4 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
9 bash, :, ., alias, bg, bind, break, builtin, bye, case, cd,
10 command, continue, declare, dirs, echo, enable, eval, exec,
11 exit, export, fc, fg, for, getopts, hash, help, history, if,
12 jobs, kill, let, local, logout, popd, pushd, pwd, read,
13 readonly, return, set, shift, source, suspend, test, times,
14 trap, type, typeset, ulimit, umask, unalias, unset, until,
15 wait, while - bash built-in commands, see bash(1)
18 : [_
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs]
19 No effect; the command does nothing beyond expanding
20 _
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs and performing any specified redirections. A
21 zero exit code is returned.
23 . _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be [_
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs]
24 source _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be [_
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs]
25 Read and execute commands from _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be in the current
26 shell environment and return the exit status of the
27 last command executed from _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be. If _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be does
28 not contain a slash, pathnames in PATH are used to find
29 the directory containing _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be. The file searched
30 for in PATH need not be executable. The current direc-
31 tory is searched if no file is found in PATH. If any
32 _
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs are supplied, they become the positional
33 parameters when _
\bf_
\bi_
\bl_
\be is executed. Otherwise the posi-
34 tional parameters are unchanged. The return status is
35 the status of the last command exited within the script
36 (0 if no commands are executed), and false if _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be
39 alias [_
\bn_
\ba_
\bm_
\be[=_
\bv_
\ba_
\bl_
\bu_
\be] ...]
40 Alias with no arguments prints the list of aliases in
41 the form _
\bn_
\ba_
\bm_
\be=_
\bv_
\ba_
\bl_
\bu_
\be on standard output. When arguments
42 are supplied, an alias is defined for each _
\bn_
\ba_
\bm_
\be whose
43 _
\bv_
\ba_
\bl_
\bu_
\be is given. A trailing space in _
\bv_
\ba_
\bl_
\bu_
\be causes the
44 next word to be checked for alias substitution when the
45 alias is expanded. For each _
\bn_
\ba_
\bm_
\be in the argument list
46 for which no _
\bv_
\ba_
\bl_
\bu_
\be is supplied, the name and value of
47 the alias is printed. Alias returns true unless a _
\bn_
\ba_
\bm_
\be
48 is given for which no alias has been defined.
50 bg [_
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc]
51 Place _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc in the background, as if it had been
52 started with &. If _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc is not present, the shell's
53 notion of the _
\bc_
\bu_
\br_
\br_
\be_
\bn_
\bt _
\bj_
\bo_
\bb is used. bg _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc returns
54 0 unless run when job control is disabled or, when run
55 with job control enabled, if _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc was not found or
56 started without job control.
58 bind [-m _
\bk_
\be_
\by_
\bm_
\ba_
\bp] [-lvd] [-q _
\bn_
\ba_
\bm_
\be]
59 bind [-m _
\bk_
\be_
\by_
\bm_
\ba_
\bp] -f _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be
63 GNU Last change: 1993 September 16 1
70 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
74 bind [-m _
\bk_
\be_
\by_
\bm_
\ba_
\bp] _
\bk_
\be_
\by_
\bs_
\be_
\bq:_
\bf_
\bu_
\bn_
\bc_
\bt_
\bi_
\bo_
\bn-_
\bn_
\ba_
\bm_
\be
75 Display current readline key and function bindings, or
76 bind a key sequence to a readline function or macro.
77 The binding syntax accepted is identical to that of
78 ._
\bi_
\bn_
\bp_
\bu_
\bt_
\br_
\bc, but each binding must be passed as a separate
79 argument; e.g., '"\C-x\C-r": re-read-init-file'.
80 Options, if supplied, have the following meanings:
81 -m _
\bk_
\be_
\by_
\bm_
\ba_
\bp
82 Use _
\bk_
\be_
\by_
\bm_
\ba_
\bp as the keymap to be affected by the
83 subsequent bindings. Acceptable _
\bk_
\be_
\by_
\bm_
\ba_
\bp names are
84 _
\be_
\bm_
\ba_
\bc_
\bs, _
\be_
\bm_
\ba_
\bc_
\bs-_
\bs_
\bt_
\ba_
\bn_
\bd_
\ba_
\br_
\bd, _
\be_
\bm_
\ba_
\bc_
\bs-_
\bm_
\be_
\bt_
\ba, _
\be_
\bm_
\ba_
\bc_
\bs-_
\bc_
\bt_
\bl_
\bx, _
\bv_
\bi,
85 _
\bv_
\bi-_
\bm_
\bo_
\bv_
\be, _
\bv_
\bi-_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd, and _
\bv_
\bi-_
\bi_
\bn_
\bs_
\be_
\br_
\bt. _
\bv_
\bi is
86 equivalent to _
\bv_
\bi-_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd; _
\be_
\bm_
\ba_
\bc_
\bs is equivalent to
87 _
\be_
\bm_
\ba_
\bc_
\bs-_
\bs_
\bt_
\ba_
\bn_
\bd_
\ba_
\br_
\bd.
88 -l List the names of all readline functions
89 -v List current function names and bindings
90 -d Dump function names and bindings in such a way
91 that they can be re-read
92 -f _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be
93 Read key bindings from _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be
94 -q _
\bf_
\bu_
\bn_
\bc_
\bt_
\bi_
\bo_
\bn
95 Query about which keys invoke the named _
\bf_
\bu_
\bn_
\bc_
\bt_
\bi_
\bo_
\bn
97 The return value is 0 unless an unrecognized option is
98 given or an error occurred.
101 Exit from within a for, while, or until loop. If _
\bn is
102 specified, break _
\bn levels. _
\bn must be >
\b_ 1. If _
\bn is
103 greater than the number of enclosing loops, all enclos-
104 ing loops are exited. The return value is 0 unless the
105 shell is not executing a loop when break is executed.
107 builtin _
\bs_
\bh_
\be_
\bl_
\bl-_
\bb_
\bu_
\bi_
\bl_
\bt_
\bi_
\bn [_
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs]
108 Execute the specified shell builtin, passing it _
\ba_
\br_
\bg_
\bu_
\b-
109 _
\bm_
\be_
\bn_
\bt_
\bs, and return its exit status. This is useful when
110 you wish to define a function whose name is the same as
111 a shell builtin, but need the functionality of the
112 builtin within the function itself. The cd builtin is
113 commonly redefined this way. The return status is
114 false if _
\bs_
\bh_
\be_
\bl_
\bl-_
\bb_
\bu_
\bi_
\bl_
\bt_
\bi_
\bn is not a shell builtin command.
117 Change the current directory to _
\bd_
\bi_
\br. The variable HOME
118 is the default _
\bd_
\bi_
\br. The variable CDPATH defines the
119 search path for the directory containing _
\bd_
\bi_
\br. Alterna-
120 tive directory names are separated by a colon (:). A
121 null directory name in CDPATH is the same as the
122 current directory, i.e., ``.''. If _
\bd_
\bi_
\br begins with a
123 slash (/), then CDPATH is not used. An argument of -
124 is equivalent to $OLDPWD. The return value is true if
125 the directory was successfully changed; false
129 GNU Last change: 1993 September 16 2
136 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
142 command [-pVv] _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd [_
\ba_
\br_
\bg ...]
143 Run _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd with _
\ba_
\br_
\bg_
\bs suppressing the normal shell
144 function lookup. Only builtin commands or commands
145 found in the PATH are executed. If the -p option is
146 given, the search for _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is performed using a
147 default value for PATH that is guaranteed to find all
148 of the standard utilities. If either the -V or -v
149 option is supplied, a description of _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is
150 printed. The -v option causes a single word indicating
151 the command or pathname used to invoke _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd to be
152 printed; the -V option produces a more verbose descrip-
153 tion. An argument of -- disables option checking for
154 the rest of the arguments. If the -V or -v option is
155 supplied, the exit status is 0 if _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd was found,
156 and 1 if not. If neither option is supplied and an
157 error occurred or _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd cannot be found, the exit
158 status is 127. Otherwise, the exit status of the com-
159 mand builtin is the exit status of _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd.
162 Resume the next iteration of the enclosing for, while,
163 or until loop. If _
\bn is specified, resume at the _
\bnth
164 enclosing loop. _
\bn must be >
\b_ 1. If _
\bn is greater than
165 the number of enclosing loops, the last enclosing loop
166 (the `top-level' loop) is resumed. The return value is
167 0 unless the shell is not executing a loop when con-
170 declare [-frxi] [_
\bn_
\ba_
\bm_
\be[=_
\bv_
\ba_
\bl_
\bu_
\be]]
171 typeset [-frxi] [_
\bn_
\ba_
\bm_
\be[=_
\bv_
\ba_
\bl_
\bu_
\be]]
172 Declare variables and/or give them attributes. If no
173 _
\bn_
\ba_
\bm_
\bes are given, then display the values of variables
174 instead. The options can be used to restrict output to
175 variables with the specified attribute.
176 -f Use function names only
177 -r Make _
\bn_
\ba_
\bm_
\bes readonly. These names cannot then be
178 assigned values by subsequent assignment state-
180 -x Mark _
\bn_
\ba_
\bm_
\bes for export to subsequent commands via
182 -i The variable is treated as an integer; arithmetic
183 evaluation (see ARITHMETIC EVALUATION ) is per-
184 formed when the variable is assigned a value.
186 Using `+' instead of `-' turns off the attribute
187 instead. When used in a function, makes _
\bn_
\ba_
\bm_
\bes local,
188 as with the local command. The return value is 0
189 unless an illegal option is encountered, an attempt is
190 made to define a function using "-f foo=bar", one of
191 the _
\bn_
\ba_
\bm_
\be_
\bs is not a legal shell variable name, an
195 GNU Last change: 1993 September 16 3
202 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
206 attempt is made to turn off readonly status for a
207 readonly variable, or an attempt is made to display a
208 non-existant function with -f.
211 Display the list of currently remembered directories.
212 Directories are added to the list with the pushd com-
213 mand; the popd command moves back up through the list.
214 +n displays the _
\bnth entry counting from the left of
215 the list shown by dirs when invoked without
216 options, starting with zero.
217 -n displays the _
\bnth entry counting from the right of
218 the list shown by dirs when invoked without
219 options, starting with zero.
220 -l produces a longer listing; the default listing
221 format uses a tilde to denote the home directory.
223 The return value is 0 unless an illegal option is sup-
224 plied or _
\bn indexes beyond the end of the directory
227 echo [-neE] [_
\ba_
\br_
\bg ...]
228 Output the _
\ba_
\br_
\bgs, separated by spaces. The return
229 status is always 0. If -n is specified, the trailing
230 newline is suppressed. If the -e option is given,
231 interpretation of the following backslash-escaped char-
232 acters is enabled. The -E option disables the
233 interpretation of these escape characters, even on sys-
234 tems where they are interpreted by default.
237 \c suppress trailing newline
244 \nnn the character whose ASCII code is _
\bn_
\bn_
\bn (octal)
246 enable [-n] [-all] [_
\bn_
\ba_
\bm_
\be ...]
247 Enable and disable builtin shell commands. This allows
248 the execution of a disk command which has the same name
249 as a shell builtin without specifying a full pathname.
250 If -n is used, each _
\bn_
\ba_
\bm_
\be is disabled; otherwise, _
\bn_
\ba_
\bm_
\be_
\bs
251 are enabled. For example, to use the test binary found
252 via the PATH instead of the shell builtin version, type
253 ``enable -n test''. If no arguments are given, a list
254 of all enabled shell builtins is printed. If only -n
255 is supplied, a list of all disabled builtins is
256 printed. If only -all is supplied, the list printed
257 includes all builtins, with an indication of whether or
261 GNU Last change: 1993 September 16 4
268 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
272 not each is enabled. enable accepts -a as a synonym
273 for -all. The return value is 0 unless a _
\bn_
\ba_
\bm_
\be is not a
276 eval [_
\ba_
\br_
\bg ...]
277 The _
\ba_
\br_
\bgs are read and concatenated together into a sin-
278 gle command. This command is then read and executed by
279 the shell, and its exit status is returned as the value
280 of the eval command. If there are no _
\ba_
\br_
\bg_
\bs, or only
281 null arguments, eval returns true.
283 exec [[-] _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd [_
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs]]
284 If _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is specified, it replaces the shell. No new
285 process is created. The _
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs become the arguments
286 to _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd. If the first argument is -, the shell
287 places a dash in the zeroth arg passed to _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd.
288 This is what login does. If the file cannot be exe-
289 cuted for some reason, a non-interactive shell exits,
290 unless the shell variable no_exit_on_failed_exec
291 exists, in which case it returns failure. An interac-
292 tive shell returns failure if the file cannot be exe-
293 cuted. If _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is not specified, any redirections
294 take effect in the current shell, and the return status
298 Cause the shell to exit with a status of _
\bn. If _
\bn is
299 omitted, the exit status is that of the last command
300 executed. A trap on EXIT is executed before the shell
303 export [-nf] [_
\bn_
\ba_
\bm_
\be[=_
\bw_
\bo_
\br_
\bd]] ...
305 The supplied _
\bn_
\ba_
\bm_
\be_
\bs are marked for automatic export to
306 the environment of subsequently executed commands. If
307 the -f option is given, the _
\bn_
\ba_
\bm_
\be_
\bs refer to functions.
308 If no _
\bn_
\ba_
\bm_
\be_
\bs are given, or if the -p option is supplied,
309 a list of all names that are exported in this shell is
310 printed. The -n option causes the export property to
311 be removed from the named variables. An argument of --
312 disables option checking for the rest of the arguments.
313 export returns an exit status of 0 unless an illegal
314 option is encountered, one of the _
\bn_
\ba_
\bm_
\be_
\bs is not a legal
315 shell variable name, or -f is supplied with a _
\bn_
\ba_
\bm_
\be that
318 fc [-e _
\be_
\bn_
\ba_
\bm_
\be] [-nlr] [_
\bf_
\bi_
\br_
\bs_
\bt] [_
\bl_
\ba_
\bs_
\bt]
319 fc -s [_
\bp_
\ba_
\bt=_
\br_
\be_
\bp] [_
\bc_
\bm_
\bd]
320 Fix Command. In the first form, a range of commands
321 from _
\bf_
\bi_
\br_
\bs_
\bt to _
\bl_
\ba_
\bs_
\bt is selected from the history list.
322 _
\bF_
\bi_
\br_
\bs_
\bt and _
\bl_
\ba_
\bs_
\bt may be specified as a string (to locate
323 the last command beginning with that string) or as a
327 GNU Last change: 1993 September 16 5
334 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
338 number (an index into the history list, where a nega-
339 tive number is used as an offset from the current com-
340 mand number). If _
\bl_
\ba_
\bs_
\bt is not specified it is set to
341 the current command for listing (so that fc -l -10
342 prints the last 10 commands) and to _
\bf_
\bi_
\br_
\bs_
\bt otherwise.
343 If _
\bf_
\bi_
\br_
\bs_
\bt is not specified it is set to the previous
344 command for editing and -16 for listing.
346 The -n flag suppresses the command numbers when list-
347 ing. The -r flag reverses the order of the commands.
348 If the -l flag is given, the commands are listed on
349 standard output. Otherwise, the editor given by _
\be_
\bn_
\ba_
\bm_
\be
350 is invoked on a file containing those commands. If
351 _
\be_
\bn_
\ba_
\bm_
\be is not given, the value of the FCEDIT variable is
352 used, and the value of EDITOR if FCEDIT is not set. If
353 neither variable is set, is used. When editing is com-
354 plete, the edited commands are echoed and executed.
356 In the second form, _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is re-executed after each
357 instance of _
\bp_
\ba_
\bt is replaced by _
\br_
\be_
\bp. A useful alias to
358 use with this is ``r=fc -s'', so that typing ``r cc''
359 runs the last command beginning with ``cc'' and typing
360 ``r'' re-executes the last command.
362 If the first form is used, the return value is 0 unless
363 an illegal option is encountered or _
\bf_
\bi_
\br_
\bs_
\bt or _
\bl_
\ba_
\bs_
\bt
364 specify history lines out of range. If the -e option
365 is supplied, the return value is the value of the last
366 command executed or failure if an error occurs with the
367 temporary file of commands. If the second form is
368 used, the return status is that of the command re-
369 executed, unless _
\bc_
\bm_
\bd does not specify a valid history
370 line, in which case fc returns failure.
372 fg [_
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc]
373 Place _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc in the foreground, and make it the
374 current job. If _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc is not present, the shell's
375 notion of the _
\bc_
\bu_
\br_
\br_
\be_
\bn_
\bt _
\bj_
\bo_
\bb is used. The return value is
376 that of the command placed into the foreground, or
377 failure if run when job control is disabled or, when
378 run with job control enabled, if _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc does not
379 specify a valid job or _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc specifies a job that was
380 started without job control.
382 getopts _
\bo_
\bp_
\bt_
\bs_
\bt_
\br_
\bi_
\bn_
\bg _
\bn_
\ba_
\bm_
\be [_
\ba_
\br_
\bg_
\bs]
383 getopts is used by shell procedures to parse positional
384 parameters. _
\bo_
\bp_
\bt_
\bs_
\bt_
\br_
\bi_
\bn_
\bg contains the option letters to
385 be recognized; if a letter is followed by a colon, the
386 option is expected to have an argument, which should be
387 separated from it by white space. Each time it is
388 invoked, getopts places the next option in the shell
389 variable _
\bn_
\ba_
\bm_
\be, initializing _
\bn_
\ba_
\bm_
\be if it does not exist,
393 GNU Last change: 1993 September 16 6
400 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
404 and the index of the next argument to be processed into
405 the variable OPTIND. OPTIND is initialized to 1 each
406 time the shell or a shell script is invoked. When an
407 option requires an argument, getopts places that argu-
408 ment into the variable OPTARG. The shell does not
409 reset OPTIND automatically; it must be manually reset
410 between multiple calls to getopts within the same shell
411 invocation if a new set of parameters is to be used.
413 getopts can report errors in two ways. If the first
414 character of _
\bo_
\bp_
\bt_
\bs_
\bt_
\br_
\bi_
\bn_
\bg is a colon, _
\bs_
\bi_
\bl_
\be_
\bn_
\bt error report-
415 ing is used. In normal operation diagnostic messages
416 are printed when illegal options or missing option
417 arguments are encountered. If the variable OPTERR is
418 set to 0, no error message will be displayed, even if
419 the first character of _
\bo_
\bp_
\bt_
\bs_
\bt_
\br_
\bi_
\bn_
\bg is not a colon.
421 If an illegal option is seen, getopts places ? into
422 _
\bn_
\ba_
\bm_
\be and, if not silent, prints an error message and
423 unsets OPTARG. If getopts is silent, the option char-
424 acter found is placed in OPTARG and no diagnostic mes-
427 If a required argument is not found, and getopts is not
428 silent, a question mark (?) is placed in _
\bn_
\ba_
\bm_
\be, OPTARG
429 is unset, and a diagnostic message is printed. If
430 getopts is silent, then a colon (:) is placed in _
\bn_
\ba_
\bm_
\be
431 and OPTARG is set to the option character found.
433 getopts normally parses the positional parameters, but
434 if more arguments are given in _
\ba_
\br_
\bg_
\bs, getopts parses
435 those instead. getopts returns true if an option,
436 specified or unspecified, is found. It returns false
437 if the end of options is encountered or an error
440 hash [-r] [_
\bn_
\ba_
\bm_
\be]
441 For each _
\bn_
\ba_
\bm_
\be, the full pathname of the command is
442 determined and remembered. The -r option causes the
443 shell to forget all remembered locations. If no argu-
444 ments are given, information about remembered commands
445 is printed. An argument of -- disables option checking
446 for the rest of the arguments. The return status is
447 true unless a _
\bn_
\ba_
\bm_
\be is not found or an illegal option is
450 help [_
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn]
451 Display helpful information about builtin commands. If
452 _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn is specified, help gives detailed help on all
453 commands matching _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn; otherwise a list of the
454 builtins is printed. The return status is 0 unless no
455 command matches _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn.
459 GNU Last change: 1993 September 16 7
466 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
471 history -rwan [_
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be]
472 With no options, display the command history list with
473 line numbers. Lines listed with a * have been modi-
474 fied. An argument of _
\bn lists only the last _
\bn lines.
475 If a non-option argument is supplied, it is used as the
476 name of the history file; if not, the value of HISTFILE
477 is used. Options, if supplied, have the following
479 -a Append the ``new'' history lines (history lines
480 entered since the beginning of the current bash
481 session) to the history file
482 -n Read the history lines not already read from the
483 history file into the current history list. These
484 are lines appended to the history file since the
485 beginning of the current bash session.
486 -r Read the contents of the history file and use them
487 as the current history
488 -w Write the current history to the history file,
489 overwriting the history file's contents.
491 The return value is 0 unless an illegal option is
492 encountered or an error occurs while reading or writing
495 jobs [-lnp] [ _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc ... ]
496 jobs -x _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd [ _
\ba_
\br_
\bg_
\bs ... ]
497 The first form lists the active jobs. The -l option
498 lists process IDs in addition to the normal informa-
499 tion; the -p option lists only the process ID of the
500 job's process group leader. The -n option displays
501 only jobs that have changed status since last notified.
502 If _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc is given, output is restricted to informa-
503 tion about that job. The return status is 0 unless an
504 illegal option is encountered or an illegal _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc is
507 If the -x option is supplied, jobs replaces any _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc
508 found in _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd or _
\ba_
\br_
\bg_
\bs with the corresponding process
509 group ID, and executes _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd passing it _
\ba_
\br_
\bg_
\bs, return-
512 kill [-s sigspec | -sigspec] [_
\bp_
\bi_
\bd | _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc] ...
513 kill -l [_
\bs_
\bi_
\bg_
\bn_
\bu_
\bm]
514 Send the signal named by _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc to the processes named
515 by _
\bp_
\bi_
\bd or _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc. _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc is either a signal name
516 such as SIGKILL or a signal number. If _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc is a
517 signal name, the name is case insensitive and may be
518 given with or without the SIG prefix. If _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc is
519 not present, then SIGTERM is assumed. An argument of
520 -l lists the signal names. If any arguments are sup-
521 plied when -l is given, the names of the specified
525 GNU Last change: 1993 September 16 8
532 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
536 signals are listed, and the return status is 0. An
537 argument of -- disables option checking for the rest of
538 the arguments. kill returns true if at least one sig-
539 nal was successfully sent, or false if an error occurs
540 or an illegal option is encountered.
542 let _
\ba_
\br_
\bg [_
\ba_
\br_
\bg ...]
543 Each _
\ba_
\br_
\bg is an arithmetic expression to be evaluated
544 (see ARITHMETIC EVALUATION). If the last _
\ba_
\br_
\bg evaluates
545 to 0, let returns 1; 0 is returned otherwise.
547 local [_
\bn_
\ba_
\bm_
\be[=_
\bv_
\ba_
\bl_
\bu_
\be] ...]
548 For each argument, create a local variable named _
\bn_
\ba_
\bm_
\be,
549 and assign it _
\bv_
\ba_
\bl_
\bu_
\be. When local is used within a func-
550 tion, it causes the variable _
\bn_
\ba_
\bm_
\be to have a visible
551 scope restricted to that function and its children.
552 With no operands, local writes a list of local vari-
553 ables to the standard output. It is an error to use
554 local when not within a function. The return status is
555 0 unless local is used outside a function, or an ille-
556 gal _
\bn_
\ba_
\bm_
\be is supplied.
562 Removes entries from the directory stack. With no
563 arguments, removes the top directory from the stack,
564 and performs a cd to the new top directory.
565 +n removes the _
\bnth entry counting from the left of
566 the list shown by dirs, starting with zero. For
567 example: ``popd +0'' removes the first directory,
568 ``popd +1'' the second.
569 -n removes the _
\bnth entry counting from the right of
570 the list shown by dirs, starting with zero. For
571 example: ``popd -0'' removes the last directory,
572 ``popd -1'' the next to last.
574 If the popd command is successful, a dirs is performed
575 as well, and the return status is 0. popd returns
576 false if an illegal option is encountered, the direc-
577 tory stack is empty, a non-existent directory stack
578 entry is specified, or the directory change fails.
582 Adds a directory to the top of the directory stack, or
583 rotates the stack, making the new top of the stack the
584 current working directory. With no arguments,
585 exchanges the top two directories and returns 0, unless
586 the directory stack is empty.
587 +n Rotates the stack so that the _
\bnth directory
591 GNU Last change: 1993 September 16 9
598 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
602 (counting from the left of the list shown by dirs)
604 -n Rotates the stack so that the _
\bnth directory
605 (counting from the right) is at the top.
606 dir adds _
\bd_
\bi_
\br to the directory stack at the top, making
607 it the new current working directory.
609 If the pushd command is successful, a dirs is performed
610 as well. If the first form is used, pushd returns 0
611 unless the cd to _
\bd_
\bi_
\br fails. With the second form,
612 pushd returns 0 unless the directory stack is empty, a
613 non-existant directory stack element is specified, or
614 the directory change to the specified new current
617 pwd Print the absolute pathname of the current working
618 directory. The path printed contains no symbolic links
619 if the -P option to the set builtin command is set.
620 See also the description of nolinks under Shell Vari-
621 ables above). The return status is 0 unless an error
622 occurs while reading the pathname of the current direc-
625 read [-r] [_
\bn_
\ba_
\bm_
\be ...]
626 One line is read from the standard input, and the first
627 word is assigned to the first _
\bn_
\ba_
\bm_
\be, the second word to
628 the second _
\bn_
\ba_
\bm_
\be, and so on, with leftover words
629 assigned to the last _
\bn_
\ba_
\bm_
\be. Only the characters in IFS
630 are recognized as word delimiters. If no _
\bn_
\ba_
\bm_
\be_
\bs are
631 supplied, the line read is assigned to the variable
632 REPLY. The return code is zero, unless end-of-file is
633 encountered. If the -r option is given, a backslash-
634 newline pair is not ignored, and the backslash is con-
635 sidered to be part of the line.
637 readonly [-f] [_
\bn_
\ba_
\bm_
\be ...]
639 The given _
\bn_
\ba_
\bm_
\be_
\bs are marked readonly and the values of
640 these _
\bn_
\ba_
\bm_
\be_
\bs may not be changed by subsequent assign-
641 ment. If the -f option is supplied, the functions
642 corresponding to the _
\bn_
\ba_
\bm_
\be_
\bs are so marked. If no argu-
643 ments are given, or if the -p option is supplied, a
644 list of all readonly names is printed. An argument of
645 -- disables option checking for the rest of the argu-
646 ments. The return status is 0 unless an illegal option
647 is encountered, one of the _
\bn_
\ba_
\bm_
\be_
\bs is not a legal shell
648 variable name, or -f is supplied with a _
\bn_
\ba_
\bm_
\be that is
652 Causes a function to exit with the return value speci-
653 fied by _
\bn. If _
\bn is omitted, the return status is that
657 GNU Last change: 1993 September 16 10
664 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
668 of the last command executed in the function body. If
669 used outside a function, but during execution of a
670 script by the . (source) command, it causes the shell
671 to stop executing that script and return either _
\bn or
672 the exit status of the last command executed within the
673 script as the exit status of the script. If used out-
674 side a function and not during execution of a script by
675 ., the return status is false.
677 set [--abefhkmnptuvxldCHP] [-o _
\bo_
\bp_
\bt_
\bi_
\bo_
\bn] [_
\ba_
\br_
\bg ...]
678 -a Automatically mark variables which are modified
679 or created for export to the environment of
681 -b Cause the status of terminated background jobs
682 to be reported immediately, rather than before
683 the next primary prompt. (Also see notify
684 under Shell Variables above).
685 -e Exit immediately if a _
\bs_
\bi_
\bm_
\bp_
\bl_
\be-_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd (see SHELL
686 GRAMMAR above) exits with a non-zero status.
687 The shell does not exit if the command that
688 fails is part of an _
\bu_
\bn_
\bt_
\bi_
\bl or _
\bw_
\bh_
\bi_
\bl_
\be loop, part
689 of an _
\bi_
\bf statement, part of a && or || list, or
690 if the command's return value is being inverted
692 -f Disable pathname expansion.
693 -h Locate and remember function commands as func-
694 tions are defined. Function commands are nor-
695 mally looked up when the function is executed.
696 -k All keyword arguments are placed in the
697 environment for a command, not just those that
698 precede the command name.
699 -m Monitor mode. Job control is enabled. This
700 flag is on by default for interactive shells on
701 systems that support it (see JOB CONTROL
702 above). Background processes run in a separate
703 process group and a line containing their exit
704 status is printed upon their completion.
705 -n Read commands but do not execute them. This
706 may be used to check a shell script for syntax
707 errors. This is ignored for interactive
709 -o _
\bo_
\bp_
\bt_
\bi_
\bo_
\bn-_
\bn_
\ba_
\bm_
\be
710 The _
\bo_
\bp_
\bt_
\bi_
\bo_
\bn-_
\bn_
\ba_
\bm_
\be can be one of the following:
714 The shell performs brace expansion (see
715 Brace Expansion above). This is on by
717 emacs Use an emacs-style command line editing
718 interface. This is enabled by default
719 when the shell is interactive, unless
723 GNU Last change: 1993 September 16 11
730 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
734 the shell is started with the -nol-
740 The effect is as if the shell command
741 `IGNOREEOF=10' had been executed (see
742 Shell Variables above).
744 Allow a word beginning with # to cause
745 that word and all remaining characters
746 on that line to be ignored in an
747 interactive shell (see COMMENTS above).
758 posix Change the behavior of bash where the
759 default operation differs from the
760 Posix 1003.2 standard to match the
765 vi Use a vi-style command line editing
768 If no _
\bo_
\bp_
\bt_
\bi_
\bo_
\bn-_
\bn_
\ba_
\bm_
\be is supplied, the values of
769 the current options are printed.
770 -p Turn on _
\bp_
\br_
\bi_
\bv_
\bi_
\bl_
\be_
\bg_
\be_
\bd mode. In this mode, the
771 $ENV file is not processed, and shell functions
772 are not inherited from the environment. This
773 is enabled automatically on startup if the
774 effective user (group) id is not equal to the
775 real user (group) id. Turning this option off
776 causes the effective user and group ids to be
777 set to the real user and group ids.
778 -t Exit after reading and executing one command.
779 -u Treat unset variables as an error when perform-
780 ing parameter expansion. If expansion is
781 attempted on an unset variable, the shell
782 prints an error message, and, if not interac-
783 tive, exits with a non-zero status.
784 -v Print shell input lines as they are read.
785 -x After expanding each _
\bs_
\bi_
\bm_
\bp_
\bl_
\be-_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd, bash
789 GNU Last change: 1993 September 16 12
796 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
800 displays the expanded value of PS4, followed by
801 the command and its expanded arguments.
802 -l Save and restore the binding of _
\bn_
\ba_
\bm_
\be in a for
803 _
\bn_
\ba_
\bm_
\be [in word] command (see SHELL GRAMMAR
805 -d Disable the hashing of commands that are looked
806 up for execution. Normally, commands are
807 remembered in a hash table, and once found, do
808 not have to be looked up again.
809 -C The effect is as if the shell command
810 `noclobber=' had been executed (see Shell Vari-
812 -H Enable ! style history substitution. This flag
813 is on by default when the shell is interactive.
814 -P If set, do not follow symbolic links when per-
815 forming commands such as cd which change the
816 current directory. The physical directory is
818 -- If no arguments follow this flag, then the
819 positional parameters are unset. Otherwise,
820 the positional parameters are set to the _
\ba_
\br_
\bgs,
821 even if some of them begin with a -.
822 - Signal the end of options, cause all remaining
823 _
\ba_
\br_
\bgs to be assigned to the positional parame-
824 ters. The -x and -v options are turned off.
825 If there are no _
\ba_
\br_
\bgs, the positional parameters
828 The flags are off by default unless otherwise noted.
829 Using + rather than - causes these flags to be turned
830 off. The flags can also be specified as options to an
831 invocation of the shell. The current set of flags may
832 be found in $-. After the option arguments are pro-
833 cessed, the remaining _
\bn _
\ba_
\br_
\bgs are treated as values for
834 the positional parameters and are assigned, in order,
835 to $1, $2, ... $_
\bn. If no options or _
\ba_
\br_
\bgs are supplied,
836 all shell variables are printed. The return status is
837 always true unless an illegal option is encountered.
840 The positional parameters from _
\bn+1 ... are renamed to
841 $1 .... Parameters represented by the numbers $# down
842 to $#-_
\bn+1 are unset. If _
\bn is 0, no parameters are
843 changed. If _
\bn is not given, it is assumed to be 1. _
\bn
844 must be a non-negative number less than or equal to $#.
845 If _
\bn is greater than $#, the positional parameters are
846 not changed. The return status is greater than 0 if _
\bn
847 is greater than $# or less than 0; otherwise 0.
850 Suspend the execution of this shell until it receives a
851 SIGCONT signal. The -f option says not to complain if
855 GNU Last change: 1993 September 16 13
862 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
866 this is a login shell; just suspend anyway. The return
867 status is 0 unless the shell is a login shell and -f is
868 not supplied, or if job control is not enabled.
870 test _
\be_
\bx_
\bp_
\br
872 Return a status of 0 (true) or 1 (false) depending on
873 the evaluation of the conditional expression _
\be_
\bx_
\bp_
\br.
874 Expressions may be unary or binary. Unary expressions
875 are often used to examine the status of a file. There
876 are string operators and numeric comparison operators
877 as well. Each operator and operand must be a separate
878 argument. If _
\bf_
\bi_
\bl_
\be is of the form /dev/fd/_
\bn, then file
879 descriptor _
\bn is checked.
881 True if _
\bf_
\bi_
\bl_
\be exists and is block special.
883 True if _
\bf_
\bi_
\bl_
\be exists and is character special.
885 True if _
\bf_
\bi_
\bl_
\be exists and is a directory.
887 True if _
\bf_
\bi_
\bl_
\be exists.
889 True if _
\bf_
\bi_
\bl_
\be exists and is a regular file.
891 True if _
\bf_
\bi_
\bl_
\be exists and is set-group-id.
893 True if _
\bf_
\bi_
\bl_
\be has its ``sticky'' bit set.
895 True if _
\bf_
\bi_
\bl_
\be exists and is a symbolic link.
897 True if _
\bf_
\bi_
\bl_
\be exists and is a named pipe.
899 True if _
\bf_
\bi_
\bl_
\be exists and is readable.
901 True if _
\bf_
\bi_
\bl_
\be exists and has a size greater than
904 True if _
\bf_
\bi_
\bl_
\be exists and is a socket.
906 True if _
\bf_
\bd is opened on a terminal.
908 True if _
\bf_
\bi_
\bl_
\be exists and its set-user-id bit is
911 True if _
\bf_
\bi_
\bl_
\be exists and is writable.
913 True if _
\bf_
\bi_
\bl_
\be exists and is executable.
915 True if _
\bf_
\bi_
\bl_
\be exists and is owned by the effective
921 GNU Last change: 1993 September 16 14
928 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
932 True if _
\bf_
\bi_
\bl_
\be exists and is owned by the effective
934 _
\bf_
\bi_
\bl_
\be_
\b1 -nt _
\bf_
\bi_
\bl_
\be_
\b2
935 True if _
\bf_
\bi_
\bl_
\be_
\b1 is newer (according to modification
936 date) than _
\bf_
\bi_
\bl_
\be_
\b2.
937 _
\bf_
\bi_
\bl_
\be_
\b1 -ot _
\bf_
\bi_
\bl_
\be_
\b2
938 True if _
\bf_
\bi_
\bl_
\be_
\b1 is older than file2.
939 _
\bf_
\bi_
\bl_
\be_
\b1 -ef _
\bf_
\bi_
\bl_
\be
940 True if _
\bf_
\bi_
\bl_
\be_
\b1 and _
\bf_
\bi_
\bl_
\be_
\b2 have the same device and
942 -z _
\bs_
\bt_
\br_
\bi_
\bn_
\bg
943 True if the length of _
\bs_
\bt_
\br_
\bi_
\bn_
\bg is zero.
944 -n _
\bs_
\bt_
\br_
\bi_
\bn_
\bg
945 _
\bs_
\bt_
\br_
\bi_
\bn_
\bg
946 True if the length of _
\bs_
\bt_
\br_
\bi_
\bn_
\bg is non-zero.
947 _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b1 = _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b2
948 True if the strings are equal.
949 _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b1 != _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b2
950 True if the strings are not equal.
952 True if _
\be_
\bx_
\bp_
\br is false.
953 _
\be_
\bx_
\bp_
\br_
\b1 -a _
\be_
\bx_
\bp_
\br_
\b2
954 True if both _
\be_
\bx_
\bp_
\br_
\b1 AND _
\be_
\bx_
\bp_
\br_
\b2 are true.
955 _
\be_
\bx_
\bp_
\br_
\b1 -o _
\be_
\bx_
\bp_
\br_
\b2
956 True if either _
\be_
\bx_
\bp_
\br_
\b1 OR _
\be_
\bx_
\bp_
\br_
\b2 is true.
957 _
\ba_
\br_
\bg_
\b1 OP _
\ba_
\br_
\bg_
\b2
958 OP is one of -eq, -ne, -lt, -le, -gt, or -ge.
959 These arithmetic binary operators return true if
960 _
\ba_
\br_
\bg_
\b1 is equal, not-equal, less-than, less-than-
961 or-equal, greater-than, or greater-than-or-equal
962 than _
\ba_
\br_
\bg_
\b2, respectively. _
\bA_
\br_
\bg_
\b1 and _
\ba_
\br_
\bg_
\b2 may be
963 positive integers, negative integers, or the spe-
964 cial expression -l _
\bs_
\bt_
\br_
\bi_
\bn_
\bg, which evaluates to the
965 length of _
\bs_
\bt_
\br_
\bi_
\bn_
\bg.
968 Print the accumulated user and system times for the
969 shell and for processes run from the shell. The return
972 trap [-l] [_
\ba_
\br_
\bg] [_
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc]
973 The command _
\ba_
\br_
\bg is to be read and executed when the
974 shell receives signal(s) _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc. If _
\ba_
\br_
\bg is absent or
975 -, all specified signals are reset to their original
976 values (the values they had upon entrance to the
977 shell). If _
\ba_
\br_
\bg is the null string this signal is
978 ignored by the shell and by the commands it invokes.
979 _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc is either a signal name defined in <_
\bs_
\bi_
\bg_
\bn_
\ba_
\bl._
\bh>,
980 or a signal number. If _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc is EXIT (0) the command
981 _
\ba_
\br_
\bg is executed on exit from the shell. With no argu-
982 ments, trap prints the list of commands associated with
983 each signal number. The -l option causes the shell to
987 GNU Last change: 1993 September 16 15
994 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
998 print a list of signal names and their corresponding
999 numbers. An argument of -- disables option checking
1000 for the rest of the arguments. Signals ignored upon
1001 entry to the shell cannot be trapped or reset. Trapped
1002 signals are reset to their original values in a child
1003 process when it is created. The return status is false
1004 if either the trap name or number is invalid; otherwise
1007 type [-all] [-type | -path] _
\bn_
\ba_
\bm_
\be [_
\bn_
\ba_
\bm_
\be ...]
1008 With no options, indicate how each _
\bn_
\ba_
\bm_
\be would be inter-
1009 preted if used as a command name. If the -type flag is
1010 used, type prints a phrase which is one of _
\ba_
\bl_
\bi_
\ba_
\bs, _
\bk_
\be_
\by_
\b-
1011 _
\bw_
\bo_
\br_
\bd, _
\bf_
\bu_
\bn_
\bc_
\bt_
\bi_
\bo_
\bn, _
\bb_
\bu_
\bi_
\bl_
\bt_
\bi_
\bn, or _
\bf_
\bi_
\bl_
\be if _
\bn_
\ba_
\bm_
\be is an alias,
1012 shell reserved word, function, builtin, or disk file,
1013 respectively. If the name is not found, then nothing is
1014 printed, and an exit status of false is returned. If
1015 the -path flag is used, type either returns the name of
1016 the disk file that would be executed if _
\bn_
\ba_
\bm_
\be were
1017 specified as a command name, or nothing if -type would
1018 not return _
\bf_
\bi_
\bl_
\be. If a command is hashed, -path prints
1019 the hashed value, not necessarily the file that appears
1020 first in PATH. If the -all flag is used, type prints
1021 all of the places that contain an executable named
1022 _
\bn_
\ba_
\bm_
\be. This includes aliases and functions, if and only
1023 if the -path flag is not also used. The table of
1024 hashed commands is not consulted when using -all. type
1025 accepts -a, -t, and -p in place of -all, -type, and
1026 -path, respectively. An argument of -- disables option
1027 checking for the rest of the arguments. type returns
1028 true if any of the arguments are found, false if none
1031 ulimit [-SHacdfmstpnuv [_
\bl_
\bi_
\bm_
\bi_
\bt]]
1032 Ulimit provides control over the resources available to
1033 the shell and to processes started by it, on systems
1034 that allow such control. The value of _
\bl_
\bi_
\bm_
\bi_
\bt can be a
1035 number in the unit specified for the resource, or the
1036 value unlimited. The H and S options specify that the
1037 hard or soft limit is set for the given resource. A
1038 hard limit cannot be increased once it is set; a soft
1039 limit may be increased up to the value of the hard
1040 limit. If neither H nor S is specified, the command
1041 applies to the soft limit. If _
\bl_
\bi_
\bm_
\bi_
\bt is omitted, the
1042 current value of the soft limit of the resource is
1043 printed, unless the H option is given. When more than
1044 one resource is specified, the limit name and unit is
1045 printed before the value. Other options are inter-
1047 -a all current limits are reported
1048 -c the maximum size of core files created
1049 -d the maximum size of a process's data segment
1053 GNU Last change: 1993 September 16 16
1060 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
1064 -f the maximum size of files created by the shell
1065 -m the maximum resident set size
1066 -s the maximum stack size
1067 -t the maximum amount of cpu time in seconds
1068 -p the pipe size in 512-byte blocks (this may not be
1070 -n the maximum number of open file descriptors (most
1071 systems do not allow this value to be set, only
1073 -u the maximum number of processes available to a
1075 -v The maximum amount of virtual memory available to
1078 An argument of -- disables option checking for the rest
1079 of the arguments. If _
\bl_
\bi_
\bm_
\bi_
\bt is given, it is the new
1080 value of the specified resource (the -a option is
1081 display only). If no option is given, then -f is
1082 assumed. Values are in 1024-byte increments, except
1083 for -t, which is in seconds, -p, which is in units of
1084 512-byte blocks, and -n and -u, which are unscaled
1085 values. The return status is 0 unless an illegal
1086 option is encountered, a non-numeric argument other
1087 than unlimited is supplied as _
\bl_
\bi_
\bm_
\bi_
\bt, or an error occurs
1088 while setting a new limit.
1090 umask [-S] [_
\bm_
\bo_
\bd_
\be]
1091 The user file-creation mask is set to _
\bm_
\bo_
\bd_
\be. If _
\bm_
\bo_
\bd_
\be
1092 begins with a digit, it is interpreted as an octal
1093 number; otherwise it is interpreted as a symbolic mode
1094 mask similar to that accepted by _
\bc_
\bh_
\bm_
\bo_
\bd(1). If _
\bm_
\bo_
\bd_
\be is
1095 omitted, or if the -S option is supplied, the current
1096 value of the mask is printed. The -S option causes the
1097 mask to be printed in symbolic form; the default output
1098 is an octal number. An argument of -- disables option
1099 checking for the rest of the arguments. The return
1100 status is 0 if the mode was successfully changed or if
1101 no _
\bm_
\bo_
\bd_
\be argument was supplied, and false otherwise.
1103 unalias [-a] [_
\bn_
\ba_
\bm_
\be ...]
1104 Remove _
\bn_
\ba_
\bm_
\bes from the list of defined aliases. If -a
1105 is supplied, all alias definitions are removed. The
1106 return value is true unless a supplied _
\bn_
\ba_
\bm_
\be is not a
1109 unset [-fv] [_
\bn_
\ba_
\bm_
\be ...]
1110 For each _
\bn_
\ba_
\bm_
\be, remove the corresponding variable or,
1111 given the -f option, function. An argument of -- dis-
1112 ables option checking for the rest of the arguments.
1113 Note that PATH, IFS, PPID, PS1, PS2, UID, and EUID can-
1114 not be unset. If any of RANDOM, SECONDS, LINENO, or
1115 HISTCMD are unset, they lose their special properties,
1119 GNU Last change: 1993 September 16 17
1126 BASH_BUILTINS(1) USER COMMANDS BASH_BUILTINS(1)
1130 even if they are subsequently reset. The exit status
1131 is true unless a _
\bn_
\ba_
\bm_
\be does not exist or is non-
1135 Wait for the specified process and return its termina-
1136 tion status. _
\bn may be a process ID or a job specifica-
1137 tion; if a job spec is given, all processes in that
1138 job's pipeline are waited for. If _
\bn is not given, all
1139 currently active child processes are waited for, and
1140 the return status is zero. If _
\bn specifies a non-
1141 existant process or job, the return status is 127.
1142 Otherwise, the return status is the exit status of the
1143 last process or job waited for.
1185 GNU Last change: 1993 September 16 18