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1 | <HTML><HEAD> |
2 | <TITLE>BASH(1) Manual Page</TITLE> | |
3 | </HEAD> | |
4 | <BODY><TABLE WIDTH=100%> | |
5 | <TR> | |
6 | <TH ALIGN=LEFT width=33%>BASH(1)<TH ALIGN=CENTER width=33%>2008 December 29<TH ALIGN=RIGHT width=33%>BASH(1) | |
7 | </TR> | |
8 | </TABLE> | |
9 | <BR><A HREF="#index">Index</A> | |
10 | <HR> | |
11 | ||
12 | ||
13 | ||
14 | ||
15 | ||
16 | ||
17 | ||
18 | ||
19 | ||
20 | ||
21 | ||
22 | ||
23 | ||
24 | ||
25 | ||
26 | ||
27 | ||
28 | ||
29 | ||
30 | <A NAME="lbAB"> </A> | |
31 | <H3>NAME</H3> | |
32 | ||
33 | bash - GNU Bourne-Again SHell | |
34 | <A NAME="lbAC"> </A> | |
35 | <H3>SYNOPSIS</H3> | |
36 | ||
37 | <B>bash</B> | |
38 | ||
39 | [options] | |
40 | [file] | |
41 | <A NAME="lbAD"> </A> | |
42 | <H3>COPYRIGHT</H3> | |
43 | ||
44 | ||
45 | Bash is Copyright © 1989-2009 by the Free Software Foundation, Inc. | |
46 | <A NAME="lbAE"> </A> | |
47 | <H3>DESCRIPTION</H3> | |
48 | ||
49 | <B>Bash</B> | |
50 | ||
51 | is an <B>sh</B>-compatible command language interpreter that | |
52 | executes commands read from the standard input or from a file. | |
53 | <B>Bash</B> | |
54 | ||
55 | also incorporates useful features from the <I>Korn</I> and <I>C</I> | |
56 | shells (<B>ksh</B> and <B>csh</B>). | |
57 | <P> | |
58 | ||
59 | <B>Bash</B> | |
60 | ||
61 | is intended to be a conformant implementation of the | |
62 | Shell and Utilities portion of the IEEE POSIX specification | |
63 | (IEEE Standard 1003.1). | |
64 | <B>Bash</B> | |
65 | ||
66 | can be configured to be POSIX-conformant by default. | |
67 | <A NAME="lbAF"> </A> | |
68 | <H3>OPTIONS</H3> | |
69 | ||
70 | In addition to the single-character shell options documented in the | |
71 | description of the <B>set</B> builtin command, <B>bash</B> | |
72 | interprets the following options when it is invoked: | |
73 | <P> | |
74 | ||
75 | ||
76 | <DL COMPACT> | |
77 | <DT><B>-c</B><I> string</I> | |
78 | ||
79 | <DD> | |
80 | If the | |
81 | <B>-c</B> | |
82 | ||
83 | option is present, then commands are read from | |
84 | <I>string</I>. | |
85 | ||
86 | If there are arguments after the | |
87 | <I>string</I>, | |
88 | ||
89 | they are assigned to the positional parameters, starting with | |
90 | <B>$0</B>. | |
91 | ||
92 | <DT><B>-i</B> | |
93 | ||
94 | <DD> | |
95 | If the | |
96 | <B>-i</B> | |
97 | ||
98 | option is present, the shell is | |
99 | <I>interactive</I>. | |
100 | ||
101 | <DT><B>-l</B> | |
102 | ||
103 | <DD> | |
104 | Make | |
105 | <B>bash</B> | |
106 | ||
107 | act as if it had been invoked as a login shell (see | |
108 | <FONT SIZE=-1><B>INVOCATION</B> | |
109 | ||
110 | </FONT> | |
111 | below). | |
112 | <DT><B>-r</B> | |
113 | ||
114 | <DD> | |
115 | If the | |
116 | <B>-r</B> | |
117 | ||
118 | option is present, the shell becomes | |
119 | <I>restricted</I> | |
120 | ||
121 | (see | |
122 | <FONT SIZE=-1><B>RESTRICTED SHELL</B> | |
123 | ||
124 | </FONT> | |
125 | below). | |
126 | <DT><B>-s</B> | |
127 | ||
128 | <DD> | |
129 | If the | |
130 | <B>-s</B> | |
131 | ||
132 | option is present, or if no arguments remain after option | |
133 | processing, then commands are read from the standard input. | |
134 | This option allows the positional parameters to be set | |
135 | when invoking an interactive shell. | |
136 | <DT><B>-D</B> | |
137 | ||
138 | <DD> | |
139 | A list of all double-quoted strings preceded by <B>$</B> | |
140 | is printed on the standard output. | |
141 | These are the strings that | |
142 | are subject to language translation when the current locale | |
143 | is not <B>C</B> or <B>POSIX</B>. | |
144 | This implies the <B>-n</B> option; no commands will be executed. | |
145 | <DT><B>[-+]O [</B><I>shopt_option</I>] | |
146 | ||
147 | <DD> | |
148 | <I>shopt_option</I> is one of the shell options accepted by the | |
149 | <B>shopt</B> builtin (see | |
150 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
151 | ||
152 | </FONT> | |
153 | below). | |
154 | If <I>shopt_option</I> is present, <B>-O</B> sets the value of that option; | |
155 | <B>+O</B> unsets it. | |
156 | If <I>shopt_option</I> is not supplied, the names and values of the shell | |
157 | options accepted by <B>shopt</B> are printed on the standard output. | |
158 | If the invocation option is <B>+O</B>, the output is displayed in a format | |
159 | that may be reused as input. | |
160 | <DT><B>--</B> | |
161 | ||
162 | <DD> | |
163 | A | |
164 | <B>--</B> | |
165 | ||
166 | signals the end of options and disables further option processing. | |
167 | Any arguments after the | |
168 | <B>--</B> | |
169 | ||
170 | are treated as filenames and arguments. An argument of | |
171 | <B>-</B> | |
172 | ||
173 | is equivalent to <B>--</B>. | |
174 | ||
175 | </DL> | |
176 | <P> | |
177 | ||
178 | <B>Bash</B> | |
179 | ||
180 | also interprets a number of multi-character options. | |
181 | These options must appear on the command line before the | |
182 | single-character options to be recognized. | |
183 | <P> | |
184 | ||
185 | ||
186 | <DL COMPACT> | |
187 | <DT><B>--debugger</B> | |
188 | ||
189 | <DD> | |
190 | Arrange for the debugger profile to be executed before the shell | |
191 | starts. | |
192 | Turns on extended debugging mode (see the description of the | |
193 | <B>extdebug</B> | |
194 | ||
195 | option to the | |
196 | <B>shopt</B> | |
197 | ||
198 | builtin below) | |
199 | and shell function tracing (see the description of the | |
200 | <B>-o functrace</B> option to the | |
201 | <B>set</B> | |
202 | ||
203 | builtin below). | |
204 | <DT><B>--dump-po-strings</B> | |
205 | ||
206 | <DD> | |
207 | Equivalent to <B>-D</B>, but the output is in the GNU <I>gettext</I> | |
208 | <B>po</B> (portable object) file format. | |
209 | <DT><B>--dump-strings</B> | |
210 | ||
211 | <DD> | |
212 | Equivalent to <B>-D</B>. | |
213 | <DT><B>--help</B> | |
214 | ||
215 | <DD> | |
216 | Display a usage message on standard output and exit successfully. | |
217 | <DT><B>--init-file</B> <I>file</I><DD> | |
218 | ||
219 | <DT><B>--rcfile</B> <I>file</I><DD> | |
220 | ||
221 | Execute commands from | |
222 | <I>file</I> | |
223 | ||
224 | instead of the standard personal initialization file | |
225 | <A HREF="file:~/.bashrc"><I>~/.bashrc</I></A> | |
226 | ||
227 | if the shell is interactive (see | |
228 | <FONT SIZE=-1><B>INVOCATION</B> | |
229 | ||
230 | </FONT> | |
231 | below). | |
232 | <DT><B>--login</B> | |
233 | ||
234 | <DD> | |
235 | Equivalent to <B>-l</B>. | |
236 | <DT><B>--noediting</B> | |
237 | ||
238 | <DD> | |
239 | Do not use the GNU | |
240 | <B>readline</B> | |
241 | ||
242 | library to read command lines when the shell is interactive. | |
243 | <DT><B>--noprofile</B> | |
244 | ||
245 | <DD> | |
246 | Do not read either the system-wide startup file | |
247 | ||
248 | <A HREF="file:/etc/profile"><I>/etc/profile</I></A> | |
249 | ||
250 | or any of the personal initialization files | |
251 | <A HREF="file:~/.bash_profile"><I>~/.bash_profile</I></A>, | |
252 | ||
253 | <A HREF="file:~/.bash_login"><I>~/.bash_login</I></A>, | |
254 | ||
255 | or | |
256 | <A HREF="file:~/.profile"><I>~/.profile</I></A>. | |
257 | ||
258 | By default, | |
259 | <B>bash</B> | |
260 | ||
261 | reads these files when it is invoked as a login shell (see | |
262 | <FONT SIZE=-1><B>INVOCATION</B> | |
263 | ||
264 | </FONT> | |
265 | below). | |
266 | <DT><B>--norc</B> | |
267 | ||
268 | <DD> | |
269 | Do not read and execute the personal initialization file | |
270 | <A HREF="file:~/.bashrc"><I>~/.bashrc</I></A> | |
271 | ||
272 | if the shell is interactive. | |
273 | This option is on by default if the shell is invoked as | |
274 | <B>sh</B>. | |
275 | ||
276 | <DT><B>--posix</B> | |
277 | ||
278 | <DD> | |
279 | Change the behavior of <B>bash</B> where the default operation differs | |
280 | from the POSIX standard to match the standard (<I>posix mode</I>). | |
281 | <DT><B>--restricted</B> | |
282 | ||
283 | <DD> | |
284 | The shell becomes restricted (see | |
285 | <FONT SIZE=-1><B>RESTRICTED SHELL</B> | |
286 | ||
287 | </FONT> | |
288 | below). | |
289 | <DT><B>--verbose</B> | |
290 | ||
291 | <DD> | |
292 | Equivalent to <B>-v</B>. | |
293 | <DT><B>--version</B> | |
294 | ||
295 | <DD> | |
296 | Show version information for this instance of | |
297 | <B>bash</B> | |
298 | ||
299 | on the standard output and exit successfully. | |
300 | ||
301 | </DL> | |
302 | <A NAME="lbAG"> </A> | |
303 | <H3>ARGUMENTS</H3> | |
304 | ||
305 | If arguments remain after option processing, and neither the | |
306 | <B>-c</B> | |
307 | ||
308 | nor the | |
309 | <B>-s</B> | |
310 | ||
311 | option has been supplied, the first argument is assumed to | |
312 | be the name of a file containing shell commands. | |
313 | If | |
314 | <B>bash</B> | |
315 | ||
316 | is invoked in this fashion, | |
317 | <B>$0</B> | |
318 | ||
319 | is set to the name of the file, and the positional parameters | |
320 | are set to the remaining arguments. | |
321 | <B>Bash</B> | |
322 | ||
323 | reads and executes commands from this file, then exits. | |
324 | <B>Bash</B>'s exit status is the exit status of the last command | |
325 | executed in the script. | |
326 | If no commands are executed, the exit status is 0. | |
327 | An attempt is first made to open the file in the current directory, and, | |
328 | if no file is found, then the shell searches the directories in | |
329 | <FONT SIZE=-1><B>PATH</B> | |
330 | ||
331 | </FONT> | |
332 | for the script. | |
333 | <A NAME="lbAH"> </A> | |
334 | <H3>INVOCATION</H3> | |
335 | ||
336 | A <I>login shell</I> is one whose first character of argument zero is a | |
337 | <B>-</B>, | |
338 | ||
339 | or one started with the | |
340 | <B>--login</B> | |
341 | ||
342 | option. | |
343 | <P> | |
344 | ||
345 | An <I>interactive</I> shell is one started without non-option arguments | |
346 | and without the | |
347 | <B>-c</B> | |
348 | ||
349 | option | |
350 | whose standard input and error are | |
351 | both connected to terminals (as determined by | |
352 | <I>isatty</I>(3)), | |
353 | ||
354 | or one started with the | |
355 | <B>-i</B> | |
356 | ||
357 | option. | |
358 | <FONT SIZE=-1><B>PS1</B> | |
359 | ||
360 | </FONT> | |
361 | is set and | |
362 | <B>$-</B> | |
363 | ||
364 | includes | |
365 | <B>i</B> | |
366 | ||
367 | if | |
368 | <B>bash</B> | |
369 | ||
370 | is interactive, | |
371 | allowing a shell script or a startup file to test this state. | |
372 | <P> | |
373 | ||
374 | The following paragraphs describe how | |
375 | <B>bash</B> | |
376 | ||
377 | executes its startup files. | |
378 | If any of the files exist but cannot be read, | |
379 | <B>bash</B> | |
380 | ||
381 | reports an error. | |
382 | Tildes are expanded in file names as described below under | |
383 | <B>Tilde Expansion</B> | |
384 | ||
385 | in the | |
386 | <FONT SIZE=-1><B>EXPANSION</B> | |
387 | ||
388 | </FONT> | |
389 | section. | |
390 | <P> | |
391 | ||
392 | When | |
393 | <B>bash</B> | |
394 | ||
395 | is invoked as an interactive login shell, or as a non-interactive shell | |
396 | with the <B>--login</B> option, it first reads and | |
397 | executes commands from the file <A HREF="file:/etc/profile"><I>/etc/profile</I></A>, if that | |
398 | file exists. | |
399 | After reading that file, it looks for <A HREF="file:~/.bash_profile"><I>~/.bash_profile</I></A>, | |
400 | <A HREF="file:~/.bash_login"><I>~/.bash_login</I></A>, and <A HREF="file:~/.profile"><I>~/.profile</I></A>, in that order, and reads | |
401 | and executes commands from the first one that exists and is readable. | |
402 | The | |
403 | <B>--noprofile</B> | |
404 | ||
405 | option may be used when the shell is started to inhibit this behavior. | |
406 | <P> | |
407 | ||
408 | When a login shell exits, | |
409 | <B>bash</B> | |
410 | ||
411 | reads and executes commands from the file <A HREF="file:~/.bash_logout"><I>~/.bash_logout</I></A>, if it | |
412 | exists. | |
413 | <P> | |
414 | ||
415 | When an interactive shell that is not a login shell is started, | |
416 | <B>bash</B> | |
417 | ||
418 | reads and executes commands from <A HREF="file:~/.bashrc"><I>~/.bashrc</I></A>, if that file exists. | |
419 | This may be inhibited by using the | |
420 | <B>--norc</B> | |
421 | ||
422 | option. | |
423 | The <B>--rcfile</B> <I>file</I> option will force | |
424 | <B>bash</B> | |
425 | ||
426 | to read and execute commands from <I>file</I> instead of <A HREF="file:~/.bashrc"><I>~/.bashrc</I></A>. | |
427 | <P> | |
428 | ||
429 | When | |
430 | <B>bash</B> | |
431 | ||
432 | is started non-interactively, to run a shell script, for example, it | |
433 | looks for the variable | |
434 | <FONT SIZE=-1><B>BASH_ENV</B> | |
435 | ||
436 | </FONT> | |
437 | in the environment, expands its value if it appears there, and uses the | |
438 | expanded value as the name of a file to read and execute. | |
439 | <B>Bash</B> | |
440 | ||
441 | behaves as if the following command were executed: | |
442 | <P> | |
443 | <DL COMPACT><DT><DD> | |
444 | <TT>if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi</TT> | |
445 | ||
446 | </DL> | |
447 | ||
448 | <P> | |
449 | but the value of the | |
450 | <FONT SIZE=-1><B>PATH</B> | |
451 | ||
452 | </FONT> | |
453 | variable is not used to search for the file name. | |
454 | <P> | |
455 | ||
456 | If | |
457 | <B>bash</B> | |
458 | ||
459 | is invoked with the name | |
460 | <B>sh</B>, | |
461 | ||
462 | it tries to mimic the startup behavior of historical versions of | |
463 | <B>sh</B> | |
464 | ||
465 | as closely as possible, | |
466 | while conforming to the POSIX standard as well. | |
467 | When invoked as an interactive login shell, or a non-interactive | |
468 | shell with the <B>--login</B> option, it first attempts to | |
469 | read and execute commands from | |
470 | <A HREF="file:/etc/profile"><I>/etc/profile</I></A> | |
471 | ||
472 | and | |
473 | <A HREF="file:~/.profile"><I>~/.profile</I></A>, | |
474 | ||
475 | in that order. | |
476 | The | |
477 | <B>--noprofile</B> | |
478 | ||
479 | option may be used to inhibit this behavior. | |
480 | When invoked as an interactive shell with the name | |
481 | <B>sh</B>, | |
482 | ||
483 | <B>bash</B> | |
484 | ||
485 | looks for the variable | |
486 | <FONT SIZE=-1><B>ENV</B>, | |
487 | ||
488 | </FONT> | |
489 | expands its value if it is defined, and uses the | |
490 | expanded value as the name of a file to read and execute. | |
491 | Since a shell invoked as | |
492 | <B>sh</B> | |
493 | ||
494 | does not attempt to read and execute commands from any other startup | |
495 | files, the | |
496 | <B>--rcfile</B> | |
497 | ||
498 | option has no effect. | |
499 | A non-interactive shell invoked with the name | |
500 | <B>sh</B> | |
501 | ||
502 | does not attempt to read any other startup files. | |
503 | When invoked as | |
504 | <B>sh</B>, | |
505 | ||
506 | <B>bash</B> | |
507 | ||
508 | enters | |
509 | <I>posix</I> | |
510 | ||
511 | mode after the startup files are read. | |
512 | <P> | |
513 | ||
514 | When | |
515 | <B>bash</B> | |
516 | ||
517 | is started in | |
518 | <I>posix</I> | |
519 | ||
520 | mode, as with the | |
521 | <B>--posix</B> | |
522 | ||
523 | command line option, it follows the POSIX standard for startup files. | |
524 | In this mode, interactive shells expand the | |
525 | <FONT SIZE=-1><B>ENV</B> | |
526 | ||
527 | </FONT> | |
528 | variable and commands are read and executed from the file | |
529 | whose name is the expanded value. | |
530 | No other startup files are read. | |
531 | <P> | |
532 | ||
533 | <B>Bash</B> | |
534 | ||
535 | attempts to determine when it is being run with its standard input | |
536 | connected to a a network connection, as if by the remote shell | |
537 | daemon, usually <I>rshd</I>, or the secure shell daemon <I>sshd</I>. | |
538 | If | |
539 | <B>bash</B> | |
540 | ||
541 | determines it is being run in this fashion, it reads and executes | |
542 | commands from <A HREF="file:~/.bashrc"><I>~/.bashrc</I></A>, if that file exists and is readable. | |
543 | It will not do this if invoked as <B>sh</B>. | |
544 | The | |
545 | <B>--norc</B> | |
546 | ||
547 | option may be used to inhibit this behavior, and the | |
548 | <B>--rcfile</B> | |
549 | ||
550 | option may be used to force another file to be read, but | |
551 | <I>rshd</I> does not generally invoke the shell with those options | |
552 | or allow them to be specified. | |
553 | <P> | |
554 | ||
555 | If the shell is started with the effective user (group) id not equal to the | |
556 | real user (group) id, and the <B>-p</B> option is not supplied, no startup | |
557 | files are read, shell functions are not inherited from the environment, the | |
558 | <FONT SIZE=-1><B>SHELLOPTS</B> | |
559 | ||
560 | </FONT> | |
561 | variable, if it appears in the environment, is ignored, | |
562 | and the effective user id is set to the real user id. | |
563 | If the <B>-p</B> option is supplied at invocation, the startup behavior is | |
564 | the same, but the effective user id is not reset. | |
565 | <A NAME="lbAI"> </A> | |
566 | <H3>DEFINITIONS</H3> | |
567 | ||
568 | <P> | |
569 | ||
570 | The following definitions are used throughout the rest of this | |
571 | document. | |
572 | ||
573 | <DL COMPACT> | |
574 | <DT><B>blank </B> | |
575 | ||
576 | <DD> | |
577 | A space or tab. | |
578 | <DT><B>word</B> | |
579 | ||
580 | <DD> | |
581 | A sequence of characters considered as a single unit by the shell. | |
582 | Also known as a | |
583 | <B>token</B>. | |
584 | ||
585 | <DT><B>name</B> | |
586 | ||
587 | <DD> | |
588 | A | |
589 | <I>word</I> | |
590 | ||
591 | consisting only of alphanumeric characters and underscores, and | |
592 | beginning with an alphabetic character or an underscore. Also | |
593 | referred to as an | |
594 | <B>identifier</B>. | |
595 | ||
596 | <DT><B>metacharacter</B> | |
597 | ||
598 | <DD> | |
599 | A character that, when unquoted, separates words. One of the following: | |
600 | <BR> | |
601 | ||
602 | <DL COMPACT><DT><DD> | |
603 | <P> | |
604 | ||
605 | <B>| & ; ( ) < > space tab</B> | |
606 | ||
607 | </DL> | |
608 | ||
609 | </DL> | |
610 | <P> | |
611 | ||
612 | <DL COMPACT> | |
613 | <DT><B>control operator</B> | |
614 | ||
615 | <DD> | |
616 | A <I>token</I> that performs a control function. It is one of the following | |
617 | symbols: | |
618 | <DL COMPACT><DT><DD> | |
619 | <P> | |
620 | ||
621 | <B>|| & && ; ;; ( ) | |& <newline></B> | |
622 | ||
623 | </DL> | |
624 | ||
625 | ||
626 | </DL> | |
627 | <A NAME="lbAJ"> </A> | |
628 | <H3>RESERVED WORDS</H3> | |
629 | ||
630 | <I>Reserved words</I> are words that have a special meaning to the shell. | |
631 | The following words are recognized as reserved when unquoted and either | |
632 | the first word of a simple command (see | |
633 | <FONT SIZE=-1><B>SHELL GRAMMAR</B> | |
634 | ||
635 | </FONT> | |
636 | below) or the third word of a | |
637 | <B>case </B> | |
638 | ||
639 | or | |
640 | <B>for</B> | |
641 | ||
642 | command: | |
643 | <DL COMPACT><DT><DD> | |
644 | ||
645 | <P> | |
646 | ||
647 | <B> | |
648 | </B> | |
649 | ||
650 | ! case do done elif else esac fi for function if in select then until while { } time [[ ]] | |
651 | </DL> | |
652 | ||
653 | ||
654 | <A NAME="lbAK"> </A> | |
655 | <H3>SHELL GRAMMAR</H3> | |
656 | ||
657 | <A NAME="lbAL"> </A> | |
658 | <H4>Simple Commands</H4> | |
659 | ||
660 | <P> | |
661 | ||
662 | A <I>simple command</I> is a sequence of optional variable assignments | |
663 | followed by <B>blank</B>-separated words and redirections, and | |
664 | terminated by a <I>control operator</I>. The first word | |
665 | specifies the command to be executed, and is passed as argument zero. | |
666 | The remaining words are passed as arguments to the invoked command. | |
667 | <P> | |
668 | ||
669 | The return value of a <I>simple command</I> is its exit status, or | |
670 | 128+<I>n</I> if the command is terminated by signal | |
671 | <I>n</I>. | |
672 | ||
673 | <A NAME="lbAM"> </A> | |
674 | <H4>Pipelines</H4> | |
675 | ||
676 | <P> | |
677 | ||
678 | A <I>pipeline</I> is a sequence of one or more commands separated by | |
679 | one of the control operators | |
680 | <B>|</B> | |
681 | ||
682 | or <B>|&</B>. | |
683 | The format for a pipeline is: | |
684 | <DL COMPACT><DT><DD> | |
685 | <P> | |
686 | ||
687 | [<B>time</B> [<B>-p</B>]] [ ! ] <I>command</I> [ [<B>|</B>|<B>|&</B>] <I>command2</I> ... ] | |
688 | </DL> | |
689 | ||
690 | <P> | |
691 | ||
692 | The standard output of | |
693 | <I>command</I> | |
694 | ||
695 | is connected via a pipe to the standard input of | |
696 | <I>command2</I>. | |
697 | ||
698 | This connection is performed before any redirections specified by the | |
699 | command (see | |
700 | <FONT SIZE=-1><B>REDIRECTION</B> | |
701 | ||
702 | </FONT> | |
703 | below). | |
704 | If <B>|&</B> is used, the standard error of <I>command</I> is connected to | |
705 | <I>command2</I>'s standard input through the pipe; it is shorthand for | |
706 | <B>2>&1 |</B>. | |
707 | This implicit redirection of the standard error is performed after any | |
708 | redirections specified by the command. | |
709 | <P> | |
710 | ||
711 | The return status of a pipeline is the exit status of the last | |
712 | command, unless the <B>pipefail</B> option is enabled. | |
713 | If <B>pipefail</B> is enabled, the pipeline's return status is the | |
714 | value of the last (rightmost) command to exit with a non-zero status, | |
715 | or zero if all commands exit successfully. | |
716 | If the reserved word | |
717 | <B>!</B> | |
718 | ||
719 | precedes a pipeline, the exit status of that pipeline is the logical | |
720 | negation of the exit status as described above. | |
721 | The shell waits for all commands in the pipeline to | |
722 | terminate before returning a value. | |
723 | <P> | |
724 | ||
725 | If the | |
726 | <B>time</B> | |
727 | ||
728 | reserved word precedes a pipeline, the elapsed as well as user and | |
729 | system time consumed by its execution are reported when the pipeline | |
730 | terminates. | |
731 | The <B>-p</B> option changes the output format to that specified by POSIX. | |
732 | The | |
733 | <FONT SIZE=-1><B>TIMEFORMAT</B> | |
734 | ||
735 | </FONT> | |
736 | variable may be set to a format string that specifies how the timing | |
737 | information should be displayed; see the description of | |
738 | <FONT SIZE=-1><B>TIMEFORMAT</B> | |
739 | ||
740 | </FONT> | |
741 | under | |
742 | <B>Shell Variables</B> | |
743 | ||
744 | below. | |
745 | <P> | |
746 | ||
747 | Each command in a pipeline is executed as a separate process (i.e., in a | |
748 | subshell). | |
749 | <A NAME="lbAN"> </A> | |
750 | <H4>Lists</H4> | |
751 | ||
752 | <P> | |
753 | ||
754 | A <I>list</I> is a sequence of one or more pipelines separated by one | |
755 | of the operators | |
756 | <B>;</B>, | |
757 | ||
758 | <B>&</B>, | |
759 | ||
760 | <B>&&</B>, | |
761 | ||
762 | or | |
763 | <B>||</B>, | |
764 | ||
765 | and optionally terminated by one of | |
766 | <B>;</B>, | |
767 | ||
768 | <B>&</B>, | |
769 | ||
770 | or | |
771 | <B><newline></B>. | |
772 | ||
773 | <P> | |
774 | ||
775 | Of these list operators, | |
776 | <B>&&</B> | |
777 | ||
778 | and | |
779 | <B>||</B> | |
780 | ||
781 | have equal precedence, followed by | |
782 | <B>;</B> | |
783 | ||
784 | and | |
785 | <B>&</B>, | |
786 | ||
787 | which have equal precedence. | |
788 | <P> | |
789 | ||
790 | A sequence of one or more newlines may appear in a <I>list</I> instead | |
791 | of a semicolon to delimit commands. | |
792 | <P> | |
793 | ||
794 | If a command is terminated by the control operator | |
795 | <B>&</B>, | |
796 | ||
797 | the shell executes the command in the <I>background</I> | |
798 | in a subshell. The shell does not wait for the command to | |
799 | finish, and the return status is 0. Commands separated by a | |
800 | <B>;</B> | |
801 | ||
802 | are executed sequentially; the shell waits for each | |
803 | command to terminate in turn. The return status is the | |
804 | exit status of the last command executed. | |
805 | <P> | |
806 | ||
807 | AND and OR lists are sequences of one of more pipelines separated by the | |
808 | <B>&&</B> and <B>||</B> control operators, respectively. | |
809 | AND and OR lists are executed with left associativity. | |
810 | An AND list has the form | |
811 | <DL COMPACT><DT><DD> | |
812 | <P> | |
813 | ||
814 | <I>command1</I> <B>&&</B> <I>command2</I> | |
815 | </DL> | |
816 | ||
817 | <P> | |
818 | ||
819 | <I>command2</I> | |
820 | ||
821 | is executed if, and only if, | |
822 | <I>command1</I> | |
823 | ||
824 | returns an exit status of zero. | |
825 | <P> | |
826 | ||
827 | An OR list has the form | |
828 | <DL COMPACT><DT><DD> | |
829 | <P> | |
830 | ||
831 | <I>command1</I> <B>||</B> <I>command2</I> | |
832 | <P> | |
833 | ||
834 | </DL> | |
835 | ||
836 | <P> | |
837 | ||
838 | <I>command2</I> | |
839 | ||
840 | is executed if and only if | |
841 | <I>command1</I> | |
842 | ||
843 | returns a non-zero exit status. | |
844 | The return status of | |
845 | AND and OR lists is the exit status of the last command | |
846 | executed in the list. | |
847 | <A NAME="lbAO"> </A> | |
848 | <H4>Compound Commands</H4> | |
849 | ||
850 | <P> | |
851 | ||
852 | A <I>compound command</I> is one of the following: | |
853 | <DL COMPACT> | |
854 | <DT>(<I>list</I>)<DD> | |
855 | <I>list</I> is executed in a subshell environment (see | |
856 | <FONT SIZE=-1><B>COMMAND EXECUTION ENVIRONMENT</B></FONT> | |
857 | below). | |
858 | Variable assignments and builtin | |
859 | commands that affect the shell's environment do not remain in effect | |
860 | after the command completes. The return status is the exit status of | |
861 | <I>list</I>. | |
862 | <DT>{ <I>list</I>; }<DD> | |
863 | <I>list</I> is simply executed in the current shell environment. | |
864 | <I>list</I> must be terminated with a newline or semicolon. | |
865 | This is known as a <I>group command</I>. | |
866 | The return status is the exit status of | |
867 | <I>list</I>. | |
868 | Note that unlike the metacharacters <B>(</B> and <B>)</B>, <B>{</B> and | |
869 | <B>}</B> are <I>reserved words</I> and must occur where a reserved | |
870 | word is permitted to be recognized. Since they do not cause a word | |
871 | break, they must be separated from <I>list</I> by whitespace or another | |
872 | shell metacharacter. | |
873 | <DT>((<I>expression</I>))<DD> | |
874 | The <I>expression</I> is evaluated according to the rules described | |
875 | below under | |
876 | <FONT SIZE=-1><B>ARITHMETIC EVALUATION</B>. | |
877 | ||
878 | </FONT> | |
879 | If the value of the expression is non-zero, the return status is 0; | |
880 | otherwise the return status is 1. This is exactly equivalent to | |
881 | <B>let "</B><I>expression</I>". | |
882 | <DT><B>[[</B> <I>expression</I> <B>]]</B><DD> | |
883 | Return a status of 0 or 1 depending on the evaluation of | |
884 | the conditional expression <I>expression</I>. | |
885 | Expressions are composed of the primaries described below under | |
886 | <FONT SIZE=-1><B>CONDITIONAL EXPRESSIONS</B>. | |
887 | ||
888 | </FONT> | |
889 | Word splitting and pathname expansion are not performed on the words | |
890 | between the <B>[[</B> and <B>]]</B>; tilde expansion, parameter and | |
891 | variable expansion, arithmetic expansion, command substitution, process | |
892 | substitution, and quote removal are performed. | |
893 | Conditional operators such as <B>-f</B> must be unquoted to be recognized | |
894 | as primaries. | |
895 | <P> | |
896 | ||
897 | ||
898 | When the <B>==</B> and <B>!=</B> operators are used, the string to the | |
899 | right of the operator is considered a pattern and matched according | |
900 | to the rules described below under <B>Pattern Matching</B>. | |
901 | If the shell option | |
902 | <B>nocasematch</B> | |
903 | ||
904 | is enabled, the match is performed without regard to the case | |
905 | of alphabetic characters. | |
906 | The return value is 0 if the string matches (<B>==</B>) or does not match | |
907 | (<B>!=</B>) the pattern, and 1 otherwise. | |
908 | Any part of the pattern may be quoted to force it to be matched as a | |
909 | string. | |
910 | <P> | |
911 | ||
912 | ||
913 | An additional binary operator, <B>=~</B>, is available, with the same | |
914 | precedence as <B>==</B> and <B>!=</B>. | |
915 | When it is used, the string to the right of the operator is considered | |
916 | an extended regular expression and matched accordingly (as in <I>regex</I>(3)). | |
917 | The return value is 0 if the string matches | |
918 | the pattern, and 1 otherwise. | |
919 | If the regular expression is syntactically incorrect, the conditional | |
920 | expression's return value is 2. | |
921 | If the shell option | |
922 | <B>nocasematch</B> | |
923 | ||
924 | is enabled, the match is performed without regard to the case | |
925 | of alphabetic characters. | |
926 | Any part of the pattern may be quoted to force it to be matched as a | |
927 | string. | |
928 | Substrings matched by parenthesized subexpressions within the regular | |
929 | expression are saved in the array variable <B>BASH_REMATCH</B>. | |
930 | The element of <B>BASH_REMATCH</B> with index 0 is the portion of the string | |
931 | matching the entire regular expression. | |
932 | The element of <B>BASH_REMATCH</B> with index <I>n</I> is the portion of the | |
933 | string matching the <I>n</I>th parenthesized subexpression. | |
934 | <P> | |
935 | ||
936 | ||
937 | Expressions may be combined using the following operators, listed | |
938 | in decreasing order of precedence: | |
939 | <P> | |
940 | ||
941 | ||
942 | <DL COMPACT><DT><DD> | |
943 | ||
944 | <DL COMPACT> | |
945 | <DT><B>( </B><I>expression</I> ) | |
946 | ||
947 | <DD> | |
948 | Returns the value of <I>expression</I>. | |
949 | This may be used to override the normal precedence of operators. | |
950 | <DT><B>! </B><I>expression</I> | |
951 | ||
952 | <DD> | |
953 | True if | |
954 | <I>expression</I> | |
955 | ||
956 | is false. | |
957 | <DT><I>expression1</I> <B>&&</B> <I>expression2</I><DD> | |
958 | True if both | |
959 | <I>expression1</I> | |
960 | ||
961 | and | |
962 | <I>expression2</I> | |
963 | ||
964 | are true. | |
965 | <DT><I>expression1</I> <B>||</B> <I>expression2</I> | |
966 | <DD> | |
967 | ||
968 | True if either | |
969 | <I>expression1</I> | |
970 | ||
971 | or | |
972 | <I>expression2</I> | |
973 | ||
974 | is true. | |
975 | ||
976 | </DL> | |
977 | <P> | |
978 | ||
979 | The <B>&&</B> and | |
980 | <B>||</B> | |
981 | ||
982 | operators do not evaluate <I>expression2</I> if the value of | |
983 | <I>expression1</I> is sufficient to determine the return value of | |
984 | the entire conditional expression. | |
985 | </DL> | |
986 | ||
987 | <DT><B>for</B> <I>name</I> [ <B>in</B> <I>word</I> ] ; <B>do</B> <I>list</I> ; <B>done</B><DD> | |
988 | The list of words following <B>in</B> is expanded, generating a list | |
989 | of items. | |
990 | The variable <I>name</I> is set to each element of this list | |
991 | in turn, and <I>list</I> is executed each time. | |
992 | If the <B>in</B> <I>word</I> is omitted, the <B>for</B> command executes | |
993 | <I>list</I> once for each positional parameter that is set (see | |
994 | <FONT SIZE=-1><B>PARAMETERS</B> | |
995 | ||
996 | </FONT> | |
997 | below). | |
998 | The return status is the exit status of the last command that executes. | |
999 | If the expansion of the items following <B>in</B> results in an empty | |
1000 | list, no commands are executed, and the return status is 0. | |
1001 | <DT><B>for</B> (( <I>expr1</I> ; <I>expr2</I> ; <I>expr3</I> )) ; <B>do</B> <I>list</I> ; <B>done</B><DD> | |
1002 | First, the arithmetic expression <I>expr1</I> is evaluated according | |
1003 | to the rules described below under | |
1004 | <FONT SIZE=-1><B>ARITHMETIC EVALUATION</B>. | |
1005 | ||
1006 | </FONT> | |
1007 | The arithmetic expression <I>expr2</I> is then evaluated repeatedly | |
1008 | until it evaluates to zero. | |
1009 | Each time <I>expr2</I> evaluates to a non-zero value, <I>list</I> is | |
1010 | executed and the arithmetic expression <I>expr3</I> is evaluated. | |
1011 | If any expression is omitted, it behaves as if it evaluates to 1. | |
1012 | The return value is the exit status of the last command in <I>list</I> | |
1013 | that is executed, or false if any of the expressions is invalid. | |
1014 | <DT><B>select</B> <I>name</I> [ <B>in</B> <I>word</I> ] ; <B>do</B> <I>list</I> ; <B>done</B><DD> | |
1015 | The list of words following <B>in</B> is expanded, generating a list | |
1016 | of items. The set of expanded words is printed on the standard | |
1017 | error, each preceded by a number. If the <B>in</B> | |
1018 | <I>word</I> is omitted, the positional parameters are printed (see | |
1019 | <FONT SIZE=-1><B>PARAMETERS</B> | |
1020 | ||
1021 | </FONT> | |
1022 | below). The | |
1023 | <B>PS3</B> | |
1024 | ||
1025 | prompt is then displayed and a line read from the standard input. | |
1026 | If the line consists of a number corresponding to one of | |
1027 | the displayed words, then the value of | |
1028 | <I>name</I> | |
1029 | ||
1030 | is set to that word. If the line is empty, the words and prompt | |
1031 | are displayed again. If EOF is read, the command completes. Any | |
1032 | other value read causes | |
1033 | <I>name</I> | |
1034 | ||
1035 | to be set to null. The line read is saved in the variable | |
1036 | <B>REPLY</B>. | |
1037 | ||
1038 | The | |
1039 | <I>list</I> | |
1040 | ||
1041 | is executed after each selection until a | |
1042 | <B>break</B> | |
1043 | ||
1044 | command is executed. | |
1045 | The exit status of | |
1046 | <B>select</B> | |
1047 | ||
1048 | is the exit status of the last command executed in | |
1049 | <I>list</I>, | |
1050 | ||
1051 | or zero if no commands were executed. | |
1052 | <DT><B>case</B> <I>word</I> <B>in</B> [ [(] <I>pattern</I> [ <B>|</B> <I>pattern</I> ] | |
1053 | <DD> | |
1054 | A <B>case</B> command first expands <I>word</I>, and tries to match | |
1055 | it against each <I>pattern</I> in turn, using the same matching rules | |
1056 | as for pathname expansion (see | |
1057 | <B>Pathname Expansion</B> | |
1058 | ||
1059 | below). | |
1060 | The <I>word</I> is expanded using tilde | |
1061 | expansion, parameter and variable expansion, arithmetic substitution, | |
1062 | command substitution, process substitution and quote removal. | |
1063 | Each <I>pattern</I> examined is expanded using tilde | |
1064 | expansion, parameter and variable expansion, arithmetic substitution, | |
1065 | command substitution, and process substitution. | |
1066 | If the shell option | |
1067 | <B>nocasematch</B> | |
1068 | ||
1069 | is enabled, the match is performed without regard to the case | |
1070 | of alphabetic characters. | |
1071 | When a match is found, the corresponding <I>list</I> is executed. | |
1072 | If the <B>;;</B> operator is used, no subsequent matches are attempted after | |
1073 | the first pattern match. | |
1074 | Using <B>;&</B> in place of <B>;;</B> causes execution to continue with | |
1075 | the <I>list</I> associated with the next set of patterns. | |
1076 | Using <B>;;&</B> in place of <B>;;</B> causes the shell to test the next | |
1077 | pattern list in the statement, if any, and execute any associated <I>list</I> | |
1078 | on a successful match. | |
1079 | The exit status is zero if no | |
1080 | pattern matches. Otherwise, it is the exit status of the | |
1081 | last command executed in <I>list</I>. | |
1082 | <DT><B>if</B> <I>list</I>; <B>then</B> <I>list;</I> [ <B>elif</B> <I>list</I>; <B>then</B> <I>list</I>; ] ... [ <B>else</B> <I>list</I>; ] <B>fi</B><DD> | |
1083 | The | |
1084 | <B>if </B> | |
1085 | ||
1086 | <I>list</I> | |
1087 | ||
1088 | is executed. If its exit status is zero, the | |
1089 | <B>then</B> <I>list</I> is executed. Otherwise, each <B>elif</B> | |
1090 | <I>list</I> is executed in turn, and if its exit status is zero, | |
1091 | the corresponding <B>then</B> <I>list</I> is executed and the | |
1092 | command completes. Otherwise, the <B>else</B> <I>list</I> is | |
1093 | executed, if present. The exit status is the exit status of the | |
1094 | last command executed, or zero if no condition tested true. | |
1095 | <DT><B>while</B> <I>list</I>; <B>do</B> <I>list</I>; <B>done</B><DD> | |
1096 | ||
1097 | <DT><B>until</B> <I>list</I>; <B>do</B> <I>list</I>; <B>done</B><DD> | |
1098 | ||
1099 | The <B>while</B> command continuously executes the <B>do</B> | |
1100 | <I>list</I> as long as the last command in <I>list</I> returns | |
1101 | an exit status of zero. The <B>until</B> command is identical | |
1102 | to the <B>while</B> command, except that the test is negated; | |
1103 | the | |
1104 | <B>do</B> | |
1105 | ||
1106 | <I>list</I> | |
1107 | ||
1108 | is executed as long as the last command in | |
1109 | <I>list</I> | |
1110 | ||
1111 | returns a non-zero exit status. | |
1112 | The exit status of the <B>while</B> and <B>until</B> commands | |
1113 | is the exit status | |
1114 | of the last <B>do</B> <I>list</I> command executed, or zero if | |
1115 | none was executed. | |
1116 | </DL> | |
1117 | <A NAME="lbAP"> </A> | |
1118 | <H4>Coprocesses</H4> | |
1119 | ||
1120 | <P> | |
1121 | ||
1122 | A <I>coprocess</I> is a shell command preceded by the <B>coproc</B> reserved | |
1123 | word. | |
1124 | A coprocess is executed asynchronously in a subshell, as if the command | |
1125 | had been terminated with the <B>&</B> control operator, with a two-way pipe | |
1126 | established between the executing shell and the coprocess. | |
1127 | <P> | |
1128 | ||
1129 | The format for a coprocess is: | |
1130 | <DL COMPACT><DT><DD> | |
1131 | <P> | |
1132 | ||
1133 | <B>coproc</B> [<I>NAME</I>] <I>command</I> [<I>redirections</I>] | |
1134 | </DL> | |
1135 | ||
1136 | <P> | |
1137 | ||
1138 | This creates a coprocess named <I>NAME</I>. | |
1139 | If <I>NAME</I> is not supplied, the default name is <I>COPROC</I>. | |
1140 | <I>NAME</I> must not be supplied if <I>command</I> is a <I>simple | |
1141 | command</I> (see above); otherwise, it is interpreted as the first word | |
1142 | of the simple command. | |
1143 | When the coproc is executed, the shell creates an array variable (see | |
1144 | <B>Arrays</B> | |
1145 | ||
1146 | below) named <I>NAME</I> in the context of the executing shell. | |
1147 | The standard output of | |
1148 | <I>command</I> | |
1149 | ||
1150 | is connected via a pipe to a file descriptor in the executing shell, | |
1151 | and that file descriptor is assigned to <I>NAME</I>[0]. | |
1152 | The standard input of | |
1153 | <I>command</I> | |
1154 | ||
1155 | is connected via a pipe to a file descriptor in the executing shell, | |
1156 | and that file descriptor is assigned to <I>NAME</I>[1]. | |
1157 | This pipe is established before any redirections specified by the | |
1158 | command (see | |
1159 | <FONT SIZE=-1><B>REDIRECTION</B> | |
1160 | ||
1161 | </FONT> | |
1162 | below). | |
1163 | The file descriptors can be utilized as arguments to shell commands | |
1164 | and redirections using standard word expansions. | |
1165 | The process id of the shell spawned to execute the coprocess is | |
1166 | available as the value of the variable <I>NAME</I>_PID. | |
1167 | The <B>wait</B> | |
1168 | builtin command may be used to wait for the coprocess to terminate. | |
1169 | <P> | |
1170 | ||
1171 | The return status of a coprocess is the exit status of <I>command</I>. | |
1172 | <A NAME="lbAQ"> </A> | |
1173 | <H4>Shell Function Definitions</H4> | |
1174 | ||
1175 | <P> | |
1176 | ||
1177 | A shell function is an object that is called like a simple command and | |
1178 | executes a compound command with a new set of positional parameters. | |
1179 | Shell functions are declared as follows: | |
1180 | <DL COMPACT> | |
1181 | <DT>[ <B>function</B> ] <I>name</I> () <I>compound-command</I> [<I>redirection</I>]<DD> | |
1182 | This defines a function named <I>name</I>. | |
1183 | The reserved word <B>function</B> is optional. | |
1184 | If the <B>function</B> reserved word is supplied, the parentheses are optional. | |
1185 | The <I>body</I> of the function is the compound command | |
1186 | <I>compound-command </I> | |
1187 | ||
1188 | (see <B>Compound Commands</B> above). | |
1189 | That command is usually a <I>list</I> of commands between { and }, but | |
1190 | may be any command listed under <B>Compound Commands</B> above. | |
1191 | <I>compound-command</I> is executed whenever <I>name</I> is specified as the | |
1192 | name of a simple command. | |
1193 | Any redirections (see | |
1194 | <FONT SIZE=-1><B>REDIRECTION</B> | |
1195 | ||
1196 | </FONT> | |
1197 | below) specified when a function is defined are performed | |
1198 | when the function is executed. | |
1199 | The exit status of a function definition is zero unless a syntax error | |
1200 | occurs or a readonly function with the same name already exists. | |
1201 | When executed, the exit status of a function is the exit status of the | |
1202 | last command executed in the body. (See | |
1203 | <FONT SIZE=-1><B>FUNCTIONS</B> | |
1204 | ||
1205 | </FONT> | |
1206 | below.) | |
1207 | </DL> | |
1208 | <A NAME="lbAR"> </A> | |
1209 | <H3>COMMENTS</H3> | |
1210 | ||
1211 | In a non-interactive shell, or an interactive shell in which the | |
1212 | <B>interactive_comments</B> | |
1213 | ||
1214 | option to the | |
1215 | <B>shopt</B> | |
1216 | ||
1217 | builtin is enabled (see | |
1218 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
1219 | ||
1220 | </FONT> | |
1221 | below), a word beginning with | |
1222 | <B>#</B> | |
1223 | ||
1224 | causes that word and all remaining characters on that line to | |
1225 | be ignored. An interactive shell without the | |
1226 | <B>interactive_comments</B> | |
1227 | ||
1228 | option enabled does not allow comments. The | |
1229 | <B>interactive_comments</B> | |
1230 | ||
1231 | option is on by default in interactive shells. | |
1232 | <A NAME="lbAS"> </A> | |
1233 | <H3>QUOTING</H3> | |
1234 | ||
1235 | <I>Quoting</I> is used to remove the special meaning of certain | |
1236 | characters or words to the shell. Quoting can be used to | |
1237 | disable special treatment for special characters, to prevent | |
1238 | reserved words from being recognized as such, and to prevent | |
1239 | parameter expansion. | |
1240 | <P> | |
1241 | ||
1242 | Each of the <I>metacharacters</I> listed above under | |
1243 | <FONT SIZE=-1><B>DEFINITIONS</B> | |
1244 | ||
1245 | </FONT> | |
1246 | has special meaning to the shell and must be quoted if it is to | |
1247 | represent itself. | |
1248 | <P> | |
1249 | ||
1250 | When the command history expansion facilities are being used | |
1251 | (see | |
1252 | <FONT SIZE=-1><B>HISTORY EXPANSION</B> | |
1253 | ||
1254 | </FONT> | |
1255 | below), the | |
1256 | <I>history expansion</I> character, usually <B>!</B>, must be quoted | |
1257 | to prevent history expansion. | |
1258 | <P> | |
1259 | ||
1260 | There are three quoting mechanisms: the | |
1261 | <I>escape character</I>, | |
1262 | ||
1263 | single quotes, and double quotes. | |
1264 | <P> | |
1265 | ||
1266 | A non-quoted backslash (<B>\</B>) is the | |
1267 | <I>escape character</I>. | |
1268 | ||
1269 | It preserves the literal value of the next character that follows, | |
1270 | with the exception of <newline>. If a <B>\</B><newline> pair | |
1271 | appears, and the backslash is not itself quoted, the <B>\</B><newline> | |
1272 | is treated as a line continuation (that is, it is removed from the | |
1273 | input stream and effectively ignored). | |
1274 | <P> | |
1275 | ||
1276 | Enclosing characters in single quotes preserves the literal value | |
1277 | of each character within the quotes. A single quote may not occur | |
1278 | between single quotes, even when preceded by a backslash. | |
1279 | <P> | |
1280 | ||
1281 | Enclosing characters in double quotes preserves the literal value | |
1282 | of all characters within the quotes, with the exception of | |
1283 | <B>$</B>, | |
1284 | ||
1285 | <B>`</B>, | |
1286 | ||
1287 | <B>\</B>, | |
1288 | ||
1289 | and, when history expansion is enabled, | |
1290 | <B>!</B>. | |
1291 | ||
1292 | The characters | |
1293 | <B>$</B> | |
1294 | ||
1295 | and | |
1296 | <B>`</B> | |
1297 | ||
1298 | retain their special meaning within double quotes. The backslash | |
1299 | retains its special meaning only when followed by one of the following | |
1300 | characters: | |
1301 | <B>$</B>, | |
1302 | ||
1303 | <B>`</B>, | |
1304 | ||
1305 | <B>"</B>, | |
1306 | <B>\</B>, | |
1307 | ||
1308 | or | |
1309 | <B><newline></B>. | |
1310 | ||
1311 | A double quote may be quoted within double quotes by preceding it with | |
1312 | a backslash. | |
1313 | If enabled, history expansion will be performed unless an | |
1314 | <B>!</B> | |
1315 | ||
1316 | appearing in double quotes is escaped using a backslash. | |
1317 | The backslash preceding the | |
1318 | <B>!</B> | |
1319 | ||
1320 | is not removed. | |
1321 | <P> | |
1322 | ||
1323 | The special parameters | |
1324 | <B>*</B> | |
1325 | ||
1326 | and | |
1327 | <B>@</B> | |
1328 | ||
1329 | have special meaning when in double | |
1330 | quotes (see | |
1331 | <FONT SIZE=-1><B>PARAMETERS</B> | |
1332 | ||
1333 | </FONT> | |
1334 | below). | |
1335 | <P> | |
1336 | ||
1337 | Words of the form <B>$</B>aq<I>string</I>aq are treated specially. The | |
1338 | word expands to <I>string</I>, with backslash-escaped characters replaced | |
1339 | as specified by the ANSI C standard. Backslash escape sequences, if | |
1340 | present, are decoded as follows: | |
1341 | <DL COMPACT><DT><DD> | |
1342 | ||
1343 | <DL COMPACT> | |
1344 | <DT><B>\a</B> | |
1345 | ||
1346 | <DD> | |
1347 | alert (bell) | |
1348 | <DT><B>\b</B> | |
1349 | ||
1350 | <DD> | |
1351 | backspace | |
1352 | <DT><B>\e</B> | |
1353 | ||
1354 | <DD> | |
1355 | an escape character | |
1356 | <DT><B>\f</B> | |
1357 | ||
1358 | <DD> | |
1359 | form feed | |
1360 | <DT><B>\n</B> | |
1361 | ||
1362 | <DD> | |
1363 | new line | |
1364 | <DT><B>\r</B> | |
1365 | ||
1366 | <DD> | |
1367 | carriage return | |
1368 | <DT><B>\t</B> | |
1369 | ||
1370 | <DD> | |
1371 | horizontal tab | |
1372 | <DT><B>\v</B> | |
1373 | ||
1374 | <DD> | |
1375 | vertical tab | |
1376 | <DT><B>\\</B> | |
1377 | ||
1378 | <DD> | |
1379 | backslash | |
1380 | <DT><B>\aq</B> | |
1381 | ||
1382 | <DD> | |
1383 | single quote | |
1384 | <DT><B>\</B><I>nnn</I> | |
1385 | ||
1386 | <DD> | |
1387 | the eight-bit character whose value is the octal value <I>nnn</I> | |
1388 | (one to three digits) | |
1389 | <DT><B>\x</B><I>HH</I> | |
1390 | ||
1391 | <DD> | |
1392 | the eight-bit character whose value is the hexadecimal value <I>HH</I> | |
1393 | (one or two hex digits) | |
1394 | <DT><B>\c</B><I>x</I> | |
1395 | ||
1396 | <DD> | |
1397 | a control-<I>x</I> character | |
1398 | ||
1399 | </DL></DL> | |
1400 | ||
1401 | <P> | |
1402 | ||
1403 | The expanded result is single-quoted, as if the dollar sign had | |
1404 | not been present. | |
1405 | <P> | |
1406 | ||
1407 | A double-quoted string preceded by a dollar sign (<B>$</B>) will cause | |
1408 | the string to be translated according to the current locale. | |
1409 | If the current locale is <B>C</B> or <B>POSIX</B>, the dollar sign | |
1410 | is ignored. | |
1411 | If the string is translated and replaced, the replacement is | |
1412 | double-quoted. | |
1413 | <A NAME="lbAT"> </A> | |
1414 | <H3>PARAMETERS</H3> | |
1415 | ||
1416 | A | |
1417 | <I>parameter</I> | |
1418 | ||
1419 | is an entity that stores values. | |
1420 | It can be a | |
1421 | <I>name</I>, | |
1422 | ||
1423 | a number, or one of the special characters listed below under | |
1424 | <B>Special Parameters</B>. | |
1425 | ||
1426 | A | |
1427 | <I>variable</I> | |
1428 | ||
1429 | is a parameter denoted by a | |
1430 | <I>name</I>. | |
1431 | ||
1432 | A variable has a <I>value</I> and zero or more <I>attributes</I>. | |
1433 | Attributes are assigned using the | |
1434 | <B>declare</B> | |
1435 | ||
1436 | builtin command (see | |
1437 | <B>declare</B> | |
1438 | ||
1439 | below in | |
1440 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>). | |
1441 | ||
1442 | </FONT> | |
1443 | <P> | |
1444 | ||
1445 | A parameter is set if it has been assigned a value. The null string is | |
1446 | a valid value. Once a variable is set, it may be unset only by using | |
1447 | the | |
1448 | <B>unset</B> | |
1449 | ||
1450 | builtin command (see | |
1451 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
1452 | ||
1453 | </FONT> | |
1454 | below). | |
1455 | <P> | |
1456 | ||
1457 | A | |
1458 | <I>variable</I> | |
1459 | ||
1460 | may be assigned to by a statement of the form | |
1461 | <DL COMPACT><DT><DD> | |
1462 | <P> | |
1463 | ||
1464 | <I>name</I>=[<I>value</I>] | |
1465 | </DL> | |
1466 | ||
1467 | <P> | |
1468 | ||
1469 | If | |
1470 | <I>value</I> | |
1471 | ||
1472 | is not given, the variable is assigned the null string. All | |
1473 | <I>values</I> | |
1474 | ||
1475 | undergo tilde expansion, parameter and variable expansion, | |
1476 | command substitution, arithmetic expansion, and quote | |
1477 | removal (see | |
1478 | <FONT SIZE=-1><B>EXPANSION</B> | |
1479 | ||
1480 | </FONT> | |
1481 | below). If the variable has its | |
1482 | <B>integer</B> | |
1483 | ||
1484 | attribute set, then | |
1485 | <I>value</I> | |
1486 | ||
1487 | is evaluated as an arithmetic expression even if the $((...)) expansion is | |
1488 | not used (see | |
1489 | <B>Arithmetic Expansion</B> | |
1490 | ||
1491 | below). | |
1492 | Word splitting is not performed, with the exception | |
1493 | of <B>"$@"</B> as explained below under | |
1494 | <B>Special Parameters</B>. | |
1495 | ||
1496 | Pathname expansion is not performed. | |
1497 | Assignment statements may also appear as arguments to the | |
1498 | <B>alias</B>, | |
1499 | ||
1500 | <B>declare</B>, | |
1501 | ||
1502 | <B>typeset</B>, | |
1503 | ||
1504 | <B>export</B>, | |
1505 | ||
1506 | <B>readonly</B>, | |
1507 | ||
1508 | and | |
1509 | <B>local</B> | |
1510 | ||
1511 | builtin commands. | |
1512 | <P> | |
1513 | ||
1514 | In the context where an assignment statement is assigning a value | |
1515 | to a shell variable or array index, the += operator can be used to | |
1516 | append to or add to the variable's previous value. | |
1517 | When += is applied to a variable for which the integer attribute has been | |
1518 | set, <I>value</I> is evaluated as an arithmetic expression and added to the | |
1519 | variable's current value, which is also evaluated. | |
1520 | When += is applied to an array variable using compound assignment (see | |
1521 | <B>Arrays</B> | |
1522 | ||
1523 | below), the | |
1524 | variable's value is not unset (as it is when using =), and new values are | |
1525 | appended to the array beginning at one greater than the array's maximum index | |
1526 | (for indexed arrays) or added as additional key-value pairs in an | |
1527 | associative array. | |
1528 | When applied to a string-valued variable, <I>value</I> is expanded and | |
1529 | appended to the variable's value. | |
1530 | <A NAME="lbAU"> </A> | |
1531 | <H4>Positional Parameters</H4> | |
1532 | ||
1533 | <P> | |
1534 | ||
1535 | A | |
1536 | <I>positional parameter</I> | |
1537 | ||
1538 | is a parameter denoted by one or more | |
1539 | digits, other than the single digit 0. Positional parameters are | |
1540 | assigned from the shell's arguments when it is invoked, | |
1541 | and may be reassigned using the | |
1542 | <B>set</B> | |
1543 | ||
1544 | builtin command. Positional parameters may not be assigned to | |
1545 | with assignment statements. The positional parameters are | |
1546 | temporarily replaced when a shell function is executed (see | |
1547 | <FONT SIZE=-1><B>FUNCTIONS</B> | |
1548 | ||
1549 | </FONT> | |
1550 | below). | |
1551 | <P> | |
1552 | ||
1553 | When a positional parameter consisting of more than a single | |
1554 | digit is expanded, it must be enclosed in braces (see | |
1555 | <FONT SIZE=-1><B>EXPANSION</B> | |
1556 | ||
1557 | </FONT> | |
1558 | below). | |
1559 | <A NAME="lbAV"> </A> | |
1560 | <H4>Special Parameters</H4> | |
1561 | ||
1562 | <P> | |
1563 | ||
1564 | The shell treats several parameters specially. These parameters may | |
1565 | only be referenced; assignment to them is not allowed. | |
1566 | ||
1567 | <DL COMPACT> | |
1568 | <DT><B>*</B> | |
1569 | ||
1570 | <DD> | |
1571 | Expands to the positional parameters, starting from one. When the | |
1572 | expansion occurs within double quotes, it expands to a single word | |
1573 | with the value of each parameter separated by the first character | |
1574 | of the | |
1575 | <FONT SIZE=-1><B>IFS</B> | |
1576 | ||
1577 | </FONT> | |
1578 | special variable. That is, "<B>$*</B>" is equivalent | |
1579 | to "<B>$1</B><I>c</I><B>$2</B><I>c</I><B>...</B>", where | |
1580 | <I>c</I> | |
1581 | ||
1582 | is the first character of the value of the | |
1583 | <FONT SIZE=-1><B>IFS</B> | |
1584 | ||
1585 | </FONT> | |
1586 | variable. If | |
1587 | <FONT SIZE=-1><B>IFS</B> | |
1588 | ||
1589 | </FONT> | |
1590 | is unset, the parameters are separated by spaces. | |
1591 | If | |
1592 | <FONT SIZE=-1><B>IFS</B> | |
1593 | ||
1594 | </FONT> | |
1595 | is null, the parameters are joined without intervening separators. | |
1596 | <DT><B>@</B> | |
1597 | ||
1598 | <DD> | |
1599 | Expands to the positional parameters, starting from one. When the | |
1600 | expansion occurs within double quotes, each parameter expands to a | |
1601 | separate word. That is, "<B>$@</B>" is equivalent to | |
1602 | "<B>$1</B>" "<B>$2</B>" ... | |
1603 | If the double-quoted expansion occurs within a word, the expansion of | |
1604 | the first parameter is joined with the beginning part of the original | |
1605 | word, and the expansion of the last parameter is joined with the last | |
1606 | part of the original word. | |
1607 | When there are no positional parameters, "<B>$@</B>" and | |
1608 | <B>$@</B> | |
1609 | ||
1610 | expand to nothing (i.e., they are removed). | |
1611 | <DT><B>#</B> | |
1612 | ||
1613 | <DD> | |
1614 | Expands to the number of positional parameters in decimal. | |
1615 | <DT><B>?</B> | |
1616 | ||
1617 | <DD> | |
1618 | Expands to the exit status of the most recently executed foreground | |
1619 | pipeline. | |
1620 | <DT><B>-</B> | |
1621 | ||
1622 | <DD> | |
1623 | Expands to the current option flags as specified upon invocation, | |
1624 | by the | |
1625 | <B>set</B> | |
1626 | ||
1627 | builtin command, or those set by the shell itself | |
1628 | (such as the | |
1629 | <B>-i</B> | |
1630 | ||
1631 | option). | |
1632 | <DT><B>$</B> | |
1633 | ||
1634 | <DD> | |
1635 | Expands to the process ID of the shell. In a () subshell, it | |
1636 | expands to the process ID of the current shell, not the | |
1637 | subshell. | |
1638 | <DT><B>!</B> | |
1639 | ||
1640 | <DD> | |
1641 | Expands to the process ID of the most recently executed background | |
1642 | (asynchronous) command. | |
1643 | <DT><B>0</B> | |
1644 | ||
1645 | <DD> | |
1646 | Expands to the name of the shell or shell script. This is set at | |
1647 | shell initialization. If | |
1648 | <B>bash</B> | |
1649 | ||
1650 | is invoked with a file of commands, | |
1651 | <B>$0</B> | |
1652 | ||
1653 | is set to the name of that file. If | |
1654 | <B>bash</B> | |
1655 | ||
1656 | is started with the | |
1657 | <B>-c</B> | |
1658 | ||
1659 | option, then | |
1660 | <B>$0</B> | |
1661 | ||
1662 | is set to the first argument after the string to be | |
1663 | executed, if one is present. Otherwise, it is set | |
1664 | to the file name used to invoke | |
1665 | <B>bash</B>, | |
1666 | ||
1667 | as given by argument zero. | |
1668 | <DT><B>_</B> | |
1669 | ||
1670 | <DD> | |
1671 | At shell startup, set to the absolute pathname used to invoke the | |
1672 | shell or shell script being executed as passed in the environment | |
1673 | or argument list. | |
1674 | Subsequently, expands to the last argument to the previous command, | |
1675 | after expansion. | |
1676 | Also set to the full pathname used to invoke each command executed | |
1677 | and placed in the environment exported to that command. | |
1678 | When checking mail, this parameter holds the name of the mail file | |
1679 | currently being checked. | |
1680 | ||
1681 | </DL> | |
1682 | <A NAME="lbAW"> </A> | |
1683 | <H4>Shell Variables</H4> | |
1684 | ||
1685 | <P> | |
1686 | ||
1687 | The following variables are set by the shell: | |
1688 | <P> | |
1689 | ||
1690 | ||
1691 | <DL COMPACT> | |
1692 | <DT><B>BASH</B> | |
1693 | ||
1694 | <DD> | |
1695 | Expands to the full file name used to invoke this instance of | |
1696 | <B>bash</B>. | |
1697 | ||
1698 | <DT><B>BASHPID</B> | |
1699 | ||
1700 | <DD> | |
1701 | Expands to the process id of the current <B>bash</B> process. | |
1702 | This differs from <B>$$</B> under certain circumstances, such as subshells | |
1703 | that do not require <B>bash</B> to be re-initialized. | |
1704 | <DT><B>BASH_ALIASES</B> | |
1705 | ||
1706 | <DD> | |
1707 | An associative array variable whose members correspond to the internal | |
1708 | list of aliases as maintained by the <B>alias</B> builtin | |
1709 | Elements added to this array appear in the alias list; unsetting array | |
1710 | elements cause aliases to be removed from the alias list. | |
1711 | <DT><B>BASH_ARGC</B> | |
1712 | ||
1713 | <DD> | |
1714 | An array variable whose values are the number of parameters in each | |
1715 | frame of the current <B>bash</B> execution call stack. | |
1716 | The number of | |
1717 | parameters to the current subroutine (shell function or script executed | |
1718 | with <B>.</B> or <B>source</B>) is at the top of the stack. | |
1719 | When a subroutine is executed, the number of parameters passed is pushed onto | |
1720 | <B>BASH_ARGC</B>. | |
1721 | The shell sets <B>BASH_ARGC</B> only when in extended debugging mode | |
1722 | (see the description of the | |
1723 | <B>extdebug</B> | |
1724 | ||
1725 | option to the | |
1726 | <B>shopt</B> | |
1727 | ||
1728 | builtin below) | |
1729 | <DT><B>BASH_ARGV</B> | |
1730 | ||
1731 | <DD> | |
1732 | An array variable containing all of the parameters in the current <B>bash</B> | |
1733 | execution call stack. The final parameter of the last subroutine call | |
1734 | is at the top of the stack; the first parameter of the initial call is | |
1735 | at the bottom. When a subroutine is executed, the parameters supplied | |
1736 | are pushed onto <B>BASH_ARGV</B>. | |
1737 | The shell sets <B>BASH_ARGV</B> only when in extended debugging mode | |
1738 | (see the description of the | |
1739 | <B>extdebug</B> | |
1740 | ||
1741 | option to the | |
1742 | <B>shopt</B> | |
1743 | ||
1744 | builtin below) | |
1745 | <DT><B>BASH_CMDS</B> | |
1746 | ||
1747 | <DD> | |
1748 | An associative array variable whose members correspond to the internal | |
1749 | hash table of commands as maintained by the <B>hash</B> builtin. | |
1750 | Elements added to this array appear in the hash table; unsetting array | |
1751 | elements cause commands to be removed from the hash table. | |
1752 | <DT><B>BASH_COMMAND</B> | |
1753 | ||
1754 | <DD> | |
1755 | The command currently being executed or about to be executed, unless the | |
1756 | shell is executing a command as the result of a trap, | |
1757 | in which case it is the command executing at the time of the trap. | |
1758 | <DT><B>BASH_EXECUTION_STRING</B> | |
1759 | ||
1760 | <DD> | |
1761 | The command argument to the <B>-c</B> invocation option. | |
1762 | <DT><B>BASH_LINENO</B> | |
1763 | ||
1764 | <DD> | |
1765 | An array variable whose members are the line numbers in source files | |
1766 | corresponding to each member of <B>FUNCNAME</B>. | |
1767 | <B>${BASH_LINENO[</B><I>$i</I><B>]}</B> is the line number in the source | |
1768 | file where <B>${FUNCNAME[</B><I>$i</I><B>]}</B> was called | |
1769 | (or <B>${BASH_LINENO[</B><I>$i-1</I><B>]}</B> if referenced within another | |
1770 | shell function). | |
1771 | The corresponding source file name is <B>${BASH_SOURCE[</B><I>$i</I><B>]}. | |
1772 | Use LINENO</B> to obtain the current line number. | |
1773 | <DT><B>BASH_REMATCH</B> | |
1774 | ||
1775 | <DD> | |
1776 | An array variable whose members are assigned by the <B>=~</B> binary | |
1777 | operator to the <B>[[</B> conditional command. | |
1778 | The element with index 0 is the portion of the string | |
1779 | matching the entire regular expression. | |
1780 | The element with index <I>n</I> is the portion of the | |
1781 | string matching the <I>n</I>th parenthesized subexpression. | |
1782 | This variable is read-only. | |
1783 | <DT><B>BASH_SOURCE</B> | |
1784 | ||
1785 | <DD> | |
1786 | An array variable whose members are the source filenames corresponding | |
1787 | to the elements in the <B>FUNCNAME</B> array variable. | |
1788 | <DT><B>BASH_SUBSHELL</B> | |
1789 | ||
1790 | <DD> | |
1791 | Incremented by one each time a subshell or subshell environment is spawned. | |
1792 | The initial value is 0. | |
1793 | <DT><B>BASH_VERSINFO</B> | |
1794 | ||
1795 | <DD> | |
1796 | A readonly array variable whose members hold version information for | |
1797 | this instance of | |
1798 | <B>bash</B>. | |
1799 | ||
1800 | The values assigned to the array members are as follows: | |
1801 | <P> | |
1802 | <DL COMPACT><DT><DD> | |
1803 | ||
1804 | <DL COMPACT> | |
1805 | <DT><B>BASH_VERSINFO[</B>0] | |
1806 | ||
1807 | <DD> | |
1808 | The major version number (the <I>release</I>). | |
1809 | <DT><B>BASH_VERSINFO[</B>1] | |
1810 | ||
1811 | <DD> | |
1812 | The minor version number (the <I>version</I>). | |
1813 | <DT><B>BASH_VERSINFO[</B>2] | |
1814 | ||
1815 | <DD> | |
1816 | The patch level. | |
1817 | <DT><B>BASH_VERSINFO[</B>3] | |
1818 | ||
1819 | <DD> | |
1820 | The build version. | |
1821 | <DT><B>BASH_VERSINFO[</B>4] | |
1822 | ||
1823 | <DD> | |
1824 | The release status (e.g., <I>beta1</I>). | |
1825 | <DT><B>BASH_VERSINFO[</B>5] | |
1826 | ||
1827 | <DD> | |
1828 | The value of <B>MACHTYPE</B>. | |
1829 | ||
1830 | </DL></DL> | |
1831 | ||
1832 | <DT><B>BASH_VERSION</B> | |
1833 | ||
1834 | <DD> | |
1835 | Expands to a string describing the version of this instance of | |
1836 | <B>bash</B>. | |
1837 | ||
1838 | <DT><B>COMP_CWORD</B> | |
1839 | ||
1840 | <DD> | |
1841 | An index into <B>${COMP_WORDS}</B> of the word containing the current | |
1842 | cursor position. | |
1843 | This variable is available only in shell functions invoked by the | |
1844 | programmable completion facilities (see <B>Programmable Completion</B> | |
1845 | below). | |
1846 | <DT><B>COMP_KEY</B> | |
1847 | ||
1848 | <DD> | |
1849 | The key (or final key of a key sequence) used to invoke the current | |
1850 | completion function. | |
1851 | <DT><B>COMP_LINE</B> | |
1852 | ||
1853 | <DD> | |
1854 | The current command line. | |
1855 | This variable is available only in shell functions and external | |
1856 | commands invoked by the | |
1857 | programmable completion facilities (see <B>Programmable Completion</B> | |
1858 | below). | |
1859 | <DT><B>COMP_POINT</B> | |
1860 | ||
1861 | <DD> | |
1862 | The index of the current cursor position relative to the beginning of | |
1863 | the current command. | |
1864 | If the current cursor position is at the end of the current command, | |
1865 | the value of this variable is equal to <B>${#COMP_LINE}</B>. | |
1866 | This variable is available only in shell functions and external | |
1867 | commands invoked by the | |
1868 | programmable completion facilities (see <B>Programmable Completion</B> | |
1869 | below). | |
1870 | <DT><B>COMP_TYPE</B> | |
1871 | ||
1872 | <DD> | |
1873 | Set to an integer value corresponding to the type of completion attempted | |
1874 | that caused a completion function to be called: | |
1875 | <I>TAB</I>, for normal completion, | |
1876 | <I>?</I>, for listing completions after successive tabs, | |
1877 | <I>!</I>, for listing alternatives on partial word completion, | |
1878 | <I>@</I>, to list completions if the word is not unmodified, | |
1879 | or | |
1880 | <I>%</I>, for menu completion. | |
1881 | This variable is available only in shell functions and external | |
1882 | commands invoked by the | |
1883 | programmable completion facilities (see <B>Programmable Completion</B> | |
1884 | below). | |
1885 | <DT><B>COMP_WORDBREAKS</B> | |
1886 | ||
1887 | <DD> | |
1888 | The set of characters that the Readline library treats as word | |
1889 | separators when performing word completion. | |
1890 | If | |
1891 | <FONT SIZE=-1><B>COMP_WORDBREAKS</B> | |
1892 | ||
1893 | </FONT> | |
1894 | is unset, it loses its special properties, even if it is | |
1895 | subsequently reset. | |
1896 | <DT><B>COMP_WORDS</B> | |
1897 | ||
1898 | <DD> | |
1899 | An array variable (see <B>Arrays</B> below) consisting of the individual | |
1900 | words in the current command line. | |
1901 | The words are split on shell metacharacters as the shell parser would | |
1902 | separate them. | |
1903 | This variable is available only in shell functions invoked by the | |
1904 | programmable completion facilities (see <B>Programmable Completion</B> | |
1905 | below). | |
1906 | <DT><B>DIRSTACK</B> | |
1907 | ||
1908 | <DD> | |
1909 | An array variable (see | |
1910 | <B>Arrays</B> | |
1911 | ||
1912 | below) containing the current contents of the directory stack. | |
1913 | Directories appear in the stack in the order they are displayed by the | |
1914 | <B>dirs</B> | |
1915 | ||
1916 | builtin. | |
1917 | Assigning to members of this array variable may be used to modify | |
1918 | directories already in the stack, but the | |
1919 | <B>pushd</B> | |
1920 | ||
1921 | and | |
1922 | <B>popd</B> | |
1923 | ||
1924 | builtins must be used to add and remove directories. | |
1925 | Assignment to this variable will not change the current directory. | |
1926 | If | |
1927 | <FONT SIZE=-1><B>DIRSTACK</B> | |
1928 | ||
1929 | </FONT> | |
1930 | is unset, it loses its special properties, even if it is | |
1931 | subsequently reset. | |
1932 | <DT><B>EUID</B> | |
1933 | ||
1934 | <DD> | |
1935 | Expands to the effective user ID of the current user, initialized at | |
1936 | shell startup. This variable is readonly. | |
1937 | <DT><B>FUNCNAME</B> | |
1938 | ||
1939 | <DD> | |
1940 | An array variable containing the names of all shell functions | |
1941 | currently in the execution call stack. | |
1942 | The element with index 0 is the name of any currently-executing | |
1943 | shell function. | |
1944 | The bottom-most element is | |
1945 | <TT>"main"</TT>. | |
1946 | ||
1947 | This variable exists only when a shell function is executing. | |
1948 | Assignments to | |
1949 | <FONT SIZE=-1><B>FUNCNAME</B> | |
1950 | ||
1951 | </FONT> | |
1952 | have no effect and return an error status. | |
1953 | If | |
1954 | <FONT SIZE=-1><B>FUNCNAME</B> | |
1955 | ||
1956 | </FONT> | |
1957 | is unset, it loses its special properties, even if it is | |
1958 | subsequently reset. | |
1959 | <DT><B>GROUPS</B> | |
1960 | ||
1961 | <DD> | |
1962 | An array variable containing the list of groups of which the current | |
1963 | user is a member. | |
1964 | Assignments to | |
1965 | <FONT SIZE=-1><B>GROUPS</B> | |
1966 | ||
1967 | </FONT> | |
1968 | have no effect and return an error status. | |
1969 | If | |
1970 | <FONT SIZE=-1><B>GROUPS</B> | |
1971 | ||
1972 | </FONT> | |
1973 | is unset, it loses its special properties, even if it is | |
1974 | subsequently reset. | |
1975 | <DT><B>HISTCMD</B> | |
1976 | ||
1977 | <DD> | |
1978 | The history number, or index in the history list, of the current | |
1979 | command. | |
1980 | If | |
1981 | <FONT SIZE=-1><B>HISTCMD</B> | |
1982 | ||
1983 | </FONT> | |
1984 | is unset, it loses its special properties, even if it is | |
1985 | subsequently reset. | |
1986 | <DT><B>HOSTNAME</B> | |
1987 | ||
1988 | <DD> | |
1989 | Automatically set to the name of the current host. | |
1990 | <DT><B>HOSTTYPE</B> | |
1991 | ||
1992 | <DD> | |
1993 | Automatically set to a string that uniquely | |
1994 | describes the type of machine on which | |
1995 | <B>bash</B> | |
1996 | ||
1997 | is executing. | |
1998 | The default is system-dependent. | |
1999 | <DT><B>LINENO</B> | |
2000 | ||
2001 | <DD> | |
2002 | Each time this parameter is referenced, the shell substitutes | |
2003 | a decimal number representing the current sequential line number | |
2004 | (starting with 1) within a script or function. When not in a | |
2005 | script or function, the value substituted is not guaranteed to | |
2006 | be meaningful. | |
2007 | If | |
2008 | <FONT SIZE=-1><B>LINENO</B> | |
2009 | ||
2010 | </FONT> | |
2011 | is unset, it loses its special properties, even if it is | |
2012 | subsequently reset. | |
2013 | <DT><B>MACHTYPE</B> | |
2014 | ||
2015 | <DD> | |
2016 | Automatically set to a string that fully describes the system | |
2017 | type on which | |
2018 | <B>bash</B> | |
2019 | ||
2020 | is executing, in the standard GNU <I>cpu-company-system</I> format. | |
2021 | The default is system-dependent. | |
2022 | <DT><B>OLDPWD</B> | |
2023 | ||
2024 | <DD> | |
2025 | The previous working directory as set by the | |
2026 | <B>cd</B> | |
2027 | ||
2028 | command. | |
2029 | <DT><B>OPTARG</B> | |
2030 | ||
2031 | <DD> | |
2032 | The value of the last option argument processed by the | |
2033 | <B>getopts</B> | |
2034 | ||
2035 | builtin command (see | |
2036 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
2037 | ||
2038 | </FONT> | |
2039 | below). | |
2040 | <DT><B>OPTIND</B> | |
2041 | ||
2042 | <DD> | |
2043 | The index of the next argument to be processed by the | |
2044 | <B>getopts</B> | |
2045 | ||
2046 | builtin command (see | |
2047 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
2048 | ||
2049 | </FONT> | |
2050 | below). | |
2051 | <DT><B>OSTYPE</B> | |
2052 | ||
2053 | <DD> | |
2054 | Automatically set to a string that | |
2055 | describes the operating system on which | |
2056 | <B>bash</B> | |
2057 | ||
2058 | is executing. | |
2059 | The default is system-dependent. | |
2060 | <DT><B>PIPESTATUS</B> | |
2061 | ||
2062 | <DD> | |
2063 | An array variable (see | |
2064 | <B>Arrays</B> | |
2065 | ||
2066 | below) containing a list of exit status values from the processes | |
2067 | in the most-recently-executed foreground pipeline (which may | |
2068 | contain only a single command). | |
2069 | <DT><B>PPID</B> | |
2070 | ||
2071 | <DD> | |
2072 | The process ID of the shell's parent. This variable is readonly. | |
2073 | <DT><B>PWD</B> | |
2074 | ||
2075 | <DD> | |
2076 | The current working directory as set by the | |
2077 | <B>cd</B> | |
2078 | ||
2079 | command. | |
2080 | <DT><B>RANDOM</B> | |
2081 | ||
2082 | <DD> | |
2083 | Each time this parameter is referenced, a random integer between | |
2084 | 0 and 32767 is | |
2085 | generated. The sequence of random numbers may be initialized by assigning | |
2086 | a value to | |
2087 | <FONT SIZE=-1><B>RANDOM</B>. | |
2088 | ||
2089 | </FONT> | |
2090 | If | |
2091 | <FONT SIZE=-1><B>RANDOM</B> | |
2092 | ||
2093 | </FONT> | |
2094 | is unset, it loses its special properties, even if it is | |
2095 | subsequently reset. | |
2096 | <DT><B>REPLY</B> | |
2097 | ||
2098 | <DD> | |
2099 | Set to the line of input read by the | |
2100 | <B>read</B> | |
2101 | ||
2102 | builtin command when no arguments are supplied. | |
2103 | <DT><B>SECONDS</B> | |
2104 | ||
2105 | <DD> | |
2106 | Each time this parameter is | |
2107 | referenced, the number of seconds since shell invocation is returned. If a | |
2108 | value is assigned to | |
2109 | <FONT SIZE=-1><B>SECONDS</B>, | |
2110 | ||
2111 | </FONT> | |
2112 | the value returned upon subsequent | |
2113 | references is | |
2114 | the number of seconds since the assignment plus the value assigned. | |
2115 | If | |
2116 | <FONT SIZE=-1><B>SECONDS</B> | |
2117 | ||
2118 | </FONT> | |
2119 | is unset, it loses its special properties, even if it is | |
2120 | subsequently reset. | |
2121 | <DT><B>SHELLOPTS</B> | |
2122 | ||
2123 | <DD> | |
2124 | A colon-separated list of enabled shell options. Each word in | |
2125 | the list is a valid argument for the | |
2126 | <B>-o</B> | |
2127 | ||
2128 | option to the | |
2129 | <B>set</B> | |
2130 | ||
2131 | builtin command (see | |
2132 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
2133 | ||
2134 | </FONT> | |
2135 | below). The options appearing in | |
2136 | <FONT SIZE=-1><B>SHELLOPTS</B> | |
2137 | ||
2138 | </FONT> | |
2139 | are those reported as | |
2140 | <I>on</I> | |
2141 | ||
2142 | by <B>set -o</B>. | |
2143 | If this variable is in the environment when | |
2144 | <B>bash</B> | |
2145 | ||
2146 | starts up, each shell option in the list will be enabled before | |
2147 | reading any startup files. | |
2148 | This variable is read-only. | |
2149 | <DT><B>SHLVL</B> | |
2150 | ||
2151 | <DD> | |
2152 | Incremented by one each time an instance of | |
2153 | <B>bash</B> | |
2154 | ||
2155 | is started. | |
2156 | <DT><B>UID</B> | |
2157 | ||
2158 | <DD> | |
2159 | Expands to the user ID of the current user, initialized at shell startup. | |
2160 | This variable is readonly. | |
2161 | ||
2162 | </DL> | |
2163 | <P> | |
2164 | ||
2165 | The following variables are used by the shell. In some cases, | |
2166 | <B>bash</B> | |
2167 | ||
2168 | assigns a default value to a variable; these cases are noted | |
2169 | below. | |
2170 | <P> | |
2171 | ||
2172 | ||
2173 | <DL COMPACT> | |
2174 | <DT><B>BASH_ENV</B> | |
2175 | ||
2176 | <DD> | |
2177 | If this parameter is set when <B>bash</B> is executing a shell script, | |
2178 | its value is interpreted as a filename containing commands to | |
2179 | initialize the shell, as in | |
2180 | <A HREF="file:~/.bashrc"><I>~/.bashrc</I></A>. | |
2181 | ||
2182 | The value of | |
2183 | <FONT SIZE=-1><B>BASH_ENV</B> | |
2184 | ||
2185 | </FONT> | |
2186 | is subjected to parameter expansion, command substitution, and arithmetic | |
2187 | expansion before being interpreted as a file name. | |
2188 | <FONT SIZE=-1><B>PATH</B> | |
2189 | ||
2190 | </FONT> | |
2191 | is not used to search for the resultant file name. | |
2192 | <DT><B>CDPATH</B> | |
2193 | ||
2194 | <DD> | |
2195 | The search path for the | |
2196 | <B>cd</B> | |
2197 | ||
2198 | command. | |
2199 | This is a colon-separated list of directories in which the shell looks | |
2200 | for destination directories specified by the | |
2201 | <B>cd</B> | |
2202 | ||
2203 | command. | |
2204 | A sample value is | |
2205 | <TT>".:~:/usr"</TT>. | |
2206 | ||
2207 | <DT><B>COLUMNS</B> | |
2208 | ||
2209 | <DD> | |
2210 | Used by the <B>select</B> builtin command to determine the terminal width | |
2211 | when printing selection lists. Automatically set upon receipt of a SIGWINCH. | |
2212 | <DT><B>COMPREPLY</B> | |
2213 | ||
2214 | <DD> | |
2215 | An array variable from which <B>bash</B> reads the possible completions | |
2216 | generated by a shell function invoked by the programmable completion | |
2217 | facility (see <B>Programmable Completion</B> below). | |
2218 | <DT><B>EMACS</B> | |
2219 | ||
2220 | <DD> | |
2221 | If <B>bash</B> finds this variable in the environment when the shell starts | |
2222 | with value | |
2223 | <TT>t</TT>, | |
2224 | ||
2225 | it assumes that the shell is running in an emacs shell buffer and disables | |
2226 | line editing. | |
2227 | <DT><B>FCEDIT</B> | |
2228 | ||
2229 | <DD> | |
2230 | The default editor for the | |
2231 | <B>fc</B> | |
2232 | ||
2233 | builtin command. | |
2234 | <DT><B>FIGNORE</B> | |
2235 | ||
2236 | <DD> | |
2237 | A colon-separated list of suffixes to ignore when performing | |
2238 | filename completion (see | |
2239 | <FONT SIZE=-1><B>READLINE</B> | |
2240 | ||
2241 | </FONT> | |
2242 | below). | |
2243 | A filename whose suffix matches one of the entries in | |
2244 | <FONT SIZE=-1><B>FIGNORE</B> | |
2245 | ||
2246 | </FONT> | |
2247 | is excluded from the list of matched filenames. | |
2248 | A sample value is | |
2249 | <TT>".o:~"</TT>. | |
2250 | ||
2251 | <DT><B>GLOBIGNORE</B> | |
2252 | ||
2253 | <DD> | |
2254 | A colon-separated list of patterns defining the set of filenames to | |
2255 | be ignored by pathname expansion. | |
2256 | If a filename matched by a pathname expansion pattern also matches one | |
2257 | of the patterns in | |
2258 | <FONT SIZE=-1><B>GLOBIGNORE</B>, | |
2259 | ||
2260 | </FONT> | |
2261 | it is removed from the list of matches. | |
2262 | <DT><B>HISTCONTROL</B> | |
2263 | ||
2264 | <DD> | |
2265 | A colon-separated list of values controlling how commands are saved on | |
2266 | the history list. | |
2267 | If the list of values includes | |
2268 | <I>ignorespace</I>, | |
2269 | ||
2270 | lines which begin with a | |
2271 | <B>space</B> | |
2272 | ||
2273 | character are not saved in the history list. | |
2274 | A value of | |
2275 | <I>ignoredups</I> | |
2276 | ||
2277 | causes lines matching the previous history entry to not be saved. | |
2278 | A value of | |
2279 | <I>ignoreboth</I> | |
2280 | ||
2281 | is shorthand for <I>ignorespace</I> and <I>ignoredups</I>. | |
2282 | A value of | |
2283 | <I>erasedups</I> | |
2284 | ||
2285 | causes all previous lines matching the current line to be removed from | |
2286 | the history list before that line is saved. | |
2287 | Any value not in the above list is ignored. | |
2288 | If <B>HISTCONTROL</B> is unset, or does not include a valid value, | |
2289 | all lines read by the shell parser are saved on the history list, | |
2290 | subject to the value of | |
2291 | <B>HISTIGNORE</B>. | |
2292 | ||
2293 | The second and subsequent lines of a multi-line compound command are | |
2294 | not tested, and are added to the history regardless of the value of | |
2295 | <B>HISTCONTROL</B>. | |
2296 | ||
2297 | <DT><B>HISTFILE</B> | |
2298 | ||
2299 | <DD> | |
2300 | The name of the file in which command history is saved (see | |
2301 | <FONT SIZE=-1><B>HISTORY</B> | |
2302 | ||
2303 | </FONT> | |
2304 | below). The default value is <A HREF="file:~/.bash_history"><I>~/.bash_history</I></A>. If unset, the | |
2305 | command history is not saved when an interactive shell exits. | |
2306 | <DT><B>HISTFILESIZE</B> | |
2307 | ||
2308 | <DD> | |
2309 | The maximum number of lines contained in the history file. When this | |
2310 | variable is assigned a value, the history file is truncated, if | |
2311 | necessary, by removing the oldest entries, | |
2312 | to contain no more than that number of lines. The default | |
2313 | value is 500. The history file is also truncated to this size after | |
2314 | writing it when an interactive shell exits. | |
2315 | <DT><B>HISTIGNORE</B> | |
2316 | ||
2317 | <DD> | |
2318 | A colon-separated list of patterns used to decide which command lines | |
2319 | should be saved on the history list. Each pattern is anchored at the | |
2320 | beginning of the line and must match the complete line (no implicit | |
2321 | `<B>*</B>' is appended). Each pattern is tested against the line | |
2322 | after the checks specified by | |
2323 | <B>HISTCONTROL</B> | |
2324 | ||
2325 | are applied. | |
2326 | In addition to the normal shell pattern matching characters, `<B>&</B>' | |
2327 | matches the previous history line. `<B>&</B>' may be escaped using a | |
2328 | backslash; the backslash is removed before attempting a match. | |
2329 | The second and subsequent lines of a multi-line compound command are | |
2330 | not tested, and are added to the history regardless of the value of | |
2331 | <B>HISTIGNORE</B>. | |
2332 | ||
2333 | <DT><B>HISTSIZE</B> | |
2334 | ||
2335 | <DD> | |
2336 | The number of commands to remember in the command history (see | |
2337 | <FONT SIZE=-1><B>HISTORY</B> | |
2338 | ||
2339 | </FONT> | |
2340 | below). The default value is 500. | |
2341 | <DT><B>HISTTIMEFORMAT</B> | |
2342 | ||
2343 | <DD> | |
2344 | If this variable is set and not null, its value is used as a format string | |
2345 | for <I>strftime</I>(3) to print the time stamp associated with each history | |
2346 | entry displayed by the <B>history</B> builtin. | |
2347 | If this variable is set, time stamps are written to the history file so | |
2348 | they may be preserved across shell sessions. | |
2349 | This uses the history comment character to distinguish timestamps from | |
2350 | other history lines. | |
2351 | <DT><B>HOME</B> | |
2352 | ||
2353 | <DD> | |
2354 | The home directory of the current user; the default argument for the | |
2355 | <B>cd</B> builtin command. | |
2356 | The value of this variable is also used when performing tilde expansion. | |
2357 | <DT><B>HOSTFILE</B> | |
2358 | ||
2359 | <DD> | |
2360 | Contains the name of a file in the same format as | |
2361 | ||
2362 | <I>/etc/hosts</I> | |
2363 | ||
2364 | that should be read when the shell needs to complete a | |
2365 | hostname. | |
2366 | The list of possible hostname completions may be changed while the | |
2367 | shell is running; | |
2368 | the next time hostname completion is attempted after the | |
2369 | value is changed, | |
2370 | <B>bash</B> | |
2371 | ||
2372 | adds the contents of the new file to the existing list. | |
2373 | If | |
2374 | <FONT SIZE=-1><B>HOSTFILE</B> | |
2375 | ||
2376 | </FONT> | |
2377 | is set, but has no value, <B>bash</B> attempts to read | |
2378 | ||
2379 | <I>/etc/hosts</I> | |
2380 | ||
2381 | to obtain the list of possible hostname completions. | |
2382 | When | |
2383 | <FONT SIZE=-1><B>HOSTFILE</B> | |
2384 | ||
2385 | </FONT> | |
2386 | is unset, the hostname list is cleared. | |
2387 | <DT><B>IFS</B> | |
2388 | ||
2389 | <DD> | |
2390 | The | |
2391 | <I>Internal Field Separator</I> | |
2392 | ||
2393 | that is used | |
2394 | for word splitting after expansion and to | |
2395 | split lines into words with the | |
2396 | <B>read</B> | |
2397 | ||
2398 | builtin command. The default value is | |
2399 | ``<space><tab><newline>''. | |
2400 | <DT><B>IGNOREEOF</B> | |
2401 | ||
2402 | <DD> | |
2403 | Controls the | |
2404 | action of an interactive shell on receipt of an | |
2405 | <FONT SIZE=-1><B>EOF</B> | |
2406 | ||
2407 | </FONT> | |
2408 | character as the sole input. If set, the value is the number of | |
2409 | consecutive | |
2410 | <FONT SIZE=-1><B>EOF</B> | |
2411 | ||
2412 | </FONT> | |
2413 | characters which must be | |
2414 | typed as the first characters on an input line before | |
2415 | <B>bash</B> | |
2416 | ||
2417 | exits. If the variable exists but does not have a numeric value, or | |
2418 | has no value, the default value is 10. If it does not exist, | |
2419 | <FONT SIZE=-1><B>EOF</B> | |
2420 | ||
2421 | </FONT> | |
2422 | signifies the end of input to the shell. | |
2423 | <DT><B>INPUTRC</B> | |
2424 | ||
2425 | <DD> | |
2426 | The filename for the | |
2427 | <B>readline</B> | |
2428 | ||
2429 | startup file, overriding the default of | |
2430 | ||
2431 | <A HREF="file:~/.inputrc"><I>~/.inputrc</I></A> | |
2432 | ||
2433 | (see | |
2434 | <FONT SIZE=-1><B>READLINE</B> | |
2435 | ||
2436 | </FONT> | |
2437 | below). | |
2438 | <DT><B>LANG</B> | |
2439 | ||
2440 | <DD> | |
2441 | Used to determine the locale category for any category not specifically | |
2442 | selected with a variable starting with <B>LC_</B>. | |
2443 | <DT><B>LC_ALL</B> | |
2444 | ||
2445 | <DD> | |
2446 | This variable overrides the value of <B>LANG</B> and any other | |
2447 | <B>LC_</B> variable specifying a locale category. | |
2448 | <DT><B>LC_COLLATE</B> | |
2449 | ||
2450 | <DD> | |
2451 | This variable determines the collation order used when sorting the | |
2452 | results of pathname expansion, and determines the behavior of range | |
2453 | expressions, equivalence classes, and collating sequences within | |
2454 | pathname expansion and pattern matching. | |
2455 | <DT><B>LC_CTYPE</B> | |
2456 | ||
2457 | <DD> | |
2458 | This variable determines the interpretation of characters and the | |
2459 | behavior of character classes within pathname expansion and pattern | |
2460 | matching. | |
2461 | <DT><B>LC_MESSAGES</B> | |
2462 | ||
2463 | <DD> | |
2464 | This variable determines the locale used to translate double-quoted | |
2465 | strings preceded by a <B>$</B>. | |
2466 | <DT><B>LC_NUMERIC</B> | |
2467 | ||
2468 | <DD> | |
2469 | This variable determines the locale category used for number formatting. | |
2470 | <DT><B>LINES</B> | |
2471 | ||
2472 | <DD> | |
2473 | Used by the <B>select</B> builtin command to determine the column length | |
2474 | for printing selection lists. Automatically set upon receipt of a SIGWINCH. | |
2475 | <DT><B>MAIL</B> | |
2476 | ||
2477 | <DD> | |
2478 | If this parameter is set to a file name and the | |
2479 | <FONT SIZE=-1><B>MAILPATH</B> | |
2480 | ||
2481 | </FONT> | |
2482 | variable is not set, | |
2483 | <B>bash</B> | |
2484 | ||
2485 | informs the user of the arrival of mail in the specified file. | |
2486 | <DT><B>MAILCHECK</B> | |
2487 | ||
2488 | <DD> | |
2489 | Specifies how | |
2490 | often (in seconds) | |
2491 | <B>bash</B> | |
2492 | ||
2493 | checks for mail. The default is 60 seconds. When it is time to check | |
2494 | for mail, the shell does so before displaying the primary prompt. | |
2495 | If this variable is unset, or set to a value that is not a number | |
2496 | greater than or equal to zero, the shell disables mail checking. | |
2497 | <DT><B>MAILPATH</B> | |
2498 | ||
2499 | <DD> | |
2500 | A colon-separated list of file names to be checked for mail. | |
2501 | The message to be printed when mail arrives in a particular file | |
2502 | may be specified by separating the file name from the message with a `?'. | |
2503 | When used in the text of the message, <B>$_</B> expands to the name of | |
2504 | the current mailfile. | |
2505 | Example: | |
2506 | <DL COMPACT><DT><DD> | |
2507 | <P> | |
2508 | ||
2509 | <B>MAILPATH</B>=aq/var/mail/bfox?"You have mail":~/shell-mail?"$_ has mail!"aq | |
2510 | <P> | |
2511 | ||
2512 | <B>Bash</B> | |
2513 | ||
2514 | supplies a default value for this variable, but the location of the user | |
2515 | mail files that it uses is system dependent (e.g., /var/mail/<B>$USER</B>). | |
2516 | </DL> | |
2517 | ||
2518 | <DT><B>OPTERR</B> | |
2519 | ||
2520 | <DD> | |
2521 | If set to the value 1, | |
2522 | <B>bash</B> | |
2523 | ||
2524 | displays error messages generated by the | |
2525 | <B>getopts</B> | |
2526 | ||
2527 | builtin command (see | |
2528 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
2529 | ||
2530 | </FONT> | |
2531 | below). | |
2532 | <FONT SIZE=-1><B>OPTERR</B> | |
2533 | ||
2534 | </FONT> | |
2535 | is initialized to 1 each time the shell is invoked or a shell | |
2536 | script is executed. | |
2537 | <DT><B>PATH</B> | |
2538 | ||
2539 | <DD> | |
2540 | The search path for commands. It | |
2541 | is a colon-separated list of directories in which | |
2542 | the shell looks for commands (see | |
2543 | <FONT SIZE=-1><B>COMMAND EXECUTION</B> | |
2544 | ||
2545 | </FONT> | |
2546 | below). | |
2547 | A zero-length (null) directory name in the value of <B>PATH</B> indicates the | |
2548 | current directory. | |
2549 | A null directory name may appear as two adjacent colons, or as an initial | |
2550 | or trailing colon. | |
2551 | The default path is system-dependent, | |
2552 | and is set by the administrator who installs | |
2553 | <B>bash</B>. | |
2554 | ||
2555 | A common value is | |
2556 | <TT>/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin</TT>. | |
2557 | ||
2558 | <DT><B>POSIXLY_CORRECT</B> | |
2559 | ||
2560 | <DD> | |
2561 | If this variable is in the environment when <B>bash</B> starts, the shell | |
2562 | enters <I>posix mode</I> before reading the startup files, as if the | |
2563 | <B>--posix</B> | |
2564 | ||
2565 | invocation option had been supplied. If it is set while the shell is | |
2566 | running, <B>bash</B> enables <I>posix mode</I>, as if the command | |
2567 | <TT>set -o posix</TT> | |
2568 | ||
2569 | had been executed. | |
2570 | <DT><B>PROMPT_COMMAND</B> | |
2571 | ||
2572 | <DD> | |
2573 | If set, the value is executed as a command prior to issuing each primary | |
2574 | prompt. | |
2575 | <DT><B>PROMPT_DIRTRIM</B> | |
2576 | ||
2577 | <DD> | |
2578 | If set to a number greater than zero, the value is used as the number of | |
2579 | trailing directory components to retain when expanding the <B>\w and | |
2580 | \W</B> prompt string escapes (see | |
2581 | <FONT SIZE=-1><B>PROMPTING</B> | |
2582 | ||
2583 | </FONT> | |
2584 | below). Characters removed are replaced with an ellipsis. | |
2585 | <DT><B>PS1</B> | |
2586 | ||
2587 | <DD> | |
2588 | The value of this parameter is expanded (see | |
2589 | <FONT SIZE=-1><B>PROMPTING</B> | |
2590 | ||
2591 | </FONT> | |
2592 | below) and used as the primary prompt string. The default value is | |
2593 | ``<B>\s-\v\$ </B>''. | |
2594 | <DT><B>PS2</B> | |
2595 | ||
2596 | <DD> | |
2597 | The value of this parameter is expanded as with | |
2598 | <B>PS1</B> | |
2599 | ||
2600 | and used as the secondary prompt string. The default is | |
2601 | ``<B>> </B>''. | |
2602 | <DT><B>PS3</B> | |
2603 | ||
2604 | <DD> | |
2605 | The value of this parameter is used as the prompt for the | |
2606 | <B>select</B> | |
2607 | ||
2608 | command (see | |
2609 | <FONT SIZE=-1><B>SHELL GRAMMAR</B> | |
2610 | ||
2611 | </FONT> | |
2612 | above). | |
2613 | <DT><B>PS4</B> | |
2614 | ||
2615 | <DD> | |
2616 | The value of this parameter is expanded as with | |
2617 | <B>PS1</B> | |
2618 | ||
2619 | and the value is printed before each command | |
2620 | <B>bash</B> | |
2621 | ||
2622 | displays during an execution trace. The first character of | |
2623 | <FONT SIZE=-1><B>PS4</B> | |
2624 | ||
2625 | </FONT> | |
2626 | is replicated multiple times, as necessary, to indicate multiple | |
2627 | levels of indirection. The default is ``<B>+ </B>''. | |
2628 | <DT><B>SHELL</B> | |
2629 | ||
2630 | <DD> | |
2631 | The full pathname to the shell is kept in this environment variable. | |
2632 | If it is not set when the shell starts, | |
2633 | <B>bash</B> | |
2634 | ||
2635 | assigns to it the full pathname of the current user's login shell. | |
2636 | <DT><B>TIMEFORMAT</B> | |
2637 | ||
2638 | <DD> | |
2639 | The value of this parameter is used as a format string specifying | |
2640 | how the timing information for pipelines prefixed with the | |
2641 | <B>time</B> | |
2642 | ||
2643 | reserved word should be displayed. | |
2644 | The <B>%</B> character introduces an escape sequence that is | |
2645 | expanded to a time value or other information. | |
2646 | The escape sequences and their meanings are as follows; the | |
2647 | braces denote optional portions. | |
2648 | <P> | |
2649 | <DL COMPACT><DT><DD> | |
2650 | ||
2651 | <DL COMPACT> | |
2652 | <DT><B>%%</B> | |
2653 | ||
2654 | <DD> | |
2655 | A literal <B>%</B>. | |
2656 | <DT><B>%[</B><I>p</I>][l]R | |
2657 | ||
2658 | <DD> | |
2659 | The elapsed time in seconds. | |
2660 | <DT><B>%[</B><I>p</I>][l]U | |
2661 | ||
2662 | <DD> | |
2663 | The number of CPU seconds spent in user mode. | |
2664 | <DT><B>%[</B><I>p</I>][l]S | |
2665 | ||
2666 | <DD> | |
2667 | The number of CPU seconds spent in system mode. | |
2668 | <DT><B>%P</B> | |
2669 | ||
2670 | <DD> | |
2671 | The CPU percentage, computed as (%U + %S) / %R. | |
2672 | ||
2673 | </DL></DL> | |
2674 | ||
2675 | <DT><DD> | |
2676 | The optional <I>p</I> is a digit specifying the <I>precision</I>, | |
2677 | the number of fractional digits after a decimal point. | |
2678 | A value of 0 causes no decimal point or fraction to be output. | |
2679 | At most three places after the decimal point may be specified; | |
2680 | values of <I>p</I> greater than 3 are changed to 3. | |
2681 | If <I>p</I> is not specified, the value 3 is used. | |
2682 | <DT><DD> | |
2683 | The optional <B>l</B> specifies a longer format, including | |
2684 | minutes, of the form <I>MM</I>m<I>SS</I>.<I>FF</I>s. | |
2685 | The value of <I>p</I> determines whether or not the fraction is | |
2686 | included. | |
2687 | <DT><DD> | |
2688 | If this variable is not set, <B>bash</B> acts as if it had the | |
2689 | value <B>$aq\nreal\t%3lR\nuser\t%3lU\nsys %3lSaq</B>. | |
2690 | If the value is null, no timing information is displayed. | |
2691 | A trailing newline is added when the format string is displayed. | |
2692 | <DT><B>TMOUT</B> | |
2693 | ||
2694 | <DD> | |
2695 | If set to a value greater than zero, <B>TMOUT</B> is treated as the | |
2696 | default timeout for the <B>read</B> builtin. | |
2697 | The <B>select</B> command terminates if input does not arrive | |
2698 | after <B>TMOUT</B> seconds when input is coming from a terminal. | |
2699 | In an interactive shell, the value is interpreted as the | |
2700 | number of seconds to wait for input after issuing the primary prompt. | |
2701 | <B>Bash</B> | |
2702 | ||
2703 | terminates after waiting for that number of seconds if input does | |
2704 | not arrive. | |
2705 | <DT><B>TMPDIR</B> | |
2706 | ||
2707 | <DD> | |
2708 | If set, <B>Bash</B> uses its value as the name of a directory in which | |
2709 | <B>Bash</B> creates temporary files for the shell's use. | |
2710 | <DT><B>auto_resume</B> | |
2711 | ||
2712 | <DD> | |
2713 | This variable controls how the shell interacts with the user and | |
2714 | job control. If this variable is set, single word simple | |
2715 | commands without redirections are treated as candidates for resumption | |
2716 | of an existing stopped job. There is no ambiguity allowed; if there is | |
2717 | more than one job beginning with the string typed, the job most recently | |
2718 | accessed is selected. The | |
2719 | <I>name</I> | |
2720 | ||
2721 | of a stopped job, in this context, is the command line used to | |
2722 | start it. | |
2723 | If set to the value | |
2724 | <I>exact</I>, | |
2725 | ||
2726 | the string supplied must match the name of a stopped job exactly; | |
2727 | if set to | |
2728 | <I>substring</I>, | |
2729 | ||
2730 | the string supplied needs to match a substring of the name of a | |
2731 | stopped job. The | |
2732 | <I>substring</I> | |
2733 | ||
2734 | value provides functionality analogous to the | |
2735 | <B>%?</B> | |
2736 | ||
2737 | job identifier (see | |
2738 | <FONT SIZE=-1><B>JOB CONTROL</B> | |
2739 | ||
2740 | </FONT> | |
2741 | below). If set to any other value, the supplied string must | |
2742 | be a prefix of a stopped job's name; this provides functionality | |
2743 | analogous to the <B>%</B><I>string</I> job identifier. | |
2744 | <DT><B>histchars</B> | |
2745 | ||
2746 | <DD> | |
2747 | The two or three characters which control history expansion | |
2748 | and tokenization (see | |
2749 | <FONT SIZE=-1><B>HISTORY EXPANSION</B> | |
2750 | ||
2751 | </FONT> | |
2752 | below). The first character is the <I>history expansion</I> character, | |
2753 | the character which signals the start of a history | |
2754 | expansion, normally `<B>!</B>'. | |
2755 | The second character is the <I>quick substitution</I> | |
2756 | character, which is used as shorthand for re-running the previous | |
2757 | command entered, substituting one string for another in the command. | |
2758 | The default is `<B>^</B>'. | |
2759 | The optional third character is the character | |
2760 | which indicates that the remainder of the line is a comment when found | |
2761 | as the first character of a word, normally `<B>#</B>'. The history | |
2762 | comment character causes history substitution to be skipped for the | |
2763 | remaining words on the line. It does not necessarily cause the shell | |
2764 | parser to treat the rest of the line as a comment. | |
2765 | ||
2766 | </DL> | |
2767 | <A NAME="lbAX"> </A> | |
2768 | <H4>Arrays</H4> | |
2769 | ||
2770 | <B>Bash</B> | |
2771 | ||
2772 | provides one-dimensional indexed and associative array variables. | |
2773 | Any variable may be used as an indexed array; the | |
2774 | <B>declare</B> | |
2775 | ||
2776 | builtin will explicitly declare an array. | |
2777 | There is no maximum | |
2778 | limit on the size of an array, nor any requirement that members | |
2779 | be indexed or assigned contiguously. | |
2780 | Indexed arrays are referenced using integers (including arithmetic | |
2781 | expressions) and are zero-based; associative arrays are referenced | |
2782 | using arbitrary strings. | |
2783 | <P> | |
2784 | ||
2785 | An indexed array is created automatically if any variable is assigned to | |
2786 | using the syntax <I>name</I>[<I>subscript</I>]=<I>value</I>. The | |
2787 | <I>subscript</I> | |
2788 | ||
2789 | is treated as an arithmetic expression that must evaluate to a number | |
2790 | greater than or equal to zero. To explicitly declare an indexed array, | |
2791 | use | |
2792 | <B>declare -a </B><I>name</I> | |
2793 | ||
2794 | (see | |
2795 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
2796 | ||
2797 | </FONT> | |
2798 | below). | |
2799 | <B>declare -a </B><I>name</I>[<I>subscript</I>] | |
2800 | ||
2801 | is also accepted; the <I>subscript</I> is ignored. | |
2802 | <P> | |
2803 | ||
2804 | Associative arrays are created using | |
2805 | <B>declare -A </B><I>name</I>. | |
2806 | ||
2807 | <P> | |
2808 | ||
2809 | Attributes may be | |
2810 | specified for an array variable using the | |
2811 | <B>declare</B> | |
2812 | ||
2813 | and | |
2814 | <B>readonly</B> | |
2815 | ||
2816 | builtins. Each attribute applies to all members of an array. | |
2817 | <P> | |
2818 | ||
2819 | Arrays are assigned to using compound assignments of the form | |
2820 | <I>name</I>=<B>(</B>value<I>1</I> ... value<I>n</I><B>)</B>, where each | |
2821 | <I>value</I> is of the form [<I>subscript</I>]=<I>string</I>. | |
2822 | Indexed array assignments do not require the bracket and subscript. | |
2823 | When assigning to indexed arrays, if the optional brackets and subscript | |
2824 | are supplied, that index is assigned to; | |
2825 | otherwise the index of the element assigned is the last index assigned | |
2826 | to by the statement plus one. Indexing starts at zero. | |
2827 | <P> | |
2828 | ||
2829 | When assigning to an associative array, the subscript is required. | |
2830 | <P> | |
2831 | ||
2832 | This syntax is also accepted by the | |
2833 | <B>declare</B> | |
2834 | ||
2835 | builtin. Individual array elements may be assigned to using the | |
2836 | <I>name</I>[<I>subscript</I>]=<I>value</I> syntax introduced above. | |
2837 | <P> | |
2838 | ||
2839 | Any element of an array may be referenced using | |
2840 | ${<I>name</I>[<I>subscript</I>]}. The braces are required to avoid | |
2841 | conflicts with pathname expansion. If | |
2842 | <I>subscript</I> is <B>@</B> or <B>*</B>, the word expands to | |
2843 | all members of <I>name</I>. These subscripts differ only when the | |
2844 | word appears within double quotes. If the word is double-quoted, | |
2845 | ${<I>name</I>[*]} expands to a single | |
2846 | word with the value of each array member separated by the first | |
2847 | character of the | |
2848 | <FONT SIZE=-1><B>IFS</B> | |
2849 | ||
2850 | </FONT> | |
2851 | special variable, and ${<I>name</I>[@]} expands each element of | |
2852 | <I>name</I> to a separate word. When there are no array members, | |
2853 | ${<I>name</I>[@]} expands to nothing. | |
2854 | If the double-quoted expansion occurs within a word, the expansion of | |
2855 | the first parameter is joined with the beginning part of the original | |
2856 | word, and the expansion of the last parameter is joined with the last | |
2857 | part of the original word. | |
2858 | This is analogous to the expansion | |
2859 | of the special parameters <B>*</B> and <B>@</B> (see | |
2860 | <B>Special Parameters</B> | |
2861 | ||
2862 | above). ${#<I>name</I>[<I>subscript</I>]} expands to the length of | |
2863 | ${<I>name</I>[<I>subscript</I>]}. If <I>subscript</I> is <B>*</B> or | |
2864 | <B>@</B>, the expansion is the number of elements in the array. | |
2865 | Referencing an array variable without a subscript is equivalent to | |
2866 | referencing the array with a subscript of 0. | |
2867 | <P> | |
2868 | ||
2869 | The | |
2870 | <B>unset</B> | |
2871 | ||
2872 | builtin is used to destroy arrays. <B>unset</B> <I>name</I>[<I>subscript</I>] | |
2873 | destroys the array element at index <I>subscript</I>. | |
2874 | Care must be taken to avoid unwanted side effects caused by filename | |
2875 | generation. | |
2876 | <B>unset</B> <I>name</I>, where <I>name</I> is an array, or | |
2877 | <B>unset</B> <I>name</I>[<I>subscript</I>], where | |
2878 | <I>subscript</I> is <B>*</B> or <B>@</B>, removes the entire array. | |
2879 | <P> | |
2880 | ||
2881 | The | |
2882 | <B>declare</B>, | |
2883 | ||
2884 | <B>local</B>, | |
2885 | ||
2886 | and | |
2887 | <B>readonly</B> | |
2888 | ||
2889 | builtins each accept a | |
2890 | <B>-a</B> | |
2891 | ||
2892 | option to specify an indexed array and a | |
2893 | <B>-A</B> | |
2894 | ||
2895 | option to specify an associative array. | |
2896 | The | |
2897 | <B>read</B> | |
2898 | ||
2899 | builtin accepts a | |
2900 | <B>-a</B> | |
2901 | ||
2902 | option to assign a list of words read from the standard input | |
2903 | to an array. The | |
2904 | <B>set</B> | |
2905 | ||
2906 | and | |
2907 | <B>declare</B> | |
2908 | ||
2909 | builtins display array values in a way that allows them to be | |
2910 | reused as assignments. | |
2911 | <A NAME="lbAY"> </A> | |
2912 | <H3>EXPANSION</H3> | |
2913 | ||
2914 | Expansion is performed on the command line after it has been split into | |
2915 | words. There are seven kinds of expansion performed: | |
2916 | <I>brace expansion</I>, | |
2917 | ||
2918 | <I>tilde expansion</I>, | |
2919 | ||
2920 | <I>parameter and variable expansion</I>, | |
2921 | ||
2922 | <I>command substitution</I>, | |
2923 | ||
2924 | <I>arithmetic expansion</I>, | |
2925 | ||
2926 | <I>word splitting</I>, | |
2927 | ||
2928 | and | |
2929 | <I>pathname expansion</I>. | |
2930 | ||
2931 | <P> | |
2932 | ||
2933 | The order of expansions is: brace expansion, tilde expansion, | |
2934 | parameter, variable and arithmetic expansion and | |
2935 | command substitution | |
2936 | (done in a left-to-right fashion), word splitting, and pathname | |
2937 | expansion. | |
2938 | <P> | |
2939 | ||
2940 | On systems that can support it, there is an additional expansion | |
2941 | available: <I>process substitution</I>. | |
2942 | <P> | |
2943 | ||
2944 | Only brace expansion, word splitting, and pathname expansion | |
2945 | can change the number of words of the expansion; other expansions | |
2946 | expand a single word to a single word. | |
2947 | The only exceptions to this are the expansions of | |
2948 | "<B>$@</B>" and "<B>${</B><I>name</I><B>[@]}</B>" | |
2949 | as explained above (see | |
2950 | <FONT SIZE=-1><B>PARAMETERS</B>). | |
2951 | ||
2952 | </FONT> | |
2953 | <A NAME="lbAZ"> </A> | |
2954 | <H4>Brace Expansion</H4> | |
2955 | ||
2956 | <P> | |
2957 | ||
2958 | <I>Brace expansion</I> | |
2959 | ||
2960 | is a mechanism by which arbitrary strings | |
2961 | may be generated. This mechanism is similar to | |
2962 | <I>pathname expansion</I>, but the filenames generated | |
2963 | need not exist. Patterns to be brace expanded take | |
2964 | the form of an optional | |
2965 | <I>preamble</I>, | |
2966 | ||
2967 | followed by either a series of comma-separated strings or | |
2968 | a sequence expression between a pair of braces, followed by | |
2969 | an optional | |
2970 | <I>postscript</I>. | |
2971 | ||
2972 | The preamble is prefixed to each string contained | |
2973 | within the braces, and the postscript is then appended | |
2974 | to each resulting string, expanding left to right. | |
2975 | <P> | |
2976 | ||
2977 | Brace expansions may be nested. The results of each expanded | |
2978 | string are not sorted; left to right order is preserved. | |
2979 | For example, a<B>{</B>d,c,b<B>}</B>e expands into `ade ace abe'. | |
2980 | <P> | |
2981 | ||
2982 | A sequence expression takes the form | |
2983 | <B>{</B><I>x</I><B>..</B><I>y</I><B>[..</B><I>incr</I><B>]}</B>, | |
2984 | where <I>x</I> and <I>y</I> are either integers or single characters, | |
2985 | and <I>incr</I>, an optional increment, is an integer. | |
2986 | When integers are supplied, the expression expands to each number between | |
2987 | <I>x</I> and <I>y</I>, inclusive. | |
2988 | Supplied integers may be prefixed with <I>0</I> to force each term to have the | |
2989 | same width. When either <I>x</I> or y begins with a zero, the shell | |
2990 | attempts to force all generated terms to contain the same number of digits, | |
2991 | zero-padding where necessary. | |
2992 | When characters are supplied, the expression expands to each character | |
2993 | lexicographically between <I>x</I> and <I>y</I>, inclusive. Note that | |
2994 | both <I>x</I> and <I>y</I> must be of the same type. | |
2995 | When the increment is supplied, it is used as the difference between | |
2996 | each term. The default increment is 1 or -1 as appropriate. | |
2997 | <P> | |
2998 | ||
2999 | Brace expansion is performed before any other expansions, | |
3000 | and any characters special to other expansions are preserved | |
3001 | in the result. It is strictly textual. | |
3002 | <B>Bash</B> | |
3003 | ||
3004 | does not apply any syntactic interpretation to the context of the | |
3005 | expansion or the text between the braces. | |
3006 | <P> | |
3007 | ||
3008 | A correctly-formed brace expansion must contain unquoted opening | |
3009 | and closing braces, and at least one unquoted comma or a valid | |
3010 | sequence expression. | |
3011 | Any incorrectly formed brace expansion is left unchanged. | |
3012 | A <B>{</B> or <B>,</B> may be quoted with a backslash to prevent its | |
3013 | being considered part of a brace expression. | |
3014 | To avoid conflicts with parameter expansion, the string <B>${</B> | |
3015 | is not considered eligible for brace expansion. | |
3016 | <P> | |
3017 | ||
3018 | This construct is typically used as shorthand when the common | |
3019 | prefix of the strings to be generated is longer than in the | |
3020 | above example: | |
3021 | <DL COMPACT><DT><DD> | |
3022 | <P> | |
3023 | ||
3024 | mkdir /usr/local/src/bash/{old,new,dist,bugs} | |
3025 | </DL> | |
3026 | ||
3027 | or | |
3028 | <DL COMPACT><DT><DD> | |
3029 | chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}} | |
3030 | </DL> | |
3031 | ||
3032 | <P> | |
3033 | ||
3034 | Brace expansion introduces a slight incompatibility with | |
3035 | historical versions of | |
3036 | <B>sh</B>. | |
3037 | ||
3038 | <B>sh</B> | |
3039 | ||
3040 | does not treat opening or closing braces specially when they | |
3041 | appear as part of a word, and preserves them in the output. | |
3042 | <B>Bash</B> | |
3043 | ||
3044 | removes braces from words as a consequence of brace | |
3045 | expansion. For example, a word entered to | |
3046 | <B>sh</B> | |
3047 | ||
3048 | as <I>file{1,2}</I> | |
3049 | appears identically in the output. The same word is | |
3050 | output as | |
3051 | <I>file1 file2</I> | |
3052 | ||
3053 | after expansion by | |
3054 | <B>bash</B>. | |
3055 | ||
3056 | If strict compatibility with | |
3057 | <B>sh</B> | |
3058 | ||
3059 | is desired, start | |
3060 | <B>bash</B> | |
3061 | ||
3062 | with the | |
3063 | <B>+B </B> | |
3064 | ||
3065 | option or disable brace expansion with the | |
3066 | <B>+B</B> | |
3067 | ||
3068 | option to the | |
3069 | <B>set</B> | |
3070 | ||
3071 | command (see | |
3072 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
3073 | ||
3074 | </FONT> | |
3075 | below). | |
3076 | <A NAME="lbBA"> </A> | |
3077 | <H4>Tilde Expansion</H4> | |
3078 | ||
3079 | <P> | |
3080 | ||
3081 | If a word begins with an unquoted tilde character (`<B>~</B>'), all of | |
3082 | the characters preceding the first unquoted slash (or all characters, | |
3083 | if there is no unquoted slash) are considered a <I>tilde-prefix</I>. | |
3084 | If none of the characters in the tilde-prefix are quoted, the | |
3085 | characters in the tilde-prefix following the tilde are treated as a | |
3086 | possible <I>login name</I>. | |
3087 | If this login name is the null string, the tilde is replaced with the | |
3088 | value of the shell parameter | |
3089 | <FONT SIZE=-1><B>HOME</B>. | |
3090 | ||
3091 | </FONT> | |
3092 | If | |
3093 | <FONT SIZE=-1><B>HOME</B> | |
3094 | ||
3095 | </FONT> | |
3096 | is unset, the home directory of the user executing the shell is | |
3097 | substituted instead. | |
3098 | Otherwise, the tilde-prefix is replaced with the home directory | |
3099 | associated with the specified login name. | |
3100 | <P> | |
3101 | ||
3102 | If the tilde-prefix is a `~+', the value of the shell variable | |
3103 | <FONT SIZE=-1><B>PWD</B> | |
3104 | ||
3105 | </FONT> | |
3106 | replaces the tilde-prefix. | |
3107 | If the tilde-prefix is a `~-', the value of the shell variable | |
3108 | <FONT SIZE=-1><B>OLDPWD</B>, | |
3109 | ||
3110 | </FONT> | |
3111 | if it is set, is substituted. | |
3112 | If the characters following the tilde in the tilde-prefix consist | |
3113 | of a number <I>N</I>, optionally prefixed | |
3114 | by a `+' or a `-', the tilde-prefix is replaced with the corresponding | |
3115 | element from the directory stack, as it would be displayed by the | |
3116 | <B>dirs</B> | |
3117 | ||
3118 | builtin invoked with the tilde-prefix as an argument. | |
3119 | If the characters following the tilde in the tilde-prefix consist of a | |
3120 | number without a leading `+' or `-', `+' is assumed. | |
3121 | <P> | |
3122 | ||
3123 | If the login name is invalid, or the tilde expansion fails, the word | |
3124 | is unchanged. | |
3125 | <P> | |
3126 | ||
3127 | Each variable assignment is checked for unquoted tilde-prefixes immediately | |
3128 | following a | |
3129 | <B>:</B> | |
3130 | ||
3131 | or the first | |
3132 | <B>=</B>. | |
3133 | ||
3134 | In these cases, tilde expansion is also performed. | |
3135 | Consequently, one may use file names with tildes in assignments to | |
3136 | <FONT SIZE=-1><B>PATH</B>, | |
3137 | ||
3138 | </FONT> | |
3139 | <FONT SIZE=-1><B>MAILPATH</B>, | |
3140 | ||
3141 | </FONT> | |
3142 | and | |
3143 | <FONT SIZE=-1><B>CDPATH</B>, | |
3144 | ||
3145 | </FONT> | |
3146 | and the shell assigns the expanded value. | |
3147 | <A NAME="lbBB"> </A> | |
3148 | <H4>Parameter Expansion</H4> | |
3149 | ||
3150 | <P> | |
3151 | ||
3152 | The `<B>$</B>' character introduces parameter expansion, | |
3153 | command substitution, or arithmetic expansion. The parameter name | |
3154 | or symbol to be expanded may be enclosed in braces, which | |
3155 | are optional but serve to protect the variable to be expanded from | |
3156 | characters immediately following it which could be | |
3157 | interpreted as part of the name. | |
3158 | <P> | |
3159 | ||
3160 | When braces are used, the matching ending brace is the first `<B>}</B>' | |
3161 | not escaped by a backslash or within a quoted string, and not within an | |
3162 | embedded arithmetic expansion, command substitution, or parameter | |
3163 | expansion. | |
3164 | <P> | |
3165 | ||
3166 | ||
3167 | <DL COMPACT> | |
3168 | <DT>${<I>parameter</I>}<DD> | |
3169 | The value of <I>parameter</I> is substituted. The braces are required | |
3170 | when | |
3171 | <I>parameter</I> | |
3172 | ||
3173 | is a positional parameter with more than one digit, | |
3174 | or when | |
3175 | <I>parameter</I> | |
3176 | ||
3177 | is followed by a character which is not to be | |
3178 | interpreted as part of its name. | |
3179 | ||
3180 | </DL> | |
3181 | <P> | |
3182 | ||
3183 | If the first character of <I>parameter</I> is an exclamation point, | |
3184 | a level of variable indirection is introduced. | |
3185 | <B>Bash</B> uses the value of the variable formed from the rest of | |
3186 | <I>parameter</I> as the name of the variable; this variable is then | |
3187 | expanded and that value is used in the rest of the substitution, rather | |
3188 | than the value of <I>parameter</I> itself. | |
3189 | This is known as <I>indirect expansion</I>. | |
3190 | The exceptions to this are the expansions of ${!<I>prefix</I>*} and | |
3191 | ${<B>!</B><I>name</I>[<I>@</I>]} described below. | |
3192 | The exclamation point must immediately follow the left brace in order to | |
3193 | introduce indirection. | |
3194 | <P> | |
3195 | ||
3196 | In each of the cases below, <I>word</I> is subject to tilde expansion, | |
3197 | parameter expansion, command substitution, and arithmetic expansion. | |
3198 | <P> | |
3199 | ||
3200 | When not performing substring expansion, using the forms documented below, | |
3201 | <B>bash</B> tests for a parameter that is unset or null. Omitting the colon | |
3202 | results in a test only for a parameter that is unset. | |
3203 | <P> | |
3204 | ||
3205 | ||
3206 | <DL COMPACT> | |
3207 | <DT>${<I>parameter</I><B>:-</B><I>word</I>}<DD> | |
3208 | <B>Use Default Values</B>. If | |
3209 | <I>parameter</I> | |
3210 | ||
3211 | is unset or null, the expansion of | |
3212 | <I>word</I> | |
3213 | ||
3214 | is substituted. Otherwise, the value of | |
3215 | <I>parameter</I> | |
3216 | ||
3217 | is substituted. | |
3218 | <DT>${<I>parameter</I><B>:=</B><I>word</I>}<DD> | |
3219 | <B>Assign Default Values</B>. | |
3220 | If | |
3221 | <I>parameter</I> | |
3222 | ||
3223 | is unset or null, the expansion of | |
3224 | <I>word</I> | |
3225 | ||
3226 | is assigned to | |
3227 | <I>parameter</I>. | |
3228 | ||
3229 | The value of | |
3230 | <I>parameter</I> | |
3231 | ||
3232 | is then substituted. Positional parameters and special parameters may | |
3233 | not be assigned to in this way. | |
3234 | <DT>${<I>parameter</I><B>:?</B><I>word</I>}<DD> | |
3235 | <B>Display Error if Null or Unset</B>. | |
3236 | If | |
3237 | <I>parameter</I> | |
3238 | ||
3239 | is null or unset, the expansion of <I>word</I> (or a message to that effect | |
3240 | if | |
3241 | <I>word</I> | |
3242 | ||
3243 | is not present) is written to the standard error and the shell, if it | |
3244 | is not interactive, exits. Otherwise, the value of <I>parameter</I> is | |
3245 | substituted. | |
3246 | <DT>${<I>parameter</I><B>:+</B><I>word</I>}<DD> | |
3247 | <B>Use Alternate Value</B>. | |
3248 | If | |
3249 | <I>parameter</I> | |
3250 | ||
3251 | is null or unset, nothing is substituted, otherwise the expansion of | |
3252 | <I>word</I> | |
3253 | ||
3254 | is substituted. | |
3255 | <DT>${<I>parameter</I><B>:</B><I>offset</I>}<DD> | |
3256 | ||
3257 | <DT>${<I>parameter</I><B>:</B><I>offset</I><B>:</B><I>length</I>}<DD> | |
3258 | ||
3259 | <B>Substring Expansion.</B> | |
3260 | Expands to up to <I>length</I> characters of <I>parameter</I> | |
3261 | starting at the character specified by <I>offset</I>. | |
3262 | If <I>length</I> is omitted, expands to the substring of | |
3263 | <I>parameter</I> starting at the character specified by <I>offset</I>. | |
3264 | <I>length</I> and <I>offset</I> are arithmetic expressions (see | |
3265 | <FONT SIZE=-1><B>ARITHMETIC EVALUATION</B> | |
3266 | ||
3267 | </FONT> | |
3268 | below). | |
3269 | <I>length</I> must evaluate to a number greater than or equal to zero. | |
3270 | If <I>offset</I> evaluates to a number less than zero, the value | |
3271 | is used as an offset from the end of the value of <I>parameter</I>. | |
3272 | If <I>parameter</I> is <B>@</B>, the result is <I>length</I> positional | |
3273 | parameters beginning at <I>offset</I>. | |
3274 | If <I>parameter</I> is an indexed array name subscripted by @ or *, | |
3275 | the result is the <I>length</I> | |
3276 | members of the array beginning with ${<I>parameter</I>[<I>offset</I>]}. | |
3277 | A negative <I>offset</I> is taken relative to one greater than the maximum | |
3278 | index of the specified array. | |
3279 | Substring expansion applied to an associative array produces undefined | |
3280 | results. | |
3281 | Note that a negative offset must be separated from the colon by at least | |
3282 | one space to avoid being confused with the :- expansion. | |
3283 | Substring indexing is zero-based unless the positional parameters | |
3284 | are used, in which case the indexing starts at 1 by default. | |
3285 | If <I>offset</I> is 0, and the positional parameters are used, <B>$0</B> is | |
3286 | prefixed to the list. | |
3287 | <DT>${<B>!</B><I>prefix</I><B>*</B>}<DD> | |
3288 | ||
3289 | <DT>${<B>!</B><I>prefix</I><B>@</B>}<DD> | |
3290 | ||
3291 | <B>Names matching prefix.</B> | |
3292 | Expands to the names of variables whose names begin with <I>prefix</I>, | |
3293 | separated by the first character of the | |
3294 | <FONT SIZE=-1><B>IFS</B> | |
3295 | ||
3296 | </FONT> | |
3297 | special variable. | |
3298 | When <I>@</I> is used and the expansion appears within double quotes, each | |
3299 | variable name expands to a separate word. | |
3300 | <DT>${<B>!</B><I>name</I>[<I>@</I>]}<DD> | |
3301 | ||
3302 | <DT>${<B>!</B><I>name</I>[<I>*</I>]}<DD> | |
3303 | ||
3304 | <B>List of array keys.</B> | |
3305 | If <I>name</I> is an array variable, expands to the list of array indices | |
3306 | (keys) assigned in <I>name</I>. | |
3307 | If <I>name</I> is not an array, expands to 0 if <I>name</I> is set and null | |
3308 | otherwise. | |
3309 | When <I>@</I> is used and the expansion appears within double quotes, each | |
3310 | key expands to a separate word. | |
3311 | <DT>${<B>#</B><I>parameter</I>}<DD> | |
3312 | <B>Parameter length.</B> | |
3313 | The length in characters of the value of <I>parameter</I> is substituted. | |
3314 | If | |
3315 | <I>parameter</I> | |
3316 | ||
3317 | is | |
3318 | <B>*</B> | |
3319 | ||
3320 | or | |
3321 | <B>@</B>, | |
3322 | ||
3323 | the value substituted is the number of positional parameters. | |
3324 | If | |
3325 | <I>parameter</I> | |
3326 | ||
3327 | is an array name subscripted by | |
3328 | <B>*</B> | |
3329 | ||
3330 | or | |
3331 | <B>@</B>, | |
3332 | ||
3333 | the value substituted is the number of elements in the array. | |
3334 | <DT>${<I>parameter</I><B>#</B><I>word</I>}<DD> | |
3335 | ||
3336 | <DT>${<I>parameter</I><B>##</B><I>word</I>}<DD> | |
3337 | ||
3338 | <B>Remove matching prefix pattern.</B> | |
3339 | The | |
3340 | <I>word</I> | |
3341 | ||
3342 | is expanded to produce a pattern just as in pathname | |
3343 | expansion. If the pattern matches the beginning of | |
3344 | the value of | |
3345 | <I>parameter</I>, | |
3346 | ||
3347 | then the result of the expansion is the expanded value of | |
3348 | <I>parameter</I> | |
3349 | ||
3350 | with the shortest matching pattern (the ``<B>#</B>'' case) or the | |
3351 | longest matching pattern (the ``<B>##</B>'' case) deleted. | |
3352 | If | |
3353 | <I>parameter</I> | |
3354 | ||
3355 | is | |
3356 | <B>@</B> | |
3357 | ||
3358 | or | |
3359 | <B>*</B>, | |
3360 | ||
3361 | the pattern removal operation is applied to each positional | |
3362 | parameter in turn, and the expansion is the resultant list. | |
3363 | If | |
3364 | <I>parameter</I> | |
3365 | ||
3366 | is an array variable subscripted with | |
3367 | <B>@</B> | |
3368 | ||
3369 | or | |
3370 | <B>*</B>, | |
3371 | ||
3372 | the pattern removal operation is applied to each member of the | |
3373 | array in turn, and the expansion is the resultant list. | |
3374 | <DT>${<I>parameter</I><B>%</B><I>word</I>}<DD> | |
3375 | ||
3376 | <DT>${<I>parameter</I><B>%%</B><I>word</I>}<DD> | |
3377 | ||
3378 | <B>Remove matching suffix pattern.</B> | |
3379 | The <I>word</I> is expanded to produce a pattern just as in | |
3380 | pathname expansion. | |
3381 | If the pattern matches a trailing portion of the expanded value of | |
3382 | <I>parameter</I>, | |
3383 | ||
3384 | then the result of the expansion is the expanded value of | |
3385 | <I>parameter</I> | |
3386 | ||
3387 | with the shortest matching pattern (the ``<B>%</B>'' case) or the | |
3388 | longest matching pattern (the ``<B>%%</B>'' case) deleted. | |
3389 | If | |
3390 | <I>parameter</I> | |
3391 | ||
3392 | is | |
3393 | <B>@</B> | |
3394 | ||
3395 | or | |
3396 | <B>*</B>, | |
3397 | ||
3398 | the pattern removal operation is applied to each positional | |
3399 | parameter in turn, and the expansion is the resultant list. | |
3400 | If | |
3401 | <I>parameter</I> | |
3402 | ||
3403 | is an array variable subscripted with | |
3404 | <B>@</B> | |
3405 | ||
3406 | or | |
3407 | <B>*</B>, | |
3408 | ||
3409 | the pattern removal operation is applied to each member of the | |
3410 | array in turn, and the expansion is the resultant list. | |
3411 | <DT>${<I>parameter</I><B>/</B><I>pattern</I><B>/</B><I>string</I>}<DD> | |
3412 | <B>Pattern substitution.</B> | |
3413 | The <I>pattern</I> is expanded to produce a pattern just as in | |
3414 | pathname expansion. | |
3415 | <I>Parameter</I> is expanded and the longest match of <I>pattern</I> | |
3416 | against its value is replaced with <I>string</I>. | |
3417 | If <I>pattern</I> begins with <B>/</B>, all matches of <I>pattern</I> are | |
3418 | replaced with <I>string</I>. Normally only the first match is replaced. | |
3419 | If <I>pattern</I> begins with <B>#</B>, it must match at the beginning | |
3420 | of the expanded value of <I>parameter</I>. | |
3421 | If <I>pattern</I> begins with <B>%</B>, it must match at the end | |
3422 | of the expanded value of <I>parameter</I>. | |
3423 | If <I>string</I> is null, matches of <I>pattern</I> are deleted | |
3424 | and the <B>/</B> following <I>pattern</I> may be omitted. | |
3425 | If | |
3426 | <I>parameter</I> | |
3427 | ||
3428 | is | |
3429 | <B>@</B> | |
3430 | ||
3431 | or | |
3432 | <B>*</B>, | |
3433 | ||
3434 | the substitution operation is applied to each positional | |
3435 | parameter in turn, and the expansion is the resultant list. | |
3436 | If | |
3437 | <I>parameter</I> | |
3438 | ||
3439 | is an array variable subscripted with | |
3440 | <B>@</B> | |
3441 | ||
3442 | or | |
3443 | <B>*</B>, | |
3444 | ||
3445 | the substitution operation is applied to each member of the | |
3446 | array in turn, and the expansion is the resultant list. | |
3447 | <DT>${<I>parameter</I><B>^</B><I>pattern</I>}<DD> | |
3448 | ||
3449 | <DT>${<I>parameter</I><B>^^</B><I>pattern</I>}<DD> | |
3450 | <DT>${<I>parameter</I><B>,</B><I>pattern</I>}<DD> | |
3451 | <DT>${<I>parameter</I><B>,,</B><I>pattern</I>}<DD> | |
3452 | ||
3453 | <B>Case modification.</B> | |
3454 | This expansion modifies the case of alphabetic characters in <I>parameter</I>. | |
3455 | The <I>pattern</I> is expanded to produce a pattern just as in | |
3456 | pathname expansion. | |
3457 | The <B>^</B> operator converts lowercase letters matching <I>pattern</I> | |
3458 | to uppercase; the <B>,</B> operator converts matching uppercase letters | |
3459 | to lowercase. | |
3460 | The <B>^^</B> and <B>,,</B> expansions convert each matched character in the | |
3461 | expanded value; the <B>^</B> and <B>,</B> expansions match and convert only | |
3462 | the first character in the expanded value.. | |
3463 | If <I>pattern</I> is omitted, it is treated like a <B>?</B>, which matches | |
3464 | every character. | |
3465 | If | |
3466 | <I>parameter</I> | |
3467 | ||
3468 | is | |
3469 | <B>@</B> | |
3470 | ||
3471 | or | |
3472 | <B>*</B>, | |
3473 | ||
3474 | the case modification operation is applied to each positional | |
3475 | parameter in turn, and the expansion is the resultant list. | |
3476 | If | |
3477 | <I>parameter</I> | |
3478 | ||
3479 | is an array variable subscripted with | |
3480 | <B>@</B> | |
3481 | ||
3482 | or | |
3483 | <B>*</B>, | |
3484 | ||
3485 | the case modification operation is applied to each member of the | |
3486 | array in turn, and the expansion is the resultant list. | |
3487 | </DL> | |
3488 | <A NAME="lbBC"> </A> | |
3489 | <H4>Command Substitution</H4> | |
3490 | ||
3491 | <P> | |
3492 | ||
3493 | <I>Command substitution</I> allows the output of a command to replace | |
3494 | the command name. There are two forms: | |
3495 | <P> | |
3496 | ||
3497 | <DL COMPACT><DT><DD> | |
3498 | <P> | |
3499 | ||
3500 | <B>$(</B><I>command</I><B>)</B> | |
3501 | </DL> | |
3502 | ||
3503 | or | |
3504 | <DL COMPACT><DT><DD> | |
3505 | <B>`</B><I>command</I><B>`</B> | |
3506 | </DL> | |
3507 | ||
3508 | <P> | |
3509 | ||
3510 | <B>Bash</B> | |
3511 | ||
3512 | performs the expansion by executing <I>command</I> and | |
3513 | replacing the command substitution with the standard output of the | |
3514 | command, with any trailing newlines deleted. | |
3515 | Embedded newlines are not deleted, but they may be removed during | |
3516 | word splitting. | |
3517 | The command substitution <B>$(cat </B><I>file</I>) can be replaced by | |
3518 | the equivalent but faster <B>$(< </B><I>file</I>). | |
3519 | <P> | |
3520 | ||
3521 | When the old-style backquote form of substitution is used, | |
3522 | backslash retains its literal meaning except when followed by | |
3523 | <B>$</B>, | |
3524 | ||
3525 | <B>`</B>, | |
3526 | ||
3527 | or | |
3528 | <B>\</B>. | |
3529 | ||
3530 | The first backquote not preceded by a backslash terminates the | |
3531 | command substitution. | |
3532 | When using the $(<I>command</I>) form, all characters between the | |
3533 | parentheses make up the command; none are treated specially. | |
3534 | <P> | |
3535 | ||
3536 | Command substitutions may be nested. To nest when using the backquoted form, | |
3537 | escape the inner backquotes with backslashes. | |
3538 | <P> | |
3539 | ||
3540 | If the substitution appears within double quotes, word splitting and | |
3541 | pathname expansion are not performed on the results. | |
3542 | <A NAME="lbBD"> </A> | |
3543 | <H4>Arithmetic Expansion</H4> | |
3544 | ||
3545 | <P> | |
3546 | ||
3547 | Arithmetic expansion allows the evaluation of an arithmetic expression | |
3548 | and the substitution of the result. The format for arithmetic expansion is: | |
3549 | <DL COMPACT><DT><DD> | |
3550 | <P> | |
3551 | ||
3552 | <B>$((</B><I>expression</I><B>))</B> | |
3553 | </DL> | |
3554 | ||
3555 | <P> | |
3556 | ||
3557 | The | |
3558 | <I>expression</I> | |
3559 | ||
3560 | is treated as if it were within double quotes, but a double quote | |
3561 | inside the parentheses is not treated specially. | |
3562 | All tokens in the expression undergo parameter expansion, string | |
3563 | expansion, command substitution, and quote removal. | |
3564 | Arithmetic expansions may be nested. | |
3565 | <P> | |
3566 | ||
3567 | The evaluation is performed according to the rules listed below under | |
3568 | <FONT SIZE=-1><B>ARITHMETIC EVALUATION</B>. | |
3569 | ||
3570 | </FONT> | |
3571 | If | |
3572 | <I>expression</I> | |
3573 | ||
3574 | is invalid, | |
3575 | <B>bash</B> | |
3576 | ||
3577 | prints a message indicating failure and no substitution occurs. | |
3578 | <A NAME="lbBE"> </A> | |
3579 | <H4>Process Substitution</H4> | |
3580 | ||
3581 | <P> | |
3582 | ||
3583 | <I>Process substitution</I> is supported on systems that support named | |
3584 | pipes (<I>FIFOs</I>) or the <B>/dev/fd</B> method of naming open files. | |
3585 | It takes the form of | |
3586 | <B><(</B><I>list</I><B>)</B> | |
3587 | or | |
3588 | <B>>(</B><I>list</I><B>)</B>. | |
3589 | The process <I>list</I> is run with its input or output connected to a | |
3590 | <I>FIFO</I> or some file in <B>/dev/fd</B>. The name of this file is | |
3591 | passed as an argument to the current command as the result of the | |
3592 | expansion. If the <B>>(</B><I>list</I><B>)</B> form is used, writing to | |
3593 | the file will provide input for <I>list</I>. If the | |
3594 | <B><(</B><I>list</I><B>)</B> form is used, the file passed as an | |
3595 | argument should be read to obtain the output of <I>list</I>. | |
3596 | <P> | |
3597 | ||
3598 | When available, process substitution is performed | |
3599 | simultaneously with parameter and variable expansion, | |
3600 | command substitution, | |
3601 | and arithmetic expansion. | |
3602 | <A NAME="lbBF"> </A> | |
3603 | <H4>Word Splitting</H4> | |
3604 | ||
3605 | <P> | |
3606 | ||
3607 | The shell scans the results of | |
3608 | parameter expansion, | |
3609 | command substitution, | |
3610 | and | |
3611 | arithmetic expansion | |
3612 | that did not occur within double quotes for | |
3613 | <I>word splitting</I>. | |
3614 | ||
3615 | <P> | |
3616 | ||
3617 | The shell treats each character of | |
3618 | <FONT SIZE=-1><B>IFS</B> | |
3619 | ||
3620 | </FONT> | |
3621 | as a delimiter, and splits the results of the other | |
3622 | expansions into words on these characters. If | |
3623 | <FONT SIZE=-1><B>IFS</B> | |
3624 | ||
3625 | </FONT> | |
3626 | is unset, or its | |
3627 | value is exactly | |
3628 | <B><space><tab><newline></B>, | |
3629 | ||
3630 | the default, then | |
3631 | sequences of | |
3632 | <B><space></B>, | |
3633 | ||
3634 | <B><tab></B>, | |
3635 | ||
3636 | and | |
3637 | <B><newline></B> | |
3638 | ||
3639 | at the beginning and end of the results of the previous | |
3640 | expansions are ignored, and | |
3641 | any sequence of | |
3642 | <FONT SIZE=-1><B>IFS</B> | |
3643 | ||
3644 | </FONT> | |
3645 | characters not at the beginning or end serves to delimit words. | |
3646 | If | |
3647 | <FONT SIZE=-1><B>IFS</B> | |
3648 | ||
3649 | </FONT> | |
3650 | has a value other than the default, then sequences of | |
3651 | the whitespace characters | |
3652 | <B>space</B> | |
3653 | ||
3654 | and | |
3655 | <B>tab</B> | |
3656 | ||
3657 | are ignored at the beginning and end of the | |
3658 | word, as long as the whitespace character is in the | |
3659 | value of | |
3660 | <FONT SIZE=-1><B>IFS</B> | |
3661 | ||
3662 | </FONT> | |
3663 | (an | |
3664 | <FONT SIZE=-1><B>IFS</B> | |
3665 | ||
3666 | </FONT> | |
3667 | whitespace character). | |
3668 | Any character in | |
3669 | <FONT SIZE=-1><B>IFS</B> | |
3670 | ||
3671 | </FONT> | |
3672 | that is not | |
3673 | <FONT SIZE=-1><B>IFS</B> | |
3674 | ||
3675 | </FONT> | |
3676 | whitespace, along with any adjacent | |
3677 | <FONT SIZE=-1><B>IFS</B> | |
3678 | ||
3679 | </FONT> | |
3680 | whitespace characters, delimits a field. | |
3681 | A sequence of | |
3682 | <FONT SIZE=-1><B>IFS</B> | |
3683 | ||
3684 | </FONT> | |
3685 | whitespace characters is also treated as a delimiter. | |
3686 | If the value of | |
3687 | <FONT SIZE=-1><B>IFS</B> | |
3688 | ||
3689 | </FONT> | |
3690 | is null, no word splitting occurs. | |
3691 | <P> | |
3692 | ||
3693 | Explicit null arguments (<B>""</B> or <B>aqaq</B>) are retained. | |
3694 | Unquoted implicit null arguments, resulting from the expansion of | |
3695 | parameters that have no values, are removed. | |
3696 | If a parameter with no value is expanded within double quotes, a | |
3697 | null argument results and is retained. | |
3698 | <P> | |
3699 | ||
3700 | Note that if no expansion occurs, no splitting | |
3701 | is performed. | |
3702 | <A NAME="lbBG"> </A> | |
3703 | <H4>Pathname Expansion</H4> | |
3704 | ||
3705 | <P> | |
3706 | ||
3707 | After word splitting, | |
3708 | unless the | |
3709 | <B>-f</B> | |
3710 | ||
3711 | option has been set, | |
3712 | <B>bash</B> | |
3713 | ||
3714 | scans each word for the characters | |
3715 | <B>*</B>, | |
3716 | ||
3717 | <B>?</B>, | |
3718 | ||
3719 | and | |
3720 | <B>[</B>. | |
3721 | ||
3722 | If one of these characters appears, then the word is | |
3723 | regarded as a | |
3724 | <I>pattern</I>, | |
3725 | ||
3726 | and replaced with an alphabetically sorted list of | |
3727 | file names matching the pattern. | |
3728 | If no matching file names are found, | |
3729 | and the shell option | |
3730 | <B>nullglob</B> | |
3731 | ||
3732 | is not enabled, the word is left unchanged. | |
3733 | If the | |
3734 | <B>nullglob</B> | |
3735 | ||
3736 | option is set, and no matches are found, | |
3737 | the word is removed. | |
3738 | If the | |
3739 | <B>failglob</B> | |
3740 | ||
3741 | shell option is set, and no matches are found, an error message | |
3742 | is printed and the command is not executed. | |
3743 | If the shell option | |
3744 | <B>nocaseglob</B> | |
3745 | ||
3746 | is enabled, the match is performed without regard to the case | |
3747 | of alphabetic characters. | |
3748 | When a pattern is used for pathname expansion, | |
3749 | the character | |
3750 | <B>``.''</B> | |
3751 | ||
3752 | at the start of a name or immediately following a slash | |
3753 | must be matched explicitly, unless the shell option | |
3754 | <B>dotglob</B> | |
3755 | ||
3756 | is set. | |
3757 | When matching a pathname, the slash character must always be | |
3758 | matched explicitly. | |
3759 | In other cases, the | |
3760 | <B>``.''</B> | |
3761 | ||
3762 | character is not treated specially. | |
3763 | See the description of | |
3764 | <B>shopt</B> | |
3765 | ||
3766 | below under | |
3767 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
3768 | ||
3769 | </FONT> | |
3770 | for a description of the | |
3771 | <B>nocaseglob</B>, | |
3772 | ||
3773 | <B>nullglob</B>, | |
3774 | ||
3775 | <B>failglob</B>, | |
3776 | ||
3777 | and | |
3778 | <B>dotglob</B> | |
3779 | ||
3780 | shell options. | |
3781 | <P> | |
3782 | ||
3783 | The | |
3784 | <FONT SIZE=-1><B>GLOBIGNORE</B> | |
3785 | ||
3786 | </FONT> | |
3787 | shell variable may be used to restrict the set of file names matching a | |
3788 | <I>pattern</I>. | |
3789 | ||
3790 | If | |
3791 | <FONT SIZE=-1><B>GLOBIGNORE</B> | |
3792 | ||
3793 | </FONT> | |
3794 | is set, each matching file name that also matches one of the patterns in | |
3795 | <FONT SIZE=-1><B>GLOBIGNORE</B> | |
3796 | ||
3797 | </FONT> | |
3798 | is removed from the list of matches. | |
3799 | The file names | |
3800 | <B>``.''</B> | |
3801 | ||
3802 | and | |
3803 | <B>``..''</B> | |
3804 | ||
3805 | are always ignored when | |
3806 | <FONT SIZE=-1><B>GLOBIGNORE</B> | |
3807 | ||
3808 | </FONT> | |
3809 | is set and not null. However, setting | |
3810 | <FONT SIZE=-1><B>GLOBIGNORE</B> | |
3811 | ||
3812 | </FONT> | |
3813 | to a non-null value has the effect of enabling the | |
3814 | <B>dotglob</B> | |
3815 | ||
3816 | shell option, so all other file names beginning with a | |
3817 | <B>``.''</B> | |
3818 | ||
3819 | will match. | |
3820 | To get the old behavior of ignoring file names beginning with a | |
3821 | <B>``.''</B>, | |
3822 | ||
3823 | make | |
3824 | <B>``.*''</B> | |
3825 | ||
3826 | one of the patterns in | |
3827 | <FONT SIZE=-1><B>GLOBIGNORE</B>. | |
3828 | ||
3829 | </FONT> | |
3830 | The | |
3831 | <B>dotglob</B> | |
3832 | ||
3833 | option is disabled when | |
3834 | <FONT SIZE=-1><B>GLOBIGNORE</B> | |
3835 | ||
3836 | </FONT> | |
3837 | is unset. | |
3838 | <P> | |
3839 | ||
3840 | <B>Pattern Matching</B> | |
3841 | <P> | |
3842 | ||
3843 | Any character that appears in a pattern, other than the special pattern | |
3844 | characters described below, matches itself. The NUL character may not | |
3845 | occur in a pattern. A backslash escapes the following character; the | |
3846 | escaping backslash is discarded when matching. | |
3847 | The special pattern characters must be quoted if | |
3848 | they are to be matched literally. | |
3849 | <P> | |
3850 | ||
3851 | The special pattern characters have the following meanings: | |
3852 | <P> | |
3853 | ||
3854 | ||
3855 | <DL COMPACT> | |
3856 | <DT><B>*</B> | |
3857 | ||
3858 | <DD> | |
3859 | Matches any string, including the null string. | |
3860 | When the <B>globstar</B> shell option is enabled, and <B>*</B> is used in | |
3861 | a filename expansion context, two adjacent <B>*</B>s used as a single | |
3862 | pattern will match all files and zero or more directories and | |
3863 | subdirectories. | |
3864 | If followed by a <B>/</B>, two adjacent <B>*</B>s will match only directories | |
3865 | and subdirectories. | |
3866 | <DT><B>?</B> | |
3867 | ||
3868 | <DD> | |
3869 | Matches any single character. | |
3870 | <DT><B>[...]</B> | |
3871 | ||
3872 | <DD> | |
3873 | Matches any one of the enclosed characters. A pair of characters | |
3874 | separated by a hyphen denotes a | |
3875 | <I>range expression</I>; | |
3876 | any character that sorts between those two characters, inclusive, | |
3877 | using the current locale's collating sequence and character set, | |
3878 | is matched. If the first character following the | |
3879 | <B>[</B> | |
3880 | ||
3881 | is a | |
3882 | <B>!</B> | |
3883 | ||
3884 | or a | |
3885 | <B>^</B> | |
3886 | ||
3887 | then any character not enclosed is matched. | |
3888 | The sorting order of characters in range expressions is determined by | |
3889 | the current locale and the value of the <B>LC_COLLATE</B> shell variable, | |
3890 | if set. | |
3891 | A | |
3892 | <B>-</B> | |
3893 | ||
3894 | may be matched by including it as the first or last character | |
3895 | in the set. | |
3896 | A | |
3897 | <B>]</B> | |
3898 | ||
3899 | may be matched by including it as the first character | |
3900 | in the set. | |
3901 | <BR> | |
3902 | ||
3903 | <P> | |
3904 | ||
3905 | ||
3906 | Within | |
3907 | <B>[</B> | |
3908 | ||
3909 | and | |
3910 | <B>]</B>, | |
3911 | ||
3912 | <I>character classes</I> can be specified using the syntax | |
3913 | <B>[:</B><I>class</I><B>:]</B>, where <I>class</I> is one of the | |
3914 | following classes defined in the POSIX standard: | |
3915 | </DL> | |
3916 | <P> | |
3917 | ||
3918 | <DL COMPACT><DT><DD> | |
3919 | <B> | |
3920 | </B> | |
3921 | ||
3922 | alnum alpha ascii blank cntrl digit graph lower print punct space upper word xdigit | |
3923 | <BR> | |
3924 | ||
3925 | A character class matches any character belonging to that class. | |
3926 | The <B>word</B> character class matches letters, digits, and the character _. | |
3927 | <BR> | |
3928 | ||
3929 | <P> | |
3930 | ||
3931 | ||
3932 | Within | |
3933 | <B>[</B> | |
3934 | ||
3935 | and | |
3936 | <B>]</B>, | |
3937 | ||
3938 | an <I>equivalence class</I> can be specified using the syntax | |
3939 | <B>[=</B><I>c</I><B>=]</B>, which matches all characters with the | |
3940 | same collation weight (as defined by the current locale) as | |
3941 | the character <I>c</I>. | |
3942 | <BR> | |
3943 | ||
3944 | <P> | |
3945 | ||
3946 | ||
3947 | Within | |
3948 | <B>[</B> | |
3949 | ||
3950 | and | |
3951 | <B>]</B>, | |
3952 | ||
3953 | the syntax <B>[.</B><I>symbol</I><B>.]</B> matches the collating symbol | |
3954 | <I>symbol</I>. | |
3955 | </DL> | |
3956 | ||
3957 | ||
3958 | <P> | |
3959 | ||
3960 | If the <B>extglob</B> shell option is enabled using the <B>shopt</B> | |
3961 | builtin, several extended pattern matching operators are recognized. | |
3962 | In the following description, a <I>pattern-list</I> is a list of one | |
3963 | or more patterns separated by a <B>|</B>. | |
3964 | Composite patterns may be formed using one or more of the following | |
3965 | sub-patterns: | |
3966 | <P> | |
3967 | ||
3968 | <DL COMPACT><DT><DD> | |
3969 | <DL COMPACT> | |
3970 | <DT><B>?(</B><I>pattern-list</I><B>)</B><DD> | |
3971 | Matches zero or one occurrence of the given patterns | |
3972 | <DT><B>*(</B><I>pattern-list</I><B>)</B><DD> | |
3973 | Matches zero or more occurrences of the given patterns | |
3974 | <DT><B>+(</B><I>pattern-list</I><B>)</B><DD> | |
3975 | Matches one or more occurrences of the given patterns | |
3976 | <DT><B>@(</B><I>pattern-list</I><B>)</B><DD> | |
3977 | Matches one of the given patterns | |
3978 | <DT><B>!(</B><I>pattern-list</I><B>)</B><DD> | |
3979 | Matches anything except one of the given patterns | |
3980 | </DL></DL> | |
3981 | ||
3982 | ||
3983 | <A NAME="lbBH"> </A> | |
3984 | <H4>Quote Removal</H4> | |
3985 | ||
3986 | <P> | |
3987 | ||
3988 | After the preceding expansions, all unquoted occurrences of the | |
3989 | characters | |
3990 | <B>\</B>, | |
3991 | ||
3992 | <B>aq</B>, | |
3993 | ||
3994 | and <B>"</B> that did not result from one of the above | |
3995 | expansions are removed. | |
3996 | <A NAME="lbBI"> </A> | |
3997 | <H3>REDIRECTION</H3> | |
3998 | ||
3999 | Before a command is executed, its input and output | |
4000 | may be | |
4001 | <I>redirected</I> | |
4002 | ||
4003 | using a special notation interpreted by the shell. | |
4004 | Redirection may also be used to open and close files for the | |
4005 | current shell execution environment. The following redirection | |
4006 | operators may precede or appear anywhere within a | |
4007 | <I>simple command</I> | |
4008 | ||
4009 | or may follow a | |
4010 | <I>command</I>. | |
4011 | ||
4012 | Redirections are processed in the order they appear, from | |
4013 | left to right. | |
4014 | <P> | |
4015 | ||
4016 | In the following descriptions, if the file descriptor number is | |
4017 | omitted, and the first character of the redirection operator is | |
4018 | <B><</B>, | |
4019 | ||
4020 | the redirection refers to the standard input (file descriptor | |
4021 | 0). If the first character of the redirection operator is | |
4022 | <B>></B>, | |
4023 | ||
4024 | the redirection refers to the standard output (file descriptor | |
4025 | 1). | |
4026 | <P> | |
4027 | ||
4028 | The word following the redirection operator in the following | |
4029 | descriptions, unless otherwise noted, is subjected to brace expansion, | |
4030 | tilde expansion, parameter expansion, command substitution, arithmetic | |
4031 | expansion, quote removal, pathname expansion, and word splitting. | |
4032 | If it expands to more than one word, | |
4033 | <B>bash</B> | |
4034 | ||
4035 | reports an error. | |
4036 | <P> | |
4037 | ||
4038 | Note that the order of redirections is significant. For example, | |
4039 | the command | |
4040 | <DL COMPACT><DT><DD> | |
4041 | <P> | |
4042 | ||
4043 | ls <B>></B> dirlist 2<B>>&</B>1 | |
4044 | </DL> | |
4045 | ||
4046 | <P> | |
4047 | ||
4048 | directs both standard output and standard error to the file | |
4049 | <I>dirlist</I>, | |
4050 | ||
4051 | while the command | |
4052 | <DL COMPACT><DT><DD> | |
4053 | <P> | |
4054 | ||
4055 | ls 2<B>>&</B>1 <B>></B> dirlist | |
4056 | </DL> | |
4057 | ||
4058 | <P> | |
4059 | ||
4060 | directs only the standard output to file | |
4061 | <I>dirlist</I>, | |
4062 | ||
4063 | because the standard error was duplicated as standard output | |
4064 | before the standard output was redirected to | |
4065 | <I>dirlist</I>. | |
4066 | ||
4067 | <P> | |
4068 | ||
4069 | <B>Bash</B> handles several filenames specially when they are used in | |
4070 | redirections, as described in the following table: | |
4071 | <DL COMPACT><DT><DD> | |
4072 | <P> | |
4073 | ||
4074 | ||
4075 | <DL COMPACT> | |
4076 | <DT><B>/dev/fd/</B><I>fd</I> | |
4077 | ||
4078 | <DD> | |
4079 | If <I>fd</I> is a valid integer, file descriptor <I>fd</I> is duplicated. | |
4080 | <DT><B>/dev/stdin</B> | |
4081 | ||
4082 | <DD> | |
4083 | File descriptor 0 is duplicated. | |
4084 | <DT><B>/dev/stdout</B> | |
4085 | ||
4086 | <DD> | |
4087 | File descriptor 1 is duplicated. | |
4088 | <DT><B>/dev/stderr</B> | |
4089 | ||
4090 | <DD> | |
4091 | File descriptor 2 is duplicated. | |
4092 | <DT><B>/dev/tcp/</B><I>host</I>/<I>port</I> | |
4093 | ||
4094 | <DD> | |
4095 | If <I>host</I> is a valid hostname or Internet address, and <I>port</I> | |
4096 | is an integer port number or service name, <B>bash</B> attempts to open | |
4097 | a TCP connection to the corresponding socket. | |
4098 | <DT><B>/dev/udp/</B><I>host</I>/<I>port</I> | |
4099 | ||
4100 | <DD> | |
4101 | If <I>host</I> is a valid hostname or Internet address, and <I>port</I> | |
4102 | is an integer port number or service name, <B>bash</B> attempts to open | |
4103 | a UDP connection to the corresponding socket. | |
4104 | ||
4105 | </DL></DL> | |
4106 | ||
4107 | <P> | |
4108 | ||
4109 | A failure to open or create a file causes the redirection to fail. | |
4110 | <P> | |
4111 | ||
4112 | Redirections using file descriptors greater than 9 should be used with | |
4113 | care, as they may conflict with file descriptors the shell uses | |
4114 | internally. | |
4115 | <A NAME="lbBJ"> </A> | |
4116 | <H4>Redirecting Input</H4> | |
4117 | ||
4118 | <P> | |
4119 | ||
4120 | Redirection of input causes the file whose name results from | |
4121 | the expansion of | |
4122 | <I>word</I> | |
4123 | ||
4124 | to be opened for reading on file descriptor | |
4125 | <I>n</I>, | |
4126 | ||
4127 | or the standard input (file descriptor 0) if | |
4128 | <I>n</I> | |
4129 | ||
4130 | is not specified. | |
4131 | <P> | |
4132 | ||
4133 | The general format for redirecting input is: | |
4134 | <DL COMPACT><DT><DD> | |
4135 | <P> | |
4136 | ||
4137 | [<I>n</I>]<B><</B><I>word</I> | |
4138 | </DL> | |
4139 | ||
4140 | <A NAME="lbBK"> </A> | |
4141 | <H4>Redirecting Output</H4> | |
4142 | ||
4143 | <P> | |
4144 | ||
4145 | Redirection of output causes the file whose name results from | |
4146 | the expansion of | |
4147 | <I>word</I> | |
4148 | ||
4149 | to be opened for writing on file descriptor | |
4150 | <I>n</I>, | |
4151 | ||
4152 | or the standard output (file descriptor 1) if | |
4153 | <I>n</I> | |
4154 | ||
4155 | is not specified. If the file does not exist it is created; | |
4156 | if it does exist it is truncated to zero size. | |
4157 | <P> | |
4158 | ||
4159 | The general format for redirecting output is: | |
4160 | <DL COMPACT><DT><DD> | |
4161 | <P> | |
4162 | ||
4163 | [<I>n</I>]<B>></B><I>word</I> | |
4164 | </DL> | |
4165 | ||
4166 | <P> | |
4167 | ||
4168 | If the redirection operator is | |
4169 | <B>></B>, | |
4170 | ||
4171 | and the | |
4172 | <B>noclobber</B> | |
4173 | ||
4174 | option to the | |
4175 | <B>set</B> | |
4176 | ||
4177 | builtin has been enabled, the redirection will fail if the file | |
4178 | whose name results from the expansion of <I>word</I> exists and is | |
4179 | a regular file. | |
4180 | If the redirection operator is | |
4181 | <B>>|</B>, | |
4182 | ||
4183 | or the redirection operator is | |
4184 | <B>></B> | |
4185 | ||
4186 | and the | |
4187 | <B>noclobber</B> | |
4188 | ||
4189 | option to the | |
4190 | <B>set</B> | |
4191 | ||
4192 | builtin command is not enabled, the redirection is attempted even | |
4193 | if the file named by <I>word</I> exists. | |
4194 | <A NAME="lbBL"> </A> | |
4195 | <H4>Appending Redirected Output</H4> | |
4196 | ||
4197 | <P> | |
4198 | ||
4199 | Redirection of output in this fashion | |
4200 | causes the file whose name results from | |
4201 | the expansion of | |
4202 | <I>word</I> | |
4203 | ||
4204 | to be opened for appending on file descriptor | |
4205 | <I>n</I>, | |
4206 | ||
4207 | or the standard output (file descriptor 1) if | |
4208 | <I>n</I> | |
4209 | ||
4210 | is not specified. If the file does not exist it is created. | |
4211 | <P> | |
4212 | ||
4213 | The general format for appending output is: | |
4214 | <DL COMPACT><DT><DD> | |
4215 | <P> | |
4216 | ||
4217 | [<I>n</I>]<B>>></B><I>word</I> | |
4218 | </DL> | |
4219 | ||
4220 | <P> | |
4221 | ||
4222 | <A NAME="lbBM"> </A> | |
4223 | <H4>Redirecting Standard Output and Standard Error</H4> | |
4224 | ||
4225 | <P> | |
4226 | ||
4227 | This construct allows both the | |
4228 | standard output (file descriptor 1) and | |
4229 | the standard error output (file descriptor 2) | |
4230 | to be redirected to the file whose name is the | |
4231 | expansion of | |
4232 | <I>word</I>. | |
4233 | ||
4234 | <P> | |
4235 | ||
4236 | There are two formats for redirecting standard output and | |
4237 | standard error: | |
4238 | <DL COMPACT><DT><DD> | |
4239 | <P> | |
4240 | ||
4241 | <B>&></B><I>word</I> | |
4242 | </DL> | |
4243 | ||
4244 | and | |
4245 | <DL COMPACT><DT><DD> | |
4246 | <B>>&</B><I>word</I> | |
4247 | </DL> | |
4248 | ||
4249 | <P> | |
4250 | ||
4251 | Of the two forms, the first is preferred. | |
4252 | This is semantically equivalent to | |
4253 | <DL COMPACT><DT><DD> | |
4254 | <P> | |
4255 | ||
4256 | <B>></B><I>word</I> 2<B>>&</B>1 | |
4257 | </DL> | |
4258 | ||
4259 | <P> | |
4260 | ||
4261 | <A NAME="lbBN"> </A> | |
4262 | <H4>Appending Standard Output and Standard Error</H4> | |
4263 | ||
4264 | <P> | |
4265 | ||
4266 | This construct allows both the | |
4267 | standard output (file descriptor 1) and | |
4268 | the standard error output (file descriptor 2) | |
4269 | to be appended to the file whose name is the | |
4270 | expansion of | |
4271 | <I>word</I>. | |
4272 | ||
4273 | <P> | |
4274 | ||
4275 | The format for appending standard output and standard error is: | |
4276 | <DL COMPACT><DT><DD> | |
4277 | <P> | |
4278 | ||
4279 | <B>&>></B><I>word</I> | |
4280 | </DL> | |
4281 | ||
4282 | <P> | |
4283 | ||
4284 | This is semantically equivalent to | |
4285 | <DL COMPACT><DT><DD> | |
4286 | <P> | |
4287 | ||
4288 | <B>>></B><I>word</I> 2<B>>&</B>1 | |
4289 | </DL> | |
4290 | ||
4291 | <A NAME="lbBO"> </A> | |
4292 | <H4>Here Documents</H4> | |
4293 | ||
4294 | <P> | |
4295 | ||
4296 | This type of redirection instructs the shell to read input from the | |
4297 | current source until a line containing only | |
4298 | <I>delimiter</I> | |
4299 | ||
4300 | (with no trailing blanks) | |
4301 | is seen. All of | |
4302 | the lines read up to that point are then used as the standard | |
4303 | input for a command. | |
4304 | <P> | |
4305 | ||
4306 | The format of here-documents is: | |
4307 | <DL COMPACT><DT><DD> | |
4308 | <P> | |
4309 | ||
4310 | <PRE> | |
4311 | <B><<</B>[<B>-</B>]<I>word</I> | |
4312 | <I>here-document</I> | |
4313 | <I>delimiter</I> | |
4314 | </PRE> | |
4315 | ||
4316 | </DL> | |
4317 | ||
4318 | <P> | |
4319 | ||
4320 | No parameter expansion, command substitution, arithmetic expansion, | |
4321 | or pathname expansion is performed on | |
4322 | <I>word</I>. | |
4323 | ||
4324 | If any characters in | |
4325 | <I>word</I> | |
4326 | ||
4327 | are quoted, the | |
4328 | <I>delimiter</I> | |
4329 | ||
4330 | is the result of quote removal on | |
4331 | <I>word</I>, | |
4332 | ||
4333 | and the lines in the here-document are not expanded. | |
4334 | If <I>word</I> is unquoted, | |
4335 | all lines of the here-document are subjected to parameter expansion, | |
4336 | command substitution, and arithmetic expansion. In the latter | |
4337 | case, the character sequence | |
4338 | <B>\<newline></B> | |
4339 | ||
4340 | is ignored, and | |
4341 | <B>\</B> | |
4342 | ||
4343 | must be used to quote the characters | |
4344 | <B>\</B>, | |
4345 | ||
4346 | <B>$</B>, | |
4347 | ||
4348 | and | |
4349 | <B>`</B>. | |
4350 | ||
4351 | <P> | |
4352 | ||
4353 | If the redirection operator is | |
4354 | <B><<-</B>, | |
4355 | ||
4356 | then all leading tab characters are stripped from input lines and the | |
4357 | line containing | |
4358 | <I>delimiter</I>. | |
4359 | ||
4360 | This allows | |
4361 | here-documents within shell scripts to be indented in a | |
4362 | natural fashion. | |
4363 | <A NAME="lbBP"> </A> | |
4364 | <H4>Here Strings</H4> | |
4365 | ||
4366 | A variant of here documents, the format is: | |
4367 | <DL COMPACT><DT><DD> | |
4368 | <P> | |
4369 | ||
4370 | <PRE> | |
4371 | <B><<<</B><I>word</I> | |
4372 | </PRE> | |
4373 | ||
4374 | </DL> | |
4375 | ||
4376 | <P> | |
4377 | ||
4378 | The <I>word</I> is expanded and supplied to the command on its standard | |
4379 | input. | |
4380 | <A NAME="lbBQ"> </A> | |
4381 | <H4>Duplicating File Descriptors</H4> | |
4382 | ||
4383 | <P> | |
4384 | ||
4385 | The redirection operator | |
4386 | <DL COMPACT><DT><DD> | |
4387 | <P> | |
4388 | ||
4389 | [<I>n</I>]<B><&</B><I>word</I> | |
4390 | </DL> | |
4391 | ||
4392 | <P> | |
4393 | ||
4394 | is used to duplicate input file descriptors. | |
4395 | If | |
4396 | <I>word</I> | |
4397 | ||
4398 | expands to one or more digits, the file descriptor denoted by | |
4399 | <I>n</I> | |
4400 | ||
4401 | is made to be a copy of that file descriptor. | |
4402 | If the digits in | |
4403 | <I>word</I> | |
4404 | ||
4405 | do not specify a file descriptor open for input, a redirection error occurs. | |
4406 | If | |
4407 | <I>word</I> | |
4408 | ||
4409 | evaluates to | |
4410 | <B>-</B>, | |
4411 | ||
4412 | file descriptor | |
4413 | <I>n</I> | |
4414 | ||
4415 | is closed. If | |
4416 | <I>n</I> | |
4417 | ||
4418 | is not specified, the standard input (file descriptor 0) is used. | |
4419 | <P> | |
4420 | ||
4421 | The operator | |
4422 | <DL COMPACT><DT><DD> | |
4423 | <P> | |
4424 | ||
4425 | [<I>n</I>]<B>>&</B><I>word</I> | |
4426 | </DL> | |
4427 | ||
4428 | <P> | |
4429 | ||
4430 | is used similarly to duplicate output file descriptors. If | |
4431 | <I>n</I> | |
4432 | ||
4433 | is not specified, the standard output (file descriptor 1) is used. | |
4434 | If the digits in | |
4435 | <I>word</I> | |
4436 | ||
4437 | do not specify a file descriptor open for output, a redirection error occurs. | |
4438 | As a special case, if <I>n</I> is omitted, and <I>word</I> does not | |
4439 | expand to one or more digits, the standard output and standard | |
4440 | error are redirected as described previously. | |
4441 | <A NAME="lbBR"> </A> | |
4442 | <H4>Moving File Descriptors</H4> | |
4443 | ||
4444 | <P> | |
4445 | ||
4446 | The redirection operator | |
4447 | <DL COMPACT><DT><DD> | |
4448 | <P> | |
4449 | ||
4450 | [<I>n</I>]<B><&</B><I>digit</I><B>-</B> | |
4451 | </DL> | |
4452 | ||
4453 | <P> | |
4454 | ||
4455 | moves the file descriptor <I>digit</I> to file descriptor | |
4456 | <I>n</I>, | |
4457 | ||
4458 | or the standard input (file descriptor 0) if <I>n</I> is not specified. | |
4459 | <I>digit</I> is closed after being duplicated to <I>n</I>. | |
4460 | <P> | |
4461 | ||
4462 | Similarly, the redirection operator | |
4463 | <DL COMPACT><DT><DD> | |
4464 | <P> | |
4465 | ||
4466 | [<I>n</I>]<B>>&</B><I>digit</I><B>-</B> | |
4467 | </DL> | |
4468 | ||
4469 | <P> | |
4470 | ||
4471 | moves the file descriptor <I>digit</I> to file descriptor | |
4472 | <I>n</I>, | |
4473 | ||
4474 | or the standard output (file descriptor 1) if <I>n</I> is not specified. | |
4475 | <A NAME="lbBS"> </A> | |
4476 | <H4>Opening File Descriptors for Reading and Writing</H4> | |
4477 | ||
4478 | <P> | |
4479 | ||
4480 | The redirection operator | |
4481 | <DL COMPACT><DT><DD> | |
4482 | <P> | |
4483 | ||
4484 | [<I>n</I>]<B><></B><I>word</I> | |
4485 | </DL> | |
4486 | ||
4487 | <P> | |
4488 | ||
4489 | causes the file whose name is the expansion of | |
4490 | <I>word</I> | |
4491 | ||
4492 | to be opened for both reading and writing on file descriptor | |
4493 | <I>n</I>, | |
4494 | ||
4495 | or on file descriptor 0 if | |
4496 | <I>n</I> | |
4497 | ||
4498 | is not specified. If the file does not exist, it is created. | |
4499 | <A NAME="lbBT"> </A> | |
4500 | <H3>ALIASES</H3> | |
4501 | ||
4502 | <I>Aliases</I> allow a string to be substituted for a word when it is used | |
4503 | as the first word of a simple command. | |
4504 | The shell maintains a list of aliases that may be set and unset with the | |
4505 | <B>alias</B> | |
4506 | ||
4507 | and | |
4508 | <B>unalias</B> | |
4509 | ||
4510 | builtin commands (see | |
4511 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
4512 | ||
4513 | </FONT> | |
4514 | below). | |
4515 | The first word of each simple command, if unquoted, | |
4516 | is checked to see if it has an | |
4517 | alias. If so, that word is replaced by the text of the alias. | |
4518 | The characters <B>/</B>, <B>$</B>, <B>`</B>, and <B>=</B> and | |
4519 | any of the shell <I>metacharacters</I> or quoting characters | |
4520 | listed above may not appear in an alias name. | |
4521 | The replacement text may contain any valid shell input, | |
4522 | including shell metacharacters. | |
4523 | The first word of the replacement text is tested | |
4524 | for aliases, but a word that is identical to an alias being expanded | |
4525 | is not expanded a second time. | |
4526 | This means that one may alias | |
4527 | <B>ls</B> | |
4528 | ||
4529 | to | |
4530 | <B>ls -F</B>, | |
4531 | ||
4532 | for instance, and | |
4533 | <B>bash</B> | |
4534 | ||
4535 | does not try to recursively expand the replacement text. | |
4536 | If the last character of the alias value is a | |
4537 | <I>blank</I>, | |
4538 | ||
4539 | then the next command | |
4540 | word following the alias is also checked for alias expansion. | |
4541 | <P> | |
4542 | ||
4543 | Aliases are created and listed with the | |
4544 | <B>alias</B> | |
4545 | ||
4546 | command, and removed with the | |
4547 | <B>unalias</B> | |
4548 | ||
4549 | command. | |
4550 | <P> | |
4551 | ||
4552 | There is no mechanism for using arguments in the replacement text. | |
4553 | If arguments are needed, a shell function should be used (see | |
4554 | <FONT SIZE=-1><B>FUNCTIONS</B> | |
4555 | ||
4556 | </FONT> | |
4557 | below). | |
4558 | <P> | |
4559 | ||
4560 | Aliases are not expanded when the shell is not interactive, unless | |
4561 | the | |
4562 | <B>expand_aliases</B> | |
4563 | ||
4564 | shell option is set using | |
4565 | <B>shopt</B> | |
4566 | ||
4567 | (see the description of | |
4568 | <B>shopt</B> | |
4569 | ||
4570 | under | |
4571 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B></FONT> | |
4572 | below). | |
4573 | <P> | |
4574 | ||
4575 | The rules concerning the definition and use of aliases are | |
4576 | somewhat confusing. | |
4577 | <B>Bash</B> | |
4578 | ||
4579 | always reads at least one complete line | |
4580 | of input before executing any | |
4581 | of the commands on that line. Aliases are expanded when a | |
4582 | command is read, not when it is executed. Therefore, an | |
4583 | alias definition appearing on the same line as another | |
4584 | command does not take effect until the next line of input is read. | |
4585 | The commands following the alias definition | |
4586 | on that line are not affected by the new alias. | |
4587 | This behavior is also an issue when functions are executed. | |
4588 | Aliases are expanded when a function definition is read, | |
4589 | not when the function is executed, because a function definition | |
4590 | is itself a compound command. As a consequence, aliases | |
4591 | defined in a function are not available until after that | |
4592 | function is executed. To be safe, always put | |
4593 | alias definitions on a separate line, and do not use | |
4594 | <B>alias</B> | |
4595 | ||
4596 | in compound commands. | |
4597 | <P> | |
4598 | ||
4599 | For almost every purpose, aliases are superseded by | |
4600 | shell functions. | |
4601 | <A NAME="lbBU"> </A> | |
4602 | <H3>FUNCTIONS</H3> | |
4603 | ||
4604 | A shell function, defined as described above under | |
4605 | <FONT SIZE=-1><B>SHELL GRAMMAR</B>, | |
4606 | ||
4607 | </FONT> | |
4608 | stores a series of commands for later execution. | |
4609 | When the name of a shell function is used as a simple command name, | |
4610 | the list of commands associated with that function name is executed. | |
4611 | Functions are executed in the context of the | |
4612 | current shell; no new process is created to interpret | |
4613 | them (contrast this with the execution of a shell script). | |
4614 | When a function is executed, the arguments to the | |
4615 | function become the positional parameters | |
4616 | during its execution. | |
4617 | The special parameter | |
4618 | <B>#</B> | |
4619 | ||
4620 | is updated to reflect the change. Special parameter 0 | |
4621 | is unchanged. | |
4622 | The first element of the | |
4623 | <FONT SIZE=-1><B>FUNCNAME</B> | |
4624 | ||
4625 | </FONT> | |
4626 | variable is set to the name of the function while the function | |
4627 | is executing. | |
4628 | All other aspects of the shell execution | |
4629 | environment are identical between a function and its caller | |
4630 | with the exception that the | |
4631 | <FONT SIZE=-1><B>DEBUG</B> | |
4632 | ||
4633 | </FONT> | |
4634 | and | |
4635 | <B>RETURN</B> | |
4636 | ||
4637 | traps (see the description of the | |
4638 | <B>trap</B> | |
4639 | ||
4640 | builtin under | |
4641 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
4642 | ||
4643 | </FONT> | |
4644 | below) are not inherited unless the function has been given the | |
4645 | <B>trace</B> attribute (see the description of the | |
4646 | <FONT SIZE=-1><B>declare</B> | |
4647 | ||
4648 | </FONT> | |
4649 | builtin below) or the | |
4650 | <B>-o functrace</B> shell option has been enabled with | |
4651 | the <B>set</B> builtin | |
4652 | (in which case all functions inherit the <B>DEBUG</B> and <B>RETURN</B> traps). | |
4653 | <P> | |
4654 | ||
4655 | Variables local to the function may be declared with the | |
4656 | <B>local</B> | |
4657 | ||
4658 | builtin command. Ordinarily, variables and their values | |
4659 | are shared between the function and its caller. | |
4660 | <P> | |
4661 | ||
4662 | If the builtin command | |
4663 | <B>return</B> | |
4664 | ||
4665 | is executed in a function, the function completes and | |
4666 | execution resumes with the next command after the function | |
4667 | call. | |
4668 | Any command associated with the <B>RETURN</B> trap is executed | |
4669 | before execution resumes. | |
4670 | When a function completes, the values of the | |
4671 | positional parameters and the special parameter | |
4672 | <B>#</B> | |
4673 | ||
4674 | are restored to the values they had prior to the function's | |
4675 | execution. | |
4676 | <P> | |
4677 | ||
4678 | Function names and definitions may be listed with the | |
4679 | <B>-f</B> | |
4680 | ||
4681 | option to the | |
4682 | <B>declare</B> | |
4683 | ||
4684 | or | |
4685 | <B>typeset</B> | |
4686 | ||
4687 | builtin commands. The | |
4688 | <B>-F</B> | |
4689 | ||
4690 | option to | |
4691 | <B>declare</B> | |
4692 | ||
4693 | or | |
4694 | <B>typeset</B> | |
4695 | ||
4696 | will list the function names only | |
4697 | (and optionally the source file and line number, if the <B>extdebug</B> | |
4698 | shell option is enabled). | |
4699 | Functions may be exported so that subshells | |
4700 | automatically have them defined with the | |
4701 | <B>-f</B> | |
4702 | ||
4703 | option to the | |
4704 | <B>export</B> | |
4705 | ||
4706 | builtin. | |
4707 | A function definition may be deleted using the <B>-f</B> option to | |
4708 | the | |
4709 | <B>unset</B> | |
4710 | ||
4711 | builtin. | |
4712 | Note that shell functions and variables with the same name may result | |
4713 | in multiple identically-named entries in the environment passed to the | |
4714 | shell's children. | |
4715 | Care should be taken in cases where this may cause a problem. | |
4716 | <P> | |
4717 | ||
4718 | Functions may be recursive. No limit is imposed on the number | |
4719 | of recursive calls. | |
4720 | <A NAME="lbBV"> </A> | |
4721 | <H3>ARITHMETIC EVALUATION</H3> | |
4722 | ||
4723 | The shell allows arithmetic expressions to be evaluated, under | |
4724 | certain circumstances (see the <B>let</B> and <B>declare</B> builtin | |
4725 | commands and <B>Arithmetic Expansion</B>). | |
4726 | Evaluation is done in fixed-width integers with no check for overflow, | |
4727 | though division by 0 is trapped and flagged as an error. | |
4728 | The operators and their precedence, associativity, and values | |
4729 | are the same as in the C language. | |
4730 | The following list of operators is grouped into levels of | |
4731 | equal-precedence operators. | |
4732 | The levels are listed in order of decreasing precedence. | |
4733 | <P> | |
4734 | ||
4735 | ||
4736 | <DL COMPACT> | |
4737 | <DT><B></B><I>id</I>++ <I>id</I>-- | |
4738 | ||
4739 | <DD> | |
4740 | variable post-increment and post-decrement | |
4741 | <DT><B>++</B><I>id</I> --<I>id</I> | |
4742 | ||
4743 | <DD> | |
4744 | variable pre-increment and pre-decrement | |
4745 | <DT><B>- +</B> | |
4746 | ||
4747 | <DD> | |
4748 | unary minus and plus | |
4749 | <DT><B>! ~</B> | |
4750 | ||
4751 | <DD> | |
4752 | logical and bitwise negation | |
4753 | <DT><B>**</B> | |
4754 | ||
4755 | <DD> | |
4756 | exponentiation | |
4757 | <DT><B>* / %</B> | |
4758 | ||
4759 | <DD> | |
4760 | multiplication, division, remainder | |
4761 | <DT><B>+ -</B> | |
4762 | ||
4763 | <DD> | |
4764 | addition, subtraction | |
4765 | <DT><B><< >></B> | |
4766 | ||
4767 | <DD> | |
4768 | left and right bitwise shifts | |
4769 | <DT><B><= >= < ></B> | |
4770 | ||
4771 | <DD> | |
4772 | comparison | |
4773 | <DT><B>== !=</B> | |
4774 | ||
4775 | <DD> | |
4776 | equality and inequality | |
4777 | <DT><B>&</B> | |
4778 | ||
4779 | <DD> | |
4780 | bitwise AND | |
4781 | <DT><B>^</B> | |
4782 | ||
4783 | <DD> | |
4784 | bitwise exclusive OR | |
4785 | <DT><B>|</B> | |
4786 | ||
4787 | <DD> | |
4788 | bitwise OR | |
4789 | <DT><B>&&</B> | |
4790 | ||
4791 | <DD> | |
4792 | logical AND | |
4793 | <DT><B>||</B> | |
4794 | ||
4795 | <DD> | |
4796 | logical OR | |
4797 | <DT><B></B><I>expr</I>?<I>expr</I>:<I>expr</I> | |
4798 | ||
4799 | <DD> | |
4800 | conditional operator | |
4801 | <DT><B>= *= /= %= += -= <<= >>= &= ^= |=</B> | |
4802 | ||
4803 | <DD> | |
4804 | assignment | |
4805 | <DT><B></B><I>expr1</I> , <I>expr2</I> | |
4806 | ||
4807 | <DD> | |
4808 | comma | |
4809 | ||
4810 | </DL> | |
4811 | <P> | |
4812 | ||
4813 | Shell variables are allowed as operands; parameter expansion is | |
4814 | performed before the expression is evaluated. | |
4815 | Within an expression, shell variables may also be referenced by name | |
4816 | without using the parameter expansion syntax. | |
4817 | A shell variable that is null or unset evaluates to 0 when referenced | |
4818 | by name without using the parameter expansion syntax. | |
4819 | The value of a variable is evaluated as an arithmetic expression | |
4820 | when it is referenced, or when a variable which has been given the | |
4821 | <I>integer</I> attribute using <B>declare -i</B> is assigned a value. | |
4822 | A null value evaluates to 0. | |
4823 | A shell variable need not have its integer attribute | |
4824 | turned on to be used in an expression. | |
4825 | <P> | |
4826 | ||
4827 | Constants with a leading 0 are interpreted as octal numbers. | |
4828 | A leading 0x or 0X denotes hexadecimal. | |
4829 | Otherwise, numbers take the form [<I>base#</I>]n, where <I>base</I> | |
4830 | is a decimal number between 2 and 64 representing the arithmetic | |
4831 | base, and <I>n</I> is a number in that base. | |
4832 | If <I>base#</I> is omitted, then base 10 is used. | |
4833 | The digits greater than 9 are represented by the lowercase letters, | |
4834 | the uppercase letters, @, and _, in that order. | |
4835 | If <I>base</I> is less than or equal to 36, lowercase and uppercase | |
4836 | letters may be used interchangeably to represent numbers between 10 | |
4837 | and 35. | |
4838 | <P> | |
4839 | ||
4840 | Operators are evaluated in order of precedence. Sub-expressions in | |
4841 | parentheses are evaluated first and may override the precedence | |
4842 | rules above. | |
4843 | <A NAME="lbBW"> </A> | |
4844 | <H3>CONDITIONAL EXPRESSIONS</H3> | |
4845 | ||
4846 | Conditional expressions are used by the <B>[[</B> compound command and | |
4847 | the <B>test</B> and <B>[</B> builtin commands to test file attributes | |
4848 | and perform string and arithmetic comparisons. | |
4849 | Expressions are formed from the following unary or binary primaries. | |
4850 | If any <I>file</I> argument to one of the primaries is of the form | |
4851 | <I>/dev/fd/n</I>, then file descriptor <I>n</I> is checked. | |
4852 | If the <I>file</I> argument to one of the primaries is one of | |
4853 | <I>/dev/stdin</I>, <I>/dev/stdout</I>, or <I>/dev/stderr</I>, file | |
4854 | descriptor 0, 1, or 2, respectively, is checked. | |
4855 | <P> | |
4856 | ||
4857 | Unless otherwise specified, primaries that operate on files follow symbolic | |
4858 | links and operate on the target of the link, rather than the link itself. | |
4859 | <P> | |
4860 | ||
4861 | <DL COMPACT> | |
4862 | <DT><B>-a </B><I>file</I> | |
4863 | ||
4864 | <DD> | |
4865 | True if <I>file</I> exists. | |
4866 | <DT><B>-b </B><I>file</I> | |
4867 | ||
4868 | <DD> | |
4869 | True if <I>file</I> exists and is a block special file. | |
4870 | <DT><B>-c </B><I>file</I> | |
4871 | ||
4872 | <DD> | |
4873 | True if <I>file</I> exists and is a character special file. | |
4874 | <DT><B>-d </B><I>file</I> | |
4875 | ||
4876 | <DD> | |
4877 | True if <I>file</I> exists and is a directory. | |
4878 | <DT><B>-e </B><I>file</I> | |
4879 | ||
4880 | <DD> | |
4881 | True if <I>file</I> exists. | |
4882 | <DT><B>-f </B><I>file</I> | |
4883 | ||
4884 | <DD> | |
4885 | True if <I>file</I> exists and is a regular file. | |
4886 | <DT><B>-g </B><I>file</I> | |
4887 | ||
4888 | <DD> | |
4889 | True if <I>file</I> exists and is set-group-id. | |
4890 | <DT><B>-h </B><I>file</I> | |
4891 | ||
4892 | <DD> | |
4893 | True if <I>file</I> exists and is a symbolic link. | |
4894 | <DT><B>-k </B><I>file</I> | |
4895 | ||
4896 | <DD> | |
4897 | True if <I>file</I> exists and its ``sticky'' bit is set. | |
4898 | <DT><B>-p </B><I>file</I> | |
4899 | ||
4900 | <DD> | |
4901 | True if <I>file</I> exists and is a named pipe (FIFO). | |
4902 | <DT><B>-r </B><I>file</I> | |
4903 | ||
4904 | <DD> | |
4905 | True if <I>file</I> exists and is readable. | |
4906 | <DT><B>-s </B><I>file</I> | |
4907 | ||
4908 | <DD> | |
4909 | True if <I>file</I> exists and has a size greater than zero. | |
4910 | <DT><B>-t </B><I>fd</I> | |
4911 | ||
4912 | <DD> | |
4913 | True if file descriptor | |
4914 | <I>fd</I> | |
4915 | ||
4916 | is open and refers to a terminal. | |
4917 | <DT><B>-u </B><I>file</I> | |
4918 | ||
4919 | <DD> | |
4920 | True if <I>file</I> exists and its set-user-id bit is set. | |
4921 | <DT><B>-w </B><I>file</I> | |
4922 | ||
4923 | <DD> | |
4924 | True if <I>file</I> exists and is writable. | |
4925 | <DT><B>-x </B><I>file</I> | |
4926 | ||
4927 | <DD> | |
4928 | True if <I>file</I> exists and is executable. | |
4929 | <DT><B>-O </B><I>file</I> | |
4930 | ||
4931 | <DD> | |
4932 | True if <I>file</I> exists and is owned by the effective user id. | |
4933 | <DT><B>-G </B><I>file</I> | |
4934 | ||
4935 | <DD> | |
4936 | True if <I>file</I> exists and is owned by the effective group id. | |
4937 | <DT><B>-L </B><I>file</I> | |
4938 | ||
4939 | <DD> | |
4940 | True if <I>file</I> exists and is a symbolic link. | |
4941 | <DT><B>-S </B><I>file</I> | |
4942 | ||
4943 | <DD> | |
4944 | True if <I>file</I> exists and is a socket. | |
4945 | <DT><B>-N </B><I>file</I> | |
4946 | ||
4947 | <DD> | |
4948 | True if <I>file</I> exists and has been modified since it was last read. | |
4949 | <DT><I>file1</I> -<B>nt</B> <I>file2</I><DD> | |
4950 | True if <I>file1</I> is newer (according to modification date) than <I>file2</I>, | |
4951 | or if <I>file1</I> exists and file2 does not. | |
4952 | <DT><I>file1</I> -<B>ot</B> <I>file2</I><DD> | |
4953 | True if <I>file1</I> is older than <I>file2</I>, or if <I>file2</I> exists | |
4954 | and <I>file1</I> does not. | |
4955 | <DT><I>file1</I> <B>-ef</B> <I>file2</I><DD> | |
4956 | True if <I>file1</I> and <I>file2</I> refer to the same device and | |
4957 | inode numbers. | |
4958 | <DT><B>-o </B><I>optname</I> | |
4959 | ||
4960 | <DD> | |
4961 | True if shell option | |
4962 | <I>optname</I> | |
4963 | ||
4964 | is enabled. | |
4965 | See the list of options under the description of the | |
4966 | <B>-o</B> | |
4967 | ||
4968 | option to the | |
4969 | <B>set</B> | |
4970 | ||
4971 | builtin below. | |
4972 | <DT><B>-z </B><I>string</I> | |
4973 | ||
4974 | <DD> | |
4975 | True if the length of <I>string</I> is zero. | |
4976 | <DT><I>string</I><DD> | |
4977 | ||
4978 | <DT><B>-n </B><I>string</I> | |
4979 | ||
4980 | <DD> | |
4981 | ||
4982 | True if the length of | |
4983 | <I>string</I> | |
4984 | ||
4985 | is non-zero. | |
4986 | <DT><I>string1</I> <B>==</B> <I>string2</I><DD> | |
4987 | True if the strings are equal. <B>=</B> may be used in place of | |
4988 | <B>==</B> for strict POSIX compliance. | |
4989 | <DT><I>string1</I> <B>!=</B> <I>string2</I><DD> | |
4990 | True if the strings are not equal. | |
4991 | <DT><I>string1</I> <B><</B> <I>string2</I><DD> | |
4992 | True if <I>string1</I> sorts before <I>string2</I> lexicographically | |
4993 | in the current locale. | |
4994 | <DT><I>string1</I> <B>></B> <I>string2</I><DD> | |
4995 | True if <I>string1</I> sorts after <I>string2</I> lexicographically | |
4996 | in the current locale. | |
4997 | <DT><I>arg1</I> <B>OP</B> <I>arg2</I> | |
4998 | ||
4999 | <DD> | |
5000 | <FONT SIZE=-1><B>OP</B> | |
5001 | ||
5002 | </FONT> | |
5003 | is one of | |
5004 | <B>-eq</B>, | |
5005 | ||
5006 | <B>-ne</B>, | |
5007 | ||
5008 | <B>-lt</B>, | |
5009 | ||
5010 | <B>-le</B>, | |
5011 | ||
5012 | <B>-gt</B>, | |
5013 | ||
5014 | or | |
5015 | <B>-ge</B>. | |
5016 | ||
5017 | These arithmetic binary operators return true if <I>arg1</I> | |
5018 | is equal to, not equal to, less than, less than or equal to, | |
5019 | greater than, or greater than or equal to <I>arg2</I>, respectively. | |
5020 | <I>Arg1</I> | |
5021 | ||
5022 | and | |
5023 | <I>arg2</I> | |
5024 | ||
5025 | may be positive or negative integers. | |
5026 | ||
5027 | </DL> | |
5028 | <A NAME="lbBX"> </A> | |
5029 | <H3>SIMPLE COMMAND EXPANSION</H3> | |
5030 | ||
5031 | When a simple command is executed, the shell performs the following | |
5032 | expansions, assignments, and redirections, from left to right. | |
5033 | <DL COMPACT> | |
5034 | <DT>1.<DD> | |
5035 | The words that the parser has marked as variable assignments (those | |
5036 | preceding the command name) and redirections are saved for later | |
5037 | processing. | |
5038 | <DT>2.<DD> | |
5039 | The words that are not variable assignments or redirections are | |
5040 | expanded. If any words remain after expansion, the first word | |
5041 | is taken to be the name of the command and the remaining words are | |
5042 | the arguments. | |
5043 | <DT>3.<DD> | |
5044 | Redirections are performed as described above under | |
5045 | <FONT SIZE=-1><B>REDIRECTION</B>. | |
5046 | ||
5047 | </FONT> | |
5048 | <DT>4.<DD> | |
5049 | The text after the <B>=</B> in each variable assignment undergoes tilde | |
5050 | expansion, parameter expansion, command substitution, arithmetic expansion, | |
5051 | and quote removal before being assigned to the variable. | |
5052 | </DL> | |
5053 | <P> | |
5054 | ||
5055 | If no command name results, the variable assignments affect the current | |
5056 | shell environment. Otherwise, the variables are added to the environment | |
5057 | of the executed command and do not affect the current shell environment. | |
5058 | If any of the assignments attempts to assign a value to a readonly variable, | |
5059 | an error occurs, and the command exits with a non-zero status. | |
5060 | <P> | |
5061 | ||
5062 | If no command name results, redirections are performed, but do not | |
5063 | affect the current shell environment. A redirection error causes the | |
5064 | command to exit with a non-zero status. | |
5065 | <P> | |
5066 | ||
5067 | If there is a command name left after expansion, execution proceeds as | |
5068 | described below. Otherwise, the command exits. If one of the expansions | |
5069 | contained a command substitution, the exit status of the command is | |
5070 | the exit status of the last command substitution performed. If there | |
5071 | were no command substitutions, the command exits with a status of zero. | |
5072 | <A NAME="lbBY"> </A> | |
5073 | <H3>COMMAND EXECUTION</H3> | |
5074 | ||
5075 | After a command has been split into words, if it results in a | |
5076 | simple command and an optional list of arguments, the following | |
5077 | actions are taken. | |
5078 | <P> | |
5079 | ||
5080 | If the command name contains no slashes, the shell attempts to | |
5081 | locate it. If there exists a shell function by that name, that | |
5082 | function is invoked as described above in | |
5083 | <FONT SIZE=-1><B>FUNCTIONS</B>. | |
5084 | ||
5085 | </FONT> | |
5086 | If the name does not match a function, the shell searches for | |
5087 | it in the list of shell builtins. If a match is found, that | |
5088 | builtin is invoked. | |
5089 | <P> | |
5090 | ||
5091 | If the name is neither a shell function nor a builtin, | |
5092 | and contains no slashes, | |
5093 | <B>bash</B> | |
5094 | ||
5095 | searches each element of the | |
5096 | <FONT SIZE=-1><B>PATH</B> | |
5097 | ||
5098 | </FONT> | |
5099 | for a directory containing an executable file by that name. | |
5100 | <B>Bash</B> | |
5101 | ||
5102 | uses a hash table to remember the full pathnames of executable | |
5103 | files (see | |
5104 | <B>hash</B> | |
5105 | ||
5106 | under | |
5107 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
5108 | ||
5109 | </FONT> | |
5110 | below). | |
5111 | A full search of the directories in | |
5112 | <FONT SIZE=-1><B>PATH</B> | |
5113 | ||
5114 | </FONT> | |
5115 | is performed only if the command is not found in the hash table. | |
5116 | If the search is unsuccessful, the shell searches for a defined shell | |
5117 | function named <B>command_not_found_handle</B>. | |
5118 | If that function exists, it is invoked with the original command and | |
5119 | the original command's arguments as its arguments, and the function's | |
5120 | exit status becomes the exit status of the shell. | |
5121 | If that function is not defined, the shell prints an error | |
5122 | message and returns an exit status of 127. | |
5123 | <P> | |
5124 | ||
5125 | If the search is successful, or if the command name contains | |
5126 | one or more slashes, the shell executes the named program in a | |
5127 | separate execution environment. | |
5128 | Argument 0 is set to the name given, and the remaining arguments | |
5129 | to the command are set to the arguments given, if any. | |
5130 | <P> | |
5131 | ||
5132 | If this execution fails because the file is not in executable | |
5133 | format, and the file is not a directory, it is assumed to be | |
5134 | a <I>shell script</I>, a file | |
5135 | containing shell commands. A subshell is spawned to execute | |
5136 | it. This subshell reinitializes itself, so | |
5137 | that the effect is as if a new shell had been invoked | |
5138 | to handle the script, with the exception that the locations of | |
5139 | commands remembered by the parent (see | |
5140 | <B>hash</B> | |
5141 | ||
5142 | below under | |
5143 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>)</FONT> | |
5144 | are retained by the child. | |
5145 | <P> | |
5146 | ||
5147 | If the program is a file beginning with | |
5148 | <B>#!</B>, | |
5149 | ||
5150 | the remainder of the first line specifies an interpreter | |
5151 | for the program. The shell executes the | |
5152 | specified interpreter on operating systems that do not | |
5153 | handle this executable format themselves. The arguments to the | |
5154 | interpreter consist of a single optional argument following the | |
5155 | interpreter name on the first line of the program, followed | |
5156 | by the name of the program, followed by the command | |
5157 | arguments, if any. | |
5158 | <A NAME="lbBZ"> </A> | |
5159 | <H3>COMMAND EXECUTION ENVIRONMENT</H3> | |
5160 | ||
5161 | The shell has an <I>execution environment</I>, which consists of the | |
5162 | following: | |
5163 | <P> | |
5164 | <DL COMPACT> | |
5165 | <DT>*<DD> | |
5166 | open files inherited by the shell at invocation, as modified by | |
5167 | redirections supplied to the <B>exec</B> builtin | |
5168 | <DT>*<DD> | |
5169 | the current working directory as set by <B>cd</B>, <B>pushd</B>, or | |
5170 | <B>popd</B>, or inherited by the shell at invocation | |
5171 | <DT>*<DD> | |
5172 | the file creation mode mask as set by <B>umask</B> or inherited from | |
5173 | the shell's parent | |
5174 | <DT>*<DD> | |
5175 | current traps set by <B>trap</B> | |
5176 | <DT>*<DD> | |
5177 | shell parameters that are set by variable assignment or with <B>set</B> | |
5178 | or inherited from the shell's parent in the environment | |
5179 | <DT>*<DD> | |
5180 | shell functions defined during execution or inherited from the shell's | |
5181 | parent in the environment | |
5182 | <DT>*<DD> | |
5183 | options enabled at invocation (either by default or with command-line | |
5184 | arguments) or by <B>set</B> | |
5185 | <DT>*<DD> | |
5186 | options enabled by <B>shopt</B> | |
5187 | <DT>*<DD> | |
5188 | shell aliases defined with <B>alias</B> | |
5189 | <DT>*<DD> | |
5190 | various process IDs, including those of background jobs, the value | |
5191 | of <B>$$</B>, and the value of <B>$PPID</B> | |
5192 | </DL> | |
5193 | <P> | |
5194 | ||
5195 | When a simple command other than a builtin or shell function | |
5196 | is to be executed, it | |
5197 | is invoked in a separate execution environment that consists of | |
5198 | the following. Unless otherwise noted, the values are inherited | |
5199 | from the shell. | |
5200 | <P> | |
5201 | <DL COMPACT> | |
5202 | <DT>*<DD> | |
5203 | the shell's open files, plus any modifications and additions specified | |
5204 | by redirections to the command | |
5205 | <DT>*<DD> | |
5206 | the current working directory | |
5207 | <DT>*<DD> | |
5208 | the file creation mode mask | |
5209 | <DT>*<DD> | |
5210 | shell variables and functions marked for export, along with variables | |
5211 | exported for the command, passed in the environment | |
5212 | <DT>*<DD> | |
5213 | traps caught by the shell are reset to the values inherited from the | |
5214 | shell's parent, and traps ignored by the shell are ignored | |
5215 | </DL> | |
5216 | <P> | |
5217 | ||
5218 | A command invoked in this separate environment cannot affect the | |
5219 | shell's execution environment. | |
5220 | <P> | |
5221 | ||
5222 | Command substitution, commands grouped with parentheses, | |
5223 | and asynchronous commands are invoked in a | |
5224 | subshell environment that is a duplicate of the shell environment, | |
5225 | except that traps caught by the shell are reset to the values | |
5226 | that the shell inherited from its parent at invocation. Builtin | |
5227 | commands that are invoked as part of a pipeline are also executed in a | |
5228 | subshell environment. Changes made to the subshell environment | |
5229 | cannot affect the shell's execution environment. | |
5230 | <P> | |
5231 | ||
5232 | Subshells spawned to execute command substitutions inherit the value of | |
5233 | the <B>-e</B> option from the parent shell. When not in posix mode, | |
5234 | Bash clears the <B>-e</B> option in such subshells. | |
5235 | <P> | |
5236 | ||
5237 | If a command is followed by a <B>&</B> and job control is not active, the | |
5238 | default standard input for the command is the empty file <I>/dev/null</I>. | |
5239 | Otherwise, the invoked command inherits the file descriptors of the calling | |
5240 | shell as modified by redirections. | |
5241 | <A NAME="lbCA"> </A> | |
5242 | <H3>ENVIRONMENT</H3> | |
5243 | ||
5244 | When a program is invoked it is given an array of strings | |
5245 | called the | |
5246 | <I>environment</I>. | |
5247 | ||
5248 | This is a list of | |
5249 | <I>name</I>-<I>value</I> pairs, of the form | |
5250 | <I>name</I>=value. | |
5251 | ||
5252 | <P> | |
5253 | ||
5254 | The shell provides several ways to manipulate the environment. | |
5255 | On invocation, the shell scans its own environment and | |
5256 | creates a parameter for each name found, automatically marking | |
5257 | it for | |
5258 | <I>export</I> | |
5259 | ||
5260 | to child processes. Executed commands inherit the environment. | |
5261 | The | |
5262 | <B>export</B> | |
5263 | ||
5264 | and | |
5265 | <B>declare -x</B> | |
5266 | ||
5267 | commands allow parameters and functions to be added to and | |
5268 | deleted from the environment. If the value of a parameter | |
5269 | in the environment is modified, the new value becomes part | |
5270 | of the environment, replacing the old. The environment | |
5271 | inherited by any executed command consists of the shell's | |
5272 | initial environment, whose values may be modified in the shell, | |
5273 | less any pairs removed by the | |
5274 | <B>unset</B> | |
5275 | ||
5276 | command, plus any additions via the | |
5277 | <B>export</B> | |
5278 | ||
5279 | and | |
5280 | <B>declare -x</B> | |
5281 | ||
5282 | commands. | |
5283 | <P> | |
5284 | ||
5285 | The environment for any | |
5286 | <I>simple command</I> | |
5287 | ||
5288 | or function may be augmented temporarily by prefixing it with | |
5289 | parameter assignments, as described above in | |
5290 | <FONT SIZE=-1><B>PARAMETERS</B>. | |
5291 | ||
5292 | </FONT> | |
5293 | These assignment statements affect only the environment seen | |
5294 | by that command. | |
5295 | <P> | |
5296 | ||
5297 | If the | |
5298 | <B>-k</B> | |
5299 | ||
5300 | option is set (see the | |
5301 | <B>set</B> | |
5302 | ||
5303 | builtin command below), then | |
5304 | <I>all</I> | |
5305 | ||
5306 | parameter assignments are placed in the environment for a command, | |
5307 | not just those that precede the command name. | |
5308 | <P> | |
5309 | ||
5310 | When | |
5311 | <B>bash</B> | |
5312 | ||
5313 | invokes an external command, the variable | |
5314 | <B>_</B> | |
5315 | ||
5316 | is set to the full file name of the command and passed to that | |
5317 | command in its environment. | |
5318 | <A NAME="lbCB"> </A> | |
5319 | <H3>EXIT STATUS</H3> | |
5320 | ||
5321 | <P> | |
5322 | ||
5323 | The exit status of an executed command is the value returned by the | |
5324 | <I>waitpid</I> system call or equivalent function. Exit statuses | |
5325 | fall between 0 and 255, though, as explained below, the shell may | |
5326 | use values above 125 specially. Exit statuses from shell builtins and | |
5327 | compound commands are also limited to this range. Under certain | |
5328 | circumstances, the shell will use special values to indicate specific | |
5329 | failure modes. | |
5330 | <P> | |
5331 | ||
5332 | For the shell's purposes, a command which exits with a | |
5333 | zero exit status has succeeded. An exit status of zero | |
5334 | indicates success. A non-zero exit status indicates failure. | |
5335 | When a command terminates on a fatal signal <I>N</I>, <B>bash</B> uses | |
5336 | the value of 128+<I>N</I> as the exit status. | |
5337 | <P> | |
5338 | ||
5339 | If a command is not found, the child process created to | |
5340 | execute it returns a status of 127. If a command is found | |
5341 | but is not executable, the return status is 126. | |
5342 | <P> | |
5343 | ||
5344 | If a command fails because of an error during expansion or redirection, | |
5345 | the exit status is greater than zero. | |
5346 | <P> | |
5347 | ||
5348 | Shell builtin commands return a status of 0 (<I>true</I>) if | |
5349 | successful, and non-zero (<I>false</I>) if an error occurs | |
5350 | while they execute. | |
5351 | All builtins return an exit status of 2 to indicate incorrect usage. | |
5352 | <P> | |
5353 | ||
5354 | <B>Bash</B> itself returns the exit status of the last command | |
5355 | executed, unless a syntax error occurs, in which case it exits | |
5356 | with a non-zero value. See also the <B>exit</B> builtin | |
5357 | command below. | |
5358 | <A NAME="lbCC"> </A> | |
5359 | <H3>SIGNALS</H3> | |
5360 | ||
5361 | When <B>bash</B> is interactive, in the absence of any traps, it ignores | |
5362 | <FONT SIZE=-1><B>SIGTERM</B> | |
5363 | ||
5364 | </FONT> | |
5365 | (so that <B>kill 0</B> does not kill an interactive shell), | |
5366 | and | |
5367 | <FONT SIZE=-1><B>SIGINT</B> | |
5368 | ||
5369 | </FONT> | |
5370 | is caught and handled (so that the <B>wait</B> builtin is interruptible). | |
5371 | In all cases, <B>bash</B> ignores | |
5372 | <FONT SIZE=-1><B>SIGQUIT</B>. | |
5373 | ||
5374 | </FONT> | |
5375 | If job control is in effect, | |
5376 | <B>bash</B> | |
5377 | ||
5378 | ignores | |
5379 | <FONT SIZE=-1><B>SIGTTIN</B>, | |
5380 | ||
5381 | </FONT> | |
5382 | <FONT SIZE=-1><B>SIGTTOU</B>, | |
5383 | ||
5384 | </FONT> | |
5385 | and | |
5386 | <FONT SIZE=-1><B>SIGTSTP</B>. | |
5387 | ||
5388 | </FONT> | |
5389 | <P> | |
5390 | ||
5391 | Non-builtin commands run by <B>bash</B> have signal handlers | |
5392 | set to the values inherited by the shell from its parent. | |
5393 | When job control is not in effect, asynchronous commands | |
5394 | ignore | |
5395 | <FONT SIZE=-1><B>SIGINT</B> | |
5396 | ||
5397 | </FONT> | |
5398 | and | |
5399 | <FONT SIZE=-1><B>SIGQUIT</B> | |
5400 | ||
5401 | </FONT> | |
5402 | in addition to these inherited handlers. | |
5403 | Commands run as a result of command substitution ignore the | |
5404 | keyboard-generated job control signals | |
5405 | <FONT SIZE=-1><B>SIGTTIN</B>, | |
5406 | ||
5407 | </FONT> | |
5408 | <FONT SIZE=-1><B>SIGTTOU</B>, | |
5409 | ||
5410 | </FONT> | |
5411 | and | |
5412 | <FONT SIZE=-1><B>SIGTSTP</B>. | |
5413 | ||
5414 | </FONT> | |
5415 | <P> | |
5416 | ||
5417 | The shell exits by default upon receipt of a | |
5418 | <FONT SIZE=-1><B>SIGHUP</B>. | |
5419 | ||
5420 | </FONT> | |
5421 | Before exiting, an interactive shell resends the | |
5422 | <FONT SIZE=-1><B>SIGHUP</B> | |
5423 | ||
5424 | </FONT> | |
5425 | to all jobs, running or stopped. | |
5426 | Stopped jobs are sent | |
5427 | <FONT SIZE=-1><B>SIGCONT</B> | |
5428 | ||
5429 | </FONT> | |
5430 | to ensure that they receive the | |
5431 | <FONT SIZE=-1><B>SIGHUP</B>. | |
5432 | ||
5433 | </FONT> | |
5434 | To prevent the shell from | |
5435 | sending the signal to a particular job, it should be removed from the | |
5436 | jobs table with the | |
5437 | <B>disown</B> | |
5438 | ||
5439 | builtin (see | |
5440 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
5441 | ||
5442 | </FONT> | |
5443 | below) or marked | |
5444 | to not receive | |
5445 | <FONT SIZE=-1><B>SIGHUP</B> | |
5446 | ||
5447 | </FONT> | |
5448 | using | |
5449 | <B>disown -h</B>. | |
5450 | ||
5451 | <P> | |
5452 | ||
5453 | If the | |
5454 | <B>huponexit</B> | |
5455 | ||
5456 | shell option has been set with | |
5457 | <B>shopt</B>, | |
5458 | ||
5459 | <B>bash</B> | |
5460 | ||
5461 | sends a | |
5462 | <FONT SIZE=-1><B>SIGHUP</B> | |
5463 | ||
5464 | </FONT> | |
5465 | to all jobs when an interactive login shell exits. | |
5466 | <P> | |
5467 | ||
5468 | If <B>bash</B> is waiting for a command to complete and receives a signal | |
5469 | for which a trap has been set, the trap will not be executed until | |
5470 | the command completes. | |
5471 | When <B>bash</B> is waiting for an asynchronous command via the <B>wait</B> | |
5472 | builtin, the reception of a signal for which a trap has been set will | |
5473 | cause the <B>wait</B> builtin to return immediately with an exit status | |
5474 | greater than 128, immediately after which the trap is executed. | |
5475 | <A NAME="lbCD"> </A> | |
5476 | <H3>JOB CONTROL</H3> | |
5477 | ||
5478 | <I>Job control</I> | |
5479 | ||
5480 | refers to the ability to selectively stop (<I>suspend</I>) | |
5481 | the execution of processes and continue (<I>resume</I>) | |
5482 | their execution at a later point. A user typically employs | |
5483 | this facility via an interactive interface supplied jointly | |
5484 | by the system's terminal driver and | |
5485 | <B>bash</B>. | |
5486 | ||
5487 | <P> | |
5488 | ||
5489 | The shell associates a | |
5490 | <I>job</I> | |
5491 | ||
5492 | with each pipeline. It keeps a table of currently executing | |
5493 | jobs, which may be listed with the | |
5494 | <B>jobs</B> | |
5495 | ||
5496 | command. When | |
5497 | <B>bash</B> | |
5498 | ||
5499 | starts a job asynchronously (in the | |
5500 | <I>background</I>), | |
5501 | ||
5502 | it prints a line that looks like: | |
5503 | <DL COMPACT><DT><DD> | |
5504 | <P> | |
5505 | ||
5506 | [1] 25647 | |
5507 | </DL> | |
5508 | ||
5509 | <P> | |
5510 | ||
5511 | indicating that this job is job number 1 and that the process ID | |
5512 | of the last process in the pipeline associated with this job is 25647. | |
5513 | All of the processes in a single pipeline are members of the same job. | |
5514 | <B>Bash</B> | |
5515 | ||
5516 | uses the | |
5517 | <I>job</I> | |
5518 | ||
5519 | abstraction as the basis for job control. | |
5520 | <P> | |
5521 | ||
5522 | To facilitate the implementation of the user interface to job | |
5523 | control, the operating system maintains the notion of a <I>current terminal | |
5524 | process group ID</I>. Members of this process group (processes whose | |
5525 | process group ID is equal to the current terminal process group ID) | |
5526 | receive keyboard-generated signals such as | |
5527 | <FONT SIZE=-1><B>SIGINT</B>. | |
5528 | ||
5529 | </FONT> | |
5530 | These processes are said to be in the | |
5531 | <I>foreground</I>. | |
5532 | ||
5533 | <I>Background</I> | |
5534 | ||
5535 | processes are those whose process group ID differs from the terminal's; | |
5536 | such processes are immune to keyboard-generated signals. | |
5537 | Only foreground processes are allowed to read from or write to the | |
5538 | terminal. Background processes which attempt to read from (write to) the | |
5539 | terminal are sent a | |
5540 | <FONT SIZE=-1><B>SIGTTIN (SIGTTOU)</B> | |
5541 | ||
5542 | </FONT> | |
5543 | signal by the terminal driver, | |
5544 | which, unless caught, suspends the process. | |
5545 | <P> | |
5546 | ||
5547 | If the operating system on which | |
5548 | <B>bash</B> | |
5549 | ||
5550 | is running supports | |
5551 | job control, | |
5552 | <B>bash</B> | |
5553 | ||
5554 | contains facilities to use it. | |
5555 | Typing the | |
5556 | <I>suspend</I> | |
5557 | ||
5558 | character (typically | |
5559 | <B>^Z</B>, | |
5560 | ||
5561 | Control-Z) while a process is running | |
5562 | causes that process to be stopped and returns control to | |
5563 | <B>bash</B>. | |
5564 | ||
5565 | Typing the | |
5566 | <I>delayed suspend</I> | |
5567 | ||
5568 | character (typically | |
5569 | <B>^Y</B>, | |
5570 | ||
5571 | Control-Y) causes the process to be stopped when it | |
5572 | attempts to read input from the terminal, and control to | |
5573 | be returned to | |
5574 | <B>bash</B>. | |
5575 | ||
5576 | The user may then manipulate the state of this job, using the | |
5577 | <B>bg</B> | |
5578 | ||
5579 | command to continue it in the background, the | |
5580 | <B>fg</B> | |
5581 | ||
5582 | command to continue it in the foreground, or | |
5583 | the | |
5584 | <B>kill</B> | |
5585 | ||
5586 | command to kill it. A <B>^Z</B> takes effect immediately, | |
5587 | and has the additional side effect of causing pending output | |
5588 | and typeahead to be discarded. | |
5589 | <P> | |
5590 | ||
5591 | There are a number of ways to refer to a job in the shell. | |
5592 | The character | |
5593 | <B>%</B> | |
5594 | ||
5595 | introduces a job specification (<I>jobspec</I>). Job number | |
5596 | <I>n</I> | |
5597 | ||
5598 | may be referred to as | |
5599 | <B>%n</B>. | |
5600 | ||
5601 | A job may also be referred to using a prefix of the name used to | |
5602 | start it, or using a substring that appears in its command line. | |
5603 | For example, | |
5604 | <B>%ce</B> | |
5605 | ||
5606 | refers to a stopped | |
5607 | <B>ce</B> | |
5608 | ||
5609 | job. If a prefix matches more than one job, | |
5610 | <B>bash</B> | |
5611 | ||
5612 | reports an error. Using | |
5613 | <B>%?ce</B>, | |
5614 | ||
5615 | on the other hand, refers to any job containing the string | |
5616 | <B>ce</B> | |
5617 | ||
5618 | in its command line. If the substring matches more than one job, | |
5619 | <B>bash</B> | |
5620 | ||
5621 | reports an error. The symbols | |
5622 | <B>%%</B> | |
5623 | ||
5624 | and | |
5625 | <B>%+</B> | |
5626 | ||
5627 | refer to the shell's notion of the | |
5628 | <I>current job</I>, | |
5629 | ||
5630 | which is the last job stopped while it was in | |
5631 | the foreground or started in the background. | |
5632 | The | |
5633 | <I>previous job</I> | |
5634 | ||
5635 | may be referenced using | |
5636 | <B>%-</B>. | |
5637 | ||
5638 | If there is only a single job, <B>%+</B> and <B>%-</B> can both be used | |
5639 | to refer to that job. | |
5640 | In output pertaining to jobs (e.g., the output of the | |
5641 | <B>jobs</B> | |
5642 | ||
5643 | command), the current job is always flagged with a | |
5644 | <B>+</B>, | |
5645 | ||
5646 | and the previous job with a | |
5647 | <B>-</B>. | |
5648 | ||
5649 | A single % (with no accompanying job specification) also refers to the | |
5650 | current job. | |
5651 | <P> | |
5652 | ||
5653 | Simply naming a job can be used to bring it into the | |
5654 | foreground: | |
5655 | <B>%1</B> | |
5656 | ||
5657 | is a synonym for | |
5658 | <B>``fg %1''</B>, | |
5659 | bringing job 1 from the background into the foreground. | |
5660 | Similarly, | |
5661 | <B>``%1 &''</B> | |
5662 | ||
5663 | resumes job 1 in the background, equivalent to | |
5664 | <B>``bg %1''</B>. | |
5665 | <P> | |
5666 | ||
5667 | The shell learns immediately whenever a job changes state. | |
5668 | Normally, | |
5669 | <B>bash</B> | |
5670 | ||
5671 | waits until it is about to print a prompt before reporting | |
5672 | changes in a job's status so as to not interrupt | |
5673 | any other output. If the | |
5674 | <B>-b</B> | |
5675 | ||
5676 | option to the | |
5677 | <B>set</B> | |
5678 | ||
5679 | builtin command | |
5680 | is enabled, | |
5681 | <B>bash</B> | |
5682 | ||
5683 | reports such changes immediately. | |
5684 | Any trap on | |
5685 | <FONT SIZE=-1><B>SIGCHLD</B> | |
5686 | ||
5687 | </FONT> | |
5688 | is executed for each child that exits. | |
5689 | <P> | |
5690 | ||
5691 | If an attempt to exit | |
5692 | <B>bash</B> | |
5693 | ||
5694 | is made while jobs are stopped (or, if the <B>checkjobs</B> shell option has | |
5695 | been enabled using the <B>shopt</B> builtin, running), the shell prints a | |
5696 | warning message, and, if the <B>checkjobs</B> option is enabled, lists the | |
5697 | jobs and their statuses. | |
5698 | The | |
5699 | <B>jobs</B> | |
5700 | ||
5701 | command may then be used to inspect their status. | |
5702 | If a second attempt to exit is made without an intervening command, | |
5703 | the shell does not print another warning, and any stopped | |
5704 | jobs are terminated. | |
5705 | <A NAME="lbCE"> </A> | |
5706 | <H3>PROMPTING</H3> | |
5707 | ||
5708 | When executing interactively, | |
5709 | <B>bash</B> | |
5710 | ||
5711 | displays the primary prompt | |
5712 | <FONT SIZE=-1><B>PS1</B> | |
5713 | ||
5714 | </FONT> | |
5715 | when it is ready to read a command, and the secondary prompt | |
5716 | <FONT SIZE=-1><B>PS2</B> | |
5717 | ||
5718 | </FONT> | |
5719 | when it needs more input to complete a command. | |
5720 | <B>Bash</B> | |
5721 | ||
5722 | allows these prompt strings to be customized by inserting a number of | |
5723 | backslash-escaped special characters that are decoded as follows: | |
5724 | <DL COMPACT><DT><DD> | |
5725 | ||
5726 | <DL COMPACT> | |
5727 | <DT><B>\a</B> | |
5728 | ||
5729 | <DD> | |
5730 | an ASCII bell character (07) | |
5731 | <DT><B>\d</B> | |
5732 | ||
5733 | <DD> | |
5734 | the date in "Weekday Month Date" format (e.g., "Tue May 26") | |
5735 | <DT><B>\D{</B><I>format</I>} | |
5736 | ||
5737 | <DD> | |
5738 | the <I>format</I> is passed to <I>strftime</I>(3) and the result is inserted | |
5739 | into the prompt string; an empty <I>format</I> results in a locale-specific | |
5740 | time representation. The braces are required | |
5741 | <DT><B>\e</B> | |
5742 | ||
5743 | <DD> | |
5744 | an ASCII escape character (033) | |
5745 | <DT><B>\h</B> | |
5746 | ||
5747 | <DD> | |
5748 | the hostname up to the first `.' | |
5749 | <DT><B>\H</B> | |
5750 | ||
5751 | <DD> | |
5752 | the hostname | |
5753 | <DT><B>\j</B> | |
5754 | ||
5755 | <DD> | |
5756 | the number of jobs currently managed by the shell | |
5757 | <DT><B>\l</B> | |
5758 | ||
5759 | <DD> | |
5760 | the basename of the shell's terminal device name | |
5761 | <DT><B>\n</B> | |
5762 | ||
5763 | <DD> | |
5764 | newline | |
5765 | <DT><B>\r</B> | |
5766 | ||
5767 | <DD> | |
5768 | carriage return | |
5769 | <DT><B>\s</B> | |
5770 | ||
5771 | <DD> | |
5772 | the name of the shell, the basename of | |
5773 | <B>$0</B> | |
5774 | ||
5775 | (the portion following the final slash) | |
5776 | <DT><B>\t</B> | |
5777 | ||
5778 | <DD> | |
5779 | the current time in 24-hour HH:MM:SS format | |
5780 | <DT><B>\T</B> | |
5781 | ||
5782 | <DD> | |
5783 | the current time in 12-hour HH:MM:SS format | |
5784 | <DT><B>\@</B> | |
5785 | ||
5786 | <DD> | |
5787 | the current time in 12-hour am/pm format | |
5788 | <DT><B>\A</B> | |
5789 | ||
5790 | <DD> | |
5791 | the current time in 24-hour HH:MM format | |
5792 | <DT><B>\u</B> | |
5793 | ||
5794 | <DD> | |
5795 | the username of the current user | |
5796 | <DT><B>\v</B> | |
5797 | ||
5798 | <DD> | |
5799 | the version of <B>bash</B> (e.g., 2.00) | |
5800 | <DT><B>\V</B> | |
5801 | ||
5802 | <DD> | |
5803 | the release of <B>bash</B>, version + patch level (e.g., 2.00.0) | |
5804 | <DT><B>\w</B> | |
5805 | ||
5806 | <DD> | |
5807 | the current working directory, with <B>$HOME</B> abbreviated with a tilde | |
5808 | (uses the <B>$PROMPT_DIRTRIM</B> variable) | |
5809 | <DT><B>\W</B> | |
5810 | ||
5811 | <DD> | |
5812 | the basename of the current working directory, with <B>$HOME</B> | |
5813 | abbreviated with a tilde | |
5814 | <DT><B>\!</B> | |
5815 | ||
5816 | <DD> | |
5817 | the history number of this command | |
5818 | <DT><B>\#</B> | |
5819 | ||
5820 | <DD> | |
5821 | the command number of this command | |
5822 | <DT><B>\$</B> | |
5823 | ||
5824 | <DD> | |
5825 | if the effective UID is 0, a | |
5826 | <B>#</B>, | |
5827 | ||
5828 | otherwise a | |
5829 | <B>$</B> | |
5830 | ||
5831 | <DT><B>\</B><I>nnn</I> | |
5832 | ||
5833 | <DD> | |
5834 | the character corresponding to the octal number <I>nnn</I> | |
5835 | <DT><B>\\</B> | |
5836 | ||
5837 | <DD> | |
5838 | a backslash | |
5839 | <DT><B>\[</B> | |
5840 | ||
5841 | <DD> | |
5842 | begin a sequence of non-printing characters, which could be used to | |
5843 | embed a terminal control sequence into the prompt | |
5844 | <DT><B>\]</B> | |
5845 | ||
5846 | <DD> | |
5847 | end a sequence of non-printing characters | |
5848 | ||
5849 | </DL></DL> | |
5850 | ||
5851 | <P> | |
5852 | ||
5853 | The command number and the history number are usually different: | |
5854 | the history number of a command is its position in the history | |
5855 | list, which may include commands restored from the history file | |
5856 | (see | |
5857 | <FONT SIZE=-1><B>HISTORY</B> | |
5858 | ||
5859 | </FONT> | |
5860 | below), while the command number is the position in the sequence | |
5861 | of commands executed during the current shell session. | |
5862 | After the string is decoded, it is expanded via | |
5863 | parameter expansion, command substitution, arithmetic | |
5864 | expansion, and quote removal, subject to the value of the | |
5865 | <B>promptvars</B> | |
5866 | ||
5867 | shell option (see the description of the | |
5868 | <B>shopt</B> | |
5869 | ||
5870 | command under | |
5871 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
5872 | ||
5873 | </FONT> | |
5874 | below). | |
5875 | <A NAME="lbCF"> </A> | |
5876 | <H3>READLINE</H3> | |
5877 | ||
5878 | This is the library that handles reading input when using an interactive | |
5879 | shell, unless the | |
5880 | <B>--noediting</B> | |
5881 | ||
5882 | option is given at shell invocation. | |
5883 | Line editing is also used when using the <B>-e</B> option to the | |
5884 | <B>read</B> builtin. | |
5885 | By default, the line editing commands are similar to those of emacs. | |
5886 | A vi-style line editing interface is also available. | |
5887 | Line editing can be enabled at any time using the | |
5888 | <B>-o emacs</B> | |
5889 | ||
5890 | or | |
5891 | <B>-o vi</B> | |
5892 | ||
5893 | options to the | |
5894 | <B>set</B> | |
5895 | ||
5896 | builtin (see | |
5897 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
5898 | ||
5899 | </FONT> | |
5900 | below). | |
5901 | To turn off line editing after the shell is running, use the | |
5902 | <B>+o emacs</B> | |
5903 | ||
5904 | or | |
5905 | <B>+o vi</B> | |
5906 | ||
5907 | options to the | |
5908 | <B>set</B> | |
5909 | ||
5910 | builtin. | |
5911 | <A NAME="lbCG"> </A> | |
5912 | <H4>Readline Notation</H4> | |
5913 | ||
5914 | <P> | |
5915 | ||
5916 | In this section, the emacs-style notation is used to denote | |
5917 | keystrokes. Control keys are denoted by C-<I>key</I>, e.g., C-n | |
5918 | means Control-N. Similarly, | |
5919 | <I>meta</I> | |
5920 | ||
5921 | keys are denoted by M-<I>key</I>, so M-x means Meta-X. (On keyboards | |
5922 | without a | |
5923 | <I>meta</I> | |
5924 | ||
5925 | key, M-<I>x</I> means ESC <I>x</I>, i.e., press the Escape key | |
5926 | then the | |
5927 | <I>x</I> | |
5928 | ||
5929 | key. This makes ESC the <I>meta prefix</I>. | |
5930 | The combination M-C-<I>x</I> means ESC-Control-<I>x</I>, | |
5931 | or press the Escape key | |
5932 | then hold the Control key while pressing the | |
5933 | <I>x</I> | |
5934 | ||
5935 | key.) | |
5936 | <P> | |
5937 | ||
5938 | Readline commands may be given numeric | |
5939 | <I>arguments</I>, | |
5940 | ||
5941 | which normally act as a repeat count. | |
5942 | Sometimes, however, it is the sign of the argument that is significant. | |
5943 | Passing a negative argument to a command that acts in the forward | |
5944 | direction (e.g., <B>kill-line</B>) causes that command to act in a | |
5945 | backward direction. | |
5946 | Commands whose behavior with arguments deviates from this are noted | |
5947 | below. | |
5948 | <P> | |
5949 | ||
5950 | When a command is described as <I>killing</I> text, the text | |
5951 | deleted is saved for possible future retrieval | |
5952 | (<I>yanking</I>). The killed text is saved in a | |
5953 | <I>kill ring</I>. Consecutive kills cause the text to be | |
5954 | accumulated into one unit, which can be yanked all at once. | |
5955 | Commands which do not kill text separate the chunks of text | |
5956 | on the kill ring. | |
5957 | <A NAME="lbCH"> </A> | |
5958 | <H4>Readline Initialization</H4> | |
5959 | ||
5960 | <P> | |
5961 | ||
5962 | Readline is customized by putting commands in an initialization | |
5963 | file (the <I>inputrc</I> file). | |
5964 | The name of this file is taken from the value of the | |
5965 | <FONT SIZE=-1><B>INPUTRC</B> | |
5966 | ||
5967 | </FONT> | |
5968 | variable. If that variable is unset, the default is | |
5969 | <A HREF="file:~/.inputrc"><I>~/.inputrc</I></A>. | |
5970 | ||
5971 | When a program which uses the readline library starts up, the | |
5972 | initialization file is read, and the key bindings and variables | |
5973 | are set. | |
5974 | There are only a few basic constructs allowed in the | |
5975 | readline initialization file. | |
5976 | Blank lines are ignored. | |
5977 | Lines beginning with a <B>#</B> are comments. | |
5978 | Lines beginning with a <B>$</B> indicate conditional constructs. | |
5979 | Other lines denote key bindings and variable settings. | |
5980 | <P> | |
5981 | ||
5982 | The default key-bindings may be changed with an | |
5983 | <I>inputrc </I> | |
5984 | ||
5985 | file. | |
5986 | Other programs that use this library may add their own commands | |
5987 | and bindings. | |
5988 | <P> | |
5989 | ||
5990 | For example, placing | |
5991 | <DL COMPACT><DT><DD> | |
5992 | <P> | |
5993 | ||
5994 | M-Control-u: universal-argument | |
5995 | </DL> | |
5996 | ||
5997 | or | |
5998 | <DL COMPACT><DT><DD> | |
5999 | C-Meta-u: universal-argument | |
6000 | </DL> | |
6001 | ||
6002 | into the | |
6003 | <I>inputrc</I> | |
6004 | ||
6005 | would make M-C-u execute the readline command | |
6006 | <I>universal-argument</I>. | |
6007 | ||
6008 | <P> | |
6009 | ||
6010 | The following symbolic character names are recognized: | |
6011 | <I>RUBOUT</I>, | |
6012 | ||
6013 | <I>DEL</I>, | |
6014 | ||
6015 | <I>ESC</I>, | |
6016 | ||
6017 | <I>LFD</I>, | |
6018 | ||
6019 | <I>NEWLINE</I>, | |
6020 | ||
6021 | <I>RET</I>, | |
6022 | ||
6023 | <I>RETURN</I>, | |
6024 | ||
6025 | <I>SPC</I>, | |
6026 | ||
6027 | <I>SPACE</I>, | |
6028 | ||
6029 | and | |
6030 | <I>TAB</I>. | |
6031 | ||
6032 | <P> | |
6033 | ||
6034 | In addition to command names, readline allows keys to be bound | |
6035 | to a string that is inserted when the key is pressed (a <I>macro</I>). | |
6036 | <A NAME="lbCI"> </A> | |
6037 | <H4>Readline Key Bindings</H4> | |
6038 | ||
6039 | <P> | |
6040 | ||
6041 | The syntax for controlling key bindings in the | |
6042 | <I>inputrc</I> | |
6043 | ||
6044 | file is simple. All that is required is the name of the | |
6045 | command or the text of a macro and a key sequence to which | |
6046 | it should be bound. The name may be specified in one of two ways: | |
6047 | as a symbolic key name, possibly with <I>Meta-</I> or <I>Control-</I> | |
6048 | prefixes, or as a key sequence. | |
6049 | <P> | |
6050 | ||
6051 | When using the form <B>keyname</B>:<I>function-name</I> or <I>macro</I>, | |
6052 | <I>keyname</I> | |
6053 | ||
6054 | is the name of a key spelled out in English. For example: | |
6055 | <P> | |
6056 | <DL COMPACT><DT><DD> | |
6057 | Control-u: universal-argument | |
6058 | <BR> | |
6059 | ||
6060 | Meta-Rubout: backward-kill-word | |
6061 | <BR> | |
6062 | ||
6063 | Control-o: "> output" | |
6064 | </DL> | |
6065 | ||
6066 | <P> | |
6067 | ||
6068 | In the above example, | |
6069 | <I>C-u</I> | |
6070 | ||
6071 | is bound to the function | |
6072 | <B>universal-argument</B>, | |
6073 | ||
6074 | <I>M-DEL</I> | |
6075 | ||
6076 | is bound to the function | |
6077 | <B>backward-kill-word</B>, | |
6078 | ||
6079 | and | |
6080 | <I>C-o</I> | |
6081 | ||
6082 | is bound to run the macro | |
6083 | expressed on the right hand side (that is, to insert the text | |
6084 | <TT>> output</TT> | |
6085 | ||
6086 | into the line). | |
6087 | <P> | |
6088 | ||
6089 | In the second form, <B>"keyseq"</B>:<I>function-name</I> or <I>macro</I>, | |
6090 | <B>keyseq</B> | |
6091 | ||
6092 | differs from | |
6093 | <B>keyname</B> | |
6094 | ||
6095 | above in that strings denoting | |
6096 | an entire key sequence may be specified by placing the sequence | |
6097 | within double quotes. Some GNU Emacs style key escapes can be | |
6098 | used, as in the following example, but the symbolic character names | |
6099 | are not recognized. | |
6100 | <P> | |
6101 | <DL COMPACT><DT><DD> | |
6102 | "\C-u": universal-argument | |
6103 | <BR> | |
6104 | ||
6105 | "\C-x\C-r": re-read-init-file | |
6106 | <BR> | |
6107 | ||
6108 | "\e[11~": "Function Key 1" | |
6109 | </DL> | |
6110 | ||
6111 | <P> | |
6112 | ||
6113 | In this example, | |
6114 | <I>C-u</I> | |
6115 | ||
6116 | is again bound to the function | |
6117 | <B>universal-argument</B>. | |
6118 | ||
6119 | <I>C-x C-r</I> | |
6120 | ||
6121 | is bound to the function | |
6122 | <B>re-read-init-file</B>, | |
6123 | ||
6124 | and | |
6125 | <I>ESC [ 1 1 ~</I> | |
6126 | ||
6127 | is bound to insert the text | |
6128 | <TT>Function Key 1</TT>. | |
6129 | ||
6130 | <P> | |
6131 | ||
6132 | The full set of GNU Emacs style escape sequences is | |
6133 | <DL COMPACT><DT><DD> | |
6134 | ||
6135 | <DL COMPACT> | |
6136 | <DT><B>\C-</B> | |
6137 | ||
6138 | <DD> | |
6139 | control prefix | |
6140 | <DT><B>\M-</B> | |
6141 | ||
6142 | <DD> | |
6143 | meta prefix | |
6144 | <DT><B>\e</B> | |
6145 | ||
6146 | <DD> | |
6147 | an escape character | |
6148 | <DT><B>\\</B> | |
6149 | ||
6150 | <DD> | |
6151 | backslash | |
6152 | <DT><B>\</B> | |
6153 | ||
6154 | <DD> | |
6155 | literal " | |
6156 | <DT><B>\aq</B> | |
6157 | ||
6158 | <DD> | |
6159 | literal aq | |
6160 | </DL></DL> | |
6161 | ||
6162 | ||
6163 | <P> | |
6164 | ||
6165 | In addition to the GNU Emacs style escape sequences, a second | |
6166 | set of backslash escapes is available: | |
6167 | <DL COMPACT><DT><DD> | |
6168 | ||
6169 | <DL COMPACT> | |
6170 | <DT><B>\a</B> | |
6171 | ||
6172 | <DD> | |
6173 | alert (bell) | |
6174 | <DT><B>\b</B> | |
6175 | ||
6176 | <DD> | |
6177 | backspace | |
6178 | <DT><B>\d</B> | |
6179 | ||
6180 | <DD> | |
6181 | delete | |
6182 | <DT><B>\f</B> | |
6183 | ||
6184 | <DD> | |
6185 | form feed | |
6186 | <DT><B>\n</B> | |
6187 | ||
6188 | <DD> | |
6189 | newline | |
6190 | <DT><B>\r</B> | |
6191 | ||
6192 | <DD> | |
6193 | carriage return | |
6194 | <DT><B>\t</B> | |
6195 | ||
6196 | <DD> | |
6197 | horizontal tab | |
6198 | <DT><B>\v</B> | |
6199 | ||
6200 | <DD> | |
6201 | vertical tab | |
6202 | <DT><B>\</B><I>nnn</I> | |
6203 | ||
6204 | <DD> | |
6205 | the eight-bit character whose value is the octal value <I>nnn</I> | |
6206 | (one to three digits) | |
6207 | <DT><B>\x</B><I>HH</I> | |
6208 | ||
6209 | <DD> | |
6210 | the eight-bit character whose value is the hexadecimal value <I>HH</I> | |
6211 | (one or two hex digits) | |
6212 | </DL></DL> | |
6213 | ||
6214 | ||
6215 | <P> | |
6216 | ||
6217 | When entering the text of a macro, single or double quotes must | |
6218 | be used to indicate a macro definition. | |
6219 | Unquoted text is assumed to be a function name. | |
6220 | In the macro body, the backslash escapes described above are expanded. | |
6221 | Backslash will quote any other character in the macro text, | |
6222 | including " and aq. | |
6223 | <P> | |
6224 | ||
6225 | <B>Bash</B> | |
6226 | ||
6227 | allows the current readline key bindings to be displayed or modified | |
6228 | with the | |
6229 | <B>bind</B> | |
6230 | ||
6231 | builtin command. The editing mode may be switched during interactive | |
6232 | use by using the | |
6233 | <B>-o</B> | |
6234 | ||
6235 | option to the | |
6236 | <B>set</B> | |
6237 | ||
6238 | builtin command (see | |
6239 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
6240 | ||
6241 | </FONT> | |
6242 | below). | |
6243 | <A NAME="lbCJ"> </A> | |
6244 | <H4>Readline Variables</H4> | |
6245 | ||
6246 | <P> | |
6247 | ||
6248 | Readline has variables that can be used to further customize its | |
6249 | behavior. A variable may be set in the | |
6250 | <I>inputrc</I> | |
6251 | ||
6252 | file with a statement of the form | |
6253 | <DL COMPACT><DT><DD> | |
6254 | <P> | |
6255 | ||
6256 | <B>set</B> <I>variable-name</I> <I>value</I> | |
6257 | </DL> | |
6258 | ||
6259 | <P> | |
6260 | ||
6261 | Except where noted, readline variables can take the values | |
6262 | <B>On</B> | |
6263 | ||
6264 | or | |
6265 | <B>Off</B> | |
6266 | ||
6267 | (without regard to case). | |
6268 | Unrecognized variable names are ignored. | |
6269 | When a variable value is read, empty or null values, "on" (case-insensitive), | |
6270 | and "1" are equivalent to <B>On</B>. All other values are equivalent to | |
6271 | <B>Off</B>. | |
6272 | The variables and their default values are: | |
6273 | <P> | |
6274 | ||
6275 | ||
6276 | <DL COMPACT> | |
6277 | <DT><B>bell-style (audible)</B> | |
6278 | ||
6279 | <DD> | |
6280 | Controls what happens when readline wants to ring the terminal bell. | |
6281 | If set to <B>none</B>, readline never rings the bell. If set to | |
6282 | <B>visible</B>, readline uses a visible bell if one is available. | |
6283 | If set to <B>audible</B>, readline attempts to ring the terminal's bell. | |
6284 | <DT><B>bind-tty-special-chars (On)</B> | |
6285 | ||
6286 | <DD> | |
6287 | If set to <B>On</B>, readline attempts to bind the control characters | |
6288 | treated specially by the kernel's terminal driver to their readline | |
6289 | equivalents. | |
6290 | <DT><B>comment-begin (``#'')</B> | |
6291 | ||
6292 | <DD> | |
6293 | The string that is inserted when the readline | |
6294 | <B>insert-comment</B> | |
6295 | ||
6296 | command is executed. | |
6297 | This command is bound to | |
6298 | <B>M-#</B> | |
6299 | ||
6300 | in emacs mode and to | |
6301 | <B>#</B> | |
6302 | ||
6303 | in vi command mode. | |
6304 | <DT><B>completion-ignore-case (Off)</B> | |
6305 | ||
6306 | <DD> | |
6307 | If set to <B>On</B>, readline performs filename matching and completion | |
6308 | in a case-insensitive fashion. | |
6309 | <DT><B>completion-prefix-display-length (0)</B> | |
6310 | ||
6311 | <DD> | |
6312 | The length in characters of the common prefix of a list of possible | |
6313 | completions that is displayed without modification. When set to a | |
6314 | value greater than zero, common prefixes longer than this value are | |
6315 | replaced with an ellipsis when displaying possible completions. | |
6316 | <DT><B>completion-query-items (100)</B> | |
6317 | ||
6318 | <DD> | |
6319 | This determines when the user is queried about viewing | |
6320 | the number of possible completions | |
6321 | generated by the <B>possible-completions</B> command. | |
6322 | It may be set to any integer value greater than or equal to | |
6323 | zero. If the number of possible completions is greater than | |
6324 | or equal to the value of this variable, the user is asked whether | |
6325 | or not he wishes to view them; otherwise they are simply listed | |
6326 | on the terminal. | |
6327 | <DT><B>convert-meta (On)</B> | |
6328 | ||
6329 | <DD> | |
6330 | If set to <B>On</B>, readline will convert characters with the | |
6331 | eighth bit set to an ASCII key sequence | |
6332 | by stripping the eighth bit and prefixing an | |
6333 | escape character (in effect, using escape as the <I>meta prefix</I>). | |
6334 | <DT><B>disable-completion (Off)</B> | |
6335 | ||
6336 | <DD> | |
6337 | If set to <B>On</B>, readline will inhibit word completion. Completion | |
6338 | characters will be inserted into the line as if they had been | |
6339 | mapped to <B>self-insert</B>. | |
6340 | <DT><B>editing-mode (emacs)</B> | |
6341 | ||
6342 | <DD> | |
6343 | Controls whether readline begins with a set of key bindings similar | |
6344 | to <I>emacs</I> or <I>vi</I>. | |
6345 | <B>editing-mode</B> | |
6346 | ||
6347 | can be set to either | |
6348 | <B>emacs</B> | |
6349 | ||
6350 | or | |
6351 | <B>vi</B>. | |
6352 | ||
6353 | <DT><B>enable-keypad (Off)</B> | |
6354 | ||
6355 | <DD> | |
6356 | When set to <B>On</B>, readline will try to enable the application | |
6357 | keypad when it is called. Some systems need this to enable the | |
6358 | arrow keys. | |
6359 | <DT><B>expand-tilde (Off)</B> | |
6360 | ||
6361 | <DD> | |
6362 | If set to <B>on</B>, tilde expansion is performed when readline | |
6363 | attempts word completion. | |
6364 | <DT><B>history-preserve-point (Off)</B> | |
6365 | ||
6366 | <DD> | |
6367 | If set to <B>on</B>, the history code attempts to place point at the | |
6368 | same location on each history line retrieved with <B>previous-history</B> | |
6369 | or <B>next-history</B>. | |
6370 | <DT><B>history-size (0)</B> | |
6371 | ||
6372 | <DD> | |
6373 | Set the maximum number of history entries saved in the history list. If | |
6374 | set to zero, the number of entries in the history list is not limited. | |
6375 | <DT><B>horizontal-scroll-mode (Off)</B> | |
6376 | ||
6377 | <DD> | |
6378 | When set to <B>On</B>, makes readline use a single line for display, | |
6379 | scrolling the input horizontally on a single screen line when it | |
6380 | becomes longer than the screen width rather than wrapping to a new line. | |
6381 | <DT><B>input-meta (Off)</B> | |
6382 | ||
6383 | <DD> | |
6384 | If set to <B>On</B>, readline will enable eight-bit input (that is, | |
6385 | it will not strip the high bit from the characters it reads), | |
6386 | regardless of what the terminal claims it can support. The name | |
6387 | <B>meta-flag</B> | |
6388 | ||
6389 | is a synonym for this variable. | |
6390 | <DT><B>isearch-terminators (``C-[C-J'')</B> | |
6391 | ||
6392 | <DD> | |
6393 | The string of characters that should terminate an incremental | |
6394 | search without subsequently executing the character as a command. | |
6395 | If this variable has not been given a value, the characters | |
6396 | <I>ESC</I> and <I>C-J</I> will terminate an incremental search. | |
6397 | <DT><B>keymap (emacs)</B> | |
6398 | ||
6399 | <DD> | |
6400 | Set the current readline keymap. The set of valid keymap names is | |
6401 | <I>emacs, emacs-standard, emacs-meta, emacs-ctlx, vi, | |
6402 | vi-command</I>, and | |
6403 | <I>vi-insert</I>. | |
6404 | ||
6405 | <I>vi</I> is equivalent to <I>vi-command</I>; <I>emacs</I> is | |
6406 | equivalent to <I>emacs-standard</I>. The default value is | |
6407 | <I>emacs</I>; | |
6408 | ||
6409 | the value of | |
6410 | <B>editing-mode</B> | |
6411 | ||
6412 | also affects the default keymap. | |
6413 | <DT><B>mark-directories (On)</B> | |
6414 | ||
6415 | <DD> | |
6416 | If set to <B>On</B>, completed directory names have a slash | |
6417 | appended. | |
6418 | <DT><B>mark-modified-lines (Off)</B> | |
6419 | ||
6420 | <DD> | |
6421 | If set to <B>On</B>, history lines that have been modified are displayed | |
6422 | with a preceding asterisk (<B>*</B>). | |
6423 | <DT><B>mark-symlinked-directories (Off)</B> | |
6424 | ||
6425 | <DD> | |
6426 | If set to <B>On</B>, completed names which are symbolic links to directories | |
6427 | have a slash appended (subject to the value of | |
6428 | <B>mark-directories</B>). | |
6429 | <DT><B>match-hidden-files (On)</B> | |
6430 | ||
6431 | <DD> | |
6432 | This variable, when set to <B>On</B>, causes readline to match files whose | |
6433 | names begin with a `.' (hidden files) when performing filename | |
6434 | completion, unless the leading `.' is | |
6435 | supplied by the user in the filename to be completed. | |
6436 | <DT><B>output-meta (Off)</B> | |
6437 | ||
6438 | <DD> | |
6439 | If set to <B>On</B>, readline will display characters with the | |
6440 | eighth bit set directly rather than as a meta-prefixed escape | |
6441 | sequence. | |
6442 | <DT><B>page-completions (On)</B> | |
6443 | ||
6444 | <DD> | |
6445 | If set to <B>On</B>, readline uses an internal <I>more</I>-like pager | |
6446 | to display a screenful of possible completions at a time. | |
6447 | <DT><B>print-completions-horizontally (Off)</B> | |
6448 | ||
6449 | <DD> | |
6450 | If set to <B>On</B>, readline will display completions with matches | |
6451 | sorted horizontally in alphabetical order, rather than down the screen. | |
6452 | <DT><B>revert-all-at-newline (Off)</B> | |
6453 | ||
6454 | <DD> | |
6455 | If set to <B>on</B>, readline will undo all changes to history lines | |
6456 | before returning when <B>accept-line</B> is executed. By default, | |
6457 | history lines may be modified and retain individual undo lists across | |
6458 | calls to <B>readline</B>. | |
6459 | <DT><B>show-all-if-ambiguous (Off)</B> | |
6460 | ||
6461 | <DD> | |
6462 | This alters the default behavior of the completion functions. If | |
6463 | set to | |
6464 | <B>on</B>, | |
6465 | ||
6466 | words which have more than one possible completion cause the | |
6467 | matches to be listed immediately instead of ringing the bell. | |
6468 | <DT><B>show-all-if-unmodified (Off)</B> | |
6469 | ||
6470 | <DD> | |
6471 | This alters the default behavior of the completion functions in | |
6472 | a fashion similar to <B>show-all-if-ambiguous</B>. | |
6473 | If set to | |
6474 | <B>on</B>, | |
6475 | ||
6476 | words which have more than one possible completion without any | |
6477 | possible partial completion (the possible completions don't share | |
6478 | a common prefix) cause the matches to be listed immediately instead | |
6479 | of ringing the bell. | |
6480 | <DT><B>visible-stats (Off)</B> | |
6481 | ||
6482 | <DD> | |
6483 | If set to <B>On</B>, a character denoting a file's type as reported | |
6484 | by <I>stat</I>(2) is appended to the filename when listing possible | |
6485 | completions. | |
6486 | ||
6487 | </DL> | |
6488 | <A NAME="lbCK"> </A> | |
6489 | <H4>Readline Conditional Constructs</H4> | |
6490 | ||
6491 | <P> | |
6492 | ||
6493 | Readline implements a facility similar in spirit to the conditional | |
6494 | compilation features of the C preprocessor which allows key | |
6495 | bindings and variable settings to be performed as the result | |
6496 | of tests. There are four parser directives used. | |
6497 | <DL COMPACT> | |
6498 | <DT><B>$if</B><DD> | |
6499 | The | |
6500 | <B>$if</B> | |
6501 | ||
6502 | construct allows bindings to be made based on the | |
6503 | editing mode, the terminal being used, or the application using | |
6504 | readline. The text of the test extends to the end of the line; | |
6505 | no characters are required to isolate it. | |
6506 | <DL COMPACT><DT><DD> | |
6507 | <DL COMPACT> | |
6508 | <DT><B>mode</B><DD> | |
6509 | The <B>mode=</B> form of the <B>$if</B> directive is used to test | |
6510 | whether readline is in emacs or vi mode. | |
6511 | This may be used in conjunction | |
6512 | with the <B>set keymap</B> command, for instance, to set bindings in | |
6513 | the <I>emacs-standard</I> and <I>emacs-ctlx</I> keymaps only if | |
6514 | readline is starting out in emacs mode. | |
6515 | <DT><B>term</B><DD> | |
6516 | The <B>term=</B> form may be used to include terminal-specific | |
6517 | key bindings, perhaps to bind the key sequences output by the | |
6518 | terminal's function keys. The word on the right side of the | |
6519 | <B>=</B> | |
6520 | ||
6521 | is tested against the both full name of the terminal and the portion | |
6522 | of the terminal name before the first <B>-</B>. This allows | |
6523 | <I>sun</I> | |
6524 | ||
6525 | to match both | |
6526 | <I>sun</I> | |
6527 | ||
6528 | and | |
6529 | <I>sun-cmd</I>, | |
6530 | ||
6531 | for instance. | |
6532 | <DT><B>application</B><DD> | |
6533 | The <B>application</B> construct is used to include | |
6534 | application-specific settings. Each program using the readline | |
6535 | library sets the <I>application name</I>, and an initialization | |
6536 | file can test for a particular value. | |
6537 | This could be used to bind key sequences to functions useful for | |
6538 | a specific program. For instance, the following command adds a | |
6539 | key sequence that quotes the current or previous word in Bash: | |
6540 | <P> | |
6541 | <DL COMPACT><DT><DD> | |
6542 | <PRE> | |
6543 | <B>$if</B> Bash | |
6544 | # Quote the current or previous word | |
6545 | "\C-xq": "\eb\"\ef\"" | |
6546 | <B>$endif</B> | |
6547 | </PRE> | |
6548 | ||
6549 | </DL> | |
6550 | ||
6551 | </DL></DL> | |
6552 | ||
6553 | <DT><B>$endif</B><DD> | |
6554 | This command, as seen in the previous example, terminates an | |
6555 | <B>$if</B> command. | |
6556 | <DT><B>$else</B><DD> | |
6557 | Commands in this branch of the <B>$if</B> directive are executed if | |
6558 | the test fails. | |
6559 | <DT><B>$include</B><DD> | |
6560 | This directive takes a single filename as an argument and reads commands | |
6561 | and bindings from that file. For example, the following directive | |
6562 | would read <A HREF="file:/etc/inputrc"><I>/etc/inputrc</I></A>: | |
6563 | <P> | |
6564 | <DL COMPACT><DT><DD> | |
6565 | <PRE> | |
6566 | <B>$include</B> <A HREF="file:/etc/inputrc"><I>/etc/inputrc</I></A> | |
6567 | </PRE> | |
6568 | ||
6569 | </DL> | |
6570 | ||
6571 | </DL> | |
6572 | <A NAME="lbCL"> </A> | |
6573 | <H4>Searching</H4> | |
6574 | ||
6575 | <P> | |
6576 | ||
6577 | Readline provides commands for searching through the command history | |
6578 | (see | |
6579 | <FONT SIZE=-1><B>HISTORY</B> | |
6580 | ||
6581 | </FONT> | |
6582 | below) for lines containing a specified string. | |
6583 | There are two search modes: | |
6584 | <I>incremental</I> | |
6585 | ||
6586 | and | |
6587 | <I>non-incremental</I>. | |
6588 | ||
6589 | <P> | |
6590 | ||
6591 | Incremental searches begin before the user has finished typing the | |
6592 | search string. | |
6593 | As each character of the search string is typed, readline displays | |
6594 | the next entry from the history matching the string typed so far. | |
6595 | An incremental search requires only as many characters as needed to | |
6596 | find the desired history entry. | |
6597 | The characters present in the value of the <B>isearch-terminators</B> | |
6598 | variable are used to terminate an incremental search. | |
6599 | If that variable has not been assigned a value the Escape and | |
6600 | Control-J characters will terminate an incremental search. | |
6601 | Control-G will abort an incremental search and restore the original | |
6602 | line. | |
6603 | When the search is terminated, the history entry containing the | |
6604 | search string becomes the current line. | |
6605 | <P> | |
6606 | ||
6607 | To find other matching entries in the history list, type Control-S or | |
6608 | Control-R as appropriate. | |
6609 | This will search backward or forward in the history for the next | |
6610 | entry matching the search string typed so far. | |
6611 | Any other key sequence bound to a readline command will terminate | |
6612 | the search and execute that command. | |
6613 | For instance, a <I>newline</I> will terminate the search and accept | |
6614 | the line, thereby executing the command from the history list. | |
6615 | <P> | |
6616 | ||
6617 | Readline remembers the last incremental search string. If two | |
6618 | Control-Rs are typed without any intervening characters defining a | |
6619 | new search string, any remembered search string is used. | |
6620 | <P> | |
6621 | ||
6622 | Non-incremental searches read the entire search string before starting | |
6623 | to search for matching history lines. The search string may be | |
6624 | typed by the user or be part of the contents of the current line. | |
6625 | <A NAME="lbCM"> </A> | |
6626 | <H4>Readline Command Names</H4> | |
6627 | ||
6628 | <P> | |
6629 | ||
6630 | The following is a list of the names of the commands and the default | |
6631 | key sequences to which they are bound. | |
6632 | Command names without an accompanying key sequence are unbound by default. | |
6633 | In the following descriptions, <I>point</I> refers to the current cursor | |
6634 | position, and <I>mark</I> refers to a cursor position saved by the | |
6635 | <B>set-mark</B> command. | |
6636 | The text between the point and mark is referred to as the <I>region</I>. | |
6637 | <A NAME="lbCN"> </A> | |
6638 | <H4>Commands for Moving</H4> | |
6639 | ||
6640 | <P> | |
6641 | ||
6642 | ||
6643 | <DL COMPACT> | |
6644 | <DT><B>beginning-of-line (C-a)</B> | |
6645 | ||
6646 | <DD> | |
6647 | Move to the start of the current line. | |
6648 | <DT><B>end-of-line (C-e)</B> | |
6649 | ||
6650 | <DD> | |
6651 | Move to the end of the line. | |
6652 | <DT><B>forward-char (C-f)</B> | |
6653 | ||
6654 | <DD> | |
6655 | Move forward a character. | |
6656 | <DT><B>backward-char (C-b)</B> | |
6657 | ||
6658 | <DD> | |
6659 | Move back a character. | |
6660 | <DT><B>forward-word (M-f)</B> | |
6661 | ||
6662 | <DD> | |
6663 | Move forward to the end of the next word. Words are composed of | |
6664 | alphanumeric characters (letters and digits). | |
6665 | <DT><B>backward-word (M-b)</B> | |
6666 | ||
6667 | <DD> | |
6668 | Move back to the start of the current or previous word. | |
6669 | Words are composed of alphanumeric characters (letters and digits). | |
6670 | <DT><B>shell-forward-word</B> | |
6671 | ||
6672 | <DD> | |
6673 | Move forward to the end of the next word. | |
6674 | Words are delimited by non-quoted shell metacharacters. | |
6675 | <DT><B>shell-backward-word</B> | |
6676 | ||
6677 | <DD> | |
6678 | Move back to the start of the current or previous word. | |
6679 | Words are delimited by non-quoted shell metacharacters. | |
6680 | <DT><B>clear-screen (C-l)</B> | |
6681 | ||
6682 | <DD> | |
6683 | Clear the screen leaving the current line at the top of the screen. | |
6684 | With an argument, refresh the current line without clearing the | |
6685 | screen. | |
6686 | <DT><B>redraw-current-line</B> | |
6687 | ||
6688 | <DD> | |
6689 | Refresh the current line. | |
6690 | ||
6691 | </DL> | |
6692 | <A NAME="lbCO"> </A> | |
6693 | <H4>Commands for Manipulating the History</H4> | |
6694 | ||
6695 | <P> | |
6696 | ||
6697 | ||
6698 | <DL COMPACT> | |
6699 | <DT><B>accept-line (Newline, Return)</B> | |
6700 | ||
6701 | <DD> | |
6702 | Accept the line regardless of where the cursor is. If this line is | |
6703 | non-empty, add it to the history list according to the state of the | |
6704 | <FONT SIZE=-1><B>HISTCONTROL</B> | |
6705 | ||
6706 | </FONT> | |
6707 | variable. If the line is a modified history | |
6708 | line, then restore the history line to its original state. | |
6709 | <DT><B>previous-history (C-p)</B> | |
6710 | ||
6711 | <DD> | |
6712 | Fetch the previous command from the history list, moving back in | |
6713 | the list. | |
6714 | <DT><B>next-history (C-n)</B> | |
6715 | ||
6716 | <DD> | |
6717 | Fetch the next command from the history list, moving forward in the | |
6718 | list. | |
6719 | <DT><B>beginning-of-history (M-<)</B> | |
6720 | ||
6721 | <DD> | |
6722 | Move to the first line in the history. | |
6723 | <DT><B>end-of-history (M->)</B> | |
6724 | ||
6725 | <DD> | |
6726 | Move to the end of the input history, i.e., the line currently being | |
6727 | entered. | |
6728 | <DT><B>reverse-search-history (C-r)</B> | |
6729 | ||
6730 | <DD> | |
6731 | Search backward starting at the current line and moving `up' through | |
6732 | the history as necessary. This is an incremental search. | |
6733 | <DT><B>forward-search-history (C-s)</B> | |
6734 | ||
6735 | <DD> | |
6736 | Search forward starting at the current line and moving `down' through | |
6737 | the history as necessary. This is an incremental search. | |
6738 | <DT><B>non-incremental-reverse-search-history (M-p)</B> | |
6739 | ||
6740 | <DD> | |
6741 | Search backward through the history starting at the current line | |
6742 | using a non-incremental search for a string supplied by the user. | |
6743 | <DT><B>non-incremental-forward-search-history (M-n)</B> | |
6744 | ||
6745 | <DD> | |
6746 | Search forward through the history using a non-incremental search for | |
6747 | a string supplied by the user. | |
6748 | <DT><B>history-search-forward</B> | |
6749 | ||
6750 | <DD> | |
6751 | Search forward through the history for the string of characters | |
6752 | between the start of the current line and the point. | |
6753 | This is a non-incremental search. | |
6754 | <DT><B>history-search-backward</B> | |
6755 | ||
6756 | <DD> | |
6757 | Search backward through the history for the string of characters | |
6758 | between the start of the current line and the point. | |
6759 | This is a non-incremental search. | |
6760 | <DT><B>yank-nth-arg (M-C-y)</B> | |
6761 | ||
6762 | <DD> | |
6763 | Insert the first argument to the previous command (usually | |
6764 | the second word on the previous line) at point. | |
6765 | With an argument | |
6766 | <I>n</I>, | |
6767 | ||
6768 | insert the <I>n</I>th word from the previous command (the words | |
6769 | in the previous command begin with word 0). A negative argument | |
6770 | inserts the <I>n</I>th word from the end of the previous command. | |
6771 | Once the argument <I>n</I> is computed, the argument is extracted | |
6772 | as if the "!<I>n</I>" history expansion had been specified. | |
6773 | <DT><B>yank-last-arg (M-., M-_)</B> | |
6774 | ||
6775 | <DD> | |
6776 | Insert the last argument to the previous command (the last word of | |
6777 | the previous history entry). With an argument, | |
6778 | behave exactly like <B>yank-nth-arg</B>. | |
6779 | Successive calls to <B>yank-last-arg</B> move back through the history | |
6780 | list, inserting the last argument of each line in turn. | |
6781 | The history expansion facilities are used to extract the last argument, | |
6782 | as if the "!$" history expansion had been specified. | |
6783 | <DT><B>shell-expand-line (M-C-e)</B> | |
6784 | ||
6785 | <DD> | |
6786 | Expand the line as the shell does. This | |
6787 | performs alias and history expansion as well as all of the shell | |
6788 | word expansions. See | |
6789 | <FONT SIZE=-1><B>HISTORY EXPANSION</B> | |
6790 | ||
6791 | </FONT> | |
6792 | below for a description of history expansion. | |
6793 | <DT><B>history-expand-line (M-^)</B> | |
6794 | ||
6795 | <DD> | |
6796 | Perform history expansion on the current line. | |
6797 | See | |
6798 | <FONT SIZE=-1><B>HISTORY EXPANSION</B> | |
6799 | ||
6800 | </FONT> | |
6801 | below for a description of history expansion. | |
6802 | <DT><B>magic-space</B> | |
6803 | ||
6804 | <DD> | |
6805 | Perform history expansion on the current line and insert a space. | |
6806 | See | |
6807 | <FONT SIZE=-1><B>HISTORY EXPANSION</B> | |
6808 | ||
6809 | </FONT> | |
6810 | below for a description of history expansion. | |
6811 | <DT><B>alias-expand-line</B> | |
6812 | ||
6813 | <DD> | |
6814 | Perform alias expansion on the current line. | |
6815 | See | |
6816 | <FONT SIZE=-1><B>ALIASES</B> | |
6817 | ||
6818 | </FONT> | |
6819 | above for a description of alias expansion. | |
6820 | <DT><B>history-and-alias-expand-line</B> | |
6821 | ||
6822 | <DD> | |
6823 | Perform history and alias expansion on the current line. | |
6824 | <DT><B>insert-last-argument (M-., M-_)</B> | |
6825 | ||
6826 | <DD> | |
6827 | A synonym for <B>yank-last-arg</B>. | |
6828 | <DT><B>operate-and-get-next (C-o)</B> | |
6829 | ||
6830 | <DD> | |
6831 | Accept the current line for execution and fetch the next line | |
6832 | relative to the current line from the history for editing. Any | |
6833 | argument is ignored. | |
6834 | <DT><B>edit-and-execute-command (C-xC-e)</B> | |
6835 | ||
6836 | <DD> | |
6837 | Invoke an editor on the current command line, and execute the result as shell | |
6838 | commands. | |
6839 | <B>Bash</B> attempts to invoke | |
6840 | <FONT SIZE=-1><B>$VISUAL</B>, | |
6841 | ||
6842 | </FONT> | |
6843 | <FONT SIZE=-1><B>$EDITOR</B>, | |
6844 | ||
6845 | </FONT> | |
6846 | and <I>emacs</I> as the editor, in that order. | |
6847 | ||
6848 | </DL> | |
6849 | <A NAME="lbCP"> </A> | |
6850 | <H4>Commands for Changing Text</H4> | |
6851 | ||
6852 | <P> | |
6853 | ||
6854 | ||
6855 | <DL COMPACT> | |
6856 | <DT><B>delete-char (C-d)</B> | |
6857 | ||
6858 | <DD> | |
6859 | Delete the character at point. If point is at the | |
6860 | beginning of the line, there are no characters in the line, and | |
6861 | the last character typed was not bound to <B>delete-char</B>, | |
6862 | then return | |
6863 | <FONT SIZE=-1><B>EOF</B>. | |
6864 | ||
6865 | </FONT> | |
6866 | <DT><B>backward-delete-char (Rubout)</B> | |
6867 | ||
6868 | <DD> | |
6869 | Delete the character behind the cursor. When given a numeric argument, | |
6870 | save the deleted text on the kill ring. | |
6871 | <DT><B>forward-backward-delete-char</B> | |
6872 | ||
6873 | <DD> | |
6874 | Delete the character under the cursor, unless the cursor is at the | |
6875 | end of the line, in which case the character behind the cursor is | |
6876 | deleted. | |
6877 | <DT><B>quoted-insert (C-q, C-v)</B> | |
6878 | ||
6879 | <DD> | |
6880 | Add the next character typed to the line verbatim. This is | |
6881 | how to insert characters like <B>C-q</B>, for example. | |
6882 | <DT><B>tab-insert (C-v TAB)</B> | |
6883 | ||
6884 | <DD> | |
6885 | Insert a tab character. | |
6886 | <DT><B>self-insert (a, b, A, 1, !, ...)</B> | |
6887 | ||
6888 | <DD> | |
6889 | Insert the character typed. | |
6890 | <DT><B>transpose-chars (C-t)</B> | |
6891 | ||
6892 | <DD> | |
6893 | Drag the character before point forward over the character at point, | |
6894 | moving point forward as well. | |
6895 | If point is at the end of the line, then this transposes | |
6896 | the two characters before point. | |
6897 | Negative arguments have no effect. | |
6898 | <DT><B>transpose-words (M-t)</B> | |
6899 | ||
6900 | <DD> | |
6901 | Drag the word before point past the word after point, | |
6902 | moving point over that word as well. | |
6903 | If point is at the end of the line, this transposes | |
6904 | the last two words on the line. | |
6905 | <DT><B>upcase-word (M-u)</B> | |
6906 | ||
6907 | <DD> | |
6908 | Uppercase the current (or following) word. With a negative argument, | |
6909 | uppercase the previous word, but do not move point. | |
6910 | <DT><B>downcase-word (M-l)</B> | |
6911 | ||
6912 | <DD> | |
6913 | Lowercase the current (or following) word. With a negative argument, | |
6914 | lowercase the previous word, but do not move point. | |
6915 | <DT><B>capitalize-word (M-c)</B> | |
6916 | ||
6917 | <DD> | |
6918 | Capitalize the current (or following) word. With a negative argument, | |
6919 | capitalize the previous word, but do not move point. | |
6920 | <DT><B>overwrite-mode</B> | |
6921 | ||
6922 | <DD> | |
6923 | Toggle overwrite mode. With an explicit positive numeric argument, | |
6924 | switches to overwrite mode. With an explicit non-positive numeric | |
6925 | argument, switches to insert mode. This command affects only | |
6926 | <B>emacs</B> mode; <B>vi</B> mode does overwrite differently. | |
6927 | Each call to <I>readline()</I> starts in insert mode. | |
6928 | In overwrite mode, characters bound to <B>self-insert</B> replace | |
6929 | the text at point rather than pushing the text to the right. | |
6930 | Characters bound to <B>backward-delete-char</B> replace the character | |
6931 | before point with a space. By default, this command is unbound. | |
6932 | ||
6933 | </DL> | |
6934 | <A NAME="lbCQ"> </A> | |
6935 | <H4>Killing and Yanking</H4> | |
6936 | ||
6937 | <P> | |
6938 | ||
6939 | ||
6940 | <DL COMPACT> | |
6941 | <DT><B>kill-line (C-k)</B> | |
6942 | ||
6943 | <DD> | |
6944 | Kill the text from point to the end of the line. | |
6945 | <DT><B>backward-kill-line (C-x Rubout)</B> | |
6946 | ||
6947 | <DD> | |
6948 | Kill backward to the beginning of the line. | |
6949 | <DT><B>unix-line-discard (C-u)</B> | |
6950 | ||
6951 | <DD> | |
6952 | Kill backward from point to the beginning of the line. | |
6953 | The killed text is saved on the kill-ring. | |
6954 | ||
6955 | <DT><B>kill-whole-line</B> | |
6956 | ||
6957 | <DD> | |
6958 | Kill all characters on the current line, no matter where point is. | |
6959 | <DT><B>kill-word (M-d)</B> | |
6960 | ||
6961 | <DD> | |
6962 | Kill from point to the end of the current word, or if between | |
6963 | words, to the end of the next word. | |
6964 | Word boundaries are the same as those used by <B>forward-word</B>. | |
6965 | <DT><B>backward-kill-word (M-Rubout)</B> | |
6966 | ||
6967 | <DD> | |
6968 | Kill the word behind point. | |
6969 | Word boundaries are the same as those used by <B>backward-word</B>. | |
6970 | <DT><B>shell-kill-word (M-d)</B> | |
6971 | ||
6972 | <DD> | |
6973 | Kill from point to the end of the current word, or if between | |
6974 | words, to the end of the next word. | |
6975 | Word boundaries are the same as those used by <B>shell-forward-word</B>. | |
6976 | <DT><B>shell-backward-kill-word (M-Rubout)</B> | |
6977 | ||
6978 | <DD> | |
6979 | Kill the word behind point. | |
6980 | Word boundaries are the same as those used by <B>shell-backward-word</B>. | |
6981 | <DT><B>unix-word-rubout (C-w)</B> | |
6982 | ||
6983 | <DD> | |
6984 | Kill the word behind point, using white space as a word boundary. | |
6985 | The killed text is saved on the kill-ring. | |
6986 | <DT><B>unix-filename-rubout</B> | |
6987 | ||
6988 | <DD> | |
6989 | Kill the word behind point, using white space and the slash character | |
6990 | as the word boundaries. | |
6991 | The killed text is saved on the kill-ring. | |
6992 | <DT><B>delete-horizontal-space (M-\)</B> | |
6993 | ||
6994 | <DD> | |
6995 | Delete all spaces and tabs around point. | |
6996 | <DT><B>kill-region</B> | |
6997 | ||
6998 | <DD> | |
6999 | Kill the text in the current region. | |
7000 | <DT><B>copy-region-as-kill</B> | |
7001 | ||
7002 | <DD> | |
7003 | Copy the text in the region to the kill buffer. | |
7004 | <DT><B>copy-backward-word</B> | |
7005 | ||
7006 | <DD> | |
7007 | Copy the word before point to the kill buffer. | |
7008 | The word boundaries are the same as <B>backward-word</B>. | |
7009 | <DT><B>copy-forward-word</B> | |
7010 | ||
7011 | <DD> | |
7012 | Copy the word following point to the kill buffer. | |
7013 | The word boundaries are the same as <B>forward-word</B>. | |
7014 | <DT><B>yank (C-y)</B> | |
7015 | ||
7016 | <DD> | |
7017 | Yank the top of the kill ring into the buffer at point. | |
7018 | <DT><B>yank-pop (M-y)</B> | |
7019 | ||
7020 | <DD> | |
7021 | Rotate the kill ring, and yank the new top. Only works following | |
7022 | <B>yank</B> | |
7023 | ||
7024 | or | |
7025 | <B>yank-pop</B>. | |
7026 | ||
7027 | ||
7028 | </DL> | |
7029 | <A NAME="lbCR"> </A> | |
7030 | <H4>Numeric Arguments</H4> | |
7031 | ||
7032 | <P> | |
7033 | ||
7034 | ||
7035 | <DL COMPACT> | |
7036 | <DT><B>digit-argument (M-0, M-1, ..., M--)</B> | |
7037 | ||
7038 | <DD> | |
7039 | Add this digit to the argument already accumulating, or start a new | |
7040 | argument. M-- starts a negative argument. | |
7041 | <DT><B>universal-argument</B> | |
7042 | ||
7043 | <DD> | |
7044 | This is another way to specify an argument. | |
7045 | If this command is followed by one or more digits, optionally with a | |
7046 | leading minus sign, those digits define the argument. | |
7047 | If the command is followed by digits, executing | |
7048 | <B>universal-argument</B> | |
7049 | ||
7050 | again ends the numeric argument, but is otherwise ignored. | |
7051 | As a special case, if this command is immediately followed by a | |
7052 | character that is neither a digit or minus sign, the argument count | |
7053 | for the next command is multiplied by four. | |
7054 | The argument count is initially one, so executing this function the | |
7055 | first time makes the argument count four, a second time makes the | |
7056 | argument count sixteen, and so on. | |
7057 | ||
7058 | </DL> | |
7059 | <A NAME="lbCS"> </A> | |
7060 | <H4>Completing</H4> | |
7061 | ||
7062 | <P> | |
7063 | ||
7064 | ||
7065 | <DL COMPACT> | |
7066 | <DT><B>complete (TAB)</B> | |
7067 | ||
7068 | <DD> | |
7069 | Attempt to perform completion on the text before point. | |
7070 | <B>Bash</B> | |
7071 | ||
7072 | attempts completion treating the text as a variable (if the | |
7073 | text begins with <B>$</B>), username (if the text begins with | |
7074 | <B>~</B>), hostname (if the text begins with <B>@</B>), or | |
7075 | command (including aliases and functions) in turn. If none | |
7076 | of these produces a match, filename completion is attempted. | |
7077 | <DT><B>possible-completions (M-?)</B> | |
7078 | ||
7079 | <DD> | |
7080 | List the possible completions of the text before point. | |
7081 | <DT><B>insert-completions (M-*)</B> | |
7082 | ||
7083 | <DD> | |
7084 | Insert all completions of the text before point | |
7085 | that would have been generated by | |
7086 | <B>possible-completions</B>. | |
7087 | <DT><B>menu-complete</B> | |
7088 | ||
7089 | <DD> | |
7090 | Similar to <B>complete</B>, but replaces the word to be completed | |
7091 | with a single match from the list of possible completions. | |
7092 | Repeated execution of <B>menu-complete</B> steps through the list | |
7093 | of possible completions, inserting each match in turn. | |
7094 | At the end of the list of completions, the bell is rung | |
7095 | (subject to the setting of <B>bell-style</B>) | |
7096 | and the original text is restored. | |
7097 | An argument of <I>n</I> moves <I>n</I> positions forward in the list | |
7098 | of matches; a negative argument may be used to move backward | |
7099 | through the list. | |
7100 | This command is intended to be bound to <B>TAB</B>, but is unbound | |
7101 | by default. | |
7102 | <DT><B>delete-char-or-list</B> | |
7103 | ||
7104 | <DD> | |
7105 | Deletes the character under the cursor if not at the beginning or | |
7106 | end of the line (like <B>delete-char</B>). | |
7107 | If at the end of the line, behaves identically to | |
7108 | <B>possible-completions</B>. | |
7109 | This command is unbound by default. | |
7110 | <DT><B>complete-filename (M-/)</B> | |
7111 | ||
7112 | <DD> | |
7113 | Attempt filename completion on the text before point. | |
7114 | <DT><B>possible-filename-completions (C-x /)</B> | |
7115 | ||
7116 | <DD> | |
7117 | List the possible completions of the text before point, | |
7118 | treating it as a filename. | |
7119 | <DT><B>complete-username (M-~)</B> | |
7120 | ||
7121 | <DD> | |
7122 | Attempt completion on the text before point, treating | |
7123 | it as a username. | |
7124 | <DT><B>possible-username-completions (C-x ~)</B> | |
7125 | ||
7126 | <DD> | |
7127 | List the possible completions of the text before point, | |
7128 | treating it as a username. | |
7129 | <DT><B>complete-variable (M-$)</B> | |
7130 | ||
7131 | <DD> | |
7132 | Attempt completion on the text before point, treating | |
7133 | it as a shell variable. | |
7134 | <DT><B>possible-variable-completions (C-x $)</B> | |
7135 | ||
7136 | <DD> | |
7137 | List the possible completions of the text before point, | |
7138 | treating it as a shell variable. | |
7139 | <DT><B>complete-hostname (M-@)</B> | |
7140 | ||
7141 | <DD> | |
7142 | Attempt completion on the text before point, treating | |
7143 | it as a hostname. | |
7144 | <DT><B>possible-hostname-completions (C-x @)</B> | |
7145 | ||
7146 | <DD> | |
7147 | List the possible completions of the text before point, | |
7148 | treating it as a hostname. | |
7149 | <DT><B>complete-command (M-!)</B> | |
7150 | ||
7151 | <DD> | |
7152 | Attempt completion on the text before point, treating | |
7153 | it as a command name. Command completion attempts to | |
7154 | match the text against aliases, reserved words, shell | |
7155 | functions, shell builtins, and finally executable filenames, | |
7156 | in that order. | |
7157 | <DT><B>possible-command-completions (C-x !)</B> | |
7158 | ||
7159 | <DD> | |
7160 | List the possible completions of the text before point, | |
7161 | treating it as a command name. | |
7162 | <DT><B>dynamic-complete-history (M-TAB)</B> | |
7163 | ||
7164 | <DD> | |
7165 | Attempt completion on the text before point, comparing | |
7166 | the text against lines from the history list for possible | |
7167 | completion matches. | |
7168 | <DT><B>dabbrev-expand</B> | |
7169 | ||
7170 | <DD> | |
7171 | Attempt menu completion on the text before point, comparing | |
7172 | the text against lines from the history list for possible | |
7173 | completion matches. | |
7174 | <DT><B>complete-into-braces (M-{)</B> | |
7175 | ||
7176 | <DD> | |
7177 | Perform filename completion and insert the list of possible completions | |
7178 | enclosed within braces so the list is available to the shell (see | |
7179 | <B>Brace Expansion</B> | |
7180 | ||
7181 | above). | |
7182 | ||
7183 | </DL> | |
7184 | <A NAME="lbCT"> </A> | |
7185 | <H4>Keyboard Macros</H4> | |
7186 | ||
7187 | <P> | |
7188 | ||
7189 | ||
7190 | <DL COMPACT> | |
7191 | <DT><B>start-kbd-macro (C-x ()</B> | |
7192 | ||
7193 | <DD> | |
7194 | Begin saving the characters typed into the current keyboard macro. | |
7195 | <DT><B>end-kbd-macro (C-x ))</B> | |
7196 | ||
7197 | <DD> | |
7198 | Stop saving the characters typed into the current keyboard macro | |
7199 | and store the definition. | |
7200 | <DT><B>call-last-kbd-macro (C-x e)</B> | |
7201 | ||
7202 | <DD> | |
7203 | Re-execute the last keyboard macro defined, by making the characters | |
7204 | in the macro appear as if typed at the keyboard. | |
7205 | ||
7206 | </DL> | |
7207 | <A NAME="lbCU"> </A> | |
7208 | <H4>Miscellaneous</H4> | |
7209 | ||
7210 | <P> | |
7211 | ||
7212 | ||
7213 | <DL COMPACT> | |
7214 | <DT><B>re-read-init-file (C-x C-r)</B> | |
7215 | ||
7216 | <DD> | |
7217 | Read in the contents of the <I>inputrc</I> file, and incorporate | |
7218 | any bindings or variable assignments found there. | |
7219 | <DT><B>abort (C-g)</B> | |
7220 | ||
7221 | <DD> | |
7222 | Abort the current editing command and | |
7223 | ring the terminal's bell (subject to the setting of | |
7224 | <B>bell-style</B>). | |
7225 | ||
7226 | <DT><B>do-uppercase-version (M-a, M-b, M-</B><I>x</I>, ...) | |
7227 | ||
7228 | <DD> | |
7229 | If the metafied character <I>x</I> is lowercase, run the command | |
7230 | that is bound to the corresponding uppercase character. | |
7231 | <DT><B>prefix-meta (ESC)</B> | |
7232 | ||
7233 | <DD> | |
7234 | Metafy the next character typed. | |
7235 | <FONT SIZE=-1><B>ESC</B> | |
7236 | ||
7237 | </FONT> | |
7238 | <B>f</B> | |
7239 | ||
7240 | is equivalent to | |
7241 | <B>Meta-f</B>. | |
7242 | ||
7243 | <DT><B>undo (C-_, C-x C-u)</B> | |
7244 | ||
7245 | <DD> | |
7246 | Incremental undo, separately remembered for each line. | |
7247 | <DT><B>revert-line (M-r)</B> | |
7248 | ||
7249 | <DD> | |
7250 | Undo all changes made to this line. This is like executing the | |
7251 | <B>undo</B> | |
7252 | ||
7253 | command enough times to return the line to its initial state. | |
7254 | <DT><B>tilde-expand (M-&)</B> | |
7255 | ||
7256 | <DD> | |
7257 | Perform tilde expansion on the current word. | |
7258 | <DT><B>set-mark (C-@, M-<space>)</B> | |
7259 | ||
7260 | <DD> | |
7261 | Set the mark to the point. If a | |
7262 | numeric argument is supplied, the mark is set to that position. | |
7263 | <DT><B>exchange-point-and-mark (C-x C-x)</B> | |
7264 | ||
7265 | <DD> | |
7266 | Swap the point with the mark. The current cursor position is set to | |
7267 | the saved position, and the old cursor position is saved as the mark. | |
7268 | <DT><B>character-search (C-])</B> | |
7269 | ||
7270 | <DD> | |
7271 | A character is read and point is moved to the next occurrence of that | |
7272 | character. A negative count searches for previous occurrences. | |
7273 | <DT><B>character-search-backward (M-C-])</B> | |
7274 | ||
7275 | <DD> | |
7276 | A character is read and point is moved to the previous occurrence of that | |
7277 | character. A negative count searches for subsequent occurrences. | |
7278 | <DT><B>insert-comment (M-#)</B> | |
7279 | ||
7280 | <DD> | |
7281 | Without a numeric argument, the value of the readline | |
7282 | <B>comment-begin</B> | |
7283 | ||
7284 | variable is inserted at the beginning of the current line. | |
7285 | If a numeric argument is supplied, this command acts as a toggle: if | |
7286 | the characters at the beginning of the line do not match the value | |
7287 | of <B>comment-begin</B>, the value is inserted, otherwise | |
7288 | the characters in <B>comment-begin</B> are deleted from the beginning of | |
7289 | the line. | |
7290 | In either case, the line is accepted as if a newline had been typed. | |
7291 | The default value of | |
7292 | <B>comment-begin</B> causes this command to make the current line | |
7293 | a shell comment. | |
7294 | If a numeric argument causes the comment character to be removed, the line | |
7295 | will be executed by the shell. | |
7296 | <DT><B>glob-complete-word (M-g)</B> | |
7297 | ||
7298 | <DD> | |
7299 | The word before point is treated as a pattern for pathname expansion, | |
7300 | with an asterisk implicitly appended. This pattern is used to | |
7301 | generate a list of matching file names for possible completions. | |
7302 | <DT><B>glob-expand-word (C-x *)</B> | |
7303 | ||
7304 | <DD> | |
7305 | The word before point is treated as a pattern for pathname expansion, | |
7306 | and the list of matching file names is inserted, replacing the word. | |
7307 | If a numeric argument is supplied, an asterisk is appended before | |
7308 | pathname expansion. | |
7309 | <DT><B>glob-list-expansions (C-x g)</B> | |
7310 | ||
7311 | <DD> | |
7312 | The list of expansions that would have been generated by | |
7313 | <B>glob-expand-word</B> | |
7314 | ||
7315 | is displayed, and the line is redrawn. | |
7316 | If a numeric argument is supplied, an asterisk is appended before | |
7317 | pathname expansion. | |
7318 | <DT><B>dump-functions</B> | |
7319 | ||
7320 | <DD> | |
7321 | Print all of the functions and their key bindings to the | |
7322 | readline output stream. If a numeric argument is supplied, | |
7323 | the output is formatted in such a way that it can be made part | |
7324 | of an <I>inputrc</I> file. | |
7325 | <DT><B>dump-variables</B> | |
7326 | ||
7327 | <DD> | |
7328 | Print all of the settable readline variables and their values to the | |
7329 | readline output stream. If a numeric argument is supplied, | |
7330 | the output is formatted in such a way that it can be made part | |
7331 | of an <I>inputrc</I> file. | |
7332 | <DT><B>dump-macros</B> | |
7333 | ||
7334 | <DD> | |
7335 | Print all of the readline key sequences bound to macros and the | |
7336 | strings they output. If a numeric argument is supplied, | |
7337 | the output is formatted in such a way that it can be made part | |
7338 | of an <I>inputrc</I> file. | |
7339 | <DT><B>display-shell-version (C-x C-v)</B> | |
7340 | ||
7341 | <DD> | |
7342 | Display version information about the current instance of | |
7343 | <B>bash</B>. | |
7344 | ||
7345 | ||
7346 | </DL> | |
7347 | <A NAME="lbCV"> </A> | |
7348 | <H4>Programmable Completion</H4> | |
7349 | ||
7350 | <P> | |
7351 | ||
7352 | When word completion is attempted for an argument to a command for | |
7353 | which a completion specification (a <I>compspec</I>) has been defined | |
7354 | using the <B>complete</B> builtin (see | |
7355 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
7356 | ||
7357 | </FONT> | |
7358 | below), the programmable completion facilities are invoked. | |
7359 | <P> | |
7360 | ||
7361 | First, the command name is identified. | |
7362 | If a compspec has been defined for that command, the | |
7363 | compspec is used to generate the list of possible completions for the word. | |
7364 | If the command word is a full pathname, a compspec for the full | |
7365 | pathname is searched for first. | |
7366 | If no compspec is found for the full pathname, an attempt is made to | |
7367 | find a compspec for the portion following the final slash. | |
7368 | <P> | |
7369 | ||
7370 | Once a compspec has been found, it is used to generate the list of | |
7371 | matching words. | |
7372 | If a compspec is not found, the default <B>bash</B> completion as | |
7373 | described above under <B>Completing</B> is performed. | |
7374 | <P> | |
7375 | ||
7376 | First, the actions specified by the compspec are used. | |
7377 | Only matches which are prefixed by the word being completed are | |
7378 | returned. | |
7379 | When the | |
7380 | <B>-f</B> | |
7381 | ||
7382 | or | |
7383 | <B>-d</B> | |
7384 | ||
7385 | option is used for filename or directory name completion, the shell | |
7386 | variable | |
7387 | <FONT SIZE=-1><B>FIGNORE</B> | |
7388 | ||
7389 | </FONT> | |
7390 | is used to filter the matches. | |
7391 | <P> | |
7392 | ||
7393 | Any completions specified by a filename expansion pattern to the | |
7394 | <B>-G</B> option are generated next. | |
7395 | The words generated by the pattern need not match the word | |
7396 | being completed. | |
7397 | The | |
7398 | <FONT SIZE=-1><B>GLOBIGNORE</B> | |
7399 | ||
7400 | </FONT> | |
7401 | shell variable is not used to filter the matches, but the | |
7402 | <FONT SIZE=-1><B>FIGNORE</B> | |
7403 | ||
7404 | </FONT> | |
7405 | variable is used. | |
7406 | <P> | |
7407 | ||
7408 | Next, the string specified as the argument to the <B>-W</B> option | |
7409 | is considered. | |
7410 | The string is first split using the characters in the | |
7411 | <FONT SIZE=-1><B>IFS</B> | |
7412 | ||
7413 | </FONT> | |
7414 | special variable as delimiters. | |
7415 | Shell quoting is honored. | |
7416 | Each word is then expanded using | |
7417 | brace expansion, tilde expansion, parameter and variable expansion, | |
7418 | command substitution, and arithmetic expansion, | |
7419 | as described above under | |
7420 | <FONT SIZE=-1><B>EXPANSION</B>. | |
7421 | ||
7422 | </FONT> | |
7423 | The results are split using the rules described above under | |
7424 | <B>Word Splitting</B>. | |
7425 | The results of the expansion are prefix-matched against the word being | |
7426 | completed, and the matching words become the possible completions. | |
7427 | <P> | |
7428 | ||
7429 | After these matches have been generated, any shell function or command | |
7430 | specified with the <B>-F</B> and <B>-C</B> options is invoked. | |
7431 | When the command or function is invoked, the | |
7432 | <FONT SIZE=-1><B>COMP_LINE</B>, | |
7433 | ||
7434 | </FONT> | |
7435 | <FONT SIZE=-1><B>COMP_POINT</B>, | |
7436 | ||
7437 | </FONT> | |
7438 | <FONT SIZE=-1><B>COMP_KEY</B>, | |
7439 | ||
7440 | </FONT> | |
7441 | and | |
7442 | <FONT SIZE=-1><B>COMP_TYPE</B> | |
7443 | ||
7444 | </FONT> | |
7445 | variables are assigned values as described above under | |
7446 | <B>Shell Variables</B>. | |
7447 | If a shell function is being invoked, the | |
7448 | <FONT SIZE=-1><B>COMP_WORDS</B> | |
7449 | ||
7450 | </FONT> | |
7451 | and | |
7452 | <FONT SIZE=-1><B>COMP_CWORD</B> | |
7453 | ||
7454 | </FONT> | |
7455 | variables are also set. | |
7456 | When the function or command is invoked, the first argument is the | |
7457 | name of the command whose arguments are being completed, the | |
7458 | second argument is the word being completed, and the third argument | |
7459 | is the word preceding the word being completed on the current command line. | |
7460 | No filtering of the generated completions against the word being completed | |
7461 | is performed; the function or command has complete freedom in generating | |
7462 | the matches. | |
7463 | <P> | |
7464 | ||
7465 | Any function specified with <B>-F</B> is invoked first. | |
7466 | The function may use any of the shell facilities, including the | |
7467 | <B>compgen</B> builtin described below, to generate the matches. | |
7468 | It must put the possible completions in the | |
7469 | <FONT SIZE=-1><B>COMPREPLY</B> | |
7470 | ||
7471 | </FONT> | |
7472 | array variable. | |
7473 | <P> | |
7474 | ||
7475 | Next, any command specified with the <B>-C</B> option is invoked | |
7476 | in an environment equivalent to command substitution. | |
7477 | It should print a list of completions, one per line, to the | |
7478 | standard output. | |
7479 | Backslash may be used to escape a newline, if necessary. | |
7480 | <P> | |
7481 | ||
7482 | After all of the possible completions are generated, any filter | |
7483 | specified with the <B>-X</B> option is applied to the list. | |
7484 | The filter is a pattern as used for pathname expansion; a <B>&</B> | |
7485 | in the pattern is replaced with the text of the word being completed. | |
7486 | A literal <B>&</B> may be escaped with a backslash; the backslash | |
7487 | is removed before attempting a match. | |
7488 | Any completion that matches the pattern will be removed from the list. | |
7489 | A leading <B>!</B> negates the pattern; in this case any completion | |
7490 | not matching the pattern will be removed. | |
7491 | <P> | |
7492 | ||
7493 | Finally, any prefix and suffix specified with the <B>-P</B> and <B>-S</B> | |
7494 | options are added to each member of the completion list, and the result is | |
7495 | returned to the readline completion code as the list of possible | |
7496 | completions. | |
7497 | <P> | |
7498 | ||
7499 | If the previously-applied actions do not generate any matches, and the | |
7500 | <B>-o dirnames</B> option was supplied to <B>complete</B> when the | |
7501 | compspec was defined, directory name completion is attempted. | |
7502 | <P> | |
7503 | ||
7504 | If the <B>-o plusdirs</B> option was supplied to <B>complete</B> when the | |
7505 | compspec was defined, directory name completion is attempted and any | |
7506 | matches are added to the results of the other actions. | |
7507 | <P> | |
7508 | ||
7509 | By default, if a compspec is found, whatever it generates is returned | |
7510 | to the completion code as the full set of possible completions. | |
7511 | The default <B>bash</B> completions are not attempted, and the readline | |
7512 | default of filename completion is disabled. | |
7513 | If the <B>-o bashdefault</B> option was supplied to <B>complete</B> when | |
7514 | the compspec was defined, the <B>bash</B> default completions are attempted | |
7515 | if the compspec generates no matches. | |
7516 | If the <B>-o default</B> option was supplied to <B>complete</B> when the | |
7517 | compspec was defined, readline's default completion will be performed | |
7518 | if the compspec (and, if attempted, the default <B>bash</B> completions) | |
7519 | generate no matches. | |
7520 | <P> | |
7521 | ||
7522 | When a compspec indicates that directory name completion is desired, | |
7523 | the programmable completion functions force readline to append a slash | |
7524 | to completed names which are symbolic links to directories, subject to | |
7525 | the value of the <B>mark-directories</B> readline variable, regardless | |
7526 | of the setting of the <B>mark-symlinked-directories</B> readline variable. | |
7527 | <A NAME="lbCW"> </A> | |
7528 | <H3>HISTORY</H3> | |
7529 | ||
7530 | When the | |
7531 | <B>-o history</B> | |
7532 | ||
7533 | option to the | |
7534 | <B>set</B> | |
7535 | ||
7536 | builtin is enabled, the shell provides access to the | |
7537 | <I>command history</I>, | |
7538 | the list of commands previously typed. | |
7539 | The value of the <B>HISTSIZE</B> variable is used as the | |
7540 | number of commands to save in a history list. | |
7541 | The text of the last | |
7542 | <FONT SIZE=-1><B>HISTSIZE</B> | |
7543 | ||
7544 | </FONT> | |
7545 | commands (default 500) is saved. The shell | |
7546 | stores each command in the history list prior to parameter and | |
7547 | variable expansion (see | |
7548 | <FONT SIZE=-1><B>EXPANSION</B> | |
7549 | ||
7550 | </FONT> | |
7551 | above) but after history expansion is performed, subject to the | |
7552 | values of the shell variables | |
7553 | <FONT SIZE=-1><B>HISTIGNORE</B> | |
7554 | ||
7555 | </FONT> | |
7556 | and | |
7557 | <FONT SIZE=-1><B>HISTCONTROL</B>. | |
7558 | ||
7559 | </FONT> | |
7560 | <P> | |
7561 | ||
7562 | On startup, the history is initialized from the file named by | |
7563 | the variable | |
7564 | <FONT SIZE=-1><B>HISTFILE</B> | |
7565 | ||
7566 | </FONT> | |
7567 | (default <A HREF="file:~/.bash_history"><I>~/.bash_history</I></A>). | |
7568 | The file named by the value of | |
7569 | <FONT SIZE=-1><B>HISTFILE</B> | |
7570 | ||
7571 | </FONT> | |
7572 | is truncated, if necessary, to contain no more than | |
7573 | the number of lines specified by the value of | |
7574 | <FONT SIZE=-1><B>HISTFILESIZE</B>. | |
7575 | ||
7576 | </FONT> | |
7577 | When the history file is read, | |
7578 | lines beginning with the history comment character followed immediately | |
7579 | by a digit are interpreted as timestamps for the preceding history line. | |
7580 | These timestamps are optionally displayed depending on the value of the | |
7581 | <FONT SIZE=-1><B>HISTTIMEFORMAT</B> | |
7582 | ||
7583 | </FONT> | |
7584 | variable. | |
7585 | When an interactive shell exits, the last | |
7586 | <FONT SIZE=-1><B>$HISTSIZE</B> | |
7587 | ||
7588 | </FONT> | |
7589 | lines are copied from the history list to | |
7590 | <FONT SIZE=-1><B>$HISTFILE</B>. | |
7591 | ||
7592 | </FONT> | |
7593 | If the | |
7594 | <B>histappend</B> | |
7595 | ||
7596 | shell option is enabled | |
7597 | (see the description of | |
7598 | <B>shopt</B> | |
7599 | ||
7600 | under | |
7601 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
7602 | ||
7603 | </FONT> | |
7604 | below), the lines are appended to the history file, | |
7605 | otherwise the history file is overwritten. | |
7606 | If | |
7607 | <FONT SIZE=-1><B>HISTFILE</B> | |
7608 | ||
7609 | </FONT> | |
7610 | is unset, or if the history file is unwritable, the history is | |
7611 | not saved. | |
7612 | If the | |
7613 | <FONT SIZE=-1> | |
7614 | </FONT> | |
7615 | variable is set, time stamps are written to the history file, marked | |
7616 | with the history comment character, so | |
7617 | they may be preserved across shell sessions. | |
7618 | This uses the history comment character to distinguish timestamps from | |
7619 | other history lines. | |
7620 | After saving the history, the history file is truncated | |
7621 | to contain no more than | |
7622 | <FONT SIZE=-1><B>HISTFILESIZE</B> | |
7623 | ||
7624 | </FONT> | |
7625 | lines. If | |
7626 | <FONT SIZE=-1><B>HISTFILESIZE</B> | |
7627 | ||
7628 | </FONT> | |
7629 | is not set, no truncation is performed. | |
7630 | <P> | |
7631 | ||
7632 | The builtin command | |
7633 | <B>fc</B> | |
7634 | ||
7635 | (see | |
7636 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
7637 | ||
7638 | </FONT> | |
7639 | below) may be used to list or edit and re-execute a portion of | |
7640 | the history list. | |
7641 | The | |
7642 | <B>history</B> | |
7643 | ||
7644 | builtin may be used to display or modify the history list and | |
7645 | manipulate the history file. | |
7646 | When using command-line editing, search commands | |
7647 | are available in each editing mode that provide access to the | |
7648 | history list. | |
7649 | <P> | |
7650 | ||
7651 | The shell allows control over which commands are saved on the history | |
7652 | list. The | |
7653 | <FONT SIZE=-1><B>HISTCONTROL</B> | |
7654 | ||
7655 | </FONT> | |
7656 | and | |
7657 | <FONT SIZE=-1><B>HISTIGNORE</B> | |
7658 | ||
7659 | </FONT> | |
7660 | variables may be set to cause the shell to save only a subset of the | |
7661 | commands entered. | |
7662 | The | |
7663 | <B>cmdhist</B> | |
7664 | ||
7665 | shell option, if enabled, causes the shell to attempt to save each | |
7666 | line of a multi-line command in the same history entry, adding | |
7667 | semicolons where necessary to preserve syntactic correctness. | |
7668 | The | |
7669 | <B>lithist</B> | |
7670 | ||
7671 | shell option causes the shell to save the command with embedded newlines | |
7672 | instead of semicolons. See the description of the | |
7673 | <B>shopt</B> | |
7674 | ||
7675 | builtin below under | |
7676 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
7677 | ||
7678 | </FONT> | |
7679 | for information on setting and unsetting shell options. | |
7680 | <A NAME="lbCX"> </A> | |
7681 | <H3>HISTORY EXPANSION</H3> | |
7682 | ||
7683 | <P> | |
7684 | ||
7685 | The shell supports a history expansion feature that | |
7686 | is similar to the history expansion in | |
7687 | <B>csh.</B> | |
7688 | ||
7689 | This section describes what syntax features are available. This | |
7690 | feature is enabled by default for interactive shells, and can be | |
7691 | disabled using the | |
7692 | <B>+H</B> | |
7693 | ||
7694 | option to the | |
7695 | <B>set</B> | |
7696 | ||
7697 | builtin command (see | |
7698 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> | |
7699 | ||
7700 | </FONT> | |
7701 | below). Non-interactive shells do not perform history expansion | |
7702 | by default. | |
7703 | <P> | |
7704 | ||
7705 | History expansions introduce words from the history list into | |
7706 | the input stream, making it easy to repeat commands, insert the | |
7707 | arguments to a previous command into the current input line, or | |
7708 | fix errors in previous commands quickly. | |
7709 | <P> | |
7710 | ||
7711 | History expansion is performed immediately after a complete line | |
7712 | is read, before the shell breaks it into words. | |
7713 | It takes place in two parts. | |
7714 | The first is to determine which line from the history list | |
7715 | to use during substitution. | |
7716 | The second is to select portions of that line for inclusion into | |
7717 | the current one. | |
7718 | The line selected from the history is the <I>event</I>, | |
7719 | and the portions of that line that are acted upon are <I>words</I>. | |
7720 | Various <I>modifiers</I> are available to manipulate the selected words. | |
7721 | The line is broken into words in the same fashion as when reading input, | |
7722 | so that several <I>metacharacter</I>-separated words surrounded by | |
7723 | quotes are considered one word. | |
7724 | History expansions are introduced by the appearance of the | |
7725 | history expansion character, which is <B>!</B> by default. | |
7726 | Only backslash (<B>\</B>) and single quotes can quote | |
7727 | the history expansion character. | |
7728 | <P> | |
7729 | ||
7730 | Several characters inhibit history expansion if found immediately | |
7731 | following the history expansion character, even if it is unquoted: | |
7732 | space, tab, newline, carriage return, and <B>=</B>. | |
7733 | If the <B>extglob</B> shell option is enabled, <B>(</B> will also | |
7734 | inhibit expansion. | |
7735 | <P> | |
7736 | ||
7737 | Several shell options settable with the | |
7738 | <B>shopt</B> | |
7739 | ||
7740 | builtin may be used to tailor the behavior of history expansion. | |
7741 | If the | |
7742 | <B>histverify</B> | |
7743 | ||
7744 | shell option is enabled (see the description of the | |
7745 | <B>shopt</B> | |
7746 | ||
7747 | builtin), and | |
7748 | <B>readline</B> | |
7749 | ||
7750 | is being used, history substitutions are not immediately passed to | |
7751 | the shell parser. | |
7752 | Instead, the expanded line is reloaded into the | |
7753 | <B>readline</B> | |
7754 | ||
7755 | editing buffer for further modification. | |
7756 | If | |
7757 | <B>readline</B> | |
7758 | ||
7759 | is being used, and the | |
7760 | <B>histreedit</B> | |
7761 | ||
7762 | shell option is enabled, a failed history substitution will be reloaded | |
7763 | into the | |
7764 | <B>readline</B> | |
7765 | ||
7766 | editing buffer for correction. | |
7767 | The | |
7768 | <B>-p</B> | |
7769 | ||
7770 | option to the | |
7771 | <B>history</B> | |
7772 | ||
7773 | builtin command may be used to see what a history expansion will | |
7774 | do before using it. | |
7775 | The | |
7776 | <B>-s</B> | |
7777 | ||
7778 | option to the | |
7779 | <B>history</B> | |
7780 | ||
7781 | builtin may be used to add commands to the end of the history list | |
7782 | without actually executing them, so that they are available for | |
7783 | subsequent recall. | |
7784 | <P> | |
7785 | ||
7786 | The shell allows control of the various characters used by the | |
7787 | history expansion mechanism (see the description of | |
7788 | <B>histchars</B> | |
7789 | ||
7790 | above under | |
7791 | <B>Shell Variables</B>). | |
7792 | ||
7793 | The shell uses | |
7794 | the history comment character to mark history timestamps when | |
7795 | writing the history file. | |
7796 | <A NAME="lbCY"> </A> | |
7797 | <H4>Event Designators</H4> | |
7798 | ||
7799 | <P> | |
7800 | ||
7801 | An event designator is a reference to a command line entry in the | |
7802 | history list. | |
7803 | <P> | |
7804 | ||
7805 | ||
7806 | <DL COMPACT> | |
7807 | <DT><B>!</B> | |
7808 | ||
7809 | <DD> | |
7810 | Start a history substitution, except when followed by a | |
7811 | <B>blank</B>, | |
7812 | ||
7813 | newline, carriage return, = | |
7814 | or ( (when the <B>extglob</B> shell option is enabled using | |
7815 | the <B>shopt</B> builtin). | |
7816 | <DT><B>!</B><I>n</I> | |
7817 | ||
7818 | <DD> | |
7819 | Refer to command line | |
7820 | <I>n</I>. | |
7821 | ||
7822 | <DT><B>!-</B><I>n</I> | |
7823 | ||
7824 | <DD> | |
7825 | Refer to the current command line minus | |
7826 | <I>n</I>. | |
7827 | ||
7828 | <DT><B>!!</B> | |
7829 | ||
7830 | <DD> | |
7831 | Refer to the previous command. This is a synonym for `!-1'. | |
7832 | <DT><B>!</B><I>string</I> | |
7833 | ||
7834 | <DD> | |
7835 | Refer to the most recent command starting with | |
7836 | <I>string</I>. | |
7837 | ||
7838 | <DT><B>!?</B><I>string</I><B>[?]</B> | |
7839 | ||
7840 | <DD> | |
7841 | Refer to the most recent command containing | |
7842 | <I>string</I>. | |
7843 | ||
7844 | The trailing <B>?</B> may be omitted if | |
7845 | <I>string</I> | |
7846 | ||
7847 | is followed immediately by a newline. | |
7848 | <DT><B></B><FONT SIZE=+2><B>^</B></FONT><B></B><I>string1</I><FONT SIZE=+2>^</FONT><I>string2</I><FONT SIZE=+2>^</FONT> | |
7849 | ||
7850 | <DD> | |
7851 | Quick substitution. Repeat the last command, replacing | |
7852 | <I>string1</I> | |
7853 | ||
7854 | with | |
7855 | <I>string2</I>. | |
7856 | ||
7857 | Equivalent to | |
7858 | ``!!:s/<I>string1</I>/<I>string2</I>/'' | |
7859 | (see <B>Modifiers</B> below). | |
7860 | <DT><B>!#</B> | |
7861 | ||
7862 | <DD> | |
7863 | The entire command line typed so far. | |
7864 | ||
7865 | </DL> | |
7866 | <A NAME="lbCZ"> </A> | |
7867 | <H4>Word Designators</H4> | |
7868 | ||
7869 | <P> | |
7870 | ||
7871 | Word designators are used to select desired words from the event. | |
7872 | A | |
7873 | <B>:</B> | |
7874 | ||
7875 | separates the event specification from the word designator. | |
7876 | It may be omitted if the word designator begins with a | |
7877 | <B>^</B>, | |
7878 | ||
7879 | <B>$</B>, | |
7880 | ||
7881 | <B>*</B>, | |
7882 | ||
7883 | <B>-</B>, | |
7884 | ||
7885 | or | |
7886 | <B>%</B>. | |
7887 | ||
7888 | Words are numbered from the beginning of the line, | |
7889 | with the first word being denoted by 0 (zero). | |
7890 | Words are inserted into the current line separated by single spaces. | |
7891 | <P> | |
7892 | ||
7893 | ||
7894 | <DL COMPACT> | |
7895 | <DT><B>0 (zero)</B> | |
7896 | ||
7897 | <DD> | |
7898 | The zeroth word. For the shell, this is the command | |
7899 | word. | |
7900 | <DT><I>n</I> | |
7901 | ||
7902 | <DD> | |
7903 | The <I>n</I>th word. | |
7904 | <DT><B>^</B> | |
7905 | ||
7906 | <DD> | |
7907 | The first argument. That is, word 1. | |
7908 | <DT><B>$</B> | |
7909 | ||
7910 | <DD> | |
7911 | The last argument. | |
7912 | <DT><B>%</B> | |
7913 | ||
7914 | <DD> | |
7915 | The word matched by the most recent `?<I>string</I>?' search. | |
7916 | <DT><I>x</I><B>-</B>y | |
7917 | ||
7918 | <DD> | |
7919 | A range of words; `-<I>y</I>' abbreviates `0-<I>y</I>'. | |
7920 | <DT><B>*</B> | |
7921 | ||
7922 | <DD> | |
7923 | All of the words but the zeroth. This is a synonym | |
7924 | for `<I>1-$</I>'. It is not an error to use | |
7925 | <B>*</B> | |
7926 | ||
7927 | if there is just one | |
7928 | word in the event; the empty string is returned in that case. | |
7929 | <DT><B>x*</B> | |
7930 | ||
7931 | <DD> | |
7932 | Abbreviates <I>x-$</I>. | |
7933 | <DT><B>x-</B> | |
7934 | ||
7935 | <DD> | |
7936 | Abbreviates <I>x-$</I> like <B>x*</B>, but omits the last word. | |
7937 | ||
7938 | </DL> | |
7939 | <P> | |
7940 | ||
7941 | If a word designator is supplied without an event specification, the | |
7942 | previous command is used as the event. | |
7943 | <A NAME="lbDA"> </A> | |
7944 | <H4>Modifiers</H4> | |
7945 | ||
7946 | <P> | |
7947 | ||
7948 | After the optional word designator, there may appear a sequence of | |
7949 | one or more of the following modifiers, each preceded by a `:'. | |
7950 | <P> | |
7951 | ||
7952 | ||
7953 | <P> | |
7954 | ||
7955 | <DL COMPACT> | |
7956 | <DT><B>h</B> | |
7957 | ||
7958 | <DD> | |
7959 | Remove a trailing file name component, leaving only the head. | |
7960 | <DT><B>t</B> | |
7961 | ||
7962 | <DD> | |
7963 | Remove all leading file name components, leaving the tail. | |
7964 | <DT><B>r</B> | |
7965 | ||
7966 | <DD> | |
7967 | Remove a trailing suffix of the form <I>.xxx</I>, leaving the | |
7968 | basename. | |
7969 | <DT><B>e</B> | |
7970 | ||
7971 | <DD> | |
7972 | Remove all but the trailing suffix. | |
7973 | <DT><B>p</B> | |
7974 | ||
7975 | <DD> | |
7976 | Print the new command but do not execute it. | |
7977 | <DT><B>q</B> | |
7978 | ||
7979 | <DD> | |
7980 | Quote the substituted words, escaping further substitutions. | |
7981 | <DT><B>x</B> | |
7982 | ||
7983 | <DD> | |
7984 | Quote the substituted words as with | |
7985 | <B>q</B>, | |
7986 | ||
7987 | but break into words at | |
7988 | <B>blanks</B> | |
7989 | ||
7990 | and newlines. | |
7991 | <DT><B>s/</B><I>old</I>/<I>new</I>/ | |
7992 | ||
7993 | <DD> | |
7994 | Substitute | |
7995 | <I>new</I> | |
7996 | ||
7997 | for the first occurrence of | |
7998 | <I>old</I> | |
7999 | ||
8000 | in the event line. Any delimiter can be used in place of /. The | |
8001 | final delimiter is optional if it is the last character of the | |
8002 | event line. The delimiter may be quoted in | |
8003 | <I>old</I> | |
8004 | ||
8005 | and | |
8006 | <I>new</I> | |
8007 | ||
8008 | with a single backslash. If & appears in | |
8009 | <I>new</I>, | |
8010 | ||
8011 | it is replaced by | |
8012 | <I>old</I>. | |
8013 | ||
8014 | A single backslash will quote the &. If | |
8015 | <I>old</I> | |
8016 | ||
8017 | is null, it is set to the last | |
8018 | <I>old</I> | |
8019 | ||
8020 | substituted, or, if no previous history substitutions took place, | |
8021 | the last | |
8022 | <I>string</I> | |
8023 | ||
8024 | in a | |
8025 | <B>!?</B><I>string</I><B>[?]</B> | |
8026 | ||
8027 | search. | |
8028 | <DT><B>&</B> | |
8029 | ||
8030 | <DD> | |
8031 | Repeat the previous substitution. | |
8032 | <DT><B>g</B> | |
8033 | ||
8034 | <DD> | |
8035 | Cause changes to be applied over the entire event line. This is | |
8036 | used in conjunction with `<B>:s</B>' (e.g., `<B>:gs/</B><I>old</I>/<I>new</I>/') | |
8037 | or `<B>:&</B>'. If used with | |
8038 | `<B>:s</B>', any delimiter can be used | |
8039 | in place of /, and the final delimiter is optional | |
8040 | if it is the last character of the event line. | |
8041 | An <B>a</B> may be used as a synonym for <B>g</B>. | |
8042 | <DT><B>G</B> | |
8043 | ||
8044 | <DD> | |
8045 | Apply the following `<B>s</B>' modifier once to each word in the event line. | |
8046 | ||
8047 | </DL> | |
8048 | <A NAME="lbDB"> </A> | |
8049 | <H3>SHELL BUILTIN COMMANDS</H3> | |
8050 | ||
8051 | ||
8052 | ||
8053 | <P> | |
8054 | ||
8055 | Unless otherwise noted, each builtin command documented in this | |
8056 | section as accepting options preceded by | |
8057 | <B>-</B> | |
8058 | ||
8059 | accepts | |
8060 | <B>--</B> | |
8061 | ||
8062 | to signify the end of the options. | |
8063 | For example, the <B>:</B>, <B>true</B>, <B>false</B>, and <B>test</B> builtins | |
8064 | do not accept options. | |
8065 | <P> | |
8066 | ||
8067 | <DL COMPACT> | |
8068 | <DT><B>:</B> [<I>arguments</I>]<DD> | |
8069 | ||
8070 | No effect; the command does nothing beyond expanding | |
8071 | <I>arguments</I> | |
8072 | ||
8073 | and performing any specified | |
8074 | redirections. A zero exit code is returned. | |
8075 | <DT><B> . </B> <I>filename</I> [<I>arguments</I>]<DD> | |
8076 | ||
8077 | <DT><B>source</B> <I>filename</I> [<I>arguments</I>]<DD> | |
8078 | ||
8079 | Read and execute commands from | |
8080 | <I>filename</I> | |
8081 | ||
8082 | in the current | |
8083 | shell environment and return the exit status of the last command | |
8084 | executed from | |
8085 | <I>filename</I>. | |
8086 | ||
8087 | If | |
8088 | <I>filename</I> | |
8089 | ||
8090 | does not contain a slash, file names in | |
8091 | <FONT SIZE=-1><B>PATH</B> | |
8092 | ||
8093 | </FONT> | |
8094 | are used to find the directory containing | |
8095 | <I>filename</I>. | |
8096 | ||
8097 | The file searched for in | |
8098 | <FONT SIZE=-1><B>PATH</B> | |
8099 | ||
8100 | </FONT> | |
8101 | need not be executable. | |
8102 | When <B>bash</B> is not in <I>posix mode</I>, the current directory is | |
8103 | searched if no file is found in | |
8104 | <FONT SIZE=-1><B>PATH</B>. | |
8105 | ||
8106 | </FONT> | |
8107 | If the | |
8108 | <B>sourcepath</B> | |
8109 | ||
8110 | option to the | |
8111 | <B>shopt</B> | |
8112 | ||
8113 | builtin command is turned off, the | |
8114 | <FONT SIZE=-1><B>PATH</B> | |
8115 | ||
8116 | </FONT> | |
8117 | is not searched. | |
8118 | If any <I>arguments</I> are supplied, they become the positional | |
8119 | parameters when <I>filename</I> is executed. Otherwise the positional | |
8120 | parameters are unchanged. | |
8121 | The return status is the status of the last command exited within | |
8122 | the script (0 if no commands are executed), and false if | |
8123 | <I>filename</I> | |
8124 | ||
8125 | is not found or cannot be read. | |
8126 | <DT><B>alias</B> [<B>-p</B>] [<I>name</I>[=<I>value</I>] ...]<DD> | |
8127 | <B>Alias</B> with no arguments or with the | |
8128 | <B>-p</B> | |
8129 | ||
8130 | option prints the list of aliases in the form | |
8131 | <B>alias</B> <I>name</I>=<I>value</I> on standard output. | |
8132 | When arguments are supplied, an alias is defined for | |
8133 | each <I>name</I> whose <I>value</I> is given. | |
8134 | A trailing space in <I>value</I> causes the next word to be | |
8135 | checked for alias substitution when the alias is expanded. | |
8136 | For each <I>name</I> in the argument list for which no <I>value</I> | |
8137 | is supplied, the name and value of the alias is printed. | |
8138 | <B>Alias</B> returns true unless a <I>name</I> is given for which | |
8139 | no alias has been defined. | |
8140 | <DT><B>bg</B> [<I>jobspec</I> ...]<DD> | |
8141 | Resume each suspended job <I>jobspec</I> in the background, as if it | |
8142 | had been started with | |
8143 | <B>&</B>. | |
8144 | ||
8145 | If | |
8146 | <I>jobspec</I> | |
8147 | ||
8148 | is not present, the shell's notion of the <I>current job</I> is used. | |
8149 | <B>bg</B> | |
8150 | ||
8151 | <I>jobspec</I> | |
8152 | ||
8153 | returns 0 unless run when job control is disabled or, when run with | |
8154 | job control enabled, any specified <I>jobspec</I> was not found | |
8155 | or was started without job control. | |
8156 | <DT><B>bind</B> [<B>-m</B> <I>keymap</I>] [<B>-lpsvPSV</B>]<DD> | |
8157 | ||
8158 | <DT><B>bind</B> [<B>-m</B> <I>keymap</I>] [<B>-q</B> <I>function</I>] [<B>-u</B> <I>function</I>] [<B>-r</B> <I>keyseq</I>]<DD> | |
8159 | <DT><B>bind</B> [<B>-m</B> <I>keymap</I>] <B>-f</B> <I>filename</I><DD> | |
8160 | <DT><B>bind</B> [<B>-m</B> <I>keymap</I>] <B>-x</B> <I>keyseq</I>:<I>shell-command</I><DD> | |
8161 | <DT><B>bind</B> [<B>-m</B> <I>keymap</I>] <I>keyseq</I>:<I>function-name</I><DD> | |
8162 | <DT><B>bind</B> <I>readline-command</I><DD> | |
8163 | ||
8164 | Display current | |
8165 | <B>readline</B> | |
8166 | ||
8167 | key and function bindings, bind a key sequence to a | |
8168 | <B>readline</B> | |
8169 | ||
8170 | function or macro, or set a | |
8171 | <B>readline</B> | |
8172 | ||
8173 | variable. | |
8174 | Each non-option argument is a command as it would appear in | |
8175 | <I>.inputrc</I>, | |
8176 | ||
8177 | but each binding or command must be passed as a separate argument; | |
8178 | e.g., '"\C-x\C-r": re-read-init-file'. | |
8179 | Options, if supplied, have the following meanings: | |
8180 | <DL COMPACT><DT><DD> | |
8181 | ||
8182 | <DL COMPACT> | |
8183 | <DT><B>-m </B><I>keymap</I> | |
8184 | ||
8185 | <DD> | |
8186 | Use | |
8187 | <I>keymap</I> | |
8188 | ||
8189 | as the keymap to be affected by the subsequent bindings. | |
8190 | Acceptable | |
8191 | <I>keymap</I> | |
8192 | ||
8193 | names are | |
8194 | <I>emacs, emacs-standard, emacs-meta, emacs-ctlx, vi, | |
8195 | vi-move, vi-command</I>, and | |
8196 | <I>vi-insert</I>. | |
8197 | ||
8198 | <I>vi</I> is equivalent to <I>vi-command</I>; <I>emacs</I> is | |
8199 | equivalent to <I>emacs-standard</I>. | |
8200 | <DT><B>-l</B> | |
8201 | ||
8202 | <DD> | |
8203 | List the names of all <B>readline</B> functions. | |
8204 | <DT><B>-p</B> | |
8205 | ||
8206 | <DD> | |
8207 | Display <B>readline</B> function names and bindings in such a way | |
8208 | that they can be re-read. | |
8209 | <DT><B>-P</B> | |
8210 | ||
8211 | <DD> | |
8212 | List current <B>readline</B> function names and bindings. | |
8213 | <DT><B>-s</B> | |
8214 | ||
8215 | <DD> | |
8216 | Display <B>readline</B> key sequences bound to macros and the strings | |
8217 | they output in such a way that they can be re-read. | |
8218 | <DT><B>-S</B> | |
8219 | ||
8220 | <DD> | |
8221 | Display <B>readline</B> key sequences bound to macros and the strings | |
8222 | they output. | |
8223 | <DT><B>-v</B> | |
8224 | ||
8225 | <DD> | |
8226 | Display <B>readline</B> variable names and values in such a way that they | |
8227 | can be re-read. | |
8228 | <DT><B>-V</B> | |
8229 | ||
8230 | <DD> | |
8231 | List current <B>readline</B> variable names and values. | |
8232 | <DT><B>-f </B><I>filename</I> | |
8233 | ||
8234 | <DD> | |
8235 | Read key bindings from <I>filename</I>. | |
8236 | <DT><B>-q </B><I>function</I> | |
8237 | ||
8238 | <DD> | |
8239 | Query about which keys invoke the named <I>function</I>. | |
8240 | <DT><B>-u </B><I>function</I> | |
8241 | ||
8242 | <DD> | |
8243 | Unbind all keys bound to the named <I>function</I>. | |
8244 | <DT><B>-r </B><I>keyseq</I> | |
8245 | ||
8246 | <DD> | |
8247 | Remove any current binding for <I>keyseq</I>. | |
8248 | <DT><B>-x </B><I>keyseq</I>:<I>shell-command</I> | |
8249 | ||
8250 | <DD> | |
8251 | Cause <I>shell-command</I> to be executed whenever <I>keyseq</I> is | |
8252 | entered. | |
8253 | When <I>shell-command</I> is executed, the shell sets the | |
8254 | <B>READLINE_LINE</B> | |
8255 | ||
8256 | variable to the contents of the <B>readline</B> line buffer and the | |
8257 | <B>READLINE_POINT</B> | |
8258 | ||
8259 | variable to the current location of the insertion point. | |
8260 | If the executed command changes the value of | |
8261 | <B>READLINE_LINE</B> | |
8262 | ||
8263 | or | |
8264 | <B>READLINE_POINT</B>, | |
8265 | ||
8266 | those new values will be reflected in the editing state. | |
8267 | ||
8268 | </DL> | |
8269 | <P> | |
8270 | ||
8271 | The return value is 0 unless an unrecognized option is given or an | |
8272 | error occurred. | |
8273 | </DL> | |
8274 | ||
8275 | <DT><B>break</B> [<I>n</I>]<DD> | |
8276 | Exit from within a | |
8277 | <B>for</B>, | |
8278 | ||
8279 | <B>while</B>, | |
8280 | ||
8281 | <B>until</B>, | |
8282 | ||
8283 | or | |
8284 | <B>select</B> | |
8285 | ||
8286 | loop. If <I>n</I> is specified, break <I>n</I> levels. | |
8287 | <I>n</I> | |
8288 | ||
8289 | must be >= 1. If | |
8290 | <I>n</I> | |
8291 | ||
8292 | is greater than the number of enclosing loops, all enclosing loops | |
8293 | are exited. | |
8294 | The return value is 0 unless <I>n</I> is not greater than or equal to 1. | |
8295 | <DT><B>builtin</B> <I>shell-builtin</I> [<I>arguments</I>]<DD> | |
8296 | Execute the specified shell builtin, passing it | |
8297 | <I>arguments</I>, | |
8298 | ||
8299 | and return its exit status. | |
8300 | This is useful when defining a | |
8301 | function whose name is the same as a shell builtin, | |
8302 | retaining the functionality of the builtin within the function. | |
8303 | The <B>cd</B> builtin is commonly redefined this way. | |
8304 | The return status is false if | |
8305 | <I>shell-builtin</I> | |
8306 | ||
8307 | is not a shell builtin command. | |
8308 | <DT><B>caller</B> [<I>expr</I>]<DD> | |
8309 | Returns the context of any active subroutine call (a shell function or | |
8310 | a script executed with the <B>.</B> or <B>source</B> builtins. | |
8311 | Without <I>expr</I>, <B>caller</B> displays the line number and source | |
8312 | filename of the current subroutine call. | |
8313 | If a non-negative integer is supplied as <I>expr</I>, <B>caller</B> | |
8314 | displays the line number, subroutine name, and source file corresponding | |
8315 | to that position in the current execution call stack. This extra | |
8316 | information may be used, for example, to print a stack trace. The | |
8317 | current frame is frame 0. | |
8318 | The return value is 0 unless the shell is not executing a subroutine | |
8319 | call or <I>expr</I> does not correspond to a valid position in the | |
8320 | call stack. | |
8321 | <DT><B>cd</B> [<B>-L|-P</B>] [<I>dir</I>]<DD> | |
8322 | Change the current directory to <I>dir</I>. The variable | |
8323 | <FONT SIZE=-1><B>HOME</B> | |
8324 | ||
8325 | </FONT> | |
8326 | is the | |
8327 | default | |
8328 | <I>dir</I>. | |
8329 | ||
8330 | The variable | |
8331 | <FONT SIZE=-1><B>CDPATH</B> | |
8332 | ||
8333 | </FONT> | |
8334 | defines the search path for the directory containing | |
8335 | <I>dir</I>. | |
8336 | ||
8337 | Alternative directory names in | |
8338 | <FONT SIZE=-1><B>CDPATH</B> | |
8339 | ||
8340 | </FONT> | |
8341 | are separated by a colon (:). A null directory name in | |
8342 | <FONT SIZE=-1><B>CDPATH</B> | |
8343 | ||
8344 | </FONT> | |
8345 | is the same as the current directory, i.e., ``<B>.</B>''. If | |
8346 | <I>dir</I> | |
8347 | ||
8348 | begins with a slash (/), | |
8349 | then | |
8350 | <FONT SIZE=-1><B>CDPATH</B> | |
8351 | ||
8352 | </FONT> | |
8353 | is not used. The | |
8354 | <B>-P</B> | |
8355 | ||
8356 | option says to use the physical directory structure instead of | |
8357 | following symbolic links (see also the | |
8358 | <B>-P</B> | |
8359 | ||
8360 | option to the | |
8361 | <B>set</B> | |
8362 | ||
8363 | builtin command); the | |
8364 | <B>-L</B> | |
8365 | ||
8366 | option forces symbolic links to be followed. An argument of | |
8367 | <B>-</B> | |
8368 | ||
8369 | is equivalent to | |
8370 | <FONT SIZE=-1><B>$OLDPWD</B>. | |
8371 | ||
8372 | </FONT> | |
8373 | If a non-empty directory name from <B>CDPATH</B> is used, or if | |
8374 | <B>-</B> is the first argument, and the directory change is | |
8375 | successful, the absolute pathname of the new working directory is | |
8376 | written to the standard output. | |
8377 | The return value is true if the directory was successfully changed; | |
8378 | false otherwise. | |
8379 | <DT><B>command</B> [<B>-pVv</B>] <I>command</I> [<I>arg</I> ...]<DD> | |
8380 | Run | |
8381 | <I>command</I> | |
8382 | ||
8383 | with | |
8384 | <I>args</I> | |
8385 | ||
8386 | suppressing the normal shell function lookup. Only builtin | |
8387 | commands or commands found in the | |
8388 | <FONT SIZE=-1><B>PATH</B> | |
8389 | ||
8390 | </FONT> | |
8391 | are executed. If the | |
8392 | <B>-p</B> | |
8393 | ||
8394 | option is given, the search for | |
8395 | <I>command</I> | |
8396 | ||
8397 | is performed using a default value for | |
8398 | <B>PATH</B> | |
8399 | ||
8400 | that is guaranteed to find all of the standard utilities. | |
8401 | If either the | |
8402 | <B>-V</B> | |
8403 | ||
8404 | or | |
8405 | <B>-v</B> | |
8406 | ||
8407 | option is supplied, a description of | |
8408 | <I>command</I> | |
8409 | ||
8410 | is printed. The | |
8411 | <B>-v</B> | |
8412 | ||
8413 | option causes a single word indicating the command or file name | |
8414 | used to invoke | |
8415 | <I>command</I> | |
8416 | ||
8417 | to be displayed; the | |
8418 | <B>-V</B> | |
8419 | ||
8420 | option produces a more verbose description. | |
8421 | If the | |
8422 | <B>-V</B> | |
8423 | ||
8424 | or | |
8425 | <B>-v</B> | |
8426 | ||
8427 | option is supplied, the exit status is 0 if | |
8428 | <I>command</I> | |
8429 | ||
8430 | was found, and 1 if not. If neither option is supplied and | |
8431 | an error occurred or | |
8432 | <I>command</I> | |
8433 | ||
8434 | cannot be found, the exit status is 127. Otherwise, the exit status of the | |
8435 | <B>command</B> | |
8436 | ||
8437 | builtin is the exit status of | |
8438 | <I>command</I>. | |
8439 | ||
8440 | <DT><B>compgen</B> [<I>option</I>] [<I>word</I>]<DD> | |
8441 | Generate possible completion matches for <I>word</I> according to | |
8442 | the <I>option</I>s, which may be any option accepted by the | |
8443 | <B>complete</B> | |
8444 | ||
8445 | builtin with the exception of <B>-p</B> and <B>-r</B>, and write | |
8446 | the matches to the standard output. | |
8447 | When using the <B>-F</B> or <B>-C</B> options, the various shell variables | |
8448 | set by the programmable completion facilities, while available, will not | |
8449 | have useful values. | |
8450 | <P> | |
8451 | The matches will be generated in the same way as if the programmable | |
8452 | completion code had generated them directly from a completion specification | |
8453 | with the same flags. | |
8454 | If <I>word</I> is specified, only those completions matching <I>word</I> | |
8455 | will be displayed. | |
8456 | <P> | |
8457 | The return value is true unless an invalid option is supplied, or no | |
8458 | matches were generated. | |
8459 | <DT><B>complete</B> [<B>-abcdefgjksuv</B>] [<B>-o</B> <I>comp-option</I>] [<B>-E</B>] [<B>-A</B> <I>action</I>] [<B>-G</B> <I>globpat</I>] [<B>-W</B> <I>wordlist</I>] [<B>-F</B> <I>function</I>] [<B>-C</B> <I>command</I>]<DD> | |
8460 | <BR> | |
8461 | ||
8462 | [<B>-X</B> <I>filterpat</I>] [<B>-P</B> <I>prefix</I>] [<B>-S</B> <I>suffix</I>] <I>name</I> [<I>name ...</I>] | |
8463 | ||
8464 | <DT><B>complete</B> <B>-pr</B> [<B>-E</B>] [<I>name</I> ...]<DD> | |
8465 | ||
8466 | Specify how arguments to each <I>name</I> should be completed. | |
8467 | If the <B>-p</B> option is supplied, or if no options are supplied, | |
8468 | existing completion specifications are printed in a way that allows | |
8469 | them to be reused as input. | |
8470 | The <B>-r</B> option removes a completion specification for | |
8471 | each <I>name</I>, or, if no <I>name</I>s are supplied, all | |
8472 | completion specifications. | |
8473 | The <B>-E</B> option indicates that the remaining options and actions should | |
8474 | apply to ``empty'' command completion; that is, completion attempted on a | |
8475 | blank line. | |
8476 | <P> | |
8477 | The process of applying these completion specifications when word completion | |
8478 | is attempted is described above under <B>Programmable Completion</B>. | |
8479 | <P> | |
8480 | Other options, if specified, have the following meanings. | |
8481 | The arguments to the <B>-G</B>, <B>-W</B>, and <B>-X</B> options | |
8482 | (and, if necessary, the <B>-P</B> and <B>-S</B> options) | |
8483 | should be quoted to protect them from expansion before the | |
8484 | <B>complete</B> | |
8485 | ||
8486 | builtin is invoked. | |
8487 | <DL COMPACT><DT><DD> | |
8488 | ||
8489 | <DL COMPACT> | |
8490 | <DT><B>-o</B> <I>comp-option</I><DD> | |
8491 | The <I>comp-option</I> controls several aspects of the compspec's behavior | |
8492 | beyond the simple generation of completions. | |
8493 | <I>comp-option</I> may be one of: | |
8494 | <DL COMPACT><DT><DD> | |
8495 | <DL COMPACT> | |
8496 | <DT><B>bashdefault</B> | |
8497 | ||
8498 | <DD> | |
8499 | Perform the rest of the default <B>bash</B> completions if the compspec | |
8500 | generates no matches. | |
8501 | <DT><B>default</B> | |
8502 | ||
8503 | <DD> | |
8504 | Use readline's default filename completion if the compspec generates | |
8505 | no matches. | |
8506 | <DT><B>dirnames</B> | |
8507 | ||
8508 | <DD> | |
8509 | Perform directory name completion if the compspec generates no matches. | |
8510 | <DT><B>filenames</B> | |
8511 | ||
8512 | <DD> | |
8513 | Tell readline that the compspec generates filenames, so it can perform any | |
8514 | filename-specific processing (like adding a slash to directory names, | |
8515 | quoting special characters, or suppressing trailing spaces). | |
8516 | Intended to be used with shell functions. | |
8517 | <DT><B>nospace</B> | |
8518 | ||
8519 | <DD> | |
8520 | Tell readline not to append a space (the default) to words completed at | |
8521 | the end of the line. | |
8522 | <DT><B>plusdirs</B> | |
8523 | ||
8524 | <DD> | |
8525 | After any matches defined by the compspec are generated, | |
8526 | directory name completion is attempted and any | |
8527 | matches are added to the results of the other actions. | |
8528 | </DL></DL> | |
8529 | ||
8530 | <DT><B>-A</B> <I>action</I><DD> | |
8531 | The <I>action</I> may be one of the following to generate a list of possible | |
8532 | completions: | |
8533 | <DL COMPACT><DT><DD> | |
8534 | <DL COMPACT> | |
8535 | <DT><B>alias</B> | |
8536 | ||
8537 | <DD> | |
8538 | Alias names. May also be specified as <B>-a</B>. | |
8539 | <DT><B>arrayvar</B> | |
8540 | ||
8541 | <DD> | |
8542 | Array variable names. | |
8543 | <DT><B>binding</B> | |
8544 | ||
8545 | <DD> | |
8546 | <B>Readline</B> key binding names. | |
8547 | <DT><B>builtin</B> | |
8548 | ||
8549 | <DD> | |
8550 | Names of shell builtin commands. May also be specified as <B>-b</B>. | |
8551 | <DT><B>command</B> | |
8552 | ||
8553 | <DD> | |
8554 | Command names. May also be specified as <B>-c</B>. | |
8555 | <DT><B>directory</B> | |
8556 | ||
8557 | <DD> | |
8558 | Directory names. May also be specified as <B>-d</B>. | |
8559 | <DT><B>disabled</B> | |
8560 | ||
8561 | <DD> | |
8562 | Names of disabled shell builtins. | |
8563 | <DT><B>enabled</B> | |
8564 | ||
8565 | <DD> | |
8566 | Names of enabled shell builtins. | |
8567 | <DT><B>export</B> | |
8568 | ||
8569 | <DD> | |
8570 | Names of exported shell variables. May also be specified as <B>-e</B>. | |
8571 | <DT><B>file</B> | |
8572 | ||
8573 | <DD> | |
8574 | File names. May also be specified as <B>-f</B>. | |
8575 | <DT><B>function</B> | |
8576 | ||
8577 | <DD> | |
8578 | Names of shell functions. | |
8579 | <DT><B>group</B> | |
8580 | ||
8581 | <DD> | |
8582 | Group names. May also be specified as <B>-g</B>. | |
8583 | <DT><B>helptopic</B> | |
8584 | ||
8585 | <DD> | |
8586 | Help topics as accepted by the <B>help</B> builtin. | |
8587 | <DT><B>hostname</B> | |
8588 | ||
8589 | <DD> | |
8590 | Hostnames, as taken from the file specified by the | |
8591 | <FONT SIZE=-1><B>HOSTFILE</B> | |
8592 | ||
8593 | </FONT> | |
8594 | shell variable. | |
8595 | <DT><B>job</B> | |
8596 | ||
8597 | <DD> | |
8598 | Job names, if job control is active. May also be specified as <B>-j</B>. | |
8599 | <DT><B>keyword</B> | |
8600 | ||
8601 | <DD> | |
8602 | Shell reserved words. May also be specified as <B>-k</B>. | |
8603 | <DT><B>running</B> | |
8604 | ||
8605 | <DD> | |
8606 | Names of running jobs, if job control is active. | |
8607 | <DT><B>service</B> | |
8608 | ||
8609 | <DD> | |
8610 | Service names. May also be specified as <B>-s</B>. | |
8611 | <DT><B>setopt</B> | |
8612 | ||
8613 | <DD> | |
8614 | Valid arguments for the <B>-o</B> option to the <B>set</B> builtin. | |
8615 | <DT><B>shopt</B> | |
8616 | ||
8617 | <DD> | |
8618 | Shell option names as accepted by the <B>shopt</B> builtin. | |
8619 | <DT><B>signal</B> | |
8620 | ||
8621 | <DD> | |
8622 | Signal names. | |
8623 | <DT><B>stopped</B> | |
8624 | ||
8625 | <DD> | |
8626 | Names of stopped jobs, if job control is active. | |
8627 | <DT><B>user</B> | |
8628 | ||
8629 | <DD> | |
8630 | User names. May also be specified as <B>-u</B>. | |
8631 | <DT><B>variable</B> | |
8632 | ||
8633 | <DD> | |
8634 | Names of all shell variables. May also be specified as <B>-v</B>. | |
8635 | </DL></DL> | |
8636 | ||
8637 | <DT><B>-G</B> <I>globpat</I><DD> | |
8638 | The filename expansion pattern <I>globpat</I> is expanded to generate | |
8639 | the possible completions. | |
8640 | <DT><B>-W</B> <I>wordlist</I><DD> | |
8641 | The <I>wordlist</I> is split using the characters in the | |
8642 | <FONT SIZE=-1><B>IFS</B> | |
8643 | ||
8644 | </FONT> | |
8645 | special variable as delimiters, and each resultant word is expanded. | |
8646 | The possible completions are the members of the resultant list which | |
8647 | match the word being completed. | |
8648 | <DT><B>-C</B> <I>command</I><DD> | |
8649 | <I>command</I> is executed in a subshell environment, and its output is | |
8650 | used as the possible completions. | |
8651 | <DT><B>-F</B> <I>function</I><DD> | |
8652 | The shell function <I>function</I> is executed in the current shell | |
8653 | environment. | |
8654 | When it finishes, the possible completions are retrieved from the value | |
8655 | of the | |
8656 | <FONT SIZE=-1><B>COMPREPLY</B> | |
8657 | ||
8658 | </FONT> | |
8659 | array variable. | |
8660 | <DT><B>-X</B> <I>filterpat</I><DD> | |
8661 | <I>filterpat</I> is a pattern as used for filename expansion. | |
8662 | It is applied to the list of possible completions generated by the | |
8663 | preceding options and arguments, and each completion matching | |
8664 | <I>filterpat</I> is removed from the list. | |
8665 | A leading <B>!</B> in <I>filterpat</I> negates the pattern; in this | |
8666 | case, any completion not matching <I>filterpat</I> is removed. | |
8667 | <DT><B>-P</B> <I>prefix</I><DD> | |
8668 | <I>prefix</I> is added at the beginning of each possible completion | |
8669 | after all other options have been applied. | |
8670 | <DT><B>-S</B> <I>suffix</I><DD> | |
8671 | <I>suffix</I> is appended to each possible completion | |
8672 | after all other options have been applied. | |
8673 | ||
8674 | </DL> | |
8675 | <P> | |
8676 | ||
8677 | The return value is true unless an invalid option is supplied, an option | |
8678 | other than <B>-p</B> or <B>-r</B> is supplied without a <I>name</I> | |
8679 | argument, an attempt is made to remove a completion specification for | |
8680 | a <I>name</I> for which no specification exists, or | |
8681 | an error occurs adding a completion specification. | |
8682 | </DL> | |
8683 | ||
8684 | <DT><B>compopt</B> [<B>-o</B> <I>option</I>] [<B>+o</B> <I>option</I>] [<I>name</I>]<DD> | |
8685 | Modify completion options for each <I>name</I> according to the | |
8686 | <I>option</I>s, or for the | |
8687 | currently-execution completion if no <I>name</I>s are supplied. | |
8688 | If no <I>option</I>s are given, display the completion options for each | |
8689 | <I>name</I> or the current completion. | |
8690 | The possible values of <I>option</I> are those valid for the <B>complete</B> | |
8691 | builtin described above. | |
8692 | </DL> | |
8693 | <P> | |
8694 | ||
8695 | The return value is true unless an invalid option is supplied, an attempt | |
8696 | is made to modify the options for a <I>name</I> for which no completion | |
8697 | specification exists, or an output error occurs. | |
8698 | <DL COMPACT> | |
8699 | <DT><B>continue</B> [<I>n</I>]<DD> | |
8700 | Resume the next iteration of the enclosing | |
8701 | <B>for</B>, | |
8702 | ||
8703 | <B>while</B>, | |
8704 | ||
8705 | <B>until</B>, | |
8706 | ||
8707 | or | |
8708 | <B>select</B> | |
8709 | ||
8710 | loop. | |
8711 | If | |
8712 | <I>n</I> | |
8713 | ||
8714 | is specified, resume at the <I>n</I>th enclosing loop. | |
8715 | <I>n</I> | |
8716 | ||
8717 | must be >= 1. If | |
8718 | <I>n</I> | |
8719 | ||
8720 | is greater than the number of enclosing loops, the last enclosing loop | |
8721 | (the ``top-level'' loop) is resumed. | |
8722 | The return value is 0 unless <I>n</I> is not greater than or equal to 1. | |
8723 | <DT><B>declare</B> [<B>-aAfFilrtux</B>] [<B>-p</B>] [<I>name</I>[=<I>value</I>] ...]<DD> | |
8724 | ||
8725 | <DT><B>typeset</B> [<B>-aAfFilrtux</B>] [<B>-p</B>] [<I>name</I>[=<I>value</I>] ...]<DD> | |
8726 | ||
8727 | Declare variables and/or give them attributes. | |
8728 | If no <I>name</I>s are given then display the values of variables. | |
8729 | The | |
8730 | <B>-p</B> | |
8731 | ||
8732 | option will display the attributes and values of each | |
8733 | <I>name</I>. | |
8734 | ||
8735 | When | |
8736 | <B>-p</B> | |
8737 | ||
8738 | is used with <I>name</I> arguments, additional options are ignored. | |
8739 | When | |
8740 | <B>-p</B> | |
8741 | ||
8742 | is supplied without <I>name</I> arguments, it will display the attributes | |
8743 | and values of all variables having the attributes specified by the | |
8744 | additional options. | |
8745 | If no other options are supplied with <B>-p</B>, <B>declare</B> will display | |
8746 | the attributes and values of all shell variables. The <B>-f</B> option | |
8747 | will restrict the display to shell functions. | |
8748 | The | |
8749 | <B>-F</B> | |
8750 | ||
8751 | option inhibits the display of function definitions; only the | |
8752 | function name and attributes are printed. | |
8753 | If the <B>extdebug</B> shell option is enabled using <B>shopt</B>, | |
8754 | the source file name and line number where the function is defined | |
8755 | are displayed as well. The | |
8756 | <B>-F</B> | |
8757 | ||
8758 | option implies | |
8759 | <B>-f</B>. | |
8760 | ||
8761 | The following options can | |
8762 | be used to restrict output to variables with the specified attribute or | |
8763 | to give variables attributes: | |
8764 | <DL COMPACT><DT><DD> | |
8765 | ||
8766 | <DL COMPACT> | |
8767 | <DT><B>-a</B> | |
8768 | ||
8769 | <DD> | |
8770 | Each <I>name</I> is an indexed array variable (see | |
8771 | <B>Arrays</B> | |
8772 | ||
8773 | above). | |
8774 | <DT><B>-A</B> | |
8775 | ||
8776 | <DD> | |
8777 | Each <I>name</I> is an associative array variable (see | |
8778 | <B>Arrays</B> | |
8779 | ||
8780 | above). | |
8781 | <DT><B>-f</B> | |
8782 | ||
8783 | <DD> | |
8784 | Use function names only. | |
8785 | <DT><B>-i</B> | |
8786 | ||
8787 | <DD> | |
8788 | The variable is treated as an integer; arithmetic evaluation (see | |
8789 | <FONT SIZE=-1><B>ARITHMETIC EVALUATION ) </B> | |
8790 | ||
8791 | </FONT> | |
8792 | is performed when the variable is assigned a value. | |
8793 | <DT><B>-l</B> | |
8794 | ||
8795 | <DD> | |
8796 | When the variable is assigned a value, all upper-case characters are | |
8797 | converted to lower-case. | |
8798 | The upper-case attribute is disabled. | |
8799 | <DT><B>-r</B> | |
8800 | ||
8801 | <DD> | |
8802 | Make <I>name</I>s readonly. These names cannot then be assigned values | |
8803 | by subsequent assignment statements or unset. | |
8804 | <DT><B>-t</B> | |
8805 | ||
8806 | <DD> | |
8807 | Give each <I>name</I> the <I>trace</I> attribute. | |
8808 | Traced functions inherit the <B>DEBUG</B> and <B>RETURN</B> traps from | |
8809 | the calling shell. | |
8810 | The trace attribute has no special meaning for variables. | |
8811 | <DT><B>-u</B> | |
8812 | ||
8813 | <DD> | |
8814 | When the variable is assigned a value, all lower-case characters are | |
8815 | converted to upper-case. | |
8816 | The lower-case attribute is disabled. | |
8817 | <DT><B>-x</B> | |
8818 | ||
8819 | <DD> | |
8820 | Mark <I>name</I>s for export to subsequent commands via the environment. | |
8821 | ||
8822 | </DL> | |
8823 | <P> | |
8824 | ||
8825 | Using `+' instead of `-' | |
8826 | turns off the attribute instead, | |
8827 | with the exceptions that <B>+a</B> | |
8828 | may not be used to destroy an array variable and <B>+r will not | |
8829 | remove the readonly attribute. | |
8830 | When used in a function, | |
8831 | makes each | |
8832 | </B><I>name</I> local, as with the | |
8833 | <B>local</B> | |
8834 | ||
8835 | command. | |
8836 | If a variable name is followed by =<I>value</I>, the value of | |
8837 | the variable is set to <I>value</I>. | |
8838 | The return value is 0 unless an invalid option is encountered, | |
8839 | an attempt is made to define a function using | |
8840 | ||
8841 | <TT>-f foo=bar</TT>, | |
8842 | an attempt is made to assign a value to a readonly variable, | |
8843 | an attempt is made to assign a value to an array variable without | |
8844 | using the compound assignment syntax (see | |
8845 | <B>Arrays</B> | |
8846 | ||
8847 | above), one of the <I>names</I> is not a valid shell variable name, | |
8848 | an attempt is made to turn off readonly status for a readonly variable, | |
8849 | an attempt is made to turn off array status for an array variable, | |
8850 | or an attempt is made to display a non-existent function with <B>-f</B>. | |
8851 | </DL> | |
8852 | ||
8853 | <DT><B>dirs [+</B><I>n</I>] [-<I>n</I>] [<B>-cplv</B>] | |
8854 | ||
8855 | <DD> | |
8856 | Without options, displays the list of currently remembered directories. | |
8857 | The default display is on a single line with directory names separated | |
8858 | by spaces. | |
8859 | Directories are added to the list with the | |
8860 | <B>pushd</B> | |
8861 | ||
8862 | command; the | |
8863 | <B>popd</B> | |
8864 | ||
8865 | command removes entries from the list. | |
8866 | <DL COMPACT><DT><DD> | |
8867 | ||
8868 | <DL COMPACT> | |
8869 | <DT><B>+</B><I>n</I><DD> | |
8870 | Displays the <I>n</I>th entry counting from the left of the list | |
8871 | shown by | |
8872 | <B>dirs</B> | |
8873 | ||
8874 | when invoked without options, starting with zero. | |
8875 | <DT><B>-</B><I>n</I><DD> | |
8876 | Displays the <I>n</I>th entry counting from the right of the list | |
8877 | shown by | |
8878 | <B>dirs</B> | |
8879 | ||
8880 | when invoked without options, starting with zero. | |
8881 | <DT><B>-c</B> | |
8882 | ||
8883 | <DD> | |
8884 | Clears the directory stack by deleting all of the entries. | |
8885 | <DT><B>-l</B> | |
8886 | ||
8887 | <DD> | |
8888 | Produces a longer listing; the default listing format uses a | |
8889 | tilde to denote the home directory. | |
8890 | <DT><B>-p</B> | |
8891 | ||
8892 | <DD> | |
8893 | Print the directory stack with one entry per line. | |
8894 | <DT><B>-v</B> | |
8895 | ||
8896 | <DD> | |
8897 | Print the directory stack with one entry per line, | |
8898 | prefixing each entry with its index in the stack. | |
8899 | ||
8900 | </DL> | |
8901 | <P> | |
8902 | ||
8903 | The return value is 0 unless an | |
8904 | invalid option is supplied or <I>n</I> indexes beyond the end | |
8905 | of the directory stack. | |
8906 | </DL> | |
8907 | ||
8908 | <DT><B>disown</B> [<B>-ar</B>] [<B>-h</B>] [<I>jobspec</I> ...]<DD> | |
8909 | Without options, each | |
8910 | <I>jobspec</I> | |
8911 | ||
8912 | is removed from the table of active jobs. | |
8913 | If | |
8914 | <I>jobspec</I> | |
8915 | ||
8916 | is not present, and neither <B>-a nor -r</B> is supplied, | |
8917 | the shell's notion of the <I>current job</I> is used. | |
8918 | If the <B>-h</B> option is given, each | |
8919 | <I>jobspec</I> | |
8920 | ||
8921 | is not removed from the table, but is marked so that | |
8922 | <FONT SIZE=-1><B>SIGHUP</B> | |
8923 | ||
8924 | </FONT> | |
8925 | is not sent to the job if the shell receives a | |
8926 | <FONT SIZE=-1><B>SIGHUP</B>. | |
8927 | ||
8928 | </FONT> | |
8929 | If no | |
8930 | <I>jobspec</I> | |
8931 | ||
8932 | is present, and neither the | |
8933 | <B>-a</B> | |
8934 | ||
8935 | nor the | |
8936 | <B>-r</B> | |
8937 | ||
8938 | option is supplied, the <I>current job</I> is used. | |
8939 | If no | |
8940 | <I>jobspec</I> | |
8941 | ||
8942 | is supplied, the | |
8943 | <B>-a</B> | |
8944 | ||
8945 | option means to remove or mark all jobs; the | |
8946 | <B>-r</B> | |
8947 | ||
8948 | option without a | |
8949 | <I>jobspec</I> | |
8950 | ||
8951 | argument restricts operation to running jobs. | |
8952 | The return value is 0 unless a | |
8953 | <I>jobspec</I> | |
8954 | ||
8955 | does not specify a valid job. | |
8956 | <DT><B>echo</B> [<B>-neE</B>] [<I>arg</I> ...]<DD> | |
8957 | Output the <I>arg</I>s, separated by spaces, followed by a newline. | |
8958 | The return status is always 0. | |
8959 | If <B>-n</B> is specified, the trailing newline is | |
8960 | suppressed. If the <B>-e</B> option is given, interpretation of | |
8961 | the following backslash-escaped characters is enabled. The | |
8962 | <B>-E</B> | |
8963 | ||
8964 | option disables the interpretation of these escape characters, | |
8965 | even on systems where they are interpreted by default. | |
8966 | The <B>xpg_echo</B> shell option may be used to | |
8967 | dynamically determine whether or not <B>echo</B> expands these | |
8968 | escape characters by default. | |
8969 | <B>echo</B> | |
8970 | ||
8971 | does not interpret <B>--</B> to mean the end of options. | |
8972 | <B>echo</B> | |
8973 | ||
8974 | interprets the following escape sequences: | |
8975 | <DL COMPACT><DT><DD> | |
8976 | ||
8977 | <DL COMPACT> | |
8978 | <DT><B>\a</B> | |
8979 | ||
8980 | <DD> | |
8981 | alert (bell) | |
8982 | <DT><B>\b</B> | |
8983 | ||
8984 | <DD> | |
8985 | backspace | |
8986 | <DT><B>\c</B> | |
8987 | ||
8988 | <DD> | |
8989 | suppress further output | |
8990 | <DT><B>\e</B> | |
8991 | ||
8992 | <DD> | |
8993 | an escape character | |
8994 | <DT><B>\f</B> | |
8995 | ||
8996 | <DD> | |
8997 | form feed | |
8998 | <DT><B>\n</B> | |
8999 | ||
9000 | <DD> | |
9001 | new line | |
9002 | <DT><B>\r</B> | |
9003 | ||
9004 | <DD> | |
9005 | carriage return | |
9006 | <DT><B>\t</B> | |
9007 | ||
9008 | <DD> | |
9009 | horizontal tab | |
9010 | <DT><B>\v</B> | |
9011 | ||
9012 | <DD> | |
9013 | vertical tab | |
9014 | <DT><B>\\</B> | |
9015 | ||
9016 | <DD> | |
9017 | backslash | |
9018 | <DT><B>\0</B><I>nnn</I> | |
9019 | ||
9020 | <DD> | |
9021 | the eight-bit character whose value is the octal value <I>nnn</I> | |
9022 | (zero to three octal digits) | |
9023 | <DT><B>\x</B><I>HH</I> | |
9024 | ||
9025 | <DD> | |
9026 | the eight-bit character whose value is the hexadecimal value <I>HH</I> | |
9027 | (one or two hex digits) | |
9028 | ||
9029 | </DL></DL> | |
9030 | ||
9031 | <DT><B>enable</B> [<B>-a</B>] [<B>-dnps</B>] [<B>-f</B> <I>filename</I>] [<I>name</I> ...]<DD> | |
9032 | Enable and disable builtin shell commands. | |
9033 | Disabling a builtin allows a disk command which has the same name | |
9034 | as a shell builtin to be executed without specifying a full pathname, | |
9035 | even though the shell normally searches for builtins before disk commands. | |
9036 | If <B>-n</B> is used, each <I>name</I> | |
9037 | is disabled; otherwise, | |
9038 | <I>names</I> are enabled. For example, to use the | |
9039 | <B>test</B> | |
9040 | ||
9041 | binary found via the | |
9042 | <FONT SIZE=-1><B>PATH</B> | |
9043 | ||
9044 | </FONT> | |
9045 | instead of the shell builtin version, run | |
9046 | <TT>enable -n test</TT>. | |
9047 | ||
9048 | The | |
9049 | <B>-f</B> | |
9050 | ||
9051 | option means to load the new builtin command | |
9052 | <I>name</I> | |
9053 | ||
9054 | from shared object | |
9055 | <I>filename</I>, | |
9056 | ||
9057 | on systems that support dynamic loading. The | |
9058 | <B>-d</B> | |
9059 | ||
9060 | option will delete a builtin previously loaded with | |
9061 | <B>-f</B>. | |
9062 | ||
9063 | If no <I>name</I> arguments are given, or if the | |
9064 | <B>-p</B> | |
9065 | ||
9066 | option is supplied, a list of shell builtins is printed. | |
9067 | With no other option arguments, the list consists of all enabled | |
9068 | shell builtins. | |
9069 | If <B>-n</B> is supplied, only disabled builtins are printed. | |
9070 | If <B>-a</B> is supplied, the list printed includes all builtins, with an | |
9071 | indication of whether or not each is enabled. | |
9072 | If <B>-s</B> is supplied, the output is restricted to the POSIX | |
9073 | <I>special</I> builtins. | |
9074 | The return value is 0 unless a | |
9075 | <I>name</I> | |
9076 | ||
9077 | is not a shell builtin or there is an error loading a new builtin | |
9078 | from a shared object. | |
9079 | <DT><B>eval</B> [<I>arg</I> ...]<DD> | |
9080 | The <I>arg</I>s are read and concatenated together into a single | |
9081 | command. This command is then read and executed by the shell, and | |
9082 | its exit status is returned as the value of | |
9083 | <B>eval</B>. | |
9084 | ||
9085 | If there are no | |
9086 | <I>args</I>, | |
9087 | ||
9088 | or only null arguments, | |
9089 | <B>eval</B> | |
9090 | ||
9091 | returns 0. | |
9092 | <DT><B>exec</B> [<B>-cl</B>] [<B>-a</B> <I>name</I>] [<I>command</I> [<I>arguments</I>]]<DD> | |
9093 | If | |
9094 | <I>command</I> | |
9095 | ||
9096 | is specified, it replaces the shell. | |
9097 | No new process is created. The | |
9098 | <I>arguments</I> | |
9099 | ||
9100 | become the arguments to <I>command</I>. | |
9101 | If the | |
9102 | <B>-l</B> | |
9103 | ||
9104 | option is supplied, | |
9105 | the shell places a dash at the beginning of the zeroth argument passed to | |
9106 | <I>command</I>. | |
9107 | ||
9108 | This is what | |
9109 | <I>login</I>(1) | |
9110 | ||
9111 | does. The | |
9112 | <B>-c</B> | |
9113 | ||
9114 | option causes | |
9115 | <I>command</I> | |
9116 | ||
9117 | to be executed with an empty environment. If | |
9118 | <B>-a</B> | |
9119 | ||
9120 | is supplied, the shell passes | |
9121 | <I>name</I> | |
9122 | ||
9123 | as the zeroth argument to the executed command. If | |
9124 | <I>command</I> | |
9125 | ||
9126 | cannot be executed for some reason, a non-interactive shell exits, | |
9127 | unless the shell option | |
9128 | <B>execfail</B> | |
9129 | ||
9130 | is enabled, in which case it returns failure. | |
9131 | An interactive shell returns failure if the file cannot be executed. | |
9132 | If | |
9133 | <I>command</I> | |
9134 | ||
9135 | is not specified, any redirections take effect in the current shell, | |
9136 | and the return status is 0. If there is a redirection error, the | |
9137 | return status is 1. | |
9138 | <DT><B>exit</B> [<I>n</I>]<DD> | |
9139 | Cause the shell to exit | |
9140 | with a status of <I>n</I>. If | |
9141 | <I>n</I> | |
9142 | ||
9143 | is omitted, the exit status | |
9144 | is that of the last command executed. | |
9145 | A trap on | |
9146 | <FONT SIZE=-1><B>EXIT</B> | |
9147 | ||
9148 | </FONT> | |
9149 | is executed before the shell terminates. | |
9150 | <DT><B>export</B> [<B>-fn</B>] [<I>name</I>[=<I>word</I>]] ...<DD> | |
9151 | ||
9152 | <DT><B>export -p</B> | |
9153 | ||
9154 | <DD> | |
9155 | ||
9156 | The supplied | |
9157 | <I>names</I> | |
9158 | ||
9159 | are marked for automatic export to the environment of | |
9160 | subsequently executed commands. If the | |
9161 | <B>-f</B> | |
9162 | ||
9163 | option is given, | |
9164 | the | |
9165 | <I>names</I> | |
9166 | ||
9167 | refer to functions. | |
9168 | If no | |
9169 | <I>names</I> | |
9170 | ||
9171 | are given, or if the | |
9172 | <B>-p</B> | |
9173 | ||
9174 | option is supplied, a list | |
9175 | of all names that are exported in this shell is printed. | |
9176 | The | |
9177 | <B>-n</B> | |
9178 | ||
9179 | option causes the export property to be removed from each | |
9180 | <I>name</I>. | |
9181 | If a variable name is followed by =<I>word</I>, the value of | |
9182 | the variable is set to <I>word</I>. | |
9183 | <B>export</B> | |
9184 | ||
9185 | returns an exit status of 0 unless an invalid option is | |
9186 | encountered, | |
9187 | one of the <I>names</I> is not a valid shell variable name, or | |
9188 | <B>-f</B> | |
9189 | ||
9190 | is supplied with a | |
9191 | <I>name</I> | |
9192 | ||
9193 | that is not a function. | |
9194 | <DT><B>fc</B> [<B>-e</B> <I>ename</I>] [<B>-lnr</B>] [<I>first</I>] [<I>last</I>]<DD> | |
9195 | ||
9196 | <DT><B>fc</B> <B>-s</B> [<I>pat</I>=<I>rep</I>] [<I>cmd</I>]<DD> | |
9197 | ||
9198 | Fix Command. In the first form, a range of commands from | |
9199 | <I>first</I> | |
9200 | ||
9201 | to | |
9202 | <I>last</I> | |
9203 | ||
9204 | is selected from the history list. | |
9205 | <I>First</I> | |
9206 | ||
9207 | and | |
9208 | <I>last</I> | |
9209 | ||
9210 | may be specified as a string (to locate the last command beginning | |
9211 | with that string) or as a number (an index into the history list, | |
9212 | where a negative number is used as an offset from the current | |
9213 | command number). If | |
9214 | <I>last</I> | |
9215 | ||
9216 | is not specified it is set to | |
9217 | the current command for listing (so that | |
9218 | ||
9219 | <TT>fc -l -10</TT> | |
9220 | prints the last 10 commands) and to | |
9221 | <I>first</I> | |
9222 | ||
9223 | otherwise. | |
9224 | If | |
9225 | <I>first</I> | |
9226 | ||
9227 | is not specified it is set to the previous | |
9228 | command for editing and -16 for listing. | |
9229 | <P> | |
9230 | The | |
9231 | <B>-n</B> | |
9232 | ||
9233 | option suppresses | |
9234 | the command numbers when listing. The | |
9235 | <B>-r</B> | |
9236 | ||
9237 | option reverses the order of | |
9238 | the commands. If the | |
9239 | <B>-l</B> | |
9240 | ||
9241 | option is given, | |
9242 | the commands are listed on | |
9243 | standard output. Otherwise, the editor given by | |
9244 | <I>ename</I> | |
9245 | ||
9246 | is invoked | |
9247 | on a file containing those commands. If | |
9248 | <I>ename</I> | |
9249 | ||
9250 | is not given, the | |
9251 | value of the | |
9252 | <FONT SIZE=-1><B>FCEDIT</B> | |
9253 | ||
9254 | </FONT> | |
9255 | variable is used, and | |
9256 | the value of | |
9257 | <FONT SIZE=-1><B>EDITOR</B> | |
9258 | ||
9259 | </FONT> | |
9260 | if | |
9261 | <FONT SIZE=-1><B>FCEDIT</B> | |
9262 | ||
9263 | </FONT> | |
9264 | is not set. If neither variable is set, | |
9265 | ||
9266 | <I>vi</I> | |
9267 | ||
9268 | is used. When editing is complete, the edited commands are | |
9269 | echoed and executed. | |
9270 | <P> | |
9271 | In the second form, <I>command</I> is re-executed after each instance | |
9272 | of <I>pat</I> is replaced by <I>rep</I>. | |
9273 | A useful alias to use with this is | |
9274 | ||
9275 | <TT>r='fc -s'</TT>, | |
9276 | so that typing | |
9277 | ||
9278 | <TT>r cc</TT> | |
9279 | runs the last command beginning with | |
9280 | ||
9281 | <TT>cc</TT> | |
9282 | and typing | |
9283 | ||
9284 | <TT>r</TT> | |
9285 | re-executes the last command. | |
9286 | <P> | |
9287 | If the first form is used, the return value is 0 unless an invalid | |
9288 | option is encountered or | |
9289 | <I>first</I> | |
9290 | ||
9291 | or | |
9292 | <I>last</I> | |
9293 | ||
9294 | specify history lines out of range. | |
9295 | If the | |
9296 | <B>-e</B> | |
9297 | ||
9298 | option is supplied, the return value is the value of the last | |
9299 | command executed or failure if an error occurs with the temporary | |
9300 | file of commands. If the second form is used, the return status | |
9301 | is that of the command re-executed, unless | |
9302 | <I>cmd</I> | |
9303 | ||
9304 | does not specify a valid history line, in which case | |
9305 | <B>fc</B> | |
9306 | ||
9307 | returns failure. | |
9308 | <DT><B>fg</B> [<I>jobspec</I>]<DD> | |
9309 | Resume | |
9310 | <I>jobspec</I> | |
9311 | ||
9312 | in the foreground, and make it the current job. | |
9313 | If | |
9314 | <I>jobspec</I> | |
9315 | ||
9316 | is not present, the shell's notion of the <I>current job</I> is used. | |
9317 | The return value is that of the command placed into the foreground, | |
9318 | or failure if run when job control is disabled or, when run with | |
9319 | job control enabled, if | |
9320 | <I>jobspec</I> | |
9321 | ||
9322 | does not specify a valid job or | |
9323 | <I>jobspec</I> | |
9324 | ||
9325 | specifies a job that was started without job control. | |
9326 | <DT><B>getopts</B> <I>optstring</I> <I>name</I> [<I>args</I>]<DD> | |
9327 | <B>getopts</B> | |
9328 | ||
9329 | is used by shell procedures to parse positional parameters. | |
9330 | <I>optstring</I> | |
9331 | ||
9332 | contains the option characters to be recognized; if a character | |
9333 | is followed by a colon, the option is expected to have an | |
9334 | argument, which should be separated from it by white space. | |
9335 | The colon and question mark characters may not be used as | |
9336 | option characters. | |
9337 | Each time it is invoked, | |
9338 | <B>getopts</B> | |
9339 | ||
9340 | places the next option in the shell variable | |
9341 | <I>name</I>, | |
9342 | ||
9343 | initializing | |
9344 | <I>name</I> | |
9345 | ||
9346 | if it does not exist, | |
9347 | and the index of the next argument to be processed into the | |
9348 | variable | |
9349 | <FONT SIZE=-1><B>OPTIND</B>. | |
9350 | ||
9351 | </FONT> | |
9352 | <FONT SIZE=-1><B>OPTIND</B> | |
9353 | ||
9354 | </FONT> | |
9355 | is initialized to 1 each time the shell or a shell script | |
9356 | is invoked. When an option requires an argument, | |
9357 | <B>getopts</B> | |
9358 | ||
9359 | places that argument into the variable | |
9360 | <FONT SIZE=-1><B>OPTARG</B>. | |
9361 | ||
9362 | </FONT> | |
9363 | The shell does not reset | |
9364 | <FONT SIZE=-1><B>OPTIND</B> | |
9365 | ||
9366 | </FONT> | |
9367 | automatically; it must be manually reset between multiple | |
9368 | calls to | |
9369 | <B>getopts</B> | |
9370 | ||
9371 | within the same shell invocation if a new set of parameters | |
9372 | is to be used. | |
9373 | <P> | |
9374 | When the end of options is encountered, <B>getopts</B> exits with a | |
9375 | return value greater than zero. | |
9376 | <B>OPTIND</B> is set to the index of the first non-option argument, | |
9377 | and <B>name</B> is set to ?. | |
9378 | <P> | |
9379 | <B>getopts</B> | |
9380 | ||
9381 | normally parses the positional parameters, but if more arguments are | |
9382 | given in | |
9383 | <I>args</I>, | |
9384 | ||
9385 | <B>getopts</B> | |
9386 | ||
9387 | parses those instead. | |
9388 | <P> | |
9389 | <B>getopts</B> | |
9390 | ||
9391 | can report errors in two ways. If the first character of | |
9392 | <I>optstring</I> | |
9393 | ||
9394 | is a colon, | |
9395 | <I>silent</I> | |
9396 | ||
9397 | error reporting is used. In normal operation diagnostic messages | |
9398 | are printed when invalid options or missing option arguments are | |
9399 | encountered. | |
9400 | If the variable | |
9401 | <FONT SIZE=-1><B>OPTERR</B> | |
9402 | ||
9403 | </FONT> | |
9404 | is set to 0, no error messages will be displayed, even if the first | |
9405 | character of | |
9406 | <I>optstring</I> | |
9407 | ||
9408 | is not a colon. | |
9409 | <P> | |
9410 | If an invalid option is seen, | |
9411 | <B>getopts</B> | |
9412 | ||
9413 | places ? into | |
9414 | <I>name</I> | |
9415 | ||
9416 | and, if not silent, | |
9417 | prints an error message and unsets | |
9418 | <FONT SIZE=-1><B>OPTARG</B>. | |
9419 | ||
9420 | </FONT> | |
9421 | If | |
9422 | <B>getopts</B> | |
9423 | ||
9424 | is silent, | |
9425 | the option character found is placed in | |
9426 | <FONT SIZE=-1><B>OPTARG</B> | |
9427 | ||
9428 | </FONT> | |
9429 | and no diagnostic message is printed. | |
9430 | <P> | |
9431 | If a required argument is not found, and | |
9432 | <B>getopts</B> | |
9433 | ||
9434 | is not silent, | |
9435 | a question mark (<B>?</B>) is placed in | |
9436 | <I>name</I>, | |
9437 | ||
9438 | <FONT SIZE=-1><B>OPTARG</B> | |
9439 | ||
9440 | </FONT> | |
9441 | is unset, and a diagnostic message is printed. | |
9442 | If | |
9443 | <B>getopts</B> | |
9444 | ||
9445 | is silent, then a colon (<B>:</B>) is placed in | |
9446 | <I>name</I> | |
9447 | ||
9448 | and | |
9449 | <FONT SIZE=-1><B>OPTARG</B> | |
9450 | ||
9451 | </FONT> | |
9452 | is set to the option character found. | |
9453 | <P> | |
9454 | <B>getopts</B> | |
9455 | ||
9456 | returns true if an option, specified or unspecified, is found. | |
9457 | It returns false if the end of options is encountered or an | |
9458 | error occurs. | |
9459 | <DT><B>hash</B> [<B>-lr</B>] [<B>-p</B> <I>filename</I>] [<B>-dt</B>] [<I>name</I>]<DD> | |
9460 | For each | |
9461 | <I>name</I>, | |
9462 | ||
9463 | the full file name of the command is determined by searching | |
9464 | the directories in | |
9465 | <B>$PATH</B> | |
9466 | ||
9467 | and remembered. | |
9468 | If the | |
9469 | <B>-p</B> | |
9470 | ||
9471 | option is supplied, no path search is performed, and | |
9472 | <I>filename</I> | |
9473 | ||
9474 | is used as the full file name of the command. | |
9475 | The | |
9476 | <B>-r</B> | |
9477 | ||
9478 | option causes the shell to forget all | |
9479 | remembered locations. | |
9480 | The | |
9481 | <B>-d</B> | |
9482 | ||
9483 | option causes the shell to forget the remembered location of each <I>name</I>. | |
9484 | If the | |
9485 | <B>-t</B> | |
9486 | ||
9487 | option is supplied, the full pathname to which each <I>name</I> corresponds | |
9488 | is printed. If multiple <I>name</I> arguments are supplied with <B>-t</B>, | |
9489 | the <I>name</I> is printed before the hashed full pathname. | |
9490 | The | |
9491 | <B>-l</B> | |
9492 | ||
9493 | option causes output to be displayed in a format that may be reused as input. | |
9494 | If no arguments are given, or if only <B>-l</B> is supplied, | |
9495 | information about remembered commands is printed. | |
9496 | The return status is true unless a | |
9497 | <I>name</I> | |
9498 | ||
9499 | is not found or an invalid option is supplied. | |
9500 | <DT><B>help</B> [<B>-dms</B>] [<I>pattern</I>]<DD> | |
9501 | Display helpful information about builtin commands. If | |
9502 | <I>pattern</I> | |
9503 | ||
9504 | is specified, | |
9505 | <B>help</B> | |
9506 | ||
9507 | gives detailed help on all commands matching | |
9508 | <I>pattern</I>; | |
9509 | ||
9510 | otherwise help for all the builtins and shell control structures | |
9511 | is printed. | |
9512 | <DL COMPACT><DT><DD> | |
9513 | ||
9514 | <DL COMPACT> | |
9515 | <DT><B>-d</B> | |
9516 | ||
9517 | <DD> | |
9518 | Display a short description of each <I>pattern</I> | |
9519 | <DT><B> -m</B> | |
9520 | ||
9521 | <DD> | |
9522 | Display the description of each <I>pattern</I> in a manpage-like format | |
9523 | <DT><B>-s</B> | |
9524 | ||
9525 | <DD> | |
9526 | Display only a short usage synopsis for each <I>pattern</I> | |
9527 | ||
9528 | </DL></DL> | |
9529 | ||
9530 | The return status is 0 unless no command matches | |
9531 | <I>pattern</I>. | |
9532 | ||
9533 | <DT><B>history [</B><I>n</I>]<DD> | |
9534 | ||
9535 | <DT><B>history</B> <B>-c</B><DD> | |
9536 | <DT><B>history -d</B> <I>offset</I><DD> | |
9537 | <DT><B>history</B> <B>-anrw</B> [<I>filename</I>]<DD> | |
9538 | <DT><B>history</B> <B>-p</B> <I>arg</I> [<I>arg ...</I>]<DD> | |
9539 | <DT><B>history</B> <B>-s</B> <I>arg</I> [<I>arg ...</I>]<DD> | |
9540 | ||
9541 | With no options, display the command | |
9542 | history list with line numbers. Lines listed | |
9543 | with a | |
9544 | <B>*</B> | |
9545 | ||
9546 | have been modified. An argument of | |
9547 | <I>n</I> | |
9548 | ||
9549 | lists only the last | |
9550 | <I>n</I> | |
9551 | ||
9552 | lines. | |
9553 | If the shell variable <B>HISTTIMEFORMAT</B> is set and not null, | |
9554 | it is used as a format string for <I>strftime</I>(3) to display | |
9555 | the time stamp associated with each displayed history entry. | |
9556 | No intervening blank is printed between the formatted time stamp | |
9557 | and the history line. | |
9558 | If <I>filename</I> is supplied, it is used as the | |
9559 | name of the history file; if not, the value of | |
9560 | <FONT SIZE=-1><B>HISTFILE</B> | |
9561 | ||
9562 | </FONT> | |
9563 | is used. Options, if supplied, have the following meanings: | |
9564 | <DL COMPACT><DT><DD> | |
9565 | ||
9566 | <DL COMPACT> | |
9567 | <DT><B>-c</B> | |
9568 | ||
9569 | <DD> | |
9570 | Clear the history list by deleting all the entries. | |
9571 | <DT><B>-d</B> <I>offset</I><DD> | |
9572 | Delete the history entry at position <I>offset</I>. | |
9573 | <DT><B>-a</B> | |
9574 | ||
9575 | <DD> | |
9576 | Append the ``new'' history lines (history lines entered since the | |
9577 | beginning of the current <B>bash</B> session) to the history file. | |
9578 | <DT><B>-n</B> | |
9579 | ||
9580 | <DD> | |
9581 | Read the history lines not already read from the history | |
9582 | file into the current history list. These are lines | |
9583 | appended to the history file since the beginning of the | |
9584 | current <B>bash</B> session. | |
9585 | <DT><B>-r</B> | |
9586 | ||
9587 | <DD> | |
9588 | Read the contents of the history file | |
9589 | and use them as the current history. | |
9590 | <DT><B>-w</B> | |
9591 | ||
9592 | <DD> | |
9593 | Write the current history to the history file, overwriting the | |
9594 | history file's contents. | |
9595 | <DT><B>-p</B> | |
9596 | ||
9597 | <DD> | |
9598 | Perform history substitution on the following <I>args</I> and display | |
9599 | the result on the standard output. | |
9600 | Does not store the results in the history list. | |
9601 | Each <I>arg</I> must be quoted to disable normal history expansion. | |
9602 | <DT><B>-s</B> | |
9603 | ||
9604 | <DD> | |
9605 | Store the | |
9606 | <I>args</I> | |
9607 | ||
9608 | in the history list as a single entry. The last command in the | |
9609 | history list is removed before the | |
9610 | <I>args</I> | |
9611 | ||
9612 | are added. | |
9613 | ||
9614 | </DL> | |
9615 | <P> | |
9616 | ||
9617 | If the <B>HISTTIMEFORMAT</B> is set, the time stamp information | |
9618 | associated with each history entry is written to the history file, | |
9619 | marked with the history comment character. | |
9620 | When the history file is read, lines beginning with the history | |
9621 | comment character followed immediately by a digit are interpreted | |
9622 | as timestamps for the previous history line. | |
9623 | The return value is 0 unless an invalid option is encountered, an | |
9624 | error occurs while reading or writing the history file, an invalid | |
9625 | <I>offset</I> is supplied as an argument to <B>-d</B>, or the | |
9626 | history expansion supplied as an argument to <B>-p</B> fails. | |
9627 | </DL> | |
9628 | ||
9629 | <DT><B>jobs</B> [<B>-lnprs</B>] [ <I>jobspec</I> ... ]<DD> | |
9630 | ||
9631 | <DT><B>jobs</B> <B>-x</B> <I>command</I> [ <I>args</I> ... ]<DD> | |
9632 | ||
9633 | The first form lists the active jobs. The options have the following | |
9634 | meanings: | |
9635 | <DL COMPACT><DT><DD> | |
9636 | ||
9637 | <DL COMPACT> | |
9638 | <DT><B>-l</B> | |
9639 | ||
9640 | <DD> | |
9641 | List process IDs | |
9642 | in addition to the normal information. | |
9643 | <DT><B>-p</B> | |
9644 | ||
9645 | <DD> | |
9646 | List only the process ID of the job's process group | |
9647 | leader. | |
9648 | <DT><B>-n</B> | |
9649 | ||
9650 | <DD> | |
9651 | Display information only about jobs that have changed status since | |
9652 | the user was last notified of their status. | |
9653 | <DT><B>-r</B> | |
9654 | ||
9655 | <DD> | |
9656 | Restrict output to running jobs. | |
9657 | <DT><B>-s</B> | |
9658 | ||
9659 | <DD> | |
9660 | Restrict output to stopped jobs. | |
9661 | ||
9662 | </DL> | |
9663 | <P> | |
9664 | ||
9665 | If | |
9666 | <I>jobspec</I> | |
9667 | ||
9668 | is given, output is restricted to information about that job. | |
9669 | The return status is 0 unless an invalid option is encountered | |
9670 | or an invalid | |
9671 | <I>jobspec</I> | |
9672 | ||
9673 | is supplied. | |
9674 | <P> | |
9675 | ||
9676 | If the | |
9677 | <B>-x</B> | |
9678 | ||
9679 | option is supplied, | |
9680 | <B>jobs</B> | |
9681 | ||
9682 | replaces any | |
9683 | <I>jobspec</I> | |
9684 | ||
9685 | found in | |
9686 | <I>command</I> | |
9687 | ||
9688 | or | |
9689 | <I>args</I> | |
9690 | ||
9691 | with the corresponding process group ID, and executes | |
9692 | <I>command</I> | |
9693 | ||
9694 | passing it | |
9695 | <I>args</I>, | |
9696 | ||
9697 | returning its exit status. | |
9698 | </DL> | |
9699 | ||
9700 | <DT><B>kill</B> [<B>-s</B> <I>sigspec</I> | <B>-n</B> <I>signum</I> | <B>-</B><I>sigspec</I>] [<I>pid</I> | <I>jobspec</I>] ...<DD> | |
9701 | ||
9702 | <DT><B>kill</B> <B>-l</B> [<I>sigspec</I> | <I>exit_status</I>]<DD> | |
9703 | ||
9704 | Send the signal named by | |
9705 | <I>sigspec</I> | |
9706 | ||
9707 | or | |
9708 | <I>signum</I> | |
9709 | ||
9710 | to the processes named by | |
9711 | <I>pid</I> | |
9712 | ||
9713 | or | |
9714 | <I>jobspec</I>. | |
9715 | ||
9716 | <I>sigspec</I> | |
9717 | ||
9718 | is either a case-insensitive signal name such as | |
9719 | <FONT SIZE=-1><B>SIGKILL</B> | |
9720 | ||
9721 | </FONT> | |
9722 | (with or without the | |
9723 | <FONT SIZE=-1><B>SIG</B> | |
9724 | ||
9725 | </FONT> | |
9726 | prefix) or a signal number; | |
9727 | <I>signum</I> | |
9728 | ||
9729 | is a signal number. | |
9730 | If | |
9731 | <I>sigspec</I> | |
9732 | ||
9733 | is not present, then | |
9734 | <FONT SIZE=-1><B>SIGTERM</B> | |
9735 | ||
9736 | </FONT> | |
9737 | is assumed. | |
9738 | An argument of | |
9739 | <B>-l</B> | |
9740 | ||
9741 | lists the signal names. | |
9742 | If any arguments are supplied when | |
9743 | <B>-l</B> | |
9744 | ||
9745 | is given, the names of the signals corresponding to the arguments are | |
9746 | listed, and the return status is 0. | |
9747 | The <I>exit_status</I> argument to | |
9748 | <B>-l</B> | |
9749 | ||
9750 | is a number specifying either a signal number or the exit status of | |
9751 | a process terminated by a signal. | |
9752 | <B>kill</B> | |
9753 | ||
9754 | returns true if at least one signal was successfully sent, or false | |
9755 | if an error occurs or an invalid option is encountered. | |
9756 | <DT><B>let</B> <I>arg</I> [<I>arg</I> ...]<DD> | |
9757 | Each | |
9758 | <I>arg</I> | |
9759 | ||
9760 | is an arithmetic expression to be evaluated (see | |
9761 | <FONT SIZE=-1><B>ARITHMETIC EVALUATION</B>). | |
9762 | ||
9763 | </FONT> | |
9764 | If the last | |
9765 | <I>arg</I> | |
9766 | ||
9767 | evaluates to 0, | |
9768 | <B>let</B> | |
9769 | ||
9770 | returns 1; 0 is returned otherwise. | |
9771 | <DT><B>local</B> [<I>option</I>] [<I>name</I>[=<I>value</I>] ...]<DD> | |
9772 | For each argument, a local variable named | |
9773 | <I>name </I> | |
9774 | ||
9775 | is created, and assigned | |
9776 | <I>value</I>. | |
9777 | ||
9778 | The <I>option</I> can be any of the options accepted by <B>declare</B>. | |
9779 | When | |
9780 | <B>local</B> | |
9781 | ||
9782 | is used within a function, it causes the variable | |
9783 | <I>name</I> | |
9784 | ||
9785 | to have a visible scope restricted to that function and its children. | |
9786 | With no operands, | |
9787 | <B>local</B> | |
9788 | ||
9789 | writes a list of local variables to the standard output. It is | |
9790 | an error to use | |
9791 | <B>local</B> | |
9792 | ||
9793 | when not within a function. The return status is 0 unless | |
9794 | <B>local</B> | |
9795 | ||
9796 | is used outside a function, an invalid | |
9797 | <I>name</I> | |
9798 | ||
9799 | is supplied, or | |
9800 | <I>name</I> is a readonly variable. | |
9801 | <DT><B>logout</B> | |
9802 | ||
9803 | <DD> | |
9804 | Exit a login shell. | |
9805 | <DT><B>mapfile</B> [<B>-n</B> <I>count</I>] [<B>-O</B> <I>origin</I>] [<B>-s</B> <I>count</I>] [<B>-t</B>] [<B>-u</B> <I>fd</I>] [<B>-C</B> <I>callback</I>] [<B>-c</B> <I>quantum</I>] [<I>array</I>]<DD> | |
9806 | ||
9807 | <DT><B>readarray</B> [<B>-n</B> <I>count</I>] [<B>-O</B> <I>origin</I>] [<B>-s</B> <I>count</I>] [<B>-t</B>] [<B>-u</B> <I>fd</I>] [<B>-C</B> <I>callback</I>] [<B>-c</B> <I>quantum</I>] [<I>array</I>]<DD> | |
9808 | ||
9809 | Read lines from the standard input into array variable | |
9810 | <I>array</I>, | |
9811 | ||
9812 | or from file descriptor | |
9813 | <I>fd</I> | |
9814 | ||
9815 | if the | |
9816 | <B>-u</B> | |
9817 | ||
9818 | option is supplied. | |
9819 | The variable <B>MAPFILE</B> is the default <I>array</I>. | |
9820 | Options, if supplied, have the following meanings: | |
9821 | <DL COMPACT><DT><DD> | |
9822 | ||
9823 | <DL COMPACT> | |
9824 | <DT><B>-n</B> | |
9825 | ||
9826 | <DD> | |
9827 | Copy at most | |
9828 | <I>count</I> | |
9829 | ||
9830 | lines. If <I>count</I> is 0, all lines are copied. | |
9831 | <DT><B>-O</B> | |
9832 | ||
9833 | <DD> | |
9834 | Begin assigning to | |
9835 | <I>array</I> | |
9836 | ||
9837 | at index | |
9838 | <I>origin</I>. | |
9839 | ||
9840 | The default index is 0. | |
9841 | <DT><B>-s</B> | |
9842 | ||
9843 | <DD> | |
9844 | Discard the first <I>count</I> lines read. | |
9845 | <DT><B>-t</B> | |
9846 | ||
9847 | <DD> | |
9848 | Remove a trailing line from each line read. | |
9849 | <DT><B>-u</B> | |
9850 | ||
9851 | <DD> | |
9852 | Read lines from file descriptor <I>fd</I> instead of the standard input. | |
9853 | <DT><B>-C</B> | |
9854 | ||
9855 | <DD> | |
9856 | Evaluate | |
9857 | <I>callback</I> | |
9858 | ||
9859 | each time <I>quantum</I> lines are read. The <B>-c</B> option specifies | |
9860 | <I>quantum</I>. | |
9861 | ||
9862 | <DT><B>-c</B> | |
9863 | ||
9864 | <DD> | |
9865 | Specify the number of lines read between each call to | |
9866 | <I>callback</I>. | |
9867 | ||
9868 | ||
9869 | </DL> | |
9870 | <P> | |
9871 | ||
9872 | If | |
9873 | <B>-C</B> | |
9874 | ||
9875 | is specified without | |
9876 | <B>-c</B>, | |
9877 | ||
9878 | the default quantum is 5000. | |
9879 | When <I>callback</I> is evaluated, it is supplied the index of the next | |
9880 | array element to be assigned as an additional argument. | |
9881 | <I>callback</I> is evaluated after the line is read but before the | |
9882 | array element is assigned. | |
9883 | <P> | |
9884 | ||
9885 | If not supplied with an explicit origin, <B>mapfile</B> will clear <I>array</I> | |
9886 | before assigning to it. | |
9887 | <P> | |
9888 | ||
9889 | <B>mapfile</B> returns successfully unless an invalid option or option | |
9890 | argument is supplied, or <I>array</I> is invalid or unassignable. | |
9891 | </DL> | |
9892 | ||
9893 | <DT><B>popd</B> [-<B>n</B>] [+<I>n</I>] [-<I>n</I>]<DD> | |
9894 | Removes entries from the directory stack. With no arguments, | |
9895 | removes the top directory from the stack, and performs a | |
9896 | <B>cd</B> | |
9897 | ||
9898 | to the new top directory. | |
9899 | Arguments, if supplied, have the following meanings: | |
9900 | <DL COMPACT><DT><DD> | |
9901 | ||
9902 | <DL COMPACT> | |
9903 | <DT><B>-n</B> | |
9904 | ||
9905 | <DD> | |
9906 | Suppresses the normal change of directory when removing directories | |
9907 | from the stack, so that only the stack is manipulated. | |
9908 | <DT><B>+</B><I>n</I><DD> | |
9909 | Removes the <I>n</I>th entry counting from the left of the list | |
9910 | shown by | |
9911 | <B>dirs</B>, | |
9912 | ||
9913 | starting with zero. For example: | |
9914 | ||
9915 | <TT>popd +0</TT> | |
9916 | removes the first directory, | |
9917 | ||
9918 | <TT>popd +1</TT> | |
9919 | the second. | |
9920 | <DT><B>-</B><I>n</I><DD> | |
9921 | Removes the <I>n</I>th entry counting from the right of the list | |
9922 | shown by | |
9923 | <B>dirs</B>, | |
9924 | ||
9925 | starting with zero. For example: | |
9926 | ||
9927 | <TT>popd -0</TT> | |
9928 | removes the last directory, | |
9929 | ||
9930 | <TT>popd -1</TT> | |
9931 | the next to last. | |
9932 | ||
9933 | </DL> | |
9934 | <P> | |
9935 | ||
9936 | If the | |
9937 | <B>popd</B> | |
9938 | ||
9939 | command is successful, a | |
9940 | <B>dirs</B> | |
9941 | ||
9942 | is performed as well, and the return status is 0. | |
9943 | <B>popd</B> | |
9944 | ||
9945 | returns false if an invalid option is encountered, the directory stack | |
9946 | is empty, a non-existent directory stack entry is specified, or the | |
9947 | directory change fails. | |
9948 | </DL> | |
9949 | ||
9950 | <DT><B>printf</B> [<B>-v</B> <I>var</I>] <I>format</I> [<I>arguments</I>]<DD> | |
9951 | Write the formatted <I>arguments</I> to the standard output under the | |
9952 | control of the <I>format</I>. | |
9953 | The <I>format</I> is a character string which contains three types of objects: | |
9954 | plain characters, which are simply copied to standard output, character | |
9955 | escape sequences, which are converted and copied to the standard output, and | |
9956 | format specifications, each of which causes printing of the next successive | |
9957 | <I>argument</I>. | |
9958 | In addition to the standard <I>printf</I>(1) formats, <B>%b</B> causes | |
9959 | <B>printf</B> to expand backslash escape sequences in the corresponding | |
9960 | <I>argument</I> (except that <B>\c</B> terminates output, backslashes in | |
9961 | <B>\aq</B>, <B>\"</B>, and <B>\?</B> are not removed, and octal escapes | |
9962 | beginning with <B>\0</B> may contain up to four digits), | |
9963 | and <B>%q</B> causes <B>printf</B> to output the corresponding | |
9964 | <I>argument</I> in a format that can be reused as shell input. | |
9965 | <P> | |
9966 | The <B>-v</B> option causes the output to be assigned to the variable | |
9967 | <I>var</I> rather than being printed to the standard output. | |
9968 | <P> | |
9969 | The <I>format</I> is reused as necessary to consume all of the <I>arguments</I>. | |
9970 | If the <I>format</I> requires more <I>arguments</I> than are supplied, the | |
9971 | extra format specifications behave as if a zero value or null string, as | |
9972 | appropriate, had been supplied. The return value is zero on success, | |
9973 | non-zero on failure. | |
9974 | <DT><B>pushd</B> [<B>-n</B>] [+<I>n</I>] [-<I>n</I>]<DD> | |
9975 | ||
9976 | <DT><B>pushd</B> [<B>-n</B>] [<I>dir</I>]<DD> | |
9977 | ||
9978 | Adds a directory to the top of the directory stack, or rotates | |
9979 | the stack, making the new top of the stack the current working | |
9980 | directory. With no arguments, exchanges the top two directories | |
9981 | and returns 0, unless the directory stack is empty. | |
9982 | Arguments, if supplied, have the following meanings: | |
9983 | <DL COMPACT><DT><DD> | |
9984 | ||
9985 | <DL COMPACT> | |
9986 | <DT><B>-n</B> | |
9987 | ||
9988 | <DD> | |
9989 | Suppresses the normal change of directory when adding directories | |
9990 | to the stack, so that only the stack is manipulated. | |
9991 | <DT><B>+</B><I>n</I><DD> | |
9992 | Rotates the stack so that the <I>n</I>th directory | |
9993 | (counting from the left of the list shown by | |
9994 | <B>dirs</B>, | |
9995 | ||
9996 | starting with zero) | |
9997 | is at the top. | |
9998 | <DT><B>-</B><I>n</I><DD> | |
9999 | Rotates the stack so that the <I>n</I>th directory | |
10000 | (counting from the right of the list shown by | |
10001 | <B>dirs</B>, | |
10002 | ||
10003 | starting with zero) is at the top. | |
10004 | <DT><I>dir</I> | |
10005 | ||
10006 | <DD> | |
10007 | Adds | |
10008 | <I>dir</I> | |
10009 | ||
10010 | to the directory stack at the top, making it the | |
10011 | new current working directory. | |
10012 | ||
10013 | </DL> | |
10014 | <P> | |
10015 | ||
10016 | If the | |
10017 | <B>pushd</B> | |
10018 | ||
10019 | command is successful, a | |
10020 | <B>dirs</B> | |
10021 | ||
10022 | is performed as well. | |
10023 | If the first form is used, | |
10024 | <B>pushd</B> | |
10025 | ||
10026 | returns 0 unless the cd to | |
10027 | <I>dir</I> | |
10028 | ||
10029 | fails. With the second form, | |
10030 | <B>pushd</B> | |
10031 | ||
10032 | returns 0 unless the directory stack is empty, | |
10033 | a non-existent directory stack element is specified, | |
10034 | or the directory change to the specified new current directory | |
10035 | fails. | |
10036 | </DL> | |
10037 | ||
10038 | <DT><B>pwd</B> [<B>-LP</B>]<DD> | |
10039 | Print the absolute pathname of the current working directory. | |
10040 | The pathname printed contains no symbolic links if the | |
10041 | <B>-P</B> | |
10042 | ||
10043 | option is supplied or the | |
10044 | <B>-o physical</B> | |
10045 | ||
10046 | option to the | |
10047 | <B>set</B> | |
10048 | ||
10049 | builtin command is enabled. | |
10050 | If the | |
10051 | <B>-L</B> | |
10052 | ||
10053 | option is used, the pathname printed may contain symbolic links. | |
10054 | The return status is 0 unless an error occurs while | |
10055 | reading the name of the current directory or an | |
10056 | invalid option is supplied. | |
10057 | <DT><B>read</B> [<B>-ers</B>] [<B>-a</B> <I>aname</I>] [<B>-d</B> <I>delim</I>] [<B>-</B> <I>text</I>] [<B>-n</B> <I>nchars</I>] [<B>-p</B> <I>prompt</I>] [<B>-t</B> <I>timeout</I>] [<B>-u</B> <I>fd</I>] [<I>name</I> ...]<DD> | |
10058 | One line is read from the standard input, or from the file descriptor | |
10059 | <I>fd</I> supplied as an argument to the <B>-u</B> option, and the first word | |
10060 | is assigned to the first | |
10061 | <I>name</I>, | |
10062 | ||
10063 | the second word to the second | |
10064 | <I>name</I>, | |
10065 | ||
10066 | and so on, with leftover words and their intervening separators assigned | |
10067 | to the last | |
10068 | <I>name</I>. | |
10069 | ||
10070 | If there are fewer words read from the input stream than names, | |
10071 | the remaining names are assigned empty values. | |
10072 | The characters in | |
10073 | <FONT SIZE=-1><B>IFS</B> | |
10074 | ||
10075 | </FONT> | |
10076 | are used to split the line into words. | |
10077 | The backslash character (<B>\</B>) may be used to remove any special | |
10078 | meaning for the next character read and for line continuation. | |
10079 | Options, if supplied, have the following meanings: | |
10080 | <DL COMPACT><DT><DD> | |
10081 | ||
10082 | <DL COMPACT> | |
10083 | <DT><B>-a </B><I>aname</I> | |
10084 | ||
10085 | <DD> | |
10086 | The words are assigned to sequential indices | |
10087 | of the array variable | |
10088 | <I>aname</I>, | |
10089 | ||
10090 | starting at 0. | |
10091 | <I>aname</I> | |
10092 | ||
10093 | is unset before any new values are assigned. | |
10094 | Other <I>name</I> arguments are ignored. | |
10095 | <DT><B>-d </B><I>delim</I> | |
10096 | ||
10097 | <DD> | |
10098 | The first character of <I>delim</I> is used to terminate the input line, | |
10099 | rather than newline. | |
10100 | <DT><B>-e</B> | |
10101 | ||
10102 | <DD> | |
10103 | If the standard input | |
10104 | is coming from a terminal, | |
10105 | <B>readline</B> | |
10106 | ||
10107 | (see | |
10108 | <FONT SIZE=-1><B>READLINE</B> | |
10109 | ||
10110 | </FONT> | |
10111 | above) is used to obtain the line. | |
10112 | Readline uses the current (or default, if line editing was not previously | |
10113 | active) editing settings. | |
10114 | <DT><B>-i </B><I>text</I> | |
10115 | ||
10116 | <DD> | |
10117 | If | |
10118 | <B>readline</B> | |
10119 | ||
10120 | is being used to read the line, <I>text</I> is placed into the editing | |
10121 | buffer before editing begins. | |
10122 | <DT><B>-n </B><I>nchars</I> | |
10123 | ||
10124 | <DD> | |
10125 | <B>read</B> returns after reading <I>nchars</I> characters rather than | |
10126 | waiting for a complete line of input. | |
10127 | <DT><B>-p </B><I>prompt</I> | |
10128 | ||
10129 | <DD> | |
10130 | Display <I>prompt</I> on standard error, without a | |
10131 | trailing newline, before attempting to read any input. The prompt | |
10132 | is displayed only if input is coming from a terminal. | |
10133 | <DT><B>-r</B> | |
10134 | ||
10135 | <DD> | |
10136 | Backslash does not act as an escape character. | |
10137 | The backslash is considered to be part of the line. | |
10138 | In particular, a backslash-newline pair may not be used as a line | |
10139 | continuation. | |
10140 | <DT><B>-s</B> | |
10141 | ||
10142 | <DD> | |
10143 | Silent mode. If input is coming from a terminal, characters are | |
10144 | not echoed. | |
10145 | <DT><B>-t </B><I>timeout</I> | |
10146 | ||
10147 | <DD> | |
10148 | Cause <B>read</B> to time out and return failure if a complete line of | |
10149 | input is not read within <I>timeout</I> seconds. | |
10150 | <I>timeout</I> may be a decimal number with a fractional portion following | |
10151 | the decimal point. | |
10152 | This option is only effective if <B>read</B> is reading input from a | |
10153 | terminal, pipe, or other special file; it has no effect when reading | |
10154 | from regular files. | |
10155 | If <I>timeout</I> is 0, <B>read</B> returns success if input is available on | |
10156 | the specified file descriptor, failure otherwise. | |
10157 | The exit status is greater than 128 if the timeout is exceeded. | |
10158 | <DT><B>-u </B><I>fd</I> | |
10159 | ||
10160 | <DD> | |
10161 | Read input from file descriptor <I>fd</I>. | |
10162 | ||
10163 | </DL> | |
10164 | <P> | |
10165 | ||
10166 | If no | |
10167 | <I>names</I> | |
10168 | ||
10169 | are supplied, the line read is assigned to the variable | |
10170 | <FONT SIZE=-1><B>REPLY</B>. | |
10171 | ||
10172 | </FONT> | |
10173 | The return code is zero, unless end-of-file is encountered, <B>read</B> | |
10174 | times out (in which case the return code is greater than 128), or an | |
10175 | invalid file descriptor is supplied as the argument to <B>-u</B>. | |
10176 | </DL> | |
10177 | ||
10178 | <DT><B>readonly</B> [<B>-aApf</B>] [<I>name</I>[=<I>word</I>] ...]<DD> | |
10179 | ||
10180 | The given | |
10181 | <I>names</I> are marked readonly; the values of these | |
10182 | <I>names</I> | |
10183 | ||
10184 | may not be changed by subsequent assignment. | |
10185 | If the | |
10186 | <B>-f</B> | |
10187 | ||
10188 | option is supplied, the functions corresponding to the | |
10189 | <I>names</I> are so | |
10190 | marked. | |
10191 | The | |
10192 | <B>-a</B> | |
10193 | ||
10194 | option restricts the variables to indexed arrays; the | |
10195 | <B>-A</B> | |
10196 | ||
10197 | option restricts the variables to associative arrays. | |
10198 | If no | |
10199 | <I>name</I> | |
10200 | ||
10201 | arguments are given, or if the | |
10202 | <B>-p</B> | |
10203 | ||
10204 | option is supplied, a list of all readonly names is printed. | |
10205 | The | |
10206 | <B>-p</B> | |
10207 | ||
10208 | option causes output to be displayed in a format that | |
10209 | may be reused as input. | |
10210 | If a variable name is followed by =<I>word</I>, the value of | |
10211 | the variable is set to <I>word</I>. | |
10212 | The return status is 0 unless an invalid option is encountered, | |
10213 | one of the | |
10214 | <I>names</I> | |
10215 | ||
10216 | is not a valid shell variable name, or | |
10217 | <B>-f</B> | |
10218 | ||
10219 | is supplied with a | |
10220 | <I>name</I> | |
10221 | ||
10222 | that is not a function. | |
10223 | <DT><B>return</B> [<I>n</I>]<DD> | |
10224 | Causes a function to exit with the return value specified by | |
10225 | <I>n</I>. | |
10226 | ||
10227 | If | |
10228 | <I>n</I> | |
10229 | ||
10230 | is omitted, the return status is that of the last command | |
10231 | executed in the function body. If used outside a function, | |
10232 | but during execution of a script by the | |
10233 | <B>.</B> | |
10234 | ||
10235 | (<B>source</B>) command, it causes the shell to stop executing | |
10236 | that script and return either | |
10237 | <I>n</I> | |
10238 | ||
10239 | or the exit status of the last command executed within the | |
10240 | script as the exit status of the script. If used outside a | |
10241 | function and not during execution of a script by <B>.</B>, | |
10242 | the return status is false. | |
10243 | Any command associated with the <B>RETURN</B> trap is executed | |
10244 | before execution resumes after the function or script. | |
10245 | <DT><B>set</B> [<B>--abefhkmnptuvxBCEHPT</B>] [<B>-o</B> <I>option</I>] [<I>arg</I> ...]<DD> | |
10246 | ||
10247 | <DT><B>set</B> [<B>+abefhkmnptuvxBCEHPT</B>] [<B>+o</B> <I>option</I>] [<I>arg</I> ...]<DD> | |
10248 | ||
10249 | Without options, the name and value of each shell variable are displayed | |
10250 | in a format that can be reused as input | |
10251 | for setting or resetting the currently-set variables. | |
10252 | Read-only variables cannot be reset. | |
10253 | In <I>posix mode</I>, only shell variables are listed. | |
10254 | The output is sorted according to the current locale. | |
10255 | When options are specified, they set or unset shell attributes. | |
10256 | Any arguments remaining after option processing are treated | |
10257 | as values for the positional parameters and are assigned, in order, to | |
10258 | <B>$1</B>, | |
10259 | ||
10260 | <B>$2</B>, | |
10261 | ||
10262 | <B>...</B> | |
10263 | ||
10264 | <B>$</B><I>n</I>. | |
10265 | ||
10266 | Options, if specified, have the following meanings: | |
10267 | <DL COMPACT><DT><DD> | |
10268 | ||
10269 | <DL COMPACT> | |
10270 | <DT><B>-a</B> | |
10271 | ||
10272 | <DD> | |
10273 | Automatically mark variables and functions which are modified or | |
10274 | created for export to the environment of subsequent commands. | |
10275 | <DT><B>-b</B> | |
10276 | ||
10277 | <DD> | |
10278 | Report the status of terminated background jobs | |
10279 | immediately, rather than before the next primary prompt. This is | |
10280 | effective only when job control is enabled. | |
10281 | <DT><B>-e</B> | |
10282 | ||
10283 | <DD> | |
10284 | Exit immediately if a <I>simple command</I> (see | |
10285 | <FONT SIZE=-1><B>SHELL GRAMMAR</B> | |
10286 | ||
10287 | </FONT> | |
10288 | above) exits with a non-zero status. | |
10289 | The shell does not exit if the | |
10290 | command that fails is part of the command list immediately following a | |
10291 | <B>while</B> | |
10292 | ||
10293 | or | |
10294 | <B>until</B> | |
10295 | ||
10296 | keyword, | |
10297 | part of the test in an | |
10298 | <B>if</B> | |
10299 | ||
10300 | statement, part of a command executed in a | |
10301 | <B>&&</B> | |
10302 | ||
10303 | or | |
10304 | <B>||</B> | |
10305 | ||
10306 | list, | |
10307 | any command in a pipeline but the last, | |
10308 | or if the command's return value is | |
10309 | being inverted via | |
10310 | <B>!</B>. | |
10311 | ||
10312 | Failing simple commands that are part of shell functions or command lists | |
10313 | enclosed in braces or parentheses satisfying the above conditions do not | |
10314 | cause the shell to exit. | |
10315 | A trap on <B>ERR</B>, if set, is executed before the shell exits. | |
10316 | <DT><B>-f</B> | |
10317 | ||
10318 | <DD> | |
10319 | Disable pathname expansion. | |
10320 | <DT><B>-h</B> | |
10321 | ||
10322 | <DD> | |
10323 | Remember the location of commands as they are looked up for execution. | |
10324 | This is enabled by default. | |
10325 | <DT><B>-k</B> | |
10326 | ||
10327 | <DD> | |
10328 | All arguments in the form of assignment statements | |
10329 | are placed in the environment for a command, not just | |
10330 | those that precede the command name. | |
10331 | <DT><B>-m</B> | |
10332 | ||
10333 | <DD> | |
10334 | Monitor mode. Job control is enabled. This option is on | |
10335 | by default for interactive shells on systems that support | |
10336 | it (see | |
10337 | <FONT SIZE=-1><B>JOB CONTROL</B> | |
10338 | ||
10339 | </FONT> | |
10340 | above). Background processes run in a separate process | |
10341 | group and a line containing their exit status is printed | |
10342 | upon their completion. | |
10343 | <DT><B>-n</B> | |
10344 | ||
10345 | <DD> | |
10346 | Read commands but do not execute them. This may be used to | |
10347 | check a shell script for syntax errors. This is ignored by | |
10348 | interactive shells. | |
10349 | <DT><B>-o </B><I>option-name</I> | |
10350 | ||
10351 | <DD> | |
10352 | The <I>option-name</I> can be one of the following: | |
10353 | <DL COMPACT><DT><DD> | |
10354 | <DL COMPACT> | |
10355 | <DT><B>allexport</B> | |
10356 | ||
10357 | <DD> | |
10358 | Same as | |
10359 | <B>-a</B>. | |
10360 | ||
10361 | <DT><B>braceexpand</B> | |
10362 | ||
10363 | <DD> | |
10364 | Same as | |
10365 | <B>-B</B>. | |
10366 | ||
10367 | <DT><B>emacs</B> | |
10368 | ||
10369 | <DD> | |
10370 | Use an emacs-style command line editing interface. This is enabled | |
10371 | by default when the shell is interactive, unless the shell is started | |
10372 | with the | |
10373 | <B>--noediting</B> | |
10374 | ||
10375 | option. | |
10376 | This also affects the editing interface used for <B>read -e</B>. | |
10377 | <DT><B>errtrace</B> | |
10378 | ||
10379 | <DD> | |
10380 | Same as | |
10381 | <B>-E</B>. | |
10382 | ||
10383 | <DT><B>functrace</B> | |
10384 | ||
10385 | <DD> | |
10386 | Same as | |
10387 | <B>-T</B>. | |
10388 | ||
10389 | <DT><B>errexit</B> | |
10390 | ||
10391 | <DD> | |
10392 | Same as | |
10393 | <B>-e</B>. | |
10394 | ||
10395 | <DT><B>hashall</B> | |
10396 | ||
10397 | <DD> | |
10398 | Same as | |
10399 | <B>-h</B>. | |
10400 | ||
10401 | <DT><B>histexpand</B> | |
10402 | ||
10403 | <DD> | |
10404 | Same as | |
10405 | <B>-H</B>. | |
10406 | ||
10407 | <DT><B>history</B> | |
10408 | ||
10409 | <DD> | |
10410 | Enable command history, as described above under | |
10411 | <FONT SIZE=-1><B>HISTORY</B>. | |
10412 | ||
10413 | </FONT> | |
10414 | This option is on by default in interactive shells. | |
10415 | <DT><B>ignoreeof</B> | |
10416 | ||
10417 | <DD> | |
10418 | The effect is as if the shell command | |
10419 | <TT>IGNOREEOF=10</TT> | |
10420 | ||
10421 | had been executed | |
10422 | (see | |
10423 | <B>Shell Variables</B> | |
10424 | ||
10425 | above). | |
10426 | <DT><B>keyword</B> | |
10427 | ||
10428 | <DD> | |
10429 | Same as | |
10430 | <B>-k</B>. | |
10431 | ||
10432 | <DT><B>monitor</B> | |
10433 | ||
10434 | <DD> | |
10435 | Same as | |
10436 | <B>-m</B>. | |
10437 | ||
10438 | <DT><B>noclobber</B> | |
10439 | ||
10440 | <DD> | |
10441 | Same as | |
10442 | <B>-C</B>. | |
10443 | ||
10444 | <DT><B>noexec</B> | |
10445 | ||
10446 | <DD> | |
10447 | Same as | |
10448 | <B>-n</B>. | |
10449 | ||
10450 | <DT><B>noglob</B> | |
10451 | ||
10452 | <DD> | |
10453 | Same as | |
10454 | <B>-f</B>. | |
10455 | ||
10456 | <DT><B>nolog</B> | |
10457 | ||
10458 | <DD> | |
10459 | Currently ignored. | |
10460 | <DT><B>notify</B> | |
10461 | ||
10462 | <DD> | |
10463 | Same as | |
10464 | <B>-b</B>. | |
10465 | ||
10466 | <DT><B>nounset</B> | |
10467 | ||
10468 | <DD> | |
10469 | Same as | |
10470 | <B>-u</B>. | |
10471 | ||
10472 | <DT><B>onecmd</B> | |
10473 | ||
10474 | <DD> | |
10475 | Same as | |
10476 | <B>-t</B>. | |
10477 | ||
10478 | <DT><B>physical</B> | |
10479 | ||
10480 | <DD> | |
10481 | Same as | |
10482 | <B>-P</B>. | |
10483 | ||
10484 | <DT><B>pipefail</B> | |
10485 | ||
10486 | <DD> | |
10487 | If set, the return value of a pipeline is the value of the last | |
10488 | (rightmost) command to exit with a non-zero status, or zero if all | |
10489 | commands in the pipeline exit successfully. | |
10490 | This option is disabled by default. | |
10491 | <DT><B>posix</B> | |
10492 | ||
10493 | <DD> | |
10494 | Change the behavior of | |
10495 | <B>bash</B> | |
10496 | ||
10497 | where the default operation differs | |
10498 | from the POSIX standard to match the standard (<I>posix mode</I>). | |
10499 | <DT><B>privileged</B> | |
10500 | ||
10501 | <DD> | |
10502 | Same as | |
10503 | <B>-p</B>. | |
10504 | ||
10505 | <DT><B>verbose</B> | |
10506 | ||
10507 | <DD> | |
10508 | Same as | |
10509 | <B>-v</B>. | |
10510 | ||
10511 | <DT><B>vi</B> | |
10512 | ||
10513 | <DD> | |
10514 | Use a vi-style command line editing interface. | |
10515 | This also affects the editing interface used for <B>read -e</B>. | |
10516 | <DT><B>xtrace</B> | |
10517 | ||
10518 | <DD> | |
10519 | Same as | |
10520 | <B>-x</B>. | |
10521 | ||
10522 | <P> | |
10523 | </DL> | |
10524 | <P> | |
10525 | ||
10526 | If | |
10527 | <B>-o</B> | |
10528 | ||
10529 | is supplied with no <I>option-name</I>, the values of the current options are | |
10530 | printed. | |
10531 | If | |
10532 | <B>+o</B> | |
10533 | ||
10534 | is supplied with no <I>option-name</I>, a series of | |
10535 | <B>set</B> | |
10536 | ||
10537 | commands to recreate the current option settings is displayed on | |
10538 | the standard output. | |
10539 | </DL> | |
10540 | ||
10541 | <DT><B>-p</B> | |
10542 | ||
10543 | <DD> | |
10544 | Turn on | |
10545 | <I>privileged</I> | |
10546 | ||
10547 | mode. In this mode, the | |
10548 | <FONT SIZE=-1><B>$ENV</B> | |
10549 | ||
10550 | </FONT> | |
10551 | and | |
10552 | <FONT SIZE=-1><B>$BASH_ENV</B> | |
10553 | ||
10554 | </FONT> | |
10555 | files are not processed, shell functions are not inherited from the | |
10556 | environment, and the | |
10557 | <FONT SIZE=-1><B>SHELLOPTS</B>, | |
10558 | ||
10559 | </FONT> | |
10560 | <B>CDPATH</B>, | |
10561 | ||
10562 | and | |
10563 | <B>GLOBIGNORE</B> | |
10564 | ||
10565 | variables, if they appear in the environment, are ignored. | |
10566 | If the shell is started with the effective user (group) id not equal to the | |
10567 | real user (group) id, and the <B>-p</B> option is not supplied, these actions | |
10568 | are taken and the effective user id is set to the real user id. | |
10569 | If the <B>-p</B> option is supplied at startup, the effective user id is | |
10570 | not reset. | |
10571 | Turning this option off causes the effective user | |
10572 | and group ids to be set to the real user and group ids. | |
10573 | <DT><B>-t</B> | |
10574 | ||
10575 | <DD> | |
10576 | Exit after reading and executing one command. | |
10577 | <DT><B>-u</B> | |
10578 | ||
10579 | <DD> | |
10580 | Treat unset variables as an error when performing | |
10581 | parameter expansion. If expansion is attempted on an | |
10582 | unset variable, the shell prints an error message, and, | |
10583 | if not interactive, exits with a non-zero status. | |
10584 | <DT><B>-v</B> | |
10585 | ||
10586 | <DD> | |
10587 | Print shell input lines as they are read. | |
10588 | <DT><B>-x</B> | |
10589 | ||
10590 | <DD> | |
10591 | After expanding each <I>simple command</I>, | |
10592 | <B>for</B> command, <B>case</B> command, <B>select</B> command, or | |
10593 | arithmetic <B>for</B> command, display the expanded value of | |
10594 | <FONT SIZE=-1><B>PS4</B>, | |
10595 | ||
10596 | </FONT> | |
10597 | followed by the command and its expanded arguments | |
10598 | or associated word list. | |
10599 | <DT><B>-B</B> | |
10600 | ||
10601 | <DD> | |
10602 | The shell performs brace expansion (see | |
10603 | <B>Brace Expansion</B> | |
10604 | ||
10605 | above). This is on by default. | |
10606 | <DT><B>-C</B> | |
10607 | ||
10608 | <DD> | |
10609 | If set, | |
10610 | <B>bash</B> | |
10611 | ||
10612 | does not overwrite an existing file with the | |
10613 | <B>></B>, | |
10614 | ||
10615 | <B>>&</B>, | |
10616 | ||
10617 | and | |
10618 | <B><></B> | |
10619 | ||
10620 | redirection operators. This may be overridden when | |
10621 | creating output files by using the redirection operator | |
10622 | <B>>|</B> | |
10623 | ||
10624 | instead of | |
10625 | <B>></B>. | |
10626 | ||
10627 | <DT><B>-E</B> | |
10628 | ||
10629 | <DD> | |
10630 | If set, any trap on <B>ERR</B> is inherited by shell functions, command | |
10631 | substitutions, and commands executed in a subshell environment. | |
10632 | The <B>ERR</B> trap is normally not inherited in such cases. | |
10633 | <DT><B>-H</B> | |
10634 | ||
10635 | <DD> | |
10636 | Enable | |
10637 | <B>!</B> | |
10638 | ||
10639 | style history substitution. This option is on by | |
10640 | default when the shell is interactive. | |
10641 | <DT><B>-P</B> | |
10642 | ||
10643 | <DD> | |
10644 | If set, the shell does not follow symbolic links when executing | |
10645 | commands such as | |
10646 | <B>cd</B> | |
10647 | ||
10648 | that change the current working directory. It uses the | |
10649 | physical directory structure instead. By default, | |
10650 | <B>bash</B> | |
10651 | ||
10652 | follows the logical chain of directories when performing commands | |
10653 | which change the current directory. | |
10654 | <DT><B>-T</B> | |
10655 | ||
10656 | <DD> | |
10657 | If set, any traps on <B>DEBUG</B> and <B>RETURN</B> are inherited by shell | |
10658 | functions, command substitutions, and commands executed in a | |
10659 | subshell environment. | |
10660 | The <B>DEBUG</B> and <B>RETURN</B> traps are normally not inherited | |
10661 | in such cases. | |
10662 | <DT><B>--</B> | |
10663 | ||
10664 | <DD> | |
10665 | If no arguments follow this option, then the positional parameters are | |
10666 | unset. Otherwise, the positional parameters are set to the | |
10667 | <I>arg</I>s, even if some of them begin with a | |
10668 | <B>-</B>. | |
10669 | ||
10670 | <DT><B>-</B> | |
10671 | ||
10672 | <DD> | |
10673 | Signal the end of options, cause all remaining <I>arg</I>s to be | |
10674 | assigned to the positional parameters. The | |
10675 | <B>-x</B> | |
10676 | ||
10677 | and | |
10678 | <B>-v</B> | |
10679 | ||
10680 | options are turned off. | |
10681 | If there are no <I>arg</I>s, | |
10682 | the positional parameters remain unchanged. | |
10683 | ||
10684 | </DL> | |
10685 | <P> | |
10686 | ||
10687 | The options are off by default unless otherwise noted. | |
10688 | Using + rather than - causes these options to be turned off. | |
10689 | The options can also be specified as arguments to an invocation of | |
10690 | the shell. | |
10691 | The current set of options may be found in | |
10692 | <B>$-</B>. | |
10693 | ||
10694 | The return status is always true unless an invalid option is encountered. | |
10695 | </DL> | |
10696 | ||
10697 | <DT><B>shift</B> [<I>n</I>]<DD> | |
10698 | The positional parameters from <I>n</I>+1 ... are renamed to | |
10699 | <B>$1</B> | |
10700 | ||
10701 | <B>....</B> | |
10702 | ||
10703 | Parameters represented by the numbers <B>$#</B> | |
10704 | down to <B>$#</B>-<I>n</I>+1 are unset. | |
10705 | <I>n</I> | |
10706 | ||
10707 | must be a non-negative number less than or equal to <B>$#</B>. | |
10708 | If | |
10709 | <I>n</I> | |
10710 | ||
10711 | is 0, no parameters are changed. | |
10712 | If | |
10713 | <I>n </I> | |
10714 | ||
10715 | is not given, it is assumed to be 1. | |
10716 | If | |
10717 | <I>n</I> | |
10718 | ||
10719 | is greater than <B>$#</B>, the positional parameters are not changed. | |
10720 | The return status is greater than zero if | |
10721 | <I>n</I> | |
10722 | ||
10723 | is greater than | |
10724 | <B>$#</B> | |
10725 | ||
10726 | or less than zero; otherwise 0. | |
10727 | <DT><B>shopt</B> [<B>-pqsu</B>] [<B>-o</B>] [<I>optname</I> ...]<DD> | |
10728 | Toggle the values of variables controlling optional shell behavior. | |
10729 | With no options, or with the | |
10730 | <B>-p</B> | |
10731 | ||
10732 | option, a list of all settable options is displayed, with | |
10733 | an indication of whether or not each is set. | |
10734 | The <B>-p</B> option causes output to be displayed in a form that | |
10735 | may be reused as input. | |
10736 | Other options have the following meanings: | |
10737 | <DL COMPACT><DT><DD> | |
10738 | ||
10739 | <DL COMPACT> | |
10740 | <DT><B>-s</B> | |
10741 | ||
10742 | <DD> | |
10743 | Enable (set) each <I>optname</I>. | |
10744 | <DT><B>-u</B> | |
10745 | ||
10746 | <DD> | |
10747 | Disable (unset) each <I>optname</I>. | |
10748 | <DT><B>-q</B> | |
10749 | ||
10750 | <DD> | |
10751 | Suppresses normal output (quiet mode); the return status indicates | |
10752 | whether the <I>optname</I> is set or unset. | |
10753 | If multiple <I>optname</I> arguments are given with | |
10754 | <B>-q</B>, | |
10755 | ||
10756 | the return status is zero if all <I>optnames</I> are enabled; non-zero | |
10757 | otherwise. | |
10758 | <DT><B>-o</B> | |
10759 | ||
10760 | <DD> | |
10761 | Restricts the values of <I>optname</I> to be those defined for the | |
10762 | <B>-o</B> | |
10763 | ||
10764 | option to the | |
10765 | <B>set</B> | |
10766 | ||
10767 | builtin. | |
10768 | ||
10769 | </DL> | |
10770 | <P> | |
10771 | ||
10772 | If either | |
10773 | <B>-s</B> | |
10774 | ||
10775 | or | |
10776 | <B>-u</B> | |
10777 | ||
10778 | is used with no <I>optname</I> arguments, the display is limited to | |
10779 | those options which are set or unset, respectively. | |
10780 | Unless otherwise noted, the <B>shopt</B> options are disabled (unset) | |
10781 | by default. | |
10782 | <P> | |
10783 | ||
10784 | The return status when listing options is zero if all <I>optnames</I> | |
10785 | are enabled, non-zero otherwise. When setting or unsetting options, | |
10786 | the return status is zero unless an <I>optname</I> is not a valid shell | |
10787 | option. | |
10788 | <P> | |
10789 | ||
10790 | The list of <B>shopt</B> options is: | |
10791 | <P> | |
10792 | ||
10793 | ||
10794 | ||
10795 | <DL COMPACT> | |
10796 | <DT><B>autocd</B> | |
10797 | ||
10798 | <DD> | |
10799 | If set, a command name that is the name of a directory is executed as if | |
10800 | it were the argument to the <B>cd</B> command. | |
10801 | This option is only used by interactive shells. | |
10802 | <DT><B>cdable_vars</B> | |
10803 | ||
10804 | <DD> | |
10805 | If set, an argument to the | |
10806 | <B>cd</B> | |
10807 | ||
10808 | builtin command that | |
10809 | is not a directory is assumed to be the name of a variable whose | |
10810 | value is the directory to change to. | |
10811 | <DT><B>cdspell</B> | |
10812 | ||
10813 | <DD> | |
10814 | If set, minor errors in the spelling of a directory component in a | |
10815 | <B>cd</B> | |
10816 | ||
10817 | command will be corrected. | |
10818 | The errors checked for are transposed characters, | |
10819 | a missing character, and one character too many. | |
10820 | If a correction is found, the corrected file name is printed, | |
10821 | and the command proceeds. | |
10822 | This option is only used by interactive shells. | |
10823 | <DT><B>checkhash</B> | |
10824 | ||
10825 | <DD> | |
10826 | If set, <B>bash</B> checks that a command found in the hash | |
10827 | table exists before trying to execute it. If a hashed command no | |
10828 | longer exists, a normal path search is performed. | |
10829 | <DT><B>checkjobs</B> | |
10830 | ||
10831 | <DD> | |
10832 | If set, <B>bash</B> lists the status of any stopped and running jobs before | |
10833 | exiting an interactive shell. If any jobs are running, this causes | |
10834 | the exit to be deferred until a second exit is attempted without an | |
10835 | intervening command (see <B>JOB CONTROL</B> above). The shell always | |
10836 | postpones exiting if any jobs are stopped. | |
10837 | <DT><B>checkwinsize</B> | |
10838 | ||
10839 | <DD> | |
10840 | If set, <B>bash</B> checks the window size after each command | |
10841 | and, if necessary, updates the values of | |
10842 | <FONT SIZE=-1><B>LINES</B> | |
10843 | ||
10844 | </FONT> | |
10845 | and | |
10846 | <FONT SIZE=-1><B>COLUMNS</B>. | |
10847 | ||
10848 | </FONT> | |
10849 | <DT><B>cmdhist</B> | |
10850 | ||
10851 | <DD> | |
10852 | If set, | |
10853 | <B>bash</B> | |
10854 | ||
10855 | attempts to save all lines of a multiple-line | |
10856 | command in the same history entry. This allows | |
10857 | easy re-editing of multi-line commands. | |
10858 | <DT><B>compat31</B> | |
10859 | ||
10860 | <DD> | |
10861 | If set, | |
10862 | <B>bash</B> | |
10863 | ||
10864 | changes its behavior to that of version 3.1 with respect to quoted | |
10865 | arguments to the conditional command's =~ operator. | |
10866 | <DT><B>dirspell</B> | |
10867 | ||
10868 | <DD> | |
10869 | If set, | |
10870 | <B>bash</B> | |
10871 | ||
10872 | attempts spelling correction on directory names during word completion | |
10873 | if the directory name initially supplied does not exist. | |
10874 | <DT><B>dotglob</B> | |
10875 | ||
10876 | <DD> | |
10877 | If set, | |
10878 | <B>bash</B> | |
10879 | ||
10880 | includes filenames beginning with a `.' in the results of pathname | |
10881 | expansion. | |
10882 | <DT><B>execfail</B> | |
10883 | ||
10884 | <DD> | |
10885 | If set, a non-interactive shell will not exit if | |
10886 | it cannot execute the file specified as an argument to the | |
10887 | <B>exec</B> | |
10888 | ||
10889 | builtin command. An interactive shell does not exit if | |
10890 | <B>exec</B> | |
10891 | ||
10892 | fails. | |
10893 | <DT><B>expand_aliases</B> | |
10894 | ||
10895 | <DD> | |
10896 | If set, aliases are expanded as described above under | |
10897 | <FONT SIZE=-1><B>ALIASES</B>. | |
10898 | ||
10899 | </FONT> | |
10900 | This option is enabled by default for interactive shells. | |
10901 | <DT><B>extdebug</B> | |
10902 | ||
10903 | <DD> | |
10904 | If set, behavior intended for use by debuggers is enabled: | |
10905 | <DL COMPACT><DT><DD> | |
10906 | <DL COMPACT> | |
10907 | <DT><B>1.</B> | |
10908 | ||
10909 | <DD> | |
10910 | The <B>-F</B> option to the <B>declare</B> builtin displays the source | |
10911 | file name and line number corresponding to each function name supplied | |
10912 | as an argument. | |
10913 | <DT><B>2.</B> | |
10914 | ||
10915 | <DD> | |
10916 | If the command run by the <B>DEBUG</B> trap returns a non-zero value, the | |
10917 | next command is skipped and not executed. | |
10918 | <DT><B>3.</B> | |
10919 | ||
10920 | <DD> | |
10921 | If the command run by the <B>DEBUG</B> trap returns a value of 2, and the | |
10922 | shell is executing in a subroutine (a shell function or a shell script | |
10923 | executed by the <B>.</B> or <B>source</B> builtins), a call to | |
10924 | <B>return</B> is simulated. | |
10925 | <DT><B>4.</B> | |
10926 | ||
10927 | <DD> | |
10928 | <B>BASH_ARGC</B> and <B>BASH_ARGV</B> are updated as described in their | |
10929 | descriptions above. | |
10930 | <DT><B>5.</B> | |
10931 | ||
10932 | <DD> | |
10933 | Function tracing is enabled: command substitution, shell functions, and | |
10934 | subshells invoked with <B>(</B> <I>command</I> <B>)</B> inherit the | |
10935 | <B>DEBUG</B> and <B>RETURN</B> traps. | |
10936 | <DT><B>6.</B> | |
10937 | ||
10938 | <DD> | |
10939 | Error tracing is enabled: command substitution, shell functions, and | |
10940 | subshells invoked with <B>(</B> <I>command</I> <B>)</B> inherit the | |
10941 | <B>ERROR</B> trap. | |
10942 | </DL></DL> | |
10943 | ||
10944 | <DT><B>extglob</B> | |
10945 | ||
10946 | <DD> | |
10947 | If set, the extended pattern matching features described above under | |
10948 | <B>Pathname Expansion</B> are enabled. | |
10949 | <DT><B>extquote</B> | |
10950 | ||
10951 | <DD> | |
10952 | If set, <B>$</B>aq<I>string</I>aq and <B>$</B>"<I>string</I>" quoting is | |
10953 | performed within <B>${</B><I>parameter</I><B>}</B> expansions | |
10954 | enclosed in double quotes. This option is enabled by default. | |
10955 | <DT><B>failglob</B> | |
10956 | ||
10957 | <DD> | |
10958 | If set, patterns which fail to match filenames during pathname expansion | |
10959 | result in an expansion error. | |
10960 | <DT><B>force_fignore</B> | |
10961 | ||
10962 | <DD> | |
10963 | If set, the suffixes specified by the <B>FIGNORE</B> shell variable | |
10964 | cause words to be ignored when performing word completion even if | |
10965 | the ignored words are the only possible completions. | |
10966 | See | |
10967 | <FONT SIZE=-1><B>SHELL VARIABLES</B></FONT> | |
10968 | above for a description of <B>FIGNORE</B>. | |
10969 | This option is enabled by default. | |
10970 | <DT><B>globstar</B> | |
10971 | ||
10972 | <DD> | |
10973 | If set, the pattern <B>**</B> used in a filename expansion context will | |
10974 | match a files and zero or more directories and subdirectories. | |
10975 | If the pattern is followed by a <B>/</B>, only directories and | |
10976 | subdirectories match. | |
10977 | <DT><B>gnu_errfmt</B> | |
10978 | ||
10979 | <DD> | |
10980 | If set, shell error messages are written in the standard GNU error | |
10981 | message format. | |
10982 | <DT><B>histappend</B> | |
10983 | ||
10984 | <DD> | |
10985 | If set, the history list is appended to the file named by the value | |
10986 | of the | |
10987 | <B>HISTFILE</B> | |
10988 | ||
10989 | variable when the shell exits, rather than overwriting the file. | |
10990 | <DT><B>histreedit</B> | |
10991 | ||
10992 | <DD> | |
10993 | If set, and | |
10994 | <B>readline</B> | |
10995 | ||
10996 | is being used, a user is given the opportunity to re-edit a | |
10997 | failed history substitution. | |
10998 | <DT><B>histverify</B> | |
10999 | ||
11000 | <DD> | |
11001 | If set, and | |
11002 | <B>readline</B> | |
11003 | ||
11004 | is being used, the results of history substitution are not immediately | |
11005 | passed to the shell parser. Instead, the resulting line is loaded into | |
11006 | the <B>readline</B> editing buffer, allowing further modification. | |
11007 | <DT><B>hostcomplete</B> | |
11008 | ||
11009 | <DD> | |
11010 | If set, and | |
11011 | <B>readline</B> | |
11012 | ||
11013 | is being used, <B>bash</B> will attempt to perform hostname completion when a | |
11014 | word containing a <B>@</B> is being completed (see | |
11015 | <B>Completing</B> | |
11016 | ||
11017 | under | |
11018 | <FONT SIZE=-1><B>READLINE</B> | |
11019 | ||
11020 | </FONT> | |
11021 | above). | |
11022 | This is enabled by default. | |
11023 | <DT><B>huponexit</B> | |
11024 | ||
11025 | <DD> | |
11026 | If set, <B>bash</B> will send | |
11027 | <FONT SIZE=-1><B>SIGHUP</B> | |
11028 | ||
11029 | </FONT> | |
11030 | to all jobs when an interactive login shell exits. | |
11031 | <DT><B>interactive_comments</B> | |
11032 | ||
11033 | <DD> | |
11034 | If set, allow a word beginning with | |
11035 | <B>#</B> | |
11036 | ||
11037 | to cause that word and all remaining characters on that | |
11038 | line to be ignored in an interactive shell (see | |
11039 | <FONT SIZE=-1><B>COMMENTS</B> | |
11040 | ||
11041 | </FONT> | |
11042 | above). This option is enabled by default. | |
11043 | <DT><B>lithist</B> | |
11044 | ||
11045 | <DD> | |
11046 | If set, and the | |
11047 | <B>cmdhist</B> | |
11048 | ||
11049 | option is enabled, multi-line commands are saved to the history with | |
11050 | embedded newlines rather than using semicolon separators where possible. | |
11051 | <DT><B>login_shell</B> | |
11052 | ||
11053 | <DD> | |
11054 | The shell sets this option if it is started as a login shell (see | |
11055 | <FONT SIZE=-1><B>INVOCATION</B> | |
11056 | ||
11057 | </FONT> | |
11058 | above). | |
11059 | The value may not be changed. | |
11060 | <DT><B>mailwarn</B> | |
11061 | ||
11062 | <DD> | |
11063 | If set, and a file that <B>bash</B> is checking for mail has been | |
11064 | accessed since the last time it was checked, the message ``The mail in | |
11065 | <I>mailfile</I> has been read'' is displayed. | |
11066 | <DT><B>no_empty_cmd_completion</B> | |
11067 | ||
11068 | <DD> | |
11069 | If set, and | |
11070 | <B>readline</B> | |
11071 | ||
11072 | is being used, | |
11073 | <B>bash</B> | |
11074 | ||
11075 | will not attempt to search the <B>PATH</B> for possible completions when | |
11076 | completion is attempted on an empty line. | |
11077 | <DT><B>nocaseglob</B> | |
11078 | ||
11079 | <DD> | |
11080 | If set, | |
11081 | <B>bash</B> | |
11082 | ||
11083 | matches filenames in a case-insensitive fashion when performing pathname | |
11084 | expansion (see | |
11085 | <B>Pathname Expansion</B> | |
11086 | ||
11087 | above). | |
11088 | <DT><B>nocasematch</B> | |
11089 | ||
11090 | <DD> | |
11091 | If set, | |
11092 | <B>bash</B> | |
11093 | ||
11094 | matches patterns in a case-insensitive fashion when performing matching | |
11095 | while executing <B>case</B> or <B>[[</B> conditional commands. | |
11096 | <DT><B>nullglob</B> | |
11097 | ||
11098 | <DD> | |
11099 | If set, | |
11100 | <B>bash</B> | |
11101 | ||
11102 | allows patterns which match no | |
11103 | files (see | |
11104 | <B>Pathname Expansion</B> | |
11105 | ||
11106 | above) | |
11107 | to expand to a null string, rather than themselves. | |
11108 | <DT><B>progcomp</B> | |
11109 | ||
11110 | <DD> | |
11111 | If set, the programmable completion facilities (see | |
11112 | <B>Programmable Completion</B> above) are enabled. | |
11113 | This option is enabled by default. | |
11114 | <DT><B>promptvars</B> | |
11115 | ||
11116 | <DD> | |
11117 | If set, prompt strings undergo | |
11118 | parameter expansion, command substitution, arithmetic | |
11119 | expansion, and quote removal after being expanded as described in | |
11120 | <FONT SIZE=-1><B>PROMPTING</B> | |
11121 | ||
11122 | </FONT> | |
11123 | above. This option is enabled by default. | |
11124 | <DT><B>restricted_shell</B> | |
11125 | ||
11126 | <DD> | |
11127 | The shell sets this option if it is started in restricted mode (see | |
11128 | <FONT SIZE=-1><B>RESTRICTED SHELL</B> | |
11129 | ||
11130 | </FONT> | |
11131 | below). | |
11132 | The value may not be changed. | |
11133 | This is not reset when the startup files are executed, allowing | |
11134 | the startup files to discover whether or not a shell is restricted. | |
11135 | <DT><B>shift_verbose</B> | |
11136 | ||
11137 | <DD> | |
11138 | If set, the | |
11139 | <B>shift</B> | |
11140 | ||
11141 | builtin prints an error message when the shift count exceeds the | |
11142 | number of positional parameters. | |
11143 | <DT><B>sourcepath</B> | |
11144 | ||
11145 | <DD> | |
11146 | If set, the | |
11147 | <B>source</B> (<B>.</B>) builtin uses the value of | |
11148 | <FONT SIZE=-1><B>PATH</B> | |
11149 | ||
11150 | </FONT> | |
11151 | to find the directory containing the file supplied as an argument. | |
11152 | This option is enabled by default. | |
11153 | <DT><B>xpg_echo</B> | |
11154 | ||
11155 | <DD> | |
11156 | If set, the <B>echo</B> builtin expands backslash-escape sequences | |
11157 | by default. | |
11158 | </DL></DL> | |
11159 | ||
11160 | <DT><B>suspend</B> [<B>-f</B>]<DD> | |
11161 | Suspend the execution of this shell until it receives a | |
11162 | <FONT SIZE=-1><B>SIGCONT</B> | |
11163 | ||
11164 | </FONT> | |
11165 | signal. A login shell cannot be suspended; the | |
11166 | <B>-f</B> | |
11167 | ||
11168 | option can be used to override this and force the suspension. | |
11169 | The return status is 0 unless the shell is a login shell and | |
11170 | <B>-f</B> | |
11171 | ||
11172 | is not supplied, or if job control is not enabled. | |
11173 | <DT><B>test</B> <I>expr</I><DD> | |
11174 | ||
11175 | <DT><B>[</B> <I>expr</I> <B>]</B><DD> | |
11176 | Return a status of 0 or 1 depending on | |
11177 | the evaluation of the conditional expression | |
11178 | <I>expr</I>. | |
11179 | ||
11180 | Each operator and operand must be a separate argument. | |
11181 | Expressions are composed of the primaries described above under | |
11182 | <FONT SIZE=-1><B>CONDITIONAL EXPRESSIONS</B>. | |
11183 | ||
11184 | </FONT> | |
11185 | <B>test</B> does not accept any options, nor does it accept and ignore | |
11186 | an argument of <B>--</B> as signifying the end of options. | |
11187 | <P> | |
11188 | ||
11189 | ||
11190 | Expressions may be combined using the following operators, listed | |
11191 | in decreasing order of precedence. | |
11192 | The evaluation depends on the number of arguments; see below. | |
11193 | <DL COMPACT><DT><DD> | |
11194 | ||
11195 | <DL COMPACT> | |
11196 | <DT><B>! </B><I>expr</I> | |
11197 | ||
11198 | <DD> | |
11199 | True if | |
11200 | <I>expr</I> | |
11201 | ||
11202 | is false. | |
11203 | <DT><B>( </B><I>expr</I> ) | |
11204 | ||
11205 | <DD> | |
11206 | Returns the value of <I>expr</I>. | |
11207 | This may be used to override the normal precedence of operators. | |
11208 | <DT><I>expr1</I> -<B>a</B> <I>expr2</I><DD> | |
11209 | True if both | |
11210 | <I>expr1</I> | |
11211 | ||
11212 | and | |
11213 | <I>expr2</I> | |
11214 | ||
11215 | are true. | |
11216 | <DT><I>expr1</I> -<B>o</B> <I>expr2</I><DD> | |
11217 | True if either | |
11218 | <I>expr1</I> | |
11219 | ||
11220 | or | |
11221 | <I>expr2</I> | |
11222 | ||
11223 | is true. | |
11224 | ||
11225 | </DL> | |
11226 | <P> | |
11227 | ||
11228 | <B>test</B> and <B>[</B> evaluate conditional | |
11229 | expressions using a set of rules based on the number of arguments. | |
11230 | <P> | |
11231 | ||
11232 | ||
11233 | ||
11234 | <DL COMPACT> | |
11235 | <DT>0 arguments<DD> | |
11236 | The expression is false. | |
11237 | <DT>1 argument<DD> | |
11238 | The expression is true if and only if the argument is not null. | |
11239 | <DT>2 arguments<DD> | |
11240 | If the first argument is <B>!</B>, the expression is true if and | |
11241 | only if the second argument is null. | |
11242 | If the first argument is one of the unary conditional operators listed above | |
11243 | under | |
11244 | <FONT SIZE=-1><B>CONDITIONAL EXPRESSIONS</B>, | |
11245 | ||
11246 | </FONT> | |
11247 | the expression is true if the unary test is true. | |
11248 | If the first argument is not a valid unary conditional operator, the expression | |
11249 | is false. | |
11250 | <DT>3 arguments<DD> | |
11251 | If the second argument is one of the binary conditional operators listed above | |
11252 | under | |
11253 | <FONT SIZE=-1><B>CONDITIONAL EXPRESSIONS</B>, | |
11254 | ||
11255 | </FONT> | |
11256 | the result of the expression is the result of the binary test using | |
11257 | the first and third arguments as operands. | |
11258 | The <B>-a</B> and <B>-o</B> operators are considered binary operators | |
11259 | when there are three arguments. | |
11260 | If the first argument is <B>!</B>, the value is the negation of | |
11261 | the two-argument test using the second and third arguments. | |
11262 | If the first argument is exactly <B>(</B> and the third argument is | |
11263 | exactly <B>)</B>, the result is the one-argument test of the second | |
11264 | argument. | |
11265 | Otherwise, the expression is false. | |
11266 | <DT>4 arguments<DD> | |
11267 | If the first argument is <B>!</B>, the result is the negation of | |
11268 | the three-argument expression composed of the remaining arguments. | |
11269 | Otherwise, the expression is parsed and evaluated according to | |
11270 | precedence using the rules listed above. | |
11271 | <DT>5 or more arguments<DD> | |
11272 | The expression is parsed and evaluated according to precedence | |
11273 | using the rules listed above. | |
11274 | </DL></DL> | |
11275 | ||
11276 | ||
11277 | <DT><B>times</B> | |
11278 | ||
11279 | <DD> | |
11280 | Print the accumulated user and system times for the shell and | |
11281 | for processes run from the shell. The return status is 0. | |
11282 | <DT><B>trap</B> [<B>-lp</B>] [[<I>arg</I>] <I>sigspec</I> ...]<DD> | |
11283 | The command | |
11284 | <I>arg</I> | |
11285 | ||
11286 | is to be read and executed when the shell receives | |
11287 | signal(s) | |
11288 | <I>sigspec</I>. | |
11289 | ||
11290 | If | |
11291 | <I>arg</I> | |
11292 | ||
11293 | is absent (and there is a single <I>sigspec</I>) or | |
11294 | <B>-</B>, | |
11295 | ||
11296 | each specified signal is | |
11297 | reset to its original disposition (the value it had | |
11298 | upon entrance to the shell). | |
11299 | If | |
11300 | <I>arg</I> | |
11301 | ||
11302 | is the null string the signal specified by each | |
11303 | <I>sigspec</I> | |
11304 | ||
11305 | is ignored by the shell and by the commands it invokes. | |
11306 | If | |
11307 | <I>arg</I> | |
11308 | ||
11309 | is not present and | |
11310 | <B>-p</B> | |
11311 | ||
11312 | has been supplied, then the trap commands associated with each | |
11313 | <I>sigspec</I> | |
11314 | ||
11315 | are displayed. | |
11316 | If no arguments are supplied or if only | |
11317 | <B>-p</B> | |
11318 | ||
11319 | is given, | |
11320 | <B>trap</B> | |
11321 | ||
11322 | prints the list of commands associated with each signal. | |
11323 | The | |
11324 | <B>-l</B> | |
11325 | ||
11326 | option causes the shell to print a list of signal names and | |
11327 | their corresponding numbers. | |
11328 | Each | |
11329 | <I>sigspec</I> | |
11330 | ||
11331 | is either | |
11332 | a signal name defined in <<I>signal.h</I>>, or a signal number. | |
11333 | Signal names are case insensitive and the SIG prefix is optional. | |
11334 | If a | |
11335 | <I>sigspec</I> | |
11336 | ||
11337 | is | |
11338 | <FONT SIZE=-1><B>EXIT</B> | |
11339 | ||
11340 | </FONT> | |
11341 | (0) the command | |
11342 | <I>arg</I> | |
11343 | ||
11344 | is executed on exit from the shell. | |
11345 | If a | |
11346 | <I>sigspec</I> | |
11347 | ||
11348 | is | |
11349 | <FONT SIZE=-1><B>DEBUG</B>, | |
11350 | ||
11351 | </FONT> | |
11352 | the command | |
11353 | <I>arg</I> | |
11354 | ||
11355 | is executed before every <I>simple command</I>, <I>for</I> command, | |
11356 | <I>case</I> command, <I>select</I> command, every arithmetic <I>for</I> | |
11357 | command, and before the first command executes in a shell function (see | |
11358 | <FONT SIZE=-1><B>SHELL GRAMMAR</B> | |
11359 | ||
11360 | </FONT> | |
11361 | above). | |
11362 | Refer to the description of the <B>extdebug</B> option to the | |
11363 | <B>shopt</B> builtin for details of its effect on the <B>DEBUG</B> trap. | |
11364 | If a | |
11365 | <I>sigspec</I> | |
11366 | ||
11367 | is | |
11368 | <FONT SIZE=-1><B>ERR</B>, | |
11369 | ||
11370 | </FONT> | |
11371 | the command | |
11372 | <I>arg</I> | |
11373 | ||
11374 | is executed whenever a simple command has a non-zero exit status, | |
11375 | subject to the following conditions. | |
11376 | The | |
11377 | <FONT SIZE=-1><B>ERR</B> | |
11378 | ||
11379 | </FONT> | |
11380 | trap is not executed if the failed | |
11381 | command is part of the command list immediately following a | |
11382 | <B>while</B> | |
11383 | ||
11384 | or | |
11385 | <B>until</B> | |
11386 | ||
11387 | keyword, | |
11388 | part of the test in an | |
11389 | <I>if</I> | |
11390 | ||
11391 | statement, part of a command executed in a | |
11392 | <B>&&</B> | |
11393 | ||
11394 | or | |
11395 | <B>||</B> | |
11396 | ||
11397 | list, or if the command's return value is | |
11398 | being inverted via | |
11399 | <B>!</B>. | |
11400 | ||
11401 | These are the same conditions obeyed by the <B>errexit</B> option. | |
11402 | If a | |
11403 | <I>sigspec</I> | |
11404 | ||
11405 | is | |
11406 | <FONT SIZE=-1><B>RETURN</B>, | |
11407 | ||
11408 | </FONT> | |
11409 | the command | |
11410 | <I>arg</I> | |
11411 | ||
11412 | is executed each time a shell function or a script executed with the | |
11413 | <B>.</B> or <B>source</B> builtins finishes executing. | |
11414 | Signals ignored upon entry to the shell cannot be trapped or reset. | |
11415 | Trapped signals that are not being ignored are reset to their original | |
11416 | values in a child process when it is created. | |
11417 | The return status is false if any | |
11418 | <I>sigspec</I> | |
11419 | ||
11420 | is invalid; otherwise | |
11421 | <B>trap</B> | |
11422 | ||
11423 | returns true. | |
11424 | <DT><B>type</B> [<B>-aftpP</B>] <I>name</I> [<I>name</I> ...]<DD> | |
11425 | With no options, | |
11426 | indicate how each | |
11427 | <I>name</I> | |
11428 | ||
11429 | would be interpreted if used as a command name. | |
11430 | If the | |
11431 | <B>-t</B> | |
11432 | ||
11433 | option is used, | |
11434 | <B>type</B> | |
11435 | ||
11436 | prints a string which is one of | |
11437 | <I>alias</I>, | |
11438 | ||
11439 | <I>keyword</I>, | |
11440 | ||
11441 | <I>function</I>, | |
11442 | ||
11443 | <I>builtin</I>, | |
11444 | ||
11445 | or | |
11446 | <I>file </I> | |
11447 | ||
11448 | if | |
11449 | <I>name</I> | |
11450 | ||
11451 | is an alias, shell reserved word, function, builtin, or disk file, | |
11452 | respectively. | |
11453 | If the | |
11454 | <I>name</I> | |
11455 | ||
11456 | is not found, then nothing is printed, and an exit status of false | |
11457 | is returned. | |
11458 | If the | |
11459 | <B>-p</B> | |
11460 | ||
11461 | option is used, | |
11462 | <B>type</B> | |
11463 | ||
11464 | either returns the name of the disk file | |
11465 | that would be executed if | |
11466 | <I>name</I> | |
11467 | ||
11468 | were specified as a command name, | |
11469 | or nothing if | |
11470 | <TT>type -t name</TT> | |
11471 | ||
11472 | would not return | |
11473 | <I>file</I>. | |
11474 | ||
11475 | The | |
11476 | <B>-P</B> | |
11477 | ||
11478 | option forces a | |
11479 | <FONT SIZE=-1><B>PATH</B> | |
11480 | ||
11481 | </FONT> | |
11482 | search for each <I>name</I>, even if | |
11483 | <TT>type -t name</TT> | |
11484 | ||
11485 | would not return | |
11486 | <I>file</I>. | |
11487 | ||
11488 | If a command is hashed, | |
11489 | <B>-p</B> | |
11490 | ||
11491 | and | |
11492 | <B>-P</B> | |
11493 | ||
11494 | print the hashed value, not necessarily the file that appears | |
11495 | first in | |
11496 | <FONT SIZE=-1><B>PATH</B>. | |
11497 | ||
11498 | </FONT> | |
11499 | If the | |
11500 | <B>-a</B> | |
11501 | ||
11502 | option is used, | |
11503 | <B>type</B> | |
11504 | ||
11505 | prints all of the places that contain | |
11506 | an executable named | |
11507 | <I>name</I>. | |
11508 | ||
11509 | This includes aliases and functions, | |
11510 | if and only if the | |
11511 | <B>-p</B> | |
11512 | ||
11513 | option is not also used. | |
11514 | The table of hashed commands is not consulted | |
11515 | when using | |
11516 | <B>-a</B>. | |
11517 | ||
11518 | The | |
11519 | <B>-f</B> | |
11520 | ||
11521 | option suppresses shell function lookup, as with the <B>command</B> builtin. | |
11522 | <B>type</B> | |
11523 | ||
11524 | returns true if all of the arguments are found, false if | |
11525 | any are not found. | |
11526 | <DT><B>ulimit</B> [<B>-HSTabcdefilmnpqrstuvx</B> [<I>limit</I>]]<DD> | |
11527 | Provides control over the resources available to the shell and to | |
11528 | processes started by it, on systems that allow such control. | |
11529 | The <B>-H</B> and <B>-S</B> options specify that the hard or soft limit is | |
11530 | set for the given resource. | |
11531 | A hard limit cannot be increased by a non-root user once it is set; | |
11532 | a soft limit may be increased up to the value of the hard limit. | |
11533 | If neither <B>-H</B> nor <B>-S</B> is specified, both the soft and hard | |
11534 | limits are set. | |
11535 | The value of | |
11536 | <I>limit</I> | |
11537 | ||
11538 | can be a number in the unit specified for the resource | |
11539 | or one of the special values | |
11540 | <B>hard</B>, | |
11541 | ||
11542 | <B>soft</B>, | |
11543 | ||
11544 | or | |
11545 | <B>unlimited</B>, | |
11546 | ||
11547 | which stand for the current hard limit, the current soft limit, and | |
11548 | no limit, respectively. | |
11549 | If | |
11550 | <I>limit</I> | |
11551 | ||
11552 | is omitted, the current value of the soft limit of the resource is | |
11553 | printed, unless the <B>-H</B> option is given. When more than one | |
11554 | resource is specified, the limit name and unit are printed before the value. | |
11555 | Other options are interpreted as follows: | |
11556 | <DL COMPACT><DT><DD> | |
11557 | ||
11558 | <DL COMPACT> | |
11559 | <DT><B>-a</B> | |
11560 | ||
11561 | <DD> | |
11562 | All current limits are reported | |
11563 | <DT><B>-b</B> | |
11564 | ||
11565 | <DD> | |
11566 | The maximum socket buffer size | |
11567 | <DT><B>-c</B> | |
11568 | ||
11569 | <DD> | |
11570 | The maximum size of core files created | |
11571 | <DT><B>-d</B> | |
11572 | ||
11573 | <DD> | |
11574 | The maximum size of a process's data segment | |
11575 | <DT><B>-e</B> | |
11576 | ||
11577 | <DD> | |
11578 | The maximum scheduling priority ("nice") | |
11579 | <DT><B>-f</B> | |
11580 | ||
11581 | <DD> | |
11582 | The maximum size of files written by the shell and its children | |
11583 | <DT><B>-i</B> | |
11584 | ||
11585 | <DD> | |
11586 | The maximum number of pending signals | |
11587 | <DT><B>-l</B> | |
11588 | ||
11589 | <DD> | |
11590 | The maximum size that may be locked into memory | |
11591 | <DT><B>-m</B> | |
11592 | ||
11593 | <DD> | |
11594 | The maximum resident set size | |
11595 | <DT><B>-n</B> | |
11596 | ||
11597 | <DD> | |
11598 | The maximum number of open file descriptors (most systems do not | |
11599 | allow this value to be set) | |
11600 | <DT><B>-p</B> | |
11601 | ||
11602 | <DD> | |
11603 | The pipe size in 512-byte blocks (this may not be set) | |
11604 | <DT><B>-q</B> | |
11605 | ||
11606 | <DD> | |
11607 | The maximum number of bytes in POSIX message queues | |
11608 | <DT><B>-r</B> | |
11609 | ||
11610 | <DD> | |
11611 | The maximum real-time scheduling priority | |
11612 | <DT><B>-s</B> | |
11613 | ||
11614 | <DD> | |
11615 | The maximum stack size | |
11616 | <DT><B>-t</B> | |
11617 | ||
11618 | <DD> | |
11619 | The maximum amount of cpu time in seconds | |
11620 | <DT><B>-u</B> | |
11621 | ||
11622 | <DD> | |
11623 | The maximum number of processes available to a single user | |
11624 | <DT><B>-v</B> | |
11625 | ||
11626 | <DD> | |
11627 | The maximum amount of virtual memory available to the shell | |
11628 | <DT><B>-x</B> | |
11629 | ||
11630 | <DD> | |
11631 | The maximum number of file locks | |
11632 | <DT><B>-T</B> | |
11633 | ||
11634 | <DD> | |
11635 | The maximum number of threads | |
11636 | ||
11637 | </DL> | |
11638 | <P> | |
11639 | ||
11640 | If | |
11641 | <I>limit</I> | |
11642 | ||
11643 | is given, it is the new value of the specified resource (the | |
11644 | <B>-a</B> | |
11645 | ||
11646 | option is display only). | |
11647 | If no option is given, then | |
11648 | <B>-f</B> | |
11649 | ||
11650 | is assumed. Values are in 1024-byte increments, except for | |
11651 | <B>-t</B>, | |
11652 | ||
11653 | which is in seconds, | |
11654 | <B>-p</B>, | |
11655 | ||
11656 | which is in units of 512-byte blocks, | |
11657 | and | |
11658 | <B>-T</B>, | |
11659 | ||
11660 | <B>-b</B>, | |
11661 | ||
11662 | <B>-n</B>, | |
11663 | ||
11664 | and | |
11665 | <B>-u</B>, | |
11666 | ||
11667 | which are unscaled values. | |
11668 | The return status is 0 unless an invalid option or argument is supplied, | |
11669 | or an error occurs while setting a new limit. | |
11670 | </DL> | |
11671 | ||
11672 | <DT><B>umask</B> [<B>-p</B>] [<B>-S</B>] [<I>mode</I>]<DD> | |
11673 | The user file-creation mask is set to | |
11674 | <I>mode</I>. | |
11675 | ||
11676 | If | |
11677 | <I>mode</I> | |
11678 | ||
11679 | begins with a digit, it | |
11680 | is interpreted as an octal number; otherwise | |
11681 | it is interpreted as a symbolic mode mask similar | |
11682 | to that accepted by | |
11683 | <I>chmod</I>(1). | |
11684 | ||
11685 | If | |
11686 | <I>mode</I> | |
11687 | ||
11688 | is omitted, the current value of the mask is printed. | |
11689 | The | |
11690 | <B>-S</B> | |
11691 | ||
11692 | option causes the mask to be printed in symbolic form; the | |
11693 | default output is an octal number. | |
11694 | If the | |
11695 | <B>-p</B> | |
11696 | ||
11697 | option is supplied, and | |
11698 | <I>mode</I> | |
11699 | ||
11700 | is omitted, the output is in a form that may be reused as input. | |
11701 | The return status is 0 if the mode was successfully changed or if | |
11702 | no <I>mode</I> argument was supplied, and false otherwise. | |
11703 | <DT><B>unalias</B> [-<B>a</B>] [<I>name</I> ...]<DD> | |
11704 | Remove each <I>name</I> from the list of defined aliases. If | |
11705 | <B>-a</B> | |
11706 | ||
11707 | is supplied, all alias definitions are removed. The return | |
11708 | value is true unless a supplied | |
11709 | <I>name</I> | |
11710 | ||
11711 | is not a defined alias. | |
11712 | <DT><B>unset</B> [-<B>fv</B>] [<I>name</I> ...]<DD> | |
11713 | For each | |
11714 | <I>name</I>, | |
11715 | ||
11716 | remove the corresponding variable or function. | |
11717 | If no options are supplied, or the | |
11718 | <B>-v</B> | |
11719 | ||
11720 | option is given, each | |
11721 | <I>name</I> | |
11722 | ||
11723 | refers to a shell variable. | |
11724 | Read-only variables may not be unset. | |
11725 | If | |
11726 | <B>-f</B> | |
11727 | ||
11728 | is specified, each | |
11729 | <I>name</I> | |
11730 | ||
11731 | refers to a shell function, and the function definition | |
11732 | is removed. | |
11733 | Each unset variable or function is removed from the environment | |
11734 | passed to subsequent commands. | |
11735 | If any of | |
11736 | <FONT SIZE=-1><B>RANDOM</B>, | |
11737 | ||
11738 | </FONT> | |
11739 | <FONT SIZE=-1><B>SECONDS</B>, | |
11740 | ||
11741 | </FONT> | |
11742 | <FONT SIZE=-1><B>LINENO</B>, | |
11743 | ||
11744 | </FONT> | |
11745 | <FONT SIZE=-1><B>HISTCMD</B>, | |
11746 | ||
11747 | </FONT> | |
11748 | <FONT SIZE=-1><B>FUNCNAME</B>, | |
11749 | ||
11750 | </FONT> | |
11751 | <FONT SIZE=-1><B>GROUPS</B>, | |
11752 | ||
11753 | </FONT> | |
11754 | or | |
11755 | <FONT SIZE=-1><B>DIRSTACK</B> | |
11756 | ||
11757 | </FONT> | |
11758 | are unset, they lose their special properties, even if they are | |
11759 | subsequently reset. The exit status is true unless a | |
11760 | <I>name</I> | |
11761 | ||
11762 | is readonly. | |
11763 | <DT><B>wait</B> [<I>n ...</I>]<DD> | |
11764 | Wait for each specified process and return its termination status. | |
11765 | Each | |
11766 | <I>n</I> | |
11767 | ||
11768 | may be a process | |
11769 | ID or a job specification; if a job spec is given, all processes | |
11770 | in that job's pipeline are waited for. If | |
11771 | <I>n</I> | |
11772 | ||
11773 | is not given, all currently active child processes | |
11774 | are waited for, and the return status is zero. If | |
11775 | <I>n</I> | |
11776 | ||
11777 | specifies a non-existent process or job, the return status is | |
11778 | 127. Otherwise, the return status is the exit status of the last | |
11779 | process or job waited for. | |
11780 | ||
11781 | ||
11782 | </DL> | |
11783 | <A NAME="lbDC"> </A> | |
11784 | <H3>RESTRICTED SHELL</H3> | |
11785 | ||
11786 | ||
11787 | ||
11788 | <P> | |
11789 | ||
11790 | If | |
11791 | <B>bash</B> | |
11792 | ||
11793 | is started with the name | |
11794 | <B>rbash</B>, | |
11795 | ||
11796 | or the | |
11797 | <B>-r</B> | |
11798 | ||
11799 | option is supplied at invocation, | |
11800 | the shell becomes restricted. | |
11801 | A restricted shell is used to | |
11802 | set up an environment more controlled than the standard shell. | |
11803 | It behaves identically to | |
11804 | <B>bash</B> | |
11805 | ||
11806 | with the exception that the following are disallowed or not performed: | |
11807 | <DL COMPACT> | |
11808 | <DT>*<DD> | |
11809 | changing directories with <B>cd</B> | |
11810 | <DT>*<DD> | |
11811 | setting or unsetting the values of | |
11812 | <B>SHELL</B>, | |
11813 | ||
11814 | <B>PATH</B>, | |
11815 | ||
11816 | <B>ENV</B>, | |
11817 | ||
11818 | or | |
11819 | <B>BASH_ENV</B> | |
11820 | ||
11821 | <DT>*<DD> | |
11822 | specifying command names containing | |
11823 | <B>/</B> | |
11824 | ||
11825 | <DT>*<DD> | |
11826 | specifying a file name containing a | |
11827 | <B>/</B> | |
11828 | ||
11829 | as an argument to the | |
11830 | <B>.</B> | |
11831 | ||
11832 | builtin command | |
11833 | <DT>*<DD> | |
11834 | Specifying a filename containing a slash as an argument to the | |
11835 | <B>-p</B> | |
11836 | ||
11837 | option to the | |
11838 | <B>hash</B> | |
11839 | ||
11840 | builtin command | |
11841 | <DT>*<DD> | |
11842 | importing function definitions from the shell environment at startup | |
11843 | <DT>*<DD> | |
11844 | parsing the value of <B>SHELLOPTS</B> from the shell environment at startup | |
11845 | <DT>*<DD> | |
11846 | redirecting output using the >, >|, <>, >&, &>, and >> redirection operators | |
11847 | <DT>*<DD> | |
11848 | using the | |
11849 | <B>exec</B> | |
11850 | ||
11851 | builtin command to replace the shell with another command | |
11852 | <DT>*<DD> | |
11853 | adding or deleting builtin commands with the | |
11854 | <B>-f</B> | |
11855 | ||
11856 | and | |
11857 | <B>-d</B> | |
11858 | ||
11859 | options to the | |
11860 | <B>enable</B> | |
11861 | ||
11862 | builtin command | |
11863 | <DT>*<DD> | |
11864 | Using the <B>enable</B> builtin command to enable disabled shell builtins | |
11865 | <DT>*<DD> | |
11866 | specifying the | |
11867 | <B>-p</B> | |
11868 | ||
11869 | option to the | |
11870 | <B>command</B> | |
11871 | ||
11872 | builtin command | |
11873 | <DT>*<DD> | |
11874 | turning off restricted mode with | |
11875 | <B>set +r</B> or <B>set +o restricted</B>. | |
11876 | </DL> | |
11877 | <P> | |
11878 | ||
11879 | These restrictions are enforced after any startup files are read. | |
11880 | <P> | |
11881 | ||
11882 | ||
11883 | When a command that is found to be a shell script is executed | |
11884 | (see | |
11885 | <FONT SIZE=-1><B>COMMAND EXECUTION</B> | |
11886 | ||
11887 | </FONT> | |
11888 | ||
11889 | above), | |
11890 | ||
11891 | <B>rbash</B> | |
11892 | ||
11893 | turns off any restrictions in the shell spawned to execute the | |
11894 | script. | |
11895 | ||
11896 | ||
11897 | <A NAME="lbDD"> </A> | |
11898 | <H3>SEE ALSO</H3> | |
11899 | ||
11900 | ||
11901 | <DL COMPACT> | |
11902 | <DT><I>Bash Reference Manual</I>, Brian Fox and Chet Ramey<DD> | |
11903 | <DT><I>The Gnu Readline Library</I>, Brian Fox and Chet Ramey<DD> | |
11904 | <DT><I>The Gnu History Library</I>, Brian Fox and Chet Ramey<DD> | |
11905 | <DT><I>Portable Operating System Interface (POSIX) Part 2: Shell and Utilities</I>, IEEE<DD> | |
11906 | <DT><I>sh</I>(1), <I>ksh</I>(1), <I>csh</I>(1)<DD> | |
11907 | <DT><I>emacs</I>(1), <I>vi</I>(1)<DD> | |
11908 | <DT><I>readline</I>(3)<DD> | |
11909 | ||
11910 | </DL> | |
11911 | <A NAME="lbDE"> </A> | |
11912 | <H3>FILES</H3> | |
11913 | ||
11914 | ||
11915 | <DL COMPACT> | |
11916 | <DT> | |
11917 | <A HREF="file:/bin/bash"><I>/bin/bash</I></A> | |
11918 | ||
11919 | <DD> | |
11920 | The <B>bash</B> executable | |
11921 | <DT> | |
11922 | <A HREF="file:/etc/profile"><I>/etc/profile</I></A> | |
11923 | ||
11924 | <DD> | |
11925 | The systemwide initialization file, executed for login shells | |
11926 | <DT> | |
11927 | <A HREF="file:~/.bash_profile"><I>~/.bash_profile</I></A> | |
11928 | ||
11929 | <DD> | |
11930 | The personal initialization file, executed for login shells | |
11931 | <DT> | |
11932 | <A HREF="file:~/.bashrc"><I>~/.bashrc</I></A> | |
11933 | ||
11934 | <DD> | |
11935 | The individual per-interactive-shell startup file | |
11936 | <DT> | |
11937 | <A HREF="file:~/.bash_logout"><I>~/.bash_logout</I></A> | |
11938 | ||
11939 | <DD> | |
11940 | The individual login shell cleanup file, executed when a login shell exits | |
11941 | <DT> | |
11942 | <A HREF="file:~/.inputrc"><I>~/.inputrc</I></A> | |
11943 | ||
11944 | <DD> | |
11945 | Individual <I>readline</I> initialization file | |
11946 | ||
11947 | </DL> | |
11948 | <A NAME="lbDF"> </A> | |
11949 | <H3>AUTHORS</H3> | |
11950 | ||
11951 | Brian Fox, Free Software Foundation | |
11952 | <BR> | |
11953 | ||
11954 | <A HREF="mailto:bfox@gnu.org">bfox@gnu.org</A> | |
11955 | <P> | |
11956 | ||
11957 | Chet Ramey, Case Western Reserve University | |
11958 | <BR> | |
11959 | ||
11960 | <A HREF="mailto:chet@po.cwru.edu">chet@po.cwru.edu</A> | |
11961 | <A NAME="lbDG"> </A> | |
11962 | <H3>BUG REPORTS</H3> | |
11963 | ||
11964 | If you find a bug in | |
11965 | <B>bash,</B> | |
11966 | ||
11967 | you should report it. But first, you should | |
11968 | make sure that it really is a bug, and that it appears in the latest | |
11969 | version of | |
11970 | <B>bash</B>. | |
11971 | ||
11972 | The latest version is always available from | |
11973 | <I><A HREF="ftp://ftp.gnu.org/pub/bash/">ftp://ftp.gnu.org/pub/bash/</A></I>. | |
11974 | <P> | |
11975 | ||
11976 | Once you have determined that a bug actually exists, use the | |
11977 | <I>bashbug</I> | |
11978 | ||
11979 | command to submit a bug report. | |
11980 | If you have a fix, you are encouraged to mail that as well! | |
11981 | Suggestions and `philosophical' bug reports may be mailed | |
11982 | to <I><A HREF="mailto:bug-bash@gnu.org">bug-bash@gnu.org</A></I> or posted to the Usenet | |
11983 | newsgroup | |
11984 | <A HREF="news:gnu.bash.bug">gnu.bash.bug</A>. | |
11985 | ||
11986 | <P> | |
11987 | ||
11988 | ALL bug reports should include: | |
11989 | <P> | |
11990 | ||
11991 | ||
11992 | <DL COMPACT> | |
11993 | <DT>The version number of <B>bash</B><DD> | |
11994 | <DT>The hardware and operating system<DD> | |
11995 | <DT>The compiler used to compile<DD> | |
11996 | <DT>A description of the bug behaviour<DD> | |
11997 | <DT>A short script or `recipe' which exercises the bug<DD> | |
11998 | ||
11999 | </DL> | |
12000 | <P> | |
12001 | ||
12002 | <I>bashbug</I> | |
12003 | ||
12004 | inserts the first three items automatically into the template | |
12005 | it provides for filing a bug report. | |
12006 | <P> | |
12007 | ||
12008 | Comments and bug reports concerning | |
12009 | this manual page should be directed to | |
12010 | <I><A HREF="mailto:chet@po.cwru.edu">chet@po.cwru.edu</A></I>. | |
12011 | ||
12012 | <A NAME="lbDH"> </A> | |
12013 | <H3>BUGS</H3> | |
12014 | ||
12015 | <P> | |
12016 | ||
12017 | It's too big and too slow. | |
12018 | <P> | |
12019 | ||
12020 | There are some subtle differences between | |
12021 | <B>bash</B> | |
12022 | ||
12023 | and traditional versions of | |
12024 | <B>sh</B>, | |
12025 | ||
12026 | mostly because of the | |
12027 | <FONT SIZE=-1><B>POSIX</B> | |
12028 | ||
12029 | </FONT> | |
12030 | specification. | |
12031 | <P> | |
12032 | ||
12033 | Aliases are confusing in some uses. | |
12034 | <P> | |
12035 | ||
12036 | Shell builtin commands and functions are not stoppable/restartable. | |
12037 | <P> | |
12038 | ||
12039 | Compound commands and command sequences of the form `a ; b ; c' | |
12040 | are not handled gracefully when process suspension is attempted. | |
12041 | When a process is stopped, the shell immediately executes the next | |
12042 | command in the sequence. | |
12043 | It suffices to place the sequence of commands between | |
12044 | parentheses to force it into a subshell, which may be stopped as | |
12045 | a unit. | |
12046 | <P> | |
12047 | ||
12048 | Array variables may not (yet) be exported. | |
12049 | <P> | |
12050 | ||
12051 | There may be only one active coprocess at a time. | |
12052 | ||
12053 | ||
12054 | ||
12055 | <HR> | |
12056 | <TABLE WIDTH=100%> | |
12057 | <TR> | |
12058 | <TH ALIGN=LEFT width=33%>GNU Bash-4.0<TH ALIGN=CENTER width=33%>2008 December 29<TH ALIGN=RIGHT width=33%>BASH(1) | |
12059 | </TR> | |
12060 | </TABLE> | |
12061 | <HR> | |
12062 | <A NAME="index"> </A><H2>Index</H2> | |
12063 | <DL> | |
12064 | <DT><A HREF="#lbAB">NAME</A><DD> | |
12065 | <DT><A HREF="#lbAC">SYNOPSIS</A><DD> | |
12066 | <DT><A HREF="#lbAD">COPYRIGHT</A><DD> | |
12067 | <DT><A HREF="#lbAE">DESCRIPTION</A><DD> | |
12068 | <DT><A HREF="#lbAF">OPTIONS</A><DD> | |
12069 | <DT><A HREF="#lbAG">ARGUMENTS</A><DD> | |
12070 | <DT><A HREF="#lbAH">INVOCATION</A><DD> | |
12071 | <DT><A HREF="#lbAI">DEFINITIONS</A><DD> | |
12072 | <DT><A HREF="#lbAJ">RESERVED WORDS</A><DD> | |
12073 | <DT><A HREF="#lbAK">SHELL GRAMMAR</A><DD> | |
12074 | <DL> | |
12075 | <DT><A HREF="#lbAL">Simple Commands</A><DD> | |
12076 | <DT><A HREF="#lbAM">Pipelines</A><DD> | |
12077 | <DT><A HREF="#lbAN">Lists</A><DD> | |
12078 | <DT><A HREF="#lbAO">Compound Commands</A><DD> | |
12079 | <DT><A HREF="#lbAP">Coprocesses</A><DD> | |
12080 | <DT><A HREF="#lbAQ">Shell Function Definitions</A><DD> | |
12081 | </DL> | |
12082 | <DT><A HREF="#lbAR">COMMENTS</A><DD> | |
12083 | <DT><A HREF="#lbAS">QUOTING</A><DD> | |
12084 | <DT><A HREF="#lbAT">PARAMETERS</A><DD> | |
12085 | <DL> | |
12086 | <DT><A HREF="#lbAU">Positional Parameters</A><DD> | |
12087 | <DT><A HREF="#lbAV">Special Parameters</A><DD> | |
12088 | <DT><A HREF="#lbAW">Shell Variables</A><DD> | |
12089 | <DT><A HREF="#lbAX">Arrays</A><DD> | |
12090 | </DL> | |
12091 | <DT><A HREF="#lbAY">EXPANSION</A><DD> | |
12092 | <DL> | |
12093 | <DT><A HREF="#lbAZ">Brace Expansion</A><DD> | |
12094 | <DT><A HREF="#lbBA">Tilde Expansion</A><DD> | |
12095 | <DT><A HREF="#lbBB">Parameter Expansion</A><DD> | |
12096 | <DT><A HREF="#lbBC">Command Substitution</A><DD> | |
12097 | <DT><A HREF="#lbBD">Arithmetic Expansion</A><DD> | |
12098 | <DT><A HREF="#lbBE">Process Substitution</A><DD> | |
12099 | <DT><A HREF="#lbBF">Word Splitting</A><DD> | |
12100 | <DT><A HREF="#lbBG">Pathname Expansion</A><DD> | |
12101 | <DT><A HREF="#lbBH">Quote Removal</A><DD> | |
12102 | </DL> | |
12103 | <DT><A HREF="#lbBI">REDIRECTION</A><DD> | |
12104 | <DL> | |
12105 | <DT><A HREF="#lbBJ">Redirecting Input</A><DD> | |
12106 | <DT><A HREF="#lbBK">Redirecting Output</A><DD> | |
12107 | <DT><A HREF="#lbBL">Appending Redirected Output</A><DD> | |
12108 | <DT><A HREF="#lbBM">Redirecting Standard Output and Standard Error</A><DD> | |
12109 | <DT><A HREF="#lbBN">Appending Standard Output and Standard Error</A><DD> | |
12110 | <DT><A HREF="#lbBO">Here Documents</A><DD> | |
12111 | <DT><A HREF="#lbBP">Here Strings</A><DD> | |
12112 | <DT><A HREF="#lbBQ">Duplicating File Descriptors</A><DD> | |
12113 | <DT><A HREF="#lbBR">Moving File Descriptors</A><DD> | |
12114 | <DT><A HREF="#lbBS">Opening File Descriptors for Reading and Writing</A><DD> | |
12115 | </DL> | |
12116 | <DT><A HREF="#lbBT">ALIASES</A><DD> | |
12117 | <DT><A HREF="#lbBU">FUNCTIONS</A><DD> | |
12118 | <DT><A HREF="#lbBV">ARITHMETIC EVALUATION</A><DD> | |
12119 | <DT><A HREF="#lbBW">CONDITIONAL EXPRESSIONS</A><DD> | |
12120 | <DT><A HREF="#lbBX">SIMPLE COMMAND EXPANSION</A><DD> | |
12121 | <DT><A HREF="#lbBY">COMMAND EXECUTION</A><DD> | |
12122 | <DT><A HREF="#lbBZ">COMMAND EXECUTION ENVIRONMENT</A><DD> | |
12123 | <DT><A HREF="#lbCA">ENVIRONMENT</A><DD> | |
12124 | <DT><A HREF="#lbCB">EXIT STATUS</A><DD> | |
12125 | <DT><A HREF="#lbCC">SIGNALS</A><DD> | |
12126 | <DT><A HREF="#lbCD">JOB CONTROL</A><DD> | |
12127 | <DT><A HREF="#lbCE">PROMPTING</A><DD> | |
12128 | <DT><A HREF="#lbCF">READLINE</A><DD> | |
12129 | <DL> | |
12130 | <DT><A HREF="#lbCG">Readline Notation</A><DD> | |
12131 | <DT><A HREF="#lbCH">Readline Initialization</A><DD> | |
12132 | <DT><A HREF="#lbCI">Readline Key Bindings</A><DD> | |
12133 | <DT><A HREF="#lbCJ">Readline Variables</A><DD> | |
12134 | <DT><A HREF="#lbCK">Readline Conditional Constructs</A><DD> | |
12135 | <DT><A HREF="#lbCL">Searching</A><DD> | |
12136 | <DT><A HREF="#lbCM">Readline Command Names</A><DD> | |
12137 | <DT><A HREF="#lbCN">Commands for Moving</A><DD> | |
12138 | <DT><A HREF="#lbCO">Commands for Manipulating the History</A><DD> | |
12139 | <DT><A HREF="#lbCP">Commands for Changing Text</A><DD> | |
12140 | <DT><A HREF="#lbCQ">Killing and Yanking</A><DD> | |
12141 | <DT><A HREF="#lbCR">Numeric Arguments</A><DD> | |
12142 | <DT><A HREF="#lbCS">Completing</A><DD> | |
12143 | <DT><A HREF="#lbCT">Keyboard Macros</A><DD> | |
12144 | <DT><A HREF="#lbCU">Miscellaneous</A><DD> | |
12145 | <DT><A HREF="#lbCV">Programmable Completion</A><DD> | |
12146 | </DL> | |
12147 | <DT><A HREF="#lbCW">HISTORY</A><DD> | |
12148 | <DT><A HREF="#lbCX">HISTORY EXPANSION</A><DD> | |
12149 | <DL> | |
12150 | <DT><A HREF="#lbCY">Event Designators</A><DD> | |
12151 | <DT><A HREF="#lbCZ">Word Designators</A><DD> | |
12152 | <DT><A HREF="#lbDA">Modifiers</A><DD> | |
12153 | </DL> | |
12154 | <DT><A HREF="#lbDB">SHELL BUILTIN COMMANDS</A><DD> | |
12155 | <DT><A HREF="#lbDC">RESTRICTED SHELL</A><DD> | |
12156 | <DT><A HREF="#lbDD">SEE ALSO</A><DD> | |
12157 | <DT><A HREF="#lbDE">FILES</A><DD> | |
12158 | <DT><A HREF="#lbDF">AUTHORS</A><DD> | |
12159 | <DT><A HREF="#lbDG">BUG REPORTS</A><DD> | |
12160 | <DT><A HREF="#lbDH">BUGS</A><DD> | |
12161 | </DL> | |
12162 | <HR> | |
12163 | This document was created by man2html from bash.1.<BR> | |
12164 | Time: 05 February 2009 08:05:34 EST | |
12165 | </BODY> | |
12166 | </HTML> |