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726f6388 JA |
1 | .\" |
2 | .\" MAN PAGE COMMENTS to | |
3 | .\" | |
4 | .\" Chet Ramey | |
5 | .\" Information Network Services | |
6 | .\" Case Western Reserve University | |
7 | .\" chet@ins.CWRU.Edu | |
8 | .\" | |
bb70624e | 9 | .\" Last Change: Tue Mar 14 11:36:43 EST 2000 |
726f6388 JA |
10 | .\" |
11 | .\" bash_builtins, strip all but Built-Ins section | |
12 | .if \n(zZ=1 .ig zZ | |
bb70624e JA |
13 | .if \n(zY=1 .ig zY |
14 | .TH BASH 1 "2000 Mar 14" "GNU Bash-2.04" | |
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 | |
b72432fd JA |
54 | .if n Bash is Copyright (C) 1989-1999 by the Free Software Foundation, Inc. |
55 | .if t Bash is Copyright \(co 1989-1999 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 $0 . | |
83 | .TP | |
ccc6cda3 JA |
84 | .B \-r |
85 | If the | |
86 | .B \-r | |
cce855bc | 87 | option is present, the shell becomes |
ccc6cda3 JA |
88 | .I restricted |
89 | (see | |
90 | .SM | |
91 | .B "RESTRICTED SHELL" | |
92 | below). | |
93 | .TP | |
726f6388 JA |
94 | .B \-i |
95 | If the | |
96 | .B \-i | |
cce855bc | 97 | option is present, the shell is |
726f6388 JA |
98 | .IR interactive . |
99 | .TP | |
100 | .B \-s | |
101 | If the | |
102 | .B \-s | |
cce855bc | 103 | option is present, or if no arguments remain after option |
726f6388 JA |
104 | processing, then commands are read from the standard input. |
105 | This option allows the positional parameters to be set | |
106 | when invoking an interactive shell. | |
107 | .TP | |
ccc6cda3 JA |
108 | .B \-D |
109 | A list of all double-quoted strings preceded by \fB$\fP | |
110 | is printed on the standard ouput. | |
111 | These are the strings that | |
112 | are subject to language translation when the current locale | |
113 | is not C or POSIX. | |
114 | This implies the \fB\-n\fP option; no commands will be executed. | |
115 | .TP | |
116 | .B \-\- | |
117 | A | |
118 | .B \-\- | |
726f6388 JA |
119 | signals the end of options and disables further option processing. |
120 | Any arguments after the | |
726f6388 | 121 | .B \-\- |
ccc6cda3 JA |
122 | are treated as filenames and arguments. An argument of |
123 | .B \- | |
124 | is equivalent to \fB\-\-\fP. | |
726f6388 JA |
125 | .PD |
126 | .PP | |
127 | .B Bash | |
ccc6cda3 JA |
128 | also interprets a number of multi-character options. |
129 | These options must appear on the command line before the | |
130 | single-character options in order for them to be recognized. | |
726f6388 JA |
131 | .PP |
132 | .PD 0 | |
726f6388 | 133 | .TP |
cce855bc JA |
134 | .B \-\-dump\-po\-strings |
135 | Equivalent to \fB\-D\fP, but the output is in the GNU \fIgettext\fP | |
136 | \fBpo\fP (portable object) file format. | |
137 | .TP | |
ccc6cda3 JA |
138 | .B \-\-dump\-strings |
139 | Equivalent to \fB\-D\fP. | |
140 | .TP | |
141 | .B \-\-help | |
142 | Display a usage message on standard output and exit successfully. | |
143 | .TP | |
144 | .B \-\-login | |
145 | Make | |
146 | .B bash | |
147 | act as if it had been invoked as a login shell (see | |
148 | .SM | |
149 | .B INVOCATION | |
150 | below). | |
151 | .TP | |
152 | .B \-\-noediting | |
153 | Do not use the GNU | |
154 | .B readline | |
bb70624e | 155 | library to read command lines when the shell is interactive. |
ccc6cda3 JA |
156 | .TP |
157 | .B \-\-noprofile | |
158 | Do not read either the system-wide startup file | |
726f6388 JA |
159 | .FN /etc/profile |
160 | or any of the personal initialization files | |
161 | .IR ~/.bash_profile , | |
162 | .IR ~/.bash_login , | |
163 | or | |
164 | .IR ~/.profile . | |
165 | By default, | |
166 | .B bash | |
ccc6cda3 | 167 | reads these files when it is invoked as a login shell (see |
726f6388 JA |
168 | .SM |
169 | .B INVOCATION | |
170 | below). | |
171 | .TP | |
ccc6cda3 JA |
172 | .B \-\-norc |
173 | Do not read and execute the personal initialization file | |
174 | .I ~/.bashrc | |
175 | if the shell is interactive. | |
176 | This option is on by default if the shell is invoked as | |
177 | .BR sh . | |
178 | .TP | |
179 | .B \-\-posix | |
180 | Change the behavior of \fBbash\fP where the default operation differs | |
181 | from the POSIX 1003.2 standard to match the standard. | |
182 | .TP | |
183 | \fB\-\-rcfile\fP \fIfile\fP | |
726f6388 JA |
184 | Execute commands from |
185 | .I file | |
186 | instead of the standard personal initialization file | |
ccc6cda3 | 187 | .I ~/.bashrc |
726f6388 JA |
188 | if the shell is interactive (see |
189 | .SM | |
190 | .B INVOCATION | |
191 | below). | |
192 | .TP | |
ccc6cda3 JA |
193 | .B \-\-restricted |
194 | The shell becomes restricted (see | |
195 | .SM | |
196 | .B "RESTRICTED SHELL" | |
726f6388 JA |
197 | below). |
198 | .TP | |
ccc6cda3 JA |
199 | .B \-\-verbose |
200 | Equivalent to \fB\-v\fP. | |
726f6388 | 201 | .TP |
ccc6cda3 JA |
202 | .B \-\-version |
203 | Show version information for this instance of | |
204 | .B bash | |
205 | on the standard output and exit successfully. | |
726f6388 JA |
206 | .PD |
207 | .SH ARGUMENTS | |
208 | If arguments remain after option processing, and neither the | |
209 | .B \-c | |
210 | nor the | |
211 | .B \-s | |
212 | option has been supplied, the first argument is assumed to | |
ccc6cda3 JA |
213 | be the name of a file containing shell commands. |
214 | If | |
726f6388 JA |
215 | .B bash |
216 | is invoked in this fashion, | |
217 | .B $0 | |
218 | is set to the name of the file, and the positional parameters | |
219 | are set to the remaining arguments. | |
220 | .B Bash | |
221 | reads and executes commands from this file, then exits. | |
ccc6cda3 JA |
222 | \fBBash\fP's exit status is the exit status of the last command |
223 | executed in the script. | |
224 | If no commands are executed, the exit status is 0. | |
225 | .SH INVOCATION | |
226 | A \fIlogin shell\fP is one whose first character of argument zero is a | |
227 | .BR \- , | |
228 | or one started with the | |
229 | .B \-\-login | |
230 | option. | |
231 | .PP | |
bb70624e JA |
232 | An \fIinteractive\fP shell is one started without non-option arguments |
233 | and without the | |
234 | .B \-c | |
235 | option | |
236 | whose standard input and output are | |
ccc6cda3 JA |
237 | both connected to terminals (as determined by |
238 | .IR isatty (3)), | |
239 | or one started with the | |
240 | .B \-i | |
241 | option. | |
242 | .SM | |
243 | .B PS1 | |
244 | is set and | |
245 | .B $\- | |
246 | includes | |
247 | .B i | |
248 | if | |
249 | .B bash | |
250 | is interactive, | |
251 | allowing a shell script or a startup file to test this state. | |
252 | .PP | |
253 | The following paragraphs describe how | |
254 | .B bash | |
255 | executes its startup files. | |
256 | If any of the files exist but cannot be read, | |
257 | .B bash | |
258 | reports an error. | |
259 | Tildes are expanded in file names as described below under | |
260 | .B "Tilde Expansion" | |
261 | in the | |
262 | .SM | |
263 | .B EXPANSION | |
264 | section. | |
265 | .PP | |
266 | When | |
267 | .B bash | |
b72432fd JA |
268 | is invoked as an interactive login shell, or as a non-interactive shell |
269 | with the \fB\-\-login\fP option, it first reads and | |
d166f048 JA |
270 | executes commands from the file \fI/etc/profile\fP, if that |
271 | file exists. | |
ccc6cda3 JA |
272 | After reading that file, it looks for \fI~/.bash_profile\fP, |
273 | \fI~/.bash_login\fP, and \fI~/.profile\fP, in that order, and reads | |
274 | and executes commands from the first one that exists and is readable. | |
275 | The | |
276 | .B \-\-noprofile | |
277 | option may be used when the shell is started to inhibit this behavior. | |
278 | .PP | |
279 | When a login shell exits, | |
280 | .B bash | |
281 | reads and executes commands from the file \fI~/.bash_logout\fP, if it | |
282 | exists. | |
283 | .PP | |
284 | When an interactive shell that is not a login shell is started, | |
285 | .B bash | |
286 | reads and executes commands from \fI~/.bashrc\fP, if that file exists. | |
287 | This may be inhibited by using the | |
288 | .B \-\-norc | |
289 | option. | |
290 | The \fB\-\-rcfile\fP \fIfile\fP option will force | |
291 | .B bash | |
292 | to read and execute commands from \fIfile\fP instead of \fI~/.bashrc\fP. | |
293 | .PP | |
294 | When | |
295 | .B bash | |
296 | is started non-interactively, to run a shell script, for example, it | |
297 | looks for the variable | |
298 | .SM | |
299 | .B BASH_ENV | |
300 | in the environment, expands its value if it appears there, and uses the | |
301 | expanded value as the name of a file to read and execute. | |
302 | .B Bash | |
303 | behaves as if the following command were executed: | |
304 | .sp .5 | |
305 | .RS | |
306 | \f(CWif [ \-n "$BASH_ENV" ]; then . "$BASH_ENV"; fi\fP | |
307 | .RE | |
308 | .sp .5 | |
309 | but the value of the | |
310 | .SM | |
311 | .B PATH | |
312 | variable is not used to search for the file name. | |
313 | .PP | |
314 | If | |
315 | .B bash | |
316 | is invoked with the name | |
317 | .BR sh , | |
318 | it tries to mimic the startup behavior of historical versions of | |
319 | .B sh | |
320 | as closely as possible, | |
321 | while conforming to the POSIX standard as well. | |
b72432fd JA |
322 | When invoked as an interactive login shell, or a non-interactive |
323 | shell with the \fB\-\-login\fP option, it first attempts to | |
cce855bc | 324 | read and execute commands from |
ccc6cda3 JA |
325 | .I /etc/profile |
326 | and | |
327 | .IR ~/.profile , | |
328 | in that order. | |
329 | The | |
330 | .B \-\-noprofile | |
331 | option may be used to inhibit this behavior. | |
332 | When invoked as an interactive shell with the name | |
333 | .BR sh , | |
334 | .B bash | |
335 | looks for the variable | |
336 | .SM | |
337 | .BR ENV , | |
338 | expands its value if it is defined, and uses the | |
339 | expanded value as the name of a file to read and execute. | |
340 | Since a shell invoked as | |
341 | .B sh | |
342 | does not attempt to read and execute commands from any other startup | |
343 | files, the | |
344 | .B \-\-rcfile | |
345 | option has no effect. | |
346 | A non-interactive shell invoked with the name | |
347 | .B sh | |
b72432fd | 348 | does not attempt to read any other startup files. |
ccc6cda3 JA |
349 | When invoked as |
350 | .BR sh , | |
351 | .B bash | |
352 | enters | |
353 | .I posix | |
354 | mode after the startup files are read. | |
355 | .PP | |
356 | When | |
357 | .B bash | |
358 | is started in | |
359 | .I posix | |
360 | mode, as with the | |
361 | .B \-\-posix | |
362 | command line option, it follows the POSIX standard for startup files. | |
cce855bc | 363 | In this mode, interactive shells expand the |
ccc6cda3 JA |
364 | .SM |
365 | .B ENV | |
cce855bc | 366 | variable and commands are read and executed from the file |
ccc6cda3 JA |
367 | whose name is the expanded value. |
368 | No other startup files are read. | |
ccc6cda3 JA |
369 | .PP |
370 | .B Bash | |
371 | attempts to determine when it is being run by the remote shell | |
372 | daemon, usually \fIrshd\fP. | |
373 | If | |
374 | .B bash | |
375 | determines it is being run by \fIrshd\fP, it reads and executes | |
376 | commands from \fI~/.bashrc\fP, if that file exists and is readable. | |
377 | It will not do this if invoked as \fBsh\fP. | |
378 | The | |
379 | .B \-\-norc | |
380 | option may be used to inhibit this behavior, and the | |
381 | .B \-\-rcfile | |
382 | option may be used to force another file to be read, but | |
383 | \fIrshd\fP does not generally invoke the shell with those options | |
384 | or allow them to be specified. | |
b72432fd JA |
385 | .PP |
386 | If the shell is started with the effective user (group) id not equal to the | |
387 | real user (group) id, and the \fB\-p\fP option is not supplied, no startup | |
388 | files are read, shell functions are not inherited from the environment, | |
389 | the \fBSHELLOPTS\fP variable, if it appears in the environment, is ignored, | |
390 | and the effective user id is set to the real user id. | |
391 | If the \fB\-p\fP option is supplied at invocation, the startup behavior is | |
392 | the same, but the effective user id is not reset. | |
726f6388 | 393 | .SH DEFINITIONS |
ccc6cda3 JA |
394 | .PP |
395 | The following definitions are used throughout the rest of this | |
396 | document. | |
726f6388 JA |
397 | .PD 0 |
398 | .TP | |
399 | .B blank | |
400 | A space or tab. | |
401 | .TP | |
402 | .B word | |
403 | A sequence of characters considered as a single unit by the shell. | |
404 | Also known as a | |
405 | .BR token . | |
406 | .TP | |
407 | .B name | |
408 | A | |
409 | .I word | |
410 | consisting only of alphanumeric characters and underscores, and | |
411 | beginning with an alphabetic character or an underscore. Also | |
412 | referred to as an | |
413 | .BR identifier . | |
414 | .TP | |
415 | .B metacharacter | |
416 | A character that, when unquoted, separates words. One of the following: | |
417 | .br | |
418 | .RS | |
419 | .PP | |
420 | .if t \fB| & ; ( ) < > space tab\fP | |
421 | .if n \fB| & ; ( ) < > space tab\fP | |
422 | .RE | |
423 | .PP | |
424 | .TP | |
425 | .B control operator | |
426 | A \fItoken\fP that performs a control function. It is one of the following | |
427 | symbols: | |
428 | .RS | |
429 | .PP | |
ccc6cda3 | 430 | .if t \fB\(bv\(bv & && ; ;; ( ) | <newline>\fP |
726f6388 JA |
431 | .if n \fB|| & && ; ;; ( ) | <newline>\fP |
432 | .RE | |
433 | .PD | |
434 | .SH "RESERVED WORDS" | |
435 | \fIReserved words\fP are words that have a special meaning to the shell. | |
436 | The following words are recognized as reserved when unquoted and either | |
437 | the first word of a simple command (see | |
438 | .SM | |
439 | .B SHELL GRAMMAR | |
440 | below) or the third word of a | |
441 | .B case | |
442 | or | |
443 | .B for | |
444 | command: | |
445 | .if t .RS | |
446 | .PP | |
447 | .B | |
cce855bc JA |
448 | .if n ! case do done elif else esac fi for function if in select then until while { } time [[ ]] |
449 | .if t ! case do done elif else esac fi for function if in select then until while { } time [[ ]] | |
726f6388 JA |
450 | .if t .RE |
451 | .RE | |
452 | .SH "SHELL GRAMMAR" | |
453 | .SS Simple Commands | |
454 | .PP | |
455 | A \fIsimple command\fP is a sequence of optional variable assignments | |
ccc6cda3 | 456 | followed by \fBblank\fP-separated words and redirections, and |
726f6388 JA |
457 | terminated by a \fIcontrol operator\fP. The first word |
458 | specifies the command to be executed. The remaining words are | |
459 | passed as arguments to the invoked command. | |
460 | .PP | |
461 | The return value of a \fIsimple command\fP is its exit status, or | |
462 | 128+\fIn\^\fP if the command is terminated by signal | |
463 | .IR n . | |
464 | .SS Pipelines | |
465 | .PP | |
466 | A \fIpipeline\fP is a sequence of one or more commands separated by | |
467 | the character | |
468 | .BR | . | |
469 | The format for a pipeline is: | |
470 | .RS | |
471 | .PP | |
ccc6cda3 | 472 | [\fBtime\fP [\fB\-p\fP]] [ ! ] \fIcommand\fP [ \fB|\fP \fIcommand2\fP ... ] |
726f6388 JA |
473 | .RE |
474 | .PP | |
475 | The standard output of | |
476 | .I command | |
477 | is connected to the standard input of | |
478 | .IR command2 . | |
479 | This connection is performed before any redirections specified by the | |
480 | command (see | |
481 | .SM | |
482 | .B REDIRECTION | |
483 | below). | |
484 | .PP | |
485 | If the reserved word | |
486 | .B ! | |
487 | precedes a pipeline, the exit status of that | |
488 | pipeline is the logical NOT of the exit status of the last command. | |
489 | Otherwise, the status of the pipeline is the exit status of the last | |
ccc6cda3 JA |
490 | command. |
491 | The shell waits for all commands in the pipeline to | |
726f6388 JA |
492 | terminate before returning a value. |
493 | .PP | |
ccc6cda3 JA |
494 | If the |
495 | .B time | |
496 | reserved word precedes a pipeline, the elapsed as well as user and | |
497 | system time consumed by its execution are reported when the pipeline | |
498 | terminates. | |
499 | The \fB\-p\fP option changes the output format to that specified by POSIX. | |
500 | The | |
501 | .SM | |
502 | .B TIMEFORMAT | |
503 | variable may be set to a format string that specifies how the timing | |
504 | information should be displayed; see the description of | |
505 | .SM | |
506 | .B TIMEFORMAT | |
507 | under | |
508 | .B "Shell Variables" | |
509 | below. | |
510 | .PP | |
726f6388 JA |
511 | Each command in a pipeline is executed as a separate process (i.e., in a |
512 | subshell). | |
513 | .SS Lists | |
514 | .PP | |
515 | A \fIlist\fP is a sequence of one or more pipelines separated by one | |
516 | of the operators | |
517 | .BR ; , | |
518 | .BR & , | |
519 | .BR && , | |
520 | or | |
ccc6cda3 JA |
521 | .BR \(bv\(bv , |
522 | and optionally terminated by one of | |
726f6388 JA |
523 | .BR ; , |
524 | .BR & , | |
525 | or | |
526 | .BR <newline> . | |
527 | .PP | |
528 | Of these list operators, | |
529 | .B && | |
530 | and | |
ccc6cda3 | 531 | .B \(bv\(bv |
726f6388 JA |
532 | have equal precedence, followed by |
533 | .B ; | |
534 | and | |
535 | .BR &, | |
536 | which have equal precedence. | |
537 | .PP | |
538 | If a command is terminated by the control operator | |
539 | .BR & , | |
540 | the shell executes the command in the \fIbackground\fP | |
541 | in a subshell. The shell does not wait for the command to | |
542 | finish, and the return status is 0. Commands separated by a | |
543 | .B ; | |
544 | are executed sequentially; the shell waits for each | |
545 | command to terminate in turn. The return status is the | |
546 | exit status of the last command executed. | |
547 | .PP | |
548 | The control operators | |
549 | .B && | |
550 | and | |
ccc6cda3 | 551 | .B \(bv\(bv |
726f6388 JA |
552 | denote AND lists and OR lists, respectively. |
553 | An AND list has the form | |
554 | .RS | |
555 | .PP | |
bb70624e | 556 | \fIcommand1\fP \fB&&\fP \fIcommand2\fP |
726f6388 JA |
557 | .RE |
558 | .PP | |
559 | .I command2 | |
560 | is executed if, and only if, | |
bb70624e | 561 | .I command1 |
726f6388 JA |
562 | returns an exit status of zero. |
563 | .PP | |
564 | An OR list has the form | |
565 | .RS | |
566 | .PP | |
bb70624e | 567 | \fIcommand1\fP \fB\(bv\(bv\fP \fIcommand2\fP |
726f6388 JA |
568 | .PP |
569 | .RE | |
570 | .PP | |
571 | .I command2 | |
572 | is executed if and only if | |
bb70624e | 573 | .I command1 |
ccc6cda3 | 574 | returns a non-zero exit status. The return status of |
726f6388 JA |
575 | AND and OR lists is the exit status of the last command |
576 | executed in the list. | |
577 | .SS Compound Commands | |
578 | .PP | |
579 | A \fIcompound command\fP is one of the following: | |
580 | .TP | |
581 | (\fIlist\fP) | |
582 | \fIlist\fP is executed in a subshell. Variable assignments and builtin | |
583 | commands that affect the shell's environment do not remain in effect | |
584 | after the command completes. The return status is the exit status of | |
585 | \fIlist\fP. | |
586 | .TP | |
587 | { \fIlist\fP; } | |
ccc6cda3 JA |
588 | \fIlist\fP is simply executed in the current shell environment. |
589 | \fIlist\fP must be terminated with a newline or semicolon. | |
590 | This is known as a \fIgroup command\fP. | |
591 | The return status is the exit status of | |
726f6388 JA |
592 | \fIlist\fP. |
593 | .TP | |
ccc6cda3 JA |
594 | ((\fIexpression\fP)) |
595 | The \fIexpression\fP is evaluated according to the rules described | |
596 | below under | |
597 | .SM | |
598 | .BR "ARITHMETIC EVALUATION" . | |
599 | If the value of the expression is non-zero, the return status is 0; | |
600 | otherwise the return status is 1. This is exactly equivalent to | |
601 | \fBlet "\fIexpression\fP"\fR. | |
602 | .TP | |
cce855bc JA |
603 | \fB[[\fP \fIexpression\fP \fB]]\fP |
604 | Return a status of 0 or 1 depending on the evaluation of | |
605 | the conditional expression \fIexpression\fP. | |
606 | Expressions are composed of the primaries described below under | |
607 | .SM | |
608 | .BR "CONDITIONAL EXPRESSIONS" . | |
609 | Word splitting and pathname expansion are not performed on the words | |
610 | between the \fB[[\fP and \fB]]\fP; tilde expansion, parameter and | |
611 | variable expansion, arithmetic expansion, command substitution, process | |
612 | substitution, and quote removal are performed. | |
613 | .if t .sp 0.5 | |
614 | .if n .sp 1 | |
615 | When the \fB==\fP and \fB!=\fP operators are used, the string to the | |
616 | right of the operator is considered a pattern and matched according | |
617 | to the rules described below under \fBPattern Matching\fP. | |
618 | The return value is 0 if the string matches or does not match | |
619 | the pattern, respectively, and 1 otherwise. | |
620 | Any part of the pattern may be quoted to force it to be matched as a | |
621 | string. | |
622 | .if t .sp 0.5 | |
623 | .if n .sp 1 | |
624 | Expressions may be combined using the following operators, listed | |
625 | in decreasing order of precedence: | |
626 | .if t .sp 0.5 | |
627 | .if n .sp 1 | |
628 | .RS | |
629 | .PD 0 | |
630 | .TP | |
631 | .B ( \fIexpression\fP ) | |
632 | Returns the value of \fIexpression\fP. | |
633 | This may be used to override the normal precedence of operators. | |
634 | .TP | |
635 | .B ! \fIexpression\fP | |
636 | True if | |
637 | .I expression | |
638 | is false. | |
639 | .TP | |
640 | \fIexpression1\fP \fB&&\fP \fIexpression2\fP | |
641 | True if both | |
642 | .I expression1 | |
643 | and | |
644 | .I expression2 | |
645 | are true. | |
646 | .TP | |
647 | .if t \fIexpression1\fP \fB\(bv\(bv\fP \fIexpression2\fP | |
648 | .if n \fIexpression1\fP \fB||\fP \fIexpression2\fP | |
649 | True if either | |
650 | .I expression1 | |
651 | or | |
652 | .I expression2 | |
653 | is true. | |
654 | .PD | |
655 | .RE | |
656 | .LP | |
657 | The \fB&&\fP and | |
658 | .if t \fB\(bv\(bv\fP | |
659 | .if n \fB||\fP | |
660 | operators do not execute \fIexpression2\fP if the value of | |
661 | \fIexpression1\fP is sufficient to determine the return value of | |
662 | the entire conditional expression. | |
663 | .TP | |
b72432fd | 664 | \fBfor\fP \fIname\fP [ \fBin\fP \fIword\fP ] ; \fBdo\fP \fIlist\fP ; \fBdone\fP |
726f6388 | 665 | The list of words following \fBin\fP is expanded, generating a list |
bb70624e JA |
666 | of items. |
667 | The variable \fIname\fP is set to each element of this list | |
668 | in turn, and \fIlist\fP is executed each time. | |
669 | If the \fBin\fP \fIword\fP is omitted, the \fBfor\fP command executes | |
670 | \fIlist\fP once for each positional parameter that is set (see | |
726f6388 JA |
671 | .SM |
672 | .B PARAMETERS | |
673 | below). | |
cce855bc JA |
674 | The return status is the exit status of the last command that executes. |
675 | If the expansion of the items following \fBin\fP results in an empty | |
676 | list, no commands are executed, and the return status is 0. | |
726f6388 | 677 | .TP |
bb70624e JA |
678 | \fBfor\fP (( \fIexpr1\fP ; \fIexpr2\fP ; \fIexpr3\fP )) ; \fBdo\fP \fIlist\fP ; \fBdone\fP |
679 | First, the arithmetic expression \fIexpr1\fP is evaluated according | |
680 | to the rules described below under | |
681 | .SM | |
682 | .BR "ARITHMETIC EVALUATION" . | |
683 | The arithmetic expression \fIexpr2\fP is then evaluated repeatedly | |
684 | until it evaluates to zero. | |
685 | Each time \fIexpr2\fP evaluates to a non-zero value, \fIlist\fP is | |
686 | executed and the arithmetic expression \fIexpr3\fP is evaluated. | |
687 | If any expression is omitted, it behaves as if it evaluates to 1. | |
688 | The return value is the exit status of the last command in \fIlist\fP | |
689 | that is executed, or false if any of the expressions is invalid. | |
690 | .TP | |
b72432fd | 691 | \fBselect\fP \fIname\fP [ \fBin\fP \fIword\fP ] ; \fBdo\fP \fIlist\fP ; \fBdone\fP |
726f6388 JA |
692 | The list of words following \fBin\fP is expanded, generating a list |
693 | of items. The set of expanded words is printed on the standard | |
694 | error, each preceded by a number. If the \fBin\fP | |
695 | \fIword\fP is omitted, the positional parameters are printed (see | |
696 | .SM | |
697 | .B PARAMETERS | |
698 | below). The | |
699 | .B PS3 | |
700 | prompt is then displayed and a line read from the standard input. | |
ccc6cda3 | 701 | If the line consists of a number corresponding to one of |
726f6388 JA |
702 | the displayed words, then the value of |
703 | .I name | |
704 | is set to that word. If the line is empty, the words and prompt | |
705 | are displayed again. If EOF is read, the command completes. Any | |
706 | other value read causes | |
707 | .I name | |
708 | to be set to null. The line read is saved in the variable | |
709 | .BR REPLY . | |
710 | The | |
711 | .I list | |
712 | is executed after each selection until a | |
713 | .B break | |
714 | or | |
715 | .B return | |
716 | command is executed. | |
717 | The exit status of | |
718 | .B select | |
719 | is the exit status of the last command executed in | |
720 | .IR list , | |
721 | or zero if no commands were executed. | |
722 | .TP | |
bb70624e | 723 | \fBcase\fP \fIword\fP \fBin\fP [ [(] \fIpattern\fP [ \fB|\fP \fIpattern\fP ] \ |
726f6388 JA |
724 | ... ) \fIlist\fP ;; ] ... \fBesac\fP |
725 | A \fBcase\fP command first expands \fIword\fP, and tries to match | |
726 | it against each \fIpattern\fP in turn, using the same matching rules | |
727 | as for pathname expansion (see | |
728 | .B Pathname Expansion | |
729 | below). When a match is found, the | |
730 | corresponding \fIlist\fP is executed. After the first match, no | |
731 | subsequent matches are attempted. The exit status is zero if no | |
ccc6cda3 | 732 | pattern matches. Otherwise, it is the exit status of the |
726f6388 JA |
733 | last command executed in \fIlist\fP. |
734 | .TP | |
ccc6cda3 JA |
735 | \fBif\fP \fIlist\fP; \fBthen\fP \fIlist;\fP \ |
736 | [ \fBelif\fP \fIlist\fP; \fBthen\fP \fIlist\fP; ] ... \ | |
737 | [ \fBelse\fP \fIlist\fP; ] \fBfi\fP | |
726f6388 JA |
738 | The |
739 | .B if | |
740 | .I list | |
741 | is executed. If its exit status is zero, the | |
742 | \fBthen\fP \fIlist\fP is executed. Otherwise, each \fBelif\fP | |
743 | \fIlist\fP is executed in turn, and if its exit status is zero, | |
744 | the corresponding \fBthen\fP \fIlist\fP is executed and the | |
745 | command completes. Otherwise, the \fBelse\fP \fIlist\fP is | |
746 | executed, if present. The exit status is the exit status of the | |
747 | last command executed, or zero if no condition tested true. | |
748 | .TP | |
749 | .PD 0 | |
ccc6cda3 | 750 | \fBwhile\fP \fIlist\fP; \fBdo\fP \fIlist\fP; \fBdone\fP |
726f6388 | 751 | .TP |
ccc6cda3 | 752 | \fBuntil\fP \fIlist\fP; \fBdo\fP \fIlist\fP; \fBdone\fP |
726f6388 JA |
753 | .PD |
754 | The \fBwhile\fP command continuously executes the \fBdo\fP | |
755 | \fIlist\fP as long as the last command in \fIlist\fP returns | |
756 | an exit status of zero. The \fBuntil\fP command is identical | |
757 | to the \fBwhile\fP command, except that the test is negated; | |
758 | the | |
759 | .B do | |
760 | .I list | |
761 | is executed as long as the last command in | |
762 | .I list | |
ccc6cda3 | 763 | returns a non-zero exit status. |
726f6388 JA |
764 | The exit status of the \fBwhile\fP and \fBuntil\fP commands |
765 | is the exit status | |
766 | of the last \fBdo\fP \fIlist\fP command executed, or zero if | |
767 | none was executed. | |
768 | .TP | |
769 | [ \fBfunction\fP ] \fIname\fP () { \fIlist\fP; } | |
770 | This defines a function named \fIname\fP. The \fIbody\fP of the | |
771 | function is the | |
772 | .I list | |
773 | of commands between { and }. This list | |
774 | is executed whenever \fIname\fP is specified as the | |
775 | name of a simple command. The exit status of a function is | |
776 | the exit status of the last command executed in the body. (See | |
777 | .SM | |
778 | .B FUNCTIONS | |
779 | below.) | |
780 | .SH COMMENTS | |
ccc6cda3 JA |
781 | In a non-interactive shell, or an interactive shell in which the |
782 | .B interactive_comments | |
783 | option to the | |
784 | .B shopt | |
785 | builtin is enabled (see | |
786 | .SM | |
787 | .B "SHELL BUILTIN COMMANDS" | |
788 | below), a word beginning with | |
726f6388 JA |
789 | .B # |
790 | causes that word and all remaining characters on that line to | |
791 | be ignored. An interactive shell without the | |
ccc6cda3 | 792 | .B interactive_comments |
ccc6cda3 JA |
793 | option enabled does not allow comments. The |
794 | .B interactive_comments | |
795 | option is on by default in interactive shells. | |
726f6388 JA |
796 | .SH QUOTING |
797 | \fIQuoting\fP is used to remove the special meaning of certain | |
798 | characters or words to the shell. Quoting can be used to | |
799 | disable special treatment for special characters, to prevent | |
800 | reserved words from being recognized as such, and to prevent | |
801 | parameter expansion. | |
802 | .PP | |
803 | Each of the \fImetacharacters\fP listed above under | |
804 | .SM | |
805 | .B DEFINITIONS | |
bb70624e JA |
806 | has special meaning to the shell and must be quoted if it is to |
807 | represent itself. | |
808 | .PP | |
809 | When the command history expansion facilities are being used, the | |
810 | \fIhistory expansion\fP character, usually \fB!\fP, must be quoted | |
811 | to prevent history expansion. | |
812 | .PP | |
813 | There are three quoting mechanisms: the | |
726f6388 JA |
814 | .IR "escape character" , |
815 | single quotes, and double quotes. | |
816 | .PP | |
817 | A non-quoted backslash (\fB\e\fP) is the | |
818 | .IR "escape character" . | |
819 | It preserves the literal value of the next character that follows, | |
820 | with the exception of <newline>. If a \fB\e\fP<newline> pair | |
cce855bc JA |
821 | appears, and the backslash is not itself quoted, the \fB\e\fP<newline> |
822 | is treated as a line continuation (that is, it is removed from the | |
823 | input stream and effectively ignored). | |
726f6388 JA |
824 | .PP |
825 | Enclosing characters in single quotes preserves the literal value | |
826 | of each character within the quotes. A single quote may not occur | |
827 | between single quotes, even when preceded by a backslash. | |
828 | .PP | |
829 | Enclosing characters in double quotes preserves the literal value | |
830 | of all characters within the quotes, with the exception of | |
831 | .BR $ , | |
832 | .BR ` , | |
833 | and | |
834 | .BR \e . | |
835 | The characters | |
836 | .B $ | |
837 | and | |
838 | .B ` | |
839 | retain their special meaning within double quotes. The backslash | |
840 | retains its special meaning only when followed by one of the following | |
841 | characters: | |
842 | .BR $ , | |
843 | .BR ` , | |
844 | \^\fB"\fP\^, | |
845 | .BR \e , | |
846 | or | |
847 | .BR <newline> . | |
848 | A double quote may be quoted within double quotes by preceding it with | |
849 | a backslash. | |
850 | .PP | |
851 | The special parameters | |
852 | .B * | |
853 | and | |
854 | .B @ | |
855 | have special meaning when in double | |
856 | quotes (see | |
857 | .SM | |
858 | .B PARAMETERS | |
859 | below). | |
ccc6cda3 JA |
860 | .PP |
861 | Words of the form \fB$\fP'\fIstring\fP' are treated specially. The | |
862 | word expands to \fIstring\fP, with backslash-escaped characters replaced | |
863 | as specifed by the ANSI C standard. Backslash escape sequences, if | |
864 | present, are decoded as follows: | |
865 | .RS | |
866 | .PD 0 | |
867 | .TP | |
868 | .B \ea | |
869 | alert (bell) | |
870 | .TP | |
871 | .B \eb | |
872 | backspace | |
873 | .TP | |
874 | .B \ee | |
875 | an escape character | |
876 | .TP | |
877 | .B \ef | |
878 | form feed | |
879 | .TP | |
880 | .B \en | |
881 | new line | |
882 | .TP | |
883 | .B \er | |
884 | carriage return | |
885 | .TP | |
886 | .B \et | |
887 | horizontal tab | |
888 | .TP | |
889 | .B \ev | |
890 | vertical tab | |
891 | .TP | |
892 | .B \e\e | |
893 | backslash | |
bb70624e JA |
894 | .TP |
895 | .B \e' | |
896 | single quote | |
ccc6cda3 JA |
897 | .TP |
898 | .B \e\fInnn\fP | |
cce855bc JA |
899 | the character whose ASCII code is the octal value \fInnn\fP |
900 | (one to three digits) | |
901 | .TP | |
902 | .B \ex\fInnn\fP | |
903 | the character whose ASCII code is the hexadecimal value \fInnn\fP | |
904 | (one to three digits) | |
ccc6cda3 JA |
905 | .PD |
906 | .RE | |
907 | .LP | |
bb70624e | 908 | The expanded result is single-quoted, as if the dollar sign had |
ccc6cda3 JA |
909 | not been present. |
910 | .PP | |
911 | A double-quoted string preceded by a dollar sign (\fB$\fP) will cause | |
912 | the string to be translated according to the current locale. | |
913 | If the current locale is \fBC\fP or \fBPOSIX\fP, the dollar sign | |
914 | is ignored. | |
915 | If the string is translated and replaced, the replacement is | |
916 | double-quoted. | |
726f6388 JA |
917 | .SH PARAMETERS |
918 | A | |
919 | .I parameter | |
ccc6cda3 JA |
920 | is an entity that stores values. |
921 | It can be a | |
726f6388 JA |
922 | .IR name , |
923 | a number, or one of the special characters listed below under | |
924 | .BR "Special Parameters" . | |
925 | For the shell's purposes, a | |
926 | .I variable | |
927 | is a parameter denoted by a | |
928 | .IR name . | |
929 | .PP | |
930 | A parameter is set if it has been assigned a value. The null string is | |
931 | a valid value. Once a variable is set, it may be unset only by using | |
932 | the | |
933 | .B unset | |
934 | builtin command (see | |
935 | .SM | |
936 | .B SHELL BUILTIN COMMANDS | |
937 | below). | |
938 | .PP | |
939 | A | |
940 | .I variable | |
941 | may be assigned to by a statement of the form | |
942 | .RS | |
943 | .PP | |
944 | \fIname\fP=[\fIvalue\fP] | |
945 | .RE | |
946 | .PP | |
947 | If | |
948 | .I value | |
949 | is not given, the variable is assigned the null string. All | |
950 | .I values | |
bb70624e JA |
951 | undergo tilde expansion, parameter and variable expansion, |
952 | command substitution, arithmetic expansion, and quote | |
ccc6cda3 JA |
953 | removal (see |
954 | .SM | |
955 | .B EXPANSION | |
956 | below). If the variable has its | |
cce855bc | 957 | .B integer |
726f6388 JA |
958 | attribute set (see |
959 | .B declare | |
960 | below in | |
961 | .SM | |
962 | .BR "SHELL BUILTIN COMMANDS" ) | |
963 | then | |
964 | .I value | |
cce855bc JA |
965 | is subject to arithmetic expansion even if the $((...)) expansion is |
966 | not used (see | |
ccc6cda3 JA |
967 | .B "Arithmetic Expansion" |
968 | below). | |
969 | Word splitting is not performed, with the exception | |
726f6388 JA |
970 | of \fB"$@"\fP as explained below under |
971 | .BR "Special Parameters" . | |
972 | Pathname expansion is not performed. | |
973 | .SS Positional Parameters | |
974 | .PP | |
975 | A | |
976 | .I positional parameter | |
977 | is a parameter denoted by one or more | |
978 | digits, other than the single digit 0. Positional parameters are | |
979 | assigned from the shell's arguments when it is invoked, | |
980 | and may be reassigned using the | |
981 | .B set | |
982 | builtin command. Positional parameters may not be assigned to | |
983 | with assignment statements. The positional parameters are | |
984 | temporarily replaced when a shell function is executed (see | |
985 | .SM | |
986 | .B FUNCTIONS | |
987 | below). | |
988 | .PP | |
989 | When a positional parameter consisting of more than a single | |
990 | digit is expanded, it must be enclosed in braces (see | |
991 | .SM | |
992 | .B EXPANSION | |
993 | below). | |
994 | .SS Special Parameters | |
995 | .PP | |
996 | The shell treats several parameters specially. These parameters may | |
997 | only be referenced; assignment to them is not allowed. | |
998 | .PD 0 | |
999 | .TP | |
1000 | .B * | |
1001 | Expands to the positional parameters, starting from one. When the | |
1002 | expansion occurs within double quotes, it expands to a single word | |
1003 | with the value of each parameter separated by the first character | |
1004 | of the | |
1005 | .SM | |
1006 | .B IFS | |
cce855bc JA |
1007 | special variable. That is, "\fB$*\fP" is equivalent |
1008 | to "\fB$1\fP\fIc\fP\fB$2\fP\fIc\fP\fB...\fP", where | |
726f6388 JA |
1009 | .I c |
1010 | is the first character of the value of the | |
1011 | .SM | |
1012 | .B IFS | |
1013 | variable. If | |
1014 | .SM | |
1015 | .B IFS | |
d166f048 JA |
1016 | is unset, the parameters are separated by spaces. |
1017 | If | |
1018 | .SM | |
1019 | .B IFS | |
1020 | is null, the parameters are joined without intervening separators. | |
726f6388 JA |
1021 | .TP |
1022 | .B @ | |
1023 | Expands to the positional parameters, starting from one. When the | |
cce855bc JA |
1024 | expansion occurs within double quotes, each parameter expands to a |
1025 | separate word. That is, "\fB$@\fP" is equivalent to | |
1026 | "\fB$1\fP" "\fB$2\fP" ... | |
1027 | When there are no positional parameters, "\fB$@\fP" and | |
726f6388 JA |
1028 | .B $@ |
1029 | expand to nothing (i.e., they are removed). | |
1030 | .TP | |
1031 | .B # | |
1032 | Expands to the number of positional parameters in decimal. | |
1033 | .TP | |
1034 | .B ? | |
1035 | Expands to the status of the most recently executed foreground | |
1036 | pipeline. | |
1037 | .TP | |
1038 | .B \- | |
1039 | Expands to the current option flags as specified upon invocation, | |
1040 | by the | |
1041 | .B set | |
1042 | builtin command, or those set by the shell itself | |
1043 | (such as the | |
1044 | .B \-i | |
cce855bc | 1045 | option). |
726f6388 JA |
1046 | .TP |
1047 | .B $ | |
1048 | Expands to the process ID of the shell. In a () subshell, it | |
1049 | expands to the process ID of the current shell, not the | |
1050 | subshell. | |
1051 | .TP | |
1052 | .B ! | |
1053 | Expands to the process ID of the most recently executed background | |
1054 | (asynchronous) command. | |
1055 | .TP | |
1056 | .B 0 | |
1057 | Expands to the name of the shell or shell script. This is set at | |
1058 | shell initialization. If | |
1059 | .B bash | |
1060 | is invoked with a file of commands, | |
1061 | .B $0 | |
1062 | is set to the name of that file. If | |
1063 | .B bash | |
1064 | is started with the | |
1065 | .B \-c | |
1066 | option, then | |
1067 | .B $0 | |
1068 | is set to the first argument after the string to be | |
1069 | executed, if one is present. Otherwise, it is set | |
ccc6cda3 | 1070 | to the file name used to invoke |
726f6388 JA |
1071 | .BR bash , |
1072 | as given by argument zero. | |
1073 | .TP | |
1074 | .B _ | |
ccc6cda3 JA |
1075 | At shell startup, set to the absolute file name of the shell or shell |
1076 | script being executed as passed in the argument list. | |
1077 | Subsequently, expands to the last argument to the previous command, | |
1078 | after expansion. | |
1079 | Also set to the full file name of each command executed and placed in | |
726f6388 | 1080 | the environment exported to that command. |
ccc6cda3 JA |
1081 | When checking mail, this parameter holds the name of the mail file |
1082 | currently being checked. | |
726f6388 JA |
1083 | .PD |
1084 | .SS Shell Variables | |
1085 | .PP | |
1086 | The following variables are set by the shell: | |
1087 | .PP | |
1088 | .PD 0 | |
1089 | .TP | |
1090 | .B PPID | |
cce855bc | 1091 | The process ID of the shell's parent. This variable is readonly. |
726f6388 JA |
1092 | .TP |
1093 | .B PWD | |
1094 | The current working directory as set by the | |
1095 | .B cd | |
1096 | command. | |
1097 | .TP | |
1098 | .B OLDPWD | |
1099 | The previous working directory as set by the | |
1100 | .B cd | |
1101 | command. | |
1102 | .TP | |
1103 | .B REPLY | |
1104 | Set to the line of input read by the | |
1105 | .B read | |
1106 | builtin command when no arguments are supplied. | |
1107 | .TP | |
1108 | .B UID | |
1109 | Expands to the user ID of the current user, initialized at shell startup. | |
cce855bc | 1110 | This variable is readonly. |
726f6388 JA |
1111 | .TP |
1112 | .B EUID | |
1113 | Expands to the effective user ID of the current user, initialized at | |
cce855bc | 1114 | shell startup. This variable is readonly. |
726f6388 | 1115 | .TP |
d166f048 JA |
1116 | .B GROUPS |
1117 | An array variable containing the list of groups of which the current | |
bb70624e JA |
1118 | user is a member. |
1119 | Assignments to | |
1120 | .SM | |
1121 | .B GROUPS | |
1122 | have no effect and are silently discarded. | |
1123 | If | |
1124 | .SM | |
1125 | .B GROUPS | |
1126 | is unset, it loses its special properties, even if it is | |
1127 | subsequently reset. | |
d166f048 | 1128 | .TP |
726f6388 | 1129 | .B BASH |
ccc6cda3 | 1130 | Expands to the full file name used to invoke this instance of |
726f6388 JA |
1131 | .BR bash . |
1132 | .TP | |
1133 | .B BASH_VERSION | |
ccc6cda3 | 1134 | Expands to a string describing the version of this instance of |
726f6388 JA |
1135 | .BR bash . |
1136 | .TP | |
ccc6cda3 | 1137 | .B BASH_VERSINFO |
cce855bc JA |
1138 | A readonly array variable whose members hold version information for |
1139 | this instance of | |
ccc6cda3 JA |
1140 | .BR bash . |
1141 | The values assigned to the array members are as follows: | |
1142 | .sp .5 | |
1143 | .RS | |
1144 | .PD 0 | |
1145 | .TP 24 | |
1146 | .B BASH_VERSINFO[\fR0\fP] | |
1147 | The major version number (the \fIrelease\fP). | |
1148 | .TP | |
1149 | .B BASH_VERSINFO[\fR1\fP] | |
1150 | The minor version number (the \fIversion\fP). | |
1151 | .TP | |
1152 | .B BASH_VERSINFO[\fR2\fP] | |
1153 | The patch level. | |
1154 | .TP | |
1155 | .B BASH_VERSINFO[\fR3\fP] | |
1156 | The build version. | |
1157 | .TP | |
1158 | .B BASH_VERSINFO[\fR4\fP] | |
1159 | The release status (e.g., \fIbeta1\fP). | |
1160 | .TP | |
1161 | .B BASH_VERSINFO[\fR5\fP] | |
1162 | The value of \fBMACHTYPE\fP. | |
1163 | .PD | |
1164 | .RE | |
1165 | .TP | |
726f6388 JA |
1166 | .B SHLVL |
1167 | Incremented by one each time an instance of | |
1168 | .B bash | |
1169 | is started. | |
1170 | .TP | |
1171 | .B RANDOM | |
ccc6cda3 JA |
1172 | Each time this parameter is referenced, a random integer between |
1173 | 0 and 32767 is | |
726f6388 JA |
1174 | generated. The sequence of random numbers may be initialized by assigning |
1175 | a value to | |
1176 | .SM | |
1177 | .BR RANDOM . | |
1178 | If | |
1179 | .SM | |
1180 | .B RANDOM | |
1181 | is unset, it loses its special properties, even if it is | |
1182 | subsequently reset. | |
1183 | .TP | |
1184 | .B SECONDS | |
1185 | Each time this parameter is | |
1186 | referenced, the number of seconds since shell invocation is returned. If a | |
1187 | value is assigned to | |
1188 | .SM | |
1189 | .BR SECONDS , | |
1190 | the value returned upon subsequent | |
1191 | references is | |
1192 | the number of seconds since the assignment plus the value assigned. | |
1193 | If | |
1194 | .SM | |
1195 | .B SECONDS | |
1196 | is unset, it loses its special properties, even if it is | |
1197 | subsequently reset. | |
1198 | .TP | |
1199 | .B LINENO | |
1200 | Each time this parameter is referenced, the shell substitutes | |
1201 | a decimal number representing the current sequential line number | |
1202 | (starting with 1) within a script or function. When not in a | |
1203 | script or function, the value substituted is not guaranteed to | |
ccc6cda3 | 1204 | be meaningful. |
726f6388 JA |
1205 | If |
1206 | .SM | |
1207 | .B LINENO | |
1208 | is unset, it loses its special properties, even if it is | |
1209 | subsequently reset. | |
1210 | .TP | |
1211 | .B HISTCMD | |
1212 | The history number, or index in the history list, of the current | |
ccc6cda3 JA |
1213 | command. |
1214 | If | |
726f6388 JA |
1215 | .SM |
1216 | .B HISTCMD | |
1217 | is unset, it loses its special properties, even if it is | |
1218 | subsequently reset. | |
1219 | .TP | |
bb70624e JA |
1220 | .B FUNCNAME |
1221 | The name of any currently-executing shell function. | |
1222 | This variable exists only when a shell function is executing. | |
1223 | Assignments to | |
1224 | .SM | |
1225 | .B FUNCNAME | |
1226 | have no effect and are silently discarded. | |
1227 | If | |
1228 | .SM | |
1229 | .B FUNCNAME | |
1230 | is unset, it loses its special properties, even if it is | |
1231 | subsequently reset. | |
1232 | .TP | |
ccc6cda3 JA |
1233 | .B DIRSTACK |
1234 | An array variable (see | |
1235 | .B Arrays | |
1236 | below) containing the current contents of the directory stack. | |
1237 | Directories appear in the stack in the order they are displayed by the | |
1238 | .B dirs | |
1239 | builtin. | |
1240 | Assigning to members of this array variable may be used to modify | |
1241 | directories already in the stack, but the | |
1242 | .B pushd | |
1243 | and | |
1244 | .B popd | |
1245 | builtins must be used to add and remove directories. | |
1246 | Assignment to this variable will not change the current directory. | |
1247 | If | |
1248 | .SM | |
1249 | .B DIRSTACK | |
1250 | is unset, it loses its special properties, even if it is | |
1251 | subsequently reset. | |
1252 | .TP | |
1253 | .B PIPESTATUS | |
1254 | An array variable (see | |
1255 | .B Arrays | |
1256 | below) containing a list of exit status values from the processes | |
1257 | in the most-recently-executed foreground pipeline (which may | |
1258 | contain only a single command). | |
1259 | .TP | |
726f6388 JA |
1260 | .B OPTARG |
1261 | The value of the last option argument processed by the | |
1262 | .B getopts | |
1263 | builtin command (see | |
1264 | .SM | |
1265 | .B SHELL BUILTIN COMMANDS | |
1266 | below). | |
1267 | .TP | |
1268 | .B OPTIND | |
1269 | The index of the next argument to be processed by the | |
1270 | .B getopts | |
1271 | builtin command (see | |
1272 | .SM | |
1273 | .B SHELL BUILTIN COMMANDS | |
1274 | below). | |
1275 | .TP | |
ccc6cda3 JA |
1276 | .B HOSTNAME |
1277 | Automatically set to the name of the current host. | |
1278 | .TP | |
726f6388 JA |
1279 | .B HOSTTYPE |
1280 | Automatically set to a string that uniquely | |
1281 | describes the type of machine on which | |
1282 | .B bash | |
ccc6cda3 JA |
1283 | is executing. |
1284 | The default is system-dependent. | |
726f6388 JA |
1285 | .TP |
1286 | .B OSTYPE | |
1287 | Automatically set to a string that | |
1288 | describes the operating system on which | |
1289 | .B bash | |
ccc6cda3 JA |
1290 | is executing. |
1291 | The default is system-dependent. | |
1292 | .TP | |
1293 | .B MACHTYPE | |
1294 | Automatically set to a string that fully describes the system | |
1295 | type on which | |
1296 | .B bash | |
1297 | is executing, in the standard GNU \fIcpu-company-system\fP format. | |
1298 | The default is system-dependent. | |
1299 | .TP | |
1300 | .B SHELLOPTS | |
1301 | A colon-separated list of enabled shell options. Each word in | |
1302 | the list is a valid argument for the | |
1303 | .B \-o | |
1304 | option to the | |
1305 | .B set | |
1306 | builtin command (see | |
1307 | .SM | |
1308 | .B "SHELL BUILTIN COMMANDS" | |
1309 | below). The options appearing in | |
1310 | .SM | |
1311 | .B SHELLOPTS | |
1312 | are those reported as | |
1313 | .I on | |
1314 | by \fBset \-o\fP. | |
1315 | If this variable is in the environment when | |
1316 | .B bash | |
1317 | starts up, each shell option in the list will be enabled before | |
1318 | reading any startup files. | |
1319 | This variable is read-only. | |
bb70624e JA |
1320 | .TP |
1321 | .B COMP_WORDS | |
1322 | An array variable (see \fBArrays\fP below) consisting of the individual | |
1323 | words in the current command line. | |
1324 | This variable is available only in shell functions invoked by the | |
1325 | programmable completion facilities (see \fBProgrammable Completion\fP | |
1326 | below). | |
1327 | .TP | |
1328 | .B COMP_CWORD | |
1329 | An index into \fB${COMP_WORDS}\fP of the word containing the current | |
1330 | cursor position. | |
1331 | This variable is available only in shell functions invoked by the | |
1332 | programmable completion facilities (see \fBProgrammable Completion\fP | |
1333 | below). | |
1334 | .TP | |
1335 | .B COMP_LINE | |
1336 | The current command line. | |
1337 | This variable is available only in shell functions and external | |
1338 | commands invoked by the | |
1339 | programmable completion facilities (see \fBProgrammable Completion\fP | |
1340 | below). | |
1341 | .TP | |
1342 | .B COMP_POINT | |
1343 | The index of the current cursor position relative to the beginning of | |
1344 | the current command. | |
1345 | If the current cursor position is at the end of the current command, | |
1346 | the value of this variable is equal to \fB${#COMP_LINE}\fP. | |
1347 | This variable is available only in shell functions and external | |
1348 | commands invoked by the | |
1349 | programmable completion facilities (see \fBProgrammable Completion\fP | |
1350 | below). | |
726f6388 JA |
1351 | .PD |
1352 | .PP | |
1353 | The following variables are used by the shell. In some cases, | |
1354 | .B bash | |
1355 | assigns a default value to a variable; these cases are noted | |
1356 | below. | |
1357 | .PP | |
1358 | .PD 0 | |
1359 | .TP | |
1360 | .B IFS | |
1361 | The | |
1362 | .I Internal Field Separator | |
1363 | that is used | |
1364 | for word splitting after expansion and to | |
1365 | split lines into words with the | |
1366 | .B read | |
1367 | builtin command. The default value is | |
1368 | ``<space><tab><newline>''. | |
1369 | .TP | |
1370 | .B PATH | |
1371 | The search path for commands. It | |
1372 | is a colon-separated list of directories in which | |
1373 | the shell looks for commands (see | |
1374 | .SM | |
1375 | .B COMMAND EXECUTION | |
ccc6cda3 | 1376 | below). The default path is system-dependent, |
726f6388 JA |
1377 | and is set by the administrator who installs |
1378 | .BR bash . | |
1379 | A common value is ``/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin:.''. | |
1380 | .TP | |
1381 | .B HOME | |
1382 | The home directory of the current user; the default argument for the | |
1383 | \fBcd\fP builtin command. | |
cce855bc | 1384 | The value of this variable is also used when performing tilde expansion. |
726f6388 JA |
1385 | .TP |
1386 | .B CDPATH | |
1387 | The search path for the | |
1388 | .B cd | |
cce855bc JA |
1389 | command. |
1390 | This is a colon-separated list of directories in which the shell looks | |
1391 | for destination directories specified by the | |
726f6388 | 1392 | .B cd |
cce855bc JA |
1393 | command. |
1394 | A sample value is ``.:~:/usr''. | |
726f6388 | 1395 | .TP |
d166f048 | 1396 | .B BASH_ENV |
726f6388 JA |
1397 | If this parameter is set when \fBbash\fP is executing a shell script, |
1398 | its value is interpreted as a filename containing commands to | |
1399 | initialize the shell, as in | |
cce855bc | 1400 | .IR ~/.bashrc . |
726f6388 JA |
1401 | The value of |
1402 | .SM | |
d166f048 | 1403 | .B BASH_ENV |
726f6388 | 1404 | is subjected to parameter expansion, command substitution, and arithmetic |
ccc6cda3 | 1405 | expansion before being interpreted as a file name. |
726f6388 JA |
1406 | .SM |
1407 | .B PATH | |
ccc6cda3 | 1408 | is not used to search for the resultant file name. |
726f6388 JA |
1409 | .TP |
1410 | .B MAIL | |
ccc6cda3 | 1411 | If this parameter is set to a file name and the |
726f6388 JA |
1412 | .SM |
1413 | .B MAILPATH | |
1414 | variable is not set, | |
1415 | .B bash | |
1416 | informs the user of the arrival of mail in the specified file. | |
1417 | .TP | |
1418 | .B MAILCHECK | |
1419 | Specifies how | |
1420 | often (in seconds) | |
1421 | .B bash | |
1422 | checks for mail. The default is 60 seconds. When it is time to check | |
ccc6cda3 | 1423 | for mail, the shell does so before displaying the primary prompt. |
726f6388 JA |
1424 | If this variable is unset, the shell disables mail checking. |
1425 | .TP | |
1426 | .B MAILPATH | |
ccc6cda3 | 1427 | A colon-separated list of file names to be checked for mail. |
cce855bc JA |
1428 | The message to be printed when mail arrives in a particular file |
1429 | may be specified by separating the file name from the message with a `?'. | |
1430 | When used in the text of the message, \fB$_\fP expands to the name of | |
1431 | the current mailfile. | |
726f6388 JA |
1432 | Example: |
1433 | .RS | |
1434 | .PP | |
bb70624e | 1435 | \fBMAILPATH\fP='/var/mail/bfox?"You have mail":~/shell\-mail?"$_ has mail!"' |
726f6388 JA |
1436 | .PP |
1437 | .B Bash | |
1438 | supplies a default value for this variable, but the location of the user | |
bb70624e | 1439 | mail files that it uses is system dependent (e.g., /var/mail/\fB$USER\fP). |
726f6388 JA |
1440 | .RE |
1441 | .TP | |
726f6388 JA |
1442 | .B PS1 |
1443 | The value of this parameter is expanded (see | |
1444 | .SM | |
1445 | .B PROMPTING | |
1446 | below) and used as the primary prompt string. The default value is | |
ccc6cda3 | 1447 | ``\fB\es\-\ev\e$ \fP''. |
726f6388 JA |
1448 | .TP |
1449 | .B PS2 | |
ccc6cda3 JA |
1450 | The value of this parameter is expanded as with |
1451 | .B PS1 | |
726f6388 JA |
1452 | and used as the secondary prompt string. The default is |
1453 | ``\fB> \fP''. | |
1454 | .TP | |
1455 | .B PS3 | |
1456 | The value of this parameter is used as the prompt for the | |
ccc6cda3 | 1457 | .B select |
726f6388 JA |
1458 | command (see |
1459 | .SM | |
1460 | .B SHELL GRAMMAR | |
1461 | above). | |
1462 | .TP | |
1463 | .B PS4 | |
ccc6cda3 JA |
1464 | The value of this parameter is expanded as with |
1465 | .B PS1 | |
726f6388 JA |
1466 | and the value is printed before each command |
1467 | .B bash | |
1468 | displays during an execution trace. The first character of | |
1469 | .SM | |
1470 | .B PS4 | |
1471 | is replicated multiple times, as necessary, to indicate multiple | |
1472 | levels of indirection. The default is ``\fB+ \fP''. | |
1473 | .TP | |
ccc6cda3 JA |
1474 | .B TIMEFORMAT |
1475 | The value of this parameter is used as a format string specifying | |
1476 | how the timing information for pipelines prefixed with the | |
1477 | .B time | |
1478 | reserved word should be displayed. | |
1479 | The \fB%\fP character introduces an escape sequence that is | |
1480 | expanded to a time value or other information. | |
1481 | The escape sequences and their meanings are as follows; the | |
1482 | braces denote optional portions. | |
1483 | .sp .5 | |
1484 | .RS | |
1485 | .PD 0 | |
1486 | .TP 10 | |
1487 | .B %% | |
1488 | A literal \fB%\fP. | |
1489 | .TP | |
1490 | .B %[\fIp\fP][l]R | |
1491 | The elapsed time in seconds. | |
1492 | .TP | |
1493 | .B %[\fIp\fP][l]U | |
1494 | The number of CPU seconds spent in user mode. | |
1495 | .TP | |
1496 | .B %[\fIp\fP][l]S | |
1497 | The number of CPU seconds spent in system mode. | |
1498 | .TP | |
1499 | .B %P | |
1500 | The CPU percentage, computed as (%U + %S) / %R. | |
1501 | .PD | |
1502 | .RE | |
1503 | .IP | |
1504 | The optional \fIp\fP is a digit specifying the \fIprecision\fP, | |
1505 | the number of fractional digits after a decimal point. | |
1506 | A value of 0 causes no decimal point or fraction to be output. | |
1507 | At most three places after the decimal point may be specified; | |
1508 | values of \fIp\fP greater than 3 are changed to 3. | |
1509 | If \fIp\fP is not specified, the value 3 is used. | |
1510 | .IP | |
1511 | The optional \fBl\fP specifies a longer format, including | |
1512 | minutes, of the form \fIMM\fPm\fISS\fP.\fIFF\fPs. | |
1513 | The value of \fIp\fP determines whether or not the fraction is | |
1514 | included. | |
1515 | .IP | |
1516 | If this variable is not set, \fBbash\fP acts as if it had the | |
1517 | value \fB$'\enreal\et%3lR\enuser\et%3lU\ensys\t%3lS'\fP. | |
1518 | If the value is null, no timing information is displayed. | |
1519 | A trailing newline is added when the format string is displayed. | |
1520 | .TP | |
726f6388 JA |
1521 | .B HISTSIZE |
1522 | The number of commands to remember in the command history (see | |
1523 | .SM | |
1524 | .B HISTORY | |
1525 | below). The default value is 500. | |
1526 | .TP | |
1527 | .B HISTFILE | |
ccc6cda3 | 1528 | The name of the file in which command history is saved (see |
726f6388 JA |
1529 | .SM |
1530 | .B HISTORY | |
ccc6cda3 | 1531 | below). The default value is \fI~/.bash_history\fP. If unset, the |
726f6388 JA |
1532 | command history is not saved when an interactive shell exits. |
1533 | .TP | |
1534 | .B HISTFILESIZE | |
1535 | The maximum number of lines contained in the history file. When this | |
1536 | variable is assigned a value, the history file is truncated, if | |
1537 | necessary, to contain no more than that number of lines. The default | |
ccc6cda3 JA |
1538 | value is 500. The history file is also truncated to this size after |
1539 | writing it when an interactive shell exits. | |
726f6388 JA |
1540 | .TP |
1541 | .B OPTERR | |
1542 | If set to the value 1, | |
1543 | .B bash | |
1544 | displays error messages generated by the | |
1545 | .B getopts | |
1546 | builtin command (see | |
1547 | .SM | |
1548 | .B SHELL BUILTIN COMMANDS | |
1549 | below). | |
1550 | .SM | |
1551 | .B OPTERR | |
1552 | is initialized to 1 each time the shell is invoked or a shell | |
1553 | script is executed. | |
1554 | .TP | |
ccc6cda3 JA |
1555 | .B LANG |
1556 | Used to determine the locale category for any category not specifically | |
1557 | selected with a variable starting with \fBLC_\fP. | |
1558 | .TP | |
1559 | .B LC_ALL | |
1560 | This variable overrides the value of \fBLANG\fP and any other | |
1561 | \fBLC_\fP variable specifying a locale category. | |
1562 | .TP | |
1563 | .B LC_COLLATE | |
1564 | This variable determines the collation order used when sorting the | |
cce855bc JA |
1565 | results of pathname expansion, and determines the behavior of range |
1566 | expressions, equivalence classes, and collating sequences within | |
1567 | pathname expansion and pattern matching. | |
1568 | .TP | |
1569 | .B LC_CTYPE | |
1570 | This variable determines the interpretation of characters and the | |
1571 | behavior of character classes within pathname expansion and pattern | |
1572 | matching. | |
ccc6cda3 JA |
1573 | .TP |
1574 | .B LC_MESSAGES | |
1575 | This variable determines the locale used to translate double-quoted | |
1576 | strings preceded by a \fB$\fP. | |
1577 | .TP | |
bb70624e JA |
1578 | .B LC_NUMERIC |
1579 | This variable determines the locale category used for number formatting. | |
1580 | .TP | |
726f6388 JA |
1581 | .B PROMPT_COMMAND |
1582 | If set, the value is executed as a command prior to issuing each primary | |
1583 | prompt. | |
1584 | .TP | |
1585 | .B IGNOREEOF | |
1586 | Controls the | |
ccc6cda3 | 1587 | action of an interactive shell on receipt of an |
726f6388 JA |
1588 | .SM |
1589 | .B EOF | |
1590 | character as the sole input. If set, the value is the number of | |
1591 | consecutive | |
1592 | .SM | |
1593 | .B EOF | |
ccc6cda3 JA |
1594 | characters which must be |
1595 | typed as the first characters on an input line before | |
726f6388 JA |
1596 | .B bash |
1597 | exits. If the variable exists but does not have a numeric value, or | |
1598 | has no value, the default value is 10. If it does not exist, | |
1599 | .SM | |
1600 | .B EOF | |
ccc6cda3 | 1601 | signifies the end of input to the shell. |
726f6388 JA |
1602 | .TP |
1603 | .B TMOUT | |
1604 | If set to a value greater than zero, the value is interpreted as the | |
1605 | number of seconds to wait for input after issuing the primary prompt. | |
1606 | .B Bash | |
1607 | terminates after waiting for that number of seconds if input does | |
1608 | not arrive. | |
1609 | .TP | |
1610 | .B FCEDIT | |
1611 | The default editor for the | |
1612 | .B fc | |
1613 | builtin command. | |
1614 | .TP | |
1615 | .B FIGNORE | |
1616 | A colon-separated list of suffixes to ignore when performing | |
1617 | filename completion (see | |
1618 | .SM | |
1619 | .B READLINE | |
ccc6cda3 JA |
1620 | below). |
1621 | A filename whose suffix matches one of the entries in | |
726f6388 JA |
1622 | .SM |
1623 | .B FIGNORE | |
ccc6cda3 JA |
1624 | is excluded from the list of matched filenames. |
1625 | A sample value is ``.o:~''. | |
1626 | .TP | |
1627 | .B GLOBIGNORE | |
1628 | A colon-separated list of patterns defining the set of filenames to | |
1629 | be ignored by pathname expansion. | |
1630 | If a filename matched by a pathname expansion pattern also matches one | |
1631 | of the patterns in | |
1632 | .SM | |
1633 | .BR GLOBIGNORE , | |
1634 | it is removed from the list of matches. | |
726f6388 JA |
1635 | .TP |
1636 | .B INPUTRC | |
ccc6cda3 JA |
1637 | The filename for the |
1638 | .B readline | |
1639 | startup file, overriding the default of | |
726f6388 JA |
1640 | .FN ~/.inputrc |
1641 | (see | |
1642 | .SM | |
1643 | .B READLINE | |
1644 | below). | |
1645 | .TP | |
726f6388 | 1646 | .B HISTCONTROL |
726f6388 JA |
1647 | If set to a value of |
1648 | .IR ignorespace , | |
1649 | lines which begin with a | |
1650 | .B space | |
bb70624e JA |
1651 | character are not entered on the history list. |
1652 | If set to a value of | |
726f6388 JA |
1653 | .IR ignoredups , |
1654 | lines matching the last history line are not entered. | |
1655 | A value of | |
1656 | .I ignoreboth | |
1657 | combines the two options. | |
1658 | If unset, or if set to any other value than those above, | |
1659 | all lines read | |
ccc6cda3 JA |
1660 | by the parser are saved on the history list, subject to the value |
1661 | of | |
1662 | .BR HISTIGNORE . | |
1663 | This variable's function is superseded by | |
1664 | .BR HISTIGNORE . | |
cce855bc JA |
1665 | The second and subsequent lines of a multi-line compound command are |
1666 | not tested, and are added to the history regardless of the value of | |
1667 | .BR HISTCONTROL . | |
ccc6cda3 JA |
1668 | .TP |
1669 | .B HISTIGNORE | |
1670 | A colon-separated list of patterns used to decide which command lines | |
1671 | should be saved on the history list. Each pattern is anchored at the | |
bb70624e | 1672 | beginning of the line and must match the complete line (no implicit |
ccc6cda3 JA |
1673 | `\fB*\fP' is appended). Each pattern is tested against the line |
1674 | after the checks specified by | |
1675 | .B HISTCONTROL | |
1676 | are applied. | |
1677 | In addition to the normal shell pattern matching characters, `\fB&\fP' | |
1678 | matches the previous history line. `\fB&\fP' may be escaped using a | |
bb70624e | 1679 | backslash; the backslash is removed before attempting a match. |
cce855bc JA |
1680 | The second and subsequent lines of a multi-line compound command are |
1681 | not tested, and are added to the history regardless of the value of | |
1682 | .BR HISTIGNORE . | |
726f6388 JA |
1683 | .TP |
1684 | .B histchars | |
1685 | The two or three characters which control history expansion | |
1686 | and tokenization (see | |
1687 | .SM | |
1688 | .B HISTORY EXPANSION | |
bb70624e | 1689 | below). The first character is the \fIhistory expansion\fP character, |
cce855bc | 1690 | the character which signals the start of a history |
726f6388 | 1691 | expansion, normally `\fB!\fP'. |
bb70624e | 1692 | The second character is the \fIquick substitution\fP |
726f6388 JA |
1693 | character, which is used as shorthand for re-running the previous |
1694 | command entered, substituting one string for another in the command. | |
1695 | The default is `\fB^\fP'. | |
1696 | The optional third character is the character | |
cce855bc | 1697 | which indicates that the remainder of the line is a comment when found |
726f6388 JA |
1698 | as the first character of a word, normally `\fB#\fP'. The history |
1699 | comment character causes history substitution to be skipped for the | |
1700 | remaining words on the line. It does not necessarily cause the shell | |
1701 | parser to treat the rest of the line as a comment. | |
1702 | .TP | |
726f6388 | 1703 | .B HOSTFILE |
726f6388 JA |
1704 | Contains the name of a file in the same format as |
1705 | .FN /etc/hosts | |
1706 | that should be read when the shell needs to complete a | |
bb70624e JA |
1707 | hostname. |
1708 | The list of possible hostname completions may be changed while the | |
1709 | shell is running; | |
1710 | the next time hostname completion is attempted after the | |
1711 | value is changed, | |
726f6388 | 1712 | .B bash |
bb70624e JA |
1713 | adds the contents of the new file to the existing list. |
1714 | If | |
1715 | .SM | |
1716 | .B HOSTFILE | |
1717 | is set, but has no value, \fBbash\fP attempts to read | |
1718 | .FN /etc/hosts | |
1719 | to obtain the list of possible hostname completions. | |
1720 | When | |
1721 | .SM | |
1722 | .B HOSTFILE | |
1723 | is unset, the hostname list is cleared. | |
726f6388 | 1724 | .TP |
726f6388 JA |
1725 | .B auto_resume |
1726 | This variable controls how the shell interacts with the user and | |
1727 | job control. If this variable is set, single word simple | |
1728 | commands without redirections are treated as candidates for resumption | |
1729 | of an existing stopped job. There is no ambiguity allowed; if there is | |
1730 | more than one job beginning with the string typed, the job most recently | |
1731 | accessed is selected. The | |
1732 | .I name | |
1733 | of a stopped job, in this context, is the command line used to | |
1734 | start it. | |
1735 | If set to the value | |
1736 | .IR exact , | |
1737 | the string supplied must match the name of a stopped job exactly; | |
1738 | if set to | |
1739 | .IR substring , | |
1740 | the string supplied needs to match a substring of the name of a | |
1741 | stopped job. The | |
1742 | .I substring | |
1743 | value provides functionality analogous to the | |
1744 | .B %? | |
ccc6cda3 | 1745 | job identifier (see |
726f6388 JA |
1746 | .SM |
1747 | .B JOB CONTROL | |
1748 | below). If set to any other value, the supplied string must | |
1749 | be a prefix of a stopped job's name; this provides functionality | |
1750 | analogous to the | |
1751 | .B % | |
ccc6cda3 | 1752 | job identifier. |
bb70624e JA |
1753 | .TP |
1754 | .B COMPREPLY | |
1755 | An array variable from which \fBbash\fP reads the possible completions | |
1756 | generated by a shell function invoked by the programmable completion | |
1757 | facility (see \fBProgrammable Completion\fP below). | |
726f6388 | 1758 | .PD |
ccc6cda3 JA |
1759 | .SS Arrays |
1760 | .B Bash | |
1761 | provides one-dimensional array variables. Any variable may be used as | |
1762 | an array; the | |
1763 | .B declare | |
1764 | builtin will explicitly declare an array. There is no maximum | |
1765 | limit on the size of an array, nor any requirement that members | |
1766 | be indexed or assigned contiguously. Arrays are indexed using | |
1767 | integers and are zero-based. | |
1768 | .PP | |
1769 | An array is created automatically if any variable is assigned to using | |
1770 | the syntax \fIname\fP[\fIsubscript\fP]=\fIvalue\fP. The | |
1771 | .I subscript | |
1772 | is treated as an arithmetic expression that must evaluate to a number | |
1773 | greater than or equal to zero. To explicitly declare an array, use | |
1774 | .B declare \-a \fIname\fP | |
1775 | (see | |
1776 | .SM | |
1777 | .B SHELL BUILTIN COMMANDS | |
1778 | below). | |
1779 | .B declare \-a \fIname\fP[\fIsubscript\fP] | |
1780 | is also accepted; the \fIsubscript\fP is ignored. Attributes may be | |
1781 | specified for an array variable using the | |
1782 | .B declare | |
1783 | and | |
1784 | .B readonly | |
1785 | builtins. Each attribute applies to all members of an array. | |
1786 | .PP | |
1787 | Arrays are assigned to using compound assignments of the form | |
1788 | \fIname\fP=\fB(\fPvalue\fI1\fP ... value\fIn\fP\fB)\fP, where each | |
1789 | \fIvalue\fP is of the form [\fIsubscript\fP]=\fIstring\fP. Only | |
1790 | \fIstring\fP is required. If | |
1791 | the optional brackets and subscript are supplied, that index is assigned to; | |
1792 | otherwise the index of the element assigned is the last index assigned | |
1793 | to by the statement plus one. Indexing starts at zero. | |
1794 | This syntax is also accepted by the | |
1795 | .B declare | |
1796 | builtin. Individual array elements may be assigned to using the | |
1797 | \fIname\fP[\fIsubscript\fP]=\fIvalue\fP syntax introduced above. | |
1798 | .PP | |
1799 | Any element of an array may be referenced using | |
1800 | ${\fIname\fP[\fIsubscript\fP]}. The braces are required to avoid | |
1801 | conflicts with pathname expansion. If | |
1802 | \fIsubscript\fP is \fB@\fP or \fB*\fP, the word expands to | |
1803 | all members of \fIname\fP. These subscripts differ only when the | |
1804 | word appears within double quotes. If the word is double-quoted, | |
1805 | ${\fIname\fP[*]} expands to a single | |
1806 | word with the value of each array member separated by the first | |
1807 | character of the | |
1808 | .SM | |
1809 | .B IFS | |
1810 | special variable, and ${\fIname\fP[@]} expands each element of | |
1811 | \fIname\fP to a separate word. When there are no array members, | |
1812 | ${\fIname\fP[@]} expands to nothing. This is analogous to the expansion | |
1813 | of the special parameters \fB*\fP and \fB@\fP (see | |
1814 | .B Special Parameters | |
1815 | above). ${#\fIname\fP[\fIsubscript\fP]} expands to the length of | |
1816 | ${\fIname\fP[\fIsubscript\fP]}. If \fIsubscript\fP is \fB*\fP or | |
1817 | \fB@\fP, the expansion is the number of elements in the array. | |
1818 | Referencing an array variable without a subscript is equivalent to | |
1819 | referencing element zero. | |
1820 | .PP | |
1821 | The | |
1822 | .B unset | |
bb70624e | 1823 | builtin is used to destroy arrays. \fBunset\fP \fIname\fP[\fIsubscript\fP] |
ccc6cda3 JA |
1824 | destroys the array element at index \fIsubscript\fP. |
1825 | \fBunset\fP \fIname\fP, where \fIname\fP is an array, or | |
1826 | \fBunset\fP \fIname\fP[\fIsubscript\fP], where | |
1827 | \fIsubscript\fP is \fB*\fP or \fB@\fP, removes the entire array. | |
1828 | .PP | |
1829 | The | |
1830 | .BR declare , | |
1831 | .BR local , | |
1832 | and | |
1833 | .B readonly | |
1834 | builtins each accept a | |
1835 | .B \-a | |
1836 | option to specify an array. The | |
1837 | .B read | |
1838 | builtin accepts a | |
1839 | .B \-a | |
1840 | option to assign a list of words read from the standard input | |
1841 | to an array. The | |
1842 | .B set | |
1843 | and | |
1844 | .B declare | |
1845 | builtins display array values in a way that allows them to be | |
1846 | reused as assignments. | |
726f6388 JA |
1847 | .SH EXPANSION |
1848 | Expansion is performed on the command line after it has been split into | |
1849 | words. There are seven kinds of expansion performed: | |
1850 | .IR "brace expansion" , | |
1851 | .IR "tilde expansion" , | |
1852 | .IR "parameter and variable expansion" , | |
1853 | .IR "command substitution" , | |
1854 | .IR "arithmetic expansion" , | |
1855 | .IR "word splitting" , | |
1856 | and | |
1857 | .IR "pathname expansion" . | |
1858 | .PP | |
1859 | The order of expansions is: brace expansion, tilde expansion, | |
ccc6cda3 JA |
1860 | parameter, variable and arithmetic expansion and |
1861 | command substitution | |
1862 | (done in a left-to-right fashion), word splitting, and pathname | |
726f6388 JA |
1863 | expansion. |
1864 | .PP | |
1865 | On systems that can support it, there is an additional expansion | |
1866 | available: \fIprocess substitution\fP. | |
1867 | .PP | |
1868 | Only brace expansion, word splitting, and pathname expansion | |
1869 | can change the number of words of the expansion; other expansions | |
1870 | expand a single word to a single word. | |
ccc6cda3 | 1871 | The only exceptions to this are the expansions of |
cce855bc | 1872 | "\fB$@\fP" and "\fB${\fP\fIname\fP\fB[@]}\fP" |
ccc6cda3 | 1873 | as explained above (see |
726f6388 JA |
1874 | .SM |
1875 | .BR PARAMETERS ). | |
1876 | .SS Brace Expansion | |
1877 | .PP | |
1878 | .I "Brace expansion" | |
1879 | is a mechanism by which arbitrary strings | |
1880 | may be generated. This mechanism is similar to | |
1881 | \fIpathname expansion\fP, but the filenames generated | |
1882 | need not exist. Patterns to be brace expanded take | |
1883 | the form of an optional | |
1884 | .IR preamble , | |
1885 | followed by a series of comma-separated strings | |
1886 | between a pair of braces, followed by an optional | |
cce855bc | 1887 | .IR postscript . |
ccc6cda3 | 1888 | The preamble is prefixed to each string contained |
cce855bc | 1889 | within the braces, and the postscript is then appended |
726f6388 JA |
1890 | to each resulting string, expanding left to right. |
1891 | .PP | |
1892 | Brace expansions may be nested. The results of each expanded | |
1893 | string are not sorted; left to right order is preserved. | |
1894 | For example, a\fB{\fPd,c,b\fB}\fPe expands into `ade ace abe'. | |
1895 | .PP | |
1896 | Brace expansion is performed before any other expansions, | |
1897 | and any characters special to other expansions are preserved | |
1898 | in the result. It is strictly textual. | |
1899 | .B Bash | |
1900 | does not apply any syntactic interpretation to the context of the | |
1901 | expansion or the text between the braces. | |
1902 | .PP | |
1903 | A correctly-formed brace expansion must contain unquoted opening | |
1904 | and closing braces, and at least one unquoted comma. | |
1905 | Any incorrectly formed brace expansion is left unchanged. | |
ccc6cda3 JA |
1906 | A \fB{\fP or \fB,\fP may be quoted with a backslash to prevent its |
1907 | being considered part of a brace expression. | |
bb70624e JA |
1908 | To avoid conflicts with parameter expansion, the string \fB${\fP |
1909 | is not considered eligible for brace expansion. | |
726f6388 JA |
1910 | .PP |
1911 | This construct is typically used as shorthand when the common | |
1912 | prefix of the strings to be generated is longer than in the | |
1913 | above example: | |
1914 | .RS | |
1915 | .PP | |
1916 | mkdir /usr/local/src/bash/{old,new,dist,bugs} | |
1917 | .RE | |
1918 | or | |
1919 | .RS | |
1920 | chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}} | |
1921 | .RE | |
1922 | .PP | |
1923 | Brace expansion introduces a slight incompatibility with | |
ccc6cda3 JA |
1924 | historical versions of |
1925 | .BR sh . | |
726f6388 JA |
1926 | .B sh |
1927 | does not treat opening or closing braces specially when they | |
1928 | appear as part of a word, and preserves them in the output. | |
1929 | .B Bash | |
1930 | removes braces from words as a consequence of brace | |
1931 | expansion. For example, a word entered to | |
1932 | .B sh | |
1933 | as \fIfile{1,2}\fP | |
1934 | appears identically in the output. The same word is | |
1935 | output as | |
1936 | .I file1 file2 | |
1937 | after expansion by | |
1938 | .BR bash . | |
1939 | If strict compatibility with | |
1940 | .B sh | |
1941 | is desired, start | |
1942 | .B bash | |
1943 | with the | |
ccc6cda3 JA |
1944 | .B +B |
1945 | option or disable brace expansion with the | |
1946 | .B +B | |
726f6388 JA |
1947 | option to the |
1948 | .B set | |
1949 | command (see | |
1950 | .SM | |
1951 | .B SHELL BUILTIN COMMANDS | |
1952 | below). | |
1953 | .SS Tilde Expansion | |
1954 | .PP | |
cce855bc JA |
1955 | If a word begins with an unquoted tilde character (`\fB~\fP'), all of |
1956 | the characters preceding the first unquoted slash (or all characters, | |
1957 | if there is no unquoted slash) are considered a \fItilde-prefix\fP. | |
1958 | If none of the characters in the tilde-prefix are quoted, the | |
1959 | characters in the tilde-prefix following the tilde are treated as a | |
1960 | possible \fIlogin name\fP. | |
1961 | If this login name is the null string, the tilde is replaced with the | |
1962 | value of the shell parameter | |
726f6388 JA |
1963 | .SM |
1964 | .BR HOME . | |
1965 | If | |
1966 | .SM | |
1967 | .B HOME | |
cce855bc JA |
1968 | is unset, the home directory of the user executing the shell is |
1969 | substituted instead. | |
1970 | Otherwise, the tilde-prefix is replaced with the home directory | |
1971 | associated with the specified login name. | |
726f6388 | 1972 | .PP |
cce855bc | 1973 | If the tilde-prefix is a `~+', the value of the shell variable |
726f6388 JA |
1974 | .SM |
1975 | .B PWD | |
cce855bc JA |
1976 | replaces the tilde-prefix. |
1977 | If the tilde-prefix is a `~\-', the value of the shell variable | |
1978 | .SM | |
1979 | .BR OLDPWD , | |
1980 | if it is set, is substituted. | |
1981 | If the characters following the tilde in the tilde-prefix consist | |
1982 | of a number \fIN\fP, optionally prefixed | |
1983 | by a `+' or a `\-', the tilde-prefix is replaced with the corresponding | |
1984 | element from the directory stack, as it would be displayed by the | |
1985 | .B dirs | |
1986 | builtin invoked with the tilde-prefix as an argument. | |
1987 | If the characters following the tilde in the tilde-prefix consist of a | |
1988 | number without a leading `+' or `\-', `+' is assumed. | |
1989 | .PP | |
1990 | If the login name is invalid, or the tilde expansion fails, the word | |
1991 | is unchanged. | |
726f6388 | 1992 | .PP |
cce855bc JA |
1993 | Each variable assignment is checked for unquoted tilde-prefixes immediately |
1994 | following a | |
726f6388 JA |
1995 | .B : |
1996 | or | |
1997 | .BR = . | |
cce855bc JA |
1998 | In these cases, tilde expansion is also performed. |
1999 | Consequently, one may use file names with tildes in assignments to | |
726f6388 JA |
2000 | .SM |
2001 | .BR PATH , | |
2002 | .SM | |
2003 | .BR MAILPATH , | |
2004 | and | |
2005 | .SM | |
2006 | .BR CDPATH , | |
2007 | and the shell assigns the expanded value. | |
2008 | .SS Parameter Expansion | |
2009 | .PP | |
2010 | The `\fB$\fP' character introduces parameter expansion, | |
2011 | command substitution, or arithmetic expansion. The parameter name | |
2012 | or symbol to be expanded may be enclosed in braces, which | |
2013 | are optional but serve to protect the variable to be expanded from | |
2014 | characters immediately following it which could be | |
2015 | interpreted as part of the name. | |
2016 | .PP | |
cce855bc JA |
2017 | When braces are used, the matching ending brace is the first `\fB}\fP' |
2018 | not escaped by a backslash or within a quoted string, and not within an | |
2019 | embedded arithmetic expansion, command substitution, or paramter | |
2020 | expansion. | |
2021 | .PP | |
726f6388 JA |
2022 | .PD 0 |
2023 | .TP | |
2024 | ${\fIparameter\fP} | |
2025 | The value of \fIparameter\fP is substituted. The braces are required | |
2026 | when | |
2027 | .I parameter | |
2028 | is a positional parameter with more than one digit, | |
2029 | or when | |
2030 | .I parameter | |
2031 | is followed by a character which is not to be | |
2032 | interpreted as part of its name. | |
2033 | .PD | |
2034 | .PP | |
ccc6cda3 JA |
2035 | If the first character of \fIparameter\fP is an exclamation point, |
2036 | a level of variable indirection is introduced. | |
2037 | \fBBash\fP uses the value of the variable formed from the rest of | |
2038 | \fIparameter\fP as the name of the variable; this variable is then | |
bb70624e | 2039 | expanded and that value is used in the rest of the substitution, rather |
ccc6cda3 JA |
2040 | than the value of \fIparameter\fP itself. |
2041 | This is known as \fIindirect expansion\fP. | |
bb70624e JA |
2042 | The exception to this is the expansion of ${!\fIprefix\fP*} |
2043 | described below. | |
ccc6cda3 | 2044 | .PP |
726f6388 JA |
2045 | In each of the cases below, \fIword\fP is subject to tilde expansion, |
2046 | parameter expansion, command substitution, and arithmetic expansion. | |
ccc6cda3 JA |
2047 | When not performing substring expansion, \fBbash\fP tests for a parameter |
2048 | that is unset or null; omitting the colon results in a test only for a | |
2049 | parameter that is unset. | |
726f6388 JA |
2050 | .PP |
2051 | .PD 0 | |
2052 | .TP | |
2053 | ${\fIparameter\fP\fB:\-\fP\fIword\fP} | |
2054 | \fBUse Default Values\fP. If | |
2055 | .I parameter | |
2056 | is unset or null, the expansion of | |
2057 | .I word | |
2058 | is substituted. Otherwise, the value of | |
2059 | .I parameter | |
2060 | is substituted. | |
2061 | .TP | |
2062 | ${\fIparameter\fP\fB:=\fP\fIword\fP} | |
2063 | \fBAssign Default Values\fP. | |
2064 | If | |
2065 | .I parameter | |
2066 | is unset or null, the expansion of | |
2067 | .I word | |
2068 | is assigned to | |
2069 | .IR parameter . | |
2070 | The value of | |
2071 | .I parameter | |
2072 | is then substituted. Positional parameters and special parameters may | |
2073 | not be assigned to in this way. | |
2074 | .TP | |
2075 | ${\fIparameter\fP\fB:?\fP\fIword\fP} | |
2076 | \fBDisplay Error if Null or Unset\fP. | |
2077 | If | |
2078 | .I parameter | |
2079 | is null or unset, the expansion of \fIword\fP (or a message to that effect | |
2080 | if | |
2081 | .I word | |
2082 | is not present) is written to the standard error and the shell, if it | |
2083 | is not interactive, exits. Otherwise, the value of \fIparameter\fP is | |
2084 | substituted. | |
2085 | .TP | |
2086 | ${\fIparameter\fP\fB:+\fP\fIword\fP} | |
2087 | \fBUse Alternate Value\fP. | |
2088 | If | |
2089 | .I parameter | |
2090 | is null or unset, nothing is substituted, otherwise the expansion of | |
2091 | .I word | |
2092 | is substituted. | |
2093 | .TP | |
ccc6cda3 JA |
2094 | .PD 0 |
2095 | ${\fIparameter\fP\fB:\fP\fIoffset\fP} | |
2096 | .TP | |
2097 | ${\fIparameter\fP\fB:\fP\fIoffset\fP\fB:\fP\fIlength\fP} | |
2098 | .PD | |
2099 | \fBSubstring Expansion.\fP | |
bb70624e JA |
2100 | Expands to up to \fIlength\fP characters of \fIparameter\fP |
2101 | starting at the character specified by \fIoffset\fP. | |
ccc6cda3 | 2102 | If \fIlength\fP is omitted, expands to the substring of |
bb70624e | 2103 | \fIparameter\fP starting at the character specified by \fIoffset\fP. |
ccc6cda3 JA |
2104 | \fIlength\fP and \fIoffset\fP are arithmetic expressions (see |
2105 | .SM | |
2106 | .B | |
2107 | ARITHMETIC EVALUATION | |
2108 | below). | |
2109 | \fIlength\fP must evaluate to a number greater than or equal to zero. | |
2110 | If \fIoffset\fP evaluates to a number less than zero, the value | |
2111 | is used as an offset from the end of the value of \fIparameter\fP. | |
2112 | If \fIparameter\fP is \fB@\fP, the result is \fIlength\fP positional | |
2113 | parameters beginning at \fIoffset\fP. | |
2114 | If \fIparameter\fP is an array name indexed by @ or *, | |
2115 | the result is the \fIlength\fP | |
2116 | members of the array beginning with ${\fIparameter\fP[\fIoffset\fP]}. | |
cce855bc JA |
2117 | Substring indexing is zero-based unless the positional parameters |
2118 | are used, in which case the indexing starts at 1. | |
ccc6cda3 | 2119 | .TP |
bb70624e JA |
2120 | ${\fB!\fP\fIprefix\fP\fB*\fP} |
2121 | Expands to the names of variables whose names begin with \fIprefix\fP, | |
2122 | separated by the first character of the | |
2123 | .SM | |
2124 | .B IFS | |
2125 | special variable. | |
2126 | .TP | |
726f6388 JA |
2127 | ${\fB#\fP\fIparameter\fP} |
2128 | The length in characters of the value of \fIparameter\fP is substituted. | |
ccc6cda3 JA |
2129 | If |
2130 | .I parameter | |
2131 | is | |
726f6388 JA |
2132 | .B * |
2133 | or | |
2134 | .BR @ , | |
cce855bc | 2135 | the value substituted is the number of positional parameters. |
ccc6cda3 JA |
2136 | If |
2137 | .I parameter | |
2138 | is an array name subscripted by | |
726f6388 | 2139 | .B * |
ccc6cda3 JA |
2140 | or |
2141 | .BR @ , | |
cce855bc | 2142 | the value substituted is the number of elements in the array. |
726f6388 JA |
2143 | .TP |
2144 | .PD 0 | |
2145 | ${\fIparameter\fP\fB#\fP\fIword\fP} | |
2146 | .TP | |
2147 | ${\fIparameter\fP\fB##\fP\fIword\fP} | |
2148 | .PD | |
2149 | The | |
2150 | .I word | |
2151 | is expanded to produce a pattern just as in pathname | |
2152 | expansion. If the pattern matches the beginning of | |
2153 | the value of | |
2154 | .IR parameter , | |
cce855bc | 2155 | then the result of the expansion is the expanded value of |
726f6388 | 2156 | .I parameter |
ccc6cda3 JA |
2157 | with the shortest matching pattern (the ``\fB#\fP'' case) or the |
2158 | longest matching pattern (the ``\fB##\fP'' case) deleted. | |
2159 | If | |
2160 | .I parameter | |
2161 | is | |
2162 | .B @ | |
2163 | or | |
2164 | .BR * , | |
2165 | the pattern removal operation is applied to each positional | |
2166 | parameter in turn, and the expansion is the resultant list. | |
2167 | If | |
2168 | .I parameter | |
2169 | is an array variable subscripted with | |
2170 | .B @ | |
2171 | or | |
2172 | .BR * , | |
2173 | the pattern removal operation is applied to each member of the | |
2174 | array in turn, and the expansion is the resultant list. | |
726f6388 JA |
2175 | .TP |
2176 | .PD 0 | |
2177 | ${\fIparameter\fP\fB%\fP\fIword\fP} | |
2178 | .TP | |
2179 | ${\fIparameter\fP\fB%%\fP\fIword\fP} | |
2180 | .PD | |
2181 | The \fIword\fP is expanded to produce a pattern just as in | |
ccc6cda3 | 2182 | pathname expansion. |
cce855bc | 2183 | If the pattern matches a trailing portion of the expanded value of |
726f6388 | 2184 | .IR parameter , |
cce855bc | 2185 | then the result of the expansion is the expanded value of |
726f6388 | 2186 | .I parameter |
ccc6cda3 JA |
2187 | with the shortest matching pattern (the ``\fB%\fP'' case) or the |
2188 | longest matching pattern (the ``\fB%%\fP'' case) deleted. | |
2189 | If | |
2190 | .I parameter | |
2191 | is | |
2192 | .B @ | |
2193 | or | |
2194 | .BR * , | |
2195 | the pattern removal operation is applied to each positional | |
2196 | parameter in turn, and the expansion is the resultant list. | |
2197 | If | |
2198 | .I parameter | |
2199 | is an array variable subscripted with | |
2200 | .B @ | |
2201 | or | |
2202 | .BR * , | |
2203 | the pattern removal operation is applied to each member of the | |
2204 | array in turn, and the expansion is the resultant list. | |
2205 | .TP | |
2206 | .PD 0 | |
2207 | ${\fIparameter\fP\fB/\fP\fIpattern\fP\fB/\fP\fIstring\fP} | |
2208 | .TP | |
2209 | ${\fIparameter\fP\fB//\fP\fIpattern\fP\fB/\fP\fIstring\fP} | |
2210 | .PD | |
2211 | The \fIpattern\fP is expanded to produce a pattern just as in | |
2212 | pathname expansion. | |
2213 | \fIParameter\fP is expanded and the longest match of \fIpattern\fP | |
2214 | against its value is replaced with \fIstring\fP. | |
2215 | In the first form, only the first match is replaced. | |
2216 | The second form causes all matches of \fIpattern\fP to be | |
2217 | replaced with \fIstring\fP. | |
2218 | If \fIpattern\fP begins with \fB#\fP, it must match at the beginning | |
b72432fd | 2219 | of the expanded value of \fIparameter\fP. |
ccc6cda3 | 2220 | If \fIpattern\fP begins with \fB%\fP, it must match at the end |
b72432fd | 2221 | of the expanded value of \fIparameter\fP. |
ccc6cda3 JA |
2222 | If \fIstring\fP is null, matches of \fIpattern\fP are deleted |
2223 | and the \fB/\fP following \fIpattern\fP may be omitted. | |
2224 | If | |
2225 | .I parameter | |
2226 | is | |
2227 | .B @ | |
2228 | or | |
2229 | .BR * , | |
2230 | the substitution operation is applied to each positional | |
2231 | parameter in turn, and the expansion is the resultant list. | |
2232 | If | |
2233 | .I parameter | |
2234 | is an array variable subscripted with | |
2235 | .B @ | |
2236 | or | |
2237 | .BR * , | |
2238 | the substitution operation is applied to each member of the | |
2239 | array in turn, and the expansion is the resultant list. | |
726f6388 JA |
2240 | .SS Command Substitution |
2241 | .PP | |
cce855bc | 2242 | \fICommand substitution\fP allows the output of a command to replace |
726f6388 JA |
2243 | the command name. There are two forms: |
2244 | .PP | |
2245 | .RS | |
2246 | .PP | |
2247 | \fB$(\fP\fIcommand\fP\|\fB)\fP | |
2248 | .RE | |
2249 | or | |
2250 | .RS | |
2251 | \fB`\fP\fIcommand\fP\fB`\fP | |
2252 | .RE | |
2253 | .PP | |
ccc6cda3 | 2254 | .B Bash |
726f6388 JA |
2255 | performs the expansion by executing \fIcommand\fP and |
2256 | replacing the command substitution with the standard output of the | |
2257 | command, with any trailing newlines deleted. | |
cce855bc JA |
2258 | Embedded newlines are not deleted, but they may be removed during |
2259 | word splitting. | |
2260 | The command substitution \fB$(cat \fIfile\fP)\fR can be replaced by | |
2261 | the equivalent but faster \fB$(< \fIfile\fP)\fR. | |
726f6388 | 2262 | .PP |
ccc6cda3 | 2263 | When the old-style backquote form of substitution is used, |
726f6388 JA |
2264 | backslash retains its literal meaning except when followed by |
2265 | .BR $ , | |
2266 | .BR ` , | |
2267 | or | |
2268 | .BR \e . | |
cce855bc JA |
2269 | The first backquote not preceded by a backslash terminates the |
2270 | command substitution. | |
726f6388 JA |
2271 | When using the $(\^\fIcommand\fP\|) form, all characters between the |
2272 | parentheses make up the command; none are treated specially. | |
2273 | .PP | |
cce855bc | 2274 | Command substitutions may be nested. To nest when using the backquoted form, |
726f6388 JA |
2275 | escape the inner backquotes with backslashes. |
2276 | .PP | |
2277 | If the substitution appears within double quotes, word splitting and | |
2278 | pathname expansion are not performed on the results. | |
2279 | .SS Arithmetic Expansion | |
2280 | .PP | |
2281 | Arithmetic expansion allows the evaluation of an arithmetic expression | |
ccc6cda3 | 2282 | and the substitution of the result. The format for arithmetic expansion is: |
726f6388 JA |
2283 | .RS |
2284 | .PP | |
726f6388 JA |
2285 | \fB$((\fP\fIexpression\fP\fB))\fP |
2286 | .RE | |
2287 | .PP | |
2288 | The | |
2289 | .I expression | |
2290 | is treated as if it were within double quotes, but a double quote | |
ccc6cda3 JA |
2291 | inside the parentheses is not treated specially. |
2292 | All tokens in the expression undergo parameter expansion, string | |
2293 | expansion, command substitution, and quote removal. | |
2294 | Arithmetic substitutions may be nested. | |
726f6388 JA |
2295 | .PP |
2296 | The evaluation is performed according to the rules listed below under | |
2297 | .SM | |
2298 | .BR "ARITHMETIC EVALUATION" . | |
2299 | If | |
2300 | .I expression | |
2301 | is invalid, | |
2302 | .B bash | |
2303 | prints a message indicating failure and no substitution occurs. | |
2304 | .SS Process Substitution | |
2305 | .PP | |
2306 | \fIProcess substitution\fP is supported on systems that support named | |
2307 | pipes (\fIFIFOs\fP) or the \fB/dev/fd\fP method of naming open files. | |
2308 | It takes the form of | |
2309 | \fB<(\fP\fIlist\^\fP\fB)\fP | |
2310 | or | |
2311 | \fB>(\fP\fIlist\^\fP\fB)\fP. | |
2312 | The process \fIlist\fP is run with its input or output connected to a | |
2313 | \fIFIFO\fP or some file in \fB/dev/fd\fP. The name of this file is | |
2314 | passed as an argument to the current command as the result of the | |
2315 | expansion. If the \fB>(\fP\fIlist\^\fP\fB)\fP form is used, writing to | |
2316 | the file will provide input for \fIlist\fP. If the | |
2317 | \fB<(\fP\fIlist\^\fP\fB)\fP form is used, the file passed as an | |
2318 | argument should be read to obtain the output of \fIlist\fP. | |
2319 | .PP | |
bb70624e | 2320 | When available, process substitution is performed |
ccc6cda3 JA |
2321 | simultaneously with parameter and variable expansion, |
2322 | command substitution, | |
2323 | and arithmetic expansion. | |
726f6388 JA |
2324 | .SS Word Splitting |
2325 | .PP | |
2326 | The shell scans the results of | |
2327 | parameter expansion, | |
2328 | command substitution, | |
2329 | and | |
2330 | arithmetic expansion | |
2331 | that did not occur within double quotes for | |
2332 | .IR "word splitting" . | |
2333 | .PP | |
2334 | The shell treats each character of | |
2335 | .SM | |
2336 | .B IFS | |
2337 | as a delimiter, and splits the results of the other | |
ccc6cda3 | 2338 | expansions into words on these characters. If |
726f6388 JA |
2339 | .SM |
2340 | .B IFS | |
ccc6cda3 JA |
2341 | is unset, or its |
2342 | value is exactly | |
726f6388 JA |
2343 | .BR <space><tab><newline> , |
2344 | the default, then | |
2345 | any sequence of | |
2346 | .SM | |
2347 | .B IFS | |
2348 | characters serves to delimit words. If | |
2349 | .SM | |
2350 | .B IFS | |
2351 | has a value other than the default, then sequences of | |
2352 | the whitespace characters | |
2353 | .B space | |
2354 | and | |
2355 | .B tab | |
2356 | are ignored at the beginning and end of the | |
2357 | word, as long as the whitespace character is in the | |
2358 | value of | |
2359 | .SM | |
2360 | .BR IFS | |
2361 | (an | |
2362 | .SM | |
2363 | .B IFS | |
2364 | whitespace character). | |
2365 | Any character in | |
2366 | .SM | |
2367 | .B IFS | |
2368 | that is not | |
2369 | .SM | |
2370 | .B IFS | |
2371 | whitespace, along with any adjacent | |
2372 | .SM | |
2373 | .B IFS | |
2374 | whitespace characters, delimits a field. | |
2375 | A sequence of | |
2376 | .SM | |
2377 | .B IFS | |
2378 | whitespace characters is also treated as a delimiter. | |
2379 | If the value of | |
2380 | .SM | |
2381 | .B IFS | |
2382 | is null, no word splitting occurs. | |
726f6388 | 2383 | .PP |
ccc6cda3 JA |
2384 | Explicit null arguments (\^\f3"\^"\fP or \^\f3'\^'\fP\^) are retained. |
2385 | Unquoted implicit null arguments, resulting from the expansion of | |
bb70624e | 2386 | parameters that have no values, are removed. |
ccc6cda3 JA |
2387 | If a parameter with no value is expanded within double quotes, a |
2388 | null argument results and is retained. | |
726f6388 JA |
2389 | .PP |
2390 | Note that if no expansion occurs, no splitting | |
2391 | is performed. | |
2392 | .SS Pathname Expansion | |
2393 | .PP | |
2394 | After word splitting, | |
2395 | unless the | |
2396 | .B \-f | |
2397 | option has been set, | |
2398 | .B bash | |
ccc6cda3 | 2399 | scans each word for the characters |
726f6388 JA |
2400 | .BR * , |
2401 | .BR ? , | |
2402 | and | |
2403 | .BR [ . | |
2404 | If one of these characters appears, then the word is | |
2405 | regarded as a | |
2406 | .IR pattern , | |
2407 | and replaced with an alphabetically sorted list of | |
ccc6cda3 JA |
2408 | file names matching the pattern. |
2409 | If no matching file names are found, | |
2410 | and the shell option | |
2411 | .B nullglob | |
2412 | is disabled, the word is left unchanged. | |
cce855bc JA |
2413 | If the |
2414 | .B nullglob | |
2415 | option is set, and no matches are found, | |
726f6388 | 2416 | the word is removed. |
cce855bc JA |
2417 | If the shell option |
2418 | .B nocaseglob | |
2419 | is enabled, the match is performed without regard to the case | |
2420 | of alphabetic characters. | |
ccc6cda3 | 2421 | When a pattern is used for pathname expansion, |
726f6388 JA |
2422 | the character |
2423 | .B ``.'' | |
2424 | at the start of a name or immediately following a slash | |
ccc6cda3 JA |
2425 | must be matched explicitly, unless the shell option |
2426 | .B dotglob | |
2427 | is set. | |
cce855bc JA |
2428 | When matching a pathname, the slash character must always be |
2429 | matched explicitly. | |
ccc6cda3 | 2430 | In other cases, the |
726f6388 JA |
2431 | .B ``.'' |
2432 | character is not treated specially. | |
ccc6cda3 JA |
2433 | See the description of |
2434 | .B shopt | |
2435 | below under | |
2436 | .SM | |
2437 | .B SHELL BUILTIN COMMANDS | |
2438 | for a description of the | |
cce855bc JA |
2439 | .BR nocaseglob , |
2440 | .BR nullglob , | |
ccc6cda3 JA |
2441 | and |
2442 | .B dotglob | |
2443 | shell options. | |
2444 | .PP | |
2445 | The | |
2446 | .SM | |
2447 | .B GLOBIGNORE | |
2448 | shell variable may be used to restrict the set of file names matching a | |
2449 | .IR pattern . | |
2450 | If | |
2451 | .SM | |
2452 | .B GLOBIGNORE | |
2453 | is set, each matching file name that also matches one of the patterns in | |
2454 | .SM | |
2455 | .B GLOBIGNORE | |
2456 | is removed from the list of matches. | |
2457 | The file names | |
2458 | .B ``.'' | |
2459 | and | |
2460 | .B ``..'' | |
2461 | are always ignored, even when | |
2462 | .SM | |
2463 | .B GLOBIGNORE | |
2464 | is set. However, setting | |
2465 | .SM | |
2466 | .B GLOBIGNORE | |
2467 | has the effect of enabling the | |
2468 | .B dotglob | |
2469 | shell option, so all other file names beginning with a | |
2470 | .B ``.'' | |
2471 | will match. | |
2472 | To get the old behavior of ignoring file names beginning with a | |
2473 | .BR ``.'' , | |
2474 | make | |
2475 | .B ``.*'' | |
2476 | one of the patterns in | |
2477 | .SM | |
2478 | .BR GLOBIGNORE . | |
2479 | The | |
2480 | .B dotglob | |
2481 | option is disabled when | |
2482 | .SM | |
2483 | .B GLOBIGNORE | |
2484 | is unset. | |
726f6388 | 2485 | .PP |
cce855bc JA |
2486 | \fBPattern Matching\fP |
2487 | .PP | |
2488 | Any character that appears in a pattern, other than the special pattern | |
2489 | characters described below, matches itself. The NUL character may not | |
2490 | occur in a pattern. The special pattern characters must be quoted if | |
2491 | they are to be matched literally. | |
2492 | .PP | |
726f6388 JA |
2493 | The special pattern characters have the following meanings: |
2494 | .PP | |
2495 | .PD 0 | |
2496 | .TP | |
2497 | .B * | |
2498 | Matches any string, including the null string. | |
2499 | .TP | |
2500 | .B ? | |
2501 | Matches any single character. | |
2502 | .TP | |
2503 | .B [...] | |
2504 | Matches any one of the enclosed characters. A pair of characters | |
2505 | separated by a minus sign denotes a | |
2506 | .IR range ; | |
2507 | any character lexically between those two characters, inclusive, | |
2508 | is matched. If the first character following the | |
2509 | .B [ | |
2510 | is a | |
2511 | .B ! | |
2512 | or a | |
2513 | .B ^ | |
ccc6cda3 JA |
2514 | then any character not enclosed is matched. |
2515 | A | |
726f6388 | 2516 | .B \- |
726f6388 JA |
2517 | may be matched by including it as the first or last character |
2518 | in the set. | |
ccc6cda3 JA |
2519 | A |
2520 | .B ] | |
2521 | may be matched by including it as the first character | |
2522 | in the set. | |
cce855bc JA |
2523 | .br |
2524 | .if t .sp 0.5 | |
2525 | .if n .sp 1 | |
2526 | Within | |
2527 | .B [ | |
2528 | and | |
2529 | .BR ] , | |
2530 | \fIcharacter classes\fP can be specified using the syntax | |
2531 | \fB[:\fP\fIclass\fP\fB:]\fP, where \fIclass\fP is one of the | |
2532 | following classes defined in the POSIX.2 standard: | |
2533 | .PP | |
2534 | .RS | |
2535 | .B | |
2536 | .if n alnum alpha ascii blank cntrl digit graph lower print punct space upper xdigit | |
2537 | .if t alnum alpha ascii blank cntrl digit graph lower print punct space upper xdigit | |
2538 | .br | |
2539 | A character class matches any character belonging to that class. | |
2540 | .br | |
2541 | .if t .sp 0.5 | |
2542 | .if n .sp 1 | |
2543 | Within | |
2544 | .B [ | |
2545 | and | |
2546 | .BR ] , | |
2547 | an \fIequivalence class\fP can be specified using the syntax | |
2548 | \fB[=\fP\fIc\fP\fB=]\fP, which matches all characters with the | |
2549 | same collation weight (as defined by the current locale) as | |
2550 | the character \fIc\fP. | |
2551 | .br | |
2552 | .if t .sp 0.5 | |
2553 | .if n .sp 1 | |
2554 | Within | |
2555 | .B [ | |
2556 | and | |
2557 | .BR ] , | |
2558 | the syntax \fB[.\fP\fIsymbol\fP\fB.]\fP matches the collating symbol | |
2559 | \fIsymbol\fP. | |
2560 | .RE | |
2561 | .PD | |
2562 | .PP | |
2563 | If the \fBextglob\fP shell option is enabled using the \fBshopt\fP | |
2564 | builtin, several extended pattern matching operators are recognized. | |
bb70624e | 2565 | In the following description, a \fIpattern-list\fP is a list of one |
cce855bc JA |
2566 | or more patterns separated by a \fB|\fP. |
2567 | Composite patterns may be formed using one or more of the following | |
2568 | sub-patterns: | |
2569 | .sp 1 | |
2570 | .PD 0 | |
2571 | .RS | |
2572 | .TP | |
2573 | \fB?(\fP\^\fIpattern-list\^\fP\fB)\fP | |
2574 | Matches zero or one occurrence of the given patterns | |
2575 | .TP | |
2576 | \fB*(\fP\^\fIpattern-list\^\fP\fB)\fP | |
2577 | Matches zero or more occurrences of the given patterns | |
2578 | .TP | |
2579 | \fB+(\fP\^\fIpattern-list\^\fP\fB)\fP | |
2580 | Matches one or more occurrences of the given patterns | |
2581 | .TP | |
2582 | \fB@(\fP\^\fIpattern-list\^\fP\fB)\fP | |
2583 | Matches exactly one of the given patterns | |
2584 | .TP | |
2585 | \fB!(\fP\^\fIpattern-list\^\fP\fB)\fP | |
2586 | Matches anything except one of the given patterns | |
2587 | .RE | |
726f6388 JA |
2588 | .PD |
2589 | .SS Quote Removal | |
2590 | .PP | |
2591 | After the preceding expansions, all unquoted occurrences of the | |
2592 | characters | |
2593 | .BR \e , | |
cce855bc | 2594 | .BR ' , |
ccc6cda3 JA |
2595 | and \^\f3"\fP\^ that did not result from one of the above |
2596 | expansions are removed. | |
726f6388 JA |
2597 | .SH REDIRECTION |
2598 | Before a command is executed, its input and output | |
2599 | may be | |
2600 | .I redirected | |
2601 | using a special notation interpreted by the shell. | |
2602 | Redirection may also be used to open and close files for the | |
2603 | current shell execution environment. The following redirection | |
2604 | operators may precede or appear anywhere within a | |
2605 | .I simple command | |
2606 | or may follow a | |
2607 | .IR command . | |
2608 | Redirections are processed in the order they appear, from | |
2609 | left to right. | |
2610 | .PP | |
2611 | In the following descriptions, if the file descriptor number is | |
2612 | omitted, and the first character of the redirection operator is | |
2613 | .BR < , | |
2614 | the redirection refers to the standard input (file descriptor | |
2615 | 0). If the first character of the redirection operator is | |
2616 | .BR > , | |
2617 | the redirection refers to the standard output (file descriptor | |
2618 | 1). | |
2619 | .PP | |
cce855bc JA |
2620 | The word following the redirection operator in the following |
2621 | descriptions, unless otherwise noted, is subjected to brace expansion, | |
2622 | tilde expansion, parameter expansion, command substitution, arithmetic | |
bb70624e | 2623 | expansion, quote removal, pathname expansion, and word splitting. |
cce855bc | 2624 | If it expands to more than one word, |
726f6388 JA |
2625 | .B bash |
2626 | reports an error. | |
2627 | .PP | |
2628 | Note that the order of redirections is significant. For example, | |
2629 | the command | |
2630 | .RS | |
2631 | .PP | |
2632 | ls \fB>\fP dirlist 2\fB>&\fP1 | |
2633 | .RE | |
2634 | .PP | |
2635 | directs both standard output and standard error to the file | |
2636 | .IR dirlist , | |
2637 | while the command | |
2638 | .RS | |
2639 | .PP | |
2640 | ls 2\fB>&\fP1 \fB>\fP dirlist | |
2641 | .RE | |
2642 | .PP | |
2643 | directs only the standard output to file | |
2644 | .IR dirlist , | |
2645 | because the standard error was duplicated as standard output | |
2646 | before the standard output was redirected to | |
2647 | .IR dirlist . | |
cce855bc | 2648 | .PP |
bb70624e JA |
2649 | \fBBash\fP handles several filenames specially when they are used in |
2650 | redirections, as described in the following table: | |
2651 | .RS | |
2652 | .PP | |
2653 | .PD 0 | |
2654 | .TP | |
2655 | .B /dev/fd/\fIfd\fP | |
2656 | If \fIfd\fP is a valid integer, file descriptor \fIfd\fP is duplicated. | |
2657 | .TP | |
2658 | .B /dev/stdin | |
2659 | File descriptor 0 is duplicated. | |
2660 | .TP | |
2661 | .B /dev/stdout | |
2662 | File descriptor 1 is duplicated. | |
2663 | .TP | |
2664 | .B /dev/stderr | |
2665 | File descriptor 2 is duplicated. | |
2666 | .TP | |
2667 | .B /dev/tcp/\fIhost\fP/\fIport\fP | |
2668 | If \fIhost\fP is a valid hostname or Internet address, and \fIport\fP | |
2669 | is an integer port number, \fBbash\fP attempts to open a TCP connection | |
2670 | to the corresponding socket. | |
2671 | .TP | |
2672 | .B /dev/udp/\fIhost\fP/\fIport\fP | |
2673 | If \fIhost\fP is a valid hostname or Internet address, and \fIport\fP | |
2674 | is an integer port number, \fBbash\fP attempts to open a UDP connection | |
2675 | to the corresponding socket. | |
2676 | .PD | |
2677 | .RE | |
2678 | .PP | |
cce855bc | 2679 | A failure to open or create a file causes the redirection to fail. |
726f6388 JA |
2680 | .SS Redirecting Input |
2681 | .PP | |
2682 | Redirection of input causes the file whose name results from | |
2683 | the expansion of | |
2684 | .I word | |
2685 | to be opened for reading on file descriptor | |
2686 | .IR n , | |
2687 | or the standard input (file descriptor 0) if | |
2688 | .I n | |
2689 | is not specified. | |
2690 | .PP | |
2691 | The general format for redirecting input is: | |
2692 | .RS | |
2693 | .PP | |
2694 | [\fIn\fP]\fB<\fP\fIword\fP | |
2695 | .RE | |
2696 | .SS Redirecting Output | |
2697 | .PP | |
2698 | Redirection of output causes the file whose name results from | |
2699 | the expansion of | |
2700 | .I word | |
2701 | to be opened for writing on file descriptor | |
2702 | .IR n , | |
2703 | or the standard output (file descriptor 1) if | |
2704 | .I n | |
2705 | is not specified. If the file does not exist it is created; | |
2706 | if it does exist it is truncated to zero size. | |
2707 | .PP | |
2708 | The general format for redirecting output is: | |
2709 | .RS | |
2710 | .PP | |
2711 | [\fIn\fP]\fB>\fP\fIword\fP | |
2712 | .RE | |
2713 | .PP | |
2714 | If the redirection operator is | |
ccc6cda3 JA |
2715 | .BR > , |
2716 | and the | |
cce855bc | 2717 | .B noclobber |
ccc6cda3 JA |
2718 | option to the |
2719 | .B set | |
bb70624e | 2720 | builtin has been enabled, the redirection will fail if the file |
cce855bc JA |
2721 | whose name results from the expansion of \fIword\fP exists and is |
2722 | a regular file. | |
ccc6cda3 | 2723 | If the redirection operator is |
726f6388 | 2724 | .BR >| , |
cce855bc JA |
2725 | or the redirection operator is |
2726 | .B > | |
2727 | and the | |
2728 | .B noclobber | |
726f6388 JA |
2729 | option to the |
2730 | .B set | |
cce855bc | 2731 | builtin command is not enabled, the redirection is attempted even |
ccc6cda3 | 2732 | if the file named by \fIword\fP exists. |
726f6388 JA |
2733 | .SS Appending Redirected Output |
2734 | .PP | |
2735 | Redirection of output in this fashion | |
2736 | causes the file whose name results from | |
2737 | the expansion of | |
2738 | .I word | |
2739 | to be opened for appending on file descriptor | |
2740 | .IR n , | |
2741 | or the standard output (file descriptor 1) if | |
2742 | .I n | |
2743 | is not specified. If the file does not exist it is created. | |
2744 | .PP | |
2745 | The general format for appending output is: | |
2746 | .RS | |
2747 | .PP | |
2748 | [\fIn\fP]\fB>>\fP\fIword\fP | |
2749 | .RE | |
2750 | .PP | |
2751 | .SS Redirecting Standard Output and Standard Error | |
2752 | .PP | |
2753 | .B Bash | |
2754 | allows both the | |
2755 | standard output (file descriptor 1) and | |
2756 | the standard error output (file descriptor 2) | |
2757 | to be redirected to the file whose name is the | |
2758 | expansion of | |
2759 | .I word | |
2760 | with this construct. | |
2761 | .PP | |
2762 | There are two formats for redirecting standard output and | |
2763 | standard error: | |
2764 | .RS | |
2765 | .PP | |
2766 | \fB&>\fP\fIword\fP | |
2767 | .RE | |
2768 | and | |
2769 | .RS | |
2770 | \fB>&\fP\fIword\fP | |
2771 | .RE | |
2772 | .PP | |
2773 | Of the two forms, the first is preferred. | |
2774 | This is semantically equivalent to | |
2775 | .RS | |
2776 | .PP | |
2777 | \fB>\fP\fIword\fP 2\fB>&\fP1 | |
2778 | .RE | |
2779 | .SS Here Documents | |
2780 | .PP | |
2781 | This type of redirection instructs the shell to read input from the | |
2782 | current source until a line containing only | |
2783 | .I word | |
2784 | (with no trailing blanks) | |
2785 | is seen. All of | |
2786 | the lines read up to that point are then used as the standard | |
2787 | input for a command. | |
2788 | .PP | |
2789 | The format of here-documents is as follows: | |
2790 | .RS | |
2791 | .PP | |
2792 | .nf | |
2793 | \fB<<\fP[\fB\-\fP]\fIword\fP | |
ccc6cda3 | 2794 | \fIhere\-document\fP |
726f6388 JA |
2795 | \fIdelimiter\fP |
2796 | .fi | |
2797 | .RE | |
2798 | .PP | |
bb70624e JA |
2799 | No parameter expansion, command substitution, arithmetic expansion, |
2800 | or pathname expansion is performed on | |
726f6388 JA |
2801 | .IR word . |
2802 | If any characters in | |
2803 | .I word | |
2804 | are quoted, the | |
2805 | .I delimiter | |
2806 | is the result of quote removal on | |
2807 | .IR word , | |
cce855bc JA |
2808 | and the lines in the here-document are not expanded. |
2809 | If \fIword\fP is unquoted, | |
726f6388 JA |
2810 | all lines of the here-document are subjected to parameter expansion, |
2811 | command substitution, and arithmetic expansion. In the latter | |
bb70624e | 2812 | case, the character sequence |
726f6388 JA |
2813 | .B \e<newline> |
2814 | is ignored, and | |
2815 | .B \e | |
2816 | must be used to quote the characters | |
2817 | .BR \e , | |
2818 | .BR $ , | |
2819 | and | |
2820 | .BR ` . | |
2821 | .PP | |
2822 | If the redirection operator is | |
2823 | .BR <<\- , | |
2824 | then all leading tab characters are stripped from input lines and the | |
2825 | line containing | |
2826 | .IR delimiter . | |
2827 | This allows | |
2828 | here-documents within shell scripts to be indented in a | |
2829 | natural fashion. | |
2830 | .SS "Duplicating File Descriptors" | |
2831 | .PP | |
2832 | The redirection operator | |
2833 | .RS | |
2834 | .PP | |
2835 | [\fIn\fP]\fB<&\fP\fIword\fP | |
2836 | .RE | |
2837 | .PP | |
2838 | is used to duplicate input file descriptors. | |
2839 | If | |
2840 | .I word | |
2841 | expands to one or more digits, the file descriptor denoted by | |
2842 | .I n | |
cce855bc JA |
2843 | is made to be a copy of that file descriptor. |
2844 | If the digits in | |
2845 | .I word | |
2846 | do not specify a file descriptor open for input, a redirection error occurs. | |
2847 | If | |
726f6388 JA |
2848 | .I word |
2849 | evaluates to | |
2850 | .BR \- , | |
2851 | file descriptor | |
2852 | .I n | |
2853 | is closed. If | |
2854 | .I n | |
2855 | is not specified, the standard input (file descriptor 0) is used. | |
2856 | .PP | |
2857 | The operator | |
2858 | .RS | |
2859 | .PP | |
2860 | [\fIn\fP]\fB>&\fP\fIword\fP | |
2861 | .RE | |
2862 | .PP | |
2863 | is used similarly to duplicate output file descriptors. If | |
2864 | .I n | |
2865 | is not specified, the standard output (file descriptor 1) is used. | |
cce855bc JA |
2866 | If the digits in |
2867 | .I word | |
2868 | do not specify a file descriptor open for output, a redirection error occurs. | |
726f6388 JA |
2869 | As a special case, if \fIn\fP is omitted, and \fIword\fP does not |
2870 | expand to one or more digits, the standard output and standard | |
2871 | error are redirected as described previously. | |
2872 | .SS "Opening File Descriptors for Reading and Writing" | |
2873 | .PP | |
2874 | The redirection operator | |
2875 | .RS | |
2876 | .PP | |
2877 | [\fIn\fP]\fB<>\fP\fIword\fP | |
2878 | .RE | |
2879 | .PP | |
2880 | causes the file whose name is the expansion of | |
2881 | .I word | |
2882 | to be opened for both reading and writing on file descriptor | |
2883 | .IR n , | |
ccc6cda3 | 2884 | or on file descriptor 0 if |
726f6388 JA |
2885 | .I n |
2886 | is not specified. If the file does not exist, it is created. | |
726f6388 | 2887 | .SH ALIASES |
bb70624e | 2888 | \fIAliases\fP allow a string to be substituted for a word when it is used |
cce855bc | 2889 | as the first word of a simple command. |
bb70624e | 2890 | The shell maintains a list of aliases that may be set and unset with the |
726f6388 JA |
2891 | .B alias |
2892 | and | |
2893 | .B unalias | |
2894 | builtin commands (see | |
2895 | .SM | |
2896 | .B SHELL BUILTIN COMMANDS | |
2897 | below). | |
2898 | The first word of each command, if unquoted, | |
2899 | is checked to see if it has an | |
2900 | alias. If so, that word is replaced by the text of the alias. | |
2901 | The alias name and the replacement text may contain any valid | |
2902 | shell input, including the | |
2903 | .I metacharacters | |
2904 | listed above, with the exception that the alias name may not | |
2905 | contain \fI=\fP. The first word of the replacement text is tested | |
2906 | for aliases, but a word that is identical to an alias being expanded | |
2907 | is not expanded a second time. This means that one may alias | |
2908 | .B ls | |
2909 | to | |
2910 | .BR "ls \-F" , | |
2911 | for instance, and | |
2912 | .B bash | |
2913 | does not try to recursively expand the replacement text. | |
2914 | If the last character of the alias value is a | |
2915 | .IR blank , | |
2916 | then the next command | |
2917 | word following the alias is also checked for alias expansion. | |
2918 | .PP | |
2919 | Aliases are created and listed with the | |
2920 | .B alias | |
2921 | command, and removed with the | |
2922 | .B unalias | |
2923 | command. | |
2924 | .PP | |
ccc6cda3 | 2925 | There is no mechanism for using arguments in the replacement text. |
bb70624e JA |
2926 | If arguments are needed, a shell function should be used (see |
2927 | .SM | |
2928 | .B FUNCTIONS | |
2929 | below). | |
726f6388 | 2930 | .PP |
ccc6cda3 JA |
2931 | Aliases are not expanded when the shell is not interactive, unless |
2932 | the | |
2933 | .B expand_aliases | |
2934 | shell option is set using | |
2935 | .B shopt | |
2936 | (see the description of | |
2937 | .B shopt | |
2938 | under | |
2939 | .SM | |
2940 | \fBSHELL BUILTIN COMMANDS\fP | |
2941 | below). | |
726f6388 JA |
2942 | .PP |
2943 | The rules concerning the definition and use of aliases are | |
2944 | somewhat confusing. | |
2945 | .B Bash | |
2946 | always reads at least one complete line | |
2947 | of input before executing any | |
2948 | of the commands on that line. Aliases are expanded when a | |
2949 | command is read, not when it is executed. Therefore, an | |
2950 | alias definition appearing on the same line as another | |
2951 | command does not take effect until the next line of input is read. | |
ccc6cda3 | 2952 | The commands following the alias definition |
726f6388 JA |
2953 | on that line are not affected by the new alias. |
2954 | This behavior is also an issue when functions are executed. | |
cce855bc | 2955 | Aliases are expanded when a function definition is read, |
726f6388 JA |
2956 | not when the function is executed, because a function definition |
2957 | is itself a compound command. As a consequence, aliases | |
2958 | defined in a function are not available until after that | |
2959 | function is executed. To be safe, always put | |
2960 | alias definitions on a separate line, and do not use | |
2961 | .B alias | |
2962 | in compound commands. | |
2963 | .PP | |
cce855bc | 2964 | For almost every purpose, aliases are superseded by |
726f6388 | 2965 | shell functions. |
ccc6cda3 JA |
2966 | .SH FUNCTIONS |
2967 | A shell function, defined as described above under | |
2968 | .SM | |
2969 | .BR "SHELL GRAMMAR" , | |
2970 | stores a series of commands for later execution. | |
bb70624e JA |
2971 | When the name of a shell function is used as a simple command name, |
2972 | the list of commands associated with that function name is executed. | |
ccc6cda3 JA |
2973 | Functions are executed in the context of the |
2974 | current shell; no new process is created to interpret | |
2975 | them (contrast this with the execution of a shell script). | |
2976 | When a function is executed, the arguments to the | |
2977 | function become the positional parameters | |
bb70624e JA |
2978 | during its execution. |
2979 | The special parameter | |
ccc6cda3 JA |
2980 | .B # |
2981 | is updated to reflect the change. Positional parameter 0 | |
bb70624e JA |
2982 | is unchanged. |
2983 | The | |
2984 | .SM | |
2985 | .B FUNCNAME | |
2986 | variable is set to the name of the function while the function | |
2987 | is executing. | |
2988 | All other aspects of the shell execution | |
ccc6cda3 JA |
2989 | environment are identical between a function and its caller |
2990 | with the exception that the | |
2991 | .SM | |
2992 | .B DEBUG | |
2993 | trap (see the description of the | |
2994 | .B trap | |
2995 | builtin under | |
2996 | .SM | |
2997 | .B SHELL BUILTIN COMMANDS | |
2998 | below) is not inherited. | |
726f6388 | 2999 | .PP |
ccc6cda3 JA |
3000 | Variables local to the function may be declared with the |
3001 | .B local | |
3002 | builtin command. Ordinarily, variables and their values | |
3003 | are shared between the function and its caller. | |
726f6388 | 3004 | .PP |
ccc6cda3 JA |
3005 | If the builtin command |
3006 | .B return | |
3007 | is executed in a function, the function completes and | |
3008 | execution resumes with the next command after the function | |
3009 | call. When a function completes, the values of the | |
3010 | positional parameters and the special parameter | |
3011 | .B # | |
cce855bc | 3012 | are restored to the values they had prior to the function's |
ccc6cda3 | 3013 | execution. |
726f6388 | 3014 | .PP |
ccc6cda3 JA |
3015 | Function names and definitions may be listed with the |
3016 | .B \-f | |
726f6388 | 3017 | option to the |
ccc6cda3 JA |
3018 | .B declare |
3019 | or | |
3020 | .B typeset | |
3021 | builtin commands. The | |
3022 | .B \-F | |
3023 | option to | |
3024 | .B declare | |
3025 | or | |
3026 | .B typeset | |
3027 | will list the function names only. | |
3028 | Functions may be exported so that subshells | |
3029 | automatically have them defined with the | |
3030 | .B \-f | |
3031 | option to the | |
3032 | .B export | |
3033 | builtin. | |
726f6388 | 3034 | .PP |
ccc6cda3 JA |
3035 | Functions may be recursive. No limit is imposed on the number |
3036 | of recursive calls. | |
cce855bc JA |
3037 | .SH "ARITHMETIC EVALUATION" |
3038 | The shell allows arithmetic expressions to be evaluated, under | |
3039 | certain circumstances (see the \fBlet\fP builtin command and | |
3040 | \fBArithmetic Expansion\fP). | |
3041 | Evaluation is done in long integers with no check for overflow, | |
3042 | though division by 0 is trapped and flagged as an error. | |
bb70624e JA |
3043 | The operators and their precedence and associativity are the same |
3044 | as in the C language. | |
cce855bc JA |
3045 | The following list of operators is grouped into levels of |
3046 | equal-precedence operators. | |
3047 | The levels are listed in order of decreasing precedence. | |
726f6388 | 3048 | .PP |
cce855bc JA |
3049 | .PD 0 |
3050 | .TP | |
bb70624e JA |
3051 | .B \fIid\fP++ \fIid\fP\-\- |
3052 | variable post-increment and post-decrement | |
3053 | .TP | |
3054 | .B ++\fIid\fP \-\-\fIid\fP | |
3055 | variable pre-increment and pre-decrement | |
3056 | .TP | |
cce855bc JA |
3057 | .B \- + |
3058 | unary minus and plus | |
3059 | .TP | |
3060 | .B ! ~ | |
3061 | logical and bitwise negation | |
3062 | .TP | |
3063 | .B ** | |
3064 | exponentiation | |
3065 | .TP | |
3066 | .B * / % | |
3067 | multiplication, division, remainder | |
3068 | .TP | |
3069 | .B + \- | |
3070 | addition, subtraction | |
3071 | .TP | |
3072 | .B << >> | |
3073 | left and right bitwise shifts | |
3074 | .TP | |
3075 | .B <= >= < > | |
3076 | comparison | |
3077 | .TP | |
3078 | .B == != | |
3079 | equality and inequality | |
3080 | .TP | |
3081 | .B & | |
3082 | bitwise AND | |
3083 | .TP | |
3084 | .B ^ | |
3085 | bitwise exclusive OR | |
3086 | .TP | |
3087 | .B | | |
3088 | bitwise OR | |
3089 | .TP | |
3090 | .B && | |
3091 | logical AND | |
3092 | .TP | |
3093 | .B || | |
3094 | logical OR | |
3095 | .TP | |
3096 | .B \fIexpr\fP?\fIexpr\fP:\fIexpr\fP | |
3097 | conditional evaluation | |
3098 | .TP | |
3099 | .B = *= /= %= += \-= <<= >>= &= ^= |= | |
3100 | assignment | |
bb70624e JA |
3101 | .TP |
3102 | .B \fIexpr1\fP , \fIexpr2\fP | |
3103 | comma | |
cce855bc | 3104 | .PD |
ccc6cda3 | 3105 | .PP |
cce855bc | 3106 | Shell variables are allowed as operands; parameter expansion is |
bb70624e JA |
3107 | performed before the expression is evaluated. |
3108 | Within an expression, shell variables may also be referenced by name | |
3109 | without using the parameter expansion syntax. | |
3110 | The value of a variable is evaluated as an arithmetic expression | |
3111 | when it is referenced. | |
3112 | A shell variable need not have its integer attribute | |
cce855bc | 3113 | turned on to be used in an expression. |
ccc6cda3 | 3114 | .PP |
cce855bc JA |
3115 | Constants with a leading 0 are interpreted as octal numbers. |
3116 | A leading 0x or 0X denotes hexadecimal. | |
3117 | Otherwise, numbers take the form [\fIbase#\fP]n, where \fIbase\fP | |
3118 | is a decimal number between 2 and 64 representing the arithmetic | |
3119 | base, and \fIn\fP is a number in that base. | |
bb70624e | 3120 | If \fIbase#\fP is omitted, then base 10 is used. |
cce855bc JA |
3121 | The digits greater than 9 are represented by the lowercase letters, |
3122 | the uppercase letters, _, and @, in that order. | |
3123 | If \fIbase\fP is less than or equal to 36, lowercase and uppercase | |
3124 | letters may be used interchangably to represent numbers between 10 | |
3125 | and 35. | |
ccc6cda3 | 3126 | .PP |
cce855bc JA |
3127 | Operators are evaluated in order of precedence. Sub-expressions in |
3128 | parentheses are evaluated first and may override the precedence | |
3129 | rules above. | |
3130 | .SH "CONDITIONAL EXPRESSIONS" | |
3131 | Conditional expressions are used by the \fB[[\fP compound command and | |
3132 | the \fBtest\fP and \fB[\fP builtin commands to test file attributes | |
3133 | and perform string and arithmetic comparisons. | |
3134 | Expressions are formed from the following unary or binary primaries. | |
3135 | If any \fIfile\fP argument to one of the primaries is of the form | |
bb70624e JA |
3136 | \fI/dev/fd/n\fP, then file descriptor \fIn\fP is checked. |
3137 | If the \fIfile\fP argument to one of the primaries is one of | |
3138 | \fI/dev/stdin\fP, \fI/dev/stdout\fP, or \fI/dev/stderr\fP, file | |
3139 | descriptor 0, 1, or 2, respectively, is checked. | |
cce855bc JA |
3140 | .sp 1 |
3141 | .PD 0 | |
3142 | .TP | |
3143 | .B \-a \fIfile\fP | |
3144 | True if \fIfile\fP exists. | |
3145 | .TP | |
3146 | .B \-b \fIfile\fP | |
3147 | True if \fIfile\fP exists and is a block special file. | |
3148 | .TP | |
3149 | .B \-c \fIfile\fP | |
3150 | True if \fIfile\fP exists and is a character special file. | |
3151 | .TP | |
3152 | .B \-d \fIfile\fP | |
3153 | True if \fIfile\fP exists and is a directory. | |
3154 | .TP | |
3155 | .B \-e \fIfile\fP | |
3156 | True if \fIfile\fP exists. | |
3157 | .TP | |
3158 | .B \-f \fIfile\fP | |
3159 | True if \fIfile\fP exists and is a regular file. | |
3160 | .TP | |
3161 | .B \-g \fIfile\fP | |
3162 | True if \fIfile\fP exists and is set-group-id. | |
3163 | .TP | |
b72432fd JA |
3164 | .B \-h \fIfile\fP |
3165 | True if \fIfile\fP exists and is a symbolic link. | |
3166 | .TP | |
cce855bc JA |
3167 | .B \-k \fIfile\fP |
3168 | True if \fIfile\fP exists and its ``sticky'' bit is set. | |
3169 | .TP | |
3170 | .B \-p \fIfile\fP | |
3171 | True if \fIfile\fP exists and is a named pipe (FIFO). | |
3172 | .TP | |
3173 | .B \-r \fIfile\fP | |
3174 | True if \fIfile\fP exists and is readable. | |
3175 | .TP | |
3176 | .B \-s \fIfile\fP | |
3177 | True if \fIfile\fP exists and has a size greater than zero. | |
3178 | .TP | |
3179 | .B \-t \fIfd\fP | |
3180 | True if file descriptor | |
3181 | .I fd | |
3182 | is open and refers to a terminal. | |
3183 | .TP | |
3184 | .B \-u \fIfile\fP | |
3185 | True if \fIfile\fP exists and its set-user-id bit is set. | |
3186 | .TP | |
3187 | .B \-w \fIfile\fP | |
3188 | True if \fIfile\fP exists and is writable. | |
3189 | .TP | |
3190 | .B \-x \fIfile\fP | |
3191 | True if \fIfile\fP exists and is executable. | |
3192 | .TP | |
3193 | .B \-O \fIfile\fP | |
3194 | True if \fIfile\fP exists and is owned by the effective user id. | |
3195 | .TP | |
3196 | .B \-G \fIfile\fP | |
3197 | True if \fIfile\fP exists and is owned by the effective group id. | |
3198 | .TP | |
3199 | .B \-L \fIfile\fP | |
3200 | True if \fIfile\fP exists and is a symbolic link. | |
3201 | .TP | |
3202 | .B \-S \fIfile\fP | |
3203 | True if \fIfile\fP exists and is a socket. | |
3204 | .TP | |
3205 | .B \-N \fIfile\fP | |
3206 | True if \fIfile\fP exists and has been modified since it was last read. | |
3207 | .TP | |
3208 | \fIfile1\fP \-\fBnt\fP \fIfile2\fP | |
3209 | True if \fIfile1\fP is newer (according to | |
3210 | modification date) than \fIfile2\fP. | |
3211 | .TP | |
3212 | \fIfile1\fP \-\fBot\fP \fIfile2\fP | |
3213 | True if \fIfile1\fP is older than \fIfile2\fP. | |
3214 | .TP | |
3215 | \fIfile1\fP \fB\-ef\fP \fIfile2\fP | |
3216 | True if \fIfile1\fP and \fIfile2\fP have the same device and | |
3217 | inode numbers. | |
3218 | .TP | |
3219 | .B \-o \fIoptname\fP | |
3220 | True if shell option | |
3221 | .I optname | |
3222 | is enabled. | |
3223 | See the list of options under the description of the | |
3224 | .B \-o | |
3225 | option to the | |
3226 | .B set | |
3227 | builtin below. | |
3228 | .TP | |
3229 | .B \-z \fIstring\fP | |
3230 | True if the length of \fIstring\fP is zero. | |
3231 | .TP | |
3232 | .B \-n \fIstring\fP | |
3233 | .TP | |
3234 | \fIstring\fP | |
3235 | True if the length of | |
3236 | .I string | |
3237 | is non-zero. | |
3238 | .TP | |
3239 | \fIstring1\fP \fB==\fP \fIstring2\fP | |
3240 | True if the strings are equal. \fB=\fP may be used in place of | |
3241 | \fB==\fP. | |
3242 | .TP | |
3243 | \fIstring1\fP \fB!=\fP \fIstring2\fP | |
3244 | True if the strings are not equal. | |
3245 | .TP | |
3246 | \fIstring1\fP \fB<\fP \fIstring2\fP | |
3247 | True if \fIstring1\fP sorts before \fIstring2\fP lexicographically | |
3248 | in the current locale. | |
3249 | .TP | |
3250 | \fIstring1\fP \fB>\fP \fIstring2\fP | |
3251 | True if \fIstring1\fP sorts after \fIstring2\fP lexicographically | |
3252 | in the current locale. | |
3253 | .TP | |
3254 | .I \fIarg1\fP \fBOP\fP \fIarg2\fP | |
3255 | .SM | |
3256 | .B OP | |
3257 | is one of | |
3258 | .BR \-eq , | |
3259 | .BR \-ne , | |
3260 | .BR \-lt , | |
3261 | .BR \-le , | |
3262 | .BR \-gt , | |
3263 | or | |
3264 | .BR \-ge . | |
3265 | These arithmetic binary operators return true if \fIarg1\fP | |
3266 | is equal to, not equal to, less than, less than or equal to, | |
3267 | greater than, or greater than or equal to \fIarg2\fP, respectively. | |
3268 | .I Arg1 | |
3269 | and | |
3270 | .I arg2 | |
3271 | may be positive or negative integers. | |
3272 | .PD | |
3273 | .SH "SIMPLE COMMAND EXPANSION" | |
3274 | When a simple command is executed, the shell performs the following | |
3275 | expansions, assignments, and redirections, from left to right. | |
3276 | .IP 1. | |
3277 | The words that the parser has marked as variable assignments (those | |
3278 | preceding the command name) and redirections are saved for later | |
3279 | processing. | |
3280 | .IP 2. | |
3281 | The words that are not variable assignments or redirections are | |
3282 | expanded. If any words remain after expansion, the first word | |
3283 | is taken to be the name of the command and the remaining words are | |
3284 | the arguments. | |
3285 | .IP 3. | |
3286 | Redirections are performed as described above under | |
3287 | .SM | |
3288 | .BR REDIRECTION . | |
3289 | .IP 4. | |
3290 | The text after the \fB=\fP in each variable assignment undergoes tilde | |
3291 | expansion, parameter expansion, command substitution, arithmetic expansion, | |
3292 | and quote removal before being assigned to the variable. | |
3293 | .PP | |
3294 | If no command name results, the variable assignments affect the current | |
3295 | shell environment. Otherwise, the variables are added to the environment | |
3296 | of the executed command and do not affect the current shell environment. | |
3297 | If any of the assignments attempts to assign a value to a readonly variable, | |
3298 | an error occurs, and the command exits with a non-zero status. | |
3299 | .PP | |
3300 | If no command name results, redirections are performed, but do not | |
3301 | affect the current shell environment. A redirection error causes the | |
3302 | command to exit with a non-zero status. | |
3303 | .PP | |
3304 | If there is a command name left after expansion, execution proceeds as | |
3305 | described below. Otherwise, the command exits. If one of the expansions | |
3306 | contained a command substitution, the exit status of the command is | |
3307 | the exit status of the last command substitution performed. If there | |
3308 | were no command substitutions, the command exits with a status of zero. | |
3309 | .SH "COMMAND EXECUTION" | |
3310 | After a command has been split into words, if it results in a | |
3311 | simple command and an optional list of arguments, the following | |
3312 | actions are taken. | |
3313 | .PP | |
3314 | If the command name contains no slashes, the shell attempts to | |
3315 | locate it. If there exists a shell function by that name, that | |
3316 | function is invoked as described above in | |
3317 | .SM | |
3318 | .BR FUNCTIONS . | |
3319 | If the name does not match a function, the shell searches for | |
3320 | it in the list of shell builtins. If a match is found, that | |
3321 | builtin is invoked. | |
3322 | .PP | |
3323 | If the name is neither a shell function nor a builtin, | |
3324 | and contains no slashes, | |
3325 | .B bash | |
3326 | searches each element of the | |
3327 | .SM | |
3328 | .B PATH | |
3329 | for a directory containing an executable file by that name. | |
3330 | .B Bash | |
bb70624e | 3331 | uses a hash table to remember the full pathnames of executable |
cce855bc JA |
3332 | files (see |
3333 | .B hash | |
3334 | under | |
3335 | .SM | |
3336 | .B "SHELL BUILTIN COMMANDS" | |
3337 | below). | |
3338 | A full search of the directories in | |
3339 | .SM | |
3340 | .B PATH | |
3341 | is performed only if the command is not found in the hash table. | |
3342 | If the search is unsuccessful, the shell prints an error | |
3343 | message and returns an exit status of 127. | |
3344 | .PP | |
3345 | If the search is successful, or if the command name contains | |
3346 | one or more slashes, the shell executes the named program in a | |
3347 | separate execution environment. | |
3348 | Argument 0 is set to the name given, and the remaining arguments | |
3349 | to the command are set to the arguments given, if any. | |
3350 | .PP | |
3351 | If this execution fails because the file is not in executable | |
3352 | format, and the file is not a directory, it is assumed to be | |
3353 | a \fIshell script\fP, a file | |
3354 | containing shell commands. A subshell is spawned to execute | |
3355 | it. This subshell reinitializes itself, so | |
3356 | that the effect is as if a new shell had been invoked | |
3357 | to handle the script, with the exception that the locations of | |
3358 | commands remembered by the parent (see | |
3359 | .B hash | |
3360 | below under | |
3361 | .SM | |
3362 | \fBSHELL BUILTIN COMMANDS\fP) | |
3363 | are retained by the child. | |
3364 | .PP | |
3365 | If the program is a file beginning with | |
3366 | .BR #! , | |
3367 | the remainder of the first line specifies an interpreter | |
3368 | for the program. The shell executes the | |
3369 | specified interpreter on operating systems that do not | |
3370 | handle this executable format themselves. The arguments to the | |
3371 | interpreter consist of a single optional argument following the | |
3372 | interpreter name on the first line of the program, followed | |
3373 | by the name of the program, followed by the command | |
3374 | arguments, if any. | |
3375 | .SH COMMAND EXECUTION ENVIRONMENT | |
3376 | The shell has an \fIexecution environment\fP, which consists of the | |
3377 | following: | |
3378 | .sp 1 | |
3379 | .IP \(bu | |
3380 | open files inherited by the shell at invocation, as modified by | |
3381 | redirections supplied to the \fBexec\fP builtin | |
3382 | .IP \(bu | |
3383 | the current working directory as set by \fBcd\fP, \fBpushd\fP, or | |
3384 | \fBpopd\fP, or inherited by the shell at invocation | |
3385 | .IP \(bu | |
3386 | the file creation mode mask as set by \fBumask\fP or inherited from | |
3387 | the shell's parent | |
3388 | .IP \(bu | |
3389 | current traps set by \fBtrap\fP | |
3390 | .IP \(bu | |
3391 | shell parameters that are set by variable assignment or with \fBset\fP | |
3392 | or inherited from the shell's parent in the environment | |
3393 | .IP \(bu | |
3394 | shell functions defined during execution or inherited from the shell's | |
3395 | parent in the environment | |
3396 | .IP \(bu | |
3397 | options enabled at invocation (either by default or with command-line | |
3398 | arguments) or by \fBset\fP | |
3399 | .IP \(bu | |
3400 | options enabled by \fBshopt\fP | |
3401 | .IP \(bu | |
3402 | shell aliases defined with \fBalias\fP | |
3403 | .IP \(bu | |
3404 | various process IDs, including those of background jobs, the value | |
3405 | of \fB$$\fP, and the value of \fB$PPID\fP | |
3406 | .PP | |
3407 | When a simple command other than a builtin or shell function | |
3408 | is to be executed, it | |
3409 | is invoked in a separate execution environment that consists of | |
3410 | the following. Unless otherwise noted, the values are inherited | |
3411 | from the shell. | |
3412 | .sp 1 | |
3413 | .IP \(bu | |
3414 | the shell's open files, plus any modifications and additions specified | |
3415 | by redirections to the command | |
3416 | .IP \(bu | |
3417 | the current working directory | |
3418 | .IP \(bu | |
3419 | the file creation mode mask | |
3420 | .IP \(bu | |
3421 | shell variables marked for export, along with variables exported for | |
3422 | the command, passed in the environment | |
3423 | .IP \(bu | |
3424 | traps caught by the shell are reset to the values the inherited | |
3425 | from the shell's parent, and traps ignored by the shell are ignored | |
3426 | .PP | |
3427 | A command invoked in this separate environment cannot affect the | |
3428 | shell's execution environment. | |
3429 | .PP | |
3430 | Command substitution and asynchronous commands are invoked in a | |
3431 | subshell environment that is a duplicate of the shell environment, | |
3432 | except that traps caught by the shell are reset to the values | |
3433 | that the shell inherited from its parent at invocation. Builtin | |
3434 | commands that are invoked as part of a pipeline are also executed in a | |
3435 | subshell environment. Changes made to the subshell environment | |
3436 | cannot affect the shell's execution environment. | |
3437 | .SH ENVIRONMENT | |
3438 | When a program is invoked it is given an array of strings | |
3439 | called the | |
3440 | .IR environment . | |
3441 | This is a list of | |
3442 | \fIname\fP\-\fIvalue\fP pairs, of the form | |
3443 | .IR "name\fR=\fPvalue" . | |
3444 | .PP | |
bb70624e JA |
3445 | The shell provides several ways to manipulate the environment. |
3446 | On invocation, the shell scans its own environment and | |
cce855bc JA |
3447 | creates a parameter for each name found, automatically marking |
3448 | it for | |
3449 | .I export | |
3450 | to child processes. Executed commands inherit the environment. | |
3451 | The | |
3452 | .B export | |
3453 | and | |
3454 | .B declare \-x | |
3455 | commands allow parameters and functions to be added to and | |
3456 | deleted from the environment. If the value of a parameter | |
3457 | in the environment is modified, the new value becomes part | |
3458 | of the environment, replacing the old. The environment | |
3459 | inherited by any executed command consists of the shell's | |
3460 | initial environment, whose values may be modified in the shell, | |
3461 | less any pairs removed by the | |
3462 | .B unset | |
3463 | command, plus any additions via the | |
3464 | .B export | |
3465 | and | |
3466 | .B declare \-x | |
3467 | commands. | |
3468 | .PP | |
3469 | The environment for any | |
3470 | .I simple command | |
3471 | or function may be augmented temporarily by prefixing it with | |
3472 | parameter assignments, as described above in | |
3473 | .SM | |
3474 | .BR PARAMETERS . | |
3475 | These assignment statements affect only the environment seen | |
3476 | by that command. | |
3477 | .PP | |
3478 | If the | |
3479 | .B \-k | |
3480 | option is set (see the | |
3481 | .B set | |
3482 | builtin command below), then | |
3483 | .I all | |
3484 | parameter assignments are placed in the environment for a command, | |
3485 | not just those that precede the command name. | |
3486 | .PP | |
3487 | When | |
3488 | .B bash | |
3489 | invokes an external command, the variable | |
3490 | .B _ | |
3491 | is set to the full file name of the command and passed to that | |
ccc6cda3 JA |
3492 | command in its environment. |
3493 | .SH "EXIT STATUS" | |
cce855bc | 3494 | For the shell's purposes, a command which exits with a |
ccc6cda3 JA |
3495 | zero exit status has succeeded. An exit status of zero |
3496 | indicates success. A non-zero exit status indicates failure. | |
bb70624e JA |
3497 | When a command terminates on a fatal signal \fIN\fP, \fBbash\fP uses |
3498 | the value of 128+\fIN\fP as the exit status. | |
ccc6cda3 JA |
3499 | .PP |
3500 | If a command is not found, the child process created to | |
3501 | execute it returns a status of 127. If a command is found | |
3502 | but is not executable, the return status is 126. | |
3503 | .PP | |
cce855bc JA |
3504 | If a command fails because of an error during expansion or redirection, |
3505 | the exit status is greater than zero. | |
3506 | .PP | |
ccc6cda3 JA |
3507 | Shell builtin commands return a status of 0 (\fItrue\fP) if |
3508 | successful, and non-zero (\fIfalse\fP) if an error occurs | |
3509 | while they execute. | |
3510 | All builtins return an exit status of 2 to indicate incorrect usage. | |
3511 | .PP | |
3512 | \fBBash\fP itself returns the exit status of the last command | |
3513 | executed, unless a syntax error occurs, in which case it exits | |
3514 | with a non-zero value. See also the \fBexit\fP builtin | |
3515 | command below. | |
3516 | .SH SIGNALS | |
cce855bc | 3517 | When \fBbash\fP is interactive, in the absence of any traps, it ignores |
ccc6cda3 JA |
3518 | .SM |
3519 | .B SIGTERM | |
3520 | (so that \fBkill 0\fP does not kill an interactive shell), | |
3521 | and | |
3522 | .SM | |
3523 | .B SIGINT | |
3524 | is caught and handled (so that the \fBwait\fP builtin is interruptible). | |
3525 | In all cases, \fBbash\fP ignores | |
3526 | .SM | |
3527 | .BR SIGQUIT . | |
3528 | If job control is in effect, | |
3529 | .B bash | |
3530 | ignores | |
3531 | .SM | |
3532 | .BR SIGTTIN , | |
3533 | .SM | |
3534 | .BR SIGTTOU , | |
3535 | and | |
3536 | .SM | |
3537 | .BR SIGTSTP . | |
3538 | .PP | |
cce855bc JA |
3539 | Synchronous jobs started by \fBbash\fP have signal handlers |
3540 | set to the values inherited by the shell from its parent. | |
3541 | When job control is not in effect, asynchronous commands | |
ccc6cda3 JA |
3542 | ignore |
3543 | .SM | |
3544 | .B SIGINT | |
3545 | and | |
3546 | .SM | |
cce855bc JA |
3547 | .B SIGQUIT |
3548 | as well. | |
ccc6cda3 JA |
3549 | Commands run as a result of command substitution ignore the |
3550 | keyboard-generated job control signals | |
3551 | .SM | |
3552 | .BR SIGTTIN , | |
3553 | .SM | |
3554 | .BR SIGTTOU , | |
3555 | and | |
3556 | .SM | |
3557 | .BR SIGTSTP . | |
3558 | .PP | |
3559 | The shell exits by default upon receipt of a | |
3560 | .SM | |
3561 | .BR SIGHUP . | |
3562 | Before exiting, it resends the | |
3563 | .SM | |
3564 | .B SIGHUP | |
cce855bc JA |
3565 | to all jobs, running or stopped. |
3566 | Stopped jobs are sent | |
3567 | .SM | |
3568 | .B SIGCONT | |
3569 | to ensure that they receive the | |
3570 | .SM | |
3571 | .BR SIGHUP . | |
3572 | To prevent the shell from | |
3573 | sending the signal to a particular job, it should be removed from the | |
ccc6cda3 JA |
3574 | jobs table with the |
3575 | .B disown | |
3576 | builtin (see | |
3577 | .SM | |
3578 | .B "SHELL BUILTIN COMMANDS" | |
cce855bc JA |
3579 | below) or marked |
3580 | to not receive | |
ccc6cda3 | 3581 | .SM |
cce855bc JA |
3582 | .B SIGHUP |
3583 | using | |
3584 | .BR "disown \-h" . | |
3585 | .PP | |
3586 | If the | |
3587 | .B huponexit | |
3588 | shell option has been set with | |
3589 | .BR shopt , | |
3590 | .B bash | |
3591 | sends a | |
3592 | .SM | |
3593 | .B SIGHUP | |
3594 | to all jobs when an interactive login shell exits. | |
3595 | .PP | |
3596 | When \fBbash\fP receives a signal for which a trap has been set while | |
3597 | waiting for a command to complete, the trap will not be executed until | |
3598 | the command completes. | |
3599 | When \fBbash\fP is waiting for an asynchronous command via the \fBwait\fP | |
3600 | builtin, the reception of a signal for which a trap has been set will | |
3601 | cause the \fBwait\fP builtin to return immediately with an exit status | |
3602 | greater than 128, immediately after which the trap is executed. | |
ccc6cda3 JA |
3603 | .SH "JOB CONTROL" |
3604 | .I Job control | |
3605 | refers to the ability to selectively stop (\fIsuspend\fP) | |
3606 | the execution of processes and continue (\fIresume\fP) | |
3607 | their execution at a later point. A user typically employs | |
3608 | this facility via an interactive interface supplied jointly | |
3609 | by the system's terminal driver and | |
3610 | .BR bash . | |
3611 | .PP | |
3612 | The shell associates a | |
3613 | .I job | |
3614 | with each pipeline. It keeps a table of currently executing | |
3615 | jobs, which may be listed with the | |
3616 | .B jobs | |
3617 | command. When | |
3618 | .B bash | |
3619 | starts a job asynchronously (in the | |
3620 | .IR background ), | |
3621 | it prints a line that looks like: | |
3622 | .RS | |
3623 | .PP | |
3624 | [1] 25647 | |
3625 | .RE | |
3626 | .PP | |
3627 | indicating that this job is job number 1 and that the process ID | |
3628 | of the last process in the pipeline associated with this job is 25647. | |
3629 | All of the processes in a single pipeline are members of the same job. | |
3630 | .B Bash | |
3631 | uses the | |
3632 | .I job | |
3633 | abstraction as the basis for job control. | |
3634 | .PP | |
3635 | To facilitate the implementation of the user interface to job | |
bb70624e | 3636 | control, the operating system maintains the notion of a \fIcurrent terminal |
ccc6cda3 JA |
3637 | process group ID\fP. Members of this process group (processes whose |
3638 | process group ID is equal to the current terminal process group ID) | |
3639 | receive keyboard-generated signals such as | |
3640 | .SM | |
3641 | .BR SIGINT . | |
3642 | These processes are said to be in the | |
3643 | .IR foreground . | |
3644 | .I Background | |
3645 | processes are those whose process group ID differs from the terminal's; | |
3646 | such processes are immune to keyboard-generated signals. | |
3647 | Only foreground processes are allowed to read from or write to the | |
3648 | terminal. Background processes which attempt to read from (write to) the | |
3649 | terminal are sent a | |
3650 | .SM | |
3651 | .B SIGTTIN (SIGTTOU) | |
3652 | signal by the terminal driver, | |
3653 | which, unless caught, suspends the process. | |
3654 | .PP | |
3655 | If the operating system on which | |
3656 | .B bash | |
3657 | is running supports | |
3658 | job control, | |
3659 | .B bash | |
bb70624e | 3660 | contains facilities to use it. |
ccc6cda3 JA |
3661 | Typing the |
3662 | .I suspend | |
3663 | character (typically | |
3664 | .BR ^Z , | |
3665 | Control-Z) while a process is running | |
bb70624e | 3666 | causes that process to be stopped and returns control to |
ccc6cda3 JA |
3667 | .BR bash . |
3668 | Typing the | |
3669 | .I "delayed suspend" | |
3670 | character (typically | |
3671 | .BR ^Y , | |
3672 | Control-Y) causes the process to be stopped when it | |
3673 | attempts to read input from the terminal, and control to | |
3674 | be returned to | |
3675 | .BR bash . | |
cce855bc | 3676 | The user may then manipulate the state of this job, using the |
ccc6cda3 JA |
3677 | .B bg |
3678 | command to continue it in the background, the | |
3679 | .B fg | |
3680 | command to continue it in the foreground, or | |
3681 | the | |
3682 | .B kill | |
3683 | command to kill it. A \fB^Z\fP takes effect immediately, | |
3684 | and has the additional side effect of causing pending output | |
3685 | and typeahead to be discarded. | |
3686 | .PP | |
3687 | There are a number of ways to refer to a job in the shell. | |
3688 | The character | |
3689 | .B % | |
3690 | introduces a job name. Job number | |
3691 | .I n | |
3692 | may be referred to as | |
3693 | .BR %n . | |
3694 | A job may also be referred to using a prefix of the name used to | |
3695 | start it, or using a substring that appears in its command line. | |
3696 | For example, | |
3697 | .B %ce | |
3698 | refers to a stopped | |
3699 | .B ce | |
3700 | job. If a prefix matches more than one job, | |
3701 | .B bash | |
3702 | reports an error. Using | |
3703 | .BR %?ce , | |
3704 | on the other hand, refers to any job containing the string | |
3705 | .B ce | |
3706 | in its command line. If the substring matches more than one job, | |
3707 | .B bash | |
3708 | reports an error. The symbols | |
3709 | .B %% | |
3710 | and | |
3711 | .B %+ | |
3712 | refer to the shell's notion of the | |
3713 | .IR "current job" , | |
3714 | which is the last job stopped while it was in | |
cce855bc | 3715 | the foreground or started in the background. |
ccc6cda3 JA |
3716 | The |
3717 | .I "previous job" | |
3718 | may be referenced using | |
3719 | .BR %\- . | |
3720 | In output pertaining to jobs (e.g., the output of the | |
3721 | .B jobs | |
3722 | command), the current job is always flagged with a | |
3723 | .BR + , | |
3724 | and the previous job with a | |
3725 | .BR \- . | |
726f6388 | 3726 | .PP |
ccc6cda3 JA |
3727 | Simply naming a job can be used to bring it into the |
3728 | foreground: | |
3729 | .B %1 | |
3730 | is a synonym for | |
3731 | \fB``fg %1''\fP, | |
3732 | bringing job 1 from the background into the foreground. | |
3733 | Similarly, | |
3734 | .B ``%1 &'' | |
3735 | resumes job 1 in the background, equivalent to | |
3736 | \fB``bg %1''\fP. | |
726f6388 | 3737 | .PP |
ccc6cda3 JA |
3738 | The shell learns immediately whenever a job changes state. |
3739 | Normally, | |
3740 | .B bash | |
3741 | waits until it is about to print a prompt before reporting | |
3742 | changes in a job's status so as to not interrupt | |
3743 | any other output. If the | |
3744 | .B \-b | |
3745 | option to the | |
726f6388 | 3746 | .B set |
ccc6cda3 | 3747 | builtin command |
cce855bc | 3748 | is enabled, |
726f6388 | 3749 | .B bash |
ccc6cda3 | 3750 | reports such changes immediately. |
726f6388 | 3751 | .PP |
ccc6cda3 JA |
3752 | If an attempt to exit |
3753 | .B bash | |
3754 | is made while jobs are stopped, the shell prints a warning message. The | |
3755 | .B jobs | |
3756 | command may then be used to inspect their status. | |
3757 | If a second attempt to exit is made without an intervening command, | |
3758 | the shell does not print another warning, and the stopped | |
3759 | jobs are terminated. | |
726f6388 JA |
3760 | .SH PROMPTING |
3761 | When executing interactively, | |
3762 | .B bash | |
3763 | displays the primary prompt | |
3764 | .SM | |
3765 | .B PS1 | |
3766 | when it is ready to read a command, and the secondary prompt | |
3767 | .SM | |
3768 | .B PS2 | |
3769 | when it needs more input to complete a command. | |
3770 | .B Bash | |
3771 | allows these prompt strings to be customized by inserting a number of | |
3772 | backslash-escaped special characters that are decoded as follows: | |
3773 | .RS | |
3774 | .PD 0 | |
3775 | .TP | |
ccc6cda3 JA |
3776 | .B \ea |
3777 | an ASCII bell character (07) | |
726f6388 JA |
3778 | .TP |
3779 | .B \ed | |
3780 | the date in "Weekday Month Date" format (e.g., "Tue May 26") | |
3781 | .TP | |
ccc6cda3 JA |
3782 | .B \ee |
3783 | an ASCII escape character (033) | |
3784 | .TP | |
3785 | .B \eh | |
3786 | the hostname up to the first `.' | |
3787 | .TP | |
3788 | .B \eH | |
3789 | the hostname | |
3790 | .TP | |
bb70624e JA |
3791 | .B \ej |
3792 | the number of jobs currently managed by the shell | |
3793 | .TP | |
3794 | .B \el | |
3795 | the basename of the shell's terminal device name | |
3796 | .TP | |
726f6388 JA |
3797 | .B \en |
3798 | newline | |
3799 | .TP | |
cce855bc JA |
3800 | .B \er |
3801 | carriage return | |
3802 | .TP | |
726f6388 JA |
3803 | .B \es |
3804 | the name of the shell, the basename of | |
3805 | .B $0 | |
3806 | (the portion following the final slash) | |
3807 | .TP | |
ccc6cda3 JA |
3808 | .B \et |
3809 | the current time in 24-hour HH:MM:SS format | |
726f6388 | 3810 | .TP |
ccc6cda3 JA |
3811 | .B \eT |
3812 | the current time in 12-hour HH:MM:SS format | |
3813 | .TP | |
3814 | .B \e@ | |
3815 | the current time in 12-hour am/pm format | |
726f6388 JA |
3816 | .TP |
3817 | .B \eu | |
3818 | the username of the current user | |
3819 | .TP | |
ccc6cda3 JA |
3820 | .B \ev |
3821 | the version of \fBbash\fP (e.g., 2.00) | |
726f6388 | 3822 | .TP |
ccc6cda3 JA |
3823 | .B \eV |
3824 | the release of \fBbash\fP, version + patchlevel (e.g., 2.00.0) | |
3825 | .TP | |
3826 | .B \ew | |
3827 | the current working directory | |
3828 | .TP | |
3829 | .B \eW | |
3830 | the basename of the current working directory | |
726f6388 JA |
3831 | .TP |
3832 | .B \e! | |
3833 | the history number of this command | |
3834 | .TP | |
ccc6cda3 JA |
3835 | .B \e# |
3836 | the command number of this command | |
3837 | .TP | |
726f6388 JA |
3838 | .B \e$ |
3839 | if the effective UID is 0, a | |
3840 | .BR # , | |
3841 | otherwise a | |
3842 | .B $ | |
3843 | .TP | |
ccc6cda3 JA |
3844 | .B \e\fInnn\fP |
3845 | the character corresponding to the octal number \fInnn\fP | |
726f6388 JA |
3846 | .TP |
3847 | .B \e\e | |
3848 | a backslash | |
3849 | .TP | |
3850 | .B \e[ | |
3851 | begin a sequence of non-printing characters, which could be used to | |
3852 | embed a terminal control sequence into the prompt | |
3853 | .TP | |
3854 | .B \e] | |
3855 | end a sequence of non-printing characters | |
3856 | .PD | |
3857 | .RE | |
3858 | .PP | |
3859 | The command number and the history number are usually different: | |
3860 | the history number of a command is its position in the history | |
3861 | list, which may include commands restored from the history file | |
3862 | (see | |
3863 | .SM | |
3864 | .B HISTORY | |
3865 | below), while the command number is the position in the sequence | |
3866 | of commands executed during the current shell session. | |
3867 | After the string is decoded, it is expanded via | |
bb70624e JA |
3868 | parameter expansion, command substitution, arithmetic |
3869 | expansion, and quote removal, subject to the value of the | |
ccc6cda3 JA |
3870 | .B promptvars |
3871 | shell option (see the description of the | |
3872 | .B shopt | |
3873 | command under | |
3874 | .SM | |
3875 | .B "SHELL BUILTIN COMMANDS" | |
3876 | below). | |
726f6388 JA |
3877 | .SH READLINE |
3878 | This is the library that handles reading input when using an interactive | |
3879 | shell, unless the | |
d166f048 | 3880 | .B \-\-noediting |
ccc6cda3 JA |
3881 | option is given at shell invocation. |
3882 | By default, the line editing commands are similar to those of emacs. | |
726f6388 | 3883 | A vi-style line editing interface is also available. |
ccc6cda3 JA |
3884 | To turn off line editing after the shell is running, use the |
3885 | .B +o emacs | |
3886 | or | |
3887 | .B +o vi | |
3888 | options to the | |
3889 | .B set | |
3890 | builtin (see | |
3891 | .SM | |
3892 | .B SHELL BUILTIN COMMANDS | |
3893 | below). | |
3894 | .SS "Readline Notation" | |
726f6388 JA |
3895 | .PP |
3896 | In this section, the emacs-style notation is used to denote | |
3897 | keystrokes. Control keys are denoted by C\-\fIkey\fR, e.g., C\-n | |
3898 | means Control\-N. Similarly, | |
3899 | .I meta | |
3900 | keys are denoted by M\-\fIkey\fR, so M\-x means Meta\-X. (On keyboards | |
3901 | without a | |
3902 | .I meta | |
3903 | key, M\-\fIx\fP means ESC \fIx\fP, i.e., press the Escape key | |
3904 | then the | |
3905 | .I x | |
3906 | key. This makes ESC the \fImeta prefix\fP. | |
3907 | The combination M\-C\-\fIx\fP means ESC\-Control\-\fIx\fP, | |
3908 | or press the Escape key | |
3909 | then hold the Control key while pressing the | |
3910 | .I x | |
3911 | key.) | |
3912 | .PP | |
ccc6cda3 JA |
3913 | Readline commands may be given numeric |
3914 | .IR arguments , | |
3915 | which normally act as a repeat count. | |
3916 | Sometimes, however, it is the sign of the argument that is significant. | |
3917 | Passing a negative argument to a command that acts in the forward | |
3918 | direction (e.g., \fBkill\-line\fP) causes that command to act in a | |
3919 | backward direction. | |
3920 | Commands whose behavior with arguments deviates from this are noted | |
3921 | below. | |
3922 | .PP | |
3923 | When a command is described as \fIkilling\fP text, the text | |
3924 | deleted is saved for possible future retrieval | |
3925 | (\fIyanking\fP). The killed text is saved in a | |
3926 | \fIkill ring\fP. Consecutive kills cause the text to be | |
3927 | accumulated into one unit, which can be yanked all at once. | |
3928 | Commands which do not kill text separate the chunks of text | |
3929 | on the kill ring. | |
3930 | .SS "Readline Initialization" | |
3931 | .PP | |
3932 | Readline is customized by putting commands in an initialization | |
3933 | file (the \fIinputrc\fP file). | |
3934 | The name of this file is taken from the value of the | |
726f6388 | 3935 | .SM |
ccc6cda3 JA |
3936 | .B INPUTRC |
3937 | variable. If that variable is unset, the default is | |
726f6388 | 3938 | .IR ~/.inputrc . |
ccc6cda3 JA |
3939 | When a program which uses the readline library starts up, the |
3940 | initialization file is read, and the key bindings and variables | |
3941 | are set. | |
3942 | There are only a few basic constructs allowed in the | |
3943 | readline initialization file. | |
3944 | Blank lines are ignored. | |
3945 | Lines beginning with a \fB#\fP are comments. | |
3946 | Lines beginning with a \fB$\fP indicate conditional constructs. | |
3947 | Other lines denote key bindings and variable settings. | |
3948 | .PP | |
3949 | The default key-bindings may be changed with an | |
3950 | .I inputrc | |
3951 | file. | |
726f6388 JA |
3952 | Other programs that use this library may add their own commands |
3953 | and bindings. | |
3954 | .PP | |
3955 | For example, placing | |
3956 | .RS | |
3957 | .PP | |
3958 | M\-Control\-u: universal\-argument | |
3959 | .RE | |
3960 | or | |
3961 | .RS | |
3962 | C\-Meta\-u: universal\-argument | |
3963 | .RE | |
3964 | into the | |
ccc6cda3 | 3965 | .I inputrc |
726f6388 JA |
3966 | would make M\-C\-u execute the readline command |
3967 | .IR universal\-argument . | |
3968 | .PP | |
3969 | The following symbolic character names are recognized: | |
3970 | .IR RUBOUT , | |
3971 | .IR DEL , | |
3972 | .IR ESC , | |
3973 | .IR LFD , | |
3974 | .IR NEWLINE , | |
3975 | .IR RET , | |
3976 | .IR RETURN , | |
3977 | .IR SPC , | |
3978 | .IR SPACE , | |
3979 | and | |
3980 | .IR TAB . | |
bb70624e | 3981 | .PP |
726f6388 JA |
3982 | In addition to command names, readline allows keys to be bound |
3983 | to a string that is inserted when the key is pressed (a \fImacro\fP). | |
ccc6cda3 | 3984 | .SS "Readline Key Bindings" |
726f6388 JA |
3985 | .PP |
3986 | The syntax for controlling key bindings in the | |
cce855bc | 3987 | .I inputrc |
726f6388 JA |
3988 | file is simple. All that is required is the name of the |
3989 | command or the text of a macro and a key sequence to which | |
3990 | it should be bound. The name may be specified in one of two ways: | |
ccc6cda3 | 3991 | as a symbolic key name, possibly with \fIMeta\-\fP or \fIControl\-\fP |
726f6388 | 3992 | prefixes, or as a key sequence. |
cce855bc | 3993 | When using the form \fBkeyname\fP:\^\fIfunction\-name\fP or \fImacro\fP, |
726f6388 JA |
3994 | .I keyname |
3995 | is the name of a key spelled out in English. For example: | |
3996 | .sp | |
3997 | .RS | |
3998 | Control-u: universal\-argument | |
3999 | .br | |
4000 | Meta-Rubout: backward-kill-word | |
4001 | .br | |
ccc6cda3 | 4002 | Control-o: "> output" |
726f6388 JA |
4003 | .RE |
4004 | .LP | |
4005 | In the above example, | |
ccc6cda3 | 4006 | .I C\-u |
726f6388 JA |
4007 | is bound to the function |
4008 | .BR universal\-argument , | |
ccc6cda3 | 4009 | .I M\-DEL |
726f6388 JA |
4010 | is bound to the function |
4011 | .BR backward\-kill\-word , | |
4012 | and | |
ccc6cda3 | 4013 | .I C\-o |
726f6388 JA |
4014 | is bound to run the macro |
4015 | expressed on the right hand side (that is, to insert the text | |
ccc6cda3 | 4016 | .I "> output" |
726f6388 JA |
4017 | into the line). |
4018 | .PP | |
cce855bc | 4019 | In the second form, \fB"keyseq"\fP:\^\fIfunction\-name\fP or \fImacro\fP, |
726f6388 JA |
4020 | .B keyseq |
4021 | differs from | |
4022 | .B keyname | |
4023 | above in that strings denoting | |
4024 | an entire key sequence may be specified by placing the sequence | |
4025 | within double quotes. Some GNU Emacs style key escapes can be | |
4026 | used, as in the following example. | |
4027 | .sp | |
4028 | .RS | |
ccc6cda3 | 4029 | "\eC\-u": universal\-argument |
726f6388 | 4030 | .br |
ccc6cda3 | 4031 | "\eC\-x\eC\-r": re\-read\-init\-file |
726f6388 JA |
4032 | .br |
4033 | "\ee[11~": "Function Key 1" | |
4034 | .RE | |
4035 | .PP | |
4036 | In this example, | |
ccc6cda3 | 4037 | .I C\-u |
726f6388 JA |
4038 | is again bound to the function |
4039 | .BR universal\-argument . | |
ccc6cda3 | 4040 | .I "C\-x C\-r" |
726f6388 JA |
4041 | is bound to the function |
4042 | .BR re\-read\-init\-file , | |
4043 | and | |
4044 | .I "ESC [ 1 1 ~" | |
4045 | is bound to insert the text | |
4046 | .BR "Function Key 1" . | |
cce855bc | 4047 | The full set of GNU Emacs style escape sequences is |
726f6388 | 4048 | .RS |
cce855bc | 4049 | .PD 0 |
726f6388 JA |
4050 | .TP |
4051 | .B \eC\- | |
4052 | control prefix | |
4053 | .TP | |
ccc6cda3 | 4054 | .B \eM\- |
726f6388 JA |
4055 | meta prefix |
4056 | .TP | |
4057 | .B \ee | |
4058 | an escape character | |
4059 | .TP | |
4060 | .B \e\e | |
4061 | backslash | |
4062 | .TP | |
4063 | .B \e" | |
4064 | literal " | |
4065 | .TP | |
4066 | .B \e' | |
4067 | literal ' | |
4068 | .RE | |
cce855bc JA |
4069 | .PD |
4070 | .PP | |
4071 | In addition to the GNU Emacs style escape sequences, a second | |
4072 | set of backslash escapes is available: | |
4073 | .RS | |
4074 | .PD 0 | |
4075 | .TP | |
4076 | .B \ea | |
4077 | alert (bell) | |
4078 | .TP | |
4079 | .B \eb | |
4080 | backspace | |
4081 | .TP | |
4082 | .B \ed | |
4083 | delete | |
4084 | .TP | |
4085 | .B \ef | |
4086 | form feed | |
4087 | .TP | |
4088 | .B \en | |
4089 | newline | |
4090 | .TP | |
4091 | .B \er | |
4092 | carriage return | |
4093 | .TP | |
4094 | .B \et | |
4095 | horizontal tab | |
4096 | .TP | |
4097 | .B \ev | |
4098 | vertical tab | |
4099 | .TP | |
4100 | .B \e\fInnn\fP | |
4101 | the character whose ASCII code is the octal value \fInnn\fP | |
4102 | (one to three digits) | |
4103 | .TP | |
4104 | .B \ex\fInnn\fP | |
4105 | the character whose ASCII code is the hexadecimal value \fInnn\fP | |
4106 | (one to three digits) | |
4107 | .RE | |
4108 | .PD | |
726f6388 | 4109 | .PP |
cce855bc JA |
4110 | When entering the text of a macro, single or double quotes must |
4111 | be used to indicate a macro definition. | |
4112 | Unquoted text is assumed to be a function name. | |
4113 | In the macro body, the backslash escapes described above are expanded. | |
4114 | Backslash will quote any other character in the macro text, | |
4115 | including " and '. | |
726f6388 JA |
4116 | .PP |
4117 | .B Bash | |
4118 | allows the current readline key bindings to be displayed or modified | |
4119 | with the | |
4120 | .B bind | |
4121 | builtin command. The editing mode may be switched during interactive | |
4122 | use by using the | |
4123 | .B \-o | |
4124 | option to the | |
4125 | .B set | |
4126 | builtin command (see | |
4127 | .SM | |
4128 | .B SHELL BUILTIN COMMANDS | |
4129 | below). | |
ccc6cda3 | 4130 | .SS "Readline Variables" |
726f6388 JA |
4131 | .PP |
4132 | Readline has variables that can be used to further customize its | |
4133 | behavior. A variable may be set in the | |
4134 | .I inputrc | |
4135 | file with a statement of the form | |
4136 | .RS | |
4137 | .PP | |
4138 | \fBset\fP \fIvariable\-name\fP \fIvalue\fP | |
4139 | .RE | |
4140 | .PP | |
4141 | Except where noted, readline variables can take the values | |
4142 | .B On | |
4143 | or | |
4144 | .BR Off . | |
4145 | The variables and their default values are: | |
4146 | .PP | |
4147 | .PD 0 | |
4148 | .TP | |
726f6388 JA |
4149 | .B bell\-style (audible) |
4150 | Controls what happens when readline wants to ring the terminal bell. | |
4151 | If set to \fBnone\fP, readline never rings the bell. If set to | |
4152 | \fBvisible\fP, readline uses a visible bell if one is available. | |
4153 | If set to \fBaudible\fP, readline attempts to ring the terminal's bell. | |
4154 | .TP | |
4155 | .B comment\-begin (``#'') | |
bb70624e | 4156 | The string that is inserted when the readline |
ccc6cda3 | 4157 | .B insert\-comment |
726f6388 | 4158 | command is executed. |
ccc6cda3 JA |
4159 | This command is bound to |
4160 | .B M\-# | |
4161 | in emacs mode and to | |
4162 | .B # | |
4163 | in vi command mode. | |
726f6388 | 4164 | .TP |
cce855bc JA |
4165 | .B completion\-ignore\-case (Off) |
4166 | If set to \fBOn\fP, readline performs filename matching and completion | |
4167 | in a case\-insensitive fashion. | |
4168 | .TP | |
726f6388 JA |
4169 | .B completion\-query\-items (100) |
4170 | This determines when the user is queried about viewing | |
4171 | the number of possible completions | |
4172 | generated by the \fBpossible\-completions\fP command. | |
4173 | It may be set to any integer value greater than or equal to | |
4174 | zero. If the number of possible completions is greater than | |
4175 | or equal to the value of this variable, the user is asked whether | |
4176 | or not he wishes to view them; otherwise they are simply listed | |
4177 | on the terminal. | |
4178 | .TP | |
ccc6cda3 JA |
4179 | .B convert\-meta (On) |
4180 | If set to \fBOn\fP, readline will convert characters with the | |
4181 | eighth bit set to an ASCII key sequence | |
bb70624e | 4182 | by stripping the eighth bit and prefixing an |
ccc6cda3 JA |
4183 | escape character (in effect, using escape as the \fImeta prefix\fP). |
4184 | .TP | |
4185 | .B disable\-completion (Off) | |
4186 | If set to \fBOn\fP, readline will inhibit word completion. Completion | |
4187 | characters will be inserted into the line as if they had been | |
4188 | mapped to \fBself-insert\fP. | |
4189 | .TP | |
4190 | .B editing\-mode (emacs) | |
4191 | Controls whether readline begins with a set of key bindings similar | |
4192 | to \fIemacs\fP or \fIvi\fP. | |
4193 | .B editing\-mode | |
4194 | can be set to either | |
4195 | .B emacs | |
4196 | or | |
4197 | .BR vi . | |
4198 | .TP | |
4199 | .B enable\-keypad (Off) | |
4200 | When set to \fBOn\fP, readline will try to enable the application | |
4201 | keypad when it is called. Some systems need this to enable the | |
4202 | arrow keys. | |
4203 | .TP | |
4204 | .B expand\-tilde (Off) | |
4205 | If set to \fBon\fP, tilde expansion is performed when readline | |
4206 | attempts word completion. | |
4207 | .TP | |
4208 | .B horizontal\-scroll\-mode (Off) | |
4209 | When set to \fBOn\fP, makes readline use a single line for display, | |
4210 | scrolling the input horizontally on a single screen line when it | |
4211 | becomes longer than the screen width rather than wrapping to a new line. | |
4212 | .TP | |
4213 | .B input\-meta (Off) | |
4214 | If set to \fBOn\fP, readline will enable eight-bit input (that is, | |
4215 | it will not strip the high bit from the characters it reads), | |
4216 | regardless of what the terminal claims it can support. The name | |
4217 | .B meta\-flag | |
4218 | is a synonym for this variable. | |
4219 | .TP | |
b72432fd JA |
4220 | .B isearch\-terminators (``C\-[C\-J'') |
4221 | The string of characters that should terminate an incremental | |
4222 | search without subsequently executing the character as a command. | |
4223 | If this variable has not been given a value, the characters | |
4224 | \fIESC\fP and \fIC\-J\fP will terminate an incremental search. | |
4225 | .TP | |
726f6388 | 4226 | .B keymap (emacs) |
cce855bc | 4227 | Set the current readline keymap. The set of valid keymap names is |
ccc6cda3 JA |
4228 | \fIemacs, emacs\-standard, emacs\-meta, emacs\-ctlx, vi, |
4229 | vi\-command\fP, and | |
4230 | .IR vi\-insert . | |
4231 | \fIvi\fP is equivalent to \fIvi\-command\fP; \fIemacs\fP is | |
4232 | equivalent to \fIemacs\-standard\fP. The default value is | |
726f6388 JA |
4233 | .IR emacs ; |
4234 | the value of | |
4235 | .B editing\-mode | |
4236 | also affects the default keymap. | |
4237 | .TP | |
ccc6cda3 JA |
4238 | .B mark\-directories (On) |
4239 | If set to \fBOn\fP, completed directory names have a slash | |
4240 | appended. | |
4241 | .TP | |
4242 | .B mark\-modified\-lines (Off) | |
4243 | If set to \fBOn\fP, history lines that have been modified are displayed | |
4244 | with a preceding asterisk (\fB*\fP). | |
4245 | .TP | |
4246 | .B output\-meta (Off) | |
4247 | If set to \fBOn\fP, readline will display characters with the | |
4248 | eighth bit set directly rather than as a meta-prefixed escape | |
4249 | sequence. | |
4250 | .TP | |
cce855bc JA |
4251 | .B print\-completions\-horizontally (Off) |
4252 | If set to \fBOn\fP, readline will display completions with matches | |
4253 | sorted horizontally in alphabetical order, rather than down the screen. | |
4254 | .TP | |
726f6388 JA |
4255 | .B show\-all\-if\-ambiguous (Off) |
4256 | This alters the default behavior of the completion functions. If | |
4257 | set to | |
4258 | .BR on , | |
4259 | words which have more than one possible completion cause the | |
4260 | matches to be listed immediately instead of ringing the bell. | |
4261 | .TP | |
ccc6cda3 JA |
4262 | .B visible\-stats (Off) |
4263 | If set to \fBOn\fP, a character denoting a file's type as reported | |
4264 | by \fIstat\fP(2) is appended to the filename when listing possible | |
4265 | completions. | |
726f6388 | 4266 | .PD |
ccc6cda3 | 4267 | .SS "Readline Conditional Constructs" |
726f6388 JA |
4268 | .PP |
4269 | Readline implements a facility similar in spirit to the conditional | |
4270 | compilation features of the C preprocessor which allows key | |
4271 | bindings and variable settings to be performed as the result | |
cce855bc | 4272 | of tests. There are four parser directives used. |
726f6388 JA |
4273 | .IP \fB$if\fP |
4274 | The | |
4275 | .B $if | |
4276 | construct allows bindings to be made based on the | |
4277 | editing mode, the terminal being used, or the application using | |
4278 | readline. The text of the test extends to the end of the line; | |
4279 | no characters are required to isolate it. | |
4280 | .RS | |
4281 | .IP \fBmode\fP | |
4282 | The \fBmode=\fP form of the \fB$if\fP directive is used to test | |
4283 | whether readline is in emacs or vi mode. | |
4284 | This may be used in conjunction | |
4285 | with the \fBset keymap\fP command, for instance, to set bindings in | |
ccc6cda3 | 4286 | the \fIemacs\-standard\fP and \fIemacs\-ctlx\fP keymaps only if |
726f6388 JA |
4287 | readline is starting out in emacs mode. |
4288 | .IP \fBterm\fP | |
4289 | The \fBterm=\fP form may be used to include terminal-specific | |
4290 | key bindings, perhaps to bind the key sequences output by the | |
4291 | terminal's function keys. The word on the right side of the | |
4292 | .B = | |
cce855bc | 4293 | is tested against the both full name of the terminal and the portion |
726f6388 JA |
4294 | of the terminal name before the first \fB\-\fP. This allows |
4295 | .I sun | |
4296 | to match both | |
4297 | .I sun | |
4298 | and | |
4299 | .IR sun\-cmd , | |
4300 | for instance. | |
4301 | .IP \fBapplication\fP | |
4302 | The \fBapplication\fP construct is used to include | |
ccc6cda3 | 4303 | application-specific settings. Each program using the readline |
726f6388 JA |
4304 | library sets the \fIapplication name\fP, and an initialization |
4305 | file can test for a particular value. | |
4306 | This could be used to bind key sequences to functions useful for | |
4307 | a specific program. For instance, the following command adds a | |
4308 | key sequence that quotes the current or previous word in Bash: | |
cce855bc | 4309 | .sp 1 |
726f6388 JA |
4310 | .RS |
4311 | .nf | |
4312 | \fB$if\fP Bash | |
4313 | # Quote the current or previous word | |
ccc6cda3 | 4314 | "\eC\-xq": "\eeb\e"\eef\e"" |
726f6388 JA |
4315 | \fB$endif\fP |
4316 | .fi | |
4317 | .RE | |
4318 | .RE | |
4319 | .IP \fB$endif\fP | |
cce855bc | 4320 | This command, as seen in the previous example, terminates an |
726f6388 JA |
4321 | \fB$if\fP command. |
4322 | .IP \fB$else\fP | |
4323 | Commands in this branch of the \fB$if\fP directive are executed if | |
4324 | the test fails. | |
cce855bc JA |
4325 | .IP \fB$include\fP |
4326 | This directive takes a single filename as an argument and reads commands | |
4327 | and bindings from that file. For example, the following directive | |
4328 | would read \fI/etc/inputrc\fP: | |
4329 | .sp 1 | |
4330 | .RS | |
4331 | .nf | |
4332 | \fB$include\fP \^ \fI/etc/inputrc\fP | |
4333 | .fi | |
4334 | .RE | |
ccc6cda3 | 4335 | .SS Searching |
726f6388 | 4336 | .PP |
ccc6cda3 JA |
4337 | Readline provides commands for searching through the command history |
4338 | (see | |
4339 | .SM | |
4340 | .B HISTORY | |
4341 | below) for lines containing a specified string. | |
4342 | There are two search modes: | |
4343 | .I incremental | |
4344 | and | |
4345 | .IR non-incremental . | |
4346 | .PP | |
4347 | Incremental searches begin before the user has finished typing the | |
4348 | search string. | |
4349 | As each character of the search string is typed, readline displays | |
4350 | the next entry from the history matching the string typed so far. | |
4351 | An incremental search requires only as many characters as needed to | |
4352 | find the desired history entry. | |
bb70624e | 4353 | The characters present in the value of the \fBisearch-terminators\fP |
b72432fd JA |
4354 | variable are used to terminate an incremental search. |
4355 | If that variable has not been assigned a value the Escape and | |
4356 | Control-J characters will terminate an incremental search. | |
ccc6cda3 JA |
4357 | Control-G will abort an incremental search and restore the original |
4358 | line. | |
4359 | When the search is terminated, the history entry containing the | |
4360 | search string becomes the current line. | |
bb70624e | 4361 | .PP |
ccc6cda3 JA |
4362 | To find other matching entries in the history list, type Control-S or |
4363 | Control-R as appropriate. | |
4364 | This will search backward or forward in the history for the next | |
4365 | entry matching the search string typed so far. | |
4366 | Any other key sequence bound to a readline command will terminate | |
4367 | the search and execute that command. | |
4368 | For instance, a \fInewline\fP will terminate the search and accept | |
4369 | the line, thereby executing the command from the history list. | |
4370 | .PP | |
4371 | Non-incremental searches read the entire search string before starting | |
4372 | to search for matching history lines. The search string may be | |
cce855bc | 4373 | typed by the user or be part of the contents of the current line. |
ccc6cda3 | 4374 | .SS "Readline Command Names" |
726f6388 JA |
4375 | .PP |
4376 | The following is a list of the names of the commands and the default | |
4377 | key sequences to which they are bound. | |
ccc6cda3 | 4378 | Command names without an accompanying key sequence are unbound by default. |
bb70624e JA |
4379 | In the following descriptions, \fIpoint\fP refers to the current cursor |
4380 | position, and \fImark\fP refers to a cursor position saved by the | |
4381 | \fBset\-mark\fP command. | |
4382 | The text between the point and mark is referred to as the \fIregion\fP. | |
726f6388 JA |
4383 | .SS Commands for Moving |
4384 | .PP | |
4385 | .PD 0 | |
4386 | .TP | |
4387 | .B beginning\-of\-line (C\-a) | |
4388 | Move to the start of the current line. | |
4389 | .TP | |
4390 | .B end\-of\-line (C\-e) | |
4391 | Move to the end of the line. | |
4392 | .TP | |
4393 | .B forward\-char (C\-f) | |
4394 | Move forward a character. | |
4395 | .TP | |
4396 | .B backward\-char (C\-b) | |
4397 | Move back a character. | |
4398 | .TP | |
4399 | .B forward\-word (M\-f) | |
4400 | Move forward to the end of the next word. Words are composed of | |
4401 | alphanumeric characters (letters and digits). | |
4402 | .TP | |
4403 | .B backward\-word (M\-b) | |
bb70624e | 4404 | Move back to the start of the current or previous word. Words are |
726f6388 JA |
4405 | composed of alphanumeric characters (letters and digits). |
4406 | .TP | |
4407 | .B clear\-screen (C\-l) | |
4408 | Clear the screen leaving the current line at the top of the screen. | |
4409 | With an argument, refresh the current line without clearing the | |
4410 | screen. | |
4411 | .TP | |
4412 | .B redraw\-current\-line | |
ccc6cda3 | 4413 | Refresh the current line. |
726f6388 JA |
4414 | .PD |
4415 | .SS Commands for Manipulating the History | |
4416 | .PP | |
4417 | .PD 0 | |
4418 | .TP | |
4419 | .B accept\-line (Newline, Return) | |
4420 | Accept the line regardless of where the cursor is. If this line is | |
ccc6cda3 | 4421 | non-empty, add it to the history list according to the state of the |
726f6388 JA |
4422 | .SM |
4423 | .B HISTCONTROL | |
4424 | variable. If the line is a modified history | |
4425 | line, then restore the history line to its original state. | |
4426 | .TP | |
4427 | .B previous\-history (C\-p) | |
4428 | Fetch the previous command from the history list, moving back in | |
4429 | the list. | |
4430 | .TP | |
4431 | .B next\-history (C\-n) | |
4432 | Fetch the next command from the history list, moving forward in the | |
4433 | list. | |
4434 | .TP | |
4435 | .B beginning\-of\-history (M\-<) | |
4436 | Move to the first line in the history. | |
4437 | .TP | |
4438 | .B end\-of\-history (M\->) | |
4439 | Move to the end of the input history, i.e., the line currently being | |
4440 | entered. | |
4441 | .TP | |
4442 | .B reverse\-search\-history (C\-r) | |
4443 | Search backward starting at the current line and moving `up' through | |
4444 | the history as necessary. This is an incremental search. | |
4445 | .TP | |
4446 | .B forward\-search\-history (C\-s) | |
4447 | Search forward starting at the current line and moving `down' through | |
4448 | the history as necessary. This is an incremental search. | |
4449 | .TP | |
4450 | .B non\-incremental\-reverse\-search\-history (M\-p) | |
4451 | Search backward through the history starting at the current line | |
ccc6cda3 | 4452 | using a non-incremental search for a string supplied by the user. |
726f6388 JA |
4453 | .TP |
4454 | .B non\-incremental\-forward\-search\-history (M\-n) | |
ccc6cda3 | 4455 | Search forward through the history using a non-incremental search for |
726f6388 JA |
4456 | a string supplied by the user. |
4457 | .TP | |
4458 | .B history\-search\-forward | |
4459 | Search forward through the history for the string of characters | |
bb70624e | 4460 | between the start of the current line and the point. |
ccc6cda3 | 4461 | This is a non-incremental search. |
726f6388 JA |
4462 | .TP |
4463 | .B history\-search\-backward | |
4464 | Search backward through the history for the string of characters | |
ccc6cda3 JA |
4465 | between the start of the current line and the point. |
4466 | This is a non-incremental search. | |
726f6388 JA |
4467 | .TP |
4468 | .B yank\-nth\-arg (M\-C\-y) | |
4469 | Insert the first argument to the previous command (usually | |
4470 | the second word on the previous line) at point (the current | |
4471 | cursor position). With an argument | |
4472 | .IR n , | |
4473 | insert the \fIn\fPth word from the previous command (the words | |
4474 | in the previous command begin with word 0). A negative argument | |
4475 | inserts the \fIn\fPth word from the end of the previous command. | |
4476 | .TP | |
4477 | .B | |
4478 | yank\-last\-arg (M\-.\^, M\-_\^) | |
ccc6cda3 JA |
4479 | Insert the last argument to the previous command (the last word of |
4480 | the previous history entry). With an argument, | |
4481 | behave exactly like \fByank\-nth\-arg\fP. | |
cce855bc JA |
4482 | Successive calls to \fByank\-last\-arg\fP move back through the history |
4483 | list, inserting the last argument of each line in turn. | |
726f6388 JA |
4484 | .TP |
4485 | .B shell\-expand\-line (M\-C\-e) | |
cce855bc | 4486 | Expand the line as the shell does. This |
726f6388 JA |
4487 | performs alias and history expansion as well as all of the shell |
4488 | word expansions. See | |
4489 | .SM | |
4490 | .B HISTORY EXPANSION | |
4491 | below for a description of history expansion. | |
4492 | .TP | |
4493 | .B history\-expand\-line (M\-^) | |
d166f048 JA |
4494 | Perform history expansion on the current line. |
4495 | See | |
726f6388 JA |
4496 | .SM |
4497 | .B HISTORY EXPANSION | |
4498 | below for a description of history expansion. | |
4499 | .TP | |
cce855bc JA |
4500 | .B magic\-space |
4501 | Perform history expansion on the current line and insert a space. | |
4502 | See | |
4503 | .SM | |
4504 | .B HISTORY EXPANSION | |
4505 | below for a description of history expansion. | |
4506 | .TP | |
d166f048 JA |
4507 | .B alias\-expand\-line |
4508 | Perform alias expansion on the current line. | |
4509 | See | |
4510 | .SM | |
4511 | .B ALIASES | |
4512 | above for a description of alias expansion. | |
4513 | .TP | |
4514 | .B history\-and\-alias\-expand\-line | |
4515 | Perform history and alias expansion on the current line. | |
4516 | .TP | |
726f6388 JA |
4517 | .B insert\-last\-argument (M\-.\^, M\-_\^) |
4518 | A synonym for \fByank\-last\-arg\fP. | |
4519 | .TP | |
ccc6cda3 | 4520 | .B operate\-and\-get\-next (C\-o) |
726f6388 JA |
4521 | Accept the current line for execution and fetch the next line |
4522 | relative to the current line from the history for editing. Any | |
4523 | argument is ignored. | |
4524 | .PD | |
4525 | .SS Commands for Changing Text | |
4526 | .PP | |
4527 | .PD 0 | |
4528 | .TP | |
4529 | .B delete\-char (C\-d) | |
4530 | Delete the character under the cursor. If point is at the | |
4531 | beginning of the line, there are no characters in the line, and | |
cce855bc | 4532 | the last character typed was not bound to \fBdelete\-char\fP, |
726f6388 JA |
4533 | then return |
4534 | .SM | |
4535 | .BR EOF . | |
4536 | .TP | |
4537 | .B backward\-delete\-char (Rubout) | |
4538 | Delete the character behind the cursor. When given a numeric argument, | |
ccc6cda3 | 4539 | save the deleted text on the kill ring. |
726f6388 | 4540 | .TP |
b72432fd JA |
4541 | .B forward\-backward\-delete\-char |
4542 | Delete the character under the cursor, unless the cursor is at the | |
4543 | end of the line, in which case the character behind the cursor is | |
4544 | deleted. By default, this is not bound to a key. | |
4545 | .TP | |
726f6388 | 4546 | .B quoted\-insert (C\-q, C\-v) |
cce855bc | 4547 | Add the next character typed to the line verbatim. This is |
726f6388 JA |
4548 | how to insert characters like \fBC\-q\fP, for example. |
4549 | .TP | |
ccc6cda3 | 4550 | .B tab\-insert (C\-v TAB) |
726f6388 JA |
4551 | Insert a tab character. |
4552 | .TP | |
4553 | .B self\-insert (a,\ b,\ A,\ 1,\ !,\ ...) | |
4554 | Insert the character typed. | |
4555 | .TP | |
4556 | .B transpose\-chars (C\-t) | |
4557 | Drag the character before point forward over the character at point. | |
bb70624e JA |
4558 | Point moves forward as well. |
4559 | If point is at the end of the line, then transpose the two characters | |
4560 | before point. | |
4561 | Negative arguments have no effect. | |
726f6388 JA |
4562 | .TP |
4563 | .B transpose\-words (M\-t) | |
bb70624e JA |
4564 | Drag the word before point past the word after point, |
4565 | moving the point over that word as well. | |
726f6388 JA |
4566 | .TP |
4567 | .B upcase\-word (M\-u) | |
4568 | Uppercase the current (or following) word. With a negative argument, | |
cce855bc | 4569 | uppercase the previous word, but do not move point. |
726f6388 JA |
4570 | .TP |
4571 | .B downcase\-word (M\-l) | |
4572 | Lowercase the current (or following) word. With a negative argument, | |
cce855bc | 4573 | lowercase the previous word, but do not move point. |
726f6388 JA |
4574 | .TP |
4575 | .B capitalize\-word (M\-c) | |
4576 | Capitalize the current (or following) word. With a negative argument, | |
cce855bc | 4577 | capitalize the previous word, but do not move point. |
726f6388 JA |
4578 | .PD |
4579 | .SS Killing and Yanking | |
4580 | .PP | |
4581 | .PD 0 | |
4582 | .TP | |
4583 | .B kill\-line (C\-k) | |
bb70624e | 4584 | Kill the text from point to the end of the line. |
726f6388 | 4585 | .TP |
ccc6cda3 | 4586 | .B backward\-kill\-line (C\-x Rubout) |
726f6388 JA |
4587 | Kill backward to the beginning of the line. |
4588 | .TP | |
4589 | .B unix\-line\-discard (C\-u) | |
4590 | Kill backward from point to the beginning of the line. | |
cce855bc | 4591 | The killed text is saved on the kill-ring. |
bb70624e | 4592 | .\" There is no real difference between this and backward-kill-line |
726f6388 JA |
4593 | .TP |
4594 | .B kill\-whole\-line | |
bb70624e | 4595 | Kill all characters on the current line, no matter where point is. |
726f6388 JA |
4596 | .TP |
4597 | .B kill\-word (M\-d) | |
bb70624e JA |
4598 | Kill from point to the end of the current word, or if between |
4599 | words, to the end of the next word. | |
4600 | Word boundaries are the same as those used by \fBforward\-word\fP. | |
726f6388 JA |
4601 | .TP |
4602 | .B backward\-kill\-word (M\-Rubout) | |
bb70624e JA |
4603 | Kill the word behind point. |
4604 | Word boundaries are the same as those used by \fBbackward\-word\fP. | |
726f6388 JA |
4605 | .TP |
4606 | .B unix\-word\-rubout (C\-w) | |
bb70624e | 4607 | Kill the word behind point, using white space as a word boundary. |
ccc6cda3 | 4608 | The word boundaries are different from \fBbackward\-kill\-word\fP. |
bb70624e | 4609 | The killed text is saved on the kill-ring. |
ccc6cda3 JA |
4610 | .TP |
4611 | .B delete\-horizontal\-space (M\-\e) | |
4612 | Delete all spaces and tabs around point. | |
4613 | .TP | |
4614 | .B kill\-region | |
bb70624e | 4615 | Kill the text in the current region. |
ccc6cda3 JA |
4616 | .TP |
4617 | .B copy\-region\-as\-kill | |
4618 | Copy the text in the region to the kill buffer. | |
726f6388 | 4619 | .TP |
ccc6cda3 JA |
4620 | .B copy\-backward\-word |
4621 | Copy the word before point to the kill buffer. | |
cce855bc | 4622 | The word boundaries are the same as \fBbackward\-word\fP. |
ccc6cda3 JA |
4623 | .TP |
4624 | .B copy\-forward\-word | |
4625 | Copy the word following point to the kill buffer. | |
cce855bc | 4626 | The word boundaries are the same as \fBforward\-word\fP. |
726f6388 JA |
4627 | .TP |
4628 | .B yank (C\-y) | |
4629 | Yank the top of the kill ring into the buffer at the cursor. | |
4630 | .TP | |
4631 | .B yank\-pop (M\-y) | |
ccc6cda3 | 4632 | Rotate the kill ring, and yank the new top. Only works following |
726f6388 JA |
4633 | .B yank |
4634 | or | |
4635 | .BR yank\-pop . | |
4636 | .PD | |
4637 | .SS Numeric Arguments | |
4638 | .PP | |
4639 | .PD 0 | |
4640 | .TP | |
4641 | .B digit\-argument (M\-0, M\-1, ..., M\-\-) | |
4642 | Add this digit to the argument already accumulating, or start a new | |
4643 | argument. M\-\- starts a negative argument. | |
4644 | .TP | |
4645 | .B universal\-argument | |
d166f048 JA |
4646 | This is another way to specify an argument. |
4647 | If this command is followed by one or more digits, optionally with a | |
4648 | leading minus sign, those digits define the argument. | |
4649 | If the command is followed by digits, executing | |
4650 | .B universal\-argument | |
4651 | again ends the numeric argument, but is otherwise ignored. | |
4652 | As a special case, if this command is immediately followed by a | |
4653 | character that is neither a digit or minus sign, the argument count | |
4654 | for the next command is multiplied by four. | |
726f6388 | 4655 | The argument count is initially one, so executing this function the |
d166f048 JA |
4656 | first time makes the argument count four, a second time makes the |
4657 | argument count sixteen, and so on. | |
726f6388 JA |
4658 | .PD |
4659 | .SS Completing | |
4660 | .PP | |
4661 | .PD 0 | |
4662 | .TP | |
4663 | .B complete (TAB) | |
4664 | Attempt to perform completion on the text before point. | |
4665 | .B Bash | |
4666 | attempts completion treating the text as a variable (if the | |
4667 | text begins with \fB$\fP), username (if the text begins with | |
4668 | \fB~\fP), hostname (if the text begins with \fB@\fP), or | |
4669 | command (including aliases and functions) in turn. If none | |
4670 | of these produces a match, filename completion is attempted. | |
4671 | .TP | |
ccc6cda3 | 4672 | .B possible\-completions (M\-?) |
726f6388 JA |
4673 | List the possible completions of the text before point. |
4674 | .TP | |
ccc6cda3 | 4675 | .B insert\-completions (M\-*) |
726f6388 JA |
4676 | Insert all completions of the text before point |
4677 | that would have been generated by | |
ccc6cda3 | 4678 | \fBpossible\-completions\fP. |
726f6388 | 4679 | .TP |
cce855bc JA |
4680 | .B menu\-complete |
4681 | Similar to \fBcomplete\fP, but replaces the word to be completed | |
4682 | with a single match from the list of possible completions. | |
4683 | Repeated execution of \fBmenu\-complete\fP steps through the list | |
4684 | of possible completions, inserting each match in turn. | |
4685 | At the end of the list of completions, the bell is rung and the | |
4686 | original text is restored. | |
4687 | An argument of \fIn\fP moves \fIn\fP positions forward in the list | |
4688 | of matches; a negative argument may be used to move backward | |
4689 | through the list. | |
4690 | This command is intended to be bound to \fBTAB\fP, but is unbound | |
4691 | by default. | |
4692 | .TP | |
b72432fd JA |
4693 | .B delete\-char\-or\-list |
4694 | Deletes the character under the cursor if not at the beginning or | |
bb70624e | 4695 | end of the line (like \fBdelete\-char\fP). |
b72432fd | 4696 | If at the end of the line, behaves identically to |
bb70624e | 4697 | \fBpossible\-completions\fP. |
b72432fd JA |
4698 | This command is unbound by default. |
4699 | .TP | |
726f6388 JA |
4700 | .B complete\-filename (M\-/) |
4701 | Attempt filename completion on the text before point. | |
4702 | .TP | |
4703 | .B possible\-filename\-completions (C\-x /) | |
4704 | List the possible completions of the text before point, | |
4705 | treating it as a filename. | |
4706 | .TP | |
4707 | .B complete\-username (M\-~) | |
4708 | Attempt completion on the text before point, treating | |
4709 | it as a username. | |
4710 | .TP | |
4711 | .B possible\-username\-completions (C\-x ~) | |
4712 | List the possible completions of the text before point, | |
4713 | treating it as a username. | |
4714 | .TP | |
4715 | .B complete\-variable (M\-$) | |
4716 | Attempt completion on the text before point, treating | |
4717 | it as a shell variable. | |
4718 | .TP | |
4719 | .B possible\-variable\-completions (C\-x $) | |
4720 | List the possible completions of the text before point, | |
4721 | treating it as a shell variable. | |
4722 | .TP | |
4723 | .B complete\-hostname (M\-@) | |
4724 | Attempt completion on the text before point, treating | |
4725 | it as a hostname. | |
4726 | .TP | |
4727 | .B possible\-hostname\-completions (C\-x @) | |
4728 | List the possible completions of the text before point, | |
4729 | treating it as a hostname. | |
4730 | .TP | |
4731 | .B complete\-command (M\-!) | |
4732 | Attempt completion on the text before point, treating | |
4733 | it as a command name. Command completion attempts to | |
4734 | match the text against aliases, reserved words, shell | |
cce855bc | 4735 | functions, shell builtins, and finally executable filenames, |
726f6388 JA |
4736 | in that order. |
4737 | .TP | |
4738 | .B possible\-command\-completions (C\-x !) | |
4739 | List the possible completions of the text before point, | |
4740 | treating it as a command name. | |
4741 | .TP | |
ccc6cda3 | 4742 | .B dynamic\-complete\-history (M\-TAB) |
726f6388 JA |
4743 | Attempt completion on the text before point, comparing |
4744 | the text against lines from the history list for possible | |
4745 | completion matches. | |
4746 | .TP | |
4747 | .B complete\-into\-braces (M\-{) | |
bb70624e | 4748 | Perform filename completion and insert the list of possible completions |
726f6388 JA |
4749 | enclosed within braces so the list is available to the shell (see |
4750 | .B Brace Expansion | |
4751 | above). | |
4752 | .PD | |
4753 | .SS Keyboard Macros | |
4754 | .PP | |
4755 | .PD 0 | |
4756 | .TP | |
ccc6cda3 | 4757 | .B start\-kbd\-macro (C\-x (\^) |
726f6388 JA |
4758 | Begin saving the characters typed into the current keyboard macro. |
4759 | .TP | |
ccc6cda3 | 4760 | .B end\-kbd\-macro (C\-x )\^) |
726f6388 | 4761 | Stop saving the characters typed into the current keyboard macro |
ccc6cda3 | 4762 | and store the definition. |
726f6388 | 4763 | .TP |
ccc6cda3 | 4764 | .B call\-last\-kbd\-macro (C\-x e) |
726f6388 JA |
4765 | Re-execute the last keyboard macro defined, by making the characters |
4766 | in the macro appear as if typed at the keyboard. | |
4767 | .PD | |
4768 | .SS Miscellaneous | |
4769 | .PP | |
4770 | .PD 0 | |
4771 | .TP | |
4772 | .B re\-read\-init\-file (C\-x C\-r) | |
ccc6cda3 | 4773 | Read in the contents of the \fIinputrc\fP file, and incorporate |
726f6388 JA |
4774 | any bindings or variable assignments found there. |
4775 | .TP | |
4776 | .B abort (C\-g) | |
4777 | Abort the current editing command and | |
4778 | ring the terminal's bell (subject to the setting of | |
4779 | .BR bell\-style ). | |
4780 | .TP | |
ccc6cda3 JA |
4781 | .B do\-uppercase\-version (M\-a, M\-b, M\-\fIx\fP, ...) |
4782 | If the metafied character \fIx\fP is lowercase, run the command | |
4783 | that is bound to the corresponding uppercase character. | |
726f6388 JA |
4784 | .TP |
4785 | .B prefix\-meta (ESC) | |
4786 | Metafy the next character typed. | |
4787 | .SM | |
4788 | .B ESC | |
4789 | .B f | |
4790 | is equivalent to | |
4791 | .BR Meta\-f . | |
4792 | .TP | |
4793 | .B undo (C\-_, C\-x C\-u) | |
4794 | Incremental undo, separately remembered for each line. | |
4795 | .TP | |
4796 | .B revert\-line (M\-r) | |
cce855bc | 4797 | Undo all changes made to this line. This is like executing the |
726f6388 JA |
4798 | .B undo |
4799 | command enough times to return the line to its initial state. | |
4800 | .TP | |
b72432fd | 4801 | .B tilde\-expand (M\-&) |
726f6388 JA |
4802 | Perform tilde expansion on the current word. |
4803 | .TP | |
ccc6cda3 JA |
4804 | .B set\-mark (C\-@, M\-<space>) |
4805 | Set the mark to the current point. If a | |
4806 | numeric argument is supplied, the mark is set to that position. | |
4807 | .TP | |
4808 | .B exchange\-point\-and\-mark (C\-x C\-x) | |
4809 | Swap the point with the mark. The current cursor position is set to | |
4810 | the saved position, and the old cursor position is saved as the mark. | |
4811 | .TP | |
4812 | .B character\-search (C\-]) | |
4813 | A character is read and point is moved to the next occurrence of that | |
4814 | character. A negative count searches for previous occurrences. | |
4815 | .TP | |
4816 | .B character\-search\-backward (M\-C\-]) | |
4817 | A character is read and point is moved to the previous occurrence of that | |
4818 | character. A negative count searches for subsequent occurrences. | |
4819 | .TP | |
4820 | .B insert\-comment (M\-#) | |
bb70624e | 4821 | The value of the readline |
ccc6cda3 JA |
4822 | .B comment\-begin |
4823 | variable is inserted at the beginning of the current line, and the line | |
bb70624e JA |
4824 | is accepted as if a newline had been typed. The default value of |
4825 | \fBcomment\-begin\fP causes this command to make the current line | |
ccc6cda3 JA |
4826 | a shell comment. |
4827 | .TP | |
4828 | .B glob\-expand\-word (C\-x *) | |
4829 | The word before point is treated as a pattern for pathname expansion, | |
4830 | and the list of matching file names is inserted, replacing the word. | |
4831 | .TP | |
4832 | .B glob\-list\-expansions (C\-x g) | |
4833 | The list of expansions that would have been generated by | |
4834 | .B glob\-expand\-word | |
4835 | is displayed, and the line is redrawn. | |
4836 | .TP | |
726f6388 JA |
4837 | .B dump\-functions |
4838 | Print all of the functions and their key bindings to the | |
4839 | readline output stream. If a numeric argument is supplied, | |
4840 | the output is formatted in such a way that it can be made part | |
4841 | of an \fIinputrc\fP file. | |
4842 | .TP | |
ccc6cda3 JA |
4843 | .B dump\-variables |
4844 | Print all of the settable readline variables and their values to the | |
4845 | readline output stream. If a numeric argument is supplied, | |
4846 | the output is formatted in such a way that it can be made part | |
4847 | of an \fIinputrc\fP file. | |
4848 | .TP | |
4849 | .B dump\-macros | |
4850 | Print all of the readline key sequences bound to macros and the | |
4851 | strings they ouput. If a numeric argument is supplied, | |
4852 | the output is formatted in such a way that it can be made part | |
4853 | of an \fIinputrc\fP file. | |
4854 | .TP | |
726f6388 JA |
4855 | .B display\-shell\-version (C\-x C\-v) |
4856 | Display version information about the current instance of | |
4857 | .BR bash . | |
4858 | .PD | |
bb70624e JA |
4859 | .SS Programmable Completion |
4860 | .PP | |
4861 | When word completion is attempted for an argument to a command for | |
4862 | which a completion specification (a \fIcompspec\fP) has been defined | |
4863 | using the \fBcomplete\fP builtin (see | |
4864 | .SM | |
4865 | .B "SHELL BUILTIN COMMANDS" | |
4866 | below), the programmable completion facilities are invoked. | |
4867 | .PP | |
4868 | First, the command name is identified. | |
4869 | If a compspec has been defined for that command, the | |
4870 | compspec is used to generate the list of possible completions for the word. | |
4871 | If the command word is a full pathname, a compspec for the full | |
4872 | pathname is searched for first. | |
4873 | If no compspec is found for the full pathname, an attempt is made to | |
4874 | find a compspec for the portion following the final slash. | |
4875 | .PP | |
4876 | Once a compspec has been found, it is used to generate the list of | |
4877 | matching words. | |
4878 | If a compspec is not found, the default \fBbash\fP completion as | |
4879 | described above under \fBCompleting\fP is performed. | |
4880 | .PP | |
4881 | First, the actions specified by the compspec are used. | |
4882 | Only matches which are prefixed by the word being completed are | |
4883 | returned. | |
4884 | When the | |
4885 | .B \-f | |
4886 | or | |
4887 | .B \-d | |
4888 | option is used for filename or directory name completion, the shell | |
4889 | variable | |
4890 | .SM | |
4891 | .B FIGNORE | |
4892 | is used to filter the matches. | |
4893 | .PP | |
4894 | Any completions specified by a filename expansion pattern to the | |
4895 | \fB\-G\fP option are generated next. | |
4896 | The words generated by the pattern need not match the word | |
4897 | being completed. | |
4898 | The | |
4899 | .SM | |
4900 | .B GLOBIGNORE | |
4901 | shell variable is not used to filter the matches, but the | |
4902 | .SM | |
4903 | .B FIGNORE | |
4904 | variable is used. | |
4905 | .PP | |
4906 | Next, the string specified as the argument to the \fB\-W\fP option | |
4907 | is considered. | |
4908 | The string is first split using the characters in the | |
4909 | .SM | |
4910 | .B IFS | |
4911 | special variable as delimiters. | |
4912 | Shell quoting is honored. | |
4913 | Each word is then expanded using | |
4914 | brace expansion, tilde expansion, parameter and variable expansion, | |
4915 | command substitution, arithmetic expansion, and pathname expansion, | |
4916 | as described above under | |
4917 | .SM | |
4918 | .BR EXPANSION . | |
4919 | The results are split using the rules described above under | |
4920 | \fBWord Splitting\fP. | |
4921 | The results of the expansion are prefix-matched against the word being | |
4922 | completed, and the matching words become the possible completions. | |
4923 | .PP | |
4924 | After these matches have been generated, any shell function or command | |
4925 | specified with the \fB\-F\fP and \fB\-C\fP options is invoked. | |
4926 | When the command or function is invoked, the | |
4927 | .SM | |
4928 | .B COMP_LINE | |
4929 | and | |
4930 | .SM | |
4931 | .B COMP_POINT | |
4932 | variables are assigned values as described above under | |
4933 | \fBShell Variables\fP. | |
4934 | If a shell function is being invoked, the | |
4935 | .SM | |
4936 | .B COMP_WORDS | |
4937 | and | |
4938 | .SM | |
4939 | .B COMP_CWORD | |
4940 | variables are also set. | |
4941 | When the function or command is invoked, the first argument is the | |
4942 | name of the command whose arguments are being completed, the | |
4943 | second argument is the word being completed, and the third argument | |
4944 | is the word preceding the word being completed on the current command line. | |
4945 | No filtering of the generated completions against the word being completed | |
4946 | is performed; the function or command has complete freedom in generating | |
4947 | the matches. | |
4948 | .PP | |
4949 | Any function specified with \fB\-F\fP is invoked first. | |
4950 | The function may use any of the shell facilities, including the | |
4951 | \fBcompgen\fP builtin described below, to generate the matches. | |
4952 | It must put the possible completions in the | |
4953 | .SM | |
4954 | .B COMPREPLY | |
4955 | array variable. | |
4956 | .PP | |
4957 | Next, any command specified with the \fB\-C\fP option is invoked | |
4958 | in an environment equivalent to command substitution. | |
4959 | It should print a list of completions, one per line, to the | |
4960 | standard output. | |
4961 | Backslash may be used to escape a newline, if necessary. | |
4962 | .PP | |
4963 | After all of the possible completions are generated, any filter | |
4964 | specified with the \fB\-X\fP option is applied to the list. | |
4965 | The filter is a pattern as used for pathname expansion; a \fB&\fP | |
4966 | in the pattern is replaced with the text of the word being completed. | |
4967 | A literal \fB&\fP may be escaped with a backslash; the backslash | |
4968 | is removed before attempting a match. | |
4969 | Any completion that matches the pattern will be removed from the list. | |
4970 | A leading \fB!\fP negates the pattern; in this case any completion | |
4971 | not matching the pattern will be removed. | |
4972 | .PP | |
4973 | Finally, any prefix and suffix specified with the \fB\-P\fP and \fB\-S\fP | |
4974 | options are added to each member of the completion list, and the result is | |
4975 | returned to the readline completion code as the list of possible | |
4976 | completions. | |
4977 | .PP | |
4978 | If a compspec is found, whatever it generates is returned to the completion | |
4979 | code as the full set of possible completions. | |
4980 | The default \fBbash\fP completions are not attempted, and the readline | |
4981 | default of filename completion is disabled. | |
726f6388 | 4982 | .SH HISTORY |
ccc6cda3 | 4983 | When the |
d166f048 | 4984 | .B \-o history |
ccc6cda3 JA |
4985 | option to the |
4986 | .B set | |
4987 | builtin is enabled, the shell provides access to the | |
4988 | \fIcommand history\fP, | |
bb70624e JA |
4989 | the list of commands previously typed. |
4990 | The value of the \fBHISTSIZE\fP variable is used as the | |
4991 | number of commands to save in a history list. | |
4992 | The text of the last | |
726f6388 JA |
4993 | .SM |
4994 | .B HISTSIZE | |
bb70624e | 4995 | commands (default 500) is saved. The shell |
726f6388 JA |
4996 | stores each command in the history list prior to parameter and |
4997 | variable expansion (see | |
4998 | .SM | |
4999 | .B EXPANSION | |
5000 | above) but after history expansion is performed, subject to the | |
5001 | values of the shell variables | |
ccc6cda3 JA |
5002 | .SM |
5003 | .B HISTIGNORE | |
726f6388 JA |
5004 | and |
5005 | .SM | |
5006 | .BR HISTCONTROL . | |
bb70624e | 5007 | .PP |
726f6388 JA |
5008 | On startup, the history is initialized from the file named by |
5009 | the variable | |
5010 | .SM | |
5011 | .B HISTFILE | |
5012 | (default \fI~/.bash_history\fP). | |
bb70624e | 5013 | The file named by the value of |
726f6388 JA |
5014 | .SM |
5015 | .B HISTFILE | |
5016 | is truncated, if necessary, to contain no more than | |
bb70624e | 5017 | the number of lines specified by the value of |
726f6388 | 5018 | .SM |
bb70624e | 5019 | .BR HISTFILESIZE . |
ccc6cda3 JA |
5020 | When an interactive shell exits, the last |
5021 | .SM | |
bb70624e | 5022 | .B $HISTSIZE |
ccc6cda3 JA |
5023 | lines are copied from the history list to |
5024 | .SM | |
bb70624e | 5025 | .BR $HISTFILE . |
ccc6cda3 JA |
5026 | If the |
5027 | .B histappend | |
5028 | shell option is enabled | |
5029 | (see the description of | |
5030 | .B shopt | |
5031 | under | |
5032 | .SM | |
5033 | .B "SHELL BUILTIN COMMANDS" | |
5034 | below), the lines are appended to the history file, | |
5035 | otherwise the history file is overwritten. | |
5036 | If | |
5037 | .SM | |
5038 | .B HISTFILE | |
5039 | is unset, or if the history file is unwritable, the history is | |
5040 | not saved. After saving the history, the history file is truncated | |
5041 | to contain no more than | |
5042 | .SM | |
5043 | .B HISTFILESIZE | |
5044 | lines. If | |
5045 | .SM | |
5046 | .B HISTFILESIZE | |
5047 | is not set, no truncation is performed. | |
5048 | .PP | |
726f6388 JA |
5049 | The builtin command |
5050 | .B fc | |
5051 | (see | |
5052 | .SM | |
5053 | .B SHELL BUILTIN COMMANDS | |
5054 | below) may be used to list or edit and re-execute a portion of | |
5055 | the history list. | |
5056 | The | |
5057 | .B history | |
bb70624e | 5058 | builtin may be used to display or modify the history list and |
ccc6cda3 | 5059 | manipulate the history file. |
bb70624e | 5060 | When using command-line editing, search commands |
726f6388 | 5061 | are available in each editing mode that provide access to the |
ccc6cda3 JA |
5062 | history list. |
5063 | .PP | |
5064 | The shell allows control over which commands are saved on the history | |
5065 | list. The | |
726f6388 | 5066 | .SM |
ccc6cda3 JA |
5067 | .B HISTCONTROL |
5068 | and | |
726f6388 | 5069 | .SM |
ccc6cda3 JA |
5070 | .B HISTIGNORE |
5071 | variables may be set to cause the shell to save only a subset of the | |
5072 | commands entered. | |
5073 | The | |
5074 | .B cmdhist | |
5075 | shell option, if enabled, causes the shell to attempt to save each | |
5076 | line of a multi-line command in the same history entry, adding | |
5077 | semicolons where necessary to preserve syntactic correctness. | |
5078 | The | |
5079 | .B lithist | |
5080 | shell option causes the shell to save the command with embedded newlines | |
5081 | instead of semicolons. See the description of the | |
5082 | .B shopt | |
5083 | builtin below under | |
5084 | .SM | |
5085 | .B "SHELL BUILTIN COMMANDS" | |
5086 | for information on setting and unsetting shell options. | |
726f6388 JA |
5087 | .SH "HISTORY EXPANSION" |
5088 | .PP | |
5089 | The shell supports a history expansion feature that | |
5090 | is similar to the history expansion in | |
5091 | .BR csh. | |
5092 | This section describes what syntax features are available. This | |
5093 | feature is enabled by default for interactive shells, and can be | |
5094 | disabled using the | |
5095 | .B \+H | |
5096 | option to the | |
5097 | .B set | |
5098 | builtin command (see | |
5099 | .SM | |
5100 | .B SHELL BUILTIN COMMANDS | |
ccc6cda3 JA |
5101 | below). Non-interactive shells do not perform history expansion |
5102 | by default. | |
5103 | .PP | |
5104 | History expansions introduce words from the history list into | |
5105 | the input stream, making it easy to repeat commands, insert the | |
5106 | arguments to a previous command into the current input line, or | |
5107 | fix errors in previous commands quickly. | |
726f6388 JA |
5108 | .PP |
5109 | History expansion is performed immediately after a complete line | |
5110 | is read, before the shell breaks it into words. | |
ccc6cda3 | 5111 | It takes place in two parts. |
cce855bc | 5112 | The first is to determine which line from the history list |
ccc6cda3 JA |
5113 | to use during substitution. |
5114 | The second is to select portions of that line for inclusion into | |
5115 | the current one. | |
cce855bc | 5116 | The line selected from the history is the \fIevent\fP, |
ccc6cda3 JA |
5117 | and the portions of that line that are acted upon are \fIwords\fP. |
5118 | Various \fImodifiers\fP are available to manipulate the selected words. | |
5119 | The line is broken into words in the same fashion as when reading input, | |
5120 | so that several \fImetacharacter\fP-separated words surrounded by | |
cce855bc | 5121 | quotes are considered one word. |
ccc6cda3 JA |
5122 | History expansions are introduced by the appearance of the |
5123 | history expansion character, which is \^\fB!\fP\^ by default. | |
5124 | Only backslash (\^\fB\e\fP\^) and single quotes can quote | |
5125 | the history expansion character. | |
5126 | .PP | |
5127 | Several shell options settable with the | |
5128 | .B shopt | |
5129 | builtin may be used to tailor the behavior of history expansion. | |
5130 | If the | |
5131 | .B histverify | |
5132 | shell option is enabled (see the description of the | |
5133 | .B shopt | |
5134 | builtin), and | |
5135 | .B readline | |
5136 | is being used, history substitutions are not immediately passed to | |
5137 | the shell parser. | |
5138 | Instead, the expanded line is reloaded into the | |
5139 | .B readline | |
5140 | editing buffer for further modification. | |
5141 | If | |
5142 | .B readline | |
5143 | is being used, and the | |
5144 | .B histreedit | |
5145 | shell option is enabled, a failed history substitution will be reloaded | |
5146 | into the | |
5147 | .B readline | |
5148 | editing buffer for correction. | |
5149 | The | |
5150 | .B \-p | |
5151 | option to the | |
5152 | .B history | |
5153 | builtin command may be used to see what a history expansion will | |
5154 | do before using it. | |
5155 | The | |
5156 | .B \-s | |
5157 | option to the | |
5158 | .B history | |
5159 | builtin may be used to add commands to the end of the history list | |
5160 | without actually executing them, so that they are available for | |
5161 | subsequent recall. | |
726f6388 JA |
5162 | .PP |
5163 | The shell allows control of the various characters used by the | |
5164 | history expansion mechanism (see the description of | |
5165 | .B histchars | |
5166 | above under | |
5167 | .BR "Shell Variables" ). | |
5168 | .SS Event Designators | |
5169 | .PP | |
5170 | An event designator is a reference to a command line entry in the | |
5171 | history list. | |
5172 | .PP | |
5173 | .PD 0 | |
5174 | .TP | |
5175 | .B ! | |
5176 | Start a history substitution, except when followed by a | |
5177 | .BR blank , | |
5178 | newline, = or (. | |
5179 | .TP | |
726f6388 JA |
5180 | .B !\fIn\fR |
5181 | Refer to command line | |
5182 | .IR n . | |
5183 | .TP | |
5184 | .B !\-\fIn\fR | |
5185 | Refer to the current command line minus | |
5186 | .IR n . | |
5187 | .TP | |
ccc6cda3 JA |
5188 | .B !! |
5189 | Refer to the previous command. This is a synonym for `!\-1'. | |
5190 | .TP | |
726f6388 JA |
5191 | .B !\fIstring\fR |
5192 | Refer to the most recent command starting with | |
5193 | .IR string . | |
5194 | .TP | |
5195 | .B !?\fIstring\fR\fB[?]\fR | |
5196 | Refer to the most recent command containing | |
5197 | .IR string . | |
ccc6cda3 JA |
5198 | The trailing \fB?\fP may be omitted if |
5199 | .I string | |
5200 | is followed immediately by a newline. | |
726f6388 JA |
5201 | .TP |
5202 | .B \d\s+2^\s-2\u\fIstring1\fP\d\s+2^\s-2\u\fIstring2\fP\d\s+2^\s-2\u | |
5203 | Quick substitution. Repeat the last command, replacing | |
5204 | .I string1 | |
5205 | with | |
5206 | .IR string2 . | |
5207 | Equivalent to | |
5208 | ``!!:s/\fIstring1\fP/\fIstring2\fP/'' | |
5209 | (see \fBModifiers\fP below). | |
5210 | .TP | |
5211 | .B !# | |
5212 | The entire command line typed so far. | |
5213 | .PD | |
5214 | .SS Word Designators | |
5215 | .PP | |
ccc6cda3 | 5216 | Word designators are used to select desired words from the event. |
726f6388 JA |
5217 | A |
5218 | .B : | |
ccc6cda3 | 5219 | separates the event specification from the word designator. |
cce855bc | 5220 | It may be omitted if the word designator begins with a |
726f6388 JA |
5221 | .BR ^ , |
5222 | .BR $ , | |
5223 | .BR * , | |
ccc6cda3 | 5224 | .BR \- , |
726f6388 JA |
5225 | or |
5226 | .BR % . | |
5227 | Words are numbered from the beginning of the line, | |
ccc6cda3 JA |
5228 | with the first word being denoted by 0 (zero). |
5229 | Words are inserted into the current line separated by single spaces. | |
726f6388 JA |
5230 | .PP |
5231 | .PD 0 | |
5232 | .TP | |
5233 | .B 0 (zero) | |
5234 | The zeroth word. For the shell, this is the command | |
5235 | word. | |
5236 | .TP | |
5237 | .I n | |
5238 | The \fIn\fRth word. | |
5239 | .TP | |
5240 | .B ^ | |
5241 | The first argument. That is, word 1. | |
5242 | .TP | |
5243 | .B $ | |
5244 | The last argument. | |
5245 | .TP | |
5246 | .B % | |
5247 | The word matched by the most recent `?\fIstring\fR?' search. | |
5248 | .TP | |
5249 | .I x\fB\-\fPy | |
5250 | A range of words; `\-\fIy\fR' abbreviates `0\-\fIy\fR'. | |
5251 | .TP | |
5252 | .B * | |
5253 | All of the words but the zeroth. This is a synonym | |
5254 | for `\fI1\-$\fP'. It is not an error to use | |
5255 | .B * | |
5256 | if there is just one | |
5257 | word in the event; the empty string is returned in that case. | |
5258 | .TP | |
5259 | .B x* | |
5260 | Abbreviates \fIx\-$\fP. | |
5261 | .TP | |
5262 | .B x\- | |
5263 | Abbreviates \fIx\-$\fP like \fBx*\fP, but omits the last word. | |
5264 | .PD | |
ccc6cda3 JA |
5265 | .PP |
5266 | If a word designator is supplied without an event specification, the | |
5267 | previous command is used as the event. | |
726f6388 JA |
5268 | .SS Modifiers |
5269 | .PP | |
ccc6cda3 JA |
5270 | After the optional word designator, there may appear a sequence of |
5271 | one or more of the following modifiers, each preceded by a `:'. | |
726f6388 JA |
5272 | .PP |
5273 | .PD 0 | |
5274 | .PP | |
5275 | .TP | |
5276 | .B h | |
ccc6cda3 JA |
5277 | Remove a trailing file name component, leaving only the head. |
5278 | .TP | |
5279 | .B t | |
5280 | Remove all leading file name components, leaving the tail. | |
726f6388 JA |
5281 | .TP |
5282 | .B r | |
5283 | Remove a trailing suffix of the form \fI.xxx\fP, leaving the | |
5284 | basename. | |
5285 | .TP | |
5286 | .B e | |
5287 | Remove all but the trailing suffix. | |
5288 | .TP | |
726f6388 JA |
5289 | .B p |
5290 | Print the new command but do not execute it. | |
5291 | .TP | |
5292 | .B q | |
5293 | Quote the substituted words, escaping further substitutions. | |
5294 | .TP | |
cce855bc JA |
5295 | .B x |
5296 | Quote the substituted words as with | |
5297 | .BR q , | |
5298 | but break into words at | |
5299 | .B blanks | |
5300 | and newlines. | |
726f6388 | 5301 | .TP |
cce855bc JA |
5302 | .B s/\fIold\fP/\fInew\fP/ |
5303 | Substitute | |
5304 | .I new | |
5305 | for the first occurrence of | |
5306 | .I old | |
5307 | in the event line. Any delimiter can be used in place of /. The | |
5308 | final delimiter is optional if it is the last character of the | |
5309 | event line. The delimiter may be quoted in | |
5310 | .I old | |
5311 | and | |
5312 | .I new | |
5313 | with a single backslash. If & appears in | |
5314 | .IR new , | |
5315 | it is replaced by | |
5316 | .IR old . | |
5317 | A single backslash will quote the &. If | |
5318 | .I old | |
5319 | is null, it is set to the last | |
5320 | .I old | |
5321 | substituted, or, if no previous history substitutions took place, | |
5322 | the last | |
5323 | .I string | |
5324 | in a | |
5325 | .B !?\fIstring\fR\fB[?]\fR | |
5326 | search. | |
ccc6cda3 | 5327 | .TP |
cce855bc JA |
5328 | .B & |
5329 | Repeat the previous substitution. | |
5330 | .TP | |
5331 | .B g | |
5332 | Cause changes to be applied over the entire event line. This is | |
5333 | used in conjunction with `\fB:s\fP' (e.g., `\fB:gs/\fIold\fP/\fInew\fP/\fR') | |
5334 | or `\fB:&\fP'. If used with | |
5335 | `\fB:s\fP', any delimiter can be used | |
5336 | in place of /, and the final delimiter is optional | |
5337 | if it is the last character of the event line. | |
726f6388 | 5338 | .PD |
726f6388 JA |
5339 | .SH "SHELL BUILTIN COMMANDS" |
5340 | .\" start of bash_builtins | |
5341 | .zZ | |
ccc6cda3 JA |
5342 | .PP |
5343 | Unless otherwise noted, each builtin command documented in this | |
5344 | section as accepting options preceded by | |
5345 | .B \- | |
5346 | accepts | |
5347 | .B \-\- | |
5348 | to signify the end of the options. | |
5349 | .sp .5 | |
726f6388 JA |
5350 | .PD 0 |
5351 | .TP | |
5352 | \fB:\fP [\fIarguments\fP] | |
5353 | .PD | |
5354 | No effect; the command does nothing beyond expanding | |
5355 | .I arguments | |
5356 | and performing any specified | |
5357 | redirections. A zero exit code is returned. | |
5358 | .TP | |
5359 | .PD 0 | |
5360 | \fB .\| \fP \fIfilename\fP [\fIarguments\fP] | |
5361 | .TP | |
5362 | \fBsource\fP \fIfilename\fP [\fIarguments\fP] | |
5363 | .PD | |
5364 | Read and execute commands from | |
5365 | .I filename | |
5366 | in the current | |
5367 | shell environment and return the exit status of the last command | |
5368 | executed from | |
5369 | .IR filename . | |
5370 | If | |
5371 | .I filename | |
ccc6cda3 | 5372 | does not contain a slash, file names in |
726f6388 JA |
5373 | .SM |
5374 | .B PATH | |
5375 | are used to find the directory containing | |
5376 | .IR filename . | |
5377 | The file searched for in | |
5378 | .SM | |
5379 | .B PATH | |
5380 | need not be executable. The current directory is | |
5381 | searched if no file is found in | |
5382 | .SM | |
5383 | .BR PATH . | |
ccc6cda3 JA |
5384 | If the |
5385 | .B sourcepath | |
5386 | option to the | |
5387 | .B shopt | |
5388 | builtin command is turned off, the | |
5389 | .SM | |
5390 | .B PATH | |
5391 | is not searched. | |
726f6388 | 5392 | If any \fIarguments\fP are supplied, they become the positional |
ccc6cda3 | 5393 | parameters when \fIfilename\fP is executed. Otherwise the positional |
726f6388 JA |
5394 | parameters are unchanged. |
5395 | The return status is the status of the last command exited within | |
5396 | the script (0 if no commands are executed), and false if | |
5397 | .I filename | |
cce855bc | 5398 | is not found or cannot be read. |
726f6388 | 5399 | .TP |
ccc6cda3 JA |
5400 | \fBalias\fP [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP] ...] |
5401 | \fBAlias\fP with no arguments or with the | |
5402 | .B \-p | |
5403 | option prints the list of aliases in the form | |
5404 | \fBalias\fP \fIname\fP=\fIvalue\fP on standard output. | |
5405 | When arguments are supplied, an alias is defined for | |
5406 | each \fIname\fP whose \fIvalue\fP is given. | |
5407 | A trailing space in \fIvalue\fP causes the next word to be | |
5408 | checked for alias substitution when the alias is expanded. | |
5409 | For each \fIname\fP in the argument list for which no \fIvalue\fP | |
5410 | is supplied, the name and value of the alias is printed. | |
5411 | \fBAlias\fP returns true unless a \fIname\fP is given for which | |
5412 | no alias has been defined. | |
726f6388 JA |
5413 | .TP |
5414 | \fBbg\fP [\fIjobspec\fP] | |
cce855bc JA |
5415 | Resume the suspended job \fIjobspec\fP in the background, as if it |
5416 | had been started with | |
726f6388 JA |
5417 | .BR & . |
5418 | If \fIjobspec\fP is not present, the shell's notion of the | |
5419 | \fIcurrent job\fP is used. | |
5420 | .B bg | |
5421 | .I jobspec | |
5422 | returns 0 unless run when job control is disabled or, when run with | |
5423 | job control enabled, if \fIjobspec\fP was not found or started without | |
5424 | job control. | |
5425 | .TP | |
5426 | .PD 0 | |
cce855bc JA |
5427 | \fBbind\fP [\fB\-m\fP \fIkeymap\fP] [\fB\-lpsvPSV\fP] |
5428 | .TP | |
5429 | \fBbind\fP [\fB\-m\fP \fIkeymap\fP] [\fB\-q\fP \fIfunction\fP] [\fB\-u\fP \fIfunction\fP] [\fB\-r\fP \fIkeyseq\fP] | |
726f6388 | 5430 | .TP |
ccc6cda3 | 5431 | \fBbind\fP [\fB\-m\fP \fIkeymap\fP] \fB\-f\fP \fIfilename\fP |
726f6388 | 5432 | .TP |
bb70624e JA |
5433 | \fBbind\fP [\fB\-m\fP \fIkeymap\fP] \fB\-x\fP \fIkeyseq\fP:\fIshell\-command\fP |
5434 | .TP | |
ccc6cda3 | 5435 | \fBbind\fP [\fB\-m\fP \fIkeymap\fP] \fIkeyseq\fP:\fIfunction\-name\fP |
726f6388 JA |
5436 | .PD |
5437 | Display current | |
5438 | .B readline | |
5439 | key and function bindings, or bind a key sequence to a | |
5440 | .B readline | |
5441 | function or macro. The binding syntax accepted is identical to that of | |
5442 | .IR .inputrc , | |
5443 | but each binding must be passed as a separate argument; | |
ccc6cda3 | 5444 | e.g., '"\eC\-x\eC\-r": re\-read\-init\-file'. Options, if supplied, have the |
726f6388 JA |
5445 | following meanings: |
5446 | .RS | |
5447 | .PD 0 | |
5448 | .TP | |
5449 | .B \-m \fIkeymap\fP | |
5450 | Use | |
5451 | .I keymap | |
5452 | as the keymap to be affected by the subsequent bindings. | |
5453 | Acceptable | |
5454 | .I keymap | |
5455 | names are | |
ccc6cda3 JA |
5456 | \fIemacs, emacs\-standard, emacs\-meta, emacs\-ctlx, vi, |
5457 | vi\-command\fP, and | |
5458 | .IR vi\-insert . | |
5459 | \fIvi\fP is equivalent to \fIvi\-command\fP; \fIemacs\fP is | |
5460 | equivalent to \fIemacs\-standard\fP. | |
726f6388 JA |
5461 | .TP |
5462 | .B \-l | |
ccc6cda3 JA |
5463 | List the names of all \fBreadline\fP functions. |
5464 | .TP | |
5465 | .B \-p | |
5466 | Display \fBreadline\fP function names and bindings in such a way | |
5467 | that they can be re-read. | |
5468 | .TP | |
5469 | .B \-P | |
5470 | List current \fBreadline\fP function names and bindings. | |
726f6388 JA |
5471 | .TP |
5472 | .B \-v | |
ccc6cda3 JA |
5473 | Display \fBreadline\fP variable names and values in such a way that they |
5474 | can be re-read. | |
726f6388 | 5475 | .TP |
ccc6cda3 JA |
5476 | .B \-V |
5477 | List current \fBreadline\fP variable names and values. | |
5478 | .TP | |
5479 | .B \-s | |
5480 | Display \fBreadline\fP key sequences bound to macros and the strings | |
5481 | they output in such a way that they can be re-read. | |
5482 | .TP | |
5483 | .B \-S | |
5484 | Display \fBreadline\fP key sequences bound to macros and the strings | |
5485 | they output. | |
726f6388 JA |
5486 | .TP |
5487 | .B \-f \fIfilename\fP | |
ccc6cda3 | 5488 | Read key bindings from \fIfilename\fP. |
726f6388 JA |
5489 | .TP |
5490 | .B \-q \fIfunction\fP | |
ccc6cda3 JA |
5491 | Query about which keys invoke the named \fIfunction\fP. |
5492 | .TP | |
cce855bc JA |
5493 | .B \-u \fIfunction\fP |
5494 | Unbind all keys bound to the named \fIfunction\fP. | |
5495 | .TP | |
ccc6cda3 JA |
5496 | .B \-r \fIkeyseq\fP |
5497 | Remove any current binding for \fIkeyseq\fP. | |
bb70624e JA |
5498 | .TP |
5499 | .B \-x \fIkeyseq\fP:\fIshell\-command\fP | |
5500 | Cause \fIshell\-command\fP to be executed whenever \fIkeyseq\fP is | |
5501 | entered. | |
726f6388 JA |
5502 | .PD |
5503 | .PP | |
5504 | The return value is 0 unless an unrecognized option is given or an | |
5505 | error occurred. | |
5506 | .RE | |
5507 | .TP | |
5508 | \fBbreak\fP [\fIn\fP] | |
5509 | Exit from within a | |
5510 | .BR for , | |
5511 | .BR while , | |
ccc6cda3 | 5512 | .BR until , |
726f6388 | 5513 | or |
ccc6cda3 | 5514 | .B select |
726f6388 JA |
5515 | loop. If \fIn\fP is specified, break \fIn\fP levels. |
5516 | .I n | |
5517 | must be \(>= 1. If | |
5518 | .I n | |
5519 | is greater than the number of enclosing loops, all enclosing loops | |
5520 | are exited. The return value is 0 unless the shell is not executing | |
5521 | a loop when | |
5522 | .B break | |
5523 | is executed. | |
5524 | .TP | |
5525 | \fBbuiltin\fP \fIshell\-builtin\fP [\fIarguments\fP] | |
5526 | Execute the specified shell builtin, passing it | |
5527 | .IR arguments , | |
5528 | and return its exit status. | |
cce855bc | 5529 | This is useful when defining a |
726f6388 | 5530 | function whose name is the same as a shell builtin, |
cce855bc JA |
5531 | retaining the functionality of the builtin within the function. |
5532 | The \fBcd\fP builtin is commonly redefined this way. | |
5533 | The return status is false if | |
726f6388 JA |
5534 | .I shell\-builtin |
5535 | is not a shell builtin command. | |
5536 | .TP | |
ccc6cda3 | 5537 | \fBcd\fP [\fB\-LP\fP] [\fIdir\fP] |
726f6388 JA |
5538 | Change the current directory to \fIdir\fP. The variable |
5539 | .SM | |
5540 | .B HOME | |
5541 | is the | |
5542 | default | |
5543 | .IR dir . | |
5544 | The variable | |
5545 | .SM | |
5546 | .B CDPATH | |
ccc6cda3 | 5547 | defines the search path for the directory containing |
726f6388 | 5548 | .IR dir . |
ccc6cda3 JA |
5549 | Alternative directory names in |
5550 | .SM | |
5551 | .B CDPATH | |
5552 | are separated by a colon (:). A null directory name in | |
726f6388 JA |
5553 | .SM |
5554 | .B CDPATH | |
ccc6cda3 | 5555 | is the same as the current directory, i.e., ``\fB.\fP''. If |
726f6388 JA |
5556 | .I dir |
5557 | begins with a slash (/), | |
5558 | then | |
5559 | .SM | |
5560 | .B CDPATH | |
ccc6cda3 JA |
5561 | is not used. The |
5562 | .B \-P | |
5563 | option says to use the physical directory structure instead of | |
5564 | following symbolic links (see also the | |
5565 | .B \-P | |
5566 | option to the | |
5567 | .B set | |
5568 | builtin command); the | |
5569 | .B \-L | |
5570 | option forces symbolic links to be followed. An argument of | |
726f6388 JA |
5571 | .B \- |
5572 | is equivalent to | |
5573 | .SM | |
5574 | .BR $OLDPWD . | |
5575 | The return value is true if the directory was successfully changed; | |
5576 | false otherwise. | |
5577 | .TP | |
ccc6cda3 | 5578 | \fBcommand\fP [\fB\-pVv\fP] \fIcommand\fP [\fIarg\fP ...] |
726f6388 JA |
5579 | Run |
5580 | .I command | |
5581 | with | |
5582 | .I args | |
5583 | suppressing the normal shell function lookup. Only builtin | |
5584 | commands or commands found in the | |
5585 | .SM | |
5586 | .B PATH | |
5587 | are executed. If the | |
5588 | .B \-p | |
5589 | option is given, the search for | |
5590 | .I command | |
5591 | is performed using a default value for | |
5592 | .B PATH | |
5593 | that is guaranteed to find all of the standard utilities. | |
5594 | If either the | |
5595 | .B \-V | |
5596 | or | |
5597 | .B \-v | |
5598 | option is supplied, a description of | |
5599 | .I command | |
5600 | is printed. The | |
5601 | .B \-v | |
ccc6cda3 | 5602 | option causes a single word indicating the command or file name |
726f6388 JA |
5603 | used to invoke |
5604 | .I command | |
cce855bc | 5605 | to be displayed; the |
726f6388 JA |
5606 | .B \-V |
5607 | option produces a more verbose description. | |
726f6388 JA |
5608 | If the |
5609 | .B \-V | |
5610 | or | |
5611 | .B \-v | |
5612 | option is supplied, the exit status is 0 if | |
5613 | .I command | |
5614 | was found, and 1 if not. If neither option is supplied and | |
5615 | an error occurred or | |
5616 | .I command | |
5617 | cannot be found, the exit status is 127. Otherwise, the exit status of the | |
5618 | .B command | |
5619 | builtin is the exit status of | |
5620 | .IR command . | |
5621 | .TP | |
bb70624e JA |
5622 | \fBcompgen\fP [\fIoption\fP] [\fIword\fP] |
5623 | Generate possible completion matches for \fIword\fP according to | |
5624 | the \fIoption\fPs, which may be any option accepted by the | |
5625 | .B complete | |
5626 | builtin with the exception of \fB\-p\fP and \fB\-r\fP, and write | |
5627 | the matches to the standard output. | |
5628 | When using the \fB\-F\fP or \fB\-C\fP options, the various shell variables | |
5629 | set by the programmable completion facilities, while available, will not | |
5630 | have useful values. | |
5631 | .sp 1 | |
5632 | The matches will be generated in the same way as if the programmable | |
5633 | completion code had generated them directly from a completion specification | |
5634 | with the same flags. | |
5635 | If \fIword\fP is specified, only those completions matching \fIword\fP | |
5636 | will be displayed. | |
5637 | .sp 1 | |
5638 | The return value is true unless an invalid option is supplied, or no | |
5639 | matches were generated. | |
5640 | .TP | |
5641 | .PD 0 | |
5642 | \fBcomplete\fP [\fB\-abcdefjkvu\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] | |
5643 | .br | |
5644 | [\fB\-X\fP \fIfilterpat\fP] [\fB\-F\fP \fIfunction\fP] [\fB\-C\fP \fIcommand\fP] \fIname\fP [\fIname ...\fP] | |
5645 | .TP | |
5646 | \fBcomplete\fP \fB\-pr\fP [\fIname\fP ...] | |
5647 | .PD | |
5648 | Specify how arguments to each \fIname\fP should be completed. | |
5649 | If the \fB\-p\fP option is supplied, or if no options are supplied, | |
5650 | existing completion specifications are printed in a way that allows | |
5651 | them to be reused as input. | |
5652 | The \fB\-r\fP option removes a completion specification for | |
5653 | each \fIname\fP, or, if no \fIname\fPs are supplied, all | |
5654 | completion specifications. | |
5655 | .sp 1 | |
5656 | The process of applying these completion specifications when word completion | |
5657 | is attempted is described above under \fBProgrammable Completion\fP. | |
5658 | .sp 1 | |
5659 | Other options, if specified, have the following meanings. | |
5660 | The arguments to the \fB\-G\fP, \fB\-W\fP, and \fB\-X\fP options | |
5661 | (and, if necessary, the \fB\-P\fP and \fB\-S\fP options) | |
5662 | should be quoted to protect them from expansion before the | |
5663 | .B complete | |
5664 | builtin is invoked. | |
5665 | .RS | |
5666 | .PD 0 | |
5667 | .TP 8 | |
5668 | \fB\-A\fP \fIaction\fP | |
5669 | The \fIaction\fP may be one of the following to generate a list of possible | |
5670 | completions: | |
5671 | .RS | |
5672 | .TP 8 | |
5673 | .B alias | |
5674 | Alias names. May also be specified as \fB\-a\fP. | |
5675 | .TP 8 | |
5676 | .B arrayvar | |
5677 | Array variable names. | |
5678 | .TP 8 | |
5679 | .B binding | |
5680 | \fBReadline\fP key binding names. | |
5681 | .TP 8 | |
5682 | .B builtin | |
5683 | Names of shell builtin commands. May also be specified as \fB\-b\fP. | |
5684 | .TP 8 | |
5685 | .B command | |
5686 | Command names. May also be specified as \fB\-c\fP. | |
5687 | .TP 8 | |
5688 | .B directory | |
5689 | Directory names. May also be specified as \fB\-d\fP. | |
5690 | .TP 8 | |
5691 | .B disabled | |
5692 | Names of disabled shell builtins. | |
5693 | .TP 8 | |
5694 | .B enabled | |
5695 | Names of enabled shell builtins. | |
5696 | .TP 8 | |
5697 | .B export | |
5698 | Names of exported shell variables. May also be specified as \fB\-e\fP. | |
5699 | .TP 8 | |
5700 | .B file | |
5701 | File names. May also be specified as \fB\-f\fP. | |
5702 | .TP 8 | |
5703 | .B function | |
5704 | Names of shell functions. | |
5705 | .TP 8 | |
5706 | .B helptopic | |
5707 | Help topics as accepted by the \fBhelp\fP builtin. | |
5708 | .TP 8 | |
5709 | .B hostname | |
5710 | Hostnames, as taken from the file specified by the | |
5711 | .SM | |
5712 | .B HOSTFILE | |
5713 | shell variable. | |
5714 | .TP 8 | |
5715 | .B job | |
5716 | Job names, if job control is active. May also be specified as \fB\-j\fP. | |
5717 | .TP 8 | |
5718 | .B keyword | |
5719 | Shell reserved words. May also be specified as \fB\-k\fP. | |
5720 | .TP 8 | |
5721 | .B running | |
5722 | Names of running jobs, if job control is active. | |
5723 | .TP 8 | |
5724 | .B setopt | |
5725 | Valid arguments for the \fB\-o\fP option to the \fBset\fP builtin. | |
5726 | .TP 8 | |
5727 | .B shopt | |
5728 | Shell option names as accepted by the \fBshopt\fP builtin. | |
5729 | .TP 8 | |
5730 | .B signal | |
5731 | Signal names. | |
5732 | .TP 8 | |
5733 | .B stopped | |
5734 | Names of stopped jobs, if job control is active. | |
5735 | .TP 8 | |
5736 | .B user | |
5737 | User names. May also be specified as \fB\-u\fP. | |
5738 | .TP 8 | |
5739 | .B variable | |
5740 | Names of all shell variables. May also be specified as \fB\-v\fP. | |
5741 | .RE | |
5742 | .TP 8 | |
5743 | \fB\-G\fP \fIglobpat\fP | |
5744 | The filename expansion pattern \fIglobpat\fP is expanded to generate | |
5745 | the possible completions. | |
5746 | .TP 8 | |
5747 | \fB\-W\fP \fIwordlist\fP | |
5748 | The \fIwordlist\fP is split using the characters in the | |
5749 | .SM | |
5750 | .B IFS | |
5751 | special variable as delimiters, and each resultant word is expanded. | |
5752 | The possible completions are the members of the resultant list which | |
5753 | match the word being completed. | |
5754 | .TP 8 | |
5755 | \fB\-C\fP \fIcommand\fP | |
5756 | \fIcommand\fP is executed in a subshell environment, and its output is | |
5757 | used as the possible completions. | |
5758 | .TP 8 | |
5759 | \fB\-F\fP \fIfunction\fP | |
5760 | The shell function \fIfunction\fP is executed in the current shell | |
5761 | environment. | |
5762 | When it finishes, the possible completions are retrieved from the value | |
5763 | of the | |
5764 | .SM | |
5765 | .B COMPREPLY | |
5766 | array variable. | |
5767 | .TP 8 | |
5768 | \fB\-X\fP \fIfilterpat\fP | |
5769 | \fIfilterpat\fP is a pattern as used for filename expansion. | |
5770 | It is applied to the list of possible completions generated by the | |
5771 | preceding options and arguments, and each completion matching | |
5772 | \fIfilterpat\fP is removed from the list. | |
5773 | A leading \fB!\fP in \fIfilterpat\fP negates the pattern; in this | |
5774 | case, any completion not matching \fIfilterpat\fP is removed. | |
5775 | .TP 8 | |
5776 | \fB\-P\fP \fIprefix\fP | |
5777 | \fIprefix\fP is added at the beginning of each possible completion | |
5778 | after all other options have been applied. | |
5779 | .TP 8 | |
5780 | \fB\-S\fP \fIsuffix\fP | |
5781 | \fIsuffix\fP is appended to each possible completion | |
5782 | after all other options have been applied. | |
5783 | .PD | |
5784 | .PP | |
5785 | The return value is true unless an invalid option is supplied, an option | |
5786 | other than \fB\-p\fP or \fB\-r\fP is supplied without a \fIname\fP | |
5787 | argument, an attempt is made to remove a completion specification for | |
5788 | a \fIname\fP for which no specification exists, or | |
5789 | an error occurs adding a completion specification. | |
5790 | .RE | |
5791 | .TP | |
726f6388 JA |
5792 | \fBcontinue\fP [\fIn\fP] |
5793 | Resume the next iteration of the enclosing | |
5794 | .BR for , | |
5795 | .BR while , | |
ccc6cda3 | 5796 | .BR until , |
726f6388 | 5797 | or |
ccc6cda3 | 5798 | .B select |
726f6388 JA |
5799 | loop. |
5800 | If | |
5801 | .I n | |
5802 | is specified, resume at the \fIn\fPth enclosing loop. | |
5803 | .I n | |
5804 | must be \(>= 1. If | |
5805 | .I n | |
5806 | is greater than the number of enclosing loops, the last enclosing loop | |
ccc6cda3 | 5807 | (the ``top-level'' loop) is resumed. The return value is 0 unless the |
726f6388 JA |
5808 | shell is not executing a loop when |
5809 | .B continue | |
5810 | is executed. | |
5811 | .TP | |
5812 | .PD 0 | |
ccc6cda3 | 5813 | \fBdeclare\fP [\fB\-afFirx\fP] [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP]] |
726f6388 | 5814 | .TP |
ccc6cda3 | 5815 | \fBtypeset\fP [\fB\-afFirx\fP] [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP]] |
726f6388 | 5816 | .PD |
ccc6cda3 JA |
5817 | Declare variables and/or give them attributes. |
5818 | If no \fIname\fPs are given then display the values of variables. | |
5819 | The | |
5820 | .B \-p | |
5821 | option will display the attributes and values of each | |
5822 | .IR name . | |
5823 | When | |
5824 | .B \-p | |
5825 | is used, additional options are ignored. | |
5826 | The | |
5827 | .B \-F | |
5828 | option inhibits the display of function definitions; only the | |
5829 | function name and attributes are printed. | |
5830 | The | |
5831 | .B \-F | |
5832 | option implies | |
5833 | .BR \-f . | |
5834 | The following options can | |
5835 | be used to restrict output to variables with the specified attribute or | |
5836 | to give variables attributes: | |
726f6388 JA |
5837 | .RS |
5838 | .PD 0 | |
5839 | .TP | |
ccc6cda3 JA |
5840 | .B \-a |
5841 | Each \fIname\fP is an array variable (see | |
5842 | .B Arrays | |
5843 | above). | |
5844 | .TP | |
726f6388 | 5845 | .B \-f |
ccc6cda3 JA |
5846 | Use function names only. |
5847 | .TP | |
5848 | .B \-i | |
5849 | The variable is treated as an integer; arithmetic evaluation (see | |
5850 | .SM | |
5851 | .B "ARITHMETIC EVALUATION" ") " | |
5852 | is performed when the variable is assigned a value. | |
726f6388 JA |
5853 | .TP |
5854 | .B \-r | |
5855 | Make \fIname\fPs readonly. These names cannot then be assigned values | |
cce855bc | 5856 | by subsequent assignment statements or unset. |
726f6388 JA |
5857 | .TP |
5858 | .B \-x | |
5859 | Mark \fIname\fPs for export to subsequent commands via the environment. | |
726f6388 JA |
5860 | .PD |
5861 | .PP | |
5862 | Using `+' instead of `\-' | |
ccc6cda3 JA |
5863 | turns off the attribute instead, with the exception that \fB+a\fP |
5864 | may not be used to destroy an array variable. When used in a function, | |
5865 | makes each | |
5866 | \fIname\fP local, as with the | |
726f6388 | 5867 | .B local |
cce855bc | 5868 | command. The return value is 0 unless an invalid option is encountered, |
bb70624e JA |
5869 | an attempt is made to define a function using |
5870 | .if n ``\-f foo=bar'', | |
5871 | .if t \f(CW\-f foo=bar\fP, | |
ccc6cda3 JA |
5872 | an attempt is made to assign a value to a readonly variable, |
5873 | an attempt is made to assign a value to an array variable without | |
5874 | using the compound assignment syntax (see | |
5875 | .B Arrays | |
cce855bc | 5876 | above), one of the \fInames\fP is not a valid shell variable name, |
726f6388 | 5877 | an attempt is made to turn off readonly status for a readonly variable, |
ccc6cda3 | 5878 | an attempt is made to turn off array status for an array variable, |
bb70624e | 5879 | or an attempt is made to display a non-existent function with \fB\-f\fP. |
726f6388 JA |
5880 | .RE |
5881 | .TP | |
ccc6cda3 JA |
5882 | .B dirs [\fB\-clpv\fP] [+\fIn\fP] [\-\fIn\fP] |
5883 | Without options, displays the list of currently remembered directories. | |
5884 | The default display is on a single line with directory names separated | |
5885 | by spaces. | |
5886 | Directories are added to the list with the | |
726f6388 JA |
5887 | .B pushd |
5888 | command; the | |
5889 | .B popd | |
ccc6cda3 | 5890 | command removes entries from the list. |
726f6388 JA |
5891 | .RS |
5892 | .PD 0 | |
5893 | .TP | |
ccc6cda3 JA |
5894 | \fB+\fP\fIn\fP |
5895 | Displays the \fIn\fPth entry counting from the left of the list | |
726f6388 JA |
5896 | shown by |
5897 | .B dirs | |
5898 | when invoked without options, starting with zero. | |
5899 | .TP | |
ccc6cda3 JA |
5900 | \fB\-\fP\fIn\fP |
5901 | Displays the \fIn\fPth entry counting from the right of the list | |
726f6388 JA |
5902 | shown by |
5903 | .B dirs | |
5904 | when invoked without options, starting with zero. | |
5905 | .TP | |
ccc6cda3 JA |
5906 | .B \-c |
5907 | Clears the directory stack by deleting all of the entries. | |
5908 | .TP | |
726f6388 | 5909 | .B \-l |
ccc6cda3 | 5910 | Produces a longer listing; the default listing format uses a |
726f6388 | 5911 | tilde to denote the home directory. |
ccc6cda3 JA |
5912 | .TP |
5913 | .B \-p | |
5914 | Print the directory stack with one entry per line. | |
5915 | .TP | |
5916 | .B \-v | |
5917 | Print the directory stack with one entry per line, | |
5918 | prefixing each entry with its index in the stack. | |
726f6388 JA |
5919 | .PD |
5920 | .PP | |
5921 | The return value is 0 unless an | |
cce855bc | 5922 | invalid option is supplied or \fIn\fP indexes beyond the end |
726f6388 JA |
5923 | of the directory stack. |
5924 | .RE | |
5925 | .TP | |
cce855bc | 5926 | \fBdisown\fP [\fB\-ar\fP] [\fB\-h\fP] [\fIjobspec\fP ...] |
ccc6cda3 JA |
5927 | Without options, each |
5928 | .I jobspec | |
5929 | is removed from the table of active jobs. | |
cce855bc JA |
5930 | If the \fB\-h\fP option is given, each |
5931 | .I jobspec | |
5932 | is not removed from the table, but is marked so that | |
ccc6cda3 JA |
5933 | .SM |
5934 | .B SIGHUP | |
5935 | is not sent to the job if the shell receives a | |
5936 | .SM | |
5937 | .BR SIGHUP . | |
5938 | If no | |
5939 | .I jobspec | |
cce855bc JA |
5940 | is present, and neither the |
5941 | .B \-a | |
5942 | nor the | |
5943 | .B \-r | |
5944 | option is supplied, the \fIcurrent job\fP is used. | |
5945 | If no | |
5946 | .I jobspec | |
5947 | is supplied, the | |
5948 | .B \-a | |
5949 | option means to remove or mark all jobs; the | |
5950 | .B \-r | |
5951 | option without a | |
5952 | .I jobspec | |
5953 | argument restricts operation to running jobs. | |
5954 | The return value is 0 unless a | |
ccc6cda3 JA |
5955 | .I jobspec |
5956 | does not specify a valid job. | |
5957 | .TP | |
726f6388 | 5958 | \fBecho\fP [\fB\-neE\fP] [\fIarg\fP ...] |
ccc6cda3 JA |
5959 | Output the \fIarg\fPs, separated by spaces, followed by a newline. |
5960 | The return status is always 0. | |
5961 | If \fB\-n\fP is specified, the trailing newline is | |
726f6388 JA |
5962 | suppressed. If the \fB\-e\fP option is given, interpretation of |
5963 | the following backslash-escaped characters is enabled. The | |
5964 | .B \-E | |
5965 | option disables the interpretation of these escape characters, | |
5966 | even on systems where they are interpreted by default. | |
bb70624e JA |
5967 | The \fBxpg_echo\fP shell option to the may be used to |
5968 | dynamically determine whether or not \fBecho\fP expands these | |
5969 | escape characters by default. | |
ccc6cda3 JA |
5970 | .B echo |
5971 | does not interpret | |
5972 | .B \-\- | |
5973 | to mean the end of options. | |
5974 | .B echo | |
5975 | interprets the following escape sequences: | |
726f6388 JA |
5976 | .RS |
5977 | .PD 0 | |
5978 | .TP | |
5979 | .B \ea | |
5980 | alert (bell) | |
5981 | .TP | |
5982 | .B \eb | |
5983 | backspace | |
5984 | .TP | |
5985 | .B \ec | |
5986 | suppress trailing newline | |
5987 | .TP | |
ccc6cda3 JA |
5988 | .B \ee |
5989 | an escape character | |
5990 | .TP | |
726f6388 JA |
5991 | .B \ef |
5992 | form feed | |
5993 | .TP | |
5994 | .B \en | |
5995 | new line | |
5996 | .TP | |
5997 | .B \er | |
5998 | carriage return | |
5999 | .TP | |
6000 | .B \et | |
6001 | horizontal tab | |
6002 | .TP | |
6003 | .B \ev | |
6004 | vertical tab | |
6005 | .TP | |
6006 | .B \e\e | |
6007 | backslash | |
6008 | .TP | |
cce855bc JA |
6009 | .B \e\fInnn\fP |
6010 | the character whose ASCII code is the octal value \fInnn\fP | |
6011 | (one to three digits) | |
6012 | .TP | |
6013 | .B \ex\fInnn\fP | |
6014 | the character whose ASCII code is the hexadecimal value \fInnn\fP | |
6015 | (one to three digits) | |
726f6388 JA |
6016 | .PD |
6017 | .RE | |
6018 | .TP | |
ccc6cda3 | 6019 | \fBenable\fP [\fB\-adnps\fP] [\fB\-f\fP \fIfilename\fP] [\fIname\fP ...] |
cce855bc JA |
6020 | Enable and disable builtin shell commands. |
6021 | Disabling a builtin allows a disk command which has the same name | |
bb70624e | 6022 | as a shell builtin to be executed without specifying a full pathname, |
cce855bc | 6023 | even though the shell normally searches for builtins before disk commands. |
726f6388 JA |
6024 | If \fB\-n\fP is used, each \fIname\fP |
6025 | is disabled; otherwise, | |
6026 | \fInames\fP are enabled. For example, to use the | |
6027 | .B test | |
6028 | binary found via the | |
6029 | .SM | |
6030 | .B PATH | |
ccc6cda3 JA |
6031 | instead of the shell builtin version, run |
6032 | \f(CWenable -n test\fP. | |
6033 | The | |
6034 | .B \-f | |
6035 | option means to load the new builtin command | |
6036 | .I name | |
6037 | from shared object | |
6038 | .IR filename , | |
6039 | on systems that support dynamic loading. The | |
6040 | .B \-d | |
6041 | option will delete a builtin previously loaded with | |
6042 | .BR \-f . | |
6043 | If no \fIname\fP arguments are given, or if the | |
6044 | .B \-p | |
6045 | option is supplied, a list of shell builtins is printed. | |
6046 | With no other option arguments, the list consists of all enabled | |
6047 | shell builtins. | |
6048 | If \fB\-n\fP is supplied, only disabled builtins are printed. | |
6049 | If \fB\-a\fP is supplied, the list printed includes all builtins, with an | |
726f6388 | 6050 | indication of whether or not each is enabled. |
ccc6cda3 JA |
6051 | If \fB\-s\fP is supplied, the output is restricted to the POSIX |
6052 | \fIspecial\fP builtins. | |
726f6388 JA |
6053 | The return value is 0 unless a |
6054 | .I name | |
bb70624e | 6055 | is not a shell builtin or there is an error loading a new builtin |
ccc6cda3 | 6056 | from a shared object. |
726f6388 JA |
6057 | .TP |
6058 | \fBeval\fP [\fIarg\fP ...] | |
6059 | The \fIarg\fPs are read and concatenated together into a single | |
6060 | command. This command is then read and executed by the shell, and | |
ccc6cda3 JA |
6061 | its exit status is returned as the value of |
6062 | .BR eval . | |
6063 | If there are no | |
726f6388 JA |
6064 | .IR args , |
6065 | or only null arguments, | |
6066 | .B eval | |
ccc6cda3 | 6067 | returns 0. |
726f6388 | 6068 | .TP |
cce855bc | 6069 | \fBexec\fP [\fB\-cl\fP] [\fB\-a\fP \fIname\fP] [\fIcommand\fP [\fIarguments\fP]] |
726f6388 JA |
6070 | If |
6071 | .I command | |
6072 | is specified, it replaces the shell. | |
6073 | No new process is created. The | |
6074 | .I arguments | |
6075 | become the arguments to \fIcommand\fP. | |
ccc6cda3 JA |
6076 | If the |
6077 | .B \-l | |
6078 | option is supplied, | |
bb70624e | 6079 | the shell places a dash at the beginning of the zeroth arg passed to |
726f6388 | 6080 | .IR command . |
ccc6cda3 JA |
6081 | This is what |
6082 | .IR login (1) | |
6083 | does. The | |
6084 | .B \-c | |
6085 | option causes | |
6086 | .I command | |
6087 | to be executed with an empty environment. If | |
6088 | .B \-a | |
6089 | is supplied, the shell passes | |
6090 | .I name | |
6091 | as the zeroth argument to the executed command. If | |
6092 | .I command | |
726f6388 | 6093 | cannot be executed for some reason, a non-interactive shell exits, |
ccc6cda3 JA |
6094 | unless the shell option |
6095 | .B execfail | |
6096 | is enabled, in which case it returns failure. | |
6097 | An interactive shell returns failure if the file cannot be executed. | |
726f6388 JA |
6098 | If |
6099 | .I command | |
6100 | is not specified, any redirections take effect in the current shell, | |
cce855bc JA |
6101 | and the return status is 0. If there is a redirection error, the |
6102 | return status is 1. | |
726f6388 JA |
6103 | .TP |
6104 | \fBexit\fP [\fIn\fP] | |
6105 | Cause the shell to exit | |
6106 | with a status of \fIn\fP. If | |
6107 | .I n | |
6108 | is omitted, the exit status | |
6109 | is that of the last command executed. | |
6110 | A trap on | |
6111 | .SM | |
6112 | .B EXIT | |
6113 | is executed before the shell terminates. | |
6114 | .TP | |
6115 | .PD 0 | |
ccc6cda3 | 6116 | \fBexport\fP [\fB\-fn\fP\^] [\fIname\fP[=\fIword\fP]] ... |
726f6388 JA |
6117 | .TP |
6118 | .B export \-p | |
6119 | .PD | |
6120 | The supplied | |
6121 | .I names | |
6122 | are marked for automatic export to the environment of | |
6123 | subsequently executed commands. If the | |
6124 | .B \-f | |
6125 | option is given, | |
6126 | the | |
6127 | .I names | |
6128 | refer to functions. | |
6129 | If no | |
6130 | .I names | |
6131 | are given, or if the | |
6132 | .B \-p | |
6133 | option is supplied, a list | |
6134 | of all names that are exported in this shell is printed. | |
6135 | The | |
6136 | .B \-n | |
6137 | option causes the export property to be removed from the | |
ccc6cda3 | 6138 | named variables. |
726f6388 | 6139 | .B export |
cce855bc | 6140 | returns an exit status of 0 unless an invalid option is |
726f6388 | 6141 | encountered, |
cce855bc | 6142 | one of the \fInames\fP is not a valid shell variable name, or |
726f6388 JA |
6143 | .B \-f |
6144 | is supplied with a | |
6145 | .I name | |
6146 | that is not a function. | |
6147 | .TP | |
6148 | .PD 0 | |
6149 | \fBfc\fP [\fB\-e\fP \fIename\fP] [\fB\-nlr\fP] [\fIfirst\fP] [\fIlast\fP] | |
6150 | .TP | |
6151 | \fBfc\fP \fB\-s\fP [\fIpat\fP=\fIrep\fP] [\fIcmd\fP] | |
6152 | .PD | |
6153 | Fix Command. In the first form, a range of commands from | |
6154 | .I first | |
6155 | to | |
6156 | .I last | |
6157 | is selected from the history list. | |
6158 | .I First | |
6159 | and | |
6160 | .I last | |
6161 | may be specified as a string (to locate the last command beginning | |
6162 | with that string) or as a number (an index into the history list, | |
6163 | where a negative number is used as an offset from the current | |
6164 | command number). If | |
6165 | .I last | |
6166 | is not specified it is set to | |
6167 | the current command for listing (so that | |
bb70624e JA |
6168 | .if n ``fc \-l \-10'' |
6169 | .if t \f(CWfc \-l \-10\fP | |
726f6388 JA |
6170 | prints the last 10 commands) and to |
6171 | .I first | |
6172 | otherwise. | |
6173 | If | |
6174 | .I first | |
6175 | is not specified it is set to the previous | |
6176 | command for editing and \-16 for listing. | |
6177 | .sp 1 | |
6178 | The | |
6179 | .B \-n | |
cce855bc | 6180 | option suppresses |
726f6388 JA |
6181 | the command numbers when listing. The |
6182 | .B \-r | |
cce855bc | 6183 | option reverses the order of |
726f6388 JA |
6184 | the commands. If the |
6185 | .B \-l | |
cce855bc | 6186 | option is given, |
726f6388 JA |
6187 | the commands are listed on |
6188 | standard output. Otherwise, the editor given by | |
6189 | .I ename | |
6190 | is invoked | |
6191 | on a file containing those commands. If | |
6192 | .I ename | |
6193 | is not given, the | |
6194 | value of the | |
6195 | .SM | |
6196 | .B FCEDIT | |
6197 | variable is used, and | |
6198 | the value of | |
6199 | .SM | |
6200 | .B EDITOR | |
6201 | if | |
6202 | .SM | |
6203 | .B FCEDIT | |
6204 | is not set. If neither variable is set, | |
6205 | .FN vi | |
6206 | is used. When editing is complete, the edited commands are | |
6207 | echoed and executed. | |
6208 | .sp 1 | |
6209 | In the second form, \fIcommand\fP is re-executed after each instance | |
6210 | of \fIpat\fP is replaced by \fIrep\fP. | |
ccc6cda3 JA |
6211 | A useful alias to use with this is |
6212 | .if n ``r=fc -s'', | |
6213 | .if t \f(CWr='fc \-s'\fP, | |
6214 | so that typing | |
6215 | .if n ``r cc'' | |
6216 | .if t \f(CWr cc\fP | |
6217 | runs the last command beginning with | |
6218 | .if n ``cc'' | |
6219 | .if t \f(CWcc\fP | |
6220 | and typing | |
6221 | .if n ``r'' | |
6222 | .if t \f(CWr\fP | |
726f6388 JA |
6223 | re-executes the last command. |
6224 | .sp 1 | |
cce855bc | 6225 | If the first form is used, the return value is 0 unless an invalid |
726f6388 JA |
6226 | option is encountered or |
6227 | .I first | |
6228 | or | |
6229 | .I last | |
6230 | specify history lines out of range. | |
6231 | If the | |
6232 | .B \-e | |
6233 | option is supplied, the return value is the value of the last | |
6234 | command executed or failure if an error occurs with the temporary | |
6235 | file of commands. If the second form is used, the return status | |
6236 | is that of the command re-executed, unless | |
6237 | .I cmd | |
6238 | does not specify a valid history line, in which case | |
6239 | .B fc | |
6240 | returns failure. | |
6241 | .TP | |
6242 | \fBfg\fP [\fIjobspec\fP] | |
cce855bc | 6243 | Resume |
726f6388 | 6244 | .I jobspec |
cce855bc JA |
6245 | in the foreground, and make it the current job. |
6246 | If | |
726f6388 JA |
6247 | .I jobspec |
6248 | is not present, the shell's notion of the \fIcurrent job\fP is used. | |
6249 | The return value is that of the command placed into the foreground, | |
6250 | or failure if run when job control is disabled or, when run with | |
6251 | job control enabled, if | |
6252 | .I jobspec | |
6253 | does not specify a valid job or | |
6254 | .I jobspec | |
6255 | specifies a job that was started without job control. | |
6256 | .TP | |
6257 | \fBgetopts\fP \fIoptstring\fP \fIname\fP [\fIargs\fP] | |
6258 | .B getopts | |
6259 | is used by shell procedures to parse positional parameters. | |
6260 | .I optstring | |
bb70624e | 6261 | contains the option characters to be recognized; if a character |
726f6388 JA |
6262 | is followed by a colon, the option is expected to have an |
6263 | argument, which should be separated from it by white space. | |
bb70624e JA |
6264 | The colon and question mark characters may not be used as |
6265 | option characters. | |
726f6388 JA |
6266 | Each time it is invoked, |
6267 | .B getopts | |
6268 | places the next option in the shell variable | |
6269 | .IR name , | |
6270 | initializing | |
6271 | .I name | |
6272 | if it does not exist, | |
6273 | and the index of the next argument to be processed into the | |
6274 | variable | |
6275 | .SM | |
6276 | .BR OPTIND . | |
6277 | .SM | |
6278 | .B OPTIND | |
6279 | is initialized to 1 each time the shell or a shell script | |
6280 | is invoked. When an option requires an argument, | |
6281 | .B getopts | |
6282 | places that argument into the variable | |
6283 | .SM | |
6284 | .BR OPTARG . | |
6285 | The shell does not reset | |
6286 | .SM | |
6287 | .B OPTIND | |
6288 | automatically; it must be manually reset between multiple | |
6289 | calls to | |
6290 | .B getopts | |
6291 | within the same shell invocation if a new set of parameters | |
6292 | is to be used. | |
6293 | .sp 1 | |
cce855bc JA |
6294 | When the end of options is encountered, \fBgetopts\fP exits with a |
6295 | return value greater than zero. | |
6296 | \fBOPTIND\fP is set to the index of the first non-option argument, | |
6297 | and \fBname\fP is set to ?. | |
6298 | .sp 1 | |
6299 | .B getopts | |
6300 | normally parses the positional parameters, but if more arguments are | |
6301 | given in | |
6302 | .IR args , | |
6303 | .B getopts | |
6304 | parses those instead. | |
6305 | .sp 1 | |
726f6388 JA |
6306 | .B getopts |
6307 | can report errors in two ways. If the first character of | |
6308 | .I optstring | |
6309 | is a colon, | |
6310 | .I silent | |
6311 | error reporting is used. In normal operation diagnostic messages | |
cce855bc | 6312 | are printed when invalid options or missing option arguments are |
726f6388 JA |
6313 | encountered. |
6314 | If the variable | |
6315 | .SM | |
6316 | .B OPTERR | |
cce855bc | 6317 | is set to 0, no error messages will be displayed, even if the first |
726f6388 JA |
6318 | character of |
6319 | .I optstring | |
6320 | is not a colon. | |
6321 | .sp 1 | |
cce855bc | 6322 | If an invalid option is seen, |
726f6388 JA |
6323 | .B getopts |
6324 | places ? into | |
6325 | .I name | |
6326 | and, if not silent, | |
6327 | prints an error message and unsets | |
6328 | .SM | |
6329 | .BR OPTARG . | |
6330 | If | |
6331 | .B getopts | |
6332 | is silent, | |
6333 | the option character found is placed in | |
6334 | .SM | |
6335 | .B OPTARG | |
6336 | and no diagnostic message is printed. | |
6337 | .sp 1 | |
6338 | If a required argument is not found, and | |
6339 | .B getopts | |
6340 | is not silent, | |
6341 | a question mark (\^\fB?\fP\^) is placed in | |
6342 | .IR name , | |
6343 | .B OPTARG | |
6344 | is unset, and a diagnostic message is printed. | |
6345 | If | |
6346 | .B getopts | |
6347 | is silent, then a colon (\^\fB:\fP\^) is placed in | |
6348 | .I name | |
6349 | and | |
6350 | .SM | |
6351 | .B OPTARG | |
6352 | is set to the option character found. | |
6353 | .sp 1 | |
6354 | .B getopts | |
726f6388 JA |
6355 | returns true if an option, specified or unspecified, is found. |
6356 | It returns false if the end of options is encountered or an | |
6357 | error occurs. | |
6358 | .TP | |
ccc6cda3 | 6359 | \fBhash\fP [\fB\-r\fP] [\fB\-p\fP \fIfilename\fP] [\fIname\fP] |
726f6388 JA |
6360 | For each |
6361 | .IR name , | |
ccc6cda3 JA |
6362 | the full file name of the command is determined by searching |
6363 | the directories in | |
6364 | .B $PATH | |
6365 | and remembered. | |
6366 | If the | |
6367 | .B \-p | |
6368 | option is supplied, no path search is performed, and | |
6369 | .I filename | |
6370 | is used as the full file name of the command. | |
6371 | The | |
726f6388 JA |
6372 | .B \-r |
6373 | option causes the shell to forget all | |
6374 | remembered locations. If no arguments are given, information | |
6375 | about remembered commands is printed. | |
ccc6cda3 | 6376 | The return status is true unless a |
726f6388 | 6377 | .I name |
cce855bc | 6378 | is not found or an invalid option is supplied. |
726f6388 | 6379 | .TP |
bb70624e | 6380 | \fBhelp\fP [\fB\-s\fP] [\fIpattern\fP] |
726f6388 JA |
6381 | Display helpful information about builtin commands. If |
6382 | .I pattern | |
6383 | is specified, | |
6384 | .B help | |
6385 | gives detailed help on all commands matching | |
6386 | .IR pattern ; | |
ccc6cda3 | 6387 | otherwise help for all the builtins and shell control structures |
bb70624e JA |
6388 | is printed. |
6389 | The \fB\-s\fP option restricts the information displayed to a short | |
6390 | usage synopsis. | |
6391 | The return status is 0 unless no command matches | |
726f6388 JA |
6392 | .IR pattern . |
6393 | .TP | |
6394 | .PD 0 | |
bb70624e JA |
6395 | \fBhistory [\fIn\fP] |
6396 | .TP | |
6397 | \fBhistory\fP \fB\-c\fP | |
6398 | .TP | |
6399 | \fBhistory \-d\fP \fIoffset\fP | |
ccc6cda3 JA |
6400 | .TP |
6401 | \fBhistory\fP \fB\-anrw\fP [\fIfilename\fP] | |
726f6388 | 6402 | .TP |
ccc6cda3 JA |
6403 | \fBhistory\fP \fB\-p\fP \fIarg\fP [\fIarg ...\fP] |
6404 | .TP | |
6405 | \fBhistory\fP \fB\-s\fP \fIarg\fP [\fIarg ...\fP] | |
726f6388 JA |
6406 | .PD |
6407 | With no options, display the command | |
6408 | history list with line numbers. Lines listed | |
6409 | with a | |
6410 | .B * | |
6411 | have been modified. An argument of | |
6412 | .I n | |
6413 | lists only the last | |
6414 | .I n | |
ccc6cda3 | 6415 | lines. If \fIfilename\fP is supplied, it is used as the |
726f6388 JA |
6416 | name of the history file; if not, the value of |
6417 | .SM | |
6418 | .B HISTFILE | |
6419 | is used. Options, if supplied, have the following meanings: | |
6420 | .RS | |
6421 | .PD 0 | |
6422 | .TP | |
bb70624e JA |
6423 | .B \-c |
6424 | Clear the history list by deleting all the entries. | |
6425 | .TP | |
6426 | \fB\-d\fP \fIoffset\fP | |
6427 | Delete the history entry at position \fIoffset\fP. | |
6428 | .TP | |
726f6388 JA |
6429 | .B \-a |
6430 | Append the ``new'' history lines (history lines entered since the | |
ccc6cda3 | 6431 | beginning of the current \fBbash\fP session) to the history file. |
726f6388 JA |
6432 | .TP |
6433 | .B \-n | |
6434 | Read the history lines not already read from the history | |
6435 | file into the current history list. These are lines | |
6436 | appended to the history file since the beginning of the | |
6437 | current \fBbash\fP session. | |
6438 | .TP | |
6439 | .B \-r | |
6440 | Read the contents of the history file | |
ccc6cda3 | 6441 | and use them as the current history. |
726f6388 JA |
6442 | .TP |
6443 | .B \-w | |
6444 | Write the current history to the history file, overwriting the | |
6445 | history file's contents. | |
ccc6cda3 | 6446 | .TP |
ccc6cda3 JA |
6447 | .B \-p |
6448 | Perform history substitution on the following \fIargs\fP and display | |
6449 | the result on the standard output. | |
6450 | Does not store the results in the history list. | |
6451 | Each \fIarg\fP must be quoted to disable normal history expansion. | |
6452 | .TP | |
6453 | .B \-s | |
6454 | Store the | |
6455 | .I args | |
6456 | in the history list as a single entry. The last command in the | |
6457 | history list is removed before the | |
6458 | .I args | |
6459 | are added. | |
726f6388 JA |
6460 | .PD |
6461 | .PP | |
bb70624e JA |
6462 | The return value is 0 unless an invalid option is encountered, an |
6463 | error occurs while reading or writing the history file, an invalid | |
6464 | \fIoffset\fP is supplied as an argument to \fB\-d\fP, or the | |
6465 | history expansion supplied as an argument to \fB\-p\fP fails. | |
726f6388 JA |
6466 | .RE |
6467 | .TP | |
6468 | .PD 0 | |
ccc6cda3 | 6469 | \fBjobs\fP [\fB\-lnprs\fP] [ \fIjobspec\fP ... ] |
726f6388 JA |
6470 | .TP |
6471 | \fBjobs\fP \fB\-x\fP \fIcommand\fP [ \fIargs\fP ... ] | |
6472 | .PD | |
ccc6cda3 JA |
6473 | The first form lists the active jobs. The options have the following |
6474 | meanings: | |
6475 | .RS | |
6476 | .PD 0 | |
6477 | .TP | |
726f6388 | 6478 | .B \-l |
ccc6cda3 JA |
6479 | List process IDs |
6480 | in addition to the normal information. | |
6481 | .TP | |
726f6388 | 6482 | .B \-p |
ccc6cda3 JA |
6483 | List only the process ID of the job's process group |
6484 | leader. | |
6485 | .TP | |
726f6388 | 6486 | .B \-n |
ccc6cda3 JA |
6487 | Display information only about jobs that have changed status since |
6488 | the user was last notified of their status. | |
6489 | .TP | |
6490 | .B \-r | |
6491 | Restrict output to running jobs. | |
6492 | .TP | |
6493 | .B \-s | |
6494 | Restrict output to stopped jobs. | |
6495 | .PD | |
6496 | .PP | |
6497 | If | |
726f6388 JA |
6498 | .I jobspec |
6499 | is given, output is restricted to information about that job. | |
cce855bc JA |
6500 | The return status is 0 unless an invalid option is encountered |
6501 | or an invalid | |
726f6388 JA |
6502 | .I jobspec |
6503 | is supplied. | |
ccc6cda3 | 6504 | .PP |
726f6388 JA |
6505 | If the |
6506 | .B \-x | |
6507 | option is supplied, | |
6508 | .B jobs | |
6509 | replaces any | |
6510 | .I jobspec | |
6511 | found in | |
6512 | .I command | |
6513 | or | |
6514 | .I args | |
6515 | with the corresponding process group ID, and executes | |
6516 | .I command | |
6517 | passing it | |
6518 | .IR args , | |
6519 | returning its exit status. | |
ccc6cda3 | 6520 | .RE |
726f6388 JA |
6521 | .TP |
6522 | .PD 0 | |
ccc6cda3 | 6523 | \fBkill\fP [\fB\-s\fP \fIsigspec\fP | \fB\-n\fP \fIsignum\fP | \fB\-\fP\fIsigspec\fP] [\fIpid\fP | \fIjobspec\fP] ... |
726f6388 | 6524 | .TP |
cce855bc | 6525 | \fBkill\fP \fB\-l\fP [\fIsigspec\fP | \fIexit_status\fP] |
726f6388 JA |
6526 | .PD |
6527 | Send the signal named by | |
6528 | .I sigspec | |
ccc6cda3 JA |
6529 | or |
6530 | .I signum | |
726f6388 JA |
6531 | to the processes named by |
6532 | .I pid | |
6533 | or | |
6534 | .IR jobspec . | |
6535 | .I sigspec | |
6536 | is either a signal name such as | |
6537 | .SM | |
6538 | .B SIGKILL | |
ccc6cda3 JA |
6539 | or a signal number; |
6540 | .I signum | |
6541 | is a signal number. If | |
726f6388 | 6542 | .I sigspec |
ccc6cda3 | 6543 | is a signal name, the name may be |
726f6388 JA |
6544 | given with or without the |
6545 | .SM | |
6546 | .B SIG | |
6547 | prefix. | |
6548 | If | |
6549 | .I sigspec | |
6550 | is not present, then | |
6551 | .SM | |
6552 | .B SIGTERM | |
cce855bc JA |
6553 | is assumed. |
6554 | An argument of | |
726f6388 | 6555 | .B \-l |
cce855bc JA |
6556 | lists the signal names. |
6557 | If any arguments are supplied when | |
726f6388 | 6558 | .B \-l |
cce855bc JA |
6559 | is given, the names of the signals corresponding to the arguments are |
6560 | listed, and the return status is 0. | |
6561 | The \fIexit_status\fP argument to | |
ccc6cda3 | 6562 | .B \-l |
cce855bc JA |
6563 | is a number specifying either a signal number or the exit status of |
6564 | a process terminated by a signal. | |
726f6388 JA |
6565 | .B kill |
6566 | returns true if at least one signal was successfully sent, or false | |
cce855bc | 6567 | if an error occurs or an invalid option is encountered. |
726f6388 JA |
6568 | .TP |
6569 | \fBlet\fP \fIarg\fP [\fIarg\fP ...] | |
6570 | Each | |
6571 | .I arg | |
6572 | is an arithmetic expression to be evaluated (see | |
6573 | .SM | |
6574 | .BR "ARITHMETIC EVALUATION" ). | |
6575 | If the last | |
6576 | .I arg | |
6577 | evaluates to 0, | |
6578 | .B let | |
6579 | returns 1; 0 is returned otherwise. | |
6580 | .TP | |
bb70624e | 6581 | \fBlocal\fP [\fIoption\fP] [\fIname\fP[=\fIvalue\fP] ...] |
cce855bc JA |
6582 | For each argument, a local variable named |
6583 | .I name | |
6584 | is created, and assigned | |
726f6388 | 6585 | .IR value . |
bb70624e | 6586 | The \fIoption\fP can be any of the options accepted by \fBdeclare\fP. |
726f6388 JA |
6587 | When |
6588 | .B local | |
6589 | is used within a function, it causes the variable | |
6590 | .I name | |
6591 | to have a visible scope restricted to that function and its children. | |
6592 | With no operands, | |
6593 | .B local | |
6594 | writes a list of local variables to the standard output. It is | |
6595 | an error to use | |
6596 | .B local | |
6597 | when not within a function. The return status is 0 unless | |
6598 | .B local | |
bb70624e | 6599 | is used outside a function, an invalid |
726f6388 | 6600 | .I name |
bb70624e JA |
6601 | is supplied, or |
6602 | \fIname\fP is a readonly variable. | |
726f6388 JA |
6603 | .TP |
6604 | .B logout | |
6605 | Exit a login shell. | |
6606 | .TP | |
ccc6cda3 | 6607 | \fBpopd\fP [\-\fBn\fP] [+\fIn\fP] [\-\fIn\fP] |
726f6388 JA |
6608 | Removes entries from the directory stack. With no arguments, |
6609 | removes the top directory from the stack, and performs a | |
6610 | .B cd | |
6611 | to the new top directory. | |
ccc6cda3 | 6612 | Arguments, if supplied, have the following meanings: |
726f6388 JA |
6613 | .RS |
6614 | .PD 0 | |
6615 | .TP | |
ccc6cda3 JA |
6616 | \fB+\fP\fIn\fP |
6617 | Removes the \fIn\fPth entry counting from the left of the list | |
726f6388 JA |
6618 | shown by |
6619 | .BR dirs , | |
bb70624e JA |
6620 | starting with zero. For example: |
6621 | .if n ``popd +0'' | |
6622 | .if t \f(CWpopd +0\fP | |
6623 | removes the first directory, | |
6624 | .if n ``popd +1'' | |
6625 | .if t \f(CWpopd +1\fP | |
6626 | the second. | |
726f6388 | 6627 | .TP |
ccc6cda3 JA |
6628 | \fB\-\fP\fIn\fP |
6629 | Removes the \fIn\fPth entry counting from the right of the list | |
726f6388 JA |
6630 | shown by |
6631 | .BR dirs , | |
bb70624e JA |
6632 | starting with zero. For example: |
6633 | .if n ``popd -0'' | |
6634 | .if t \f(CWpopd -0\fP | |
6635 | removes the last directory, | |
6636 | .if n ``popd -1'' | |
6637 | .if t \f(CWpopd -1\fP | |
6638 | the next to last. | |
ccc6cda3 JA |
6639 | .TP |
6640 | .B \-n | |
6641 | Suppresses the normal change of directory when removing directories | |
6642 | from the stack, so that only the stack is manipulated. | |
726f6388 JA |
6643 | .PD |
6644 | .PP | |
6645 | If the | |
6646 | .B popd | |
6647 | command is successful, a | |
6648 | .B dirs | |
6649 | is performed as well, and the return status is 0. | |
6650 | .B popd | |
cce855bc | 6651 | returns false if an invalid option is encountered, the directory stack |
726f6388 JA |
6652 | is empty, a non-existent directory stack entry is specified, or the |
6653 | directory change fails. | |
6654 | .RE | |
6655 | .TP | |
cce855bc JA |
6656 | \fBprintf\fP \fIformat\fP [\fIarguments\fP] |
6657 | Write the formatted \fIarguments\fP to the standard output under the | |
6658 | control of the \fIformat\fP. | |
6659 | The \fIformat\fP is a character string which contains three types of objects: | |
6660 | plain characters, which are simply copied to standard output, character | |
6661 | escape sequences, which are converted and copied to the standard output, and | |
6662 | format specifications, each of which causes printing of the next successive | |
6663 | \fIargument\fP. | |
6664 | In addition to the standard \fIprintf\fP(1) formats, %b causes | |
6665 | \fBprintf\fP to expand backslash escape sequences in the corresponding | |
6666 | \fIargument\fP, and %q causes \fBprintf\fP to output the corresponding | |
6667 | \fIargument\fP in a format that can be reused as shell input. | |
6668 | .sp 1 | |
6669 | The \fIformat\fP is reused as necessary to consume all of the \fIarguments\fP. | |
6670 | If the \fIformat\fP requires more \fIarguments\fP than are supplied, the | |
6671 | extra format specifications behave as if a zero value or null string, as | |
bb70624e JA |
6672 | appropriate, had been supplied. The return value is zero on success, |
6673 | non-zero on failure. | |
cce855bc | 6674 | .TP |
726f6388 | 6675 | .PD 0 |
ccc6cda3 | 6676 | \fBpushd\fP [\fB\-n\fP] [\fIdir\fP] |
726f6388 | 6677 | .TP |
ccc6cda3 | 6678 | \fBpushd\fP [\fB\-n\fP] [+\fIn\fP] [\-\fIn\fP] |
726f6388 JA |
6679 | .PD |
6680 | Adds a directory to the top of the directory stack, or rotates | |
6681 | the stack, making the new top of the stack the current working | |
6682 | directory. With no arguments, exchanges the top two directories | |
6683 | and returns 0, unless the directory stack is empty. | |
ccc6cda3 | 6684 | Arguments, if supplied, have the following meanings: |
726f6388 JA |
6685 | .RS |
6686 | .PD 0 | |
6687 | .TP | |
ccc6cda3 | 6688 | \fB+\fP\fIn\fP |
726f6388 JA |
6689 | Rotates the stack so that the \fIn\fPth directory |
6690 | (counting from the left of the list shown by | |
d166f048 JA |
6691 | .BR dirs , |
6692 | starting with zero) | |
726f6388 JA |
6693 | is at the top. |
6694 | .TP | |
ccc6cda3 | 6695 | \fB\-\fP\fIn\fP |
726f6388 | 6696 | Rotates the stack so that the \fIn\fPth directory |
d166f048 JA |
6697 | (counting from the right of the list shown by |
6698 | .BR dirs , | |
6699 | starting with zero) is at the top. | |
726f6388 | 6700 | .TP |
ccc6cda3 JA |
6701 | .B \-n |
6702 | Suppresses the normal change of directory when adding directories | |
6703 | to the stack, so that only the stack is manipulated. | |
6704 | .TP | |
bb70624e | 6705 | .I dir |
ccc6cda3 | 6706 | Adds |
726f6388 JA |
6707 | .I dir |
6708 | to the directory stack at the top, making it the | |
6709 | new current working directory. | |
6710 | .PD | |
6711 | .PP | |
6712 | If the | |
6713 | .B pushd | |
6714 | command is successful, a | |
6715 | .B dirs | |
6716 | is performed as well. | |
6717 | If the first form is used, | |
6718 | .B pushd | |
6719 | returns 0 unless the cd to | |
6720 | .I dir | |
6721 | fails. With the second form, | |
6722 | .B pushd | |
6723 | returns 0 unless the directory stack is empty, | |
ccc6cda3 | 6724 | a non-existent directory stack element is specified, |
726f6388 JA |
6725 | or the directory change to the specified new current directory |
6726 | fails. | |
6727 | .RE | |
6728 | .TP | |
ccc6cda3 | 6729 | \fBpwd\fP [\fB\-LP\fP] |
bb70624e JA |
6730 | Print the absolute pathname of the current working directory. |
6731 | The pathname printed contains no symbolic links if the | |
726f6388 | 6732 | .B \-P |
ccc6cda3 JA |
6733 | option is supplied or the |
6734 | .B \-o physical | |
726f6388 JA |
6735 | option to the |
6736 | .B set | |
ccc6cda3 JA |
6737 | builtin command is enabled. |
6738 | If the | |
6739 | .B \-L | |
bb70624e | 6740 | option is used, the pathname printed may contain symbolic links. |
ccc6cda3 | 6741 | The return status is 0 unless an error occurs while |
cce855bc JA |
6742 | reading the name of the current directory or an |
6743 | invalid option is supplied. | |
726f6388 | 6744 | .TP |
bb70624e | 6745 | \fBread\fP [\fB\-ers\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 ...] |
726f6388 JA |
6746 | One line is read from the standard input, and the first word |
6747 | is assigned to the first | |
6748 | .IR name , | |
6749 | the second word to the second | |
6750 | .IR name , | |
cce855bc JA |
6751 | and so on, with leftover words and their intervening separators assigned |
6752 | to the last | |
726f6388 | 6753 | .IR name . |
cce855bc JA |
6754 | If there are fewer words read from the standard input than names, |
6755 | the remaining names are assigned empty values. | |
6756 | The characters in | |
726f6388 JA |
6757 | .SM |
6758 | .B IFS | |
cce855bc | 6759 | are used to split the line into words. |
b72432fd JA |
6760 | The backslash character (\fB\e\fP) may be used to remove any special |
6761 | meaning for the next character read and for line continuation. | |
cce855bc | 6762 | Options, if supplied, have the following meanings: |
ccc6cda3 JA |
6763 | .RS |
6764 | .PD 0 | |
6765 | .TP | |
bb70624e | 6766 | .B \-a \fIaname\fP |
ccc6cda3 JA |
6767 | The words are assigned to sequential indices |
6768 | of the array variable | |
6769 | .IR aname , | |
6770 | starting at 0. | |
6771 | .I aname | |
6772 | is unset before any new values are assigned. | |
cce855bc | 6773 | Other \fIname\fP arguments are ignored. |
ccc6cda3 | 6774 | .TP |
bb70624e JA |
6775 | .B \-d \fIdelim\fP |
6776 | The first character of \fIdelim\fP is used to terminate the input line, | |
6777 | rather than newline. | |
6778 | .TP | |
ccc6cda3 JA |
6779 | .B \-e |
6780 | If the standard input | |
6781 | is coming from a terminal, | |
6782 | .B readline | |
6783 | (see | |
6784 | .SM | |
6785 | .B READLINE | |
6786 | above) is used to obtain the line. | |
bb70624e JA |
6787 | .TP |
6788 | .B \-n \fInchars\fP | |
6789 | \fBread\fP returns after reading \fInchars\fP characters rather than | |
6790 | waiting for a complete line of input. | |
6791 | .TP | |
6792 | .B \-p \fIprompt\fP | |
6793 | Display \fIprompt\fP, without a | |
6794 | trailing newline, before attempting to read any input. The prompt | |
6795 | is displayed only if input is coming from a terminal. | |
6796 | .TP | |
6797 | .B \-r | |
6798 | Backslash does not act as an escape character. | |
6799 | The backslash is considered to be part of the line. | |
6800 | In particular, a backslash-newline pair may not be used as a line | |
6801 | continuation. | |
6802 | .TP | |
6803 | .B \-s | |
6804 | Silent mode. If input is coming from a terminal, characters are | |
6805 | not echoed. | |
6806 | .TP | |
6807 | .B \-t \fItimeout\fP | |
6808 | Cause \fBread\fP to time out and return failure if a complete line of | |
6809 | input is not read within \fItimeout\fP seconds. | |
6810 | This option has no effect if \fBread\fP is not reading input from the | |
6811 | terminal or a pipe. | |
ccc6cda3 JA |
6812 | .PD |
6813 | .PP | |
6814 | If no | |
726f6388 JA |
6815 | .I names |
6816 | are supplied, the line read is assigned to the variable | |
6817 | .SM | |
6818 | .BR REPLY . | |
bb70624e JA |
6819 | The return code is zero, unless end-of-file is encountered or \fBread\fP |
6820 | times out. | |
ccc6cda3 | 6821 | .RE |
726f6388 | 6822 | .TP |
ccc6cda3 | 6823 | \fBreadonly\fP [\fB\-apf\fP] [\fIname\fP ...] |
726f6388 JA |
6824 | .PD |
6825 | The given | |
ccc6cda3 JA |
6826 | \fInames\fP are marked readonly; the values of these |
6827 | .I names | |
726f6388 JA |
6828 | may not be changed by subsequent assignment. |
6829 | If the | |
6830 | .B \-f | |
6831 | option is supplied, the functions corresponding to the | |
6832 | \fInames\fP are so | |
ccc6cda3 JA |
6833 | marked. |
6834 | The | |
6835 | .B \-a | |
6836 | option restricts the variables to arrays. | |
6837 | If no | |
6838 | .I name | |
6839 | arguments are given, or if the | |
726f6388 | 6840 | .B \-p |
ccc6cda3 | 6841 | option is supplied, a list of all readonly names is printed. |
cce855bc JA |
6842 | The |
6843 | .B \-p | |
bb70624e JA |
6844 | option causes output to be displayed in a format that |
6845 | may be reused as input. | |
cce855bc | 6846 | The return status is 0 unless an invalid option is encountered, |
ccc6cda3 JA |
6847 | one of the |
6848 | .I names | |
cce855bc | 6849 | is not a valid shell variable name, or |
726f6388 JA |
6850 | .B \-f |
6851 | is supplied with a | |
6852 | .I name | |
6853 | that is not a function. | |
6854 | .TP | |
6855 | \fBreturn\fP [\fIn\fP] | |
6856 | Causes a function to exit with the return value specified by | |
6857 | .IR n . | |
6858 | If | |
6859 | .I n | |
6860 | is omitted, the return status is that of the last command | |
6861 | executed in the function body. If used outside a function, | |
6862 | but during execution of a script by the | |
6863 | .B . | |
6864 | (\fBsource\fP) command, it causes the shell to stop executing | |
6865 | that script and return either | |
6866 | .I n | |
6867 | or the exit status of the last command executed within the | |
6868 | script as the exit status of the script. If used outside a | |
6869 | function and not during execution of a script by \fB.\fP\^, | |
6870 | the return status is false. | |
6871 | .TP | |
ccc6cda3 JA |
6872 | \fBset\fP [\fB\-\-abefhkmnptuvxBCHP\fP] [\fB\-o\fP \fIoption\fP] [\fIarg\fP ...] |
6873 | Without options, the name and value of each shell variable are displayed | |
cce855bc JA |
6874 | in a format that can be reused as input. |
6875 | The output is sorted according to the current locale. | |
ccc6cda3 JA |
6876 | When options are specified, they set or unset shell attributes. |
6877 | Any arguments remaining after the options are processed are treated | |
6878 | as values for the positional parameters and are assigned, in order, to | |
6879 | .BR $1 , | |
6880 | .BR $2 , | |
6881 | .B ... | |
6882 | .BR $\fIn\fP . | |
6883 | Options, if specified, have the following meanings: | |
726f6388 JA |
6884 | .RS |
6885 | .PD 0 | |
6886 | .TP 8 | |
6887 | .B \-a | |
6888 | Automatically mark variables which are modified or created for export | |
6889 | to the environment of subsequent commands. | |
6890 | .TP 8 | |
6891 | .B \-b | |
ccc6cda3 JA |
6892 | Report the status of terminated background jobs |
6893 | immediately, rather than before the next primary prompt. This is | |
6894 | effective only when job control is enabled. | |
726f6388 JA |
6895 | .TP 8 |
6896 | .B \-e | |
ccc6cda3 | 6897 | Exit immediately if a \fIsimple command\fP (see |
726f6388 JA |
6898 | .SM |
6899 | .B SHELL GRAMMAR | |
ccc6cda3 | 6900 | above) exits with a non-zero status. The shell does not exit if the |
726f6388 JA |
6901 | command that fails is part of an |
6902 | .I until | |
6903 | or | |
6904 | .I while | |
6905 | loop, | |
6906 | part of an | |
6907 | .I if | |
6908 | statement, part of a | |
6909 | .B && | |
6910 | or | |
ccc6cda3 | 6911 | .B \(bv\(bv |
726f6388 JA |
6912 | list, or if the command's return value is |
6913 | being inverted via | |
6914 | .BR ! . | |
6915 | .TP 8 | |
6916 | .B \-f | |
6917 | Disable pathname expansion. | |
6918 | .TP 8 | |
6919 | .B \-h | |
ccc6cda3 | 6920 | Remember the location of commands as they are looked up for execution. |
cce855bc | 6921 | This is enabled by default. |
726f6388 JA |
6922 | .TP 8 |
6923 | .B \-k | |
ccc6cda3 JA |
6924 | All arguments in the form of assignment statements |
6925 | are placed in the environment for a command, not just | |
6926 | those that precede the command name. | |
726f6388 JA |
6927 | .TP 8 |
6928 | .B \-m | |
cce855bc | 6929 | Monitor mode. Job control is enabled. This option is on |
726f6388 JA |
6930 | by default for interactive shells on systems that support |
6931 | it (see | |
6932 | .SM | |
6933 | .B JOB CONTROL | |
6934 | above). Background processes run in a separate process | |
6935 | group and a line containing their exit status is printed | |
6936 | upon their completion. | |
6937 | .TP 8 | |
6938 | .B \-n | |
6939 | Read commands but do not execute them. This may be used to | |
ccc6cda3 | 6940 | check a shell script for syntax errors. This is ignored by |
726f6388 JA |
6941 | interactive shells. |
6942 | .TP 8 | |
ccc6cda3 JA |
6943 | .B \-o \fIoption\-name\fP |
6944 | The \fIoption\-name\fP can be one of the following: | |
726f6388 JA |
6945 | .RS |
6946 | .TP 8 | |
6947 | .B allexport | |
6948 | Same as | |
6949 | .BR \-a . | |
6950 | .TP 8 | |
6951 | .B braceexpand | |
ccc6cda3 JA |
6952 | Same as |
6953 | .BR \-B . | |
726f6388 JA |
6954 | .TP 8 |
6955 | .B emacs | |
6956 | Use an emacs-style command line editing interface. This is enabled | |
6957 | by default when the shell is interactive, unless the shell is started | |
6958 | with the | |
ccc6cda3 | 6959 | .B \-\-noediting |
726f6388 JA |
6960 | option. |
6961 | .TP 8 | |
6962 | .B errexit | |
6963 | Same as | |
6964 | .BR \-e . | |
6965 | .TP 8 | |
ccc6cda3 JA |
6966 | .B hashall |
6967 | Same as | |
6968 | .BR \-h . | |
6969 | .TP 8 | |
726f6388 JA |
6970 | .B histexpand |
6971 | Same as | |
6972 | .BR \-H . | |
6973 | .TP 8 | |
ccc6cda3 JA |
6974 | .B history |
6975 | Enable command history, as described above under | |
6976 | .SM | |
6977 | .BR HISTORY . | |
6978 | This option is on by default in interactive shells. | |
6979 | .TP 8 | |
726f6388 | 6980 | .B ignoreeof |
ccc6cda3 | 6981 | The effect is as if the shell command \f(CWIGNOREEOF=10\fP had been executed |
726f6388 JA |
6982 | (see |
6983 | .B Shell Variables | |
6984 | above). | |
6985 | .TP 8 | |
ccc6cda3 JA |
6986 | .B keyword |
6987 | Same as | |
6988 | .BR \-k . | |
726f6388 JA |
6989 | .TP 8 |
6990 | .B monitor | |
6991 | Same as | |
6992 | .BR \-m . | |
6993 | .TP 8 | |
6994 | .B noclobber | |
6995 | Same as | |
6996 | .BR \-C . | |
6997 | .TP 8 | |
6998 | .B noexec | |
6999 | Same as | |
7000 | .BR \-n . | |
7001 | .TP 8 | |
7002 | .B noglob | |
7003 | Same as | |
7004 | .BR \-f . | |
7005 | .TP 8 | |
726f6388 JA |
7006 | .B notify |
7007 | Same as | |
7008 | .BR \-b . | |
7009 | .TP 8 | |
7010 | .B nounset | |
7011 | Same as | |
7012 | .BR \-u . | |
7013 | .TP 8 | |
ccc6cda3 JA |
7014 | .B onecmd |
7015 | Same as | |
7016 | .BR \-t . | |
7017 | .TP 8 | |
726f6388 JA |
7018 | .B physical |
7019 | Same as | |
7020 | .BR \-P . | |
7021 | .TP 8 | |
7022 | .B posix | |
ccc6cda3 JA |
7023 | Change the behavior of |
7024 | .B bash | |
7025 | where the default operation differs | |
7026 | from the POSIX 1003.2 standard to match the standard. | |
726f6388 JA |
7027 | .TP 8 |
7028 | .B privileged | |
7029 | Same as | |
7030 | .BR \-p . | |
7031 | .TP 8 | |
7032 | .B verbose | |
7033 | Same as | |
7034 | .BR \-v . | |
7035 | .TP 8 | |
7036 | .B vi | |
7037 | Use a vi-style command line editing interface. | |
7038 | .TP 8 | |
7039 | .B xtrace | |
7040 | Same as | |
7041 | .BR \-x . | |
ccc6cda3 | 7042 | .sp .5 |
726f6388 | 7043 | .PP |
ccc6cda3 JA |
7044 | If |
7045 | .B \-o | |
7046 | is supplied with no \fIoption\-name\fP, the values of the current options are | |
726f6388 | 7047 | printed. |
ccc6cda3 JA |
7048 | If |
7049 | .B +o | |
7050 | is supplied with no \fIoption\-name\fP, a series of | |
7051 | .B set | |
7052 | commands to recreate the current option settings is displayed on | |
7053 | the standard output. | |
726f6388 JA |
7054 | .RE |
7055 | .TP 8 | |
7056 | .B \-p | |
7057 | Turn on | |
7058 | .I privileged | |
7059 | mode. In this mode, the | |
bb70624e | 7060 | .SM |
726f6388 | 7061 | .B $ENV |
b72432fd | 7062 | and |
bb70624e | 7063 | .SM |
b72432fd JA |
7064 | .B $BASH_ENV |
7065 | files are not processed, shell functions are not inherited from the | |
bb70624e JA |
7066 | environment, and the |
7067 | .SM | |
7068 | .B SHELLOPTS | |
7069 | variable, if it appears in the environment, is ignored. | |
b72432fd JA |
7070 | If the shell is started with the effective user (group) id not equal to the |
7071 | real user (group) id, and the \fB\-p\fP option is not supplied, these actions | |
7072 | are taken and the effective user id is set to the real user id. | |
7073 | If the \fB\-p\fP option is supplied at startup, the effective user id is | |
7074 | not reset. | |
cce855bc | 7075 | Turning this option off causes the effective user |
726f6388 JA |
7076 | and group ids to be set to the real user and group ids. |
7077 | .TP 8 | |
7078 | .B \-t | |
7079 | Exit after reading and executing one command. | |
7080 | .TP 8 | |
7081 | .B \-u | |
7082 | Treat unset variables as an error when performing | |
7083 | parameter expansion. If expansion is attempted on an | |
7084 | unset variable, the shell prints an error message, and, | |
ccc6cda3 | 7085 | if not interactive, exits with a non-zero status. |
726f6388 JA |
7086 | .TP 8 |
7087 | .B \-v | |
7088 | Print shell input lines as they are read. | |
7089 | .TP 8 | |
7090 | .B \-x | |
ccc6cda3 JA |
7091 | After expanding each \fIsimple command\fP, |
7092 | display the expanded value of | |
726f6388 JA |
7093 | .SM |
7094 | .BR PS4 , | |
7095 | followed by the command and its expanded arguments. | |
7096 | .TP 8 | |
ccc6cda3 JA |
7097 | .B \-B |
7098 | The shell performs brace expansion (see | |
7099 | .B Brace Expansion | |
7100 | above). This is on by default. | |
726f6388 JA |
7101 | .TP 8 |
7102 | .B \-C | |
ccc6cda3 JA |
7103 | If set, |
7104 | .B bash | |
7105 | does not overwrite an existing file with the | |
7106 | .BR > , | |
7107 | .BR >& , | |
7108 | and | |
7109 | .B <> | |
7110 | redirection operators. This may be overridden when | |
7111 | creating output files by using the redirection operator | |
7112 | .B >| | |
7113 | instead of | |
7114 | .BR > . | |
726f6388 JA |
7115 | .TP 8 |
7116 | .B \-H | |
7117 | Enable | |
7118 | .B ! | |
cce855bc | 7119 | style history substitution. This option is on by |
726f6388 JA |
7120 | default when the shell is interactive. |
7121 | .TP 8 | |
7122 | .B \-P | |
ccc6cda3 JA |
7123 | If set, the shell does not follow symbolic links when executing |
7124 | commands such as | |
726f6388 | 7125 | .B cd |
ccc6cda3 JA |
7126 | that change the current working directory. It uses the |
7127 | physical directory structure instead. By default, | |
7128 | .B bash | |
7129 | follows the logical chain of directories when performing commands | |
7130 | which change the current directory. | |
726f6388 JA |
7131 | .TP 8 |
7132 | .B \-\- | |
cce855bc | 7133 | If no arguments follow this option, then the positional parameters are |
726f6388 JA |
7134 | unset. Otherwise, the positional parameters are set to the |
7135 | \fIarg\fPs, even if some of them begin with a | |
7136 | .BR \- . | |
7137 | .TP 8 | |
7138 | .B \- | |
7139 | Signal the end of options, cause all remaining \fIarg\fPs to be | |
7140 | assigned to the positional parameters. The | |
7141 | .B \-x | |
7142 | and | |
7143 | .B \-v | |
7144 | options are turned off. | |
7145 | If there are no \fIarg\fPs, | |
7146 | the positional parameters remain unchanged. | |
7147 | .PD | |
7148 | .PP | |
cce855bc JA |
7149 | The options are off by default unless otherwise noted. |
7150 | Using + rather than \- causes these options to be turned off. | |
7151 | The options can also be specified as arguments to an invocation of | |
7152 | the shell. | |
7153 | The current set of options may be found in | |
726f6388 | 7154 | .BR $\- . |
cce855bc | 7155 | The return status is always true unless an invalid option is encountered. |
726f6388 JA |
7156 | .RE |
7157 | .TP | |
7158 | \fBshift\fP [\fIn\fP] | |
7159 | The positional parameters from \fIn\fP+1 ... are renamed to | |
7160 | .B $1 | |
7161 | .B .... | |
7162 | Parameters represented by the numbers \fB$#\fP | |
7163 | down to \fB$#\fP\-\fIn\fP+1 are unset. | |
ccc6cda3 JA |
7164 | .I n |
7165 | must be a non-negative number less than or equal to \fB$#\fP. | |
726f6388 JA |
7166 | If |
7167 | .I n | |
7168 | is 0, no parameters are changed. | |
7169 | If | |
7170 | .I n | |
7171 | is not given, it is assumed to be 1. | |
726f6388 JA |
7172 | If |
7173 | .I n | |
7174 | is greater than \fB$#\fP, the positional parameters are not changed. | |
ccc6cda3 | 7175 | The return status is greater than zero if |
726f6388 JA |
7176 | .I n |
7177 | is greater than | |
7178 | .B $# | |
ccc6cda3 JA |
7179 | or less than zero; otherwise 0. |
7180 | .TP | |
7181 | \fBshopt\fP [\fB\-pqsu\fP] [\fB\-o\fP] [\fIoptname\fP ...] | |
7182 | Toggle the values of variables controlling optional shell behavior. | |
7183 | With no options, or with the | |
7184 | .B \-p | |
7185 | option, a list of all settable options is displayed, with | |
cce855bc JA |
7186 | an indication of whether or not each is set. |
7187 | The \fB\-p\fP option causes output to be displayed in a form that | |
7188 | may be reused as input. | |
7189 | Other options have the following meanings: | |
ccc6cda3 JA |
7190 | .RS |
7191 | .PD 0 | |
7192 | .TP | |
7193 | .B \-s | |
7194 | Enable (set) each \fIoptname\fP. | |
7195 | .TP | |
7196 | .B \-u | |
7197 | Disable (unset) each \fIoptname\fP. | |
7198 | .TP | |
7199 | .B \-q | |
7200 | Suppresses normal output (quiet mode); the return status indicates | |
7201 | whether the \fIoptname\fP is set or unset. | |
7202 | If multiple \fIoptname\fP arguments are given with | |
7203 | .BR \-q , | |
7204 | the return status is zero if all \fIoptnames\fP are enabled; non-zero | |
7205 | otherwise. | |
7206 | .TP | |
7207 | .B \-o | |
7208 | Restricts the values of \fIoptname\fP to be those defined for the | |
7209 | .B \-o | |
7210 | option to the | |
7211 | .B set | |
7212 | builtin. | |
7213 | .PD | |
7214 | .PP | |
7215 | If either | |
7216 | .B \-s | |
7217 | or | |
7218 | .B \-u | |
7219 | is used with no \fIoptname\fP arguments, the display is limited to | |
7220 | those options which are set or unset, respectively. | |
7221 | Unless otherwise noted, the \fBshopt\fP options are disabled (unset) | |
7222 | by default. | |
7223 | .PP | |
7224 | The return status when listing options is zero if all \fIoptnames\fP | |
7225 | are enabled, non-zero otherwise. When setting or unsetting options, | |
cce855bc | 7226 | the return status is zero unless an \fIoptname\fP is not a valid shell |
ccc6cda3 JA |
7227 | option. |
7228 | .PP | |
7229 | The list of \fBshopt\fP options is: | |
7230 | .if t .sp .5v | |
7231 | .if n .sp 1v | |
7232 | .PD 0 | |
7233 | .TP 8 | |
7234 | .B cdable_vars | |
7235 | If set, an argument to the | |
7236 | .B cd | |
7237 | builtin command that | |
7238 | is not a directory is assumed to be the name of a variable whose | |
7239 | value is the directory to change to. | |
7240 | .TP 8 | |
7241 | .B cdspell | |
7242 | If set, minor errors in the spelling of a directory component in a | |
7243 | .B cd | |
7244 | command will be corrected. | |
7245 | The errors checked for are transposed characters, | |
7246 | a missing character, and one character too many. | |
7247 | If a correction is found, the corrected file name is printed, | |
7248 | and the command proceeds. | |
d166f048 | 7249 | This option is only used by interactive shells. |
ccc6cda3 JA |
7250 | .TP 8 |
7251 | .B checkhash | |
7252 | If set, \fBbash\fP checks that a command found in the hash | |
7253 | table exists before trying to execute it. If a hashed command no | |
7254 | longer exists, a normal path search is performed. | |
7255 | .TP 8 | |
7256 | .B checkwinsize | |
7257 | If set, \fBbash\fP checks the window size after each command | |
7258 | and, if necessary, updates the values of | |
7259 | .SM | |
7260 | .B LINES | |
7261 | and | |
7262 | .SM | |
7263 | .BR COLUMNS . | |
7264 | .TP 8 | |
7265 | .B cmdhist | |
7266 | If set, | |
7267 | .B bash | |
7268 | attempts to save all lines of a multiple-line | |
7269 | command in the same history entry. This allows | |
7270 | easy re-editing of multi-line commands. | |
7271 | .TP 8 | |
7272 | .B dotglob | |
7273 | If set, | |
7274 | .B bash | |
7275 | includes filenames beginning with a `.' in the results of pathname | |
7276 | expansion. | |
7277 | .TP 8 | |
7278 | .B execfail | |
7279 | If set, a non-interactive shell will not exit if | |
7280 | it cannot execute the file specified as an argument to the | |
7281 | .B exec | |
7282 | builtin command. An interactive shell does not exit if | |
7283 | .B exec | |
7284 | fails. | |
7285 | .TP 8 | |
7286 | .B expand_aliases | |
7287 | If set, aliases are expanded as described above under | |
7288 | .SM | |
7289 | .BR ALIASES . | |
7290 | This option is enabled by default for interactive shells. | |
7291 | .TP 8 | |
cce855bc JA |
7292 | .B extglob |
7293 | If set, the extended pattern matching features described above under | |
7294 | \fBPathname Expansion\fP are enabled. | |
7295 | .TP 8 | |
ccc6cda3 JA |
7296 | .B histappend |
7297 | If set, the history list is appended to the file named by the value | |
7298 | of the | |
7299 | .B HISTFILE | |
7300 | variable when the shell exits, rather than overwriting the file. | |
7301 | .TP 8 | |
7302 | .B histreedit | |
7303 | If set, and | |
7304 | .B readline | |
7305 | is being used, a user is given the opportunity to re-edit a | |
7306 | failed history substitution. | |
7307 | .TP 8 | |
7308 | .B histverify | |
7309 | If set, and | |
7310 | .B readline | |
7311 | is being used, the results of history substitution are not immediately | |
7312 | passed to the shell parser. Instead, the resulting line is loaded into | |
7313 | the \fBreadline\fP editing buffer, allowing further modification. | |
7314 | .TP 8 | |
7315 | .B hostcomplete | |
7316 | If set, and | |
7317 | .B readline | |
cce855bc JA |
7318 | is being used, \fBbash\fP will attempt to perform hostname completion when a |
7319 | word containing a \fB@\fP is being completed (see | |
ccc6cda3 JA |
7320 | .B Completing |
7321 | under | |
7322 | .SM | |
7323 | .B READLINE | |
7324 | above). | |
7325 | This is enabled by default. | |
7326 | .TP 8 | |
cce855bc JA |
7327 | .B huponexit |
7328 | If set, \fBbash\fP will send | |
7329 | .SM | |
7330 | .B SIGHUP | |
7331 | to all jobs when an interactive login shell exits. | |
7332 | .TP 8 | |
ccc6cda3 JA |
7333 | .B interactive_comments |
7334 | If set, allow a word beginning with | |
7335 | .B # | |
7336 | to cause that word and all remaining characters on that | |
7337 | line to be ignored in an interactive shell (see | |
7338 | .SM | |
7339 | .B COMMENTS | |
7340 | above). This option is enabled by default. | |
7341 | .TP 8 | |
7342 | .B lithist | |
7343 | If set, and the | |
7344 | .B cmdhist | |
7345 | option is enabled, multi-line commands are saved to the history with | |
7346 | embedded newlines rather than using semicolon separators where possible. | |
7347 | .TP 8 | |
7348 | .B mailwarn | |
7349 | If set, and a file that \fBbash\fP is checking for mail has been | |
7350 | accessed since the last time it was checked, the message ``The mail in | |
7351 | \fImailfile\fP has been read'' is displayed. | |
7352 | .TP 8 | |
bb70624e JA |
7353 | .B no_empty_cmd_completion |
7354 | If set, and | |
7355 | .B readline | |
7356 | is being used, | |
7357 | .B bash | |
7358 | will not attempt to search the \fBPATH\fP for possible completions when | |
7359 | completion is attempted on an empty line. | |
7360 | .TP 8 | |
cce855bc JA |
7361 | .B nocaseglob |
7362 | If set, | |
7363 | .B bash | |
7364 | matches filenames in a case\-insensitive fashion when performing pathname | |
7365 | expansion (see | |
7366 | .B Pathname Expansion | |
7367 | above). | |
7368 | .TP 8 | |
ccc6cda3 JA |
7369 | .B nullglob |
7370 | If set, | |
7371 | .B bash | |
7372 | allows patterns which match no | |
7373 | files (see | |
7374 | .B Pathname Expansion | |
7375 | above) | |
7376 | to expand to a null string, rather than themselves. | |
7377 | .TP 8 | |
bb70624e JA |
7378 | .B progcomp |
7379 | If set, the programmable completion facilities (see | |
7380 | \fBProgrammable Completion\fP above) are enabled. | |
7381 | This option is enabled by default. | |
7382 | .TP 8 | |
ccc6cda3 JA |
7383 | .B promptvars |
7384 | If set, prompt strings undergo variable and parameter expansion after | |
7385 | being expanded as described in | |
7386 | .SM | |
7387 | .B PROMPTING | |
7388 | above. This option is enabled by default. | |
7389 | .TP 8 | |
b72432fd JA |
7390 | .B restricted_shell |
7391 | The shell sets this option if it is started in restricted mode (see | |
7392 | .SM | |
7393 | .B "RESTRICTED SHELL" | |
7394 | below). | |
7395 | The value may not be changed. | |
7396 | This is not reset when the startup files are executed, allowing | |
7397 | the startup files to discover whether or not a shell is restricted. | |
7398 | .TP 8 | |
ccc6cda3 JA |
7399 | .B shift_verbose |
7400 | If set, the | |
7401 | .B shift | |
7402 | builtin prints an error message when the shift count exceeds the | |
7403 | number of positional parameters. | |
7404 | .TP 8 | |
7405 | .B sourcepath | |
7406 | If set, the | |
7407 | \fBsource\fP (\fB.\fP) builtin uses the value of | |
7408 | .SM | |
7409 | .B PATH | |
7410 | to find the directory containing the file supplied as an argument. | |
cce855bc | 7411 | This option is enabled by default. |
bb70624e JA |
7412 | .TP 8 |
7413 | .B xpg_echo | |
7414 | If set, the \fBecho\fP builtin expands backslash-escape sequences | |
7415 | by default. | |
ccc6cda3 | 7416 | .RE |
726f6388 JA |
7417 | .TP |
7418 | \fBsuspend\fP [\fB\-f\fP] | |
7419 | Suspend the execution of this shell until it receives a | |
7420 | .SM | |
7421 | .B SIGCONT | |
7422 | signal. The | |
7423 | .B \-f | |
7424 | option says not to complain if this is | |
7425 | a login shell; just suspend anyway. The return status is 0 unless | |
7426 | the shell is a login shell and | |
7427 | .B \-f | |
7428 | is not supplied, or if job control is not enabled. | |
7429 | .TP | |
7430 | .PD 0 | |
7431 | \fBtest\fP \fIexpr\fP | |
7432 | .TP | |
7433 | \fB[\fP \fIexpr\fP \fB]\fP | |
ccc6cda3 | 7434 | Return a status of 0 or 1 depending on |
726f6388 JA |
7435 | the evaluation of the conditional expression |
7436 | .IR expr . | |
cce855bc JA |
7437 | Each operator and operand must be a separate argument. |
7438 | Expressions are composed of the primaries described above under | |
7439 | .SM | |
7440 | .BR "CONDITIONAL EXPRESSIONS" . | |
7441 | .if t .sp 0.5 | |
7442 | .if n .sp 1 | |
7443 | Expressions may be combined using the following operators, listed | |
7444 | in decreasing order of precedence. | |
726f6388 JA |
7445 | .RS |
7446 | .PD 0 | |
7447 | .TP | |
726f6388 JA |
7448 | .B ! \fIexpr\fP |
7449 | True if | |
7450 | .I expr | |
7451 | is false. | |
7452 | .TP | |
cce855bc JA |
7453 | .B ( \fIexpr\fP ) |
7454 | Returns the value of \fIexpr\fP. | |
7455 | This may be used to override the normal precedence of operators. | |
7456 | .TP | |
726f6388 JA |
7457 | \fIexpr1\fP \-\fBa\fP \fIexpr2\fP |
7458 | True if both | |
7459 | .I expr1 | |
cce855bc | 7460 | and |
726f6388 JA |
7461 | .I expr2 |
7462 | are true. | |
7463 | .TP | |
7464 | \fIexpr1\fP \-\fBo\fP \fIexpr2\fP | |
7465 | True if either | |
7466 | .I expr1 | |
cce855bc | 7467 | or |
726f6388 JA |
7468 | .I expr2 |
7469 | is true. | |
cce855bc JA |
7470 | .PD |
7471 | .PP | |
7472 | \fBtest\fP and \fB[\fP evaluate conditional | |
7473 | expressions using a set of rules based on the number of arguments. | |
7474 | .if t .sp 0.5 | |
7475 | .if n .sp 1 | |
7476 | .PD 0 | |
726f6388 | 7477 | .TP |
cce855bc JA |
7478 | 0 arguments |
7479 | The expression is false. | |
7480 | .TP | |
7481 | 1 argument | |
7482 | The expression is true if and only if the argument is not null. | |
7483 | .TP | |
7484 | 2 arguments | |
7485 | If the first argument is \fB!\fP, the expression is true if and | |
7486 | only if the second argument is null. | |
7487 | If the first argument is one of the unary conditional operators listed above | |
7488 | under | |
726f6388 | 7489 | .SM |
cce855bc JA |
7490 | .BR "CONDITIONAL EXPRESSIONS" , |
7491 | the expression is true if the unary test is true. | |
7492 | If the first argument is not a valid unary conditional operator, the expression | |
7493 | is false. | |
7494 | .TP | |
7495 | 3 arguments | |
7496 | If the second argument is one of the binary conditional operators listed above | |
7497 | under | |
7498 | .SM | |
7499 | .BR "CONDITIONAL EXPRESSIONS" , | |
7500 | the result of the expression is the result of the binary test using | |
7501 | the first and third arguments as operands. | |
7502 | If the first argument is \fB!\fP, the value is the negation of | |
7503 | the two-argument test using the second and third arguments. | |
7504 | If the first argument is exactly \fB(\fP and the third argument is | |
7505 | exactly \fB)\fP, the result is the one-argument test of the second | |
7506 | argument. | |
7507 | Otherwise, the expression is false. | |
7508 | The \fB\-a\fP and \fB\-o\fP operators are considered binary operators | |
7509 | in this case. | |
7510 | .TP | |
7511 | 4 arguments | |
7512 | If the first argument is \fB!\fP, the result is the negation of | |
7513 | the three-argument expression composed of the remaining arguments. | |
7514 | Otherwise, the expression is parsed and evaluated according to | |
7515 | precedence using the rules listed above. | |
7516 | .TP | |
7517 | 5 or more arguments | |
7518 | The expression is parsed and evaluated according to precedence | |
7519 | using the rules listed above. | |
726f6388 | 7520 | .RE |
cce855bc | 7521 | .PD |
726f6388 JA |
7522 | .TP |
7523 | .B times | |
7524 | Print the accumulated user and system times for the shell and | |
7525 | for processes run from the shell. The return status is 0. | |
7526 | .TP | |
d166f048 | 7527 | \fBtrap\fP [\fB\-lp\fP] [\fIarg\fP] [\fIsigspec\fP ...] |
726f6388 JA |
7528 | The command |
7529 | .I arg | |
7530 | is to be read and executed when the shell receives | |
7531 | signal(s) | |
7532 | .IR sigspec . | |
7533 | If | |
7534 | .I arg | |
7535 | is absent or | |
7536 | .BR \- , | |
7537 | all specified signals are | |
7538 | reset to their original values (the values they had | |
d166f048 JA |
7539 | upon entrance to the shell). |
7540 | If | |
726f6388 | 7541 | .I arg |
d166f048 JA |
7542 | is the null string the signal specified by each |
7543 | .I sigspec | |
7544 | is ignored by the shell and by the commands it invokes. | |
ccc6cda3 JA |
7545 | If |
7546 | .I arg | |
bb70624e | 7547 | is not present and |
ccc6cda3 | 7548 | .B \-p |
bb70624e | 7549 | has been supplied, then the trap commands associated with each |
ccc6cda3 | 7550 | .I sigspec |
bb70624e JA |
7551 | are displayed. |
7552 | If no arguments are supplied or if only | |
ccc6cda3 JA |
7553 | .B \-p |
7554 | is given, | |
7555 | .B trap | |
7556 | prints the list of commands associated with each signal number. | |
d166f048 | 7557 | Each |
726f6388 JA |
7558 | .I sigspec |
7559 | is either | |
d166f048 JA |
7560 | a signal name defined in <\fIsignal.h\fP>, or a signal number. |
7561 | If a | |
726f6388 JA |
7562 | .I sigspec |
7563 | is | |
7564 | .SM | |
7565 | .B EXIT | |
7566 | (0) the command | |
7567 | .I arg | |
d166f048 | 7568 | is executed on exit from the shell. If a |
ccc6cda3 JA |
7569 | .I sigspec |
7570 | is | |
7571 | .SM | |
7572 | .BR DEBUG , | |
7573 | the command | |
7574 | .I arg | |
7575 | is executed after every \fIsimple command\fP (see | |
7576 | .SM | |
7577 | .B SHELL GRAMMAR | |
7578 | above). | |
7579 | The | |
726f6388 | 7580 | .B \-l |
ccc6cda3 JA |
7581 | option causes the shell to print a list of signal names and |
7582 | their corresponding numbers. | |
726f6388 JA |
7583 | Signals ignored upon entry to the shell cannot be trapped or reset. |
7584 | Trapped signals are reset to their original values in a child | |
d166f048 JA |
7585 | process when it is created. |
7586 | The return status is false if any | |
ccc6cda3 JA |
7587 | .I sigspec |
7588 | is invalid; otherwise | |
726f6388 JA |
7589 | .B trap |
7590 | returns true. | |
7591 | .TP | |
cce855bc | 7592 | \fBtype\fP [\fB\-atp\fP] \fIname\fP [\fIname\fP ...] |
726f6388 JA |
7593 | With no options, |
7594 | indicate how each | |
7595 | .I name | |
7596 | would be interpreted if used as a command name. | |
7597 | If the | |
cce855bc JA |
7598 | .B \-t |
7599 | option is used, | |
726f6388 | 7600 | .B type |
ccc6cda3 | 7601 | prints a string which is one of |
726f6388 JA |
7602 | .IR alias , |
7603 | .IR keyword , | |
7604 | .IR function , | |
7605 | .IR builtin , | |
7606 | or | |
7607 | .I file | |
7608 | if | |
7609 | .I name | |
7610 | is an alias, shell reserved word, function, builtin, or disk file, | |
ccc6cda3 JA |
7611 | respectively. |
7612 | If the | |
7613 | .I name | |
7614 | is not found, then nothing is printed, and an exit status of false | |
7615 | is returned. | |
726f6388 | 7616 | If the |
cce855bc JA |
7617 | .B \-p |
7618 | option is used, | |
726f6388 JA |
7619 | .B type |
7620 | either returns the name of the disk file | |
7621 | that would be executed if | |
7622 | .I name | |
7623 | were specified as a command name, | |
cce855bc | 7624 | or nothing if \f(CWtype -t name\fP |
726f6388 JA |
7625 | would not return |
7626 | .IR file . | |
7627 | If a command is hashed, | |
cce855bc | 7628 | .B \-p |
726f6388 JA |
7629 | prints the hashed value, not necessarily the file that appears |
7630 | first in | |
7631 | .SM | |
7632 | .BR PATH . | |
7633 | If the | |
cce855bc JA |
7634 | .B \-a |
7635 | option is used, | |
726f6388 JA |
7636 | .B type |
7637 | prints all of the places that contain | |
7638 | an executable named | |
7639 | .IR name . | |
7640 | This includes aliases and functions, | |
7641 | if and only if the | |
cce855bc JA |
7642 | .B \-p |
7643 | option is not also used. | |
726f6388 JA |
7644 | The table of hashed commands is not consulted |
7645 | when using | |
cce855bc | 7646 | .BR \-a . |
726f6388 JA |
7647 | .B type |
7648 | returns true if any of the arguments are found, false if | |
7649 | none are found. | |
7650 | .TP | |
ccc6cda3 JA |
7651 | \fBulimit\fP [\fB\-SHacdflmnpstuv\fP [\fIlimit\fP]] |
7652 | Provides control over the resources available to the shell and to | |
726f6388 JA |
7653 | processes started by it, on systems that allow such control. The |
7654 | value of | |
7655 | .I limit | |
7656 | can be a number in the unit specified for the resource, or the | |
7657 | value | |
7658 | .BR unlimited . | |
ccc6cda3 | 7659 | The \fB\-H\fP and \fB\-S\fP options specify that the hard or soft limit is |
726f6388 JA |
7660 | set for the given resource. A hard limit cannot be increased once it |
7661 | is set; a soft limit may be increased up to the value of the hard limit. | |
ccc6cda3 JA |
7662 | If neither \fB\-H\fP nor \fB\-S\fP is specified, both the soft and hard |
7663 | limits are set. | |
7664 | If | |
726f6388 JA |
7665 | .I limit |
7666 | is omitted, the current value of the soft limit of the resource is | |
ccc6cda3 JA |
7667 | printed, unless the \fB\-H\fP option is given. When more than one |
7668 | resource is specified, the limit name and unit are printed before the value. | |
726f6388 JA |
7669 | Other options are interpreted as follows: |
7670 | .RS | |
7671 | .PD 0 | |
7672 | .TP | |
7673 | .B \-a | |
ccc6cda3 | 7674 | All current limits are reported |
726f6388 JA |
7675 | .TP |
7676 | .B \-c | |
ccc6cda3 | 7677 | The maximum size of core files created |
726f6388 JA |
7678 | .TP |
7679 | .B \-d | |
ccc6cda3 | 7680 | The maximum size of a process's data segment |
726f6388 JA |
7681 | .TP |
7682 | .B \-f | |
ccc6cda3 | 7683 | The maximum size of files created by the shell |
726f6388 | 7684 | .TP |
ccc6cda3 JA |
7685 | .B \-l |
7686 | The maximum size that may be locked into memory | |
726f6388 | 7687 | .TP |
ccc6cda3 JA |
7688 | .B \-m |
7689 | The maximum resident set size | |
726f6388 | 7690 | .TP |
ccc6cda3 JA |
7691 | .B \-n |
7692 | The maximum number of open file descriptors (most systems do not | |
7693 | allow this value to be set) | |
726f6388 JA |
7694 | .TP |
7695 | .B \-p | |
ccc6cda3 | 7696 | The pipe size in 512-byte blocks (this may not be set) |
726f6388 | 7697 | .TP |
ccc6cda3 JA |
7698 | .B \-s |
7699 | The maximum stack size | |
7700 | .TP | |
7701 | .B \-t | |
7702 | The maximum amount of cpu time in seconds | |
726f6388 JA |
7703 | .TP |
7704 | .B \-u | |
ccc6cda3 | 7705 | The maximum number of processes available to a single user |
726f6388 JA |
7706 | .TP |
7707 | .B \-v | |
7708 | The maximum amount of virtual memory available to the shell | |
7709 | .PD | |
7710 | .PP | |
ccc6cda3 | 7711 | If |
726f6388 JA |
7712 | .I limit |
7713 | is given, it is the new value of the specified resource (the | |
7714 | .B \-a | |
7715 | option is display only). | |
7716 | If no option is given, then | |
7717 | .B \-f | |
7718 | is assumed. Values are in 1024-byte increments, except for | |
7719 | .BR \-t , | |
7720 | which is in seconds, | |
7721 | .BR \-p , | |
7722 | which is in units of 512-byte blocks, | |
7723 | and | |
7724 | .B \-n | |
7725 | and | |
7726 | .BR \-u , | |
7727 | which are unscaled values. The return status is 0 | |
cce855bc | 7728 | unless an invalid option is encountered, a non-numeric argument |
726f6388 JA |
7729 | other than \fBunlimited\fP is supplied as \fIlimit\fP, or an |
7730 | error occurs while setting a new limit. | |
7731 | .RE | |
7732 | .TP | |
cce855bc | 7733 | \fBumask\fP [\fB\-p\fP] [\fB\-S\fP] [\fImode\fP] |
726f6388 JA |
7734 | The user file-creation mask is set to |
7735 | .IR mode . | |
7736 | If | |
7737 | .I mode | |
7738 | begins with a digit, it | |
7739 | is interpreted as an octal number; otherwise | |
7740 | it is interpreted as a symbolic mode mask similar | |
7741 | to that accepted by | |
7742 | .IR chmod (1). | |
7743 | If | |
7744 | .I mode | |
bb70624e | 7745 | is omitted, the current value of the mask is printed. |
ccc6cda3 | 7746 | The |
726f6388 JA |
7747 | .B \-S |
7748 | option causes the mask to be printed in symbolic form; the | |
7749 | default output is an octal number. | |
cce855bc JA |
7750 | If the |
7751 | .B \-p | |
7752 | option is supplied, and | |
7753 | .I mode | |
7754 | is omitted, the output is in a form that may be reused as input. | |
ccc6cda3 | 7755 | The return status is 0 if the mode was successfully changed or if |
726f6388 JA |
7756 | no \fImode\fP argument was supplied, and false otherwise. |
7757 | .TP | |
7758 | \fBunalias\fP [\-\fBa\fP] [\fIname\fP ...] | |
bb70624e | 7759 | Remove each \fIname\fP from the list of defined aliases. If |
726f6388 JA |
7760 | .B \-a |
7761 | is supplied, all alias definitions are removed. The return | |
7762 | value is true unless a supplied | |
7763 | .I name | |
7764 | is not a defined alias. | |
7765 | .TP | |
7766 | \fBunset\fP [\-\fBfv\fP] [\fIname\fP ...] | |
7767 | For each | |
7768 | .IR name , | |
ccc6cda3 JA |
7769 | remove the corresponding variable or function. |
7770 | If no options are supplied, or the | |
7771 | .B \-v | |
7772 | option is given, each | |
7773 | .I name | |
7774 | refers to a shell variable. | |
7775 | Read-only variables may not be unset. | |
7776 | If | |
726f6388 | 7777 | .B \-f |
ccc6cda3 JA |
7778 | is specifed, |
7779 | each | |
7780 | .I name | |
7781 | refers to a shell function, and the function definition | |
7782 | is removed. | |
7783 | Each unset variable or function is removed from the environment | |
7784 | passed to subsequent commands. | |
7785 | If any of | |
726f6388 JA |
7786 | .SM |
7787 | .BR RANDOM , | |
7788 | .SM | |
7789 | .BR SECONDS , | |
7790 | .SM | |
7791 | .BR LINENO , | |
ccc6cda3 JA |
7792 | .SM |
7793 | .BR HISTCMD , | |
bb70624e JA |
7794 | .SM |
7795 | .BR FUNCNAME , | |
7796 | .SM | |
7797 | .BR GROUPS , | |
726f6388 JA |
7798 | or |
7799 | .SM | |
ccc6cda3 | 7800 | .B DIRSTACK |
726f6388 JA |
7801 | are unset, they lose their special properties, even if they are |
7802 | subsequently reset. The exit status is true unless a | |
7803 | .I name | |
ccc6cda3 | 7804 | does not exist or is readonly. |
726f6388 JA |
7805 | .TP |
7806 | \fBwait\fP [\fIn\fP] | |
7807 | Wait for the specified process and return its termination | |
7808 | status. | |
7809 | .I n | |
7810 | may be a process | |
7811 | ID or a job specification; if a job spec is given, all processes | |
7812 | in that job's pipeline are waited for. If | |
7813 | .I n | |
7814 | is not given, all currently active child processes | |
7815 | are waited for, and the return status is zero. If | |
7816 | .I n | |
ccc6cda3 | 7817 | specifies a non-existent process or job, the return status is |
726f6388 JA |
7818 | 127. Otherwise, the return status is the exit status of the last |
7819 | process or job waited for. | |
7820 | .\" bash_builtins | |
7821 | .if \n(zZ=1 .ig zZ | |
ccc6cda3 | 7822 | .SH "RESTRICTED SHELL" |
bb70624e JA |
7823 | .\" rbash.1 |
7824 | .zY | |
726f6388 | 7825 | .PP |
ccc6cda3 | 7826 | If |
726f6388 | 7827 | .B bash |
ccc6cda3 JA |
7828 | is started with the name |
7829 | .BR rbash , | |
7830 | or the | |
7831 | .B \-r | |
7832 | option is supplied at invocation, | |
7833 | the shell becomes restricted. | |
7834 | A restricted shell is used to | |
7835 | set up an environment more controlled than the standard shell. | |
7836 | It behaves identically to | |
7837 | .B bash | |
cce855bc | 7838 | with the exception that the following are disallowed or not performed: |
ccc6cda3 JA |
7839 | .IP \(bu |
7840 | changing directories with \fBcd\fP | |
7841 | .IP \(bu | |
7842 | setting or unsetting the values of | |
b72432fd JA |
7843 | .BR SHELL , |
7844 | .BR PATH , | |
7845 | .BR ENV , | |
ccc6cda3 | 7846 | or |
b72432fd | 7847 | .B BASH_ENV |
ccc6cda3 JA |
7848 | .IP \(bu |
7849 | specifying command names containing | |
7850 | .B / | |
7851 | .IP \(bu | |
7852 | specifying a file name containing a | |
7853 | .B / | |
7854 | as an argument to the | |
7855 | .B . | |
7856 | builtin command | |
7857 | .IP \(bu | |
bb70624e JA |
7858 | Specifying a filename containing a slash as an argument to the |
7859 | .B \-p | |
7860 | option to the | |
7861 | .B hash | |
7862 | builtin command | |
7863 | .IP \(bu | |
ccc6cda3 JA |
7864 | importing function definitions from the shell environment at startup |
7865 | .IP \(bu | |
cce855bc JA |
7866 | parsing the value of \fBSHELLOPTS\fP from the shell environment at startup |
7867 | .IP \(bu | |
ccc6cda3 JA |
7868 | redirecting output using the >, >|, <>, >&, &>, and >> redirection operators |
7869 | .IP \(bu | |
7870 | using the | |
7871 | .B exec | |
7872 | builtin command to replace the shell with another command | |
7873 | .IP \(bu | |
7874 | adding or deleting builtin commands with the | |
7875 | .B \-f | |
726f6388 | 7876 | and |
ccc6cda3 JA |
7877 | .B \-d |
7878 | options to the | |
7879 | .B enable | |
7880 | builtin command | |
7881 | .IP \(bu | |
7882 | specifying the | |
7883 | .B \-p | |
7884 | option to the | |
7885 | .B command | |
7886 | builtin command | |
7887 | .IP \(bu | |
7888 | turning off restricted mode with | |
cce855bc | 7889 | \fBset +r\fP or \fBset +o restricted\fP. |
726f6388 | 7890 | .PP |
ccc6cda3 JA |
7891 | These restrictions are enforced after any startup files are read. |
7892 | .PP | |
7893 | When a command that is found to be a shell script is executed (see | |
7894 | .SM | |
7895 | .B "COMMAND EXECUTION" | |
7896 | above), | |
7897 | .B rbash | |
7898 | turns off any restrictions in the shell spawned to execute the | |
7899 | script. | |
bb70624e JA |
7900 | .\" end of rbash.1 |
7901 | .if \n(zY=1 .ig zY | |
726f6388 JA |
7902 | .SH "SEE ALSO" |
7903 | .PD 0 | |
7904 | .TP | |
bb70624e | 7905 | \fIBash Reference Manual\fP, Brian Fox and Chet Ramey |
726f6388 JA |
7906 | .TP |
7907 | \fIThe Gnu Readline Library\fP, Brian Fox and Chet Ramey | |
7908 | .TP | |
7909 | \fIThe Gnu History Library\fP, Brian Fox and Chet Ramey | |
7910 | .TP | |
726f6388 JA |
7911 | \fIPortable Operating System Interface (POSIX) Part 2: Shell and Utilities\fP, IEEE |
7912 | .TP | |
7913 | \fIsh\fP(1), \fIksh\fP(1), \fIcsh\fP(1) | |
7914 | .TP | |
7915 | \fIemacs\fP(1), \fIvi\fP(1) | |
7916 | .TP | |
7917 | \fIreadline\fP(3) | |
7918 | .PD | |
7919 | .SH FILES | |
7920 | .PD 0 | |
7921 | .TP | |
7922 | .FN /bin/bash | |
7923 | The \fBbash\fP executable | |
7924 | .TP | |
7925 | .FN /etc/profile | |
7926 | The systemwide initialization file, executed for login shells | |
7927 | .TP | |
7928 | .FN ~/.bash_profile | |
7929 | The personal initialization file, executed for login shells | |
7930 | .TP | |
7931 | .FN ~/.bashrc | |
7932 | The individual per-interactive-shell startup file | |
7933 | .TP | |
b72432fd JA |
7934 | .FN ~/.bash_logout |
7935 | The individual login shell cleanup file, executed when a login shell exits | |
7936 | .TP | |
726f6388 JA |
7937 | .FN ~/.inputrc |
7938 | Individual \fIreadline\fP initialization file | |
7939 | .PD | |
7940 | .SH AUTHORS | |
ccc6cda3 | 7941 | Brian Fox, Free Software Foundation |
726f6388 | 7942 | .br |
bb70624e | 7943 | bfox@gnu.org |
726f6388 JA |
7944 | .PP |
7945 | Chet Ramey, Case Western Reserve University | |
7946 | .br | |
7947 | chet@ins.CWRU.Edu | |
7948 | .SH BUG REPORTS | |
7949 | If you find a bug in | |
7950 | .B bash, | |
7951 | you should report it. But first, you should | |
7952 | make sure that it really is a bug, and that it appears in the latest | |
7953 | version of | |
7954 | .B bash | |
7955 | that you have. | |
7956 | .PP | |
7957 | Once you have determined that a bug actually exists, use the | |
7958 | .I bashbug | |
7959 | command to submit a bug report. | |
d166f048 | 7960 | If you have a fix, you are encouraged to mail that as well! |
726f6388 | 7961 | Suggestions and `philosophical' bug reports may be mailed |
cce855bc | 7962 | to \fIbug-bash@gnu.org\fP or posted to the Usenet |
726f6388 JA |
7963 | newsgroup |
7964 | .BR gnu.bash.bug . | |
7965 | .PP | |
7966 | ALL bug reports should include: | |
7967 | .PP | |
7968 | .PD 0 | |
7969 | .TP 20 | |
7970 | The version number of \fBbash\fR | |
7971 | .TP | |
7972 | The hardware and operating system | |
7973 | .TP | |
7974 | The compiler used to compile | |
7975 | .TP | |
7976 | A description of the bug behaviour | |
7977 | .TP | |
7978 | A short script or `recipe' which exercises the bug | |
7979 | .PD | |
7980 | .PP | |
7981 | .I bashbug | |
7982 | inserts the first three items automatically into the template | |
7983 | it provides for filing a bug report. | |
7984 | .PP | |
7985 | Comments and bug reports concerning | |
7986 | this manual page should be directed to | |
7987 | .IR chet@ins.CWRU.Edu . | |
7988 | .SH BUGS | |
7989 | .PP | |
7990 | It's too big and too slow. | |
7991 | .PP | |
7992 | There are some subtle differences between | |
7993 | .B bash | |
7994 | and traditional versions of | |
7995 | .BR sh , | |
7996 | mostly because of the | |
7997 | .SM | |
7998 | .B POSIX | |
7999 | specification. | |
8000 | .PP | |
8001 | Aliases are confusing in some uses. | |
ccc6cda3 JA |
8002 | .PP |
8003 | Shell builtin commands and functions are not stoppable/restartable. | |
8004 | .PP | |
8005 | Compound commands and command sequences of the form `a ; b ; c' | |
8006 | are not handled gracefully when process suspension is attempted. | |
8007 | When a process is stopped, the shell immediately executes the next | |
8008 | command in the sequence. | |
8009 | It suffices to place the sequence of commands between | |
8010 | parentheses to force it into a subshell, which may be stopped as | |
8011 | a unit. | |
8012 | .PP | |
8013 | Commands inside of \fB$(\fP...\fB)\fP command substitution are not | |
8014 | parsed until substitution is attempted. This will delay error | |
8015 | reporting until some time after the command is entered. | |
8016 | .PP | |
8017 | Array variables may not (yet) be exported. | |
726f6388 | 8018 | .zZ |
bb70624e | 8019 | .zY |