Jari Aalto | 17345e5 | 2009-02-19 22:21:29 +0000 | [diff] [blame] | 1 | <HTML><HEAD> |
| 2 | <TITLE>BASH(1) Manual Page</TITLE> |
| 3 | </HEAD> |
| 4 | <BODY><TABLE WIDTH=100%> |
| 5 | <TR> |
| 6 | <TH ALIGN=LEFT width=33%>BASH(1)<TH ALIGN=CENTER width=33%>2008 December 29<TH ALIGN=RIGHT width=33%>BASH(1) |
| 7 | </TR> |
| 8 | </TABLE> |
| 9 | <BR><A HREF="#index">Index</A> |
| 10 | <HR> |
| 11 | |
| 12 | |
| 13 | |
| 14 | |
| 15 | |
| 16 | |
| 17 | |
| 18 | |
| 19 | |
| 20 | |
| 21 | |
| 22 | |
| 23 | |
| 24 | |
| 25 | |
| 26 | |
| 27 | |
| 28 | |
| 29 | |
| 30 | <A NAME="lbAB"> </A> |
| 31 | <H3>NAME</H3> |
| 32 | |
| 33 | bash - GNU Bourne-Again SHell |
| 34 | <A NAME="lbAC"> </A> |
| 35 | <H3>SYNOPSIS</H3> |
| 36 | |
| 37 | <B>bash</B> |
| 38 | |
| 39 | [options] |
| 40 | [file] |
| 41 | <A NAME="lbAD"> </A> |
| 42 | <H3>COPYRIGHT</H3> |
| 43 | |
| 44 | |
| 45 | Bash is Copyright © 1989-2009 by the Free Software Foundation, Inc. |
| 46 | <A NAME="lbAE"> </A> |
| 47 | <H3>DESCRIPTION</H3> |
| 48 | |
| 49 | <B>Bash</B> |
| 50 | |
| 51 | is an <B>sh</B>-compatible command language interpreter that |
| 52 | executes commands read from the standard input or from a file. |
| 53 | <B>Bash</B> |
| 54 | |
| 55 | also incorporates useful features from the <I>Korn</I> and <I>C</I> |
| 56 | shells (<B>ksh</B> and <B>csh</B>). |
| 57 | <P> |
| 58 | |
| 59 | <B>Bash</B> |
| 60 | |
| 61 | is intended to be a conformant implementation of the |
| 62 | Shell and Utilities portion of the IEEE POSIX specification |
| 63 | (IEEE Standard 1003.1). |
| 64 | <B>Bash</B> |
| 65 | |
| 66 | can be configured to be POSIX-conformant by default. |
| 67 | <A NAME="lbAF"> </A> |
| 68 | <H3>OPTIONS</H3> |
| 69 | |
| 70 | In addition to the single-character shell options documented in the |
| 71 | description of the <B>set</B> builtin command, <B>bash</B> |
| 72 | interprets the following options when it is invoked: |
| 73 | <P> |
| 74 | |
| 75 | |
| 76 | <DL COMPACT> |
| 77 | <DT><B>-c</B><I> string</I> |
| 78 | |
| 79 | <DD> |
| 80 | If the |
| 81 | <B>-c</B> |
| 82 | |
| 83 | option is present, then commands are read from |
| 84 | <I>string</I>. |
| 85 | |
| 86 | If there are arguments after the |
| 87 | <I>string</I>, |
| 88 | |
| 89 | they are assigned to the positional parameters, starting with |
| 90 | <B>$0</B>. |
| 91 | |
| 92 | <DT><B>-i</B> |
| 93 | |
| 94 | <DD> |
| 95 | If the |
| 96 | <B>-i</B> |
| 97 | |
| 98 | option is present, the shell is |
| 99 | <I>interactive</I>. |
| 100 | |
| 101 | <DT><B>-l</B> |
| 102 | |
| 103 | <DD> |
| 104 | Make |
| 105 | <B>bash</B> |
| 106 | |
| 107 | act as if it had been invoked as a login shell (see |
| 108 | <FONT SIZE=-1><B>INVOCATION</B> |
| 109 | |
| 110 | </FONT> |
| 111 | below). |
| 112 | <DT><B>-r</B> |
| 113 | |
| 114 | <DD> |
| 115 | If the |
| 116 | <B>-r</B> |
| 117 | |
| 118 | option is present, the shell becomes |
| 119 | <I>restricted</I> |
| 120 | |
| 121 | (see |
| 122 | <FONT SIZE=-1><B>RESTRICTED SHELL</B> |
| 123 | |
| 124 | </FONT> |
| 125 | below). |
| 126 | <DT><B>-s</B> |
| 127 | |
| 128 | <DD> |
| 129 | If the |
| 130 | <B>-s</B> |
| 131 | |
| 132 | option is present, or if no arguments remain after option |
| 133 | processing, then commands are read from the standard input. |
| 134 | This option allows the positional parameters to be set |
| 135 | when invoking an interactive shell. |
| 136 | <DT><B>-D</B> |
| 137 | |
| 138 | <DD> |
| 139 | A list of all double-quoted strings preceded by <B>$</B> |
| 140 | is printed on the standard output. |
| 141 | These are the strings that |
| 142 | are subject to language translation when the current locale |
| 143 | is not <B>C</B> or <B>POSIX</B>. |
| 144 | This implies the <B>-n</B> option; no commands will be executed. |
| 145 | <DT><B>[-+]O [</B><I>shopt_option</I>] |
| 146 | |
| 147 | <DD> |
| 148 | <I>shopt_option</I> is one of the shell options accepted by the |
| 149 | <B>shopt</B> builtin (see |
| 150 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 151 | |
| 152 | </FONT> |
| 153 | below). |
| 154 | If <I>shopt_option</I> is present, <B>-O</B> sets the value of that option; |
| 155 | <B>+O</B> unsets it. |
| 156 | If <I>shopt_option</I> is not supplied, the names and values of the shell |
| 157 | options accepted by <B>shopt</B> are printed on the standard output. |
| 158 | If the invocation option is <B>+O</B>, the output is displayed in a format |
| 159 | that may be reused as input. |
| 160 | <DT><B>--</B> |
| 161 | |
| 162 | <DD> |
| 163 | A |
| 164 | <B>--</B> |
| 165 | |
| 166 | signals the end of options and disables further option processing. |
| 167 | Any arguments after the |
| 168 | <B>--</B> |
| 169 | |
| 170 | are treated as filenames and arguments. An argument of |
| 171 | <B>-</B> |
| 172 | |
| 173 | is equivalent to <B>--</B>. |
| 174 | |
| 175 | </DL> |
| 176 | <P> |
| 177 | |
| 178 | <B>Bash</B> |
| 179 | |
| 180 | also interprets a number of multi-character options. |
| 181 | These options must appear on the command line before the |
| 182 | single-character options to be recognized. |
| 183 | <P> |
| 184 | |
| 185 | |
| 186 | <DL COMPACT> |
| 187 | <DT><B>--debugger</B> |
| 188 | |
| 189 | <DD> |
| 190 | Arrange for the debugger profile to be executed before the shell |
| 191 | starts. |
| 192 | Turns on extended debugging mode (see the description of the |
| 193 | <B>extdebug</B> |
| 194 | |
| 195 | option to the |
| 196 | <B>shopt</B> |
| 197 | |
| 198 | builtin below) |
| 199 | and shell function tracing (see the description of the |
| 200 | <B>-o functrace</B> option to the |
| 201 | <B>set</B> |
| 202 | |
| 203 | builtin below). |
| 204 | <DT><B>--dump-po-strings</B> |
| 205 | |
| 206 | <DD> |
| 207 | Equivalent to <B>-D</B>, but the output is in the GNU <I>gettext</I> |
| 208 | <B>po</B> (portable object) file format. |
| 209 | <DT><B>--dump-strings</B> |
| 210 | |
| 211 | <DD> |
| 212 | Equivalent to <B>-D</B>. |
| 213 | <DT><B>--help</B> |
| 214 | |
| 215 | <DD> |
| 216 | Display a usage message on standard output and exit successfully. |
| 217 | <DT><B>--init-file</B> <I>file</I><DD> |
| 218 | |
| 219 | <DT><B>--rcfile</B> <I>file</I><DD> |
| 220 | |
| 221 | Execute commands from |
| 222 | <I>file</I> |
| 223 | |
| 224 | instead of the standard personal initialization file |
| 225 | <A HREF="file:~/.bashrc"><I>~/.bashrc</I></A> |
| 226 | |
| 227 | if the shell is interactive (see |
| 228 | <FONT SIZE=-1><B>INVOCATION</B> |
| 229 | |
| 230 | </FONT> |
| 231 | below). |
| 232 | <DT><B>--login</B> |
| 233 | |
| 234 | <DD> |
| 235 | Equivalent to <B>-l</B>. |
| 236 | <DT><B>--noediting</B> |
| 237 | |
| 238 | <DD> |
| 239 | Do not use the GNU |
| 240 | <B>readline</B> |
| 241 | |
| 242 | library to read command lines when the shell is interactive. |
| 243 | <DT><B>--noprofile</B> |
| 244 | |
| 245 | <DD> |
| 246 | Do not read either the system-wide startup file |
| 247 | |
| 248 | <A HREF="file:/etc/profile"><I>/etc/profile</I></A> |
| 249 | |
| 250 | or any of the personal initialization files |
| 251 | <A HREF="file:~/.bash_profile"><I>~/.bash_profile</I></A>, |
| 252 | |
| 253 | <A HREF="file:~/.bash_login"><I>~/.bash_login</I></A>, |
| 254 | |
| 255 | or |
| 256 | <A HREF="file:~/.profile"><I>~/.profile</I></A>. |
| 257 | |
| 258 | By default, |
| 259 | <B>bash</B> |
| 260 | |
| 261 | reads these files when it is invoked as a login shell (see |
| 262 | <FONT SIZE=-1><B>INVOCATION</B> |
| 263 | |
| 264 | </FONT> |
| 265 | below). |
| 266 | <DT><B>--norc</B> |
| 267 | |
| 268 | <DD> |
| 269 | Do not read and execute the personal initialization file |
| 270 | <A HREF="file:~/.bashrc"><I>~/.bashrc</I></A> |
| 271 | |
| 272 | if the shell is interactive. |
| 273 | This option is on by default if the shell is invoked as |
| 274 | <B>sh</B>. |
| 275 | |
| 276 | <DT><B>--posix</B> |
| 277 | |
| 278 | <DD> |
| 279 | Change the behavior of <B>bash</B> where the default operation differs |
| 280 | from the POSIX standard to match the standard (<I>posix mode</I>). |
| 281 | <DT><B>--restricted</B> |
| 282 | |
| 283 | <DD> |
| 284 | The shell becomes restricted (see |
| 285 | <FONT SIZE=-1><B>RESTRICTED SHELL</B> |
| 286 | |
| 287 | </FONT> |
| 288 | below). |
| 289 | <DT><B>--verbose</B> |
| 290 | |
| 291 | <DD> |
| 292 | Equivalent to <B>-v</B>. |
| 293 | <DT><B>--version</B> |
| 294 | |
| 295 | <DD> |
| 296 | Show version information for this instance of |
| 297 | <B>bash</B> |
| 298 | |
| 299 | on the standard output and exit successfully. |
| 300 | |
| 301 | </DL> |
| 302 | <A NAME="lbAG"> </A> |
| 303 | <H3>ARGUMENTS</H3> |
| 304 | |
| 305 | If arguments remain after option processing, and neither the |
| 306 | <B>-c</B> |
| 307 | |
| 308 | nor the |
| 309 | <B>-s</B> |
| 310 | |
| 311 | option has been supplied, the first argument is assumed to |
| 312 | be the name of a file containing shell commands. |
| 313 | If |
| 314 | <B>bash</B> |
| 315 | |
| 316 | is invoked in this fashion, |
| 317 | <B>$0</B> |
| 318 | |
| 319 | is set to the name of the file, and the positional parameters |
| 320 | are set to the remaining arguments. |
| 321 | <B>Bash</B> |
| 322 | |
| 323 | reads and executes commands from this file, then exits. |
| 324 | <B>Bash</B>'s exit status is the exit status of the last command |
| 325 | executed in the script. |
| 326 | If no commands are executed, the exit status is 0. |
| 327 | An attempt is first made to open the file in the current directory, and, |
| 328 | if no file is found, then the shell searches the directories in |
| 329 | <FONT SIZE=-1><B>PATH</B> |
| 330 | |
| 331 | </FONT> |
| 332 | for the script. |
| 333 | <A NAME="lbAH"> </A> |
| 334 | <H3>INVOCATION</H3> |
| 335 | |
| 336 | A <I>login shell</I> is one whose first character of argument zero is a |
| 337 | <B>-</B>, |
| 338 | |
| 339 | or one started with the |
| 340 | <B>--login</B> |
| 341 | |
| 342 | option. |
| 343 | <P> |
| 344 | |
| 345 | An <I>interactive</I> shell is one started without non-option arguments |
| 346 | and without the |
| 347 | <B>-c</B> |
| 348 | |
| 349 | option |
| 350 | whose standard input and error are |
| 351 | both connected to terminals (as determined by |
| 352 | <I>isatty</I>(3)), |
| 353 | |
| 354 | or one started with the |
| 355 | <B>-i</B> |
| 356 | |
| 357 | option. |
| 358 | <FONT SIZE=-1><B>PS1</B> |
| 359 | |
| 360 | </FONT> |
| 361 | is set and |
| 362 | <B>$-</B> |
| 363 | |
| 364 | includes |
| 365 | <B>i</B> |
| 366 | |
| 367 | if |
| 368 | <B>bash</B> |
| 369 | |
| 370 | is interactive, |
| 371 | allowing a shell script or a startup file to test this state. |
| 372 | <P> |
| 373 | |
| 374 | The following paragraphs describe how |
| 375 | <B>bash</B> |
| 376 | |
| 377 | executes its startup files. |
| 378 | If any of the files exist but cannot be read, |
| 379 | <B>bash</B> |
| 380 | |
| 381 | reports an error. |
| 382 | Tildes are expanded in file names as described below under |
| 383 | <B>Tilde Expansion</B> |
| 384 | |
| 385 | in the |
| 386 | <FONT SIZE=-1><B>EXPANSION</B> |
| 387 | |
| 388 | </FONT> |
| 389 | section. |
| 390 | <P> |
| 391 | |
| 392 | When |
| 393 | <B>bash</B> |
| 394 | |
| 395 | is invoked as an interactive login shell, or as a non-interactive shell |
| 396 | with the <B>--login</B> option, it first reads and |
| 397 | executes commands from the file <A HREF="file:/etc/profile"><I>/etc/profile</I></A>, if that |
| 398 | file exists. |
| 399 | After reading that file, it looks for <A HREF="file:~/.bash_profile"><I>~/.bash_profile</I></A>, |
| 400 | <A HREF="file:~/.bash_login"><I>~/.bash_login</I></A>, and <A HREF="file:~/.profile"><I>~/.profile</I></A>, in that order, and reads |
| 401 | and executes commands from the first one that exists and is readable. |
| 402 | The |
| 403 | <B>--noprofile</B> |
| 404 | |
| 405 | option may be used when the shell is started to inhibit this behavior. |
| 406 | <P> |
| 407 | |
| 408 | When a login shell exits, |
| 409 | <B>bash</B> |
| 410 | |
| 411 | reads and executes commands from the file <A HREF="file:~/.bash_logout"><I>~/.bash_logout</I></A>, if it |
| 412 | exists. |
| 413 | <P> |
| 414 | |
| 415 | When an interactive shell that is not a login shell is started, |
| 416 | <B>bash</B> |
| 417 | |
| 418 | reads and executes commands from <A HREF="file:~/.bashrc"><I>~/.bashrc</I></A>, if that file exists. |
| 419 | This may be inhibited by using the |
| 420 | <B>--norc</B> |
| 421 | |
| 422 | option. |
| 423 | The <B>--rcfile</B> <I>file</I> option will force |
| 424 | <B>bash</B> |
| 425 | |
| 426 | to read and execute commands from <I>file</I> instead of <A HREF="file:~/.bashrc"><I>~/.bashrc</I></A>. |
| 427 | <P> |
| 428 | |
| 429 | When |
| 430 | <B>bash</B> |
| 431 | |
| 432 | is started non-interactively, to run a shell script, for example, it |
| 433 | looks for the variable |
| 434 | <FONT SIZE=-1><B>BASH_ENV</B> |
| 435 | |
| 436 | </FONT> |
| 437 | in the environment, expands its value if it appears there, and uses the |
| 438 | expanded value as the name of a file to read and execute. |
| 439 | <B>Bash</B> |
| 440 | |
| 441 | behaves as if the following command were executed: |
| 442 | <P> |
| 443 | <DL COMPACT><DT><DD> |
| 444 | <TT>if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi</TT> |
| 445 | |
| 446 | </DL> |
| 447 | |
| 448 | <P> |
| 449 | but the value of the |
| 450 | <FONT SIZE=-1><B>PATH</B> |
| 451 | |
| 452 | </FONT> |
| 453 | variable is not used to search for the file name. |
| 454 | <P> |
| 455 | |
| 456 | If |
| 457 | <B>bash</B> |
| 458 | |
| 459 | is invoked with the name |
| 460 | <B>sh</B>, |
| 461 | |
| 462 | it tries to mimic the startup behavior of historical versions of |
| 463 | <B>sh</B> |
| 464 | |
| 465 | as closely as possible, |
| 466 | while conforming to the POSIX standard as well. |
| 467 | When invoked as an interactive login shell, or a non-interactive |
| 468 | shell with the <B>--login</B> option, it first attempts to |
| 469 | read and execute commands from |
| 470 | <A HREF="file:/etc/profile"><I>/etc/profile</I></A> |
| 471 | |
| 472 | and |
| 473 | <A HREF="file:~/.profile"><I>~/.profile</I></A>, |
| 474 | |
| 475 | in that order. |
| 476 | The |
| 477 | <B>--noprofile</B> |
| 478 | |
| 479 | option may be used to inhibit this behavior. |
| 480 | When invoked as an interactive shell with the name |
| 481 | <B>sh</B>, |
| 482 | |
| 483 | <B>bash</B> |
| 484 | |
| 485 | looks for the variable |
| 486 | <FONT SIZE=-1><B>ENV</B>, |
| 487 | |
| 488 | </FONT> |
| 489 | expands its value if it is defined, and uses the |
| 490 | expanded value as the name of a file to read and execute. |
| 491 | Since a shell invoked as |
| 492 | <B>sh</B> |
| 493 | |
| 494 | does not attempt to read and execute commands from any other startup |
| 495 | files, the |
| 496 | <B>--rcfile</B> |
| 497 | |
| 498 | option has no effect. |
| 499 | A non-interactive shell invoked with the name |
| 500 | <B>sh</B> |
| 501 | |
| 502 | does not attempt to read any other startup files. |
| 503 | When invoked as |
| 504 | <B>sh</B>, |
| 505 | |
| 506 | <B>bash</B> |
| 507 | |
| 508 | enters |
| 509 | <I>posix</I> |
| 510 | |
| 511 | mode after the startup files are read. |
| 512 | <P> |
| 513 | |
| 514 | When |
| 515 | <B>bash</B> |
| 516 | |
| 517 | is started in |
| 518 | <I>posix</I> |
| 519 | |
| 520 | mode, as with the |
| 521 | <B>--posix</B> |
| 522 | |
| 523 | command line option, it follows the POSIX standard for startup files. |
| 524 | In this mode, interactive shells expand the |
| 525 | <FONT SIZE=-1><B>ENV</B> |
| 526 | |
| 527 | </FONT> |
| 528 | variable and commands are read and executed from the file |
| 529 | whose name is the expanded value. |
| 530 | No other startup files are read. |
| 531 | <P> |
| 532 | |
| 533 | <B>Bash</B> |
| 534 | |
| 535 | attempts to determine when it is being run with its standard input |
| 536 | connected to a a network connection, as if by the remote shell |
| 537 | daemon, usually <I>rshd</I>, or the secure shell daemon <I>sshd</I>. |
| 538 | If |
| 539 | <B>bash</B> |
| 540 | |
| 541 | determines it is being run in this fashion, it reads and executes |
| 542 | commands from <A HREF="file:~/.bashrc"><I>~/.bashrc</I></A>, if that file exists and is readable. |
| 543 | It will not do this if invoked as <B>sh</B>. |
| 544 | The |
| 545 | <B>--norc</B> |
| 546 | |
| 547 | option may be used to inhibit this behavior, and the |
| 548 | <B>--rcfile</B> |
| 549 | |
| 550 | option may be used to force another file to be read, but |
| 551 | <I>rshd</I> does not generally invoke the shell with those options |
| 552 | or allow them to be specified. |
| 553 | <P> |
| 554 | |
| 555 | If the shell is started with the effective user (group) id not equal to the |
| 556 | real user (group) id, and the <B>-p</B> option is not supplied, no startup |
| 557 | files are read, shell functions are not inherited from the environment, the |
| 558 | <FONT SIZE=-1><B>SHELLOPTS</B> |
| 559 | |
| 560 | </FONT> |
| 561 | variable, if it appears in the environment, is ignored, |
| 562 | and the effective user id is set to the real user id. |
| 563 | If the <B>-p</B> option is supplied at invocation, the startup behavior is |
| 564 | the same, but the effective user id is not reset. |
| 565 | <A NAME="lbAI"> </A> |
| 566 | <H3>DEFINITIONS</H3> |
| 567 | |
| 568 | <P> |
| 569 | |
| 570 | The following definitions are used throughout the rest of this |
| 571 | document. |
| 572 | |
| 573 | <DL COMPACT> |
| 574 | <DT><B>blank </B> |
| 575 | |
| 576 | <DD> |
| 577 | A space or tab. |
| 578 | <DT><B>word</B> |
| 579 | |
| 580 | <DD> |
| 581 | A sequence of characters considered as a single unit by the shell. |
| 582 | Also known as a |
| 583 | <B>token</B>. |
| 584 | |
| 585 | <DT><B>name</B> |
| 586 | |
| 587 | <DD> |
| 588 | A |
| 589 | <I>word</I> |
| 590 | |
| 591 | consisting only of alphanumeric characters and underscores, and |
| 592 | beginning with an alphabetic character or an underscore. Also |
| 593 | referred to as an |
| 594 | <B>identifier</B>. |
| 595 | |
| 596 | <DT><B>metacharacter</B> |
| 597 | |
| 598 | <DD> |
| 599 | A character that, when unquoted, separates words. One of the following: |
| 600 | <BR> |
| 601 | |
| 602 | <DL COMPACT><DT><DD> |
| 603 | <P> |
| 604 | |
| 605 | <B>| & ; ( ) < > space tab</B> |
| 606 | |
| 607 | </DL> |
| 608 | |
| 609 | </DL> |
| 610 | <P> |
| 611 | |
| 612 | <DL COMPACT> |
| 613 | <DT><B>control operator</B> |
| 614 | |
| 615 | <DD> |
| 616 | A <I>token</I> that performs a control function. It is one of the following |
| 617 | symbols: |
| 618 | <DL COMPACT><DT><DD> |
| 619 | <P> |
| 620 | |
| 621 | <B>|| & && ; ;; ( ) | |& <newline></B> |
| 622 | |
| 623 | </DL> |
| 624 | |
| 625 | |
| 626 | </DL> |
| 627 | <A NAME="lbAJ"> </A> |
| 628 | <H3>RESERVED WORDS</H3> |
| 629 | |
| 630 | <I>Reserved words</I> are words that have a special meaning to the shell. |
| 631 | The following words are recognized as reserved when unquoted and either |
| 632 | the first word of a simple command (see |
| 633 | <FONT SIZE=-1><B>SHELL GRAMMAR</B> |
| 634 | |
| 635 | </FONT> |
| 636 | below) or the third word of a |
| 637 | <B>case </B> |
| 638 | |
| 639 | or |
| 640 | <B>for</B> |
| 641 | |
| 642 | command: |
| 643 | <DL COMPACT><DT><DD> |
| 644 | |
| 645 | <P> |
| 646 | |
| 647 | <B> |
| 648 | </B> |
| 649 | |
| 650 | ! case do done elif else esac fi for function if in select then until while { } time [[ ]] |
| 651 | </DL> |
| 652 | |
| 653 | |
| 654 | <A NAME="lbAK"> </A> |
| 655 | <H3>SHELL GRAMMAR</H3> |
| 656 | |
| 657 | <A NAME="lbAL"> </A> |
| 658 | <H4>Simple Commands</H4> |
| 659 | |
| 660 | <P> |
| 661 | |
| 662 | A <I>simple command</I> is a sequence of optional variable assignments |
| 663 | followed by <B>blank</B>-separated words and redirections, and |
| 664 | terminated by a <I>control operator</I>. The first word |
| 665 | specifies the command to be executed, and is passed as argument zero. |
| 666 | The remaining words are passed as arguments to the invoked command. |
| 667 | <P> |
| 668 | |
| 669 | The return value of a <I>simple command</I> is its exit status, or |
| 670 | 128+<I>n</I> if the command is terminated by signal |
| 671 | <I>n</I>. |
| 672 | |
| 673 | <A NAME="lbAM"> </A> |
| 674 | <H4>Pipelines</H4> |
| 675 | |
| 676 | <P> |
| 677 | |
| 678 | A <I>pipeline</I> is a sequence of one or more commands separated by |
| 679 | one of the control operators |
| 680 | <B>|</B> |
| 681 | |
| 682 | or <B>|&</B>. |
| 683 | The format for a pipeline is: |
| 684 | <DL COMPACT><DT><DD> |
| 685 | <P> |
| 686 | |
| 687 | [<B>time</B> [<B>-p</B>]] [ ! ] <I>command</I> [ [<B>|</B>|<B>|&</B>] <I>command2</I> ... ] |
| 688 | </DL> |
| 689 | |
| 690 | <P> |
| 691 | |
| 692 | The standard output of |
| 693 | <I>command</I> |
| 694 | |
| 695 | is connected via a pipe to the standard input of |
| 696 | <I>command2</I>. |
| 697 | |
| 698 | This connection is performed before any redirections specified by the |
| 699 | command (see |
| 700 | <FONT SIZE=-1><B>REDIRECTION</B> |
| 701 | |
| 702 | </FONT> |
| 703 | below). |
| 704 | If <B>|&</B> is used, the standard error of <I>command</I> is connected to |
| 705 | <I>command2</I>'s standard input through the pipe; it is shorthand for |
| 706 | <B>2>&1 |</B>. |
| 707 | This implicit redirection of the standard error is performed after any |
| 708 | redirections specified by the command. |
| 709 | <P> |
| 710 | |
| 711 | The return status of a pipeline is the exit status of the last |
| 712 | command, unless the <B>pipefail</B> option is enabled. |
| 713 | If <B>pipefail</B> is enabled, the pipeline's return status is the |
| 714 | value of the last (rightmost) command to exit with a non-zero status, |
| 715 | or zero if all commands exit successfully. |
| 716 | If the reserved word |
| 717 | <B>!</B> |
| 718 | |
| 719 | precedes a pipeline, the exit status of that pipeline is the logical |
| 720 | negation of the exit status as described above. |
| 721 | The shell waits for all commands in the pipeline to |
| 722 | terminate before returning a value. |
| 723 | <P> |
| 724 | |
| 725 | If the |
| 726 | <B>time</B> |
| 727 | |
| 728 | reserved word precedes a pipeline, the elapsed as well as user and |
| 729 | system time consumed by its execution are reported when the pipeline |
| 730 | terminates. |
| 731 | The <B>-p</B> option changes the output format to that specified by POSIX. |
| 732 | The |
| 733 | <FONT SIZE=-1><B>TIMEFORMAT</B> |
| 734 | |
| 735 | </FONT> |
| 736 | variable may be set to a format string that specifies how the timing |
| 737 | information should be displayed; see the description of |
| 738 | <FONT SIZE=-1><B>TIMEFORMAT</B> |
| 739 | |
| 740 | </FONT> |
| 741 | under |
| 742 | <B>Shell Variables</B> |
| 743 | |
| 744 | below. |
| 745 | <P> |
| 746 | |
| 747 | Each command in a pipeline is executed as a separate process (i.e., in a |
| 748 | subshell). |
| 749 | <A NAME="lbAN"> </A> |
| 750 | <H4>Lists</H4> |
| 751 | |
| 752 | <P> |
| 753 | |
| 754 | A <I>list</I> is a sequence of one or more pipelines separated by one |
| 755 | of the operators |
| 756 | <B>;</B>, |
| 757 | |
| 758 | <B>&</B>, |
| 759 | |
| 760 | <B>&&</B>, |
| 761 | |
| 762 | or |
| 763 | <B>||</B>, |
| 764 | |
| 765 | and optionally terminated by one of |
| 766 | <B>;</B>, |
| 767 | |
| 768 | <B>&</B>, |
| 769 | |
| 770 | or |
| 771 | <B><newline></B>. |
| 772 | |
| 773 | <P> |
| 774 | |
| 775 | Of these list operators, |
| 776 | <B>&&</B> |
| 777 | |
| 778 | and |
| 779 | <B>||</B> |
| 780 | |
| 781 | have equal precedence, followed by |
| 782 | <B>;</B> |
| 783 | |
| 784 | and |
| 785 | <B>&</B>, |
| 786 | |
| 787 | which have equal precedence. |
| 788 | <P> |
| 789 | |
| 790 | A sequence of one or more newlines may appear in a <I>list</I> instead |
| 791 | of a semicolon to delimit commands. |
| 792 | <P> |
| 793 | |
| 794 | If a command is terminated by the control operator |
| 795 | <B>&</B>, |
| 796 | |
| 797 | the shell executes the command in the <I>background</I> |
| 798 | in a subshell. The shell does not wait for the command to |
| 799 | finish, and the return status is 0. Commands separated by a |
| 800 | <B>;</B> |
| 801 | |
| 802 | are executed sequentially; the shell waits for each |
| 803 | command to terminate in turn. The return status is the |
| 804 | exit status of the last command executed. |
| 805 | <P> |
| 806 | |
| 807 | AND and OR lists are sequences of one of more pipelines separated by the |
| 808 | <B>&&</B> and <B>||</B> control operators, respectively. |
| 809 | AND and OR lists are executed with left associativity. |
| 810 | An AND list has the form |
| 811 | <DL COMPACT><DT><DD> |
| 812 | <P> |
| 813 | |
| 814 | <I>command1</I> <B>&&</B> <I>command2</I> |
| 815 | </DL> |
| 816 | |
| 817 | <P> |
| 818 | |
| 819 | <I>command2</I> |
| 820 | |
| 821 | is executed if, and only if, |
| 822 | <I>command1</I> |
| 823 | |
| 824 | returns an exit status of zero. |
| 825 | <P> |
| 826 | |
| 827 | An OR list has the form |
| 828 | <DL COMPACT><DT><DD> |
| 829 | <P> |
| 830 | |
| 831 | <I>command1</I> <B>||</B> <I>command2</I> |
| 832 | <P> |
| 833 | |
| 834 | </DL> |
| 835 | |
| 836 | <P> |
| 837 | |
| 838 | <I>command2</I> |
| 839 | |
| 840 | is executed if and only if |
| 841 | <I>command1</I> |
| 842 | |
| 843 | returns a non-zero exit status. |
| 844 | The return status of |
| 845 | AND and OR lists is the exit status of the last command |
| 846 | executed in the list. |
| 847 | <A NAME="lbAO"> </A> |
| 848 | <H4>Compound Commands</H4> |
| 849 | |
| 850 | <P> |
| 851 | |
| 852 | A <I>compound command</I> is one of the following: |
| 853 | <DL COMPACT> |
| 854 | <DT>(<I>list</I>)<DD> |
| 855 | <I>list</I> is executed in a subshell environment (see |
| 856 | <FONT SIZE=-1><B>COMMAND EXECUTION ENVIRONMENT</B></FONT> |
| 857 | below). |
| 858 | Variable assignments and builtin |
| 859 | commands that affect the shell's environment do not remain in effect |
| 860 | after the command completes. The return status is the exit status of |
| 861 | <I>list</I>. |
| 862 | <DT>{ <I>list</I>; }<DD> |
| 863 | <I>list</I> is simply executed in the current shell environment. |
| 864 | <I>list</I> must be terminated with a newline or semicolon. |
| 865 | This is known as a <I>group command</I>. |
| 866 | The return status is the exit status of |
| 867 | <I>list</I>. |
| 868 | Note that unlike the metacharacters <B>(</B> and <B>)</B>, <B>{</B> and |
| 869 | <B>}</B> are <I>reserved words</I> and must occur where a reserved |
| 870 | word is permitted to be recognized. Since they do not cause a word |
| 871 | break, they must be separated from <I>list</I> by whitespace or another |
| 872 | shell metacharacter. |
| 873 | <DT>((<I>expression</I>))<DD> |
| 874 | The <I>expression</I> is evaluated according to the rules described |
| 875 | below under |
| 876 | <FONT SIZE=-1><B>ARITHMETIC EVALUATION</B>. |
| 877 | |
| 878 | </FONT> |
| 879 | If the value of the expression is non-zero, the return status is 0; |
| 880 | otherwise the return status is 1. This is exactly equivalent to |
| 881 | <B>let "</B><I>expression</I>". |
| 882 | <DT><B>[[</B> <I>expression</I> <B>]]</B><DD> |
| 883 | Return a status of 0 or 1 depending on the evaluation of |
| 884 | the conditional expression <I>expression</I>. |
| 885 | Expressions are composed of the primaries described below under |
| 886 | <FONT SIZE=-1><B>CONDITIONAL EXPRESSIONS</B>. |
| 887 | |
| 888 | </FONT> |
| 889 | Word splitting and pathname expansion are not performed on the words |
| 890 | between the <B>[[</B> and <B>]]</B>; tilde expansion, parameter and |
| 891 | variable expansion, arithmetic expansion, command substitution, process |
| 892 | substitution, and quote removal are performed. |
| 893 | Conditional operators such as <B>-f</B> must be unquoted to be recognized |
| 894 | as primaries. |
| 895 | <P> |
| 896 | |
| 897 | |
| 898 | When the <B>==</B> and <B>!=</B> operators are used, the string to the |
| 899 | right of the operator is considered a pattern and matched according |
| 900 | to the rules described below under <B>Pattern Matching</B>. |
| 901 | If the shell option |
| 902 | <B>nocasematch</B> |
| 903 | |
| 904 | is enabled, the match is performed without regard to the case |
| 905 | of alphabetic characters. |
| 906 | The return value is 0 if the string matches (<B>==</B>) or does not match |
| 907 | (<B>!=</B>) the pattern, and 1 otherwise. |
| 908 | Any part of the pattern may be quoted to force it to be matched as a |
| 909 | string. |
| 910 | <P> |
| 911 | |
| 912 | |
| 913 | An additional binary operator, <B>=~</B>, is available, with the same |
| 914 | precedence as <B>==</B> and <B>!=</B>. |
| 915 | When it is used, the string to the right of the operator is considered |
| 916 | an extended regular expression and matched accordingly (as in <I>regex</I>(3)). |
| 917 | The return value is 0 if the string matches |
| 918 | the pattern, and 1 otherwise. |
| 919 | If the regular expression is syntactically incorrect, the conditional |
| 920 | expression's return value is 2. |
| 921 | If the shell option |
| 922 | <B>nocasematch</B> |
| 923 | |
| 924 | is enabled, the match is performed without regard to the case |
| 925 | of alphabetic characters. |
| 926 | Any part of the pattern may be quoted to force it to be matched as a |
| 927 | string. |
| 928 | Substrings matched by parenthesized subexpressions within the regular |
| 929 | expression are saved in the array variable <B>BASH_REMATCH</B>. |
| 930 | The element of <B>BASH_REMATCH</B> with index 0 is the portion of the string |
| 931 | matching the entire regular expression. |
| 932 | The element of <B>BASH_REMATCH</B> with index <I>n</I> is the portion of the |
| 933 | string matching the <I>n</I>th parenthesized subexpression. |
| 934 | <P> |
| 935 | |
| 936 | |
| 937 | Expressions may be combined using the following operators, listed |
| 938 | in decreasing order of precedence: |
| 939 | <P> |
| 940 | |
| 941 | |
| 942 | <DL COMPACT><DT><DD> |
| 943 | |
| 944 | <DL COMPACT> |
| 945 | <DT><B>( </B><I>expression</I> ) |
| 946 | |
| 947 | <DD> |
| 948 | Returns the value of <I>expression</I>. |
| 949 | This may be used to override the normal precedence of operators. |
| 950 | <DT><B>! </B><I>expression</I> |
| 951 | |
| 952 | <DD> |
| 953 | True if |
| 954 | <I>expression</I> |
| 955 | |
| 956 | is false. |
| 957 | <DT><I>expression1</I> <B>&&</B> <I>expression2</I><DD> |
| 958 | True if both |
| 959 | <I>expression1</I> |
| 960 | |
| 961 | and |
| 962 | <I>expression2</I> |
| 963 | |
| 964 | are true. |
| 965 | <DT><I>expression1</I> <B>||</B> <I>expression2</I> |
| 966 | <DD> |
| 967 | |
| 968 | True if either |
| 969 | <I>expression1</I> |
| 970 | |
| 971 | or |
| 972 | <I>expression2</I> |
| 973 | |
| 974 | is true. |
| 975 | |
| 976 | </DL> |
| 977 | <P> |
| 978 | |
| 979 | The <B>&&</B> and |
| 980 | <B>||</B> |
| 981 | |
| 982 | operators do not evaluate <I>expression2</I> if the value of |
| 983 | <I>expression1</I> is sufficient to determine the return value of |
| 984 | the entire conditional expression. |
| 985 | </DL> |
| 986 | |
| 987 | <DT><B>for</B> <I>name</I> [ <B>in</B> <I>word</I> ] ; <B>do</B> <I>list</I> ; <B>done</B><DD> |
| 988 | The list of words following <B>in</B> is expanded, generating a list |
| 989 | of items. |
| 990 | The variable <I>name</I> is set to each element of this list |
| 991 | in turn, and <I>list</I> is executed each time. |
| 992 | If the <B>in</B> <I>word</I> is omitted, the <B>for</B> command executes |
| 993 | <I>list</I> once for each positional parameter that is set (see |
| 994 | <FONT SIZE=-1><B>PARAMETERS</B> |
| 995 | |
| 996 | </FONT> |
| 997 | below). |
| 998 | The return status is the exit status of the last command that executes. |
| 999 | If the expansion of the items following <B>in</B> results in an empty |
| 1000 | list, no commands are executed, and the return status is 0. |
| 1001 | <DT><B>for</B> (( <I>expr1</I> ; <I>expr2</I> ; <I>expr3</I> )) ; <B>do</B> <I>list</I> ; <B>done</B><DD> |
| 1002 | First, the arithmetic expression <I>expr1</I> is evaluated according |
| 1003 | to the rules described below under |
| 1004 | <FONT SIZE=-1><B>ARITHMETIC EVALUATION</B>. |
| 1005 | |
| 1006 | </FONT> |
| 1007 | The arithmetic expression <I>expr2</I> is then evaluated repeatedly |
| 1008 | until it evaluates to zero. |
| 1009 | Each time <I>expr2</I> evaluates to a non-zero value, <I>list</I> is |
| 1010 | executed and the arithmetic expression <I>expr3</I> is evaluated. |
| 1011 | If any expression is omitted, it behaves as if it evaluates to 1. |
| 1012 | The return value is the exit status of the last command in <I>list</I> |
| 1013 | that is executed, or false if any of the expressions is invalid. |
| 1014 | <DT><B>select</B> <I>name</I> [ <B>in</B> <I>word</I> ] ; <B>do</B> <I>list</I> ; <B>done</B><DD> |
| 1015 | The list of words following <B>in</B> is expanded, generating a list |
| 1016 | of items. The set of expanded words is printed on the standard |
| 1017 | error, each preceded by a number. If the <B>in</B> |
| 1018 | <I>word</I> is omitted, the positional parameters are printed (see |
| 1019 | <FONT SIZE=-1><B>PARAMETERS</B> |
| 1020 | |
| 1021 | </FONT> |
| 1022 | below). The |
| 1023 | <B>PS3</B> |
| 1024 | |
| 1025 | prompt is then displayed and a line read from the standard input. |
| 1026 | If the line consists of a number corresponding to one of |
| 1027 | the displayed words, then the value of |
| 1028 | <I>name</I> |
| 1029 | |
| 1030 | is set to that word. If the line is empty, the words and prompt |
| 1031 | are displayed again. If EOF is read, the command completes. Any |
| 1032 | other value read causes |
| 1033 | <I>name</I> |
| 1034 | |
| 1035 | to be set to null. The line read is saved in the variable |
| 1036 | <B>REPLY</B>. |
| 1037 | |
| 1038 | The |
| 1039 | <I>list</I> |
| 1040 | |
| 1041 | is executed after each selection until a |
| 1042 | <B>break</B> |
| 1043 | |
| 1044 | command is executed. |
| 1045 | The exit status of |
| 1046 | <B>select</B> |
| 1047 | |
| 1048 | is the exit status of the last command executed in |
| 1049 | <I>list</I>, |
| 1050 | |
| 1051 | or zero if no commands were executed. |
| 1052 | <DT><B>case</B> <I>word</I> <B>in</B> [ [(] <I>pattern</I> [ <B>|</B> <I>pattern</I> ] |
| 1053 | <DD> |
| 1054 | A <B>case</B> command first expands <I>word</I>, and tries to match |
| 1055 | it against each <I>pattern</I> in turn, using the same matching rules |
| 1056 | as for pathname expansion (see |
| 1057 | <B>Pathname Expansion</B> |
| 1058 | |
| 1059 | below). |
| 1060 | The <I>word</I> is expanded using tilde |
| 1061 | expansion, parameter and variable expansion, arithmetic substitution, |
| 1062 | command substitution, process substitution and quote removal. |
| 1063 | Each <I>pattern</I> examined is expanded using tilde |
| 1064 | expansion, parameter and variable expansion, arithmetic substitution, |
| 1065 | command substitution, and process substitution. |
| 1066 | If the shell option |
| 1067 | <B>nocasematch</B> |
| 1068 | |
| 1069 | is enabled, the match is performed without regard to the case |
| 1070 | of alphabetic characters. |
| 1071 | When a match is found, the corresponding <I>list</I> is executed. |
| 1072 | If the <B>;;</B> operator is used, no subsequent matches are attempted after |
| 1073 | the first pattern match. |
| 1074 | Using <B>;&</B> in place of <B>;;</B> causes execution to continue with |
| 1075 | the <I>list</I> associated with the next set of patterns. |
| 1076 | Using <B>;;&</B> in place of <B>;;</B> causes the shell to test the next |
| 1077 | pattern list in the statement, if any, and execute any associated <I>list</I> |
| 1078 | on a successful match. |
| 1079 | The exit status is zero if no |
| 1080 | pattern matches. Otherwise, it is the exit status of the |
| 1081 | last command executed in <I>list</I>. |
| 1082 | <DT><B>if</B> <I>list</I>; <B>then</B> <I>list;</I> [ <B>elif</B> <I>list</I>; <B>then</B> <I>list</I>; ] ... [ <B>else</B> <I>list</I>; ] <B>fi</B><DD> |
| 1083 | The |
| 1084 | <B>if </B> |
| 1085 | |
| 1086 | <I>list</I> |
| 1087 | |
| 1088 | is executed. If its exit status is zero, the |
| 1089 | <B>then</B> <I>list</I> is executed. Otherwise, each <B>elif</B> |
| 1090 | <I>list</I> is executed in turn, and if its exit status is zero, |
| 1091 | the corresponding <B>then</B> <I>list</I> is executed and the |
| 1092 | command completes. Otherwise, the <B>else</B> <I>list</I> is |
| 1093 | executed, if present. The exit status is the exit status of the |
| 1094 | last command executed, or zero if no condition tested true. |
| 1095 | <DT><B>while</B> <I>list</I>; <B>do</B> <I>list</I>; <B>done</B><DD> |
| 1096 | |
| 1097 | <DT><B>until</B> <I>list</I>; <B>do</B> <I>list</I>; <B>done</B><DD> |
| 1098 | |
| 1099 | The <B>while</B> command continuously executes the <B>do</B> |
| 1100 | <I>list</I> as long as the last command in <I>list</I> returns |
| 1101 | an exit status of zero. The <B>until</B> command is identical |
| 1102 | to the <B>while</B> command, except that the test is negated; |
| 1103 | the |
| 1104 | <B>do</B> |
| 1105 | |
| 1106 | <I>list</I> |
| 1107 | |
| 1108 | is executed as long as the last command in |
| 1109 | <I>list</I> |
| 1110 | |
| 1111 | returns a non-zero exit status. |
| 1112 | The exit status of the <B>while</B> and <B>until</B> commands |
| 1113 | is the exit status |
| 1114 | of the last <B>do</B> <I>list</I> command executed, or zero if |
| 1115 | none was executed. |
| 1116 | </DL> |
| 1117 | <A NAME="lbAP"> </A> |
| 1118 | <H4>Coprocesses</H4> |
| 1119 | |
| 1120 | <P> |
| 1121 | |
| 1122 | A <I>coprocess</I> is a shell command preceded by the <B>coproc</B> reserved |
| 1123 | word. |
| 1124 | A coprocess is executed asynchronously in a subshell, as if the command |
| 1125 | had been terminated with the <B>&</B> control operator, with a two-way pipe |
| 1126 | established between the executing shell and the coprocess. |
| 1127 | <P> |
| 1128 | |
| 1129 | The format for a coprocess is: |
| 1130 | <DL COMPACT><DT><DD> |
| 1131 | <P> |
| 1132 | |
| 1133 | <B>coproc</B> [<I>NAME</I>] <I>command</I> [<I>redirections</I>] |
| 1134 | </DL> |
| 1135 | |
| 1136 | <P> |
| 1137 | |
| 1138 | This creates a coprocess named <I>NAME</I>. |
| 1139 | If <I>NAME</I> is not supplied, the default name is <I>COPROC</I>. |
| 1140 | <I>NAME</I> must not be supplied if <I>command</I> is a <I>simple |
| 1141 | command</I> (see above); otherwise, it is interpreted as the first word |
| 1142 | of the simple command. |
| 1143 | When the coproc is executed, the shell creates an array variable (see |
| 1144 | <B>Arrays</B> |
| 1145 | |
| 1146 | below) named <I>NAME</I> in the context of the executing shell. |
| 1147 | The standard output of |
| 1148 | <I>command</I> |
| 1149 | |
| 1150 | is connected via a pipe to a file descriptor in the executing shell, |
| 1151 | and that file descriptor is assigned to <I>NAME</I>[0]. |
| 1152 | The standard input of |
| 1153 | <I>command</I> |
| 1154 | |
| 1155 | is connected via a pipe to a file descriptor in the executing shell, |
| 1156 | and that file descriptor is assigned to <I>NAME</I>[1]. |
| 1157 | This pipe is established before any redirections specified by the |
| 1158 | command (see |
| 1159 | <FONT SIZE=-1><B>REDIRECTION</B> |
| 1160 | |
| 1161 | </FONT> |
| 1162 | below). |
| 1163 | The file descriptors can be utilized as arguments to shell commands |
| 1164 | and redirections using standard word expansions. |
| 1165 | The process id of the shell spawned to execute the coprocess is |
| 1166 | available as the value of the variable <I>NAME</I>_PID. |
| 1167 | The <B>wait</B> |
| 1168 | builtin command may be used to wait for the coprocess to terminate. |
| 1169 | <P> |
| 1170 | |
| 1171 | The return status of a coprocess is the exit status of <I>command</I>. |
| 1172 | <A NAME="lbAQ"> </A> |
| 1173 | <H4>Shell Function Definitions</H4> |
| 1174 | |
| 1175 | <P> |
| 1176 | |
| 1177 | A shell function is an object that is called like a simple command and |
| 1178 | executes a compound command with a new set of positional parameters. |
| 1179 | Shell functions are declared as follows: |
| 1180 | <DL COMPACT> |
| 1181 | <DT>[ <B>function</B> ] <I>name</I> () <I>compound-command</I> [<I>redirection</I>]<DD> |
| 1182 | This defines a function named <I>name</I>. |
| 1183 | The reserved word <B>function</B> is optional. |
| 1184 | If the <B>function</B> reserved word is supplied, the parentheses are optional. |
| 1185 | The <I>body</I> of the function is the compound command |
| 1186 | <I>compound-command </I> |
| 1187 | |
| 1188 | (see <B>Compound Commands</B> above). |
| 1189 | That command is usually a <I>list</I> of commands between { and }, but |
| 1190 | may be any command listed under <B>Compound Commands</B> above. |
| 1191 | <I>compound-command</I> is executed whenever <I>name</I> is specified as the |
| 1192 | name of a simple command. |
| 1193 | Any redirections (see |
| 1194 | <FONT SIZE=-1><B>REDIRECTION</B> |
| 1195 | |
| 1196 | </FONT> |
| 1197 | below) specified when a function is defined are performed |
| 1198 | when the function is executed. |
| 1199 | The exit status of a function definition is zero unless a syntax error |
| 1200 | occurs or a readonly function with the same name already exists. |
| 1201 | When executed, the exit status of a function is the exit status of the |
| 1202 | last command executed in the body. (See |
| 1203 | <FONT SIZE=-1><B>FUNCTIONS</B> |
| 1204 | |
| 1205 | </FONT> |
| 1206 | below.) |
| 1207 | </DL> |
| 1208 | <A NAME="lbAR"> </A> |
| 1209 | <H3>COMMENTS</H3> |
| 1210 | |
| 1211 | In a non-interactive shell, or an interactive shell in which the |
| 1212 | <B>interactive_comments</B> |
| 1213 | |
| 1214 | option to the |
| 1215 | <B>shopt</B> |
| 1216 | |
| 1217 | builtin is enabled (see |
| 1218 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 1219 | |
| 1220 | </FONT> |
| 1221 | below), a word beginning with |
| 1222 | <B>#</B> |
| 1223 | |
| 1224 | causes that word and all remaining characters on that line to |
| 1225 | be ignored. An interactive shell without the |
| 1226 | <B>interactive_comments</B> |
| 1227 | |
| 1228 | option enabled does not allow comments. The |
| 1229 | <B>interactive_comments</B> |
| 1230 | |
| 1231 | option is on by default in interactive shells. |
| 1232 | <A NAME="lbAS"> </A> |
| 1233 | <H3>QUOTING</H3> |
| 1234 | |
| 1235 | <I>Quoting</I> is used to remove the special meaning of certain |
| 1236 | characters or words to the shell. Quoting can be used to |
| 1237 | disable special treatment for special characters, to prevent |
| 1238 | reserved words from being recognized as such, and to prevent |
| 1239 | parameter expansion. |
| 1240 | <P> |
| 1241 | |
| 1242 | Each of the <I>metacharacters</I> listed above under |
| 1243 | <FONT SIZE=-1><B>DEFINITIONS</B> |
| 1244 | |
| 1245 | </FONT> |
| 1246 | has special meaning to the shell and must be quoted if it is to |
| 1247 | represent itself. |
| 1248 | <P> |
| 1249 | |
| 1250 | When the command history expansion facilities are being used |
| 1251 | (see |
| 1252 | <FONT SIZE=-1><B>HISTORY EXPANSION</B> |
| 1253 | |
| 1254 | </FONT> |
| 1255 | below), the |
| 1256 | <I>history expansion</I> character, usually <B>!</B>, must be quoted |
| 1257 | to prevent history expansion. |
| 1258 | <P> |
| 1259 | |
| 1260 | There are three quoting mechanisms: the |
| 1261 | <I>escape character</I>, |
| 1262 | |
| 1263 | single quotes, and double quotes. |
| 1264 | <P> |
| 1265 | |
| 1266 | A non-quoted backslash (<B>\</B>) is the |
| 1267 | <I>escape character</I>. |
| 1268 | |
| 1269 | It preserves the literal value of the next character that follows, |
| 1270 | with the exception of <newline>. If a <B>\</B><newline> pair |
| 1271 | appears, and the backslash is not itself quoted, the <B>\</B><newline> |
| 1272 | is treated as a line continuation (that is, it is removed from the |
| 1273 | input stream and effectively ignored). |
| 1274 | <P> |
| 1275 | |
| 1276 | Enclosing characters in single quotes preserves the literal value |
| 1277 | of each character within the quotes. A single quote may not occur |
| 1278 | between single quotes, even when preceded by a backslash. |
| 1279 | <P> |
| 1280 | |
| 1281 | Enclosing characters in double quotes preserves the literal value |
| 1282 | of all characters within the quotes, with the exception of |
| 1283 | <B>$</B>, |
| 1284 | |
| 1285 | <B>`</B>, |
| 1286 | |
| 1287 | <B>\</B>, |
| 1288 | |
| 1289 | and, when history expansion is enabled, |
| 1290 | <B>!</B>. |
| 1291 | |
| 1292 | The characters |
| 1293 | <B>$</B> |
| 1294 | |
| 1295 | and |
| 1296 | <B>`</B> |
| 1297 | |
| 1298 | retain their special meaning within double quotes. The backslash |
| 1299 | retains its special meaning only when followed by one of the following |
| 1300 | characters: |
| 1301 | <B>$</B>, |
| 1302 | |
| 1303 | <B>`</B>, |
| 1304 | |
| 1305 | <B>"</B>, |
| 1306 | <B>\</B>, |
| 1307 | |
| 1308 | or |
| 1309 | <B><newline></B>. |
| 1310 | |
| 1311 | A double quote may be quoted within double quotes by preceding it with |
| 1312 | a backslash. |
| 1313 | If enabled, history expansion will be performed unless an |
| 1314 | <B>!</B> |
| 1315 | |
| 1316 | appearing in double quotes is escaped using a backslash. |
| 1317 | The backslash preceding the |
| 1318 | <B>!</B> |
| 1319 | |
| 1320 | is not removed. |
| 1321 | <P> |
| 1322 | |
| 1323 | The special parameters |
| 1324 | <B>*</B> |
| 1325 | |
| 1326 | and |
| 1327 | <B>@</B> |
| 1328 | |
| 1329 | have special meaning when in double |
| 1330 | quotes (see |
| 1331 | <FONT SIZE=-1><B>PARAMETERS</B> |
| 1332 | |
| 1333 | </FONT> |
| 1334 | below). |
| 1335 | <P> |
| 1336 | |
| 1337 | Words of the form <B>$</B>aq<I>string</I>aq are treated specially. The |
| 1338 | word expands to <I>string</I>, with backslash-escaped characters replaced |
| 1339 | as specified by the ANSI C standard. Backslash escape sequences, if |
| 1340 | present, are decoded as follows: |
| 1341 | <DL COMPACT><DT><DD> |
| 1342 | |
| 1343 | <DL COMPACT> |
| 1344 | <DT><B>\a</B> |
| 1345 | |
| 1346 | <DD> |
| 1347 | alert (bell) |
| 1348 | <DT><B>\b</B> |
| 1349 | |
| 1350 | <DD> |
| 1351 | backspace |
| 1352 | <DT><B>\e</B> |
| 1353 | |
| 1354 | <DD> |
| 1355 | an escape character |
| 1356 | <DT><B>\f</B> |
| 1357 | |
| 1358 | <DD> |
| 1359 | form feed |
| 1360 | <DT><B>\n</B> |
| 1361 | |
| 1362 | <DD> |
| 1363 | new line |
| 1364 | <DT><B>\r</B> |
| 1365 | |
| 1366 | <DD> |
| 1367 | carriage return |
| 1368 | <DT><B>\t</B> |
| 1369 | |
| 1370 | <DD> |
| 1371 | horizontal tab |
| 1372 | <DT><B>\v</B> |
| 1373 | |
| 1374 | <DD> |
| 1375 | vertical tab |
| 1376 | <DT><B>\\</B> |
| 1377 | |
| 1378 | <DD> |
| 1379 | backslash |
| 1380 | <DT><B>\aq</B> |
| 1381 | |
| 1382 | <DD> |
| 1383 | single quote |
| 1384 | <DT><B>\</B><I>nnn</I> |
| 1385 | |
| 1386 | <DD> |
| 1387 | the eight-bit character whose value is the octal value <I>nnn</I> |
| 1388 | (one to three digits) |
| 1389 | <DT><B>\x</B><I>HH</I> |
| 1390 | |
| 1391 | <DD> |
| 1392 | the eight-bit character whose value is the hexadecimal value <I>HH</I> |
| 1393 | (one or two hex digits) |
| 1394 | <DT><B>\c</B><I>x</I> |
| 1395 | |
| 1396 | <DD> |
| 1397 | a control-<I>x</I> character |
| 1398 | |
| 1399 | </DL></DL> |
| 1400 | |
| 1401 | <P> |
| 1402 | |
| 1403 | The expanded result is single-quoted, as if the dollar sign had |
| 1404 | not been present. |
| 1405 | <P> |
| 1406 | |
| 1407 | A double-quoted string preceded by a dollar sign (<B>$</B>) will cause |
| 1408 | the string to be translated according to the current locale. |
| 1409 | If the current locale is <B>C</B> or <B>POSIX</B>, the dollar sign |
| 1410 | is ignored. |
| 1411 | If the string is translated and replaced, the replacement is |
| 1412 | double-quoted. |
| 1413 | <A NAME="lbAT"> </A> |
| 1414 | <H3>PARAMETERS</H3> |
| 1415 | |
| 1416 | A |
| 1417 | <I>parameter</I> |
| 1418 | |
| 1419 | is an entity that stores values. |
| 1420 | It can be a |
| 1421 | <I>name</I>, |
| 1422 | |
| 1423 | a number, or one of the special characters listed below under |
| 1424 | <B>Special Parameters</B>. |
| 1425 | |
| 1426 | A |
| 1427 | <I>variable</I> |
| 1428 | |
| 1429 | is a parameter denoted by a |
| 1430 | <I>name</I>. |
| 1431 | |
| 1432 | A variable has a <I>value</I> and zero or more <I>attributes</I>. |
| 1433 | Attributes are assigned using the |
| 1434 | <B>declare</B> |
| 1435 | |
| 1436 | builtin command (see |
| 1437 | <B>declare</B> |
| 1438 | |
| 1439 | below in |
| 1440 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>). |
| 1441 | |
| 1442 | </FONT> |
| 1443 | <P> |
| 1444 | |
| 1445 | A parameter is set if it has been assigned a value. The null string is |
| 1446 | a valid value. Once a variable is set, it may be unset only by using |
| 1447 | the |
| 1448 | <B>unset</B> |
| 1449 | |
| 1450 | builtin command (see |
| 1451 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 1452 | |
| 1453 | </FONT> |
| 1454 | below). |
| 1455 | <P> |
| 1456 | |
| 1457 | A |
| 1458 | <I>variable</I> |
| 1459 | |
| 1460 | may be assigned to by a statement of the form |
| 1461 | <DL COMPACT><DT><DD> |
| 1462 | <P> |
| 1463 | |
| 1464 | <I>name</I>=[<I>value</I>] |
| 1465 | </DL> |
| 1466 | |
| 1467 | <P> |
| 1468 | |
| 1469 | If |
| 1470 | <I>value</I> |
| 1471 | |
| 1472 | is not given, the variable is assigned the null string. All |
| 1473 | <I>values</I> |
| 1474 | |
| 1475 | undergo tilde expansion, parameter and variable expansion, |
| 1476 | command substitution, arithmetic expansion, and quote |
| 1477 | removal (see |
| 1478 | <FONT SIZE=-1><B>EXPANSION</B> |
| 1479 | |
| 1480 | </FONT> |
| 1481 | below). If the variable has its |
| 1482 | <B>integer</B> |
| 1483 | |
| 1484 | attribute set, then |
| 1485 | <I>value</I> |
| 1486 | |
| 1487 | is evaluated as an arithmetic expression even if the $((...)) expansion is |
| 1488 | not used (see |
| 1489 | <B>Arithmetic Expansion</B> |
| 1490 | |
| 1491 | below). |
| 1492 | Word splitting is not performed, with the exception |
| 1493 | of <B>"$@"</B> as explained below under |
| 1494 | <B>Special Parameters</B>. |
| 1495 | |
| 1496 | Pathname expansion is not performed. |
| 1497 | Assignment statements may also appear as arguments to the |
| 1498 | <B>alias</B>, |
| 1499 | |
| 1500 | <B>declare</B>, |
| 1501 | |
| 1502 | <B>typeset</B>, |
| 1503 | |
| 1504 | <B>export</B>, |
| 1505 | |
| 1506 | <B>readonly</B>, |
| 1507 | |
| 1508 | and |
| 1509 | <B>local</B> |
| 1510 | |
| 1511 | builtin commands. |
| 1512 | <P> |
| 1513 | |
| 1514 | In the context where an assignment statement is assigning a value |
| 1515 | to a shell variable or array index, the += operator can be used to |
| 1516 | append to or add to the variable's previous value. |
| 1517 | When += is applied to a variable for which the integer attribute has been |
| 1518 | set, <I>value</I> is evaluated as an arithmetic expression and added to the |
| 1519 | variable's current value, which is also evaluated. |
| 1520 | When += is applied to an array variable using compound assignment (see |
| 1521 | <B>Arrays</B> |
| 1522 | |
| 1523 | below), the |
| 1524 | variable's value is not unset (as it is when using =), and new values are |
| 1525 | appended to the array beginning at one greater than the array's maximum index |
| 1526 | (for indexed arrays) or added as additional key-value pairs in an |
| 1527 | associative array. |
| 1528 | When applied to a string-valued variable, <I>value</I> is expanded and |
| 1529 | appended to the variable's value. |
| 1530 | <A NAME="lbAU"> </A> |
| 1531 | <H4>Positional Parameters</H4> |
| 1532 | |
| 1533 | <P> |
| 1534 | |
| 1535 | A |
| 1536 | <I>positional parameter</I> |
| 1537 | |
| 1538 | is a parameter denoted by one or more |
| 1539 | digits, other than the single digit 0. Positional parameters are |
| 1540 | assigned from the shell's arguments when it is invoked, |
| 1541 | and may be reassigned using the |
| 1542 | <B>set</B> |
| 1543 | |
| 1544 | builtin command. Positional parameters may not be assigned to |
| 1545 | with assignment statements. The positional parameters are |
| 1546 | temporarily replaced when a shell function is executed (see |
| 1547 | <FONT SIZE=-1><B>FUNCTIONS</B> |
| 1548 | |
| 1549 | </FONT> |
| 1550 | below). |
| 1551 | <P> |
| 1552 | |
| 1553 | When a positional parameter consisting of more than a single |
| 1554 | digit is expanded, it must be enclosed in braces (see |
| 1555 | <FONT SIZE=-1><B>EXPANSION</B> |
| 1556 | |
| 1557 | </FONT> |
| 1558 | below). |
| 1559 | <A NAME="lbAV"> </A> |
| 1560 | <H4>Special Parameters</H4> |
| 1561 | |
| 1562 | <P> |
| 1563 | |
| 1564 | The shell treats several parameters specially. These parameters may |
| 1565 | only be referenced; assignment to them is not allowed. |
| 1566 | |
| 1567 | <DL COMPACT> |
| 1568 | <DT><B>*</B> |
| 1569 | |
| 1570 | <DD> |
| 1571 | Expands to the positional parameters, starting from one. When the |
| 1572 | expansion occurs within double quotes, it expands to a single word |
| 1573 | with the value of each parameter separated by the first character |
| 1574 | of the |
| 1575 | <FONT SIZE=-1><B>IFS</B> |
| 1576 | |
| 1577 | </FONT> |
| 1578 | special variable. That is, "<B>$*</B>" is equivalent |
| 1579 | to "<B>$1</B><I>c</I><B>$2</B><I>c</I><B>...</B>", where |
| 1580 | <I>c</I> |
| 1581 | |
| 1582 | is the first character of the value of the |
| 1583 | <FONT SIZE=-1><B>IFS</B> |
| 1584 | |
| 1585 | </FONT> |
| 1586 | variable. If |
| 1587 | <FONT SIZE=-1><B>IFS</B> |
| 1588 | |
| 1589 | </FONT> |
| 1590 | is unset, the parameters are separated by spaces. |
| 1591 | If |
| 1592 | <FONT SIZE=-1><B>IFS</B> |
| 1593 | |
| 1594 | </FONT> |
| 1595 | is null, the parameters are joined without intervening separators. |
| 1596 | <DT><B>@</B> |
| 1597 | |
| 1598 | <DD> |
| 1599 | Expands to the positional parameters, starting from one. When the |
| 1600 | expansion occurs within double quotes, each parameter expands to a |
| 1601 | separate word. That is, "<B>$@</B>" is equivalent to |
| 1602 | "<B>$1</B>" "<B>$2</B>" ... |
| 1603 | If the double-quoted expansion occurs within a word, the expansion of |
| 1604 | the first parameter is joined with the beginning part of the original |
| 1605 | word, and the expansion of the last parameter is joined with the last |
| 1606 | part of the original word. |
| 1607 | When there are no positional parameters, "<B>$@</B>" and |
| 1608 | <B>$@</B> |
| 1609 | |
| 1610 | expand to nothing (i.e., they are removed). |
| 1611 | <DT><B>#</B> |
| 1612 | |
| 1613 | <DD> |
| 1614 | Expands to the number of positional parameters in decimal. |
| 1615 | <DT><B>?</B> |
| 1616 | |
| 1617 | <DD> |
| 1618 | Expands to the exit status of the most recently executed foreground |
| 1619 | pipeline. |
| 1620 | <DT><B>-</B> |
| 1621 | |
| 1622 | <DD> |
| 1623 | Expands to the current option flags as specified upon invocation, |
| 1624 | by the |
| 1625 | <B>set</B> |
| 1626 | |
| 1627 | builtin command, or those set by the shell itself |
| 1628 | (such as the |
| 1629 | <B>-i</B> |
| 1630 | |
| 1631 | option). |
| 1632 | <DT><B>$</B> |
| 1633 | |
| 1634 | <DD> |
| 1635 | Expands to the process ID of the shell. In a () subshell, it |
| 1636 | expands to the process ID of the current shell, not the |
| 1637 | subshell. |
| 1638 | <DT><B>!</B> |
| 1639 | |
| 1640 | <DD> |
| 1641 | Expands to the process ID of the most recently executed background |
| 1642 | (asynchronous) command. |
| 1643 | <DT><B>0</B> |
| 1644 | |
| 1645 | <DD> |
| 1646 | Expands to the name of the shell or shell script. This is set at |
| 1647 | shell initialization. If |
| 1648 | <B>bash</B> |
| 1649 | |
| 1650 | is invoked with a file of commands, |
| 1651 | <B>$0</B> |
| 1652 | |
| 1653 | is set to the name of that file. If |
| 1654 | <B>bash</B> |
| 1655 | |
| 1656 | is started with the |
| 1657 | <B>-c</B> |
| 1658 | |
| 1659 | option, then |
| 1660 | <B>$0</B> |
| 1661 | |
| 1662 | is set to the first argument after the string to be |
| 1663 | executed, if one is present. Otherwise, it is set |
| 1664 | to the file name used to invoke |
| 1665 | <B>bash</B>, |
| 1666 | |
| 1667 | as given by argument zero. |
| 1668 | <DT><B>_</B> |
| 1669 | |
| 1670 | <DD> |
| 1671 | At shell startup, set to the absolute pathname used to invoke the |
| 1672 | shell or shell script being executed as passed in the environment |
| 1673 | or argument list. |
| 1674 | Subsequently, expands to the last argument to the previous command, |
| 1675 | after expansion. |
| 1676 | Also set to the full pathname used to invoke each command executed |
| 1677 | and placed in the environment exported to that command. |
| 1678 | When checking mail, this parameter holds the name of the mail file |
| 1679 | currently being checked. |
| 1680 | |
| 1681 | </DL> |
| 1682 | <A NAME="lbAW"> </A> |
| 1683 | <H4>Shell Variables</H4> |
| 1684 | |
| 1685 | <P> |
| 1686 | |
| 1687 | The following variables are set by the shell: |
| 1688 | <P> |
| 1689 | |
| 1690 | |
| 1691 | <DL COMPACT> |
| 1692 | <DT><B>BASH</B> |
| 1693 | |
| 1694 | <DD> |
| 1695 | Expands to the full file name used to invoke this instance of |
| 1696 | <B>bash</B>. |
| 1697 | |
| 1698 | <DT><B>BASHPID</B> |
| 1699 | |
| 1700 | <DD> |
| 1701 | Expands to the process id of the current <B>bash</B> process. |
| 1702 | This differs from <B>$$</B> under certain circumstances, such as subshells |
| 1703 | that do not require <B>bash</B> to be re-initialized. |
| 1704 | <DT><B>BASH_ALIASES</B> |
| 1705 | |
| 1706 | <DD> |
| 1707 | An associative array variable whose members correspond to the internal |
| 1708 | list of aliases as maintained by the <B>alias</B> builtin |
| 1709 | Elements added to this array appear in the alias list; unsetting array |
| 1710 | elements cause aliases to be removed from the alias list. |
| 1711 | <DT><B>BASH_ARGC</B> |
| 1712 | |
| 1713 | <DD> |
| 1714 | An array variable whose values are the number of parameters in each |
| 1715 | frame of the current <B>bash</B> execution call stack. |
| 1716 | The number of |
| 1717 | parameters to the current subroutine (shell function or script executed |
| 1718 | with <B>.</B> or <B>source</B>) is at the top of the stack. |
| 1719 | When a subroutine is executed, the number of parameters passed is pushed onto |
| 1720 | <B>BASH_ARGC</B>. |
| 1721 | The shell sets <B>BASH_ARGC</B> only when in extended debugging mode |
| 1722 | (see the description of the |
| 1723 | <B>extdebug</B> |
| 1724 | |
| 1725 | option to the |
| 1726 | <B>shopt</B> |
| 1727 | |
| 1728 | builtin below) |
| 1729 | <DT><B>BASH_ARGV</B> |
| 1730 | |
| 1731 | <DD> |
| 1732 | An array variable containing all of the parameters in the current <B>bash</B> |
| 1733 | execution call stack. The final parameter of the last subroutine call |
| 1734 | is at the top of the stack; the first parameter of the initial call is |
| 1735 | at the bottom. When a subroutine is executed, the parameters supplied |
| 1736 | are pushed onto <B>BASH_ARGV</B>. |
| 1737 | The shell sets <B>BASH_ARGV</B> only when in extended debugging mode |
| 1738 | (see the description of the |
| 1739 | <B>extdebug</B> |
| 1740 | |
| 1741 | option to the |
| 1742 | <B>shopt</B> |
| 1743 | |
| 1744 | builtin below) |
| 1745 | <DT><B>BASH_CMDS</B> |
| 1746 | |
| 1747 | <DD> |
| 1748 | An associative array variable whose members correspond to the internal |
| 1749 | hash table of commands as maintained by the <B>hash</B> builtin. |
| 1750 | Elements added to this array appear in the hash table; unsetting array |
| 1751 | elements cause commands to be removed from the hash table. |
| 1752 | <DT><B>BASH_COMMAND</B> |
| 1753 | |
| 1754 | <DD> |
| 1755 | The command currently being executed or about to be executed, unless the |
| 1756 | shell is executing a command as the result of a trap, |
| 1757 | in which case it is the command executing at the time of the trap. |
| 1758 | <DT><B>BASH_EXECUTION_STRING</B> |
| 1759 | |
| 1760 | <DD> |
| 1761 | The command argument to the <B>-c</B> invocation option. |
| 1762 | <DT><B>BASH_LINENO</B> |
| 1763 | |
| 1764 | <DD> |
| 1765 | An array variable whose members are the line numbers in source files |
| 1766 | corresponding to each member of <B>FUNCNAME</B>. |
| 1767 | <B>${BASH_LINENO[</B><I>$i</I><B>]}</B> is the line number in the source |
| 1768 | file where <B>${FUNCNAME[</B><I>$i</I><B>]}</B> was called |
| 1769 | (or <B>${BASH_LINENO[</B><I>$i-1</I><B>]}</B> if referenced within another |
| 1770 | shell function). |
| 1771 | The corresponding source file name is <B>${BASH_SOURCE[</B><I>$i</I><B>]}. |
| 1772 | Use LINENO</B> to obtain the current line number. |
| 1773 | <DT><B>BASH_REMATCH</B> |
| 1774 | |
| 1775 | <DD> |
| 1776 | An array variable whose members are assigned by the <B>=~</B> binary |
| 1777 | operator to the <B>[[</B> conditional command. |
| 1778 | The element with index 0 is the portion of the string |
| 1779 | matching the entire regular expression. |
| 1780 | The element with index <I>n</I> is the portion of the |
| 1781 | string matching the <I>n</I>th parenthesized subexpression. |
| 1782 | This variable is read-only. |
| 1783 | <DT><B>BASH_SOURCE</B> |
| 1784 | |
| 1785 | <DD> |
| 1786 | An array variable whose members are the source filenames corresponding |
| 1787 | to the elements in the <B>FUNCNAME</B> array variable. |
| 1788 | <DT><B>BASH_SUBSHELL</B> |
| 1789 | |
| 1790 | <DD> |
| 1791 | Incremented by one each time a subshell or subshell environment is spawned. |
| 1792 | The initial value is 0. |
| 1793 | <DT><B>BASH_VERSINFO</B> |
| 1794 | |
| 1795 | <DD> |
| 1796 | A readonly array variable whose members hold version information for |
| 1797 | this instance of |
| 1798 | <B>bash</B>. |
| 1799 | |
| 1800 | The values assigned to the array members are as follows: |
| 1801 | <P> |
| 1802 | <DL COMPACT><DT><DD> |
| 1803 | |
| 1804 | <DL COMPACT> |
| 1805 | <DT><B>BASH_VERSINFO[</B>0] |
| 1806 | |
| 1807 | <DD> |
| 1808 | The major version number (the <I>release</I>). |
| 1809 | <DT><B>BASH_VERSINFO[</B>1] |
| 1810 | |
| 1811 | <DD> |
| 1812 | The minor version number (the <I>version</I>). |
| 1813 | <DT><B>BASH_VERSINFO[</B>2] |
| 1814 | |
| 1815 | <DD> |
| 1816 | The patch level. |
| 1817 | <DT><B>BASH_VERSINFO[</B>3] |
| 1818 | |
| 1819 | <DD> |
| 1820 | The build version. |
| 1821 | <DT><B>BASH_VERSINFO[</B>4] |
| 1822 | |
| 1823 | <DD> |
| 1824 | The release status (e.g., <I>beta1</I>). |
| 1825 | <DT><B>BASH_VERSINFO[</B>5] |
| 1826 | |
| 1827 | <DD> |
| 1828 | The value of <B>MACHTYPE</B>. |
| 1829 | |
| 1830 | </DL></DL> |
| 1831 | |
| 1832 | <DT><B>BASH_VERSION</B> |
| 1833 | |
| 1834 | <DD> |
| 1835 | Expands to a string describing the version of this instance of |
| 1836 | <B>bash</B>. |
| 1837 | |
| 1838 | <DT><B>COMP_CWORD</B> |
| 1839 | |
| 1840 | <DD> |
| 1841 | An index into <B>${COMP_WORDS}</B> of the word containing the current |
| 1842 | cursor position. |
| 1843 | This variable is available only in shell functions invoked by the |
| 1844 | programmable completion facilities (see <B>Programmable Completion</B> |
| 1845 | below). |
| 1846 | <DT><B>COMP_KEY</B> |
| 1847 | |
| 1848 | <DD> |
| 1849 | The key (or final key of a key sequence) used to invoke the current |
| 1850 | completion function. |
| 1851 | <DT><B>COMP_LINE</B> |
| 1852 | |
| 1853 | <DD> |
| 1854 | The current command line. |
| 1855 | This variable is available only in shell functions and external |
| 1856 | commands invoked by the |
| 1857 | programmable completion facilities (see <B>Programmable Completion</B> |
| 1858 | below). |
| 1859 | <DT><B>COMP_POINT</B> |
| 1860 | |
| 1861 | <DD> |
| 1862 | The index of the current cursor position relative to the beginning of |
| 1863 | the current command. |
| 1864 | If the current cursor position is at the end of the current command, |
| 1865 | the value of this variable is equal to <B>${#COMP_LINE}</B>. |
| 1866 | This variable is available only in shell functions and external |
| 1867 | commands invoked by the |
| 1868 | programmable completion facilities (see <B>Programmable Completion</B> |
| 1869 | below). |
| 1870 | <DT><B>COMP_TYPE</B> |
| 1871 | |
| 1872 | <DD> |
| 1873 | Set to an integer value corresponding to the type of completion attempted |
| 1874 | that caused a completion function to be called: |
| 1875 | <I>TAB</I>, for normal completion, |
| 1876 | <I>?</I>, for listing completions after successive tabs, |
| 1877 | <I>!</I>, for listing alternatives on partial word completion, |
| 1878 | <I>@</I>, to list completions if the word is not unmodified, |
| 1879 | or |
| 1880 | <I>%</I>, for menu completion. |
| 1881 | This variable is available only in shell functions and external |
| 1882 | commands invoked by the |
| 1883 | programmable completion facilities (see <B>Programmable Completion</B> |
| 1884 | below). |
| 1885 | <DT><B>COMP_WORDBREAKS</B> |
| 1886 | |
| 1887 | <DD> |
| 1888 | The set of characters that the Readline library treats as word |
| 1889 | separators when performing word completion. |
| 1890 | If |
| 1891 | <FONT SIZE=-1><B>COMP_WORDBREAKS</B> |
| 1892 | |
| 1893 | </FONT> |
| 1894 | is unset, it loses its special properties, even if it is |
| 1895 | subsequently reset. |
| 1896 | <DT><B>COMP_WORDS</B> |
| 1897 | |
| 1898 | <DD> |
| 1899 | An array variable (see <B>Arrays</B> below) consisting of the individual |
| 1900 | words in the current command line. |
| 1901 | The words are split on shell metacharacters as the shell parser would |
| 1902 | separate them. |
| 1903 | This variable is available only in shell functions invoked by the |
| 1904 | programmable completion facilities (see <B>Programmable Completion</B> |
| 1905 | below). |
| 1906 | <DT><B>DIRSTACK</B> |
| 1907 | |
| 1908 | <DD> |
| 1909 | An array variable (see |
| 1910 | <B>Arrays</B> |
| 1911 | |
| 1912 | below) containing the current contents of the directory stack. |
| 1913 | Directories appear in the stack in the order they are displayed by the |
| 1914 | <B>dirs</B> |
| 1915 | |
| 1916 | builtin. |
| 1917 | Assigning to members of this array variable may be used to modify |
| 1918 | directories already in the stack, but the |
| 1919 | <B>pushd</B> |
| 1920 | |
| 1921 | and |
| 1922 | <B>popd</B> |
| 1923 | |
| 1924 | builtins must be used to add and remove directories. |
| 1925 | Assignment to this variable will not change the current directory. |
| 1926 | If |
| 1927 | <FONT SIZE=-1><B>DIRSTACK</B> |
| 1928 | |
| 1929 | </FONT> |
| 1930 | is unset, it loses its special properties, even if it is |
| 1931 | subsequently reset. |
| 1932 | <DT><B>EUID</B> |
| 1933 | |
| 1934 | <DD> |
| 1935 | Expands to the effective user ID of the current user, initialized at |
| 1936 | shell startup. This variable is readonly. |
| 1937 | <DT><B>FUNCNAME</B> |
| 1938 | |
| 1939 | <DD> |
| 1940 | An array variable containing the names of all shell functions |
| 1941 | currently in the execution call stack. |
| 1942 | The element with index 0 is the name of any currently-executing |
| 1943 | shell function. |
| 1944 | The bottom-most element is |
| 1945 | <TT>"main"</TT>. |
| 1946 | |
| 1947 | This variable exists only when a shell function is executing. |
| 1948 | Assignments to |
| 1949 | <FONT SIZE=-1><B>FUNCNAME</B> |
| 1950 | |
| 1951 | </FONT> |
| 1952 | have no effect and return an error status. |
| 1953 | If |
| 1954 | <FONT SIZE=-1><B>FUNCNAME</B> |
| 1955 | |
| 1956 | </FONT> |
| 1957 | is unset, it loses its special properties, even if it is |
| 1958 | subsequently reset. |
| 1959 | <DT><B>GROUPS</B> |
| 1960 | |
| 1961 | <DD> |
| 1962 | An array variable containing the list of groups of which the current |
| 1963 | user is a member. |
| 1964 | Assignments to |
| 1965 | <FONT SIZE=-1><B>GROUPS</B> |
| 1966 | |
| 1967 | </FONT> |
| 1968 | have no effect and return an error status. |
| 1969 | If |
| 1970 | <FONT SIZE=-1><B>GROUPS</B> |
| 1971 | |
| 1972 | </FONT> |
| 1973 | is unset, it loses its special properties, even if it is |
| 1974 | subsequently reset. |
| 1975 | <DT><B>HISTCMD</B> |
| 1976 | |
| 1977 | <DD> |
| 1978 | The history number, or index in the history list, of the current |
| 1979 | command. |
| 1980 | If |
| 1981 | <FONT SIZE=-1><B>HISTCMD</B> |
| 1982 | |
| 1983 | </FONT> |
| 1984 | is unset, it loses its special properties, even if it is |
| 1985 | subsequently reset. |
| 1986 | <DT><B>HOSTNAME</B> |
| 1987 | |
| 1988 | <DD> |
| 1989 | Automatically set to the name of the current host. |
| 1990 | <DT><B>HOSTTYPE</B> |
| 1991 | |
| 1992 | <DD> |
| 1993 | Automatically set to a string that uniquely |
| 1994 | describes the type of machine on which |
| 1995 | <B>bash</B> |
| 1996 | |
| 1997 | is executing. |
| 1998 | The default is system-dependent. |
| 1999 | <DT><B>LINENO</B> |
| 2000 | |
| 2001 | <DD> |
| 2002 | Each time this parameter is referenced, the shell substitutes |
| 2003 | a decimal number representing the current sequential line number |
| 2004 | (starting with 1) within a script or function. When not in a |
| 2005 | script or function, the value substituted is not guaranteed to |
| 2006 | be meaningful. |
| 2007 | If |
| 2008 | <FONT SIZE=-1><B>LINENO</B> |
| 2009 | |
| 2010 | </FONT> |
| 2011 | is unset, it loses its special properties, even if it is |
| 2012 | subsequently reset. |
| 2013 | <DT><B>MACHTYPE</B> |
| 2014 | |
| 2015 | <DD> |
| 2016 | Automatically set to a string that fully describes the system |
| 2017 | type on which |
| 2018 | <B>bash</B> |
| 2019 | |
| 2020 | is executing, in the standard GNU <I>cpu-company-system</I> format. |
| 2021 | The default is system-dependent. |
| 2022 | <DT><B>OLDPWD</B> |
| 2023 | |
| 2024 | <DD> |
| 2025 | The previous working directory as set by the |
| 2026 | <B>cd</B> |
| 2027 | |
| 2028 | command. |
| 2029 | <DT><B>OPTARG</B> |
| 2030 | |
| 2031 | <DD> |
| 2032 | The value of the last option argument processed by the |
| 2033 | <B>getopts</B> |
| 2034 | |
| 2035 | builtin command (see |
| 2036 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 2037 | |
| 2038 | </FONT> |
| 2039 | below). |
| 2040 | <DT><B>OPTIND</B> |
| 2041 | |
| 2042 | <DD> |
| 2043 | The index of the next argument to be processed by the |
| 2044 | <B>getopts</B> |
| 2045 | |
| 2046 | builtin command (see |
| 2047 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 2048 | |
| 2049 | </FONT> |
| 2050 | below). |
| 2051 | <DT><B>OSTYPE</B> |
| 2052 | |
| 2053 | <DD> |
| 2054 | Automatically set to a string that |
| 2055 | describes the operating system on which |
| 2056 | <B>bash</B> |
| 2057 | |
| 2058 | is executing. |
| 2059 | The default is system-dependent. |
| 2060 | <DT><B>PIPESTATUS</B> |
| 2061 | |
| 2062 | <DD> |
| 2063 | An array variable (see |
| 2064 | <B>Arrays</B> |
| 2065 | |
| 2066 | below) containing a list of exit status values from the processes |
| 2067 | in the most-recently-executed foreground pipeline (which may |
| 2068 | contain only a single command). |
| 2069 | <DT><B>PPID</B> |
| 2070 | |
| 2071 | <DD> |
| 2072 | The process ID of the shell's parent. This variable is readonly. |
| 2073 | <DT><B>PWD</B> |
| 2074 | |
| 2075 | <DD> |
| 2076 | The current working directory as set by the |
| 2077 | <B>cd</B> |
| 2078 | |
| 2079 | command. |
| 2080 | <DT><B>RANDOM</B> |
| 2081 | |
| 2082 | <DD> |
| 2083 | Each time this parameter is referenced, a random integer between |
| 2084 | 0 and 32767 is |
| 2085 | generated. The sequence of random numbers may be initialized by assigning |
| 2086 | a value to |
| 2087 | <FONT SIZE=-1><B>RANDOM</B>. |
| 2088 | |
| 2089 | </FONT> |
| 2090 | If |
| 2091 | <FONT SIZE=-1><B>RANDOM</B> |
| 2092 | |
| 2093 | </FONT> |
| 2094 | is unset, it loses its special properties, even if it is |
| 2095 | subsequently reset. |
| 2096 | <DT><B>REPLY</B> |
| 2097 | |
| 2098 | <DD> |
| 2099 | Set to the line of input read by the |
| 2100 | <B>read</B> |
| 2101 | |
| 2102 | builtin command when no arguments are supplied. |
| 2103 | <DT><B>SECONDS</B> |
| 2104 | |
| 2105 | <DD> |
| 2106 | Each time this parameter is |
| 2107 | referenced, the number of seconds since shell invocation is returned. If a |
| 2108 | value is assigned to |
| 2109 | <FONT SIZE=-1><B>SECONDS</B>, |
| 2110 | |
| 2111 | </FONT> |
| 2112 | the value returned upon subsequent |
| 2113 | references is |
| 2114 | the number of seconds since the assignment plus the value assigned. |
| 2115 | If |
| 2116 | <FONT SIZE=-1><B>SECONDS</B> |
| 2117 | |
| 2118 | </FONT> |
| 2119 | is unset, it loses its special properties, even if it is |
| 2120 | subsequently reset. |
| 2121 | <DT><B>SHELLOPTS</B> |
| 2122 | |
| 2123 | <DD> |
| 2124 | A colon-separated list of enabled shell options. Each word in |
| 2125 | the list is a valid argument for the |
| 2126 | <B>-o</B> |
| 2127 | |
| 2128 | option to the |
| 2129 | <B>set</B> |
| 2130 | |
| 2131 | builtin command (see |
| 2132 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 2133 | |
| 2134 | </FONT> |
| 2135 | below). The options appearing in |
| 2136 | <FONT SIZE=-1><B>SHELLOPTS</B> |
| 2137 | |
| 2138 | </FONT> |
| 2139 | are those reported as |
| 2140 | <I>on</I> |
| 2141 | |
| 2142 | by <B>set -o</B>. |
| 2143 | If this variable is in the environment when |
| 2144 | <B>bash</B> |
| 2145 | |
| 2146 | starts up, each shell option in the list will be enabled before |
| 2147 | reading any startup files. |
| 2148 | This variable is read-only. |
| 2149 | <DT><B>SHLVL</B> |
| 2150 | |
| 2151 | <DD> |
| 2152 | Incremented by one each time an instance of |
| 2153 | <B>bash</B> |
| 2154 | |
| 2155 | is started. |
| 2156 | <DT><B>UID</B> |
| 2157 | |
| 2158 | <DD> |
| 2159 | Expands to the user ID of the current user, initialized at shell startup. |
| 2160 | This variable is readonly. |
| 2161 | |
| 2162 | </DL> |
| 2163 | <P> |
| 2164 | |
| 2165 | The following variables are used by the shell. In some cases, |
| 2166 | <B>bash</B> |
| 2167 | |
| 2168 | assigns a default value to a variable; these cases are noted |
| 2169 | below. |
| 2170 | <P> |
| 2171 | |
| 2172 | |
| 2173 | <DL COMPACT> |
| 2174 | <DT><B>BASH_ENV</B> |
| 2175 | |
| 2176 | <DD> |
| 2177 | If this parameter is set when <B>bash</B> is executing a shell script, |
| 2178 | its value is interpreted as a filename containing commands to |
| 2179 | initialize the shell, as in |
| 2180 | <A HREF="file:~/.bashrc"><I>~/.bashrc</I></A>. |
| 2181 | |
| 2182 | The value of |
| 2183 | <FONT SIZE=-1><B>BASH_ENV</B> |
| 2184 | |
| 2185 | </FONT> |
| 2186 | is subjected to parameter expansion, command substitution, and arithmetic |
| 2187 | expansion before being interpreted as a file name. |
| 2188 | <FONT SIZE=-1><B>PATH</B> |
| 2189 | |
| 2190 | </FONT> |
| 2191 | is not used to search for the resultant file name. |
| 2192 | <DT><B>CDPATH</B> |
| 2193 | |
| 2194 | <DD> |
| 2195 | The search path for the |
| 2196 | <B>cd</B> |
| 2197 | |
| 2198 | command. |
| 2199 | This is a colon-separated list of directories in which the shell looks |
| 2200 | for destination directories specified by the |
| 2201 | <B>cd</B> |
| 2202 | |
| 2203 | command. |
| 2204 | A sample value is |
| 2205 | <TT>".:~:/usr"</TT>. |
| 2206 | |
| 2207 | <DT><B>COLUMNS</B> |
| 2208 | |
| 2209 | <DD> |
| 2210 | Used by the <B>select</B> builtin command to determine the terminal width |
| 2211 | when printing selection lists. Automatically set upon receipt of a SIGWINCH. |
| 2212 | <DT><B>COMPREPLY</B> |
| 2213 | |
| 2214 | <DD> |
| 2215 | An array variable from which <B>bash</B> reads the possible completions |
| 2216 | generated by a shell function invoked by the programmable completion |
| 2217 | facility (see <B>Programmable Completion</B> below). |
| 2218 | <DT><B>EMACS</B> |
| 2219 | |
| 2220 | <DD> |
| 2221 | If <B>bash</B> finds this variable in the environment when the shell starts |
| 2222 | with value |
| 2223 | <TT>t</TT>, |
| 2224 | |
| 2225 | it assumes that the shell is running in an emacs shell buffer and disables |
| 2226 | line editing. |
| 2227 | <DT><B>FCEDIT</B> |
| 2228 | |
| 2229 | <DD> |
| 2230 | The default editor for the |
| 2231 | <B>fc</B> |
| 2232 | |
| 2233 | builtin command. |
| 2234 | <DT><B>FIGNORE</B> |
| 2235 | |
| 2236 | <DD> |
| 2237 | A colon-separated list of suffixes to ignore when performing |
| 2238 | filename completion (see |
| 2239 | <FONT SIZE=-1><B>READLINE</B> |
| 2240 | |
| 2241 | </FONT> |
| 2242 | below). |
| 2243 | A filename whose suffix matches one of the entries in |
| 2244 | <FONT SIZE=-1><B>FIGNORE</B> |
| 2245 | |
| 2246 | </FONT> |
| 2247 | is excluded from the list of matched filenames. |
| 2248 | A sample value is |
| 2249 | <TT>".o:~"</TT>. |
| 2250 | |
| 2251 | <DT><B>GLOBIGNORE</B> |
| 2252 | |
| 2253 | <DD> |
| 2254 | A colon-separated list of patterns defining the set of filenames to |
| 2255 | be ignored by pathname expansion. |
| 2256 | If a filename matched by a pathname expansion pattern also matches one |
| 2257 | of the patterns in |
| 2258 | <FONT SIZE=-1><B>GLOBIGNORE</B>, |
| 2259 | |
| 2260 | </FONT> |
| 2261 | it is removed from the list of matches. |
| 2262 | <DT><B>HISTCONTROL</B> |
| 2263 | |
| 2264 | <DD> |
| 2265 | A colon-separated list of values controlling how commands are saved on |
| 2266 | the history list. |
| 2267 | If the list of values includes |
| 2268 | <I>ignorespace</I>, |
| 2269 | |
| 2270 | lines which begin with a |
| 2271 | <B>space</B> |
| 2272 | |
| 2273 | character are not saved in the history list. |
| 2274 | A value of |
| 2275 | <I>ignoredups</I> |
| 2276 | |
| 2277 | causes lines matching the previous history entry to not be saved. |
| 2278 | A value of |
| 2279 | <I>ignoreboth</I> |
| 2280 | |
| 2281 | is shorthand for <I>ignorespace</I> and <I>ignoredups</I>. |
| 2282 | A value of |
| 2283 | <I>erasedups</I> |
| 2284 | |
| 2285 | causes all previous lines matching the current line to be removed from |
| 2286 | the history list before that line is saved. |
| 2287 | Any value not in the above list is ignored. |
| 2288 | If <B>HISTCONTROL</B> is unset, or does not include a valid value, |
| 2289 | all lines read by the shell parser are saved on the history list, |
| 2290 | subject to the value of |
| 2291 | <B>HISTIGNORE</B>. |
| 2292 | |
| 2293 | The second and subsequent lines of a multi-line compound command are |
| 2294 | not tested, and are added to the history regardless of the value of |
| 2295 | <B>HISTCONTROL</B>. |
| 2296 | |
| 2297 | <DT><B>HISTFILE</B> |
| 2298 | |
| 2299 | <DD> |
| 2300 | The name of the file in which command history is saved (see |
| 2301 | <FONT SIZE=-1><B>HISTORY</B> |
| 2302 | |
| 2303 | </FONT> |
| 2304 | below). The default value is <A HREF="file:~/.bash_history"><I>~/.bash_history</I></A>. If unset, the |
| 2305 | command history is not saved when an interactive shell exits. |
| 2306 | <DT><B>HISTFILESIZE</B> |
| 2307 | |
| 2308 | <DD> |
| 2309 | The maximum number of lines contained in the history file. When this |
| 2310 | variable is assigned a value, the history file is truncated, if |
| 2311 | necessary, by removing the oldest entries, |
| 2312 | to contain no more than that number of lines. The default |
| 2313 | value is 500. The history file is also truncated to this size after |
| 2314 | writing it when an interactive shell exits. |
| 2315 | <DT><B>HISTIGNORE</B> |
| 2316 | |
| 2317 | <DD> |
| 2318 | A colon-separated list of patterns used to decide which command lines |
| 2319 | should be saved on the history list. Each pattern is anchored at the |
| 2320 | beginning of the line and must match the complete line (no implicit |
| 2321 | `<B>*</B>' is appended). Each pattern is tested against the line |
| 2322 | after the checks specified by |
| 2323 | <B>HISTCONTROL</B> |
| 2324 | |
| 2325 | are applied. |
| 2326 | In addition to the normal shell pattern matching characters, `<B>&</B>' |
| 2327 | matches the previous history line. `<B>&</B>' may be escaped using a |
| 2328 | backslash; the backslash is removed before attempting a match. |
| 2329 | The second and subsequent lines of a multi-line compound command are |
| 2330 | not tested, and are added to the history regardless of the value of |
| 2331 | <B>HISTIGNORE</B>. |
| 2332 | |
| 2333 | <DT><B>HISTSIZE</B> |
| 2334 | |
| 2335 | <DD> |
| 2336 | The number of commands to remember in the command history (see |
| 2337 | <FONT SIZE=-1><B>HISTORY</B> |
| 2338 | |
| 2339 | </FONT> |
| 2340 | below). The default value is 500. |
| 2341 | <DT><B>HISTTIMEFORMAT</B> |
| 2342 | |
| 2343 | <DD> |
| 2344 | If this variable is set and not null, its value is used as a format string |
| 2345 | for <I>strftime</I>(3) to print the time stamp associated with each history |
| 2346 | entry displayed by the <B>history</B> builtin. |
| 2347 | If this variable is set, time stamps are written to the history file so |
| 2348 | they may be preserved across shell sessions. |
| 2349 | This uses the history comment character to distinguish timestamps from |
| 2350 | other history lines. |
| 2351 | <DT><B>HOME</B> |
| 2352 | |
| 2353 | <DD> |
| 2354 | The home directory of the current user; the default argument for the |
| 2355 | <B>cd</B> builtin command. |
| 2356 | The value of this variable is also used when performing tilde expansion. |
| 2357 | <DT><B>HOSTFILE</B> |
| 2358 | |
| 2359 | <DD> |
| 2360 | Contains the name of a file in the same format as |
| 2361 | |
| 2362 | <I>/etc/hosts</I> |
| 2363 | |
| 2364 | that should be read when the shell needs to complete a |
| 2365 | hostname. |
| 2366 | The list of possible hostname completions may be changed while the |
| 2367 | shell is running; |
| 2368 | the next time hostname completion is attempted after the |
| 2369 | value is changed, |
| 2370 | <B>bash</B> |
| 2371 | |
| 2372 | adds the contents of the new file to the existing list. |
| 2373 | If |
| 2374 | <FONT SIZE=-1><B>HOSTFILE</B> |
| 2375 | |
| 2376 | </FONT> |
| 2377 | is set, but has no value, <B>bash</B> attempts to read |
| 2378 | |
| 2379 | <I>/etc/hosts</I> |
| 2380 | |
| 2381 | to obtain the list of possible hostname completions. |
| 2382 | When |
| 2383 | <FONT SIZE=-1><B>HOSTFILE</B> |
| 2384 | |
| 2385 | </FONT> |
| 2386 | is unset, the hostname list is cleared. |
| 2387 | <DT><B>IFS</B> |
| 2388 | |
| 2389 | <DD> |
| 2390 | The |
| 2391 | <I>Internal Field Separator</I> |
| 2392 | |
| 2393 | that is used |
| 2394 | for word splitting after expansion and to |
| 2395 | split lines into words with the |
| 2396 | <B>read</B> |
| 2397 | |
| 2398 | builtin command. The default value is |
| 2399 | ``<space><tab><newline>''. |
| 2400 | <DT><B>IGNOREEOF</B> |
| 2401 | |
| 2402 | <DD> |
| 2403 | Controls the |
| 2404 | action of an interactive shell on receipt of an |
| 2405 | <FONT SIZE=-1><B>EOF</B> |
| 2406 | |
| 2407 | </FONT> |
| 2408 | character as the sole input. If set, the value is the number of |
| 2409 | consecutive |
| 2410 | <FONT SIZE=-1><B>EOF</B> |
| 2411 | |
| 2412 | </FONT> |
| 2413 | characters which must be |
| 2414 | typed as the first characters on an input line before |
| 2415 | <B>bash</B> |
| 2416 | |
| 2417 | exits. If the variable exists but does not have a numeric value, or |
| 2418 | has no value, the default value is 10. If it does not exist, |
| 2419 | <FONT SIZE=-1><B>EOF</B> |
| 2420 | |
| 2421 | </FONT> |
| 2422 | signifies the end of input to the shell. |
| 2423 | <DT><B>INPUTRC</B> |
| 2424 | |
| 2425 | <DD> |
| 2426 | The filename for the |
| 2427 | <B>readline</B> |
| 2428 | |
| 2429 | startup file, overriding the default of |
| 2430 | |
| 2431 | <A HREF="file:~/.inputrc"><I>~/.inputrc</I></A> |
| 2432 | |
| 2433 | (see |
| 2434 | <FONT SIZE=-1><B>READLINE</B> |
| 2435 | |
| 2436 | </FONT> |
| 2437 | below). |
| 2438 | <DT><B>LANG</B> |
| 2439 | |
| 2440 | <DD> |
| 2441 | Used to determine the locale category for any category not specifically |
| 2442 | selected with a variable starting with <B>LC_</B>. |
| 2443 | <DT><B>LC_ALL</B> |
| 2444 | |
| 2445 | <DD> |
| 2446 | This variable overrides the value of <B>LANG</B> and any other |
| 2447 | <B>LC_</B> variable specifying a locale category. |
| 2448 | <DT><B>LC_COLLATE</B> |
| 2449 | |
| 2450 | <DD> |
| 2451 | This variable determines the collation order used when sorting the |
| 2452 | results of pathname expansion, and determines the behavior of range |
| 2453 | expressions, equivalence classes, and collating sequences within |
| 2454 | pathname expansion and pattern matching. |
| 2455 | <DT><B>LC_CTYPE</B> |
| 2456 | |
| 2457 | <DD> |
| 2458 | This variable determines the interpretation of characters and the |
| 2459 | behavior of character classes within pathname expansion and pattern |
| 2460 | matching. |
| 2461 | <DT><B>LC_MESSAGES</B> |
| 2462 | |
| 2463 | <DD> |
| 2464 | This variable determines the locale used to translate double-quoted |
| 2465 | strings preceded by a <B>$</B>. |
| 2466 | <DT><B>LC_NUMERIC</B> |
| 2467 | |
| 2468 | <DD> |
| 2469 | This variable determines the locale category used for number formatting. |
| 2470 | <DT><B>LINES</B> |
| 2471 | |
| 2472 | <DD> |
| 2473 | Used by the <B>select</B> builtin command to determine the column length |
| 2474 | for printing selection lists. Automatically set upon receipt of a SIGWINCH. |
| 2475 | <DT><B>MAIL</B> |
| 2476 | |
| 2477 | <DD> |
| 2478 | If this parameter is set to a file name and the |
| 2479 | <FONT SIZE=-1><B>MAILPATH</B> |
| 2480 | |
| 2481 | </FONT> |
| 2482 | variable is not set, |
| 2483 | <B>bash</B> |
| 2484 | |
| 2485 | informs the user of the arrival of mail in the specified file. |
| 2486 | <DT><B>MAILCHECK</B> |
| 2487 | |
| 2488 | <DD> |
| 2489 | Specifies how |
| 2490 | often (in seconds) |
| 2491 | <B>bash</B> |
| 2492 | |
| 2493 | checks for mail. The default is 60 seconds. When it is time to check |
| 2494 | for mail, the shell does so before displaying the primary prompt. |
| 2495 | If this variable is unset, or set to a value that is not a number |
| 2496 | greater than or equal to zero, the shell disables mail checking. |
| 2497 | <DT><B>MAILPATH</B> |
| 2498 | |
| 2499 | <DD> |
| 2500 | A colon-separated list of file names to be checked for mail. |
| 2501 | The message to be printed when mail arrives in a particular file |
| 2502 | may be specified by separating the file name from the message with a `?'. |
| 2503 | When used in the text of the message, <B>$_</B> expands to the name of |
| 2504 | the current mailfile. |
| 2505 | Example: |
| 2506 | <DL COMPACT><DT><DD> |
| 2507 | <P> |
| 2508 | |
| 2509 | <B>MAILPATH</B>=aq/var/mail/bfox?"You have mail":~/shell-mail?"$_ has mail!"aq |
| 2510 | <P> |
| 2511 | |
| 2512 | <B>Bash</B> |
| 2513 | |
| 2514 | supplies a default value for this variable, but the location of the user |
| 2515 | mail files that it uses is system dependent (e.g., /var/mail/<B>$USER</B>). |
| 2516 | </DL> |
| 2517 | |
| 2518 | <DT><B>OPTERR</B> |
| 2519 | |
| 2520 | <DD> |
| 2521 | If set to the value 1, |
| 2522 | <B>bash</B> |
| 2523 | |
| 2524 | displays error messages generated by the |
| 2525 | <B>getopts</B> |
| 2526 | |
| 2527 | builtin command (see |
| 2528 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 2529 | |
| 2530 | </FONT> |
| 2531 | below). |
| 2532 | <FONT SIZE=-1><B>OPTERR</B> |
| 2533 | |
| 2534 | </FONT> |
| 2535 | is initialized to 1 each time the shell is invoked or a shell |
| 2536 | script is executed. |
| 2537 | <DT><B>PATH</B> |
| 2538 | |
| 2539 | <DD> |
| 2540 | The search path for commands. It |
| 2541 | is a colon-separated list of directories in which |
| 2542 | the shell looks for commands (see |
| 2543 | <FONT SIZE=-1><B>COMMAND EXECUTION</B> |
| 2544 | |
| 2545 | </FONT> |
| 2546 | below). |
| 2547 | A zero-length (null) directory name in the value of <B>PATH</B> indicates the |
| 2548 | current directory. |
| 2549 | A null directory name may appear as two adjacent colons, or as an initial |
| 2550 | or trailing colon. |
| 2551 | The default path is system-dependent, |
| 2552 | and is set by the administrator who installs |
| 2553 | <B>bash</B>. |
| 2554 | |
| 2555 | A common value is |
| 2556 | <TT>/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin</TT>. |
| 2557 | |
| 2558 | <DT><B>POSIXLY_CORRECT</B> |
| 2559 | |
| 2560 | <DD> |
| 2561 | If this variable is in the environment when <B>bash</B> starts, the shell |
| 2562 | enters <I>posix mode</I> before reading the startup files, as if the |
| 2563 | <B>--posix</B> |
| 2564 | |
| 2565 | invocation option had been supplied. If it is set while the shell is |
| 2566 | running, <B>bash</B> enables <I>posix mode</I>, as if the command |
| 2567 | <TT>set -o posix</TT> |
| 2568 | |
| 2569 | had been executed. |
| 2570 | <DT><B>PROMPT_COMMAND</B> |
| 2571 | |
| 2572 | <DD> |
| 2573 | If set, the value is executed as a command prior to issuing each primary |
| 2574 | prompt. |
| 2575 | <DT><B>PROMPT_DIRTRIM</B> |
| 2576 | |
| 2577 | <DD> |
| 2578 | If set to a number greater than zero, the value is used as the number of |
| 2579 | trailing directory components to retain when expanding the <B>\w and |
| 2580 | \W</B> prompt string escapes (see |
| 2581 | <FONT SIZE=-1><B>PROMPTING</B> |
| 2582 | |
| 2583 | </FONT> |
| 2584 | below). Characters removed are replaced with an ellipsis. |
| 2585 | <DT><B>PS1</B> |
| 2586 | |
| 2587 | <DD> |
| 2588 | The value of this parameter is expanded (see |
| 2589 | <FONT SIZE=-1><B>PROMPTING</B> |
| 2590 | |
| 2591 | </FONT> |
| 2592 | below) and used as the primary prompt string. The default value is |
| 2593 | ``<B>\s-\v\$ </B>''. |
| 2594 | <DT><B>PS2</B> |
| 2595 | |
| 2596 | <DD> |
| 2597 | The value of this parameter is expanded as with |
| 2598 | <B>PS1</B> |
| 2599 | |
| 2600 | and used as the secondary prompt string. The default is |
| 2601 | ``<B>> </B>''. |
| 2602 | <DT><B>PS3</B> |
| 2603 | |
| 2604 | <DD> |
| 2605 | The value of this parameter is used as the prompt for the |
| 2606 | <B>select</B> |
| 2607 | |
| 2608 | command (see |
| 2609 | <FONT SIZE=-1><B>SHELL GRAMMAR</B> |
| 2610 | |
| 2611 | </FONT> |
| 2612 | above). |
| 2613 | <DT><B>PS4</B> |
| 2614 | |
| 2615 | <DD> |
| 2616 | The value of this parameter is expanded as with |
| 2617 | <B>PS1</B> |
| 2618 | |
| 2619 | and the value is printed before each command |
| 2620 | <B>bash</B> |
| 2621 | |
| 2622 | displays during an execution trace. The first character of |
| 2623 | <FONT SIZE=-1><B>PS4</B> |
| 2624 | |
| 2625 | </FONT> |
| 2626 | is replicated multiple times, as necessary, to indicate multiple |
| 2627 | levels of indirection. The default is ``<B>+ </B>''. |
| 2628 | <DT><B>SHELL</B> |
| 2629 | |
| 2630 | <DD> |
| 2631 | The full pathname to the shell is kept in this environment variable. |
| 2632 | If it is not set when the shell starts, |
| 2633 | <B>bash</B> |
| 2634 | |
| 2635 | assigns to it the full pathname of the current user's login shell. |
| 2636 | <DT><B>TIMEFORMAT</B> |
| 2637 | |
| 2638 | <DD> |
| 2639 | The value of this parameter is used as a format string specifying |
| 2640 | how the timing information for pipelines prefixed with the |
| 2641 | <B>time</B> |
| 2642 | |
| 2643 | reserved word should be displayed. |
| 2644 | The <B>%</B> character introduces an escape sequence that is |
| 2645 | expanded to a time value or other information. |
| 2646 | The escape sequences and their meanings are as follows; the |
| 2647 | braces denote optional portions. |
| 2648 | <P> |
| 2649 | <DL COMPACT><DT><DD> |
| 2650 | |
| 2651 | <DL COMPACT> |
| 2652 | <DT><B>%%</B> |
| 2653 | |
| 2654 | <DD> |
| 2655 | A literal <B>%</B>. |
| 2656 | <DT><B>%[</B><I>p</I>][l]R |
| 2657 | |
| 2658 | <DD> |
| 2659 | The elapsed time in seconds. |
| 2660 | <DT><B>%[</B><I>p</I>][l]U |
| 2661 | |
| 2662 | <DD> |
| 2663 | The number of CPU seconds spent in user mode. |
| 2664 | <DT><B>%[</B><I>p</I>][l]S |
| 2665 | |
| 2666 | <DD> |
| 2667 | The number of CPU seconds spent in system mode. |
| 2668 | <DT><B>%P</B> |
| 2669 | |
| 2670 | <DD> |
| 2671 | The CPU percentage, computed as (%U + %S) / %R. |
| 2672 | |
| 2673 | </DL></DL> |
| 2674 | |
| 2675 | <DT><DD> |
| 2676 | The optional <I>p</I> is a digit specifying the <I>precision</I>, |
| 2677 | the number of fractional digits after a decimal point. |
| 2678 | A value of 0 causes no decimal point or fraction to be output. |
| 2679 | At most three places after the decimal point may be specified; |
| 2680 | values of <I>p</I> greater than 3 are changed to 3. |
| 2681 | If <I>p</I> is not specified, the value 3 is used. |
| 2682 | <DT><DD> |
| 2683 | The optional <B>l</B> specifies a longer format, including |
| 2684 | minutes, of the form <I>MM</I>m<I>SS</I>.<I>FF</I>s. |
| 2685 | The value of <I>p</I> determines whether or not the fraction is |
| 2686 | included. |
| 2687 | <DT><DD> |
| 2688 | If this variable is not set, <B>bash</B> acts as if it had the |
| 2689 | value <B>$aq\nreal\t%3lR\nuser\t%3lU\nsys %3lSaq</B>. |
| 2690 | If the value is null, no timing information is displayed. |
| 2691 | A trailing newline is added when the format string is displayed. |
| 2692 | <DT><B>TMOUT</B> |
| 2693 | |
| 2694 | <DD> |
| 2695 | If set to a value greater than zero, <B>TMOUT</B> is treated as the |
| 2696 | default timeout for the <B>read</B> builtin. |
| 2697 | The <B>select</B> command terminates if input does not arrive |
| 2698 | after <B>TMOUT</B> seconds when input is coming from a terminal. |
| 2699 | In an interactive shell, the value is interpreted as the |
| 2700 | number of seconds to wait for input after issuing the primary prompt. |
| 2701 | <B>Bash</B> |
| 2702 | |
| 2703 | terminates after waiting for that number of seconds if input does |
| 2704 | not arrive. |
| 2705 | <DT><B>TMPDIR</B> |
| 2706 | |
| 2707 | <DD> |
| 2708 | If set, <B>Bash</B> uses its value as the name of a directory in which |
| 2709 | <B>Bash</B> creates temporary files for the shell's use. |
| 2710 | <DT><B>auto_resume</B> |
| 2711 | |
| 2712 | <DD> |
| 2713 | This variable controls how the shell interacts with the user and |
| 2714 | job control. If this variable is set, single word simple |
| 2715 | commands without redirections are treated as candidates for resumption |
| 2716 | of an existing stopped job. There is no ambiguity allowed; if there is |
| 2717 | more than one job beginning with the string typed, the job most recently |
| 2718 | accessed is selected. The |
| 2719 | <I>name</I> |
| 2720 | |
| 2721 | of a stopped job, in this context, is the command line used to |
| 2722 | start it. |
| 2723 | If set to the value |
| 2724 | <I>exact</I>, |
| 2725 | |
| 2726 | the string supplied must match the name of a stopped job exactly; |
| 2727 | if set to |
| 2728 | <I>substring</I>, |
| 2729 | |
| 2730 | the string supplied needs to match a substring of the name of a |
| 2731 | stopped job. The |
| 2732 | <I>substring</I> |
| 2733 | |
| 2734 | value provides functionality analogous to the |
| 2735 | <B>%?</B> |
| 2736 | |
| 2737 | job identifier (see |
| 2738 | <FONT SIZE=-1><B>JOB CONTROL</B> |
| 2739 | |
| 2740 | </FONT> |
| 2741 | below). If set to any other value, the supplied string must |
| 2742 | be a prefix of a stopped job's name; this provides functionality |
| 2743 | analogous to the <B>%</B><I>string</I> job identifier. |
| 2744 | <DT><B>histchars</B> |
| 2745 | |
| 2746 | <DD> |
| 2747 | The two or three characters which control history expansion |
| 2748 | and tokenization (see |
| 2749 | <FONT SIZE=-1><B>HISTORY EXPANSION</B> |
| 2750 | |
| 2751 | </FONT> |
| 2752 | below). The first character is the <I>history expansion</I> character, |
| 2753 | the character which signals the start of a history |
| 2754 | expansion, normally `<B>!</B>'. |
| 2755 | The second character is the <I>quick substitution</I> |
| 2756 | character, which is used as shorthand for re-running the previous |
| 2757 | command entered, substituting one string for another in the command. |
| 2758 | The default is `<B>^</B>'. |
| 2759 | The optional third character is the character |
| 2760 | which indicates that the remainder of the line is a comment when found |
| 2761 | as the first character of a word, normally `<B>#</B>'. The history |
| 2762 | comment character causes history substitution to be skipped for the |
| 2763 | remaining words on the line. It does not necessarily cause the shell |
| 2764 | parser to treat the rest of the line as a comment. |
| 2765 | |
| 2766 | </DL> |
| 2767 | <A NAME="lbAX"> </A> |
| 2768 | <H4>Arrays</H4> |
| 2769 | |
| 2770 | <B>Bash</B> |
| 2771 | |
| 2772 | provides one-dimensional indexed and associative array variables. |
| 2773 | Any variable may be used as an indexed array; the |
| 2774 | <B>declare</B> |
| 2775 | |
| 2776 | builtin will explicitly declare an array. |
| 2777 | There is no maximum |
| 2778 | limit on the size of an array, nor any requirement that members |
| 2779 | be indexed or assigned contiguously. |
| 2780 | Indexed arrays are referenced using integers (including arithmetic |
| 2781 | expressions) and are zero-based; associative arrays are referenced |
| 2782 | using arbitrary strings. |
| 2783 | <P> |
| 2784 | |
| 2785 | An indexed array is created automatically if any variable is assigned to |
| 2786 | using the syntax <I>name</I>[<I>subscript</I>]=<I>value</I>. The |
| 2787 | <I>subscript</I> |
| 2788 | |
| 2789 | is treated as an arithmetic expression that must evaluate to a number |
| 2790 | greater than or equal to zero. To explicitly declare an indexed array, |
| 2791 | use |
| 2792 | <B>declare -a </B><I>name</I> |
| 2793 | |
| 2794 | (see |
| 2795 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 2796 | |
| 2797 | </FONT> |
| 2798 | below). |
| 2799 | <B>declare -a </B><I>name</I>[<I>subscript</I>] |
| 2800 | |
| 2801 | is also accepted; the <I>subscript</I> is ignored. |
| 2802 | <P> |
| 2803 | |
| 2804 | Associative arrays are created using |
| 2805 | <B>declare -A </B><I>name</I>. |
| 2806 | |
| 2807 | <P> |
| 2808 | |
| 2809 | Attributes may be |
| 2810 | specified for an array variable using the |
| 2811 | <B>declare</B> |
| 2812 | |
| 2813 | and |
| 2814 | <B>readonly</B> |
| 2815 | |
| 2816 | builtins. Each attribute applies to all members of an array. |
| 2817 | <P> |
| 2818 | |
| 2819 | Arrays are assigned to using compound assignments of the form |
| 2820 | <I>name</I>=<B>(</B>value<I>1</I> ... value<I>n</I><B>)</B>, where each |
| 2821 | <I>value</I> is of the form [<I>subscript</I>]=<I>string</I>. |
| 2822 | Indexed array assignments do not require the bracket and subscript. |
| 2823 | When assigning to indexed arrays, if the optional brackets and subscript |
| 2824 | are supplied, that index is assigned to; |
| 2825 | otherwise the index of the element assigned is the last index assigned |
| 2826 | to by the statement plus one. Indexing starts at zero. |
| 2827 | <P> |
| 2828 | |
| 2829 | When assigning to an associative array, the subscript is required. |
| 2830 | <P> |
| 2831 | |
| 2832 | This syntax is also accepted by the |
| 2833 | <B>declare</B> |
| 2834 | |
| 2835 | builtin. Individual array elements may be assigned to using the |
| 2836 | <I>name</I>[<I>subscript</I>]=<I>value</I> syntax introduced above. |
| 2837 | <P> |
| 2838 | |
| 2839 | Any element of an array may be referenced using |
| 2840 | ${<I>name</I>[<I>subscript</I>]}. The braces are required to avoid |
| 2841 | conflicts with pathname expansion. If |
| 2842 | <I>subscript</I> is <B>@</B> or <B>*</B>, the word expands to |
| 2843 | all members of <I>name</I>. These subscripts differ only when the |
| 2844 | word appears within double quotes. If the word is double-quoted, |
| 2845 | ${<I>name</I>[*]} expands to a single |
| 2846 | word with the value of each array member separated by the first |
| 2847 | character of the |
| 2848 | <FONT SIZE=-1><B>IFS</B> |
| 2849 | |
| 2850 | </FONT> |
| 2851 | special variable, and ${<I>name</I>[@]} expands each element of |
| 2852 | <I>name</I> to a separate word. When there are no array members, |
| 2853 | ${<I>name</I>[@]} expands to nothing. |
| 2854 | If the double-quoted expansion occurs within a word, the expansion of |
| 2855 | the first parameter is joined with the beginning part of the original |
| 2856 | word, and the expansion of the last parameter is joined with the last |
| 2857 | part of the original word. |
| 2858 | This is analogous to the expansion |
| 2859 | of the special parameters <B>*</B> and <B>@</B> (see |
| 2860 | <B>Special Parameters</B> |
| 2861 | |
| 2862 | above). ${#<I>name</I>[<I>subscript</I>]} expands to the length of |
| 2863 | ${<I>name</I>[<I>subscript</I>]}. If <I>subscript</I> is <B>*</B> or |
| 2864 | <B>@</B>, the expansion is the number of elements in the array. |
| 2865 | Referencing an array variable without a subscript is equivalent to |
| 2866 | referencing the array with a subscript of 0. |
| 2867 | <P> |
| 2868 | |
| 2869 | The |
| 2870 | <B>unset</B> |
| 2871 | |
| 2872 | builtin is used to destroy arrays. <B>unset</B> <I>name</I>[<I>subscript</I>] |
| 2873 | destroys the array element at index <I>subscript</I>. |
| 2874 | Care must be taken to avoid unwanted side effects caused by filename |
| 2875 | generation. |
| 2876 | <B>unset</B> <I>name</I>, where <I>name</I> is an array, or |
| 2877 | <B>unset</B> <I>name</I>[<I>subscript</I>], where |
| 2878 | <I>subscript</I> is <B>*</B> or <B>@</B>, removes the entire array. |
| 2879 | <P> |
| 2880 | |
| 2881 | The |
| 2882 | <B>declare</B>, |
| 2883 | |
| 2884 | <B>local</B>, |
| 2885 | |
| 2886 | and |
| 2887 | <B>readonly</B> |
| 2888 | |
| 2889 | builtins each accept a |
| 2890 | <B>-a</B> |
| 2891 | |
| 2892 | option to specify an indexed array and a |
| 2893 | <B>-A</B> |
| 2894 | |
| 2895 | option to specify an associative array. |
| 2896 | The |
| 2897 | <B>read</B> |
| 2898 | |
| 2899 | builtin accepts a |
| 2900 | <B>-a</B> |
| 2901 | |
| 2902 | option to assign a list of words read from the standard input |
| 2903 | to an array. The |
| 2904 | <B>set</B> |
| 2905 | |
| 2906 | and |
| 2907 | <B>declare</B> |
| 2908 | |
| 2909 | builtins display array values in a way that allows them to be |
| 2910 | reused as assignments. |
| 2911 | <A NAME="lbAY"> </A> |
| 2912 | <H3>EXPANSION</H3> |
| 2913 | |
| 2914 | Expansion is performed on the command line after it has been split into |
| 2915 | words. There are seven kinds of expansion performed: |
| 2916 | <I>brace expansion</I>, |
| 2917 | |
| 2918 | <I>tilde expansion</I>, |
| 2919 | |
| 2920 | <I>parameter and variable expansion</I>, |
| 2921 | |
| 2922 | <I>command substitution</I>, |
| 2923 | |
| 2924 | <I>arithmetic expansion</I>, |
| 2925 | |
| 2926 | <I>word splitting</I>, |
| 2927 | |
| 2928 | and |
| 2929 | <I>pathname expansion</I>. |
| 2930 | |
| 2931 | <P> |
| 2932 | |
| 2933 | The order of expansions is: brace expansion, tilde expansion, |
| 2934 | parameter, variable and arithmetic expansion and |
| 2935 | command substitution |
| 2936 | (done in a left-to-right fashion), word splitting, and pathname |
| 2937 | expansion. |
| 2938 | <P> |
| 2939 | |
| 2940 | On systems that can support it, there is an additional expansion |
| 2941 | available: <I>process substitution</I>. |
| 2942 | <P> |
| 2943 | |
| 2944 | Only brace expansion, word splitting, and pathname expansion |
| 2945 | can change the number of words of the expansion; other expansions |
| 2946 | expand a single word to a single word. |
| 2947 | The only exceptions to this are the expansions of |
| 2948 | "<B>$@</B>" and "<B>${</B><I>name</I><B>[@]}</B>" |
| 2949 | as explained above (see |
| 2950 | <FONT SIZE=-1><B>PARAMETERS</B>). |
| 2951 | |
| 2952 | </FONT> |
| 2953 | <A NAME="lbAZ"> </A> |
| 2954 | <H4>Brace Expansion</H4> |
| 2955 | |
| 2956 | <P> |
| 2957 | |
| 2958 | <I>Brace expansion</I> |
| 2959 | |
| 2960 | is a mechanism by which arbitrary strings |
| 2961 | may be generated. This mechanism is similar to |
| 2962 | <I>pathname expansion</I>, but the filenames generated |
| 2963 | need not exist. Patterns to be brace expanded take |
| 2964 | the form of an optional |
| 2965 | <I>preamble</I>, |
| 2966 | |
| 2967 | followed by either a series of comma-separated strings or |
| 2968 | a sequence expression between a pair of braces, followed by |
| 2969 | an optional |
| 2970 | <I>postscript</I>. |
| 2971 | |
| 2972 | The preamble is prefixed to each string contained |
| 2973 | within the braces, and the postscript is then appended |
| 2974 | to each resulting string, expanding left to right. |
| 2975 | <P> |
| 2976 | |
| 2977 | Brace expansions may be nested. The results of each expanded |
| 2978 | string are not sorted; left to right order is preserved. |
| 2979 | For example, a<B>{</B>d,c,b<B>}</B>e expands into `ade ace abe'. |
| 2980 | <P> |
| 2981 | |
| 2982 | A sequence expression takes the form |
| 2983 | <B>{</B><I>x</I><B>..</B><I>y</I><B>[..</B><I>incr</I><B>]}</B>, |
| 2984 | where <I>x</I> and <I>y</I> are either integers or single characters, |
| 2985 | and <I>incr</I>, an optional increment, is an integer. |
| 2986 | When integers are supplied, the expression expands to each number between |
| 2987 | <I>x</I> and <I>y</I>, inclusive. |
| 2988 | Supplied integers may be prefixed with <I>0</I> to force each term to have the |
| 2989 | same width. When either <I>x</I> or y begins with a zero, the shell |
| 2990 | attempts to force all generated terms to contain the same number of digits, |
| 2991 | zero-padding where necessary. |
| 2992 | When characters are supplied, the expression expands to each character |
| 2993 | lexicographically between <I>x</I> and <I>y</I>, inclusive. Note that |
| 2994 | both <I>x</I> and <I>y</I> must be of the same type. |
| 2995 | When the increment is supplied, it is used as the difference between |
| 2996 | each term. The default increment is 1 or -1 as appropriate. |
| 2997 | <P> |
| 2998 | |
| 2999 | Brace expansion is performed before any other expansions, |
| 3000 | and any characters special to other expansions are preserved |
| 3001 | in the result. It is strictly textual. |
| 3002 | <B>Bash</B> |
| 3003 | |
| 3004 | does not apply any syntactic interpretation to the context of the |
| 3005 | expansion or the text between the braces. |
| 3006 | <P> |
| 3007 | |
| 3008 | A correctly-formed brace expansion must contain unquoted opening |
| 3009 | and closing braces, and at least one unquoted comma or a valid |
| 3010 | sequence expression. |
| 3011 | Any incorrectly formed brace expansion is left unchanged. |
| 3012 | A <B>{</B> or <B>,</B> may be quoted with a backslash to prevent its |
| 3013 | being considered part of a brace expression. |
| 3014 | To avoid conflicts with parameter expansion, the string <B>${</B> |
| 3015 | is not considered eligible for brace expansion. |
| 3016 | <P> |
| 3017 | |
| 3018 | This construct is typically used as shorthand when the common |
| 3019 | prefix of the strings to be generated is longer than in the |
| 3020 | above example: |
| 3021 | <DL COMPACT><DT><DD> |
| 3022 | <P> |
| 3023 | |
| 3024 | mkdir /usr/local/src/bash/{old,new,dist,bugs} |
| 3025 | </DL> |
| 3026 | |
| 3027 | or |
| 3028 | <DL COMPACT><DT><DD> |
| 3029 | chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}} |
| 3030 | </DL> |
| 3031 | |
| 3032 | <P> |
| 3033 | |
| 3034 | Brace expansion introduces a slight incompatibility with |
| 3035 | historical versions of |
| 3036 | <B>sh</B>. |
| 3037 | |
| 3038 | <B>sh</B> |
| 3039 | |
| 3040 | does not treat opening or closing braces specially when they |
| 3041 | appear as part of a word, and preserves them in the output. |
| 3042 | <B>Bash</B> |
| 3043 | |
| 3044 | removes braces from words as a consequence of brace |
| 3045 | expansion. For example, a word entered to |
| 3046 | <B>sh</B> |
| 3047 | |
| 3048 | as <I>file{1,2}</I> |
| 3049 | appears identically in the output. The same word is |
| 3050 | output as |
| 3051 | <I>file1 file2</I> |
| 3052 | |
| 3053 | after expansion by |
| 3054 | <B>bash</B>. |
| 3055 | |
| 3056 | If strict compatibility with |
| 3057 | <B>sh</B> |
| 3058 | |
| 3059 | is desired, start |
| 3060 | <B>bash</B> |
| 3061 | |
| 3062 | with the |
| 3063 | <B>+B </B> |
| 3064 | |
| 3065 | option or disable brace expansion with the |
| 3066 | <B>+B</B> |
| 3067 | |
| 3068 | option to the |
| 3069 | <B>set</B> |
| 3070 | |
| 3071 | command (see |
| 3072 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 3073 | |
| 3074 | </FONT> |
| 3075 | below). |
| 3076 | <A NAME="lbBA"> </A> |
| 3077 | <H4>Tilde Expansion</H4> |
| 3078 | |
| 3079 | <P> |
| 3080 | |
| 3081 | If a word begins with an unquoted tilde character (`<B>~</B>'), all of |
| 3082 | the characters preceding the first unquoted slash (or all characters, |
| 3083 | if there is no unquoted slash) are considered a <I>tilde-prefix</I>. |
| 3084 | If none of the characters in the tilde-prefix are quoted, the |
| 3085 | characters in the tilde-prefix following the tilde are treated as a |
| 3086 | possible <I>login name</I>. |
| 3087 | If this login name is the null string, the tilde is replaced with the |
| 3088 | value of the shell parameter |
| 3089 | <FONT SIZE=-1><B>HOME</B>. |
| 3090 | |
| 3091 | </FONT> |
| 3092 | If |
| 3093 | <FONT SIZE=-1><B>HOME</B> |
| 3094 | |
| 3095 | </FONT> |
| 3096 | is unset, the home directory of the user executing the shell is |
| 3097 | substituted instead. |
| 3098 | Otherwise, the tilde-prefix is replaced with the home directory |
| 3099 | associated with the specified login name. |
| 3100 | <P> |
| 3101 | |
| 3102 | If the tilde-prefix is a `~+', the value of the shell variable |
| 3103 | <FONT SIZE=-1><B>PWD</B> |
| 3104 | |
| 3105 | </FONT> |
| 3106 | replaces the tilde-prefix. |
| 3107 | If the tilde-prefix is a `~-', the value of the shell variable |
| 3108 | <FONT SIZE=-1><B>OLDPWD</B>, |
| 3109 | |
| 3110 | </FONT> |
| 3111 | if it is set, is substituted. |
| 3112 | If the characters following the tilde in the tilde-prefix consist |
| 3113 | of a number <I>N</I>, optionally prefixed |
| 3114 | by a `+' or a `-', the tilde-prefix is replaced with the corresponding |
| 3115 | element from the directory stack, as it would be displayed by the |
| 3116 | <B>dirs</B> |
| 3117 | |
| 3118 | builtin invoked with the tilde-prefix as an argument. |
| 3119 | If the characters following the tilde in the tilde-prefix consist of a |
| 3120 | number without a leading `+' or `-', `+' is assumed. |
| 3121 | <P> |
| 3122 | |
| 3123 | If the login name is invalid, or the tilde expansion fails, the word |
| 3124 | is unchanged. |
| 3125 | <P> |
| 3126 | |
| 3127 | Each variable assignment is checked for unquoted tilde-prefixes immediately |
| 3128 | following a |
| 3129 | <B>:</B> |
| 3130 | |
| 3131 | or the first |
| 3132 | <B>=</B>. |
| 3133 | |
| 3134 | In these cases, tilde expansion is also performed. |
| 3135 | Consequently, one may use file names with tildes in assignments to |
| 3136 | <FONT SIZE=-1><B>PATH</B>, |
| 3137 | |
| 3138 | </FONT> |
| 3139 | <FONT SIZE=-1><B>MAILPATH</B>, |
| 3140 | |
| 3141 | </FONT> |
| 3142 | and |
| 3143 | <FONT SIZE=-1><B>CDPATH</B>, |
| 3144 | |
| 3145 | </FONT> |
| 3146 | and the shell assigns the expanded value. |
| 3147 | <A NAME="lbBB"> </A> |
| 3148 | <H4>Parameter Expansion</H4> |
| 3149 | |
| 3150 | <P> |
| 3151 | |
| 3152 | The `<B>$</B>' character introduces parameter expansion, |
| 3153 | command substitution, or arithmetic expansion. The parameter name |
| 3154 | or symbol to be expanded may be enclosed in braces, which |
| 3155 | are optional but serve to protect the variable to be expanded from |
| 3156 | characters immediately following it which could be |
| 3157 | interpreted as part of the name. |
| 3158 | <P> |
| 3159 | |
| 3160 | When braces are used, the matching ending brace is the first `<B>}</B>' |
| 3161 | not escaped by a backslash or within a quoted string, and not within an |
| 3162 | embedded arithmetic expansion, command substitution, or parameter |
| 3163 | expansion. |
| 3164 | <P> |
| 3165 | |
| 3166 | |
| 3167 | <DL COMPACT> |
| 3168 | <DT>${<I>parameter</I>}<DD> |
| 3169 | The value of <I>parameter</I> is substituted. The braces are required |
| 3170 | when |
| 3171 | <I>parameter</I> |
| 3172 | |
| 3173 | is a positional parameter with more than one digit, |
| 3174 | or when |
| 3175 | <I>parameter</I> |
| 3176 | |
| 3177 | is followed by a character which is not to be |
| 3178 | interpreted as part of its name. |
| 3179 | |
| 3180 | </DL> |
| 3181 | <P> |
| 3182 | |
| 3183 | If the first character of <I>parameter</I> is an exclamation point, |
| 3184 | a level of variable indirection is introduced. |
| 3185 | <B>Bash</B> uses the value of the variable formed from the rest of |
| 3186 | <I>parameter</I> as the name of the variable; this variable is then |
| 3187 | expanded and that value is used in the rest of the substitution, rather |
| 3188 | than the value of <I>parameter</I> itself. |
| 3189 | This is known as <I>indirect expansion</I>. |
| 3190 | The exceptions to this are the expansions of ${!<I>prefix</I>*} and |
| 3191 | ${<B>!</B><I>name</I>[<I>@</I>]} described below. |
| 3192 | The exclamation point must immediately follow the left brace in order to |
| 3193 | introduce indirection. |
| 3194 | <P> |
| 3195 | |
| 3196 | In each of the cases below, <I>word</I> is subject to tilde expansion, |
| 3197 | parameter expansion, command substitution, and arithmetic expansion. |
| 3198 | <P> |
| 3199 | |
| 3200 | When not performing substring expansion, using the forms documented below, |
| 3201 | <B>bash</B> tests for a parameter that is unset or null. Omitting the colon |
| 3202 | results in a test only for a parameter that is unset. |
| 3203 | <P> |
| 3204 | |
| 3205 | |
| 3206 | <DL COMPACT> |
| 3207 | <DT>${<I>parameter</I><B>:-</B><I>word</I>}<DD> |
| 3208 | <B>Use Default Values</B>. If |
| 3209 | <I>parameter</I> |
| 3210 | |
| 3211 | is unset or null, the expansion of |
| 3212 | <I>word</I> |
| 3213 | |
| 3214 | is substituted. Otherwise, the value of |
| 3215 | <I>parameter</I> |
| 3216 | |
| 3217 | is substituted. |
| 3218 | <DT>${<I>parameter</I><B>:=</B><I>word</I>}<DD> |
| 3219 | <B>Assign Default Values</B>. |
| 3220 | If |
| 3221 | <I>parameter</I> |
| 3222 | |
| 3223 | is unset or null, the expansion of |
| 3224 | <I>word</I> |
| 3225 | |
| 3226 | is assigned to |
| 3227 | <I>parameter</I>. |
| 3228 | |
| 3229 | The value of |
| 3230 | <I>parameter</I> |
| 3231 | |
| 3232 | is then substituted. Positional parameters and special parameters may |
| 3233 | not be assigned to in this way. |
| 3234 | <DT>${<I>parameter</I><B>:?</B><I>word</I>}<DD> |
| 3235 | <B>Display Error if Null or Unset</B>. |
| 3236 | If |
| 3237 | <I>parameter</I> |
| 3238 | |
| 3239 | is null or unset, the expansion of <I>word</I> (or a message to that effect |
| 3240 | if |
| 3241 | <I>word</I> |
| 3242 | |
| 3243 | is not present) is written to the standard error and the shell, if it |
| 3244 | is not interactive, exits. Otherwise, the value of <I>parameter</I> is |
| 3245 | substituted. |
| 3246 | <DT>${<I>parameter</I><B>:+</B><I>word</I>}<DD> |
| 3247 | <B>Use Alternate Value</B>. |
| 3248 | If |
| 3249 | <I>parameter</I> |
| 3250 | |
| 3251 | is null or unset, nothing is substituted, otherwise the expansion of |
| 3252 | <I>word</I> |
| 3253 | |
| 3254 | is substituted. |
| 3255 | <DT>${<I>parameter</I><B>:</B><I>offset</I>}<DD> |
| 3256 | |
| 3257 | <DT>${<I>parameter</I><B>:</B><I>offset</I><B>:</B><I>length</I>}<DD> |
| 3258 | |
| 3259 | <B>Substring Expansion.</B> |
| 3260 | Expands to up to <I>length</I> characters of <I>parameter</I> |
| 3261 | starting at the character specified by <I>offset</I>. |
| 3262 | If <I>length</I> is omitted, expands to the substring of |
| 3263 | <I>parameter</I> starting at the character specified by <I>offset</I>. |
| 3264 | <I>length</I> and <I>offset</I> are arithmetic expressions (see |
| 3265 | <FONT SIZE=-1><B>ARITHMETIC EVALUATION</B> |
| 3266 | |
| 3267 | </FONT> |
| 3268 | below). |
| 3269 | <I>length</I> must evaluate to a number greater than or equal to zero. |
| 3270 | If <I>offset</I> evaluates to a number less than zero, the value |
| 3271 | is used as an offset from the end of the value of <I>parameter</I>. |
| 3272 | If <I>parameter</I> is <B>@</B>, the result is <I>length</I> positional |
| 3273 | parameters beginning at <I>offset</I>. |
| 3274 | If <I>parameter</I> is an indexed array name subscripted by @ or *, |
| 3275 | the result is the <I>length</I> |
| 3276 | members of the array beginning with ${<I>parameter</I>[<I>offset</I>]}. |
| 3277 | A negative <I>offset</I> is taken relative to one greater than the maximum |
| 3278 | index of the specified array. |
| 3279 | Substring expansion applied to an associative array produces undefined |
| 3280 | results. |
| 3281 | Note that a negative offset must be separated from the colon by at least |
| 3282 | one space to avoid being confused with the :- expansion. |
| 3283 | Substring indexing is zero-based unless the positional parameters |
| 3284 | are used, in which case the indexing starts at 1 by default. |
| 3285 | If <I>offset</I> is 0, and the positional parameters are used, <B>$0</B> is |
| 3286 | prefixed to the list. |
| 3287 | <DT>${<B>!</B><I>prefix</I><B>*</B>}<DD> |
| 3288 | |
| 3289 | <DT>${<B>!</B><I>prefix</I><B>@</B>}<DD> |
| 3290 | |
| 3291 | <B>Names matching prefix.</B> |
| 3292 | Expands to the names of variables whose names begin with <I>prefix</I>, |
| 3293 | separated by the first character of the |
| 3294 | <FONT SIZE=-1><B>IFS</B> |
| 3295 | |
| 3296 | </FONT> |
| 3297 | special variable. |
| 3298 | When <I>@</I> is used and the expansion appears within double quotes, each |
| 3299 | variable name expands to a separate word. |
| 3300 | <DT>${<B>!</B><I>name</I>[<I>@</I>]}<DD> |
| 3301 | |
| 3302 | <DT>${<B>!</B><I>name</I>[<I>*</I>]}<DD> |
| 3303 | |
| 3304 | <B>List of array keys.</B> |
| 3305 | If <I>name</I> is an array variable, expands to the list of array indices |
| 3306 | (keys) assigned in <I>name</I>. |
| 3307 | If <I>name</I> is not an array, expands to 0 if <I>name</I> is set and null |
| 3308 | otherwise. |
| 3309 | When <I>@</I> is used and the expansion appears within double quotes, each |
| 3310 | key expands to a separate word. |
| 3311 | <DT>${<B>#</B><I>parameter</I>}<DD> |
| 3312 | <B>Parameter length.</B> |
| 3313 | The length in characters of the value of <I>parameter</I> is substituted. |
| 3314 | If |
| 3315 | <I>parameter</I> |
| 3316 | |
| 3317 | is |
| 3318 | <B>*</B> |
| 3319 | |
| 3320 | or |
| 3321 | <B>@</B>, |
| 3322 | |
| 3323 | the value substituted is the number of positional parameters. |
| 3324 | If |
| 3325 | <I>parameter</I> |
| 3326 | |
| 3327 | is an array name subscripted by |
| 3328 | <B>*</B> |
| 3329 | |
| 3330 | or |
| 3331 | <B>@</B>, |
| 3332 | |
| 3333 | the value substituted is the number of elements in the array. |
| 3334 | <DT>${<I>parameter</I><B>#</B><I>word</I>}<DD> |
| 3335 | |
| 3336 | <DT>${<I>parameter</I><B>##</B><I>word</I>}<DD> |
| 3337 | |
| 3338 | <B>Remove matching prefix pattern.</B> |
| 3339 | The |
| 3340 | <I>word</I> |
| 3341 | |
| 3342 | is expanded to produce a pattern just as in pathname |
| 3343 | expansion. If the pattern matches the beginning of |
| 3344 | the value of |
| 3345 | <I>parameter</I>, |
| 3346 | |
| 3347 | then the result of the expansion is the expanded value of |
| 3348 | <I>parameter</I> |
| 3349 | |
| 3350 | with the shortest matching pattern (the ``<B>#</B>'' case) or the |
| 3351 | longest matching pattern (the ``<B>##</B>'' case) deleted. |
| 3352 | If |
| 3353 | <I>parameter</I> |
| 3354 | |
| 3355 | is |
| 3356 | <B>@</B> |
| 3357 | |
| 3358 | or |
| 3359 | <B>*</B>, |
| 3360 | |
| 3361 | the pattern removal operation is applied to each positional |
| 3362 | parameter in turn, and the expansion is the resultant list. |
| 3363 | If |
| 3364 | <I>parameter</I> |
| 3365 | |
| 3366 | is an array variable subscripted with |
| 3367 | <B>@</B> |
| 3368 | |
| 3369 | or |
| 3370 | <B>*</B>, |
| 3371 | |
| 3372 | the pattern removal operation is applied to each member of the |
| 3373 | array in turn, and the expansion is the resultant list. |
| 3374 | <DT>${<I>parameter</I><B>%</B><I>word</I>}<DD> |
| 3375 | |
| 3376 | <DT>${<I>parameter</I><B>%%</B><I>word</I>}<DD> |
| 3377 | |
| 3378 | <B>Remove matching suffix pattern.</B> |
| 3379 | The <I>word</I> is expanded to produce a pattern just as in |
| 3380 | pathname expansion. |
| 3381 | If the pattern matches a trailing portion of the expanded value of |
| 3382 | <I>parameter</I>, |
| 3383 | |
| 3384 | then the result of the expansion is the expanded value of |
| 3385 | <I>parameter</I> |
| 3386 | |
| 3387 | with the shortest matching pattern (the ``<B>%</B>'' case) or the |
| 3388 | longest matching pattern (the ``<B>%%</B>'' case) deleted. |
| 3389 | If |
| 3390 | <I>parameter</I> |
| 3391 | |
| 3392 | is |
| 3393 | <B>@</B> |
| 3394 | |
| 3395 | or |
| 3396 | <B>*</B>, |
| 3397 | |
| 3398 | the pattern removal operation is applied to each positional |
| 3399 | parameter in turn, and the expansion is the resultant list. |
| 3400 | If |
| 3401 | <I>parameter</I> |
| 3402 | |
| 3403 | is an array variable subscripted with |
| 3404 | <B>@</B> |
| 3405 | |
| 3406 | or |
| 3407 | <B>*</B>, |
| 3408 | |
| 3409 | the pattern removal operation is applied to each member of the |
| 3410 | array in turn, and the expansion is the resultant list. |
| 3411 | <DT>${<I>parameter</I><B>/</B><I>pattern</I><B>/</B><I>string</I>}<DD> |
| 3412 | <B>Pattern substitution.</B> |
| 3413 | The <I>pattern</I> is expanded to produce a pattern just as in |
| 3414 | pathname expansion. |
| 3415 | <I>Parameter</I> is expanded and the longest match of <I>pattern</I> |
| 3416 | against its value is replaced with <I>string</I>. |
| 3417 | If <I>pattern</I> begins with <B>/</B>, all matches of <I>pattern</I> are |
| 3418 | replaced with <I>string</I>. Normally only the first match is replaced. |
| 3419 | If <I>pattern</I> begins with <B>#</B>, it must match at the beginning |
| 3420 | of the expanded value of <I>parameter</I>. |
| 3421 | If <I>pattern</I> begins with <B>%</B>, it must match at the end |
| 3422 | of the expanded value of <I>parameter</I>. |
| 3423 | If <I>string</I> is null, matches of <I>pattern</I> are deleted |
| 3424 | and the <B>/</B> following <I>pattern</I> may be omitted. |
| 3425 | If |
| 3426 | <I>parameter</I> |
| 3427 | |
| 3428 | is |
| 3429 | <B>@</B> |
| 3430 | |
| 3431 | or |
| 3432 | <B>*</B>, |
| 3433 | |
| 3434 | the substitution operation is applied to each positional |
| 3435 | parameter in turn, and the expansion is the resultant list. |
| 3436 | If |
| 3437 | <I>parameter</I> |
| 3438 | |
| 3439 | is an array variable subscripted with |
| 3440 | <B>@</B> |
| 3441 | |
| 3442 | or |
| 3443 | <B>*</B>, |
| 3444 | |
| 3445 | the substitution operation is applied to each member of the |
| 3446 | array in turn, and the expansion is the resultant list. |
| 3447 | <DT>${<I>parameter</I><B>^</B><I>pattern</I>}<DD> |
| 3448 | |
| 3449 | <DT>${<I>parameter</I><B>^^</B><I>pattern</I>}<DD> |
| 3450 | <DT>${<I>parameter</I><B>,</B><I>pattern</I>}<DD> |
| 3451 | <DT>${<I>parameter</I><B>,,</B><I>pattern</I>}<DD> |
| 3452 | |
| 3453 | <B>Case modification.</B> |
| 3454 | This expansion modifies the case of alphabetic characters in <I>parameter</I>. |
| 3455 | The <I>pattern</I> is expanded to produce a pattern just as in |
| 3456 | pathname expansion. |
| 3457 | The <B>^</B> operator converts lowercase letters matching <I>pattern</I> |
| 3458 | to uppercase; the <B>,</B> operator converts matching uppercase letters |
| 3459 | to lowercase. |
| 3460 | The <B>^^</B> and <B>,,</B> expansions convert each matched character in the |
| 3461 | expanded value; the <B>^</B> and <B>,</B> expansions match and convert only |
| 3462 | the first character in the expanded value.. |
| 3463 | If <I>pattern</I> is omitted, it is treated like a <B>?</B>, which matches |
| 3464 | every character. |
| 3465 | If |
| 3466 | <I>parameter</I> |
| 3467 | |
| 3468 | is |
| 3469 | <B>@</B> |
| 3470 | |
| 3471 | or |
| 3472 | <B>*</B>, |
| 3473 | |
| 3474 | the case modification operation is applied to each positional |
| 3475 | parameter in turn, and the expansion is the resultant list. |
| 3476 | If |
| 3477 | <I>parameter</I> |
| 3478 | |
| 3479 | is an array variable subscripted with |
| 3480 | <B>@</B> |
| 3481 | |
| 3482 | or |
| 3483 | <B>*</B>, |
| 3484 | |
| 3485 | the case modification operation is applied to each member of the |
| 3486 | array in turn, and the expansion is the resultant list. |
| 3487 | </DL> |
| 3488 | <A NAME="lbBC"> </A> |
| 3489 | <H4>Command Substitution</H4> |
| 3490 | |
| 3491 | <P> |
| 3492 | |
| 3493 | <I>Command substitution</I> allows the output of a command to replace |
| 3494 | the command name. There are two forms: |
| 3495 | <P> |
| 3496 | |
| 3497 | <DL COMPACT><DT><DD> |
| 3498 | <P> |
| 3499 | |
| 3500 | <B>$(</B><I>command</I><B>)</B> |
| 3501 | </DL> |
| 3502 | |
| 3503 | or |
| 3504 | <DL COMPACT><DT><DD> |
| 3505 | <B>`</B><I>command</I><B>`</B> |
| 3506 | </DL> |
| 3507 | |
| 3508 | <P> |
| 3509 | |
| 3510 | <B>Bash</B> |
| 3511 | |
| 3512 | performs the expansion by executing <I>command</I> and |
| 3513 | replacing the command substitution with the standard output of the |
| 3514 | command, with any trailing newlines deleted. |
| 3515 | Embedded newlines are not deleted, but they may be removed during |
| 3516 | word splitting. |
| 3517 | The command substitution <B>$(cat </B><I>file</I>) can be replaced by |
| 3518 | the equivalent but faster <B>$(< </B><I>file</I>). |
| 3519 | <P> |
| 3520 | |
| 3521 | When the old-style backquote form of substitution is used, |
| 3522 | backslash retains its literal meaning except when followed by |
| 3523 | <B>$</B>, |
| 3524 | |
| 3525 | <B>`</B>, |
| 3526 | |
| 3527 | or |
| 3528 | <B>\</B>. |
| 3529 | |
| 3530 | The first backquote not preceded by a backslash terminates the |
| 3531 | command substitution. |
| 3532 | When using the $(<I>command</I>) form, all characters between the |
| 3533 | parentheses make up the command; none are treated specially. |
| 3534 | <P> |
| 3535 | |
| 3536 | Command substitutions may be nested. To nest when using the backquoted form, |
| 3537 | escape the inner backquotes with backslashes. |
| 3538 | <P> |
| 3539 | |
| 3540 | If the substitution appears within double quotes, word splitting and |
| 3541 | pathname expansion are not performed on the results. |
| 3542 | <A NAME="lbBD"> </A> |
| 3543 | <H4>Arithmetic Expansion</H4> |
| 3544 | |
| 3545 | <P> |
| 3546 | |
| 3547 | Arithmetic expansion allows the evaluation of an arithmetic expression |
| 3548 | and the substitution of the result. The format for arithmetic expansion is: |
| 3549 | <DL COMPACT><DT><DD> |
| 3550 | <P> |
| 3551 | |
| 3552 | <B>$((</B><I>expression</I><B>))</B> |
| 3553 | </DL> |
| 3554 | |
| 3555 | <P> |
| 3556 | |
| 3557 | The |
| 3558 | <I>expression</I> |
| 3559 | |
| 3560 | is treated as if it were within double quotes, but a double quote |
| 3561 | inside the parentheses is not treated specially. |
| 3562 | All tokens in the expression undergo parameter expansion, string |
| 3563 | expansion, command substitution, and quote removal. |
| 3564 | Arithmetic expansions may be nested. |
| 3565 | <P> |
| 3566 | |
| 3567 | The evaluation is performed according to the rules listed below under |
| 3568 | <FONT SIZE=-1><B>ARITHMETIC EVALUATION</B>. |
| 3569 | |
| 3570 | </FONT> |
| 3571 | If |
| 3572 | <I>expression</I> |
| 3573 | |
| 3574 | is invalid, |
| 3575 | <B>bash</B> |
| 3576 | |
| 3577 | prints a message indicating failure and no substitution occurs. |
| 3578 | <A NAME="lbBE"> </A> |
| 3579 | <H4>Process Substitution</H4> |
| 3580 | |
| 3581 | <P> |
| 3582 | |
| 3583 | <I>Process substitution</I> is supported on systems that support named |
| 3584 | pipes (<I>FIFOs</I>) or the <B>/dev/fd</B> method of naming open files. |
| 3585 | It takes the form of |
| 3586 | <B><(</B><I>list</I><B>)</B> |
| 3587 | or |
| 3588 | <B>>(</B><I>list</I><B>)</B>. |
| 3589 | The process <I>list</I> is run with its input or output connected to a |
| 3590 | <I>FIFO</I> or some file in <B>/dev/fd</B>. The name of this file is |
| 3591 | passed as an argument to the current command as the result of the |
| 3592 | expansion. If the <B>>(</B><I>list</I><B>)</B> form is used, writing to |
| 3593 | the file will provide input for <I>list</I>. If the |
| 3594 | <B><(</B><I>list</I><B>)</B> form is used, the file passed as an |
| 3595 | argument should be read to obtain the output of <I>list</I>. |
| 3596 | <P> |
| 3597 | |
| 3598 | When available, process substitution is performed |
| 3599 | simultaneously with parameter and variable expansion, |
| 3600 | command substitution, |
| 3601 | and arithmetic expansion. |
| 3602 | <A NAME="lbBF"> </A> |
| 3603 | <H4>Word Splitting</H4> |
| 3604 | |
| 3605 | <P> |
| 3606 | |
| 3607 | The shell scans the results of |
| 3608 | parameter expansion, |
| 3609 | command substitution, |
| 3610 | and |
| 3611 | arithmetic expansion |
| 3612 | that did not occur within double quotes for |
| 3613 | <I>word splitting</I>. |
| 3614 | |
| 3615 | <P> |
| 3616 | |
| 3617 | The shell treats each character of |
| 3618 | <FONT SIZE=-1><B>IFS</B> |
| 3619 | |
| 3620 | </FONT> |
| 3621 | as a delimiter, and splits the results of the other |
| 3622 | expansions into words on these characters. If |
| 3623 | <FONT SIZE=-1><B>IFS</B> |
| 3624 | |
| 3625 | </FONT> |
| 3626 | is unset, or its |
| 3627 | value is exactly |
| 3628 | <B><space><tab><newline></B>, |
| 3629 | |
| 3630 | the default, then |
| 3631 | sequences of |
| 3632 | <B><space></B>, |
| 3633 | |
| 3634 | <B><tab></B>, |
| 3635 | |
| 3636 | and |
| 3637 | <B><newline></B> |
| 3638 | |
| 3639 | at the beginning and end of the results of the previous |
| 3640 | expansions are ignored, and |
| 3641 | any sequence of |
| 3642 | <FONT SIZE=-1><B>IFS</B> |
| 3643 | |
| 3644 | </FONT> |
| 3645 | characters not at the beginning or end serves to delimit words. |
| 3646 | If |
| 3647 | <FONT SIZE=-1><B>IFS</B> |
| 3648 | |
| 3649 | </FONT> |
| 3650 | has a value other than the default, then sequences of |
| 3651 | the whitespace characters |
| 3652 | <B>space</B> |
| 3653 | |
| 3654 | and |
| 3655 | <B>tab</B> |
| 3656 | |
| 3657 | are ignored at the beginning and end of the |
| 3658 | word, as long as the whitespace character is in the |
| 3659 | value of |
| 3660 | <FONT SIZE=-1><B>IFS</B> |
| 3661 | |
| 3662 | </FONT> |
| 3663 | (an |
| 3664 | <FONT SIZE=-1><B>IFS</B> |
| 3665 | |
| 3666 | </FONT> |
| 3667 | whitespace character). |
| 3668 | Any character in |
| 3669 | <FONT SIZE=-1><B>IFS</B> |
| 3670 | |
| 3671 | </FONT> |
| 3672 | that is not |
| 3673 | <FONT SIZE=-1><B>IFS</B> |
| 3674 | |
| 3675 | </FONT> |
| 3676 | whitespace, along with any adjacent |
| 3677 | <FONT SIZE=-1><B>IFS</B> |
| 3678 | |
| 3679 | </FONT> |
| 3680 | whitespace characters, delimits a field. |
| 3681 | A sequence of |
| 3682 | <FONT SIZE=-1><B>IFS</B> |
| 3683 | |
| 3684 | </FONT> |
| 3685 | whitespace characters is also treated as a delimiter. |
| 3686 | If the value of |
| 3687 | <FONT SIZE=-1><B>IFS</B> |
| 3688 | |
| 3689 | </FONT> |
| 3690 | is null, no word splitting occurs. |
| 3691 | <P> |
| 3692 | |
| 3693 | Explicit null arguments (<B>""</B> or <B>aqaq</B>) are retained. |
| 3694 | Unquoted implicit null arguments, resulting from the expansion of |
| 3695 | parameters that have no values, are removed. |
| 3696 | If a parameter with no value is expanded within double quotes, a |
| 3697 | null argument results and is retained. |
| 3698 | <P> |
| 3699 | |
| 3700 | Note that if no expansion occurs, no splitting |
| 3701 | is performed. |
| 3702 | <A NAME="lbBG"> </A> |
| 3703 | <H4>Pathname Expansion</H4> |
| 3704 | |
| 3705 | <P> |
| 3706 | |
| 3707 | After word splitting, |
| 3708 | unless the |
| 3709 | <B>-f</B> |
| 3710 | |
| 3711 | option has been set, |
| 3712 | <B>bash</B> |
| 3713 | |
| 3714 | scans each word for the characters |
| 3715 | <B>*</B>, |
| 3716 | |
| 3717 | <B>?</B>, |
| 3718 | |
| 3719 | and |
| 3720 | <B>[</B>. |
| 3721 | |
| 3722 | If one of these characters appears, then the word is |
| 3723 | regarded as a |
| 3724 | <I>pattern</I>, |
| 3725 | |
| 3726 | and replaced with an alphabetically sorted list of |
| 3727 | file names matching the pattern. |
| 3728 | If no matching file names are found, |
| 3729 | and the shell option |
| 3730 | <B>nullglob</B> |
| 3731 | |
| 3732 | is not enabled, the word is left unchanged. |
| 3733 | If the |
| 3734 | <B>nullglob</B> |
| 3735 | |
| 3736 | option is set, and no matches are found, |
| 3737 | the word is removed. |
| 3738 | If the |
| 3739 | <B>failglob</B> |
| 3740 | |
| 3741 | shell option is set, and no matches are found, an error message |
| 3742 | is printed and the command is not executed. |
| 3743 | If the shell option |
| 3744 | <B>nocaseglob</B> |
| 3745 | |
| 3746 | is enabled, the match is performed without regard to the case |
| 3747 | of alphabetic characters. |
| 3748 | When a pattern is used for pathname expansion, |
| 3749 | the character |
| 3750 | <B>``.''</B> |
| 3751 | |
| 3752 | at the start of a name or immediately following a slash |
| 3753 | must be matched explicitly, unless the shell option |
| 3754 | <B>dotglob</B> |
| 3755 | |
| 3756 | is set. |
| 3757 | When matching a pathname, the slash character must always be |
| 3758 | matched explicitly. |
| 3759 | In other cases, the |
| 3760 | <B>``.''</B> |
| 3761 | |
| 3762 | character is not treated specially. |
| 3763 | See the description of |
| 3764 | <B>shopt</B> |
| 3765 | |
| 3766 | below under |
| 3767 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 3768 | |
| 3769 | </FONT> |
| 3770 | for a description of the |
| 3771 | <B>nocaseglob</B>, |
| 3772 | |
| 3773 | <B>nullglob</B>, |
| 3774 | |
| 3775 | <B>failglob</B>, |
| 3776 | |
| 3777 | and |
| 3778 | <B>dotglob</B> |
| 3779 | |
| 3780 | shell options. |
| 3781 | <P> |
| 3782 | |
| 3783 | The |
| 3784 | <FONT SIZE=-1><B>GLOBIGNORE</B> |
| 3785 | |
| 3786 | </FONT> |
| 3787 | shell variable may be used to restrict the set of file names matching a |
| 3788 | <I>pattern</I>. |
| 3789 | |
| 3790 | If |
| 3791 | <FONT SIZE=-1><B>GLOBIGNORE</B> |
| 3792 | |
| 3793 | </FONT> |
| 3794 | is set, each matching file name that also matches one of the patterns in |
| 3795 | <FONT SIZE=-1><B>GLOBIGNORE</B> |
| 3796 | |
| 3797 | </FONT> |
| 3798 | is removed from the list of matches. |
| 3799 | The file names |
| 3800 | <B>``.''</B> |
| 3801 | |
| 3802 | and |
| 3803 | <B>``..''</B> |
| 3804 | |
| 3805 | are always ignored when |
| 3806 | <FONT SIZE=-1><B>GLOBIGNORE</B> |
| 3807 | |
| 3808 | </FONT> |
| 3809 | is set and not null. However, setting |
| 3810 | <FONT SIZE=-1><B>GLOBIGNORE</B> |
| 3811 | |
| 3812 | </FONT> |
| 3813 | to a non-null value has the effect of enabling the |
| 3814 | <B>dotglob</B> |
| 3815 | |
| 3816 | shell option, so all other file names beginning with a |
| 3817 | <B>``.''</B> |
| 3818 | |
| 3819 | will match. |
| 3820 | To get the old behavior of ignoring file names beginning with a |
| 3821 | <B>``.''</B>, |
| 3822 | |
| 3823 | make |
| 3824 | <B>``.*''</B> |
| 3825 | |
| 3826 | one of the patterns in |
| 3827 | <FONT SIZE=-1><B>GLOBIGNORE</B>. |
| 3828 | |
| 3829 | </FONT> |
| 3830 | The |
| 3831 | <B>dotglob</B> |
| 3832 | |
| 3833 | option is disabled when |
| 3834 | <FONT SIZE=-1><B>GLOBIGNORE</B> |
| 3835 | |
| 3836 | </FONT> |
| 3837 | is unset. |
| 3838 | <P> |
| 3839 | |
| 3840 | <B>Pattern Matching</B> |
| 3841 | <P> |
| 3842 | |
| 3843 | Any character that appears in a pattern, other than the special pattern |
| 3844 | characters described below, matches itself. The NUL character may not |
| 3845 | occur in a pattern. A backslash escapes the following character; the |
| 3846 | escaping backslash is discarded when matching. |
| 3847 | The special pattern characters must be quoted if |
| 3848 | they are to be matched literally. |
| 3849 | <P> |
| 3850 | |
| 3851 | The special pattern characters have the following meanings: |
| 3852 | <P> |
| 3853 | |
| 3854 | |
| 3855 | <DL COMPACT> |
| 3856 | <DT><B>*</B> |
| 3857 | |
| 3858 | <DD> |
| 3859 | Matches any string, including the null string. |
| 3860 | When the <B>globstar</B> shell option is enabled, and <B>*</B> is used in |
| 3861 | a filename expansion context, two adjacent <B>*</B>s used as a single |
| 3862 | pattern will match all files and zero or more directories and |
| 3863 | subdirectories. |
| 3864 | If followed by a <B>/</B>, two adjacent <B>*</B>s will match only directories |
| 3865 | and subdirectories. |
| 3866 | <DT><B>?</B> |
| 3867 | |
| 3868 | <DD> |
| 3869 | Matches any single character. |
| 3870 | <DT><B>[...]</B> |
| 3871 | |
| 3872 | <DD> |
| 3873 | Matches any one of the enclosed characters. A pair of characters |
| 3874 | separated by a hyphen denotes a |
| 3875 | <I>range expression</I>; |
| 3876 | any character that sorts between those two characters, inclusive, |
| 3877 | using the current locale's collating sequence and character set, |
| 3878 | is matched. If the first character following the |
| 3879 | <B>[</B> |
| 3880 | |
| 3881 | is a |
| 3882 | <B>!</B> |
| 3883 | |
| 3884 | or a |
| 3885 | <B>^</B> |
| 3886 | |
| 3887 | then any character not enclosed is matched. |
| 3888 | The sorting order of characters in range expressions is determined by |
| 3889 | the current locale and the value of the <B>LC_COLLATE</B> shell variable, |
| 3890 | if set. |
| 3891 | A |
| 3892 | <B>-</B> |
| 3893 | |
| 3894 | may be matched by including it as the first or last character |
| 3895 | in the set. |
| 3896 | A |
| 3897 | <B>]</B> |
| 3898 | |
| 3899 | may be matched by including it as the first character |
| 3900 | in the set. |
| 3901 | <BR> |
| 3902 | |
| 3903 | <P> |
| 3904 | |
| 3905 | |
| 3906 | Within |
| 3907 | <B>[</B> |
| 3908 | |
| 3909 | and |
| 3910 | <B>]</B>, |
| 3911 | |
| 3912 | <I>character classes</I> can be specified using the syntax |
| 3913 | <B>[:</B><I>class</I><B>:]</B>, where <I>class</I> is one of the |
| 3914 | following classes defined in the POSIX standard: |
| 3915 | </DL> |
| 3916 | <P> |
| 3917 | |
| 3918 | <DL COMPACT><DT><DD> |
| 3919 | <B> |
| 3920 | </B> |
| 3921 | |
| 3922 | alnum alpha ascii blank cntrl digit graph lower print punct space upper word xdigit |
| 3923 | <BR> |
| 3924 | |
| 3925 | A character class matches any character belonging to that class. |
| 3926 | The <B>word</B> character class matches letters, digits, and the character _. |
| 3927 | <BR> |
| 3928 | |
| 3929 | <P> |
| 3930 | |
| 3931 | |
| 3932 | Within |
| 3933 | <B>[</B> |
| 3934 | |
| 3935 | and |
| 3936 | <B>]</B>, |
| 3937 | |
| 3938 | an <I>equivalence class</I> can be specified using the syntax |
| 3939 | <B>[=</B><I>c</I><B>=]</B>, which matches all characters with the |
| 3940 | same collation weight (as defined by the current locale) as |
| 3941 | the character <I>c</I>. |
| 3942 | <BR> |
| 3943 | |
| 3944 | <P> |
| 3945 | |
| 3946 | |
| 3947 | Within |
| 3948 | <B>[</B> |
| 3949 | |
| 3950 | and |
| 3951 | <B>]</B>, |
| 3952 | |
| 3953 | the syntax <B>[.</B><I>symbol</I><B>.]</B> matches the collating symbol |
| 3954 | <I>symbol</I>. |
| 3955 | </DL> |
| 3956 | |
| 3957 | |
| 3958 | <P> |
| 3959 | |
| 3960 | If the <B>extglob</B> shell option is enabled using the <B>shopt</B> |
| 3961 | builtin, several extended pattern matching operators are recognized. |
| 3962 | In the following description, a <I>pattern-list</I> is a list of one |
| 3963 | or more patterns separated by a <B>|</B>. |
| 3964 | Composite patterns may be formed using one or more of the following |
| 3965 | sub-patterns: |
| 3966 | <P> |
| 3967 | |
| 3968 | <DL COMPACT><DT><DD> |
| 3969 | <DL COMPACT> |
| 3970 | <DT><B>?(</B><I>pattern-list</I><B>)</B><DD> |
| 3971 | Matches zero or one occurrence of the given patterns |
| 3972 | <DT><B>*(</B><I>pattern-list</I><B>)</B><DD> |
| 3973 | Matches zero or more occurrences of the given patterns |
| 3974 | <DT><B>+(</B><I>pattern-list</I><B>)</B><DD> |
| 3975 | Matches one or more occurrences of the given patterns |
| 3976 | <DT><B>@(</B><I>pattern-list</I><B>)</B><DD> |
| 3977 | Matches one of the given patterns |
| 3978 | <DT><B>!(</B><I>pattern-list</I><B>)</B><DD> |
| 3979 | Matches anything except one of the given patterns |
| 3980 | </DL></DL> |
| 3981 | |
| 3982 | |
| 3983 | <A NAME="lbBH"> </A> |
| 3984 | <H4>Quote Removal</H4> |
| 3985 | |
| 3986 | <P> |
| 3987 | |
| 3988 | After the preceding expansions, all unquoted occurrences of the |
| 3989 | characters |
| 3990 | <B>\</B>, |
| 3991 | |
| 3992 | <B>aq</B>, |
| 3993 | |
| 3994 | and <B>"</B> that did not result from one of the above |
| 3995 | expansions are removed. |
| 3996 | <A NAME="lbBI"> </A> |
| 3997 | <H3>REDIRECTION</H3> |
| 3998 | |
| 3999 | Before a command is executed, its input and output |
| 4000 | may be |
| 4001 | <I>redirected</I> |
| 4002 | |
| 4003 | using a special notation interpreted by the shell. |
| 4004 | Redirection may also be used to open and close files for the |
| 4005 | current shell execution environment. The following redirection |
| 4006 | operators may precede or appear anywhere within a |
| 4007 | <I>simple command</I> |
| 4008 | |
| 4009 | or may follow a |
| 4010 | <I>command</I>. |
| 4011 | |
| 4012 | Redirections are processed in the order they appear, from |
| 4013 | left to right. |
| 4014 | <P> |
| 4015 | |
| 4016 | In the following descriptions, if the file descriptor number is |
| 4017 | omitted, and the first character of the redirection operator is |
| 4018 | <B><</B>, |
| 4019 | |
| 4020 | the redirection refers to the standard input (file descriptor |
| 4021 | 0). If the first character of the redirection operator is |
| 4022 | <B>></B>, |
| 4023 | |
| 4024 | the redirection refers to the standard output (file descriptor |
| 4025 | 1). |
| 4026 | <P> |
| 4027 | |
| 4028 | The word following the redirection operator in the following |
| 4029 | descriptions, unless otherwise noted, is subjected to brace expansion, |
| 4030 | tilde expansion, parameter expansion, command substitution, arithmetic |
| 4031 | expansion, quote removal, pathname expansion, and word splitting. |
| 4032 | If it expands to more than one word, |
| 4033 | <B>bash</B> |
| 4034 | |
| 4035 | reports an error. |
| 4036 | <P> |
| 4037 | |
| 4038 | Note that the order of redirections is significant. For example, |
| 4039 | the command |
| 4040 | <DL COMPACT><DT><DD> |
| 4041 | <P> |
| 4042 | |
| 4043 | ls <B>></B> dirlist 2<B>>&</B>1 |
| 4044 | </DL> |
| 4045 | |
| 4046 | <P> |
| 4047 | |
| 4048 | directs both standard output and standard error to the file |
| 4049 | <I>dirlist</I>, |
| 4050 | |
| 4051 | while the command |
| 4052 | <DL COMPACT><DT><DD> |
| 4053 | <P> |
| 4054 | |
| 4055 | ls 2<B>>&</B>1 <B>></B> dirlist |
| 4056 | </DL> |
| 4057 | |
| 4058 | <P> |
| 4059 | |
| 4060 | directs only the standard output to file |
| 4061 | <I>dirlist</I>, |
| 4062 | |
| 4063 | because the standard error was duplicated as standard output |
| 4064 | before the standard output was redirected to |
| 4065 | <I>dirlist</I>. |
| 4066 | |
| 4067 | <P> |
| 4068 | |
| 4069 | <B>Bash</B> handles several filenames specially when they are used in |
| 4070 | redirections, as described in the following table: |
| 4071 | <DL COMPACT><DT><DD> |
| 4072 | <P> |
| 4073 | |
| 4074 | |
| 4075 | <DL COMPACT> |
| 4076 | <DT><B>/dev/fd/</B><I>fd</I> |
| 4077 | |
| 4078 | <DD> |
| 4079 | If <I>fd</I> is a valid integer, file descriptor <I>fd</I> is duplicated. |
| 4080 | <DT><B>/dev/stdin</B> |
| 4081 | |
| 4082 | <DD> |
| 4083 | File descriptor 0 is duplicated. |
| 4084 | <DT><B>/dev/stdout</B> |
| 4085 | |
| 4086 | <DD> |
| 4087 | File descriptor 1 is duplicated. |
| 4088 | <DT><B>/dev/stderr</B> |
| 4089 | |
| 4090 | <DD> |
| 4091 | File descriptor 2 is duplicated. |
| 4092 | <DT><B>/dev/tcp/</B><I>host</I>/<I>port</I> |
| 4093 | |
| 4094 | <DD> |
| 4095 | If <I>host</I> is a valid hostname or Internet address, and <I>port</I> |
| 4096 | is an integer port number or service name, <B>bash</B> attempts to open |
| 4097 | a TCP connection to the corresponding socket. |
| 4098 | <DT><B>/dev/udp/</B><I>host</I>/<I>port</I> |
| 4099 | |
| 4100 | <DD> |
| 4101 | If <I>host</I> is a valid hostname or Internet address, and <I>port</I> |
| 4102 | is an integer port number or service name, <B>bash</B> attempts to open |
| 4103 | a UDP connection to the corresponding socket. |
| 4104 | |
| 4105 | </DL></DL> |
| 4106 | |
| 4107 | <P> |
| 4108 | |
| 4109 | A failure to open or create a file causes the redirection to fail. |
| 4110 | <P> |
| 4111 | |
| 4112 | Redirections using file descriptors greater than 9 should be used with |
| 4113 | care, as they may conflict with file descriptors the shell uses |
| 4114 | internally. |
| 4115 | <A NAME="lbBJ"> </A> |
| 4116 | <H4>Redirecting Input</H4> |
| 4117 | |
| 4118 | <P> |
| 4119 | |
| 4120 | Redirection of input causes the file whose name results from |
| 4121 | the expansion of |
| 4122 | <I>word</I> |
| 4123 | |
| 4124 | to be opened for reading on file descriptor |
| 4125 | <I>n</I>, |
| 4126 | |
| 4127 | or the standard input (file descriptor 0) if |
| 4128 | <I>n</I> |
| 4129 | |
| 4130 | is not specified. |
| 4131 | <P> |
| 4132 | |
| 4133 | The general format for redirecting input is: |
| 4134 | <DL COMPACT><DT><DD> |
| 4135 | <P> |
| 4136 | |
| 4137 | [<I>n</I>]<B><</B><I>word</I> |
| 4138 | </DL> |
| 4139 | |
| 4140 | <A NAME="lbBK"> </A> |
| 4141 | <H4>Redirecting Output</H4> |
| 4142 | |
| 4143 | <P> |
| 4144 | |
| 4145 | Redirection of output causes the file whose name results from |
| 4146 | the expansion of |
| 4147 | <I>word</I> |
| 4148 | |
| 4149 | to be opened for writing on file descriptor |
| 4150 | <I>n</I>, |
| 4151 | |
| 4152 | or the standard output (file descriptor 1) if |
| 4153 | <I>n</I> |
| 4154 | |
| 4155 | is not specified. If the file does not exist it is created; |
| 4156 | if it does exist it is truncated to zero size. |
| 4157 | <P> |
| 4158 | |
| 4159 | The general format for redirecting output is: |
| 4160 | <DL COMPACT><DT><DD> |
| 4161 | <P> |
| 4162 | |
| 4163 | [<I>n</I>]<B>></B><I>word</I> |
| 4164 | </DL> |
| 4165 | |
| 4166 | <P> |
| 4167 | |
| 4168 | If the redirection operator is |
| 4169 | <B>></B>, |
| 4170 | |
| 4171 | and the |
| 4172 | <B>noclobber</B> |
| 4173 | |
| 4174 | option to the |
| 4175 | <B>set</B> |
| 4176 | |
| 4177 | builtin has been enabled, the redirection will fail if the file |
| 4178 | whose name results from the expansion of <I>word</I> exists and is |
| 4179 | a regular file. |
| 4180 | If the redirection operator is |
| 4181 | <B>>|</B>, |
| 4182 | |
| 4183 | or the redirection operator is |
| 4184 | <B>></B> |
| 4185 | |
| 4186 | and the |
| 4187 | <B>noclobber</B> |
| 4188 | |
| 4189 | option to the |
| 4190 | <B>set</B> |
| 4191 | |
| 4192 | builtin command is not enabled, the redirection is attempted even |
| 4193 | if the file named by <I>word</I> exists. |
| 4194 | <A NAME="lbBL"> </A> |
| 4195 | <H4>Appending Redirected Output</H4> |
| 4196 | |
| 4197 | <P> |
| 4198 | |
| 4199 | Redirection of output in this fashion |
| 4200 | causes the file whose name results from |
| 4201 | the expansion of |
| 4202 | <I>word</I> |
| 4203 | |
| 4204 | to be opened for appending on file descriptor |
| 4205 | <I>n</I>, |
| 4206 | |
| 4207 | or the standard output (file descriptor 1) if |
| 4208 | <I>n</I> |
| 4209 | |
| 4210 | is not specified. If the file does not exist it is created. |
| 4211 | <P> |
| 4212 | |
| 4213 | The general format for appending output is: |
| 4214 | <DL COMPACT><DT><DD> |
| 4215 | <P> |
| 4216 | |
| 4217 | [<I>n</I>]<B>>></B><I>word</I> |
| 4218 | </DL> |
| 4219 | |
| 4220 | <P> |
| 4221 | |
| 4222 | <A NAME="lbBM"> </A> |
| 4223 | <H4>Redirecting Standard Output and Standard Error</H4> |
| 4224 | |
| 4225 | <P> |
| 4226 | |
| 4227 | This construct allows both the |
| 4228 | standard output (file descriptor 1) and |
| 4229 | the standard error output (file descriptor 2) |
| 4230 | to be redirected to the file whose name is the |
| 4231 | expansion of |
| 4232 | <I>word</I>. |
| 4233 | |
| 4234 | <P> |
| 4235 | |
| 4236 | There are two formats for redirecting standard output and |
| 4237 | standard error: |
| 4238 | <DL COMPACT><DT><DD> |
| 4239 | <P> |
| 4240 | |
| 4241 | <B>&></B><I>word</I> |
| 4242 | </DL> |
| 4243 | |
| 4244 | and |
| 4245 | <DL COMPACT><DT><DD> |
| 4246 | <B>>&</B><I>word</I> |
| 4247 | </DL> |
| 4248 | |
| 4249 | <P> |
| 4250 | |
| 4251 | Of the two forms, the first is preferred. |
| 4252 | This is semantically equivalent to |
| 4253 | <DL COMPACT><DT><DD> |
| 4254 | <P> |
| 4255 | |
| 4256 | <B>></B><I>word</I> 2<B>>&</B>1 |
| 4257 | </DL> |
| 4258 | |
| 4259 | <P> |
| 4260 | |
| 4261 | <A NAME="lbBN"> </A> |
| 4262 | <H4>Appending Standard Output and Standard Error</H4> |
| 4263 | |
| 4264 | <P> |
| 4265 | |
| 4266 | This construct allows both the |
| 4267 | standard output (file descriptor 1) and |
| 4268 | the standard error output (file descriptor 2) |
| 4269 | to be appended to the file whose name is the |
| 4270 | expansion of |
| 4271 | <I>word</I>. |
| 4272 | |
| 4273 | <P> |
| 4274 | |
| 4275 | The format for appending standard output and standard error is: |
| 4276 | <DL COMPACT><DT><DD> |
| 4277 | <P> |
| 4278 | |
| 4279 | <B>&>></B><I>word</I> |
| 4280 | </DL> |
| 4281 | |
| 4282 | <P> |
| 4283 | |
| 4284 | This is semantically equivalent to |
| 4285 | <DL COMPACT><DT><DD> |
| 4286 | <P> |
| 4287 | |
| 4288 | <B>>></B><I>word</I> 2<B>>&</B>1 |
| 4289 | </DL> |
| 4290 | |
| 4291 | <A NAME="lbBO"> </A> |
| 4292 | <H4>Here Documents</H4> |
| 4293 | |
| 4294 | <P> |
| 4295 | |
| 4296 | This type of redirection instructs the shell to read input from the |
| 4297 | current source until a line containing only |
| 4298 | <I>delimiter</I> |
| 4299 | |
| 4300 | (with no trailing blanks) |
| 4301 | is seen. All of |
| 4302 | the lines read up to that point are then used as the standard |
| 4303 | input for a command. |
| 4304 | <P> |
| 4305 | |
| 4306 | The format of here-documents is: |
| 4307 | <DL COMPACT><DT><DD> |
| 4308 | <P> |
| 4309 | |
| 4310 | <PRE> |
| 4311 | <B><<</B>[<B>-</B>]<I>word</I> |
| 4312 | <I>here-document</I> |
| 4313 | <I>delimiter</I> |
| 4314 | </PRE> |
| 4315 | |
| 4316 | </DL> |
| 4317 | |
| 4318 | <P> |
| 4319 | |
| 4320 | No parameter expansion, command substitution, arithmetic expansion, |
| 4321 | or pathname expansion is performed on |
| 4322 | <I>word</I>. |
| 4323 | |
| 4324 | If any characters in |
| 4325 | <I>word</I> |
| 4326 | |
| 4327 | are quoted, the |
| 4328 | <I>delimiter</I> |
| 4329 | |
| 4330 | is the result of quote removal on |
| 4331 | <I>word</I>, |
| 4332 | |
| 4333 | and the lines in the here-document are not expanded. |
| 4334 | If <I>word</I> is unquoted, |
| 4335 | all lines of the here-document are subjected to parameter expansion, |
| 4336 | command substitution, and arithmetic expansion. In the latter |
| 4337 | case, the character sequence |
| 4338 | <B>\<newline></B> |
| 4339 | |
| 4340 | is ignored, and |
| 4341 | <B>\</B> |
| 4342 | |
| 4343 | must be used to quote the characters |
| 4344 | <B>\</B>, |
| 4345 | |
| 4346 | <B>$</B>, |
| 4347 | |
| 4348 | and |
| 4349 | <B>`</B>. |
| 4350 | |
| 4351 | <P> |
| 4352 | |
| 4353 | If the redirection operator is |
| 4354 | <B><<-</B>, |
| 4355 | |
| 4356 | then all leading tab characters are stripped from input lines and the |
| 4357 | line containing |
| 4358 | <I>delimiter</I>. |
| 4359 | |
| 4360 | This allows |
| 4361 | here-documents within shell scripts to be indented in a |
| 4362 | natural fashion. |
| 4363 | <A NAME="lbBP"> </A> |
| 4364 | <H4>Here Strings</H4> |
| 4365 | |
| 4366 | A variant of here documents, the format is: |
| 4367 | <DL COMPACT><DT><DD> |
| 4368 | <P> |
| 4369 | |
| 4370 | <PRE> |
| 4371 | <B><<<</B><I>word</I> |
| 4372 | </PRE> |
| 4373 | |
| 4374 | </DL> |
| 4375 | |
| 4376 | <P> |
| 4377 | |
| 4378 | The <I>word</I> is expanded and supplied to the command on its standard |
| 4379 | input. |
| 4380 | <A NAME="lbBQ"> </A> |
| 4381 | <H4>Duplicating File Descriptors</H4> |
| 4382 | |
| 4383 | <P> |
| 4384 | |
| 4385 | The redirection operator |
| 4386 | <DL COMPACT><DT><DD> |
| 4387 | <P> |
| 4388 | |
| 4389 | [<I>n</I>]<B><&</B><I>word</I> |
| 4390 | </DL> |
| 4391 | |
| 4392 | <P> |
| 4393 | |
| 4394 | is used to duplicate input file descriptors. |
| 4395 | If |
| 4396 | <I>word</I> |
| 4397 | |
| 4398 | expands to one or more digits, the file descriptor denoted by |
| 4399 | <I>n</I> |
| 4400 | |
| 4401 | is made to be a copy of that file descriptor. |
| 4402 | If the digits in |
| 4403 | <I>word</I> |
| 4404 | |
| 4405 | do not specify a file descriptor open for input, a redirection error occurs. |
| 4406 | If |
| 4407 | <I>word</I> |
| 4408 | |
| 4409 | evaluates to |
| 4410 | <B>-</B>, |
| 4411 | |
| 4412 | file descriptor |
| 4413 | <I>n</I> |
| 4414 | |
| 4415 | is closed. If |
| 4416 | <I>n</I> |
| 4417 | |
| 4418 | is not specified, the standard input (file descriptor 0) is used. |
| 4419 | <P> |
| 4420 | |
| 4421 | The operator |
| 4422 | <DL COMPACT><DT><DD> |
| 4423 | <P> |
| 4424 | |
| 4425 | [<I>n</I>]<B>>&</B><I>word</I> |
| 4426 | </DL> |
| 4427 | |
| 4428 | <P> |
| 4429 | |
| 4430 | is used similarly to duplicate output file descriptors. If |
| 4431 | <I>n</I> |
| 4432 | |
| 4433 | is not specified, the standard output (file descriptor 1) is used. |
| 4434 | If the digits in |
| 4435 | <I>word</I> |
| 4436 | |
| 4437 | do not specify a file descriptor open for output, a redirection error occurs. |
| 4438 | As a special case, if <I>n</I> is omitted, and <I>word</I> does not |
| 4439 | expand to one or more digits, the standard output and standard |
| 4440 | error are redirected as described previously. |
| 4441 | <A NAME="lbBR"> </A> |
| 4442 | <H4>Moving File Descriptors</H4> |
| 4443 | |
| 4444 | <P> |
| 4445 | |
| 4446 | The redirection operator |
| 4447 | <DL COMPACT><DT><DD> |
| 4448 | <P> |
| 4449 | |
| 4450 | [<I>n</I>]<B><&</B><I>digit</I><B>-</B> |
| 4451 | </DL> |
| 4452 | |
| 4453 | <P> |
| 4454 | |
| 4455 | moves the file descriptor <I>digit</I> to file descriptor |
| 4456 | <I>n</I>, |
| 4457 | |
| 4458 | or the standard input (file descriptor 0) if <I>n</I> is not specified. |
| 4459 | <I>digit</I> is closed after being duplicated to <I>n</I>. |
| 4460 | <P> |
| 4461 | |
| 4462 | Similarly, the redirection operator |
| 4463 | <DL COMPACT><DT><DD> |
| 4464 | <P> |
| 4465 | |
| 4466 | [<I>n</I>]<B>>&</B><I>digit</I><B>-</B> |
| 4467 | </DL> |
| 4468 | |
| 4469 | <P> |
| 4470 | |
| 4471 | moves the file descriptor <I>digit</I> to file descriptor |
| 4472 | <I>n</I>, |
| 4473 | |
| 4474 | or the standard output (file descriptor 1) if <I>n</I> is not specified. |
| 4475 | <A NAME="lbBS"> </A> |
| 4476 | <H4>Opening File Descriptors for Reading and Writing</H4> |
| 4477 | |
| 4478 | <P> |
| 4479 | |
| 4480 | The redirection operator |
| 4481 | <DL COMPACT><DT><DD> |
| 4482 | <P> |
| 4483 | |
| 4484 | [<I>n</I>]<B><></B><I>word</I> |
| 4485 | </DL> |
| 4486 | |
| 4487 | <P> |
| 4488 | |
| 4489 | causes the file whose name is the expansion of |
| 4490 | <I>word</I> |
| 4491 | |
| 4492 | to be opened for both reading and writing on file descriptor |
| 4493 | <I>n</I>, |
| 4494 | |
| 4495 | or on file descriptor 0 if |
| 4496 | <I>n</I> |
| 4497 | |
| 4498 | is not specified. If the file does not exist, it is created. |
| 4499 | <A NAME="lbBT"> </A> |
| 4500 | <H3>ALIASES</H3> |
| 4501 | |
| 4502 | <I>Aliases</I> allow a string to be substituted for a word when it is used |
| 4503 | as the first word of a simple command. |
| 4504 | The shell maintains a list of aliases that may be set and unset with the |
| 4505 | <B>alias</B> |
| 4506 | |
| 4507 | and |
| 4508 | <B>unalias</B> |
| 4509 | |
| 4510 | builtin commands (see |
| 4511 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 4512 | |
| 4513 | </FONT> |
| 4514 | below). |
| 4515 | The first word of each simple command, if unquoted, |
| 4516 | is checked to see if it has an |
| 4517 | alias. If so, that word is replaced by the text of the alias. |
| 4518 | The characters <B>/</B>, <B>$</B>, <B>`</B>, and <B>=</B> and |
| 4519 | any of the shell <I>metacharacters</I> or quoting characters |
| 4520 | listed above may not appear in an alias name. |
| 4521 | The replacement text may contain any valid shell input, |
| 4522 | including shell metacharacters. |
| 4523 | The first word of the replacement text is tested |
| 4524 | for aliases, but a word that is identical to an alias being expanded |
| 4525 | is not expanded a second time. |
| 4526 | This means that one may alias |
| 4527 | <B>ls</B> |
| 4528 | |
| 4529 | to |
| 4530 | <B>ls -F</B>, |
| 4531 | |
| 4532 | for instance, and |
| 4533 | <B>bash</B> |
| 4534 | |
| 4535 | does not try to recursively expand the replacement text. |
| 4536 | If the last character of the alias value is a |
| 4537 | <I>blank</I>, |
| 4538 | |
| 4539 | then the next command |
| 4540 | word following the alias is also checked for alias expansion. |
| 4541 | <P> |
| 4542 | |
| 4543 | Aliases are created and listed with the |
| 4544 | <B>alias</B> |
| 4545 | |
| 4546 | command, and removed with the |
| 4547 | <B>unalias</B> |
| 4548 | |
| 4549 | command. |
| 4550 | <P> |
| 4551 | |
| 4552 | There is no mechanism for using arguments in the replacement text. |
| 4553 | If arguments are needed, a shell function should be used (see |
| 4554 | <FONT SIZE=-1><B>FUNCTIONS</B> |
| 4555 | |
| 4556 | </FONT> |
| 4557 | below). |
| 4558 | <P> |
| 4559 | |
| 4560 | Aliases are not expanded when the shell is not interactive, unless |
| 4561 | the |
| 4562 | <B>expand_aliases</B> |
| 4563 | |
| 4564 | shell option is set using |
| 4565 | <B>shopt</B> |
| 4566 | |
| 4567 | (see the description of |
| 4568 | <B>shopt</B> |
| 4569 | |
| 4570 | under |
| 4571 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B></FONT> |
| 4572 | below). |
| 4573 | <P> |
| 4574 | |
| 4575 | The rules concerning the definition and use of aliases are |
| 4576 | somewhat confusing. |
| 4577 | <B>Bash</B> |
| 4578 | |
| 4579 | always reads at least one complete line |
| 4580 | of input before executing any |
| 4581 | of the commands on that line. Aliases are expanded when a |
| 4582 | command is read, not when it is executed. Therefore, an |
| 4583 | alias definition appearing on the same line as another |
| 4584 | command does not take effect until the next line of input is read. |
| 4585 | The commands following the alias definition |
| 4586 | on that line are not affected by the new alias. |
| 4587 | This behavior is also an issue when functions are executed. |
| 4588 | Aliases are expanded when a function definition is read, |
| 4589 | not when the function is executed, because a function definition |
| 4590 | is itself a compound command. As a consequence, aliases |
| 4591 | defined in a function are not available until after that |
| 4592 | function is executed. To be safe, always put |
| 4593 | alias definitions on a separate line, and do not use |
| 4594 | <B>alias</B> |
| 4595 | |
| 4596 | in compound commands. |
| 4597 | <P> |
| 4598 | |
| 4599 | For almost every purpose, aliases are superseded by |
| 4600 | shell functions. |
| 4601 | <A NAME="lbBU"> </A> |
| 4602 | <H3>FUNCTIONS</H3> |
| 4603 | |
| 4604 | A shell function, defined as described above under |
| 4605 | <FONT SIZE=-1><B>SHELL GRAMMAR</B>, |
| 4606 | |
| 4607 | </FONT> |
| 4608 | stores a series of commands for later execution. |
| 4609 | When the name of a shell function is used as a simple command name, |
| 4610 | the list of commands associated with that function name is executed. |
| 4611 | Functions are executed in the context of the |
| 4612 | current shell; no new process is created to interpret |
| 4613 | them (contrast this with the execution of a shell script). |
| 4614 | When a function is executed, the arguments to the |
| 4615 | function become the positional parameters |
| 4616 | during its execution. |
| 4617 | The special parameter |
| 4618 | <B>#</B> |
| 4619 | |
| 4620 | is updated to reflect the change. Special parameter 0 |
| 4621 | is unchanged. |
| 4622 | The first element of the |
| 4623 | <FONT SIZE=-1><B>FUNCNAME</B> |
| 4624 | |
| 4625 | </FONT> |
| 4626 | variable is set to the name of the function while the function |
| 4627 | is executing. |
| 4628 | All other aspects of the shell execution |
| 4629 | environment are identical between a function and its caller |
| 4630 | with the exception that the |
| 4631 | <FONT SIZE=-1><B>DEBUG</B> |
| 4632 | |
| 4633 | </FONT> |
| 4634 | and |
| 4635 | <B>RETURN</B> |
| 4636 | |
| 4637 | traps (see the description of the |
| 4638 | <B>trap</B> |
| 4639 | |
| 4640 | builtin under |
| 4641 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 4642 | |
| 4643 | </FONT> |
| 4644 | below) are not inherited unless the function has been given the |
| 4645 | <B>trace</B> attribute (see the description of the |
| 4646 | <FONT SIZE=-1><B>declare</B> |
| 4647 | |
| 4648 | </FONT> |
| 4649 | builtin below) or the |
| 4650 | <B>-o functrace</B> shell option has been enabled with |
| 4651 | the <B>set</B> builtin |
| 4652 | (in which case all functions inherit the <B>DEBUG</B> and <B>RETURN</B> traps). |
| 4653 | <P> |
| 4654 | |
| 4655 | Variables local to the function may be declared with the |
| 4656 | <B>local</B> |
| 4657 | |
| 4658 | builtin command. Ordinarily, variables and their values |
| 4659 | are shared between the function and its caller. |
| 4660 | <P> |
| 4661 | |
| 4662 | If the builtin command |
| 4663 | <B>return</B> |
| 4664 | |
| 4665 | is executed in a function, the function completes and |
| 4666 | execution resumes with the next command after the function |
| 4667 | call. |
| 4668 | Any command associated with the <B>RETURN</B> trap is executed |
| 4669 | before execution resumes. |
| 4670 | When a function completes, the values of the |
| 4671 | positional parameters and the special parameter |
| 4672 | <B>#</B> |
| 4673 | |
| 4674 | are restored to the values they had prior to the function's |
| 4675 | execution. |
| 4676 | <P> |
| 4677 | |
| 4678 | Function names and definitions may be listed with the |
| 4679 | <B>-f</B> |
| 4680 | |
| 4681 | option to the |
| 4682 | <B>declare</B> |
| 4683 | |
| 4684 | or |
| 4685 | <B>typeset</B> |
| 4686 | |
| 4687 | builtin commands. The |
| 4688 | <B>-F</B> |
| 4689 | |
| 4690 | option to |
| 4691 | <B>declare</B> |
| 4692 | |
| 4693 | or |
| 4694 | <B>typeset</B> |
| 4695 | |
| 4696 | will list the function names only |
| 4697 | (and optionally the source file and line number, if the <B>extdebug</B> |
| 4698 | shell option is enabled). |
| 4699 | Functions may be exported so that subshells |
| 4700 | automatically have them defined with the |
| 4701 | <B>-f</B> |
| 4702 | |
| 4703 | option to the |
| 4704 | <B>export</B> |
| 4705 | |
| 4706 | builtin. |
| 4707 | A function definition may be deleted using the <B>-f</B> option to |
| 4708 | the |
| 4709 | <B>unset</B> |
| 4710 | |
| 4711 | builtin. |
| 4712 | Note that shell functions and variables with the same name may result |
| 4713 | in multiple identically-named entries in the environment passed to the |
| 4714 | shell's children. |
| 4715 | Care should be taken in cases where this may cause a problem. |
| 4716 | <P> |
| 4717 | |
| 4718 | Functions may be recursive. No limit is imposed on the number |
| 4719 | of recursive calls. |
| 4720 | <A NAME="lbBV"> </A> |
| 4721 | <H3>ARITHMETIC EVALUATION</H3> |
| 4722 | |
| 4723 | The shell allows arithmetic expressions to be evaluated, under |
| 4724 | certain circumstances (see the <B>let</B> and <B>declare</B> builtin |
| 4725 | commands and <B>Arithmetic Expansion</B>). |
| 4726 | Evaluation is done in fixed-width integers with no check for overflow, |
| 4727 | though division by 0 is trapped and flagged as an error. |
| 4728 | The operators and their precedence, associativity, and values |
| 4729 | are the same as in the C language. |
| 4730 | The following list of operators is grouped into levels of |
| 4731 | equal-precedence operators. |
| 4732 | The levels are listed in order of decreasing precedence. |
| 4733 | <P> |
| 4734 | |
| 4735 | |
| 4736 | <DL COMPACT> |
| 4737 | <DT><B></B><I>id</I>++ <I>id</I>-- |
| 4738 | |
| 4739 | <DD> |
| 4740 | variable post-increment and post-decrement |
| 4741 | <DT><B>++</B><I>id</I> --<I>id</I> |
| 4742 | |
| 4743 | <DD> |
| 4744 | variable pre-increment and pre-decrement |
| 4745 | <DT><B>- +</B> |
| 4746 | |
| 4747 | <DD> |
| 4748 | unary minus and plus |
| 4749 | <DT><B>! ~</B> |
| 4750 | |
| 4751 | <DD> |
| 4752 | logical and bitwise negation |
| 4753 | <DT><B>**</B> |
| 4754 | |
| 4755 | <DD> |
| 4756 | exponentiation |
| 4757 | <DT><B>* / %</B> |
| 4758 | |
| 4759 | <DD> |
| 4760 | multiplication, division, remainder |
| 4761 | <DT><B>+ -</B> |
| 4762 | |
| 4763 | <DD> |
| 4764 | addition, subtraction |
| 4765 | <DT><B><< >></B> |
| 4766 | |
| 4767 | <DD> |
| 4768 | left and right bitwise shifts |
| 4769 | <DT><B><= >= < ></B> |
| 4770 | |
| 4771 | <DD> |
| 4772 | comparison |
| 4773 | <DT><B>== !=</B> |
| 4774 | |
| 4775 | <DD> |
| 4776 | equality and inequality |
| 4777 | <DT><B>&</B> |
| 4778 | |
| 4779 | <DD> |
| 4780 | bitwise AND |
| 4781 | <DT><B>^</B> |
| 4782 | |
| 4783 | <DD> |
| 4784 | bitwise exclusive OR |
| 4785 | <DT><B>|</B> |
| 4786 | |
| 4787 | <DD> |
| 4788 | bitwise OR |
| 4789 | <DT><B>&&</B> |
| 4790 | |
| 4791 | <DD> |
| 4792 | logical AND |
| 4793 | <DT><B>||</B> |
| 4794 | |
| 4795 | <DD> |
| 4796 | logical OR |
| 4797 | <DT><B></B><I>expr</I>?<I>expr</I>:<I>expr</I> |
| 4798 | |
| 4799 | <DD> |
| 4800 | conditional operator |
| 4801 | <DT><B>= *= /= %= += -= <<= >>= &= ^= |=</B> |
| 4802 | |
| 4803 | <DD> |
| 4804 | assignment |
| 4805 | <DT><B></B><I>expr1</I> , <I>expr2</I> |
| 4806 | |
| 4807 | <DD> |
| 4808 | comma |
| 4809 | |
| 4810 | </DL> |
| 4811 | <P> |
| 4812 | |
| 4813 | Shell variables are allowed as operands; parameter expansion is |
| 4814 | performed before the expression is evaluated. |
| 4815 | Within an expression, shell variables may also be referenced by name |
| 4816 | without using the parameter expansion syntax. |
| 4817 | A shell variable that is null or unset evaluates to 0 when referenced |
| 4818 | by name without using the parameter expansion syntax. |
| 4819 | The value of a variable is evaluated as an arithmetic expression |
| 4820 | when it is referenced, or when a variable which has been given the |
| 4821 | <I>integer</I> attribute using <B>declare -i</B> is assigned a value. |
| 4822 | A null value evaluates to 0. |
| 4823 | A shell variable need not have its integer attribute |
| 4824 | turned on to be used in an expression. |
| 4825 | <P> |
| 4826 | |
| 4827 | Constants with a leading 0 are interpreted as octal numbers. |
| 4828 | A leading 0x or 0X denotes hexadecimal. |
| 4829 | Otherwise, numbers take the form [<I>base#</I>]n, where <I>base</I> |
| 4830 | is a decimal number between 2 and 64 representing the arithmetic |
| 4831 | base, and <I>n</I> is a number in that base. |
| 4832 | If <I>base#</I> is omitted, then base 10 is used. |
| 4833 | The digits greater than 9 are represented by the lowercase letters, |
| 4834 | the uppercase letters, @, and _, in that order. |
| 4835 | If <I>base</I> is less than or equal to 36, lowercase and uppercase |
| 4836 | letters may be used interchangeably to represent numbers between 10 |
| 4837 | and 35. |
| 4838 | <P> |
| 4839 | |
| 4840 | Operators are evaluated in order of precedence. Sub-expressions in |
| 4841 | parentheses are evaluated first and may override the precedence |
| 4842 | rules above. |
| 4843 | <A NAME="lbBW"> </A> |
| 4844 | <H3>CONDITIONAL EXPRESSIONS</H3> |
| 4845 | |
| 4846 | Conditional expressions are used by the <B>[[</B> compound command and |
| 4847 | the <B>test</B> and <B>[</B> builtin commands to test file attributes |
| 4848 | and perform string and arithmetic comparisons. |
| 4849 | Expressions are formed from the following unary or binary primaries. |
| 4850 | If any <I>file</I> argument to one of the primaries is of the form |
| 4851 | <I>/dev/fd/n</I>, then file descriptor <I>n</I> is checked. |
| 4852 | If the <I>file</I> argument to one of the primaries is one of |
| 4853 | <I>/dev/stdin</I>, <I>/dev/stdout</I>, or <I>/dev/stderr</I>, file |
| 4854 | descriptor 0, 1, or 2, respectively, is checked. |
| 4855 | <P> |
| 4856 | |
| 4857 | Unless otherwise specified, primaries that operate on files follow symbolic |
| 4858 | links and operate on the target of the link, rather than the link itself. |
| 4859 | <P> |
| 4860 | |
| 4861 | <DL COMPACT> |
| 4862 | <DT><B>-a </B><I>file</I> |
| 4863 | |
| 4864 | <DD> |
| 4865 | True if <I>file</I> exists. |
| 4866 | <DT><B>-b </B><I>file</I> |
| 4867 | |
| 4868 | <DD> |
| 4869 | True if <I>file</I> exists and is a block special file. |
| 4870 | <DT><B>-c </B><I>file</I> |
| 4871 | |
| 4872 | <DD> |
| 4873 | True if <I>file</I> exists and is a character special file. |
| 4874 | <DT><B>-d </B><I>file</I> |
| 4875 | |
| 4876 | <DD> |
| 4877 | True if <I>file</I> exists and is a directory. |
| 4878 | <DT><B>-e </B><I>file</I> |
| 4879 | |
| 4880 | <DD> |
| 4881 | True if <I>file</I> exists. |
| 4882 | <DT><B>-f </B><I>file</I> |
| 4883 | |
| 4884 | <DD> |
| 4885 | True if <I>file</I> exists and is a regular file. |
| 4886 | <DT><B>-g </B><I>file</I> |
| 4887 | |
| 4888 | <DD> |
| 4889 | True if <I>file</I> exists and is set-group-id. |
| 4890 | <DT><B>-h </B><I>file</I> |
| 4891 | |
| 4892 | <DD> |
| 4893 | True if <I>file</I> exists and is a symbolic link. |
| 4894 | <DT><B>-k </B><I>file</I> |
| 4895 | |
| 4896 | <DD> |
| 4897 | True if <I>file</I> exists and its ``sticky'' bit is set. |
| 4898 | <DT><B>-p </B><I>file</I> |
| 4899 | |
| 4900 | <DD> |
| 4901 | True if <I>file</I> exists and is a named pipe (FIFO). |
| 4902 | <DT><B>-r </B><I>file</I> |
| 4903 | |
| 4904 | <DD> |
| 4905 | True if <I>file</I> exists and is readable. |
| 4906 | <DT><B>-s </B><I>file</I> |
| 4907 | |
| 4908 | <DD> |
| 4909 | True if <I>file</I> exists and has a size greater than zero. |
| 4910 | <DT><B>-t </B><I>fd</I> |
| 4911 | |
| 4912 | <DD> |
| 4913 | True if file descriptor |
| 4914 | <I>fd</I> |
| 4915 | |
| 4916 | is open and refers to a terminal. |
| 4917 | <DT><B>-u </B><I>file</I> |
| 4918 | |
| 4919 | <DD> |
| 4920 | True if <I>file</I> exists and its set-user-id bit is set. |
| 4921 | <DT><B>-w </B><I>file</I> |
| 4922 | |
| 4923 | <DD> |
| 4924 | True if <I>file</I> exists and is writable. |
| 4925 | <DT><B>-x </B><I>file</I> |
| 4926 | |
| 4927 | <DD> |
| 4928 | True if <I>file</I> exists and is executable. |
| 4929 | <DT><B>-O </B><I>file</I> |
| 4930 | |
| 4931 | <DD> |
| 4932 | True if <I>file</I> exists and is owned by the effective user id. |
| 4933 | <DT><B>-G </B><I>file</I> |
| 4934 | |
| 4935 | <DD> |
| 4936 | True if <I>file</I> exists and is owned by the effective group id. |
| 4937 | <DT><B>-L </B><I>file</I> |
| 4938 | |
| 4939 | <DD> |
| 4940 | True if <I>file</I> exists and is a symbolic link. |
| 4941 | <DT><B>-S </B><I>file</I> |
| 4942 | |
| 4943 | <DD> |
| 4944 | True if <I>file</I> exists and is a socket. |
| 4945 | <DT><B>-N </B><I>file</I> |
| 4946 | |
| 4947 | <DD> |
| 4948 | True if <I>file</I> exists and has been modified since it was last read. |
| 4949 | <DT><I>file1</I> -<B>nt</B> <I>file2</I><DD> |
| 4950 | True if <I>file1</I> is newer (according to modification date) than <I>file2</I>, |
| 4951 | or if <I>file1</I> exists and file2 does not. |
| 4952 | <DT><I>file1</I> -<B>ot</B> <I>file2</I><DD> |
| 4953 | True if <I>file1</I> is older than <I>file2</I>, or if <I>file2</I> exists |
| 4954 | and <I>file1</I> does not. |
| 4955 | <DT><I>file1</I> <B>-ef</B> <I>file2</I><DD> |
| 4956 | True if <I>file1</I> and <I>file2</I> refer to the same device and |
| 4957 | inode numbers. |
| 4958 | <DT><B>-o </B><I>optname</I> |
| 4959 | |
| 4960 | <DD> |
| 4961 | True if shell option |
| 4962 | <I>optname</I> |
| 4963 | |
| 4964 | is enabled. |
| 4965 | See the list of options under the description of the |
| 4966 | <B>-o</B> |
| 4967 | |
| 4968 | option to the |
| 4969 | <B>set</B> |
| 4970 | |
| 4971 | builtin below. |
| 4972 | <DT><B>-z </B><I>string</I> |
| 4973 | |
| 4974 | <DD> |
| 4975 | True if the length of <I>string</I> is zero. |
| 4976 | <DT><I>string</I><DD> |
| 4977 | |
| 4978 | <DT><B>-n </B><I>string</I> |
| 4979 | |
| 4980 | <DD> |
| 4981 | |
| 4982 | True if the length of |
| 4983 | <I>string</I> |
| 4984 | |
| 4985 | is non-zero. |
| 4986 | <DT><I>string1</I> <B>==</B> <I>string2</I><DD> |
| 4987 | True if the strings are equal. <B>=</B> may be used in place of |
| 4988 | <B>==</B> for strict POSIX compliance. |
| 4989 | <DT><I>string1</I> <B>!=</B> <I>string2</I><DD> |
| 4990 | True if the strings are not equal. |
| 4991 | <DT><I>string1</I> <B><</B> <I>string2</I><DD> |
| 4992 | True if <I>string1</I> sorts before <I>string2</I> lexicographically |
| 4993 | in the current locale. |
| 4994 | <DT><I>string1</I> <B>></B> <I>string2</I><DD> |
| 4995 | True if <I>string1</I> sorts after <I>string2</I> lexicographically |
| 4996 | in the current locale. |
| 4997 | <DT><I>arg1</I> <B>OP</B> <I>arg2</I> |
| 4998 | |
| 4999 | <DD> |
| 5000 | <FONT SIZE=-1><B>OP</B> |
| 5001 | |
| 5002 | </FONT> |
| 5003 | is one of |
| 5004 | <B>-eq</B>, |
| 5005 | |
| 5006 | <B>-ne</B>, |
| 5007 | |
| 5008 | <B>-lt</B>, |
| 5009 | |
| 5010 | <B>-le</B>, |
| 5011 | |
| 5012 | <B>-gt</B>, |
| 5013 | |
| 5014 | or |
| 5015 | <B>-ge</B>. |
| 5016 | |
| 5017 | These arithmetic binary operators return true if <I>arg1</I> |
| 5018 | is equal to, not equal to, less than, less than or equal to, |
| 5019 | greater than, or greater than or equal to <I>arg2</I>, respectively. |
| 5020 | <I>Arg1</I> |
| 5021 | |
| 5022 | and |
| 5023 | <I>arg2</I> |
| 5024 | |
| 5025 | may be positive or negative integers. |
| 5026 | |
| 5027 | </DL> |
| 5028 | <A NAME="lbBX"> </A> |
| 5029 | <H3>SIMPLE COMMAND EXPANSION</H3> |
| 5030 | |
| 5031 | When a simple command is executed, the shell performs the following |
| 5032 | expansions, assignments, and redirections, from left to right. |
| 5033 | <DL COMPACT> |
| 5034 | <DT>1.<DD> |
| 5035 | The words that the parser has marked as variable assignments (those |
| 5036 | preceding the command name) and redirections are saved for later |
| 5037 | processing. |
| 5038 | <DT>2.<DD> |
| 5039 | The words that are not variable assignments or redirections are |
| 5040 | expanded. If any words remain after expansion, the first word |
| 5041 | is taken to be the name of the command and the remaining words are |
| 5042 | the arguments. |
| 5043 | <DT>3.<DD> |
| 5044 | Redirections are performed as described above under |
| 5045 | <FONT SIZE=-1><B>REDIRECTION</B>. |
| 5046 | |
| 5047 | </FONT> |
| 5048 | <DT>4.<DD> |
| 5049 | The text after the <B>=</B> in each variable assignment undergoes tilde |
| 5050 | expansion, parameter expansion, command substitution, arithmetic expansion, |
| 5051 | and quote removal before being assigned to the variable. |
| 5052 | </DL> |
| 5053 | <P> |
| 5054 | |
| 5055 | If no command name results, the variable assignments affect the current |
| 5056 | shell environment. Otherwise, the variables are added to the environment |
| 5057 | of the executed command and do not affect the current shell environment. |
| 5058 | If any of the assignments attempts to assign a value to a readonly variable, |
| 5059 | an error occurs, and the command exits with a non-zero status. |
| 5060 | <P> |
| 5061 | |
| 5062 | If no command name results, redirections are performed, but do not |
| 5063 | affect the current shell environment. A redirection error causes the |
| 5064 | command to exit with a non-zero status. |
| 5065 | <P> |
| 5066 | |
| 5067 | If there is a command name left after expansion, execution proceeds as |
| 5068 | described below. Otherwise, the command exits. If one of the expansions |
| 5069 | contained a command substitution, the exit status of the command is |
| 5070 | the exit status of the last command substitution performed. If there |
| 5071 | were no command substitutions, the command exits with a status of zero. |
| 5072 | <A NAME="lbBY"> </A> |
| 5073 | <H3>COMMAND EXECUTION</H3> |
| 5074 | |
| 5075 | After a command has been split into words, if it results in a |
| 5076 | simple command and an optional list of arguments, the following |
| 5077 | actions are taken. |
| 5078 | <P> |
| 5079 | |
| 5080 | If the command name contains no slashes, the shell attempts to |
| 5081 | locate it. If there exists a shell function by that name, that |
| 5082 | function is invoked as described above in |
| 5083 | <FONT SIZE=-1><B>FUNCTIONS</B>. |
| 5084 | |
| 5085 | </FONT> |
| 5086 | If the name does not match a function, the shell searches for |
| 5087 | it in the list of shell builtins. If a match is found, that |
| 5088 | builtin is invoked. |
| 5089 | <P> |
| 5090 | |
| 5091 | If the name is neither a shell function nor a builtin, |
| 5092 | and contains no slashes, |
| 5093 | <B>bash</B> |
| 5094 | |
| 5095 | searches each element of the |
| 5096 | <FONT SIZE=-1><B>PATH</B> |
| 5097 | |
| 5098 | </FONT> |
| 5099 | for a directory containing an executable file by that name. |
| 5100 | <B>Bash</B> |
| 5101 | |
| 5102 | uses a hash table to remember the full pathnames of executable |
| 5103 | files (see |
| 5104 | <B>hash</B> |
| 5105 | |
| 5106 | under |
| 5107 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 5108 | |
| 5109 | </FONT> |
| 5110 | below). |
| 5111 | A full search of the directories in |
| 5112 | <FONT SIZE=-1><B>PATH</B> |
| 5113 | |
| 5114 | </FONT> |
| 5115 | is performed only if the command is not found in the hash table. |
| 5116 | If the search is unsuccessful, the shell searches for a defined shell |
| 5117 | function named <B>command_not_found_handle</B>. |
| 5118 | If that function exists, it is invoked with the original command and |
| 5119 | the original command's arguments as its arguments, and the function's |
| 5120 | exit status becomes the exit status of the shell. |
| 5121 | If that function is not defined, the shell prints an error |
| 5122 | message and returns an exit status of 127. |
| 5123 | <P> |
| 5124 | |
| 5125 | If the search is successful, or if the command name contains |
| 5126 | one or more slashes, the shell executes the named program in a |
| 5127 | separate execution environment. |
| 5128 | Argument 0 is set to the name given, and the remaining arguments |
| 5129 | to the command are set to the arguments given, if any. |
| 5130 | <P> |
| 5131 | |
| 5132 | If this execution fails because the file is not in executable |
| 5133 | format, and the file is not a directory, it is assumed to be |
| 5134 | a <I>shell script</I>, a file |
| 5135 | containing shell commands. A subshell is spawned to execute |
| 5136 | it. This subshell reinitializes itself, so |
| 5137 | that the effect is as if a new shell had been invoked |
| 5138 | to handle the script, with the exception that the locations of |
| 5139 | commands remembered by the parent (see |
| 5140 | <B>hash</B> |
| 5141 | |
| 5142 | below under |
| 5143 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>)</FONT> |
| 5144 | are retained by the child. |
| 5145 | <P> |
| 5146 | |
| 5147 | If the program is a file beginning with |
| 5148 | <B>#!</B>, |
| 5149 | |
| 5150 | the remainder of the first line specifies an interpreter |
| 5151 | for the program. The shell executes the |
| 5152 | specified interpreter on operating systems that do not |
| 5153 | handle this executable format themselves. The arguments to the |
| 5154 | interpreter consist of a single optional argument following the |
| 5155 | interpreter name on the first line of the program, followed |
| 5156 | by the name of the program, followed by the command |
| 5157 | arguments, if any. |
| 5158 | <A NAME="lbBZ"> </A> |
| 5159 | <H3>COMMAND EXECUTION ENVIRONMENT</H3> |
| 5160 | |
| 5161 | The shell has an <I>execution environment</I>, which consists of the |
| 5162 | following: |
| 5163 | <P> |
| 5164 | <DL COMPACT> |
| 5165 | <DT>*<DD> |
| 5166 | open files inherited by the shell at invocation, as modified by |
| 5167 | redirections supplied to the <B>exec</B> builtin |
| 5168 | <DT>*<DD> |
| 5169 | the current working directory as set by <B>cd</B>, <B>pushd</B>, or |
| 5170 | <B>popd</B>, or inherited by the shell at invocation |
| 5171 | <DT>*<DD> |
| 5172 | the file creation mode mask as set by <B>umask</B> or inherited from |
| 5173 | the shell's parent |
| 5174 | <DT>*<DD> |
| 5175 | current traps set by <B>trap</B> |
| 5176 | <DT>*<DD> |
| 5177 | shell parameters that are set by variable assignment or with <B>set</B> |
| 5178 | or inherited from the shell's parent in the environment |
| 5179 | <DT>*<DD> |
| 5180 | shell functions defined during execution or inherited from the shell's |
| 5181 | parent in the environment |
| 5182 | <DT>*<DD> |
| 5183 | options enabled at invocation (either by default or with command-line |
| 5184 | arguments) or by <B>set</B> |
| 5185 | <DT>*<DD> |
| 5186 | options enabled by <B>shopt</B> |
| 5187 | <DT>*<DD> |
| 5188 | shell aliases defined with <B>alias</B> |
| 5189 | <DT>*<DD> |
| 5190 | various process IDs, including those of background jobs, the value |
| 5191 | of <B>$$</B>, and the value of <B>$PPID</B> |
| 5192 | </DL> |
| 5193 | <P> |
| 5194 | |
| 5195 | When a simple command other than a builtin or shell function |
| 5196 | is to be executed, it |
| 5197 | is invoked in a separate execution environment that consists of |
| 5198 | the following. Unless otherwise noted, the values are inherited |
| 5199 | from the shell. |
| 5200 | <P> |
| 5201 | <DL COMPACT> |
| 5202 | <DT>*<DD> |
| 5203 | the shell's open files, plus any modifications and additions specified |
| 5204 | by redirections to the command |
| 5205 | <DT>*<DD> |
| 5206 | the current working directory |
| 5207 | <DT>*<DD> |
| 5208 | the file creation mode mask |
| 5209 | <DT>*<DD> |
| 5210 | shell variables and functions marked for export, along with variables |
| 5211 | exported for the command, passed in the environment |
| 5212 | <DT>*<DD> |
| 5213 | traps caught by the shell are reset to the values inherited from the |
| 5214 | shell's parent, and traps ignored by the shell are ignored |
| 5215 | </DL> |
| 5216 | <P> |
| 5217 | |
| 5218 | A command invoked in this separate environment cannot affect the |
| 5219 | shell's execution environment. |
| 5220 | <P> |
| 5221 | |
| 5222 | Command substitution, commands grouped with parentheses, |
| 5223 | and asynchronous commands are invoked in a |
| 5224 | subshell environment that is a duplicate of the shell environment, |
| 5225 | except that traps caught by the shell are reset to the values |
| 5226 | that the shell inherited from its parent at invocation. Builtin |
| 5227 | commands that are invoked as part of a pipeline are also executed in a |
| 5228 | subshell environment. Changes made to the subshell environment |
| 5229 | cannot affect the shell's execution environment. |
| 5230 | <P> |
| 5231 | |
| 5232 | Subshells spawned to execute command substitutions inherit the value of |
| 5233 | the <B>-e</B> option from the parent shell. When not in posix mode, |
| 5234 | Bash clears the <B>-e</B> option in such subshells. |
| 5235 | <P> |
| 5236 | |
| 5237 | If a command is followed by a <B>&</B> and job control is not active, the |
| 5238 | default standard input for the command is the empty file <I>/dev/null</I>. |
| 5239 | Otherwise, the invoked command inherits the file descriptors of the calling |
| 5240 | shell as modified by redirections. |
| 5241 | <A NAME="lbCA"> </A> |
| 5242 | <H3>ENVIRONMENT</H3> |
| 5243 | |
| 5244 | When a program is invoked it is given an array of strings |
| 5245 | called the |
| 5246 | <I>environment</I>. |
| 5247 | |
| 5248 | This is a list of |
| 5249 | <I>name</I>-<I>value</I> pairs, of the form |
| 5250 | <I>name</I>=value. |
| 5251 | |
| 5252 | <P> |
| 5253 | |
| 5254 | The shell provides several ways to manipulate the environment. |
| 5255 | On invocation, the shell scans its own environment and |
| 5256 | creates a parameter for each name found, automatically marking |
| 5257 | it for |
| 5258 | <I>export</I> |
| 5259 | |
| 5260 | to child processes. Executed commands inherit the environment. |
| 5261 | The |
| 5262 | <B>export</B> |
| 5263 | |
| 5264 | and |
| 5265 | <B>declare -x</B> |
| 5266 | |
| 5267 | commands allow parameters and functions to be added to and |
| 5268 | deleted from the environment. If the value of a parameter |
| 5269 | in the environment is modified, the new value becomes part |
| 5270 | of the environment, replacing the old. The environment |
| 5271 | inherited by any executed command consists of the shell's |
| 5272 | initial environment, whose values may be modified in the shell, |
| 5273 | less any pairs removed by the |
| 5274 | <B>unset</B> |
| 5275 | |
| 5276 | command, plus any additions via the |
| 5277 | <B>export</B> |
| 5278 | |
| 5279 | and |
| 5280 | <B>declare -x</B> |
| 5281 | |
| 5282 | commands. |
| 5283 | <P> |
| 5284 | |
| 5285 | The environment for any |
| 5286 | <I>simple command</I> |
| 5287 | |
| 5288 | or function may be augmented temporarily by prefixing it with |
| 5289 | parameter assignments, as described above in |
| 5290 | <FONT SIZE=-1><B>PARAMETERS</B>. |
| 5291 | |
| 5292 | </FONT> |
| 5293 | These assignment statements affect only the environment seen |
| 5294 | by that command. |
| 5295 | <P> |
| 5296 | |
| 5297 | If the |
| 5298 | <B>-k</B> |
| 5299 | |
| 5300 | option is set (see the |
| 5301 | <B>set</B> |
| 5302 | |
| 5303 | builtin command below), then |
| 5304 | <I>all</I> |
| 5305 | |
| 5306 | parameter assignments are placed in the environment for a command, |
| 5307 | not just those that precede the command name. |
| 5308 | <P> |
| 5309 | |
| 5310 | When |
| 5311 | <B>bash</B> |
| 5312 | |
| 5313 | invokes an external command, the variable |
| 5314 | <B>_</B> |
| 5315 | |
| 5316 | is set to the full file name of the command and passed to that |
| 5317 | command in its environment. |
| 5318 | <A NAME="lbCB"> </A> |
| 5319 | <H3>EXIT STATUS</H3> |
| 5320 | |
| 5321 | <P> |
| 5322 | |
| 5323 | The exit status of an executed command is the value returned by the |
| 5324 | <I>waitpid</I> system call or equivalent function. Exit statuses |
| 5325 | fall between 0 and 255, though, as explained below, the shell may |
| 5326 | use values above 125 specially. Exit statuses from shell builtins and |
| 5327 | compound commands are also limited to this range. Under certain |
| 5328 | circumstances, the shell will use special values to indicate specific |
| 5329 | failure modes. |
| 5330 | <P> |
| 5331 | |
| 5332 | For the shell's purposes, a command which exits with a |
| 5333 | zero exit status has succeeded. An exit status of zero |
| 5334 | indicates success. A non-zero exit status indicates failure. |
| 5335 | When a command terminates on a fatal signal <I>N</I>, <B>bash</B> uses |
| 5336 | the value of 128+<I>N</I> as the exit status. |
| 5337 | <P> |
| 5338 | |
| 5339 | If a command is not found, the child process created to |
| 5340 | execute it returns a status of 127. If a command is found |
| 5341 | but is not executable, the return status is 126. |
| 5342 | <P> |
| 5343 | |
| 5344 | If a command fails because of an error during expansion or redirection, |
| 5345 | the exit status is greater than zero. |
| 5346 | <P> |
| 5347 | |
| 5348 | Shell builtin commands return a status of 0 (<I>true</I>) if |
| 5349 | successful, and non-zero (<I>false</I>) if an error occurs |
| 5350 | while they execute. |
| 5351 | All builtins return an exit status of 2 to indicate incorrect usage. |
| 5352 | <P> |
| 5353 | |
| 5354 | <B>Bash</B> itself returns the exit status of the last command |
| 5355 | executed, unless a syntax error occurs, in which case it exits |
| 5356 | with a non-zero value. See also the <B>exit</B> builtin |
| 5357 | command below. |
| 5358 | <A NAME="lbCC"> </A> |
| 5359 | <H3>SIGNALS</H3> |
| 5360 | |
| 5361 | When <B>bash</B> is interactive, in the absence of any traps, it ignores |
| 5362 | <FONT SIZE=-1><B>SIGTERM</B> |
| 5363 | |
| 5364 | </FONT> |
| 5365 | (so that <B>kill 0</B> does not kill an interactive shell), |
| 5366 | and |
| 5367 | <FONT SIZE=-1><B>SIGINT</B> |
| 5368 | |
| 5369 | </FONT> |
| 5370 | is caught and handled (so that the <B>wait</B> builtin is interruptible). |
| 5371 | In all cases, <B>bash</B> ignores |
| 5372 | <FONT SIZE=-1><B>SIGQUIT</B>. |
| 5373 | |
| 5374 | </FONT> |
| 5375 | If job control is in effect, |
| 5376 | <B>bash</B> |
| 5377 | |
| 5378 | ignores |
| 5379 | <FONT SIZE=-1><B>SIGTTIN</B>, |
| 5380 | |
| 5381 | </FONT> |
| 5382 | <FONT SIZE=-1><B>SIGTTOU</B>, |
| 5383 | |
| 5384 | </FONT> |
| 5385 | and |
| 5386 | <FONT SIZE=-1><B>SIGTSTP</B>. |
| 5387 | |
| 5388 | </FONT> |
| 5389 | <P> |
| 5390 | |
| 5391 | Non-builtin commands run by <B>bash</B> have signal handlers |
| 5392 | set to the values inherited by the shell from its parent. |
| 5393 | When job control is not in effect, asynchronous commands |
| 5394 | ignore |
| 5395 | <FONT SIZE=-1><B>SIGINT</B> |
| 5396 | |
| 5397 | </FONT> |
| 5398 | and |
| 5399 | <FONT SIZE=-1><B>SIGQUIT</B> |
| 5400 | |
| 5401 | </FONT> |
| 5402 | in addition to these inherited handlers. |
| 5403 | Commands run as a result of command substitution ignore the |
| 5404 | keyboard-generated job control signals |
| 5405 | <FONT SIZE=-1><B>SIGTTIN</B>, |
| 5406 | |
| 5407 | </FONT> |
| 5408 | <FONT SIZE=-1><B>SIGTTOU</B>, |
| 5409 | |
| 5410 | </FONT> |
| 5411 | and |
| 5412 | <FONT SIZE=-1><B>SIGTSTP</B>. |
| 5413 | |
| 5414 | </FONT> |
| 5415 | <P> |
| 5416 | |
| 5417 | The shell exits by default upon receipt of a |
| 5418 | <FONT SIZE=-1><B>SIGHUP</B>. |
| 5419 | |
| 5420 | </FONT> |
| 5421 | Before exiting, an interactive shell resends the |
| 5422 | <FONT SIZE=-1><B>SIGHUP</B> |
| 5423 | |
| 5424 | </FONT> |
| 5425 | to all jobs, running or stopped. |
| 5426 | Stopped jobs are sent |
| 5427 | <FONT SIZE=-1><B>SIGCONT</B> |
| 5428 | |
| 5429 | </FONT> |
| 5430 | to ensure that they receive the |
| 5431 | <FONT SIZE=-1><B>SIGHUP</B>. |
| 5432 | |
| 5433 | </FONT> |
| 5434 | To prevent the shell from |
| 5435 | sending the signal to a particular job, it should be removed from the |
| 5436 | jobs table with the |
| 5437 | <B>disown</B> |
| 5438 | |
| 5439 | builtin (see |
| 5440 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 5441 | |
| 5442 | </FONT> |
| 5443 | below) or marked |
| 5444 | to not receive |
| 5445 | <FONT SIZE=-1><B>SIGHUP</B> |
| 5446 | |
| 5447 | </FONT> |
| 5448 | using |
| 5449 | <B>disown -h</B>. |
| 5450 | |
| 5451 | <P> |
| 5452 | |
| 5453 | If the |
| 5454 | <B>huponexit</B> |
| 5455 | |
| 5456 | shell option has been set with |
| 5457 | <B>shopt</B>, |
| 5458 | |
| 5459 | <B>bash</B> |
| 5460 | |
| 5461 | sends a |
| 5462 | <FONT SIZE=-1><B>SIGHUP</B> |
| 5463 | |
| 5464 | </FONT> |
| 5465 | to all jobs when an interactive login shell exits. |
| 5466 | <P> |
| 5467 | |
| 5468 | If <B>bash</B> is waiting for a command to complete and receives a signal |
| 5469 | for which a trap has been set, the trap will not be executed until |
| 5470 | the command completes. |
| 5471 | When <B>bash</B> is waiting for an asynchronous command via the <B>wait</B> |
| 5472 | builtin, the reception of a signal for which a trap has been set will |
| 5473 | cause the <B>wait</B> builtin to return immediately with an exit status |
| 5474 | greater than 128, immediately after which the trap is executed. |
| 5475 | <A NAME="lbCD"> </A> |
| 5476 | <H3>JOB CONTROL</H3> |
| 5477 | |
| 5478 | <I>Job control</I> |
| 5479 | |
| 5480 | refers to the ability to selectively stop (<I>suspend</I>) |
| 5481 | the execution of processes and continue (<I>resume</I>) |
| 5482 | their execution at a later point. A user typically employs |
| 5483 | this facility via an interactive interface supplied jointly |
| 5484 | by the system's terminal driver and |
| 5485 | <B>bash</B>. |
| 5486 | |
| 5487 | <P> |
| 5488 | |
| 5489 | The shell associates a |
| 5490 | <I>job</I> |
| 5491 | |
| 5492 | with each pipeline. It keeps a table of currently executing |
| 5493 | jobs, which may be listed with the |
| 5494 | <B>jobs</B> |
| 5495 | |
| 5496 | command. When |
| 5497 | <B>bash</B> |
| 5498 | |
| 5499 | starts a job asynchronously (in the |
| 5500 | <I>background</I>), |
| 5501 | |
| 5502 | it prints a line that looks like: |
| 5503 | <DL COMPACT><DT><DD> |
| 5504 | <P> |
| 5505 | |
| 5506 | [1] 25647 |
| 5507 | </DL> |
| 5508 | |
| 5509 | <P> |
| 5510 | |
| 5511 | indicating that this job is job number 1 and that the process ID |
| 5512 | of the last process in the pipeline associated with this job is 25647. |
| 5513 | All of the processes in a single pipeline are members of the same job. |
| 5514 | <B>Bash</B> |
| 5515 | |
| 5516 | uses the |
| 5517 | <I>job</I> |
| 5518 | |
| 5519 | abstraction as the basis for job control. |
| 5520 | <P> |
| 5521 | |
| 5522 | To facilitate the implementation of the user interface to job |
| 5523 | control, the operating system maintains the notion of a <I>current terminal |
| 5524 | process group ID</I>. Members of this process group (processes whose |
| 5525 | process group ID is equal to the current terminal process group ID) |
| 5526 | receive keyboard-generated signals such as |
| 5527 | <FONT SIZE=-1><B>SIGINT</B>. |
| 5528 | |
| 5529 | </FONT> |
| 5530 | These processes are said to be in the |
| 5531 | <I>foreground</I>. |
| 5532 | |
| 5533 | <I>Background</I> |
| 5534 | |
| 5535 | processes are those whose process group ID differs from the terminal's; |
| 5536 | such processes are immune to keyboard-generated signals. |
| 5537 | Only foreground processes are allowed to read from or write to the |
| 5538 | terminal. Background processes which attempt to read from (write to) the |
| 5539 | terminal are sent a |
| 5540 | <FONT SIZE=-1><B>SIGTTIN (SIGTTOU)</B> |
| 5541 | |
| 5542 | </FONT> |
| 5543 | signal by the terminal driver, |
| 5544 | which, unless caught, suspends the process. |
| 5545 | <P> |
| 5546 | |
| 5547 | If the operating system on which |
| 5548 | <B>bash</B> |
| 5549 | |
| 5550 | is running supports |
| 5551 | job control, |
| 5552 | <B>bash</B> |
| 5553 | |
| 5554 | contains facilities to use it. |
| 5555 | Typing the |
| 5556 | <I>suspend</I> |
| 5557 | |
| 5558 | character (typically |
| 5559 | <B>^Z</B>, |
| 5560 | |
| 5561 | Control-Z) while a process is running |
| 5562 | causes that process to be stopped and returns control to |
| 5563 | <B>bash</B>. |
| 5564 | |
| 5565 | Typing the |
| 5566 | <I>delayed suspend</I> |
| 5567 | |
| 5568 | character (typically |
| 5569 | <B>^Y</B>, |
| 5570 | |
| 5571 | Control-Y) causes the process to be stopped when it |
| 5572 | attempts to read input from the terminal, and control to |
| 5573 | be returned to |
| 5574 | <B>bash</B>. |
| 5575 | |
| 5576 | The user may then manipulate the state of this job, using the |
| 5577 | <B>bg</B> |
| 5578 | |
| 5579 | command to continue it in the background, the |
| 5580 | <B>fg</B> |
| 5581 | |
| 5582 | command to continue it in the foreground, or |
| 5583 | the |
| 5584 | <B>kill</B> |
| 5585 | |
| 5586 | command to kill it. A <B>^Z</B> takes effect immediately, |
| 5587 | and has the additional side effect of causing pending output |
| 5588 | and typeahead to be discarded. |
| 5589 | <P> |
| 5590 | |
| 5591 | There are a number of ways to refer to a job in the shell. |
| 5592 | The character |
| 5593 | <B>%</B> |
| 5594 | |
| 5595 | introduces a job specification (<I>jobspec</I>). Job number |
| 5596 | <I>n</I> |
| 5597 | |
| 5598 | may be referred to as |
| 5599 | <B>%n</B>. |
| 5600 | |
| 5601 | A job may also be referred to using a prefix of the name used to |
| 5602 | start it, or using a substring that appears in its command line. |
| 5603 | For example, |
| 5604 | <B>%ce</B> |
| 5605 | |
| 5606 | refers to a stopped |
| 5607 | <B>ce</B> |
| 5608 | |
| 5609 | job. If a prefix matches more than one job, |
| 5610 | <B>bash</B> |
| 5611 | |
| 5612 | reports an error. Using |
| 5613 | <B>%?ce</B>, |
| 5614 | |
| 5615 | on the other hand, refers to any job containing the string |
| 5616 | <B>ce</B> |
| 5617 | |
| 5618 | in its command line. If the substring matches more than one job, |
| 5619 | <B>bash</B> |
| 5620 | |
| 5621 | reports an error. The symbols |
| 5622 | <B>%%</B> |
| 5623 | |
| 5624 | and |
| 5625 | <B>%+</B> |
| 5626 | |
| 5627 | refer to the shell's notion of the |
| 5628 | <I>current job</I>, |
| 5629 | |
| 5630 | which is the last job stopped while it was in |
| 5631 | the foreground or started in the background. |
| 5632 | The |
| 5633 | <I>previous job</I> |
| 5634 | |
| 5635 | may be referenced using |
| 5636 | <B>%-</B>. |
| 5637 | |
| 5638 | If there is only a single job, <B>%+</B> and <B>%-</B> can both be used |
| 5639 | to refer to that job. |
| 5640 | In output pertaining to jobs (e.g., the output of the |
| 5641 | <B>jobs</B> |
| 5642 | |
| 5643 | command), the current job is always flagged with a |
| 5644 | <B>+</B>, |
| 5645 | |
| 5646 | and the previous job with a |
| 5647 | <B>-</B>. |
| 5648 | |
| 5649 | A single % (with no accompanying job specification) also refers to the |
| 5650 | current job. |
| 5651 | <P> |
| 5652 | |
| 5653 | Simply naming a job can be used to bring it into the |
| 5654 | foreground: |
| 5655 | <B>%1</B> |
| 5656 | |
| 5657 | is a synonym for |
| 5658 | <B>``fg %1''</B>, |
| 5659 | bringing job 1 from the background into the foreground. |
| 5660 | Similarly, |
| 5661 | <B>``%1 &''</B> |
| 5662 | |
| 5663 | resumes job 1 in the background, equivalent to |
| 5664 | <B>``bg %1''</B>. |
| 5665 | <P> |
| 5666 | |
| 5667 | The shell learns immediately whenever a job changes state. |
| 5668 | Normally, |
| 5669 | <B>bash</B> |
| 5670 | |
| 5671 | waits until it is about to print a prompt before reporting |
| 5672 | changes in a job's status so as to not interrupt |
| 5673 | any other output. If the |
| 5674 | <B>-b</B> |
| 5675 | |
| 5676 | option to the |
| 5677 | <B>set</B> |
| 5678 | |
| 5679 | builtin command |
| 5680 | is enabled, |
| 5681 | <B>bash</B> |
| 5682 | |
| 5683 | reports such changes immediately. |
| 5684 | Any trap on |
| 5685 | <FONT SIZE=-1><B>SIGCHLD</B> |
| 5686 | |
| 5687 | </FONT> |
| 5688 | is executed for each child that exits. |
| 5689 | <P> |
| 5690 | |
| 5691 | If an attempt to exit |
| 5692 | <B>bash</B> |
| 5693 | |
| 5694 | is made while jobs are stopped (or, if the <B>checkjobs</B> shell option has |
| 5695 | been enabled using the <B>shopt</B> builtin, running), the shell prints a |
| 5696 | warning message, and, if the <B>checkjobs</B> option is enabled, lists the |
| 5697 | jobs and their statuses. |
| 5698 | The |
| 5699 | <B>jobs</B> |
| 5700 | |
| 5701 | command may then be used to inspect their status. |
| 5702 | If a second attempt to exit is made without an intervening command, |
| 5703 | the shell does not print another warning, and any stopped |
| 5704 | jobs are terminated. |
| 5705 | <A NAME="lbCE"> </A> |
| 5706 | <H3>PROMPTING</H3> |
| 5707 | |
| 5708 | When executing interactively, |
| 5709 | <B>bash</B> |
| 5710 | |
| 5711 | displays the primary prompt |
| 5712 | <FONT SIZE=-1><B>PS1</B> |
| 5713 | |
| 5714 | </FONT> |
| 5715 | when it is ready to read a command, and the secondary prompt |
| 5716 | <FONT SIZE=-1><B>PS2</B> |
| 5717 | |
| 5718 | </FONT> |
| 5719 | when it needs more input to complete a command. |
| 5720 | <B>Bash</B> |
| 5721 | |
| 5722 | allows these prompt strings to be customized by inserting a number of |
| 5723 | backslash-escaped special characters that are decoded as follows: |
| 5724 | <DL COMPACT><DT><DD> |
| 5725 | |
| 5726 | <DL COMPACT> |
| 5727 | <DT><B>\a</B> |
| 5728 | |
| 5729 | <DD> |
| 5730 | an ASCII bell character (07) |
| 5731 | <DT><B>\d</B> |
| 5732 | |
| 5733 | <DD> |
| 5734 | the date in "Weekday Month Date" format (e.g., "Tue May 26") |
| 5735 | <DT><B>\D{</B><I>format</I>} |
| 5736 | |
| 5737 | <DD> |
| 5738 | the <I>format</I> is passed to <I>strftime</I>(3) and the result is inserted |
| 5739 | into the prompt string; an empty <I>format</I> results in a locale-specific |
| 5740 | time representation. The braces are required |
| 5741 | <DT><B>\e</B> |
| 5742 | |
| 5743 | <DD> |
| 5744 | an ASCII escape character (033) |
| 5745 | <DT><B>\h</B> |
| 5746 | |
| 5747 | <DD> |
| 5748 | the hostname up to the first `.' |
| 5749 | <DT><B>\H</B> |
| 5750 | |
| 5751 | <DD> |
| 5752 | the hostname |
| 5753 | <DT><B>\j</B> |
| 5754 | |
| 5755 | <DD> |
| 5756 | the number of jobs currently managed by the shell |
| 5757 | <DT><B>\l</B> |
| 5758 | |
| 5759 | <DD> |
| 5760 | the basename of the shell's terminal device name |
| 5761 | <DT><B>\n</B> |
| 5762 | |
| 5763 | <DD> |
| 5764 | newline |
| 5765 | <DT><B>\r</B> |
| 5766 | |
| 5767 | <DD> |
| 5768 | carriage return |
| 5769 | <DT><B>\s</B> |
| 5770 | |
| 5771 | <DD> |
| 5772 | the name of the shell, the basename of |
| 5773 | <B>$0</B> |
| 5774 | |
| 5775 | (the portion following the final slash) |
| 5776 | <DT><B>\t</B> |
| 5777 | |
| 5778 | <DD> |
| 5779 | the current time in 24-hour HH:MM:SS format |
| 5780 | <DT><B>\T</B> |
| 5781 | |
| 5782 | <DD> |
| 5783 | the current time in 12-hour HH:MM:SS format |
| 5784 | <DT><B>\@</B> |
| 5785 | |
| 5786 | <DD> |
| 5787 | the current time in 12-hour am/pm format |
| 5788 | <DT><B>\A</B> |
| 5789 | |
| 5790 | <DD> |
| 5791 | the current time in 24-hour HH:MM format |
| 5792 | <DT><B>\u</B> |
| 5793 | |
| 5794 | <DD> |
| 5795 | the username of the current user |
| 5796 | <DT><B>\v</B> |
| 5797 | |
| 5798 | <DD> |
| 5799 | the version of <B>bash</B> (e.g., 2.00) |
| 5800 | <DT><B>\V</B> |
| 5801 | |
| 5802 | <DD> |
| 5803 | the release of <B>bash</B>, version + patch level (e.g., 2.00.0) |
| 5804 | <DT><B>\w</B> |
| 5805 | |
| 5806 | <DD> |
| 5807 | the current working directory, with <B>$HOME</B> abbreviated with a tilde |
| 5808 | (uses the <B>$PROMPT_DIRTRIM</B> variable) |
| 5809 | <DT><B>\W</B> |
| 5810 | |
| 5811 | <DD> |
| 5812 | the basename of the current working directory, with <B>$HOME</B> |
| 5813 | abbreviated with a tilde |
| 5814 | <DT><B>\!</B> |
| 5815 | |
| 5816 | <DD> |
| 5817 | the history number of this command |
| 5818 | <DT><B>\#</B> |
| 5819 | |
| 5820 | <DD> |
| 5821 | the command number of this command |
| 5822 | <DT><B>\$</B> |
| 5823 | |
| 5824 | <DD> |
| 5825 | if the effective UID is 0, a |
| 5826 | <B>#</B>, |
| 5827 | |
| 5828 | otherwise a |
| 5829 | <B>$</B> |
| 5830 | |
| 5831 | <DT><B>\</B><I>nnn</I> |
| 5832 | |
| 5833 | <DD> |
| 5834 | the character corresponding to the octal number <I>nnn</I> |
| 5835 | <DT><B>\\</B> |
| 5836 | |
| 5837 | <DD> |
| 5838 | a backslash |
| 5839 | <DT><B>\[</B> |
| 5840 | |
| 5841 | <DD> |
| 5842 | begin a sequence of non-printing characters, which could be used to |
| 5843 | embed a terminal control sequence into the prompt |
| 5844 | <DT><B>\]</B> |
| 5845 | |
| 5846 | <DD> |
| 5847 | end a sequence of non-printing characters |
| 5848 | |
| 5849 | </DL></DL> |
| 5850 | |
| 5851 | <P> |
| 5852 | |
| 5853 | The command number and the history number are usually different: |
| 5854 | the history number of a command is its position in the history |
| 5855 | list, which may include commands restored from the history file |
| 5856 | (see |
| 5857 | <FONT SIZE=-1><B>HISTORY</B> |
| 5858 | |
| 5859 | </FONT> |
| 5860 | below), while the command number is the position in the sequence |
| 5861 | of commands executed during the current shell session. |
| 5862 | After the string is decoded, it is expanded via |
| 5863 | parameter expansion, command substitution, arithmetic |
| 5864 | expansion, and quote removal, subject to the value of the |
| 5865 | <B>promptvars</B> |
| 5866 | |
| 5867 | shell option (see the description of the |
| 5868 | <B>shopt</B> |
| 5869 | |
| 5870 | command under |
| 5871 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 5872 | |
| 5873 | </FONT> |
| 5874 | below). |
| 5875 | <A NAME="lbCF"> </A> |
| 5876 | <H3>READLINE</H3> |
| 5877 | |
| 5878 | This is the library that handles reading input when using an interactive |
| 5879 | shell, unless the |
| 5880 | <B>--noediting</B> |
| 5881 | |
| 5882 | option is given at shell invocation. |
| 5883 | Line editing is also used when using the <B>-e</B> option to the |
| 5884 | <B>read</B> builtin. |
| 5885 | By default, the line editing commands are similar to those of emacs. |
| 5886 | A vi-style line editing interface is also available. |
| 5887 | Line editing can be enabled at any time using the |
| 5888 | <B>-o emacs</B> |
| 5889 | |
| 5890 | or |
| 5891 | <B>-o vi</B> |
| 5892 | |
| 5893 | options to the |
| 5894 | <B>set</B> |
| 5895 | |
| 5896 | builtin (see |
| 5897 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 5898 | |
| 5899 | </FONT> |
| 5900 | below). |
| 5901 | To turn off line editing after the shell is running, use the |
| 5902 | <B>+o emacs</B> |
| 5903 | |
| 5904 | or |
| 5905 | <B>+o vi</B> |
| 5906 | |
| 5907 | options to the |
| 5908 | <B>set</B> |
| 5909 | |
| 5910 | builtin. |
| 5911 | <A NAME="lbCG"> </A> |
| 5912 | <H4>Readline Notation</H4> |
| 5913 | |
| 5914 | <P> |
| 5915 | |
| 5916 | In this section, the emacs-style notation is used to denote |
| 5917 | keystrokes. Control keys are denoted by C-<I>key</I>, e.g., C-n |
| 5918 | means Control-N. Similarly, |
| 5919 | <I>meta</I> |
| 5920 | |
| 5921 | keys are denoted by M-<I>key</I>, so M-x means Meta-X. (On keyboards |
| 5922 | without a |
| 5923 | <I>meta</I> |
| 5924 | |
| 5925 | key, M-<I>x</I> means ESC <I>x</I>, i.e., press the Escape key |
| 5926 | then the |
| 5927 | <I>x</I> |
| 5928 | |
| 5929 | key. This makes ESC the <I>meta prefix</I>. |
| 5930 | The combination M-C-<I>x</I> means ESC-Control-<I>x</I>, |
| 5931 | or press the Escape key |
| 5932 | then hold the Control key while pressing the |
| 5933 | <I>x</I> |
| 5934 | |
| 5935 | key.) |
| 5936 | <P> |
| 5937 | |
| 5938 | Readline commands may be given numeric |
| 5939 | <I>arguments</I>, |
| 5940 | |
| 5941 | which normally act as a repeat count. |
| 5942 | Sometimes, however, it is the sign of the argument that is significant. |
| 5943 | Passing a negative argument to a command that acts in the forward |
| 5944 | direction (e.g., <B>kill-line</B>) causes that command to act in a |
| 5945 | backward direction. |
| 5946 | Commands whose behavior with arguments deviates from this are noted |
| 5947 | below. |
| 5948 | <P> |
| 5949 | |
| 5950 | When a command is described as <I>killing</I> text, the text |
| 5951 | deleted is saved for possible future retrieval |
| 5952 | (<I>yanking</I>). The killed text is saved in a |
| 5953 | <I>kill ring</I>. Consecutive kills cause the text to be |
| 5954 | accumulated into one unit, which can be yanked all at once. |
| 5955 | Commands which do not kill text separate the chunks of text |
| 5956 | on the kill ring. |
| 5957 | <A NAME="lbCH"> </A> |
| 5958 | <H4>Readline Initialization</H4> |
| 5959 | |
| 5960 | <P> |
| 5961 | |
| 5962 | Readline is customized by putting commands in an initialization |
| 5963 | file (the <I>inputrc</I> file). |
| 5964 | The name of this file is taken from the value of the |
| 5965 | <FONT SIZE=-1><B>INPUTRC</B> |
| 5966 | |
| 5967 | </FONT> |
| 5968 | variable. If that variable is unset, the default is |
| 5969 | <A HREF="file:~/.inputrc"><I>~/.inputrc</I></A>. |
| 5970 | |
| 5971 | When a program which uses the readline library starts up, the |
| 5972 | initialization file is read, and the key bindings and variables |
| 5973 | are set. |
| 5974 | There are only a few basic constructs allowed in the |
| 5975 | readline initialization file. |
| 5976 | Blank lines are ignored. |
| 5977 | Lines beginning with a <B>#</B> are comments. |
| 5978 | Lines beginning with a <B>$</B> indicate conditional constructs. |
| 5979 | Other lines denote key bindings and variable settings. |
| 5980 | <P> |
| 5981 | |
| 5982 | The default key-bindings may be changed with an |
| 5983 | <I>inputrc </I> |
| 5984 | |
| 5985 | file. |
| 5986 | Other programs that use this library may add their own commands |
| 5987 | and bindings. |
| 5988 | <P> |
| 5989 | |
| 5990 | For example, placing |
| 5991 | <DL COMPACT><DT><DD> |
| 5992 | <P> |
| 5993 | |
| 5994 | M-Control-u: universal-argument |
| 5995 | </DL> |
| 5996 | |
| 5997 | or |
| 5998 | <DL COMPACT><DT><DD> |
| 5999 | C-Meta-u: universal-argument |
| 6000 | </DL> |
| 6001 | |
| 6002 | into the |
| 6003 | <I>inputrc</I> |
| 6004 | |
| 6005 | would make M-C-u execute the readline command |
| 6006 | <I>universal-argument</I>. |
| 6007 | |
| 6008 | <P> |
| 6009 | |
| 6010 | The following symbolic character names are recognized: |
| 6011 | <I>RUBOUT</I>, |
| 6012 | |
| 6013 | <I>DEL</I>, |
| 6014 | |
| 6015 | <I>ESC</I>, |
| 6016 | |
| 6017 | <I>LFD</I>, |
| 6018 | |
| 6019 | <I>NEWLINE</I>, |
| 6020 | |
| 6021 | <I>RET</I>, |
| 6022 | |
| 6023 | <I>RETURN</I>, |
| 6024 | |
| 6025 | <I>SPC</I>, |
| 6026 | |
| 6027 | <I>SPACE</I>, |
| 6028 | |
| 6029 | and |
| 6030 | <I>TAB</I>. |
| 6031 | |
| 6032 | <P> |
| 6033 | |
| 6034 | In addition to command names, readline allows keys to be bound |
| 6035 | to a string that is inserted when the key is pressed (a <I>macro</I>). |
| 6036 | <A NAME="lbCI"> </A> |
| 6037 | <H4>Readline Key Bindings</H4> |
| 6038 | |
| 6039 | <P> |
| 6040 | |
| 6041 | The syntax for controlling key bindings in the |
| 6042 | <I>inputrc</I> |
| 6043 | |
| 6044 | file is simple. All that is required is the name of the |
| 6045 | command or the text of a macro and a key sequence to which |
| 6046 | it should be bound. The name may be specified in one of two ways: |
| 6047 | as a symbolic key name, possibly with <I>Meta-</I> or <I>Control-</I> |
| 6048 | prefixes, or as a key sequence. |
| 6049 | <P> |
| 6050 | |
| 6051 | When using the form <B>keyname</B>:<I>function-name</I> or <I>macro</I>, |
| 6052 | <I>keyname</I> |
| 6053 | |
| 6054 | is the name of a key spelled out in English. For example: |
| 6055 | <P> |
| 6056 | <DL COMPACT><DT><DD> |
| 6057 | Control-u: universal-argument |
| 6058 | <BR> |
| 6059 | |
| 6060 | Meta-Rubout: backward-kill-word |
| 6061 | <BR> |
| 6062 | |
| 6063 | Control-o: "> output" |
| 6064 | </DL> |
| 6065 | |
| 6066 | <P> |
| 6067 | |
| 6068 | In the above example, |
| 6069 | <I>C-u</I> |
| 6070 | |
| 6071 | is bound to the function |
| 6072 | <B>universal-argument</B>, |
| 6073 | |
| 6074 | <I>M-DEL</I> |
| 6075 | |
| 6076 | is bound to the function |
| 6077 | <B>backward-kill-word</B>, |
| 6078 | |
| 6079 | and |
| 6080 | <I>C-o</I> |
| 6081 | |
| 6082 | is bound to run the macro |
| 6083 | expressed on the right hand side (that is, to insert the text |
| 6084 | <TT>> output</TT> |
| 6085 | |
| 6086 | into the line). |
| 6087 | <P> |
| 6088 | |
| 6089 | In the second form, <B>"keyseq"</B>:<I>function-name</I> or <I>macro</I>, |
| 6090 | <B>keyseq</B> |
| 6091 | |
| 6092 | differs from |
| 6093 | <B>keyname</B> |
| 6094 | |
| 6095 | above in that strings denoting |
| 6096 | an entire key sequence may be specified by placing the sequence |
| 6097 | within double quotes. Some GNU Emacs style key escapes can be |
| 6098 | used, as in the following example, but the symbolic character names |
| 6099 | are not recognized. |
| 6100 | <P> |
| 6101 | <DL COMPACT><DT><DD> |
| 6102 | "\C-u": universal-argument |
| 6103 | <BR> |
| 6104 | |
| 6105 | "\C-x\C-r": re-read-init-file |
| 6106 | <BR> |
| 6107 | |
| 6108 | "\e[11~": "Function Key 1" |
| 6109 | </DL> |
| 6110 | |
| 6111 | <P> |
| 6112 | |
| 6113 | In this example, |
| 6114 | <I>C-u</I> |
| 6115 | |
| 6116 | is again bound to the function |
| 6117 | <B>universal-argument</B>. |
| 6118 | |
| 6119 | <I>C-x C-r</I> |
| 6120 | |
| 6121 | is bound to the function |
| 6122 | <B>re-read-init-file</B>, |
| 6123 | |
| 6124 | and |
| 6125 | <I>ESC [ 1 1 ~</I> |
| 6126 | |
| 6127 | is bound to insert the text |
| 6128 | <TT>Function Key 1</TT>. |
| 6129 | |
| 6130 | <P> |
| 6131 | |
| 6132 | The full set of GNU Emacs style escape sequences is |
| 6133 | <DL COMPACT><DT><DD> |
| 6134 | |
| 6135 | <DL COMPACT> |
| 6136 | <DT><B>\C-</B> |
| 6137 | |
| 6138 | <DD> |
| 6139 | control prefix |
| 6140 | <DT><B>\M-</B> |
| 6141 | |
| 6142 | <DD> |
| 6143 | meta prefix |
| 6144 | <DT><B>\e</B> |
| 6145 | |
| 6146 | <DD> |
| 6147 | an escape character |
| 6148 | <DT><B>\\</B> |
| 6149 | |
| 6150 | <DD> |
| 6151 | backslash |
| 6152 | <DT><B>\</B> |
| 6153 | |
| 6154 | <DD> |
| 6155 | literal " |
| 6156 | <DT><B>\aq</B> |
| 6157 | |
| 6158 | <DD> |
| 6159 | literal aq |
| 6160 | </DL></DL> |
| 6161 | |
| 6162 | |
| 6163 | <P> |
| 6164 | |
| 6165 | In addition to the GNU Emacs style escape sequences, a second |
| 6166 | set of backslash escapes is available: |
| 6167 | <DL COMPACT><DT><DD> |
| 6168 | |
| 6169 | <DL COMPACT> |
| 6170 | <DT><B>\a</B> |
| 6171 | |
| 6172 | <DD> |
| 6173 | alert (bell) |
| 6174 | <DT><B>\b</B> |
| 6175 | |
| 6176 | <DD> |
| 6177 | backspace |
| 6178 | <DT><B>\d</B> |
| 6179 | |
| 6180 | <DD> |
| 6181 | delete |
| 6182 | <DT><B>\f</B> |
| 6183 | |
| 6184 | <DD> |
| 6185 | form feed |
| 6186 | <DT><B>\n</B> |
| 6187 | |
| 6188 | <DD> |
| 6189 | newline |
| 6190 | <DT><B>\r</B> |
| 6191 | |
| 6192 | <DD> |
| 6193 | carriage return |
| 6194 | <DT><B>\t</B> |
| 6195 | |
| 6196 | <DD> |
| 6197 | horizontal tab |
| 6198 | <DT><B>\v</B> |
| 6199 | |
| 6200 | <DD> |
| 6201 | vertical tab |
| 6202 | <DT><B>\</B><I>nnn</I> |
| 6203 | |
| 6204 | <DD> |
| 6205 | the eight-bit character whose value is the octal value <I>nnn</I> |
| 6206 | (one to three digits) |
| 6207 | <DT><B>\x</B><I>HH</I> |
| 6208 | |
| 6209 | <DD> |
| 6210 | the eight-bit character whose value is the hexadecimal value <I>HH</I> |
| 6211 | (one or two hex digits) |
| 6212 | </DL></DL> |
| 6213 | |
| 6214 | |
| 6215 | <P> |
| 6216 | |
| 6217 | When entering the text of a macro, single or double quotes must |
| 6218 | be used to indicate a macro definition. |
| 6219 | Unquoted text is assumed to be a function name. |
| 6220 | In the macro body, the backslash escapes described above are expanded. |
| 6221 | Backslash will quote any other character in the macro text, |
| 6222 | including " and aq. |
| 6223 | <P> |
| 6224 | |
| 6225 | <B>Bash</B> |
| 6226 | |
| 6227 | allows the current readline key bindings to be displayed or modified |
| 6228 | with the |
| 6229 | <B>bind</B> |
| 6230 | |
| 6231 | builtin command. The editing mode may be switched during interactive |
| 6232 | use by using the |
| 6233 | <B>-o</B> |
| 6234 | |
| 6235 | option to the |
| 6236 | <B>set</B> |
| 6237 | |
| 6238 | builtin command (see |
| 6239 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 6240 | |
| 6241 | </FONT> |
| 6242 | below). |
| 6243 | <A NAME="lbCJ"> </A> |
| 6244 | <H4>Readline Variables</H4> |
| 6245 | |
| 6246 | <P> |
| 6247 | |
| 6248 | Readline has variables that can be used to further customize its |
| 6249 | behavior. A variable may be set in the |
| 6250 | <I>inputrc</I> |
| 6251 | |
| 6252 | file with a statement of the form |
| 6253 | <DL COMPACT><DT><DD> |
| 6254 | <P> |
| 6255 | |
| 6256 | <B>set</B> <I>variable-name</I> <I>value</I> |
| 6257 | </DL> |
| 6258 | |
| 6259 | <P> |
| 6260 | |
| 6261 | Except where noted, readline variables can take the values |
| 6262 | <B>On</B> |
| 6263 | |
| 6264 | or |
| 6265 | <B>Off</B> |
| 6266 | |
| 6267 | (without regard to case). |
| 6268 | Unrecognized variable names are ignored. |
| 6269 | When a variable value is read, empty or null values, "on" (case-insensitive), |
| 6270 | and "1" are equivalent to <B>On</B>. All other values are equivalent to |
| 6271 | <B>Off</B>. |
| 6272 | The variables and their default values are: |
| 6273 | <P> |
| 6274 | |
| 6275 | |
| 6276 | <DL COMPACT> |
| 6277 | <DT><B>bell-style (audible)</B> |
| 6278 | |
| 6279 | <DD> |
| 6280 | Controls what happens when readline wants to ring the terminal bell. |
| 6281 | If set to <B>none</B>, readline never rings the bell. If set to |
| 6282 | <B>visible</B>, readline uses a visible bell if one is available. |
| 6283 | If set to <B>audible</B>, readline attempts to ring the terminal's bell. |
| 6284 | <DT><B>bind-tty-special-chars (On)</B> |
| 6285 | |
| 6286 | <DD> |
| 6287 | If set to <B>On</B>, readline attempts to bind the control characters |
| 6288 | treated specially by the kernel's terminal driver to their readline |
| 6289 | equivalents. |
| 6290 | <DT><B>comment-begin (``#'')</B> |
| 6291 | |
| 6292 | <DD> |
| 6293 | The string that is inserted when the readline |
| 6294 | <B>insert-comment</B> |
| 6295 | |
| 6296 | command is executed. |
| 6297 | This command is bound to |
| 6298 | <B>M-#</B> |
| 6299 | |
| 6300 | in emacs mode and to |
| 6301 | <B>#</B> |
| 6302 | |
| 6303 | in vi command mode. |
| 6304 | <DT><B>completion-ignore-case (Off)</B> |
| 6305 | |
| 6306 | <DD> |
| 6307 | If set to <B>On</B>, readline performs filename matching and completion |
| 6308 | in a case-insensitive fashion. |
| 6309 | <DT><B>completion-prefix-display-length (0)</B> |
| 6310 | |
| 6311 | <DD> |
| 6312 | The length in characters of the common prefix of a list of possible |
| 6313 | completions that is displayed without modification. When set to a |
| 6314 | value greater than zero, common prefixes longer than this value are |
| 6315 | replaced with an ellipsis when displaying possible completions. |
| 6316 | <DT><B>completion-query-items (100)</B> |
| 6317 | |
| 6318 | <DD> |
| 6319 | This determines when the user is queried about viewing |
| 6320 | the number of possible completions |
| 6321 | generated by the <B>possible-completions</B> command. |
| 6322 | It may be set to any integer value greater than or equal to |
| 6323 | zero. If the number of possible completions is greater than |
| 6324 | or equal to the value of this variable, the user is asked whether |
| 6325 | or not he wishes to view them; otherwise they are simply listed |
| 6326 | on the terminal. |
| 6327 | <DT><B>convert-meta (On)</B> |
| 6328 | |
| 6329 | <DD> |
| 6330 | If set to <B>On</B>, readline will convert characters with the |
| 6331 | eighth bit set to an ASCII key sequence |
| 6332 | by stripping the eighth bit and prefixing an |
| 6333 | escape character (in effect, using escape as the <I>meta prefix</I>). |
| 6334 | <DT><B>disable-completion (Off)</B> |
| 6335 | |
| 6336 | <DD> |
| 6337 | If set to <B>On</B>, readline will inhibit word completion. Completion |
| 6338 | characters will be inserted into the line as if they had been |
| 6339 | mapped to <B>self-insert</B>. |
| 6340 | <DT><B>editing-mode (emacs)</B> |
| 6341 | |
| 6342 | <DD> |
| 6343 | Controls whether readline begins with a set of key bindings similar |
| 6344 | to <I>emacs</I> or <I>vi</I>. |
| 6345 | <B>editing-mode</B> |
| 6346 | |
| 6347 | can be set to either |
| 6348 | <B>emacs</B> |
| 6349 | |
| 6350 | or |
| 6351 | <B>vi</B>. |
| 6352 | |
| 6353 | <DT><B>enable-keypad (Off)</B> |
| 6354 | |
| 6355 | <DD> |
| 6356 | When set to <B>On</B>, readline will try to enable the application |
| 6357 | keypad when it is called. Some systems need this to enable the |
| 6358 | arrow keys. |
| 6359 | <DT><B>expand-tilde (Off)</B> |
| 6360 | |
| 6361 | <DD> |
| 6362 | If set to <B>on</B>, tilde expansion is performed when readline |
| 6363 | attempts word completion. |
| 6364 | <DT><B>history-preserve-point (Off)</B> |
| 6365 | |
| 6366 | <DD> |
| 6367 | If set to <B>on</B>, the history code attempts to place point at the |
| 6368 | same location on each history line retrieved with <B>previous-history</B> |
| 6369 | or <B>next-history</B>. |
| 6370 | <DT><B>history-size (0)</B> |
| 6371 | |
| 6372 | <DD> |
| 6373 | Set the maximum number of history entries saved in the history list. If |
| 6374 | set to zero, the number of entries in the history list is not limited. |
| 6375 | <DT><B>horizontal-scroll-mode (Off)</B> |
| 6376 | |
| 6377 | <DD> |
| 6378 | When set to <B>On</B>, makes readline use a single line for display, |
| 6379 | scrolling the input horizontally on a single screen line when it |
| 6380 | becomes longer than the screen width rather than wrapping to a new line. |
| 6381 | <DT><B>input-meta (Off)</B> |
| 6382 | |
| 6383 | <DD> |
| 6384 | If set to <B>On</B>, readline will enable eight-bit input (that is, |
| 6385 | it will not strip the high bit from the characters it reads), |
| 6386 | regardless of what the terminal claims it can support. The name |
| 6387 | <B>meta-flag</B> |
| 6388 | |
| 6389 | is a synonym for this variable. |
| 6390 | <DT><B>isearch-terminators (``C-[C-J'')</B> |
| 6391 | |
| 6392 | <DD> |
| 6393 | The string of characters that should terminate an incremental |
| 6394 | search without subsequently executing the character as a command. |
| 6395 | If this variable has not been given a value, the characters |
| 6396 | <I>ESC</I> and <I>C-J</I> will terminate an incremental search. |
| 6397 | <DT><B>keymap (emacs)</B> |
| 6398 | |
| 6399 | <DD> |
| 6400 | Set the current readline keymap. The set of valid keymap names is |
| 6401 | <I>emacs, emacs-standard, emacs-meta, emacs-ctlx, vi, |
| 6402 | vi-command</I>, and |
| 6403 | <I>vi-insert</I>. |
| 6404 | |
| 6405 | <I>vi</I> is equivalent to <I>vi-command</I>; <I>emacs</I> is |
| 6406 | equivalent to <I>emacs-standard</I>. The default value is |
| 6407 | <I>emacs</I>; |
| 6408 | |
| 6409 | the value of |
| 6410 | <B>editing-mode</B> |
| 6411 | |
| 6412 | also affects the default keymap. |
| 6413 | <DT><B>mark-directories (On)</B> |
| 6414 | |
| 6415 | <DD> |
| 6416 | If set to <B>On</B>, completed directory names have a slash |
| 6417 | appended. |
| 6418 | <DT><B>mark-modified-lines (Off)</B> |
| 6419 | |
| 6420 | <DD> |
| 6421 | If set to <B>On</B>, history lines that have been modified are displayed |
| 6422 | with a preceding asterisk (<B>*</B>). |
| 6423 | <DT><B>mark-symlinked-directories (Off)</B> |
| 6424 | |
| 6425 | <DD> |
| 6426 | If set to <B>On</B>, completed names which are symbolic links to directories |
| 6427 | have a slash appended (subject to the value of |
| 6428 | <B>mark-directories</B>). |
| 6429 | <DT><B>match-hidden-files (On)</B> |
| 6430 | |
| 6431 | <DD> |
| 6432 | This variable, when set to <B>On</B>, causes readline to match files whose |
| 6433 | names begin with a `.' (hidden files) when performing filename |
| 6434 | completion, unless the leading `.' is |
| 6435 | supplied by the user in the filename to be completed. |
| 6436 | <DT><B>output-meta (Off)</B> |
| 6437 | |
| 6438 | <DD> |
| 6439 | If set to <B>On</B>, readline will display characters with the |
| 6440 | eighth bit set directly rather than as a meta-prefixed escape |
| 6441 | sequence. |
| 6442 | <DT><B>page-completions (On)</B> |
| 6443 | |
| 6444 | <DD> |
| 6445 | If set to <B>On</B>, readline uses an internal <I>more</I>-like pager |
| 6446 | to display a screenful of possible completions at a time. |
| 6447 | <DT><B>print-completions-horizontally (Off)</B> |
| 6448 | |
| 6449 | <DD> |
| 6450 | If set to <B>On</B>, readline will display completions with matches |
| 6451 | sorted horizontally in alphabetical order, rather than down the screen. |
| 6452 | <DT><B>revert-all-at-newline (Off)</B> |
| 6453 | |
| 6454 | <DD> |
| 6455 | If set to <B>on</B>, readline will undo all changes to history lines |
| 6456 | before returning when <B>accept-line</B> is executed. By default, |
| 6457 | history lines may be modified and retain individual undo lists across |
| 6458 | calls to <B>readline</B>. |
| 6459 | <DT><B>show-all-if-ambiguous (Off)</B> |
| 6460 | |
| 6461 | <DD> |
| 6462 | This alters the default behavior of the completion functions. If |
| 6463 | set to |
| 6464 | <B>on</B>, |
| 6465 | |
| 6466 | words which have more than one possible completion cause the |
| 6467 | matches to be listed immediately instead of ringing the bell. |
| 6468 | <DT><B>show-all-if-unmodified (Off)</B> |
| 6469 | |
| 6470 | <DD> |
| 6471 | This alters the default behavior of the completion functions in |
| 6472 | a fashion similar to <B>show-all-if-ambiguous</B>. |
| 6473 | If set to |
| 6474 | <B>on</B>, |
| 6475 | |
| 6476 | words which have more than one possible completion without any |
| 6477 | possible partial completion (the possible completions don't share |
| 6478 | a common prefix) cause the matches to be listed immediately instead |
| 6479 | of ringing the bell. |
| 6480 | <DT><B>visible-stats (Off)</B> |
| 6481 | |
| 6482 | <DD> |
| 6483 | If set to <B>On</B>, a character denoting a file's type as reported |
| 6484 | by <I>stat</I>(2) is appended to the filename when listing possible |
| 6485 | completions. |
| 6486 | |
| 6487 | </DL> |
| 6488 | <A NAME="lbCK"> </A> |
| 6489 | <H4>Readline Conditional Constructs</H4> |
| 6490 | |
| 6491 | <P> |
| 6492 | |
| 6493 | Readline implements a facility similar in spirit to the conditional |
| 6494 | compilation features of the C preprocessor which allows key |
| 6495 | bindings and variable settings to be performed as the result |
| 6496 | of tests. There are four parser directives used. |
| 6497 | <DL COMPACT> |
| 6498 | <DT><B>$if</B><DD> |
| 6499 | The |
| 6500 | <B>$if</B> |
| 6501 | |
| 6502 | construct allows bindings to be made based on the |
| 6503 | editing mode, the terminal being used, or the application using |
| 6504 | readline. The text of the test extends to the end of the line; |
| 6505 | no characters are required to isolate it. |
| 6506 | <DL COMPACT><DT><DD> |
| 6507 | <DL COMPACT> |
| 6508 | <DT><B>mode</B><DD> |
| 6509 | The <B>mode=</B> form of the <B>$if</B> directive is used to test |
| 6510 | whether readline is in emacs or vi mode. |
| 6511 | This may be used in conjunction |
| 6512 | with the <B>set keymap</B> command, for instance, to set bindings in |
| 6513 | the <I>emacs-standard</I> and <I>emacs-ctlx</I> keymaps only if |
| 6514 | readline is starting out in emacs mode. |
| 6515 | <DT><B>term</B><DD> |
| 6516 | The <B>term=</B> form may be used to include terminal-specific |
| 6517 | key bindings, perhaps to bind the key sequences output by the |
| 6518 | terminal's function keys. The word on the right side of the |
| 6519 | <B>=</B> |
| 6520 | |
| 6521 | is tested against the both full name of the terminal and the portion |
| 6522 | of the terminal name before the first <B>-</B>. This allows |
| 6523 | <I>sun</I> |
| 6524 | |
| 6525 | to match both |
| 6526 | <I>sun</I> |
| 6527 | |
| 6528 | and |
| 6529 | <I>sun-cmd</I>, |
| 6530 | |
| 6531 | for instance. |
| 6532 | <DT><B>application</B><DD> |
| 6533 | The <B>application</B> construct is used to include |
| 6534 | application-specific settings. Each program using the readline |
| 6535 | library sets the <I>application name</I>, and an initialization |
| 6536 | file can test for a particular value. |
| 6537 | This could be used to bind key sequences to functions useful for |
| 6538 | a specific program. For instance, the following command adds a |
| 6539 | key sequence that quotes the current or previous word in Bash: |
| 6540 | <P> |
| 6541 | <DL COMPACT><DT><DD> |
| 6542 | <PRE> |
| 6543 | <B>$if</B> Bash |
| 6544 | # Quote the current or previous word |
| 6545 | "\C-xq": "\eb\"\ef\"" |
| 6546 | <B>$endif</B> |
| 6547 | </PRE> |
| 6548 | |
| 6549 | </DL> |
| 6550 | |
| 6551 | </DL></DL> |
| 6552 | |
| 6553 | <DT><B>$endif</B><DD> |
| 6554 | This command, as seen in the previous example, terminates an |
| 6555 | <B>$if</B> command. |
| 6556 | <DT><B>$else</B><DD> |
| 6557 | Commands in this branch of the <B>$if</B> directive are executed if |
| 6558 | the test fails. |
| 6559 | <DT><B>$include</B><DD> |
| 6560 | This directive takes a single filename as an argument and reads commands |
| 6561 | and bindings from that file. For example, the following directive |
| 6562 | would read <A HREF="file:/etc/inputrc"><I>/etc/inputrc</I></A>: |
| 6563 | <P> |
| 6564 | <DL COMPACT><DT><DD> |
| 6565 | <PRE> |
| 6566 | <B>$include</B> <A HREF="file:/etc/inputrc"><I>/etc/inputrc</I></A> |
| 6567 | </PRE> |
| 6568 | |
| 6569 | </DL> |
| 6570 | |
| 6571 | </DL> |
| 6572 | <A NAME="lbCL"> </A> |
| 6573 | <H4>Searching</H4> |
| 6574 | |
| 6575 | <P> |
| 6576 | |
| 6577 | Readline provides commands for searching through the command history |
| 6578 | (see |
| 6579 | <FONT SIZE=-1><B>HISTORY</B> |
| 6580 | |
| 6581 | </FONT> |
| 6582 | below) for lines containing a specified string. |
| 6583 | There are two search modes: |
| 6584 | <I>incremental</I> |
| 6585 | |
| 6586 | and |
| 6587 | <I>non-incremental</I>. |
| 6588 | |
| 6589 | <P> |
| 6590 | |
| 6591 | Incremental searches begin before the user has finished typing the |
| 6592 | search string. |
| 6593 | As each character of the search string is typed, readline displays |
| 6594 | the next entry from the history matching the string typed so far. |
| 6595 | An incremental search requires only as many characters as needed to |
| 6596 | find the desired history entry. |
| 6597 | The characters present in the value of the <B>isearch-terminators</B> |
| 6598 | variable are used to terminate an incremental search. |
| 6599 | If that variable has not been assigned a value the Escape and |
| 6600 | Control-J characters will terminate an incremental search. |
| 6601 | Control-G will abort an incremental search and restore the original |
| 6602 | line. |
| 6603 | When the search is terminated, the history entry containing the |
| 6604 | search string becomes the current line. |
| 6605 | <P> |
| 6606 | |
| 6607 | To find other matching entries in the history list, type Control-S or |
| 6608 | Control-R as appropriate. |
| 6609 | This will search backward or forward in the history for the next |
| 6610 | entry matching the search string typed so far. |
| 6611 | Any other key sequence bound to a readline command will terminate |
| 6612 | the search and execute that command. |
| 6613 | For instance, a <I>newline</I> will terminate the search and accept |
| 6614 | the line, thereby executing the command from the history list. |
| 6615 | <P> |
| 6616 | |
| 6617 | Readline remembers the last incremental search string. If two |
| 6618 | Control-Rs are typed without any intervening characters defining a |
| 6619 | new search string, any remembered search string is used. |
| 6620 | <P> |
| 6621 | |
| 6622 | Non-incremental searches read the entire search string before starting |
| 6623 | to search for matching history lines. The search string may be |
| 6624 | typed by the user or be part of the contents of the current line. |
| 6625 | <A NAME="lbCM"> </A> |
| 6626 | <H4>Readline Command Names</H4> |
| 6627 | |
| 6628 | <P> |
| 6629 | |
| 6630 | The following is a list of the names of the commands and the default |
| 6631 | key sequences to which they are bound. |
| 6632 | Command names without an accompanying key sequence are unbound by default. |
| 6633 | In the following descriptions, <I>point</I> refers to the current cursor |
| 6634 | position, and <I>mark</I> refers to a cursor position saved by the |
| 6635 | <B>set-mark</B> command. |
| 6636 | The text between the point and mark is referred to as the <I>region</I>. |
| 6637 | <A NAME="lbCN"> </A> |
| 6638 | <H4>Commands for Moving</H4> |
| 6639 | |
| 6640 | <P> |
| 6641 | |
| 6642 | |
| 6643 | <DL COMPACT> |
| 6644 | <DT><B>beginning-of-line (C-a)</B> |
| 6645 | |
| 6646 | <DD> |
| 6647 | Move to the start of the current line. |
| 6648 | <DT><B>end-of-line (C-e)</B> |
| 6649 | |
| 6650 | <DD> |
| 6651 | Move to the end of the line. |
| 6652 | <DT><B>forward-char (C-f)</B> |
| 6653 | |
| 6654 | <DD> |
| 6655 | Move forward a character. |
| 6656 | <DT><B>backward-char (C-b)</B> |
| 6657 | |
| 6658 | <DD> |
| 6659 | Move back a character. |
| 6660 | <DT><B>forward-word (M-f)</B> |
| 6661 | |
| 6662 | <DD> |
| 6663 | Move forward to the end of the next word. Words are composed of |
| 6664 | alphanumeric characters (letters and digits). |
| 6665 | <DT><B>backward-word (M-b)</B> |
| 6666 | |
| 6667 | <DD> |
| 6668 | Move back to the start of the current or previous word. |
| 6669 | Words are composed of alphanumeric characters (letters and digits). |
| 6670 | <DT><B>shell-forward-word</B> |
| 6671 | |
| 6672 | <DD> |
| 6673 | Move forward to the end of the next word. |
| 6674 | Words are delimited by non-quoted shell metacharacters. |
| 6675 | <DT><B>shell-backward-word</B> |
| 6676 | |
| 6677 | <DD> |
| 6678 | Move back to the start of the current or previous word. |
| 6679 | Words are delimited by non-quoted shell metacharacters. |
| 6680 | <DT><B>clear-screen (C-l)</B> |
| 6681 | |
| 6682 | <DD> |
| 6683 | Clear the screen leaving the current line at the top of the screen. |
| 6684 | With an argument, refresh the current line without clearing the |
| 6685 | screen. |
| 6686 | <DT><B>redraw-current-line</B> |
| 6687 | |
| 6688 | <DD> |
| 6689 | Refresh the current line. |
| 6690 | |
| 6691 | </DL> |
| 6692 | <A NAME="lbCO"> </A> |
| 6693 | <H4>Commands for Manipulating the History</H4> |
| 6694 | |
| 6695 | <P> |
| 6696 | |
| 6697 | |
| 6698 | <DL COMPACT> |
| 6699 | <DT><B>accept-line (Newline, Return)</B> |
| 6700 | |
| 6701 | <DD> |
| 6702 | Accept the line regardless of where the cursor is. If this line is |
| 6703 | non-empty, add it to the history list according to the state of the |
| 6704 | <FONT SIZE=-1><B>HISTCONTROL</B> |
| 6705 | |
| 6706 | </FONT> |
| 6707 | variable. If the line is a modified history |
| 6708 | line, then restore the history line to its original state. |
| 6709 | <DT><B>previous-history (C-p)</B> |
| 6710 | |
| 6711 | <DD> |
| 6712 | Fetch the previous command from the history list, moving back in |
| 6713 | the list. |
| 6714 | <DT><B>next-history (C-n)</B> |
| 6715 | |
| 6716 | <DD> |
| 6717 | Fetch the next command from the history list, moving forward in the |
| 6718 | list. |
| 6719 | <DT><B>beginning-of-history (M-<)</B> |
| 6720 | |
| 6721 | <DD> |
| 6722 | Move to the first line in the history. |
| 6723 | <DT><B>end-of-history (M->)</B> |
| 6724 | |
| 6725 | <DD> |
| 6726 | Move to the end of the input history, i.e., the line currently being |
| 6727 | entered. |
| 6728 | <DT><B>reverse-search-history (C-r)</B> |
| 6729 | |
| 6730 | <DD> |
| 6731 | Search backward starting at the current line and moving `up' through |
| 6732 | the history as necessary. This is an incremental search. |
| 6733 | <DT><B>forward-search-history (C-s)</B> |
| 6734 | |
| 6735 | <DD> |
| 6736 | Search forward starting at the current line and moving `down' through |
| 6737 | the history as necessary. This is an incremental search. |
| 6738 | <DT><B>non-incremental-reverse-search-history (M-p)</B> |
| 6739 | |
| 6740 | <DD> |
| 6741 | Search backward through the history starting at the current line |
| 6742 | using a non-incremental search for a string supplied by the user. |
| 6743 | <DT><B>non-incremental-forward-search-history (M-n)</B> |
| 6744 | |
| 6745 | <DD> |
| 6746 | Search forward through the history using a non-incremental search for |
| 6747 | a string supplied by the user. |
| 6748 | <DT><B>history-search-forward</B> |
| 6749 | |
| 6750 | <DD> |
| 6751 | Search forward through the history for the string of characters |
| 6752 | between the start of the current line and the point. |
| 6753 | This is a non-incremental search. |
| 6754 | <DT><B>history-search-backward</B> |
| 6755 | |
| 6756 | <DD> |
| 6757 | Search backward through the history for the string of characters |
| 6758 | between the start of the current line and the point. |
| 6759 | This is a non-incremental search. |
| 6760 | <DT><B>yank-nth-arg (M-C-y)</B> |
| 6761 | |
| 6762 | <DD> |
| 6763 | Insert the first argument to the previous command (usually |
| 6764 | the second word on the previous line) at point. |
| 6765 | With an argument |
| 6766 | <I>n</I>, |
| 6767 | |
| 6768 | insert the <I>n</I>th word from the previous command (the words |
| 6769 | in the previous command begin with word 0). A negative argument |
| 6770 | inserts the <I>n</I>th word from the end of the previous command. |
| 6771 | Once the argument <I>n</I> is computed, the argument is extracted |
| 6772 | as if the "!<I>n</I>" history expansion had been specified. |
| 6773 | <DT><B>yank-last-arg (M-., M-_)</B> |
| 6774 | |
| 6775 | <DD> |
| 6776 | Insert the last argument to the previous command (the last word of |
| 6777 | the previous history entry). With an argument, |
| 6778 | behave exactly like <B>yank-nth-arg</B>. |
| 6779 | Successive calls to <B>yank-last-arg</B> move back through the history |
| 6780 | list, inserting the last argument of each line in turn. |
| 6781 | The history expansion facilities are used to extract the last argument, |
| 6782 | as if the "!$" history expansion had been specified. |
| 6783 | <DT><B>shell-expand-line (M-C-e)</B> |
| 6784 | |
| 6785 | <DD> |
| 6786 | Expand the line as the shell does. This |
| 6787 | performs alias and history expansion as well as all of the shell |
| 6788 | word expansions. See |
| 6789 | <FONT SIZE=-1><B>HISTORY EXPANSION</B> |
| 6790 | |
| 6791 | </FONT> |
| 6792 | below for a description of history expansion. |
| 6793 | <DT><B>history-expand-line (M-^)</B> |
| 6794 | |
| 6795 | <DD> |
| 6796 | Perform history expansion on the current line. |
| 6797 | See |
| 6798 | <FONT SIZE=-1><B>HISTORY EXPANSION</B> |
| 6799 | |
| 6800 | </FONT> |
| 6801 | below for a description of history expansion. |
| 6802 | <DT><B>magic-space</B> |
| 6803 | |
| 6804 | <DD> |
| 6805 | Perform history expansion on the current line and insert a space. |
| 6806 | See |
| 6807 | <FONT SIZE=-1><B>HISTORY EXPANSION</B> |
| 6808 | |
| 6809 | </FONT> |
| 6810 | below for a description of history expansion. |
| 6811 | <DT><B>alias-expand-line</B> |
| 6812 | |
| 6813 | <DD> |
| 6814 | Perform alias expansion on the current line. |
| 6815 | See |
| 6816 | <FONT SIZE=-1><B>ALIASES</B> |
| 6817 | |
| 6818 | </FONT> |
| 6819 | above for a description of alias expansion. |
| 6820 | <DT><B>history-and-alias-expand-line</B> |
| 6821 | |
| 6822 | <DD> |
| 6823 | Perform history and alias expansion on the current line. |
| 6824 | <DT><B>insert-last-argument (M-., M-_)</B> |
| 6825 | |
| 6826 | <DD> |
| 6827 | A synonym for <B>yank-last-arg</B>. |
| 6828 | <DT><B>operate-and-get-next (C-o)</B> |
| 6829 | |
| 6830 | <DD> |
| 6831 | Accept the current line for execution and fetch the next line |
| 6832 | relative to the current line from the history for editing. Any |
| 6833 | argument is ignored. |
| 6834 | <DT><B>edit-and-execute-command (C-xC-e)</B> |
| 6835 | |
| 6836 | <DD> |
| 6837 | Invoke an editor on the current command line, and execute the result as shell |
| 6838 | commands. |
| 6839 | <B>Bash</B> attempts to invoke |
| 6840 | <FONT SIZE=-1><B>$VISUAL</B>, |
| 6841 | |
| 6842 | </FONT> |
| 6843 | <FONT SIZE=-1><B>$EDITOR</B>, |
| 6844 | |
| 6845 | </FONT> |
| 6846 | and <I>emacs</I> as the editor, in that order. |
| 6847 | |
| 6848 | </DL> |
| 6849 | <A NAME="lbCP"> </A> |
| 6850 | <H4>Commands for Changing Text</H4> |
| 6851 | |
| 6852 | <P> |
| 6853 | |
| 6854 | |
| 6855 | <DL COMPACT> |
| 6856 | <DT><B>delete-char (C-d)</B> |
| 6857 | |
| 6858 | <DD> |
| 6859 | Delete the character at point. If point is at the |
| 6860 | beginning of the line, there are no characters in the line, and |
| 6861 | the last character typed was not bound to <B>delete-char</B>, |
| 6862 | then return |
| 6863 | <FONT SIZE=-1><B>EOF</B>. |
| 6864 | |
| 6865 | </FONT> |
| 6866 | <DT><B>backward-delete-char (Rubout)</B> |
| 6867 | |
| 6868 | <DD> |
| 6869 | Delete the character behind the cursor. When given a numeric argument, |
| 6870 | save the deleted text on the kill ring. |
| 6871 | <DT><B>forward-backward-delete-char</B> |
| 6872 | |
| 6873 | <DD> |
| 6874 | Delete the character under the cursor, unless the cursor is at the |
| 6875 | end of the line, in which case the character behind the cursor is |
| 6876 | deleted. |
| 6877 | <DT><B>quoted-insert (C-q, C-v)</B> |
| 6878 | |
| 6879 | <DD> |
| 6880 | Add the next character typed to the line verbatim. This is |
| 6881 | how to insert characters like <B>C-q</B>, for example. |
| 6882 | <DT><B>tab-insert (C-v TAB)</B> |
| 6883 | |
| 6884 | <DD> |
| 6885 | Insert a tab character. |
| 6886 | <DT><B>self-insert (a, b, A, 1, !, ...)</B> |
| 6887 | |
| 6888 | <DD> |
| 6889 | Insert the character typed. |
| 6890 | <DT><B>transpose-chars (C-t)</B> |
| 6891 | |
| 6892 | <DD> |
| 6893 | Drag the character before point forward over the character at point, |
| 6894 | moving point forward as well. |
| 6895 | If point is at the end of the line, then this transposes |
| 6896 | the two characters before point. |
| 6897 | Negative arguments have no effect. |
| 6898 | <DT><B>transpose-words (M-t)</B> |
| 6899 | |
| 6900 | <DD> |
| 6901 | Drag the word before point past the word after point, |
| 6902 | moving point over that word as well. |
| 6903 | If point is at the end of the line, this transposes |
| 6904 | the last two words on the line. |
| 6905 | <DT><B>upcase-word (M-u)</B> |
| 6906 | |
| 6907 | <DD> |
| 6908 | Uppercase the current (or following) word. With a negative argument, |
| 6909 | uppercase the previous word, but do not move point. |
| 6910 | <DT><B>downcase-word (M-l)</B> |
| 6911 | |
| 6912 | <DD> |
| 6913 | Lowercase the current (or following) word. With a negative argument, |
| 6914 | lowercase the previous word, but do not move point. |
| 6915 | <DT><B>capitalize-word (M-c)</B> |
| 6916 | |
| 6917 | <DD> |
| 6918 | Capitalize the current (or following) word. With a negative argument, |
| 6919 | capitalize the previous word, but do not move point. |
| 6920 | <DT><B>overwrite-mode</B> |
| 6921 | |
| 6922 | <DD> |
| 6923 | Toggle overwrite mode. With an explicit positive numeric argument, |
| 6924 | switches to overwrite mode. With an explicit non-positive numeric |
| 6925 | argument, switches to insert mode. This command affects only |
| 6926 | <B>emacs</B> mode; <B>vi</B> mode does overwrite differently. |
| 6927 | Each call to <I>readline()</I> starts in insert mode. |
| 6928 | In overwrite mode, characters bound to <B>self-insert</B> replace |
| 6929 | the text at point rather than pushing the text to the right. |
| 6930 | Characters bound to <B>backward-delete-char</B> replace the character |
| 6931 | before point with a space. By default, this command is unbound. |
| 6932 | |
| 6933 | </DL> |
| 6934 | <A NAME="lbCQ"> </A> |
| 6935 | <H4>Killing and Yanking</H4> |
| 6936 | |
| 6937 | <P> |
| 6938 | |
| 6939 | |
| 6940 | <DL COMPACT> |
| 6941 | <DT><B>kill-line (C-k)</B> |
| 6942 | |
| 6943 | <DD> |
| 6944 | Kill the text from point to the end of the line. |
| 6945 | <DT><B>backward-kill-line (C-x Rubout)</B> |
| 6946 | |
| 6947 | <DD> |
| 6948 | Kill backward to the beginning of the line. |
| 6949 | <DT><B>unix-line-discard (C-u)</B> |
| 6950 | |
| 6951 | <DD> |
| 6952 | Kill backward from point to the beginning of the line. |
| 6953 | The killed text is saved on the kill-ring. |
| 6954 | |
| 6955 | <DT><B>kill-whole-line</B> |
| 6956 | |
| 6957 | <DD> |
| 6958 | Kill all characters on the current line, no matter where point is. |
| 6959 | <DT><B>kill-word (M-d)</B> |
| 6960 | |
| 6961 | <DD> |
| 6962 | Kill from point to the end of the current word, or if between |
| 6963 | words, to the end of the next word. |
| 6964 | Word boundaries are the same as those used by <B>forward-word</B>. |
| 6965 | <DT><B>backward-kill-word (M-Rubout)</B> |
| 6966 | |
| 6967 | <DD> |
| 6968 | Kill the word behind point. |
| 6969 | Word boundaries are the same as those used by <B>backward-word</B>. |
| 6970 | <DT><B>shell-kill-word (M-d)</B> |
| 6971 | |
| 6972 | <DD> |
| 6973 | Kill from point to the end of the current word, or if between |
| 6974 | words, to the end of the next word. |
| 6975 | Word boundaries are the same as those used by <B>shell-forward-word</B>. |
| 6976 | <DT><B>shell-backward-kill-word (M-Rubout)</B> |
| 6977 | |
| 6978 | <DD> |
| 6979 | Kill the word behind point. |
| 6980 | Word boundaries are the same as those used by <B>shell-backward-word</B>. |
| 6981 | <DT><B>unix-word-rubout (C-w)</B> |
| 6982 | |
| 6983 | <DD> |
| 6984 | Kill the word behind point, using white space as a word boundary. |
| 6985 | The killed text is saved on the kill-ring. |
| 6986 | <DT><B>unix-filename-rubout</B> |
| 6987 | |
| 6988 | <DD> |
| 6989 | Kill the word behind point, using white space and the slash character |
| 6990 | as the word boundaries. |
| 6991 | The killed text is saved on the kill-ring. |
| 6992 | <DT><B>delete-horizontal-space (M-\)</B> |
| 6993 | |
| 6994 | <DD> |
| 6995 | Delete all spaces and tabs around point. |
| 6996 | <DT><B>kill-region</B> |
| 6997 | |
| 6998 | <DD> |
| 6999 | Kill the text in the current region. |
| 7000 | <DT><B>copy-region-as-kill</B> |
| 7001 | |
| 7002 | <DD> |
| 7003 | Copy the text in the region to the kill buffer. |
| 7004 | <DT><B>copy-backward-word</B> |
| 7005 | |
| 7006 | <DD> |
| 7007 | Copy the word before point to the kill buffer. |
| 7008 | The word boundaries are the same as <B>backward-word</B>. |
| 7009 | <DT><B>copy-forward-word</B> |
| 7010 | |
| 7011 | <DD> |
| 7012 | Copy the word following point to the kill buffer. |
| 7013 | The word boundaries are the same as <B>forward-word</B>. |
| 7014 | <DT><B>yank (C-y)</B> |
| 7015 | |
| 7016 | <DD> |
| 7017 | Yank the top of the kill ring into the buffer at point. |
| 7018 | <DT><B>yank-pop (M-y)</B> |
| 7019 | |
| 7020 | <DD> |
| 7021 | Rotate the kill ring, and yank the new top. Only works following |
| 7022 | <B>yank</B> |
| 7023 | |
| 7024 | or |
| 7025 | <B>yank-pop</B>. |
| 7026 | |
| 7027 | |
| 7028 | </DL> |
| 7029 | <A NAME="lbCR"> </A> |
| 7030 | <H4>Numeric Arguments</H4> |
| 7031 | |
| 7032 | <P> |
| 7033 | |
| 7034 | |
| 7035 | <DL COMPACT> |
| 7036 | <DT><B>digit-argument (M-0, M-1, ..., M--)</B> |
| 7037 | |
| 7038 | <DD> |
| 7039 | Add this digit to the argument already accumulating, or start a new |
| 7040 | argument. M-- starts a negative argument. |
| 7041 | <DT><B>universal-argument</B> |
| 7042 | |
| 7043 | <DD> |
| 7044 | This is another way to specify an argument. |
| 7045 | If this command is followed by one or more digits, optionally with a |
| 7046 | leading minus sign, those digits define the argument. |
| 7047 | If the command is followed by digits, executing |
| 7048 | <B>universal-argument</B> |
| 7049 | |
| 7050 | again ends the numeric argument, but is otherwise ignored. |
| 7051 | As a special case, if this command is immediately followed by a |
| 7052 | character that is neither a digit or minus sign, the argument count |
| 7053 | for the next command is multiplied by four. |
| 7054 | The argument count is initially one, so executing this function the |
| 7055 | first time makes the argument count four, a second time makes the |
| 7056 | argument count sixteen, and so on. |
| 7057 | |
| 7058 | </DL> |
| 7059 | <A NAME="lbCS"> </A> |
| 7060 | <H4>Completing</H4> |
| 7061 | |
| 7062 | <P> |
| 7063 | |
| 7064 | |
| 7065 | <DL COMPACT> |
| 7066 | <DT><B>complete (TAB)</B> |
| 7067 | |
| 7068 | <DD> |
| 7069 | Attempt to perform completion on the text before point. |
| 7070 | <B>Bash</B> |
| 7071 | |
| 7072 | attempts completion treating the text as a variable (if the |
| 7073 | text begins with <B>$</B>), username (if the text begins with |
| 7074 | <B>~</B>), hostname (if the text begins with <B>@</B>), or |
| 7075 | command (including aliases and functions) in turn. If none |
| 7076 | of these produces a match, filename completion is attempted. |
| 7077 | <DT><B>possible-completions (M-?)</B> |
| 7078 | |
| 7079 | <DD> |
| 7080 | List the possible completions of the text before point. |
| 7081 | <DT><B>insert-completions (M-*)</B> |
| 7082 | |
| 7083 | <DD> |
| 7084 | Insert all completions of the text before point |
| 7085 | that would have been generated by |
| 7086 | <B>possible-completions</B>. |
| 7087 | <DT><B>menu-complete</B> |
| 7088 | |
| 7089 | <DD> |
| 7090 | Similar to <B>complete</B>, but replaces the word to be completed |
| 7091 | with a single match from the list of possible completions. |
| 7092 | Repeated execution of <B>menu-complete</B> steps through the list |
| 7093 | of possible completions, inserting each match in turn. |
| 7094 | At the end of the list of completions, the bell is rung |
| 7095 | (subject to the setting of <B>bell-style</B>) |
| 7096 | and the original text is restored. |
| 7097 | An argument of <I>n</I> moves <I>n</I> positions forward in the list |
| 7098 | of matches; a negative argument may be used to move backward |
| 7099 | through the list. |
| 7100 | This command is intended to be bound to <B>TAB</B>, but is unbound |
| 7101 | by default. |
| 7102 | <DT><B>delete-char-or-list</B> |
| 7103 | |
| 7104 | <DD> |
| 7105 | Deletes the character under the cursor if not at the beginning or |
| 7106 | end of the line (like <B>delete-char</B>). |
| 7107 | If at the end of the line, behaves identically to |
| 7108 | <B>possible-completions</B>. |
| 7109 | This command is unbound by default. |
| 7110 | <DT><B>complete-filename (M-/)</B> |
| 7111 | |
| 7112 | <DD> |
| 7113 | Attempt filename completion on the text before point. |
| 7114 | <DT><B>possible-filename-completions (C-x /)</B> |
| 7115 | |
| 7116 | <DD> |
| 7117 | List the possible completions of the text before point, |
| 7118 | treating it as a filename. |
| 7119 | <DT><B>complete-username (M-~)</B> |
| 7120 | |
| 7121 | <DD> |
| 7122 | Attempt completion on the text before point, treating |
| 7123 | it as a username. |
| 7124 | <DT><B>possible-username-completions (C-x ~)</B> |
| 7125 | |
| 7126 | <DD> |
| 7127 | List the possible completions of the text before point, |
| 7128 | treating it as a username. |
| 7129 | <DT><B>complete-variable (M-$)</B> |
| 7130 | |
| 7131 | <DD> |
| 7132 | Attempt completion on the text before point, treating |
| 7133 | it as a shell variable. |
| 7134 | <DT><B>possible-variable-completions (C-x $)</B> |
| 7135 | |
| 7136 | <DD> |
| 7137 | List the possible completions of the text before point, |
| 7138 | treating it as a shell variable. |
| 7139 | <DT><B>complete-hostname (M-@)</B> |
| 7140 | |
| 7141 | <DD> |
| 7142 | Attempt completion on the text before point, treating |
| 7143 | it as a hostname. |
| 7144 | <DT><B>possible-hostname-completions (C-x @)</B> |
| 7145 | |
| 7146 | <DD> |
| 7147 | List the possible completions of the text before point, |
| 7148 | treating it as a hostname. |
| 7149 | <DT><B>complete-command (M-!)</B> |
| 7150 | |
| 7151 | <DD> |
| 7152 | Attempt completion on the text before point, treating |
| 7153 | it as a command name. Command completion attempts to |
| 7154 | match the text against aliases, reserved words, shell |
| 7155 | functions, shell builtins, and finally executable filenames, |
| 7156 | in that order. |
| 7157 | <DT><B>possible-command-completions (C-x !)</B> |
| 7158 | |
| 7159 | <DD> |
| 7160 | List the possible completions of the text before point, |
| 7161 | treating it as a command name. |
| 7162 | <DT><B>dynamic-complete-history (M-TAB)</B> |
| 7163 | |
| 7164 | <DD> |
| 7165 | Attempt completion on the text before point, comparing |
| 7166 | the text against lines from the history list for possible |
| 7167 | completion matches. |
| 7168 | <DT><B>dabbrev-expand</B> |
| 7169 | |
| 7170 | <DD> |
| 7171 | Attempt menu completion on the text before point, comparing |
| 7172 | the text against lines from the history list for possible |
| 7173 | completion matches. |
| 7174 | <DT><B>complete-into-braces (M-{)</B> |
| 7175 | |
| 7176 | <DD> |
| 7177 | Perform filename completion and insert the list of possible completions |
| 7178 | enclosed within braces so the list is available to the shell (see |
| 7179 | <B>Brace Expansion</B> |
| 7180 | |
| 7181 | above). |
| 7182 | |
| 7183 | </DL> |
| 7184 | <A NAME="lbCT"> </A> |
| 7185 | <H4>Keyboard Macros</H4> |
| 7186 | |
| 7187 | <P> |
| 7188 | |
| 7189 | |
| 7190 | <DL COMPACT> |
| 7191 | <DT><B>start-kbd-macro (C-x ()</B> |
| 7192 | |
| 7193 | <DD> |
| 7194 | Begin saving the characters typed into the current keyboard macro. |
| 7195 | <DT><B>end-kbd-macro (C-x ))</B> |
| 7196 | |
| 7197 | <DD> |
| 7198 | Stop saving the characters typed into the current keyboard macro |
| 7199 | and store the definition. |
| 7200 | <DT><B>call-last-kbd-macro (C-x e)</B> |
| 7201 | |
| 7202 | <DD> |
| 7203 | Re-execute the last keyboard macro defined, by making the characters |
| 7204 | in the macro appear as if typed at the keyboard. |
| 7205 | |
| 7206 | </DL> |
| 7207 | <A NAME="lbCU"> </A> |
| 7208 | <H4>Miscellaneous</H4> |
| 7209 | |
| 7210 | <P> |
| 7211 | |
| 7212 | |
| 7213 | <DL COMPACT> |
| 7214 | <DT><B>re-read-init-file (C-x C-r)</B> |
| 7215 | |
| 7216 | <DD> |
| 7217 | Read in the contents of the <I>inputrc</I> file, and incorporate |
| 7218 | any bindings or variable assignments found there. |
| 7219 | <DT><B>abort (C-g)</B> |
| 7220 | |
| 7221 | <DD> |
| 7222 | Abort the current editing command and |
| 7223 | ring the terminal's bell (subject to the setting of |
| 7224 | <B>bell-style</B>). |
| 7225 | |
| 7226 | <DT><B>do-uppercase-version (M-a, M-b, M-</B><I>x</I>, ...) |
| 7227 | |
| 7228 | <DD> |
| 7229 | If the metafied character <I>x</I> is lowercase, run the command |
| 7230 | that is bound to the corresponding uppercase character. |
| 7231 | <DT><B>prefix-meta (ESC)</B> |
| 7232 | |
| 7233 | <DD> |
| 7234 | Metafy the next character typed. |
| 7235 | <FONT SIZE=-1><B>ESC</B> |
| 7236 | |
| 7237 | </FONT> |
| 7238 | <B>f</B> |
| 7239 | |
| 7240 | is equivalent to |
| 7241 | <B>Meta-f</B>. |
| 7242 | |
| 7243 | <DT><B>undo (C-_, C-x C-u)</B> |
| 7244 | |
| 7245 | <DD> |
| 7246 | Incremental undo, separately remembered for each line. |
| 7247 | <DT><B>revert-line (M-r)</B> |
| 7248 | |
| 7249 | <DD> |
| 7250 | Undo all changes made to this line. This is like executing the |
| 7251 | <B>undo</B> |
| 7252 | |
| 7253 | command enough times to return the line to its initial state. |
| 7254 | <DT><B>tilde-expand (M-&)</B> |
| 7255 | |
| 7256 | <DD> |
| 7257 | Perform tilde expansion on the current word. |
| 7258 | <DT><B>set-mark (C-@, M-<space>)</B> |
| 7259 | |
| 7260 | <DD> |
| 7261 | Set the mark to the point. If a |
| 7262 | numeric argument is supplied, the mark is set to that position. |
| 7263 | <DT><B>exchange-point-and-mark (C-x C-x)</B> |
| 7264 | |
| 7265 | <DD> |
| 7266 | Swap the point with the mark. The current cursor position is set to |
| 7267 | the saved position, and the old cursor position is saved as the mark. |
| 7268 | <DT><B>character-search (C-])</B> |
| 7269 | |
| 7270 | <DD> |
| 7271 | A character is read and point is moved to the next occurrence of that |
| 7272 | character. A negative count searches for previous occurrences. |
| 7273 | <DT><B>character-search-backward (M-C-])</B> |
| 7274 | |
| 7275 | <DD> |
| 7276 | A character is read and point is moved to the previous occurrence of that |
| 7277 | character. A negative count searches for subsequent occurrences. |
| 7278 | <DT><B>insert-comment (M-#)</B> |
| 7279 | |
| 7280 | <DD> |
| 7281 | Without a numeric argument, the value of the readline |
| 7282 | <B>comment-begin</B> |
| 7283 | |
| 7284 | variable is inserted at the beginning of the current line. |
| 7285 | If a numeric argument is supplied, this command acts as a toggle: if |
| 7286 | the characters at the beginning of the line do not match the value |
| 7287 | of <B>comment-begin</B>, the value is inserted, otherwise |
| 7288 | the characters in <B>comment-begin</B> are deleted from the beginning of |
| 7289 | the line. |
| 7290 | In either case, the line is accepted as if a newline had been typed. |
| 7291 | The default value of |
| 7292 | <B>comment-begin</B> causes this command to make the current line |
| 7293 | a shell comment. |
| 7294 | If a numeric argument causes the comment character to be removed, the line |
| 7295 | will be executed by the shell. |
| 7296 | <DT><B>glob-complete-word (M-g)</B> |
| 7297 | |
| 7298 | <DD> |
| 7299 | The word before point is treated as a pattern for pathname expansion, |
| 7300 | with an asterisk implicitly appended. This pattern is used to |
| 7301 | generate a list of matching file names for possible completions. |
| 7302 | <DT><B>glob-expand-word (C-x *)</B> |
| 7303 | |
| 7304 | <DD> |
| 7305 | The word before point is treated as a pattern for pathname expansion, |
| 7306 | and the list of matching file names is inserted, replacing the word. |
| 7307 | If a numeric argument is supplied, an asterisk is appended before |
| 7308 | pathname expansion. |
| 7309 | <DT><B>glob-list-expansions (C-x g)</B> |
| 7310 | |
| 7311 | <DD> |
| 7312 | The list of expansions that would have been generated by |
| 7313 | <B>glob-expand-word</B> |
| 7314 | |
| 7315 | is displayed, and the line is redrawn. |
| 7316 | If a numeric argument is supplied, an asterisk is appended before |
| 7317 | pathname expansion. |
| 7318 | <DT><B>dump-functions</B> |
| 7319 | |
| 7320 | <DD> |
| 7321 | Print all of the functions and their key bindings to the |
| 7322 | readline output stream. If a numeric argument is supplied, |
| 7323 | the output is formatted in such a way that it can be made part |
| 7324 | of an <I>inputrc</I> file. |
| 7325 | <DT><B>dump-variables</B> |
| 7326 | |
| 7327 | <DD> |
| 7328 | Print all of the settable readline variables and their values to the |
| 7329 | readline output stream. If a numeric argument is supplied, |
| 7330 | the output is formatted in such a way that it can be made part |
| 7331 | of an <I>inputrc</I> file. |
| 7332 | <DT><B>dump-macros</B> |
| 7333 | |
| 7334 | <DD> |
| 7335 | Print all of the readline key sequences bound to macros and the |
| 7336 | strings they output. If a numeric argument is supplied, |
| 7337 | the output is formatted in such a way that it can be made part |
| 7338 | of an <I>inputrc</I> file. |
| 7339 | <DT><B>display-shell-version (C-x C-v)</B> |
| 7340 | |
| 7341 | <DD> |
| 7342 | Display version information about the current instance of |
| 7343 | <B>bash</B>. |
| 7344 | |
| 7345 | |
| 7346 | </DL> |
| 7347 | <A NAME="lbCV"> </A> |
| 7348 | <H4>Programmable Completion</H4> |
| 7349 | |
| 7350 | <P> |
| 7351 | |
| 7352 | When word completion is attempted for an argument to a command for |
| 7353 | which a completion specification (a <I>compspec</I>) has been defined |
| 7354 | using the <B>complete</B> builtin (see |
| 7355 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 7356 | |
| 7357 | </FONT> |
| 7358 | below), the programmable completion facilities are invoked. |
| 7359 | <P> |
| 7360 | |
| 7361 | First, the command name is identified. |
| 7362 | If a compspec has been defined for that command, the |
| 7363 | compspec is used to generate the list of possible completions for the word. |
| 7364 | If the command word is a full pathname, a compspec for the full |
| 7365 | pathname is searched for first. |
| 7366 | If no compspec is found for the full pathname, an attempt is made to |
| 7367 | find a compspec for the portion following the final slash. |
| 7368 | <P> |
| 7369 | |
| 7370 | Once a compspec has been found, it is used to generate the list of |
| 7371 | matching words. |
| 7372 | If a compspec is not found, the default <B>bash</B> completion as |
| 7373 | described above under <B>Completing</B> is performed. |
| 7374 | <P> |
| 7375 | |
| 7376 | First, the actions specified by the compspec are used. |
| 7377 | Only matches which are prefixed by the word being completed are |
| 7378 | returned. |
| 7379 | When the |
| 7380 | <B>-f</B> |
| 7381 | |
| 7382 | or |
| 7383 | <B>-d</B> |
| 7384 | |
| 7385 | option is used for filename or directory name completion, the shell |
| 7386 | variable |
| 7387 | <FONT SIZE=-1><B>FIGNORE</B> |
| 7388 | |
| 7389 | </FONT> |
| 7390 | is used to filter the matches. |
| 7391 | <P> |
| 7392 | |
| 7393 | Any completions specified by a filename expansion pattern to the |
| 7394 | <B>-G</B> option are generated next. |
| 7395 | The words generated by the pattern need not match the word |
| 7396 | being completed. |
| 7397 | The |
| 7398 | <FONT SIZE=-1><B>GLOBIGNORE</B> |
| 7399 | |
| 7400 | </FONT> |
| 7401 | shell variable is not used to filter the matches, but the |
| 7402 | <FONT SIZE=-1><B>FIGNORE</B> |
| 7403 | |
| 7404 | </FONT> |
| 7405 | variable is used. |
| 7406 | <P> |
| 7407 | |
| 7408 | Next, the string specified as the argument to the <B>-W</B> option |
| 7409 | is considered. |
| 7410 | The string is first split using the characters in the |
| 7411 | <FONT SIZE=-1><B>IFS</B> |
| 7412 | |
| 7413 | </FONT> |
| 7414 | special variable as delimiters. |
| 7415 | Shell quoting is honored. |
| 7416 | Each word is then expanded using |
| 7417 | brace expansion, tilde expansion, parameter and variable expansion, |
| 7418 | command substitution, and arithmetic expansion, |
| 7419 | as described above under |
| 7420 | <FONT SIZE=-1><B>EXPANSION</B>. |
| 7421 | |
| 7422 | </FONT> |
| 7423 | The results are split using the rules described above under |
| 7424 | <B>Word Splitting</B>. |
| 7425 | The results of the expansion are prefix-matched against the word being |
| 7426 | completed, and the matching words become the possible completions. |
| 7427 | <P> |
| 7428 | |
| 7429 | After these matches have been generated, any shell function or command |
| 7430 | specified with the <B>-F</B> and <B>-C</B> options is invoked. |
| 7431 | When the command or function is invoked, the |
| 7432 | <FONT SIZE=-1><B>COMP_LINE</B>, |
| 7433 | |
| 7434 | </FONT> |
| 7435 | <FONT SIZE=-1><B>COMP_POINT</B>, |
| 7436 | |
| 7437 | </FONT> |
| 7438 | <FONT SIZE=-1><B>COMP_KEY</B>, |
| 7439 | |
| 7440 | </FONT> |
| 7441 | and |
| 7442 | <FONT SIZE=-1><B>COMP_TYPE</B> |
| 7443 | |
| 7444 | </FONT> |
| 7445 | variables are assigned values as described above under |
| 7446 | <B>Shell Variables</B>. |
| 7447 | If a shell function is being invoked, the |
| 7448 | <FONT SIZE=-1><B>COMP_WORDS</B> |
| 7449 | |
| 7450 | </FONT> |
| 7451 | and |
| 7452 | <FONT SIZE=-1><B>COMP_CWORD</B> |
| 7453 | |
| 7454 | </FONT> |
| 7455 | variables are also set. |
| 7456 | When the function or command is invoked, the first argument is the |
| 7457 | name of the command whose arguments are being completed, the |
| 7458 | second argument is the word being completed, and the third argument |
| 7459 | is the word preceding the word being completed on the current command line. |
| 7460 | No filtering of the generated completions against the word being completed |
| 7461 | is performed; the function or command has complete freedom in generating |
| 7462 | the matches. |
| 7463 | <P> |
| 7464 | |
| 7465 | Any function specified with <B>-F</B> is invoked first. |
| 7466 | The function may use any of the shell facilities, including the |
| 7467 | <B>compgen</B> builtin described below, to generate the matches. |
| 7468 | It must put the possible completions in the |
| 7469 | <FONT SIZE=-1><B>COMPREPLY</B> |
| 7470 | |
| 7471 | </FONT> |
| 7472 | array variable. |
| 7473 | <P> |
| 7474 | |
| 7475 | Next, any command specified with the <B>-C</B> option is invoked |
| 7476 | in an environment equivalent to command substitution. |
| 7477 | It should print a list of completions, one per line, to the |
| 7478 | standard output. |
| 7479 | Backslash may be used to escape a newline, if necessary. |
| 7480 | <P> |
| 7481 | |
| 7482 | After all of the possible completions are generated, any filter |
| 7483 | specified with the <B>-X</B> option is applied to the list. |
| 7484 | The filter is a pattern as used for pathname expansion; a <B>&</B> |
| 7485 | in the pattern is replaced with the text of the word being completed. |
| 7486 | A literal <B>&</B> may be escaped with a backslash; the backslash |
| 7487 | is removed before attempting a match. |
| 7488 | Any completion that matches the pattern will be removed from the list. |
| 7489 | A leading <B>!</B> negates the pattern; in this case any completion |
| 7490 | not matching the pattern will be removed. |
| 7491 | <P> |
| 7492 | |
| 7493 | Finally, any prefix and suffix specified with the <B>-P</B> and <B>-S</B> |
| 7494 | options are added to each member of the completion list, and the result is |
| 7495 | returned to the readline completion code as the list of possible |
| 7496 | completions. |
| 7497 | <P> |
| 7498 | |
| 7499 | If the previously-applied actions do not generate any matches, and the |
| 7500 | <B>-o dirnames</B> option was supplied to <B>complete</B> when the |
| 7501 | compspec was defined, directory name completion is attempted. |
| 7502 | <P> |
| 7503 | |
| 7504 | If the <B>-o plusdirs</B> option was supplied to <B>complete</B> when the |
| 7505 | compspec was defined, directory name completion is attempted and any |
| 7506 | matches are added to the results of the other actions. |
| 7507 | <P> |
| 7508 | |
| 7509 | By default, if a compspec is found, whatever it generates is returned |
| 7510 | to the completion code as the full set of possible completions. |
| 7511 | The default <B>bash</B> completions are not attempted, and the readline |
| 7512 | default of filename completion is disabled. |
| 7513 | If the <B>-o bashdefault</B> option was supplied to <B>complete</B> when |
| 7514 | the compspec was defined, the <B>bash</B> default completions are attempted |
| 7515 | if the compspec generates no matches. |
| 7516 | If the <B>-o default</B> option was supplied to <B>complete</B> when the |
| 7517 | compspec was defined, readline's default completion will be performed |
| 7518 | if the compspec (and, if attempted, the default <B>bash</B> completions) |
| 7519 | generate no matches. |
| 7520 | <P> |
| 7521 | |
| 7522 | When a compspec indicates that directory name completion is desired, |
| 7523 | the programmable completion functions force readline to append a slash |
| 7524 | to completed names which are symbolic links to directories, subject to |
| 7525 | the value of the <B>mark-directories</B> readline variable, regardless |
| 7526 | of the setting of the <B>mark-symlinked-directories</B> readline variable. |
| 7527 | <A NAME="lbCW"> </A> |
| 7528 | <H3>HISTORY</H3> |
| 7529 | |
| 7530 | When the |
| 7531 | <B>-o history</B> |
| 7532 | |
| 7533 | option to the |
| 7534 | <B>set</B> |
| 7535 | |
| 7536 | builtin is enabled, the shell provides access to the |
| 7537 | <I>command history</I>, |
| 7538 | the list of commands previously typed. |
| 7539 | The value of the <B>HISTSIZE</B> variable is used as the |
| 7540 | number of commands to save in a history list. |
| 7541 | The text of the last |
| 7542 | <FONT SIZE=-1><B>HISTSIZE</B> |
| 7543 | |
| 7544 | </FONT> |
| 7545 | commands (default 500) is saved. The shell |
| 7546 | stores each command in the history list prior to parameter and |
| 7547 | variable expansion (see |
| 7548 | <FONT SIZE=-1><B>EXPANSION</B> |
| 7549 | |
| 7550 | </FONT> |
| 7551 | above) but after history expansion is performed, subject to the |
| 7552 | values of the shell variables |
| 7553 | <FONT SIZE=-1><B>HISTIGNORE</B> |
| 7554 | |
| 7555 | </FONT> |
| 7556 | and |
| 7557 | <FONT SIZE=-1><B>HISTCONTROL</B>. |
| 7558 | |
| 7559 | </FONT> |
| 7560 | <P> |
| 7561 | |
| 7562 | On startup, the history is initialized from the file named by |
| 7563 | the variable |
| 7564 | <FONT SIZE=-1><B>HISTFILE</B> |
| 7565 | |
| 7566 | </FONT> |
| 7567 | (default <A HREF="file:~/.bash_history"><I>~/.bash_history</I></A>). |
| 7568 | The file named by the value of |
| 7569 | <FONT SIZE=-1><B>HISTFILE</B> |
| 7570 | |
| 7571 | </FONT> |
| 7572 | is truncated, if necessary, to contain no more than |
| 7573 | the number of lines specified by the value of |
| 7574 | <FONT SIZE=-1><B>HISTFILESIZE</B>. |
| 7575 | |
| 7576 | </FONT> |
| 7577 | When the history file is read, |
| 7578 | lines beginning with the history comment character followed immediately |
| 7579 | by a digit are interpreted as timestamps for the preceding history line. |
| 7580 | These timestamps are optionally displayed depending on the value of the |
| 7581 | <FONT SIZE=-1><B>HISTTIMEFORMAT</B> |
| 7582 | |
| 7583 | </FONT> |
| 7584 | variable. |
| 7585 | When an interactive shell exits, the last |
| 7586 | <FONT SIZE=-1><B>$HISTSIZE</B> |
| 7587 | |
| 7588 | </FONT> |
| 7589 | lines are copied from the history list to |
| 7590 | <FONT SIZE=-1><B>$HISTFILE</B>. |
| 7591 | |
| 7592 | </FONT> |
| 7593 | If the |
| 7594 | <B>histappend</B> |
| 7595 | |
| 7596 | shell option is enabled |
| 7597 | (see the description of |
| 7598 | <B>shopt</B> |
| 7599 | |
| 7600 | under |
| 7601 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 7602 | |
| 7603 | </FONT> |
| 7604 | below), the lines are appended to the history file, |
| 7605 | otherwise the history file is overwritten. |
| 7606 | If |
| 7607 | <FONT SIZE=-1><B>HISTFILE</B> |
| 7608 | |
| 7609 | </FONT> |
| 7610 | is unset, or if the history file is unwritable, the history is |
| 7611 | not saved. |
| 7612 | If the |
| 7613 | <FONT SIZE=-1> |
| 7614 | </FONT> |
| 7615 | variable is set, time stamps are written to the history file, marked |
| 7616 | with the history comment character, so |
| 7617 | they may be preserved across shell sessions. |
| 7618 | This uses the history comment character to distinguish timestamps from |
| 7619 | other history lines. |
| 7620 | After saving the history, the history file is truncated |
| 7621 | to contain no more than |
| 7622 | <FONT SIZE=-1><B>HISTFILESIZE</B> |
| 7623 | |
| 7624 | </FONT> |
| 7625 | lines. If |
| 7626 | <FONT SIZE=-1><B>HISTFILESIZE</B> |
| 7627 | |
| 7628 | </FONT> |
| 7629 | is not set, no truncation is performed. |
| 7630 | <P> |
| 7631 | |
| 7632 | The builtin command |
| 7633 | <B>fc</B> |
| 7634 | |
| 7635 | (see |
| 7636 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 7637 | |
| 7638 | </FONT> |
| 7639 | below) may be used to list or edit and re-execute a portion of |
| 7640 | the history list. |
| 7641 | The |
| 7642 | <B>history</B> |
| 7643 | |
| 7644 | builtin may be used to display or modify the history list and |
| 7645 | manipulate the history file. |
| 7646 | When using command-line editing, search commands |
| 7647 | are available in each editing mode that provide access to the |
| 7648 | history list. |
| 7649 | <P> |
| 7650 | |
| 7651 | The shell allows control over which commands are saved on the history |
| 7652 | list. The |
| 7653 | <FONT SIZE=-1><B>HISTCONTROL</B> |
| 7654 | |
| 7655 | </FONT> |
| 7656 | and |
| 7657 | <FONT SIZE=-1><B>HISTIGNORE</B> |
| 7658 | |
| 7659 | </FONT> |
| 7660 | variables may be set to cause the shell to save only a subset of the |
| 7661 | commands entered. |
| 7662 | The |
| 7663 | <B>cmdhist</B> |
| 7664 | |
| 7665 | shell option, if enabled, causes the shell to attempt to save each |
| 7666 | line of a multi-line command in the same history entry, adding |
| 7667 | semicolons where necessary to preserve syntactic correctness. |
| 7668 | The |
| 7669 | <B>lithist</B> |
| 7670 | |
| 7671 | shell option causes the shell to save the command with embedded newlines |
| 7672 | instead of semicolons. See the description of the |
| 7673 | <B>shopt</B> |
| 7674 | |
| 7675 | builtin below under |
| 7676 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 7677 | |
| 7678 | </FONT> |
| 7679 | for information on setting and unsetting shell options. |
| 7680 | <A NAME="lbCX"> </A> |
| 7681 | <H3>HISTORY EXPANSION</H3> |
| 7682 | |
| 7683 | <P> |
| 7684 | |
| 7685 | The shell supports a history expansion feature that |
| 7686 | is similar to the history expansion in |
| 7687 | <B>csh.</B> |
| 7688 | |
| 7689 | This section describes what syntax features are available. This |
| 7690 | feature is enabled by default for interactive shells, and can be |
| 7691 | disabled using the |
| 7692 | <B>+H</B> |
| 7693 | |
| 7694 | option to the |
| 7695 | <B>set</B> |
| 7696 | |
| 7697 | builtin command (see |
| 7698 | <FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B> |
| 7699 | |
| 7700 | </FONT> |
| 7701 | below). Non-interactive shells do not perform history expansion |
| 7702 | by default. |
| 7703 | <P> |
| 7704 | |
| 7705 | History expansions introduce words from the history list into |
| 7706 | the input stream, making it easy to repeat commands, insert the |
| 7707 | arguments to a previous command into the current input line, or |
| 7708 | fix errors in previous commands quickly. |
| 7709 | <P> |
| 7710 | |
| 7711 | History expansion is performed immediately after a complete line |
| 7712 | is read, before the shell breaks it into words. |
| 7713 | It takes place in two parts. |
| 7714 | The first is to determine which line from the history list |
| 7715 | to use during substitution. |
| 7716 | The second is to select portions of that line for inclusion into |
| 7717 | the current one. |
| 7718 | The line selected from the history is the <I>event</I>, |
| 7719 | and the portions of that line that are acted upon are <I>words</I>. |
| 7720 | Various <I>modifiers</I> are available to manipulate the selected words. |
| 7721 | The line is broken into words in the same fashion as when reading input, |
| 7722 | so that several <I>metacharacter</I>-separated words surrounded by |
| 7723 | quotes are considered one word. |
| 7724 | History expansions are introduced by the appearance of the |
| 7725 | history expansion character, which is <B>!</B> by default. |
| 7726 | Only backslash (<B>\</B>) and single quotes can quote |
| 7727 | the history expansion character. |
| 7728 | <P> |
| 7729 | |
| 7730 | Several characters inhibit history expansion if found immediately |
| 7731 | following the history expansion character, even if it is unquoted: |
| 7732 | space, tab, newline, carriage return, and <B>=</B>. |
| 7733 | If the <B>extglob</B> shell option is enabled, <B>(</B> will also |
| 7734 | inhibit expansion. |
| 7735 | <P> |
| 7736 | |
| 7737 | Several shell options settable with the |
| 7738 | <B>shopt</B> |
| 7739 | |
| 7740 | builtin may be used to tailor the behavior of history expansion. |
| 7741 | If the |
| 7742 | <B>histverify</B> |
| 7743 | |
| 7744 | shell option is enabled (see the description of the |
| 7745 | <B>shopt</B> |
| 7746 | |
| 7747 | builtin), and |
| 7748 | <B>readline</B> |
| 7749 | |
| 7750 | is being used, history substitutions are not immediately passed to |
| 7751 | the shell parser. |
| 7752 | Instead, the expanded line is reloaded into the |
| 7753 | <B>readline</B> |
| 7754 | |
| 7755 | editing buffer for further modification. |
| 7756 | If |
| 7757 | <B>readline</B> |
| 7758 | |
| 7759 | is being used, and the |
| 7760 | <B>histreedit</B> |
| 7761 | |
| 7762 | shell option is enabled, a failed history substitution will be reloaded |
| 7763 | into the |
| 7764 | <B>readline</B> |
| 7765 | |
| 7766 | editing buffer for correction. |
| 7767 | The |
| 7768 | <B>-p</B> |
| 7769 | |
| 7770 | option to the |
| 7771 | <B>history</B> |
| 7772 | |
| 7773 | builtin command may be used to see what a history expansion will |
| 7774 | do before using it. |
| 7775 | The |
| 7776 | <B>-s</B> |
| 7777 | |
| 7778 | option to the |
| 7779 | <B>history</B> |
| 7780 | |
| 7781 | builtin may be used to add commands to the end of the history list |
| 7782 | without actually executing them, so that they are available for |
| 7783 | subsequent recall. |
| 7784 | <P> |
| 7785 | |
| 7786 | The shell allows control of the various characters used by the |
| 7787 | history expansion mechanism (see the description of |
| 7788 | <B>histchars</B> |
| 7789 | |
| 7790 | above under |
| 7791 | <B>Shell Variables</B>). |
| 7792 | |
| 7793 | The shell uses |
| 7794 | the history comment character to mark history timestamps when |
| 7795 | writing the history file. |
| 7796 | <A NAME="lbCY"> </A> |
| 7797 | <H4>Event Designators</H4> |
| 7798 | |
| 7799 | <P> |
| 7800 | |
| 7801 | An event designator is a reference to a command line entry in the |
| 7802 | history list. |
| 7803 | <P> |
| 7804 | |
| 7805 | |
| 7806 | <DL COMPACT> |
| 7807 | <DT><B>!</B> |
| 7808 | |
| 7809 | <DD> |
| 7810 | Start a history substitution, except when followed by a |
| 7811 | <B>blank</B>, |
| 7812 | |
| 7813 | newline, carriage return, = |
| 7814 | or ( (when the <B>extglob</B> shell option is enabled using |
| 7815 | the <B>shopt</B> builtin). |
| 7816 | <DT><B>!</B><I>n</I> |
| 7817 | |
| 7818 | <DD> |
| 7819 | Refer to command line |
| 7820 | <I>n</I>. |
| 7821 | |
| 7822 | <DT><B>!-</B><I>n</I> |
| 7823 | |
| 7824 | <DD> |
| 7825 | Refer to the current command line minus |
| 7826 | <I>n</I>. |
| 7827 | |
| 7828 | <DT><B>!!</B> |
| 7829 | |
| 7830 | <DD> |
| 7831 | Refer to the previous command. This is a synonym for `!-1'. |
| 7832 | <DT><B>!</B><I>string</I> |
| 7833 | |
| 7834 | <DD> |
| 7835 | Refer to the most recent command starting with |
| 7836 | <I>string</I>. |
| 7837 | |
| 7838 | <DT><B>!?</B><I>string</I><B>[?]</B> |
| 7839 | |
| 7840 | <DD> |
| 7841 | Refer to the most recent command containing |
| 7842 | <I>string</I>. |
| 7843 | |
| 7844 | The trailing <B>?</B> may be omitted if |
| 7845 | <I>string</I> |
| 7846 | |
| 7847 | is followed immediately by a newline. |
| 7848 | <DT><B></B><FONT SIZE=+2><B>^</B></FONT><B></B><I>string1</I><FONT SIZE=+2>^</FONT><I>string2</I><FONT SIZE=+2>^</FONT> |
| 7849 | |
| 7850 | <DD> |
| 7851 | Quick substitution. Repeat the last command, replacing |
| 7852 | <I>string1</I> |
| 7853 | |
| 7854 | with |
| 7855 | <I>string2</I>. |
| 7856 | |
| 7857 | Equivalent to |
| 7858 | ``!!:s/<I>string1</I>/<I>string2</I>/'' |
| 7859 | (see <B>Modifiers</B> below). |
| 7860 | <DT><B>!#</B> |
| 7861 | |
| 7862 | <DD> |
| 7863 | The entire command line typed so far. |
| 7864 | |
| 7865 | </DL> |
| 7866 | <A NAME="lbCZ"> </A> |
| 7867 | <H4>Word Designators</H4> |
| 7868 | |
| 7869 | <P> |
| 7870 | |
| 7871 | Word designators are used to select desired words from the event. |
| 7872 | A |
| 7873 | <B>:</B> |
| 7874 | |
| 7875 | separates the event specification from the word designator. |
| 7876 | It may be omitted if the word designator begins with a |
| 7877 | <B>^</B>, |
| 7878 | |
| 7879 | <B>$</B>, |
| 7880 | |
| 7881 | <B>*</B>, |
| 7882 | |
| 7883 | <B>-</B>, |
| 7884 | |
| 7885 | or |
| 7886 | <B>%</B>. |
| 7887 | |
| 7888 | Words are numbered from the beginning of the line, |
| 7889 | with the first word being denoted by 0 (zero). |
| 7890 | Words are inserted into the current line separated by single spaces. |
| 7891 | <P> |
| 7892 | |
| 7893 | |
| 7894 | <DL COMPACT> |
| 7895 | <DT><B>0 (zero)</B> |
| 7896 | |
| 7897 | <DD> |
| 7898 | The zeroth word. For the shell, this is the command |
| 7899 | word. |
| 7900 | <DT><I>n</I> |
| 7901 | |
| 7902 | <DD> |
| 7903 | The <I>n</I>th word. |
| 7904 | <DT><B>^</B> |
| 7905 | |
| 7906 | <DD> |
| 7907 | The first argument. That is, word 1. |
| 7908 | <DT><B>$</B> |
| 7909 | |
| 7910 | <DD> |
| 7911 | The last argument. |
| 7912 | <DT><B>%</B> |
| 7913 | |
| 7914 | <DD> |
| 7915 | The word matched by the most recent `?<I>string</I>?' search. |
| 7916 | <DT><I>x</I><B>-</B>y |
| 7917 | |
| 7918 | <DD> |
| 7919 | A range of words; `-<I>y</I>' abbreviates `0-<I>y</I>'. |
| 7920 | <DT><B>*</B> |
| 7921 | |
| 7922 | <DD> |
| 7923 | All of the words but the zeroth. This is a synonym |
| 7924 | for `<I>1-$</I>'. It is not an error to use |
| 7925 | <B>*</B> |
| 7926 | |
| 7927 | if there is just one |
| 7928 | word in the event; the empty string is returned in that case. |
| 7929 | <DT><B>x*</B> |
| 7930 | |
| 7931 | <DD> |
| 7932 | Abbreviates <I>x-$</I>. |
| 7933 | <DT><B>x-</B> |
| 7934 | |
| 7935 | <DD> |
| 7936 | Abbreviates <I>x-$</I> like <B>x*</B>, but omits the last word. |
| 7937 | |
| 7938 | </DL> |
| 7939 | <P> |
| 7940 | |
| 7941 | If a word designator is supplied without an event specification, the |
| 7942 | previous command is used as the event. |
| 7943 | <A NAME="lbDA"> </A> |
| 7944 | <H4>Modifiers</H4> |
| 7945 | |
| 7946 | <P> |
| 7947 | |
| 7948 | After the optional word designator, there may appear a sequence of |
| 7949 | one or more of the following modifiers, each preceded by a `:'. |
| 7950 | <P> |
| 7951 | |
| 7952 | |
| 7953 | <P> |
| 7954 | |
| 7955 | <DL COMPACT> |
| 7956 | <DT><B>h</B> |
| 7957 | |
| 7958 | <DD> |
| 7959 | Remove a trailing file name component, leaving only the head. |
| 7960 | <DT><B>t</B> |
| 7961 | |
| 7962 | <DD> |
| 7963 | Remove all leading file name components, leaving the tail. |
| 7964 | <DT><B>r</B> |
| 7965 | |
| 7966 | <DD> |
| 7967 | Remove a trailing suffix of the form <I>.xxx</I>, leaving the |
| 7968 | basename. |
| 7969 | <DT><B>e</B> |
| 7970 | |
| 7971 | <DD> |
| 7972 | Remove all but the trailing suffix. |
| 7973 | <DT><B>p</B> |
| 7974 | |
| 7975 | <DD> |
| 7976 | Print the new command but do not execute it. |
| 7977 | <DT><B>q</B> |
| 7978 | |
| 7979 | <DD> |
| 7980 | Quote the substituted words, escaping further substitutions. |
| 7981 | <DT><B>x</B> |
| 7982 | |
| 7983 | <DD> |
| 7984 | Quote the substituted words as with |
| 7985 | <B>q</B>, |
| 7986 | |
| 7987 | but break into words at |
| 7988 | <B>blanks</B> |
| 7989 | |
| 7990 | and newlines. |
| 7991 | <DT><B>s/</B><I>old</I>/<I>new</I>/ |
| 7992 | |
| 7993 | <DD> |
| 7994 | Substitute |
| 7995 | <I>new</I> |
| 7996 | |
| 7997 | for the first occurrence of |
| 7998 | <I>old</I> |
| 7999 | |
| 8000 | in the event line. Any delimiter can be used in place of /. The |
| 8001 | final delimiter is optional if it is the last character of the |
| 8002 | event line. The delimiter may be quoted in |
| 8003 | <I>old</I> |
| 8004 | |
| 8005 | and |
| 8006 | <I>new</I> |
| 8007 | |
| 8008 | with a single backslash. If & appears in |
| 8009 | <I>new</I>, |
| 8010 | |
| 8011 | it is replaced by |
| 8012 | <I>old</I>. |
| 8013 | |
| 8014 | A single backslash will quote the &. If |
| 8015 | <I>old</I> |
| 8016 | |
| 8017 | is null, it is set to the last |
| 8018 | <I>old</I> |
| 8019 | |
| 8020 | substituted, or, if no previous history substitutions took place, |
| 8021 | the last |
| 8022 | <I>string</I> |
| 8023 | |
| 8024 | in a |
| 8025 | <B>!?</B><I>string</I><B>[?]</B> |
| 8026 | |
| 8027 | search. |
| 8028 | <DT><B>&</B> |
| 8029 | |
| 8030 | <DD> |
| 8031 | Repeat the previous substitution. |
| 8032 | <DT><B>g</B> |
| 8033 | |
| 8034 | <DD> |
| 8035 | Cause changes to be applied over the entire event line. This is |
| 8036 | used in conjunction with `<B>:s</B>' (e.g., `<B>:gs/</B><I>old</I>/<I>new</I>/') |
| 8037 | or `<B>:&</B>'. If used with |
| 8038 | `<B>:s</B>', any delimiter can be used |
| 8039 | in place of /, and the final delimiter is optional |
| 8040 | if it is the last character of the event line. |
| 8041 | An <B>a</B> may be used as a synonym for <B>g</B>. |
| 8042 | <DT><B>G</B> |
| 8043 | |
| 8044 | <DD> |
| 8045 | Apply the following `<B>s</B>' modifier once to each word in the event line. |
| 8046 | |
| 8047 | </DL> |
| 8048 | <A NAME="lbDB"> </A> |
| 8049 | <H3>SHELL BUILTIN COMMANDS</H3> |
| 8050 | |
| 8051 | |
| 8052 | |
| 8053 | <P> |
| 8054 | |
| 8055 | Unless otherwise noted, each builtin command documented in this |
| 8056 | section as accepting options preceded by |
| 8057 | <B>-</B> |
| 8058 | |
| 8059 | accepts |
| 8060 | <B>--</B> |
| 8061 | |
| 8062 | to signify the end of the options. |
| 8063 | For example, the <B>:</B>, <B>true</B>, <B>false</B>, and <B>test</B> builtins |
| 8064 | do not accept options. |
| 8065 | <P> |
| 8066 | |
| 8067 | <DL COMPACT> |
| 8068 | <DT><B>:</B> [<I>arguments</I>]<DD> |
| 8069 | |
| 8070 | No effect; the command does nothing beyond expanding |
| 8071 | <I>arguments</I> |
| 8072 | |
| 8073 | and performing any specified |
| 8074 | redirections. A zero exit code is returned. |
| 8075 | <DT><B> . </B> <I>filename</I> [<I>arguments</I>]<DD> |
| 8076 | |
| 8077 | <DT><B>source</B> <I>filename</I> [<I>arguments</I>]<DD> |
| 8078 | |
| 8079 | Read and execute commands from |
| 8080 | <I>filename</I> |
| 8081 | |
| 8082 | in the current |
| 8083 | shell environment and return the exit status of the last command |
| 8084 | executed from |
| 8085 | <I>filename</I>. |
| 8086 | |
| 8087 | If |
| 8088 | <I>filename</I> |
| 8089 | |
| 8090 | does not contain a slash, file names in |
| 8091 | <FONT SIZE=-1><B>PATH</B> |
| 8092 | |
| 8093 | </FONT> |
| 8094 | are used to find the directory containing |
| 8095 | <I>filename</I>. |
| 8096 | |
| 8097 | The file searched for in |
| 8098 | <FONT SIZE=-1><B>PATH</B> |
| 8099 | |
| 8100 | </FONT> |
| 8101 | need not be executable. |
| 8102 | When <B>bash</B> is not in <I>posix mode</I>, the current directory is |
| 8103 | searched if no file is found in |
| 8104 | <FONT SIZE=-1><B>PATH</B>. |
| 8105 | |
| 8106 | </FONT> |
| 8107 | If the |
| 8108 | <B>sourcepath</B> |
| 8109 | |
| 8110 | option to the |
| 8111 | <B>shopt</B> |
| 8112 | |
| 8113 | builtin command is turned off, the |
| 8114 | <FONT SIZE=-1><B>PATH</B> |
| 8115 | |
| 8116 | </FONT> |
| 8117 | is not searched. |
| 8118 | If any <I>arguments</I> are supplied, they become the positional |
| 8119 | parameters when <I>filename</I> is executed. Otherwise the positional |
| 8120 | parameters are unchanged. |
| 8121 | The return status is the status of the last command exited within |
| 8122 | the script (0 if no commands are executed), and false if |
| 8123 | <I>filename</I> |
| 8124 | |
| 8125 | is not found or cannot be read. |
| 8126 | <DT><B>alias</B> [<B>-p</B>] [<I>name</I>[=<I>value</I>] ...]<DD> |
| 8127 | <B>Alias</B> with no arguments or with the |
| 8128 | <B>-p</B> |
| 8129 | |
| 8130 | option prints the list of aliases in the form |
| 8131 | <B>alias</B> <I>name</I>=<I>value</I> on standard output. |
| 8132 | When arguments are supplied, an alias is defined for |
| 8133 | each <I>name</I> whose <I>value</I> is given. |
| 8134 | A trailing space in <I>value</I> causes the next word to be |
| 8135 | checked for alias substitution when the alias is expanded. |
| 8136 | For each <I>name</I> in the argument list for which no <I>value</I> |
| 8137 | is supplied, the name and value of the alias is printed. |
| 8138 | <B>Alias</B> returns true unless a <I>name</I> is given for which |
| 8139 | no alias has been defined. |
| 8140 | <DT><B>bg</B> [<I>jobspec</I> ...]<DD> |
| 8141 | Resume each suspended job <I>jobspec</I> in the background, as if it |
| 8142 | had been started with |
| 8143 | <B>&</B>. |
| 8144 | |
| 8145 | If |
| 8146 | <I>jobspec</I> |
| 8147 | |
| 8148 | is not present, the shell's notion of the <I>current job</I> is used. |
| 8149 | <B>bg</B> |
| 8150 | |
| 8151 | <I>jobspec</I> |
| 8152 | |
| 8153 | returns 0 unless run when job control is disabled or, when run with |
| 8154 | job control enabled, any specified <I>jobspec</I> was not found |
| 8155 | or was started without job control. |
| 8156 | <DT><B>bind</B> [<B>-m</B> <I>keymap</I>] [<B>-lpsvPSV</B>]<DD> |
| 8157 | |
| 8158 | <DT><B>bind</B> [<B>-m</B> <I>keymap</I>] [<B>-q</B> <I>function</I>] [<B>-u</B> <I>function</I>] [<B>-r</B> <I>keyseq</I>]<DD> |
| 8159 | <DT><B>bind</B> [<B>-m</B> <I>keymap</I>] <B>-f</B> <I>filename</I><DD> |
| 8160 | <DT><B>bind</B> [<B>-m</B> <I>keymap</I>] <B>-x</B> <I>keyseq</I>:<I>shell-command</I><DD> |
| 8161 | <DT><B>bind</B> [<B>-m</B> <I>keymap</I>] <I>keyseq</I>:<I>function-name</I><DD> |
| 8162 | <DT><B>bind</B> <I>readline-command</I><DD> |
| 8163 | |
| 8164 | Display current |
| 8165 | <B>readline</B> |
| 8166 | |
| 8167 | key and function bindings, bind a key sequence to a |
| 8168 | <B>readline</B> |
| 8169 | |
| 8170 | function or macro, or set a |
| 8171 | <B>readline</B> |
| 8172 | |
| 8173 | variable. |
| 8174 | Each non-option argument is a command as it would appear in |
| 8175 | <I>.inputrc</I>, |
| 8176 | |
| 8177 | but each binding or command must be passed as a separate argument; |
| 8178 | e.g., '"\C-x\C-r": re-read-init-file'. |
| 8179 | Options, if supplied, have the following meanings: |
| 8180 | <DL COMPACT><DT><DD> |
| 8181 | |
| 8182 | <DL COMPACT> |
| 8183 | <DT><B>-m </B><I>keymap</I> |
| 8184 | |
| 8185 | <DD> |
| 8186 | Use |
| 8187 | <I>keymap</I> |
| 8188 | |
| 8189 | as the keymap to be affected by the subsequent bindings. |
| 8190 | Acceptable |
| 8191 | <I>keymap</I> |
| 8192 | |
| 8193 | names are |
| 8194 | <I>emacs, emacs-standard, emacs-meta, emacs-ctlx, vi, |
| 8195 | vi-move, vi-command</I>, and |
| 8196 | <I>vi-insert</I>. |
| 8197 | |
| 8198 | <I>vi</I> is equivalent to <I>vi-command</I>; <I>emacs</I> is |
| 8199 | equivalent to <I>emacs-standard</I>. |
| 8200 | <DT><B>-l</B> |
| 8201 | |
| 8202 | <DD> |
| 8203 | List the names of all <B>readline</B> functions. |
| 8204 | <DT><B>-p</B> |
| 8205 | |
| 8206 | <DD> |
| 8207 | Display <B>readline</B> function names and bindings in such a way |
| 8208 | that they can be re-read. |
| 8209 | <DT><B>-P</B> |
| 8210 | |
| 8211 | <DD> |
| 8212 | List current <B>readline</B> function names and bindings. |
| 8213 | <DT><B>-s</B> |
| 8214 | |
| 8215 | <DD> |
| 8216 | Display <B>readline</B> key sequences bound to macros and the strings |
| 8217 | they output in such a way that they can be re-read. |
| 8218 | <DT><B>-S</B> |
| 8219 | |
| 8220 | <DD> |
| 8221 | Display <B>readline</B> key sequences bound to macros and the strings |
| 8222 | they output. |
| 8223 | <DT><B>-v</B> |
| 8224 | |
| 8225 | <DD> |
| 8226 | Display <B>readline</B> variable names and values in such a way that they |
| 8227 | can be re-read. |
| 8228 | <DT><B>-V</B> |
| 8229 | |
| 8230 | <DD> |
| 8231 | List current <B>readline</B> variable names and values. |
| 8232 | <DT><B>-f </B><I>filename</I> |
| 8233 | |
| 8234 | <DD> |
| 8235 | Read key bindings from <I>filename</I>. |
| 8236 | <DT><B>-q </B><I>function</I> |
| 8237 | |
| 8238 | <DD> |
| 8239 | Query about which keys invoke the named <I>function</I>. |
| 8240 | <DT><B>-u </B><I>function</I> |
| 8241 | |
| 8242 | <DD> |
| 8243 | Unbind all keys bound to the named <I>function</I>. |
| 8244 | <DT><B>-r </B><I>keyseq</I> |
| 8245 | |
| 8246 | <DD> |
| 8247 | Remove any current binding for <I>keyseq</I>. |
| 8248 | <DT><B>-x </B><I>keyseq</I>:<I>shell-command</I> |
| 8249 | |
| 8250 | <DD> |
| 8251 | Cause <I>shell-command</I> to be executed whenever <I>keyseq</I> is |
| 8252 | entered. |
| 8253 | When <I>shell-command</I> is executed, the shell sets the |
| 8254 | <B>READLINE_LINE</B> |
| 8255 | |
| 8256 | variable to the contents of the <B>readline</B> line buffer and the |
| 8257 | <B>READLINE_POINT</B> |
| 8258 | |
| 8259 | variable to the current location of the insertion point. |
| 8260 | If the executed command changes the value of |
| 8261 | <B>READLINE_LINE</B> |
| 8262 | |
| 8263 | or |
| 8264 | <B>READLINE_POINT</B>, |
| 8265 | |
| 8266 | those new values will be reflected in the editing state. |
| 8267 | |
| 8268 | </DL> |
| 8269 | <P> |
| 8270 | |
| 8271 | The return value is 0 unless an unrecognized option is given or an |
| 8272 | error occurred. |
| 8273 | </DL> |
| 8274 | |
| 8275 | <DT><B>break</B> [<I>n</I>]<DD> |
| 8276 | Exit from within a |
| 8277 | <B>for</B>, |
| 8278 | |
| 8279 | <B>while</B>, |
| 8280 | |
| 8281 | <B>until</B>, |
| 8282 | |
| 8283 | or |
| 8284 | <B>select</B> |
| 8285 | |
| 8286 | loop. If <I>n</I> is specified, break <I>n</I> levels. |
| 8287 | <I>n</I> |
| 8288 | |
| 8289 | must be >= 1. If |
| 8290 | <I>n</I> |
| 8291 | |
| 8292 | is greater than the number of enclosing loops, all enclosing loops |
| 8293 | are exited. |
| 8294 | The return value is 0 unless <I>n</I> is not greater than or equal to 1. |
| 8295 | <DT><B>builtin</B> <I>shell-builtin</I> [<I>arguments</I>]<DD> |
| 8296 | Execute the specified shell builtin, passing it |
| 8297 | <I>arguments</I>, |
| 8298 | |
| 8299 | and return its exit status. |
| 8300 | This is useful when defining a |
| 8301 | function whose name is the same as a shell builtin, |
| 8302 | retaining the functionality of the builtin within the function. |
| 8303 | The <B>cd</B> builtin is commonly redefined this way. |
| 8304 | The return status is false if |
| 8305 | <I>shell-builtin</I> |
| 8306 | |
| 8307 | is not a shell builtin command. |
| 8308 | <DT><B>caller</B> [<I>expr</I>]<DD> |
| 8309 | Returns the context of any active subroutine call (a shell function or |
| 8310 | a script executed with the <B>.</B> or <B>source</B> builtins. |
| 8311 | Without <I>expr</I>, <B>caller</B> displays the line number and source |
| 8312 | filename of the current subroutine call. |
| 8313 | If a non-negative integer is supplied as <I>expr</I>, <B>caller</B> |
| 8314 | displays the line number, subroutine name, and source file corresponding |
| 8315 | to that position in the current execution call stack. This extra |
| 8316 | information may be used, for example, to print a stack trace. The |
| 8317 | current frame is frame 0. |
| 8318 | The return value is 0 unless the shell is not executing a subroutine |
| 8319 | call or <I>expr</I> does not correspond to a valid position in the |
| 8320 | call stack. |
| 8321 | <DT><B>cd</B> [<B>-L|-P</B>] [<I>dir</I>]<DD> |
| 8322 | Change the current directory to <I>dir</I>. The variable |
| 8323 | <FONT SIZE=-1><B>HOME</B> |
| 8324 | |
| 8325 | </FONT> |
| 8326 | is the |
| 8327 | default |
| 8328 | <I>dir</I>. |
| 8329 | |
| 8330 | The variable |
| 8331 | <FONT SIZE=-1><B>CDPATH</B> |
| 8332 | |
| 8333 | </FONT> |
| 8334 | defines the search path for the directory containing |
| 8335 | <I>dir</I>. |
| 8336 | |
| 8337 | Alternative directory names in |
| 8338 | <FONT SIZE=-1><B>CDPATH</B> |
| 8339 | |
| 8340 | </FONT> |
| 8341 | are separated by a colon (:). A null directory name in |
| 8342 | <FONT SIZE=-1><B>CDPATH</B> |
| 8343 | |
| 8344 | </FONT> |
| 8345 | is the same as the current directory, i.e., ``<B>.</B>''. If |
| 8346 | <I>dir</I> |
| 8347 | |
| 8348 | begins with a slash (/), |
| 8349 | then |
| 8350 | <FONT SIZE=-1><B>CDPATH</B> |
| 8351 | |
| 8352 | </FONT> |
| 8353 | is not used. The |
| 8354 | <B>-P</B> |
| 8355 | |
| 8356 | option says to use the physical directory structure instead of |
| 8357 | following symbolic links (see also the |
| 8358 | <B>-P</B> |
| 8359 | |
| 8360 | option to the |
| 8361 | <B>set</B> |
| 8362 | |
| 8363 | builtin command); the |
| 8364 | <B>-L</B> |
| 8365 | |
| 8366 | option forces symbolic links to be followed. An argument of |
| 8367 | <B>-</B> |
| 8368 | |
| 8369 | is equivalent to |
| 8370 | <FONT SIZE=-1><B>$OLDPWD</B>. |
| 8371 | |
| 8372 | </FONT> |
| 8373 | If a non-empty directory name from <B>CDPATH</B> is used, or if |
| 8374 | <B>-</B> is the first argument, and the directory change is |
| 8375 | successful, the absolute pathname of the new working directory is |
| 8376 | written to the standard output. |
| 8377 | The return value is true if the directory was successfully changed; |
| 8378 | false otherwise. |
| 8379 | <DT><B>command</B> [<B>-pVv</B>] <I>command</I> [<I>arg</I> ...]<DD> |
| 8380 | Run |
| 8381 | <I>command</I> |
| 8382 | |
| 8383 | with |
| 8384 | <I>args</I> |
| 8385 | |
| 8386 | suppressing the normal shell function lookup. Only builtin |
| 8387 | commands or commands found in the |
| 8388 | <FONT SIZE=-1><B>PATH</B> |
| 8389 | |
| 8390 | </FONT> |
| 8391 | are executed. If the |
| 8392 | <B>-p</B> |
| 8393 | |
| 8394 | option is given, the search for |
| 8395 | <I>command</I> |
| 8396 | |
| 8397 | is performed using a default value for |
| 8398 | <B>PATH</B> |
| 8399 | |
| 8400 | that is guaranteed to find all of the standard utilities. |
| 8401 | If either the |
| 8402 | <B>-V</B> |
| 8403 | |
| 8404 | or |
| 8405 | <B>-v</B> |
| 8406 | |
| 8407 | option is supplied, a description of |
| 8408 | <I>command</I> |
| 8409 | |
| 8410 | is printed. The |
| 8411 | <B>-v</B> |
| 8412 | |
| 8413 | option causes a single word indicating the command or file name |
| 8414 | used to invoke |
| 8415 | <I>command</I> |
| 8416 | |
| 8417 | to be displayed; the |
| 8418 | <B>-V</B> |
| 8419 | |
| 8420 | option produces a more verbose description. |
| 8421 | If the |
| 8422 | <B>-V</B> |
| 8423 | |
| 8424 | or |
| 8425 | <B>-v</B> |
| 8426 | |
| 8427 | option is supplied, the exit status is 0 if |
| 8428 | <I>command</I> |
| 8429 | |
| 8430 | was found, and 1 if not. If neither option is supplied and |
| 8431 | an error occurred or |
| 8432 | <I>command</I> |
| 8433 | |
| 8434 | cannot be found, the exit status is 127. Otherwise, the exit status of the |
| 8435 | <B>command</B> |
| 8436 | |
| 8437 | builtin is the exit status of |
| 8438 | <I>command</I>. |
| 8439 | |
| 8440 | <DT><B>compgen</B> [<I>option</I>] [<I>word</I>]<DD> |
| 8441 | Generate possible completion matches for <I>word</I> according to |
| 8442 | the <I>option</I>s, which may be any option accepted by the |
| 8443 | <B>complete</B> |
| 8444 | |
| 8445 | builtin with the exception of <B>-p</B> and <B>-r</B>, and write |
| 8446 | the matches to the standard output. |
| 8447 | When using the <B>-F</B> or <B>-C</B> options, the various shell variables |
| 8448 | set by the programmable completion facilities, while available, will not |
| 8449 | have useful values. |
| 8450 | <P> |
| 8451 | The matches will be generated in the same way as if the programmable |
| 8452 | completion code had generated them directly from a completion specification |
| 8453 | with the same flags. |
| 8454 | If <I>word</I> is specified, only those completions matching <I>word</I> |
| 8455 | will be displayed. |
| 8456 | <P> |
| 8457 | The return value is true unless an invalid option is supplied, or no |
| 8458 | matches were generated. |
| 8459 | <DT><B>complete</B> [<B>-abcdefgjksuv</B>] [<B>-o</B> <I>comp-option</I>] [<B>-E</B>] [<B>-A</B> <I>action</I>] [<B>-G</B> <I>globpat</I>] [<B>-W</B> <I>wordlist</I>] [<B>-F</B> <I>function</I>] [<B>-C</B> <I>command</I>]<DD> |
| 8460 | <BR> |
| 8461 | |
| 8462 | [<B>-X</B> <I>filterpat</I>] [<B>-P</B> <I>prefix</I>] [<B>-S</B> <I>suffix</I>] <I>name</I> [<I>name ...</I>] |
| 8463 | |
| 8464 | <DT><B>complete</B> <B>-pr</B> [<B>-E</B>] [<I>name</I> ...]<DD> |
| 8465 | |
| 8466 | Specify how arguments to each <I>name</I> should be completed. |
| 8467 | If the <B>-p</B> option is supplied, or if no options are supplied, |
| 8468 | existing completion specifications are printed in a way that allows |
| 8469 | them to be reused as input. |
| 8470 | The <B>-r</B> option removes a completion specification for |
| 8471 | each <I>name</I>, or, if no <I>name</I>s are supplied, all |
| 8472 | completion specifications. |
| 8473 | The <B>-E</B> option indicates that the remaining options and actions should |
| 8474 | apply to ``empty'' command completion; that is, completion attempted on a |
| 8475 | blank line. |
| 8476 | <P> |
| 8477 | The process of applying these completion specifications when word completion |
| 8478 | is attempted is described above under <B>Programmable Completion</B>. |
| 8479 | <P> |
| 8480 | Other options, if specified, have the following meanings. |
| 8481 | The arguments to the <B>-G</B>, <B>-W</B>, and <B>-X</B> options |
| 8482 | (and, if necessary, the <B>-P</B> and <B>-S</B> options) |
| 8483 | should be quoted to protect them from expansion before the |
| 8484 | <B>complete</B> |
| 8485 | |
| 8486 | builtin is invoked. |
| 8487 | <DL COMPACT><DT><DD> |
| 8488 | |
| 8489 | <DL COMPACT> |
| 8490 | <DT><B>-o</B> <I>comp-option</I><DD> |
| 8491 | The <I>comp-option</I> controls several aspects of the compspec's behavior |
| 8492 | beyond the simple generation of completions. |
| 8493 | <I>comp-option</I> may be one of: |
| 8494 | <DL COMPACT><DT><DD> |
| 8495 | <DL COMPACT> |
| 8496 | <DT><B>bashdefault</B> |
| 8497 | |
| 8498 | <DD> |
| 8499 | Perform the rest of the default <B>bash</B> completions if the compspec |
| 8500 | generates no matches. |
| 8501 | <DT><B>default</B> |
| 8502 | |
| 8503 | <DD> |
| 8504 | Use readline's default filename completion if the compspec generates |
| 8505 | no matches. |
| 8506 | <DT><B>dirnames</B> |
| 8507 | |
| 8508 | <DD> |
| 8509 | Perform directory name completion if the compspec generates no matches. |
| 8510 | <DT><B>filenames</B> |
| 8511 | |
| 8512 | <DD> |
| 8513 | Tell readline that the compspec generates filenames, so it can perform any |
| 8514 | filename-specific processing (like adding a slash to directory names, |
| 8515 | quoting special characters, or suppressing trailing spaces). |
| 8516 | Intended to be used with shell functions. |
| 8517 | <DT><B>nospace</B> |
| 8518 | |
| 8519 | <DD> |
| 8520 | Tell readline not to append a space (the default) to words completed at |
| 8521 | the end of the line. |
| 8522 | <DT><B>plusdirs</B> |
| 8523 | |
| 8524 | <DD> |
| 8525 | After any matches defined by the compspec are generated, |
| 8526 | directory name completion is attempted and any |
| 8527 | matches are added to the results of the other actions. |
| 8528 | </DL></DL> |
| 8529 | |
| 8530 | <DT><B>-A</B> <I>action</I><DD> |
| 8531 | The <I>action</I> may be one of the following to generate a list of possible |
| 8532 | completions: |
| 8533 | <DL COMPACT><DT><DD> |
| 8534 | <DL COMPACT> |
| 8535 | <DT><B>alias</B> |
| 8536 | |
| 8537 | <DD> |
| 8538 | Alias names. May also be specified as <B>-a</B>. |
| 8539 | <DT><B>arrayvar</B> |
| 8540 | |
| 8541 | <DD> |
| 8542 | Array variable names. |
| 8543 | <DT><B>binding</B> |
| 8544 | |
| 8545 | <DD> |
| 8546 | <B>Readline</B> key binding names. |
| 8547 | <DT><B>builtin</B> |
| 8548 | |
| 8549 | <DD> |
| 8550 | Names of shell builtin commands. May also be specified as <B>-b</B>. |
| 8551 | <DT><B>command</B> |
| 8552 | |
| 8553 | <DD> |
| 8554 | Command names. May also be specified as <B>-c</B>. |
| 8555 | <DT><B>directory</B> |
| 8556 | |
| 8557 | <DD> |
| 8558 | Directory names. May also be specified as <B>-d</B>. |
| 8559 | <DT><B>disabled</B> |
| 8560 | |
| 8561 | <DD> |
| 8562 | Names of disabled shell builtins. |
| 8563 | <DT><B>enabled</B> |
| 8564 | |
| 8565 | <DD> |
| 8566 | Names of enabled shell builtins. |
| 8567 | <DT><B>export</B> |
| 8568 | |
| 8569 | <DD> |
| 8570 | Names of exported shell variables. May also be specified as <B>-e</B>. |
| 8571 | <DT><B>file</B> |
| 8572 | |
| 8573 | <DD> |
| 8574 | File names. May also be specified as <B>-f</B>. |
| 8575 | <DT><B>function</B> |
| 8576 | |
| 8577 | <DD> |
| 8578 | Names of shell functions. |
| 8579 | <DT><B>group</B> |
| 8580 | |
| 8581 | <DD> |
| 8582 | Group names. May also be specified as <B>-g</B>. |
| 8583 | <DT><B>helptopic</B> |
| 8584 | |
| 8585 | <DD> |
| 8586 | Help topics as accepted by the <B>help</B> builtin. |
| 8587 | <DT><B>hostname</B> |
| 8588 | |
| 8589 | <DD> |
| 8590 | Hostnames, as taken from the file specified by the |
| 8591 | <FONT SIZE=-1><B>HOSTFILE</B> |
| 8592 | |
| 8593 | </FONT> |
| 8594 | shell variable. |
| 8595 | <DT><B>job</B> |
| 8596 | |
| 8597 | <DD> |
| 8598 | Job names, if job control is active. May also be specified as <B>-j</B>. |
| 8599 | <DT><B>keyword</B> |
| 8600 | |
| 8601 | <DD> |
| 8602 | Shell reserved words. May also be specified as <B>-k</B>. |
| 8603 | <DT><B>running</B> |
| 8604 | |
| 8605 | <DD> |
| 8606 | Names of running jobs, if job control is active. |
| 8607 | <DT><B>service</B> |
| 8608 | |
| 8609 | <DD> |
| 8610 | Service names. May also be specified as <B>-s</B>. |
| 8611 | <DT><B>setopt</B> |
| 8612 | |
| 8613 | <DD> |
| 8614 | Valid arguments for the <B>-o</B> option to the <B>set</B> builtin. |
| 8615 | <DT><B>shopt</B> |
| 8616 | |
| 8617 | <DD> |
| 8618 | Shell option names as accepted by the <B>shopt</B> builtin. |
| 8619 | <DT><B>signal</B> |
| 8620 | |
| 8621 | <DD> |
| 8622 | Signal names. |
| 8623 | <DT><B>stopped</B> |
| 8624 | |
| 8625 | <DD> |
| 8626 | Names of stopped jobs, if job control is active. |
| 8627 | <DT><B>user</B> |
| 8628 | |
| 8629 | <DD> |
| 8630 | User names. May also be specified as <B>-u</B>. |
| 8631 | <DT><B>variable</B> |
| 8632 | |
| 8633 | <DD> |
| 8634 | Names of all shell variables. May also be specified as <B>-v</B>. |
| 8635 | </DL></DL> |
| 8636 | |
| 8637 | <DT><B>-G</B> <I>globpat</I><DD> |
| 8638 | The filename expansion pattern <I>globpat</I> is expanded to generate |
| 8639 | the possible completions. |
| 8640 | <DT><B>-W</B> <I>wordlist</I><DD> |
| 8641 | The <I>wordlist</I> is split using the characters in the |
| 8642 | <FONT SIZE=-1><B>IFS</B> |
| 8643 | |
| 8644 | </FONT> |
| 8645 | special variable as delimiters, and each resultant word is expanded. |
| 8646 | The possible completions are the members of the resultant list which |
| 8647 | match the word being completed. |
| 8648 | <DT><B>-C</B> <I>command</I><DD> |
| 8649 | <I>command</I> is executed in a subshell environment, and its output is |
| 8650 | used as the possible completions. |
| 8651 | <DT><B>-F</B> <I>function</I><DD> |
| 8652 | The shell function <I>function</I> is executed in the current shell |
| 8653 | environment. |
| 8654 | When it finishes, the possible completions are retrieved from the value |
| 8655 | of the |
| 8656 | <FONT SIZE=-1><B>COMPREPLY</B> |
| 8657 | |
| 8658 | </FONT> |
| 8659 | array variable. |
| 8660 | <DT><B>-X</B> <I>filterpat</I><DD> |
| 8661 | <I>filterpat</I> is a pattern as used for filename expansion. |
| 8662 | It is applied to the list of possible completions generated by the |
| 8663 | preceding options and arguments, and each completion matching |
| 8664 | <I>filterpat</I> is removed from the list. |
| 8665 | A leading <B>!</B> in <I>filterpat</I> negates the pattern; in this |
| 8666 | case, any completion not matching <I>filterpat</I> is removed. |
| 8667 | <DT><B>-P</B> <I>prefix</I><DD> |
| 8668 | <I>prefix</I> is added at the beginning of each possible completion |
| 8669 | after all other options have been applied. |
| 8670 | <DT><B>-S</B> <I>suffix</I><DD> |
| 8671 | <I>suffix</I> is appended to each possible completion |
| 8672 | after all other options have been applied. |
| 8673 | |
| 8674 | </DL> |
| 8675 | <P> |
| 8676 | |
| 8677 | The return value is true unless an invalid option is supplied, an option |
| 8678 | other than <B>-p</B> or <B>-r</B> is supplied without a <I>name</I> |
| 8679 | argument, an attempt is made to remove a completion specification for |
| 8680 | a <I>name</I> for which no specification exists, or |
| 8681 | an error occurs adding a completion specification. |
| 8682 | </DL> |
| 8683 | |
| 8684 | <DT><B>compopt</B> [<B>-o</B> <I>option</I>] [<B>+o</B> <I>option</I>] [<I>name</I>]<DD> |
| 8685 | Modify completion options for each <I>name</I> according to the |
| 8686 | <I>option</I>s, or for the |
| 8687 | currently-execution completion if no <I>name</I>s are supplied. |
| 8688 | If no <I>option</I>s are given, display the completion options for each |
| 8689 | <I>name</I> or the current completion. |
| 8690 | The possible values of <I>option</I> are those valid for the <B>complete</B> |
| 8691 | builtin described above. |
| 8692 | </DL> |
| 8693 | <P> |
| 8694 | |
| 8695 | The return value is true unless an invalid option is supplied, an attempt |
| 8696 | is made to modify the options for a <I>name</I> for which no completion |
| 8697 | specification exists, or an output error occurs. |
| 8698 | <DL COMPACT> |
| 8699 | <DT><B>continue</B> [<I>n</I>]<DD> |
| 8700 | Resume the next iteration of the enclosing |
| 8701 | <B>for</B>, |
| 8702 | |
| 8703 | <B>while</B>, |
| 8704 | |
| 8705 | <B>until</B>, |
| 8706 | |
| 8707 | or |
| 8708 | <B>select</B> |
| 8709 | |
| 8710 | loop. |
| 8711 | If |
| 8712 | <I>n</I> |
| 8713 | |
| 8714 | is specified, resume at the <I>n</I>th enclosing loop. |
| 8715 | <I>n</I> |
| 8716 | |
| 8717 | must be >= 1. If |
| 8718 | <I>n</I> |
| 8719 | |
| 8720 | is greater than the number of enclosing loops, the last enclosing loop |
| 8721 | (the ``top-level'' loop) is resumed. |
| 8722 | The return value is 0 unless <I>n</I> is not greater than or equal to 1. |
| 8723 | <DT><B>declare</B> [<B>-aAfFilrtux</B>] [<B>-p</B>] [<I>name</I>[=<I>value</I>] ...]<DD> |
| 8724 | |
| 8725 | <DT><B>typeset</B> [<B>-aAfFilrtux</B>] [<B>-p</B>] [<I>name</I>[=<I>value</I>] ...]<DD> |
| 8726 | |
| 8727 | Declare variables and/or give them attributes. |
| 8728 | If no <I>name</I>s are given then display the values of variables. |
| 8729 | The |
| 8730 | <B>-p</B> |
| 8731 | |
| 8732 | option will display the attributes and values of each |
| 8733 | <I>name</I>. |
| 8734 | |
| 8735 | When |
| 8736 | <B>-p</B> |
| 8737 | |
| 8738 | is used with <I>name</I> arguments, additional options are ignored. |
| 8739 | When |
| 8740 | <B>-p</B> |
| 8741 | |
| 8742 | is supplied without <I>name</I> arguments, it will display the attributes |
| 8743 | and values of all variables having the attributes specified by the |
| 8744 | additional options. |
| 8745 | If no other options are supplied with <B>-p</B>, <B>declare</B> will display |
| 8746 | the attributes and values of all shell variables. The <B>-f</B> option |
| 8747 | will restrict the display to shell functions. |
| 8748 | The |
| 8749 | <B>-F</B> |
| 8750 | |
| 8751 | option inhibits the display of function definitions; only the |
| 8752 | function name and attributes are printed. |
| 8753 | If the <B>extdebug</B> shell option is enabled using <B>shopt</B>, |
| 8754 | the source file name and line number where the function is defined |
| 8755 | are displayed as well. The |
| 8756 | <B>-F</B> |
| 8757 | |
| 8758 | option implies |
| 8759 | <B>-f</B>. |
| 8760 | |
| 8761 | The following options can |
| 8762 | be used to restrict output to variables with the specified attribute or |
| 8763 | to give variables attributes: |
| 8764 | <DL COMPACT><DT><DD> |
| 8765 | |
| 8766 | <DL COMPACT> |
| 8767 | <DT><B>-a</B> |
| 8768 | |
| 8769 | <DD> |
| 8770 | Each <I>name</I> is an indexed array variable (see |
| 8771 | <B>Arrays</B> |
| 8772 | |
| 8773 | above). |
| 8774 | <DT><B>-A</B> |
| 8775 | |
| 8776 | <DD> |
| 8777 | Each <I>name</I> is an associative array variable (see |
| 8778 | <B>Arrays</B> |
| 8779 | |
| 8780 | above). |
| 8781 | <DT><B>-f</B> |
| 8782 | |
| 8783 | <DD> |
| 8784 | Use function names only. |
| 8785 | <DT><B>-i</B> |
| 8786 | |
| 8787 | <DD> |
| 8788 | The variable is treated as an integer; arithmetic evaluation (see |
| 8789 | <FONT SIZE=-1><B>ARITHMETIC EVALUATION ) </B> |
| 8790 | |
| 8791 | </FONT> |
| 8792 | is performed when the variable is assigned a value. |
| 8793 | <DT><B>-l</B> |
| 8794 | |
| 8795 | <DD> |
| 8796 | When the variable is assigned a value, all upper-case characters are |
| 8797 | converted to lower-case. |
| 8798 | The upper-case attribute is disabled. |
| 8799 | <DT><B>-r</B> |
| 8800 | |
| 8801 | <DD> |
| 8802 | Make <I>name</I>s readonly. These names cannot then be assigned values |
| 8803 | by subsequent assignment statements or unset. |
| 8804 | <DT><B>-t</B> |
| 8805 | |
| 8806 | <DD> |
| 8807 | Give each <I>name</I> the <I>trace</I> attribute. |
| 8808 | Traced functions inherit the <B>DEBUG</B> and <B>RETURN</B> traps from |
| 8809 | the calling shell. |
| 8810 | The trace attribute has no special meaning for variables. |
| 8811 | <DT><B>-u</B> |
| 8812 | |
| 8813 | <DD> |
| 8814 | When the variable is assigned a value, all lower-case characters are |
| 8815 | converted to upper-case. |
| 8816 | The lower-case attribute is disabled. |
| 8817 | <DT><B>-x</B> |
| 8818 | |
| 8819 | <DD> |
| 8820 | Mark <I>name</I>s for export to subsequent commands via the environment. |
| 8821 | |
| 8822 | </DL> |
| 8823 | <P> |
| 8824 | |
| 8825 | Using `+' instead of `-' |
| 8826 | turns off the attribute instead, |
| 8827 | with the exceptions that <B>+a</B> |
| 8828 | may not be used to destroy an array variable and <B>+r will not |
| 8829 | remove the readonly attribute. |
| 8830 | When used in a function, |
| 8831 | makes each |
| 8832 | </B><I>name</I> local, as with the |
| 8833 | <B>local</B> |
| 8834 | |
| 8835 | command. |
| 8836 | If a variable name is followed by =<I>value</I>, the value of |
| 8837 | the variable is set to <I>value</I>. |
| 8838 | The return value is 0 unless an invalid option is encountered, |
| 8839 | an attempt is made to define a function using |
| 8840 | |
| 8841 | <TT>-f foo=bar</TT>, |
| 8842 | an attempt is made to assign a value to a readonly variable, |
| 8843 | an attempt is made to assign a value to an array variable without |
| 8844 | using the compound assignment syntax (see |
| 8845 | <B>Arrays</B> |
| 8846 | |
| 8847 | above), one of the <I>names</I> is not a valid shell variable name, |
| 8848 | an attempt is made to turn off readonly status for a readonly variable, |
| 8849 | an attempt is made to turn off array status for an array variable, |
| 8850 | or an attempt is made to display a non-existent function with <B>-f</B>. |
| 8851 | </DL> |
| 8852 | |
| 8853 | <DT><B>dirs [+</B><I>n</I>] [-<I>n</I>] [<B>-cplv</B>] |
| 8854 | |
| 8855 | <DD> |
| 8856 | Without options, displays the list of currently remembered directories. |
| 8857 | The default display is on a single line with directory names separated |
| 8858 | by spaces. |
| 8859 | Directories are added to the list with the |
| 8860 | <B>pushd</B> |
| 8861 | |
| 8862 | command; the |
| 8863 | <B>popd</B> |
| 8864 | |
| 8865 | command removes entries from the list. |
| 8866 | <DL COMPACT><DT><DD> |
| 8867 | |
| 8868 | <DL COMPACT> |
| 8869 | <DT><B>+</B><I>n</I><DD> |
| 8870 | Displays the <I>n</I>th entry counting from the left of the list |
| 8871 | shown by |
| 8872 | <B>dirs</B> |
| 8873 | |
| 8874 | when invoked without options, starting with zero. |
| 8875 | <DT><B>-</B><I>n</I><DD> |
| 8876 | Displays the <I>n</I>th entry counting from the right of the list |
| 8877 | shown by |
| 8878 | <B>dirs</B> |
| 8879 | |
| 8880 | when invoked without options, starting with zero. |
| 8881 | <DT><B>-c</B> |
| 8882 | |
| 8883 | <DD> |
| 8884 | Clears the directory stack by deleting all of the entries. |
| 8885 | <DT><B>-l</B> |
| 8886 | |
| 8887 | <DD> |
| 8888 | Produces a longer listing; the default listing format uses a |
| 8889 | tilde to denote the home directory. |
| 8890 | <DT><B>-p</B> |
| 8891 | |
| 8892 | <DD> |
| 8893 | Print the directory stack with one entry per line. |
| 8894 | <DT><B>-v</B> |
| 8895 | |
| 8896 | <DD> |
| 8897 | Print the directory stack with one entry per line, |
| 8898 | prefixing each entry with its index in the stack. |
| 8899 | |
| 8900 | </DL> |
| 8901 | <P> |
| 8902 | |
| 8903 | The return value is 0 unless an |
| 8904 | invalid option is supplied or <I>n</I> indexes beyond the end |
| 8905 | of the directory stack. |
| 8906 | </DL> |
| 8907 | |
| 8908 | <DT><B>disown</B> [<B>-ar</B>] [<B>-h</B>] [<I>jobspec</I> ...]<DD> |
| 8909 | Without options, each |
| 8910 | <I>jobspec</I> |
| 8911 | |
| 8912 | is removed from the table of active jobs. |
| 8913 | If |
| 8914 | <I>jobspec</I> |
| 8915 | |
| 8916 | is not present, and neither <B>-a nor -r</B> is supplied, |
| 8917 | the shell's notion of the <I>current job</I> is used. |
| 8918 | If the <B>-h</B> option is given, each |
| 8919 | <I>jobspec</I> |
| 8920 | |
| 8921 | is not removed from the table, but is marked so that |
| 8922 | <FONT SIZE=-1><B>SIGHUP</B> |
| 8923 | |
| 8924 | </FONT> |
| 8925 | is not sent to the job if the shell receives a |
| 8926 | <FONT SIZE=-1><B>SIGHUP</B>. |
| 8927 | |
| 8928 | </FONT> |
| 8929 | If no |
| 8930 | <I>jobspec</I> |
| 8931 | |
| 8932 | is present, and neither the |
| 8933 | <B>-a</B> |
| 8934 | |
| 8935 | nor the |
| 8936 | <B>-r</B> |
| 8937 | |
| 8938 | option is supplied, the <I>current job</I> is used. |
| 8939 | If no |
| 8940 | <I>jobspec</I> |
| 8941 | |
| 8942 | is supplied, the |
| 8943 | <B>-a</B> |
| 8944 | |
| 8945 | option means to remove or mark all jobs; the |
| 8946 | <B>-r</B> |
| 8947 | |
| 8948 | option without a |
| 8949 | <I>jobspec</I> |
| 8950 | |
| 8951 | argument restricts operation to running jobs. |
| 8952 | The return value is 0 unless a |
| 8953 | <I>jobspec</I> |
| 8954 | |
| 8955 | does not specify a valid job. |
| 8956 | <DT><B>echo</B> [<B>-neE</B>] [<I>arg</I> ...]<DD> |
| 8957 | Output the <I>arg</I>s, separated by spaces, followed by a newline. |
| 8958 | The return status is always 0. |
| 8959 | If <B>-n</B> is specified, the trailing newline is |
| 8960 | suppressed. If the <B>-e</B> option is given, interpretation of |
| 8961 | the following backslash-escaped characters is enabled. The |
| 8962 | <B>-E</B> |
| 8963 | |
| 8964 | option disables the interpretation of these escape characters, |
| 8965 | even on systems where they are interpreted by default. |
| 8966 | The <B>xpg_echo</B> shell option may be used to |
| 8967 | dynamically determine whether or not <B>echo</B> expands these |
| 8968 | escape characters by default. |
| 8969 | <B>echo</B> |
| 8970 | |
| 8971 | does not interpret <B>--</B> to mean the end of options. |
| 8972 | <B>echo</B> |
| 8973 | |
| 8974 | interprets the following escape sequences: |
| 8975 | <DL COMPACT><DT><DD> |
| 8976 | |
| 8977 | <DL COMPACT> |
| 8978 | <DT><B>\a</B> |
| 8979 | |
| 8980 | <DD> |
| 8981 | alert (bell) |
| 8982 | <DT><B>\b</B> |
| 8983 | |
| 8984 | <DD> |
| 8985 | backspace |
| 8986 | <DT><B>\c</B> |
| 8987 | |
| 8988 | <DD> |
| 8989 | suppress further output |
| 8990 | <DT><B>\e</B> |
| 8991 | |
| 8992 | <DD> |
| 8993 | an escape character |
| 8994 | <DT><B>\f</B> |
| 8995 | |
| 8996 | <DD> |
| 8997 | form feed |
| 8998 | <DT><B>\n</B> |
| 8999 | |
| 9000 | <DD> |
| 9001 | new line |
| 9002 | <DT><B>\r</B> |
| 9003 | |
| 9004 | <DD> |
| 9005 | carriage return |
| 9006 | <DT><B>\t</B> |
| 9007 | |
| 9008 | <DD> |
| 9009 | horizontal tab |
| 9010 | <DT><B>\v</B> |
| 9011 | |
| 9012 | <DD> |
| 9013 | vertical tab |
| 9014 | <DT><B>\\</B> |
| 9015 | |
| 9016 | <DD> |
| 9017 | backslash |
| 9018 | <DT><B>\0</B><I>nnn</I> |
| 9019 | |
| 9020 | <DD> |
| 9021 | the eight-bit character whose value is the octal value <I>nnn</I> |
| 9022 | (zero to three octal digits) |
| 9023 | <DT><B>\x</B><I>HH</I> |
| 9024 | |
| 9025 | <DD> |
| 9026 | the eight-bit character whose value is the hexadecimal value <I>HH</I> |
| 9027 | (one or two hex digits) |
| 9028 | |
| 9029 | </DL></DL> |
| 9030 | |
| 9031 | <DT><B>enable</B> [<B>-a</B>] [<B>-dnps</B>] [<B>-f</B> <I>filename</I>] [<I>name</I> ...]<DD> |
| 9032 | Enable and disable builtin shell commands. |
| 9033 | Disabling a builtin allows a disk command which has the same name |
| 9034 | as a shell builtin to be executed without specifying a full pathname, |
| 9035 | even though the shell normally searches for builtins before disk commands. |
| 9036 | If <B>-n</B> is used, each <I>name</I> |
| 9037 | is disabled; otherwise, |
| 9038 | <I>names</I> are enabled. For example, to use the |
| 9039 | <B>test</B> |
| 9040 | |
| 9041 | binary found via the |
| 9042 | <FONT SIZE=-1><B>PATH</B> |
| 9043 | |
| 9044 | </FONT> |
| 9045 | instead of the shell builtin version, run |
| 9046 | <TT>enable -n test</TT>. |
| 9047 | |
| 9048 | The |
| 9049 | <B>-f</B> |
| 9050 | |
| 9051 | option means to load the new builtin command |
| 9052 | <I>name</I> |
| 9053 | |
| 9054 | from shared object |
| 9055 | <I>filename</I>, |
| 9056 | |
| 9057 | on systems that support dynamic loading. The |
| 9058 | <B>-d</B> |
| 9059 | |
| 9060 | option will delete a builtin previously loaded with |
| 9061 | <B>-f</B>. |
| 9062 | |
| 9063 | If no <I>name</I> arguments are given, or if the |
| 9064 | <B>-p</B> |
| 9065 | |
| 9066 | option is supplied, a list of shell builtins is printed. |
| 9067 | With no other option arguments, the list consists of all enabled |
| 9068 | shell builtins. |
| 9069 | If <B>-n</B> is supplied, only disabled builtins are printed. |
| 9070 | If <B>-a</B> is supplied, the list printed includes all builtins, with an |
| 9071 | indication of whether or not each is enabled. |
| 9072 | If <B>-s</B> is supplied, the output is restricted to the POSIX |
| 9073 | <I>special</I> builtins. |
| 9074 | The return value is 0 unless a |
| 9075 | <I>name</I> |
| 9076 | |
| 9077 | is not a shell builtin or there is an error loading a new builtin |
| 9078 | from a shared object. |
| 9079 | <DT><B>eval</B> [<I>arg</I> ...]<DD> |
| 9080 | The <I>arg</I>s are read and concatenated together into a single |
| 9081 | command. This command is then read and executed by the shell, and |
| 9082 | its exit status is returned as the value of |
| 9083 | <B>eval</B>. |
| 9084 | |
| 9085 | If there are no |
| 9086 | <I>args</I>, |
| 9087 | |
| 9088 | or only null arguments, |
| 9089 | <B>eval</B> |
| 9090 | |
| 9091 | returns 0. |
| 9092 | <DT><B>exec</B> [<B>-cl</B>] [<B>-a</B> <I>name</I>] [<I>command</I> [<I>arguments</I>]]<DD> |
| 9093 | If |
| 9094 | <I>command</I> |
| 9095 | |
| 9096 | is specified, it replaces the shell. |
| 9097 | No new process is created. The |
| 9098 | <I>arguments</I> |
| 9099 | |
| 9100 | become the arguments to <I>command</I>. |
| 9101 | If the |
| 9102 | <B>-l</B> |
| 9103 | |
| 9104 | option is supplied, |
| 9105 | the shell places a dash at the beginning of the zeroth argument passed to |
| 9106 | <I>command</I>. |
| 9107 | |
| 9108 | This is what |
| 9109 | <I>login</I>(1) |
| 9110 | |
| 9111 | does. The |
| 9112 | <B>-c</B> |
| 9113 | |
| 9114 | option causes |
| 9115 | <I>command</I> |
| 9116 | |
| 9117 | to be executed with an empty environment. If |
| 9118 | <B>-a</B> |
| 9119 | |
| 9120 | is supplied, the shell passes |
| 9121 | <I>name</I> |
| 9122 | |
| 9123 | as the zeroth argument to the executed command. If |
| 9124 | <I>command</I> |
| 9125 | |
| 9126 | cannot be executed for some reason, a non-interactive shell exits, |
| 9127 | unless the shell option |
| 9128 | <B>execfail</B> |
| 9129 | |
| 9130 | is enabled, in which case it returns failure. |
| 9131 | An interactive shell returns failure if the file cannot be executed. |
| 9132 | If |
| 9133 | <I>command</I> |
| 9134 | |
| 9135 | is not specified, any redirections take effect in the current shell, |
| 9136 | and the return status is 0. If there is a redirection error, the |
| 9137 | return status is 1. |
| 9138 | <DT><B>exit</B> [<I>n</I>]<DD> |
| 9139 | Cause the shell to exit |
| 9140 | with a status of <I>n</I>. If |
| 9141 | <I>n</I> |
| 9142 | |
| 9143 | is omitted, the exit status |
| 9144 | is that of the last command executed. |
| 9145 | A trap on |
| 9146 | <FONT SIZE=-1><B>EXIT</B> |
| 9147 | |
| 9148 | </FONT> |
| 9149 | is executed before the shell terminates. |
| 9150 | <DT><B>export</B> [<B>-fn</B>] [<I>name</I>[=<I>word</I>]] ...<DD> |
| 9151 | |
| 9152 | <DT><B>export -p</B> |
| 9153 | |
| 9154 | <DD> |
| 9155 | |
| 9156 | The supplied |
| 9157 | <I>names</I> |
| 9158 | |
| 9159 | are marked for automatic export to the environment of |
| 9160 | subsequently executed commands. If the |
| 9161 | <B>-f</B> |
| 9162 | |
| 9163 | option is given, |
| 9164 | the |
| 9165 | <I>names</I> |
| 9166 | |
| 9167 | refer to functions. |
| 9168 | If no |
| 9169 | <I>names</I> |
| 9170 | |
| 9171 | are given, or if the |
| 9172 | <B>-p</B> |
| 9173 | |
| 9174 | option is supplied, a list |
| 9175 | of all names that are exported in this shell is printed. |
| 9176 | The |
| 9177 | <B>-n</B> |
| 9178 | |
| 9179 | option causes the export property to be removed from each |
| 9180 | <I>name</I>. |
| 9181 | If a variable name is followed by =<I>word</I>, the value of |
| 9182 | the variable is set to <I>word</I>. |
| 9183 | <B>export</B> |
| 9184 | |
| 9185 | returns an exit status of 0 unless an invalid option is |
| 9186 | encountered, |
| 9187 | one of the <I>names</I> is not a valid shell variable name, or |
| 9188 | <B>-f</B> |
| 9189 | |
| 9190 | is supplied with a |
| 9191 | <I>name</I> |
| 9192 | |
| 9193 | that is not a function. |
| 9194 | <DT><B>fc</B> [<B>-e</B> <I>ename</I>] [<B>-lnr</B>] [<I>first</I>] [<I>last</I>]<DD> |
| 9195 | |
| 9196 | <DT><B>fc</B> <B>-s</B> [<I>pat</I>=<I>rep</I>] [<I>cmd</I>]<DD> |
| 9197 | |
| 9198 | Fix Command. In the first form, a range of commands from |
| 9199 | <I>first</I> |
| 9200 | |
| 9201 | to |
| 9202 | <I>last</I> |
| 9203 | |
| 9204 | is selected from the history list. |
| 9205 | <I>First</I> |
| 9206 | |
| 9207 | and |
| 9208 | <I>last</I> |
| 9209 | |
| 9210 | may be specified as a string (to locate the last command beginning |
| 9211 | with that string) or as a number (an index into the history list, |
| 9212 | where a negative number is used as an offset from the current |
| 9213 | command number). If |
| 9214 | <I>last</I> |
| 9215 | |
| 9216 | is not specified it is set to |
| 9217 | the current command for listing (so that |
| 9218 | |
| 9219 | <TT>fc -l -10</TT> |
| 9220 | prints the last 10 commands) and to |
| 9221 | <I>first</I> |
| 9222 | |
| 9223 | otherwise. |
| 9224 | If |
| 9225 | <I>first</I> |
| 9226 | |
| 9227 | is not specified it is set to the previous |
| 9228 | command for editing and -16 for listing. |
| 9229 | <P> |
| 9230 | The |
| 9231 | <B>-n</B> |
| 9232 | |
| 9233 | option suppresses |
| 9234 | the command numbers when listing. The |
| 9235 | <B>-r</B> |
| 9236 | |
| 9237 | option reverses the order of |
| 9238 | the commands. If the |
| 9239 | <B>-l</B> |
| 9240 | |
| 9241 | option is given, |
| 9242 | the commands are listed on |
| 9243 | standard output. Otherwise, the editor given by |
| 9244 | <I>ename</I> |
| 9245 | |
| 9246 | is invoked |
| 9247 | on a file containing those commands. If |
| 9248 | <I>ename</I> |
| 9249 | |
| 9250 | is not given, the |
| 9251 | value of the |
| 9252 | <FONT SIZE=-1><B>FCEDIT</B> |
| 9253 | |
| 9254 | </FONT> |
| 9255 | variable is used, and |
| 9256 | the value of |
| 9257 | <FONT SIZE=-1><B>EDITOR</B> |
| 9258 | |
| 9259 | </FONT> |
| 9260 | if |
| 9261 | <FONT SIZE=-1><B>FCEDIT</B> |
| 9262 | |
| 9263 | </FONT> |
| 9264 | is not set. If neither variable is set, |
| 9265 | |
| 9266 | <I>vi</I> |
| 9267 | |
| 9268 | is used. When editing is complete, the edited commands are |
| 9269 | echoed and executed. |
| 9270 | <P> |
| 9271 | In the second form, <I>command</I> is re-executed after each instance |
| 9272 | of <I>pat</I> is replaced by <I>rep</I>. |
| 9273 | A useful alias to use with this is |
| 9274 | |
| 9275 | <TT>r='fc -s'</TT>, |
| 9276 | so that typing |
| 9277 | |
| 9278 | <TT>r cc</TT> |
| 9279 | runs the last command beginning with |
| 9280 | |
| 9281 | <TT>cc</TT> |
| 9282 | and typing |
| 9283 | |
| 9284 | <TT>r</TT> |
| 9285 | re-executes the last command. |
| 9286 | <P> |
| 9287 | If the first form is used, the return value is 0 unless an invalid |
| 9288 | option is encountered or |
| 9289 | <I>first</I> |
| 9290 | |
| 9291 | or |
| 9292 | <I>last</I> |
| 9293 | |
| 9294 | specify history lines out of range. |
| 9295 | If the |
| 9296 | <B>-e</B> |
| 9297 | |
| 9298 | option is supplied, the return value is the value of the last |
| 9299 | command executed or failure if an error occurs with the temporary |
| 9300 | file of commands. If the second form is used, the return status |
| 9301 | is that of the command re-executed, unless |
| 9302 | <I>cmd</I> |
| 9303 | |
| 9304 | does not specify a valid history line, in which case |
| 9305 | <B>fc</B> |
| 9306 | |
| 9307 | returns failure. |
| 9308 | <DT><B>fg</B> [<I>jobspec</I>]<DD> |
| 9309 | Resume |
| 9310 | <I>jobspec</I> |
| 9311 | |
| 9312 | in the foreground, and make it the current job. |
| 9313 | If |
| 9314 | <I>jobspec</I> |
| 9315 | |
| 9316 | is not present, the shell's notion of the <I>current job</I> is used. |
| 9317 | The return value is that of the command placed into the foreground, |
| 9318 | or failure if run when job control is disabled or, when run with |
| 9319 | job control enabled, if |
| 9320 | <I>jobspec</I> |
| 9321 | |
| 9322 | does not specify a valid job or |
| 9323 | <I>jobspec</I> |
| 9324 | |
| 9325 | specifies a job that was started without job control. |
| 9326 | <DT><B>getopts</B> <I>optstring</I> <I>name</I> [<I>args</I>]<DD> |
| 9327 | <B>getopts</B> |
| 9328 | |
| 9329 | is used by shell procedures to parse positional parameters. |
| 9330 | <I>optstring</I> |
| 9331 | |
| 9332 | contains the option characters to be recognized; if a character |
| 9333 | is followed by a colon, the option is expected to have an |
| 9334 | argument, which should be separated from it by white space. |
| 9335 | The colon and question mark characters may not be used as |
| 9336 | option characters. |
| 9337 | Each time it is invoked, |
| 9338 | <B>getopts</B> |
| 9339 | |
| 9340 | places the next option in the shell variable |
| 9341 | <I>name</I>, |
| 9342 | |
| 9343 | initializing |
| 9344 | <I>name</I> |
| 9345 | |
| 9346 | if it does not exist, |
| 9347 | and the index of the next argument to be processed into the |
| 9348 | variable |
| 9349 | <FONT SIZE=-1><B>OPTIND</B>. |
| 9350 | |
| 9351 | </FONT> |
| 9352 | <FONT SIZE=-1><B>OPTIND</B> |
| 9353 | |
| 9354 | </FONT> |
| 9355 | is initialized to 1 each time the shell or a shell script |
| 9356 | is invoked. When an option requires an argument, |
| 9357 | <B>getopts</B> |
| 9358 | |
| 9359 | places that argument into the variable |
| 9360 | <FONT SIZE=-1><B>OPTARG</B>. |
| 9361 | |
| 9362 | </FONT> |
| 9363 | The shell does not reset |
| 9364 | <FONT SIZE=-1><B>OPTIND</B> |
| 9365 | |
| 9366 | </FONT> |
| 9367 | automatically; it must be manually reset between multiple |
| 9368 | calls to |
| 9369 | <B>getopts</B> |
| 9370 | |
| 9371 | within the same shell invocation if a new set of parameters |
| 9372 | is to be used. |
| 9373 | <P> |
| 9374 | When the end of options is encountered, <B>getopts</B> exits with a |
| 9375 | return value greater than zero. |
| 9376 | <B>OPTIND</B> is set to the index of the first non-option argument, |
| 9377 | and <B>name</B> is set to ?. |
| 9378 | <P> |
| 9379 | <B>getopts</B> |
| 9380 | |
| 9381 | normally parses the positional parameters, but if more arguments are |
| 9382 | given in |
| 9383 | <I>args</I>, |
| 9384 | |
| 9385 | <B>getopts</B> |
| 9386 | |
| 9387 | parses those instead. |
| 9388 | <P> |
| 9389 | <B>getopts</B> |
| 9390 | |
| 9391 | can report errors in two ways. If the first character of |
| 9392 | <I>optstring</I> |
| 9393 | |
| 9394 | is a colon, |
| 9395 | <I>silent</I> |
| 9396 | |
| 9397 | error reporting is used. In normal operation diagnostic messages |
| 9398 | are printed when invalid options or missing option arguments are |
| 9399 | encountered. |
| 9400 | If the variable |
| 9401 | <FONT SIZE=-1><B>OPTERR</B> |
| 9402 | |
| 9403 | </FONT> |
| 9404 | is set to 0, no error messages will be displayed, even if the first |
| 9405 | character of |
| 9406 | <I>optstring</I> |
| 9407 | |
| 9408 | is not a colon. |
| 9409 | <P> |
| 9410 | If an invalid option is seen, |
| 9411 | <B>getopts</B> |
| 9412 | |
| 9413 | places ? into |
| 9414 | <I>name</I> |
| 9415 | |
| 9416 | and, if not silent, |
| 9417 | prints an error message and unsets |
| 9418 | <FONT SIZE=-1><B>OPTARG</B>. |
| 9419 | |
| 9420 | </FONT> |
| 9421 | If |
| 9422 | <B>getopts</B> |
| 9423 | |
| 9424 | is silent, |
| 9425 | the option character found is placed in |
| 9426 | <FONT SIZE=-1><B>OPTARG</B> |
| 9427 | |
| 9428 | </FONT> |
| 9429 | and no diagnostic message is printed. |
| 9430 | <P> |
| 9431 | If a required argument is not found, and |
| 9432 | <B>getopts</B> |
| 9433 | |
| 9434 | is not silent, |
| 9435 | a question mark (<B>?</B>) is placed in |
| 9436 | <I>name</I>, |
| 9437 | |
| 9438 | <FONT SIZE=-1><B>OPTARG</B> |
| 9439 | |
| 9440 | </FONT> |
| 9441 | is unset, and a diagnostic message is printed. |
| 9442 | If |
| 9443 | <B>getopts</B> |
| 9444 | |
| 9445 | is silent, then a colon (<B>:</B>) is placed in |
| 9446 | <I>name</I> |
| 9447 | |
| 9448 | and |
| 9449 | <FONT SIZE=-1><B>OPTARG</B> |
| 9450 | |
| 9451 | </FONT> |
| 9452 | is set to the option character found. |
| 9453 | <P> |
| 9454 | <B>getopts</B> |
| 9455 | |
| 9456 | returns true if an option, specified or unspecified, is found. |
| 9457 | It returns false if the end of options is encountered or an |
| 9458 | error occurs. |
| 9459 | <DT><B>hash</B> [<B>-lr</B>] [<B>-p</B> <I>filename</I>] [<B>-dt</B>] [<I>name</I>]<DD> |
| 9460 | For each |
| 9461 | <I>name</I>, |
| 9462 | |
| 9463 | the full file name of the command is determined by searching |
| 9464 | the directories in |
| 9465 | <B>$PATH</B> |
| 9466 | |
| 9467 | and remembered. |
| 9468 | If the |
| 9469 | <B>-p</B> |
| 9470 | |
| 9471 | option is supplied, no path search is performed, and |
| 9472 | <I>filename</I> |
| 9473 | |
| 9474 | is used as the full file name of the command. |
| 9475 | The |
| 9476 | <B>-r</B> |
| 9477 | |
| 9478 | option causes the shell to forget all |
| 9479 | remembered locations. |
| 9480 | The |
| 9481 | <B>-d</B> |
| 9482 | |
| 9483 | option causes the shell to forget the remembered location of each <I>name</I>. |
| 9484 | If the |
| 9485 | <B>-t</B> |
| 9486 | |
| 9487 | option is supplied, the full pathname to which each <I>name</I> corresponds |
| 9488 | is printed. If multiple <I>name</I> arguments are supplied with <B>-t</B>, |
| 9489 | the <I>name</I> is printed before the hashed full pathname. |
| 9490 | The |
| 9491 | <B>-l</B> |
| 9492 | |
| 9493 | option causes output to be displayed in a format that may be reused as input. |
| 9494 | If no arguments are given, or if only <B>-l</B> is supplied, |
| 9495 | information about remembered commands is printed. |
| 9496 | The return status is true unless a |
| 9497 | <I>name</I> |
| 9498 | |
| 9499 | is not found or an invalid option is supplied. |
| 9500 | <DT><B>help</B> [<B>-dms</B>] [<I>pattern</I>]<DD> |
| 9501 | Display helpful information about builtin commands. If |
| 9502 | <I>pattern</I> |
| 9503 | |
| 9504 | is specified, |
| 9505 | <B>help</B> |
| 9506 | |
| 9507 | gives detailed help on all commands matching |
| 9508 | <I>pattern</I>; |
| 9509 | |
| 9510 | otherwise help for all the builtins and shell control structures |
| 9511 | is printed. |
| 9512 | <DL COMPACT><DT><DD> |
| 9513 | |
| 9514 | <DL COMPACT> |
| 9515 | <DT><B>-d</B> |
| 9516 | |
| 9517 | <DD> |
| 9518 | Display a short description of each <I>pattern</I> |
| 9519 | <DT><B> -m</B> |
| 9520 | |
| 9521 | <DD> |
| 9522 | Display the description of each <I>pattern</I> in a manpage-like format |
| 9523 | <DT><B>-s</B> |
| 9524 | |
| 9525 | <DD> |
| 9526 | Display only a short usage synopsis for each <I>pattern</I> |
| 9527 | |
| 9528 | </DL></DL> |
| 9529 | |
| 9530 | The return status is 0 unless no command matches |
| 9531 | <I>pattern</I>. |
| 9532 | |
| 9533 | <DT><B>history [</B><I>n</I>]<DD> |
| 9534 | |
| 9535 | <DT><B>history</B> <B>-c</B><DD> |
| 9536 | <DT><B>history -d</B> <I>offset</I><DD> |
| 9537 | <DT><B>history</B> <B>-anrw</B> [<I>filename</I>]<DD> |
| 9538 | <DT><B>history</B> <B>-p</B> <I>arg</I> [<I>arg ...</I>]<DD> |
| 9539 | <DT><B>history</B> <B>-s</B> <I>arg</I> [<I>arg ...</I>]<DD> |
| 9540 | |
| 9541 | With no options, display the command |
| 9542 | history list with line numbers. Lines listed |
| 9543 | with a |
| 9544 | <B>*</B> |
| 9545 | |
| 9546 | have been modified. An argument of |
| 9547 | <I>n</I> |
| 9548 | |
| 9549 | lists only the last |
| 9550 | <I>n</I> |
| 9551 | |
| 9552 | lines. |
| 9553 | If the shell variable <B>HISTTIMEFORMAT</B> is set and not null, |
| 9554 | it is used as a format string for <I>strftime</I>(3) to display |
| 9555 | the time stamp associated with each displayed history entry. |
| 9556 | No intervening blank is printed between the formatted time stamp |
| 9557 | and the history line. |
| 9558 | If <I>filename</I> is supplied, it is used as the |
| 9559 | name of the history file; if not, the value of |
| 9560 | <FONT SIZE=-1><B>HISTFILE</B> |
| 9561 | |
| 9562 | </FONT> |
| 9563 | is used. Options, if supplied, have the following meanings: |
| 9564 | <DL COMPACT><DT><DD> |
| 9565 | |
| 9566 | <DL COMPACT> |
| 9567 | <DT><B>-c</B> |
| 9568 | |
| 9569 | <DD> |
| 9570 | Clear the history list by deleting all the entries. |
| 9571 | <DT><B>-d</B> <I>offset</I><DD> |
| 9572 | Delete the history entry at position <I>offset</I>. |
| 9573 | <DT><B>-a</B> |
| 9574 | |
| 9575 | <DD> |
| 9576 | Append the ``new'' history lines (history lines entered since the |
| 9577 | beginning of the current <B>bash</B> session) to the history file. |
| 9578 | <DT><B>-n</B> |
| 9579 | |
| 9580 | <DD> |
| 9581 | Read the history lines not already read from the history |
| 9582 | file into the current history list. These are lines |
| 9583 | appended to the history file since the beginning of the |
| 9584 | current <B>bash</B> session. |
| 9585 | <DT><B>-r</B> |
| 9586 | |
| 9587 | <DD> |
| 9588 | Read the contents of the history file |
| 9589 | and use them as the current history. |
| 9590 | <DT><B>-w</B> |
| 9591 | |
| 9592 | <DD> |
| 9593 | Write the current history to the history file, overwriting the |
| 9594 | history file's contents. |
| 9595 | <DT><B>-p</B> |
| 9596 | |
| 9597 | <DD> |
| 9598 | Perform history substitution on the following <I>args</I> and display |
| 9599 | the result on the standard output. |
| 9600 | Does not store the results in the history list. |
| 9601 | Each <I>arg</I> must be quoted to disable normal history expansion. |
| 9602 | <DT><B>-s</B> |
| 9603 | |
| 9604 | <DD> |
| 9605 | Store the |
| 9606 | <I>args</I> |
| 9607 | |
| 9608 | in the history list as a single entry. The last command in the |
| 9609 | history list is removed before the |
| 9610 | <I>args</I> |
| 9611 | |
| 9612 | are added. |
| 9613 | |
| 9614 | </DL> |
| 9615 | <P> |
| 9616 | |
| 9617 | If the <B>HISTTIMEFORMAT</B> is set, the time stamp information |
| 9618 | associated with each history entry is written to the history file, |
| 9619 | marked with the history comment character. |
| 9620 | When the history file is read, lines beginning with the history |
| 9621 | comment character followed immediately by a digit are interpreted |
| 9622 | as timestamps for the previous history line. |
| 9623 | The return value is 0 unless an invalid option is encountered, an |
| 9624 | error occurs while reading or writing the history file, an invalid |
| 9625 | <I>offset</I> is supplied as an argument to <B>-d</B>, or the |
| 9626 | history expansion supplied as an argument to <B>-p</B> fails. |
| 9627 | </DL> |
| 9628 | |
| 9629 | <DT><B>jobs</B> [<B>-lnprs</B>] [ <I>jobspec</I> ... ]<DD> |
| 9630 | |
| 9631 | <DT><B>jobs</B> <B>-x</B> <I>command</I> [ <I>args</I> ... ]<DD> |
| 9632 | |
| 9633 | The first form lists the active jobs. The options have the following |
| 9634 | meanings: |
| 9635 | <DL COMPACT><DT><DD> |
| 9636 | |
| 9637 | <DL COMPACT> |
| 9638 | <DT><B>-l</B> |
| 9639 | |
| 9640 | <DD> |
| 9641 | List process IDs |
| 9642 | in addition to the normal information. |
| 9643 | <DT><B>-p</B> |
| 9644 | |
| 9645 | <DD> |
| 9646 | List only the process ID of the job's process group |
| 9647 | leader. |
| 9648 | <DT><B>-n</B> |
| 9649 | |
| 9650 | <DD> |
| 9651 | Display information only about jobs that have changed status since |
| 9652 | the user was last notified of their status. |
| 9653 | <DT><B>-r</B> |
| 9654 | |
| 9655 | <DD> |
| 9656 | Restrict output to running jobs. |
| 9657 | <DT><B>-s</B> |
| 9658 | |
| 9659 | <DD> |
| 9660 | Restrict output to stopped jobs. |
| 9661 | |
| 9662 | </DL> |
| 9663 | <P> |
| 9664 | |
| 9665 | If |
| 9666 | <I>jobspec</I> |
| 9667 | |
| 9668 | is given, output is restricted to information about that job. |
| 9669 | The return status is 0 unless an invalid option is encountered |
| 9670 | or an invalid |
| 9671 | <I>jobspec</I> |
| 9672 | |
| 9673 | is supplied. |
| 9674 | <P> |
| 9675 | |
| 9676 | If the |
| 9677 | <B>-x</B> |
| 9678 | |
| 9679 | option is supplied, |
| 9680 | <B>jobs</B> |
| 9681 | |
| 9682 | replaces any |
| 9683 | <I>jobspec</I> |
| 9684 | |
| 9685 | found in |
| 9686 | <I>command</I> |
| 9687 | |
| 9688 | or |
| 9689 | <I>args</I> |
| 9690 | |
| 9691 | with the corresponding process group ID, and executes |
| 9692 | <I>command</I> |
| 9693 | |
| 9694 | passing it |
| 9695 | <I>args</I>, |
| 9696 | |
| 9697 | returning its exit status. |
| 9698 | </DL> |
| 9699 | |
| 9700 | <DT><B>kill</B> [<B>-s</B> <I>sigspec</I> | <B>-n</B> <I>signum</I> | <B>-</B><I>sigspec</I>] [<I>pid</I> | <I>jobspec</I>] ...<DD> |
| 9701 | |
| 9702 | <DT><B>kill</B> <B>-l</B> [<I>sigspec</I> | <I>exit_status</I>]<DD> |
| 9703 | |
| 9704 | Send the signal named by |
| 9705 | <I>sigspec</I> |
| 9706 | |
| 9707 | or |
| 9708 | <I>signum</I> |
| 9709 | |
| 9710 | to the processes named by |
| 9711 | <I>pid</I> |
| 9712 | |
| 9713 | or |
| 9714 | <I>jobspec</I>. |
| 9715 | |
| 9716 | <I>sigspec</I> |
| 9717 | |
| 9718 | is either a case-insensitive signal name such as |
| 9719 | <FONT SIZE=-1><B>SIGKILL</B> |
| 9720 | |
| 9721 | </FONT> |
| 9722 | (with or without the |
| 9723 | <FONT SIZE=-1><B>SIG</B> |
| 9724 | |
| 9725 | </FONT> |
| 9726 | prefix) or a signal number; |
| 9727 | <I>signum</I> |
| 9728 | |
| 9729 | is a signal number. |
| 9730 | If |
| 9731 | <I>sigspec</I> |
| 9732 | |
| 9733 | is not present, then |
| 9734 | <FONT SIZE=-1><B>SIGTERM</B> |
| 9735 | |
| 9736 | </FONT> |
| 9737 | is assumed. |
| 9738 | An argument of |
| 9739 | <B>-l</B> |
| 9740 | |
| 9741 | lists the signal names. |
| 9742 | If any arguments are supplied when |
| 9743 | <B>-l</B> |
| 9744 | |
| 9745 | is given, the names of the signals corresponding to the arguments are |
| 9746 | listed, and the return status is 0. |
| 9747 | The <I>exit_status</I> argument to |
| 9748 | <B>-l</B> |
| 9749 | |
| 9750 | is a number specifying either a signal number or the exit status of |
| 9751 | a process terminated by a signal. |
| 9752 | <B>kill</B> |
| 9753 | |
| 9754 | returns true if at least one signal was successfully sent, or false |
| 9755 | if an error occurs or an invalid option is encountered. |
| 9756 | <DT><B>let</B> <I>arg</I> [<I>arg</I> ...]<DD> |
| 9757 | Each |
| 9758 | <I>arg</I> |
| 9759 | |
| 9760 | is an arithmetic expression to be evaluated (see |
| 9761 | <FONT SIZE=-1><B>ARITHMETIC EVALUATION</B>). |
| 9762 | |
| 9763 | </FONT> |
| 9764 | If the last |
| 9765 | <I>arg</I> |
| 9766 | |
| 9767 | evaluates to 0, |
| 9768 | <B>let</B> |
| 9769 | |
| 9770 | returns 1; 0 is returned otherwise. |
| 9771 | <DT><B>local</B> [<I>option</I>] [<I>name</I>[=<I>value</I>] ...]<DD> |
| 9772 | For each argument, a local variable named |
| 9773 | <I>name </I> |
| 9774 | |
| 9775 | is created, and assigned |
| 9776 | <I>value</I>. |
| 9777 | |
| 9778 | The <I>option</I> can be any of the options accepted by <B>declare</B>. |
| 9779 | When |
| 9780 | <B>local</B> |
| 9781 | |
| 9782 | is used within a function, it causes the variable |
| 9783 | <I>name</I> |
| 9784 | |
| 9785 | to have a visible scope restricted to that function and its children. |
| 9786 | With no operands, |
| 9787 | <B>local</B> |
| 9788 | |
| 9789 | writes a list of local variables to the standard output. It is |
| 9790 | an error to use |
| 9791 | <B>local</B> |
| 9792 | |
| 9793 | when not within a function. The return status is 0 unless |
| 9794 | <B>local</B> |
| 9795 | |
| 9796 | is used outside a function, an invalid |
| 9797 | <I>name</I> |
| 9798 | |
| 9799 | is supplied, or |
| 9800 | <I>name</I> is a readonly variable. |
| 9801 | <DT><B>logout</B> |
| 9802 | |
| 9803 | <DD> |
| 9804 | Exit a login shell. |
| 9805 | <DT><B>mapfile</B> [<B>-n</B> <I>count</I>] [<B>-O</B> <I>origin</I>] [<B>-s</B> <I>count</I>] [<B>-t</B>] [<B>-u</B> <I>fd</I>] [<B>-C</B> <I>callback</I>] [<B>-c</B> <I>quantum</I>] [<I>array</I>]<DD> |
| 9806 | |
| 9807 | <DT><B>readarray</B> [<B>-n</B> <I>count</I>] [<B>-O</B> <I>origin</I>] [<B>-s</B> <I>count</I>] [<B>-t</B>] [<B>-u</B> <I>fd</I>] [<B>-C</B> <I>callback</I>] [<B>-c</B> <I>quantum</I>] [<I>array</I>]<DD> |
| 9808 | |
| 9809 | Read lines from the standard input into array variable |
| 9810 | <I>array</I>, |
| 9811 | |
| 9812 | or from file descriptor |
| 9813 | <I>fd</I> |
| 9814 | |
| 9815 | if the |
| 9816 | <B>-u</B> |
| 9817 | |
| 9818 | option is supplied. |
| 9819 | The variable <B>MAPFILE</B> is the default <I>array</I>. |
| 9820 | Options, if supplied, have the following meanings: |
| 9821 | <DL COMPACT><DT><DD> |
| 9822 | |
| 9823 | <DL COMPACT> |
| 9824 | <DT><B>-n</B> |
| 9825 | |
| 9826 | <DD> |
| 9827 | Copy at most |
| 9828 | <I>count</I> |
| 9829 | |
| 9830 | lines. If <I>count</I> is 0, all lines are copied. |
| 9831 | <DT><B>-O</B> |
| 9832 | |
| 9833 | <DD> |
| 9834 | Begin assigning to |
| 9835 | <I>array</I> |
| 9836 | |
| 9837 | at index |
| 9838 | <I>origin</I>. |
| 9839 | |
| 9840 | The default index is 0. |
| 9841 | <DT><B>-s</B> |
| 9842 | |
| 9843 | <DD> |
| 9844 | Discard the first <I>count</I> lines read. |
| 9845 | <DT><B>-t</B> |
| 9846 | |
| 9847 | <DD> |
| 9848 | Remove a trailing line from each line read. |
| 9849 | <DT><B>-u</B> |
| 9850 | |
| 9851 | <DD> |
| 9852 | Read lines from file descriptor <I>fd</I> instead of the standard input. |
| 9853 | <DT><B>-C</B> |
| 9854 | |
| 9855 | <DD> |
| 9856 | Evaluate |
| 9857 | <I>callback</I> |
| 9858 | |
| 9859 | each time <I>quantum</I> lines are read. The <B>-c</B> option specifies |
| 9860 | <I>quantum</I>. |
| 9861 | |
| 9862 | <DT><B>-c</B> |
| 9863 | |
| 9864 | <DD> |
| 9865 | Specify the number of lines read between each call to |
| 9866 | <I>callback</I>. |
| 9867 | |
| 9868 | |
| 9869 | </DL> |
| 9870 | <P> |
| 9871 | |
| 9872 | If |
| 9873 | <B>-C</B> |
| 9874 | |
| 9875 | is specified without |
| 9876 | <B>-c</B>, |
| 9877 | |
| 9878 | the default quantum is 5000. |
| 9879 | When <I>callback</I> is evaluated, it is supplied the index of the next |
| 9880 | array element to be assigned as an additional argument. |
| 9881 | <I>callback</I> is evaluated after the line is read but before the |
| 9882 | array element is assigned. |
| 9883 | <P> |
| 9884 | |
| 9885 | If not supplied with an explicit origin, <B>mapfile</B> will clear <I>array</I> |
| 9886 | before assigning to it. |
| 9887 | <P> |
| 9888 | |
| 9889 | <B>mapfile</B> returns successfully unless an invalid option or option |
| 9890 | argument is supplied, or <I>array</I> is invalid or unassignable. |
| 9891 | </DL> |
| 9892 | |
| 9893 | <DT><B>popd</B> [-<B>n</B>] [+<I>n</I>] [-<I>n</I>]<DD> |
| 9894 | Removes entries from the directory stack. With no arguments, |
| 9895 | removes the top directory from the stack, and performs a |
| 9896 | <B>cd</B> |
| 9897 | |
| 9898 | to the new top directory. |
| 9899 | Arguments, if supplied, have the following meanings: |
| 9900 | <DL COMPACT><DT><DD> |
| 9901 | |
| 9902 | <DL COMPACT> |
| 9903 | <DT><B>-n</B> |
| 9904 | |
| 9905 | <DD> |
| 9906 | Suppresses the normal change of directory when removing directories |
| 9907 | from the stack, so that only the stack is manipulated. |
| 9908 | <DT><B>+</B><I>n</I><DD> |
| 9909 | Removes the <I>n</I>th entry counting from the left of the list |
| 9910 | shown by |
| 9911 | <B>dirs</B>, |
| 9912 | |
| 9913 | starting with zero. For example: |
| 9914 | |
| 9915 | <TT>popd +0</TT> |
| 9916 | removes the first directory, |
| 9917 | |
| 9918 | <TT>popd +1</TT> |
| 9919 | the second. |
| 9920 | <DT><B>-</B><I>n</I><DD> |
| 9921 | Removes the <I>n</I>th entry counting from the right of the list |
| 9922 | shown by |
| 9923 | <B>dirs</B>, |
| 9924 | |
| 9925 | starting with zero. For example: |
| 9926 | |
| 9927 | <TT>popd -0</TT> |
| 9928 | removes the last directory, |
| 9929 | |
| 9930 | <TT>popd -1</TT> |
| 9931 | the next to last. |
| 9932 | |
| 9933 | </DL> |
| 9934 | <P> |
| 9935 | |
| 9936 | If the |
| 9937 | <B>popd</B> |
| 9938 | |
| 9939 | command is successful, a |
| 9940 | <B>dirs</B> |
| 9941 | |
| 9942 | is performed as well, and the return status is 0. |
| 9943 | <B>popd</B> |
| 9944 | |
| 9945 | returns false if an invalid option is encountered, the directory stack |
| 9946 | is empty, a non-existent directory stack entry is specified, or the |
| 9947 | directory change fails. |
| 9948 | </DL> |
| 9949 | |
| 9950 | <DT><B>printf</B> [<B>-v</B> <I>var</I>] <I>format</I> [<I>arguments</I>]<DD> |
| 9951 | Write the formatted <I>arguments</I> to the standard output under the |
| 9952 | control of the <I>format</I>. |
| 9953 | The <I>format</I> is a character string which contains three types of objects: |
| 9954 | plain characters, which are simply copied to standard output, character |
| 9955 | escape sequences, which are converted and copied to the standard output, and |
| 9956 | format specifications, each of which causes printing of the next successive |
| 9957 | <I>argument</I>. |
| 9958 | In addition to the standard <I>printf</I>(1) formats, <B>%b</B> causes |
| 9959 | <B>printf</B> to expand backslash escape sequences in the corresponding |
| 9960 | <I>argument</I> (except that <B>\c</B> terminates output, backslashes in |
| 9961 | <B>\aq</B>, <B>\"</B>, and <B>\?</B> are not removed, and octal escapes |
| 9962 | beginning with <B>\0</B> may contain up to four digits), |
| 9963 | and <B>%q</B> causes <B>printf</B> to output the corresponding |
| 9964 | <I>argument</I> in a format that can be reused as shell input. |
| 9965 | <P> |
| 9966 | The <B>-v</B> option causes the output to be assigned to the variable |
| 9967 | <I>var</I> rather than being printed to the standard output. |
| 9968 | <P> |
| 9969 | The <I>format</I> is reused as necessary to consume all of the <I>arguments</I>. |
| 9970 | If the <I>format</I> requires more <I>arguments</I> than are supplied, the |
| 9971 | extra format specifications behave as if a zero value or null string, as |
| 9972 | appropriate, had been supplied. The return value is zero on success, |
| 9973 | non-zero on failure. |
| 9974 | <DT><B>pushd</B> [<B>-n</B>] [+<I>n</I>] [-<I>n</I>]<DD> |
| 9975 | |
| 9976 | <DT><B>pushd</B> [<B>-n</B>] [<I>dir</I>]<DD> |
| 9977 | |
| 9978 | Adds a directory to the top of the directory stack, or rotates |
| 9979 | the stack, making the new top of the stack the current working |
| 9980 | directory. With no arguments, exchanges the top two directories |
| 9981 | and returns 0, unless the directory stack is empty. |
| 9982 | Arguments, if supplied, have the following meanings: |
| 9983 | <DL COMPACT><DT><DD> |
| 9984 | |
| 9985 | <DL COMPACT> |
| 9986 | <DT><B>-n</B> |
| 9987 | |
| 9988 | <DD> |
| 9989 | Suppresses the normal change of directory when adding directories |
| 9990 | to the stack, so that only the stack is manipulated. |
| 9991 | <DT><B>+</B><I>n</I><DD> |
| 9992 | Rotates the stack so that the <I>n</I>th directory |
| 9993 | (counting from the left of the list shown by |
| 9994 | <B>dirs</B>, |
| 9995 | |
| 9996 | starting with zero) |
| 9997 | is at the top. |
| 9998 | <DT><B>-</B><I>n</I><DD> |
| 9999 | Rotates the stack so that the <I>n</I>th directory |
| 10000 | (counting from the right of the list shown by |
| 10001 | <B>dirs</B>, |
| 10002 | |
| 10003 | starting with zero) is at the top. |
| 10004 | <DT><I>dir</I> |
| 10005 | |
| 10006 | <DD> |
| 10007 | Adds |
| 10008 | <I>dir</I> |
| 10009 | |
| 10010 | to the directory stack at the top, making it the |
| 10011 | new current working directory. |
| 10012 | |
| 10013 | </DL> |
| 10014 | <P> |
| 10015 | |
| 10016 | If the |
| 10017 | <B>pushd</B> |
| 10018 | |
| 10019 | command is successful, a |
| 10020 | <B>dirs</B> |
| 10021 | |
| 10022 | is performed as well. |
| 10023 | If the first form is used, |
| 10024 | <B>pushd</B> |
| 10025 | |
| 10026 | returns 0 unless the cd to |
| 10027 | <I>dir</I> |
| 10028 | |
| 10029 | fails. With the second form, |
| 10030 | <B>pushd</B> |
| 10031 | |
| 10032 | returns 0 unless the directory stack is empty, |
| 10033 | a non-existent directory stack element is specified, |
| 10034 | or the directory change to the specified new current directory |
| 10035 | fails. |
| 10036 | </DL> |
| 10037 | |
| 10038 | <DT><B>pwd</B> [<B>-LP</B>]<DD> |
| 10039 | Print the absolute pathname of the current working directory. |
| 10040 | The pathname printed contains no symbolic links if the |
| 10041 | <B>-P</B> |
| 10042 | |
| 10043 | option is supplied or the |
| 10044 | <B>-o physical</B> |
| 10045 | |
| 10046 | option to the |
| 10047 | <B>set</B> |
| 10048 | |
| 10049 | builtin command is enabled. |
| 10050 | If the |
| 10051 | <B>-L</B> |
| 10052 | |
| 10053 | option is used, the pathname printed may contain symbolic links. |
| 10054 | The return status is 0 unless an error occurs while |
| 10055 | reading the name of the current directory or an |
| 10056 | invalid option is supplied. |
| 10057 | <DT><B>read</B> [<B>-ers</B>] [<B>-a</B> <I>aname</I>] [<B>-d</B> <I>delim</I>] [<B>-</B> <I>text</I>] [<B>-n</B> <I>nchars</I>] [<B>-p</B> <I>prompt</I>] [<B>-t</B> <I>timeout</I>] [<B>-u</B> <I>fd</I>] [<I>name</I> ...]<DD> |
| 10058 | One line is read from the standard input, or from the file descriptor |
| 10059 | <I>fd</I> supplied as an argument to the <B>-u</B> option, and the first word |
| 10060 | is assigned to the first |
| 10061 | <I>name</I>, |
| 10062 | |
| 10063 | the second word to the second |
| 10064 | <I>name</I>, |
| 10065 | |
| 10066 | and so on, with leftover words and their intervening separators assigned |
| 10067 | to the last |
| 10068 | <I>name</I>. |
| 10069 | |
| 10070 | If there are fewer words read from the input stream than names, |
| 10071 | the remaining names are assigned empty values. |
| 10072 | The characters in |
| 10073 | <FONT SIZE=-1><B>IFS</B> |
| 10074 | |
| 10075 | </FONT> |
| 10076 | are used to split the line into words. |
| 10077 | The backslash character (<B>\</B>) may be used to remove any special |
| 10078 | meaning for the next character read and for line continuation. |
| 10079 | Options, if supplied, have the following meanings: |
| 10080 | <DL COMPACT><DT><DD> |
| 10081 | |
| 10082 | <DL COMPACT> |
| 10083 | <DT><B>-a </B><I>aname</I> |
| 10084 | |
| 10085 | <DD> |
| 10086 | The words are assigned to sequential indices |
| 10087 | of the array variable |
| 10088 | <I>aname</I>, |
| 10089 | |
| 10090 | starting at 0. |
| 10091 | <I>aname</I> |
| 10092 | |
| 10093 | is unset before any new values are assigned. |
| 10094 | Other <I>name</I> arguments are ignored. |
| 10095 | <DT><B>-d </B><I>delim</I> |
| 10096 | |
| 10097 | <DD> |
| 10098 | The first character of <I>delim</I> is used to terminate the input line, |
| 10099 | rather than newline. |
| 10100 | <DT><B>-e</B> |
| 10101 | |
| 10102 | <DD> |
| 10103 | If the standard input |
| 10104 | is coming from a terminal, |
| 10105 | <B>readline</B> |
| 10106 | |
| 10107 | (see |
| 10108 | <FONT SIZE=-1><B>READLINE</B> |
| 10109 | |
| 10110 | </FONT> |
| 10111 | above) is used to obtain the line. |
| 10112 | Readline uses the current (or default, if line editing was not previously |
| 10113 | active) editing settings. |
| 10114 | <DT><B>-i </B><I>text</I> |
| 10115 | |
| 10116 | <DD> |
| 10117 | If |
| 10118 | <B>readline</B> |
| 10119 | |
| 10120 | is being used to read the line, <I>text</I> is placed into the editing |
| 10121 | buffer before editing begins. |
| 10122 | <DT><B>-n </B><I>nchars</I> |
| 10123 | |
| 10124 | <DD> |
| 10125 | <B>read</B> returns after reading <I>nchars</I> characters rather than |
| 10126 | waiting for a complete line of input. |
| 10127 | <DT><B>-p </B><I>prompt</I> |
| 10128 | |
| 10129 | <DD> |
| 10130 | Display <I>prompt</I> on standard error, without a |
| 10131 | trailing newline, before attempting to read any input. The prompt |
| 10132 | is displayed only if input is coming from a terminal. |
| 10133 | <DT><B>-r</B> |
| 10134 | |
| 10135 | <DD> |
| 10136 | Backslash does not act as an escape character. |
| 10137 | The backslash is considered to be part of the line. |
| 10138 | In particular, a backslash-newline pair may not be used as a line |
| 10139 | continuation. |
| 10140 | <DT><B>-s</B> |
| 10141 | |
| 10142 | <DD> |
| 10143 | Silent mode. If input is coming from a terminal, characters are |
| 10144 | not echoed. |
| 10145 | <DT><B>-t </B><I>timeout</I> |
| 10146 | |
| 10147 | <DD> |
| 10148 | Cause <B>read</B> to time out and return failure if a complete line of |
| 10149 | input is not read within <I>timeout</I> seconds. |
| 10150 | <I>timeout</I> may be a decimal number with a fractional portion following |
| 10151 | the decimal point. |
| 10152 | This option is only effective if <B>read</B> is reading input from a |
| 10153 | terminal, pipe, or other special file; it has no effect when reading |
| 10154 | from regular files. |
| 10155 | If <I>timeout</I> is 0, <B>read</B> returns success if input is available on |
| 10156 | the specified file descriptor, failure otherwise. |
| 10157 | The exit status is greater than 128 if the timeout is exceeded. |
| 10158 | <DT><B>-u </B><I>fd</I> |
| 10159 | |
| 10160 | <DD> |
| 10161 | Read input from file descriptor <I>fd</I>. |
| 10162 | |
| 10163 | </DL> |
| 10164 | <P> |
| 10165 | |
| 10166 | If no |
| 10167 | <I>names</I> |
| 10168 | |
| 10169 | are supplied, the line read is assigned to the variable |
| 10170 | <FONT SIZE=-1><B>REPLY</B>. |
| 10171 | |
| 10172 | </FONT> |
| 10173 | The return code is zero, unless end-of-file is encountered, <B>read</B> |
| 10174 | times out (in which case the return code is greater than 128), or an |
| 10175 | invalid file descriptor is supplied as the argument to <B>-u</B>. |
| 10176 | </DL> |
| 10177 | |
| 10178 | <DT><B>readonly</B> [<B>-aApf</B>] [<I>name</I>[=<I>word</I>] ...]<DD> |
| 10179 | |
| 10180 | The given |
| 10181 | <I>names</I> are marked readonly; the values of these |
| 10182 | <I>names</I> |
| 10183 | |
| 10184 | may not be changed by subsequent assignment. |
| 10185 | If the |
| 10186 | <B>-f</B> |
| 10187 | |
| 10188 | option is supplied, the functions corresponding to the |
| 10189 | <I>names</I> are so |
| 10190 | marked. |
| 10191 | The |
| 10192 | <B>-a</B> |
| 10193 | |
| 10194 | option restricts the variables to indexed arrays; the |
| 10195 | <B>-A</B> |
| 10196 | |
| 10197 | option restricts the variables to associative arrays. |
| 10198 | If no |
| 10199 | <I>name</I> |
| 10200 | |
| 10201 | arguments are given, or if the |
| 10202 | <B>-p</B> |
| 10203 | |
| 10204 | option is supplied, a list of all readonly names is printed. |
| 10205 | The |
| 10206 | <B>-p</B> |
| 10207 | |
| 10208 | option causes output to be displayed in a format that |
| 10209 | may be reused as input. |
| 10210 | If a variable name is followed by =<I>word</I>, the value of |
| 10211 | the variable is set to <I>word</I>. |
| 10212 | The return status is 0 unless an invalid option is encountered, |
| 10213 | one of the |
| 10214 | <I>names</I> |
| 10215 | |
| 10216 | is not a valid shell variable name, or |
| 10217 | <B>-f</B> |
| 10218 | |
| 10219 | is supplied with a |
| 10220 | <I>name</I> |
| 10221 | |
| 10222 | that is not a function. |
| 10223 | <DT><B>return</B> [<I>n</I>]<DD> |
| 10224 | Causes a function to exit with the return value specified by |
| 10225 | <I>n</I>. |
| 10226 | |
| 10227 | If |
| 10228 | <I>n</I> |
| 10229 | |
| 10230 | is omitted, the return status is that of the last command |
| 10231 | executed in the function body. If used outside a function, |
| 10232 | but during execution of a script by the |
| 10233 | <B>.</B> |
| 10234 | |
| 10235 | (<B>source</B>) command, it causes the shell to stop executing |
| 10236 | that script and return either |
| 10237 | <I>n</I> |
| 10238 | |
| 10239 | or the exit status of the last command executed within the |
| 10240 | script as the exit status of the script. If used outside a |
| 10241 | function and not during execution of a script by <B>.</B>, |
| 10242 | the return status is false. |
| 10243 | Any command associated with the <B>RETURN</B> trap is executed |
| 10244 | before execution resumes after the function or script. |
| 10245 | <DT><B>set</B> [<B>--abefhkmnptuvxBCEHPT</B>] [<B>-o</B> <I>option</I>] [<I>arg</I> ...]<DD> |
| 10246 | |
| 10247 | <DT><B>set</B> [<B>+abefhkmnptuvxBCEHPT</B>] [<B>+o</B> <I>option</I>] [<I>arg</I> ...]<DD> |
| 10248 | |
| 10249 | Without options, the name and value of each shell variable are displayed |
| 10250 | in a format that can be reused as input |
| 10251 | for setting or resetting the currently-set variables. |
| 10252 | Read-only variables cannot be reset. |
| 10253 | In <I>posix mode</I>, only shell variables are listed. |
| 10254 | The output is sorted according to the current locale. |
| 10255 | When options are specified, they set or unset shell attributes. |
| 10256 | Any arguments remaining after option processing are treated |
| 10257 | as values for the positional parameters and are assigned, in order, to |
| 10258 | <B>$1</B>, |
| 10259 | |
| 10260 | <B>$2</B>, |
| 10261 | |
| 10262 | <B>...</B> |
| 10263 | |
| 10264 | <B>$</B><I>n</I>. |
| 10265 | |
| 10266 | Options, if specified, have the following meanings: |
| 10267 | <DL COMPACT><DT><DD> |
| 10268 | |
| 10269 | <DL COMPACT> |
| 10270 | <DT><B>-a</B> |
| 10271 | |
| 10272 | <DD> |
| 10273 | Automatically mark variables and functions which are modified or |
| 10274 | created for export to the environment of subsequent commands. |
| 10275 | <DT><B>-b</B> |
| 10276 | |
| 10277 | <DD> |
| 10278 | Report the status of terminated background jobs |
| 10279 | immediately, rather than before the next primary prompt. This is |
| 10280 | effective only when job control is enabled. |
| 10281 | <DT><B>-e</B> |
| 10282 | |
| 10283 | <DD> |
| 10284 | Exit immediately if a <I>simple command</I> (see |
| 10285 | <FONT SIZE=-1><B>SHELL GRAMMAR</B> |
| 10286 | |
| 10287 | </FONT> |
| 10288 | above) exits with a non-zero status. |
| 10289 | The shell does not exit if the |
| 10290 | command that fails is part of the command list immediately following a |
| 10291 | <B>while</B> |
| 10292 | |
| 10293 | or |
| 10294 | <B>until</B> |
| 10295 | |
| 10296 | keyword, |
| 10297 | part of the test in an |
| 10298 | <B>if</B> |
| 10299 | |
| 10300 | statement, part of a command executed in a |
| 10301 | <B>&&</B> |
| 10302 | |
| 10303 | or |
| 10304 | <B>||</B> |
| 10305 | |
| 10306 | list, |
| 10307 | any command in a pipeline but the last, |
| 10308 | or if the command's return value is |
| 10309 | being inverted via |
| 10310 | <B>!</B>. |
| 10311 | |
| 10312 | Failing simple commands that are part of shell functions or command lists |
| 10313 | enclosed in braces or parentheses satisfying the above conditions do not |
| 10314 | cause the shell to exit. |
| 10315 | A trap on <B>ERR</B>, if set, is executed before the shell exits. |
| 10316 | <DT><B>-f</B> |
| 10317 | |
| 10318 | <DD> |
| 10319 | Disable pathname expansion. |
| 10320 | <DT><B>-h</B> |
| 10321 | |
| 10322 | <DD> |
| 10323 | Remember the location of commands as they are looked up for execution. |
| 10324 | This is enabled by default. |
| 10325 | <DT><B>-k</B> |
| 10326 | |
| 10327 | <DD> |
| 10328 | All arguments in the form of assignment statements |
| 10329 | are placed in the environment for a command, not just |
| 10330 | those that precede the command name. |
| 10331 | <DT><B>-m</B> |
| 10332 | |
| 10333 | <DD> |
| 10334 | Monitor mode. Job control is enabled. This option is on |
| 10335 | by default for interactive shells on systems that support |
| 10336 | it (see |
| 10337 | <FONT SIZE=-1><B>JOB CONTROL</B> |
| 10338 | |
| 10339 | </FONT> |
| 10340 | above). Background processes run in a separate process |
| 10341 | group and a line containing their exit status is printed |
| 10342 | upon their completion. |
| 10343 | <DT><B>-n</B> |
| 10344 | |
| 10345 | <DD> |
| 10346 | Read commands but do not execute them. This may be used to |
| 10347 | check a shell script for syntax errors. This is ignored by |
| 10348 | interactive shells. |
| 10349 | <DT><B>-o </B><I>option-name</I> |
| 10350 | |
| 10351 | <DD> |
| 10352 | The <I>option-name</I> can be one of the following: |
| 10353 | <DL COMPACT><DT><DD> |
| 10354 | <DL COMPACT> |
| 10355 | <DT><B>allexport</B> |
| 10356 | |
| 10357 | <DD> |
| 10358 | Same as |
| 10359 | <B>-a</B>. |
| 10360 | |
| 10361 | <DT><B>braceexpand</B> |
| 10362 | |
| 10363 | <DD> |
| 10364 | Same as |
| 10365 | <B>-B</B>. |
| 10366 | |
| 10367 | <DT><B>emacs</B> |
| 10368 | |
| 10369 | <DD> |
| 10370 | Use an emacs-style command line editing interface. This is enabled |
| 10371 | by default when the shell is interactive, unless the shell is started |
| 10372 | with the |
| 10373 | <B>--noediting</B> |
| 10374 | |
| 10375 | option. |
| 10376 | This also affects the editing interface used for <B>read -e</B>. |
| 10377 | <DT><B>errtrace</B> |
| 10378 | |
| 10379 | <DD> |
| 10380 | Same as |
| 10381 | <B>-E</B>. |
| 10382 | |
| 10383 | <DT><B>functrace</B> |
| 10384 | |
| 10385 | <DD> |
| 10386 | Same as |
| 10387 | <B>-T</B>. |
| 10388 | |
| 10389 | <DT><B>errexit</B> |
| 10390 | |
| 10391 | <DD> |
| 10392 | Same as |
| 10393 | <B>-e</B>. |
| 10394 | |
| 10395 | <DT><B>hashall</B> |
| 10396 | |
| 10397 | <DD> |
| 10398 | Same as |
| 10399 | <B>-h</B>. |
| 10400 | |
| 10401 | <DT><B>histexpand</B> |
| 10402 | |
| 10403 | <DD> |
| 10404 | Same as |
| 10405 | <B>-H</B>. |
| 10406 | |
| 10407 | <DT><B>history</B> |
| 10408 | |
| 10409 | <DD> |
| 10410 | Enable command history, as described above under |
| 10411 | <FONT SIZE=-1><B>HISTORY</B>. |
| 10412 | |
| 10413 | </FONT> |
| 10414 | This option is on by default in interactive shells. |
| 10415 | <DT><B>ignoreeof</B> |
| 10416 | |
| 10417 | <DD> |
| 10418 | The effect is as if the shell command |
| 10419 | <TT>IGNOREEOF=10</TT> |
| 10420 | |
| 10421 | had been executed |
| 10422 | (see |
| 10423 | <B>Shell Variables</B> |
| 10424 | |
| 10425 | above). |
| 10426 | <DT><B>keyword</B> |
| 10427 | |
| 10428 | <DD> |
| 10429 | Same as |
| 10430 | <B>-k</B>. |
| 10431 | |
| 10432 | <DT><B>monitor</B> |
| 10433 | |
| 10434 | <DD> |
| 10435 | Same as |
| 10436 | <B>-m</B>. |
| 10437 | |
| 10438 | <DT><B>noclobber</B> |
| 10439 | |
| 10440 | <DD> |
| 10441 | Same as |
| 10442 | <B>-C</B>. |
| 10443 | |
| 10444 | <DT><B>noexec</B> |
| 10445 | |
| 10446 | <DD> |
| 10447 | Same as |
| 10448 | <B>-n</B>. |
| 10449 | |
| 10450 | <DT><B>noglob</B> |
| 10451 | |
| 10452 | <DD> |
| 10453 | Same as |
| 10454 | <B>-f</B>. |
| 10455 | |
| 10456 | <DT><B>nolog</B> |
| 10457 | |
| 10458 | <DD> |
| 10459 | Currently ignored. |
| 10460 | <DT><B>notify</B> |
| 10461 | |
| 10462 | <DD> |
| 10463 | Same as |
| 10464 | <B>-b</B>. |
| 10465 | |
| 10466 | <DT><B>nounset</B> |
| 10467 | |
| 10468 | <DD> |
| 10469 | Same as |
| 10470 | <B>-u</B>. |
| 10471 | |
| 10472 | <DT><B>onecmd</B> |
| 10473 | |
| 10474 | <DD> |
| 10475 | Same as |
| 10476 | <B>-t</B>. |
| 10477 | |
| 10478 | <DT><B>physical</B> |
| 10479 | |
| 10480 | <DD> |
| 10481 | Same as |
| 10482 | <B>-P</B>. |
| 10483 | |
| 10484 | <DT><B>pipefail</B> |
| 10485 | |
| 10486 | <DD> |
| 10487 | If set, the return value of a pipeline is the value of the last |
| 10488 | (rightmost) command to exit with a non-zero status, or zero if all |
| 10489 | commands in the pipeline exit successfully. |
| 10490 | This option is disabled by default. |
| 10491 | <DT><B>posix</B> |
| 10492 | |
| 10493 | <DD> |
| 10494 | Change the behavior of |
| 10495 | <B>bash</B> |
| 10496 | |
| 10497 | where the default operation differs |
| 10498 | from the POSIX standard to match the standard (<I>posix mode</I>). |
| 10499 | <DT><B>privileged</B> |
| 10500 | |
| 10501 | <DD> |
| 10502 | Same as |
| 10503 | <B>-p</B>. |
| 10504 | |
| 10505 | <DT><B>verbose</B> |
| 10506 | |
| 10507 | <DD> |
| 10508 | Same as |
| 10509 | <B>-v</B>. |
| 10510 | |
| 10511 | <DT><B>vi</B> |
| 10512 | |
| 10513 | <DD> |
| 10514 | Use a vi-style command line editing interface. |
| 10515 | This also affects the editing interface used for <B>read -e</B>. |
| 10516 | <DT><B>xtrace</B> |
| 10517 | |
| 10518 | <DD> |
| 10519 | Same as |
| 10520 | <B>-x</B>. |
| 10521 | |
| 10522 | <P> |
| 10523 | </DL> |
| 10524 | <P> |
| 10525 | |
| 10526 | If |
| 10527 | <B>-o</B> |
| 10528 | |
| 10529 | is supplied with no <I>option-name</I>, the values of the current options are |
| 10530 | printed. |
| 10531 | If |
| 10532 | <B>+o</B> |
| 10533 | |
| 10534 | is supplied with no <I>option-name</I>, a series of |
| 10535 | <B>set</B> |
| 10536 | |
| 10537 | commands to recreate the current option settings is displayed on |
| 10538 | the standard output. |
| 10539 | </DL> |
| 10540 | |
| 10541 | <DT><B>-p</B> |
| 10542 | |
| 10543 | <DD> |
| 10544 | Turn on |
| 10545 | <I>privileged</I> |
| 10546 | |
| 10547 | mode. In this mode, the |
| 10548 | <FONT SIZE=-1><B>$ENV</B> |
| 10549 | |
| 10550 | </FONT> |
| 10551 | and |
| 10552 | <FONT SIZE=-1><B>$BASH_ENV</B> |
| 10553 | |
| 10554 | </FONT> |
| 10555 | files are not processed, shell functions are not inherited from the |
| 10556 | environment, and the |
| 10557 | <FONT SIZE=-1><B>SHELLOPTS</B>, |
| 10558 | |
| 10559 | </FONT> |
| 10560 | <B>CDPATH</B>, |
| 10561 | |
| 10562 | and |
| 10563 | <B>GLOBIGNORE</B> |
| 10564 | |
| 10565 | variables, if they appear in the environment, are ignored. |
| 10566 | If the shell is started with the effective user (group) id not equal to the |
| 10567 | real user (group) id, and the <B>-p</B> option is not supplied, these actions |
| 10568 | are taken and the effective user id is set to the real user id. |
| 10569 | If the <B>-p</B> option is supplied at startup, the effective user id is |
| 10570 | not reset. |
| 10571 | Turning this option off causes the effective user |
| 10572 | and group ids to be set to the real user and group ids. |
| 10573 | <DT><B>-t</B> |
| 10574 | |
| 10575 | <DD> |
| 10576 | Exit after reading and executing one command. |
| 10577 | <DT><B>-u</B> |
| 10578 | |
| 10579 | <DD> |
| 10580 | Treat unset variables as an error when performing |
| 10581 | parameter expansion. If expansion is attempted on an |
| 10582 | unset variable, the shell prints an error message, and, |
| 10583 | if not interactive, exits with a non-zero status. |
| 10584 | <DT><B>-v</B> |
| 10585 | |
| 10586 | <DD> |
| 10587 | Print shell input lines as they are read. |
| 10588 | <DT><B>-x</B> |
| 10589 | |
| 10590 | <DD> |
| 10591 | After expanding each <I>simple command</I>, |
| 10592 | <B>for</B> command, <B>case</B> command, <B>select</B> command, or |
| 10593 | arithmetic <B>for</B> command, display the expanded value of |
| 10594 | <FONT SIZE=-1><B>PS4</B>, |
| 10595 | |
| 10596 | </FONT> |
| 10597 | followed by the command and its expanded arguments |
| 10598 | or associated word list. |
| 10599 | <DT><B>-B</B> |
| 10600 | |
| 10601 | <DD> |
| 10602 | The shell performs brace expansion (see |
| 10603 | <B>Brace Expansion</B> |
| 10604 | |
| 10605 | above). This is on by default. |
| 10606 | <DT><B>-C</B> |
| 10607 | |
| 10608 | <DD> |
| 10609 | If set, |
| 10610 | <B>bash</B> |
| 10611 | |
| 10612 | does not overwrite an existing file with the |
| 10613 | <B>></B>, |
| 10614 | |
| 10615 | <B>>&</B>, |
| 10616 | |
| 10617 | and |
| 10618 | <B><></B> |
| 10619 | |
| 10620 | redirection operators. This may be overridden when |
| 10621 | creating output files by using the redirection operator |
| 10622 | <B>>|</B> |
| 10623 | |
| 10624 | instead of |
| 10625 | <B>></B>. |
| 10626 | |
| 10627 | <DT><B>-E</B> |
| 10628 | |
| 10629 | <DD> |
| 10630 | If set, any trap on <B>ERR</B> is inherited by shell functions, command |
| 10631 | substitutions, and commands executed in a subshell environment. |
| 10632 | The <B>ERR</B> trap is normally not inherited in such cases. |
| 10633 | <DT><B>-H</B> |
| 10634 | |
| 10635 | <DD> |
| 10636 | Enable |
| 10637 | <B>!</B> |
| 10638 | |
| 10639 | style history substitution. This option is on by |
| 10640 | default when the shell is interactive. |
| 10641 | <DT><B>-P</B> |
| 10642 | |
| 10643 | <DD> |
| 10644 | If set, the shell does not follow symbolic links when executing |
| 10645 | commands such as |
| 10646 | <B>cd</B> |
| 10647 | |
| 10648 | that change the current working directory. It uses the |
| 10649 | physical directory structure instead. By default, |
| 10650 | <B>bash</B> |
| 10651 | |
| 10652 | follows the logical chain of directories when performing commands |
| 10653 | which change the current directory. |
| 10654 | <DT><B>-T</B> |
| 10655 | |
| 10656 | <DD> |
| 10657 | If set, any traps on <B>DEBUG</B> and <B>RETURN</B> are inherited by shell |
| 10658 | functions, command substitutions, and commands executed in a |
| 10659 | subshell environment. |
| 10660 | The <B>DEBUG</B> and <B>RETURN</B> traps are normally not inherited |
| 10661 | in such cases. |
| 10662 | <DT><B>--</B> |
| 10663 | |
| 10664 | <DD> |
| 10665 | If no arguments follow this option, then the positional parameters are |
| 10666 | unset. Otherwise, the positional parameters are set to the |
| 10667 | <I>arg</I>s, even if some of them begin with a |
| 10668 | <B>-</B>. |
| 10669 | |
| 10670 | <DT><B>-</B> |
| 10671 | |
| 10672 | <DD> |
| 10673 | Signal the end of options, cause all remaining <I>arg</I>s to be |
| 10674 | assigned to the positional parameters. The |
| 10675 | <B>-x</B> |
| 10676 | |
| 10677 | and |
| 10678 | <B>-v</B> |
| 10679 | |
| 10680 | options are turned off. |
| 10681 | If there are no <I>arg</I>s, |
| 10682 | the positional parameters remain unchanged. |
| 10683 | |
| 10684 | </DL> |
| 10685 | <P> |
| 10686 | |
| 10687 | The options are off by default unless otherwise noted. |
| 10688 | Using + rather than - causes these options to be turned off. |
| 10689 | The options can also be specified as arguments to an invocation of |
| 10690 | the shell. |
| 10691 | The current set of options may be found in |
| 10692 | <B>$-</B>. |
| 10693 | |
| 10694 | The return status is always true unless an invalid option is encountered. |
| 10695 | </DL> |
| 10696 | |
| 10697 | <DT><B>shift</B> [<I>n</I>]<DD> |
| 10698 | The positional parameters from <I>n</I>+1 ... are renamed to |
| 10699 | <B>$1</B> |
| 10700 | |
| 10701 | <B>....</B> |
| 10702 | |
| 10703 | Parameters represented by the numbers <B>$#</B> |
| 10704 | down to <B>$#</B>-<I>n</I>+1 are unset. |
| 10705 | <I>n</I> |
| 10706 | |
| 10707 | must be a non-negative number less than or equal to <B>$#</B>. |
| 10708 | If |
| 10709 | <I>n</I> |
| 10710 | |
| 10711 | is 0, no parameters are changed. |
| 10712 | If |
| 10713 | <I>n </I> |
| 10714 | |
| 10715 | is not given, it is assumed to be 1. |
| 10716 | If |
| 10717 | <I>n</I> |
| 10718 | |
| 10719 | is greater than <B>$#</B>, the positional parameters are not changed. |
| 10720 | The return status is greater than zero if |
| 10721 | <I>n</I> |
| 10722 | |
| 10723 | is greater than |
| 10724 | <B>$#</B> |
| 10725 | |
| 10726 | or less than zero; otherwise 0. |
| 10727 | <DT><B>shopt</B> [<B>-pqsu</B>] [<B>-o</B>] [<I>optname</I> ...]<DD> |
| 10728 | Toggle the values of variables controlling optional shell behavior. |
| 10729 | With no options, or with the |
| 10730 | <B>-p</B> |
| 10731 | |
| 10732 | option, a list of all settable options is displayed, with |
| 10733 | an indication of whether or not each is set. |
| 10734 | The <B>-p</B> option causes output to be displayed in a form that |
| 10735 | may be reused as input. |
| 10736 | Other options have the following meanings: |
| 10737 | <DL COMPACT><DT><DD> |
| 10738 | |
| 10739 | <DL COMPACT> |
| 10740 | <DT><B>-s</B> |
| 10741 | |
| 10742 | <DD> |
| 10743 | Enable (set) each <I>optname</I>. |
| 10744 | <DT><B>-u</B> |
| 10745 | |
| 10746 | <DD> |
| 10747 | Disable (unset) each <I>optname</I>. |
| 10748 | <DT><B>-q</B> |
| 10749 | |
| 10750 | <DD> |
| 10751 | Suppresses normal output (quiet mode); the return status indicates |
| 10752 | whether the <I>optname</I> is set or unset. |
| 10753 | If multiple <I>optname</I> arguments are given with |
| 10754 | <B>-q</B>, |
| 10755 | |
| 10756 | the return status is zero if all <I>optnames</I> are enabled; non-zero |
| 10757 | otherwise. |
| 10758 | <DT><B>-o</B> |
| 10759 | |
| 10760 | <DD> |
| 10761 | Restricts the values of <I>optname</I> to be those defined for the |
| 10762 | <B>-o</B> |
| 10763 | |
| 10764 | option to the |
| 10765 | <B>set</B> |
| 10766 | |
| 10767 | builtin. |
| 10768 | |
| 10769 | </DL> |
| 10770 | <P> |
| 10771 | |
| 10772 | If either |
| 10773 | <B>-s</B> |
| 10774 | |
| 10775 | or |
| 10776 | <B>-u</B> |
| 10777 | |
| 10778 | is used with no <I>optname</I> arguments, the display is limited to |
| 10779 | those options which are set or unset, respectively. |
| 10780 | Unless otherwise noted, the <B>shopt</B> options are disabled (unset) |
| 10781 | by default. |
| 10782 | <P> |
| 10783 | |
| 10784 | The return status when listing options is zero if all <I>optnames</I> |
| 10785 | are enabled, non-zero otherwise. When setting or unsetting options, |
| 10786 | the return status is zero unless an <I>optname</I> is not a valid shell |
| 10787 | option. |
| 10788 | <P> |
| 10789 | |
| 10790 | The list of <B>shopt</B> options is: |
| 10791 | <P> |
| 10792 | |
| 10793 | |
| 10794 | |
| 10795 | <DL COMPACT> |
| 10796 | <DT><B>autocd</B> |
| 10797 | |
| 10798 | <DD> |
| 10799 | If set, a command name that is the name of a directory is executed as if |
| 10800 | it were the argument to the <B>cd</B> command. |
| 10801 | This option is only used by interactive shells. |
| 10802 | <DT><B>cdable_vars</B> |
| 10803 | |
| 10804 | <DD> |
| 10805 | If set, an argument to the |
| 10806 | <B>cd</B> |
| 10807 | |
| 10808 | builtin command that |
| 10809 | is not a directory is assumed to be the name of a variable whose |
| 10810 | value is the directory to change to. |
| 10811 | <DT><B>cdspell</B> |
| 10812 | |
| 10813 | <DD> |
| 10814 | If set, minor errors in the spelling of a directory component in a |
| 10815 | <B>cd</B> |
| 10816 | |
| 10817 | command will be corrected. |
| 10818 | The errors checked for are transposed characters, |
| 10819 | a missing character, and one character too many. |
| 10820 | If a correction is found, the corrected file name is printed, |
| 10821 | and the command proceeds. |
| 10822 | This option is only used by interactive shells. |
| 10823 | <DT><B>checkhash</B> |
| 10824 | |
| 10825 | <DD> |
| 10826 | If set, <B>bash</B> checks that a command found in the hash |
| 10827 | table exists before trying to execute it. If a hashed command no |
| 10828 | longer exists, a normal path search is performed. |
| 10829 | <DT><B>checkjobs</B> |
| 10830 | |
| 10831 | <DD> |
| 10832 | If set, <B>bash</B> lists the status of any stopped and running jobs before |
| 10833 | exiting an interactive shell. If any jobs are running, this causes |
| 10834 | the exit to be deferred until a second exit is attempted without an |
| 10835 | intervening command (see <B>JOB CONTROL</B> above). The shell always |
| 10836 | postpones exiting if any jobs are stopped. |
| 10837 | <DT><B>checkwinsize</B> |
| 10838 | |
| 10839 | <DD> |
| 10840 | If set, <B>bash</B> checks the window size after each command |
| 10841 | and, if necessary, updates the values of |
| 10842 | <FONT SIZE=-1><B>LINES</B> |
| 10843 | |
| 10844 | </FONT> |
| 10845 | and |
| 10846 | <FONT SIZE=-1><B>COLUMNS</B>. |
| 10847 | |
| 10848 | </FONT> |
| 10849 | <DT><B>cmdhist</B> |
| 10850 | |
| 10851 | <DD> |
| 10852 | If set, |
| 10853 | <B>bash</B> |
| 10854 | |
| 10855 | attempts to save all lines of a multiple-line |
| 10856 | command in the same history entry. This allows |
| 10857 | easy re-editing of multi-line commands. |
| 10858 | <DT><B>compat31</B> |
| 10859 | |
| 10860 | <DD> |
| 10861 | If set, |
| 10862 | <B>bash</B> |
| 10863 | |
| 10864 | changes its behavior to that of version 3.1 with respect to quoted |
| 10865 | arguments to the conditional command's =~ operator. |
| 10866 | <DT><B>dirspell</B> |
| 10867 | |
| 10868 | <DD> |
| 10869 | If set, |
| 10870 | <B>bash</B> |
| 10871 | |
| 10872 | attempts spelling correction on directory names during word completion |
| 10873 | if the directory name initially supplied does not exist. |
| 10874 | <DT><B>dotglob</B> |
| 10875 | |
| 10876 | <DD> |
| 10877 | If set, |
| 10878 | <B>bash</B> |
| 10879 | |
| 10880 | includes filenames beginning with a `.' in the results of pathname |
| 10881 | expansion. |
| 10882 | <DT><B>execfail</B> |
| 10883 | |
| 10884 | <DD> |
| 10885 | If set, a non-interactive shell will not exit if |
| 10886 | it cannot execute the file specified as an argument to the |
| 10887 | <B>exec</B> |
| 10888 | |
| 10889 | builtin command. An interactive shell does not exit if |
| 10890 | <B>exec</B> |
| 10891 | |
| 10892 | fails. |
| 10893 | <DT><B>expand_aliases</B> |
| 10894 | |
| 10895 | <DD> |
| 10896 | If set, aliases are expanded as described above under |
| 10897 | <FONT SIZE=-1><B>ALIASES</B>. |
| 10898 | |
| 10899 | </FONT> |
| 10900 | This option is enabled by default for interactive shells. |
| 10901 | <DT><B>extdebug</B> |
| 10902 | |
| 10903 | <DD> |
| 10904 | If set, behavior intended for use by debuggers is enabled: |
| 10905 | <DL COMPACT><DT><DD> |
| 10906 | <DL COMPACT> |
| 10907 | <DT><B>1.</B> |
| 10908 | |
| 10909 | <DD> |
| 10910 | The <B>-F</B> option to the <B>declare</B> builtin displays the source |
| 10911 | file name and line number corresponding to each function name supplied |
| 10912 | as an argument. |
| 10913 | <DT><B>2.</B> |
| 10914 | |
| 10915 | <DD> |
| 10916 | If the command run by the <B>DEBUG</B> trap returns a non-zero value, the |
| 10917 | next command is skipped and not executed. |
| 10918 | <DT><B>3.</B> |
| 10919 | |
| 10920 | <DD> |
| 10921 | If the command run by the <B>DEBUG</B> trap returns a value of 2, and the |
| 10922 | shell is executing in a subroutine (a shell function or a shell script |
| 10923 | executed by the <B>.</B> or <B>source</B> builtins), a call to |
| 10924 | <B>return</B> is simulated. |
| 10925 | <DT><B>4.</B> |
| 10926 | |
| 10927 | <DD> |
| 10928 | <B>BASH_ARGC</B> and <B>BASH_ARGV</B> are updated as described in their |
| 10929 | descriptions above. |
| 10930 | <DT><B>5.</B> |
| 10931 | |
| 10932 | <DD> |
| 10933 | Function tracing is enabled: command substitution, shell functions, and |
| 10934 | subshells invoked with <B>(</B> <I>command</I> <B>)</B> inherit the |
| 10935 | <B>DEBUG</B> and <B>RETURN</B> traps. |
| 10936 | <DT><B>6.</B> |
| 10937 | |
| 10938 | <DD> |
| 10939 | Error tracing is enabled: command substitution, shell functions, and |
| 10940 | subshells invoked with <B>(</B> <I>command</I> <B>)</B> inherit the |
| 10941 | <B>ERROR</B> trap. |
| 10942 | </DL></DL> |
| 10943 | |
| 10944 | <DT><B>extglob</B> |
| 10945 | |
| 10946 | <DD> |
| 10947 | If set, the extended pattern matching features described above under |
| 10948 | <B>Pathname Expansion</B> are enabled. |
| 10949 | <DT><B>extquote</B> |
| 10950 | |
| 10951 | <DD> |
| 10952 | If set, <B>$</B>aq<I>string</I>aq and <B>$</B>"<I>string</I>" quoting is |
| 10953 | performed within <B>${</B><I>parameter</I><B>}</B> expansions |
| 10954 | enclosed in double quotes. This option is enabled by default. |
| 10955 | <DT><B>failglob</B> |
| 10956 | |
| 10957 | <DD> |
| 10958 | If set, patterns which fail to match filenames during pathname expansion |
| 10959 | result in an expansion error. |
| 10960 | <DT><B>force_fignore</B> |
| 10961 | |
| 10962 | <DD> |
| 10963 | If set, the suffixes specified by the <B>FIGNORE</B> shell variable |
| 10964 | cause words to be ignored when performing word completion even if |
| 10965 | the ignored words are the only possible completions. |
| 10966 | See |
| 10967 | <FONT SIZE=-1><B>SHELL VARIABLES</B></FONT> |
| 10968 | above for a description of <B>FIGNORE</B>. |
| 10969 | This option is enabled by default. |
| 10970 | <DT><B>globstar</B> |
| 10971 | |
| 10972 | <DD> |
| 10973 | If set, the pattern <B>**</B> used in a filename expansion context will |
| 10974 | match a files and zero or more directories and subdirectories. |
| 10975 | If the pattern is followed by a <B>/</B>, only directories and |
| 10976 | subdirectories match. |
| 10977 | <DT><B>gnu_errfmt</B> |
| 10978 | |
| 10979 | <DD> |
| 10980 | If set, shell error messages are written in the standard GNU error |
| 10981 | message format. |
| 10982 | <DT><B>histappend</B> |
| 10983 | |
| 10984 | <DD> |
| 10985 | If set, the history list is appended to the file named by the value |
| 10986 | of the |
| 10987 | <B>HISTFILE</B> |
| 10988 | |
| 10989 | variable when the shell exits, rather than overwriting the file. |
| 10990 | <DT><B>histreedit</B> |
| 10991 | |
| 10992 | <DD> |
| 10993 | If set, and |
| 10994 | <B>readline</B> |
| 10995 | |
| 10996 | is being used, a user is given the opportunity to re-edit a |
| 10997 | failed history substitution. |
| 10998 | <DT><B>histverify</B> |
| 10999 | |
| 11000 | <DD> |
| 11001 | If set, and |
| 11002 | <B>readline</B> |
| 11003 | |
| 11004 | is being used, the results of history substitution are not immediately |
| 11005 | passed to the shell parser. Instead, the resulting line is loaded into |
| 11006 | the <B>readline</B> editing buffer, allowing further modification. |
| 11007 | <DT><B>hostcomplete</B> |
| 11008 | |
| 11009 | <DD> |
| 11010 | If set, and |
| 11011 | <B>readline</B> |
| 11012 | |
| 11013 | is being used, <B>bash</B> will attempt to perform hostname completion when a |
| 11014 | word containing a <B>@</B> is being completed (see |
| 11015 | <B>Completing</B> |
| 11016 | |
| 11017 | under |
| 11018 | <FONT SIZE=-1><B>READLINE</B> |
| 11019 | |
| 11020 | </FONT> |
| 11021 | above). |
| 11022 | This is enabled by default. |
| 11023 | <DT><B>huponexit</B> |
| 11024 | |
| 11025 | <DD> |
| 11026 | If set, <B>bash</B> will send |
| 11027 | <FONT SIZE=-1><B>SIGHUP</B> |
| 11028 | |
| 11029 | </FONT> |
| 11030 | to all jobs when an interactive login shell exits. |
| 11031 | <DT><B>interactive_comments</B> |
| 11032 | |
| 11033 | <DD> |
| 11034 | If set, allow a word beginning with |
| 11035 | <B>#</B> |
| 11036 | |
| 11037 | to cause that word and all remaining characters on that |
| 11038 | line to be ignored in an interactive shell (see |
| 11039 | <FONT SIZE=-1><B>COMMENTS</B> |
| 11040 | |
| 11041 | </FONT> |
| 11042 | above). This option is enabled by default. |
| 11043 | <DT><B>lithist</B> |
| 11044 | |
| 11045 | <DD> |
| 11046 | If set, and the |
| 11047 | <B>cmdhist</B> |
| 11048 | |
| 11049 | option is enabled, multi-line commands are saved to the history with |
| 11050 | embedded newlines rather than using semicolon separators where possible. |
| 11051 | <DT><B>login_shell</B> |
| 11052 | |
| 11053 | <DD> |
| 11054 | The shell sets this option if it is started as a login shell (see |
| 11055 | <FONT SIZE=-1><B>INVOCATION</B> |
| 11056 | |
| 11057 | </FONT> |
| 11058 | above). |
| 11059 | The value may not be changed. |
| 11060 | <DT><B>mailwarn</B> |
| 11061 | |
| 11062 | <DD> |
| 11063 | If set, and a file that <B>bash</B> is checking for mail has been |
| 11064 | accessed since the last time it was checked, the message ``The mail in |
| 11065 | <I>mailfile</I> has been read'' is displayed. |
| 11066 | <DT><B>no_empty_cmd_completion</B> |
| 11067 | |
| 11068 | <DD> |
| 11069 | If set, and |
| 11070 | <B>readline</B> |
| 11071 | |
| 11072 | is being used, |
| 11073 | <B>bash</B> |
| 11074 | |
| 11075 | will not attempt to search the <B>PATH</B> for possible completions when |
| 11076 | completion is attempted on an empty line. |
| 11077 | <DT><B>nocaseglob</B> |
| 11078 | |
| 11079 | <DD> |
| 11080 | If set, |
| 11081 | <B>bash</B> |
| 11082 | |
| 11083 | matches filenames in a case-insensitive fashion when performing pathname |
| 11084 | expansion (see |
| 11085 | <B>Pathname Expansion</B> |
| 11086 | |
| 11087 | above). |
| 11088 | <DT><B>nocasematch</B> |
| 11089 | |
| 11090 | <DD> |
| 11091 | If set, |
| 11092 | <B>bash</B> |
| 11093 | |
| 11094 | matches patterns in a case-insensitive fashion when performing matching |
| 11095 | while executing <B>case</B> or <B>[[</B> conditional commands. |
| 11096 | <DT><B>nullglob</B> |
| 11097 | |
| 11098 | <DD> |
| 11099 | If set, |
| 11100 | <B>bash</B> |
| 11101 | |
| 11102 | allows patterns which match no |
| 11103 | files (see |
| 11104 | <B>Pathname Expansion</B> |
| 11105 | |
| 11106 | above) |
| 11107 | to expand to a null string, rather than themselves. |
| 11108 | <DT><B>progcomp</B> |
| 11109 | |
| 11110 | <DD> |
| 11111 | If set, the programmable completion facilities (see |
| 11112 | <B>Programmable Completion</B> above) are enabled. |
| 11113 | This option is enabled by default. |
| 11114 | <DT><B>promptvars</B> |
| 11115 | |
| 11116 | <DD> |
| 11117 | If set, prompt strings undergo |
| 11118 | parameter expansion, command substitution, arithmetic |
| 11119 | expansion, and quote removal after being expanded as described in |
| 11120 | <FONT SIZE=-1><B>PROMPTING</B> |
| 11121 | |
| 11122 | </FONT> |
| 11123 | above. This option is enabled by default. |
| 11124 | <DT><B>restricted_shell</B> |
| 11125 | |
| 11126 | <DD> |
| 11127 | The shell sets this option if it is started in restricted mode (see |
| 11128 | <FONT SIZE=-1><B>RESTRICTED SHELL</B> |
| 11129 | |
| 11130 | </FONT> |
| 11131 | below). |
| 11132 | The value may not be changed. |
| 11133 | This is not reset when the startup files are executed, allowing |
| 11134 | the startup files to discover whether or not a shell is restricted. |
| 11135 | <DT><B>shift_verbose</B> |
| 11136 | |
| 11137 | <DD> |
| 11138 | If set, the |
| 11139 | <B>shift</B> |
| 11140 | |
| 11141 | builtin prints an error message when the shift count exceeds the |
| 11142 | number of positional parameters. |
| 11143 | <DT><B>sourcepath</B> |
| 11144 | |
| 11145 | <DD> |
| 11146 | If set, the |
| 11147 | <B>source</B> (<B>.</B>) builtin uses the value of |
| 11148 | <FONT SIZE=-1><B>PATH</B> |
| 11149 | |
| 11150 | </FONT> |
| 11151 | to find the directory containing the file supplied as an argument. |
| 11152 | This option is enabled by default. |
| 11153 | <DT><B>xpg_echo</B> |
| 11154 | |
| 11155 | <DD> |
| 11156 | If set, the <B>echo</B> builtin expands backslash-escape sequences |
| 11157 | by default. |
| 11158 | </DL></DL> |
| 11159 | |
| 11160 | <DT><B>suspend</B> [<B>-f</B>]<DD> |
| 11161 | Suspend the execution of this shell until it receives a |
| 11162 | <FONT SIZE=-1><B>SIGCONT</B> |
| 11163 | |
| 11164 | </FONT> |
| 11165 | signal. A login shell cannot be suspended; the |
| 11166 | <B>-f</B> |
| 11167 | |
| 11168 | option can be used to override this and force the suspension. |
| 11169 | The return status is 0 unless the shell is a login shell and |
| 11170 | <B>-f</B> |
| 11171 | |
| 11172 | is not supplied, or if job control is not enabled. |
| 11173 | <DT><B>test</B> <I>expr</I><DD> |
| 11174 | |
| 11175 | <DT><B>[</B> <I>expr</I> <B>]</B><DD> |
| 11176 | Return a status of 0 or 1 depending on |
| 11177 | the evaluation of the conditional expression |
| 11178 | <I>expr</I>. |
| 11179 | |
| 11180 | Each operator and operand must be a separate argument. |
| 11181 | Expressions are composed of the primaries described above under |
| 11182 | <FONT SIZE=-1><B>CONDITIONAL EXPRESSIONS</B>. |
| 11183 | |
| 11184 | </FONT> |
| 11185 | <B>test</B> does not accept any options, nor does it accept and ignore |
| 11186 | an argument of <B>--</B> as signifying the end of options. |
| 11187 | <P> |
| 11188 | |
| 11189 | |
| 11190 | Expressions may be combined using the following operators, listed |
| 11191 | in decreasing order of precedence. |
| 11192 | The evaluation depends on the number of arguments; see below. |
| 11193 | <DL COMPACT><DT><DD> |
| 11194 | |
| 11195 | <DL COMPACT> |
| 11196 | <DT><B>! </B><I>expr</I> |
| 11197 | |
| 11198 | <DD> |
| 11199 | True if |
| 11200 | <I>expr</I> |
| 11201 | |
| 11202 | is false. |
| 11203 | <DT><B>( </B><I>expr</I> ) |
| 11204 | |
| 11205 | <DD> |
| 11206 | Returns the value of <I>expr</I>. |
| 11207 | This may be used to override the normal precedence of operators. |
| 11208 | <DT><I>expr1</I> -<B>a</B> <I>expr2</I><DD> |
| 11209 | True if both |
| 11210 | <I>expr1</I> |
| 11211 | |
| 11212 | and |
| 11213 | <I>expr2</I> |
| 11214 | |
| 11215 | are true. |
| 11216 | <DT><I>expr1</I> -<B>o</B> <I>expr2</I><DD> |
| 11217 | True if either |
| 11218 | <I>expr1</I> |
| 11219 | |
| 11220 | or |
| 11221 | <I>expr2</I> |
| 11222 | |
| 11223 | is true. |
| 11224 | |
| 11225 | </DL> |
| 11226 | <P> |
| 11227 | |
| 11228 | <B>test</B> and <B>[</B> evaluate conditional |
| 11229 | expressions using a set of rules based on the number of arguments. |
| 11230 | <P> |
| 11231 | |
| 11232 | |
| 11233 | |
| 11234 | <DL COMPACT> |
| 11235 | <DT>0 arguments<DD> |
| 11236 | The expression is false. |
| 11237 | <DT>1 argument<DD> |
| 11238 | The expression is true if and only if the argument is not null. |
| 11239 | <DT>2 arguments<DD> |
| 11240 | If the first argument is <B>!</B>, the expression is true if and |
| 11241 | only if the second argument is null. |
| 11242 | If the first argument is one of the unary conditional operators listed above |
| 11243 | under |
| 11244 | <FONT SIZE=-1><B>CONDITIONAL EXPRESSIONS</B>, |
| 11245 | |
| 11246 | </FONT> |
| 11247 | the expression is true if the unary test is true. |
| 11248 | If the first argument is not a valid unary conditional operator, the expression |
| 11249 | is false. |
| 11250 | <DT>3 arguments<DD> |
| 11251 | If the second argument is one of the binary conditional operators listed above |
| 11252 | under |
| 11253 | <FONT SIZE=-1><B>CONDITIONAL EXPRESSIONS</B>, |
| 11254 | |
| 11255 | </FONT> |
| 11256 | the result of the expression is the result of the binary test using |
| 11257 | the first and third arguments as operands. |
| 11258 | The <B>-a</B> and <B>-o</B> operators are considered binary operators |
| 11259 | when there are three arguments. |
| 11260 | If the first argument is <B>!</B>, the value is the negation of |
| 11261 | the two-argument test using the second and third arguments. |
| 11262 | If the first argument is exactly <B>(</B> and the third argument is |
| 11263 | exactly <B>)</B>, the result is the one-argument test of the second |
| 11264 | argument. |
| 11265 | Otherwise, the expression is false. |
| 11266 | <DT>4 arguments<DD> |
| 11267 | If the first argument is <B>!</B>, the result is the negation of |
| 11268 | the three-argument expression composed of the remaining arguments. |
| 11269 | Otherwise, the expression is parsed and evaluated according to |
| 11270 | precedence using the rules listed above. |
| 11271 | <DT>5 or more arguments<DD> |
| 11272 | The expression is parsed and evaluated according to precedence |
| 11273 | using the rules listed above. |
| 11274 | </DL></DL> |
| 11275 | |
| 11276 | |
| 11277 | <DT><B>times</B> |
| 11278 | |
| 11279 | <DD> |
| 11280 | Print the accumulated user and system times for the shell and |
| 11281 | for processes run from the shell. The return status is 0. |
| 11282 | <DT><B>trap</B> [<B>-lp</B>] [[<I>arg</I>] <I>sigspec</I> ...]<DD> |
| 11283 | The command |
| 11284 | <I>arg</I> |
| 11285 | |
| 11286 | is to be read and executed when the shell receives |
| 11287 | signal(s) |
| 11288 | <I>sigspec</I>. |
| 11289 | |
| 11290 | If |
| 11291 | <I>arg</I> |
| 11292 | |
| 11293 | is absent (and there is a single <I>sigspec</I>) or |
| 11294 | <B>-</B>, |
| 11295 | |
| 11296 | each specified signal is |
| 11297 | reset to its original disposition (the value it had |
| 11298 | upon entrance to the shell). |
| 11299 | If |
| 11300 | <I>arg</I> |
| 11301 | |
| 11302 | is the null string the signal specified by each |
| 11303 | <I>sigspec</I> |
| 11304 | |
| 11305 | is ignored by the shell and by the commands it invokes. |
| 11306 | If |
| 11307 | <I>arg</I> |
| 11308 | |
| 11309 | is not present and |
| 11310 | <B>-p</B> |
| 11311 | |
| 11312 | has been supplied, then the trap commands associated with each |
| 11313 | <I>sigspec</I> |
| 11314 | |
| 11315 | are displayed. |
| 11316 | If no arguments are supplied or if only |
| 11317 | <B>-p</B> |
| 11318 | |
| 11319 | is given, |
| 11320 | <B>trap</B> |
| 11321 | |
| 11322 | prints the list of commands associated with each signal. |
| 11323 | The |
| 11324 | <B>-l</B> |
| 11325 | |
| 11326 | option causes the shell to print a list of signal names and |
| 11327 | their corresponding numbers. |
| 11328 | Each |
| 11329 | <I>sigspec</I> |
| 11330 | |
| 11331 | is either |
| 11332 | a signal name defined in <<I>signal.h</I>>, or a signal number. |
| 11333 | Signal names are case insensitive and the SIG prefix is optional. |
| 11334 | If a |
| 11335 | <I>sigspec</I> |
| 11336 | |
| 11337 | is |
| 11338 | <FONT SIZE=-1><B>EXIT</B> |
| 11339 | |
| 11340 | </FONT> |
| 11341 | (0) the command |
| 11342 | <I>arg</I> |
| 11343 | |
| 11344 | is executed on exit from the shell. |
| 11345 | If a |
| 11346 | <I>sigspec</I> |
| 11347 | |
| 11348 | is |
| 11349 | <FONT SIZE=-1><B>DEBUG</B>, |
| 11350 | |
| 11351 | </FONT> |
| 11352 | the command |
| 11353 | <I>arg</I> |
| 11354 | |
| 11355 | is executed before every <I>simple command</I>, <I>for</I> command, |
| 11356 | <I>case</I> command, <I>select</I> command, every arithmetic <I>for</I> |
| 11357 | command, and before the first command executes in a shell function (see |
| 11358 | <FONT SIZE=-1><B>SHELL GRAMMAR</B> |
| 11359 | |
| 11360 | </FONT> |
| 11361 | above). |
| 11362 | Refer to the description of the <B>extdebug</B> option to the |
| 11363 | <B>shopt</B> builtin for details of its effect on the <B>DEBUG</B> trap. |
| 11364 | If a |
| 11365 | <I>sigspec</I> |
| 11366 | |
| 11367 | is |
| 11368 | <FONT SIZE=-1><B>ERR</B>, |
| 11369 | |
| 11370 | </FONT> |
| 11371 | the command |
| 11372 | <I>arg</I> |
| 11373 | |
| 11374 | is executed whenever a simple command has a non-zero exit status, |
| 11375 | subject to the following conditions. |
| 11376 | The |
| 11377 | <FONT SIZE=-1><B>ERR</B> |
| 11378 | |
| 11379 | </FONT> |
| 11380 | trap is not executed if the failed |
| 11381 | command is part of the command list immediately following a |
| 11382 | <B>while</B> |
| 11383 | |
| 11384 | or |
| 11385 | <B>until</B> |
| 11386 | |
| 11387 | keyword, |
| 11388 | part of the test in an |
| 11389 | <I>if</I> |
| 11390 | |
| 11391 | statement, part of a command executed in a |
| 11392 | <B>&&</B> |
| 11393 | |
| 11394 | or |
| 11395 | <B>||</B> |
| 11396 | |
| 11397 | list, or if the command's return value is |
| 11398 | being inverted via |
| 11399 | <B>!</B>. |
| 11400 | |
| 11401 | These are the same conditions obeyed by the <B>errexit</B> option. |
| 11402 | If a |
| 11403 | <I>sigspec</I> |
| 11404 | |
| 11405 | is |
| 11406 | <FONT SIZE=-1><B>RETURN</B>, |
| 11407 | |
| 11408 | </FONT> |
| 11409 | the command |
| 11410 | <I>arg</I> |
| 11411 | |
| 11412 | is executed each time a shell function or a script executed with the |
| 11413 | <B>.</B> or <B>source</B> builtins finishes executing. |
| 11414 | Signals ignored upon entry to the shell cannot be trapped or reset. |
| 11415 | Trapped signals that are not being ignored are reset to their original |
| 11416 | values in a child process when it is created. |
| 11417 | The return status is false if any |
| 11418 | <I>sigspec</I> |
| 11419 | |
| 11420 | is invalid; otherwise |
| 11421 | <B>trap</B> |
| 11422 | |
| 11423 | returns true. |
| 11424 | <DT><B>type</B> [<B>-aftpP</B>] <I>name</I> [<I>name</I> ...]<DD> |
| 11425 | With no options, |
| 11426 | indicate how each |
| 11427 | <I>name</I> |
| 11428 | |
| 11429 | would be interpreted if used as a command name. |
| 11430 | If the |
| 11431 | <B>-t</B> |
| 11432 | |
| 11433 | option is used, |
| 11434 | <B>type</B> |
| 11435 | |
| 11436 | prints a string which is one of |
| 11437 | <I>alias</I>, |
| 11438 | |
| 11439 | <I>keyword</I>, |
| 11440 | |
| 11441 | <I>function</I>, |
| 11442 | |
| 11443 | <I>builtin</I>, |
| 11444 | |
| 11445 | or |
| 11446 | <I>file </I> |
| 11447 | |
| 11448 | if |
| 11449 | <I>name</I> |
| 11450 | |
| 11451 | is an alias, shell reserved word, function, builtin, or disk file, |
| 11452 | respectively. |
| 11453 | If the |
| 11454 | <I>name</I> |
| 11455 | |
| 11456 | is not found, then nothing is printed, and an exit status of false |
| 11457 | is returned. |
| 11458 | If the |
| 11459 | <B>-p</B> |
| 11460 | |
| 11461 | option is used, |
| 11462 | <B>type</B> |
| 11463 | |
| 11464 | either returns the name of the disk file |
| 11465 | that would be executed if |
| 11466 | <I>name</I> |
| 11467 | |
| 11468 | were specified as a command name, |
| 11469 | or nothing if |
| 11470 | <TT>type -t name</TT> |
| 11471 | |
| 11472 | would not return |
| 11473 | <I>file</I>. |
| 11474 | |
| 11475 | The |
| 11476 | <B>-P</B> |
| 11477 | |
| 11478 | option forces a |
| 11479 | <FONT SIZE=-1><B>PATH</B> |
| 11480 | |
| 11481 | </FONT> |
| 11482 | search for each <I>name</I>, even if |
| 11483 | <TT>type -t name</TT> |
| 11484 | |
| 11485 | would not return |
| 11486 | <I>file</I>. |
| 11487 | |
| 11488 | If a command is hashed, |
| 11489 | <B>-p</B> |
| 11490 | |
| 11491 | and |
| 11492 | <B>-P</B> |
| 11493 | |
| 11494 | print the hashed value, not necessarily the file that appears |
| 11495 | first in |
| 11496 | <FONT SIZE=-1><B>PATH</B>. |
| 11497 | |
| 11498 | </FONT> |
| 11499 | If the |
| 11500 | <B>-a</B> |
| 11501 | |
| 11502 | option is used, |
| 11503 | <B>type</B> |
| 11504 | |
| 11505 | prints all of the places that contain |
| 11506 | an executable named |
| 11507 | <I>name</I>. |
| 11508 | |
| 11509 | This includes aliases and functions, |
| 11510 | if and only if the |
| 11511 | <B>-p</B> |
| 11512 | |
| 11513 | option is not also used. |
| 11514 | The table of hashed commands is not consulted |
| 11515 | when using |
| 11516 | <B>-a</B>. |
| 11517 | |
| 11518 | The |
| 11519 | <B>-f</B> |
| 11520 | |
| 11521 | option suppresses shell function lookup, as with the <B>command</B> builtin. |
| 11522 | <B>type</B> |
| 11523 | |
| 11524 | returns true if all of the arguments are found, false if |
| 11525 | any are not found. |
| 11526 | <DT><B>ulimit</B> [<B>-HSTabcdefilmnpqrstuvx</B> [<I>limit</I>]]<DD> |
| 11527 | Provides control over the resources available to the shell and to |
| 11528 | processes started by it, on systems that allow such control. |
| 11529 | The <B>-H</B> and <B>-S</B> options specify that the hard or soft limit is |
| 11530 | set for the given resource. |
| 11531 | A hard limit cannot be increased by a non-root user once it is set; |
| 11532 | a soft limit may be increased up to the value of the hard limit. |
| 11533 | If neither <B>-H</B> nor <B>-S</B> is specified, both the soft and hard |
| 11534 | limits are set. |
| 11535 | The value of |
| 11536 | <I>limit</I> |
| 11537 | |
| 11538 | can be a number in the unit specified for the resource |
| 11539 | or one of the special values |
| 11540 | <B>hard</B>, |
| 11541 | |
| 11542 | <B>soft</B>, |
| 11543 | |
| 11544 | or |
| 11545 | <B>unlimited</B>, |
| 11546 | |
| 11547 | which stand for the current hard limit, the current soft limit, and |
| 11548 | no limit, respectively. |
| 11549 | If |
| 11550 | <I>limit</I> |
| 11551 | |
| 11552 | is omitted, the current value of the soft limit of the resource is |
| 11553 | printed, unless the <B>-H</B> option is given. When more than one |
| 11554 | resource is specified, the limit name and unit are printed before the value. |
| 11555 | Other options are interpreted as follows: |
| 11556 | <DL COMPACT><DT><DD> |
| 11557 | |
| 11558 | <DL COMPACT> |
| 11559 | <DT><B>-a</B> |
| 11560 | |
| 11561 | <DD> |
| 11562 | All current limits are reported |
| 11563 | <DT><B>-b</B> |
| 11564 | |
| 11565 | <DD> |
| 11566 | The maximum socket buffer size |
| 11567 | <DT><B>-c</B> |
| 11568 | |
| 11569 | <DD> |
| 11570 | The maximum size of core files created |
| 11571 | <DT><B>-d</B> |
| 11572 | |
| 11573 | <DD> |
| 11574 | The maximum size of a process's data segment |
| 11575 | <DT><B>-e</B> |
| 11576 | |
| 11577 | <DD> |
| 11578 | The maximum scheduling priority ("nice") |
| 11579 | <DT><B>-f</B> |
| 11580 | |
| 11581 | <DD> |
| 11582 | The maximum size of files written by the shell and its children |
| 11583 | <DT><B>-i</B> |
| 11584 | |
| 11585 | <DD> |
| 11586 | The maximum number of pending signals |
| 11587 | <DT><B>-l</B> |
| 11588 | |
| 11589 | <DD> |
| 11590 | The maximum size that may be locked into memory |
| 11591 | <DT><B>-m</B> |
| 11592 | |
| 11593 | <DD> |
| 11594 | The maximum resident set size |
| 11595 | <DT><B>-n</B> |
| 11596 | |
| 11597 | <DD> |
| 11598 | The maximum number of open file descriptors (most systems do not |
| 11599 | allow this value to be set) |
| 11600 | <DT><B>-p</B> |
| 11601 | |
| 11602 | <DD> |
| 11603 | The pipe size in 512-byte blocks (this may not be set) |
| 11604 | <DT><B>-q</B> |
| 11605 | |
| 11606 | <DD> |
| 11607 | The maximum number of bytes in POSIX message queues |
| 11608 | <DT><B>-r</B> |
| 11609 | |
| 11610 | <DD> |
| 11611 | The maximum real-time scheduling priority |
| 11612 | <DT><B>-s</B> |
| 11613 | |
| 11614 | <DD> |
| 11615 | The maximum stack size |
| 11616 | <DT><B>-t</B> |
| 11617 | |
| 11618 | <DD> |
| 11619 | The maximum amount of cpu time in seconds |
| 11620 | <DT><B>-u</B> |
| 11621 | |
| 11622 | <DD> |
| 11623 | The maximum number of processes available to a single user |
| 11624 | <DT><B>-v</B> |
| 11625 | |
| 11626 | <DD> |
| 11627 | The maximum amount of virtual memory available to the shell |
| 11628 | <DT><B>-x</B> |
| 11629 | |
| 11630 | <DD> |
| 11631 | The maximum number of file locks |
| 11632 | <DT><B>-T</B> |
| 11633 | |
| 11634 | <DD> |
| 11635 | The maximum number of threads |
| 11636 | |
| 11637 | </DL> |
| 11638 | <P> |
| 11639 | |
| 11640 | If |
| 11641 | <I>limit</I> |
| 11642 | |
| 11643 | is given, it is the new value of the specified resource (the |
| 11644 | <B>-a</B> |
| 11645 | |
| 11646 | option is display only). |
| 11647 | If no option is given, then |
| 11648 | <B>-f</B> |
| 11649 | |
| 11650 | is assumed. Values are in 1024-byte increments, except for |
| 11651 | <B>-t</B>, |
| 11652 | |
| 11653 | which is in seconds, |
| 11654 | <B>-p</B>, |
| 11655 | |
| 11656 | which is in units of 512-byte blocks, |
| 11657 | and |
| 11658 | <B>-T</B>, |
| 11659 | |
| 11660 | <B>-b</B>, |
| 11661 | |
| 11662 | <B>-n</B>, |
| 11663 | |
| 11664 | and |
| 11665 | <B>-u</B>, |
| 11666 | |
| 11667 | which are unscaled values. |
| 11668 | The return status is 0 unless an invalid option or argument is supplied, |
| 11669 | or an error occurs while setting a new limit. |
| 11670 | </DL> |
| 11671 | |
| 11672 | <DT><B>umask</B> [<B>-p</B>] [<B>-S</B>] [<I>mode</I>]<DD> |
| 11673 | The user file-creation mask is set to |
| 11674 | <I>mode</I>. |
| 11675 | |
| 11676 | If |
| 11677 | <I>mode</I> |
| 11678 | |
| 11679 | begins with a digit, it |
| 11680 | is interpreted as an octal number; otherwise |
| 11681 | it is interpreted as a symbolic mode mask similar |
| 11682 | to that accepted by |
| 11683 | <I>chmod</I>(1). |
| 11684 | |
| 11685 | If |
| 11686 | <I>mode</I> |
| 11687 | |
| 11688 | is omitted, the current value of the mask is printed. |
| 11689 | The |
| 11690 | <B>-S</B> |
| 11691 | |
| 11692 | option causes the mask to be printed in symbolic form; the |
| 11693 | default output is an octal number. |
| 11694 | If the |
| 11695 | <B>-p</B> |
| 11696 | |
| 11697 | option is supplied, and |
| 11698 | <I>mode</I> |
| 11699 | |
| 11700 | is omitted, the output is in a form that may be reused as input. |
| 11701 | The return status is 0 if the mode was successfully changed or if |
| 11702 | no <I>mode</I> argument was supplied, and false otherwise. |
| 11703 | <DT><B>unalias</B> [-<B>a</B>] [<I>name</I> ...]<DD> |
| 11704 | Remove each <I>name</I> from the list of defined aliases. If |
| 11705 | <B>-a</B> |
| 11706 | |
| 11707 | is supplied, all alias definitions are removed. The return |
| 11708 | value is true unless a supplied |
| 11709 | <I>name</I> |
| 11710 | |
| 11711 | is not a defined alias. |
| 11712 | <DT><B>unset</B> [-<B>fv</B>] [<I>name</I> ...]<DD> |
| 11713 | For each |
| 11714 | <I>name</I>, |
| 11715 | |
| 11716 | remove the corresponding variable or function. |
| 11717 | If no options are supplied, or the |
| 11718 | <B>-v</B> |
| 11719 | |
| 11720 | option is given, each |
| 11721 | <I>name</I> |
| 11722 | |
| 11723 | refers to a shell variable. |
| 11724 | Read-only variables may not be unset. |
| 11725 | If |
| 11726 | <B>-f</B> |
| 11727 | |
| 11728 | is specified, each |
| 11729 | <I>name</I> |
| 11730 | |
| 11731 | refers to a shell function, and the function definition |
| 11732 | is removed. |
| 11733 | Each unset variable or function is removed from the environment |
| 11734 | passed to subsequent commands. |
| 11735 | If any of |
| 11736 | <FONT SIZE=-1><B>RANDOM</B>, |
| 11737 | |
| 11738 | </FONT> |
| 11739 | <FONT SIZE=-1><B>SECONDS</B>, |
| 11740 | |
| 11741 | </FONT> |
| 11742 | <FONT SIZE=-1><B>LINENO</B>, |
| 11743 | |
| 11744 | </FONT> |
| 11745 | <FONT SIZE=-1><B>HISTCMD</B>, |
| 11746 | |
| 11747 | </FONT> |
| 11748 | <FONT SIZE=-1><B>FUNCNAME</B>, |
| 11749 | |
| 11750 | </FONT> |
| 11751 | <FONT SIZE=-1><B>GROUPS</B>, |
| 11752 | |
| 11753 | </FONT> |
| 11754 | or |
| 11755 | <FONT SIZE=-1><B>DIRSTACK</B> |
| 11756 | |
| 11757 | </FONT> |
| 11758 | are unset, they lose their special properties, even if they are |
| 11759 | subsequently reset. The exit status is true unless a |
| 11760 | <I>name</I> |
| 11761 | |
| 11762 | is readonly. |
| 11763 | <DT><B>wait</B> [<I>n ...</I>]<DD> |
| 11764 | Wait for each specified process and return its termination status. |
| 11765 | Each |
| 11766 | <I>n</I> |
| 11767 | |
| 11768 | may be a process |
| 11769 | ID or a job specification; if a job spec is given, all processes |
| 11770 | in that job's pipeline are waited for. If |
| 11771 | <I>n</I> |
| 11772 | |
| 11773 | is not given, all currently active child processes |
| 11774 | are waited for, and the return status is zero. If |
| 11775 | <I>n</I> |
| 11776 | |
| 11777 | specifies a non-existent process or job, the return status is |
| 11778 | 127. Otherwise, the return status is the exit status of the last |
| 11779 | process or job waited for. |
| 11780 | |
| 11781 | |
| 11782 | </DL> |
| 11783 | <A NAME="lbDC"> </A> |
| 11784 | <H3>RESTRICTED SHELL</H3> |
| 11785 | |
| 11786 | |
| 11787 | |
| 11788 | <P> |
| 11789 | |
| 11790 | If |
| 11791 | <B>bash</B> |
| 11792 | |
| 11793 | is started with the name |
| 11794 | <B>rbash</B>, |
| 11795 | |
| 11796 | or the |
| 11797 | <B>-r</B> |
| 11798 | |
| 11799 | option is supplied at invocation, |
| 11800 | the shell becomes restricted. |
| 11801 | A restricted shell is used to |
| 11802 | set up an environment more controlled than the standard shell. |
| 11803 | It behaves identically to |
| 11804 | <B>bash</B> |
| 11805 | |
| 11806 | with the exception that the following are disallowed or not performed: |
| 11807 | <DL COMPACT> |
| 11808 | <DT>*<DD> |
| 11809 | changing directories with <B>cd</B> |
| 11810 | <DT>*<DD> |
| 11811 | setting or unsetting the values of |
| 11812 | <B>SHELL</B>, |
| 11813 | |
| 11814 | <B>PATH</B>, |
| 11815 | |
| 11816 | <B>ENV</B>, |
| 11817 | |
| 11818 | or |
| 11819 | <B>BASH_ENV</B> |
| 11820 | |
| 11821 | <DT>*<DD> |
| 11822 | specifying command names containing |
| 11823 | <B>/</B> |
| 11824 | |
| 11825 | <DT>*<DD> |
| 11826 | specifying a file name containing a |
| 11827 | <B>/</B> |
| 11828 | |
| 11829 | as an argument to the |
| 11830 | <B>.</B> |
| 11831 | |
| 11832 | builtin command |
| 11833 | <DT>*<DD> |
| 11834 | Specifying a filename containing a slash as an argument to the |
| 11835 | <B>-p</B> |
| 11836 | |
| 11837 | option to the |
| 11838 | <B>hash</B> |
| 11839 | |
| 11840 | builtin command |
| 11841 | <DT>*<DD> |
| 11842 | importing function definitions from the shell environment at startup |
| 11843 | <DT>*<DD> |
| 11844 | parsing the value of <B>SHELLOPTS</B> from the shell environment at startup |
| 11845 | <DT>*<DD> |
| 11846 | redirecting output using the >, >|, <>, >&, &>, and >> redirection operators |
| 11847 | <DT>*<DD> |
| 11848 | using the |
| 11849 | <B>exec</B> |
| 11850 | |
| 11851 | builtin command to replace the shell with another command |
| 11852 | <DT>*<DD> |
| 11853 | adding or deleting builtin commands with the |
| 11854 | <B>-f</B> |
| 11855 | |
| 11856 | and |
| 11857 | <B>-d</B> |
| 11858 | |
| 11859 | options to the |
| 11860 | <B>enable</B> |
| 11861 | |
| 11862 | builtin command |
| 11863 | <DT>*<DD> |
| 11864 | Using the <B>enable</B> builtin command to enable disabled shell builtins |
| 11865 | <DT>*<DD> |
| 11866 | specifying the |
| 11867 | <B>-p</B> |
| 11868 | |
| 11869 | option to the |
| 11870 | <B>command</B> |
| 11871 | |
| 11872 | builtin command |
| 11873 | <DT>*<DD> |
| 11874 | turning off restricted mode with |
| 11875 | <B>set +r</B> or <B>set +o restricted</B>. |
| 11876 | </DL> |
| 11877 | <P> |
| 11878 | |
| 11879 | These restrictions are enforced after any startup files are read. |
| 11880 | <P> |
| 11881 | |
| 11882 | |
| 11883 | When a command that is found to be a shell script is executed |
| 11884 | (see |
| 11885 | <FONT SIZE=-1><B>COMMAND EXECUTION</B> |
| 11886 | |
| 11887 | </FONT> |
| 11888 | |
| 11889 | above), |
| 11890 | |
| 11891 | <B>rbash</B> |
| 11892 | |
| 11893 | turns off any restrictions in the shell spawned to execute the |
| 11894 | script. |
| 11895 | |
| 11896 | |
| 11897 | <A NAME="lbDD"> </A> |
| 11898 | <H3>SEE ALSO</H3> |
| 11899 | |
| 11900 | |
| 11901 | <DL COMPACT> |
| 11902 | <DT><I>Bash Reference Manual</I>, Brian Fox and Chet Ramey<DD> |
| 11903 | <DT><I>The Gnu Readline Library</I>, Brian Fox and Chet Ramey<DD> |
| 11904 | <DT><I>The Gnu History Library</I>, Brian Fox and Chet Ramey<DD> |
| 11905 | <DT><I>Portable Operating System Interface (POSIX) Part 2: Shell and Utilities</I>, IEEE<DD> |
| 11906 | <DT><I>sh</I>(1), <I>ksh</I>(1), <I>csh</I>(1)<DD> |
| 11907 | <DT><I>emacs</I>(1), <I>vi</I>(1)<DD> |
| 11908 | <DT><I>readline</I>(3)<DD> |
| 11909 | |
| 11910 | </DL> |
| 11911 | <A NAME="lbDE"> </A> |
| 11912 | <H3>FILES</H3> |
| 11913 | |
| 11914 | |
| 11915 | <DL COMPACT> |
| 11916 | <DT> |
| 11917 | <A HREF="file:/bin/bash"><I>/bin/bash</I></A> |
| 11918 | |
| 11919 | <DD> |
| 11920 | The <B>bash</B> executable |
| 11921 | <DT> |
| 11922 | <A HREF="file:/etc/profile"><I>/etc/profile</I></A> |
| 11923 | |
| 11924 | <DD> |
| 11925 | The systemwide initialization file, executed for login shells |
| 11926 | <DT> |
| 11927 | <A HREF="file:~/.bash_profile"><I>~/.bash_profile</I></A> |
| 11928 | |
| 11929 | <DD> |
| 11930 | The personal initialization file, executed for login shells |
| 11931 | <DT> |
| 11932 | <A HREF="file:~/.bashrc"><I>~/.bashrc</I></A> |
| 11933 | |
| 11934 | <DD> |
| 11935 | The individual per-interactive-shell startup file |
| 11936 | <DT> |
| 11937 | <A HREF="file:~/.bash_logout"><I>~/.bash_logout</I></A> |
| 11938 | |
| 11939 | <DD> |
| 11940 | The individual login shell cleanup file, executed when a login shell exits |
| 11941 | <DT> |
| 11942 | <A HREF="file:~/.inputrc"><I>~/.inputrc</I></A> |
| 11943 | |
| 11944 | <DD> |
| 11945 | Individual <I>readline</I> initialization file |
| 11946 | |
| 11947 | </DL> |
| 11948 | <A NAME="lbDF"> </A> |
| 11949 | <H3>AUTHORS</H3> |
| 11950 | |
| 11951 | Brian Fox, Free Software Foundation |
| 11952 | <BR> |
| 11953 | |
| 11954 | <A HREF="mailto:bfox@gnu.org">bfox@gnu.org</A> |
| 11955 | <P> |
| 11956 | |
| 11957 | Chet Ramey, Case Western Reserve University |
| 11958 | <BR> |
| 11959 | |
| 11960 | <A HREF="mailto:chet@po.cwru.edu">chet@po.cwru.edu</A> |
| 11961 | <A NAME="lbDG"> </A> |
| 11962 | <H3>BUG REPORTS</H3> |
| 11963 | |
| 11964 | If you find a bug in |
| 11965 | <B>bash,</B> |
| 11966 | |
| 11967 | you should report it. But first, you should |
| 11968 | make sure that it really is a bug, and that it appears in the latest |
| 11969 | version of |
| 11970 | <B>bash</B>. |
| 11971 | |
| 11972 | The latest version is always available from |
| 11973 | <I><A HREF="ftp://ftp.gnu.org/pub/bash/">ftp://ftp.gnu.org/pub/bash/</A></I>. |
| 11974 | <P> |
| 11975 | |
| 11976 | Once you have determined that a bug actually exists, use the |
| 11977 | <I>bashbug</I> |
| 11978 | |
| 11979 | command to submit a bug report. |
| 11980 | If you have a fix, you are encouraged to mail that as well! |
| 11981 | Suggestions and `philosophical' bug reports may be mailed |
| 11982 | to <I><A HREF="mailto:bug-bash@gnu.org">bug-bash@gnu.org</A></I> or posted to the Usenet |
| 11983 | newsgroup |
| 11984 | <A HREF="news:gnu.bash.bug">gnu.bash.bug</A>. |
| 11985 | |
| 11986 | <P> |
| 11987 | |
| 11988 | ALL bug reports should include: |
| 11989 | <P> |
| 11990 | |
| 11991 | |
| 11992 | <DL COMPACT> |
| 11993 | <DT>The version number of <B>bash</B><DD> |
| 11994 | <DT>The hardware and operating system<DD> |
| 11995 | <DT>The compiler used to compile<DD> |
| 11996 | <DT>A description of the bug behaviour<DD> |
| 11997 | <DT>A short script or `recipe' which exercises the bug<DD> |
| 11998 | |
| 11999 | </DL> |
| 12000 | <P> |
| 12001 | |
| 12002 | <I>bashbug</I> |
| 12003 | |
| 12004 | inserts the first three items automatically into the template |
| 12005 | it provides for filing a bug report. |
| 12006 | <P> |
| 12007 | |
| 12008 | Comments and bug reports concerning |
| 12009 | this manual page should be directed to |
| 12010 | <I><A HREF="mailto:chet@po.cwru.edu">chet@po.cwru.edu</A></I>. |
| 12011 | |
| 12012 | <A NAME="lbDH"> </A> |
| 12013 | <H3>BUGS</H3> |
| 12014 | |
| 12015 | <P> |
| 12016 | |
| 12017 | It's too big and too slow. |
| 12018 | <P> |
| 12019 | |
| 12020 | There are some subtle differences between |
| 12021 | <B>bash</B> |
| 12022 | |
| 12023 | and traditional versions of |
| 12024 | <B>sh</B>, |
| 12025 | |
| 12026 | mostly because of the |
| 12027 | <FONT SIZE=-1><B>POSIX</B> |
| 12028 | |
| 12029 | </FONT> |
| 12030 | specification. |
| 12031 | <P> |
| 12032 | |
| 12033 | Aliases are confusing in some uses. |
| 12034 | <P> |
| 12035 | |
| 12036 | Shell builtin commands and functions are not stoppable/restartable. |
| 12037 | <P> |
| 12038 | |
| 12039 | Compound commands and command sequences of the form `a ; b ; c' |
| 12040 | are not handled gracefully when process suspension is attempted. |
| 12041 | When a process is stopped, the shell immediately executes the next |
| 12042 | command in the sequence. |
| 12043 | It suffices to place the sequence of commands between |
| 12044 | parentheses to force it into a subshell, which may be stopped as |
| 12045 | a unit. |
| 12046 | <P> |
| 12047 | |
| 12048 | Array variables may not (yet) be exported. |
| 12049 | <P> |
| 12050 | |
| 12051 | There may be only one active coprocess at a time. |
| 12052 | |
| 12053 | |
| 12054 | |
| 12055 | <HR> |
| 12056 | <TABLE WIDTH=100%> |
| 12057 | <TR> |
| 12058 | <TH ALIGN=LEFT width=33%>GNU Bash-4.0<TH ALIGN=CENTER width=33%>2008 December 29<TH ALIGN=RIGHT width=33%>BASH(1) |
| 12059 | </TR> |
| 12060 | </TABLE> |
| 12061 | <HR> |
| 12062 | <A NAME="index"> </A><H2>Index</H2> |
| 12063 | <DL> |
| 12064 | <DT><A HREF="#lbAB">NAME</A><DD> |
| 12065 | <DT><A HREF="#lbAC">SYNOPSIS</A><DD> |
| 12066 | <DT><A HREF="#lbAD">COPYRIGHT</A><DD> |
| 12067 | <DT><A HREF="#lbAE">DESCRIPTION</A><DD> |
| 12068 | <DT><A HREF="#lbAF">OPTIONS</A><DD> |
| 12069 | <DT><A HREF="#lbAG">ARGUMENTS</A><DD> |
| 12070 | <DT><A HREF="#lbAH">INVOCATION</A><DD> |
| 12071 | <DT><A HREF="#lbAI">DEFINITIONS</A><DD> |
| 12072 | <DT><A HREF="#lbAJ">RESERVED WORDS</A><DD> |
| 12073 | <DT><A HREF="#lbAK">SHELL GRAMMAR</A><DD> |
| 12074 | <DL> |
| 12075 | <DT><A HREF="#lbAL">Simple Commands</A><DD> |
| 12076 | <DT><A HREF="#lbAM">Pipelines</A><DD> |
| 12077 | <DT><A HREF="#lbAN">Lists</A><DD> |
| 12078 | <DT><A HREF="#lbAO">Compound Commands</A><DD> |
| 12079 | <DT><A HREF="#lbAP">Coprocesses</A><DD> |
| 12080 | <DT><A HREF="#lbAQ">Shell Function Definitions</A><DD> |
| 12081 | </DL> |
| 12082 | <DT><A HREF="#lbAR">COMMENTS</A><DD> |
| 12083 | <DT><A HREF="#lbAS">QUOTING</A><DD> |
| 12084 | <DT><A HREF="#lbAT">PARAMETERS</A><DD> |
| 12085 | <DL> |
| 12086 | <DT><A HREF="#lbAU">Positional Parameters</A><DD> |
| 12087 | <DT><A HREF="#lbAV">Special Parameters</A><DD> |
| 12088 | <DT><A HREF="#lbAW">Shell Variables</A><DD> |
| 12089 | <DT><A HREF="#lbAX">Arrays</A><DD> |
| 12090 | </DL> |
| 12091 | <DT><A HREF="#lbAY">EXPANSION</A><DD> |
| 12092 | <DL> |
| 12093 | <DT><A HREF="#lbAZ">Brace Expansion</A><DD> |
| 12094 | <DT><A HREF="#lbBA">Tilde Expansion</A><DD> |
| 12095 | <DT><A HREF="#lbBB">Parameter Expansion</A><DD> |
| 12096 | <DT><A HREF="#lbBC">Command Substitution</A><DD> |
| 12097 | <DT><A HREF="#lbBD">Arithmetic Expansion</A><DD> |
| 12098 | <DT><A HREF="#lbBE">Process Substitution</A><DD> |
| 12099 | <DT><A HREF="#lbBF">Word Splitting</A><DD> |
| 12100 | <DT><A HREF="#lbBG">Pathname Expansion</A><DD> |
| 12101 | <DT><A HREF="#lbBH">Quote Removal</A><DD> |
| 12102 | </DL> |
| 12103 | <DT><A HREF="#lbBI">REDIRECTION</A><DD> |
| 12104 | <DL> |
| 12105 | <DT><A HREF="#lbBJ">Redirecting Input</A><DD> |
| 12106 | <DT><A HREF="#lbBK">Redirecting Output</A><DD> |
| 12107 | <DT><A HREF="#lbBL">Appending Redirected Output</A><DD> |
| 12108 | <DT><A HREF="#lbBM">Redirecting Standard Output and Standard Error</A><DD> |
| 12109 | <DT><A HREF="#lbBN">Appending Standard Output and Standard Error</A><DD> |
| 12110 | <DT><A HREF="#lbBO">Here Documents</A><DD> |
| 12111 | <DT><A HREF="#lbBP">Here Strings</A><DD> |
| 12112 | <DT><A HREF="#lbBQ">Duplicating File Descriptors</A><DD> |
| 12113 | <DT><A HREF="#lbBR">Moving File Descriptors</A><DD> |
| 12114 | <DT><A HREF="#lbBS">Opening File Descriptors for Reading and Writing</A><DD> |
| 12115 | </DL> |
| 12116 | <DT><A HREF="#lbBT">ALIASES</A><DD> |
| 12117 | <DT><A HREF="#lbBU">FUNCTIONS</A><DD> |
| 12118 | <DT><A HREF="#lbBV">ARITHMETIC EVALUATION</A><DD> |
| 12119 | <DT><A HREF="#lbBW">CONDITIONAL EXPRESSIONS</A><DD> |
| 12120 | <DT><A HREF="#lbBX">SIMPLE COMMAND EXPANSION</A><DD> |
| 12121 | <DT><A HREF="#lbBY">COMMAND EXECUTION</A><DD> |
| 12122 | <DT><A HREF="#lbBZ">COMMAND EXECUTION ENVIRONMENT</A><DD> |
| 12123 | <DT><A HREF="#lbCA">ENVIRONMENT</A><DD> |
| 12124 | <DT><A HREF="#lbCB">EXIT STATUS</A><DD> |
| 12125 | <DT><A HREF="#lbCC">SIGNALS</A><DD> |
| 12126 | <DT><A HREF="#lbCD">JOB CONTROL</A><DD> |
| 12127 | <DT><A HREF="#lbCE">PROMPTING</A><DD> |
| 12128 | <DT><A HREF="#lbCF">READLINE</A><DD> |
| 12129 | <DL> |
| 12130 | <DT><A HREF="#lbCG">Readline Notation</A><DD> |
| 12131 | <DT><A HREF="#lbCH">Readline Initialization</A><DD> |
| 12132 | <DT><A HREF="#lbCI">Readline Key Bindings</A><DD> |
| 12133 | <DT><A HREF="#lbCJ">Readline Variables</A><DD> |
| 12134 | <DT><A HREF="#lbCK">Readline Conditional Constructs</A><DD> |
| 12135 | <DT><A HREF="#lbCL">Searching</A><DD> |
| 12136 | <DT><A HREF="#lbCM">Readline Command Names</A><DD> |
| 12137 | <DT><A HREF="#lbCN">Commands for Moving</A><DD> |
| 12138 | <DT><A HREF="#lbCO">Commands for Manipulating the History</A><DD> |
| 12139 | <DT><A HREF="#lbCP">Commands for Changing Text</A><DD> |
| 12140 | <DT><A HREF="#lbCQ">Killing and Yanking</A><DD> |
| 12141 | <DT><A HREF="#lbCR">Numeric Arguments</A><DD> |
| 12142 | <DT><A HREF="#lbCS">Completing</A><DD> |
| 12143 | <DT><A HREF="#lbCT">Keyboard Macros</A><DD> |
| 12144 | <DT><A HREF="#lbCU">Miscellaneous</A><DD> |
| 12145 | <DT><A HREF="#lbCV">Programmable Completion</A><DD> |
| 12146 | </DL> |
| 12147 | <DT><A HREF="#lbCW">HISTORY</A><DD> |
| 12148 | <DT><A HREF="#lbCX">HISTORY EXPANSION</A><DD> |
| 12149 | <DL> |
| 12150 | <DT><A HREF="#lbCY">Event Designators</A><DD> |
| 12151 | <DT><A HREF="#lbCZ">Word Designators</A><DD> |
| 12152 | <DT><A HREF="#lbDA">Modifiers</A><DD> |
| 12153 | </DL> |
| 12154 | <DT><A HREF="#lbDB">SHELL BUILTIN COMMANDS</A><DD> |
| 12155 | <DT><A HREF="#lbDC">RESTRICTED SHELL</A><DD> |
| 12156 | <DT><A HREF="#lbDD">SEE ALSO</A><DD> |
| 12157 | <DT><A HREF="#lbDE">FILES</A><DD> |
| 12158 | <DT><A HREF="#lbDF">AUTHORS</A><DD> |
| 12159 | <DT><A HREF="#lbDG">BUG REPORTS</A><DD> |
| 12160 | <DT><A HREF="#lbDH">BUGS</A><DD> |
| 12161 | </DL> |
| 12162 | <HR> |
| 12163 | This document was created by man2html from bash.1.<BR> |
| 12164 | Time: 05 February 2009 08:05:34 EST |
| 12165 | </BODY> |
| 12166 | </HTML> |