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6e70dbff | 1 | \" |
726f6388 JA |
2 | .\" MAN PAGE COMMENTS to |
3 | .\" | |
4 | .\" Chet Ramey | |
5 | .\" Information Network Services | |
6 | .\" Case Western Reserve University | |
d3a24ed2 | 7 | .\" chet@po.CWRU.Edu |
726f6388 | 8 | .\" |
1569c106 | 9 | .\" Last Change: Fri Jul 15 23:15:01 EDT 2005 |
726f6388 JA |
10 | .\" |
11 | .\" bash_builtins, strip all but Built-Ins section | |
12 | .if \n(zZ=1 .ig zZ | |
bb70624e | 13 | .if \n(zY=1 .ig zY |
1569c106 | 14 | .TH BASH 1 "2005 Jul 15" "GNU Bash-3.1-devel" |
726f6388 JA |
15 | .\" |
16 | .\" There's some problem with having a `@' | |
17 | .\" in a tagged paragraph with the BSD man macros. | |
18 | .\" It has to do with `@' appearing in the }1 macro. | |
19 | .\" This is a problem on 4.3 BSD and Ultrix, but Sun | |
20 | .\" appears to have fixed it. | |
21 | .\" If you're seeing the characters | |
22 | .\" `@u-3p' appearing before the lines reading | |
23 | .\" `possible-hostname-completions | |
24 | .\" and `complete-hostname' down in READLINE, | |
25 | .\" then uncomment this redefinition. | |
26 | .\" | |
27 | .de }1 | |
28 | .ds ]X \&\\*(]B\\ | |
29 | .nr )E 0 | |
30 | .if !"\\$1"" .nr )I \\$1n | |
31 | .}f | |
32 | .ll \\n(LLu | |
33 | .in \\n()Ru+\\n(INu+\\n()Iu | |
34 | .ti \\n(INu | |
35 | .ie !\\n()Iu+\\n()Ru-\w\a\\*(]X\au-3p \{\\*(]X | |
36 | .br\} | |
37 | .el \\*(]X\h\a|\\n()Iu+\\n()Ru\a\c | |
38 | .}f | |
39 | .. | |
40 | .\" | |
41 | .\" File Name macro. This used to be `.PN', for Path Name, | |
42 | .\" but Sun doesn't seem to like that very much. | |
43 | .\" | |
44 | .de FN | |
45 | \fI\|\\$1\|\fP | |
46 | .. | |
47 | .SH NAME | |
ccc6cda3 | 48 | bash \- GNU Bourne-Again SHell |
726f6388 JA |
49 | .SH SYNOPSIS |
50 | .B bash | |
51 | [options] | |
52 | [file] | |
53 | .SH COPYRIGHT | |
6e70dbff CR |
54 | .if n Bash is Copyright (C) 1989-2005 by the Free Software Foundation, Inc. |
55 | .if t Bash is Copyright \(co 1989-2005 by the Free Software Foundation, Inc. | |
726f6388 JA |
56 | .SH DESCRIPTION |
57 | .B Bash | |
ccc6cda3 | 58 | is an \fBsh\fR-compatible command language interpreter that |
726f6388 JA |
59 | executes commands read from the standard input or from a file. |
60 | .B Bash | |
61 | also incorporates useful features from the \fIKorn\fP and \fIC\fP | |
62 | shells (\fBksh\fP and \fBcsh\fP). | |
63 | .PP | |
64 | .B Bash | |
cce855bc | 65 | is intended to be a conformant implementation of the IEEE |
ccc6cda3 | 66 | POSIX Shell and Tools specification (IEEE Working Group 1003\.2). |
726f6388 | 67 | .SH OPTIONS |
ccc6cda3 | 68 | In addition to the single-character shell options documented in the |
726f6388 | 69 | description of the \fBset\fR builtin command, \fBbash\fR |
cce855bc | 70 | interprets the following options when it is invoked: |
726f6388 JA |
71 | .PP |
72 | .PD 0 | |
73 | .TP 10 | |
74 | .BI \-c "\| string\^" | |
ccc6cda3 | 75 | If the |
726f6388 | 76 | .B \-c |
cce855bc | 77 | option is present, then commands are read from |
726f6388 JA |
78 | .IR string . |
79 | If there are arguments after the | |
80 | .IR string , | |
81 | they are assigned to the positional parameters, starting with | |
82 | .BR $0 . | |
83 | .TP | |
7117c2d2 JA |
84 | .B \-i |
85 | If the | |
86 | .B \-i | |
87 | option is present, the shell is | |
88 | .IR interactive . | |
89 | .TP | |
90 | .B \-l | |
91 | Make | |
92 | .B bash | |
93 | act as if it had been invoked as a login shell (see | |
94 | .SM | |
95 | .B INVOCATION | |
96 | below). | |
97 | .TP | |
ccc6cda3 JA |
98 | .B \-r |
99 | If the | |
100 | .B \-r | |
cce855bc | 101 | option is present, the shell becomes |
ccc6cda3 JA |
102 | .I restricted |
103 | (see | |
104 | .SM | |
105 | .B "RESTRICTED SHELL" | |
106 | below). | |
107 | .TP | |
726f6388 JA |
108 | .B \-s |
109 | If the | |
110 | .B \-s | |
cce855bc | 111 | option is present, or if no arguments remain after option |
726f6388 JA |
112 | processing, then commands are read from the standard input. |
113 | This option allows the positional parameters to be set | |
114 | when invoking an interactive shell. | |
115 | .TP | |
ccc6cda3 JA |
116 | .B \-D |
117 | A list of all double-quoted strings preceded by \fB$\fP | |
22e63b05 | 118 | is printed on the standard output. |
ccc6cda3 JA |
119 | These are the strings that |
120 | are subject to language translation when the current locale | |
28ef6c31 | 121 | is not \fBC\fP or \fBPOSIX\fP. |
ccc6cda3 JA |
122 | This implies the \fB\-n\fP option; no commands will be executed. |
123 | .TP | |
f73dda09 JA |
124 | .B [\-+]O [\fIshopt_option\fP] |
125 | \fIshopt_option\fP is one of the shell options accepted by the | |
126 | \fBshopt\fP builtin (see | |
127 | .SM | |
128 | .B SHELL BUILTIN COMMANDS | |
129 | below). | |
130 | If \fIshopt_option\fP is present, \fB\-O\fP sets the value of that option; | |
131 | \fB+O\fP unsets it. | |
132 | If \fIshopt_option\fP is not supplied, the names and values of the shell | |
133 | options accepted by \fBshopt\fP are printed on the standard output. | |
134 | If the invocation option is \fB+O\fP, the output is displayed in a format | |
135 | that may be reused as input. | |
136 | .TP | |
ccc6cda3 JA |
137 | .B \-\- |
138 | A | |
139 | .B \-\- | |
726f6388 JA |
140 | signals the end of options and disables further option processing. |
141 | Any arguments after the | |
726f6388 | 142 | .B \-\- |
ccc6cda3 JA |
143 | are treated as filenames and arguments. An argument of |
144 | .B \- | |
145 | is equivalent to \fB\-\-\fP. | |
726f6388 JA |
146 | .PD |
147 | .PP | |
148 | .B Bash | |
ccc6cda3 JA |
149 | also interprets a number of multi-character options. |
150 | These options must appear on the command line before the | |
7117c2d2 | 151 | single-character options to be recognized. |
726f6388 JA |
152 | .PP |
153 | .PD 0 | |
726f6388 | 154 | .TP |
d3a24ed2 CR |
155 | .B \-\-debugger |
156 | Arrange for the debugger profile to be executed before the shell | |
2206f89a CR |
157 | starts. |
158 | Turns on extended debugging mode (see the description of the | |
d3a24ed2 CR |
159 | .B extdebug |
160 | option to the | |
161 | .B shopt | |
2206f89a CR |
162 | builtin below) |
163 | and shell function tracing (see the description of the | |
d3a24ed2 CR |
164 | \fB\-o functrace\fP option to the |
165 | .B set | |
166 | builtin below). | |
167 | .TP | |
cce855bc JA |
168 | .B \-\-dump\-po\-strings |
169 | Equivalent to \fB\-D\fP, but the output is in the GNU \fIgettext\fP | |
170 | \fBpo\fP (portable object) file format. | |
171 | .TP | |
ccc6cda3 JA |
172 | .B \-\-dump\-strings |
173 | Equivalent to \fB\-D\fP. | |
174 | .TP | |
175 | .B \-\-help | |
176 | Display a usage message on standard output and exit successfully. | |
177 | .TP | |
28ef6c31 | 178 | \fB\-\-init\-file\fP \fIfile\fP |
7117c2d2 | 179 | .PD 0 |
28ef6c31 JA |
180 | .TP |
181 | \fB\-\-rcfile\fP \fIfile\fP | |
182 | .PD | |
183 | Execute commands from | |
184 | .I file | |
185 | instead of the standard personal initialization file | |
186 | .I ~/.bashrc | |
187 | if the shell is interactive (see | |
188 | .SM | |
189 | .B INVOCATION | |
190 | below). | |
191 | .TP | |
ccc6cda3 | 192 | .B \-\-login |
7117c2d2 | 193 | Equivalent to \fB\-l\fP. |
ccc6cda3 JA |
194 | .TP |
195 | .B \-\-noediting | |
196 | Do not use the GNU | |
197 | .B readline | |
bb70624e | 198 | library to read command lines when the shell is interactive. |
ccc6cda3 JA |
199 | .TP |
200 | .B \-\-noprofile | |
201 | Do not read either the system-wide startup file | |
726f6388 JA |
202 | .FN /etc/profile |
203 | or any of the personal initialization files | |
204 | .IR ~/.bash_profile , | |
205 | .IR ~/.bash_login , | |
206 | or | |
207 | .IR ~/.profile . | |
208 | By default, | |
209 | .B bash | |
ccc6cda3 | 210 | reads these files when it is invoked as a login shell (see |
726f6388 JA |
211 | .SM |
212 | .B INVOCATION | |
213 | below). | |
214 | .TP | |
ccc6cda3 JA |
215 | .B \-\-norc |
216 | Do not read and execute the personal initialization file | |
217 | .I ~/.bashrc | |
218 | if the shell is interactive. | |
219 | This option is on by default if the shell is invoked as | |
220 | .BR sh . | |
221 | .TP | |
222 | .B \-\-posix | |
223 | Change the behavior of \fBbash\fP where the default operation differs | |
28ef6c31 | 224 | from the POSIX 1003.2 standard to match the standard (\fIposix mode\fP). |
726f6388 | 225 | .TP |
ccc6cda3 JA |
226 | .B \-\-restricted |
227 | The shell becomes restricted (see | |
228 | .SM | |
229 | .B "RESTRICTED SHELL" | |
726f6388 JA |
230 | below). |
231 | .TP | |
ccc6cda3 JA |
232 | .B \-\-verbose |
233 | Equivalent to \fB\-v\fP. | |
726f6388 | 234 | .TP |
ccc6cda3 JA |
235 | .B \-\-version |
236 | Show version information for this instance of | |
237 | .B bash | |
238 | on the standard output and exit successfully. | |
726f6388 JA |
239 | .PD |
240 | .SH ARGUMENTS | |
241 | If arguments remain after option processing, and neither the | |
242 | .B \-c | |
243 | nor the | |
244 | .B \-s | |
245 | option has been supplied, the first argument is assumed to | |
ccc6cda3 JA |
246 | be the name of a file containing shell commands. |
247 | If | |
726f6388 JA |
248 | .B bash |
249 | is invoked in this fashion, | |
250 | .B $0 | |
251 | is set to the name of the file, and the positional parameters | |
252 | are set to the remaining arguments. | |
253 | .B Bash | |
254 | reads and executes commands from this file, then exits. | |
ccc6cda3 JA |
255 | \fBBash\fP's exit status is the exit status of the last command |
256 | executed in the script. | |
257 | If no commands are executed, the exit status is 0. | |
f73dda09 JA |
258 | An attempt is first made to open the file in the current directory, and, |
259 | if no file is found, then the shell searches the directories in | |
260 | .SM | |
261 | .B PATH | |
262 | for the script. | |
ccc6cda3 JA |
263 | .SH INVOCATION |
264 | A \fIlogin shell\fP is one whose first character of argument zero is a | |
265 | .BR \- , | |
266 | or one started with the | |
267 | .B \-\-login | |
268 | option. | |
269 | .PP | |
bb70624e JA |
270 | An \fIinteractive\fP shell is one started without non-option arguments |
271 | and without the | |
272 | .B \-c | |
273 | option | |
da5b17cd | 274 | whose standard input and error are |
ccc6cda3 JA |
275 | both connected to terminals (as determined by |
276 | .IR isatty (3)), | |
277 | or one started with the | |
278 | .B \-i | |
279 | option. | |
280 | .SM | |
281 | .B PS1 | |
282 | is set and | |
283 | .B $\- | |
284 | includes | |
285 | .B i | |
286 | if | |
287 | .B bash | |
288 | is interactive, | |
289 | allowing a shell script or a startup file to test this state. | |
290 | .PP | |
291 | The following paragraphs describe how | |
292 | .B bash | |
293 | executes its startup files. | |
294 | If any of the files exist but cannot be read, | |
295 | .B bash | |
296 | reports an error. | |
297 | Tildes are expanded in file names as described below under | |
298 | .B "Tilde Expansion" | |
299 | in the | |
300 | .SM | |
301 | .B EXPANSION | |
302 | section. | |
303 | .PP | |
304 | When | |
305 | .B bash | |
b72432fd JA |
306 | is invoked as an interactive login shell, or as a non-interactive shell |
307 | with the \fB\-\-login\fP option, it first reads and | |
d166f048 JA |
308 | executes commands from the file \fI/etc/profile\fP, if that |
309 | file exists. | |
ccc6cda3 JA |
310 | After reading that file, it looks for \fI~/.bash_profile\fP, |
311 | \fI~/.bash_login\fP, and \fI~/.profile\fP, in that order, and reads | |
312 | and executes commands from the first one that exists and is readable. | |
313 | The | |
314 | .B \-\-noprofile | |
315 | option may be used when the shell is started to inhibit this behavior. | |
316 | .PP | |
317 | When a login shell exits, | |
318 | .B bash | |
319 | reads and executes commands from the file \fI~/.bash_logout\fP, if it | |
320 | exists. | |
321 | .PP | |
322 | When an interactive shell that is not a login shell is started, | |
323 | .B bash | |
324 | reads and executes commands from \fI~/.bashrc\fP, if that file exists. | |
325 | This may be inhibited by using the | |
326 | .B \-\-norc | |
327 | option. | |
328 | The \fB\-\-rcfile\fP \fIfile\fP option will force | |
329 | .B bash | |
330 | to read and execute commands from \fIfile\fP instead of \fI~/.bashrc\fP. | |
331 | .PP | |
332 | When | |
333 | .B bash | |
334 | is started non-interactively, to run a shell script, for example, it | |
335 | looks for the variable | |
336 | .SM | |
337 | .B BASH_ENV | |
338 | in the environment, expands its value if it appears there, and uses the | |
339 | expanded value as the name of a file to read and execute. | |
340 | .B Bash | |
341 | behaves as if the following command were executed: | |
342 | .sp .5 | |
343 | .RS | |
28ef6c31 JA |
344 | .if t \f(CWif [ \-n "$BASH_ENV" ]; then . "$BASH_ENV"; fi\fP |
345 | .if n if [ \-n "$BASH_ENV" ]; then . "$BASH_ENV"; fi | |
ccc6cda3 JA |
346 | .RE |
347 | .sp .5 | |
348 | but the value of the | |
349 | .SM | |
350 | .B PATH | |
351 | variable is not used to search for the file name. | |
352 | .PP | |
353 | If | |
354 | .B bash | |
355 | is invoked with the name | |
356 | .BR sh , | |
357 | it tries to mimic the startup behavior of historical versions of | |
358 | .B sh | |
359 | as closely as possible, | |
360 | while conforming to the POSIX standard as well. | |
b72432fd JA |
361 | When invoked as an interactive login shell, or a non-interactive |
362 | shell with the \fB\-\-login\fP option, it first attempts to | |
cce855bc | 363 | read and execute commands from |
ccc6cda3 JA |
364 | .I /etc/profile |
365 | and | |
366 | .IR ~/.profile , | |
367 | in that order. | |
368 | The | |
369 | .B \-\-noprofile | |
370 | option may be used to inhibit this behavior. | |
371 | When invoked as an interactive shell with the name | |
372 | .BR sh , | |
373 | .B bash | |
374 | looks for the variable | |
375 | .SM | |
376 | .BR ENV , | |
377 | expands its value if it is defined, and uses the | |
378 | expanded value as the name of a file to read and execute. | |
379 | Since a shell invoked as | |
380 | .B sh | |
381 | does not attempt to read and execute commands from any other startup | |
382 | files, the | |
383 | .B \-\-rcfile | |
384 | option has no effect. | |
385 | A non-interactive shell invoked with the name | |
386 | .B sh | |
b72432fd | 387 | does not attempt to read any other startup files. |
ccc6cda3 JA |
388 | When invoked as |
389 | .BR sh , | |
390 | .B bash | |
391 | enters | |
392 | .I posix | |
393 | mode after the startup files are read. | |
394 | .PP | |
395 | When | |
396 | .B bash | |
397 | is started in | |
398 | .I posix | |
399 | mode, as with the | |
400 | .B \-\-posix | |
401 | command line option, it follows the POSIX standard for startup files. | |
cce855bc | 402 | In this mode, interactive shells expand the |
ccc6cda3 JA |
403 | .SM |
404 | .B ENV | |
cce855bc | 405 | variable and commands are read and executed from the file |
ccc6cda3 JA |
406 | whose name is the expanded value. |
407 | No other startup files are read. | |
ccc6cda3 JA |
408 | .PP |
409 | .B Bash | |
410 | attempts to determine when it is being run by the remote shell | |
411 | daemon, usually \fIrshd\fP. | |
412 | If | |
413 | .B bash | |
414 | determines it is being run by \fIrshd\fP, it reads and executes | |
415 | commands from \fI~/.bashrc\fP, if that file exists and is readable. | |
416 | It will not do this if invoked as \fBsh\fP. | |
417 | The | |
418 | .B \-\-norc | |
419 | option may be used to inhibit this behavior, and the | |
420 | .B \-\-rcfile | |
421 | option may be used to force another file to be read, but | |
422 | \fIrshd\fP does not generally invoke the shell with those options | |
423 | or allow them to be specified. | |
b72432fd JA |
424 | .PP |
425 | If the shell is started with the effective user (group) id not equal to the | |
426 | real user (group) id, and the \fB\-p\fP option is not supplied, no startup | |
f73dda09 JA |
427 | files are read, shell functions are not inherited from the environment, the |
428 | .SM | |
429 | .B SHELLOPTS | |
430 | variable, if it appears in the environment, is ignored, | |
b72432fd JA |
431 | and the effective user id is set to the real user id. |
432 | If the \fB\-p\fP option is supplied at invocation, the startup behavior is | |
433 | the same, but the effective user id is not reset. | |
726f6388 | 434 | .SH DEFINITIONS |
ccc6cda3 JA |
435 | .PP |
436 | The following definitions are used throughout the rest of this | |
437 | document. | |
726f6388 JA |
438 | .PD 0 |
439 | .TP | |
440 | .B blank | |
441 | A space or tab. | |
442 | .TP | |
443 | .B word | |
444 | A sequence of characters considered as a single unit by the shell. | |
445 | Also known as a | |
446 | .BR token . | |
447 | .TP | |
448 | .B name | |
449 | A | |
450 | .I word | |
451 | consisting only of alphanumeric characters and underscores, and | |
452 | beginning with an alphabetic character or an underscore. Also | |
453 | referred to as an | |
454 | .BR identifier . | |
455 | .TP | |
456 | .B metacharacter | |
457 | A character that, when unquoted, separates words. One of the following: | |
458 | .br | |
459 | .RS | |
460 | .PP | |
461 | .if t \fB| & ; ( ) < > space tab\fP | |
462 | .if n \fB| & ; ( ) < > space tab\fP | |
463 | .RE | |
464 | .PP | |
465 | .TP | |
466 | .B control operator | |
467 | A \fItoken\fP that performs a control function. It is one of the following | |
468 | symbols: | |
469 | .RS | |
470 | .PP | |
ccc6cda3 | 471 | .if t \fB\(bv\(bv & && ; ;; ( ) | <newline>\fP |
726f6388 JA |
472 | .if n \fB|| & && ; ;; ( ) | <newline>\fP |
473 | .RE | |
474 | .PD | |
475 | .SH "RESERVED WORDS" | |
476 | \fIReserved words\fP are words that have a special meaning to the shell. | |
477 | The following words are recognized as reserved when unquoted and either | |
478 | the first word of a simple command (see | |
479 | .SM | |
480 | .B SHELL GRAMMAR | |
481 | below) or the third word of a | |
482 | .B case | |
483 | or | |
484 | .B for | |
485 | command: | |
486 | .if t .RS | |
487 | .PP | |
488 | .B | |
cce855bc JA |
489 | .if n ! case do done elif else esac fi for function if in select then until while { } time [[ ]] |
490 | .if t ! case do done elif else esac fi for function if in select then until while { } time [[ ]] | |
726f6388 | 491 | .if t .RE |
726f6388 JA |
492 | .SH "SHELL GRAMMAR" |
493 | .SS Simple Commands | |
494 | .PP | |
495 | A \fIsimple command\fP is a sequence of optional variable assignments | |
ccc6cda3 | 496 | followed by \fBblank\fP-separated words and redirections, and |
726f6388 | 497 | terminated by a \fIcontrol operator\fP. The first word |
f73dda09 JA |
498 | specifies the command to be executed, and is passed as argument zero. |
499 | The remaining words are passed as arguments to the invoked command. | |
726f6388 JA |
500 | .PP |
501 | The return value of a \fIsimple command\fP is its exit status, or | |
502 | 128+\fIn\^\fP if the command is terminated by signal | |
503 | .IR n . | |
504 | .SS Pipelines | |
505 | .PP | |
506 | A \fIpipeline\fP is a sequence of one or more commands separated by | |
507 | the character | |
508 | .BR | . | |
509 | The format for a pipeline is: | |
510 | .RS | |
511 | .PP | |
ccc6cda3 | 512 | [\fBtime\fP [\fB\-p\fP]] [ ! ] \fIcommand\fP [ \fB|\fP \fIcommand2\fP ... ] |
726f6388 JA |
513 | .RE |
514 | .PP | |
515 | The standard output of | |
516 | .I command | |
f73dda09 | 517 | is connected via a pipe to the standard input of |
726f6388 JA |
518 | .IR command2 . |
519 | This connection is performed before any redirections specified by the | |
520 | command (see | |
521 | .SM | |
522 | .B REDIRECTION | |
523 | below). | |
524 | .PP | |
d3a24ed2 CR |
525 | The return status of a pipeline is the exit status of the last |
526 | command, unless the \fBpipefail\fP option is enabled. | |
527 | If \fBpipefail\fP is enabled, the pipeline's return status is the | |
528 | value of the last (rightmost) command to exit with a non-zero status, | |
529 | or zero if all commands exit successfully. | |
726f6388 JA |
530 | If the reserved word |
531 | .B ! | |
d3a24ed2 CR |
532 | precedes a pipeline, the exit status of that pipeline is the logical |
533 | negation of the exit status as described above. | |
ccc6cda3 | 534 | The shell waits for all commands in the pipeline to |
726f6388 JA |
535 | terminate before returning a value. |
536 | .PP | |
ccc6cda3 JA |
537 | If the |
538 | .B time | |
539 | reserved word precedes a pipeline, the elapsed as well as user and | |
540 | system time consumed by its execution are reported when the pipeline | |
541 | terminates. | |
542 | The \fB\-p\fP option changes the output format to that specified by POSIX. | |
543 | The | |
544 | .SM | |
545 | .B TIMEFORMAT | |
546 | variable may be set to a format string that specifies how the timing | |
547 | information should be displayed; see the description of | |
548 | .SM | |
549 | .B TIMEFORMAT | |
550 | under | |
551 | .B "Shell Variables" | |
552 | below. | |
553 | .PP | |
726f6388 JA |
554 | Each command in a pipeline is executed as a separate process (i.e., in a |
555 | subshell). | |
556 | .SS Lists | |
557 | .PP | |
558 | A \fIlist\fP is a sequence of one or more pipelines separated by one | |
559 | of the operators | |
560 | .BR ; , | |
561 | .BR & , | |
562 | .BR && , | |
563 | or | |
ccc6cda3 JA |
564 | .BR \(bv\(bv , |
565 | and optionally terminated by one of | |
726f6388 JA |
566 | .BR ; , |
567 | .BR & , | |
568 | or | |
569 | .BR <newline> . | |
570 | .PP | |
571 | Of these list operators, | |
572 | .B && | |
573 | and | |
ccc6cda3 | 574 | .B \(bv\(bv |
726f6388 JA |
575 | have equal precedence, followed by |
576 | .B ; | |
577 | and | |
578 | .BR &, | |
579 | which have equal precedence. | |
580 | .PP | |
7117c2d2 JA |
581 | A sequence of one or more newlines may appear in a \fIlist\fP instead |
582 | of a semicolon to delimit commands. | |
583 | .PP | |
726f6388 JA |
584 | If a command is terminated by the control operator |
585 | .BR & , | |
586 | the shell executes the command in the \fIbackground\fP | |
587 | in a subshell. The shell does not wait for the command to | |
588 | finish, and the return status is 0. Commands separated by a | |
589 | .B ; | |
590 | are executed sequentially; the shell waits for each | |
591 | command to terminate in turn. The return status is the | |
592 | exit status of the last command executed. | |
593 | .PP | |
594 | The control operators | |
595 | .B && | |
596 | and | |
ccc6cda3 | 597 | .B \(bv\(bv |
726f6388 JA |
598 | denote AND lists and OR lists, respectively. |
599 | An AND list has the form | |
600 | .RS | |
601 | .PP | |
bb70624e | 602 | \fIcommand1\fP \fB&&\fP \fIcommand2\fP |
726f6388 JA |
603 | .RE |
604 | .PP | |
605 | .I command2 | |
606 | is executed if, and only if, | |
bb70624e | 607 | .I command1 |
726f6388 JA |
608 | returns an exit status of zero. |
609 | .PP | |
610 | An OR list has the form | |
611 | .RS | |
612 | .PP | |
bb70624e | 613 | \fIcommand1\fP \fB\(bv\(bv\fP \fIcommand2\fP |
726f6388 JA |
614 | .PP |
615 | .RE | |
616 | .PP | |
617 | .I command2 | |
618 | is executed if and only if | |
bb70624e | 619 | .I command1 |
ccc6cda3 | 620 | returns a non-zero exit status. The return status of |
726f6388 JA |
621 | AND and OR lists is the exit status of the last command |
622 | executed in the list. | |
623 | .SS Compound Commands | |
624 | .PP | |
625 | A \fIcompound command\fP is one of the following: | |
626 | .TP | |
627 | (\fIlist\fP) | |
d3a24ed2 CR |
628 | \fIlist\fP is executed in a subshell environment (see |
629 | .SM | |
630 | \fBCOMMAND EXECUTION ENVIRONMENT\fP | |
631 | below). | |
632 | Variable assignments and builtin | |
726f6388 JA |
633 | commands that affect the shell's environment do not remain in effect |
634 | after the command completes. The return status is the exit status of | |
635 | \fIlist\fP. | |
636 | .TP | |
637 | { \fIlist\fP; } | |
ccc6cda3 JA |
638 | \fIlist\fP is simply executed in the current shell environment. |
639 | \fIlist\fP must be terminated with a newline or semicolon. | |
640 | This is known as a \fIgroup command\fP. | |
641 | The return status is the exit status of | |
726f6388 | 642 | \fIlist\fP. |
d3a24ed2 | 643 | Note that unlike the metacharacters \fB(\fP and \fB)\fP, \fB{\fP and |
f73dda09 JA |
644 | \fB}\fP are \fIreserved words\fP and must occur where a reserved |
645 | word is permitted to be recognized. Since they do not cause a word | |
646 | break, they must be separated from \fIlist\fP by whitespace. | |
726f6388 | 647 | .TP |
ccc6cda3 JA |
648 | ((\fIexpression\fP)) |
649 | The \fIexpression\fP is evaluated according to the rules described | |
650 | below under | |
651 | .SM | |
652 | .BR "ARITHMETIC EVALUATION" . | |
653 | If the value of the expression is non-zero, the return status is 0; | |
654 | otherwise the return status is 1. This is exactly equivalent to | |
655 | \fBlet "\fIexpression\fP"\fR. | |
656 | .TP | |
cce855bc JA |
657 | \fB[[\fP \fIexpression\fP \fB]]\fP |
658 | Return a status of 0 or 1 depending on the evaluation of | |
659 | the conditional expression \fIexpression\fP. | |
660 | Expressions are composed of the primaries described below under | |
661 | .SM | |
662 | .BR "CONDITIONAL EXPRESSIONS" . | |
663 | Word splitting and pathname expansion are not performed on the words | |
664 | between the \fB[[\fP and \fB]]\fP; tilde expansion, parameter and | |
665 | variable expansion, arithmetic expansion, command substitution, process | |
666 | substitution, and quote removal are performed. | |
d3a24ed2 CR |
667 | Conditional operators such as \fB\-f\fP must be unquoted to be recognized |
668 | as primaries. | |
cce855bc JA |
669 | .if t .sp 0.5 |
670 | .if n .sp 1 | |
671 | When the \fB==\fP and \fB!=\fP operators are used, the string to the | |
672 | right of the operator is considered a pattern and matched according | |
673 | to the rules described below under \fBPattern Matching\fP. | |
2206f89a CR |
674 | If the shell option |
675 | .B nocasematch | |
676 | is enabled, the match is performed without regard to the case | |
677 | of alphabetic characters. | |
cce855bc JA |
678 | The return value is 0 if the string matches or does not match |
679 | the pattern, respectively, and 1 otherwise. | |
680 | Any part of the pattern may be quoted to force it to be matched as a | |
681 | string. | |
682 | .if t .sp 0.5 | |
683 | .if n .sp 1 | |
d3a24ed2 CR |
684 | An additional binary operator, \fB=~\fP, is available, with the same |
685 | precedence as \fB==\fP and \fB!=\fP. | |
686 | When it is used, the string to the right of the operator is considered | |
687 | an extended regular expression and matched accordingly (as in \fIregex\fP(3)). | |
688 | The return value is 0 if the string matches | |
689 | the pattern, and 1 otherwise. | |
690 | If the regular expression is syntactically incorrect, the conditional | |
691 | expression's return value is 2. | |
692 | If the shell option | |
2206f89a | 693 | .B nocasematch |
d3a24ed2 CR |
694 | is enabled, the match is performed without regard to the case |
695 | of alphabetic characters. | |
696 | Substrings matched by parenthesized subexpressions within the regular | |
697 | expression are saved in the array variable \fBBASH_REMATCH\fP. | |
698 | The element of \fBBASH_REMATCH\fP with index 0 is the portion of the string | |
699 | matching the entire regular expression. | |
700 | The element of \fBBASH_REMATCH\fP with index \fIn\fP is the portion of the | |
701 | string matching the \fIn\fPth parenthesized subexpression. | |
702 | .if t .sp 0.5 | |
703 | .if n .sp 1 | |
cce855bc JA |
704 | Expressions may be combined using the following operators, listed |
705 | in decreasing order of precedence: | |
706 | .if t .sp 0.5 | |
707 | .if n .sp 1 | |
708 | .RS | |
709 | .PD 0 | |
710 | .TP | |
711 | .B ( \fIexpression\fP ) | |
712 | Returns the value of \fIexpression\fP. | |
713 | This may be used to override the normal precedence of operators. | |
714 | .TP | |
715 | .B ! \fIexpression\fP | |
716 | True if | |
717 | .I expression | |
718 | is false. | |
719 | .TP | |
720 | \fIexpression1\fP \fB&&\fP \fIexpression2\fP | |
721 | True if both | |
722 | .I expression1 | |
723 | and | |
724 | .I expression2 | |
725 | are true. | |
726 | .TP | |
727 | .if t \fIexpression1\fP \fB\(bv\(bv\fP \fIexpression2\fP | |
728 | .if n \fIexpression1\fP \fB||\fP \fIexpression2\fP | |
729 | True if either | |
730 | .I expression1 | |
731 | or | |
732 | .I expression2 | |
733 | is true. | |
734 | .PD | |
cce855bc JA |
735 | .LP |
736 | The \fB&&\fP and | |
737 | .if t \fB\(bv\(bv\fP | |
738 | .if n \fB||\fP | |
7117c2d2 | 739 | operators do not evaluate \fIexpression2\fP if the value of |
cce855bc JA |
740 | \fIexpression1\fP is sufficient to determine the return value of |
741 | the entire conditional expression. | |
f73dda09 | 742 | .RE |
cce855bc | 743 | .TP |
b72432fd | 744 | \fBfor\fP \fIname\fP [ \fBin\fP \fIword\fP ] ; \fBdo\fP \fIlist\fP ; \fBdone\fP |
726f6388 | 745 | The list of words following \fBin\fP is expanded, generating a list |
bb70624e JA |
746 | of items. |
747 | The variable \fIname\fP is set to each element of this list | |
748 | in turn, and \fIlist\fP is executed each time. | |
749 | If the \fBin\fP \fIword\fP is omitted, the \fBfor\fP command executes | |
750 | \fIlist\fP once for each positional parameter that is set (see | |
726f6388 JA |
751 | .SM |
752 | .B PARAMETERS | |
753 | below). | |
cce855bc JA |
754 | The return status is the exit status of the last command that executes. |
755 | If the expansion of the items following \fBin\fP results in an empty | |
756 | list, no commands are executed, and the return status is 0. | |
726f6388 | 757 | .TP |
bb70624e JA |
758 | \fBfor\fP (( \fIexpr1\fP ; \fIexpr2\fP ; \fIexpr3\fP )) ; \fBdo\fP \fIlist\fP ; \fBdone\fP |
759 | First, the arithmetic expression \fIexpr1\fP is evaluated according | |
760 | to the rules described below under | |
761 | .SM | |
762 | .BR "ARITHMETIC EVALUATION" . | |
763 | The arithmetic expression \fIexpr2\fP is then evaluated repeatedly | |
764 | until it evaluates to zero. | |
765 | Each time \fIexpr2\fP evaluates to a non-zero value, \fIlist\fP is | |
766 | executed and the arithmetic expression \fIexpr3\fP is evaluated. | |
767 | If any expression is omitted, it behaves as if it evaluates to 1. | |
768 | The return value is the exit status of the last command in \fIlist\fP | |
769 | that is executed, or false if any of the expressions is invalid. | |
770 | .TP | |
b72432fd | 771 | \fBselect\fP \fIname\fP [ \fBin\fP \fIword\fP ] ; \fBdo\fP \fIlist\fP ; \fBdone\fP |
726f6388 JA |
772 | The list of words following \fBin\fP is expanded, generating a list |
773 | of items. The set of expanded words is printed on the standard | |
774 | error, each preceded by a number. If the \fBin\fP | |
775 | \fIword\fP is omitted, the positional parameters are printed (see | |
776 | .SM | |
777 | .B PARAMETERS | |
778 | below). The | |
779 | .B PS3 | |
780 | prompt is then displayed and a line read from the standard input. | |
ccc6cda3 | 781 | If the line consists of a number corresponding to one of |
726f6388 JA |
782 | the displayed words, then the value of |
783 | .I name | |
784 | is set to that word. If the line is empty, the words and prompt | |
785 | are displayed again. If EOF is read, the command completes. Any | |
786 | other value read causes | |
787 | .I name | |
788 | to be set to null. The line read is saved in the variable | |
789 | .BR REPLY . | |
790 | The | |
791 | .I list | |
792 | is executed after each selection until a | |
793 | .B break | |
726f6388 JA |
794 | command is executed. |
795 | The exit status of | |
796 | .B select | |
797 | is the exit status of the last command executed in | |
798 | .IR list , | |
799 | or zero if no commands were executed. | |
800 | .TP | |
bb70624e | 801 | \fBcase\fP \fIword\fP \fBin\fP [ [(] \fIpattern\fP [ \fB|\fP \fIpattern\fP ] \ |
726f6388 JA |
802 | ... ) \fIlist\fP ;; ] ... \fBesac\fP |
803 | A \fBcase\fP command first expands \fIword\fP, and tries to match | |
804 | it against each \fIpattern\fP in turn, using the same matching rules | |
805 | as for pathname expansion (see | |
806 | .B Pathname Expansion | |
2206f89a CR |
807 | below). |
808 | If the shell option | |
809 | .B nocasematch | |
810 | is enabled, the match is performed without regard to the case | |
811 | of alphabetic characters. | |
812 | When a match is found, the | |
726f6388 JA |
813 | corresponding \fIlist\fP is executed. After the first match, no |
814 | subsequent matches are attempted. The exit status is zero if no | |
ccc6cda3 | 815 | pattern matches. Otherwise, it is the exit status of the |
726f6388 JA |
816 | last command executed in \fIlist\fP. |
817 | .TP | |
ccc6cda3 JA |
818 | \fBif\fP \fIlist\fP; \fBthen\fP \fIlist;\fP \ |
819 | [ \fBelif\fP \fIlist\fP; \fBthen\fP \fIlist\fP; ] ... \ | |
820 | [ \fBelse\fP \fIlist\fP; ] \fBfi\fP | |
726f6388 JA |
821 | The |
822 | .B if | |
823 | .I list | |
824 | is executed. If its exit status is zero, the | |
825 | \fBthen\fP \fIlist\fP is executed. Otherwise, each \fBelif\fP | |
826 | \fIlist\fP is executed in turn, and if its exit status is zero, | |
827 | the corresponding \fBthen\fP \fIlist\fP is executed and the | |
828 | command completes. Otherwise, the \fBelse\fP \fIlist\fP is | |
829 | executed, if present. The exit status is the exit status of the | |
830 | last command executed, or zero if no condition tested true. | |
831 | .TP | |
ccc6cda3 | 832 | \fBwhile\fP \fIlist\fP; \fBdo\fP \fIlist\fP; \fBdone\fP |
7117c2d2 | 833 | .PD 0 |
726f6388 | 834 | .TP |
ccc6cda3 | 835 | \fBuntil\fP \fIlist\fP; \fBdo\fP \fIlist\fP; \fBdone\fP |
726f6388 JA |
836 | .PD |
837 | The \fBwhile\fP command continuously executes the \fBdo\fP | |
838 | \fIlist\fP as long as the last command in \fIlist\fP returns | |
839 | an exit status of zero. The \fBuntil\fP command is identical | |
840 | to the \fBwhile\fP command, except that the test is negated; | |
841 | the | |
842 | .B do | |
843 | .I list | |
844 | is executed as long as the last command in | |
845 | .I list | |
ccc6cda3 | 846 | returns a non-zero exit status. |
726f6388 JA |
847 | The exit status of the \fBwhile\fP and \fBuntil\fP commands |
848 | is the exit status | |
849 | of the last \fBdo\fP \fIlist\fP command executed, or zero if | |
850 | none was executed. | |
d3a24ed2 CR |
851 | .SS Shell Function Definitions |
852 | .PP | |
853 | A shell function is an object that is called like a simple command and | |
854 | executes a compound command with a new set of positional parameters. | |
855 | Shell functions are declared as follows: | |
856 | .TP | |
857 | [ \fBfunction\fP ] \fIname\fP () \fIcompound\-command\fP [\fIredirection\fP] | |
858 | This defines a function named \fIname\fP. | |
859 | The reserved word \fBfunction\fP is optional. | |
860 | If the \fBfunction\fP reserved word is supplied, the parentheses are optional. | |
861 | The \fIbody\fP of the function is the compound command | |
862 | .I compound\-command | |
863 | (see \fBCompound Commands\fP above). | |
864 | That command is usually a \fIlist\fP of commands between { and }, but | |
865 | may be any command listed under \fBCompound Commands\fP above. | |
866 | \fIcompound\-command\fP is executed whenever \fIname\fP is specified as the | |
867 | name of a simple command. | |
868 | Any redirections (see | |
869 | .SM | |
870 | .B REDIRECTION | |
871 | below) specified when a function is defined are performed | |
872 | when the function is executed. | |
873 | The exit status of a function definition is zero unless a syntax error | |
874 | occurs or a readonly function with the same name already exists. | |
875 | When executed, the exit status of a function is the exit status of the | |
876 | last command executed in the body. (See | |
726f6388 JA |
877 | .SM |
878 | .B FUNCTIONS | |
879 | below.) | |
880 | .SH COMMENTS | |
ccc6cda3 JA |
881 | In a non-interactive shell, or an interactive shell in which the |
882 | .B interactive_comments | |
883 | option to the | |
884 | .B shopt | |
885 | builtin is enabled (see | |
886 | .SM | |
887 | .B "SHELL BUILTIN COMMANDS" | |
888 | below), a word beginning with | |
726f6388 JA |
889 | .B # |
890 | causes that word and all remaining characters on that line to | |
891 | be ignored. An interactive shell without the | |
ccc6cda3 | 892 | .B interactive_comments |
ccc6cda3 JA |
893 | option enabled does not allow comments. The |
894 | .B interactive_comments | |
895 | option is on by default in interactive shells. | |
726f6388 JA |
896 | .SH QUOTING |
897 | \fIQuoting\fP is used to remove the special meaning of certain | |
898 | characters or words to the shell. Quoting can be used to | |
899 | disable special treatment for special characters, to prevent | |
900 | reserved words from being recognized as such, and to prevent | |
901 | parameter expansion. | |
902 | .PP | |
903 | Each of the \fImetacharacters\fP listed above under | |
904 | .SM | |
905 | .B DEFINITIONS | |
bb70624e JA |
906 | has special meaning to the shell and must be quoted if it is to |
907 | represent itself. | |
908 | .PP | |
5c96a638 CR |
909 | When the command history expansion facilities are being used |
910 | (see | |
911 | .SM | |
912 | .B HISTORY EXPANSION | |
913 | below), the | |
bb70624e JA |
914 | \fIhistory expansion\fP character, usually \fB!\fP, must be quoted |
915 | to prevent history expansion. | |
916 | .PP | |
917 | There are three quoting mechanisms: the | |
726f6388 JA |
918 | .IR "escape character" , |
919 | single quotes, and double quotes. | |
920 | .PP | |
921 | A non-quoted backslash (\fB\e\fP) is the | |
922 | .IR "escape character" . | |
923 | It preserves the literal value of the next character that follows, | |
924 | with the exception of <newline>. If a \fB\e\fP<newline> pair | |
cce855bc JA |
925 | appears, and the backslash is not itself quoted, the \fB\e\fP<newline> |
926 | is treated as a line continuation (that is, it is removed from the | |
927 | input stream and effectively ignored). | |
726f6388 JA |
928 | .PP |
929 | Enclosing characters in single quotes preserves the literal value | |
930 | of each character within the quotes. A single quote may not occur | |
931 | between single quotes, even when preceded by a backslash. | |
932 | .PP | |
933 | Enclosing characters in double quotes preserves the literal value | |
934 | of all characters within the quotes, with the exception of | |
935 | .BR $ , | |
936 | .BR ` , | |
5c96a638 CR |
937 | .BR \e , |
938 | and, when history expansion is enabled, | |
939 | .BR ! . | |
726f6388 JA |
940 | The characters |
941 | .B $ | |
942 | and | |
943 | .B ` | |
944 | retain their special meaning within double quotes. The backslash | |
945 | retains its special meaning only when followed by one of the following | |
946 | characters: | |
947 | .BR $ , | |
948 | .BR ` , | |
949 | \^\fB"\fP\^, | |
950 | .BR \e , | |
951 | or | |
952 | .BR <newline> . | |
953 | A double quote may be quoted within double quotes by preceding it with | |
954 | a backslash. | |
5c96a638 CR |
955 | If enabled, history expansion will be performed unless an |
956 | .B ! | |
957 | appearing in double quotes is escaped using a backslash. | |
958 | The backslash preceding the | |
959 | .B ! | |
960 | is not removed. | |
726f6388 JA |
961 | .PP |
962 | The special parameters | |
963 | .B * | |
964 | and | |
965 | .B @ | |
966 | have special meaning when in double | |
967 | quotes (see | |
968 | .SM | |
969 | .B PARAMETERS | |
970 | below). | |
ccc6cda3 JA |
971 | .PP |
972 | Words of the form \fB$\fP'\fIstring\fP' are treated specially. The | |
973 | word expands to \fIstring\fP, with backslash-escaped characters replaced | |
f75912ae | 974 | as specified by the ANSI C standard. Backslash escape sequences, if |
ccc6cda3 JA |
975 | present, are decoded as follows: |
976 | .RS | |
977 | .PD 0 | |
978 | .TP | |
979 | .B \ea | |
980 | alert (bell) | |
981 | .TP | |
982 | .B \eb | |
983 | backspace | |
984 | .TP | |
985 | .B \ee | |
986 | an escape character | |
987 | .TP | |
988 | .B \ef | |
989 | form feed | |
990 | .TP | |
991 | .B \en | |
992 | new line | |
993 | .TP | |
994 | .B \er | |
995 | carriage return | |
996 | .TP | |
997 | .B \et | |
998 | horizontal tab | |
999 | .TP | |
1000 | .B \ev | |
1001 | vertical tab | |
1002 | .TP | |
1003 | .B \e\e | |
1004 | backslash | |
bb70624e JA |
1005 | .TP |
1006 | .B \e' | |
1007 | single quote | |
ccc6cda3 JA |
1008 | .TP |
1009 | .B \e\fInnn\fP | |
f73dda09 | 1010 | the eight-bit character whose value is the octal value \fInnn\fP |
cce855bc JA |
1011 | (one to three digits) |
1012 | .TP | |
f73dda09 JA |
1013 | .B \ex\fIHH\fP |
1014 | the eight-bit character whose value is the hexadecimal value \fIHH\fP | |
1015 | (one or two hex digits) | |
7117c2d2 JA |
1016 | .TP |
1017 | .B \ec\fIx\fP | |
1018 | a control-\fIx\fP character | |
ccc6cda3 JA |
1019 | .PD |
1020 | .RE | |
1021 | .LP | |
bb70624e | 1022 | The expanded result is single-quoted, as if the dollar sign had |
ccc6cda3 JA |
1023 | not been present. |
1024 | .PP | |
1025 | A double-quoted string preceded by a dollar sign (\fB$\fP) will cause | |
1026 | the string to be translated according to the current locale. | |
1027 | If the current locale is \fBC\fP or \fBPOSIX\fP, the dollar sign | |
1028 | is ignored. | |
1029 | If the string is translated and replaced, the replacement is | |
1030 | double-quoted. | |
726f6388 JA |
1031 | .SH PARAMETERS |
1032 | A | |
1033 | .I parameter | |
ccc6cda3 JA |
1034 | is an entity that stores values. |
1035 | It can be a | |
726f6388 JA |
1036 | .IR name , |
1037 | a number, or one of the special characters listed below under | |
1038 | .BR "Special Parameters" . | |
d3a24ed2 | 1039 | A |
726f6388 JA |
1040 | .I variable |
1041 | is a parameter denoted by a | |
1042 | .IR name . | |
f73dda09 JA |
1043 | A variable has a \fIvalue\fP and zero or more \fIattributes\fP. |
1044 | Attributes are assigned using the | |
1045 | .B declare | |
1046 | builtin command (see | |
1047 | .B declare | |
1048 | below in | |
1049 | .SM | |
1050 | .BR "SHELL BUILTIN COMMANDS" ). | |
726f6388 JA |
1051 | .PP |
1052 | A parameter is set if it has been assigned a value. The null string is | |
1053 | a valid value. Once a variable is set, it may be unset only by using | |
1054 | the | |
1055 | .B unset | |
1056 | builtin command (see | |
1057 | .SM | |
1058 | .B SHELL BUILTIN COMMANDS | |
1059 | below). | |
1060 | .PP | |
1061 | A | |
1062 | .I variable | |
1063 | may be assigned to by a statement of the form | |
1064 | .RS | |
1065 | .PP | |
1066 | \fIname\fP=[\fIvalue\fP] | |
1067 | .RE | |
1068 | .PP | |
1069 | If | |
1070 | .I value | |
1071 | is not given, the variable is assigned the null string. All | |
1072 | .I values | |
bb70624e JA |
1073 | undergo tilde expansion, parameter and variable expansion, |
1074 | command substitution, arithmetic expansion, and quote | |
ccc6cda3 JA |
1075 | removal (see |
1076 | .SM | |
1077 | .B EXPANSION | |
1078 | below). If the variable has its | |
cce855bc | 1079 | .B integer |
f73dda09 | 1080 | attribute set, then |
726f6388 | 1081 | .I value |
d3a24ed2 | 1082 | is evaluated as an arithmetic expression even if the $((...)) expansion is |
cce855bc | 1083 | not used (see |
ccc6cda3 JA |
1084 | .B "Arithmetic Expansion" |
1085 | below). | |
1086 | Word splitting is not performed, with the exception | |
726f6388 JA |
1087 | of \fB"$@"\fP as explained below under |
1088 | .BR "Special Parameters" . | |
1089 | Pathname expansion is not performed. | |
f73dda09 | 1090 | Assignment statements may also appear as arguments to the |
5e13499c | 1091 | .BR alias , |
f73dda09 JA |
1092 | .BR declare , |
1093 | .BR typeset , | |
1094 | .BR export , | |
1095 | .BR readonly , | |
1096 | and | |
1097 | .B local | |
1098 | builtin commands. | |
d11b8b46 CR |
1099 | .PP |
1100 | In the context where an assignment statement is assigning a value | |
1101 | to a shell variable or array index, the += operator can be used to | |
1102 | append to or add to the variable's previous value. | |
1103 | When += is applied to a variable for which the integer attribute has been | |
1104 | set, \fIvalue\fP is evaluated as an arithmetic expression and added to the | |
1105 | variable's current value, which is also evaluated. | |
1106 | When += is applied to an array variable using compound assignment (see | |
1107 | .B Arrays | |
1108 | below), the | |
1109 | variable's value is not unset (as it is when using =), and new values are | |
1110 | appended to the array beginning at one greater than the array's maximum index. | |
1111 | When applied to a string-valued variable, \fIvalue\fP is expanded and | |
1112 | appended to the variable's value. | |
726f6388 JA |
1113 | .SS Positional Parameters |
1114 | .PP | |
1115 | A | |
1116 | .I positional parameter | |
1117 | is a parameter denoted by one or more | |
1118 | digits, other than the single digit 0. Positional parameters are | |
1119 | assigned from the shell's arguments when it is invoked, | |
1120 | and may be reassigned using the | |
1121 | .B set | |
1122 | builtin command. Positional parameters may not be assigned to | |
1123 | with assignment statements. The positional parameters are | |
1124 | temporarily replaced when a shell function is executed (see | |
1125 | .SM | |
1126 | .B FUNCTIONS | |
1127 | below). | |
1128 | .PP | |
1129 | When a positional parameter consisting of more than a single | |
1130 | digit is expanded, it must be enclosed in braces (see | |
1131 | .SM | |
1132 | .B EXPANSION | |
1133 | below). | |
1134 | .SS Special Parameters | |
1135 | .PP | |
1136 | The shell treats several parameters specially. These parameters may | |
1137 | only be referenced; assignment to them is not allowed. | |
1138 | .PD 0 | |
1139 | .TP | |
1140 | .B * | |
1141 | Expands to the positional parameters, starting from one. When the | |
1142 | expansion occurs within double quotes, it expands to a single word | |
1143 | with the value of each parameter separated by the first character | |
1144 | of the | |
1145 | .SM | |
1146 | .B IFS | |
cce855bc JA |
1147 | special variable. That is, "\fB$*\fP" is equivalent |
1148 | to "\fB$1\fP\fIc\fP\fB$2\fP\fIc\fP\fB...\fP", where | |
726f6388 JA |
1149 | .I c |
1150 | is the first character of the value of the | |
1151 | .SM | |
1152 | .B IFS | |
1153 | variable. If | |
1154 | .SM | |
1155 | .B IFS | |
d166f048 JA |
1156 | is unset, the parameters are separated by spaces. |
1157 | If | |
1158 | .SM | |
1159 | .B IFS | |
1160 | is null, the parameters are joined without intervening separators. | |
726f6388 JA |
1161 | .TP |
1162 | .B @ | |
1163 | Expands to the positional parameters, starting from one. When the | |
cce855bc JA |
1164 | expansion occurs within double quotes, each parameter expands to a |
1165 | separate word. That is, "\fB$@\fP" is equivalent to | |
1166 | "\fB$1\fP" "\fB$2\fP" ... | |
be7d8f2d CR |
1167 | If the double-quoted expansion occurs within a word, the expansion of |
1168 | the first parameter is joined with the beginning part of the original | |
1169 | word, and the expansion of the last parameter is joined with the last | |
1170 | part of the original word. | |
cce855bc | 1171 | When there are no positional parameters, "\fB$@\fP" and |
726f6388 JA |
1172 | .B $@ |
1173 | expand to nothing (i.e., they are removed). | |
1174 | .TP | |
1175 | .B # | |
1176 | Expands to the number of positional parameters in decimal. | |
1177 | .TP | |
1178 | .B ? | |
1179 | Expands to the status of the most recently executed foreground | |
1180 | pipeline. | |
1181 | .TP | |
1182 | .B \- | |
1183 | Expands to the current option flags as specified upon invocation, | |
1184 | by the | |
1185 | .B set | |
1186 | builtin command, or those set by the shell itself | |
1187 | (such as the | |
1188 | .B \-i | |
cce855bc | 1189 | option). |
726f6388 JA |
1190 | .TP |
1191 | .B $ | |
1192 | Expands to the process ID of the shell. In a () subshell, it | |
1193 | expands to the process ID of the current shell, not the | |
1194 | subshell. | |
1195 | .TP | |
1196 | .B ! | |
1197 | Expands to the process ID of the most recently executed background | |
1198 | (asynchronous) command. | |
1199 | .TP | |
1200 | .B 0 | |
1201 | Expands to the name of the shell or shell script. This is set at | |
1202 | shell initialization. If | |
1203 | .B bash | |
1204 | is invoked with a file of commands, | |
1205 | .B $0 | |
1206 | is set to the name of that file. If | |
1207 | .B bash | |
1208 | is started with the | |
1209 | .B \-c | |
1210 | option, then | |
1211 | .B $0 | |
1212 | is set to the first argument after the string to be | |
1213 | executed, if one is present. Otherwise, it is set | |
ccc6cda3 | 1214 | to the file name used to invoke |
726f6388 JA |
1215 | .BR bash , |
1216 | as given by argument zero. | |
1217 | .TP | |
1218 | .B _ | |
cc87ba64 CR |
1219 | At shell startup, set to the absolute pathname used to invoke the |
1220 | shell or shell script being executed as passed in the environment | |
1221 | or argument list. | |
ccc6cda3 JA |
1222 | Subsequently, expands to the last argument to the previous command, |
1223 | after expansion. | |
cc87ba64 CR |
1224 | Also set to the full pathname used to invoke each command executed |
1225 | and placed in the environment exported to that command. | |
ccc6cda3 JA |
1226 | When checking mail, this parameter holds the name of the mail file |
1227 | currently being checked. | |
726f6388 JA |
1228 | .PD |
1229 | .SS Shell Variables | |
1230 | .PP | |
1231 | The following variables are set by the shell: | |
1232 | .PP | |
1233 | .PD 0 | |
1234 | .TP | |
726f6388 | 1235 | .B BASH |
ccc6cda3 | 1236 | Expands to the full file name used to invoke this instance of |
726f6388 JA |
1237 | .BR bash . |
1238 | .TP | |
d3a24ed2 CR |
1239 | .B BASH_ARGC |
1240 | An array variable whose values are the number of parameters in each | |
2206f89a CR |
1241 | frame of the current bash execution call stack. |
1242 | The number of | |
d3a24ed2 | 1243 | parameters to the current subroutine (shell function or script executed |
2206f89a CR |
1244 | with \fB.\fP or \fBsource\fP) is at the top of the stack. |
1245 | When a subroutine is executed, the number of parameters passed is pushed onto | |
d3a24ed2 | 1246 | \fBBASH_ARGC\fP. |
2206f89a CR |
1247 | The shell sets \fBBASH_ARGC\fP only when in extended debugging mode |
1248 | (see the description of the | |
1249 | .B extdebug | |
1250 | option to the | |
1251 | .B shopt | |
1252 | builtin below) | |
d3a24ed2 CR |
1253 | .TP |
1254 | .B BASH_ARGV | |
1255 | An array variable containing all of the parameters in the current bash | |
1256 | execution call stack. The final parameter of the last subroutine call | |
1257 | is at the top of the stack; the first parameter of the initial call is | |
1258 | at the bottom. When a subroutine is executed, the parameters supplied | |
1259 | are pushed onto \fBBASH_ARGV\fP. | |
2206f89a CR |
1260 | The shell sets \fBBASH_ARGV\fP only when in extended debugging mode |
1261 | (see the description of the | |
1262 | .B extdebug | |
1263 | option to the | |
1264 | .B shopt | |
1265 | builtin below) | |
d3a24ed2 CR |
1266 | .TP |
1267 | .B BASH_COMMAND | |
1268 | The command currently being executed or about to be executed, unless the | |
1269 | shell is executing a command as the result of a trap, | |
1270 | in which case it is the command executing at the time of the trap. | |
1271 | .TP | |
1272 | .B BASH_EXECUTION_STRING | |
1273 | The command argument to the \fB\-c\fP invocation option. | |
1274 | .TP | |
1275 | .B BASH_LINENO | |
1276 | An array variable whose members are the line numbers in source files | |
be7d8f2d | 1277 | corresponding to each member of \fBFUNCNAME\fP. |
d3a24ed2 | 1278 | \fB${BASH_LINENO[\fP\fI$i\fP\fB]}\fP is the line number in the source |
633e5c6d CR |
1279 | file where \fB${FUNCNAME[\fP\fI$ifP\fB]}\fP was called. |
1280 | The corresponding source file name is \fB${BASH_SOURCE[\fP\fI$i\fP\fB]}\fB. | |
d3a24ed2 CR |
1281 | Use \fBLINENO\fP to obtain the current line number. |
1282 | .TP | |
1283 | .B BASH_REMATCH | |
1284 | An array variable whose members are assigned by the \fB=~\fP binary | |
1285 | operator to the \fB[[\fP conditional command. | |
1286 | The element with index 0 is the portion of the string | |
1287 | matching the entire regular expression. | |
1288 | The element with index \fIn\fP is the portion of the | |
1289 | string matching the \fIn\fPth parenthesized subexpression. | |
1290 | This variable is read-only. | |
1291 | .TP | |
1292 | .B BASH_SOURCE | |
1293 | An array variable whose members are the source filenames corresponding | |
1294 | to the elements in the \fBFUNCNAME\fP array variable. | |
1295 | .TP | |
1296 | .B BASH_SUBSHELL | |
1297 | Incremented by one each time a subshell or subshell environment is spawned. | |
1298 | The initial value is 0. | |
1299 | .TP | |
ccc6cda3 | 1300 | .B BASH_VERSINFO |
cce855bc JA |
1301 | A readonly array variable whose members hold version information for |
1302 | this instance of | |
ccc6cda3 JA |
1303 | .BR bash . |
1304 | The values assigned to the array members are as follows: | |
1305 | .sp .5 | |
1306 | .RS | |
1307 | .PD 0 | |
1308 | .TP 24 | |
1309 | .B BASH_VERSINFO[\fR0\fP] | |
1310 | The major version number (the \fIrelease\fP). | |
1311 | .TP | |
1312 | .B BASH_VERSINFO[\fR1\fP] | |
1313 | The minor version number (the \fIversion\fP). | |
1314 | .TP | |
1315 | .B BASH_VERSINFO[\fR2\fP] | |
1316 | The patch level. | |
1317 | .TP | |
1318 | .B BASH_VERSINFO[\fR3\fP] | |
1319 | The build version. | |
1320 | .TP | |
1321 | .B BASH_VERSINFO[\fR4\fP] | |
1322 | The release status (e.g., \fIbeta1\fP). | |
1323 | .TP | |
1324 | .B BASH_VERSINFO[\fR5\fP] | |
1325 | The value of \fBMACHTYPE\fP. | |
1326 | .PD | |
1327 | .RE | |
1328 | .TP | |
f73dda09 JA |
1329 | .B BASH_VERSION |
1330 | Expands to a string describing the version of this instance of | |
1331 | .BR bash . | |
726f6388 | 1332 | .TP |
f73dda09 JA |
1333 | .B COMP_CWORD |
1334 | An index into \fB${COMP_WORDS}\fP of the word containing the current | |
1335 | cursor position. | |
1336 | This variable is available only in shell functions invoked by the | |
1337 | programmable completion facilities (see \fBProgrammable Completion\fP | |
1338 | below). | |
1339 | .TP | |
1340 | .B COMP_LINE | |
1341 | The current command line. | |
1342 | This variable is available only in shell functions and external | |
1343 | commands invoked by the | |
1344 | programmable completion facilities (see \fBProgrammable Completion\fP | |
1345 | below). | |
1346 | .TP | |
1347 | .B COMP_POINT | |
1348 | The index of the current cursor position relative to the beginning of | |
1349 | the current command. | |
1350 | If the current cursor position is at the end of the current command, | |
1351 | the value of this variable is equal to \fB${#COMP_LINE}\fP. | |
1352 | This variable is available only in shell functions and external | |
1353 | commands invoked by the | |
1354 | programmable completion facilities (see \fBProgrammable Completion\fP | |
1355 | below). | |
1356 | .TP | |
d3a24ed2 CR |
1357 | .B COMP_WORDBREAKS |
1358 | The set of characters that the Readline library treats as word | |
1359 | separators when performing word completion. | |
1360 | If | |
1361 | .SM | |
1362 | .B COMP_WORDBREAKS | |
1363 | is unset, it loses its special properties, even if it is | |
1364 | subsequently reset. | |
1365 | .TP | |
f73dda09 JA |
1366 | .B COMP_WORDS |
1367 | An array variable (see \fBArrays\fP below) consisting of the individual | |
1368 | words in the current command line. | |
1369 | This variable is available only in shell functions invoked by the | |
1370 | programmable completion facilities (see \fBProgrammable Completion\fP | |
1371 | below). | |
1372 | .TP | |
1373 | .B DIRSTACK | |
1374 | An array variable (see | |
1375 | .B Arrays | |
1376 | below) containing the current contents of the directory stack. | |
1377 | Directories appear in the stack in the order they are displayed by the | |
1378 | .B dirs | |
1379 | builtin. | |
1380 | Assigning to members of this array variable may be used to modify | |
1381 | directories already in the stack, but the | |
1382 | .B pushd | |
1383 | and | |
1384 | .B popd | |
1385 | builtins must be used to add and remove directories. | |
1386 | Assignment to this variable will not change the current directory. | |
726f6388 JA |
1387 | If |
1388 | .SM | |
f73dda09 | 1389 | .B DIRSTACK |
726f6388 JA |
1390 | is unset, it loses its special properties, even if it is |
1391 | subsequently reset. | |
1392 | .TP | |
f73dda09 JA |
1393 | .B EUID |
1394 | Expands to the effective user ID of the current user, initialized at | |
1395 | shell startup. This variable is readonly. | |
1396 | .TP | |
1397 | .B FUNCNAME | |
d3a24ed2 CR |
1398 | An array variable containing the names of all shell functions |
1399 | currently in the execution call stack. | |
1400 | The element with index 0 is the name of any currently-executing | |
1401 | shell function. | |
1402 | The bottom-most element is "main". | |
f73dda09 JA |
1403 | This variable exists only when a shell function is executing. |
1404 | Assignments to | |
726f6388 | 1405 | .SM |
f73dda09 JA |
1406 | .B FUNCNAME |
1407 | have no effect and return an error status. | |
726f6388 JA |
1408 | If |
1409 | .SM | |
f73dda09 | 1410 | .B FUNCNAME |
726f6388 JA |
1411 | is unset, it loses its special properties, even if it is |
1412 | subsequently reset. | |
1413 | .TP | |
f73dda09 JA |
1414 | .B GROUPS |
1415 | An array variable containing the list of groups of which the current | |
1416 | user is a member. | |
1417 | Assignments to | |
1418 | .SM | |
1419 | .B GROUPS | |
1420 | have no effect and return an error status. | |
726f6388 JA |
1421 | If |
1422 | .SM | |
f73dda09 | 1423 | .B GROUPS |
726f6388 JA |
1424 | is unset, it loses its special properties, even if it is |
1425 | subsequently reset. | |
1426 | .TP | |
1427 | .B HISTCMD | |
1428 | The history number, or index in the history list, of the current | |
ccc6cda3 JA |
1429 | command. |
1430 | If | |
726f6388 JA |
1431 | .SM |
1432 | .B HISTCMD | |
1433 | is unset, it loses its special properties, even if it is | |
1434 | subsequently reset. | |
1435 | .TP | |
f73dda09 JA |
1436 | .B HOSTNAME |
1437 | Automatically set to the name of the current host. | |
bb70624e | 1438 | .TP |
f73dda09 JA |
1439 | .B HOSTTYPE |
1440 | Automatically set to a string that uniquely | |
1441 | describes the type of machine on which | |
1442 | .B bash | |
1443 | is executing. | |
1444 | The default is system-dependent. | |
1445 | .TP | |
1446 | .B LINENO | |
1447 | Each time this parameter is referenced, the shell substitutes | |
1448 | a decimal number representing the current sequential line number | |
1449 | (starting with 1) within a script or function. When not in a | |
1450 | script or function, the value substituted is not guaranteed to | |
1451 | be meaningful. | |
ccc6cda3 JA |
1452 | If |
1453 | .SM | |
f73dda09 | 1454 | .B LINENO |
ccc6cda3 JA |
1455 | is unset, it loses its special properties, even if it is |
1456 | subsequently reset. | |
1457 | .TP | |
f73dda09 JA |
1458 | .B MACHTYPE |
1459 | Automatically set to a string that fully describes the system | |
1460 | type on which | |
1461 | .B bash | |
1462 | is executing, in the standard GNU \fIcpu-company-system\fP format. | |
1463 | The default is system-dependent. | |
1464 | .TP | |
1465 | .B OLDPWD | |
1466 | The previous working directory as set by the | |
1467 | .B cd | |
1468 | command. | |
ccc6cda3 | 1469 | .TP |
726f6388 JA |
1470 | .B OPTARG |
1471 | The value of the last option argument processed by the | |
1472 | .B getopts | |
1473 | builtin command (see | |
1474 | .SM | |
1475 | .B SHELL BUILTIN COMMANDS | |
1476 | below). | |
1477 | .TP | |
1478 | .B OPTIND | |
1479 | The index of the next argument to be processed by the | |
1480 | .B getopts | |
1481 | builtin command (see | |
1482 | .SM | |
1483 | .B SHELL BUILTIN COMMANDS | |
1484 | below). | |
1485 | .TP | |
726f6388 JA |
1486 | .B OSTYPE |
1487 | Automatically set to a string that | |
1488 | describes the operating system on which | |
1489 | .B bash | |
ccc6cda3 JA |
1490 | is executing. |
1491 | The default is system-dependent. | |
1492 | .TP | |
f73dda09 JA |
1493 | .B PIPESTATUS |
1494 | An array variable (see | |
1495 | .B Arrays | |
1496 | below) containing a list of exit status values from the processes | |
1497 | in the most-recently-executed foreground pipeline (which may | |
1498 | contain only a single command). | |
ccc6cda3 | 1499 | .TP |
f73dda09 JA |
1500 | .B PPID |
1501 | The process ID of the shell's parent. This variable is readonly. | |
1502 | .TP | |
1503 | .B PWD | |
1504 | The current working directory as set by the | |
1505 | .B cd | |
1506 | command. | |
1507 | .TP | |
1508 | .B RANDOM | |
1509 | Each time this parameter is referenced, a random integer between | |
1510 | 0 and 32767 is | |
1511 | generated. The sequence of random numbers may be initialized by assigning | |
1512 | a value to | |
1513 | .SM | |
1514 | .BR RANDOM . | |
1515 | If | |
1516 | .SM | |
1517 | .B RANDOM | |
1518 | is unset, it loses its special properties, even if it is | |
1519 | subsequently reset. | |
1520 | .TP | |
1521 | .B REPLY | |
1522 | Set to the line of input read by the | |
1523 | .B read | |
1524 | builtin command when no arguments are supplied. | |
1525 | .TP | |
1526 | .B SECONDS | |
1527 | Each time this parameter is | |
1528 | referenced, the number of seconds since shell invocation is returned. If a | |
1529 | value is assigned to | |
1530 | .SM | |
1531 | .BR SECONDS , | |
1532 | the value returned upon subsequent | |
1533 | references is | |
1534 | the number of seconds since the assignment plus the value assigned. | |
1535 | If | |
1536 | .SM | |
1537 | .B SECONDS | |
1538 | is unset, it loses its special properties, even if it is | |
1539 | subsequently reset. | |
1540 | .TP | |
1541 | .B SHELLOPTS | |
1542 | A colon-separated list of enabled shell options. Each word in | |
1543 | the list is a valid argument for the | |
1544 | .B \-o | |
1545 | option to the | |
1546 | .B set | |
1547 | builtin command (see | |
1548 | .SM | |
1549 | .B "SHELL BUILTIN COMMANDS" | |
1550 | below). The options appearing in | |
ccc6cda3 JA |
1551 | .SM |
1552 | .B SHELLOPTS | |
1553 | are those reported as | |
1554 | .I on | |
1555 | by \fBset \-o\fP. | |
1556 | If this variable is in the environment when | |
1557 | .B bash | |
1558 | starts up, each shell option in the list will be enabled before | |
1559 | reading any startup files. | |
1560 | This variable is read-only. | |
bb70624e | 1561 | .TP |
f73dda09 JA |
1562 | .B SHLVL |
1563 | Incremented by one each time an instance of | |
1564 | .B bash | |
1565 | is started. | |
bb70624e | 1566 | .TP |
f73dda09 JA |
1567 | .B UID |
1568 | Expands to the user ID of the current user, initialized at shell startup. | |
1569 | This variable is readonly. | |
726f6388 JA |
1570 | .PD |
1571 | .PP | |
1572 | The following variables are used by the shell. In some cases, | |
1573 | .B bash | |
1574 | assigns a default value to a variable; these cases are noted | |
1575 | below. | |
1576 | .PP | |
1577 | .PD 0 | |
1578 | .TP | |
d166f048 | 1579 | .B BASH_ENV |
726f6388 JA |
1580 | If this parameter is set when \fBbash\fP is executing a shell script, |
1581 | its value is interpreted as a filename containing commands to | |
1582 | initialize the shell, as in | |
cce855bc | 1583 | .IR ~/.bashrc . |
726f6388 JA |
1584 | The value of |
1585 | .SM | |
d166f048 | 1586 | .B BASH_ENV |
726f6388 | 1587 | is subjected to parameter expansion, command substitution, and arithmetic |
ccc6cda3 | 1588 | expansion before being interpreted as a file name. |
726f6388 JA |
1589 | .SM |
1590 | .B PATH | |
ccc6cda3 | 1591 | is not used to search for the resultant file name. |
726f6388 | 1592 | .TP |
f73dda09 JA |
1593 | .B CDPATH |
1594 | The search path for the | |
1595 | .B cd | |
1596 | command. | |
1597 | This is a colon-separated list of directories in which the shell looks | |
1598 | for destination directories specified by the | |
1599 | .B cd | |
1600 | command. | |
7117c2d2 JA |
1601 | A sample value is |
1602 | .if t \f(CW".:~:/usr"\fP. | |
1603 | .if n ".:~:/usr". | |
726f6388 | 1604 | .TP |
f73dda09 JA |
1605 | .B COLUMNS |
1606 | Used by the \fBselect\fP builtin command to determine the terminal width | |
1607 | when printing selection lists. Automatically set upon receipt of a SIGWINCH. | |
726f6388 | 1608 | .TP |
f73dda09 JA |
1609 | .B COMPREPLY |
1610 | An array variable from which \fBbash\fP reads the possible completions | |
1611 | generated by a shell function invoked by the programmable completion | |
1612 | facility (see \fBProgrammable Completion\fP below). | |
726f6388 | 1613 | .TP |
d3a24ed2 CR |
1614 | .B EMACS |
1615 | If \fBbash\fP finds this variable in the environment when the shell starts | |
1616 | with value | |
1617 | .if t \f(CWt\fP, | |
1618 | .if n "t", | |
1619 | it assumes that the shell is running in an emacs shell buffer and disables | |
1620 | line editing. | |
1621 | .TP | |
f73dda09 JA |
1622 | .B FCEDIT |
1623 | The default editor for the | |
1624 | .B fc | |
1625 | builtin command. | |
726f6388 | 1626 | .TP |
f73dda09 JA |
1627 | .B FIGNORE |
1628 | A colon-separated list of suffixes to ignore when performing | |
1629 | filename completion (see | |
726f6388 | 1630 | .SM |
f73dda09 JA |
1631 | .B READLINE |
1632 | below). | |
1633 | A filename whose suffix matches one of the entries in | |
726f6388 | 1634 | .SM |
f73dda09 JA |
1635 | .B FIGNORE |
1636 | is excluded from the list of matched filenames. | |
7117c2d2 JA |
1637 | A sample value is |
1638 | .if t \f(CW".o:~"\fP. | |
1639 | .if n ".o:~". | |
ccc6cda3 | 1640 | .TP |
f73dda09 JA |
1641 | .B GLOBIGNORE |
1642 | A colon-separated list of patterns defining the set of filenames to | |
1643 | be ignored by pathname expansion. | |
1644 | If a filename matched by a pathname expansion pattern also matches one | |
1645 | of the patterns in | |
726f6388 | 1646 | .SM |
f73dda09 JA |
1647 | .BR GLOBIGNORE , |
1648 | it is removed from the list of matches. | |
1649 | .TP | |
1650 | .B HISTCONTROL | |
d3a24ed2 CR |
1651 | A colon-separated list of values controlling how commands are saved on |
1652 | the history list. | |
1653 | If the list of values includes | |
f73dda09 JA |
1654 | .IR ignorespace , |
1655 | lines which begin with a | |
1656 | .B space | |
d3a24ed2 CR |
1657 | character are not saved in the history list. |
1658 | A value of | |
1659 | .I ignoredups | |
1660 | causes lines matching the previous history entry to not be saved. | |
f73dda09 JA |
1661 | A value of |
1662 | .I ignoreboth | |
d3a24ed2 CR |
1663 | is shorthand for \fIignorespace\fP and \fIignoredups\fP. |
1664 | A value of | |
1665 | .IR erasedups | |
1666 | causes all previous lines matching the current line to be removed from | |
1667 | the history list before that line is saved. | |
1668 | Any value not in the above list is ignored. | |
1669 | If \fBHISTCONTROL\fP is unset, or does not include a valid value, | |
1670 | all lines read by the shell parser are saved on the history list, | |
1671 | subject to the value of | |
f73dda09 JA |
1672 | .BR HISTIGNORE . |
1673 | The second and subsequent lines of a multi-line compound command are | |
1674 | not tested, and are added to the history regardless of the value of | |
1675 | .BR HISTCONTROL . | |
726f6388 JA |
1676 | .TP |
1677 | .B HISTFILE | |
ccc6cda3 | 1678 | The name of the file in which command history is saved (see |
726f6388 JA |
1679 | .SM |
1680 | .B HISTORY | |
ccc6cda3 | 1681 | below). The default value is \fI~/.bash_history\fP. If unset, the |
726f6388 JA |
1682 | command history is not saved when an interactive shell exits. |
1683 | .TP | |
1684 | .B HISTFILESIZE | |
1685 | The maximum number of lines contained in the history file. When this | |
1686 | variable is assigned a value, the history file is truncated, if | |
1687 | necessary, to contain no more than that number of lines. The default | |
ccc6cda3 JA |
1688 | value is 500. The history file is also truncated to this size after |
1689 | writing it when an interactive shell exits. | |
726f6388 | 1690 | .TP |
f73dda09 JA |
1691 | .B HISTIGNORE |
1692 | A colon-separated list of patterns used to decide which command lines | |
1693 | should be saved on the history list. Each pattern is anchored at the | |
1694 | beginning of the line and must match the complete line (no implicit | |
1695 | `\fB*\fP' is appended). Each pattern is tested against the line | |
1696 | after the checks specified by | |
1697 | .B HISTCONTROL | |
1698 | are applied. | |
1699 | In addition to the normal shell pattern matching characters, `\fB&\fP' | |
1700 | matches the previous history line. `\fB&\fP' may be escaped using a | |
1701 | backslash; the backslash is removed before attempting a match. | |
1702 | The second and subsequent lines of a multi-line compound command are | |
1703 | not tested, and are added to the history regardless of the value of | |
1704 | .BR HISTIGNORE . | |
1705 | .TP | |
1706 | .B HISTSIZE | |
1707 | The number of commands to remember in the command history (see | |
1708 | .SM | |
1709 | .B HISTORY | |
1710 | below). The default value is 500. | |
1711 | .TP | |
d3a24ed2 CR |
1712 | .B HISTTIMEFORMAT |
1713 | If this variable is set and not null, its value is used as a format string | |
1714 | for \fIstrftime\fP(3) to print the time stamp associated with each history | |
1715 | entry displayed by the \fBhistory\fP builtin. | |
1716 | If this variable is set, time stamps are written to the history file so | |
1717 | they may be preserved across shell sessions. | |
1718 | .TP | |
f73dda09 JA |
1719 | .B HOME |
1720 | The home directory of the current user; the default argument for the | |
1721 | \fBcd\fP builtin command. | |
1722 | The value of this variable is also used when performing tilde expansion. | |
1723 | .TP | |
1724 | .B HOSTFILE | |
1725 | Contains the name of a file in the same format as | |
1726 | .FN /etc/hosts | |
1727 | that should be read when the shell needs to complete a | |
1728 | hostname. | |
1729 | The list of possible hostname completions may be changed while the | |
1730 | shell is running; | |
1731 | the next time hostname completion is attempted after the | |
1732 | value is changed, | |
726f6388 | 1733 | .B bash |
f73dda09 JA |
1734 | adds the contents of the new file to the existing list. |
1735 | If | |
726f6388 | 1736 | .SM |
f73dda09 JA |
1737 | .B HOSTFILE |
1738 | is set, but has no value, \fBbash\fP attempts to read | |
1739 | .FN /etc/hosts | |
1740 | to obtain the list of possible hostname completions. | |
1741 | When | |
726f6388 | 1742 | .SM |
f73dda09 JA |
1743 | .B HOSTFILE |
1744 | is unset, the hostname list is cleared. | |
1745 | .TP | |
1746 | .B IFS | |
1747 | The | |
1748 | .I Internal Field Separator | |
1749 | that is used | |
1750 | for word splitting after expansion and to | |
1751 | split lines into words with the | |
1752 | .B read | |
1753 | builtin command. The default value is | |
1754 | ``<space><tab><newline>''. | |
1755 | .TP | |
1756 | .B IGNOREEOF | |
1757 | Controls the | |
1758 | action of an interactive shell on receipt of an | |
1759 | .SM | |
1760 | .B EOF | |
1761 | character as the sole input. If set, the value is the number of | |
1762 | consecutive | |
1763 | .SM | |
1764 | .B EOF | |
1765 | characters which must be | |
1766 | typed as the first characters on an input line before | |
1767 | .B bash | |
1768 | exits. If the variable exists but does not have a numeric value, or | |
1769 | has no value, the default value is 10. If it does not exist, | |
1770 | .SM | |
1771 | .B EOF | |
1772 | signifies the end of input to the shell. | |
1773 | .TP | |
1774 | .B INPUTRC | |
1775 | The filename for the | |
1776 | .B readline | |
1777 | startup file, overriding the default of | |
1778 | .FN ~/.inputrc | |
1779 | (see | |
1780 | .SM | |
1781 | .B READLINE | |
1782 | below). | |
726f6388 | 1783 | .TP |
ccc6cda3 JA |
1784 | .B LANG |
1785 | Used to determine the locale category for any category not specifically | |
1786 | selected with a variable starting with \fBLC_\fP. | |
1787 | .TP | |
1788 | .B LC_ALL | |
1789 | This variable overrides the value of \fBLANG\fP and any other | |
1790 | \fBLC_\fP variable specifying a locale category. | |
1791 | .TP | |
1792 | .B LC_COLLATE | |
1793 | This variable determines the collation order used when sorting the | |
cce855bc JA |
1794 | results of pathname expansion, and determines the behavior of range |
1795 | expressions, equivalence classes, and collating sequences within | |
1796 | pathname expansion and pattern matching. | |
1797 | .TP | |
1798 | .B LC_CTYPE | |
1799 | This variable determines the interpretation of characters and the | |
1800 | behavior of character classes within pathname expansion and pattern | |
1801 | matching. | |
ccc6cda3 JA |
1802 | .TP |
1803 | .B LC_MESSAGES | |
1804 | This variable determines the locale used to translate double-quoted | |
1805 | strings preceded by a \fB$\fP. | |
1806 | .TP | |
bb70624e JA |
1807 | .B LC_NUMERIC |
1808 | This variable determines the locale category used for number formatting. | |
1809 | .TP | |
28ef6c31 JA |
1810 | .B LINES |
1811 | Used by the \fBselect\fP builtin command to determine the column length | |
1812 | for printing selection lists. Automatically set upon receipt of a SIGWINCH. | |
1813 | .TP | |
f73dda09 JA |
1814 | .B MAIL |
1815 | If this parameter is set to a file name and the | |
726f6388 | 1816 | .SM |
f73dda09 JA |
1817 | .B MAILPATH |
1818 | variable is not set, | |
726f6388 | 1819 | .B bash |
f73dda09 | 1820 | informs the user of the arrival of mail in the specified file. |
726f6388 | 1821 | .TP |
f73dda09 JA |
1822 | .B MAILCHECK |
1823 | Specifies how | |
1824 | often (in seconds) | |
1825 | .B bash | |
1826 | checks for mail. The default is 60 seconds. When it is time to check | |
1827 | for mail, the shell does so before displaying the primary prompt. | |
1828 | If this variable is unset, or set to a value that is not a number | |
1829 | greater than or equal to zero, the shell disables mail checking. | |
726f6388 | 1830 | .TP |
f73dda09 JA |
1831 | .B MAILPATH |
1832 | A colon-separated list of file names to be checked for mail. | |
1833 | The message to be printed when mail arrives in a particular file | |
1834 | may be specified by separating the file name from the message with a `?'. | |
1835 | When used in the text of the message, \fB$_\fP expands to the name of | |
1836 | the current mailfile. | |
1837 | Example: | |
1838 | .RS | |
1839 | .PP | |
1840 | \fBMAILPATH\fP='/var/mail/bfox?"You have mail":~/shell\-mail?"$_ has mail!"' | |
1841 | .PP | |
1842 | .B Bash | |
1843 | supplies a default value for this variable, but the location of the user | |
1844 | mail files that it uses is system dependent (e.g., /var/mail/\fB$USER\fP). | |
1845 | .RE | |
726f6388 | 1846 | .TP |
f73dda09 JA |
1847 | .B OPTERR |
1848 | If set to the value 1, | |
1849 | .B bash | |
1850 | displays error messages generated by the | |
1851 | .B getopts | |
1852 | builtin command (see | |
726f6388 | 1853 | .SM |
f73dda09 | 1854 | .B SHELL BUILTIN COMMANDS |
ccc6cda3 | 1855 | below). |
726f6388 | 1856 | .SM |
f73dda09 JA |
1857 | .B OPTERR |
1858 | is initialized to 1 each time the shell is invoked or a shell | |
1859 | script is executed. | |
ccc6cda3 | 1860 | .TP |
f73dda09 JA |
1861 | .B PATH |
1862 | The search path for commands. It | |
1863 | is a colon-separated list of directories in which | |
1864 | the shell looks for commands (see | |
ccc6cda3 | 1865 | .SM |
f73dda09 | 1866 | .B COMMAND EXECUTION |
d3a24ed2 CR |
1867 | below). |
1868 | A zero-length (null) directory name in the value of \fBPATH\fP indicates the | |
1869 | current directory. | |
1870 | A null directory name may appear as two adjacent colons, or as an initial | |
1871 | or trailing colon. | |
1872 | The default path is system-dependent, | |
f73dda09 JA |
1873 | and is set by the administrator who installs |
1874 | .BR bash . | |
1875 | A common value is | |
5e13499c CR |
1876 | .if t \f(CW/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin\fP. |
1877 | .if n ``/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin''. | |
726f6388 | 1878 | .TP |
f73dda09 JA |
1879 | .B POSIXLY_CORRECT |
1880 | If this variable is in the environment when \fBbash\fP starts, the shell | |
1881 | enters \fIposix mode\fP before reading the startup files, as if the | |
1882 | .B \-\-posix | |
1883 | invocation option had been supplied. If it is set while the shell is | |
1884 | running, \fBbash\fP enables \fIposix mode\fP, as if the command | |
1885 | .if t \f(CWset -o posix\fP | |
1886 | .if n \fIset -o posix\fP | |
1887 | had been executed. | |
726f6388 | 1888 | .TP |
f73dda09 JA |
1889 | .B PROMPT_COMMAND |
1890 | If set, the value is executed as a command prior to issuing each primary | |
1891 | prompt. | |
ccc6cda3 | 1892 | .TP |
f73dda09 JA |
1893 | .B PS1 |
1894 | The value of this parameter is expanded (see | |
1895 | .SM | |
1896 | .B PROMPTING | |
1897 | below) and used as the primary prompt string. The default value is | |
1898 | ``\fB\es\-\ev\e$ \fP''. | |
726f6388 | 1899 | .TP |
f73dda09 JA |
1900 | .B PS2 |
1901 | The value of this parameter is expanded as with | |
1902 | .B PS1 | |
1903 | and used as the secondary prompt string. The default is | |
1904 | ``\fB> \fP''. | |
1905 | .TP | |
1906 | .B PS3 | |
1907 | The value of this parameter is used as the prompt for the | |
1908 | .B select | |
1909 | command (see | |
726f6388 | 1910 | .SM |
f73dda09 JA |
1911 | .B SHELL GRAMMAR |
1912 | above). | |
726f6388 | 1913 | .TP |
f73dda09 JA |
1914 | .B PS4 |
1915 | The value of this parameter is expanded as with | |
1916 | .B PS1 | |
1917 | and the value is printed before each command | |
726f6388 | 1918 | .B bash |
f73dda09 | 1919 | displays during an execution trace. The first character of |
bb70624e | 1920 | .SM |
f73dda09 JA |
1921 | .B PS4 |
1922 | is replicated multiple times, as necessary, to indicate multiple | |
1923 | levels of indirection. The default is ``\fB+ \fP''. | |
1924 | .TP | |
61deeb13 CR |
1925 | .B SHELL |
1926 | The full pathname to the shell is kept in this environment variable. | |
1927 | If it is not set when the shell starts, | |
1928 | .B bash | |
1929 | assigns to it the full pathname of the current user's login shell. | |
1930 | .TP | |
f73dda09 JA |
1931 | .B TIMEFORMAT |
1932 | The value of this parameter is used as a format string specifying | |
1933 | how the timing information for pipelines prefixed with the | |
1934 | .B time | |
1935 | reserved word should be displayed. | |
1936 | The \fB%\fP character introduces an escape sequence that is | |
1937 | expanded to a time value or other information. | |
1938 | The escape sequences and their meanings are as follows; the | |
1939 | braces denote optional portions. | |
1940 | .sp .5 | |
1941 | .RS | |
1942 | .PD 0 | |
1943 | .TP 10 | |
1944 | .B %% | |
1945 | A literal \fB%\fP. | |
1946 | .TP | |
1947 | .B %[\fIp\fP][l]R | |
1948 | The elapsed time in seconds. | |
1949 | .TP | |
1950 | .B %[\fIp\fP][l]U | |
1951 | The number of CPU seconds spent in user mode. | |
1952 | .TP | |
1953 | .B %[\fIp\fP][l]S | |
1954 | The number of CPU seconds spent in system mode. | |
1955 | .TP | |
1956 | .B %P | |
1957 | The CPU percentage, computed as (%U + %S) / %R. | |
1958 | .PD | |
1959 | .RE | |
1960 | .IP | |
1961 | The optional \fIp\fP is a digit specifying the \fIprecision\fP, | |
1962 | the number of fractional digits after a decimal point. | |
1963 | A value of 0 causes no decimal point or fraction to be output. | |
1964 | At most three places after the decimal point may be specified; | |
1965 | values of \fIp\fP greater than 3 are changed to 3. | |
1966 | If \fIp\fP is not specified, the value 3 is used. | |
1967 | .IP | |
1968 | The optional \fBl\fP specifies a longer format, including | |
1969 | minutes, of the form \fIMM\fPm\fISS\fP.\fIFF\fPs. | |
1970 | The value of \fIp\fP determines whether or not the fraction is | |
1971 | included. | |
1972 | .IP | |
1973 | If this variable is not set, \fBbash\fP acts as if it had the | |
1974 | value \fB$'\enreal\et%3lR\enuser\et%3lU\ensys\t%3lS'\fP. | |
1975 | If the value is null, no timing information is displayed. | |
1976 | A trailing newline is added when the format string is displayed. | |
1977 | .TP | |
1978 | .B TMOUT | |
7117c2d2 JA |
1979 | If set to a value greater than zero, \fBTMOUT\fP is treated as the |
1980 | default timeout for the \fBread\fP builtin. | |
1981 | The \fBselect\fP command terminates if input does not arrive | |
1982 | after \fBTMOUT\fP seconds when input is coming from a terminal. | |
1983 | In an interactive shell, the value is interpreted as the | |
f73dda09 JA |
1984 | number of seconds to wait for input after issuing the primary prompt. |
1985 | .B Bash | |
1986 | terminates after waiting for that number of seconds if input does | |
1987 | not arrive. | |
726f6388 | 1988 | .TP |
1569c106 CR |
1989 | .B TMPDIR |
1990 | If set, \fBBash\fP uses its value as the name of a directory in which | |
1991 | \fBBash\fP creates temporary files for the shell's use. | |
1992 | .TP | |
726f6388 JA |
1993 | .B auto_resume |
1994 | This variable controls how the shell interacts with the user and | |
1995 | job control. If this variable is set, single word simple | |
1996 | commands without redirections are treated as candidates for resumption | |
1997 | of an existing stopped job. There is no ambiguity allowed; if there is | |
1998 | more than one job beginning with the string typed, the job most recently | |
1999 | accessed is selected. The | |
2000 | .I name | |
2001 | of a stopped job, in this context, is the command line used to | |
2002 | start it. | |
2003 | If set to the value | |
2004 | .IR exact , | |
2005 | the string supplied must match the name of a stopped job exactly; | |
2006 | if set to | |
2007 | .IR substring , | |
2008 | the string supplied needs to match a substring of the name of a | |
2009 | stopped job. The | |
2010 | .I substring | |
2011 | value provides functionality analogous to the | |
2012 | .B %? | |
ccc6cda3 | 2013 | job identifier (see |
726f6388 JA |
2014 | .SM |
2015 | .B JOB CONTROL | |
2016 | below). If set to any other value, the supplied string must | |
2017 | be a prefix of a stopped job's name; this provides functionality | |
22e63b05 | 2018 | analogous to the \fB%\fP\fIstring\fP job identifier. |
bb70624e | 2019 | .TP |
f73dda09 JA |
2020 | .B histchars |
2021 | The two or three characters which control history expansion | |
2022 | and tokenization (see | |
2023 | .SM | |
2024 | .B HISTORY EXPANSION | |
2025 | below). The first character is the \fIhistory expansion\fP character, | |
2026 | the character which signals the start of a history | |
2027 | expansion, normally `\fB!\fP'. | |
2028 | The second character is the \fIquick substitution\fP | |
2029 | character, which is used as shorthand for re-running the previous | |
2030 | command entered, substituting one string for another in the command. | |
2031 | The default is `\fB^\fP'. | |
2032 | The optional third character is the character | |
2033 | which indicates that the remainder of the line is a comment when found | |
2034 | as the first character of a word, normally `\fB#\fP'. The history | |
2035 | comment character causes history substitution to be skipped for the | |
2036 | remaining words on the line. It does not necessarily cause the shell | |
2037 | parser to treat the rest of the line as a comment. | |
726f6388 | 2038 | .PD |
ccc6cda3 JA |
2039 | .SS Arrays |
2040 | .B Bash | |
2041 | provides one-dimensional array variables. Any variable may be used as | |
2042 | an array; the | |
2043 | .B declare | |
2044 | builtin will explicitly declare an array. There is no maximum | |
2045 | limit on the size of an array, nor any requirement that members | |
2046 | be indexed or assigned contiguously. Arrays are indexed using | |
2047 | integers and are zero-based. | |
2048 | .PP | |
2049 | An array is created automatically if any variable is assigned to using | |
2050 | the syntax \fIname\fP[\fIsubscript\fP]=\fIvalue\fP. The | |
2051 | .I subscript | |
2052 | is treated as an arithmetic expression that must evaluate to a number | |
2053 | greater than or equal to zero. To explicitly declare an array, use | |
2054 | .B declare \-a \fIname\fP | |
2055 | (see | |
2056 | .SM | |
2057 | .B SHELL BUILTIN COMMANDS | |
2058 | below). | |
2059 | .B declare \-a \fIname\fP[\fIsubscript\fP] | |
2060 | is also accepted; the \fIsubscript\fP is ignored. Attributes may be | |
2061 | specified for an array variable using the | |
2062 | .B declare | |
2063 | and | |
2064 | .B readonly | |
2065 | builtins. Each attribute applies to all members of an array. | |
2066 | .PP | |
2067 | Arrays are assigned to using compound assignments of the form | |
2068 | \fIname\fP=\fB(\fPvalue\fI1\fP ... value\fIn\fP\fB)\fP, where each | |
2069 | \fIvalue\fP is of the form [\fIsubscript\fP]=\fIstring\fP. Only | |
2070 | \fIstring\fP is required. If | |
2071 | the optional brackets and subscript are supplied, that index is assigned to; | |
2072 | otherwise the index of the element assigned is the last index assigned | |
2073 | to by the statement plus one. Indexing starts at zero. | |
2074 | This syntax is also accepted by the | |
2075 | .B declare | |
2076 | builtin. Individual array elements may be assigned to using the | |
2077 | \fIname\fP[\fIsubscript\fP]=\fIvalue\fP syntax introduced above. | |
2078 | .PP | |
2079 | Any element of an array may be referenced using | |
2080 | ${\fIname\fP[\fIsubscript\fP]}. The braces are required to avoid | |
2081 | conflicts with pathname expansion. If | |
2082 | \fIsubscript\fP is \fB@\fP or \fB*\fP, the word expands to | |
2083 | all members of \fIname\fP. These subscripts differ only when the | |
2084 | word appears within double quotes. If the word is double-quoted, | |
2085 | ${\fIname\fP[*]} expands to a single | |
2086 | word with the value of each array member separated by the first | |
2087 | character of the | |
2088 | .SM | |
2089 | .B IFS | |
2090 | special variable, and ${\fIname\fP[@]} expands each element of | |
2091 | \fIname\fP to a separate word. When there are no array members, | |
be7d8f2d CR |
2092 | ${\fIname\fP[@]} expands to nothing. |
2093 | If the double-quoted expansion occurs within a word, the expansion of | |
2094 | the first parameter is joined with the beginning part of the original | |
2095 | word, and the expansion of the last parameter is joined with the last | |
2096 | part of the original word. | |
2097 | This is analogous to the expansion | |
ccc6cda3 JA |
2098 | of the special parameters \fB*\fP and \fB@\fP (see |
2099 | .B Special Parameters | |
2100 | above). ${#\fIname\fP[\fIsubscript\fP]} expands to the length of | |
2101 | ${\fIname\fP[\fIsubscript\fP]}. If \fIsubscript\fP is \fB*\fP or | |
2102 | \fB@\fP, the expansion is the number of elements in the array. | |
2103 | Referencing an array variable without a subscript is equivalent to | |
2104 | referencing element zero. | |
2105 | .PP | |
2106 | The | |
2107 | .B unset | |
bb70624e | 2108 | builtin is used to destroy arrays. \fBunset\fP \fIname\fP[\fIsubscript\fP] |
ccc6cda3 | 2109 | destroys the array element at index \fIsubscript\fP. |
a82a04b3 CR |
2110 | Care must be taken to avoid unwanted side effects caused by filename |
2111 | generation. | |
ccc6cda3 JA |
2112 | \fBunset\fP \fIname\fP, where \fIname\fP is an array, or |
2113 | \fBunset\fP \fIname\fP[\fIsubscript\fP], where | |
2114 | \fIsubscript\fP is \fB*\fP or \fB@\fP, removes the entire array. | |
2115 | .PP | |
2116 | The | |
2117 | .BR declare , | |
2118 | .BR local , | |
2119 | and | |
2120 | .B readonly | |
2121 | builtins each accept a | |
2122 | .B \-a | |
2123 | option to specify an array. The | |
2124 | .B read | |
2125 | builtin accepts a | |
2126 | .B \-a | |
2127 | option to assign a list of words read from the standard input | |
2128 | to an array. The | |
2129 | .B set | |
2130 | and | |
2131 | .B declare | |
2132 | builtins display array values in a way that allows them to be | |
2133 | reused as assignments. | |
726f6388 JA |
2134 | .SH EXPANSION |
2135 | Expansion is performed on the command line after it has been split into | |
2136 | words. There are seven kinds of expansion performed: | |
2137 | .IR "brace expansion" , | |
2138 | .IR "tilde expansion" , | |
2139 | .IR "parameter and variable expansion" , | |
2140 | .IR "command substitution" , | |
2141 | .IR "arithmetic expansion" , | |
2142 | .IR "word splitting" , | |
2143 | and | |
2144 | .IR "pathname expansion" . | |
2145 | .PP | |
2146 | The order of expansions is: brace expansion, tilde expansion, | |
ccc6cda3 JA |
2147 | parameter, variable and arithmetic expansion and |
2148 | command substitution | |
2149 | (done in a left-to-right fashion), word splitting, and pathname | |
726f6388 JA |
2150 | expansion. |
2151 | .PP | |
2152 | On systems that can support it, there is an additional expansion | |
2153 | available: \fIprocess substitution\fP. | |
2154 | .PP | |
2155 | Only brace expansion, word splitting, and pathname expansion | |
2156 | can change the number of words of the expansion; other expansions | |
2157 | expand a single word to a single word. | |
ccc6cda3 | 2158 | The only exceptions to this are the expansions of |
cce855bc | 2159 | "\fB$@\fP" and "\fB${\fP\fIname\fP\fB[@]}\fP" |
ccc6cda3 | 2160 | as explained above (see |
726f6388 JA |
2161 | .SM |
2162 | .BR PARAMETERS ). | |
2163 | .SS Brace Expansion | |
2164 | .PP | |
2165 | .I "Brace expansion" | |
2166 | is a mechanism by which arbitrary strings | |
2167 | may be generated. This mechanism is similar to | |
2168 | \fIpathname expansion\fP, but the filenames generated | |
2169 | need not exist. Patterns to be brace expanded take | |
2170 | the form of an optional | |
2171 | .IR preamble , | |
d3a24ed2 CR |
2172 | followed by either a series of comma-separated strings or |
2173 | a sequence expression between a pair of braces, followed by | |
2174 | an optional | |
cce855bc | 2175 | .IR postscript . |
ccc6cda3 | 2176 | The preamble is prefixed to each string contained |
cce855bc | 2177 | within the braces, and the postscript is then appended |
726f6388 JA |
2178 | to each resulting string, expanding left to right. |
2179 | .PP | |
2180 | Brace expansions may be nested. The results of each expanded | |
2181 | string are not sorted; left to right order is preserved. | |
2182 | For example, a\fB{\fPd,c,b\fB}\fPe expands into `ade ace abe'. | |
2183 | .PP | |
d3a24ed2 CR |
2184 | A sequence expression takes the form \fB{\fP\fIx\fP\fB..\fP\fIy\fP\fB}\fP, |
2185 | where \fIx\fP and \fIy\fP are either integers or single characters. | |
2186 | When integers are supplied, the expression expands to each number between | |
2187 | \fIx\fP and \fIy\fP, inclusive. | |
2188 | When characters are supplied, the expression expands to each character | |
2189 | lexicographically between \fIx\fP and \fIy\fP, inclusive. Note that | |
2190 | both \fIx\fP and \fIy\fP must be of the same type. | |
2191 | .PP | |
726f6388 JA |
2192 | Brace expansion is performed before any other expansions, |
2193 | and any characters special to other expansions are preserved | |
2194 | in the result. It is strictly textual. | |
2195 | .B Bash | |
2196 | does not apply any syntactic interpretation to the context of the | |
2197 | expansion or the text between the braces. | |
2198 | .PP | |
2199 | A correctly-formed brace expansion must contain unquoted opening | |
d3a24ed2 CR |
2200 | and closing braces, and at least one unquoted comma or a valid |
2201 | sequence expression. | |
726f6388 | 2202 | Any incorrectly formed brace expansion is left unchanged. |
ccc6cda3 JA |
2203 | A \fB{\fP or \fB,\fP may be quoted with a backslash to prevent its |
2204 | being considered part of a brace expression. | |
bb70624e JA |
2205 | To avoid conflicts with parameter expansion, the string \fB${\fP |
2206 | is not considered eligible for brace expansion. | |
726f6388 JA |
2207 | .PP |
2208 | This construct is typically used as shorthand when the common | |
2209 | prefix of the strings to be generated is longer than in the | |
2210 | above example: | |
2211 | .RS | |
2212 | .PP | |
2213 | mkdir /usr/local/src/bash/{old,new,dist,bugs} | |
2214 | .RE | |
2215 | or | |
2216 | .RS | |
2217 | chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}} | |
2218 | .RE | |
2219 | .PP | |
2220 | Brace expansion introduces a slight incompatibility with | |
ccc6cda3 JA |
2221 | historical versions of |
2222 | .BR sh . | |
726f6388 JA |
2223 | .B sh |
2224 | does not treat opening or closing braces specially when they | |
2225 | appear as part of a word, and preserves them in the output. | |
2226 | .B Bash | |
2227 | removes braces from words as a consequence of brace | |
2228 | expansion. For example, a word entered to | |
2229 | .B sh | |
2230 | as \fIfile{1,2}\fP | |
2231 | appears identically in the output. The same word is | |
2232 | output as | |
2233 | .I file1 file2 | |
2234 | after expansion by | |
2235 | .BR bash . | |
2236 | If strict compatibility with | |
2237 | .B sh | |
2238 | is desired, start | |
2239 | .B bash | |
2240 | with the | |
ccc6cda3 JA |
2241 | .B +B |
2242 | option or disable brace expansion with the | |
2243 | .B +B | |
726f6388 JA |
2244 | option to the |
2245 | .B set | |
2246 | command (see | |
2247 | .SM | |
2248 | .B SHELL BUILTIN COMMANDS | |
2249 | below). | |
2250 | .SS Tilde Expansion | |
2251 | .PP | |
cce855bc JA |
2252 | If a word begins with an unquoted tilde character (`\fB~\fP'), all of |
2253 | the characters preceding the first unquoted slash (or all characters, | |
2254 | if there is no unquoted slash) are considered a \fItilde-prefix\fP. | |
2255 | If none of the characters in the tilde-prefix are quoted, the | |
2256 | characters in the tilde-prefix following the tilde are treated as a | |
2257 | possible \fIlogin name\fP. | |
2258 | If this login name is the null string, the tilde is replaced with the | |
2259 | value of the shell parameter | |
726f6388 JA |
2260 | .SM |
2261 | .BR HOME . | |
2262 | If | |
2263 | .SM | |
2264 | .B HOME | |
cce855bc JA |
2265 | is unset, the home directory of the user executing the shell is |
2266 | substituted instead. | |
2267 | Otherwise, the tilde-prefix is replaced with the home directory | |
2268 | associated with the specified login name. | |
726f6388 | 2269 | .PP |
cce855bc | 2270 | If the tilde-prefix is a `~+', the value of the shell variable |
726f6388 JA |
2271 | .SM |
2272 | .B PWD | |
cce855bc JA |
2273 | replaces the tilde-prefix. |
2274 | If the tilde-prefix is a `~\-', the value of the shell variable | |
2275 | .SM | |
2276 | .BR OLDPWD , | |
2277 | if it is set, is substituted. | |
2278 | If the characters following the tilde in the tilde-prefix consist | |
2279 | of a number \fIN\fP, optionally prefixed | |
2280 | by a `+' or a `\-', the tilde-prefix is replaced with the corresponding | |
2281 | element from the directory stack, as it would be displayed by the | |
2282 | .B dirs | |
2283 | builtin invoked with the tilde-prefix as an argument. | |
2284 | If the characters following the tilde in the tilde-prefix consist of a | |
2285 | number without a leading `+' or `\-', `+' is assumed. | |
2286 | .PP | |
2287 | If the login name is invalid, or the tilde expansion fails, the word | |
2288 | is unchanged. | |
726f6388 | 2289 | .PP |
cce855bc JA |
2290 | Each variable assignment is checked for unquoted tilde-prefixes immediately |
2291 | following a | |
726f6388 | 2292 | .B : |
43df7bbb | 2293 | or the first |
726f6388 | 2294 | .BR = . |
cce855bc JA |
2295 | In these cases, tilde expansion is also performed. |
2296 | Consequently, one may use file names with tildes in assignments to | |
726f6388 JA |
2297 | .SM |
2298 | .BR PATH , | |
2299 | .SM | |
2300 | .BR MAILPATH , | |
2301 | and | |
2302 | .SM | |
2303 | .BR CDPATH , | |
2304 | and the shell assigns the expanded value. | |
2305 | .SS Parameter Expansion | |
2306 | .PP | |
2307 | The `\fB$\fP' character introduces parameter expansion, | |
2308 | command substitution, or arithmetic expansion. The parameter name | |
2309 | or symbol to be expanded may be enclosed in braces, which | |
2310 | are optional but serve to protect the variable to be expanded from | |
2311 | characters immediately following it which could be | |
2312 | interpreted as part of the name. | |
2313 | .PP | |
cce855bc JA |
2314 | When braces are used, the matching ending brace is the first `\fB}\fP' |
2315 | not escaped by a backslash or within a quoted string, and not within an | |
f75912ae | 2316 | embedded arithmetic expansion, command substitution, or parameter |
cce855bc JA |
2317 | expansion. |
2318 | .PP | |
726f6388 JA |
2319 | .PD 0 |
2320 | .TP | |
2321 | ${\fIparameter\fP} | |
2322 | The value of \fIparameter\fP is substituted. The braces are required | |
2323 | when | |
2324 | .I parameter | |
2325 | is a positional parameter with more than one digit, | |
2326 | or when | |
2327 | .I parameter | |
2328 | is followed by a character which is not to be | |
2329 | interpreted as part of its name. | |
2330 | .PD | |
2331 | .PP | |
ccc6cda3 JA |
2332 | If the first character of \fIparameter\fP is an exclamation point, |
2333 | a level of variable indirection is introduced. | |
2334 | \fBBash\fP uses the value of the variable formed from the rest of | |
2335 | \fIparameter\fP as the name of the variable; this variable is then | |
bb70624e | 2336 | expanded and that value is used in the rest of the substitution, rather |
ccc6cda3 JA |
2337 | than the value of \fIparameter\fP itself. |
2338 | This is known as \fIindirect expansion\fP. | |
d3a24ed2 CR |
2339 | The exceptions to this are the expansions of ${!\fIprefix\fP*} and |
2340 | ${\fB!\fP\fIname\fP[\fI@\fP]} described below. | |
2341 | The exclamation point must immediately follow the left brace in order to | |
2342 | introduce indirection. | |
ccc6cda3 | 2343 | .PP |
726f6388 JA |
2344 | In each of the cases below, \fIword\fP is subject to tilde expansion, |
2345 | parameter expansion, command substitution, and arithmetic expansion. | |
ccc6cda3 JA |
2346 | When not performing substring expansion, \fBbash\fP tests for a parameter |
2347 | that is unset or null; omitting the colon results in a test only for a | |
2348 | parameter that is unset. | |
726f6388 JA |
2349 | .PP |
2350 | .PD 0 | |
2351 | .TP | |
2352 | ${\fIparameter\fP\fB:\-\fP\fIword\fP} | |
2353 | \fBUse Default Values\fP. If | |
2354 | .I parameter | |
2355 | is unset or null, the expansion of | |
2356 | .I word | |
2357 | is substituted. Otherwise, the value of | |
2358 | .I parameter | |
2359 | is substituted. | |
2360 | .TP | |
2361 | ${\fIparameter\fP\fB:=\fP\fIword\fP} | |
2362 | \fBAssign Default Values\fP. | |
2363 | If | |
2364 | .I parameter | |
2365 | is unset or null, the expansion of | |
2366 | .I word | |
2367 | is assigned to | |
2368 | .IR parameter . | |
2369 | The value of | |
2370 | .I parameter | |
2371 | is then substituted. Positional parameters and special parameters may | |
2372 | not be assigned to in this way. | |
2373 | .TP | |
2374 | ${\fIparameter\fP\fB:?\fP\fIword\fP} | |
2375 | \fBDisplay Error if Null or Unset\fP. | |
2376 | If | |
2377 | .I parameter | |
2378 | is null or unset, the expansion of \fIword\fP (or a message to that effect | |
2379 | if | |
2380 | .I word | |
2381 | is not present) is written to the standard error and the shell, if it | |
2382 | is not interactive, exits. Otherwise, the value of \fIparameter\fP is | |
2383 | substituted. | |
2384 | .TP | |
2385 | ${\fIparameter\fP\fB:+\fP\fIword\fP} | |
2386 | \fBUse Alternate Value\fP. | |
2387 | If | |
2388 | .I parameter | |
2389 | is null or unset, nothing is substituted, otherwise the expansion of | |
2390 | .I word | |
2391 | is substituted. | |
2392 | .TP | |
ccc6cda3 | 2393 | ${\fIparameter\fP\fB:\fP\fIoffset\fP} |
7117c2d2 | 2394 | .PD 0 |
ccc6cda3 JA |
2395 | .TP |
2396 | ${\fIparameter\fP\fB:\fP\fIoffset\fP\fB:\fP\fIlength\fP} | |
2397 | .PD | |
2398 | \fBSubstring Expansion.\fP | |
bb70624e JA |
2399 | Expands to up to \fIlength\fP characters of \fIparameter\fP |
2400 | starting at the character specified by \fIoffset\fP. | |
ccc6cda3 | 2401 | If \fIlength\fP is omitted, expands to the substring of |
bb70624e | 2402 | \fIparameter\fP starting at the character specified by \fIoffset\fP. |
ccc6cda3 JA |
2403 | \fIlength\fP and \fIoffset\fP are arithmetic expressions (see |
2404 | .SM | |
2405 | .B | |
2406 | ARITHMETIC EVALUATION | |
2407 | below). | |
2408 | \fIlength\fP must evaluate to a number greater than or equal to zero. | |
2409 | If \fIoffset\fP evaluates to a number less than zero, the value | |
2410 | is used as an offset from the end of the value of \fIparameter\fP. | |
2411 | If \fIparameter\fP is \fB@\fP, the result is \fIlength\fP positional | |
2412 | parameters beginning at \fIoffset\fP. | |
2413 | If \fIparameter\fP is an array name indexed by @ or *, | |
2414 | the result is the \fIlength\fP | |
2415 | members of the array beginning with ${\fIparameter\fP[\fIoffset\fP]}. | |
ec2199bd CR |
2416 | A negative \fIoffset\fP is taken relative to one greater than the maximum |
2417 | index of the specified array. | |
2418 | Note that a negative offset must be separated from the colon by at least | |
2419 | one space to avoid being confused with the :- expansion. | |
cce855bc JA |
2420 | Substring indexing is zero-based unless the positional parameters |
2421 | are used, in which case the indexing starts at 1. | |
ccc6cda3 | 2422 | .TP |
bb70624e | 2423 | ${\fB!\fP\fIprefix\fP\fB*\fP} |
d3a24ed2 CR |
2424 | .PD 0 |
2425 | .TP | |
2426 | ${\fB!\fP\fIprefix\fP\fB@\fP} | |
2427 | .PD | |
bb70624e JA |
2428 | Expands to the names of variables whose names begin with \fIprefix\fP, |
2429 | separated by the first character of the | |
2430 | .SM | |
2431 | .B IFS | |
2432 | special variable. | |
2433 | .TP | |
d3a24ed2 CR |
2434 | ${\fB!\fP\fIname\fP[\fI@\fP]} |
2435 | .PD 0 | |
2436 | .TP | |
2437 | ${\fB!\fP\fIname\fP[\fI*\fP]} | |
2438 | .PD | |
2439 | If \fIname\fP is an array variable, expands to the list of array indices | |
2440 | (keys) assigned in \fIname\fP. | |
2441 | If \fIname\fP is not an array, expands to 0 if \fIname\fP is set and null | |
2442 | otherwise. | |
2443 | When \fI@\fP is used and the expansion appears within double quotes, each | |
2444 | key expands to a separate word. | |
2445 | .TP | |
726f6388 JA |
2446 | ${\fB#\fP\fIparameter\fP} |
2447 | The length in characters of the value of \fIparameter\fP is substituted. | |
ccc6cda3 JA |
2448 | If |
2449 | .I parameter | |
2450 | is | |
726f6388 JA |
2451 | .B * |
2452 | or | |
2453 | .BR @ , | |
cce855bc | 2454 | the value substituted is the number of positional parameters. |
ccc6cda3 JA |
2455 | If |
2456 | .I parameter | |
2457 | is an array name subscripted by | |
726f6388 | 2458 | .B * |
ccc6cda3 JA |
2459 | or |
2460 | .BR @ , | |
cce855bc | 2461 | the value substituted is the number of elements in the array. |
726f6388 | 2462 | .TP |
726f6388 | 2463 | ${\fIparameter\fP\fB#\fP\fIword\fP} |
7117c2d2 | 2464 | .PD 0 |
726f6388 JA |
2465 | .TP |
2466 | ${\fIparameter\fP\fB##\fP\fIword\fP} | |
2467 | .PD | |
2468 | The | |
2469 | .I word | |
2470 | is expanded to produce a pattern just as in pathname | |
2471 | expansion. If the pattern matches the beginning of | |
2472 | the value of | |
2473 | .IR parameter , | |
cce855bc | 2474 | then the result of the expansion is the expanded value of |
726f6388 | 2475 | .I parameter |
ccc6cda3 JA |
2476 | with the shortest matching pattern (the ``\fB#\fP'' case) or the |
2477 | longest matching pattern (the ``\fB##\fP'' case) deleted. | |
2478 | If | |
2479 | .I parameter | |
2480 | is | |
2481 | .B @ | |
2482 | or | |
2483 | .BR * , | |
2484 | the pattern removal operation is applied to each positional | |
2485 | parameter in turn, and the expansion is the resultant list. | |
2486 | If | |
2487 | .I parameter | |
2488 | is an array variable subscripted with | |
2489 | .B @ | |
2490 | or | |
2491 | .BR * , | |
2492 | the pattern removal operation is applied to each member of the | |
2493 | array in turn, and the expansion is the resultant list. | |
726f6388 | 2494 | .TP |
726f6388 | 2495 | ${\fIparameter\fP\fB%\fP\fIword\fP} |
7117c2d2 | 2496 | .PD 0 |
726f6388 JA |
2497 | .TP |
2498 | ${\fIparameter\fP\fB%%\fP\fIword\fP} | |
2499 | .PD | |
2500 | The \fIword\fP is expanded to produce a pattern just as in | |
ccc6cda3 | 2501 | pathname expansion. |
cce855bc | 2502 | If the pattern matches a trailing portion of the expanded value of |
726f6388 | 2503 | .IR parameter , |
cce855bc | 2504 | then the result of the expansion is the expanded value of |
726f6388 | 2505 | .I parameter |
ccc6cda3 JA |
2506 | with the shortest matching pattern (the ``\fB%\fP'' case) or the |
2507 | longest matching pattern (the ``\fB%%\fP'' case) deleted. | |
2508 | If | |
2509 | .I parameter | |
2510 | is | |
2511 | .B @ | |
2512 | or | |
2513 | .BR * , | |
2514 | the pattern removal operation is applied to each positional | |
2515 | parameter in turn, and the expansion is the resultant list. | |
2516 | If | |
2517 | .I parameter | |
2518 | is an array variable subscripted with | |
2519 | .B @ | |
2520 | or | |
2521 | .BR * , | |
2522 | the pattern removal operation is applied to each member of the | |
2523 | array in turn, and the expansion is the resultant list. | |
2524 | .TP | |
ccc6cda3 | 2525 | ${\fIparameter\fP\fB/\fP\fIpattern\fP\fB/\fP\fIstring\fP} |
7117c2d2 | 2526 | .PD 0 |
ccc6cda3 JA |
2527 | .TP |
2528 | ${\fIparameter\fP\fB//\fP\fIpattern\fP\fB/\fP\fIstring\fP} | |
2529 | .PD | |
2530 | The \fIpattern\fP is expanded to produce a pattern just as in | |
2531 | pathname expansion. | |
2532 | \fIParameter\fP is expanded and the longest match of \fIpattern\fP | |
2533 | against its value is replaced with \fIstring\fP. | |
2534 | In the first form, only the first match is replaced. | |
2535 | The second form causes all matches of \fIpattern\fP to be | |
2536 | replaced with \fIstring\fP. | |
2537 | If \fIpattern\fP begins with \fB#\fP, it must match at the beginning | |
b72432fd | 2538 | of the expanded value of \fIparameter\fP. |
ccc6cda3 | 2539 | If \fIpattern\fP begins with \fB%\fP, it must match at the end |
b72432fd | 2540 | of the expanded value of \fIparameter\fP. |
ccc6cda3 JA |
2541 | If \fIstring\fP is null, matches of \fIpattern\fP are deleted |
2542 | and the \fB/\fP following \fIpattern\fP may be omitted. | |
2543 | If | |
2544 | .I parameter | |
2545 | is | |
2546 | .B @ | |
2547 | or | |
2548 | .BR * , | |
2549 | the substitution operation is applied to each positional | |
2550 | parameter in turn, and the expansion is the resultant list. | |
2551 | If | |
2552 | .I parameter | |
2553 | is an array variable subscripted with | |
2554 | .B @ | |
2555 | or | |
2556 | .BR * , | |
2557 | the substitution operation is applied to each member of the | |
2558 | array in turn, and the expansion is the resultant list. | |
726f6388 JA |
2559 | .SS Command Substitution |
2560 | .PP | |
cce855bc | 2561 | \fICommand substitution\fP allows the output of a command to replace |
726f6388 JA |
2562 | the command name. There are two forms: |
2563 | .PP | |
2564 | .RS | |
2565 | .PP | |
2566 | \fB$(\fP\fIcommand\fP\|\fB)\fP | |
2567 | .RE | |
2568 | or | |
2569 | .RS | |
2570 | \fB`\fP\fIcommand\fP\fB`\fP | |
2571 | .RE | |
2572 | .PP | |
ccc6cda3 | 2573 | .B Bash |
726f6388 JA |
2574 | performs the expansion by executing \fIcommand\fP and |
2575 | replacing the command substitution with the standard output of the | |
2576 | command, with any trailing newlines deleted. | |
cce855bc JA |
2577 | Embedded newlines are not deleted, but they may be removed during |
2578 | word splitting. | |
2579 | The command substitution \fB$(cat \fIfile\fP)\fR can be replaced by | |
2580 | the equivalent but faster \fB$(< \fIfile\fP)\fR. | |
726f6388 | 2581 | .PP |
ccc6cda3 | 2582 | When the old-style backquote form of substitution is used, |
726f6388 JA |
2583 | backslash retains its literal meaning except when followed by |
2584 | .BR $ , | |
2585 | .BR ` , | |
2586 | or | |
2587 | .BR \e . | |
cce855bc JA |
2588 | The first backquote not preceded by a backslash terminates the |
2589 | command substitution. | |
726f6388 JA |
2590 | When using the $(\^\fIcommand\fP\|) form, all characters between the |
2591 | parentheses make up the command; none are treated specially. | |
2592 | .PP | |
cce855bc | 2593 | Command substitutions may be nested. To nest when using the backquoted form, |
726f6388 JA |
2594 | escape the inner backquotes with backslashes. |
2595 | .PP | |
2596 | If the substitution appears within double quotes, word splitting and | |
2597 | pathname expansion are not performed on the results. | |
2598 | .SS Arithmetic Expansion | |
2599 | .PP | |
2600 | Arithmetic expansion allows the evaluation of an arithmetic expression | |
ccc6cda3 | 2601 | and the substitution of the result. The format for arithmetic expansion is: |
726f6388 JA |
2602 | .RS |
2603 | .PP | |
726f6388 JA |
2604 | \fB$((\fP\fIexpression\fP\fB))\fP |
2605 | .RE | |
2606 | .PP | |
2607 | The | |
2608 | .I expression | |
2609 | is treated as if it were within double quotes, but a double quote | |
ccc6cda3 JA |
2610 | inside the parentheses is not treated specially. |
2611 | All tokens in the expression undergo parameter expansion, string | |
2612 | expansion, command substitution, and quote removal. | |
d3a24ed2 | 2613 | Arithmetic expansions may be nested. |
726f6388 JA |
2614 | .PP |
2615 | The evaluation is performed according to the rules listed below under | |
2616 | .SM | |
2617 | .BR "ARITHMETIC EVALUATION" . | |
2618 | If | |
2619 | .I expression | |
2620 | is invalid, | |
2621 | .B bash | |
2622 | prints a message indicating failure and no substitution occurs. | |
2623 | .SS Process Substitution | |
2624 | .PP | |
2625 | \fIProcess substitution\fP is supported on systems that support named | |
2626 | pipes (\fIFIFOs\fP) or the \fB/dev/fd\fP method of naming open files. | |
2627 | It takes the form of | |
2628 | \fB<(\fP\fIlist\^\fP\fB)\fP | |
2629 | or | |
2630 | \fB>(\fP\fIlist\^\fP\fB)\fP. | |
2631 | The process \fIlist\fP is run with its input or output connected to a | |
2632 | \fIFIFO\fP or some file in \fB/dev/fd\fP. The name of this file is | |
2633 | passed as an argument to the current command as the result of the | |
2634 | expansion. If the \fB>(\fP\fIlist\^\fP\fB)\fP form is used, writing to | |
2635 | the file will provide input for \fIlist\fP. If the | |
2636 | \fB<(\fP\fIlist\^\fP\fB)\fP form is used, the file passed as an | |
2637 | argument should be read to obtain the output of \fIlist\fP. | |
2638 | .PP | |
bb70624e | 2639 | When available, process substitution is performed |
ccc6cda3 JA |
2640 | simultaneously with parameter and variable expansion, |
2641 | command substitution, | |
2642 | and arithmetic expansion. | |
726f6388 JA |
2643 | .SS Word Splitting |
2644 | .PP | |
2645 | The shell scans the results of | |
2646 | parameter expansion, | |
2647 | command substitution, | |
2648 | and | |
2649 | arithmetic expansion | |
2650 | that did not occur within double quotes for | |
2651 | .IR "word splitting" . | |
2652 | .PP | |
2653 | The shell treats each character of | |
2654 | .SM | |
2655 | .B IFS | |
2656 | as a delimiter, and splits the results of the other | |
ccc6cda3 | 2657 | expansions into words on these characters. If |
726f6388 JA |
2658 | .SM |
2659 | .B IFS | |
ccc6cda3 JA |
2660 | is unset, or its |
2661 | value is exactly | |
726f6388 JA |
2662 | .BR <space><tab><newline> , |
2663 | the default, then | |
2664 | any sequence of | |
2665 | .SM | |
2666 | .B IFS | |
2667 | characters serves to delimit words. If | |
2668 | .SM | |
2669 | .B IFS | |
2670 | has a value other than the default, then sequences of | |
2671 | the whitespace characters | |
2672 | .B space | |
2673 | and | |
2674 | .B tab | |
2675 | are ignored at the beginning and end of the | |
2676 | word, as long as the whitespace character is in the | |
2677 | value of | |
2678 | .SM | |
2679 | .BR IFS | |
2680 | (an | |
2681 | .SM | |
2682 | .B IFS | |
2683 | whitespace character). | |
2684 | Any character in | |
2685 | .SM | |
2686 | .B IFS | |
2687 | that is not | |
2688 | .SM | |
2689 | .B IFS | |
2690 | whitespace, along with any adjacent | |
2691 | .SM | |
2692 | .B IFS | |
2693 | whitespace characters, delimits a field. | |
2694 | A sequence of | |
2695 | .SM | |
2696 | .B IFS | |
2697 | whitespace characters is also treated as a delimiter. | |
2698 | If the value of | |
2699 | .SM | |
2700 | .B IFS | |
2701 | is null, no word splitting occurs. | |
726f6388 | 2702 | .PP |
ccc6cda3 JA |
2703 | Explicit null arguments (\^\f3"\^"\fP or \^\f3'\^'\fP\^) are retained. |
2704 | Unquoted implicit null arguments, resulting from the expansion of | |
bb70624e | 2705 | parameters that have no values, are removed. |
ccc6cda3 JA |
2706 | If a parameter with no value is expanded within double quotes, a |
2707 | null argument results and is retained. | |
726f6388 JA |
2708 | .PP |
2709 | Note that if no expansion occurs, no splitting | |
2710 | is performed. | |
2711 | .SS Pathname Expansion | |
2712 | .PP | |
2713 | After word splitting, | |
2714 | unless the | |
2715 | .B \-f | |
2716 | option has been set, | |
2717 | .B bash | |
ccc6cda3 | 2718 | scans each word for the characters |
726f6388 JA |
2719 | .BR * , |
2720 | .BR ? , | |
2721 | and | |
2722 | .BR [ . | |
2723 | If one of these characters appears, then the word is | |
2724 | regarded as a | |
2725 | .IR pattern , | |
2726 | and replaced with an alphabetically sorted list of | |
ccc6cda3 JA |
2727 | file names matching the pattern. |
2728 | If no matching file names are found, | |
2729 | and the shell option | |
2730 | .B nullglob | |
2731 | is disabled, the word is left unchanged. | |
cce855bc JA |
2732 | If the |
2733 | .B nullglob | |
2734 | option is set, and no matches are found, | |
726f6388 | 2735 | the word is removed. |
d3a24ed2 CR |
2736 | If the |
2737 | .B failglob | |
2738 | shell option is set, and no matches are found, an error message | |
2739 | is printed and the command is not executed. | |
cce855bc JA |
2740 | If the shell option |
2741 | .B nocaseglob | |
2742 | is enabled, the match is performed without regard to the case | |
2743 | of alphabetic characters. | |
ccc6cda3 | 2744 | When a pattern is used for pathname expansion, |
726f6388 JA |
2745 | the character |
2746 | .B ``.'' | |
2747 | at the start of a name or immediately following a slash | |
ccc6cda3 JA |
2748 | must be matched explicitly, unless the shell option |
2749 | .B dotglob | |
2750 | is set. | |
cce855bc JA |
2751 | When matching a pathname, the slash character must always be |
2752 | matched explicitly. | |
ccc6cda3 | 2753 | In other cases, the |
726f6388 JA |
2754 | .B ``.'' |
2755 | character is not treated specially. | |
ccc6cda3 JA |
2756 | See the description of |
2757 | .B shopt | |
2758 | below under | |
2759 | .SM | |
2760 | .B SHELL BUILTIN COMMANDS | |
2761 | for a description of the | |
cce855bc JA |
2762 | .BR nocaseglob , |
2763 | .BR nullglob , | |
d3a24ed2 | 2764 | .BR failglob , |
ccc6cda3 JA |
2765 | and |
2766 | .B dotglob | |
2767 | shell options. | |
2768 | .PP | |
2769 | The | |
2770 | .SM | |
2771 | .B GLOBIGNORE | |
2772 | shell variable may be used to restrict the set of file names matching a | |
2773 | .IR pattern . | |
2774 | If | |
2775 | .SM | |
2776 | .B GLOBIGNORE | |
2777 | is set, each matching file name that also matches one of the patterns in | |
2778 | .SM | |
2779 | .B GLOBIGNORE | |
2780 | is removed from the list of matches. | |
2781 | The file names | |
2782 | .B ``.'' | |
2783 | and | |
2784 | .B ``..'' | |
d3a24ed2 | 2785 | are always ignored when |
ccc6cda3 JA |
2786 | .SM |
2787 | .B GLOBIGNORE | |
d3a24ed2 | 2788 | is set and not null. However, setting |
ccc6cda3 JA |
2789 | .SM |
2790 | .B GLOBIGNORE | |
d3a24ed2 | 2791 | to a non-null value has the effect of enabling the |
ccc6cda3 JA |
2792 | .B dotglob |
2793 | shell option, so all other file names beginning with a | |
2794 | .B ``.'' | |
2795 | will match. | |
2796 | To get the old behavior of ignoring file names beginning with a | |
2797 | .BR ``.'' , | |
2798 | make | |
2799 | .B ``.*'' | |
2800 | one of the patterns in | |
2801 | .SM | |
2802 | .BR GLOBIGNORE . | |
2803 | The | |
2804 | .B dotglob | |
2805 | option is disabled when | |
2806 | .SM | |
2807 | .B GLOBIGNORE | |
2808 | is unset. | |
726f6388 | 2809 | .PP |
cce855bc JA |
2810 | \fBPattern Matching\fP |
2811 | .PP | |
2812 | Any character that appears in a pattern, other than the special pattern | |
2813 | characters described below, matches itself. The NUL character may not | |
d3a24ed2 CR |
2814 | occur in a pattern. A backslash escapes the following character; the |
2815 | escaping backslash is discarded when matching. | |
2816 | The special pattern characters must be quoted if | |
cce855bc JA |
2817 | they are to be matched literally. |
2818 | .PP | |
726f6388 JA |
2819 | The special pattern characters have the following meanings: |
2820 | .PP | |
2821 | .PD 0 | |
2822 | .TP | |
2823 | .B * | |
2824 | Matches any string, including the null string. | |
2825 | .TP | |
2826 | .B ? | |
2827 | Matches any single character. | |
2828 | .TP | |
2829 | .B [...] | |
2830 | Matches any one of the enclosed characters. A pair of characters | |
28ef6c31 JA |
2831 | separated by a hyphen denotes a |
2832 | \fIrange expression\fP; | |
2833 | any character that sorts between those two characters, inclusive, | |
2834 | using the current locale's collating sequence and character set, | |
726f6388 JA |
2835 | is matched. If the first character following the |
2836 | .B [ | |
2837 | is a | |
2838 | .B ! | |
2839 | or a | |
2840 | .B ^ | |
ccc6cda3 | 2841 | then any character not enclosed is matched. |
28ef6c31 JA |
2842 | The sorting order of characters in range expressions is determined by |
2843 | the current locale and the value of the \fBLC_COLLATE\fP shell variable, | |
2844 | if set. | |
ccc6cda3 | 2845 | A |
726f6388 | 2846 | .B \- |
726f6388 JA |
2847 | may be matched by including it as the first or last character |
2848 | in the set. | |
ccc6cda3 JA |
2849 | A |
2850 | .B ] | |
2851 | may be matched by including it as the first character | |
2852 | in the set. | |
cce855bc JA |
2853 | .br |
2854 | .if t .sp 0.5 | |
2855 | .if n .sp 1 | |
2856 | Within | |
2857 | .B [ | |
2858 | and | |
2859 | .BR ] , | |
2860 | \fIcharacter classes\fP can be specified using the syntax | |
2861 | \fB[:\fP\fIclass\fP\fB:]\fP, where \fIclass\fP is one of the | |
2862 | following classes defined in the POSIX.2 standard: | |
2863 | .PP | |
2864 | .RS | |
2865 | .B | |
7117c2d2 JA |
2866 | .if n alnum alpha ascii blank cntrl digit graph lower print punct space upper word xdigit |
2867 | .if t alnum alpha ascii blank cntrl digit graph lower print punct space upper word xdigit | |
cce855bc JA |
2868 | .br |
2869 | A character class matches any character belonging to that class. | |
7117c2d2 | 2870 | The \fBword\fP character class matches letters, digits, and the character _. |
cce855bc JA |
2871 | .br |
2872 | .if t .sp 0.5 | |
2873 | .if n .sp 1 | |
2874 | Within | |
2875 | .B [ | |
2876 | and | |
2877 | .BR ] , | |
2878 | an \fIequivalence class\fP can be specified using the syntax | |
2879 | \fB[=\fP\fIc\fP\fB=]\fP, which matches all characters with the | |
2880 | same collation weight (as defined by the current locale) as | |
2881 | the character \fIc\fP. | |
2882 | .br | |
2883 | .if t .sp 0.5 | |
2884 | .if n .sp 1 | |
2885 | Within | |
2886 | .B [ | |
2887 | and | |
2888 | .BR ] , | |
2889 | the syntax \fB[.\fP\fIsymbol\fP\fB.]\fP matches the collating symbol | |
2890 | \fIsymbol\fP. | |
2891 | .RE | |
2892 | .PD | |
2893 | .PP | |
2894 | If the \fBextglob\fP shell option is enabled using the \fBshopt\fP | |
2895 | builtin, several extended pattern matching operators are recognized. | |
bb70624e | 2896 | In the following description, a \fIpattern-list\fP is a list of one |
cce855bc JA |
2897 | or more patterns separated by a \fB|\fP. |
2898 | Composite patterns may be formed using one or more of the following | |
2899 | sub-patterns: | |
2900 | .sp 1 | |
2901 | .PD 0 | |
2902 | .RS | |
2903 | .TP | |
2904 | \fB?(\fP\^\fIpattern-list\^\fP\fB)\fP | |
2905 | Matches zero or one occurrence of the given patterns | |
2906 | .TP | |
2907 | \fB*(\fP\^\fIpattern-list\^\fP\fB)\fP | |
2908 | Matches zero or more occurrences of the given patterns | |
2909 | .TP | |
2910 | \fB+(\fP\^\fIpattern-list\^\fP\fB)\fP | |
2911 | Matches one or more occurrences of the given patterns | |
2912 | .TP | |
2913 | \fB@(\fP\^\fIpattern-list\^\fP\fB)\fP | |
43df7bbb | 2914 | Matches one of the given patterns |
cce855bc JA |
2915 | .TP |
2916 | \fB!(\fP\^\fIpattern-list\^\fP\fB)\fP | |
2917 | Matches anything except one of the given patterns | |
2918 | .RE | |
726f6388 JA |
2919 | .PD |
2920 | .SS Quote Removal | |
2921 | .PP | |
2922 | After the preceding expansions, all unquoted occurrences of the | |
2923 | characters | |
2924 | .BR \e , | |
cce855bc | 2925 | .BR ' , |
ccc6cda3 JA |
2926 | and \^\f3"\fP\^ that did not result from one of the above |
2927 | expansions are removed. | |
726f6388 JA |
2928 | .SH REDIRECTION |
2929 | Before a command is executed, its input and output | |
2930 | may be | |
2931 | .I redirected | |
2932 | using a special notation interpreted by the shell. | |
2933 | Redirection may also be used to open and close files for the | |
2934 | current shell execution environment. The following redirection | |
2935 | operators may precede or appear anywhere within a | |
2936 | .I simple command | |
2937 | or may follow a | |
2938 | .IR command . | |
2939 | Redirections are processed in the order they appear, from | |
2940 | left to right. | |
2941 | .PP | |
2942 | In the following descriptions, if the file descriptor number is | |
2943 | omitted, and the first character of the redirection operator is | |
2944 | .BR < , | |
2945 | the redirection refers to the standard input (file descriptor | |
2946 | 0). If the first character of the redirection operator is | |
2947 | .BR > , | |
2948 | the redirection refers to the standard output (file descriptor | |
2949 | 1). | |
2950 | .PP | |
cce855bc JA |
2951 | The word following the redirection operator in the following |
2952 | descriptions, unless otherwise noted, is subjected to brace expansion, | |
2953 | tilde expansion, parameter expansion, command substitution, arithmetic | |
bb70624e | 2954 | expansion, quote removal, pathname expansion, and word splitting. |
cce855bc | 2955 | If it expands to more than one word, |
726f6388 JA |
2956 | .B bash |
2957 | reports an error. | |
2958 | .PP | |
2959 | Note that the order of redirections is significant. For example, | |
2960 | the command | |
2961 | .RS | |
2962 | .PP | |
2963 | ls \fB>\fP dirlist 2\fB>&\fP1 | |
2964 | .RE | |
2965 | .PP | |
2966 | directs both standard output and standard error to the file | |
2967 | .IR dirlist , | |
2968 | while the command | |
2969 | .RS | |
2970 | .PP | |
2971 | ls 2\fB>&\fP1 \fB>\fP dirlist | |
2972 | .RE | |
2973 | .PP | |
2974 | directs only the standard output to file | |
2975 | .IR dirlist , | |
2976 | because the standard error was duplicated as standard output | |
2977 | before the standard output was redirected to | |
2978 | .IR dirlist . | |
cce855bc | 2979 | .PP |
bb70624e JA |
2980 | \fBBash\fP handles several filenames specially when they are used in |
2981 | redirections, as described in the following table: | |
2982 | .RS | |
2983 | .PP | |
2984 | .PD 0 | |
2985 | .TP | |
2986 | .B /dev/fd/\fIfd\fP | |
2987 | If \fIfd\fP is a valid integer, file descriptor \fIfd\fP is duplicated. | |
2988 | .TP | |
2989 | .B /dev/stdin | |
2990 | File descriptor 0 is duplicated. | |
2991 | .TP | |
2992 | .B /dev/stdout | |
2993 | File descriptor 1 is duplicated. | |
2994 | .TP | |
2995 | .B /dev/stderr | |
2996 | File descriptor 2 is duplicated. | |
2997 | .TP | |
2998 | .B /dev/tcp/\fIhost\fP/\fIport\fP | |
2999 | If \fIhost\fP is a valid hostname or Internet address, and \fIport\fP | |
f73dda09 JA |
3000 | is an integer port number or service name, \fBbash\fP attempts to open |
3001 | a TCP connection to the corresponding socket. | |
bb70624e JA |
3002 | .TP |
3003 | .B /dev/udp/\fIhost\fP/\fIport\fP | |
3004 | If \fIhost\fP is a valid hostname or Internet address, and \fIport\fP | |
f73dda09 JA |
3005 | is an integer port number or service name, \fBbash\fP attempts to open |
3006 | a UDP connection to the corresponding socket. | |
bb70624e JA |
3007 | .PD |
3008 | .RE | |
3009 | .PP | |
cce855bc | 3010 | A failure to open or create a file causes the redirection to fail. |
cac4cdbf CR |
3011 | .PP |
3012 | Redirections using file descriptors greater than 9 should be used with | |
3013 | care, as they may conflict with file descriptors the shell uses | |
3014 | internally. | |
726f6388 JA |
3015 | .SS Redirecting Input |
3016 | .PP | |
3017 | Redirection of input causes the file whose name results from | |
3018 | the expansion of | |
3019 | .I word | |
3020 | to be opened for reading on file descriptor | |
3021 | .IR n , | |
3022 | or the standard input (file descriptor 0) if | |
3023 | .I n | |
3024 | is not specified. | |
3025 | .PP | |
3026 | The general format for redirecting input is: | |
3027 | .RS | |
3028 | .PP | |
3029 | [\fIn\fP]\fB<\fP\fIword\fP | |
3030 | .RE | |
3031 | .SS Redirecting Output | |
3032 | .PP | |
3033 | Redirection of output causes the file whose name results from | |
3034 | the expansion of | |
3035 | .I word | |
3036 | to be opened for writing on file descriptor | |
3037 | .IR n , | |
3038 | or the standard output (file descriptor 1) if | |
3039 | .I n | |
3040 | is not specified. If the file does not exist it is created; | |
3041 | if it does exist it is truncated to zero size. | |
3042 | .PP | |
3043 | The general format for redirecting output is: | |
3044 | .RS | |
3045 | .PP | |
3046 | [\fIn\fP]\fB>\fP\fIword\fP | |
3047 | .RE | |
3048 | .PP | |
3049 | If the redirection operator is | |
ccc6cda3 JA |
3050 | .BR > , |
3051 | and the | |
cce855bc | 3052 | .B noclobber |
ccc6cda3 JA |
3053 | option to the |
3054 | .B set | |
bb70624e | 3055 | builtin has been enabled, the redirection will fail if the file |
cce855bc JA |
3056 | whose name results from the expansion of \fIword\fP exists and is |
3057 | a regular file. | |
ccc6cda3 | 3058 | If the redirection operator is |
726f6388 | 3059 | .BR >| , |
cce855bc JA |
3060 | or the redirection operator is |
3061 | .B > | |
3062 | and the | |
3063 | .B noclobber | |
726f6388 JA |
3064 | option to the |
3065 | .B set | |
cce855bc | 3066 | builtin command is not enabled, the redirection is attempted even |
ccc6cda3 | 3067 | if the file named by \fIword\fP exists. |
726f6388 JA |
3068 | .SS Appending Redirected Output |
3069 | .PP | |
3070 | Redirection of output in this fashion | |
3071 | causes the file whose name results from | |
3072 | the expansion of | |
3073 | .I word | |
3074 | to be opened for appending on file descriptor | |
3075 | .IR n , | |
3076 | or the standard output (file descriptor 1) if | |
3077 | .I n | |
3078 | is not specified. If the file does not exist it is created. | |
3079 | .PP | |
3080 | The general format for appending output is: | |
3081 | .RS | |
3082 | .PP | |
3083 | [\fIn\fP]\fB>>\fP\fIword\fP | |
3084 | .RE | |
3085 | .PP | |
3086 | .SS Redirecting Standard Output and Standard Error | |
3087 | .PP | |
3088 | .B Bash | |
3089 | allows both the | |
3090 | standard output (file descriptor 1) and | |
3091 | the standard error output (file descriptor 2) | |
3092 | to be redirected to the file whose name is the | |
3093 | expansion of | |
3094 | .I word | |
3095 | with this construct. | |
3096 | .PP | |
3097 | There are two formats for redirecting standard output and | |
3098 | standard error: | |
3099 | .RS | |
3100 | .PP | |
3101 | \fB&>\fP\fIword\fP | |
3102 | .RE | |
3103 | and | |
3104 | .RS | |
3105 | \fB>&\fP\fIword\fP | |
3106 | .RE | |
3107 | .PP | |
3108 | Of the two forms, the first is preferred. | |
3109 | This is semantically equivalent to | |
3110 | .RS | |
3111 | .PP | |
3112 | \fB>\fP\fIword\fP 2\fB>&\fP1 | |
3113 | .RE | |
3114 | .SS Here Documents | |
3115 | .PP | |
3116 | This type of redirection instructs the shell to read input from the | |
3117 | current source until a line containing only | |
3118 | .I word | |
3119 | (with no trailing blanks) | |
3120 | is seen. All of | |
3121 | the lines read up to that point are then used as the standard | |
3122 | input for a command. | |
3123 | .PP | |
7117c2d2 | 3124 | The format of here-documents is: |
726f6388 JA |
3125 | .RS |
3126 | .PP | |
3127 | .nf | |
3128 | \fB<<\fP[\fB\-\fP]\fIword\fP | |
f73dda09 | 3129 | \fIhere-document\fP |
726f6388 JA |
3130 | \fIdelimiter\fP |
3131 | .fi | |
3132 | .RE | |
3133 | .PP | |
bb70624e JA |
3134 | No parameter expansion, command substitution, arithmetic expansion, |
3135 | or pathname expansion is performed on | |
726f6388 JA |
3136 | .IR word . |
3137 | If any characters in | |
3138 | .I word | |
3139 | are quoted, the | |
3140 | .I delimiter | |
3141 | is the result of quote removal on | |
3142 | .IR word , | |
cce855bc JA |
3143 | and the lines in the here-document are not expanded. |
3144 | If \fIword\fP is unquoted, | |
726f6388 JA |
3145 | all lines of the here-document are subjected to parameter expansion, |
3146 | command substitution, and arithmetic expansion. In the latter | |
bb70624e | 3147 | case, the character sequence |
726f6388 JA |
3148 | .B \e<newline> |
3149 | is ignored, and | |
3150 | .B \e | |
3151 | must be used to quote the characters | |
3152 | .BR \e , | |
3153 | .BR $ , | |
3154 | and | |
3155 | .BR ` . | |
3156 | .PP | |
3157 | If the redirection operator is | |
3158 | .BR <<\- , | |
3159 | then all leading tab characters are stripped from input lines and the | |
3160 | line containing | |
3161 | .IR delimiter . | |
3162 | This allows | |
3163 | here-documents within shell scripts to be indented in a | |
3164 | natural fashion. | |
7117c2d2 JA |
3165 | .SS "Here Strings" |
3166 | A variant of here documents, the format is: | |
3167 | .RS | |
3168 | .PP | |
3169 | .nf | |
3170 | \fB<<<\fP\fIword\fP | |
3171 | .fi | |
3172 | .RE | |
3173 | .PP | |
3174 | The \fIword\fP is expanded and supplied to the command on its standard | |
3175 | input. | |
726f6388 JA |
3176 | .SS "Duplicating File Descriptors" |
3177 | .PP | |
3178 | The redirection operator | |
3179 | .RS | |
3180 | .PP | |
3181 | [\fIn\fP]\fB<&\fP\fIword\fP | |
3182 | .RE | |
3183 | .PP | |
3184 | is used to duplicate input file descriptors. | |
3185 | If | |
3186 | .I word | |
3187 | expands to one or more digits, the file descriptor denoted by | |
3188 | .I n | |
cce855bc JA |
3189 | is made to be a copy of that file descriptor. |
3190 | If the digits in | |
3191 | .I word | |
3192 | do not specify a file descriptor open for input, a redirection error occurs. | |
3193 | If | |
726f6388 JA |
3194 | .I word |
3195 | evaluates to | |
3196 | .BR \- , | |
3197 | file descriptor | |
3198 | .I n | |
3199 | is closed. If | |
3200 | .I n | |
3201 | is not specified, the standard input (file descriptor 0) is used. | |
3202 | .PP | |
3203 | The operator | |
3204 | .RS | |
3205 | .PP | |
3206 | [\fIn\fP]\fB>&\fP\fIword\fP | |
3207 | .RE | |
3208 | .PP | |
3209 | is used similarly to duplicate output file descriptors. If | |
3210 | .I n | |
3211 | is not specified, the standard output (file descriptor 1) is used. | |
cce855bc JA |
3212 | If the digits in |
3213 | .I word | |
3214 | do not specify a file descriptor open for output, a redirection error occurs. | |
726f6388 JA |
3215 | As a special case, if \fIn\fP is omitted, and \fIword\fP does not |
3216 | expand to one or more digits, the standard output and standard | |
3217 | error are redirected as described previously. | |
7117c2d2 JA |
3218 | .SS "Moving File Descriptors" |
3219 | .PP | |
3220 | The redirection operator | |
3221 | .RS | |
3222 | .PP | |
3223 | [\fIn\fP]\fB<&\fP\fIdigit\fP\fB\-\fP | |
3224 | .RE | |
3225 | .PP | |
3226 | moves the file descriptor \fIdigit\fP to file descriptor | |
3227 | .IR n , | |
3228 | or the standard input (file descriptor 0) if \fIn\fP is not specified. | |
3229 | \fIdigit\fP is closed after being duplicated to \fIn\fP. | |
3230 | .PP | |
3231 | Similarly, the redirection operator | |
3232 | .RS | |
3233 | .PP | |
3234 | [\fIn\fP]\fB>&\fP\fIdigit\fP\fB\-\fP | |
3235 | .RE | |
3236 | .PP | |
3237 | moves the file descriptor \fIdigit\fP to file descriptor | |
3238 | .IR n , | |
3239 | or the standard output (file descriptor 1) if \fIn\fP is not specified. | |
726f6388 JA |
3240 | .SS "Opening File Descriptors for Reading and Writing" |
3241 | .PP | |
3242 | The redirection operator | |
3243 | .RS | |
3244 | .PP | |
3245 | [\fIn\fP]\fB<>\fP\fIword\fP | |
3246 | .RE | |
3247 | .PP | |
3248 | causes the file whose name is the expansion of | |
3249 | .I word | |
3250 | to be opened for both reading and writing on file descriptor | |
3251 | .IR n , | |
ccc6cda3 | 3252 | or on file descriptor 0 if |
726f6388 JA |
3253 | .I n |
3254 | is not specified. If the file does not exist, it is created. | |
726f6388 | 3255 | .SH ALIASES |
bb70624e | 3256 | \fIAliases\fP allow a string to be substituted for a word when it is used |
cce855bc | 3257 | as the first word of a simple command. |
bb70624e | 3258 | The shell maintains a list of aliases that may be set and unset with the |
726f6388 JA |
3259 | .B alias |
3260 | and | |
3261 | .B unalias | |
3262 | builtin commands (see | |
3263 | .SM | |
3264 | .B SHELL BUILTIN COMMANDS | |
3265 | below). | |
de8913bd | 3266 | The first word of each simple command, if unquoted, |
726f6388 JA |
3267 | is checked to see if it has an |
3268 | alias. If so, that word is replaced by the text of the alias. | |
de8913bd CR |
3269 | The characters \fB/\fP, \fB$\fP, \fB`\fP, and \fB=\fP and |
3270 | any of the shell \fImetacharacters\fP or quoting characters | |
3271 | listed above may not appear in an alias name. | |
3272 | The replacement text may contain any valid shell input, | |
3273 | including shell metacharacters. | |
3274 | The first word of the replacement text is tested | |
726f6388 | 3275 | for aliases, but a word that is identical to an alias being expanded |
de8913bd CR |
3276 | is not expanded a second time. |
3277 | This means that one may alias | |
726f6388 JA |
3278 | .B ls |
3279 | to | |
3280 | .BR "ls \-F" , | |
3281 | for instance, and | |
3282 | .B bash | |
3283 | does not try to recursively expand the replacement text. | |
3284 | If the last character of the alias value is a | |
3285 | .IR blank , | |
3286 | then the next command | |
3287 | word following the alias is also checked for alias expansion. | |
3288 | .PP | |
3289 | Aliases are created and listed with the | |
3290 | .B alias | |
3291 | command, and removed with the | |
3292 | .B unalias | |
3293 | command. | |
3294 | .PP | |
ccc6cda3 | 3295 | There is no mechanism for using arguments in the replacement text. |
bb70624e JA |
3296 | If arguments are needed, a shell function should be used (see |
3297 | .SM | |
3298 | .B FUNCTIONS | |
3299 | below). | |
726f6388 | 3300 | .PP |
ccc6cda3 JA |
3301 | Aliases are not expanded when the shell is not interactive, unless |
3302 | the | |
3303 | .B expand_aliases | |
3304 | shell option is set using | |
3305 | .B shopt | |
3306 | (see the description of | |
3307 | .B shopt | |
3308 | under | |
3309 | .SM | |
3310 | \fBSHELL BUILTIN COMMANDS\fP | |
3311 | below). | |
726f6388 JA |
3312 | .PP |
3313 | The rules concerning the definition and use of aliases are | |
3314 | somewhat confusing. | |
3315 | .B Bash | |
3316 | always reads at least one complete line | |
3317 | of input before executing any | |
3318 | of the commands on that line. Aliases are expanded when a | |
3319 | command is read, not when it is executed. Therefore, an | |
3320 | alias definition appearing on the same line as another | |
3321 | command does not take effect until the next line of input is read. | |
ccc6cda3 | 3322 | The commands following the alias definition |
726f6388 JA |
3323 | on that line are not affected by the new alias. |
3324 | This behavior is also an issue when functions are executed. | |
cce855bc | 3325 | Aliases are expanded when a function definition is read, |
726f6388 JA |
3326 | not when the function is executed, because a function definition |
3327 | is itself a compound command. As a consequence, aliases | |
3328 | defined in a function are not available until after that | |
3329 | function is executed. To be safe, always put | |
3330 | alias definitions on a separate line, and do not use | |
3331 | .B alias | |
3332 | in compound commands. | |
3333 | .PP | |
cce855bc | 3334 | For almost every purpose, aliases are superseded by |
726f6388 | 3335 | shell functions. |
ccc6cda3 JA |
3336 | .SH FUNCTIONS |
3337 | A shell function, defined as described above under | |
3338 | .SM | |
3339 | .BR "SHELL GRAMMAR" , | |
3340 | stores a series of commands for later execution. | |
bb70624e JA |
3341 | When the name of a shell function is used as a simple command name, |
3342 | the list of commands associated with that function name is executed. | |
ccc6cda3 JA |
3343 | Functions are executed in the context of the |
3344 | current shell; no new process is created to interpret | |
3345 | them (contrast this with the execution of a shell script). | |
3346 | When a function is executed, the arguments to the | |
3347 | function become the positional parameters | |
bb70624e JA |
3348 | during its execution. |
3349 | The special parameter | |
ccc6cda3 | 3350 | .B # |
de8913bd | 3351 | is updated to reflect the change. Special parameter 0 |
bb70624e | 3352 | is unchanged. |
d3a24ed2 | 3353 | The first element of the |
bb70624e JA |
3354 | .SM |
3355 | .B FUNCNAME | |
3356 | variable is set to the name of the function while the function | |
3357 | is executing. | |
3358 | All other aspects of the shell execution | |
ccc6cda3 JA |
3359 | environment are identical between a function and its caller |
3360 | with the exception that the | |
3361 | .SM | |
3362 | .B DEBUG | |
76a8d78d CR |
3363 | and |
3364 | .B RETURN | |
3365 | traps (see the description of the | |
ccc6cda3 JA |
3366 | .B trap |
3367 | builtin under | |
3368 | .SM | |
3369 | .B SHELL BUILTIN COMMANDS | |
76a8d78d | 3370 | below) are not inherited unless the function has been given the |
7117c2d2 JA |
3371 | \fBtrace\fP attribute (see the description of the |
3372 | .SM | |
3373 | .B declare | |
d3a24ed2 CR |
3374 | builtin below) or the |
3375 | \fB\-o functrace\fP shell option has been enabled with | |
3376 | the \fBset\fP builtin | |
76a8d78d | 3377 | (in which case all functions inherit the \fBDEBUG\fP and \fBRETURN\fP traps). |
726f6388 | 3378 | .PP |
ccc6cda3 JA |
3379 | Variables local to the function may be declared with the |
3380 | .B local | |
3381 | builtin command. Ordinarily, variables and their values | |
3382 | are shared between the function and its caller. | |
726f6388 | 3383 | .PP |
ccc6cda3 JA |
3384 | If the builtin command |
3385 | .B return | |
3386 | is executed in a function, the function completes and | |
3387 | execution resumes with the next command after the function | |
d3a24ed2 CR |
3388 | call. |
3389 | Any command associated with the \fBRETURN\fP trap is executed | |
3390 | before execution resumes. | |
3391 | When a function completes, the values of the | |
ccc6cda3 JA |
3392 | positional parameters and the special parameter |
3393 | .B # | |
cce855bc | 3394 | are restored to the values they had prior to the function's |
ccc6cda3 | 3395 | execution. |
726f6388 | 3396 | .PP |
ccc6cda3 JA |
3397 | Function names and definitions may be listed with the |
3398 | .B \-f | |
726f6388 | 3399 | option to the |
ccc6cda3 JA |
3400 | .B declare |
3401 | or | |
3402 | .B typeset | |
3403 | builtin commands. The | |
3404 | .B \-F | |
3405 | option to | |
3406 | .B declare | |
3407 | or | |
3408 | .B typeset | |
d3a24ed2 CR |
3409 | will list the function names only |
3410 | (and optionally the source file and line number, if the \fBextdebug\fP | |
3411 | shell option is enabled). | |
ccc6cda3 JA |
3412 | Functions may be exported so that subshells |
3413 | automatically have them defined with the | |
3414 | .B \-f | |
3415 | option to the | |
3416 | .B export | |
3417 | builtin. | |
d3a24ed2 CR |
3418 | Note that shell functions and variables with the same name may result |
3419 | in multiple identically-named entries in the environment passed to the | |
3420 | shell's children. | |
3421 | Care should be taken in cases where this may cause a problem. | |
726f6388 | 3422 | .PP |
ccc6cda3 JA |
3423 | Functions may be recursive. No limit is imposed on the number |
3424 | of recursive calls. | |
cce855bc JA |
3425 | .SH "ARITHMETIC EVALUATION" |
3426 | The shell allows arithmetic expressions to be evaluated, under | |
d3a24ed2 CR |
3427 | certain circumstances (see the \fBlet\fP and \fBdeclare\fP builtin |
3428 | commands and \fBArithmetic Expansion\fP). | |
7117c2d2 | 3429 | Evaluation is done in fixed-width integers with no check for overflow, |
cce855bc | 3430 | though division by 0 is trapped and flagged as an error. |
d3a24ed2 CR |
3431 | The operators and their precedence, associativity, and values |
3432 | are the same as in the C language. | |
cce855bc JA |
3433 | The following list of operators is grouped into levels of |
3434 | equal-precedence operators. | |
3435 | The levels are listed in order of decreasing precedence. | |
726f6388 | 3436 | .PP |
cce855bc JA |
3437 | .PD 0 |
3438 | .TP | |
bb70624e JA |
3439 | .B \fIid\fP++ \fIid\fP\-\- |
3440 | variable post-increment and post-decrement | |
3441 | .TP | |
3442 | .B ++\fIid\fP \-\-\fIid\fP | |
3443 | variable pre-increment and pre-decrement | |
3444 | .TP | |
cce855bc JA |
3445 | .B \- + |
3446 | unary minus and plus | |
3447 | .TP | |
3448 | .B ! ~ | |
3449 | logical and bitwise negation | |
3450 | .TP | |
3451 | .B ** | |
3452 | exponentiation | |
3453 | .TP | |
3454 | .B * / % | |
3455 | multiplication, division, remainder | |
3456 | .TP | |
3457 | .B + \- | |
3458 | addition, subtraction | |
3459 | .TP | |
3460 | .B << >> | |
3461 | left and right bitwise shifts | |
3462 | .TP | |
3463 | .B <= >= < > | |
3464 | comparison | |
3465 | .TP | |
3466 | .B == != | |
3467 | equality and inequality | |
3468 | .TP | |
3469 | .B & | |
3470 | bitwise AND | |
3471 | .TP | |
3472 | .B ^ | |
3473 | bitwise exclusive OR | |
3474 | .TP | |
3475 | .B | | |
3476 | bitwise OR | |
3477 | .TP | |
3478 | .B && | |
3479 | logical AND | |
3480 | .TP | |
3481 | .B || | |
3482 | logical OR | |
3483 | .TP | |
3484 | .B \fIexpr\fP?\fIexpr\fP:\fIexpr\fP | |
d3a24ed2 | 3485 | conditional operator |
cce855bc JA |
3486 | .TP |
3487 | .B = *= /= %= += \-= <<= >>= &= ^= |= | |
3488 | assignment | |
bb70624e JA |
3489 | .TP |
3490 | .B \fIexpr1\fP , \fIexpr2\fP | |
3491 | comma | |
cce855bc | 3492 | .PD |
ccc6cda3 | 3493 | .PP |
cce855bc | 3494 | Shell variables are allowed as operands; parameter expansion is |
bb70624e JA |
3495 | performed before the expression is evaluated. |
3496 | Within an expression, shell variables may also be referenced by name | |
3497 | without using the parameter expansion syntax. | |
d3a24ed2 CR |
3498 | A shell variable that is null or unset evaluates to 0 when referenced |
3499 | by name without using the parameter expansion syntax. | |
bb70624e | 3500 | The value of a variable is evaluated as an arithmetic expression |
d3a24ed2 CR |
3501 | when it is referenced, or when a variable which has been given the |
3502 | \fIinteger\fP attribute using \fBdeclare -i\fP is assigned a value. | |
3503 | A null value evaluates to 0. | |
bb70624e | 3504 | A shell variable need not have its integer attribute |
cce855bc | 3505 | turned on to be used in an expression. |
ccc6cda3 | 3506 | .PP |
cce855bc JA |
3507 | Constants with a leading 0 are interpreted as octal numbers. |
3508 | A leading 0x or 0X denotes hexadecimal. | |
3509 | Otherwise, numbers take the form [\fIbase#\fP]n, where \fIbase\fP | |
3510 | is a decimal number between 2 and 64 representing the arithmetic | |
3511 | base, and \fIn\fP is a number in that base. | |
bb70624e | 3512 | If \fIbase#\fP is omitted, then base 10 is used. |
cce855bc | 3513 | The digits greater than 9 are represented by the lowercase letters, |
f73dda09 | 3514 | the uppercase letters, @, and _, in that order. |
cce855bc | 3515 | If \fIbase\fP is less than or equal to 36, lowercase and uppercase |
f75912ae | 3516 | letters may be used interchangeably to represent numbers between 10 |
cce855bc | 3517 | and 35. |
ccc6cda3 | 3518 | .PP |
cce855bc JA |
3519 | Operators are evaluated in order of precedence. Sub-expressions in |
3520 | parentheses are evaluated first and may override the precedence | |
3521 | rules above. | |
3522 | .SH "CONDITIONAL EXPRESSIONS" | |
3523 | Conditional expressions are used by the \fB[[\fP compound command and | |
3524 | the \fBtest\fP and \fB[\fP builtin commands to test file attributes | |
3525 | and perform string and arithmetic comparisons. | |
3526 | Expressions are formed from the following unary or binary primaries. | |
3527 | If any \fIfile\fP argument to one of the primaries is of the form | |
bb70624e JA |
3528 | \fI/dev/fd/n\fP, then file descriptor \fIn\fP is checked. |
3529 | If the \fIfile\fP argument to one of the primaries is one of | |
3530 | \fI/dev/stdin\fP, \fI/dev/stdout\fP, or \fI/dev/stderr\fP, file | |
3531 | descriptor 0, 1, or 2, respectively, is checked. | |
be7d8f2d CR |
3532 | .PP |
3533 | Unless otherwise specified, primaries that operate on files follow symbolic | |
3534 | links and operate on the target of the link, rather than the link itself. | |
cce855bc JA |
3535 | .sp 1 |
3536 | .PD 0 | |
3537 | .TP | |
3538 | .B \-a \fIfile\fP | |
3539 | True if \fIfile\fP exists. | |
3540 | .TP | |
3541 | .B \-b \fIfile\fP | |
3542 | True if \fIfile\fP exists and is a block special file. | |
3543 | .TP | |
3544 | .B \-c \fIfile\fP | |
3545 | True if \fIfile\fP exists and is a character special file. | |
3546 | .TP | |
3547 | .B \-d \fIfile\fP | |
3548 | True if \fIfile\fP exists and is a directory. | |
3549 | .TP | |
3550 | .B \-e \fIfile\fP | |
3551 | True if \fIfile\fP exists. | |
3552 | .TP | |
3553 | .B \-f \fIfile\fP | |
3554 | True if \fIfile\fP exists and is a regular file. | |
3555 | .TP | |
3556 | .B \-g \fIfile\fP | |
3557 | True if \fIfile\fP exists and is set-group-id. | |
3558 | .TP | |
b72432fd JA |
3559 | .B \-h \fIfile\fP |
3560 | True if \fIfile\fP exists and is a symbolic link. | |
3561 | .TP | |
cce855bc JA |
3562 | .B \-k \fIfile\fP |
3563 | True if \fIfile\fP exists and its ``sticky'' bit is set. | |
3564 | .TP | |
3565 | .B \-p \fIfile\fP | |
3566 | True if \fIfile\fP exists and is a named pipe (FIFO). | |
3567 | .TP | |
3568 | .B \-r \fIfile\fP | |
3569 | True if \fIfile\fP exists and is readable. | |
3570 | .TP | |
3571 | .B \-s \fIfile\fP | |
3572 | True if \fIfile\fP exists and has a size greater than zero. | |
3573 | .TP | |
3574 | .B \-t \fIfd\fP | |
3575 | True if file descriptor | |
3576 | .I fd | |
3577 | is open and refers to a terminal. | |
3578 | .TP | |
3579 | .B \-u \fIfile\fP | |
3580 | True if \fIfile\fP exists and its set-user-id bit is set. | |
3581 | .TP | |
3582 | .B \-w \fIfile\fP | |
3583 | True if \fIfile\fP exists and is writable. | |
3584 | .TP | |
3585 | .B \-x \fIfile\fP | |
3586 | True if \fIfile\fP exists and is executable. | |
3587 | .TP | |
3588 | .B \-O \fIfile\fP | |
3589 | True if \fIfile\fP exists and is owned by the effective user id. | |
3590 | .TP | |
3591 | .B \-G \fIfile\fP | |
3592 | True if \fIfile\fP exists and is owned by the effective group id. | |
3593 | .TP | |
3594 | .B \-L \fIfile\fP | |
3595 | True if \fIfile\fP exists and is a symbolic link. | |
3596 | .TP | |
3597 | .B \-S \fIfile\fP | |
3598 | True if \fIfile\fP exists and is a socket. | |
3599 | .TP | |
3600 | .B \-N \fIfile\fP | |
3601 | True if \fIfile\fP exists and has been modified since it was last read. | |
3602 | .TP | |
3603 | \fIfile1\fP \-\fBnt\fP \fIfile2\fP | |
7117c2d2 JA |
3604 | True if \fIfile1\fP is newer (according to modification date) than \fIfile2\fP, |
3605 | or if \fIfile1\fP exists and \fPfile2\fP does not. | |
cce855bc JA |
3606 | .TP |
3607 | \fIfile1\fP \-\fBot\fP \fIfile2\fP | |
7117c2d2 JA |
3608 | True if \fIfile1\fP is older than \fIfile2\fP, or if \fIfile2\fP exists |
3609 | and \fIfile1\fP does not. | |
cce855bc JA |
3610 | .TP |
3611 | \fIfile1\fP \fB\-ef\fP \fIfile2\fP | |
7117c2d2 | 3612 | True if \fIfile1\fP and \fIfile2\fP refer to the same device and |
cce855bc JA |
3613 | inode numbers. |
3614 | .TP | |
3615 | .B \-o \fIoptname\fP | |
3616 | True if shell option | |
3617 | .I optname | |
3618 | is enabled. | |
3619 | See the list of options under the description of the | |
3620 | .B \-o | |
3621 | option to the | |
3622 | .B set | |
3623 | builtin below. | |
3624 | .TP | |
3625 | .B \-z \fIstring\fP | |
3626 | True if the length of \fIstring\fP is zero. | |
3627 | .TP | |
cce855bc | 3628 | \fIstring\fP |
f085a21f CR |
3629 | .PD 0 |
3630 | .TP | |
3631 | .B \-n \fIstring\fP | |
3632 | .PD | |
cce855bc JA |
3633 | True if the length of |
3634 | .I string | |
3635 | is non-zero. | |
3636 | .TP | |
3637 | \fIstring1\fP \fB==\fP \fIstring2\fP | |
3638 | True if the strings are equal. \fB=\fP may be used in place of | |
7117c2d2 | 3639 | \fB==\fP for strict POSIX compliance. |
cce855bc JA |
3640 | .TP |
3641 | \fIstring1\fP \fB!=\fP \fIstring2\fP | |
3642 | True if the strings are not equal. | |
3643 | .TP | |
3644 | \fIstring1\fP \fB<\fP \fIstring2\fP | |
3645 | True if \fIstring1\fP sorts before \fIstring2\fP lexicographically | |
3646 | in the current locale. | |
3647 | .TP | |
3648 | \fIstring1\fP \fB>\fP \fIstring2\fP | |
3649 | True if \fIstring1\fP sorts after \fIstring2\fP lexicographically | |
3650 | in the current locale. | |
3651 | .TP | |
3652 | .I \fIarg1\fP \fBOP\fP \fIarg2\fP | |
3653 | .SM | |
3654 | .B OP | |
3655 | is one of | |
3656 | .BR \-eq , | |
3657 | .BR \-ne , | |
3658 | .BR \-lt , | |
3659 | .BR \-le , | |
3660 | .BR \-gt , | |
3661 | or | |
3662 | .BR \-ge . | |
3663 | These arithmetic binary operators return true if \fIarg1\fP | |
3664 | is equal to, not equal to, less than, less than or equal to, | |
3665 | greater than, or greater than or equal to \fIarg2\fP, respectively. | |
3666 | .I Arg1 | |
3667 | and | |
3668 | .I arg2 | |
3669 | may be positive or negative integers. | |
3670 | .PD | |
3671 | .SH "SIMPLE COMMAND EXPANSION" | |
3672 | When a simple command is executed, the shell performs the following | |
3673 | expansions, assignments, and redirections, from left to right. | |
3674 | .IP 1. | |
3675 | The words that the parser has marked as variable assignments (those | |
3676 | preceding the command name) and redirections are saved for later | |
3677 | processing. | |
3678 | .IP 2. | |
3679 | The words that are not variable assignments or redirections are | |
3680 | expanded. If any words remain after expansion, the first word | |
3681 | is taken to be the name of the command and the remaining words are | |
3682 | the arguments. | |
3683 | .IP 3. | |
3684 | Redirections are performed as described above under | |
3685 | .SM | |
3686 | .BR REDIRECTION . | |
3687 | .IP 4. | |
3688 | The text after the \fB=\fP in each variable assignment undergoes tilde | |
3689 | expansion, parameter expansion, command substitution, arithmetic expansion, | |
3690 | and quote removal before being assigned to the variable. | |
3691 | .PP | |
3692 | If no command name results, the variable assignments affect the current | |
3693 | shell environment. Otherwise, the variables are added to the environment | |
3694 | of the executed command and do not affect the current shell environment. | |
3695 | If any of the assignments attempts to assign a value to a readonly variable, | |
3696 | an error occurs, and the command exits with a non-zero status. | |
3697 | .PP | |
3698 | If no command name results, redirections are performed, but do not | |
3699 | affect the current shell environment. A redirection error causes the | |
3700 | command to exit with a non-zero status. | |
3701 | .PP | |
3702 | If there is a command name left after expansion, execution proceeds as | |
3703 | described below. Otherwise, the command exits. If one of the expansions | |
3704 | contained a command substitution, the exit status of the command is | |
3705 | the exit status of the last command substitution performed. If there | |
3706 | were no command substitutions, the command exits with a status of zero. | |
3707 | .SH "COMMAND EXECUTION" | |
3708 | After a command has been split into words, if it results in a | |
3709 | simple command and an optional list of arguments, the following | |
3710 | actions are taken. | |
3711 | .PP | |
3712 | If the command name contains no slashes, the shell attempts to | |
3713 | locate it. If there exists a shell function by that name, that | |
3714 | function is invoked as described above in | |
3715 | .SM | |
3716 | .BR FUNCTIONS . | |
3717 | If the name does not match a function, the shell searches for | |
3718 | it in the list of shell builtins. If a match is found, that | |
3719 | builtin is invoked. | |
3720 | .PP | |
3721 | If the name is neither a shell function nor a builtin, | |
3722 | and contains no slashes, | |
3723 | .B bash | |
3724 | searches each element of the | |
3725 | .SM | |
3726 | .B PATH | |
3727 | for a directory containing an executable file by that name. | |
3728 | .B Bash | |
bb70624e | 3729 | uses a hash table to remember the full pathnames of executable |
cce855bc JA |
3730 | files (see |
3731 | .B hash | |
3732 | under | |
3733 | .SM | |
3734 | .B "SHELL BUILTIN COMMANDS" | |
3735 | below). | |
3736 | A full search of the directories in | |
3737 | .SM | |
3738 | .B PATH | |
3739 | is performed only if the command is not found in the hash table. | |
3740 | If the search is unsuccessful, the shell prints an error | |
3741 | message and returns an exit status of 127. | |
3742 | .PP | |
3743 | If the search is successful, or if the command name contains | |
3744 | one or more slashes, the shell executes the named program in a | |
3745 | separate execution environment. | |
3746 | Argument 0 is set to the name given, and the remaining arguments | |
3747 | to the command are set to the arguments given, if any. | |
3748 | .PP | |
3749 | If this execution fails because the file is not in executable | |
3750 | format, and the file is not a directory, it is assumed to be | |
3751 | a \fIshell script\fP, a file | |
3752 | containing shell commands. A subshell is spawned to execute | |
3753 | it. This subshell reinitializes itself, so | |
3754 | that the effect is as if a new shell had been invoked | |
3755 | to handle the script, with the exception that the locations of | |
3756 | commands remembered by the parent (see | |
3757 | .B hash | |
3758 | below under | |
3759 | .SM | |
3760 | \fBSHELL BUILTIN COMMANDS\fP) | |
3761 | are retained by the child. | |
3762 | .PP | |
3763 | If the program is a file beginning with | |
3764 | .BR #! , | |
3765 | the remainder of the first line specifies an interpreter | |
3766 | for the program. The shell executes the | |
3767 | specified interpreter on operating systems that do not | |
3768 | handle this executable format themselves. The arguments to the | |
3769 | interpreter consist of a single optional argument following the | |
3770 | interpreter name on the first line of the program, followed | |
3771 | by the name of the program, followed by the command | |
3772 | arguments, if any. | |
3773 | .SH COMMAND EXECUTION ENVIRONMENT | |
3774 | The shell has an \fIexecution environment\fP, which consists of the | |
3775 | following: | |
3776 | .sp 1 | |
3777 | .IP \(bu | |
3778 | open files inherited by the shell at invocation, as modified by | |
3779 | redirections supplied to the \fBexec\fP builtin | |
3780 | .IP \(bu | |
3781 | the current working directory as set by \fBcd\fP, \fBpushd\fP, or | |
3782 | \fBpopd\fP, or inherited by the shell at invocation | |
3783 | .IP \(bu | |
3784 | the file creation mode mask as set by \fBumask\fP or inherited from | |
3785 | the shell's parent | |
3786 | .IP \(bu | |
3787 | current traps set by \fBtrap\fP | |
3788 | .IP \(bu | |
3789 | shell parameters that are set by variable assignment or with \fBset\fP | |
3790 | or inherited from the shell's parent in the environment | |
3791 | .IP \(bu | |
3792 | shell functions defined during execution or inherited from the shell's | |
3793 | parent in the environment | |
3794 | .IP \(bu | |
3795 | options enabled at invocation (either by default or with command-line | |
3796 | arguments) or by \fBset\fP | |
3797 | .IP \(bu | |
3798 | options enabled by \fBshopt\fP | |
3799 | .IP \(bu | |
3800 | shell aliases defined with \fBalias\fP | |
3801 | .IP \(bu | |
3802 | various process IDs, including those of background jobs, the value | |
3803 | of \fB$$\fP, and the value of \fB$PPID\fP | |
3804 | .PP | |
3805 | When a simple command other than a builtin or shell function | |
3806 | is to be executed, it | |
3807 | is invoked in a separate execution environment that consists of | |
3808 | the following. Unless otherwise noted, the values are inherited | |
3809 | from the shell. | |
3810 | .sp 1 | |
3811 | .IP \(bu | |
3812 | the shell's open files, plus any modifications and additions specified | |
3813 | by redirections to the command | |
3814 | .IP \(bu | |
3815 | the current working directory | |
3816 | .IP \(bu | |
3817 | the file creation mode mask | |
3818 | .IP \(bu | |
d3a24ed2 CR |
3819 | shell variables and functions marked for export, along with variables |
3820 | exported for the command, passed in the environment | |
cce855bc | 3821 | .IP \(bu |
d3a24ed2 CR |
3822 | traps caught by the shell are reset to the values inherited from the |
3823 | shell's parent, and traps ignored by the shell are ignored | |
cce855bc JA |
3824 | .PP |
3825 | A command invoked in this separate environment cannot affect the | |
3826 | shell's execution environment. | |
3827 | .PP | |
d3a24ed2 CR |
3828 | Command substitution, commands grouped with parentheses, |
3829 | and asynchronous commands are invoked in a | |
cce855bc JA |
3830 | subshell environment that is a duplicate of the shell environment, |
3831 | except that traps caught by the shell are reset to the values | |
3832 | that the shell inherited from its parent at invocation. Builtin | |
3833 | commands that are invoked as part of a pipeline are also executed in a | |
3834 | subshell environment. Changes made to the subshell environment | |
3835 | cannot affect the shell's execution environment. | |
f73dda09 JA |
3836 | .PP |
3837 | If a command is followed by a \fB&\fP and job control is not active, the | |
3838 | default standard input for the command is the empty file \fI/dev/null\fP. | |
3839 | Otherwise, the invoked command inherits the file descriptors of the calling | |
3840 | shell as modified by redirections. | |
cce855bc JA |
3841 | .SH ENVIRONMENT |
3842 | When a program is invoked it is given an array of strings | |
3843 | called the | |
3844 | .IR environment . | |
3845 | This is a list of | |
3846 | \fIname\fP\-\fIvalue\fP pairs, of the form | |
3847 | .IR "name\fR=\fPvalue" . | |
3848 | .PP | |
bb70624e JA |
3849 | The shell provides several ways to manipulate the environment. |
3850 | On invocation, the shell scans its own environment and | |
cce855bc JA |
3851 | creates a parameter for each name found, automatically marking |
3852 | it for | |
3853 | .I export | |
3854 | to child processes. Executed commands inherit the environment. | |
3855 | The | |
3856 | .B export | |
3857 | and | |
3858 | .B declare \-x | |
3859 | commands allow parameters and functions to be added to and | |
3860 | deleted from the environment. If the value of a parameter | |
3861 | in the environment is modified, the new value becomes part | |
3862 | of the environment, replacing the old. The environment | |
3863 | inherited by any executed command consists of the shell's | |
3864 | initial environment, whose values may be modified in the shell, | |
3865 | less any pairs removed by the | |
3866 | .B unset | |
3867 | command, plus any additions via the | |
3868 | .B export | |
3869 | and | |
3870 | .B declare \-x | |
3871 | commands. | |
3872 | .PP | |
3873 | The environment for any | |
3874 | .I simple command | |
3875 | or function may be augmented temporarily by prefixing it with | |
3876 | parameter assignments, as described above in | |
3877 | .SM | |
3878 | .BR PARAMETERS . | |
3879 | These assignment statements affect only the environment seen | |
3880 | by that command. | |
3881 | .PP | |
3882 | If the | |
3883 | .B \-k | |
3884 | option is set (see the | |
3885 | .B set | |
3886 | builtin command below), then | |
3887 | .I all | |
3888 | parameter assignments are placed in the environment for a command, | |
3889 | not just those that precede the command name. | |
3890 | .PP | |
3891 | When | |
3892 | .B bash | |
3893 | invokes an external command, the variable | |
3894 | .B _ | |
3895 | is set to the full file name of the command and passed to that | |
ccc6cda3 JA |
3896 | command in its environment. |
3897 | .SH "EXIT STATUS" | |
cce855bc | 3898 | For the shell's purposes, a command which exits with a |
ccc6cda3 JA |
3899 | zero exit status has succeeded. An exit status of zero |
3900 | indicates success. A non-zero exit status indicates failure. | |
bb70624e JA |
3901 | When a command terminates on a fatal signal \fIN\fP, \fBbash\fP uses |
3902 | the value of 128+\fIN\fP as the exit status. | |
ccc6cda3 JA |
3903 | .PP |
3904 | If a command is not found, the child process created to | |
3905 | execute it returns a status of 127. If a command is found | |
3906 | but is not executable, the return status is 126. | |
3907 | .PP | |
cce855bc JA |
3908 | If a command fails because of an error during expansion or redirection, |
3909 | the exit status is greater than zero. | |
3910 | .PP | |
ccc6cda3 JA |
3911 | Shell builtin commands return a status of 0 (\fItrue\fP) if |
3912 | successful, and non-zero (\fIfalse\fP) if an error occurs | |
3913 | while they execute. | |
3914 | All builtins return an exit status of 2 to indicate incorrect usage. | |
3915 | .PP | |
3916 | \fBBash\fP itself returns the exit status of the last command | |
3917 | executed, unless a syntax error occurs, in which case it exits | |
3918 | with a non-zero value. See also the \fBexit\fP builtin | |
3919 | command below. | |
3920 | .SH SIGNALS | |
cce855bc | 3921 | When \fBbash\fP is interactive, in the absence of any traps, it ignores |
ccc6cda3 JA |
3922 | .SM |
3923 | .B SIGTERM | |
3924 | (so that \fBkill 0\fP does not kill an interactive shell), | |
3925 | and | |
3926 | .SM | |
3927 | .B SIGINT | |
3928 | is caught and handled (so that the \fBwait\fP builtin is interruptible). | |
3929 | In all cases, \fBbash\fP ignores | |
3930 | .SM | |
3931 | .BR SIGQUIT . | |
3932 | If job control is in effect, | |
3933 | .B bash | |
3934 | ignores | |
3935 | .SM | |
3936 | .BR SIGTTIN , | |
3937 | .SM | |
3938 | .BR SIGTTOU , | |
3939 | and | |
3940 | .SM | |
3941 | .BR SIGTSTP . | |
3942 | .PP | |
5e13499c | 3943 | Non-builtin commands run by \fBbash\fP have signal handlers |
cce855bc JA |
3944 | set to the values inherited by the shell from its parent. |
3945 | When job control is not in effect, asynchronous commands | |
ccc6cda3 JA |
3946 | ignore |
3947 | .SM | |
3948 | .B SIGINT | |
3949 | and | |
3950 | .SM | |
cce855bc | 3951 | .B SIGQUIT |
5e13499c | 3952 | in addition to these inherited handlers. |
ccc6cda3 JA |
3953 | Commands run as a result of command substitution ignore the |
3954 | keyboard-generated job control signals | |
3955 | .SM | |
3956 | .BR SIGTTIN , | |
3957 | .SM | |
3958 | .BR SIGTTOU , | |
3959 | and | |
3960 | .SM | |
3961 | .BR SIGTSTP . | |
3962 | .PP | |
3963 | The shell exits by default upon receipt of a | |
3964 | .SM | |
3965 | .BR SIGHUP . | |
f73dda09 | 3966 | Before exiting, an interactive shell resends the |
ccc6cda3 JA |
3967 | .SM |
3968 | .B SIGHUP | |
cce855bc JA |
3969 | to all jobs, running or stopped. |
3970 | Stopped jobs are sent | |
3971 | .SM | |
3972 | .B SIGCONT | |
3973 | to ensure that they receive the | |
3974 | .SM | |
3975 | .BR SIGHUP . | |
3976 | To prevent the shell from | |
3977 | sending the signal to a particular job, it should be removed from the | |
ccc6cda3 JA |
3978 | jobs table with the |
3979 | .B disown | |
3980 | builtin (see | |
3981 | .SM | |
3982 | .B "SHELL BUILTIN COMMANDS" | |
cce855bc JA |
3983 | below) or marked |
3984 | to not receive | |
ccc6cda3 | 3985 | .SM |
cce855bc JA |
3986 | .B SIGHUP |
3987 | using | |
3988 | .BR "disown \-h" . | |
3989 | .PP | |
3990 | If the | |
3991 | .B huponexit | |
3992 | shell option has been set with | |
3993 | .BR shopt , | |
3994 | .B bash | |
3995 | sends a | |
3996 | .SM | |
3997 | .B SIGHUP | |
3998 | to all jobs when an interactive login shell exits. | |
3999 | .PP | |
b66cc816 | 4000 | If \fBbash\fP is waiting for a command to complete and receives a signal |
5e13499c CR |
4001 | for which a trap has been set, the trap will not be executed until |
4002 | the command completes. | |
cce855bc JA |
4003 | When \fBbash\fP is waiting for an asynchronous command via the \fBwait\fP |
4004 | builtin, the reception of a signal for which a trap has been set will | |
4005 | cause the \fBwait\fP builtin to return immediately with an exit status | |
4006 | greater than 128, immediately after which the trap is executed. | |
ccc6cda3 JA |
4007 | .SH "JOB CONTROL" |
4008 | .I Job control | |
4009 | refers to the ability to selectively stop (\fIsuspend\fP) | |
4010 | the execution of processes and continue (\fIresume\fP) | |
4011 | their execution at a later point. A user typically employs | |
4012 | this facility via an interactive interface supplied jointly | |
4013 | by the system's terminal driver and | |
4014 | .BR bash . | |
4015 | .PP | |
4016 | The shell associates a | |
4017 | .I job | |
4018 | with each pipeline. It keeps a table of currently executing | |
4019 | jobs, which may be listed with the | |
4020 | .B jobs | |
4021 | command. When | |
4022 | .B bash | |
4023 | starts a job asynchronously (in the | |
4024 | .IR background ), | |
4025 | it prints a line that looks like: | |
4026 | .RS | |
4027 | .PP | |
4028 | [1] 25647 | |
4029 | .RE | |
4030 | .PP | |
4031 | indicating that this job is job number 1 and that the process ID | |
4032 | of the last process in the pipeline associated with this job is 25647. | |
4033 | All of the processes in a single pipeline are members of the same job. | |
4034 | .B Bash | |
4035 | uses the | |
4036 | .I job | |
4037 | abstraction as the basis for job control. | |
4038 | .PP | |
4039 | To facilitate the implementation of the user interface to job | |
bb70624e | 4040 | control, the operating system maintains the notion of a \fIcurrent terminal |
ccc6cda3 JA |
4041 | process group ID\fP. Members of this process group (processes whose |
4042 | process group ID is equal to the current terminal process group ID) | |
4043 | receive keyboard-generated signals such as | |
4044 | .SM | |
4045 | .BR SIGINT . | |
4046 | These processes are said to be in the | |
4047 | .IR foreground . | |
4048 | .I Background | |
4049 | processes are those whose process group ID differs from the terminal's; | |
4050 | such processes are immune to keyboard-generated signals. | |
4051 | Only foreground processes are allowed to read from or write to the | |
4052 | terminal. Background processes which attempt to read from (write to) the | |
4053 | terminal are sent a | |
4054 | .SM | |
4055 | .B SIGTTIN (SIGTTOU) | |
4056 | signal by the terminal driver, | |
4057 | which, unless caught, suspends the process. | |
4058 | .PP | |
4059 | If the operating system on which | |
4060 | .B bash | |
4061 | is running supports | |
4062 | job control, | |
4063 | .B bash | |
bb70624e | 4064 | contains facilities to use it. |
ccc6cda3 JA |
4065 | Typing the |
4066 | .I suspend | |
4067 | character (typically | |
4068 | .BR ^Z , | |
4069 | Control-Z) while a process is running | |
bb70624e | 4070 | causes that process to be stopped and returns control to |
ccc6cda3 JA |
4071 | .BR bash . |
4072 | Typing the | |
4073 | .I "delayed suspend" | |
4074 | character (typically | |
4075 | .BR ^Y , | |
4076 | Control-Y) causes the process to be stopped when it | |
4077 | attempts to read input from the terminal, and control to | |
4078 | be returned to | |
4079 | .BR bash . | |
cce855bc | 4080 | The user may then manipulate the state of this job, using the |
ccc6cda3 JA |
4081 | .B bg |
4082 | command to continue it in the background, the | |
4083 | .B fg | |
4084 | command to continue it in the foreground, or | |
4085 | the | |
4086 | .B kill | |
4087 | command to kill it. A \fB^Z\fP takes effect immediately, | |
4088 | and has the additional side effect of causing pending output | |
4089 | and typeahead to be discarded. | |
4090 | .PP | |
4091 | There are a number of ways to refer to a job in the shell. | |
4092 | The character | |
4093 | .B % | |
4094 | introduces a job name. Job number | |
4095 | .I n | |
4096 | may be referred to as | |
4097 | .BR %n . | |
4098 | A job may also be referred to using a prefix of the name used to | |
4099 | start it, or using a substring that appears in its command line. | |
4100 | For example, | |
4101 | .B %ce | |
4102 | refers to a stopped | |
4103 | .B ce | |
4104 | job. If a prefix matches more than one job, | |
4105 | .B bash | |
4106 | reports an error. Using | |
4107 | .BR %?ce , | |
4108 | on the other hand, refers to any job containing the string | |
4109 | .B ce | |
4110 | in its command line. If the substring matches more than one job, | |
4111 | .B bash | |
4112 | reports an error. The symbols | |
4113 | .B %% | |
4114 | and | |
4115 | .B %+ | |
4116 | refer to the shell's notion of the | |
4117 | .IR "current job" , | |
4118 | which is the last job stopped while it was in | |
cce855bc | 4119 | the foreground or started in the background. |
ccc6cda3 JA |
4120 | The |
4121 | .I "previous job" | |
4122 | may be referenced using | |
4123 | .BR %\- . | |
4124 | In output pertaining to jobs (e.g., the output of the | |
4125 | .B jobs | |
4126 | command), the current job is always flagged with a | |
4127 | .BR + , | |
4128 | and the previous job with a | |
4129 | .BR \- . | |
43df7bbb CR |
4130 | A single % (with no accompanying job specification) also refers to the |
4131 | current job. | |
726f6388 | 4132 | .PP |
ccc6cda3 JA |
4133 | Simply naming a job can be used to bring it into the |
4134 | foreground: | |
4135 | .B %1 | |
4136 | is a synonym for | |
4137 | \fB``fg %1''\fP, | |
4138 | bringing job 1 from the background into the foreground. | |
4139 | Similarly, | |
4140 | .B ``%1 &'' | |
4141 | resumes job 1 in the background, equivalent to | |
4142 | \fB``bg %1''\fP. | |
726f6388 | 4143 | .PP |
ccc6cda3 JA |
4144 | The shell learns immediately whenever a job changes state. |
4145 | Normally, | |
4146 | .B bash | |
4147 | waits until it is about to print a prompt before reporting | |
4148 | changes in a job's status so as to not interrupt | |
4149 | any other output. If the | |
4150 | .B \-b | |
4151 | option to the | |
726f6388 | 4152 | .B set |
ccc6cda3 | 4153 | builtin command |
cce855bc | 4154 | is enabled, |
726f6388 | 4155 | .B bash |
ccc6cda3 | 4156 | reports such changes immediately. |
f73dda09 JA |
4157 | Any trap on |
4158 | .SM | |
4159 | .B SIGCHLD | |
4160 | is executed for each child that exits. | |
726f6388 | 4161 | .PP |
ccc6cda3 JA |
4162 | If an attempt to exit |
4163 | .B bash | |
4164 | is made while jobs are stopped, the shell prints a warning message. The | |
4165 | .B jobs | |
4166 | command may then be used to inspect their status. | |
4167 | If a second attempt to exit is made without an intervening command, | |
4168 | the shell does not print another warning, and the stopped | |
4169 | jobs are terminated. | |
726f6388 JA |
4170 | .SH PROMPTING |
4171 | When executing interactively, | |
4172 | .B bash | |
4173 | displays the primary prompt | |
4174 | .SM | |
4175 | .B PS1 | |
4176 | when it is ready to read a command, and the secondary prompt | |
4177 | .SM | |
4178 | .B PS2 | |
4179 | when it needs more input to complete a command. | |
4180 | .B Bash | |
4181 | allows these prompt strings to be customized by inserting a number of | |
4182 | backslash-escaped special characters that are decoded as follows: | |
4183 | .RS | |
4184 | .PD 0 | |
4185 | .TP | |
ccc6cda3 JA |
4186 | .B \ea |
4187 | an ASCII bell character (07) | |
726f6388 JA |
4188 | .TP |
4189 | .B \ed | |
4190 | the date in "Weekday Month Date" format (e.g., "Tue May 26") | |
4191 | .TP | |
7117c2d2 JA |
4192 | .B \eD{\fIformat\fP} |
4193 | the \fIformat\fP is passed to \fIstrftime\fP(3) and the result is inserted | |
4194 | into the prompt string; an empty \fIformat\fP results in a locale-specific | |
4195 | time representation. The braces are required | |
4196 | .TP | |
ccc6cda3 JA |
4197 | .B \ee |
4198 | an ASCII escape character (033) | |
4199 | .TP | |
4200 | .B \eh | |
4201 | the hostname up to the first `.' | |
4202 | .TP | |
4203 | .B \eH | |
4204 | the hostname | |
4205 | .TP | |
bb70624e JA |
4206 | .B \ej |
4207 | the number of jobs currently managed by the shell | |
4208 | .TP | |
4209 | .B \el | |
4210 | the basename of the shell's terminal device name | |
4211 | .TP | |
726f6388 JA |
4212 | .B \en |
4213 | newline | |
4214 | .TP | |
cce855bc JA |
4215 | .B \er |
4216 | carriage return | |
4217 | .TP | |
726f6388 JA |
4218 | .B \es |
4219 | the name of the shell, the basename of | |
4220 | .B $0 | |
4221 | (the portion following the final slash) | |
4222 | .TP | |
ccc6cda3 JA |
4223 | .B \et |
4224 | the current time in 24-hour HH:MM:SS format | |
726f6388 | 4225 | .TP |
ccc6cda3 JA |
4226 | .B \eT |
4227 | the current time in 12-hour HH:MM:SS format | |
4228 | .TP | |
4229 | .B \e@ | |
4230 | the current time in 12-hour am/pm format | |
726f6388 | 4231 | .TP |
f73dda09 JA |
4232 | .B \eA |
4233 | the current time in 24-hour HH:MM format | |
4234 | .TP | |
726f6388 JA |
4235 | .B \eu |
4236 | the username of the current user | |
4237 | .TP | |
ccc6cda3 JA |
4238 | .B \ev |
4239 | the version of \fBbash\fP (e.g., 2.00) | |
726f6388 | 4240 | .TP |
ccc6cda3 | 4241 | .B \eV |
a5e25162 | 4242 | the release of \fBbash\fP, version + patch level (e.g., 2.00.0) |
ccc6cda3 JA |
4243 | .TP |
4244 | .B \ew | |
12d937f9 | 4245 | the current working directory, with \fB$HOME\fP abbreviated with a tilde |
ccc6cda3 JA |
4246 | .TP |
4247 | .B \eW | |
12d937f9 CR |
4248 | the basename of the current working directory, with \fB$HOME\fP |
4249 | abbreviated with a tilde | |
726f6388 JA |
4250 | .TP |
4251 | .B \e! | |
4252 | the history number of this command | |
4253 | .TP | |
ccc6cda3 JA |
4254 | .B \e# |
4255 | the command number of this command | |
4256 | .TP | |
726f6388 JA |
4257 | .B \e$ |
4258 | if the effective UID is 0, a | |
4259 | .BR # , | |
4260 | otherwise a | |
4261 | .B $ | |
4262 | .TP | |
ccc6cda3 JA |
4263 | .B \e\fInnn\fP |
4264 | the character corresponding to the octal number \fInnn\fP | |
726f6388 JA |
4265 | .TP |
4266 | .B \e\e | |
4267 | a backslash | |
4268 | .TP | |
4269 | .B \e[ | |
4270 | begin a sequence of non-printing characters, which could be used to | |
4271 | embed a terminal control sequence into the prompt | |
4272 | .TP | |
4273 | .B \e] | |
4274 | end a sequence of non-printing characters | |
4275 | .PD | |
4276 | .RE | |
4277 | .PP | |
4278 | The command number and the history number are usually different: | |
4279 | the history number of a command is its position in the history | |
4280 | list, which may include commands restored from the history file | |
4281 | (see | |
4282 | .SM | |
4283 | .B HISTORY | |
4284 | below), while the command number is the position in the sequence | |
4285 | of commands executed during the current shell session. | |
4286 | After the string is decoded, it is expanded via | |
bb70624e JA |
4287 | parameter expansion, command substitution, arithmetic |
4288 | expansion, and quote removal, subject to the value of the | |
ccc6cda3 JA |
4289 | .B promptvars |
4290 | shell option (see the description of the | |
4291 | .B shopt | |
4292 | command under | |
4293 | .SM | |
4294 | .B "SHELL BUILTIN COMMANDS" | |
4295 | below). | |
726f6388 JA |
4296 | .SH READLINE |
4297 | This is the library that handles reading input when using an interactive | |
4298 | shell, unless the | |
d166f048 | 4299 | .B \-\-noediting |
ccc6cda3 JA |
4300 | option is given at shell invocation. |
4301 | By default, the line editing commands are similar to those of emacs. | |
726f6388 | 4302 | A vi-style line editing interface is also available. |
ccc6cda3 JA |
4303 | To turn off line editing after the shell is running, use the |
4304 | .B +o emacs | |
4305 | or | |
4306 | .B +o vi | |
4307 | options to the | |
4308 | .B set | |
4309 | builtin (see | |
4310 | .SM | |
4311 | .B SHELL BUILTIN COMMANDS | |
4312 | below). | |
4313 | .SS "Readline Notation" | |
726f6388 JA |
4314 | .PP |
4315 | In this section, the emacs-style notation is used to denote | |
4316 | keystrokes. Control keys are denoted by C\-\fIkey\fR, e.g., C\-n | |
4317 | means Control\-N. Similarly, | |
4318 | .I meta | |
4319 | keys are denoted by M\-\fIkey\fR, so M\-x means Meta\-X. (On keyboards | |
4320 | without a | |
4321 | .I meta | |
4322 | key, M\-\fIx\fP means ESC \fIx\fP, i.e., press the Escape key | |
4323 | then the | |
4324 | .I x | |
4325 | key. This makes ESC the \fImeta prefix\fP. | |
4326 | The combination M\-C\-\fIx\fP means ESC\-Control\-\fIx\fP, | |
4327 | or press the Escape key | |
4328 | then hold the Control key while pressing the | |
4329 | .I x | |
4330 | key.) | |
4331 | .PP | |
ccc6cda3 JA |
4332 | Readline commands may be given numeric |
4333 | .IR arguments , | |
4334 | which normally act as a repeat count. | |
4335 | Sometimes, however, it is the sign of the argument that is significant. | |
4336 | Passing a negative argument to a command that acts in the forward | |
4337 | direction (e.g., \fBkill\-line\fP) causes that command to act in a | |
4338 | backward direction. | |
4339 | Commands whose behavior with arguments deviates from this are noted | |
4340 | below. | |
4341 | .PP | |
4342 | When a command is described as \fIkilling\fP text, the text | |
4343 | deleted is saved for possible future retrieval | |
4344 | (\fIyanking\fP). The killed text is saved in a | |
4345 | \fIkill ring\fP. Consecutive kills cause the text to be | |
4346 | accumulated into one unit, which can be yanked all at once. | |
4347 | Commands which do not kill text separate the chunks of text | |
4348 | on the kill ring. | |
4349 | .SS "Readline Initialization" | |
4350 | .PP | |
4351 | Readline is customized by putting commands in an initialization | |
4352 | file (the \fIinputrc\fP file). | |
4353 | The name of this file is taken from the value of the | |
726f6388 | 4354 | .SM |
ccc6cda3 JA |
4355 | .B INPUTRC |
4356 | variable. If that variable is unset, the default is | |
726f6388 | 4357 | .IR ~/.inputrc . |
ccc6cda3 JA |
4358 | When a program which uses the readline library starts up, the |
4359 | initialization file is read, and the key bindings and variables | |
4360 | are set. | |
4361 | There are only a few basic constructs allowed in the | |
4362 | readline initialization file. | |
4363 | Blank lines are ignored. | |
4364 | Lines beginning with a \fB#\fP are comments. | |
4365 | Lines beginning with a \fB$\fP indicate conditional constructs. | |
4366 | Other lines denote key bindings and variable settings. | |
4367 | .PP | |
4368 | The default key-bindings may be changed with an | |
4369 | .I inputrc | |
4370 | file. | |
726f6388 JA |
4371 | Other programs that use this library may add their own commands |
4372 | and bindings. | |
4373 | .PP | |
4374 | For example, placing | |
4375 | .RS | |
4376 | .PP | |
4377 | M\-Control\-u: universal\-argument | |
4378 | .RE | |
4379 | or | |
4380 | .RS | |
4381 | C\-Meta\-u: universal\-argument | |
4382 | .RE | |
4383 | into the | |
ccc6cda3 | 4384 | .I inputrc |
726f6388 JA |
4385 | would make M\-C\-u execute the readline command |
4386 | .IR universal\-argument . | |
4387 | .PP | |
4388 | The following symbolic character names are recognized: | |
4389 | .IR RUBOUT , | |
4390 | .IR DEL , | |
4391 | .IR ESC , | |
4392 | .IR LFD , | |
4393 | .IR NEWLINE , | |
4394 | .IR RET , | |
4395 | .IR RETURN , | |
4396 | .IR SPC , | |
4397 | .IR SPACE , | |
4398 | and | |
4399 | .IR TAB . | |
bb70624e | 4400 | .PP |
726f6388 JA |
4401 | In addition to command names, readline allows keys to be bound |
4402 | to a string that is inserted when the key is pressed (a \fImacro\fP). | |
ccc6cda3 | 4403 | .SS "Readline Key Bindings" |
726f6388 JA |
4404 | .PP |
4405 | The syntax for controlling key bindings in the | |
cce855bc | 4406 | .I inputrc |
726f6388 JA |
4407 | file is simple. All that is required is the name of the |
4408 | command or the text of a macro and a key sequence to which | |
4409 | it should be bound. The name may be specified in one of two ways: | |
ccc6cda3 | 4410 | as a symbolic key name, possibly with \fIMeta\-\fP or \fIControl\-\fP |
726f6388 | 4411 | prefixes, or as a key sequence. |
28ef6c31 | 4412 | .PP |
cce855bc | 4413 | When using the form \fBkeyname\fP:\^\fIfunction\-name\fP or \fImacro\fP, |
726f6388 JA |
4414 | .I keyname |
4415 | is the name of a key spelled out in English. For example: | |
4416 | .sp | |
4417 | .RS | |
4418 | Control-u: universal\-argument | |
4419 | .br | |
4420 | Meta-Rubout: backward-kill-word | |
4421 | .br | |
ccc6cda3 | 4422 | Control-o: "> output" |
726f6388 JA |
4423 | .RE |
4424 | .LP | |
4425 | In the above example, | |
ccc6cda3 | 4426 | .I C\-u |
726f6388 JA |
4427 | is bound to the function |
4428 | .BR universal\-argument , | |
ccc6cda3 | 4429 | .I M\-DEL |
726f6388 JA |
4430 | is bound to the function |
4431 | .BR backward\-kill\-word , | |
4432 | and | |
ccc6cda3 | 4433 | .I C\-o |
726f6388 JA |
4434 | is bound to run the macro |
4435 | expressed on the right hand side (that is, to insert the text | |
28ef6c31 JA |
4436 | .if t \f(CW> output\fP |
4437 | .if n ``> output'' | |
726f6388 JA |
4438 | into the line). |
4439 | .PP | |
cce855bc | 4440 | In the second form, \fB"keyseq"\fP:\^\fIfunction\-name\fP or \fImacro\fP, |
726f6388 JA |
4441 | .B keyseq |
4442 | differs from | |
4443 | .B keyname | |
4444 | above in that strings denoting | |
4445 | an entire key sequence may be specified by placing the sequence | |
4446 | within double quotes. Some GNU Emacs style key escapes can be | |
28ef6c31 JA |
4447 | used, as in the following example, but the symbolic character names |
4448 | are not recognized. | |
726f6388 JA |
4449 | .sp |
4450 | .RS | |
ccc6cda3 | 4451 | "\eC\-u": universal\-argument |
726f6388 | 4452 | .br |
ccc6cda3 | 4453 | "\eC\-x\eC\-r": re\-read\-init\-file |
726f6388 JA |
4454 | .br |
4455 | "\ee[11~": "Function Key 1" | |
4456 | .RE | |
4457 | .PP | |
4458 | In this example, | |
ccc6cda3 | 4459 | .I C\-u |
726f6388 JA |
4460 | is again bound to the function |
4461 | .BR universal\-argument . | |
ccc6cda3 | 4462 | .I "C\-x C\-r" |
726f6388 JA |
4463 | is bound to the function |
4464 | .BR re\-read\-init\-file , | |
4465 | and | |
4466 | .I "ESC [ 1 1 ~" | |
4467 | is bound to insert the text | |
28ef6c31 JA |
4468 | .if t \f(CWFunction Key 1\fP. |
4469 | .if n ``Function Key 1''. | |
4470 | .PP | |
cce855bc | 4471 | The full set of GNU Emacs style escape sequences is |
726f6388 | 4472 | .RS |
cce855bc | 4473 | .PD 0 |
726f6388 JA |
4474 | .TP |
4475 | .B \eC\- | |
4476 | control prefix | |
4477 | .TP | |
ccc6cda3 | 4478 | .B \eM\- |
726f6388 JA |
4479 | meta prefix |
4480 | .TP | |
4481 | .B \ee | |
4482 | an escape character | |
4483 | .TP | |
4484 | .B \e\e | |
4485 | backslash | |
4486 | .TP | |
4487 | .B \e" | |
4488 | literal " | |
4489 | .TP | |
4490 | .B \e' | |
4491 | literal ' | |
4492 | .RE | |
cce855bc JA |
4493 | .PD |
4494 | .PP | |
4495 | In addition to the GNU Emacs style escape sequences, a second | |
4496 | set of backslash escapes is available: | |
4497 | .RS | |
4498 | .PD 0 | |
4499 | .TP | |
4500 | .B \ea | |
4501 | alert (bell) | |
4502 | .TP | |
4503 | .B \eb | |
4504 | backspace | |
4505 | .TP | |
4506 | .B \ed | |
4507 | delete | |
4508 | .TP | |
4509 | .B \ef | |
4510 | form feed | |
4511 | .TP | |
4512 | .B \en | |
4513 | newline | |
4514 | .TP | |
4515 | .B \er | |
4516 | carriage return | |
4517 | .TP | |
4518 | .B \et | |
4519 | horizontal tab | |
4520 | .TP | |
4521 | .B \ev | |
4522 | vertical tab | |
4523 | .TP | |
4524 | .B \e\fInnn\fP | |
f73dda09 | 4525 | the eight-bit character whose value is the octal value \fInnn\fP |
cce855bc JA |
4526 | (one to three digits) |
4527 | .TP | |
f73dda09 JA |
4528 | .B \ex\fIHH\fP |
4529 | the eight-bit character whose value is the hexadecimal value \fIHH\fP | |
4530 | (one or two hex digits) | |
cce855bc JA |
4531 | .RE |
4532 | .PD | |
726f6388 | 4533 | .PP |
cce855bc JA |
4534 | When entering the text of a macro, single or double quotes must |
4535 | be used to indicate a macro definition. | |
4536 | Unquoted text is assumed to be a function name. | |
4537 | In the macro body, the backslash escapes described above are expanded. | |
4538 | Backslash will quote any other character in the macro text, | |
4539 | including " and '. | |
726f6388 JA |
4540 | .PP |
4541 | .B Bash | |
4542 | allows the current readline key bindings to be displayed or modified | |
4543 | with the | |
4544 | .B bind | |
4545 | builtin command. The editing mode may be switched during interactive | |
4546 | use by using the | |
4547 | .B \-o | |
4548 | option to the | |
4549 | .B set | |
4550 | builtin command (see | |
4551 | .SM | |
4552 | .B SHELL BUILTIN COMMANDS | |
4553 | below). | |
ccc6cda3 | 4554 | .SS "Readline Variables" |
726f6388 JA |
4555 | .PP |
4556 | Readline has variables that can be used to further customize its | |
4557 | behavior. A variable may be set in the | |
4558 | .I inputrc | |
4559 | file with a statement of the form | |
4560 | .RS | |
4561 | .PP | |
4562 | \fBset\fP \fIvariable\-name\fP \fIvalue\fP | |
4563 | .RE | |
4564 | .PP | |
4565 | Except where noted, readline variables can take the values | |
4566 | .B On | |
4567 | or | |
4568 | .BR Off . | |
4569 | The variables and their default values are: | |
4570 | .PP | |
4571 | .PD 0 | |
4572 | .TP | |
726f6388 JA |
4573 | .B bell\-style (audible) |
4574 | Controls what happens when readline wants to ring the terminal bell. | |
4575 | If set to \fBnone\fP, readline never rings the bell. If set to | |
4576 | \fBvisible\fP, readline uses a visible bell if one is available. | |
4577 | If set to \fBaudible\fP, readline attempts to ring the terminal's bell. | |
4578 | .TP | |
453f278a CR |
4579 | .B bind\-tty\-special\-chars (On) |
4580 | If set to \fBOn\fP, readline attempts to bind the control characters | |
4581 | treated specially by the kernel's terminal driver to their readline | |
4582 | equivalents. | |
4583 | .TP | |
726f6388 | 4584 | .B comment\-begin (``#'') |
bb70624e | 4585 | The string that is inserted when the readline |
ccc6cda3 | 4586 | .B insert\-comment |
726f6388 | 4587 | command is executed. |
ccc6cda3 JA |
4588 | This command is bound to |
4589 | .B M\-# | |
4590 | in emacs mode and to | |
4591 | .B # | |
4592 | in vi command mode. | |
726f6388 | 4593 | .TP |
cce855bc JA |
4594 | .B completion\-ignore\-case (Off) |
4595 | If set to \fBOn\fP, readline performs filename matching and completion | |
4596 | in a case\-insensitive fashion. | |
4597 | .TP | |
726f6388 JA |
4598 | .B completion\-query\-items (100) |
4599 | This determines when the user is queried about viewing | |
4600 | the number of possible completions | |
4601 | generated by the \fBpossible\-completions\fP command. | |
4602 | It may be set to any integer value greater than or equal to | |
4603 | zero. If the number of possible completions is greater than | |
4604 | or equal to the value of this variable, the user is asked whether | |
4605 | or not he wishes to view them; otherwise they are simply listed | |
4606 | on the terminal. | |
4607 | .TP | |
ccc6cda3 JA |
4608 | .B convert\-meta (On) |
4609 | If set to \fBOn\fP, readline will convert characters with the | |
4610 | eighth bit set to an ASCII key sequence | |
bb70624e | 4611 | by stripping the eighth bit and prefixing an |
ccc6cda3 JA |
4612 | escape character (in effect, using escape as the \fImeta prefix\fP). |
4613 | .TP | |
4614 | .B disable\-completion (Off) | |
4615 | If set to \fBOn\fP, readline will inhibit word completion. Completion | |
4616 | characters will be inserted into the line as if they had been | |
4617 | mapped to \fBself-insert\fP. | |
4618 | .TP | |
4619 | .B editing\-mode (emacs) | |
4620 | Controls whether readline begins with a set of key bindings similar | |
4621 | to \fIemacs\fP or \fIvi\fP. | |
4622 | .B editing\-mode | |
4623 | can be set to either | |
4624 | .B emacs | |
4625 | or | |
4626 | .BR vi . | |
4627 | .TP | |
4628 | .B enable\-keypad (Off) | |
4629 | When set to \fBOn\fP, readline will try to enable the application | |
4630 | keypad when it is called. Some systems need this to enable the | |
4631 | arrow keys. | |
4632 | .TP | |
4633 | .B expand\-tilde (Off) | |
4634 | If set to \fBon\fP, tilde expansion is performed when readline | |
4635 | attempts word completion. | |
4636 | .TP | |
f73dda09 JA |
4637 | .B history-preserve-point |
4638 | If set to \fBon\fP, the history code attempts to place point at the | |
f75912ae | 4639 | same location on each history line retrieved with \fBprevious-history\fP |
f73dda09 JA |
4640 | or \fBnext-history\fP. |
4641 | .TP | |
ccc6cda3 JA |
4642 | .B horizontal\-scroll\-mode (Off) |
4643 | When set to \fBOn\fP, makes readline use a single line for display, | |
4644 | scrolling the input horizontally on a single screen line when it | |
4645 | becomes longer than the screen width rather than wrapping to a new line. | |
4646 | .TP | |
4647 | .B input\-meta (Off) | |
4648 | If set to \fBOn\fP, readline will enable eight-bit input (that is, | |
4649 | it will not strip the high bit from the characters it reads), | |
4650 | regardless of what the terminal claims it can support. The name | |
4651 | .B meta\-flag | |
4652 | is a synonym for this variable. | |
4653 | .TP | |
b72432fd JA |
4654 | .B isearch\-terminators (``C\-[C\-J'') |
4655 | The string of characters that should terminate an incremental | |
4656 | search without subsequently executing the character as a command. | |
4657 | If this variable has not been given a value, the characters | |
4658 | \fIESC\fP and \fIC\-J\fP will terminate an incremental search. | |
4659 | .TP | |
726f6388 | 4660 | .B keymap (emacs) |
cce855bc | 4661 | Set the current readline keymap. The set of valid keymap names is |
ccc6cda3 JA |
4662 | \fIemacs, emacs\-standard, emacs\-meta, emacs\-ctlx, vi, |
4663 | vi\-command\fP, and | |
4664 | .IR vi\-insert . | |
4665 | \fIvi\fP is equivalent to \fIvi\-command\fP; \fIemacs\fP is | |
4666 | equivalent to \fIemacs\-standard\fP. The default value is | |
726f6388 JA |
4667 | .IR emacs ; |
4668 | the value of | |
4669 | .B editing\-mode | |
4670 | also affects the default keymap. | |
4671 | .TP | |
ccc6cda3 JA |
4672 | .B mark\-directories (On) |
4673 | If set to \fBOn\fP, completed directory names have a slash | |
4674 | appended. | |
4675 | .TP | |
4676 | .B mark\-modified\-lines (Off) | |
4677 | If set to \fBOn\fP, history lines that have been modified are displayed | |
4678 | with a preceding asterisk (\fB*\fP). | |
4679 | .TP | |
7117c2d2 JA |
4680 | .B mark\-symlinked\-directories (Off) |
4681 | If set to \fBOn\fP, completed names which are symbolic links to directories | |
4682 | have a slash appended (subject to the value of | |
4683 | \fBmark\-directories\fP). | |
4684 | .TP | |
f73dda09 JA |
4685 | .B match\-hidden\-files (On) |
4686 | This variable, when set to \fBOn\fP, causes readline to match files whose | |
4687 | names begin with a `.' (hidden files) when performing filename | |
4688 | completion, unless the leading `.' is | |
4689 | supplied by the user in the filename to be completed. | |
4690 | .TP | |
ccc6cda3 JA |
4691 | .B output\-meta (Off) |
4692 | If set to \fBOn\fP, readline will display characters with the | |
4693 | eighth bit set directly rather than as a meta-prefixed escape | |
4694 | sequence. | |
4695 | .TP | |
7117c2d2 JA |
4696 | .B page\-completions (On) |
4697 | If set to \fBOn\fP, readline uses an internal \fImore\fP-like pager | |
4698 | to display a screenful of possible completions at a time. | |
4699 | .TP | |
cce855bc JA |
4700 | .B print\-completions\-horizontally (Off) |
4701 | If set to \fBOn\fP, readline will display completions with matches | |
4702 | sorted horizontally in alphabetical order, rather than down the screen. | |
4703 | .TP | |
726f6388 JA |
4704 | .B show\-all\-if\-ambiguous (Off) |
4705 | This alters the default behavior of the completion functions. If | |
4706 | set to | |
4707 | .BR on , | |
4708 | words which have more than one possible completion cause the | |
4709 | matches to be listed immediately instead of ringing the bell. | |
4710 | .TP | |
d3a24ed2 CR |
4711 | .B show\-all\-if\-unmodified (Off) |
4712 | This alters the default behavior of the completion functions in | |
4713 | a fashion similar to \fBshow\-all\-if\-ambiguous\fP. | |
4714 | If set to | |
4715 | .BR on , | |
4716 | words which have more than one possible completion without any | |
4717 | possible partial completion (the possible completions don't share | |
4718 | a common prefix) cause the matches to be listed immediately instead | |
4719 | of ringing the bell. | |
4720 | .TP | |
ccc6cda3 JA |
4721 | .B visible\-stats (Off) |
4722 | If set to \fBOn\fP, a character denoting a file's type as reported | |
4723 | by \fIstat\fP(2) is appended to the filename when listing possible | |
4724 | completions. | |
726f6388 | 4725 | .PD |
ccc6cda3 | 4726 | .SS "Readline Conditional Constructs" |
726f6388 JA |
4727 | .PP |
4728 | Readline implements a facility similar in spirit to the conditional | |
4729 | compilation features of the C preprocessor which allows key | |
4730 | bindings and variable settings to be performed as the result | |
cce855bc | 4731 | of tests. There are four parser directives used. |
726f6388 JA |
4732 | .IP \fB$if\fP |
4733 | The | |
4734 | .B $if | |
4735 | construct allows bindings to be made based on the | |
4736 | editing mode, the terminal being used, or the application using | |
4737 | readline. The text of the test extends to the end of the line; | |
4738 | no characters are required to isolate it. | |
4739 | .RS | |
4740 | .IP \fBmode\fP | |
4741 | The \fBmode=\fP form of the \fB$if\fP directive is used to test | |
4742 | whether readline is in emacs or vi mode. | |
4743 | This may be used in conjunction | |
4744 | with the \fBset keymap\fP command, for instance, to set bindings in | |
ccc6cda3 | 4745 | the \fIemacs\-standard\fP and \fIemacs\-ctlx\fP keymaps only if |
726f6388 JA |
4746 | readline is starting out in emacs mode. |
4747 | .IP \fBterm\fP | |
4748 | The \fBterm=\fP form may be used to include terminal-specific | |
4749 | key bindings, perhaps to bind the key sequences output by the | |
4750 | terminal's function keys. The word on the right side of the | |
4751 | .B = | |
cce855bc | 4752 | is tested against the both full name of the terminal and the portion |
726f6388 JA |
4753 | of the terminal name before the first \fB\-\fP. This allows |
4754 | .I sun | |
4755 | to match both | |
4756 | .I sun | |
4757 | and | |
4758 | .IR sun\-cmd , | |
4759 | for instance. | |
4760 | .IP \fBapplication\fP | |
4761 | The \fBapplication\fP construct is used to include | |
ccc6cda3 | 4762 | application-specific settings. Each program using the readline |
726f6388 JA |
4763 | library sets the \fIapplication name\fP, and an initialization |
4764 | file can test for a particular value. | |
4765 | This could be used to bind key sequences to functions useful for | |
4766 | a specific program. For instance, the following command adds a | |
4767 | key sequence that quotes the current or previous word in Bash: | |
cce855bc | 4768 | .sp 1 |
726f6388 JA |
4769 | .RS |
4770 | .nf | |
4771 | \fB$if\fP Bash | |
4772 | # Quote the current or previous word | |
ccc6cda3 | 4773 | "\eC\-xq": "\eeb\e"\eef\e"" |
726f6388 JA |
4774 | \fB$endif\fP |
4775 | .fi | |
4776 | .RE | |
4777 | .RE | |
4778 | .IP \fB$endif\fP | |
cce855bc | 4779 | This command, as seen in the previous example, terminates an |
726f6388 JA |
4780 | \fB$if\fP command. |
4781 | .IP \fB$else\fP | |
4782 | Commands in this branch of the \fB$if\fP directive are executed if | |
4783 | the test fails. | |
cce855bc JA |
4784 | .IP \fB$include\fP |
4785 | This directive takes a single filename as an argument and reads commands | |
4786 | and bindings from that file. For example, the following directive | |
4787 | would read \fI/etc/inputrc\fP: | |
4788 | .sp 1 | |
4789 | .RS | |
4790 | .nf | |
4791 | \fB$include\fP \^ \fI/etc/inputrc\fP | |
4792 | .fi | |
4793 | .RE | |
ccc6cda3 | 4794 | .SS Searching |
726f6388 | 4795 | .PP |
ccc6cda3 JA |
4796 | Readline provides commands for searching through the command history |
4797 | (see | |
4798 | .SM | |
4799 | .B HISTORY | |
4800 | below) for lines containing a specified string. | |
4801 | There are two search modes: | |
4802 | .I incremental | |
4803 | and | |
4804 | .IR non-incremental . | |
4805 | .PP | |
4806 | Incremental searches begin before the user has finished typing the | |
4807 | search string. | |
4808 | As each character of the search string is typed, readline displays | |
4809 | the next entry from the history matching the string typed so far. | |
4810 | An incremental search requires only as many characters as needed to | |
4811 | find the desired history entry. | |
bb70624e | 4812 | The characters present in the value of the \fBisearch-terminators\fP |
b72432fd JA |
4813 | variable are used to terminate an incremental search. |
4814 | If that variable has not been assigned a value the Escape and | |
4815 | Control-J characters will terminate an incremental search. | |
ccc6cda3 JA |
4816 | Control-G will abort an incremental search and restore the original |
4817 | line. | |
4818 | When the search is terminated, the history entry containing the | |
4819 | search string becomes the current line. | |
bb70624e | 4820 | .PP |
ccc6cda3 JA |
4821 | To find other matching entries in the history list, type Control-S or |
4822 | Control-R as appropriate. | |
4823 | This will search backward or forward in the history for the next | |
4824 | entry matching the search string typed so far. | |
4825 | Any other key sequence bound to a readline command will terminate | |
4826 | the search and execute that command. | |
4827 | For instance, a \fInewline\fP will terminate the search and accept | |
4828 | the line, thereby executing the command from the history list. | |
4829 | .PP | |
f73dda09 JA |
4830 | Readline remembers the last incremental search string. If two |
4831 | Control-Rs are typed without any intervening characters defining a | |
4832 | new search string, any remembered search string is used. | |
4833 | .PP | |
ccc6cda3 JA |
4834 | Non-incremental searches read the entire search string before starting |
4835 | to search for matching history lines. The search string may be | |
cce855bc | 4836 | typed by the user or be part of the contents of the current line. |
ccc6cda3 | 4837 | .SS "Readline Command Names" |
726f6388 JA |
4838 | .PP |
4839 | The following is a list of the names of the commands and the default | |
4840 | key sequences to which they are bound. | |
ccc6cda3 | 4841 | Command names without an accompanying key sequence are unbound by default. |
bb70624e JA |
4842 | In the following descriptions, \fIpoint\fP refers to the current cursor |
4843 | position, and \fImark\fP refers to a cursor position saved by the | |
4844 | \fBset\-mark\fP command. | |
4845 | The text between the point and mark is referred to as the \fIregion\fP. | |
726f6388 JA |
4846 | .SS Commands for Moving |
4847 | .PP | |
4848 | .PD 0 | |
4849 | .TP | |
4850 | .B beginning\-of\-line (C\-a) | |
4851 | Move to the start of the current line. | |
4852 | .TP | |
4853 | .B end\-of\-line (C\-e) | |
4854 | Move to the end of the line. | |
4855 | .TP | |
4856 | .B forward\-char (C\-f) | |
4857 | Move forward a character. | |
4858 | .TP | |
4859 | .B backward\-char (C\-b) | |
4860 | Move back a character. | |
4861 | .TP | |
4862 | .B forward\-word (M\-f) | |
4863 | Move forward to the end of the next word. Words are composed of | |
4864 | alphanumeric characters (letters and digits). | |
4865 | .TP | |
4866 | .B backward\-word (M\-b) | |
bb70624e | 4867 | Move back to the start of the current or previous word. Words are |
726f6388 JA |
4868 | composed of alphanumeric characters (letters and digits). |
4869 | .TP | |
4870 | .B clear\-screen (C\-l) | |
4871 | Clear the screen leaving the current line at the top of the screen. | |
4872 | With an argument, refresh the current line without clearing the | |
4873 | screen. | |
4874 | .TP | |
4875 | .B redraw\-current\-line | |
ccc6cda3 | 4876 | Refresh the current line. |
726f6388 JA |
4877 | .PD |
4878 | .SS Commands for Manipulating the History | |
4879 | .PP | |
4880 | .PD 0 | |
4881 | .TP | |
4882 | .B accept\-line (Newline, Return) | |
4883 | Accept the line regardless of where the cursor is. If this line is | |
ccc6cda3 | 4884 | non-empty, add it to the history list according to the state of the |
726f6388 JA |
4885 | .SM |
4886 | .B HISTCONTROL | |
4887 | variable. If the line is a modified history | |
4888 | line, then restore the history line to its original state. | |
4889 | .TP | |
4890 | .B previous\-history (C\-p) | |
4891 | Fetch the previous command from the history list, moving back in | |
4892 | the list. | |
4893 | .TP | |
4894 | .B next\-history (C\-n) | |
4895 | Fetch the next command from the history list, moving forward in the | |
4896 | list. | |
4897 | .TP | |
4898 | .B beginning\-of\-history (M\-<) | |
4899 | Move to the first line in the history. | |
4900 | .TP | |
4901 | .B end\-of\-history (M\->) | |
4902 | Move to the end of the input history, i.e., the line currently being | |
4903 | entered. | |
4904 | .TP | |
4905 | .B reverse\-search\-history (C\-r) | |
4906 | Search backward starting at the current line and moving `up' through | |
4907 | the history as necessary. This is an incremental search. | |
4908 | .TP | |
4909 | .B forward\-search\-history (C\-s) | |
4910 | Search forward starting at the current line and moving `down' through | |
4911 | the history as necessary. This is an incremental search. | |
4912 | .TP | |
4913 | .B non\-incremental\-reverse\-search\-history (M\-p) | |
4914 | Search backward through the history starting at the current line | |
ccc6cda3 | 4915 | using a non-incremental search for a string supplied by the user. |
726f6388 JA |
4916 | .TP |
4917 | .B non\-incremental\-forward\-search\-history (M\-n) | |
ccc6cda3 | 4918 | Search forward through the history using a non-incremental search for |
726f6388 JA |
4919 | a string supplied by the user. |
4920 | .TP | |
4921 | .B history\-search\-forward | |
4922 | Search forward through the history for the string of characters | |
bb70624e | 4923 | between the start of the current line and the point. |
ccc6cda3 | 4924 | This is a non-incremental search. |
726f6388 JA |
4925 | .TP |
4926 | .B history\-search\-backward | |
4927 | Search backward through the history for the string of characters | |
ccc6cda3 JA |
4928 | between the start of the current line and the point. |
4929 | This is a non-incremental search. | |
726f6388 JA |
4930 | .TP |
4931 | .B yank\-nth\-arg (M\-C\-y) | |
4932 | Insert the first argument to the previous command (usually | |
28ef6c31 JA |
4933 | the second word on the previous line) at point. |
4934 | With an argument | |
726f6388 JA |
4935 | .IR n , |
4936 | insert the \fIn\fPth word from the previous command (the words | |
4937 | in the previous command begin with word 0). A negative argument | |
4938 | inserts the \fIn\fPth word from the end of the previous command. | |
eb2bb562 CR |
4939 | Once the argument \fIn\fP is computed, the argument is extracted |
4940 | as if the "!\fIn\fP" history expansion had been specified. | |
726f6388 JA |
4941 | .TP |
4942 | .B | |
4943 | yank\-last\-arg (M\-.\^, M\-_\^) | |
ccc6cda3 JA |
4944 | Insert the last argument to the previous command (the last word of |
4945 | the previous history entry). With an argument, | |
4946 | behave exactly like \fByank\-nth\-arg\fP. | |
cce855bc JA |
4947 | Successive calls to \fByank\-last\-arg\fP move back through the history |
4948 | list, inserting the last argument of each line in turn. | |
eb2bb562 CR |
4949 | The history expansion facilities are used to extract the last argument, |
4950 | as if the "!$" history expansion had been specified. | |
726f6388 JA |
4951 | .TP |
4952 | .B shell\-expand\-line (M\-C\-e) | |
cce855bc | 4953 | Expand the line as the shell does. This |
726f6388 JA |
4954 | performs alias and history expansion as well as all of the shell |
4955 | word expansions. See | |
4956 | .SM | |
4957 | .B HISTORY EXPANSION | |
4958 | below for a description of history expansion. | |
4959 | .TP | |
4960 | .B history\-expand\-line (M\-^) | |
d166f048 JA |
4961 | Perform history expansion on the current line. |
4962 | See | |
726f6388 JA |
4963 | .SM |
4964 | .B HISTORY EXPANSION | |
4965 | below for a description of history expansion. | |
4966 | .TP | |
cce855bc JA |
4967 | .B magic\-space |
4968 | Perform history expansion on the current line and insert a space. | |
4969 | See | |
4970 | .SM | |
4971 | .B HISTORY EXPANSION | |
4972 | below for a description of history expansion. | |
4973 | .TP | |
d166f048 JA |
4974 | .B alias\-expand\-line |
4975 | Perform alias expansion on the current line. | |
4976 | See | |
4977 | .SM | |
4978 | .B ALIASES | |
4979 | above for a description of alias expansion. | |
4980 | .TP | |
4981 | .B history\-and\-alias\-expand\-line | |
4982 | Perform history and alias expansion on the current line. | |
4983 | .TP | |
726f6388 JA |
4984 | .B insert\-last\-argument (M\-.\^, M\-_\^) |
4985 | A synonym for \fByank\-last\-arg\fP. | |
4986 | .TP | |
ccc6cda3 | 4987 | .B operate\-and\-get\-next (C\-o) |
726f6388 JA |
4988 | Accept the current line for execution and fetch the next line |
4989 | relative to the current line from the history for editing. Any | |
4990 | argument is ignored. | |
7117c2d2 JA |
4991 | .TP |
4992 | .B edit\-and\-execute\-command (C\-xC\-e) | |
4993 | Invoke an editor on the current command line, and execute the result as shell | |
4994 | commands. | |
4995 | \fBBash\fP attempts to invoke | |
4996 | .SM | |
4997 | .BR $FCEDIT , | |
4998 | .SM | |
4999 | .BR $EDITOR , | |
5000 | and \fIemacs\fP as the editor, in that order. | |
726f6388 JA |
5001 | .PD |
5002 | .SS Commands for Changing Text | |
5003 | .PP | |
5004 | .PD 0 | |
5005 | .TP | |
5006 | .B delete\-char (C\-d) | |
28ef6c31 | 5007 | Delete the character at point. If point is at the |
726f6388 | 5008 | beginning of the line, there are no characters in the line, and |
cce855bc | 5009 | the last character typed was not bound to \fBdelete\-char\fP, |
726f6388 JA |
5010 | then return |
5011 | .SM | |
5012 | .BR EOF . | |
5013 | .TP | |
5014 | .B backward\-delete\-char (Rubout) | |
5015 | Delete the character behind the cursor. When given a numeric argument, | |
ccc6cda3 | 5016 | save the deleted text on the kill ring. |
726f6388 | 5017 | .TP |
b72432fd JA |
5018 | .B forward\-backward\-delete\-char |
5019 | Delete the character under the cursor, unless the cursor is at the | |
5020 | end of the line, in which case the character behind the cursor is | |
f73dda09 | 5021 | deleted. |
b72432fd | 5022 | .TP |
726f6388 | 5023 | .B quoted\-insert (C\-q, C\-v) |
cce855bc | 5024 | Add the next character typed to the line verbatim. This is |
726f6388 JA |
5025 | how to insert characters like \fBC\-q\fP, for example. |
5026 | .TP | |
ccc6cda3 | 5027 | .B tab\-insert (C\-v TAB) |
726f6388 JA |
5028 | Insert a tab character. |
5029 | .TP | |
5030 | .B self\-insert (a,\ b,\ A,\ 1,\ !,\ ...) | |
5031 | Insert the character typed. | |
5032 | .TP | |
5033 | .B transpose\-chars (C\-t) | |
28ef6c31 JA |
5034 | Drag the character before point forward over the character at point, |
5035 | moving point forward as well. | |
5036 | If point is at the end of the line, then this transposes | |
5037 | the two characters before point. | |
bb70624e | 5038 | Negative arguments have no effect. |
726f6388 JA |
5039 | .TP |
5040 | .B transpose\-words (M\-t) | |
bb70624e | 5041 | Drag the word before point past the word after point, |
28ef6c31 | 5042 | moving point over that word as well. |
f73dda09 JA |
5043 | If point is at the end of the line, this transposes |
5044 | the last two words on the line. | |
726f6388 JA |
5045 | .TP |
5046 | .B upcase\-word (M\-u) | |
5047 | Uppercase the current (or following) word. With a negative argument, | |
cce855bc | 5048 | uppercase the previous word, but do not move point. |
726f6388 JA |
5049 | .TP |
5050 | .B downcase\-word (M\-l) | |
5051 | Lowercase the current (or following) word. With a negative argument, | |
cce855bc | 5052 | lowercase the previous word, but do not move point. |
726f6388 JA |
5053 | .TP |
5054 | .B capitalize\-word (M\-c) | |
5055 | Capitalize the current (or following) word. With a negative argument, | |
cce855bc | 5056 | capitalize the previous word, but do not move point. |
7117c2d2 JA |
5057 | .TP |
5058 | .B overwrite\-mode | |
5059 | Toggle overwrite mode. With an explicit positive numeric argument, | |
5060 | switches to overwrite mode. With an explicit non-positive numeric | |
5061 | argument, switches to insert mode. This command affects only | |
5062 | \fBemacs\fP mode; \fBvi\fP mode does overwrite differently. | |
5063 | Each call to \fIreadline()\fP starts in insert mode. | |
5064 | In overwrite mode, characters bound to \fBself\-insert\fP replace | |
5065 | the text at point rather than pushing the text to the right. | |
5066 | Characters bound to \fBbackward\-delete\-char\fP replace the character | |
5067 | before point with a space. By default, this command is unbound. | |
726f6388 JA |
5068 | .PD |
5069 | .SS Killing and Yanking | |
5070 | .PP | |
5071 | .PD 0 | |
5072 | .TP | |
5073 | .B kill\-line (C\-k) | |
bb70624e | 5074 | Kill the text from point to the end of the line. |
726f6388 | 5075 | .TP |
ccc6cda3 | 5076 | .B backward\-kill\-line (C\-x Rubout) |
726f6388 JA |
5077 | Kill backward to the beginning of the line. |
5078 | .TP | |
5079 | .B unix\-line\-discard (C\-u) | |
5080 | Kill backward from point to the beginning of the line. | |
cce855bc | 5081 | The killed text is saved on the kill-ring. |
bb70624e | 5082 | .\" There is no real difference between this and backward-kill-line |
726f6388 JA |
5083 | .TP |
5084 | .B kill\-whole\-line | |
bb70624e | 5085 | Kill all characters on the current line, no matter where point is. |
726f6388 JA |
5086 | .TP |
5087 | .B kill\-word (M\-d) | |
bb70624e JA |
5088 | Kill from point to the end of the current word, or if between |
5089 | words, to the end of the next word. | |
5090 | Word boundaries are the same as those used by \fBforward\-word\fP. | |
726f6388 JA |
5091 | .TP |
5092 | .B backward\-kill\-word (M\-Rubout) | |
bb70624e JA |
5093 | Kill the word behind point. |
5094 | Word boundaries are the same as those used by \fBbackward\-word\fP. | |
726f6388 JA |
5095 | .TP |
5096 | .B unix\-word\-rubout (C\-w) | |
bb70624e | 5097 | Kill the word behind point, using white space as a word boundary. |
bb70624e | 5098 | The killed text is saved on the kill-ring. |
113d85a4 CR |
5099 | .TP |
5100 | .B unix\-filename\-rubout | |
5101 | Kill the word behind point, using white space and the slash character | |
5102 | as the word boundaries. | |
5103 | The killed text is saved on the kill-ring. | |
ccc6cda3 JA |
5104 | .TP |
5105 | .B delete\-horizontal\-space (M\-\e) | |
5106 | Delete all spaces and tabs around point. | |
5107 | .TP | |
5108 | .B kill\-region | |
bb70624e | 5109 | Kill the text in the current region. |
ccc6cda3 JA |
5110 | .TP |
5111 | .B copy\-region\-as\-kill | |
5112 | Copy the text in the region to the kill buffer. | |
726f6388 | 5113 | .TP |
ccc6cda3 JA |
5114 | .B copy\-backward\-word |
5115 | Copy the word before point to the kill buffer. | |
cce855bc | 5116 | The word boundaries are the same as \fBbackward\-word\fP. |
ccc6cda3 JA |
5117 | .TP |
5118 | .B copy\-forward\-word | |
5119 | Copy the word following point to the kill buffer. | |
cce855bc | 5120 | The word boundaries are the same as \fBforward\-word\fP. |
726f6388 JA |
5121 | .TP |
5122 | .B yank (C\-y) | |
28ef6c31 | 5123 | Yank the top of the kill ring into the buffer at point. |
726f6388 JA |
5124 | .TP |
5125 | .B yank\-pop (M\-y) | |
ccc6cda3 | 5126 | Rotate the kill ring, and yank the new top. Only works following |
726f6388 JA |
5127 | .B yank |
5128 | or | |
5129 | .BR yank\-pop . | |
5130 | .PD | |
5131 | .SS Numeric Arguments | |
5132 | .PP | |
5133 | .PD 0 | |
5134 | .TP | |
5135 | .B digit\-argument (M\-0, M\-1, ..., M\-\-) | |
5136 | Add this digit to the argument already accumulating, or start a new | |
5137 | argument. M\-\- starts a negative argument. | |
5138 | .TP | |
5139 | .B universal\-argument | |
d166f048 JA |
5140 | This is another way to specify an argument. |
5141 | If this command is followed by one or more digits, optionally with a | |
5142 | leading minus sign, those digits define the argument. | |
5143 | If the command is followed by digits, executing | |
5144 | .B universal\-argument | |
5145 | again ends the numeric argument, but is otherwise ignored. | |
5146 | As a special case, if this command is immediately followed by a | |
5147 | character that is neither a digit or minus sign, the argument count | |
5148 | for the next command is multiplied by four. | |
726f6388 | 5149 | The argument count is initially one, so executing this function the |
d166f048 JA |
5150 | first time makes the argument count four, a second time makes the |
5151 | argument count sixteen, and so on. | |
726f6388 JA |
5152 | .PD |
5153 | .SS Completing | |
5154 | .PP | |
5155 | .PD 0 | |
5156 | .TP | |
5157 | .B complete (TAB) | |
5158 | Attempt to perform completion on the text before point. | |
5159 | .B Bash | |
5160 | attempts completion treating the text as a variable (if the | |
5161 | text begins with \fB$\fP), username (if the text begins with | |
5162 | \fB~\fP), hostname (if the text begins with \fB@\fP), or | |
5163 | command (including aliases and functions) in turn. If none | |
5164 | of these produces a match, filename completion is attempted. | |
5165 | .TP | |
ccc6cda3 | 5166 | .B possible\-completions (M\-?) |
726f6388 JA |
5167 | List the possible completions of the text before point. |
5168 | .TP | |
ccc6cda3 | 5169 | .B insert\-completions (M\-*) |
726f6388 JA |
5170 | Insert all completions of the text before point |
5171 | that would have been generated by | |
ccc6cda3 | 5172 | \fBpossible\-completions\fP. |
726f6388 | 5173 | .TP |
cce855bc JA |
5174 | .B menu\-complete |
5175 | Similar to \fBcomplete\fP, but replaces the word to be completed | |
5176 | with a single match from the list of possible completions. | |
5177 | Repeated execution of \fBmenu\-complete\fP steps through the list | |
5178 | of possible completions, inserting each match in turn. | |
28ef6c31 | 5179 | At the end of the list of completions, the bell is rung |
f73dda09 | 5180 | (subject to the setting of \fBbell\-style\fP) |
28ef6c31 | 5181 | and the original text is restored. |
cce855bc JA |
5182 | An argument of \fIn\fP moves \fIn\fP positions forward in the list |
5183 | of matches; a negative argument may be used to move backward | |
5184 | through the list. | |
5185 | This command is intended to be bound to \fBTAB\fP, but is unbound | |
5186 | by default. | |
5187 | .TP | |
b72432fd JA |
5188 | .B delete\-char\-or\-list |
5189 | Deletes the character under the cursor if not at the beginning or | |
bb70624e | 5190 | end of the line (like \fBdelete\-char\fP). |
b72432fd | 5191 | If at the end of the line, behaves identically to |
bb70624e | 5192 | \fBpossible\-completions\fP. |
b72432fd JA |
5193 | This command is unbound by default. |
5194 | .TP | |
726f6388 JA |
5195 | .B complete\-filename (M\-/) |
5196 | Attempt filename completion on the text before point. | |
5197 | .TP | |
5198 | .B possible\-filename\-completions (C\-x /) | |
5199 | List the possible completions of the text before point, | |
5200 | treating it as a filename. | |
5201 | .TP | |
5202 | .B complete\-username (M\-~) | |
5203 | Attempt completion on the text before point, treating | |
5204 | it as a username. | |
5205 | .TP | |
5206 | .B possible\-username\-completions (C\-x ~) | |
5207 | List the possible completions of the text before point, | |
5208 | treating it as a username. | |
5209 | .TP | |
5210 | .B complete\-variable (M\-$) | |
5211 | Attempt completion on the text before point, treating | |
5212 | it as a shell variable. | |
5213 | .TP | |
5214 | .B possible\-variable\-completions (C\-x $) | |
5215 | List the possible completions of the text before point, | |
5216 | treating it as a shell variable. | |
5217 | .TP | |
5218 | .B complete\-hostname (M\-@) | |
5219 | Attempt completion on the text before point, treating | |
5220 | it as a hostname. | |
5221 | .TP | |
5222 | .B possible\-hostname\-completions (C\-x @) | |
5223 | List the possible completions of the text before point, | |
5224 | treating it as a hostname. | |
5225 | .TP | |
5226 | .B complete\-command (M\-!) | |
5227 | Attempt completion on the text before point, treating | |
5228 | it as a command name. Command completion attempts to | |
5229 | match the text against aliases, reserved words, shell | |
cce855bc | 5230 | functions, shell builtins, and finally executable filenames, |
726f6388 JA |
5231 | in that order. |
5232 | .TP | |
5233 | .B possible\-command\-completions (C\-x !) | |
5234 | List the possible completions of the text before point, | |
5235 | treating it as a command name. | |
5236 | .TP | |
ccc6cda3 | 5237 | .B dynamic\-complete\-history (M\-TAB) |
726f6388 JA |
5238 | Attempt completion on the text before point, comparing |
5239 | the text against lines from the history list for possible | |
5240 | completion matches. | |
5241 | .TP | |
5242 | .B complete\-into\-braces (M\-{) | |
bb70624e | 5243 | Perform filename completion and insert the list of possible completions |
726f6388 JA |
5244 | enclosed within braces so the list is available to the shell (see |
5245 | .B Brace Expansion | |
5246 | above). | |
5247 | .PD | |
5248 | .SS Keyboard Macros | |
5249 | .PP | |
5250 | .PD 0 | |
5251 | .TP | |
ccc6cda3 | 5252 | .B start\-kbd\-macro (C\-x (\^) |
726f6388 JA |
5253 | Begin saving the characters typed into the current keyboard macro. |
5254 | .TP | |
ccc6cda3 | 5255 | .B end\-kbd\-macro (C\-x )\^) |
726f6388 | 5256 | Stop saving the characters typed into the current keyboard macro |
ccc6cda3 | 5257 | and store the definition. |
726f6388 | 5258 | .TP |
ccc6cda3 | 5259 | .B call\-last\-kbd\-macro (C\-x e) |
726f6388 JA |
5260 | Re-execute the last keyboard macro defined, by making the characters |
5261 | in the macro appear as if typed at the keyboard. | |
5262 | .PD | |
5263 | .SS Miscellaneous | |
5264 | .PP | |
5265 | .PD 0 | |
5266 | .TP | |
5267 | .B re\-read\-init\-file (C\-x C\-r) | |
ccc6cda3 | 5268 | Read in the contents of the \fIinputrc\fP file, and incorporate |
726f6388 JA |
5269 | any bindings or variable assignments found there. |
5270 | .TP | |
5271 | .B abort (C\-g) | |
5272 | Abort the current editing command and | |
5273 | ring the terminal's bell (subject to the setting of | |
5274 | .BR bell\-style ). | |
5275 | .TP | |
ccc6cda3 JA |
5276 | .B do\-uppercase\-version (M\-a, M\-b, M\-\fIx\fP, ...) |
5277 | If the metafied character \fIx\fP is lowercase, run the command | |
5278 | that is bound to the corresponding uppercase character. | |
726f6388 JA |
5279 | .TP |
5280 | .B prefix\-meta (ESC) | |
5281 | Metafy the next character typed. | |
5282 | .SM | |
5283 | .B ESC | |
5284 | .B f | |
5285 | is equivalent to | |
5286 | .BR Meta\-f . | |
5287 | .TP | |
5288 | .B undo (C\-_, C\-x C\-u) | |
5289 | Incremental undo, separately remembered for each line. | |
5290 | .TP | |
5291 | .B revert\-line (M\-r) | |
cce855bc | 5292 | Undo all changes made to this line. This is like executing the |
726f6388 JA |
5293 | .B undo |
5294 | command enough times to return the line to its initial state. | |
5295 | .TP | |
b72432fd | 5296 | .B tilde\-expand (M\-&) |
726f6388 JA |
5297 | Perform tilde expansion on the current word. |
5298 | .TP | |
ccc6cda3 | 5299 | .B set\-mark (C\-@, M\-<space>) |
28ef6c31 | 5300 | Set the mark to the point. If a |
ccc6cda3 JA |
5301 | numeric argument is supplied, the mark is set to that position. |
5302 | .TP | |
5303 | .B exchange\-point\-and\-mark (C\-x C\-x) | |
5304 | Swap the point with the mark. The current cursor position is set to | |
5305 | the saved position, and the old cursor position is saved as the mark. | |
5306 | .TP | |
5307 | .B character\-search (C\-]) | |
5308 | A character is read and point is moved to the next occurrence of that | |
5309 | character. A negative count searches for previous occurrences. | |
5310 | .TP | |
5311 | .B character\-search\-backward (M\-C\-]) | |
5312 | A character is read and point is moved to the previous occurrence of that | |
5313 | character. A negative count searches for subsequent occurrences. | |
5314 | .TP | |
5315 | .B insert\-comment (M\-#) | |
7117c2d2 | 5316 | Without a numeric argument, the value of the readline |
ccc6cda3 | 5317 | .B comment\-begin |
7117c2d2 JA |
5318 | variable is inserted at the beginning of the current line. |
5319 | If a numeric argument is supplied, this command acts as a toggle: if | |
5320 | the characters at the beginning of the line do not match the value | |
5321 | of \fBcomment\-begin\fP, the value is inserted, otherwise | |
5322 | the characters in \fBcomment-begin\fP are deleted from the beginning of | |
5323 | the line. | |
5324 | In either case, the line is accepted as if a newline had been typed. | |
5325 | The default value of | |
bb70624e | 5326 | \fBcomment\-begin\fP causes this command to make the current line |
ccc6cda3 | 5327 | a shell comment. |
7117c2d2 JA |
5328 | If a numeric argument causes the comment character to be removed, the line |
5329 | will be executed by the shell. | |
5330 | .TP | |
5331 | .B glob\-complete\-word (M\-g) | |
5332 | The word before point is treated as a pattern for pathname expansion, | |
5333 | with an asterisk implicitly appended. This pattern is used to | |
5334 | generate a list of matching file names for possible completions. | |
ccc6cda3 JA |
5335 | .TP |
5336 | .B glob\-expand\-word (C\-x *) | |
5337 | The word before point is treated as a pattern for pathname expansion, | |
5338 | and the list of matching file names is inserted, replacing the word. | |
7117c2d2 JA |
5339 | If a numeric argument is supplied, an asterisk is appended before |
5340 | pathname expansion. | |
ccc6cda3 JA |
5341 | .TP |
5342 | .B glob\-list\-expansions (C\-x g) | |
5343 | The list of expansions that would have been generated by | |
5344 | .B glob\-expand\-word | |
5345 | is displayed, and the line is redrawn. | |
7117c2d2 JA |
5346 | If a numeric argument is supplied, an asterisk is appended before |
5347 | pathname expansion. | |
ccc6cda3 | 5348 | .TP |
726f6388 JA |
5349 | .B dump\-functions |
5350 | Print all of the functions and their key bindings to the | |
5351 | readline output stream. If a numeric argument is supplied, | |
5352 | the output is formatted in such a way that it can be made part | |
5353 | of an \fIinputrc\fP file. | |
5354 | .TP | |
ccc6cda3 JA |
5355 | .B dump\-variables |
5356 | Print all of the settable readline variables and their values to the | |
5357 | readline output stream. If a numeric argument is supplied, | |
5358 | the output is formatted in such a way that it can be made part | |
5359 | of an \fIinputrc\fP file. | |
5360 | .TP | |
5361 | .B dump\-macros | |
5362 | Print all of the readline key sequences bound to macros and the | |
22e63b05 | 5363 | strings they output. If a numeric argument is supplied, |
ccc6cda3 JA |
5364 | the output is formatted in such a way that it can be made part |
5365 | of an \fIinputrc\fP file. | |
5366 | .TP | |
726f6388 JA |
5367 | .B display\-shell\-version (C\-x C\-v) |
5368 | Display version information about the current instance of | |
5369 | .BR bash . | |
5370 | .PD | |
bb70624e JA |
5371 | .SS Programmable Completion |
5372 | .PP | |
5373 | When word completion is attempted for an argument to a command for | |
5374 | which a completion specification (a \fIcompspec\fP) has been defined | |
5375 | using the \fBcomplete\fP builtin (see | |
5376 | .SM | |
5377 | .B "SHELL BUILTIN COMMANDS" | |
5378 | below), the programmable completion facilities are invoked. | |
5379 | .PP | |
5380 | First, the command name is identified. | |
5381 | If a compspec has been defined for that command, the | |
5382 | compspec is used to generate the list of possible completions for the word. | |
5383 | If the command word is a full pathname, a compspec for the full | |
5384 | pathname is searched for first. | |
5385 | If no compspec is found for the full pathname, an attempt is made to | |
5386 | find a compspec for the portion following the final slash. | |
5387 | .PP | |
5388 | Once a compspec has been found, it is used to generate the list of | |
5389 | matching words. | |
5390 | If a compspec is not found, the default \fBbash\fP completion as | |
5391 | described above under \fBCompleting\fP is performed. | |
5392 | .PP | |
5393 | First, the actions specified by the compspec are used. | |
5394 | Only matches which are prefixed by the word being completed are | |
5395 | returned. | |
5396 | When the | |
5397 | .B \-f | |
5398 | or | |
5399 | .B \-d | |
5400 | option is used for filename or directory name completion, the shell | |
5401 | variable | |
5402 | .SM | |
5403 | .B FIGNORE | |
5404 | is used to filter the matches. | |
5405 | .PP | |
5406 | Any completions specified by a filename expansion pattern to the | |
5407 | \fB\-G\fP option are generated next. | |
5408 | The words generated by the pattern need not match the word | |
5409 | being completed. | |
5410 | The | |
5411 | .SM | |
5412 | .B GLOBIGNORE | |
5413 | shell variable is not used to filter the matches, but the | |
5414 | .SM | |
5415 | .B FIGNORE | |
5416 | variable is used. | |
5417 | .PP | |
5418 | Next, the string specified as the argument to the \fB\-W\fP option | |
5419 | is considered. | |
5420 | The string is first split using the characters in the | |
5421 | .SM | |
5422 | .B IFS | |
5423 | special variable as delimiters. | |
5424 | Shell quoting is honored. | |
5425 | Each word is then expanded using | |
5426 | brace expansion, tilde expansion, parameter and variable expansion, | |
6e70dbff | 5427 | command substitution, and arithmetic expansion, |
bb70624e JA |
5428 | as described above under |
5429 | .SM | |
5430 | .BR EXPANSION . | |
5431 | The results are split using the rules described above under | |
5432 | \fBWord Splitting\fP. | |
5433 | The results of the expansion are prefix-matched against the word being | |
5434 | completed, and the matching words become the possible completions. | |
5435 | .PP | |
5436 | After these matches have been generated, any shell function or command | |
5437 | specified with the \fB\-F\fP and \fB\-C\fP options is invoked. | |
5438 | When the command or function is invoked, the | |
5439 | .SM | |
5440 | .B COMP_LINE | |
5441 | and | |
5442 | .SM | |
5443 | .B COMP_POINT | |
5444 | variables are assigned values as described above under | |
5445 | \fBShell Variables\fP. | |
5446 | If a shell function is being invoked, the | |
5447 | .SM | |
5448 | .B COMP_WORDS | |
5449 | and | |
5450 | .SM | |
5451 | .B COMP_CWORD | |
5452 | variables are also set. | |
5453 | When the function or command is invoked, the first argument is the | |
5454 | name of the command whose arguments are being completed, the | |
5455 | second argument is the word being completed, and the third argument | |
5456 | is the word preceding the word being completed on the current command line. | |
5457 | No filtering of the generated completions against the word being completed | |
5458 | is performed; the function or command has complete freedom in generating | |
5459 | the matches. | |
5460 | .PP | |
5461 | Any function specified with \fB\-F\fP is invoked first. | |
5462 | The function may use any of the shell facilities, including the | |
5463 | \fBcompgen\fP builtin described below, to generate the matches. | |
5464 | It must put the possible completions in the | |
5465 | .SM | |
5466 | .B COMPREPLY | |
5467 | array variable. | |
5468 | .PP | |
5469 | Next, any command specified with the \fB\-C\fP option is invoked | |
5470 | in an environment equivalent to command substitution. | |
5471 | It should print a list of completions, one per line, to the | |
5472 | standard output. | |
5473 | Backslash may be used to escape a newline, if necessary. | |
5474 | .PP | |
5475 | After all of the possible completions are generated, any filter | |
5476 | specified with the \fB\-X\fP option is applied to the list. | |
5477 | The filter is a pattern as used for pathname expansion; a \fB&\fP | |
5478 | in the pattern is replaced with the text of the word being completed. | |
5479 | A literal \fB&\fP may be escaped with a backslash; the backslash | |
5480 | is removed before attempting a match. | |
5481 | Any completion that matches the pattern will be removed from the list. | |
5482 | A leading \fB!\fP negates the pattern; in this case any completion | |
5483 | not matching the pattern will be removed. | |
5484 | .PP | |
5485 | Finally, any prefix and suffix specified with the \fB\-P\fP and \fB\-S\fP | |
5486 | options are added to each member of the completion list, and the result is | |
5487 | returned to the readline completion code as the list of possible | |
5488 | completions. | |
5489 | .PP | |
28ef6c31 JA |
5490 | If the previously-applied actions do not generate any matches, and the |
5491 | \fB\-o dirnames\fP option was supplied to \fBcomplete\fP when the | |
5492 | compspec was defined, directory name completion is attempted. | |
5493 | .PP | |
d3a24ed2 CR |
5494 | If the \fB\-o plusdirs\fP option was supplied to \fBcomplete\fP when the |
5495 | compspec was defined, directory name completion is attempted and any | |
5496 | matches are added to the results of the other actions. | |
5497 | .PP | |
28ef6c31 JA |
5498 | By default, if a compspec is found, whatever it generates is returned |
5499 | to the completion code as the full set of possible completions. | |
bb70624e JA |
5500 | The default \fBbash\fP completions are not attempted, and the readline |
5501 | default of filename completion is disabled. | |
d3a24ed2 CR |
5502 | If the \fB\-o bashdefault\fP option was supplied to \fBcomplete\fP when |
5503 | the compspec was defined, the \fBbash\fP default completions are attempted | |
28ef6c31 | 5504 | if the compspec generates no matches. |
d3a24ed2 CR |
5505 | If the \fB\-o default\fP option was supplied to \fBcomplete\fP when the |
5506 | compspec was defined, readline's default completion will be performed | |
5507 | if the compspec (and, if attempted, the default \fBbash\fP completions) | |
5508 | generate no matches. | |
7117c2d2 JA |
5509 | .PP |
5510 | When a compspec indicates that directory name completion is desired, | |
5511 | the programmable completion functions force readline to append a slash | |
5512 | to completed names which are symbolic links to directories, subject to | |
5513 | the value of the \fBmark\-directories\fP readline variable, regardless | |
5514 | of the setting of the \fBmark-symlinked\-directories\fP readline variable. | |
726f6388 | 5515 | .SH HISTORY |
ccc6cda3 | 5516 | When the |
d166f048 | 5517 | .B \-o history |
ccc6cda3 JA |
5518 | option to the |
5519 | .B set | |
5520 | builtin is enabled, the shell provides access to the | |
5521 | \fIcommand history\fP, | |
bb70624e JA |
5522 | the list of commands previously typed. |
5523 | The value of the \fBHISTSIZE\fP variable is used as the | |
5524 | number of commands to save in a history list. | |
5525 | The text of the last | |
726f6388 JA |
5526 | .SM |
5527 | .B HISTSIZE | |
bb70624e | 5528 | commands (default 500) is saved. The shell |
726f6388 JA |
5529 | stores each command in the history list prior to parameter and |
5530 | variable expansion (see | |
5531 | .SM | |
5532 | .B EXPANSION | |
5533 | above) but after history expansion is performed, subject to the | |
5534 | values of the shell variables | |
ccc6cda3 JA |
5535 | .SM |
5536 | .B HISTIGNORE | |
726f6388 JA |
5537 | and |
5538 | .SM | |
5539 | .BR HISTCONTROL . | |
bb70624e | 5540 | .PP |
726f6388 JA |
5541 | On startup, the history is initialized from the file named by |
5542 | the variable | |
5543 | .SM | |
5544 | .B HISTFILE | |
5545 | (default \fI~/.bash_history\fP). | |
bb70624e | 5546 | The file named by the value of |
726f6388 JA |
5547 | .SM |
5548 | .B HISTFILE | |
5549 | is truncated, if necessary, to contain no more than | |
bb70624e | 5550 | the number of lines specified by the value of |
726f6388 | 5551 | .SM |
bb70624e | 5552 | .BR HISTFILESIZE . |
ccc6cda3 JA |
5553 | When an interactive shell exits, the last |
5554 | .SM | |
bb70624e | 5555 | .B $HISTSIZE |
ccc6cda3 JA |
5556 | lines are copied from the history list to |
5557 | .SM | |
bb70624e | 5558 | .BR $HISTFILE . |
ccc6cda3 JA |
5559 | If the |
5560 | .B histappend | |
5561 | shell option is enabled | |
5562 | (see the description of | |
5563 | .B shopt | |
5564 | under | |
5565 | .SM | |
5566 | .B "SHELL BUILTIN COMMANDS" | |
5567 | below), the lines are appended to the history file, | |
5568 | otherwise the history file is overwritten. | |
5569 | If | |
5570 | .SM | |
5571 | .B HISTFILE | |
5572 | is unset, or if the history file is unwritable, the history is | |
5573 | not saved. After saving the history, the history file is truncated | |
5574 | to contain no more than | |
5575 | .SM | |
5576 | .B HISTFILESIZE | |
5577 | lines. If | |
5578 | .SM | |
5579 | .B HISTFILESIZE | |
5580 | is not set, no truncation is performed. | |
5581 | .PP | |
726f6388 JA |
5582 | The builtin command |
5583 | .B fc | |
5584 | (see | |
5585 | .SM | |
5586 | .B SHELL BUILTIN COMMANDS | |
5587 | below) may be used to list or edit and re-execute a portion of | |
5588 | the history list. | |
5589 | The | |
5590 | .B history | |
bb70624e | 5591 | builtin may be used to display or modify the history list and |
ccc6cda3 | 5592 | manipulate the history file. |
bb70624e | 5593 | When using command-line editing, search commands |
726f6388 | 5594 | are available in each editing mode that provide access to the |
ccc6cda3 JA |
5595 | history list. |
5596 | .PP | |
5597 | The shell allows control over which commands are saved on the history | |
5598 | list. The | |
726f6388 | 5599 | .SM |
ccc6cda3 JA |
5600 | .B HISTCONTROL |
5601 | and | |
726f6388 | 5602 | .SM |
ccc6cda3 JA |
5603 | .B HISTIGNORE |
5604 | variables may be set to cause the shell to save only a subset of the | |
5605 | commands entered. | |
5606 | The | |
5607 | .B cmdhist | |
5608 | shell option, if enabled, causes the shell to attempt to save each | |
5609 | line of a multi-line command in the same history entry, adding | |
5610 | semicolons where necessary to preserve syntactic correctness. | |
5611 | The | |
5612 | .B lithist | |
5613 | shell option causes the shell to save the command with embedded newlines | |
5614 | instead of semicolons. See the description of the | |
5615 | .B shopt | |
5616 | builtin below under | |
5617 | .SM | |
5618 | .B "SHELL BUILTIN COMMANDS" | |
5619 | for information on setting and unsetting shell options. | |
726f6388 JA |
5620 | .SH "HISTORY EXPANSION" |
5621 | .PP | |
5622 | The shell supports a history expansion feature that | |
5623 | is similar to the history expansion in | |
5624 | .BR csh. | |
5625 | This section describes what syntax features are available. This | |
5626 | feature is enabled by default for interactive shells, and can be | |
5627 | disabled using the | |
5628 | .B \+H | |
5629 | option to the | |
5630 | .B set | |
5631 | builtin command (see | |
5632 | .SM | |
5633 | .B SHELL BUILTIN COMMANDS | |
ccc6cda3 JA |
5634 | below). Non-interactive shells do not perform history expansion |
5635 | by default. | |
5636 | .PP | |
5637 | History expansions introduce words from the history list into | |
5638 | the input stream, making it easy to repeat commands, insert the | |
5639 | arguments to a previous command into the current input line, or | |
5640 | fix errors in previous commands quickly. | |
726f6388 JA |
5641 | .PP |
5642 | History expansion is performed immediately after a complete line | |
5643 | is read, before the shell breaks it into words. | |
ccc6cda3 | 5644 | It takes place in two parts. |
cce855bc | 5645 | The first is to determine which line from the history list |
ccc6cda3 JA |
5646 | to use during substitution. |
5647 | The second is to select portions of that line for inclusion into | |
5648 | the current one. | |
cce855bc | 5649 | The line selected from the history is the \fIevent\fP, |
ccc6cda3 JA |
5650 | and the portions of that line that are acted upon are \fIwords\fP. |
5651 | Various \fImodifiers\fP are available to manipulate the selected words. | |
5652 | The line is broken into words in the same fashion as when reading input, | |
5653 | so that several \fImetacharacter\fP-separated words surrounded by | |
cce855bc | 5654 | quotes are considered one word. |
ccc6cda3 JA |
5655 | History expansions are introduced by the appearance of the |
5656 | history expansion character, which is \^\fB!\fP\^ by default. | |
5657 | Only backslash (\^\fB\e\fP\^) and single quotes can quote | |
5658 | the history expansion character. | |
5659 | .PP | |
d3a24ed2 CR |
5660 | Several characters inhibit history expansion if found immediately |
5661 | following the history expansion character, even if it is unquoted: | |
5662 | space, tab, newline, carriage return, and \fB=\fP. | |
5663 | If the \fBextglob\fP shell option is enabled, \fB(\fP will also | |
5664 | inhibit expansion. | |
5665 | .PP | |
ccc6cda3 JA |
5666 | Several shell options settable with the |
5667 | .B shopt | |
5668 | builtin may be used to tailor the behavior of history expansion. | |
5669 | If the | |
5670 | .B histverify | |
5671 | shell option is enabled (see the description of the | |
5672 | .B shopt | |
5673 | builtin), and | |
5674 | .B readline | |
5675 | is being used, history substitutions are not immediately passed to | |
5676 | the shell parser. | |
5677 | Instead, the expanded line is reloaded into the | |
5678 | .B readline | |
5679 | editing buffer for further modification. | |
5680 | If | |
5681 | .B readline | |
5682 | is being used, and the | |
5683 | .B histreedit | |
5684 | shell option is enabled, a failed history substitution will be reloaded | |
5685 | into the | |
5686 | .B readline | |
5687 | editing buffer for correction. | |
5688 | The | |
5689 | .B \-p | |
5690 | option to the | |
5691 | .B history | |
5692 | builtin command may be used to see what a history expansion will | |
5693 | do before using it. | |
5694 | The | |
5695 | .B \-s | |
5696 | option to the | |
5697 | .B history | |
5698 | builtin may be used to add commands to the end of the history list | |
5699 | without actually executing them, so that they are available for | |
5700 | subsequent recall. | |
726f6388 JA |
5701 | .PP |
5702 | The shell allows control of the various characters used by the | |
5703 | history expansion mechanism (see the description of | |
5704 | .B histchars | |
5705 | above under | |
5706 | .BR "Shell Variables" ). | |
5707 | .SS Event Designators | |
5708 | .PP | |
5709 | An event designator is a reference to a command line entry in the | |
5710 | history list. | |
5711 | .PP | |
5712 | .PD 0 | |
5713 | .TP | |
5714 | .B ! | |
5715 | Start a history substitution, except when followed by a | |
5716 | .BR blank , | |
d3a24ed2 CR |
5717 | newline, carriage return, = |
5718 | or ( (when the \fBextglob\fP shell option is enabled using | |
5719 | the \fBshopt\fP builtin). | |
726f6388 | 5720 | .TP |
726f6388 JA |
5721 | .B !\fIn\fR |
5722 | Refer to command line | |
5723 | .IR n . | |
5724 | .TP | |
5725 | .B !\-\fIn\fR | |
5726 | Refer to the current command line minus | |
5727 | .IR n . | |
5728 | .TP | |
ccc6cda3 JA |
5729 | .B !! |
5730 | Refer to the previous command. This is a synonym for `!\-1'. | |
5731 | .TP | |
726f6388 JA |
5732 | .B !\fIstring\fR |
5733 | Refer to the most recent command starting with | |
5734 | .IR string . | |
5735 | .TP | |
5736 | .B !?\fIstring\fR\fB[?]\fR | |
5737 | Refer to the most recent command containing | |
5738 | .IR string . | |
ccc6cda3 JA |
5739 | The trailing \fB?\fP may be omitted if |
5740 | .I string | |
5741 | is followed immediately by a newline. | |
726f6388 JA |
5742 | .TP |
5743 | .B \d\s+2^\s-2\u\fIstring1\fP\d\s+2^\s-2\u\fIstring2\fP\d\s+2^\s-2\u | |
5744 | Quick substitution. Repeat the last command, replacing | |
5745 | .I string1 | |
5746 | with | |
5747 | .IR string2 . | |
5748 | Equivalent to | |
5749 | ``!!:s/\fIstring1\fP/\fIstring2\fP/'' | |
5750 | (see \fBModifiers\fP below). | |
5751 | .TP | |
5752 | .B !# | |
5753 | The entire command line typed so far. | |
5754 | .PD | |
5755 | .SS Word Designators | |
5756 | .PP | |
ccc6cda3 | 5757 | Word designators are used to select desired words from the event. |
726f6388 JA |
5758 | A |
5759 | .B : | |
ccc6cda3 | 5760 | separates the event specification from the word designator. |
cce855bc | 5761 | It may be omitted if the word designator begins with a |
726f6388 JA |
5762 | .BR ^ , |
5763 | .BR $ , | |
5764 | .BR * , | |
ccc6cda3 | 5765 | .BR \- , |
726f6388 JA |
5766 | or |
5767 | .BR % . | |
5768 | Words are numbered from the beginning of the line, | |
ccc6cda3 JA |
5769 | with the first word being denoted by 0 (zero). |
5770 | Words are inserted into the current line separated by single spaces. | |
726f6388 JA |
5771 | .PP |
5772 | .PD 0 | |
5773 | .TP | |
5774 | .B 0 (zero) | |
5775 | The zeroth word. For the shell, this is the command | |
5776 | word. | |
5777 | .TP | |
5778 | .I n | |
5779 | The \fIn\fRth word. | |
5780 | .TP | |
5781 | .B ^ | |
5782 | The first argument. That is, word 1. | |
5783 | .TP | |
5784 | .B $ | |
5785 | The last argument. | |
5786 | .TP | |
5787 | .B % | |
5788 | The word matched by the most recent `?\fIstring\fR?' search. | |
5789 | .TP | |
5790 | .I x\fB\-\fPy | |
5791 | A range of words; `\-\fIy\fR' abbreviates `0\-\fIy\fR'. | |
5792 | .TP | |
5793 | .B * | |
5794 | All of the words but the zeroth. This is a synonym | |
5795 | for `\fI1\-$\fP'. It is not an error to use | |
5796 | .B * | |
5797 | if there is just one | |
5798 | word in the event; the empty string is returned in that case. | |
5799 | .TP | |
5800 | .B x* | |
5801 | Abbreviates \fIx\-$\fP. | |
5802 | .TP | |
5803 | .B x\- | |
5804 | Abbreviates \fIx\-$\fP like \fBx*\fP, but omits the last word. | |
5805 | .PD | |
ccc6cda3 JA |
5806 | .PP |
5807 | If a word designator is supplied without an event specification, the | |
5808 | previous command is used as the event. | |
726f6388 JA |
5809 | .SS Modifiers |
5810 | .PP | |
ccc6cda3 JA |
5811 | After the optional word designator, there may appear a sequence of |
5812 | one or more of the following modifiers, each preceded by a `:'. | |
726f6388 JA |
5813 | .PP |
5814 | .PD 0 | |
5815 | .PP | |
5816 | .TP | |
5817 | .B h | |
ccc6cda3 JA |
5818 | Remove a trailing file name component, leaving only the head. |
5819 | .TP | |
5820 | .B t | |
5821 | Remove all leading file name components, leaving the tail. | |
726f6388 JA |
5822 | .TP |
5823 | .B r | |
5824 | Remove a trailing suffix of the form \fI.xxx\fP, leaving the | |
5825 | basename. | |
5826 | .TP | |
5827 | .B e | |
5828 | Remove all but the trailing suffix. | |
5829 | .TP | |
726f6388 JA |
5830 | .B p |
5831 | Print the new command but do not execute it. | |
5832 | .TP | |
5833 | .B q | |
5834 | Quote the substituted words, escaping further substitutions. | |
5835 | .TP | |
cce855bc JA |
5836 | .B x |
5837 | Quote the substituted words as with | |
5838 | .BR q , | |
5839 | but break into words at | |
5840 | .B blanks | |
5841 | and newlines. | |
726f6388 | 5842 | .TP |
cce855bc JA |
5843 | .B s/\fIold\fP/\fInew\fP/ |
5844 | Substitute | |
5845 | .I new | |
5846 | for the first occurrence of | |
5847 | .I old | |
5848 | in the event line. Any delimiter can be used in place of /. The | |
5849 | final delimiter is optional if it is the last character of the | |
5850 | event line. The delimiter may be quoted in | |
5851 | .I old | |
5852 | and | |
5853 | .I new | |
5854 | with a single backslash. If & appears in | |
5855 | .IR new , | |
5856 | it is replaced by | |
5857 | .IR old . | |
5858 | A single backslash will quote the &. If | |
5859 | .I old | |
5860 | is null, it is set to the last | |
5861 | .I old | |
5862 | substituted, or, if no previous history substitutions took place, | |
5863 | the last | |
5864 | .I string | |
5865 | in a | |
5866 | .B !?\fIstring\fR\fB[?]\fR | |
5867 | search. | |
ccc6cda3 | 5868 | .TP |
cce855bc JA |
5869 | .B & |
5870 | Repeat the previous substitution. | |
5871 | .TP | |
5872 | .B g | |
5873 | Cause changes to be applied over the entire event line. This is | |
5874 | used in conjunction with `\fB:s\fP' (e.g., `\fB:gs/\fIold\fP/\fInew\fP/\fR') | |
5875 | or `\fB:&\fP'. If used with | |
5876 | `\fB:s\fP', any delimiter can be used | |
5877 | in place of /, and the final delimiter is optional | |
5878 | if it is the last character of the event line. | |
d3a24ed2 CR |
5879 | An \fBa\fP may be used as a synonym for \fBg\fP. |
5880 | .TP | |
5881 | .B G | |
5882 | Apply the following `\fBs\fP' modifier once to each word in the event line. | |
726f6388 | 5883 | .PD |
726f6388 JA |
5884 | .SH "SHELL BUILTIN COMMANDS" |
5885 | .\" start of bash_builtins | |
5886 | .zZ | |
ccc6cda3 JA |
5887 | .PP |
5888 | Unless otherwise noted, each builtin command documented in this | |
5889 | section as accepting options preceded by | |
5890 | .B \- | |
5891 | accepts | |
5892 | .B \-\- | |
5893 | to signify the end of the options. | |
3ffb039a CR |
5894 | For example, the \fB:\fP, \fBtrue\fP, \fBfalse\fP, and \fBtest\fP builtins |
5895 | do not accept options. | |
ccc6cda3 | 5896 | .sp .5 |
726f6388 JA |
5897 | .PD 0 |
5898 | .TP | |
5899 | \fB:\fP [\fIarguments\fP] | |
5900 | .PD | |
5901 | No effect; the command does nothing beyond expanding | |
5902 | .I arguments | |
5903 | and performing any specified | |
5904 | redirections. A zero exit code is returned. | |
5905 | .TP | |
726f6388 | 5906 | \fB .\| \fP \fIfilename\fP [\fIarguments\fP] |
7117c2d2 | 5907 | .PD 0 |
726f6388 JA |
5908 | .TP |
5909 | \fBsource\fP \fIfilename\fP [\fIarguments\fP] | |
5910 | .PD | |
5911 | Read and execute commands from | |
5912 | .I filename | |
5913 | in the current | |
5914 | shell environment and return the exit status of the last command | |
5915 | executed from | |
5916 | .IR filename . | |
5917 | If | |
5918 | .I filename | |
ccc6cda3 | 5919 | does not contain a slash, file names in |
726f6388 JA |
5920 | .SM |
5921 | .B PATH | |
5922 | are used to find the directory containing | |
5923 | .IR filename . | |
5924 | The file searched for in | |
5925 | .SM | |
5926 | .B PATH | |
28ef6c31 JA |
5927 | need not be executable. |
5928 | When \fBbash\fP is not in \fIposix mode\fP, the current directory is | |
726f6388 JA |
5929 | searched if no file is found in |
5930 | .SM | |
5931 | .BR PATH . | |
ccc6cda3 JA |
5932 | If the |
5933 | .B sourcepath | |
5934 | option to the | |
5935 | .B shopt | |
5936 | builtin command is turned off, the | |
5937 | .SM | |
5938 | .B PATH | |
5939 | is not searched. | |
726f6388 | 5940 | If any \fIarguments\fP are supplied, they become the positional |
ccc6cda3 | 5941 | parameters when \fIfilename\fP is executed. Otherwise the positional |
726f6388 JA |
5942 | parameters are unchanged. |
5943 | The return status is the status of the last command exited within | |
5944 | the script (0 if no commands are executed), and false if | |
5945 | .I filename | |
cce855bc | 5946 | is not found or cannot be read. |
726f6388 | 5947 | .TP |
ccc6cda3 JA |
5948 | \fBalias\fP [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP] ...] |
5949 | \fBAlias\fP with no arguments or with the | |
5950 | .B \-p | |
5951 | option prints the list of aliases in the form | |
5952 | \fBalias\fP \fIname\fP=\fIvalue\fP on standard output. | |
5953 | When arguments are supplied, an alias is defined for | |
5954 | each \fIname\fP whose \fIvalue\fP is given. | |
5955 | A trailing space in \fIvalue\fP causes the next word to be | |
5956 | checked for alias substitution when the alias is expanded. | |
5957 | For each \fIname\fP in the argument list for which no \fIvalue\fP | |
5958 | is supplied, the name and value of the alias is printed. | |
5959 | \fBAlias\fP returns true unless a \fIname\fP is given for which | |
5960 | no alias has been defined. | |
726f6388 | 5961 | .TP |
de3341d1 CR |
5962 | \fBbg\fP [\fIjobspec\fP ...] |
5963 | Resume each suspended job \fIjobspec\fP in the background, as if it | |
cce855bc | 5964 | had been started with |
726f6388 JA |
5965 | .BR & . |
5966 | If \fIjobspec\fP is not present, the shell's notion of the | |
5967 | \fIcurrent job\fP is used. | |
5968 | .B bg | |
5969 | .I jobspec | |
5970 | returns 0 unless run when job control is disabled or, when run with | |
de3341d1 CR |
5971 | job control enabled, if the last \fIjobspec\fP was not found or was |
5972 | started without job control. | |
726f6388 | 5973 | .TP |
cce855bc | 5974 | \fBbind\fP [\fB\-m\fP \fIkeymap\fP] [\fB\-lpsvPSV\fP] |
7117c2d2 | 5975 | .PD 0 |
cce855bc JA |
5976 | .TP |
5977 | \fBbind\fP [\fB\-m\fP \fIkeymap\fP] [\fB\-q\fP \fIfunction\fP] [\fB\-u\fP \fIfunction\fP] [\fB\-r\fP \fIkeyseq\fP] | |
726f6388 | 5978 | .TP |
ccc6cda3 | 5979 | \fBbind\fP [\fB\-m\fP \fIkeymap\fP] \fB\-f\fP \fIfilename\fP |
726f6388 | 5980 | .TP |
bb70624e JA |
5981 | \fBbind\fP [\fB\-m\fP \fIkeymap\fP] \fB\-x\fP \fIkeyseq\fP:\fIshell\-command\fP |
5982 | .TP | |
ccc6cda3 | 5983 | \fBbind\fP [\fB\-m\fP \fIkeymap\fP] \fIkeyseq\fP:\fIfunction\-name\fP |
7117c2d2 JA |
5984 | .TP |
5985 | \fBbind\fP \fIreadline\-command\fP | |
726f6388 JA |
5986 | .PD |
5987 | Display current | |
5988 | .B readline | |
7117c2d2 | 5989 | key and function bindings, bind a key sequence to a |
726f6388 | 5990 | .B readline |
7117c2d2 JA |
5991 | function or macro, or set a |
5992 | .B readline | |
5993 | variable. | |
5994 | Each non-option argument is a command as it would appear in | |
726f6388 | 5995 | .IR .inputrc , |
7117c2d2 JA |
5996 | but each binding or command must be passed as a separate argument; |
5997 | e.g., '"\eC\-x\eC\-r": re\-read\-init\-file'. | |
5998 | Options, if supplied, have the following meanings: | |
726f6388 JA |
5999 | .RS |
6000 | .PD 0 | |
6001 | .TP | |
6002 | .B \-m \fIkeymap\fP | |
6003 | Use | |
6004 | .I keymap | |
6005 | as the keymap to be affected by the subsequent bindings. | |
6006 | Acceptable | |
6007 | .I keymap | |
6008 | names are | |
ccc6cda3 | 6009 | \fIemacs, emacs\-standard, emacs\-meta, emacs\-ctlx, vi, |
28ef6c31 | 6010 | vi\-move, vi\-command\fP, and |
ccc6cda3 JA |
6011 | .IR vi\-insert . |
6012 | \fIvi\fP is equivalent to \fIvi\-command\fP; \fIemacs\fP is | |
6013 | equivalent to \fIemacs\-standard\fP. | |
726f6388 JA |
6014 | .TP |
6015 | .B \-l | |
ccc6cda3 JA |
6016 | List the names of all \fBreadline\fP functions. |
6017 | .TP | |
6018 | .B \-p | |
6019 | Display \fBreadline\fP function names and bindings in such a way | |
6020 | that they can be re-read. | |
6021 | .TP | |
6022 | .B \-P | |
6023 | List current \fBreadline\fP function names and bindings. | |
726f6388 JA |
6024 | .TP |
6025 | .B \-v | |
ccc6cda3 JA |
6026 | Display \fBreadline\fP variable names and values in such a way that they |
6027 | can be re-read. | |
726f6388 | 6028 | .TP |
ccc6cda3 JA |
6029 | .B \-V |
6030 | List current \fBreadline\fP variable names and values. | |
6031 | .TP | |
6032 | .B \-s | |
6033 | Display \fBreadline\fP key sequences bound to macros and the strings | |
6034 | they output in such a way that they can be re-read. | |
6035 | .TP | |
6036 | .B \-S | |
6037 | Display \fBreadline\fP key sequences bound to macros and the strings | |
6038 | they output. | |
726f6388 JA |
6039 | .TP |
6040 | .B \-f \fIfilename\fP | |
ccc6cda3 | 6041 | Read key bindings from \fIfilename\fP. |
726f6388 JA |
6042 | .TP |
6043 | .B \-q \fIfunction\fP | |
ccc6cda3 JA |
6044 | Query about which keys invoke the named \fIfunction\fP. |
6045 | .TP | |
cce855bc JA |
6046 | .B \-u \fIfunction\fP |
6047 | Unbind all keys bound to the named \fIfunction\fP. | |
6048 | .TP | |
ccc6cda3 JA |
6049 | .B \-r \fIkeyseq\fP |
6050 | Remove any current binding for \fIkeyseq\fP. | |
bb70624e JA |
6051 | .TP |
6052 | .B \-x \fIkeyseq\fP:\fIshell\-command\fP | |
6053 | Cause \fIshell\-command\fP to be executed whenever \fIkeyseq\fP is | |
6054 | entered. | |
726f6388 JA |
6055 | .PD |
6056 | .PP | |
6057 | The return value is 0 unless an unrecognized option is given or an | |
6058 | error occurred. | |
6059 | .RE | |
6060 | .TP | |
6061 | \fBbreak\fP [\fIn\fP] | |
6062 | Exit from within a | |
6063 | .BR for , | |
6064 | .BR while , | |
ccc6cda3 | 6065 | .BR until , |
726f6388 | 6066 | or |
ccc6cda3 | 6067 | .B select |
726f6388 JA |
6068 | loop. If \fIn\fP is specified, break \fIn\fP levels. |
6069 | .I n | |
6070 | must be \(>= 1. If | |
6071 | .I n | |
6072 | is greater than the number of enclosing loops, all enclosing loops | |
6073 | are exited. The return value is 0 unless the shell is not executing | |
6074 | a loop when | |
6075 | .B break | |
6076 | is executed. | |
6077 | .TP | |
6078 | \fBbuiltin\fP \fIshell\-builtin\fP [\fIarguments\fP] | |
6079 | Execute the specified shell builtin, passing it | |
6080 | .IR arguments , | |
6081 | and return its exit status. | |
cce855bc | 6082 | This is useful when defining a |
726f6388 | 6083 | function whose name is the same as a shell builtin, |
cce855bc JA |
6084 | retaining the functionality of the builtin within the function. |
6085 | The \fBcd\fP builtin is commonly redefined this way. | |
6086 | The return status is false if | |
726f6388 JA |
6087 | .I shell\-builtin |
6088 | is not a shell builtin command. | |
6089 | .TP | |
7117c2d2 | 6090 | \fBcd\fP [\fB\-L|-P\fP] [\fIdir\fP] |
726f6388 JA |
6091 | Change the current directory to \fIdir\fP. The variable |
6092 | .SM | |
6093 | .B HOME | |
6094 | is the | |
6095 | default | |
6096 | .IR dir . | |
6097 | The variable | |
6098 | .SM | |
6099 | .B CDPATH | |
ccc6cda3 | 6100 | defines the search path for the directory containing |
726f6388 | 6101 | .IR dir . |
ccc6cda3 JA |
6102 | Alternative directory names in |
6103 | .SM | |
6104 | .B CDPATH | |
6105 | are separated by a colon (:). A null directory name in | |
726f6388 JA |
6106 | .SM |
6107 | .B CDPATH | |
ccc6cda3 | 6108 | is the same as the current directory, i.e., ``\fB.\fP''. If |
726f6388 JA |
6109 | .I dir |
6110 | begins with a slash (/), | |
6111 | then | |
6112 | .SM | |
6113 | .B CDPATH | |
ccc6cda3 JA |
6114 | is not used. The |
6115 | .B \-P | |
6116 | option says to use the physical directory structure instead of | |
6117 | following symbolic links (see also the | |
6118 | .B \-P | |
6119 | option to the | |
6120 | .B set | |
6121 | builtin command); the | |
6122 | .B \-L | |
6123 | option forces symbolic links to be followed. An argument of | |
726f6388 JA |
6124 | .B \- |
6125 | is equivalent to | |
6126 | .SM | |
6127 | .BR $OLDPWD . | |
d3a24ed2 CR |
6128 | If a non-empty directory name from \fBCDPATH\fP is used, or if |
6129 | \fB\-\fP is the first argument, and the directory change is | |
6130 | successful, the absolute pathname of the new working directory is | |
6131 | written to the standard output. | |
726f6388 JA |
6132 | The return value is true if the directory was successfully changed; |
6133 | false otherwise. | |
6134 | .TP | |
d3a24ed2 CR |
6135 | \fBcaller\fP [\fIexpr\fP] |
6136 | Returns the context of any active subroutine call (a shell function or | |
6137 | a script executed with the \fB.\fP or \fBsource\fP builtins. | |
6138 | Without \fIexpr\fP, \fBcaller\fP displays the line number and source | |
6139 | filename of the current subroutine call. | |
6140 | If a non-negative integer is supplied as \fIexpr\fP, \fBcaller\fP | |
6141 | displays the line number, subroutine name, and source file corresponding | |
6142 | to that position in the current execution call stack. This extra | |
6143 | information may be used, for example, to print a stack trace. The | |
6144 | current frame is frame 0. | |
6145 | The return value is 0 unless the shell is not executing a subroutine | |
6146 | call or \fIexpr\fP does not correspond to a valid position in the | |
6147 | call stack. | |
6148 | .TP | |
ccc6cda3 | 6149 | \fBcommand\fP [\fB\-pVv\fP] \fIcommand\fP [\fIarg\fP ...] |
726f6388 JA |
6150 | Run |
6151 | .I command | |
6152 | with | |
6153 | .I args | |
6154 | suppressing the normal shell function lookup. Only builtin | |
6155 | commands or commands found in the | |
6156 | .SM | |
6157 | .B PATH | |
6158 | are executed. If the | |
6159 | .B \-p | |
6160 | option is given, the search for | |
6161 | .I command | |
6162 | is performed using a default value for | |
6163 | .B PATH | |
6164 | that is guaranteed to find all of the standard utilities. | |
6165 | If either the | |
6166 | .B \-V | |
6167 | or | |
6168 | .B \-v | |
6169 | option is supplied, a description of | |
6170 | .I command | |
6171 | is printed. The | |
6172 | .B \-v | |
ccc6cda3 | 6173 | option causes a single word indicating the command or file name |
726f6388 JA |
6174 | used to invoke |
6175 | .I command | |
cce855bc | 6176 | to be displayed; the |
726f6388 JA |
6177 | .B \-V |
6178 | option produces a more verbose description. | |
726f6388 JA |
6179 | If the |
6180 | .B \-V | |
6181 | or | |
6182 | .B \-v | |
6183 | option is supplied, the exit status is 0 if | |
6184 | .I command | |
6185 | was found, and 1 if not. If neither option is supplied and | |
6186 | an error occurred or | |
6187 | .I command | |
6188 | cannot be found, the exit status is 127. Otherwise, the exit status of the | |
6189 | .B command | |
6190 | builtin is the exit status of | |
6191 | .IR command . | |
6192 | .TP | |
bb70624e JA |
6193 | \fBcompgen\fP [\fIoption\fP] [\fIword\fP] |
6194 | Generate possible completion matches for \fIword\fP according to | |
6195 | the \fIoption\fPs, which may be any option accepted by the | |
6196 | .B complete | |
6197 | builtin with the exception of \fB\-p\fP and \fB\-r\fP, and write | |
6198 | the matches to the standard output. | |
6199 | When using the \fB\-F\fP or \fB\-C\fP options, the various shell variables | |
6200 | set by the programmable completion facilities, while available, will not | |
6201 | have useful values. | |
6202 | .sp 1 | |
6203 | The matches will be generated in the same way as if the programmable | |
6204 | completion code had generated them directly from a completion specification | |
6205 | with the same flags. | |
6206 | If \fIword\fP is specified, only those completions matching \fIword\fP | |
6207 | will be displayed. | |
6208 | .sp 1 | |
6209 | The return value is true unless an invalid option is supplied, or no | |
6210 | matches were generated. | |
6211 | .TP | |
7117c2d2 | 6212 | \fBcomplete\fP [\fB\-abcdefgjksuv\fP] [\fB\-o\fP \fIcomp-option\fP] [\fB\-A\fP \fIaction\fP] [\fB\-G\fP \fIglobpat\fP] [\fB\-W\fP \fIwordlist\fP] [\fB\-P\fP \fIprefix\fP] [\fB\-S\fP \fIsuffix\fP] |
bb70624e JA |
6213 | .br |
6214 | [\fB\-X\fP \fIfilterpat\fP] [\fB\-F\fP \fIfunction\fP] [\fB\-C\fP \fIcommand\fP] \fIname\fP [\fIname ...\fP] | |
7117c2d2 | 6215 | .PD 0 |
bb70624e JA |
6216 | .TP |
6217 | \fBcomplete\fP \fB\-pr\fP [\fIname\fP ...] | |
6218 | .PD | |
6219 | Specify how arguments to each \fIname\fP should be completed. | |
6220 | If the \fB\-p\fP option is supplied, or if no options are supplied, | |
6221 | existing completion specifications are printed in a way that allows | |
6222 | them to be reused as input. | |
6223 | The \fB\-r\fP option removes a completion specification for | |
6224 | each \fIname\fP, or, if no \fIname\fPs are supplied, all | |
6225 | completion specifications. | |
6226 | .sp 1 | |
6227 | The process of applying these completion specifications when word completion | |
6228 | is attempted is described above under \fBProgrammable Completion\fP. | |
6229 | .sp 1 | |
6230 | Other options, if specified, have the following meanings. | |
6231 | The arguments to the \fB\-G\fP, \fB\-W\fP, and \fB\-X\fP options | |
6232 | (and, if necessary, the \fB\-P\fP and \fB\-S\fP options) | |
6233 | should be quoted to protect them from expansion before the | |
6234 | .B complete | |
6235 | builtin is invoked. | |
6236 | .RS | |
6237 | .PD 0 | |
6238 | .TP 8 | |
28ef6c31 JA |
6239 | \fB\-o\fP \fIcomp-option\fP |
6240 | The \fIcomp-option\fP controls several aspects of the compspec's behavior | |
6241 | beyond the simple generation of completions. | |
6242 | \fIcomp-option\fP may be one of: | |
6243 | .RS | |
6244 | .TP 8 | |
d3a24ed2 CR |
6245 | .B bashdefault |
6246 | Perform the rest of the default \fBbash\fP completions if the compspec | |
6247 | generates no matches. | |
6248 | .TP 8 | |
28ef6c31 | 6249 | .B default |
7117c2d2 JA |
6250 | Use readline's default filename completion if the compspec generates |
6251 | no matches. | |
28ef6c31 JA |
6252 | .TP 8 |
6253 | .B dirnames | |
6254 | Perform directory name completion if the compspec generates no matches. | |
6255 | .TP 8 | |
6256 | .B filenames | |
6257 | Tell readline that the compspec generates filenames, so it can perform any | |
6258 | filename\-specific processing (like adding a slash to directory names or | |
6259 | suppressing trailing spaces). Intended to be used with shell functions. | |
7117c2d2 JA |
6260 | .TP 8 |
6261 | .B nospace | |
6262 | Tell readline not to append a space (the default) to words completed at | |
6263 | the end of the line. | |
301e2142 CR |
6264 | .TP 8 |
6265 | .B plusdirs | |
6266 | After any matches defined by the compspec are generated, | |
6267 | directory name completion is attempted and any | |
6268 | matches are added to the results of the other actions. | |
28ef6c31 JA |
6269 | .RE |
6270 | .TP 8 | |
bb70624e JA |
6271 | \fB\-A\fP \fIaction\fP |
6272 | The \fIaction\fP may be one of the following to generate a list of possible | |
6273 | completions: | |
6274 | .RS | |
6275 | .TP 8 | |
6276 | .B alias | |
6277 | Alias names. May also be specified as \fB\-a\fP. | |
6278 | .TP 8 | |
6279 | .B arrayvar | |
6280 | Array variable names. | |
6281 | .TP 8 | |
6282 | .B binding | |
6283 | \fBReadline\fP key binding names. | |
6284 | .TP 8 | |
6285 | .B builtin | |
6286 | Names of shell builtin commands. May also be specified as \fB\-b\fP. | |
6287 | .TP 8 | |
6288 | .B command | |
6289 | Command names. May also be specified as \fB\-c\fP. | |
6290 | .TP 8 | |
6291 | .B directory | |
6292 | Directory names. May also be specified as \fB\-d\fP. | |
6293 | .TP 8 | |
6294 | .B disabled | |
6295 | Names of disabled shell builtins. | |
6296 | .TP 8 | |
6297 | .B enabled | |
6298 | Names of enabled shell builtins. | |
6299 | .TP 8 | |
6300 | .B export | |
6301 | Names of exported shell variables. May also be specified as \fB\-e\fP. | |
6302 | .TP 8 | |
6303 | .B file | |
6304 | File names. May also be specified as \fB\-f\fP. | |
6305 | .TP 8 | |
6306 | .B function | |
6307 | Names of shell functions. | |
6308 | .TP 8 | |
f73dda09 JA |
6309 | .B group |
6310 | Group names. May also be specified as \fB\-g\fP. | |
6311 | .TP 8 | |
bb70624e JA |
6312 | .B helptopic |
6313 | Help topics as accepted by the \fBhelp\fP builtin. | |
6314 | .TP 8 | |
6315 | .B hostname | |
6316 | Hostnames, as taken from the file specified by the | |
6317 | .SM | |
6318 | .B HOSTFILE | |
6319 | shell variable. | |
6320 | .TP 8 | |
6321 | .B job | |
6322 | Job names, if job control is active. May also be specified as \fB\-j\fP. | |
6323 | .TP 8 | |
6324 | .B keyword | |
6325 | Shell reserved words. May also be specified as \fB\-k\fP. | |
6326 | .TP 8 | |
6327 | .B running | |
6328 | Names of running jobs, if job control is active. | |
6329 | .TP 8 | |
7117c2d2 JA |
6330 | .B service |
6331 | Service names. May also be specified as \fB\-s\fP. | |
6332 | .TP 8 | |
bb70624e JA |
6333 | .B setopt |
6334 | Valid arguments for the \fB\-o\fP option to the \fBset\fP builtin. | |
6335 | .TP 8 | |
6336 | .B shopt | |
6337 | Shell option names as accepted by the \fBshopt\fP builtin. | |
6338 | .TP 8 | |
6339 | .B signal | |
6340 | Signal names. | |
6341 | .TP 8 | |
6342 | .B stopped | |
6343 | Names of stopped jobs, if job control is active. | |
6344 | .TP 8 | |
6345 | .B user | |
6346 | User names. May also be specified as \fB\-u\fP. | |
6347 | .TP 8 | |
6348 | .B variable | |
6349 | Names of all shell variables. May also be specified as \fB\-v\fP. | |
6350 | .RE | |
6351 | .TP 8 | |
6352 | \fB\-G\fP \fIglobpat\fP | |
6353 | The filename expansion pattern \fIglobpat\fP is expanded to generate | |
6354 | the possible completions. | |
6355 | .TP 8 | |
6356 | \fB\-W\fP \fIwordlist\fP | |
6357 | The \fIwordlist\fP is split using the characters in the | |
6358 | .SM | |
6359 | .B IFS | |
6360 | special variable as delimiters, and each resultant word is expanded. | |
6361 | The possible completions are the members of the resultant list which | |
6362 | match the word being completed. | |
6363 | .TP 8 | |
6364 | \fB\-C\fP \fIcommand\fP | |
6365 | \fIcommand\fP is executed in a subshell environment, and its output is | |
6366 | used as the possible completions. | |
6367 | .TP 8 | |
6368 | \fB\-F\fP \fIfunction\fP | |
6369 | The shell function \fIfunction\fP is executed in the current shell | |
6370 | environment. | |
6371 | When it finishes, the possible completions are retrieved from the value | |
6372 | of the | |
6373 | .SM | |
6374 | .B COMPREPLY | |
6375 | array variable. | |
6376 | .TP 8 | |
6377 | \fB\-X\fP \fIfilterpat\fP | |
6378 | \fIfilterpat\fP is a pattern as used for filename expansion. | |
6379 | It is applied to the list of possible completions generated by the | |
6380 | preceding options and arguments, and each completion matching | |
6381 | \fIfilterpat\fP is removed from the list. | |
6382 | A leading \fB!\fP in \fIfilterpat\fP negates the pattern; in this | |
6383 | case, any completion not matching \fIfilterpat\fP is removed. | |
6384 | .TP 8 | |
6385 | \fB\-P\fP \fIprefix\fP | |
6386 | \fIprefix\fP is added at the beginning of each possible completion | |
6387 | after all other options have been applied. | |
6388 | .TP 8 | |
6389 | \fB\-S\fP \fIsuffix\fP | |
6390 | \fIsuffix\fP is appended to each possible completion | |
6391 | after all other options have been applied. | |
6392 | .PD | |
6393 | .PP | |
6394 | The return value is true unless an invalid option is supplied, an option | |
6395 | other than \fB\-p\fP or \fB\-r\fP is supplied without a \fIname\fP | |
6396 | argument, an attempt is made to remove a completion specification for | |
6397 | a \fIname\fP for which no specification exists, or | |
6398 | an error occurs adding a completion specification. | |
6399 | .RE | |
6400 | .TP | |
726f6388 JA |
6401 | \fBcontinue\fP [\fIn\fP] |
6402 | Resume the next iteration of the enclosing | |
6403 | .BR for , | |
6404 | .BR while , | |
ccc6cda3 | 6405 | .BR until , |
726f6388 | 6406 | or |
ccc6cda3 | 6407 | .B select |
726f6388 JA |
6408 | loop. |
6409 | If | |
6410 | .I n | |
6411 | is specified, resume at the \fIn\fPth enclosing loop. | |
6412 | .I n | |
6413 | must be \(>= 1. If | |
6414 | .I n | |
6415 | is greater than the number of enclosing loops, the last enclosing loop | |
ccc6cda3 | 6416 | (the ``top-level'' loop) is resumed. The return value is 0 unless the |
726f6388 JA |
6417 | shell is not executing a loop when |
6418 | .B continue | |
6419 | is executed. | |
6420 | .TP | |
d3a24ed2 | 6421 | \fBdeclare\fP [\fB\-afFirtx\fP] [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP] ...] |
726f6388 | 6422 | .PD 0 |
726f6388 | 6423 | .TP |
d3a24ed2 | 6424 | \fBtypeset\fP [\fB\-afFirtx\fP] [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP] ...] |
726f6388 | 6425 | .PD |
ccc6cda3 JA |
6426 | Declare variables and/or give them attributes. |
6427 | If no \fIname\fPs are given then display the values of variables. | |
6428 | The | |
6429 | .B \-p | |
6430 | option will display the attributes and values of each | |
6431 | .IR name . | |
6432 | When | |
6433 | .B \-p | |
6434 | is used, additional options are ignored. | |
6435 | The | |
6436 | .B \-F | |
6437 | option inhibits the display of function definitions; only the | |
6438 | function name and attributes are printed. | |
d3a24ed2 CR |
6439 | If the \fBextdebug\fP shell option is enabled using \fBshopt\fP, |
6440 | the source file name and line number where the function is defined | |
6441 | are displayed as well. The | |
ccc6cda3 JA |
6442 | .B \-F |
6443 | option implies | |
6444 | .BR \-f . | |
6445 | The following options can | |
6446 | be used to restrict output to variables with the specified attribute or | |
6447 | to give variables attributes: | |
726f6388 JA |
6448 | .RS |
6449 | .PD 0 | |
6450 | .TP | |
ccc6cda3 JA |
6451 | .B \-a |
6452 | Each \fIname\fP is an array variable (see | |
6453 | .B Arrays | |
6454 | above). | |
6455 | .TP | |
726f6388 | 6456 | .B \-f |
ccc6cda3 JA |
6457 | Use function names only. |
6458 | .TP | |
6459 | .B \-i | |
6460 | The variable is treated as an integer; arithmetic evaluation (see | |
6461 | .SM | |
6462 | .B "ARITHMETIC EVALUATION" ") " | |
6463 | is performed when the variable is assigned a value. | |
726f6388 JA |
6464 | .TP |
6465 | .B \-r | |
6466 | Make \fIname\fPs readonly. These names cannot then be assigned values | |
cce855bc | 6467 | by subsequent assignment statements or unset. |
726f6388 | 6468 | .TP |
7117c2d2 JA |
6469 | .B \-t |
6470 | Give each \fIname\fP the \fItrace\fP attribute. | |
76a8d78d CR |
6471 | Traced functions inherit the \fBDEBUG\fP and \fBRETURN\fP traps from |
6472 | the calling shell. | |
7117c2d2 JA |
6473 | The trace attribute has no special meaning for variables. |
6474 | .TP | |
726f6388 JA |
6475 | .B \-x |
6476 | Mark \fIname\fPs for export to subsequent commands via the environment. | |
726f6388 JA |
6477 | .PD |
6478 | .PP | |
6479 | Using `+' instead of `\-' | |
ccc6cda3 JA |
6480 | turns off the attribute instead, with the exception that \fB+a\fP |
6481 | may not be used to destroy an array variable. When used in a function, | |
6482 | makes each | |
6483 | \fIname\fP local, as with the | |
726f6388 | 6484 | .B local |
d3a24ed2 CR |
6485 | command. |
6486 | If a variable name is followed by =\fIvalue\fP, the value of | |
6487 | the variable is set to \fIvalue\fP. | |
6488 | The return value is 0 unless an invalid option is encountered, | |
bb70624e JA |
6489 | an attempt is made to define a function using |
6490 | .if n ``\-f foo=bar'', | |
6491 | .if t \f(CW\-f foo=bar\fP, | |
ccc6cda3 JA |
6492 | an attempt is made to assign a value to a readonly variable, |
6493 | an attempt is made to assign a value to an array variable without | |
6494 | using the compound assignment syntax (see | |
6495 | .B Arrays | |
cce855bc | 6496 | above), one of the \fInames\fP is not a valid shell variable name, |
726f6388 | 6497 | an attempt is made to turn off readonly status for a readonly variable, |
ccc6cda3 | 6498 | an attempt is made to turn off array status for an array variable, |
bb70624e | 6499 | or an attempt is made to display a non-existent function with \fB\-f\fP. |
726f6388 JA |
6500 | .RE |
6501 | .TP | |
ccc6cda3 JA |
6502 | .B dirs [\fB\-clpv\fP] [+\fIn\fP] [\-\fIn\fP] |
6503 | Without options, displays the list of currently remembered directories. | |
6504 | The default display is on a single line with directory names separated | |
6505 | by spaces. | |
6506 | Directories are added to the list with the | |
726f6388 JA |
6507 | .B pushd |
6508 | command; the | |
6509 | .B popd | |
ccc6cda3 | 6510 | command removes entries from the list. |
726f6388 JA |
6511 | .RS |
6512 | .PD 0 | |
6513 | .TP | |
ccc6cda3 JA |
6514 | \fB+\fP\fIn\fP |
6515 | Displays the \fIn\fPth entry counting from the left of the list | |
726f6388 JA |
6516 | shown by |
6517 | .B dirs | |
6518 | when invoked without options, starting with zero. | |
6519 | .TP | |
ccc6cda3 JA |
6520 | \fB\-\fP\fIn\fP |
6521 | Displays the \fIn\fPth entry counting from the right of the list | |
726f6388 JA |
6522 | shown by |
6523 | .B dirs | |
6524 | when invoked without options, starting with zero. | |
6525 | .TP | |
ccc6cda3 JA |
6526 | .B \-c |
6527 | Clears the directory stack by deleting all of the entries. | |
6528 | .TP | |
726f6388 | 6529 | .B \-l |
ccc6cda3 | 6530 | Produces a longer listing; the default listing format uses a |
726f6388 | 6531 | tilde to denote the home directory. |
ccc6cda3 JA |
6532 | .TP |
6533 | .B \-p | |
6534 | Print the directory stack with one entry per line. | |
6535 | .TP | |
6536 | .B \-v | |
6537 | Print the directory stack with one entry per line, | |
6538 | prefixing each entry with its index in the stack. | |
726f6388 JA |
6539 | .PD |
6540 | .PP | |
6541 | The return value is 0 unless an | |
cce855bc | 6542 | invalid option is supplied or \fIn\fP indexes beyond the end |
726f6388 JA |
6543 | of the directory stack. |
6544 | .RE | |
6545 | .TP | |
cce855bc | 6546 | \fBdisown\fP [\fB\-ar\fP] [\fB\-h\fP] [\fIjobspec\fP ...] |
ccc6cda3 JA |
6547 | Without options, each |
6548 | .I jobspec | |
6549 | is removed from the table of active jobs. | |
cce855bc JA |
6550 | If the \fB\-h\fP option is given, each |
6551 | .I jobspec | |
6552 | is not removed from the table, but is marked so that | |
ccc6cda3 JA |
6553 | .SM |
6554 | .B SIGHUP | |
6555 | is not sent to the job if the shell receives a | |
6556 | .SM | |
6557 | .BR SIGHUP . | |
6558 | If no | |
6559 | .I jobspec | |
cce855bc JA |
6560 | is present, and neither the |
6561 | .B \-a | |
6562 | nor the | |
6563 | .B \-r | |
6564 | option is supplied, the \fIcurrent job\fP is used. | |
6565 | If no | |
6566 | .I jobspec | |
6567 | is supplied, the | |
6568 | .B \-a | |
6569 | option means to remove or mark all jobs; the | |
6570 | .B \-r | |
6571 | option without a | |
6572 | .I jobspec | |
6573 | argument restricts operation to running jobs. | |
6574 | The return value is 0 unless a | |
ccc6cda3 JA |
6575 | .I jobspec |
6576 | does not specify a valid job. | |
6577 | .TP | |
726f6388 | 6578 | \fBecho\fP [\fB\-neE\fP] [\fIarg\fP ...] |
ccc6cda3 JA |
6579 | Output the \fIarg\fPs, separated by spaces, followed by a newline. |
6580 | The return status is always 0. | |
6581 | If \fB\-n\fP is specified, the trailing newline is | |
726f6388 JA |
6582 | suppressed. If the \fB\-e\fP option is given, interpretation of |
6583 | the following backslash-escaped characters is enabled. The | |
6584 | .B \-E | |
6585 | option disables the interpretation of these escape characters, | |
6586 | even on systems where they are interpreted by default. | |
28ef6c31 | 6587 | The \fBxpg_echo\fP shell option may be used to |
bb70624e JA |
6588 | dynamically determine whether or not \fBecho\fP expands these |
6589 | escape characters by default. | |
ccc6cda3 | 6590 | .B echo |
3ffb039a | 6591 | does not interpret \fB\-\-\fP to mean the end of options. |
ccc6cda3 JA |
6592 | .B echo |
6593 | interprets the following escape sequences: | |
726f6388 JA |
6594 | .RS |
6595 | .PD 0 | |
6596 | .TP | |
6597 | .B \ea | |
6598 | alert (bell) | |
6599 | .TP | |
6600 | .B \eb | |
6601 | backspace | |
6602 | .TP | |
6603 | .B \ec | |
6604 | suppress trailing newline | |
6605 | .TP | |
ccc6cda3 JA |
6606 | .B \ee |
6607 | an escape character | |
6608 | .TP | |
726f6388 JA |
6609 | .B \ef |
6610 | form feed | |
6611 | .TP | |
6612 | .B \en | |
6613 | new line | |
6614 | .TP | |
6615 | .B \er | |
6616 | carriage return | |
6617 | .TP | |
6618 | .B \et | |
6619 | horizontal tab | |
6620 | .TP | |
6621 | .B \ev | |
6622 | vertical tab | |
6623 | .TP | |
6624 | .B \e\e | |
6625 | backslash | |
6626 | .TP | |
7117c2d2 JA |
6627 | .B \e0\fInnn\fP |
6628 | the eight-bit character whose value is the octal value \fInnn\fP | |
6629 | (zero to three octal digits) | |
6630 | .TP | |
cce855bc | 6631 | .B \e\fInnn\fP |
f73dda09 | 6632 | the eight-bit character whose value is the octal value \fInnn\fP |
7117c2d2 | 6633 | (one to three octal digits) |
cce855bc | 6634 | .TP |
f73dda09 JA |
6635 | .B \ex\fIHH\fP |
6636 | the eight-bit character whose value is the hexadecimal value \fIHH\fP | |
6637 | (one or two hex digits) | |
726f6388 JA |
6638 | .PD |
6639 | .RE | |
6640 | .TP | |
ccc6cda3 | 6641 | \fBenable\fP [\fB\-adnps\fP] [\fB\-f\fP \fIfilename\fP] [\fIname\fP ...] |
cce855bc JA |
6642 | Enable and disable builtin shell commands. |
6643 | Disabling a builtin allows a disk command which has the same name | |
bb70624e | 6644 | as a shell builtin to be executed without specifying a full pathname, |
cce855bc | 6645 | even though the shell normally searches for builtins before disk commands. |
726f6388 JA |
6646 | If \fB\-n\fP is used, each \fIname\fP |
6647 | is disabled; otherwise, | |
6648 | \fInames\fP are enabled. For example, to use the | |
6649 | .B test | |
6650 | binary found via the | |
6651 | .SM | |
6652 | .B PATH | |
ccc6cda3 | 6653 | instead of the shell builtin version, run |
28ef6c31 JA |
6654 | .if t \f(CWenable -n test\fP. |
6655 | .if n ``enable -n test''. | |
ccc6cda3 JA |
6656 | The |
6657 | .B \-f | |
6658 | option means to load the new builtin command | |
6659 | .I name | |
6660 | from shared object | |
6661 | .IR filename , | |
6662 | on systems that support dynamic loading. The | |
6663 | .B \-d | |
6664 | option will delete a builtin previously loaded with | |
6665 | .BR \-f . | |
6666 | If no \fIname\fP arguments are given, or if the | |
6667 | .B \-p | |
6668 | option is supplied, a list of shell builtins is printed. | |
6669 | With no other option arguments, the list consists of all enabled | |
6670 | shell builtins. | |
6671 | If \fB\-n\fP is supplied, only disabled builtins are printed. | |
6672 | If \fB\-a\fP is supplied, the list printed includes all builtins, with an | |
726f6388 | 6673 | indication of whether or not each is enabled. |
ccc6cda3 JA |
6674 | If \fB\-s\fP is supplied, the output is restricted to the POSIX |
6675 | \fIspecial\fP builtins. | |
726f6388 JA |
6676 | The return value is 0 unless a |
6677 | .I name | |
bb70624e | 6678 | is not a shell builtin or there is an error loading a new builtin |
ccc6cda3 | 6679 | from a shared object. |
726f6388 JA |
6680 | .TP |
6681 | \fBeval\fP [\fIarg\fP ...] | |
6682 | The \fIarg\fPs are read and concatenated together into a single | |
6683 | command. This command is then read and executed by the shell, and | |
ccc6cda3 JA |
6684 | its exit status is returned as the value of |
6685 | .BR eval . | |
6686 | If there are no | |
726f6388 JA |
6687 | .IR args , |
6688 | or only null arguments, | |
6689 | .B eval | |
ccc6cda3 | 6690 | returns 0. |
726f6388 | 6691 | .TP |
cce855bc | 6692 | \fBexec\fP [\fB\-cl\fP] [\fB\-a\fP \fIname\fP] [\fIcommand\fP [\fIarguments\fP]] |
726f6388 JA |
6693 | If |
6694 | .I command | |
6695 | is specified, it replaces the shell. | |
6696 | No new process is created. The | |
6697 | .I arguments | |
6698 | become the arguments to \fIcommand\fP. | |
ccc6cda3 JA |
6699 | If the |
6700 | .B \-l | |
6701 | option is supplied, | |
bb70624e | 6702 | the shell places a dash at the beginning of the zeroth arg passed to |
726f6388 | 6703 | .IR command . |
ccc6cda3 JA |
6704 | This is what |
6705 | .IR login (1) | |
6706 | does. The | |
6707 | .B \-c | |
6708 | option causes | |
6709 | .I command | |
6710 | to be executed with an empty environment. If | |
6711 | .B \-a | |
6712 | is supplied, the shell passes | |
6713 | .I name | |
6714 | as the zeroth argument to the executed command. If | |
6715 | .I command | |
726f6388 | 6716 | cannot be executed for some reason, a non-interactive shell exits, |
ccc6cda3 JA |
6717 | unless the shell option |
6718 | .B execfail | |
6719 | is enabled, in which case it returns failure. | |
6720 | An interactive shell returns failure if the file cannot be executed. | |
726f6388 JA |
6721 | If |
6722 | .I command | |
6723 | is not specified, any redirections take effect in the current shell, | |
cce855bc JA |
6724 | and the return status is 0. If there is a redirection error, the |
6725 | return status is 1. | |
726f6388 JA |
6726 | .TP |
6727 | \fBexit\fP [\fIn\fP] | |
6728 | Cause the shell to exit | |
6729 | with a status of \fIn\fP. If | |
6730 | .I n | |
6731 | is omitted, the exit status | |
6732 | is that of the last command executed. | |
6733 | A trap on | |
6734 | .SM | |
6735 | .B EXIT | |
6736 | is executed before the shell terminates. | |
6737 | .TP | |
ccc6cda3 | 6738 | \fBexport\fP [\fB\-fn\fP\^] [\fIname\fP[=\fIword\fP]] ... |
7117c2d2 | 6739 | .PD 0 |
726f6388 JA |
6740 | .TP |
6741 | .B export \-p | |
6742 | .PD | |
6743 | The supplied | |
6744 | .I names | |
6745 | are marked for automatic export to the environment of | |
6746 | subsequently executed commands. If the | |
6747 | .B \-f | |
6748 | option is given, | |
6749 | the | |
6750 | .I names | |
6751 | refer to functions. | |
6752 | If no | |
6753 | .I names | |
6754 | are given, or if the | |
6755 | .B \-p | |
6756 | option is supplied, a list | |
6757 | of all names that are exported in this shell is printed. | |
6758 | The | |
6759 | .B \-n | |
5e13499c CR |
6760 | option causes the export property to be removed from each |
6761 | \fIname\fP. | |
d3a24ed2 CR |
6762 | If a variable name is followed by =\fIword\fP, the value of |
6763 | the variable is set to \fIword\fP. | |
726f6388 | 6764 | .B export |
cce855bc | 6765 | returns an exit status of 0 unless an invalid option is |
726f6388 | 6766 | encountered, |
cce855bc | 6767 | one of the \fInames\fP is not a valid shell variable name, or |
726f6388 JA |
6768 | .B \-f |
6769 | is supplied with a | |
6770 | .I name | |
6771 | that is not a function. | |
6772 | .TP | |
726f6388 | 6773 | \fBfc\fP [\fB\-e\fP \fIename\fP] [\fB\-nlr\fP] [\fIfirst\fP] [\fIlast\fP] |
7117c2d2 | 6774 | .PD 0 |
726f6388 JA |
6775 | .TP |
6776 | \fBfc\fP \fB\-s\fP [\fIpat\fP=\fIrep\fP] [\fIcmd\fP] | |
6777 | .PD | |
6778 | Fix Command. In the first form, a range of commands from | |
6779 | .I first | |
6780 | to | |
6781 | .I last | |
6782 | is selected from the history list. | |
6783 | .I First | |
6784 | and | |
6785 | .I last | |
6786 | may be specified as a string (to locate the last command beginning | |
6787 | with that string) or as a number (an index into the history list, | |
6788 | where a negative number is used as an offset from the current | |
6789 | command number). If | |
6790 | .I last | |
6791 | is not specified it is set to | |
6792 | the current command for listing (so that | |
bb70624e JA |
6793 | .if n ``fc \-l \-10'' |
6794 | .if t \f(CWfc \-l \-10\fP | |
726f6388 JA |
6795 | prints the last 10 commands) and to |
6796 | .I first | |
6797 | otherwise. | |
6798 | If | |
6799 | .I first | |
6800 | is not specified it is set to the previous | |
6801 | command for editing and \-16 for listing. | |
6802 | .sp 1 | |
6803 | The | |
6804 | .B \-n | |
cce855bc | 6805 | option suppresses |
726f6388 JA |
6806 | the command numbers when listing. The |
6807 | .B \-r | |
cce855bc | 6808 | option reverses the order of |
726f6388 JA |
6809 | the commands. If the |
6810 | .B \-l | |
cce855bc | 6811 | option is given, |
726f6388 JA |
6812 | the commands are listed on |
6813 | standard output. Otherwise, the editor given by | |
6814 | .I ename | |
6815 | is invoked | |
6816 | on a file containing those commands. If | |
6817 | .I ename | |
6818 | is not given, the | |
6819 | value of the | |
6820 | .SM | |
6821 | .B FCEDIT | |
6822 | variable is used, and | |
6823 | the value of | |
6824 | .SM | |
6825 | .B EDITOR | |
6826 | if | |
6827 | .SM | |
6828 | .B FCEDIT | |
6829 | is not set. If neither variable is set, | |
6830 | .FN vi | |
6831 | is used. When editing is complete, the edited commands are | |
6832 | echoed and executed. | |
6833 | .sp 1 | |
6834 | In the second form, \fIcommand\fP is re-executed after each instance | |
6835 | of \fIpat\fP is replaced by \fIrep\fP. | |
ccc6cda3 | 6836 | A useful alias to use with this is |
d3a24ed2 | 6837 | .if n ``r="fc -s"'', |
ccc6cda3 JA |
6838 | .if t \f(CWr='fc \-s'\fP, |
6839 | so that typing | |
6840 | .if n ``r cc'' | |
6841 | .if t \f(CWr cc\fP | |
6842 | runs the last command beginning with | |
6843 | .if n ``cc'' | |
6844 | .if t \f(CWcc\fP | |
6845 | and typing | |
6846 | .if n ``r'' | |
6847 | .if t \f(CWr\fP | |
726f6388 JA |
6848 | re-executes the last command. |
6849 | .sp 1 | |
cce855bc | 6850 | If the first form is used, the return value is 0 unless an invalid |
726f6388 JA |
6851 | option is encountered or |
6852 | .I first | |
6853 | or | |
6854 | .I last | |
6855 | specify history lines out of range. | |
6856 | If the | |
6857 | .B \-e | |
6858 | option is supplied, the return value is the value of the last | |
6859 | command executed or failure if an error occurs with the temporary | |
6860 | file of commands. If the second form is used, the return status | |
6861 | is that of the command re-executed, unless | |
6862 | .I cmd | |
6863 | does not specify a valid history line, in which case | |
6864 | .B fc | |
6865 | returns failure. | |
6866 | .TP | |
6867 | \fBfg\fP [\fIjobspec\fP] | |
cce855bc | 6868 | Resume |
726f6388 | 6869 | .I jobspec |
cce855bc JA |
6870 | in the foreground, and make it the current job. |
6871 | If | |
726f6388 JA |
6872 | .I jobspec |
6873 | is not present, the shell's notion of the \fIcurrent job\fP is used. | |
6874 | The return value is that of the command placed into the foreground, | |
6875 | or failure if run when job control is disabled or, when run with | |
6876 | job control enabled, if | |
6877 | .I jobspec | |
6878 | does not specify a valid job or | |
6879 | .I jobspec | |
6880 | specifies a job that was started without job control. | |
6881 | .TP | |
6882 | \fBgetopts\fP \fIoptstring\fP \fIname\fP [\fIargs\fP] | |
6883 | .B getopts | |
6884 | is used by shell procedures to parse positional parameters. | |
6885 | .I optstring | |
bb70624e | 6886 | contains the option characters to be recognized; if a character |
726f6388 JA |
6887 | is followed by a colon, the option is expected to have an |
6888 | argument, which should be separated from it by white space. | |
bb70624e JA |
6889 | The colon and question mark characters may not be used as |
6890 | option characters. | |
726f6388 JA |
6891 | Each time it is invoked, |
6892 | .B getopts | |
6893 | places the next option in the shell variable | |
6894 | .IR name , | |
6895 | initializing | |
6896 | .I name | |
6897 | if it does not exist, | |
6898 | and the index of the next argument to be processed into the | |
6899 | variable | |
6900 | .SM | |
6901 | .BR OPTIND . | |
6902 | .SM | |
6903 | .B OPTIND | |
6904 | is initialized to 1 each time the shell or a shell script | |
6905 | is invoked. When an option requires an argument, | |
6906 | .B getopts | |
6907 | places that argument into the variable | |
6908 | .SM | |
6909 | .BR OPTARG . | |
6910 | The shell does not reset | |
6911 | .SM | |
6912 | .B OPTIND | |
6913 | automatically; it must be manually reset between multiple | |
6914 | calls to | |
6915 | .B getopts | |
6916 | within the same shell invocation if a new set of parameters | |
6917 | is to be used. | |
6918 | .sp 1 | |
cce855bc JA |
6919 | When the end of options is encountered, \fBgetopts\fP exits with a |
6920 | return value greater than zero. | |
6921 | \fBOPTIND\fP is set to the index of the first non-option argument, | |
6922 | and \fBname\fP is set to ?. | |
6923 | .sp 1 | |
6924 | .B getopts | |
6925 | normally parses the positional parameters, but if more arguments are | |
6926 | given in | |
6927 | .IR args , | |
6928 | .B getopts | |
6929 | parses those instead. | |
6930 | .sp 1 | |
726f6388 JA |
6931 | .B getopts |
6932 | can report errors in two ways. If the first character of | |
6933 | .I optstring | |
6934 | is a colon, | |
6935 | .I silent | |
6936 | error reporting is used. In normal operation diagnostic messages | |
cce855bc | 6937 | are printed when invalid options or missing option arguments are |
726f6388 JA |
6938 | encountered. |
6939 | If the variable | |
6940 | .SM | |
6941 | .B OPTERR | |
cce855bc | 6942 | is set to 0, no error messages will be displayed, even if the first |
726f6388 JA |
6943 | character of |
6944 | .I optstring | |
6945 | is not a colon. | |
6946 | .sp 1 | |
cce855bc | 6947 | If an invalid option is seen, |
726f6388 JA |
6948 | .B getopts |
6949 | places ? into | |
6950 | .I name | |
6951 | and, if not silent, | |
6952 | prints an error message and unsets | |
6953 | .SM | |
6954 | .BR OPTARG . | |
6955 | If | |
6956 | .B getopts | |
6957 | is silent, | |
6958 | the option character found is placed in | |
6959 | .SM | |
6960 | .B OPTARG | |
6961 | and no diagnostic message is printed. | |
6962 | .sp 1 | |
6963 | If a required argument is not found, and | |
6964 | .B getopts | |
6965 | is not silent, | |
6966 | a question mark (\^\fB?\fP\^) is placed in | |
6967 | .IR name , | |
f73dda09 | 6968 | .SM |
726f6388 JA |
6969 | .B OPTARG |
6970 | is unset, and a diagnostic message is printed. | |
6971 | If | |
6972 | .B getopts | |
6973 | is silent, then a colon (\^\fB:\fP\^) is placed in | |
6974 | .I name | |
6975 | and | |
6976 | .SM | |
6977 | .B OPTARG | |
6978 | is set to the option character found. | |
6979 | .sp 1 | |
6980 | .B getopts | |
726f6388 JA |
6981 | returns true if an option, specified or unspecified, is found. |
6982 | It returns false if the end of options is encountered or an | |
6983 | error occurs. | |
6984 | .TP | |
7117c2d2 | 6985 | \fBhash\fP [\fB\-lr\fP] [\fB\-p\fP \fIfilename\fP] [\fB\-dt\fP] [\fIname\fP] |
726f6388 JA |
6986 | For each |
6987 | .IR name , | |
ccc6cda3 JA |
6988 | the full file name of the command is determined by searching |
6989 | the directories in | |
6990 | .B $PATH | |
6991 | and remembered. | |
6992 | If the | |
6993 | .B \-p | |
6994 | option is supplied, no path search is performed, and | |
6995 | .I filename | |
6996 | is used as the full file name of the command. | |
6997 | The | |
726f6388 JA |
6998 | .B \-r |
6999 | option causes the shell to forget all | |
f73dda09 | 7000 | remembered locations. |
7117c2d2 JA |
7001 | The |
7002 | .B \-d | |
7003 | option causes the shell to forget the remembered location of each \fIname\fP. | |
f73dda09 JA |
7004 | If the |
7005 | .B \-t | |
7006 | option is supplied, the full pathname to which each \fIname\fP corresponds | |
7007 | is printed. If multiple \fIname\fP arguments are supplied with \fB\-t\fP, | |
7008 | the \fIname\fP is printed before the hashed full pathname. | |
7117c2d2 JA |
7009 | The |
7010 | .B \-l | |
7011 | option causes output to be displayed in a format that may be reused as input. | |
7012 | If no arguments are given, or if only \fB\-l\fP is supplied, | |
7013 | information about remembered commands is printed. | |
ccc6cda3 | 7014 | The return status is true unless a |
726f6388 | 7015 | .I name |
cce855bc | 7016 | is not found or an invalid option is supplied. |
726f6388 | 7017 | .TP |
bb70624e | 7018 | \fBhelp\fP [\fB\-s\fP] [\fIpattern\fP] |
726f6388 JA |
7019 | Display helpful information about builtin commands. If |
7020 | .I pattern | |
7021 | is specified, | |
7022 | .B help | |
7023 | gives detailed help on all commands matching | |
7024 | .IR pattern ; | |
ccc6cda3 | 7025 | otherwise help for all the builtins and shell control structures |
bb70624e JA |
7026 | is printed. |
7027 | The \fB\-s\fP option restricts the information displayed to a short | |
7028 | usage synopsis. | |
7029 | The return status is 0 unless no command matches | |
726f6388 JA |
7030 | .IR pattern . |
7031 | .TP | |
bb70624e | 7032 | \fBhistory [\fIn\fP] |
7117c2d2 | 7033 | .PD 0 |
bb70624e JA |
7034 | .TP |
7035 | \fBhistory\fP \fB\-c\fP | |
7036 | .TP | |
7037 | \fBhistory \-d\fP \fIoffset\fP | |
ccc6cda3 JA |
7038 | .TP |
7039 | \fBhistory\fP \fB\-anrw\fP [\fIfilename\fP] | |
726f6388 | 7040 | .TP |
ccc6cda3 JA |
7041 | \fBhistory\fP \fB\-p\fP \fIarg\fP [\fIarg ...\fP] |
7042 | .TP | |
7043 | \fBhistory\fP \fB\-s\fP \fIarg\fP [\fIarg ...\fP] | |
726f6388 JA |
7044 | .PD |
7045 | With no options, display the command | |
7046 | history list with line numbers. Lines listed | |
7047 | with a | |
7048 | .B * | |
7049 | have been modified. An argument of | |
7050 | .I n | |
7051 | lists only the last | |
7052 | .I n | |
d3a24ed2 CR |
7053 | lines. |
7054 | If the shell variable \fBHISTTIMEFORMAT\fP is set and not null, | |
7055 | it is used as a format string for \fIstrftime\fP(3) to display | |
7056 | the time stamp associated with each displayed history entry. | |
7057 | No intervening blank is printed between the formatted time stamp | |
7058 | and the history line. | |
7059 | If \fIfilename\fP is supplied, it is used as the | |
726f6388 JA |
7060 | name of the history file; if not, the value of |
7061 | .SM | |
7062 | .B HISTFILE | |
7063 | is used. Options, if supplied, have the following meanings: | |
7064 | .RS | |
7065 | .PD 0 | |
7066 | .TP | |
bb70624e JA |
7067 | .B \-c |
7068 | Clear the history list by deleting all the entries. | |
7069 | .TP | |
7070 | \fB\-d\fP \fIoffset\fP | |
7071 | Delete the history entry at position \fIoffset\fP. | |
7072 | .TP | |
726f6388 JA |
7073 | .B \-a |
7074 | Append the ``new'' history lines (history lines entered since the | |
ccc6cda3 | 7075 | beginning of the current \fBbash\fP session) to the history file. |
726f6388 JA |
7076 | .TP |
7077 | .B \-n | |
7078 | Read the history lines not already read from the history | |
7079 | file into the current history list. These are lines | |
7080 | appended to the history file since the beginning of the | |
7081 | current \fBbash\fP session. | |
7082 | .TP | |
7083 | .B \-r | |
7084 | Read the contents of the history file | |
ccc6cda3 | 7085 | and use them as the current history. |
726f6388 JA |
7086 | .TP |
7087 | .B \-w | |
7088 | Write the current history to the history file, overwriting the | |
7089 | history file's contents. | |
ccc6cda3 | 7090 | .TP |
ccc6cda3 JA |
7091 | .B \-p |
7092 | Perform history substitution on the following \fIargs\fP and display | |
7093 | the result on the standard output. | |
7094 | Does not store the results in the history list. | |
7095 | Each \fIarg\fP must be quoted to disable normal history expansion. | |
7096 | .TP | |
7097 | .B \-s | |
7098 | Store the | |
7099 | .I args | |
7100 | in the history list as a single entry. The last command in the | |
7101 | history list is removed before the | |
7102 | .I args | |
7103 | are added. | |
726f6388 JA |
7104 | .PD |
7105 | .PP | |
d3a24ed2 CR |
7106 | If the \fBHISTTIMEFORMAT\fP is set, the time stamp information |
7107 | associated with each history entry is written to the history file. | |
bb70624e JA |
7108 | The return value is 0 unless an invalid option is encountered, an |
7109 | error occurs while reading or writing the history file, an invalid | |
7110 | \fIoffset\fP is supplied as an argument to \fB\-d\fP, or the | |
7111 | history expansion supplied as an argument to \fB\-p\fP fails. | |
726f6388 JA |
7112 | .RE |
7113 | .TP | |
ccc6cda3 | 7114 | \fBjobs\fP [\fB\-lnprs\fP] [ \fIjobspec\fP ... ] |
7117c2d2 | 7115 | .PD 0 |
726f6388 JA |
7116 | .TP |
7117 | \fBjobs\fP \fB\-x\fP \fIcommand\fP [ \fIargs\fP ... ] | |
7118 | .PD | |
ccc6cda3 JA |
7119 | The first form lists the active jobs. The options have the following |
7120 | meanings: | |
7121 | .RS | |
7122 | .PD 0 | |
7123 | .TP | |
726f6388 | 7124 | .B \-l |
ccc6cda3 JA |
7125 | List process IDs |
7126 | in addition to the normal information. | |
7127 | .TP | |
726f6388 | 7128 | .B \-p |
ccc6cda3 JA |
7129 | List only the process ID of the job's process group |
7130 | leader. | |
7131 | .TP | |
726f6388 | 7132 | .B \-n |
ccc6cda3 JA |
7133 | Display information only about jobs that have changed status since |
7134 | the user was last notified of their status. | |
7135 | .TP | |
7136 | .B \-r | |
7137 | Restrict output to running jobs. | |
7138 | .TP | |
7139 | .B \-s | |
7140 | Restrict output to stopped jobs. | |
7141 | .PD | |
7142 | .PP | |
7143 | If | |
726f6388 JA |
7144 | .I jobspec |
7145 | is given, output is restricted to information about that job. | |
cce855bc JA |
7146 | The return status is 0 unless an invalid option is encountered |
7147 | or an invalid | |
726f6388 JA |
7148 | .I jobspec |
7149 | is supplied. | |
ccc6cda3 | 7150 | .PP |
726f6388 JA |
7151 | If the |
7152 | .B \-x | |
7153 | option is supplied, | |
7154 | .B jobs | |
7155 | replaces any | |
7156 | .I jobspec | |
7157 | found in | |
7158 | .I command | |
7159 | or | |
7160 | .I args | |
7161 | with the corresponding process group ID, and executes | |
7162 | .I command | |
7163 | passing it | |
7164 | .IR args , | |
7165 | returning its exit status. | |
ccc6cda3 | 7166 | .RE |
726f6388 | 7167 | .TP |
ccc6cda3 | 7168 | \fBkill\fP [\fB\-s\fP \fIsigspec\fP | \fB\-n\fP \fIsignum\fP | \fB\-\fP\fIsigspec\fP] [\fIpid\fP | \fIjobspec\fP] ... |
7117c2d2 | 7169 | .PD 0 |
726f6388 | 7170 | .TP |
cce855bc | 7171 | \fBkill\fP \fB\-l\fP [\fIsigspec\fP | \fIexit_status\fP] |
726f6388 JA |
7172 | .PD |
7173 | Send the signal named by | |
7174 | .I sigspec | |
ccc6cda3 JA |
7175 | or |
7176 | .I signum | |
726f6388 JA |
7177 | to the processes named by |
7178 | .I pid | |
7179 | or | |
7180 | .IR jobspec . | |
7181 | .I sigspec | |
61deeb13 | 7182 | is either a case-insensitive signal name such as |
726f6388 JA |
7183 | .SM |
7184 | .B SIGKILL | |
61deeb13 | 7185 | (with or without the |
726f6388 JA |
7186 | .SM |
7187 | .B SIG | |
61deeb13 CR |
7188 | prefix) or a signal number; |
7189 | .I signum | |
7190 | is a signal number. | |
726f6388 JA |
7191 | If |
7192 | .I sigspec | |
7193 | is not present, then | |
7194 | .SM | |
7195 | .B SIGTERM | |
cce855bc JA |
7196 | is assumed. |
7197 | An argument of | |
726f6388 | 7198 | .B \-l |
cce855bc JA |
7199 | lists the signal names. |
7200 | If any arguments are supplied when | |
726f6388 | 7201 | .B \-l |
cce855bc JA |
7202 | is given, the names of the signals corresponding to the arguments are |
7203 | listed, and the return status is 0. | |
7204 | The \fIexit_status\fP argument to | |
ccc6cda3 | 7205 | .B \-l |
cce855bc JA |
7206 | is a number specifying either a signal number or the exit status of |
7207 | a process terminated by a signal. | |
726f6388 JA |
7208 | .B kill |
7209 | returns true if at least one signal was successfully sent, or false | |
cce855bc | 7210 | if an error occurs or an invalid option is encountered. |
726f6388 JA |
7211 | .TP |
7212 | \fBlet\fP \fIarg\fP [\fIarg\fP ...] | |
7213 | Each | |
7214 | .I arg | |
7215 | is an arithmetic expression to be evaluated (see | |
7216 | .SM | |
7217 | .BR "ARITHMETIC EVALUATION" ). | |
7218 | If the last | |
7219 | .I arg | |
7220 | evaluates to 0, | |
7221 | .B let | |
7222 | returns 1; 0 is returned otherwise. | |
7223 | .TP | |
bb70624e | 7224 | \fBlocal\fP [\fIoption\fP] [\fIname\fP[=\fIvalue\fP] ...] |
cce855bc JA |
7225 | For each argument, a local variable named |
7226 | .I name | |
7227 | is created, and assigned | |
726f6388 | 7228 | .IR value . |
bb70624e | 7229 | The \fIoption\fP can be any of the options accepted by \fBdeclare\fP. |
726f6388 JA |
7230 | When |
7231 | .B local | |
7232 | is used within a function, it causes the variable | |
7233 | .I name | |
7234 | to have a visible scope restricted to that function and its children. | |
7235 | With no operands, | |
7236 | .B local | |
7237 | writes a list of local variables to the standard output. It is | |
7238 | an error to use | |
7239 | .B local | |
7240 | when not within a function. The return status is 0 unless | |
7241 | .B local | |
bb70624e | 7242 | is used outside a function, an invalid |
726f6388 | 7243 | .I name |
bb70624e JA |
7244 | is supplied, or |
7245 | \fIname\fP is a readonly variable. | |
726f6388 JA |
7246 | .TP |
7247 | .B logout | |
7248 | Exit a login shell. | |
7249 | .TP | |
ccc6cda3 | 7250 | \fBpopd\fP [\-\fBn\fP] [+\fIn\fP] [\-\fIn\fP] |
726f6388 JA |
7251 | Removes entries from the directory stack. With no arguments, |
7252 | removes the top directory from the stack, and performs a | |
7253 | .B cd | |
7254 | to the new top directory. | |
ccc6cda3 | 7255 | Arguments, if supplied, have the following meanings: |
726f6388 JA |
7256 | .RS |
7257 | .PD 0 | |
7258 | .TP | |
ccc6cda3 JA |
7259 | \fB+\fP\fIn\fP |
7260 | Removes the \fIn\fPth entry counting from the left of the list | |
726f6388 JA |
7261 | shown by |
7262 | .BR dirs , | |
bb70624e JA |
7263 | starting with zero. For example: |
7264 | .if n ``popd +0'' | |
7265 | .if t \f(CWpopd +0\fP | |
7266 | removes the first directory, | |
7267 | .if n ``popd +1'' | |
7268 | .if t \f(CWpopd +1\fP | |
7269 | the second. | |
726f6388 | 7270 | .TP |
ccc6cda3 JA |
7271 | \fB\-\fP\fIn\fP |
7272 | Removes the \fIn\fPth entry counting from the right of the list | |
726f6388 JA |
7273 | shown by |
7274 | .BR dirs , | |
bb70624e JA |
7275 | starting with zero. For example: |
7276 | .if n ``popd -0'' | |
7277 | .if t \f(CWpopd -0\fP | |
7278 | removes the last directory, | |
7279 | .if n ``popd -1'' | |
7280 | .if t \f(CWpopd -1\fP | |
7281 | the next to last. | |
ccc6cda3 JA |
7282 | .TP |
7283 | .B \-n | |
7284 | Suppresses the normal change of directory when removing directories | |
7285 | from the stack, so that only the stack is manipulated. | |
726f6388 JA |
7286 | .PD |
7287 | .PP | |
7288 | If the | |
7289 | .B popd | |
7290 | command is successful, a | |
7291 | .B dirs | |
7292 | is performed as well, and the return status is 0. | |
7293 | .B popd | |
cce855bc | 7294 | returns false if an invalid option is encountered, the directory stack |
726f6388 JA |
7295 | is empty, a non-existent directory stack entry is specified, or the |
7296 | directory change fails. | |
7297 | .RE | |
7298 | .TP | |
3ee6b87d | 7299 | \fBprintf\fP [\fB\-v\fP \fIvar\fP] \fIformat\fP [\fIarguments\fP] |
cce855bc JA |
7300 | Write the formatted \fIarguments\fP to the standard output under the |
7301 | control of the \fIformat\fP. | |
7302 | The \fIformat\fP is a character string which contains three types of objects: | |
7303 | plain characters, which are simply copied to standard output, character | |
7304 | escape sequences, which are converted and copied to the standard output, and | |
7305 | format specifications, each of which causes printing of the next successive | |
7306 | \fIargument\fP. | |
f73dda09 | 7307 | In addition to the standard \fIprintf\fP(1) formats, \fB%b\fP causes |
cce855bc | 7308 | \fBprintf\fP to expand backslash escape sequences in the corresponding |
5e13499c CR |
7309 | \fIargument\fP (except that \fB\ec\fP terminates output, backslashes in |
7310 | \fB\e'\fP, \fB\e"\fP, and \fB\e?\fP are not removed, and octal escapes | |
7311 | beginning with \fB\e0\fP may contain up to four digits), | |
7312 | and \fB%q\fP causes \fBprintf\fP to output the corresponding | |
cce855bc JA |
7313 | \fIargument\fP in a format that can be reused as shell input. |
7314 | .sp 1 | |
3ee6b87d CR |
7315 | The \fB\-v\fP option causes the output to be assigned to the variable |
7316 | \fIvar\fP rather than being printed to the standard output. | |
7317 | .sp 1 | |
cce855bc JA |
7318 | The \fIformat\fP is reused as necessary to consume all of the \fIarguments\fP. |
7319 | If the \fIformat\fP requires more \fIarguments\fP than are supplied, the | |
7320 | extra format specifications behave as if a zero value or null string, as | |
bb70624e JA |
7321 | appropriate, had been supplied. The return value is zero on success, |
7322 | non-zero on failure. | |
cce855bc | 7323 | .TP |
ccc6cda3 | 7324 | \fBpushd\fP [\fB\-n\fP] [\fIdir\fP] |
7117c2d2 | 7325 | .PD 0 |
726f6388 | 7326 | .TP |
ccc6cda3 | 7327 | \fBpushd\fP [\fB\-n\fP] [+\fIn\fP] [\-\fIn\fP] |
726f6388 JA |
7328 | .PD |
7329 | Adds a directory to the top of the directory stack, or rotates | |
7330 | the stack, making the new top of the stack the current working | |
7331 | directory. With no arguments, exchanges the top two directories | |
7332 | and returns 0, unless the directory stack is empty. | |
ccc6cda3 | 7333 | Arguments, if supplied, have the following meanings: |
726f6388 JA |
7334 | .RS |
7335 | .PD 0 | |
7336 | .TP | |
ccc6cda3 | 7337 | \fB+\fP\fIn\fP |
726f6388 JA |
7338 | Rotates the stack so that the \fIn\fPth directory |
7339 | (counting from the left of the list shown by | |
d166f048 JA |
7340 | .BR dirs , |
7341 | starting with zero) | |
726f6388 JA |
7342 | is at the top. |
7343 | .TP | |
ccc6cda3 | 7344 | \fB\-\fP\fIn\fP |
726f6388 | 7345 | Rotates the stack so that the \fIn\fPth directory |
d166f048 JA |
7346 | (counting from the right of the list shown by |
7347 | .BR dirs , | |
7348 | starting with zero) is at the top. | |
726f6388 | 7349 | .TP |
ccc6cda3 JA |
7350 | .B \-n |
7351 | Suppresses the normal change of directory when adding directories | |
7352 | to the stack, so that only the stack is manipulated. | |
7353 | .TP | |
bb70624e | 7354 | .I dir |
ccc6cda3 | 7355 | Adds |
726f6388 JA |
7356 | .I dir |
7357 | to the directory stack at the top, making it the | |
7358 | new current working directory. | |
7359 | .PD | |
7360 | .PP | |
7361 | If the | |
7362 | .B pushd | |
7363 | command is successful, a | |
7364 | .B dirs | |
7365 | is performed as well. | |
7366 | If the first form is used, | |
7367 | .B pushd | |
7368 | returns 0 unless the cd to | |
7369 | .I dir | |
7370 | fails. With the second form, | |
7371 | .B pushd | |
7372 | returns 0 unless the directory stack is empty, | |
ccc6cda3 | 7373 | a non-existent directory stack element is specified, |
726f6388 JA |
7374 | or the directory change to the specified new current directory |
7375 | fails. | |
7376 | .RE | |
7377 | .TP | |
ccc6cda3 | 7378 | \fBpwd\fP [\fB\-LP\fP] |
bb70624e JA |
7379 | Print the absolute pathname of the current working directory. |
7380 | The pathname printed contains no symbolic links if the | |
726f6388 | 7381 | .B \-P |
ccc6cda3 JA |
7382 | option is supplied or the |
7383 | .B \-o physical | |
726f6388 JA |
7384 | option to the |
7385 | .B set | |
ccc6cda3 JA |
7386 | builtin command is enabled. |
7387 | If the | |
7388 | .B \-L | |
bb70624e | 7389 | option is used, the pathname printed may contain symbolic links. |
ccc6cda3 | 7390 | The return status is 0 unless an error occurs while |
cce855bc JA |
7391 | reading the name of the current directory or an |
7392 | invalid option is supplied. | |
726f6388 | 7393 | .TP |
7117c2d2 JA |
7394 | \fBread\fP [\fB\-ers\fP] [\fB\-u\fP \fIfd\fP] [\fB\-t\fP \fItimeout\fP] [\fB\-a\fP \fIaname\fP] [\fB\-p\fP \fIprompt\fP] [\fB\-n\fP \fInchars\fP] [\fB\-d\fP \fIdelim\fP] [\fIname\fP ...] |
7395 | One line is read from the standard input, or from the file descriptor | |
7396 | \fIfd\fP supplied as an argument to the \fB\-u\fP option, and the first word | |
726f6388 JA |
7397 | is assigned to the first |
7398 | .IR name , | |
7399 | the second word to the second | |
7400 | .IR name , | |
cce855bc JA |
7401 | and so on, with leftover words and their intervening separators assigned |
7402 | to the last | |
726f6388 | 7403 | .IR name . |
7117c2d2 | 7404 | If there are fewer words read from the input stream than names, |
cce855bc JA |
7405 | the remaining names are assigned empty values. |
7406 | The characters in | |
726f6388 JA |
7407 | .SM |
7408 | .B IFS | |
cce855bc | 7409 | are used to split the line into words. |
b72432fd JA |
7410 | The backslash character (\fB\e\fP) may be used to remove any special |
7411 | meaning for the next character read and for line continuation. | |
cce855bc | 7412 | Options, if supplied, have the following meanings: |
ccc6cda3 JA |
7413 | .RS |
7414 | .PD 0 | |
7415 | .TP | |
bb70624e | 7416 | .B \-a \fIaname\fP |
ccc6cda3 JA |
7417 | The words are assigned to sequential indices |
7418 | of the array variable | |
7419 | .IR aname , | |
7420 | starting at 0. | |
7421 | .I aname | |
7422 | is unset before any new values are assigned. | |
cce855bc | 7423 | Other \fIname\fP arguments are ignored. |
ccc6cda3 | 7424 | .TP |
bb70624e JA |
7425 | .B \-d \fIdelim\fP |
7426 | The first character of \fIdelim\fP is used to terminate the input line, | |
7427 | rather than newline. | |
7428 | .TP | |
ccc6cda3 JA |
7429 | .B \-e |
7430 | If the standard input | |
7431 | is coming from a terminal, | |
7432 | .B readline | |
7433 | (see | |
7434 | .SM | |
7435 | .B READLINE | |
7436 | above) is used to obtain the line. | |
bb70624e JA |
7437 | .TP |
7438 | .B \-n \fInchars\fP | |
7439 | \fBread\fP returns after reading \fInchars\fP characters rather than | |
7440 | waiting for a complete line of input. | |
7441 | .TP | |
7442 | .B \-p \fIprompt\fP | |
f73dda09 | 7443 | Display \fIprompt\fP on standard error, without a |
bb70624e JA |
7444 | trailing newline, before attempting to read any input. The prompt |
7445 | is displayed only if input is coming from a terminal. | |
7446 | .TP | |
7447 | .B \-r | |
7448 | Backslash does not act as an escape character. | |
7449 | The backslash is considered to be part of the line. | |
7450 | In particular, a backslash-newline pair may not be used as a line | |
7451 | continuation. | |
7452 | .TP | |
7453 | .B \-s | |
7454 | Silent mode. If input is coming from a terminal, characters are | |
7455 | not echoed. | |
7456 | .TP | |
7457 | .B \-t \fItimeout\fP | |
7458 | Cause \fBread\fP to time out and return failure if a complete line of | |
7459 | input is not read within \fItimeout\fP seconds. | |
7460 | This option has no effect if \fBread\fP is not reading input from the | |
7461 | terminal or a pipe. | |
7117c2d2 | 7462 | .TP |
0f445e6c | 7463 | .B \-u \fIfd\fP |
7117c2d2 | 7464 | Read input from file descriptor \fIfd\fP. |
ccc6cda3 JA |
7465 | .PD |
7466 | .PP | |
7467 | If no | |
726f6388 JA |
7468 | .I names |
7469 | are supplied, the line read is assigned to the variable | |
7470 | .SM | |
7471 | .BR REPLY . | |
7117c2d2 JA |
7472 | The return code is zero, unless end-of-file is encountered, \fBread\fP |
7473 | times out, or an invalid file descriptor is supplied as the argument to | |
7474 | \fB\-u\fP. | |
ccc6cda3 | 7475 | .RE |
726f6388 | 7476 | .TP |
d3a24ed2 | 7477 | \fBreadonly\fP [\fB\-apf\fP] [\fIname\fP[=\fIword\fP] ...] |
726f6388 JA |
7478 | .PD |
7479 | The given | |
ccc6cda3 JA |
7480 | \fInames\fP are marked readonly; the values of these |
7481 | .I names | |
726f6388 JA |
7482 | may not be changed by subsequent assignment. |
7483 | If the | |
7484 | .B \-f | |
7485 | option is supplied, the functions corresponding to the | |
7486 | \fInames\fP are so | |
ccc6cda3 JA |
7487 | marked. |
7488 | The | |
7489 | .B \-a | |
7490 | option restricts the variables to arrays. | |
7491 | If no | |
7492 | .I name | |
7493 | arguments are given, or if the | |
726f6388 | 7494 | .B \-p |
ccc6cda3 | 7495 | option is supplied, a list of all readonly names is printed. |
cce855bc JA |
7496 | The |
7497 | .B \-p | |
bb70624e JA |
7498 | option causes output to be displayed in a format that |
7499 | may be reused as input. | |
d3a24ed2 CR |
7500 | If a variable name is followed by =\fIword\fP, the value of |
7501 | the variable is set to \fIword\fP. | |
cce855bc | 7502 | The return status is 0 unless an invalid option is encountered, |
ccc6cda3 JA |
7503 | one of the |
7504 | .I names | |
cce855bc | 7505 | is not a valid shell variable name, or |
726f6388 JA |
7506 | .B \-f |
7507 | is supplied with a | |
7508 | .I name | |
7509 | that is not a function. | |
7510 | .TP | |
7511 | \fBreturn\fP [\fIn\fP] | |
7512 | Causes a function to exit with the return value specified by | |
7513 | .IR n . | |
7514 | If | |
7515 | .I n | |
7516 | is omitted, the return status is that of the last command | |
7517 | executed in the function body. If used outside a function, | |
7518 | but during execution of a script by the | |
7519 | .B . | |
7520 | (\fBsource\fP) command, it causes the shell to stop executing | |
7521 | that script and return either | |
7522 | .I n | |
7523 | or the exit status of the last command executed within the | |
7524 | script as the exit status of the script. If used outside a | |
7525 | function and not during execution of a script by \fB.\fP\^, | |
7526 | the return status is false. | |
d3a24ed2 CR |
7527 | Any command associated with the \fBRETURN\fP trap is executed |
7528 | before execution resumes after the function or script. | |
726f6388 | 7529 | .TP |
ccc6cda3 JA |
7530 | \fBset\fP [\fB\-\-abefhkmnptuvxBCHP\fP] [\fB\-o\fP \fIoption\fP] [\fIarg\fP ...] |
7531 | Without options, the name and value of each shell variable are displayed | |
54cdd75a CR |
7532 | in a format that can be reused as input |
7533 | for setting or resetting the currently-set variables. | |
7534 | Read-only variables cannot be reset. | |
7535 | In \fIposix mode\fP, only shell variables are listed. | |
cce855bc | 7536 | The output is sorted according to the current locale. |
ccc6cda3 JA |
7537 | When options are specified, they set or unset shell attributes. |
7538 | Any arguments remaining after the options are processed are treated | |
7539 | as values for the positional parameters and are assigned, in order, to | |
7540 | .BR $1 , | |
7541 | .BR $2 , | |
7542 | .B ... | |
7543 | .BR $\fIn\fP . | |
7544 | Options, if specified, have the following meanings: | |
726f6388 JA |
7545 | .RS |
7546 | .PD 0 | |
7547 | .TP 8 | |
7548 | .B \-a | |
5e13499c CR |
7549 | Automatically mark variables and functions which are modified or |
7550 | created for export to the environment of subsequent commands. | |
726f6388 JA |
7551 | .TP 8 |
7552 | .B \-b | |
ccc6cda3 JA |
7553 | Report the status of terminated background jobs |
7554 | immediately, rather than before the next primary prompt. This is | |
7555 | effective only when job control is enabled. | |
726f6388 JA |
7556 | .TP 8 |
7557 | .B \-e | |
ccc6cda3 | 7558 | Exit immediately if a \fIsimple command\fP (see |
726f6388 JA |
7559 | .SM |
7560 | .B SHELL GRAMMAR | |
d3a24ed2 CR |
7561 | above) exits with a non-zero status. |
7562 | The shell does not exit if the | |
7563 | command that fails is part of the command list immediately following a | |
7564 | .B while | |
726f6388 | 7565 | or |
d3a24ed2 CR |
7566 | .B until |
7567 | keyword, | |
7568 | part of the test in an | |
726f6388 JA |
7569 | .I if |
7570 | statement, part of a | |
7571 | .B && | |
7572 | or | |
ccc6cda3 | 7573 | .B \(bv\(bv |
726f6388 JA |
7574 | list, or if the command's return value is |
7575 | being inverted via | |
7576 | .BR ! . | |
f73dda09 | 7577 | A trap on \fBERR\fP, if set, is executed before the shell exits. |
726f6388 JA |
7578 | .TP 8 |
7579 | .B \-f | |
7580 | Disable pathname expansion. | |
7581 | .TP 8 | |
7582 | .B \-h | |
ccc6cda3 | 7583 | Remember the location of commands as they are looked up for execution. |
cce855bc | 7584 | This is enabled by default. |
726f6388 JA |
7585 | .TP 8 |
7586 | .B \-k | |
ccc6cda3 JA |
7587 | All arguments in the form of assignment statements |
7588 | are placed in the environment for a command, not just | |
7589 | those that precede the command name. | |
726f6388 JA |
7590 | .TP 8 |
7591 | .B \-m | |
cce855bc | 7592 | Monitor mode. Job control is enabled. This option is on |
726f6388 JA |
7593 | by default for interactive shells on systems that support |
7594 | it (see | |
7595 | .SM | |
7596 | .B JOB CONTROL | |
7597 | above). Background processes run in a separate process | |
7598 | group and a line containing their exit status is printed | |
7599 | upon their completion. | |
7600 | .TP 8 | |
7601 | .B \-n | |
7602 | Read commands but do not execute them. This may be used to | |
ccc6cda3 | 7603 | check a shell script for syntax errors. This is ignored by |
726f6388 JA |
7604 | interactive shells. |
7605 | .TP 8 | |
ccc6cda3 JA |
7606 | .B \-o \fIoption\-name\fP |
7607 | The \fIoption\-name\fP can be one of the following: | |
726f6388 JA |
7608 | .RS |
7609 | .TP 8 | |
7610 | .B allexport | |
7611 | Same as | |
7612 | .BR \-a . | |
7613 | .TP 8 | |
7614 | .B braceexpand | |
ccc6cda3 JA |
7615 | Same as |
7616 | .BR \-B . | |
726f6388 JA |
7617 | .TP 8 |
7618 | .B emacs | |
7619 | Use an emacs-style command line editing interface. This is enabled | |
7620 | by default when the shell is interactive, unless the shell is started | |
7621 | with the | |
ccc6cda3 | 7622 | .B \-\-noediting |
726f6388 JA |
7623 | option. |
7624 | .TP 8 | |
d3a24ed2 CR |
7625 | .B errtrace |
7626 | Same as | |
7627 | .BR \-E . | |
7628 | .TP 8 | |
7629 | .B functrace | |
7630 | Same as | |
7631 | .BR \-T . | |
7632 | .TP 8 | |
726f6388 JA |
7633 | .B errexit |
7634 | Same as | |
7635 | .BR \-e . | |
7636 | .TP 8 | |
ccc6cda3 JA |
7637 | .B hashall |
7638 | Same as | |
7639 | .BR \-h . | |
7640 | .TP 8 | |
726f6388 JA |
7641 | .B histexpand |
7642 | Same as | |
7643 | .BR \-H . | |
7644 | .TP 8 | |
ccc6cda3 JA |
7645 | .B history |
7646 | Enable command history, as described above under | |
7647 | .SM | |
7648 | .BR HISTORY . | |
7649 | This option is on by default in interactive shells. | |
7650 | .TP 8 | |
726f6388 | 7651 | .B ignoreeof |
28ef6c31 JA |
7652 | The effect is as if the shell command |
7653 | .if t \f(CWIGNOREEOF=10\fP | |
7654 | .if n ``IGNOREEOF=10'' | |
7655 | had been executed | |
726f6388 JA |
7656 | (see |
7657 | .B Shell Variables | |
7658 | above). | |
7659 | .TP 8 | |
ccc6cda3 JA |
7660 | .B keyword |
7661 | Same as | |
7662 | .BR \-k . | |
726f6388 JA |
7663 | .TP 8 |
7664 | .B monitor | |
7665 | Same as | |
7666 | .BR \-m . | |
7667 | .TP 8 | |
7668 | .B noclobber | |
7669 | Same as | |
7670 | .BR \-C . | |
7671 | .TP 8 | |
7672 | .B noexec | |
7673 | Same as | |
7674 | .BR \-n . | |
7675 | .TP 8 | |
7676 | .B noglob | |
7677 | Same as | |
7678 | .BR \-f . | |
f73dda09 JA |
7679 | .B nolog |
7680 | Currently ignored. | |
726f6388 | 7681 | .TP 8 |
726f6388 JA |
7682 | .B notify |
7683 | Same as | |
7684 | .BR \-b . | |
7685 | .TP 8 | |
7686 | .B nounset | |
7687 | Same as | |
7688 | .BR \-u . | |
7689 | .TP 8 | |
ccc6cda3 JA |
7690 | .B onecmd |
7691 | Same as | |
7692 | .BR \-t . | |
7693 | .TP 8 | |
726f6388 JA |
7694 | .B physical |
7695 | Same as | |
7696 | .BR \-P . | |
7697 | .TP 8 | |
d3a24ed2 CR |
7698 | .B pipefail |
7699 | If set, the return value of a pipeline is the value of the last | |
7700 | (rightmost) command to exit with a non-zero status, or zero if all | |
7701 | commands in the pipeline exit successfully. | |
7702 | This option is disabled by default. | |
7703 | .TP 8 | |
726f6388 | 7704 | .B posix |
ccc6cda3 JA |
7705 | Change the behavior of |
7706 | .B bash | |
7707 | where the default operation differs | |
54cdd75a | 7708 | from the POSIX 1003.2 standard to match the standard (\fIposix mode\fP). |
726f6388 JA |
7709 | .TP 8 |
7710 | .B privileged | |
7711 | Same as | |
7712 | .BR \-p . | |
7713 | .TP 8 | |
7714 | .B verbose | |
7715 | Same as | |
7716 | .BR \-v . | |
7717 | .TP 8 | |
7718 | .B vi | |
7719 | Use a vi-style command line editing interface. | |
7720 | .TP 8 | |
7721 | .B xtrace | |
7722 | Same as | |
7723 | .BR \-x . | |
ccc6cda3 | 7724 | .sp .5 |
726f6388 | 7725 | .PP |
ccc6cda3 JA |
7726 | If |
7727 | .B \-o | |
7728 | is supplied with no \fIoption\-name\fP, the values of the current options are | |
726f6388 | 7729 | printed. |
ccc6cda3 JA |
7730 | If |
7731 | .B +o | |
7732 | is supplied with no \fIoption\-name\fP, a series of | |
7733 | .B set | |
7734 | commands to recreate the current option settings is displayed on | |
7735 | the standard output. | |
726f6388 JA |
7736 | .RE |
7737 | .TP 8 | |
7738 | .B \-p | |
7739 | Turn on | |
7740 | .I privileged | |
7741 | mode. In this mode, the | |
bb70624e | 7742 | .SM |
726f6388 | 7743 | .B $ENV |
b72432fd | 7744 | and |
bb70624e | 7745 | .SM |
b72432fd JA |
7746 | .B $BASH_ENV |
7747 | files are not processed, shell functions are not inherited from the | |
bb70624e JA |
7748 | environment, and the |
7749 | .SM | |
7750 | .B SHELLOPTS | |
7751 | variable, if it appears in the environment, is ignored. | |
b72432fd JA |
7752 | If the shell is started with the effective user (group) id not equal to the |
7753 | real user (group) id, and the \fB\-p\fP option is not supplied, these actions | |
7754 | are taken and the effective user id is set to the real user id. | |
7755 | If the \fB\-p\fP option is supplied at startup, the effective user id is | |
7756 | not reset. | |
cce855bc | 7757 | Turning this option off causes the effective user |
726f6388 JA |
7758 | and group ids to be set to the real user and group ids. |
7759 | .TP 8 | |
7760 | .B \-t | |
7761 | Exit after reading and executing one command. | |
7762 | .TP 8 | |
7763 | .B \-u | |
7764 | Treat unset variables as an error when performing | |
7765 | parameter expansion. If expansion is attempted on an | |
7766 | unset variable, the shell prints an error message, and, | |
ccc6cda3 | 7767 | if not interactive, exits with a non-zero status. |
726f6388 JA |
7768 | .TP 8 |
7769 | .B \-v | |
7770 | Print shell input lines as they are read. | |
7771 | .TP 8 | |
7772 | .B \-x | |
ccc6cda3 | 7773 | After expanding each \fIsimple command\fP, |
d3a24ed2 CR |
7774 | \fBfor\fP command, \fBcase\fP command, \fBselect\fP command, or |
7775 | arithmetic \fBfor\fP command, display the expanded value of | |
726f6388 JA |
7776 | .SM |
7777 | .BR PS4 , | |
d3a24ed2 CR |
7778 | followed by the command and its expanded arguments |
7779 | or associated word list. | |
726f6388 | 7780 | .TP 8 |
ccc6cda3 JA |
7781 | .B \-B |
7782 | The shell performs brace expansion (see | |
7783 | .B Brace Expansion | |
7784 | above). This is on by default. | |
726f6388 JA |
7785 | .TP 8 |
7786 | .B \-C | |
ccc6cda3 JA |
7787 | If set, |
7788 | .B bash | |
7789 | does not overwrite an existing file with the | |
7790 | .BR > , | |
7791 | .BR >& , | |
7792 | and | |
7793 | .B <> | |
7794 | redirection operators. This may be overridden when | |
7795 | creating output files by using the redirection operator | |
7796 | .B >| | |
7797 | instead of | |
7798 | .BR > . | |
726f6388 | 7799 | .TP 8 |
d3a24ed2 CR |
7800 | .B \-E |
7801 | If set, any trap on \fBERR\fP is inherited by shell functions, command | |
7802 | substitutions, and commands executed in a subshell environment. | |
7803 | The \fBERR\fP trap is normally not inherited in such cases. | |
7804 | .TP 8 | |
726f6388 JA |
7805 | .B \-H |
7806 | Enable | |
7807 | .B ! | |
cce855bc | 7808 | style history substitution. This option is on by |
726f6388 JA |
7809 | default when the shell is interactive. |
7810 | .TP 8 | |
7811 | .B \-P | |
ccc6cda3 JA |
7812 | If set, the shell does not follow symbolic links when executing |
7813 | commands such as | |
726f6388 | 7814 | .B cd |
ccc6cda3 JA |
7815 | that change the current working directory. It uses the |
7816 | physical directory structure instead. By default, | |
7817 | .B bash | |
7818 | follows the logical chain of directories when performing commands | |
7819 | which change the current directory. | |
726f6388 | 7820 | .TP 8 |
d3a24ed2 | 7821 | .B \-T |
76a8d78d CR |
7822 | If set, any traps on \fBDEBUG\fP and \fBRETURN\fP are inherited by shell |
7823 | functions, command substitutions, and commands executed in a | |
7824 | subshell environment. | |
7825 | The \fBDEBUG\fP and \fBRETURN\fP traps are normally not inherited | |
7826 | in such cases. | |
d3a24ed2 | 7827 | .TP 8 |
726f6388 | 7828 | .B \-\- |
cce855bc | 7829 | If no arguments follow this option, then the positional parameters are |
726f6388 JA |
7830 | unset. Otherwise, the positional parameters are set to the |
7831 | \fIarg\fPs, even if some of them begin with a | |
7832 | .BR \- . | |
7833 | .TP 8 | |
7834 | .B \- | |
7835 | Signal the end of options, cause all remaining \fIarg\fPs to be | |
7836 | assigned to the positional parameters. The | |
7837 | .B \-x | |
7838 | and | |
7839 | .B \-v | |
7840 | options are turned off. | |
7841 | If there are no \fIarg\fPs, | |
7842 | the positional parameters remain unchanged. | |
7843 | .PD | |
7844 | .PP | |
cce855bc JA |
7845 | The options are off by default unless otherwise noted. |
7846 | Using + rather than \- causes these options to be turned off. | |
7847 | The options can also be specified as arguments to an invocation of | |
7848 | the shell. | |
7849 | The current set of options may be found in | |
726f6388 | 7850 | .BR $\- . |
cce855bc | 7851 | The return status is always true unless an invalid option is encountered. |
726f6388 JA |
7852 | .RE |
7853 | .TP | |
7854 | \fBshift\fP [\fIn\fP] | |
7855 | The positional parameters from \fIn\fP+1 ... are renamed to | |
7856 | .B $1 | |
7857 | .B .... | |
7858 | Parameters represented by the numbers \fB$#\fP | |
7859 | down to \fB$#\fP\-\fIn\fP+1 are unset. | |
ccc6cda3 JA |
7860 | .I n |
7861 | must be a non-negative number less than or equal to \fB$#\fP. | |
726f6388 JA |
7862 | If |
7863 | .I n | |
7864 | is 0, no parameters are changed. | |
7865 | If | |
7866 | .I n | |
7867 | is not given, it is assumed to be 1. | |
726f6388 JA |
7868 | If |
7869 | .I n | |
7870 | is greater than \fB$#\fP, the positional parameters are not changed. | |
ccc6cda3 | 7871 | The return status is greater than zero if |
726f6388 JA |
7872 | .I n |
7873 | is greater than | |
7874 | .B $# | |
ccc6cda3 JA |
7875 | or less than zero; otherwise 0. |
7876 | .TP | |
7877 | \fBshopt\fP [\fB\-pqsu\fP] [\fB\-o\fP] [\fIoptname\fP ...] | |
7878 | Toggle the values of variables controlling optional shell behavior. | |
7879 | With no options, or with the | |
7880 | .B \-p | |
7881 | option, a list of all settable options is displayed, with | |
cce855bc JA |
7882 | an indication of whether or not each is set. |
7883 | The \fB\-p\fP option causes output to be displayed in a form that | |
7884 | may be reused as input. | |
7885 | Other options have the following meanings: | |
ccc6cda3 JA |
7886 | .RS |
7887 | .PD 0 | |
7888 | .TP | |
7889 | .B \-s | |
7890 | Enable (set) each \fIoptname\fP. | |
7891 | .TP | |
7892 | .B \-u | |
7893 | Disable (unset) each \fIoptname\fP. | |
7894 | .TP | |
7895 | .B \-q | |
7896 | Suppresses normal output (quiet mode); the return status indicates | |
7897 | whether the \fIoptname\fP is set or unset. | |
7898 | If multiple \fIoptname\fP arguments are given with | |
7899 | .BR \-q , | |
7900 | the return status is zero if all \fIoptnames\fP are enabled; non-zero | |
7901 | otherwise. | |
7902 | .TP | |
7903 | .B \-o | |
7904 | Restricts the values of \fIoptname\fP to be those defined for the | |
7905 | .B \-o | |
7906 | option to the | |
7907 | .B set | |
7908 | builtin. | |
7909 | .PD | |
7910 | .PP | |
7911 | If either | |
7912 | .B \-s | |
7913 | or | |
7914 | .B \-u | |
7915 | is used with no \fIoptname\fP arguments, the display is limited to | |
7916 | those options which are set or unset, respectively. | |
7917 | Unless otherwise noted, the \fBshopt\fP options are disabled (unset) | |
7918 | by default. | |
7919 | .PP | |
7920 | The return status when listing options is zero if all \fIoptnames\fP | |
7921 | are enabled, non-zero otherwise. When setting or unsetting options, | |
cce855bc | 7922 | the return status is zero unless an \fIoptname\fP is not a valid shell |
ccc6cda3 JA |
7923 | option. |
7924 | .PP | |
7925 | The list of \fBshopt\fP options is: | |
7926 | .if t .sp .5v | |
7927 | .if n .sp 1v | |
7928 | .PD 0 | |
7929 | .TP 8 | |
7930 | .B cdable_vars | |
7931 | If set, an argument to the | |
7932 | .B cd | |
7933 | builtin command that | |
7934 | is not a directory is assumed to be the name of a variable whose | |
7935 | value is the directory to change to. | |
7936 | .TP 8 | |
7937 | .B cdspell | |
7938 | If set, minor errors in the spelling of a directory component in a | |
7939 | .B cd | |
7940 | command will be corrected. | |
7941 | The errors checked for are transposed characters, | |
7942 | a missing character, and one character too many. | |
7943 | If a correction is found, the corrected file name is printed, | |
7944 | and the command proceeds. | |
d166f048 | 7945 | This option is only used by interactive shells. |
ccc6cda3 JA |
7946 | .TP 8 |
7947 | .B checkhash | |
7948 | If set, \fBbash\fP checks that a command found in the hash | |
7949 | table exists before trying to execute it. If a hashed command no | |
7950 | longer exists, a normal path search is performed. | |
7951 | .TP 8 | |
7952 | .B checkwinsize | |
7953 | If set, \fBbash\fP checks the window size after each command | |
7954 | and, if necessary, updates the values of | |
7955 | .SM | |
7956 | .B LINES | |
7957 | and | |
7958 | .SM | |
7959 | .BR COLUMNS . | |
7960 | .TP 8 | |
7961 | .B cmdhist | |
7962 | If set, | |
7963 | .B bash | |
7964 | attempts to save all lines of a multiple-line | |
7965 | command in the same history entry. This allows | |
7966 | easy re-editing of multi-line commands. | |
7967 | .TP 8 | |
7968 | .B dotglob | |
7969 | If set, | |
7970 | .B bash | |
7971 | includes filenames beginning with a `.' in the results of pathname | |
7972 | expansion. | |
7973 | .TP 8 | |
7974 | .B execfail | |
7975 | If set, a non-interactive shell will not exit if | |
7976 | it cannot execute the file specified as an argument to the | |
7977 | .B exec | |
7978 | builtin command. An interactive shell does not exit if | |
7979 | .B exec | |
7980 | fails. | |
7981 | .TP 8 | |
7982 | .B expand_aliases | |
7983 | If set, aliases are expanded as described above under | |
7984 | .SM | |
7985 | .BR ALIASES . | |
7986 | This option is enabled by default for interactive shells. | |
7987 | .TP 8 | |
d3a24ed2 CR |
7988 | .B extdebug |
7989 | If set, behavior intended for use by debuggers is enabled: | |
7990 | .RS | |
7991 | .TP | |
7992 | .B 1. | |
7993 | The \fB\-F\fP option to the \fBdeclare\fP builtin displays the source | |
7994 | file name and line number corresponding to each function name supplied | |
7995 | as an argument. | |
7996 | .TP | |
7997 | .B 2. | |
7998 | If the command run by the \fBDEBUG\fP trap returns a non-zero value, the | |
7999 | next command is skipped and not executed. | |
8000 | .TP | |
8001 | .B 3. | |
8002 | If the command run by the \fBDEBUG\fP trap returns a value of 2, and the | |
8003 | shell is executing in a subroutine (a shell function or a shell script | |
8004 | executed by the \fB.\fP or \fBsource\fP builtins), a call to | |
8005 | \fBreturn\fP is simulated. | |
2206f89a CR |
8006 | .TP |
8007 | .B 4. | |
8008 | \fBBASH_ARGC\fP and \fBBASH_ARGV\fP are updated as described in their | |
8009 | descriptions above. | |
8010 | .TP | |
8011 | .B 5. | |
8012 | Function tracing is enabled: command substitution, shell functions, and | |
8013 | subshells invoked with \fB(\fP \fIcommand\fP \fB)\fP inherit the | |
8014 | \fBDEBUG\fP and \fBRETURN\fP traps. | |
8015 | .TP | |
8016 | .B 6. | |
8017 | Error tracing is enabled: command substitution, shell functions, and | |
8018 | subshells invoked with \fB(\fP \fIcommand\fP \fB)\fP inherit the | |
8019 | \fBERROR\fP trap. | |
d3a24ed2 CR |
8020 | .RE |
8021 | .TP 8 | |
cce855bc JA |
8022 | .B extglob |
8023 | If set, the extended pattern matching features described above under | |
8024 | \fBPathname Expansion\fP are enabled. | |
8025 | .TP 8 | |
d3a24ed2 CR |
8026 | .B extquote |
8027 | If set, \fB$\fP'\fIstring\fP' and \fB$\fP"\fIstring\fP" quoting is | |
8028 | performed within \fB${\fP\fIparameter\fP\fB}\fP expansions | |
8029 | enclosed in double quotes. This option is enabled by default. | |
8030 | .TP 8 | |
8031 | .B failglob | |
8032 | If set, patterns which fail to match filenames during pathname expansion | |
8033 | result in an expansion error. | |
8034 | .TP 8 | |
8035 | .B force_fignore | |
8036 | If set, the suffixes specified by the \fBFIGNORE\fP shell variable | |
8037 | cause words to be ignored when performing word completion even if | |
8038 | the ignored words are the only possible completions. | |
8039 | See | |
8040 | .SM | |
8041 | \fBSHELL VARIABLES\fP | |
8042 | above for a description of \fBFIGNORE\fP. | |
8043 | This option is enabled by default. | |
8044 | .TP 8 | |
8045 | .B gnu_errfmt | |
8046 | If set, shell error messages are written in the standard GNU error | |
8047 | message format. | |
8048 | .TP 8 | |
ccc6cda3 JA |
8049 | .B histappend |
8050 | If set, the history list is appended to the file named by the value | |
8051 | of the | |
8052 | .B HISTFILE | |
8053 | variable when the shell exits, rather than overwriting the file. | |
8054 | .TP 8 | |
8055 | .B histreedit | |
8056 | If set, and | |
8057 | .B readline | |
8058 | is being used, a user is given the opportunity to re-edit a | |
8059 | failed history substitution. | |
8060 | .TP 8 | |
8061 | .B histverify | |
8062 | If set, and | |
8063 | .B readline | |
8064 | is being used, the results of history substitution are not immediately | |
8065 | passed to the shell parser. Instead, the resulting line is loaded into | |
8066 | the \fBreadline\fP editing buffer, allowing further modification. | |
8067 | .TP 8 | |
8068 | .B hostcomplete | |
8069 | If set, and | |
8070 | .B readline | |
cce855bc JA |
8071 | is being used, \fBbash\fP will attempt to perform hostname completion when a |
8072 | word containing a \fB@\fP is being completed (see | |
ccc6cda3 JA |
8073 | .B Completing |
8074 | under | |
8075 | .SM | |
8076 | .B READLINE | |
8077 | above). | |
8078 | This is enabled by default. | |
8079 | .TP 8 | |
cce855bc JA |
8080 | .B huponexit |
8081 | If set, \fBbash\fP will send | |
8082 | .SM | |
8083 | .B SIGHUP | |
8084 | to all jobs when an interactive login shell exits. | |
8085 | .TP 8 | |
ccc6cda3 JA |
8086 | .B interactive_comments |
8087 | If set, allow a word beginning with | |
8088 | .B # | |
8089 | to cause that word and all remaining characters on that | |
8090 | line to be ignored in an interactive shell (see | |
8091 | .SM | |
8092 | .B COMMENTS | |
8093 | above). This option is enabled by default. | |
8094 | .TP 8 | |
8095 | .B lithist | |
8096 | If set, and the | |
8097 | .B cmdhist | |
8098 | option is enabled, multi-line commands are saved to the history with | |
8099 | embedded newlines rather than using semicolon separators where possible. | |
8100 | .TP 8 | |
f73dda09 JA |
8101 | .B login_shell |
8102 | The shell sets this option if it is started as a login shell (see | |
8103 | .SM | |
8104 | .B "INVOCATION" | |
8105 | above). | |
8106 | The value may not be changed. | |
8107 | .TP 8 | |
ccc6cda3 JA |
8108 | .B mailwarn |
8109 | If set, and a file that \fBbash\fP is checking for mail has been | |
8110 | accessed since the last time it was checked, the message ``The mail in | |
8111 | \fImailfile\fP has been read'' is displayed. | |
8112 | .TP 8 | |
bb70624e JA |
8113 | .B no_empty_cmd_completion |
8114 | If set, and | |
8115 | .B readline | |
8116 | is being used, | |
8117 | .B bash | |
8118 | will not attempt to search the \fBPATH\fP for possible completions when | |
8119 | completion is attempted on an empty line. | |
8120 | .TP 8 | |
cce855bc JA |
8121 | .B nocaseglob |
8122 | If set, | |
8123 | .B bash | |
8124 | matches filenames in a case\-insensitive fashion when performing pathname | |
8125 | expansion (see | |
8126 | .B Pathname Expansion | |
8127 | above). | |
8128 | .TP 8 | |
2206f89a CR |
8129 | .B nocasematch |
8130 | If set, | |
8131 | .B bash | |
8132 | matches patterns in a case\-insensitive fashion when performing matching | |
8133 | while executing \fBcase\fP or \fB[[\fP conditional commands. | |
8134 | .TP 8 | |
ccc6cda3 JA |
8135 | .B nullglob |
8136 | If set, | |
8137 | .B bash | |
8138 | allows patterns which match no | |
8139 | files (see | |
8140 | .B Pathname Expansion | |
8141 | above) | |
8142 | to expand to a null string, rather than themselves. | |
8143 | .TP 8 | |
bb70624e JA |
8144 | .B progcomp |
8145 | If set, the programmable completion facilities (see | |
8146 | \fBProgrammable Completion\fP above) are enabled. | |
8147 | This option is enabled by default. | |
8148 | .TP 8 | |
ccc6cda3 | 8149 | .B promptvars |
d3a24ed2 CR |
8150 | If set, prompt strings undergo |
8151 | parameter expansion, command substitution, arithmetic | |
8152 | expansion, and quote removal after being expanded as described in | |
ccc6cda3 JA |
8153 | .SM |
8154 | .B PROMPTING | |
8155 | above. This option is enabled by default. | |
8156 | .TP 8 | |
b72432fd JA |
8157 | .B restricted_shell |
8158 | The shell sets this option if it is started in restricted mode (see | |
8159 | .SM | |
8160 | .B "RESTRICTED SHELL" | |
8161 | below). | |
8162 | The value may not be changed. | |
8163 | This is not reset when the startup files are executed, allowing | |
8164 | the startup files to discover whether or not a shell is restricted. | |
8165 | .TP 8 | |
ccc6cda3 JA |
8166 | .B shift_verbose |
8167 | If set, the | |
8168 | .B shift | |
8169 | builtin prints an error message when the shift count exceeds the | |
8170 | number of positional parameters. | |
8171 | .TP 8 | |
8172 | .B sourcepath | |
8173 | If set, the | |
8174 | \fBsource\fP (\fB.\fP) builtin uses the value of | |
8175 | .SM | |
8176 | .B PATH | |
8177 | to find the directory containing the file supplied as an argument. | |
cce855bc | 8178 | This option is enabled by default. |
bb70624e JA |
8179 | .TP 8 |
8180 | .B xpg_echo | |
8181 | If set, the \fBecho\fP builtin expands backslash-escape sequences | |
8182 | by default. | |
ccc6cda3 | 8183 | .RE |
726f6388 JA |
8184 | .TP |
8185 | \fBsuspend\fP [\fB\-f\fP] | |
8186 | Suspend the execution of this shell until it receives a | |
8187 | .SM | |
8188 | .B SIGCONT | |
8189 | signal. The | |
8190 | .B \-f | |
8191 | option says not to complain if this is | |
8192 | a login shell; just suspend anyway. The return status is 0 unless | |
8193 | the shell is a login shell and | |
8194 | .B \-f | |
8195 | is not supplied, or if job control is not enabled. | |
8196 | .TP | |
726f6388 | 8197 | \fBtest\fP \fIexpr\fP |
7117c2d2 | 8198 | .PD 0 |
726f6388 JA |
8199 | .TP |
8200 | \fB[\fP \fIexpr\fP \fB]\fP | |
ccc6cda3 | 8201 | Return a status of 0 or 1 depending on |
726f6388 JA |
8202 | the evaluation of the conditional expression |
8203 | .IR expr . | |
cce855bc JA |
8204 | Each operator and operand must be a separate argument. |
8205 | Expressions are composed of the primaries described above under | |
8206 | .SM | |
8207 | .BR "CONDITIONAL EXPRESSIONS" . | |
3ffb039a CR |
8208 | \fBtest\fP does not accept any options, nor does it accept and ignore |
8209 | an argument of \fB\-\-\fP as signifying the end of options. | |
cce855bc JA |
8210 | .if t .sp 0.5 |
8211 | .if n .sp 1 | |
8212 | Expressions may be combined using the following operators, listed | |
8213 | in decreasing order of precedence. | |
726f6388 JA |
8214 | .RS |
8215 | .PD 0 | |
8216 | .TP | |
726f6388 JA |
8217 | .B ! \fIexpr\fP |
8218 | True if | |
8219 | .I expr | |
8220 | is false. | |
8221 | .TP | |
cce855bc JA |
8222 | .B ( \fIexpr\fP ) |
8223 | Returns the value of \fIexpr\fP. | |
8224 | This may be used to override the normal precedence of operators. | |
8225 | .TP | |
726f6388 JA |
8226 | \fIexpr1\fP \-\fBa\fP \fIexpr2\fP |
8227 | True if both | |
8228 | .I expr1 | |
cce855bc | 8229 | and |
726f6388 JA |
8230 | .I expr2 |
8231 | are true. | |
8232 | .TP | |
8233 | \fIexpr1\fP \-\fBo\fP \fIexpr2\fP | |
8234 | True if either | |
8235 | .I expr1 | |
cce855bc | 8236 | or |
726f6388 JA |
8237 | .I expr2 |
8238 | is true. | |
cce855bc JA |
8239 | .PD |
8240 | .PP | |
8241 | \fBtest\fP and \fB[\fP evaluate conditional | |
8242 | expressions using a set of rules based on the number of arguments. | |
8243 | .if t .sp 0.5 | |
8244 | .if n .sp 1 | |
8245 | .PD 0 | |
726f6388 | 8246 | .TP |
cce855bc JA |
8247 | 0 arguments |
8248 | The expression is false. | |
8249 | .TP | |
8250 | 1 argument | |
8251 | The expression is true if and only if the argument is not null. | |
8252 | .TP | |
8253 | 2 arguments | |
8254 | If the first argument is \fB!\fP, the expression is true if and | |
8255 | only if the second argument is null. | |
8256 | If the first argument is one of the unary conditional operators listed above | |
8257 | under | |
726f6388 | 8258 | .SM |
cce855bc JA |
8259 | .BR "CONDITIONAL EXPRESSIONS" , |
8260 | the expression is true if the unary test is true. | |
8261 | If the first argument is not a valid unary conditional operator, the expression | |
8262 | is false. | |
8263 | .TP | |
8264 | 3 arguments | |
8265 | If the second argument is one of the binary conditional operators listed above | |
8266 | under | |
8267 | .SM | |
8268 | .BR "CONDITIONAL EXPRESSIONS" , | |
8269 | the result of the expression is the result of the binary test using | |
8270 | the first and third arguments as operands. | |
8271 | If the first argument is \fB!\fP, the value is the negation of | |
8272 | the two-argument test using the second and third arguments. | |
8273 | If the first argument is exactly \fB(\fP and the third argument is | |
8274 | exactly \fB)\fP, the result is the one-argument test of the second | |
8275 | argument. | |
8276 | Otherwise, the expression is false. | |
8277 | The \fB\-a\fP and \fB\-o\fP operators are considered binary operators | |
8278 | in this case. | |
8279 | .TP | |
8280 | 4 arguments | |
8281 | If the first argument is \fB!\fP, the result is the negation of | |
8282 | the three-argument expression composed of the remaining arguments. | |
8283 | Otherwise, the expression is parsed and evaluated according to | |
8284 | precedence using the rules listed above. | |
8285 | .TP | |
8286 | 5 or more arguments | |
8287 | The expression is parsed and evaluated according to precedence | |
8288 | using the rules listed above. | |
726f6388 | 8289 | .RE |
cce855bc | 8290 | .PD |
726f6388 JA |
8291 | .TP |
8292 | .B times | |
8293 | Print the accumulated user and system times for the shell and | |
8294 | for processes run from the shell. The return status is 0. | |
8295 | .TP | |
61deeb13 | 8296 | \fBtrap\fP [\fB\-lp\fP] [[\fIarg\fP] \fIsigspec\fP ...] |
726f6388 JA |
8297 | The command |
8298 | .I arg | |
8299 | is to be read and executed when the shell receives | |
8300 | signal(s) | |
8301 | .IR sigspec . | |
8302 | If | |
8303 | .I arg | |
61deeb13 | 8304 | is absent (and there is a single \fIsigspec\fP) or |
726f6388 | 8305 | .BR \- , |
61deeb13 CR |
8306 | each specified signal is |
8307 | reset to its original disposition (the value it had | |
d166f048 JA |
8308 | upon entrance to the shell). |
8309 | If | |
726f6388 | 8310 | .I arg |
d166f048 JA |
8311 | is the null string the signal specified by each |
8312 | .I sigspec | |
8313 | is ignored by the shell and by the commands it invokes. | |
ccc6cda3 JA |
8314 | If |
8315 | .I arg | |
bb70624e | 8316 | is not present and |
ccc6cda3 | 8317 | .B \-p |
bb70624e | 8318 | has been supplied, then the trap commands associated with each |
ccc6cda3 | 8319 | .I sigspec |
bb70624e JA |
8320 | are displayed. |
8321 | If no arguments are supplied or if only | |
ccc6cda3 JA |
8322 | .B \-p |
8323 | is given, | |
8324 | .B trap | |
61deeb13 | 8325 | prints the list of commands associated with each signal. |
d3a24ed2 CR |
8326 | The |
8327 | .B \-l | |
8328 | option causes the shell to print a list of signal names and | |
8329 | their corresponding numbers. | |
d166f048 | 8330 | Each |
726f6388 JA |
8331 | .I sigspec |
8332 | is either | |
d166f048 | 8333 | a signal name defined in <\fIsignal.h\fP>, or a signal number. |
61deeb13 | 8334 | Signal names are case insensitive and the SIG prefix is optional. |
d166f048 | 8335 | If a |
726f6388 JA |
8336 | .I sigspec |
8337 | is | |
8338 | .SM | |
8339 | .B EXIT | |
8340 | (0) the command | |
8341 | .I arg | |
f73dda09 JA |
8342 | is executed on exit from the shell. |
8343 | If a | |
ccc6cda3 JA |
8344 | .I sigspec |
8345 | is | |
8346 | .SM | |
8347 | .BR DEBUG , | |
8348 | the command | |
8349 | .I arg | |
d3a24ed2 CR |
8350 | is executed before every \fIsimple command\fP, \fIfor\fP command, |
8351 | \fIcase\fP command, \fIselect\fP command, every arithmetic \fIfor\fP | |
8352 | command, and before the first command executes in a shell function (see | |
ccc6cda3 JA |
8353 | .SM |
8354 | .B SHELL GRAMMAR | |
8355 | above). | |
40b074c6 | 8356 | Refer to the description of the \fBextdebug\fP option to the |
d3a24ed2 | 8357 | \fBshopt\fP builtin for details of its effect on the \fBDEBUG\fP trap. |
f73dda09 JA |
8358 | If a |
8359 | .I sigspec | |
8360 | is | |
8361 | .SM | |
8362 | .BR ERR , | |
8363 | the command | |
8364 | .I arg | |
5e13499c CR |
8365 | is executed whenever a simple command has a non\-zero exit status, |
8366 | subject to the following conditions. | |
f73dda09 JA |
8367 | The |
8368 | .SM | |
d3a24ed2 CR |
8369 | .B ERR |
8370 | trap is not executed if the failed | |
8371 | command is part of the command list immediately following a | |
8372 | .B while | |
f73dda09 | 8373 | or |
d3a24ed2 CR |
8374 | .B until |
8375 | keyword, | |
8376 | part of the test in an | |
f73dda09 JA |
8377 | .I if |
8378 | statement, part of a | |
8379 | .B && | |
8380 | or | |
8381 | .B \(bv\(bv | |
8382 | list, or if the command's return value is | |
8383 | being inverted via | |
8384 | .BR ! . | |
5e13499c | 8385 | These are the same conditions obeyed by the \fBerrexit\fP option. |
d3a24ed2 CR |
8386 | If a |
8387 | .I sigspec | |
8388 | is | |
8389 | .SM | |
8390 | .BR RETURN , | |
8391 | the command | |
8392 | .I arg | |
8393 | is executed each time a shell function or a script executed with the | |
8394 | \fB.\fP or \fBsource\fP builtins finishes executing. | |
726f6388 JA |
8395 | Signals ignored upon entry to the shell cannot be trapped or reset. |
8396 | Trapped signals are reset to their original values in a child | |
d166f048 JA |
8397 | process when it is created. |
8398 | The return status is false if any | |
ccc6cda3 JA |
8399 | .I sigspec |
8400 | is invalid; otherwise | |
726f6388 JA |
8401 | .B trap |
8402 | returns true. | |
8403 | .TP | |
7117c2d2 | 8404 | \fBtype\fP [\fB\-aftpP\fP] \fIname\fP [\fIname\fP ...] |
726f6388 JA |
8405 | With no options, |
8406 | indicate how each | |
8407 | .I name | |
8408 | would be interpreted if used as a command name. | |
8409 | If the | |
cce855bc JA |
8410 | .B \-t |
8411 | option is used, | |
726f6388 | 8412 | .B type |
ccc6cda3 | 8413 | prints a string which is one of |
726f6388 JA |
8414 | .IR alias , |
8415 | .IR keyword , | |
8416 | .IR function , | |
8417 | .IR builtin , | |
8418 | or | |
8419 | .I file | |
8420 | if | |
8421 | .I name | |
8422 | is an alias, shell reserved word, function, builtin, or disk file, | |
ccc6cda3 JA |
8423 | respectively. |
8424 | If the | |
8425 | .I name | |
8426 | is not found, then nothing is printed, and an exit status of false | |
8427 | is returned. | |
726f6388 | 8428 | If the |
cce855bc JA |
8429 | .B \-p |
8430 | option is used, | |
726f6388 JA |
8431 | .B type |
8432 | either returns the name of the disk file | |
8433 | that would be executed if | |
8434 | .I name | |
8435 | were specified as a command name, | |
28ef6c31 JA |
8436 | or nothing if |
8437 | .if t \f(CWtype -t name\fP | |
8438 | .if n ``type -t name'' | |
726f6388 JA |
8439 | would not return |
8440 | .IR file . | |
7117c2d2 JA |
8441 | The |
8442 | .B \-P | |
8443 | option forces a | |
8444 | .SM | |
8445 | .B PATH | |
8446 | search for each \fIname\fP, even if | |
8447 | .if t \f(CWtype -t name\fP | |
8448 | .if n ``type -t name'' | |
8449 | would not return | |
8450 | .IR file . | |
726f6388 | 8451 | If a command is hashed, |
cce855bc | 8452 | .B \-p |
7117c2d2 JA |
8453 | and |
8454 | .B \-P | |
8455 | print the hashed value, not necessarily the file that appears | |
726f6388 JA |
8456 | first in |
8457 | .SM | |
8458 | .BR PATH . | |
8459 | If the | |
cce855bc JA |
8460 | .B \-a |
8461 | option is used, | |
726f6388 JA |
8462 | .B type |
8463 | prints all of the places that contain | |
8464 | an executable named | |
8465 | .IR name . | |
8466 | This includes aliases and functions, | |
8467 | if and only if the | |
cce855bc JA |
8468 | .B \-p |
8469 | option is not also used. | |
726f6388 JA |
8470 | The table of hashed commands is not consulted |
8471 | when using | |
cce855bc | 8472 | .BR \-a . |
7117c2d2 JA |
8473 | The |
8474 | .B \-f | |
8475 | option suppresses shell function lookup, as with the \fBcommand\fP builtin. | |
726f6388 JA |
8476 | .B type |
8477 | returns true if any of the arguments are found, false if | |
8478 | none are found. | |
8479 | .TP | |
ccc6cda3 JA |
8480 | \fBulimit\fP [\fB\-SHacdflmnpstuv\fP [\fIlimit\fP]] |
8481 | Provides control over the resources available to the shell and to | |
f73dda09 | 8482 | processes started by it, on systems that allow such control. |
ccc6cda3 | 8483 | The \fB\-H\fP and \fB\-S\fP options specify that the hard or soft limit is |
726f6388 JA |
8484 | set for the given resource. A hard limit cannot be increased once it |
8485 | is set; a soft limit may be increased up to the value of the hard limit. | |
ccc6cda3 JA |
8486 | If neither \fB\-H\fP nor \fB\-S\fP is specified, both the soft and hard |
8487 | limits are set. | |
f73dda09 JA |
8488 | The value of |
8489 | .I limit | |
8490 | can be a number in the unit specified for the resource | |
8491 | or one of the special values | |
8492 | .BR hard , | |
8493 | .BR soft , | |
8494 | or | |
8495 | .BR unlimited , | |
8496 | which stand for the current hard limit, the current soft limit, and | |
8497 | no limit, respectively. | |
ccc6cda3 | 8498 | If |
726f6388 JA |
8499 | .I limit |
8500 | is omitted, the current value of the soft limit of the resource is | |
ccc6cda3 JA |
8501 | printed, unless the \fB\-H\fP option is given. When more than one |
8502 | resource is specified, the limit name and unit are printed before the value. | |
726f6388 JA |
8503 | Other options are interpreted as follows: |
8504 | .RS | |
8505 | .PD 0 | |
8506 | .TP | |
8507 | .B \-a | |
ccc6cda3 | 8508 | All current limits are reported |
726f6388 JA |
8509 | .TP |
8510 | .B \-c | |
ccc6cda3 | 8511 | The maximum size of core files created |
726f6388 JA |
8512 | .TP |
8513 | .B \-d | |
ccc6cda3 | 8514 | The maximum size of a process's data segment |
726f6388 JA |
8515 | .TP |
8516 | .B \-f | |
ccc6cda3 | 8517 | The maximum size of files created by the shell |
726f6388 | 8518 | .TP |
ccc6cda3 JA |
8519 | .B \-l |
8520 | The maximum size that may be locked into memory | |
726f6388 | 8521 | .TP |
ccc6cda3 JA |
8522 | .B \-m |
8523 | The maximum resident set size | |
726f6388 | 8524 | .TP |
ccc6cda3 JA |
8525 | .B \-n |
8526 | The maximum number of open file descriptors (most systems do not | |
8527 | allow this value to be set) | |
726f6388 JA |
8528 | .TP |
8529 | .B \-p | |
ccc6cda3 | 8530 | The pipe size in 512-byte blocks (this may not be set) |
726f6388 | 8531 | .TP |
ccc6cda3 JA |
8532 | .B \-s |
8533 | The maximum stack size | |
8534 | .TP | |
8535 | .B \-t | |
8536 | The maximum amount of cpu time in seconds | |
726f6388 JA |
8537 | .TP |
8538 | .B \-u | |
ccc6cda3 | 8539 | The maximum number of processes available to a single user |
726f6388 JA |
8540 | .TP |
8541 | .B \-v | |
8542 | The maximum amount of virtual memory available to the shell | |
8543 | .PD | |
8544 | .PP | |
ccc6cda3 | 8545 | If |
726f6388 JA |
8546 | .I limit |
8547 | is given, it is the new value of the specified resource (the | |
8548 | .B \-a | |
8549 | option is display only). | |
8550 | If no option is given, then | |
8551 | .B \-f | |
8552 | is assumed. Values are in 1024-byte increments, except for | |
8553 | .BR \-t , | |
8554 | which is in seconds, | |
8555 | .BR \-p , | |
8556 | which is in units of 512-byte blocks, | |
8557 | and | |
8558 | .B \-n | |
8559 | and | |
8560 | .BR \-u , | |
f73dda09 JA |
8561 | which are unscaled values. |
8562 | The return status is 0 unless an invalid option or argument is supplied, | |
8563 | or an error occurs while setting a new limit. | |
726f6388 JA |
8564 | .RE |
8565 | .TP | |
cce855bc | 8566 | \fBumask\fP [\fB\-p\fP] [\fB\-S\fP] [\fImode\fP] |
726f6388 JA |
8567 | The user file-creation mask is set to |
8568 | .IR mode . | |
8569 | If | |
8570 | .I mode | |
8571 | begins with a digit, it | |
8572 | is interpreted as an octal number; otherwise | |
8573 | it is interpreted as a symbolic mode mask similar | |
8574 | to that accepted by | |
8575 | .IR chmod (1). | |
8576 | If | |
8577 | .I mode | |
bb70624e | 8578 | is omitted, the current value of the mask is printed. |
ccc6cda3 | 8579 | The |
726f6388 JA |
8580 | .B \-S |
8581 | option causes the mask to be printed in symbolic form; the | |
8582 | default output is an octal number. | |
cce855bc JA |
8583 | If the |
8584 | .B \-p | |
8585 | option is supplied, and | |
8586 | .I mode | |
8587 | is omitted, the output is in a form that may be reused as input. | |
ccc6cda3 | 8588 | The return status is 0 if the mode was successfully changed or if |
726f6388 JA |
8589 | no \fImode\fP argument was supplied, and false otherwise. |
8590 | .TP | |
8591 | \fBunalias\fP [\-\fBa\fP] [\fIname\fP ...] | |
bb70624e | 8592 | Remove each \fIname\fP from the list of defined aliases. If |
726f6388 JA |
8593 | .B \-a |
8594 | is supplied, all alias definitions are removed. The return | |
8595 | value is true unless a supplied | |
8596 | .I name | |
8597 | is not a defined alias. | |
8598 | .TP | |
8599 | \fBunset\fP [\-\fBfv\fP] [\fIname\fP ...] | |
8600 | For each | |
8601 | .IR name , | |
ccc6cda3 JA |
8602 | remove the corresponding variable or function. |
8603 | If no options are supplied, or the | |
8604 | .B \-v | |
8605 | option is given, each | |
8606 | .I name | |
8607 | refers to a shell variable. | |
8608 | Read-only variables may not be unset. | |
8609 | If | |
726f6388 | 8610 | .B \-f |
f75912ae | 8611 | is specified, each |
ccc6cda3 JA |
8612 | .I name |
8613 | refers to a shell function, and the function definition | |
8614 | is removed. | |
8615 | Each unset variable or function is removed from the environment | |
8616 | passed to subsequent commands. | |
8617 | If any of | |
726f6388 JA |
8618 | .SM |
8619 | .BR RANDOM , | |
8620 | .SM | |
8621 | .BR SECONDS , | |
8622 | .SM | |
8623 | .BR LINENO , | |
ccc6cda3 JA |
8624 | .SM |
8625 | .BR HISTCMD , | |
bb70624e JA |
8626 | .SM |
8627 | .BR FUNCNAME , | |
8628 | .SM | |
8629 | .BR GROUPS , | |
726f6388 JA |
8630 | or |
8631 | .SM | |
ccc6cda3 | 8632 | .B DIRSTACK |
726f6388 JA |
8633 | are unset, they lose their special properties, even if they are |
8634 | subsequently reset. The exit status is true unless a | |
8635 | .I name | |
d3a24ed2 | 8636 | is readonly. |
726f6388 | 8637 | .TP |
d90269dd CR |
8638 | \fBwait\fP [\fIn ...\fP] |
8639 | Wait for each specified process and return its termination status. | |
8640 | Each | |
726f6388 JA |
8641 | .I n |
8642 | may be a process | |
8643 | ID or a job specification; if a job spec is given, all processes | |
8644 | in that job's pipeline are waited for. If | |
8645 | .I n | |
8646 | is not given, all currently active child processes | |
8647 | are waited for, and the return status is zero. If | |
8648 | .I n | |
ccc6cda3 | 8649 | specifies a non-existent process or job, the return status is |
726f6388 JA |
8650 | 127. Otherwise, the return status is the exit status of the last |
8651 | process or job waited for. | |
8652 | .\" bash_builtins | |
8653 | .if \n(zZ=1 .ig zZ | |
ccc6cda3 | 8654 | .SH "RESTRICTED SHELL" |
bb70624e JA |
8655 | .\" rbash.1 |
8656 | .zY | |
726f6388 | 8657 | .PP |
ccc6cda3 | 8658 | If |
726f6388 | 8659 | .B bash |
ccc6cda3 JA |
8660 | is started with the name |
8661 | .BR rbash , | |
8662 | or the | |
8663 | .B \-r | |
8664 | option is supplied at invocation, | |
8665 | the shell becomes restricted. | |
8666 | A restricted shell is used to | |
8667 | set up an environment more controlled than the standard shell. | |
8668 | It behaves identically to | |
8669 | .B bash | |
cce855bc | 8670 | with the exception that the following are disallowed or not performed: |
ccc6cda3 JA |
8671 | .IP \(bu |
8672 | changing directories with \fBcd\fP | |
8673 | .IP \(bu | |
8674 | setting or unsetting the values of | |
b72432fd JA |
8675 | .BR SHELL , |
8676 | .BR PATH , | |
8677 | .BR ENV , | |
ccc6cda3 | 8678 | or |
b72432fd | 8679 | .B BASH_ENV |
ccc6cda3 JA |
8680 | .IP \(bu |
8681 | specifying command names containing | |
8682 | .B / | |
8683 | .IP \(bu | |
8684 | specifying a file name containing a | |
8685 | .B / | |
8686 | as an argument to the | |
8687 | .B . | |
8688 | builtin command | |
8689 | .IP \(bu | |
bb70624e JA |
8690 | Specifying a filename containing a slash as an argument to the |
8691 | .B \-p | |
8692 | option to the | |
8693 | .B hash | |
8694 | builtin command | |
8695 | .IP \(bu | |
ccc6cda3 JA |
8696 | importing function definitions from the shell environment at startup |
8697 | .IP \(bu | |
cce855bc JA |
8698 | parsing the value of \fBSHELLOPTS\fP from the shell environment at startup |
8699 | .IP \(bu | |
ccc6cda3 JA |
8700 | redirecting output using the >, >|, <>, >&, &>, and >> redirection operators |
8701 | .IP \(bu | |
8702 | using the | |
8703 | .B exec | |
8704 | builtin command to replace the shell with another command | |
8705 | .IP \(bu | |
8706 | adding or deleting builtin commands with the | |
8707 | .B \-f | |
726f6388 | 8708 | and |
ccc6cda3 JA |
8709 | .B \-d |
8710 | options to the | |
8711 | .B enable | |
8712 | builtin command | |
8713 | .IP \(bu | |
7117c2d2 JA |
8714 | Using the \fBenable\fP builtin command to enable disabled shell builtins |
8715 | .IP \(bu | |
ccc6cda3 JA |
8716 | specifying the |
8717 | .B \-p | |
8718 | option to the | |
8719 | .B command | |
8720 | builtin command | |
8721 | .IP \(bu | |
8722 | turning off restricted mode with | |
cce855bc | 8723 | \fBset +r\fP or \fBset +o restricted\fP. |
726f6388 | 8724 | .PP |
ccc6cda3 JA |
8725 | These restrictions are enforced after any startup files are read. |
8726 | .PP | |
61deeb13 CR |
8727 | .ie \n(zY=1 When a command that is found to be a shell script is executed, |
8728 | .el \{ When a command that is found to be a shell script is executed | |
8729 | (see | |
ccc6cda3 JA |
8730 | .SM |
8731 | .B "COMMAND EXECUTION" | |
8732 | above), | |
61deeb13 | 8733 | \} |
ccc6cda3 JA |
8734 | .B rbash |
8735 | turns off any restrictions in the shell spawned to execute the | |
8736 | script. | |
bb70624e JA |
8737 | .\" end of rbash.1 |
8738 | .if \n(zY=1 .ig zY | |
726f6388 JA |
8739 | .SH "SEE ALSO" |
8740 | .PD 0 | |
8741 | .TP | |
bb70624e | 8742 | \fIBash Reference Manual\fP, Brian Fox and Chet Ramey |
726f6388 JA |
8743 | .TP |
8744 | \fIThe Gnu Readline Library\fP, Brian Fox and Chet Ramey | |
8745 | .TP | |
8746 | \fIThe Gnu History Library\fP, Brian Fox and Chet Ramey | |
8747 | .TP | |
726f6388 JA |
8748 | \fIPortable Operating System Interface (POSIX) Part 2: Shell and Utilities\fP, IEEE |
8749 | .TP | |
8750 | \fIsh\fP(1), \fIksh\fP(1), \fIcsh\fP(1) | |
8751 | .TP | |
8752 | \fIemacs\fP(1), \fIvi\fP(1) | |
8753 | .TP | |
8754 | \fIreadline\fP(3) | |
8755 | .PD | |
8756 | .SH FILES | |
8757 | .PD 0 | |
8758 | .TP | |
8759 | .FN /bin/bash | |
8760 | The \fBbash\fP executable | |
8761 | .TP | |
8762 | .FN /etc/profile | |
8763 | The systemwide initialization file, executed for login shells | |
8764 | .TP | |
8765 | .FN ~/.bash_profile | |
8766 | The personal initialization file, executed for login shells | |
8767 | .TP | |
8768 | .FN ~/.bashrc | |
8769 | The individual per-interactive-shell startup file | |
8770 | .TP | |
b72432fd JA |
8771 | .FN ~/.bash_logout |
8772 | The individual login shell cleanup file, executed when a login shell exits | |
8773 | .TP | |
726f6388 JA |
8774 | .FN ~/.inputrc |
8775 | Individual \fIreadline\fP initialization file | |
8776 | .PD | |
8777 | .SH AUTHORS | |
ccc6cda3 | 8778 | Brian Fox, Free Software Foundation |
726f6388 | 8779 | .br |
bb70624e | 8780 | bfox@gnu.org |
726f6388 JA |
8781 | .PP |
8782 | Chet Ramey, Case Western Reserve University | |
8783 | .br | |
d3a24ed2 | 8784 | chet@po.CWRU.Edu |
726f6388 JA |
8785 | .SH BUG REPORTS |
8786 | If you find a bug in | |
8787 | .B bash, | |
8788 | you should report it. But first, you should | |
8789 | make sure that it really is a bug, and that it appears in the latest | |
8790 | version of | |
d3a24ed2 CR |
8791 | .BR bash . |
8792 | The latest version is always available from | |
8793 | \fIftp://ftp.gnu.org/pub/bash/\fP. | |
726f6388 JA |
8794 | .PP |
8795 | Once you have determined that a bug actually exists, use the | |
8796 | .I bashbug | |
8797 | command to submit a bug report. | |
d166f048 | 8798 | If you have a fix, you are encouraged to mail that as well! |
726f6388 | 8799 | Suggestions and `philosophical' bug reports may be mailed |
cce855bc | 8800 | to \fIbug-bash@gnu.org\fP or posted to the Usenet |
726f6388 JA |
8801 | newsgroup |
8802 | .BR gnu.bash.bug . | |
8803 | .PP | |
8804 | ALL bug reports should include: | |
8805 | .PP | |
8806 | .PD 0 | |
8807 | .TP 20 | |
8808 | The version number of \fBbash\fR | |
8809 | .TP | |
8810 | The hardware and operating system | |
8811 | .TP | |
8812 | The compiler used to compile | |
8813 | .TP | |
8814 | A description of the bug behaviour | |
8815 | .TP | |
8816 | A short script or `recipe' which exercises the bug | |
8817 | .PD | |
8818 | .PP | |
8819 | .I bashbug | |
8820 | inserts the first three items automatically into the template | |
8821 | it provides for filing a bug report. | |
8822 | .PP | |
8823 | Comments and bug reports concerning | |
8824 | this manual page should be directed to | |
d3a24ed2 | 8825 | .IR chet@po.CWRU.Edu . |
726f6388 JA |
8826 | .SH BUGS |
8827 | .PP | |
8828 | It's too big and too slow. | |
8829 | .PP | |
8830 | There are some subtle differences between | |
8831 | .B bash | |
8832 | and traditional versions of | |
8833 | .BR sh , | |
8834 | mostly because of the | |
8835 | .SM | |
8836 | .B POSIX | |
8837 | specification. | |
8838 | .PP | |
8839 | Aliases are confusing in some uses. | |
ccc6cda3 JA |
8840 | .PP |
8841 | Shell builtin commands and functions are not stoppable/restartable. | |
8842 | .PP | |
8843 | Compound commands and command sequences of the form `a ; b ; c' | |
8844 | are not handled gracefully when process suspension is attempted. | |
8845 | When a process is stopped, the shell immediately executes the next | |
8846 | command in the sequence. | |
8847 | It suffices to place the sequence of commands between | |
8848 | parentheses to force it into a subshell, which may be stopped as | |
8849 | a unit. | |
8850 | .PP | |
8851 | Commands inside of \fB$(\fP...\fB)\fP command substitution are not | |
8852 | parsed until substitution is attempted. This will delay error | |
704a1a2a CR |
8853 | reporting until some time after the command is entered. For example, |
8854 | unmatched parentheses, even inside shell comments, will result in | |
8855 | error messages while the construct is being read. | |
ccc6cda3 JA |
8856 | .PP |
8857 | Array variables may not (yet) be exported. | |
726f6388 | 8858 | .zZ |
bb70624e | 8859 | .zY |