64 +5083,64 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS Unless otherwise noted, each builtin command documented in this section as accepting options preceded by -- accepts ---- to signify the end of the options. The ::, ttrruuee, ffaallssee, and tteesstt/[[ builtins do not accept options - and do not treat ---- specially. The eexxiitt, llooggoouutt, rreettuurrnn, bbrreeaakk, ccoonn-- - ttiinnuuee, lleett, and sshhiifftt builtins accept and process arguments beginning - with -- without requiring ----. Other builtins that accept arguments but - are not specified as accepting options interpret arguments beginning - with -- as invalid options and require ---- to prevent this interpreta- + and do not treat ---- specially. The eexxiitt, llooggoouutt, rreettuurrnn, bbrreeaakk, ccoonn-- + ttiinnuuee, lleett, and sshhiifftt builtins accept and process arguments beginning + with -- without requiring ----. Other builtins that accept arguments but + are not specified as accepting options interpret arguments beginning + with -- as invalid options and require ---- to prevent this interpreta- tion. :: [_a_r_g_u_m_e_n_t_s] - No effect; the command does nothing beyond expanding _a_r_g_u_m_e_n_t_s + No effect; the command does nothing beyond expanding _a_r_g_u_m_e_n_t_s and performing any specified redirections. The return status is zero. .. [--pp _p_a_t_h] _f_i_l_e_n_a_m_e [_a_r_g_u_m_e_n_t_s] ssoouurrccee [--pp _p_a_t_h] _f_i_l_e_n_a_m_e [_a_r_g_u_m_e_n_t_s] - The .. command (ssoouurrccee) reads and execute commands from _f_i_l_e_n_a_m_e - in the current shell environment and returns the exit status of + The .. command (ssoouurrccee) reads and execute commands from _f_i_l_e_n_a_m_e + in the current shell environment and returns the exit status of the last command executed from _f_i_l_e_n_a_m_e. If _f_i_l_e_n_a_m_e does not contain a slash, .. searches for it. If the - --pp option is supplied, .. treats _p_a_t_h as a colon-separated list - of directories in which to find _f_i_l_e_n_a_m_e; otherwise, .. uses the - entries in PPAATTHH to find the directory containing _f_i_l_e_n_a_m_e. - _f_i_l_e_n_a_m_e does not need to be executable. When bbaasshh is not in + --pp option is supplied, .. treats _p_a_t_h as a colon-separated list + of directories in which to find _f_i_l_e_n_a_m_e; otherwise, .. uses the + entries in PPAATTHH to find the directory containing _f_i_l_e_n_a_m_e. + _f_i_l_e_n_a_m_e does not need to be executable. When bbaasshh is not in posix mode, it searches the current directory if _f_i_l_e_n_a_m_e is not - found in PPAATTHH, but does not search the current directory if --pp + found in PPAATTHH, but does not search the current directory if --pp is supplied. If the ssoouurrcceeppaatthh option to the sshhoopptt builtin com- mand is turned off, .. does not search PPAATTHH. - If any _a_r_g_u_m_e_n_t_s are supplied, they become the positional para- - meters when _f_i_l_e_n_a_m_e is executed. Otherwise the positional pa- + If any _a_r_g_u_m_e_n_t_s are supplied, they become the positional para- + meters when _f_i_l_e_n_a_m_e is executed. Otherwise the positional pa- rameters are unchanged. If the --TT option is enabled, .. inherits any trap on DDEEBBUUGG; if it - is not, any DDEEBBUUGG trap string is saved and restored around the + is not, any DDEEBBUUGG trap string is saved and restored around the call to .., and .. unsets the DDEEBBUUGG trap while it executes. If --TT is not set, and the sourced file changes the DDEEBBUUGG trap, the new value persists after .. completes. The return status is the sta- tus of the last command executed from _f_i_l_e_n_a_m_e (0 if no commands - are executed), and non-zero if _f_i_l_e_n_a_m_e is not found or cannot + are executed), and non-zero if _f_i_l_e_n_a_m_e is not found or cannot be read. aalliiaass [--pp] [_n_a_m_e[=_v_a_l_u_e] ...] - With no arguments or with the --pp option, aalliiaass prints the list - of aliases in the form aalliiaass _n_a_m_e=_v_a_l_u_e on standard output. + With no arguments or with the --pp option, aalliiaass prints the list + of aliases in the form aalliiaass _n_a_m_e=_v_a_l_u_e on standard output. When arguments are supplied, define an alias for each _n_a_m_e whose - _v_a_l_u_e is given. A trailing space in _v_a_l_u_e causes the next word - to be checked for alias substitution when the alias is expanded - during command parsing. For each _n_a_m_e in the argument list for - which no _v_a_l_u_e is supplied, print the name and value of the - alias _n_a_m_e. aalliiaass returns true unless a _n_a_m_e is given (without + _v_a_l_u_e is given. A trailing space in _v_a_l_u_e causes the next word + to be checked for alias substitution when the alias is expanded + during command parsing. For each _n_a_m_e in the argument list for + which no _v_a_l_u_e is supplied, print the name and value of the + alias _n_a_m_e. aalliiaass returns true unless a _n_a_m_e is given (without a corresponding =_v_a_l_u_e) for which no alias has been defined. bbgg [_j_o_b_s_p_e_c ...] - Resume each suspended job _j_o_b_s_p_e_c in the background, as if it - had been started with &&. If _j_o_b_s_p_e_c is not present, the shell + Resume each suspended job _j_o_b_s_p_e_c in the background, as if it + had been started with &&. If _j_o_b_s_p_e_c is not present, the shell uses its notion of the _c_u_r_r_e_n_t _j_o_b. bbgg _j_o_b_s_p_e_c returns 0 unless - run when job control is disabled or, when run with job control - enabled, any specified _j_o_b_s_p_e_c was not found or was started + run when job control is disabled or, when run with job control + enabled, any specified _j_o_b_s_p_e_c was not found or was started without job control. bbiinndd [--mm _k_e_y_m_a_p] [--llssvvSSVVXX] @@ -5128,192 +5151,192 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS bbiinndd [--mm _k_e_y_m_a_p] --pp|--PP [_r_e_a_d_l_i_n_e_-_c_o_m_m_a_n_d] bbiinndd [--mm _k_e_y_m_a_p] _k_e_y_s_e_q:_r_e_a_d_l_i_n_e_-_c_o_m_m_a_n_d bbiinndd _r_e_a_d_l_i_n_e_-_c_o_m_m_a_n_d_-_l_i_n_e - Display current rreeaaddlliinnee key and function bindings, bind a key - sequence to a rreeaaddlliinnee function or macro or to a shell command, - or set a rreeaaddlliinnee variable. Each non-option argument is a key - binding or command as it would appear in a rreeaaddlliinnee initializa- - tion file such as _._i_n_p_u_t_r_c, but each binding or command must be - passed as a separate argument; e.g., '"\C-x\C-r": - re-read-init-file'. In the following descriptions, output - available to be re-read is formatted as commands that would ap- + Display current rreeaaddlliinnee key and function bindings, bind a key + sequence to a rreeaaddlliinnee function or macro or to a shell command, + or set a rreeaaddlliinnee variable. Each non-option argument is a key + binding or command as it would appear in a rreeaaddlliinnee initializa- + tion file such as _._i_n_p_u_t_r_c, but each binding or command must be + passed as a separate argument; e.g., '"\C-x\C-r": + re-read-init-file'. In the following descriptions, output + available to be re-read is formatted as commands that would ap- pear in a rreeaaddlliinnee initialization file or that would be supplied - as individual arguments to a bbiinndd command. Options, if sup- + as individual arguments to a bbiinndd command. Options, if sup- plied, have the following meanings: --mm _k_e_y_m_a_p Use _k_e_y_m_a_p as the keymap to be affected by the subsequent bindings. Acceptable _k_e_y_m_a_p names are _e_m_a_c_s_, _e_m_a_c_s_-_s_t_a_n_- - _d_a_r_d_, _e_m_a_c_s_-_m_e_t_a_, _e_m_a_c_s_-_c_t_l_x_, _v_i_, _v_i_-_m_o_v_e_, _v_i_-_c_o_m_m_a_n_d, - and _v_i_-_i_n_s_e_r_t. _v_i is equivalent to _v_i_-_c_o_m_m_a_n_d (_v_i_-_m_o_v_e - is also a synonym); _e_m_a_c_s is equivalent to _e_m_a_c_s_-_s_t_a_n_- + _d_a_r_d_, _e_m_a_c_s_-_m_e_t_a_, _e_m_a_c_s_-_c_t_l_x_, _v_i_, _v_i_-_m_o_v_e_, _v_i_-_c_o_m_m_a_n_d, + and _v_i_-_i_n_s_e_r_t. _v_i is equivalent to _v_i_-_c_o_m_m_a_n_d (_v_i_-_m_o_v_e + is also a synonym); _e_m_a_c_s is equivalent to _e_m_a_c_s_-_s_t_a_n_- _d_a_r_d. --ll List the names of all rreeaaddlliinnee functions. - --pp Display rreeaaddlliinnee function names and bindings in such a - way that they can be used as an argument to a subsequent - bbiinndd command or in a rreeaaddlliinnee initialization file. If - arguments remain after option processing, bbiinndd treats - them as rreeaaddlliinnee command names and restricts output to - those names. - --PP List current rreeaaddlliinnee function names and bindings. If + --pp Display rreeaaddlliinnee function names and bindings in such a + way that they can be used as an argument to a subsequent + bbiinndd command or in a rreeaaddlliinnee initialization file. If arguments remain after option processing, bbiinndd treats them as rreeaaddlliinnee command names and restricts output to those names. - --ss Display rreeaaddlliinnee key sequences bound to macros and the - strings they output in such a way that they can be used + --PP List current rreeaaddlliinnee function names and bindings. If + arguments remain after option processing, bbiinndd treats + them as rreeaaddlliinnee command names and restricts output to + those names. + --ss Display rreeaaddlliinnee key sequences bound to macros and the + strings they output in such a way that they can be used as an argument to a subsequent bbiinndd command or in a rreeaadd-- lliinnee initialization file. - --SS Display rreeaaddlliinnee key sequences bound to macros and the + --SS Display rreeaaddlliinnee key sequences bound to macros and the strings they output. - --vv Display rreeaaddlliinnee variable names and values in such a way + --vv Display rreeaaddlliinnee variable names and values in such a way that they can be used as an argument to a subsequent bbiinndd command or in a rreeaaddlliinnee initialization file. --VV List current rreeaaddlliinnee variable names and values. --ff _f_i_l_e_n_a_m_e Read key bindings from _f_i_l_e_n_a_m_e. --qq _f_u_n_c_t_i_o_n - Display key sequences that invoke the named rreeaaddlliinnee + Display key sequences that invoke the named rreeaaddlliinnee _f_u_n_c_t_i_o_n. --uu _f_u_n_c_t_i_o_n - Unbind all key sequences bound to the named rreeaaddlliinnee + Unbind all key sequences bound to the named rreeaaddlliinnee _f_u_n_c_t_i_o_n. --rr _k_e_y_s_e_q Remove any current binding for _k_e_y_s_e_q. --xx _k_e_y_s_e_q[[:: ]]_s_h_e_l_l_-_c_o_m_m_a_n_d Cause _s_h_e_l_l_-_c_o_m_m_a_n_d to be executed whenever _k_e_y_s_e_q is en- tered. The separator between _k_e_y_s_e_q and _s_h_e_l_l_-_c_o_m_m_a_n_d is - either whitespace or a colon optionally followed by - whitespace. If the separator is whitespace, _s_h_e_l_l_-_c_o_m_- - _m_a_n_d must be enclosed in double quotes and rreeaaddlliinnee ex- - pands any of its special backslash-escapes in _s_h_e_l_l_-_c_o_m_- - _m_a_n_d before saving it. If the separator is a colon, any - enclosing double quotes are optional, and rreeaaddlliinnee does - not expand the command string before saving it. Since - the entire key binding expression must be a single argu- - ment, it should be enclosed in single quotes. When - _s_h_e_l_l_-_c_o_m_m_a_n_d is executed, the shell sets the RREEAADD-- - LLIINNEE__LLIINNEE variable to the contents of the rreeaaddlliinnee line + either whitespace or a colon optionally followed by + whitespace. If the separator is whitespace, _s_h_e_l_l_-_c_o_m_- + _m_a_n_d must be enclosed in double quotes and rreeaaddlliinnee ex- + pands any of its special backslash-escapes in _s_h_e_l_l_-_c_o_m_- + _m_a_n_d before saving it. If the separator is a colon, any + enclosing double quotes are optional, and rreeaaddlliinnee does + not expand the command string before saving it. Since + the entire key binding expression must be a single argu- + ment, it should be enclosed in single quotes. When + _s_h_e_l_l_-_c_o_m_m_a_n_d is executed, the shell sets the RREEAADD-- + LLIINNEE__LLIINNEE variable to the contents of the rreeaaddlliinnee line buffer and the RREEAADDLLIINNEE__PPOOIINNTT and RREEAADDLLIINNEE__MMAARRKK variables - to the current location of the insertion point and the - saved insertion point (the mark), respectively. The - shell assigns any numeric argument the user supplied to - the RREEAADDLLIINNEE__AARRGGUUMMEENNTT variable. If there was no argu- - ment, that variable is not set. If the executed command - changes the value of any of RREEAADDLLIINNEE__LLIINNEE, RREEAADD-- - LLIINNEE__PPOOIINNTT, or RREEAADDLLIINNEE__MMAARRKK, those new values will be + to the current location of the insertion point and the + saved insertion point (the mark), respectively. The + shell assigns any numeric argument the user supplied to + the RREEAADDLLIINNEE__AARRGGUUMMEENNTT variable. If there was no argu- + ment, that variable is not set. If the executed command + changes the value of any of RREEAADDLLIINNEE__LLIINNEE, RREEAADD-- + LLIINNEE__PPOOIINNTT, or RREEAADDLLIINNEE__MMAARRKK, those new values will be reflected in the editing state. - --XX List all key sequences bound to shell commands and the - associated commands in a format that can be reused as an + --XX List all key sequences bound to shell commands and the + associated commands in a format that can be reused as an argument to a subsequent bbiinndd command. - The return value is 0 unless an unrecognized option is supplied + The return value is 0 unless an unrecognized option is supplied or an error occurred. bbrreeaakk [_n] - Exit from within a ffoorr, wwhhiillee, uunnttiill, or sseelleecctt loop. If _n is + Exit from within a ffoorr, wwhhiillee, uunnttiill, or sseelleecctt loop. If _n is specified, bbrreeaakk exits _n enclosing loops. _n must be >= 1. If _n - is greater than the number of enclosing loops, all enclosing + is greater than the number of enclosing loops, all enclosing loops are exited. The return value is 0 unless _n is not greater than or equal to 1. bbuuiillttiinn _s_h_e_l_l_-_b_u_i_l_t_i_n [_a_r_g_u_m_e_n_t_s] - Execute the specified shell builtin _s_h_e_l_l_-_b_u_i_l_t_i_n, passing it - _a_r_g_u_m_e_n_t_s, 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 ccdd builtin is commonly redefined this way. The return sta- + Execute the specified shell builtin _s_h_e_l_l_-_b_u_i_l_t_i_n, passing it + _a_r_g_u_m_e_n_t_s, 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 ccdd builtin is commonly redefined this way. The return sta- tus is false if _s_h_e_l_l_-_b_u_i_l_t_i_n is not a shell builtin command. ccaalllleerr [_e_x_p_r] Returns the context of any active subroutine call (a shell func- tion or a script executed with the .. or ssoouurrccee builtins). - Without _e_x_p_r, ccaalllleerr displays the line number and source file- - name of the current subroutine call. If a non-negative integer + Without _e_x_p_r, ccaalllleerr displays the line number and source file- + name of the current subroutine call. If a non-negative integer is supplied as _e_x_p_r, ccaalllleerr displays the line number, subroutine name, and source file corresponding to that position in the cur- - rent execution call stack. This extra information may be used, + rent 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 sub- - routine call or _e_x_p_r does not correspond to a valid position in + The return value is 0 unless the shell is not executing a sub- + routine call or _e_x_p_r does not correspond to a valid position in the call stack. ccdd [--LL] [--@@] [_d_i_r] ccdd --PP [--ee] [--@@] [_d_i_r] - Change the current directory to _d_i_r. if _d_i_r is not supplied, - the value of the HHOOMMEE shell variable is used as _d_i_r. If _d_i_r is + Change the current directory to _d_i_r. if _d_i_r is not supplied, + the value of the HHOOMMEE shell variable is used as _d_i_r. If _d_i_r is the empty string, ccdd treats it as an error. The variable CCDDPPAATTHH exists, and _d_i_r does not begin with a slash (/), ccdd uses it as a - search path: the shell searches each directory name in CCDDPPAATTHH + search path: the shell searches each directory name in CCDDPPAATTHH for _d_i_r. Alternative directory names in CCDDPPAATTHH are separated by a colon (:). A null directory name in CCDDPPAATTHH is the same as the current directory, i.e., ".". - The --PP option causes ccdd to use the physical directory structure + The --PP option causes ccdd to use the physical directory structure by resolving symbolic links while traversing _d_i_r and before pro- - cessing instances of _._. in _d_i_r (see also the --PP option to the + cessing instances of _._. in _d_i_r (see also the --PP option to the sseett builtin command). - The --LL option forces ccdd to follow symbolic links by resolving + The --LL option forces ccdd to follow symbolic links by resolving the link after processing instances of _._. in _d_i_r. If _._. appears - in _d_i_r, ccdd processes it by removing the immediately previous + in _d_i_r, ccdd processes it by removing the immediately previous pathname component from _d_i_r, back to a slash or the beginning of - _d_i_r, and verifying that the portion of _d_i_r it has processed to - that point is still a valid directory name after removing the + _d_i_r, and verifying that the portion of _d_i_r it has processed to + that point is still a valid directory name after removing the pathname component. If it is not a valid directory name, ccdd re- - turns a non-zero status. If neither --LL nor --PP is supplied, ccdd + turns a non-zero status. If neither --LL nor --PP is supplied, ccdd behaves as if --LL had been supplied. If the --ee option is supplied with --PP, and ccdd cannot successfully - determine the current working directory after a successful di- + determine the current working directory after a successful di- rectory change, it returns a non-zero status. - On systems that support it, the --@@ option presents the extended + On systems that support it, the --@@ option presents the extended attributes associated with a file as a directory. - An argument of -- is converted to $$OOLLDDPPWWDD before attempting the + An argument of -- is converted to $$OOLLDDPPWWDD before attempting the directory change. - If ccdd uses a non-empty directory name from CCDDPPAATTHH, or if -- is - the first argument, and the directory change is successful, ccdd + If ccdd uses a non-empty directory name from CCDDPPAATTHH, or if -- is + the first argument, and the directory change is successful, ccdd writes the absolute pathname of the new working directory to the standard output. - If the directory change is successful, ccdd sets the value of the + If the directory change is successful, ccdd sets the value of the PPWWDD environment variable to the new directory name, and sets the - OOLLDDPPWWDD environment variable to the value of the current working + OOLLDDPPWWDD environment variable to the value of the current working directory before the change. - The return value is true if the directory was successfully + The return value is true if the directory was successfully changed; false otherwise. ccoommmmaanndd [--ppVVvv] _c_o_m_m_a_n_d [_a_r_g ...] - The ccoommmmaanndd builtin runs _c_o_m_m_a_n_d with _a_r_g_s suppressing the nor- + The ccoommmmaanndd builtin runs _c_o_m_m_a_n_d with _a_r_g_s suppressing the nor- mal shell function lookup for _c_o_m_m_a_n_d. Only builtin commands or - commands found in the PPAATTHH named _c_o_m_m_a_n_d are executed. If the + commands found in the PPAATTHH named _c_o_m_m_a_n_d are executed. If the --pp option is supplied, the search for _c_o_m_m_a_n_d is performed using - a default value for PPAATTHH that is guaranteed to find all of the + a default value for PPAATTHH that is guaranteed to find all of the standard utilities. - If either the --VV or --vv option is supplied, ccoommmmaanndd prints a de- - scription of _c_o_m_m_a_n_d. The --vv option displays a single word in- - dicating the command or filename used to invoke _c_o_m_m_a_n_d; the --VV + If either the --VV or --vv option is supplied, ccoommmmaanndd prints a de- + scription of _c_o_m_m_a_n_d. The --vv option displays a single word in- + dicating the command or filename used to invoke _c_o_m_m_a_n_d; the --VV option produces a more verbose description. - If the --VV or --vv option is supplied, the exit status is zero if - _c_o_m_m_a_n_d was found, and non-zero if not. If neither option is - supplied and an error occurred or _c_o_m_m_a_n_d cannot be found, the - exit status is 127. Otherwise, the exit status of the ccoommmmaanndd + If the --VV or --vv option is supplied, the exit status is zero if + _c_o_m_m_a_n_d was found, and non-zero if not. If neither option is + supplied and an error occurred or _c_o_m_m_a_n_d cannot be found, the + exit status is 127. Otherwise, the exit status of the ccoommmmaanndd builtin is the exit status of _c_o_m_m_a_n_d. ccoommppggeenn [--VV _v_a_r_n_a_m_e] [_o_p_t_i_o_n] [_w_o_r_d] - Generate possible completion matches for _w_o_r_d according to the - _o_p_t_i_o_ns, which may be any option accepted by the ccoommpplleettee + Generate possible completion matches for _w_o_r_d according to the + _o_p_t_i_o_ns, which may be any option accepted by the ccoommpplleettee builtin with the exceptions of --pp, --rr, --DD, --EE, and --II, and write the matches to the standard output. - If the --VV option is supplied, ccoommppggeenn stores the generated com- - pletions into the indexed array variable _v_a_r_n_a_m_e instead of + If the --VV option is supplied, ccoommppggeenn stores the generated com- + pletions into the indexed array variable _v_a_r_n_a_m_e instead of writing them to the standard output. When using the --FF or --CC options, the various shell variables set @@ -5322,11 +5345,11 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS The matches will be generated in the same way as if the program- mable completion code had generated them directly from a comple- - tion specification with the same flags. If _w_o_r_d is specified, - only those completions matching _w_o_r_d will be displayed or + tion specification with the same flags. If _w_o_r_d is specified, + only those completions matching _w_o_r_d will be displayed or stored. - The return value is true unless an invalid option is supplied, + The return value is true unless an invalid option is supplied, or no matches were generated. ccoommpplleettee [--aabbccddeeffggjjkkssuuvv] [--oo _c_o_m_p_-_o_p_t_i_o_n] [--DDEEII] [--AA _a_c_t_i_o_n] @@ -5336,78 +5359,78 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS Specify how arguments to each _n_a_m_e should be completed. If the --pp option is supplied, or if no options or _n_a_m_es are sup- - plied, print existing completion specifications in a way that + plied, print existing completion specifications in a way that allows them to be reused as input. The --rr option removes a com- - pletion specification for each _n_a_m_e, or, if no _n_a_m_es are sup- + pletion specification for each _n_a_m_e, or, if no _n_a_m_es are sup- plied, all completion specifications. - The --DD option indicates that other supplied options and actions - should apply to the "default" command completion; that is, com- - pletion attempted on a command for which no completion has pre- - viously been defined. The --EE option indicates that other sup- - plied options and actions should apply to "empty" command com- - pletion; that is, completion attempted on a blank line. The --II - option indicates that other supplied options and actions should - apply to completion on the initial non-assignment word on the + The --DD option indicates that other supplied options and actions + should apply to the "default" command completion; that is, com- + pletion attempted on a command for which no completion has pre- + viously been defined. The --EE option indicates that other sup- + plied options and actions should apply to "empty" command com- + pletion; that is, completion attempted on a blank line. The --II + option indicates that other supplied options and actions should + apply to completion on the initial non-assignment word on the line, or after a command delimiter such as ;; or ||, which is usu- ally command name completion. If multiple options are supplied, the --DD option takes precedence over --EE, and both take precedence - over --II. If any of --DD, --EE, or --II are supplied, any other _n_a_m_e - arguments are ignored; these completions only apply to the case + over --II. If any of --DD, --EE, or --II are supplied, any other _n_a_m_e + arguments are ignored; these completions only apply to the case specified by the option. The process of applying these completion specifications when at- - tempting word completion is described above under PPrrooggrraammmmaabbllee + tempting word completion is described above under PPrrooggrraammmmaabbllee CCoommpplleettiioonn. - Other options, if specified, have the following meanings. The - arguments to the --GG, --WW, and --XX options (and, if necessary, the - --PP and --SS options) should be quoted to protect them from expan- + Other options, if specified, have the following meanings. The + arguments to the --GG, --WW, and --XX options (and, if necessary, the + --PP and --SS options) should be quoted to protect them from expan- sion before the ccoommpplleettee builtin is invoked. --oo _c_o_m_p_-_o_p_t_i_o_n - The _c_o_m_p_-_o_p_t_i_o_n controls several aspects of the comp- - spec's behavior beyond the simple generation of comple- + The _c_o_m_p_-_o_p_t_i_o_n controls several aspects of the comp- + spec's behavior beyond the simple generation of comple- tions. _c_o_m_p_-_o_p_t_i_o_n may be one of: bbaasshhddeeffaauulltt Perform the rest of the default bbaasshh completions if the compspec generates no matches. - ddeeffaauulltt Use rreeaaddlliinnee's default filename completion if + ddeeffaauulltt Use rreeaaddlliinnee's default filename completion if the compspec generates no matches. ddiirrnnaammeess - Perform directory name completion if the comp- + Perform directory name completion if the comp- spec generates no matches. ffiilleennaammeess - Tell rreeaaddlliinnee that the compspec generates file- - names, so it can perform any filename-specific - processing (such as adding a slash to directory - names, quoting special characters, or suppress- - ing trailing spaces). This is intended to be + Tell rreeaaddlliinnee that the compspec generates file- + names, so it can perform any filename-specific + processing (such as adding a slash to directory + names, quoting special characters, or suppress- + ing trailing spaces). This is intended to be used with shell functions. ffuullllqquuoottee - Tell rreeaaddlliinnee to quote all the completed words + Tell rreeaaddlliinnee to quote all the completed words even if they are not filenames. - nnooqquuoottee Tell rreeaaddlliinnee not to quote the completed words - if they are filenames (quoting filenames is the + nnooqquuoottee Tell rreeaaddlliinnee not to quote the completed words + if they are filenames (quoting filenames is the default). - nnoossoorrtt Tell rreeaaddlliinnee not to sort the list of possible + nnoossoorrtt Tell rreeaaddlliinnee not to sort the list of possible completions alphabetically. - nnoossppaaccee Tell rreeaaddlliinnee not to append a space (the de- - fault) to words completed at the end of the + nnoossppaaccee Tell rreeaaddlliinnee not to append a space (the de- + fault) to words completed at the end of the line. pplluussddiirrss - After generating any matches defined by the - compspec, attempt directory name completion and - add any matches to the results of the other ac- + After generating any matches defined by the + compspec, attempt directory name completion and + add any matches to the results of the other ac- tions. --AA _a_c_t_i_o_n - The _a_c_t_i_o_n may be one of the following to generate a + The _a_c_t_i_o_n may be one of the following to generate a list of possible completions: aalliiaass Alias names. May also be specified as --aa. aarrrraayyvvaarr Array variable names. bbiinnddiinngg RReeaaddlliinnee key binding names. - bbuuiillttiinn Names of shell builtin commands. May also be + bbuuiillttiinn Names of shell builtin commands. May also be specified as --bb. ccoommmmaanndd Command names. May also be specified as --cc. ddiirreeccttoorryy @@ -5415,10 +5438,10 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS ddiissaabblleedd Names of disabled shell builtins. eennaabblleedd Names of enabled shell builtins. - eexxppoorrtt Names of exported shell variables. May also be + eexxppoorrtt Names of exported shell variables. May also be specified as --ee. - ffiillee File and directory names, similar to rreeaaddlliinnee's - filename completion. May also be specified as + ffiillee File and directory names, similar to rreeaaddlliinnee's + filename completion. May also be specified as --ff. ffuunnccttiioonn Names of shell functions. @@ -5426,17 +5449,17 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS hheellppttooppiicc Help topics as accepted by the hheellpp builtin. hhoossttnnaammee - Hostnames, as taken from the file specified by + Hostnames, as taken from the file specified by the HHOOSSTTFFIILLEE shell variable. - jjoobb Job names, if job control is active. May also + jjoobb Job names, if job control is active. May also be specified as --jj. - kkeeyywwoorrdd Shell reserved words. May also be specified as + kkeeyywwoorrdd Shell reserved words. May also be specified as --kk. rruunnnniinngg Names of running jobs, if job control is active. sseerrvviiccee Service names. May also be specified as --ss. - sseettoopptt Valid arguments for the --oo option to the sseett + sseettoopptt Valid arguments for the --oo option to the sseett builtin. - sshhoopptt Shell option names as accepted by the sshhoopptt + sshhoopptt Shell option names as accepted by the sshhoopptt builtin. ssiiggnnaall Signal names. ssttooppppeedd Names of stopped jobs, if job control is active. @@ -5445,219 +5468,219 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS Names of all shell variables. May also be spec- ified as --vv. --CC _c_o_m_m_a_n_d - _c_o_m_m_a_n_d is executed in a subshell environment, and its - output is used as the possible completions. Arguments + _c_o_m_m_a_n_d is executed in a subshell environment, and its + output is used as the possible completions. Arguments are passed as with the --FF option. --FF _f_u_n_c_t_i_o_n - The shell function _f_u_n_c_t_i_o_n is executed in the current - shell environment. When the function is executed, the + The shell function _f_u_n_c_t_i_o_n is executed in the current + shell environment. When the function is executed, the first argument ($$11) is the name of the command whose ar- guments are being completed, the second argument ($$22) is the word being completed, and the third argument ($$33) is - the word preceding the word being completed on the cur- + the word preceding the word being completed on the cur- rent command line. When _f_u_n_c_t_i_o_n finishes, programmable - completion retrieves the possible completions from the + completion retrieves the possible completions from the value of the CCOOMMPPRREEPPLLYY array variable. --GG _g_l_o_b_p_a_t - Expand the pathname expansion pattern _g_l_o_b_p_a_t to gener- + Expand the pathname expansion pattern _g_l_o_b_p_a_t to gener- ate the possible completions. --PP _p_r_e_f_i_x - Add _p_r_e_f_i_x to the beginning of each possible completion + Add _p_r_e_f_i_x to the beginning of each possible completion after all other options have been applied. --SS _s_u_f_f_i_x - Append _s_u_f_f_i_x to each possible completion after all + Append _s_u_f_f_i_x to each possible completion after all other options have been applied. --WW _w_o_r_d_l_i_s_t - Split the _w_o_r_d_l_i_s_t using the characters in the IIFFSS spe- - cial variable as delimiters, and expand each resulting - word. Shell quoting is honored within _w_o_r_d_l_i_s_t, in or- - der to provide a mechanism for the words to contain - shell metacharacters or characters in the value of IIFFSS. - The possible completions are the members of the resul- - tant list which match a prefix of the word being com- + Split the _w_o_r_d_l_i_s_t using the characters in the IIFFSS spe- + cial variable as delimiters, and expand each resulting + word. Shell quoting is honored within _w_o_r_d_l_i_s_t, in or- + der to provide a mechanism for the words to contain + shell metacharacters or characters in the value of IIFFSS. + The possible completions are the members of the resul- + tant list which match a prefix of the word being com- pleted. --XX _f_i_l_t_e_r_p_a_t - _f_i_l_t_e_r_p_a_t is a pattern as used for pathname expansion. + _f_i_l_t_e_r_p_a_t is a pattern as used for pathname expansion. It is applied to the list of possible completions gener- - ated by the preceding options and arguments, and each - completion matching _f_i_l_t_e_r_p_a_t is removed from the list. - A leading !! in _f_i_l_t_e_r_p_a_t negates the pattern; in this + ated by the preceding options and arguments, and each + completion matching _f_i_l_t_e_r_p_a_t is removed from the list. + A leading !! in _f_i_l_t_e_r_p_a_t negates the pattern; in this case, any completion not matching _f_i_l_t_e_r_p_a_t is removed. - The return value is true unless an invalid option is supplied, + The return value is true unless an invalid option is supplied, an option other than --pp, --rr, --DD, --EE, or --II is supplied without a - _n_a_m_e argument, an attempt is made to remove a completion speci- + _n_a_m_e argument, an attempt is made to remove a completion speci- fication for a _n_a_m_e for which no specification exists, or an er- ror occurs adding a completion specification. ccoommppoopptt [--oo _o_p_t_i_o_n] [--DDEEII] [++oo _o_p_t_i_o_n] [_n_a_m_e] - Modify completion options for each _n_a_m_e according to the _o_p_- + Modify completion options for each _n_a_m_e according to the _o_p_- _t_i_o_ns, or for the currently-executing completion if no _n_a_m_es are - supplied. If no _o_p_t_i_o_ns are supplied, display the completion - options for each _n_a_m_e or the current completion. The possible - values of _o_p_t_i_o_n are those valid for the ccoommpplleettee builtin de- + supplied. If no _o_p_t_i_o_ns are supplied, display the completion + options for each _n_a_m_e or the current completion. The possible + values of _o_p_t_i_o_n are those valid for the ccoommpplleettee builtin de- scribed above. The --DD option indicates that other supplied options should apply - to the "default" command completion; the --EE option indicates + to the "default" command completion; the --EE option indicates that other supplied options should apply to "empty" command com- pletion; and the --II option indicates that other supplied options - should apply to completion on the initial word on the line. + should apply to completion on the initial word on the line. These are determined in the same way as the ccoommpplleettee builtin. If multiple options are supplied, the --DD option takes precedence over --EE, and both take precedence over --II. - The return value is true unless an invalid option is supplied, + The return value is true unless an invalid option is supplied, an attempt is made to modify the options for a _n_a_m_e for which no completion specification exists, or an output error occurs. ccoonnttiinnuuee [_n] ccoonnttiinnuuee resumes the next iteration of the enclosing ffoorr, wwhhiillee, - uunnttiill, or sseelleecctt loop. If _n is specified, bbaasshh resumes the _nth - enclosing loop. _n must be >= 1. If _n is greater than the num- - ber of enclosing loops, the shell resumes the last enclosing - loop (the "top-level" loop). The return value is 0 unless _n is + uunnttiill, or sseelleecctt loop. If _n is specified, bbaasshh resumes the _nth + enclosing loop. _n must be >= 1. If _n is greater than the num- + ber of enclosing loops, the shell resumes the last enclosing + loop (the "top-level" loop). The return value is 0 unless _n is not greater than or equal to 1. ddeeccllaarree [--aaAAffFFggiiIIllnnrrttuuxx] [--pp] [_n_a_m_e[=_v_a_l_u_e] ...] ttyyppeesseett [--aaAAffFFggiiIIllnnrrttuuxx] [--pp] [_n_a_m_e[=_v_a_l_u_e] ...] - Declare variables and/or give them attributes. If no _n_a_m_es are + Declare variables and/or give them attributes. If no _n_a_m_es are given then display the values of variables or functions. The --pp - option will display the attributes and values of each _n_a_m_e. - When --pp is used with _n_a_m_e arguments, additional options, other + option will display the attributes and values of each _n_a_m_e. + When --pp is used with _n_a_m_e arguments, additional options, other than --ff and --FF, are ignored. When --pp is supplied without _n_a_m_e arguments, ddeeccllaarree will display the attributes and values of all variables having the attributes - specified by the additional options. If no other options are + specified by the additional options. If no other options are supplied with --pp, ddeeccllaarree will display the attributes and values - of all shell variables. The --ff option restricts the display to + of all shell variables. The --ff option restricts the display to shell functions. The --FF option inhibits the display of function definitions; only - the function name and attributes are printed. If the eexxttddeebbuugg - shell option is enabled using sshhoopptt, the source file name and - line number where each _n_a_m_e is defined are displayed as well. + the function name and attributes are printed. If the eexxttddeebbuugg + shell option is enabled using sshhoopptt, the source file name and + line number where each _n_a_m_e is defined are displayed as well. The --FF option implies --ff. - The --gg option forces variables to be created or modified at the + The --gg option forces variables to be created or modified at the global scope, even when ddeeccllaarree is executed in a shell function. It is ignored when ddeeccllaarree is not executed in a shell function. - The --II option causes local variables to inherit the attributes - (except the _n_a_m_e_r_e_f attribute) and value of any existing vari- - able with the same _n_a_m_e at a surrounding scope. If there is no + The --II option causes local variables to inherit the attributes + (except the _n_a_m_e_r_e_f attribute) and value of any existing vari- + able with the same _n_a_m_e at a surrounding scope. If there is no existing variable, the local variable is initially unset. - The following options can be used to restrict output to vari- - ables with the specified attribute or to give variables attrib- + The following options can be used to restrict output to vari- + ables with the specified attribute or to give variables attrib- utes: - --aa Each _n_a_m_e is an indexed array variable (see AArrrraayyss + --aa Each _n_a_m_e is an indexed array variable (see AArrrraayyss above). - --AA Each _n_a_m_e is an associative array variable (see AArrrraayyss + --AA Each _n_a_m_e is an associative array variable (see AArrrraayyss above). --ff Each _n_a_m_e refers to a shell function. --ii The variable is treated as an integer; arithmetic evalua- - tion (see AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN above) is performed when + tion (see AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN above) is performed when the variable is assigned a value. - --ll When the variable is assigned a value, all upper-case - characters are converted to lower-case. The upper-case + --ll When the variable is assigned a value, all upper-case + characters are converted to lower-case. The upper-case attribute is disabled. - --nn Give each _n_a_m_e the _n_a_m_e_r_e_f attribute, making it a name - reference to another variable. That other variable is - defined by the value of _n_a_m_e. All references, assign- - ments, and attribute modifications to _n_a_m_e, except those - using or changing the --nn attribute itself, are performed - on the variable referenced by _n_a_m_e's value. The nameref + --nn Give each _n_a_m_e the _n_a_m_e_r_e_f attribute, making it a name + reference to another variable. That other variable is + defined by the value of _n_a_m_e. All references, assign- + ments, and attribute modifications to _n_a_m_e, except those + using or changing the --nn attribute itself, are performed + on the variable referenced by _n_a_m_e's value. The nameref attribute cannot be applied to array variables. --rr Make _n_a_m_es readonly. These names cannot then be assigned values by subsequent assignment statements or unset. --tt Give each _n_a_m_e the _t_r_a_c_e attribute. Traced functions in- - herit the DDEEBBUUGG and RREETTUURRNN traps from the calling shell. + herit the DDEEBBUUGG and RREETTUURRNN traps from the calling shell. The trace attribute has no special meaning for variables. - --uu When the variable is assigned a value, all lower-case - characters are converted to upper-case. The lower-case + --uu When the variable is assigned a value, all lower-case + characters are converted to upper-case. The lower-case attribute is disabled. - --xx Mark each _n_a_m_e for export to subsequent commands via the + --xx Mark each _n_a_m_e for export to subsequent commands via the environment. - Using "+" instead of "-" turns off the specified attribute in- + Using "+" instead of "-" turns off the specified attribute in- stead, with the exceptions that ++aa and ++AA may not be used to de- - stroy array variables and ++rr will not remove the readonly at- + stroy array variables and ++rr will not remove the readonly at- tribute. - When used in a function, ddeeccllaarree and ttyyppeesseett make each _n_a_m_e lo- - cal, as with the llooccaall command, unless the --gg option is sup- - plied. If a variable name is followed by =_v_a_l_u_e, the value of - the variable is set to _v_a_l_u_e. When using --aa or --AA and the com- - pound assignment syntax to create array variables, additional + When used in a function, ddeeccllaarree and ttyyppeesseett make each _n_a_m_e lo- + cal, as with the llooccaall command, unless the --gg option is sup- + plied. If a variable name is followed by =_v_a_l_u_e, the value of + the variable is set to _v_a_l_u_e. When using --aa or --AA and the com- + pound assignment syntax to create array variables, additional attributes do not take effect until subsequent assignments. - The return value is 0 unless an invalid option is encountered, - an attempt is made to define a function using "-f foo=bar", an + The return value is 0 unless an invalid option is encountered, + an attempt is made to define a function using "-f foo=bar", an attempt is made to assign a value to a readonly variable, an at- tempt is made to assign a value to an array variable without us- - ing the compound assignment syntax (see AArrrraayyss above), one of + ing the compound assignment syntax (see AArrrraayyss above), one of the _n_a_m_e_s 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 + 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 --ff. ddiirrss [[--ccllppvv]] [[++_n]] [[--_n]] Without options, display the list of currently remembered direc- - tories. The default display is on a single line with directory - names separated by spaces. Directories are added to the list - with the ppuusshhdd command; the ppooppdd command removes entries from - the list. The current directory is always the first directory + tories. The default display is on a single line with directory + names separated by spaces. Directories are added to the list + with the ppuusshhdd command; the ppooppdd command removes entries from + the list. The current directory is always the first directory in the stack. Options, if supplied, have the following meanings: - --cc Clears the directory stack by deleting all of the en- + --cc Clears the directory stack by deleting all of the en- tries. - --ll Produces a listing using full pathnames; the default + --ll Produces a listing using full pathnames; the default listing format uses a tilde to denote the home directory. --pp Print the directory stack with one entry per line. - --vv Print the directory stack with one entry per line, pre- + --vv Print the directory stack with one entry per line, pre- fixing each entry with its index in the stack. ++_n Displays the _nth entry counting from the left of the list shown by ddiirrss when invoked without options, starting with zero. - --_n Displays the _nth entry counting from the right of the + --_n Displays the _nth entry counting from the right of the list shown by ddiirrss when invoked without options, starting with zero. - The return value is 0 unless an invalid option is supplied or _n + The return value is 0 unless an invalid option is supplied or _n indexes beyond the end of the directory stack. ddiissoowwnn [--aarr] [--hh] [_i_d ...] - Without options, remove each _i_d from the table of active jobs. - Each _i_d may be a job specification _j_o_b_s_p_e_c or a process ID _p_i_d; + Without options, remove each _i_d from the table of active jobs. + Each _i_d may be a job specification _j_o_b_s_p_e_c or a process ID _p_i_d; if _i_d is a _p_i_d, ddiissoowwnn uses the job containing _p_i_d as _j_o_b_s_p_e_c. - If the --hh option is supplied, ddiissoowwnn does not remove the jobs - corresponding to each _i_d from the jobs table, but rather marks - them so the shell does not send SSIIGGHHUUPP to the job if the shell + If the --hh option is supplied, ddiissoowwnn does not remove the jobs + corresponding to each _i_d from the jobs table, but rather marks + them so the shell does not send SSIIGGHHUUPP to the job if the shell receives a SSIIGGHHUUPP. - If no _i_d is supplied, the --aa option means to remove or mark all + If no _i_d is supplied, the --aa option means to remove or mark all jobs; the --rr option without an _i_d argument removes or marks run- - ning jobs. If no _i_d is supplied, and neither the --aa nor the --rr + ning jobs. If no _i_d is supplied, and neither the --aa nor the --rr option is supplied, ddiissoowwnn removes or marks the current job. The return value is 0 unless an _i_d does not specify a valid job. eecchhoo [--nneeEE] [_a_r_g ...] - Output the _a_r_gs, separated by spaces, followed by a newline. - The return status is 0 unless a write error occurs. If --nn is + Output the _a_r_gs, separated by spaces, followed by a newline. + The return status is 0 unless a write error occurs. If --nn is specified, the trailing newline is not printed. - If the --ee option is given, eecchhoo interprets the following back- + If the --ee option is given, eecchhoo interprets the following back- slash-escaped characters. The --EE option disables interpretation - of these escape characters, even on systems where they are in- - terpreted by default. The xxppgg__eecchhoo shell option determines + of these escape characters, even on systems where they are in- + terpreted by default. The xxppgg__eecchhoo shell option determines whether or not eecchhoo interprets any options and expands these es- - cape characters. eecchhoo does not interpret ---- to mean the end of + cape characters. eecchhoo does not interpret ---- to mean the end of options. eecchhoo interprets the following escape sequences: @@ -5672,103 +5695,103 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS \\tt horizontal tab \\vv vertical tab \\\\ backslash - \\00_n_n_n The eight-bit character whose value is the octal value + \\00_n_n_n The eight-bit character whose value is the octal value _n_n_n (zero to three octal digits). - \\xx_H_H The eight-bit character whose value is the hexadecimal + \\xx_H_H The eight-bit character whose value is the hexadecimal value _H_H (one or two hex digits). - \\uu_H_H_H_H The Unicode (ISO/IEC 10646) character whose value is the + \\uu_H_H_H_H The Unicode (ISO/IEC 10646) character whose value is the hexadecimal value _H_H_H_H (one to four hex digits). \\UU_H_H_H_H_H_H_H_H - The Unicode (ISO/IEC 10646) character whose value is the + The Unicode (ISO/IEC 10646) character whose value is the hexadecimal value _H_H_H_H_H_H_H_H (one to eight hex digits). - eecchhoo writes any unrecognized backslash-escaped characters un- + eecchhoo writes any unrecognized backslash-escaped characters un- changed. eennaabbllee [--aa] [--ddnnppss] [--ff _f_i_l_e_n_a_m_e] [_n_a_m_e ...] - Enable and disable builtin shell commands. Disabling a builtin - allows an executable file which has the same name as a shell - builtin to be executed without specifying a full pathname, even + Enable and disable builtin shell commands. Disabling a builtin + allows an executable file 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 files. - If --nn is supplied, each _n_a_m_e is disabled; otherwise, _n_a_m_es are - enabled. For example, to use the tteesstt binary found using PPAATTHH + If --nn is supplied, each _n_a_m_e is disabled; otherwise, _n_a_m_es are + enabled. For example, to use the tteesstt binary found using PPAATTHH instead of the shell builtin version, run "enable -n test". - If no _n_a_m_e arguments are supplied, or if the --pp option is sup- + If no _n_a_m_e arguments are supplied, or if the --pp option is sup- plied, print a list of shell builtins. With no other option ar- guments, the list consists of all enabled shell builtins. If --nn - is supplied, print only disabled builtins. If --aa is supplied, - the list printed includes all builtins, with an indication of + is supplied, print only disabled builtins. If --aa is supplied, + the list printed includes all builtins, with an indication of whether or not each is enabled. The --ss option means to restrict the output to the POSIX _s_p_e_c_i_a_l builtins. - The --ff option means to load the new builtin command _n_a_m_e from + The --ff option means to load the new builtin command _n_a_m_e from shared object _f_i_l_e_n_a_m_e, on systems that support dynamic loading. If _f_i_l_e_n_a_m_e does not contain a slash, BBaasshh will use the value of - the BBAASSHH__LLOOAADDAABBLLEESS__PPAATTHH variable as a colon-separated list of - directories in which to search for _f_i_l_e_n_a_m_e. The default for - BBAASSHH__LLOOAADDAABBLLEESS__PPAATTHH is system-dependent, and may include "." to - force a search of the current directory. The --dd option will - delete a builtin previously loaded with --ff. If _-_s is used with + the BBAASSHH__LLOOAADDAABBLLEESS__PPAATTHH variable as a colon-separated list of + directories in which to search for _f_i_l_e_n_a_m_e. The default for + BBAASSHH__LLOOAADDAABBLLEESS__PPAATTHH is system-dependent, and may include "." to + force a search of the current directory. The --dd option will + delete a builtin previously loaded with --ff. If _-_s is used with _-_f, the new builtin becomes a POSIX special builtin. - If no options are supplied and a _n_a_m_e is not a shell builtin, - eennaabbllee will attempt to load _n_a_m_e from a shared object named + If no options are supplied and a _n_a_m_e is not a shell builtin, + eennaabbllee will attempt to load _n_a_m_e from a shared object named _n_a_m_e, as if the command were "enable -f _n_a_m_e _n_a_m_e". - The return value is 0 unless a _n_a_m_e is not a shell builtin or + The return value is 0 unless a _n_a_m_e is not a shell builtin or there is an error loading a new builtin from a shared object. eevvaall [_a_r_g ...] - Concatenate the _a_r_gs together into a single command, separating + Concatenate the _a_r_gs together into a single command, separating them with spaces. BBaasshh then reads and execute this command, and - returns its exit status as the return status of eevvaall. If there + returns its exit status as the return status of eevvaall. If there are no _a_r_g_s, or only null arguments, eevvaall returns 0. eexxeecc [--ccll] [--aa _n_a_m_e] [_c_o_m_m_a_n_d [_a_r_g_u_m_e_n_t_s]] - If _c_o_m_m_a_n_d is specified, it replaces the shell without creating - a new process. _c_o_m_m_a_n_d cannot be a shell builtin or function. + If _c_o_m_m_a_n_d is specified, it replaces the shell without creating + a new process. _c_o_m_m_a_n_d cannot be a shell builtin or function. The _a_r_g_u_m_e_n_t_s become the arguments to _c_o_m_m_a_n_d. If the --ll option is supplied, the shell places a dash at the beginning of the ze- - roth argument passed to _c_o_m_m_a_n_d. This is what _l_o_g_i_n(1) does. - The --cc option causes _c_o_m_m_a_n_d to be executed with an empty envi- + roth argument passed to _c_o_m_m_a_n_d. This is what _l_o_g_i_n(1) does. + The --cc option causes _c_o_m_m_a_n_d to be executed with an empty envi- ronment. If --aa is supplied, the shell passes _n_a_m_e as the zeroth argument to the executed command. If _c_o_m_m_a_n_d cannot be executed for some reason, a non-interactive - shell exits, unless the eexxeeccffaaiill shell option is enabled. In - that case, it returns a non-zero status. An interactive shell - returns a non-zero status if the file cannot be executed. A + shell exits, unless the eexxeeccffaaiill shell option is enabled. In + that case, it returns a non-zero status. An interactive shell + returns a non-zero status if the file cannot be executed. A subshell exits unconditionally if eexxeecc fails. If _c_o_m_m_a_n_d is not specified, any redirections take effect in the - current shell, and the return status is 0. If there is a redi- + current shell, and the return status is 0. If there is a redi- rection error, the return status is 1. eexxiitt [_n] - Cause the shell to exit with a status of _n. If _n is omitted, - the exit status is that of the last command executed. Any trap + Cause the shell to exit with a status of _n. If _n is omitted, + the exit status is that of the last command executed. Any trap on EEXXIITT is executed before the shell terminates. eexxppoorrtt [--ffnn] [_n_a_m_e[=_v_a_l_u_e]] ... eexxppoorrtt --pp [[--ff]] - The supplied _n_a_m_e_s are marked for automatic export to the envi- - ronment of subsequently executed commands. If the --ff option is + The supplied _n_a_m_e_s are marked for automatic export to the envi- + ronment of subsequently executed commands. If the --ff option is given, the _n_a_m_e_s refer to functions. - The --nn option unexports, or removes the export attribute, from - each _n_a_m_e. If no _n_a_m_e_s are given, or if only the --pp option is - supplied, eexxppoorrtt displays a list of names of all exported vari- + The --nn option unexports, or removes the export attribute, from + each _n_a_m_e. If no _n_a_m_e_s are given, or if only the --pp option is + supplied, eexxppoorrtt displays a list of names of all exported vari- ables on the standard output. Using --pp and --ff together displays - exported functions. The --pp option displays output in a form + exported functions. The --pp option displays output in a form that may be reused as input. - eexxppoorrtt allows the value of a variable to be set when it is ex- + eexxppoorrtt allows the value of a variable to be set when it is ex- ported or unexported by following the variable name with =_v_a_l_u_e. This sets the value of the variable to _v_a_l_u_e while modifying the - export attribute. eexxppoorrtt returns an exit status of 0 unless an - invalid option is encountered, one of the _n_a_m_e_s is not a valid + export attribute. eexxppoorrtt returns an exit status of 0 unless an + invalid option is encountered, one of the _n_a_m_e_s is not a valid shell variable name, or --ff is supplied with a _n_a_m_e that is not a function. @@ -5776,141 +5799,141 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS ffcc [--ee _e_n_a_m_e] [--llnnrr] [_f_i_r_s_t] [_l_a_s_t] ffcc --ss [_p_a_t=_r_e_p] [_c_m_d] - The first form selects a range of commands from _f_i_r_s_t to _l_a_s_t - from the history list and displays or edits and re-executes - them. _F_i_r_s_t and _l_a_s_t 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 + The first form selects a range of commands from _f_i_r_s_t to _l_a_s_t + from the history list and displays or edits and re-executes + them. _F_i_r_s_t and _l_a_s_t 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). When listing, a _f_i_r_s_t or _l_a_s_t of 0 is equivalent to -1 and -0 is equivalent to the current command (usually the ffcc command); oth- - erwise 0 is equivalent to -1 and -0 is invalid. If _l_a_s_t is not + erwise 0 is equivalent to -1 and -0 is invalid. If _l_a_s_t is not specified, it is set to the current command for listing (so that "fc -l -10" prints the last 10 commands) and to _f_i_r_s_t otherwise. If _f_i_r_s_t is not specified, it is set to the previous command for editing and -16 for listing. - If the --ll option is supplied, the commands are listed on the - standard output. The --nn option suppresses the command numbers + If the --ll option is supplied, the commands are listed on the + standard output. The --nn option suppresses the command numbers when listing. The --rr option reverses the order of the commands. - Otherwise, ffcc invokes the editor named by _e_n_a_m_e on a file con- - taining those commands. If _e_n_a_m_e is not supplied, ffcc uses the - value of the FFCCEEDDIITT variable, and the value of EEDDIITTOORR if FFCCEEDDIITT - is not set. If neither variable is set, ffcc uses _v_i_. When edit- - ing is complete, ffcc reads the file containing the edited com- + Otherwise, ffcc invokes the editor named by _e_n_a_m_e on a file con- + taining those commands. If _e_n_a_m_e is not supplied, ffcc uses the + value of the FFCCEEDDIITT variable, and the value of EEDDIITTOORR if FFCCEEDDIITT + is not set. If neither variable is set, ffcc uses _v_i_. When edit- + ing is complete, ffcc reads the file containing the edited com- mands and echoes and executes them. - In the second form, ffcc re-executes _c_o_m_m_a_n_d after replacing each - instance of _p_a_t with _r_e_p. _C_o_m_m_a_n_d is interpreted the same as + In the second form, ffcc re-executes _c_o_m_m_a_n_d after replacing each + instance of _p_a_t with _r_e_p. _C_o_m_m_a_n_d is interpreted the same as _f_i_r_s_t above. - A useful alias to use with ffcc is "r="fc -s"", so that typing "r + A useful alias to use with ffcc is "r="fc -s"", so that typing "r cc" runs the last command beginning with "cc" and typing "r" re- executes the last command. - If the first form is used, the return value is zero unless an - invalid option is encountered or _f_i_r_s_t or _l_a_s_t specify history - lines out of range. When editing and re-executing a file of + If the first form is used, the return value is zero unless an + invalid option is encountered or _f_i_r_s_t or _l_a_s_t specify history + lines out of range. When editing and re-executing a file of commands, the return value is the value of the last command exe- cuted or failure if an error occurs with the temporary file. If the second form is used, the return status is that of the re-ex- - ecuted command, unless _c_m_d does not specify a valid history en- + ecuted command, unless _c_m_d does not specify a valid history en- try, in which case ffcc returns a non-zero status. ffgg [_j_o_b_s_p_e_c] - Resume _j_o_b_s_p_e_c in the foreground, and make it the current job. - If _j_o_b_s_p_e_c is not present, ffgg uses the shell's notion of the - _c_u_r_r_e_n_t _j_o_b. The return value is that of the command placed - into the foreground, or failure if run when job control is dis- + Resume _j_o_b_s_p_e_c in the foreground, and make it the current job. + If _j_o_b_s_p_e_c is not present, ffgg uses the shell's notion of the + _c_u_r_r_e_n_t _j_o_b. The return value is that of the command placed + into the foreground, or failure if run when job control is dis- abled or, when run with job control enabled, if _j_o_b_s_p_e_c does not - specify a valid job or _j_o_b_s_p_e_c specifies a job that was started + specify a valid job or _j_o_b_s_p_e_c specifies a job that was started without job control. ggeettooppttss _o_p_t_s_t_r_i_n_g _n_a_m_e [_a_r_g ...] - ggeettooppttss is used by shell scripts and functions to parse posi- - tional parameters and obtain options and their arguments. _o_p_t_- - _s_t_r_i_n_g contains the option characters to be recognized; if a + ggeettooppttss is used by shell scripts and functions to parse posi- + tional parameters and obtain options and their arguments. _o_p_t_- + _s_t_r_i_n_g 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. + 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, ggeettooppttss places the next option in the + Each time it is invoked, ggeettooppttss places the next option in the shell variable _n_a_m_e, initializing _n_a_m_e if it does not exist, and the index of the next argument to be processed into the variable - OOPPTTIINNDD. OOPPTTIINNDD is initialized to 1 each time the shell or a - shell script is invoked. When an option requires an argument, + OOPPTTIINNDD. OOPPTTIINNDD is initialized to 1 each time the shell or a + shell script is invoked. When an option requires an argument, ggeettooppttss places that argument into the variable OOPPTTAARRGG. - The shell does not reset OOPPTTIINNDD automatically; it must be manu- - ally reset between multiple calls to ggeettooppttss within the same + The shell does not reset OOPPTTIINNDD automatically; it must be manu- + ally reset between multiple calls to ggeettooppttss within the same shell invocation to use a new set of parameters. - When it reaches the end of options, ggeettooppttss exits with a return - value greater than zero. OOPPTTIINNDD is set to the index of the + When it reaches the end of options, ggeettooppttss exits with a return + value greater than zero. OOPPTTIINNDD is set to the index of the first non-option argument, and _n_a_m_e is set to ?. - ggeettooppttss normally parses the positional parameters, but if more - arguments are supplied as _a_r_g values, ggeettooppttss parses those in- + ggeettooppttss normally parses the positional parameters, but if more + arguments are supplied as _a_r_g values, ggeettooppttss parses those in- stead. - ggeettooppttss can report errors in two ways. If the first character - of _o_p_t_s_t_r_i_n_g is a colon, ggeettooppttss uses _s_i_l_e_n_t error reporting. - In normal operation, ggeettooppttss prints diagnostic messages when it - encounters invalid options or missing option arguments. If the - variable OOPPTTEERRRR is set to 0, ggeettooppttss does not display any error - messages, even if the first character of _o_p_t_s_t_r_i_n_g is not a + ggeettooppttss can report errors in two ways. If the first character + of _o_p_t_s_t_r_i_n_g is a colon, ggeettooppttss uses _s_i_l_e_n_t error reporting. + In normal operation, ggeettooppttss prints diagnostic messages when it + encounters invalid options or missing option arguments. If the + variable OOPPTTEERRRR is set to 0, ggeettooppttss does not display any error + messages, even if the first character of _o_p_t_s_t_r_i_n_g is not a colon. If ggeettooppttss detects an invalid option, it places ? into _n_a_m_e and, - if not silent, prints an error message and unsets OOPPTTAARRGG. If - ggeettooppttss is silent, it assigns the option character found to OOPP-- + if not silent, prints an error message and unsets OOPPTTAARRGG. If + ggeettooppttss is silent, it assigns the option character found to OOPP-- TTAARRGG and does not print a diagnostic message. - If a required argument is not found, and ggeettooppttss is not silent, + If a required argument is not found, and ggeettooppttss is not silent, it sets the value of _n_a_m_e to a question mark (??), unsets OOPPTTAARRGG, - and prints a diagnostic message. If ggeettooppttss is silent, it sets - the value of _n_a_m_e to a colon (::) and sets OOPPTTAARRGG to the option + and prints a diagnostic message. If ggeettooppttss is silent, it sets + the value of _n_a_m_e to a colon (::) and sets OOPPTTAARRGG to the option character found. - ggeettooppttss returns true if an option, specified or unspecified, is + ggeettooppttss returns true if an option, specified or unspecified, is found. It returns false if the end of options is encountered or an error occurs. hhaasshh [--llrr] [--pp _f_i_l_e_n_a_m_e] [--ddtt] [_n_a_m_e] Each time hhaasshh is invoked, it remembers the full pathname of the - command _n_a_m_e as determined by searching the directories in - $$PPAATTHH. Any previously-remembered pathname associated with _n_a_m_e - is discarded. If the --pp option is supplied, hhaasshh uses _f_i_l_e_n_a_m_e + command _n_a_m_e as determined by searching the directories in + $$PPAATTHH. Any previously-remembered pathname associated with _n_a_m_e + is discarded. If the --pp option is supplied, hhaasshh uses _f_i_l_e_n_a_m_e as the full pathname of the command. - The --rr option causes the shell to forget all remembered loca- - tions. Assigning to the PPAATTHH variable also clears all hashed - filenames. The --dd option causes the shell to forget the remem- + The --rr option causes the shell to forget all remembered loca- + tions. Assigning to the PPAATTHH variable also clears all hashed + filenames. The --dd option causes the shell to forget the remem- bered location of each _n_a_m_e. If the --tt option is supplied, hhaasshh prints the full pathname cor- - responding to each _n_a_m_e. If multiple _n_a_m_e arguments are sup- - plied with --tt, hhaasshh prints the _n_a_m_e before the corresponding + responding to each _n_a_m_e. If multiple _n_a_m_e arguments are sup- + plied with --tt, hhaasshh prints the _n_a_m_e before the corresponding hashed full pathname. The --ll option displays output in a format that may be reused as input. - If no arguments are given, or if only --ll is supplied, hhaasshh - prints information about remembered commands. The --tt, --dd, and - --pp options (the options that act on the _n_a_m_e arguments) are mu- + If no arguments are given, or if only --ll is supplied, hhaasshh + prints information about remembered commands. The --tt, --dd, and + --pp options (the options that act on the _n_a_m_e arguments) are mu- tually exclusive. Only one will be active. If more than one is - supplied, --tt has higher priority than --pp, and both have higher + supplied, --tt has higher priority than --pp, and both have higher priority than --dd. - The return status is zero unless a _n_a_m_e is not found or an in- + The return status is zero unless a _n_a_m_e is not found or an in- valid option is supplied. hheellpp [--ddmmss] [_p_a_t_t_e_r_n] - Display helpful information about builtin commands. If _p_a_t_t_e_r_n - is specified, hheellpp gives detailed help on all commands matching - _p_a_t_t_e_r_n as described below; otherwise it displays a list of all + Display helpful information about builtin commands. If _p_a_t_t_e_r_n + is specified, hheellpp gives detailed help on all commands matching + _p_a_t_t_e_r_n as described below; otherwise it displays a list of all the builtins and shell compound commands. Options, if supplied, have the follow meanings: @@ -5920,13 +5943,13 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS format --ss Display only a short usage synopsis for each _p_a_t_t_e_r_n - If _p_a_t_t_e_r_n contains pattern matching characters (see PPaatttteerrnn - MMaattcchhiinngg above) it's treated as a shell pattern and hheellpp prints + If _p_a_t_t_e_r_n contains pattern matching characters (see PPaatttteerrnn + MMaattcchhiinngg above) it's treated as a shell pattern and hheellpp prints the description of each help topic matching _p_a_t_t_e_r_n. - If not, and _p_a_t_t_e_r_n exactly matches the name of a help topic, - hheellpp prints the description associated with that topic. Other- - wise, hheellpp performs prefix matching and prints the descriptions + If not, and _p_a_t_t_e_r_n exactly matches the name of a help topic, + hheellpp prints the description associated with that topic. Other- + wise, hheellpp performs prefix matching and prints the descriptions of all matching help topics. The return status is 0 unless no command matches _p_a_t_t_e_r_n. @@ -5938,18 +5961,18 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS hhiissttoorryy --aannrrww [_f_i_l_e_n_a_m_e] hhiissttoorryy --pp _a_r_g [_a_r_g ...] hhiissttoorryy --ss _a_r_g [_a_r_g ...] - With no options, display the command history list with numbers. - Entries prefixed with a ** have been modified. An argument of _n - lists only the last _n entries. If the shell variable HHIISSTTTTIIMMEE-- - FFOORRMMAATT is set and not null, it is used as a format string for - _s_t_r_f_t_i_m_e(3) to display the time stamp associated with each dis- - played history entry. If hhiissttoorryy uses HHIISSTTTTIIMMEEFFOORRMMAATT, it does - not print an intervening space between the formatted time stamp + With no options, display the command history list with numbers. + Entries prefixed with a ** have been modified. An argument of _n + lists only the last _n entries. If the shell variable HHIISSTTTTIIMMEE-- + FFOORRMMAATT is set and not null, it is used as a format string for + _s_t_r_f_t_i_m_e(3) to display the time stamp associated with each dis- + played history entry. If hhiissttoorryy uses HHIISSTTTTIIMMEEFFOORRMMAATT, it does + not print an intervening space between the formatted time stamp and the history entry. If _f_i_l_e_n_a_m_e is supplied, hhiissttoorryy uses it as the name of the his- - tory file; if not, it uses the value of HHIISSTTFFIILLEE. If _f_i_l_e_n_a_m_e - is not supplied and HHIISSTTFFIILLEE is unset or null, the --aa,, --nn,, --rr,, + tory file; if not, it uses the value of HHIISSTTFFIILLEE. If _f_i_l_e_n_a_m_e + is not supplied and HHIISSTTFFIILLEE is unset or null, the --aa,, --nn,, --rr,, and --ww options have no effect. Options, if supplied, have the following meanings: @@ -5957,20 +5980,20 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS can be used with the other options to replace the history list. --dd _o_f_f_s_e_t - Delete the history entry at position _o_f_f_s_e_t. If _o_f_f_s_e_t + Delete the history entry at position _o_f_f_s_e_t. If _o_f_f_s_e_t is negative, it is interpreted as relative to one greater than the last history position, so negative indices count - back from the end of the history, and an index of -1 + back from the end of the history, and an index of -1 refers to the current hhiissttoorryy --dd command. --dd _s_t_a_r_t-_e_n_d - Delete the range of history entries between positions - _s_t_a_r_t and _e_n_d, inclusive. Positive and negative values + Delete the range of history entries between positions + _s_t_a_r_t and _e_n_d, inclusive. Positive and negative values for _s_t_a_r_t and _e_n_d are interpreted as described above. - --aa Append the "new" history lines to the history file. - These are history lines entered since the beginning of + --aa Append the "new" history lines to the history file. + These are history lines entered since the beginning of the current bbaasshh session, but not already appended to the history file. - --nn Read the history lines not already read from the history + --nn Read the history lines not already read from the history file and add them to the current history list. These are lines appended to the history file since the beginning of the current bbaasshh session. @@ -5978,24 +6001,24 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS rent history list. --ww Write the current history list to the history file, over- writing the history file. - --pp Perform history substitution on the following _a_r_g_s and - display the result on the standard output, without stor- - ing the results in the history list. Each _a_r_g must be + --pp Perform history substitution on the following _a_r_g_s and + display the result on the standard output, without stor- + ing the results in the history list. Each _a_r_g must be quoted to disable normal history expansion. - --ss Store the _a_r_g_s in the history list as a single entry. - The last command in the history list is removed before + --ss Store the _a_r_g_s in the history list as a single entry. + The last command in the history list is removed before adding the _a_r_g_s. - If the HHIISSTTTTIIMMEEFFOORRMMAATT variable is set, hhiissttoorryy writes the time + If the HHIISSTTTTIIMMEEFFOORRMMAATT variable is set, hhiissttoorryy writes the time stamp information associated with each history entry to the his- - tory file, marked with the history comment character as de- - scribed above. When the history file is read, lines beginning - with the history comment character followed immediately by a - digit are interpreted as timestamps for the following history + tory file, marked with the history comment character as de- + scribed above. When the history file is read, lines beginning + with the history comment character followed immediately by a + digit are interpreted as timestamps for the following history entry. - The return value is 0 unless an invalid option is encountered, - an error occurs while reading or writing the history file, an + The return value is 0 unless an invalid option is encountered, + an error occurs while reading or writing the history file, an invalid _o_f_f_s_e_t or range is supplied as an argument to --dd, or the history expansion supplied as an argument to --pp fails. @@ -6004,14 +6027,14 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS The first form lists the active jobs. The options have the fol- lowing meanings: --ll List process IDs in addition to the normal information. - --nn Display information only about jobs that have changed + --nn Display information only about jobs that have changed status since the user was last notified of their status. - --pp List only the process ID of the job's process group + --pp List only the process ID of the job's process group leader. --rr Display only running jobs. --ss Display only stopped jobs. - If _j_o_b_s_p_e_c is supplied, jjoobbss restricts output to information + If _j_o_b_s_p_e_c is supplied, jjoobbss restricts output to information about that job. The return status is 0 unless an invalid option is encountered or an invalid _j_o_b_s_p_e_c is supplied. @@ -6021,433 +6044,433 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS kkiillll [--ss _s_i_g_s_p_e_c | --nn _s_i_g_n_u_m | --_s_i_g_s_p_e_c] _i_d [ ... ] kkiillll --ll|--LL [_s_i_g_s_p_e_c | _e_x_i_t___s_t_a_t_u_s] - Send the signal specified by _s_i_g_s_p_e_c or _s_i_g_n_u_m to the processes + Send the signal specified by _s_i_g_s_p_e_c or _s_i_g_n_u_m to the processes named by each _i_d. Each _i_d may be a job specification _j_o_b_s_p_e_c or - a process ID _p_i_d. _s_i_g_s_p_e_c is either a case-insensitive signal - name such as SSIIGGKKIILLLL (with or without the SSIIGG prefix) or a sig- - nal number; _s_i_g_n_u_m is a signal number. If _s_i_g_s_p_e_c is not sup- + a process ID _p_i_d. _s_i_g_s_p_e_c is either a case-insensitive signal + name such as SSIIGGKKIILLLL (with or without the SSIIGG prefix) or a sig- + nal number; _s_i_g_n_u_m is a signal number. If _s_i_g_s_p_e_c is not sup- plied, then kkiillll sends SSIIGGTTEERRMM. The --ll option lists the signal names. If any arguments are sup- plied when --ll is given, kkiillll lists the names of the signals cor- - responding to the arguments, and the return status is 0. The - _e_x_i_t___s_t_a_t_u_s argument to --ll is a number specifying either a sig- - nal number or the exit status of a process terminated by a sig- - nal; if it is supplied, kkiillll prints the name of the signal that + responding to the arguments, and the return status is 0. The + _e_x_i_t___s_t_a_t_u_s argument to --ll is a number specifying either a sig- + nal number or the exit status of a process terminated by a sig- + nal; if it is supplied, kkiillll prints the name of the signal that caused the process to terminate. kkiillll assumes that process exit statuses are greater than 128; anything less than that is a sig- nal number. The --LL option is equivalent to --ll. - kkiillll returns true if at least one signal was successfully sent, + kkiillll returns true if at least one signal was successfully sent, or false if an error occurs or an invalid option is encountered. lleett _a_r_g [_a_r_g ...] - Each _a_r_g is evaluated as an arithmetic expression (see AARRIITTHH-- - MMEETTIICC EEVVAALLUUAATTIIOONN above). If the last _a_r_g evaluates to 0, lleett + Each _a_r_g is evaluated as an arithmetic expression (see AARRIITTHH-- + MMEETTIICC EEVVAALLUUAATTIIOONN above). If the last _a_r_g evaluates to 0, lleett returns 1; otherwise lleett returns 0. llooccaall [_o_p_t_i_o_n] [_n_a_m_e[=_v_a_l_u_e] ... | - ] For each argument, create a local variable named _n_a_m_e and assign - it _v_a_l_u_e. The _o_p_t_i_o_n can be any of the options accepted by ddee-- - ccllaarree. When llooccaall is used within a function, it causes the - variable _n_a_m_e to have a visible scope restricted to that func- - tion and its children. It is an error to use llooccaall when not + it _v_a_l_u_e. The _o_p_t_i_o_n can be any of the options accepted by ddee-- + ccllaarree. When llooccaall is used within a function, it causes the + variable _n_a_m_e to have a visible scope restricted to that func- + tion and its children. It is an error to use llooccaall when not within a function. - If _n_a_m_e is -, it makes the set of shell options local to the - function in which llooccaall is invoked: any shell options changed - using the sseett builtin inside the function after the call to lloo-- - ccaall are restored to their original values when the function re- - turns. The restore is performed as if a series of sseett commands - were executed to restore the values that were in place before + If _n_a_m_e is -, it makes the set of shell options local to the + function in which llooccaall is invoked: any shell options changed + using the sseett builtin inside the function after the call to lloo-- + ccaall are restored to their original values when the function re- + turns. The restore is performed as if a series of sseett commands + were executed to restore the values that were in place before the function. - With no operands, llooccaall writes a list of local variables to the + With no operands, llooccaall writes a list of local variables to the standard output. - The return status is 0 unless llooccaall is used outside a function, + The return status is 0 unless llooccaall is used outside a function, an invalid _n_a_m_e is supplied, or _n_a_m_e is a readonly variable. llooggoouutt [[_n]] - Exit a login shell, returning a status of _n to the shell's par- + Exit a login shell, returning a status of _n to the shell's par- ent. mmaappffiillee [--dd _d_e_l_i_m] [--nn _c_o_u_n_t] [--OO _o_r_i_g_i_n] [--ss _c_o_u_n_t] [--tt] [--uu _f_d] [--CC _c_a_l_l_b_a_c_k] [--cc _q_u_a_n_t_u_m] [_a_r_r_a_y] rreeaaddaarrrraayy [--dd _d_e_l_i_m] [--nn _c_o_u_n_t] [--OO _o_r_i_g_i_n] [--ss _c_o_u_n_t] [--tt] [--uu _f_d] [--CC _c_a_l_l_b_a_c_k] [--cc _q_u_a_n_t_u_m] [_a_r_r_a_y] - Read lines from the standard input, or from file descriptor _f_d - if the --uu option is supplied, into the indexed array variable - _a_r_r_a_y. The variable MMAAPPFFIILLEE is the default _a_r_r_a_y. Options, if + Read lines from the standard input, or from file descriptor _f_d + if the --uu option is supplied, into the indexed array variable + _a_r_r_a_y. The variable MMAAPPFFIILLEE is the default _a_r_r_a_y. Options, if supplied, have the following meanings: - --dd Use the first character of _d_e_l_i_m to terminate each input + --dd Use the first character of _d_e_l_i_m to terminate each input line, rather than newline. If _d_e_l_i_m is the empty string, mmaappffiillee will terminate a line when it reads a NUL charac- ter. --nn Copy at most _c_o_u_n_t lines. If _c_o_u_n_t is 0, copy all lines. - --OO Begin assigning to _a_r_r_a_y at index _o_r_i_g_i_n. The default + --OO Begin assigning to _a_r_r_a_y at index _o_r_i_g_i_n. The default index is 0. --ss Discard the first _c_o_u_n_t lines read. - --tt Remove a trailing _d_e_l_i_m (default newline) from each line + --tt Remove a trailing _d_e_l_i_m (default newline) from each line read. - --uu Read lines from file descriptor _f_d instead of the stan- + --uu Read lines from file descriptor _f_d instead of the stan- dard input. - --CC Evaluate _c_a_l_l_b_a_c_k each time _q_u_a_n_t_u_m lines are read. The + --CC Evaluate _c_a_l_l_b_a_c_k each time _q_u_a_n_t_u_m lines are read. The --cc option specifies _q_u_a_n_t_u_m. - --cc Specify the number of lines read between each call to + --cc Specify the number of lines read between each call to _c_a_l_l_b_a_c_k. - If --CC is specified without --cc, the default quantum is 5000. + If --CC is specified without --cc, the default quantum is 5000. When _c_a_l_l_b_a_c_k 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. _c_a_l_l_b_a_c_k is evaluated after + element as additional arguments. _c_a_l_l_b_a_c_k is evaluated after the line is read but before the array element is assigned. - If not supplied with an explicit origin, mmaappffiillee will clear _a_r_- + If not supplied with an explicit origin, mmaappffiillee will clear _a_r_- _r_a_y before assigning to it. mmaappffiillee returns zero unless an invalid option or option argument - is supplied, _a_r_r_a_y is invalid or unassignable, or if _a_r_r_a_y is + is supplied, _a_r_r_a_y is invalid or unassignable, or if _a_r_r_a_y is not an indexed array. ppooppdd [-nn] [+_n] [-_n] - Remove entries from the directory stack. The elements are num- - bered from 0 starting at the first directory listed by ddiirrss, so - ppooppdd is equivalent to "popd +0." With no arguments, ppooppdd re- - moves the top directory from the stack, and changes to the new + Remove entries from the directory stack. The elements are num- + bered from 0 starting at the first directory listed by ddiirrss, so + ppooppdd is equivalent to "popd +0." With no arguments, ppooppdd re- + moves the top directory from the stack, and changes to the new top directory. Arguments, if supplied, have the following mean- ings: --nn Suppress the normal change of directory when removing di- rectories from the stack, only manipulate the stack. - ++_n Remove the _nth entry counting from the left of the list - shown by ddiirrss, starting with zero, from the stack. For + ++_n Remove the _nth entry counting from the left of the list + shown by ddiirrss, starting with zero, from the stack. For example: "popd +0" removes the first directory, "popd +1" the second. - --_n Remove the _nth entry counting from the right of the list - shown by ddiirrss, starting with zero. For example: "popd - -0" removes the last directory, "popd -1" the next to + --_n Remove the _nth entry counting from the right of the list + shown by ddiirrss, starting with zero. For example: "popd + -0" removes the last directory, "popd -1" the next to last. - If the top element of the directory stack is modified, and the - _-_n option was not supplied, ppooppdd uses the ccdd builtin to change + If the top element of the directory stack is modified, and the + _-_n option was not supplied, ppooppdd uses the ccdd builtin to change to the directory at the top of the stack. If the ccdd fails, ppooppdd returns a non-zero value. - Otherwise, ppooppdd returns false if an invalid option is supplied, - the directory stack is empty, or _n specifies a non-existent di- + Otherwise, ppooppdd returns false if an invalid option is supplied, + the directory stack is empty, or _n specifies a non-existent di- rectory stack entry. - If the ppooppdd command is successful, bbaasshh runs ddiirrss to show the - final contents of the directory stack, and the return status is + If the ppooppdd command is successful, bbaasshh runs ddiirrss to show the + final contents of the directory stack, and the return status is 0. pprriinnttff [--vv _v_a_r] _f_o_r_m_a_t [_a_r_g_u_m_e_n_t_s] - Write the formatted _a_r_g_u_m_e_n_t_s to the standard output under the - control of the _f_o_r_m_a_t. The --vv option assigns the output to the + Write the formatted _a_r_g_u_m_e_n_t_s to the standard output under the + control of the _f_o_r_m_a_t. The --vv option assigns the output to the variable _v_a_r rather than printing it to the standard output. - The _f_o_r_m_a_t 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 _a_r_g_u_m_e_n_t. In - addition to the standard _p_r_i_n_t_f(3) format characters ccCCssSS-- + The _f_o_r_m_a_t 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 _a_r_g_u_m_e_n_t. In + addition to the standard _p_r_i_n_t_f(3) format characters ccCCssSS-- nnddiioouuxxXXeeEEffFFggGGaaAA, pprriinnttff interprets the following additional for- mat specifiers: %%bb causes pprriinnttff to expand backslash escape sequences in the corresponding _a_r_g_u_m_e_n_t in the same way as eecchhoo --ee. - %%qq causes pprriinnttff to output the corresponding _a_r_g_u_m_e_n_t in a - format that can be reused as shell input. %%qq and %%QQ use - the $$'''' quoting style if any characters in the argument - string require it, and backslash quoting otherwise. If - the format string uses the _p_r_i_n_t_f alternate form, these + %%qq causes pprriinnttff to output the corresponding _a_r_g_u_m_e_n_t in a + format that can be reused as shell input. %%qq and %%QQ use + the $$'''' quoting style if any characters in the argument + string require it, and backslash quoting otherwise. If + the format string uses the _p_r_i_n_t_f alternate form, these two formats quote the argument string using single quotes. - %%QQ like %%qq, but applies any supplied precision to the _a_r_g_u_- + %%QQ like %%qq, but applies any supplied precision to the _a_r_g_u_- _m_e_n_t before quoting it. %%((_d_a_t_e_f_m_t))TT - causes pprriinnttff to output the date-time string resulting - from using _d_a_t_e_f_m_t as a format string for _s_t_r_f_t_i_m_e(3). + causes pprriinnttff to output the date-time string resulting + from using _d_a_t_e_f_m_t as a format string for _s_t_r_f_t_i_m_e(3). The corresponding _a_r_g_u_m_e_n_t is an integer representing the number of seconds since the epoch. This format specifier recognizes two special argument values: -1 represents the - current time, and -2 represents the time the shell was + current time, and -2 represents the time the shell was invoked. If no argument is specified, conversion behaves - as if -1 had been supplied. This is an exception to the + as if -1 had been supplied. This is an exception to the usual pprriinnttff behavior. The %b, %q, and %T format specifiers all use the field width and precision arguments from the format specification and write that - many bytes from (or use that wide a field for) the expanded ar- - gument, which usually contains more characters than the origi- + many bytes from (or use that wide a field for) the expanded ar- + gument, which usually contains more characters than the origi- nal. The %n format specifier accepts a corresponding argument that is treated as a shell variable name. - The %s and %c format specifiers accept an l (long) modifier, + The %s and %c format specifiers accept an l (long) modifier, which forces them to convert the argument string to a wide-char- acter string and apply any supplied field width and precision in terms of characters, not bytes. The %S and %C format specifiers are equivalent to %ls and %lc, respectively. - Arguments to non-string format specifiers are treated as C con- + Arguments to non-string format specifiers are treated as C con- stants, 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 numeric value of the following character, using the cur- + if the leading character is a single or double quote, the value + is the numeric value of the following character, using the cur- rent locale. - The _f_o_r_m_a_t is reused as necessary to consume all of the _a_r_g_u_- + The _f_o_r_m_a_t is reused as necessary to consume all of the _a_r_g_u_- _m_e_n_t_s. If the _f_o_r_m_a_t requires more _a_r_g_u_m_e_n_t_s 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 if an invalid option is sup- + 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 if an invalid option is sup- plied or a write or assignment error occurs. ppuusshhdd [--nn] [+_n] [-_n] ppuusshhdd [--nn] [_d_i_r] Add a directory to the top of the directory stack, or rotate the - stack, making the new top of the stack the current working di- - rectory. With no arguments, ppuusshhdd exchanges the top two ele- - ments of the directory stack. Arguments, if supplied, have the + stack, making the new top of the stack the current working di- + rectory. With no arguments, ppuusshhdd exchanges the top two ele- + ments of the directory stack. Arguments, if supplied, have the following meanings: - --nn Suppress the normal change of directory when rotating or - adding directories to the stack, only manipulate the + --nn Suppress the normal change of directory when rotating or + adding directories to the stack, only manipulate the stack. ++_n Rotate the stack so that the _nth directory (counting from - the left of the list shown by ddiirrss, starting with zero) + the left of the list shown by ddiirrss, starting with zero) is at the top. - --_n Rotates the stack so that the _nth directory (counting - from the right of the list shown by ddiirrss, starting with + --_n Rotates the stack so that the _nth directory (counting + from the right of the list shown by ddiirrss, starting with zero) is at the top. _d_i_r Adds _d_i_r to the directory stack at the top. After the stack has been modified, if the --nn option was not sup- - plied, ppuusshhdd uses the ccdd builtin to change to the directory at + plied, ppuusshhdd uses the ccdd builtin to change to the directory at the top of the stack. If the ccdd fails, ppuusshhdd returns a non-zero value. - Otherwise, if no arguments are supplied, ppuusshhdd returns zero un- - less the directory stack is empty. When rotating the directory + Otherwise, if no arguments are supplied, ppuusshhdd returns zero un- + less the directory stack is empty. When rotating the directory stack, ppuusshhdd returns zero unless the directory stack is empty or _n specifies a non-existent directory stack element. - If the ppuusshhdd command is successful, bbaasshh runs ddiirrss to show the + If the ppuusshhdd command is successful, bbaasshh runs ddiirrss to show the final contents of the directory stack. ppwwdd [--LLPP] - Print the absolute pathname of the current working directory. + Print the absolute pathname of the current working directory. The pathname printed contains no symbolic links if the --PP option is supplied or the --oo pphhyyssiiccaall option to the sseett builtin command - is enabled. If the --LL option is used, the pathname printed may - contain symbolic links. The return status is 0 unless an error + is enabled. If the --LL 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 in- valid option is supplied. rreeaadd [--EEeerrss] [--aa _a_n_a_m_e] [--dd _d_e_l_i_m] [--ii _t_e_x_t] [--nn _n_c_h_a_r_s] [--NN _n_c_h_a_r_s] [--pp _p_r_o_m_p_t] [--tt _t_i_m_e_o_u_t] [--uu _f_d] [_n_a_m_e ...] Read one line from the standard input, or from the file descrip- - tor _f_d supplied as an argument to the --uu option, split it into - words as described above under WWoorrdd SSpplliittttiinngg, and assign the - first word to the first _n_a_m_e, the second word to the second - _n_a_m_e, and so on. If there are more words than names, the re- - maining words and their intervening delimiters are assigned to - the last _n_a_m_e. If there are fewer words read from the input - stream than names, the remaining names are assigned empty val- - ues. The characters in the value of the IIFFSS variable are used + tor _f_d supplied as an argument to the --uu option, split it into + words as described above under WWoorrdd SSpplliittttiinngg, and assign the + first word to the first _n_a_m_e, the second word to the second + _n_a_m_e, and so on. If there are more words than names, the re- + maining words and their intervening delimiters are assigned to + the last _n_a_m_e. If there are fewer words read from the input + stream than names, the remaining names are assigned empty val- + ues. The characters in the value of the IIFFSS variable are used to split the line into words using the same rules the shell uses for expansion (described above under WWoorrdd SSpplliittttiinngg). The back- - slash character (\\) removes any special meaning for the next + slash character (\\) removes any special meaning for the next character read and is used for line continuation. Options, if supplied, have the following meanings: --aa _a_n_a_m_e The words are assigned to sequential indices of the array variable _a_n_a_m_e, starting at 0. _a_n_a_m_e is unset before any - new values are assigned. Other _n_a_m_e arguments are ig- + new values are assigned. Other _n_a_m_e arguments are ig- nored. --dd _d_e_l_i_m - The first character of _d_e_l_i_m terminates the input line, - rather than newline. If _d_e_l_i_m is the empty string, rreeaadd + The first character of _d_e_l_i_m terminates the input line, + rather than newline. If _d_e_l_i_m is the empty string, rreeaadd will terminate a line when it reads a NUL character. - --ee If the standard input is coming from a terminal, rreeaadd - uses rreeaaddlliinnee (see RREEAADDLLIINNEE above) to obtain the line. - RReeaaddlliinnee uses the current (or default, if line editing - was not previously active) editing settings, but uses + --ee If the standard input is coming from a terminal, rreeaadd + uses rreeaaddlliinnee (see RREEAADDLLIINNEE above) to obtain the line. + RReeaaddlliinnee uses the current (or default, if line editing + was not previously active) editing settings, but uses rreeaaddlliinnee's default filename completion. - --EE If the standard input is coming from a terminal, rreeaadd - uses rreeaaddlliinnee (see RREEAADDLLIINNEE above) to obtain the line. - RReeaaddlliinnee uses the current (or default, if line editing - was not previously active) editing settings, but uses + --EE If the standard input is coming from a terminal, rreeaadd + uses rreeaaddlliinnee (see RREEAADDLLIINNEE above) to obtain the line. + RReeaaddlliinnee uses the current (or default, if line editing + was not previously active) editing settings, but uses bash's default completion, including programmable comple- tion. --ii _t_e_x_t - If rreeaaddlliinnee is being used to read the line, rreeaadd places + If rreeaaddlliinnee is being used to read the line, rreeaadd places _t_e_x_t into the editing buffer before editing begins. --nn _n_c_h_a_r_s - rreeaadd returns after reading _n_c_h_a_r_s characters rather than - waiting for a complete line of input, unless it encoun- - ters EOF or rreeaadd times out, but honors a delimiter if it + rreeaadd returns after reading _n_c_h_a_r_s characters rather than + waiting for a complete line of input, unless it encoun- + ters EOF or rreeaadd times out, but honors a delimiter if it reads fewer than _n_c_h_a_r_s characters before the delimiter. --NN _n_c_h_a_r_s - rreeaadd returns after reading exactly _n_c_h_a_r_s characters - rather than waiting for a complete line of input, unless + rreeaadd returns after reading exactly _n_c_h_a_r_s characters + rather than waiting for a complete line of input, unless it encounters EOF or rreeaadd times out. Any delimiter char- - acters in the input are not treated specially and do not + acters in the input are not treated specially and do not cause rreeaadd to return until it has read _n_c_h_a_r_s characters. The result is not split on the characters in IIFFSS; the in- tent is that the variable is assigned exactly the charac- - ters read (with the exception of backslash; see the --rr + ters read (with the exception of backslash; see the --rr option below). --pp _p_r_o_m_p_t Display _p_r_o_m_p_t on standard error, without a trailing new- - line, before attempting to read any input, but only if + line, before attempting to read any input, but only if input is coming from a terminal. --rr Backslash does not act as an escape character. The back- - slash is considered to be part of the line. In particu- - lar, a backslash-newline pair may not then be used as a + slash is considered to be part of the line. In particu- + lar, a backslash-newline pair may not then be used as a line continuation. --ss Silent mode. If input is coming from a terminal, charac- ters are not echoed. --tt _t_i_m_e_o_u_t - Cause rreeaadd to time out and return failure if it does not - read a complete line of input (or a specified number of - characters) within _t_i_m_e_o_u_t seconds. _t_i_m_e_o_u_t may be a - decimal number with a fractional portion following the - decimal point. This option is only effective if rreeaadd is - reading input from a terminal, pipe, or other special - file; it has no effect when reading from regular files. - If rreeaadd times out, it saves any partial input read into - the specified variable _n_a_m_e, and the exit status is - greater than 128. If _t_i_m_e_o_u_t is 0, rreeaadd returns immedi- - ately, without trying to read any data. In this case, - the exit status is 0 if input is available on the speci- - fied file descriptor, or the read will return EOF, non- + Cause rreeaadd to time out and return failure if it does not + read a complete line of input (or a specified number of + characters) within _t_i_m_e_o_u_t seconds. _t_i_m_e_o_u_t may be a + decimal number with a fractional portion following the + decimal point. This option is only effective if rreeaadd is + reading input from a terminal, pipe, or other special + file; it has no effect when reading from regular files. + If rreeaadd times out, it saves any partial input read into + the specified variable _n_a_m_e, and the exit status is + greater than 128. If _t_i_m_e_o_u_t is 0, rreeaadd returns immedi- + ately, without trying to read any data. In this case, + the exit status is 0 if input is available on the speci- + fied file descriptor, or the read will return EOF, non- zero otherwise. - --uu _f_d Read input from file descriptor _f_d instead of the stan- + --uu _f_d Read input from file descriptor _f_d instead of the stan- dard input. - Other than the case where _d_e_l_i_m is the empty string, rreeaadd ig- + Other than the case where _d_e_l_i_m is the empty string, rreeaadd ig- nores any NUL characters in the input. - If no _n_a_m_e_s are supplied, rreeaadd assigns the line read, without - the ending delimiter but otherwise unmodified, to the variable + If no _n_a_m_e_s are supplied, rreeaadd assigns the line read, without + the ending delimiter but otherwise unmodified, to the variable RREEPPLLYY. The exit status is zero, unless end-of-file is encountered, rreeaadd - times out (in which case the status is greater than 128), a + times out (in which case the status is greater than 128), a variable assignment error (such as assigning to a readonly vari- - able) occurs, or an invalid file descriptor is supplied as the + able) occurs, or an invalid file descriptor is supplied as the argument to --uu. rreeaaddoonnllyy [--aaAAff] [--pp] [_n_a_m_e[=_w_o_r_d] ...] - The given _n_a_m_e_s are marked readonly; the values of these _n_a_m_e_s + The given _n_a_m_e_s are marked readonly; the values of these _n_a_m_e_s may not be changed by subsequent assignment or unset. If the --ff - option is supplied, each _n_a_m_e refers to a shell function. The - --aa option restricts the variables to indexed arrays; the --AA op- + option is supplied, each _n_a_m_e refers to a shell function. The + --aa option restricts the variables to indexed arrays; the --AA op- tion restricts the variables to associative arrays. If both op- - tions are supplied, --AA takes precedence. If no _n_a_m_e arguments - are supplied, or if the --pp option is supplied, print a list of - all readonly names. The other options may be used to restrict + tions are supplied, --AA takes precedence. If no _n_a_m_e arguments + are supplied, or if the --pp option is supplied, print a list of + all readonly names. The other options may be used to restrict the output to a subset of the set of readonly names. The --pp op- tion displays output in a format that may be reused as input. - rreeaaddoonnllyy allows the value of a variable to be set at the same + rreeaaddoonnllyy allows the value of a variable to be set at the same time the readonly attribute is changed by following the variable - name with =_v_a_l_u_e. This sets the value of the variable is to + name with =_v_a_l_u_e. This sets the value of the variable is to _v_a_l_u_e while modifying the readonly attribute. - The return status is 0 unless an invalid option is encountered, - one of the _n_a_m_e_s is not a valid shell variable name, or --ff is + The return status is 0 unless an invalid option is encountered, + one of the _n_a_m_e_s is not a valid shell variable name, or --ff is supplied with a _n_a_m_e that is not a function. rreettuurrnn [_n] - Stop executing a shell function or sourced file and return the + Stop executing a shell function or sourced file and return the value specified by _n to its caller. If _n is omitted, the return - status is that of the last command executed. If rreettuurrnn is exe- - cuted by a trap handler, the last command used to determine the + status is that of the last command executed. If rreettuurrnn is exe- + cuted by a trap handler, the last command used to determine the status is the last command executed before the trap handler. If rreettuurrnn is executed during a DDEEBBUUGG trap, the last command used to - determine the status is the last command executed by the trap + determine the status is the last command executed by the trap handler before rreettuurrnn was invoked. When rreettuurrnn is used to terminate execution of a script being ex- - ecuted by the .. (ssoouurrccee) command, it causes the shell to stop - executing that script and return either _n or the exit status of - the last command executed within the script as the exit status - of the script. If _n is supplied, the return value is its least + ecuted by the .. (ssoouurrccee) command, it causes the shell to stop + executing that script and return either _n or the exit status of + the last command executed within the script as the exit status + of the script. If _n is supplied, the return value is its least significant 8 bits. - Any command associated with the RREETTUURRNN trap is executed before + Any command associated with the RREETTUURRNN trap is executed before execution resumes after the function or script. - The return status is non-zero if rreettuurrnn is supplied a non-nu- + The return status is non-zero if rreettuurrnn is supplied a non-nu- meric argument, or is used outside a function and not during ex- ecution of a script by .. or ssoouurrccee. sseett [--aabbeeffhhkkmmnnppttuuvvxxBBCCEEHHPPTT] [--oo _o_p_t_i_o_n_-_n_a_m_e] [----] [--] [_a_r_g ...] sseett [++aabbeeffhhkkmmnnppttuuvvxxBBCCEEHHPPTT] [++oo _o_p_t_i_o_n_-_n_a_m_e] [----] [--] [_a_r_g ...] sseett --oo - sseett ++oo Without options, display the name and value of each shell vari- - able in a format that can be reused as input for setting or re- + sseett ++oo Without options, display the name and value of each shell vari- + able in a format that can be reused as input for setting or re- setting the currently-set variables. Read-only variables cannot - be reset. In posix mode, 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 argu- - ments remaining after option processing are treated as values + be reset. In posix mode, 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 argu- + ments remaining after option processing are treated as values for the positional parameters and are assigned, in order, to $$11, - $$22, ..., $$_n. Options, if specified, have the following mean- + $$22, ..., $$_n. Options, if specified, have the following mean- ings: --aa Each variable or function that is created or modified is - given the export attribute and marked for export to the + given the export attribute and marked for export to the environment of subsequent commands. - --bb Report the status of terminated background jobs immedi- + --bb Report the status of terminated background jobs immedi- ately, rather than before the next primary prompt or af- - ter a foreground command terminates. This is effective + ter a foreground command terminates. This is effective only when job control is enabled. - --ee Exit immediately if a _p_i_p_e_l_i_n_e (which may consist of a - single _s_i_m_p_l_e _c_o_m_m_a_n_d), a _l_i_s_t, or a _c_o_m_p_o_u_n_d _c_o_m_m_a_n_d + --ee Exit immediately if a _p_i_p_e_l_i_n_e (which may consist of a + single _s_i_m_p_l_e _c_o_m_m_a_n_d), a _l_i_s_t, or a _c_o_m_p_o_u_n_d _c_o_m_m_a_n_d (see SSHHEELLLL GGRRAAMMMMAARR 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 wwhhiillee - or uunnttiill reserved word, part of the test following the - iiff or eelliiff reserved words, part of any command executed - in a &&&& or |||| list except the command following the fi- - nal &&&& or ||||, any command in a pipeline but the last - (subject to the state of the ppiippeeffaaiill shell option), or - if the command's return value is being inverted with !!. - If a compound command other than a subshell returns a - non-zero status because a command failed while --ee was - being ignored, the shell does not exit. A trap on EERRRR, + The shell does not exit if the command that fails is + part of the command list immediately following a wwhhiillee + or uunnttiill reserved word, part of the test following the + iiff or eelliiff reserved words, part of any command executed + in a &&&& or |||| list except the command following the fi- + nal &&&& or ||||, any command in a pipeline but the last + (subject to the state of the ppiippeeffaaiill shell option), or + if the command's return value is being inverted with !!. + If a compound command other than a subshell returns a + non-zero status because a command failed while --ee was + being ignored, the shell does not exit. A trap on EERRRR, if set, is executed before the shell exits. This option applies to the shell environment and each subshell envi- - ronment separately (see CCOOMMMMAANNDD EEXXEECCUUTTIIOONN EENNVVIIRROONNMMEENNTT + ronment separately (see CCOOMMMMAANNDD EEXXEECCUUTTIIOONN EENNVVIIRROONNMMEENNTT above), and may cause subshells to exit before executing all the commands in the subshell. - If a compound command or shell function executes in a - context where --ee is being ignored, none of the commands - executed within the compound command or function body - will be affected by the --ee setting, even if --ee is set - and a command returns a failure status. If a compound - command or shell function sets --ee while executing in a - context where --ee is ignored, that setting will not have - any effect until the compound command or the command + If a compound command or shell function executes in a + context where --ee is being ignored, none of the commands + executed within the compound command or function body + will be affected by the --ee setting, even if --ee is set + and a command returns a failure status. If a compound + command or shell function sets --ee while executing in a + context where --ee is ignored, that setting will not have + any effect until the compound command or the command containing the function call completes. --ff Disable pathname expansion. - --hh Remember the location of commands as they are looked up + --hh Remember the location of commands as they are looked up for execution. This is enabled by default. - --kk All arguments in the form of assignment statements are - placed in the environment for a command, not just those + --kk All arguments in the form of assignment statements are + placed in the environment for a command, not just those that precede the command name. - --mm Monitor mode. Job control is enabled. This option is - on by default for interactive shells on systems that - support it (see JJOOBB CCOONNTTRROOLL above). All processes run + --mm Monitor mode. Job control is enabled. This option is + on by default for interactive shells on systems that + support it (see JJOOBB CCOONNTTRROOLL above). All processes run in a separate process group. When a background job com- pletes, the shell prints a line containing its exit sta- tus. --nn Read commands but do not execute them. This may be used - to check a shell script for syntax errors. This is ig- + to check a shell script for syntax errors. This is ig- nored by interactive shells. --oo _o_p_t_i_o_n_-_n_a_m_e The _o_p_t_i_o_n_-_n_a_m_e can be one of the following: @@ -6455,10 +6478,10 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS Same as --aa. bbrraacceeeexxppaanndd Same as --BB. - eemmaaccss Use an emacs-style command line editing inter- + eemmaaccss Use an emacs-style command line editing inter- face. This is enabled by default when the shell is interactive, unless the shell is started with - the ----nnooeeddiittiinngg option. This also affects the + the ----nnooeeddiittiinngg option. This also affects the editing interface used for rreeaadd --ee. eerrrreexxiitt Same as --ee. eerrrrttrraaccee @@ -6472,7 +6495,7 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS HHIISSTTOORRYY. This option is on by default in inter- active shells. iiggnnoorreeeeooff - The effect is as if the shell command + The effect is as if the shell command "IGNOREEOF=10" had been executed (see SShheellll VVaarriiaabblleess above). kkeeyywwoorrdd Same as --kk. @@ -6488,184 +6511,184 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS pphhyyssiiccaall Same as --PP. ppiippeeffaaiill - 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 + 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. - ppoossiixx Enable posix mode; change the behavior of bbaasshh - where the default operation differs from the - POSIX standard to match the standard. See SSEEEE - AALLSSOO below for a reference to a document that + ppoossiixx Enable posix mode; change the behavior of bbaasshh + where the default operation differs from the + POSIX standard to match the standard. See SSEEEE + AALLSSOO below for a reference to a document that details how posix mode affects bash's behavior. pprriivviilleeggeedd Same as --pp. vveerrbboossee Same as --vv. - vvii Use a vi-style command line editing interface. + vvii Use a vi-style command line editing interface. This also affects the editing interface used for rreeaadd --ee. xxttrraaccee Same as --xx. - If --oo is supplied with no _o_p_t_i_o_n_-_n_a_m_e, sseett prints the - current shell option settings. If ++oo is supplied with - no _o_p_t_i_o_n_-_n_a_m_e, sseett prints a series of sseett commands to - recreate the current option settings on the standard + If --oo is supplied with no _o_p_t_i_o_n_-_n_a_m_e, sseett prints the + current shell option settings. If ++oo is supplied with + no _o_p_t_i_o_n_-_n_a_m_e, sseett prints a series of sseett commands to + recreate the current option settings on the standard output. - --pp Turn on _p_r_i_v_i_l_e_g_e_d mode. In this mode, the shell does - not read the $$EENNVV and $$BBAASSHH__EENNVV files, shell functions - are not inherited from the environment, and the SSHHEELL-- - LLOOPPTTSS, BBAASSHHOOPPTTSS, CCDDPPAATTHH, and GGLLOOBBIIGGNNOORREE variables, if - they appear in the environment, are ignored. If the - shell is started with the effective user (group) id not - equal to the real user (group) id, and the --pp option is - not supplied, these actions are taken and the effective + --pp Turn on _p_r_i_v_i_l_e_g_e_d mode. In this mode, the shell does + not read the $$EENNVV and $$BBAASSHH__EENNVV files, shell functions + are not inherited from the environment, and the SSHHEELL-- + LLOOPPTTSS, BBAASSHHOOPPTTSS, CCDDPPAATTHH, and GGLLOOBBIIGGNNOORREE 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 --pp option is + not supplied, these actions are taken and the effective user id is set to the real user id. If the --pp option is supplied at startup, the effective user id is not reset. - Turning this option off causes the effective user and + Turning this option off causes the effective user and group ids to be set to the real user and group ids. --rr Enable restricted shell mode. This option cannot be un- set once it has been set. --tt Exit after reading and executing one command. --uu Treat unset variables and parameters other than the spe- - cial parameters "@" and "*", or array variables sub- - scripted with "@" or "*", 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 + cial parameters "@" and "*", or array variables sub- + scripted with "@" or "*", 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. --vv Print shell input lines as they are read. - --xx After expanding each _s_i_m_p_l_e _c_o_m_m_a_n_d, ffoorr command, ccaassee + --xx After expanding each _s_i_m_p_l_e _c_o_m_m_a_n_d, ffoorr command, ccaassee command, sseelleecctt command, or arithmetic ffoorr command, dis- - play the expanded value of PPSS44, followed by the command - and its expanded arguments or associated word list, to + play the expanded value of PPSS44, followed by the command + and its expanded arguments or associated word list, to the standard error. - --BB The shell performs brace expansion (see BBrraaccee EExxppaannssiioonn + --BB The shell performs brace expansion (see BBrraaccee EExxppaannssiioonn above). This is on by default. - --CC If set, bbaasshh does not overwrite an existing file with - the >>, >>&&, and <<>> redirection operators. Using the - redirection operator >>|| instead of >> will override this + --CC If set, bbaasshh does not overwrite an existing file with + the >>, >>&&, and <<>> redirection operators. Using the + redirection operator >>|| instead of >> will override this and force the creation of an output file. --EE If set, any trap on EERRRR is inherited by shell functions, - command substitutions, and commands executed in a sub- - shell environment. The EERRRR trap is normally not inher- + command substitutions, and commands executed in a sub- + shell environment. The EERRRR trap is normally not inher- ited in such cases. --HH Enable !! style history substitution. This option is on by default when the shell is interactive. - --PP If set, the shell does not resolve symbolic links when - executing commands such as ccdd that change the current + --PP If set, the shell does not resolve symbolic links when + executing commands such as ccdd that change the current working directory. It uses the physical directory structure instead. By default, bbaasshh follows the logical - chain of directories when performing commands which + chain of directories when performing commands which change the current directory. - --TT If set, any traps on DDEEBBUUGG and RREETTUURRNN are inherited by + --TT If set, any traps on DDEEBBUUGG and RREETTUURRNN are inherited by shell functions, command substitutions, and commands ex- - ecuted in a subshell environment. The DDEEBBUUGG and RREETTUURRNN + ecuted in a subshell environment. The DDEEBBUUGG and RREETTUURRNN traps are normally not inherited in such cases. ---- If no arguments follow this option, unset the positional parameters. Otherwise, set the positional parameters to the _a_r_gs, even if some of them begin with a --. -- Signal the end of options, and assign all remaining _a_r_gs to the positional parameters. The --xx and --vv options are - turned off. If there are no _a_r_gs, the positional para- + turned off. If there are no _a_r_gs, the positional para- meters remain unchanged. - The options are off by default unless otherwise noted. Using + - rather than - causes these options to be turned off. The op- + The options are off by default unless otherwise noted. Using + + rather than - causes these options to be turned off. The op- tions can also be specified as arguments to an invocation of the - shell. The current set of options may be found in $$--. The re- - turn status is always zero unless an invalid option is encoun- + shell. The current set of options may be found in $$--. The re- + turn status is always zero unless an invalid option is encoun- tered. sshhiifftt [_n] Rename positional parameters from _n+1 ... to $$11 ........ Parameters - represented by the numbers $$## down to $$##-_n+1 are unset. _n must - be a non-negative number less than or equal to $$##. If _n is 0, - no parameters are changed. If _n is not given, it is assumed to - be 1. If _n is greater than $$##, the positional parameters are - not changed. The return status is greater than zero if _n is + represented by the numbers $$## down to $$##-_n+1 are unset. _n must + be a non-negative number less than or equal to $$##. If _n is 0, + no parameters are changed. If _n is not given, it is assumed to + be 1. If _n is greater than $$##, the positional parameters are + not changed. The return status is greater than zero if _n is greater than $$## or less than zero; otherwise 0. sshhoopptt [--ppqqssuu] [--oo] [_o_p_t_n_a_m_e ...] - Toggle the values of settings controlling optional shell behav- - ior. The settings can be either those listed below, or, if the + Toggle the values of settings controlling optional shell behav- + ior. The settings can be either those listed below, or, if the --oo option is used, those available with the --oo option to the sseett builtin command. - With no options, or with the --pp option, display a list of all - settable options, with an indication of whether or not each is - set; if any _o_p_t_n_a_m_e_s are supplied, the output is restricted to + With no options, or with the --pp option, display a list of all + settable options, with an indication of whether or not each is + set; if any _o_p_t_n_a_m_e_s are supplied, the output is restricted to those options. The --pp option displays output in a form that may be reused as input. Other options have the following meanings: --ss Enable (set) each _o_p_t_n_a_m_e. --uu Disable (unset) each _o_p_t_n_a_m_e. - --qq Suppresses normal output (quiet mode); the return status + --qq Suppresses normal output (quiet mode); the return status indicates whether the _o_p_t_n_a_m_e is set or unset. If multi- - ple _o_p_t_n_a_m_e arguments are supplied with --qq, the return + ple _o_p_t_n_a_m_e arguments are supplied with --qq, the return status is zero if all _o_p_t_n_a_m_e_s are enabled; non-zero oth- erwise. - --oo Restricts the values of _o_p_t_n_a_m_e to be those defined for + --oo Restricts the values of _o_p_t_n_a_m_e to be those defined for the --oo option to the sseett builtin. - If either --ss or --uu is used with no _o_p_t_n_a_m_e arguments, sshhoopptt - shows only those options which are set or unset, respectively. - Unless otherwise noted, the sshhoopptt options are disabled (unset) + If either --ss or --uu is used with no _o_p_t_n_a_m_e arguments, sshhoopptt + shows only those options which are set or unset, respectively. + Unless otherwise noted, the sshhoopptt options are disabled (unset) by default. - The return status when listing options is zero if all _o_p_t_n_a_m_e_s - are enabled, non-zero otherwise. When setting or unsetting op- - tions, the return status is zero unless an _o_p_t_n_a_m_e is not a + The return status when listing options is zero if all _o_p_t_n_a_m_e_s + are enabled, non-zero otherwise. When setting or unsetting op- + tions, the return status is zero unless an _o_p_t_n_a_m_e is not a valid shell option. The list of sshhoopptt options is: aarrrraayy__eexxppaanndd__oonnccee - If set, the shell suppresses multiple evaluation of as- + If set, the shell suppresses multiple evaluation of as- sociative and indexed array subscripts during arithmetic expression evaluation, while executing builtins that can - perform variable assignments, and while executing + perform variable assignments, and while executing builtins that perform array dereferencing. aassssoocc__eexxppaanndd__oonnccee Deprecated; a synonym for aarrrraayy__eexxppaanndd__oonnccee. - aauuttooccdd If set, a command name that is the name of a directory - is executed as if it were the argument to the ccdd com- + aauuttooccdd If set, a command name that is the name of a directory + is executed as if it were the argument to the ccdd com- mand. This option is only used by interactive shells. bbaasshh__ssoouurrccee__ffuullllppaatthh - If set, filenames added to the BBAASSHH__SSOOUURRCCEE array vari- - able are converted to full pathnames (see SShheellll VVaarrii-- + If set, filenames added to the BBAASSHH__SSOOUURRCCEE array vari- + able are converted to full pathnames (see SShheellll VVaarrii-- aabblleess above). ccddaabbllee__vvaarrss - If set, an argument to the ccdd builtin command that is - not a directory is assumed to be the name of a variable + If set, an argument to the ccdd builtin command that is + not a directory is assumed to be the name of a variable whose value is the directory to change to. - ccddssppeellll If set, the ccdd command attempts to correct minor errors - in the spelling of a directory component. Minor errors - include transposed characters, a missing character, and + ccddssppeellll If set, the ccdd command attempts to correct minor errors + in the spelling of a directory component. Minor errors + include transposed characters, a missing character, and one extra character. If ccdd corrects the directory name, - it prints the corrected filename, and the command pro- + it prints the corrected filename, and the command pro- ceeds. This option is only used by interactive shells. cchheecckkhhaasshh If set, bbaasshh checks that a command found in the hash ta- - ble exists before trying to execute it. If a hashed - command no longer exists, bbaasshh performs a normal path + ble exists before trying to execute it. If a hashed + command no longer exists, bbaasshh performs a normal path search. cchheecckkjjoobbss If set, bbaasshh lists the status of any stopped and running - jobs before exiting an interactive shell. If any jobs + jobs before exiting an interactive shell. If any jobs are running, bbaasshh defers the exit until a second exit is - attempted without an intervening command (see JJOOBB CCOONN-- - TTRROOLL above). The shell always postpones exiting if any + attempted without an intervening command (see JJOOBB CCOONN-- + TTRROOLL above). The shell always postpones exiting if any jobs are stopped. cchheecckkwwiinnssiizzee - If set, bbaasshh checks the window size after each external - (non-builtin) command and, if necessary, updates the - values of LLIINNEESS and CCOOLLUUMMNNSS, using the file descriptor - associated with the standard error if it is a terminal. + If set, bbaasshh checks the window size after each external + (non-builtin) command and, if necessary, updates the + values of LLIINNEESS and CCOOLLUUMMNNSS, using the file descriptor + associated with the standard error if it is a terminal. This option is enabled by default. - ccmmddhhiisstt If set, bbaasshh attempts to save all lines of a multiple- - line command in the same history entry. This allows - easy re-editing of multi-line commands. This option is - enabled by default, but only has an effect if command + ccmmddhhiisstt If set, bbaasshh attempts to save all lines of a multiple- + line command in the same history entry. This allows + easy re-editing of multi-line commands. This option is + enabled by default, but only has an effect if command history is enabled, as described above under HHIISSTTOORRYY. ccoommppaatt3311 ccoommppaatt3322 @@ -6674,143 +6697,143 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS ccoommppaatt4422 ccoommppaatt4433 ccoommppaatt4444 - These control aspects of the shell's compatibility mode + These control aspects of the shell's compatibility mode (see SSHHEELLLL CCOOMMPPAATTIIBBIILLIITTYY MMOODDEE below). ccoommpplleettee__ffuullllqquuoottee - If set, bbaasshh quotes all shell metacharacters in file- - names and directory names when performing completion. + If set, bbaasshh quotes all shell metacharacters in file- + names and directory names when performing completion. If not set, bbaasshh removes metacharacters such as the dol- - lar sign from the set of characters that will be quoted - in completed filenames when these metacharacters appear - in shell variable references in words to be completed. - This means that dollar signs in variable names that ex- - pand to directories will not be quoted; however, any - dollar signs appearing in filenames will not be quoted, - either. This is active only when bash is using back- - slashes to quote completed filenames. This variable is - set by default, which is the default bash behavior in + lar sign from the set of characters that will be quoted + in completed filenames when these metacharacters appear + in shell variable references in words to be completed. + This means that dollar signs in variable names that ex- + pand to directories will not be quoted; however, any + dollar signs appearing in filenames will not be quoted, + either. This is active only when bash is using back- + slashes to quote completed filenames. This variable is + set by default, which is the default bash behavior in versions through 4.2. ddiirreexxppaanndd - If set, bbaasshh replaces directory names with the results - of word expansion when performing filename completion. + If set, bbaasshh replaces directory names with the results + of word expansion when performing filename completion. This changes the contents of the rreeaaddlliinnee editing - buffer. If not set, bbaasshh attempts to preserve what the + buffer. If not set, bbaasshh attempts to preserve what the user typed. ddiirrssppeellll - If set, bbaasshh attempts spelling correction on directory - names during word completion if the directory name ini- + If set, bbaasshh attempts spelling correction on directory + names during word completion if the directory name ini- tially supplied does not exist. - ddoottgglloobb If set, bbaasshh includes filenames beginning with a "." in - the results of pathname expansion. The filenames _. and + ddoottgglloobb If set, bbaasshh includes filenames beginning with a "." in + the results of pathname expansion. The filenames _. and _._. must always be matched explicitly, even if ddoottgglloobb is set. eexxeeccffaaiill If set, a non-interactive shell will not exit if it can- - not execute the file specified as an argument to the - eexxeecc builtin. An interactive shell does not exit if + not execute the file specified as an argument to the + eexxeecc builtin. An interactive shell does not exit if eexxeecc fails. eexxppaanndd__aalliiaasseess - If set, aliases are expanded as described above under + If set, aliases are expanded as described above under AALLIIAASSEESS. This option is enabled by default for interac- tive shells. eexxttddeebbuugg - If set at shell invocation, or in a shell startup file, + If set at shell invocation, or in a shell startup file, arrange to execute the debugger profile before the shell - starts, identical to the ----ddeebbuuggggeerr option. If set af- - ter invocation, behavior intended for use by debuggers + starts, identical to the ----ddeebbuuggggeerr option. If set af- + ter invocation, behavior intended for use by debuggers is enabled: 11.. The --FF option to the ddeeccllaarree builtin displays the source file name and line number corresponding to each function name supplied as an argument. - 22.. If the command run by the DDEEBBUUGG trap returns a - non-zero value, the next command is skipped and + 22.. If the command run by the DDEEBBUUGG trap returns a + non-zero value, the next command is skipped and not executed. - 33.. If the command run by the DDEEBBUUGG trap returns a - value of 2, and the shell is executing in a sub- - routine (a shell function or a shell script exe- - cuted by the .. or ssoouurrccee builtins), the shell + 33.. If the command run by the DDEEBBUUGG trap returns a + value of 2, and the shell is executing in a sub- + routine (a shell function or a shell script exe- + cuted by the .. or ssoouurrccee builtins), the shell simulates a call to rreettuurrnn. - 44.. BBAASSHH__AARRGGCC and BBAASSHH__AARRGGVV are updated as described + 44.. BBAASSHH__AARRGGCC and BBAASSHH__AARRGGVV are updated as described in their descriptions above). - 55.. Function tracing is enabled: command substitu- + 55.. Function tracing is enabled: command substitu- tion, shell functions, and subshells invoked with (( _c_o_m_m_a_n_d )) inherit the DDEEBBUUGG and RREETTUURRNN traps. - 66.. Error tracing is enabled: command substitution, - shell functions, and subshells invoked with (( + 66.. Error tracing is enabled: command substitution, + shell functions, and subshells invoked with (( _c_o_m_m_a_n_d )) inherit the EERRRR trap. - eexxttgglloobb If set, enable the extended pattern matching features + eexxttgglloobb If set, enable the extended pattern matching features described above under PPaatthhnnaammee EExxppaannssiioonn. eexxttqquuoottee - If set, $$'_s_t_r_i_n_g' and $$"_s_t_r_i_n_g" quoting is performed - within $${{_p_a_r_a_m_e_t_e_r}} expansions enclosed in double + If set, $$'_s_t_r_i_n_g' and $$"_s_t_r_i_n_g" quoting is performed + within $${{_p_a_r_a_m_e_t_e_r}} expansions enclosed in double quotes. This option is enabled by default. ffaaiillgglloobb - If set, patterns which fail to match filenames during + If set, patterns which fail to match filenames during pathname expansion result in an expansion error. ffoorrccee__ffiiggnnoorree - If set, the suffixes specified by the FFIIGGNNOORREE shell - variable cause words to be ignored when performing word + If set, the suffixes specified by the FFIIGGNNOORREE shell + variable cause words to be ignored when performing word completion even if the ignored words are the only possi- - ble completions. See SShheellll VVaarriiaabblleess above for a de- - scription of FFIIGGNNOORREE. This option is enabled by de- + ble completions. See SShheellll VVaarriiaabblleess above for a de- + scription of FFIIGGNNOORREE. This option is enabled by de- fault. gglloobbaasscciiiirraannggeess - If set, range expressions used in pattern matching - bracket expressions (see PPaatttteerrnn MMaattcchhiinngg above) behave - as if in the traditional C locale when performing com- - parisons. That is, pattern matching does not take the - current locale's collating sequence into account, so bb - will not collate between AA and BB, and upper-case and + If set, range expressions used in pattern matching + bracket expressions (see PPaatttteerrnn MMaattcchhiinngg above) behave + as if in the traditional C locale when performing com- + parisons. That is, pattern matching does not take the + current locale's collating sequence into account, so bb + will not collate between AA and BB, and upper-case and lower-case ASCII characters will collate together. gglloobbsskkiippddoottss - If set, pathname expansion will never match the file- - names _. and _._., even if the pattern begins with a ".". + If set, pathname expansion will never match the file- + names _. and _._., even if the pattern begins with a ".". This option is enabled by default. gglloobbssttaarr If set, the pattern **** used in a pathname expansion con- - text will match all files and zero or more directories - and subdirectories. If the pattern is followed by a //, + text will match all files and zero or more directories + and subdirectories. If the pattern is followed by a //, only directories and subdirectories match. ggnnuu__eerrrrffmmtt If set, shell error messages are written in the standard GNU error message format. hhiissttaappppeenndd - If set, the history list is appended to the file named + If set, the history list is appended to the file named by the value of the HHIISSTTFFIILLEE variable when the shell ex- its, rather than overwriting the file. hhiissttrreeeeddiitt - If set, and rreeaaddlliinnee is being used, the user is given - the opportunity to re-edit a failed history substitu- + If set, and rreeaaddlliinnee is being used, the user is given + the opportunity to re-edit a failed history substitu- tion. hhiissttvveerriiffyy - If set, and rreeaaddlliinnee is being used, the results of his- - tory substitution are not immediately passed to the - shell parser. Instead, the resulting line is loaded + If set, and rreeaaddlliinnee is being used, the results of his- + tory substitution are not immediately passed to the + shell parser. Instead, the resulting line is loaded into the rreeaaddlliinnee editing buffer, allowing further modi- fication. hhoossttccoommpplleettee If set, and rreeaaddlliinnee is being used, bbaasshh will attempt to - perform hostname completion when a word containing a @@ - is being completed (see CCoommpplleettiinngg under RREEAADDLLIINNEE + perform hostname completion when a word containing a @@ + is being completed (see CCoommpplleettiinngg under RREEAADDLLIINNEE above). This is enabled by default. hhuuppoonneexxiitt If set, bbaasshh will send SSIIGGHHUUPP to all jobs when an inter- active login shell exits. iinnhheerriitt__eerrrreexxiitt - If set, command substitution inherits the value of the - eerrrreexxiitt option, instead of unsetting it in the subshell - environment. This option is enabled when posix mode is + If set, command substitution inherits the value of the + eerrrreexxiitt option, instead of unsetting it in the subshell + environment. This option is enabled when posix mode is enabled. iinntteerraaccttiivvee__ccoommmmeennttss - In an interactive shell, a word beginning with ## causes - that word and all remaining characters on that line to - be ignored, as in a non-interactive shell (see CCOOMMMMEENNTTSS + In an interactive shell, a word beginning with ## causes + that word and all remaining characters on that line to + be ignored, as in a non-interactive shell (see CCOOMMMMEENNTTSS above). This option is enabled by default. llaassttppiippee - If set, and job control is not active, the shell runs + If set, and job control is not active, the shell runs the last command of a pipeline not executed in the back- ground in the current shell environment. - lliitthhiisstt If set, and the ccmmddhhiisstt option is enabled, multi-line + lliitthhiisstt If set, and the ccmmddhhiisstt option is enabled, multi-line commands are saved to the history with embedded newlines rather than using semicolon separators where possible. llooccaallvvaarr__iinnhheerriitt @@ -6819,37 +6842,37 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS scope before any new value is assigned. The nameref at- tribute is not inherited. llooccaallvvaarr__uunnsseett - If set, calling uunnsseett on local variables in previous - function scopes marks them so subsequent lookups find + If set, calling uunnsseett on local variables in previous + function scopes marks them so subsequent lookups find them unset until that function returns. This is identi- - cal to the behavior of unsetting local variables at the + cal to the behavior of unsetting local variables at the current function scope. llooggiinn__sshheellll - The shell sets this option if it is started as a login - shell (see IINNVVOOCCAATTIIOONN above). The value may not be + The shell sets this option if it is started as a login + shell (see IINNVVOOCCAATTIIOONN above). The value may not be changed. mmaaiillwwaarrnn - If set, and a file that bbaasshh is checking for mail has - been accessed since the last time it was checked, bbaasshh - displays the message "The mail in _m_a_i_l_f_i_l_e has been + If set, and a file that bbaasshh is checking for mail has + been accessed since the last time it was checked, bbaasshh + displays the message "The mail in _m_a_i_l_f_i_l_e has been read". nnoo__eemmppttyy__ccmmdd__ccoommpplleettiioonn If set, and rreeaaddlliinnee is being used, bbaasshh does not search - PPAATTHH for possible completions when completion is at- + PPAATTHH for possible completions when completion is at- tempted on an empty line. nnooccaasseegglloobb - If set, bbaasshh matches filenames in a case-insensitive + If set, bbaasshh matches filenames in a case-insensitive fashion when performing pathname expansion (see PPaatthhnnaammee EExxppaannssiioonn above). nnooccaasseemmaattcchh - If set, bbaasshh matches patterns in a case-insensitive + If set, bbaasshh matches patterns in a case-insensitive fashion when performing matching while executing ccaassee or [[[[ conditional commands, when performing pattern substi- - tution word expansions, or when filtering possible com- + tution word expansions, or when filtering possible com- pletions as part of programmable completion. nnooeexxppaanndd__ttrraannssllaattiioonn - If set, bbaasshh encloses the translated results of $$""..."" - quoting in single quotes instead of double quotes. If + If set, bbaasshh encloses the translated results of $$""..."" + quoting in single quotes instead of double quotes. If the string is not translated, this has no effect. nnuullllgglloobb If set, pathname expansion patterns which match no files @@ -6857,73 +6880,73 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS removed, rather than expanding to themselves. ppaattssuubb__rreeppllaacceemmeenntt If set, bbaasshh expands occurrences of && in the replacement - string of pattern substitution to the text matched by - the pattern, as described under PPaarraammeetteerr EExxppaannssiioonn + string of pattern substitution to the text matched by + the pattern, as described under PPaarraammeetteerr EExxppaannssiioonn above. This option is enabled by default. pprrooggccoommpp - If set, enable the programmable completion facilities + If set, enable the programmable completion facilities (see PPrrooggrraammmmaabbllee CCoommpplleettiioonn above). This option is en- abled by default. pprrooggccoommpp__aalliiaass - If set, and programmable completion is enabled, bbaasshh - treats a command name that doesn't have any completions + If set, and programmable completion is enabled, bbaasshh + treats a command name that doesn't have any completions as a possible alias and attempts alias expansion. If it - has an alias, bbaasshh attempts programmable completion us- + has an alias, bbaasshh attempts programmable completion us- ing the command word resulting from the expanded alias. pprroommppttvvaarrss If set, prompt strings undergo parameter expansion, com- - mand substitution, arithmetic expansion, and quote re- - moval after being expanded as described in PPRROOMMPPTTIINNGG + mand substitution, arithmetic expansion, and quote re- + moval after being expanded as described in PPRROOMMPPTTIINNGG above. This option is enabled by default. rreessttrriicctteedd__sshheellll - The shell sets this option if it is started in re- - stricted mode (see RREESSTTRRIICCTTEEDD SSHHEELLLL below). The value - may not be changed. This is not reset when the startup - files are executed, allowing the startup files to dis- + The shell sets this option if it is started in re- + stricted mode (see RREESSTTRRIICCTTEEDD SSHHEELLLL below). The value + may not be changed. This is not reset when the startup + files are executed, allowing the startup files to dis- cover whether or not a shell is restricted. sshhiifftt__vveerrbboossee - If set, the sshhiifftt builtin prints an error message when + If set, the sshhiifftt builtin prints an error message when the shift count exceeds the number of positional parame- ters. ssoouurrcceeppaatthh If set, the .. (ssoouurrccee) builtin uses the value of PPAATTHH to - find the directory containing the file supplied as an - argument when the --pp option is not supplied. This op- + find the directory containing the file supplied as an + argument when the --pp option is not supplied. This op- tion is enabled by default. vvaarrrreeddiirr__cclloossee - If set, the shell automatically closes file descriptors - assigned using the _{_v_a_r_n_a_m_e_} redirection syntax (see + If set, the shell automatically closes file descriptors + assigned using the _{_v_a_r_n_a_m_e_} redirection syntax (see RREEDDIIRREECCTTIIOONN above) instead of leaving them open when the command completes. xxppgg__eecchhoo - If set, the eecchhoo builtin expands backslash-escape se- - quences by default. If the ppoossiixx shell option is also + If set, the eecchhoo builtin expands backslash-escape se- + quences by default. If the ppoossiixx shell option is also enabled, eecchhoo does not interpret any options. ssuussppeenndd [--ff] - Suspend the execution of this shell until it receives a SSIIGGCCOONNTT - signal. A login shell, or a shell without job control enabled, - cannot be suspended; the --ff option will override this and force - the suspension. The return status is 0 unless the shell is a - login shell or job control is not enabled and --ff is not sup- + Suspend the execution of this shell until it receives a SSIIGGCCOONNTT + signal. A login shell, or a shell without job control enabled, + cannot be suspended; the --ff option will override this and force + the suspension. The return status is 0 unless the shell is a + login shell or job control is not enabled and --ff is not sup- plied. tteesstt _e_x_p_r [[ _e_x_p_r ]] Return a status of 0 (true) or 1 (false) depending on the evalu- - ation of the conditional expression _e_x_p_r. Each operator and - operand must be a separate argument. Expressions are composed - of the primaries described above under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS. - tteesstt does not accept any options, nor does it accept and ignore + ation of the conditional expression _e_x_p_r. Each operator and + operand must be a separate argument. Expressions are composed + of the primaries described above under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS. + tteesstt does not accept any options, nor does it accept and ignore an argument of ---- as signifying the end of options. - Expressions may be combined using the following operators, - listed in decreasing order of precedence. The evaluation de- + Expressions may be combined using the following operators, + listed in decreasing order of precedence. The evaluation de- pends on the number of arguments; see below. tteesstt uses operator precedence when there are five or more arguments. !! _e_x_p_r True if _e_x_p_r is false. (( _e_x_p_r )) - Returns the value of _e_x_p_r. This may be used to override + Returns the value of _e_x_p_r. This may be used to override normal operator precedence. _e_x_p_r_1 -aa _e_x_p_r_2 True if both _e_x_p_r_1 and _e_x_p_r_2 are true. @@ -6940,111 +6963,111 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS null. 2 arguments If the first argument is !!, the expression is true if and - only if the second argument is null. If the first argu- - ment is one of the unary conditional operators listed - above under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS, the expression is + only if the second argument is null. If the first argu- + ment is one of the unary conditional operators listed + above under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS, 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. 3 arguments The following conditions are applied in the order listed. - If the second argument is one of the binary conditional + If the second argument is one of the binary conditional operators listed above under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS, the result of the expression is the result of the binary test - using the first and third arguments as operands. The --aa - and --oo operators are considered binary operators when - there are three arguments. If the first argument is !!, - the value is the negation of the two-argument test using + using the first and third arguments as operands. The --aa + and --oo operators are considered binary operators when + there are three arguments. If the first argument is !!, + the value is the negation of the two-argument test using the second and third arguments. If the first argument is exactly (( and the third argument is exactly )), the result - is the one-argument test of the second argument. Other- + is the one-argument test of the second argument. Other- wise, the expression is false. 4 arguments The following conditions are applied in the order listed. If the first argument is !!, the result is the negation of - the three-argument expression composed of the remaining - arguments. If the first argument is exactly (( and the + the three-argument expression composed of the remaining + arguments. If the first argument is exactly (( and the fourth argument is exactly )), the result is the two-argu- - ment test of the second and third arguments. Otherwise, - the expression is parsed and evaluated according to + ment test of the second and third arguments. Otherwise, + the expression is parsed and evaluated according to precedence using the rules listed above. 5 or more arguments - The expression is parsed and evaluated according to + The expression is parsed and evaluated according to precedence using the rules listed above. When the shell is in posix mode, or if the expression is part of the [[[[ command, the << and >> operators sort using the current lo- - cale. If the shell is not in posix mode, the tteesstt and [[ com- + cale. If the shell is not in posix mode, the tteesstt and [[ com- mands sort lexicographically using ASCII ordering. - The historical operator-precedence parsing with 4 or more argu- - ments can lead to ambiguities when it encounters strings that - look like primaries. The POSIX standard has deprecated the --aa - and --oo primaries and enclosing expressions within parentheses. - Scripts should no longer use them. It's much more reliable to - restrict test invocations to a single primary, and to replace + The historical operator-precedence parsing with 4 or more argu- + ments can lead to ambiguities when it encounters strings that + look like primaries. The POSIX standard has deprecated the --aa + and --oo primaries and enclosing expressions within parentheses. + Scripts should no longer use them. It's much more reliable to + restrict test invocations to a single primary, and to replace uses of --aa and --oo with the shell's &&&& and |||| list operators. - ttiimmeess Print the accumulated user and system times for the shell and + ttiimmeess Print the accumulated user and system times for the shell and for processes run from the shell. The return status is 0. ttrraapp [--llppPP] [[_a_c_t_i_o_n] _s_i_g_s_p_e_c ...] The _a_c_t_i_o_n is a command that is read and executed when the shell - receives any of the signals _s_i_g_s_p_e_c. If _a_c_t_i_o_n is absent (and + receives any of the signals _s_i_g_s_p_e_c. If _a_c_t_i_o_n is absent (and there is a single _s_i_g_s_p_e_c) or --, each specified _s_i_g_s_p_e_c is reset - to the value it had when the shell was started. If _a_c_t_i_o_n is - the null string the signal specified by each _s_i_g_s_p_e_c is ignored + to the value it had when the shell was started. If _a_c_t_i_o_n is + the null string the signal specified by each _s_i_g_s_p_e_c is ignored by the shell and by the commands it invokes. - If no arguments are supplied, ttrraapp displays the actions associ- + If no arguments are supplied, ttrraapp displays the actions associ- ated with each trapped signal as a set of ttrraapp commands that can - be reused as shell input to restore the current signal disposi- - tions. If --pp is given, and _a_c_t_i_o_n is not present, then ttrraapp - displays the actions associated with each _s_i_g_s_p_e_c or, if none + be reused as shell input to restore the current signal disposi- + tions. If --pp is given, and _a_c_t_i_o_n is not present, then ttrraapp + displays the actions associated with each _s_i_g_s_p_e_c or, if none are supplied, for all trapped signals, as a set of ttrraapp commands - that can be reused as shell input to restore the current signal - dispositions. The --PP option behaves similarly, but displays - only the actions associated with each _s_i_g_s_p_e_c argument. --PP re- - quires at least one _s_i_g_s_p_e_c argument. The --PP or --pp options may - be used in a subshell environment (e.g., command substitution) - and, as long as they are used before ttrraapp is used to change a + that can be reused as shell input to restore the current signal + dispositions. The --PP option behaves similarly, but displays + only the actions associated with each _s_i_g_s_p_e_c argument. --PP re- + quires at least one _s_i_g_s_p_e_c argument. The --PP or --pp options may + be used in a subshell environment (e.g., command substitution) + and, as long as they are used before ttrraapp is used to change a signal's handling, will display the state of its parent's traps. - The --ll option prints a list of signal names and their corre- - sponding numbers. Each _s_i_g_s_p_e_c is either a signal name defined + The --ll option prints a list of signal names and their corre- + sponding numbers. Each _s_i_g_s_p_e_c is either a signal name defined in <_s_i_g_n_a_l_._h>, or a signal number. Signal names are case insen- - sitive and the SSIIGG prefix is optional. If --ll is supplied with + sitive and the SSIIGG prefix is optional. If --ll is supplied with no _s_i_g_s_p_e_c arguments, it prints a list of valid signal names. - If a _s_i_g_s_p_e_c is EEXXIITT (0), _a_c_t_i_o_n is executed on exit from the - shell. If a _s_i_g_s_p_e_c is DDEEBBUUGG, _a_c_t_i_o_n is executed before every - _s_i_m_p_l_e _c_o_m_m_a_n_d, _f_o_r command, _c_a_s_e command, _s_e_l_e_c_t command, (( - arithmetic command, [[ conditional command, arithmetic _f_o_r com- - mand, and before the first command executes in a shell function - (see SSHHEELLLL GGRRAAMMMMAARR above). Refer to the description of the - eexxttddeebbuugg shell option (see sshhoopptt above) for details of its ef- - fect on the DDEEBBUUGG trap. If a _s_i_g_s_p_e_c is RREETTUURRNN, _a_c_t_i_o_n is exe- + If a _s_i_g_s_p_e_c is EEXXIITT (0), _a_c_t_i_o_n is executed on exit from the + shell. If a _s_i_g_s_p_e_c is DDEEBBUUGG, _a_c_t_i_o_n is executed before every + _s_i_m_p_l_e _c_o_m_m_a_n_d, _f_o_r command, _c_a_s_e command, _s_e_l_e_c_t command, (( + arithmetic command, [[ conditional command, arithmetic _f_o_r com- + mand, and before the first command executes in a shell function + (see SSHHEELLLL GGRRAAMMMMAARR above). Refer to the description of the + eexxttddeebbuugg shell option (see sshhoopptt above) for details of its ef- + fect on the DDEEBBUUGG trap. If a _s_i_g_s_p_e_c is RREETTUURRNN, _a_c_t_i_o_n is exe- cuted each time a shell function or a script executed with the .. or ssoouurrccee builtins finishes executing. - If a _s_i_g_s_p_e_c is EERRRR, _a_c_t_i_o_n is executed whenever a pipeline - (which may consist of a single simple command), a list, or a - compound command returns a non-zero exit status, subject to the - following conditions. The EERRRR trap is not executed if the + If a _s_i_g_s_p_e_c is EERRRR, _a_c_t_i_o_n is executed whenever a pipeline + (which may consist of a single simple command), a list, or a + compound command returns a non-zero exit status, subject to the + following conditions. The EERRRR trap is not executed if the failed command is part of the command list immediately following a wwhhiillee or uunnttiill reserved word, part of the test in an _i_f state- - ment, part of a command executed in a &&&& or |||| list except the - command following the final &&&& or ||||, any command in a pipeline - but the last (subject to the state of the ppiippeeffaaiill shell op- - tion), or if the command's return value is being inverted using + ment, part of a command executed in a &&&& or |||| list except the + command following the final &&&& or ||||, any command in a pipeline + but the last (subject to the state of the ppiippeeffaaiill shell op- + tion), or if the command's return value is being inverted using !!. These are the same conditions obeyed by the eerrrreexxiitt (--ee) op- tion. When the shell is not interactive, signals ignored upon entry to the shell cannot be trapped or reset. Interactive shells permit trapping signals ignored on entry. 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 + 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 _s_i_g_s_p_e_c is invalid; otherwise ttrraapp returns true. ttrruuee Does nothing, returns a 0 status. @@ -7053,61 +7076,61 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS Indicate how each _n_a_m_e would be interpreted if used as a command name. - If the --tt option is used, ttyyppee prints a string which is one of - _a_l_i_a_s, _k_e_y_w_o_r_d, _f_u_n_c_t_i_o_n, _b_u_i_l_t_i_n, or _f_i_l_e if _n_a_m_e is an alias, - shell reserved word, function, builtin, or executable file, re- - spectively. If the _n_a_m_e is not found, ttyyppee prints nothing and + If the --tt option is used, ttyyppee prints a string which is one of + _a_l_i_a_s, _k_e_y_w_o_r_d, _f_u_n_c_t_i_o_n, _b_u_i_l_t_i_n, or _f_i_l_e if _n_a_m_e is an alias, + shell reserved word, function, builtin, or executable file, re- + spectively. If the _n_a_m_e is not found, ttyyppee prints nothing and returns a non-zero exit status. - If the --pp option is used, ttyyppee either returns the pathname of - the executable file that would be found by searching $$PPAATTHH for + If the --pp option is used, ttyyppee either returns the pathname of + the executable file that would be found by searching $$PPAATTHH for _n_a_m_e or nothing if "type -t name" would not return _f_i_l_e. The --PP - option forces a PPAATTHH search for each _n_a_m_e, even if "type -t + option forces a PPAATTHH search for each _n_a_m_e, even if "type -t name" would not return _f_i_l_e. If _n_a_m_e is present in the table of - hashed commands, --pp and --PP print the hashed value, which is not + hashed commands, --pp and --PP print the hashed value, which is not necessarily the file that appears first in PPAATTHH. - If the --aa option is used, ttyyppee prints all of the places that - contain a command named _n_a_m_e. This includes aliases, reserved - words, functions, and builtins, but the path search options (--pp - and --PP) can be supplied to restrict the output to executable - files. ttyyppee does not consult the table of hashed commands when + If the --aa option is used, ttyyppee prints all of the places that + contain a command named _n_a_m_e. This includes aliases, reserved + words, functions, and builtins, but the path search options (--pp + and --PP) can be supplied to restrict the output to executable + files. ttyyppee does not consult the table of hashed commands when using --aa with --pp, and only performs a PPAATTHH search for _n_a_m_e. The --ff option suppresses shell function lookup, as with the ccoomm-- - mmaanndd builtin. ttyyppee returns true if all of the arguments are + mmaanndd builtin. ttyyppee returns true if all of the arguments are found, false if any are not found. uulliimmiitt [--HHSS] --aa uulliimmiitt [--HHSS] [--bbccddeeffiikkllmmnnppqqrrssttuuvvxxPPRRTT [_l_i_m_i_t]] - Provides control over the resources available to the shell and + Provides control over the resources available to the shell and to processes it starts, on systems that allow such control. - The --HH and --SS options specify whether the hard or soft limit is + The --HH and --SS options specify whether 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 --HH nor --SS is speci- + to the value of the hard limit. If neither --HH nor --SS is speci- fied, uulliimmiitt sets both the soft and hard limits. The value of _l_i_m_i_t can be a number in the unit specified for the - resource or one of the special values hhaarrdd, ssoofftt, or uunnlliimmiitteedd, - which stand for the current hard limit, the current soft limit, - and no limit, respectively. If _l_i_m_i_t is omitted, uulliimmiitt prints - the current value of the soft limit of the resource, unless the - --HH option is given. When more than one resource is specified, - the limit name and unit, if appropriate, are printed before the + resource or one of the special values hhaarrdd, ssoofftt, or uunnlliimmiitteedd, + which stand for the current hard limit, the current soft limit, + and no limit, respectively. If _l_i_m_i_t is omitted, uulliimmiitt prints + the current value of the soft limit of the resource, unless the + --HH option is given. When more than one resource is specified, + the limit name and unit, if appropriate, are printed before the value. Other options are interpreted as follows: --aa Report all current limits; no limits are set. --bb The maximum socket buffer size. --cc The maximum size of core files created. --dd The maximum size of a process's data segment. --ee The maximum scheduling priority ("nice"). - --ff The maximum size of files written by the shell and its + --ff The maximum size of files written by the shell and its children. --ii The maximum number of pending signals. --kk The maximum number of kqueues that may be allocated. --ll The maximum size that may be locked into memory. - --mm The maximum resident set size (many systems do not honor + --mm The maximum resident set size (many systems do not honor this limit). --nn The maximum number of open file descriptors (most systems do not allow this value to be set). @@ -7116,146 +7139,146 @@ SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS --rr The maximum real-time scheduling priority. --ss The maximum stack size. --tt The maximum amount of cpu time in seconds. - --uu The maximum number of processes available to a single + --uu The maximum number of processes available to a single user. - --vv The maximum amount of virtual memory available to the + --vv The maximum amount of virtual memory available to the shell and, on some systems, to its children. --xx The maximum number of file locks. --PP The maximum number of pseudoterminals. - --RR The maximum time a real-time process can run before + --RR The maximum time a real-time process can run before blocking, in microseconds. --TT The maximum number of threads. - If _l_i_m_i_t is supplied, and the --aa option is not used, _l_i_m_i_t is - the new value of the specified resource. If no option is sup- + If _l_i_m_i_t is supplied, and the --aa option is not used, _l_i_m_i_t is + the new value of the specified resource. If no option is sup- plied, then --ff is assumed. - Values are in 1024-byte increments, except for --tt, which is in - seconds; --RR, which is in microseconds; --pp, which is in units of - 512-byte blocks; --PP, --TT, --bb, --kk, --nn, and --uu, which are unscaled - values; and, when in posix mode, --cc and --ff, which are in - 512-byte increments. The return status is 0 unless an invalid + Values are in 1024-byte increments, except for --tt, which is in + seconds; --RR, which is in microseconds; --pp, which is in units of + 512-byte blocks; --PP, --TT, --bb, --kk, --nn, and --uu, which are unscaled + values; and, when in posix mode, --cc and --ff, which are in + 512-byte increments. The return status is 0 unless an invalid option or argument is supplied, or an error occurs while setting a new limit. uummaasskk [--pp] [--SS] [_m_o_d_e] - Set the user file-creation mask to _m_o_d_e. If _m_o_d_e begins with a + Set the user file-creation mask to _m_o_d_e. If _m_o_d_e begins with a digit, it is interpreted as an octal number; otherwise it is in- - terpreted as a symbolic mode mask similar to that accepted by + terpreted as a symbolic mode mask similar to that accepted by _c_h_m_o_d(1). If _m_o_d_e is omitted, uummaasskk prints the current value of the mask. The --SS option without a _m_o_d_e argument prints the mask in a symbolic format; the default output is an octal number. If the --pp option is supplied, and _m_o_d_e is omitted, the output is in - a form that may be reused as input. The return status is zero - if the mode was successfully changed or if no _m_o_d_e argument was + a form that may be reused as input. The return status is zero + if the mode was successfully changed or if no _m_o_d_e argument was supplied, and non-zero otherwise. uunnaalliiaass [-aa] [_n_a_m_e ...] - Remove each _n_a_m_e from the list of defined aliases. If --aa is - supplied, remove all alias definitions. The return value is + Remove each _n_a_m_e from the list of defined aliases. If --aa is + supplied, remove all alias definitions. The return value is true unless a supplied _n_a_m_e is not a defined alias. uunnsseett [-ffvv] [-nn] [_n_a_m_e ...] - For each _n_a_m_e, remove the corresponding variable or function. + For each _n_a_m_e, remove the corresponding variable or function. If the --vv option is given, each _n_a_m_e refers to a shell variable, - and that variable is removed. If --ff is specified, each _n_a_m_e - refers to a shell function, and the function definition is re- - moved. If the --nn option is supplied, and _n_a_m_e is a variable - with the _n_a_m_e_r_e_f attribute, _n_a_m_e will be unset rather than the - variable it references. --nn has no effect if the --ff option is - supplied. Read-only variables and functions may not be unset. - When variables or functions are removed, they are also removed - from the environment passed to subsequent commands. If no op- - tions are supplied, each _n_a_m_e refers to a variable; if there is - no variable by that name, a function with that name, if any, is - unset. Some shell variables may not be unset. If any of + and that variable is removed. If --ff is specified, each _n_a_m_e + refers to a shell function, and the function definition is re- + moved. If the --nn option is supplied, and _n_a_m_e is a variable + with the _n_a_m_e_r_e_f attribute, _n_a_m_e will be unset rather than the + variable it references. --nn has no effect if the --ff option is + supplied. Read-only variables and functions may not be unset. + When variables or functions are removed, they are also removed + from the environment passed to subsequent commands. If no op- + tions are supplied, each _n_a_m_e refers to a variable; if there is + no variable by that name, a function with that name, if any, is + unset. Some shell variables may not be unset. If any of BBAASSHH__AALLIIAASSEESS, BBAASSHH__AARRGGVV00, BBAASSHH__CCMMDDSS, BBAASSHH__CCOOMMMMAANNDD, BBAASSHH__SSUUBB-- - SSHHEELLLL, BBAASSHHPPIIDD, CCOOMMPP__WWOORRDDBBRREEAAKKSS, DDIIRRSSTTAACCKK, EEPPOOCCHHRREEAALLTTIIMMEE, - EEPPOOCCHHSSEECCOONNDDSS, FFUUNNCCNNAAMMEE, GGRROOUUPPSS, HHIISSTTCCMMDD, LLIINNEENNOO, RRAANNDDOOMM, SSEECC-- - OONNDDSS, or SSRRAANNDDOOMM are unset, they lose their special properties, - even if they are subsequently reset. The exit status is true + SSHHEELLLL, BBAASSHHPPIIDD, CCOOMMPP__WWOORRDDBBRREEAAKKSS, DDIIRRSSTTAACCKK, EEPPOOCCHHRREEAALLTTIIMMEE, + EEPPOOCCHHSSEECCOONNDDSS, FFUUNNCCNNAAMMEE, GGRROOUUPPSS, HHIISSTTCCMMDD, LLIINNEENNOO, RRAANNDDOOMM, SSEECC-- + OONNDDSS, or SSRRAANNDDOOMM are unset, they lose their special properties, + even if they are subsequently reset. The exit status is true unless a _n_a_m_e is readonly or may not be unset. wwaaiitt [--ffnn] [--pp _v_a_r_n_a_m_e] [_i_d ...] Wait for each specified child process _i_d and return the termina- - tion status of the last _i_d. Each _i_d may be a process ID _p_i_d or - a job specification _j_o_b_s_p_e_c; if a jobspec is supplied, wwaaiitt + tion status of the last _i_d. Each _i_d may be a process ID _p_i_d or + a job specification _j_o_b_s_p_e_c; if a jobspec is supplied, wwaaiitt waits for all processes in the job. - If no options or _i_ds are supplied, wwaaiitt waits for all running - background jobs and the last-executed process substitution, if + If no options or _i_ds are supplied, wwaaiitt waits for all running + background jobs and the last-executed process substitution, if its process id is the same as $$!!, and the return status is zero. - If the --nn option is supplied, wwaaiitt waits for any one of the + If the --nn option is supplied, wwaaiitt waits for any one of the given _i_ds or, if no _i_ds are supplied, any job or process substi- tution, to complete and returns its exit status. If none of the - supplied _i_ds is a child of the shell, or if no _i_ds are supplied - and the shell has no unwaited-for children, the exit status is + supplied _i_ds is a child of the shell, or if no _i_ds are supplied + and the shell has no unwaited-for children, the exit status is 127. - If the --pp option is supplied, wwaaiitt assigns the process or job - identifier of the job for which the exit status is returned to - the variable _v_a_r_n_a_m_e named by the option argument. The vari- - able, which cannot be readonly, will be unset initially, before - any assignment. This is useful only when used with the --nn op- + If the --pp option is supplied, wwaaiitt assigns the process or job + identifier of the job for which the exit status is returned to + the variable _v_a_r_n_a_m_e named by the option argument. The vari- + able, which cannot be readonly, will be unset initially, before + any assignment. This is useful only when used with the --nn op- tion. - Supplying the --ff option, when job control is enabled, forces - wwaaiitt to wait for each _i_d to terminate before returning its sta- + Supplying the --ff option, when job control is enabled, forces + wwaaiitt to wait for each _i_d to terminate before returning its sta- tus, instead of returning when it changes status. - If none of the _i_ds specify one of the shell's active child - processes, the return status is 127. If wwaaiitt is interrupted by - a signal, any _v_a_r_n_a_m_e will remain unset, and the return status - will be greater than 128, as described under SSIIGGNNAALLSS above. + If none of the _i_ds specify one of the shell's active child + processes, the return status is 127. If wwaaiitt is interrupted by + a signal, any _v_a_r_n_a_m_e will remain unset, and the return status + will be greater than 128, as described under SSIIGGNNAALLSS above. Otherwise, the return status is the exit status of the last _i_d. SSHHEELLLL CCOOMMPPAATTIIBBIILLIITTYY MMOODDEE - Bash-4.0 introduced the concept of a _s_h_e_l_l _c_o_m_p_a_t_i_b_i_l_i_t_y _l_e_v_e_l, speci- + Bash-4.0 introduced the concept of a _s_h_e_l_l _c_o_m_p_a_t_i_b_i_l_i_t_y _l_e_v_e_l, speci- fied as a set of options to the shopt builtin (ccoommppaatt3311, ccoommppaatt3322, ccoomm-- - ppaatt4400, ccoommppaatt4411, and so on). There is only one current compatibility + ppaatt4400, ccoommppaatt4411, and so on). There is only one current compatibility level -- each option is mutually exclusive. The compatibility level is - intended to allow users to select behavior from previous versions that - is incompatible with newer versions while they migrate scripts to use - current features and behavior. It's intended to be a temporary solu- + intended to allow users to select behavior from previous versions that + is incompatible with newer versions while they migrate scripts to use + current features and behavior. It's intended to be a temporary solu- tion. - This section does not mention behavior that is standard for a particu- - lar version (e.g., setting ccoommppaatt3322 means that quoting the right hand - side of the regexp matching operator quotes special regexp characters - in the word, which is default behavior in bash-3.2 and subsequent ver- + This section does not mention behavior that is standard for a particu- + lar version (e.g., setting ccoommppaatt3322 means that quoting the right hand + side of the regexp matching operator quotes special regexp characters + in the word, which is default behavior in bash-3.2 and subsequent ver- sions). - If a user enables, say, ccoommppaatt3322, it may affect the behavior of other - compatibility levels up to and including the current compatibility - level. The idea is that each compatibility level controls behavior - that changed in that version of bbaasshh, but that behavior may have been - present in earlier versions. For instance, the change to use locale- - based comparisons with the [[[[ command came in bash-4.1, and earlier + If a user enables, say, ccoommppaatt3322, it may affect the behavior of other + compatibility levels up to and including the current compatibility + level. The idea is that each compatibility level controls behavior + that changed in that version of bbaasshh, but that behavior may have been + present in earlier versions. For instance, the change to use locale- + based comparisons with the [[[[ command came in bash-4.1, and earlier versions used ASCII-based comparisons, so enabling ccoommppaatt3322 will enable - ASCII-based comparisons as well. That granularity may not be suffi- - cient for all uses, and as a result users should employ compatibility - levels carefully. Read the documentation for a particular feature to + ASCII-based comparisons as well. That granularity may not be suffi- + cient for all uses, and as a result users should employ compatibility + levels carefully. Read the documentation for a particular feature to find out the current behavior. - Bash-4.3 introduced a new shell variable: BBAASSHH__CCOOMMPPAATT. The value as- + Bash-4.3 introduced a new shell variable: BBAASSHH__CCOOMMPPAATT. The value as- signed to this variable (a decimal version number like 4.2, or an inte- - ger corresponding to the ccoommppaatt_N_N option, like 42) determines the com- + ger corresponding to the ccoommppaatt_N_N option, like 42) determines the com- patibility level. Starting with bash-4.4, bbaasshh began deprecating older compatibility lev- els. Eventually, the options will be removed in favor of BBAASSHH__CCOOMMPPAATT. - Bash-5.0 was the final version for which there was an individual shopt - option for the previous version. BBAASSHH__CCOOMMPPAATT is the only mechanism to + Bash-5.0 was the final version for which there was an individual shopt + option for the previous version. BBAASSHH__CCOOMMPPAATT is the only mechanism to control the compatibility level in versions newer than bash-5.0. - The following table describes the behavior changes controlled by each + The following table describes the behavior changes controlled by each compatibility level setting. The ccoommppaatt_N_N tag is used as shorthand for setting the compatibility level to _N_N using one of the following mecha- - nisms. For versions prior to bash-5.0, the compatibility level may be - set using the corresponding ccoommppaatt_N_N shopt option. For bash-4.3 and - later versions, the BBAASSHH__CCOOMMPPAATT variable is preferred, and it is re- + nisms. For versions prior to bash-5.0, the compatibility level may be + set using the corresponding ccoommppaatt_N_N shopt option. For bash-4.3 and + later versions, the BBAASSHH__CCOOMMPPAATT variable is preferred, and it is re- quired for bash-5.1 and later versions. ccoommppaatt3311 @@ -7263,173 +7286,173 @@ SSHHEELLLL CCOOMMPPAATTIIBBIILLIITTYY MMOODDEE ator (=~) has no special effect. ccoommppaatt3322 - +o The << and >> operators to the [[[[ command do not consider + +o The << and >> operators to the [[[[ command do not consider the current locale when comparing strings; they use ASCII ordering. ccoommppaatt4400 - +o The << and >> operators to the [[[[ command do not consider + +o The << and >> operators to the [[[[ command do not consider the current locale when comparing strings; they use ASCII ordering. BBaasshh versions prior to bash-4.1 use ASCII col- - lation and _s_t_r_c_m_p(3); bash-4.1 and later use the current + lation and _s_t_r_c_m_p(3); bash-4.1 and later use the current locale's collation sequence and _s_t_r_c_o_l_l(3). ccoommppaatt4411 - +o In posix mode, ttiimmee may be followed by options and still + +o In posix mode, ttiimmee may be followed by options and still be recognized as a reserved word (this is POSIX interpre- tation 267). +o In _p_o_s_i_x mode, the parser requires that an even number of - single quotes occur in the _w_o_r_d portion of a double- - quoted parameter expansion and treats them specially, so - that characters within the single quotes are considered + single quotes occur in the _w_o_r_d portion of a double- + quoted parameter expansion and treats them specially, so + that characters within the single quotes are considered quoted (this is POSIX interpretation 221). ccoommppaatt4422 +o The replacement string in double-quoted pattern substitu- - tion does not undergo quote removal, as it does in ver- + tion does not undergo quote removal, as it does in ver- sions after bash-4.2. - +o In posix mode, single quotes are considered special when - expanding the _w_o_r_d portion of a double-quoted parameter - expansion and can be used to quote a closing brace or - other special character (this is part of POSIX interpre- - tation 221); in later versions, single quotes are not + +o In posix mode, single quotes are considered special when + expanding the _w_o_r_d portion of a double-quoted parameter + expansion and can be used to quote a closing brace or + other special character (this is part of POSIX interpre- + tation 221); in later versions, single quotes are not special within double-quoted word expansions. ccoommppaatt4433 - +o Word expansion errors are considered non-fatal errors - that cause the current command to fail, even in posix - mode (the default behavior is to make them fatal errors + +o Word expansion errors are considered non-fatal errors + that cause the current command to fail, even in posix + mode (the default behavior is to make them fatal errors that cause the shell to exit). - +o When executing a shell function, the loop state + +o When executing a shell function, the loop state (while/until/etc.) is not reset, so bbrreeaakk or ccoonnttiinnuuee in that function will break or continue loops in the calling context. Bash-4.4 and later reset the loop state to pre- vent this. ccoommppaatt4444 - +o The shell sets up the values used by BBAASSHH__AARRGGVV and - BBAASSHH__AARRGGCC so they can expand to the shell's positional - parameters even if extended debugging mode is not en- + +o The shell sets up the values used by BBAASSHH__AARRGGVV and + BBAASSHH__AARRGGCC so they can expand to the shell's positional + parameters even if extended debugging mode is not en- abled. - +o A subshell inherits loops from its parent context, so - bbrreeaakk or ccoonnttiinnuuee will cause the subshell to exit. - Bash-5.0 and later reset the loop state to prevent the + +o A subshell inherits loops from its parent context, so + bbrreeaakk or ccoonnttiinnuuee will cause the subshell to exit. + Bash-5.0 and later reset the loop state to prevent the exit - +o Variable assignments preceding builtins like eexxppoorrtt and + +o Variable assignments preceding builtins like eexxppoorrtt and rreeaaddoonnllyy that set attributes continue to affect variables with the same name in the calling environment even if the shell is not in posix mode. ccoommppaatt5500 - +o Bash-5.1 changed the way $$RRAANNDDOOMM is generated to intro- - duce slightly more randomness. If the shell compatibil- + +o Bash-5.1 changed the way $$RRAANNDDOOMM is generated to intro- + duce slightly more randomness. If the shell compatibil- ity level is set to 50 or lower, it reverts to the method - from bash-5.0 and previous versions, so seeding the ran- - dom number generator by assigning a value to RRAANNDDOOMM will + from bash-5.0 and previous versions, so seeding the ran- + dom number generator by assigning a value to RRAANNDDOOMM will produce the same sequence as in bash-5.0. - +o If the command hash table is empty, bash versions prior - to bash-5.1 printed an informational message to that ef- - fect, even when producing output that can be reused as - input. Bash-5.1 suppresses that message when the --ll op- + +o If the command hash table is empty, bash versions prior + to bash-5.1 printed an informational message to that ef- + fect, even when producing output that can be reused as + input. Bash-5.1 suppresses that message when the --ll op- tion is supplied. ccoommppaatt5511 - +o The uunnsseett builtin treats attempts to unset array sub- - scripts @@ and ** differently depending on whether the ar- - ray is indexed or associative, and differently than in + +o The uunnsseett builtin treats attempts to unset array sub- + scripts @@ and ** differently depending on whether the ar- + ray is indexed or associative, and differently than in previous versions. +o Arithmetic commands ( ((((...)))) ) and the expressions in an arithmetic for statement can be expanded more than once. - +o Expressions used as arguments to arithmetic operators in - the [[[[ conditional command can be expanded more than + +o Expressions used as arguments to arithmetic operators in + the [[[[ conditional command can be expanded more than once. - +o The expressions in substring parameter brace expansion + +o The expressions in substring parameter brace expansion can be expanded more than once. +o The expressions in the $$((((...)))) word expansion can be ex- panded more than once. - +o Arithmetic expressions used as indexed array subscripts + +o Arithmetic expressions used as indexed array subscripts can be expanded more than once. - +o tteesstt --vv, when given an argument of AA[[@@]], where AA is an + +o tteesstt --vv, when given an argument of AA[[@@]], where AA is an existing associative array, will return true if the array - has any set elements. Bash-5.2 will look for and report + has any set elements. Bash-5.2 will look for and report on a key named @@. +o The ${_p_a_r_a_m_e_t_e_r[[::]]==_v_a_l_u_e} word expansion will return - _v_a_l_u_e, before any variable-specific transformations have + _v_a_l_u_e, before any variable-specific transformations have been performed (e.g., converting to lowercase). Bash-5.2 will return the final value assigned to the variable. - +o Parsing command substitutions will behave as if extended + +o Parsing command substitutions will behave as if extended globbing (see the description of the sshhoopptt builtin above) - is enabled, so that parsing a command substitution con- + is enabled, so that parsing a command substitution con- taining an extglob pattern (say, as part of a shell func- - tion) will not fail. This assumes the intent is to en- - able extglob before the command is executed and word ex- - pansions are performed. It will fail at word expansion - time if extglob hasn't been enabled by the time the com- + tion) will not fail. This assumes the intent is to en- + able extglob before the command is executed and word ex- + pansions are performed. It will fail at word expansion + time if extglob hasn't been enabled by the time the com- mand is executed. ccoommppaatt5522 - +o The tteesstt builtin uses its historical algorithm to parse - parenthesized subexpressions when given five or more ar- + +o The tteesstt builtin uses its historical algorithm to parse + parenthesized subexpressions when given five or more ar- guments. - +o If the --pp or --PP option is supplied to the bbiinndd builtin, + +o If the --pp or --PP option is supplied to the bbiinndd builtin, bbiinndd treats any arguments remaining after option process- - ing as bindable command names, and displays any key se- - quences bound to those commands, instead of treating the + ing as bindable command names, and displays any key se- + quences bound to those commands, instead of treating the arguments as key sequences to bind. RREESSTTRRIICCTTEEDD SSHHEELLLL If bbaasshh is started with the name rrbbaasshh, or the --rr option is supplied at - invocation, the shell becomes _r_e_s_t_r_i_c_t_e_d. A restricted shell is used - to set up an environment more controlled than the standard shell. It - behaves identically to bbaasshh with the exception that the following are + invocation, the shell becomes _r_e_s_t_r_i_c_t_e_d. A restricted shell is used + to set up an environment more controlled than the standard shell. It + behaves identically to bbaasshh with the exception that the following are disallowed or not performed: +o Changing directories with ccdd. - +o Setting or unsetting the values of SSHHEELLLL, PPAATTHH, HHIISSTTFFIILLEE, EENNVV, + +o Setting or unsetting the values of SSHHEELLLL, PPAATTHH, HHIISSTTFFIILLEE, EENNVV, or BBAASSHH__EENNVV. +o Specifying command names containing //. - +o Specifying a filename containing a // as an argument to the .. + +o Specifying a filename containing a // as an argument to the .. builtin command. - +o Using the --pp option to the .. builtin command to specify a + +o Using the --pp option to the .. builtin command to specify a search path. - +o Specifying a filename containing a slash as an argument to the + +o Specifying a filename containing a slash as an argument to the hhiissttoorryy builtin command. - +o Specifying a filename containing a slash as an argument to the + +o Specifying a filename containing a slash as an argument to the --pp option to the hhaasshh builtin command. - +o Importing function definitions from the shell environment at + +o Importing function definitions from the shell environment at startup. - +o Parsing the values of BBAASSHHOOPPTTSS and SSHHEELLLLOOPPTTSS from the shell en- + +o Parsing the values of BBAASSHHOOPPTTSS and SSHHEELLLLOOPPTTSS from the shell en- vironment at startup. - +o Redirecting output using the >, >|, <>, >&, &>, and >> redirec- + +o Redirecting output using the >, >|, <>, >&, &>, and >> redirec- tion operators. +o Using the eexxeecc builtin command to replace the shell with another command. - +o Adding or deleting builtin commands with the --ff and --dd options + +o Adding or deleting builtin commands with the --ff and --dd options to the eennaabbllee builtin command. - +o Using the eennaabbllee builtin command to enable disabled shell + +o Using the eennaabbllee builtin command to enable disabled shell builtins. +o Specifying the --pp option to the ccoommmmaanndd builtin command. - +o Turning off restricted mode with sseett ++rr or sshhoopptt --uu rree-- + +o Turning off restricted mode with sseett ++rr or sshhoopptt --uu rree-- ssttrriicctteedd__sshheellll. These restrictions are enforced after any startup files are read. When a command that is found to be a shell script is executed (see CCOOMM-- - MMAANNDD EEXXEECCUUTTIIOONN above), rrbbaasshh turns off any restrictions in the shell + MMAANNDD EEXXEECCUUTTIIOONN above), rrbbaasshh turns off any restrictions in the shell spawned to execute the script. SSEEEE AALLSSOO @@ -7454,10 +7477,10 @@ FFIILLEESS _~_/_._b_a_s_h_r_c The individual per-interactive-shell startup file _~_/_._b_a_s_h___l_o_g_o_u_t - The individual login shell cleanup file, executed when a login + The individual login shell cleanup file, executed when a login shell exits _~_/_._b_a_s_h___h_i_s_t_o_r_y - The default value of HHIISSTTFFIILLEE, the file in which bash saves the + The default value of HHIISSTTFFIILLEE, the file in which bash saves the command history _~_/_._i_n_p_u_t_r_c Individual _r_e_a_d_l_i_n_e initialization file @@ -7471,15 +7494,15 @@ AAUUTTHHOORRSS BBUUGG RREEPPOORRTTSS If you find a bug in bbaasshh, 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 bbaasshh. The latest version is always available from + make sure that it really is a bug, and that it appears in the latest + version of bbaasshh. The latest version is always available from _f_t_p_:_/_/_f_t_p_._g_n_u_._o_r_g_/_p_u_b_/_g_n_u_/_b_a_s_h_/ and _h_t_t_p_:_/_/_g_i_t_._s_a_v_a_n_- _n_a_h_._g_n_u_._o_r_g_/_c_g_i_t_/_b_a_s_h_._g_i_t_/_s_n_a_p_s_h_o_t_/_b_a_s_h_-_m_a_s_t_e_r_._t_a_r_._g_z. - Once you have determined that a bug actually exists, use the _b_a_s_h_b_u_g - command to submit a bug report. If you have a fix, you are encouraged + Once you have determined that a bug actually exists, use the _b_a_s_h_b_u_g + command to submit a bug report. If you have a fix, you are encouraged to mail that as well! You may send suggestions and "philosophical" bug - reports to _b_u_g_-_b_a_s_h_@_g_n_u_._o_r_g or post them to the Usenet newsgroup + reports to _b_u_g_-_b_a_s_h_@_g_n_u_._o_r_g or post them to the Usenet newsgroup ggnnuu..bbaasshh..bbuugg. ALL bug reports should include: @@ -7490,7 +7513,7 @@ BBUUGG RREEPPOORRTTSS A description of the bug behavior A short script or "recipe" which exercises the bug - _b_a_s_h_b_u_g inserts the first three items automatically into the template + _b_a_s_h_b_u_g inserts the first three items automatically into the template it provides for filing a bug report. Comments and bug reports concerning this manual page should be directed @@ -7506,14 +7529,14 @@ BBUUGGSS Shell builtin commands and functions are not stoppable/restartable. - Compound commands and command lists of the form "a ; b ; c" are not - handled gracefully when combined with process suspension. When a - process is stopped, the shell immediately executes the next command in - the list or breaks out of any existing loops. It suffices to enclose - the command in parentheses to force it into a subshell, which may be - stopped as a unit, or to start the command in the background and imme- + Compound commands and command lists of the form "a ; b ; c" are not + handled gracefully when combined with process suspension. When a + process is stopped, the shell immediately executes the next command in + the list or breaks out of any existing loops. It suffices to enclose + the command in parentheses to force it into a subshell, which may be + stopped as a unit, or to start the command in the background and imme- diately bring it into the foreground. Array variables may not (yet) be exported. -GNU Bash 5.3 2025 August 25 _B_A_S_H(1) +GNU Bash 5.3 2025 September 6 _B_A_S_H(1) diff --git a/doc/bash.1 b/doc/bash.1 index 4f89ffe20..75bd2ba3d 100644 --- a/doc/bash.1 +++ b/doc/bash.1 @@ -5,7 +5,7 @@ .\" Case Western Reserve University .\" chet.ramey@case.edu .\" -.\" Last Change: Mon Aug 25 11:35:58 EDT 2025 +.\" Last Change: Sat Sep 6 15:27:27 EDT 2025 .\" .\" For bash_builtins, strip all but "SHELL BUILTIN COMMANDS" section .\" For rbash, strip all but "RESTRICTED SHELL" section @@ -21,7 +21,7 @@ .ds zY \" empty .if \n(zZ=1 .ig zZ .if \n(zY=1 .ig zY -.TH BASH 1 "2025 August 25" "GNU Bash 5.3" +.TH BASH 1 "2025 September 6" "GNU Bash 5.3" .\" .ie \n(.g \{\ .ds ' \(aq @@ -552,17 +552,32 @@ It is one of the following symbols: .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 +.IP \(bu the first word of a command (see .SM .B "SHELL GRAMMAR" -below), the third word of a +below); +.IP \(bu +the first word following a reserved word +other than \fBcase\fP, \fBfor\fP, \fBselect\fP, or \fBin\fP; +.IP \(bu +the third word of a .B case -or -.B select command -(only \fBin\fP is valid), or the third word of a +(only \fBin\fP is valid); +.IP \(bu +the third word of a .B for -command (only \fBin\fP and \fBdo\fP are valid): +or +.B select +command (only \fBin\fP and \fBdo\fP are valid); +.IP \(bu +following a control operator. +.PP +The shell will also recognize reserved words where the syntax of a command +specifically requires the reserved word as the only correct token. +.PP +The following are reserved words: .if t .RS .PP .B @@ -667,48 +682,18 @@ If the \fBlastpipe\fP option is enabled using the \fBshopt\fP builtin and job control is not active, the last element of a pipeline may be run by the shell process. .SS Lists -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 +A \fIlist\fP is a sequence of one or more AND or OR lists +separated by one of the operators .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. -These are referred to as \fIasynchronous\fP commands. -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. +.BR , +and optionally terminated by one of those three characters. .PP AND and OR lists are sequences of one or more pipelines separated by the \fB&&\fP and \fB||\fP control operators, respectively. AND and OR lists are executed with left associativity. +.PP An AND list has the form .RS .PP @@ -733,6 +718,35 @@ 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. +.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. +These are referred to as \fIasynchronous\fP commands. +Commands separated or terminated by +.B ; +(or an equivalent +.BR ) +are executed sequentially; the shell waits for each +command to terminate in turn. +.PP +The return status of a list is the exit status of the last command executed. .SS Compound Commands A \fIcompound command\fP is one of the following. In most cases a \fIlist\fP in a command's description may be separated from @@ -904,7 +918,7 @@ the entire conditional expression. .RE .TP \fBfor\fP \fIname\fP [ [ \fBin\fP \fIword .\|.\|.\&\fP ] ; ] \fBdo\fP \fIlist\fP ; \fBdone\fP -First, expand The list of words following \fBin\fP, generating a list +First, expand the list of words following \fBin\fP, generating a list of items. Then, the variable \fIname\fP is set to each element of this list in turn, and \fIlist\fP is executed each time. @@ -938,7 +952,7 @@ Use the \fBbreak\fP and \fPcontinue\fP builtins below) to control loop execution. .TP -\fBselect\fP \fIname\fP [ \fBin\fP \fIword\fP ] ; \fBdo\fP \fIlist\fP ; \fBdone\fP +\fBselect\fP \fIname\fP [ [ \fBin\fP \fIword .\|.\|.\&\fP ] ; ] \fBdo\fP \fIlist\fP ; \fBdone\fP First, expand the list of words following \fBin\fP, generating a list of items, and print the set of expanded words the standard error, each preceded by a number. @@ -985,8 +999,6 @@ using the matching rules described under .B "Pattern Matching" below. -A pattern list is a set of one or more patterns separated by \|, -and the ) operator terminates the pattern list. The \fIword\fP is expanded using tilde expansion, parameter and variable expansion, arithmetic expansion, command substitution, process substitution and quote removal. @@ -997,19 +1009,28 @@ If the .B nocasematch shell option is enabled, the match is performed without regard to the case of alphabetic characters. -A \fIclause\fP is a pattern list and an associated \fIlist\fP. +.IP +A \fIpattern list\fP is a set of one or more patterns separated by +.BR | , +and terminated by the \fB)\fP operator. +A case \fIclause\fP is a pattern list and an associated \fIlist\fP, +terminated by \fB;;\fP, \fB;&\fP, or \fB;;&\fP. +The terminator is optional for the last clause preceding \fBesac\fP. +There may be an arbitrary number of case clauses. +The first pattern that matches determines the +\fIlist\fP that is executed. .IP When a match is found, \fBcase\fP executes the corresponding \fIlist\fP. -If the \fB;;\fP operator terminates the case clause, the \fBcase\fP -command completes after the first match. -Using \fB;&\fP in place of \fB;;\fP causes execution to continue with -the \fIlist\fP associated with the next pattern list. -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 +If the \fB;;\fP operator terminates the case clause, +the \fBcase\fP command completes after the first match. +Using the \fB;&\fP terminator continues execution with +the \fIlist\fP associated with the next clause, if any. +Using the \fB;;&\fP terminator causes the shell to test the pattern list +in the next clause, if any, and execute any associated \fIlist\fP if the match succeeds, continuing the case statement execution as if the pattern list had not matched. -The exit status is zero if no pattern matches. .IP +The exit status is zero if no pattern matches. Otherwise, it is the exit status of the last command executed in the last \fIlist\fP executed. .TP diff --git a/doc/bash.html b/doc/bash.html index 37f2bd997..bcb594c84 100644 --- a/doc/bash.html +++ b/doc/bash.html @@ -1,16971 +1,16414 @@ - -BASH(1) Manual Page - - - - -
BASH(1)2025 August 25BASH(1) -
-
Index -
+ + + + + + + + + +BASH + + + + +

BASH

+ +NAME
+SYNOPSIS
+COPYRIGHT
+DESCRIPTION
+OPTIONS
+ARGUMENTS
+INVOCATION
+DEFINITIONS
+RESERVED WORDS
+SHELL GRAMMAR
+Simple Commands
+Pipelines
+Lists
+Compound Commands
+Coprocesses
+Shell Function Definitions
+COMMENTS
+QUOTING
+Translating Strings
+PARAMETERS
+Positional Parameters
+Special Parameters
+Shell Variables
+Arrays
+EXPANSION
+Brace Expansion
+Tilde Expansion
+Parameter Expansion
+Command Substitution
+Arithmetic Expansion
+Process Substitution
+Word Splitting
+Pathname Expansion
+Quote Removal
+REDIRECTION
+Redirecting Input
+Redirecting Output
+Appending Redirected Output
+Redirecting Standard Output and Standard Error
+Appending Standard Output and Standard Error
+Here Documents
+Here Strings
+Duplicating File Descriptors
+Moving File Descriptors
+Opening File Descriptors for Reading and Writing
+ALIASES
+FUNCTIONS
+ARITHMETIC EVALUATION
+CONDITIONAL EXPRESSIONS
+SIMPLE COMMAND EXPANSION
+COMMAND EXECUTION
+COMMAND EXECUTION ENVIRONMENT
+ENVIRONMENT
+EXIT STATUS
+SIGNALS
+JOB CONTROL
+PROMPTING
+READLINE
+Readline Notation
+Readline Initialization
+Readline Key Bindings
+Readline Variables
+Readline Conditional Constructs
+Searching
+Readline Command Names
+Commands for Moving
+Commands for Manipulating the History
+Commands for Changing Text
+Killing and Yanking
+Numeric Arguments
+Completing
+Keyboard Macros
+Miscellaneous
+Programmable Completion
+HISTORY
+HISTORY EXPANSION
+Event Designators
+Word Designators
+Modifiers
+SHELL BUILTIN COMMANDS
+SHELL COMPATIBILITY MODE
+RESTRICTED SHELL
+SEE ALSO
+FILES
+AUTHORS
+BUG REPORTS
+BUGS
+ +
+ + +

NAME + +

+ + +

bash − GNU +Bourne-Again SHell

+ +

SYNOPSIS + +

+ + +

bash +[options] [command_string | file]

+ +

COPYRIGHT + +

+ + +

Bash is +Copyright (C) 1989-2025 by the Free Software Foundation, +Inc.

+ +

DESCRIPTION + +

+ + +

Bash is a +command language interpreter that executes commands read +from the standard input, from a string, or from a file. It +is a reimplementation and extension of the Bourne shell, the +historical Unix command language interpreter. Bash +also incorporates useful features from the Korn and +C shells (ksh and csh).

+ + +

POSIX +is the name for a family of computing standards based on +Unix. Bash is intended to be a conformant +implementation of the Shell and Utilities portion of the +IEEE POSIX specification (IEEE Standard +1003.1). Bash POSIX mode (hereafter +referred to as posix mode) changes the shell’s +behavior where its default operation differs from the +standard to strictly conform to the standard. See +SEE ALSO below for a reference to a +document that details how posix mode affects +bash’s behavior. Bash can be configured +to be POSIX -conformant by default.

+ +

OPTIONS + +

+ + +

All of the +single-character shell options documented in the description +of the set builtin command, including +−o, can be used as options when the shell is +invoked. In addition, bash interprets the following +options when it is invoked:

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

−c

 +

If the −c option is present, then commands +are read from the first non-option argument +command_string. If there are arguments after the +command_string, the first argument is assigned to +$0 and any remaining arguments are assigned to the +positional parameters. The assignment to $0 sets the +name of the shell, which is used in warning and error +messages.

+

−i

 +

If the −i option is present, the shell is +interactive.

+

−l

 +

Make bash act as if it had been invoked as a +login shell (see INVOCATION +below).

+

−r

 +

If the −r option is present, the shell +becomes restricted (see RESTRICTED +SHELL below).

+

−s

 +

If the −s option is present, or if no +arguments remain after option processing, the shell reads +commands from the standard input. This option allows the +positional parameters to be set when invoking an interactive +shell or when reading input through a pipe.

+

−D

 +

Print a list of all double-quoted strings preceded by +$ on the standard output. These are the strings that +are subject to language translation when the current locale +is not C or POSIX. This implies the +−n option; no commands will be executed.

+

[−+]O +[shopt_option]

-  -

NAME

+

shopt_option is one of +the shell options accepted by the shopt builtin (see +SHELL BUILTIN COMMANDS below). If +shopt_option is present, −O sets the +value of that option; +O unsets it. If +shopt_option is not supplied, bash prints the +names and values of the shell options accepted by +shopt on the standard output. If the invocation +option is +O, the output is displayed in a format +that may be reused as input.

-bash - GNU Bourne-Again SHell -  -

SYNOPSIS

+ + + + + + +
-bash -[options] -[command_string | file] -  -

COPYRIGHT

+

−−

 -Bash is Copyright © 1989-2025 by the Free Software Foundation, Inc. -  -

DESCRIPTION

+

A −− signals the end of options and +disables further option processing. Any arguments after the +−− are treated as a shell script filename +(see below) and arguments passed to that script. An argument +of − is equivalent to +−−.

-Bash +

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.
+−−debugger

-is a command language interpreter that -executes commands read from the standard input, from a string, -or from a file. -It is a reimplementation and extension of the Bourne shell, -the historical Unix command language interpreter. -Bash +

Arrange for the debugger +profile to be executed before the shell starts. Turns on +extended debugging mode (see the description of the +extdebug option to the shopt builtin +below).

-also incorporates useful features from the Korn and C -shells (ksh and csh). -

-POSIX -is the name for a family of computing standards based on Unix. -Bash +

−−dump−po−strings

-is intended to be a conformant implementation of the -Shell and Utilities portion of the IEEE -POSIX -specification (IEEE Standard 1003.1). -Bash +

Equivalent to −D, +but the output is in the GNU gettext “po” +(portable object) file format.

-POSIX -mode (hereafter referred to as posix mode) -changes the shell's behavior where its default operation differs -from the standard to strictly conform to the standard. -See -SEE ALSO - -below for a reference to a document that details how posix mode affects -bash's behavior. -Bash +

−−dump−strings

-can be configured to be -POSIX --conformant by default. -  -

OPTIONS

+

Equivalent to +−D.

-All of the single-character shell options documented in the -description of the set builtin command, including -o, -can be used as options when the shell is invoked. -In addition, bash -interprets the following options when it is invoked: -

+ + + + + + +
-
-
-c -
-If the --c +

−−help

 -option is present, then commands are read from the first non-option argument -command_string. -If there are arguments after the -command_string, +

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

-the first argument is assigned to -$0 -and any remaining arguments are assigned to the positional parameters. -The assignment to -$0 +

−−init−file +file
+−−rcfile file

-sets the name of the shell, which is used in warning and error messages. -
-i +

Execute commands from +file instead of the standard personal initialization +file ~/.bashrc if the shell is interactive (see +INVOCATION below).

-
-If the --i +

−−login

-option is present, the shell is -interactive. +

Equivalent to +−l.

-
-l -
-Make -bash +

−−noediting

-act as if it had been invoked as a login shell (see -INVOCATION +

Do not use the GNU +readline library to read command lines when the shell +is interactive.

- -below). -
-r - -
-If the --r -option is present, the shell becomes -restricted - -(see -RESTRICTED SHELL - - -below). -
-s - -
-If the --s - -option is present, or if no arguments remain after option -processing, the shell reads commands from the standard input. -This option allows the positional parameters to be set -when invoking an interactive shell or when reading input -through a pipe. -
-D - -
-Print a list of all double-quoted strings preceded by $ -on the standard output. -These are the strings that -are subject to language translation when the current locale -is not C or POSIX. -This implies the -n option; no commands will be executed. -
[-+]O [shopt_option] +

−−noprofile

-
-shopt_option is one of the shell options accepted by the -shopt builtin (see -SHELL BUILTIN COMMANDS +

Do not read either the +system-wide startup file /etc/profile or any of the +personal initialization files ~/.bash_profile, +~/.bash_login, or ~/.profile. By default, +bash reads these files when it is invoked as a login +shell (see INVOCATION below).

- -below). -If shopt_option is present, -O sets the value of that option; -+O unsets it. -If shopt_option is not supplied, bash prints -the names and values of the shell -options accepted by shopt on the standard output. -If the invocation option is +O, the output is displayed in a format -that may be reused as input. -
-- + + + + + + +
-
-A --- -signals the end of options and disables further option processing. -Any arguments after the --- +

−−norc

 -are treated as a shell script filename (see below) -and arguments passed to that script. -An argument of -- -is equivalent to --. - -

+

Do not read and execute the personal initialization file +~/.bashrc if the shell is interactive. This option is +on by default if the shell is invoked as sh.

-Bash +

−−posix

-also interprets a number of multi-character options. -These options must appear on the command line before the -single-character options to be recognized. -

+

Enable posix mode; change the +behavior of bash where the default operation differs +from the POSIX standard to match the +standard.

-
-
--debugger -
-Arrange for the debugger profile to be executed before the shell -starts. -Turns on extended debugging mode (see the description of the -extdebug +

−−restricted

-option to the -shopt +

The shell becomes restricted +(see RESTRICTED SHELL below).

-builtin below). -
--dump-po-strings -
-Equivalent to -D, but the output is in the GNU gettext +

−−verbose

-(portable object) file format. -
--dump-strings +

Equivalent to +−v.

-
-Equivalent to -D. -
--help -
-Display a usage message on standard output and exit successfully. -
-
---init-file file -
--rcfile file
+

−−version

-Execute commands from -file +

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

-instead of the standard personal initialization file +

ARGUMENTS + +

-~/.bashrc -if the shell is interactive (see -INVOCATION +

If arguments +remain after option processing, and neither the +−c nor the −s option has been +supplied, the first argument is treated as the name of a +file containing shell commands (a shell script). When +bash is invoked in this fashion, $0 is set to +the name of the file, and the positional parameters are set +to the remaining arguments. Bash reads and executes +commands from this file, then exits. Bash’s +exit status is the exit status of the last command executed +in the script. If no commands are executed, the exit status +is 0. Bash first attempts to open the file in the +current directory, and, if no file is found, searches the +directories in PATH for the +script.

- -below). -
--login +

INVOCATION + +

-
-Equivalent to -l. -
--noediting -
-Do not use the GNU -readline +

A login +shell is one whose first character of argument zero is a +−, or one started with the +−−login option.

-library to read command lines when the shell is interactive. -
--noprofile +

An +interactive shell is one started without non-option +arguments (unless −s is specified) and without +the −c option, and whose standard input and +standard error are both connected to terminals (as +determined by isatty(3)), or one started with the +−i option. Bash sets +PS1 and $− includes +i if the shell is interactive, so a shell script or a +startup file can test this state.

-
-Do not read either the system-wide startup file +

The following +paragraphs describe how bash executes its startup +files. If any of the files exist but cannot be read, +bash reports an error. Tildes are expanded in +filenames as described below under Tilde Expansion in +the EXPANSION section.

+ +

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

+ +

When an +interactive login shell exits, or a non-interactive login +shell executes the exit builtin command, bash +reads and executes commands from the file +~/.bash_logout, if it exists.

+ +

When an +interactive shell that is not a login shell is started, +bash reads and executes commands from +~/.bashrc, if that file exists. The +−−norc option inhibits this behavior. The +−−rcfile file option causes +bash to use file instead of +~/.bashrc.

+ +

When bash +is started non-interactively, to run a shell script, for +example, it looks for the variable +BASH_ENV in the environment, expands +its value if it appears there, and uses the expanded value +as the name of a file to read and execute. Bash +behaves as if the following command were executed:

+ +

if [ −n +"$BASH_ENV" ]; then . "$BASH_ENV"; +fi

+ +

but does not use +the value of the PATH variable to +search for the filename.

+ +

If bash +is invoked with the name sh, it tries to mimic the +startup behavior of historical versions of sh as +closely as possible, while conforming to the +POSIX standard as well. When invoked as an +interactive login shell, or a non-interactive shell with the +−−login option, it first attempts to read +and execute commands from /etc/profile and +~/.profile, in that order. The +−−noprofile option inhibits this +behavior. When invoked as an interactive shell with the name +sh, bash looks for the variable +ENV, expands its value +if it is defined, and uses the expanded value as the name of +a file to read and execute. Since a shell invoked as +sh does not attempt to read and execute commands from +any other startup files, the −−rcfile +option has no effect. A non-interactive shell invoked with +the name sh does not attempt to read any other +startup files.

+ +

When invoked as +sh, bash enters posix mode after reading the +startup files.

+ +

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

+ +

Bash +attempts to determine when it is being run with its standard +input connected to a network connection, as when executed by +the historical and rarely-seen remote shell daemon, usually +rshd, or the secure shell daemon sshd. If +bash determines it is being run non-interactively in +this fashion, it reads and executes commands from +~/.bashrc, if that file exists and is readable. +Bash does not read this file if invoked as sh. +The −−norc option inhibits this behavior, +and the −−rcfile option makes bash +use a different file instead of ~/.bashrc, but +neither rshd nor sshd generally invoke the +shell with those options or allow them to be specified.

+ +

If the shell is +started with the effective user (group) id not equal to the +real user (group) id, and the −p option is not +supplied, no startup files are read, shell functions are not +inherited from the environment, the +SHELLOPTS, BASHOPTS, +CDPATH, and GLOBIGNORE +variables, if they appear in the environment, are ignored, +and the effective user id is set to the real user id. If the +−p option is supplied at invocation, the +startup behavior is the same, but the effective user id is +not reset.

-/etc/profile +

DEFINITIONS + +

-or any of the personal initialization files -~/.bash_profile, +

The following +definitions are used throughout the rest of this +document.

+ + + + + + + +
-~/.bash_login, -or +

blank

 -~/.profile. -By default, -bash +

A space or tab.

 +
-reads these files when it is invoked as a login shell (see -INVOCATION +

whitespace

- -below). -
--norc +

A character belonging to the +space character class in the current locale, or for +which isspace(3) returns true.

-
-Do not read and execute the personal initialization file + + + + + + + + + + + +
-~/.bashrc -if the shell is interactive. -This option is on by default if the shell is invoked as -sh. +

word

 -
--posix -
-Enable posix mode; -change the behavior of bash -where the default operation differs from the -POSIX -standard to match the standard. -
--restricted +

A sequence of characters considered as a single unit by +the shell. Also known as a token.

-
-The shell becomes restricted (see -RESTRICTED SHELL - -below). -
--verbose +

name

 -
-Equivalent to -v. -
--version -
-Show version information for this instance of -bash +

A word consisting only of alphanumeric characters +and underscores, and beginning with an alphabetic character +or an underscore. Also referred to as an +identifier.

-on the standard output and exit successfully. -
-  -

ARGUMENTS

+

metacharacter

-If arguments remain after option processing, and neither the --c +

A character that, when +unquoted, separates words. One of the following:
+| & ; ( ) < > space tab newline

-nor the --s +

control operator

-option has been supplied, the first argument is treated as -the name of a file containing shell commands (a shell script). -When -bash +

A token that performs a +control function. It is one of the following symbols: +
+|| & && ; ;; ;& ;;& ( ) | |& +<newline>

-is invoked in this fashion, -$0 +

RESERVED WORDS + +

-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. -Bash +

Reserved +words are words that have a special meaning to the +shell. The following words are recognized as reserved when +unquoted and either

-first attempts to open the file in the current directory, -and, if no file is found, searches the directories in -PATH + + + + + + + + + + + + + + + + + + + + + + + + + + +
- -for the script. -  -

INVOCATION

-A login shell is one whose first character of argument zero is a --, +

•

 -or one started with the ---login -option. -

+

the first word of a command (see SHELL +GRAMMAR below);

-An interactive shell is one started without non-option arguments -(unless -s is specified) -and without the --c -option, -and whose standard input and standard error are -both connected to terminals (as determined by -isatty(3)), +

•

 -or one started with the --i -option. -Bash +

the first word following a reserved word other than +case, for, select, or in;

-sets -PS1 - -and -$- +

•

 -includes -i -if the shell is interactive, -so a shell script or a startup file can test this state. -

+

the third word of a case command (only in +is valid);

-The following paragraphs describe how -bash -executes its startup files. -If any of the files exist but cannot be read, -bash +

•

 -reports an error. -Tildes are expanded in filenames as described below under -Tilde Expansion -in the -EXPANSION +

the third word of a for or select command +(only in and do are valid);

- -section. -

-When -bash +

•

 -is invoked as an interactive login shell, or as a non-interactive shell -with the --login option, it first reads and -executes commands from the file -/etc/profile, +

following a control operator.

-if that file exists. -After reading that file, it looks for +

The shell will +also recognize reserved words where the syntax of a command +specifically requires the reserved word as the only correct +token.

+ +

The following +are reserved words:

+ +

! case coproc +do done elif else esac fi for function if in select then +until while { } time [[ ]]

+ +

SHELL GRAMMAR + +

+ + +

This section +describes the syntax of the various forms of shell +commands.

+ +

Simple Commands + +

+ + +

A simple +command is a sequence of optional variable assignments +followed by blank-separated words and redirections, +and terminated by a control operator. 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.

+ +

The return value +of a simple command is its exit status, or +128+n if the command is terminated by signal +n.

+ +

Pipelines + +

-~/.bash_profile, +

A +pipeline is a sequence of one or more commands +separated by one of the control operators | or +|&. The format for a pipeline is:

+ +

[time +[−p]] [ ! ] command1 [ +[|⎪|&] command2 ... ]

+ +

The standard +output of command1 is connected via a pipe to the +standard input of command2. This connection is +performed before any redirections specified by the +command1(see REDIRECTION +below). If |& is the pipeline operator, +command1’s standard error, in addition to its +standard output, is connected to command2’s +standard input through the pipe; it is shorthand for +2>&1 |. This implicit redirection of the +standard error to the standard output is performed after any +redirections specified by command1.

+ +

The return +status of a pipeline is the exit status of the last command, +unless the pipefail option is enabled. If +pipefail is enabled, the pipeline’s return +status is the value of the last (rightmost) command to exit +with a non-zero status, or zero if all commands exit +successfully. If the reserved word ! precedes a +pipeline, the exit status of that pipeline is the logical +negation of the exit status as described above. If a +pipeline is executed synchronously, the shell waits for all +commands in the pipeline to terminate before returning a +value.

+ +

If the +time reserved word precedes a pipeline, the shell +reports the elapsed as well as user and system time consumed +by its execution when the pipeline terminates. The +−p option changes the output format to that +specified by POSIX . When the shell is in +posix mode, it does not recognize time as a reserved +word if the next token begins with a “−”. +The value of the TIMEFORMAT variable +is a format string that specifies how the timing information +should be displayed; see the description of +TIMEFORMAT below under Shell +Variables.

+ +

When the shell +is in posix mode, time may appear by itself as the +only word in a simple command. In this case, the shell +displays the total user and system time consumed by the +shell and its children. The TIMEFORMAT +variable specifies the format of the time information.

+ +

Each command in +a multi-command pipeline, where pipes are created, is +executed in a subshell, which is a separate process. +See COMMAND EXECUTION ENVIRONMENT for +a description of subshells and a subshell environment. If +the lastpipe option is enabled using the shopt +builtin (see the description of shopt below), and job +control is not active, the last element of a pipeline may be +run by the shell process.

+ +

Lists + +

+ + +

A list is +a sequence of one or more AND or OR lists separated by one +of the operators ;, &, or +<newline>, and optionally terminated by one of +those three characters.

+ +

AND and OR lists +are sequences of one or more pipelines separated by the +&& and || control operators, +respectively. AND and OR lists are executed with left +associativity.

+ +

An AND list has +the form

+ + +

command1 +&& command2

+ +

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

+ +

An OR list has +the form

+ + +

command1 +|| command2

+ +

command2 +is executed if, and only if, command1 returns a +non-zero exit status. The return status of AND and OR lists +is the exit status of the last command executed in the +list.

+ +

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

+ +

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

+ +

If a command is +terminated by the control operator &, the shell +executes the command in the background in a subshell. +The shell does not wait for the command to finish, and the +return status is 0. These are referred to as +asynchronous commands. Commands separated or +terminated by ; (or an equivalent +<newline>) are executed sequentially; the shell +waits for each command to terminate in turn.

+ +

The return +status of a list is the exit status of the last command +executed.

+ +

Compound Commands + +

+ + +

A compound +command is one of the following. In most cases a +list 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.

+ + + + + + + +
+ + +

(list)

 + + +

list is executed in a +subshell (see COMMAND EXECUTION +ENVIRONMENT below for a description of a +subshell environment). 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 list.

+ +

{ list; }

+ +

list is executed in the +current shell environment. list must be terminated +with a newline or semicolon. This is known as a group +command. The return status is the exit status of +list.

+ +

Note that +unlike the metacharacters ( and ), { +and } are reserved words 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 +list by whitespace or another shell +metacharacter.

+ +

((expression))

+ +

The arithmetic +expression is evaluated according to the rules +described below under ARITHMETIC +EVALUATION. If the value of the +expression is non-zero, the return status is 0; otherwise +the return status is 1. The expression undergoes the +same expansions as if it were within double quotes, but +unescaped double quote characters in expression are +not treated specially and are removed. Since this can +potentially result in empty strings, this command treats +those as expressions that evaluate to 0.

+ +

[[ expression +]]

+ +

Evaluate the conditional +expression expression and return a status of zero +(true) or non-zero (false). Expressions are composed of the +primaries described below under CONDITIONAL +EXPRESSIONS. The words between +the [[ and ]] do not undergo word splitting +and pathname expansion. The shell performs tilde expansion, +parameter and variable expansion, arithmetic expansion, +command substitution, process substitution, and quote +removal on those words. Conditional operators such as +−f must be unquoted to be recognized as +primaries.

+ +

When used with +[[, the < and > operators sort +lexicographically using the current locale.

+ +

When the +== and != operators are used, the string to +the right of the operator is considered a pattern and +matched according to the rules described below under +Pattern Matching, as if the extglob shell +option were enabled. The = operator is equivalent to +==. If the nocasematch shell option is +enabled, the match is performed without regard to the case +of alphabetic characters. The return value is 0 if the +string matches (==) or does not match (!=) the +pattern, and 1 otherwise. If any part of the pattern is +quoted, the quoted portion is matched as a string: every +character in the quoted portion matches itself, instead of +having any special pattern matching meaning.

+ +

An additional +binary operator, =~, is available, with the same +precedence as == and !=. When it is used, the +string to the right of the operator is considered a +POSIX extended regular expression and matched +accordingly (using the POSIX regcomp +and regexec interfaces usually described in +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 +nocasematch shell option is enabled, the match is +performed without regard to the case of alphabetic +characters.

+ +

If any part of +the pattern is quoted, the quoted portion is matched +literally, as above. If the pattern is stored in a shell +variable, quoting the variable expansion forces the entire +pattern to be matched literally. Treat bracket expressions +in regular expressions carefully, since normal quoting and +pattern characters lose their meanings between brackets.

+ +

The match +succeeds if the pattern matches any part of the string. +Anchor the pattern using the ^ and $ regular +expression operators to force it to match the entire +string.

+ +

The array +variable BASH_REMATCH records which +parts of the string matched the pattern. The element of +BASH_REMATCH with index 0 contains the +portion of the string matching the entire regular +expression. Substrings matched by parenthesized +subexpressions within the regular expression are saved in +the remaining BASH_REMATCH indices. +The element of BASH_REMATCH with index +n is the portion of the string matching the +nth parenthesized subexpression. Bash sets +BASH_REMATCH in the global scope; +declaring it as a local variable will lead to unexpected +results.

+ +

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

+ +

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

+ +

! expression

+ +

True if expression is +false.

+ +

expression1 +&& expression2

+ +

True if both expression1 +and expression2 are true.

+ +

expression1 || +expression2

+ +

True if either +expression1 or expression2 is true.

+ +

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

+ +

for name [ [ +in word ... ] ; ] do list ; +done

+ +

First, expand the list of words +following in, generating a list of items. Then, the +variable name is set to each element of this list in +turn, and list is executed each time. If the +in word is omitted, the for command +executes list once for each positional parameter that +is set (see PARAMETERS below). The +return status is the exit status of the last command that +executes. If the expansion of the items following in +results in an empty list, no commands are executed, and the +return status is 0.

+ +

for (( expr1 ; +expr2 ; expr3 )) [;] do list ; +done

+ +

First, evaluate the arithmetic +expression expr1 according to the rules described +below under ARITHMETIC +EVALUATION. Then, repeatedly +evaluate the arithmetic expression expr2 until it +evaluates to zero. Each time expr2 evaluates to a +non-zero value, execute list and evaluate the +arithmetic expression expr3. If any expression is +omitted, it behaves as if it evaluates to 1. The return +value is the exit status of the last command in list +that is executed, or non-zero if any of the expressions is +invalid.

+ +

Use the +break and continue builtins (see +SHELL BUILTIN COMMANDS below) to +control loop execution.

+ +

select name [ [ +in word ... ] ; ] do list ; +done

+ +

First, expand the list of words +following in, generating a list of items, and print +the set of expanded words the standard error, each preceded +by a number. If the in word is omitted, print +the positional parameters (see +PARAMETERS below). select then +displays the PS3 prompt and reads a +line from the standard input. If the line consists of a +number corresponding to one of the displayed words, then +select sets the value of name to that word. If +the line is empty, select displays the words and +prompt again. If EOF is read, select completes and +returns 1. Any other value sets name to null. The +line read is saved in the variable +REPLY. The list +is executed after each selection until a break +command is executed. The exit status of select is the +exit status of the last command executed in list, or +zero if no commands were executed.

+ +

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

+ +

A case command first +expands word, and tries to match it against each +pattern in turn, proceeding from first to last, using +the matching rules described under Pattern Matching +below. The word is expanded using tilde expansion, +parameter and variable expansion, arithmetic expansion, +command substitution, process substitution and quote +removal. Each pattern examined is expanded using +tilde expansion, parameter and variable expansion, +arithmetic expansion, command substitution, process +substitution, and quote removal. If the nocasematch +shell option is enabled, the match is performed without +regard to the case of alphabetic characters.

+ +

A pattern +list is a set of one or more patterns separated by +|, and terminated by the ) operator. A case +clause is a pattern list and an associated +list, terminated by ;;, ;&, or +;;&. The terminator is optional for the last +clause preceding esac. There may be an arbitrary +number of case clauses. The first pattern that matches +determines the list that is executed.

+ +

When a match is +found, case executes the corresponding list. +If the ;; operator terminates the case clause, the +case command completes after the first match. Using +the ;& terminator continues execution with the +list associated with the next clause, if any. Using +the ;;& terminator causes the shell to test the +pattern list in the next clause, if any, and execute any +associated list if the match succeeds, continuing the +case statement execution as if the pattern list had not +matched.

+ +

The exit status +is zero if no pattern matches. Otherwise, it is the exit +status of the last command executed in the last list +executed.

+ +

if list; +then list; [ elif list; +then list; ] ... [ else list; ] +fi

+ +

The if list is +executed. If its exit status is zero, the then +list is executed. Otherwise, each elif +list is executed in turn, and if its exit status is +zero, the corresponding then list is executed +and the command completes. Otherwise, the else +list is executed, if present. The exit status is the +exit status of the last command executed, or zero if no +condition tested true.

+ +

while list-1; +do list-2; done
+until list-1; do list-2; +done

+ +

The while command +continuously executes the list list-2 as long as the +last command in the list list-1 returns an exit +status of zero. The until command is identical to the +while command, except that the test is negated: +list-2 is executed as long as the last command in +list-1 returns a non-zero exit status. The exit +status of the while and until commands is the +exit status of the last command executed in list-2, +or zero if none was executed.

+ +

Coprocesses + +

+ + +

A +coprocess is a shell command preceded by the +coproc reserved word. A coprocess is executed +asynchronously in a subshell, as if the command had been +terminated with the & control operator, with a +two-way pipe established between the executing shell and the +coprocess.

+ +

The syntax for a +coprocess is:

+ +

coproc +[NAME] command [redirections]

+ +

This creates a +coprocess named NAME. command may be either a +simple command or a compound command (see above). +NAME is a shell variable name. If NAME is not +supplied, the default name is COPROC.

+ +

The recommended +form to use for a coprocess is

+ +

coproc +NAME { command [redirections]; }

+ +

This form is +preferred because simple commands result in the coprocess +always being named COPROC, and it is simpler to use +and more complete than the other compound commands.

+ +

If +command is a compound command, NAME is +optional. The word following coproc determines +whether that word is interpreted as a variable name: it is +interpreted as NAME if it is not a reserved word that +introduces a compound command. If command is a simple +command, NAME is not allowed; this is to avoid +confusion between NAME and the first word of the +simple command.

+ +

When the +coprocess is executed, the shell creates an array variable +(see Arrays below) named NAME in the context +of the executing shell. The standard output of +command is connected via a pipe to a file descriptor +in the executing shell, and that file descriptor is assigned +to NAME[0]. The standard input of command is +connected via a pipe to a file descriptor in the executing +shell, and that file descriptor is assigned to +NAME[1]. This pipe is established before any +redirections specified by the command (see +REDIRECTION below). The file +descriptors can be utilized as arguments to shell commands +and redirections using standard word expansions. Other than +those created to execute command and process substitutions, +the file descriptors are not available in subshells.

+ +

The process ID +of the shell spawned to execute the coprocess is available +as the value of the variable NAME_PID. The +wait builtin may be used to wait for the coprocess to +terminate.

+ +

Since the +coprocess is created as an asynchronous command, the +coproc command always returns success. The return +status of a coprocess is the exit status of +command.

+ +

Shell Function Definitions + +

+ + +

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:
+fname () compound−command +[redirection]
+function fname [()] compound−command +[redirection]

+ +

This defines a function named +fname. The reserved word function is optional. +If the function reserved word is supplied, the +parentheses are optional. The body of the function is +the compound command compound−command (see +Compound Commands above). That command is usually a +list of commands between { and }, but may be any +command listed under Compound Commands above. If the +function reserved word is used, but the parentheses +are not supplied, the braces are recommended. +compound−command is executed whenever +fname is specified as the name of a simple command. +When in posix mode, fname must be a valid shell +name and may not be the name of one of the +POSIX special builtins. In default +mode, a function name can be any unquoted shell word that +does not contain $.

+ +

Any redirections +(see 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 +FUNCTIONS below.)

+ +

COMMENTS + +

+ + +

In a +non-interactive shell, or an interactive shell in which the +interactive_comments option to the shopt +builtin is enabled (see SHELL BUILTIN +COMMANDS below), a word beginning with # +introduces a comment. A word begins at the beginning of a +line, after unquoted whitespace, or after an operator. The +comment causes that word and all remaining characters on +that line to be ignored. An interactive shell without the +interactive_comments option enabled does not allow +comments. The interactive_comments option is enabled +by default in interactive shells.

+ +

QUOTING + +

+ + +

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 +metacharacters listed above under +DEFINITIONS has special meaning to the +shell and must be quoted if it is to represent itself.

+ +

When the command +history expansion facilities are being used (see +HISTORY EXPANSION below), the +history expansion character, usually !, must +be quoted to prevent history expansion.

+ +

There are four +quoting mechanisms: the escape character, single +quotes, double quotes, and dollar-single quotes.

+ +

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

+ +

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.

+ +

Enclosing +characters in double quotes preserves the literal value of +all characters within the quotes, with the exception of +$, `, \, and, when history expansion is +enabled, !. When the shell is in posix mode, the +! has no special meaning within double quotes, even +when history expansion is enabled. The characters $ +and ` retain their special meaning within double +quotes. The backslash retains its special meaning only when +followed by one of the following characters: $, +`, ", \, or +<newline>. Backslashes preceding characters +without a special meaning are left unmodified.

+ +

A double quote +may be quoted within double quotes by preceding it with a +backslash. If enabled, history expansion will be performed +unless an ! appearing in double quotes is escaped +using a backslash. The backslash preceding the ! is +not removed.

-~/.bash_login, +

The special +parameters * and @ have special meaning when +in double quotes (see PARAMETERS +below).

-and +

Character +sequences of the form $'string' are treated as +a special variant of single quotes. The sequence expands to +string, with backslash-escaped characters in +string replaced as specified by the ANSI C standard. +Backslash escape sequences, if present, are decoded as +follows:

-~/.profile, + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
-in that order, and reads -and executes commands from the first one that exists and is readable. -The ---noprofile -option may be used when the shell is started to inhibit this behavior. -

+

\a

 -When an interactive login shell exits, -or a non-interactive login shell executes the exit builtin command, -bash -reads and executes commands from the file +

alert (bell)

-~/.bash_logout, -if it exists. -

+

\b

 -When an interactive shell that is not a login shell is started, -bash -reads and executes commands from +

backspace

-~/.bashrc, -if that file exists. -The ---norc +

\e

 +
-option inhibits this behavior. -The --rcfile file option causes -bash -to use file instead of +

\E

 -~/.bashrc. -

+

an escape character

-When -bash -is started non-interactively, to run a shell script, for example, it -looks for the variable -BASH_ENV +

\f

 - -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: -

+

form feed

-
-if [ -n " -$BASH_ENV" - ]; then . " -$BASH_ENV" -; fi +

\n

 - -

+

new line

-but does not use the value of the -PATH - -variable to search for the filename. -

+

\r

 -If -bash -is invoked with the name -sh, +

carriage return

-it tries to mimic the startup behavior of historical versions of -sh -as closely as possible, -while conforming to the -POSIX -standard as well. -When invoked as an interactive login shell, or a non-interactive -shell with the --login option, it first attempts to read -and execute commands from +

\t

 -/etc/profile -and +

horizontal tab

-~/.profile, -in that order. -The ---noprofile +

\v

 -option inhibits this behavior. -When invoked as an interactive shell with the name -sh, -bash +

vertical tab

-looks for the variable -ENV, - -expands its value if it is defined, and uses the -expanded value as the name of a file to read and execute. -Since a shell invoked as -sh +

\\

 -does not attempt to read and execute commands from any other startup -files, the ---rcfile -option has no effect. -A non-interactive shell invoked with the name -sh +

backslash

-does not attempt to read any other startup files. -

-When invoked as -sh, +

\'

 -bash -enters posix mode after reading the startup files. -

+

single quote

-When -bash -is started in posix mode, as with the ---posix +

\"

 -command line option, it follows the -POSIX -standard for startup files. -In this mode, interactive shells expand the -ENV - -variable and read and execute commands from the file -whose name is the expanded value. -No other startup files are read. -

+

double quote

-Bash -attempts to determine when it is being run with its standard input -connected to a network connection, as when executed by -the historical and rarely-seen remote shell daemon, usually rshd, -or the secure shell daemon sshd. -If -bash +

\?

 -determines it is being run non-interactively in this fashion, -it reads and executes commands from -~/.bashrc, +

question mark

-if that file exists and is readable. -Bash -does not read this file if invoked as sh. -The ---norc +

\nnn

 -option inhibits this behavior, and the ---rcfile -option makes bash use a different file instead of +

The eight-bit character whose value is the octal value +nnn (one to three octal digits).

-~/.bashrc, -but neither -rshd nor sshd generally invoke the shell with those options -or allow them to be specified. -

+

\xHH

 -If the shell is started with the effective user (group) id not equal to the -real user (group) id, and the -p option is not supplied, no startup -files are read, shell functions are not inherited from the environment, the -SHELLOPTS, - -BASHOPTS, +

The eight-bit character whose value is the hexadecimal +value HH (one or two hex digits).

- -CDPATH, - -and -GLOBIGNORE +

\uHHHH

 - -variables, if they appear in the environment, are ignored, -and the effective user id is set to the real user id. -If the -p option is supplied at invocation, the startup behavior is -the same, but the effective user id is not reset. -  -

DEFINITIONS

-The following definitions are used throughout the rest of this -document. +

The Unicode (ISO/IEC 10646) character whose value is the +hexadecimal value HHHH (one to four hex digits).

-
-
blank +

\UHHHHHHHH

-
-A space or tab. -
whitespace +

The Unicode (ISO/IEC 10646) +character whose value is the hexadecimal value +HHHHHHHH (one to eight hex digits).

-
-A character belonging to the space character class in the -current locale, or for which isspace(3) returns true. -
word + + + + + + + +
-
-A sequence of characters considered as a single unit by the shell. -Also known as a -token. -
name +

\cx

 + + +

A control-x character.

 +
+ +

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

+ +

Translating Strings + +

+ + +

A double-quoted +string preceded by a dollar sign +($"string") causes the string to be +translated according to the current locale. The +gettext infrastructure performs the lookup and +translation, using the LC_MESSAGES, +TEXTDOMAINDIR, and TEXTDOMAIN shell variables. +If the current locale is C or POSIX, if there +are no translations available, or if the string is not +translated, the dollar sign is ignored, and the string is +treated as double-quoted as described above. This is a form +of double quoting, so the string remains double-quoted by +default, whether or not it is translated and replaced. If +the noexpand_translation option is enabled using the +shopt builtin, translated strings are single-quoted +instead of double-quoted. See the description of +shopt below under SHELL BUILTIN +COMMANDS.

+ +

PARAMETERS + +

+ + +

A +parameter is an entity that stores values. It can be +a name, a number, or one of the special characters +listed below under Special Parameters. A +variable is a parameter denoted by a name. A +variable has a value and zero or more +attributes. Attributes are assigned using the +declare builtin command (see declare below in +SHELL BUILTIN +COMMANDS). The export and +readonly builtins assign specific attributes.

+ +

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

+ +

A +variable is assigned to using a statement of the +form

+ + +

name=[value]

+ +

If value +is not given, the variable is assigned the null string. All +values undergo tilde expansion, parameter and +variable expansion, command substitution, arithmetic +expansion, and quote removal (see +EXPANSION below). If the variable has +its integer attribute set, then value is +evaluated as an arithmetic expression even if the +$((...)) expansion is not used (see +Arithmetic Expansion below). Word splitting and +pathname expansion are not performed. Assignment statements +may also appear as arguments to the alias, +declare, typeset, export, +readonly, and local builtin commands +(declaration commands). When in posix mode, these +builtins may appear in a command after one or more instances +of the 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, the “+=” operator +appends to or adds to the variable’s previous value. +This includes arguments to declaration commands such +as declare that accept assignment statements. When +“+=” is applied to a variable for which the +integer attribute has been set, the variable’s +current value and value are each evaluated as +arithmetic expressions, and the sum of the results is +assigned as the variable’s value. The current value is +usually an integer constant, but may be an expression. When +“+=” is applied to an array variable using +compound assignment (see 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, value is expanded and +appended to the variable’s value.

+ +

A variable can +be assigned the nameref attribute using the +−n option to the declare or local +builtin commands (see the descriptions of declare and +local below) to create a nameref, or a +reference to another variable. This allows variables to be +manipulated indirectly. Whenever the nameref variable is +referenced, assigned to, unset, or has its attributes +modified (other than using or changing the nameref +attribute itself), the operation is actually performed on +the variable specified by the nameref variable’s +value. A nameref is commonly used within shell functions to +refer to a variable whose name is passed as an argument to +the function. For instance, if a variable name is passed to +a shell function as its first argument, running

+ +

declare +−n ref=$1

+ +

inside the +function creates a local nameref variable ref whose +value is the variable name passed as the first argument. +References and assignments to ref, and changes to its +attributes, are treated as references, assignments, and +attribute modifications to the variable whose name was +passed as $1. If the control variable in a for +loop has the nameref attribute, the list of words can be a +list of shell variables, and a name reference is established +for each word in the list, in turn, when the loop is +executed. Array variables cannot be given the nameref +attribute. However, nameref variables can reference array +variables and subscripted array variables. Namerefs can be +unset using the −n option to the unset +builtin. Otherwise, if unset is executed with the +name of a nameref variable as an argument, the variable +referenced by the nameref variable is unset.

+ +

When the shell +starts, it reads its environment and creates a shell +variable from each environment variable that has a valid +name, as described below (see +ENVIRONMENT).

+ +

Positional Parameters + +

+ + +

A positional +parameter is a parameter denoted by one or more digits, +other than the single digit 0. Positional parameters are +assigned from the shell’s arguments when it is +invoked, and may be reassigned using the set builtin +command. Positional parameters may not be assigned to with +assignment statements. The positional parameters are +temporarily replaced when a shell function is executed (see +FUNCTIONS below).

+ +

When a +positional parameter consisting of more than a single digit +is expanded, it must be enclosed in braces (see +EXPANSION below). Without braces, a +digit following $ can only refer to one of the first nine +positional parameters ($1−$9) or the special +parameter $0 (see the next section).

+ +

Special Parameters + +

+ + +

The shell treats +several parameters specially. These parameters may only be +referenced; assignment to them is not allowed. Special +parameters are denoted by one of the following +characters.

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

*

 + + +

($*) Expands to the +positional parameters, starting from one. When the expansion +is not within double quotes, each positional parameter +expands to a separate word. In contexts where word +expansions are performed, those words are subject to further +word splitting and pathname expansion. When the expansion +occurs within double quotes, it expands to a single word +with the value of each parameter separated by the first +character of the IFS variable. That +is, "$*" is equivalent to +"$1c$2c...", +where c is the first character of the value of the +IFS variable. If +IFS is unset, the parameters are +separated by spaces. If IFS is null, +the parameters are joined without intervening +separators.

+ + +

@

 + + +

($@) Expands to the positional parameters, +starting from one. In contexts where word splitting is +performed, this expands each positional parameter to a +separate word; if not within double quotes, these words are +subject to word splitting. In contexts where word splitting +is not performed, such as the value portion of an assignment +statement, this expands to a single word with each +positional parameter separated by a space. When the +expansion occurs within double quotes, and word splitting is +performed, each parameter expands to a separate word. That +is, "$@" is equivalent to +"$1" "$2" ... If the +double-quoted expansion occurs within a word, the expansion +of the first parameter is joined with the expansion of the +beginning part of the original word, and the expansion of +the last parameter is joined with the expansion of the last +part of the original word. When there are no positional +parameters, "$@" and $@ expand to +nothing (i.e., they are removed).

+ + +

#

 + + +

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

+ + +

?

 + + +

($?) Expands to the exit status of the most +recently executed command.

+ + +

−

 + + +

($−) Expands to the current option flags as +specified upon invocation, by the set builtin +command, or those set by the shell itself (such as the +−i option).

+ + +

$

 + + +

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

+ + +

!

 + + +

($!)Expands to the process ID of the job most +recently placed into the background, whether executed as an +asynchronous command or using the bg builtin (see +JOB CONTROL below).

-
-A -word -consisting only of alphanumeric characters and underscores, and -beginning with an alphabetic character or an underscore. Also -referred to as an -identifier. +

0

 -
metacharacter -
-A character that, when unquoted, separates words. -One of the following: -
+

($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, $0 is set to the +name of that file. If bash is started with the +−c option, then $0 is set to the first +argument after the string to be executed, if one is present. +Otherwise, it is set to the filename used to invoke +bash, as given by argument zero.

+ +

Shell Variables + +

+ + +

The shell sets +following variables:

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

_

 + + +

($_, an underscore) This +has a number of meanings depending on context. At shell +startup, _ is set to the pathname used to invoke the +shell or shell script being executed as passed in the +environment or argument list. Subsequently, it expands to +the last argument to the previous simple command executed in +the foreground, after expansion. It is also set to the full +pathname used to invoke each command executed and placed in +the environment exported to that command. When checking +mail, $_ expands to the name of the mail file +currently being checked.

+ + +

BASH

 + + +

Expands to the full filename used to invoke this +instance of bash.

+ +

BASHOPTS

+ +

A colon-separated list of +enabled shell options. Each word in the list is a valid +argument for the −s option to the shopt +builtin command (see SHELL BUILTIN +COMMANDS below). The options appearing in +BASHOPTS are those reported as +on by shopt. If this variable is in the +environment when bash starts up, the shell enables +each option in the list before reading any startup files. If +this variable is exported, child shells will enable each +option in the list. This variable is read-only.

+ +

BASHPID

+ +

Expands to the process ID of +the current bash process. This differs from $$ +under certain circumstances, such as subshells that do not +require bash to be re-initialized. Assignments to +BASHPID have no effect. If +BASHPID is unset, it loses its special +properties, even if it is subsequently reset.

+ +

BASH_ALIASES

+ +

An associative array variable +whose members correspond to the internal list of aliases as +maintained by the alias builtin. Elements added to +this array appear in the alias list; however, unsetting +array elements currently does not remove aliases from the +alias list. If BASH_ALIASES is unset, +it loses its special properties, even if it is subsequently +reset.

+ +

BASH_ARGC

+ +

An array variable whose values +are the number of parameters in each frame of the current +bash execution call stack. The number of parameters +to the current subroutine (shell function or script executed +with . or source) is at the top of the stack. +When a subroutine is executed, the number of parameters +passed is pushed onto +BASH_ARGC. The shell +sets BASH_ARGC only when in extended +debugging mode (see the description of the extdebug +option to the shopt builtin below). Setting +extdebug after the shell has started to execute a +script, or referencing this variable when extdebug is +not set, may result in inconsistent values. Assignments to +BASH_ARGC have no effect, and it may +not be unset.

+ +

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 shell pushes the supplied parameters onto +BASH_ARGV. The shell +sets BASH_ARGV only when in extended +debugging mode (see the description of the extdebug +option to the shopt builtin below). Setting +extdebug after the shell has started to execute a +script, or referencing this variable when extdebug is +not set, may result in inconsistent values. Assignments to +BASH_ARGV have no effect, and it may +not be unset.

+ +

BASH_ARGV0

+ +

When referenced, this variable +expands to the name of the shell or shell script (identical +to $0; see the description of special parameter 0 +above). Assigning a value to +BASH_ARGV0 sets $0 to the same +value. If BASH_ARGV0 is unset, it +loses its special properties, even if it is subsequently +reset.

+ +

BASH_CMDS

+ +

An associative array variable +whose members correspond to the internal hash table of +commands as maintained by the hash builtin. Adding +elements to this array makes them appear in the hash table; +however, unsetting array elements currently does not remove +command names from the hash table. If +BASH_CMDS is unset, it loses its +special properties, even if it is subsequently reset.

+ +

BASH_COMMAND

+ +

Expands to 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. If BASH_COMMAND is unset, it +loses its special properties, even if it is subsequently +reset.

+ + +

BASH_EXECUTION_STRING

+ +

The command argument to the +−c invocation option.

+ +

BASH_LINENO

+ +

An array variable whose members +are the line numbers in source files where each +corresponding member of FUNCNAME was +invoked. ${BASH_LINENO[$i]} is the line +number in the source file +(${BASH_SOURCE[$i+1]}) where +${FUNCNAME[$i]} was called (or +${BASH_LINENO[$i−1]} if +referenced within another shell function). Use +LINENO to obtain the current line +number. Assignments to BASH_LINENO +have no effect, and it may not be unset.

+ +

BASH_LOADABLES_PATH

+ +

A colon-separated list of +directories in which the enable command looks for +dynamically loadable builtins.

+ +

BASH_MONOSECONDS

+ +

Each time this variable is +referenced, it expands to the value returned by the +system’s monotonic clock, if one is available. If +there is no monotonic clock, this is equivalent to +EPOCHSECONDS. If +BASH_MONOSECONDS is unset, it loses +its special properties, even if it is subsequently +reset.

+ +

BASH_REMATCH

+ +

An array variable whose members +are assigned by the =~ binary operator to the +[[ conditional command. The element with index 0 is +the portion of the string matching the entire regular +expression. The element with index n is the portion +of the string matching the nth parenthesized +subexpression.

+ +

BASH_SOURCE

+ +

An array variable whose members +are the source filenames where the corresponding shell +function names in the FUNCNAME array +variable are defined. The shell function +${FUNCNAME[$i]} is defined in the file +${BASH_SOURCE[$i]} and called from +${BASH_SOURCE[$i+1]}. Assignments to +BASH_SOURCE have no effect, and it may +not be unset.

-
-

+

BASH_SUBSHELL

-| & ; ( ) < > space tab newline +

Incremented by one within each +subshell or subshell environment when the shell begins +executing in that environment. The initial value is 0. If +BASH_SUBSHELL is unset, it loses its +special properties, even if it is subsequently reset.

-
+

BASH_TRAPSIG

-
control operator +

Set to the signal number +corresponding to the trap action being executed during its +execution. See the description of trap under +SHELL BUILTIN COMMANDS below for +information about signal numbers and trap execution.

-
-A token that performs a control function. -It is one of the following symbols: -
-

+

BASH_VERSINFO

-|| & && ; ;; ;& ;;& ( ) | |& <newline> +

A readonly array variable whose +members hold version information for this instance of +bash. The values assigned to the array members are as +follows:

-
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
- -  -

RESERVED WORDS

+

BASH_VERSINFO[0]

 -Reserved words 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 command (see -SHELL GRAMMAR - -below), the third word of a -case +

The major version number (the release).

 +
-or -select -command -(only in is valid), or the third word of a -for +

BASH_VERSINFO[1]

 -command (only in and do are valid): -
-

+

The minor version number (the version).

 +
- - -! case coproc do done elif else esac fi for function if in select then until while { } time [[ ]] - +

BASH_VERSINFO[2]

 -  -

SHELL GRAMMAR

+

The patch level.

 +
-This section describes the syntax of the various forms of shell commands. -  -

Simple Commands

-A simple command is a sequence of optional variable assignments -followed by blank-separated words and redirections, and -terminated by a control operator. -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. -

+

BASH_VERSINFO[3]

 -The return value of a simple command is its exit status, or -128+n if the command is terminated by signal -n. -  -

Pipelines

+

The build version.

 +
-A pipeline is a sequence of one or more commands separated by -one of the control operators -| -or |&. -The format for a pipeline is: -
-

+

BASH_VERSINFO[4]

 -[time [-p]] [ ! ] command1 [ [|||&] command2 ... ] - -

+

The release status (e.g., beta).

 +
-The standard output of -command1 -is connected via a pipe to the standard input of -command2. +

BASH_VERSINFO[5]

 -This connection is performed before any redirections specified by the -command1(see -REDIRECTION +

The value of +MACHTYPE.

 +
- -below). -If |& is the pipeline operator, -command1's standard error, in addition to its -standard output, is connected to -command2's standard input through the pipe; -it is shorthand for 2>&1 |. -This implicit redirection of the standard error to the standard output is -performed after any redirections specified by command1. -

+

BASH_VERSION

-The return status of a pipeline is the exit status of the last -command, unless the pipefail option is enabled. -If pipefail is enabled, the pipeline's return status is the -value of the last (rightmost) command to exit with a non-zero status, -or zero if all commands exit successfully. -If the reserved word -! +

Expands to a string describing +the version of this instance of bash (e.g., +5.2.37(3)-release).

-precedes a pipeline, the exit status of that pipeline is the logical -negation of the exit status as described above. -If a pipeline is executed synchronously, -the shell waits for all commands in the pipeline to -terminate before returning a value. -

+

COMP_CWORD

-If the -time +

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

-reserved word precedes a pipeline, the shell reports the -elapsed as well as user and system time consumed by its execution -when the pipeline terminates. -The -p option changes the output format to that specified by -POSIX -. -When the shell is in posix mode, it does not recognize -time as a reserved word if the next token begins with a - -The value of the -TIMEFORMAT - - -variable is a format string that specifies how the timing -information should be displayed; see the description of -TIMEFORMAT - - -below under -Shell Variables. - -

+

COMP_KEY

-When the shell is in posix mode, time -may appear by itself as the only word in a simple command. -In this case, the shell displays the -total user and system time consumed by the shell and its children. -The -TIMEFORMAT - - -variable specifies the format of the time information. -

- -Each command in a multi-command pipeline, -where pipes are created, -is executed in a subshell, which is a -separate process. -See -COMMAND EXECUTION ENVIRONMENT +

The key (or final key of a key +sequence) used to invoke the current completion function. +This variable is available only in shell functions and +external commands invoked by the programmable completion +facilities (see Programmable Completion below).

- -for a description of subshells and a subshell environment. -If the lastpipe option is enabled using the shopt builtin -(see the description of shopt below), -and job control is not active, -the last element of a pipeline may be run by the shell process. -  -

Lists

+

COMP_LINE

-A list is a sequence of one or more pipelines separated by one -of the operators -;, - -&, - -&&, - -or -||, - -and optionally terminated by one of -;, - -&, - -or -<newline>. - -

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

- -A sequence of one or more newlines may appear in a list instead -of a semicolon to delimit commands. -

- -If a command is terminated by the control operator -&, - -the shell executes the command in the background -in a subshell. -The shell does not wait for the command to -finish, and the return status is 0. -These are referred to as asynchronous commands. -Commands separated by a -; - -are executed sequentially; the shell waits for each -command to terminate in turn. -The return status is the exit status of the last command executed. -

- -AND and OR lists are sequences of one or more pipelines separated by the -&& and || control operators, respectively. -AND and OR lists are executed with left associativity. -An AND list has the form -

-

- -command1 && command2 -

- -

- -command2 - -is executed if, and only if, -command1 - -returns an exit status of zero (success). -

- -An OR list has the form -

-

- -command1 || command2 -

- -

- -command2 - -is executed if, and only if, -command1 - -returns a non-zero exit status. -The return status of -AND and OR lists is the exit status of the last command -executed in the list. -  -

Compound Commands

- -A compound command is one of the following. -In most cases a list 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. -
-
(list)
-list is executed in a subshell (see -COMMAND EXECUTION ENVIRONMENT - - -below for a description of a subshell environment). -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 list. -
{ list; }
-list is executed in the current shell environment. -list must be terminated with a newline or semicolon. -This is known as a group command. -The return status is the exit status of list. -
-Note that unlike the metacharacters ( and ), { and -} are reserved words 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 -list by whitespace or another shell metacharacter. -
((expression))
-The arithmetic expression is evaluated according to the rules -described below under -ARITHMETIC EVALUATION. - - -If the value of the expression is non-zero, the return status is 0; -otherwise the return status is 1. -The expression -undergoes the same expansions -as if it were within double quotes, -but unescaped double quote characters -in expression are not treated -specially and are removed. -Since this can potentially result in empty strings, this command treats -those as expressions that evaluate to 0. -
[[ expression ]]
- -Evaluate the conditional expression expression -and return a status of zero (true) or non-zero (false). -Expressions are composed of the primaries described below under -CONDITIONAL EXPRESSIONS. - - -The words between the [[ and ]] do not undergo word splitting -and pathname expansion. -The shell performs tilde expansion, parameter and -variable expansion, arithmetic expansion, command substitution, process -substitution, and quote removal on those words. -Conditional operators such as -f must be unquoted to be recognized -as primaries. -
-When used with [[, the < and > operators sort -lexicographically using the current locale. -
-When the == and != operators are used, the string to the -right of the operator is considered a pattern and matched according -to the rules described below under Pattern Matching, -as if the extglob shell option were enabled. -The = operator is equivalent to ==. -If the -nocasematch - -shell option is enabled, the match is performed without regard to the case -of alphabetic characters. -The return value is 0 if the string matches (==) or does not match -(!=) the pattern, and 1 otherwise. -If any part of the pattern is quoted, the quoted portion is matched -as a string: every character in the quoted portion matches itself, -instead of having any special pattern matching meaning. -
-An additional binary operator, =~, is available, with the same -precedence as == and !=. -When it is used, the string to the right of the operator is considered -a -POSIX -extended regular expression and matched accordingly -(using the -POSIX -regcomp and regexec interfaces -usually described in -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 -nocasematch - -shell option is enabled, the match is performed without regard to the case -of alphabetic characters. -
-If any part of the pattern is quoted, the quoted portion is matched literally, -as above. -If the pattern is stored in a shell variable, quoting the variable -expansion forces the entire pattern to be matched literally. -Treat bracket expressions in regular expressions carefully, -since normal quoting and pattern characters lose their meanings -between brackets. -
-The match succeeds if the pattern matches any part of the string. -Anchor the pattern using the ^ and $ regular expression -operators to force it to match the entire string. -
-The array variable -BASH_REMATCH - - -records which parts of the string matched the pattern. -The element of -BASH_REMATCH - - -with index 0 contains the portion of -the string matching the entire regular expression. -Substrings matched by parenthesized subexpressions within the regular -expression are saved in the remaining -BASH_REMATCH - - -indices. -The element of -BASH_REMATCH - - -with index n is the portion of the -string matching the nth parenthesized subexpression. -Bash sets -BASH_REMATCH - - -in the global scope; declaring it as a local variable will lead to -unexpected results. -
-Expressions may be combined using the following operators, listed -in decreasing order of precedence: -
-
- -
-
( expression ) - -
-Returns the value of expression. -This may be used to override the normal precedence of operators. -
! expression - -
-True if -expression - -is false. -
expression1 && expression2
-True if both -expression1 - -and -expression2 - -are true. -
expression1 || expression2
-True if either -expression1 - -or -expression2 - -is true. - -
-

- -The && and || -operators do not evaluate expression2 if the value of -expression1 is sufficient to determine the return value of -the entire conditional expression. -

- -
for name [ [ in word ... ] ; ] do list ; done
-First, expand The list of words following in, generating a list -of items. -Then, the variable name is set to each element of this list -in turn, and list is executed each time. -If the in word is omitted, the for command executes -list once for each positional parameter that is set (see -PARAMETERS - - -below). -The return status is the exit status of the last command that executes. -If the expansion of the items following in results in an empty -list, no commands are executed, and the return status is 0. -
for (( expr1 ; expr2 ; expr3 )) [;] do list ; done
-First, evaluate the arithmetic expression expr1 according -to the rules described below under -ARITHMETIC EVALUATION. - - -Then, repeatedly evaluate the arithmetic expression expr2 -until it evaluates to zero. -Each time expr2 evaluates to a non-zero value, -execute list -and evaluate the arithmetic expression expr3. -If any expression is omitted, it behaves as if it evaluates to 1. -The return value is the exit status of the last command in list -that is executed, or non-zero if any of the expressions is invalid. -
-Use the break and continue builtins -(see -SHELL BUILTIN COMMANDS - - -below) -to control loop execution. -
select name [ in word ] ; do list ; done
-First, expand the list of words following in, -generating a list of items, and print the set of expanded words -the standard error, each preceded by a number. -If the in -word is omitted, print the positional parameters (see -PARAMETERS - - -below). -select - -then displays the -PS3 - - -prompt and reads a line from the standard input. -If the line consists of a number corresponding to one of -the displayed words, then select sets the value of -name - -to that word. -If the line is empty, select displays the words and prompt again. -If EOF is read, select completes and returns 1. -Any other value sets -name - -to null. -The line read is saved in the variable -REPLY. - - -The -list - -is executed after each selection until a -break - -command is executed. -The exit status of -select - -is the exit status of the last command executed in -list, - -or zero if no commands were executed. -
case word in [ [(] pattern [ | pattern ] -.. ) list ;; ] ... esac
-A case command first expands word, and tries to match -it against each pattern in turn, -proceeding from first to last, -using the matching rules -described under -Pattern Matching - -below. -A pattern list is a set of one or more patterns separated by , -and the ) operator terminates the pattern list. -The word is expanded using tilde -expansion, parameter and variable expansion, arithmetic expansion, -command substitution, process substitution and quote removal. -Each pattern examined is expanded using tilde -expansion, parameter and variable expansion, arithmetic expansion, -command substitution, process substitution, and quote removal. -If the -nocasematch - -shell option is enabled, the match is performed without regard to the case -of alphabetic characters. -A clause is a pattern list and an associated list. -
-When a match is found, case executes the corresponding list. -If the ;; operator terminates the case clause, the case -command completes after the first match. -Using ;& in place of ;; causes execution to continue with -the list associated with the next pattern list. -Using ;;& in place of ;; causes the shell to test the next -pattern list in the statement, if any, and execute any associated list -if the match succeeds, -continuing the case statement execution as if the pattern list had not matched. -The exit status is zero if no pattern matches. -
-Otherwise, it is the exit status of the -last command executed in the last list executed. -
if list; then list; [ elif list; then list; ] ... [ else list; ] fi
-The -if - -list - -is executed. -If its exit status is zero, the -then list is executed. -Otherwise, each elif list is executed in turn, -and if its exit status is zero, the corresponding then list -is executed and the command completes. -Otherwise, the else list is executed, if present. -The exit status is the exit status of the -last command executed, or zero if no condition tested true. -
while list-1; do list-2; done
- -
until list-1; do list-2; done
- -The while command continuously executes the list -list-2 as long as the last command in the list list-1 returns -an exit status of zero. -The until command is identical -to the while command, except that the test is negated: -list-2 - -is executed as long as the last command in -list-1 - -returns a non-zero exit status. -The exit status of the while and until commands -is the exit status -of the last command executed in list-2, or zero if -none was executed. -
-  -

Coprocesses

- -A coprocess is a shell command preceded by the coproc reserved -word. -A coprocess is executed asynchronously in a subshell, as if the command -had been terminated with the & control operator, with a two-way pipe -established between the executing shell and the coprocess. -

- -The syntax for a coprocess is: -

-

- -coproc [NAME] command [redirections] -

- -

- -This creates a coprocess named NAME. -command may be either a simple command or a compound -command (see above). -NAME is a shell variable name. -If NAME is not supplied, the default name is COPROC. -

- -The recommended form to use for a coprocess is -

-

- -coproc NAME { command [redirections]; } -

- -

- -This form is preferred because simple commands result in the coprocess -always being named COPROC, and it is simpler to use and more complete -than the other compound commands. -

- -If command is a compound command, NAME is optional. The -word following coproc determines whether that word is interpreted -as a variable name: it is interpreted as NAME if it is not a -reserved word that introduces a compound command. -If command is a simple command, NAME is not allowed; this -is to avoid confusion between NAME and the first word of the simple -command. -

- -When the coprocess is executed, the shell creates an array variable (see -Arrays - -below) named NAME in the context of the executing shell. -The standard output of -command - -is connected via a pipe to a file descriptor in the executing shell, -and that file descriptor is assigned to NAME[0]. -The standard input of -command - -is connected via a pipe to a file descriptor in the executing shell, -and that file descriptor is assigned to NAME[1]. -This pipe is established before any redirections specified by the -command (see -REDIRECTION - - -below). -The file descriptors can be utilized as arguments to shell commands -and redirections using standard word expansions. -Other than those created to execute command and process substitutions, -the file descriptors are not available in subshells. -

- -The process ID of the shell spawned to execute the coprocess is -available as the value of the variable NAME_PID. -The wait -builtin may be used to wait for the coprocess to terminate. -

- -Since the coprocess is created as an asynchronous command, -the coproc command always returns success. -The return status of a coprocess is the exit status of command. -  -

Shell Function Definitions

- -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: -
-
fname () compound-command [redirection]
- -
function fname [()] compound-command [redirection]
- -This defines a function named fname. -The reserved word function is optional. -If the function reserved word is supplied, the parentheses are optional. -The body of the function is the compound command -compound-command - -(see Compound Commands above). -That command is usually a list of commands between { and }, but -may be any command listed under Compound Commands above. -If the function reserved word is used, but the -parentheses are not supplied, the braces are recommended. -compound-command is executed whenever fname is specified as the -name of a simple command. -When in posix mode, fname must be a valid shell name -and may not be the name of one of the -POSIX -special builtins. -In default mode, a function name can be any unquoted shell word that does -not contain $. -
-

- -Any redirections (see -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 -FUNCTIONS - - -below.) -  -

COMMENTS

- -In a non-interactive shell, or an interactive shell in which the -interactive_comments - -option to the -shopt - -builtin is enabled (see -SHELL BUILTIN COMMANDS - - -below), a word beginning with -# - -introduces a comment. -A word begins at the beginning of a line, after unquoted whitespace, or -after an operator. -The comment causes that word and all remaining characters on that line to -be ignored. -An interactive shell without the -interactive_comments - -option enabled does not allow comments. -The -interactive_comments - -option is enabled by default in interactive shells. -  -

QUOTING

- -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. -

+

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

-Each of the metacharacters listed above under -DEFINITIONS +

COMP_POINT

- -has special meaning to the shell and must be quoted if it is to -represent itself. -

+

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

-When the command history expansion facilities are being used -(see -HISTORY EXPANSION +

COMP_TYPE

- -below), the -history expansion character, usually !, must be quoted -to prevent history expansion. -

+

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

+ +

COMP_WORDBREAKS

+ +

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

+ +

COMP_WORDS

+ +

An array variable (see +Arrays below) consisting of the individual words in +the current command line. The line is split into words as +readline would split it, using +COMP_WORDBREAKS as described above. +This variable is available only in shell functions invoked +by the programmable completion facilities (see +Programmable Completion below).

+ + + + + + + +
+ + +

COPROC

 + + +

An array variable (see Arrays below) created to +hold the file descriptors for output from and input to an +unnamed coprocess (see Coprocesses above).

+ +

DIRSTACK

+ +

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

+ +

EPOCHREALTIME

+ +

Each time this parameter is +referenced, it expands to the number of seconds since the +Unix Epoch (see time(3)) as a floating-point value +with micro-second granularity. Assignments to +EPOCHREALTIME are ignored. If +EPOCHREALTIME is unset, it loses its +special properties, even if it is subsequently reset.

+ +

EPOCHSECONDS

+ +

Each time this parameter is +referenced, it expands to the number of seconds since the +Unix Epoch (see time(3)). Assignments to +EPOCHSECONDS are ignored. If +EPOCHSECONDS is unset, it loses its +special properties, even if it is subsequently reset.

+ + + + + + + +
+ + +

EUID

 + + +

Expands to the effective user ID of the current user, +initialized at shell startup. This variable is readonly.

+ +

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 “main”. This +variable exists only when a shell function is executing. +Assignments to FUNCNAME have no +effect. If FUNCNAME is unset, it loses +its special properties, even if it is subsequently +reset.

+ +

This variable +can be used with BASH_LINENO and +BASH_SOURCE. Each +element of FUNCNAME has corresponding +elements in BASH_LINENO and +BASH_SOURCE to describe the call +stack. For instance, ${FUNCNAME[$i]} +was called from the file +${BASH_SOURCE[$i+1]} at line number +${BASH_LINENO[$i]}. The caller +builtin displays the current call stack using this +information.

-There are four quoting mechanisms: the -escape character, + + + + + + +
-single quotes, double quotes, -and dollar-single quotes. -

-A non-quoted backslash (\) is the -escape character. +

GROUPS

 -It preserves the literal value of the next character that follows, -removing any special meaning it has, -with the exception of <newline>. -If a \<newline> pair appears, and the backslash is not itself quoted, -the \<newline> is treated as a line continuation (that is, it is -removed from the input stream and effectively ignored). -

-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. -

+

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

-Enclosing characters in double quotes preserves the literal value -of all characters within the quotes, with the exception of -$, +

HISTCMD

-`, +

The history number, or index in +the history list, of the current command. Assignments to +HISTCMD have no effect. If +HISTCMD is unset, it loses its special +properties, even if it is subsequently reset.

-\, +

HOSTNAME

-and, when history expansion is enabled, -!. +

Automatically set to the name +of the current host.

-When the shell is in posix mode, -the ! has no special meaning -within double quotes, even when history expansion is enabled. -The characters -$ +

HOSTTYPE

-and -` +

Automatically set to a string +that uniquely describes the type of machine on which +bash is executing. The default is +system-dependent.

-retain their special meaning within double quotes. -The backslash retains its special meaning only when followed by one of -the following characters: -$, + + + + + + +
-`, -" -, -\, +

LINENO

 -or -<newline>. -Backslashes preceding characters without a -special meaning are left unmodified. -

+

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 +LINENO is unset, it loses its special +properties, even if it is subsequently reset.

-A double quote may be quoted within double quotes by preceding it with -a backslash. -If enabled, history expansion will be performed unless an -! - -appearing in double quotes is escaped using a backslash. -The backslash preceding the -! - -is not removed. -

+

MACHTYPE

-The special parameters -* +

Automatically set to a string +that fully describes the system type on which bash is +executing, in the standard GNU cpu-company-system +format. The default is system-dependent.

-and -@ +

MAPFILE

-have special meaning when in double quotes -(see -PARAMETERS +

An array variable (see +Arrays below) created to hold the text read by the +mapfile builtin when no variable name is +supplied.

- -below). -

- -Character sequences of the form $'string' are treated -as a special variant of single quotes. -The sequence expands to string, with backslash-escaped characters -in string replaced as specified by the ANSI C standard. -Backslash escape sequences, if present, are decoded as follows: -

- -
-
\a - -
-alert (bell) -
\b - -
-backspace -
\e - -
-
\E - -
-an escape character -
\f - -
-form feed -
\n - -
-new line -
\r - -
-carriage return -
\t - -
-horizontal tab -
\v - -
-vertical tab -
\\ - -
-backslash -
\' - -
-single quote -
\ - -
-double quote -
\? - -
-question mark -
\nnn + + + + + + + + + + + + + + + + + + + + + +
-
-The eight-bit character whose value is the octal value nnn -(one to three octal digits). -
\xHH - -
-The eight-bit character whose value is the hexadecimal value HH -(one or two hex digits). -
\uHHHH - -
-The Unicode (ISO/IEC 10646) character whose value is the hexadecimal value -HHHH (one to four hex digits). -
\UHHHHHHHH -
-The Unicode (ISO/IEC 10646) character whose value is the hexadecimal value -HHHHHHHH (one to eight hex digits). -
\cx +

OLDPWD

 -
-A control-x character. - +

The previous working directory as set by the cd +command.

-

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

Translating Strings

- -A double-quoted string preceded by a dollar sign ($" -string" -) -causes the string to be translated according to the current locale. -The gettext infrastructure performs the lookup and -translation, using the LC_MESSAGES, TEXTDOMAINDIR, -and TEXTDOMAIN shell variables. -If the current locale is C or POSIX, -if there are no translations available, -or if the string is not translated, the dollar sign is ignored, -and the string is treated as double-quoted as described above. -This is a form of double quoting, so the string remains double-quoted -by default, whether or not it is translated and replaced. -If the noexpand_translation option is enabled -using the shopt builtin, -translated strings are single-quoted instead of double-quoted. -See the description of -shopt +

OPTARG

 -below under -SHELL BUILTIN COMMANDS. - -  -

PARAMETERS

+

The value of the last option argument processed by the +getopts builtin command (see SHELL BUILTIN +COMMANDS below).

-A -parameter - -is an entity that stores values. -It can be a -name, - -a number, or one of the special characters listed below under -Special Parameters. -A -variable +

OPTIND

 -is a parameter denoted by a -name. -A variable has a value and zero or more attributes. -Attributes are assigned using the -declare +

The index of the next argument to be processed by the +getopts builtin command (see SHELL BUILTIN +COMMANDS below).

-builtin command (see -declare - -below in -SHELL BUILTIN COMMANDS). - -The export and readonly builtins assign specific attributes. -

+

OSTYPE

 -A parameter is set if it has been assigned a value. -The null string is a valid value. -Once a variable is set, it may be unset only by using the -unset - -builtin command (see -SHELL BUILTIN COMMANDS - -below). -

+

Automatically set to a string that describes the +operating system on which bash is executing. The +default is system-dependent.

-A -variable +

PIPESTATUS

-is assigned to using a statement of the form -
-

+

An array variable (see +Arrays below) containing a list of exit status values +from the commands in the most-recently-executed foreground +pipeline, which may consist of only a simple command (see +SHELL GRAMMAR above). Bash sets +PIPESTATUS after executing +multi-element pipelines, timed and negated pipelines, simple +commands, subshells created with the ( operator, the +[[ and (( compound commands, and after error +conditions that result in the shell aborting command +execution.

-name=[value] -
+ + + + + + + + + + + + + + + + +
-

-If -value +

PPID

 -is not given, the variable is assigned the null string. -All -values -undergo tilde expansion, parameter and variable expansion, -command substitution, arithmetic expansion, and quote -removal (see -EXPANSION +

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

- -below). -If the variable has its -integer - -attribute set, then -value - -is evaluated as an arithmetic expression even if the -$((...)) - -expansion is not used (see -Arithmetic Expansion - -below). -Word splitting and pathname expansion are not performed. -Assignment statements may also appear as arguments to the -alias, - -declare, - -typeset, - -export, - -readonly, - -and -local - -builtin commands (declaration commands). -When in posix mode, these builtins may appear in a command after -one or more instances of the 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, the - -operator appends to or adds to -the variable's previous value. -This includes arguments to declaration commands such as -declare - -that accept assignment statements. -When - -is applied to a variable for which the -integer - -attribute has been set, -the variable's current value and value are each evaluated as -arithmetic expressions, -and the sum of the results is assigned as the variable's value. -The current value is usually an integer constant, but may be an expression. -When - -is applied to an array variable using compound assignment -(see -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, value is expanded and -appended to the variable's value. -

- -A variable can be assigned the nameref attribute using the --n option to the declare or local builtin commands -(see the descriptions of declare and local below) -to create a nameref, or a reference to another variable. -This allows variables to be manipulated indirectly. -Whenever the nameref variable is referenced, assigned to, unset, or has -its attributes modified (other than using or changing the nameref -attribute itself), the -operation is actually performed on the variable specified by the nameref -variable's value. -A nameref is commonly used within shell functions to refer to a variable -whose name is passed as an argument to the function. -For instance, if a variable name is passed to a shell function as its first -argument, running -

- -

- -declare -n ref=$1 - -
- -

- -inside the function creates a local nameref variable ref whose value -is the variable name passed as the first argument. -References and assignments to ref, and changes to its attributes, -are treated as references, assignments, and attribute modifications -to the variable whose name was passed as $1. -If the control variable in a for loop has the nameref attribute, -the list of words can be a list of shell variables, and a name reference -is established for each word in the list, in turn, when the loop is -executed. -Array variables cannot be given the nameref attribute. -However, nameref variables can reference array variables and subscripted -array variables. -Namerefs can be unset using the -n option to the unset builtin. -Otherwise, if unset is executed with the name of a nameref variable -as an argument, the variable referenced by the nameref variable is unset. -

- -When the shell starts, it reads its environment and creates a shell -variable from each environment variable that has a valid name, -as described below -(see -ENVIRONMENT). - - -  -

Positional Parameters

- -A -positional parameter - -is a parameter denoted by one or more -digits, other than the single digit 0. -Positional parameters are -assigned from the shell's arguments when it is invoked, -and may be reassigned using the -set - -builtin command. -Positional parameters may not be assigned to -with assignment statements. -The positional parameters are -temporarily replaced when a shell function is executed (see -FUNCTIONS - - -below). -

- -When a positional parameter consisting of more than a single -digit is expanded, it must be enclosed in braces (see -EXPANSION - - -below). -Without braces, a digit following $ can only refer to -one of the first nine positional parameters ($1-$9) or the -special parameter $0 (see the next section). -  -

Special Parameters

- -The shell treats several parameters specially. -These parameters may only be referenced; assignment to them is -not allowed. -Special parameters are denoted by one of the following characters. -
-
-
-* - -($*) Expands to the positional parameters, starting from one. -When the expansion is not within double quotes, each positional parameter -expands to a separate word. -In contexts where word expansions are performed, those words -are subject to further word splitting and pathname expansion. -When the expansion occurs within double quotes, it expands to a -single word with the value of each parameter separated by the first -character of the -IFS - - -variable. -That is, -$* - -is equivalent to -$1c$2c..., - -where -c - -is the first character of the value of the -IFS - - -variable. -If -IFS - - -is unset, the parameters are separated by spaces. -If -IFS - - -is null, the parameters are joined without intervening separators. -
@ - -
-($@) Expands to the positional parameters, starting from one. -In contexts where word splitting is performed, this expands each -positional parameter to a separate word; if not within double -quotes, these words are subject to word splitting. -In contexts where word splitting is not performed, -such as the value portion of an assignment statement, -this expands to a single word -with each positional parameter separated by a space. -When the expansion occurs within double quotes, -and word splitting is performed, -each parameter expands to a separate word. -That is, -$@ - -is equivalent to -$1 $2 ... - -If the double-quoted expansion occurs within a word, the expansion of -the first parameter is joined with the expansion of the -beginning part of the original word, -and the expansion of the last parameter is joined with the -expansion of the last part of the original word. -When there are no positional parameters, -$@ - -and -$@ - -expand to nothing (i.e., they are removed). -
# - -
-($#) Expands to the number of positional parameters in decimal. -
? - -
-($?) Expands to the exit status of the most recently executed command. -
- - -
-($-) Expands to the current option flags as specified upon invocation, -by the -set - -builtin command, or those set by the shell itself -(such as the --i - -option). -
$ - -
-($$) Expands to the process ID of the shell. -In a subshell, it expands to the process ID of the parent shell, -not the subshell. -
! - -
-($!)Expands to the process ID of the job most recently placed into the -background, whether executed as an asynchronous command or using -the bg builtin (see -JOB CONTROL - - -below). -
0 - -
-($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, -$0 - -is set to the name of that file. -If bash is started with the --c - -option, then -$0 - -is set to the first argument after the string to be -executed, if one is present. -Otherwise, it is set to the filename used to invoke -bash, - -as given by argument zero. - -
-  -

Shell Variables

- -The shell sets following variables: -

- - -

-
_ - -
-($_, an underscore) -This has a number of meanings depending on context. -At shell startup, _ is set to the pathname used to invoke the -shell or shell script being executed as passed in the environment -or argument list. -Subsequently, it expands to the last argument to the previous simple -command executed in the foreground, after expansion. -It is also set to the full pathname used to invoke each command executed -and placed in the environment exported to that command. -When checking mail, $_ expands to the name of the mail file -currently being checked. -
BASH - -
-Expands to the full filename used to invoke this instance of -bash. - -
BASHOPTS - -
-A colon-separated list of enabled shell options. Each word in -the list is a valid argument for the --s - -option to the -shopt - -builtin command (see -SHELL BUILTIN COMMANDS - - -below). -The options appearing in -BASHOPTS - - -are those reported as -on - -by shopt. -If this variable is in the environment when -bash - -starts up, the shell enables each option in the list before -reading any startup files. -If this variable is exported, child shells will enable each option -in the list. -This variable is read-only. -
BASHPID - -
-Expands to the process ID of the current bash process. -This differs from $$ under certain circumstances, such as subshells -that do not require bash to be re-initialized. -Assignments to -BASHPID - - -have no effect. -If -BASHPID - - -is unset, it loses its special properties, even if it is -subsequently reset. -
BASH_ALIASES - -
-An associative array variable whose members correspond to the internal -list of aliases as maintained by the alias builtin. -Elements added to this array appear in the alias list; however, -unsetting array elements currently does not remove aliases -from the alias list. -If -BASH_ALIASES - - -is unset, it loses its special properties, even if it is -subsequently reset. -
BASH_ARGC - -
-An array variable whose values are the number of parameters in each -frame of the current bash execution call stack. -The number of parameters to the current subroutine (shell function or -script executed with . or source) is at the top of the stack. -When a subroutine is executed, the number of parameters passed is pushed onto -BASH_ARGC. - - -The shell sets -BASH_ARGC - - -only when in extended debugging mode (see the description of the -extdebug - -option to the -shopt - -builtin below). -Setting extdebug after the shell has started to execute a script, -or referencing this variable when extdebug is not set, -may result in inconsistent values. -Assignments to -BASH_ARGC - - -have no effect, and it may not be unset. -
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 shell pushes the supplied parameters onto -BASH_ARGV. - - -The shell sets -BASH_ARGV - - -only when in extended debugging mode -(see the description of the -extdebug - -option to the -shopt - -builtin below). -Setting extdebug after the shell has started to execute a script, -or referencing this variable when extdebug is not set, -may result in inconsistent values. -Assignments to -BASH_ARGV - - -have no effect, and it may not be unset. -
BASH_ARGV0 - -
-When referenced, this variable expands to the name of the shell or shell -script (identical to -$0; - -see the description of special parameter 0 above). -Assigning a value to -BASH_ARGV0 - - -sets $0 to the same value. -If -BASH_ARGV0 - - -is unset, it loses its special properties, even if it is -subsequently reset. -
BASH_CMDS - -
-An associative array variable whose members correspond to the internal -hash table of commands as maintained by the hash builtin. -Adding elements to this array makes them appear in the hash table; however, -unsetting array elements currently does not remove command names -from the hash table. -If -BASH_CMDS - - -is unset, it loses its special properties, even if it is -subsequently reset. -
BASH_COMMAND - -
-Expands to the command currently being executed or about to be executed, -unless the shell is executing a command as the result of a trap, -in which case it is the command executing at the time of the trap. -If -BASH_COMMAND - - -is unset, it loses its special properties, even if it is -subsequently reset. -
BASH_EXECUTION_STRING - -
-The command argument to the -c invocation option. -
BASH_LINENO - -
-An array variable whose members are the line numbers in source files -where each corresponding member of -FUNCNAME - - -was invoked. -${BASH_LINENO[$i]} -is the line number in the source file -(${BASH_SOURCE[$i+1]}) -where -${FUNCNAME[$i]} -was called -(or ${BASH_LINENO[$i-1]} if referenced within another -shell function). -Use -LINENO - - -to obtain the current line number. -Assignments to -BASH_LINENO - - -have no effect, and it may not be unset. -
BASH_LOADABLES_PATH - -
-A colon-separated list of directories in which the -enable - -command -looks for -dynamically loadable builtins. -
BASH_MONOSECONDS - -
-Each time this variable is referenced, it expands to the value returned -by the system's monotonic clock, if one is available. -If there is no monotonic clock, this is equivalent to EPOCHSECONDS. -If -BASH_MONOSECONDS - - -is unset, it loses its special properties, even if it is -subsequently reset. -
BASH_REMATCH - -
-An array variable whose members are assigned by the =~ binary -operator to the [[ conditional command. -The element with index 0 is the portion of the string -matching the entire regular expression. -The element with index n is the portion of the -string matching the nth parenthesized subexpression. -
BASH_SOURCE - -
-An array variable whose members are the source filenames -where the corresponding shell function names in the -FUNCNAME - - -array variable are defined. -The shell function -${FUNCNAME[$i]} is defined in the file -${BASH_SOURCE[$i]} and called from -${BASH_SOURCE[$i+1]}. -Assignments to -BASH_SOURCE - - -have no effect, and it may not be unset. -
BASH_SUBSHELL - -
-Incremented by one within each subshell or subshell environment when -the shell begins executing in that environment. -The initial value is 0. -If -BASH_SUBSHELL - - -is unset, it loses its special properties, even if it is -subsequently reset. -
BASH_TRAPSIG - -
-Set to the signal number corresponding to the trap action being executed -during its execution. -See the description of trap under -SHELL BUILTIN COMMANDS - - -below for information about signal numbers and trap execution. -
BASH_VERSINFO - -
-A readonly array variable whose members hold version information for -this instance of -bash. - -The values assigned to the array members are as follows: -
-

- -

-
-
BASH_VERSINFO[0] - -
-The major version number (the release). -
BASH_VERSINFO[1] - -
-The minor version number (the version). -
BASH_VERSINFO[2] - -
-The patch level. -
BASH_VERSINFO[3] - -
-The build version. -
BASH_VERSINFO[4] - -
-The release status (e.g., beta). -
BASH_VERSINFO[5] - -
-The value of -MACHTYPE. - - -
- -
-
BASH_VERSION - -
-Expands to a string describing the version of this instance of -bash - -(e.g., 5.2.37(3)-release). -
COMP_CWORD - -
-An index into ${COMP_WORDS} of the word containing the current -cursor position. -This variable is available only in shell functions invoked by the -programmable completion facilities (see Programmable Completion -below). -
COMP_KEY - -
-The key (or final key of a key sequence) used to invoke the current -completion function. -This variable is available only in shell functions and external -commands invoked by the -programmable completion facilities (see Programmable Completion -below). -
COMP_LINE - -
-The current command line. -This variable is available only in shell functions and external -commands invoked by the -programmable completion facilities (see Programmable Completion -below). -
COMP_POINT - -
-The index of the current cursor position relative to the beginning of -the current command. -If the current cursor position is at the end of the current command, -the value of this variable is equal to ${#COMP_LINE}. -This variable is available only in shell functions and external -commands invoked by the -programmable completion facilities (see Programmable Completion -below). -
COMP_TYPE - -
-Set to an integer value corresponding to the type of attempted completion -that caused a completion function to be called: -TAB, for normal completion, -?, for listing completions after successive tabs, -!, for listing alternatives on partial word completion, -@, to list completions if the word is not unmodified, -or -%, for menu completion. -This variable is available only in shell functions and external -commands invoked by the -programmable completion facilities (see Programmable Completion -below). -
COMP_WORDBREAKS - -
-The set of characters that the readline library treats as word -separators when performing word completion. -If -COMP_WORDBREAKS - - -is unset, it loses its special properties, even if it is -subsequently reset. -
COMP_WORDS - -
-An array variable (see Arrays below) consisting of the individual -words in the current command line. -The line is split into words as readline would split it, using -COMP_WORDBREAKS - - -as described above. -This variable is available only in shell functions invoked by the -programmable completion facilities (see Programmable Completion -below). -
COPROC - -
-An array variable (see Arrays below) created to hold the file descriptors -for output from and input to an unnamed coprocess (see Coprocesses -above). -
DIRSTACK - -
-An array variable (see -Arrays - -below) containing the current contents of the directory stack. -Directories appear in the stack in the order they are displayed by the -dirs - -builtin. -Assigning to members of this array variable may be used to modify -directories already in the stack, but the -pushd - -and -popd - -builtins must be used to add and remove directories. -Assigning to this variable does not change the current directory. -If -DIRSTACK - - -is unset, it loses its special properties, even if it is -subsequently reset. -
EPOCHREALTIME - -
-Each time this parameter is referenced, it expands to the number of seconds -since the Unix Epoch (see -time(3)) - -as a floating-point value with micro-second granularity. -Assignments to -EPOCHREALTIME - - -are ignored. -If -EPOCHREALTIME - - -is unset, it loses its special properties, even if it is -subsequently reset. -
EPOCHSECONDS - -
-Each time this parameter is referenced, it expands to the number of seconds -since the Unix Epoch (see -time(3)). - -Assignments to -EPOCHSECONDS - - -are ignored. -If -EPOCHSECONDS - - -is unset, it loses its special properties, even if it is -subsequently reset. -
EUID - -
-Expands to the effective user ID of the current user, initialized at -shell startup. This variable is readonly. -
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 - -This variable exists only when a shell function is executing. -Assignments to -FUNCNAME - - -have no effect. -If -FUNCNAME - - -is unset, it loses its special properties, even if it is -subsequently reset. -
-This variable can be used with -BASH_LINENO - - -and -BASH_SOURCE. - - -Each element of -FUNCNAME - - -has corresponding elements in -BASH_LINENO - - -and -BASH_SOURCE - - -to describe the call stack. -For instance, -${FUNCNAME[$i]} -was called from the file -${BASH_SOURCE[$i+1]} -at line number -${BASH_LINENO[$i]}. -The caller builtin displays the current call stack using this -information. - -
GROUPS - -
-An array variable containing the list of groups of which the current -user is a member. -Assignments to -GROUPS - - -have no effect. -If -GROUPS - - -is unset, it loses its special properties, even if it is -subsequently reset. -
HISTCMD - -
-The history number, or index in the history list, of the current -command. -Assignments to -HISTCMD - - -have no effect. -If -HISTCMD - - -is unset, it loses its special properties, even if it is -subsequently reset. -
HOSTNAME - -
-Automatically set to the name of the current host. -
HOSTTYPE - -
-Automatically set to a string that uniquely -describes the type of machine on which -bash - -is executing. -The default is system-dependent. -
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 -LINENO - - -is unset, it loses its special properties, even if it is -subsequently reset. -
MACHTYPE - -
-Automatically set to a string that fully describes the system -type on which -bash - -is executing, in the standard GNU cpu-company-system format. -The default is system-dependent. -
MAPFILE - -
-An array variable (see Arrays below) created to hold the text -read by the mapfile builtin when no variable name is supplied. -
OLDPWD - -
-The previous working directory as set by the -cd - -command. -
OPTARG - -
-The value of the last option argument processed by the -getopts - -builtin command (see -SHELL BUILTIN COMMANDS - - -below). -
OPTIND - -
-The index of the next argument to be processed by the -getopts - -builtin command (see -SHELL BUILTIN COMMANDS - - -below). -
OSTYPE - -
-Automatically set to a string that -describes the operating system on which -bash - -is executing. -The default is system-dependent. -
PIPESTATUS - -
-An array variable (see -Arrays - -below) containing a list of exit status values from the commands -in the most-recently-executed foreground pipeline, which may -consist of only a simple command -(see -SHELL GRAMMAR - - -above). -Bash sets -PIPESTATUS - - -after executing multi-element pipelines, -timed and negated pipelines, -simple commands, -subshells created with the ( operator, -the -[[ - -and -(( - -compound commands, and -after error conditions that result in the -shell aborting command execution. -
PPID - -
-The process ID of the shell's parent. -This variable is readonly. -
PWD - -
-The current working directory as set by the -cd - -command. -
RANDOM - -
-Each time this parameter is referenced, it expands to a random integer -between 0 and 32767. -Assigning a value to -RANDOM - - -initializes (seeds) the sequence of random numbers. -Seeding the random number generator with the same constant value -produces the same sequence of values. -If -RANDOM - - -is unset, it loses its special properties, even if it is -subsequently reset. -
READLINE_ARGUMENT - -
-Any numeric argument given to a -readline - -command that was defined using - -(see -SHELL BUILTIN COMMANDS - - -below) -when it was invoked. -
READLINE_LINE - -
-The contents of the -readline - -line buffer, for use with - -(see -SHELL BUILTIN COMMANDS - - -below). -
READLINE_MARK - -
-The position of the mark (saved insertion point) in the -readline - -line buffer, for use with - -(see -SHELL BUILTIN COMMANDS - - -below). -The characters between the insertion point and the mark are often -called the region. -
READLINE_POINT - -
-The position of the insertion point in the -readline - -line buffer, for use with - -(see -SHELL BUILTIN COMMANDS - - -below). -
REPLY - -
-Set to the line of input read by the -read - -builtin command when no arguments are supplied. -
SECONDS -
-Each time this parameter is -referenced, it expands to the number of seconds since shell invocation. -If a value is assigned to -SECONDS, - - -the value returned upon subsequent -references is -the number of seconds since the assignment plus the value assigned. -The number of seconds at shell invocation and the current time are always -determined by querying the system clock at one-second resolution. -If -SECONDS - - -is unset, it loses its special properties, even if it is -subsequently reset. -
SHELLOPTS - -
-A colon-separated list of enabled shell options. -Each word in the list is a valid argument for the --o - -option to the -set - -builtin command (see -SHELL BUILTIN COMMANDS - - -below). -The options appearing in -SHELLOPTS - - -are those reported as -on - -by set -o. -If this variable is in the environment when -bash - -starts up, the shell enables each option in the list before -reading any startup files. -If this variable is exported, child shells will enable each option -in the list. -This variable is read-only. -
SHLVL - -
-Incremented by one each time an instance of -bash - -is started. -
SRANDOM - -
-Each time it is referenced, this variable expands to a 32-bit pseudo-random -number. -The random number generator is not linear on systems that -support - -/dev/urandom - -or -arc4random(3), - -so each returned number -has no relationship to the numbers preceding it. -The random number generator cannot be seeded, so assignments to this -variable have no effect. -If -SRANDOM - - -is unset, it loses its special properties, -even if it is subsequently reset. -
UID - -
-Expands to the user ID of the current user, initialized at shell startup. -This variable is readonly. - -
-

- -The shell uses the following variables. In some cases, -bash - -assigns a default value to a variable; these cases are noted -below. -

- - -

-
BASH_COMPAT - -
-The value is used to set the shell's compatibility level. -See -SHELL COMPATIBILITY MODE - - -below for a description of the various compatibility -levels and their effects. -The value may be a decimal number (e.g., 4.2) or an integer (e.g., 42) -corresponding to the desired compatibility level. -If -BASH_COMPAT - - -is unset or set to the empty string, the compatibility -level is set to the default for the current version. -If -BASH_COMPAT - - -is set to a value that is not one of the valid -compatibility levels, the shell prints an error message and sets the -compatibility level to the default for the current version. -A subset of the valid values correspond to the compatibility levels -described below under -SHELL COMPATIBILITY MODE. - - -For example, 4.2 and 42 are valid values that correspond -to the compat42 shopt option -and set the compatibility level to 42. -The current version is also a valid value. -
BASH_ENV - -
-If this parameter is set when bash is executing a shell script, -its expanded value is interpreted as a filename containing commands to -initialize the shell before it reads and executes commands from the -script. -The value of -BASH_ENV - - -is subjected to parameter expansion, command substitution, and arithmetic -expansion before being interpreted as a filename. -PATH - - -is not used to search for the resultant filename. -
BASH_XTRACEFD - -
-If set to an integer corresponding to a valid file descriptor, -bash writes the trace output generated when - -is enabled to that file descriptor, -instead of the standard error. -The file descriptor is closed when -BASH_XTRACEFD - - -is unset or assigned a new value. -Unsetting -BASH_XTRACEFD - - -or assigning it the empty string causes the -trace output to be sent to the standard error. -Note that setting -BASH_XTRACEFD - - -to 2 (the standard error file -descriptor) and then unsetting it will result in the standard error -being closed. -
CDPATH - -
-The search path for the -cd - -command. -This is a colon-separated list of directories where the shell looks for -directories specified as arguments to the -cd - -command. -A sample value is - -
CHILD_MAX - -
-Set the number of exited child status values for the shell to remember. -Bash will not allow this value to be decreased below a -POSIX --mandated minimum, -and there is a maximum value (currently 8192) that this may not exceed. -The minimum value is system-dependent. -
COLUMNS - -
-Used by the select compound command to determine the terminal width -when printing selection lists. -Automatically set if the -checkwinsize - -option is enabled or in an interactive shell upon receipt of a -SIGWINCH. - - -
COMPREPLY - -
-An array variable from which bash reads the possible completions -generated by a shell function invoked by the programmable completion -facility (see Programmable Completion below). -Each array element contains one possible completion. -
EMACS - -
-If bash finds this variable in the environment when the shell starts -with value - -it assumes that the shell is running in an Emacs shell buffer and disables -line editing. -
ENV - -
-Expanded and executed similarly to -BASH_ENV - - -(see -INVOCATION - - -above) when an interactive shell is invoked in posix mode. -
EXECIGNORE - -
-A colon-separated list of shell patterns (see Pattern Matching) -defining the set of filenames to be ignored by command search using -PATH. - - -Files whose full pathnames match one of these patterns are not considered -executable files for the purposes of completion and command execution -via -PATH - - -lookup. -This does not affect the behavior of the [, test, and [[ -commands. -Full pathnames in the command hash table are not subject to -EXECIGNORE. - - -Use this variable to ignore shared library files that have the executable -bit set, but are not executable files. -The pattern matching honors the setting of the extglob shell -option. -
FCEDIT - -
-The default editor for the -fc - -builtin command. -
FIGNORE - -
-A colon-separated list of suffixes to ignore when performing -filename completion (see -READLINE - - -below). -A filename whose suffix matches one of the entries in -FIGNORE - - -is excluded from the list of matched filenames. -A sample value is - -
FUNCNEST - -
-If set to a numeric value greater than 0, defines a maximum function -nesting level. -Function invocations that exceed this nesting level -cause the current command to abort. -
GLOBIGNORE - -
-A colon-separated list of patterns defining the set of file names to -be ignored by pathname expansion. -If a file name matched by a pathname expansion pattern also matches one -of the patterns in -GLOBIGNORE, - - -it is removed from the list of matches. -The pattern matching honors the setting of the extglob shell -option. -
GLOBSORT - -
- -Controls how the results of pathname expansion are sorted. -The value of this variable specifies the sort criteria and sort order for -the results of pathname expansion. -If this variable is unset or set to the null string, pathname expansion -uses the historical behavior of sorting by name, -in ascending lexicographic order as determined by the -LC_COLLATE - - -shell variable. -
-If set, a valid value begins with an optional +, which is ignored, -or -, which reverses the sort order from ascending to descending, -followed by a sort specifier. -The valid sort specifiers are -name, - -numeric, - -size, - -mtime, - -atime, - -ctime, - -and -blocks, - -which sort the files on name, -names in numeric rather than lexicographic order, -file size, modification time, access time, -inode change time, and number of blocks, respectively. -If any of the non-name keys compare as equal (e.g., if two files are -the same size), sorting uses the name as a secondary sort key. -
-For example, a value of -mtime sorts the results in descending -order by modification time (newest first). -
-The numeric specifier treats names consisting solely of digits as -numbers and sorts them using their numeric value -(so - -sorts before - -for example). -When using numeric, names containing non-digits sort after all -the all-digit names and are sorted by name using the traditional behavior. -
-A sort specifier of nosort disables sorting completely; -bash - -returns the results -in the order they are read from the file system, -ignoring any leading -. -
-If the sort specifier is missing, it defaults to name, -so a value of + is equivalent to the null string, -and a value of - sorts by name in descending order. -Any invalid value restores the historical sorting behavior. - -
HISTCONTROL - -
-A colon-separated list of values controlling how commands are saved on -the history list. -If the list of values includes -ignorespace, - -lines which begin with a -space - -character are not saved in the history list. -A value of -ignoredups - -causes lines matching the previous history entry not to be saved. -A value of -ignoreboth - -is shorthand for ignorespace and ignoredups. -A value of -erasedups - -causes all previous lines matching the current line to be removed from -the history list before that line is saved. -Any value not in the above list is ignored. -If -HISTCONTROL - - -is unset, or does not include a valid value, -bash saves all lines read by the shell parser on the history list, -subject to the value of -HISTIGNORE. - - -If the first line of a multi-line compound command was saved, -the second and subsequent lines are not tested, -and are added to the history regardless of the value of -HISTCONTROL. - - -If the first line was not saved, the second and subsequent lines of -the command are not saved either. -
HISTFILE - -
-The name of the file in which command history is saved (see -HISTORY - - -below). -Bash assigns a default value of - -~/.bash_history. - -If -HISTFILE - - -is unset or null, -the shell does not save the command history when it exits. -
HISTFILESIZE - -
-The maximum number of lines contained in the history file. -When this variable is assigned a value, the history file is truncated, -if necessary, to contain no more than -the number of history entries -that total no more than that number of lines -by removing the oldest entries. -If the history list contains multi-line entries, -the history file may contain more lines than this maximum -to avoid leaving partial history entries. +

PWD

 + + +

The current working directory as set by the cd +command.

+ + +

RANDOM

 + + +

Each time this parameter is referenced, it expands to a +random integer between 0 and 32767. Assigning a value to +RANDOM initializes (seeds) the +sequence of random numbers. Seeding the random number +generator with the same constant value produces the same +sequence of values. If RANDOM is +unset, it loses its special properties, even if it is +subsequently reset.

+ +

READLINE_ARGUMENT

+ +

Any numeric argument given to a +readline command that was defined using “bind +−x” (see SHELL BUILTIN +COMMANDS below) when it was invoked.

+ +

READLINE_LINE

+ +

The contents of the +readline line buffer, for use with “bind +−x” (see SHELL BUILTIN +COMMANDS below).

+ +

READLINE_MARK

+ +

The position of the mark (saved +insertion point) in the readline line buffer, for use +with “bind −x” (see SHELL +BUILTIN COMMANDS below). The characters between +the insertion point and the mark are often called the +region.

+ +

READLINE_POINT

+ +

The position of the insertion +point in the readline line buffer, for use with +“bind −x” (see SHELL BUILTIN +COMMANDS below).

+ + + + + + + +
+ + +

REPLY

 + + +

Set to the line of input read by the read builtin +command when no arguments are supplied.

+ +

SECONDS

+ +

Each time this parameter is +referenced, it expands to the number of seconds since shell +invocation. If a value is assigned to +SECONDS, the value +returned upon subsequent references is the number of seconds +since the assignment plus the value assigned. The number of +seconds at shell invocation and the current time are always +determined by querying the system clock at one-second +resolution. If SECONDS is unset, it +loses its special properties, even if it is subsequently +reset.

+ +

SHELLOPTS

+ +

A colon-separated list of +enabled shell options. Each word in the list is a valid +argument for the −o option to the set +builtin command (see SHELL BUILTIN +COMMANDS below). The options appearing in +SHELLOPTS are those reported as +on by set −o. If this variable is in the +environment when bash starts up, the shell enables +each option in the list before reading any startup files. If +this variable is exported, child shells will enable each +option in the list. This variable is read-only.

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

SHLVL

 + + +

Incremented by one each time an instance of bash +is started.

 +
+ +

SRANDOM

+ +

Each time it is referenced, +this variable expands to a 32-bit pseudo-random number. The +random number generator is not linear on systems that +support /dev/urandom or arc4random(3), so each +returned number has no relationship to the numbers preceding +it. The random number generator cannot be seeded, so +assignments to this variable have no effect. If +SRANDOM is unset, it loses its special +properties, even if it is subsequently reset.

+ + + + + + + +
+ + +

UID

 + + +

Expands to the user ID of the current user, initialized +at shell startup. This variable is readonly.

+ +

The shell uses +the following variables. In some cases, bash assigns +a default value to a variable; these cases are noted below. +
+BASH_COMPAT

+ +

The value is used to set the +shell’s compatibility level. See SHELL +COMPATIBILITY MODE below for a description of +the various compatibility levels and their effects. The +value may be a decimal number (e.g., 4.2) or an integer +(e.g., 42) corresponding to the desired compatibility level. +If BASH_COMPAT is unset or set to the +empty string, the compatibility level is set to the default +for the current version. If +BASH_COMPAT is set to a value that is +not one of the valid compatibility levels, the shell prints +an error message and sets the compatibility level to the +default for the current version. A subset of the valid +values correspond to the compatibility levels described +below under SHELL COMPATIBILITY +MODE. For example, 4.2 and 42 are +valid values that correspond to the compat42 shopt +option and set the compatibility level to 42. The current +version is also a valid value.

+ +

BASH_ENV

+ +

If this parameter is set when +bash is executing a shell script, its expanded value +is interpreted as a filename containing commands to +initialize the shell before it reads and executes commands +from the script. The value of BASH_ENV +is subjected to parameter expansion, command substitution, +and arithmetic expansion before being interpreted as a +filename. PATH is not used to search +for the resultant filename.

+ +

BASH_XTRACEFD

+ +

If set to an integer +corresponding to a valid file descriptor, bash writes +the trace output generated when “set −x” +is enabled to that file descriptor, instead of the standard +error. The file descriptor is closed when +BASH_XTRACEFD is unset or assigned a +new value. Unsetting BASH_XTRACEFD or +assigning it the empty string causes the trace output to be +sent to the standard error. Note that setting +BASH_XTRACEFD to 2 (the standard error +file descriptor) and then unsetting it will result in the +standard error being closed.

+ + + + + + + +
+ + +

CDPATH

 + + +

The search path for the cd command. This is a +colon-separated list of directories where the shell looks +for directories specified as arguments to the cd +command. A sample value is “.:~:/usr”.

+ +

CHILD_MAX

+ +

Set the number of exited child +status values for the shell to remember. Bash will +not allow this value to be decreased below a +POSIX -mandated minimum, and there is a +maximum value (currently 8192) that this may not exceed. The +minimum value is system-dependent.

+ +

COLUMNS

+ +

Used by the select +compound command to determine the terminal width when +printing selection lists. Automatically set if the +checkwinsize option is enabled or in an interactive +shell upon receipt of a +SIGWINCH.

+ +

COMPREPLY

+ +

An array variable from which +bash reads the possible completions generated by a +shell function invoked by the programmable completion +facility (see Programmable Completion below). Each +array element contains one possible completion.

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

EMACS

 + + +

If bash finds this variable in the environment +when the shell starts with value “t”, it assumes +that the shell is running in an Emacs shell buffer and +disables line editing.

+ + +

ENV

 + + +

Expanded and executed similarly to +BASH_ENV (see +INVOCATION above) when an interactive +shell is invoked in posix mode.

+ +

EXECIGNORE

+ +

A colon-separated list of shell +patterns (see Pattern Matching) defining the set of +filenames to be ignored by command search using +PATH. Files whose full +pathnames match one of these patterns are not considered +executable files for the purposes of completion and command +execution via PATH lookup. This does +not affect the behavior of the [, test, and +[[ commands. Full pathnames in the command hash table +are not subject to +EXECIGNORE. Use this +variable to ignore shared library files that have the +executable bit set, but are not executable files. The +pattern matching honors the setting of the extglob +shell option.

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

FCEDIT

 + + +

The default editor for the fc builtin +command.

 +
+ +

FIGNORE

+ +

A colon-separated list of +suffixes to ignore when performing filename completion (see +READLINE below). A filename whose +suffix matches one of the entries in +FIGNORE is excluded from the list of +matched filenames. A sample value is “.o:~”.

+ +

FUNCNEST

+ +

If set to a numeric value +greater than 0, defines a maximum function nesting level. +Function invocations that exceed this nesting level cause +the current command to abort.

+ +

GLOBIGNORE

+ +

A colon-separated list of +patterns defining the set of file names to be ignored by +pathname expansion. If a file name matched by a pathname +expansion pattern also matches one of the patterns in +GLOBIGNORE, it is +removed from the list of matches. The pattern matching +honors the setting of the extglob shell option.

+ +

GLOBSORT

+ +

Controls how the results of +pathname expansion are sorted. The value of this variable +specifies the sort criteria and sort order for the results +of pathname expansion. If this variable is unset or set to +the null string, pathname expansion uses the historical +behavior of sorting by name, in ascending lexicographic +order as determined by the LC_COLLATE +shell variable.

+ +

If set, a valid +value begins with an optional +, which is ignored, or +−, which reverses the sort order from ascending +to descending, followed by a sort specifier. The valid sort +specifiers are name, numeric, size, +mtime, atime, ctime, and blocks, +which sort the files on name, names in numeric rather than +lexicographic order, file size, modification time, access +time, inode change time, and number of blocks, respectively. +If any of the non-name keys compare as equal (e.g., if two +files are the same size), sorting uses the name as a +secondary sort key.

+ +

For example, a +value of −mtime sorts the results in descending +order by modification time (newest first).

+ +

The +numeric specifier treats names consisting solely of +digits as numbers and sorts them using their numeric value +(so “2” sorts before “10”, for +example). When using numeric, names containing +non-digits sort after all the all-digit names and are sorted +by name using the traditional behavior.

+ +

A sort +specifier of nosort disables sorting completely; +bash returns the results in the order they are read +from the file system, ignoring any leading +−.

+ +

If the sort +specifier is missing, it defaults to name, so a value +of + is equivalent to the null string, and a value of +- sorts by name in descending order. Any invalid +value restores the historical sorting behavior.

+ +

HISTCONTROL

+ +

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

+ +

HISTFILE

+ +

The name of the file in which +command history is saved (see HISTORY +below). Bash assigns a default value of +~/.bash_history. If HISTFILE is +unset or null, the shell does not save the command history +when it exits.

+ +

HISTFILESIZE

+ +

The maximum number of lines +contained in the history file. When this variable is +assigned a value, the history file is truncated, if +necessary, to contain no more than the number of history +entries that total no more than that number of lines by +removing the oldest entries. If the history list contains +multi-line entries, the history file may contain more lines +than this maximum to avoid leaving partial history entries. The history file is also truncated to this size after -writing it when a shell exits or by the -history - -builtin. -If the value is 0, the history file is truncated to zero size. -Non-numeric values and numeric values less than zero inhibit truncation. -The shell sets the default value to the value of -HISTSIZE - - -after reading any startup files. -

HISTIGNORE - -
-A colon-separated list of patterns used to decide which command lines -should be saved on the history list. -If a command line matches one of the patterns in the value of -HISTIGNORE, - - -it is not saved on the history list. -Each pattern is anchored at the +writing it when a shell exits or by the history +builtin. If the value is 0, the history file is truncated to +zero size. Non-numeric values and numeric values less than +zero inhibit truncation. The shell sets the default value to +the value of HISTSIZE after reading +any startup files.

+ +

HISTIGNORE

+ +

A colon-separated list of +patterns used to decide which command lines should be saved +on the history list. If a command line matches one of the +patterns in the value of +HISTIGNORE, it is not +saved on the history list. Each pattern is anchored at the beginning of the line and must match the complete line -(bash does not implicitly append a +(bash does not implicitly append a +“*”). Each pattern is tested against the +line after the checks specified by +HISTCONTROL are applied. In addition +to the normal shell pattern matching characters, +“&” matches the previous history +line. A backslash escapes the “&”; +the backslash is removed before attempting a match. If the +first line of a multi-line compound command was saved, the +second and subsequent lines are not tested, and are added to +the history regardless of the value of +HISTIGNORE. If the +first line was not saved, the second and subsequent lines of +the command are not saved either. The pattern matching +honors the setting of the extglob shell option. +
+HISTIGNORE subsumes some of the function of +HISTCONTROL. A pattern +of “&” is identical to +“ignoredups”, and a pattern of “[ +]*” is identical to “ignorespace”. +Combining these two patterns, separating them with a colon, +provides the functionality of “ignoreboth”.

+ +

HISTSIZE

+ +

The number of commands to +remember in the command history (see +HISTORY below). If the value is 0, +commands are not saved in the history list. Numeric values +less than zero result in every command being saved on the +history list (there is no limit). The shell sets the default +value to 500 after reading any startup files.

+ +

HISTTIMEFORMAT

+ +

If this variable is set and not +null, its value is used as a format string for +strftime(3) to print the time stamp associated with +each history entry displayed by the history builtin. +If this variable is set, the shell writes time stamps 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.

+ + + + + + + +
+ + +

HOME

 + + +

The home directory of the current user; the default +argument for the cd builtin command. The value of +this variable is also used when performing tilde +expansion.

+ +

HOSTFILE

+ +

Contains the name of a file in +the same format as /etc/hosts that should be read +when the shell needs to complete a hostname. The list of +possible hostname completions may be changed while the shell +is running; the next time hostname completion is attempted +after the value is changed, bash adds the contents of +the new file to the existing list. If +HOSTFILE is set, but has no value, or +does not name a readable file, bash attempts to read +/etc/hosts to obtain the list of possible hostname +completions. When HOSTFILE is unset, +bash clears the hostname list.

+ + + + + + + +
+ + +

IFS

 + + +

The Internal Field Separator that is used for +word splitting after expansion and to split lines into words +with the read builtin command. Word splitting is +described below under +EXPANSION. The default +value is +“<space><tab><newline>”.

-Each pattern is tested against the line -after the checks specified by -HISTCONTROL +

IGNOREEOF

- -are applied. -In addition to the normal shell pattern matching characters, +

Controls the action of an +interactive shell on receipt of an EOF +character as the sole input. If set, the value is the number +of consecutive EOF characters which +must be typed as the first characters on an input line +before bash exits. If the variable is set but does +not have a numeric value, or the value is null, the default +value is 10. If it is unset, EOF +signifies the end of input to the shell.

-matches the previous history line. -A backslash escapes the +

INPUTRC

-the backslash is removed before attempting a match. -If the first line of a multi-line compound command was saved, -the second and subsequent lines are not tested, -and are added to the history regardless of the value of -HISTIGNORE. +

The filename for the +readline startup file, overriding the default of +~/.inputrc (see READLINE +below).

- -If the first line was not saved, the second and subsequent lines of -the command are not saved either. -The pattern matching honors the setting of the -extglob +

INSIDE_EMACS

-shell option. -
-HISTIGNORE +

If this variable appears in the +environment when the shell starts, bash assumes that +it is running inside an Emacs shell buffer and may disable +line editing, depending on the value of +TERM.

- -subsumes some of the function of -HISTCONTROL. + + + + + + + + + + + +
- -A pattern of -is identical to +

LANG

 -and a pattern of -is identical to +

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

-Combining these two patterns, separating them with a colon, -provides the functionality of - -
HISTSIZE - -
-The number of commands to remember in the command history (see -HISTORY - - -below). -If the value is 0, commands are not saved in the history list. -Numeric values less than zero result in every command being saved -on the history list (there is no limit). -The shell sets the default value to 500 after reading any startup files. -
HISTTIMEFORMAT - -
-If this variable is set and not null, its value is used as a format string -for -strftime(3) - -to print the time stamp associated with each history -entry displayed by the history builtin. -If this variable is set, the shell writes time stamps 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. -
HOME - -
-The home directory of the current user; the default argument for the -cd builtin command. -The value of this variable is also used when performing tilde expansion. -
HOSTFILE - -
-Contains the name of a file in the same format as - -/etc/hosts - -that should be read when the shell needs to complete a -hostname. -The list of possible hostname completions may be changed while the -shell is running; -the next time hostname completion is attempted after the -value is changed, -bash - -adds the contents of the new file to the existing list. -If -HOSTFILE - - -is set, but has no value, or does not name a readable file, -bash attempts to read - -/etc/hosts - -to obtain the list of possible hostname completions. -When -HOSTFILE - - -is unset, bash clears the hostname list. -
IFS - -
-The -Internal Field Separator - -that is used -for word splitting after expansion and to -split lines into words with the -read - -builtin command. -Word splitting is described below under -EXPANSION. - - -The default value is - -
IGNOREEOF - -
-Controls the -action of an interactive shell on receipt of an -EOF - - -character as the sole input. -If set, the value is the number of consecutive -EOF - - -characters which must be -typed as the first characters on an input line before -bash - -exits. -If the variable is set but does not have a numeric value, -or the value is null, -the default value is 10. -If it is unset, -EOF - - -signifies the end of input to the shell. -
INPUTRC - -
-The filename for the -readline - -startup file, overriding the default of - -~/.inputrc - -(see -READLINE - - -below). -
INSIDE_EMACS - -
-If this variable appears in the environment when the shell starts, -bash assumes that it is running inside an Emacs shell buffer -and may disable line editing, depending on the value of -TERM. - - -
LANG - -
-Used to determine the locale category for any category not specifically -selected with a variable starting with LC_. -
LC_ALL - -
-This variable overrides the value of -LANG - - -and any other -LC_ variable specifying a locale category. -
LC_COLLATE - -
-This variable determines the collation order used when sorting the -results of pathname expansion, and determines the behavior of range -expressions, equivalence classes, and collating sequences within -pathname expansion and pattern matching. -
LC_CTYPE - -
-This variable determines the interpretation of characters and the -behavior of character classes within pathname expansion and pattern -matching. -
LC_MESSAGES - -
-This variable determines the locale used to translate double-quoted -strings preceded by a $. -
LC_NUMERIC - -
-This variable determines the locale category used for number formatting. -
LC_TIME - -
-This variable determines the locale category used for data and time -formatting. -
LINES - -
-Used by the select compound command to determine the column length -for printing selection lists. -Automatically set if the -checkwinsize - -option is enabled or in an interactive shell upon receipt of a -SIGWINCH. - - -
MAIL - -
-If the value is set to a file or directory name and the -MAILPATH - - -variable is not set, -bash - -informs the user of the arrival of mail in the specified file or -Maildir-format directory. -
MAILCHECK - -
-Specifies how -often (in seconds) -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. -
MAILPATH - -
-A colon-separated list of filenames to be checked for mail. -The message to be printed when mail arrives in a particular file -may be specified by separating the filename from the message with a - -When used in the text of the message, $_ expands to the name of -the current mailfile. -For example: -
-

- - -MAILPATH='/var/mail/bfox?" -You have mail" -:~/shell-mail?" -$_ has mail!" -' - -

- -Bash - -can be configured to supply -a default value for this variable (there is no value by default), -but the location of the user -mail files that it uses is system dependent (e.g., /var/mail/$USER). -

- -
OPTERR - -
-If set to the value 1, -bash - -displays error messages generated by the -getopts - -builtin command (see -SHELL BUILTIN COMMANDS - - -below). -OPTERR - - -is initialized to 1 each time the shell is invoked or a shell -script is executed. -
PATH - -
-The search path for commands. -It is a colon-separated list of directories in which -the shell looks for commands (see -COMMAND EXECUTION - - -below). -A zero-length (null) directory name in the value of -PATH - - -indicates the current directory. -A null directory name may appear as two adjacent colons, or as an initial -or trailing colon. -The default path is system-dependent, -and is set by the administrator who installs -bash. -A common value is -
-
+

LC_ALL

 -/usr/local/bin:/usr/local/sbin: -
+

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

-/usr/bin:/usr/sbin:/bin:/sbin +

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.

-
+

LC_CTYPE

-
POSIXLY_CORRECT +

This variable determines the +interpretation of characters and the behavior of character +classes within pathname expansion and pattern matching.

-
-If this variable is in the environment when bash starts, the shell -enters posix mode before reading the startup files, as if the ---posix +

LC_MESSAGES

-invocation option had been supplied. -If it is set while the shell is -running, bash enables posix mode, as if the command +

This variable determines the +locale used to translate double-quoted strings preceded by a +$.

-had been executed. -When the shell enters posix mode, it sets this variable if it was -not already set. -
PROMPT_COMMAND +

LC_NUMERIC

-
-If this variable is set, and is an array, -the value of each set element is executed as a command -prior to issuing each primary prompt. -If this is set but not an array variable, -its value is used as a command to execute instead. -
PROMPT_DIRTRIM +

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

-
-If set to a number greater than zero, the value is used as the number of -trailing directory components to retain when expanding the \w and -\W prompt string escapes (see -PROMPTING +

LC_TIME

- -below). -Characters removed are replaced with an ellipsis. -
PS0 +

This variable determines the +locale category used for data and time formatting.

-
-The value of this parameter is expanded (see -PROMPTING + + + + + + + + + + + +
- -below) and displayed by interactive shells after reading a command -and before the command is executed. -
PS1 -
-The value of this parameter is expanded (see -PROMPTING +

LINES

 - -below) and used as the primary prompt string. -The default value is -
PS2 +

Used by the select compound command to determine +the column length for printing selection lists. +Automatically set if the checkwinsize option is +enabled or in an interactive shell upon receipt of a +SIGWINCH.

-
-The value of this parameter is expanded as with -PS1 - -and used as the secondary prompt string. -The default is +

MAIL

 -
PS3 -
-The value of this parameter is used as the prompt for the -select +

If the value is set to a file or directory name and the +MAILPATH variable is not set, +bash informs the user of the arrival of mail in the +specified file or Maildir-format directory.

-command (see -SHELL GRAMMAR +

MAILCHECK

- -above). -
PS4 +

Specifies how often (in +seconds) 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.

-
-The value of this parameter is expanded as with -PS1 +

MAILPATH

- -and the value is printed before each command -bash +

A colon-separated list of +filenames to be checked for mail. The message to be printed +when mail arrives in a particular file may be specified by +separating the filename from the message with a +“?”. When used in the text of the message, +$_ expands to the name of the current mailfile. For +example:
+MAILPATH='/var/mail/bfox?"You have +mail":~/shell−mail?"$_ has mail!"' +
+Bash can be configured to supply a default value for +this variable (there is no value by default), but the +location of the user mail files that it uses is system +dependent (e.g., /var/mail/$USER).

-displays during an execution trace. -The first character of the expanded value of -PS4 - - -is replicated multiple times, as necessary, to indicate multiple -levels of indirection. -The default is - -
SHELL - -
-This variable expands to the full pathname to the shell. -If it is not set when the shell starts, -bash - -assigns to it the full pathname of the current user's login shell. -
TIMEFORMAT - -
-The value of this parameter is used as a format string specifying -how the timing information for pipelines prefixed with the -time - -reserved word should be displayed. -The % character introduces an escape sequence that is -expanded to a time value or other information. -The escape sequences and their meanings are as follows; the -brackets denote optional portions. -
-

- -

- -
-
%% - -
-A literal %. -
%[p][l]R - -
-The elapsed time in seconds. -
%[p][l]U - -
-The number of CPU seconds spent in user mode. -
%[p][l]S - -
-The number of CPU seconds spent in system mode. -
%P - -
-The CPU percentage, computed as (%U + %S) / %R. - -
- -
-
-The optional p is a digit specifying the precision, -the number of fractional digits after a decimal point. -A value of 0 causes no decimal point or fraction to be output. -time prints at most six digits after the decimal point; -values of p greater than 6 are changed to 6. -If p is not specified, -time prints three digits after the decimal point. -
-The optional l specifies a longer format, including -minutes, of the form MMmSS.FFs. -The value of p determines whether or not the fraction is -included. -
-If this variable is not set, bash acts as if it had the -value $'\nreal\t%3lR\nuser\t%3lU\nsys\t%3lS'. -If the value is null, bash does not display any timing information. -A trailing newline is added when the format string is displayed. - -
TMOUT - -
-If set to a value greater than zero, -the read builtin uses the value as its -default timeout. -The select command terminates if input does not arrive -after -TMOUT - - -seconds when input is coming from a terminal. -In an interactive shell, the value is interpreted as the -number of seconds to wait for a line of input after issuing the -primary prompt. -Bash - -terminates after waiting for that number of seconds if a -complete line of input does not arrive. -
TMPDIR - -
-If set, bash uses its value as the name of a directory in which -bash creates temporary files for the shell's use. -
auto_resume - -
-This variable controls how the shell interacts with the user and -job control. -If this variable is set, simple commands -consisting of only a single word, -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 or containing -the word, this selects the most recently accessed job. -The -name - -of a stopped job, in this context, is the command line used to -start it, as displayed by jobs. -If set to the value -exact, - -the word must match the name of a stopped job exactly; -if set to -substring, - -the word needs to match a substring of the name of a stopped job. -The -substring - -value provides functionality analogous to the -%? - -job identifier (see -JOB CONTROL - - -below). -If set to any other value (e.g., -prefix), - -the word must be a prefix of a stopped job's name; -this provides functionality analogous to the %string job identifier. -
histchars - -
-The two or three characters which control history expansion, -quick substitution, and tokenization -(see -HISTORY EXPANSION - - -below). -The first character is the history expansion character, -the character which begins a history expansion, normally - -The second character is the quick substitution character, normally - -When it appears as the first character on the line, -history substitution repeats the previous command, -replacing one string with another. -The optional third character is the -history comment -character, normally - -which indicates -that the remainder of the line is a comment -when it appears as the first character of a word. -The history comment character disables history substitution -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. - -
-  -

Arrays

- -Bash - -provides one-dimensional indexed and associative array variables. -Any variable may be used as an indexed array; the -declare - -builtin explicitly declares 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 arithmetic expressions -that must expand to an integer -(see -ARITHMETIC EVALUATION - - -below) -and are zero-based; -associative arrays are referenced using arbitrary strings. -Unless otherwise noted, indexed array indices must be non-negative integers. -

- -The shell performs -parameter and variable expansion, arithmetic expansion, -command substitution, and quote removal -on indexed array subscripts. -Since this -can potentially result in empty strings, -subscript indexing treats -those as expressions that evaluate to 0. -

- -The shell performs -tilde expansion, -parameter and variable expansion, arithmetic expansion, -command substitution, and quote removal -on associative array subscripts. -Empty strings cannot be used as associative array keys. -

+ + + + + + + + + + + +
-Bash automatically creates an indexed array -if any variable is assigned to using the syntax -
-name[subscript]=value -. -
-The -subscript +

OPTERR

 -is treated as an arithmetic expression that must evaluate to a number -greater than or equal to zero. -To explicitly declare an indexed array, use -
-declare -a name -
+

If set to the value 1, bash displays error +messages generated by the getopts builtin command +(see SHELL BUILTIN COMMANDS below). +OPTERR is initialized to 1 each time +the shell is invoked or a shell script is executed.

-(see -SHELL BUILTIN COMMANDS - -below). -
-declare -a name[subscript] -
+

PATH

 -is also accepted; the subscript is ignored. -

-Associative arrays are created using -

-declare -A name +

The search path for commands. It is a colon-separated +list of directories in which the shell looks for commands +(see COMMAND EXECUTION below). A +zero-length (null) directory name in the value of +PATH indicates the current directory. +A null directory name may appear as two adjacent colons, or +as an initial or trailing colon. The default path is +system-dependent, and is set by the administrator who +installs bash. A common value is

- -. -

+

/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin

-Attributes may be specified for an array variable using the -declare +

POSIXLY_CORRECT

-and -readonly +

If this variable is in the +environment when bash starts, the shell enters posix +mode before reading the startup files, as if the +−−posix invocation option had been +supplied. If it is set while the shell is running, +bash enables posix mode, as if the command “set +−o posix” had been executed. When the shell +enters posix mode, it sets this variable if it was not +already set.

-builtins. -Each attribute applies to all members of an array. -

+

PROMPT_COMMAND

-Arrays are assigned using compound assignments of the form -name=(value1 ... valuen), where each -value may be of the form [subscript]=string. -Indexed array assignments do not require anything but string. -Each value in the list is expanded using the shell expansions -described below under -EXPANSION, - - -but values that are valid variable assignments -including the brackets and subscript do not undergo -brace expansion and word splitting, as with individual -variable assignments. -

- -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. -

- -When assigning to an associative array, the words in a compound assignment -may be either assignment statements, for which the subscript is required, -or a list of words that is interpreted as a sequence of alternating keys -and values: -name=( key1 value1 key2 value2 ...). -These are treated identically to -name=( [key1]=value1 [key2]=value2 -...). -The first word in the list determines how the remaining words -are interpreted; all assignments in a list must be of the same type. -When using key/value pairs, the keys may not be missing or empty; -a final missing value is treated like the empty string. -

- -This syntax is also accepted by the -declare - -builtin. -Individual array elements may be assigned to using the -name[subscript]=value syntax introduced above. -

- -When assigning to an indexed array, if -name - -is subscripted by a negative number, that number is -interpreted as relative to one greater than the maximum index of -name, so negative indices count back from the end of the -array, and an index of -1 references the last element. -

- -The - -operator appends to an array variable when assigning -using the compound assignment syntax; see -PARAMETERS - - -above. -

- -An array element is referenced using -${name[subscript]}. -The braces are required to avoid conflicts with pathname expansion. -If subscript is @ or *, the word expands to -all members of name, -unless noted in the description of a builtin or word expansion. -These subscripts differ only when the -word appears within double quotes. -If the word is double-quoted, ${name[*]} expands to a single -word with the value of each array member separated by the first -character of the -IFS - - -special variable, and ${name[@]} expands each element of -name to a separate word. -When there are no array members, ${name[@]} expands to nothing. -If the double-quoted expansion occurs within a word, the expansion of -the first parameter is joined with the beginning part of the -expansion of the original word, -and the expansion of the last parameter is joined with the last -part of the -expansion of the original word. -This is analogous to the expansion -of the special parameters * and @ (see -Special Parameters - -above). -

- -${#name[subscript]} expands to the length of -${name[subscript]}. -If subscript is * or @, -the expansion is the number of elements in the array. -

- -If the -subscript - -used to reference an element of an indexed array -evaluates to a number less than zero, it is -interpreted as relative to one greater than the maximum index of the array, -so negative indices count back from the end of the -array, and an index of -1 references the last element. -

- -Referencing an array variable without a subscript is equivalent to -referencing the array with a subscript of 0. -Any reference to a variable using a valid subscript is valid; -bash - -creates an array if necessary. -

- -An array variable is considered set if a subscript has been assigned a -value. -The null string is a valid value. -

- -It is possible to obtain the keys (indices) of an array as well as the values. -${!name[@]} and ${!name[*]} -expand to the indices assigned in array variable name. -The treatment when in double quotes is similar to the expansion of the -special parameters @ and * within double quotes. -

- -The -unset - -builtin is used to destroy arrays. -unset name[subscript] -unsets the array element at index subscript, -for both indexed and associative arrays. -Negative subscripts to indexed arrays are interpreted as described above. -Unsetting the last element of an array variable does not unset the variable. -unset name, where name is an array, -removes the entire array. -unset name[subscript] -behaves differently depending on -whether name is an indexed or associative array -when subscript is * or @. -If name is an associative array, this unsets the element with -subscript * or @. -If name is an indexed array, unset removes all of the elements but -does not remove the array itself. -

- -When using a variable name with a subscript as an argument to a command, -such as with unset, without using the word expansion syntax -described above, -(e.g., unset a[4]), -the argument is subject to pathname expansion. -Quote the argument if pathname expansion is not desired -(e.g., unset 'a[4]'). -

- -The -declare, - -local, - -and -readonly - -builtins each accept a --a - -option to specify an indexed array and a --A - -option to specify an associative array. -If both options are supplied, --A - -takes precedence. -The -read - -builtin accepts a --a - -option to assign a list of words read from the standard input -to an array. -The -set - -and -declare - -builtins display array values in a way that allows them to be -reused as assignments. -Other builtins accept array name arguments as well -(e.g., mapfile); see the descriptions -of individual builtins below for details. -The shell provides a number of builtin array variables. -  -

EXPANSION

- -Expansion is performed on the command line after it has been split into -words. The shell performs these expansions: -brace expansion, - -tilde expansion, - -parameter and variable expansion, - -command substitution, - -arithmetic expansion, - -word splitting, - -pathname expansion, - -and -quote removal. - -

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

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

- -Quote removal is always performed last. -It removes quote characters present in the original word, -not ones resulting from one of the other expansions, -unless they have been quoted themselves. -

+

If this variable is set, and is +an array, the value of each set element is executed as a +command prior to issuing each primary prompt. If this is set +but not an array variable, its value is used as a command to +execute instead.

-Only brace expansion, word splitting, and pathname expansion -can increase 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 -$@ +

PROMPT_DIRTRIM

-and -${name[@]} , +

If set to a number greater than +zero, the value is used as the number of trailing directory +components to retain when expanding the \w and +\W prompt string escapes (see +PROMPTING below). Characters removed +are replaced with an ellipsis.

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
-and, in most cases, $* and ${name[*]} -as explained above (see -PARAMETERS). +

PS0

 - -  -

Brace Expansion

-Brace expansion +

The value of this parameter is expanded (see +PROMPTING below) and displayed by +interactive shells after reading a command and before the +command is executed.

-is a mechanism to generate arbitrary strings -sharing a common prefix and suffix, either of which can be empty. -This mechanism is similar to -pathname expansion, but the filenames generated -need not exist. -Patterns to be brace expanded are formed from an optional -preamble, -followed by either a series of comma-separated strings or -a sequence expression between a pair of braces, -followed by an optional -postscript. +

PS1

 -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; -brace expansion preserves left to right order. -For example, a{d,c,b}e expands into +

The value of this parameter is expanded (see +PROMPTING below) and used as the +primary prompt string. The default value is +“\s−\v\$ ”.

-

-A sequence expression takes the form -x..y[..incr], -where x and y are either integers or single letters, -and incr, an optional increment, is an integer. -When integers are supplied, the expression expands to each number between -x and y, inclusive. -If either x or y begins with a zero, -each generated term will contain the same number of digits, -zero-padding where necessary. -When letters are supplied, the expression expands to each character -lexicographically between x and y, inclusive, -using the C locale. -Note that both x and y must be of the same type -(integer or letter). -When the increment is supplied, it is used as the difference between -each term. -The default increment is 1 or -1 as appropriate. -

+

PS2

 -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. -

+

The value of this parameter is expanded as with +PS1 and used as the secondary prompt +string. The default is “> ”.

-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 +

PS3

 -or -Q , -may be quoted with a backslash to prevent its -being considered part of a brace expression. -To avoid conflicts with parameter expansion, the string -is not considered eligible for brace expansion, -and inhibits brace expansion until the closing +

The value of this parameter is used as the prompt for +the select command (see SHELL +GRAMMAR above).

-

-This construct is typically used as shorthand when the common -prefix of the strings to be generated is longer than in the -above example: -

+

PS4

 -
-mkdir /usr/local/src/bash/{old,new,dist,bugs} +

The value of this parameter is expanded as with +PS1 and the value is printed before +each command bash displays during an execution trace. +The first character of the expanded value of +PS4 is replicated multiple times, as +necessary, to indicate multiple levels of indirection. The +default is “+ ”.

+ - +

SHELL

 -or -
-chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}} +

This variable expands to the full pathname to the shell. +If it is not set when the shell starts, bash assigns +to it the full pathname of the current user’s login +shell.

- +

TIMEFORMAT

-

+

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

-Brace expansion introduces a slight incompatibility with -historical versions of -sh. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
-sh -does not treat opening or closing braces specially when they -appear as part of a word, and preserves them in the output. -Bash +

%%

 -removes braces from words as a consequence of brace expansion. -For example, a word entered to -sh -as +

A literal %.

 +
-appears identically in the output. -Bash -outputs that word as +

%[p][l]R

 -after brace expansion. -Start -bash -with the -+B +

The elapsed time in seconds.

 +
-option or disable brace expansion with the -+B -option to the -set +

%[p][l]U

 -command (see -SHELL BUILTIN COMMANDS - -below) for strict sh compatibility. -  -

Tilde Expansion

+

The number of CPU seconds spent in user mode.

 +
+ + +

%[p][l]S

 + + +

The number of CPU seconds spent in system mode.

 +
+ + +

%P

 + + +

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

 +
+ +

The optional +p is a digit specifying the precision, the +number of fractional digits after a decimal point. A value +of 0 causes no decimal point or fraction to be output. +time prints at most six digits after the decimal +point; values of p greater than 6 are changed to 6. +If p is not specified, time prints three +digits after the decimal point.

+ +

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

+ +

If this +variable is not set, bash acts as if it had the value +$'\nreal\t%3lR\nuser\t%3lU\nsys\t%3lS'. If the value +is null, bash does not display any timing +information. A trailing newline is added when the format +string is displayed.

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

TMOUT

 + + +

If set to a value greater than +zero, the read builtin uses the value as its default +timeout. The select command terminates if input does +not arrive after TMOUT seconds when +input is coming from a terminal. In an interactive shell, +the value is interpreted as the number of seconds to wait +for a line of input after issuing the primary prompt. +Bash terminates after waiting for that number of +seconds if a complete line of input does not arrive.

+ + +

TMPDIR

 + + +

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

+ +

auto_resume

+ +

This variable controls how the +shell interacts with the user and job control. If this +variable is set, simple commands consisting of only a single +word, 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 or +containing the word, this selects the most recently accessed +job. The name of a stopped job, in this context, is +the command line used to start it, as displayed by +jobs. If set to the value exact, the word must +match the name of a stopped job exactly; if set to +substring, the word needs to match a substring of the +name of a stopped job. The substring value provides +functionality analogous to the %? job identifier (see +JOB CONTROL below). If set to any +other value (e.g., prefix), the word must be a prefix +of a stopped job’s name; this provides functionality +analogous to the %string job identifier.

+ +

histchars

+ +

The two or three characters +which control history expansion, quick substitution, and +tokenization (see HISTORY EXPANSION +below). The first character is the history expansion +character, the character which begins a history expansion, +normally “!”. The second character is the +quick substitution character, normally +“^”. When it appears as the first +character on the line, history substitution repeats the +previous command, replacing one string with another. The +optional third character is the history comment +character, normally “#”, which indicates +that the remainder of the line is a comment when it appears +as the first character of a word. The history comment +character disables history substitution 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.

+ +

Arrays + +

+ + +

Bash +provides one-dimensional indexed and associative array +variables. Any variable may be used as an indexed array; the +declare builtin explicitly declares 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 arithmetic +expressions that must expand to an integer (see +ARITHMETIC EVALUATION below) and are +zero-based; associative arrays are referenced using +arbitrary strings. Unless otherwise noted, indexed array +indices must be non-negative integers.

+ +

The shell +performs parameter and variable expansion, arithmetic +expansion, command substitution, and quote removal on +indexed array subscripts. Since this can potentially result +in empty strings, subscript indexing treats those as +expressions that evaluate to 0.

+ +

The shell +performs tilde expansion, parameter and variable expansion, +arithmetic expansion, command substitution, and quote +removal on associative array subscripts. Empty strings +cannot be used as associative array keys.

+ +

Bash +automatically creates an indexed array if any variable is +assigned to using the syntax

+ + +

name[subscript]=value +.

+ +

The subscript is treated +as an arithmetic expression that must evaluate to a number +greater than or equal to zero. To explicitly declare an +indexed array, use

+ +

declare +−a name

+ +

(see SHELL BUILTIN +COMMANDS below).

+ +

declare −a +name[subscript]

+ +

is also accepted; the +subscript is ignored.

+ +

Associative +arrays are created using

+ +

declare +−A name

+ +

.

+ +

Attributes may +be specified for an array variable using the declare +and readonly builtins. Each attribute applies to all +members of an array.

+ +

Arrays are +assigned using compound assignments of the form +name=(value1 ... valuen), +where each value may be of the form +[subscript]=string. Indexed array assignments +do not require anything but string. Each value +in the list is expanded using the shell expansions described +below under EXPANSION, +but values that are valid variable assignments +including the brackets and subscript do not undergo brace +expansion and word splitting, as with individual variable +assignments.

+ +

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.

+ +

When assigning +to an associative array, the words in a compound assignment +may be either assignment statements, for which the subscript +is required, or a list of words that is interpreted as a +sequence of alternating keys and values: +name=( key1 value1 key2 value2 +...). These are treated identically to +name=( [key1]=value1 +[key2]=value2 ...). The first word in +the list determines how the remaining words are interpreted; +all assignments in a list must be of the same type. When +using key/value pairs, the keys may not be missing or empty; +a final missing value is treated like the empty string.

+ +

This syntax is +also accepted by the declare builtin. Individual +array elements may be assigned to using the +name[subscript]=value syntax introduced +above.

+ +

When assigning +to an indexed array, if name is subscripted by a +negative number, that number is interpreted as relative to +one greater than the maximum index of name, so +negative indices count back from the end of the array, and +an index of −1 references the last element.

+ +

The +“+=” operator appends to an array variable when +assigning using the compound assignment syntax; see +PARAMETERS above.

+ +

An array element +is referenced using ${name[subscript]}. The +braces are required to avoid conflicts with pathname +expansion. If subscript is @ or *, the +word expands to all members of name, unless noted in +the description of a builtin or word expansion. These +subscripts differ only when the word appears within double +quotes. If the word is double-quoted, ${name[*]} +expands to a single word with the value of each array member +separated by the first character of the +IFS special variable, and +${name[@]} expands each element of name to a +separate word. When there are no array members, +${name[@]} expands to nothing. If the double-quoted +expansion occurs within a word, the expansion of the first +parameter is joined with the beginning part of the expansion +of the original word, and the expansion of the last +parameter is joined with the last part of the expansion of +the original word. This is analogous to the expansion of the +special parameters * and @ (see Special +Parameters above).

+ + +

${#name[subscript]} +expands to the length of ${name[subscript]}. +If subscript is * or @, the expansion +is the number of elements in the array.

+ +

If the +subscript used to reference an element of an indexed +array evaluates to a number less than zero, it is +interpreted as relative to one greater than the maximum +index of the array, so negative indices count back from the +end of the array, and an index of −1 references the +last element.

+ +

Referencing an +array variable without a subscript is equivalent to +referencing the array with a subscript of 0. Any reference +to a variable using a valid subscript is valid; bash +creates an array if necessary.

+ +

An array +variable is considered set if a subscript has been assigned +a value. The null string is a valid value.

+ +

It is possible +to obtain the keys (indices) of an array as well as the +values. ${!name[@]} and +${!name[*]} expand to the indices +assigned in array variable name. The treatment when +in double quotes is similar to the expansion of the special +parameters @ and * within double quotes.

+ +

The unset +builtin is used to destroy arrays. unset +name[subscript] unsets the array element at +index subscript, for both indexed and associative +arrays. Negative subscripts to indexed arrays are +interpreted as described above. Unsetting the last element +of an array variable does not unset the variable. +unset name, where name is an array, +removes the entire array. unset +name[subscript] behaves differently depending +on whether name is an indexed or associative array +when subscript is * or @. If +name is an associative array, this unsets the element +with subscript * or @. If name is an +indexed array, unset removes all of the elements but does +not remove the array itself.

+ +

When using a +variable name with a subscript as an argument to a command, +such as with unset, without using the word expansion +syntax described above, (e.g., unset a[4]), the argument is +subject to pathname expansion. Quote the argument if +pathname expansion is not desired (e.g., unset 'a[4]').

+ +

The +declare, local, and readonly builtins +each accept a −a option to specify an indexed +array and a −A option to specify an associative +array. If both options are supplied, −A takes +precedence. The read builtin accepts a +−a option to assign a list of words read from +the standard input to an array. The set and +declare builtins display array values in a way that +allows them to be reused as assignments. Other builtins +accept array name arguments as well (e.g., mapfile); +see the descriptions of individual builtins below for +details. The shell provides a number of builtin array +variables.

+ +

EXPANSION + +

+ + +

Expansion is +performed on the command line after it has been split into +words. The shell performs these expansions: brace +expansion, tilde expansion, parameter and +variable expansion, command substitution, +arithmetic expansion, word splitting, +pathname expansion, and quote removal.

+ +

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

+ +

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

+ +

Quote +removal is always performed last. It removes quote +characters present in the original word, not ones resulting +from one of the other expansions, unless they have been +quoted themselves.

+ +

Only brace +expansion, word splitting, and pathname expansion can +increase 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 +"$@" and +"${name[@]}", and, in most +cases, $* and ${name[*]} as +explained above (see +PARAMETERS).

+ +

Brace Expansion + +

+ + +

Brace +expansion is a mechanism to generate arbitrary strings +sharing a common prefix and suffix, either of which can be +empty. This mechanism is similar to pathname +expansion, but the filenames generated need not exist. +Patterns to be brace expanded are formed from an optional +preamble, followed by either a series of +comma-separated strings or a sequence expression between a +pair of braces, followed by an optional postscript. +The preamble is prefixed to each string contained within the +braces, and the postscript is then appended to each +resulting string, expanding left to right.

+ +

Brace expansions +may be nested. The results of each expanded string are not +sorted; brace expansion preserves left to right order. For +example, a{d,c,b}e expands into “ade ace +abe”.

+ +

A sequence +expression takes the form +x..y[..incr], +where x and y are either integers or single +letters, and incr, an optional increment, is an +integer. When integers are supplied, the expression expands +to each number between x and y, inclusive. If +either x or y begins with a zero, each +generated term will contain the same number of digits, +zero-padding where necessary. When letters are supplied, the +expression expands to each character lexicographically +between x and y, inclusive, using the C +locale. Note that both x and y must be of the +same type (integer or letter). 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.

+ +

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 Q , may be quoted with a backslash to +prevent its being considered part of a brace expression. To +avoid conflicts with parameter expansion, the string +“${” is not considered eligible for brace +expansion, and inhibits brace expansion until the closing +“}”.

+ +

This construct +is typically used as shorthand when the common prefix of the +strings to be generated is longer than in the above +example:

+ +

mkdir +/usr/local/src/bash/{old,new,dist,bugs}

+ +

or

+ +

chown root +/usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}}

+ +

Brace expansion +introduces a slight incompatibility with historical versions +of sh. sh does not treat opening or closing +braces specially when they appear as part of a word, and +preserves them in the output. Bash removes braces +from words as a consequence of brace expansion. For example, +a word entered to sh as “file{1,2}” +appears identically in the output. Bash outputs that +word as “file1 file2” after brace expansion. +Start bash with the +B option or disable brace +expansion with the +B option to the set +command (see SHELL BUILTIN COMMANDS +below) for strict sh compatibility.

+ +

Tilde Expansion + +

+ + +

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

+ +

If the +tilde-prefix is a “~+”, the value of the shell +variable PWD replaces the +tilde-prefix. If the tilde-prefix is a +“~−”, the shell substitutes the value of +the shell variable +OLDPWD, if it is set. +If the characters following the tilde in the tilde-prefix +consist of a number N, optionally prefixed by a +“+” or a “−”, the tilde-prefix +is replaced with the corresponding element from the +directory stack, as it would be displayed by the dirs +builtin invoked with the characters following the tilde in +the tilde-prefix as an argument. If the characters following +the tilde in the tilde-prefix consist of a number without a +leading “+” or “−”, tilde +expansion assumes “+”.

+ +

The results of +tilde expansion are treated as if they were quoted, so the +replacement is not subject to word splitting and pathname +expansion.

+ +

If the login +name is invalid, or the tilde expansion fails, the +tilde-prefix is unchanged.

+ +

Bash +checks each variable assignment for unquoted tilde-prefixes +immediately following a : or the first =, and +performs tilde expansion in these cases. Consequently, one +may use filenames with tildes in assignments to +PATH, MAILPATH, +and CDPATH, and the +shell assigns the expanded value.

+ +

Bash also +performs tilde expansion on words satisfying the conditions +of variable assignments (as described above under +PARAMETERS) when they +appear as arguments to simple commands. Bash does not +do this, except for the declaration commands listed +above, when in posix mode.

+ +

Parameter Expansion + +

+ + +

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

+ +

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

+ +

The basic form +of parameter expansion is

+ + +

${parameter}

+ +

which +substitutes the value of parameter. The braces are +required when parameter is a positional parameter +with more than one digit, or when parameter is +followed by a character which is not to be interpreted as +part of its name. The parameter is a shell parameter +as described above PARAMETERS) or an array reference +(Arrays).

+ +

If the first +character of parameter is an exclamation point +(!), and parameter is not a nameref, it +introduces a level of indirection. Bash uses the +value formed by expanding the rest of parameter as +the new parameter; this new parameter is then +expanded and that value is used in the rest of the +expansion, rather than the expansion of the original +parameter. This is known as indirect +expansion. The value is subject to tilde expansion, +parameter expansion, command substitution, and arithmetic +expansion. If parameter is a nameref, this expands to +the name of the parameter referenced by parameter +instead of performing the complete indirect expansion, for +compatibility. The exceptions to this are the expansions of +${!prefix*} and +${!name[@]} described below. The +exclamation point must immediately follow the left brace in +order to introduce indirection.

+ +

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

+ +

When not +performing substring expansion, using the forms documented +below (e.g., :-), bash tests for a parameter +that is unset or null. Omitting the colon tests only for a +parameter that is unset.
+${parameter:−word}

+ +

Use Default Values. If +parameter is unset or null, the expansion of +word is substituted. Otherwise, the value of +parameter is substituted.

+ + +

${parameter:=word}

+ +

Assign Default Values. +If parameter is unset or null, the expansion of +word is assigned to parameter, and the +expansion is the final value of parameter. Positional +parameters and special parameters may not be assigned in +this way.

+ + +

${parameter:?word}

+ +

Display Error if Null or +Unset. If parameter is null or unset, the shell +writes the expansion of word (or a message to that +effect if word is not present) to the standard error +and, if it is not interactive, exits with a non-zero status. +An interactive shell does not exit, but does not execute the +command associated with the expansion. Otherwise, the value +of parameter is substituted.

+ + +

${parameter:+word}

+ +

Use Alternate Value. If +parameter is null or unset, nothing is substituted, +otherwise the expansion of word is substituted. The +value of parameter is not used.

+ + +

${parameter:offset} +
+ +${parameter:offset:length}

+ +

Substring Expansion. +Expands to up to length characters of the value of +parameter starting at the character specified by +offset. If parameter is @ or *, +an indexed array subscripted by @ or *, or an +associative array name, the results differ as described +below. If :length is omitted (the first form +above), this expands to the substring of the value of +parameter starting at the character specified by +offset and extending to the end of the value. If +offset is omitted, it is treated as 0. If +length is omitted, but the colon after offset +is present, it is treated as 0. length and +offset are arithmetic expressions (see +ARITHMETIC EVALUATION below).

+ +

If +offset evaluates to a number less than zero, the +value is used as an offset in characters from the end of the +value of parameter. If length evaluates to a +number less than zero, it is interpreted as an offset in +characters from the end of the value of parameter +rather than a number of characters, and the expansion is the +characters between offset and that result. Note that +a negative offset must be separated from the colon by at +least one space to avoid being confused with the :- +expansion.

+ +

If +parameter is @ or *, the result is +length positional parameters beginning at +offset. A negative offset is taken relative to +one greater than the greatest positional parameter, so an +offset of −1 evaluates to the last positional +parameter (or 0 if there are no positional parameters). It +is an expansion error if length evaluates to a number +less than zero.

+ +

If +parameter is an indexed array name subscripted by @ +or *, the result is the length members of the array +beginning with ${parameter[offset]}. A +negative offset is taken relative to one greater than +the maximum index of the specified array. It is an expansion +error if length evaluates to a number less than +zero.

+ +

Substring +expansion applied to an associative array produces undefined +results.

+ +

Substring +indexing is zero-based unless the positional parameters are +used, in which case the indexing starts at 1 by default. If +offset is 0, and the positional parameters are used, +$0 is prefixed to the list.

+ + +

${!prefix*} +
+${!prefix@}

+ +

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

+ + +

${!name[@]} +
+${!name[*]}

+ +

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

+ +

${#parameter}

+ +

Parameter length. +Substitutes the length in characters of the expanded value +of parameter. If parameter is * or +@, the value substituted is the number of positional +parameters. If parameter is an array name subscripted +by * or @, the value substituted is the number +of elements in the array. If parameter is an indexed +array name subscripted by a negative number, that number is +interpreted as relative to one greater than the maximum +index of parameter, so negative indices count back +from the end of the array, and an index of −1 +references the last element.

+ + +

${parameter#word} +
+${parameter##word}

+ +

Remove matching prefix +pattern. The word is expanded to produce a +pattern just as in pathname expansion, and matched against +the expanded value of parameter using the rules +described under Pattern Matching below. If the +pattern matches the beginning of the value of +parameter, then the result of the expansion is the +expanded value of parameter with the shortest +matching pattern (the “#” case) or the longest +matching pattern (the “##” case) deleted. If +parameter is @ or *, the pattern +removal operation is applied to each positional parameter in +turn, and the expansion is the resultant list. If +parameter is an array variable subscripted with +@ or *, the pattern removal operation is +applied to each member of the array in turn, and the +expansion is the resultant list.

+ + +

${parameter%word} +
+${parameter%%word}

+ +

Remove matching suffix +pattern. The word is expanded to produce a +pattern just as in pathname expansion, and matched against +the expanded value of parameter using the rules +described under Pattern Matching below. If the +pattern matches a trailing portion of the expanded value of +parameter, then the result of the expansion is the +expanded value of parameter with the shortest +matching pattern (the “%” case) or the longest +matching pattern (the “%%” case) deleted. If +parameter is @ or *, the pattern +removal operation is applied to each positional parameter in +turn, and the expansion is the resultant list. If +parameter is an array variable subscripted with +@ or *, the pattern removal operation is +applied to each member of the array in turn, and the +expansion is the resultant list.

+ + +

${parameter/pattern/string} +
+ +${parameter//pattern/string} +
+ +${parameter/#pattern/string} +
+ +${parameter/%pattern/string}

+ +

Pattern substitution. +The pattern is expanded to produce a pattern and +matched against the expanded value of parameter as +described under Pattern Matching below. The longest +match of pattern in the expanded value is replaced +with string. string undergoes tilde expansion, +parameter and variable expansion, arithmetic expansion, +command and process substitution, and quote removal.

+ +

In the first +form above, only the first match is replaced. If there are +two slashes separating parameter and pattern +(the second form above), all matches of pattern are +replaced with string. If pattern is preceded +by # (the third form above), it must match at the +beginning of the expanded value of parameter. If +pattern is preceded by % (the fourth form +above), it must match at the end of the expanded value of +parameter.

+ +

If the +expansion of string is null, matches of +pattern are deleted and the / following +pattern may be omitted.

+ +

If the +patsub_replacement shell option is enabled using +shopt, any unquoted instances of & in +string are replaced with the matching portion of +pattern.

+ +

Quoting any +part of string inhibits replacement in the expansion +of the quoted portion, including replacement strings stored +in shell variables. Backslash escapes & in +string; the backslash is removed in order to permit a +literal & in the replacement string. Backslash +can also be used to escape a backslash; \\ results in +a literal backslash in the replacement. Users should take +care if string is double-quoted to avoid unwanted +interactions between the backslash and double-quoting, since +backslash has special meaning within double quotes. Pattern +substitution performs the check for unquoted & +after expanding string; shell programmers should +quote any occurrences of & they want to be taken +literally in the replacement and ensure any instances of +& they want to be replaced are unquoted.

+ +

Like the +pattern removal operators, double quotes surrounding the +replacement string quote the expanded characters, while +double quotes enclosing the entire parameter substitution do +not, since the expansion is performed in a context that +doesn’t take any enclosing double quotes into +account.

+ +

If the +nocasematch shell option is enabled, the match is +performed without regard to the case of alphabetic +characters.

+ +

If +parameter is @ or *, the substitution +operation is applied to each positional parameter in turn, +and the expansion is the resultant list. If parameter +is an array variable subscripted with @ or *, +the substitution operation is applied to each member of the +array in turn, and the expansion is the resultant list.

+ + +

${parameter^pattern} +
+${parameter^^pattern}
+${parameter,pattern}
+${parameter,,pattern}

+ +

Case modification. This +expansion modifies the case of alphabetic characters in +parameter. First, the pattern is expanded to +produce a pattern as described below under Pattern +Matching. Bash then +examines characters in the expanded value of +parameter against pattern as described below. +If a character matches the pattern, its case is converted. +The pattern should not attempt to match more than one +character.

+ +

Using +“^” converts lowercase letters matching +pattern to uppercase; “,” converts +matching uppercase letters to lowercase. The ^ and +, variants examine the first character in the +expanded value and convert its case if it matches +pattern; the ^^ and ,, variants examine +all characters in the expanded value and convert each one +that matches pattern. If pattern is omitted, +it is treated like a ?, which matches every +character.

+ +

If +parameter is @ or *, the case +modification operation is applied to each positional +parameter in turn, and the expansion is the resultant list. +If parameter is an array variable subscripted with +@ or *, the case modification operation is +applied to each member of the array in turn, and the +expansion is the resultant list.

+ -If a word begins with an unquoted tilde character ( +

${parameter@operator}

-all of -the characters preceding the first unquoted slash (or all characters, -if there is no unquoted slash) are considered a tilde-prefix. -If none of the characters in the tilde-prefix are quoted, the -characters in the tilde-prefix following the tilde are treated as a -possible login name. -If this login name is the null string, the tilde is replaced with the -value of the shell parameter -HOME. +

Parameter +transformation. The expansion is either a transformation +of the value of parameter or information about +parameter itself, depending on the value of +operator. Each operator is a single +letter:

- -If -HOME + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
- -is unset, the tilde expands to -the home directory of the user executing the shell instead. -Otherwise, the tilde-prefix is replaced with the home directory -associated with the specified login name. -

-If the tilde-prefix is a +

U

 -the value of the shell variable -PWD - -replaces the tilde-prefix. -If the tilde-prefix is a +

The expansion is a string that is the value of +parameter with lowercase alphabetic characters +converted to uppercase.

-the shell substitutes the value of the shell variable -OLDPWD, - -if it is set. -If the characters following the tilde in the tilde-prefix consist -of a number N, optionally prefixed -by a +

u

 -or a -the tilde-prefix is replaced with the corresponding -element from the directory stack, as it would be displayed by the -dirs +

The expansion is a string that is the value of +parameter with the first character converted to +uppercase, if it is alphabetic.

-builtin invoked with the characters following the tilde in the -tilde-prefix as an argument. -If the characters following the tilde in the tilde-prefix consist of a -number without a leading -or +

L

 -tilde expansion assumes -

+

The expansion is a string that is the value of +parameter with uppercase alphabetic characters +converted to lowercase.

-The results of tilde expansion are treated as if they were quoted, so -the replacement is not subject to word splitting and pathname expansion. -

-If the login name is invalid, or the tilde expansion fails, the -tilde-prefix is unchanged. -

+

Q

 -Bash checks each variable assignment -for unquoted tilde-prefixes immediately -following a -: -or the first -=, +

The expansion is a string that is the value of +parameter quoted in a format that can be reused as +input.

-and performs tilde expansion in these cases. -Consequently, one may use filenames with tildes in assignments to -PATH, - -MAILPATH, +

E

 - -and -CDPATH, - -and the shell assigns the expanded value. -

+

The expansion is a string that is the value of +parameter with backslash escape sequences expanded as +with the $'...' quoting mechanism.

-Bash also performs tilde expansion on words satisfying the conditions -of variable assignments (as described above under -PARAMETERS) - - -when they appear as arguments to simple commands. -Bash does not do this, -except for the declaration commands listed above, -when in posix mode. -  -

Parameter Expansion

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

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

- -The basic form of parameter expansion is -

- -${parameter} -

- -which substitutes the value of parameter. -The braces are required -when -parameter - -is a positional parameter with more than one digit, -or when -parameter - -is followed by a character which is not to be -interpreted as part of its name. -The parameter is a shell parameter as described above -PARAMETERS) or an array reference (Arrays). - -

- -If the first character of parameter is an exclamation point (!), -and parameter is not a nameref, -it introduces a level of indirection. -Bash uses the value formed by expanding the rest of -parameter as the new parameter; -this new parameter is then expanded and that value is used -in the rest of the expansion, rather -than the expansion of the original parameter. -This is known as indirect expansion. -The value is subject to tilde expansion, -parameter expansion, command substitution, and arithmetic expansion. -If parameter is a nameref, this expands to the name of the -parameter referenced by parameter instead of performing the -complete indirect expansion, for compatibility. -The exceptions to this are the expansions of ${!prefix*} and -${!name[@]} described below. -The exclamation point must immediately follow the left brace in order to -introduce indirection. -

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

- -When not performing substring expansion, using the forms documented below -(e.g., :-), -bash tests for a parameter that is unset or null. -Omitting the colon tests only for a parameter that is unset. -

- -

-
${parameter:-word}
-Use Default Values. If -parameter - -is unset or null, the expansion of -word - -is substituted. -Otherwise, the value of -parameter - -is substituted. -
${parameter:=word}
-Assign Default Values. -If -parameter - -is unset or null, the expansion of -word - -is assigned to -parameter, - -and the expansion is the final value of -parameter. - -Positional parameters and special parameters may -not be assigned in this way. -
${parameter:?word}
-Display Error if Null or Unset. -If -parameter - -is null or unset, the shell writes -the expansion of word (or a message to that effect -if -word - -is not present) to the standard error and, if it -is not interactive, exits with a non-zero status. -An interactive shell does not exit, but does not execute the command -associated with the expansion. -Otherwise, the value of parameter is substituted. -
${parameter:+word}
-Use Alternate Value. -If -parameter - -is null or unset, nothing is substituted, otherwise the expansion of -word - -is substituted. -The value of parameter is not used. -
-
-${parameter:offset} -
-
-${parameter:offset:length} -Substring Expansion. -Expands to up to length characters of the value of parameter -starting at the character specified by offset. -If parameter is @ or *, an indexed array subscripted by -@ or *, or an associative array name, the results differ as -described below. -If :length is omitted (the first form above), this -expands to the substring of the value of -parameter starting at the character specified by offset -and extending to the end of the value. -If offset is omitted, -it is treated as 0. -If length is omitted, -but the colon after offset is present, -it is treated as 0. -length and offset are arithmetic expressions (see -ARITHMETIC EVALUATION - - -below). -
-If offset evaluates to a number less than zero, the value -is used as an offset in characters -from the end of the value of parameter. -If length evaluates to a number less than zero, -it is interpreted as an offset in characters -from the end of the value of parameter rather than -a number of characters, and the expansion is the characters between -offset and that result. -Note that a negative offset must be separated from the colon by at least -one space to avoid being confused with the :- expansion. -
-If parameter is @ or *, the result is length -positional parameters beginning at offset. -A negative offset is taken relative to one greater than the greatest -positional parameter, so an offset of -1 evaluates to the last positional -parameter (or 0 if there are no positional parameters). -It is an expansion error if length evaluates to a number less than -zero. -
-If parameter is an indexed array name subscripted by @ or *, -the result is the length -members of the array beginning with ${parameter[offset]}. -A negative offset is taken relative to one greater than the maximum -index of the specified array. -It is an expansion error if length evaluates to a number less than -zero. -
-Substring expansion applied to an associative array produces undefined -results. -
-Substring indexing is zero-based unless the positional parameters -are used, in which case the indexing starts at 1 by default. -If offset is 0, and the positional parameters are used, $0 is -prefixed to the list. -
-
-${!prefix*} -
${!prefix@}
- -Names matching prefix. -Expands to the names of variables whose names begin with prefix, -separated by the first character of the -IFS - - -special variable. -When @ is used and the expansion appears within double quotes, each -variable name expands to a separate word. -
-
-${!name[@]} -
${!name[*]}
- -List of array keys. -If name is an array variable, expands to the list of array indices -(keys) assigned in name. -If name is not an array, expands to 0 if name is set and null -otherwise. -When @ is used and the expansion appears within double quotes, each -key expands to a separate word. -
${#parameter}
-Parameter length. -Substitutes the length in characters of the expanded value of parameter. -If -parameter - -is -* - -or -@, - -the value substituted is the number of positional parameters. -If -parameter - -is an array name subscripted by -* - -or -@, - -the value substituted is the number of elements in the array. -If -parameter - -is an indexed array name subscripted by a negative number, that number is -interpreted as relative to one greater than the maximum index of -parameter, so negative indices count back from the end of the -array, and an index of -1 references the last element. -
-
-${parameter#word} -
${parameter##word}
- -Remove matching prefix pattern. -The -word - -is expanded to produce a pattern just as in pathname -expansion, and matched against the expanded value of -parameter - -using the rules described under -Pattern Matching - -below. -If the pattern matches the beginning of -the value of -parameter, - -then the result of the expansion is the expanded value of -parameter - -with the shortest matching pattern (the - -case) or the longest matching pattern (the - -case) deleted. -If -parameter - -is -@ - -or -*, - -the pattern removal operation is applied to each positional -parameter in turn, and the expansion is the resultant list. -If -parameter -is an array variable subscripted with -@ +

P

 -or -*, -the pattern removal operation is applied to each member of the -array in turn, and the expansion is the resultant list. -
-
-${parameter%word} -
${parameter%%word}
+

The expansion is a string that is the result of +expanding the value of parameter as if it were a +prompt string (see PROMPTING below).

-Remove matching suffix pattern. -The word is expanded to produce a pattern just as in -pathname expansion, and matched against the expanded value of -parameter -using the rules described under -Pattern Matching +

A

 -below. -If the pattern matches a trailing portion of the expanded value of -parameter, -then the result of the expansion is the expanded value of -parameter +

The expansion is a string in the form of an assignment +statement or declare command that, if evaluated, +recreates parameter with its attributes and +value.

-with the shortest matching pattern (the -case) or the longest matching pattern (the +

K

 -case) deleted. -If -parameter -is -@ +

Produces a possibly-quoted version of the value of +parameter, except that it prints the values of +indexed and associative arrays as a sequence of quoted +key-value pairs (see Arrays above). The keys and +values are quoted in a format that can be reused as +input.

-or -*, -the pattern removal operation is applied to each positional -parameter in turn, and the expansion is the resultant list. -If -parameter - -is an array variable subscripted with -@ - -or -*, - -the pattern removal operation is applied to each member of the -array in turn, and the expansion is the resultant list. -
-
-${parameter/pattern/string} -
${parameter//pattern/string}
-
${parameter/#pattern/string}
-
${parameter/%pattern/string}
- -Pattern substitution. -The pattern is expanded to produce a pattern -and matched against the expanded value of parameter -as described under -Pattern Matching - -below. -The longest match of pattern -in the expanded value is replaced with string. -string undergoes tilde expansion, parameter and variable expansion, -arithmetic expansion, command and process substitution, and quote removal. -
-In the first form above, only the first match is replaced. -If there are two slashes separating parameter and pattern -(the second form above), all matches of pattern are -replaced with string. -If pattern is preceded by # (the third form above), -it must match at the beginning of the expanded value of parameter. -If pattern is preceded by % (the fourth form above), -it must match at the end of the expanded value of parameter. -
-If the expansion of string is null, -matches of pattern are deleted -and the / following pattern may be omitted. -
-If the patsub_replacement shell option is enabled using shopt, -any unquoted instances of & in string are replaced with the -matching portion of pattern. -
-Quoting any part of string inhibits replacement in the -expansion of the quoted portion, including replacement strings stored -in shell variables. -Backslash escapes & in string; the backslash is removed -in order to permit a literal & in the replacement string. -Backslash can also be used to escape a backslash; \\ results in -a literal backslash in the replacement. -Users should take care if string is double-quoted to avoid -unwanted interactions between the backslash and double-quoting, since -backslash has special meaning within double quotes. -Pattern substitution performs the check for unquoted & after -expanding string; -shell programmers should quote any occurrences of & -they want to be taken literally in the replacement -and ensure any instances of & they want to be replaced are unquoted. -
-Like the pattern removal operators, double quotes surrounding the -replacement string quote the expanded characters, while double quotes -enclosing the entire parameter substitution do not, since -the expansion is performed in a -context that doesn't take any enclosing double quotes into account. -
-If the -nocasematch - -shell option is enabled, the match is performed without regard to the case -of alphabetic characters. -
-If -parameter - -is -@ - -or -*, - -the substitution operation is applied to each positional -parameter in turn, and the expansion is the resultant list. -If -parameter +

a

 -is an array variable subscripted with -@ -or -*, +

The expansion is a string consisting of flag values +representing parameter’s attributes.

-the substitution operation is applied to each member of the -array in turn, and the expansion is the resultant list. -
-
-${parameter^pattern} -
${parameter^^pattern}
-
${parameter,pattern}
-
${parameter,,pattern}
- -Case modification. -This expansion modifies the case of alphabetic characters in parameter. -First, the pattern is expanded to produce a pattern -as described below under -Pattern Matching. - - -Bash - -then examines characters in the expanded value of parameter -against pattern as described below. -If a character matches the pattern, its case is converted. -The pattern should not attempt to match more than one character. -
-Using - -converts lowercase letters matching pattern to uppercase; - -converts matching uppercase letters to lowercase. -The -^ and , variants -examine the first character in the expanded value -and convert its case if it matches pattern; -the -^^ and ,, variants -examine all characters in the expanded value -and convert each one that matches pattern. -If pattern is omitted, it is treated like a ?, which matches -every character. -
-If -parameter - -is -@ - -or -*, - -the case modification operation is applied to each positional -parameter in turn, and the expansion is the resultant list. -If -parameter - -is an array variable subscripted with -@ - -or -*, - -the case modification operation is applied to each member of the -array in turn, and the expansion is the resultant list. -
-
-${parameter@operator} -Parameter transformation. -The expansion is either a transformation of the value of parameter -or information about parameter itself, depending on the value of -operator. Each operator is a single letter: - -

- -

-
-
U - -
-The expansion is a string that is the value of parameter with lowercase -alphabetic characters converted to uppercase. -
u - -
-The expansion is a string that is the value of parameter with the first -character converted to uppercase, if it is alphabetic. -
L - -
-The expansion is a string that is the value of parameter with uppercase -alphabetic characters converted to lowercase. -
Q - -
-The expansion is a string that is the value of parameter quoted in a -format that can be reused as input. -
E - -
-The expansion is a string that is the value of parameter with backslash -escape sequences expanded as with the $'...' -quoting mechanism. -
P - -
-The expansion is a string that is the result of expanding the value of -parameter as if it were a prompt string (see PROMPTING below). -
A - -
-The expansion is a string in the form of -an assignment statement or declare command that, if -evaluated, recreates parameter with its attributes and value. -
K - -
-Produces a possibly-quoted version of the value of parameter, -except that it prints the values of -indexed and associative arrays as a sequence of quoted key-value pairs -(see Arrays above). -The keys and values are quoted in a format that can be reused as input. -
a - -
-The expansion is a string consisting of flag values representing -parameter's attributes. -
k - -
-Like the K transformation, but expands the keys and values of -indexed and associative arrays to separate words after word splitting. - -
-

- -If -parameter - -is -@ - -or -*, - -the operation is applied to each positional -parameter in turn, and the expansion is the resultant list. -If -parameter - -is an array variable subscripted with -@ - -or -*, - -the operation is applied to each member of the -array in turn, and the expansion is the resultant list. -

- -The result of the expansion is subject to word splitting and pathname -expansion as described below. -

- -  -

Command Substitution

- -Command substitution allows the output of a command to replace -the command itself. -There are two standard forms: -
-

- -$(command) -

- -or (deprecated) -
-`command`. -
- -

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

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

- -There is an alternate form of command substitution: -

-

- -${c command;} -

- -

- -which executes command in the current execution environment -and captures its output, again with trailing newlines removed. -

- -The character c following the open brace must be a space, tab, -newline, or |, and the close brace must be in a position -where a reserved word may appear (i.e., preceded by a command terminator -such as semicolon). -Bash allows the close brace to be joined to the remaining characters in -the word without being followed by a shell metacharacter as a reserved -word would usually require. -

- -Any side effects of command take effect immediately -in the current execution environment and persist in the current -environment after the command completes (e.g., the exit builtin -exits the shell). -

- -This type of command substitution superficially resembles executing an -unnamed shell function: local variables are created as when a shell -function is executing, and the return builtin forces -command to complete; -however, the rest of the execution environment, -including the positional parameters, is shared with the caller. -

- -If the first character following the open brace -is a |, the construct expands to the -value of the REPLY shell variable after command executes, -without removing any trailing newlines, -and the standard output of command remains the same as in the -calling shell. -Bash creates REPLY as an initially-unset local variable when -command executes, and restores REPLY to the value it had -before the command substitution after command completes, -as with any local variable. -

- -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, bash does not perform -word splitting and pathname expansion on the results. -  -

Arithmetic Expansion

- -Arithmetic expansion evaluates an arithmetic expression -and substitutes the result. -The format for arithmetic expansion is: -
-

- -$((expression)) -

- -

- -The -expression - -undergoes the same expansions -as if it were within double quotes, -but unescaped double quote characters -in expression are not treated -specially and are removed. -All tokens in the expression undergo parameter and variable expansion, -command substitution, and quote removal. -The result is treated as the arithmetic expression to be evaluated. -Since the way Bash handles double quotes -can potentially result in empty strings, -arithmetic expansion treats -those as expressions that evaluate to 0. -Arithmetic expansions may be nested. -

- -The evaluation is performed according to the rules listed below under -ARITHMETIC EVALUATION. - - -If -expression - -is invalid, -bash - -prints a message to standard error indicating failure, -does not perform the substitution, -and does not execute the command associated with the expansion. -  -

Process Substitution

- -Process substitution allows a process's input or output to be -referred to using a filename. -It takes the form of -<(list) -or ->(list). -The process list is run asynchronously, and its input or output -appears as a filename. -This filename is -passed as an argument to the current command as the result of the -expansion. -

- -If the ->(list) form is used, writing to -the file provides input for list. -If the -<(list) form is used, reading the file -obtains the output of list. -No space may appear between the < or > -and the left parenthesis, otherwise the construct would be interpreted -as a redirection. -

- -Process substitution is supported on systems that support named -pipes (FIFOs) or the /dev/fd method of naming open files. -

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

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. - -Words that were not expanded are not split. -

- -The shell treats each character of -IFS - - -as a delimiter, -and splits the results of the other expansions into words -using these characters as field terminators. -

-An IFS whitespace character is whitespace as defined above -(see Definitions) that appears in the value of -IFS. +

k

 - -Space, tab, and newline are always considered IFS whitespace, even -if they don't appear in the locale's space category. -

-If -IFS +

Like the K transformation, but expands the keys and +values of indexed and associative arrays to separate words +after word splitting.

- -is unset, field splitting acts as if its value were -<space><tab><newline>, +

If +parameter is @ or *, the operation is +applied to each positional parameter in turn, and the +expansion is the resultant list. If parameter is an +array variable subscripted with @ or *, the +operation is applied to each member of the array in turn, +and the expansion is the resultant list.

-and treats these characters as IFS whitespace. -If the value of -IFS +

The result of +the expansion is subject to word splitting and pathname +expansion as described below.

- -is null, no word splitting occurs, -but implicit null arguments (see below) are still removed. -

+

Command Substitution + +

-Word splitting begins by removing sequences of IFS whitespace characters -from the beginning and end of the results of the previous expansions, -then splits the remaining words. -

-If the value of -IFS +

Command +substitution allows the output of a command to replace +the command itself. There are two standard forms:

- -consists solely of IFS whitespace, + +

$(command)

+ +

or (deprecated)

+ + +

`command`.

+ +

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

+ +

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

+ +

There is an +alternate form of command substitution:

+ +

${c +command;}

+ +

which executes +command in the current execution environment and +captures its output, again with trailing newlines +removed.

+ +

The character +c following the open brace must be a space, tab, +newline, or |, and the close brace must be in a +position where a reserved word may appear (i.e., preceded by +a command terminator such as semicolon). Bash allows +the close brace to be joined to the remaining characters in +the word without being followed by a shell metacharacter as +a reserved word would usually require.

+ +

Any side effects +of command take effect immediately in the current +execution environment and persist in the current environment +after the command completes (e.g., the exit builtin +exits the shell).

+ +

This type of +command substitution superficially resembles executing an +unnamed shell function: local variables are created as when +a shell function is executing, and the return builtin +forces command to complete; however, the rest of the +execution environment, including the positional parameters, +is shared with the caller.

+ +

If the first +character following the open brace is a |, the +construct expands to the value of the REPLY shell +variable after command executes, without removing any +trailing newlines, and the standard output of command +remains the same as in the calling shell. Bash +creates REPLY as an initially-unset local variable +when command executes, and restores REPLY to +the value it had before the command substitution after +command completes, as with any local variable.

+ +

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, bash does +not perform word splitting and pathname expansion on the +results.

+ +

Arithmetic Expansion + +

+ + +

Arithmetic +expansion evaluates an arithmetic expression and substitutes +the result. The format for arithmetic expansion is:

+ + +

$((expression))

+ +

The +expression undergoes the same expansions as if it +were within double quotes, but unescaped double quote +characters in expression are not treated specially +and are removed. All tokens in the expression undergo +parameter and variable expansion, command substitution, and +quote removal. The result is treated as the arithmetic +expression to be evaluated. Since the way Bash handles +double quotes can potentially result in empty strings, +arithmetic expansion treats those as expressions that +evaluate to 0. Arithmetic expansions may be nested.

+ +

The evaluation +is performed according to the rules listed below under +ARITHMETIC EVALUATION. +If expression is invalid, bash prints a +message to standard error indicating failure, does not +perform the substitution, and does not execute the command +associated with the expansion.

+ +

Process Substitution + +

+ + +

Process +substitution allows a process’s input or output to +be referred to using a filename. It takes the form of +<(list) or +>(list). The process list is +run asynchronously, and its input or output appears as a +filename. This filename is passed as an argument to the +current command as the result of the expansion.

+ +

If the +>(list) form is used, writing to the +file provides input for list. If the +<(list) form is used, reading the +file obtains the output of list. No space may appear +between the < or > and the left +parenthesis, otherwise the construct would be interpreted as +a redirection.

+ +

Process +substitution is supported on systems that support named +pipes (FIFOs) or the /dev/fd method of naming +open files.

+ +

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

+ +

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. Words that were not +expanded are not split.

+ +

The shell treats +each character of IFS as a delimiter, +and splits the results of the other expansions into words +using these characters as field terminators.

+ +

An IFS +whitespace character is whitespace as defined above (see +Definitions) that appears in the value of +IFS. Space, tab, and +newline are always considered IFS whitespace, even if they +don’t appear in the locale’s space +category.

+ +

If +IFS is unset, field splitting acts as +if its value were +<space><tab><newline>, and treats +these characters as IFS whitespace. If the value of +IFS is null, no word splitting occurs, +but implicit null arguments (see below) are still +removed.

+ +

Word splitting +begins by removing sequences of IFS whitespace characters +from the beginning and end of the results of the previous +expansions, then splits the remaining words.

+ +

If the value of +IFS consists solely of IFS whitespace, any sequence of IFS whitespace characters delimits a field, so a field consists of characters that are not unquoted IFS -whitespace, and null fields result only from quoting. -

- -If -IFS - - -contains a non-whitespace character, then any character in -the value of -IFS - - -that is not IFS whitespace, -along with any adjacent IFS whitespace characters, delimits a field. -This means that adjacent non-IFS-whitespace delimiters produce a -null field. -A sequence of IFS whitespace characters also delimits a field. -

- -Explicit null arguments (" -" - or -'') are retained -and passed to commands as empty strings. -Unquoted implicit null arguments, resulting from the expansion of -parameters that have no values, are removed. -Expanding a parameter with no value within double quotes -produces a null field, -which is retained and passed to a command as an empty string. -

- -When a quoted null argument appears as part of a word whose expansion is +whitespace, and null fields result only from quoting.

+ +

If +IFS contains a non-whitespace +character, then any character in the value of +IFS that is not IFS whitespace, along +with any adjacent IFS whitespace characters, delimits a +field. This means that adjacent non-IFS-whitespace +delimiters produce a null field. A sequence of IFS +whitespace characters also delimits a field.

+ +

Explicit null +arguments ("" or '') are retained +and passed to commands as empty strings. Unquoted implicit +null arguments, resulting from the expansion of parameters +that have no values, are removed. Expanding a parameter with +no value within double quotes produces a null field, which +is retained and passed to a command as an empty string.

+ +

When a quoted +null argument appears as part of a word whose expansion is non-null, word splitting removes the null argument portion, -leaving the non-null expansion. -That is, the word +leaving the non-null expansion. That is, the word +“−d''” becomes “−d” +after word splitting and null argument removal.

+ +

Pathname Expansion + +

+ + +

After word +splitting, unless the −f option has been set, +bash scans each word for the characters *, +?, and [. If one of these characters appears, +and is not quoted, then the word is regarded as a +pattern, and replaced with a sorted list of filenames +matching the pattern (see Pattern +Matching below) subject to the value of the +GLOBSORT shell variable.

+ +

If no matching +filenames are found, and the shell option nullglob is +not enabled, the word is left unchanged. If the +nullglob option is set, and no matches are found, the +word is removed. If the failglob shell option is set, +and no matches are found, bash prints an error +message and does not execute the command. If the shell +option nocaseglob is enabled, the match is performed +without regard to the case of alphabetic characters.

+ +

When a pattern +is used for pathname expansion, the character +“.” at the start of a name or immediately +following a slash must be matched explicitly, unless the +shell option dotglob is set. In order to match the +filenames . and .., the pattern must begin +with “.” (for example, “.?”), even +if dotglob is set. If the globskipdots shell +option is enabled, the filenames . and .. +never match, even if the pattern begins with a +“.”. When not matching pathnames, the +“.” character is not treated specially.

+ +

When matching a +pathname, the slash character must always be matched +explicitly by a slash in the pattern, but in other matching +contexts it can be matched by a special pattern character as +described below under Pattern +Matching.

+ +

See the +description of shopt below under SHELL +BUILTIN COMMANDS for a description of the +nocaseglob, nullglob, globskipdots, +failglob, and dotglob shell options.

+ +

The +GLOBIGNORE shell variable may be used +to restrict the set of file names matching a pattern. +If GLOBIGNORE is set, each matching +file name that also matches one of the patterns in +GLOBIGNORE is removed from the list of +matches. If the nocaseglob option is set, the +matching against the patterns in +GLOBIGNORE is performed without regard +to case. The filenames . and .. are always +ignored when GLOBIGNORE is set and not +null. However, setting GLOBIGNORE to a +non-null value has the effect of enabling the dotglob +shell option, so all other filenames beginning with a +“.” match. To get the old behavior of ignoring +filenames beginning with a “.”, make +“.*” one of the patterns in +GLOBIGNORE . The dotglob option +is disabled when GLOBIGNORE is unset. +The GLOBIGNORE pattern matching honors the setting of +the extglob shell option.

+ +

The value of the +GLOBSORT shell variable controls how +the results of pathname expansion are sorted, as described +above under Shell Variables.

+ +

Pattern +Matching

+ +

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

+ +

The special +pattern characters have the following meanings:

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

*

 + + +

Matches any string, including +the null string. When the globstar shell option is +enabled, and * is used in a pathname expansion +context, two adjacent *s used as a single pattern +match all files and zero or more directories and +subdirectories. If followed by a /, two adjacent +*s match only directories and subdirectories.

-becomes -after word splitting and null argument removal. -  -

Pathname Expansion

+

?

 -After word splitting, -unless the --f -option has been set, -bash +

Matches any single character.

-scans each word for the characters -*, -?, +

[...]

 -and -[. -If one of these characters appears, and is not quoted, then the word is -regarded as a -pattern, +

Matches any one of the characters enclosed between the +brackets. This is known as a bracket expression and +matches a single character. A pair of characters separated +by a hyphen denotes a range expression; any character +that falls between those two characters, inclusive, using +the current locale’s collating sequence and character +set, matches. If the first character following the [ +is a ! or a ^ then any character not within +the range matches. To match a −, include it as +the first or last character in the set. To match a ], +include it as the first character in the set.

+ +

The sorting +order of characters in range expressions, and the characters +included in the range, are determined by the current locale +and the values of the LC_COLLATE or +LC_ALL shell variables, if set. To +obtain the traditional interpretation of range expressions, +where [a−d] is equivalent to [abcd], set +the value of the LC_COLLATE or LC_ALL shell +variables to C, or enable the globasciiranges +shell option.

+ +

Within a +bracket expression, character classes can be +specified using the syntax [:class:], +where class is one of the following classes defined +in the POSIX standard:

+ +

alnum alpha +ascii blank cntrl digit graph lower print punct space upper +word xdigit

+ +

A character +class matches any character belonging to that class. The +word character class matches letters, digits, and the +character _.

+ +

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

-and replaced with a sorted list of filenames matching the pattern -(see -Pattern Matching +

Within a +bracket expression, the syntax +[.symbol.] matches the collating symbol +symbol.

+ +

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

- -below) -subject to the value of the GLOBSORT shell variable. -

-If no matching filenames are found, -and the shell option -nullglob +

?(pattern-list)

-is not enabled, the word is left unchanged. -If the -nullglob +

Matches zero or one occurrence +of the given patterns.

-option is set, and no matches are found, -the word is removed. -If the -failglob -shell option is set, and no matches are found, -bash prints an error message and does not execute the command. -If the shell option -nocaseglob +

*(pattern-list)

+ +

Matches zero or more +occurrences of the given patterns.

-is enabled, the match is performed without regard to the case -of alphabetic characters. -

-When a pattern is used for pathname expansion, -the character +

+(pattern-list)

+ +

Matches one or more occurrences +of the given patterns.

+ -at the start of a name or immediately following a slash -must be matched explicitly, unless the shell option -dotglob +

@(pattern-list)

-is set. -In order to match the filenames +

Matches one of the given +patterns.

-. -and +

!(pattern-list)

-.., +

Matches anything except one of +the given patterns.

-the pattern must begin with +

The +extglob option changes the behavior of the parser, +since the parentheses are normally treated as operators with +syntactic meaning. To ensure that extended matching patterns +are parsed correctly, make sure that extglob is +enabled before parsing constructs containing the patterns, +including shell functions and command substitutions.

+ +

When matching +filenames, the dotglob shell option determines the +set of filenames that are tested: when dotglob is +enabled, the set of filenames includes all files beginning +with “.”, but . and .. must be +matched by a pattern or sub-pattern that begins with a dot; +when it is disabled, the set does not include any filenames +beginning with “.” unless the pattern or +sub-pattern begins with a “.”. If the +globskipdots shell option is enabled, the filenames +. and .. never appear in the set. As above, +“.” only has a special meaning when matching +filenames.

-(for example, +

Complicated +extended pattern matching against long strings is slow, +especially when the patterns contain alternations and the +strings contain multiple matches. Using separate matches +against shorter strings, or using arrays of strings instead +of a single long string, may be faster.

-even if -dotglob +

Quote Removal + +

-is set. -If the -globskipdots -shell option is enabled, the filenames +

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

-. +

REDIRECTION + +

-and -.. +

Before a command +is executed, its input and output may be redirected +using a special notation interpreted by the shell. +Redirection allows commands’ file handles to be +duplicated, opened, closed, made to refer to different +files, and can change the files the command reads from and +writes to. When used with the exec builtin, +redirections modify file handles in 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 {varname}. In this +case, for each redirection operator except +>&− and <&−, the +shell allocates a file descriptor greater than or equal to +10 and assigns it to varname. If {varname} +precedes >&− or <&−, +the value of varname defines the file descriptor to +close. If {varname} is supplied, the redirection +persists beyond the scope of the command, which allows the +shell programmer to manage the file descriptor’s +lifetime manually without using the exec builtin. The +varredir_close shell option manages this +behavior.

+ +

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

-never match, even if the pattern begins with a +

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

-When not matching pathnames, the +

The order of +redirections is significant. For example, the command

-character is not treated specially. -

+

ls > +dirlist 2>&1

-When matching a pathname, the slash character must always be -matched explicitly by a slash in the pattern, but in other matching -contexts it can be matched by a special pattern character as described -below under -Pattern Matching. +

directs both +standard output and standard error to the file +dirlist, while the command

- -

+

ls +2>&1 > dirlist

+ +

directs only the +standard output to file dirlist, because the standard +error was directed to the standard output before the +standard output was redirected to dirlist.

+ +

Bash +handles several filenames specially when they are used in +redirections, as described in the following table. If the +operating system on which bash is running provides +these special files, bash uses them; otherwise it +emulates them internally with the behavior described +below.

+ +

/dev/fd/fd

-See the description of -shopt +

If fd is a valid +integer, duplicate file descriptor fd.

-below under -SHELL BUILTIN COMMANDS +

/dev/stdin

- -for a description of the -nocaseglob, +

File descriptor 0 is +duplicated.

-nullglob, +

/dev/stdout

-globskipdots, +

File descriptor 1 is +duplicated.

-failglob, +

/dev/stderr

-and -dotglob +

File descriptor 2 is +duplicated.

-shell options. -

-The -GLOBIGNORE +

/dev/tcp/host/port

- -shell variable may be used to restrict the set of file names matching a -pattern. +

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

-If -GLOBIGNORE - -is set, each matching file name that also matches one of the patterns in -GLOBIGNORE +

/dev/udp/host/port

- -is removed from the list of matches. -If the nocaseglob option is set, the matching against the patterns in -GLOBIGNORE +

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

- -is performed without regard to case. -The filenames +

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.

-and +

Redirecting Input + +

-.. -are always ignored when -GLOBIGNORE +

Redirecting +input opens the file whose name results from the expansion +of word for reading on file descriptor n, or +the standard input (file descriptor 0) if n is not +specified.

- -is set and not null. -However, setting -GLOBIGNORE +

The general +format for redirecting input is:

- -to a non-null value has the effect of enabling the -dotglob -shell option, so all other filenames beginning with a +

[n]<word

-match. -To get the old behavior of ignoring filenames beginning with a +

Redirecting Output + +

-make -one of the patterns in -GLOBIGNORE +

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

- -. -The -dotglob +

The general +format for redirecting output is:

-option is disabled when -GLOBIGNORE - -is unset. -The -GLOBIGNORE +

[n]>word

-pattern matching honors the setting of the extglob shell -option. -

+

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

-The value of the -GLOBSORT +

Appending Redirected Output + +

- -shell variable controls how the results of pathname expansion are sorted, -as described above under -Shell Variables. -

- -Pattern Matching - -

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

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

- - -

-
-
* - -
-Matches any string, including the null string. -When the globstar shell option is enabled, and * is used in -a pathname expansion context, two adjacent *s used as a single -pattern match all files and zero or more directories and -subdirectories. -If followed by a /, two adjacent *s match only directories -and subdirectories. -
? - -
-Matches any single character. -
[...] - -
- -Matches any one of the characters enclosed between the brackets. -This is known as a bracket expression -and matches a single character. -A pair of characters separated by a hyphen denotes a -range expression; -any character that falls between those two characters, inclusive, -using the current locale's collating sequence and character set, matches. -If the first character following the -[ - -is a -! - -or a -^ - -then any character not within the range matches. -To match a --, - -include it as the first or last character in the set. -To match a -], - -include it as the first character in the set. -
-The sorting order of characters in range expressions, -and the characters included in the range, -are determined by the current locale and the values of the -LC_COLLATE - - -or -LC_ALL - - -shell variables, if set. -To obtain the traditional interpretation of range expressions, where -[a-d] - -is equivalent to -[abcd], - -set the value of the -LC_COLLATE - -or -LC_ALL - -shell variables to -C, - -or enable the -globasciiranges - -shell option. -
-Within a bracket expression, -character classes can be specified using the syntax -[:class:], where class is one of the -following classes defined in the -POSIX -standard: -
-
- - - -alnum alpha ascii blank cntrl digit graph lower print punct space upper word xdigit -
- -
-A character class matches any character belonging to that class. -The word character class matches letters, digits, and the character _. -
-Within a bracket expression, -an equivalence class can be specified using the syntax -[=c=], which matches all characters with the -same collation weight (as defined by the current locale) as -the character c. -
-Within a bracket expression, -the syntax [.symbol.] matches the collating symbol -symbol. -
- -

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

- - -

-
-
?(pattern-list)
-Matches zero or one occurrence of the given patterns. -
*(pattern-list)
-Matches zero or more occurrences of the given patterns. -
+(pattern-list)
-Matches one or more occurrences of the given patterns. -
@(pattern-list)
-Matches one of the given patterns. -
!(pattern-list)
-Matches anything except one of the given patterns. -
- - -

- -The extglob option changes the behavior of the parser, since the -parentheses are normally treated as operators with syntactic meaning. -To ensure that extended matching patterns are parsed correctly, make sure -that extglob is enabled before parsing constructs containing the -patterns, including shell functions and command substitutions. -

- -When matching filenames, the dotglob shell option determines -the set of filenames that are tested: -when dotglob is enabled, the set of filenames includes all files -beginning with - -but - -. +

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

-and - -.. +

The general +format for appending output is:

-must be matched by a pattern or sub-pattern that begins with a dot; -when it is disabled, the set does not -include any filenames beginning with -unless the pattern or sub-pattern begins with a +

[n]>>word

-If the -globskipdots +

Redirecting Standard Output and Standard Error + +

-shell option is enabled, the filenames - -. - -and - -.. - -never appear in the set. -As above, - -only has a special meaning when matching filenames. -

- -Complicated extended pattern matching against long strings is slow, -especially when the patterns contain alternations and the strings -contain multiple matches. -Using separate matches against shorter strings, or using arrays of -strings instead of a single long string, may be faster. -  -

Quote Removal

-After the preceding expansions, all unquoted occurrences of the -characters -\, +

This construct +redirects both the standard output (file descriptor 1) and +the standard error output (file descriptor 2) to the file +whose name is the expansion of word.

-', +

There are two +formats for redirecting standard output and standard +error:

-and " - that did not result from one of the above -expansions are removed. -  -

REDIRECTION

-Before a command is executed, its input and output may be -redirected +

&>word

-using a special notation interpreted by the shell. -Redirection allows commands' file handles to be -duplicated, opened, closed, -made to refer to different files, -and can change the files the command reads from and writes to. -When used with the exec builtin, -redirections modify file handles in 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 {varname}. -In this case, for each redirection operator except ->&- - -and -<&-, - -the shell allocates a file descriptor greater -than or equal to 10 and assigns it to varname. -If {varname} precedes ->&- - -or -<&-, - -the value of varname defines the file descriptor to close. -If {varname} is supplied, the redirection persists beyond -the scope of the command, which allows the shell programmer to -manage the file descriptor's lifetime manually without using -the exec builtin. -The varredir_close shell option manages this behavior. -

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

- -The word following the redirection operator in the following -descriptions, unless otherwise noted, is subjected to -brace expansion, -tilde expansion, -parameter and variable expansion, -command substitution, -arithmetic expansion, -quote removal, -pathname expansion, -and word splitting. -If it expands to more than one word, -bash +

and

-reports an error. -

- -The order of redirections is significant. -For example, -the command -

-

- -ls > dirlist 2>&1 -

-

+

>&word

-directs both standard output and standard error to the file -dirlist, +

Of the two +forms, the first is preferred. This is semantically +equivalent to

-while the command -
-

-ls 2>&1 > dirlist -

+

>word +2>&1

-

+

When using the +second form, word may not expand to a number or +−. If it does, other redirection operators +apply (see Duplicating File Descriptors below) for +compatibility reasons.

-directs only the standard output to file -dirlist, +

Appending Standard Output and Standard Error + +

-because the standard error was directed to the standard output -before the standard output was redirected to -dirlist. -

+

This construct +appends both the standard output (file descriptor 1) and the +standard error output (file descriptor 2) to the file whose +name is the expansion of word.

-Bash handles several filenames specially when they are used in -redirections, as described in the following table. -If the operating system on which bash is running provides these -special files, bash uses them; otherwise it emulates them -internally with the behavior described below. -
-

+

The format for +appending standard output and standard error is:

-
-
/dev/fd/fd +

&>>word

-
-If fd is a valid integer, duplicate file descriptor fd. -
/dev/stdin +

This is +semantically equivalent to

-
-File descriptor 0 is duplicated. -
/dev/stdout -
-File descriptor 1 is duplicated. -
/dev/stderr +

>>word +2>&1

-
-File descriptor 2 is duplicated. -
/dev/tcp/host/port +

(see +Duplicating File Descriptors below).

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

Here Documents + +

-
-If host is a valid hostname or Internet address, and port -is an integer port number or service name, bash attempts to open -the corresponding UDP socket. -
+

This type of +redirection instructs the shell to read input from the +current source until it reads a line containing only +delimiter (with no trailing blanks). All of the lines +read up to that point then become the standard input (or +file descriptor n if n is specified) for a +command.

+ +

The format of +here-documents is:

+ + +

[n]<<[−]word +
+here-document
+delimiter

+ +

The shell does +not perform parameter and variable expansion, command +substitution, arithmetic expansion, or pathname expansion on +word.

+ +

If any part of +word is quoted, the delimiter is the result of +quote removal on word, and the lines in the +here-document are not expanded. If word is unquoted, +the delimiter is word itself, and the +here-document text is treated similarly to a double-quoted +string: all lines of the here-document are subjected to +parameter expansion, command substitution, and arithmetic +expansion, the character sequence \<newline> is +treated literally, and \ must be used to quote the +characters \, $, and `; however, double +quote characters have no special meaning.

+ +

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

-

+

If the delimiter +is not quoted, the shell treats the \<newline> +sequence as a line continuation: the two lines are joined +and the backslash-newline is removed. This happens while +reading the here-document, before the check for the ending +delimiter, so joined lines can form the end delimiter.

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

+

Here Strings + +

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

Redirecting Input

-Redirecting input opens the file whose name results from -the expansion of -word +

A variant of +here documents, the format is:

-for reading on file descriptor -n, -or the standard input (file descriptor 0) if -n +

[n]<<<word

-is not specified. -

+

The word +undergoes tilde expansion, parameter and variable expansion, +command substitution, arithmetic expansion, and quote +removal. Pathname expansion and word splitting are not +performed. The result is supplied as a single string, with a +newline appended, to the command on its standard input (or +file descriptor n if n is specified).

-The general format for redirecting input is: -
-

+

Duplicating File Descriptors + +

-[n]<word -
-  -

Redirecting Output

+

The redirection +operator

-Redirecting output opens the file whose name results from -the expansion of -word -for writing on file descriptor -n, +

[n]<&word

-or the standard output (file descriptor 1) if -n +

is used to +duplicate input file descriptors. If word expands to +one or more digits, file descriptor n is made to be a +copy of that file descriptor. It is a redirection error if +the digits in word do not specify a file descriptor +open for input. If word evaluates to −, +file descriptor n is closed. If n is not +specified, this uses the standard input (file descriptor +0).

-is not specified. -If the file does not exist it is created; -if it does exist it is truncated to zero size. -

+

The operator

-The general format for redirecting output is: -
-

-[n]>word -

+

[n]>&word

-

+

is used +similarly to duplicate output file descriptors. If n +is not specified, this uses the standard output (file +descriptor 1). It is a redirection error if the digits in +word do not specify a file descriptor open for +output. If word evaluates to −, file +descriptor n is closed. As a special case, if +n is omitted, and word does not expand to one +or more digits or −, this redirects the +standard output and standard error as described +previously.

-If the redirection operator is ->, +

Moving File Descriptors + +

-and the -noclobber -option to the -set +

The redirection +operator

+ + +

[n]<&digit−

+ +

moves the file +descriptor digit to file descriptor n, or the +standard input (file descriptor 0) if n is not +specified. digit is closed after being duplicated to +n.

+ +

Similarly, the +redirection operator

+ + +

[n]>&digit−

+ +

moves the file +descriptor digit to file descriptor n, or the +standard output (file descriptor 1) if n is not +specified.

+ +

Opening File Descriptors for Reading and Writing + +

+ + +

The redirection +operator

+ + +

[n]<>word

+ +

opens the file +whose name is the expansion of word for both reading +and writing on file descriptor n, or on file +descriptor 0 if n is not specified. If the file does +not exist, it is created.

+ +

ALIASES + +

+ + +

Aliases +allow a string to be substituted for a word that is in a +position in the input where it can be the first word of a +simple command. Aliases have names and corresponding values +that are set and unset using the alias and +unalias builtin commands (see SHELL BUILTIN +COMMANDS below).

+ +

If the shell +reads an unquoted word in the right position, it checks the +word to see if it matches an alias name. If it matches, the +shell replaces the word with the alias value, and reads that +value as if it had been read instead of the word. The shell +doesn’t look at any characters following the word +before attempting alias substitution.

+ +

The characters +/, $, `, and = and any of the +shell metacharacters or quoting characters listed +above may not appear in an alias name. The replacement text +may contain any valid shell input, including shell +metacharacters. The first word of the replacement text is +tested for aliases, but a word that is identical to an alias +being expanded is not expanded a second time. This means +that one may alias ls to ls −F, for +instance, and bash does not try to recursively expand +the replacement text.

+ +

If the last +character of the alias value is a blank, the shell +checks the next command word following the alias for alias +expansion.

+ +

Aliases are +created and listed with the alias command, and +removed with the unalias command.

+ +

There is no +mechanism for using arguments in the replacement text. If +arguments are needed, use a shell function (see +FUNCTIONS below) instead.

+ +

Aliases are not +expanded when the shell is not interactive, unless the +expand_aliases shell option is set using shopt +(see the description of shopt under SHELL +BUILTIN COMMANDS below).

+ +

The rules +concerning the definition and use of aliases are somewhat +confusing. Bash always reads at least one complete +line of input, and all lines that make up a compound +command, before executing any of the commands on that line +or the compound command. 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 shell reads the next line of +input, and an alias definition in a compound command does +not take effect until the shell parses and executes the +entire compound command. The commands following the alias +definition on that line, or in the rest of a compound +command, 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 command. As a consequence, aliases defined in a +function are not available until after that function is +executed. To be safe, always put alias definitions on a +separate line, and do not use alias in compound +commands.

+ +

For almost every +purpose, shell functions are preferable to aliases.

+ +

FUNCTIONS + +

+ + +

A shell +function, defined as described above under 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 shell +executes the list of commands associated with that function +name. Functions are executed in the context of the calling +shell; there is no new process 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 # is updated to reflect the new positional +parameters. Special parameter 0 is unchanged. The +first element of the FUNCNAME variable +is set to the name of the function while the function is +executing.

+ +

All other +aspects of the shell execution environment are identical +between a function and its caller with these exceptions: the +DEBUG and RETURN traps (see the +description of the trap builtin under SHELL +BUILTIN COMMANDS below) are not inherited unless +the function has been given the trace attribute (see +the description of the declare builtin +below) or the −o functrace shell option has +been enabled with the set builtin (in which case all +functions inherit the DEBUG and RETURN traps), +and the ERR trap is not inherited +unless the −o errtrace shell option has been +enabled.

+ +

Variables local +to the function are declared with the local builtin +command (local variables). Ordinarily, variables and +their values are shared between the function and its caller. +If a variable is declared local, the variable’s +visible scope is restricted to that function and its +children (including the functions it calls).

+ +

In the following +description, the current scope is a currently- +executing function. Previous scopes consist of that +function’s caller and so on, back to the +“global” scope, where the shell is not executing +any shell function. A local variable at the current scope is +a variable declared using the local or declare +builtins in the function that is currently executing.

+ +

Local variables +“shadow” variables with the same name declared +at previous scopes. For instance, a local variable declared +in a function hides variables with the same name declared at +previous scopes, including global variables: references and +assignments refer to the local variable, leaving the +variables at previous scopes unmodified. When the function +returns, the global variable is once again visible.

+ +

The shell uses +dynamic scoping to control a variable’s +visibility within functions. With dynamic scoping, visible +variables and their values are a result of the sequence of +function calls that caused execution to reach the current +function. The value of a variable that a function sees +depends on its value within its caller, if any, whether that +caller is the global scope or another shell function. This +is also the value that a local variable declaration shadows, +and the value that is restored when the function +returns.

+ +

For example, if +a variable var is declared as local in function +func1, and func1 calls another function +func2, references to var made from within +func2 resolve to the local variable var from +func1, shadowing any global variable named +var.

+ +

The unset +builtin also acts using the same dynamic scope: if a +variable is local to the current scope, unset unsets +it; otherwise the unset will refer to the variable found in +any calling scope as described above. If a variable at the +current local scope is unset, it remains so (appearing as +unset) until it is reset in that scope or until the function +returns. Once the function returns, any instance of the +variable at a previous scope becomes visible. If the unset +acts on a variable at a previous scope, any instance of a +variable with that name that had been shadowed becomes +visible (see below how the localvar_unset shell +option changes this behavior).

+ +

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

+ +

The +−f option to the declare or +typeset builtin commands lists function names and +definitions. The −F option to declare or +typeset lists the function names only (and optionally +the source file and line number, if the extdebug +shell option is enabled). Functions may be exported so that +child shell processes (those created when executing a +separate shell invocation) automatically have them defined +with the −f option to the export +builtin. The −f option to the unset +builtin deletes a function definition.

+ +

Functions may be +recursive. The FUNCNEST variable may be used to limit +the depth of the function call stack and restrict the number +of function invocations. By default, bash imposes no +limit on the number of recursive calls.

+ +

ARITHMETIC EVALUATION + +

+ + +

The shell allows +arithmetic expressions to be evaluated, under certain +circumstances (see the let and declare builtin +commands, the (( compound command, the arithmetic +for command, the [[ conditional command, and +Arithmetic Expansion).

+ +

Evaluation is +done in the largest fixed-width integers available, with no +check for overflow, though division by 0 is trapped and +flagged as an error. The operators and their precedence, +associativity, and values are the same as in the C language. +The following list of operators is grouped into levels of +equal-precedence operators. The levels are listed in order +of decreasing precedence.
+id++ id−−

+ +

variable post-increment and +post-decrement

-builtin command has been enabled, the redirection fails if the file -whose name results from the expansion of word exists and is -a regular file. -If the redirection operator is ->|, +

++id +−−id

-or the redirection operator is -> +

variable pre-increment and +pre-decrement

-and the -noclobber + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
-option to the -set -builtin is not enabled, -bash attempts the redirection -even if the file named by word exists. -  -

Appending Redirected Output

+

− +

 -Redirecting output in this fashion opens -the file whose name results from the expansion of -word -for appending on file descriptor -n, +

unary minus and plus

 +
-or the standard output (file descriptor 1) if -n -is not specified. -If the file does not exist it is created. -

+

! ~

 -The general format for appending output is: -
-

-[n]>>word -

+

logical and bitwise negation

 +
-  -

Redirecting Standard Output and Standard Error

-This construct redirects both the -standard output (file descriptor 1) and -the standard error output (file descriptor 2) -to the file whose name is the expansion of -word. +

**

 -

-There are two formats for redirecting standard output and -standard error: -

-

+

exponentiation

 +
-&>word - -and -
->&word -
+

* / %

 -

-Of the two forms, the first is preferred. -This is semantically equivalent to -

-

+

multiplication, division, remainder

 +
->word 2>&1 - -

+

+ −

 -When using the second form, word may not expand to a number or --. -If it does, other redirection operators apply -(see Duplicating File Descriptors below) for compatibility -reasons. -  -

Appending Standard Output and Standard Error

-This construct appends both the -standard output (file descriptor 1) and -the standard error output (file descriptor 2) -to the file whose name is the expansion of -word. +

addition, subtraction

 +
-

-The format for appending standard output and standard error is: -

-

+

<< >>

 -&>>word - -

+

left and right bitwise shifts

 +
-This is semantically equivalent to -
-

+

<= >= < >

->>word 2>&1 -
+

comparison

-

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
-(see Duplicating File Descriptors below). -  -

Here Documents

-This type of redirection instructs the shell to read input from the -current source until it reads a line containing only -delimiter +

== !=

 -(with no trailing blanks). -All of the lines read up to that point then become the standard -input (or file descriptor n if n is specified) for a command. -

-The format of here-documents is: -

-

+

equality and inequality

 +
-
-[n]<<[-]word
-        here-document
-delimiter
-
- +

&

 -

-The shell does not perform -parameter and variable expansion, command substitution, -arithmetic expansion, or pathname expansion on -word. +

bitwise AND

 +
-

-If any part of -word +

^

 -is quoted, the -delimiter -is the result of quote removal on -word, +

bitwise exclusive OR

 +
-and the lines in the here-document are not expanded. -If word is unquoted, the -delimiter -is word itself, -and the here-document text is treated similarly to a double-quoted string: -all lines of the here-document are subjected to -parameter expansion, command substitution, and arithmetic expansion, -the character sequence -\<newline> +

|

 -is treated literally, and -\ -must be used to quote the characters -\, +

bitwise OR

 +
-$, -and -`; +

&&

 -however, double quote characters have no special meaning. -

-If the redirection operator is -<<-, +

logical AND

 +
-then the shell strips all leading tab characters from input lines -and the line containing -delimiter. -This allows -here-documents within shell scripts to be indented in a -natural fashion. -

+

||

 -If the delimiter is not quoted, the -\<newline> -sequence is treated as a line continuation: the two lines are joined -and the backslash-newline is removed. -This happens while reading the here-document, before the check for -the ending delimiter, so joined lines can form the end delimiter. -  -

Here Strings

+

logical OR

 +
-A variant of here documents, the format is: -

-

-

-[n]<<<word
-
+

expr?expr:expr

-
+

conditional operator

-

+

= *= /= %= += −= +<<= >>= &= ^= |=

-The word undergoes -tilde expansion, parameter and variable expansion, -command substitution, arithmetic expansion, and quote removal. -Pathname expansion and word splitting are not performed. -The result is supplied as a single string, with a newline appended, -to the command on its -standard input (or file descriptor n if n is specified). -  -

Duplicating File Descriptors

+

assignment

-The redirection operator -
-

+

expr1 , +expr2

-[n]<&word -
+

comma

-

+

Shell variables +are allowed as operands; parameter expansion is performed +before the expression is evaluated. Within an expression, +shell variables may also be referenced by name without using +the parameter expansion syntax. This means you can use +"x", where x is a shell variable name, in +an arithmetic expression, and the shell will evaluate its +value as an expression and use the result. A shell variable +that is null or unset evaluates to 0 when referenced by name +in an expression.

-is used to duplicate input file descriptors. -If -word +

The value of a +variable is evaluated as an arithmetic expression when it is +referenced, or when a variable which has been given the +integer attribute using declare −i is +assigned a value. A null value evaluates to 0. A shell +variable need not have its integer attribute enabled +to be used in an expression.

-expands to one or more digits, file descriptor -n +

Integer +constants follow the C language definition, without suffixes +or character constants. Constants with a leading 0 are +interpreted as octal numbers. A leading 0x or 0X denotes +hexadecimal. Otherwise, numbers take the form +[base#]n, where the optional base is a decimal +number between 2 and 64 representing the arithmetic base, +and n is a number in that base. If base# is +omitted, then base 10 is used. When specifying n, if +a non-digit is required, the digits greater than 9 are +represented by the lowercase letters, the uppercase letters, +@, and _, in that order. If base is less than or +equal to 36, lowercase and uppercase letters may be used +interchangeably to represent numbers between 10 and 35.

-is made to be a copy of that file descriptor. -It is a redirection error if the digits in -word +

Operators are +evaluated in precedence order. Sub-expressions in +parentheses are evaluated first and may override the +precedence rules above.

-do not specify a file descriptor open for input. -If -word +

CONDITIONAL EXPRESSIONS + +

-evaluates to --, -file descriptor -n +

Conditional +expressions are used by the [[ compound command and +the test and [ builtin commands to test file +attributes and perform string and arithmetic comparisons. +The test and [ commands determine their +behavior based on the number of arguments; see the +descriptions of those commands for any other +command-specific actions.

-is closed. -If -n +

Expressions are +formed from the unary or binary primaries listed below. +Unary expressions are often used to examine the status of a +file or shell variable. Binary operators are used for +string, numeric, and file attribute comparisons.

-is not specified, this uses the standard input (file descriptor 0). -

+

Bash +handles several filenames specially when they are used in +expressions. If the operating system on which bash is +running provides these special files, bash will use them; +otherwise it will emulate them internally with this +behavior: If any file argument to one of the +primaries is of the form /dev/fd/n, then bash +checks file descriptor n. If the file argument +to one of the primaries is one of /dev/stdin, +/dev/stdout, or /dev/stderr, bash +checks file descriptor 0, 1, or 2, respectively.

-The operator -
-

+

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

-[n]>&word -
+

When used with +[[, or when the shell is in posix mode, the +< and > operators sort lexicographically +using the current locale. When the shell is not in posix +mode, the test command sorts using ASCII ordering. +
+−a file

-

+

True if file exists.

-is used similarly to duplicate output file descriptors. -If -n +

−b file

-is not specified, this uses the standard output (file descriptor 1). -It is a redirection error if the digits in -word +

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

-do not specify a file descriptor open for output. -If -word +

−c file

-evaluates to --, +

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

-file descriptor -n +

−d file

-is closed. -As a special case, if n is omitted, -and word does not expand to one or more digits or -, -this redirects the standard output and standard error as described -previously. -  -

Moving File Descriptors

+

True if file exists and +is a directory.

-The redirection operator -
-

+

−e file

-[n]<&digit- -
+

True if file exists.

-

+

−f file

-moves the file descriptor digit to file descriptor -n, +

True if file exists and +is a regular file.

-or the standard input (file descriptor 0) if n is not specified. -digit is closed after being duplicated to n. -

+

−g file

-Similarly, the redirection operator -
-

+

True if file exists and +is set-group-id.

-[n]>&digit- -
+

−h file

-

+

True if file exists and +is a symbolic link.

-moves the file descriptor digit to file descriptor -n, +

−k file

-or the standard output (file descriptor 1) if n is not specified. -  -

Opening File Descriptors for Reading and Writing

+

True if file exists and +its “sticky” bit is set.

-The redirection operator -
-

+

−p file

-[n]<>word -
+

True if file exists and +is a named pipe (FIFO).

-

+

−r file

-opens the file whose name is the expansion of -word +

True if file exists and +is readable.

-for both reading and writing on file descriptor -n, +

−s file

-or on file descriptor 0 if -n +

True if file exists and +has a size greater than zero.

-is not specified. -If the file does not exist, it is created. -  -

ALIASES

+ + + + + + + +
-Aliases allow a string to be substituted for a word that is in -a position in the input where it can be the first word of a simple -command. -Aliases have names and corresponding values that are set -and unset using the alias and unalias builtin commands -(see -SHELL BUILTIN COMMANDS - - -below). -

- -If the shell reads an unquoted word in the right position, it checks -the word to see if it matches an alias name. -If it matches, the shell -replaces the word with the alias value, and reads that value as if it -had been read instead of the word. -The shell doesn't look at any characters following the word before -attempting alias substitution. -

- -The characters /, $, `, and = and -any of the shell metacharacters or quoting characters -listed above may not appear in an alias name. -The replacement text may contain any valid shell input, -including shell metacharacters. -The first word of the replacement text is tested -for aliases, but a word that is identical to an alias being expanded -is not expanded a second time. -This means that one may alias -ls - -to -ls -F, - -for instance, and -bash - -does not try to recursively expand the replacement text. -

- -If the last character of the alias value is a -blank, - -the shell checks the next command -word following the alias for alias expansion. -

- -Aliases are created and listed with the -alias - -command, and removed with the -unalias - -command. -

- -There is no mechanism for using arguments in the replacement text. -If arguments are needed, use a shell function (see -FUNCTIONS - - -below) instead. -

- -Aliases are not expanded when the shell is not interactive, unless -the -expand_aliases - -shell option is set using -shopt - -(see the description of -shopt - -under -SHELL BUILTIN COMMANDS - - -below). -

- -The rules concerning the definition and use of aliases are -somewhat confusing. -Bash - -always reads at least one complete line of input, -and all lines that make up a compound command, -before executing any of the commands on that line or the compound command. -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 shell reads the next line of input, -and an alias definition in a compound command does not take -effect until the shell parses and executes the entire compound command. -The commands following the alias definition -on that line, -or in the rest of a compound command, -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 command. -As a consequence, aliases -defined in a function are not available until after that -function is executed. -To be safe, always put -alias definitions on a separate line, and do not use -alias - -in compound commands. -

- -For almost every purpose, shell functions are preferable to aliases. -  -

FUNCTIONS

- -A shell function, defined as described above under -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 shell executes -the list of commands associated with that function name. -Functions are executed in the context of the -calling shell; there is no new process 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 -# - -is updated to reflect the new positional parameters. -Special parameter 0 is unchanged. -The first element of the -FUNCNAME - - -variable is set to the name of the function while the function -is executing. -

- -All other aspects of the shell execution -environment are identical between a function and its caller -with these exceptions: the -DEBUG - - -and -RETURN - -traps (see the description of the -trap - -builtin under -SHELL BUILTIN COMMANDS - - -below) are not inherited unless the function has been given the -trace attribute (see the description of the -declare - - -builtin below) or the --o functrace shell option has been enabled with -the set builtin -(in which case all functions inherit the DEBUG and RETURN traps), -and the -ERR - - -trap is not inherited unless the -o errtrace shell option has -been enabled. -

- -Variables local to the function are declared with the -local - -builtin command (local variables). -Ordinarily, variables and their values -are shared between the function and its caller. -If a variable is declared local, the variable's visible scope -is restricted to that function and its children (including the functions -it calls). -

- -In the following description, the current scope is a currently- -executing function. -Previous scopes consist of that function's caller and so on, -back to the - -scope, where the shell is not executing any shell function. -A local variable at the current scope is a variable -declared using the local or declare builtins in the -function that is currently executing. -

- -Local variables - -variables with the same name declared at previous scopes. -For instance, a local variable declared in a function -hides variables with the same name declared at previous scopes, -including global variables: references and assignments -refer to the local variable, leaving the variables -at previous scopes unmodified. -When the function returns, the global variable is once again visible. -

- -The shell uses dynamic scoping to control a variable's visibility -within functions. -With dynamic scoping, visible variables and their values -are a result of the sequence of function calls that caused execution -to reach the current function. -The value of a variable that a function sees depends -on its value within its caller, if any, whether that caller is -the global -scope or another shell function. -This is also the value that a local variable -declaration shadows, -and the value that is restored when the function returns. -

- -For example, if a variable var is declared as local in function -func1, and func1 calls another function func2, -references to var made from within func2 resolve to the -local variable var from func1, shadowing any global variable -named var. -

- -The unset builtin also acts using the same dynamic scope: if a -variable is local to the current scope, unset unsets it; -otherwise the unset will refer to the variable found in any calling scope -as described above. -If a variable at the current local scope is unset, it remains so -(appearing as unset) -until it is reset in that scope or until the function returns. -Once the function returns, any instance of the variable at a previous -scope becomes visible. -If the unset acts on a variable at a previous scope, any instance of a -variable with that name that had been shadowed becomes visible -(see below how the localvar_unset shell option changes this behavior). -

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

- -The --f - -option to the -declare - -or -typeset - -builtin commands -lists function names and definitions. -The --F - -option to -declare - -or -typeset - -lists the function names only -(and optionally the source file and line number, if the extdebug -shell option is enabled). -Functions may be exported so that child shell processes -(those created when executing a separate shell invocation) -automatically have them defined with the --f - -option to the -export - -builtin. -The -f option to -the -unset - -builtin deletes a function definition. -

- -Functions may be recursive. -The FUNCNEST variable may be used to limit the depth of the -function call stack and restrict the number of function invocations. -By default, bash imposes no limit on the number of recursive calls. -  -

ARITHMETIC EVALUATION

- -The shell allows arithmetic expressions to be evaluated, under -certain circumstances -(see the let and declare builtin commands, -the (( compound command, -the arithmetic for command, -the [[ conditional command, -and Arithmetic Expansion). -

- -Evaluation is done in the largest fixed-width integers available, -with no check for overflow, -though division by 0 is trapped and flagged as an error. -The operators and their precedence, associativity, and values -are the same as in the C language. -The following list of operators is grouped into levels of -equal-precedence operators. -The levels are listed in order of decreasing precedence. -

- - -

-
id++ id-- - -
-variable post-increment and post-decrement -
++id --id - -
-variable pre-increment and pre-decrement -
- + - -
-unary minus and plus -
! ~ - -
-logical and bitwise negation -
** - -
-exponentiation -
* / % - -
-multiplication, division, remainder -
+ - - -
-addition, subtraction -
<< >> - -
-left and right bitwise shifts -
<= >= < > - -
-comparison -
== != - -
-equality and inequality -
& - -
-bitwise AND -
^ - -
-bitwise exclusive OR -
| - -
-bitwise OR -
&& - -
-logical AND -
|| - -
-logical OR -
expr?expr:expr - -
-conditional operator -
= *= /= %= += -= <<= >>= &= ^= |= - -
-assignment -
expr1 , expr2 - -
-comma - -
-

- -Shell variables are allowed as operands; parameter expansion is -performed before the expression is evaluated. -Within an expression, shell variables may also be referenced by name -without using the parameter expansion syntax. -This means you can use "x", where x is a shell variable name, -in an arithmetic expression, and the shell will evaluate its value as -an expression and use the result. -A shell variable that is null or unset evaluates to 0 when referenced -by name in an expression. -

- -The value of a variable is evaluated as an arithmetic expression -when it is referenced, or when a variable which has been given the -integer attribute using declare -i is assigned a value. -A null value evaluates to 0. -A shell variable need not have its integer attribute -enabled to be used in an expression. -

- -Integer constants follow the C language definition, without suffixes or -character constants. -Constants with a leading 0 are interpreted as octal numbers. -A leading 0x or 0X denotes hexadecimal. -Otherwise, numbers take the form [base#]n, where the optional base -is a decimal number between 2 and 64 representing the arithmetic -base, and n is a number in that base. -If base# is omitted, then base 10 is used. -When specifying n, -if a non-digit is required, -the digits greater than 9 are represented by the lowercase letters, -the uppercase letters, @, and _, in that order. -If base is less than or equal to 36, lowercase and uppercase -letters may be used interchangeably to represent numbers between 10 -and 35. -

- -Operators are evaluated in precedence order. -Sub-expressions in parentheses are evaluated first -and may override the precedence rules above. -  -

CONDITIONAL EXPRESSIONS

- -Conditional expressions are used by the [[ compound command and -the test and [ builtin commands to test file attributes -and perform string and arithmetic comparisons. -The test and [ commands determine their behavior based on -the number of arguments; see the descriptions of those commands for any -other command-specific actions. -

- -Expressions are formed from the unary or binary primaries listed below. -Unary expressions are often used to examine the status of a file -or shell variable. -Binary operators are used for string, numeric, and file attribute -comparisons. -

- -Bash handles several filenames specially when they are used in -expressions. -If the operating system on which bash is running provides these -special files, bash will use them; otherwise it will emulate them -internally with this behavior: -If any file argument to one of the primaries is of the form - -/dev/fd/n, - -then bash checks file descriptor n. -If the file argument to one of the primaries is one of - -/dev/stdin, - - -/dev/stdout, - -or - -/dev/stderr, - -bash checks file descriptor 0, 1, or 2, respectively. -

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

- -When used with [[, -or when the shell is in posix mode, -the < and > operators sort -lexicographically using the current locale. -When the shell is not in posix mode, -the test command sorts using ASCII ordering. -

- - -

-
-a file - -
-True if file exists. -
-b file - -
-True if file exists and is a block special file. -
-c file - -
-True if file exists and is a character special file. -
-d file - -
-True if file exists and is a directory. -
-e file - -
-True if file exists. -
-f file - -
-True if file exists and is a regular file. -
-g file - -
-True if file exists and is set-group-id. -
-h file - -
-True if file exists and is a symbolic link. -
-k file - -
-True if file exists and its -bit is set. -
-p file +

−t fd

 + + +

True if file descriptor fd is open and refers to +a terminal.

 +
+ +

−u file

+ +

True if file exists and +its set-user-id bit is set.

+ +

−w file

+ +

True if file exists and +is writable.

+ +

−x file

+ +

True if file exists and +is executable.

+ +

−G file

+ +

True if file exists and +is owned by the effective group id.

+ +

−L file

+ +

True if file exists and +is a symbolic link.

+ +

−N file

+ +

True if file exists and +has been modified since it was last accessed.

+ +

−O file

+ +

True if file exists and +is owned by the effective user id.

-
-True if file exists and is a named pipe (FIFO). -
-r file +

−S file

-
-True if file exists and is readable. -
-s file +

True if file exists and +is a socket.

-
-True if file exists and has a size greater than zero. -
-t fd +

−o +optname

-
-True if file descriptor -fd +

True if the shell option +optname is enabled. See the list of options under the +description of the −o option to the set +builtin below.

-is open and refers to a terminal. -
-u file +

−v +varname

-
-True if file exists and its set-user-id bit is set. -
-w file - -
-True if file exists and is writable. -
-x file +

True if the shell variable +varname is set (has been assigned a value). If +varname is an indexed array variable name subscripted +by @ or *, this returns true if the array has +any set elements. If varname is an associative array +variable name subscripted by @ or *, this +returns true if an element with that key is set.

-
-True if file exists and is executable. -
-G file +

−R +varname

-
-True if file exists and is owned by the effective group id. -
-L file +

True if the shell variable +varname is set and is a name reference.

-
-True if file exists and is a symbolic link. -
-N file +

−z +string

-
-True if file exists and has been modified since it was last -accessed. -
-O file - -
-True if file exists and is owned by the effective user id. -
-S file +

True if the length of +string is zero.

-
-True if file exists and is a socket. -
-o optname + + + + + +
-
-True if the shell option -optname -is enabled. -See the list of options under the description of the --o +

string

 +
-option to the -set - -builtin below. -
-v varname +

−n +string

-
-True if the shell variable -varname +

True if the length of +string is non-zero.

-is set (has been assigned a value). -If varname is an indexed -array variable name subscripted by @ or *, -this returns true if the array has any set elements. -If varname is an associative -array variable name subscripted by @ or *, -this returns true if an element with that key is set. -
-R varname - -
-True if the shell variable -varname - -is set and is a name reference. -
-z string +

string1 == +string2
+string1 = string2

-
-True if the length of string is zero. -
string
-
-n string - -
-True if the length of -string - -is non-zero. +

True if the strings are equal. += should be used with the test command for +POSIX conformance. When used with the +[[ command, this performs pattern matching as +described above (Compound Commands).

-
string1 == string2
- -
string1 = string2
-True if the strings are equal. -= should be used with the test command for -POSIX -conformance. -When used with the [[ command, this performs pattern matching as -described above (Compound Commands). -
string1 != string2
-True if the strings are not equal. -
string1 < string2
-True if string1 sorts before string2 lexicographically. -
string1 > string2
-True if string1 sorts after string2 lexicographically. - -
-
-file1 -ef file2 -True if file1 and file2 refer to the same device and -inode numbers. -
file1 -nt file2
-True if file1 is newer (according to modification date) than file2, -or if file1 exists and file2 does not. -
file1 -ot file2
-True if file1 is older than file2, or if file2 exists -and file1 does not. - -
arg1 OP arg2 - -
-OP - - -is one of --eq, - --ne, - --lt, - --le, - --gt, - -or --ge. - -These arithmetic binary operators return true if arg1 +

string1 != +string2

+ +

True if the strings are not +equal.

+ +

string1 < +string2

+ +

True if string1 sorts +before string2 lexicographically.

+ +

string1 > +string2

+ +

True if string1 sorts +after string2 lexicographically.

+ +

file1 −ef +file2

+ +

True if file1 and +file2 refer to the same device and inode numbers.

+ +

file1 −nt +file2

+ +

True if file1 is newer +(according to modification date) than file2, or if +file1 exists and file2 does not.

+ +

file1 −ot +file2

+ +

True if file1 is older +than file2, or if file2 exists and +file1 does not.

+ +

arg1 OP +arg2

+ +

OP is one +of −eq, −ne, −lt, +−le, −gt, or −ge. +These arithmetic binary operators return true if arg1 is equal to, not equal to, less than, less than or equal to, -greater than, or greater than or equal to arg2, respectively. -arg1 - -and -arg2 - -may be positive or negative integers. -When used with the [[ command, -arg1 - -and -arg2 - -are evaluated as arithmetic expressions (see -ARITHMETIC EVALUATION - - -above). -Since the expansions the [[ command performs on -arg1 - -and -arg2 - -can potentially result in empty strings, -arithmetic expression evaluation treats -those as expressions that evaluate to 0. - - -  -

SIMPLE COMMAND EXPANSION

- -When the shell executes a simple command, it performs the following -expansions, assignments, and redirections, from left to right, in -the following order. -
-
1.
-The words that the parser has marked as variable assignments (those -preceding the command name) and redirections are saved for later -processing. -
2.
-The words that are not variable assignments or redirections are -expanded. -If any words remain after expansion, the first word -is taken to be the name of the command and the remaining words are -the arguments. -
3.
-Redirections are performed as described above under -REDIRECTION. - - -
4.
-The text after the = in each variable assignment undergoes tilde -expansion, parameter expansion, command substitution, arithmetic expansion, -and quote removal before being assigned to the variable. -
-

- -If no command name results, the variable assignments affect the current -shell environment. -In the case of such a command (one that consists only of assignment -statements and redirections), assignment statements are performed before -redirections. -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 zero status. -  -

COMMAND EXECUTION

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

- -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 -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. -

- -If the name is neither a shell function nor a builtin, -and contains no slashes, -bash - -searches each element of the -PATH - - -for a directory containing an executable file by that name. -Bash - -uses a hash table to remember the full pathnames of executable -files (see -hash - -under -SHELL BUILTIN COMMANDS - - -below). -Bash performs a full search of the directories in -PATH - - -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 command_not_found_handle. -If that function exists, it is invoked in a separate execution environment -with the original command and -the original command's arguments as its arguments, and the function's -exit status becomes the exit status of that subshell. -If that function is not defined, the shell prints an error -message and returns an exit status of 127. -

- -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. -

- -If this execution fails because the file is not in executable +greater than, or greater than or equal to arg2, +respectively. arg1 and arg2 may be positive or +negative integers. When used with the [[ command, +arg1 and arg2 are evaluated as arithmetic +expressions (see ARITHMETIC EVALUATION +above). Since the expansions the [[ command performs +on arg1 and arg2 can potentially result in +empty strings, arithmetic expression evaluation treats those +as expressions that evaluate to 0.

+ +

SIMPLE COMMAND EXPANSION + +

+ + +

When the shell +executes a simple command, it performs the following +expansions, assignments, and redirections, from left to +right, in the following order.

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

1.

 + + +

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

+ + +

2.

 + + +

The words that are not variable assignments or +redirections are expanded. If any words remain after +expansion, the first word is taken to be the name of the +command and the remaining words are the arguments.

+ + +

3.

 + + +

Redirections are performed as described above under +REDIRECTION.

+ + +

4.

 + + +

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

+ +

If no command +name results, the variable assignments affect the current +shell environment. In the case of such a command (one that +consists only of assignment statements and redirections), +assignment statements are performed before redirections. +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 zero status.

+ +

COMMAND EXECUTION + +

+ + +

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

+ +

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 +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.

+ +

If the name is +neither a shell function nor a builtin, and contains no +slashes, bash searches each element of the +PATH for a directory containing an +executable file by that name. Bash uses a hash table +to remember the full pathnames of executable files (see +hash under SHELL BUILTIN +COMMANDS below). Bash performs a full search of +the directories in PATH 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 command_not_found_handle. If that +function exists, it is invoked in a separate execution +environment with the original command and the original +command’s arguments as its arguments, and the +function’s exit status becomes the exit status of that +subshell. If that function is not defined, the shell prints +an error message and returns an exit status of 127.

+ +

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.

+ +

If this +execution fails because the file is not in executable format, and the file is not a directory, it is assumed to be -a shell script, a file containing shell commands, -and the shell creates a new instance of itself to execute it. -Bash tries to determine whether the file is a text file or a binary, -and will not execute files it determines to be binaries. -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 -hash - -below under -SHELL BUILTIN COMMANDS - - -are retained by the child. -

- -If the program is a file beginning with -#!, - -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. -  -

COMMAND EXECUTION ENVIRONMENT

- -The shell has an execution environment, which consists of the -following: -
-
*
-Open files inherited by the shell at invocation, as modified by -redirections supplied to the exec builtin. -
*
-The current working directory as set by cd, pushd, or -popd, or inherited by the shell at invocation. -
*
-The file creation mode mask as set by umask or inherited from -the shell's parent. -
*
-Current traps set by trap. -
*
-Shell parameters that are set by variable assignment or with set -or inherited from the shell's parent in the environment. -
*
-Shell functions defined during execution or inherited from the shell's -parent in the environment. -
*
-Options enabled at invocation (either by default or with command-line -arguments) or by set. -
*
-Options enabled by shopt. -
*
-Shell aliases defined with alias. -
*
-Various process IDs, including those of background jobs, the value -of $$, and the value of -PPID. - - -
-

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

-
*
-The shell's open files, plus any modifications and additions specified -by redirections to the command. -
*
-The current working directory. -
*
-The file creation mode mask. -
*
-Shell variables and functions marked for export, along with variables -exported for the command, passed in the environment. -
*
-Traps caught by the shell are reset to the values inherited from the -shell's parent, and traps ignored by the shell are ignored. -
-

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

- -A subshell is a copy of the shell process. -

- -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, -except possibly in the last element depending on the value of the -lastpipe shell option, -are also executed in a subshell environment. -Changes made to the subshell environment -cannot affect the shell's execution environment. -

- -When the shell is in posix mode, -subshells spawned to execute command substitutions inherit the value of -the -e option from their parent shell. -When not in posix mode, -bash clears the -e option in such subshells. -See the -description of the inherit_errexit shell option below -for how to control this behavior when not in posix mode. -

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

ENVIRONMENT

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

- -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 -export - -to child processes. -Executed commands inherit the environment. -The -export, - -declare -x, - -and -unset - -commands modify the environment by -adding and deleting parameters and functions. -If the value of a parameter -in the environment is modified, the new value automatically -becomes part of the environment, replacing the old. -The environment -inherited by any executed command consists of the shell's -initial environment, whose values may be modified in the shell, -less any pairs removed by the -unset - -or -export -n - -commands, plus any additions via the -export - -and -declare -x - -commands. -

- -If any parameter assignments, as described above in -PARAMETERS, - - -appear before a -simple command, - -the variable assignments are part of that command's environment -for as long as it executes. -These assignment statements affect only the environment seen -by that command. -If these assignments precede a call to a shell function, the variables -are local to the function and exported to that function's children. -

- -If the --k - -option is set (see the -set - -builtin command below), then -all - -parameter assignments are placed in the environment for a command, -not just those that precede the command name. -

- -When -bash - -invokes an external command, the variable -_ - -is set to the full pathname of the command and passed to that -command in its environment. -  -

EXIT STATUS

- -The exit status of an executed command is the value returned by the -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. -So while an exit status of zero indicates success, a non-zero -exit status indicates failure. -

- -When a command terminates on a fatal signal N, bash uses -the value of 128+N as the exit status. -

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

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

- -Shell builtin commands return a status of 0 (true) if -successful, and non-zero (false) if an error occurs -while they execute. -All builtins return an exit status of 2 to indicate incorrect usage, -generally invalid options or missing arguments. -

- -The exit status of the last command is available in the special -parameter $?. -

- -Bash 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 exit builtin command below. -  -

SIGNALS

- -When bash is interactive, in the absence of any traps, it ignores -SIGTERM - - -(so that kill 0 does not kill an interactive shell), -and catches and handles -SIGINT - - -(so that the wait builtin is interruptible). -When bash receives -SIGINT, - - -it breaks out of any executing loops. -In all cases, bash ignores -SIGQUIT. - - -If job control is in effect, -bash - -ignores -SIGTTIN, - - -SIGTTOU, - - -and -SIGTSTP. - - -

- -The trap builtin modifies the shell's signal handling, as -described below. -

- -Non-builtin commands bash executes have signal handlers -set to the values inherited by the shell from its parent, -unless trap sets them to be ignored, in which case the child -process will ignore them as well. -When job control is not in effect, asynchronous commands -ignore -SIGINT - - -and -SIGQUIT - - -in addition to these inherited handlers. -Commands run as a result of command substitution ignore the -keyboard-generated job control signals -SIGTTIN, - - -SIGTTOU, - - -and -SIGTSTP. - - -

- -The shell exits by default upon receipt of a -SIGHUP. - - -Before exiting, an interactive shell resends the -SIGHUP - - -to all jobs, running or stopped. -The shell sends -SIGCONT - - -to stopped jobs to ensure that they receive the -SIGHUP - - -(see -JOB CONTROL - - -below for more information about running and stopped jobs). -To prevent the shell from -sending the signal to a particular job, remove it from the -jobs table with the -disown - -builtin (see -SHELL BUILTIN COMMANDS - - -below) or mark it not to receive -SIGHUP - - -using -disown -h. - -

- -If the -huponexit - -shell option has been set using -shopt, - -bash - -sends a -SIGHUP - - -to all jobs when an interactive login shell exits. -

- -If bash is waiting for a command to complete and receives a signal -for which a trap has been set, -it will not execute the trap until the command completes. -If bash is waiting for an asynchronous command via the wait -builtin, -and it receives a signal for which a trap has been set, -the wait builtin will return immediately with an exit status -greater than 128, immediately after which the shell executes the trap. -

- -When job control is not enabled, and bash is waiting for a foreground -command to complete, the shell receives keyboard-generated signals -such as -SIGINT - - -(usually generated by ^C) that users commonly intend to send -to that command. -This happens because the shell and the command are in the -same process group as the terminal, and ^C sends -SIGINT - - -to all processes in that process group. -Since bash does not enable job control by default when the -shell is not interactive, -this scenario is most common in non-interactive shells. -

- -When job control is enabled, and bash is waiting for a foreground -command to complete, the shell does not receive keyboard-generated -signals, because it is not in the same process group as the terminal. -This scenario is most common in interactive shells, where bash -attempts to enable job control by default. -See -JOB CONTROL - - -below for more information about process groups. -

- -When job control is not enabled, and bash receives -SIGINT - - -while waiting for a foreground command, it waits until that foreground -command terminates and then decides what to do about the -SIGINT: - - -

-
1.
-If the command terminates due to the -SIGINT, - - -bash concludes -that the user meant to send the -SIGINT - - -to the shell as well, and acts on the -SIGINT - - -(e.g., by running a -SIGINT - - -trap, -exiting a non-interactive shell, -or returning to the top level to read a new command). -
2.
-If the command does not terminate due to -SIGINT, - - -the program handled the -SIGINT - - -itself and did not treat it as a fatal signal. -In that case, bash does not treat -SIGINT - - -as a fatal signal, either, instead assuming that the -SIGINT - - -was used as part of the program's normal operation -(e.g., emacs uses it to abort editing -commands) or deliberately discarded. -However, bash will run any -trap set on -SIGINT, - - -as it does with any other trapped signal it -receives while it is waiting for the foreground command to -complete, for compatibility. -
-

- -When job control is enabled, bash does not receive keyboard-generated -signals such as -SIGINT - - -while it is waiting for a foreground command. -An interactive shell does not pay attention to the -SIGINT, - - -even if the foreground command terminates as a result, other than noting -its exit status. -If the shell is not interactive, and -the foreground command terminates due to the -SIGINT, - - -bash pretends it received the -SIGINT - - -itself (scenario 1 above), for compatibility. -  -

JOB CONTROL

- -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 -job - -with each pipeline. -It keeps a table of currently executing -jobs, which the -jobs - -command will display. -Each job has a job number, which jobs displays between brackets. -Job numbers start at 1. -When -bash - -starts a job asynchronously (in the -background), - -it prints a line that looks like: -

-

- -[1] 25647 -

- -

- -indicating that this job is job number 1 and that the process ID -of the last process in the pipeline associated with this job is 25647. -All of the processes in a single pipeline are members of the same job. -Bash - -uses the -job - -abstraction as the basis for job control. -

- -To facilitate the implementation of the user interface to job control, -each process has a process group ID, and -the operating system maintains the notion of a current terminal -process group ID. -This terminal process group ID is associated with the -controlling terminal. -

- -Processes that have the same process group ID are said to be part of -the same process group. -Members of the foreground process group (processes whose -process group ID is equal to the current terminal process group ID) -receive keyboard-generated signals such as -SIGINT. - - -Processes in the foreground process group are said to be -foreground - -processes. -Background - -processes are those whose process group ID differs from the -controlling 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 +a shell script, a file containing shell commands, and +the shell creates a new instance of itself to execute it. +Bash tries to determine whether the file is a text file or a +binary, and will not execute files it determines to be +binaries. 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 hash below under +SHELL BUILTIN COMMANDS are retained by +the child.

-write to the controlling terminal. -The system sends a -SIGTTIN (SIGTTOU) +

If the program +is a file beginning with #!, 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.

- -signal to background processes which attempt to -read from (write to when +

COMMAND EXECUTION ENVIRONMENT + +

-is in effect) -the terminal, -which, unless caught, suspends the process. -

-If the operating system on which -bash +

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

-is running supports -job control, -bash + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
-contains facilities to use it. -Typing the -suspend - -character (typically -^Z, - -Control-Z) while a process is running -stops that process and returns control to -bash. -Typing the -delayed suspend +

•

 -character (typically -^Y, -Control-Y) causes the process stop when it -attempts to read input from the terminal, and returns control to -bash. +

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

-The user then manipulates the state of this job, using the -bg -command to continue it in the background, the -fg +

•

 -command to continue it in the foreground, or the -kill -command to kill it. -The suspend character takes effect immediately, -and has the additional side effect of discarding any pending output -and typeahead. -To force a background process to stop, or stop a process -that's not associated with the current terminal session, -send it the -SIGSTOP +

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

- -signal using kill. -

-There are a number of ways to refer to a job in the shell. -The -% +

•

 -character introduces a job specification (jobspec). -

-Job number -n +

The file creation mode mask as set by umask or +inherited from the shell’s parent.

-may be referred to as -%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, -%ce +

•

 -refers to a job whose command name begins with -ce. -Using -%?ce, +

Current traps set by trap.

-on the other hand, refers to any job containing the string -ce -in its command line. -If the prefix or substring matches more than one job, -bash +

•

 -reports an error. -

-The symbols -%% +

Shell parameters that are set by variable assignment or +with set or inherited from the shell’s parent +in the environment.

-and -%+ -refer to the shell's notion of the -current job. - -A single % (with no accompanying job specification) also refers to the -current job. -%- +

•

 -refers to the -previous job. -When a job starts in the background, -a job stops while in the foreground, -or a job is resumed in the background, -it becomes the current job. -The job that was the current job becomes the previous job. -When the current job terminates, the previous job becomes the -current job. -If there is only a single job, %+ and %- can both be used -to refer to that job. -In output pertaining to jobs (e.g., the output of the -jobs +

Shell functions defined during execution or inherited +from the shell’s parent in the environment.

-command), the current job is always marked with a -+, - -and the previous job with a --. -

+

•

 -Simply naming a job can be used to bring it into the foreground: -%1 - -is a synonym for - -bringing job 1 from the background into the foreground. -Similarly, -resumes job 1 in the background, equivalent to +

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

-

- -The shell learns immediately whenever a job changes state. -Normally, -bash -waits until it is about to print a prompt before -notifying the user about -changes in a job's status so as to not interrupt -any other output, -though it will notify of changes in a job's status after a -foreground command in -a list completes, before executing the next command in the list. -If the --b +

•

 -option to the -set -builtin command -is enabled, -bash +

Options enabled by shopt.

-reports status changes immediately. -Bash executes any trap on -SIGCHLD - -for each child that terminates. -

+

•

 -When a job terminates and bash notifies the user about it, -bash removes the job from the table. -It will not appear in jobs output, but wait will -report its exit status, as long as it's supplied the process ID -associated with the job as an argument. -When the table is empty, job numbers start over at 1. -

-If a user attempts to exit -bash +

Shell aliases defined with alias.

-while jobs are stopped (or, if the checkjobs shell option has -been enabled using the shopt builtin, running), the shell prints a -warning message, and, if the checkjobs option is enabled, lists the -jobs and their statuses. -The -jobs -command may then be used to inspect their status. -If the user immediately attempts to exit again, -without an intervening command, -bash does not print another warning, and -terminates any stopped jobs. -

+

•

 -When the shell is waiting for a job or process using the wait -builtin, and job control is enabled, wait will return when the -job changes state. -The -f option causes wait to wait -until the job or process terminates before returning. -  -

PROMPTING

-When executing interactively, -bash +

Various process IDs, including those of background jobs, +the value of $$, and the value of +PPID.

-displays the primary prompt -PS1 +

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.

- -when it is ready to read a command, and the secondary prompt -PS2 + + + + + + + + + + + + + + + + + + + + + + + + + + +
- -when it needs more input to complete a command. -

-Bash +

•

 -examines the value of the array variable PROMPT_COMMAND just before -printing each primary prompt. -If any elements in PROMPT_COMMAND are set and non-null, Bash -executes each value, in numeric order, -just as if it had been typed on the command line. -Bash -displays -PS0 +

The shell’s open files, +plus any modifications and additions specified by +redirections to the command.

- -after it reads a command but before executing it. -

-Bash +

•

 -displays -PS4 - -as described above -before tracing each command when the -x option is enabled. -

- -Bash +

The current working directory.

-allows the prompt strings -PS0, PS1, PS2, and PS4, -to be customized by inserting a number of -backslash-escaped special characters that are decoded as follows: -
-
-
\a -
-An ASCII bell character (07). +

•

 -
\d -
-The date in +

The file creation mode mask.

-format (e.g., -
\D{format} +

•

 -
-The format is passed to -strftime(3) -and the result is inserted -into the prompt string; an empty format results in a locale-specific -time representation. -The braces are required. -
\e +

Shell variables and functions marked for export, along +with variables exported for the command, passed in the +environment.

+ + +

•

 + + +

Traps caught by the shell are reset to the values +inherited from the shell’s parent, and traps ignored +by the shell are ignored.

+ +

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

+ +

A +subshell is a copy of the shell process.

+ +

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, except +possibly in the last element depending on the value of the +lastpipe shell option, are also executed in a +subshell environment. Changes made to the subshell +environment cannot affect the shell’s execution +environment.

+ +

When the shell +is in posix mode, subshells spawned to execute command +substitutions inherit the value of the −e +option from their parent shell. When not in posix mode, +bash clears the −e option in such +subshells. See the description of the inherit_errexit +shell option below for how to control this behavior when not +in posix mode.

+ +

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

+ +

ENVIRONMENT + +

+ + +

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

+ +

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 export to child processes. Executed commands +inherit the environment. The export, declare +−x, and unset commands modify the +environment by adding and deleting parameters and functions. +If the value of a parameter in the environment is modified, +the new value automatically becomes part of the environment, +replacing the old. The environment inherited by any executed +command consists of the shell’s initial environment, +whose values may be modified in the shell, less any pairs +removed by the unset or export −n +commands, plus any additions via the export and +declare −x commands.

+ +

If any parameter +assignments, as described above in +PARAMETERS, appear +before a simple command, the variable assignments are +part of that command’s environment for as long as it +executes. These assignment statements affect only the +environment seen by that command. If these assignments +precede a call to a shell function, the variables are local +to the function and exported to that function’s +children.

+ +

If the +−k option is set (see the set builtin +command below), then all parameter assignments are +placed in the environment for a command, not just those that +precede the command name.

+ +

When bash +invokes an external command, the variable _ is set to +the full pathname of the command and passed to that command +in its environment.

+ +

EXIT STATUS + +

+ + +

The exit status +of an executed command is the value returned by the +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. So while an exit status of zero +indicates success, a non-zero exit status indicates +failure.

+ +

When a command +terminates on a fatal signal N, bash uses the +value of 128+N as the exit status.

+ +

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

+ +

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

+ +

Shell builtin +commands return a status of 0 (true) if successful, +and non-zero (false) if an error occurs while they +execute. All builtins return an exit status of 2 to indicate +incorrect usage, generally invalid options or missing +arguments.

+ +

The exit status +of the last command is available in the special parameter +$?.

+ +

Bash +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 exit builtin command +below.

+ +

SIGNALS + +

+ + +

When bash +is interactive, in the absence of any traps, it ignores +SIGTERM (so that kill 0 does +not kill an interactive shell), and catches and handles +SIGINT (so that the wait +builtin is interruptible). When bash receives +SIGINT, it breaks out +of any executing loops. In all cases, bash ignores +SIGQUIT. If job control +is in effect, bash ignores +SIGTTIN, +SIGTTOU, and +SIGTSTP.

+ +

The trap +builtin modifies the shell’s signal handling, as +described below.

+ +

Non-builtin +commands bash executes have signal handlers set to +the values inherited by the shell from its parent, unless +trap sets them to be ignored, in which case the child +process will ignore them as well. When job control is not in +effect, asynchronous commands ignore +SIGINT and +SIGQUIT in addition to these inherited +handlers. Commands run as a result of command substitution +ignore the keyboard-generated job control signals +SIGTTIN, +SIGTTOU, and +SIGTSTP.

+ +

The shell exits +by default upon receipt of a +SIGHUP. Before exiting, +an interactive shell resends the +SIGHUP to all jobs, running or +stopped. The shell sends SIGCONT to +stopped jobs to ensure that they receive the +SIGHUP (see JOB +CONTROL below for more information about running +and stopped jobs). To prevent the shell from sending the +signal to a particular job, remove it from the jobs table +with the disown builtin (see SHELL BUILTIN +COMMANDS below) or mark it not to receive +SIGHUP using disown +−h.

+ +

If the +huponexit shell option has been set using +shopt, bash sends a +SIGHUP to all jobs when an interactive +login shell exits.

+ +

If bash +is waiting for a command to complete and receives a signal +for which a trap has been set, it will not execute the trap +until the command completes. If bash is waiting for +an asynchronous command via the wait builtin, and it +receives a signal for which a trap has been set, the +wait builtin will return immediately with an exit +status greater than 128, immediately after which the shell +executes the trap.

+ +

When job control +is not enabled, and bash is waiting for a foreground +command to complete, the shell receives keyboard-generated +signals such as SIGINT (usually +generated by ^C) that users commonly intend to send +to that command. This happens because the shell and the +command are in the same process group as the terminal, and +^C sends SIGINT to all +processes in that process group. Since bash does not +enable job control by default when the shell is not +interactive, this scenario is most common in non-interactive +shells.

+ +

When job control +is enabled, and bash is waiting for a foreground +command to complete, the shell does not receive +keyboard-generated signals, because it is not in the same +process group as the terminal. This scenario is most common +in interactive shells, where bash attempts to enable +job control by default. See JOB +CONTROL below for more information about process +groups.

+ +

When job control +is not enabled, and bash receives +SIGINT while waiting for a foreground +command, it waits until that foreground command terminates +and then decides what to do about the +SIGINT:

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

1.

 + + +

If the command terminates due to +the SIGINT, bash +concludes that the user meant to send the +SIGINT to the shell as well, and acts +on the SIGINT (e.g., by running a +SIGINT trap, exiting a non-interactive +shell, or returning to the top level to read a new +command).

+ + +

2.

 + + +

If the command does not terminate due to +SIGINT, the program +handled the SIGINT itself and did not +treat it as a fatal signal. In that case, bash does +not treat SIGINT as a fatal signal, +either, instead assuming that the +SIGINT was used as part of the +program’s normal operation (e.g., emacs uses it to +abort editing commands) or deliberately discarded. However, +bash will run any trap set on +SIGINT, as it does with +any other trapped signal it receives while it is waiting for +the foreground command to complete, for compatibility.

+ +

When job control +is enabled, bash does not receive keyboard-generated +signals such as SIGINT while it is +waiting for a foreground command. An interactive shell does +not pay attention to the +SIGINT, even if the +foreground command terminates as a result, other than noting +its exit status. If the shell is not interactive, and the +foreground command terminates due to the +SIGINT, bash +pretends it received the SIGINT itself +(scenario 1 above), for compatibility.

+ +

JOB CONTROL + +

+ + +

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 job with each pipeline. It keeps a table +of currently executing jobs, which the jobs command +will display. Each job has a job number, which +jobs displays between brackets. Job numbers start at +1. When bash starts a job asynchronously (in the +background), it prints a line that looks like:

+ +

[1] 25647

+ +

indicating that +this job is job number 1 and that the process ID of the last +process in the pipeline associated with this job is 25647. +All of the processes in a single pipeline are members of the +same job. Bash uses the job abstraction as the +basis for job control.

+ +

To facilitate +the implementation of the user interface to job control, +each process has a process group ID, and the +operating system maintains the notion of a current +terminal process group ID. This terminal process group +ID is associated with the controlling terminal.

+ +

Processes that +have the same process group ID are said to be part of the +same process group. Members of the foreground +process group (processes whose process group ID is equal to +the current terminal process group ID) receive +keyboard-generated signals such as +SIGINT. Processes in +the foreground process group are said to be +foreground processes. Background processes are +those whose process group ID differs from the controlling +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 +“stty tostop”, write to the controlling +terminal. The system sends a SIGTTIN +(SIGTTOU) signal to background processes which +attempt to read from (write to when “tostop” is +in effect) the terminal, which, unless caught, suspends the +process.

+ +

If the operating +system on which bash is running supports job control, +bash contains facilities to use it. Typing the +suspend character (typically ^Z, Control-Z) +while a process is running stops that process and returns +control to bash. Typing the delayed suspend +character (typically ^Y, Control-Y) causes the +process stop when it attempts to read input from the +terminal, and returns control to bash. The user then +manipulates the state of this job, using the bg +command to continue it in the background, the fg +command to continue it in the foreground, or the kill +command to kill it. The suspend character takes effect +immediately, and has the additional side effect of +discarding any pending output and typeahead. To force a +background process to stop, or stop a process that’s +not associated with the current terminal session, send it +the SIGSTOP signal using +kill.

+ +

There are a +number of ways to refer to a job in the shell. The % +character introduces a job specification (jobspec).

+ +

Job number +n may be referred to as %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, %ce refers to a job whose command name +begins with ce. Using %?ce, on the other hand, +refers to any job containing the string ce in its +command line. If the prefix or substring matches more than +one job, bash reports an error.

+ +

The symbols +%% and %+ refer to the shell’s notion of +the current job. A single % (with no accompanying job +specification) also refers to the current job. +%− refers to the previous job. When a +job starts in the background, a job stops while in the +foreground, or a job is resumed in the background, it +becomes the current job. The job that was the current job +becomes the previous job. When the current job terminates, +the previous job becomes the current job. If there is only a +single job, %+ and %− can both be used +to refer to that job. In output pertaining to jobs (e.g., +the output of the jobs command), the current job is +always marked with a +, and the previous job with a +−.

+ +

Simply naming a +job can be used to bring it into the foreground: %1 +is a synonym for “fg %1”, bringing job 1 from +the background into the foreground. Similarly, “%1 +&” resumes job 1 in the background, equivalent to +“bg %1”.

+ +

The shell learns +immediately whenever a job changes state. Normally, +bash waits until it is about to print a prompt before +notifying the user about changes in a job’s status so +as to not interrupt any other output, though it will notify +of changes in a job’s status after a foreground +command in a list completes, before executing the next +command in the list. If the −b option to the +set builtin command is enabled, bash reports +status changes immediately. Bash executes any trap on +SIGCHLD for each child that +terminates.

+ +

When a job +terminates and bash notifies the user about it, +bash removes the job from the table. It will not +appear in jobs output, but wait will report +its exit status, as long as it’s supplied the process +ID associated with the job as an argument. When the table is +empty, job numbers start over at 1.

+ +

If a user +attempts to exit bash while jobs are stopped (or, if +the checkjobs shell option has been enabled using the +shopt builtin, running), the shell prints a warning +message, and, if the checkjobs option is enabled, +lists the jobs and their statuses. The jobs command +may then be used to inspect their status. If the user +immediately attempts to exit again, without an intervening +command, bash does not print another warning, and +terminates any stopped jobs.

+ +

When the shell +is waiting for a job or process using the wait +builtin, and job control is enabled, wait will return +when the job changes state. The −f option +causes wait to wait until the job or process +terminates before returning.

+ +

PROMPTING + +

+ + +

When executing +interactively, bash displays the primary prompt +PS1 when it is ready to read a +command, and the secondary prompt PS2 +when it needs more input to complete a command.

+ +

Bash +examines the value of the array variable +PROMPT_COMMAND just before printing each primary +prompt. If any elements in PROMPT_COMMAND are set and +non-null, Bash executes each value, in numeric order, just +as if it had been typed on the command line. Bash +displays PS0 after it reads a command +but before executing it.

+ +

Bash +displays PS4 as described above before +tracing each command when the −x option is +enabled.

+ +

Bash +allows the prompt strings PS0, PS1, +PS2, and PS4, to be customized by inserting a +number of backslash-escaped special characters that are +decoded as follows:

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

\a

 -
-An ASCII escape character (033). -
\h -
-The hostname up to the first +

An ASCII bell character +(07).

-
\H -
-The hostname. -
\j +

\d

 -
-The number of jobs currently managed by the shell. -
\l -
-The basename of the shell's terminal device name (e.g., +

The date in “Weekday Month Date” format +(e.g., “Tue May 26”).

-
\n -
-A newline. -
\r +

\D{format}

-
-A carriage return. -
\s +

The format is passed to +strftime(3) and the result is inserted into the +prompt string; an empty format results in a +locale-specific time representation. The braces are +required.

-
-The name of the shell: the basename of -$0 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
-(the portion following the final slash). -
\t -
-The current time in 24-hour HH:MM:SS format. -
\T +

\e

 -
-The current time in 12-hour HH:MM:SS format. -
\@ -
-The current time in 12-hour am/pm format. -
\A +

An ASCII escape character (033).

-
-The current time in 24-hour HH:MM format. -
\u -
-The username of the current user. -
\v +

\h

 -
-The bash version (e.g., 2.00). -
\V -
-The bash release, version + patch level (e.g., 2.00.0) -
\w +

The hostname up to the first “.”.

-
-The value of the PWD shell variable ($PWD), -with -$HOME - -abbreviated with a tilde -(uses the value of the -PROMPT_DIRTRIM +

\H

 - -variable). -
\W -
-The basename of $PWD, -with -$HOME +

The hostname.

- -abbreviated with a tilde. -
\! -
-The history number of this command. -
\# +

\j

 -
-The command number of this command. -
\$ -
-If the effective UID is 0, a -#, +

The number of jobs currently managed by the shell.

-otherwise a -$. -
\nnn +

\l

 -
-The character corresponding to the octal number nnn. -
\\ -
-A backslash. -
\[ +

The basename of the shell’s terminal device name +(e.g., “ttys0”).

-
-Begin a sequence of non-printing characters, which could be used to -embed a terminal control sequence into the prompt. -
\] -
-End a sequence of non-printing characters. +

\n

 - -

+

A newline.

-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 -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 -promptvars +

\r

 -shell option (see the description of the -shopt -command under -SHELL BUILTIN COMMANDS - - -below). -This can have unwanted side effects if escaped portions of the string -appear within command substitution or contain characters special to -word expansion. -  -

READLINE

- -This is the library that handles reading input when using an interactive -shell, unless the ---noediting - -option is supplied at shell invocation. -Line editing is also used when using the -e option to the -read 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 --o emacs - -or --o vi - -options to the -set - -builtin (see -SHELL BUILTIN COMMANDS - - -below). -To turn off line editing after the shell is running, use the -+o emacs - -or -+o vi - -options to the -set - -builtin. -  -

Readline Notation

- -This section uses Emacs-style editing concepts and uses its -notation for keystrokes. -Control keys are denoted by C-key, e.g., C-n means Control-N. -Similarly, -meta - -keys are denoted by M-key, so M-x means Meta-X. -The Meta key is often labeled - -or - -

- -On keyboards without a -Meta - -key, M-x means ESC x, -i.e., press and release the Escape key, -then press and release the -x - -key, in sequence. -This makes ESC the meta prefix. -The combination M-C-x means ESC Control-x: -press and release the Escape key, -then press and hold the Control key while pressing the -x - -key, then release both. -

- -On some keyboards, the Meta key modifier produces characters with -the eighth bit (0200) set. -You can use the enable-meta-key variable -to control whether or not it does this, if the keyboard allows it. -On many others, the terminal or terminal emulator converts the metafied -key to a key sequence beginning with ESC as described in the -preceding paragraph. -

- -If your Meta key produces a key sequence with the ESC meta prefix, -you can make M-key key bindings you specify (see -Readline Key Bindings - -below) do the same thing by setting the force-meta-prefix variable. -

- -Readline - -commands may be given numeric -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., kill-line) -makes that command act in a backward direction. -Commands whose behavior with arguments deviates from this are noted -below. -

+

A carriage return.

-The point is the current cursor position, and mark refers -to a saved cursor position. -The text between the point and mark is referred to as the region. -Readline has the concept of an active region: -when the region is active, readline redisplay -highlights the region using the -value of the active-region-start-color variable. -The enable-active-region variable turns this on and off. -Several commands set the region to active; those are noted below. -

-When a command is described as killing text, the text -deleted is saved for possible future retrieval -(yanking). -The killed text is saved in a kill ring. -Consecutive kills accumulate the deleted text -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. -  -

Readline Initialization

+

\s

 -Readline -is customized by putting commands in an initialization -file (the inputrc file). -The name of this file is taken from the value of the -INPUTRC +

The name of the shell: the basename of $0 (the +portion following the final slash).

- -shell variable. -If that variable is unset, the default is -~/.inputrc. +

\t

 -If that file does not exist or cannot be read, readline looks for -/etc/inputrc. +

The current time in 24-hour HH:MM:SS format.

-When a program that uses the readline library starts up, -readline reads the initialization file -and sets the key bindings and variables found there, -before reading any user input. -

-There are only a few basic constructs allowed in the inputrc file. -Blank lines are ignored. -Lines beginning with a # are comments. -Lines beginning with a $ indicate conditional constructs. -Other lines denote key bindings and variable settings. -

+

\T

 -The default key-bindings in this section -may be changed using key binding commands in the -inputrc -file. -Programs that use the readline library, including bash, -may add their own commands and bindings. -

+

The current time in 12-hour HH:MM:SS format.

-For example, placing -
-

-M-Control-u: universal-argument -

+

\@

 -or -
-C-Meta-u: universal-argument -
-

+

The current time in 12-hour am/pm format.

-into the -inputrc -would make M-C-u execute the readline command -universal-argument. +

\A

 -

-Key bindings may contain the following symbolic character names: -DEL, +

The current time in 24-hour HH:MM format.

-ESC, -ESCAPE, +

\u

 -LFD, -NEWLINE, +

The username of the current user.

-RET, -RETURN, +

\v

 -RUBOUT -(a destructive backspace), -SPACE, +

The bash version (e.g., 2.00).

-SPC, -and -TAB. +

\V

 -

-In addition to command names, readline allows keys to be bound -to a string that is inserted when the key is pressed (a macro). -The difference between a macro and a command is that a macro is -enclosed in single or double quotes. -  -

Readline Key Bindings

+

The bash release, version + patch level (e.g., +2.00.0)

-The syntax for controlling key bindings in the -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 key sequence may be specified in one of two ways: -as a symbolic key name, -possibly with Meta- or Control- prefixes, -or as a key sequence composed of one or more characters -enclosed in double quotes. -The key sequence and name are separated by a colon. -There can be no whitespace between the name and the colon. -

+

\w

 -When using the form keyname:function-name or macro, -keyname -is the name of a key spelled out in English. For example: -

+

The value of the PWD shell variable +($PWD), with $HOME abbreviated +with a tilde (uses the value of the +PROMPT_DIRTRIM variable).

-
-
-Control-u: universal-argument
-Meta-Rubout: backward-kill-word
-Control-o: "
-> output"
+
\W
 - +

The basename of $PWD, with +$HOME abbreviated with a tilde.

- -

+

\!

 -In the above example, -C-u -is bound to the function -universal-argument, +

The history number of this command.

-M-DEL -is bound to the function -backward-kill-word, +

\#

 -and -C-o -is bound to run the macro -expressed on the right hand side (that is, to insert the text +

The command number of this command.

-into the line). -

-In the second form, -" -keyseq" -:function-name or macro, -keyseq +

\$

 -differs from -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 none of -the symbolic character names are recognized. -

+

If the effective UID is 0, a #, otherwise a +$.

-
-
-"
-\C-u"
-: universal-argument
-"
-\C-x\C-r"
-: re-read-init-file
-"
-\e[11~"
-: "
-Function Key 1"
+
\nnn
 - +

The character corresponding to the octal number +nnn.

- -

+

\\

 -In this example, -C-u -is again bound to the function -universal-argument. +

A backslash.

-C-x C-r +

\[

 + + +

Begin a sequence of non-printing characters, which could +be used to embed a terminal control sequence into the +prompt.

+ + +

\]

 + + +

End a sequence of non-printing characters.

+ +

The command +number and the history number are usually different: the +history number of a command is its position in the history +list, which may include commands restored from the history +file (see 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 promptvars shell option +(see the description of the shopt command under +SHELL BUILTIN COMMANDS below). This +can have unwanted side effects if escaped portions of the +string appear within command substitution or contain +characters special to word expansion.

+ +

READLINE + +

+ + +

This is the +library that handles reading input when using an interactive +shell, unless the −−noediting option is +supplied at shell invocation. Line editing is also used when +using the −e option to the read 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 +−o emacs or −o vi options to the +set builtin (see SHELL BUILTIN +COMMANDS below). To turn off line editing after +the shell is running, use the +o emacs or +o +vi options to the set builtin.

+ +

Readline Notation + +

+ + +

This section +uses Emacs-style editing concepts and uses its notation for +keystrokes. Control keys are denoted by C−key, +e.g., C−n means Control−N. Similarly, +meta keys are denoted by M−key, so +M−x means Meta−X. The Meta key is often labeled +“Alt” or “Option”.

+ +

On keyboards +without a Meta key, M−x means ESC +x, i.e., press and release the Escape key, then press +and release the x key, in sequence. This makes ESC +the meta prefix. The combination +M−C−x means ESC Control−x: +press and release the Escape key, then press and hold the +Control key while pressing the x key, then release +both.

+ +

On some +keyboards, the Meta key modifier produces characters with +the eighth bit (0200) set. You can use the +enable−meta−key variable to control +whether or not it does this, if the keyboard allows it. On +many others, the terminal or terminal emulator converts the +metafied key to a key sequence beginning with ESC as +described in the preceding paragraph.

+ +

If your +Meta key produces a key sequence with the ESC meta +prefix, you can make M-key key bindings you specify +(see Readline Key Bindings below) do the same thing +by setting the force−meta−prefix +variable.

+ +

Readline +commands may be given numeric 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., kill−line) makes that command +act in a backward direction. Commands whose behavior with +arguments deviates from this are noted below.

+ +

The point +is the current cursor position, and mark refers to a +saved cursor position. The text between the point and mark +is referred to as the region. Readline has the +concept of an active region: when the region is +active, readline redisplay highlights the region +using the value of the active-region-start-color +variable. The enable−active−region +variable turns this on and off. Several commands set the +region to active; those are noted below.

+ +

When a command +is described as killing text, the text deleted is +saved for possible future retrieval (yanking). The +killed text is saved in a kill ring. Consecutive +kills accumulate the deleted text 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.

+ +

Readline Initialization + +

+ + +

Readline +is customized by putting commands in an initialization file +(the inputrc file). The name of this file is taken +from the value of the INPUTRC shell +variable. If that variable is unset, the default is +~/.inputrc. If that file does not exist or cannot be +read, readline looks for /etc/inputrc. When a +program that uses the readline library starts up, +readline reads the initialization file and sets the +key bindings and variables found there, before reading any +user input.

+ +

There are only a +few basic constructs allowed in the inputrc file. Blank +lines are ignored. Lines beginning with a # are +comments. Lines beginning with a $ indicate +conditional constructs. Other lines denote key bindings and +variable settings.

+ +

The default +key-bindings in this section may be changed using key +binding commands in the inputrc file. Programs that +use the readline library, including bash, may +add their own commands and bindings.

+ +

For example, +placing

+ + +

M−Control−u: +universal−argument

+ +

or

+ +

C−Meta−u: +universal−argument

+ +

into the +inputrc would make M−C−u execute the +readline command universal−argument.

+ +

Key bindings may +contain the following symbolic character names: DEL, +ESC, ESCAPE, LFD, NEWLINE, +RET, RETURN, RUBOUT (a destructive +backspace), SPACE, SPC, and TAB.

+ +

In addition to +command names, readline allows keys to be bound to a +string that is inserted when the key is pressed (a +macro). The difference between a macro and a command +is that a macro is enclosed in single or double quotes.

+ +

Readline Key Bindings + +

+ + +

The syntax for +controlling key bindings in the 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 key sequence may be specified in one of two ways: +as a symbolic key name, possibly with Meta− or +Control− prefixes, or as a key sequence +composed of one or more characters enclosed in double +quotes. The key sequence and name are separated by a colon. +There can be no whitespace between the name and the +colon.

+ +

When using the +form keyname:function−name or +macro, keyname is the name of a key spelled +out in English. For example:

+ +

Control-u: +universal−argument
+Meta-Rubout: backward−kill−word
+Control-o: "> output"

+ +

In the above +example, C−u is bound to the function +universal−argument, M−DEL is bound +to the function backward−kill−word, and +C−o is bound to run the macro expressed on the +right hand side (that is, to insert the text “> +output” into the line).

+ +

In the second +form, "keyseq":function−name +or macro, keyseq differs from 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 none of the symbolic character names are +recognized.

+ + +

"\C−u": +universal−argument
+"\C−x\C−r": +re−read−init−file
+"\e[11~": "Function Key 1"

+ +

In this example, +C−u is again bound to the function +universal−argument. C−x C−r is bound to the function -re-read-init-file, +re−read−init−file, and ESC [ 1 1 +~ is bound to insert the text “Function Key +1”.

+ +

The full set of +GNU Emacs style escape sequences available when specifying +key sequences is

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

\C−

 + + +

A control prefix.

+ + +

\M−

 + + +

Adding the meta prefix or converting the following +character to a meta character, as described below under +force-meta-prefix.

+ + +

\e

 + + +

An escape character.

-and -ESC [ 1 1 ~ -is bound to insert the text +

\\

 -

-The full set of GNU Emacs style escape sequences available when specifying -key sequences is -

+

Backslash.

-
-
\C- -
-A control prefix. -
\M- +

\"

 -
-Adding the meta prefix or converting the following character to a meta -character, as described below under force-meta-prefix. -
\e -
-An escape character. -
\\ +

Literal ", a double quote.

-
-Backslash. -
\ -
-Literal " -, a double quote. -
\' +

\'

 -
-Literal ', a single quote. - +

Literal ', a single quote.

-

+

In addition to +the GNU Emacs style escape sequences, a second set of +backslash escapes is available:

-In addition to the GNU Emacs style escape sequences, a second -set of backslash escapes is available: -
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
-
-
\a -
-alert (bell) -
\b +

\a

 -
-backspace -
\d -
-delete -
\f +

alert (bell)

-
-form feed -
\n -
-newline -
\r +

\b

 -
-carriage return -
\t -
-horizontal tab -
\v +

backspace

-
-vertical tab -
\nnn -
-The eight-bit character whose value is the octal value nnn -(one to three digits). -
\xHH +

\d

 -
-The eight-bit character whose value is the hexadecimal value HH -(one or two hex digits). - +

delete

-

-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. -The backslash escapes described above are expanded -in the macro body. -Backslash quotes any other character in the macro text, -including " - and '. -

+

\f

 -Bash -will display or modify the current readline key bindings with the -bind +

form feed

-builtin command. -The --o emacs -or --o vi +

\n

 -options to the -set -builtin -(see -SHELL BUILTIN COMMANDS +

newline

- -below) -change the editing mode during interactive use. -  -

Readline Variables

-Readline has variables that can be used to further customize its -behavior. -A variable may be set in the -inputrc +

\r

 -file with a statement of the form -
-

-set variable-name value -

- -or using the bind builtin command (see -SHELL BUILTIN COMMANDS - - -below). -

- -Except where noted, readline variables can take the values -On - -or -Off - -(without regard to case). -Unrecognized variable names are ignored. -When readline reads a variable value, empty or null values, - -(case-insensitive), and +

carriage return

-are equivalent to On. -All other values are equivalent to -Off. -

-The bind -V command lists the current readline variable names -and values (see -SHELL BUILTIN COMMANDS +

\t

 - -below). -

-The variables and their default values are: -

+

horizontal tab

-
-
active-region-start-color +

\v

 -
-A string variable that controls the text color and background when displaying -the text in the active region (see the description of -enable-active-region below). -This string must not take up any physical character positions on the display, -so it should consist only of terminal escape sequences. -It is output to the terminal before displaying the text in the active region. -This variable is reset to the default value whenever the terminal type changes. -The default value is the string that puts the terminal in standout mode, -as obtained from the terminal's terminfo description. -A sample value might be -
active-region-end-color - -
-A string variable that - -the effects of active-region-start-color -and restores - -terminal display appearance after displaying text in the active region. -This string must not take up any physical character positions on the display, -so it should consist only of terminal escape sequences. -It is output to the terminal after displaying the text in the active region. -This variable is reset to the default value whenever the terminal type changes. -The default value is the string that restores the terminal from standout mode, -as obtained from the terminal's terminfo description. -A sample value might be - -
bell-style (audible) - -
-Controls what happens when readline wants to ring the terminal bell. -If set to none, readline never rings the bell. -If set to visible, readline uses a visible bell if one is available. -If set to audible, readline attempts to ring the terminal's bell. -
bind-tty-special-chars (On) - -
-If set to On, readline attempts to bind -the control characters that are treated specially by the kernel's -terminal driver to their readline equivalents. -These override the default readline bindings described here. -Type - -at a bash prompt to see your current terminal settings, -including the special control characters (usually cchars). -This binding takes place on each call to readline, -so changes made by - -can take effect. -
blink-matching-paren (Off) - -
-If set to On, readline attempts to briefly move the cursor to an -opening parenthesis when a closing parenthesis is inserted. -
colored-completion-prefix (Off) - -
-If set to On, when listing completions, readline displays the -common prefix of the set of possible completions using a different color. -The color definitions are taken from the value of the LS_COLORS -environment variable. -If there is a color definition in $LS_COLORS for the custom suffix - -readline uses this color for -the common prefix instead of its default. -
colored-stats (Off) - -
-If set to On, readline displays possible completions using different -colors to indicate their file type. -The color definitions are taken from the value of the LS_COLORS -environment variable. - - - -
comment-begin ( - -
- -The string that the readline -insert-comment - -command inserts. -This command is bound to -M-# - -in emacs mode and to -# - -in vi command mode. -
completion-display-width (-1) - -
-The number of screen columns used to display possible matches -when performing completion. -The value is ignored if it is less than 0 or greater than the terminal -screen width. -A value of 0 causes matches to be displayed one per line. -The default value is -1. -
completion-ignore-case (Off) - -
-If set to On, readline performs filename matching and completion -in a case-insensitive fashion. -
completion-map-case (Off) - -
-If set to On, and completion-ignore-case is enabled, -readline - -treats hyphens (-) and underscores (_) as equivalent when -performing case-insensitive filename matching and completion. -
completion-prefix-display-length (0) - -
-The maximum -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, readline -replaces common prefixes longer than this value -with an ellipsis when displaying possible completions. -If a completion begins with a period, -and eadline is completing filenames, -it uses three underscores instead of an ellipsis. -
completion-query-items (100) - -
-This determines when the user is queried about viewing -the number of possible completions -generated by the possible-completions 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, -readline asks whether or not the user wishes to view them; -otherwise readline simply lists them on the terminal. -A zero value means readline should never ask; negative values are -treated as zero. -
convert-meta (On) - -
-If set to On, readline converts characters it reads -that have the eighth bit set to an ASCII key sequence by -clearing the eighth bit and prefixing it with an escape character -(converting the character to have the meta prefix). -The default is On, but readline sets it to Off -if the locale contains -characters whose encodings may include bytes with the eighth bit set. -This variable is dependent on the LC_CTYPE locale category, and -may change if the locale changes. -This variable also affects key bindings; see the description of -force-meta-prefix below. -
disable-completion (Off) - -
-If set to On, readline inhibits word completion. -Completion characters are inserted into the line as if they -had been mapped to self-insert. -
echo-control-characters (On) - -
-When set to On, on operating systems that indicate they support it, -readline echoes a character corresponding to a signal generated from the -keyboard. -
editing-mode (emacs) - -
-Controls whether readline uses a set of key bindings similar -to Emacs or vi. -editing-mode - -can be set to either -emacs - -or -vi. - -
emacs-mode-string (@) - -
-If the show-mode-in-prompt variable is enabled, -this string is displayed immediately before the last line of the -primary prompt when emacs editing mode is active. -The value is expanded like a -key binding, so the standard set of meta- and control- prefixes and -backslash escape sequences is available. -The \1 and \2 escapes begin and end sequences of -non-printing characters, which can be used to embed a terminal control -sequence into the mode string. -
enable-active-region (On) - -
-When this variable is set to On, readline allows certain commands -to designate the region as active. -When the region is active, readline -highlights the text in the region using the value of the -active-region-start-color - -variable, which defaults to the string that enables -the terminal's standout mode. -The active region shows the text inserted by bracketed-paste and any -matching text found by incremental and non-incremental history searches. -
enable-bracketed-paste (On) - -
-When set to On, readline configures the terminal to insert each -paste into the editing buffer as a single string of characters, instead -of treating each character as if it had been read from the keyboard. -This is called bracketed-paste mode; -it prevents readline from executing any editing commands bound to key -sequences appearing in the pasted text. -
enable-keypad (Off) - -
-When set to On, readline tries to enable the application -keypad when it is called. -Some systems need this to enable the arrow keys. -
enable-meta-key (On) - -
-When set to On, readline tries to enable any meta modifier -key the terminal claims to support. -On many terminals, the Meta key is used to send eight-bit characters; -this variable checks for the terminal capability that indicates the -terminal can enable and disable a mode that sets the eighth bit of a -character (0200) if the Meta key is held down when the character is -typed (a meta character). -
expand-tilde (Off) - -
-If set to On, readline performs tilde expansion when it -attempts word completion. -
force-meta-prefix (Off) - -
-If set to On, readline modifies its behavior when binding key -sequences containing \M- or Meta- -(see Key Bindings above) by converting a key sequence of the form -\M-C or Meta-C to the two-character sequence -ESC C (adding the meta prefix). -If -force-meta-prefix - -is set to Off (the default), -readline uses the value of the -convert-meta - -variable to determine whether to perform this conversion: -if convert-meta is On, -readline performs the conversion described above; -if it is Off, readline converts C to a meta character by -setting the eighth bit (0200). -
history-preserve-point (Off) - -
-If set to On, the history code attempts to place point at the -same location on each history line retrieved with previous-history -or next-history. -
history-size (unset) - -
-Set the maximum number of history entries saved in the history list. -If set to zero, any existing history entries are deleted and no new entries -are saved. -If set to a value less than zero, the number of history entries is not -limited. -By default, bash sets the maximum number of history entries to -the value of the HISTSIZE shell variable. -Setting history-size to a non-numeric value will set -the maximum number of history entries to 500. -
horizontal-scroll-mode (Off) - -
-Setting this variable to On 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. -This setting is automatically enabled for terminals of height 1. -
input-meta (Off) - -
-If set to On, readline enables eight-bit input (that is, it -does not clear the eighth bit in the characters it reads), -regardless of what the terminal claims it can support. -The default is Off, but readline sets it to On -if the locale contains characters whose encodings may include bytes -with the eighth bit set. -This variable is dependent on the LC_CTYPE locale category, and -its value may change if the locale changes. -The name meta-flag is a synonym for input-meta. -
isearch-terminators ( - -
- -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 -ESC and C-j terminate an incremental search. -
keymap (emacs) - -
-Set the current readline keymap. -The set of valid keymap names is -emacs, emacs-standard, emacs-meta, emacs-ctlx, vi, -vi-command, and -vi-insert. - -vi is equivalent to vi-command; -emacs is equivalent to emacs-standard. -The default value is emacs; -the value of -editing-mode - -also affects the default keymap. -
keyseq-timeout (500) - -
-Specifies the duration readline will wait for a character when -reading an ambiguous key sequence -(one that can form a complete key sequence using the input read so far, -or can take additional input to complete a longer key sequence). -If readline does not receive any input within the timeout, -it uses the shorter but complete key sequence. -The value is specified in milliseconds, so a value of 1000 means that -readline will wait one second for additional input. -If this variable is set to a value less than or equal to zero, or to a -non-numeric value, readline waits until another key is pressed to -decide which key sequence to complete. -
mark-directories (On) - -
-If set to On, completed directory names have a slash appended. -
mark-modified-lines (Off) - -
-If set to On, readline displays history lines -that have been modified -with a preceding asterisk (*). -
mark-symlinked-directories (Off) - -
-If set to On, completed names which are symbolic links to directories -have a slash appended, subject to the value of mark-directories. -
match-hidden-files (On) - -
-This variable, when set to On, forces readline to match files whose -names begin with a - -(hidden files) when performing filename completion. -If set to Off, the user must include the leading - -in the filename to be completed. -
menu-complete-display-prefix (Off) - -
-If set to On, menu completion displays the common prefix of the -list of possible completions (which may be empty) before cycling through -the list. -
output-meta (Off) - -
-If set to On, readline displays characters with the -eighth bit set directly rather than as a meta-prefixed escape -sequence. -The default is Off, but readline sets it to On -if the locale contains characters whose encodings may include -bytes with the eighth bit set. -This variable is dependent on the LC_CTYPE locale category, and -its value may change if the locale changes. -
page-completions (On) - -
-If set to On, readline uses an internal pager resembling -more(1) - -to display a screenful of possible completions at a time. -
prefer-visible-bell - -
-See bell-style. -
print-completions-horizontally (Off) - -
-If set to On, readline displays completions with matches -sorted horizontally in alphabetical order, rather than down the screen. -
revert-all-at-newline (Off) - -
-If set to On, readline will undo all changes to history lines -before returning when executing accept-line. -By default, -history lines may be modified and retain individual undo lists across -calls to readline. -
search-ignore-case (Off) - -
-If set to On, readline performs incremental and non-incremental -history list searches in a case-insensitive fashion. -
show-all-if-ambiguous (Off) - -
-This alters the default behavior of the completion functions. -If set to -On, +

vertical tab

+ +

\nnn

 + + +

The eight-bit character whose value is the octal value +nnn (one to three digits).

+ + +

\xHH

 + + +

The eight-bit character whose value is the hexadecimal +value HH (one or two hex digits).

+ +

When entering +the text of a macro, single or double quotes must be used to +indicate a macro definition. Unquoted text is assumed to be +a function name. The backslash escapes described above are +expanded in the macro body. Backslash quotes any other +character in the macro text, including " and '.

+ +

Bash will +display or modify the current readline key bindings +with the bind builtin command. The −o +emacs or −o vi options to the set +builtin (see SHELL BUILTIN COMMANDS +below) change the editing mode during interactive use.

+ +

Readline Variables + +

+ + +

Readline +has variables that can be used to further customize its +behavior. A variable may be set in the inputrc file +with a statement of the form

+ +

set +variable−name value

+ +

or using the bind builtin +command (see SHELL BUILTIN COMMANDS +below).

+ +

Except where +noted, readline variables can take the values +On or Off (without regard to case). +Unrecognized variable names are ignored. When +readline reads a variable value, empty or null +values, “on” (case-insensitive), and +“1” are equivalent to On. All other +values are equivalent to Off.

+ +

The bind +−V command lists the current readline +variable names and values (see SHELL BUILTIN +COMMANDS below).

+ +

The variables +and their default values are:
+active−region−start−color

+ +

A string variable that controls +the text color and background when displaying the text in +the active region (see the description of +enable−active−region below). This string +must not take up any physical character positions on the +display, so it should consist only of terminal escape +sequences. It is output to the terminal before displaying +the text in the active region. This variable is reset to the +default value whenever the terminal type changes. The +default value is the string that puts the terminal in +standout mode, as obtained from the terminal’s +terminfo description. A sample value might be +“\e[01;33m”.

+ + +

active−region−end−color

+ +

A string variable that +“undoes” the effects of +active−region−start−color and +restores “normal” terminal display appearance +after displaying text in the active region. This string must +not take up any physical character positions on the display, +so it should consist only of terminal escape sequences. It +is output to the terminal after displaying the text in the +active region. This variable is reset to the default value +whenever the terminal type changes. The default value is the +string that restores the terminal from standout mode, as +obtained from the terminal’s terminfo description. A +sample value might be “\e[0m”.

+ +

bell−style +(audible)

+ +

Controls what happens when +readline wants to ring the terminal bell. If set to +none, readline never rings the bell. If set to +visible, readline uses a visible bell if one +is available. If set to audible, readline +attempts to ring the terminal’s bell.

+ + +

bind−tty−special−chars +(On)

+ +

If set to On, +readline attempts to bind the control characters that +are treated specially by the kernel’s terminal driver +to their readline equivalents. These override the +default readline bindings described here. Type +“stty −a” at a bash prompt to see +your current terminal settings, including the special +control characters (usually cchars). This binding +takes place on each call to readline, so changes made +by “stty” can take effect.

+ + +

blink−matching−paren +(Off)

+ +

If set to On, +readline attempts to briefly move the cursor to an +opening parenthesis when a closing parenthesis is +inserted.

+ + +

colored−completion−prefix +(Off)

+ +

If set to On, when +listing completions, readline displays the common +prefix of the set of possible completions using a different +color. The color definitions are taken from the value of the +LS_COLORS environment variable. If there is a color +definition in $LS_COLORS for the custom suffix +“.readline-colored-completion-prefix”, +readline uses this color for the common prefix +instead of its default.

+ +

colored−stats +(Off)

+ +

If set to On, +readline displays possible completions using +different colors to indicate their file type. The color +definitions are taken from the value of the LS_COLORS +environment variable.

+ + +

comment−begin (“#”)

+ +

The string that the readline +insert−comment command inserts. This command is +bound to M−# in emacs mode and to # in +vi command mode.

+ + +

completion−display−width +(−1)

+ +

The number of screen columns +used to display possible matches when performing completion. +The value is ignored if it is less than 0 or greater than +the terminal screen width. A value of 0 causes matches to be +displayed one per line. The default value is −1.

+ + +

completion−ignore−case +(Off)

+ +

If set to On, +readline performs filename matching and completion in +a case−insensitive fashion.

+ + +

completion−map−case +(Off)

+ +

If set to On, and +completion−ignore−case is enabled, +readline treats hyphens (−) and +underscores (_) as equivalent when performing +case−insensitive filename matching and completion.

+ + +

completion−prefix−display−length +(0)

+ +

The maximum 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, readline replaces +common prefixes longer than this value with an ellipsis when +displaying possible completions. If a completion begins with +a period, and eadline is completing filenames, it +uses three underscores instead of an ellipsis.

+ + +

completion−query−items +(100)

+ +

This determines when the user +is queried about viewing the number of possible completions +generated by the possible−completions 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, readline asks +whether or not the user wishes to view them; otherwise +readline simply lists them on the terminal. A zero +value means readline should never ask; negative +values are treated as zero.

+ +

convert−meta +(On)

+ +

If set to On, +readline converts characters it reads that have the +eighth bit set to an ASCII key sequence by clearing the +eighth bit and prefixing it with an escape character +(converting the character to have the meta prefix). The +default is On, but readline sets it to +Off if the locale contains characters whose encodings +may include bytes with the eighth bit set. This variable is +dependent on the LC_CTYPE locale category, and may +change if the locale changes. This variable also affects key +bindings; see the description of +force−meta−prefix below.

+ +

disable−completion +(Off)

+ +

If set to On, +readline inhibits word completion. Completion +characters are inserted into the line as if they had been +mapped to self-insert.

+ + +

echo−control−characters +(On)

+ +

When set to On, on +operating systems that indicate they support it, +readline echoes a character corresponding to a signal +generated from the keyboard.

+ +

editing−mode +(emacs)

+ +

Controls whether +readline uses a set of key bindings similar to +Emacs or vi. editing−mode can be +set to either emacs or vi.

+ + +

emacs−mode−string +(@)

+ +

If the +show−mode−in−prompt variable is +enabled, this string is displayed immediately before the +last line of the primary prompt when emacs editing mode is +active. The value is expanded like a key binding, so the +standard set of meta- and control- prefixes and backslash +escape sequences is available. The \1 and \2 escapes begin +and end sequences of non-printing characters, which can be +used to embed a terminal control sequence into the mode +string.

+ + +

enable−active−region +(On)

+ +

When this variable is set to +On, readline allows certain commands to +designate the region as active. When the region is +active, readline highlights the text in the region +using the value of the +active−region−start−color variable, +which defaults to the string that enables the +terminal’s standout mode. The active region shows the +text inserted by bracketed-paste and any matching text found +by incremental and non-incremental history searches.

+ + +

enable−bracketed−paste +(On)

+ +

When set to On, +readline configures the terminal to insert each paste +into the editing buffer as a single string of characters, +instead of treating each character as if it had been read +from the keyboard. This is called bracketed−paste +mode; it prevents readline from executing any +editing commands bound to key sequences appearing in the +pasted text.

+ +

enable−keypad +(Off)

+ +

When set to On, +readline tries to enable the application keypad when +it is called. Some systems need this to enable the arrow +keys.

+ +

enable−meta−key +(On)

+ +

When set to On, +readline tries to enable any meta modifier key the +terminal claims to support. On many terminals, the Meta key +is used to send eight-bit characters; this variable checks +for the terminal capability that indicates the terminal can +enable and disable a mode that sets the eighth bit of a +character (0200) if the Meta key is held down when the +character is typed (a meta character).

+ +

expand−tilde +(Off)

+ +

If set to On, +readline performs tilde expansion when it attempts +word completion.

+ + +

force−meta−prefix +(Off)

+ +

If set to On, +readline modifies its behavior when binding key +sequences containing \M- or Meta- (see Key Bindings +above) by converting a key sequence of the form +\M−C or Meta−C to the +two-character sequence ESC C (adding the meta +prefix). If force−meta−prefix is set to +Off (the default), readline uses the value of +the convert−meta variable to determine whether +to perform this conversion: if convert−meta is +On, readline performs the conversion described +above; if it is Off, readline converts +C to a meta character by setting the eighth bit +(0200).

+ + +

history−preserve−point +(Off)

+ +

If set to On, the +history code attempts to place point at the same location on +each history line retrieved with previous-history or +next-history.

+ +

history−size +(unset)

+ +

Set the maximum number of +history entries saved in the history list. If set to zero, +any existing history entries are deleted and no new entries +are saved. If set to a value less than zero, the number of +history entries is not limited. By default, bash sets +the maximum number of history entries to the value of the +HISTSIZE shell variable. Setting +history−size to a non-numeric value will set +the maximum number of history entries to 500.

+ + +

horizontal−scroll−mode +(Off)

+ +

Setting this variable to +On 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. This setting is automatically +enabled for terminals of height 1.

+ +

input−meta +(Off)

+ +

If set to On, +readline enables eight-bit input (that is, it does +not clear the eighth bit in the characters it reads), +regardless of what the terminal claims it can support. The +default is Off, but readline sets it to +On if the locale contains characters whose encodings +may include bytes with the eighth bit set. This variable is +dependent on the LC_CTYPE locale category, and its +value may change if the locale changes. The name +meta−flag is a synonym for +input−meta.

+ + +

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 ESC and +C−j terminate an incremental search.

+ +

keymap (emacs)

+ +

Set the current readline +keymap. The set of valid keymap names is emacs, +emacs−standard, emacs−meta, emacs−ctlx, +vi, vi−command, and vi−insert. +vi is equivalent to vi−command; +emacs is equivalent to emacs−standard. +The default value is emacs; the value of +editing−mode also affects the default +keymap.

+ +

keyseq−timeout +(500)

+ +

Specifies the duration +readline will wait for a character when reading an +ambiguous key sequence (one that can form a complete key +sequence using the input read so far, or can take additional +input to complete a longer key sequence). If readline +does not receive any input within the timeout, it uses the +shorter but complete key sequence. The value is specified in +milliseconds, so a value of 1000 means that readline +will wait one second for additional input. If this variable +is set to a value less than or equal to zero, or to a +non-numeric value, readline waits until another key +is pressed to decide which key sequence to complete.

+ +

mark−directories +(On)

+ +

If set to On, completed +directory names have a slash appended.

+ + +

mark−modified−lines +(Off)

+ +

If set to On, +readline displays history lines that have been +modified with a preceding asterisk (*).

+ + +

mark−symlinked−directories +(Off)

+ +

If set to On, completed +names which are symbolic links to directories have a slash +appended, subject to the value of +mark−directories.

+ + +

match−hidden−files +(On)

+ +

This variable, when set to +On, forces readline to match files whose names +begin with a “.” (hidden files) when performing +filename completion. If set to Off, the user must +include the leading “.” in the filename to be +completed.

+ + +

menu−complete−display−prefix +(Off)

+ +

If set to On, menu +completion displays the common prefix of the list of +possible completions (which may be empty) before cycling +through the list.

+ +

output−meta +(Off)

+ +

If set to On, +readline displays characters with the eighth bit set +directly rather than as a meta-prefixed escape sequence. The +default is Off, but readline sets it to +On if the locale contains characters whose encodings +may include bytes with the eighth bit set. This variable is +dependent on the LC_CTYPE locale category, and its +value may change if the locale changes.

+ +

page−completions +(On)

+ +

If set to On, +readline uses an internal pager resembling +more(1) to display a screenful of possible +completions at a time.

+ + +

prefer−visible−bell

+ +

See +bell−style.

+ + +

print−completions−horizontally +(Off)

+ +

If set to On, +readline displays completions with matches sorted +horizontally in alphabetical order, rather than down the +screen.

+ + +

revert−all−at−newline +(Off)

+ +

If set to On, +readline will undo all changes to history lines +before returning when executing accept−line. By +default, history lines may be modified and retain individual +undo lists across calls to readline.

+ + +

search−ignore−case +(Off)

+ +

If set to On, +readline performs incremental and non-incremental +history list searches in a case−insensitive +fashion.

+ + +

show−all−if−ambiguous +(Off)

+ +

This alters the default +behavior of the completion functions. If set to On, words which have more than one possible completion cause the -matches to be listed immediately instead of ringing the bell. -

show-all-if-unmodified (Off) - -
-This alters the default behavior of the completion functions in -a fashion similar to show-all-if-ambiguous. -If set to -On, - -words which have more than one possible completion without any -possible partial completion (the possible completions don't share -a common prefix) cause the matches to be listed immediately instead -of ringing the bell. -
show-mode-in-prompt (Off) - -
-If set to On, add a string to the beginning of the prompt -indicating the editing mode: emacs, vi command, or vi insertion. -The mode strings are user-settable (e.g., emacs-mode-string). -
skip-completed-text (Off) - -
-If set to On, 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. -
vi-cmd-mode-string ((cmd)) - -
-If the show-mode-in-prompt variable is enabled, -this string is displayed immediately before the last line of the primary -prompt when vi editing mode is active and in command mode. -The value is expanded like a key binding, so the standard set of -meta- and control- prefixes and backslash escape sequences is available. -The \1 and \2 escapes begin and end sequences of -non-printing characters, which can be used to embed a terminal control -sequence into the mode string. -
vi-ins-mode-string ((ins)) - -
-If the show-mode-in-prompt variable is enabled, -this string is displayed immediately before the last line of the primary -prompt when vi editing mode is active and in insertion mode. -The value is expanded like a key binding, so the standard set of -meta- and control- prefixes and backslash escape sequences is available. -The \1 and \2 escapes begin and end sequences of -non-printing characters, which can be used to embed a terminal control -sequence into the mode string. -
visible-stats (Off) - -
-If set to On, a character denoting a file's type as reported -by stat(2) is appended to the filename when listing possible -completions. - -
-  -

Readline Conditional Constructs

- -Readline +matches to be listed immediately instead of ringing the +bell.

+ + +

show−all−if−unmodified +(Off)

+ +

This alters the default +behavior of the completion functions in a fashion similar to +show−all−if−ambiguous. If set to +On, words which have more than one possible +completion without any possible partial completion (the +possible completions don’t share a common prefix) +cause the matches to be listed immediately instead of +ringing the bell.

+ + +

show−mode−in−prompt +(Off)

+ +

If set to On, add a +string to the beginning of the prompt indicating the editing +mode: emacs, vi command, or vi insertion. The mode strings +are user-settable (e.g., +emacs−mode−string).

+ + +

skip−completed−text +(Off)

+ +

If set to On, 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.

+ + +

vi−cmd−mode−string +((cmd))

+

If the +show−mode−in−prompt variable is +enabled, this string is displayed immediately before the +last line of the primary prompt when vi editing mode is +active and in command mode. The value is expanded like a key +binding, so the standard set of meta- and control- prefixes +and backslash escape sequences is available. The \1 and \2 +escapes begin and end sequences of non-printing characters, +which can be used to embed a terminal control sequence into +the mode string.

+ + +

vi−ins−mode−string +((ins))

+ +

If the +show−mode−in−prompt variable is +enabled, this string is displayed immediately before the +last line of the primary prompt when vi editing mode is +active and in insertion mode. The value is expanded like a +key binding, so the standard set of meta- and control- +prefixes and backslash escape sequences is available. The \1 +and \2 escapes begin and end sequences of non-printing +characters, which can be used to embed a terminal control +sequence into the mode string.

+ +

visible−stats +(Off)

+ +

If set to On, a +character denoting a file’s type as reported by +stat(2) is appended to the filename when listing +possible completions.

+ +

Readline Conditional Constructs + +

+ + +

Readline implements a facility similar in spirit to the conditional compilation features of the C preprocessor which allows key bindings and variable settings to be performed as the result -of tests. -There are four parser directives available. -

-
$if - -
-The -$if - -construct allows bindings to be made based on the -editing mode, the terminal being used, or the application using -readline. -The text of the test, after any comparison operator, -extends to the end of the line; -unless otherwise noted, no characters are required to isolate it. -
-
-
mode - -
-The mode= form of the $if directive is used to test -whether readline is in emacs or vi mode. -This may be used in conjunction -with the set keymap command, for instance, to set bindings in -the emacs-standard and emacs-ctlx keymaps only if -readline is starting out in emacs mode. -
term - -
-The term= form may be used to include terminal-specific -key bindings, perhaps to bind the key sequences output by the -terminal's function keys. -The word on the right side of the -= - -is tested against both the full name of the terminal and the portion -of the terminal name before the first -. -This allows -xterm - -to match both -xterm - -and -xterm-256color, - -for instance. -
version - -
-The version test may be used to perform comparisons against -specific readline versions. -The version expands to the current readline version. -The set of comparison operators includes -=, - -(and -==), - -!=, - -<=, - ->=, - -<, - -and ->. - -The version number supplied on the right side of the operator consists -of a major version number, an optional decimal point, and an optional -minor version (e.g., 7.1). -If the minor version is omitted, it -defaults to 0. -The operator may be separated from the string version -and from the version number argument by whitespace. -
application - -
-The application construct is used to include -application-specific settings. -Each program using the readline -library sets the application name, 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 bash: -
-

- -

- -
-$if Bash
-# Quote the current or previous word
-"
-\C-xq"
-: "
-\eb\"
-\ef\"
-"
-
-$endif
-
- - -
- -
-
variable - -
-The variable construct provides simple equality tests for readline -variables and values. -The permitted comparison operators are =, ==, and !=. -The variable name must be separated from the comparison operator by -whitespace; the operator may be separated from the value on the right hand -side by whitespace. -String and boolean variables may be tested. -Boolean variables must be -tested against the values on and off. -
- -
$else - -
-Commands in this branch of the $if directive are executed if -the test fails. -
$endif - -
-This command, as seen in the previous example, terminates an -$if command. -
$include - -
-This directive takes a single filename as an argument and reads commands -and key bindings from that file. -For example, the following directive would read - -/etc/inputrc: - -
-

- -

-
-$include  /etc/inputrc
-
- -
- -  -

Searching

- -Readline - -provides commands for searching through the command history (see -HISTORY - - -below) -for lines containing a specified string. -There are two search modes: -incremental - -and -non-incremental. - -

- -Incremental searches begin before the user has finished typing the -search string. -As each character of the search string is typed, readline displays -the next entry from the history matching the string typed so far. -An incremental search requires only as many characters as needed to -find the desired history entry. -When using emacs editing mode, type C-r to -search backward in the history for a particular string. -Typing C-s searches forward through the history. -The characters present in the value of the isearch-terminators -variable are used to terminate an incremental search. -If that variable has not been assigned a value, -ESC and C-j terminate an incremental search. -C-g aborts an incremental search and restores the original line. -When the search is terminated, the history entry containing the -search string becomes the current line. -

- -To find other matching entries in the history list, type C-r or -C-s as appropriate. -This searches 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 terminates -the search and executes that command. -For instance, a newline terminates the search and accepts -the line, thereby executing the command from the history list. -A movement command will terminate the search, make the last line found -the current line, and begin editing. -

- -Readline - -remembers the last incremental search string. -If two C-rs are typed without any intervening characters defining -a new search string, readline uses any remembered search string. -

- -Non-incremental searches read the entire search string before starting -to search for matching history entries. -The search string may be -typed by the user or be part of the contents of the current line. -  -

Readline Command Names

- -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, point refers to the current cursor -position, and mark refers to a cursor position saved by the -set-mark command. -The text between the point and mark is referred to as the region. -Readline - -has the concept of an active region: -when the region is active, readline redisplay +of tests. There are four parser directives available.

+ + + + + + + +
+ + +

$if

 + + +

The $if construct allows bindings to be made +based on the editing mode, the terminal being used, or the +application using readline. The text of the test, +after any comparison operator, extends to the end of the +line; unless otherwise noted, no characters are required to +isolate it.

+ +

mode

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

The mode= form of the +$if directive is used to test whether readline +is in emacs or vi mode. This may be used in conjunction with +the set keymap command, for instance, to set bindings +in the emacs−standard and +emacs−ctlx keymaps only if readline is +starting out in emacs mode.

+ + +

term

 + + +

The term= form may be used to include +terminal-specific key bindings, perhaps to bind the key +sequences output by the terminal’s function keys. The +word on the right side of the = is tested against +both the full name of the terminal and the portion of the +terminal name before the first −. This allows +xterm to match both xterm and +xterm−256color, for instance.

+ +

version

+ +

The version test may be +used to perform comparisons against specific readline +versions. The version expands to the current +readline version. The set of comparison operators +includes =, (and ==), !=, <=, +>=, <, and >. The version +number supplied on the right side of the operator consists +of a major version number, an optional decimal point, and an +optional minor version (e.g., 7.1). If the minor +version is omitted, it defaults to 0. The operator +may be separated from the string version and from the +version number argument by whitespace.

+ +

application

+ +

The application +construct is used to include application-specific settings. +Each program using the readline library sets the +application name, 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 bash:

+ +

$if Bash +
+# Quote the current or previous word
+"\C-xq": "\eb\"\ef\""
+$endif

+ +

variable

+ +

The variable construct +provides simple equality tests for readline variables +and values. The permitted comparison operators are =, +==, and !=. The variable name must be +separated from the comparison operator by whitespace; the +operator may be separated from the value on the right hand +side by whitespace. String and boolean variables may be +tested. Boolean variables must be tested against the values +on and off.

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

$else

 + + +

Commands in this branch of the $if directive are +executed if the test fails.

+ + +

$endif

 + + +

This command, as seen in the previous example, +terminates an $if command.

+ +

$include

+ +

This directive takes a single +filename as an argument and reads commands and key bindings +from that file. For example, the following directive would +read /etc/inputrc:

+ + +

$include +/etc/inputrc

+ +

Searching + +

+ + + +

Readline +provides commands for searching through the command history +(see HISTORY below) for lines +containing a specified string. There are two search modes: +incremental and non-incremental.

+ +

Incremental +searches begin before the user has finished typing the +search string. As each character of the search string is +typed, readline displays the next entry from the +history matching the string typed so far. An incremental +search requires only as many characters as needed to find +the desired history entry. When using emacs editing mode, +type C−r to search backward in the history for +a particular string. Typing C−s searches +forward through the history. The characters present in the +value of the isearch-terminators variable are used to +terminate an incremental search. If that variable has not +been assigned a value, ESC and C−j +terminate an incremental search. C−g aborts an +incremental search and restores the original line. When the +search is terminated, the history entry containing the +search string becomes the current line.

+ +

To find other +matching entries in the history list, type C−r +or C−s as appropriate. This searches 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 terminates the search and executes +that command. For instance, a newline terminates the search +and accepts the line, thereby executing the command from the +history list. A movement command will terminate the search, +make the last line found the current line, and begin +editing.

+ +

Readline +remembers the last incremental search string. If two +C−rs are typed without any intervening +characters defining a new search string, readline +uses any remembered search string.

+ +

Non-incremental +searches read the entire search string before starting to +search for matching history entries. The search string may +be typed by the user or be part of the contents of the +current line.

+ +

Readline Command Names + +

+ + +

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, point refers to the current cursor +position, and mark refers to a cursor position saved +by the set−mark command. The text between the +point and mark is referred to as the region. +Readline has the concept of an active region: +when the region is active, readline redisplay highlights the region using the value of the -active-region-start-color - -variable. -The enable-active-region readline variable turns this on and off. -Several commands set the region to active; those are noted below. -  -

Commands for Moving

- - -
-
beginning-of-line (C-a) - -
-Move to the start of the current line. -This may also be bound to the Home key on some keyboards. -
end-of-line (C-e) - -
-Move to the end of the line. -This may also be bound to the End key on some keyboards. -
forward-char (C-f) - -
-Move forward a character. -This may also be bound to the right arrow key on some keyboards. -
backward-char (C-b) - -
-Move back a character. -This may also be bound to the left arrow key on some keyboards. -
forward-word (M-f) - -
-Move forward to the end of the next word. -Words are composed of alphanumeric characters (letters and digits). -
backward-word (M-b) - -
-Move back to the start of the current or previous word. -Words are composed of alphanumeric characters (letters and digits). -
shell-forward-word (M-C-f) - -
-Move forward to the end of the next word. -Words are delimited by non-quoted shell metacharacters. -
shell-backward-word (M-C-b) - -
-Move back to the start of the current or previous word. -Words are delimited by non-quoted shell metacharacters. -
previous-screen-line - -
-Attempt to move point to the same physical screen column on the previous -physical screen line. -This will not have the desired effect if the current -readline line does not take up more than one physical line or if -point is not greater than the length of the prompt plus the screen width. -
next-screen-line - -
-Attempt to move point to the same physical screen column on the next -physical screen line. -This will not have the desired effect if the current -readline line does not take up more than one physical line or if -the length of the current readline line is -not greater than the length of the prompt -plus the screen width. -
clear-display (M-C-l) - -
-Clear the screen and, if possible, the terminal's scrollback buffer, -then redraw the current line, -leaving the current line at the top of the screen. -
clear-screen (C-l) - -
-Clear the screen, -then redraw the current line, -leaving the current line at the top of the screen. -With a numeric argument, refresh the current line without clearing the -screen. -
redraw-current-line - -
-Refresh the current line. - -
-  -

Commands for Manipulating the History

- - -
-
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 -HISTCONTROL - - -and -HISTIGNORE - -variables. -If the line is a modified history line, -restore the history line to its original state. -
previous-history (C-p) - -
-Fetch the previous command from the history list, moving back in -the list. -This may also be bound to the up arrow key on some keyboards. -
next-history (C-n) - -
-Fetch the next command from the history list, moving forward in the -list. -This may also be bound to the down arrow key on some keyboards. -
beginning-of-history (M-<) - -
-Move to the first line in the history. -
end-of-history (M->) - -
-Move to the end of the input history, i.e., the line currently being -entered. -
operate-and-get-next (C-o) - -
-Accept the current line for execution as if a -newline had been entered, -and fetch the next line relative to the current line from the history -for editing. -A numeric argument, if supplied, specifies the history entry to use instead -of the current line. -
fetch-history - -
-With a numeric argument, fetch that entry from the history list -and make it the current line. -Without an argument, move back to the first entry in the history list. -
reverse-search-history (C-r) - -
-Search backward starting at the current line and moving - -through the history as necessary. -This is an incremental search. -This command sets the region to the matched text and activates the region. -
forward-search-history (C-s) - -
-Search forward starting at the current line and moving - -through the history as necessary. -This is an incremental search. -This command sets the region to the matched text and activates the region. -
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. -The search string may match anywhere in a history line. -
non-incremental-forward-search-history (M-n) - -
-Search forward through the history using a non-incremental search -for a string supplied by the user. -The search string may match anywhere in a history line. -
history-search-backward - -
-Search backward through the history for the string of characters -between the start of the current line and the point. -The search string must match at the beginning of a history line. -This is a non-incremental search. -This may be bound to the Page Up key on some keyboards. -
history-search-forward - -
-Search forward through the history for the string of characters -between the start of the current line and the point. -The search string must match at the beginning of a history line. -This is a non-incremental search. -This may be bound to the Page Down key on some keyboards. -
history-substring-search-backward - -
-Search backward through the history for the string of characters -between the start of the current line and the point. -The search string may match anywhere in a history line. -This is a non-incremental search. -
history-substring-search-forward - -
-Search forward through the history for the string of characters -between the start of the current line and the point. -The search string may match anywhere in a history line. -This is a non-incremental search. -
yank-nth-arg (M-C-y) - -
-Insert the first argument to the previous command (usually -the second word on the previous line) at point. -With an argument -n, - -insert the nth word from the previous command (the words -in the previous command begin with word 0). -A negative argument inserts the nth word from the end of -the previous command. -Once the argument n is computed, -this uses the history expansion facilities to extract the -nth word, as if the - -history expansion had been specified. -
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 yank-nth-arg. -Successive calls to yank-last-arg 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). -This uses the history expansion facilities to extract the -last word, as if the - -history expansion had been specified. -
shell-expand-line (M-C-e) - -
-Expand the line by performing shell word expansions. -This performs alias and history expansion, -$'string' and $" -string" - quoting, -tilde expansion, parameter and variable expansion, arithmetic expansion, -command and process substitution, -word splitting, and quote removal. -An explicit argument suppresses command and process substitution. -See -HISTORY EXPANSION - - -below for a description of history expansion. -
history-expand-line (M-^) - -
-Perform history expansion on the current line. -See -HISTORY EXPANSION - - -below for a description of history expansion. -
magic-space - -
-Perform history expansion on the current line and insert a space. -See -HISTORY EXPANSION - - -below for a description of history expansion. -
alias-expand-line - -
-Perform alias expansion on the current line. -See -ALIASES - - -above for a description of alias expansion. -
history-and-alias-expand-line - -
-Perform history and alias expansion on the current line. -
insert-last-argument (M-., M-_) - -
-A synonym for yank-last-arg. -
edit-and-execute-command (C-x C-e) - -
-Invoke an editor on the current command line, and execute the result as shell -commands. -Bash attempts to invoke -$VISUAL, - - -$EDITOR, - - -and emacs as the editor, in that order. - -
-  -

Commands for Changing Text

- - -
-
end-of-file (usually C-d) - -
-The character indicating end-of-file as set, for example, by -stty(1). - -If this character is read when there are no characters -on the line, and point is at the beginning of the line, readline -interprets it as the end of input and returns -EOF. - - -
delete-char (C-d) - -
-Delete the character at point. -If this function is bound to the -same character as the tty EOF character, as C-d -commonly is, see above for the effects. -This may also be bound to the Delete key on some keyboards. -
backward-delete-char (Rubout) - -
-Delete the character behind the cursor. -When given a numeric argument, -save the deleted text on the kill ring. -
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. -
quoted-insert (C-q, C-v) - -
-Add the next character typed to the line verbatim. -This is how to insert characters like C-q, for example. -
tab-insert (C-v TAB) - -
-Insert a tab character. -
self-insert (a, b, A, 1, !, ...) - -
-Insert the character typed. -
bracketed-paste-begin - -
-This function is intended to be bound to the - -escape -sequence sent by some terminals, and such a binding is assigned by default. -It allows readline to insert the pasted text as a single unit -without treating each character as if it had been read from the keyboard. -The pasted characters -are inserted as if each one was bound to self-insert instead of -executing any editing commands. -
-Bracketed paste sets the region to the inserted text and activates the region. -
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. -
transpose-words (M-t) - -
-Drag the word before point past the word after point, -moving point past that word as well. -If point is at the end of the line, this transposes -the last two words on the line. -
shell-transpose-words (M-C-t) - -
-Drag the word before point past the word after point, -moving point past that word as well. -If the insertion point is at the end of the line, this transposes -the last two words on the line. -Word boundaries are the same as shell-forward-word and -shell-backward-word. -
upcase-word (M-u) - -
-Uppercase the current (or following) word. -With a negative argument, -uppercase the previous word, but do not move point. -
downcase-word (M-l) - -
-Lowercase the current (or following) word. -With a negative argument, -lowercase the previous word, but do not move point. -
capitalize-word (M-c) - -
-Capitalize the current (or following) word. -With a negative argument, -capitalize the previous word, but do not move point. -
overwrite-mode - -
-Toggle overwrite mode. -With an explicit positive numeric argument, switches to overwrite mode. -With an explicit non-positive numeric argument, switches to insert mode. -This command affects only emacs mode; -vi mode does overwrite differently. -Each call to readline() starts in insert mode. -
-In overwrite mode, characters bound to self-insert replace -the text at point rather than pushing the text to the right. -Characters bound to backward-delete-char replace the character -before point with a space. -By default, this command is unbound, -but may be bound to the Insert key on some keyboards. - -
-  -

Killing and Yanking

- - -
-
kill-line (C-k) - -
-Kill the text from point to the end of the current line. -With a negative numeric argument, kill backward from the cursor to the -beginning of the line. -
backward-kill-line (C-x Rubout) - -
-Kill backward to the beginning of the current line. -With a negative numeric argument, kill forward from the cursor to the -end of the line. -
unix-line-discard (C-u) - -
-Kill backward from point to the beginning of the line, -saving the killed text on the kill-ring. - -
kill-whole-line - -
-Kill all characters on the current line, no matter where point is. -
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 forward-word. -
backward-kill-word (M-Rubout) - -
-Kill the word behind point. -Word boundaries are the same as those used by backward-word. -
shell-kill-word (M-C-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 shell-forward-word. -
shell-backward-kill-word - -
-Kill the word behind point. -Word boundaries are the same as those used by shell-backward-word. -
unix-word-rubout (C-w) - -
-Kill the word behind point, using white space as a word boundary, -saving the killed text on the kill-ring. -
unix-filename-rubout - -
-Kill the word behind point, using white space and the slash character -as the word boundaries, -saving the killed text on the kill-ring. -
delete-horizontal-space (M-\) - -
-Delete all spaces and tabs around point. -
kill-region - -
-Kill the text in the current region. -
copy-region-as-kill - -
-Copy the text in the region to the kill buffer, -so it can be yanked immediately. -
copy-backward-word - -
-Copy the word before point to the kill buffer. -The word boundaries are the same as backward-word. -
copy-forward-word - -
-Copy the word following point to the kill buffer. -The word boundaries are the same as forward-word. -
yank (C-y) - -
-Yank the top of the kill ring into the buffer at point. -
yank-pop (M-y) - -
-Rotate the kill ring, and yank the new top. -Only works following -yank - -or -yank-pop. - - -
-  -

Numeric Arguments

- - -
-
digit-argument (M-0, M-1, ..., M--) - -
-Add this digit to the argument already accumulating, or start a new -argument. -M-- starts a negative argument. -
universal-argument - -
-This is another way to specify an argument. -If this command is followed by one or more digits, optionally with a -leading minus sign, those digits define the argument. -If the command is followed by digits, executing -universal-argument - -again ends the numeric argument, but is otherwise ignored. -As a special case, if this command is immediately followed by a -character that is neither a digit nor 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. - -
-  -

Completing

- - -
-
complete (TAB) - -
-Attempt to perform completion on the text before point. -Bash - -attempts completion by first checking for any programmable -completions for the command word (see Programmable Completion below), -otherwise treating the text as a -variable (if the text begins with $), -username (if the text begins with ~), -hostname (if the text begins with @), or -command (including aliases, functions, and builtins) in turn. -If none of these produces a match, it falls back to filename completion. -
possible-completions (M-?) - -
-List the possible completions of the text before point. -When displaying completions, readline sets the number of columns used -for display to the value of completion-display-width, the value of -the shell variable -COLUMNS, +active−region−start−color variable. +The enable−active−region readline +variable turns this on and off. Several commands set the +region to active; those are noted below.

- -or the screen width, in that order. -
insert-completions (M-*) +

Commands for Moving + +

-
-Insert all completions of the text before point -that would have been generated by -possible-completions, -separated by a space. -
menu-complete - -
-Similar to complete, but replaces the word to be completed -with a single match from the list of possible completions. -Repeatedly executing menu-complete steps through the list -of possible completions, inserting each match in turn. -At the end of the list of completions, -menu-complete rings the bell -(subject to the setting of bell-style) -and restores the original text. -An argument of n moves n positions forward in the list -of matches; a negative argument moves backward through the list. -This command is intended to be bound to TAB, but is unbound -by default. -
menu-complete-backward - -
-Identical to menu-complete, but moves backward through the list -of possible completions, as if menu-complete had been given a -negative argument. -This command is unbound by default. -
export-completions - -
-Perform completion on the word before point as described above -and write the list of possible completions to readline's output -stream using the following format, writing information on separate lines: -
- -
-
*
- -the number of matches N; -
*
-the word being completed; -
*
-S:E, -where S and E are the start and end offsets of the word -in the readline line buffer; then -
*
-each match, one per line -
- - -
-If there are no matches, the first line will be - -and this command does not print any output after the S:E. -If there is only a single match, this prints a single line containing it. -If there is more than one match, this prints the common prefix of the -matches, which may be empty, on the first line after the S:E, -then the matches on subsequent lines. -In this case, N will include the first line with the common prefix. -
-The user or application -should be able to accommodate the possibility of a blank line. -The intent is that the user or application reads N lines after -the line containing S:E to obtain the match list. -This command is unbound by default. -
delete-char-or-list - -
-Deletes the character under the cursor if not at the beginning or -end of the line (like delete-char). -At the end of the line, it behaves identically to possible-completions. -This command is unbound by default. -
complete-filename (M-/) - -
-Attempt filename completion on the text before point. -
possible-filename-completions (C-x /) - -
-List the possible completions of the text before point, -treating it as a filename. -
complete-username (M-~) - -
-Attempt completion on the text before point, treating -it as a username. -
possible-username-completions (C-x ~) - -
-List the possible completions of the text before point, -treating it as a username. -
complete-variable (M-$) - -
-Attempt completion on the text before point, treating -it as a shell variable. -
possible-variable-completions (C-x $) - -
-List the possible completions of the text before point, -treating it as a shell variable. -
complete-hostname (M-@) - -
-Attempt completion on the text before point, treating -it as a hostname. -
possible-hostname-completions (C-x @) - -
-List the possible completions of the text before point, -treating it as a hostname. -
complete-command (M-!) - -
-Attempt completion on the text before point, treating -it as a command name. -Command completion attempts to -match the text against aliases, reserved words, shell -functions, shell builtins, and finally executable filenames, -in that order. -
possible-command-completions (C-x !) - -
-List the possible completions of the text before point, -treating it as a command name. -
dynamic-complete-history (M-TAB) - -
-Attempt completion on the text before point, comparing -the text against history list entries for possible -completion matches. -
dabbrev-expand - -
-Attempt menu completion on the text before point, comparing -the text against lines from the history list for possible -completion matches. -
complete-into-braces (M-{) - -
-Perform filename completion and insert the list of possible completions -enclosed within braces so the list is available to the shell (see -Brace Expansion - -above). - -
-  -

Keyboard Macros

- - -
-
start-kbd-macro (C-x () - -
-Begin saving the characters typed into the current keyboard macro. -
end-kbd-macro (C-x )) - -
-Stop saving the characters typed into the current keyboard macro -and store the definition. -
call-last-kbd-macro (C-x e) - -
-Re-execute the last keyboard macro defined, by making the characters -in the macro appear as if typed at the keyboard. -
print-last-kbd-macro () - -
-Print the last keyboard macro defined in a format suitable for the -inputrc file. - -
-  -

Miscellaneous

- - -
-
re-read-init-file (C-x C-r) - -
-Read in the contents of the inputrc file, and incorporate -any bindings or variable assignments found there. -
abort (C-g) - -
-Abort the current editing command and -ring the terminal's bell (subject to the setting of -bell-style). - -
do-lowercase-version (M-A, M-B, M-x, ...) - -
-If the metafied character x is uppercase, run the command -that is bound to the corresponding metafied lowercase character. -The behavior is undefined if x is already lowercase. -
prefix-meta (ESC) - -
-Metafy the next character typed. -ESC - - -f - -is equivalent to -Meta-f. - -
undo (C-_, C-x C-u) - -
-Incremental undo, separately remembered for each line. -
revert-line (M-r) - -
-Undo all changes made to this line. -This is like executing the -undo - -command enough times to return the line to its initial state. -
tilde-expand (M-&) - -
-Perform tilde expansion on the current word. -
set-mark (C-@, M-<space>) - -
-Set the mark to the point. -If a numeric argument is supplied, set the mark to that position. -
exchange-point-and-mark (C-x C-x) - -
-Swap the point with the mark. -Set the current cursor position to the saved position, -then set the mark to the old cursor position. -
character-search (C-]) - -
-Read a character and move point to the next occurrence of that character. -A negative argument searches for previous occurrences. -
character-search-backward (M-C-]) - -
-Read a character and move point to the previous occurrence of that character. -A negative argument searches for subsequent occurrences. -
skip-csi-sequence - -
-Read enough characters to consume a multi-key sequence such as those -defined for keys like Home and End. -CSI sequences begin with a Control Sequence Indicator (CSI), usually -ESC [. - -If this sequence is bound to - -keys producing CSI sequences 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 [. - -
insert-comment (M-#) - -
-Without a numeric argument, insert the value of the readline -comment-begin - -variable at the beginning of the current line. -If a numeric argument is supplied, this command acts as a toggle: if -the characters at the beginning of the line do not match the value -of comment-begin, insert the value; otherwise delete -the characters in comment-begin from the beginning of the line. -In either case, the line is accepted as if a newline had been typed. -The default value of -comment-begin causes this command to make the current line -a shell comment. -If a numeric argument causes the comment character to be removed, the line -will be executed by the shell. -
spell-correct-word (C-x s) - -
-Perform spelling correction on the current word, treating it as a directory -or filename, in the same way as the cdspell shell option. -Word boundaries are the same as those used by shell-forward-word. -
glob-complete-word (M-g) - -
-Treat the word before point as a pattern for pathname expansion, -with an asterisk implicitly appended, then use the pattern to -generate a list of matching file names for possible completions. -
glob-expand-word (C-x *) - -
-Treat the word before point as a pattern for pathname expansion, -and insert the list of matching file names, replacing the word. -If a numeric argument is supplied, append a * before -pathname expansion. -
glob-list-expansions (C-x g) - -
-Display the list of expansions that would have been generated by -glob-expand-word - -and redisplay the line. -If a numeric argument is supplied, append a * before -pathname expansion. -
dump-functions - -
-Print all of the functions and their key bindings -to the readline output stream. -If a numeric argument is supplied, -the output is formatted in such a way that it can be made part -of an inputrc file. -
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 inputrc file. -
dump-macros - -
-Print all of the readline key sequences bound to macros and the -strings they output -to the readline output stream. -If a numeric argument is supplied, -the output is formatted in such a way that it can be made part -of an inputrc file. -
execute-named-command (M-x) - -
-Read a bindable readline command name from the input and execute the -function to which it's bound, as if the key sequence to which it was -bound appeared in the input. -If this function is supplied with a numeric argument, it passes that -argument to the function it executes. -
display-shell-version (C-x C-v) - -
-Display version information about the current instance of -bash. - - -
-  -

Programmable Completion

- -When a user attempts word completion -for a command or an argument to a command for -which a completion specification (a compspec) has been defined -using the complete builtin -(see -SHELL BUILTIN COMMANDS - - -below), -readline invokes the programmable completion facilities. -

- -First, bash identifies the command name. -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 the empty string (completion attempted at the -beginning of an empty line), bash uses any compspec defined with -the -E option to complete. -The -I option to complete -indicates that the command word is the first non-assignment word -on the line, or after a command delimiter such as -; or |. -This usually indicates command name completion. -

- -If the command word is a full pathname, bash -searches for a compspec for the full pathname first. -If there is no compspec for the full pathname, bash attempts to -find a compspec for the portion following the final slash. -If those searches do not result in a compspec, -or if there is no compspec for the command word, -bash uses any compspec defined with -the -D option to complete as the default. -If there is no default compspec, bash performs alias expansion -on the command word as a final resort, -and attempts to find a compspec for the command word -resulting from any successful expansion. -

- -If a compspec is not found, bash performs its default completion as -described above under Completing. -Otherwise, once a compspec has been found, bash uses it to generate -the list of matching words. -

- -First, bash performs the actions specified by the compspec. -This only returns matches which are prefixes -of the word being completed. -When the --f - -or --d - -option is used for filename or directory name completion, -bash uses the shell variable -FIGNORE - - -to filter the matches. -

- -Next, programmable completion generates matches -specified by a pathname expansion pattern -supplied as an argument to the --G option. -The words generated by the pattern need not match the word -being completed. -Bash -uses the -FIGNORE - - -variable to filter the matches, but does not use the -GLOBIGNORE - - -shell variable. -

- -Next, completion considers -the string specified as the argument to the -W option. -The string is first split using the characters in the -IFS - - -special variable as delimiters. -This honors shell quoting within the string, in order to provide a -mechanism for the words to contain shell metacharacters or characters -in the value of -IFS. - - -Each word is then expanded using -brace expansion, tilde expansion, parameter and variable expansion, -command substitution, and arithmetic expansion, -as described above under -EXPANSION. - - -The results are split using the rules described above under -Word Splitting. -The results of the expansion are prefix-matched against the word being -completed, and the matching words become possible completions. -

- -After these matches have been generated, -bash executes any shell function or command -specified with the -F and -C options. -When the command or function is invoked, bash -assigns values to the -COMP_LINE, - - -COMP_POINT, - - -COMP_KEY, - - -and -COMP_TYPE - - -variables as described above -under Shell Variables. -If a shell function is being invoked, bash -also sets the -COMP_WORDS - - -and -COMP_CWORD - - -variables. -When the function or command is invoked, -the first argument ($1) is the name of the command whose arguments -are being completed, -the second argument ($2) is the word being completed, -and the third argument ($3) is the word preceding the word being -completed on the current command line. -There is no filtering of the generated completions against the -word being completed; -the function or command has complete freedom in generating the matches -and they do not need to match a prefix of the word. -

- -Any function specified with -F is invoked first. -The function may use any of the shell facilities, including the -compgen and compopt -builtins described below, to generate the matches. -It must put the possible completions in the -COMPREPLY - - -array variable, one per array element. -

- -Next, any command specified with the -C option is invoked -in an environment equivalent to command substitution. -It should print a list of completions, one per line, to the -standard output. -Backslash will escape a newline, if necessary. -These are added to the set of possible completions. -

- -External commands that are invoked to generate completions ( - -receive the word preceding the completion word as an argument, -as described above. -This provides context that is sometimes useful, but may include -information that is considered sensitive or part of a word expansion -that will not appear in the command line after expansion. -That word may be visible in process listings or in audit logs. -This may be a concern to users and completion specification authors -if there is sensitive information on the command line before -expansion, since completion takes place before words are expanded. -If this is an issue, completion authors should use functions as -wrappers around external commands and pass context information to the -external command in a different way. -External completers can infer context from the -COMP_LINE - - -and -COMP_POINT - - -environment variables, but they need to ensure -they break words in the same way readline does, using the -COMP_WORDBREAKS - - -variable. -

- -After generating all of the possible completions, -bash applies any filter -specified with the -X option to the completions in the list. -The filter is a pattern as used for pathname expansion; a & -in the pattern is replaced with the text of the word being completed. -A literal & may be escaped with a backslash; the backslash -is removed before attempting a match. -Any completion that matches the pattern is removed from the list. -A leading ! negates the pattern; -in this case bash removes -any completion that does not match the pattern. -If the -nocasematch - -shell option is enabled, -bash performs the match without regard to the case -of alphabetic characters. -

- -Finally, programmable completion adds -any prefix and suffix specified with the --P and -S -options, respectively, to each completion, -and returns the result -to readline as the list of possible completions. -

- -If the previously-applied actions do not generate any matches, and the --o dirnames option was supplied to complete when the -compspec was defined, bash attempts directory name completion. -

- -If the -o plusdirs option was supplied to complete when the -compspec was defined, bash attempts directory name completion and -adds any matches to the set of possible completions. -

- -By default, if a compspec is found, whatever it generates is returned -to the completion code as the full set of possible completions. -The default bash completions and the readline -default of filename completion are disabled. -If the -o bashdefault option was supplied to complete when -the compspec was defined, -and the compspec generates no matches, -bash attempts its default completions. -If the compspec and, if attempted, the default bash completions -generate no matches, -and the -o default option was supplied to -complete when the compspec was defined, -programmable completion performs readline's default completion. -

- -The options supplied to complete and compopt -can control how readline treats the completions. -For instance, the -o fullquote option tells readline -to quote the matches as if they were filenames. -See the description of complete below -for details. -

- -When a compspec indicates that it wants directory name completion, -the programmable completion functions force readline -to append a slash to completed names which are symbolic links -to directories, subject to the value of the -mark-directories readline variable, -regardless of the setting of the -mark-symlinked-directories readline variable. -

- -There is some support for dynamically modifying completions. -This is most useful when used in combination with a default completion -specified with complete -D. -It's possible for shell functions executed as completion functions -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 can be used to build a set of completions dynamically -as completion is attempted, rather than loading them all at once. -

- -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: -

- -
-_completion_loader()
-{
-  . "
-/etc/bash_completion.d/$1.sh"
- 
-\
-

-
-

-    
->/dev/null 2>&1 && return 124
-}
-complete -D -F _completion_loader 
-\
-

-
-

-    
--o bashdefault -o default
-
- - -
- -  -

HISTORY

- -When the --o history - -option to the -set - -builtin is enabled, the shell provides access to the -command history, -the list of commands previously typed. -The value of the -HISTSIZE - - -variable is used as the -number of commands to save in a history list: -the shell saves the text of the last -HISTSIZE - - -commands (default 500). -The shell stores each command in the history list prior to -parameter and variable expansion (see -EXPANSION - - -above) but after history expansion is performed, subject to the -values of the shell variables -HISTIGNORE - - -and -HISTCONTROL. - - -

- -On startup, bash initializes the history list -by reading history entries from the -file named by the -HISTFILE - - -variable (default - -~/.bash_history). - -That file is referred to as the history file. -The history file is truncated, if necessary, -to contain no more than the number of history entries -specified by the value of the -HISTFILESIZE - - -variable. -If -HISTFILESIZE - - -is unset, or set to null, a non-numeric value, -or a numeric value less than zero, the history file is not truncated. -

- -When the history file is read, -lines beginning with the history comment character followed immediately -by a digit are interpreted as timestamps for the following history line. -These timestamps are optionally displayed depending on the value of the -HISTTIMEFORMAT - - -variable. -When present, history timestamps delimit history entries, making -multi-line entries possible. -

- -When a shell with history enabled exits, bash copies the last -$HISTSIZE - - -entries from the history list to -$HISTFILE. - - -If the -histappend - -shell option is enabled -(see the description of -shopt - -under -SHELL BUILTIN COMMANDS - - -below), bash appends the entries to the history file, -otherwise it overwrites the history file. -If -HISTFILE - - -is unset or null, -or if the history file is unwritable, the history is not saved. -After saving the history, bash truncates the history file -to contain no more than -HISTFILESIZE - - -lines as described above. -

- -If the -HISTTIMEFORMAT - - -variable is set, the shell writes -the timestamp information -associated with each history entry to the history file, -marked with the history comment character, so -timestamps are preserved across shell sessions. -This uses the history comment character to distinguish timestamps from -other history lines. -As above, when using -HISTTIMEFORMAT, - - -the timestamps delimit multi-line history entries. -

- -The -fc - -builtin command (see -SHELL BUILTIN COMMANDS - - -below) will list or edit and re-execute a portion of the history list. -The -history - -builtin can 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. -

- -The shell allows control over which commands are saved on the history list. -The -HISTCONTROL - - -and -HISTIGNORE - - -variables are used to save only a subset of the commands entered. -If the -cmdhist -shell option is enabled, the shell attempts to save each -line of a multi-line command in the same history entry, adding -semicolons where necessary to preserve syntactic correctness. -The -lithist - -shell option modifies cmdhist by saving -the command with embedded newlines instead of semicolons. -See the description of the -shopt - -builtin below under -SHELL BUILTIN COMMANDS - - -for information on setting and unsetting shell options. -  -

HISTORY EXPANSION

- -The shell supports a history expansion feature that -is similar to the history expansion in -csh. - -This section describes what syntax features are available. -

- -History expansion is enabled by default for interactive shells, -and can be disabled using the -+H - -option to the -set - -builtin command (see -SHELL BUILTIN COMMANDS - - -below). -Non-interactive shells do not perform history expansion by default, -but it can be enabled with - -

- -History expansions introduce words from the history list into -the input stream, making it easy to repeat commands, insert the -arguments to a previous command into the current input line, or -fix errors in previous commands quickly. -

- -History expansion is performed immediately after a complete line -is read, before the shell breaks it into words, and is performed -on each line individually. -The shell attempts to inform the history -expansion functions about quoting still in effect from previous lines. -

- -It takes place in two parts. -The first is to determine which history list entry -to use during substitution. -The second is to select portions of that entry to include into -the current one. -

- -The entry selected from the history is the event, -and the portions of that entry that are acted upon are words. -Various modifiers are available to manipulate the selected words. -The entry is split into words in the same fashion as when reading input, -so that several metacharacter-separated words surrounded by -quotes are considered one word. -The event designator selects the event, the optional -word designator selects words from the event, and -various optional modifiers are available to manipulate the -selected words. -

- -History expansions are introduced by the appearance of the -history expansion character, which is ! by default. -History expansions may appear anywhere in the input, but do not nest. -

- -Only backslash (\) and single quotes can quote -the history expansion character, but the history expansion character is -also treated as quoted if it immediately precedes the closing double quote -in a double-quoted string. -

- -Several characters inhibit history expansion if found immediately -following the history expansion character, even if it is unquoted: -space, tab, newline, carriage return, =, -and the other shell metacharacters defined above. -

- -There is a special abbreviation for substitution, active when the -quick substitution character (described above under -histchars) - -is the first character on the line. -It selects the previous history list entry, using an event designator -equivalent to !!, -and substitutes one string for another in that entry. -It is described below under Event Designators. -This is the only history expansion that does not begin with the history -expansion character. -

- -Several shell options settable with the -shopt - -builtin will modify history expansion behavior -(see the description of the -shopt - -builtin below).and -If the -histverify - -shell option is enabled, and -readline - -is being used, history substitutions are not immediately passed to -the shell parser. -Instead, the expanded line is reloaded into the -readline - -editing buffer for further modification. -If -readline - -is being used, and the -histreedit - -shell option is enabled, a failed history substitution is reloaded -into the -readline - -editing buffer for correction. -

- -The --p - -option to the -history - -builtin command shows what a history expansion will -do before using it. -The --s - -option to the -history - -builtin will add commands to the end of the history list -without actually executing them, so that they are available for -subsequent recall. -

- -The shell allows control of the various characters used by the -history expansion mechanism (see the description of -histchars - -above under -Shell Variables). - -The shell uses -the history comment character to mark history timestamps when -writing the history file. -  -

Event Designators

- -An event designator is a reference to an entry in the history list. -The event designator -consists of the portion of the word beginning with the history -expansion character and ending with the word designator if present, -or the end of the word. -Unless the reference is absolute, events are relative to the current -position in the history list. -

+

beginning−of−line +(C−a)

-
-
! +

Move to the start of the +current line. This may also be bound to the Home key on some +keyboards.

-
-Start a history substitution, except when followed by a -blank, +

end−of−line +(C−e)

-newline, carriage return, =, -or, when the extglob shell option is enabled using -the shopt builtin, (. -
!n +

Move to the end of the line. +This may also be bound to the End key on some keyboards.

-
-Refer to history list entry -n. +

forward−char +(C−f)

-
!-n +

Move forward a character. This +may also be bound to the right arrow key on some +keyboards.

-
-Refer to the current entry minus -n. +

backward−char +(C−b)

-
!! +

Move back a character. This may +also be bound to the left arrow key on some keyboards.

-
-Refer to the previous entry. -This is a synonym for +

forward−word +(M−f)

-
!string +

Move forward to the end of the +next word. Words are composed of alphanumeric characters +(letters and digits).

-
-Refer to the most recent command preceding the current position in the -history list starting with -string. +

backward−word +(M−b)

-
!?string[?] +

Move back to the start of the +current or previous word. Words are composed of alphanumeric +characters (letters and digits).

-
-Refer to the most recent command preceding the current position in the -history list containing -string. -The trailing ? may be omitted if -string +

shell−forward−word +(M−C−f)

-is followed immediately by a newline. -If string is missing, this uses -the string from the most recent search; -it is an error if there is no previous search string. -
^string1^string2^ +

Move forward to the end of the +next word. Words are delimited by non-quoted shell +metacharacters.

-
-Quick substitution. -Repeat the previous command, replacing -string1 -with -string2. +

shell−backward−word +(M−C−b)

-Equivalent to +

Move back to the start of the +current or previous word. Words are delimited by non-quoted +shell metacharacters.

-(see Modifiers below). -
!# -
-The entire command line typed so far. +

previous−screen−line

-
-  -

Word Designators

+

Attempt to move point to the +same physical screen column on the previous physical screen +line. This will not have the desired effect if the current +readline line does not take up more than one physical +line or if point is not greater than the length of the +prompt plus the screen width.

-Word designators are used to select desired words from the event. -They are optional; if the word designator isn't supplied, the history -expansion uses the entire event. -A -: -separates the event specification from the word designator. -It may be omitted if the word designator begins with a -^, +

next−screen−line

-$, +

Attempt to move point to the +same physical screen column on the next physical screen +line. This will not have the desired effect if the current +readline line does not take up more than one physical +line or if the length of the current readline line is +not greater than the length of the prompt plus the screen +width.

-*, +

clear−display +(M−C−l)

--, +

Clear the screen and, if +possible, the terminal’s scrollback buffer, then +redraw the current line, leaving the current line at the top +of the screen.

-or -%. +

clear−screen +(C−l)

-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. -

+

Clear the screen, then redraw +the current line, leaving the current line at the top of the +screen. With a numeric argument, refresh the current line +without clearing the screen.

-
-
0 (zero) +

redraw−current−line

-
-The zeroth word. -For the shell, this is the command word. -
n +

Refresh the current line.

-
-The nth word. -
^ +

Commands for Manipulating the History + +

-
-The first argument: word 1. -
$ -
-The last word. -This is usually the last argument, but will expand to the -zeroth word if there is only one word in the line. -
% -
-The first word matched by the most recent +

accept−line +(Newline, Return)

-search, -if the search string begins with a character that is part of a word. -By default, searches begin at the end of each line and proceed to the -beginning, so the first word matched is the one closest to the end of -the line. -
x-y +

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 +HISTCONTROL and HISTIGNORE +variables. If the line is a modified history line, restore +the history line to its original state.

-
-A range of words; +

previous−history +(C−p)

-abbreviates +

Fetch the previous command from +the history list, moving back in the list. This may also be +bound to the up arrow key on some keyboards.

-
* +

next−history +(C−n)

-
-All of the words but the zeroth. -This is a synonym for +

Fetch the next command from the +history list, moving forward in the list. This may also be +bound to the down arrow key on some keyboards.

-It is not an error to use -* -if there is just one word in the event; -it expands to the empty string in that case. -
x* +

beginning−of−history +(M−<)

-
-Abbreviates x-$. -
x- +

Move to the first line in the +history.

-
-Abbreviates x-$ like x*, but omits the last word. -If x is missing, it defaults to 0. +

end−of−history +(M−>)

-
-

+

Move to the end of the input +history, i.e., the line currently being entered.

-If a word designator is supplied without an event specification, the -previous command is used as the event, equivalent to !!. -  -

Modifiers

-After the optional word designator, the expansion may include a -sequence of one or more of the following modifiers, each preceded by a +

operate−and−get−next +(C−o)

-These modify, or edit, the word or words selected from the history event. -

+

Accept the current line for +execution as if a newline had been entered, and fetch the +next line relative to the current line from the history for +editing. A numeric argument, if supplied, specifies the +history entry to use instead of the current line.

+

fetch−history

-
-
h +

With a numeric argument, fetch +that entry from the history list and make it the current +line. Without an argument, move back to the first entry in +the history list.

-
-Remove a trailing pathname component, leaving only the head. -
t -
-Remove all leading pathname components, leaving the tail. -
r +

reverse−search−history +(C−r)

-
-Remove a trailing suffix of the form .xxx, leaving the -basename. -
e +

Search backward starting at the +current line and moving “up” through the history +as necessary. This is an incremental search. This command +sets the region to the matched text and activates the +region.

-
-Remove all but the trailing suffix. -
p -
-Print the new command but do not execute it. -
q +

forward−search−history +(C−s)

-
-Quote the substituted words, escaping further substitutions. -
x +

Search forward starting at the +current line and moving “down” through the +history as necessary. This is an incremental search. This +command sets the region to the matched text and activates +the region.

-
-Quote the substituted words as with -q, -but break into words at -blanks +

non−incremental−reverse−search−history +(M−p)

-and newlines. -The q and x modifiers are mutually exclusive; -expansion uses the last one supplied. -
s/old/new/ +

Search backward through the +history starting at the current line using a non-incremental +search for a string supplied by the user. The search string +may match anywhere in a history line.

-
-Substitute -new -for the first occurrence of -old +

non−incremental−forward−search−history +(M−n)

-in the event line. -Any character may be used as the delimiter in place of /. -The final delimiter is optional if it is the last character of the -event line. -A single backslash quotes the delimiter in -old +

Search forward through the +history using a non-incremental search for a string supplied +by the user. The search string may match anywhere in a +history line.

-and -new. -If & appears in -new, +

history−search−backward

-it is replaced with -old. +

Search backward through the +history for the string of characters between the start of +the current line and the point. The search string must match +at the beginning of a history line. This is a +non-incremental search. This may be bound to the Page Up key +on some keyboards.

-A single backslash quotes the &. -If -old -is null, it is set to the last -old +

history−search−forward

-substituted, or, if no previous history substitutions took place, -the last -string +

Search forward through the +history for the string of characters between the start of +the current line and the point. The search string must match +at the beginning of a history line. This is a +non-incremental search. This may be bound to the Page Down +key on some keyboards.

-in a -!?string[?] -search. -If -new +

history−substring−search−backward

-is null, each matching -old +

Search backward through the +history for the string of characters between the start of +the current line and the point. The search string may match +anywhere in a history line. This is a non-incremental +search.

-is deleted. -
& -
-Repeat the previous substitution. -
g +

history−substring−search−forward

-
-Cause changes to be applied over the entire event line. -This is used in conjunction with +

Search forward through the +history for the string of characters between the start of +the current line and the point. The search string may match +anywhere in a history line. This is a non-incremental +search.

-(e.g., +

yank−nth−arg +(M−C−y)

-or +

Insert the first argument to +the previous command (usually the second word on the +previous line) at point. With an argument n, insert +the nth word from the previous command (the words in +the previous command begin with word 0). A negative argument +inserts the nth word from the end of the previous +command. Once the argument n is computed, this uses +the history expansion facilities to extract the nth +word, as if the “!n” history expansion +had been specified.

-If used with +

yank−last−arg +(M−., M−_)

-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 a may be used as a synonym for g. -
G +

Insert the last argument to the +previous command (the last word of the previous history +entry). With a numeric argument, behave exactly like +yank−nth−arg. Successive calls to +yank−last−arg 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). This uses the history expansion +facilities to extract the last word, as if the +“!$” history expansion had been specified.

-
-Apply the following -or +

shell−expand−line +(M−C−e)

-modifier once to each word in the event line. +

Expand the line by performing +shell word expansions. This performs alias and history +expansion, $'string' and +$"string" quoting, tilde expansion, +parameter and variable expansion, arithmetic expansion, +command and process substitution, word splitting, and quote +removal. An explicit argument suppresses command and process +substitution. See HISTORY EXPANSION +below for a description of history expansion.

-
-  -

SHELL BUILTIN COMMANDS

+

history−expand−line +(M−^)

+

Perform history expansion on +the current line. See HISTORY +EXPANSION below for a description of history +expansion.

-

+

magic−space

-Unless otherwise noted, each builtin command documented in this -section as accepting options preceded by -- +

Perform history expansion on +the current line and insert a space. See HISTORY +EXPANSION below for a description of history +expansion.

-accepts --- -to signify the end of the options. -The :, true, false, and test/[ builtins -do not accept options and do not treat -- specially. -The exit, logout, return, -break, continue, let, -and shift builtins accept and process arguments beginning with -- without requiring --. -Other builtins that accept arguments but are not specified as accepting -options interpret arguments beginning with - as invalid options and -require -- to prevent this interpretation. -

+

alias−expand−line

+

Perform alias expansion on the +current line. See ALIASES above for a +description of alias expansion.

-
-
: [arguments]
-No effect; the command does nothing beyond expanding -arguments +

history−and−alias−expand−line

-and performing any specified -redirections. -The return status is zero. -
. [-p path] filename [arguments]
+

Perform history and alias +expansion on the current line.

-
source [-p path] filename [arguments]
-The . command (source) reads and execute commands from -filename +

insert−last−argument +(M−., M−_)

-in the current shell environment and returns the exit status of the -last command executed from -filename. +

A synonym for +yank−last−arg.

-
-If filename does not contain a slash, . searches for it. -If the -p option is supplied, . treats path -as a colon-separated list of directories in which to find filename; -otherwise, . uses the entries in -PATH - -to find the directory containing -filename. +

edit−and−execute−command +(C−x C−e)

-filename does not need to be executable. -When bash is not in posix mode, it searches -the current directory if filename is not found in -PATH, +

Invoke an editor on the current +command line, and execute the result as shell commands. +Bash attempts to invoke +$VISUAL, +$EDITOR, and emacs as the editor, in +that order.

- -but does not search the current directory if -p is supplied. -If the -sourcepath +

Commands for Changing Text + +

-option to the -shopt -builtin command is turned off, . does not search -PATH. - -
-If any arguments are supplied, they become the positional -parameters when filename is executed. -Otherwise the positional parameters are unchanged. -
-If the -T option is enabled, . inherits any trap on -DEBUG; if it is not, any DEBUG trap string is saved and -restored around the call to ., and . unsets the -DEBUG trap while it executes. -If -T is not set, and the sourced file changes -the DEBUG trap, the new value persists after . completes. -The return status is the status of the last command executed from -filename (0 if no commands are executed), and non-zero if -filename - -is not found or cannot be read. -
alias [-p] [name[=value] ...]
-With no arguments or with the --p - -option, alias prints the list of aliases in the form -alias name=value on standard output. -When arguments are supplied, define an alias for -each name whose value is given. -A trailing space in value causes the next word to be -checked for alias substitution when the alias is expanded -during command parsing. -For each name in the argument list for which no value -is supplied, print the name and value of the alias name. -alias returns true unless a name is given -(without a corresponding =value) -for which no alias has been defined. -
bg [jobspec ...]
-Resume each suspended job jobspec in the background, as if it -had been started with -&. - -If -jobspec - -is not present, the shell uses its notion of the current job. -bg - -jobspec - -returns 0 unless run when job control is disabled or, when run with -job control enabled, any specified jobspec was not found -or was started without job control. -
bind [-m keymap] [-lsvSVX]
- -
bind [-m keymap] [-q function] [-u function] [-r keyseq]
-
bind [-m keymap] -f filename
-
bind [-m keymap] -x keyseq[:] shell-command
-
bind [-m keymap] keyseq:function-name
-
bind [-m keymap] -p|-P [readline-command]
-
bind [-m keymap] keyseq:readline-command
-
bind readline-command-line
- -Display current -readline +

end−of−file +(usually C−d)

-key and function bindings, bind a key sequence to a -readline - -function or macro -or to a shell command, or set a -readline - -variable. -Each non-option argument is a key binding or command as it would appear in a -readline - -initialization file such as -.inputrc, - -but each binding or command must be passed as a separate argument; -e.g., '" -\C-x\C-r" -: re-read-init-file'. -In the following descriptions, output available to be re-read is formatted -as commands that would appear in a -readline - -initialization file or that would be supplied as individual arguments to a -bind - -command. -Options, if supplied, have the following meanings: -
- -
-
-m keymap - -
-Use -keymap - -as the keymap to be affected by the subsequent bindings. -Acceptable -keymap - -names are -emacs, emacs-standard, emacs-meta, emacs-ctlx, vi, -vi-move, vi-command, and -vi-insert. - -vi is equivalent to vi-command -(vi-move is also a synonym); -emacs is equivalent to emacs-standard. -
-l - -
-List the names of all readline functions. -
-p - -
-Display readline function names and bindings in such a way -that they can be -used as an argument to a subsequent -bind command or in a readline initialization file. -If arguments remain after option processing, bind treats -them as readline command names and restricts output to those names. -
-P - -
-List current readline function names and bindings. -If arguments remain after option processing, bind treats -them as readline command names and restricts output to those names. -
-s - -
-Display readline key sequences bound to macros and the strings -they output in such a way that they can be used -as an argument to a subsequent bind command -or in a readline initialization file. -
-S - -
-Display readline key sequences bound to macros and the strings -they output. -
-v - -
-Display readline variable names and values in such a way that they -can be -used as an argument to a subsequent -bind command or in a readline initialization file. -
-V - -
-List current readline variable names and values. -
-f filename - -
-Read key bindings from filename. -
-q function - -
-Display key sequences that invoke the named readline function. -
-u function - -
-Unbind all key sequences bound to the named readline function. -
-r keyseq - -
-Remove any current binding for keyseq. -
-x keyseq[: ]shell-command - -
-Cause shell-command to be executed whenever keyseq is -entered. -The separator between keyseq and shell-command is either -whitespace or a colon optionally followed by whitespace. -If the separator is whitespace, shell-command -must be enclosed in double quotes and readline expands any of its -special backslash-escapes in shell-command before saving it. -If the separator is a colon, any enclosing double quotes are optional, and -readline does not expand the command string before saving it. -Since the entire key binding expression must be a single argument, it -should be enclosed in single quotes. -When shell-command is executed, the shell sets the -READLINE_LINE - - -variable to the contents of the readline line buffer and the -READLINE_POINT - - -and -READLINE_MARK - - -variables to the current location of the insertion point and the saved -insertion point (the mark), respectively. -The shell assigns any numeric argument the user supplied to the -READLINE_ARGUMENT - - -variable. -If there was no argument, that variable is not set. -If the executed command changes the value of any of -READLINE_LINE, - - -READLINE_POINT, - - -or -READLINE_MARK, - - -those new values will be reflected in the editing state. -
-X - -
-List all key sequences bound to shell commands and the associated commands -in a format that can be reused as -an argument to a subsequent bind command. - -
-

- -The return value is 0 unless an unrecognized option is supplied or an -error occurred. -

- -
break [n]
-Exit from within a -for, - -while, - -until, - -or -select - -loop. -If n is specified, break exits n enclosing loops. -n - -must be >= 1. If -n - -is greater than the number of enclosing loops, all enclosing loops -are exited. -The return value is 0 unless n is not greater than or equal to 1. -
builtin shell-builtin [arguments]
-Execute the specified shell builtin shell-builtin, passing it -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 cd builtin is commonly redefined this way. -The return status is false if -shell-builtin - -is not a shell builtin command. -
caller [expr]
-Returns the context of any active subroutine call (a shell function or -a script executed with the . or source builtins). -
-Without expr, caller displays the line number and source -filename of the current subroutine call. -If a non-negative integer is supplied as expr, caller -displays the line number, subroutine name, and source file corresponding -to that position in the current execution call stack. -This extra information may be used, for example, to print a stack trace. -The current frame is frame 0. -
-The return value is 0 unless the shell is not executing a subroutine -call or expr does not correspond to a valid position in the -call stack. -
-
-cd [-L] [-@] [dir] -
cd -P [-e] [-@] [dir]
- -Change the current directory to dir. -if dir is not supplied, the value of the -HOME - - -shell variable is used as dir. -If dir is the empty string, cd treats it as an error. -The variable -CDPATH - - -exists, -and dir does not begin with a slash (/), -cd uses it as a search path: -the shell searches each directory name in -CDPATH - - -for dir. -Alternative directory names in -CDPATH - - -are separated by a colon (:). -A null directory name in -CDPATH - - -is the same as the current directory, i.e., - -
-The --P - -option causes cd to use the physical directory structure -by resolving symbolic links while traversing dir and -before processing instances of - -.. - -in dir (see also the --P - -option to the -set - -builtin command). -
-The --L - -option forces cd to follow symbolic links by resolving the link -after processing instances of - -.. - -in dir. -If - -.. - -appears in dir, cd processes it by removing the -immediately previous pathname component from dir, back to a slash -or the beginning of dir, -and verifying that the portion of dir it has processed to -that point is still a valid directory name after removing the pathname -component. -If it is not a valid directory name, cd returns a non-zero status. -If neither --L - -nor --P - -is supplied, -cd - -behaves as if --L - -had been supplied. -
-If the --e - -option is supplied with --P, - -and cd cannot successfully determine the current working directory -after a successful directory change, it returns a non-zero status. -
-On systems that support it, the -@ option presents the extended -attributes associated with a file as a directory. -
-An argument of -- +

The character indicating +end-of-file as set, for example, by stty(1). If this +character is read when there are no characters on the line, +and point is at the beginning of the line, readline +interprets it as the end of input and returns +EOF.

-is converted to -$OLDPWD +

delete−char +(C−d)

- -before attempting the directory change. -
-If cd uses a non-empty directory name from -CDPATH, +

Delete the character at point. +If this function is bound to the same character as the tty +EOF character, as C−d commonly is, see +above for the effects. This may also be bound to the Delete +key on some keyboards.

- -or if - is the first argument, and the directory change is -successful, cd writes the absolute pathname of the new -working directory to the standard output. -
-If the directory change is successful, cd sets the value of the -PWD environment variable to the new directory name, and sets the -OLDPWD environment variable to the value of the current working -directory before the change. -
-The return value is true if the directory was successfully changed; -false otherwise. -
command [-pVv] command [arg ...]
-The command builtin runs -command - -with -args - -suppressing the normal shell function lookup for command. -Only builtin commands or commands found in the -PATH - - -named command are executed. -If the --p - -option is supplied, the search for -command - -is performed using a default value for -PATH - - -that is guaranteed to find all of the standard utilities. -
-If either the --V - -or --v - -option is supplied, command prints a description of -command. - -The --v - -option displays a single word indicating the command or filename -used to invoke -command; - -the --V - -option produces a more verbose description. -
-If the --V - -or --v - -option is supplied, the exit status is zero if -command - -was found, and non-zero if not. -If neither option is supplied and an error occurred or -command - -cannot be found, the exit status is 127. -Otherwise, the exit status of the -command - -builtin is the exit status of -command. - -
compgen [-V varname] [option] [word]
-Generate possible completion matches for word according to -the options, which may be any option accepted by the -complete - -builtin with the exceptions of --p, - --r, - --D, - --E, - -and --I, - -and write the matches to the standard output. -
-If the -V option is supplied, compgen stores the generated -completions into the indexed array variable varname instead of writing -them to the standard output. -
-When using the -F or -C options, the various shell variables -set by the programmable completion facilities, while available, will not -have useful values. -
-The matches will be generated in the same way as if the programmable -completion code had generated them directly from a completion specification -with the same flags. -If word is specified, only those completions matching word -will be displayed or stored. -
-The return value is true unless an invalid option is supplied, or no -matches were generated. -
complete [-abcdefgjksuv] [-o comp-option] [-DEI] [-A action]
-
- -[-G globpat] [-W wordlist] [-F function] [-C command] -
- -[-X filterpat] [-P prefix] [-S suffix] name [name ...] - -
complete -pr [-DEI] [name ...]
- -Specify how arguments to each name should be completed. -
-If the -p option is supplied, or if no options or names -are supplied, print existing completion specifications -in a way that allows them to be reused as input. -The -r option removes a completion specification for -each name, or, if no names are supplied, all -completion specifications. -
-The -D option indicates that other supplied options and actions should -apply to the - -command completion; that is, completion attempted -on a command for which no completion has previously been defined. -The -E option indicates that other supplied options and actions should -apply to -command completion; that is, completion attempted on a -blank line. -The -I option indicates that other supplied options and actions should -apply to completion on the initial non-assignment word on the line, or after -a command delimiter such as ; or |, which is usually command -name completion. -If multiple options are supplied, the -D option takes precedence -over -E, and both take precedence over -I. -If any of -D, -E, or -I are supplied, any other -name arguments are ignored; these completions only apply to the case -specified by the option. -
-The process of applying these completion specifications when -attempting word completion is described - -above under Programmable Completion. -
-Other options, if specified, have the following meanings. -The arguments to the -G, -W, and -X options -(and, if necessary, the -P and -S options) -should be quoted to protect them from expansion before the -complete - -builtin is invoked. -
-
- -
-
-o comp-option
-The comp-option controls several aspects of the compspec's behavior -beyond the simple generation of completions. -comp-option may be one of: -
-
-
bashdefault - -
-Perform the rest of the default bash completions if the compspec -generates no matches. -
default - -
-Use readline's default filename completion if the compspec generates -no matches. -
dirnames - -
-Perform directory name completion if the compspec generates no matches. -
filenames - -
-Tell readline that the compspec generates filenames, so it can perform -any filename-specific processing (such as adding a slash to directory names, -quoting special characters, or suppressing trailing spaces). -This is intended to be used with shell functions. -
fullquote - -
-Tell readline to quote all the completed words even if they are not -filenames. -
noquote - -
-Tell readline not to quote the completed words if they are filenames -(quoting filenames is the default). -
nosort - -
-Tell readline not to sort the list of possible completions -alphabetically. -
nospace - -
-Tell readline not to append a space (the default) to words completed -at the end of the line. -
plusdirs - -
-After generating any matches defined by the compspec, -attempt directory name completion and add any -matches to the results of the other actions. -
- -
-A action
-The action may be one of the following to generate a list of possible -completions: -
-
-
alias - -
-Alias names. -May also be specified as -a. -
arrayvar - -
-Array variable names. -
binding - -
-Readline key binding names. -
builtin - -
-Names of shell builtin commands. -May also be specified as -b. -
command - -
-Command names. -May also be specified as -c. -
directory - -
-Directory names. -May also be specified as -d. -
disabled - -
-Names of disabled shell builtins. -
enabled - -
-Names of enabled shell builtins. -
export - -
-Names of exported shell variables. -May also be specified as -e. -
file - -
-File and directory names, similar to readline's filename completion. -May also be specified as -f. -
function - -
-Names of shell functions. -
group - -
-Group names. -May also be specified as -g. -
helptopic - -
-Help topics as accepted by the help builtin. -
hostname - -
-Hostnames, as taken from the file specified by the -HOSTFILE - - -shell variable. -
job - -
-Job names, if job control is active. -May also be specified as -j. -
keyword - -
-Shell reserved words. -May also be specified as -k. -
running - -
-Names of running jobs, if job control is active. -
service - -
-Service names. -May also be specified as -s. -
setopt - -
-Valid arguments for the -o option to the set builtin. -
shopt - -
-Shell option names as accepted by the shopt builtin. -
signal - -
-Signal names. -
stopped - -
-Names of stopped jobs, if job control is active. -
user - -
-User names. -May also be specified as -u. -
variable - -
-Names of all shell variables. -May also be specified as -v. -
- -
-C command
-command is executed in a subshell environment, and its output is -used as the possible completions. -Arguments are passed as with the -F option. -
-F function
-The shell function function is executed in the current shell -environment. -When the function is executed, -the first argument ($1) is the name of the command whose arguments are -being completed, -the second argument ($2) is the word being completed, and -the third argument ($3) is the word preceding the word being -completed on the current command line. -When function finishes, -programmable completion retrieves -the possible completions from the value of the -COMPREPLY - - -array variable. -
-G globpat
-Expand the pathname expansion pattern globpat to generate -the possible completions. -
-P prefix
-Add prefix to the beginning of each possible completion -after all other options have been applied. -
-S suffix
-Append suffix to each possible completion -after all other options have been applied. -
-W wordlist
-Split the wordlist using the characters in the -IFS - - -special variable as delimiters, and expand each resulting word. -Shell quoting is honored within wordlist, -in order to provide a -mechanism for the words to contain shell metacharacters or characters -in the value of -IFS. - - -The possible completions are the members of the resultant list which -match a prefix of the word being completed. -
-X filterpat
-filterpat 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 -filterpat is removed from the list. -A leading ! in filterpat negates the pattern; in this -case, any completion not matching filterpat is removed. - -
-

- -The return value is true unless an invalid option is supplied, an option -other than --p, - --r, - --D, - --E, - -or --I - -is supplied without a name -argument, an attempt is made to remove a completion specification for -a name for which no specification exists, or -an error occurs adding a completion specification. -

- -
compopt [-o option] [-DEI] [+o option] [name]
-Modify completion options for each name according to the -options, or for the -currently-executing completion if no names are supplied. -If no options are supplied, display the completion options for each -name or the current completion. -The possible values of option are those valid for the complete -builtin described above. -
-The -D option indicates that other supplied options should -apply to the - -command completion; -the -E option indicates that other supplied options should -apply to - -command completion; and -the -I option indicates that other supplied options should -apply to completion on the initial word on the line. -These are determined in the same way as the complete builtin. -
-If multiple options are supplied, the -D option takes precedence -over -E, and both take precedence over -I. -
-The return value is true unless an invalid option is supplied, an attempt -is made to modify the options for a name for which no completion -specification exists, or an output error occurs. -
continue [n]
-continue resumes the next iteration of the enclosing -for, - -while, - -until, - -or -select - -loop. -If -n - -is specified, bash resumes the nth enclosing loop. -n - -must be >= 1. -If -n - -is greater than the number of enclosing loops, the shell resumes -the last enclosing loop -(the - -loop). -The return value is 0 unless n is not greater than or equal to 1. -
declare [-aAfFgiIlnrtux] [-p] [name[=value] ...]
- -
typeset [-aAfFgiIlnrtux] [-p] [name[=value] ...]
- -Declare variables and/or give them attributes. -If no names are given then display the values of variables -or functions. -The --p +

backward−delete−char +(Rubout)

-option will display the attributes and values of each -name. - -When --p - -is used with name arguments, additional options, -other than -f and -F, are ignored. -
-When --p - -is supplied without name arguments, -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 -p, declare will -display the attributes and values of all shell variables. -The -f option restricts the display to shell functions. -
-The --F - -option inhibits the display of function definitions; only the -function name and attributes are printed. -If the extdebug shell option is enabled using shopt, -the source file name and line number where each name -is defined are displayed as well. -The --F - -option implies --f. - -
-The --g - -option forces variables to be created or modified at the global scope, -even when declare is executed in a shell function. -It is ignored when declare is not executed in a shell function. -
-The --I - -option causes local variables to inherit the attributes -(except the nameref attribute) -and value of any existing variable with the same -name at a surrounding scope. -If there is no existing variable, the local variable is initially unset. -
-The following options can -be used to restrict output to variables with the specified attribute or -to give variables attributes: -
- -
-
-a - -
-Each name is an indexed array variable (see -Arrays - - -above). -
-A - -
-Each name is an associative array variable (see -Arrays - - -above). -
-f - -
-Each name refers to a shell function. -
-i - -
-The variable is treated as an integer; -arithmetic evaluation (see -ARITHMETIC EVALUATION - - - -above) -is performed when the variable is assigned a value. -
-l - -
-When the variable is assigned a value, all upper-case characters are -converted to lower-case. -The upper-case attribute is disabled. -
-n - -
-Give each name the nameref attribute, making -it a name reference to another variable. -That other variable is defined by the value of name. -All references, assignments, and attribute modifications -to name, except those using or changing the --n attribute itself, are performed on the variable referenced by -name's value. -The nameref attribute cannot be applied to array variables. -
-r - -
-Make names readonly. -These names cannot then be assigned values -by subsequent assignment statements or unset. -
-t - -
-Give each name the trace attribute. -Traced functions inherit the DEBUG and RETURN traps from -the calling shell. -The trace attribute has no special meaning for variables. -
-u - -
-When the variable is assigned a value, all lower-case characters are -converted to upper-case. -The lower-case attribute is disabled. -
-x - -
-Mark each name for export to subsequent commands via the environment. - -
-

- -Using - -instead of - -turns off the specified -attribute instead, with the exceptions that +a and +A -may not be used to destroy array variables and +r will not -remove the readonly attribute. -

- -When used in a function, -declare - -and -typeset - -make each -name local, as with the -local - -command, -unless the -g option is supplied. -If a variable name is followed by =value, the value of -the variable is set to value. -When using -a or -A and the compound assignment syntax to -create array variables, additional attributes do not take effect until -subsequent assignments. -

- -The return value is 0 unless an invalid option is encountered, -an attempt is made to define a function using - -an attempt is made to assign a value to a readonly variable, -an attempt is made to assign a value to an array variable without -using the compound assignment syntax (see -Arrays - - -above), -one of the names is not a valid shell variable name, -an attempt is made to turn off readonly status for a readonly variable, -an attempt is made to turn off array status for an array variable, -or an attempt is made to display a non-existent function with -f. -

- -
dirs [-clpv] [+n] [-n] - -
-Without options, display 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 -pushd - -command; the -popd - -command removes entries from the list. -The current directory is always the first directory in the stack. -
-Options, if supplied, have the following meanings: -
- -
-
-c - -
-Clears the directory stack by deleting all of the entries. -
-l - -
-Produces a listing using full pathnames; -the default listing format uses a tilde to denote the home directory. -
-p - -
-Print the directory stack with one entry per line. -
-v - -
-Print the directory stack with one entry per line, -prefixing each entry with its index in the stack. -
+n
-Displays the nth entry counting from the left of the list -shown by -dirs - -when invoked without options, starting with zero. -
-n
-Displays the nth entry counting from the right of the list -shown by -dirs - -when invoked without options, starting with zero. - -
-

- -The return value is 0 unless an -invalid option is supplied or n indexes beyond the end -of the directory stack. -

- -
disown [-ar] [-h] [id ...]
-Without options, remove each -id - -from the table of active jobs. -Each id may be a job specification jobspec -or a process ID pid; -if id is a pid, -disown uses the job containing pid as jobspec. -
-If the -h option is supplied, -disown does not remove the jobs corresponding to each -id - -from the jobs table, -but rather marks them so the shell does not send -SIGHUP - - -to the job if the shell receives a -SIGHUP. - - -
-If no -id - -is supplied, the --a - -option means to remove or mark all jobs; the --r - -option without an -id - -argument removes or marks running jobs. -If no -id - -is supplied, and neither the -a nor the -r option -is supplied, disown removes or marks the current job. -
-The return value is 0 unless an -id - -does not specify a valid job. -
echo [-neE] [arg ...]
-Output the args, separated by spaces, followed by a newline. -The return status is 0 unless a write error occurs. -If -n is specified, the trailing newline is not printed. -
-If the -e option is given, echo interprets -the following backslash-escaped characters. -The --E +

Delete the character behind the +cursor. When given a numeric argument, save the deleted text +on the kill ring.

-option disables interpretation of these escape characters, -even on systems where they are interpreted by default. -The xpg_echo shell option determines -whether or not echo interprets any options -and expands these escape characters. -echo -does not interpret -- to mean the end of options. -
-echo +

forward−backward−delete−char

-interprets the following escape sequences: -
+

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.

-
-
\a +

quoted−insert +(C−q, C−v)

-
-alert (bell) -
\b +

Add the next character typed to +the line verbatim. This is how to insert characters like +C−q, for example.

-
-backspace -
\c +

tab−insert (C−v +TAB)

-
-suppress further output -
\e +

Insert a tab character.

-
-
\E +

self−insert (a, b, A, +1, !, ...)

-
-an escape character -
\f +

Insert the character typed.

-
-form feed -
\n -
-new line -
\r +

bracketed−paste−begin

-
-carriage return -
\t +

This function is intended to be +bound to the “bracketed paste” escape sequence +sent by some terminals, and such a binding is assigned by +default. It allows readline to insert the pasted text +as a single unit without treating each character as if it +had been read from the keyboard. The pasted characters are +inserted as if each one was bound to +self−insert instead of executing any editing +commands.
+Bracketed paste sets the region to the inserted text and +activates the region.

-
-horizontal tab -
\v +

transpose−chars +(C−t)

-
-vertical tab -
\\ +

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.

-
-backslash -
\0nnn +

transpose−words +(M−t)

-
-The eight-bit character whose value is the octal value nnn -(zero to three octal digits). -
\xHH +

Drag the word before point past +the word after point, moving point past that word as well. +If point is at the end of the line, this transposes the last +two words on the line.

-
-The eight-bit character whose value is the hexadecimal value HH -(one or two hex digits). -
\uHHHH -
-The Unicode (ISO/IEC 10646) character whose value is the hexadecimal value -HHHH (one to four hex digits). -
\UHHHHHHHH +

shell−transpose−words +(M-C-t)

-
-The Unicode (ISO/IEC 10646) character whose value is the hexadecimal value -HHHHHHHH (one to eight hex digits). +

Drag the word before point past +the word after point, moving point past that word as well. +If the insertion point is at the end of the line, this +transposes the last two words on the line. Word boundaries +are the same as shell−forward−word and +shell−backward−word.

-
-

+

upcase−word +(M−u)

-echo writes any unrecognized backslash-escaped characters unchanged. -
+

Uppercase the current (or +following) word. With a negative argument, uppercase the +previous word, but do not move point.

-
enable [-a] [-dnps] [-f filename] [name ...]
-Enable and disable builtin shell commands. -Disabling a builtin allows an executable file 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 files. -
-If -n is supplied, each name is disabled; otherwise, -names are enabled. -For example, to use the -test +

downcase−word +(M−l)

-binary found using -PATH +

Lowercase the current (or +following) word. With a negative argument, lowercase the +previous word, but do not move point.

- -instead of the shell builtin version, run +

capitalize−word +(M−c)

+

Capitalize the current (or +following) word. With a negative argument, capitalize the +previous word, but do not move point.

-``enable -n test''. +

overwrite−mode

+

Toggle overwrite mode. With an +explicit positive numeric argument, switches to overwrite +mode. With an explicit non-positive numeric argument, +switches to insert mode. This command affects only +emacs mode; vi mode does overwrite +differently. Each call to readline() starts in insert +mode.
+In overwrite mode, characters bound to +self−insert replace the text at point rather +than pushing the text to the right. Characters bound to +backward−delete−char replace the +character before point with a space. By default, this +command is unbound, but may be bound to the Insert key on +some keyboards.

+

Killing and Yanking + +

+

kill−line +(C−k)

-
-If no name arguments are supplied, or if the --p +

Kill the text from point to the +end of the current line. With a negative numeric argument, +kill backward from the cursor to the beginning of the +line.

-option is supplied, print a list of shell builtins. -With no other option arguments, the list consists of all enabled -shell builtins. -If -n is supplied, print only disabled builtins. -If -a is supplied, the list printed includes all builtins, with an -indication of whether or not each is enabled. -The -s option means to restrict the output to the -POSIX -special builtins. -
-The --f -option means to load the new builtin command -name +

backward−kill−line +(C−x Rubout)

-from shared object -filename, +

Kill backward to the beginning +of the current line. With a negative numeric argument, kill +forward from the cursor to the end of the line.

-on systems that support dynamic loading. -If filename does not contain a slash, -Bash will use the value of the BASH_LOADABLES_PATH variable as a -colon-separated list of directories in which to search for filename. -The default for BASH_LOADABLES_PATH is system-dependent, -and may include -to force a search of the current directory. -The --d +

unix−line−discard +(C−u)

-option will delete a builtin previously loaded with -f. -If -s is used with -f, the new builtin becomes a -POSIX -special builtin. -
-If no options are supplied and a name is not a shell builtin, -enable will attempt to load name from a shared -object named name, as if the command were +

Kill backward from point to the +beginning of the line, saving the killed text on the +kill-ring.

-``enable -f name name''. +

kill−whole−line

+

Kill all characters on the +current line, no matter where point is.

+

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 +forward−word.

+

backward−kill−word +(M−Rubout)

-
-The return value is 0 unless a -name +

Kill the word behind point. +Word boundaries are the same as those used by +backward−word.

-is not a shell builtin or there is an error loading a new builtin -from a shared object. -
eval [arg ...]
-Concatenate the args together into a single command, separating -them with spaces. -Bash then reads and execute this command, and returns its exit status -as the return status of eval. -If there are no -args, +

shell−kill−word +(M−C−d)

-or only null arguments, -eval +

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 +shell−forward−word.

-returns 0. -
exec [-cl] [-a name] [command [arguments]]
-If -command -is specified, it replaces the shell without creating a new process. -command cannot be a shell builtin or function. -The -arguments +

shell−backward−kill−word

-become the arguments to command. -If the --l +

Kill the word behind point. +Word boundaries are the same as those used by +shell−backward−word.

-option is supplied, -the shell places a dash at the beginning of the zeroth argument passed to -command. +

unix−word−rubout +(C−w)

-This is what -login(1) +

Kill the word behind point, +using white space as a word boundary, saving the killed text +on the kill-ring.

-does. The --c -option causes -command +

unix−filename−rubout

-to be executed with an empty environment. -If --a +

Kill the word behind point, +using white space and the slash character as the word +boundaries, saving the killed text on the kill-ring.

-is supplied, the shell passes -name - -as the zeroth argument to the executed command. -
-If -command - -cannot be executed for some reason, a non-interactive shell exits, -unless the -execfail - -shell option is enabled. -In that case, it returns a non-zero status. -An interactive shell returns a non-zero status if the file cannot be executed. -A subshell exits unconditionally if exec fails. -
-If -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. -
exit [n]
-Cause the shell to exit with a status of n. -If -n +

delete−horizontal−space +(M−\)

-is omitted, the exit status is that of the last command executed. -Any trap on -EXIT +

Delete all spaces and tabs +around point.

- -is executed before the shell terminates. -
export [-fn] [name[=value]] ...
+

kill−region

-
export -p [-f] +

Kill the text in the current +region.

-
-The supplied -names +

copy−region−as−kill

-are marked for automatic export to the environment of -subsequently executed commands. -If the --f +

Copy the text in the region to +the kill buffer, so it can be yanked immediately.

-option is given, the -names -refer to functions. -
-The --n +

copy−backward−word

-option unexports, or removes the export attribute, from each name. -If no -names +

Copy the word before point to +the kill buffer. The word boundaries are the same as +backward−word.

-are given, or if only the --p -option is supplied, -export displays a list of names of all exported -variables on the standard output. -Using -p and -f together displays exported functions. -The -p option displays output in a form that may be reused as input. -
-export allows the value of a variable to be set when it is exported -or unexported by following the variable name with =value. -This sets the value of the variable to value while modifying the -export attribute. -export +

copy−forward−word

-returns an exit status of 0 unless an invalid option is -encountered, -one of the names is not a valid shell variable name, or --f +

Copy the word following point +to the kill buffer. The word boundaries are the same as +forward−word.

-is supplied with a -name +

yank (C−y)

-that is not a function. -
false
-Does nothing; returns a non-zero status. -
fc [-e ename] [-lnr] [first] [last]
+

Yank the top of the kill ring +into the buffer at point.

-
fc -s [pat=rep] [cmd]
+

yank−pop +(M−y)

-The first form selects a range of commands from -first +

Rotate the kill ring, and yank +the new top. Only works following yank or +yank−pop.

-to -last +

Numeric Arguments + +

-from the history list and displays or edits and re-executes them. -First -and -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). -
-When listing, a first or last of 0 is equivalent to -1 -and -0 is equivalent to the current command -(usually the fc command); -otherwise 0 is equivalent to -1 and -0 is invalid. -If -last +

digit−argument +(M−0, M−1, ..., M−−)

-is not specified, it is set to -the current command for listing (so that +

Add this digit to the argument +already accumulating, or start a new argument. +M−− starts a negative argument.

-``fc -l -10'' +

universal−argument

+

This is another way to specify +an argument. If this command is followed by one or more +digits, optionally with a leading minus sign, those digits +define the argument. If the command is followed by digits, +executing universal−argument again ends the +numeric argument, but is otherwise ignored. As a special +case, if this command is immediately followed by a character +that is neither a digit nor 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.

+

Completing + +

+

complete +(TAB)

+

Attempt to perform completion +on the text before point. Bash attempts completion by +first checking for any programmable completions for the +command word (see Programmable Completion below), +otherwise treating the text as a variable (if the text +begins with $), username (if the text begins with +~), hostname (if the text begins with @), or +command (including aliases, functions, and builtins) in +turn. If none of these produces a match, it falls back to +filename completion.

-prints the last 10 commands) and to -first +

possible−completions +(M−?)

-otherwise. -If -first +

List the possible completions +of the text before point. When displaying completions, +readline sets the number of columns used for display +to the value of completion-display-width, the value +of the shell variable +COLUMNS, or the screen +width, in that order.

-is not specified, it is set to the previous -command for editing and -16 for listing. -
-If the --l +

insert−completions +(M−*)

-option is supplied, the commands are listed on the standard output. -The --n +

Insert all completions of the +text before point that would have been generated by +possible−completions, separated by a space.

-option suppresses -the command numbers when listing. -The --r +

menu−complete

-option reverses the order of -the commands. -
-Otherwise, fc invokes the editor named by -ename +

Similar to complete, but +replaces the word to be completed with a single match from +the list of possible completions. Repeatedly executing +menu−complete steps through the list of +possible completions, inserting each match in turn. At the +end of the list of completions, menu−complete +rings the bell (subject to the setting of +bell−style) and restores the original text. An +argument of n moves n positions forward in the +list of matches; a negative argument moves backward through +the list. This command is intended to be bound to +TAB, but is unbound by default.

-on a file containing those commands. -If -ename -is not supplied, fc uses the value of the -FCEDIT +

menu−complete−backward

- -variable, and -the value of -EDITOR +

Identical to +menu−complete, but moves backward through the +list of possible completions, as if +menu−complete had been given a negative +argument. This command is unbound by default.

- -if -FCEDIT - -is not set. -If neither variable is set, fc uses +

export−completions

-vi. +

Perform completion on the word +before point as described above and write the list of +possible completions to readline’s output +stream using the following format, writing information on +separate lines:

-When editing is complete, fc reads the file containing -the edited commands and echoes and executes them. -
-In the second form, fc re-executes command -after replacing each instance of pat with rep. -Command is interpreted the same as first above. -
-A useful alias to use with fc is + + + + + + + + + + + + + + + + + + + + + +
-so that typing -runs the last command beginning with +

•

 -and typing -re-executes the last command. -
-If the first form is used, the return value is zero unless an invalid -option is encountered or -first +

the number of matches N;

-or -last -specify history lines out of range. -When editing and re-executing a file of commands, -the return value is the value of the last command executed -or failure if an error occurs with the temporary file. -If the second form is used, the return status -is that of the re-executed command, unless -cmd +

•

 -does not specify a valid history entry, in which case -fc - -returns a non-zero status. -
fg [jobspec]
-Resume -jobspec - -in the foreground, and make it the current job. -If -jobspec - -is not present, fg uses the shell's notion of the current job. -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 -jobspec - -does not specify a valid job or -jobspec - -specifies a job that was started without job control. -
getopts optstring name [arg ...]
-getopts - -is used by shell scripts and functions to parse positional parameters -and obtain options and their arguments. -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, -getopts - -places the next option in the shell variable -name, - -initializing -name - -if it does not exist, -and the index of the next argument to be processed into the -variable -OPTIND. - - -OPTIND - - -is initialized to 1 each time the shell or a shell script -is invoked. -When an option requires an argument, -getopts -places that argument into the variable -OPTARG. - - -
-The shell does not reset -OPTIND - - -automatically; it must be manually reset between multiple -calls to -getopts - -within the same shell invocation to use a new set of parameters. -
-When it reaches the end of options, getopts exits with a -return value greater than zero. -OPTIND - - -is set to the index of the first non-option argument, -and name is set to ?. -
-getopts - -normally parses the positional parameters, but if more arguments are -supplied as -arg - -values, -getopts - -parses those instead. -
-getopts - -can report errors in two ways. -If the first character of -optstring - -is a colon, getopts uses -silent - -error reporting. -In normal operation, getopts prints diagnostic messages -when it encounters invalid options or missing option arguments. -If the variable -OPTERR - - -is set to 0, -getopts - -does not display any error messages, -even if the first character of -optstring - -is not a colon. -
-If -getopts - -detects an invalid option, it places ? into -name - -and, if not silent, -prints an error message and unsets -OPTARG. - - -If -getopts - -is silent, it assigns the option character found to -OPTARG - - -and does not print a diagnostic message. -
-If a required argument is not found, and -getopts - -is not silent, it sets the value of name to -a question mark (?), unsets -OPTARG, - - -and prints a diagnostic message. -If -getopts - -is silent, it sets the value of name to a colon (:) -and sets -OPTARG - - -to the option character found. -
-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. -
hash [-lr] [-p filename] [-dt] [name]
-Each time hash is invoked, it remembers -the full pathname of the command -name - -as determined by searching -the directories in -$PATH. - -Any previously-remembered pathname associated with name is discarded. -If the --p - -option is supplied, hash uses -filename - -as the full pathname of the command. -
-The --r - -option causes the shell to forget all -remembered locations. -Assigning to the PATH variable also clears all hashed filenames. -The --d - -option causes the shell to forget the remembered location of each name. -
-If the --t - -option is supplied, hash prints the full pathname corresponding to -each name. -If multiple name arguments are supplied with -t, -hash prints the name before the corresponding hashed -full pathname. -The --l - -option displays output in a format that may be reused as input. -
-If no arguments are given, or if only -l is supplied, -hash prints information about remembered commands. -The -t, -d, and -p options (the options that -act on the name arguments) are mutually exclusive. -Only one will be active. -If more than one is supplied, -t has higher priority than --p, and both have higher priority than -d. -
-The return status is zero unless a -name - -is not found or an invalid option is supplied. -
help [-dms] [pattern]
-Display helpful information about builtin commands. -If -pattern - -is specified, -help - -gives detailed help on all commands matching -pattern - -as described below; -otherwise it displays a list of -all the builtins and shell compound commands. -
-Options, if supplied, have the follow meanings: -
-
-
-
--d - -Display a short description of each pattern -
-m - -
-Display the description of each pattern in a manpage-like format -
-s - -
-Display only a short usage synopsis for each pattern - -
- -
-If pattern contains pattern matching characters -(see -Pattern Matching - - -above) -it's treated as a shell pattern and -help prints the description of each -help topic matching pattern. -
-If not, and pattern exactly matches the name of a help topic, -help prints the description -associated with that topic. -Otherwise, help performs prefix matching and -prints the descriptions of all matching help topics. -
-The return status is 0 unless no command matches -pattern. - -
history [n]
- -
history -c
-
history -d offset
-
history -d start-end
-
history -anrw [filename]
-
history -p arg [arg ...]
-
history -s arg [arg ...]
- -With no options, display the command history list with numbers. -Entries prefixed with a -* - -have been modified. -An argument of -n - -lists only the last -n - -entries. -If the shell variable -HISTTIMEFORMAT - - -is set and not null, -it is used as a format string for -strftime(3) - -to display the time stamp associated with each displayed history entry. -If -history - -uses -HISTTIMEFORMAT, - - -it does not print an intervening space between the formatted time stamp -and the history entry. -
-If filename is supplied, history uses it as the -name of the history file; if not, it uses the value of -HISTFILE. - - -If filename is not supplied and -HISTFILE - - -is unset or null, the -a, -n, -r, and -w options -have no effect. -
-Options, if supplied, have the following meanings: -
- -
-
-c - -
-Clear the history list by deleting all the entries. -This can be used with the other options to replace the history list. -
-d offset
-Delete the history entry at position offset. -If offset is negative, it is interpreted as relative to one greater -than the last history position, so negative indices count back from the -end of the history, and an index of -1 refers to the current -history -d command. -
-d start-end
-Delete the range of history entries between positions start and -end, inclusive. -Positive and negative values for start and end -are interpreted as described above. -
-a - -
-Append the - -history lines to the history file. -These are history lines entered since the beginning of the current -bash session, but not already appended to the history file. -
-n - -
-Read the history lines not already read from the history file -and add them to the current history list. -These are lines appended to the history file since the beginning of the -current bash session. -
-r - -
-Read the history file and append its contents to the current history list. -
-w - -
-Write the current history list to the history file, overwriting -the history file. -
-p - -
-Perform history substitution on the following args and display -the result on the standard output, -without storing the results in the history list. -Each arg must be quoted to disable normal history expansion. -
-s - -
-Store the -args - -in the history list as a single entry. -The last command in the -history list is removed before adding the -args. - - -
- -
-If the -HISTTIMEFORMAT - - -variable is set, history writes the time stamp information -associated with each history entry to the history file, -marked with the history comment character as described above. -When the history file is read, lines beginning with the history -comment character followed immediately by a digit are interpreted -as timestamps for the following history entry. -
-The return value is 0 unless an invalid option is encountered, an -error occurs while reading or writing the history file, an invalid -offset or range is supplied as an argument to -d, or the -history expansion supplied as an argument to -p fails. -
jobs [-lnprs] [ jobspec ... ]
- -
jobs -x command [ args ... ]
- -The first form lists the active jobs. -The options have the following meanings: -
- -
-
-l - -
-List process IDs in addition to the normal information. -
-n - -
-Display information only about jobs that have changed status since -the user was last notified of their status. -
-p - -
-List only the process ID of the job's process group leader. -
-r - -
-Display only running jobs. -
-s - -
-Display only stopped jobs. - -
- -
-If -jobspec +

the word being completed;

-is supplied, jobs restricts output to information about that job. -The return status is 0 unless an invalid option is encountered -or an invalid -jobspec - -is supplied. -
-If the --x -option is supplied, -jobs +

•

 -replaces any -jobspec -found in -command +

S:E, where S and E are the +start and end offsets of the word in the readline +line buffer; then

-or -args -with the corresponding process group ID, and executes -command, +

•

 -passing it -args, -returning its exit status. -
kill [-s sigspec | -n signum | -sigspec] id [ ... ]
+

each match, one per line

-
kill -l|-L [sigspec | exit_status]
+

If there are no +matches, the first line will be “0”, and this +command does not print any output after the +S:E. If there is only a single match, this +prints a single line containing it. If there is more than +one match, this prints the common prefix of the matches, +which may be empty, on the first line after the +S:E, then the matches on subsequent lines. In +this case, N will include the first line with the +common prefix.

-Send the signal specified by -sigspec +

The user or +application should be able to accommodate the possibility of +a blank line. The intent is that the user or application +reads N lines after the line containing +S:E to obtain the match list. This command is +unbound by default.

-or -signum -to the processes named by each -id. +

delete−char−or−list

-Each -id +

Deletes the character under the +cursor if not at the beginning or end of the line (like +delete−char). At the end of the line, it +behaves identically to possible−completions. +This command is unbound by default.

-may be a job specification jobspec -or a process ID pid. -sigspec +

complete−filename +(M−/)

-is either a case-insensitive signal name such as -SIGKILL - - -(with or without the -SIG +

Attempt filename completion on +the text before point.

- -prefix) or a signal number; -signum -is a signal number. -If -sigspec +

possible−filename−completions +(C−x /)

-is not supplied, then -kill +

List the possible completions +of the text before point, treating it as a filename.

-sends -SIGTERM. +

complete−username +(M−~)

- -
-The --l +

Attempt completion on the text +before point, treating it as a username.

-option lists the signal names. -If any arguments are supplied when --l -is given, -kill +

possible−username−completions +(C−x ~)

-lists the names of the signals corresponding to the arguments, -and the return status is 0. -The exit_status argument to --l +

List the possible completions +of the text before point, treating it as a username.

-is a number specifying either a signal number or the exit status of -a process terminated by a signal; -if it is supplied, kill prints the name of the signal that caused -the process to terminate. -kill assumes that process exit statuses are greater than 128; -anything less than that is a signal number. -The --L +

complete−variable +(M−$)

-option is equivalent to -l. -
-kill +

Attempt completion on the text +before point, treating it as a shell variable.

-returns true if at least one signal was successfully sent, or false -if an error occurs or an invalid option is encountered. -
let arg [arg ...]
-Each -arg -is evaluated as an arithmetic expression (see -ARITHMETIC EVALUATION +

possible−variable−completions +(C−x $)

- +

List the possible completions +of the text before point, treating it as a shell +variable.

-above). -If the last -arg +

complete−hostname +(M−@)

-evaluates to 0, -let +

Attempt completion on the text +before point, treating it as a hostname.

-returns 1; otherwise -let -returns 0. -
local [option] [name[=value] ... | - ]
-For each argument, create a local variable named -name +

possible−hostname−completions +(C−x @)

-and assign it -value. +

List the possible completions +of the text before point, treating it as a hostname.

-The option can be any of the options accepted by declare. -When -local +

complete−command +(M−!)

-is used within a function, it causes the variable -name +

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.

-to have a visible scope restricted to that function and its children. -It is an error to use -local - -when not within a function. -
-If name is -, it makes the set of shell options -local to the function in which local is invoked: -any shell options changed using the set builtin inside -the function after the call to local are restored to their -original values when the function returns. -The restore is performed as if a series of set commands were -executed to restore the values that were in place before the function. -
-With no operands, -local -writes a list of local variables to the standard output. -
-The return status is 0 unless -local +

possible−command−completions +(C−x !)

-is used outside a function, an invalid -name - -is supplied, or -name is a readonly variable. -
logout [n] - -
-Exit a login shell, -returning a status of n to the shell's parent. -
mapfile [-d delim] [-n count] [-O origin] [-s count] [-t] [-u fd] [-C callback] [-c quantum] [array]
- -
readarray [-d delim] [-n count] [-O origin] [-s count] [-t] [-u fd] [-C callback] [-c quantum] [array]
- -Read lines from the standard input, -or from file descriptor -fd - -if the --u - -option is supplied, -into the indexed array variable -array. - -The variable -MAPFILE - - -is the default array. -Options, if supplied, have the following meanings: -
- -
-
-d - -
-Use the first character of delim to terminate each input line, -rather than newline. -If delim is the empty string, mapfile will terminate a line -when it reads a NUL character. -
-n - -
-Copy at most -count - -lines. -If count is 0, copy all lines. -
-O +

List the possible completions +of the text before point, treating it as a command name.

-
-Begin assigning to -array - -at index -origin. - -The default index is 0. -
-s - -
-Discard the first count lines read. -
-t - -
-Remove a trailing delim (default newline) from each line read. -
-u - -
-Read lines from file descriptor fd instead of the standard input. -
-C - -
-Evaluate -callback - -each time quantum lines are read. -The -c option specifies -quantum. - -
-c - -
-Specify the number of lines read between each call to -callback. - - -
- -
-If --C - -is specified without --c, - -the default quantum is 5000. -When 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. -callback is evaluated after the line is read but before the -array element is assigned. -
-If not supplied with an explicit origin, mapfile will clear array -before assigning to it. -
-mapfile returns zero unless an invalid option or option -argument is supplied, array is invalid or unassignable, or if -array is not an indexed array. -
popd [-n] [+n] [-n]
-Remove entries from the directory stack. -The elements are numbered from 0 starting at the first directory -listed by dirs, so popd is equivalent to - -With no arguments, popd removes the top directory from the stack, -and changes to the new top directory. -Arguments, if supplied, have the following meanings: -
- -
-
-n - -
-Suppress the normal change of directory when removing directories -from the stack, only manipulate the stack. -
+n
-Remove the nth entry counting from the left of the list -shown by -dirs, - -starting with zero, from the stack. -For example: - -removes the first directory, - -the second. -
-n
-Remove the nth entry counting from the right of the list -shown by -dirs, - -starting with zero. For example: - -removes the last directory, - -the next to last. - -
- -
-If the top element of the directory stack is modified, and -the -n option was not supplied, popd uses the cd -builtin to change to the directory at the top of the stack. -If the cd fails, popd returns a non-zero value. -
-Otherwise, -popd - -returns false if an invalid option is supplied, the directory stack -is empty, or n specifies a non-existent directory stack entry. -
-If the -popd - -command is successful, -bash runs -dirs - -to show the final contents of the directory stack, -and the return status is 0. -
printf [-v var] format [arguments]
-Write the formatted arguments to the standard output under the -control of the format. -The -v option assigns the output to the variable -var rather than printing it to the standard output. -
-The format is a character string which contains three types of objects: -plain characters, which are simply copied to standard output, character -escape sequences, which are converted and copied to the standard output, and -format specifications, each of which causes printing of the next successive -argument. -In addition to the standard -printf(3) - -format characters -cCsSndiouxXeEfFgGaA, - -printf interprets the following additional format specifiers: -
- -
-
%b - -
-causes -printf to expand backslash escape sequences in the corresponding -argument -in the same way as echo -e. -
%q - -
-causes printf to output the corresponding -argument in a format that can be reused as shell input. -%q and %Q use the $'' quoting style if any characters -in the argument string require it, and backslash quoting otherwise. -If the format string uses the printf alternate form, these two -formats quote the argument string using single quotes. -
%Q - -
-like %q, but applies any supplied precision to the argument -before quoting it. -
%(datefmt)T - -
-causes printf to output the date-time string resulting from using -datefmt as a format string for -strftime(3). - -The corresponding argument is an integer representing the number of -seconds since the epoch. -This format specifier recognizes two special argument values: --1 represents the current time, -and -2 represents the time the shell was invoked. -If no argument is specified, conversion behaves as if -1 had been supplied. -This is an exception to the usual printf behavior. - -
- -
-The %b, %q, and %T format specifiers all use the field width and precision -arguments from the format specification and write that many bytes from -(or use that wide a field for) the expanded argument, which usually -contains more characters than the original. -
-The %n format specifier accepts a corresponding argument that is treated -as a shell variable name. -
-The %s and %c format specifiers accept an l (long) modifier, which forces -them to convert the argument string to a wide-character string and apply -any supplied field width and precision in terms of characters, not bytes. -The %S and %C format specifiers are equivalent to %ls and %lc, respectively. - - - -
-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 numeric value of -the following character, using the current locale. -
-The format is reused as necessary to consume all of the arguments. -If the format requires more arguments than are supplied, the -extra format specifications behave as if a zero value or null string, as -appropriate, had been supplied. -The return value is zero on success, -non-zero if an invalid option is supplied or a write or assignment error -occurs. -
pushd [-n] [+n] [-n]
- -
pushd [-n] [dir]
- -Add a directory to the top of the directory stack, or rotate -the stack, making the new top of the stack the current working -directory. -With no arguments, pushd exchanges the top two elements of -the directory stack. -Arguments, if supplied, have the following meanings: -
- -
-
-n - -
-Suppress the normal change of directory when rotating or -adding directories to the stack, only manipulate the stack. -
+n
-Rotate the stack so that the nth directory -(counting from the left of the list shown by -dirs, - -starting with zero) -is at the top. -
-n
-Rotates the stack so that the nth directory -(counting from the right of the list shown by -dirs, - -starting with zero) is at the top. -
dir - -
-Adds -dir - -to the directory stack at the top. - -
- -
-After the stack has been modified, if the -n option was not -supplied, pushd uses the cd builtin to change to the -directory at the top of the stack. -If the cd fails, pushd returns a non-zero value. -
-Otherwise, if no arguments are supplied, -pushd - -returns zero unless the directory stack is empty. -When rotating the directory stack, -pushd - -returns zero unless the directory stack is empty or -n specifies a non-existent directory stack element. -
-If the -pushd - -command is successful, -bash runs -dirs - -to show the final contents of the directory stack. -
pwd [-LP]
-Print the absolute pathname of the current working directory. -The pathname printed contains no symbolic links if the --P - -option is supplied or the --o physical - -option to the -set - -builtin command is enabled. -If the --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. -
read [-Eers] [-a aname] [-d delim] [-i text] [-n nchars] [-N nchars] [-p prompt] [-t timeout] [-u fd] [name ...]
-Read one line from the standard input, or from the file descriptor -fd supplied as an argument to the -u option, -split it into words as described - -above -under Word Splitting, -and assign the first word to the first -name, - -the second word to the second -name, - -and so on. -If there are more words than names, the remaining words and their -intervening delimiters are assigned to the last -name. - -If there are fewer words read from the input stream than names, -the remaining names are assigned empty values. -The characters in the value of the -IFS - - -variable -are used to split the line into words using the same rules the shell -uses for expansion (described - -above -under Word Splitting). -The backslash character (\) removes any special -meaning for the next character read and is used for line continuation. -
-Options, if supplied, have the following meanings: -
- -
-
-a aname - -
-The words are assigned to sequential indices of the array variable -aname, - -starting at 0. -aname - -is unset before any new values are assigned. -Other name arguments are ignored. -
-d delim - -
-The first character of delim terminates the input line, -rather than newline. -If delim is the empty string, read will terminate a line -when it reads a NUL character. -
-e - -
-If the standard input is coming from a terminal, -read uses -readline - -(see -READLINE - - - -above) -to obtain the line. -Readline uses the current -(or default, if line editing was not previously active) -editing settings, but uses readline's default filename completion. -
-E - -
-If the standard input is coming from a terminal, -read uses -readline - -(see -READLINE - - - -above) -to obtain the line. -Readline - -uses the current (or default, if line editing was not previously -active) editing settings, but uses bash's default completion, including -programmable completion. -
-i text - -
-If -readline - -is being used to read the line, read places text into -the editing buffer before editing begins. -
-n nchars - -
-read returns after reading nchars characters rather than -waiting for a complete line of input, -unless it encounters EOF or read times out, -but honors a delimiter if it reads fewer -than nchars characters before the delimiter. -
-N nchars - -
-read returns after reading exactly nchars characters rather -than waiting for a complete line of input, -unless it encounters EOF or read times out. -Any delimiter characters in the input are -not treated specially and do not cause read to return until -it has read nchars characters. -The result is not split on the characters in IFS; the intent is -that the variable is assigned exactly the characters read -(with the exception of backslash; see the -r option below). -
-p prompt - -
-Display prompt on standard error, without a -trailing newline, before attempting to read any input, but -only if input is coming from a terminal. -
-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 then be used as a line -continuation. -
-s - -
-Silent mode. -If input is coming from a terminal, characters are not echoed. -
-t timeout - -
-Cause read to time out and return failure if it does not read -a complete line of input (or a specified number of characters) -within timeout seconds. -timeout may be a decimal number with a fractional portion following -the decimal point. -This option is only effective if read is reading input from a -terminal, pipe, or other special file; it has no effect when reading -from regular files. -If read times out, it saves any partial input read into -the specified variable name, and the exit status is greater than 128. -If timeout is 0, read returns immediately, without trying to -read any data. -In this case, the exit status is 0 if input is available on the specified -file descriptor, or the read will return EOF, non-zero otherwise. -
-u fd - -
-Read input from file descriptor fd instead of the standard input. - -
- -
-Other than the case where delim is the empty string, read -ignores any NUL characters in the input. -
-If no -names - -are supplied, read assigns the line read, -without the ending delimiter but otherwise unmodified, -to the variable -REPLY. - - -
-The exit status is zero, unless end-of-file is encountered, read -times out (in which case the status is greater than 128), -a variable assignment error (such as assigning to a readonly variable) occurs, -or an invalid file descriptor is supplied as the argument to -u. -
readonly [-aAf] [-p] [name[=word] ...]
- -The given -names are marked readonly; the values of these -names - -may not be changed by subsequent assignment or unset. -If the --f - -option is supplied, each name refers to a shell function. -The --a - -option restricts the variables to indexed arrays; the --A - -option restricts the variables to associative arrays. -If both options are supplied, --A - -takes precedence. -If no -name - -arguments are supplied, or if the --p - -option is supplied, print a list of all readonly names. -The other options may be used to restrict the output to a subset of -the set of readonly names. -The --p - -option displays output in a format that may be reused as input. -
-readonly allows the value of a variable to be set at the same time -the readonly attribute is changed by following the variable name with -=value. -This sets the value of the variable is to value while modifying -the readonly attribute. -
-The return status is 0 unless an invalid option is encountered, -one of the -names - -is not a valid shell variable name, or --f - -is supplied with a -name - -that is not a function. -
return [n]
-Stop executing a shell function or sourced file and return the value -specified by -n - -to its caller. -If -n - -is omitted, the return status is that of the last command -executed. -If return is executed by a trap handler, the last command used to -determine the status is the last command executed before the trap handler. -If return is executed during a DEBUG trap, the last command -used to determine the status is the last command executed by the trap -handler before return was invoked. -
-When -return - -is used to terminate execution of a script being executed by the -. - -(source) command, it causes the shell to stop executing -that script and return either -n - -or the exit status of the last command executed within the -script as the exit status of the script. -If n is supplied, the return value is its least significant -8 bits. -
-Any command associated with the RETURN trap is executed -before execution resumes after the function or script. -
-The return status is non-zero if -return - -is supplied a non-numeric argument, or is used outside a -function and not during execution of a script by . or source. -
set [-abefhkmnptuvxBCEHPT] [-o option-name] [--] [-] [arg ...]
- -
set [+abefhkmnptuvxBCEHPT] [+o option-name] [--] [-] [arg ...]
-
set -o
-
set +o
- -Without options, display the name and value of each shell variable -in a format that can be reused as input -for setting or resetting the currently-set variables. -Read-only variables cannot be reset. -In posix mode, only shell variables are listed. -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 -$1, - -$2, - -..., -$n. - -Options, if specified, have the following meanings: -
- -
-
-a - -
-Each variable or function that is created or modified is given the -export attribute and marked for export to the environment of -subsequent commands. -
-b - -
-Report the status of terminated background jobs -immediately, rather than before the next primary prompt or after a -foreground command terminates. -This is effective only when job control is enabled. -
-e - -
- -Exit immediately if a -pipeline (which may consist of a single simple command), -a list, -or a compound command -(see -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 -while - -or -until - -reserved word, -part of the test following the -if - -or -elif - -reserved words, part of any command executed in a -&& - -or -|| - -list except the command following the final && or ||, -any command in a pipeline but the last -(subject to the state of the pipefail shell option), -or if the command's return value is -being inverted with -!. - -If a compound command other than a subshell -returns a non-zero status because a command failed -while -e was being ignored, the shell does not exit. -A trap on ERR, if set, is executed before the shell exits. -This option applies to the shell environment and each subshell environment -separately (see -COMMAND EXECUTION ENVIRONMENT - - - -above), -and may cause -subshells to exit before executing all the commands in the subshell. -
-If a compound command or shell function executes in a context -where -e is being ignored, -none of the commands executed within the compound command or function body -will be affected by the -e setting, even if -e is set -and a command returns a failure status. -If a compound command or shell function sets -e while executing in -a context where -e is ignored, that setting will not have any -effect until the compound command or the command containing the function -call completes. - -
-f - -
-Disable pathname expansion. -
-h - -
-Remember the location of commands as they are looked up for execution. -This is enabled by default. -
-k -
-All arguments in the form of assignment statements -are placed in the environment for a command, not just -those that precede the command name. -
-m +

dynamic−complete−history +(M−TAB)

-
-Monitor mode. -Job control is enabled. -This option is on by default for interactive shells on systems -that support it (see -JOB CONTROL +

Attempt completion on the text +before point, comparing the text against history list +entries for possible completion matches.

- +

dabbrev−expand

-above). -All processes run in a separate process group. -When a background job completes, the shell prints a line -containing its exit status. -
-n +

Attempt menu completion on the +text before point, comparing the text against lines from the +history list for possible completion matches.

-
-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. -
-o option-name -
-The option-name can be one of the following: -
-
-
allexport +

complete−into−braces +(M−{)

-
-Same as --a. +

Perform filename completion and +insert the list of possible completions enclosed within +braces so the list is available to the shell (see Brace +Expansion above).

-
braceexpand +

Keyboard Macros + +

-
-Same as --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 ---noediting +

start−kbd−macro +(C−x ()

-option. -This also affects the editing interface used for read -e. -
errexit +

Begin saving the characters +typed into the current keyboard macro.

-
-Same as --e. +

end−kbd−macro +(C−x ))

-
errtrace +

Stop saving the characters +typed into the current keyboard macro and store the +definition.

-
-Same as --E. -
functrace +

call−last−kbd−macro +(C−x e)

-
-Same as --T. +

Re-execute the last keyboard +macro defined, by making the characters in the macro appear +as if typed at the keyboard.

-
hashall -
-Same as --h. +

print−last−kbd−macro +()

-
histexpand +

Print the last keyboard macro +defined in a format suitable for the inputrc +file.

-
-Same as --H. +

Miscellaneous + +

-
history -
-Enable command history, as described -above -under -HISTORY. +

re−read−init−file +(C−x C−r)

- -This option is on by default in interactive shells. -
ignoreeof +

Read in the contents of the +inputrc file, and incorporate any bindings or +variable assignments found there.

-
-The effect is as if the shell command +

abort (C−g)

+

Abort the current editing +command and ring the terminal’s bell (subject to the +setting of bell−style).

-``IGNOREEOF=10'' +

do−lowercase−version +(M−A, M−B, M−x, +...)

+

If the metafied character +x is uppercase, run the command that is bound to the +corresponding metafied lowercase character. The behavior is +undefined if x is already lowercase.

+

prefix−meta +(ESC)

+

Metafy the next character +typed. ESC f is equivalent to +Meta−f.

+

undo (C−_, C−x +C−u)

-had been executed -(see -Shell Variables +

Incremental undo, separately +remembered for each line.

+

revert−line +(M−r)

-above). -
keyword +

Undo all changes made to this +line. This is like executing the undo command enough +times to return the line to its initial state.

-
-Same as --k. +

tilde−expand +(M−&)

-
monitor +

Perform tilde expansion on the +current word.

-
-Same as --m. +

set−mark (C−@, +M−<space>)

-
noclobber +

Set the mark to the point. If a +numeric argument is supplied, set the mark to that +position.

-
-Same as --C. -
noexec +

exchange−point−and−mark +(C−x C−x)

-
-Same as --n. +

Swap the point with the mark. +Set the current cursor position to the saved position, then +set the mark to the old cursor position.

-
noglob +

character−search +(C−])

-
-Same as --f. +

Read a character and move point +to the next occurrence of that character. A negative +argument searches for previous occurrences.

-
nolog -
-Currently ignored. -
notify +

character−search−backward +(M−C−])

-
-Same as --b. +

Read a character and move point +to the previous occurrence of that character. A negative +argument searches for subsequent occurrences.

-
nounset -
-Same as --u. +

skip−csi−sequence

-
onecmd +

Read enough characters to +consume a multi-key sequence such as those defined for keys +like Home and End. CSI sequences begin with a Control +Sequence Indicator (CSI), usually ESC [. If this +sequence is bound to “\e[”, keys producing CSI +sequences 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 [.

-
-Same as --t. +

insert−comment +(M−#)

-
physical +

Without a numeric argument, +insert the value of the readline comment−begin +variable at the beginning of the current line. If a numeric +argument is supplied, this command acts as a toggle: if the +characters at the beginning of the line do not match the +value of comment−begin, insert the value; +otherwise delete the characters in comment-begin from +the beginning of the line. In either case, the line is +accepted as if a newline had been typed. The default value +of comment−begin causes this command to make +the current line a shell comment. If a numeric argument +causes the comment character to be removed, the line will be +executed by the shell.

-
-Same as --P. -
pipefail +

spell−correct−word +(C−x s)

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

Perform spelling correction on +the current word, treating it as a directory or filename, in +the same way as the cdspell shell option. Word +boundaries are the same as those used by +shell−forward−word.

-
-Enable posix mode; -change the behavior of -bash -where the default operation differs -from the -POSIX -standard to match the standard. -See -SEE ALSO +

glob−complete−word +(M−g)

- +

Treat the word before point as +a pattern for pathname expansion, with an asterisk +implicitly appended, then use the pattern to generate a list +of matching file names for possible completions.

-below -for a reference to a document that details how posix mode affects -bash's behavior. -
privileged +

glob−expand−word +(C−x *)

-
-Same as --p. +

Treat the word before point as +a pattern for pathname expansion, and insert the list of +matching file names, replacing the word. If a numeric +argument is supplied, append a * before pathname +expansion.

-
verbose -
-Same as --v. +

glob−list−expansions +(C−x g)

-
vi +

Display the list of expansions +that would have been generated by +glob−expand−word and redisplay the line. +If a numeric argument is supplied, append a * before +pathname expansion.

+ +

dump−functions

+ +

Print all of the functions and +their key bindings to the readline output stream. If +a numeric argument is supplied, the output is formatted in +such a way that it can be made part of an inputrc +file.

+ +

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 inputrc file.

+ +

dump−macros

+ +

Print all of the +readline key sequences bound to macros and the +strings they output to the readline output stream. If +a numeric argument is supplied, the output is formatted in +such a way that it can be made part of an inputrc +file.

+ + +

execute−named−command +(M-x)

+ +

Read a bindable readline +command name from the input and execute the function to +which it’s bound, as if the key sequence to which it +was bound appeared in the input. If this function is +supplied with a numeric argument, it passes that argument to +the function it executes.

+ + +

display−shell−version +(C−x C−v)

+ +

Display version information +about the current instance of bash.

+ +

Programmable Completion + +

+ + +

When a user +attempts word completion for a command or an argument to a +command for which a completion specification (a +compspec) has been defined using the complete +builtin (see SHELL BUILTIN COMMANDS +below), readline invokes the programmable completion +facilities.

+ +

First, +bash identifies the command name. 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 the empty string (completion attempted +at the beginning of an empty line), bash uses any +compspec defined with the −E option to +complete. The −I option to +complete indicates that the command word is the first +non-assignment word on the line, or after a command +delimiter such as ; or |. This usually +indicates command name completion.

+ +

If the command +word is a full pathname, bash searches for a compspec +for the full pathname first. If there is no compspec for the +full pathname, bash attempts to find a compspec for +the portion following the final slash. If those searches do +not result in a compspec, or if there is no compspec for the +command word, bash uses any compspec defined with the +−D option to complete as the default. If +there is no default compspec, bash performs alias +expansion on the command word as a final resort, and +attempts to find a compspec for the command word resulting +from any successful expansion.

+ +

If a compspec is +not found, bash performs its default completion as +described above under Completing. Otherwise, once a +compspec has been found, bash uses it to generate the +list of matching words.

+ +

First, +bash performs the actions specified by the +compspec. This only returns matches which are prefixes of +the word being completed. When the −f or +−d option is used for filename or directory +name completion, bash uses the shell variable +FIGNORE to filter the matches.

+ +

Next, +programmable completion generates matches specified by a +pathname expansion pattern supplied as an argument to the +−G option. The words generated by the pattern +need not match the word being completed. Bash uses +the FIGNORE variable to filter the +matches, but does not use the +GLOBIGNORE shell variable.

+ +

Next, completion +considers the string specified as the argument to the +−W option. The string is first split using the +characters in the IFS special variable +as delimiters. This honors shell quoting within the string, +in order to provide a mechanism for the words to contain +shell metacharacters or characters in the value of +IFS. Each word is then +expanded using brace expansion, tilde expansion, parameter +and variable expansion, command substitution, and arithmetic +expansion, as described above under +EXPANSION. The results +are split using the rules described above under Word +Splitting. The results of the expansion are +prefix-matched against the word being completed, and the +matching words become possible completions.

+ +

After these +matches have been generated, bash executes any shell +function or command specified with the −F and +−C options. When the command or function is +invoked, bash assigns values to the +COMP_LINE, COMP_POINT, +COMP_KEY, and COMP_TYPE +variables as described above under Shell Variables. +If a shell function is being invoked, bash also sets +the COMP_WORDS and +COMP_CWORD variables. When the +function or command is invoked, the first argument +($1) is the name of the command whose arguments are +being completed, the second argument ($2) is the word +being completed, and the third argument ($3) is the +word preceding the word being completed on the current +command line. There is no filtering of the generated +completions against the word being completed; the function +or command has complete freedom in generating the matches +and they do not need to match a prefix of the word.

+ +

Any function +specified with −F is invoked first. The +function may use any of the shell facilities, including the +compgen and compopt builtins described below, +to generate the matches. It must put the possible +completions in the COMPREPLY array +variable, one per array element.

+ +

Next, any +command specified with the −C option is invoked +in an environment equivalent to command substitution. It +should print a list of completions, one per line, to the +standard output. Backslash will escape a newline, if +necessary. These are added to the set of possible +completions.

+ +

External +commands that are invoked to generate completions ( +“external completers”) receive the word +preceding the completion word as an argument, as described +above. This provides context that is sometimes useful, but +may include information that is considered sensitive or part +of a word expansion that will not appear in the command line +after expansion. That word may be visible in process +listings or in audit logs. This may be a concern to users +and completion specification authors if there is sensitive +information on the command line before expansion, since +completion takes place before words are expanded. If this is +an issue, completion authors should use functions as +wrappers around external commands and pass context +information to the external command in a different way. +External completers can infer context from the +COMP_LINE and +COMP_POINT environment variables, but +they need to ensure they break words in the same way +readline does, using the +COMP_WORDBREAKS variable.

+ +

After generating +all of the possible completions, bash applies any +filter specified with the −X option to the +completions in the list. The filter is a pattern as used for +pathname expansion; a & in the pattern is +replaced with the text of the word being completed. A +literal & may be escaped with a backslash; the +backslash is removed before attempting a match. Any +completion that matches the pattern is removed from the +list. A leading ! negates the pattern; in this case +bash removes any completion that does not match the +pattern. If the nocasematch shell option is enabled, +bash performs the match without regard to the case of +alphabetic characters.

+ +

Finally, +programmable completion adds any prefix and suffix specified +with the −P and −S options, +respectively, to each completion, and returns the result to +readline as the list of possible completions.

+ +

If the +previously-applied actions do not generate any matches, and +the −o dirnames option was supplied to +complete when the compspec was defined, bash +attempts directory name completion.

+ +

If the +−o plusdirs option was supplied to +complete when the compspec was defined, bash +attempts directory name completion and adds any matches to +the set of possible completions.

+ +

By default, if a +compspec is found, whatever it generates is returned to the +completion code as the full set of possible completions. The +default bash completions and the readline +default of filename completion are disabled. If the +−o bashdefault option was supplied to +complete when the compspec was defined, and the +compspec generates no matches, bash attempts its +default completions. If the compspec and, if attempted, the +default bash completions generate no matches, and the +−o default option was supplied to +complete when the compspec was defined, programmable +completion performs readline’s default +completion.

+ +

The options +supplied to complete and compopt can control +how readline treats the completions. For instance, +the −o fullquote option tells readline +to quote the matches as if they were filenames. See the +description of complete below for details.

+ +

When a compspec +indicates that it wants directory name completion, the +programmable completion functions force readline to +append a slash to completed names which are symbolic links +to directories, subject to the value of the +mark−directories readline variable, regardless +of the setting of the mark-symlinked−directories +readline variable.

+ +

There is some +support for dynamically modifying completions. This is most +useful when used in combination with a default completion +specified with complete −D. It’s possible +for shell functions executed as completion functions 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 can be used to +build a set of completions dynamically as completion is +attempted, rather than loading them all at once.

+ +

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:

+ +

_completion_loader()
+{
+. "/etc/bash_completion.d/$1.sh" \
+>/dev/null 2>&1 && return 124
+}
+complete −D −F _completion_loader \
+−o bashdefault −o default

+ +

HISTORY + +

+ + +

When the +−o history option to the set builtin is +enabled, the shell provides access to the command +history, the list of commands previously typed. The +value of the HISTSIZE variable is used +as the number of commands to save in a history list: the +shell saves the text of the last +HISTSIZE commands (default 500). The +shell stores each command in the history list prior to +parameter and variable expansion (see +EXPANSION above) but after history +expansion is performed, subject to the values of the shell +variables HISTIGNORE and +HISTCONTROL.

+ +

On startup, +bash initializes the history list by reading history +entries from the file named by the +HISTFILE variable (default +~/.bash_history). That file is referred to as the +history file. The history file is truncated, if +necessary, to contain no more than the number of history +entries specified by the value of the +HISTFILESIZE variable. If +HISTFILESIZE is unset, or set to null, +a non-numeric value, or a numeric value less than zero, the +history file is not truncated.

+ +

When the history +file is read, lines beginning with the history comment +character followed immediately by a digit are interpreted as +timestamps for the following history line. These timestamps +are optionally displayed depending on the value of the +HISTTIMEFORMAT variable. When present, +history timestamps delimit history entries, making +multi-line entries possible.

+ +

When a shell +with history enabled exits, bash copies the last +$HISTSIZE entries from the history +list to $HISTFILE. If +the histappend shell option is enabled (see the +description of shopt under SHELL BUILTIN +COMMANDS below), bash appends the entries +to the history file, otherwise it overwrites the history +file. If HISTFILE is unset or null, or +if the history file is unwritable, the history is not saved. +After saving the history, bash truncates the history +file to contain no more than +HISTFILESIZE lines as described +above.

+ +

If the +HISTTIMEFORMAT variable is set, the +shell writes the timestamp information associated with each +history entry to the history file, marked with the history +comment character, so timestamps are preserved across shell +sessions. This uses the history comment character to +distinguish timestamps from other history lines. As above, +when using +HISTTIMEFORMAT, the +timestamps delimit multi-line history entries.

+ +

The fc +builtin command (see SHELL BUILTIN +COMMANDS below) will list or edit and re-execute +a portion of the history list. The history builtin +can 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.

+ +

The shell allows +control over which commands are saved on the history list. +The HISTCONTROL and +HISTIGNORE variables are used to save +only a subset of the commands entered. If the cmdhist +shell option is enabled, the shell attempts to save each +line of a multi-line command in the same history entry, +adding semicolons where necessary to preserve syntactic +correctness. The lithist shell option modifies +cmdhist by saving the command with embedded newlines +instead of semicolons. See the description of the +shopt builtin below under SHELL BUILTIN +COMMANDS for information on setting and +unsetting shell options.

+ +

HISTORY EXPANSION + +

+ + +

The shell +supports a history expansion feature that is similar to the +history expansion in csh. This section describes what +syntax features are available.

+ +

History +expansion is enabled by default for interactive shells, and +can be disabled using the +H option to the set +builtin command (see SHELL BUILTIN +COMMANDS below). Non-interactive shells do not +perform history expansion by default, but it can be enabled +with “set -H”.

+ +

History +expansions introduce words from the history list into the +input stream, making it easy to repeat commands, insert the +arguments to a previous command into the current input line, +or fix errors in previous commands quickly.

+ +

History +expansion is performed immediately after a complete line is +read, before the shell breaks it into words, and is +performed on each line individually. The shell attempts to +inform the history expansion functions about quoting still +in effect from previous lines.

+ +

It takes place +in two parts. The first is to determine which history list +entry to use during substitution. The second is to select +portions of that entry to include into the current one.

+ +

The entry +selected from the history is the event, and the +portions of that entry that are acted upon are words. +Various modifiers are available to manipulate the +selected words. The entry is split into words in the same +fashion as when reading input, so that several +metacharacter-separated words surrounded by quotes +are considered one word. The event designator selects +the event, the optional word designator selects words +from the event, and various optional modifiers are +available to manipulate the selected words.

+ +

History +expansions are introduced by the appearance of the history +expansion character, which is ! by default. History +expansions may appear anywhere in the input, but do not +nest.

+ +

Only backslash +(\) and single quotes can quote the history expansion +character, but the history expansion character is also +treated as quoted if it immediately precedes the closing +double quote in a double-quoted string.

+ +

Several +characters inhibit history expansion if found immediately +following the history expansion character, even if it is +unquoted: space, tab, newline, carriage return, =, +and the other shell metacharacters defined above.

+ +

There is a +special abbreviation for substitution, active when the +quick substitution character (described above under +histchars) is the first character on the line. It +selects the previous history list entry, using an event +designator equivalent to !!, and substitutes one +string for another in that entry. It is described below +under Event Designators. This is the only history +expansion that does not begin with the history expansion +character.

+ +

Several shell +options settable with the shopt builtin will modify +history expansion behavior (see the description of the +shopt builtin below).and If the histverify +shell option is enabled, and readline is being used, +history substitutions are not immediately passed to the +shell parser. Instead, the expanded line is reloaded into +the readline editing buffer for further modification. +If readline is being used, and the histreedit +shell option is enabled, a failed history substitution is +reloaded into the readline editing buffer for +correction.

+ +

The +−p option to the history builtin command +shows what a history expansion will do before using it. The +−s option to the history builtin will +add commands to the end of the history list without actually +executing them, so that they are available for subsequent +recall.

+ +

The shell allows +control of the various characters used by the history +expansion mechanism (see the description of histchars +above under Shell Variables). The shell uses the +history comment character to mark history timestamps when +writing the history file.

+ +

Event Designators + +

+ + +

An event +designator is a reference to an entry in the history list. +The event designator consists of the portion of the word +beginning with the history expansion character and ending +with the word designator if present, or the end of the word. +Unless the reference is absolute, events are relative to the +current position in the history list.

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

!

 + + +

Start a history substitution, except when followed by a +blank, newline, carriage return, =, or, when the +extglob shell option is enabled using the +shopt builtin, (.

+ + +

!n

 + + +

Refer to history list entry n.

+ + +

!−n

 + + +

Refer to the current entry minus n.

+ + +

!!

 -
-Use a vi-style command line editing interface. -This also affects the editing interface used for read -e. -
xtrace -
-Same as --x. +

Refer to the previous entry. This is a synonym for +“!−1”.

-
-

+

!string

-If --o +

Refer to the most recent +command preceding the current position in the history list +starting with string.

-is supplied with no option-name, -set prints the current shell option settings. -If -+o -is supplied with no option-name, -set prints a series of -set +

!?string[?]

-commands to recreate the current option settings -on the standard output. -
+

Refer to the most recent +command preceding the current position in the history list +containing string. The trailing ? may be +omitted if string is followed immediately by a +newline. If string is missing, this uses the string +from the most recent search; it is an error if there is no +previous search string.

-
-p +

^ +string1 ^ string2 +^

-
-Turn on -privileged +

Quick substitution. Repeat the +previous command, replacing string1 with +string2. Equivalent to “!!:s ^ +string1 ^ string2 ^ +” (see Modifiers below).

-mode. In this mode, the shell does not read the -$ENV + + + + + + + +
- -and -$BASH_ENV - -files, shell functions are not inherited from the -environment, and the -SHELLOPTS, +

!#

 - -BASHOPTS, - -CDPATH, +

The entire command line typed so far.

 +
- -and -GLOBIGNORE +

Word Designators + +

- -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 -p option is not supplied, these actions -are taken and the effective user id is set to the real user id. -If the -p option is supplied at startup, the effective user id is -not reset. -Turning this option off causes the effective user -and group ids to be set to the real user and group ids. -
-r -
-Enable restricted shell mode. -This option cannot be unset once it has been set. -
-t +

Word designators +are used to select desired words from the event. They are +optional; if the word designator isn’t supplied, the +history expansion uses the entire event. A : +separates the event specification from the word designator. +It may be omitted if the word designator begins with a +^, $, *, −, or %. +Words are numbered from the beginning of the line, with the +first word being denoted by 0 (zero). Words are inserted +into the current line separated by single spaces.
+0 (zero)

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

The zeroth word. For the shell, +this is the command word.

-
-Treat unset variables and parameters other than the special -parameters + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
-and -or array variables subscripted with +

n

 -or -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. -
-v +

The nth word.

-
-Print shell input lines as they are read. -
-x -
-After expanding each simple command, -for command, case command, select command, or -arithmetic for command, display the expanded value of -PS4, +

^

 - -followed by the command and its expanded arguments -or associated word list, to the standard error. -
-B -
-The shell performs brace expansion (see -Brace Expansion +

The first argument: word 1.

-above). -This is on by default. -
-C +

$

 -
-If set, -bash -does not overwrite an existing file with the ->, +

The last word. This is usually the last argument, but +will expand to the zeroth word if there is only one word in +the line.

->&, -and -<> +

%

 -redirection operators. -Using the redirection operator ->| -instead of -> +

The first word matched by the most recent +“?string?” search, if the search string +begins with a character that is part of a word. By default, +searches begin at the end of each line and proceed to the +beginning, so the first word matched is the one closest to +the end of the line.

-will override this and force the creation of an output file. -
-E -
-If set, any trap on ERR is inherited by shell functions, command -substitutions, and commands executed in a subshell environment. -The ERR trap is normally not inherited in such cases. -
-H +

x−y

 -
-Enable -! -style history substitution. -This option is on by default when the shell is interactive. -
-P +

A range of words; “−y” +abbreviates “0−y”.

-
-If set, the shell does not resolve symbolic links when executing -commands such as -cd -that change the current working directory. -It uses the physical directory structure instead. -By default, -bash +

*

 -follows the logical chain of directories when performing commands -which change the current directory. -
-T -
-If set, any traps on DEBUG and RETURN are inherited by shell -functions, command substitutions, and commands executed in a -subshell environment. -The DEBUG and RETURN traps are normally not inherited -in such cases. -
-- - -
-If no arguments follow this option, unset the positional parameters. -Otherwise, set the positional parameters to the -args, even if some of them begin with a --. - -
- - -
-Signal the end of options, and assign all remaining args to -the positional parameters. -The --x - -and --v - -options are turned off. -If there are no args, the positional parameters remain unchanged. - - -

- -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 -$-. +

All of the words but the zeroth. This is a synonym for +“1−$”. It is not an error to use +* if there is just one word in the event; it expands +to the empty string in that case.

-The return status is always zero unless an invalid option is encountered. - -
shift [n]
-Rename positional parameters from n+1 ... to -$1 - -.... - -Parameters represented by the numbers $# -down to $#-n+1 are unset. -n +

x*

 -must be a non-negative number less than or equal to $#. -If -n -is 0, no parameters are changed. -If -n - -is not given, it is assumed to be 1. -If -n - -is greater than $#, the positional parameters are not changed. -The return status is greater than zero if -n - -is greater than -$# - -or less than zero; otherwise 0. -
shopt [-pqsu] [-o] [optname ...]
-Toggle the values of settings controlling optional shell behavior. -The settings can be either those listed below, or, if the --o - -option is used, those available with the --o - -option to the set builtin command. -
-With no options, or with the --p - -option, display a list of all settable options, with -an indication of whether or not each is set; -if any optnames are supplied, the output is restricted to those options. -The -p option displays output in a form that -may be reused as input. -
-Other options have the following meanings: -
- -
-
-s - -
-Enable (set) each optname. -
-u - -
-Disable (unset) each optname. -
-q - -
-Suppresses normal output (quiet mode); the return status indicates -whether the optname is set or unset. -If multiple optname arguments are supplied with --q, - -the return status is zero if all optnames are enabled; non-zero -otherwise. -
-o - -
-Restricts the values of optname to be those defined for the --o - -option to the -set - -builtin. - -
-

- -If either --s - -or --u - -is used with no optname arguments, -shopt - -shows only those options which are set or unset, respectively. -Unless otherwise noted, the shopt options are disabled (unset) -by default. -

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

- -The list of shopt options is: -

- - -

-
array_expand_once - -
-If set, the shell suppresses multiple evaluation of -associative and indexed array subscripts -during arithmetic expression evaluation, while executing -builtins that can perform variable assignments, -and while executing builtins that perform array dereferencing. -
assoc_expand_once - -
-Deprecated; a synonym for array_expand_once. -
autocd - -
-If set, a command name that is the name of a directory is executed as if -it were the argument to the cd command. -This option is only used by interactive shells. -
bash_source_fullpath - -
-If set, filenames added to the BASH_SOURCE array variable are -converted to full pathnames (see Shell Variables above). -
cdable_vars - -
-If set, an argument to the -cd - -builtin command that -is not a directory is assumed to be the name of a variable whose -value is the directory to change to. -
cdspell +

Abbreviates x−$.

-
-If set, the -cd -command attempts to correct -minor errors in the spelling of a directory component. -Minor errors include transposed characters, -a missing character, and one extra character. -If cd corrects the directory name, it prints the corrected filename, -and the command proceeds. -This option is only used by interactive shells. -
checkhash - -
-If set, bash checks that a command found in the hash -table exists before trying to execute it. -If a hashed command no longer exists, bash performs a normal path search. -
checkjobs - -
-If set, bash lists the status of any stopped and running jobs before -exiting an interactive shell. -If any jobs are running, bash defers the exit until a second -exit is attempted without an intervening command (see -JOB CONTROL - - - -above). -The shell always postpones exiting if any jobs are stopped. -
checkwinsize - -
-If set, bash checks the window size after each external (non-builtin) -command -and, if necessary, updates the values of -LINES - - -and -COLUMNS, - - -using the file descriptor associated with the standard error -if it is a terminal. -This option is enabled by default. -
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. -This option is enabled by default, but only has an effect if command -history is enabled, as described +

x−

 -above -under -HISTORY. - +

Abbreviates x−$ like x*, but omits +the last word. If x is missing, it defaults to 0.

-
compat31 - -
-
compat32 - -
-
compat40 +

If a word +designator is supplied without an event specification, the +previous command is used as the event, equivalent to +!!.

-
-
compat41 +

Modifiers + +

-
-
compat42 -
-
compat43 +

After the +optional word designator, the expansion may include a +sequence of one or more of the following modifiers, each +preceded by a “:”. These modify, or edit, the +word or words selected from the history event.

-
-
compat44 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
-
-These control aspects of the shell's compatibility mode -(see -SHELL COMPATIBILITY MODE +

h

 - -below). +

Remove a trailing pathname +component, leaving only the head.

-
complete_fullquote - -
-If set, -bash -quotes all shell metacharacters in filenames and directory names when -performing completion. -If not set, -bash - -removes metacharacters such as the dollar sign from the set of -characters that will be quoted in completed filenames -when these metacharacters appear in shell variable references in words to be -completed. -This means that dollar signs in variable names that expand to directories -will not be quoted; -however, any dollar signs appearing in filenames will not be quoted, either. -This is active only when bash is using backslashes to quote completed -filenames. -This variable is set by default, which is the default bash behavior in -versions through 4.2. -
direxpand +

t

 -
-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 +

Remove all leading pathname components, leaving the +tail.

-attempts to preserve what the user typed. -
dirspell -
-If set, -bash +

r

 -attempts spelling correction on directory names during word completion -if the directory name initially supplied does not exist. -
dotglob -
-If set, -bash +

Remove a trailing suffix of the form .xxx, +leaving the basename.

-includes filenames beginning with a -in the results of pathname expansion. -The filenames +

e

 -. -and +

Remove all but the trailing suffix.

-.. -must always be matched explicitly, even if -dotglob +

p

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

Print the new command but do not execute it.

-builtin. -An interactive shell does not exit if -exec - -fails. -
expand_aliases -
-If set, aliases are expanded as described +

q

 -above -under -ALIASES. - - -This option is enabled by default for interactive shells. -
extdebug - -
-If set at shell invocation, or in a shell startup file, -arrange to execute the debugger profile -before the shell starts, identical to the --debugger option. -If set after invocation, behavior intended for use by debuggers is enabled: -
-
-
1. - -
-The -F option to the declare builtin displays the source -file name and line number corresponding to each function name supplied -as an argument. -
2. - -
-If the command run by the DEBUG trap returns a non-zero value, the -next command is skipped and not executed. -
3. - -
-If the command run by the DEBUG trap returns a value of 2, and the -shell is executing in a subroutine (a shell function or a shell script -executed by the . or source builtins), the shell simulates -a call to return. -
4. -
-BASH_ARGC +

Quote the substituted words, escaping further +substitutions.

- -and -BASH_ARGV - -are updated as described in their descriptions +

x

 -above). -
5. -
-Function tracing is enabled: command substitution, shell functions, and -subshells invoked with ( command ) inherit the -DEBUG and RETURN traps. -
6. +

Quote the substituted words as with q, but break +into words at blanks and newlines. The q and +x modifiers are mutually exclusive; expansion uses +the last one supplied.

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

s/old/new/

-
-If set, enable the extended pattern matching features described +

Substitute new for the +first occurrence of old in the event line. Any +character may be used as the delimiter in place of /. The +final delimiter is optional if it is the last character of +the event line. A single backslash quotes the delimiter in +old and new. If & appears in new, +it is replaced with old. A single backslash quotes +the &. If old is null, it is set to the last +old substituted, or, if no previous history +substitutions took place, the last string in a +!?string[?] search. If new is +null, each matching old is deleted.

-above -under -Pathname Expansion. -
extquote + + + + + + + + + + + + + + + + +
-
-If set, $'string' and $" -string" - quoting is -performed within ${parameter} expansions -enclosed in double quotes. -This option is enabled by default. -
failglob - -
-If set, patterns which fail to match filenames during pathname expansion -result in an expansion error. -
force_fignore - -
-If set, the suffixes specified by the -FIGNORE - - -shell variable -cause words to be ignored when performing word completion even if -the ignored words are the only possible completions. -See -Shell Variables - - -above -for a description of -FIGNORE. - - -This option is enabled by default. -
globasciiranges - -
-If set, range expressions used in pattern matching bracket expressions (see -Pattern Matching - - - -above) -behave as if in the traditional C locale when performing comparisons. -That is, pattern matching does not take -the current locale's collating sequence into account, so -b - -will not collate between -A - -and -B, -and upper-case and lower-case ASCII characters will collate together. -
globskipdots - -
-If set, pathname expansion will never match the filenames +

&

 -. - -and -.., +

Repeat the previous substitution.

-even if the pattern begins with a -This option is enabled by default. -
globstar - -
-If set, the pattern ** used in a pathname expansion context will -match all files and zero or more directories and subdirectories. -If the pattern is followed by a /, only directories and -subdirectories match. -
gnu_errfmt - -
-If set, shell error messages are written in the standard GNU error -message format. -
histappend - -
-If set, the history list is appended to the file named by the value -of the -HISTFILE - - -variable when the shell exits, rather than overwriting the file. -
histreedit +

g

 -
-If set, and -readline - -is being used, the user is given the opportunity to re-edit a -failed history substitution. -
histverify - -
-If set, and -readline - -is being used, the results of history substitution are not immediately -passed to the shell parser. -Instead, the resulting line is loaded into the readline editing buffer, -allowing further modification. -
hostcomplete -
-If set, and -readline +

Cause changes to be applied over the entire event line. +This is used in conjunction with “:s” +(e.g., +“:gs/old/new/”) +or “:&”. If used with +“:s”, 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 a may be used as a +synonym for g.

+ + +

G

 + + +

Apply the following “s” or +“&” modifier once to each word in the +event line.

+ +

SHELL BUILTIN COMMANDS + +

+ + +

Unless otherwise +noted, each builtin command documented in this section as +accepting options preceded by − accepts +−− to signify the end of the options. The +:, true, false, and +test/[ builtins do not accept options and do +not treat −− specially. The exit, +logout, return, break, continue, +let, and shift builtins accept and process +arguments beginning with − without requiring +−−. Other builtins that accept arguments +but are not specified as accepting options interpret +arguments beginning with − as invalid options +and require −− to prevent this +interpretation.
+: [arguments]

+ +

No effect; the command does +nothing beyond expanding arguments and performing any +specified redirections. The return status is zero.

+ +

. [−p +path] filename [arguments]
+source [−p path] filename +[arguments]

+ +

The . command +(source) reads and execute commands from +filename in the current shell environment and returns +the exit status of the last command executed from +filename.

+ +

If +filename does not contain a slash, . searches +for it. If the −p option is supplied, . +treats path as a colon-separated list of directories +in which to find filename; otherwise, . uses +the entries in PATH to find the +directory containing filename. filename does +not need to be executable. When bash is not in posix +mode, it searches the current directory if filename +is not found in PATH, +but does not search the current directory if −p +is supplied. If the sourcepath option to the +shopt builtin command is turned off, . does +not search PATH.

+ +

If any +arguments are supplied, they become the positional +parameters when filename is executed. Otherwise the +positional parameters are unchanged.

+ +

If the +−T option is enabled, . inherits any +trap on DEBUG; if it is not, any DEBUG trap +string is saved and restored around the call to ., +and . unsets the DEBUG trap while it executes. +If −T is not set, and the sourced file changes +the DEBUG trap, the new value persists after . +completes. The return status is the status of the last +command executed from filename (0 if no commands are +executed), and non-zero if filename is not found or +cannot be read.

+ +

alias [−p] +[name[=value] ...]

+ +

With no arguments or with the +−p option, alias prints the list of +aliases in the form alias name=value on +standard output. When arguments are supplied, define an +alias for each name whose value is given. A +trailing space in value causes the next word to be +checked for alias substitution when the alias is expanded +during command parsing. For each name in the argument +list for which no value is supplied, print the name +and value of the alias name. alias returns +true unless a name is given (without a corresponding +=value) for which no alias has been defined.

+ +

bg [jobspec +...]

+ +

Resume each suspended job +jobspec in the background, as if it had been started +with &. If jobspec is not present, the +shell uses its notion of the current job. bg +jobspec returns 0 unless run when job control is +disabled or, when run with job control enabled, any +specified jobspec was not found or was started +without job control.

+ +

bind [−m +keymap] [−lsvSVX]
+bind [−m keymap] [−q +function] [−u function] +[−r keyseq]
+bind [−m keymap] −f +filename
+bind [−m keymap] −x +keyseq[:] shell−command
+bind [−m keymap] +keyseq:function−name
+bind [−m keymap] +−p|−P +[readline−command]
+bind [−m keymap] +keyseq:readline−command
+bind readline-command-line

+ +

Display current readline +key and function bindings, bind a key sequence to a +readline function or macro or to a shell command, or +set a readline variable. Each non-option argument is +a key binding or command as it would appear in a +readline initialization file such as .inputrc, +but each binding or command must be passed as a separate +argument; e.g., '"\C−x\C−r": +re−read−init−file'. In the following +descriptions, output available to be re-read is formatted as +commands that would appear in a readline +initialization file or that would be supplied as individual +arguments to a bind command. Options, if supplied, +have the following meanings:
+−m keymap

-is being used, bash will attempt to perform hostname completion when a -word containing a @ is being completed (see -Completing +

Use keymap as the keymap +to be affected by the subsequent bindings. Acceptable +keymap names are emacs, emacs−standard, +emacs−meta, emacs−ctlx, vi, vi−move, +vi−command, and vi−insert. vi +is equivalent to vi−command +(vi−move is also a synonym); emacs is +equivalent to emacs−standard.

-under -READLINE + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
- -above). -This is enabled by default. -
huponexit +

−l

 -
-If set, bash will send -SIGHUP - -to all jobs when an interactive login shell exits. -
inherit_errexit +

List the names of all readline functions.

-
-If set, command substitution inherits the value of the errexit option, -instead of unsetting it in the subshell environment. -This option is enabled when posix mode is enabled. -
interactive_comments -
-In an interactive shell, a word beginning with # -causes that word and all remaining characters on that -line to be ignored, as in a non-interactive shell -(see -COMMENTS +

−p

 - -above). -This option is enabled by default. -
lastpipe +

Display readline function names and bindings in +such a way that they can be used as an argument to a +subsequent bind command or in a readline +initialization file. If arguments remain after option +processing, bind treats them as readline +command names and restricts output to those names.

-
-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. -
lithist -
-If set, and the -cmdhist +

−P

 -option is enabled, multi-line commands are saved to the history with -embedded newlines rather than using semicolon separators where possible. -
localvar_inherit - -
-If set, local variables inherit the value and attributes of a variable of -the same name that exists at a previous scope before any new value is -assigned. -The nameref attribute is not inherited. -
localvar_unset - -
-If set, calling unset on local variables in previous function scopes -marks them so subsequent lookups find them unset until that function -returns. -This is identical to the behavior of unsetting local variables at the -current function scope. -
login_shell - -
-The shell sets this option if it is started as a login shell (see -INVOCATION - - - -above). -The value may not be changed. -
mailwarn - -
-If set, and a file that bash is checking for mail has been -accessed since the last time it was checked, -bash displays the message - -
no_empty_cmd_completion - -
-If set, and -readline - -is being used, -bash - -does not search -PATH - - -for possible completions when completion is attempted on an empty line. -
nocaseglob - -
-If set, -bash - -matches filenames in a case-insensitive fashion when performing pathname -expansion (see -Pathname Expansion - - -above). -
nocasematch - -
-If set, -bash - -matches patterns in a case-insensitive fashion when performing matching -while executing case or [[ conditional commands, -when performing pattern substitution word expansions, -or when filtering possible completions as part of programmable completion. -
noexpand_translation - -
-If set, -bash - -encloses the translated results of -$ ... - -quoting in single quotes instead of double quotes. -If the string is not translated, this has no effect. -
nullglob -
-If set, pathname expansion patterns which match no files -(see -Pathname Expansion - - -above) -expand to nothing and are removed, rather than expanding to themselves. -
patsub_replacement - -
-If set, bash -expands occurrences of & in the replacement string of pattern -substitution to the text matched by the pattern, as described -under Parameter Expansion +

List current readline function names and +bindings. If arguments remain after option processing, +bind treats them as readline command names and +restricts output to those names.

+ + +

−s

 + + +

Display readline key sequences bound to macros +and the strings they output in such a way that they can be +used as an argument to a subsequent bind command or +in a readline initialization file.

+ + +

−S

 + + +

Display readline key sequences bound to macros +and the strings they output.

+ + +

−v

 + + +

Display readline variable names and values in +such a way that they can be used as an argument to a +subsequent bind command or in a readline +initialization file.

+ -above. -This option is enabled by default. -
progcomp +

−V

 + + +

List current readline variable names and +values.

+ +

−f +filename

-
-If set, enable the programmable completion facilities (see -Programmable Completion +

Read key bindings from +filename.

-above). -This option is enabled by default. -
progcomp_alias +

−q +function

-
-If set, and programmable completion is enabled, bash treats a command -name that doesn't have any completions as a possible alias and attempts -alias expansion. -If it has an alias, bash attempts programmable -completion using the command word resulting from the expanded alias. -
promptvars +

Display key sequences that +invoke the named readline function.

+ +

−u +function

+ +

Unbind all key sequences bound +to the named readline function.

+ +

−r +keyseq

+ +

Remove any current binding for +keyseq.

+ +

−x +keyseq[: ]shell−command

+ +

Cause +shell−command to be executed whenever +keyseq is entered. The separator between +keyseq and shell−command is either +whitespace or a colon optionally followed by whitespace. If +the separator is whitespace, shell−command must +be enclosed in double quotes and readline expands any +of its special backslash-escapes in +shell−command before saving it. If the +separator is a colon, any enclosing double quotes are +optional, and readline does not expand the command +string before saving it. Since the entire key binding +expression must be a single argument, it should be enclosed +in single quotes. When shell−command is +executed, the shell sets the +READLINE_LINE variable to the contents +of the readline line buffer and the +READLINE_POINT and +READLINE_MARK variables to the current +location of the insertion point and the saved insertion +point (the mark), respectively. The shell assigns any +numeric argument the user supplied to the +READLINE_ARGUMENT variable. If there +was no argument, that variable is not set. If the executed +command changes the value of any of +READLINE_LINE, +READLINE_POINT, or +READLINE_MARK, those +new values will be reflected in the editing state.

+ + + + + + + +
+ + +

−X

 + + +

List all key sequences bound to shell commands and the +associated commands in a format that can be reused as an +argument to a subsequent bind command.

+ +

The return +value is 0 unless an unrecognized option is supplied or an +error occurred.

+ +

break [n]

+ +

Exit from within a for, +while, until, or select loop. If +n is specified, break exits n enclosing +loops. n must be ≥ 1. If n is greater than +the number of enclosing loops, all enclosing loops are +exited. The return value is 0 unless n is not greater +than or equal to 1.

+ +

builtin +shell−builtin [arguments]

+ +

Execute the specified shell +builtin shell−builtin, passing it +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 cd builtin is commonly redefined +this way. The return status is false if +shell−builtin is not a shell builtin +command.

+ +

caller [expr]

+ +

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

+ +

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

+ +

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

+ +

cd [−L] +[−@] [dir]
+cd −P [−e] [−@] +[dir]

+ +

Change the current directory to +dir. if dir is not supplied, the value of the +HOME shell variable is used as +dir. If dir is the empty string, cd +treats it as an error. The variable +CDPATH exists, and dir does not +begin with a slash (/), cd uses it as a search path: +the shell searches each directory name in +CDPATH for dir. Alternative +directory names in CDPATH are +separated by a colon (:). A null directory name in +CDPATH is the same as the current +directory, i.e., “.”.

+ +

The +−P option causes cd to use the physical +directory structure by resolving symbolic links while +traversing dir and before processing instances of +.. in dir (see also the −P option +to the set builtin command).

+ +

The +−L option forces cd to follow symbolic +links by resolving the link after processing instances of +.. in dir. If .. appears in dir, +cd processes it by removing the immediately previous +pathname component from dir, back to a slash or the +beginning of dir, and verifying that the portion of +dir it has processed to that point is still a valid +directory name after removing the pathname component. If it +is not a valid directory name, cd returns a non-zero +status. If neither −L nor −P is +supplied, cd behaves as if −L had been +supplied.

+ +

If the +−e option is supplied with −P, and +cd cannot successfully determine the current working +directory after a successful directory change, it returns a +non-zero status.

+ +

On systems that +support it, the −@ option presents the extended +attributes associated with a file as a directory.

+ +

An argument of +− is converted to $OLDPWD +before attempting the directory change.

+ +

If cd +uses a non-empty directory name from +CDPATH, or if +− is the first argument, and the directory +change is successful, cd writes the absolute pathname +of the new working directory to the standard output.

+ +

If the +directory change is successful, cd sets the value of +the PWD environment variable to the new directory +name, and sets the OLDPWD environment variable to the +value of the current working directory before the +change.

+ +

The return +value is true if the directory was successfully changed; +false otherwise.

+ +

command +[−pVv] command [arg ...]

+ +

The command builtin runs +command with args suppressing the normal shell +function lookup for command. Only builtin commands or +commands found in the PATH named +command are executed. If the −p option +is supplied, the search for command is performed +using a default value for PATH that is +guaranteed to find all of the standard utilities.

+ +

If either the +−V or −v option is supplied, +command prints a description of command. The +−v option displays a single word indicating the +command or filename used to invoke command; the +−V option produces a more verbose +description.

+ +

If the +−V or −v option is supplied, the +exit status is zero if command was found, and +non-zero if not. If neither option is supplied and an error +occurred or command cannot be found, the exit status +is 127. Otherwise, the exit status of the command +builtin is the exit status of command.

+ +

compgen [−V +varname] [option] [word]

+ +

Generate possible completion +matches for word according to the options, +which may be any option accepted by the complete +builtin with the exceptions of −p, +−r, −D, −E, and +−I, and write the matches to the standard +output.

+ +

If the +−V option is supplied, compgen stores +the generated completions into the indexed array variable +varname instead of writing them to the standard +output.

+ +

When using the +−F or −C options, the various +shell variables set by the programmable completion +facilities, while available, will not have useful +values.

+ +

The matches +will be generated in the same way as if the programmable +completion code had generated them directly from a +completion specification with the same flags. If word +is specified, only those completions matching word +will be displayed or stored.

+ +

The return +value is true unless an invalid option is supplied, or no +matches were generated.

+ +

complete +[−abcdefgjksuv] [−o +comp-option] [−DEI] [−A +action]

+ +

[−G +globpat] [−W wordlist] +[−F function] [−C +command]
+[−X filterpat] [−P +prefix] [−S suffix] name +[name ...]

+ +

complete −pr +[−DEI] [name ...]

+ +

Specify how arguments to each +name should be completed.

+ +

If the +−p option is supplied, or if no options or +names are supplied, print existing completion +specifications in a way that allows them to be reused as +input. The −r option removes a completion +specification for each name, or, if no names +are supplied, all completion specifications.

+ +

The +−D option indicates that other supplied 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 −E option indicates that other supplied +options and actions should apply to “empty” +command completion; that is, completion attempted on a blank +line. The −I option indicates that other +supplied options and actions should apply to completion on +the initial non-assignment word on the line, or after a +command delimiter such as ; or |, which is +usually command name completion. If multiple options are +supplied, the −D option takes precedence over +−E, and both take precedence over +−I. If any of −D, −E, +or −I are supplied, any other name +arguments are ignored; these completions only apply to the +case specified by the option.

-
-If set, prompt strings undergo -parameter expansion, command substitution, arithmetic -expansion, and quote removal after being expanded as described in -PROMPTING - - - -above. -This option is enabled by default. -
restricted_shell - -
-The shell sets this option if it is started in restricted mode -(see -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. -
shift_verbose - -
-If set, the -shift - -builtin prints an error message when the shift count exceeds the -number of positional parameters. -
sourcepath - -
-If set, the -. (source) builtin uses the value of -PATH +

The process of +applying these completion specifications when attempting +word completion is described above under Programmable +Completion.

- -to find the directory containing the file supplied as an argument when -the -p option is not supplied. -This option is enabled by default. -
varredir_close +

Other options, +if specified, have the following meanings. The arguments to +the −G, −W, and −X +options (and, if necessary, the −P and +−S options) should be quoted to protect them +from expansion before the complete builtin is +invoked.
+−o comp-option

-
-If set, the shell automatically closes file descriptors assigned using the -{varname} redirection syntax (see -REDIRECTION - - - -above) -instead of leaving them open when the command completes. -
xpg_echo - -
-If set, the echo builtin expands backslash-escape sequences -by default. -If the posix shell option is also enabled, echo does not -interpret any options. -
- - -
suspend [-f]
-Suspend the execution of this shell until it receives a -SIGCONT - - -signal. -A login shell, or a shell without job control enabled, -cannot be suspended; the --f - -option will override this and force the suspension. -The return status is 0 unless the shell is a login shell -or job control is not enabled -and --f - -is not supplied. -
test expr
- -
[ expr ]
- -Return a status of 0 (true) or 1 (false) depending on -the evaluation of the conditional expression -expr. - -Each operator and operand must be a separate argument. -Expressions are composed of the primaries described - -above -under -CONDITIONAL EXPRESSIONS. - - -test does not accept any options, nor does it accept and ignore -an argument of -- as signifying the end of options. -
-Expressions may be combined using the following operators, listed -in decreasing order of precedence. -The evaluation depends on the number of arguments; see below. -test uses operator precedence when there are five or more arguments. -
- -
-
! expr - -
-True if -expr - -is false. -
( expr ) - -
-Returns the value of expr. -This may be used to override normal operator precedence. -
expr1 -a expr2
-True if both -expr1 - -and -expr2 - -are true. -
expr1 -o expr2
-True if either -expr1 - -or -expr2 - -is true. - -
-

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

- - -

-
0 arguments
-The expression is false. -
1 argument
-The expression is true if and only if the argument is not null. -
2 arguments
-If the first argument is !, the expression is true if and -only if the second argument is null. -If the first argument is one of the unary conditional operators listed - -above -under -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. -
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 -CONDITIONAL EXPRESSIONS, - - -the result of the expression is the result of the binary test using -the first and third arguments as operands. -The -a and -o operators are considered binary operators -when there are three arguments. -If the first argument is !, the value is the negation of -the two-argument test using the second and third arguments. -If the first argument is exactly ( and the third argument is -exactly ), the result is the one-argument test of the second -argument. -Otherwise, the expression is false. -
4 arguments
-The following conditions are applied in the order listed. -If the first argument is !, the result is the negation of -the three-argument expression composed of the remaining arguments. -If the first argument is exactly ( and the fourth argument is -exactly ), the result is the two-argument test of the second -and third arguments. -Otherwise, the expression is parsed and evaluated according to -precedence using the rules listed above. -
5 or more arguments
-The expression is parsed and evaluated according to precedence -using the rules listed above. - -
-

- -When the shell is in posix mode, or if the expression is part -of the [[ command, -the < and > operators sort using the -current locale. -If the shell is not in posix mode, the test and [ -commands sort lexicographically using ASCII ordering. -

- -The historical operator-precedence parsing with 4 or more arguments can -lead to ambiguities when it encounters strings that look like primaries. -The -POSIX -standard has deprecated the -a and -o -primaries and enclosing expressions within parentheses. -Scripts should no longer use them. -It's much more reliable to restrict test invocations to a single primary, -and to replace uses of -a and -o with the shell's -&& and || list operators. -

- -
times - -
-Print the accumulated user and system times for the shell and -for processes run from the shell. -The return status is 0. -
trap [-lpP] [[action] sigspec ...]
-The -action - -is a command that is read and executed when the shell receives -any of the signals -sigspec. - -If -action - -is absent (and there is a single sigspec) or --, - -each specified sigspec is -reset to the value it had when the shell was started. -If -action - -is the null string the signal specified by each -sigspec - -is ignored by the shell and by the commands it invokes. -
-If no arguments are supplied, -trap - -displays the actions associated with each trapped signal -as a set of trap commands -that can be reused as shell input to -restore the current signal dispositions. -If --p - -is given, -and -action - -is not present, -then trap displays the actions associated with each -sigspec - -or, if none are supplied, for all trapped signals, -as a set of trap commands -that can be reused as shell input to -restore the current signal dispositions. -The --P - -option behaves similarly, but displays only the actions -associated with each sigspec argument. --P - -requires at least one sigspec argument. -The -P or -p options may be used -in a subshell environment (e.g., command substitution) and, as -long as they are used before trap is used to change a signal's -handling, will display the state of its parent's traps. -
-The --l - -option prints a list of signal names and -their corresponding numbers. -Each -sigspec - -is either -a signal name defined in <signal.h>, or a signal number. -Signal names are case insensitive and the -SIG - - -prefix is optional. -If -l is supplied with no sigspec arguments, it prints a -list of valid signal names. -
-If a -sigspec - -is -EXIT - - -(0), -action - -is executed on exit from the shell. -If a -sigspec - -is -DEBUG, - - -action - -is executed before every simple command, for command, -case command, select command, (( arithmetic command, -[[ conditional command, -arithmetic for command, and before the first command executes -in a shell function (see -SHELL GRAMMAR - - - -above). -Refer to the description of the extdebug shell option -(see -shopt - - -above) -for details of its effect on the DEBUG trap. -If a -sigspec - -is -RETURN, - - -action - -is executed each time a shell function or a script executed with -the . or source builtins finishes executing. -
-If a -sigspec - -is -ERR, - - -action - -is executed whenever -a pipeline (which may consist of a single simple -command), a list, or a compound command returns a -non-zero exit status, -subject to the following conditions. -The -ERR - - -trap is not executed if the failed -command is part of the command list immediately following a -while +

The comp-option controls +several aspects of the compspec’s behavior beyond the +simple generation of completions. comp-option may be +one of:
+bashdefault

-or -until +

Perform the rest of the default +bash completions if the compspec generates no +matches.

-reserved word, -part of the test in an -if + + + + + + +
-statement, part of a command executed in a -&& -or -|| +

default

 -list except the command following the final && or ||, -any command in a pipeline but the last -(subject to the state of the pipefail shell option), -or if the command's return value is -being inverted using -!. -These are the same conditions obeyed by the errexit (-e) option. -
-When the shell is not interactive, -signals ignored upon entry to the shell cannot be trapped or reset. -Interactive shells permit trapping signals ignored on entry. -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 -sigspec +

Use readline’s default filename completion +if the compspec generates no matches.

-is invalid; otherwise -trap +

dirnames

-returns true. -
true
-Does nothing, returns a 0 status. -
type [-aftpP] name [name ...]
-Indicate how each -name +

Perform directory name +completion if the compspec generates no matches.

-would be interpreted if used as a command name. -
-If the --t +

filenames

-option is used, -type +

Tell readline that the +compspec generates filenames, so it can perform any +filename−specific processing (such as adding a slash +to directory names, quoting special characters, or +suppressing trailing spaces). This is intended to be used +with shell functions.

-prints a string which is one of -alias, +

fullquote

-keyword, +

Tell readline to quote +all the completed words even if they are not filenames.

-function, + + + + + + + + + + + + + + + + +
-builtin, -or -file +

noquote

 -if -name -is an alias, shell reserved word, function, builtin, or executable file, -respectively. -If the -name +

Tell readline not to quote the completed words if +they are filenames (quoting filenames is the default).

-is not found, type prints nothing and returns a non-zero exit status. -
-If the --p -option is used, -type +

nosort

 -either returns the pathname of the executable file -that would be found by searching -$PATH -for -name +

Tell readline not to sort the list of possible +completions alphabetically.

-or nothing if -would not return -file. +

nospace

 -The --P -option forces a -PATH +

Tell readline not to append a space (the default) +to words completed at the end of the line.

- -search for each name, even if +

plusdirs

-would not return -file. +

After generating any matches +defined by the compspec, attempt directory name completion +and add any matches to the results of the other actions.

-If name is present in the table of hashed commands, --p +

−A +action

-and --P +

The action may be one of +the following to generate a list of possible +completions:

-print the hashed value, which is not necessarily the file that appears -first in -PATH. + + + + + + + +
- -
-If the --a -option is used, -type +

alias

 -prints all of the places that contain a command named -name. -This includes aliases, reserved words, functions, and builtins, -but the path search options (-p and -P) -can be supplied to restrict the output to executable files. -type does not consult the table of hashed commands -when using --a +

Alias names. May also be specified as +−a.

 +
+ +

arrayvar

+ +

Array variable names.

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

binding

 + + +

Readline key binding names.

+ + +

builtin

 + + +

Names of shell builtin commands. May also be specified +as −b.

+ + +

command

 + + +

Command names. May also be specified as +−c.

+ +

directory

+ +

Directory names. May also be +specified as −d.

+ +

disabled

+ +

Names of disabled shell +builtins.

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

enabled

 + + +

Names of enabled shell builtins.

+ + +

export

 + + +

Names of exported shell variables. May also be specified +as −e.

+ + +

file

 + + +

File and directory names, similar to +readline’s filename completion. May also be +specified as −f.

+ +

function

+ +

Names of shell functions.

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

group

 + + +

Group names. May also be specified as +−g.

 +
+ +

helptopic

+ +

Help topics as accepted by the +help builtin.

+ +

hostname

+ +

Hostnames, as taken from the +file specified by the HOSTFILE shell +variable.

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

job

 + + +

Job names, if job control is active. May also be +specified as −j.

+ + +

keyword

 + + +

Shell reserved words. May also be specified as +−k.

+ + +

running

 + + +

Names of running jobs, if job control is active.

+ + +

service

 + + +

Service names. May also be specified as +−s.

+ + +

setopt

 + + +

Valid arguments for the −o option to the +set builtin.

+ + +

shopt

 + + +

Shell option names as accepted by the shopt +builtin.

+ + +

signal

 + + +

Signal names.

+ + +

stopped

 + + +

Names of stopped jobs, if job control is active.

+ + +

user

 + + +

User names. May also be specified as +−u.

+ +

variable

+ +

Names of all shell variables. +May also be specified as −v.

+ +

−C +command

+ +

command is executed in a +subshell environment, and its output is used as the possible +completions. Arguments are passed as with the +−F option.

+ +

−F +function

+ +

The shell function +function is executed in the current shell +environment. When the function is executed, the first +argument ($1) is the name of the command whose +arguments are being completed, the second argument +($2) is the word being completed, and the third +argument ($3) is the word preceding the word being +completed on the current command line. When function +finishes, programmable completion retrieves the possible +completions from the value of the +COMPREPLY array variable.

+ +

−G +globpat

+ +

Expand the pathname expansion +pattern globpat to generate the possible +completions.

+ +

−P +prefix

+ +

Add prefix to the +beginning of each possible completion after all other +options have been applied.

+ +

−S +suffix

+ +

Append suffix to each +possible completion after all other options have been +applied.

+ +

−W +wordlist

+ +

Split the wordlist using +the characters in the IFS special +variable as delimiters, and expand each resulting word. +Shell quoting is honored within wordlist, in order to +provide a mechanism for the words to contain shell +metacharacters or characters in the value of +IFS. The possible +completions are the members of the resultant list which +match a prefix of the word being completed.

+ +

−X +filterpat

+ +

filterpat 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 filterpat is +removed from the list. A leading ! in +filterpat negates the pattern; in this case, any +completion not matching filterpat is removed.

+ +

The return +value is true unless an invalid option is supplied, an +option other than −p, −r, +−D, −E, or −I is +supplied without a name argument, an attempt is made +to remove a completion specification for a name for +which no specification exists, or an error occurs adding a +completion specification.

+ +

compopt [−o +option] [−DEI] [+o option] +[name]

+ +

Modify completion options for +each name according to the options, or for the +currently-executing completion if no names are +supplied. If no options are supplied, display the +completion options for each name or the current +completion. The possible values of option are those +valid for the complete builtin described above.

+ +

The +−D option indicates that other supplied options +should apply to the “default” command +completion; the −E option indicates that other +supplied options should apply to “empty” command +completion; and the −I option indicates that +other supplied options should apply to completion on the +initial word on the line. These are determined in the same +way as the complete builtin.

+ +

If multiple +options are supplied, the −D option takes +precedence over −E, and both take precedence +over −I.

+ +

The return +value is true unless an invalid option is supplied, an +attempt is made to modify the options for a name for +which no completion specification exists, or an output error +occurs.

+ +

continue [n]

+ +

continue resumes the +next iteration of the enclosing for, while, +until, or select loop. If n is +specified, bash resumes the nth enclosing +loop. n must be ≥ 1. If n is greater than +the number of enclosing loops, the shell resumes the last +enclosing loop (the “top-level” loop). The +return value is 0 unless n is not greater than or +equal to 1.

+ +

declare +[−aAfFgiIlnrtux] [−p] +[name[=value] ...]
+typeset [−aAfFgiIlnrtux] [−p] +[name[=value] ...]

+ +

Declare variables and/or give +them attributes. If no names are given then display +the values of variables or functions. The −p +option will display the attributes and values of each +name. When −p is used with name +arguments, additional options, other than −f +and −F, are ignored.

+ +

When +−p is supplied without name arguments, +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 +−p, declare will display the attributes +and values of all shell variables. The −f +option restricts the display to shell functions.

+ +

The +−F option inhibits the display of function +definitions; only the function name and attributes are +printed. If the extdebug shell option is enabled +using shopt, the source file name and line number +where each name is defined are displayed as well. The +−F option implies −f.

+ +

The +−g option forces variables to be created or +modified at the global scope, even when declare is +executed in a shell function. It is ignored when +declare is not executed in a shell function.

+ +

The +−I option causes local variables to inherit the +attributes (except the nameref attribute) and value +of any existing variable with the same name at a +surrounding scope. If there is no existing variable, the +local variable is initially unset.

+ +

The following +options can be used to restrict output to variables with the +specified attribute or to give variables attributes:

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

−a

 + + +

Each name is an indexed array variable (see +Arrays above).

+ + +

−A

 + + +

Each name is an associative array variable (see +Arrays above).

+ + +

−f

 + + +

Each name refers to a shell function.

+ + +

−i

 + + +

The variable is treated as an integer; arithmetic +evaluation (see ARITHMETIC EVALUATION +above) is performed when the variable is assigned a +value.

+ + +

−l

 + + +

When the variable is assigned a value, all upper-case +characters are converted to lower-case. The upper-case +attribute is disabled.

+ + +

−n

 + + +

Give each name the nameref attribute, +making it a name reference to another variable. That other +variable is defined by the value of name. All +references, assignments, and attribute modifications to +name, except those using or changing the +−n attribute itself, are performed on the +variable referenced by name’s value. The +nameref attribute cannot be applied to array variables.

+ + +

−r

 + + +

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

+ + +

−t

 + + +

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

+ + +

−u

 + + +

When the variable is assigned a value, all lower-case +characters are converted to upper-case. The lower-case +attribute is disabled.

+ + +

−x

 + + +

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

+ +

Using +“+” instead of “−” turns off +the specified attribute instead, with the exceptions that ++a and +A may not be used to destroy array +variables and +r will not remove the readonly +attribute.

+ +

When used in a +function, declare and typeset make each +name local, as with the local command, unless +the −g option is supplied. If a variable name +is followed by =value, the value of the variable is +set to value. When using −a or +−A and the compound assignment syntax to create +array variables, additional attributes do not take effect +until subsequent assignments.

+ +

The return +value is 0 unless an invalid option is encountered, an +attempt is made to define a function using “−f +foo=bar”, an attempt is made to assign a value to a +readonly variable, an attempt is made to assign a value to +an array variable without using the compound assignment +syntax (see Arrays above), one of the names is +not a valid shell variable name, an attempt is made to turn +off readonly status for a readonly variable, an attempt is +made to turn off array status for an array variable, or an +attempt is made to display a non-existent function with +−f.

+ +

dirs [−clpv] +[+n] [−n]

+ +

Without options, display 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 +pushd command; the popd command removes +entries from the list. The current directory is always the +first directory in the stack.

+ +

Options, if +supplied, have the following meanings:

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

−c

 + + +

Clears the directory stack by deleting all of the +entries.

+ + +

−l

 + + +

Produces a listing using full pathnames; the default +listing format uses a tilde to denote the home +directory.

+ + +

−p

 + + +

Print the directory stack with one entry per line.

+ + +

−v

 + + +

Print the directory stack with one entry per line, +prefixing each entry with its index in the stack.

+ + +

+n

 + + +

Displays the nth entry counting from the left of +the list shown by dirs when invoked without options, +starting with zero.

+ + +

−n

 + + +

Displays the nth entry counting from the right of +the list shown by dirs when invoked without options, +starting with zero.

+ +

The return +value is 0 unless an invalid option is supplied or n +indexes beyond the end of the directory stack.

+ +

disown [−ar] +[−h] [id ...]

+ +

Without options, remove each +id from the table of active jobs. Each id may +be a job specification jobspec or a process ID +pid; if id is a pid, disown uses +the job containing pid as jobspec.

+ +

If the +−h option is supplied, disown does not +remove the jobs corresponding to each id from the +jobs table, but rather marks them so the shell does not send +SIGHUP to the job if the shell +receives a SIGHUP.

+ +

If no id +is supplied, the −a option means to remove or +mark all jobs; the −r option without an +id argument removes or marks running jobs. If no +id is supplied, and neither the −a nor +the −r option is supplied, disown +removes or marks the current job.

+ +

The return +value is 0 unless an id does not specify a valid +job.

+ +

echo [−neE] +[arg ...]

+ +

Output the args, +separated by spaces, followed by a newline. The return +status is 0 unless a write error occurs. If −n +is specified, the trailing newline is not printed.

+ +

If the +−e option is given, echo interprets the +following backslash-escaped characters. The −E +option disables interpretation of these escape characters, +even on systems where they are interpreted by default. The +xpg_echo shell option determines whether or not +echo interprets any options and expands these escape +characters. echo does not interpret +−− to mean the end of options.

+ +

echo +interprets the following escape sequences:

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

\a

 + + +

alert (bell)

+ + +

\b

 + + +

backspace

+ + +

\c

 + + +

suppress further output

+ + +

\e

 +
+ + +

\E

 + + +

an escape character

+ + +

\f

 + + +

form feed

+ + +

\n

 + + +

new line

+ + +

\r

 + + +

carriage return

+ + +

\t

 + + +

horizontal tab

+ + +

\v

 + + +

vertical tab

+ + +

\\

 + + +

backslash

+ + +

\0nnn

 + + +

The eight-bit character whose value is the octal value +nnn (zero to three octal digits).

+ + +

\xHH

 + + +

The eight-bit character whose value is the hexadecimal +value HH (one or two hex digits).

+ + +

\uHHHH

 + + +

The Unicode (ISO/IEC 10646) character whose value is the +hexadecimal value HHHH (one to four hex digits).

+ +

\UHHHHHHHH

+ +

The Unicode (ISO/IEC 10646) +character whose value is the hexadecimal value +HHHHHHHH (one to eight hex digits).

+ +

echo +writes any unrecognized backslash-escaped characters +unchanged.

+ +

enable [−a] +[−dnps] [−f filename] +[name ...]

+ +

Enable and disable builtin +shell commands. Disabling a builtin allows an executable +file 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 files.

+ +

If +−n is supplied, each name is disabled; +otherwise, names are enabled. For example, to use the +test binary found using PATH +instead of the shell builtin version, run “enable +−n test”.

+ +

If no +name arguments are supplied, or if the +−p option is supplied, print a list of shell +builtins. With no other option arguments, the list consists +of all enabled shell builtins. If −n is +supplied, print only disabled builtins. If −a +is supplied, the list printed includes all builtins, with an +indication of whether or not each is enabled. The +−s option means to restrict the output to the +POSIX special builtins.

+ +

The +−f option means to load the new builtin command +name from shared object filename, on systems +that support dynamic loading. If filename does not +contain a slash, Bash will use the value of the +BASH_LOADABLES_PATH variable as a colon-separated +list of directories in which to search for filename. +The default for BASH_LOADABLES_PATH is +system-dependent, and may include “.” to force a +search of the current directory. The −d option +will delete a builtin previously loaded with +−f. If −s is used with +−f, the new builtin becomes a +POSIX special builtin.

+ +

If no options +are supplied and a name is not a shell builtin, +enable will attempt to load name from a shared +object named name, as if the command were +“enable −f name name”.

+ +

The return +value is 0 unless a name is not a shell builtin or +there is an error loading a new builtin from a shared +object.

+ +

eval [arg ...]

+ +

Concatenate the args +together into a single command, separating them with spaces. +Bash then reads and execute this command, and returns +its exit status as the return status of eval. If +there are no args, or only null arguments, +eval returns 0.

+ +

exec [−cl] +[−a name] [command +[arguments]]

+ +

If command is specified, +it replaces the shell without creating a new process. +command cannot be a shell builtin or function. The +arguments become the arguments to command. If +the −l option is supplied, the shell places a +dash at the beginning of the zeroth argument passed to +command. This is what login(1) does. The +−c option causes command to be executed +with an empty environment. If −a is supplied, +the shell passes name as the zeroth argument to the +executed command.

+ +

If +command cannot be executed for some reason, a +non-interactive shell exits, unless the execfail +shell option is enabled. In that case, it returns a non-zero +status. An interactive shell returns a non-zero status if +the file cannot be executed. A subshell exits +unconditionally if exec fails.

+ +

If +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.

+ +

exit [n]

+ +

Cause the shell to exit with a +status of n. If n is omitted, the exit status +is that of the last command executed. Any trap on +EXIT is executed before the shell +terminates.

+ +

export [−fn] +[name[=value]] ...
+export −p [−f]

+ +

The supplied names are +marked for automatic export to the environment of +subsequently executed commands. If the −f +option is given, the names refer to functions.

+ +

The +−n option unexports, or removes the export +attribute, from each name. If no names are +given, or if only the −p option is supplied, +export displays a list of names of all exported +variables on the standard output. Using −p and +−f together displays exported functions. The +−p option displays output in a form that may be +reused as input.

+ +

export +allows the value of a variable to be set when it is exported +or unexported by following the variable name with +=value. This sets the value of the variable to +value while modifying the export attribute. +export returns an exit status of 0 unless an invalid +option is encountered, one of the names is not a +valid shell variable name, or −f is supplied +with a name that is not a function.

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

false

 + + +

Does nothing; returns a non-zero status.

 +
+ +

fc [−e +ename] [−lnr] [first] +[last]
+fc −s [pat=rep] [cmd]

+ +

The first form selects a range +of commands from first to last from the +history list and displays or edits and re-executes them. +First and 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).

+ +

When listing, a +first or last of 0 is equivalent to −1 +and −0 is equivalent to the current command (usually +the fc command); otherwise 0 is equivalent to +−1 and −0 is invalid. If last is not +specified, it is set to the current command for listing (so +that “fc −l −10” prints the last 10 +commands) and to first otherwise. If first is +not specified, it is set to the previous command for editing +and −16 for listing.

+ +

If the +−l option is supplied, the commands are listed +on the standard output. The −n option +suppresses the command numbers when listing. The +−r option reverses the order of the +commands.

+ +

Otherwise, +fc invokes the editor named by ename on a file +containing those commands. If ename is not supplied, +fc uses the value of the FCEDIT +variable, and the value of EDITOR if +FCEDIT is not set. If neither variable +is set, fc uses vi. When editing is complete, +fc reads the file containing the edited commands and +echoes and executes them.

+ +

In the second +form, fc re-executes command after replacing +each instance of pat with rep. Command +is interpreted the same as first above.

+ +

A useful alias +to use with fc is “r="fc +−s"”, so that typing “r cc” +runs the last command beginning with “cc” and +typing “r” re-executes the last command.

+ +

If the first +form is used, the return value is zero unless an invalid +option is encountered or first or last specify +history lines out of range. When editing and re-executing a +file of commands, the return value is the value of the last +command executed or failure if an error occurs with the +temporary file. If the second form is used, the return +status is that of the re-executed command, unless cmd +does not specify a valid history entry, in which case +fc returns a non-zero status.

+ +

fg [jobspec]

+ +

Resume jobspec in the +foreground, and make it the current job. If jobspec +is not present, fg uses the shell’s notion of +the current job. 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 jobspec does not specify a valid job or +jobspec specifies a job that was started without job +control.

+ +

getopts optstring +name [arg ...]

+ +

getopts is used by shell +scripts and functions to parse positional parameters and +obtain options and their arguments. 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, getopts places the next option in the shell +variable name, initializing name if it does +not exist, and the index of the next argument to be +processed into the variable +OPTIND. OPTIND +is initialized to 1 each time the shell or a shell script is +invoked. When an option requires an argument, getopts +places that argument into the variable +OPTARG.

+ +

The shell does +not reset OPTIND automatically; it +must be manually reset between multiple calls to +getopts within the same shell invocation to use a new +set of parameters.

+ +

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

+ +

getopts +normally parses the positional parameters, but if more +arguments are supplied as arg values, getopts +parses those instead.

+ +

getopts +can report errors in two ways. If the first character of +optstring is a colon, getopts uses +silent error reporting. In normal operation, +getopts prints diagnostic messages when it encounters +invalid options or missing option arguments. If the variable +OPTERR is set to 0, getopts +does not display any error messages, even if the first +character of optstring is not a colon.

+ +

If +getopts detects an invalid option, it places ? into +name and, if not silent, prints an error message and +unsets OPTARG. If +getopts is silent, it assigns the option character +found to OPTARG and does not print a +diagnostic message.

+ +

If a required +argument is not found, and getopts is not silent, it +sets the value of name to a question mark (?), +unsets OPTARG, and +prints a diagnostic message. If getopts is silent, it +sets the value of name to a colon (:) and sets +OPTARG to the option character +found.

+ +

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.

+ +

hash [−lr] +[−p filename] [−dt] +[name]

+ +

Each time hash is +invoked, it remembers the full pathname of the command +name as determined by searching the directories in +$PATH. Any previously-remembered pathname associated +with name is discarded. If the −p option +is supplied, hash uses filename as the full +pathname of the command.

+ +

The +−r option causes the shell to forget all +remembered locations. Assigning to the PATH variable +also clears all hashed filenames. The −d option +causes the shell to forget the remembered location of each +name.

+ +

If the +−t option is supplied, hash prints the +full pathname corresponding to each name. If multiple +name arguments are supplied with −t, +hash prints the name before the corresponding +hashed full pathname. The −l option displays +output in a format that may be reused as input.

+ +

If no arguments +are given, or if only −l is supplied, +hash prints information about remembered commands. +The −t, −d, and −p +options (the options that act on the name arguments) +are mutually exclusive. Only one will be active. If more +than one is supplied, −t has higher priority +than −p, and both have higher priority than +−d.

+ +

The return +status is zero unless a name is not found or an +invalid option is supplied.

+ +

help [−dms] +[pattern]

+ +

Display helpful information +about builtin commands. If pattern is specified, +help gives detailed help on all commands matching +pattern as described below; otherwise it displays a +list of all the builtins and shell compound commands.

+ +

Options, if +supplied, have the follow meanings:

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

−d

 + + +

Display a short description of each pattern

+ + +

−m

 + + +

Display the description of each pattern in a +manpage-like format

+ + +

−s

 + + +

Display only a short usage synopsis for each +pattern

+ +

If +pattern contains pattern matching characters (see +Pattern Matching above) it’s +treated as a shell pattern and help prints the +description of each help topic matching pattern.

+ +

If not, and +pattern exactly matches the name of a help topic, +help prints the description associated with that +topic. Otherwise, help performs prefix matching and +prints the descriptions of all matching help topics.

+ +

The return +status is 0 unless no command matches pattern.

+ +

history [n] +
+history −c
+history −d offset
+history −d start-end
+history −anrw [filename]
+history −p arg [arg ...]
+history −s arg [arg ...]

+ +

With no options, display the +command history list with numbers. Entries prefixed with a +* have been modified. An argument of n lists +only the last n entries. If the shell variable +HISTTIMEFORMAT is set and not null, it +is used as a format string for strftime(3) to display +the time stamp associated with each displayed history entry. +If history uses +HISTTIMEFORMAT, it does +not print an intervening space between the formatted time +stamp and the history entry.

+ +

If +filename is supplied, history uses it as the +name of the history file; if not, it uses the value of +HISTFILE. If +filename is not supplied and +HISTFILE is unset or null, the +−a, −n, −r, and −w +options have no effect.

+ +

Options, if +supplied, have the following meanings:

+ + + + + + + +
+ + +

−c

 + + +

Clear the history list by deleting all the entries. This +can be used with the other options to replace the history +list.

+ +

−d +offset

+ +

Delete the history entry at +position offset. If offset is negative, it is +interpreted as relative to one greater than the last history +position, so negative indices count back from the end of the +history, and an index of −1 refers to the current +history −d command.

+ +

−d +start−end

+ +

Delete the range of history +entries between positions start and end, +inclusive. Positive and negative values for start and +end are interpreted as described above.

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

−a

 + + +

Append the “new” history lines to the +history file. These are history lines entered since the +beginning of the current bash session, but not +already appended to the history file.

+ + +

−n

 + + +

Read the history lines not already read from the history +file and add them to the current history list. These are +lines appended to the history file since the beginning of +the current bash session.

+ + +

−r

 + + +

Read the history file and append its contents to the +current history list.

+ + +

−w

 + + +

Write the current history list to the history file, +overwriting the history file.

+ + +

−p

 + + +

Perform history substitution on the following +args and display the result on the standard output, +without storing the results in the history list. Each +arg must be quoted to disable normal history +expansion.

+ + +

−s

 + + +

Store the args in the history list as a single +entry. The last command in the history list is removed +before adding the args.

+ +

If the +HISTTIMEFORMAT variable is set, +history writes the time stamp information associated +with each history entry to the history file, marked with the +history comment character as described above. When the +history file is read, lines beginning with the history +comment character followed immediately by a digit are +interpreted as timestamps for the following history +entry.

+ +

The return +value is 0 unless an invalid option is encountered, an error +occurs while reading or writing the history file, an invalid +offset or range is supplied as an argument to +−d, or the history expansion supplied as an +argument to −p fails.

+ +

jobs +[−lnprs] [ jobspec ... ]
+jobs −x command [ args ... ]

+ +

The first form lists the active +jobs. The options have the following meanings:

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

−l

 + + +

List process IDs in addition to the normal +information.

+ + +

−n

 + + +

Display information only about jobs that have changed +status since the user was last notified of their status.

+ + +

−p

 + + +

List only the process ID of the job’s process +group leader.

+ + +

−r

 + + +

Display only running jobs.

+ + +

−s

 + + +

Display only stopped jobs.

+ +

If +jobspec is supplied, jobs restricts output to +information about that job. The return status is 0 unless an +invalid option is encountered or an invalid jobspec +is supplied.

+ +

If the +−x option is supplied, jobs replaces any +jobspec found in command or args with +the corresponding process group ID, and executes +command, passing it args, returning its exit +status.

+ +

kill [−s +sigspec | −n signum | +−sigspec] id [ ... ]
+kill −l|−L [sigspec | +exit_status]

+ +

Send the signal specified by +sigspec or signum to the processes named by +each id. Each id may be a job specification +jobspec or a process ID pid. sigspec is +either a case-insensitive signal name such as +SIGKILL (with or without the +SIG prefix) or a signal number; +signum is a signal number. If sigspec is not +supplied, then kill sends +SIGTERM.

+ +

The +−l option lists the signal names. If any +arguments are supplied when −l is given, +kill lists the names of the signals corresponding to +the arguments, and the return status is 0. The +exit_status argument to −l is a number +specifying either a signal number or the exit status of a +process terminated by a signal; if it is supplied, +kill prints the name of the signal that caused the +process to terminate. kill assumes that process exit +statuses are greater than 128; anything less than that is a +signal number. The −L option is equivalent to +−l.

+ +

kill +returns true if at least one signal was successfully sent, +or false if an error occurs or an invalid option is +encountered.

+ +

let arg +[arg ...]

+ +

Each arg is evaluated as +an arithmetic expression (see ARITHMETIC +EVALUATION above). If the last arg +evaluates to 0, let returns 1; otherwise let +returns 0.

+ +

local [option] +[name[=value] ... | − ]

+ +

For each argument, create a +local variable named name and assign it value. +The option can be any of the options accepted by +declare. When local is used within a function, +it causes the variable name to have a visible scope +restricted to that function and its children. It is an error +to use local when not within a function.

+ +

If name +is −, it makes the set of shell options local to the +function in which local is invoked: any shell options +changed using the set builtin inside the function +after the call to local are restored to their +original values when the function returns. The restore is +performed as if a series of set commands were +executed to restore the values that were in place before the +function.

+ +

With no +operands, local writes a list of local variables to +the standard output.

+ +

The return +status is 0 unless local is used outside a function, +an invalid name is supplied, or name is a +readonly variable.

+ +

logout +[n]

+ +

Exit a login shell, returning a +status of n to the shell’s parent.

+ +

mapfile [−d +delim] [−n count] +[−O origin] [−s +count] [−t] [−u fd] +[−C
+callback] [−c quantum] +[array]
+readarray [−d delim] +[−n count] [−O +origin] [−s count] +[−t] [−u fd] +[−C
+callback] [−c quantum] +[array]

+ +

Read lines from the standard +input, or from file descriptor fd if the +−u option is supplied, into the indexed array +variable array. The variable +MAPFILE is the default array. +Options, if supplied, have the following meanings:

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

−d

 + + +

Use the first character of delim to terminate +each input line, rather than newline. If delim is the +empty string, mapfile will terminate a line when it +reads a NUL character.

+ + +

−n

 + + +

Copy at most count lines. If count is 0, +copy all lines.

+ + +

−O

 + + +

Begin assigning to array at index origin. +The default index is 0.

+ + +

−s

 + + +

Discard the first count lines read.

+ + +

−t

 + + +

Remove a trailing delim (default newline) from +each line read.

+ + +

−u

 + + +

Read lines from file descriptor fd instead of the +standard input.

+ + +

−C

 + + +

Evaluate callback each time quantum lines +are read. The −c option specifies +quantum.

+ + +

−c

 + + +

Specify the number of lines read between each call to +callback.

+ +

If +−C is specified without −c, the +default quantum is 5000. When 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. callback is evaluated after the +line is read but before the array element is assigned.

+ +

If not supplied +with an explicit origin, mapfile will clear +array before assigning to it.

+ +

mapfile +returns zero unless an invalid option or option argument is +supplied, array is invalid or unassignable, or if +array is not an indexed array.

+ +

popd [−n] +[+n] [−n]

+ +

Remove entries from the +directory stack. The elements are numbered from 0 starting +at the first directory listed by dirs, so popd +is equivalent to “popd +0.” With no arguments, +popd removes the top directory from the stack, and +changes to the new top directory. Arguments, if supplied, +have the following meanings:

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

−n

 + + +

Suppress the normal change of directory when removing +directories from the stack, only manipulate the stack.

+ + +

+n

 + + +

Remove the nth entry counting from the left of +the list shown by dirs, starting with zero, from the +stack. For example: “popd +0” removes the first +directory, “popd +1” the second.

+ + +

−n

 + + +

Remove the nth entry counting from the right of +the list shown by dirs, starting with zero. For +example: “popd −0” removes the last +directory, “popd −1” the next to last.

+ +

If the top +element of the directory stack is modified, and the +−n option was not supplied, popd uses +the cd builtin to change to the directory at the top +of the stack. If the cd fails, popd returns a +non-zero value.

+ +

Otherwise, +popd returns false if an invalid option is supplied, +the directory stack is empty, or n specifies a +non-existent directory stack entry.

+ +

If the +popd command is successful, bash runs +dirs to show the final contents of the directory +stack, and the return status is 0.

+ +

printf [−v +var] format [arguments]

+ +

Write the formatted +arguments to the standard output under the control of +the format. The −v option assigns the +output to the variable var rather than printing it to +the standard output.

+ +

The +format is a character string which contains three +types of objects: plain characters, which are simply copied +to standard output, character escape sequences, which are +converted and copied to the standard output, and format +specifications, each of which causes printing of the next +successive argument. In addition to the standard +printf(3) format characters +cCsSndiouxXeEfFgGaA, printf interprets the +following additional format specifiers:

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

%b

 + + +

causes printf to expand backslash escape +sequences in the corresponding argument in the same +way as echo −e.

+ + +

%q

 + + +

causes printf to output the corresponding +argument in a format that can be reused as shell +input. %q and %Q use the $'' quoting +style if any characters in the argument string require it, +and backslash quoting otherwise. If the format string uses +the printf alternate form, these two formats quote +the argument string using single quotes.

+ + +

%Q

 + + +

like %q, but applies any supplied precision to +the argument before quoting it.

+ + +

%(datefmt)T

+ +

causes printf to output +the date-time string resulting from using datefmt as +a format string for strftime(3). The corresponding +argument is an integer representing the number of +seconds since the epoch. This format specifier recognizes +two special argument values: −1 represents the current +time, and −2 represents the time the shell was +invoked. If no argument is specified, conversion behaves as +if −1 had been supplied. This is an exception to the +usual printf behavior.

+ +

The %b, %q, and +%T format specifiers all use the field width and precision +arguments from the format specification and write that many +bytes from (or use that wide a field for) the expanded +argument, which usually contains more characters than the +original.

+ +

The %n format +specifier accepts a corresponding argument that is treated +as a shell variable name.

+ +

The %s and %c +format specifiers accept an l (long) modifier, which forces +them to convert the argument string to a wide-character +string and apply any supplied field width and precision in +terms of characters, not bytes. The %S and %C format +specifiers are equivalent to %ls and %lc, respectively.

+ +

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 numeric value of the following character, using the +current locale.

+ +

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

+ +

pushd [−n] +[+n] [−n]
+pushd [−n] [dir]

+ +

Add a directory to the top of +the directory stack, or rotate the stack, making the new top +of the stack the current working directory. With no +arguments, pushd exchanges the top two elements of +the directory stack. Arguments, if supplied, have the +following meanings:

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

−n

 + + +

Suppress the normal change of directory when rotating or +adding directories to the stack, only manipulate the +stack.

+ + +

+n

 + + +

Rotate the stack so that the nth directory +(counting from the left of the list shown by dirs, +starting with zero) is at the top.

+ + +

−n

 + + +

Rotates the stack so that the nth directory +(counting from the right of the list shown by dirs, +starting with zero) is at the top.

+ + +

dir

 + + +

Adds dir to the directory stack at the top.

+ +

After the stack +has been modified, if the −n option was not +supplied, pushd uses the cd builtin to change +to the directory at the top of the stack. If the cd +fails, pushd returns a non-zero value.

+ +

Otherwise, if +no arguments are supplied, pushd returns zero unless +the directory stack is empty. When rotating the directory +stack, pushd returns zero unless the directory stack +is empty or n specifies a non-existent directory +stack element.

+ +

If the +pushd command is successful, bash runs +dirs to show the final contents of the directory +stack.

+ +

pwd +[−LP]

+ +

Print the absolute pathname of +the current working directory. The pathname printed contains +no symbolic links if the −P option is supplied +or the −o physical option to the set +builtin command is enabled. If the −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.

+ +

read [−Eers] +[−a aname] [−d +delim] [−i text] [−n +nchars] [−N nchars]
+[−p prompt] [−t +timeout] [−u fd] [name +...]

+ +

Read one line from the standard +input, or from the file descriptor fd supplied as an +argument to the −u option, split it into words +as described above under Word Splitting, and assign +the first word to the first name, the second word to +the second name, and so on. If there are more words +than names, the remaining words and their intervening +delimiters are assigned to the last name. If there +are fewer words read from the input stream than names, the +remaining names are assigned empty values. The characters in +the value of the IFS variable are used +to split the line into words using the same rules the shell +uses for expansion (described above under Word +Splitting). The backslash character (\) removes +any special meaning for the next character read and is used +for line continuation.

+ +

Options, if +supplied, have the following meanings:
+−a aname

+ +

The words are assigned to +sequential indices of the array variable aname, +starting at 0. aname is unset before any new values +are assigned. Other name arguments are ignored.

+ +

−d +delim

+ +

The first character of +delim terminates the input line, rather than newline. +If delim is the empty string, read will +terminate a line when it reads a NUL character.

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

−e

 + + +

If the standard input is coming from a terminal, +read uses readline (see +READLINE above) to obtain the line. +Readline uses the current (or default, if line +editing was not previously active) editing settings, but +uses readline’s default filename +completion.

+ + +

−E

 + + +

If the standard input is coming from a terminal, +read uses readline (see +READLINE above) to obtain the line. +Readline uses the current (or default, if line +editing was not previously active) editing settings, but +uses bash’s default completion, including programmable +completion.

+ +

−i text

+ +

If readline is being +used to read the line, read places text into +the editing buffer before editing begins.

+ +

−n +nchars

+ +

read returns after +reading nchars characters rather than waiting for a +complete line of input, unless it encounters EOF or +read times out, but honors a delimiter if it reads +fewer than nchars characters before the +delimiter.

+ +

−N +nchars

+ +

read returns after +reading exactly nchars characters rather than waiting +for a complete line of input, unless it encounters EOF or +read times out. Any delimiter characters in the input +are not treated specially and do not cause read to +return until it has read nchars characters. The +result is not split on the characters in IFS; the +intent is that the variable is assigned exactly the +characters read (with the exception of backslash; see the +−r option below).

+ +

−p +prompt

+ +

Display prompt on +standard error, without a trailing newline, before +attempting to read any input, but only if input is coming +from a terminal.

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

−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 then be used as +a line continuation.

+ + +

−s

 + + +

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

+ +

−t +timeout

+ +

Cause read to time out +and return failure if it does not read a complete line of +input (or a specified number of characters) within +timeout seconds. timeout may be a decimal +number with a fractional portion following the decimal +point. This option is only effective if read is +reading input from a terminal, pipe, or other special file; +it has no effect when reading from regular files. If +read times out, it saves any partial input read into +the specified variable name, and the exit status is +greater than 128. If timeout is 0, read +returns immediately, without trying to read any data. In +this case, the exit status is 0 if input is available on the +specified file descriptor, or the read will return EOF, +non-zero otherwise.

+ + + + + + + +
+ + +

−u fd

 + + +

Read input from file descriptor fd instead of the +standard input.

+ +

Other than the +case where delim is the empty string, read +ignores any NUL characters in the input.

+ +

If no +names are supplied, read assigns the line +read, without the ending delimiter but otherwise unmodified, +to the variable +REPLY.

+ +

The exit status +is zero, unless end-of-file is encountered, read +times out (in which case the status is greater than 128), a +variable assignment error (such as assigning to a readonly +variable) occurs, or an invalid file descriptor is supplied +as the argument to −u.

+ +

readonly +[−aAf] [−p] +[name[=word] ...]

+ +

The given names are +marked readonly; the values of these names may not be +changed by subsequent assignment or unset. If the +−f option is supplied, each name refers +to a shell function. The −a option restricts +the variables to indexed arrays; the −A option +restricts the variables to associative arrays. If both +options are supplied, −A takes precedence. If +no name arguments are supplied, or if the +−p option is supplied, print a list of all +readonly names. The other options may be used to restrict +the output to a subset of the set of readonly names. The +−p option displays output in a format that may +be reused as input.

+ + +

readonly +allows the value of a variable to be set at the same time +the readonly attribute is changed by following the variable +name with =value. This sets the value of the variable +is to value while modifying the readonly +attribute.

+ +

The return +status is 0 unless an invalid option is encountered, one of +the names is not a valid shell variable name, or +−f is supplied with a name that is not a +function.

+ +

return [n]

+ +

Stop executing a shell function +or sourced file and return the value specified by n +to its caller. If n is omitted, the return status is +that of the last command executed. If return is +executed by a trap handler, the last command used to +determine the status is the last command executed before the +trap handler. If return is executed during a +DEBUG trap, the last command used to determine the +status is the last command executed by the trap handler +before return was invoked.

+ +

When +return is used to terminate execution of a script +being executed by the . (source) command, it +causes the shell to stop executing that script and return +either n or the exit status of the last command +executed within the script as the exit status of the script. +If n is supplied, the return value is its least +significant 8 bits.

+ +

Any command +associated with the RETURN trap is executed before +execution resumes after the function or script.

+ +

The return +status is non-zero if return is supplied a +non-numeric argument, or is used outside a function and not +during execution of a script by . or +source.

+ +

set +[−abefhkmnptuvxBCEHPT] [−o +option−name] [−−] +[−] [arg ...]
+set [+abefhkmnptuvxBCEHPT] [+o +option−name] [−−] +[−] [arg ...]

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

set −o

 +
+ + +

set +o

 + + +

Without options, display the name and value of each +shell variable in a format that can be reused as input for +setting or resetting the currently-set variables. Read-only +variables cannot be reset. In posix mode, only shell +variables are listed. 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 $1, +$2, ..., $n. Options, if specified, +have the following meanings:

+ +

−a

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

Each variable or function that +is created or modified is given the export attribute and +marked for export to the environment of subsequent +commands.

+ + +

−b

 + + +

Report the status of terminated background jobs +immediately, rather than before the next primary prompt or +after a foreground command terminates. This is effective +only when job control is enabled.

+ + +

−e

 + + +

Exit immediately if a pipeline (which may consist +of a single simple command), a list, or a +compound command (see 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 while or +until reserved word, part of the test following the +if or elif reserved words, part of any command +executed in a && or || list except the +command following the final && or ||, +any command in a pipeline but the last (subject to the state +of the pipefail shell option), or if the +command’s return value is being inverted with +!. If a compound command other than a subshell +returns a non-zero status because a command failed while +−e was being ignored, the shell does not exit. +A trap on ERR, if set, is executed before the shell +exits. This option applies to the shell environment and each +subshell environment separately (see COMMAND +EXECUTION ENVIRONMENT above), and may cause +subshells to exit before executing all the commands in the +subshell.

+ +

If a compound +command or shell function executes in a context where +−e is being ignored, none of the commands +executed within the compound command or function body will +be affected by the −e setting, even if +−e is set and a command returns a failure +status. If a compound command or shell function sets +−e while executing in a context where +−e is ignored, that setting will not have any +effect until the compound command or the command containing +the function call completes.

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

−f

 + + +

Disable pathname expansion.

+ + +

−h

 + + +

Remember the location of commands as they are looked up +for execution. This is enabled by default.

+ + +

−k

 + + +

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

+ + +

−m

 + + +

Monitor mode. Job control is enabled. This option is on +by default for interactive shells on systems that support it +(see 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.

+ + +

−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.

+ +

−o +option−name

+ +

The option−name +can be one of the following:
+allexport

+ +

Same as −a.

+ +

braceexpand

+ +

Same as −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 −−noediting +option. This also affects the editing interface used for +read −e.

+ + +

errexit

 + + +

Same as −e.

+ +

errtrace

+ +

Same as −E.

+ +

functrace

+ +

Same as −T.

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

hashall

 + + +

Same as −h.

 +
+ +

histexpand

+ +

Same as −H.

+ + + + + + + +
+ + +

history

 + + +

Enable command history, as described above under +HISTORY. This option is +on by default in interactive shells.

+ +

ignoreeof

+ +

The effect is as if the shell +command “IGNOREEOF=10” had been executed (see +Shell Variables above).

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

keyword

 + + +

Same as −k.

 +
+ + +

monitor

 + + +

Same as −m.

 +
+ +

noclobber

+ +

Same as −C.

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

noexec

 + + +

Same as −n.

 +
+ + +

noglob

 + + +

Same as −f.

 +
+ + +

nolog

 + + +

Currently ignored.

 +
+ + +

notify

 + + +

Same as −b.

 +
+ + +

nounset

 + + +

Same as −u.

 +
+ + +

onecmd

 + + +

Same as −t.

 +
+ +

physical

+ +

Same as −P.

+ +

pipefail

+ +

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

+ + + + + + + +
+ + +

posix

 + + +

Enable posix mode; change the behavior of bash +where the default operation differs from the +POSIX standard to match the standard. See +SEE ALSO below for a reference to a +document that details how posix mode affects bash’s +behavior.

+ +

privileged

+ +

Same as −p.

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

verbose

 + + +

Same as −v.

+ + +

vi

 + + +

Use a vi-style command line editing interface. This also +affects the editing interface used for read +−e.

+ + +

xtrace

 + + +

Same as −x.

+ +

If −o is supplied +with no option−name, set prints the +current shell option settings. If +o is supplied with +no option−name, set prints a series of +set commands to recreate the current option settings +on the standard output.

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

−p

 + + +

Turn on privileged mode. +In this mode, the shell does not read the +$ENV and +$BASH_ENV files, shell functions are +not inherited from the environment, and the +SHELLOPTS, BASHOPTS, +CDPATH, and 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 +−p option is not supplied, these actions are +taken and the effective user id is set to the real user id. +If the −p option is supplied at startup, the +effective user id is not reset. Turning this option off +causes the effective user and group ids to be set to the +real user and group ids.

+ + +

−r

 + + +

Enable restricted shell mode. This option cannot be +unset once it has been set.

+ + +

−t

 + + +

Exit after reading and executing one command.

+ + +

−u

 + + +

Treat unset variables and parameters other than the +special parameters “@” and “*”, or +array variables subscripted with “@” or +“*”, 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.

+ + +

−v

 + + +

Print shell input lines as they are read.

+ + +

−x

 + + +

After expanding each simple command, for +command, case command, select command, or +arithmetic for command, display the expanded value of +PS4, followed by the +command and its expanded arguments or associated word list, +to the standard error.

+ + +

−B

 + + +

The shell performs brace expansion (see Brace +Expansion above). This is on by default.

+ + +

−C

 + + +

If set, bash does not overwrite an existing file +with the >, >&, and <> +redirection operators. Using the redirection operator +>| instead of > will override this and +force the creation of an output file.

+ + +

−E

 + + +

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

+ + +

−H

 + + +

Enable ! style history substitution. This option +is on by default when the shell is interactive.

+ + +

−P

 + + +

If set, the shell does not resolve symbolic links when +executing commands such as cd that change the current +working directory. It uses the physical directory structure +instead. By default, bash follows the logical chain +of directories when performing commands which change the +current directory.

+ + +

−T

 + + +

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

+ + +

−−

 + + +

If no arguments follow this option, unset the positional +parameters. Otherwise, set the positional parameters to the +args, even if some of them begin with a +−.

+ + +

−

 + + +

Signal the end of options, and assign all remaining +args to the positional parameters. The +−x and −v options are turned off. +If there are no args, the positional parameters +remain unchanged.

+ +

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 +$−. The return status is always zero unless an +invalid option is encountered.

+ +

shift [n]

+ +

Rename positional parameters +from n+1 ... to $1 .... Parameters represented +by the numbers $# down to $#−n+1 +are unset. n must be a non-negative number less than +or equal to $#. If n is 0, no parameters are +changed. If n is not given, it is assumed to be 1. If +n is greater than $#, the positional +parameters are not changed. The return status is greater +than zero if n is greater than $# or less than +zero; otherwise 0.

+ +

shopt +[−pqsu] [−o] [optname +...]

+ +

Toggle the values of settings +controlling optional shell behavior. The settings can be +either those listed below, or, if the −o option +is used, those available with the −o option to +the set builtin command.

+ +

With no +options, or with the −p option, display a list +of all settable options, with an indication of whether or +not each is set; if any optnames are supplied, the +output is restricted to those options. The −p +option displays output in a form that may be reused as +input.

+ +

Other options +have the following meanings:

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

−s

 + + +

Enable (set) each optname.

+ + +

−u

 + + +

Disable (unset) each optname.

+ + +

−q

 + + +

Suppresses normal output (quiet mode); the return status +indicates whether the optname is set or unset. If +multiple optname arguments are supplied with +−q, the return status is zero if all +optnames are enabled; non-zero otherwise.

+ + +

−o

 + + +

Restricts the values of optname to be those +defined for the −o option to the set +builtin.

+ +

If either +−s or −u is used with no +optname arguments, shopt shows only those +options which are set or unset, respectively. Unless +otherwise noted, the shopt options are disabled +(unset) by default.

+ +

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

+ +

The list of +shopt options is:
+array_expand_once

+ +

If set, the shell suppresses +multiple evaluation of associative and indexed array +subscripts during arithmetic expression evaluation, while +executing builtins that can perform variable assignments, +and while executing builtins that perform array +dereferencing.

+ +

assoc_expand_once

+ +

Deprecated; a synonym for +array_expand_once.

+ + + + + + + +
+ + +

autocd

 + + +

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

+ + +

bash_source_fullpath

+ +

If set, filenames added to the +BASH_SOURCE array variable are converted to full +pathnames (see Shell Variables above).

+ +

cdable_vars

+ +

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

+ + + + + + + +
+ + +

cdspell

 + + +

If set, the cd command attempts to correct minor +errors in the spelling of a directory component. Minor +errors include transposed characters, a missing character, +and one extra character. If cd corrects the directory +name, it prints the corrected filename, and the command +proceeds. This option is only used by interactive +shells.

+ +

checkhash

+ +

If set, bash checks that +a command found in the hash table exists before trying to +execute it. If a hashed command no longer exists, +bash performs a normal path search.

+ +

checkjobs

+ +

If set, bash lists the +status of any stopped and running jobs before exiting an +interactive shell. If any jobs are running, bash +defers the exit until a second exit is attempted without an +intervening command (see JOB CONTROL +above). The shell always postpones exiting if any jobs are +stopped.

+ +

checkwinsize

+ +

If set, bash checks the +window size after each external (non-builtin) command and, +if necessary, updates the values of +LINES and +COLUMNS, using the file +descriptor associated with the standard error if it is a +terminal. This option is enabled by default.

+ + + + + + + +
+ + +

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. This option is +enabled by default, but only has an effect if command +history is enabled, as described above under +HISTORY.

+ +

compat31
+compat32
+compat40
+compat41
+compat42
+compat43
+compat44

+ +

These control aspects of the +shell’s compatibility mode (see SHELL +COMPATIBILITY MODE below).

+ +

complete_fullquote

+ +

If set, bash quotes all +shell metacharacters in filenames and directory names when +performing completion. If not set, bash removes +metacharacters such as the dollar sign from the set of +characters that will be quoted in completed filenames when +these metacharacters appear in shell variable references in +words to be completed. This means that dollar signs in +variable names that expand to directories will not be +quoted; however, any dollar signs appearing in filenames +will not be quoted, either. This is active only when bash is +using backslashes to quote completed filenames. This +variable is set by default, which is the default bash +behavior in versions through 4.2.

+ +

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.

+ +

dirspell

+ +

If set, bash attempts +spelling correction on directory names during word +completion if the directory name initially supplied does not +exist.

+ + + + + + + +
+ + +

dotglob

 + + +

If set, bash includes filenames beginning with a +“.” in the results of pathname expansion. The +filenames . and .. must always be matched +explicitly, even if dotglob is set.

+ +

execfail

+ +

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

+ +

expand_aliases

+ +

If set, aliases are expanded as +described above under +ALIASES. This option is +enabled by default for interactive shells.

+ +

extdebug

+ +

If set at shell invocation, or +in a shell startup file, arrange to execute the debugger +profile before the shell starts, identical to the +−−debugger option. If set after +invocation, behavior intended for use by debuggers is +enabled:

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

1.

 + + +

The −F option to the declare builtin +displays the source file name and line number corresponding +to each function name supplied as an argument.

+ + +

2.

 + + +

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

+ + +

3.

 + + +

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

+ + +

4.

 + + +

BASH_ARGC and +BASH_ARGV are updated as described in +their descriptions above).

+ + +

5.

 + + +

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

+ + +

6.

 + + +

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

+ + +

extglob

 +
+ +

If set, enable +the extended pattern matching features described above under +Pathname Expansion.

+ +

extquote

+ +

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

+ +

failglob

+ +

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

+ +

force_fignore

+ +

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

+ +

globasciiranges

+ +

If set, range expressions used +in pattern matching bracket expressions (see +Pattern Matching above) behave as if +in the traditional C locale when performing comparisons. +That is, pattern matching does not take the current +locale’s collating sequence into account, so b +will not collate between A and B, and +upper-case and lower-case ASCII characters will collate +together.

+ +

globskipdots

+ +

If set, pathname expansion will +never match the filenames . and .., even if +the pattern begins with a “.”. This option is +enabled by default.

+ +

globstar

+ +

If set, the pattern ** +used in a pathname expansion context will match all files +and zero or more directories and subdirectories. If the +pattern is followed by a /, only directories and +subdirectories match.

+ +

gnu_errfmt

+ +

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

+ +

histappend

+ +

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

+ +

histreedit

+ +

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

+ +

histverify

+ +

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

+ +

hostcomplete

+ +

If set, and readline is +being used, bash will attempt to perform hostname +completion when a word containing a @ is being +completed (see Completing under +READLINE above). This is enabled by +default.

+ +

huponexit

+ +

If set, bash will send +SIGHUP to all jobs when an interactive +login shell exits.

+ +

inherit_errexit

+ +

If set, command substitution +inherits the value of the errexit option, instead of +unsetting it in the subshell environment. This option is +enabled when posix mode is enabled.

+ + +

interactive_comments

+ +

In an interactive shell, a word +beginning with # causes that word and all remaining +characters on that line to be ignored, as in a +non-interactive shell (see COMMENTS +above). This option is enabled by default.

+ +

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.

+ + + + + + + +
+ + +

lithist

 + + +

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

+ +

localvar_inherit

+ +

If set, local variables inherit +the value and attributes of a variable of the same name that +exists at a previous scope before any new value is assigned. +The nameref attribute is not inherited.

+ +

localvar_unset

+ +

If set, calling unset on +local variables in previous function scopes marks them so +subsequent lookups find them unset until that function +returns. This is identical to the behavior of unsetting +local variables at the current function scope.

+ +

login_shell

+ +

The shell sets this option if +it is started as a login shell (see +INVOCATION above). The value may not +be changed.

+ +

mailwarn

+ +

If set, and a file that +bash is checking for mail has been accessed since the +last time it was checked, bash displays the message +“The mail in mailfile has been read”.

+ + +

no_empty_cmd_completion

+ +

If set, and readline is +being used, bash does not search +PATH for possible completions when +completion is attempted on an empty line.

+ +

nocaseglob

+ +

If set, bash matches +filenames in a case−insensitive fashion when +performing pathname expansion (see Pathname Expansion +above).

+ +

nocasematch

+ +

If set, bash matches +patterns in a case−insensitive fashion when performing +matching while executing case or [[ +conditional commands, when performing pattern substitution +word expansions, or when filtering possible completions as +part of programmable completion.

+ + +

noexpand_translation

+ +

If set, bash encloses +the translated results of $"..." +quoting in single quotes instead of double quotes. If the +string is not translated, this has no effect.

+ +

nullglob

+ +

If set, pathname expansion +patterns which match no files (see Pathname Expansion +above) expand to nothing and are removed, rather than +expanding to themselves.

+ +

patsub_replacement

+ +

If set, bash expands +occurrences of & in the replacement string of +pattern substitution to the text matched by the pattern, as +described under Parameter Expansion above. This +option is enabled by default.

+ +

progcomp

+ +

If set, enable the programmable +completion facilities (see Programmable Completion +above). This option is enabled by default.

+ +

progcomp_alias

+ +

If set, and programmable +completion is enabled, bash treats a command name +that doesn’t have any completions as a possible alias +and attempts alias expansion. If it has an alias, +bash attempts programmable completion using the +command word resulting from the expanded alias.

+ +

promptvars

+ +

If set, prompt strings undergo +parameter expansion, command substitution, arithmetic +expansion, and quote removal after being expanded as +described in PROMPTING above. This +option is enabled by default.

+ +

restricted_shell

+ +

The shell sets this option if +it is started in restricted mode (see 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.

+ +

shift_verbose

+ +

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

+ +

sourcepath

+ +

If set, the . +(source) builtin uses the value of +PATH to find the directory containing +the file supplied as an argument when the −p +option is not supplied. This option is enabled by +default.

+ +

varredir_close

+ +

If set, the shell automatically +closes file descriptors assigned using the {varname} +redirection syntax (see REDIRECTION +above) instead of leaving them open when the command +completes.

+ +

xpg_echo

+ +

If set, the echo builtin +expands backslash-escape sequences by default. If the +posix shell option is also enabled, echo does +not interpret any options.

+ +

suspend +[−f]

+ +

Suspend the execution of this +shell until it receives a SIGCONT +signal. A login shell, or a shell without job control +enabled, cannot be suspended; the −f option +will override this and force the suspension. The return +status is 0 unless the shell is a login shell or job control +is not enabled and −f is not supplied.

+ +

test expr
+[ expr ]

+ +

Return a status of 0 (true) or +1 (false) depending on the evaluation of the conditional +expression expr. Each operator and operand must be a +separate argument. Expressions are composed of the primaries +described above under CONDITIONAL +EXPRESSIONS. test does not +accept any options, nor does it accept and ignore an +argument of −− as signifying the end of +options.

+ +

Expressions may +be combined using the following operators, listed in +decreasing order of precedence. The evaluation depends on +the number of arguments; see below. test uses +operator precedence when there are five or more +arguments.

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

! expr

 + + +

True if expr is false.

 +
+ +

( expr +)

+ +

Returns the value of +expr. This may be used to override normal operator +precedence.

+ +

expr1 −a +expr2

+ +

True if both expr1 and +expr2 are true.

+ +

expr1 −o +expr2

+ +

True if either expr1 or +expr2 is true.

+ +

test and +[ evaluate conditional expressions using a set of +rules based on the number of arguments.
+0 arguments

+ +

The expression is false.

+ +

1 argument

+ +

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

+ +

2 arguments

+ +

If the first argument is +!, the expression is true if and only if the second +argument is null. If the first argument is one of the unary +conditional operators listed above under +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.

+ +

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 +CONDITIONAL +EXPRESSIONS, the result of the +expression is the result of the binary test using the first +and third arguments as operands. The −a and +−o operators are considered binary operators +when there are three arguments. If the first argument is +!, the value is the negation of the two-argument test +using the second and third arguments. If the first argument +is exactly ( and the third argument is exactly +), the result is the one-argument test of the second +argument. Otherwise, the expression is false.

+ +

4 arguments

+ +

The following conditions are +applied in the order listed. If the first argument is +!, the result is the negation of the three-argument +expression composed of the remaining arguments. If the first +argument is exactly ( and the fourth argument is +exactly ), the result is the two-argument test of the +second and third arguments. Otherwise, the expression is +parsed and evaluated according to precedence using the rules +listed above.

+ +

5 or more arguments

+ +

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

+ +

When the shell +is in posix mode, or if the expression is part of the +[[ command, the < and > operators +sort using the current locale. If the shell is not in posix +mode, the test and [ commands sort +lexicographically using ASCII ordering.

+ +

The historical +operator-precedence parsing with 4 or more arguments can +lead to ambiguities when it encounters strings that look +like primaries. The POSIX standard has +deprecated the −a and −o primaries +and enclosing expressions within parentheses. Scripts should +no longer use them. It’s much more reliable to +restrict test invocations to a single primary, and to +replace uses of −a and −o with the +shell’s && and || list +operators.

+ + + + + + + +
+ + +

times

 + + +

Print the accumulated user and system times for the +shell and for processes run from the shell. The return +status is 0.

+ +

trap [−lpP] +[[action] sigspec ...]

+ +

The action is a command +that is read and executed when the shell receives any of the +signals sigspec. If action is absent (and +there is a single sigspec) or −, each +specified sigspec is reset to the value it had when +the shell was started. If action is the null string +the signal specified by each sigspec is ignored by +the shell and by the commands it invokes.

+ +

If no arguments +are supplied, trap displays the actions associated +with each trapped signal as a set of trap commands +that can be reused as shell input to restore the current +signal dispositions. If −p is given, and +action is not present, then trap displays the +actions associated with each sigspec or, if none are +supplied, for all trapped signals, as a set of trap +commands that can be reused as shell input to restore the +current signal dispositions. The −P option +behaves similarly, but displays only the actions associated +with each sigspec argument. −P requires +at least one sigspec argument. The −P or +−p options may be used in a subshell +environment (e.g., command substitution) and, as long as +they are used before trap is used to change a +signal’s handling, will display the state of its +parent’s traps.

+ +

The +−l option prints a list of signal names and +their corresponding numbers. Each sigspec is either a +signal name defined in <signal.h>, or a signal +number. Signal names are case insensitive and the +SIG prefix is optional. If +−l is supplied with no sigspec +arguments, it prints a list of valid signal names.

+ +

If a +sigspec is EXIT (0), +action is executed on exit from the shell. If a +sigspec is +DEBUG, action is +executed before every simple command, for +command, case command, select command, (( +arithmetic command, [[ conditional command, arithmetic +for command, and before the first command executes in +a shell function (see SHELL GRAMMAR +above). Refer to the description of the extdebug +shell option (see shopt above) for details of its +effect on the DEBUG trap. If a sigspec is +RETURN, action +is executed each time a shell function or a script executed +with the . or source builtins finishes +executing.

+ +

If a +sigspec is ERR, +action is executed whenever a pipeline (which may +consist of a single simple command), a list, or a compound +command returns a non−zero exit status, subject to the +following conditions. The ERR trap is +not executed if the failed command is part of the command +list immediately following a while or until +reserved word, part of the test in an if statement, +part of a command executed in a && or +|| list except the command following the final +&& or ||, any command in a pipeline +but the last (subject to the state of the pipefail +shell option), or if the command’s return value is +being inverted using !. These are the same conditions +obeyed by the errexit (−e) option.

+ +

When the shell +is not interactive, signals ignored upon entry to the shell +cannot be trapped or reset. Interactive shells permit +trapping signals ignored on entry. 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 sigspec is invalid; +otherwise trap returns true.

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

true

 + + +

Does nothing, returns a 0 status.

 +
+ +

type +[−aftpP] name [name ...]

+ +

Indicate how each name +would be interpreted if used as a command name.

+ +

If the +−t option is used, type prints a string +which is one of alias, keyword, +function, builtin, or file if +name is an alias, shell reserved word, function, +builtin, or executable file, respectively. If the +name is not found, type prints nothing and +returns a non-zero exit status.

+ +

If the +−p option is used, type either returns +the pathname of the executable file that would be found by +searching $PATH for name or nothing if +“type −t name” would not return +file. The −P option forces a +PATH search for each name, even +if “type −t name” would not return +file. If name is present in the table of +hashed commands, −p and −P print +the hashed value, which is not necessarily the file that +appears first in +PATH.

+ +

If the +−a option is used, type prints all of +the places that contain a command named name. This +includes aliases, reserved words, functions, and builtins, +but the path search options (−p and +−P) can be supplied to restrict the output to +executable files. type does not consult the table of +hashed commands when using −a with +−p, and only performs a +PATH search for name.

+ +

The +−f option suppresses shell function lookup, as +with the command builtin. type returns true if +all of the arguments are found, false if any are not +found.

+ +

ulimit [−HS] +−a
+ulimit [−HS] +[−bcdefiklmnpqrstuvxPRT [limit]]

+ +

Provides control over the +resources available to the shell and to processes it starts, +on systems that allow such control.

+ +

The +−H and −S options specify whether +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 −H nor −S is +specified, ulimit sets both the soft and hard +limits.

+ +

The value of +limit can be a number in the unit specified for the +resource or one of the special values hard, +soft, or unlimited, which stand for the +current hard limit, the current soft limit, and no limit, +respectively. If limit is omitted, ulimit +prints the current value of the soft limit of the resource, +unless the −H option is given. When more than +one resource is specified, the limit name and unit, if +appropriate, are printed before the value. Other options are +interpreted as follows:

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

−a

 + + +

Report all current limits; no limits are set.

+ + +

−b

 + + +

The maximum socket buffer size.

+ + +

−c

 + + +

The maximum size of core files created.

+ + +

−d

 + + +

The maximum size of a process’s data segment.

+ + +

−e

 + + +

The maximum scheduling priority +(“nice”).

+ + +

−f

 + + +

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

+ + +

−i

 + + +

The maximum number of pending signals.

+ + +

−k

 + + +

The maximum number of kqueues that may be allocated.

+ + +

−l

 + + +

The maximum size that may be locked into memory.

+ + +

−m

 + + +

The maximum resident set size (many systems do not honor +this limit).

+ + +

−n

 + + +

The maximum number of open file descriptors (most +systems do not allow this value to be set).

+ + +

−p

 + + +

The pipe size in 512-byte blocks (this may not be +set).

+ + +

−q

 + + +

The maximum number of bytes in POSIX +message queues.

+ + +

−r

 + + +

The maximum real-time scheduling priority.

+ + +

−s

 + + +

The maximum stack size.

+ + +

−t

 + + +

The maximum amount of cpu time in seconds.

+ + +

−u

 + + +

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

+ + +

−v

 + + +

The maximum amount of virtual memory available to the +shell and, on some systems, to its children.

+ + +

−x

 + + +

The maximum number of file locks.

+ + +

−P

 + + +

The maximum number of pseudoterminals.

+ + +

−R

 + + +

The maximum time a real-time process can run before +blocking, in microseconds.

+ + +

−T

 + + +

The maximum number of threads.

+ +

If limit +is supplied, and the −a option is not used, +limit is the new value of the specified resource. If +no option is supplied, then −f is assumed.

+ +

Values are in +1024-byte increments, except for −t, which is +in seconds; −R, which is in microseconds; +−p, which is in units of 512-byte blocks; +−P, −T, −b, +−k, −n, and −u, which +are unscaled values; and, when in posix mode, +−c and −f, which are in 512-byte +increments. The return status is 0 unless an invalid option +or argument is supplied, or an error occurs while setting a +new limit.

+ +

umask [−p] +[−S] [mode]

+ +

Set the user file-creation mask +to mode. If 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 +chmod(1). If mode is omitted, umask +prints the current value of the mask. The −S +option without a mode argument prints the mask in a +symbolic format; the default output is an octal number. If +the −p option is supplied, and mode is +omitted, the output is in a form that may be reused as +input. The return status is zero if the mode was +successfully changed or if no mode argument was +supplied, and non-zero otherwise.

+ +

unalias [−a] +[name ...]

+ +

Remove each name from +the list of defined aliases. If −a is supplied, +remove all alias definitions. The return value is true +unless a supplied name is not a defined alias.

+ +

unset [−fv] +[−n] [name ...]

+ +

For each name, remove +the corresponding variable or function. If the +−v option is given, each name refers to +a shell variable, and that variable is removed. If +−f is specified, each name refers to a +shell function, and the function definition is removed. If +the −n option is supplied, and name is a +variable with the nameref attribute, name will +be unset rather than the variable it references. +−n has no effect if the −f option +is supplied. Read-only variables and functions may not be +unset. When variables or functions are removed, they are +also removed from the environment passed to subsequent +commands. If no options are supplied, each name +refers to a variable; if there is no variable by that name, +a function with that name, if any, is unset. Some shell +variables may not be unset. If any of +BASH_ALIASES, +BASH_ARGV0, BASH_CMDS, BASH_COMMAND, +BASH_SUBSHELL, BASHPID, +COMP_WORDBREAKS, DIRSTACK, +EPOCHREALTIME, EPOCHSECONDS, FUNCNAME, +GROUPS, HISTCMD, LINENO, RANDOM, +SECONDS, or SRANDOM are +unset, they lose their special properties, even if they are +subsequently reset. The exit status is true unless a +name is readonly or may not be unset.

+ +

wait [−fn] +[−p varname] [id ...]

+ +

Wait for each specified child +process id and return the termination status of the +last id. Each id may be a process ID +pid or a job specification jobspec; if a +jobspec is supplied, wait waits for all processes in +the job.

+ +

If no options +or ids are supplied, wait waits for all +running background jobs and the last-executed process +substitution, if its process id is the same as $!, +and the return status is zero.

+ +

If the +−n option is supplied, wait waits for +any one of the given ids or, if no ids are +supplied, any job or process substitution, to complete and +returns its exit status. If none of the supplied ids +is a child of the shell, or if no ids are supplied +and the shell has no unwaited-for children, the exit status +is 127.

+ +

If the +−p option is supplied, wait assigns the +process or job identifier of the job for which the exit +status is returned to the variable varname named by +the option argument. The variable, which cannot be readonly, +will be unset initially, before any assignment. This is +useful only when used with the −n option.

+ +

Supplying the +−f option, when job control is enabled, forces +wait to wait for each id to terminate before +returning its status, instead of returning when it changes +status.

+ +

If none of the +ids specify one of the shell’s active child +processes, the return status is 127. If wait is +interrupted by a signal, any varname will remain +unset, and the return status will be greater than 128, as +described under SIGNALS above. Otherwise, the return +status is the exit status of the last id.

+ +

SHELL COMPATIBILITY MODE + +

+ + +

Bash-4.0 +introduced the concept of a shell compatibility +level, specified as a set of options to the shopt +builtin (compat31, compat32, compat40, +compat41, and so on). There is only one current +compatibility level — each option is mutually +exclusive. The compatibility level is intended to allow +users to select behavior from previous versions that is +incompatible with newer versions while they migrate scripts +to use current features and behavior. It’s intended to +be a temporary solution.

+ +

This section +does not mention behavior that is standard for a particular +version (e.g., setting compat32 means that quoting +the right hand side of the regexp matching operator quotes +special regexp characters in the word, which is default +behavior in bash-3.2 and subsequent versions).

+ +

If a user +enables, say, compat32, it may affect the behavior of +other compatibility levels up to and including the current +compatibility level. The idea is that each compatibility +level controls behavior that changed in that version of +bash, but that behavior may have been present in +earlier versions. For instance, the change to use +locale-based comparisons with the [[ command came in +bash-4.1, and earlier versions used ASCII-based comparisons, +so enabling compat32 will enable ASCII-based +comparisons as well. That granularity may not be sufficient +for all uses, and as a result users should employ +compatibility levels carefully. Read the documentation for a +particular feature to find out the current behavior.

+ +

Bash-4.3 +introduced a new shell variable: +BASH_COMPAT. The value +assigned to this variable (a decimal version number like +4.2, or an integer corresponding to the +compatNN option, like 42) determines the +compatibility level.

+ +

Starting with +bash-4.4, bash began deprecating older compatibility +levels. Eventually, the options will be removed in favor of +BASH_COMPAT.

+ +

Bash-5.0 was the +final version for which there was an individual shopt option +for the previous version. BASH_COMPAT +is the only mechanism to control the compatibility level in +versions newer than bash-5.0.

+ +

The following +table describes the behavior changes controlled by each +compatibility level setting. The compatNN tag +is used as shorthand for setting the compatibility level to +NN using one of the following mechanisms. For +versions prior to bash-5.0, the compatibility level may be +set using the corresponding compatNN shopt +option. For bash-4.3 and later versions, the +BASH_COMPAT variable is preferred, and +it is required for bash-5.1 and later versions.
+compat31

+ + + + + + + +
+ + +

•

 + + +

Quoting the rhs of the [[ command’s regexp +matching operator (=~) has no special effect.

+ +

compat32

+ + + + + + + +
+ + +

•

 + + +

The < and > operators to the +[[ command do not consider the current locale when +comparing strings; they use ASCII ordering.

+ +

compat40

+ + + + + + + +
+ + +

•

 + + +

The < and > operators to the +[[ command do not consider the current locale when +comparing strings; they use ASCII ordering. Bash +versions prior to bash-4.1 use ASCII collation and +strcmp(3); bash-4.1 and later use the current +locale’s collation sequence and strcoll(3).

+ +

compat41

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

•

 + + +

In posix mode, time may be followed by options +and still be recognized as a reserved word (this is +POSIX interpretation 267).

+ + +

•

 + + +

In posix mode, the parser requires that an even +number of single quotes occur in the word portion of +a double-quoted parameter expansion and treats them +specially, so that characters within the single quotes are +considered quoted (this is POSIX +interpretation 221).

+ +

compat42

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

•

 + + +

The replacement string in double-quoted pattern +substitution does not undergo quote removal, as it does in +versions after bash-4.2.

+ + +

•

 + + +

In posix mode, single quotes are considered special when +expanding the word portion of a double-quoted +parameter expansion and can be used to quote a closing brace +or other special character (this is part of +POSIX interpretation 221); in later versions, +single quotes are not special within double-quoted word +expansions.

+ +

compat43

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

•

 + + +

Word expansion errors are considered non-fatal errors +that cause the current command to fail, even in posix mode +(the default behavior is to make them fatal errors that +cause the shell to exit).

+ + +

•

 + + +

When executing a shell function, the loop state +(while/until/etc.) is not reset, so break or +continue in that function will break or continue +loops in the calling context. Bash-4.4 and later reset the +loop state to prevent this.

+ +

compat44

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

•

 + + +

The shell sets up the values used by +BASH_ARGV and +BASH_ARGC so they can expand to the +shell’s positional parameters even if extended +debugging mode is not enabled.

+ + +

•

 + + +

A subshell inherits loops from its parent context, so +break or continue will cause the subshell to +exit. Bash-5.0 and later reset the loop state to prevent the +exit

+ + +

•

 + + +

Variable assignments preceding builtins like +export and readonly that set attributes +continue to affect variables with the same name in the +calling environment even if the shell is not in posix +mode.

+ +

compat50

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

•

 + + +

Bash-5.1 changed the way $RANDOM +is generated to introduce slightly more randomness. If the +shell compatibility level is set to 50 or lower, it reverts +to the method from bash-5.0 and previous versions, so +seeding the random number generator by assigning a value to +RANDOM will produce the same sequence +as in bash-5.0.

+ + +

•

 + + +

If the command hash table is empty, bash versions prior +to bash-5.1 printed an informational message to that effect, +even when producing output that can be reused as input. +Bash-5.1 suppresses that message when the −l +option is supplied.

+ +

compat51

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

•

 + + +

The unset builtin treats attempts to unset array +subscripts @ and * differently depending on +whether the array is indexed or associative, and differently +than in previous versions.

+ + +

•

 + + +

Arithmetic commands ( ((...)) ) and the +expressions in an arithmetic for statement can be expanded +more than once.

+ + +

•

 + + +

Expressions used as arguments to arithmetic operators in +the [[ conditional command can be expanded more than +once.

+ + +

•

 + + +

The expressions in substring parameter brace expansion +can be expanded more than once.

+ + +

•

 + + +

The expressions in the $((...)) word +expansion can be expanded more than once.

+ + +

•

 + + +

Arithmetic expressions used as indexed array subscripts +can be expanded more than once.

+ + +

•

 + + +

test −v, when given an argument of +A[@], where A is an existing associative +array, will return true if the array has any set elements. +Bash-5.2 will look for and report on a key named +@.

+ + +

•

 + + +

The ${parameter[:]=value} word +expansion will return value, before any +variable-specific transformations have been performed (e.g., +converting to lowercase). Bash-5.2 will return the final +value assigned to the variable.

+ + +

•

 + + +

Parsing command substitutions will behave as if extended +globbing (see the description of the shopt builtin +above) is enabled, so that parsing a command substitution +containing an extglob pattern (say, as part of a shell +function) will not fail. This assumes the intent is to +enable extglob before the command is executed and word +expansions are performed. It will fail at word expansion +time if extglob hasn’t been enabled by the time the +command is executed.

+ +

compat52

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

•

 + + +

The test builtin uses its historical algorithm to +parse parenthesized subexpressions when given five or more +arguments.

+ + +

•

 + + +

If the −p or −P option is +supplied to the bind builtin, bind treats any +arguments remaining after option processing as bindable +command names, and displays any key sequences bound to those +commands, instead of treating the arguments as key sequences +to bind.

+ +

RESTRICTED SHELL + +

+ + +

If bash +is started with the name rbash, or the +−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 bash with the exception +that the following are disallowed or not performed:

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

•

 + + +

Changing directories with +cd.

+ + +

•

 + + +

Setting or unsetting the values of +SHELL, PATH, +HISTFILE, ENV, or +BASH_ENV.

+ + +

•

 + -with --p, - -and only performs a -PATH - - -search for name. -
-The --f - -option suppresses shell function lookup, as with the command builtin. -type - -returns true if all of the arguments are found, false if -any are not found. -
ulimit [-HS] -a
- -
ulimit [-HS] [-bcdefiklmnpqrstuvxPRT [limit]]
- -Provides control over the resources available to the shell and to -processes it starts, on systems that allow such control. -
-The -H and -S options specify whether -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 -H nor -S is specified, -ulimit sets both the soft and hard limits. -
-The value of -limit - -can be a number in the unit specified for the resource -or one of the special values -hard, - -soft, - -or -unlimited, - -which stand for the current hard limit, the current soft limit, and -no limit, respectively. -If -limit - -is omitted, ulimit prints the current value of the soft limit of -the resource, unless the -H option is given. -When more than one resource is specified, the limit name and unit, -if appropriate, are printed before the value. -Other options are interpreted as follows: -
- -
-
-a - -
-Report all current limits; no limits are set. -
-b - -
-The maximum socket buffer size. -
-c - -
-The maximum size of core files created. -
-d +

Specifying command names containing /.

-
-The maximum size of a process's data segment. -
-e -
-The maximum scheduling priority ( +

•

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

Specifying a filename containing a / as an +argument to the . builtin command.

-
-The maximum number of pending signals. -
-k -
-The maximum number of kqueues that may be allocated. -
-l +

•

 -
-The maximum size that may be locked into memory. -
-m -
-The maximum resident set size (many systems do not honor this limit). -
-n +

Using the −p option to the . builtin +command to specify a search path.

-
-The maximum number of open file descriptors (most systems do not -allow this value to be set). -
-p -
-The pipe size in 512-byte blocks (this may not be set). -
-q +

•

 -
-The maximum number of bytes in -POSIX -message queues. -
-r -
-The maximum real-time scheduling priority. -
-s +

Specifying a filename containing a slash as an argument +to the history builtin command.

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

•

 -
-The maximum number of processes available to a single user. -
-v -
-The maximum amount of virtual memory available to the shell and, on -some systems, to its children. -
-x +

Specifying a filename containing a slash as an argument +to the −p option to the hash builtin +command.

-
-The maximum number of file locks. -
-P -
-The maximum number of pseudoterminals. -
-R +

•

 -
-The maximum time a real-time process can run before blocking, in microseconds. -
-T -
-The maximum number of threads. +

Importing function definitions from the shell +environment at startup.

- -

-If -limit +

•

 -is supplied, and the --a -option is not used, -limit is the new value of the specified resource. -If no option is supplied, then --f +

Parsing the values of BASHOPTS and +SHELLOPTS from the shell environment +at startup.

-is assumed. -

-Values are in 1024-byte increments, except for --t, +

•

 -which is in seconds; --R, -which is in microseconds; --p, +

Redirecting output using the >, >|, <>, +>&, &>, and >> redirection +operators.

-which is in units of 512-byte blocks; --P, --T, +

•

 --b, --k, +

Using the exec builtin command to replace the +shell with another command.

--n, -and --u, +

•

 -which are unscaled values; -and, when in posix mode, --c -and --f, +

Adding or deleting builtin commands with the +−f and −d options to the +enable builtin command.

-which are in 512-byte increments. -The return status is 0 unless an invalid option or argument is supplied, -or an error occurs while setting a new limit. - -
umask [-p] [-S] [mode]
-Set the user file-creation mask to -mode. +

•

 -If -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 -chmod(1). +

Using the enable builtin command to enable +disabled shell builtins.

-If -mode -is omitted, umask prints the current value of the mask. -The --S +

•

 -option without a mode argument -prints the mask in a symbolic format; -the default output is an octal number. -If the --p -option is supplied, and -mode +

Specifying the −p option to the +command builtin command.

-is omitted, the output is in a form that may be reused as input. -The return status is zero if the mode was successfully changed or -if no mode argument was supplied, and non-zero otherwise. -
unalias [-a] [name ...]
-Remove each name from the list of defined aliases. -If --a -is supplied, remove all alias definitions. -The return value is true unless a supplied -name +

•

 -is not a defined alias. -
unset [-fv] [-n] [name ...]
-For each -name, -remove the corresponding variable or function. -If the --v +

Turning off restricted mode with set +r or +shopt −u restricted_shell.

-option is given, each -name - -refers to a shell variable, and that variable is removed. -If --f - -is specified, each -name - -refers to a shell function, and the function definition -is removed. -If the --n - -option is supplied, and name is a variable with the nameref -attribute, name will be unset rather than the variable it -references. --n has no effect if the -f option is supplied. -Read-only variables and functions may not be unset. -When variables or functions are removed, they are also removed -from the environment passed to subsequent commands. -If no options are supplied, each name refers to a variable; if -there is no variable by that name, a function with that name, if any, is -unset. -Some shell variables may not be unset. -If any of -BASH_ALIASES, - - -BASH_ARGV0, - - -BASH_CMDS, - - -BASH_COMMAND, - - -BASH_SUBSHELL, - - -BASHPID, - - -COMP_WORDBREAKS, - - -DIRSTACK, - - -EPOCHREALTIME, - - -EPOCHSECONDS, - - -FUNCNAME, - - -GROUPS, - - -HISTCMD, - - -LINENO, - - -RANDOM, - - -SECONDS, - - -or -SRANDOM - - -are unset, they lose their special properties, even if they are -subsequently reset. -The exit status is true unless a -name - -is readonly or may not be unset. -
wait [-fn] [-p varname] [id ...]
-Wait for each specified child process id and return the -termination status of the last id. -Each id may be a process ID pid -or a job specification jobspec; -if a jobspec is supplied, wait waits for all processes in the job. -
-If no options or ids are supplied, -wait waits for all running background jobs and -the last-executed process substitution, -if its process id is the same as $!, -and the return status is zero. -
-If the -n option is supplied, wait waits for any one of -the given ids or, -if no ids are supplied, any job or process substitution, -to complete and returns its exit status. -If none of the supplied ids is a child of the shell, -or if no ids are supplied and the shell has no unwaited-for children, -the exit status is 127. -
-If the -p option is supplied, wait assigns -the process or job identifier of the job -for which the exit status is returned to the -variable varname named by the option argument. -The variable, -which cannot be readonly, -will be unset initially, before any assignment. -This is useful only when used with the -n option. -
-Supplying the -f option, when job control is enabled, -forces wait to wait for each id to terminate before -returning its status, instead of returning when it changes status. -
-If none of the ids specify one of the shell's active child -processes, the return status is 127. -If wait is interrupted by a signal, -any varname will remain unset, -and the return status will be greater -than 128, as described under -SIGNALS - - -above. -Otherwise, the return status is the exit status of the last id. - -  -

SHELL COMPATIBILITY MODE

- -Bash-4.0 introduced the concept of a shell compatibility level, -specified as a set of options to the shopt builtin ( -compat31, - -compat32, - -compat40, - -compat41, - -and so on). -There is only one current -compatibility level - each option is mutually exclusive. -The compatibility level is intended to allow users to select behavior -from previous versions that is incompatible with newer versions -while they migrate scripts to use current features and behavior. -It's intended to be a temporary solution. -

- -This section does not mention behavior that is standard for a particular -version (e.g., setting compat32 means that quoting the right hand -side of the regexp -matching operator quotes special regexp characters in the word, which is -default behavior in bash-3.2 and subsequent versions). -

- -If a user enables, say, compat32, it may affect the behavior of other -compatibility levels up to and including the current compatibility level. -The idea is that each compatibility level controls behavior that changed -in that version of bash, -but that behavior may have been present in earlier versions. -For instance, the change to use locale-based comparisons with the [[ -command came in bash-4.1, and earlier versions used ASCII-based comparisons, -so enabling compat32 will enable ASCII-based comparisons as well. -That granularity may not be sufficient for -all uses, and as a result users should employ compatibility levels carefully. -Read the documentation for a particular feature to find out the -current behavior. -

- -Bash-4.3 introduced a new shell variable: -BASH_COMPAT. - - -The value assigned -to this variable (a decimal version number like 4.2, or an integer -corresponding to the compatNN option, like 42) determines the -compatibility level. -

- -Starting with bash-4.4, bash began deprecating older compatibility -levels. -Eventually, the options will be removed in favor of -BASH_COMPAT. - - -

- -Bash-5.0 was the final version for which there was an individual shopt -option for the previous version. -BASH_COMPAT - - -is the only mechanism to control the compatibility level -in versions newer than bash-5.0. -

- -The following table describes the behavior changes controlled by each -compatibility level setting. -The compatNN tag is used as shorthand for setting the -compatibility level -to NN using one of the following mechanisms. -For versions prior to bash-5.0, the compatibility level may be set using -the corresponding compatNN shopt option. -For bash-4.3 and later versions, the -BASH_COMPAT - - -variable is preferred, -and it is required for bash-5.1 and later versions. -

-
compat31
- -
-
-
*
-Quoting the rhs of the [[ command's regexp matching operator (=~) -has no special effect. -
- - -
compat32
- -
-
-
*
-The < and > operators to the [[ command do not -consider the current locale when comparing strings; they use ASCII -ordering. -
- - -
compat40
- -
-
-
*
-The < and > operators to the [[ command do not -consider the current locale when comparing strings; they use ASCII -ordering. -Bash versions prior to bash-4.1 use ASCII collation and -strcmp(3); - -bash-4.1 and later use the current locale's collation sequence and -strcoll(3). - -
- - -
compat41
- -
-
-
*
-In posix mode, time may be followed by options and still be -recognized as a reserved word (this is -POSIX -interpretation 267). -
*
-In posix mode, the parser requires that an even number of single -quotes occur in the word portion of a double-quoted -parameter expansion and treats them specially, so that characters within -the single quotes are considered quoted -(this is -POSIX -interpretation 221). -
- - -
compat42
- -
-
-
*
-The replacement string in double-quoted pattern substitution does not -undergo quote removal, as it does in versions after bash-4.2. -
*
-In posix mode, single quotes are considered special when expanding -the word portion of a double-quoted parameter expansion -and can be used to quote a closing brace or other special character -(this is part of -POSIX -interpretation 221); -in later versions, single quotes -are not special within double-quoted word expansions. -
- - -
compat43
- -
-
-
*
-Word expansion errors are considered non-fatal errors that cause the -current command to fail, even in posix mode -(the default behavior is to make them fatal errors that cause the shell -to exit). -
*
-When executing a shell function, the loop state (while/until/etc.) -is not reset, so break or continue in that function will break -or continue loops in the calling context. -Bash-4.4 and later reset the loop state to prevent this. -
- - -
compat44
- -
-
-
*
-The shell sets up the values used by -BASH_ARGV - - -and -BASH_ARGC - - -so they can expand to the shell's positional parameters even if extended -debugging mode is not enabled. -
*
-A subshell inherits loops from its parent context, so break -or continue will cause the subshell to exit. -Bash-5.0 and later reset the loop state to prevent the exit -
*
-Variable assignments preceding builtins like export and readonly -that set attributes continue to affect variables with the same -name in the calling environment even if the shell is not in posix -mode. -
- - -
compat50
- -
-
-
*
-Bash-5.1 changed the way -$RANDOM - - -is generated to introduce slightly more randomness. -If the shell compatibility level is set to 50 or -lower, it reverts to the method from bash-5.0 and previous versions, -so seeding the random number generator by assigning a value to -RANDOM - - -will produce the same sequence as in bash-5.0. -
*
-If the command hash table is empty, bash versions prior to bash-5.1 -printed an informational message to that effect, even when producing -output that can be reused as input. -Bash-5.1 suppresses that message -when the -l option is supplied. -
- - -
compat51
- -
-
-
*
-The unset builtin treats attempts to unset array subscripts @ -and * differently depending on whether the array is indexed or -associative, and differently than in previous versions. -
*
-Arithmetic commands ( -((...)) - -) and the expressions in an arithmetic for -statement can be expanded more than once. -
*
-Expressions used as arguments to arithmetic operators in the [[ -conditional command can be expanded more than once. -
*
-The expressions in substring parameter brace expansion can be -expanded more than once. -
*
-The expressions in the -$((...)) - -word expansion can be expanded more than once. -
*
-Arithmetic expressions used as indexed array subscripts can be -expanded more than once. -
*
-test -v, when given an argument of A[@], where A is -an existing associative array, will return true if the array has any set -elements. -Bash-5.2 will look for and report on a key named @. -
*
-The ${parameter[:]=value} word expansion will return -value, before any variable-specific transformations have been -performed (e.g., converting to lowercase). -Bash-5.2 will return the final value assigned to the variable. -
*
-Parsing command substitutions will behave as if extended globbing -(see the description of the -shopt - -builtin above) -is enabled, so that parsing a command substitution containing an extglob -pattern (say, as part of a shell function) will not fail. -This assumes the intent is to enable extglob before the command is executed -and word expansions are performed. -It will fail at word expansion time if extglob hasn't been -enabled by the time the command is executed. -
- - -
compat52
- -
-
-
*
-The test builtin uses its historical algorithm to parse parenthesized -subexpressions when given five or more arguments. -
*
-If the -p or -P option is supplied to the bind builtin, -bind treats any arguments remaining after option processing -as bindable command names, and -displays any key sequences bound to those commands, instead of treating -the arguments as key sequences to bind. -
- - - - -
-  -

RESTRICTED SHELL

- - - -

- -If -bash - -is started with the name -rbash, - -or the --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 -bash - -with the exception that the following are disallowed or not performed: -

-
*
-Changing directories with cd. -
*
-Setting or unsetting the values of -SHELL, - - -PATH, - - -HISTFILE, - - -ENV, - - -or -BASH_ENV. - - -
*
-Specifying command names containing -/. - -
*
-Specifying a filename containing a -/ - -as an argument to the -. - -builtin command. -
*
-Using the -p option to the -. +

These +restrictions are enforced after any startup files are +read.

-builtin command to specify a search path. -
*
-Specifying a filename containing a slash as an argument to the -history +

When a command +that is found to be a shell script is executed (see +COMMAND EXECUTION above), rbash +turns off any restrictions in the shell spawned to execute +the script.

-builtin command. -
*
-Specifying a filename containing a slash as an argument to the --p +

SEE ALSO + +

-option to the -hash -builtin command. -
*
-Importing function definitions from the shell environment at startup. -
*
-Parsing the values of -BASHOPTS +

Bash +Reference Manual, Brian Fox and Chet Ramey
+The Gnu Readline Library, Brian Fox and Chet Ramey +
+The Gnu History Library, Brian Fox and Chet Ramey +
+Portable Operating System Interface (POSIX) Part 2: Shell +and
+Utilities, IEEE —

- -and -SHELLOPTS - -from the shell environment at startup. -
*
-Redirecting output using the >, >|, <>, >&, &>, and >> redirection operators. -
*
-Using the -exec +

http://pubs.opengroup.org/onlinepubs/9799919799/

-builtin command to replace the shell with another command. -
*
-Adding or deleting builtin commands with the --f -and --d +

http://tiswww.case.edu/~chet/bash/POSIX +— a description of posix mode
+sh(1), ksh(1), csh(1)
+emacs(1), vi(1)
+readline(3)

-options to the -enable +

FILES + +

-builtin command. -
*
-Using the enable builtin command to enable disabled shell builtins. -
*
-Specifying the --p -option to the -command -builtin command. -
*
-Turning off restricted mode with -set +r or shopt -u restricted_shell. -
-

+

/bin/bash

-These restrictions are enforced after any startup files are read. -

+

The bash executable

+

/etc/profile

- When a command that is found to be a shell script is executed -(see -COMMAND EXECUTION +

The systemwide initialization +file, executed for login shells

- +

~/.bash_profile

-above), +

The personal initialization +file, executed for login shells

+

~/.bashrc

-rbash +

The individual +per-interactive-shell startup file

-turns off any restrictions in the shell spawned to execute the -script. +

~/.bash_logout

+

The individual login shell +cleanup file, executed when a login shell exits

-  -

SEE ALSO

+

~/.bash_history

+

The default value of +HISTFILE, the file in which bash saves the command +history

-
-
Bash Reference Manual, Brian Fox and Chet Ramey
-
The Gnu Readline Library, Brian Fox and Chet Ramey
-
The Gnu History Library, Brian Fox and Chet Ramey
-
Portable Operating System Interface (POSIX) Part 2: Shell and Utilities, IEEE -
-http://pubs.opengroup.org/onlinepubs/9799919799/ -
http://tiswww.case.edu/~chet/bash/POSIX - a description of posix mode
-
sh(1), ksh(1), csh(1)
-
emacs(1), vi(1)
-
readline(3)
+

~/.inputrc

-
-  -

FILES

+

Individual readline +initialization file

+

AUTHORS + +

-
-
-/bin/bash -
-The bash executable -
-/etc/profile +

Brian Fox, Free +Software Foundation
+bfox@gnu.org

-
-The systemwide initialization file, executed for login shells -
-~/.bash_profile +

Chet Ramey, Case +Western Reserve University
+chet.ramey@case.edu

-
-The personal initialization file, executed for login shells -
-~/.bashrc +

BUG REPORTS + +

-
-The individual per-interactive-shell startup file -
-~/.bash_logout -
-The individual login shell cleanup file, executed when a login shell exits -
-~/.bash_history +

If you find a +bug in 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 bash. The latest +version is always available from +ftp://ftp.gnu.org/pub/gnu/bash/ and +http://git.savannah.gnu.org/cgit/bash.git/snapshot/bash-master.tar.gz.

-
-The default value of HISTFILE, the file in which bash saves the -command history -
-~/.inputrc +

Once you have +determined that a bug actually exists, use the +bashbug command to submit a bug report. If you have a +fix, you are encouraged to mail that as well! You may send +suggestions and “philosophical” bug reports to +bug-bash@gnu.org or post them to the Usenet newsgroup +gnu.bash.bug.

-
-Individual readline initialization file +

ALL bug reports +should include:
+The version number of bash
+The hardware and operating system
+The compiler used to compile
+A description of the bug behavior
+A short script or “recipe” which exercises the +bug

-
-  -

AUTHORS

+

bashbug +inserts the first three items automatically into the +template it provides for filing a bug report.

-Brian Fox, Free Software Foundation -
+

Comments and bug +reports concerning this manual page should be directed to +chet.ramey@case.edu.

-bfox@gnu.org -

+

BUGS + +

-Chet Ramey, Case Western Reserve University -
-chet.ramey@case.edu -  -

BUG REPORTS

+

It’s too +big and too slow.

-If you find a bug in -bash, +

There are some +subtle differences between bash and traditional +versions of sh, mostly because of the +POSIX specification.

-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 -bash. +

Aliases are +confusing in some uses.

-The latest version is always available from -ftp://ftp.gnu.org/pub/gnu/bash/ and -http://git.savannah.gnu.org/cgit/bash.git/snapshot/bash-master.tar.gz. -

+

Shell builtin +commands and functions are not stoppable/restartable.

-Once you have determined that a bug actually exists, use the -bashbug +

Compound +commands and command lists of the form “a ; b ; +c” are not handled gracefully when combined with +process suspension. When a process is stopped, the shell +immediately executes the next command in the list or breaks +out of any existing loops. It suffices to enclose the +command in parentheses to force it into a subshell, which +may be stopped as a unit, or to start the command in the +background and immediately bring it into the foreground.

-command to submit a bug report. -If you have a fix, you are encouraged to mail that as well! -You may send suggestions and - -bug reports to bug-bash@gnu.org or post them to the Usenet -newsgroup -gnu.bash.bug. - -

- -ALL bug reports should include: -

- - -

-
The version number of bash
-
The hardware and operating system
-
The compiler used to compile
-
A description of the bug behavior
-
A short script or
- -which exercises the bug - -
-

- -bashbug - -inserts the first three items automatically into the template -it provides for filing a bug report. -

- -Comments and bug reports concerning -this manual page should be directed to -chet.ramey@case.edu. - -  -

BUGS

- -It's too big and too slow. -

- -There are some subtle differences between -bash - -and traditional versions of -sh, - -mostly because of the -POSIX -specification. -

- -Aliases are confusing in some uses. -

- -Shell builtin commands and functions are not stoppable/restartable. -

- -Compound commands and command lists of the form - -are not handled gracefully when combined with process suspension. -When a process is stopped, the shell immediately executes the next -command in the list or breaks out of any existing loops. -It suffices to enclose the command in parentheses to -force it into a subshell, which may be stopped as a unit, -or to start the command in the background and immediately -bring it into the foreground. -

- -Array variables may not (yet) be exported. - - - -

- - - -
GNU Bash 5.32025 August 25BASH(1) -
-
- 

Index

-
-
NAME
-
SYNOPSIS
-
COPYRIGHT
-
DESCRIPTION
-
OPTIONS
-
ARGUMENTS
-
INVOCATION
-
DEFINITIONS
-
RESERVED WORDS
-
SHELL GRAMMAR
-
-
Simple Commands
-
Pipelines
-
Lists
-
Compound Commands
-
Coprocesses
-
Shell Function Definitions
-
-
COMMENTS
-
QUOTING
-
-
Translating Strings
-
-
PARAMETERS
-
-
Positional Parameters
-
Special Parameters
-
Shell Variables
-
Arrays
-
-
EXPANSION
-
-
Brace Expansion
-
Tilde Expansion
-
Parameter Expansion
-
Command Substitution
-
Arithmetic Expansion
-
Process Substitution
-
Word Splitting
-
Pathname Expansion
-
Quote Removal
-
-
REDIRECTION
-
-
Redirecting Input
-
Redirecting Output
-
Appending Redirected Output
-
Redirecting Standard Output and Standard Error
-
Appending Standard Output and Standard Error
-
Here Documents
-
Here Strings
-
Duplicating File Descriptors
-
Moving File Descriptors
-
Opening File Descriptors for Reading and Writing
-
-
ALIASES
-
FUNCTIONS
-
ARITHMETIC EVALUATION
-
CONDITIONAL EXPRESSIONS
-
SIMPLE COMMAND EXPANSION
-
COMMAND EXECUTION
-
COMMAND EXECUTION ENVIRONMENT
-
ENVIRONMENT
-
EXIT STATUS
-
SIGNALS
-
JOB CONTROL
-
PROMPTING
-
READLINE
-
-
Readline Notation
-
Readline Initialization
-
Readline Key Bindings
-
Readline Variables
-
Readline Conditional Constructs
-
Searching
-
Readline Command Names
-
Commands for Moving
-
Commands for Manipulating the History
-
Commands for Changing Text
-
Killing and Yanking
-
Numeric Arguments
-
Completing
-
Keyboard Macros
-
Miscellaneous
-
Programmable Completion
-
-
HISTORY
-
HISTORY EXPANSION
-
-
Event Designators
-
Word Designators
-
Modifiers
-
-
SHELL BUILTIN COMMANDS
-
SHELL COMPATIBILITY MODE
-
RESTRICTED SHELL
-
SEE ALSO
-
FILES
-
AUTHORS
-
BUG REPORTS
-
BUGS
-
-
-This document was created by man2html from /usr/local/src/bash/bash-20250822/doc/bash.1.
-Time: 25 August 2025 11:45:48 EDT - - +

Array variables +may not (yet) be exported.

+
+ + diff --git a/doc/bash.info b/doc/bash.info index 6af1231ac..2ac5f2d2e 100644 --- a/doc/bash.info +++ b/doc/bash.info @@ -1,9 +1,9 @@ This is bash.info, produced by makeinfo version 7.2 from bashref.texi. This text is a brief description of the features that are present in the -Bash shell (version 5.3, 7 August 2025). +Bash shell (version 5.3, 6 September 2025). - This is Edition 5.3, last updated 7 August 2025, of ‘The GNU Bash + This is Edition 5.3, last updated 6 September 2025, of ‘The GNU Bash Reference Manual’, for ‘Bash’, Version 5.3. Copyright © 1988-2025 Free Software Foundation, Inc. @@ -26,10 +26,10 @@ Bash Features ************* This text is a brief description of the features that are present in the -Bash shell (version 5.3, 7 August 2025). The Bash home page is +Bash shell (version 5.3, 6 September 2025). The Bash home page is . - This is Edition 5.3, last updated 7 August 2025, of ‘The GNU Bash + This is Edition 5.3, last updated 6 September 2025, of ‘The GNU Bash Reference Manual’, for ‘Bash’, Version 5.3. Bash contains features that appear in other popular shells, and some @@ -259,9 +259,9 @@ Bash is an acronym for ‘Bourne-Again SHell’. The Bourne shell is the traditional Unix shell originally written by Stephen Bourne. All of the Bourne shell builtin commands are available in Bash, and the rules for evaluation and quoting are taken from the POSIX specification for the -'standard' Unix shell. +"standard" Unix shell. - This chapter briefly summarizes the shell's 'building blocks': + This chapter briefly summarizes the shell's "building blocks": commands, control structures, shell functions, shell parameters, shell expansions, redirections, which are a way to direct input and output from and to named files, and how the shell executes commands. @@ -642,18 +642,27 @@ File: bash.info, Node: Reserved Words, Next: Simple Commands, Up: Shell Comma Reserved words are words that have special meaning to the shell. They are used to begin and end the shell's compound commands. - The following words are recognized as reserved when unquoted and the -first word of a command (see below for exceptions): + Reserved words are recognized as reserved when unquoted and either + + • the first word of a command; + • the first word following a reserved word other than ‘case’, ‘for’, + ‘select’, or ‘in’; + • the third word of a ‘case’ command (only ‘in’ is valid); + • the third word of a ‘for’ or ‘select’ command (only ‘in’ and ‘do’ + are valid); + • following a control operator. + +The shell will also recognize reserved words where the syntax of a +command specifically requires the reserved word as the only correct +token. + + The following are reserved words: ‘if’ ‘then’ ‘elif’ ‘else’ ‘fi’ ‘time’ ‘for’ ‘in’ ‘until’ ‘while’ ‘do’ ‘done’ ‘case’ ‘esac’ ‘coproc’‘select’‘function’ ‘{’ ‘}’ ‘[[’ ‘]]’ ‘!’ -‘in’ is recognized as a reserved word if it is the third word of a -‘case’ or ‘select’ command. ‘in’ and ‘do’ are recognized as reserved -words if they are the third word in a ‘for’ command. -  File: bash.info, Node: Simple Commands, Next: Pipelines, Prev: Reserved Words, Up: Shell Commands @@ -740,40 +749,23 @@ File: bash.info, Node: Lists, Next: Compound Commands, Prev: Pipelines, Up: 3.2.4 Lists of Commands ----------------------- -A ‘list’ is a sequence of one or more pipelines separated by one of the -operators ‘;’, ‘&’, ‘&&’, or ‘||’, and optionally terminated by one of -‘;’, ‘&’, or a ‘newline’. - - Of these list operators, ‘&&’ and ‘||’ have equal precedence, -followed by ‘;’ and ‘&’, which have equal precedence. - - A sequence of one or more newlines may appear in a ‘list’ to delimit -commands, equivalent to a semicolon. - - If a command is terminated by the control operator ‘&’, the shell -executes the command asynchronously in a subshell. This is known as -executing the command in the “background”, and these are referred to as -“asynchronous” commands. The shell does not wait for the command to -finish, and the return status is 0 (true). When job control is not -active (*note Job Control::), the standard input for asynchronous -commands, in the absence of any explicit redirections, is redirected -from ‘/dev/null’. - - Commands separated by a ‘;’ are executed sequentially; the shell -waits for each command to terminate in turn. The return status is the -exit status of the last command executed. +A ‘list’ is a sequence of one or more AND or OR lists separated by one +of the operators ‘;’ or ‘&’, or a ‘newline’, and optionally terminated +by one of those three characters. AND and OR lists are sequences of one or more pipelines separated by the control operators ‘&&’ and ‘||’, respectively. AND and OR lists are executed with left associativity. An AND list has the form + COMMAND1 && COMMAND2 COMMAND2 is executed if, and only if, COMMAND1 returns an exit status of zero (success). An OR list has the form + COMMAND1 || COMMAND2 COMMAND2 is executed if, and only if, COMMAND1 returns a non-zero exit @@ -782,6 +774,28 @@ status. The return status of AND and OR lists is the exit status of the last command executed in the list. + Of these list operators, ‘&&’ and ‘||’ have equal precedence, +followed by ‘;’ and ‘&’, which have equal precedence. + + A sequence of one or more newlines may appear in a ‘list’ to delimit +commands, equivalent to a semicolon. + + If a command is terminated by the control operator ‘&’, the shell +executes the command asynchronously in a subshell. This is known as +executing the command in the “background”, and these are referred to as +“asynchronous” commands. The shell does not wait for the command to +finish, and the return status is 0 (true). When job control is not +active (*note Job Control::), the standard input for asynchronous +commands, in the absence of any explicit redirections, is redirected +from ‘/dev/null’. + + Commands separated or terminated by ‘;’ (or equivalent ‘newline’) are +executed sequentially; the shell waits for each command to terminate in +turn. + + The return status of a list is the exit status of the last command +executed. +  File: bash.info, Node: Compound Commands, Next: Coprocesses, Prev: Lists, Up: Shell Commands @@ -909,27 +923,25 @@ File: bash.info, Node: Conditional Constructs, Next: Command Grouping, Prev: ‘case’ will selectively execute the COMMAND-LIST corresponding to the first PATTERN that matches WORD, proceeding from the first pattern to the last. The match is performed according to the rules - described below in *note Pattern Matching::. If the ‘nocasematch’ + described below in *note Pattern Matching::. The WORD undergoes + tilde expansion, parameter expansion, command substitution, process + substitution, arithmetic expansion, and quote removal (*note Shell + Parameter Expansion::) before the shell attempts to match the + pattern. Each PATTERN examined undergoes tilde expansion, + parameter expansion, command substitution, arithmetic expansion, + process substitution, and quote removal. If the ‘nocasematch’ shell option (see the description of ‘shopt’ in *note The Shopt Builtin::) is enabled, the match is performed without regard to the - case of alphabetic characters. The ‘|’ is used to separate - multiple patterns in a pattern list, and the ‘)’ operator - terminates the pattern list. A pattern list and an associated - COMMAND-LIST is known as a CLAUSE. - - Each clause must be terminated with ‘;;’, ‘;&’, or ‘;;&’. The WORD - undergoes tilde expansion, parameter expansion, command - substitution, process substitution, arithmetic expansion, and quote - removal (*note Shell Parameter Expansion::) before the shell - attempts to match the pattern. Each PATTERN undergoes tilde - expansion, parameter expansion, command substitution, arithmetic - expansion, process substitution, and quote removal. + case of alphabetic characters. - There may be an arbitrary number of ‘case’ clauses, each terminated - by a ‘;;’, ‘;&’, or ‘;;&’. The first pattern that matches - determines the command-list that is executed. It's a common idiom - to use ‘*’ as the final pattern to define the default case, since - that pattern will always match. + A pattern list is a set of one or more patterns separated by ‘|’, + and terminated by the ‘)’ operator. A case CLAUSE is a pattern + list and an associated COMMAND-LIST, terminated by ‘;;’, ‘;&’, or + ‘;;&’. The terminator is optional for the last clause preceding + ‘esac’. There may be an arbitrary number of ‘case’ clauses. The + first pattern that matches determines the command-list that is + executed. It's a common idiom to use ‘*’ as the final pattern to + define the default case, since that pattern will always match. Here is an example using ‘case’ in a script that could be used to describe one interesting feature of an animal: @@ -944,13 +956,15 @@ File: bash.info, Node: Conditional Constructs, Next: Command Grouping, Prev: esac echo " legs." - If the ‘;;’ operator is used, the ‘case’ command completes after - the first pattern match. Using ‘;&’ in place of ‘;;’ causes - execution to continue with the COMMAND-LIST associated with the - next clause, if any. Using ‘;;&’ in place of ‘;;’ causes the shell - to test the patterns in the next clause, if any, and execute any - associated COMMAND-LIST if the match succeeds, continuing the case - statement execution as if the pattern list had not matched. + When a match is found, ‘case’ executes the corresponding + COMMAND-LIST. If the ‘;;’ operator terminates the case clause, the + ‘case’ command completes after the first pattern match. Using the + ‘;&’ terminator continues execution with the COMMAND-LIST + associated with the next clause, if any. Using the ‘;;&’ + terminator causes the shell to test the pattern list in the next + clause, if any, and execute any associated COMMAND-LIST if the + match succeeds, continuing the case statement execution as if the + pattern list had not matched. The return status is zero if no PATTERN matches. Otherwise, the return status is the exit status of the last COMMAND-LIST executed. @@ -2890,12 +2904,12 @@ characters ‘\’, ‘$’, and ‘`’; however, double quote characters have special meaning. If the redirection operator is ‘<<-’, the shell strips leading tab -characters are stripped from input lines and the line containing -DELIMITER. This allows here-documents within shell scripts to be -indented in a natural fashion. +characters from input lines and the line containing DELIMITER. This +allows here-documents within shell scripts to be indented in a natural +fashion. - If the delimiter is not quoted, the ‘\’ sequence is treated -as a line continuation: the two lines are joined and the + If the delimiter is not quoted, the shell treats the ‘\’ +sequence as a line continuation: the two lines are joined and the backslash-newline is removed. This happens while reading the here-document, before the check for the ending delimiter, so joined lines can form the end delimiter. @@ -7770,10 +7784,10 @@ startup files. result from a ‘$PATH’ search. 22. The message printed by the job control code and builtins when a - job exits with a non-zero status is 'Done(status)'. + job exits with a non-zero status is "Done(status)". 23. The message printed by the job control code and builtins when a - job is stopped is 'Stopped(SIGNAME)', where SIGNAME is, for + job is stopped is "Stopped(SIGNAME)", where SIGNAME is, for example, ‘SIGTSTP’. 24. If the shell is interactive, Bash does not perform job @@ -8527,10 +8541,10 @@ File: bash.info, Node: Introduction and Notation, Next: Readline Interaction, The following paragraphs use Emacs style to describe the notation used to represent keystrokes. - The text ‘C-k’ is read as 'Control-K' and describes the character + The text ‘C-k’ is read as "Control-K" and describes the character produced when the key is pressed while the Control key is depressed. - The text ‘M-k’ is read as 'Meta-K' and describes the character + The text ‘M-k’ is read as "Meta-K" and describes the character produced when the Meta key (if you have one) is depressed, and the key is pressed (a “meta character”), then both are released. The Meta key is labeled or