Mercurial > hg > octave-thorsten
annotate doc/interpreter/basics.txi @ 8653:2479ebf1c33f
doc/interpreter/system.txi: remove reference to 'eomdate'
| author | Soren Hauberg <hauberg@gmail.com> |
|---|---|
| date | Sun, 01 Feb 2009 16:30:29 +0100 |
| parents | fa78cb8d8a5c |
| children | 03b7f618ab3d |
| rev | line source |
|---|---|
| 7018 | 1 @c Copyright (C) 1996, 1997, 1999, 2000, 2001, 2002, 2003, 2005, 2006, |
| 2 @c 2007 John W. Eaton | |
| 3 @c | |
| 4 @c This file is part of Octave. | |
| 5 @c | |
| 6 @c Octave is free software; you can redistribute it and/or modify it | |
| 7 @c under the terms of the GNU General Public License as published by the | |
| 8 @c Free Software Foundation; either version 3 of the License, or (at | |
| 9 @c your option) any later version. | |
| 10 @c | |
| 11 @c Octave is distributed in the hope that it will be useful, but WITHOUT | |
| 12 @c ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 @c FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 @c for more details. | |
| 15 @c | |
| 16 @c You should have received a copy of the GNU General Public License | |
| 17 @c along with Octave; see the file COPYING. If not, see | |
| 18 @c <http://www.gnu.org/licenses/>. | |
| 3294 | 19 |
| 4167 | 20 @node Getting Started |
| 3294 | 21 @chapter Getting Started |
| 22 | |
| 23 This chapter explains some of Octave's basic features, including how to | |
| 24 start an Octave session, get help at the command prompt, edit the | |
| 25 command line, and write Octave programs that can be executed as commands | |
| 26 from your shell. | |
| 27 | |
| 28 @menu | |
| 6620 | 29 * Invoking Octave from the Command Line:: |
| 3294 | 30 * Quitting Octave:: |
| 31 * Getting Help:: | |
| 32 * Command Line Editing:: | |
| 33 * Errors:: | |
| 34 * Executable Octave Programs:: | |
| 35 * Comments:: | |
| 36 @end menu | |
| 37 | |
| 6620 | 38 @node Invoking Octave from the Command Line |
| 39 @section Invoking Octave from the Command Line | |
| 3294 | 40 |
| 41 Normally, Octave is used interactively by running the program | |
| 42 @samp{octave} without any arguments. Once started, Octave reads | |
| 43 commands from the terminal until you tell it to exit. | |
| 44 | |
| 45 You can also specify the name of a file on the command line, and Octave | |
| 46 will read and execute the commands from the named file and then exit | |
| 47 when it is finished. | |
| 48 | |
| 49 You can further control how Octave starts by using the command-line | |
| 50 options described in the next section, and Octave itself can remind you | |
| 51 of the options available. Type @samp{octave --help} to display all | |
| 52 available options and briefly describe their use (@samp{octave -h} is a | |
| 53 shorter equivalent). | |
| 54 | |
| 55 @menu | |
| 56 * Command Line Options:: | |
| 57 * Startup Files:: | |
| 58 @end menu | |
| 59 | |
| 4167 | 60 @node Command Line Options |
| 3294 | 61 @subsection Command Line Options |
| 62 @cindex Octave command options | |
| 63 @cindex command options | |
| 64 @cindex options, Octave command | |
| 65 | |
| 66 Here is a complete list of all the command line options that Octave | |
| 67 accepts. | |
| 68 | |
| 6620 | 69 |
| 3294 | 70 @table @code |
| 71 @item --debug | |
| 72 @itemx -d | |
| 73 @cindex @code{--debug} | |
| 74 @cindex @code{-d} | |
| 75 Enter parser debugging mode. Using this option will cause Octave's | |
| 76 parser to print a lot of information about the commands it reads, and is | |
| 77 probably only useful if you are actually trying to debug the parser. | |
| 78 | |
| 79 @item --echo-commands | |
| 80 @itemx -x | |
| 81 @cindex @code{--echo-commands} | |
| 82 @cindex @code{-x} | |
| 83 Echo commands as they are executed. | |
| 84 | |
| 5190 | 85 @item --eval @var{code} |
| 86 Evaluate @var{code} and exit when done unless @code{--persist} is also | |
| 87 specified. | |
| 88 | |
| 3294 | 89 @item --exec-path @var{path} |
| 90 @cindex @code{--exec-path @var{path}} | |
| 91 Specify the path to search for programs to run. The value of @var{path} | |
| 92 specified on the command line will override any value of | |
| 93 @code{OCTAVE_EXEC_PATH} found in the environment, but not any commands | |
| 94 in the system or user startup files that set the built-in variable | |
| 95 @code{EXEC_PATH}. | |
| 96 | |
| 97 @item --help | |
| 98 @itemx -h | |
| 99 @itemx -? | |
| 100 @cindex @code{--help} | |
| 101 @cindex @code{-h} | |
| 102 @cindex @code{-?} | |
| 103 Print short help message and exit. | |
| 104 | |
| 6620 | 105 @item --image-path @var{path} |
| 106 @cindex @code{--image-path @var{path}} | |
| 107 Specify the path to search for images. The value of @var{path} | |
| 108 specified on the command line will set the value of | |
| 109 @code{IMAGE_PATH} found in the environment. | |
| 110 | |
| 3294 | 111 @item --info-file @var{filename} |
| 112 @cindex @code{--info-file @var{filename}} | |
| 113 Specify the name of the info file to use. The value of @var{filename} | |
| 114 specified on the command line will override any value of | |
| 115 @code{OCTAVE_INFO_FILE} found in the environment, but not any commands | |
| 6653 | 116 in the system or user startup files that use the @code{info_file} |
| 6477 | 117 function. |
| 3294 | 118 |
| 119 @item --info-program @var{program} | |
| 120 @cindex @code{--info-program @var{program}} | |
| 121 Specify the name of the info program to use. The value of @var{program} | |
| 122 specified on the command line will override any value of | |
| 123 @code{OCTAVE_INFO_PROGRAM} found in the environment, but not any | |
| 6477 | 124 commands in the system or user startup files that use the |
| 125 @code{info_program} function. | |
| 3294 | 126 |
| 127 @item --interactive | |
| 128 @itemx -i | |
| 129 @cindex @code{--interactive} | |
| 130 @cindex @code{-i} | |
| 131 Force interactive behavior. This can be useful for running Octave via a | |
| 132 remote shell command or inside an Emacs shell buffer. For another way | |
| 133 to run Octave within Emacs, see @ref{Emacs}. | |
| 134 | |
| 3428 | 135 @item --no-history |
| 136 @itemx -H | |
| 137 Disable command-line history. | |
| 138 | |
| 3294 | 139 @item --no-init-file |
| 140 @cindex @code{--no-init-file} | |
| 141 Don't read the @file{~/.octaverc} or @file{.octaverc} files. | |
| 142 | |
| 143 @item --no-line-editing | |
| 144 @cindex @code{--no-line-editing} | |
| 145 Disable command-line editing. | |
| 146 | |
| 147 @item --no-site-file | |
| 148 @cindex @code{--no-site-file} | |
| 149 Don't read the site-wide @file{octaverc} file. | |
| 150 | |
| 151 @item --norc | |
| 152 @itemx -f | |
| 153 @cindex @code{--norc} | |
| 154 @cindex @code{-f} | |
| 155 Don't read any of the system or user initialization files at startup. | |
| 156 This is equivalent to using both of the options @code{--no-init-file} | |
| 157 and @code{--no-site-file}. | |
| 158 | |
| 159 @item --path @var{path} | |
| 160 @itemx -p @var{path} | |
| 161 @cindex @code{--path @var{path}} | |
| 162 @cindex @code{-p @var{path}} | |
| 163 Specify the path to search for function files. The value of @var{path} | |
| 164 specified on the command line will override any value of | |
| 165 @code{OCTAVE_PATH} found in the environment, but not any commands in the | |
| 6643 | 166 system or user startup files that set the internal load path through one |
| 167 of the path functions. | |
| 3294 | 168 |
| 5190 | 169 @item --persist |
| 170 Go to interactive mode after @code{--eval} or reading from a file | |
| 171 named on the command line. | |
| 172 | |
| 3294 | 173 @item --silent |
| 174 @itemx --quiet | |
| 175 @itemx -q | |
| 176 @cindex @code{--silent} | |
| 177 @cindex @code{--quiet} | |
| 178 @cindex @code{-q} | |
| 179 Don't print the usual greeting and version message at startup. | |
| 180 | |
| 181 @item --traditional | |
| 182 @itemx --braindead | |
| 183 @cindex @code{--traditional} | |
| 184 @cindex @code{--braindead} | |
| 6556 | 185 For compatibility with @sc{Matlab}, set initial values for |
| 186 user-preferences to the following values | |
| 3294 | 187 |
| 188 @example | |
| 4455 | 189 @group |
| 7031 | 190 PS1 = ">> " |
| 191 PS2 = "" | |
| 192 beep_on_error = true | |
| 193 crash_dumps_octave_core = false | |
| 194 default_save_options = "-mat-binary" | |
| 195 fixed_point_format = true | |
| 196 history_timestamp_format_string | |
| 197 = "%%-- %D %I:%M %p --%%" | |
| 198 page_screen_output = false | |
| 199 print_empty_dimensions = false | |
| 6556 | 200 @end group |
| 201 @end example | |
| 202 | |
| 203 @noindent | |
| 204 and disable the following warnings | |
| 205 @example | |
| 206 @group | |
| 7031 | 207 Octave:fopen-file-in-path |
| 208 Octave:function-name-clash | |
| 209 Octave:load-file-in-path | |
| 4455 | 210 @end group |
| 3294 | 211 @end example |
| 212 | |
| 213 @item --verbose | |
| 214 @itemx -V | |
| 215 @cindex @code{--verbose} | |
| 216 @cindex @code{-V} | |
| 217 Turn on verbose output. | |
| 218 | |
| 219 @item --version | |
| 220 @itemx -v | |
| 221 @cindex @code{--version} | |
| 222 @cindex @code{-v} | |
| 223 Print the program version number and exit. | |
| 224 | |
| 225 @item @var{file} | |
| 5190 | 226 Execute commands from @var{file}. Exit when done unless |
| 227 @code{--persist} is also specified. | |
| 3294 | 228 @end table |
| 229 | |
| 230 Octave also includes several built-in variables that contain information | |
| 231 about the command line, including the number of arguments and all of the | |
| 232 options. | |
| 233 | |
| 3332 | 234 @DOCSTRING(argv) |
| 3294 | 235 |
| 6550 | 236 @DOCSTRING(program_name) |
| 237 | |
| 3332 | 238 @DOCSTRING(program_invocation_name) |
| 3294 | 239 |
| 6479 | 240 Here is an example of using these functions to reproduce Octave's |
| 3294 | 241 command line. |
| 242 | |
| 243 @example | |
| 6479 | 244 printf ("%s", program_name ()); |
| 6620 | 245 arg_list = argv (); |
| 3294 | 246 for i = 1:nargin |
| 6479 | 247 printf (" %s", arg_list@{i@}); |
| 3294 | 248 endfor |
| 249 printf ("\n"); | |
| 250 @end example | |
| 251 | |
| 252 @noindent | |
| 3402 | 253 @xref{Index Expressions}, for an explanation of how to properly index |
| 254 arrays of strings and substrings in Octave, and @xref{Defining Functions}, | |
| 3294 | 255 for information about the variable @code{nargin}. |
| 256 | |
| 4167 | 257 @node Startup Files |
| 3294 | 258 @subsection Startup Files |
| 259 @cindex initialization | |
| 260 @cindex startup | |
| 261 | |
| 6620 | 262 When Octave starts, it looks for commands to execute from the files in |
| 263 the following list. These files may contain any valid Octave commands, | |
| 264 including function definitions. | |
| 3294 | 265 |
| 266 @cindex startup files | |
| 267 | |
| 268 @table @code | |
| 269 @item @var{octave-home}/share/octave/site/m/startup/octaverc | |
| 270 Where @var{octave-home} is the directory in which all of Octave is | |
| 271 installed (the default is @file{@value{OCTAVEHOME}}). This file is | |
| 272 provided so that changes to the default Octave environment can be made | |
| 273 globally for all users at your site for all versions of Octave you have | |
| 274 installed. Some care should be taken when making changes to this file, | |
| 275 since all users of Octave at your site will be affected. | |
| 276 | |
| 277 @item @var{octave-home}/share/octave/@var{version}/m/startup/octaverc | |
| 278 Where @var{octave-home} is the directory in which all of Octave is | |
| 279 installed (the default is @file{@value{OCTAVEHOME}}), and @var{version} | |
| 280 is the version number of Octave. This file is provided so that changes | |
| 281 to the default Octave environment can be made globally for all users for | |
| 282 a particular version of Octave. Some care should be taken when making | |
| 283 changes to this file, since all users of Octave at your site will be | |
| 284 affected. | |
| 285 | |
| 286 @item ~/.octaverc | |
| 287 @cindex @code{~/.octaverc} | |
| 288 This file is normally used to make personal changes to the default | |
| 289 Octave environment. | |
| 290 | |
| 291 @item .octaverc | |
| 292 @cindex @code{.octaverc} | |
| 293 This file can be used to make changes to the default Octave environment | |
| 294 for a particular project. Octave searches for this file in the current | |
| 295 directory after it reads @file{~/.octaverc}. Any use of the @code{cd} | |
| 296 command in the @file{~/.octaverc} file will affect the directory that | |
| 297 Octave searches for the file @file{.octaverc}. | |
| 298 | |
|
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|
299 If you start Octave in your home directory, commands from the file |
| 3294 | 300 @file{~/.octaverc} will only be executed once. |
| 301 @end table | |
| 302 | |
| 303 A message will be displayed as each of the startup files is read if you | |
| 304 invoke Octave with the @code{--verbose} option but without the | |
| 305 @code{--silent} option. | |
| 306 | |
| 4167 | 307 @node Quitting Octave |
| 3294 | 308 @section Quitting Octave |
| 309 @cindex exiting octave | |
| 310 @cindex quitting octave | |
| 311 | |
| 3332 | 312 @DOCSTRING(quit) |
| 3294 | 313 |
| 3332 | 314 @DOCSTRING(atexit) |
| 3294 | 315 |
| 4167 | 316 @node Getting Help |
| 3294 | 317 @section Commands for Getting Help |
| 318 @cindex on-line help | |
| 319 @cindex help, on-line | |
| 320 | |
| 321 The entire text of this manual is available from the Octave prompt | |
| 6620 | 322 via the command @kbd{doc}. In addition, the documentation for |
| 3294 | 323 individual user-written functions and variables is also available via |
| 324 the @kbd{help} command. This section describes the commands used for | |
| 325 reading the manual and the documentation strings for user-supplied | |
| 326 functions and variables. @xref{Function Files}, for more information | |
| 327 about how to document the functions you write. | |
| 328 | |
| 3332 | 329 @DOCSTRING(help) |
| 3294 | 330 |
| 6549 | 331 @DOCSTRING(doc) |
| 332 | |
| 333 @DOCSTRING(lookfor) | |
| 334 | |
| 6620 | 335 The following function can be used to change which programs are used |
| 336 for displaying the documentation, and where the documentation can be | |
| 337 found. | |
| 3294 | 338 |
| 6477 | 339 @DOCSTRING(info_file) |
| 3294 | 340 |
| 6477 | 341 @DOCSTRING(info_program) |
| 3294 | 342 |
| 6477 | 343 @DOCSTRING(makeinfo_program) |
| 3686 | 344 |
| 3332 | 345 @DOCSTRING(suppress_verbose_help_message) |
| 3294 | 346 |
| 4167 | 347 @node Command Line Editing |
| 3294 | 348 @section Command Line Editing |
| 349 @cindex command-line editing | |
| 350 @cindex editing the command line | |
| 351 | |
| 352 Octave uses the GNU readline library to provide an extensive set of | |
| 353 command-line editing and history features. Only the most common | |
| 354 features are described in this manual. Please see The GNU Readline | |
| 355 Library manual for more information. | |
| 356 | |
| 357 To insert printing characters (letters, digits, symbols, etc.), simply | |
| 358 type the character. Octave will insert the character at the cursor and | |
| 359 advance the cursor forward. | |
| 360 | |
| 361 Many of the command-line editing functions operate using control | |
| 362 characters. For example, the character @kbd{Control-a} moves the cursor | |
| 363 to the beginning of the line. To type @kbd{C-a}, hold down @key{CTRL} | |
| 364 and then press @key{a}. In the following sections, control characters | |
| 365 such as @kbd{Control-a} are written as @kbd{C-a}. | |
| 366 | |
| 367 Another set of command-line editing functions use Meta characters. On | |
| 368 some terminals, you type @kbd{M-u} by holding down @key{META} and | |
| 369 pressing @key{u}. If your terminal does not have a @key{META} key, you | |
| 7001 | 370 can still type Meta characters using two-character sequences starting |
| 3294 | 371 with @kbd{ESC}. Thus, to enter @kbd{M-u}, you could type |
| 372 @key{ESC}@key{u}. The @kbd{ESC} character sequences are also allowed on | |
| 373 terminals with real Meta keys. In the following sections, Meta | |
| 374 characters such as @kbd{Meta-u} are written as @kbd{M-u}. | |
| 375 | |
| 3428 | 376 |
| 3294 | 377 @menu |
| 378 * Cursor Motion:: | |
| 379 * Killing and Yanking:: | |
| 380 * Commands For Text:: | |
| 381 * Commands For Completion:: | |
| 382 * Commands For History:: | |
| 3439 | 383 * Customizing readline:: |
| 3294 | 384 * Customizing the Prompt:: |
| 385 * Diary and Echo Commands:: | |
| 386 @end menu | |
| 387 | |
| 4167 | 388 @node Cursor Motion |
| 3294 | 389 @subsection Cursor Motion |
| 390 | |
| 391 The following commands allow you to position the cursor. | |
| 392 | |
| 393 @table @kbd | |
| 394 @item C-b | |
| 395 Move back one character. | |
| 396 | |
| 397 @item C-f | |
| 398 Move forward one character. | |
| 399 | |
| 400 @item @key{DEL} | |
| 401 Delete the character to the left of the cursor. | |
| 402 | |
| 403 @item C-d | |
| 404 Delete the character underneath the cursor. | |
| 405 | |
| 406 @item M-f | |
| 407 Move forward a word. | |
| 408 | |
| 409 @item M-b | |
| 410 Move backward a word. | |
| 411 | |
| 412 @item C-a | |
| 413 Move to the start of the line. | |
| 414 | |
| 415 @item C-e | |
| 416 Move to the end of the line. | |
| 417 | |
| 418 @item C-l | |
| 419 Clear the screen, reprinting the current line at the top. | |
| 420 | |
| 421 @item C-_ | |
| 422 @itemx C-/ | |
| 423 Undo the last thing that you did. You can undo all the way back to an | |
| 424 empty line. | |
| 425 | |
| 426 @item M-r | |
| 427 Undo all changes made to this line. This is like typing the `undo' | |
| 428 command enough times to get back to the beginning. | |
| 429 @end table | |
| 430 | |
| 431 The above table describes the most basic possible keystrokes that you need | |
| 432 in order to do editing of the input line. On most terminals, you can | |
| 433 also use the arrow keys in place of @kbd{C-f} and @kbd{C-b} to move | |
| 434 forward and backward. | |
| 435 | |
| 436 Notice how @kbd{C-f} moves forward a character, while @kbd{M-f} moves | |
| 437 forward a word. It is a loose convention that control keystrokes | |
| 438 operate on characters while meta keystrokes operate on words. | |
| 439 | |
| 440 @cindex clearing the screen | |
| 441 | |
| 6620 | 442 The function @code{clc} will allow you to clear the screen from within |
| 443 Octave programs. | |
| 444 | |
| 445 @ifinfo | |
| 3332 | 446 @DOCSTRING(clc) |
| 6620 | 447 @end ifinfo |
| 3294 | 448 |
| 4167 | 449 @node Killing and Yanking |
| 3294 | 450 @subsection Killing and Yanking |
| 451 | |
| 452 @dfn{Killing} text means to delete the text from the line, but to save | |
| 453 it away for later use, usually by @dfn{yanking} it back into the line. | |
| 454 If the description for a command says that it `kills' text, then you can | |
| 455 be sure that you can get the text back in a different (or the same) | |
| 456 place later. | |
| 457 | |
| 458 Here is the list of commands for killing text. | |
| 459 | |
| 460 @table @kbd | |
| 461 @item C-k | |
| 462 Kill the text from the current cursor position to the end of the line. | |
| 463 | |
| 464 @item M-d | |
| 465 Kill from the cursor to the end of the current word, or if between | |
| 466 words, to the end of the next word. | |
| 467 | |
| 468 @item M-@key{DEL} | |
| 469 Kill from the cursor to the start of the previous word, or if between | |
| 470 words, to the start of the previous word. | |
| 471 | |
| 472 @item C-w | |
| 473 Kill from the cursor to the previous whitespace. This is different than | |
| 474 @kbd{M-@key{DEL}} because the word boundaries differ. | |
| 475 @end table | |
| 476 | |
| 477 And, here is how to @dfn{yank} the text back into the line. Yanking | |
| 478 means to copy the most-recently-killed text from the kill buffer. | |
| 479 | |
| 480 @table @kbd | |
| 481 @item C-y | |
| 482 Yank the most recently killed text back into the buffer at the cursor. | |
| 483 | |
| 484 @item M-y | |
| 485 Rotate the kill-ring, and yank the new top. You can only do this if | |
| 486 the prior command is @kbd{C-y} or @kbd{M-y}. | |
| 487 @end table | |
| 488 | |
| 489 When you use a kill command, the text is saved in a @dfn{kill-ring}. | |
| 490 Any number of consecutive kills save all of the killed text together, so | |
| 491 that when you yank it back, you get it in one clean sweep. The kill | |
| 492 ring is not line specific; the text that you killed on a previously | |
| 493 typed line is available to be yanked back later, when you are typing | |
| 494 another line. | |
| 495 | |
| 4167 | 496 @node Commands For Text |
| 3294 | 497 @subsection Commands For Changing Text |
| 498 | |
| 499 The following commands can be used for entering characters that would | |
| 500 otherwise have a special meaning (e.g., @kbd{TAB}, @kbd{C-q}, etc.), or | |
| 501 for quickly correcting typing mistakes. | |
| 502 | |
| 503 @table @kbd | |
| 504 @item C-q | |
| 505 @itemx C-v | |
| 506 Add the next character that you type to the line verbatim. This is | |
| 507 how to insert things like @kbd{C-q} for example. | |
| 508 | |
| 509 @item M-@key{TAB} | |
| 510 Insert a tab character. | |
| 511 | |
| 512 @item C-t | |
| 513 Drag the character before the cursor forward over the character at the | |
| 514 cursor, also moving the cursor forward. If the cursor is at the end of | |
| 515 the line, then transpose the two characters before it. | |
| 516 | |
| 517 @item M-t | |
| 518 Drag the word behind the cursor past the word in front of the cursor | |
| 519 moving the cursor over that word as well. | |
| 520 | |
| 521 @item M-u | |
| 522 Uppercase the characters following the cursor to the end of the current | |
| 523 (or following) word, moving the cursor to the end of the word. | |
| 524 | |
| 525 @item M-l | |
| 6620 | 526 Lowercase the characters following the cursor to the end of the current |
| 3294 | 527 (or following) word, moving the cursor to the end of the word. |
| 528 | |
| 529 @item M-c | |
| 530 Uppercase the character following the cursor (or the beginning of the | |
| 531 next word if the cursor is between words), moving the cursor to the end | |
| 532 of the word. | |
| 533 @end table | |
| 534 | |
| 4167 | 535 @node Commands For Completion |
| 3294 | 536 @subsection Letting Readline Type For You |
| 537 @cindex command completion | |
| 538 | |
| 539 The following commands allow Octave to complete command and variable | |
| 540 names for you. | |
| 541 | |
| 542 @table @kbd | |
| 543 @item @key{TAB} | |
| 544 Attempt to do completion on the text before the cursor. Octave can | |
| 545 complete the names of commands and variables. | |
| 546 | |
| 547 @item M-? | |
| 548 List the possible completions of the text before the cursor. | |
| 549 @end table | |
| 550 | |
| 3332 | 551 @DOCSTRING(completion_append_char) |
| 3294 | 552 |
| 3332 | 553 @DOCSTRING(completion_matches) |
| 3294 | 554 |
| 4167 | 555 @node Commands For History |
| 3294 | 556 @subsection Commands For Manipulating The History |
| 557 @cindex command history | |
| 558 @cindex input history | |
| 559 @cindex history of commands | |
| 560 | |
| 561 Octave normally keeps track of the commands you type so that you can | |
| 562 recall previous commands to edit or execute them again. When you exit | |
| 563 Octave, the most recent commands you have typed, up to the number | |
| 564 specified by the variable @code{history_size}, are saved in a file. | |
| 565 When Octave starts, it loads an initial list of commands from the file | |
| 566 named by the variable @code{history_file}. | |
| 567 | |
| 568 Here are the commands for simple browsing and searching the history | |
| 569 list. | |
| 570 | |
| 571 @table @kbd | |
| 572 @item @key{LFD} | |
| 573 @itemx @key{RET} | |
| 574 Accept the line regardless of where the cursor is. If this line is | |
| 575 non-empty, add it to the history list. If this line was a history | |
| 576 line, then restore the history line to its original state. | |
| 577 | |
| 578 @item C-p | |
| 579 Move `up' through the history list. | |
| 580 | |
| 581 @item C-n | |
| 582 Move `down' through the history list. | |
| 583 | |
| 584 @item M-< | |
| 585 Move to the first line in the history. | |
| 586 | |
| 587 @item M-> | |
| 588 Move to the end of the input history, i.e., the line you are entering! | |
| 589 | |
| 590 @item C-r | |
| 591 Search backward starting at the current line and moving `up' through | |
| 592 the history as necessary. This is an incremental search. | |
| 593 | |
| 594 @item C-s | |
| 595 Search forward starting at the current line and moving `down' through | |
| 596 the history as necessary. | |
| 597 @end table | |
| 598 | |
| 599 On most terminals, you can also use the arrow keys in place of @kbd{C-p} | |
| 600 and @kbd{C-n} to move through the history list. | |
| 601 | |
| 602 In addition to the keyboard commands for moving through the history | |
| 603 list, Octave provides three functions for viewing, editing, and | |
| 604 re-running chunks of commands from the history list. | |
| 605 | |
| 3332 | 606 @DOCSTRING(history) |
| 3294 | 607 |
| 3332 | 608 @DOCSTRING(edit_history) |
| 3294 | 609 |
| 3332 | 610 @DOCSTRING(run_history) |
| 3294 | 611 |
| 6620 | 612 Octave also allows you customize the details of how and where the history |
| 613 is saved. | |
| 3294 | 614 |
| 3332 | 615 @DOCSTRING(history_file) |
| 3294 | 616 |
| 3332 | 617 @DOCSTRING(history_size) |
| 3294 | 618 |
| 3332 | 619 @DOCSTRING(saving_history) |
| 3294 | 620 |
| 6550 | 621 @DOCSTRING(history_timestamp_format_string) |
| 622 | |
| 6620 | 623 @DOCSTRING(EDITOR) |
| 624 | |
| 4167 | 625 @node Customizing readline |
| 3428 | 626 @subsection Customizing @code{readline} |
| 627 | |
| 6620 | 628 As mentioned earlier Octave uses the GNU readline library for |
| 629 command-line editing and history features. It is possible to | |
| 630 customize how readline works through a configuration file. | |
| 631 | |
| 5775 | 632 @c FIXME -- need a brief description of the ~/.inputrc file here. |
| 3428 | 633 |
| 3439 | 634 @DOCSTRING(read_readline_init_file) |
| 3428 | 635 |
| 4167 | 636 @node Customizing the Prompt |
| 3294 | 637 @subsection Customizing the Prompt |
| 638 @cindex prompt customization | |
| 639 @cindex customizing the prompt | |
| 640 | |
| 641 The following variables are available for customizing the appearance of | |
| 642 the command-line prompts. Octave allows the prompt to be customized by | |
| 643 inserting a number of backslash-escaped special characters that are | |
| 644 decoded as follows: | |
| 645 | |
| 646 @table @samp | |
| 647 @item \t | |
| 648 The time. | |
| 649 | |
| 650 @item \d | |
| 651 The date. | |
| 652 | |
| 653 @item \n | |
| 654 Begins a new line by printing the equivalent of a carriage return | |
| 655 followed by a line feed. | |
| 656 | |
| 657 @item \s | |
| 658 The name of the program (usually just @samp{octave}). | |
| 659 | |
| 660 @item \w | |
| 661 The current working directory. | |
| 662 | |
| 663 @item \W | |
| 664 The basename of the current working directory. | |
| 665 | |
| 666 @item \u | |
| 667 The username of the current user. | |
| 668 | |
| 669 @item \h | |
| 670 The hostname, up to the first `.'. | |
| 671 | |
| 672 @item \H | |
| 673 The hostname. | |
| 674 | |
| 675 @item \# | |
| 676 The command number of this command, counting from when Octave starts. | |
| 677 | |
| 678 @item \! | |
| 679 The history number of this command. This differs from @samp{\#} by the | |
| 680 number of commands in the history list when Octave starts. | |
| 681 | |
| 682 @item \$ | |
| 683 If the effective UID is 0, a @samp{#}, otherwise a @samp{$}. | |
| 684 | |
| 685 @item \nnn | |
| 686 The character whose character code in octal is @var{nnn}. | |
| 687 | |
| 688 @item \\ | |
| 689 A backslash. | |
| 690 @end table | |
| 691 | |
| 3332 | 692 @DOCSTRING(PS1) |
| 3294 | 693 |
| 3332 | 694 @DOCSTRING(PS2) |
| 3294 | 695 |
| 3332 | 696 @DOCSTRING(PS4) |
| 3294 | 697 |
| 4167 | 698 @node Diary and Echo Commands |
| 3294 | 699 @subsection Diary and Echo Commands |
| 700 @cindex diary of commands and output | |
| 6939 | 701 @cindex command and output logs |
| 3294 | 702 @cindex logging commands and output |
| 703 @cindex echoing executing commands | |
| 704 @cindex command echoing | |
| 705 | |
| 706 Octave's diary feature allows you to keep a log of all or part of an | |
| 707 interactive session by recording the input you type and the output that | |
| 708 Octave produces in a separate file. | |
| 709 | |
| 3332 | 710 @DOCSTRING(diary) |
| 3294 | 711 |
| 712 Sometimes it is useful to see the commands in a function or script as | |
| 713 they are being evaluated. This can be especially helpful for debugging | |
| 714 some kinds of problems. | |
| 715 | |
| 3332 | 716 @DOCSTRING(echo) |
| 3294 | 717 |
| 3332 | 718 @DOCSTRING(echo_executing_commands) |
| 3294 | 719 |
| 4167 | 720 @node Errors |
| 3294 | 721 @section How Octave Reports Errors |
| 722 @cindex error messages | |
| 723 @cindex messages, error | |
| 724 | |
| 725 Octave reports two kinds of errors for invalid programs. | |
| 726 | |
| 727 A @dfn{parse error} occurs if Octave cannot understand something you | |
| 728 have typed. For example, if you misspell a keyword, | |
| 729 | |
| 730 @example | |
| 731 octave:13> functon y = f (x) y = x^2; endfunction | |
| 732 @end example | |
| 733 | |
| 734 @noindent | |
| 735 Octave will respond immediately with a message like this: | |
| 736 | |
| 737 @example | |
| 738 parse error: | |
| 739 | |
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740 syntax error |
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741 |
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742 >>> functon y = f (x) y = x^2; endfunction |
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743 ^ |
| 3294 | 744 @end example |
| 745 | |
| 746 @noindent | |
| 747 For most parse errors, Octave uses a caret (@samp{^}) to mark the point | |
| 748 on the line where it was unable to make sense of your input. In this | |
| 749 case, Octave generated an error message because the keyword | |
| 750 @code{function} was misspelled. Instead of seeing @samp{function f}, | |
| 751 Octave saw two consecutive variable names, which is invalid in this | |
| 752 context. It marked the error at @code{y} because the first name by | |
| 753 itself was accepted as valid input. | |
| 754 | |
| 755 Another class of error message occurs at evaluation time. These | |
| 756 errors are called @dfn{run-time errors}, or sometimes | |
| 757 @dfn{evaluation errors} because they occur when your program is being | |
| 758 @dfn{run}, or @dfn{evaluated}. For example, if after correcting the | |
| 759 mistake in the previous function definition, you type | |
| 760 | |
| 761 @example | |
| 762 octave:13> f () | |
| 763 @end example | |
| 764 | |
| 765 @noindent | |
| 766 Octave will respond with | |
| 767 | |
| 7031 | 768 @c Using 'smallexample' to make text fit on page when creating smallbook. |
| 769 @smallexample | |
| 3294 | 770 @group |
| 771 error: `x' undefined near line 1 column 24 | |
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772 error: called from: |
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773 error: f at line 1, column 22 |
| 3294 | 774 @end group |
| 7031 | 775 @end smallexample |
| 3294 | 776 |
| 6620 | 777 @noindent |
| 3294 | 778 This error message has several parts, and gives you quite a bit of |
| 779 information to help you locate the source of the error. The messages | |
| 780 are generated from the point of the innermost error, and provide a | |
| 781 traceback of enclosing expressions and function calls. | |
| 782 | |
| 783 In the example above, the first line indicates that a variable named | |
| 784 @samp{x} was found to be undefined near line 1 and column 24 of some | |
| 785 function or expression. For errors occurring within functions, lines | |
| 786 are counted from the beginning of the file containing the function | |
| 787 definition. For errors occurring at the top level, the line number | |
| 788 indicates the input line number, which is usually displayed in the | |
| 789 prompt string. | |
| 790 | |
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791 The second and third lines in the error message indicates that the error occurred |
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792 within the function @code{f}. If the function @code{f} had been called from |
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793 another function, for example, @code{g}, the list of errors would have ended with |
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794 one more line: |
| 3294 | 795 |
| 796 @example | |
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797 error: g at line 1, column 17 |
| 3294 | 798 @end example |
| 799 | |
| 800 These lists of function calls usually make it fairly easy to trace the | |
| 801 path your program took before the error occurred, and to correct the | |
| 802 error before trying again. | |
| 803 | |
| 4167 | 804 @node Executable Octave Programs |
| 3294 | 805 @section Executable Octave Programs |
| 806 @cindex executable scripts | |
| 807 @cindex scripts | |
| 808 @cindex self contained programs | |
| 809 @cindex program, self contained | |
| 810 @cindex @samp{#!} | |
| 811 | |
| 812 Once you have learned Octave, you may want to write self-contained | |
| 813 Octave scripts, using the @samp{#!} script mechanism. You can do this | |
| 814 on GNU systems and on many Unix systems @footnote{The @samp{#!} | |
| 815 mechanism works on Unix systems derived from Berkeley Unix, System V | |
| 6481 | 816 Release 4, and some System V Release 3 systems.}. |
| 817 | |
| 818 Self-contained Octave scripts are useful when you want to write a | |
| 819 program which users can invoke without knowing that the program is | |
| 820 written in the Octave language. | |
| 3294 | 821 |
| 822 For example, you could create a text file named @file{hello}, containing | |
| 823 the following lines: | |
| 824 | |
| 825 @example | |
| 826 @group | |
| 827 #! @var{octave-interpreter-name} -qf | |
| 828 # a sample Octave program | |
| 829 printf ("Hello, world!\n"); | |
| 830 @end group | |
| 831 @end example | |
| 832 | |
| 833 @noindent | |
| 834 (where @var{octave-interpreter-name} should be replaced with the full | |
| 6481 | 835 file name for your Octave binary). Note that this will only work if |
| 836 @samp{#!} appears at the very beginning of the file. After making this | |
| 837 file executable | |
| 3294 | 838 (with the @code{chmod} command), you can simply type: |
| 839 | |
| 840 @example | |
| 841 hello | |
| 842 @end example | |
| 843 | |
| 844 @noindent | |
| 845 at the shell, and the system will arrange to run Octave as if you had | |
| 846 typed: | |
| 847 | |
| 848 @example | |
| 849 octave hello | |
| 850 @end example | |
| 851 | |
| 852 The line beginning with @samp{#!} lists the full file name of an | |
| 853 interpreter to be run, and an optional initial command line argument to | |
| 854 pass to that interpreter. The operating system then runs the | |
| 855 interpreter with the given argument and the full argument list of the | |
| 856 executed program. The first argument in the list is the full file name | |
| 857 of the Octave program. The rest of the argument list will either be | |
| 858 options to Octave, or data files, or both. The @samp{-qf} option is | |
| 859 usually specified in stand-alone Octave programs to prevent them from | |
| 860 printing the normal startup message, and to keep them from behaving | |
| 861 differently depending on the contents of a particular user's | |
| 6620 | 862 @file{~/.octaverc} file. @xref{Invoking Octave from the Command Line}. |
| 6481 | 863 |
| 864 Note that some operating systems may place a limit on the number of | |
| 865 characters that are recognized after @samp{#!}. Also, the various | |
| 866 shells/systems parse differently the arguments appearing in a @samp{#!} | |
| 867 line. The majority of them group together all the arguments in a string | |
| 6939 | 868 and pass it to the interpreter as a single argument. In this case, the |
| 6481 | 869 following script: |
| 870 | |
| 871 @example | |
| 872 @group | |
| 873 #! @var{octave-interpreter-name} -q -f # comment | |
| 874 @end group | |
| 875 @end example | |
| 876 | |
| 877 @noindent | |
| 878 is equivalent to type at the command line: | |
| 3294 | 879 |
| 6481 | 880 @example |
| 881 @group | |
| 882 octave "-q -f # comment" | |
| 883 @end group | |
| 884 @end example | |
| 3294 | 885 |
| 6481 | 886 @noindent |
| 887 which would obviously produce an error message. Unfortunately, it is | |
| 888 impossible for Octave to know whether it has been called from the command | |
| 889 line or from a @samp{#!} script, so some care is needed when using the | |
| 890 @samp{#!} mechanism. | |
| 891 | |
| 892 Note that when Octave is started from an executable script, the built-in | |
| 893 function @code{argv} returns a cell array containing the command line | |
| 894 arguments passed to an executable Octave script, not the arguments | |
| 895 passed to the Octave interpreter on the @samp{#!} line of the script. | |
| 896 For example, the following program will reproduce the command line that | |
| 897 is used to execute script, not @samp{-qf}. | |
| 3294 | 898 |
| 899 @example | |
| 900 @group | |
| 901 #! /bin/octave -qf | |
| 6479 | 902 printf ("%s", program_name ()); |
| 6620 | 903 arg_list = argv (); |
| 3294 | 904 for i = 1:nargin |
| 6479 | 905 printf (" %s", arg_list@{i@}); |
| 3294 | 906 endfor |
| 907 printf ("\n"); | |
| 908 @end group | |
| 909 @end example | |
| 910 | |
| 4167 | 911 @node Comments |
| 3294 | 912 @section Comments in Octave Programs |
| 913 @cindex @samp{#} | |
| 914 @cindex @samp{%} | |
| 915 @cindex comments | |
| 916 @cindex use of comments | |
| 917 @cindex documenting Octave programs | |
| 918 @cindex programs | |
| 919 | |
| 920 A @dfn{comment} is some text that is included in a program for the sake | |
| 921 of human readers, and that is not really part of the program. Comments | |
| 922 can explain what the program does, and how it works. Nearly all | |
| 923 programming languages have provisions for comments, because programs are | |
| 924 typically hard to understand without them. | |
| 925 | |
| 926 In the Octave language, a comment starts with either the sharp sign | |
| 927 character, @samp{#}, or the percent symbol @samp{%} and continues to the | |
| 928 end of the line. The Octave interpreter ignores the rest of a | |
| 929 line following a sharp sign or percent symbol. For example, we could | |
| 930 have put the following into the function @code{f}: | |
| 931 | |
| 932 @example | |
| 933 @group | |
| 934 function xdot = f (x, t) | |
| 935 | |
| 936 # usage: f (x, t) | |
| 937 # | |
| 938 # This function defines the right hand | |
| 939 # side functions for a set of nonlinear | |
| 940 # differential equations. | |
| 941 | |
| 942 r = 0.25; | |
| 943 @dots{} | |
| 944 endfunction | |
| 945 @end group | |
| 946 @end example | |
| 947 | |
| 948 The @code{help} command (@pxref{Getting Help}) is able to find the first | |
| 949 block of comments in a function (even those that are composed directly | |
| 950 on the command line). This means that users of Octave can use the same | |
| 951 commands to get help for built-in functions, and for functions that you | |
| 952 have defined. For example, after defining the function @code{f} above, | |
| 953 the command @kbd{help f} produces the output | |
| 954 | |
| 955 @example | |
| 956 @group | |
| 957 usage: f (x, t) | |
| 958 | |
| 959 This function defines the right hand | |
| 960 side functions for a set of nonlinear | |
| 961 differential equations. | |
| 962 @end group | |
| 963 @end example | |
| 964 | |
| 965 Although it is possible to put comment lines into keyboard-composed | |
| 966 throw-away Octave programs, it usually isn't very useful, because the | |
| 967 purpose of a comment is to help you or another person understand the | |
| 968 program at a later time. | |
| 969 |