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6a8fd0ed | 1 | This is bashref.info, produced by makeinfo version 4.11 from |
ed35cb4a | 2 | /Users/chet/src/bash/src/doc/bashref.texi. |
e8ce775d | 3 | |
6a8fd0ed | 4 | This text is a brief description of the features that are present in |
ed35cb4a | 5 | the Bash shell (version 4.0, 25 May 2008). |
d3a24ed2 | 6 | |
ed35cb4a CR |
7 | This is Edition 4.0, last updated 25 May 2008, of `The GNU Bash |
8 | Reference Manual', for `Bash', Version 4.0. | |
d3a24ed2 | 9 | |
c2a47ea9 | 10 | Copyright (C) 1988-2007 Free Software Foundation, Inc. |
d3a24ed2 CR |
11 | |
12 | Permission is granted to make and distribute verbatim copies of this | |
13 | manual provided the copyright notice and this permission notice are | |
14 | preserved on all copies. | |
15 | ||
16 | Permission is granted to copy, distribute and/or modify this | |
17 | document under the terms of the GNU Free Documentation License, | |
d3ad40de | 18 | Version 1.2 or any later version published by the Free Software |
d3a24ed2 | 19 | Foundation; with no Invariant Sections, with the Front-Cover texts |
c2a47ea9 | 20 | being "A GNU Manual", and with the Back-Cover Texts as in (a) |
d3a24ed2 | 21 | below. A copy of the license is included in the section entitled |
c2a47ea9 | 22 | "GNU Free Documentation License". |
d3a24ed2 | 23 | |
29d25b54 CR |
24 | (a) The FSF's Back-Cover Text is: "You have the freedom to copy |
25 | and modify this GNU manual. Buying copies from the FSF supports | |
26 | it in developing GNU and promoting software freedom." | |
27 | ||
37c41ab1 | 28 | |
d3a24ed2 | 29 | INFO-DIR-SECTION Basics |
e8ce775d | 30 | START-INFO-DIR-ENTRY |
cce855bc | 31 | * Bash: (bash). The GNU Bourne-Again SHell. |
e8ce775d | 32 | END-INFO-DIR-ENTRY |
ccc6cda3 | 33 | |
ccc6cda3 JA |
34 | \1f |
35 | File: bashref.info, Node: Top, Next: Introduction, Prev: (dir), Up: (dir) | |
36 | ||
37 | Bash Features | |
38 | ************* | |
39 | ||
37c41ab1 | 40 | This text is a brief description of the features that are present in |
ed35cb4a | 41 | the Bash shell (version 4.0, 25 May 2008). |
ccc6cda3 | 42 | |
ed35cb4a CR |
43 | This is Edition 4.0, last updated 25 May 2008, of `The GNU Bash |
44 | Reference Manual', for `Bash', Version 4.0. | |
ccc6cda3 JA |
45 | |
46 | Bash contains features that appear in other popular shells, and some | |
47 | features that only appear in Bash. Some of the shells that Bash has | |
48 | borrowed concepts from are the Bourne Shell (`sh'), the Korn Shell | |
49 | (`ksh'), and the C-shell (`csh' and its successor, `tcsh'). The | |
50 | following menu breaks the features up into categories based upon which | |
51 | one of these other shells inspired the feature. | |
52 | ||
53 | This manual is meant as a brief introduction to features found in | |
54 | Bash. The Bash manual page should be used as the definitive reference | |
55 | on shell behavior. | |
56 | ||
57 | * Menu: | |
58 | ||
59 | * Introduction:: An introduction to the shell. | |
ccc6cda3 JA |
60 | * Definitions:: Some definitions used in the rest of this |
61 | manual. | |
ccc6cda3 | 62 | * Basic Shell Features:: The shell "building blocks". |
bb70624e | 63 | * Shell Builtin Commands:: Commands that are a part of the shell. |
bb70624e | 64 | * Shell Variables:: Variables used or set by Bash. |
ccc6cda3 | 65 | * Bash Features:: Features found only in Bash. |
1c72c0cd CR |
66 | * Job Control:: What job control is and how Bash allows you |
67 | to use it. | |
ccc6cda3 JA |
68 | * Command Line Editing:: Chapter describing the command line |
69 | editing features. | |
c2a47ea9 | 70 | * Using History Interactively:: Command History Expansion |
ccc6cda3 | 71 | * Installing Bash:: How to build and install Bash on your system. |
ccc6cda3 | 72 | * Reporting Bugs:: How to report bugs in Bash. |
bb70624e JA |
73 | * Major Differences From The Bourne Shell:: A terse list of the differences |
74 | between Bash and historical | |
75 | versions of /bin/sh. | |
c2a47ea9 | 76 | * GNU Free Documentation License:: Copying and sharing this documentation. |
d3ad40de | 77 | * Indexes:: Various indexes for this manual. |
ccc6cda3 JA |
78 | |
79 | \1f | |
80 | File: bashref.info, Node: Introduction, Next: Definitions, Prev: Top, Up: Top | |
81 | ||
37c41ab1 CR |
82 | 1 Introduction |
83 | ************** | |
ccc6cda3 JA |
84 | |
85 | * Menu: | |
86 | ||
87 | * What is Bash?:: A short description of Bash. | |
ccc6cda3 JA |
88 | * What is a shell?:: A brief introduction to shells. |
89 | ||
90 | \1f | |
91 | File: bashref.info, Node: What is Bash?, Next: What is a shell?, Up: Introduction | |
92 | ||
37c41ab1 CR |
93 | 1.1 What is Bash? |
94 | ================= | |
ccc6cda3 | 95 | |
37c41ab1 | 96 | Bash is the shell, or command language interpreter, for the GNU |
bb70624e JA |
97 | operating system. The name is an acronym for the `Bourne-Again SHell', |
98 | a pun on Stephen Bourne, the author of the direct ancestor of the | |
d3a24ed2 CR |
99 | current Unix shell `sh', which appeared in the Seventh Edition Bell |
100 | Labs Research version of Unix. | |
ccc6cda3 | 101 | |
bb70624e JA |
102 | Bash is largely compatible with `sh' and incorporates useful |
103 | features from the Korn shell `ksh' and the C shell `csh'. It is | |
104 | intended to be a conformant implementation of the IEEE POSIX Shell and | |
ac18b312 CR |
105 | Tools portion of the IEEE POSIX specification (IEEE Standard 1003.1). |
106 | It offers functional improvements over `sh' for both interactive and | |
107 | programming use. | |
ccc6cda3 | 108 | |
bb70624e JA |
109 | While the GNU operating system provides other shells, including a |
110 | version of `csh', Bash is the default shell. Like other GNU software, | |
111 | Bash is quite portable. It currently runs on nearly every version of | |
112 | Unix and a few other operating systems - independently-supported ports | |
d3a24ed2 | 113 | exist for MS-DOS, OS/2, and Windows platforms. |
ccc6cda3 JA |
114 | |
115 | \1f | |
116 | File: bashref.info, Node: What is a shell?, Prev: What is Bash?, Up: Introduction | |
117 | ||
37c41ab1 CR |
118 | 1.2 What is a shell? |
119 | ==================== | |
ccc6cda3 | 120 | |
37c41ab1 | 121 | At its base, a shell is simply a macro processor that executes |
d3a24ed2 CR |
122 | commands. The term macro processor means functionality where text and |
123 | symbols are expanded to create larger expressions. | |
124 | ||
125 | A Unix shell is both a command interpreter and a programming | |
126 | language. As a command interpreter, the shell provides the user | |
127 | interface to the rich set of GNU utilities. The programming language | |
d3ad40de | 128 | features allow these utilities to be combined. Files containing |
cce855bc | 129 | commands can be created, and become commands themselves. These new |
bb70624e | 130 | commands have the same status as system commands in directories such as |
d3a24ed2 CR |
131 | `/bin', allowing users or groups to establish custom environments to |
132 | automate their common tasks. | |
133 | ||
134 | Shells may be used interactively or non-interactively. In | |
135 | interactive mode, they accept input typed from the keyboard. When | |
136 | executing non-interactively, shells execute commands read from a file. | |
ccc6cda3 | 137 | |
bb70624e | 138 | A shell allows execution of GNU commands, both synchronously and |
cce855bc JA |
139 | asynchronously. The shell waits for synchronous commands to complete |
140 | before accepting more input; asynchronous commands continue to execute | |
141 | in parallel with the shell while it reads and executes additional | |
142 | commands. The "redirection" constructs permit fine-grained control of | |
bb70624e | 143 | the input and output of those commands. Moreover, the shell allows |
d3a24ed2 | 144 | control over the contents of commands' environments. |
bb70624e JA |
145 | |
146 | Shells also provide a small set of built-in commands ("builtins") | |
147 | implementing functionality impossible or inconvenient to obtain via | |
148 | separate utilities. For example, `cd', `break', `continue', and | |
149 | `exec') cannot be implemented outside of the shell because they | |
150 | directly manipulate the shell itself. The `history', `getopts', | |
151 | `kill', or `pwd' builtins, among others, could be implemented in | |
152 | separate utilities, but they are more convenient to use as builtin | |
153 | commands. All of the shell builtins are described in subsequent | |
154 | sections. | |
ccc6cda3 JA |
155 | |
156 | While executing commands is essential, most of the power (and | |
157 | complexity) of shells is due to their embedded programming languages. | |
158 | Like any high-level language, the shell provides variables, flow | |
159 | control constructs, quoting, and functions. | |
160 | ||
bb70624e JA |
161 | Shells offer features geared specifically for interactive use rather |
162 | than to augment the programming language. These interactive features | |
d3a24ed2 CR |
163 | include job control, command line editing, command history and aliases. |
164 | Each of these features is described in this manual. | |
ccc6cda3 JA |
165 | |
166 | \1f | |
167 | File: bashref.info, Node: Definitions, Next: Basic Shell Features, Prev: Introduction, Up: Top | |
168 | ||
37c41ab1 CR |
169 | 2 Definitions |
170 | ************* | |
ccc6cda3 | 171 | |
37c41ab1 | 172 | These definitions are used throughout the remainder of this manual. |
ccc6cda3 JA |
173 | |
174 | `POSIX' | |
175 | A family of open system standards based on Unix. Bash is | |
ac18b312 CR |
176 | primarily concerned with the Shell and Utilities portion of the |
177 | POSIX 1003.1 standard. | |
ccc6cda3 JA |
178 | |
179 | `blank' | |
180 | A space or tab character. | |
181 | ||
182 | `builtin' | |
183 | A command that is implemented internally by the shell itself, | |
184 | rather than by an executable program somewhere in the file system. | |
185 | ||
186 | `control operator' | |
3d4e09aa | 187 | A `token' that performs a control function. It is a `newline' or |
ed35cb4a CR |
188 | one of the following: `||', `&&', `&', `;', `;;', `|', `|&', `(', |
189 | or `)'. | |
ccc6cda3 JA |
190 | |
191 | `exit status' | |
f73dda09 JA |
192 | The value returned by a command to its caller. The value is |
193 | restricted to eight bits, so the maximum value is 255. | |
ccc6cda3 JA |
194 | |
195 | `field' | |
196 | A unit of text that is the result of one of the shell expansions. | |
197 | After expansion, when executing a command, the resulting fields | |
198 | are used as the command name and arguments. | |
199 | ||
200 | `filename' | |
201 | A string of characters used to identify a file. | |
202 | ||
203 | `job' | |
204 | A set of processes comprising a pipeline, and any processes | |
205 | descended from it, that are all in the same process group. | |
206 | ||
207 | `job control' | |
d166f048 JA |
208 | A mechanism by which users can selectively stop (suspend) and |
209 | restart (resume) execution of processes. | |
ccc6cda3 JA |
210 | |
211 | `metacharacter' | |
212 | A character that, when unquoted, separates words. A metacharacter | |
213 | is a `blank' or one of the following characters: `|', `&', `;', | |
214 | `(', `)', `<', or `>'. | |
215 | ||
216 | `name' | |
217 | A `word' consisting solely of letters, numbers, and underscores, | |
218 | and beginning with a letter or underscore. `Name's are used as | |
219 | shell variable and function names. Also referred to as an | |
220 | `identifier'. | |
221 | ||
222 | `operator' | |
223 | A `control operator' or a `redirection operator'. *Note | |
224 | Redirections::, for a list of redirection operators. | |
225 | ||
226 | `process group' | |
227 | A collection of related processes each having the same process | |
228 | group ID. | |
229 | ||
230 | `process group ID' | |
d3ad40de | 231 | A unique identifier that represents a `process group' during its |
ccc6cda3 JA |
232 | lifetime. |
233 | ||
234 | `reserved word' | |
235 | A `word' that has a special meaning to the shell. Most reserved | |
236 | words introduce shell flow control constructs, such as `for' and | |
237 | `while'. | |
238 | ||
239 | `return status' | |
240 | A synonym for `exit status'. | |
241 | ||
242 | `signal' | |
bb70624e | 243 | A mechanism by which a process may be notified by the kernel of an |
ccc6cda3 JA |
244 | event occurring in the system. |
245 | ||
246 | `special builtin' | |
247 | A shell builtin command that has been classified as special by the | |
ac18b312 | 248 | POSIX standard. |
ccc6cda3 JA |
249 | |
250 | `token' | |
251 | A sequence of characters considered a single unit by the shell. | |
252 | It is either a `word' or an `operator'. | |
253 | ||
254 | `word' | |
255 | A `token' that is not an `operator'. | |
256 | ||
257 | \1f | |
bb70624e | 258 | File: bashref.info, Node: Basic Shell Features, Next: Shell Builtin Commands, Prev: Definitions, Up: Top |
ccc6cda3 | 259 | |
37c41ab1 CR |
260 | 3 Basic Shell Features |
261 | ********************** | |
ccc6cda3 | 262 | |
37c41ab1 CR |
263 | Bash is an acronym for `Bourne-Again SHell'. The Bourne shell is the |
264 | traditional Unix shell originally written by Stephen Bourne. All of | |
265 | the Bourne shell builtin commands are available in Bash, The rules for | |
266 | evaluation and quoting are taken from the POSIX specification for the | |
267 | `standard' Unix shell. | |
ccc6cda3 | 268 | |
cce855bc | 269 | This chapter briefly summarizes the shell's `building blocks': |
ccc6cda3 JA |
270 | commands, control structures, shell functions, shell parameters, shell |
271 | expansions, redirections, which are a way to direct input and output | |
272 | from and to named files, and how the shell executes commands. | |
273 | ||
274 | * Menu: | |
275 | ||
276 | * Shell Syntax:: What your input means to the shell. | |
cce855bc | 277 | * Shell Commands:: The types of commands you can use. |
ccc6cda3 | 278 | * Shell Functions:: Grouping commands by name. |
d3a24ed2 CR |
279 | * Shell Parameters:: How the shell stores values. |
280 | * Shell Expansions:: How Bash expands parameters and the various | |
ccc6cda3 JA |
281 | expansions available. |
282 | * Redirections:: A way to control where input and output go. | |
283 | * Executing Commands:: What happens when you run a command. | |
284 | * Shell Scripts:: Executing files of shell commands. | |
285 | ||
286 | \1f | |
cce855bc | 287 | File: bashref.info, Node: Shell Syntax, Next: Shell Commands, Up: Basic Shell Features |
ccc6cda3 | 288 | |
37c41ab1 CR |
289 | 3.1 Shell Syntax |
290 | ================ | |
ccc6cda3 JA |
291 | |
292 | * Menu: | |
293 | ||
294 | * Shell Operation:: The basic operation of the shell. | |
ccc6cda3 | 295 | * Quoting:: How to remove the special meaning from characters. |
ccc6cda3 JA |
296 | * Comments:: How to specify comments. |
297 | ||
bb70624e JA |
298 | When the shell reads input, it proceeds through a sequence of |
299 | operations. If the input indicates the beginning of a comment, the | |
300 | shell ignores the comment symbol (`#'), and the rest of that line. | |
301 | ||
302 | Otherwise, roughly speaking, the shell reads its input and divides | |
303 | the input into words and operators, employing the quoting rules to | |
304 | select which meanings to assign various words and characters. | |
305 | ||
306 | The shell then parses these tokens into commands and other | |
307 | constructs, removes the special meaning of certain words or characters, | |
308 | expands others, redirects input and output as needed, executes the | |
309 | specified command, waits for the command's exit status, and makes that | |
310 | exit status available for further inspection or processing. | |
311 | ||
ccc6cda3 JA |
312 | \1f |
313 | File: bashref.info, Node: Shell Operation, Next: Quoting, Up: Shell Syntax | |
314 | ||
37c41ab1 CR |
315 | 3.1.1 Shell Operation |
316 | --------------------- | |
ccc6cda3 | 317 | |
37c41ab1 | 318 | The following is a brief description of the shell's operation when it |
ccc6cda3 JA |
319 | reads and executes a command. Basically, the shell does the following: |
320 | ||
28ef6c31 | 321 | 1. Reads its input from a file (*note Shell Scripts::), from a string |
ccc6cda3 | 322 | supplied as an argument to the `-c' invocation option (*note |
28ef6c31 | 323 | Invoking Bash::), or from the user's terminal. |
ccc6cda3 JA |
324 | |
325 | 2. Breaks the input into words and operators, obeying the quoting | |
6a8fd0ed | 326 | rules described in *note Quoting::. These tokens are separated by |
ccc6cda3 | 327 | `metacharacters'. Alias expansion is performed by this step |
28ef6c31 | 328 | (*note Aliases::). |
ccc6cda3 | 329 | |
cce855bc | 330 | 3. Parses the tokens into simple and compound commands (*note Shell |
28ef6c31 | 331 | Commands::). |
ccc6cda3 | 332 | |
28ef6c31 | 333 | 4. Performs the various shell expansions (*note Shell Expansions::), |
ccc6cda3 | 334 | breaking the expanded tokens into lists of filenames (*note |
28ef6c31 | 335 | Filename Expansion::) and commands and arguments. |
ccc6cda3 | 336 | |
28ef6c31 | 337 | 5. Performs any necessary redirections (*note Redirections::) and |
ccc6cda3 JA |
338 | removes the redirection operators and their operands from the |
339 | argument list. | |
340 | ||
28ef6c31 | 341 | 6. Executes the command (*note Executing Commands::). |
ccc6cda3 JA |
342 | |
343 | 7. Optionally waits for the command to complete and collects its exit | |
28ef6c31 | 344 | status (*note Exit Status::). |
ccc6cda3 JA |
345 | |
346 | ||
347 | \1f | |
348 | File: bashref.info, Node: Quoting, Next: Comments, Prev: Shell Operation, Up: Shell Syntax | |
349 | ||
37c41ab1 CR |
350 | 3.1.2 Quoting |
351 | ------------- | |
ccc6cda3 JA |
352 | |
353 | * Menu: | |
354 | ||
355 | * Escape Character:: How to remove the special meaning from a single | |
356 | character. | |
357 | * Single Quotes:: How to inhibit all interpretation of a sequence | |
358 | of characters. | |
359 | * Double Quotes:: How to suppress most of the interpretation of a | |
360 | sequence of characters. | |
361 | * ANSI-C Quoting:: How to expand ANSI-C sequences in quoted strings. | |
ccc6cda3 JA |
362 | * Locale Translation:: How to translate strings into different languages. |
363 | ||
364 | Quoting is used to remove the special meaning of certain characters | |
365 | or words to the shell. Quoting can be used to disable special | |
366 | treatment for special characters, to prevent reserved words from being | |
367 | recognized as such, and to prevent parameter expansion. | |
368 | ||
28ef6c31 | 369 | Each of the shell metacharacters (*note Definitions::) has special |
cce855bc | 370 | meaning to the shell and must be quoted if it is to represent itself. |
01ed5ba4 CR |
371 | When the command history expansion facilities are being used (*note |
372 | History Interaction::), the HISTORY EXPANSION character, usually `!', | |
373 | must be quoted to prevent history expansion. *Note Bash History | |
374 | Facilities::, for more details concerning history expansion. | |
d3a24ed2 CR |
375 | |
376 | There are three quoting mechanisms: the ESCAPE CHARACTER, single | |
377 | quotes, and double quotes. | |
ccc6cda3 JA |
378 | |
379 | \1f | |
380 | File: bashref.info, Node: Escape Character, Next: Single Quotes, Up: Quoting | |
381 | ||
37c41ab1 CR |
382 | 3.1.2.1 Escape Character |
383 | ........................ | |
ccc6cda3 | 384 | |
37c41ab1 CR |
385 | A non-quoted backslash `\' is the Bash escape character. It preserves |
386 | the literal value of the next character that follows, with the | |
387 | exception of `newline'. If a `\newline' pair appears, and the | |
cce855bc JA |
388 | backslash itself is not quoted, the `\newline' is treated as a line |
389 | continuation (that is, it is removed from the input stream and | |
390 | effectively ignored). | |
ccc6cda3 JA |
391 | |
392 | \1f | |
393 | File: bashref.info, Node: Single Quotes, Next: Double Quotes, Prev: Escape Character, Up: Quoting | |
394 | ||
37c41ab1 CR |
395 | 3.1.2.2 Single Quotes |
396 | ..................... | |
ccc6cda3 | 397 | |
37c41ab1 CR |
398 | Enclosing characters in single quotes (`'') preserves the literal value |
399 | of each character within the quotes. A single quote may not occur | |
bb70624e | 400 | between single quotes, even when preceded by a backslash. |
ccc6cda3 JA |
401 | |
402 | \1f | |
403 | File: bashref.info, Node: Double Quotes, Next: ANSI-C Quoting, Prev: Single Quotes, Up: Quoting | |
404 | ||
37c41ab1 CR |
405 | 3.1.2.3 Double Quotes |
406 | ..................... | |
ccc6cda3 | 407 | |
37c41ab1 CR |
408 | Enclosing characters in double quotes (`"') preserves the literal value |
409 | of all characters within the quotes, with the exception of `$', ``', | |
01ed5ba4 CR |
410 | `\', and, when history expansion is enabled, `!'. The characters `$' |
411 | and ``' retain their special meaning within double quotes (*note Shell | |
412 | Expansions::). The backslash retains its special meaning only when | |
413 | followed by one of the following characters: `$', ``', `"', `\', or | |
414 | `newline'. Within double quotes, backslashes that are followed by one | |
415 | of these characters are removed. Backslashes preceding characters | |
416 | without a special meaning are left unmodified. A double quote may be | |
417 | quoted within double quotes by preceding it with a backslash. If | |
418 | enabled, history expansion will be performed unless an `!' appearing in | |
419 | double quotes is escaped using a backslash. The backslash preceding | |
420 | the `!' is not removed. | |
ccc6cda3 JA |
421 | |
422 | The special parameters `*' and `@' have special meaning when in | |
28ef6c31 | 423 | double quotes (*note Shell Parameter Expansion::). |
ccc6cda3 JA |
424 | |
425 | \1f | |
426 | File: bashref.info, Node: ANSI-C Quoting, Next: Locale Translation, Prev: Double Quotes, Up: Quoting | |
427 | ||
37c41ab1 CR |
428 | 3.1.2.4 ANSI-C Quoting |
429 | ...................... | |
ccc6cda3 | 430 | |
37c41ab1 CR |
431 | Words of the form `$'STRING'' are treated specially. The word expands |
432 | to STRING, with backslash-escaped characters replaced as specified by | |
433 | the ANSI C standard. Backslash escape sequences, if present, are | |
434 | decoded as follows: | |
ccc6cda3 JA |
435 | |
436 | `\a' | |
437 | alert (bell) | |
438 | ||
439 | `\b' | |
440 | backspace | |
441 | ||
442 | `\e' | |
443 | an escape character (not ANSI C) | |
444 | ||
445 | `\f' | |
446 | form feed | |
447 | ||
448 | `\n' | |
449 | newline | |
450 | ||
451 | `\r' | |
452 | carriage return | |
453 | ||
454 | `\t' | |
455 | horizontal tab | |
456 | ||
457 | `\v' | |
458 | vertical tab | |
459 | ||
460 | `\\' | |
461 | backslash | |
462 | ||
bb70624e JA |
463 | `\'' |
464 | single quote | |
465 | ||
ccc6cda3 | 466 | `\NNN' |
f73dda09 | 467 | the eight-bit character whose value is the octal value NNN (one to |
cce855bc JA |
468 | three digits) |
469 | ||
f73dda09 JA |
470 | `\xHH' |
471 | the eight-bit character whose value is the hexadecimal value HH | |
472 | (one or two hex digits) | |
ccc6cda3 | 473 | |
7117c2d2 JA |
474 | `\cX' |
475 | a control-X character | |
476 | ||
bb70624e JA |
477 | The expanded result is single-quoted, as if the dollar sign had not |
478 | been present. | |
ccc6cda3 JA |
479 | |
480 | \1f | |
481 | File: bashref.info, Node: Locale Translation, Prev: ANSI-C Quoting, Up: Quoting | |
482 | ||
37c41ab1 CR |
483 | 3.1.2.5 Locale-Specific Translation |
484 | ................................... | |
ccc6cda3 | 485 | |
37c41ab1 CR |
486 | A double-quoted string preceded by a dollar sign (`$') will cause the |
487 | string to be translated according to the current locale. If the | |
ccc6cda3 JA |
488 | current locale is `C' or `POSIX', the dollar sign is ignored. If the |
489 | string is translated and replaced, the replacement is double-quoted. | |
490 | ||
28ef6c31 JA |
491 | Some systems use the message catalog selected by the `LC_MESSAGES' |
492 | shell variable. Others create the name of the message catalog from the | |
493 | value of the `TEXTDOMAIN' shell variable, possibly adding a suffix of | |
494 | `.mo'. If you use the `TEXTDOMAIN' variable, you may need to set the | |
495 | `TEXTDOMAINDIR' variable to the location of the message catalog files. | |
f73dda09 JA |
496 | Still others use both variables in this fashion: |
497 | `TEXTDOMAINDIR'/`LC_MESSAGES'/LC_MESSAGES/`TEXTDOMAIN'.mo. | |
28ef6c31 | 498 | |
ccc6cda3 JA |
499 | \1f |
500 | File: bashref.info, Node: Comments, Prev: Quoting, Up: Shell Syntax | |
501 | ||
37c41ab1 CR |
502 | 3.1.3 Comments |
503 | -------------- | |
ccc6cda3 | 504 | |
37c41ab1 | 505 | In a non-interactive shell, or an interactive shell in which the |
ccc6cda3 | 506 | `interactive_comments' option to the `shopt' builtin is enabled (*note |
d3ad40de CR |
507 | The Shopt Builtin::), a word beginning with `#' causes that word and |
508 | all remaining characters on that line to be ignored. An interactive | |
509 | shell without the `interactive_comments' option enabled does not allow | |
ccc6cda3 | 510 | comments. The `interactive_comments' option is on by default in |
bb70624e JA |
511 | interactive shells. *Note Interactive Shells::, for a description of |
512 | what makes a shell interactive. | |
cce855bc JA |
513 | |
514 | \1f | |
515 | File: bashref.info, Node: Shell Commands, Next: Shell Functions, Prev: Shell Syntax, Up: Basic Shell Features | |
516 | ||
37c41ab1 CR |
517 | 3.2 Shell Commands |
518 | ================== | |
cce855bc | 519 | |
37c41ab1 | 520 | A simple shell command such as `echo a b c' consists of the command |
bb70624e JA |
521 | itself followed by arguments, separated by spaces. |
522 | ||
523 | More complex shell commands are composed of simple commands arranged | |
524 | together in a variety of ways: in a pipeline in which the output of one | |
525 | command becomes the input of a second, in a loop or conditional | |
526 | construct, or in some other grouping. | |
527 | ||
cce855bc JA |
528 | * Menu: |
529 | ||
530 | * Simple Commands:: The most common type of command. | |
531 | * Pipelines:: Connecting the input and output of several | |
532 | commands. | |
533 | * Lists:: How to execute commands sequentially. | |
d3a24ed2 | 534 | * Compound Commands:: Shell commands for control flow. |
ccc6cda3 JA |
535 | |
536 | \1f | |
cce855bc | 537 | File: bashref.info, Node: Simple Commands, Next: Pipelines, Up: Shell Commands |
ccc6cda3 | 538 | |
37c41ab1 CR |
539 | 3.2.1 Simple Commands |
540 | --------------------- | |
ccc6cda3 | 541 | |
37c41ab1 CR |
542 | A simple command is the kind of command encountered most often. It's |
543 | just a sequence of words separated by `blank's, terminated by one of | |
544 | the shell's control operators (*note Definitions::). The first word | |
28ef6c31 | 545 | generally specifies a command to be executed, with the rest of the |
bb70624e | 546 | words being that command's arguments. |
ccc6cda3 | 547 | |
28ef6c31 | 548 | The return status (*note Exit Status::) of a simple command is its |
bb70624e JA |
549 | exit status as provided by the POSIX 1003.1 `waitpid' function, or |
550 | 128+N if the command was terminated by signal N. | |
ccc6cda3 JA |
551 | |
552 | \1f | |
cce855bc | 553 | File: bashref.info, Node: Pipelines, Next: Lists, Prev: Simple Commands, Up: Shell Commands |
ccc6cda3 | 554 | |
37c41ab1 CR |
555 | 3.2.2 Pipelines |
556 | --------------- | |
ccc6cda3 | 557 | |
ed35cb4a CR |
558 | A `pipeline' is a sequence of simple commands separated by one of the |
559 | control operators `|' or `|&'. | |
ccc6cda3 JA |
560 | |
561 | The format for a pipeline is | |
ed35cb4a | 562 | [`time' [`-p']] [`!'] COMMAND1 [ [`|' or `|&'] COMMAND2 ...] |
ccc6cda3 | 563 | |
f73dda09 JA |
564 | The output of each command in the pipeline is connected via a pipe to |
565 | the input of the next command. That is, each command reads the | |
ed35cb4a CR |
566 | previous command's output. This connection is performed before any |
567 | redirections specified by the command. | |
568 | ||
569 | If `|&' is used, the standard error of COMMAND1 is connected to | |
570 | COMMAND2's standard input through the pipe; it is shorthand for `2>&1 | |
571 | |'. This implicit redirection of the standard error is performed after | |
572 | any redirections specified by the command. | |
ccc6cda3 JA |
573 | |
574 | The reserved word `time' causes timing statistics to be printed for | |
cce855bc JA |
575 | the pipeline once it finishes. The statistics currently consist of |
576 | elapsed (wall-clock) time and user and system time consumed by the | |
577 | command's execution. The `-p' option changes the output format to that | |
578 | specified by POSIX. The `TIMEFORMAT' variable may be set to a format | |
579 | string that specifies how the timing information should be displayed. | |
580 | *Note Bash Variables::, for a description of the available formats. | |
581 | The use of `time' as a reserved word permits the timing of shell | |
582 | builtins, shell functions, and pipelines. An external `time' command | |
583 | cannot time these easily. | |
584 | ||
28ef6c31 | 585 | If the pipeline is not executed asynchronously (*note Lists::), the |
cce855bc | 586 | shell waits for all commands in the pipeline to complete. |
ccc6cda3 | 587 | |
cce855bc | 588 | Each command in a pipeline is executed in its own subshell (*note |
28ef6c31 | 589 | Command Execution Environment::). The exit status of a pipeline is the |
5e13499c CR |
590 | exit status of the last command in the pipeline, unless the `pipefail' |
591 | option is enabled (*note The Set Builtin::). If `pipefail' is enabled, | |
592 | the pipeline's return status is the value of the last (rightmost) | |
593 | command to exit with a non-zero status, or zero if all commands exit | |
594 | successfully. If the reserved word `!' precedes the pipeline, the exit | |
595 | status is the logical negation of the exit status as described above. | |
596 | The shell waits for all commands in the pipeline to terminate before | |
597 | returning a value. | |
ccc6cda3 JA |
598 | |
599 | \1f | |
d3a24ed2 | 600 | File: bashref.info, Node: Lists, Next: Compound Commands, Prev: Pipelines, Up: Shell Commands |
ccc6cda3 | 601 | |
37c41ab1 CR |
602 | 3.2.3 Lists of Commands |
603 | ----------------------- | |
ccc6cda3 | 604 | |
37c41ab1 CR |
605 | A `list' is a sequence of one or more pipelines separated by one of the |
606 | operators `;', `&', `&&', or `||', and optionally terminated by one of | |
607 | `;', `&', or a `newline'. | |
ccc6cda3 JA |
608 | |
609 | Of these list operators, `&&' and `||' have equal precedence, | |
610 | followed by `;' and `&', which have equal precedence. | |
611 | ||
7117c2d2 JA |
612 | A sequence of one or more newlines may appear in a `list' to delimit |
613 | commands, equivalent to a semicolon. | |
614 | ||
ccc6cda3 | 615 | If a command is terminated by the control operator `&', the shell |
cce855bc JA |
616 | executes the command asynchronously in a subshell. This is known as |
617 | executing the command in the BACKGROUND. The shell does not wait for | |
bb70624e | 618 | the command to finish, and the return status is 0 (true). When job |
28ef6c31 | 619 | control is not active (*note Job Control::), the standard input for |
bb70624e JA |
620 | asynchronous commands, in the absence of any explicit redirections, is |
621 | redirected from `/dev/null'. | |
cce855bc JA |
622 | |
623 | Commands separated by a `;' are executed sequentially; the shell | |
624 | waits for each command to terminate in turn. The return status is the | |
625 | exit status of the last command executed. | |
ccc6cda3 | 626 | |
6a8fd0ed CR |
627 | AND and OR lists are sequences of one or more pipelines separated by |
628 | the control operators `&&' and `||', respectively. AND and OR lists | |
629 | are executed with left associativity. | |
630 | ||
631 | An AND list has the form | |
bb70624e | 632 | COMMAND1 && COMMAND2 |
ccc6cda3 | 633 | |
bb70624e JA |
634 | COMMAND2 is executed if, and only if, COMMAND1 returns an exit status |
635 | of zero. | |
ccc6cda3 JA |
636 | |
637 | An OR list has the form | |
bb70624e | 638 | COMMAND1 || COMMAND2 |
ccc6cda3 | 639 | |
bb70624e | 640 | COMMAND2 is executed if, and only if, COMMAND1 returns a non-zero exit |
ccc6cda3 JA |
641 | status. |
642 | ||
643 | The return status of AND and OR lists is the exit status of the last | |
644 | command executed in the list. | |
645 | ||
646 | \1f | |
d3a24ed2 CR |
647 | File: bashref.info, Node: Compound Commands, Prev: Lists, Up: Shell Commands |
648 | ||
37c41ab1 CR |
649 | 3.2.4 Compound Commands |
650 | ----------------------- | |
d3a24ed2 CR |
651 | |
652 | * Menu: | |
653 | ||
654 | * Looping Constructs:: Shell commands for iterative action. | |
655 | * Conditional Constructs:: Shell commands for conditional execution. | |
656 | * Command Grouping:: Ways to group commands. | |
657 | ||
658 | Compound commands are the shell programming constructs. Each | |
659 | construct begins with a reserved word or control operator and is | |
660 | terminated by a corresponding reserved word or operator. Any | |
661 | redirections (*note Redirections::) associated with a compound command | |
662 | apply to all commands within that compound command unless explicitly | |
663 | overridden. | |
664 | ||
665 | Bash provides looping constructs, conditional commands, and | |
666 | mechanisms to group commands and execute them as a unit. | |
667 | ||
668 | \1f | |
669 | File: bashref.info, Node: Looping Constructs, Next: Conditional Constructs, Up: Compound Commands | |
ccc6cda3 | 670 | |
37c41ab1 CR |
671 | 3.2.4.1 Looping Constructs |
672 | .......................... | |
ccc6cda3 | 673 | |
37c41ab1 | 674 | Bash supports the following looping constructs. |
ccc6cda3 | 675 | |
bb70624e | 676 | Note that wherever a `;' appears in the description of a command's |
cce855bc JA |
677 | syntax, it may be replaced with one or more newlines. |
678 | ||
ccc6cda3 JA |
679 | `until' |
680 | The syntax of the `until' command is: | |
681 | until TEST-COMMANDS; do CONSEQUENT-COMMANDS; done | |
cce855bc JA |
682 | Execute CONSEQUENT-COMMANDS as long as TEST-COMMANDS has an exit |
683 | status which is not zero. The return status is the exit status of | |
684 | the last command executed in CONSEQUENT-COMMANDS, or zero if none | |
685 | was executed. | |
ccc6cda3 JA |
686 | |
687 | `while' | |
688 | The syntax of the `while' command is: | |
689 | while TEST-COMMANDS; do CONSEQUENT-COMMANDS; done | |
690 | ||
cce855bc JA |
691 | Execute CONSEQUENT-COMMANDS as long as TEST-COMMANDS has an exit |
692 | status of zero. The return status is the exit status of the last | |
693 | command executed in CONSEQUENT-COMMANDS, or zero if none was | |
694 | executed. | |
ccc6cda3 JA |
695 | |
696 | `for' | |
697 | The syntax of the `for' command is: | |
698 | ||
699 | for NAME [in WORDS ...]; do COMMANDS; done | |
cce855bc JA |
700 | Expand WORDS, and execute COMMANDS once for each member in the |
701 | resultant list, with NAME bound to the current member. If `in | |
bb70624e JA |
702 | WORDS' is not present, the `for' command executes the COMMANDS |
703 | once for each positional parameter that is set, as if `in "$@"' | |
28ef6c31 | 704 | had been specified (*note Special Parameters::). The return |
bb70624e JA |
705 | status is the exit status of the last command that executes. If |
706 | there are no items in the expansion of WORDS, no commands are | |
707 | executed, and the return status is zero. | |
708 | ||
709 | An alternate form of the `for' command is also supported: | |
710 | ||
711 | for (( EXPR1 ; EXPR2 ; EXPR3 )) ; do COMMANDS ; done | |
712 | First, the arithmetic expression EXPR1 is evaluated according to | |
28ef6c31 | 713 | the rules described below (*note Shell Arithmetic::). The |
bb70624e JA |
714 | arithmetic expression EXPR2 is then evaluated repeatedly until it |
715 | evaluates to zero. Each time EXPR2 evaluates to a non-zero value, | |
716 | COMMANDS are executed and the arithmetic expression EXPR3 is | |
717 | evaluated. If any expression is omitted, it behaves as if it | |
718 | evaluates to 1. The return value is the exit status of the last | |
719 | command in LIST that is executed, or false if any of the | |
720 | expressions is invalid. | |
ccc6cda3 | 721 | |
761783bf | 722 | |
28ef6c31 | 723 | The `break' and `continue' builtins (*note Bourne Shell Builtins::) |
ccc6cda3 JA |
724 | may be used to control loop execution. |
725 | ||
726 | \1f | |
d3a24ed2 | 727 | File: bashref.info, Node: Conditional Constructs, Next: Command Grouping, Prev: Looping Constructs, Up: Compound Commands |
ccc6cda3 | 728 | |
37c41ab1 CR |
729 | 3.2.4.2 Conditional Constructs |
730 | .............................. | |
ccc6cda3 JA |
731 | |
732 | `if' | |
733 | The syntax of the `if' command is: | |
734 | ||
735 | if TEST-COMMANDS; then | |
736 | CONSEQUENT-COMMANDS; | |
737 | [elif MORE-TEST-COMMANDS; then | |
738 | MORE-CONSEQUENTS;] | |
739 | [else ALTERNATE-CONSEQUENTS;] | |
740 | fi | |
741 | ||
cce855bc JA |
742 | The TEST-COMMANDS list is executed, and if its return status is |
743 | zero, the CONSEQUENT-COMMANDS list is executed. If TEST-COMMANDS | |
744 | returns a non-zero status, each `elif' list is executed in turn, | |
745 | and if its exit status is zero, the corresponding MORE-CONSEQUENTS | |
746 | is executed and the command completes. If `else | |
747 | ALTERNATE-CONSEQUENTS' is present, and the final command in the | |
748 | final `if' or `elif' clause has a non-zero exit status, then | |
749 | ALTERNATE-CONSEQUENTS is executed. The return status is the exit | |
750 | status of the last command executed, or zero if no condition | |
751 | tested true. | |
ccc6cda3 JA |
752 | |
753 | `case' | |
754 | The syntax of the `case' command is: | |
755 | ||
cce855bc | 756 | `case WORD in [ [(] PATTERN [| PATTERN]...) COMMAND-LIST ;;]... esac' |
ccc6cda3 | 757 | |
cce855bc | 758 | `case' will selectively execute the COMMAND-LIST corresponding to |
9d2b70f0 | 759 | the first PATTERN that matches WORD. If the shell option |
6a8fd0ed | 760 | `nocasematch' (see the description of `shopt' in *note The Shopt |
d3ad40de | 761 | Builtin::) is enabled, the match is performed without regard to |
9d2b70f0 | 762 | the case of alphabetic characters. The `|' is used to separate |
cce855bc JA |
763 | multiple patterns, and the `)' operator terminates a pattern list. |
764 | A list of patterns and an associated command-list is known as a | |
ed35cb4a CR |
765 | CLAUSE. |
766 | ||
767 | Each clause must be terminated with `;;', `,&', or `;;&'. The | |
768 | WORD undergoes tilde expansion, parameter expansion, command | |
cce855bc JA |
769 | substitution, arithmetic expansion, and quote removal before |
770 | matching is attempted. Each PATTERN undergoes tilde expansion, | |
771 | parameter expansion, command substitution, and arithmetic | |
772 | expansion. | |
773 | ||
774 | There may be an arbitrary number of `case' clauses, each terminated | |
ed35cb4a CR |
775 | by a `;;', `;&', or `;;&'. The first pattern that matches |
776 | determines the command-list that is executed. | |
ccc6cda3 JA |
777 | |
778 | Here is an example using `case' in a script that could be used to | |
779 | describe one interesting feature of an animal: | |
780 | ||
781 | echo -n "Enter the name of an animal: " | |
782 | read ANIMAL | |
783 | echo -n "The $ANIMAL has " | |
784 | case $ANIMAL in | |
785 | horse | dog | cat) echo -n "four";; | |
786 | man | kangaroo ) echo -n "two";; | |
787 | *) echo -n "an unknown number of";; | |
788 | esac | |
789 | echo " legs." | |
790 | ||
ed35cb4a CR |
791 | If the `;;' operator is used, no subsequent matches are attempted |
792 | after the first pattern match. Using `;&' in place of `;;' | |
793 | causes execution to continue with the COMMAND-LIST associated with | |
794 | the next clause, if any. Using `;;&' in place of `;;' causes the | |
795 | shell to test the patterns in the next clause, if any, and execute | |
796 | any associated COMMAND-LIST on a successful match. | |
797 | ||
cce855bc JA |
798 | The return status is zero if no PATTERN is matched. Otherwise, the |
799 | return status is the exit status of the COMMAND-LIST executed. | |
800 | ||
801 | `select' | |
802 | The `select' construct allows the easy generation of menus. It | |
803 | has almost the same syntax as the `for' command: | |
804 | ||
805 | select NAME [in WORDS ...]; do COMMANDS; done | |
806 | ||
807 | The list of words following `in' is expanded, generating a list of | |
808 | items. The set of expanded words is printed on the standard error | |
809 | output stream, each preceded by a number. If the `in WORDS' is | |
810 | omitted, the positional parameters are printed, as if `in "$@"' | |
d3ad40de | 811 | had been specified. The `PS3' prompt is then displayed and a line |
cce855bc JA |
812 | is read from the standard input. If the line consists of a number |
813 | corresponding to one of the displayed words, then the value of | |
814 | NAME is set to that word. If the line is empty, the words and | |
815 | prompt are displayed again. If `EOF' is read, the `select' | |
816 | command completes. Any other value read causes NAME to be set to | |
817 | null. The line read is saved in the variable `REPLY'. | |
818 | ||
f73dda09 JA |
819 | The COMMANDS are executed after each selection until a `break' |
820 | command is executed, at which point the `select' command completes. | |
cce855bc JA |
821 | |
822 | Here is an example that allows the user to pick a filename from the | |
823 | current directory, and displays the name and index of the file | |
824 | selected. | |
825 | ||
826 | select fname in *; | |
827 | do | |
828 | echo you picked $fname \($REPLY\) | |
829 | break; | |
830 | done | |
831 | ||
ccc6cda3 JA |
832 | `((...))' |
833 | (( EXPRESSION )) | |
834 | ||
cce855bc | 835 | The arithmetic EXPRESSION is evaluated according to the rules |
28ef6c31 | 836 | described below (*note Shell Arithmetic::). If the value of the |
cce855bc JA |
837 | expression is non-zero, the return status is 0; otherwise the |
838 | return status is 1. This is exactly equivalent to | |
ccc6cda3 | 839 | let "EXPRESSION" |
cce855bc JA |
840 | *Note Bash Builtins::, for a full description of the `let' builtin. |
841 | ||
842 | `[[...]]' | |
843 | [[ EXPRESSION ]] | |
844 | ||
845 | Return a status of 0 or 1 depending on the evaluation of the | |
846 | conditional expression EXPRESSION. Expressions are composed of | |
6a8fd0ed | 847 | the primaries described below in *note Bash Conditional |
cce855bc JA |
848 | Expressions::. Word splitting and filename expansion are not |
849 | performed on the words between the `[[' and `]]'; tilde expansion, | |
850 | parameter and variable expansion, arithmetic expansion, command | |
851 | substitution, process substitution, and quote removal are | |
d3a24ed2 CR |
852 | performed. Conditional operators such as `-f' must be unquoted to |
853 | be recognized as primaries. | |
cce855bc JA |
854 | |
855 | When the `==' and `!=' operators are used, the string to the right | |
856 | of the operator is considered a pattern and matched according to | |
6a8fd0ed | 857 | the rules described below in *note Pattern Matching::. If the |
9d2b70f0 | 858 | shell option `nocasematch' (see the description of `shopt' in |
6a8fd0ed | 859 | *note The Shopt Builtin::) is enabled, the match is performed |
d3ad40de CR |
860 | without regard to the case of alphabetic characters. The return |
861 | value is 0 if the string matches (`==') or does not match | |
862 | (`!=')the pattern, and 1 otherwise. Any part of the pattern may | |
863 | be quoted to force it to be matched as a string. | |
cce855bc | 864 | |
5e13499c CR |
865 | An additional binary operator, `=~', is available, with the same |
866 | precedence as `==' and `!='. When it is used, the string to the | |
867 | right of the operator is considered an extended regular expression | |
868 | and matched accordingly (as in regex3)). The return value is 0 if | |
869 | the string matches the pattern, and 1 otherwise. If the regular | |
870 | expression is syntactically incorrect, the conditional | |
9d2b70f0 | 871 | expression's return value is 2. If the shell option `nocasematch' |
6a8fd0ed | 872 | (see the description of `shopt' in *note The Shopt Builtin::) is |
5e13499c | 873 | enabled, the match is performed without regard to the case of |
3d4e09aa CR |
874 | alphabetic characters. Any part of the pattern may be quoted to |
875 | force it to be matched as a string. Substrings matched by | |
876 | parenthesized subexpressions within the regular expression are | |
877 | saved in the array variable `BASH_REMATCH'. The element of | |
878 | `BASH_REMATCH' with index 0 is the portion of the string matching | |
879 | the entire regular expression. The element of `BASH_REMATCH' with | |
880 | index N is the portion of the string matching the Nth | |
881 | parenthesized subexpression. | |
5e13499c | 882 | |
cce855bc JA |
883 | Expressions may be combined using the following operators, listed |
884 | in decreasing order of precedence: | |
885 | ||
886 | `( EXPRESSION )' | |
887 | Returns the value of EXPRESSION. This may be used to | |
888 | override the normal precedence of operators. | |
889 | ||
890 | `! EXPRESSION' | |
891 | True if EXPRESSION is false. | |
892 | ||
893 | `EXPRESSION1 && EXPRESSION2' | |
894 | True if both EXPRESSION1 and EXPRESSION2 are true. | |
895 | ||
896 | `EXPRESSION1 || EXPRESSION2' | |
897 | True if either EXPRESSION1 or EXPRESSION2 is true. | |
7117c2d2 JA |
898 | The `&&' and `||' operators do not evaluate EXPRESSION2 if the |
899 | value of EXPRESSION1 is sufficient to determine the return value | |
900 | of the entire conditional expression. | |
ccc6cda3 | 901 | |
761783bf | 902 | |
ccc6cda3 | 903 | \1f |
d3a24ed2 | 904 | File: bashref.info, Node: Command Grouping, Prev: Conditional Constructs, Up: Compound Commands |
ccc6cda3 | 905 | |
37c41ab1 CR |
906 | 3.2.4.3 Grouping Commands |
907 | ......................... | |
ccc6cda3 | 908 | |
37c41ab1 CR |
909 | Bash provides two ways to group a list of commands to be executed as a |
910 | unit. When commands are grouped, redirections may be applied to the | |
ccc6cda3 JA |
911 | entire command list. For example, the output of all the commands in |
912 | the list may be redirected to a single stream. | |
913 | ||
914 | `()' | |
915 | ( LIST ) | |
916 | ||
917 | Placing a list of commands between parentheses causes a subshell | |
d3a24ed2 CR |
918 | environment to be created (*note Command Execution Environment::), |
919 | and each of the commands in LIST to be executed in that subshell. | |
920 | Since the LIST is executed in a subshell, variable assignments do | |
921 | not remain in effect after the subshell completes. | |
ccc6cda3 JA |
922 | |
923 | `{}' | |
924 | { LIST; } | |
925 | ||
926 | Placing a list of commands between curly braces causes the list to | |
927 | be executed in the current shell context. No subshell is created. | |
cce855bc | 928 | The semicolon (or newline) following LIST is required. |
ccc6cda3 JA |
929 | |
930 | In addition to the creation of a subshell, there is a subtle | |
931 | difference between these two constructs due to historical reasons. The | |
932 | braces are `reserved words', so they must be separated from the LIST by | |
d7f49990 CR |
933 | `blank's or other shell metacharacters. The parentheses are |
934 | `operators', and are recognized as separate tokens by the shell even if | |
935 | they are not separated from the LIST by whitespace. | |
ccc6cda3 JA |
936 | |
937 | The exit status of both of these constructs is the exit status of | |
938 | LIST. | |
939 | ||
940 | \1f | |
cce855bc | 941 | File: bashref.info, Node: Shell Functions, Next: Shell Parameters, Prev: Shell Commands, Up: Basic Shell Features |
ccc6cda3 | 942 | |
37c41ab1 CR |
943 | 3.3 Shell Functions |
944 | =================== | |
ccc6cda3 | 945 | |
37c41ab1 CR |
946 | Shell functions are a way to group commands for later execution using a |
947 | single name for the group. They are executed just like a "regular" | |
948 | command. When the name of a shell function is used as a simple command | |
949 | name, the list of commands associated with that function name is | |
950 | executed. Shell functions are executed in the current shell context; | |
951 | no new process is created to interpret them. | |
ccc6cda3 | 952 | |
37c41ab1 | 953 | Functions are declared using this syntax: |
d3a24ed2 | 954 | [ `function' ] NAME () COMPOUND-COMMAND [ REDIRECTIONS ] |
ccc6cda3 JA |
955 | |
956 | This defines a shell function named NAME. The reserved word | |
cce855bc | 957 | `function' is optional. If the `function' reserved word is supplied, |
d3a24ed2 CR |
958 | the parentheses are optional. The BODY of the function is the compound |
959 | command COMPOUND-COMMAND (*note Compound Commands::). That command is | |
960 | usually a LIST enclosed between { and }, but may be any compound | |
961 | command listed above. COMPOUND-COMMAND is executed whenever NAME is | |
962 | specified as the name of a command. Any redirections (*note | |
963 | Redirections::) associated with the shell function are performed when | |
964 | the function is executed. | |
965 | ||
ac18b312 CR |
966 | A function definition may be deleted using the `-f' option to the |
967 | `unset' builtin (*note Bourne Shell Builtins::). | |
968 | ||
d3a24ed2 CR |
969 | The exit status of a function definition is zero unless a syntax |
970 | error occurs or a readonly function with the same name already exists. | |
971 | When executed, the exit status of a function is the exit status of the | |
972 | last command executed in the body. | |
973 | ||
974 | Note that for historical reasons, in the most common usage the curly | |
975 | braces that surround the body of the function must be separated from | |
976 | the body by `blank's or newlines. This is because the braces are | |
977 | reserved words and are only recognized as such when they are separated | |
d7f49990 CR |
978 | from the command list by whitespace or another shell metacharacter. |
979 | Also, when using the braces, the LIST must be terminated by a semicolon, | |
980 | a `&', or a newline. | |
bb70624e | 981 | |
ccc6cda3 JA |
982 | When a function is executed, the arguments to the function become |
983 | the positional parameters during its execution (*note Positional | |
28ef6c31 | 984 | Parameters::). The special parameter `#' that expands to the number of |
de8913bd | 985 | positional parameters is updated to reflect the change. Special |
d3a24ed2 CR |
986 | parameter `0' is unchanged. The first element of the `FUNCNAME' |
987 | variable is set to the name of the function while the function is | |
988 | executing. All other aspects of the shell execution environment are | |
989 | identical between a function and its caller with the exception that the | |
8fed3589 CR |
990 | `DEBUG' and `RETURN' traps are not inherited unless the function has |
991 | been given the `trace' attribute using the `declare' builtin or the `-o | |
992 | functrace' option has been enabled with the `set' builtin, (in which | |
993 | case all functions inherit the `DEBUG' and `RETURN' traps). *Note | |
994 | Bourne Shell Builtins::, for the description of the `trap' builtin. | |
ccc6cda3 JA |
995 | |
996 | If the builtin command `return' is executed in a function, the | |
997 | function completes and execution resumes with the next command after | |
d3a24ed2 CR |
998 | the function call. Any command associated with the `RETURN' trap is |
999 | executed before execution resumes. When a function completes, the | |
1000 | values of the positional parameters and the special parameter `#' are | |
1001 | restored to the values they had prior to the function's execution. If | |
1002 | a numeric argument is given to `return', that is the function's return | |
1003 | status; otherwise the function's return status is the exit status of | |
1004 | the last command executed before the `return'. | |
ccc6cda3 JA |
1005 | |
1006 | Variables local to the function may be declared with the `local' | |
1007 | builtin. These variables are visible only to the function and the | |
1008 | commands it invokes. | |
1009 | ||
d3a24ed2 CR |
1010 | Function names and definitions may be listed with the `-f' option to |
1011 | the `declare' or `typeset' builtin commands (*note Bash Builtins::). | |
1012 | The `-F' option to `declare' or `typeset' will list the function names | |
1013 | only (and optionally the source file and line number, if the `extdebug' | |
1014 | shell option is enabled). Functions may be exported so that subshells | |
1015 | automatically have them defined with the `-f' option to the `export' | |
1016 | builtin (*note Bourne Shell Builtins::). Note that shell functions and | |
1017 | variables with the same name may result in multiple identically-named | |
1018 | entries in the environment passed to the shell's children. Care should | |
1019 | be taken in cases where this may cause a problem. | |
1020 | ||
ccc6cda3 JA |
1021 | Functions may be recursive. No limit is placed on the number of |
1022 | recursive calls. | |
1023 | ||
1024 | \1f | |
1025 | File: bashref.info, Node: Shell Parameters, Next: Shell Expansions, Prev: Shell Functions, Up: Basic Shell Features | |
1026 | ||
37c41ab1 CR |
1027 | 3.4 Shell Parameters |
1028 | ==================== | |
ccc6cda3 JA |
1029 | |
1030 | * Menu: | |
1031 | ||
1032 | * Positional Parameters:: The shell's command-line arguments. | |
d3a24ed2 | 1033 | * Special Parameters:: Parameters denoted by special characters. |
ccc6cda3 JA |
1034 | |
1035 | A PARAMETER is an entity that stores values. It can be a `name', a | |
d3a24ed2 CR |
1036 | number, or one of the special characters listed below. A VARIABLE is a |
1037 | parameter denoted by a `name'. A variable has a VALUE and zero or more | |
1038 | ATTRIBUTES. Attributes are assigned using the `declare' builtin command | |
6a8fd0ed | 1039 | (see the description of the `declare' builtin in *note Bash Builtins::). |
ccc6cda3 JA |
1040 | |
1041 | A parameter is set if it has been assigned a value. The null string | |
1042 | is a valid value. Once a variable is set, it may be unset only by using | |
1043 | the `unset' builtin command. | |
1044 | ||
1045 | A variable may be assigned to by a statement of the form | |
1046 | NAME=[VALUE] | |
37c41ab1 | 1047 | If VALUE is not given, the variable is assigned the null string. All |
ccc6cda3 JA |
1048 | VALUEs undergo tilde expansion, parameter and variable expansion, |
1049 | command substitution, arithmetic expansion, and quote removal (detailed | |
f73dda09 | 1050 | below). If the variable has its `integer' attribute set, then VALUE is |
d3a24ed2 CR |
1051 | evaluated as an arithmetic expression even if the `$((...))' expansion |
1052 | is not used (*note Arithmetic Expansion::). Word splitting is not | |
1053 | performed, with the exception of `"$@"' as explained below. Filename | |
1054 | expansion is not performed. Assignment statements may also appear as | |
5e13499c CR |
1055 | arguments to the `alias', `declare', `typeset', `export', `readonly', |
1056 | and `local' builtin commands. | |
ccc6cda3 | 1057 | |
eb2bb562 CR |
1058 | In the context where an assignment statement is assigning a value to |
1059 | a shell variable or array index (*note Arrays::), the `+=' operator can | |
1060 | be used to append to or add to the variable's previous value. When | |
1061 | `+=' is applied to a variable for which the integer attribute has been | |
1062 | set, VALUE is evaluated as an arithmetic expression and added to the | |
1063 | variable's current value, which is also evaluated. When `+=' is | |
1064 | applied to an array variable using compound assignment (*note | |
1065 | Arrays::), the variable's value is not unset (as it is when using `='), | |
1066 | and new values are appended to the array beginning at one greater than | |
1067 | the array's maximum index. When applied to a string-valued variable, | |
1068 | VALUE is expanded and appended to the variable's value. | |
1069 | ||
ccc6cda3 JA |
1070 | \1f |
1071 | File: bashref.info, Node: Positional Parameters, Next: Special Parameters, Up: Shell Parameters | |
1072 | ||
37c41ab1 CR |
1073 | 3.4.1 Positional Parameters |
1074 | --------------------------- | |
ccc6cda3 | 1075 | |
37c41ab1 | 1076 | A POSITIONAL PARAMETER is a parameter denoted by one or more digits, |
ccc6cda3 JA |
1077 | other than the single digit `0'. Positional parameters are assigned |
1078 | from the shell's arguments when it is invoked, and may be reassigned | |
cce855bc | 1079 | using the `set' builtin command. Positional parameter `N' may be |
bb70624e JA |
1080 | referenced as `${N}', or as `$N' when `N' consists of a single digit. |
1081 | Positional parameters may not be assigned to with assignment statements. | |
1082 | The `set' and `shift' builtins are used to set and unset them (*note | |
28ef6c31 JA |
1083 | Shell Builtin Commands::). The positional parameters are temporarily |
1084 | replaced when a shell function is executed (*note Shell Functions::). | |
ccc6cda3 JA |
1085 | |
1086 | When a positional parameter consisting of more than a single digit | |
1087 | is expanded, it must be enclosed in braces. | |
1088 | ||
1089 | \1f | |
1090 | File: bashref.info, Node: Special Parameters, Prev: Positional Parameters, Up: Shell Parameters | |
1091 | ||
37c41ab1 CR |
1092 | 3.4.2 Special Parameters |
1093 | ------------------------ | |
ccc6cda3 | 1094 | |
37c41ab1 | 1095 | The shell treats several parameters specially. These parameters may |
ccc6cda3 JA |
1096 | only be referenced; assignment to them is not allowed. |
1097 | ||
1098 | `*' | |
1099 | Expands to the positional parameters, starting from one. When the | |
1100 | expansion occurs within double quotes, it expands to a single word | |
1101 | with the value of each parameter separated by the first character | |
1102 | of the `IFS' special variable. That is, `"$*"' is equivalent to | |
1103 | `"$1C$2C..."', where C is the first character of the value of the | |
d166f048 JA |
1104 | `IFS' variable. If `IFS' is unset, the parameters are separated |
1105 | by spaces. If `IFS' is null, the parameters are joined without | |
1106 | intervening separators. | |
ccc6cda3 JA |
1107 | |
1108 | `@' | |
1109 | Expands to the positional parameters, starting from one. When the | |
cce855bc | 1110 | expansion occurs within double quotes, each parameter expands to a |
ccc6cda3 | 1111 | separate word. That is, `"$@"' is equivalent to `"$1" "$2" ...'. |
37c41ab1 CR |
1112 | If the double-quoted expansion occurs within a word, the expansion |
1113 | of the first parameter is joined with the beginning part of the | |
1114 | original word, and the expansion of the last parameter is joined | |
1115 | with the last part of the original word. When there are no | |
1116 | positional parameters, `"$@"' and `$@' expand to nothing (i.e., | |
1117 | they are removed). | |
ccc6cda3 JA |
1118 | |
1119 | `#' | |
1120 | Expands to the number of positional parameters in decimal. | |
1121 | ||
1122 | `?' | |
1123 | Expands to the exit status of the most recently executed foreground | |
1124 | pipeline. | |
1125 | ||
1126 | `-' | |
bb70624e JA |
1127 | (A hyphen.) Expands to the current option flags as specified upon |
1128 | invocation, by the `set' builtin command, or those set by the | |
1129 | shell itself (such as the `-i' option). | |
ccc6cda3 JA |
1130 | |
1131 | `$' | |
1132 | Expands to the process ID of the shell. In a `()' subshell, it | |
cce855bc | 1133 | expands to the process ID of the invoking shell, not the subshell. |
ccc6cda3 JA |
1134 | |
1135 | `!' | |
1136 | Expands to the process ID of the most recently executed background | |
1137 | (asynchronous) command. | |
1138 | ||
1139 | `0' | |
1140 | Expands to the name of the shell or shell script. This is set at | |
cce855bc | 1141 | shell initialization. If Bash is invoked with a file of commands |
28ef6c31 JA |
1142 | (*note Shell Scripts::), `$0' is set to the name of that file. If |
1143 | Bash is started with the `-c' option (*note Invoking Bash::), then | |
1144 | `$0' is set to the first argument after the string to be executed, | |
1145 | if one is present. Otherwise, it is set to the filename used to | |
1146 | invoke Bash, as given by argument zero. | |
ccc6cda3 JA |
1147 | |
1148 | `_' | |
2206f89a CR |
1149 | (An underscore.) At shell startup, set to the absolute pathname |
1150 | used to invoke the shell or shell script being executed as passed | |
1151 | in the environment or argument list. Subsequently, expands to the | |
1152 | last argument to the previous command, after expansion. Also set | |
1153 | to the full pathname used to invoke each command executed and | |
1154 | placed in the environment exported to that command. When checking | |
1155 | mail, this parameter holds the name of the mail file. | |
ccc6cda3 JA |
1156 | |
1157 | \1f | |
1158 | File: bashref.info, Node: Shell Expansions, Next: Redirections, Prev: Shell Parameters, Up: Basic Shell Features | |
1159 | ||
37c41ab1 CR |
1160 | 3.5 Shell Expansions |
1161 | ==================== | |
ccc6cda3 | 1162 | |
37c41ab1 CR |
1163 | Expansion is performed on the command line after it has been split into |
1164 | `token's. There are seven kinds of expansion performed: | |
ccc6cda3 JA |
1165 | * brace expansion |
1166 | ||
1167 | * tilde expansion | |
1168 | ||
1169 | * parameter and variable expansion | |
1170 | ||
1171 | * command substitution | |
1172 | ||
1173 | * arithmetic expansion | |
1174 | ||
1175 | * word splitting | |
1176 | ||
1177 | * filename expansion | |
1178 | ||
1179 | * Menu: | |
1180 | ||
cce855bc JA |
1181 | * Brace Expansion:: Expansion of expressions within braces. |
1182 | * Tilde Expansion:: Expansion of the ~ character. | |
ccc6cda3 JA |
1183 | * Shell Parameter Expansion:: How Bash expands variables to their values. |
1184 | * Command Substitution:: Using the output of a command as an argument. | |
cce855bc | 1185 | * Arithmetic Expansion:: How to use arithmetic in shell expansions. |
ccc6cda3 JA |
1186 | * Process Substitution:: A way to write and read to and from a |
1187 | command. | |
1188 | * Word Splitting:: How the results of expansion are split into separate | |
1189 | arguments. | |
1190 | * Filename Expansion:: A shorthand for specifying filenames matching patterns. | |
1191 | * Quote Removal:: How and when quote characters are removed from | |
1192 | words. | |
1193 | ||
ccc6cda3 JA |
1194 | The order of expansions is: brace expansion, tilde expansion, |
1195 | parameter, variable, and arithmetic expansion and command substitution | |
1196 | (done in a left-to-right fashion), word splitting, and filename | |
1197 | expansion. | |
1198 | ||
1199 | On systems that can support it, there is an additional expansion | |
1200 | available: PROCESS SUBSTITUTION. This is performed at the same time as | |
cce855bc | 1201 | parameter, variable, and arithmetic expansion and command substitution. |
ccc6cda3 JA |
1202 | |
1203 | Only brace expansion, word splitting, and filename expansion can | |
1204 | change the number of words of the expansion; other expansions expand a | |
1205 | single word to a single word. The only exceptions to this are the | |
28ef6c31 JA |
1206 | expansions of `"$@"' (*note Special Parameters::) and `"${NAME[@]}"' |
1207 | (*note Arrays::). | |
ccc6cda3 | 1208 | |
28ef6c31 | 1209 | After all expansions, `quote removal' (*note Quote Removal::) is |
ccc6cda3 JA |
1210 | performed. |
1211 | ||
1212 | \1f | |
cce855bc JA |
1213 | File: bashref.info, Node: Brace Expansion, Next: Tilde Expansion, Up: Shell Expansions |
1214 | ||
37c41ab1 CR |
1215 | 3.5.1 Brace Expansion |
1216 | --------------------- | |
cce855bc | 1217 | |
37c41ab1 | 1218 | Brace expansion is a mechanism by which arbitrary strings may be |
cce855bc | 1219 | generated. This mechanism is similar to FILENAME EXPANSION (*note |
28ef6c31 | 1220 | Filename Expansion::), but the file names generated need not exist. |
cce855bc | 1221 | Patterns to be brace expanded take the form of an optional PREAMBLE, |
d3ad40de | 1222 | followed by either a series of comma-separated strings or a seqeunce |
d3a24ed2 CR |
1223 | expression between a pair of braces, followed by an optional POSTSCRIPT. |
1224 | The preamble is prefixed to each string contained within the braces, and | |
1225 | the postscript is then appended to each resulting string, expanding left | |
1226 | to right. | |
cce855bc JA |
1227 | |
1228 | Brace expansions may be nested. The results of each expanded string | |
1229 | are not sorted; left to right order is preserved. For example, | |
1230 | bash$ echo a{d,c,b}e | |
1231 | ade ace abe | |
1232 | ||
ed35cb4a CR |
1233 | A sequence expression takes the form `{X..Y[INCR]}', where X and Y |
1234 | are either integers or single characters, and INCR, an optional | |
1235 | increment, is an integer. When integers are supplied, the expression | |
1236 | expands to each number between X and Y, inclusive. Supplied integers | |
1237 | may be prefixed with `0' to force each term to have the same width. | |
1238 | When either X or Y begins with a zero, the shell attempts to force all | |
1239 | generated terms to contain the same number of digits, zero-padding | |
1240 | where necessary. When characters are supplied, the expression expands | |
1241 | to each character lexicographically between X and Y, inclusive. Note | |
1242 | that both X and Y must be of the same type. When the increment is | |
1243 | supplied, it is used as the difference between each term. The default | |
1244 | increment is 1 or -1 as appropriate. | |
d3a24ed2 | 1245 | |
cce855bc JA |
1246 | Brace expansion is performed before any other expansions, and any |
1247 | characters special to other expansions are preserved in the result. It | |
1248 | is strictly textual. Bash does not apply any syntactic interpretation | |
bb70624e JA |
1249 | to the context of the expansion or the text between the braces. To |
1250 | avoid conflicts with parameter expansion, the string `${' is not | |
1251 | considered eligible for brace expansion. | |
cce855bc JA |
1252 | |
1253 | A correctly-formed brace expansion must contain unquoted opening and | |
d3a24ed2 CR |
1254 | closing braces, and at least one unquoted comma or a valid sequence |
1255 | expression. Any incorrectly formed brace expansion is left unchanged. | |
1256 | ||
1257 | A { or `,' may be quoted with a backslash to prevent its being | |
1258 | considered part of a brace expression. To avoid conflicts with | |
1259 | parameter expansion, the string `${' is not considered eligible for | |
1260 | brace expansion. | |
cce855bc JA |
1261 | |
1262 | This construct is typically used as shorthand when the common prefix | |
1263 | of the strings to be generated is longer than in the above example: | |
1264 | mkdir /usr/local/src/bash/{old,new,dist,bugs} | |
1265 | or | |
1266 | chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}} | |
1267 | ||
1268 | \1f | |
1269 | File: bashref.info, Node: Tilde Expansion, Next: Shell Parameter Expansion, Prev: Brace Expansion, Up: Shell Expansions | |
1270 | ||
37c41ab1 CR |
1271 | 3.5.2 Tilde Expansion |
1272 | --------------------- | |
cce855bc | 1273 | |
37c41ab1 | 1274 | If a word begins with an unquoted tilde character (`~'), all of the |
cce855bc JA |
1275 | characters up to the first unquoted slash (or all characters, if there |
1276 | is no unquoted slash) are considered a TILDE-PREFIX. If none of the | |
1277 | characters in the tilde-prefix are quoted, the characters in the | |
1278 | tilde-prefix following the tilde are treated as a possible LOGIN NAME. | |
1279 | If this login name is the null string, the tilde is replaced with the | |
1280 | value of the `HOME' shell variable. If `HOME' is unset, the home | |
1281 | directory of the user executing the shell is substituted instead. | |
1282 | Otherwise, the tilde-prefix is replaced with the home directory | |
1283 | associated with the specified login name. | |
1284 | ||
1285 | If the tilde-prefix is `~+', the value of the shell variable `PWD' | |
1286 | replaces the tilde-prefix. If the tilde-prefix is `~-', the value of | |
1287 | the shell variable `OLDPWD', if it is set, is substituted. | |
1288 | ||
1289 | If the characters following the tilde in the tilde-prefix consist of | |
1290 | a number N, optionally prefixed by a `+' or a `-', the tilde-prefix is | |
1291 | replaced with the corresponding element from the directory stack, as it | |
1292 | would be displayed by the `dirs' builtin invoked with the characters | |
1293 | following tilde in the tilde-prefix as an argument (*note The Directory | |
28ef6c31 | 1294 | Stack::). If the tilde-prefix, sans the tilde, consists of a number |
cce855bc JA |
1295 | without a leading `+' or `-', `+' is assumed. |
1296 | ||
1297 | If the login name is invalid, or the tilde expansion fails, the word | |
1298 | is left unchanged. | |
1299 | ||
1300 | Each variable assignment is checked for unquoted tilde-prefixes | |
eb2bb562 CR |
1301 | immediately following a `:' or the first `='. In these cases, tilde |
1302 | expansion is also performed. Consequently, one may use file names with | |
1303 | tildes in assignments to `PATH', `MAILPATH', and `CDPATH', and the | |
1304 | shell assigns the expanded value. | |
cce855bc JA |
1305 | |
1306 | The following table shows how Bash treats unquoted tilde-prefixes: | |
1307 | ||
1308 | `~' | |
1309 | The value of `$HOME' | |
1310 | ||
1311 | `~/foo' | |
1312 | `$HOME/foo' | |
1313 | ||
1314 | `~fred/foo' | |
1315 | The subdirectory `foo' of the home directory of the user `fred' | |
1316 | ||
1317 | `~+/foo' | |
1318 | `$PWD/foo' | |
1319 | ||
1320 | `~-/foo' | |
1321 | `${OLDPWD-'~-'}/foo' | |
1322 | ||
1323 | `~N' | |
1324 | The string that would be displayed by `dirs +N' | |
1325 | ||
1326 | `~+N' | |
1327 | The string that would be displayed by `dirs +N' | |
1328 | ||
1329 | `~-N' | |
1330 | The string that would be displayed by `dirs -N' | |
1331 | ||
761783bf | 1332 | |
cce855bc JA |
1333 | \1f |
1334 | File: bashref.info, Node: Shell Parameter Expansion, Next: Command Substitution, Prev: Tilde Expansion, Up: Shell Expansions | |
ccc6cda3 | 1335 | |
37c41ab1 CR |
1336 | 3.5.3 Shell Parameter Expansion |
1337 | ------------------------------- | |
ccc6cda3 | 1338 | |
37c41ab1 CR |
1339 | The `$' character introduces parameter expansion, command substitution, |
1340 | or arithmetic expansion. The parameter name or symbol to be expanded | |
1341 | may be enclosed in braces, which are optional but serve to protect the | |
1342 | variable to be expanded from characters immediately following it which | |
1343 | could be interpreted as part of the name. | |
ccc6cda3 | 1344 | |
cce855bc JA |
1345 | When braces are used, the matching ending brace is the first `}' not |
1346 | escaped by a backslash or within a quoted string, and not within an | |
1347 | embedded arithmetic expansion, command substitution, or parameter | |
1348 | expansion. | |
1349 | ||
ccc6cda3 JA |
1350 | The basic form of parameter expansion is ${PARAMETER}. The value of |
1351 | PARAMETER is substituted. The braces are required when PARAMETER is a | |
1352 | positional parameter with more than one digit, or when PARAMETER is | |
1353 | followed by a character that is not to be interpreted as part of its | |
1354 | name. | |
1355 | ||
1356 | If the first character of PARAMETER is an exclamation point, a level | |
1357 | of variable indirection is introduced. Bash uses the value of the | |
1358 | variable formed from the rest of PARAMETER as the name of the variable; | |
d166f048 JA |
1359 | this variable is then expanded and that value is used in the rest of |
1360 | the substitution, rather than the value of PARAMETER itself. This is | |
d3a24ed2 CR |
1361 | known as `indirect expansion'. The exceptions to this are the |
1362 | expansions of ${!PREFIX*} and ${!NAME[@]} described below. The | |
1363 | exclamation point must immediately follow the left brace in order to | |
1364 | introduce indirection. | |
ccc6cda3 JA |
1365 | |
1366 | In each of the cases below, WORD is subject to tilde expansion, | |
1367 | parameter expansion, command substitution, and arithmetic expansion. | |
bb70624e JA |
1368 | |
1369 | When not performing substring expansion, Bash tests for a parameter | |
ccc6cda3 | 1370 | that is unset or null; omitting the colon results in a test only for a |
bb70624e JA |
1371 | parameter that is unset. Put another way, if the colon is included, |
1372 | the operator tests for both existence and that the value is not null; | |
1373 | if the colon is omitted, the operator tests only for existence. | |
ccc6cda3 JA |
1374 | |
1375 | `${PARAMETER:-WORD}' | |
1376 | If PARAMETER is unset or null, the expansion of WORD is | |
1377 | substituted. Otherwise, the value of PARAMETER is substituted. | |
1378 | ||
1379 | `${PARAMETER:=WORD}' | |
1380 | If PARAMETER is unset or null, the expansion of WORD is assigned | |
1381 | to PARAMETER. The value of PARAMETER is then substituted. | |
de8913bd CR |
1382 | Positional parameters and special parameters may not be assigned to |
1383 | in this way. | |
ccc6cda3 JA |
1384 | |
1385 | `${PARAMETER:?WORD}' | |
1386 | If PARAMETER is null or unset, the expansion of WORD (or a message | |
1387 | to that effect if WORD is not present) is written to the standard | |
1388 | error and the shell, if it is not interactive, exits. Otherwise, | |
1389 | the value of PARAMETER is substituted. | |
1390 | ||
1391 | `${PARAMETER:+WORD}' | |
1392 | If PARAMETER is null or unset, nothing is substituted, otherwise | |
1393 | the expansion of WORD is substituted. | |
1394 | ||
1395 | `${PARAMETER:OFFSET}' | |
1396 | `${PARAMETER:OFFSET:LENGTH}' | |
bb70624e | 1397 | Expands to up to LENGTH characters of PARAMETER starting at the |
cce855bc | 1398 | character specified by OFFSET. If LENGTH is omitted, expands to |
bb70624e | 1399 | the substring of PARAMETER starting at the character specified by |
cce855bc | 1400 | OFFSET. LENGTH and OFFSET are arithmetic expressions (*note Shell |
28ef6c31 | 1401 | Arithmetic::). This is referred to as Substring Expansion. |
ccc6cda3 JA |
1402 | |
1403 | LENGTH must evaluate to a number greater than or equal to zero. | |
1404 | If OFFSET evaluates to a number less than zero, the value is used | |
1405 | as an offset from the end of the value of PARAMETER. If PARAMETER | |
1406 | is `@', the result is LENGTH positional parameters beginning at | |
1407 | OFFSET. If PARAMETER is an array name indexed by `@' or `*', the | |
1408 | result is the LENGTH members of the array beginning with | |
eb2bb562 CR |
1409 | `${PARAMETER[OFFSET]}'. A negative OFFSET is taken relative to |
1410 | one greater than the maximum index of the specified array. Note | |
1411 | that a negative offset must be separated from the colon by at least | |
1412 | one space to avoid being confused with the `:-' expansion. | |
1413 | Substring indexing is zero-based unless the positional parameters | |
d3ad40de CR |
1414 | are used, in which case the indexing starts at 1 by default. If |
1415 | OFFSET is 0, and the positional parameters are used, `$@' is | |
1416 | prefixed to the list. | |
ccc6cda3 | 1417 | |
bb70624e | 1418 | `${!PREFIX*}' |
d3a24ed2 | 1419 | `${!PREFIX@}' |
bb70624e JA |
1420 | Expands to the names of variables whose names begin with PREFIX, |
1421 | separated by the first character of the `IFS' special variable. | |
d3ad40de CR |
1422 | When `@' is used and the expansion appears within double quotes, |
1423 | each variable name expands to a separate word. | |
bb70624e | 1424 | |
d3a24ed2 CR |
1425 | `${!NAME[@]}' |
1426 | `${!NAME[*]}' | |
1427 | If NAME is an array variable, expands to the list of array indices | |
1428 | (keys) assigned in NAME. If NAME is not an array, expands to 0 if | |
1429 | NAME is set and null otherwise. When `@' is used and the | |
1430 | expansion appears within double quotes, each key expands to a | |
1431 | separate word. | |
1432 | ||
ccc6cda3 | 1433 | `${#PARAMETER}' |
cce855bc JA |
1434 | The length in characters of the expanded value of PARAMETER is |
1435 | substituted. If PARAMETER is `*' or `@', the value substituted is | |
1436 | the number of positional parameters. If PARAMETER is an array | |
1437 | name subscripted by `*' or `@', the value substituted is the | |
1438 | number of elements in the array. | |
ccc6cda3 JA |
1439 | |
1440 | `${PARAMETER#WORD}' | |
1441 | `${PARAMETER##WORD}' | |
1442 | The WORD is expanded to produce a pattern just as in filename | |
28ef6c31 | 1443 | expansion (*note Filename Expansion::). If the pattern matches |
cce855bc JA |
1444 | the beginning of the expanded value of PARAMETER, then the result |
1445 | of the expansion is the expanded value of PARAMETER with the | |
1446 | shortest matching pattern (the `#' case) or the longest matching | |
1447 | pattern (the `##' case) deleted. If PARAMETER is `@' or `*', the | |
1448 | pattern removal operation is applied to each positional parameter | |
1449 | in turn, and the expansion is the resultant list. If PARAMETER is | |
1450 | an array variable subscripted with `@' or `*', the pattern removal | |
1451 | operation is applied to each member of the array in turn, and the | |
1452 | expansion is the resultant list. | |
ccc6cda3 JA |
1453 | |
1454 | `${PARAMETER%WORD}' | |
1455 | `${PARAMETER%%WORD}' | |
1456 | The WORD is expanded to produce a pattern just as in filename | |
cce855bc JA |
1457 | expansion. If the pattern matches a trailing portion of the |
1458 | expanded value of PARAMETER, then the result of the expansion is | |
1459 | the value of PARAMETER with the shortest matching pattern (the `%' | |
1460 | case) or the longest matching pattern (the `%%' case) deleted. If | |
1461 | PARAMETER is `@' or `*', the pattern removal operation is applied | |
1462 | to each positional parameter in turn, and the expansion is the | |
1463 | resultant list. If PARAMETER is an array variable subscripted | |
1464 | with `@' or `*', the pattern removal operation is applied to each | |
1465 | member of the array in turn, and the expansion is the resultant | |
1466 | list. | |
ccc6cda3 JA |
1467 | |
1468 | `${PARAMETER/PATTERN/STRING}' | |
ccc6cda3 JA |
1469 | The PATTERN is expanded to produce a pattern just as in filename |
1470 | expansion. PARAMETER is expanded and the longest match of PATTERN | |
ac18b312 CR |
1471 | against its value is replaced with STRING. If PATTERN begins with |
1472 | `/', all matches of PATTERN are replaced with STRING. Normally | |
1473 | only the first match is replaced. If PATTERN begins with `#', it | |
1474 | must match at the beginning of the expanded value of PARAMETER. | |
1475 | If PATTERN begins with `%', it must match at the end of the | |
1476 | expanded value of PARAMETER. If STRING is null, matches of | |
b72432fd JA |
1477 | PATTERN are deleted and the `/' following PATTERN may be omitted. |
1478 | If PARAMETER is `@' or `*', the substitution operation is applied | |
1479 | to each positional parameter in turn, and the expansion is the | |
1480 | resultant list. If PARAMETER is an array variable subscripted | |
1481 | with `@' or `*', the substitution operation is applied to each | |
1482 | member of the array in turn, and the expansion is the resultant | |
1483 | list. | |
ccc6cda3 | 1484 | |
761783bf | 1485 | |
ccc6cda3 | 1486 | \1f |
cce855bc | 1487 | File: bashref.info, Node: Command Substitution, Next: Arithmetic Expansion, Prev: Shell Parameter Expansion, Up: Shell Expansions |
ccc6cda3 | 1488 | |
37c41ab1 CR |
1489 | 3.5.4 Command Substitution |
1490 | -------------------------- | |
ccc6cda3 | 1491 | |
37c41ab1 | 1492 | Command substitution allows the output of a command to replace the |
bb70624e JA |
1493 | command itself. Command substitution occurs when a command is enclosed |
1494 | as follows: | |
ccc6cda3 | 1495 | $(COMMAND) |
37c41ab1 | 1496 | or |
ccc6cda3 JA |
1497 | `COMMAND` |
1498 | ||
1499 | Bash performs the expansion by executing COMMAND and replacing the | |
1500 | command substitution with the standard output of the command, with any | |
cce855bc JA |
1501 | trailing newlines deleted. Embedded newlines are not deleted, but they |
1502 | may be removed during word splitting. The command substitution `$(cat | |
1503 | FILE)' can be replaced by the equivalent but faster `$(< FILE)'. | |
ccc6cda3 JA |
1504 | |
1505 | When the old-style backquote form of substitution is used, backslash | |
1506 | retains its literal meaning except when followed by `$', ``', or `\'. | |
cce855bc JA |
1507 | The first backquote not preceded by a backslash terminates the command |
1508 | substitution. When using the `$(COMMAND)' form, all characters between | |
1509 | the parentheses make up the command; none are treated specially. | |
ccc6cda3 | 1510 | |
cce855bc JA |
1511 | Command substitutions may be nested. To nest when using the |
1512 | backquoted form, escape the inner backquotes with backslashes. | |
ccc6cda3 JA |
1513 | |
1514 | If the substitution appears within double quotes, word splitting and | |
1515 | filename expansion are not performed on the results. | |
1516 | ||
1517 | \1f | |
cce855bc JA |
1518 | File: bashref.info, Node: Arithmetic Expansion, Next: Process Substitution, Prev: Command Substitution, Up: Shell Expansions |
1519 | ||
37c41ab1 CR |
1520 | 3.5.5 Arithmetic Expansion |
1521 | -------------------------- | |
cce855bc | 1522 | |
37c41ab1 CR |
1523 | Arithmetic expansion allows the evaluation of an arithmetic expression |
1524 | and the substitution of the result. The format for arithmetic | |
1525 | expansion is: | |
cce855bc JA |
1526 | |
1527 | $(( EXPRESSION )) | |
1528 | ||
1529 | The expression is treated as if it were within double quotes, but a | |
1530 | double quote inside the parentheses is not treated specially. All | |
1531 | tokens in the expression undergo parameter expansion, command | |
d3a24ed2 | 1532 | substitution, and quote removal. Arithmetic expansions may be nested. |
cce855bc JA |
1533 | |
1534 | The evaluation is performed according to the rules listed below | |
28ef6c31 | 1535 | (*note Shell Arithmetic::). If the expression is invalid, Bash prints |
cce855bc JA |
1536 | a message indicating failure to the standard error and no substitution |
1537 | occurs. | |
1538 | ||
1539 | \1f | |
1540 | File: bashref.info, Node: Process Substitution, Next: Word Splitting, Prev: Arithmetic Expansion, Up: Shell Expansions | |
ccc6cda3 | 1541 | |
37c41ab1 CR |
1542 | 3.5.6 Process Substitution |
1543 | -------------------------- | |
ccc6cda3 | 1544 | |
37c41ab1 CR |
1545 | Process substitution is supported on systems that support named pipes |
1546 | (FIFOs) or the `/dev/fd' method of naming open files. It takes the | |
1547 | form of | |
ccc6cda3 | 1548 | <(LIST) |
37c41ab1 | 1549 | or |
ccc6cda3 | 1550 | >(LIST) |
37c41ab1 CR |
1551 | The process LIST is run with its input or output connected to a FIFO |
1552 | or some file in `/dev/fd'. The name of this file is passed as an | |
1553 | argument to the current command as the result of the expansion. If the | |
ccc6cda3 JA |
1554 | `>(LIST)' form is used, writing to the file will provide input for |
1555 | LIST. If the `<(LIST)' form is used, the file passed as an argument | |
bb70624e JA |
1556 | should be read to obtain the output of LIST. Note that no space may |
1557 | appear between the `<' or `>' and the left parenthesis, otherwise the | |
1558 | construct would be interpreted as a redirection. | |
ccc6cda3 | 1559 | |
cce855bc JA |
1560 | When available, process substitution is performed simultaneously with |
1561 | parameter and variable expansion, command substitution, and arithmetic | |
1562 | expansion. | |
ccc6cda3 JA |
1563 | |
1564 | \1f | |
1565 | File: bashref.info, Node: Word Splitting, Next: Filename Expansion, Prev: Process Substitution, Up: Shell Expansions | |
1566 | ||
37c41ab1 CR |
1567 | 3.5.7 Word Splitting |
1568 | -------------------- | |
ccc6cda3 | 1569 | |
37c41ab1 | 1570 | The shell scans the results of parameter expansion, command |
ccc6cda3 JA |
1571 | substitution, and arithmetic expansion that did not occur within double |
1572 | quotes for word splitting. | |
1573 | ||
1574 | The shell treats each character of `$IFS' as a delimiter, and splits | |
1575 | the results of the other expansions into words on these characters. If | |
1576 | `IFS' is unset, or its value is exactly `<space><tab><newline>', the | |
d3ad40de CR |
1577 | default, then sequences of ` <space>', `<tab>', and `<newline>' at the |
1578 | beginning and end of the results of the previous expansions are | |
1579 | ignored, and any sequence of `IFS' characters not at the beginning or | |
1580 | end serves to delimit words. If `IFS' has a value other than the | |
1581 | default, then sequences of the whitespace characters `space' and `tab' | |
1582 | are ignored at the beginning and end of the word, as long as the | |
1583 | whitespace character is in the value of `IFS' (an `IFS' whitespace | |
1584 | character). Any character in `IFS' that is not `IFS' whitespace, along | |
1585 | with any adjacent `IFS' whitespace characters, delimits a field. A | |
1586 | sequence of `IFS' whitespace characters is also treated as a delimiter. | |
1587 | If the value of `IFS' is null, no word splitting occurs. | |
ccc6cda3 JA |
1588 | |
1589 | Explicit null arguments (`""' or `''') are retained. Unquoted | |
bb70624e | 1590 | implicit null arguments, resulting from the expansion of parameters |
ccc6cda3 JA |
1591 | that have no values, are removed. If a parameter with no value is |
1592 | expanded within double quotes, a null argument results and is retained. | |
1593 | ||
1594 | Note that if no expansion occurs, no splitting is performed. | |
1595 | ||
1596 | \1f | |
1597 | File: bashref.info, Node: Filename Expansion, Next: Quote Removal, Prev: Word Splitting, Up: Shell Expansions | |
1598 | ||
37c41ab1 CR |
1599 | 3.5.8 Filename Expansion |
1600 | ------------------------ | |
ccc6cda3 | 1601 | |
cce855bc JA |
1602 | * Menu: |
1603 | ||
1604 | * Pattern Matching:: How the shell matches patterns. | |
1605 | ||
ccc6cda3 | 1606 | After word splitting, unless the `-f' option has been set (*note The |
28ef6c31 | 1607 | Set Builtin::), Bash scans each word for the characters `*', `?', and |
bb70624e JA |
1608 | `['. If one of these characters appears, then the word is regarded as |
1609 | a PATTERN, and replaced with an alphabetically sorted list of file | |
ccc6cda3 | 1610 | names matching the pattern. If no matching file names are found, and |
cce855bc JA |
1611 | the shell option `nullglob' is disabled, the word is left unchanged. |
1612 | If the `nullglob' option is set, and no matches are found, the word is | |
5e13499c CR |
1613 | removed. If the `failglob' shell option is set, and no matches are |
1614 | found, an error message is printed and the command is not executed. If | |
1615 | the shell option `nocaseglob' is enabled, the match is performed | |
1616 | without regard to the case of alphabetic characters. | |
cce855bc | 1617 | |
28ef6c31 JA |
1618 | When a pattern is used for filename generation, the character `.' at |
1619 | the start of a filename or immediately following a slash must be | |
cce855bc JA |
1620 | matched explicitly, unless the shell option `dotglob' is set. When |
1621 | matching a file name, the slash character must always be matched | |
1622 | explicitly. In other cases, the `.' character is not treated specially. | |
1623 | ||
6a8fd0ed | 1624 | See the description of `shopt' in *note The Shopt Builtin::, for a |
5e13499c CR |
1625 | description of the `nocaseglob', `nullglob', `failglob', and `dotglob' |
1626 | options. | |
ccc6cda3 JA |
1627 | |
1628 | The `GLOBIGNORE' shell variable may be used to restrict the set of | |
cce855bc | 1629 | filenames matching a pattern. If `GLOBIGNORE' is set, each matching |
ccc6cda3 | 1630 | filename that also matches one of the patterns in `GLOBIGNORE' is |
28ef6c31 | 1631 | removed from the list of matches. The filenames `.' and `..' are |
d3a24ed2 CR |
1632 | always ignored when `GLOBIGNORE' is set and not null. However, setting |
1633 | `GLOBIGNORE' to a non-null value has the effect of enabling the | |
1634 | `dotglob' shell option, so all other filenames beginning with a `.' | |
1635 | will match. To get the old behavior of ignoring filenames beginning | |
1636 | with a `.', make `.*' one of the patterns in `GLOBIGNORE'. The | |
1637 | `dotglob' option is disabled when `GLOBIGNORE' is unset. | |
ccc6cda3 | 1638 | |
cce855bc JA |
1639 | \1f |
1640 | File: bashref.info, Node: Pattern Matching, Up: Filename Expansion | |
1641 | ||
37c41ab1 CR |
1642 | 3.5.8.1 Pattern Matching |
1643 | ........................ | |
cce855bc | 1644 | |
37c41ab1 CR |
1645 | Any character that appears in a pattern, other than the special pattern |
1646 | characters described below, matches itself. The NUL character may not | |
1647 | occur in a pattern. A backslash escapes the following character; the | |
1648 | escaping backslash is discarded when matching. The special pattern | |
1649 | characters must be quoted if they are to be matched literally. | |
cce855bc | 1650 | |
ccc6cda3 JA |
1651 | The special pattern characters have the following meanings: |
1652 | `*' | |
ed35cb4a CR |
1653 | Matches any string, including the null string. When the |
1654 | `globstar' shell option is enabled, and `*' is used in a filename | |
1655 | expansion context, two adjacent `*'s used as a single pattern will | |
1656 | match all files and zero or more directories and subdirectories. | |
1657 | If followed by a `/', two adjacent `*'s will match only | |
1658 | directories and subdirectories. | |
ccc6cda3 JA |
1659 | |
1660 | `?' | |
1661 | Matches any single character. | |
1662 | ||
1663 | `[...]' | |
1664 | Matches any one of the enclosed characters. A pair of characters | |
28ef6c31 JA |
1665 | separated by a hyphen denotes a RANGE EXPRESSION; any character |
1666 | that sorts between those two characters, inclusive, using the | |
1667 | current locale's collating sequence and character set, is matched. | |
1668 | If the first character following the `[' is a `!' or a `^' then | |
1669 | any character not enclosed is matched. A `-' may be matched by | |
1670 | including it as the first or last character in the set. A `]' may | |
1671 | be matched by including it as the first character in the set. The | |
1672 | sorting order of characters in range expressions is determined by | |
1673 | the current locale and the value of the `LC_COLLATE' shell | |
1674 | variable, if set. | |
1675 | ||
1676 | For example, in the default C locale, `[a-dx-z]' is equivalent to | |
1677 | `[abcdxyz]'. Many locales sort characters in dictionary order, | |
1678 | and in these locales `[a-dx-z]' is typically not equivalent to | |
1679 | `[abcdxyz]'; it might be equivalent to `[aBbCcDdxXyYz]', for | |
1680 | example. To obtain the traditional interpretation of ranges in | |
1681 | bracket expressions, you can force the use of the C locale by | |
1682 | setting the `LC_COLLATE' or `LC_ALL' environment variable to the | |
1683 | value `C'. | |
ccc6cda3 | 1684 | |
cce855bc JA |
1685 | Within `[' and `]', CHARACTER CLASSES can be specified using the |
1686 | syntax `[:'CLASS`:]', where CLASS is one of the following classes | |
ac18b312 | 1687 | defined in the POSIX standard: |
cce855bc | 1688 | alnum alpha ascii blank cntrl digit graph lower |
7117c2d2 | 1689 | print punct space upper word xdigit |
cce855bc | 1690 | A character class matches any character belonging to that class. |
7117c2d2 JA |
1691 | The `word' character class matches letters, digits, and the |
1692 | character `_'. | |
cce855bc JA |
1693 | |
1694 | Within `[' and `]', an EQUIVALENCE CLASS can be specified using | |
1695 | the syntax `[='C`=]', which matches all characters with the same | |
1696 | collation weight (as defined by the current locale) as the | |
1697 | character C. | |
1698 | ||
28ef6c31 | 1699 | Within `[' and `]', the syntax `[.'SYMBOL`.]' matches the |
cce855bc JA |
1700 | collating symbol SYMBOL. |
1701 | ||
1702 | If the `extglob' shell option is enabled using the `shopt' builtin, | |
1703 | several extended pattern matching operators are recognized. In the | |
1704 | following description, a PATTERN-LIST is a list of one or more patterns | |
1705 | separated by a `|'. Composite patterns may be formed using one or more | |
1706 | of the following sub-patterns: | |
1707 | ||
1708 | `?(PATTERN-LIST)' | |
1709 | Matches zero or one occurrence of the given patterns. | |
1710 | ||
1711 | `*(PATTERN-LIST)' | |
1712 | Matches zero or more occurrences of the given patterns. | |
1713 | ||
1714 | `+(PATTERN-LIST)' | |
1715 | Matches one or more occurrences of the given patterns. | |
1716 | ||
1717 | `@(PATTERN-LIST)' | |
eb2bb562 | 1718 | Matches one of the given patterns. |
cce855bc JA |
1719 | |
1720 | `!(PATTERN-LIST)' | |
1721 | Matches anything except one of the given patterns. | |
1722 | ||
ccc6cda3 JA |
1723 | \1f |
1724 | File: bashref.info, Node: Quote Removal, Prev: Filename Expansion, Up: Shell Expansions | |
1725 | ||
37c41ab1 CR |
1726 | 3.5.9 Quote Removal |
1727 | ------------------- | |
ccc6cda3 | 1728 | |
37c41ab1 | 1729 | After the preceding expansions, all unquoted occurrences of the |
ccc6cda3 JA |
1730 | characters `\', `'', and `"' that did not result from one of the above |
1731 | expansions are removed. | |
1732 | ||
1733 | \1f | |
1734 | File: bashref.info, Node: Redirections, Next: Executing Commands, Prev: Shell Expansions, Up: Basic Shell Features | |
1735 | ||
37c41ab1 CR |
1736 | 3.6 Redirections |
1737 | ================ | |
ccc6cda3 | 1738 | |
37c41ab1 | 1739 | Before a command is executed, its input and output may be REDIRECTED |
ccc6cda3 JA |
1740 | using a special notation interpreted by the shell. Redirection may |
1741 | also be used to open and close files for the current shell execution | |
1742 | environment. The following redirection operators may precede or appear | |
1743 | anywhere within a simple command or may follow a command. Redirections | |
1744 | are processed in the order they appear, from left to right. | |
1745 | ||
1746 | In the following descriptions, if the file descriptor number is | |
1747 | omitted, and the first character of the redirection operator is `<', | |
1748 | the redirection refers to the standard input (file descriptor 0). If | |
1749 | the first character of the redirection operator is `>', the redirection | |
1750 | refers to the standard output (file descriptor 1). | |
1751 | ||
cce855bc JA |
1752 | The word following the redirection operator in the following |
1753 | descriptions, unless otherwise noted, is subjected to brace expansion, | |
1754 | tilde expansion, parameter expansion, command substitution, arithmetic | |
bb70624e JA |
1755 | expansion, quote removal, filename expansion, and word splitting. If |
1756 | it expands to more than one word, Bash reports an error. | |
ccc6cda3 JA |
1757 | |
1758 | Note that the order of redirections is significant. For example, | |
1759 | the command | |
1760 | ls > DIRLIST 2>&1 | |
37c41ab1 | 1761 | directs both standard output (file descriptor 1) and standard error |
bb70624e | 1762 | (file descriptor 2) to the file DIRLIST, while the command |
ccc6cda3 | 1763 | ls 2>&1 > DIRLIST |
37c41ab1 CR |
1764 | directs only the standard output to file DIRLIST, because the |
1765 | standard error was duplicated as standard output before the standard | |
1766 | output was redirected to DIRLIST. | |
ccc6cda3 | 1767 | |
bb70624e JA |
1768 | Bash handles several filenames specially when they are used in |
1769 | redirections, as described in the following table: | |
1770 | ||
1771 | `/dev/fd/FD' | |
1772 | If FD is a valid integer, file descriptor FD is duplicated. | |
1773 | ||
1774 | `/dev/stdin' | |
1775 | File descriptor 0 is duplicated. | |
1776 | ||
1777 | `/dev/stdout' | |
1778 | File descriptor 1 is duplicated. | |
1779 | ||
1780 | `/dev/stderr' | |
1781 | File descriptor 2 is duplicated. | |
1782 | ||
1783 | `/dev/tcp/HOST/PORT' | |
1784 | If HOST is a valid hostname or Internet address, and PORT is an | |
f73dda09 JA |
1785 | integer port number or service name, Bash attempts to open a TCP |
1786 | connection to the corresponding socket. | |
bb70624e JA |
1787 | |
1788 | `/dev/udp/HOST/PORT' | |
1789 | If HOST is a valid hostname or Internet address, and PORT is an | |
f73dda09 JA |
1790 | integer port number or service name, Bash attempts to open a UDP |
1791 | connection to the corresponding socket. | |
bb70624e | 1792 | |
761783bf | 1793 | |
cce855bc JA |
1794 | A failure to open or create a file causes the redirection to fail. |
1795 | ||
eb2bb562 CR |
1796 | Redirections using file descriptors greater than 9 should be used |
1797 | with care, as they may conflict with file descriptors the shell uses | |
1798 | internally. | |
1799 | ||
37c41ab1 CR |
1800 | 3.6.1 Redirecting Input |
1801 | ----------------------- | |
ccc6cda3 | 1802 | |
37c41ab1 | 1803 | Redirection of input causes the file whose name results from the |
ccc6cda3 JA |
1804 | expansion of WORD to be opened for reading on file descriptor `n', or |
1805 | the standard input (file descriptor 0) if `n' is not specified. | |
1806 | ||
1807 | The general format for redirecting input is: | |
7117c2d2 | 1808 | [N]<WORD |
ccc6cda3 | 1809 | |
37c41ab1 CR |
1810 | 3.6.2 Redirecting Output |
1811 | ------------------------ | |
ccc6cda3 | 1812 | |
37c41ab1 | 1813 | Redirection of output causes the file whose name results from the |
7117c2d2 JA |
1814 | expansion of WORD to be opened for writing on file descriptor N, or the |
1815 | standard output (file descriptor 1) if N is not specified. If the file | |
1816 | does not exist it is created; if it does exist it is truncated to zero | |
1817 | size. | |
ccc6cda3 JA |
1818 | |
1819 | The general format for redirecting output is: | |
7117c2d2 | 1820 | [N]>[|]WORD |
ccc6cda3 | 1821 | |
cce855bc JA |
1822 | If the redirection operator is `>', and the `noclobber' option to |
1823 | the `set' builtin has been enabled, the redirection will fail if the | |
bb70624e | 1824 | file whose name results from the expansion of WORD exists and is a |
cce855bc JA |
1825 | regular file. If the redirection operator is `>|', or the redirection |
1826 | operator is `>' and the `noclobber' option is not enabled, the | |
1827 | redirection is attempted even if the file named by WORD exists. | |
ccc6cda3 | 1828 | |
37c41ab1 CR |
1829 | 3.6.3 Appending Redirected Output |
1830 | --------------------------------- | |
ccc6cda3 | 1831 | |
37c41ab1 | 1832 | Redirection of output in this fashion causes the file whose name |
ccc6cda3 | 1833 | results from the expansion of WORD to be opened for appending on file |
7117c2d2 JA |
1834 | descriptor N, or the standard output (file descriptor 1) if N is not |
1835 | specified. If the file does not exist it is created. | |
ccc6cda3 JA |
1836 | |
1837 | The general format for appending output is: | |
7117c2d2 | 1838 | [N]>>WORD |
ccc6cda3 | 1839 | |
37c41ab1 CR |
1840 | 3.6.4 Redirecting Standard Output and Standard Error |
1841 | ---------------------------------------------------- | |
ccc6cda3 | 1842 | |
ed35cb4a CR |
1843 | This construct allows both the standard output (file descriptor 1) and |
1844 | the standard error output (file descriptor 2) to be redirected to the | |
1845 | file whose name is the expansion of WORD. | |
ccc6cda3 JA |
1846 | |
1847 | There are two formats for redirecting standard output and standard | |
1848 | error: | |
1849 | &>WORD | |
37c41ab1 | 1850 | and |
ccc6cda3 | 1851 | >&WORD |
37c41ab1 | 1852 | Of the two forms, the first is preferred. This is semantically |
ccc6cda3 JA |
1853 | equivalent to |
1854 | >WORD 2>&1 | |
1855 | ||
ed35cb4a CR |
1856 | 3.6.5 Appending Standard Output and Standard Error |
1857 | -------------------------------------------------- | |
1858 | ||
1859 | This construct allows both the standard output (file descriptor 1) and | |
1860 | the standard error output (file descriptor 2) to be appended to the | |
1861 | file whose name is the expansion of WORD. | |
1862 | ||
1863 | The format for appending standard output and standard error is: | |
1864 | &>>WORD | |
1865 | This is semantically equivalent to | |
1866 | >>WORD 2>&1 | |
1867 | ||
1868 | 3.6.6 Here Documents | |
37c41ab1 | 1869 | -------------------- |
ccc6cda3 | 1870 | |
37c41ab1 | 1871 | This type of redirection instructs the shell to read input from the |
ccc6cda3 JA |
1872 | current source until a line containing only WORD (with no trailing |
1873 | blanks) is seen. All of the lines read up to that point are then used | |
1874 | as the standard input for a command. | |
1875 | ||
7117c2d2 | 1876 | The format of here-documents is: |
ccc6cda3 JA |
1877 | <<[-]WORD |
1878 | HERE-DOCUMENT | |
1879 | DELIMITER | |
1880 | ||
bb70624e JA |
1881 | No parameter expansion, command substitution, arithmetic expansion, |
1882 | or filename expansion is performed on WORD. If any characters in WORD | |
ccc6cda3 | 1883 | are quoted, the DELIMITER is the result of quote removal on WORD, and |
cce855bc JA |
1884 | the lines in the here-document are not expanded. If WORD is unquoted, |
1885 | all lines of the here-document are subjected to parameter expansion, | |
1886 | command substitution, and arithmetic expansion. In the latter case, | |
bb70624e JA |
1887 | the character sequence `\newline' is ignored, and `\' must be used to |
1888 | quote the characters `\', `$', and ``'. | |
ccc6cda3 JA |
1889 | |
1890 | If the redirection operator is `<<-', then all leading tab | |
1891 | characters are stripped from input lines and the line containing | |
1892 | DELIMITER. This allows here-documents within shell scripts to be | |
1893 | indented in a natural fashion. | |
1894 | ||
ed35cb4a | 1895 | 3.6.7 Here Strings |
37c41ab1 | 1896 | ------------------ |
7117c2d2 | 1897 | |
37c41ab1 | 1898 | A variant of here documents, the format is: |
7117c2d2 JA |
1899 | <<< WORD |
1900 | ||
1901 | The WORD is expanded and supplied to the command on its standard | |
1902 | input. | |
1903 | ||
ed35cb4a | 1904 | 3.6.8 Duplicating File Descriptors |
37c41ab1 | 1905 | ---------------------------------- |
ccc6cda3 | 1906 | |
37c41ab1 | 1907 | The redirection operator |
7117c2d2 | 1908 | [N]<&WORD |
37c41ab1 CR |
1909 | is used to duplicate input file descriptors. If WORD expands to one |
1910 | or more digits, the file descriptor denoted by N is made to be a copy | |
1911 | of that file descriptor. If the digits in WORD do not specify a file | |
cce855bc | 1912 | descriptor open for input, a redirection error occurs. If WORD |
7117c2d2 JA |
1913 | evaluates to `-', file descriptor N is closed. If N is not specified, |
1914 | the standard input (file descriptor 0) is used. | |
ccc6cda3 JA |
1915 | |
1916 | The operator | |
7117c2d2 | 1917 | [N]>&WORD |
37c41ab1 | 1918 | is used similarly to duplicate output file descriptors. If N is not |
cce855bc JA |
1919 | specified, the standard output (file descriptor 1) is used. If the |
1920 | digits in WORD do not specify a file descriptor open for output, a | |
7117c2d2 JA |
1921 | redirection error occurs. As a special case, if N is omitted, and WORD |
1922 | does not expand to one or more digits, the standard output and standard | |
1923 | error are redirected as described previously. | |
1924 | ||
ed35cb4a | 1925 | 3.6.9 Moving File Descriptors |
37c41ab1 | 1926 | ----------------------------- |
7117c2d2 | 1927 | |
37c41ab1 | 1928 | The redirection operator |
7117c2d2 | 1929 | [N]<&DIGIT- |
37c41ab1 CR |
1930 | moves the file descriptor DIGIT to file descriptor N, or the |
1931 | standard input (file descriptor 0) if N is not specified. DIGIT is | |
1932 | closed after being duplicated to N. | |
7117c2d2 JA |
1933 | |
1934 | Similarly, the redirection operator | |
1935 | [N]>&DIGIT- | |
37c41ab1 CR |
1936 | moves the file descriptor DIGIT to file descriptor N, or the |
1937 | standard output (file descriptor 1) if N is not specified. | |
7117c2d2 | 1938 | |
ed35cb4a CR |
1939 | 3.6.10 Opening File Descriptors for Reading and Writing |
1940 | ------------------------------------------------------- | |
ccc6cda3 | 1941 | |
37c41ab1 | 1942 | The redirection operator |
7117c2d2 | 1943 | [N]<>WORD |
37c41ab1 | 1944 | causes the file whose name is the expansion of WORD to be opened for |
7117c2d2 JA |
1945 | both reading and writing on file descriptor N, or on file descriptor 0 |
1946 | if N is not specified. If the file does not exist, it is created. | |
ccc6cda3 JA |
1947 | |
1948 | \1f | |
1949 | File: bashref.info, Node: Executing Commands, Next: Shell Scripts, Prev: Redirections, Up: Basic Shell Features | |
1950 | ||
37c41ab1 CR |
1951 | 3.7 Executing Commands |
1952 | ====================== | |
ccc6cda3 JA |
1953 | |
1954 | * Menu: | |
1955 | ||
cce855bc JA |
1956 | * Simple Command Expansion:: How Bash expands simple commands before |
1957 | executing them. | |
ccc6cda3 | 1958 | * Command Search and Execution:: How Bash finds commands and runs them. |
cce855bc JA |
1959 | * Command Execution Environment:: The environment in which Bash |
1960 | executes commands that are not | |
1961 | shell builtins. | |
ccc6cda3 | 1962 | * Environment:: The environment given to a command. |
ccc6cda3 JA |
1963 | * Exit Status:: The status returned by commands and how Bash |
1964 | interprets it. | |
ccc6cda3 JA |
1965 | * Signals:: What happens when Bash or a command it runs |
1966 | receives a signal. | |
1967 | ||
1968 | \1f | |
cce855bc JA |
1969 | File: bashref.info, Node: Simple Command Expansion, Next: Command Search and Execution, Up: Executing Commands |
1970 | ||
37c41ab1 CR |
1971 | 3.7.1 Simple Command Expansion |
1972 | ------------------------------ | |
cce855bc | 1973 | |
37c41ab1 | 1974 | When a simple command is executed, the shell performs the following |
cce855bc JA |
1975 | expansions, assignments, and redirections, from left to right. |
1976 | ||
1977 | 1. The words that the parser has marked as variable assignments (those | |
1978 | preceding the command name) and redirections are saved for later | |
1979 | processing. | |
1980 | ||
1981 | 2. The words that are not variable assignments or redirections are | |
28ef6c31 | 1982 | expanded (*note Shell Expansions::). If any words remain after |
cce855bc JA |
1983 | expansion, the first word is taken to be the name of the command |
1984 | and the remaining words are the arguments. | |
1985 | ||
1986 | 3. Redirections are performed as described above (*note | |
28ef6c31 | 1987 | Redirections::). |
cce855bc JA |
1988 | |
1989 | 4. The text after the `=' in each variable assignment undergoes tilde | |
1990 | expansion, parameter expansion, command substitution, arithmetic | |
1991 | expansion, and quote removal before being assigned to the variable. | |
1992 | ||
1993 | If no command name results, the variable assignments affect the | |
1994 | current shell environment. Otherwise, the variables are added to the | |
1995 | environment of the executed command and do not affect the current shell | |
1996 | environment. If any of the assignments attempts to assign a value to a | |
1997 | readonly variable, an error occurs, and the command exits with a | |
1998 | non-zero status. | |
1999 | ||
2000 | If no command name results, redirections are performed, but do not | |
2001 | affect the current shell environment. A redirection error causes the | |
2002 | command to exit with a non-zero status. | |
2003 | ||
2004 | If there is a command name left after expansion, execution proceeds | |
2005 | as described below. Otherwise, the command exits. If one of the | |
2006 | expansions contained a command substitution, the exit status of the | |
2007 | command is the exit status of the last command substitution performed. | |
2008 | If there were no command substitutions, the command exits with a status | |
2009 | of zero. | |
2010 | ||
2011 | \1f | |
2012 | File: bashref.info, Node: Command Search and Execution, Next: Command Execution Environment, Prev: Simple Command Expansion, Up: Executing Commands | |
ccc6cda3 | 2013 | |
37c41ab1 CR |
2014 | 3.7.2 Command Search and Execution |
2015 | ---------------------------------- | |
ccc6cda3 | 2016 | |
37c41ab1 | 2017 | After a command has been split into words, if it results in a simple |
ccc6cda3 JA |
2018 | command and an optional list of arguments, the following actions are |
2019 | taken. | |
2020 | ||
2021 | 1. If the command name contains no slashes, the shell attempts to | |
2022 | locate it. If there exists a shell function by that name, that | |
6a8fd0ed | 2023 | function is invoked as described in *note Shell Functions::. |
ccc6cda3 JA |
2024 | |
2025 | 2. If the name does not match a function, the shell searches for it | |
2026 | in the list of shell builtins. If a match is found, that builtin | |
2027 | is invoked. | |
2028 | ||
2029 | 3. If the name is neither a shell function nor a builtin, and | |
2030 | contains no slashes, Bash searches each element of `$PATH' for a | |
2031 | directory containing an executable file by that name. Bash uses a | |
cce855bc JA |
2032 | hash table to remember the full pathnames of executable files to |
2033 | avoid multiple `PATH' searches (see the description of `hash' in | |
6a8fd0ed | 2034 | *note Bourne Shell Builtins::). A full search of the directories |
ccc6cda3 | 2035 | in `$PATH' is performed only if the command is not found in the |
ed35cb4a CR |
2036 | hash table. If the search is unsuccessful, the shell searches for |
2037 | a defined shell function named `command_not_found_handle'. If | |
2038 | that function exists, it is invoked with the original command and | |
2039 | the original command's arguments as its arguments, and the | |
2040 | function's exit status becomes the exit status of the shell. If | |
2041 | that function is not defined, the shell prints an error message | |
2042 | and returns an exit status of 127. | |
ccc6cda3 JA |
2043 | |
2044 | 4. If the search is successful, or if the command name contains one | |
cce855bc JA |
2045 | or more slashes, the shell executes the named program in a |
2046 | separate execution environment. Argument 0 is set to the name | |
2047 | given, and the remaining arguments to the command are set to the | |
2048 | arguments supplied, if any. | |
ccc6cda3 JA |
2049 | |
2050 | 5. If this execution fails because the file is not in executable | |
cce855bc | 2051 | format, and the file is not a directory, it is assumed to be a |
6a8fd0ed | 2052 | SHELL SCRIPT and the shell executes it as described in *note Shell |
cce855bc JA |
2053 | Scripts::. |
2054 | ||
2055 | 6. If the command was not begun asynchronously, the shell waits for | |
2056 | the command to complete and collects its exit status. | |
2057 | ||
2058 | ||
2059 | \1f | |
2060 | File: bashref.info, Node: Command Execution Environment, Next: Environment, Prev: Command Search and Execution, Up: Executing Commands | |
2061 | ||
37c41ab1 CR |
2062 | 3.7.3 Command Execution Environment |
2063 | ----------------------------------- | |
cce855bc | 2064 | |
37c41ab1 | 2065 | The shell has an EXECUTION ENVIRONMENT, which consists of the following: |
cce855bc JA |
2066 | |
2067 | * open files inherited by the shell at invocation, as modified by | |
2068 | redirections supplied to the `exec' builtin | |
2069 | ||
2070 | * the current working directory as set by `cd', `pushd', or `popd', | |
2071 | or inherited by the shell at invocation | |
2072 | ||
2073 | * the file creation mode mask as set by `umask' or inherited from | |
2074 | the shell's parent | |
2075 | ||
2076 | * current traps set by `trap' | |
2077 | ||
2078 | * shell parameters that are set by variable assignment or with `set' | |
2079 | or inherited from the shell's parent in the environment | |
2080 | ||
2081 | * shell functions defined during execution or inherited from the | |
2082 | shell's parent in the environment | |
2083 | ||
2084 | * options enabled at invocation (either by default or with | |
2085 | command-line arguments) or by `set' | |
2086 | ||
d3ad40de | 2087 | * options enabled by `shopt' (*note The Shopt Builtin::) |
cce855bc | 2088 | |
28ef6c31 | 2089 | * shell aliases defined with `alias' (*note Aliases::) |
cce855bc JA |
2090 | |
2091 | * various process IDs, including those of background jobs (*note | |
28ef6c31 JA |
2092 | Lists::), the value of `$$', and the value of `$PPID' |
2093 | ||
cce855bc JA |
2094 | |
2095 | When a simple command other than a builtin or shell function is to | |
2096 | be executed, it is invoked in a separate execution environment that | |
2097 | consists of the following. Unless otherwise noted, the values are | |
2098 | inherited from the shell. | |
2099 | ||
2100 | * the shell's open files, plus any modifications and additions | |
2101 | specified by redirections to the command | |
2102 | ||
2103 | * the current working directory | |
2104 | ||
2105 | * the file creation mode mask | |
2106 | ||
d3a24ed2 CR |
2107 | * shell variables and functions marked for export, along with |
2108 | variables exported for the command, passed in the environment | |
2109 | (*note Environment::) | |
cce855bc JA |
2110 | |
2111 | * traps caught by the shell are reset to the values inherited from | |
2112 | the shell's parent, and traps ignored by the shell are ignored | |
2113 | ||
28ef6c31 | 2114 | |
cce855bc JA |
2115 | A command invoked in this separate environment cannot affect the |
2116 | shell's execution environment. | |
2117 | ||
d3a24ed2 CR |
2118 | Command substitution, commands grouped with parentheses, and |
2119 | asynchronous commands are invoked in a subshell environment that is a | |
2120 | duplicate of the shell environment, except that traps caught by the | |
2121 | shell are reset to the values that the shell inherited from its parent | |
2122 | at invocation. Builtin commands that are invoked as part of a pipeline | |
2123 | are also executed in a subshell environment. Changes made to the | |
2124 | subshell environment cannot affect the shell's execution environment. | |
ccc6cda3 | 2125 | |
f73dda09 JA |
2126 | If a command is followed by a `&' and job control is not active, the |
2127 | default standard input for the command is the empty file `/dev/null'. | |
2128 | Otherwise, the invoked command inherits the file descriptors of the | |
2129 | calling shell as modified by redirections. | |
2130 | ||
ccc6cda3 | 2131 | \1f |
cce855bc | 2132 | File: bashref.info, Node: Environment, Next: Exit Status, Prev: Command Execution Environment, Up: Executing Commands |
ccc6cda3 | 2133 | |
37c41ab1 CR |
2134 | 3.7.4 Environment |
2135 | ----------------- | |
ccc6cda3 | 2136 | |
37c41ab1 | 2137 | When a program is invoked it is given an array of strings called the |
ccc6cda3 JA |
2138 | ENVIRONMENT. This is a list of name-value pairs, of the form |
2139 | `name=value'. | |
2140 | ||
bb70624e | 2141 | Bash provides several ways to manipulate the environment. On |
ccc6cda3 JA |
2142 | invocation, the shell scans its own environment and creates a parameter |
2143 | for each name found, automatically marking it for EXPORT to child | |
2144 | processes. Executed commands inherit the environment. The `export' | |
2145 | and `declare -x' commands allow parameters and functions to be added to | |
2146 | and deleted from the environment. If the value of a parameter in the | |
2147 | environment is modified, the new value becomes part of the environment, | |
2148 | replacing the old. The environment inherited by any executed command | |
2149 | consists of the shell's initial environment, whose values may be | |
cce855bc JA |
2150 | modified in the shell, less any pairs removed by the `unset' and |
2151 | `export -n' commands, plus any additions via the `export' and `declare | |
2152 | -x' commands. | |
ccc6cda3 JA |
2153 | |
2154 | The environment for any simple command or function may be augmented | |
2155 | temporarily by prefixing it with parameter assignments, as described in | |
6a8fd0ed | 2156 | *note Shell Parameters::. These assignment statements affect only the |
ccc6cda3 JA |
2157 | environment seen by that command. |
2158 | ||
28ef6c31 | 2159 | If the `-k' option is set (*note The Set Builtin::), then all |
ccc6cda3 JA |
2160 | parameter assignments are placed in the environment for a command, not |
2161 | just those that precede the command name. | |
2162 | ||
2163 | When Bash invokes an external command, the variable `$_' is set to | |
2164 | the full path name of the command and passed to that command in its | |
2165 | environment. | |
2166 | ||
2167 | \1f | |
2168 | File: bashref.info, Node: Exit Status, Next: Signals, Prev: Environment, Up: Executing Commands | |
2169 | ||
37c41ab1 CR |
2170 | 3.7.5 Exit Status |
2171 | ----------------- | |
ccc6cda3 | 2172 | |
29d25b54 CR |
2173 | The exit status of an executed command is the value returned by the |
2174 | WAITPID system call or equivalent function. Exit statuses fall between | |
2175 | 0 and 255, though, as explained below, the shell may use values above | |
2176 | 125 specially. Exit statuses from shell builtins and compound commands | |
2177 | are also limited to this range. Under certain circumstances, the shell | |
2178 | will use special values to indicate specific failure modes. | |
2179 | ||
2180 | For the shell's purposes, a command which exits with a zero exit | |
2181 | status has succeeded. A non-zero exit status indicates failure. This | |
cce855bc JA |
2182 | seemingly counter-intuitive scheme is used so there is one well-defined |
2183 | way to indicate success and a variety of ways to indicate various | |
2184 | failure modes. When a command terminates on a fatal signal whose | |
2185 | number is N, Bash uses the value 128+N as the exit status. | |
ccc6cda3 JA |
2186 | |
2187 | If a command is not found, the child process created to execute it | |
2188 | returns a status of 127. If a command is found but is not executable, | |
2189 | the return status is 126. | |
2190 | ||
cce855bc JA |
2191 | If a command fails because of an error during expansion or |
2192 | redirection, the exit status is greater than zero. | |
2193 | ||
ccc6cda3 | 2194 | The exit status is used by the Bash conditional commands (*note |
28ef6c31 JA |
2195 | Conditional Constructs::) and some of the list constructs (*note |
2196 | Lists::). | |
ccc6cda3 JA |
2197 | |
2198 | All of the Bash builtins return an exit status of zero if they | |
2199 | succeed and a non-zero status on failure, so they may be used by the | |
cce855bc JA |
2200 | conditional and list constructs. All builtins return an exit status of |
2201 | 2 to indicate incorrect usage. | |
ccc6cda3 JA |
2202 | |
2203 | \1f | |
2204 | File: bashref.info, Node: Signals, Prev: Exit Status, Up: Executing Commands | |
2205 | ||
37c41ab1 CR |
2206 | 3.7.6 Signals |
2207 | ------------- | |
ccc6cda3 | 2208 | |
37c41ab1 | 2209 | When Bash is interactive, in the absence of any traps, it ignores |
cce855bc JA |
2210 | `SIGTERM' (so that `kill 0' does not kill an interactive shell), and |
2211 | `SIGINT' is caught and handled (so that the `wait' builtin is | |
2212 | interruptible). When Bash receives a `SIGINT', it breaks out of any | |
2213 | executing loops. In all cases, Bash ignores `SIGQUIT'. If job control | |
28ef6c31 | 2214 | is in effect (*note Job Control::), Bash ignores `SIGTTIN', `SIGTTOU', |
cce855bc | 2215 | and `SIGTSTP'. |
ccc6cda3 | 2216 | |
5e13499c CR |
2217 | Non-builtin commands started by Bash have signal handlers set to the |
2218 | values inherited by the shell from its parent. When job control is not | |
2219 | in effect, asynchronous commands ignore `SIGINT' and `SIGQUIT' in | |
2220 | addition to these inherited handlers. Commands run as a result of | |
2221 | command substitution ignore the keyboard-generated job control signals | |
2222 | `SIGTTIN', `SIGTTOU', and `SIGTSTP'. | |
ccc6cda3 JA |
2223 | |
2224 | The shell exits by default upon receipt of a `SIGHUP'. Before | |
f73dda09 JA |
2225 | exiting, an interactive shell resends the `SIGHUP' to all jobs, running |
2226 | or stopped. Stopped jobs are sent `SIGCONT' to ensure that they receive | |
2227 | the `SIGHUP'. To prevent the shell from sending the `SIGHUP' signal to | |
2228 | a particular job, it should be removed from the jobs table with the | |
28ef6c31 | 2229 | `disown' builtin (*note Job Control Builtins::) or marked to not |
cce855bc JA |
2230 | receive `SIGHUP' using `disown -h'. |
2231 | ||
2232 | If the `huponexit' shell option has been set with `shopt' (*note | |
d3ad40de CR |
2233 | The Shopt Builtin::), Bash sends a `SIGHUP' to all jobs when an |
2234 | interactive login shell exits. | |
cce855bc | 2235 | |
5e13499c CR |
2236 | If Bash is waiting for a command to complete and receives a signal |
2237 | for which a trap has been set, the trap will not be executed until the | |
2238 | command completes. When Bash is waiting for an asynchronous command | |
2239 | via the `wait' builtin, the reception of a signal for which a trap has | |
2240 | been set will cause the `wait' builtin to return immediately with an | |
2241 | exit status greater than 128, immediately after which the trap is | |
2242 | executed. | |
ccc6cda3 JA |
2243 | |
2244 | \1f | |
2245 | File: bashref.info, Node: Shell Scripts, Prev: Executing Commands, Up: Basic Shell Features | |
2246 | ||
37c41ab1 CR |
2247 | 3.8 Shell Scripts |
2248 | ================= | |
ccc6cda3 | 2249 | |
37c41ab1 CR |
2250 | A shell script is a text file containing shell commands. When such a |
2251 | file is used as the first non-option argument when invoking Bash, and | |
28ef6c31 | 2252 | neither the `-c' nor `-s' option is supplied (*note Invoking Bash::), |
ccc6cda3 | 2253 | Bash reads and executes commands from the file, then exits. This mode |
f73dda09 JA |
2254 | of operation creates a non-interactive shell. The shell first searches |
2255 | for the file in the current directory, and looks in the directories in | |
2256 | `$PATH' if not found there. | |
2257 | ||
2258 | When Bash runs a shell script, it sets the special parameter `0' to | |
2259 | the name of the file, rather than the name of the shell, and the | |
2260 | positional parameters are set to the remaining arguments, if any are | |
2261 | given. If no additional arguments are supplied, the positional | |
2262 | parameters are unset. | |
ccc6cda3 JA |
2263 | |
2264 | A shell script may be made executable by using the `chmod' command | |
2265 | to turn on the execute bit. When Bash finds such a file while | |
2266 | searching the `$PATH' for a command, it spawns a subshell to execute | |
2267 | it. In other words, executing | |
2268 | filename ARGUMENTS | |
37c41ab1 | 2269 | is equivalent to executing |
ccc6cda3 JA |
2270 | bash filename ARGUMENTS |
2271 | ||
2272 | if `filename' is an executable shell script. This subshell | |
2273 | reinitializes itself, so that the effect is as if a new shell had been | |
cce855bc JA |
2274 | invoked to interpret the script, with the exception that the locations |
2275 | of commands remembered by the parent (see the description of `hash' in | |
6a8fd0ed | 2276 | *note Bourne Shell Builtins::) are retained by the child. |
ccc6cda3 | 2277 | |
bb70624e JA |
2278 | Most versions of Unix make this a part of the operating system's |
2279 | command execution mechanism. If the first line of a script begins with | |
2280 | the two characters `#!', the remainder of the line specifies an | |
2281 | interpreter for the program. Thus, you can specify Bash, `awk', Perl, | |
2282 | or some other interpreter and write the rest of the script file in that | |
2283 | language. | |
2284 | ||
2285 | The arguments to the interpreter consist of a single optional | |
2286 | argument following the interpreter name on the first line of the script | |
2287 | file, followed by the name of the script file, followed by the rest of | |
2288 | the arguments. Bash will perform this action on operating systems that | |
2289 | do not handle it themselves. Note that some older versions of Unix | |
2290 | limit the interpreter name and argument to a maximum of 32 characters. | |
2291 | ||
2292 | Bash scripts often begin with `#! /bin/bash' (assuming that Bash has | |
2293 | been installed in `/bin'), since this ensures that Bash will be used to | |
2294 | interpret the script, even if it is executed under another shell. | |
ccc6cda3 JA |
2295 | |
2296 | \1f | |
bb70624e | 2297 | File: bashref.info, Node: Shell Builtin Commands, Next: Shell Variables, Prev: Basic Shell Features, Up: Top |
ccc6cda3 | 2298 | |
37c41ab1 CR |
2299 | 4 Shell Builtin Commands |
2300 | ************************ | |
ccc6cda3 JA |
2301 | |
2302 | * Menu: | |
2303 | ||
2304 | * Bourne Shell Builtins:: Builtin commands inherited from the Bourne | |
2305 | Shell. | |
bb70624e | 2306 | * Bash Builtins:: Table of builtins specific to Bash. |
d3ad40de CR |
2307 | * Modifying Shell Behavior:: Builtins to modify shell attributes and |
2308 | optional behavior. | |
bb70624e | 2309 | * Special Builtins:: Builtin commands classified specially by |
ac18b312 | 2310 | POSIX. |
bb70624e JA |
2311 | |
2312 | Builtin commands are contained within the shell itself. When the | |
2313 | name of a builtin command is used as the first word of a simple command | |
28ef6c31 | 2314 | (*note Simple Commands::), the shell executes the command directly, |
bb70624e JA |
2315 | without invoking another program. Builtin commands are necessary to |
2316 | implement functionality impossible or inconvenient to obtain with | |
2317 | separate utilities. | |
ccc6cda3 | 2318 | |
ac18b312 CR |
2319 | This section briefly describes the builtins which Bash inherits from |
2320 | the Bourne Shell, as well as the builtin commands which are unique to | |
2321 | or have been extended in Bash. | |
bb70624e JA |
2322 | |
2323 | Several builtin commands are described in other chapters: builtin | |
2324 | commands which provide the Bash interface to the job control facilities | |
28ef6c31 JA |
2325 | (*note Job Control Builtins::), the directory stack (*note Directory |
2326 | Stack Builtins::), the command history (*note Bash History Builtins::), | |
2327 | and the programmable completion facilities (*note Programmable | |
2328 | Completion Builtins::). | |
bb70624e JA |
2329 | |
2330 | Many of the builtins have been extended by POSIX or Bash. | |
ccc6cda3 | 2331 | |
c2258e1c CR |
2332 | Unless otherwise noted, each builtin command documented as accepting |
2333 | options preceded by `-' accepts `--' to signify the end of the options. | |
1c72c0cd CR |
2334 | For example, the `:', `true', `false', and `test' builtins do not |
2335 | accept options. | |
c2258e1c | 2336 | |
ccc6cda3 | 2337 | \1f |
bb70624e | 2338 | File: bashref.info, Node: Bourne Shell Builtins, Next: Bash Builtins, Up: Shell Builtin Commands |
ccc6cda3 | 2339 | |
37c41ab1 CR |
2340 | 4.1 Bourne Shell Builtins |
2341 | ========================= | |
ccc6cda3 | 2342 | |
37c41ab1 | 2343 | The following shell builtin commands are inherited from the Bourne |
ac18b312 | 2344 | Shell. These commands are implemented as specified by the POSIX |
ccc6cda3 JA |
2345 | standard. |
2346 | ||
bb70624e | 2347 | `: (a colon)' |
ccc6cda3 JA |
2348 | : [ARGUMENTS] |
2349 | Do nothing beyond expanding ARGUMENTS and performing redirections. | |
cce855bc | 2350 | The return status is zero. |
ccc6cda3 | 2351 | |
bb70624e | 2352 | `. (a period)' |
b72432fd | 2353 | . FILENAME [ARGUMENTS] |
ccc6cda3 | 2354 | Read and execute commands from the FILENAME argument in the |
cce855bc | 2355 | current shell context. If FILENAME does not contain a slash, the |
28ef6c31 JA |
2356 | `PATH' variable is used to find FILENAME. When Bash is not in |
2357 | POSIX mode, the current directory is searched if FILENAME is not | |
2358 | found in `$PATH'. If any ARGUMENTS are supplied, they become the | |
2359 | positional parameters when FILENAME is executed. Otherwise the | |
2360 | positional parameters are unchanged. The return status is the | |
2361 | exit status of the last command executed, or zero if no commands | |
2362 | are executed. If FILENAME is not found, or cannot be read, the | |
2363 | return status is non-zero. This builtin is equivalent to `source'. | |
ccc6cda3 JA |
2364 | |
2365 | `break' | |
2366 | break [N] | |
2367 | Exit from a `for', `while', `until', or `select' loop. If N is | |
cce855bc JA |
2368 | supplied, the Nth enclosing loop is exited. N must be greater |
2369 | than or equal to 1. The return status is zero unless N is not | |
2370 | greater than or equal to 1. | |
ccc6cda3 JA |
2371 | |
2372 | `cd' | |
7117c2d2 | 2373 | cd [-L|-P] [DIRECTORY] |
ccc6cda3 JA |
2374 | Change the current working directory to DIRECTORY. If DIRECTORY |
2375 | is not given, the value of the `HOME' shell variable is used. If | |
2376 | the shell variable `CDPATH' exists, it is used as a search path. | |
d3a24ed2 CR |
2377 | If DIRECTORY begins with a slash, `CDPATH' is not used. |
2378 | ||
2379 | The `-P' option means to not follow symbolic links; symbolic links | |
2380 | are followed by default or with the `-L' option. If DIRECTORY is | |
2381 | `-', it is equivalent to `$OLDPWD'. | |
2382 | ||
2383 | If a non-empty directory name from `CDPATH' is used, or if `-' is | |
2384 | the first argument, and the directory change is successful, the | |
2385 | absolute pathname of the new working directory is written to the | |
2386 | standard output. | |
2387 | ||
2388 | The return status is zero if the directory is successfully changed, | |
2389 | non-zero otherwise. | |
ccc6cda3 JA |
2390 | |
2391 | `continue' | |
2392 | continue [N] | |
2393 | Resume the next iteration of an enclosing `for', `while', `until', | |
2394 | or `select' loop. If N is supplied, the execution of the Nth | |
cce855bc JA |
2395 | enclosing loop is resumed. N must be greater than or equal to 1. |
2396 | The return status is zero unless N is not greater than or equal to | |
2397 | 1. | |
ccc6cda3 JA |
2398 | |
2399 | `eval' | |
2400 | eval [ARGUMENTS] | |
2401 | The arguments are concatenated together into a single command, | |
cce855bc JA |
2402 | which is then read and executed, and its exit status returned as |
2403 | the exit status of `eval'. If there are no arguments or only | |
2404 | empty arguments, the return status is zero. | |
ccc6cda3 JA |
2405 | |
2406 | `exec' | |
cce855bc JA |
2407 | exec [-cl] [-a NAME] [COMMAND [ARGUMENTS]] |
2408 | If COMMAND is supplied, it replaces the shell without creating a | |
2409 | new process. If the `-l' option is supplied, the shell places a | |
d3ad40de CR |
2410 | dash at the beginning of the zeroth argument passed to COMMAND. |
2411 | This is what the `login' program does. The `-c' option causes | |
2412 | COMMAND to be executed with an empty environment. If `-a' is | |
2413 | supplied, the shell passes NAME as the zeroth argument to COMMAND. | |
2414 | If no COMMAND is specified, redirections may be used to affect the | |
cce855bc JA |
2415 | current shell environment. If there are no redirection errors, the |
2416 | return status is zero; otherwise the return status is non-zero. | |
ccc6cda3 JA |
2417 | |
2418 | `exit' | |
2419 | exit [N] | |
bb70624e JA |
2420 | Exit the shell, returning a status of N to the shell's parent. If |
2421 | N is omitted, the exit status is that of the last command executed. | |
cce855bc | 2422 | Any trap on `EXIT' is executed before the shell terminates. |
ccc6cda3 JA |
2423 | |
2424 | `export' | |
2425 | export [-fn] [-p] [NAME[=VALUE]] | |
2426 | Mark each NAME to be passed to child processes in the environment. | |
2427 | If the `-f' option is supplied, the NAMEs refer to shell | |
cce855bc JA |
2428 | functions; otherwise the names refer to shell variables. The `-n' |
2429 | option means to no longer mark each NAME for export. If no NAMES | |
2430 | are supplied, or if the `-p' option is given, a list of exported | |
2431 | names is displayed. The `-p' option displays output in a form | |
d3a24ed2 CR |
2432 | that may be reused as input. If a variable name is followed by |
2433 | =VALUE, the value of the variable is set to VALUE. | |
2434 | ||
2435 | The return status is zero unless an invalid option is supplied, | |
2436 | one of the names is not a valid shell variable name, or `-f' is | |
2437 | supplied with a name that is not a shell function. | |
ccc6cda3 JA |
2438 | |
2439 | `getopts' | |
2440 | getopts OPTSTRING NAME [ARGS] | |
2441 | `getopts' is used by shell scripts to parse positional parameters. | |
bb70624e JA |
2442 | OPTSTRING contains the option characters to be recognized; if a |
2443 | character is followed by a colon, the option is expected to have an | |
2444 | argument, which should be separated from it by white space. The | |
2445 | colon (`:') and question mark (`?') may not be used as option | |
2446 | characters. Each time it is invoked, `getopts' places the next | |
2447 | option in the shell variable NAME, initializing NAME if it does | |
2448 | not exist, and the index of the next argument to be processed into | |
2449 | the variable `OPTIND'. `OPTIND' is initialized to 1 each time the | |
2450 | shell or a shell script is invoked. When an option requires an | |
2451 | argument, `getopts' places that argument into the variable | |
2452 | `OPTARG'. The shell does not reset `OPTIND' automatically; it | |
2453 | must be manually reset between multiple calls to `getopts' within | |
2454 | the same shell invocation if a new set of parameters is to be used. | |
ccc6cda3 | 2455 | |
cce855bc JA |
2456 | When the end of options is encountered, `getopts' exits with a |
2457 | return value greater than zero. `OPTIND' is set to the index of | |
2458 | the first non-option argument, and `name' is set to `?'. | |
2459 | ||
2460 | `getopts' normally parses the positional parameters, but if more | |
2461 | arguments are given in ARGS, `getopts' parses those instead. | |
2462 | ||
ccc6cda3 JA |
2463 | `getopts' can report errors in two ways. If the first character of |
2464 | OPTSTRING is a colon, SILENT error reporting is used. In normal | |
cce855bc | 2465 | operation diagnostic messages are printed when invalid options or |
ccc6cda3 | 2466 | missing option arguments are encountered. If the variable `OPTERR' |
cce855bc | 2467 | is set to 0, no error messages will be displayed, even if the first |
ccc6cda3 JA |
2468 | character of `optstring' is not a colon. |
2469 | ||
cce855bc | 2470 | If an invalid option is seen, `getopts' places `?' into NAME and, |
ccc6cda3 JA |
2471 | if not silent, prints an error message and unsets `OPTARG'. If |
2472 | `getopts' is silent, the option character found is placed in | |
2473 | `OPTARG' and no diagnostic message is printed. | |
2474 | ||
2475 | If a required argument is not found, and `getopts' is not silent, | |
2476 | a question mark (`?') is placed in NAME, `OPTARG' is unset, and a | |
2477 | diagnostic message is printed. If `getopts' is silent, then a | |
2478 | colon (`:') is placed in NAME and `OPTARG' is set to the option | |
2479 | character found. | |
2480 | ||
ccc6cda3 | 2481 | `hash' |
ac18b312 | 2482 | hash [-r] [-p FILENAME] [-dt] [NAME] |
cce855bc JA |
2483 | Remember the full pathnames of commands specified as NAME |
2484 | arguments, so they need not be searched for on subsequent | |
2485 | invocations. The commands are found by searching through the | |
2486 | directories listed in `$PATH'. The `-p' option inhibits the path | |
2487 | search, and FILENAME is used as the location of NAME. The `-r' | |
7117c2d2 JA |
2488 | option causes the shell to forget all remembered locations. The |
2489 | `-d' option causes the shell to forget the remembered location of | |
2490 | each NAME. If the `-t' option is supplied, the full pathname to | |
2491 | which each NAME corresponds is printed. If multiple NAME | |
2492 | arguments are supplied with `-t' the NAME is printed before the | |
2493 | hashed full pathname. The `-l' option causes output to be | |
2494 | displayed in a format that may be reused as input. If no | |
2495 | arguments are given, or if only `-l' is supplied, information | |
2496 | about remembered commands is printed. The return status is zero | |
2497 | unless a NAME is not found or an invalid option is supplied. | |
ccc6cda3 JA |
2498 | |
2499 | `pwd' | |
2500 | pwd [-LP] | |
bb70624e JA |
2501 | Print the absolute pathname of the current working directory. If |
2502 | the `-P' option is supplied, the pathname printed will not contain | |
2503 | symbolic links. If the `-L' option is supplied, the pathname | |
2504 | printed may contain symbolic links. The return status is zero | |
2505 | unless an error is encountered while determining the name of the | |
2506 | current directory or an invalid option is supplied. | |
ccc6cda3 JA |
2507 | |
2508 | `readonly' | |
d3a24ed2 | 2509 | readonly [-apf] [NAME[=VALUE]] ... |
cce855bc JA |
2510 | Mark each NAME as readonly. The values of these names may not be |
2511 | changed by subsequent assignment. If the `-f' option is supplied, | |
2512 | each NAME refers to a shell function. The `-a' option means each | |
2513 | NAME refers to an array variable. If no NAME arguments are given, | |
2514 | or if the `-p' option is supplied, a list of all readonly names is | |
2515 | printed. The `-p' option causes output to be displayed in a | |
d3a24ed2 CR |
2516 | format that may be reused as input. If a variable name is |
2517 | followed by =VALUE, the value of the variable is set to VALUE. | |
2518 | The return status is zero unless an invalid option is supplied, | |
2519 | one of the NAME arguments is not a valid shell variable or | |
2520 | function name, or the `-f' option is supplied with a name that is | |
2521 | not a shell function. | |
ccc6cda3 JA |
2522 | |
2523 | `return' | |
2524 | return [N] | |
bb70624e JA |
2525 | Cause a shell function to exit with the return value N. If N is |
2526 | not supplied, the return value is the exit status of the last | |
2527 | command executed in the function. This may also be used to | |
2528 | terminate execution of a script being executed with the `.' (or | |
2529 | `source') builtin, returning either N or the exit status of the | |
cce855bc | 2530 | last command executed within the script as the exit status of the |
d3a24ed2 CR |
2531 | script. Any command associated with the `RETURN' trap is executed |
2532 | before execution resumes after the function or script. The return | |
2533 | status is non-zero if `return' is used outside a function and not | |
2534 | during the execution of a script by `.' or `source'. | |
ccc6cda3 JA |
2535 | |
2536 | `shift' | |
2537 | shift [N] | |
cce855bc | 2538 | Shift the positional parameters to the left by N. The positional |
d3ad40de CR |
2539 | parameters from N+1 ... `$#' are renamed to `$1' ... `$#'-N. |
2540 | Parameters represented by the numbers `$#' to `$#'-N+1 are unset. | |
2541 | N must be a non-negative number less than or equal to `$#'. If N | |
2542 | is zero or greater than `$#', the positional parameters are not | |
bb70624e JA |
2543 | changed. If N is not supplied, it is assumed to be 1. The return |
2544 | status is zero unless N is greater than `$#' or less than zero, | |
2545 | non-zero otherwise. | |
ccc6cda3 JA |
2546 | |
2547 | `test' | |
2548 | `[' | |
cce855bc JA |
2549 | Evaluate a conditional expression EXPR. Each operator and operand |
2550 | must be a separate argument. Expressions are composed of the | |
6a8fd0ed | 2551 | primaries described below in *note Bash Conditional Expressions::. |
1c72c0cd CR |
2552 | `test' does not accept any options, nor does it accept and ignore |
2553 | an argument of `--' as signifying the end of options. | |
cce855bc | 2554 | |
bb70624e JA |
2555 | When the `[' form is used, the last argument to the command must |
2556 | be a `]'. | |
2557 | ||
cce855bc | 2558 | Expressions may be combined using the following operators, listed |
d7f49990 CR |
2559 | in decreasing order of precedence. The evaluation depends on the |
2560 | number of arguments; see below. | |
cce855bc JA |
2561 | |
2562 | `! EXPR' | |
2563 | True if EXPR is false. | |
2564 | ||
2565 | `( EXPR )' | |
2566 | Returns the value of EXPR. This may be used to override the | |
2567 | normal precedence of operators. | |
2568 | ||
2569 | `EXPR1 -a EXPR2' | |
2570 | True if both EXPR1 and EXPR2 are true. | |
2571 | ||
2572 | `EXPR1 -o EXPR2' | |
2573 | True if either EXPR1 or EXPR2 is true. | |
2574 | ||
2575 | The `test' and `[' builtins evaluate conditional expressions using | |
2576 | a set of rules based on the number of arguments. | |
2577 | ||
2578 | 0 arguments | |
2579 | The expression is false. | |
2580 | ||
2581 | 1 argument | |
2582 | The expression is true if and only if the argument is not | |
2583 | null. | |
2584 | ||
2585 | 2 arguments | |
2586 | If the first argument is `!', the expression is true if and | |
2587 | only if the second argument is null. If the first argument | |
2588 | is one of the unary conditional operators (*note Bash | |
28ef6c31 | 2589 | Conditional Expressions::), the expression is true if the |
cce855bc JA |
2590 | unary test is true. If the first argument is not a valid |
2591 | unary operator, the expression is false. | |
2592 | ||
2593 | 3 arguments | |
2594 | If the second argument is one of the binary conditional | |
28ef6c31 | 2595 | operators (*note Bash Conditional Expressions::), the result |
cce855bc | 2596 | of the expression is the result of the binary test using the |
d7f49990 CR |
2597 | first and third arguments as operands. The `-a' and `-o' |
2598 | operators are considered binary operators when there are | |
2599 | three arguments. If the first argument is `!', the value is | |
2600 | the negation of the two-argument test using the second and | |
2601 | third arguments. If the first argument is exactly `(' and | |
2602 | the third argument is exactly `)', the result is the | |
2603 | one-argument test of the second argument. Otherwise, the | |
2604 | expression is false. | |
cce855bc JA |
2605 | |
2606 | 4 arguments | |
2607 | If the first argument is `!', the result is the negation of | |
2608 | the three-argument expression composed of the remaining | |
2609 | arguments. Otherwise, the expression is parsed and evaluated | |
2610 | according to precedence using the rules listed above. | |
2611 | ||
2612 | 5 or more arguments | |
2613 | The expression is parsed and evaluated according to precedence | |
2614 | using the rules listed above. | |
ccc6cda3 JA |
2615 | |
2616 | `times' | |
2617 | times | |
2618 | Print out the user and system times used by the shell and its | |
cce855bc | 2619 | children. The return status is zero. |
ccc6cda3 JA |
2620 | |
2621 | `trap' | |
d166f048 | 2622 | trap [-lp] [ARG] [SIGSPEC ...] |
ccc6cda3 | 2623 | The commands in ARG are to be read and executed when the shell |
9f422431 CR |
2624 | receives signal SIGSPEC. If ARG is absent (and there is a single |
2625 | SIGSPEC) or equal to `-', each specified signal's disposition is | |
2626 | reset to the value it had when the shell was started. If ARG is | |
2627 | the null string, then the signal specified by each SIGSPEC is | |
2628 | ignored by the shell and commands it invokes. If ARG is not | |
2629 | present and `-p' has been supplied, the shell displays the trap | |
2630 | commands associated with each SIGSPEC. If no arguments are | |
2631 | supplied, or only `-p' is given, `trap' prints the list of commands | |
2632 | associated with each signal number in a form that may be reused as | |
2633 | shell input. The `-l' option causes the shell to print a list of | |
2634 | signal names and their corresponding numbers. Each SIGSPEC is | |
2635 | either a signal name or a signal number. Signal names are case | |
2636 | insensitive and the `SIG' prefix is optional. If a SIGSPEC is `0' | |
d3a24ed2 CR |
2637 | or `EXIT', ARG is executed when the shell exits. If a SIGSPEC is |
2638 | `DEBUG', the command ARG is executed before every simple command, | |
2639 | `for' command, `case' command, `select' command, every arithmetic | |
2640 | `for' command, and before the first command executes in a shell | |
2641 | function. Refer to the description of the `extglob' option to the | |
d3ad40de CR |
2642 | `shopt' builtin (*note The Shopt Builtin::) for details of its |
2643 | effect on the `DEBUG' trap. If a SIGSPEC is `ERR', the command ARG | |
2644 | is executed whenever a simple command has a non-zero exit status, | |
5e13499c CR |
2645 | subject to the following conditions. The `ERR' trap is not |
2646 | executed if the failed command is part of the command list | |
2647 | immediately following an `until' or `while' keyword, part of the | |
c2a47ea9 CR |
2648 | test in an `if' statement, part of a command executed in a `&&' or |
2649 | `||' list, or if the command's return status is being inverted | |
2650 | using `!'. These are the same conditions obeyed by the `errexit' | |
2651 | option. If a SIGSPEC is `RETURN', the command ARG is executed | |
2652 | each time a shell function or a script executed with the `.' or | |
2653 | `source' builtins finishes executing. | |
d3a24ed2 | 2654 | |
ccc6cda3 | 2655 | Signals ignored upon entry to the shell cannot be trapped or reset. |
d3ad40de CR |
2656 | Trapped signals that are not being ignored are reset to their |
2657 | original values in a child process when it is created. | |
ccc6cda3 | 2658 | |
cce855bc JA |
2659 | The return status is zero unless a SIGSPEC does not specify a |
2660 | valid signal. | |
2661 | ||
ccc6cda3 | 2662 | `umask' |
cce855bc | 2663 | umask [-p] [-S] [MODE] |
ccc6cda3 JA |
2664 | Set the shell process's file creation mask to MODE. If MODE |
2665 | begins with a digit, it is interpreted as an octal number; if not, | |
2666 | it is interpreted as a symbolic mode mask similar to that accepted | |
2667 | by the `chmod' command. If MODE is omitted, the current value of | |
2668 | the mask is printed. If the `-S' option is supplied without a | |
cce855bc JA |
2669 | MODE argument, the mask is printed in a symbolic format. If the |
2670 | `-p' option is supplied, and MODE is omitted, the output is in a | |
2671 | form that may be reused as input. The return status is zero if | |
2672 | the mode is successfully changed or if no MODE argument is | |
2673 | supplied, and non-zero otherwise. | |
ccc6cda3 | 2674 | |
bb70624e JA |
2675 | Note that when the mode is interpreted as an octal number, each |
2676 | number of the umask is subtracted from `7'. Thus, a umask of `022' | |
2677 | results in permissions of `755'. | |
2678 | ||
ccc6cda3 JA |
2679 | `unset' |
2680 | unset [-fv] [NAME] | |
2681 | Each variable or function NAME is removed. If no options are | |
2682 | supplied, or the `-v' option is given, each NAME refers to a shell | |
2683 | variable. If the `-f' option is given, the NAMEs refer to shell | |
cce855bc JA |
2684 | functions, and the function definition is removed. Readonly |
2685 | variables and functions may not be unset. The return status is | |
d3a24ed2 | 2686 | zero unless a NAME is readonly. |
ccc6cda3 JA |
2687 | |
2688 | \1f | |
d3ad40de | 2689 | File: bashref.info, Node: Bash Builtins, Next: Modifying Shell Behavior, Prev: Bourne Shell Builtins, Up: Shell Builtin Commands |
ccc6cda3 | 2690 | |
37c41ab1 CR |
2691 | 4.2 Bash Builtin Commands |
2692 | ========================= | |
ccc6cda3 | 2693 | |
37c41ab1 | 2694 | This section describes builtin commands which are unique to or have |
bb70624e | 2695 | been extended in Bash. Some of these commands are specified in the |
ac18b312 | 2696 | POSIX standard. |
ccc6cda3 | 2697 | |
bb70624e JA |
2698 | `alias' |
2699 | alias [`-p'] [NAME[=VALUE] ...] | |
ccc6cda3 | 2700 | |
bb70624e JA |
2701 | Without arguments or with the `-p' option, `alias' prints the list |
2702 | of aliases on the standard output in a form that allows them to be | |
2703 | reused as input. If arguments are supplied, an alias is defined | |
2704 | for each NAME whose VALUE is given. If no VALUE is given, the name | |
6a8fd0ed | 2705 | and value of the alias is printed. Aliases are described in *note |
bb70624e | 2706 | Aliases::. |
ccc6cda3 | 2707 | |
bb70624e JA |
2708 | `bind' |
2709 | bind [-m KEYMAP] [-lpsvPSV] | |
2710 | bind [-m KEYMAP] [-q FUNCTION] [-u FUNCTION] [-r KEYSEQ] | |
2711 | bind [-m KEYMAP] -f FILENAME | |
2712 | bind [-m KEYMAP] -x KEYSEQ:SHELL-COMMAND | |
2713 | bind [-m KEYMAP] KEYSEQ:FUNCTION-NAME | |
7117c2d2 | 2714 | bind READLINE-COMMAND |
ccc6cda3 | 2715 | |
28ef6c31 | 2716 | Display current Readline (*note Command Line Editing::) key and |
7117c2d2 JA |
2717 | function bindings, bind a key sequence to a Readline function or |
2718 | macro, or set a Readline variable. Each non-option argument is a | |
d3ad40de | 2719 | command as it would appear in a Readline initialization file |
7117c2d2 JA |
2720 | (*note Readline Init File::), but each binding or command must be |
2721 | passed as a separate argument; e.g., | |
ed35cb4a CR |
2722 | `"\C-x\C-r":re-read-init-file'. |
2723 | ||
2724 | Options, if supplied, have the following meanings: | |
ccc6cda3 | 2725 | |
bb70624e JA |
2726 | `-m KEYMAP' |
2727 | Use KEYMAP as the keymap to be affected by the subsequent | |
2728 | bindings. Acceptable KEYMAP names are `emacs', | |
28ef6c31 | 2729 | `emacs-standard', `emacs-meta', `emacs-ctlx', `vi', `vi-move', |
bb70624e JA |
2730 | `vi-command', and `vi-insert'. `vi' is equivalent to |
2731 | `vi-command'; `emacs' is equivalent to `emacs-standard'. | |
cce855bc | 2732 | |
bb70624e JA |
2733 | `-l' |
2734 | List the names of all Readline functions. | |
cce855bc | 2735 | |
bb70624e JA |
2736 | `-p' |
2737 | Display Readline function names and bindings in such a way | |
2738 | that they can be used as input or in a Readline | |
2739 | initialization file. | |
cce855bc | 2740 | |
bb70624e JA |
2741 | `-P' |
2742 | List current Readline function names and bindings. | |
cce855bc | 2743 | |
bb70624e JA |
2744 | `-v' |
2745 | Display Readline variable names and values in such a way that | |
2746 | they can be used as input or in a Readline initialization | |
2747 | file. | |
ccc6cda3 | 2748 | |
bb70624e JA |
2749 | `-V' |
2750 | List current Readline variable names and values. | |
ccc6cda3 | 2751 | |
bb70624e JA |
2752 | `-s' |
2753 | Display Readline key sequences bound to macros and the | |
2754 | strings they output in such a way that they can be used as | |
2755 | input or in a Readline initialization file. | |
ccc6cda3 | 2756 | |
bb70624e JA |
2757 | `-S' |
2758 | Display Readline key sequences bound to macros and the | |
2759 | strings they output. | |
ccc6cda3 | 2760 | |
bb70624e JA |
2761 | `-f FILENAME' |
2762 | Read key bindings from FILENAME. | |
ccc6cda3 | 2763 | |
bb70624e JA |
2764 | `-q FUNCTION' |
2765 | Query about which keys invoke the named FUNCTION. | |
ccc6cda3 | 2766 | |
bb70624e JA |
2767 | `-u FUNCTION' |
2768 | Unbind all keys bound to the named FUNCTION. | |
ccc6cda3 | 2769 | |
bb70624e JA |
2770 | `-r KEYSEQ' |
2771 | Remove any current binding for KEYSEQ. | |
ccc6cda3 | 2772 | |
bb70624e JA |
2773 | `-x KEYSEQ:SHELL-COMMAND' |
2774 | Cause SHELL-COMMAND to be executed whenever KEYSEQ is entered. | |
ed35cb4a CR |
2775 | When SHELL-COMMAND is executed, the shell sets the |
2776 | `READLINE_LINE' variable to the contents of the Readline line | |
2777 | buffer and the `READLINE_POINT' variable to the current | |
2778 | location of the insertion point. If the executed command | |
2779 | changes the value of `READLINE_LINE' or `READLINE_POINT', | |
2780 | those new values will be reflected in the editing state. | |
761783bf | 2781 | |
bb70624e JA |
2782 | The return status is zero unless an invalid option is supplied or |
2783 | an error occurs. | |
ccc6cda3 | 2784 | |
bb70624e JA |
2785 | `builtin' |
2786 | builtin [SHELL-BUILTIN [ARGS]] | |
2787 | Run a shell builtin, passing it ARGS, and return its exit status. | |
2788 | This is useful when defining a shell function with the same name | |
2789 | as a shell builtin, retaining the functionality of the builtin | |
2790 | within the function. The return status is non-zero if | |
2791 | SHELL-BUILTIN is not a shell builtin command. | |
ccc6cda3 | 2792 | |
d3a24ed2 CR |
2793 | `caller' |
2794 | caller [EXPR] | |
2795 | Returns the context of any active subroutine call (a shell | |
5e13499c | 2796 | function or a script executed with the `.' or `source' builtins). |
d3a24ed2 CR |
2797 | |
2798 | Without EXPR, `caller' displays the line number and source | |
2799 | filename of the current subroutine call. If a non-negative | |
2800 | integer is supplied as EXPR, `caller' displays the line number, | |
2801 | subroutine name, and source file corresponding to that position in | |
2802 | the current execution call stack. This extra information may be | |
2803 | used, for example, to print a stack trace. The current frame is | |
2804 | frame 0. | |
2805 | ||
2806 | The return value is 0 unless the shell is not executing a | |
2807 | subroutine call or EXPR does not correspond to a valid position in | |
2808 | the call stack. | |
2809 | ||
bb70624e JA |
2810 | `command' |
2811 | command [-pVv] COMMAND [ARGUMENTS ...] | |
2812 | Runs COMMAND with ARGUMENTS ignoring any shell function named | |
2813 | COMMAND. Only shell builtin commands or commands found by | |
2814 | searching the `PATH' are executed. If there is a shell function | |
2815 | named `ls', running `command ls' within the function will execute | |
2816 | the external command `ls' instead of calling the function | |
2817 | recursively. The `-p' option means to use a default value for | |
28ef6c31 | 2818 | `PATH' that is guaranteed to find all of the standard utilities. |
bb70624e JA |
2819 | The return status in this case is 127 if COMMAND cannot be found |
2820 | or an error occurred, and the exit status of COMMAND otherwise. | |
ccc6cda3 | 2821 | |
bb70624e JA |
2822 | If either the `-V' or `-v' option is supplied, a description of |
2823 | COMMAND is printed. The `-v' option causes a single word | |
2824 | indicating the command or file name used to invoke COMMAND to be | |
2825 | displayed; the `-V' option produces a more verbose description. | |
2826 | In this case, the return status is zero if COMMAND is found, and | |
2827 | non-zero if not. | |
ccc6cda3 | 2828 | |
bb70624e | 2829 | `declare' |
d3a24ed2 | 2830 | declare [-afFirtx] [-p] [NAME[=VALUE] ...] |
ccc6cda3 | 2831 | |
bb70624e JA |
2832 | Declare variables and give them attributes. If no NAMEs are |
2833 | given, then display the values of variables instead. | |
ccc6cda3 | 2834 | |
bb70624e | 2835 | The `-p' option will display the attributes and values of each |
6a8fd0ed CR |
2836 | NAME. When `-p' is used with NAME arguments, additional options |
2837 | are ignored. | |
2838 | ||
2839 | When `-p' is supplied without NAME arguments, `declare' will | |
2840 | display the attributes and values of all variables having the | |
2841 | attributes specified by the additional options. If no other | |
2842 | options are supplied with `-p', `declare' will display the | |
2843 | attributes and values of all shell variables. The `-f' option | |
2844 | will restrict the display to shell functions. | |
2845 | ||
2846 | The `-F' option inhibits the display of function definitions; only | |
2847 | the function name and attributes are printed. If the `extdebug' | |
2848 | shell option is enabled using `shopt' (*note The Shopt Builtin::), | |
2849 | the source file name and line number where the function is defined | |
2850 | are displayed as well. `-F' implies `-f'. The following options | |
2851 | can be used to restrict output to variables with the specified | |
d3a24ed2 | 2852 | attributes or to give variables attributes: |
ccc6cda3 | 2853 | |
bb70624e | 2854 | `-a' |
28ef6c31 | 2855 | Each NAME is an array variable (*note Arrays::). |
ccc6cda3 | 2856 | |
bb70624e JA |
2857 | `-f' |
2858 | Use function names only. | |
ccc6cda3 | 2859 | |
bb70624e JA |
2860 | `-i' |
2861 | The variable is to be treated as an integer; arithmetic | |
28ef6c31 | 2862 | evaluation (*note Shell Arithmetic::) is performed when the |
bb70624e | 2863 | variable is assigned a value. |
ccc6cda3 | 2864 | |
bb70624e JA |
2865 | `-r' |
2866 | Make NAMEs readonly. These names cannot then be assigned | |
2867 | values by subsequent assignment statements or unset. | |
ccc6cda3 | 2868 | |
7117c2d2 JA |
2869 | `-t' |
2870 | Give each NAME the `trace' attribute. Traced functions | |
8fed3589 CR |
2871 | inherit the `DEBUG' and `RETURN' traps from the calling shell. |
2872 | The trace attribute has no special meaning for variables. | |
7117c2d2 | 2873 | |
bb70624e JA |
2874 | `-x' |
2875 | Mark each NAME for export to subsequent commands via the | |
2876 | environment. | |
ccc6cda3 | 2877 | |
d3ad40de CR |
2878 | Using `+' instead of `-' turns off the attribute instead, with the |
2879 | exceptions that `+a' may not be used to destroy an array variable | |
2880 | and `+r' will not remove the readonly attribute. When used in a | |
2881 | function, `declare' makes each NAME local, as with the `local' | |
2882 | command. If a variable name is followed by =VALUE, the value of | |
2883 | the variable is set to VALUE. | |
ccc6cda3 | 2884 | |
bb70624e JA |
2885 | The return status is zero unless an invalid option is encountered, |
2886 | an attempt is made to define a function using `-f foo=bar', an | |
2887 | attempt is made to assign a value to a readonly variable, an | |
2888 | attempt is made to assign a value to an array variable without | |
28ef6c31 | 2889 | using the compound assignment syntax (*note Arrays::), one of the |
bb70624e JA |
2890 | NAMES is not a valid shell variable name, an attempt is made to |
2891 | turn off readonly status for a readonly variable, an attempt is | |
2892 | made to turn off array status for an array variable, or an attempt | |
2893 | is made to display a non-existent function with `-f'. | |
ccc6cda3 | 2894 | |
bb70624e JA |
2895 | `echo' |
2896 | echo [-neE] [ARG ...] | |
2897 | Output the ARGs, separated by spaces, terminated with a newline. | |
2898 | The return status is always 0. If `-n' is specified, the trailing | |
2899 | newline is suppressed. If the `-e' option is given, | |
2900 | interpretation of the following backslash-escaped characters is | |
2901 | enabled. The `-E' option disables the interpretation of these | |
2902 | escape characters, even on systems where they are interpreted by | |
2903 | default. The `xpg_echo' shell option may be used to dynamically | |
2904 | determine whether or not `echo' expands these escape characters by | |
1c72c0cd CR |
2905 | default. `echo' does not interpret `--' to mean the end of |
2906 | options. | |
2907 | ||
2908 | `echo' interprets the following escape sequences: | |
bb70624e JA |
2909 | `\a' |
2910 | alert (bell) | |
ccc6cda3 | 2911 | |
bb70624e JA |
2912 | `\b' |
2913 | backspace | |
ccc6cda3 | 2914 | |
bb70624e JA |
2915 | `\c' |
2916 | suppress trailing newline | |
ccc6cda3 | 2917 | |
bb70624e JA |
2918 | `\e' |
2919 | escape | |
ccc6cda3 | 2920 | |
bb70624e JA |
2921 | `\f' |
2922 | form feed | |
ccc6cda3 | 2923 | |
bb70624e JA |
2924 | `\n' |
2925 | new line | |
ccc6cda3 | 2926 | |
bb70624e JA |
2927 | `\r' |
2928 | carriage return | |
ccc6cda3 | 2929 | |
bb70624e JA |
2930 | `\t' |
2931 | horizontal tab | |
ccc6cda3 | 2932 | |
bb70624e JA |
2933 | `\v' |
2934 | vertical tab | |
ccc6cda3 | 2935 | |
bb70624e JA |
2936 | `\\' |
2937 | backslash | |
ccc6cda3 | 2938 | |
7117c2d2 JA |
2939 | `\0NNN' |
2940 | the eight-bit character whose value is the octal value NNN | |
2941 | (zero to three octal digits) | |
2942 | ||
f73dda09 JA |
2943 | `\xHH' |
2944 | the eight-bit character whose value is the hexadecimal value | |
2945 | HH (one or two hex digits) | |
2946 | ||
bb70624e | 2947 | `enable' |
d3ad40de | 2948 | enable [-a] [-dnps] [-f FILENAME] [NAME ...] |
bb70624e JA |
2949 | Enable and disable builtin shell commands. Disabling a builtin |
2950 | allows a disk command which has the same name as a shell builtin | |
2951 | to be executed without specifying a full pathname, even though the | |
2952 | shell normally searches for builtins before disk commands. If | |
2953 | `-n' is used, the NAMEs become disabled. Otherwise NAMEs are | |
2954 | enabled. For example, to use the `test' binary found via `$PATH' | |
2955 | instead of the shell builtin version, type `enable -n test'. | |
ccc6cda3 | 2956 | |
bb70624e JA |
2957 | If the `-p' option is supplied, or no NAME arguments appear, a |
2958 | list of shell builtins is printed. With no other arguments, the | |
2959 | list consists of all enabled shell builtins. The `-a' option | |
2960 | means to list each builtin with an indication of whether or not it | |
2961 | is enabled. | |
ccc6cda3 | 2962 | |
bb70624e JA |
2963 | The `-f' option means to load the new builtin command NAME from |
2964 | shared object FILENAME, on systems that support dynamic loading. | |
2965 | The `-d' option will delete a builtin loaded with `-f'. | |
ccc6cda3 | 2966 | |
bb70624e JA |
2967 | If there are no options, a list of the shell builtins is displayed. |
2968 | The `-s' option restricts `enable' to the POSIX special builtins. | |
2969 | If `-s' is used with `-f', the new builtin becomes a special | |
28ef6c31 | 2970 | builtin (*note Special Builtins::). |
ccc6cda3 | 2971 | |
bb70624e JA |
2972 | The return status is zero unless a NAME is not a shell builtin or |
2973 | there is an error loading a new builtin from a shared object. | |
ccc6cda3 | 2974 | |
bb70624e | 2975 | `help' |
ed35cb4a | 2976 | help [-dms] [PATTERN] |
bb70624e JA |
2977 | Display helpful information about builtin commands. If PATTERN is |
2978 | specified, `help' gives detailed help on all commands matching | |
ed35cb4a CR |
2979 | PATTERN, otherwise a list of the builtins is printed. |
2980 | ||
2981 | Options, if supplied, have the following meanings: | |
2982 | ||
2983 | `-d' | |
2984 | Display a short description of each PATTERN | |
2985 | ||
2986 | `-m' | |
2987 | Display the description of each PATTERN in a manpage-like | |
2988 | format | |
2989 | ||
2990 | `-s' | |
2991 | Display only a short usage synopsis for each PATTERN | |
2992 | ||
2993 | The return status is zero unless no command matches PATTERN. | |
ccc6cda3 | 2994 | |
bb70624e JA |
2995 | `let' |
2996 | let EXPRESSION [EXPRESSION] | |
2997 | The `let' builtin allows arithmetic to be performed on shell | |
2998 | variables. Each EXPRESSION is evaluated according to the rules | |
6a8fd0ed | 2999 | given below in *note Shell Arithmetic::. If the last EXPRESSION |
bb70624e | 3000 | evaluates to 0, `let' returns 1; otherwise 0 is returned. |
ccc6cda3 | 3001 | |
bb70624e | 3002 | `local' |
d3a24ed2 | 3003 | local [OPTION] NAME[=VALUE] ... |
bb70624e JA |
3004 | For each argument, a local variable named NAME is created, and |
3005 | assigned VALUE. The OPTION can be any of the options accepted by | |
3006 | `declare'. `local' can only be used within a function; it makes | |
3007 | the variable NAME have a visible scope restricted to that function | |
3008 | and its children. The return status is zero unless `local' is | |
3009 | used outside a function, an invalid NAME is supplied, or NAME is a | |
3010 | readonly variable. | |
ccc6cda3 | 3011 | |
bb70624e JA |
3012 | `logout' |
3013 | logout [N] | |
3014 | Exit a login shell, returning a status of N to the shell's parent. | |
ccc6cda3 | 3015 | |
ed35cb4a CR |
3016 | `mapfile' |
3017 | mapfile [-n COUNT] [-O ORIGIN] [-s COUNT] [-t] [-u FD] [ | |
3018 | -C CALLBACK] [-c QUANTUM] [ARRAY] | |
3019 | Read lines from the standard input into array variable ARRAY, or | |
3020 | from file descriptor FD if the `-u' option is supplied. The | |
3021 | variable `MAPFILE' is the default ARRAY. Options, if supplied, | |
3022 | have the following meanings: | |
3023 | `-n' | |
3024 | Copy at most COUNT lines. If COUNT is 0, all lines are | |
3025 | copied. | |
3026 | ||
3027 | `-O' | |
3028 | Begin assigning to ARRAY at index ORIGIN. The default index | |
3029 | is 0. | |
3030 | ||
3031 | `-s' | |
3032 | Discard the first COUNT lines read. | |
3033 | ||
3034 | `-t' | |
3035 | Remove a trailing line from each line read. | |
3036 | ||
3037 | `-u' | |
3038 | Read lines from file descriptor FD instead of the standard | |
3039 | input. | |
3040 | ||
3041 | `-C' | |
3042 | Evaluate CALLBACK each time QUANTUMP lines are read. The | |
3043 | `-c' option specifies QUANTUM. | |
3044 | ||
3045 | `-c' | |
3046 | Specify the number of lines read between each call to | |
3047 | CALLBACK. | |
3048 | ||
3049 | If `-C' is specified without `-c', the default quantum is 5000. | |
3050 | ||
3051 | If not supplied with an explicit origin, `mapfile' will clear ARRAY | |
3052 | before assigning to it. | |
3053 | ||
3054 | `mapfile' returns successfully unless an invalid option or option | |
3055 | argument is supplied, or ARRAY is invalid or unassignable. | |
3056 | ||
bb70624e | 3057 | `printf' |
29d25b54 | 3058 | printf [-v VAR] FORMAT [ARGUMENTS] |
bb70624e JA |
3059 | Write the formatted ARGUMENTS to the standard output under the |
3060 | control of the FORMAT. The FORMAT is a character string which | |
3061 | contains three types of objects: plain characters, which are | |
3062 | simply copied to standard output, character escape sequences, | |
3063 | which are converted and copied to the standard output, and format | |
3064 | specifications, each of which causes printing of the next | |
3065 | successive ARGUMENT. In addition to the standard `printf(1)' | |
3066 | formats, `%b' causes `printf' to expand backslash escape sequences | |
5e13499c CR |
3067 | in the corresponding ARGUMENT, (except that `\c' terminates |
3068 | output, backslashes in `\'', `\"', and `\?' are not removed, and | |
3069 | octal escapes beginning with `\0' may contain up to four digits), | |
3070 | and `%q' causes `printf' to output the corresponding ARGUMENT in a | |
3071 | format that can be reused as shell input. | |
ccc6cda3 | 3072 | |
3ee6b87d CR |
3073 | The `-v' option causes the output to be assigned to the variable |
3074 | VAR rather than being printed to the standard output. | |
3075 | ||
bb70624e JA |
3076 | The FORMAT is reused as necessary to consume all of the ARGUMENTS. |
3077 | If the FORMAT requires more ARGUMENTS than are supplied, the extra | |
3078 | format specifications behave as if a zero value or null string, as | |
3079 | appropriate, had been supplied. The return value is zero on | |
3080 | success, non-zero on failure. | |
ccc6cda3 | 3081 | |
bb70624e | 3082 | `read' |
6a8fd0ed | 3083 | read [-ers] [-a ANAME] [-d DELIM] [-i TEXT] [-n NCHARS] [-p PROMPT] [-t TIMEOUT] [-u FD] [NAME ...] |
7117c2d2 JA |
3084 | One line is read from the standard input, or from the file |
3085 | descriptor FD supplied as an argument to the `-u' option, and the | |
3086 | first word is assigned to the first NAME, the second word to the | |
3087 | second NAME, and so on, with leftover words and their intervening | |
3088 | separators assigned to the last NAME. If there are fewer words | |
3089 | read from the input stream than names, the remaining names are | |
3090 | assigned empty values. The characters in the value of the `IFS' | |
3091 | variable are used to split the line into words. The backslash | |
3092 | character `\' may be used to remove any special meaning for the | |
3093 | next character read and for line continuation. If no names are | |
3094 | supplied, the line read is assigned to the variable `REPLY'. The | |
3095 | return code is zero, unless end-of-file is encountered, `read' | |
3096 | times out, or an invalid file descriptor is supplied as the | |
3097 | argument to `-u'. Options, if supplied, have the following | |
3098 | meanings: | |
ccc6cda3 | 3099 | |
bb70624e JA |
3100 | `-a ANAME' |
3101 | The words are assigned to sequential indices of the array | |
3102 | variable ANAME, starting at 0. All elements are removed from | |
3103 | ANAME before the assignment. Other NAME arguments are | |
3104 | ignored. | |
ccc6cda3 | 3105 | |
bb70624e JA |
3106 | `-d DELIM' |
3107 | The first character of DELIM is used to terminate the input | |
3108 | line, rather than newline. | |
ccc6cda3 | 3109 | |
bb70624e | 3110 | `-e' |
28ef6c31 JA |
3111 | Readline (*note Command Line Editing::) is used to obtain the |
3112 | line. | |
ccc6cda3 | 3113 | |
6a8fd0ed CR |
3114 | `-i TEXT' |
3115 | If Readline is being used to read the line, TEXT is placed | |
3116 | into the editing buffer before editing begins. | |
3117 | ||
bb70624e JA |
3118 | `-n NCHARS' |
3119 | `read' returns after reading NCHARS characters rather than | |
3120 | waiting for a complete line of input. | |
cce855bc | 3121 | |
bb70624e JA |
3122 | `-p PROMPT' |
3123 | Display PROMPT, without a trailing newline, before attempting | |
3124 | to read any input. The prompt is displayed only if input is | |
3125 | coming from a terminal. | |
ccc6cda3 | 3126 | |
bb70624e JA |
3127 | `-r' |
3128 | If this option is given, backslash does not act as an escape | |
3129 | character. The backslash is considered to be part of the | |
3130 | line. In particular, a backslash-newline pair may not be | |
3131 | used as a line continuation. | |
ccc6cda3 | 3132 | |
bb70624e JA |
3133 | `-s' |
3134 | Silent mode. If input is coming from a terminal, characters | |
3135 | are not echoed. | |
cce855bc | 3136 | |
bb70624e JA |
3137 | `-t TIMEOUT' |
3138 | Cause `read' to time out and return failure if a complete | |
ed35cb4a CR |
3139 | line of input is not read within TIMEOUT seconds. TIMEOUT |
3140 | may be a decimal number with a fractional portion following | |
3141 | the decimal point. This option has no effect if `read' is | |
3142 | not reading input from the terminal or a pipe. | |
cce855bc | 3143 | |
7117c2d2 JA |
3144 | `-u FD' |
3145 | Read input from file descriptor FD. | |
3146 | ||
761783bf | 3147 | |
bb70624e JA |
3148 | `source' |
3149 | source FILENAME | |
28ef6c31 | 3150 | A synonym for `.' (*note Bourne Shell Builtins::). |
ccc6cda3 | 3151 | |
bb70624e | 3152 | `type' |
7117c2d2 | 3153 | type [-afptP] [NAME ...] |
bb70624e JA |
3154 | For each NAME, indicate how it would be interpreted if used as a |
3155 | command name. | |
cce855bc | 3156 | |
bb70624e JA |
3157 | If the `-t' option is used, `type' prints a single word which is |
3158 | one of `alias', `function', `builtin', `file' or `keyword', if | |
3159 | NAME is an alias, shell function, shell builtin, disk file, or | |
3160 | shell reserved word, respectively. If the NAME is not found, then | |
3161 | nothing is printed, and `type' returns a failure status. | |
ccc6cda3 | 3162 | |
bb70624e JA |
3163 | If the `-p' option is used, `type' either returns the name of the |
3164 | disk file that would be executed, or nothing if `-t' would not | |
3165 | return `file'. | |
ccc6cda3 | 3166 | |
7117c2d2 JA |
3167 | The `-P' option forces a path search for each NAME, even if `-t' |
3168 | would not return `file'. | |
3169 | ||
3170 | If a command is hashed, `-p' and `-P' print the hashed value, not | |
3171 | necessarily the file that appears first in `$PATH'. | |
3172 | ||
bb70624e JA |
3173 | If the `-a' option is used, `type' returns all of the places that |
3174 | contain an executable named FILE. This includes aliases and | |
3175 | functions, if and only if the `-p' option is not also used. | |
ccc6cda3 | 3176 | |
7117c2d2 JA |
3177 | If the `-f' option is used, `type' does not attempt to find shell |
3178 | functions, as with the `command' builtin. | |
3179 | ||
ed35cb4a CR |
3180 | The return status is zero if all of the NAMES are found, non-zero |
3181 | if any are not found. | |
ccc6cda3 | 3182 | |
bb70624e | 3183 | `typeset' |
d3a24ed2 | 3184 | typeset [-afFrxi] [-p] [NAME[=VALUE] ...] |
bb70624e JA |
3185 | The `typeset' command is supplied for compatibility with the Korn |
3186 | shell; however, it has been deprecated in favor of the `declare' | |
3187 | builtin command. | |
ccc6cda3 | 3188 | |
bb70624e | 3189 | `ulimit' |
6a8fd0ed | 3190 | ulimit [-abcdefilmnpqrstuvxHST] [LIMIT] |
bb70624e JA |
3191 | `ulimit' provides control over the resources available to processes |
3192 | started by the shell, on systems that allow such control. If an | |
3193 | option is given, it is interpreted as follows: | |
3194 | `-S' | |
3195 | Change and report the soft limit associated with a resource. | |
ccc6cda3 | 3196 | |
bb70624e JA |
3197 | `-H' |
3198 | Change and report the hard limit associated with a resource. | |
ccc6cda3 | 3199 | |
bb70624e JA |
3200 | `-a' |
3201 | All current limits are reported. | |
ccc6cda3 | 3202 | |
6a8fd0ed CR |
3203 | `-b' |
3204 | The maximum socket buffer size. | |
3205 | ||
bb70624e JA |
3206 | `-c' |
3207 | The maximum size of core files created. | |
ccc6cda3 | 3208 | |
bb70624e JA |
3209 | `-d' |
3210 | The maximum size of a process's data segment. | |
ccc6cda3 | 3211 | |
ac18b312 CR |
3212 | `-e' |
3213 | The maximum scheduling priority ("nice"). | |
3214 | ||
bb70624e | 3215 | `-f' |
d3ad40de CR |
3216 | The maximum size of files written by the shell and its |
3217 | children. | |
ccc6cda3 | 3218 | |
ac18b312 CR |
3219 | `-i' |
3220 | The maximum number of pending signals. | |
3221 | ||
bb70624e JA |
3222 | `-l' |
3223 | The maximum size that may be locked into memory. | |
ccc6cda3 | 3224 | |
bb70624e JA |
3225 | `-m' |
3226 | The maximum resident set size. | |
ccc6cda3 | 3227 | |
bb70624e JA |
3228 | `-n' |
3229 | The maximum number of open file descriptors. | |
ccc6cda3 | 3230 | |
bb70624e JA |
3231 | `-p' |
3232 | The pipe buffer size. | |
ccc6cda3 | 3233 | |
ac18b312 CR |
3234 | `-q' |
3235 | The maximum number of bytes in POSIX message queues. | |
3236 | ||
3237 | `-r' | |
3238 | The maximum real-time scheduling priority. | |
3239 | ||
bb70624e JA |
3240 | `-s' |
3241 | The maximum stack size. | |
ccc6cda3 | 3242 | |
bb70624e JA |
3243 | `-t' |
3244 | The maximum amount of cpu time in seconds. | |
ccc6cda3 | 3245 | |
bb70624e JA |
3246 | `-u' |
3247 | The maximum number of processes available to a single user. | |
cce855bc | 3248 | |
bb70624e JA |
3249 | `-v' |
3250 | The maximum amount of virtual memory available to the process. | |
ccc6cda3 | 3251 | |
ac18b312 CR |
3252 | `-x' |
3253 | The maximum number of file locks. | |
3254 | ||
6a8fd0ed CR |
3255 | `-T' |
3256 | The maximum number of threads. | |
3257 | ||
761783bf | 3258 | |
f73dda09 JA |
3259 | If LIMIT is given, it is the new value of the specified resource; |
3260 | the special LIMIT values `hard', `soft', and `unlimited' stand for | |
3261 | the current hard limit, the current soft limit, and no limit, | |
3d4e09aa CR |
3262 | respectively. A hard limit cannot be increased by a non-root user |
3263 | once it is set; a soft limit may be increased up to the value of | |
3264 | the hard limit. Otherwise, the current value of the soft limit | |
3265 | for the specified resource is printed, unless the `-H' option is | |
f73dda09 JA |
3266 | supplied. When setting new limits, if neither `-H' nor `-S' is |
3267 | supplied, both the hard and soft limits are set. If no option is | |
3268 | given, then `-f' is assumed. Values are in 1024-byte increments, | |
3269 | except for `-t', which is in seconds, `-p', which is in units of | |
3270 | 512-byte blocks, and `-n' and `-u', which are unscaled values. | |
ccc6cda3 | 3271 | |
f73dda09 JA |
3272 | The return status is zero unless an invalid option or argument is |
3273 | supplied, or an error occurs while setting a new limit. | |
ccc6cda3 | 3274 | |
bb70624e JA |
3275 | `unalias' |
3276 | unalias [-a] [NAME ... ] | |
ccc6cda3 | 3277 | |
bb70624e | 3278 | Remove each NAME from the list of aliases. If `-a' is supplied, |
6a8fd0ed | 3279 | all aliases are removed. Aliases are described in *note Aliases::. |
ccc6cda3 | 3280 | |
761783bf | 3281 | |
bb70624e | 3282 | \1f |
d3ad40de | 3283 | File: bashref.info, Node: Modifying Shell Behavior, Next: Special Builtins, Prev: Bash Builtins, Up: Shell Builtin Commands |
ccc6cda3 | 3284 | |
d3ad40de CR |
3285 | 4.3 Modifying Shell Behavior |
3286 | ============================ | |
3287 | ||
3288 | * Menu: | |
3289 | ||
3290 | * The Set Builtin:: Change the values of shell attributes and | |
3291 | positional parameters. | |
3292 | * The Shopt Builtin:: Modify shell optional behavior. | |
3293 | ||
3294 | \1f | |
3295 | File: bashref.info, Node: The Set Builtin, Next: The Shopt Builtin, Up: Modifying Shell Behavior | |
3296 | ||
3297 | 4.3.1 The Set Builtin | |
3298 | --------------------- | |
9d6e5e30 | 3299 | |
d3ad40de CR |
3300 | This builtin is so complicated that it deserves its own section. `set' |
3301 | allows you to change the values of shell options and set the positional | |
3302 | parameters, or to display the names and values of shell variables. | |
ccc6cda3 | 3303 | |
bb70624e | 3304 | `set' |
d3ad40de CR |
3305 | set [--abefhkmnptuvxBCEHPT] [-o OPTION] [ARGUMENT ...] |
3306 | set [+abefhkmnptuvxBCEHPT] [+o OPTION] [ARGUMENT ...] | |
ccc6cda3 | 3307 | |
bb70624e JA |
3308 | If no options or arguments are supplied, `set' displays the names |
3309 | and values of all shell variables and functions, sorted according | |
54cdd75a CR |
3310 | to the current locale, in a format that may be reused as input for |
3311 | setting or resetting the currently-set variables. Read-only | |
3312 | variables cannot be reset. In POSIX mode, only shell variables | |
3313 | are listed. | |
ccc6cda3 | 3314 | |
bb70624e JA |
3315 | When options are supplied, they set or unset shell attributes. |
3316 | Options, if specified, have the following meanings: | |
ccc6cda3 | 3317 | |
bb70624e | 3318 | `-a' |
28ef6c31 JA |
3319 | Mark variables and function which are modified or created for |
3320 | export to the environment of subsequent commands. | |
ccc6cda3 | 3321 | |
bb70624e JA |
3322 | `-b' |
3323 | Cause the status of terminated background jobs to be reported | |
3324 | immediately, rather than before printing the next primary | |
3325 | prompt. | |
ccc6cda3 | 3326 | |
bb70624e JA |
3327 | `-e' |
3328 | Exit immediately if a simple command (*note Simple | |
28ef6c31 | 3329 | Commands::) exits with a non-zero status, unless the command |
d3a24ed2 CR |
3330 | that fails is part of the command list immediately following |
3331 | a `while' or `until' keyword, part of the test in an `if' | |
c2a47ea9 CR |
3332 | statement, part of a command executed in a `&&' or `||b' list, |
3333 | any command in a pipeline but the last, or if the command's | |
3334 | return status is being inverted using `!'. Failing simple | |
3335 | commands that are part of shell functions or command lists | |
3336 | enclosed in braces or parentheses satisfying the above | |
3337 | conditions do not cause the shell to exit. A trap on `ERR', | |
3338 | if set, is executed before the shell exits. | |
ccc6cda3 | 3339 | |
bb70624e JA |
3340 | `-f' |
3341 | Disable file name generation (globbing). | |
ccc6cda3 | 3342 | |
bb70624e JA |
3343 | `-h' |
3344 | Locate and remember (hash) commands as they are looked up for | |
3345 | execution. This option is enabled by default. | |
ccc6cda3 | 3346 | |
bb70624e JA |
3347 | `-k' |
3348 | All arguments in the form of assignment statements are placed | |
3349 | in the environment for a command, not just those that precede | |
3350 | the command name. | |
ccc6cda3 | 3351 | |
bb70624e | 3352 | `-m' |
28ef6c31 | 3353 | Job control is enabled (*note Job Control::). |
b72432fd | 3354 | |
bb70624e JA |
3355 | `-n' |
3356 | Read commands but do not execute them; this may be used to | |
3357 | check a script for syntax errors. This option is ignored by | |
3358 | interactive shells. | |
ccc6cda3 | 3359 | |
bb70624e JA |
3360 | `-o OPTION-NAME' |
3361 | Set the option corresponding to OPTION-NAME: | |
ccc6cda3 | 3362 | |
bb70624e JA |
3363 | `allexport' |
3364 | Same as `-a'. | |
ccc6cda3 | 3365 | |
bb70624e JA |
3366 | `braceexpand' |
3367 | Same as `-B'. | |
ccc6cda3 | 3368 | |
bb70624e JA |
3369 | `emacs' |
3370 | Use an `emacs'-style line editing interface (*note | |
28ef6c31 | 3371 | Command Line Editing::). |
ccc6cda3 | 3372 | |
bb70624e JA |
3373 | `errexit' |
3374 | Same as `-e'. | |
d166f048 | 3375 | |
d3a24ed2 CR |
3376 | `errtrace' |
3377 | Same as `-E'. | |
3378 | ||
3379 | `functrace' | |
3380 | Same as `-T'. | |
3381 | ||
bb70624e JA |
3382 | `hashall' |
3383 | Same as `-h'. | |
d166f048 | 3384 | |
bb70624e JA |
3385 | `histexpand' |
3386 | Same as `-H'. | |
ccc6cda3 | 3387 | |
bb70624e | 3388 | `history' |
6a8fd0ed | 3389 | Enable command history, as described in *note Bash |
bb70624e JA |
3390 | History Facilities::. This option is on by default in |
3391 | interactive shells. | |
ccc6cda3 | 3392 | |
bb70624e JA |
3393 | `ignoreeof' |
3394 | An interactive shell will not exit upon reading EOF. | |
ccc6cda3 | 3395 | |
bb70624e JA |
3396 | `keyword' |
3397 | Same as `-k'. | |
ccc6cda3 | 3398 | |
bb70624e JA |
3399 | `monitor' |
3400 | Same as `-m'. | |
ccc6cda3 | 3401 | |
bb70624e JA |
3402 | `noclobber' |
3403 | Same as `-C'. | |
ccc6cda3 | 3404 | |
bb70624e JA |
3405 | `noexec' |
3406 | Same as `-n'. | |
ccc6cda3 | 3407 | |
28157acd CR |
3408 | `noglob' |
3409 | Same as `-f'. | |
9d6e5e30 | 3410 | |
d3ad40de CR |
3411 | `nolog' |
3412 | Currently ignored. | |
3413 | ||
3414 | `notify' | |
3415 | Same as `-b'. | |
3416 | ||
3417 | `nounset' | |
3418 | Same as `-u'. | |
3419 | ||
3420 | `onecmd' | |
3421 | Same as `-t'. | |
3422 | ||
3423 | `physical' | |
3424 | Same as `-P'. | |
3425 | ||
3426 | `pipefail' | |
3427 | If set, the return value of a pipeline is the value of | |
3428 | the last (rightmost) command to exit with a non-zero | |
3429 | status, or zero if all commands in the pipeline exit | |
3430 | successfully. This option is disabled by default. | |
3431 | ||
3432 | `posix' | |
3433 | Change the behavior of Bash where the default operation | |
3434 | differs from the POSIX standard to match the standard | |
3435 | (*note Bash POSIX Mode::). This is intended to make | |
3436 | Bash behave as a strict superset of that standard. | |
3437 | ||
3438 | `privileged' | |
3439 | Same as `-p'. | |
3440 | ||
3441 | `verbose' | |
3442 | Same as `-v'. | |
3443 | ||
3444 | `vi' | |
3445 | Use a `vi'-style line editing interface. | |
3446 | ||
3447 | `xtrace' | |
3448 | Same as `-x'. | |
3449 | ||
3450 | `-p' | |
3451 | Turn on privileged mode. In this mode, the `$BASH_ENV' and | |
3452 | `$ENV' files are not processed, shell functions are not | |
3453 | inherited from the environment, and the `SHELLOPTS' variable, | |
3454 | if it appears in the environment, is ignored. If the shell | |
3455 | is started with the effective user (group) id not equal to the | |
3456 | real user (group) id, and the `-p' option is not supplied, | |
3457 | these actions are taken and the effective user id is set to | |
3458 | the real user id. If the `-p' option is supplied at startup, | |
3459 | the effective user id is not reset. Turning this option off | |
3460 | causes the effective user and group ids to be set to the real | |
3461 | user and group ids. | |
3462 | ||
3463 | `-t' | |
3464 | Exit after reading and executing one command. | |
3465 | ||
3466 | `-u' | |
3467 | Treat unset variables as an error when performing parameter | |
3468 | expansion. An error message will be written to the standard | |
3469 | error, and a non-interactive shell will exit. | |
3470 | ||
3471 | `-v' | |
3472 | Print shell input lines as they are read. | |
3473 | ||
3474 | `-x' | |
3475 | Print a trace of simple commands, `for' commands, `case' | |
3476 | commands, `select' commands, and arithmetic `for' commands | |
3477 | and their arguments or associated word lists after they are | |
3478 | expanded and before they are executed. The value of the `PS4' | |
3479 | variable is expanded and the resultant value is printed before | |
3480 | the command and its expanded arguments. | |
3481 | ||
3482 | `-B' | |
3483 | The shell will perform brace expansion (*note Brace | |
3484 | Expansion::). This option is on by default. | |
3485 | ||
3486 | `-C' | |
3487 | Prevent output redirection using `>', `>&', and `<>' from | |
3488 | overwriting existing files. | |
3489 | ||
3490 | `-E' | |
3491 | If set, any trap on `ERR' is inherited by shell functions, | |
3492 | command substitutions, and commands executed in a subshell | |
3493 | environment. The `ERR' trap is normally not inherited in | |
3494 | such cases. | |
3495 | ||
3496 | `-H' | |
3497 | Enable `!' style history substitution (*note History | |
3498 | Interaction::). This option is on by default for interactive | |
3499 | shells. | |
3500 | ||
3501 | `-P' | |
3502 | If set, do not follow symbolic links when performing commands | |
3503 | such as `cd' which change the current directory. The | |
3504 | physical directory is used instead. By default, Bash follows | |
3505 | the logical chain of directories when performing commands | |
3506 | which change the current directory. | |
3507 | ||
3508 | For example, if `/usr/sys' is a symbolic link to | |
3509 | `/usr/local/sys' then: | |
3510 | $ cd /usr/sys; echo $PWD | |
3511 | /usr/sys | |
3512 | $ cd ..; pwd | |
3513 | /usr | |
3514 | ||
3515 | If `set -P' is on, then: | |
3516 | $ cd /usr/sys; echo $PWD | |
3517 | /usr/local/sys | |
3518 | $ cd ..; pwd | |
3519 | /usr/local | |
3520 | ||
3521 | `-T' | |
3522 | If set, any trap on `DEBUG' and `RETURN' are inherited by | |
3523 | shell functions, command substitutions, and commands executed | |
3524 | in a subshell environment. The `DEBUG' and `RETURN' traps | |
3525 | are normally not inherited in such cases. | |
3526 | ||
3527 | `--' | |
3528 | If no arguments follow this option, then the positional | |
3529 | parameters are unset. Otherwise, the positional parameters | |
3530 | are set to the ARGUMENTS, even if some of them begin with a | |
3531 | `-'. | |
3532 | ||
3533 | `-' | |
3534 | Signal the end of options, cause all remaining ARGUMENTS to | |
3535 | be assigned to the positional parameters. The `-x' and `-v' | |
3536 | options are turned off. If there are no arguments, the | |
3537 | positional parameters remain unchanged. | |
3538 | ||
3539 | Using `+' rather than `-' causes these options to be turned off. | |
3540 | The options can also be used upon invocation of the shell. The | |
3541 | current set of options may be found in `$-'. | |
3542 | ||
3543 | The remaining N ARGUMENTS are positional parameters and are | |
3544 | assigned, in order, to `$1', `$2', ... `$N'. The special | |
3545 | parameter `#' is set to N. | |
3546 | ||
3547 | The return status is always zero unless an invalid option is | |
3548 | supplied. | |
3549 | ||
3550 | \1f | |
3551 | File: bashref.info, Node: The Shopt Builtin, Prev: The Set Builtin, Up: Modifying Shell Behavior | |
3552 | ||
3553 | 4.3.2 The Shopt Builtin | |
3554 | ----------------------- | |
3555 | ||
3556 | This builtin allows you to change additional shell optional behavior. | |
3557 | ||
3558 | `shopt' | |
3559 | shopt [-pqsu] [-o] [OPTNAME ...] | |
3560 | Toggle the values of variables controlling optional shell behavior. | |
3561 | With no options, or with the `-p' option, a list of all settable | |
3562 | options is displayed, with an indication of whether or not each is | |
3563 | set. The `-p' option causes output to be displayed in a form that | |
3564 | may be reused as input. Other options have the following meanings: | |
3565 | ||
3566 | `-s' | |
3567 | Enable (set) each OPTNAME. | |
3568 | ||
3569 | `-u' | |
3570 | Disable (unset) each OPTNAME. | |
3571 | ||
3572 | `-q' | |
3573 | Suppresses normal output; the return status indicates whether | |
3574 | the OPTNAME is set or unset. If multiple OPTNAME arguments | |
3575 | are given with `-q', the return status is zero if all | |
3576 | OPTNAMES are enabled; non-zero otherwise. | |
3577 | ||
3578 | `-o' | |
3579 | Restricts the values of OPTNAME to be those defined for the | |
3580 | `-o' option to the `set' builtin (*note The Set Builtin::). | |
3581 | ||
3582 | If either `-s' or `-u' is used with no OPTNAME arguments, the | |
3583 | display is limited to those options which are set or unset, | |
3584 | respectively. | |
3585 | ||
3586 | Unless otherwise noted, the `shopt' options are disabled (off) by | |
3587 | default. | |
3588 | ||
3589 | The return status when listing options is zero if all OPTNAMES are | |
3590 | enabled, non-zero otherwise. When setting or unsetting options, | |
3591 | the return status is zero unless an OPTNAME is not a valid shell | |
3592 | option. | |
3593 | ||
3594 | The list of `shopt' options is: | |
3595 | `autocd' | |
3596 | If set, a command name that is the name of a directory is | |
3597 | executed as if it were the argument to the `cd' command. | |
3598 | This option is only used by interactive shells. | |
3599 | ||
3600 | `cdable_vars' | |
3601 | If this is set, an argument to the `cd' builtin command that | |
3602 | is not a directory is assumed to be the name of a variable | |
3603 | whose value is the directory to change to. | |
3604 | ||
3605 | `cdspell' | |
3606 | If set, minor errors in the spelling of a directory component | |
3607 | in a `cd' command will be corrected. The errors checked for | |
3608 | are transposed characters, a missing character, and a | |
3609 | character too many. If a correction is found, the corrected | |
3610 | path is printed, and the command proceeds. This option is | |
3611 | only used by interactive shells. | |
3612 | ||
3613 | `checkhash' | |
3614 | If this is set, Bash checks that a command found in the hash | |
3615 | table exists before trying to execute it. If a hashed | |
3616 | command no longer exists, a normal path search is performed. | |
3617 | ||
3618 | `checkjobs' | |
3619 | If set, Bash lists the status of any stopped and running jobs | |
3620 | before exiting an interactive shell. If any jobs are | |
3621 | running, this causes the exit to be deferred until a second | |
3622 | exit is attempted without an intervening command (*note Job | |
3623 | Control::). The shell always postpones exiting if any jobs | |
3624 | are stopped. | |
3625 | ||
3626 | `checkwinsize' | |
3627 | If set, Bash checks the window size after each command and, | |
3628 | if necessary, updates the values of `LINES' and `COLUMNS'. | |
3629 | ||
3630 | `cmdhist' | |
3631 | If set, Bash attempts to save all lines of a multiple-line | |
3632 | command in the same history entry. This allows easy | |
3633 | re-editing of multi-line commands. | |
3634 | ||
29d25b54 CR |
3635 | `compat31' |
3636 | If set, Bash changes its behavior to that of version 3.1 with | |
3637 | respect to quoted arguments to the conditional command's =~ | |
3638 | operator. | |
3639 | ||
ed35cb4a CR |
3640 | `dirspell' |
3641 | If set, Bash attempts spelling correction on directory names | |
3642 | during word completion if the directory name initially | |
3643 | supplied does not exist. | |
3644 | ||
d3ad40de CR |
3645 | `dotglob' |
3646 | If set, Bash includes filenames beginning with a `.' in the | |
3647 | results of filename expansion. | |
3648 | ||
3649 | `execfail' | |
3650 | If this is set, a non-interactive shell will not exit if it | |
3651 | cannot execute the file specified as an argument to the `exec' | |
3652 | builtin command. An interactive shell does not exit if `exec' | |
3653 | fails. | |
3654 | ||
3655 | `expand_aliases' | |
3656 | If set, aliases are expanded as described below under Aliases, | |
6a8fd0ed | 3657 | *note Aliases::. This option is enabled by default for |
d3ad40de CR |
3658 | interactive shells. |
3659 | ||
3660 | `extdebug' | |
3661 | If set, behavior intended for use by debuggers is enabled: | |
3662 | ||
3663 | 1. The `-F' option to the `declare' builtin (*note Bash | |
3664 | Builtins::) displays the source file name and line | |
3665 | number corresponding to each function name supplied as | |
3666 | an argument. | |
3667 | ||
3668 | 2. If the command run by the `DEBUG' trap returns a | |
3669 | non-zero value, the next command is skipped and not | |
3670 | executed. | |
3671 | ||
3672 | 3. If the command run by the `DEBUG' trap returns a value | |
3673 | of 2, and the shell is executing in a subroutine (a | |
3674 | shell function or a shell script executed by the `.' or | |
3675 | `source' builtins), a call to `return' is simulated. | |
3676 | ||
3677 | 4. `BASH_ARGC' and `BASH_ARGV' are updated as described in | |
3678 | their descriptions (*note Bash Variables::). | |
3679 | ||
3680 | 5. Function tracing is enabled: command substitution, | |
3681 | shell functions, and subshells invoked with `( COMMAND | |
3682 | )' inherit the `DEBUG' and `RETURN' traps. | |
9d6e5e30 | 3683 | |
d3ad40de CR |
3684 | 6. Error tracing is enabled: command substitution, shell |
3685 | functions, and subshells invoked with `( COMMAND )' | |
3686 | inherit the `ERROR' trap. | |
9d6e5e30 | 3687 | |
d3ad40de CR |
3688 | `extglob' |
3689 | If set, the extended pattern matching features described above | |
3690 | (*note Pattern Matching::) are enabled. | |
9d6e5e30 | 3691 | |
d3ad40de CR |
3692 | `extquote' |
3693 | If set, `$'STRING'' and `$"STRING"' quoting is performed | |
3694 | within `${PARAMETER}' expansions enclosed in double quotes. | |
3695 | This option is enabled by default. | |
9d6e5e30 | 3696 | |
d3ad40de CR |
3697 | `failglob' |
3698 | If set, patterns which fail to match filenames during | |
3699 | pathname expansion result in an expansion error. | |
9d6e5e30 | 3700 | |
d3ad40de CR |
3701 | `force_fignore' |
3702 | If set, the suffixes specified by the `FIGNORE' shell variable | |
3703 | cause words to be ignored when performing word completion | |
3704 | even if the ignored words are the only possible completions. | |
3705 | *Note Bash Variables::, for a description of `FIGNORE'. This | |
3706 | option is enabled by default. | |
9d6e5e30 | 3707 | |
ed35cb4a CR |
3708 | `globstar' |
3709 | If set, the pattern `**' used in a filename expansion context | |
3710 | will match a files and zero or more directories and | |
3711 | subdirectories. If the pattern is followed by a `/', only | |
3712 | directories and subdirectories match. | |
3713 | ||
d3ad40de CR |
3714 | `gnu_errfmt' |
3715 | If set, shell error messages are written in the standard GNU | |
3716 | error message format. | |
9d6e5e30 | 3717 | |
d3ad40de CR |
3718 | `histappend' |
3719 | If set, the history list is appended to the file named by the | |
3720 | value of the `HISTFILE' variable when the shell exits, rather | |
3721 | than overwriting the file. | |
9d6e5e30 | 3722 | |
d3ad40de CR |
3723 | `histreedit' |
3724 | If set, and Readline is being used, a user is given the | |
3725 | opportunity to re-edit a failed history substitution. | |
9d6e5e30 | 3726 | |
d3ad40de CR |
3727 | `histverify' |
3728 | If set, and Readline is being used, the results of history | |
3729 | substitution are not immediately passed to the shell parser. | |
3730 | Instead, the resulting line is loaded into the Readline | |
3731 | editing buffer, allowing further modification. | |
9d6e5e30 | 3732 | |
d3ad40de CR |
3733 | `hostcomplete' |
3734 | If set, and Readline is being used, Bash will attempt to | |
3735 | perform hostname completion when a word containing a `@' is | |
3736 | being completed (*note Commands For Completion::). This | |
3737 | option is enabled by default. | |
9d6e5e30 | 3738 | |
d3ad40de CR |
3739 | `huponexit' |
3740 | If set, Bash will send `SIGHUP' to all jobs when an | |
3741 | interactive login shell exits (*note Signals::). | |
9d6e5e30 | 3742 | |
d3ad40de CR |
3743 | `interactive_comments' |
3744 | Allow a word beginning with `#' to cause that word and all | |
3745 | remaining characters on that line to be ignored in an | |
3746 | interactive shell. This option is enabled by default. | |
9d6e5e30 | 3747 | |
d3ad40de CR |
3748 | `lithist' |
3749 | If enabled, and the `cmdhist' option is enabled, multi-line | |
3750 | commands are saved to the history with embedded newlines | |
3751 | rather than using semicolon separators where possible. | |
9d6e5e30 | 3752 | |
d3ad40de CR |
3753 | `login_shell' |
3754 | The shell sets this option if it is started as a login shell | |
3755 | (*note Invoking Bash::). The value may not be changed. | |
9d6e5e30 | 3756 | |
d3ad40de CR |
3757 | `mailwarn' |
3758 | If set, and a file that Bash is checking for mail has been | |
3759 | accessed since the last time it was checked, the message | |
3760 | `"The mail in MAILFILE has been read"' is displayed. | |
9d6e5e30 | 3761 | |
d3ad40de CR |
3762 | `no_empty_cmd_completion' |
3763 | If set, and Readline is being used, Bash will not attempt to | |
3764 | search the `PATH' for possible completions when completion is | |
3765 | attempted on an empty line. | |
9d6e5e30 | 3766 | |
d3ad40de CR |
3767 | `nocaseglob' |
3768 | If set, Bash matches filenames in a case-insensitive fashion | |
3769 | when performing filename expansion. | |
9d6e5e30 | 3770 | |
d3ad40de CR |
3771 | `nocasematch' |
3772 | If set, Bash matches patterns in a case-insensitive fashion | |
3773 | when performing matching while executing `case' or `[[' | |
3774 | conditional commands. | |
9d6e5e30 | 3775 | |
d3ad40de CR |
3776 | `nullglob' |
3777 | If set, Bash allows filename patterns which match no files to | |
3778 | expand to a null string, rather than themselves. | |
9d6e5e30 | 3779 | |
d3ad40de CR |
3780 | `progcomp' |
3781 | If set, the programmable completion facilities (*note | |
3782 | Programmable Completion::) are enabled. This option is | |
3783 | enabled by default. | |
9d6e5e30 | 3784 | |
d3ad40de CR |
3785 | `promptvars' |
3786 | If set, prompt strings undergo parameter expansion, command | |
3787 | substitution, arithmetic expansion, and quote removal after | |
3788 | being expanded as described below (*note Printing a Prompt::). | |
3789 | This option is enabled by default. | |
9d6e5e30 | 3790 | |
d3ad40de CR |
3791 | `restricted_shell' |
3792 | The shell sets this option if it is started in restricted mode | |
3793 | (*note The Restricted Shell::). The value may not be changed. | |
3794 | This is not reset when the startup files are executed, | |
3795 | allowing the startup files to discover whether or not a shell | |
3796 | is restricted. | |
9d6e5e30 | 3797 | |
d3ad40de CR |
3798 | `shift_verbose' |
3799 | If this is set, the `shift' builtin prints an error message | |
3800 | when the shift count exceeds the number of positional | |
3801 | parameters. | |
9d6e5e30 | 3802 | |
d3ad40de CR |
3803 | `sourcepath' |
3804 | If set, the `source' builtin uses the value of `PATH' to find | |
3805 | the directory containing the file supplied as an argument. | |
3806 | This option is enabled by default. | |
9d6e5e30 | 3807 | |
d3ad40de CR |
3808 | `xpg_echo' |
3809 | If set, the `echo' builtin expands backslash-escape sequences | |
3810 | by default. | |
9d6e5e30 CR |
3811 | |
3812 | ||
d3ad40de CR |
3813 | The return status when listing options is zero if all OPTNAMES are |
3814 | enabled, non-zero otherwise. When setting or unsetting options, | |
3815 | the return status is zero unless an OPTNAME is not a valid shell | |
3816 | option. | |
9d6e5e30 CR |
3817 | |
3818 | ||
3819 | \1f | |
d3ad40de | 3820 | File: bashref.info, Node: Special Builtins, Prev: Modifying Shell Behavior, Up: Shell Builtin Commands |
ccc6cda3 | 3821 | |
37c41ab1 CR |
3822 | 4.4 Special Builtins |
3823 | ==================== | |
ccc6cda3 | 3824 | |
ac18b312 CR |
3825 | For historical reasons, the POSIX standard has classified several |
3826 | builtin commands as _special_. When Bash is executing in POSIX mode, | |
3827 | the special builtins differ from other builtin commands in three | |
bb70624e | 3828 | respects: |
ccc6cda3 | 3829 | |
bb70624e JA |
3830 | 1. Special builtins are found before shell functions during command |
3831 | lookup. | |
ccc6cda3 | 3832 | |
bb70624e JA |
3833 | 2. If a special builtin returns an error status, a non-interactive |
3834 | shell exits. | |
ccc6cda3 | 3835 | |
bb70624e JA |
3836 | 3. Assignment statements preceding the command stay in effect in the |
3837 | shell environment after the command completes. | |
ccc6cda3 | 3838 | |
bb70624e JA |
3839 | When Bash is not executing in POSIX mode, these builtins behave no |
3840 | differently than the rest of the Bash builtin commands. The Bash POSIX | |
6a8fd0ed | 3841 | mode is described in *note Bash POSIX Mode::. |
ccc6cda3 | 3842 | |
bb70624e JA |
3843 | These are the POSIX special builtins: |
3844 | break : . continue eval exec exit export readonly return set | |
3845 | shift trap unset | |
ccc6cda3 | 3846 | |
bb70624e JA |
3847 | \1f |
3848 | File: bashref.info, Node: Shell Variables, Next: Bash Features, Prev: Shell Builtin Commands, Up: Top | |
cce855bc | 3849 | |
37c41ab1 CR |
3850 | 5 Shell Variables |
3851 | ***************** | |
ccc6cda3 | 3852 | |
bb70624e | 3853 | * Menu: |
ccc6cda3 | 3854 | |
bb70624e JA |
3855 | * Bourne Shell Variables:: Variables which Bash uses in the same way |
3856 | as the Bourne Shell. | |
3857 | * Bash Variables:: List of variables that exist in Bash. | |
ccc6cda3 | 3858 | |
bb70624e JA |
3859 | This chapter describes the shell variables that Bash uses. Bash |
3860 | automatically assigns default values to a number of variables. | |
cce855bc | 3861 | |
bb70624e JA |
3862 | \1f |
3863 | File: bashref.info, Node: Bourne Shell Variables, Next: Bash Variables, Up: Shell Variables | |
ccc6cda3 | 3864 | |
37c41ab1 CR |
3865 | 5.1 Bourne Shell Variables |
3866 | ========================== | |
cce855bc | 3867 | |
37c41ab1 CR |
3868 | Bash uses certain shell variables in the same way as the Bourne shell. |
3869 | In some cases, Bash assigns a default value to the variable. | |
cce855bc | 3870 | |
bb70624e JA |
3871 | `CDPATH' |
3872 | A colon-separated list of directories used as a search path for | |
3873 | the `cd' builtin command. | |
ccc6cda3 | 3874 | |
bb70624e JA |
3875 | `HOME' |
3876 | The current user's home directory; the default for the `cd' builtin | |
3877 | command. The value of this variable is also used by tilde | |
28ef6c31 | 3878 | expansion (*note Tilde Expansion::). |
ccc6cda3 | 3879 | |
bb70624e JA |
3880 | `IFS' |
3881 | A list of characters that separate fields; used when the shell | |
3882 | splits words as part of expansion. | |
ccc6cda3 | 3883 | |
bb70624e JA |
3884 | `MAIL' |
3885 | If this parameter is set to a filename and the `MAILPATH' variable | |
3886 | is not set, Bash informs the user of the arrival of mail in the | |
3887 | specified file. | |
cce855bc | 3888 | |
bb70624e JA |
3889 | `MAILPATH' |
3890 | A colon-separated list of filenames which the shell periodically | |
3891 | checks for new mail. Each list entry can specify the message that | |
3892 | is printed when new mail arrives in the mail file by separating | |
3893 | the file name from the message with a `?'. When used in the text | |
3894 | of the message, `$_' expands to the name of the current mail file. | |
cce855bc | 3895 | |
bb70624e JA |
3896 | `OPTARG' |
3897 | The value of the last option argument processed by the `getopts' | |
3898 | builtin. | |
ccc6cda3 | 3899 | |
bb70624e JA |
3900 | `OPTIND' |
3901 | The index of the last option argument processed by the `getopts' | |
3902 | builtin. | |
ccc6cda3 | 3903 | |
bb70624e JA |
3904 | `PATH' |
3905 | A colon-separated list of directories in which the shell looks for | |
d3a24ed2 CR |
3906 | commands. A zero-length (null) directory name in the value of |
3907 | `PATH' indicates the current directory. A null directory name may | |
3908 | appear as two adjacent colons, or as an initial or trailing colon. | |
ccc6cda3 | 3909 | |
bb70624e JA |
3910 | `PS1' |
3911 | The primary prompt string. The default value is `\s-\v\$ '. | |
3912 | *Note Printing a Prompt::, for the complete list of escape | |
3913 | sequences that are expanded before `PS1' is displayed. | |
ccc6cda3 | 3914 | |
bb70624e JA |
3915 | `PS2' |
3916 | The secondary prompt string. The default value is `> '. | |
ccc6cda3 | 3917 | |
761783bf | 3918 | |
bb70624e JA |
3919 | \1f |
3920 | File: bashref.info, Node: Bash Variables, Prev: Bourne Shell Variables, Up: Shell Variables | |
ccc6cda3 | 3921 | |
37c41ab1 CR |
3922 | 5.2 Bash Variables |
3923 | ================== | |
ccc6cda3 | 3924 | |
37c41ab1 | 3925 | These variables are set or used by Bash, but other shells do not |
bb70624e | 3926 | normally treat them specially. |
ccc6cda3 | 3927 | |
bb70624e JA |
3928 | A few variables used by Bash are described in different chapters: |
3929 | variables for controlling the job control facilities (*note Job Control | |
28ef6c31 | 3930 | Variables::). |
ccc6cda3 | 3931 | |
bb70624e JA |
3932 | `BASH' |
3933 | The full pathname used to execute the current instance of Bash. | |
ccc6cda3 | 3934 | |
d3ad40de CR |
3935 | `BASHPID' |
3936 | Expands to the process id of the current Bash process. This | |
3937 | differs from `$$' under certain circumstances, such as subshells | |
3938 | that do not require Bash to be re-initialized. | |
3939 | ||
d3a24ed2 CR |
3940 | `BASH_ARGC' |
3941 | An array variable whose values are the number of parameters in each | |
3942 | frame of the current bash execution call stack. The number of | |
3943 | parameters to the current subroutine (shell function or script | |
3944 | executed with `.' or `source') is at the top of the stack. When a | |
3945 | subroutine is executed, the number of parameters passed is pushed | |
9d2b70f0 | 3946 | onto `BASH_ARGC'. The shell sets `BASH_ARGC' only when in |
6a8fd0ed | 3947 | extended debugging mode (see *note The Shopt Builtin:: for a |
9d2b70f0 | 3948 | description of the `extdebug' option to the `shopt' builtin). |
d3a24ed2 CR |
3949 | |
3950 | `BASH_ARGV' | |
3951 | An array variable containing all of the parameters in the current | |
3952 | bash execution call stack. The final parameter of the last | |
3953 | subroutine call is at the top of the stack; the first parameter of | |
3954 | the initial call is at the bottom. When a subroutine is executed, | |
9d2b70f0 | 3955 | the parameters supplied are pushed onto `BASH_ARGV'. The shell |
6a8fd0ed | 3956 | sets `BASH_ARGV' only when in extended debugging mode (see *note |
d3ad40de CR |
3957 | The Shopt Builtin:: for a description of the `extdebug' option to |
3958 | the `shopt' builtin). | |
d3a24ed2 CR |
3959 | |
3960 | `BASH_COMMAND' | |
3961 | The command currently being executed or about to be executed, | |
3962 | unless the shell is executing a command as the result of a trap, | |
3963 | in which case it is the command executing at the time of the trap. | |
3964 | ||
bb70624e JA |
3965 | `BASH_ENV' |
3966 | If this variable is set when Bash is invoked to execute a shell | |
3967 | script, its value is expanded and used as the name of a startup | |
3968 | file to read before executing the script. *Note Bash Startup | |
3969 | Files::. | |
ccc6cda3 | 3970 | |
d3a24ed2 CR |
3971 | `BASH_EXECUTION_STRING' |
3972 | The command argument to the `-c' invocation option. | |
3973 | ||
3974 | `BASH_LINENO' | |
3975 | An array variable whose members are the line numbers in source | |
3976 | files corresponding to each member of FUNCNAME. | |
3977 | `${BASH_LINENO[$i]}' is the line number in the source file where | |
c2a47ea9 CR |
3978 | `${FUNCNAME[$i]}' was called (or `${BASH_LINENO[$i-1]}' if |
3979 | referenced within another shell function). The corresponding | |
3980 | source file name is `${BASH_SOURCE[$i]}'. Use `LINENO' to obtain | |
3981 | the current line number. | |
d3a24ed2 | 3982 | |
5e13499c CR |
3983 | `BASH_REMATCH' |
3984 | An array variable whose members are assigned by the `=~' binary | |
3985 | operator to the `[[' conditional command (*note Conditional | |
3986 | Constructs::). The element with index 0 is the portion of the | |
3987 | string matching the entire regular expression. The element with | |
3988 | index N is the portion of the string matching the Nth | |
3989 | parenthesized subexpression. This variable is read-only. | |
3990 | ||
d3a24ed2 CR |
3991 | `BASH_SOURCE' |
3992 | An array variable whose members are the source filenames | |
3993 | corresponding to the elements in the `FUNCNAME' array variable. | |
3994 | ||
3995 | `BASH_SUBSHELL' | |
3996 | Incremented by one each time a subshell or subshell environment is | |
3997 | spawned. The initial value is 0. | |
ccc6cda3 | 3998 | |
bb70624e | 3999 | `BASH_VERSINFO' |
28ef6c31 | 4000 | A readonly array variable (*note Arrays::) whose members hold |
bb70624e JA |
4001 | version information for this instance of Bash. The values |
4002 | assigned to the array members are as follows: | |
ccc6cda3 | 4003 | |
bb70624e JA |
4004 | `BASH_VERSINFO[0]' |
4005 | The major version number (the RELEASE). | |
ccc6cda3 | 4006 | |
bb70624e JA |
4007 | `BASH_VERSINFO[1]' |
4008 | The minor version number (the VERSION). | |
ccc6cda3 | 4009 | |
bb70624e JA |
4010 | `BASH_VERSINFO[2]' |
4011 | The patch level. | |
ccc6cda3 | 4012 | |
bb70624e JA |
4013 | `BASH_VERSINFO[3]' |
4014 | The build version. | |
ccc6cda3 | 4015 | |
bb70624e JA |
4016 | `BASH_VERSINFO[4]' |
4017 | The release status (e.g., BETA1). | |
ccc6cda3 | 4018 | |
bb70624e JA |
4019 | `BASH_VERSINFO[5]' |
4020 | The value of `MACHTYPE'. | |
ccc6cda3 | 4021 | |
761783bf | 4022 | |
d3a24ed2 CR |
4023 | `BASH_VERSION' |
4024 | The version number of the current instance of Bash. | |
4025 | ||
f73dda09 JA |
4026 | `COLUMNS' |
4027 | Used by the `select' builtin command to determine the terminal | |
4028 | width when printing selection lists. Automatically set upon | |
4029 | receipt of a `SIGWINCH'. | |
bb70624e JA |
4030 | |
4031 | `COMP_CWORD' | |
4032 | An index into `${COMP_WORDS}' of the word containing the current | |
4033 | cursor position. This variable is available only in shell | |
4034 | functions invoked by the programmable completion facilities (*note | |
28ef6c31 | 4035 | Programmable Completion::). |
bb70624e JA |
4036 | |
4037 | `COMP_LINE' | |
4038 | The current command line. This variable is available only in | |
4039 | shell functions and external commands invoked by the programmable | |
28ef6c31 | 4040 | completion facilities (*note Programmable Completion::). |
bb70624e JA |
4041 | |
4042 | `COMP_POINT' | |
4043 | The index of the current cursor position relative to the beginning | |
4044 | of the current command. If the current cursor position is at the | |
4045 | end of the current command, the value of this variable is equal to | |
4046 | `${#COMP_LINE}'. This variable is available only in shell | |
4047 | functions and external commands invoked by the programmable | |
28ef6c31 | 4048 | completion facilities (*note Programmable Completion::). |
bb70624e | 4049 | |
d3ad40de CR |
4050 | `COMP_TYPE' |
4051 | Set to an integer value corresponding to the type of completion | |
4052 | attempted that caused a completion function to be called: TAB, for | |
4053 | normal completion, `?', for listing completions after successive | |
4054 | tabs, `!', for listing alternatives on partial word completion, | |
4055 | `@', to list completions if the word is not unmodified, or `%', | |
4056 | for menu completion. This variable is available only in shell | |
4057 | functions and external commands invoked by the programmable | |
4058 | completion facilities (*note Programmable Completion::). | |
4059 | ||
4060 | `COMP_KEY' | |
4061 | The key (or final key of a key sequence) used to invoke the current | |
4062 | completion function. | |
4063 | ||
d3a24ed2 CR |
4064 | `COMP_WORDBREAKS' |
4065 | The set of characters that the Readline library treats as word | |
4066 | separators when performing word completion. If `COMP_WORDBREAKS' | |
4067 | is unset, it loses its special properties, even if it is | |
4068 | subsequently reset. | |
4069 | ||
f73dda09 JA |
4070 | `COMP_WORDS' |
4071 | An array variable consisting of the individual words in the | |
d3ad40de CR |
4072 | current command line. The words are split on shell metacharacters |
4073 | as the shell parser would separate them. This variable is | |
4074 | available only in shell functions invoked by the programmable | |
4075 | completion facilities (*note Programmable Completion::). | |
f73dda09 | 4076 | |
bb70624e JA |
4077 | `COMPREPLY' |
4078 | An array variable from which Bash reads the possible completions | |
4079 | generated by a shell function invoked by the programmable | |
28ef6c31 | 4080 | completion facility (*note Programmable Completion::). |
ccc6cda3 | 4081 | |
bb70624e JA |
4082 | `DIRSTACK' |
4083 | An array variable containing the current contents of the directory | |
4084 | stack. Directories appear in the stack in the order they are | |
4085 | displayed by the `dirs' builtin. Assigning to members of this | |
4086 | array variable may be used to modify directories already in the | |
4087 | stack, but the `pushd' and `popd' builtins must be used to add and | |
4088 | remove directories. Assignment to this variable will not change | |
4089 | the current directory. If `DIRSTACK' is unset, it loses its | |
4090 | special properties, even if it is subsequently reset. | |
cce855bc | 4091 | |
d3a24ed2 CR |
4092 | `EMACS' |
4093 | If Bash finds this variable in the environment when the shell | |
4094 | starts with value `t', it assumes that the shell is running in an | |
4095 | emacs shell buffer and disables line editing. | |
4096 | ||
bb70624e JA |
4097 | `EUID' |
4098 | The numeric effective user id of the current user. This variable | |
4099 | is readonly. | |
cce855bc | 4100 | |
bb70624e JA |
4101 | `FCEDIT' |
4102 | The editor used as a default by the `-e' option to the `fc' | |
4103 | builtin command. | |
ccc6cda3 | 4104 | |
bb70624e JA |
4105 | `FIGNORE' |
4106 | A colon-separated list of suffixes to ignore when performing | |
4107 | filename completion. A file name whose suffix matches one of the | |
4108 | entries in `FIGNORE' is excluded from the list of matched file | |
4109 | names. A sample value is `.o:~' | |
ccc6cda3 | 4110 | |
f73dda09 | 4111 | `FUNCNAME' |
d3a24ed2 CR |
4112 | An array variable containing the names of all shell functions |
4113 | currently in the execution call stack. The element with index 0 | |
4114 | is the name of any currently-executing shell function. The | |
d3ad40de | 4115 | bottom-most element is `"main"'. This variable exists only when a |
d3a24ed2 CR |
4116 | shell function is executing. Assignments to `FUNCNAME' have no |
4117 | effect and return an error status. If `FUNCNAME' is unset, it | |
4118 | loses its special properties, even if it is subsequently reset. | |
f73dda09 | 4119 | |
bb70624e JA |
4120 | `GLOBIGNORE' |
4121 | A colon-separated list of patterns defining the set of filenames to | |
4122 | be ignored by filename expansion. If a filename matched by a | |
4123 | filename expansion pattern also matches one of the patterns in | |
4124 | `GLOBIGNORE', it is removed from the list of matches. | |
ccc6cda3 | 4125 | |
bb70624e JA |
4126 | `GROUPS' |
4127 | An array variable containing the list of groups of which the | |
4128 | current user is a member. Assignments to `GROUPS' have no effect | |
28ef6c31 | 4129 | and return an error status. If `GROUPS' is unset, it loses its |
bb70624e | 4130 | special properties, even if it is subsequently reset. |
ccc6cda3 | 4131 | |
bb70624e JA |
4132 | `histchars' |
4133 | Up to three characters which control history expansion, quick | |
28ef6c31 JA |
4134 | substitution, and tokenization (*note History Interaction::). The |
4135 | first character is the HISTORY EXPANSION character, that is, the | |
4136 | character which signifies the start of a history expansion, | |
bb70624e JA |
4137 | normally `!'. The second character is the character which |
4138 | signifies `quick substitution' when seen as the first character on | |
4139 | a line, normally `^'. The optional third character is the | |
4140 | character which indicates that the remainder of the line is a | |
4141 | comment when found as the first character of a word, usually `#'. | |
4142 | The history comment character causes history substitution to be | |
4143 | skipped for the remaining words on the line. It does not | |
4144 | necessarily cause the shell parser to treat the rest of the line | |
4145 | as a comment. | |
cce855bc | 4146 | |
bb70624e JA |
4147 | `HISTCMD' |
4148 | The history number, or index in the history list, of the current | |
4149 | command. If `HISTCMD' is unset, it loses its special properties, | |
4150 | even if it is subsequently reset. | |
ccc6cda3 | 4151 | |
bb70624e | 4152 | `HISTCONTROL' |
d3a24ed2 CR |
4153 | A colon-separated list of values controlling how commands are |
4154 | saved on the history list. If the list of values includes | |
4155 | `ignorespace', lines which begin with a space character are not | |
4156 | saved in the history list. A value of `ignoredups' causes lines | |
4157 | which match the previous history entry to not be saved. A value | |
4158 | of `ignoreboth' is shorthand for `ignorespace' and `ignoredups'. | |
4159 | A value of `erasedups' causes all previous lines matching the | |
4160 | current line to be removed from the history list before that line | |
4161 | is saved. Any value not in the above list is ignored. If | |
4162 | `HISTCONTROL' is unset, or does not include a valid value, all | |
4163 | lines read by the shell parser are saved on the history list, | |
4164 | subject to the value of `HISTIGNORE'. The second and subsequent | |
4165 | lines of a multi-line compound command are not tested, and are | |
4166 | added to the history regardless of the value of `HISTCONTROL'. | |
ccc6cda3 | 4167 | |
f73dda09 JA |
4168 | `HISTFILE' |
4169 | The name of the file to which the command history is saved. The | |
4170 | default value is `~/.bash_history'. | |
4171 | ||
4172 | `HISTFILESIZE' | |
4173 | The maximum number of lines contained in the history file. When | |
4174 | this variable is assigned a value, the history file is truncated, | |
d3ad40de CR |
4175 | if necessary, by removing the oldest entries, to contain no more |
4176 | than that number of lines. The history file is also truncated to | |
4177 | this size after writing it when an interactive shell exits. The | |
4178 | default value is 500. | |
f73dda09 | 4179 | |
bb70624e JA |
4180 | `HISTIGNORE' |
4181 | A colon-separated list of patterns used to decide which command | |
4182 | lines should be saved on the history list. Each pattern is | |
4183 | anchored at the beginning of the line and must match the complete | |
4184 | line (no implicit `*' is appended). Each pattern is tested | |
4185 | against the line after the checks specified by `HISTCONTROL' are | |
4186 | applied. In addition to the normal shell pattern matching | |
4187 | characters, `&' matches the previous history line. `&' may be | |
4188 | escaped using a backslash; the backslash is removed before | |
4189 | attempting a match. The second and subsequent lines of a | |
4190 | multi-line compound command are not tested, and are added to the | |
4191 | history regardless of the value of `HISTIGNORE'. | |
cce855bc | 4192 | |
bb70624e JA |
4193 | `HISTIGNORE' subsumes the function of `HISTCONTROL'. A pattern of |
4194 | `&' is identical to `ignoredups', and a pattern of `[ ]*' is | |
4195 | identical to `ignorespace'. Combining these two patterns, | |
4196 | separating them with a colon, provides the functionality of | |
4197 | `ignoreboth'. | |
ccc6cda3 | 4198 | |
bb70624e JA |
4199 | `HISTSIZE' |
4200 | The maximum number of commands to remember on the history list. | |
4201 | The default value is 500. | |
b72432fd | 4202 | |
d3a24ed2 CR |
4203 | `HISTTIMEFORMAT' |
4204 | If this variable is set and not null, its value is used as a | |
4205 | format string for STRFTIME to print the time stamp associated with | |
4206 | each history entry displayed by the `history' builtin. If this | |
4207 | variable is set, time stamps are written to the history file so | |
d3ad40de CR |
4208 | they may be preserved across shell sessions. This uses the |
4209 | history comment character to distinguish timestamps from other | |
4210 | history lines. | |
d3a24ed2 | 4211 | |
bb70624e JA |
4212 | `HOSTFILE' |
4213 | Contains the name of a file in the same format as `/etc/hosts' that | |
4214 | should be read when the shell needs to complete a hostname. The | |
4215 | list of possible hostname completions may be changed while the | |
4216 | shell is running; the next time hostname completion is attempted | |
4217 | after the value is changed, Bash adds the contents of the new file | |
4218 | to the existing list. If `HOSTFILE' is set, but has no value, | |
4219 | Bash attempts to read `/etc/hosts' to obtain the list of possible | |
4220 | hostname completions. When `HOSTFILE' is unset, the hostname list | |
4221 | is cleared. | |
cce855bc | 4222 | |
bb70624e JA |
4223 | `HOSTNAME' |
4224 | The name of the current host. | |
cce855bc | 4225 | |
bb70624e JA |
4226 | `HOSTTYPE' |
4227 | A string describing the machine Bash is running on. | |
ccc6cda3 | 4228 | |
bb70624e JA |
4229 | `IGNOREEOF' |
4230 | Controls the action of the shell on receipt of an `EOF' character | |
4231 | as the sole input. If set, the value denotes the number of | |
4232 | consecutive `EOF' characters that can be read as the first | |
4233 | character on an input line before the shell will exit. If the | |
4234 | variable exists but does not have a numeric value (or has no | |
4235 | value) then the default is 10. If the variable does not exist, | |
4236 | then `EOF' signifies the end of input to the shell. This is only | |
4237 | in effect for interactive shells. | |
ccc6cda3 | 4238 | |
bb70624e JA |
4239 | `INPUTRC' |
4240 | The name of the Readline initialization file, overriding the | |
4241 | default of `~/.inputrc'. | |
ccc6cda3 | 4242 | |
bb70624e JA |
4243 | `LANG' |
4244 | Used to determine the locale category for any category not | |
4245 | specifically selected with a variable starting with `LC_'. | |
ccc6cda3 | 4246 | |
bb70624e JA |
4247 | `LC_ALL' |
4248 | This variable overrides the value of `LANG' and any other `LC_' | |
4249 | variable specifying a locale category. | |
cce855bc | 4250 | |
bb70624e JA |
4251 | `LC_COLLATE' |
4252 | This variable determines the collation order used when sorting the | |
4253 | results of filename expansion, and determines the behavior of | |
4254 | range expressions, equivalence classes, and collating sequences | |
4255 | within filename expansion and pattern matching (*note Filename | |
28ef6c31 | 4256 | Expansion::). |
ccc6cda3 | 4257 | |
bb70624e JA |
4258 | `LC_CTYPE' |
4259 | This variable determines the interpretation of characters and the | |
4260 | behavior of character classes within filename expansion and pattern | |
28ef6c31 | 4261 | matching (*note Filename Expansion::). |
ccc6cda3 | 4262 | |
bb70624e JA |
4263 | `LC_MESSAGES' |
4264 | This variable determines the locale used to translate double-quoted | |
28ef6c31 | 4265 | strings preceded by a `$' (*note Locale Translation::). |
ccc6cda3 | 4266 | |
bb70624e JA |
4267 | `LC_NUMERIC' |
4268 | This variable determines the locale category used for number | |
4269 | formatting. | |
ccc6cda3 | 4270 | |
f73dda09 JA |
4271 | `LINENO' |
4272 | The line number in the script or shell function currently | |
4273 | executing. | |
4274 | ||
28ef6c31 JA |
4275 | `LINES' |
4276 | Used by the `select' builtin command to determine the column length | |
4277 | for printing selection lists. Automatically set upon receipt of a | |
4278 | `SIGWINCH'. | |
4279 | ||
bb70624e JA |
4280 | `MACHTYPE' |
4281 | A string that fully describes the system type on which Bash is | |
4282 | executing, in the standard GNU CPU-COMPANY-SYSTEM format. | |
ccc6cda3 | 4283 | |
bb70624e JA |
4284 | `MAILCHECK' |
4285 | How often (in seconds) that the shell should check for mail in the | |
28ef6c31 JA |
4286 | files specified in the `MAILPATH' or `MAIL' variables. The |
4287 | default is 60 seconds. When it is time to check for mail, the | |
4288 | shell does so before displaying the primary prompt. If this | |
4289 | variable is unset, or set to a value that is not a number greater | |
4290 | than or equal to zero, the shell disables mail checking. | |
ccc6cda3 | 4291 | |
bb70624e JA |
4292 | `OLDPWD' |
4293 | The previous working directory as set by the `cd' builtin. | |
ccc6cda3 | 4294 | |
bb70624e JA |
4295 | `OPTERR' |
4296 | If set to the value 1, Bash displays error messages generated by | |
4297 | the `getopts' builtin command. | |
ccc6cda3 | 4298 | |
bb70624e JA |
4299 | `OSTYPE' |
4300 | A string describing the operating system Bash is running on. | |
ccc6cda3 | 4301 | |
bb70624e | 4302 | `PIPESTATUS' |
28ef6c31 | 4303 | An array variable (*note Arrays::) containing a list of exit |
bb70624e JA |
4304 | status values from the processes in the most-recently-executed |
4305 | foreground pipeline (which may contain only a single command). | |
ccc6cda3 | 4306 | |
f73dda09 JA |
4307 | `POSIXLY_CORRECT' |
4308 | If this variable is in the environment when `bash' starts, the | |
4309 | shell enters POSIX mode (*note Bash POSIX Mode::) before reading | |
4310 | the startup files, as if the `--posix' invocation option had been | |
4311 | supplied. If it is set while the shell is running, `bash' enables | |
4312 | POSIX mode, as if the command | |
4313 | `set -o posix' | |
f73dda09 JA |
4314 | had been executed. |
4315 | ||
bb70624e JA |
4316 | `PPID' |
4317 | The process ID of the shell's parent process. This variable is | |
4318 | readonly. | |
ccc6cda3 | 4319 | |
bb70624e JA |
4320 | `PROMPT_COMMAND' |
4321 | If set, the value is interpreted as a command to execute before | |
4322 | the printing of each primary prompt (`$PS1'). | |
ccc6cda3 | 4323 | |
bb70624e JA |
4324 | `PS3' |
4325 | The value of this variable is used as the prompt for the `select' | |
4326 | command. If this variable is not set, the `select' command | |
4327 | prompts with `#? ' | |
ccc6cda3 | 4328 | |
bb70624e JA |
4329 | `PS4' |
4330 | The value is the prompt printed before the command line is echoed | |
28ef6c31 | 4331 | when the `-x' option is set (*note The Set Builtin::). The first |
bb70624e JA |
4332 | character of `PS4' is replicated multiple times, as necessary, to |
4333 | indicate multiple levels of indirection. The default is `+ '. | |
ccc6cda3 | 4334 | |
bb70624e JA |
4335 | `PWD' |
4336 | The current working directory as set by the `cd' builtin. | |
ccc6cda3 | 4337 | |
bb70624e JA |
4338 | `RANDOM' |
4339 | Each time this parameter is referenced, a random integer between 0 | |
4340 | and 32767 is generated. Assigning a value to this variable seeds | |
4341 | the random number generator. | |
cce855bc | 4342 | |
bb70624e JA |
4343 | `REPLY' |
4344 | The default variable for the `read' builtin. | |
ccc6cda3 | 4345 | |
bb70624e JA |
4346 | `SECONDS' |
4347 | This variable expands to the number of seconds since the shell was | |
4348 | started. Assignment to this variable resets the count to the | |
4349 | value assigned, and the expanded value becomes the value assigned | |
4350 | plus the number of seconds since the assignment. | |
ccc6cda3 | 4351 | |
9f422431 CR |
4352 | `SHELL' |
4353 | The full pathname to the shell is kept in this environment | |
4354 | variable. If it is not set when the shell starts, Bash assigns to | |
4355 | it the full pathname of the current user's login shell. | |
4356 | ||
bb70624e JA |
4357 | `SHELLOPTS' |
4358 | A colon-separated list of enabled shell options. Each word in the | |
4359 | list is a valid argument for the `-o' option to the `set' builtin | |
28ef6c31 | 4360 | command (*note The Set Builtin::). The options appearing in |
bb70624e JA |
4361 | `SHELLOPTS' are those reported as `on' by `set -o'. If this |
4362 | variable is in the environment when Bash starts up, each shell | |
4363 | option in the list will be enabled before reading any startup | |
4364 | files. This variable is readonly. | |
ccc6cda3 | 4365 | |
bb70624e JA |
4366 | `SHLVL' |
4367 | Incremented by one each time a new instance of Bash is started. | |
4368 | This is intended to be a count of how deeply your Bash shells are | |
4369 | nested. | |
cce855bc | 4370 | |
bb70624e JA |
4371 | `TIMEFORMAT' |
4372 | The value of this parameter is used as a format string specifying | |
4373 | how the timing information for pipelines prefixed with the `time' | |
4374 | reserved word should be displayed. The `%' character introduces an | |
4375 | escape sequence that is expanded to a time value or other | |
4376 | information. The escape sequences and their meanings are as | |
4377 | follows; the braces denote optional portions. | |
cce855bc | 4378 | |
bb70624e JA |
4379 | `%%' |
4380 | A literal `%'. | |
ccc6cda3 | 4381 | |
bb70624e JA |
4382 | `%[P][l]R' |
4383 | The elapsed time in seconds. | |
ccc6cda3 | 4384 | |
bb70624e JA |
4385 | `%[P][l]U' |
4386 | The number of CPU seconds spent in user mode. | |
ccc6cda3 | 4387 | |
bb70624e JA |
4388 | `%[P][l]S' |
4389 | The number of CPU seconds spent in system mode. | |
ccc6cda3 | 4390 | |
bb70624e JA |
4391 | `%P' |
4392 | The CPU percentage, computed as (%U + %S) / %R. | |
ccc6cda3 | 4393 | |
bb70624e JA |
4394 | The optional P is a digit specifying the precision, the number of |
4395 | fractional digits after a decimal point. A value of 0 causes no | |
4396 | decimal point or fraction to be output. At most three places | |
4397 | after the decimal point may be specified; values of P greater than | |
4398 | 3 are changed to 3. If P is not specified, the value 3 is used. | |
ccc6cda3 | 4399 | |
bb70624e JA |
4400 | The optional `l' specifies a longer format, including minutes, of |
4401 | the form MMmSS.FFs. The value of P determines whether or not the | |
4402 | fraction is included. | |
ccc6cda3 | 4403 | |
bb70624e JA |
4404 | If this variable is not set, Bash acts as if it had the value |
4405 | `$'\nreal\t%3lR\nuser\t%3lU\nsys\t%3lS'' | |
4406 | If the value is null, no timing information is displayed. A | |
4407 | trailing newline is added when the format string is displayed. | |
ccc6cda3 | 4408 | |
bb70624e | 4409 | `TMOUT' |
7117c2d2 JA |
4410 | If set to a value greater than zero, `TMOUT' is treated as the |
4411 | default timeout for the `read' builtin (*note Bash Builtins::). | |
4412 | The `select' command (*note Conditional Constructs::) terminates | |
4413 | if input does not arrive after `TMOUT' seconds when input is coming | |
4414 | from a terminal. | |
4415 | ||
d3ad40de | 4416 | In an interactive shell, the value is interpreted as the number of |
7117c2d2 JA |
4417 | seconds to wait for input after issuing the primary prompt when |
4418 | the shell is interactive. Bash terminates after that number of | |
4419 | seconds if input does not arrive. | |
ccc6cda3 | 4420 | |
1c72c0cd CR |
4421 | `TMPDIR' |
4422 | If set, Bash uses its value as the name of a directory in which | |
4423 | Bash creates temporary files for the shell's use. | |
4424 | ||
bb70624e JA |
4425 | `UID' |
4426 | The numeric real user id of the current user. This variable is | |
4427 | readonly. | |
ccc6cda3 | 4428 | |
761783bf | 4429 | |
bb70624e JA |
4430 | \1f |
4431 | File: bashref.info, Node: Bash Features, Next: Job Control, Prev: Shell Variables, Up: Top | |
ccc6cda3 | 4432 | |
37c41ab1 CR |
4433 | 6 Bash Features |
4434 | *************** | |
ccc6cda3 | 4435 | |
37c41ab1 | 4436 | This section describes features unique to Bash. |
ccc6cda3 | 4437 | |
bb70624e | 4438 | * Menu: |
ccc6cda3 | 4439 | |
bb70624e JA |
4440 | * Invoking Bash:: Command line options that you can give |
4441 | to Bash. | |
4442 | * Bash Startup Files:: When and how Bash executes scripts. | |
4443 | * Interactive Shells:: What an interactive shell is. | |
4444 | * Bash Conditional Expressions:: Primitives used in composing expressions for | |
4445 | the `test' builtin. | |
4446 | * Shell Arithmetic:: Arithmetic on shell variables. | |
4447 | * Aliases:: Substituting one command for another. | |
4448 | * Arrays:: Array Variables. | |
4449 | * The Directory Stack:: History of visited directories. | |
4450 | * Printing a Prompt:: Controlling the PS1 string. | |
4451 | * The Restricted Shell:: A more controlled mode of shell execution. | |
4452 | * Bash POSIX Mode:: Making Bash behave more closely to what | |
4453 | the POSIX standard specifies. | |
ccc6cda3 | 4454 | |
bb70624e JA |
4455 | \1f |
4456 | File: bashref.info, Node: Invoking Bash, Next: Bash Startup Files, Up: Bash Features | |
ccc6cda3 | 4457 | |
37c41ab1 CR |
4458 | 6.1 Invoking Bash |
4459 | ================= | |
ccc6cda3 | 4460 | |
f73dda09 JA |
4461 | bash [long-opt] [-ir] [-abefhkmnptuvxdBCDHP] [-o OPTION] [-O SHOPT_OPTION] [ARGUMENT ...] |
4462 | bash [long-opt] [-abefhkmnptuvxdBCDHP] [-o OPTION] [-O SHOPT_OPTION] -c STRING [ARGUMENT ...] | |
4463 | bash [long-opt] -s [-abefhkmnptuvxdBCDHP] [-o OPTION] [-O SHOPT_OPTION] [ARGUMENT ...] | |
ccc6cda3 | 4464 | |
bb70624e | 4465 | In addition to the single-character shell command-line options |
28ef6c31 | 4466 | (*note The Set Builtin::), there are several multi-character options |
bb70624e | 4467 | that you can use. These options must appear on the command line before |
7117c2d2 | 4468 | the single-character options to be recognized. |
ccc6cda3 | 4469 | |
d3a24ed2 CR |
4470 | `--debugger' |
4471 | Arrange for the debugger profile to be executed before the shell | |
6a8fd0ed | 4472 | starts. Turns on extended debugging mode (see *note The Shopt |
d3ad40de | 4473 | Builtin:: for a description of the `extdebug' option to the `shopt' |
6a8fd0ed | 4474 | builtin) and shell function tracing (see *note The Set Builtin:: |
d3ad40de | 4475 | for a description of the `-o functrace' option). |
d3a24ed2 | 4476 | |
bb70624e JA |
4477 | `--dump-po-strings' |
4478 | A list of all double-quoted strings preceded by `$' is printed on | |
eb2bb562 | 4479 | the standard output in the GNU `gettext' PO (portable object) file |
bb70624e | 4480 | format. Equivalent to `-D' except for the output format. |
ccc6cda3 | 4481 | |
bb70624e JA |
4482 | `--dump-strings' |
4483 | Equivalent to `-D'. | |
ccc6cda3 | 4484 | |
bb70624e | 4485 | `--help' |
d3ad40de | 4486 | Display a usage message on standard output and exit successfully. |
ccc6cda3 | 4487 | |
28ef6c31 JA |
4488 | `--init-file FILENAME' |
4489 | `--rcfile FILENAME' | |
4490 | Execute commands from FILENAME (instead of `~/.bashrc') in an | |
4491 | interactive shell. | |
4492 | ||
bb70624e | 4493 | `--login' |
7117c2d2 | 4494 | Equivalent to `-l'. |
ccc6cda3 | 4495 | |
bb70624e | 4496 | `--noediting' |
28ef6c31 | 4497 | Do not use the GNU Readline library (*note Command Line Editing::) |
bb70624e | 4498 | to read command lines when the shell is interactive. |
ccc6cda3 | 4499 | |
bb70624e JA |
4500 | `--noprofile' |
4501 | Don't load the system-wide startup file `/etc/profile' or any of | |
4502 | the personal initialization files `~/.bash_profile', | |
4503 | `~/.bash_login', or `~/.profile' when Bash is invoked as a login | |
4504 | shell. | |
ccc6cda3 | 4505 | |
bb70624e JA |
4506 | `--norc' |
4507 | Don't read the `~/.bashrc' initialization file in an interactive | |
4508 | shell. This is on by default if the shell is invoked as `sh'. | |
ccc6cda3 | 4509 | |
bb70624e JA |
4510 | `--posix' |
4511 | Change the behavior of Bash where the default operation differs | |
ac18b312 CR |
4512 | from the POSIX standard to match the standard. This is intended |
4513 | to make Bash behave as a strict superset of that standard. *Note | |
4514 | Bash POSIX Mode::, for a description of the Bash POSIX mode. | |
ccc6cda3 | 4515 | |
bb70624e | 4516 | `--restricted' |
28ef6c31 | 4517 | Make the shell a restricted shell (*note The Restricted Shell::). |
ccc6cda3 | 4518 | |
bb70624e JA |
4519 | `--verbose' |
4520 | Equivalent to `-v'. Print shell input lines as they're read. | |
ccc6cda3 | 4521 | |
bb70624e JA |
4522 | `--version' |
4523 | Show version information for this instance of Bash on the standard | |
4524 | output and exit successfully. | |
ccc6cda3 | 4525 | |
761783bf | 4526 | |
bb70624e JA |
4527 | There are several single-character options that may be supplied at |
4528 | invocation which are not available with the `set' builtin. | |
ccc6cda3 | 4529 | |
bb70624e JA |
4530 | `-c STRING' |
4531 | Read and execute commands from STRING after processing the | |
4532 | options, then exit. Any remaining arguments are assigned to the | |
4533 | positional parameters, starting with `$0'. | |
ccc6cda3 | 4534 | |
bb70624e JA |
4535 | `-i' |
4536 | Force the shell to run interactively. Interactive shells are | |
6a8fd0ed | 4537 | described in *note Interactive Shells::. |
ccc6cda3 | 4538 | |
7117c2d2 JA |
4539 | `-l' |
4540 | Make this shell act as if it had been directly invoked by login. | |
4541 | When the shell is interactive, this is equivalent to starting a | |
4542 | login shell with `exec -l bash'. When the shell is not | |
4543 | interactive, the login shell startup files will be executed. | |
4544 | `exec bash -l' or `exec bash --login' will replace the current | |
4545 | shell with a Bash login shell. *Note Bash Startup Files::, for a | |
4546 | description of the special behavior of a login shell. | |
4547 | ||
bb70624e | 4548 | `-r' |
28ef6c31 | 4549 | Make the shell a restricted shell (*note The Restricted Shell::). |
ccc6cda3 | 4550 | |
bb70624e JA |
4551 | `-s' |
4552 | If this option is present, or if no arguments remain after option | |
4553 | processing, then commands are read from the standard input. This | |
4554 | option allows the positional parameters to be set when invoking an | |
4555 | interactive shell. | |
ccc6cda3 | 4556 | |
bb70624e JA |
4557 | `-D' |
4558 | A list of all double-quoted strings preceded by `$' is printed on | |
eb2bb562 | 4559 | the standard output. These are the strings that are subject to |
bb70624e | 4560 | language translation when the current locale is not `C' or `POSIX' |
28ef6c31 | 4561 | (*note Locale Translation::). This implies the `-n' option; no |
bb70624e | 4562 | commands will be executed. |
ccc6cda3 | 4563 | |
f73dda09 JA |
4564 | `[-+]O [SHOPT_OPTION]' |
4565 | SHOPT_OPTION is one of the shell options accepted by the `shopt' | |
d3ad40de CR |
4566 | builtin (*note The Shopt Builtin::). If SHOPT_OPTION is present, |
4567 | `-O' sets the value of that option; `+O' unsets it. If | |
f73dda09 JA |
4568 | SHOPT_OPTION is not supplied, the names and values of the shell |
4569 | options accepted by `shopt' are printed on the standard output. | |
4570 | If the invocation option is `+O', the output is displayed in a | |
4571 | format that may be reused as input. | |
4572 | ||
bb70624e JA |
4573 | `--' |
4574 | A `--' signals the end of options and disables further option | |
4575 | processing. Any arguments after the `--' are treated as filenames | |
4576 | and arguments. | |
ccc6cda3 | 4577 | |
761783bf | 4578 | |
f73dda09 JA |
4579 | A _login_ shell is one whose first character of argument zero is |
4580 | `-', or one invoked with the `--login' option. | |
4581 | ||
28ef6c31 | 4582 | An _interactive_ shell is one started without non-option arguments, |
bb70624e JA |
4583 | unless `-s' is specified, without specifying the `-c' option, and whose |
4584 | input and output are both connected to terminals (as determined by | |
4585 | `isatty(3)'), or one started with the `-i' option. *Note Interactive | |
28ef6c31 | 4586 | Shells::, for more information. |
ccc6cda3 | 4587 | |
bb70624e JA |
4588 | If arguments remain after option processing, and neither the `-c' |
4589 | nor the `-s' option has been supplied, the first argument is assumed to | |
28ef6c31 JA |
4590 | be the name of a file containing shell commands (*note Shell Scripts::). |
4591 | When Bash is invoked in this fashion, `$0' is set to the name of the | |
4592 | file, and the positional parameters are set to the remaining arguments. | |
4593 | Bash reads and executes commands from this file, then exits. Bash's | |
4594 | exit status is the exit status of the last command executed in the | |
4595 | script. If no commands are executed, the exit status is 0. | |
ccc6cda3 | 4596 | |
bb70624e JA |
4597 | \1f |
4598 | File: bashref.info, Node: Bash Startup Files, Next: Interactive Shells, Prev: Invoking Bash, Up: Bash Features | |
ccc6cda3 | 4599 | |
37c41ab1 CR |
4600 | 6.2 Bash Startup Files |
4601 | ====================== | |
ccc6cda3 | 4602 | |
d3ad40de | 4603 | This section describes how Bash executes its startup files. If any of |
37c41ab1 CR |
4604 | the files exist but cannot be read, Bash reports an error. Tildes are |
4605 | expanded in file names as described above under Tilde Expansion (*note | |
4606 | Tilde Expansion::). | |
ccc6cda3 | 4607 | |
6a8fd0ed | 4608 | Interactive shells are described in *note Interactive Shells::. |
ccc6cda3 | 4609 | |
bb70624e JA |
4610 | Invoked as an interactive login shell, or with `--login' |
4611 | ........................................................ | |
cce855bc | 4612 | |
37c41ab1 | 4613 | When Bash is invoked as an interactive login shell, or as a |
bb70624e JA |
4614 | non-interactive shell with the `--login' option, it first reads and |
4615 | executes commands from the file `/etc/profile', if that file exists. | |
4616 | After reading that file, it looks for `~/.bash_profile', | |
4617 | `~/.bash_login', and `~/.profile', in that order, and reads and | |
4618 | executes commands from the first one that exists and is readable. The | |
4619 | `--noprofile' option may be used when the shell is started to inhibit | |
4620 | this behavior. | |
ccc6cda3 | 4621 | |
bb70624e JA |
4622 | When a login shell exits, Bash reads and executes commands from the |
4623 | file `~/.bash_logout', if it exists. | |
ccc6cda3 | 4624 | |
bb70624e JA |
4625 | Invoked as an interactive non-login shell |
4626 | ......................................... | |
ccc6cda3 | 4627 | |
37c41ab1 | 4628 | When an interactive shell that is not a login shell is started, Bash |
bb70624e JA |
4629 | reads and executes commands from `~/.bashrc', if that file exists. |
4630 | This may be inhibited by using the `--norc' option. The `--rcfile | |
4631 | FILE' option will force Bash to read and execute commands from FILE | |
4632 | instead of `~/.bashrc'. | |
ccc6cda3 | 4633 | |
bb70624e JA |
4634 | So, typically, your `~/.bash_profile' contains the line |
4635 | `if [ -f ~/.bashrc ]; then . ~/.bashrc; fi' | |
37c41ab1 | 4636 | after (or before) any login-specific initializations. |
ccc6cda3 | 4637 | |
bb70624e JA |
4638 | Invoked non-interactively |
4639 | ......................... | |
ccc6cda3 | 4640 | |
37c41ab1 | 4641 | When Bash is started non-interactively, to run a shell script, for |
bb70624e JA |
4642 | example, it looks for the variable `BASH_ENV' in the environment, |
4643 | expands its value if it appears there, and uses the expanded value as | |
4644 | the name of a file to read and execute. Bash behaves as if the | |
4645 | following command were executed: | |
4646 | `if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi' | |
37c41ab1 CR |
4647 | but the value of the `PATH' variable is not used to search for the |
4648 | file name. | |
ccc6cda3 | 4649 | |
28ef6c31 JA |
4650 | As noted above, if a non-interactive shell is invoked with the |
4651 | `--login' option, Bash attempts to read and execute commands from the | |
4652 | login shell startup files. | |
4653 | ||
bb70624e JA |
4654 | Invoked with name `sh' |
4655 | ...................... | |
ccc6cda3 | 4656 | |
37c41ab1 | 4657 | If Bash is invoked with the name `sh', it tries to mimic the startup |
bb70624e JA |
4658 | behavior of historical versions of `sh' as closely as possible, while |
4659 | conforming to the POSIX standard as well. | |
ccc6cda3 | 4660 | |
bb70624e JA |
4661 | When invoked as an interactive login shell, or as a non-interactive |
4662 | shell with the `--login' option, it first attempts to read and execute | |
4663 | commands from `/etc/profile' and `~/.profile', in that order. The | |
4664 | `--noprofile' option may be used to inhibit this behavior. When | |
4665 | invoked as an interactive shell with the name `sh', Bash looks for the | |
4666 | variable `ENV', expands its value if it is defined, and uses the | |
4667 | expanded value as the name of a file to read and execute. Since a | |
4668 | shell invoked as `sh' does not attempt to read and execute commands | |
4669 | from any other startup files, the `--rcfile' option has no effect. A | |
4670 | non-interactive shell invoked with the name `sh' does not attempt to | |
4671 | read any other startup files. | |
ccc6cda3 | 4672 | |
bb70624e JA |
4673 | When invoked as `sh', Bash enters POSIX mode after the startup files |
4674 | are read. | |
b72432fd | 4675 | |
bb70624e JA |
4676 | Invoked in POSIX mode |
4677 | ..................... | |
ccc6cda3 | 4678 | |
37c41ab1 CR |
4679 | When Bash is started in POSIX mode, as with the `--posix' command line |
4680 | option, it follows the POSIX standard for startup files. In this mode, | |
4681 | interactive shells expand the `ENV' variable and commands are read and | |
4682 | executed from the file whose name is the expanded value. No other | |
4683 | startup files are read. | |
ccc6cda3 | 4684 | |
bb70624e JA |
4685 | Invoked by remote shell daemon |
4686 | .............................. | |
ccc6cda3 | 4687 | |
c2a47ea9 CR |
4688 | Bash attempts to determine when it is being run with its standard input |
4689 | connected to a a network connection, as if by the remote shell daemon, | |
4690 | usually `rshd', or the secure shell daemon `sshd'. If Bash determines | |
4691 | it is being run in this fashion, it reads and executes commands from | |
4692 | `~/.bashrc', if that file exists and is readable. It will not do this | |
4693 | if invoked as `sh'. The `--norc' option may be used to inhibit this | |
4694 | behavior, and the `--rcfile' option may be used to force another file | |
4695 | to be read, but `rshd' does not generally invoke the shell with those | |
4696 | options or allow them to be specified. | |
ccc6cda3 | 4697 | |
bb70624e JA |
4698 | Invoked with unequal effective and real UID/GIDs |
4699 | ................................................ | |
4700 | ||
37c41ab1 CR |
4701 | If Bash is started with the effective user (group) id not equal to the |
4702 | real user (group) id, and the `-p' option is not supplied, no startup | |
4703 | files are read, shell functions are not inherited from the environment, | |
4704 | the `SHELLOPTS' variable, if it appears in the environment, is ignored, | |
4705 | and the effective user id is set to the real user id. If the `-p' | |
4706 | option is supplied at invocation, the startup behavior is the same, but | |
4707 | the effective user id is not reset. | |
bb70624e JA |
4708 | |
4709 | \1f | |
4710 | File: bashref.info, Node: Interactive Shells, Next: Bash Conditional Expressions, Prev: Bash Startup Files, Up: Bash Features | |
4711 | ||
37c41ab1 CR |
4712 | 6.3 Interactive Shells |
4713 | ====================== | |
bb70624e JA |
4714 | |
4715 | * Menu: | |
4716 | ||
4717 | * What is an Interactive Shell?:: What determines whether a shell is Interactive. | |
4718 | * Is this Shell Interactive?:: How to tell if a shell is interactive. | |
4719 | * Interactive Shell Behavior:: What changes in a interactive shell? | |
4720 | ||
4721 | \1f | |
4722 | File: bashref.info, Node: What is an Interactive Shell?, Next: Is this Shell Interactive?, Up: Interactive Shells | |
4723 | ||
37c41ab1 CR |
4724 | 6.3.1 What is an Interactive Shell? |
4725 | ----------------------------------- | |
bb70624e | 4726 | |
37c41ab1 | 4727 | An interactive shell is one started without non-option arguments, |
d3ad40de CR |
4728 | unless `-s' is specified, without specifying the `-c' option, and whose |
4729 | input and error output are both connected to terminals (as determined | |
4730 | by `isatty(3)'), or one started with the `-i' option. | |
bb70624e JA |
4731 | |
4732 | An interactive shell generally reads from and writes to a user's | |
4733 | terminal. | |
4734 | ||
4735 | The `-s' invocation option may be used to set the positional | |
4736 | parameters when an interactive shell is started. | |
4737 | ||
4738 | \1f | |
4739 | File: bashref.info, Node: Is this Shell Interactive?, Next: Interactive Shell Behavior, Prev: What is an Interactive Shell?, Up: Interactive Shells | |
4740 | ||
37c41ab1 CR |
4741 | 6.3.2 Is this Shell Interactive? |
4742 | -------------------------------- | |
bb70624e | 4743 | |
37c41ab1 | 4744 | To determine within a startup script whether or not Bash is running |
bb70624e JA |
4745 | interactively, test the value of the `-' special parameter. It |
4746 | contains `i' when the shell is interactive. For example: | |
4747 | ||
4748 | case "$-" in | |
4749 | *i*) echo This shell is interactive ;; | |
4750 | *) echo This shell is not interactive ;; | |
4751 | esac | |
4752 | ||
28ef6c31 JA |
4753 | Alternatively, startup scripts may examine the variable `PS1'; it is |
4754 | unset in non-interactive shells, and set in interactive shells. Thus: | |
bb70624e JA |
4755 | |
4756 | if [ -z "$PS1" ]; then | |
4757 | echo This shell is not interactive | |
4758 | else | |
4759 | echo This shell is interactive | |
4760 | fi | |
4761 | ||
4762 | \1f | |
4763 | File: bashref.info, Node: Interactive Shell Behavior, Prev: Is this Shell Interactive?, Up: Interactive Shells | |
4764 | ||
37c41ab1 CR |
4765 | 6.3.3 Interactive Shell Behavior |
4766 | -------------------------------- | |
bb70624e | 4767 | |
37c41ab1 | 4768 | When the shell is running interactively, it changes its behavior in |
bb70624e JA |
4769 | several ways. |
4770 | ||
6a8fd0ed | 4771 | 1. Startup files are read and executed as described in *note Bash |
bb70624e JA |
4772 | Startup Files::. |
4773 | ||
28ef6c31 | 4774 | 2. Job Control (*note Job Control::) is enabled by default. When job |
bb70624e JA |
4775 | control is in effect, Bash ignores the keyboard-generated job |
4776 | control signals `SIGTTIN', `SIGTTOU', and `SIGTSTP'. | |
4777 | ||
28ef6c31 JA |
4778 | 3. Bash expands and displays `PS1' before reading the first line of a |
4779 | command, and expands and displays `PS2' before reading the second | |
4780 | and subsequent lines of a multi-line command. | |
bb70624e JA |
4781 | |
4782 | 4. Bash executes the value of the `PROMPT_COMMAND' variable as a | |
4783 | command before printing the primary prompt, `$PS1' (*note Bash | |
28ef6c31 | 4784 | Variables::). |
bb70624e | 4785 | |
28ef6c31 | 4786 | 5. Readline (*note Command Line Editing::) is used to read commands |
bb70624e JA |
4787 | from the user's terminal. |
4788 | ||
4789 | 6. Bash inspects the value of the `ignoreeof' option to `set -o' | |
4790 | instead of exiting immediately when it receives an `EOF' on its | |
28ef6c31 | 4791 | standard input when reading a command (*note The Set Builtin::). |
bb70624e | 4792 | |
28ef6c31 JA |
4793 | 7. Command history (*note Bash History Facilities::) and history |
4794 | expansion (*note History Interaction::) are enabled by default. | |
bb70624e JA |
4795 | Bash will save the command history to the file named by `$HISTFILE' |
4796 | when an interactive shell exits. | |
4797 | ||
28ef6c31 | 4798 | 8. Alias expansion (*note Aliases::) is performed by default. |
bb70624e JA |
4799 | |
4800 | 9. In the absence of any traps, Bash ignores `SIGTERM' (*note | |
28ef6c31 | 4801 | Signals::). |
bb70624e JA |
4802 | |
4803 | 10. In the absence of any traps, `SIGINT' is caught and handled | |
28ef6c31 | 4804 | ((*note Signals::). `SIGINT' will interrupt some shell builtins. |
bb70624e JA |
4805 | |
4806 | 11. An interactive login shell sends a `SIGHUP' to all jobs on exit if | |
d3ad40de | 4807 | the `huponexit' shell option has been enabled (*note Signals::). |
bb70624e JA |
4808 | |
4809 | 12. The `-n' invocation option is ignored, and `set -n' has no effect | |
28ef6c31 | 4810 | (*note The Set Builtin::). |
bb70624e JA |
4811 | |
4812 | 13. Bash will check for mail periodically, depending on the values of | |
4813 | the `MAIL', `MAILPATH', and `MAILCHECK' shell variables (*note | |
28ef6c31 | 4814 | Bash Variables::). |
bb70624e JA |
4815 | |
4816 | 14. Expansion errors due to references to unbound shell variables after | |
4817 | `set -u' has been enabled will not cause the shell to exit (*note | |
28ef6c31 | 4818 | The Set Builtin::). |
bb70624e JA |
4819 | |
4820 | 15. The shell will not exit on expansion errors caused by VAR being | |
4821 | unset or null in `${VAR:?WORD}' expansions (*note Shell Parameter | |
28ef6c31 | 4822 | Expansion::). |
bb70624e JA |
4823 | |
4824 | 16. Redirection errors encountered by shell builtins will not cause the | |
4825 | shell to exit. | |
4826 | ||
4827 | 17. When running in POSIX mode, a special builtin returning an error | |
28ef6c31 | 4828 | status will not cause the shell to exit (*note Bash POSIX Mode::). |
bb70624e JA |
4829 | |
4830 | 18. A failed `exec' will not cause the shell to exit (*note Bourne | |
28ef6c31 | 4831 | Shell Builtins::). |
bb70624e JA |
4832 | |
4833 | 19. Parser syntax errors will not cause the shell to exit. | |
4834 | ||
4835 | 20. Simple spelling correction for directory arguments to the `cd' | |
4836 | builtin is enabled by default (see the description of the `cdspell' | |
6a8fd0ed | 4837 | option to the `shopt' builtin in *note The Shopt Builtin::). |
bb70624e JA |
4838 | |
4839 | 21. The shell will check the value of the `TMOUT' variable and exit if | |
4840 | a command is not read within the specified number of seconds after | |
28ef6c31 | 4841 | printing `$PS1' (*note Bash Variables::). |
bb70624e JA |
4842 | |
4843 | ||
4844 | \1f | |
4845 | File: bashref.info, Node: Bash Conditional Expressions, Next: Shell Arithmetic, Prev: Interactive Shells, Up: Bash Features | |
4846 | ||
37c41ab1 CR |
4847 | 6.4 Bash Conditional Expressions |
4848 | ================================ | |
bb70624e | 4849 | |
37c41ab1 CR |
4850 | Conditional expressions are used by the `[[' compound command and the |
4851 | `test' and `[' builtin commands. | |
bb70624e JA |
4852 | |
4853 | Expressions may be unary or binary. Unary expressions are often | |
4854 | used to examine the status of a file. There are string operators and | |
4855 | numeric comparison operators as well. If the FILE argument to one of | |
4856 | the primaries is of the form `/dev/fd/N', then file descriptor N is | |
4857 | checked. If the FILE argument to one of the primaries is one of | |
4858 | `/dev/stdin', `/dev/stdout', or `/dev/stderr', file descriptor 0, 1, or | |
4859 | 2, respectively, is checked. | |
4860 | ||
37c41ab1 CR |
4861 | Unless otherwise specified, primaries that operate on files follow |
4862 | symbolic links and operate on the target of the link, rather than the | |
4863 | link itself. | |
4864 | ||
bb70624e JA |
4865 | `-a FILE' |
4866 | True if FILE exists. | |
4867 | ||
4868 | `-b FILE' | |
4869 | True if FILE exists and is a block special file. | |
4870 | ||
4871 | `-c FILE' | |
4872 | True if FILE exists and is a character special file. | |
4873 | ||
4874 | `-d FILE' | |
4875 | True if FILE exists and is a directory. | |
4876 | ||
4877 | `-e FILE' | |
4878 | True if FILE exists. | |
4879 | ||
4880 | `-f FILE' | |
4881 | True if FILE exists and is a regular file. | |
4882 | ||
4883 | `-g FILE' | |
4884 | True if FILE exists and its set-group-id bit is set. | |
4885 | ||
4886 | `-h FILE' | |
4887 | True if FILE exists and is a symbolic link. | |
4888 | ||
4889 | `-k FILE' | |
4890 | True if FILE exists and its "sticky" bit is set. | |
4891 | ||
4892 | `-p FILE' | |
4893 | True if FILE exists and is a named pipe (FIFO). | |
4894 | ||
4895 | `-r FILE' | |
4896 | True if FILE exists and is readable. | |
4897 | ||
4898 | `-s FILE' | |
4899 | True if FILE exists and has a size greater than zero. | |
4900 | ||
4901 | `-t FD' | |
4902 | True if file descriptor FD is open and refers to a terminal. | |
ccc6cda3 JA |
4903 | |
4904 | `-u FILE' | |
4905 | True if FILE exists and its set-user-id bit is set. | |
4906 | ||
4907 | `-w FILE' | |
4908 | True if FILE exists and is writable. | |
4909 | ||
4910 | `-x FILE' | |
4911 | True if FILE exists and is executable. | |
4912 | ||
4913 | `-O FILE' | |
4914 | True if FILE exists and is owned by the effective user id. | |
4915 | ||
4916 | `-G FILE' | |
4917 | True if FILE exists and is owned by the effective group id. | |
4918 | ||
cce855bc JA |
4919 | `-L FILE' |
4920 | True if FILE exists and is a symbolic link. | |
4921 | ||
4922 | `-S FILE' | |
4923 | True if FILE exists and is a socket. | |
4924 | ||
4925 | `-N FILE' | |
4926 | True if FILE exists and has been modified since it was last read. | |
4927 | ||
ccc6cda3 | 4928 | `FILE1 -nt FILE2' |
7117c2d2 JA |
4929 | True if FILE1 is newer (according to modification date) than |
4930 | FILE2, or if FILE1 exists and FILE2 does not. | |
ccc6cda3 JA |
4931 | |
4932 | `FILE1 -ot FILE2' | |
7117c2d2 JA |
4933 | True if FILE1 is older than FILE2, or if FILE2 exists and FILE1 |
4934 | does not. | |
ccc6cda3 JA |
4935 | |
4936 | `FILE1 -ef FILE2' | |
7117c2d2 | 4937 | True if FILE1 and FILE2 refer to the same device and inode numbers. |
ccc6cda3 JA |
4938 | |
4939 | `-o OPTNAME' | |
4940 | True if shell option OPTNAME is enabled. The list of options | |
4941 | appears in the description of the `-o' option to the `set' builtin | |
28ef6c31 | 4942 | (*note The Set Builtin::). |
ccc6cda3 JA |
4943 | |
4944 | `-z STRING' | |
4945 | True if the length of STRING is zero. | |
4946 | ||
4947 | `-n STRING' | |
4948 | `STRING' | |
4949 | True if the length of STRING is non-zero. | |
4950 | ||
cce855bc | 4951 | `STRING1 == STRING2' |
7117c2d2 JA |
4952 | True if the strings are equal. `=' may be used in place of `==' |
4953 | for strict POSIX compliance. | |
ccc6cda3 JA |
4954 | |
4955 | `STRING1 != STRING2' | |
4956 | True if the strings are not equal. | |
4957 | ||
4958 | `STRING1 < STRING2' | |
cce855bc JA |
4959 | True if STRING1 sorts before STRING2 lexicographically in the |
4960 | current locale. | |
ccc6cda3 JA |
4961 | |
4962 | `STRING1 > STRING2' | |
cce855bc JA |
4963 | True if STRING1 sorts after STRING2 lexicographically in the |
4964 | current locale. | |
ccc6cda3 JA |
4965 | |
4966 | `ARG1 OP ARG2' | |
4967 | `OP' is one of `-eq', `-ne', `-lt', `-le', `-gt', or `-ge'. These | |
4968 | arithmetic binary operators return true if ARG1 is equal to, not | |
4969 | equal to, less than, less than or equal to, greater than, or | |
4970 | greater than or equal to ARG2, respectively. ARG1 and ARG2 may be | |
4971 | positive or negative integers. | |
4972 | ||
761783bf | 4973 | |
ccc6cda3 | 4974 | \1f |
bb70624e | 4975 | File: bashref.info, Node: Shell Arithmetic, Next: Aliases, Prev: Bash Conditional Expressions, Up: Bash Features |
ccc6cda3 | 4976 | |
37c41ab1 CR |
4977 | 6.5 Shell Arithmetic |
4978 | ==================== | |
ccc6cda3 | 4979 | |
37c41ab1 CR |
4980 | The shell allows arithmetic expressions to be evaluated, as one of the |
4981 | shell expansions or by the `let' and the `-i' option to the `declare' | |
4982 | builtins. | |
ccc6cda3 | 4983 | |
7117c2d2 JA |
4984 | Evaluation is done in fixed-width integers with no check for |
4985 | overflow, though division by 0 is trapped and flagged as an error. The | |
d3a24ed2 CR |
4986 | operators and their precedence, associativity, and values are the same |
4987 | as in the C language. The following list of operators is grouped into | |
4988 | levels of equal-precedence operators. The levels are listed in order | |
4989 | of decreasing precedence. | |
cce855bc | 4990 | |
bb70624e JA |
4991 | `ID++ ID--' |
4992 | variable post-increment and post-decrement | |
d166f048 | 4993 | |
bb70624e JA |
4994 | `++ID --ID' |
4995 | variable pre-increment and pre-decrement | |
ccc6cda3 | 4996 | |
bb70624e JA |
4997 | `- +' |
4998 | unary minus and plus | |
ccc6cda3 | 4999 | |
bb70624e JA |
5000 | `! ~' |
5001 | logical and bitwise negation | |
ccc6cda3 | 5002 | |
bb70624e JA |
5003 | `**' |
5004 | exponentiation | |
ccc6cda3 | 5005 | |
bb70624e JA |
5006 | `* / %' |
5007 | multiplication, division, remainder | |
ccc6cda3 | 5008 | |
bb70624e JA |
5009 | `+ -' |
5010 | addition, subtraction | |
ccc6cda3 | 5011 | |
bb70624e JA |
5012 | `<< >>' |
5013 | left and right bitwise shifts | |
cce855bc | 5014 | |
bb70624e JA |
5015 | `<= >= < >' |
5016 | comparison | |
cce855bc | 5017 | |
bb70624e JA |
5018 | `== !=' |
5019 | equality and inequality | |
cce855bc | 5020 | |
bb70624e JA |
5021 | `&' |
5022 | bitwise AND | |
cce855bc | 5023 | |
bb70624e JA |
5024 | `^' |
5025 | bitwise exclusive OR | |
cce855bc | 5026 | |
bb70624e JA |
5027 | `|' |
5028 | bitwise OR | |
cce855bc | 5029 | |
bb70624e JA |
5030 | `&&' |
5031 | logical AND | |
ccc6cda3 | 5032 | |
bb70624e JA |
5033 | `||' |
5034 | logical OR | |
ccc6cda3 | 5035 | |
bb70624e | 5036 | `expr ? expr : expr' |
d3a24ed2 | 5037 | conditional operator |
cce855bc | 5038 | |
bb70624e JA |
5039 | `= *= /= %= += -= <<= >>= &= ^= |=' |
5040 | assignment | |
ccc6cda3 | 5041 | |
bb70624e JA |
5042 | `expr1 , expr2' |
5043 | comma | |
ccc6cda3 | 5044 | |
bb70624e JA |
5045 | Shell variables are allowed as operands; parameter expansion is |
5046 | performed before the expression is evaluated. Within an expression, | |
5047 | shell variables may also be referenced by name without using the | |
d3a24ed2 CR |
5048 | parameter expansion syntax. A shell variable that is null or unset |
5049 | evaluates to 0 when referenced by name without using the parameter | |
5050 | expansion syntax. The value of a variable is evaluated as an | |
5051 | arithmetic expression when it is referenced, or when a variable which | |
5052 | has been given the INTEGER attribute using `declare -i' is assigned a | |
5053 | value. A null value evaluates to 0. A shell variable need not have | |
5054 | its integer attribute turned on to be used in an expression. | |
ccc6cda3 | 5055 | |
bb70624e JA |
5056 | Constants with a leading 0 are interpreted as octal numbers. A |
5057 | leading `0x' or `0X' denotes hexadecimal. Otherwise, numbers take the | |
5058 | form [BASE`#']N, where BASE is a decimal number between 2 and 64 | |
5059 | representing the arithmetic base, and N is a number in that base. If | |
5060 | BASE`#' is omitted, then base 10 is used. The digits greater than 9 | |
f73dda09 JA |
5061 | are represented by the lowercase letters, the uppercase letters, `@', |
5062 | and `_', in that order. If BASE is less than or equal to 36, lowercase | |
eb2bb562 | 5063 | and uppercase letters may be used interchangeably to represent numbers |
bb70624e | 5064 | between 10 and 35. |
ccc6cda3 | 5065 | |
bb70624e JA |
5066 | Operators are evaluated in order of precedence. Sub-expressions in |
5067 | parentheses are evaluated first and may override the precedence rules | |
5068 | above. | |
ccc6cda3 | 5069 | |
bb70624e JA |
5070 | \1f |
5071 | File: bashref.info, Node: Aliases, Next: Arrays, Prev: Shell Arithmetic, Up: Bash Features | |
ccc6cda3 | 5072 | |
37c41ab1 CR |
5073 | 6.6 Aliases |
5074 | =========== | |
ccc6cda3 | 5075 | |
37c41ab1 CR |
5076 | ALIASES allow a string to be substituted for a word when it is used as |
5077 | the first word of a simple command. The shell maintains a list of | |
bb70624e | 5078 | aliases that may be set and unset with the `alias' and `unalias' |
cce855bc JA |
5079 | builtin commands. |
5080 | ||
5081 | The first word of each simple command, if unquoted, is checked to see | |
5082 | if it has an alias. If so, that word is replaced by the text of the | |
de8913bd CR |
5083 | alias. The characters `/', `$', ``', `=' and any of the shell |
5084 | metacharacters or quoting characters listed above may not appear in an | |
5085 | alias name. The replacement text may contain any valid shell input, | |
5086 | including shell metacharacters. The first word of the replacement text | |
5087 | is tested for aliases, but a word that is identical to an alias being | |
5088 | expanded is not expanded a second time. This means that one may alias | |
5089 | `ls' to `"ls -F"', for instance, and Bash does not try to recursively | |
5090 | expand the replacement text. If the last character of the alias value | |
5091 | is a space or tab character, then the next command word following the | |
5092 | alias is also checked for alias expansion. | |
cce855bc JA |
5093 | |
5094 | Aliases are created and listed with the `alias' command, and removed | |
5095 | with the `unalias' command. | |
5096 | ||
5097 | There is no mechanism for using arguments in the replacement text, | |
5098 | as in `csh'. If arguments are needed, a shell function should be used | |
28ef6c31 | 5099 | (*note Shell Functions::). |
cce855bc JA |
5100 | |
5101 | Aliases are not expanded when the shell is not interactive, unless | |
d3ad40de CR |
5102 | the `expand_aliases' shell option is set using `shopt' (*note The Shopt |
5103 | Builtin::). | |
ccc6cda3 | 5104 | |
cce855bc JA |
5105 | The rules concerning the definition and use of aliases are somewhat |
5106 | confusing. Bash always reads at least one complete line of input | |
5107 | before executing any of the commands on that line. Aliases are | |
5108 | expanded when a command is read, not when it is executed. Therefore, an | |
5109 | alias definition appearing on the same line as another command does not | |
5110 | take effect until the next line of input is read. The commands | |
5111 | following the alias definition on that line are not affected by the new | |
5112 | alias. This behavior is also an issue when functions are executed. | |
5113 | Aliases are expanded when a function definition is read, not when the | |
5114 | function is executed, because a function definition is itself a | |
5115 | compound command. As a consequence, aliases defined in a function are | |
5116 | not available until after that function is executed. To be safe, | |
5117 | always put alias definitions on a separate line, and do not use `alias' | |
5118 | in compound commands. | |
ccc6cda3 | 5119 | |
bb70624e | 5120 | For almost every purpose, shell functions are preferred over aliases. |
ccc6cda3 JA |
5121 | |
5122 | \1f | |
cce855bc | 5123 | File: bashref.info, Node: Arrays, Next: The Directory Stack, Prev: Aliases, Up: Bash Features |
ccc6cda3 | 5124 | |
37c41ab1 CR |
5125 | 6.7 Arrays |
5126 | ========== | |
ccc6cda3 | 5127 | |
37c41ab1 | 5128 | Bash provides one-dimensional array variables. Any variable may be |
ccc6cda3 JA |
5129 | used as an array; the `declare' builtin will explicitly declare an |
5130 | array. There is no maximum limit on the size of an array, nor any | |
5131 | requirement that members be indexed or assigned contiguously. Arrays | |
5132 | are zero-based. | |
5133 | ||
5134 | An array is created automatically if any variable is assigned to | |
5135 | using the syntax | |
5136 | name[SUBSCRIPT]=VALUE | |
5137 | ||
5138 | The SUBSCRIPT is treated as an arithmetic expression that must evaluate | |
5139 | to a number greater than or equal to zero. To explicitly declare an | |
5140 | array, use | |
5141 | declare -a NAME | |
37c41ab1 | 5142 | The syntax |
ccc6cda3 | 5143 | declare -a NAME[SUBSCRIPT] |
37c41ab1 | 5144 | is also accepted; the SUBSCRIPT is ignored. Attributes may be |
ccc6cda3 JA |
5145 | specified for an array variable using the `declare' and `readonly' |
5146 | builtins. Each attribute applies to all members of an array. | |
5147 | ||
5148 | Arrays are assigned to using compound assignments of the form | |
5149 | name=(value1 ... valueN) | |
37c41ab1 | 5150 | where each VALUE is of the form `[[SUBSCRIPT]=]'STRING. If the |
ccc6cda3 JA |
5151 | optional subscript is supplied, that index is assigned to; otherwise |
5152 | the index of the element assigned is the last index assigned to by the | |
5153 | statement plus one. Indexing starts at zero. This syntax is also | |
5154 | accepted by the `declare' builtin. Individual array elements may be | |
5155 | assigned to using the `name['SUBSCRIPT`]='VALUE syntax introduced above. | |
5156 | ||
5157 | Any element of an array may be referenced using | |
5158 | `${name['SUBSCRIPT`]}'. The braces are required to avoid conflicts | |
5159 | with the shell's filename expansion operators. If the SUBSCRIPT is `@' | |
5160 | or `*', the word expands to all members of the array NAME. These | |
5161 | subscripts differ only when the word appears within double quotes. If | |
5162 | the word is double-quoted, `${name[*]}' expands to a single word with | |
5163 | the value of each array member separated by the first character of the | |
5164 | `IFS' variable, and `${name[@]}' expands each element of NAME to a | |
5165 | separate word. When there are no array members, `${name[@]}' expands | |
37c41ab1 CR |
5166 | to nothing. If the double-quoted expansion occurs within a word, the |
5167 | expansion of the first parameter is joined with the beginning part of | |
5168 | the original word, and the expansion of the last parameter is joined | |
5169 | with the last part of the original word. This is analogous to the | |
5170 | expansion of the special parameters `@' and `*'. | |
5171 | `${#name['SUBSCRIPT`]}' expands to the length of `${name['SUBSCRIPT`]}'. | |
5172 | If SUBSCRIPT is `@' or `*', the expansion is the number of elements in | |
5173 | the array. Referencing an array variable without a subscript is | |
5174 | equivalent to referencing element zero. | |
ccc6cda3 JA |
5175 | |
5176 | The `unset' builtin is used to destroy arrays. `unset' | |
1c72c0cd CR |
5177 | NAME[SUBSCRIPT] destroys the array element at index SUBSCRIPT. Care |
5178 | must be taken to avoid unwanted side effects caused by filename | |
5179 | generation. `unset' NAME, where NAME is an array, removes the entire | |
5180 | array. A subscript of `*' or `@' also removes the entire array. | |
ccc6cda3 JA |
5181 | |
5182 | The `declare', `local', and `readonly' builtins each accept a `-a' | |
5183 | option to specify an array. The `read' builtin accepts a `-a' option | |
5184 | to assign a list of words read from the standard input to an array, and | |
5185 | can read values from the standard input into individual array elements. | |
5186 | The `set' and `declare' builtins display array values in a way that | |
5187 | allows them to be reused as input. | |
5188 | ||
5189 | \1f | |
cce855bc JA |
5190 | File: bashref.info, Node: The Directory Stack, Next: Printing a Prompt, Prev: Arrays, Up: Bash Features |
5191 | ||
37c41ab1 CR |
5192 | 6.8 The Directory Stack |
5193 | ======================= | |
cce855bc | 5194 | |
bb70624e JA |
5195 | * Menu: |
5196 | ||
5197 | * Directory Stack Builtins:: Bash builtin commands to manipulate | |
5198 | the directory stack. | |
5199 | ||
5200 | The directory stack is a list of recently-visited directories. The | |
cce855bc JA |
5201 | `pushd' builtin adds directories to the stack as it changes the current |
5202 | directory, and the `popd' builtin removes specified directories from | |
5203 | the stack and changes the current directory to the directory removed. | |
5204 | The `dirs' builtin displays the contents of the directory stack. | |
5205 | ||
5206 | The contents of the directory stack are also visible as the value of | |
5207 | the `DIRSTACK' shell variable. | |
5208 | ||
bb70624e JA |
5209 | \1f |
5210 | File: bashref.info, Node: Directory Stack Builtins, Up: The Directory Stack | |
5211 | ||
37c41ab1 CR |
5212 | 6.8.1 Directory Stack Builtins |
5213 | ------------------------------ | |
bb70624e | 5214 | |
cce855bc | 5215 | `dirs' |
bb70624e | 5216 | dirs [+N | -N] [-clpv] |
cce855bc JA |
5217 | Display the list of currently remembered directories. Directories |
5218 | are added to the list with the `pushd' command; the `popd' command | |
5219 | removes directories from the list. | |
5220 | `+N' | |
5221 | Displays the Nth directory (counting from the left of the | |
5222 | list printed by `dirs' when invoked without options), starting | |
5223 | with zero. | |
5224 | ||
5225 | `-N' | |
5226 | Displays the Nth directory (counting from the right of the | |
5227 | list printed by `dirs' when invoked without options), starting | |
5228 | with zero. | |
5229 | ||
5230 | `-c' | |
5231 | Clears the directory stack by deleting all of the elements. | |
5232 | ||
5233 | `-l' | |
5234 | Produces a longer listing; the default listing format uses a | |
5235 | tilde to denote the home directory. | |
5236 | ||
5237 | `-p' | |
5238 | Causes `dirs' to print the directory stack with one entry per | |
5239 | line. | |
5240 | ||
5241 | `-v' | |
5242 | Causes `dirs' to print the directory stack with one entry per | |
5243 | line, prefixing each entry with its index in the stack. | |
5244 | ||
5245 | `popd' | |
5246 | popd [+N | -N] [-n] | |
5247 | ||
5248 | Remove the top entry from the directory stack, and `cd' to the new | |
5249 | top directory. When no arguments are given, `popd' removes the | |
5250 | top directory from the stack and performs a `cd' to the new top | |
5251 | directory. The elements are numbered from 0 starting at the first | |
5252 | directory listed with `dirs'; i.e., `popd' is equivalent to `popd | |
5253 | +0'. | |
5254 | `+N' | |
5255 | Removes the Nth directory (counting from the left of the list | |
5256 | printed by `dirs'), starting with zero. | |
5257 | ||
5258 | `-N' | |
5259 | Removes the Nth directory (counting from the right of the | |
5260 | list printed by `dirs'), starting with zero. | |
5261 | ||
5262 | `-n' | |
5263 | Suppresses the normal change of directory when removing | |
5264 | directories from the stack, so that only the stack is | |
5265 | manipulated. | |
5266 | ||
5267 | `pushd' | |
d3ad40de | 5268 | pushd [-n] [+N | -N | DIR ] |
cce855bc JA |
5269 | |
5270 | Save the current directory on the top of the directory stack and | |
5271 | then `cd' to DIR. With no arguments, `pushd' exchanges the top | |
5272 | two directories. | |
5273 | ||
d3ad40de CR |
5274 | `-n' |
5275 | Suppresses the normal change of directory when adding | |
5276 | directories to the stack, so that only the stack is | |
5277 | manipulated. | |
5278 | ||
cce855bc JA |
5279 | `+N' |
5280 | Brings the Nth directory (counting from the left of the list | |
5281 | printed by `dirs', starting with zero) to the top of the list | |
5282 | by rotating the stack. | |
5283 | ||
5284 | `-N' | |
5285 | Brings the Nth directory (counting from the right of the list | |
5286 | printed by `dirs', starting with zero) to the top of the list | |
5287 | by rotating the stack. | |
5288 | ||
cce855bc JA |
5289 | `DIR' |
5290 | Makes the current working directory be the top of the stack, | |
5291 | and then executes the equivalent of ``cd' DIR'. `cd's to DIR. | |
5292 | ||
761783bf | 5293 | |
cce855bc JA |
5294 | \1f |
5295 | File: bashref.info, Node: Printing a Prompt, Next: The Restricted Shell, Prev: The Directory Stack, Up: Bash Features | |
ccc6cda3 | 5296 | |
37c41ab1 CR |
5297 | 6.9 Controlling the Prompt |
5298 | ========================== | |
ccc6cda3 | 5299 | |
37c41ab1 CR |
5300 | The value of the variable `PROMPT_COMMAND' is examined just before Bash |
5301 | prints each primary prompt. If `PROMPT_COMMAND' is set and has a | |
bb70624e JA |
5302 | non-null value, then the value is executed just as if it had been typed |
5303 | on the command line. | |
ccc6cda3 JA |
5304 | |
5305 | In addition, the following table describes the special characters | |
5306 | which can appear in the prompt variables: | |
5307 | ||
5308 | `\a' | |
cce855bc | 5309 | A bell character. |
ccc6cda3 JA |
5310 | |
5311 | `\d' | |
cce855bc | 5312 | The date, in "Weekday Month Date" format (e.g., "Tue May 26"). |
ccc6cda3 | 5313 | |
7117c2d2 JA |
5314 | `\D{FORMAT}' |
5315 | The FORMAT is passed to `strftime'(3) and the result is inserted | |
5316 | into the prompt string; an empty FORMAT results in a | |
5317 | locale-specific time representation. The braces are required. | |
5318 | ||
ccc6cda3 | 5319 | `\e' |
cce855bc | 5320 | An escape character. |
ccc6cda3 JA |
5321 | |
5322 | `\h' | |
cce855bc | 5323 | The hostname, up to the first `.'. |
ccc6cda3 JA |
5324 | |
5325 | `\H' | |
cce855bc | 5326 | The hostname. |
ccc6cda3 | 5327 | |
bb70624e JA |
5328 | `\j' |
5329 | The number of jobs currently managed by the shell. | |
5330 | ||
5331 | `\l' | |
5332 | The basename of the shell's terminal device name. | |
5333 | ||
ccc6cda3 | 5334 | `\n' |
cce855bc JA |
5335 | A newline. |
5336 | ||
5337 | `\r' | |
5338 | A carriage return. | |
ccc6cda3 JA |
5339 | |
5340 | `\s' | |
cce855bc | 5341 | The name of the shell, the basename of `$0' (the portion following |
ccc6cda3 JA |
5342 | the final slash). |
5343 | ||
5344 | `\t' | |
cce855bc | 5345 | The time, in 24-hour HH:MM:SS format. |
ccc6cda3 JA |
5346 | |
5347 | `\T' | |
cce855bc | 5348 | The time, in 12-hour HH:MM:SS format. |
ccc6cda3 JA |
5349 | |
5350 | `\@' | |
cce855bc JA |
5351 | The time, in 12-hour am/pm format. |
5352 | ||
f73dda09 JA |
5353 | `\A' |
5354 | The time, in 24-hour HH:MM format. | |
5355 | ||
cce855bc JA |
5356 | `\u' |
5357 | The username of the current user. | |
ccc6cda3 JA |
5358 | |
5359 | `\v' | |
cce855bc | 5360 | The version of Bash (e.g., 2.00) |
ccc6cda3 JA |
5361 | |
5362 | `\V' | |
cce855bc | 5363 | The release of Bash, version + patchlevel (e.g., 2.00.0) |
ccc6cda3 JA |
5364 | |
5365 | `\w' | |
12d937f9 CR |
5366 | The current working directory, with `$HOME' abbreviated with a |
5367 | tilde. | |
ccc6cda3 JA |
5368 | |
5369 | `\W' | |
12d937f9 | 5370 | The basename of `$PWD', with `$HOME' abbreviated with a tilde. |
ccc6cda3 JA |
5371 | |
5372 | `\!' | |
cce855bc | 5373 | The history number of this command. |
ccc6cda3 JA |
5374 | |
5375 | `\#' | |
cce855bc | 5376 | The command number of this command. |
ccc6cda3 JA |
5377 | |
5378 | `\$' | |
cce855bc | 5379 | If the effective uid is 0, `#', otherwise `$'. |
ccc6cda3 | 5380 | |
cce855bc JA |
5381 | `\NNN' |
5382 | The character whose ASCII code is the octal value NNN. | |
ccc6cda3 JA |
5383 | |
5384 | `\\' | |
cce855bc | 5385 | A backslash. |
ccc6cda3 JA |
5386 | |
5387 | `\[' | |
cce855bc | 5388 | Begin a sequence of non-printing characters. This could be used to |
ccc6cda3 JA |
5389 | embed a terminal control sequence into the prompt. |
5390 | ||
5391 | `\]' | |
cce855bc | 5392 | End a sequence of non-printing characters. |
ccc6cda3 | 5393 | |
bb70624e JA |
5394 | The command number and the history number are usually different: the |
5395 | history number of a command is its position in the history list, which | |
5396 | may include commands restored from the history file (*note Bash History | |
28ef6c31 JA |
5397 | Facilities::), while the command number is the position in the sequence |
5398 | of commands executed during the current shell session. | |
bb70624e JA |
5399 | |
5400 | After the string is decoded, it is expanded via parameter expansion, | |
5401 | command substitution, arithmetic expansion, and quote removal, subject | |
28ef6c31 | 5402 | to the value of the `promptvars' shell option (*note Bash Builtins::). |
bb70624e | 5403 | |
ccc6cda3 JA |
5404 | \1f |
5405 | File: bashref.info, Node: The Restricted Shell, Next: Bash POSIX Mode, Prev: Printing a Prompt, Up: Bash Features | |
5406 | ||
37c41ab1 CR |
5407 | 6.10 The Restricted Shell |
5408 | ========================= | |
ccc6cda3 | 5409 | |
37c41ab1 CR |
5410 | If Bash is started with the name `rbash', or the `--restricted' or `-r' |
5411 | option is supplied at invocation, the shell becomes restricted. A | |
ccc6cda3 JA |
5412 | restricted shell is used to set up an environment more controlled than |
5413 | the standard shell. A restricted shell behaves identically to `bash' | |
7117c2d2 JA |
5414 | with the exception that the following are disallowed or not performed: |
5415 | ||
ccc6cda3 JA |
5416 | * Changing directories with the `cd' builtin. |
5417 | ||
b72432fd JA |
5418 | * Setting or unsetting the values of the `SHELL', `PATH', `ENV', or |
5419 | `BASH_ENV' variables. | |
ccc6cda3 JA |
5420 | |
5421 | * Specifying command names containing slashes. | |
5422 | ||
5423 | * Specifying a filename containing a slash as an argument to the `.' | |
5424 | builtin command. | |
5425 | ||
bb70624e JA |
5426 | * Specifying a filename containing a slash as an argument to the `-p' |
5427 | option to the `hash' builtin command. | |
5428 | ||
ccc6cda3 JA |
5429 | * Importing function definitions from the shell environment at |
5430 | startup. | |
5431 | ||
cce855bc JA |
5432 | * Parsing the value of `SHELLOPTS' from the shell environment at |
5433 | startup. | |
5434 | ||
ccc6cda3 JA |
5435 | * Redirecting output using the `>', `>|', `<>', `>&', `&>', and `>>' |
5436 | redirection operators. | |
5437 | ||
5438 | * Using the `exec' builtin to replace the shell with another command. | |
5439 | ||
5440 | * Adding or deleting builtin commands with the `-f' and `-d' options | |
5441 | to the `enable' builtin. | |
5442 | ||
7117c2d2 JA |
5443 | * Using the `enable' builtin command to enable disabled shell |
5444 | builtins. | |
5445 | ||
ccc6cda3 JA |
5446 | * Specifying the `-p' option to the `command' builtin. |
5447 | ||
cce855bc | 5448 | * Turning off restricted mode with `set +r' or `set +o restricted'. |
ccc6cda3 | 5449 | |
7117c2d2 JA |
5450 | These restrictions are enforced after any startup files are read. |
5451 | ||
5452 | When a command that is found to be a shell script is executed (*note | |
5453 | Shell Scripts::), `rbash' turns off any restrictions in the shell | |
5454 | spawned to execute the script. | |
5455 | ||
ccc6cda3 JA |
5456 | \1f |
5457 | File: bashref.info, Node: Bash POSIX Mode, Prev: The Restricted Shell, Up: Bash Features | |
5458 | ||
37c41ab1 CR |
5459 | 6.11 Bash POSIX Mode |
5460 | ==================== | |
ccc6cda3 | 5461 | |
37c41ab1 CR |
5462 | Starting Bash with the `--posix' command-line option or executing `set |
5463 | -o posix' while Bash is running will cause Bash to conform more closely | |
ac18b312 CR |
5464 | to the POSIX standard by changing the behavior to match that specified |
5465 | by POSIX in areas where the Bash default differs. | |
ccc6cda3 | 5466 | |
7117c2d2 JA |
5467 | When invoked as `sh', Bash enters POSIX mode after reading the |
5468 | startup files. | |
5469 | ||
ccc6cda3 JA |
5470 | The following list is what's changed when `POSIX mode' is in effect: |
5471 | ||
5472 | 1. When a command in the hash table no longer exists, Bash will | |
5473 | re-search `$PATH' to find the new location. This is also | |
5474 | available with `shopt -s checkhash'. | |
5475 | ||
28ef6c31 JA |
5476 | 2. The message printed by the job control code and builtins when a job |
5477 | exits with a non-zero status is `Done(status)'. | |
ccc6cda3 JA |
5478 | |
5479 | 3. The message printed by the job control code and builtins when a job | |
28ef6c31 JA |
5480 | is stopped is `Stopped(SIGNAME)', where SIGNAME is, for example, |
5481 | `SIGTSTP'. | |
ccc6cda3 | 5482 | |
1c72c0cd CR |
5483 | 4. The `bg' builtin uses the required format to describe each job |
5484 | placed in the background, which does not include an indication of | |
5485 | whether the job is the current or previous job. | |
5486 | ||
5487 | 5. Reserved words appearing in a context where reserved words are | |
3ee6b87d | 5488 | recognized do not undergo alias expansion. |
ccc6cda3 | 5489 | |
ac18b312 CR |
5490 | 6. The POSIX `PS1' and `PS2' expansions of `!' to the history number |
5491 | and `!!' to `!' are enabled, and parameter expansion is performed | |
5492 | on the values of `PS1' and `PS2' regardless of the setting of the | |
5493 | `promptvars' option. | |
ccc6cda3 | 5494 | |
ac18b312 CR |
5495 | 7. The POSIX startup files are executed (`$ENV') rather than the |
5496 | normal Bash files. | |
ccc6cda3 | 5497 | |
1c72c0cd | 5498 | 8. Tilde expansion is only performed on assignments preceding a |
ccc6cda3 JA |
5499 | command name, rather than on all assignment statements on the line. |
5500 | ||
1c72c0cd | 5501 | 9. The default history file is `~/.sh_history' (this is the default |
ccc6cda3 JA |
5502 | value of `$HISTFILE'). |
5503 | ||
1c72c0cd | 5504 | 10. The output of `kill -l' prints all the signal names on a single |
d3a24ed2 CR |
5505 | line, separated by spaces, without the `SIG' prefix. |
5506 | ||
1c72c0cd | 5507 | 11. The `kill' builtin does not accept signal names with a `SIG' |
d3a24ed2 | 5508 | prefix. |
ccc6cda3 | 5509 | |
1c72c0cd | 5510 | 12. Non-interactive shells exit if FILENAME in `.' FILENAME is not |
ccc6cda3 JA |
5511 | found. |
5512 | ||
1c72c0cd | 5513 | 13. Non-interactive shells exit if a syntax error in an arithmetic |
cce855bc JA |
5514 | expansion results in an invalid expression. |
5515 | ||
1c72c0cd | 5516 | 14. Redirection operators do not perform filename expansion on the word |
ccc6cda3 JA |
5517 | in the redirection unless the shell is interactive. |
5518 | ||
1c72c0cd | 5519 | 15. Redirection operators do not perform word splitting on the word in |
bb70624e JA |
5520 | the redirection. |
5521 | ||
1c72c0cd | 5522 | 16. Function names must be valid shell `name's. That is, they may not |
ccc6cda3 | 5523 | contain characters other than letters, digits, and underscores, and |
cce855bc | 5524 | may not start with a digit. Declaring a function with an invalid |
ccc6cda3 JA |
5525 | name causes a fatal syntax error in non-interactive shells. |
5526 | ||
ac18b312 CR |
5527 | 17. POSIX special builtins are found before shell functions during |
5528 | command lookup. | |
ccc6cda3 | 5529 | |
ac18b312 | 5530 | 18. If a POSIX special builtin returns an error status, a |
ccc6cda3 | 5531 | non-interactive shell exits. The fatal errors are those listed in |
ac18b312 | 5532 | the POSIX standard, and include things like passing incorrect |
ccc6cda3 JA |
5533 | options, redirection errors, variable assignment errors for |
5534 | assignments preceding the command name, and so on. | |
5535 | ||
1c72c0cd | 5536 | 19. If `CDPATH' is set, the `cd' builtin will not implicitly append |
cce855bc JA |
5537 | the current directory to it. This means that `cd' will fail if no |
5538 | valid directory name can be constructed from any of the entries in | |
5539 | `$CDPATH', even if the a directory with the same name as the name | |
5540 | given as an argument to `cd' exists in the current directory. | |
5541 | ||
1c72c0cd | 5542 | 20. A non-interactive shell exits with an error status if a variable |
ccc6cda3 JA |
5543 | assignment error occurs when no command name follows the assignment |
5544 | statements. A variable assignment error occurs, for example, when | |
cce855bc | 5545 | trying to assign a value to a readonly variable. |
ccc6cda3 | 5546 | |
1c72c0cd | 5547 | 21. A non-interactive shell exits with an error status if the iteration |
ccc6cda3 | 5548 | variable in a `for' statement or the selection variable in a |
cce855bc | 5549 | `select' statement is a readonly variable. |
ccc6cda3 | 5550 | |
1c72c0cd | 5551 | 22. Process substitution is not available. |
ccc6cda3 | 5552 | |
ac18b312 CR |
5553 | 23. Assignment statements preceding POSIX special builtins persist in |
5554 | the shell environment after the builtin completes. | |
ccc6cda3 | 5555 | |
1c72c0cd | 5556 | 24. Assignment statements preceding shell function calls persist in the |
28ef6c31 JA |
5557 | shell environment after the function returns, as if a POSIX |
5558 | special builtin command had been executed. | |
5559 | ||
1c72c0cd | 5560 | 25. The `export' and `readonly' builtin commands display their output |
ac18b312 | 5561 | in the format required by POSIX. |
d166f048 | 5562 | |
1c72c0cd | 5563 | 26. The `trap' builtin displays signal names without the leading `SIG'. |
28ef6c31 | 5564 | |
1c72c0cd | 5565 | 27. The `trap' builtin doesn't check the first argument for a possible |
d3a24ed2 | 5566 | signal specification and revert the signal handling to the original |
8a9c66f6 CR |
5567 | disposition if it is, unless that argument consists solely of |
5568 | digits and is a valid signal number. If users want to reset the | |
5569 | handler for a given signal to the original disposition, they | |
5570 | should use `-' as the first argument. | |
d3a24ed2 | 5571 | |
1c72c0cd | 5572 | 28. The `.' and `source' builtins do not search the current directory |
28ef6c31 JA |
5573 | for the filename argument if it is not found by searching `PATH'. |
5574 | ||
1c72c0cd | 5575 | 29. Subshells spawned to execute command substitutions inherit the |
28ef6c31 JA |
5576 | value of the `-e' option from the parent shell. When not in POSIX |
5577 | mode, Bash clears the `-e' option in such subshells. | |
5578 | ||
1c72c0cd | 5579 | 30. Alias expansion is always enabled, even in non-interactive shells. |
28ef6c31 | 5580 | |
1c72c0cd | 5581 | 31. When the `alias' builtin displays alias definitions, it does not |
d3a24ed2 CR |
5582 | display them with a leading `alias ' unless the `-p' option is |
5583 | supplied. | |
5584 | ||
1c72c0cd | 5585 | 32. When the `set' builtin is invoked without options, it does not |
28ef6c31 JA |
5586 | display shell function names and definitions. |
5587 | ||
1c72c0cd | 5588 | 33. When the `set' builtin is invoked without options, it displays |
f73dda09 JA |
5589 | variable values without quotes, unless they contain shell |
5590 | metacharacters, even if the result contains nonprinting characters. | |
ccc6cda3 | 5591 | |
1c72c0cd | 5592 | 34. When the `cd' builtin is invoked in LOGICAL mode, and the pathname |
7117c2d2 JA |
5593 | constructed from `$PWD' and the directory name supplied as an |
5594 | argument does not refer to an existing directory, `cd' will fail | |
5595 | instead of falling back to PHYSICAL mode. | |
5596 | ||
1c72c0cd | 5597 | 35. When the `pwd' builtin is supplied the `-P' option, it resets |
9d2b70f0 CR |
5598 | `$PWD' to a pathname containing no symlinks. |
5599 | ||
1c72c0cd CR |
5600 | 36. The `pwd' builtin verifies that the value it prints is the same as |
5601 | the current directory, even if it is not asked to check the file | |
5602 | system with the `-P' option. | |
5603 | ||
5604 | 37. When listing the history, the `fc' builtin does not include an | |
8a9c66f6 CR |
5605 | indication of whether or not a history entry has been modified. |
5606 | ||
1c72c0cd | 5607 | 38. The default editor used by `fc' is `ed'. |
8a9c66f6 | 5608 | |
1c72c0cd | 5609 | 39. The `type' and `command' builtins will not report a non-executable |
37c41ab1 CR |
5610 | file as having been found, though the shell will attempt to |
5611 | execute such a file if it is the only so-named file found in | |
5612 | `$PATH'. | |
5613 | ||
1c72c0cd CR |
5614 | 40. The `vi' editing mode will invoke the `vi' editor directly when |
5615 | the `v' command is run, instead of checking `$FCEDIT' and | |
5616 | `$EDITOR'. | |
5617 | ||
5618 | 41. When the `xpg_echo' option is enabled, Bash does not attempt to | |
37c41ab1 CR |
5619 | interpret any arguments to `echo' as options. Each argument is |
5620 | displayed, after escape characters are converted. | |
5621 | ||
8a9c66f6 | 5622 | |
ac18b312 | 5623 | There is other POSIX behavior that Bash does not implement by |
1c72c0cd | 5624 | default even when in POSIX mode. Specifically: |
ccc6cda3 | 5625 | |
1c72c0cd CR |
5626 | 1. The `fc' builtin checks `$EDITOR' as a program to edit history |
5627 | entries if `FCEDIT' is unset, rather than defaulting directly to | |
5628 | `ed'. `fc' uses `ed' if `EDITOR' is unset. | |
ccc6cda3 | 5629 | |
1c72c0cd CR |
5630 | 2. As noted above, Bash requires the `xpg_echo' option to be enabled |
5631 | for the `echo' builtin to be fully conformant. | |
28ef6c31 | 5632 | |
28ef6c31 | 5633 | |
1c72c0cd CR |
5634 | Bash can be configured to be POSIX-conformant by default, by |
5635 | specifying the `--enable-strict-posix-default' to `configure' when | |
5636 | building (*note Optional Features::). | |
28ef6c31 | 5637 | |
ccc6cda3 | 5638 | \1f |
c2a47ea9 | 5639 | File: bashref.info, Node: Job Control, Next: Command Line Editing, Prev: Bash Features, Up: Top |
ccc6cda3 | 5640 | |
37c41ab1 CR |
5641 | 7 Job Control |
5642 | ************* | |
ccc6cda3 | 5643 | |
37c41ab1 CR |
5644 | This chapter discusses what job control is, how it works, and how Bash |
5645 | allows you to access its facilities. | |
ccc6cda3 JA |
5646 | |
5647 | * Menu: | |
5648 | ||
5649 | * Job Control Basics:: How job control works. | |
5650 | * Job Control Builtins:: Bash builtin commands used to interact | |
5651 | with job control. | |
5652 | * Job Control Variables:: Variables Bash uses to customize job | |
5653 | control. | |
5654 | ||
5655 | \1f | |
5656 | File: bashref.info, Node: Job Control Basics, Next: Job Control Builtins, Up: Job Control | |
5657 | ||
37c41ab1 CR |
5658 | 7.1 Job Control Basics |
5659 | ====================== | |
ccc6cda3 | 5660 | |
37c41ab1 | 5661 | Job control refers to the ability to selectively stop (suspend) the |
ccc6cda3 JA |
5662 | execution of processes and continue (resume) their execution at a later |
5663 | point. A user typically employs this facility via an interactive | |
5664 | interface supplied jointly by the system's terminal driver and Bash. | |
5665 | ||
5666 | The shell associates a JOB with each pipeline. It keeps a table of | |
5667 | currently executing jobs, which may be listed with the `jobs' command. | |
cce855bc | 5668 | When Bash starts a job asynchronously, it prints a line that looks like: |
ccc6cda3 | 5669 | [1] 25647 |
37c41ab1 CR |
5670 | indicating that this job is job number 1 and that the process ID of |
5671 | the last process in the pipeline associated with this job is 25647. | |
5672 | All of the processes in a single pipeline are members of the same job. | |
5673 | Bash uses the JOB abstraction as the basis for job control. | |
ccc6cda3 JA |
5674 | |
5675 | To facilitate the implementation of the user interface to job | |
bb70624e JA |
5676 | control, the operating system maintains the notion of a current terminal |
5677 | process group ID. Members of this process group (processes whose | |
5678 | process group ID is equal to the current terminal process group ID) | |
5679 | receive keyboard-generated signals such as `SIGINT'. These processes | |
5680 | are said to be in the foreground. Background processes are those whose | |
5681 | process group ID differs from the terminal's; such processes are immune | |
5682 | to keyboard-generated signals. Only foreground processes are allowed | |
5683 | to read from or write to the terminal. Background processes which | |
5684 | attempt to read from (write to) the terminal are sent a `SIGTTIN' | |
5685 | (`SIGTTOU') signal by the terminal driver, which, unless caught, | |
5686 | suspends the process. | |
ccc6cda3 JA |
5687 | |
5688 | If the operating system on which Bash is running supports job | |
cce855bc JA |
5689 | control, Bash contains facilities to use it. Typing the SUSPEND |
5690 | character (typically `^Z', Control-Z) while a process is running causes | |
5691 | that process to be stopped and returns control to Bash. Typing the | |
5692 | DELAYED SUSPEND character (typically `^Y', Control-Y) causes the | |
5693 | process to be stopped when it attempts to read input from the terminal, | |
5694 | and control to be returned to Bash. The user then manipulates the | |
5695 | state of this job, using the `bg' command to continue it in the | |
5696 | background, the `fg' command to continue it in the foreground, or the | |
5697 | `kill' command to kill it. A `^Z' takes effect immediately, and has | |
5698 | the additional side effect of causing pending output and typeahead to | |
5699 | be discarded. | |
ccc6cda3 JA |
5700 | |
5701 | There are a number of ways to refer to a job in the shell. The | |
bb70624e JA |
5702 | character `%' introduces a job name. |
5703 | ||
5704 | Job number `n' may be referred to as `%n'. The symbols `%%' and | |
5705 | `%+' refer to the shell's notion of the current job, which is the last | |
eb2bb562 CR |
5706 | job stopped while it was in the foreground or started in the background. |
5707 | A single `%' (with no accompanying job specification) also refers to | |
5708 | the current job. The previous job may be referenced using `%-'. In | |
5709 | output pertaining to jobs (e.g., the output of the `jobs' command), the | |
bb70624e JA |
5710 | current job is always flagged with a `+', and the previous job with a |
5711 | `-'. | |
5712 | ||
5713 | A job may also be referred to using a prefix of the name used to | |
5714 | start it, or using a substring that appears in its command line. For | |
5715 | example, `%ce' refers to a stopped `ce' job. Using `%?ce', on the other | |
5716 | hand, refers to any job containing the string `ce' in its command line. | |
5717 | If the prefix or substring matches more than one job, Bash reports an | |
5718 | error. | |
ccc6cda3 JA |
5719 | |
5720 | Simply naming a job can be used to bring it into the foreground: | |
5721 | `%1' is a synonym for `fg %1', bringing job 1 from the background into | |
5722 | the foreground. Similarly, `%1 &' resumes job 1 in the background, | |
5723 | equivalent to `bg %1' | |
5724 | ||
5725 | The shell learns immediately whenever a job changes state. | |
5726 | Normally, Bash waits until it is about to print a prompt before | |
5727 | reporting changes in a job's status so as to not interrupt any other | |
f73dda09 JA |
5728 | output. If the `-b' option to the `set' builtin is enabled, Bash |
5729 | reports such changes immediately (*note The Set Builtin::). Any trap | |
5730 | on `SIGCHLD' is executed for each child process that exits. | |
ccc6cda3 | 5731 | |
d3ad40de | 5732 | If an attempt to exit Bash is made while jobs are stopped, (or |
6a8fd0ed | 5733 | running, if the `checkjobs' option is enabled - see *note The Shopt |
d3ad40de CR |
5734 | Builtin::), the shell prints a warning message, and if the `checkjobs' |
5735 | option is enabled, lists the jobs and their statuses. The `jobs' | |
cce855bc JA |
5736 | command may then be used to inspect their status. If a second attempt |
5737 | to exit is made without an intervening command, Bash does not print | |
d3ad40de | 5738 | another warning, and any stopped jobs are terminated. |
ccc6cda3 JA |
5739 | |
5740 | \1f | |
5741 | File: bashref.info, Node: Job Control Builtins, Next: Job Control Variables, Prev: Job Control Basics, Up: Job Control | |
5742 | ||
37c41ab1 CR |
5743 | 7.2 Job Control Builtins |
5744 | ======================== | |
ccc6cda3 JA |
5745 | |
5746 | `bg' | |
37c41ab1 CR |
5747 | bg [JOBSPEC ...] |
5748 | Resume each suspended job JOBSPEC in the background, as if it had | |
cce855bc JA |
5749 | been started with `&'. If JOBSPEC is not supplied, the current |
5750 | job is used. The return status is zero unless it is run when job | |
1c72c0cd CR |
5751 | control is not enabled, or, when run with job control enabled, any |
5752 | JOBSPEC was not found or specifies a job that was started without | |
5753 | job control. | |
ccc6cda3 JA |
5754 | |
5755 | `fg' | |
5756 | fg [JOBSPEC] | |
cce855bc JA |
5757 | Resume the job JOBSPEC in the foreground and make it the current |
5758 | job. If JOBSPEC is not supplied, the current job is used. The | |
5759 | return status is that of the command placed into the foreground, | |
5760 | or non-zero if run when job control is disabled or, when run with | |
5761 | job control enabled, JOBSPEC does not specify a valid job or | |
5762 | JOBSPEC specifies a job that was started without job control. | |
ccc6cda3 JA |
5763 | |
5764 | `jobs' | |
bb70624e | 5765 | jobs [-lnprs] [JOBSPEC] |
cce855bc | 5766 | jobs -x COMMAND [ARGUMENTS] |
ccc6cda3 JA |
5767 | |
5768 | The first form lists the active jobs. The options have the | |
5769 | following meanings: | |
5770 | ||
5771 | `-l' | |
cce855bc | 5772 | List process IDs in addition to the normal information. |
ccc6cda3 JA |
5773 | |
5774 | `-n' | |
5775 | Display information only about jobs that have changed status | |
cce855bc | 5776 | since the user was last notified of their status. |
ccc6cda3 JA |
5777 | |
5778 | `-p' | |
5779 | List only the process ID of the job's process group leader. | |
5780 | ||
5781 | `-r' | |
5782 | Restrict output to running jobs. | |
5783 | ||
5784 | `-s' | |
5785 | Restrict output to stopped jobs. | |
5786 | ||
5787 | If JOBSPEC is given, output is restricted to information about | |
5788 | that job. If JOBSPEC is not supplied, the status of all jobs is | |
5789 | listed. | |
5790 | ||
5791 | If the `-x' option is supplied, `jobs' replaces any JOBSPEC found | |
5792 | in COMMAND or ARGUMENTS with the corresponding process group ID, | |
5793 | and executes COMMAND, passing it ARGUMENTs, returning its exit | |
5794 | status. | |
5795 | ||
5796 | `kill' | |
cce855bc JA |
5797 | kill [-s SIGSPEC] [-n SIGNUM] [-SIGSPEC] JOBSPEC or PID |
5798 | kill -l [EXIT_STATUS] | |
ccc6cda3 | 5799 | Send a signal specified by SIGSPEC or SIGNUM to the process named |
cce855bc | 5800 | by job specification JOBSPEC or process ID PID. SIGSPEC is either |
9f422431 CR |
5801 | a case-insensitive signal name such as `SIGINT' (with or without |
5802 | the `SIG' prefix) or a signal number; SIGNUM is a signal number. | |
5803 | If SIGSPEC and SIGNUM are not present, `SIGTERM' is used. The | |
5804 | `-l' option lists the signal names. If any arguments are supplied | |
5805 | when `-l' is given, the names of the signals corresponding to the | |
5806 | arguments are listed, and the return status is zero. EXIT_STATUS | |
5807 | is a number specifying a signal number or the exit status of a | |
5808 | process terminated by a signal. The return status is zero if at | |
5809 | least one signal was successfully sent, or non-zero if an error | |
5810 | occurs or an invalid option is encountered. | |
ccc6cda3 JA |
5811 | |
5812 | `wait' | |
eb2bb562 CR |
5813 | wait [JOBSPEC or PID ...] |
5814 | Wait until the child process specified by each process ID PID or | |
5815 | job specification JOBSPEC exits and return the exit status of the | |
5816 | last command waited for. If a job spec is given, all processes in | |
5817 | the job are waited for. If no arguments are given, all currently | |
cce855bc JA |
5818 | active child processes are waited for, and the return status is |
5819 | zero. If neither JOBSPEC nor PID specifies an active child process | |
5820 | of the shell, the return status is 127. | |
ccc6cda3 JA |
5821 | |
5822 | `disown' | |
cce855bc | 5823 | disown [-ar] [-h] [JOBSPEC ...] |
ccc6cda3 JA |
5824 | Without options, each JOBSPEC is removed from the table of active |
5825 | jobs. If the `-h' option is given, the job is not removed from | |
5826 | the table, but is marked so that `SIGHUP' is not sent to the job | |
cce855bc JA |
5827 | if the shell receives a `SIGHUP'. If JOBSPEC is not present, and |
5828 | neither the `-a' nor `-r' option is supplied, the current job is | |
5829 | used. If no JOBSPEC is supplied, the `-a' option means to remove | |
5830 | or mark all jobs; the `-r' option without a JOBSPEC argument | |
5831 | restricts operation to running jobs. | |
ccc6cda3 JA |
5832 | |
5833 | `suspend' | |
5834 | suspend [-f] | |
5835 | Suspend the execution of this shell until it receives a `SIGCONT' | |
5836 | signal. The `-f' option means to suspend even if the shell is a | |
5837 | login shell. | |
5838 | ||
761783bf | 5839 | |
ccc6cda3 JA |
5840 | When job control is not active, the `kill' and `wait' builtins do |
5841 | not accept JOBSPEC arguments. They must be supplied process IDs. | |
5842 | ||
5843 | \1f | |
5844 | File: bashref.info, Node: Job Control Variables, Prev: Job Control Builtins, Up: Job Control | |
5845 | ||
37c41ab1 CR |
5846 | 7.3 Job Control Variables |
5847 | ========================= | |
ccc6cda3 JA |
5848 | |
5849 | `auto_resume' | |
5850 | This variable controls how the shell interacts with the user and | |
5851 | job control. If this variable exists then single word simple | |
cce855bc JA |
5852 | commands without redirections are treated as candidates for |
5853 | resumption of an existing job. There is no ambiguity allowed; if | |
5854 | there is more than one job beginning with the string typed, then | |
5855 | the most recently accessed job will be selected. The name of a | |
5856 | stopped job, in this context, is the command line used to start | |
5857 | it. If this variable is set to the value `exact', the string | |
5858 | supplied must match the name of a stopped job exactly; if set to | |
ccc6cda3 JA |
5859 | `substring', the string supplied needs to match a substring of the |
5860 | name of a stopped job. The `substring' value provides | |
5861 | functionality analogous to the `%?' job ID (*note Job Control | |
28ef6c31 JA |
5862 | Basics::). If set to any other value, the supplied string must be |
5863 | a prefix of a stopped job's name; this provides functionality | |
ccc6cda3 JA |
5864 | analogous to the `%' job ID. |
5865 | ||
761783bf | 5866 | |
ccc6cda3 | 5867 | \1f |
c2a47ea9 | 5868 | File: bashref.info, Node: Command Line Editing, Next: Using History Interactively, Prev: Job Control, Up: Top |
ccc6cda3 | 5869 | |
37c41ab1 CR |
5870 | 8 Command Line Editing |
5871 | ********************** | |
ccc6cda3 | 5872 | |
37c41ab1 | 5873 | This chapter describes the basic features of the GNU command line |
bb70624e JA |
5874 | editing interface. Command line editing is provided by the Readline |
5875 | library, which is used by several different programs, including Bash. | |
ccc6cda3 JA |
5876 | |
5877 | * Menu: | |
5878 | ||
bb70624e JA |
5879 | * Introduction and Notation:: Notation used in this text. |
5880 | * Readline Interaction:: The minimum set of commands for editing a line. | |
5881 | * Readline Init File:: Customizing Readline from a user's view. | |
5882 | * Bindable Readline Commands:: A description of most of the Readline commands | |
5883 | available for binding | |
5884 | * Readline vi Mode:: A short description of how to make Readline | |
5885 | behave like the vi editor. | |
5886 | ||
5887 | * Programmable Completion:: How to specify the possible completions for | |
5888 | a specific command. | |
5889 | * Programmable Completion Builtins:: Builtin commands to specify how to | |
5890 | complete arguments for a particular command. | |
ccc6cda3 JA |
5891 | |
5892 | \1f | |
bb70624e | 5893 | File: bashref.info, Node: Introduction and Notation, Next: Readline Interaction, Up: Command Line Editing |
ccc6cda3 | 5894 | |
37c41ab1 CR |
5895 | 8.1 Introduction to Line Editing |
5896 | ================================ | |
ccc6cda3 | 5897 | |
37c41ab1 | 5898 | The following paragraphs describe the notation used to represent |
bb70624e | 5899 | keystrokes. |
ccc6cda3 | 5900 | |
28ef6c31 | 5901 | The text `C-k' is read as `Control-K' and describes the character |
bb70624e | 5902 | produced when the <k> key is pressed while the Control key is depressed. |
ccc6cda3 | 5903 | |
28ef6c31 | 5904 | The text `M-k' is read as `Meta-K' and describes the character |
bb70624e JA |
5905 | produced when the Meta key (if you have one) is depressed, and the <k> |
5906 | key is pressed. The Meta key is labeled <ALT> on many keyboards. On | |
5907 | keyboards with two keys labeled <ALT> (usually to either side of the | |
5908 | space bar), the <ALT> on the left side is generally set to work as a | |
5909 | Meta key. The <ALT> key on the right may also be configured to work as | |
5910 | a Meta key or may be configured as some other modifier, such as a | |
5911 | Compose key for typing accented characters. | |
5912 | ||
5913 | If you do not have a Meta or <ALT> key, or another key working as a | |
5914 | Meta key, the identical keystroke can be generated by typing <ESC> | |
28ef6c31 JA |
5915 | _first_, and then typing <k>. Either process is known as "metafying" |
5916 | the <k> key. | |
bb70624e | 5917 | |
28ef6c31 JA |
5918 | The text `M-C-k' is read as `Meta-Control-k' and describes the |
5919 | character produced by "metafying" `C-k'. | |
bb70624e JA |
5920 | |
5921 | In addition, several keys have their own names. Specifically, | |
5922 | <DEL>, <ESC>, <LFD>, <SPC>, <RET>, and <TAB> all stand for themselves | |
28ef6c31 JA |
5923 | when seen in this text, or in an init file (*note Readline Init File::). |
5924 | If your keyboard lacks a <LFD> key, typing <C-j> will produce the | |
5925 | desired character. The <RET> key may be labeled <Return> or <Enter> on | |
5926 | some keyboards. | |
ccc6cda3 JA |
5927 | |
5928 | \1f | |
bb70624e | 5929 | File: bashref.info, Node: Readline Interaction, Next: Readline Init File, Prev: Introduction and Notation, Up: Command Line Editing |
cce855bc | 5930 | |
37c41ab1 CR |
5931 | 8.2 Readline Interaction |
5932 | ======================== | |
cce855bc | 5933 | |
37c41ab1 | 5934 | Often during an interactive session you type in a long line of text, |
bb70624e JA |
5935 | only to notice that the first word on the line is misspelled. The |
5936 | Readline library gives you a set of commands for manipulating the text | |
5937 | as you type it in, allowing you to just fix your typo, and not forcing | |
5938 | you to retype the majority of the line. Using these editing commands, | |
5939 | you move the cursor to the place that needs correction, and delete or | |
5940 | insert the text of the corrections. Then, when you are satisfied with | |
28ef6c31 JA |
5941 | the line, you simply press <RET>. You do not have to be at the end of |
5942 | the line to press <RET>; the entire line is accepted regardless of the | |
5943 | location of the cursor within the line. | |
cce855bc | 5944 | |
bb70624e | 5945 | * Menu: |
cce855bc | 5946 | |
bb70624e JA |
5947 | * Readline Bare Essentials:: The least you need to know about Readline. |
5948 | * Readline Movement Commands:: Moving about the input line. | |
5949 | * Readline Killing Commands:: How to delete text, and how to get it back! | |
5950 | * Readline Arguments:: Giving numeric arguments to commands. | |
5951 | * Searching:: Searching through previous lines. | |
cce855bc | 5952 | |
bb70624e JA |
5953 | \1f |
5954 | File: bashref.info, Node: Readline Bare Essentials, Next: Readline Movement Commands, Up: Readline Interaction | |
cce855bc | 5955 | |
37c41ab1 CR |
5956 | 8.2.1 Readline Bare Essentials |
5957 | ------------------------------ | |
cce855bc | 5958 | |
37c41ab1 CR |
5959 | In order to enter characters into the line, simply type them. The typed |
5960 | character appears where the cursor was, and then the cursor moves one | |
5961 | space to the right. If you mistype a character, you can use your erase | |
5962 | character to back up and delete the mistyped character. | |
cce855bc | 5963 | |
bb70624e JA |
5964 | Sometimes you may mistype a character, and not notice the error |
5965 | until you have typed several other characters. In that case, you can | |
28ef6c31 JA |
5966 | type `C-b' to move the cursor to the left, and then correct your |
5967 | mistake. Afterwards, you can move the cursor to the right with `C-f'. | |
cce855bc | 5968 | |
bb70624e JA |
5969 | When you add text in the middle of a line, you will notice that |
5970 | characters to the right of the cursor are `pushed over' to make room | |
5971 | for the text that you have inserted. Likewise, when you delete text | |
5972 | behind the cursor, characters to the right of the cursor are `pulled | |
5973 | back' to fill in the blank space created by the removal of the text. A | |
5974 | list of the bare essentials for editing the text of an input line | |
5975 | follows. | |
cce855bc | 5976 | |
28ef6c31 | 5977 | `C-b' |
bb70624e | 5978 | Move back one character. |
cce855bc | 5979 | |
28ef6c31 | 5980 | `C-f' |
bb70624e | 5981 | Move forward one character. |
cce855bc | 5982 | |
bb70624e JA |
5983 | <DEL> or <Backspace> |
5984 | Delete the character to the left of the cursor. | |
cce855bc | 5985 | |
28ef6c31 | 5986 | `C-d' |
bb70624e | 5987 | Delete the character underneath the cursor. |
cce855bc | 5988 | |
bb70624e JA |
5989 | Printing characters |
5990 | Insert the character into the line at the cursor. | |
cce855bc | 5991 | |
28ef6c31 | 5992 | `C-_' or `C-x C-u' |
bb70624e JA |
5993 | Undo the last editing command. You can undo all the way back to an |
5994 | empty line. | |
cce855bc | 5995 | |
bb70624e JA |
5996 | (Depending on your configuration, the <Backspace> key be set to delete |
5997 | the character to the left of the cursor and the <DEL> key set to delete | |
28ef6c31 | 5998 | the character underneath the cursor, like `C-d', rather than the |
bb70624e | 5999 | character to the left of the cursor.) |
cce855bc JA |
6000 | |
6001 | \1f | |
bb70624e | 6002 | File: bashref.info, Node: Readline Movement Commands, Next: Readline Killing Commands, Prev: Readline Bare Essentials, Up: Readline Interaction |
ccc6cda3 | 6003 | |
37c41ab1 CR |
6004 | 8.2.2 Readline Movement Commands |
6005 | -------------------------------- | |
ccc6cda3 | 6006 | |
37c41ab1 | 6007 | The above table describes the most basic keystrokes that you need in |
bb70624e | 6008 | order to do editing of the input line. For your convenience, many |
28ef6c31 | 6009 | other commands have been added in addition to `C-b', `C-f', `C-d', and |
bb70624e | 6010 | <DEL>. Here are some commands for moving more rapidly about the line. |
ccc6cda3 | 6011 | |
28ef6c31 | 6012 | `C-a' |
bb70624e | 6013 | Move to the start of the line. |
ccc6cda3 | 6014 | |
28ef6c31 | 6015 | `C-e' |
bb70624e | 6016 | Move to the end of the line. |
ccc6cda3 | 6017 | |
28ef6c31 | 6018 | `M-f' |
bb70624e JA |
6019 | Move forward a word, where a word is composed of letters and |
6020 | digits. | |
ccc6cda3 | 6021 | |
28ef6c31 | 6022 | `M-b' |
bb70624e | 6023 | Move backward a word. |
ccc6cda3 | 6024 | |
28ef6c31 | 6025 | `C-l' |
bb70624e | 6026 | Clear the screen, reprinting the current line at the top. |
ccc6cda3 | 6027 | |
28ef6c31 | 6028 | Notice how `C-f' moves forward a character, while `M-f' moves |
bb70624e JA |
6029 | forward a word. It is a loose convention that control keystrokes |
6030 | operate on characters while meta keystrokes operate on words. | |
ccc6cda3 JA |
6031 | |
6032 | \1f | |
bb70624e | 6033 | File: bashref.info, Node: Readline Killing Commands, Next: Readline Arguments, Prev: Readline Movement Commands, Up: Readline Interaction |
ccc6cda3 | 6034 | |
37c41ab1 CR |
6035 | 8.2.3 Readline Killing Commands |
6036 | ------------------------------- | |
ccc6cda3 | 6037 | |
37c41ab1 CR |
6038 | "Killing" text means to delete the text from the line, but to save it |
6039 | away for later use, usually by "yanking" (re-inserting) it back into | |
bb70624e JA |
6040 | the line. (`Cut' and `paste' are more recent jargon for `kill' and |
6041 | `yank'.) | |
ccc6cda3 | 6042 | |
bb70624e JA |
6043 | If the description for a command says that it `kills' text, then you |
6044 | can be sure that you can get the text back in a different (or the same) | |
6045 | place later. | |
ccc6cda3 | 6046 | |
bb70624e JA |
6047 | When you use a kill command, the text is saved in a "kill-ring". |
6048 | Any number of consecutive kills save all of the killed text together, so | |
6049 | that when you yank it back, you get it all. The kill ring is not line | |
6050 | specific; the text that you killed on a previously typed line is | |
37c41ab1 | 6051 | available to be yanked back later, when you are typing another line. |
ccc6cda3 | 6052 | |
bb70624e | 6053 | Here is the list of commands for killing text. |
ccc6cda3 | 6054 | |
28ef6c31 | 6055 | `C-k' |
bb70624e JA |
6056 | Kill the text from the current cursor position to the end of the |
6057 | line. | |
ccc6cda3 | 6058 | |
28ef6c31 | 6059 | `M-d' |
bb70624e JA |
6060 | Kill from the cursor to the end of the current word, or, if between |
6061 | words, to the end of the next word. Word boundaries are the same | |
28ef6c31 | 6062 | as those used by `M-f'. |
ccc6cda3 | 6063 | |
28ef6c31 | 6064 | `M-<DEL>' |
f73dda09 | 6065 | Kill from the cursor the start of the current word, or, if between |
bb70624e | 6066 | words, to the start of the previous word. Word boundaries are the |
28ef6c31 | 6067 | same as those used by `M-b'. |
ccc6cda3 | 6068 | |
28ef6c31 | 6069 | `C-w' |
ccc6cda3 | 6070 | Kill from the cursor to the previous whitespace. This is |
28ef6c31 | 6071 | different than `M-<DEL>' because the word boundaries differ. |
ccc6cda3 | 6072 | |
761783bf | 6073 | |
cce855bc JA |
6074 | Here is how to "yank" the text back into the line. Yanking means to |
6075 | copy the most-recently-killed text from the kill buffer. | |
ccc6cda3 | 6076 | |
28ef6c31 | 6077 | `C-y' |
ccc6cda3 JA |
6078 | Yank the most recently killed text back into the buffer at the |
6079 | cursor. | |
6080 | ||
28ef6c31 | 6081 | `M-y' |
ccc6cda3 | 6082 | Rotate the kill-ring, and yank the new top. You can only do this |
28ef6c31 | 6083 | if the prior command is `C-y' or `M-y'. |
ccc6cda3 JA |
6084 | |
6085 | \1f | |
6086 | File: bashref.info, Node: Readline Arguments, Next: Searching, Prev: Readline Killing Commands, Up: Readline Interaction | |
6087 | ||
37c41ab1 CR |
6088 | 8.2.4 Readline Arguments |
6089 | ------------------------ | |
ccc6cda3 | 6090 | |
37c41ab1 | 6091 | You can pass numeric arguments to Readline commands. Sometimes the |
ccc6cda3 JA |
6092 | argument acts as a repeat count, other times it is the sign of the |
6093 | argument that is significant. If you pass a negative argument to a | |
6094 | command which normally acts in a forward direction, that command will | |
6095 | act in a backward direction. For example, to kill text back to the | |
6096 | start of the line, you might type `M-- C-k'. | |
6097 | ||
6098 | The general way to pass numeric arguments to a command is to type | |
cce855bc | 6099 | meta digits before the command. If the first `digit' typed is a minus |
bb70624e | 6100 | sign (`-'), then the sign of the argument will be negative. Once you |
cce855bc JA |
6101 | have typed one meta digit to get the argument started, you can type the |
6102 | remainder of the digits, and then the command. For example, to give | |
28ef6c31 JA |
6103 | the `C-d' command an argument of 10, you could type `M-1 0 C-d', which |
6104 | will delete the next ten characters on the input line. | |
ccc6cda3 JA |
6105 | |
6106 | \1f | |
6107 | File: bashref.info, Node: Searching, Prev: Readline Arguments, Up: Readline Interaction | |
6108 | ||
37c41ab1 CR |
6109 | 8.2.5 Searching for Commands in the History |
6110 | ------------------------------------------- | |
ccc6cda3 | 6111 | |
37c41ab1 | 6112 | Readline provides commands for searching through the command history |
28ef6c31 JA |
6113 | (*note Bash History Facilities::) for lines containing a specified |
6114 | string. There are two search modes: "incremental" and | |
6115 | "non-incremental". | |
ccc6cda3 JA |
6116 | |
6117 | Incremental searches begin before the user has finished typing the | |
6118 | search string. As each character of the search string is typed, | |
cce855bc | 6119 | Readline displays the next entry from the history matching the string |
ccc6cda3 | 6120 | typed so far. An incremental search requires only as many characters |
bb70624e | 6121 | as needed to find the desired history entry. To search backward in the |
28ef6c31 | 6122 | history for a particular string, type `C-r'. Typing `C-s' searches |
bb70624e JA |
6123 | forward through the history. The characters present in the value of |
6124 | the `isearch-terminators' variable are used to terminate an incremental | |
6125 | search. If that variable has not been assigned a value, the <ESC> and | |
28ef6c31 | 6126 | `C-J' characters will terminate an incremental search. `C-g' will |
bb70624e JA |
6127 | abort an incremental search and restore the original line. When the |
6128 | search is terminated, the history entry containing the search string | |
6129 | becomes the current line. | |
6130 | ||
28ef6c31 JA |
6131 | To find other matching entries in the history list, type `C-r' or |
6132 | `C-s' as appropriate. This will search backward or forward in the | |
bb70624e JA |
6133 | history for the next entry matching the search string typed so far. |
6134 | Any other key sequence bound to a Readline command will terminate the | |
6135 | search and execute that command. For instance, a <RET> will terminate | |
6136 | the search and accept the line, thereby executing the command from the | |
28ef6c31 JA |
6137 | history list. A movement command will terminate the search, make the |
6138 | last line found the current line, and begin editing. | |
ccc6cda3 | 6139 | |
f73dda09 JA |
6140 | Readline remembers the last incremental search string. If two |
6141 | `C-r's are typed without any intervening characters defining a new | |
6142 | search string, any remembered search string is used. | |
6143 | ||
ccc6cda3 JA |
6144 | Non-incremental searches read the entire search string before |
6145 | starting to search for matching history lines. The search string may be | |
cce855bc | 6146 | typed by the user or be part of the contents of the current line. |
ccc6cda3 JA |
6147 | |
6148 | \1f | |
6149 | File: bashref.info, Node: Readline Init File, Next: Bindable Readline Commands, Prev: Readline Interaction, Up: Command Line Editing | |
6150 | ||
37c41ab1 CR |
6151 | 8.3 Readline Init File |
6152 | ====================== | |
ccc6cda3 | 6153 | |
37c41ab1 | 6154 | Although the Readline library comes with a set of Emacs-like |
cce855bc JA |
6155 | keybindings installed by default, it is possible to use a different set |
6156 | of keybindings. Any user can customize programs that use Readline by | |
bb70624e JA |
6157 | putting commands in an "inputrc" file, conventionally in his home |
6158 | directory. The name of this file is taken from the value of the shell | |
6159 | variable `INPUTRC'. If that variable is unset, the default is | |
d3ad40de CR |
6160 | `~/.inputrc'. If that file does not exist or cannot be read, the |
6161 | ultimate default is `/etc/inputrc'. | |
ccc6cda3 JA |
6162 | |
6163 | When a program which uses the Readline library starts up, the init | |
6164 | file is read, and the key bindings are set. | |
6165 | ||
6166 | In addition, the `C-x C-r' command re-reads this init file, thus | |
6167 | incorporating any changes that you might have made to it. | |
6168 | ||
6169 | * Menu: | |
6170 | ||
6171 | * Readline Init File Syntax:: Syntax for the commands in the inputrc file. | |
6172 | ||
6173 | * Conditional Init Constructs:: Conditional key bindings in the inputrc file. | |
6174 | ||
6175 | * Sample Init File:: An example inputrc file. | |
6176 | ||
6177 | \1f | |
6178 | File: bashref.info, Node: Readline Init File Syntax, Next: Conditional Init Constructs, Up: Readline Init File | |
6179 | ||
37c41ab1 CR |
6180 | 8.3.1 Readline Init File Syntax |
6181 | ------------------------------- | |
ccc6cda3 | 6182 | |
37c41ab1 | 6183 | There are only a few basic constructs allowed in the Readline init |
ccc6cda3 JA |
6184 | file. Blank lines are ignored. Lines beginning with a `#' are |
6185 | comments. Lines beginning with a `$' indicate conditional constructs | |
28ef6c31 | 6186 | (*note Conditional Init Constructs::). Other lines denote variable |
ccc6cda3 JA |
6187 | settings and key bindings. |
6188 | ||
6189 | Variable Settings | |
cce855bc JA |
6190 | You can modify the run-time behavior of Readline by altering the |
6191 | values of variables in Readline using the `set' command within the | |
28ef6c31 JA |
6192 | init file. The syntax is simple: |
6193 | ||
6194 | set VARIABLE VALUE | |
6195 | ||
6196 | Here, for example, is how to change from the default Emacs-like | |
6197 | key binding to use `vi' line editing commands: | |
ccc6cda3 JA |
6198 | |
6199 | set editing-mode vi | |
6200 | ||
28ef6c31 | 6201 | Variable names and values, where appropriate, are recognized |
1c72c0cd CR |
6202 | without regard to case. Unrecognized variable names are ignored. |
6203 | ||
6204 | Boolean variables (those that can be set to on or off) are set to | |
6205 | on if the value is null or empty, ON (case-insensitive), or 1. | |
6206 | Any other value results in the variable being set to off. | |
28ef6c31 | 6207 | |
bb70624e JA |
6208 | The `bind -V' command lists the current Readline variable names |
6209 | and values. *Note Bash Builtins::. | |
6210 | ||
cce855bc JA |
6211 | A great deal of run-time behavior is changeable with the following |
6212 | variables. | |
ccc6cda3 JA |
6213 | |
6214 | `bell-style' | |
6215 | Controls what happens when Readline wants to ring the | |
6216 | terminal bell. If set to `none', Readline never rings the | |
6217 | bell. If set to `visible', Readline uses a visible bell if | |
6218 | one is available. If set to `audible' (the default), | |
6219 | Readline attempts to ring the terminal's bell. | |
6220 | ||
eb2bb562 CR |
6221 | `bind-tty-special-chars' |
6222 | If set to `on', Readline attempts to bind the control | |
6223 | characters treated specially by the kernel's terminal driver | |
6224 | to their Readline equivalents. | |
6225 | ||
ccc6cda3 JA |
6226 | `comment-begin' |
6227 | The string to insert at the beginning of the line when the | |
6228 | `insert-comment' command is executed. The default value is | |
6229 | `"#"'. | |
6230 | ||
cce855bc JA |
6231 | `completion-ignore-case' |
6232 | If set to `on', Readline performs filename matching and | |
6233 | completion in a case-insensitive fashion. The default value | |
6234 | is `off'. | |
6235 | ||
ed35cb4a CR |
6236 | `completion-prefix-display-length' |
6237 | The length in characters of the common prefix of a list of | |
6238 | possible completions that is displayed without modification. | |
6239 | When set to a value greater than zero, common prefixes longer | |
6240 | than this value are replaced with an ellipsis when displaying | |
6241 | possible completions. | |
6242 | ||
ccc6cda3 JA |
6243 | `completion-query-items' |
6244 | The number of possible completions that determines when the | |
d3a24ed2 CR |
6245 | user is asked whether the list of possibilities should be |
6246 | displayed. If the number of possible completions is greater | |
6247 | than this value, Readline will ask the user whether or not he | |
6248 | wishes to view them; otherwise, they are simply listed. This | |
6249 | variable must be set to an integer value greater than or | |
1c72c0cd CR |
6250 | equal to 0. A negative value means Readline should never ask. |
6251 | The default limit is `100'. | |
ccc6cda3 JA |
6252 | |
6253 | `convert-meta' | |
6254 | If set to `on', Readline will convert characters with the | |
cce855bc | 6255 | eighth bit set to an ASCII key sequence by stripping the |
bb70624e | 6256 | eighth bit and prefixing an <ESC> character, converting them |
cce855bc | 6257 | to a meta-prefixed key sequence. The default value is `on'. |
ccc6cda3 JA |
6258 | |
6259 | `disable-completion' | |
cce855bc | 6260 | If set to `On', Readline will inhibit word completion. |
ccc6cda3 JA |
6261 | Completion characters will be inserted into the line as if |
6262 | they had been mapped to `self-insert'. The default is `off'. | |
6263 | ||
6264 | `editing-mode' | |
cce855bc JA |
6265 | The `editing-mode' variable controls which default set of key |
6266 | bindings is used. By default, Readline starts up in Emacs | |
6267 | editing mode, where the keystrokes are most similar to Emacs. | |
6268 | This variable can be set to either `emacs' or `vi'. | |
ccc6cda3 JA |
6269 | |
6270 | `enable-keypad' | |
cce855bc | 6271 | When set to `on', Readline will try to enable the application |
ccc6cda3 JA |
6272 | keypad when it is called. Some systems need this to enable |
6273 | the arrow keys. The default is `off'. | |
6274 | ||
6275 | `expand-tilde' | |
6276 | If set to `on', tilde expansion is performed when Readline | |
6277 | attempts word completion. The default is `off'. | |
6278 | ||
1c72c0cd | 6279 | `history-preserve-point' |
d7f49990 CR |
6280 | If set to `on', the history code attempts to place the point |
6281 | (the current cursor position) at the same location on each | |
6282 | history line retrieved with `previous-history' or | |
6283 | `next-history'. The default is `off'. | |
f73dda09 | 6284 | |
6a8fd0ed CR |
6285 | `history-size' |
6286 | Set the maximum number of history entries saved in the | |
6287 | history list. If set to zero, the number of entries in the | |
6288 | history list is not limited. | |
6289 | ||
ccc6cda3 JA |
6290 | `horizontal-scroll-mode' |
6291 | This variable can be set to either `on' or `off'. Setting it | |
cce855bc | 6292 | to `on' means that the text of the lines being edited will |
ccc6cda3 JA |
6293 | scroll horizontally on a single screen line when they are |
6294 | longer than the width of the screen, instead of wrapping onto | |
6295 | a new screen line. By default, this variable is set to `off'. | |
6296 | ||
b72432fd JA |
6297 | `input-meta' |
6298 | If set to `on', Readline will enable eight-bit input (it will | |
28ef6c31 | 6299 | not clear the eighth bit in the characters it reads), |
b72432fd JA |
6300 | regardless of what the terminal claims it can support. The |
6301 | default value is `off'. The name `meta-flag' is a synonym | |
6302 | for this variable. | |
6303 | ||
6304 | `isearch-terminators' | |
6305 | The string of characters that should terminate an incremental | |
6306 | search without subsequently executing the character as a | |
28ef6c31 JA |
6307 | command (*note Searching::). If this variable has not been |
6308 | given a value, the characters <ESC> and `C-J' will terminate | |
b72432fd JA |
6309 | an incremental search. |
6310 | ||
ccc6cda3 JA |
6311 | `keymap' |
6312 | Sets Readline's idea of the current keymap for key binding | |
6313 | commands. Acceptable `keymap' names are `emacs', | |
28ef6c31 | 6314 | `emacs-standard', `emacs-meta', `emacs-ctlx', `vi', `vi-move', |
ccc6cda3 JA |
6315 | `vi-command', and `vi-insert'. `vi' is equivalent to |
6316 | `vi-command'; `emacs' is equivalent to `emacs-standard'. The | |
6317 | default value is `emacs'. The value of the `editing-mode' | |
6318 | variable also affects the default keymap. | |
6319 | ||
6320 | `mark-directories' | |
6321 | If set to `on', completed directory names have a slash | |
6322 | appended. The default is `on'. | |
6323 | ||
6324 | `mark-modified-lines' | |
cce855bc JA |
6325 | This variable, when set to `on', causes Readline to display an |
6326 | asterisk (`*') at the start of history lines which have been | |
6327 | modified. This variable is `off' by default. | |
ccc6cda3 | 6328 | |
7117c2d2 JA |
6329 | `mark-symlinked-directories' |
6330 | If set to `on', completed names which are symbolic links to | |
6331 | directories have a slash appended (subject to the value of | |
6332 | `mark-directories'). The default is `off'. | |
6333 | ||
f73dda09 JA |
6334 | `match-hidden-files' |
6335 | This variable, when set to `on', causes Readline to match | |
6336 | files whose names begin with a `.' (hidden files) when | |
6337 | performing filename completion, unless the leading `.' is | |
6338 | supplied by the user in the filename to be completed. This | |
6339 | variable is `on' by default. | |
6340 | ||
ccc6cda3 JA |
6341 | `output-meta' |
6342 | If set to `on', Readline will display characters with the | |
6343 | eighth bit set directly rather than as a meta-prefixed escape | |
6344 | sequence. The default is `off'. | |
6345 | ||
7117c2d2 JA |
6346 | `page-completions' |
6347 | If set to `on', Readline uses an internal `more'-like pager | |
6348 | to display a screenful of possible completions at a time. | |
6349 | This variable is `on' by default. | |
6350 | ||
cce855bc JA |
6351 | `print-completions-horizontally' |
6352 | If set to `on', Readline will display completions with matches | |
6353 | sorted horizontally in alphabetical order, rather than down | |
6354 | the screen. The default is `off'. | |
6355 | ||
ed35cb4a CR |
6356 | `revert-all-at-newline' |
6357 | If set to `on', Readline will undo all changes to history | |
6358 | lines before returning when `accept-line' is executed. By | |
6359 | default, history lines may be modified and retain individual | |
6360 | undo lists across calls to `readline'. The default is `off'. | |
6361 | ||
ccc6cda3 JA |
6362 | `show-all-if-ambiguous' |
6363 | This alters the default behavior of the completion functions. | |
6364 | If set to `on', words which have more than one possible | |
6365 | completion cause the matches to be listed immediately instead | |
6366 | of ringing the bell. The default value is `off'. | |
6367 | ||
d3a24ed2 CR |
6368 | `show-all-if-unmodified' |
6369 | This alters the default behavior of the completion functions | |
6370 | in a fashion similar to SHOW-ALL-IF-AMBIGUOUS. If set to | |
6371 | `on', words which have more than one possible completion | |
6372 | without any possible partial completion (the possible | |
6373 | completions don't share a common prefix) cause the matches to | |
6374 | be listed immediately instead of ringing the bell. The | |
6375 | default value is `off'. | |
6376 | ||
ccc6cda3 JA |
6377 | `visible-stats' |
6378 | If set to `on', a character denoting a file's type is | |
6379 | appended to the filename when listing possible completions. | |
6380 | The default is `off'. | |
6381 | ||
761783bf | 6382 | |
ccc6cda3 JA |
6383 | Key Bindings |
6384 | The syntax for controlling key bindings in the init file is | |
bb70624e | 6385 | simple. First you need to find the name of the command that you |
cce855bc JA |
6386 | want to change. The following sections contain tables of the |
6387 | command name, the default keybinding, if any, and a short | |
6388 | description of what the command does. | |
ccc6cda3 | 6389 | |
28ef6c31 JA |
6390 | Once you know the name of the command, simply place on a line in |
6391 | the init file the name of the key you wish to bind the command to, | |
d3ad40de CR |
6392 | a colon, and then the name of the command. There can be no space |
6393 | between the key name and the colon - that will be interpreted as | |
6394 | part of the key name. The name of the key can be expressed in | |
6395 | different ways, depending on what you find most comfortable. | |
28ef6c31 JA |
6396 | |
6397 | In addition to command names, readline allows keys to be bound to | |
6398 | a string that is inserted when the key is pressed (a MACRO). | |
ccc6cda3 | 6399 | |
bb70624e JA |
6400 | The `bind -p' command displays Readline function names and |
6401 | bindings in a format that can put directly into an initialization | |
6402 | file. *Note Bash Builtins::. | |
6403 | ||
ccc6cda3 JA |
6404 | KEYNAME: FUNCTION-NAME or MACRO |
6405 | KEYNAME is the name of a key spelled out in English. For | |
6406 | example: | |
6407 | Control-u: universal-argument | |
6408 | Meta-Rubout: backward-kill-word | |
6409 | Control-o: "> output" | |
6410 | ||
28ef6c31 JA |
6411 | In the above example, `C-u' is bound to the function |
6412 | `universal-argument', `M-DEL' is bound to the function | |
6413 | `backward-kill-word', and `C-o' is bound to run the macro | |
ccc6cda3 JA |
6414 | expressed on the right hand side (that is, to insert the text |
6415 | `> output' into the line). | |
6416 | ||
28ef6c31 JA |
6417 | A number of symbolic character names are recognized while |
6418 | processing this key binding syntax: DEL, ESC, ESCAPE, LFD, | |
6419 | NEWLINE, RET, RETURN, RUBOUT, SPACE, SPC, and TAB. | |
6420 | ||
ccc6cda3 JA |
6421 | "KEYSEQ": FUNCTION-NAME or MACRO |
6422 | KEYSEQ differs from KEYNAME above in that strings denoting an | |
6423 | entire key sequence can be specified, by placing the key | |
6424 | sequence in double quotes. Some GNU Emacs style key escapes | |
6425 | can be used, as in the following example, but the special | |
6426 | character names are not recognized. | |
6427 | ||
6428 | "\C-u": universal-argument | |
6429 | "\C-x\C-r": re-read-init-file | |
6430 | "\e[11~": "Function Key 1" | |
6431 | ||
28ef6c31 | 6432 | In the above example, `C-u' is again bound to the function |
ccc6cda3 | 6433 | `universal-argument' (just as it was in the first example), |
28ef6c31 JA |
6434 | `C-x C-r' is bound to the function `re-read-init-file', and |
6435 | `<ESC> <[> <1> <1> <~>' is bound to insert the text `Function | |
6436 | Key 1'. | |
cce855bc | 6437 | |
761783bf | 6438 | |
cce855bc JA |
6439 | The following GNU Emacs style escape sequences are available when |
6440 | specifying key sequences: | |
6441 | ||
6442 | `\C-' | |
6443 | control prefix | |
6444 | ||
6445 | `\M-' | |
6446 | meta prefix | |
6447 | ||
6448 | `\e' | |
6449 | an escape character | |
6450 | ||
6451 | `\\' | |
6452 | backslash | |
6453 | ||
6454 | `\"' | |
bb70624e | 6455 | <">, a double quotation mark |
cce855bc JA |
6456 | |
6457 | `\'' | |
bb70624e | 6458 | <'>, a single quote or apostrophe |
cce855bc JA |
6459 | |
6460 | In addition to the GNU Emacs style escape sequences, a second set | |
6461 | of backslash escapes is available: | |
ccc6cda3 | 6462 | |
cce855bc JA |
6463 | `\a' |
6464 | alert (bell) | |
6465 | ||
6466 | `\b' | |
6467 | backspace | |
6468 | ||
6469 | `\d' | |
6470 | delete | |
6471 | ||
6472 | `\f' | |
6473 | form feed | |
6474 | ||
6475 | `\n' | |
6476 | newline | |
ccc6cda3 | 6477 | |
cce855bc JA |
6478 | `\r' |
6479 | carriage return | |
ccc6cda3 | 6480 | |
cce855bc JA |
6481 | `\t' |
6482 | horizontal tab | |
ccc6cda3 | 6483 | |
cce855bc JA |
6484 | `\v' |
6485 | vertical tab | |
ccc6cda3 | 6486 | |
cce855bc | 6487 | `\NNN' |
f73dda09 | 6488 | the eight-bit character whose value is the octal value NNN |
cce855bc | 6489 | (one to three digits) |
ccc6cda3 | 6490 | |
f73dda09 JA |
6491 | `\xHH' |
6492 | the eight-bit character whose value is the hexadecimal value | |
6493 | HH (one or two hex digits) | |
6494 | ||
cce855bc JA |
6495 | When entering the text of a macro, single or double quotes must be |
6496 | used to indicate a macro definition. Unquoted text is assumed to | |
6497 | be a function name. In the macro body, the backslash escapes | |
6498 | described above are expanded. Backslash will quote any other | |
6499 | character in the macro text, including `"' and `''. For example, | |
6500 | the following binding will make `C-x \' insert a single `\' into | |
6501 | the line: | |
6502 | "\C-x\\": "\\" | |
ccc6cda3 | 6503 | |
761783bf | 6504 | |
ccc6cda3 JA |
6505 | \1f |
6506 | File: bashref.info, Node: Conditional Init Constructs, Next: Sample Init File, Prev: Readline Init File Syntax, Up: Readline Init File | |
6507 | ||
37c41ab1 CR |
6508 | 8.3.2 Conditional Init Constructs |
6509 | --------------------------------- | |
ccc6cda3 | 6510 | |
37c41ab1 | 6511 | Readline implements a facility similar in spirit to the conditional |
ccc6cda3 JA |
6512 | compilation features of the C preprocessor which allows key bindings |
6513 | and variable settings to be performed as the result of tests. There | |
cce855bc | 6514 | are four parser directives used. |
ccc6cda3 JA |
6515 | |
6516 | `$if' | |
6517 | The `$if' construct allows bindings to be made based on the | |
6518 | editing mode, the terminal being used, or the application using | |
6519 | Readline. The text of the test extends to the end of the line; no | |
6520 | characters are required to isolate it. | |
6521 | ||
6522 | `mode' | |
6523 | The `mode=' form of the `$if' directive is used to test | |
6524 | whether Readline is in `emacs' or `vi' mode. This may be | |
6525 | used in conjunction with the `set keymap' command, for | |
6526 | instance, to set bindings in the `emacs-standard' and | |
6527 | `emacs-ctlx' keymaps only if Readline is starting out in | |
6528 | `emacs' mode. | |
6529 | ||
6530 | `term' | |
6531 | The `term=' form may be used to include terminal-specific key | |
6532 | bindings, perhaps to bind the key sequences output by the | |
6533 | terminal's function keys. The word on the right side of the | |
cce855bc JA |
6534 | `=' is tested against both the full name of the terminal and |
6535 | the portion of the terminal name before the first `-'. This | |
ccc6cda3 JA |
6536 | allows `sun' to match both `sun' and `sun-cmd', for instance. |
6537 | ||
6538 | `application' | |
6539 | The APPLICATION construct is used to include | |
6540 | application-specific settings. Each program using the | |
6541 | Readline library sets the APPLICATION NAME, and you can test | |
28ef6c31 JA |
6542 | for a particular value. This could be used to bind key |
6543 | sequences to functions useful for a specific program. For | |
6544 | instance, the following command adds a key sequence that | |
6545 | quotes the current or previous word in Bash: | |
ccc6cda3 JA |
6546 | $if Bash |
6547 | # Quote the current or previous word | |
6548 | "\C-xq": "\eb\"\ef\"" | |
6549 | $endif | |
6550 | ||
6551 | `$endif' | |
cce855bc JA |
6552 | This command, as seen in the previous example, terminates an `$if' |
6553 | command. | |
ccc6cda3 JA |
6554 | |
6555 | `$else' | |
6556 | Commands in this branch of the `$if' directive are executed if the | |
6557 | test fails. | |
6558 | ||
cce855bc JA |
6559 | `$include' |
6560 | This directive takes a single filename as an argument and reads | |
28ef6c31 JA |
6561 | commands and bindings from that file. For example, the following |
6562 | directive reads from `/etc/inputrc': | |
cce855bc JA |
6563 | $include /etc/inputrc |
6564 | ||
ccc6cda3 JA |
6565 | \1f |
6566 | File: bashref.info, Node: Sample Init File, Prev: Conditional Init Constructs, Up: Readline Init File | |
6567 | ||
37c41ab1 CR |
6568 | 8.3.3 Sample Init File |
6569 | ---------------------- | |
ccc6cda3 | 6570 | |
37c41ab1 CR |
6571 | Here is an example of an INPUTRC file. This illustrates key binding, |
6572 | variable assignment, and conditional syntax. | |
ccc6cda3 JA |
6573 | |
6574 | ||
6575 | # This file controls the behaviour of line input editing for | |
7117c2d2 JA |
6576 | # programs that use the GNU Readline library. Existing |
6577 | # programs include FTP, Bash, and GDB. | |
ccc6cda3 JA |
6578 | # |
6579 | # You can re-read the inputrc file with C-x C-r. | |
6580 | # Lines beginning with '#' are comments. | |
cce855bc | 6581 | # |
7117c2d2 JA |
6582 | # First, include any systemwide bindings and variable |
6583 | # assignments from /etc/Inputrc | |
cce855bc | 6584 | $include /etc/Inputrc |
37c41ab1 | 6585 | |
ccc6cda3 JA |
6586 | # |
6587 | # Set various bindings for emacs mode. | |
37c41ab1 | 6588 | |
ccc6cda3 | 6589 | set editing-mode emacs |
37c41ab1 | 6590 | |
ccc6cda3 | 6591 | $if mode=emacs |
37c41ab1 | 6592 | |
ccc6cda3 | 6593 | Meta-Control-h: backward-kill-word Text after the function name is ignored |
37c41ab1 | 6594 | |
ccc6cda3 JA |
6595 | # |
6596 | # Arrow keys in keypad mode | |
6597 | # | |
d166f048 JA |
6598 | #"\M-OD": backward-char |
6599 | #"\M-OC": forward-char | |
6600 | #"\M-OA": previous-history | |
6601 | #"\M-OB": next-history | |
ccc6cda3 JA |
6602 | # |
6603 | # Arrow keys in ANSI mode | |
6604 | # | |
d166f048 JA |
6605 | "\M-[D": backward-char |
6606 | "\M-[C": forward-char | |
6607 | "\M-[A": previous-history | |
6608 | "\M-[B": next-history | |
ccc6cda3 JA |
6609 | # |
6610 | # Arrow keys in 8 bit keypad mode | |
6611 | # | |
d166f048 JA |
6612 | #"\M-\C-OD": backward-char |
6613 | #"\M-\C-OC": forward-char | |
6614 | #"\M-\C-OA": previous-history | |
6615 | #"\M-\C-OB": next-history | |
ccc6cda3 JA |
6616 | # |
6617 | # Arrow keys in 8 bit ANSI mode | |
6618 | # | |
d166f048 JA |
6619 | #"\M-\C-[D": backward-char |
6620 | #"\M-\C-[C": forward-char | |
6621 | #"\M-\C-[A": previous-history | |
6622 | #"\M-\C-[B": next-history | |
37c41ab1 | 6623 | |
ccc6cda3 | 6624 | C-q: quoted-insert |
37c41ab1 | 6625 | |
ccc6cda3 | 6626 | $endif |
37c41ab1 | 6627 | |
ccc6cda3 JA |
6628 | # An old-style binding. This happens to be the default. |
6629 | TAB: complete | |
37c41ab1 | 6630 | |
ccc6cda3 JA |
6631 | # Macros that are convenient for shell interaction |
6632 | $if Bash | |
6633 | # edit the path | |
6634 | "\C-xp": "PATH=${PATH}\e\C-e\C-a\ef\C-f" | |
7117c2d2 JA |
6635 | # prepare to type a quoted word -- |
6636 | # insert open and close double quotes | |
ccc6cda3 JA |
6637 | # and move to just after the open quote |
6638 | "\C-x\"": "\"\"\C-b" | |
7117c2d2 JA |
6639 | # insert a backslash (testing backslash escapes |
6640 | # in sequences and macros) | |
ccc6cda3 JA |
6641 | "\C-x\\": "\\" |
6642 | # Quote the current or previous word | |
6643 | "\C-xq": "\eb\"\ef\"" | |
6644 | # Add a binding to refresh the line, which is unbound | |
6645 | "\C-xr": redraw-current-line | |
6646 | # Edit variable on current line. | |
6647 | "\M-\C-v": "\C-a\C-k$\C-y\M-\C-e\C-a\C-y=" | |
6648 | $endif | |
37c41ab1 | 6649 | |
ccc6cda3 JA |
6650 | # use a visible bell if one is available |
6651 | set bell-style visible | |
37c41ab1 | 6652 | |
ccc6cda3 JA |
6653 | # don't strip characters to 7 bits when reading |
6654 | set input-meta on | |
37c41ab1 | 6655 | |
7117c2d2 JA |
6656 | # allow iso-latin1 characters to be inserted rather |
6657 | # than converted to prefix-meta sequences | |
ccc6cda3 | 6658 | set convert-meta off |
37c41ab1 | 6659 | |
7117c2d2 JA |
6660 | # display characters with the eighth bit set directly |
6661 | # rather than as meta-prefixed characters | |
ccc6cda3 | 6662 | set output-meta on |
37c41ab1 | 6663 | |
7117c2d2 JA |
6664 | # if there are more than 150 possible completions for |
6665 | # a word, ask the user if he wants to see all of them | |
ccc6cda3 | 6666 | set completion-query-items 150 |
37c41ab1 | 6667 | |
ccc6cda3 JA |
6668 | # For FTP |
6669 | $if Ftp | |
6670 | "\C-xg": "get \M-?" | |
6671 | "\C-xt": "put \M-?" | |
6672 | "\M-.": yank-last-arg | |
6673 | $endif | |
6674 | ||
6675 | \1f | |
bb70624e JA |
6676 | File: bashref.info, Node: Bindable Readline Commands, Next: Readline vi Mode, Prev: Readline Init File, Up: Command Line Editing |
6677 | ||
37c41ab1 CR |
6678 | 8.4 Bindable Readline Commands |
6679 | ============================== | |
bb70624e JA |
6680 | |
6681 | * Menu: | |
6682 | ||
6683 | * Commands For Moving:: Moving about the line. | |
6684 | * Commands For History:: Getting at previous lines. | |
6685 | * Commands For Text:: Commands for changing text. | |
6686 | * Commands For Killing:: Commands for killing and yanking. | |
6687 | * Numeric Arguments:: Specifying numeric arguments, repeat counts. | |
6688 | * Commands For Completion:: Getting Readline to do the typing for you. | |
6689 | * Keyboard Macros:: Saving and re-executing typed characters | |
6690 | * Miscellaneous Commands:: Other miscellaneous commands. | |
6691 | ||
6692 | This section describes Readline commands that may be bound to key | |
6693 | sequences. You can list your key bindings by executing `bind -P' or, | |
6694 | for a more terse format, suitable for an INPUTRC file, `bind -p'. | |
28ef6c31 JA |
6695 | (*Note Bash Builtins::.) Command names without an accompanying key |
6696 | sequence are unbound by default. | |
bb70624e | 6697 | |
28ef6c31 JA |
6698 | In the following descriptions, "point" refers to the current cursor |
6699 | position, and "mark" refers to a cursor position saved by the | |
bb70624e | 6700 | `set-mark' command. The text between the point and mark is referred to |
28ef6c31 | 6701 | as the "region". |
bb70624e JA |
6702 | |
6703 | \1f | |
6704 | File: bashref.info, Node: Commands For Moving, Next: Commands For History, Up: Bindable Readline Commands | |
6705 | ||
37c41ab1 CR |
6706 | 8.4.1 Commands For Moving |
6707 | ------------------------- | |
bb70624e JA |
6708 | |
6709 | `beginning-of-line (C-a)' | |
6710 | Move to the start of the current line. | |
6711 | ||
6712 | `end-of-line (C-e)' | |
6713 | Move to the end of the line. | |
6714 | ||
6715 | `forward-char (C-f)' | |
6716 | Move forward a character. | |
6717 | ||
6718 | `backward-char (C-b)' | |
6719 | Move back a character. | |
6720 | ||
6721 | `forward-word (M-f)' | |
6722 | Move forward to the end of the next word. Words are composed of | |
6723 | letters and digits. | |
6724 | ||
6725 | `backward-word (M-b)' | |
6726 | Move back to the start of the current or previous word. Words are | |
6727 | composed of letters and digits. | |
6728 | ||
6729 | `clear-screen (C-l)' | |
6730 | Clear the screen and redraw the current line, leaving the current | |
6731 | line at the top of the screen. | |
6732 | ||
6733 | `redraw-current-line ()' | |
6734 | Refresh the current line. By default, this is unbound. | |
6735 | ||
761783bf | 6736 | |
bb70624e JA |
6737 | \1f |
6738 | File: bashref.info, Node: Commands For History, Next: Commands For Text, Prev: Commands For Moving, Up: Bindable Readline Commands | |
6739 | ||
37c41ab1 CR |
6740 | 8.4.2 Commands For Manipulating The History |
6741 | ------------------------------------------- | |
bb70624e | 6742 | |
28ef6c31 | 6743 | `accept-line (Newline or Return)' |
bb70624e JA |
6744 | Accept the line regardless of where the cursor is. If this line is |
6745 | non-empty, add it to the history list according to the setting of | |
28ef6c31 JA |
6746 | the `HISTCONTROL' and `HISTIGNORE' variables. If this line is a |
6747 | modified history line, then restore the history line to its | |
6748 | original state. | |
bb70624e JA |
6749 | |
6750 | `previous-history (C-p)' | |
28ef6c31 JA |
6751 | Move `back' through the history list, fetching the previous |
6752 | command. | |
bb70624e JA |
6753 | |
6754 | `next-history (C-n)' | |
28ef6c31 | 6755 | Move `forward' through the history list, fetching the next command. |
bb70624e JA |
6756 | |
6757 | `beginning-of-history (M-<)' | |
6758 | Move to the first line in the history. | |
6759 | ||
6760 | `end-of-history (M->)' | |
6761 | Move to the end of the input history, i.e., the line currently | |
6762 | being entered. | |
6763 | ||
6764 | `reverse-search-history (C-r)' | |
6765 | Search backward starting at the current line and moving `up' | |
6766 | through the history as necessary. This is an incremental search. | |
6767 | ||
6768 | `forward-search-history (C-s)' | |
6769 | Search forward starting at the current line and moving `down' | |
6770 | through the the history as necessary. This is an incremental | |
6771 | search. | |
6772 | ||
6773 | `non-incremental-reverse-search-history (M-p)' | |
6774 | Search backward starting at the current line and moving `up' | |
6775 | through the history as necessary using a non-incremental search | |
6776 | for a string supplied by the user. | |
6777 | ||
6778 | `non-incremental-forward-search-history (M-n)' | |
6779 | Search forward starting at the current line and moving `down' | |
6780 | through the the history as necessary using a non-incremental search | |
6781 | for a string supplied by the user. | |
6782 | ||
6783 | `history-search-forward ()' | |
6784 | Search forward through the history for the string of characters | |
6785 | between the start of the current line and the point. This is a | |
6786 | non-incremental search. By default, this command is unbound. | |
6787 | ||
6788 | `history-search-backward ()' | |
6789 | Search backward through the history for the string of characters | |
6790 | between the start of the current line and the point. This is a | |
6791 | non-incremental search. By default, this command is unbound. | |
6792 | ||
6793 | `yank-nth-arg (M-C-y)' | |
6794 | Insert the first argument to the previous command (usually the | |
28ef6c31 JA |
6795 | second word on the previous line) at point. With an argument N, |
6796 | insert the Nth word from the previous command (the words in the | |
6797 | previous command begin with word 0). A negative argument inserts | |
eb2bb562 CR |
6798 | the Nth word from the end of the previous command. Once the |
6799 | argument N is computed, the argument is extracted as if the `!N' | |
6800 | history expansion had been specified. | |
bb70624e | 6801 | |
28ef6c31 | 6802 | `yank-last-arg (M-. or M-_)' |
bb70624e JA |
6803 | Insert last argument to the previous command (the last word of the |
6804 | previous history entry). With an argument, behave exactly like | |
6805 | `yank-nth-arg'. Successive calls to `yank-last-arg' move back | |
6806 | through the history list, inserting the last argument of each line | |
eb2bb562 CR |
6807 | in turn. The history expansion facilities are used to extract the |
6808 | last argument, as if the `!$' history expansion had been specified. | |
bb70624e | 6809 | |
761783bf | 6810 | |
bb70624e JA |
6811 | \1f |
6812 | File: bashref.info, Node: Commands For Text, Next: Commands For Killing, Prev: Commands For History, Up: Bindable Readline Commands | |
6813 | ||
37c41ab1 CR |
6814 | 8.4.3 Commands For Changing Text |
6815 | -------------------------------- | |
bb70624e JA |
6816 | |
6817 | `delete-char (C-d)' | |
28ef6c31 JA |
6818 | Delete the character at point. If point is at the beginning of |
6819 | the line, there are no characters in the line, and the last | |
6820 | character typed was not bound to `delete-char', then return EOF. | |
bb70624e JA |
6821 | |
6822 | `backward-delete-char (Rubout)' | |
6823 | Delete the character behind the cursor. A numeric argument means | |
6824 | to kill the characters instead of deleting them. | |
6825 | ||
6826 | `forward-backward-delete-char ()' | |
6827 | Delete the character under the cursor, unless the cursor is at the | |
6828 | end of the line, in which case the character behind the cursor is | |
6829 | deleted. By default, this is not bound to a key. | |
6830 | ||
28ef6c31 | 6831 | `quoted-insert (C-q or C-v)' |
bb70624e | 6832 | Add the next character typed to the line verbatim. This is how to |
28ef6c31 | 6833 | insert key sequences like `C-q', for example. |
bb70624e JA |
6834 | |
6835 | `self-insert (a, b, A, 1, !, ...)' | |
6836 | Insert yourself. | |
6837 | ||
6838 | `transpose-chars (C-t)' | |
6839 | Drag the character before the cursor forward over the character at | |
6840 | the cursor, moving the cursor forward as well. If the insertion | |
6841 | point is at the end of the line, then this transposes the last two | |
6842 | characters of the line. Negative arguments have no effect. | |
6843 | ||
6844 | `transpose-words (M-t)' | |
6845 | Drag the word before point past the word after point, moving point | |
f73dda09 JA |
6846 | past that word as well. If the insertion point is at the end of |
6847 | the line, this transposes the last two words on the line. | |
bb70624e JA |
6848 | |
6849 | `upcase-word (M-u)' | |
6850 | Uppercase the current (or following) word. With a negative | |
6851 | argument, uppercase the previous word, but do not move the cursor. | |
6852 | ||
6853 | `downcase-word (M-l)' | |
6854 | Lowercase the current (or following) word. With a negative | |
6855 | argument, lowercase the previous word, but do not move the cursor. | |
6856 | ||
6857 | `capitalize-word (M-c)' | |
6858 | Capitalize the current (or following) word. With a negative | |
6859 | argument, capitalize the previous word, but do not move the cursor. | |
6860 | ||
7117c2d2 JA |
6861 | `overwrite-mode ()' |
6862 | Toggle overwrite mode. With an explicit positive numeric argument, | |
6863 | switches to overwrite mode. With an explicit non-positive numeric | |
6864 | argument, switches to insert mode. This command affects only | |
6865 | `emacs' mode; `vi' mode does overwrite differently. Each call to | |
6866 | `readline()' starts in insert mode. | |
6867 | ||
6868 | In overwrite mode, characters bound to `self-insert' replace the | |
6869 | text at point rather than pushing the text to the right. | |
6870 | Characters bound to `backward-delete-char' replace the character | |
6871 | before point with a space. | |
6872 | ||
6873 | By default, this command is unbound. | |
6874 | ||
761783bf | 6875 | |
bb70624e JA |
6876 | \1f |
6877 | File: bashref.info, Node: Commands For Killing, Next: Numeric Arguments, Prev: Commands For Text, Up: Bindable Readline Commands | |
6878 | ||
37c41ab1 CR |
6879 | 8.4.4 Killing And Yanking |
6880 | ------------------------- | |
bb70624e JA |
6881 | |
6882 | `kill-line (C-k)' | |
6883 | Kill the text from point to the end of the line. | |
6884 | ||
6885 | `backward-kill-line (C-x Rubout)' | |
6886 | Kill backward to the beginning of the line. | |
6887 | ||
6888 | `unix-line-discard (C-u)' | |
6889 | Kill backward from the cursor to the beginning of the current line. | |
6890 | ||
6891 | `kill-whole-line ()' | |
28ef6c31 JA |
6892 | Kill all characters on the current line, no matter where point is. |
6893 | By default, this is unbound. | |
bb70624e JA |
6894 | |
6895 | `kill-word (M-d)' | |
6896 | Kill from point to the end of the current word, or if between | |
6897 | words, to the end of the next word. Word boundaries are the same | |
6898 | as `forward-word'. | |
6899 | ||
28ef6c31 | 6900 | `backward-kill-word (M-<DEL>)' |
bb70624e JA |
6901 | Kill the word behind point. Word boundaries are the same as |
6902 | `backward-word'. | |
6903 | ||
6904 | `unix-word-rubout (C-w)' | |
6905 | Kill the word behind point, using white space as a word boundary. | |
6906 | The killed text is saved on the kill-ring. | |
6907 | ||
113d85a4 CR |
6908 | `unix-filename-rubout ()' |
6909 | Kill the word behind point, using white space and the slash | |
6910 | character as the word boundaries. The killed text is saved on the | |
6911 | kill-ring. | |
6912 | ||
bb70624e JA |
6913 | `delete-horizontal-space ()' |
6914 | Delete all spaces and tabs around point. By default, this is | |
6915 | unbound. | |
6916 | ||
6917 | `kill-region ()' | |
6918 | Kill the text in the current region. By default, this command is | |
6919 | unbound. | |
6920 | ||
6921 | `copy-region-as-kill ()' | |
6922 | Copy the text in the region to the kill buffer, so it can be yanked | |
6923 | right away. By default, this command is unbound. | |
6924 | ||
6925 | `copy-backward-word ()' | |
6926 | Copy the word before point to the kill buffer. The word | |
6927 | boundaries are the same as `backward-word'. By default, this | |
6928 | command is unbound. | |
6929 | ||
6930 | `copy-forward-word ()' | |
6931 | Copy the word following point to the kill buffer. The word | |
6932 | boundaries are the same as `forward-word'. By default, this | |
6933 | command is unbound. | |
6934 | ||
6935 | `yank (C-y)' | |
28ef6c31 | 6936 | Yank the top of the kill ring into the buffer at point. |
bb70624e JA |
6937 | |
6938 | `yank-pop (M-y)' | |
6939 | Rotate the kill-ring, and yank the new top. You can only do this | |
28ef6c31 | 6940 | if the prior command is `yank' or `yank-pop'. |
bb70624e JA |
6941 | |
6942 | \1f | |
6943 | File: bashref.info, Node: Numeric Arguments, Next: Commands For Completion, Prev: Commands For Killing, Up: Bindable Readline Commands | |
6944 | ||
37c41ab1 CR |
6945 | 8.4.5 Specifying Numeric Arguments |
6946 | ---------------------------------- | |
bb70624e JA |
6947 | |
6948 | `digit-argument (M-0, M-1, ... M--)' | |
6949 | Add this digit to the argument already accumulating, or start a new | |
28ef6c31 | 6950 | argument. `M--' starts a negative argument. |
bb70624e JA |
6951 | |
6952 | `universal-argument ()' | |
6953 | This is another way to specify an argument. If this command is | |
6954 | followed by one or more digits, optionally with a leading minus | |
6955 | sign, those digits define the argument. If the command is | |
6956 | followed by digits, executing `universal-argument' again ends the | |
6957 | numeric argument, but is otherwise ignored. As a special case, if | |
6958 | this command is immediately followed by a character that is | |
6959 | neither a digit or minus sign, the argument count for the next | |
6960 | command is multiplied by four. The argument count is initially | |
6961 | one, so executing this function the first time makes the argument | |
6962 | count four, a second time makes the argument count sixteen, and so | |
6963 | on. By default, this is not bound to a key. | |
6964 | ||
6965 | \1f | |
6966 | File: bashref.info, Node: Commands For Completion, Next: Keyboard Macros, Prev: Numeric Arguments, Up: Bindable Readline Commands | |
6967 | ||
37c41ab1 CR |
6968 | 8.4.6 Letting Readline Type For You |
6969 | ----------------------------------- | |
bb70624e | 6970 | |
28ef6c31 JA |
6971 | `complete (<TAB>)' |
6972 | Attempt to perform completion on the text before point. The | |
6973 | actual completion performed is application-specific. Bash | |
6974 | attempts completion treating the text as a variable (if the text | |
6975 | begins with `$'), username (if the text begins with `~'), hostname | |
6976 | (if the text begins with `@'), or command (including aliases and | |
6977 | functions) in turn. If none of these produces a match, filename | |
6978 | completion is attempted. | |
bb70624e JA |
6979 | |
6980 | `possible-completions (M-?)' | |
28ef6c31 | 6981 | List the possible completions of the text before point. |
bb70624e JA |
6982 | |
6983 | `insert-completions (M-*)' | |
6984 | Insert all completions of the text before point that would have | |
6985 | been generated by `possible-completions'. | |
6986 | ||
6987 | `menu-complete ()' | |
6988 | Similar to `complete', but replaces the word to be completed with | |
6989 | a single match from the list of possible completions. Repeated | |
6990 | execution of `menu-complete' steps through the list of possible | |
6991 | completions, inserting each match in turn. At the end of the list | |
28ef6c31 JA |
6992 | of completions, the bell is rung (subject to the setting of |
6993 | `bell-style') and the original text is restored. An argument of N | |
6994 | moves N positions forward in the list of matches; a negative | |
6995 | argument may be used to move backward through the list. This | |
6996 | command is intended to be bound to <TAB>, but is unbound by | |
bb70624e JA |
6997 | default. |
6998 | ||
6999 | `delete-char-or-list ()' | |
7000 | Deletes the character under the cursor if not at the beginning or | |
7001 | end of the line (like `delete-char'). If at the end of the line, | |
7002 | behaves identically to `possible-completions'. This command is | |
7003 | unbound by default. | |
7004 | ||
7005 | `complete-filename (M-/)' | |
7006 | Attempt filename completion on the text before point. | |
7007 | ||
7008 | `possible-filename-completions (C-x /)' | |
7009 | List the possible completions of the text before point, treating | |
7010 | it as a filename. | |
7011 | ||
7012 | `complete-username (M-~)' | |
7013 | Attempt completion on the text before point, treating it as a | |
7014 | username. | |
7015 | ||
7016 | `possible-username-completions (C-x ~)' | |
7017 | List the possible completions of the text before point, treating | |
7018 | it as a username. | |
7019 | ||
7020 | `complete-variable (M-$)' | |
7021 | Attempt completion on the text before point, treating it as a | |
7022 | shell variable. | |
7023 | ||
7024 | `possible-variable-completions (C-x $)' | |
7025 | List the possible completions of the text before point, treating | |
7026 | it as a shell variable. | |
7027 | ||
7028 | `complete-hostname (M-@)' | |
7029 | Attempt completion on the text before point, treating it as a | |
7030 | hostname. | |
7031 | ||
7032 | `possible-hostname-completions (C-x @)' | |
7033 | List the possible completions of the text before point, treating | |
7034 | it as a hostname. | |
7035 | ||
7036 | `complete-command (M-!)' | |
7037 | Attempt completion on the text before point, treating it as a | |
7038 | command name. Command completion attempts to match the text | |
7039 | against aliases, reserved words, shell functions, shell builtins, | |
7040 | and finally executable filenames, in that order. | |
7041 | ||
7042 | `possible-command-completions (C-x !)' | |
7043 | List the possible completions of the text before point, treating | |
7044 | it as a command name. | |
7045 | ||
28ef6c31 | 7046 | `dynamic-complete-history (M-<TAB>)' |
bb70624e JA |
7047 | Attempt completion on the text before point, comparing the text |
7048 | against lines from the history list for possible completion | |
7049 | matches. | |
7050 | ||
ed35cb4a CR |
7051 | `dabbrev-expand ()' |
7052 | Attempt menu completion on the text before point, comparing the | |
7053 | text against lines from the history list for possible completion | |
7054 | matches. | |
7055 | ||
bb70624e JA |
7056 | `complete-into-braces (M-{)' |
7057 | Perform filename completion and insert the list of possible | |
7058 | completions enclosed within braces so the list is available to the | |
28ef6c31 | 7059 | shell (*note Brace Expansion::). |
bb70624e | 7060 | |
761783bf | 7061 | |
bb70624e JA |
7062 | \1f |
7063 | File: bashref.info, Node: Keyboard Macros, Next: Miscellaneous Commands, Prev: Commands For Completion, Up: Bindable Readline Commands | |
7064 | ||
37c41ab1 CR |
7065 | 8.4.7 Keyboard Macros |
7066 | --------------------- | |
bb70624e JA |
7067 | |
7068 | `start-kbd-macro (C-x ()' | |
7069 | Begin saving the characters typed into the current keyboard macro. | |
7070 | ||
7071 | `end-kbd-macro (C-x ))' | |
7072 | Stop saving the characters typed into the current keyboard macro | |
7073 | and save the definition. | |
7074 | ||
7075 | `call-last-kbd-macro (C-x e)' | |
7076 | Re-execute the last keyboard macro defined, by making the | |
7077 | characters in the macro appear as if typed at the keyboard. | |
7078 | ||
761783bf | 7079 | |
bb70624e JA |
7080 | \1f |
7081 | File: bashref.info, Node: Miscellaneous Commands, Prev: Keyboard Macros, Up: Bindable Readline Commands | |
7082 | ||
37c41ab1 CR |
7083 | 8.4.8 Some Miscellaneous Commands |
7084 | --------------------------------- | |
bb70624e JA |
7085 | |
7086 | `re-read-init-file (C-x C-r)' | |
7087 | Read in the contents of the INPUTRC file, and incorporate any | |
7088 | bindings or variable assignments found there. | |
7089 | ||
7090 | `abort (C-g)' | |
7091 | Abort the current editing command and ring the terminal's bell | |
7092 | (subject to the setting of `bell-style'). | |
7093 | ||
7094 | `do-uppercase-version (M-a, M-b, M-X, ...)' | |
7095 | If the metafied character X is lowercase, run the command that is | |
7096 | bound to the corresponding uppercase character. | |
7097 | ||
28ef6c31 JA |
7098 | `prefix-meta (<ESC>)' |
7099 | Metafy the next character typed. This is for keyboards without a | |
7100 | meta key. Typing `<ESC> f' is equivalent to typing `M-f'. | |
bb70624e | 7101 | |
28ef6c31 | 7102 | `undo (C-_ or C-x C-u)' |
bb70624e JA |
7103 | Incremental undo, separately remembered for each line. |
7104 | ||
7105 | `revert-line (M-r)' | |
7106 | Undo all changes made to this line. This is like executing the | |
7107 | `undo' command enough times to get back to the beginning. | |
7108 | ||
7109 | `tilde-expand (M-&)' | |
7110 | Perform tilde expansion on the current word. | |
7111 | ||
7112 | `set-mark (C-@)' | |
28ef6c31 JA |
7113 | Set the mark to the point. If a numeric argument is supplied, the |
7114 | mark is set to that position. | |
bb70624e JA |
7115 | |
7116 | `exchange-point-and-mark (C-x C-x)' | |
7117 | Swap the point with the mark. The current cursor position is set | |
7118 | to the saved position, and the old cursor position is saved as the | |
7119 | mark. | |
7120 | ||
7121 | `character-search (C-])' | |
7122 | A character is read and point is moved to the next occurrence of | |
7123 | that character. A negative count searches for previous | |
7124 | occurrences. | |
7125 | ||
7126 | `character-search-backward (M-C-])' | |
7127 | A character is read and point is moved to the previous occurrence | |
7128 | of that character. A negative count searches for subsequent | |
7129 | occurrences. | |
7130 | ||
7131 | `insert-comment (M-#)' | |
7117c2d2 JA |
7132 | Without a numeric argument, the value of the `comment-begin' |
7133 | variable is inserted at the beginning of the current line. If a | |
7134 | numeric argument is supplied, this command acts as a toggle: if | |
7135 | the characters at the beginning of the line do not match the value | |
7136 | of `comment-begin', the value is inserted, otherwise the | |
7137 | characters in `comment-begin' are deleted from the beginning of | |
7138 | the line. In either case, the line is accepted as if a newline | |
7139 | had been typed. The default value of `comment-begin' causes this | |
7140 | command to make the current line a shell comment. If a numeric | |
7141 | argument causes the comment character to be removed, the line will | |
7142 | be executed by the shell. | |
bb70624e JA |
7143 | |
7144 | `dump-functions ()' | |
7145 | Print all of the functions and their key bindings to the Readline | |
7146 | output stream. If a numeric argument is supplied, the output is | |
7147 | formatted in such a way that it can be made part of an INPUTRC | |
7148 | file. This command is unbound by default. | |
7149 | ||
7150 | `dump-variables ()' | |
7151 | Print all of the settable variables and their values to the | |
7152 | Readline output stream. If a numeric argument is supplied, the | |
7153 | output is formatted in such a way that it can be made part of an | |
7154 | INPUTRC file. This command is unbound by default. | |
7155 | ||
7156 | `dump-macros ()' | |
7157 | Print all of the Readline key sequences bound to macros and the | |
28ef6c31 JA |
7158 | strings they output. If a numeric argument is supplied, the |
7159 | output is formatted in such a way that it can be made part of an | |
7160 | INPUTRC file. This command is unbound by default. | |
bb70624e | 7161 | |
7117c2d2 JA |
7162 | `glob-complete-word (M-g)' |
7163 | The word before point is treated as a pattern for pathname | |
7164 | expansion, with an asterisk implicitly appended. This pattern is | |
7165 | used to generate a list of matching file names for possible | |
7166 | completions. | |
7167 | ||
bb70624e JA |
7168 | `glob-expand-word (C-x *)' |
7169 | The word before point is treated as a pattern for pathname | |
7170 | expansion, and the list of matching file names is inserted, | |
7117c2d2 JA |
7171 | replacing the word. If a numeric argument is supplied, a `*' is |
7172 | appended before pathname expansion. | |
bb70624e JA |
7173 | |
7174 | `glob-list-expansions (C-x g)' | |
7175 | The list of expansions that would have been generated by | |
7117c2d2 JA |
7176 | `glob-expand-word' is displayed, and the line is redrawn. If a |
7177 | numeric argument is supplied, a `*' is appended before pathname | |
7178 | expansion. | |
bb70624e JA |
7179 | |
7180 | `display-shell-version (C-x C-v)' | |
7181 | Display version information about the current instance of Bash. | |
7182 | ||
7183 | `shell-expand-line (M-C-e)' | |
7184 | Expand the line as the shell does. This performs alias and | |
7185 | history expansion as well as all of the shell word expansions | |
28ef6c31 | 7186 | (*note Shell Expansions::). |
bb70624e JA |
7187 | |
7188 | `history-expand-line (M-^)' | |
7189 | Perform history expansion on the current line. | |
7190 | ||
7191 | `magic-space ()' | |
7192 | Perform history expansion on the current line and insert a space | |
28ef6c31 | 7193 | (*note History Interaction::). |
bb70624e JA |
7194 | |
7195 | `alias-expand-line ()' | |
28ef6c31 | 7196 | Perform alias expansion on the current line (*note Aliases::). |
bb70624e JA |
7197 | |
7198 | `history-and-alias-expand-line ()' | |
7199 | Perform history and alias expansion on the current line. | |
7200 | ||
28ef6c31 | 7201 | `insert-last-argument (M-. or M-_)' |
bb70624e JA |
7202 | A synonym for `yank-last-arg'. |
7203 | ||
7204 | `operate-and-get-next (C-o)' | |
7205 | Accept the current line for execution and fetch the next line | |
7206 | relative to the current line from the history for editing. Any | |
7207 | argument is ignored. | |
7208 | ||
7117c2d2 JA |
7209 | `edit-and-execute-command (C-xC-e)' |
7210 | Invoke an editor on the current command line, and execute the | |
c2258e1c | 7211 | result as shell commands. Bash attempts to invoke `$VISUAL', |
7117c2d2 | 7212 | `$EDITOR', and `emacs' as the editor, in that order. |
bb70624e | 7213 | |
761783bf | 7214 | |
bb70624e JA |
7215 | \1f |
7216 | File: bashref.info, Node: Readline vi Mode, Next: Programmable Completion, Prev: Bindable Readline Commands, Up: Command Line Editing | |
7217 | ||
37c41ab1 CR |
7218 | 8.5 Readline vi Mode |
7219 | ==================== | |
bb70624e | 7220 | |
37c41ab1 | 7221 | While the Readline library does not have a full set of `vi' editing |
bb70624e JA |
7222 | functions, it does contain enough to allow simple editing of the line. |
7223 | The Readline `vi' mode behaves as specified in the POSIX 1003.2 | |
7224 | standard. | |
7225 | ||
7226 | In order to switch interactively between `emacs' and `vi' editing | |
7227 | modes, use the `set -o emacs' and `set -o vi' commands (*note The Set | |
28ef6c31 | 7228 | Builtin::). The Readline default is `emacs' mode. |
bb70624e JA |
7229 | |
7230 | When you enter a line in `vi' mode, you are already placed in | |
7231 | `insertion' mode, as if you had typed an `i'. Pressing <ESC> switches | |
7232 | you into `command' mode, where you can edit the text of the line with | |
7233 | the standard `vi' movement keys, move to previous history lines with | |
7234 | `k' and subsequent lines with `j', and so forth. | |
7235 | ||
7236 | \1f | |
7237 | File: bashref.info, Node: Programmable Completion, Next: Programmable Completion Builtins, Prev: Readline vi Mode, Up: Command Line Editing | |
7238 | ||
37c41ab1 CR |
7239 | 8.6 Programmable Completion |
7240 | =========================== | |
bb70624e | 7241 | |
37c41ab1 | 7242 | When word completion is attempted for an argument to a command for |
bb70624e | 7243 | which a completion specification (a COMPSPEC) has been defined using |
28ef6c31 | 7244 | the `complete' builtin (*note Programmable Completion Builtins::), the |
bb70624e JA |
7245 | programmable completion facilities are invoked. |
7246 | ||
7247 | First, the command name is identified. If a compspec has been | |
7248 | defined for that command, the compspec is used to generate the list of | |
7249 | possible completions for the word. If the command word is a full | |
7250 | pathname, a compspec for the full pathname is searched for first. If | |
7251 | no compspec is found for the full pathname, an attempt is made to find | |
7252 | a compspec for the portion following the final slash. | |
7253 | ||
7254 | Once a compspec has been found, it is used to generate the list of | |
7255 | matching words. If a compspec is not found, the default Bash completion | |
28ef6c31 | 7256 | described above (*note Commands For Completion::) is performed. |
bb70624e JA |
7257 | |
7258 | First, the actions specified by the compspec are used. Only matches | |
7259 | which are prefixed by the word being completed are returned. When the | |
7260 | `-f' or `-d' option is used for filename or directory name completion, | |
7261 | the shell variable `FIGNORE' is used to filter the matches. *Note Bash | |
7262 | Variables::, for a description of `FIGNORE'. | |
7263 | ||
7264 | Any completions specified by a filename expansion pattern to the | |
7265 | `-G' option are generated next. The words generated by the pattern | |
7266 | need not match the word being completed. The `GLOBIGNORE' shell | |
7267 | variable is not used to filter the matches, but the `FIGNORE' shell | |
7268 | variable is used. | |
7269 | ||
7270 | Next, the string specified as the argument to the `-W' option is | |
7271 | considered. The string is first split using the characters in the `IFS' | |
7272 | special variable as delimiters. Shell quoting is honored. Each word | |
7273 | is then expanded using brace expansion, tilde expansion, parameter and | |
2206f89a CR |
7274 | variable expansion, command substitution, and arithmetic expansion, as |
7275 | described above (*note Shell Expansions::). The results are split | |
7276 | using the rules described above (*note Word Splitting::). The results | |
7277 | of the expansion are prefix-matched against the word being completed, | |
7278 | and the matching words become the possible completions. | |
bb70624e JA |
7279 | |
7280 | After these matches have been generated, any shell function or | |
7281 | command specified with the `-F' and `-C' options is invoked. When the | |
d3ad40de CR |
7282 | command or function is invoked, the `COMP_LINE', `COMP_POINT', |
7283 | `COMP_KEY', and `COMP_TYPE' variables are assigned values as described | |
7284 | above (*note Bash Variables::). If a shell function is being invoked, | |
7285 | the `COMP_WORDS' and `COMP_CWORD' variables are also set. When the | |
7286 | function or command is invoked, the first argument is the name of the | |
7287 | command whose arguments are being completed, the second argument is the | |
7288 | word being completed, and the third argument is the word preceding the | |
7289 | word being completed on the current command line. No filtering of the | |
7290 | generated completions against the word being completed is performed; | |
7291 | the function or command has complete freedom in generating the matches. | |
bb70624e JA |
7292 | |
7293 | Any function specified with `-F' is invoked first. The function may | |
6a8fd0ed CR |
7294 | use any of the shell facilities, including the `compgen' and `compopt' |
7295 | builtins described below (*note Programmable Completion Builtins::), to | |
7296 | generate the matches. It must put the possible completions in the | |
7297 | `COMPREPLY' array variable. | |
bb70624e JA |
7298 | |
7299 | Next, any command specified with the `-C' option is invoked in an | |
7300 | environment equivalent to command substitution. It should print a list | |
7301 | of completions, one per line, to the standard output. Backslash may be | |
7302 | used to escape a newline, if necessary. | |
7303 | ||
7304 | After all of the possible completions are generated, any filter | |
7305 | specified with the `-X' option is applied to the list. The filter is a | |
7306 | pattern as used for pathname expansion; a `&' in the pattern is | |
7307 | replaced with the text of the word being completed. A literal `&' may | |
7308 | be escaped with a backslash; the backslash is removed before attempting | |
7309 | a match. Any completion that matches the pattern will be removed from | |
7310 | the list. A leading `!' negates the pattern; in this case any | |
7311 | completion not matching the pattern will be removed. | |
7312 | ||
7313 | Finally, any prefix and suffix specified with the `-P' and `-S' | |
7314 | options are added to each member of the completion list, and the result | |
7315 | is returned to the Readline completion code as the list of possible | |
7316 | completions. | |
7317 | ||
28ef6c31 JA |
7318 | If the previously-applied actions do not generate any matches, and |
7319 | the `-o dirnames' option was supplied to `complete' when the compspec | |
7320 | was defined, directory name completion is attempted. | |
7321 | ||
d3a24ed2 CR |
7322 | If the `-o plusdirs' option was supplied to `complete' when the |
7323 | compspec was defined, directory name completion is attempted and any | |
7324 | matches are added to the results of the other actions. | |
7325 | ||
28ef6c31 JA |
7326 | By default, if a compspec is found, whatever it generates is |
7327 | returned to the completion code as the full set of possible completions. | |
7328 | The default Bash completions are not attempted, and the Readline default | |
d3a24ed2 CR |
7329 | of filename completion is disabled. If the `-o bashdefault' option was |
7330 | supplied to `complete' when the compspec was defined, the default Bash | |
7331 | completions are attempted if the compspec generates no matches. If the | |
7332 | `-o default' option was supplied to `complete' when the compspec was | |
7333 | defined, Readline's default completion will be performed if the | |
7334 | compspec (and, if attempted, the default Bash completions) generate no | |
28ef6c31 | 7335 | matches. |
bb70624e | 7336 | |
7117c2d2 JA |
7337 | When a compspec indicates that directory name completion is desired, |
7338 | the programmable completion functions force Readline to append a slash | |
7339 | to completed names which are symbolic links to directories, subject to | |
7340 | the value of the MARK-DIRECTORIES Readline variable, regardless of the | |
7341 | setting of the MARK-SYMLINKED-DIRECTORIES Readline variable. | |
7342 | ||
bb70624e JA |
7343 | \1f |
7344 | File: bashref.info, Node: Programmable Completion Builtins, Prev: Programmable Completion, Up: Command Line Editing | |
7345 | ||
37c41ab1 CR |
7346 | 8.7 Programmable Completion Builtins |
7347 | ==================================== | |
bb70624e | 7348 | |
37c41ab1 | 7349 | Two builtin commands are available to manipulate the programmable |
bb70624e JA |
7350 | completion facilities. |
7351 | ||
7352 | `compgen' | |
7353 | `compgen [OPTION] [WORD]' | |
7354 | ||
7355 | Generate possible completion matches for WORD according to the | |
7356 | OPTIONs, which may be any option accepted by the `complete' | |
7357 | builtin with the exception of `-p' and `-r', and write the matches | |
7358 | to the standard output. When using the `-F' or `-C' options, the | |
7359 | various shell variables set by the programmable completion | |
7360 | facilities, while available, will not have useful values. | |
7361 | ||
7362 | The matches will be generated in the same way as if the | |
7363 | programmable completion code had generated them directly from a | |
7364 | completion specification with the same flags. If WORD is | |
7365 | specified, only those completions matching WORD will be displayed. | |
7366 | ||
7367 | The return value is true unless an invalid option is supplied, or | |
7368 | no matches were generated. | |
7369 | ||
7370 | `complete' | |
ed35cb4a | 7371 | `complete [-abcdefgjksuv] [-o COMP-OPTION] [-E] [-A ACTION] [-G GLOBPAT] [-W WORDLIST] |
d3ad40de CR |
7372 | [-F FUNCTION] [-C COMMAND] [-X FILTERPAT] |
7373 | [-P PREFIX] [-S SUFFIX] NAME [NAME ...]' | |
ed35cb4a | 7374 | `complete -pr [-E] [NAME ...]' |
bb70624e JA |
7375 | |
7376 | Specify how arguments to each NAME should be completed. If the | |
7377 | `-p' option is supplied, or if no options are supplied, existing | |
7378 | completion specifications are printed in a way that allows them to | |
7379 | be reused as input. The `-r' option removes a completion | |
7380 | specification for each NAME, or, if no NAMEs are supplied, all | |
ed35cb4a CR |
7381 | completion specifications. The `-E' option indicates that the |
7382 | remaining options and actions should apply to "empty" command | |
7383 | completion; that is, completion attempted on a blank line. | |
bb70624e JA |
7384 | |
7385 | The process of applying these completion specifications when word | |
7386 | completion is attempted is described above (*note Programmable | |
28ef6c31 | 7387 | Completion::). |
bb70624e JA |
7388 | |
7389 | Other options, if specified, have the following meanings. The | |
7390 | arguments to the `-G', `-W', and `-X' options (and, if necessary, | |
7391 | the `-P' and `-S' options) should be quoted to protect them from | |
7392 | expansion before the `complete' builtin is invoked. | |
7393 | ||
28ef6c31 JA |
7394 | `-o COMP-OPTION' |
7395 | The COMP-OPTION controls several aspects of the compspec's | |
7396 | behavior beyond the simple generation of completions. | |
7397 | COMP-OPTION may be one of: | |
7398 | ||
d3a24ed2 CR |
7399 | `bashdefault' |
7400 | Perform the rest of the default Bash completions if the | |
7401 | compspec generates no matches. | |
7402 | ||
28ef6c31 | 7403 | `default' |
7117c2d2 JA |
7404 | Use Readline's default filename completion if the |
7405 | compspec generates no matches. | |
28ef6c31 JA |
7406 | |
7407 | `dirnames' | |
7408 | Perform directory name completion if the compspec | |
7409 | generates no matches. | |
7410 | ||
7411 | `filenames' | |
7412 | Tell Readline that the compspec generates filenames, so | |
d3a24ed2 | 7413 | it can perform any filename-specific processing (like |
28ef6c31 JA |
7414 | adding a slash to directory names or suppressing |
7415 | trailing spaces). This option is intended to be used | |
7416 | with shell functions specified with `-F'. | |
7417 | ||
7117c2d2 JA |
7418 | `nospace' |
7419 | Tell Readline not to append a space (the default) to | |
7420 | words completed at the end of the line. | |
7421 | ||
22e63b05 CR |
7422 | `plusdirs' |
7423 | After any matches defined by the compspec are generated, | |
7424 | directory name completion is attempted and any matches | |
7425 | are added to the results of the other actions. | |
7426 | ||
7427 | ||
bb70624e JA |
7428 | `-A ACTION' |
7429 | The ACTION may be one of the following to generate a list of | |
7430 | possible completions: | |
7431 | ||
7432 | `alias' | |
7433 | Alias names. May also be specified as `-a'. | |
7434 | ||
7435 | `arrayvar' | |
7436 | Array variable names. | |
7437 | ||
7438 | `binding' | |
7439 | Readline key binding names (*note Bindable Readline | |
28ef6c31 | 7440 | Commands::). |
bb70624e JA |
7441 | |
7442 | `builtin' | |
7443 | Names of shell builtin commands. May also be specified | |
7444 | as `-b'. | |
7445 | ||
7446 | `command' | |
7447 | Command names. May also be specified as `-c'. | |
7448 | ||
7449 | `directory' | |
7450 | Directory names. May also be specified as `-d'. | |
7451 | ||
7452 | `disabled' | |
7453 | Names of disabled shell builtins. | |
7454 | ||
7455 | `enabled' | |
7456 | Names of enabled shell builtins. | |
7457 | ||
7458 | `export' | |
7459 | Names of exported shell variables. May also be | |
7460 | specified as `-e'. | |
7461 | ||
7462 | `file' | |
7463 | File names. May also be specified as `-f'. | |
7464 | ||
7465 | `function' | |
7466 | Names of shell functions. | |
7467 | ||
f73dda09 JA |
7468 | `group' |
7469 | Group names. May also be specified as `-g'. | |
7470 | ||
bb70624e JA |
7471 | `helptopic' |
7472 | Help topics as accepted by the `help' builtin (*note | |
28ef6c31 | 7473 | Bash Builtins::). |
bb70624e JA |
7474 | |
7475 | `hostname' | |
7476 | Hostnames, as taken from the file specified by the | |
28ef6c31 | 7477 | `HOSTFILE' shell variable (*note Bash Variables::). |
bb70624e JA |
7478 | |
7479 | `job' | |
7480 | Job names, if job control is active. May also be | |
7481 | specified as `-j'. | |
7482 | ||
7483 | `keyword' | |
7484 | Shell reserved words. May also be specified as `-k'. | |
7485 | ||
7486 | `running' | |
7487 | Names of running jobs, if job control is active. | |
7488 | ||
7117c2d2 JA |
7489 | `service' |
7490 | Service names. May also be specified as `-s'. | |
7491 | ||
bb70624e JA |
7492 | `setopt' |
7493 | Valid arguments for the `-o' option to the `set' builtin | |
28ef6c31 | 7494 | (*note The Set Builtin::). |
bb70624e JA |
7495 | |
7496 | `shopt' | |
7497 | Shell option names as accepted by the `shopt' builtin | |
28ef6c31 | 7498 | (*note Bash Builtins::). |
bb70624e JA |
7499 | |
7500 | `signal' | |
7501 | Signal names. | |
7502 | ||
7503 | `stopped' | |
7504 | Names of stopped jobs, if job control is active. | |
7505 | ||
7506 | `user' | |
7507 | User names. May also be specified as `-u'. | |
7508 | ||
7509 | `variable' | |
7510 | Names of all shell variables. May also be specified as | |
7511 | `-v'. | |
7512 | ||
7513 | `-G GLOBPAT' | |
7514 | The filename expansion pattern GLOBPAT is expanded to generate | |
7515 | the possible completions. | |
7516 | ||
7517 | `-W WORDLIST' | |
7518 | The WORDLIST is split using the characters in the `IFS' | |
7519 | special variable as delimiters, and each resultant word is | |
7520 | expanded. The possible completions are the members of the | |
7521 | resultant list which match the word being completed. | |
7522 | ||
7523 | `-C COMMAND' | |
7524 | COMMAND is executed in a subshell environment, and its output | |
7525 | is used as the possible completions. | |
7526 | ||
7527 | `-F FUNCTION' | |
7528 | The shell function FUNCTION is executed in the current shell | |
7529 | environment. When it finishes, the possible completions are | |
7530 | retrieved from the value of the `COMPREPLY' array variable. | |
7531 | ||
7532 | `-X FILTERPAT' | |
7533 | FILTERPAT is a pattern as used for filename expansion. It is | |
7534 | applied to the list of possible completions generated by the | |
7535 | preceding options and arguments, and each completion matching | |
7536 | FILTERPAT is removed from the list. A leading `!' in | |
7537 | FILTERPAT negates the pattern; in this case, any completion | |
7538 | not matching FILTERPAT is removed. | |
7539 | ||
7540 | `-P PREFIX' | |
7541 | PREFIX is added at the beginning of each possible completion | |
7542 | after all other options have been applied. | |
7543 | ||
7544 | `-S SUFFIX' | |
7545 | SUFFIX is appended to each possible completion after all | |
7546 | other options have been applied. | |
7547 | ||
7548 | The return value is true unless an invalid option is supplied, an | |
7549 | option other than `-p' or `-r' is supplied without a NAME | |
7550 | argument, an attempt is made to remove a completion specification | |
7551 | for a NAME for which no specification exists, or an error occurs | |
7552 | adding a completion specification. | |
7553 | ||
6a8fd0ed CR |
7554 | `compopt' |
7555 | `compopt' [-o OPTION] [+o OPTION] [NAME] | |
7556 | Modify completion options for each NAME according to the OPTIONs, | |
7557 | or for the currently-execution completion if no NAMEs are supplied. | |
7558 | If no OPTIONs are given, display the completion options for each | |
7559 | NAME or the current completion. The possible values of OPTION are | |
7560 | those valid for the `complete' builtin described above. | |
7561 | ||
7562 | The return value is true unless an invalid option is supplied, an | |
7563 | attempt is made to modify the options for a NAME for which no | |
7564 | completion specification exists, or an output error occurs. | |
7565 | ||
7566 | ||
bb70624e | 7567 | \1f |
c2a47ea9 | 7568 | File: bashref.info, Node: Using History Interactively, Next: Installing Bash, Prev: Command Line Editing, Up: Top |
bb70624e | 7569 | |
37c41ab1 CR |
7570 | 9 Using History Interactively |
7571 | ***************************** | |
bb70624e | 7572 | |
37c41ab1 | 7573 | This chapter describes how to use the GNU History Library |
bb70624e JA |
7574 | interactively, from a user's standpoint. It should be considered a |
7575 | user's guide. For information on using the GNU History Library in | |
7576 | other programs, see the GNU Readline Library Manual. | |
7577 | ||
7578 | * Menu: | |
7579 | ||
7580 | * Bash History Facilities:: How Bash lets you manipulate your command | |
7581 | history. | |
7582 | * Bash History Builtins:: The Bash builtin commands that manipulate | |
7583 | the command history. | |
7584 | * History Interaction:: What it feels like using History as a user. | |
7585 | ||
7586 | \1f | |
7587 | File: bashref.info, Node: Bash History Facilities, Next: Bash History Builtins, Up: Using History Interactively | |
7588 | ||
37c41ab1 CR |
7589 | 9.1 Bash History Facilities |
7590 | =========================== | |
bb70624e | 7591 | |
37c41ab1 CR |
7592 | When the `-o history' option to the `set' builtin is enabled (*note The |
7593 | Set Builtin::), the shell provides access to the "command history", the | |
7594 | list of commands previously typed. The value of the `HISTSIZE' shell | |
7595 | variable is used as the number of commands to save in a history list. | |
7596 | The text of the last `$HISTSIZE' commands (default 500) is saved. The | |
7597 | shell stores each command in the history list prior to parameter and | |
7598 | variable expansion but after history expansion is performed, subject to | |
7599 | the values of the shell variables `HISTIGNORE' and `HISTCONTROL'. | |
bb70624e JA |
7600 | |
7601 | When the shell starts up, the history is initialized from the file | |
7602 | named by the `HISTFILE' variable (default `~/.bash_history'). The file | |
7603 | named by the value of `HISTFILE' is truncated, if necessary, to contain | |
7604 | no more than the number of lines specified by the value of the | |
7605 | `HISTFILESIZE' variable. When an interactive shell exits, the last | |
7606 | `$HISTSIZE' lines are copied from the history list to the file named by | |
7607 | `$HISTFILE'. If the `histappend' shell option is set (*note Bash | |
28ef6c31 | 7608 | Builtins::), the lines are appended to the history file, otherwise the |
bb70624e JA |
7609 | history file is overwritten. If `HISTFILE' is unset, or if the history |
7610 | file is unwritable, the history is not saved. After saving the | |
7611 | history, the history file is truncated to contain no more than | |
7612 | `$HISTFILESIZE' lines. If `HISTFILESIZE' is not set, no truncation is | |
7613 | performed. | |
7614 | ||
d3a24ed2 | 7615 | If the `HISTTIMEFORMAT' is set, the time stamp information |
d3ad40de CR |
7616 | associated with each history entry is written to the history file, |
7617 | marked with the history comment character. When the history file is | |
7618 | read, lines beginning with the history comment character followed | |
7619 | immediately by a digit are interpreted as timestamps for the previous | |
7620 | history line. | |
d3a24ed2 | 7621 | |
bb70624e JA |
7622 | The builtin command `fc' may be used to list or edit and re-execute |
7623 | a portion of the history list. The `history' builtin may be used to | |
7624 | display or modify the history list and manipulate the history file. | |
7625 | When using command-line editing, search commands are available in each | |
7626 | editing mode that provide access to the history list (*note Commands | |
28ef6c31 | 7627 | For History::). |
bb70624e JA |
7628 | |
7629 | The shell allows control over which commands are saved on the history | |
7630 | list. The `HISTCONTROL' and `HISTIGNORE' variables may be set to cause | |
7631 | the shell to save only a subset of the commands entered. The `cmdhist' | |
7632 | shell option, if enabled, causes the shell to attempt to save each line | |
7633 | of a multi-line command in the same history entry, adding semicolons | |
7634 | where necessary to preserve syntactic correctness. The `lithist' shell | |
7635 | option causes the shell to save the command with embedded newlines | |
7636 | instead of semicolons. The `shopt' builtin is used to set these | |
7637 | options. *Note Bash Builtins::, for a description of `shopt'. | |
7638 | ||
7639 | \1f | |
7640 | File: bashref.info, Node: Bash History Builtins, Next: History Interaction, Prev: Bash History Facilities, Up: Using History Interactively | |
7641 | ||
37c41ab1 CR |
7642 | 9.2 Bash History Builtins |
7643 | ========================= | |
bb70624e | 7644 | |
37c41ab1 | 7645 | Bash provides two builtin commands which manipulate the history list |
bb70624e JA |
7646 | and history file. |
7647 | ||
7648 | `fc' | |
d3ad40de | 7649 | `fc [-e ENAME] [-lnr] [FIRST] [LAST]' |
bb70624e JA |
7650 | `fc -s [PAT=REP] [COMMAND]' |
7651 | ||
7652 | Fix Command. In the first form, a range of commands from FIRST to | |
7653 | LAST is selected from the history list. Both FIRST and LAST may | |
7654 | be specified as a string (to locate the most recent command | |
7655 | beginning with that string) or as a number (an index into the | |
7656 | history list, where a negative number is used as an offset from the | |
7657 | current command number). If LAST is not specified it is set to | |
7658 | FIRST. If FIRST is not specified it is set to the previous | |
7659 | command for editing and -16 for listing. If the `-l' flag is | |
7660 | given, the commands are listed on standard output. The `-n' flag | |
7661 | suppresses the command numbers when listing. The `-r' flag | |
7662 | reverses the order of the listing. Otherwise, the editor given by | |
7663 | ENAME is invoked on a file containing those commands. If ENAME is | |
7664 | not given, the value of the following variable expansion is used: | |
7665 | `${FCEDIT:-${EDITOR:-vi}}'. This says to use the value of the | |
7666 | `FCEDIT' variable if set, or the value of the `EDITOR' variable if | |
7667 | that is set, or `vi' if neither is set. When editing is complete, | |
7668 | the edited commands are echoed and executed. | |
7669 | ||
7670 | In the second form, COMMAND is re-executed after each instance of | |
7671 | PAT in the selected command is replaced by REP. | |
7672 | ||
7673 | A useful alias to use with the `fc' command is `r='fc -s'', so | |
7674 | that typing `r cc' runs the last command beginning with `cc' and | |
28ef6c31 | 7675 | typing `r' re-executes the last command (*note Aliases::). |
bb70624e JA |
7676 | |
7677 | `history' | |
7678 | history [N] | |
7679 | history -c | |
7680 | history -d OFFSET | |
7681 | history [-anrw] [FILENAME] | |
7682 | history -ps ARG | |
7683 | ||
7684 | With no options, display the history list with line numbers. | |
28ef6c31 | 7685 | Lines prefixed with a `*' have been modified. An argument of N |
d3a24ed2 CR |
7686 | lists only the last N lines. If the shell variable |
7687 | `HISTTIMEFORMAT' is set and not null, it is used as a format | |
7688 | string for STRFTIME to display the time stamp associated with each | |
7689 | displayed history entry. No intervening blank is printed between | |
7690 | the formatted time stamp and the history line. | |
7691 | ||
7692 | Options, if supplied, have the following meanings: | |
bb70624e JA |
7693 | |
7694 | `-c' | |
7695 | Clear the history list. This may be combined with the other | |
7696 | options to replace the history list completely. | |
7697 | ||
7698 | `-d OFFSET' | |
7699 | Delete the history entry at position OFFSET. OFFSET should | |
7700 | be specified as it appears when the history is displayed. | |
7701 | ||
7702 | `-a' | |
7703 | Append the new history lines (history lines entered since the | |
7704 | beginning of the current Bash session) to the history file. | |
7705 | ||
7706 | `-n' | |
7707 | Append the history lines not already read from the history | |
7708 | file to the current history list. These are lines appended | |
7709 | to the history file since the beginning of the current Bash | |
7710 | session. | |
7711 | ||
7712 | `-r' | |
7713 | Read the current history file and append its contents to the | |
7714 | history list. | |
7715 | ||
7716 | `-w' | |
7717 | Write out the current history to the history file. | |
7718 | ||
7719 | `-p' | |
7720 | Perform history substitution on the ARGs and display the | |
7721 | result on the standard output, without storing the results in | |
7722 | the history list. | |
7723 | ||
7724 | `-s' | |
7725 | The ARGs are added to the end of the history list as a single | |
7726 | entry. | |
7727 | ||
761783bf | 7728 | |
bb70624e JA |
7729 | When any of the `-w', `-r', `-a', or `-n' options is used, if |
7730 | FILENAME is given, then it is used as the history file. If not, | |
7731 | then the value of the `HISTFILE' variable is used. | |
7732 | ||
761783bf | 7733 | |
bb70624e JA |
7734 | \1f |
7735 | File: bashref.info, Node: History Interaction, Prev: Bash History Builtins, Up: Using History Interactively | |
ccc6cda3 | 7736 | |
37c41ab1 CR |
7737 | 9.3 History Expansion |
7738 | ===================== | |
ccc6cda3 | 7739 | |
37c41ab1 CR |
7740 | The History library provides a history expansion feature that is similar |
7741 | to the history expansion provided by `csh'. This section describes the | |
7742 | syntax used to manipulate the history information. | |
ccc6cda3 | 7743 | |
bb70624e JA |
7744 | History expansions introduce words from the history list into the |
7745 | input stream, making it easy to repeat commands, insert the arguments | |
7746 | to a previous command into the current input line, or fix errors in | |
7747 | previous commands quickly. | |
ccc6cda3 | 7748 | |
bb70624e JA |
7749 | History expansion takes place in two parts. The first is to |
7750 | determine which line from the history list should be used during | |
7751 | substitution. The second is to select portions of that line for | |
7752 | inclusion into the current one. The line selected from the history is | |
7753 | called the "event", and the portions of that line that are acted upon | |
7754 | are called "words". Various "modifiers" are available to manipulate | |
7755 | the selected words. The line is broken into words in the same fashion | |
7756 | that Bash does, so that several words surrounded by quotes are | |
7757 | considered one word. History expansions are introduced by the | |
7758 | appearance of the history expansion character, which is `!' by default. | |
7759 | Only `\' and `'' may be used to escape the history expansion character. | |
7760 | ||
7761 | Several shell options settable with the `shopt' builtin (*note Bash | |
28ef6c31 | 7762 | Builtins::) may be used to tailor the behavior of history expansion. |
bb70624e JA |
7763 | If the `histverify' shell option is enabled, and Readline is being |
7764 | used, history substitutions are not immediately passed to the shell | |
7765 | parser. Instead, the expanded line is reloaded into the Readline | |
7766 | editing buffer for further modification. If Readline is being used, | |
7767 | and the `histreedit' shell option is enabled, a failed history | |
7768 | expansion will be reloaded into the Readline editing buffer for | |
7769 | correction. The `-p' option to the `history' builtin command may be | |
7770 | used to see what a history expansion will do before using it. The `-s' | |
7771 | option to the `history' builtin may be used to add commands to the end | |
7772 | of the history list without actually executing them, so that they are | |
7773 | available for subsequent recall. This is most useful in conjunction | |
7774 | with Readline. | |
7775 | ||
7776 | The shell allows control of the various characters used by the | |
d3ad40de CR |
7777 | history expansion mechanism with the `histchars' variable, as explained |
7778 | above (*note Bash Variables::). The shell uses the history comment | |
7779 | character to mark history timestamps when writing the history file. | |
bb70624e JA |
7780 | |
7781 | * Menu: | |
7782 | ||
7783 | * Event Designators:: How to specify which history line to use. | |
7784 | * Word Designators:: Specifying which words are of interest. | |
7785 | * Modifiers:: Modifying the results of substitution. | |
ccc6cda3 JA |
7786 | |
7787 | \1f | |
bb70624e | 7788 | File: bashref.info, Node: Event Designators, Next: Word Designators, Up: History Interaction |
ccc6cda3 | 7789 | |
37c41ab1 CR |
7790 | 9.3.1 Event Designators |
7791 | ----------------------- | |
ccc6cda3 | 7792 | |
37c41ab1 CR |
7793 | An event designator is a reference to a command line entry in the |
7794 | history list. | |
ccc6cda3 | 7795 | |
bb70624e JA |
7796 | `!' |
7797 | Start a history substitution, except when followed by a space, tab, | |
d3a24ed2 CR |
7798 | the end of the line, `=' or `(' (when the `extglob' shell option |
7799 | is enabled using the `shopt' builtin). | |
ccc6cda3 | 7800 | |
bb70624e JA |
7801 | `!N' |
7802 | Refer to command line N. | |
ccc6cda3 | 7803 | |
bb70624e JA |
7804 | `!-N' |
7805 | Refer to the command N lines back. | |
ccc6cda3 | 7806 | |
bb70624e JA |
7807 | `!!' |
7808 | Refer to the previous command. This is a synonym for `!-1'. | |
ccc6cda3 | 7809 | |
bb70624e JA |
7810 | `!STRING' |
7811 | Refer to the most recent command starting with STRING. | |
ccc6cda3 | 7812 | |
bb70624e JA |
7813 | `!?STRING[?]' |
7814 | Refer to the most recent command containing STRING. The trailing | |
7815 | `?' may be omitted if the STRING is followed immediately by a | |
7816 | newline. | |
ccc6cda3 | 7817 | |
bb70624e JA |
7818 | `^STRING1^STRING2^' |
7819 | Quick Substitution. Repeat the last command, replacing STRING1 | |
7820 | with STRING2. Equivalent to `!!:s/STRING1/STRING2/'. | |
7821 | ||
7822 | `!#' | |
7823 | The entire command line typed so far. | |
ccc6cda3 | 7824 | |
761783bf | 7825 | |
ccc6cda3 | 7826 | \1f |
bb70624e | 7827 | File: bashref.info, Node: Word Designators, Next: Modifiers, Prev: Event Designators, Up: History Interaction |
ccc6cda3 | 7828 | |
37c41ab1 CR |
7829 | 9.3.2 Word Designators |
7830 | ---------------------- | |
ccc6cda3 | 7831 | |
37c41ab1 | 7832 | Word designators are used to select desired words from the event. A |
bb70624e JA |
7833 | `:' separates the event specification from the word designator. It may |
7834 | be omitted if the word designator begins with a `^', `$', `*', `-', or | |
7835 | `%'. Words are numbered from the beginning of the line, with the first | |
7836 | word being denoted by 0 (zero). Words are inserted into the current | |
7837 | line separated by single spaces. | |
ccc6cda3 | 7838 | |
bb70624e | 7839 | For example, |
ccc6cda3 | 7840 | |
bb70624e JA |
7841 | `!!' |
7842 | designates the preceding command. When you type this, the | |
7843 | preceding command is repeated in toto. | |
ccc6cda3 | 7844 | |
bb70624e JA |
7845 | `!!:$' |
7846 | designates the last argument of the preceding command. This may be | |
7847 | shortened to `!$'. | |
ccc6cda3 | 7848 | |
bb70624e JA |
7849 | `!fi:2' |
7850 | designates the second argument of the most recent command starting | |
7851 | with the letters `fi'. | |
ccc6cda3 | 7852 | |
bb70624e | 7853 | Here are the word designators: |
ccc6cda3 | 7854 | |
bb70624e JA |
7855 | `0 (zero)' |
7856 | The `0'th word. For many applications, this is the command word. | |
ccc6cda3 | 7857 | |
bb70624e JA |
7858 | `N' |
7859 | The Nth word. | |
ccc6cda3 | 7860 | |
bb70624e JA |
7861 | `^' |
7862 | The first argument; that is, word 1. | |
ccc6cda3 | 7863 | |
bb70624e JA |
7864 | `$' |
7865 | The last argument. | |
ccc6cda3 | 7866 | |
bb70624e JA |
7867 | `%' |
7868 | The word matched by the most recent `?STRING?' search. | |
ccc6cda3 | 7869 | |
bb70624e JA |
7870 | `X-Y' |
7871 | A range of words; `-Y' abbreviates `0-Y'. | |
ccc6cda3 | 7872 | |
bb70624e JA |
7873 | `*' |
7874 | All of the words, except the `0'th. This is a synonym for `1-$'. | |
7875 | It is not an error to use `*' if there is just one word in the | |
7876 | event; the empty string is returned in that case. | |
7877 | ||
7878 | `X*' | |
7879 | Abbreviates `X-$' | |
7880 | ||
7881 | `X-' | |
7882 | Abbreviates `X-$' like `X*', but omits the last word. | |
7883 | ||
761783bf | 7884 | |
bb70624e JA |
7885 | If a word designator is supplied without an event specification, the |
7886 | previous command is used as the event. | |
ccc6cda3 JA |
7887 | |
7888 | \1f | |
bb70624e | 7889 | File: bashref.info, Node: Modifiers, Prev: Word Designators, Up: History Interaction |
ccc6cda3 | 7890 | |
37c41ab1 CR |
7891 | 9.3.3 Modifiers |
7892 | --------------- | |
ccc6cda3 | 7893 | |
37c41ab1 | 7894 | After the optional word designator, you can add a sequence of one or |
bb70624e | 7895 | more of the following modifiers, each preceded by a `:'. |
ccc6cda3 | 7896 | |
bb70624e JA |
7897 | `h' |
7898 | Remove a trailing pathname component, leaving only the head. | |
ccc6cda3 | 7899 | |
bb70624e | 7900 | `t' |
d3ad40de | 7901 | Remove all leading pathname components, leaving the tail. |
bb70624e JA |
7902 | |
7903 | `r' | |
7904 | Remove a trailing suffix of the form `.SUFFIX', leaving the | |
7905 | basename. | |
7906 | ||
7907 | `e' | |
7908 | Remove all but the trailing suffix. | |
7909 | ||
7910 | `p' | |
7911 | Print the new command but do not execute it. | |
7912 | ||
7913 | `q' | |
7914 | Quote the substituted words, escaping further substitutions. | |
7915 | ||
7916 | `x' | |
7917 | Quote the substituted words as with `q', but break into words at | |
7918 | spaces, tabs, and newlines. | |
7919 | ||
7920 | `s/OLD/NEW/' | |
7921 | Substitute NEW for the first occurrence of OLD in the event line. | |
7922 | Any delimiter may be used in place of `/'. The delimiter may be | |
7923 | quoted in OLD and NEW with a single backslash. If `&' appears in | |
7924 | NEW, it is replaced by OLD. A single backslash will quote the | |
7925 | `&'. The final delimiter is optional if it is the last character | |
7926 | on the input line. | |
7927 | ||
7928 | `&' | |
7929 | Repeat the previous substitution. | |
7930 | ||
7931 | `g' | |
d3a24ed2 | 7932 | `a' |
bb70624e JA |
7933 | Cause changes to be applied over the entire event line. Used in |
7934 | conjunction with `s', as in `gs/OLD/NEW/', or with `&'. | |
7935 | ||
d3a24ed2 CR |
7936 | `G' |
7937 | Apply the following `s' modifier once to each word in the event. | |
7938 | ||
761783bf | 7939 | |
bb70624e | 7940 | \1f |
c2a47ea9 | 7941 | File: bashref.info, Node: Installing Bash, Next: Reporting Bugs, Prev: Using History Interactively, Up: Top |
bb70624e | 7942 | |
37c41ab1 CR |
7943 | 10 Installing Bash |
7944 | ****************** | |
b72432fd | 7945 | |
37c41ab1 | 7946 | This chapter provides basic instructions for installing Bash on the |
bb70624e JA |
7947 | various supported platforms. The distribution supports the GNU |
7948 | operating systems, nearly every version of Unix, and several non-Unix | |
7949 | systems such as BeOS and Interix. Other independent ports exist for | |
d3a24ed2 | 7950 | MS-DOS, OS/2, and Windows platforms. |
ccc6cda3 | 7951 | |
bb70624e | 7952 | * Menu: |
ccc6cda3 | 7953 | |
bb70624e | 7954 | * Basic Installation:: Installation instructions. |
bb70624e JA |
7955 | * Compilers and Options:: How to set special options for various |
7956 | systems. | |
bb70624e JA |
7957 | * Compiling For Multiple Architectures:: How to compile Bash for more |
7958 | than one kind of system from | |
7959 | the same source tree. | |
bb70624e | 7960 | * Installation Names:: How to set the various paths used by the installation. |
bb70624e | 7961 | * Specifying the System Type:: How to configure Bash for a particular system. |
bb70624e JA |
7962 | * Sharing Defaults:: How to share default configuration values among GNU |
7963 | programs. | |
bb70624e | 7964 | * Operation Controls:: Options recognized by the configuration program. |
bb70624e JA |
7965 | * Optional Features:: How to enable and disable optional features when |
7966 | building Bash. | |
ccc6cda3 | 7967 | |
bb70624e JA |
7968 | \1f |
7969 | File: bashref.info, Node: Basic Installation, Next: Compilers and Options, Up: Installing Bash | |
ccc6cda3 | 7970 | |
37c41ab1 CR |
7971 | 10.1 Basic Installation |
7972 | ======================= | |
ccc6cda3 | 7973 | |
37c41ab1 | 7974 | These are installation instructions for Bash. |
ccc6cda3 | 7975 | |
bb70624e | 7976 | The simplest way to compile Bash is: |
ccc6cda3 | 7977 | |
bb70624e JA |
7978 | 1. `cd' to the directory containing the source code and type |
7979 | `./configure' to configure Bash for your system. If you're using | |
7980 | `csh' on an old version of System V, you might need to type `sh | |
7981 | ./configure' instead to prevent `csh' from trying to execute | |
7982 | `configure' itself. | |
ccc6cda3 | 7983 | |
bb70624e JA |
7984 | Running `configure' takes some time. While running, it prints |
7985 | messages telling which features it is checking for. | |
ccc6cda3 | 7986 | |
bb70624e JA |
7987 | 2. Type `make' to compile Bash and build the `bashbug' bug reporting |
7988 | script. | |
ccc6cda3 | 7989 | |
bb70624e | 7990 | 3. Optionally, type `make tests' to run the Bash test suite. |
ccc6cda3 | 7991 | |
bb70624e JA |
7992 | 4. Type `make install' to install `bash' and `bashbug'. This will |
7993 | also install the manual pages and Info file. | |
ccc6cda3 | 7994 | |
ccc6cda3 | 7995 | |
bb70624e JA |
7996 | The `configure' shell script attempts to guess correct values for |
7997 | various system-dependent variables used during compilation. It uses | |
7998 | those values to create a `Makefile' in each directory of the package | |
7999 | (the top directory, the `builtins', `doc', and `support' directories, | |
8000 | each directory under `lib', and several others). It also creates a | |
8001 | `config.h' file containing system-dependent definitions. Finally, it | |
8002 | creates a shell script named `config.status' that you can run in the | |
8003 | future to recreate the current configuration, a file `config.cache' | |
8004 | that saves the results of its tests to speed up reconfiguring, and a | |
8005 | file `config.log' containing compiler output (useful mainly for | |
8006 | debugging `configure'). If at some point `config.cache' contains | |
8007 | results you don't want to keep, you may remove or edit it. | |
ccc6cda3 | 8008 | |
bb70624e JA |
8009 | To find out more about the options and arguments that the |
8010 | `configure' script understands, type | |
ccc6cda3 | 8011 | |
bb70624e | 8012 | bash-2.04$ ./configure --help |
ccc6cda3 | 8013 | |
bb70624e | 8014 | at the Bash prompt in your Bash source directory. |
ccc6cda3 | 8015 | |
bb70624e JA |
8016 | If you need to do unusual things to compile Bash, please try to |
8017 | figure out how `configure' could check whether or not to do them, and | |
8018 | mail diffs or instructions to <bash-maintainers@gnu.org> so they can be | |
8019 | considered for the next release. | |
ccc6cda3 | 8020 | |
bb70624e JA |
8021 | The file `configure.in' is used to create `configure' by a program |
8022 | called Autoconf. You only need `configure.in' if you want to change it | |
8023 | or regenerate `configure' using a newer version of Autoconf. If you do | |
f73dda09 | 8024 | this, make sure you are using Autoconf version 2.50 or newer. |
ccc6cda3 | 8025 | |
bb70624e JA |
8026 | You can remove the program binaries and object files from the source |
8027 | code directory by typing `make clean'. To also remove the files that | |
8028 | `configure' created (so you can compile Bash for a different kind of | |
8029 | computer), type `make distclean'. | |
ccc6cda3 | 8030 | |
bb70624e JA |
8031 | \1f |
8032 | File: bashref.info, Node: Compilers and Options, Next: Compiling For Multiple Architectures, Prev: Basic Installation, Up: Installing Bash | |
ccc6cda3 | 8033 | |
37c41ab1 CR |
8034 | 10.2 Compilers and Options |
8035 | ========================== | |
ccc6cda3 | 8036 | |
37c41ab1 | 8037 | Some systems require unusual options for compilation or linking that |
bb70624e JA |
8038 | the `configure' script does not know about. You can give `configure' |
8039 | initial values for variables by setting them in the environment. Using | |
8040 | a Bourne-compatible shell, you can do that on the command line like | |
8041 | this: | |
ccc6cda3 | 8042 | |
bb70624e | 8043 | CC=c89 CFLAGS=-O2 LIBS=-lposix ./configure |
ccc6cda3 | 8044 | |
bb70624e | 8045 | On systems that have the `env' program, you can do it like this: |
cce855bc | 8046 | |
bb70624e | 8047 | env CPPFLAGS=-I/usr/local/include LDFLAGS=-s ./configure |
b72432fd | 8048 | |
bb70624e | 8049 | The configuration process uses GCC to build Bash if it is available. |
ccc6cda3 | 8050 | |
bb70624e JA |
8051 | \1f |
8052 | File: bashref.info, Node: Compiling For Multiple Architectures, Next: Installation Names, Prev: Compilers and Options, Up: Installing Bash | |
ccc6cda3 | 8053 | |
37c41ab1 CR |
8054 | 10.3 Compiling For Multiple Architectures |
8055 | ========================================= | |
ccc6cda3 | 8056 | |
37c41ab1 | 8057 | You can compile Bash for more than one kind of computer at the same |
bb70624e JA |
8058 | time, by placing the object files for each architecture in their own |
8059 | directory. To do this, you must use a version of `make' that supports | |
8060 | the `VPATH' variable, such as GNU `make'. `cd' to the directory where | |
8061 | you want the object files and executables to go and run the `configure' | |
8062 | script from the source directory. You may need to supply the | |
8063 | `--srcdir=PATH' argument to tell `configure' where the source files | |
8064 | are. `configure' automatically checks for the source code in the | |
8065 | directory that `configure' is in and in `..'. | |
ccc6cda3 | 8066 | |
bb70624e JA |
8067 | If you have to use a `make' that does not supports the `VPATH' |
8068 | variable, you can compile Bash for one architecture at a time in the | |
8069 | source code directory. After you have installed Bash for one | |
8070 | architecture, use `make distclean' before reconfiguring for another | |
8071 | architecture. | |
ccc6cda3 | 8072 | |
bb70624e JA |
8073 | Alternatively, if your system supports symbolic links, you can use |
8074 | the `support/mkclone' script to create a build tree which has symbolic | |
8075 | links back to each file in the source directory. Here's an example | |
8076 | that creates a build directory in the current directory from a source | |
8077 | directory `/usr/gnu/src/bash-2.0': | |
ccc6cda3 | 8078 | |
bb70624e | 8079 | bash /usr/gnu/src/bash-2.0/support/mkclone -s /usr/gnu/src/bash-2.0 . |
ccc6cda3 | 8080 | |
bb70624e JA |
8081 | The `mkclone' script requires Bash, so you must have already built Bash |
8082 | for at least one architecture before you can create build directories | |
8083 | for other architectures. | |
ccc6cda3 | 8084 | |
bb70624e JA |
8085 | \1f |
8086 | File: bashref.info, Node: Installation Names, Next: Specifying the System Type, Prev: Compiling For Multiple Architectures, Up: Installing Bash | |
ccc6cda3 | 8087 | |
37c41ab1 CR |
8088 | 10.4 Installation Names |
8089 | ======================= | |
ccc6cda3 | 8090 | |
37c41ab1 | 8091 | By default, `make install' will install into `/usr/local/bin', |
bb70624e | 8092 | `/usr/local/man', etc. You can specify an installation prefix other |
f73dda09 JA |
8093 | than `/usr/local' by giving `configure' the option `--prefix=PATH', or |
8094 | by specifying a value for the `DESTDIR' `make' variable when running | |
8095 | `make install'. | |
ccc6cda3 | 8096 | |
bb70624e JA |
8097 | You can specify separate installation prefixes for |
8098 | architecture-specific files and architecture-independent files. If you | |
8099 | give `configure' the option `--exec-prefix=PATH', `make install' will | |
8100 | use PATH as the prefix for installing programs and libraries. | |
8101 | Documentation and other data files will still use the regular prefix. | |
ccc6cda3 JA |
8102 | |
8103 | \1f | |
bb70624e | 8104 | File: bashref.info, Node: Specifying the System Type, Next: Sharing Defaults, Prev: Installation Names, Up: Installing Bash |
ccc6cda3 | 8105 | |
37c41ab1 CR |
8106 | 10.5 Specifying the System Type |
8107 | =============================== | |
ccc6cda3 | 8108 | |
37c41ab1 | 8109 | There may be some features `configure' can not figure out |
f73dda09 | 8110 | automatically, but need to determine by the type of host Bash will run |
bb70624e JA |
8111 | on. Usually `configure' can figure that out, but if it prints a |
8112 | message saying it can not guess the host type, give it the | |
8113 | `--host=TYPE' option. `TYPE' can either be a short name for the system | |
8114 | type, such as `sun4', or a canonical name with three fields: | |
f73dda09 | 8115 | `CPU-COMPANY-SYSTEM' (e.g., `i386-unknown-freebsd4.2'). |
ccc6cda3 | 8116 | |
bb70624e JA |
8117 | See the file `support/config.sub' for the possible values of each |
8118 | field. | |
ccc6cda3 | 8119 | |
bb70624e JA |
8120 | \1f |
8121 | File: bashref.info, Node: Sharing Defaults, Next: Operation Controls, Prev: Specifying the System Type, Up: Installing Bash | |
8122 | ||
37c41ab1 CR |
8123 | 10.6 Sharing Defaults |
8124 | ===================== | |
bb70624e | 8125 | |
37c41ab1 CR |
8126 | If you want to set default values for `configure' scripts to share, you |
8127 | can create a site shell script called `config.site' that gives default | |
8128 | values for variables like `CC', `cache_file', and `prefix'. `configure' | |
8129 | looks for `PREFIX/share/config.site' if it exists, then | |
bb70624e JA |
8130 | `PREFIX/etc/config.site' if it exists. Or, you can set the |
8131 | `CONFIG_SITE' environment variable to the location of the site script. | |
8132 | A warning: the Bash `configure' looks for a site script, but not all | |
8133 | `configure' scripts do. | |
ccc6cda3 JA |
8134 | |
8135 | \1f | |
bb70624e | 8136 | File: bashref.info, Node: Operation Controls, Next: Optional Features, Prev: Sharing Defaults, Up: Installing Bash |
ccc6cda3 | 8137 | |
37c41ab1 CR |
8138 | 10.7 Operation Controls |
8139 | ======================= | |
ccc6cda3 | 8140 | |
37c41ab1 | 8141 | `configure' recognizes the following options to control how it operates. |
ccc6cda3 | 8142 | |
bb70624e JA |
8143 | `--cache-file=FILE' |
8144 | Use and save the results of the tests in FILE instead of | |
8145 | `./config.cache'. Set FILE to `/dev/null' to disable caching, for | |
8146 | debugging `configure'. | |
ccc6cda3 | 8147 | |
bb70624e JA |
8148 | `--help' |
8149 | Print a summary of the options to `configure', and exit. | |
ccc6cda3 | 8150 | |
bb70624e JA |
8151 | `--quiet' |
8152 | `--silent' | |
8153 | `-q' | |
8154 | Do not print messages saying which checks are being made. | |
ccc6cda3 | 8155 | |
bb70624e JA |
8156 | `--srcdir=DIR' |
8157 | Look for the Bash source code in directory DIR. Usually | |
8158 | `configure' can determine that directory automatically. | |
ccc6cda3 | 8159 | |
bb70624e JA |
8160 | `--version' |
8161 | Print the version of Autoconf used to generate the `configure' | |
8162 | script, and exit. | |
ccc6cda3 | 8163 | |
bb70624e JA |
8164 | `configure' also accepts some other, not widely used, boilerplate |
8165 | options. `configure --help' prints the complete list. | |
ccc6cda3 | 8166 | |
bb70624e JA |
8167 | \1f |
8168 | File: bashref.info, Node: Optional Features, Prev: Operation Controls, Up: Installing Bash | |
ccc6cda3 | 8169 | |
37c41ab1 CR |
8170 | 10.8 Optional Features |
8171 | ====================== | |
ccc6cda3 | 8172 | |
37c41ab1 CR |
8173 | The Bash `configure' has a number of `--enable-FEATURE' options, where |
8174 | FEATURE indicates an optional part of Bash. There are also several | |
8175 | `--with-PACKAGE' options, where PACKAGE is something like `bash-malloc' | |
8176 | or `purify'. To turn off the default use of a package, use | |
8177 | `--without-PACKAGE'. To configure Bash without a feature that is | |
bb70624e | 8178 | enabled by default, use `--disable-FEATURE'. |
ccc6cda3 | 8179 | |
bb70624e JA |
8180 | Here is a complete list of the `--enable-' and `--with-' options |
8181 | that the Bash `configure' recognizes. | |
ccc6cda3 | 8182 | |
bb70624e JA |
8183 | `--with-afs' |
8184 | Define if you are using the Andrew File System from Transarc. | |
ccc6cda3 | 8185 | |
bb70624e | 8186 | `--with-bash-malloc' |
1c72c0cd CR |
8187 | Use the Bash version of `malloc' in the directory `lib/malloc'. |
8188 | This is not the same `malloc' that appears in GNU libc, but an | |
8189 | older version originally derived from the 4.2 BSD `malloc'. This | |
8190 | `malloc' is very fast, but wastes some space on each allocation. | |
8191 | This option is enabled by default. The `NOTES' file contains a | |
8192 | list of systems for which this should be turned off, and | |
8193 | `configure' disables this option automatically for a number of | |
8194 | systems. | |
ccc6cda3 | 8195 | |
bb70624e JA |
8196 | `--with-curses' |
8197 | Use the curses library instead of the termcap library. This should | |
8198 | be supplied if your system has an inadequate or incomplete termcap | |
8199 | database. | |
ccc6cda3 | 8200 | |
bb70624e JA |
8201 | `--with-gnu-malloc' |
8202 | A synonym for `--with-bash-malloc'. | |
ccc6cda3 | 8203 | |
f73dda09 | 8204 | `--with-installed-readline[=PREFIX]' |
bb70624e JA |
8205 | Define this to make Bash link with a locally-installed version of |
8206 | Readline rather than the version in `lib/readline'. This works | |
01ed5ba4 | 8207 | only with Readline 5.0 and later versions. If PREFIX is `yes' or |
f73dda09 JA |
8208 | not supplied, `configure' uses the values of the make variables |
8209 | `includedir' and `libdir', which are subdirectories of `prefix' by | |
8210 | default, to find the installed version of Readline if it is not in | |
8211 | the standard system include and library directories. If PREFIX is | |
8212 | `no', Bash links with the version in `lib/readline'. If PREFIX is | |
8213 | set to any other value, `configure' treats it as a directory | |
8214 | pathname and looks for the installed version of Readline in | |
8215 | subdirectories of that directory (include files in | |
8216 | PREFIX/`include' and the library in PREFIX/`lib'). | |
ccc6cda3 | 8217 | |
bb70624e JA |
8218 | `--with-purify' |
8219 | Define this to use the Purify memory allocation checker from | |
8220 | Rational Software. | |
ccc6cda3 | 8221 | |
bb70624e JA |
8222 | `--enable-minimal-config' |
8223 | This produces a shell with minimal features, close to the | |
8224 | historical Bourne shell. | |
ccc6cda3 | 8225 | |
bb70624e JA |
8226 | There are several `--enable-' options that alter how Bash is |
8227 | compiled and linked, rather than changing run-time features. | |
ccc6cda3 | 8228 | |
f73dda09 JA |
8229 | `--enable-largefile' |
8230 | Enable support for large files | |
8231 | (http://www.sas.com/standards/large_file/x_open.20Mar96.html) if | |
8232 | the operating system requires special compiler options to build | |
7117c2d2 JA |
8233 | programs which can access large files. This is enabled by |
8234 | default, if the operating system provides large file support. | |
f73dda09 | 8235 | |
bb70624e JA |
8236 | `--enable-profiling' |
8237 | This builds a Bash binary that produces profiling information to be | |
8238 | processed by `gprof' each time it is executed. | |
cce855bc | 8239 | |
bb70624e JA |
8240 | `--enable-static-link' |
8241 | This causes Bash to be linked statically, if `gcc' is being used. | |
8242 | This could be used to build a version to use as root's shell. | |
d166f048 | 8243 | |
bb70624e JA |
8244 | The `minimal-config' option can be used to disable all of the |
8245 | following options, but it is processed first, so individual options may | |
8246 | be enabled using `enable-FEATURE'. | |
d166f048 | 8247 | |
bb70624e JA |
8248 | All of the following options except for `disabled-builtins' and |
8249 | `xpg-echo-default' are enabled by default, unless the operating system | |
8250 | does not provide the necessary support. | |
ccc6cda3 | 8251 | |
bb70624e JA |
8252 | `--enable-alias' |
8253 | Allow alias expansion and include the `alias' and `unalias' | |
28ef6c31 | 8254 | builtins (*note Aliases::). |
ccc6cda3 | 8255 | |
bb70624e JA |
8256 | `--enable-arith-for-command' |
8257 | Include support for the alternate form of the `for' command that | |
8258 | behaves like the C language `for' statement (*note Looping | |
28ef6c31 | 8259 | Constructs::). |
ccc6cda3 | 8260 | |
bb70624e JA |
8261 | `--enable-array-variables' |
8262 | Include support for one-dimensional array shell variables (*note | |
28ef6c31 | 8263 | Arrays::). |
ccc6cda3 | 8264 | |
bb70624e JA |
8265 | `--enable-bang-history' |
8266 | Include support for `csh'-like history substitution (*note History | |
28ef6c31 | 8267 | Interaction::). |
ccc6cda3 | 8268 | |
bb70624e JA |
8269 | `--enable-brace-expansion' |
8270 | Include `csh'-like brace expansion ( `b{a,b}c' ==> `bac bbc' ). | |
6a8fd0ed | 8271 | See *note Brace Expansion::, for a complete description. |
ccc6cda3 | 8272 | |
bb70624e JA |
8273 | `--enable-command-timing' |
8274 | Include support for recognizing `time' as a reserved word and for | |
8275 | displaying timing statistics for the pipeline following `time' | |
28ef6c31 | 8276 | (*note Pipelines::). This allows pipelines as well as shell |
bb70624e | 8277 | builtins and functions to be timed. |
ccc6cda3 | 8278 | |
bb70624e | 8279 | `--enable-cond-command' |
5e13499c CR |
8280 | Include support for the `[[' conditional command. (*note |
8281 | Conditional Constructs::). | |
8282 | ||
8283 | `--enable-cond-regexp' | |
8284 | Include support for matching POSIX regular expressions using the | |
8285 | `=~' binary operator in the `[[' conditional command. (*note | |
28ef6c31 | 8286 | Conditional Constructs::). |
ccc6cda3 | 8287 | |
01ed5ba4 CR |
8288 | `--enable-debugger' |
8289 | Include support for the bash debugger (distributed separately). | |
8290 | ||
bb70624e JA |
8291 | `--enable-directory-stack' |
8292 | Include support for a `csh'-like directory stack and the `pushd', | |
28ef6c31 | 8293 | `popd', and `dirs' builtins (*note The Directory Stack::). |
ccc6cda3 | 8294 | |
bb70624e JA |
8295 | `--enable-disabled-builtins' |
8296 | Allow builtin commands to be invoked via `builtin xxx' even after | |
6a8fd0ed | 8297 | `xxx' has been disabled using `enable -n xxx'. See *note Bash |
bb70624e JA |
8298 | Builtins::, for details of the `builtin' and `enable' builtin |
8299 | commands. | |
ccc6cda3 | 8300 | |
bb70624e JA |
8301 | `--enable-dparen-arithmetic' |
8302 | Include support for the `((...))' command (*note Conditional | |
28ef6c31 | 8303 | Constructs::). |
ccc6cda3 | 8304 | |
bb70624e JA |
8305 | `--enable-extended-glob' |
8306 | Include support for the extended pattern matching features | |
6a8fd0ed | 8307 | described above under *note Pattern Matching::. |
ccc6cda3 | 8308 | |
bb70624e JA |
8309 | `--enable-help-builtin' |
8310 | Include the `help' builtin, which displays help on shell builtins | |
28ef6c31 | 8311 | and variables (*note Bash Builtins::). |
ccc6cda3 | 8312 | |
bb70624e JA |
8313 | `--enable-history' |
8314 | Include command history and the `fc' and `history' builtin | |
28ef6c31 | 8315 | commands (*note Bash History Facilities::). |
ccc6cda3 | 8316 | |
bb70624e | 8317 | `--enable-job-control' |
28ef6c31 | 8318 | This enables the job control features (*note Job Control::), if |
bb70624e | 8319 | the operating system supports them. |
ccc6cda3 | 8320 | |
d3a24ed2 CR |
8321 | `--enable-multibyte' |
8322 | This enables support for multibyte characters if the operating | |
8323 | system provides the necessary support. | |
8324 | ||
bb70624e JA |
8325 | `--enable-net-redirections' |
8326 | This enables the special handling of filenames of the form | |
8327 | `/dev/tcp/HOST/PORT' and `/dev/udp/HOST/PORT' when used in | |
28ef6c31 | 8328 | redirections (*note Redirections::). |
ccc6cda3 | 8329 | |
bb70624e | 8330 | `--enable-process-substitution' |
28ef6c31 JA |
8331 | This enables process substitution (*note Process Substitution::) if |
8332 | the operating system provides the necessary support. | |
ccc6cda3 | 8333 | |
01ed5ba4 CR |
8334 | `--enable-progcomp' |
8335 | Enable the programmable completion facilities (*note Programmable | |
8336 | Completion::). If Readline is not enabled, this option has no | |
8337 | effect. | |
8338 | ||
bb70624e JA |
8339 | `--enable-prompt-string-decoding' |
8340 | Turn on the interpretation of a number of backslash-escaped | |
8341 | characters in the `$PS1', `$PS2', `$PS3', and `$PS4' prompt | |
6a8fd0ed | 8342 | strings. See *note Printing a Prompt::, for a complete list of |
bb70624e | 8343 | prompt string escape sequences. |
ccc6cda3 | 8344 | |
bb70624e JA |
8345 | `--enable-readline' |
8346 | Include support for command-line editing and history with the Bash | |
28ef6c31 | 8347 | version of the Readline library (*note Command Line Editing::). |
ccc6cda3 | 8348 | |
bb70624e JA |
8349 | `--enable-restricted' |
8350 | Include support for a "restricted shell". If this is enabled, | |
6a8fd0ed | 8351 | Bash, when called as `rbash', enters a restricted mode. See *note |
bb70624e | 8352 | The Restricted Shell::, for a description of restricted mode. |
ccc6cda3 | 8353 | |
bb70624e JA |
8354 | `--enable-select' |
8355 | Include the `select' builtin, which allows the generation of simple | |
28ef6c31 | 8356 | menus (*note Conditional Constructs::). |
ccc6cda3 | 8357 | |
01ed5ba4 CR |
8358 | `--enable-separate-helpfiles' |
8359 | Use external files for the documentation displayed by the `help' | |
8360 | builtin instead of storing the text internally. | |
8361 | ||
8362 | `--enable-single-help-strings' | |
8363 | Store the text displayed by the `help' builtin as a single string | |
8364 | for each help topic. This aids in translating the text to | |
8365 | different languages. You may need to disable this if your | |
8366 | compiler cannot handle very long string literals. | |
8367 | ||
1c72c0cd CR |
8368 | `--enable-strict-posix-default' |
8369 | Make Bash POSIX-conformant by default (*note Bash POSIX Mode::). | |
8370 | ||
bb70624e JA |
8371 | `--enable-usg-echo-default' |
8372 | A synonym for `--enable-xpg-echo-default'. | |
ccc6cda3 | 8373 | |
bb70624e JA |
8374 | `--enable-xpg-echo-default' |
8375 | Make the `echo' builtin expand backslash-escaped characters by | |
8376 | default, without requiring the `-e' option. This sets the default | |
8377 | value of the `xpg_echo' shell option to `on', which makes the Bash | |
8378 | `echo' behave more like the version specified in the Single Unix | |
01ed5ba4 | 8379 | Specification, version 3. *Note Bash Builtins::, for a |
bb70624e | 8380 | description of the escape sequences that `echo' recognizes. |
ccc6cda3 | 8381 | |
761783bf | 8382 | |
bb70624e JA |
8383 | The file `config-top.h' contains C Preprocessor `#define' statements |
8384 | for options which are not settable from `configure'. Some of these are | |
8385 | not meant to be changed; beware of the consequences if you do. Read | |
8386 | the comments associated with each definition for more information about | |
8387 | its effect. | |
ccc6cda3 | 8388 | |
bb70624e JA |
8389 | \1f |
8390 | File: bashref.info, Node: Reporting Bugs, Next: Major Differences From The Bourne Shell, Prev: Installing Bash, Up: Top | |
d166f048 | 8391 | |
37c41ab1 CR |
8392 | Appendix A Reporting Bugs |
8393 | ************************* | |
ccc6cda3 | 8394 | |
37c41ab1 | 8395 | Please report all bugs you find in Bash. But first, you should make |
bb70624e | 8396 | sure that it really is a bug, and that it appears in the latest version |
d3a24ed2 CR |
8397 | of Bash. The latest version of Bash is always available for FTP from |
8398 | `ftp://ftp.gnu.org/pub/bash/'. | |
ccc6cda3 | 8399 | |
bb70624e JA |
8400 | Once you have determined that a bug actually exists, use the |
8401 | `bashbug' command to submit a bug report. If you have a fix, you are | |
8402 | encouraged to mail that as well! Suggestions and `philosophical' bug | |
8403 | reports may be mailed to <bug-bash@gnu.org> or posted to the Usenet | |
8404 | newsgroup `gnu.bash.bug'. | |
ccc6cda3 | 8405 | |
bb70624e JA |
8406 | All bug reports should include: |
8407 | * The version number of Bash. | |
ccc6cda3 | 8408 | |
bb70624e | 8409 | * The hardware and operating system. |
ccc6cda3 | 8410 | |
bb70624e | 8411 | * The compiler used to compile Bash. |
ccc6cda3 | 8412 | |
bb70624e | 8413 | * A description of the bug behaviour. |
ccc6cda3 | 8414 | |
bb70624e JA |
8415 | * A short script or `recipe' which exercises the bug and may be used |
8416 | to reproduce it. | |
ccc6cda3 | 8417 | |
bb70624e JA |
8418 | `bashbug' inserts the first three items automatically into the template |
8419 | it provides for filing a bug report. | |
8420 | ||
8421 | Please send all reports concerning this manual to <chet@po.CWRU.Edu>. | |
ccc6cda3 JA |
8422 | |
8423 | \1f | |
c2a47ea9 | 8424 | File: bashref.info, Node: Major Differences From The Bourne Shell, Next: GNU Free Documentation License, Prev: Reporting Bugs, Up: Top |
ccc6cda3 | 8425 | |
37c41ab1 CR |
8426 | Appendix B Major Differences From The Bourne Shell |
8427 | ************************************************** | |
ccc6cda3 | 8428 | |
37c41ab1 | 8429 | Bash implements essentially the same grammar, parameter and variable |
bb70624e | 8430 | expansion, redirection, and quoting as the Bourne Shell. Bash uses the |
ac18b312 CR |
8431 | POSIX standard as the specification of how these features are to be |
8432 | implemented. There are some differences between the traditional Bourne | |
8433 | shell and Bash; this section quickly details the differences of | |
bb70624e JA |
8434 | significance. A number of these differences are explained in greater |
8435 | depth in previous sections. This section uses the version of `sh' | |
1c72c0cd CR |
8436 | included in SVR4.2 (the last version of the historical Bourne shell) as |
8437 | the baseline reference. | |
ccc6cda3 | 8438 | |
bb70624e | 8439 | * Bash is POSIX-conformant, even where the POSIX specification |
28ef6c31 | 8440 | differs from traditional `sh' behavior (*note Bash POSIX Mode::). |
ccc6cda3 | 8441 | |
bb70624e | 8442 | * Bash has multi-character invocation options (*note Invoking |
28ef6c31 | 8443 | Bash::). |
ccc6cda3 | 8444 | |
28ef6c31 | 8445 | * Bash has command-line editing (*note Command Line Editing::) and |
bb70624e | 8446 | the `bind' builtin. |
ccc6cda3 | 8447 | |
bb70624e | 8448 | * Bash provides a programmable word completion mechanism (*note |
6a8fd0ed CR |
8449 | Programmable Completion::), and builtin commands `complete', |
8450 | `compgen', and `compopt', to manipulate it. | |
ccc6cda3 | 8451 | |
28ef6c31 | 8452 | * Bash has command history (*note Bash History Facilities::) and the |
5e13499c CR |
8453 | `history' and `fc' builtins to manipulate it. The Bash history |
8454 | list maintains timestamp information and uses the value of the | |
8455 | `HISTTIMEFORMAT' variable to display it. | |
ccc6cda3 | 8456 | |
bb70624e | 8457 | * Bash implements `csh'-like history expansion (*note History |
28ef6c31 | 8458 | Interaction::). |
ccc6cda3 | 8459 | |
28ef6c31 | 8460 | * Bash has one-dimensional array variables (*note Arrays::), and the |
bb70624e JA |
8461 | appropriate variable expansions and assignment syntax to use them. |
8462 | Several of the Bash builtins take options to act on arrays. Bash | |
8463 | provides a number of built-in array variables. | |
ccc6cda3 | 8464 | |
bb70624e JA |
8465 | * The `$'...'' quoting syntax, which expands ANSI-C |
8466 | backslash-escaped characters in the text between the single quotes, | |
28ef6c31 | 8467 | is supported (*note ANSI-C Quoting::). |
ccc6cda3 | 8468 | |
bb70624e JA |
8469 | * Bash supports the `$"..."' quoting syntax to do locale-specific |
8470 | translation of the characters between the double quotes. The | |
8471 | `-D', `--dump-strings', and `--dump-po-strings' invocation options | |
8472 | list the translatable strings found in a script (*note Locale | |
28ef6c31 | 8473 | Translation::). |
ccc6cda3 | 8474 | |
bb70624e | 8475 | * Bash implements the `!' keyword to negate the return value of a |
28ef6c31 | 8476 | pipeline (*note Pipelines::). Very useful when an `if' statement |
1c72c0cd CR |
8477 | needs to act only if a test fails. The Bash `-o pipefail' option |
8478 | to `set' will cause a pipeline to return a failure status if any | |
8479 | command fails. | |
ccc6cda3 | 8480 | |
bb70624e | 8481 | * Bash has the `time' reserved word and command timing (*note |
28ef6c31 | 8482 | Pipelines::). The display of the timing statistics may be |
bb70624e | 8483 | controlled with the `TIMEFORMAT' variable. |
ccc6cda3 | 8484 | |
bb70624e JA |
8485 | * Bash implements the `for (( EXPR1 ; EXPR2 ; EXPR3 ))' arithmetic |
8486 | for command, similar to the C language (*note Looping | |
28ef6c31 | 8487 | Constructs::). |
ccc6cda3 | 8488 | |
bb70624e | 8489 | * Bash includes the `select' compound command, which allows the |
28ef6c31 | 8490 | generation of simple menus (*note Conditional Constructs::). |
ccc6cda3 | 8491 | |
bb70624e | 8492 | * Bash includes the `[[' compound command, which makes conditional |
1c72c0cd CR |
8493 | testing part of the shell grammar (*note Conditional |
8494 | Constructs::), including optional regular expression matching. | |
8495 | ||
8496 | * Bash provides optional case-insensitive matching for the `case' and | |
8497 | `[[' constructs. | |
ccc6cda3 | 8498 | |
28ef6c31 JA |
8499 | * Bash includes brace expansion (*note Brace Expansion::) and tilde |
8500 | expansion (*note Tilde Expansion::). | |
ccc6cda3 | 8501 | |
bb70624e | 8502 | * Bash implements command aliases and the `alias' and `unalias' |
28ef6c31 | 8503 | builtins (*note Aliases::). |
ccc6cda3 | 8504 | |
bb70624e | 8505 | * Bash provides shell arithmetic, the `((' compound command (*note |
28ef6c31 JA |
8506 | Conditional Constructs::), and arithmetic expansion (*note Shell |
8507 | Arithmetic::). | |
ccc6cda3 | 8508 | |
bb70624e JA |
8509 | * Variables present in the shell's initial environment are |
8510 | automatically exported to child processes. The Bourne shell does | |
8511 | not normally do this unless the variables are explicitly marked | |
8512 | using the `export' command. | |
ccc6cda3 | 8513 | |
1c72c0cd CR |
8514 | * Bash supports the `+=' assignment operator, which appends to the |
8515 | value of the variable named on the left hand side. | |
8516 | ||
bb70624e JA |
8517 | * Bash includes the POSIX pattern removal `%', `#', `%%' and `##' |
8518 | expansions to remove leading or trailing substrings from variable | |
28ef6c31 | 8519 | values (*note Shell Parameter Expansion::). |
ccc6cda3 | 8520 | |
bb70624e | 8521 | * The expansion `${#xx}', which returns the length of `${xx}', is |
28ef6c31 | 8522 | supported (*note Shell Parameter Expansion::). |
ccc6cda3 | 8523 | |
bb70624e JA |
8524 | * The expansion `${var:'OFFSET`[:'LENGTH`]}', which expands to the |
8525 | substring of `var''s value of length LENGTH, beginning at OFFSET, | |
28ef6c31 | 8526 | is present (*note Shell Parameter Expansion::). |
ccc6cda3 | 8527 | |
bb70624e JA |
8528 | * The expansion `${var/[/]'PATTERN`[/'REPLACEMENT`]}', which matches |
8529 | PATTERN and replaces it with REPLACEMENT in the value of `var', is | |
28ef6c31 | 8530 | available (*note Shell Parameter Expansion::). |
ccc6cda3 | 8531 | |
bb70624e JA |
8532 | * The expansion `${!PREFIX}*' expansion, which expands to the names |
8533 | of all shell variables whose names begin with PREFIX, is available | |
28ef6c31 | 8534 | (*note Shell Parameter Expansion::). |
ccc6cda3 | 8535 | |
bb70624e | 8536 | * Bash has INDIRECT variable expansion using `${!word}' (*note Shell |
28ef6c31 | 8537 | Parameter Expansion::). |
ccc6cda3 | 8538 | |
bb70624e | 8539 | * Bash can expand positional parameters beyond `$9' using `${NUM}'. |
ccc6cda3 | 8540 | |
bb70624e | 8541 | * The POSIX `$()' form of command substitution is implemented (*note |
28ef6c31 | 8542 | Command Substitution::), and preferred to the Bourne shell's ```' |
bb70624e | 8543 | (which is also implemented for backwards compatibility). |
ccc6cda3 | 8544 | |
28ef6c31 | 8545 | * Bash has process substitution (*note Process Substitution::). |
ccc6cda3 | 8546 | |
bb70624e JA |
8547 | * Bash automatically assigns variables that provide information |
8548 | about the current user (`UID', `EUID', and `GROUPS'), the current | |
8549 | host (`HOSTTYPE', `OSTYPE', `MACHTYPE', and `HOSTNAME'), and the | |
8550 | instance of Bash that is running (`BASH', `BASH_VERSION', and | |
8551 | `BASH_VERSINFO'). *Note Bash Variables::, for details. | |
ccc6cda3 | 8552 | |
bb70624e | 8553 | * The `IFS' variable is used to split only the results of expansion, |
28ef6c31 | 8554 | not all words (*note Word Splitting::). This closes a |
bb70624e | 8555 | longstanding shell security hole. |
ccc6cda3 | 8556 | |
ac18b312 CR |
8557 | * Bash implements the full set of POSIX filename expansion operators, |
8558 | including CHARACTER CLASSES, EQUIVALENCE CLASSES, and COLLATING | |
8559 | SYMBOLS (*note Filename Expansion::). | |
ccc6cda3 | 8560 | |
bb70624e | 8561 | * Bash implements extended pattern matching features when the |
28ef6c31 | 8562 | `extglob' shell option is enabled (*note Pattern Matching::). |
ccc6cda3 | 8563 | |
bb70624e JA |
8564 | * It is possible to have a variable and a function with the same |
8565 | name; `sh' does not separate the two name spaces. | |
ccc6cda3 | 8566 | |
bb70624e JA |
8567 | * Bash functions are permitted to have local variables using the |
8568 | `local' builtin, and thus useful recursive functions may be written | |
28ef6c31 | 8569 | (*note Bash Builtins::). |
ccc6cda3 | 8570 | |
bb70624e | 8571 | * Variable assignments preceding commands affect only that command, |
28ef6c31 | 8572 | even builtins and functions (*note Environment::). In `sh', all |
bb70624e JA |
8573 | variable assignments preceding commands are global unless the |
8574 | command is executed from the file system. | |
ccc6cda3 | 8575 | |
bb70624e | 8576 | * Bash performs filename expansion on filenames specified as operands |
28ef6c31 | 8577 | to input and output redirection operators (*note Redirections::). |
ccc6cda3 | 8578 | |
bb70624e JA |
8579 | * Bash contains the `<>' redirection operator, allowing a file to be |
8580 | opened for both reading and writing, and the `&>' redirection | |
8581 | operator, for directing standard output and standard error to the | |
28ef6c31 | 8582 | same file (*note Redirections::). |
d166f048 | 8583 | |
1c72c0cd CR |
8584 | * Bash includes the `<<<' redirection operator, allowing a string to |
8585 | be used as the standard input to a command. | |
8586 | ||
8587 | * Bash implements the `[n]<&WORD' and `[n]>&WORD' redirection | |
8588 | operators, which move one file descriptor to another. | |
8589 | ||
bb70624e | 8590 | * Bash treats a number of filenames specially when they are used in |
28ef6c31 | 8591 | redirection operators (*note Redirections::). |
ccc6cda3 | 8592 | |
bb70624e | 8593 | * Bash can open network connections to arbitrary machines and |
28ef6c31 | 8594 | services with the redirection operators (*note Redirections::). |
ccc6cda3 | 8595 | |
bb70624e | 8596 | * The `noclobber' option is available to avoid overwriting existing |
28ef6c31 JA |
8597 | files with output redirection (*note The Set Builtin::). The `>|' |
8598 | redirection operator may be used to override `noclobber'. | |
ccc6cda3 | 8599 | |
28ef6c31 JA |
8600 | * The Bash `cd' and `pwd' builtins (*note Bourne Shell Builtins::) |
8601 | each take `-L' and `-P' options to switch between logical and | |
bb70624e | 8602 | physical modes. |
b72432fd | 8603 | |
bb70624e JA |
8604 | * Bash allows a function to override a builtin with the same name, |
8605 | and provides access to that builtin's functionality within the | |
8606 | function via the `builtin' and `command' builtins (*note Bash | |
28ef6c31 | 8607 | Builtins::). |
ccc6cda3 | 8608 | |
bb70624e | 8609 | * The `command' builtin allows selective disabling of functions when |
28ef6c31 | 8610 | command lookup is performed (*note Bash Builtins::). |
ccc6cda3 | 8611 | |
bb70624e | 8612 | * Individual builtins may be enabled or disabled using the `enable' |
28ef6c31 | 8613 | builtin (*note Bash Builtins::). |
cce855bc | 8614 | |
bb70624e JA |
8615 | * The Bash `exec' builtin takes additional options that allow users |
8616 | to control the contents of the environment passed to the executed | |
8617 | command, and what the zeroth argument to the command is to be | |
28ef6c31 | 8618 | (*note Bourne Shell Builtins::). |
cce855bc | 8619 | |
bb70624e | 8620 | * Shell functions may be exported to children via the environment |
28ef6c31 | 8621 | using `export -f' (*note Shell Functions::). |
cce855bc | 8622 | |
bb70624e JA |
8623 | * The Bash `export', `readonly', and `declare' builtins can take a |
8624 | `-f' option to act on shell functions, a `-p' option to display | |
8625 | variables with various attributes set in a format that can be used | |
8626 | as shell input, a `-n' option to remove various variable | |
8627 | attributes, and `name=value' arguments to set variable attributes | |
8628 | and values simultaneously. | |
ccc6cda3 | 8629 | |
bb70624e JA |
8630 | * The Bash `hash' builtin allows a name to be associated with an |
8631 | arbitrary filename, even when that filename cannot be found by | |
8632 | searching the `$PATH', using `hash -p' (*note Bourne Shell | |
28ef6c31 | 8633 | Builtins::). |
ccc6cda3 | 8634 | |
bb70624e | 8635 | * Bash includes a `help' builtin for quick reference to shell |
28ef6c31 | 8636 | facilities (*note Bash Builtins::). |
ccc6cda3 | 8637 | |
bb70624e | 8638 | * The `printf' builtin is available to display formatted output |
28ef6c31 | 8639 | (*note Bash Builtins::). |
ccc6cda3 | 8640 | |
28ef6c31 | 8641 | * The Bash `read' builtin (*note Bash Builtins::) will read a line |
bb70624e JA |
8642 | ending in `\' with the `-r' option, and will use the `REPLY' |
8643 | variable as a default if no non-option arguments are supplied. | |
8644 | The Bash `read' builtin also accepts a prompt string with the `-p' | |
8645 | option and will use Readline to obtain the line when given the | |
8646 | `-e' option. The `read' builtin also has additional options to | |
8647 | control input: the `-s' option will turn off echoing of input | |
8648 | characters as they are read, the `-t' option will allow `read' to | |
8649 | time out if input does not arrive within a specified number of | |
8650 | seconds, the `-n' option will allow reading only a specified | |
8651 | number of characters rather than a full line, and the `-d' option | |
8652 | will read until a particular character rather than newline. | |
ccc6cda3 | 8653 | |
bb70624e JA |
8654 | * The `return' builtin may be used to abort execution of scripts |
8655 | executed with the `.' or `source' builtins (*note Bourne Shell | |
28ef6c31 | 8656 | Builtins::). |
d166f048 | 8657 | |
bb70624e | 8658 | * Bash includes the `shopt' builtin, for finer control of shell |
d3ad40de CR |
8659 | optional capabilities (*note The Shopt Builtin::), and allows |
8660 | these options to be set and unset at shell invocation (*note | |
8661 | Invoking Bash::). | |
d166f048 | 8662 | |
bb70624e | 8663 | * Bash has much more optional behavior controllable with the `set' |
28ef6c31 | 8664 | builtin (*note The Set Builtin::). |
cce855bc | 8665 | |
5e13499c CR |
8666 | * The `-x' (`xtrace') option displays commands other than simple |
8667 | commands when performing an execution trace (*note The Set | |
8668 | Builtin::). | |
8669 | ||
28ef6c31 | 8670 | * The `test' builtin (*note Bourne Shell Builtins::) is slightly |
bb70624e JA |
8671 | different, as it implements the POSIX algorithm, which specifies |
8672 | the behavior based on the number of arguments. | |
ccc6cda3 | 8673 | |
5e13499c CR |
8674 | * Bash includes the `caller' builtin, which displays the context of |
8675 | any active subroutine call (a shell function or a script executed | |
8676 | with the `.' or `source' builtins). This supports the bash | |
8677 | debugger. | |
8678 | ||
28ef6c31 | 8679 | * The `trap' builtin (*note Bourne Shell Builtins::) allows a |
bb70624e | 8680 | `DEBUG' pseudo-signal specification, similar to `EXIT'. Commands |
d3a24ed2 CR |
8681 | specified with a `DEBUG' trap are executed before every simple |
8682 | command, `for' command, `case' command, `select' command, every | |
8683 | arithmetic `for' command, and before the first command executes in | |
8684 | a shell function. The `DEBUG' trap is not inherited by shell | |
8685 | functions unless the function has been given the `trace' attribute | |
8686 | or the `functrace' option has been enabled using the `shopt' | |
8687 | builtin. The `extdebug' shell option has additional effects on the | |
8688 | `DEBUG' trap. | |
d166f048 | 8689 | |
f73dda09 JA |
8690 | The `trap' builtin (*note Bourne Shell Builtins::) allows an `ERR' |
8691 | pseudo-signal specification, similar to `EXIT' and `DEBUG'. | |
8692 | Commands specified with an `ERR' trap are executed after a simple | |
8693 | command fails, with a few exceptions. The `ERR' trap is not | |
d3a24ed2 CR |
8694 | inherited by shell functions unless the `-o errtrace' option to |
8695 | the `set' builtin is enabled. | |
8696 | ||
8697 | The `trap' builtin (*note Bourne Shell Builtins::) allows a | |
8698 | `RETURN' pseudo-signal specification, similar to `EXIT' and | |
8699 | `DEBUG'. Commands specified with an `RETURN' trap are executed | |
8700 | before execution resumes after a shell function or a shell script | |
8701 | executed with `.' or `source' returns. The `RETURN' trap is not | |
8fed3589 CR |
8702 | inherited by shell functions unless the function has been given |
8703 | the `trace' attribute or the `functrace' option has been enabled | |
8704 | using the `shopt' builtin. | |
f73dda09 | 8705 | |
bb70624e | 8706 | * The Bash `type' builtin is more extensive and gives more |
28ef6c31 | 8707 | information about the names it finds (*note Bash Builtins::). |
cce855bc | 8708 | |
bb70624e JA |
8709 | * The Bash `umask' builtin permits a `-p' option to cause the output |
8710 | to be displayed in the form of a `umask' command that may be | |
28ef6c31 | 8711 | reused as input (*note Bourne Shell Builtins::). |
d166f048 | 8712 | |
bb70624e JA |
8713 | * Bash implements a `csh'-like directory stack, and provides the |
8714 | `pushd', `popd', and `dirs' builtins to manipulate it (*note The | |
28ef6c31 | 8715 | Directory Stack::). Bash also makes the directory stack visible |
bb70624e | 8716 | as the value of the `DIRSTACK' shell variable. |
d166f048 | 8717 | |
bb70624e | 8718 | * Bash interprets special backslash-escaped characters in the prompt |
28ef6c31 | 8719 | strings when interactive (*note Printing a Prompt::). |
d166f048 | 8720 | |
bb70624e | 8721 | * The Bash restricted mode is more useful (*note The Restricted |
28ef6c31 | 8722 | Shell::); the SVR4.2 shell restricted mode is too limited. |
ccc6cda3 | 8723 | |
bb70624e | 8724 | * The `disown' builtin can remove a job from the internal shell job |
28ef6c31 | 8725 | table (*note Job Control Builtins::) or suppress the sending of |
bb70624e | 8726 | `SIGHUP' to a job when the shell exits as the result of a `SIGHUP'. |
ccc6cda3 | 8727 | |
1c72c0cd CR |
8728 | * Bash includes a number of features to support a separate debugger |
8729 | for shell scripts. | |
8730 | ||
bb70624e JA |
8731 | * The SVR4.2 shell has two privilege-related builtins (`mldmode' and |
8732 | `priv') not present in Bash. | |
ccc6cda3 | 8733 | |
bb70624e | 8734 | * Bash does not have the `stop' or `newgrp' builtins. |
d166f048 | 8735 | |
bb70624e JA |
8736 | * Bash does not use the `SHACCT' variable or perform shell |
8737 | accounting. | |
d166f048 | 8738 | |
bb70624e | 8739 | * The SVR4.2 `sh' uses a `TIMEOUT' variable like Bash uses `TMOUT'. |
ccc6cda3 | 8740 | |
28ef6c31 | 8741 | |
6a8fd0ed | 8742 | More features unique to Bash may be found in *note Bash Features::. |
ccc6cda3 | 8743 | |
37c41ab1 CR |
8744 | B.1 Implementation Differences From The SVR4.2 Shell |
8745 | ==================================================== | |
ccc6cda3 | 8746 | |
37c41ab1 CR |
8747 | Since Bash is a completely new implementation, it does not suffer from |
8748 | many of the limitations of the SVR4.2 shell. For instance: | |
ccc6cda3 | 8749 | |
bb70624e JA |
8750 | * Bash does not fork a subshell when redirecting into or out of a |
8751 | shell control structure such as an `if' or `while' statement. | |
ccc6cda3 | 8752 | |
bb70624e JA |
8753 | * Bash does not allow unbalanced quotes. The SVR4.2 shell will |
8754 | silently insert a needed closing quote at `EOF' under certain | |
8755 | circumstances. This can be the cause of some hard-to-find errors. | |
ccc6cda3 | 8756 | |
bb70624e JA |
8757 | * The SVR4.2 shell uses a baroque memory management scheme based on |
8758 | trapping `SIGSEGV'. If the shell is started from a process with | |
8759 | `SIGSEGV' blocked (e.g., by using the `system()' C library | |
8760 | function call), it misbehaves badly. | |
ccc6cda3 | 8761 | |
bb70624e JA |
8762 | * In a questionable attempt at security, the SVR4.2 shell, when |
8763 | invoked without the `-p' option, will alter its real and effective | |
8764 | UID and GID if they are less than some magic threshold value, | |
8765 | commonly 100. This can lead to unexpected results. | |
ccc6cda3 | 8766 | |
bb70624e JA |
8767 | * The SVR4.2 shell does not allow users to trap `SIGSEGV', |
8768 | `SIGALRM', or `SIGCHLD'. | |
ccc6cda3 | 8769 | |
bb70624e JA |
8770 | * The SVR4.2 shell does not allow the `IFS', `MAILCHECK', `PATH', |
8771 | `PS1', or `PS2' variables to be unset. | |
ccc6cda3 | 8772 | |
bb70624e | 8773 | * The SVR4.2 shell treats `^' as the undocumented equivalent of `|'. |
ccc6cda3 | 8774 | |
bb70624e JA |
8775 | * Bash allows multiple option arguments when it is invoked (`-x -v'); |
8776 | the SVR4.2 shell allows only one option argument (`-xv'). In | |
8777 | fact, some versions of the shell dump core if the second argument | |
8778 | begins with a `-'. | |
ccc6cda3 | 8779 | |
bb70624e | 8780 | * The SVR4.2 shell exits a script if any builtin fails; Bash exits a |
ac18b312 CR |
8781 | script only if one of the POSIX special builtins fails, and only |
8782 | for certain failures, as enumerated in the POSIX standard. | |
ccc6cda3 | 8783 | |
bb70624e JA |
8784 | * The SVR4.2 shell behaves differently when invoked as `jsh' (it |
8785 | turns on job control). | |
ccc6cda3 JA |
8786 | |
8787 | \1f | |
c2a47ea9 | 8788 | File: bashref.info, Node: GNU Free Documentation License, Next: Indexes, Prev: Major Differences From The Bourne Shell, Up: Top |
d3a24ed2 | 8789 | |
c2a47ea9 CR |
8790 | Appendix C GNU Free Documentation License |
8791 | ***************************************** | |
d3a24ed2 CR |
8792 | |
8793 | Version 1.2, November 2002 | |
37c41ab1 | 8794 | |
d3a24ed2 | 8795 | Copyright (C) 2000,2001,2002 Free Software Foundation, Inc. |
c2a47ea9 | 8796 | 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA |
37c41ab1 | 8797 | |
d3a24ed2 CR |
8798 | Everyone is permitted to copy and distribute verbatim copies |
8799 | of this license document, but changing it is not allowed. | |
8800 | ||
8801 | 0. PREAMBLE | |
8802 | ||
8803 | The purpose of this License is to make a manual, textbook, or other | |
8804 | functional and useful document "free" in the sense of freedom: to | |
8805 | assure everyone the effective freedom to copy and redistribute it, | |
8806 | with or without modifying it, either commercially or | |
8807 | noncommercially. Secondarily, this License preserves for the | |
8808 | author and publisher a way to get credit for their work, while not | |
8809 | being considered responsible for modifications made by others. | |
8810 | ||
8811 | This License is a kind of "copyleft", which means that derivative | |
8812 | works of the document must themselves be free in the same sense. | |
8813 | It complements the GNU General Public License, which is a copyleft | |
8814 | license designed for free software. | |
8815 | ||
8816 | We have designed this License in order to use it for manuals for | |
8817 | free software, because free software needs free documentation: a | |
8818 | free program should come with manuals providing the same freedoms | |
8819 | that the software does. But this License is not limited to | |
8820 | software manuals; it can be used for any textual work, regardless | |
8821 | of subject matter or whether it is published as a printed book. | |
8822 | We recommend this License principally for works whose purpose is | |
8823 | instruction or reference. | |
8824 | ||
8825 | 1. APPLICABILITY AND DEFINITIONS | |
8826 | ||
8827 | This License applies to any manual or other work, in any medium, | |
8828 | that contains a notice placed by the copyright holder saying it | |
8829 | can be distributed under the terms of this License. Such a notice | |
8830 | grants a world-wide, royalty-free license, unlimited in duration, | |
8831 | to use that work under the conditions stated herein. The | |
8832 | "Document", below, refers to any such manual or work. Any member | |
8833 | of the public is a licensee, and is addressed as "you". You | |
8834 | accept the license if you copy, modify or distribute the work in a | |
8835 | way requiring permission under copyright law. | |
8836 | ||
8837 | A "Modified Version" of the Document means any work containing the | |
8838 | Document or a portion of it, either copied verbatim, or with | |
8839 | modifications and/or translated into another language. | |
8840 | ||
8841 | A "Secondary Section" is a named appendix or a front-matter section | |
8842 | of the Document that deals exclusively with the relationship of the | |
8843 | publishers or authors of the Document to the Document's overall | |
8844 | subject (or to related matters) and contains nothing that could | |
8845 | fall directly within that overall subject. (Thus, if the Document | |
8846 | is in part a textbook of mathematics, a Secondary Section may not | |
8847 | explain any mathematics.) The relationship could be a matter of | |
8848 | historical connection with the subject or with related matters, or | |
8849 | of legal, commercial, philosophical, ethical or political position | |
8850 | regarding them. | |
8851 | ||
8852 | The "Invariant Sections" are certain Secondary Sections whose | |
8853 | titles are designated, as being those of Invariant Sections, in | |
8854 | the notice that says that the Document is released under this | |
8855 | License. If a section does not fit the above definition of | |
8856 | Secondary then it is not allowed to be designated as Invariant. | |
8857 | The Document may contain zero Invariant Sections. If the Document | |
8858 | does not identify any Invariant Sections then there are none. | |
8859 | ||
8860 | The "Cover Texts" are certain short passages of text that are | |
8861 | listed, as Front-Cover Texts or Back-Cover Texts, in the notice | |
8862 | that says that the Document is released under this License. A | |
8863 | Front-Cover Text may be at most 5 words, and a Back-Cover Text may | |
8864 | be at most 25 words. | |
8865 | ||
8866 | A "Transparent" copy of the Document means a machine-readable copy, | |
8867 | represented in a format whose specification is available to the | |
8868 | general public, that is suitable for revising the document | |
8869 | straightforwardly with generic text editors or (for images | |
8870 | composed of pixels) generic paint programs or (for drawings) some | |
8871 | widely available drawing editor, and that is suitable for input to | |
8872 | text formatters or for automatic translation to a variety of | |
8873 | formats suitable for input to text formatters. A copy made in an | |
8874 | otherwise Transparent file format whose markup, or absence of | |
8875 | markup, has been arranged to thwart or discourage subsequent | |
8876 | modification by readers is not Transparent. An image format is | |
8877 | not Transparent if used for any substantial amount of text. A | |
8878 | copy that is not "Transparent" is called "Opaque". | |
8879 | ||
8880 | Examples of suitable formats for Transparent copies include plain | |
8881 | ASCII without markup, Texinfo input format, LaTeX input format, | |
8882 | SGML or XML using a publicly available DTD, and | |
8883 | standard-conforming simple HTML, PostScript or PDF designed for | |
8884 | human modification. Examples of transparent image formats include | |
8885 | PNG, XCF and JPG. Opaque formats include proprietary formats that | |
8886 | can be read and edited only by proprietary word processors, SGML or | |
8887 | XML for which the DTD and/or processing tools are not generally | |
8888 | available, and the machine-generated HTML, PostScript or PDF | |
8889 | produced by some word processors for output purposes only. | |
8890 | ||
8891 | The "Title Page" means, for a printed book, the title page itself, | |
8892 | plus such following pages as are needed to hold, legibly, the | |
8893 | material this License requires to appear in the title page. For | |
8894 | works in formats which do not have any title page as such, "Title | |
8895 | Page" means the text near the most prominent appearance of the | |
8896 | work's title, preceding the beginning of the body of the text. | |
8897 | ||
8898 | A section "Entitled XYZ" means a named subunit of the Document | |
8899 | whose title either is precisely XYZ or contains XYZ in parentheses | |
8900 | following text that translates XYZ in another language. (Here XYZ | |
8901 | stands for a specific section name mentioned below, such as | |
8902 | "Acknowledgements", "Dedications", "Endorsements", or "History".) | |
8903 | To "Preserve the Title" of such a section when you modify the | |
8904 | Document means that it remains a section "Entitled XYZ" according | |
8905 | to this definition. | |
8906 | ||
8907 | The Document may include Warranty Disclaimers next to the notice | |
8908 | which states that this License applies to the Document. These | |
8909 | Warranty Disclaimers are considered to be included by reference in | |
8910 | this License, but only as regards disclaiming warranties: any other | |
8911 | implication that these Warranty Disclaimers may have is void and | |
8912 | has no effect on the meaning of this License. | |
8913 | ||
8914 | 2. VERBATIM COPYING | |
8915 | ||
8916 | You may copy and distribute the Document in any medium, either | |
8917 | commercially or noncommercially, provided that this License, the | |
8918 | copyright notices, and the license notice saying this License | |
8919 | applies to the Document are reproduced in all copies, and that you | |
8920 | add no other conditions whatsoever to those of this License. You | |
8921 | may not use technical measures to obstruct or control the reading | |
8922 | or further copying of the copies you make or distribute. However, | |
8923 | you may accept compensation in exchange for copies. If you | |
8924 | distribute a large enough number of copies you must also follow | |
8925 | the conditions in section 3. | |
8926 | ||
8927 | You may also lend copies, under the same conditions stated above, | |
8928 | and you may publicly display copies. | |
8929 | ||
8930 | 3. COPYING IN QUANTITY | |
8931 | ||
8932 | If you publish printed copies (or copies in media that commonly | |
8933 | have printed covers) of the Document, numbering more than 100, and | |
8934 | the Document's license notice requires Cover Texts, you must | |
8935 | enclose the copies in covers that carry, clearly and legibly, all | |
8936 | these Cover Texts: Front-Cover Texts on the front cover, and | |
8937 | Back-Cover Texts on the back cover. Both covers must also clearly | |
8938 | and legibly identify you as the publisher of these copies. The | |
8939 | front cover must present the full title with all words of the | |
8940 | title equally prominent and visible. You may add other material | |
8941 | on the covers in addition. Copying with changes limited to the | |
8942 | covers, as long as they preserve the title of the Document and | |
8943 | satisfy these conditions, can be treated as verbatim copying in | |
8944 | other respects. | |
8945 | ||
8946 | If the required texts for either cover are too voluminous to fit | |
8947 | legibly, you should put the first ones listed (as many as fit | |
8948 | reasonably) on the actual cover, and continue the rest onto | |
8949 | adjacent pages. | |
8950 | ||
8951 | If you publish or distribute Opaque copies of the Document | |
8952 | numbering more than 100, you must either include a | |
8953 | machine-readable Transparent copy along with each Opaque copy, or | |
8954 | state in or with each Opaque copy a computer-network location from | |
8955 | which the general network-using public has access to download | |
8956 | using public-standard network protocols a complete Transparent | |
8957 | copy of the Document, free of added material. If you use the | |
8958 | latter option, you must take reasonably prudent steps, when you | |
8959 | begin distribution of Opaque copies in quantity, to ensure that | |
8960 | this Transparent copy will remain thus accessible at the stated | |
8961 | location until at least one year after the last time you | |
8962 | distribute an Opaque copy (directly or through your agents or | |
8963 | retailers) of that edition to the public. | |
8964 | ||
8965 | It is requested, but not required, that you contact the authors of | |
8966 | the Document well before redistributing any large number of | |
8967 | copies, to give them a chance to provide you with an updated | |
8968 | version of the Document. | |
8969 | ||
8970 | 4. MODIFICATIONS | |
8971 | ||
8972 | You may copy and distribute a Modified Version of the Document | |
8973 | under the conditions of sections 2 and 3 above, provided that you | |
8974 | release the Modified Version under precisely this License, with | |
8975 | the Modified Version filling the role of the Document, thus | |
8976 | licensing distribution and modification of the Modified Version to | |
8977 | whoever possesses a copy of it. In addition, you must do these | |
8978 | things in the Modified Version: | |
8979 | ||
8980 | A. Use in the Title Page (and on the covers, if any) a title | |
8981 | distinct from that of the Document, and from those of | |
8982 | previous versions (which should, if there were any, be listed | |
8983 | in the History section of the Document). You may use the | |
8984 | same title as a previous version if the original publisher of | |
8985 | that version gives permission. | |
8986 | ||
8987 | B. List on the Title Page, as authors, one or more persons or | |
8988 | entities responsible for authorship of the modifications in | |
8989 | the Modified Version, together with at least five of the | |
8990 | principal authors of the Document (all of its principal | |
8991 | authors, if it has fewer than five), unless they release you | |
8992 | from this requirement. | |
8993 | ||
8994 | C. State on the Title page the name of the publisher of the | |
8995 | Modified Version, as the publisher. | |
8996 | ||
8997 | D. Preserve all the copyright notices of the Document. | |
8998 | ||
8999 | E. Add an appropriate copyright notice for your modifications | |
9000 | adjacent to the other copyright notices. | |
9001 | ||
9002 | F. Include, immediately after the copyright notices, a license | |
9003 | notice giving the public permission to use the Modified | |
9004 | Version under the terms of this License, in the form shown in | |
9005 | the Addendum below. | |
9006 | ||
9007 | G. Preserve in that license notice the full lists of Invariant | |
9008 | Sections and required Cover Texts given in the Document's | |
9009 | license notice. | |
9010 | ||
9011 | H. Include an unaltered copy of this License. | |
9012 | ||
9013 | I. Preserve the section Entitled "History", Preserve its Title, | |
9014 | and add to it an item stating at least the title, year, new | |
9015 | authors, and publisher of the Modified Version as given on | |
9016 | the Title Page. If there is no section Entitled "History" in | |
9017 | the Document, create one stating the title, year, authors, | |
9018 | and publisher of the Document as given on its Title Page, | |
9019 | then add an item describing the Modified Version as stated in | |
9020 | the previous sentence. | |
9021 | ||
9022 | J. Preserve the network location, if any, given in the Document | |
9023 | for public access to a Transparent copy of the Document, and | |
9024 | likewise the network locations given in the Document for | |
9025 | previous versions it was based on. These may be placed in | |
9026 | the "History" section. You may omit a network location for a | |
9027 | work that was published at least four years before the | |
9028 | Document itself, or if the original publisher of the version | |
9029 | it refers to gives permission. | |
9030 | ||
9031 | K. For any section Entitled "Acknowledgements" or "Dedications", | |
9032 | Preserve the Title of the section, and preserve in the | |
9033 | section all the substance and tone of each of the contributor | |
9034 | acknowledgements and/or dedications given therein. | |
9035 | ||
9036 | L. Preserve all the Invariant Sections of the Document, | |
9037 | unaltered in their text and in their titles. Section numbers | |
9038 | or the equivalent are not considered part of the section | |
9039 | titles. | |
9040 | ||
9041 | M. Delete any section Entitled "Endorsements". Such a section | |
9042 | may not be included in the Modified Version. | |
9043 | ||
9044 | N. Do not retitle any existing section to be Entitled | |
9045 | "Endorsements" or to conflict in title with any Invariant | |
9046 | Section. | |
9047 | ||
9048 | O. Preserve any Warranty Disclaimers. | |
9049 | ||
9050 | If the Modified Version includes new front-matter sections or | |
9051 | appendices that qualify as Secondary Sections and contain no | |
9052 | material copied from the Document, you may at your option | |
9053 | designate some or all of these sections as invariant. To do this, | |
9054 | add their titles to the list of Invariant Sections in the Modified | |
9055 | Version's license notice. These titles must be distinct from any | |
9056 | other section titles. | |
9057 | ||
9058 | You may add a section Entitled "Endorsements", provided it contains | |
9059 | nothing but endorsements of your Modified Version by various | |
9060 | parties--for example, statements of peer review or that the text | |
9061 | has been approved by an organization as the authoritative | |
9062 | definition of a standard. | |
9063 | ||
9064 | You may add a passage of up to five words as a Front-Cover Text, | |
9065 | and a passage of up to 25 words as a Back-Cover Text, to the end | |
9066 | of the list of Cover Texts in the Modified Version. Only one | |
9067 | passage of Front-Cover Text and one of Back-Cover Text may be | |
9068 | added by (or through arrangements made by) any one entity. If the | |
9069 | Document already includes a cover text for the same cover, | |
9070 | previously added by you or by arrangement made by the same entity | |
9071 | you are acting on behalf of, you may not add another; but you may | |
9072 | replace the old one, on explicit permission from the previous | |
9073 | publisher that added the old one. | |
9074 | ||
9075 | The author(s) and publisher(s) of the Document do not by this | |
9076 | License give permission to use their names for publicity for or to | |
9077 | assert or imply endorsement of any Modified Version. | |
9078 | ||
9079 | 5. COMBINING DOCUMENTS | |
9080 | ||
9081 | You may combine the Document with other documents released under | |
9082 | this License, under the terms defined in section 4 above for | |
9083 | modified versions, provided that you include in the combination | |
9084 | all of the Invariant Sections of all of the original documents, | |
9085 | unmodified, and list them all as Invariant Sections of your | |
9086 | combined work in its license notice, and that you preserve all | |
9087 | their Warranty Disclaimers. | |
9088 | ||
9089 | The combined work need only contain one copy of this License, and | |
9090 | multiple identical Invariant Sections may be replaced with a single | |
9091 | copy. If there are multiple Invariant Sections with the same name | |
9092 | but different contents, make the title of each such section unique | |
9093 | by adding at the end of it, in parentheses, the name of the | |
9094 | original author or publisher of that section if known, or else a | |
9095 | unique number. Make the same adjustment to the section titles in | |
9096 | the list of Invariant Sections in the license notice of the | |
9097 | combined work. | |
9098 | ||
9099 | In the combination, you must combine any sections Entitled | |
9100 | "History" in the various original documents, forming one section | |
9101 | Entitled "History"; likewise combine any sections Entitled | |
9102 | "Acknowledgements", and any sections Entitled "Dedications". You | |
9103 | must delete all sections Entitled "Endorsements." | |
9104 | ||
9105 | 6. COLLECTIONS OF DOCUMENTS | |
9106 | ||
9107 | You may make a collection consisting of the Document and other | |
9108 | documents released under this License, and replace the individual | |
9109 | copies of this License in the various documents with a single copy | |
9110 | that is included in the collection, provided that you follow the | |
9111 | rules of this License for verbatim copying of each of the | |
9112 | documents in all other respects. | |
9113 | ||
9114 | You may extract a single document from such a collection, and | |
9115 | distribute it individually under this License, provided you insert | |
9116 | a copy of this License into the extracted document, and follow | |
9117 | this License in all other respects regarding verbatim copying of | |
9118 | that document. | |
9119 | ||
9120 | 7. AGGREGATION WITH INDEPENDENT WORKS | |
9121 | ||
9122 | A compilation of the Document or its derivatives with other | |
9123 | separate and independent documents or works, in or on a volume of | |
9124 | a storage or distribution medium, is called an "aggregate" if the | |
9125 | copyright resulting from the compilation is not used to limit the | |
9126 | legal rights of the compilation's users beyond what the individual | |
c2a47ea9 | 9127 | works permit. When the Document is included in an aggregate, this |
d3a24ed2 CR |
9128 | License does not apply to the other works in the aggregate which |
9129 | are not themselves derivative works of the Document. | |
9130 | ||
9131 | If the Cover Text requirement of section 3 is applicable to these | |
9132 | copies of the Document, then if the Document is less than one half | |
9133 | of the entire aggregate, the Document's Cover Texts may be placed | |
9134 | on covers that bracket the Document within the aggregate, or the | |
9135 | electronic equivalent of covers if the Document is in electronic | |
9136 | form. Otherwise they must appear on printed covers that bracket | |
9137 | the whole aggregate. | |
9138 | ||
9139 | 8. TRANSLATION | |
9140 | ||
9141 | Translation is considered a kind of modification, so you may | |
9142 | distribute translations of the Document under the terms of section | |
9143 | 4. Replacing Invariant Sections with translations requires special | |
9144 | permission from their copyright holders, but you may include | |
9145 | translations of some or all Invariant Sections in addition to the | |
9146 | original versions of these Invariant Sections. You may include a | |
9147 | translation of this License, and all the license notices in the | |
9148 | Document, and any Warranty Disclaimers, provided that you also | |
9149 | include the original English version of this License and the | |
9150 | original versions of those notices and disclaimers. In case of a | |
9151 | disagreement between the translation and the original version of | |
9152 | this License or a notice or disclaimer, the original version will | |
9153 | prevail. | |
9154 | ||
9155 | If a section in the Document is Entitled "Acknowledgements", | |
9156 | "Dedications", or "History", the requirement (section 4) to | |
9157 | Preserve its Title (section 1) will typically require changing the | |
9158 | actual title. | |
9159 | ||
9160 | 9. TERMINATION | |
9161 | ||
9162 | You may not copy, modify, sublicense, or distribute the Document | |
9163 | except as expressly provided for under this License. Any other | |
9164 | attempt to copy, modify, sublicense or distribute the Document is | |
9165 | void, and will automatically terminate your rights under this | |
9166 | License. However, parties who have received copies, or rights, | |
9167 | from you under this License will not have their licenses | |
9168 | terminated so long as such parties remain in full compliance. | |
9169 | ||
9170 | 10. FUTURE REVISIONS OF THIS LICENSE | |
9171 | ||
9172 | The Free Software Foundation may publish new, revised versions of | |
9173 | the GNU Free Documentation License from time to time. Such new | |
9174 | versions will be similar in spirit to the present version, but may | |
9175 | differ in detail to address new problems or concerns. See | |
9176 | `http://www.gnu.org/copyleft/'. | |
9177 | ||
9178 | Each version of the License is given a distinguishing version | |
9179 | number. If the Document specifies that a particular numbered | |
9180 | version of this License "or any later version" applies to it, you | |
9181 | have the option of following the terms and conditions either of | |
9182 | that specified version or of any later version that has been | |
9183 | published (not as a draft) by the Free Software Foundation. If | |
9184 | the Document does not specify a version number of this License, | |
9185 | you may choose any version ever published (not as a draft) by the | |
9186 | Free Software Foundation. | |
9187 | ||
c2a47ea9 CR |
9188 | ADDENDUM: How to use this License for your documents |
9189 | ==================================================== | |
d3a24ed2 | 9190 | |
37c41ab1 | 9191 | To use this License in a document you have written, include a copy of |
d3a24ed2 CR |
9192 | the License in the document and put the following copyright and license |
9193 | notices just after the title page: | |
9194 | ||
9195 | Copyright (C) YEAR YOUR NAME. | |
9196 | Permission is granted to copy, distribute and/or modify this document | |
9197 | under the terms of the GNU Free Documentation License, Version 1.2 | |
9198 | or any later version published by the Free Software Foundation; | |
c2a47ea9 CR |
9199 | with no Invariant Sections, no Front-Cover Texts, and no Back-Cover |
9200 | Texts. A copy of the license is included in the section entitled ``GNU | |
d3a24ed2 CR |
9201 | Free Documentation License''. |
9202 | ||
9203 | If you have Invariant Sections, Front-Cover Texts and Back-Cover | |
9204 | Texts, replace the "with...Texts." line with this: | |
9205 | ||
9206 | with the Invariant Sections being LIST THEIR TITLES, with | |
9207 | the Front-Cover Texts being LIST, and with the Back-Cover Texts | |
9208 | being LIST. | |
9209 | ||
9210 | If you have Invariant Sections without Cover Texts, or some other | |
9211 | combination of the three, merge those two alternatives to suit the | |
9212 | situation. | |
9213 | ||
9214 | If your document contains nontrivial examples of program code, we | |
9215 | recommend releasing these examples in parallel under your choice of | |
9216 | free software license, such as the GNU General Public License, to | |
9217 | permit their use in free software. | |
9218 | ||
9219 | \1f | |
c2a47ea9 | 9220 | File: bashref.info, Node: Indexes, Prev: GNU Free Documentation License, Up: Top |
d3ad40de CR |
9221 | |
9222 | Appendix D Indexes | |
9223 | ****************** | |
9224 | ||
9225 | * Menu: | |
9226 | ||
9227 | * Builtin Index:: Index of Bash builtin commands. | |
9228 | * Reserved Word Index:: Index of Bash reserved words. | |
9229 | * Variable Index:: Quick reference helps you find the | |
9230 | variable you want. | |
9231 | * Function Index:: Index of bindable Readline functions. | |
9232 | * Concept Index:: General index for concepts described in | |
9233 | this manual. | |
9234 | ||
9235 | \1f | |
9236 | File: bashref.info, Node: Builtin Index, Next: Reserved Word Index, Up: Indexes | |
5cfe250d | 9237 | |
d3ad40de CR |
9238 | D.1 Index of Shell Builtin Commands |
9239 | =================================== | |
ccc6cda3 | 9240 | |
37c41ab1 | 9241 | \0\b[index\0\b] |
ccc6cda3 JA |
9242 | * Menu: |
9243 | ||
e8ce775d | 9244 | * .: Bourne Shell Builtins. |
37c41ab1 | 9245 | (line 16) |
e8ce775d | 9246 | * :: Bourne Shell Builtins. |
37c41ab1 | 9247 | (line 11) |
e8ce775d | 9248 | * [: Bourne Shell Builtins. |
37c41ab1 CR |
9249 | (line 212) |
9250 | * alias: Bash Builtins. (line 11) | |
e8ce775d | 9251 | * bg: Job Control Builtins. |
37c41ab1 CR |
9252 | (line 7) |
9253 | * bind: Bash Builtins. (line 21) | |
e8ce775d | 9254 | * break: Bourne Shell Builtins. |
37c41ab1 | 9255 | (line 29) |
ed35cb4a CR |
9256 | * builtin: Bash Builtins. (line 98) |
9257 | * caller: Bash Builtins. (line 106) | |
e8ce775d | 9258 | * cd: Bourne Shell Builtins. |
37c41ab1 | 9259 | (line 36) |
ed35cb4a | 9260 | * command: Bash Builtins. (line 123) |
bb70624e | 9261 | * compgen: Programmable Completion Builtins. |
37c41ab1 | 9262 | (line 10) |
bb70624e | 9263 | * complete: Programmable Completion Builtins. |
37c41ab1 | 9264 | (line 28) |
6a8fd0ed | 9265 | * compopt: Programmable Completion Builtins. |
ed35cb4a | 9266 | (line 212) |
e8ce775d | 9267 | * continue: Bourne Shell Builtins. |
37c41ab1 | 9268 | (line 55) |
ed35cb4a | 9269 | * declare: Bash Builtins. (line 142) |
bb70624e | 9270 | * dirs: Directory Stack Builtins. |
37c41ab1 | 9271 | (line 7) |
e8ce775d | 9272 | * disown: Job Control Builtins. |
37c41ab1 | 9273 | (line 83) |
ed35cb4a CR |
9274 | * echo: Bash Builtins. (line 208) |
9275 | * enable: Bash Builtins. (line 260) | |
e8ce775d | 9276 | * eval: Bourne Shell Builtins. |
37c41ab1 | 9277 | (line 63) |
e8ce775d | 9278 | * exec: Bourne Shell Builtins. |
37c41ab1 | 9279 | (line 70) |
e8ce775d | 9280 | * exit: Bourne Shell Builtins. |
37c41ab1 | 9281 | (line 82) |
e8ce775d | 9282 | * export: Bourne Shell Builtins. |
37c41ab1 | 9283 | (line 88) |
cce855bc | 9284 | * fc: Bash History Builtins. |
37c41ab1 | 9285 | (line 10) |
e8ce775d | 9286 | * fg: Job Control Builtins. |
37c41ab1 | 9287 | (line 16) |
e8ce775d | 9288 | * getopts: Bourne Shell Builtins. |
37c41ab1 | 9289 | (line 103) |
e8ce775d | 9290 | * hash: Bourne Shell Builtins. |
37c41ab1 | 9291 | (line 145) |
ed35cb4a | 9292 | * help: Bash Builtins. (line 288) |
cce855bc | 9293 | * history: Bash History Builtins. |
37c41ab1 | 9294 | (line 39) |
e8ce775d | 9295 | * jobs: Job Control Builtins. |
37c41ab1 | 9296 | (line 25) |
e8ce775d | 9297 | * kill: Job Control Builtins. |
37c41ab1 | 9298 | (line 57) |
ed35cb4a CR |
9299 | * let: Bash Builtins. (line 308) |
9300 | * local: Bash Builtins. (line 315) | |
9301 | * logout: Bash Builtins. (line 325) | |
9302 | * mapfile: Bash Builtins. (line 329) | |
bb70624e | 9303 | * popd: Directory Stack Builtins. |
37c41ab1 | 9304 | (line 37) |
ed35cb4a | 9305 | * printf: Bash Builtins. (line 370) |
bb70624e | 9306 | * pushd: Directory Stack Builtins. |
37c41ab1 | 9307 | (line 58) |
e8ce775d | 9308 | * pwd: Bourne Shell Builtins. |
37c41ab1 | 9309 | (line 163) |
ed35cb4a | 9310 | * read: Bash Builtins. (line 395) |
e8ce775d | 9311 | * readonly: Bourne Shell Builtins. |
37c41ab1 | 9312 | (line 172) |
e8ce775d | 9313 | * return: Bourne Shell Builtins. |
37c41ab1 | 9314 | (line 187) |
d3ad40de | 9315 | * set: The Set Builtin. (line 11) |
e8ce775d | 9316 | * shift: Bourne Shell Builtins. |
37c41ab1 | 9317 | (line 200) |
d3ad40de | 9318 | * shopt: The Shopt Builtin. (line 9) |
ed35cb4a | 9319 | * source: Bash Builtins. (line 461) |
e8ce775d | 9320 | * suspend: Job Control Builtins. |
37c41ab1 | 9321 | (line 94) |
e8ce775d | 9322 | * test: Bourne Shell Builtins. |
37c41ab1 | 9323 | (line 212) |
e8ce775d | 9324 | * times: Bourne Shell Builtins. |
d7f49990 | 9325 | (line 280) |
e8ce775d | 9326 | * trap: Bourne Shell Builtins. |
d7f49990 | 9327 | (line 285) |
ed35cb4a CR |
9328 | * type: Bash Builtins. (line 465) |
9329 | * typeset: Bash Builtins. (line 496) | |
9330 | * ulimit: Bash Builtins. (line 502) | |
e8ce775d | 9331 | * umask: Bourne Shell Builtins. |
d7f49990 | 9332 | (line 326) |
ed35cb4a | 9333 | * unalias: Bash Builtins. (line 588) |
e8ce775d | 9334 | * unset: Bourne Shell Builtins. |
d7f49990 | 9335 | (line 343) |
e8ce775d | 9336 | * wait: Job Control Builtins. |
37c41ab1 | 9337 | (line 73) |
ccc6cda3 JA |
9338 | |
9339 | \1f | |
d3ad40de | 9340 | File: bashref.info, Node: Reserved Word Index, Next: Variable Index, Prev: Builtin Index, Up: Indexes |
ccc6cda3 | 9341 | |
d3ad40de CR |
9342 | D.2 Index of Shell Reserved Words |
9343 | ================================= | |
ccc6cda3 | 9344 | |
37c41ab1 | 9345 | \0\b[index\0\b] |
ccc6cda3 JA |
9346 | * Menu: |
9347 | ||
ed35cb4a | 9348 | * !: Pipelines. (line 9) |
cce855bc | 9349 | * [[: Conditional Constructs. |
ed35cb4a | 9350 | (line 117) |
cce855bc | 9351 | * ]]: Conditional Constructs. |
ed35cb4a | 9352 | (line 117) |
e8ce775d | 9353 | * case: Conditional Constructs. |
37c41ab1 CR |
9354 | (line 28) |
9355 | * do: Looping Constructs. (line 12) | |
9356 | * done: Looping Constructs. (line 12) | |
e8ce775d | 9357 | * elif: Conditional Constructs. |
37c41ab1 | 9358 | (line 7) |
e8ce775d | 9359 | * else: Conditional Constructs. |
37c41ab1 | 9360 | (line 7) |
e8ce775d | 9361 | * esac: Conditional Constructs. |
37c41ab1 | 9362 | (line 28) |
e8ce775d | 9363 | * fi: Conditional Constructs. |
37c41ab1 CR |
9364 | (line 7) |
9365 | * for: Looping Constructs. (line 29) | |
9366 | * function: Shell Functions. (line 13) | |
e8ce775d | 9367 | * if: Conditional Constructs. |
37c41ab1 | 9368 | (line 7) |
e8ce775d | 9369 | * in: Conditional Constructs. |
37c41ab1 | 9370 | (line 28) |
cce855bc | 9371 | * select: Conditional Constructs. |
ed35cb4a | 9372 | (line 76) |
e8ce775d | 9373 | * then: Conditional Constructs. |
37c41ab1 | 9374 | (line 7) |
ed35cb4a | 9375 | * time: Pipelines. (line 9) |
37c41ab1 CR |
9376 | * until: Looping Constructs. (line 12) |
9377 | * while: Looping Constructs. (line 20) | |
9378 | * {: Command Grouping. (line 21) | |
9379 | * }: Command Grouping. (line 21) | |
ccc6cda3 JA |
9380 | |
9381 | \1f | |
d3ad40de | 9382 | File: bashref.info, Node: Variable Index, Next: Function Index, Prev: Reserved Word Index, Up: Indexes |
ccc6cda3 | 9383 | |
d3ad40de CR |
9384 | D.3 Parameter and Variable Index |
9385 | ================================ | |
ccc6cda3 | 9386 | |
37c41ab1 | 9387 | \0\b[index\0\b] |
ccc6cda3 JA |
9388 | * Menu: |
9389 | ||
37c41ab1 CR |
9390 | * !: Special Parameters. (line 46) |
9391 | * #: Special Parameters. (line 30) | |
9392 | * $: Special Parameters. (line 42) | |
9393 | * *: Special Parameters. (line 9) | |
9394 | * -: Special Parameters. (line 37) | |
9395 | * 0: Special Parameters. (line 50) | |
9396 | * ?: Special Parameters. (line 33) | |
9397 | * @: Special Parameters. (line 19) | |
9398 | * _: Special Parameters. (line 59) | |
e8ce775d | 9399 | * auto_resume: Job Control Variables. |
37c41ab1 CR |
9400 | (line 6) |
9401 | * BASH: Bash Variables. (line 13) | |
d3ad40de CR |
9402 | * BASH_ARGC: Bash Variables. (line 21) |
9403 | * BASH_ARGV: Bash Variables. (line 31) | |
9404 | * BASH_COMMAND: Bash Variables. (line 41) | |
9405 | * BASH_ENV: Bash Variables. (line 46) | |
9406 | * BASH_EXECUTION_STRING: Bash Variables. (line 52) | |
9407 | * BASH_LINENO: Bash Variables. (line 55) | |
c2a47ea9 CR |
9408 | * BASH_REMATCH: Bash Variables. (line 64) |
9409 | * BASH_SOURCE: Bash Variables. (line 72) | |
9410 | * BASH_SUBSHELL: Bash Variables. (line 76) | |
9411 | * BASH_VERSINFO: Bash Variables. (line 80) | |
9412 | * BASH_VERSION: Bash Variables. (line 104) | |
d3ad40de | 9413 | * BASHPID: Bash Variables. (line 16) |
e8ce775d | 9414 | * bell-style: Readline Init File Syntax. |
1c72c0cd | 9415 | (line 38) |
eb2bb562 | 9416 | * bind-tty-special-chars: Readline Init File Syntax. |
1c72c0cd | 9417 | (line 45) |
e8ce775d | 9418 | * CDPATH: Bourne Shell Variables. |
37c41ab1 | 9419 | (line 9) |
c2a47ea9 | 9420 | * COLUMNS: Bash Variables. (line 107) |
e8ce775d | 9421 | * comment-begin: Readline Init File Syntax. |
1c72c0cd | 9422 | (line 50) |
c2a47ea9 CR |
9423 | * COMP_CWORD: Bash Variables. (line 112) |
9424 | * COMP_KEY: Bash Variables. (line 141) | |
9425 | * COMP_LINE: Bash Variables. (line 118) | |
9426 | * COMP_POINT: Bash Variables. (line 123) | |
9427 | * COMP_TYPE: Bash Variables. (line 131) | |
9428 | * COMP_WORDBREAKS: Bash Variables. (line 145) | |
9429 | * COMP_WORDS: Bash Variables. (line 151) | |
ed35cb4a | 9430 | * completion-prefix-display-length: Readline Init File Syntax. |
1c72c0cd | 9431 | (line 60) |
ed35cb4a CR |
9432 | * completion-query-items: Readline Init File Syntax. |
9433 | (line 67) | |
c2a47ea9 | 9434 | * COMPREPLY: Bash Variables. (line 158) |
e8ce775d | 9435 | * convert-meta: Readline Init File Syntax. |
ed35cb4a | 9436 | (line 77) |
c2a47ea9 | 9437 | * DIRSTACK: Bash Variables. (line 163) |
e8ce775d | 9438 | * disable-completion: Readline Init File Syntax. |
ed35cb4a | 9439 | (line 83) |
1c72c0cd | 9440 | * editing-mode: Readline Init File Syntax. |
ed35cb4a | 9441 | (line 88) |
c2a47ea9 | 9442 | * EMACS: Bash Variables. (line 173) |
e8ce775d | 9443 | * enable-keypad: Readline Init File Syntax. |
ed35cb4a | 9444 | (line 94) |
c2a47ea9 | 9445 | * EUID: Bash Variables. (line 178) |
e8ce775d | 9446 | * expand-tilde: Readline Init File Syntax. |
ed35cb4a | 9447 | (line 99) |
c2a47ea9 CR |
9448 | * FCEDIT: Bash Variables. (line 182) |
9449 | * FIGNORE: Bash Variables. (line 186) | |
9450 | * FUNCNAME: Bash Variables. (line 192) | |
9451 | * GLOBIGNORE: Bash Variables. (line 201) | |
9452 | * GROUPS: Bash Variables. (line 207) | |
9453 | * histchars: Bash Variables. (line 213) | |
9454 | * HISTCMD: Bash Variables. (line 228) | |
9455 | * HISTCONTROL: Bash Variables. (line 233) | |
9456 | * HISTFILE: Bash Variables. (line 249) | |
9457 | * HISTFILESIZE: Bash Variables. (line 253) | |
9458 | * HISTIGNORE: Bash Variables. (line 261) | |
f73dda09 | 9459 | * history-preserve-point: Readline Init File Syntax. |
ed35cb4a | 9460 | (line 103) |
6a8fd0ed | 9461 | * history-size: Readline Init File Syntax. |
ed35cb4a | 9462 | (line 109) |
c2a47ea9 CR |
9463 | * HISTSIZE: Bash Variables. (line 280) |
9464 | * HISTTIMEFORMAT: Bash Variables. (line 284) | |
e8ce775d | 9465 | * HOME: Bourne Shell Variables. |
37c41ab1 | 9466 | (line 13) |
e8ce775d | 9467 | * horizontal-scroll-mode: Readline Init File Syntax. |
ed35cb4a | 9468 | (line 114) |
c2a47ea9 CR |
9469 | * HOSTFILE: Bash Variables. (line 293) |
9470 | * HOSTNAME: Bash Variables. (line 304) | |
9471 | * HOSTTYPE: Bash Variables. (line 307) | |
e8ce775d | 9472 | * IFS: Bourne Shell Variables. |
37c41ab1 | 9473 | (line 18) |
c2a47ea9 | 9474 | * IGNOREEOF: Bash Variables. (line 310) |
e8ce775d | 9475 | * input-meta: Readline Init File Syntax. |
ed35cb4a | 9476 | (line 121) |
c2a47ea9 | 9477 | * INPUTRC: Bash Variables. (line 320) |
b72432fd | 9478 | * isearch-terminators: Readline Init File Syntax. |
6a8fd0ed | 9479 | (line 128) |
ed35cb4a CR |
9480 | * keymap: Readline Init File Syntax. |
9481 | (line 135) | |
c2a47ea9 CR |
9482 | * LANG: Bash Variables. (line 324) |
9483 | * LC_ALL: Bash Variables. (line 328) | |
9484 | * LC_COLLATE: Bash Variables. (line 332) | |
9485 | * LC_CTYPE: Bash Variables. (line 339) | |
37c41ab1 | 9486 | * LC_MESSAGES <1>: Locale Translation. (line 11) |
c2a47ea9 CR |
9487 | * LC_MESSAGES: Bash Variables. (line 344) |
9488 | * LC_NUMERIC: Bash Variables. (line 348) | |
9489 | * LINENO: Bash Variables. (line 352) | |
9490 | * LINES: Bash Variables. (line 356) | |
9491 | * MACHTYPE: Bash Variables. (line 361) | |
e8ce775d | 9492 | * MAIL: Bourne Shell Variables. |
37c41ab1 | 9493 | (line 22) |
c2a47ea9 | 9494 | * MAILCHECK: Bash Variables. (line 365) |
e8ce775d | 9495 | * MAILPATH: Bourne Shell Variables. |
37c41ab1 | 9496 | (line 27) |
e8ce775d | 9497 | * mark-modified-lines: Readline Init File Syntax. |
ed35cb4a | 9498 | (line 148) |
6a8fd0ed | 9499 | * mark-symlinked-directories: Readline Init File Syntax. |
ed35cb4a | 9500 | (line 153) |
6a8fd0ed | 9501 | * match-hidden-files: Readline Init File Syntax. |
ed35cb4a | 9502 | (line 158) |
e8ce775d | 9503 | * meta-flag: Readline Init File Syntax. |
ed35cb4a | 9504 | (line 121) |
c2a47ea9 | 9505 | * OLDPWD: Bash Variables. (line 373) |
e8ce775d | 9506 | * OPTARG: Bourne Shell Variables. |
37c41ab1 | 9507 | (line 34) |
c2a47ea9 | 9508 | * OPTERR: Bash Variables. (line 376) |
e8ce775d | 9509 | * OPTIND: Bourne Shell Variables. |
37c41ab1 | 9510 | (line 38) |
c2a47ea9 | 9511 | * OSTYPE: Bash Variables. (line 380) |
e8ce775d | 9512 | * output-meta: Readline Init File Syntax. |
ed35cb4a | 9513 | (line 165) |
6a8fd0ed | 9514 | * page-completions: Readline Init File Syntax. |
ed35cb4a | 9515 | (line 170) |
e8ce775d | 9516 | * PATH: Bourne Shell Variables. |
37c41ab1 | 9517 | (line 42) |
c2a47ea9 CR |
9518 | * PIPESTATUS: Bash Variables. (line 383) |
9519 | * POSIXLY_CORRECT: Bash Variables. (line 388) | |
9520 | * PPID: Bash Variables. (line 397) | |
9521 | * PROMPT_COMMAND: Bash Variables. (line 401) | |
e8ce775d | 9522 | * PS1: Bourne Shell Variables. |
37c41ab1 | 9523 | (line 48) |
e8ce775d | 9524 | * PS2: Bourne Shell Variables. |
37c41ab1 | 9525 | (line 53) |
c2a47ea9 CR |
9526 | * PS3: Bash Variables. (line 405) |
9527 | * PS4: Bash Variables. (line 410) | |
9528 | * PWD: Bash Variables. (line 416) | |
9529 | * RANDOM: Bash Variables. (line 419) | |
9530 | * REPLY: Bash Variables. (line 424) | |
ed35cb4a CR |
9531 | * revert-all-at-newline: Readline Init File Syntax. |
9532 | (line 180) | |
c2a47ea9 CR |
9533 | * SECONDS: Bash Variables. (line 427) |
9534 | * SHELL: Bash Variables. (line 433) | |
9535 | * SHELLOPTS: Bash Variables. (line 438) | |
9536 | * SHLVL: Bash Variables. (line 447) | |
e8ce775d | 9537 | * show-all-if-ambiguous: Readline Init File Syntax. |
ed35cb4a | 9538 | (line 186) |
1c72c0cd | 9539 | * show-all-if-unmodified: Readline Init File Syntax. |
ed35cb4a | 9540 | (line 192) |
37c41ab1 CR |
9541 | * TEXTDOMAIN: Locale Translation. (line 11) |
9542 | * TEXTDOMAINDIR: Locale Translation. (line 11) | |
c2a47ea9 CR |
9543 | * TIMEFORMAT: Bash Variables. (line 452) |
9544 | * TMOUT: Bash Variables. (line 490) | |
9545 | * TMPDIR: Bash Variables. (line 502) | |
9546 | * UID: Bash Variables. (line 506) | |
e8ce775d | 9547 | * visible-stats: Readline Init File Syntax. |
ed35cb4a | 9548 | (line 201) |
ccc6cda3 JA |
9549 | |
9550 | \1f | |
d3ad40de | 9551 | File: bashref.info, Node: Function Index, Next: Concept Index, Prev: Variable Index, Up: Indexes |
ccc6cda3 | 9552 | |
d3ad40de CR |
9553 | D.4 Function Index |
9554 | ================== | |
ccc6cda3 | 9555 | |
37c41ab1 | 9556 | \0\b[index\0\b] |
ccc6cda3 JA |
9557 | * Menu: |
9558 | ||
e8ce775d | 9559 | * abort (C-g): Miscellaneous Commands. |
37c41ab1 CR |
9560 | (line 10) |
9561 | * accept-line (Newline or Return): Commands For History. (line 6) | |
9562 | * backward-char (C-b): Commands For Moving. (line 15) | |
9563 | * backward-delete-char (Rubout): Commands For Text. (line 11) | |
9564 | * backward-kill-line (C-x Rubout): Commands For Killing. (line 9) | |
9565 | * backward-kill-word (M-<DEL>): Commands For Killing. (line 24) | |
9566 | * backward-word (M-b): Commands For Moving. (line 22) | |
9567 | * beginning-of-history (M-<): Commands For History. (line 20) | |
9568 | * beginning-of-line (C-a): Commands For Moving. (line 6) | |
9569 | * call-last-kbd-macro (C-x e): Keyboard Macros. (line 13) | |
9570 | * capitalize-word (M-c): Commands For Text. (line 46) | |
e8ce775d | 9571 | * character-search (C-]): Miscellaneous Commands. |
37c41ab1 | 9572 | (line 41) |
e8ce775d | 9573 | * character-search-backward (M-C-]): Miscellaneous Commands. |
37c41ab1 CR |
9574 | (line 46) |
9575 | * clear-screen (C-l): Commands For Moving. (line 26) | |
28ef6c31 | 9576 | * complete (<TAB>): Commands For Completion. |
37c41ab1 CR |
9577 | (line 6) |
9578 | * copy-backward-word (): Commands For Killing. (line 49) | |
9579 | * copy-forward-word (): Commands For Killing. (line 54) | |
9580 | * copy-region-as-kill (): Commands For Killing. (line 45) | |
9581 | * delete-char (C-d): Commands For Text. (line 6) | |
b72432fd | 9582 | * delete-char-or-list (): Commands For Completion. |
37c41ab1 CR |
9583 | (line 34) |
9584 | * delete-horizontal-space (): Commands For Killing. (line 37) | |
9585 | * digit-argument (M-0, M-1, ... M--): Numeric Arguments. (line 6) | |
ccc6cda3 | 9586 | * do-uppercase-version (M-a, M-b, M-X, ...): Miscellaneous Commands. |
37c41ab1 CR |
9587 | (line 14) |
9588 | * downcase-word (M-l): Commands For Text. (line 42) | |
e8ce775d | 9589 | * dump-functions (): Miscellaneous Commands. |
37c41ab1 | 9590 | (line 64) |
e8ce775d | 9591 | * dump-macros (): Miscellaneous Commands. |
37c41ab1 | 9592 | (line 76) |
e8ce775d | 9593 | * dump-variables (): Miscellaneous Commands. |
37c41ab1 CR |
9594 | (line 70) |
9595 | * end-kbd-macro (C-x )): Keyboard Macros. (line 9) | |
9596 | * end-of-history (M->): Commands For History. (line 23) | |
9597 | * end-of-line (C-e): Commands For Moving. (line 9) | |
e8ce775d | 9598 | * exchange-point-and-mark (C-x C-x): Miscellaneous Commands. |
37c41ab1 CR |
9599 | (line 36) |
9600 | * forward-backward-delete-char (): Commands For Text. (line 15) | |
9601 | * forward-char (C-f): Commands For Moving. (line 12) | |
9602 | * forward-search-history (C-s): Commands For History. (line 31) | |
9603 | * forward-word (M-f): Commands For Moving. (line 18) | |
9604 | * history-search-backward (): Commands For History. (line 51) | |
9605 | * history-search-forward (): Commands For History. (line 46) | |
e8ce775d | 9606 | * insert-comment (M-#): Miscellaneous Commands. |
37c41ab1 | 9607 | (line 51) |
e8ce775d | 9608 | * insert-completions (M-*): Commands For Completion. |
37c41ab1 CR |
9609 | (line 18) |
9610 | * kill-line (C-k): Commands For Killing. (line 6) | |
9611 | * kill-region (): Commands For Killing. (line 41) | |
9612 | * kill-whole-line (): Commands For Killing. (line 15) | |
9613 | * kill-word (M-d): Commands For Killing. (line 19) | |
cce855bc | 9614 | * menu-complete (): Commands For Completion. |
37c41ab1 CR |
9615 | (line 22) |
9616 | * next-history (C-n): Commands For History. (line 17) | |
ccc6cda3 | 9617 | * non-incremental-forward-search-history (M-n): Commands For History. |
37c41ab1 | 9618 | (line 41) |
ccc6cda3 | 9619 | * non-incremental-reverse-search-history (M-p): Commands For History. |
37c41ab1 CR |
9620 | (line 36) |
9621 | * overwrite-mode (): Commands For Text. (line 50) | |
e8ce775d | 9622 | * possible-completions (M-?): Commands For Completion. |
37c41ab1 | 9623 | (line 15) |
28ef6c31 | 9624 | * prefix-meta (<ESC>): Miscellaneous Commands. |
37c41ab1 CR |
9625 | (line 18) |
9626 | * previous-history (C-p): Commands For History. (line 13) | |
9627 | * quoted-insert (C-q or C-v): Commands For Text. (line 20) | |
e8ce775d | 9628 | * re-read-init-file (C-x C-r): Miscellaneous Commands. |
37c41ab1 CR |
9629 | (line 6) |
9630 | * redraw-current-line (): Commands For Moving. (line 30) | |
9631 | * reverse-search-history (C-r): Commands For History. (line 27) | |
e8ce775d | 9632 | * revert-line (M-r): Miscellaneous Commands. |
37c41ab1 CR |
9633 | (line 25) |
9634 | * self-insert (a, b, A, 1, !, ...): Commands For Text. (line 24) | |
e8ce775d | 9635 | * set-mark (C-@): Miscellaneous Commands. |
37c41ab1 CR |
9636 | (line 32) |
9637 | * start-kbd-macro (C-x (): Keyboard Macros. (line 6) | |
9638 | * transpose-chars (C-t): Commands For Text. (line 27) | |
9639 | * transpose-words (M-t): Commands For Text. (line 33) | |
28ef6c31 | 9640 | * undo (C-_ or C-x C-u): Miscellaneous Commands. |
37c41ab1 CR |
9641 | (line 22) |
9642 | * universal-argument (): Numeric Arguments. (line 10) | |
9643 | * unix-filename-rubout (): Commands For Killing. (line 32) | |
9644 | * unix-line-discard (C-u): Commands For Killing. (line 12) | |
9645 | * unix-word-rubout (C-w): Commands For Killing. (line 28) | |
9646 | * upcase-word (M-u): Commands For Text. (line 38) | |
9647 | * yank (C-y): Commands For Killing. (line 59) | |
eb2bb562 | 9648 | * yank-last-arg (M-. or M-_): Commands For History. (line 65) |
37c41ab1 CR |
9649 | * yank-nth-arg (M-C-y): Commands For History. (line 56) |
9650 | * yank-pop (M-y): Commands For Killing. (line 62) | |
ccc6cda3 JA |
9651 | |
9652 | \1f | |
d3ad40de | 9653 | File: bashref.info, Node: Concept Index, Prev: Function Index, Up: Indexes |
ccc6cda3 | 9654 | |
d3ad40de CR |
9655 | D.5 Concept Index |
9656 | ================= | |
ccc6cda3 | 9657 | |
37c41ab1 | 9658 | \0\b[index\0\b] |
ccc6cda3 JA |
9659 | * Menu: |
9660 | ||
37c41ab1 CR |
9661 | * alias expansion: Aliases. (line 6) |
9662 | * arithmetic evaluation: Shell Arithmetic. (line 6) | |
e8ce775d | 9663 | * arithmetic expansion: Arithmetic Expansion. |
37c41ab1 CR |
9664 | (line 6) |
9665 | * arithmetic, shell: Shell Arithmetic. (line 6) | |
9666 | * arrays: Arrays. (line 6) | |
9667 | * background: Job Control Basics. (line 6) | |
9668 | * Bash configuration: Basic Installation. (line 6) | |
9669 | * Bash installation: Basic Installation. (line 6) | |
e8ce775d | 9670 | * Bourne shell: Basic Shell Features. |
37c41ab1 CR |
9671 | (line 6) |
9672 | * brace expansion: Brace Expansion. (line 6) | |
ac18b312 | 9673 | * builtin: Definitions. (line 17) |
e8ce775d | 9674 | * command editing: Readline Bare Essentials. |
37c41ab1 | 9675 | (line 6) |
e8ce775d | 9676 | * command execution: Command Search and Execution. |
37c41ab1 | 9677 | (line 6) |
cce855bc | 9678 | * command expansion: Simple Command Expansion. |
37c41ab1 | 9679 | (line 6) |
e8ce775d | 9680 | * command history: Bash History Facilities. |
37c41ab1 | 9681 | (line 6) |
e8ce775d | 9682 | * command search: Command Search and Execution. |
37c41ab1 | 9683 | (line 6) |
e8ce775d | 9684 | * command substitution: Command Substitution. |
37c41ab1 | 9685 | (line 6) |
ed35cb4a | 9686 | * command timing: Pipelines. (line 9) |
37c41ab1 | 9687 | * commands, compound: Compound Commands. (line 6) |
e8ce775d | 9688 | * commands, conditional: Conditional Constructs. |
37c41ab1 CR |
9689 | (line 6) |
9690 | * commands, grouping: Command Grouping. (line 6) | |
9691 | * commands, lists: Lists. (line 6) | |
9692 | * commands, looping: Looping Constructs. (line 6) | |
9693 | * commands, pipelines: Pipelines. (line 6) | |
9694 | * commands, shell: Shell Commands. (line 6) | |
9695 | * commands, simple: Simple Commands. (line 6) | |
9696 | * comments, shell: Comments. (line 6) | |
bb70624e | 9697 | * completion builtins: Programmable Completion Builtins. |
37c41ab1 CR |
9698 | (line 6) |
9699 | * configuration: Basic Installation. (line 6) | |
ac18b312 | 9700 | * control operator: Definitions. (line 21) |
37c41ab1 | 9701 | * directory stack: The Directory Stack. (line 6) |
e8ce775d | 9702 | * editing command lines: Readline Bare Essentials. |
37c41ab1 CR |
9703 | (line 6) |
9704 | * environment: Environment. (line 6) | |
9705 | * evaluation, arithmetic: Shell Arithmetic. (line 6) | |
9706 | * event designators: Event Designators. (line 6) | |
cce855bc | 9707 | * execution environment: Command Execution Environment. |
37c41ab1 CR |
9708 | (line 6) |
9709 | * exit status <1>: Exit Status. (line 6) | |
ed35cb4a | 9710 | * exit status: Definitions. (line 26) |
37c41ab1 | 9711 | * expansion: Shell Expansions. (line 6) |
e8ce775d | 9712 | * expansion, arithmetic: Arithmetic Expansion. |
37c41ab1 CR |
9713 | (line 6) |
9714 | * expansion, brace: Brace Expansion. (line 6) | |
9715 | * expansion, filename: Filename Expansion. (line 9) | |
e8ce775d | 9716 | * expansion, parameter: Shell Parameter Expansion. |
37c41ab1 CR |
9717 | (line 6) |
9718 | * expansion, pathname: Filename Expansion. (line 9) | |
9719 | * expansion, tilde: Tilde Expansion. (line 6) | |
9720 | * expressions, arithmetic: Shell Arithmetic. (line 6) | |
e8ce775d | 9721 | * expressions, conditional: Bash Conditional Expressions. |
37c41ab1 | 9722 | (line 6) |
ed35cb4a CR |
9723 | * field: Definitions. (line 30) |
9724 | * filename: Definitions. (line 35) | |
37c41ab1 CR |
9725 | * filename expansion: Filename Expansion. (line 9) |
9726 | * foreground: Job Control Basics. (line 6) | |
9727 | * functions, shell: Shell Functions. (line 6) | |
cce855bc | 9728 | * history builtins: Bash History Builtins. |
37c41ab1 CR |
9729 | (line 6) |
9730 | * history events: Event Designators. (line 7) | |
9731 | * history expansion: History Interaction. (line 6) | |
e8ce775d | 9732 | * history list: Bash History Facilities. |
37c41ab1 | 9733 | (line 6) |
bb70624e | 9734 | * History, how to use: Programmable Completion Builtins. |
ed35cb4a CR |
9735 | (line 224) |
9736 | * identifier: Definitions. (line 51) | |
37c41ab1 CR |
9737 | * initialization file, readline: Readline Init File. (line 6) |
9738 | * installation: Basic Installation. (line 6) | |
e8ce775d | 9739 | * interaction, readline: Readline Interaction. |
37c41ab1 CR |
9740 | (line 6) |
9741 | * interactive shell <1>: Interactive Shells. (line 6) | |
ac18b312 | 9742 | * interactive shell: Invoking Bash. (line 127) |
37c41ab1 | 9743 | * internationalization: Locale Translation. (line 6) |
ed35cb4a | 9744 | * job: Definitions. (line 38) |
c2a47ea9 | 9745 | * job control <1>: Job Control Basics. (line 6) |
ed35cb4a | 9746 | * job control: Definitions. (line 42) |
e8ce775d | 9747 | * kill ring: Readline Killing Commands. |
37c41ab1 | 9748 | (line 19) |
e8ce775d | 9749 | * killing text: Readline Killing Commands. |
37c41ab1 CR |
9750 | (line 6) |
9751 | * localization: Locale Translation. (line 6) | |
ac18b312 | 9752 | * login shell: Invoking Bash. (line 124) |
37c41ab1 | 9753 | * matching, pattern: Pattern Matching. (line 6) |
ed35cb4a CR |
9754 | * metacharacter: Definitions. (line 46) |
9755 | * name: Definitions. (line 51) | |
37c41ab1 | 9756 | * native languages: Locale Translation. (line 6) |
e8ce775d | 9757 | * notation, readline: Readline Bare Essentials. |
37c41ab1 | 9758 | (line 6) |
ed35cb4a | 9759 | * operator, shell: Definitions. (line 57) |
e8ce775d | 9760 | * parameter expansion: Shell Parameter Expansion. |
37c41ab1 CR |
9761 | (line 6) |
9762 | * parameters: Shell Parameters. (line 6) | |
e8ce775d | 9763 | * parameters, positional: Positional Parameters. |
37c41ab1 CR |
9764 | (line 6) |
9765 | * parameters, special: Special Parameters. (line 6) | |
9766 | * pathname expansion: Filename Expansion. (line 9) | |
9767 | * pattern matching: Pattern Matching. (line 6) | |
9768 | * pipeline: Pipelines. (line 6) | |
9769 | * POSIX: Definitions. (line 9) | |
9770 | * POSIX Mode: Bash POSIX Mode. (line 6) | |
ed35cb4a CR |
9771 | * process group: Definitions. (line 61) |
9772 | * process group ID: Definitions. (line 65) | |
e8ce775d | 9773 | * process substitution: Process Substitution. |
37c41ab1 | 9774 | (line 6) |
bb70624e | 9775 | * programmable completion: Programmable Completion. |
37c41ab1 CR |
9776 | (line 6) |
9777 | * prompting: Printing a Prompt. (line 6) | |
9778 | * quoting: Quoting. (line 6) | |
9779 | * quoting, ANSI: ANSI-C Quoting. (line 6) | |
bb70624e | 9780 | * Readline, how to use: Job Control Variables. |
37c41ab1 CR |
9781 | (line 24) |
9782 | * redirection: Redirections. (line 6) | |
ed35cb4a | 9783 | * reserved word: Definitions. (line 69) |
e8ce775d | 9784 | * restricted shell: The Restricted Shell. |
37c41ab1 | 9785 | (line 6) |
ed35cb4a | 9786 | * return status: Definitions. (line 74) |
37c41ab1 CR |
9787 | * shell arithmetic: Shell Arithmetic. (line 6) |
9788 | * shell function: Shell Functions. (line 6) | |
9789 | * shell script: Shell Scripts. (line 6) | |
9790 | * shell variable: Shell Parameters. (line 6) | |
9791 | * shell, interactive: Interactive Shells. (line 6) | |
ed35cb4a | 9792 | * signal: Definitions. (line 77) |
37c41ab1 | 9793 | * signal handling: Signals. (line 6) |
c2a47ea9 | 9794 | * special builtin <1>: Special Builtins. (line 6) |
ed35cb4a | 9795 | * special builtin: Definitions. (line 81) |
37c41ab1 CR |
9796 | * startup files: Bash Startup Files. (line 6) |
9797 | * suspending jobs: Job Control Basics. (line 6) | |
9798 | * tilde expansion: Tilde Expansion. (line 6) | |
ed35cb4a | 9799 | * token: Definitions. (line 85) |
37c41ab1 CR |
9800 | * translation, native languages: Locale Translation. (line 6) |
9801 | * variable, shell: Shell Parameters. (line 6) | |
28ef6c31 | 9802 | * variables, readline: Readline Init File Syntax. |
1c72c0cd | 9803 | (line 37) |
ed35cb4a | 9804 | * word: Definitions. (line 89) |
37c41ab1 | 9805 | * word splitting: Word Splitting. (line 6) |
e8ce775d | 9806 | * yanking text: Readline Killing Commands. |
37c41ab1 | 9807 | (line 6) |
ccc6cda3 JA |
9808 | |
9809 | ||
9810 | \1f | |
9811 | Tag Table: | |
ed35cb4a CR |
9812 | Node: Top\7f1338 |
9813 | Node: Introduction\7f3167 | |
9814 | Node: What is Bash?\7f3395 | |
9815 | Node: What is a shell?\7f4508 | |
9816 | Node: Definitions\7f7048 | |
9817 | Node: Basic Shell Features\7f9828 | |
9818 | Node: Shell Syntax\7f11047 | |
9819 | Node: Shell Operation\7f12077 | |
9820 | Node: Quoting\7f13371 | |
9821 | Node: Escape Character\7f14674 | |
9822 | Node: Single Quotes\7f15159 | |
9823 | Node: Double Quotes\7f15507 | |
9824 | Node: ANSI-C Quoting\7f16632 | |
9825 | Node: Locale Translation\7f17588 | |
9826 | Node: Comments\7f18484 | |
9827 | Node: Shell Commands\7f19102 | |
9828 | Node: Simple Commands\7f19868 | |
9829 | Node: Pipelines\7f20499 | |
9830 | Node: Lists\7f22755 | |
9831 | Node: Compound Commands\7f24484 | |
9832 | Node: Looping Constructs\7f25268 | |
9833 | Node: Conditional Constructs\7f27715 | |
9834 | Node: Command Grouping\7f35721 | |
9835 | Node: Shell Functions\7f37200 | |
9836 | Node: Shell Parameters\7f41661 | |
9837 | Node: Positional Parameters\7f43991 | |
9838 | Node: Special Parameters\7f44891 | |
9839 | Node: Shell Expansions\7f47855 | |
9840 | Node: Brace Expansion\7f49780 | |
9841 | Node: Tilde Expansion\7f52533 | |
9842 | Node: Shell Parameter Expansion\7f54884 | |
9843 | Node: Command Substitution\7f62584 | |
9844 | Node: Arithmetic Expansion\7f63917 | |
9845 | Node: Process Substitution\7f64767 | |
9846 | Node: Word Splitting\7f65817 | |
9847 | Node: Filename Expansion\7f67440 | |
9848 | Node: Pattern Matching\7f69580 | |
9849 | Node: Quote Removal\7f73219 | |
9850 | Node: Redirections\7f73514 | |
9851 | Node: Executing Commands\7f81657 | |
9852 | Node: Simple Command Expansion\7f82327 | |
9853 | Node: Command Search and Execution\7f84257 | |
9854 | Node: Command Execution Environment\7f86594 | |
9855 | Node: Environment\7f89393 | |
9856 | Node: Exit Status\7f91053 | |
9857 | Node: Signals\7f92674 | |
9858 | Node: Shell Scripts\7f94642 | |
9859 | Node: Shell Builtin Commands\7f97160 | |
9860 | Node: Bourne Shell Builtins\7f98837 | |
9861 | Node: Bash Builtins\7f116067 | |
9862 | Node: Modifying Shell Behavior\7f138853 | |
9863 | Node: The Set Builtin\7f139198 | |
9864 | Node: The Shopt Builtin\7f148046 | |
9865 | Node: Special Builtins\7f158908 | |
9866 | Node: Shell Variables\7f159887 | |
9867 | Node: Bourne Shell Variables\7f160327 | |
9868 | Node: Bash Variables\7f162308 | |
9869 | Node: Bash Features\7f183680 | |
9870 | Node: Invoking Bash\7f184563 | |
9871 | Node: Bash Startup Files\7f190372 | |
9872 | Node: Interactive Shells\7f195341 | |
9873 | Node: What is an Interactive Shell?\7f195751 | |
9874 | Node: Is this Shell Interactive?\7f196400 | |
9875 | Node: Interactive Shell Behavior\7f197215 | |
9876 | Node: Bash Conditional Expressions\7f200495 | |
9877 | Node: Shell Arithmetic\7f204074 | |
9878 | Node: Aliases\7f206820 | |
9879 | Node: Arrays\7f209392 | |
9880 | Node: The Directory Stack\7f212741 | |
9881 | Node: Directory Stack Builtins\7f213455 | |
9882 | Node: Printing a Prompt\7f216347 | |
9883 | Node: The Restricted Shell\7f219061 | |
9884 | Node: Bash POSIX Mode\7f220893 | |
9885 | Node: Job Control\7f228652 | |
9886 | Node: Job Control Basics\7f229112 | |
9887 | Node: Job Control Builtins\7f233621 | |
9888 | Node: Job Control Variables\7f237948 | |
9889 | Node: Command Line Editing\7f239106 | |
9890 | Node: Introduction and Notation\7f240101 | |
9891 | Node: Readline Interaction\7f241723 | |
9892 | Node: Readline Bare Essentials\7f242914 | |
9893 | Node: Readline Movement Commands\7f244703 | |
9894 | Node: Readline Killing Commands\7f245668 | |
9895 | Node: Readline Arguments\7f247588 | |
9896 | Node: Searching\7f248632 | |
9897 | Node: Readline Init File\7f250818 | |
9898 | Node: Readline Init File Syntax\7f251965 | |
9899 | Node: Conditional Init Constructs\7f265199 | |
9900 | Node: Sample Init File\7f267732 | |
9901 | Node: Bindable Readline Commands\7f270849 | |
9902 | Node: Commands For Moving\7f272056 | |
9903 | Node: Commands For History\7f272917 | |
9904 | Node: Commands For Text\7f276072 | |
9905 | Node: Commands For Killing\7f278745 | |
9906 | Node: Numeric Arguments\7f280887 | |
9907 | Node: Commands For Completion\7f282026 | |
9908 | Node: Keyboard Macros\7f285793 | |
9909 | Node: Miscellaneous Commands\7f286364 | |
9910 | Node: Readline vi Mode\7f291675 | |
9911 | Node: Programmable Completion\7f292589 | |
9912 | Node: Programmable Completion Builtins\7f298422 | |
9913 | Node: Using History Interactively\7f306805 | |
9914 | Node: Bash History Facilities\7f307489 | |
9915 | Node: Bash History Builtins\7f310403 | |
9916 | Node: History Interaction\7f314260 | |
9917 | Node: Event Designators\7f316965 | |
9918 | Node: Word Designators\7f317980 | |
9919 | Node: Modifiers\7f319619 | |
9920 | Node: Installing Bash\7f321023 | |
9921 | Node: Basic Installation\7f322160 | |
9922 | Node: Compilers and Options\7f324852 | |
9923 | Node: Compiling For Multiple Architectures\7f325593 | |
9924 | Node: Installation Names\7f327257 | |
9925 | Node: Specifying the System Type\7f328075 | |
9926 | Node: Sharing Defaults\7f328791 | |
9927 | Node: Operation Controls\7f329464 | |
9928 | Node: Optional Features\7f330422 | |
9929 | Node: Reporting Bugs\7f339353 | |
9930 | Node: Major Differences From The Bourne Shell\7f340547 | |
9931 | Node: GNU Free Documentation License\7f357234 | |
9932 | Node: Indexes\7f379695 | |
9933 | Node: Builtin Index\7f380149 | |
9934 | Node: Reserved Word Index\7f386903 | |
9935 | Node: Variable Index\7f389351 | |
9936 | Node: Function Index\7f400938 | |
9937 | Node: Concept Index\7f407670 | |
ccc6cda3 JA |
9938 | \1f |
9939 | End Tag Table |