428
+ − 1 @c -*-texinfo-*-
+ − 2 @c This is part of the XEmacs Lisp Reference Manual.
444
+ − 3 @c Copyright (C) 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc.
428
+ − 4 @c See the file lispref.texi for copying conditions.
+ − 5 @setfilename ../../info/os.info
+ − 6 @node System Interface, X-Windows, Processes, Top
+ − 7 @chapter Operating System Interface
+ − 8
+ − 9 This chapter is about starting and getting out of Emacs, access to
+ − 10 values in the operating system environment, and terminal input, output,
+ − 11 and flow control.
+ − 12
+ − 13 @xref{Building XEmacs}, for related information. See also
+ − 14 @ref{Display}, for additional operating system status information
+ − 15 pertaining to the terminal and the screen.
+ − 16
+ − 17 @menu
+ − 18 * Starting Up:: Customizing XEmacs start-up processing.
+ − 19 * Getting Out:: How exiting works (permanent or temporary).
+ − 20 * System Environment:: Distinguish the name and kind of system.
+ − 21 * User Identification:: Finding the name and user id of the user.
+ − 22 * Time of Day:: Getting the current time.
+ − 23 * Time Conversion:: Converting a time from numeric form to a string, or
+ − 24 to calendrical data (or vice versa).
+ − 25 * Timers:: Setting a timer to call a function at a certain time.
+ − 26 * Terminal Input:: Recording terminal input for debugging.
+ − 27 * Terminal Output:: Recording terminal output for debugging.
+ − 28 * Flow Control:: How to turn output flow control on or off.
+ − 29 * Batch Mode:: Running XEmacs without terminal interaction.
+ − 30 @end menu
+ − 31 @ignore
+ − 32 * Special Keysyms:: Defining system-specific key symbols for X windows.
+ − 33 @end ignore
+ − 34
+ − 35 @node Starting Up
+ − 36 @section Starting Up XEmacs
+ − 37
+ − 38 This section describes what XEmacs does when it is started, and how you
+ − 39 can customize these actions.
+ − 40
+ − 41 @menu
+ − 42 * Start-up Summary:: Sequence of actions XEmacs performs at start-up.
+ − 43 * Init File:: Details on reading the init file (@file{.emacs}).
+ − 44 * Terminal-Specific:: How the terminal-specific Lisp file is read.
+ − 45 * Command Line Arguments:: How command line arguments are processed,
+ − 46 and how you can customize them.
+ − 47 @end menu
+ − 48
+ − 49 @node Start-up Summary
+ − 50 @subsection Summary: Sequence of Actions at Start Up
+ − 51 @cindex initialization
+ − 52 @cindex start up of XEmacs
+ − 53 @cindex @file{startup.el}
+ − 54
+ − 55 The order of operations performed (in @file{startup.el}) by XEmacs when
+ − 56 it is started up is as follows:
+ − 57
+ − 58 @enumerate
+ − 59 @item
+ − 60 It loads the initialization library for the window system, if you are
+ − 61 using a window system. This library's name is
+ − 62 @file{term/@var{windowsystem}-win.el}.
+ − 63
+ − 64 @item
+ − 65 It processes the initial options. (Some of them are handled
+ − 66 even earlier than this.)
+ − 67
+ − 68 @item
+ − 69 It initializes the X window frame and faces, if appropriate.
+ − 70
+ − 71 @item
+ − 72 It runs the normal hook @code{before-init-hook}.
+ − 73
+ − 74 @item
+ − 75 It loads the library @file{site-start}, unless the option
+ − 76 @samp{-no-site-file} was specified. The library's file name is usually
+ − 77 @file{site-start.el}.
+ − 78 @cindex @file{site-start.el}
+ − 79
444
+ − 80 @item
428
+ − 81 It loads the file @file{~/.emacs} unless @samp{-q} was specified on
+ − 82 the command line. (This is not done in @samp{-batch} mode.) The @samp{-u}
+ − 83 option can specify the user name whose home directory should be used
+ − 84 instead of @file{~}.
+ − 85
444
+ − 86 @item
428
+ − 87 It loads the library @file{default} unless @code{inhibit-default-init}
+ − 88 is non-@code{nil}. (This is not done in @samp{-batch} mode or if
+ − 89 @samp{-q} was specified on the command line.) The library's file name
+ − 90 is usually @file{default.el}.
+ − 91 @cindex @file{default.el}
+ − 92
+ − 93 @item
+ − 94 It runs the normal hook @code{after-init-hook}.
+ − 95
+ − 96 @item
+ − 97 It sets the major mode according to @code{initial-major-mode}, provided
+ − 98 the buffer @samp{*scratch*} is still current and still in Fundamental
+ − 99 mode.
+ − 100
444
+ − 101 @item
428
+ − 102 It loads the terminal-specific Lisp file, if any, except when in batch
+ − 103 mode or using a window system.
+ − 104
+ − 105 @item
+ − 106 It displays the initial echo area message, unless you have suppressed
+ − 107 that with @code{inhibit-startup-echo-area-message}.
+ − 108
444
+ − 109 @item
428
+ − 110 It processes the action arguments from the command line.
+ − 111
444
+ − 112 @item
428
+ − 113 It runs @code{term-setup-hook}.
+ − 114
+ − 115 @item
+ − 116 It calls @code{frame-notice-user-settings}, which modifies the
+ − 117 parameters of the selected frame according to whatever the init files
+ − 118 specify.
+ − 119
444
+ − 120 @item
428
+ − 121 It runs @code{window-setup-hook}. @xref{Terminal-Specific}.
+ − 122
444
+ − 123 @item
428
+ − 124 It displays copyleft, nonwarranty, and basic use information, provided
+ − 125 there were no remaining command line arguments (a few steps above) and
+ − 126 the value of @code{inhibit-startup-message} is @code{nil}.
+ − 127 @end enumerate
+ − 128
+ − 129 @defopt inhibit-startup-message
+ − 130 This variable inhibits the initial startup messages (the nonwarranty,
+ − 131 etc.). If it is non-@code{nil}, then the messages are not printed.
+ − 132
+ − 133 This variable exists so you can set it in your personal init file, once
+ − 134 you are familiar with the contents of the startup message. Do not set
+ − 135 this variable in the init file of a new user, or in a way that affects
+ − 136 more than one user, because that would prevent new users from receiving
+ − 137 the information they are supposed to see.
+ − 138 @end defopt
+ − 139
+ − 140 @defopt inhibit-startup-echo-area-message
+ − 141 This variable controls the display of the startup echo area message.
+ − 142 You can suppress the startup echo area message by adding text with this
+ − 143 form to your @file{.emacs} file:
+ − 144
+ − 145 @example
+ − 146 (setq inhibit-startup-echo-area-message
+ − 147 "@var{your-login-name}")
+ − 148 @end example
+ − 149
+ − 150 Simply setting @code{inhibit-startup-echo-area-message} to your login
+ − 151 name is not sufficient to inhibit the message; Emacs explicitly checks
+ − 152 whether @file{.emacs} contains an expression as shown above. Your login
+ − 153 name must appear in the expression as a Lisp string constant.
+ − 154
+ − 155 This way, you can easily inhibit the message for yourself if you wish,
+ − 156 but thoughtless copying of your @file{.emacs} file will not inhibit the
+ − 157 message for someone else.
+ − 158 @end defopt
+ − 159
+ − 160 @node Init File
+ − 161 @subsection The Init File: @file{.emacs}
+ − 162 @cindex init file
+ − 163 @cindex @file{.emacs}
+ − 164
+ − 165 When you start XEmacs, it normally attempts to load the file
+ − 166 @file{.emacs} from your home directory. This file, if it exists, must
+ − 167 contain Lisp code. It is called your @dfn{init file}. The command line
+ − 168 switches @samp{-q} and @samp{-u} affect the use of the init file;
+ − 169 @samp{-q} says not to load an init file, and @samp{-u} says to load a
+ − 170 specified user's init file instead of yours. @xref{Entering XEmacs,,,
+ − 171 xemacs, The XEmacs User's Manual}.
+ − 172
+ − 173 @cindex default init file
+ − 174 A site may have a @dfn{default init file}, which is the library named
+ − 175 @file{default.el}. XEmacs finds the @file{default.el} file through the
+ − 176 standard search path for libraries (@pxref{How Programs Do Loading}).
+ − 177 The XEmacs distribution does not come with this file; sites may provide
+ − 178 one for local customizations. If the default init file exists, it is
+ − 179 loaded whenever you start Emacs, except in batch mode or if @samp{-q} is
+ − 180 specified. But your own personal init file, if any, is loaded first; if
+ − 181 it sets @code{inhibit-default-init} to a non-@code{nil} value, then
+ − 182 XEmacs does not subsequently load the @file{default.el} file.
+ − 183
+ − 184 Another file for site-customization is @file{site-start.el}. Emacs
+ − 185 loads this @emph{before} the user's init file. You can inhibit the
+ − 186 loading of this file with the option @samp{-no-site-file}.
+ − 187
+ − 188 @defvar site-run-file
+ − 189 This variable specifies the site-customization file to load
+ − 190 before the user's init file. Its normal value is @code{"site-start"}.
+ − 191 @end defvar
+ − 192
+ − 193 If there is a great deal of code in your @file{.emacs} file, you
+ − 194 should move it into another file named @file{@var{something}.el},
+ − 195 byte-compile it (@pxref{Byte Compilation}), and make your @file{.emacs}
+ − 196 file load the other file using @code{load} (@pxref{Loading}).
+ − 197
+ − 198 @xref{Init File Examples,,, xemacs, The XEmacs User's Manual}, for
+ − 199 examples of how to make various commonly desired customizations in your
+ − 200 @file{.emacs} file.
+ − 201
+ − 202 @defopt inhibit-default-init
+ − 203 This variable prevents XEmacs from loading the default initialization
+ − 204 library file for your session of XEmacs. If its value is non-@code{nil},
+ − 205 then the default library is not loaded. The default value is
+ − 206 @code{nil}.
+ − 207 @end defopt
+ − 208
+ − 209 @defvar before-init-hook
+ − 210 @defvarx after-init-hook
+ − 211 These two normal hooks are run just before, and just after, loading of
+ − 212 the user's init file, @file{default.el}, and/or @file{site-start.el}.
+ − 213 @end defvar
+ − 214
+ − 215 @node Terminal-Specific
+ − 216 @subsection Terminal-Specific Initialization
+ − 217 @cindex terminal-specific initialization
+ − 218
+ − 219 Each terminal type can have its own Lisp library that XEmacs loads when
+ − 220 run on that type of terminal. For a terminal type named @var{termtype},
+ − 221 the library is called @file{term/@var{termtype}}. XEmacs finds the file
+ − 222 by searching the @code{load-path} directories as it does for other
+ − 223 files, and trying the @samp{.elc} and @samp{.el} suffixes. Normally,
+ − 224 terminal-specific Lisp library is located in @file{emacs/lisp/term}, a
+ − 225 subdirectory of the @file{emacs/lisp} directory in which most XEmacs Lisp
+ − 226 libraries are kept.@refill
+ − 227
+ − 228 The library's name is constructed by concatenating the value of the
+ − 229 variable @code{term-file-prefix} and the terminal type. Normally,
+ − 230 @code{term-file-prefix} has the value @code{"term/"}; changing this
+ − 231 is not recommended.
+ − 232
+ − 233 The usual function of a terminal-specific library is to enable special
+ − 234 keys to send sequences that XEmacs can recognize. It may also need to
+ − 235 set or add to @code{function-key-map} if the Termcap entry does not
+ − 236 specify all the terminal's function keys. @xref{Terminal Input}.
+ − 237
+ − 238 @cindex Termcap
+ − 239 When the name of the terminal type contains a hyphen, only the part of
+ − 240 the name before the first hyphen is significant in choosing the library
+ − 241 name. Thus, terminal types @samp{aaa-48} and @samp{aaa-30-rv} both use
+ − 242 the @file{term/aaa} library. If necessary, the library can evaluate
+ − 243 @code{(getenv "TERM")} to find the full name of the terminal
+ − 244 type.@refill
+ − 245
+ − 246 Your @file{.emacs} file can prevent the loading of the
+ − 247 terminal-specific library by setting the variable
+ − 248 @code{term-file-prefix} to @code{nil}. This feature is useful when
+ − 249 experimenting with your own peculiar customizations.
+ − 250
+ − 251 You can also arrange to override some of the actions of the
+ − 252 terminal-specific library by setting the variable
+ − 253 @code{term-setup-hook}. This is a normal hook which XEmacs runs using
+ − 254 @code{run-hooks} at the end of XEmacs initialization, after loading both
+ − 255 your @file{.emacs} file and any terminal-specific libraries. You can
+ − 256 use this variable to define initializations for terminals that do not
+ − 257 have their own libraries. @xref{Hooks}.
+ − 258
+ − 259 @defvar term-file-prefix
+ − 260 @cindex @code{TERM} environment variable
+ − 261 If the @code{term-file-prefix} variable is non-@code{nil}, XEmacs loads
+ − 262 a terminal-specific initialization file as follows:
+ − 263
+ − 264 @example
+ − 265 (load (concat term-file-prefix (getenv "TERM")))
+ − 266 @end example
+ − 267
+ − 268 @noindent
+ − 269 You may set the @code{term-file-prefix} variable to @code{nil} in your
+ − 270 @file{.emacs} file if you do not wish to load the
+ − 271 terminal-initialization file. To do this, put the following in
+ − 272 your @file{.emacs} file: @code{(setq term-file-prefix nil)}.
+ − 273 @end defvar
+ − 274
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+ − 275 @defvar term-setup-hook
428
+ − 276 This variable is a normal hook that XEmacs runs after loading your
+ − 277 @file{.emacs} file, the default initialization file (if any) and the
+ − 278 terminal-specific Lisp file.
+ − 279
+ − 280 You can use @code{term-setup-hook} to override the definitions made by a
+ − 281 terminal-specific file.
+ − 282 @end defvar
+ − 283
+ − 284 @defvar window-setup-hook
+ − 285 This variable is a normal hook which XEmacs runs after loading your
+ − 286 @file{.emacs} file and the default initialization file (if any), after
+ − 287 loading terminal-specific Lisp code, and after running the hook
+ − 288 @code{term-setup-hook}.
+ − 289 @end defvar
+ − 290
+ − 291 @node Command Line Arguments
+ − 292 @subsection Command Line Arguments
+ − 293 @cindex command line arguments
+ − 294
+ − 295 You can use command line arguments to request various actions when you
+ − 296 start XEmacs. Since you do not need to start XEmacs more than once per
+ − 297 day, and will often leave your XEmacs session running longer than that,
+ − 298 command line arguments are hardly ever used. As a practical matter, it
+ − 299 is best to avoid making the habit of using them, since this habit would
+ − 300 encourage you to kill and restart XEmacs unnecessarily often. These
+ − 301 options exist for two reasons: to be compatible with other editors (for
+ − 302 invocation by other programs) and to enable shell scripts to run
+ − 303 specific Lisp programs.
+ − 304
+ − 305 This section describes how Emacs processes command line arguments,
+ − 306 and how you can customize them.
+ − 307
+ − 308 @ignore
+ − 309 (Note that some other editors require you to start afresh each time
+ − 310 you want to edit a file. With this kind of editor, you will probably
+ − 311 specify the file as a command line argument. The recommended way to
+ − 312 use XEmacs is to start it only once, just after you log in, and do
+ − 313 all your editing in the same XEmacs process. Each time you want to edit
+ − 314 a different file, you visit it with the existing XEmacs, which eventually
+ − 315 comes to have many files in it ready for editing. Usually you do not
+ − 316 kill the XEmacs until you are about to log out.)
+ − 317 @end ignore
+ − 318
+ − 319 @defun command-line
+ − 320 This function parses the command line that XEmacs was called with,
+ − 321 processes it, loads the user's @file{.emacs} file and displays the
+ − 322 startup messages.
+ − 323 @end defun
+ − 324
+ − 325 @defvar command-line-processed
+ − 326 The value of this variable is @code{t} once the command line has been
+ − 327 processed.
+ − 328
+ − 329 If you redump XEmacs by calling @code{dump-emacs}, you may wish to set
+ − 330 this variable to @code{nil} first in order to cause the new dumped XEmacs
+ − 331 to process its new command line arguments.
+ − 332 @end defvar
+ − 333
+ − 334 @defvar command-switch-alist
+ − 335 @cindex switches on command line
+ − 336 @cindex options on command line
+ − 337 @cindex command line options
+ − 338 The value of this variable is an alist of user-defined command-line
+ − 339 options and associated handler functions. This variable exists so you
+ − 340 can add elements to it.
+ − 341
+ − 342 A @dfn{command line option} is an argument on the command line of the
+ − 343 form:
+ − 344
+ − 345 @example
+ − 346 -@var{option}
+ − 347 @end example
+ − 348
444
+ − 349 The elements of the @code{command-switch-alist} look like this:
428
+ − 350
+ − 351 @example
+ − 352 (@var{option} . @var{handler-function})
+ − 353 @end example
+ − 354
+ − 355 The @var{handler-function} is called to handle @var{option} and receives
+ − 356 the option name as its sole argument.
+ − 357
+ − 358 In some cases, the option is followed in the command line by an
+ − 359 argument. In these cases, the @var{handler-function} can find all the
+ − 360 remaining command-line arguments in the variable
+ − 361 @code{command-line-args-left}. (The entire list of command-line
+ − 362 arguments is in @code{command-line-args}.)
+ − 363
+ − 364 The command line arguments are parsed by the @code{command-line-1}
+ − 365 function in the @file{startup.el} file. See also @ref{Command
+ − 366 Switches, , Command Line Switches and Arguments, xemacs, The XEmacs
+ − 367 User's Manual}.
+ − 368 @end defvar
+ − 369
+ − 370 @defvar command-line-args
+ − 371 The value of this variable is the list of command line arguments passed
+ − 372 to XEmacs.
+ − 373 @end defvar
+ − 374
+ − 375 @defvar command-line-functions
+ − 376 This variable's value is a list of functions for handling an
+ − 377 unrecognized command-line argument. Each time the next argument to be
+ − 378 processed has no special meaning, the functions in this list are called,
+ − 379 in order of appearance, until one of them returns a non-@code{nil}
+ − 380 value.
+ − 381
+ − 382 These functions are called with no arguments. They can access the
+ − 383 command-line argument under consideration through the variable
+ − 384 @code{argi}. The remaining arguments (not including the current one)
+ − 385 are in the variable @code{command-line-args-left}.
+ − 386
+ − 387 When a function recognizes and processes the argument in @code{argi}, it
+ − 388 should return a non-@code{nil} value to say it has dealt with that
+ − 389 argument. If it has also dealt with some of the following arguments, it
+ − 390 can indicate that by deleting them from @code{command-line-args-left}.
+ − 391
+ − 392 If all of these functions return @code{nil}, then the argument is used
+ − 393 as a file name to visit.
+ − 394 @end defvar
+ − 395
+ − 396 @node Getting Out
+ − 397 @section Getting out of XEmacs
+ − 398 @cindex exiting XEmacs
+ − 399
+ − 400 There are two ways to get out of XEmacs: you can kill the XEmacs job,
+ − 401 which exits permanently, or you can suspend it, which permits you to
+ − 402 reenter the XEmacs process later. As a practical matter, you seldom kill
+ − 403 XEmacs---only when you are about to log out. Suspending is much more
+ − 404 common.
+ − 405
+ − 406 @menu
+ − 407 * Killing XEmacs:: Exiting XEmacs irreversibly.
+ − 408 * Suspending XEmacs:: Exiting XEmacs reversibly.
+ − 409 @end menu
+ − 410
+ − 411 @node Killing XEmacs
+ − 412 @subsection Killing XEmacs
+ − 413 @cindex killing XEmacs
+ − 414
+ − 415 Killing XEmacs means ending the execution of the XEmacs process. The
+ − 416 parent process normally resumes control. The low-level primitive for
+ − 417 killing XEmacs is @code{kill-emacs}.
+ − 418
444
+ − 419 @deffn Command kill-emacs &optional exit-data
428
+ − 420 This function exits the XEmacs process and kills it.
+ − 421
+ − 422 If @var{exit-data} is an integer, then it is used as the exit status
+ − 423 of the XEmacs process. (This is useful primarily in batch operation; see
+ − 424 @ref{Batch Mode}.)
+ − 425
+ − 426 If @var{exit-data} is a string, its contents are stuffed into the
+ − 427 terminal input buffer so that the shell (or whatever program next reads
+ − 428 input) can read them.
444
+ − 429 @end deffn
428
+ − 430
+ − 431 All the information in the XEmacs process, aside from files that have
+ − 432 been saved, is lost when the XEmacs is killed. Because killing XEmacs
+ − 433 inadvertently can lose a lot of work, XEmacs queries for confirmation
+ − 434 before actually terminating if you have buffers that need saving or
+ − 435 subprocesses that are running. This is done in the function
+ − 436 @code{save-buffers-kill-emacs}.
+ − 437
+ − 438 @defvar kill-emacs-query-functions
+ − 439 After asking the standard questions, @code{save-buffers-kill-emacs}
+ − 440 calls the functions in the list @code{kill-buffer-query-functions}, in
+ − 441 order of appearance, with no arguments. These functions can ask for
+ − 442 additional confirmation from the user. If any of them returns
+ − 443 non-@code{nil}, XEmacs is not killed.
+ − 444 @end defvar
+ − 445
+ − 446 @defvar kill-emacs-hook
+ − 447 This variable is a normal hook; once @code{save-buffers-kill-emacs} is
+ − 448 finished with all file saving and confirmation, it runs the functions in
+ − 449 this hook.
+ − 450 @end defvar
+ − 451
+ − 452 @node Suspending XEmacs
+ − 453 @subsection Suspending XEmacs
+ − 454 @cindex suspending XEmacs
+ − 455
+ − 456 @dfn{Suspending XEmacs} means stopping XEmacs temporarily and returning
+ − 457 control to its superior process, which is usually the shell. This
+ − 458 allows you to resume editing later in the same XEmacs process, with the
+ − 459 same buffers, the same kill ring, the same undo history, and so on. To
+ − 460 resume XEmacs, use the appropriate command in the parent shell---most
+ − 461 likely @code{fg}.
+ − 462
+ − 463 Some operating systems do not support suspension of jobs; on these
+ − 464 systems, ``suspension'' actually creates a new shell temporarily as a
+ − 465 subprocess of XEmacs. Then you would exit the shell to return to XEmacs.
+ − 466
+ − 467 Suspension is not useful with window systems such as X, because the
+ − 468 XEmacs job may not have a parent that can resume it again, and in any
+ − 469 case you can give input to some other job such as a shell merely by
+ − 470 moving to a different window. Therefore, suspending is not allowed
+ − 471 when XEmacs is an X client.
+ − 472
444
+ − 473 @deffn Command suspend-emacs &optional stuffstring
428
+ − 474 This function stops XEmacs and returns control to the superior process.
+ − 475 If and when the superior process resumes XEmacs, @code{suspend-emacs}
+ − 476 returns @code{nil} to its caller in Lisp.
+ − 477
444
+ − 478 If optional arg @var{stuffstring} is non-@code{nil}, its characters are
+ − 479 sent to be read as terminal input by XEmacs's superior shell. The
+ − 480 characters in @var{stuffstring} are not echoed by the superior shell;
+ − 481 only the results appear.
428
+ − 482
+ − 483 Before suspending, @code{suspend-emacs} runs the normal hook
+ − 484 @code{suspend-hook}. In Emacs version 18, @code{suspend-hook} was not a
+ − 485 normal hook; its value was a single function, and if its value was
+ − 486 non-@code{nil}, then @code{suspend-emacs} returned immediately without
+ − 487 actually suspending anything.
+ − 488
+ − 489 After the user resumes XEmacs, @code{suspend-emacs} runs the normal hook
+ − 490 @code{suspend-resume-hook}. @xref{Hooks}.
+ − 491
+ − 492 The next redisplay after resumption will redraw the entire screen,
+ − 493 unless the variable @code{no-redraw-on-reenter} is non-@code{nil}
+ − 494 (@pxref{Refresh Screen}).
+ − 495
+ − 496 In the following example, note that @samp{pwd} is not echoed after
+ − 497 XEmacs is suspended. But it is read and executed by the shell.
+ − 498
+ − 499 @smallexample
+ − 500 @group
+ − 501 (suspend-emacs)
+ − 502 @result{} nil
+ − 503 @end group
+ − 504
+ − 505 @group
+ − 506 (add-hook 'suspend-hook
+ − 507 (function (lambda ()
+ − 508 (or (y-or-n-p
+ − 509 "Really suspend? ")
+ − 510 (error "Suspend cancelled")))))
+ − 511 @result{} (lambda nil
+ − 512 (or (y-or-n-p "Really suspend? ")
+ − 513 (error "Suspend cancelled")))
+ − 514 @end group
+ − 515 @group
+ − 516 (add-hook 'suspend-resume-hook
+ − 517 (function (lambda () (message "Resumed!"))))
+ − 518 @result{} (lambda nil (message "Resumed!"))
+ − 519 @end group
+ − 520 @group
+ − 521 (suspend-emacs "pwd")
+ − 522 @result{} nil
+ − 523 @end group
+ − 524 @group
+ − 525 ---------- Buffer: Minibuffer ----------
+ − 526 Really suspend? @kbd{y}
+ − 527 ---------- Buffer: Minibuffer ----------
+ − 528 @end group
+ − 529
+ − 530 @group
+ − 531 ---------- Parent Shell ----------
+ − 532 lewis@@slug[23] % /user/lewis/manual
+ − 533 lewis@@slug[24] % fg
+ − 534 @end group
+ − 535
+ − 536 @group
+ − 537 ---------- Echo Area ----------
+ − 538 Resumed!
+ − 539 @end group
+ − 540 @end smallexample
444
+ − 541 @end deffn
428
+ − 542
+ − 543 @defvar suspend-hook
+ − 544 This variable is a normal hook run before suspending.
+ − 545 @end defvar
+ − 546
+ − 547 @defvar suspend-resume-hook
+ − 548 This variable is a normal hook run after suspending.
+ − 549 @end defvar
+ − 550
+ − 551 @node System Environment
+ − 552 @section Operating System Environment
+ − 553 @cindex operating system environment
+ − 554
+ − 555 XEmacs provides access to variables in the operating system environment
+ − 556 through various functions. These variables include the name of the
+ − 557 system, the user's @sc{uid}, and so on.
+ − 558
+ − 559 @defvar system-type
+ − 560 The value of this variable is a symbol indicating the type of operating
+ − 561 system XEmacs is operating on. Here is a table of the possible values:
+ − 562
+ − 563 @table @code
+ − 564 @item aix-v3
+ − 565 AIX.
+ − 566
+ − 567 @item berkeley-unix
+ − 568 Berkeley BSD.
+ − 569
+ − 570 @item dgux
+ − 571 Data General DGUX operating system.
+ − 572
+ − 573 @item gnu
+ − 574 A GNU system using the GNU HURD and Mach.
+ − 575
+ − 576 @item hpux
+ − 577 Hewlett-Packard HPUX operating system.
+ − 578
+ − 579 @item irix
+ − 580 Silicon Graphics Irix system.
+ − 581
+ − 582 @item linux
+ − 583 A GNU system using the Linux kernel.
+ − 584
+ − 585 @item ms-dos
+ − 586 Microsoft MS-DOS ``operating system.''
+ − 587
+ − 588 @item next-mach
+ − 589 NeXT Mach-based system.
+ − 590
+ − 591 @item rtu
+ − 592 Masscomp RTU, UCB universe.
+ − 593
+ − 594 @item unisoft-unix
+ − 595 UniSoft UniPlus.
+ − 596
+ − 597 @item usg-unix-v
+ − 598 AT&T System V.
+ − 599
+ − 600 @item windows-nt
+ − 601 Microsoft windows NT.
+ − 602
+ − 603 @item xenix
+ − 604 SCO Xenix 386.
+ − 605 @end table
+ − 606
+ − 607 We do not wish to add new symbols to make finer distinctions unless it
+ − 608 is absolutely necessary! In fact, we hope to eliminate some of these
+ − 609 alternatives in the future. We recommend using
+ − 610 @code{system-configuration} to distinguish between different operating
+ − 611 systems.
+ − 612 @end defvar
+ − 613
+ − 614 @defvar system-configuration
+ − 615 This variable holds the three-part configuration name for the
+ − 616 hardware/software configuration of your system, as a string. The
+ − 617 convenient way to test parts of this string is with @code{string-match}.
+ − 618 @end defvar
+ − 619
+ − 620 @defun system-name
+ − 621 This function returns the name of the machine you are running on.
+ − 622 @example
+ − 623 (system-name)
+ − 624 @result{} "prep.ai.mit.edu"
+ − 625 @end example
+ − 626 @end defun
+ − 627
+ − 628 @vindex system-name
+ − 629 The symbol @code{system-name} is a variable as well as a function. In
+ − 630 fact, the function returns whatever value the variable
+ − 631 @code{system-name} currently holds. Thus, you can set the variable
+ − 632 @code{system-name} in case Emacs is confused about the name of your
+ − 633 system. The variable is also useful for constructing frame titles
+ − 634 (@pxref{Frame Titles}).
+ − 635
+ − 636 @defvar mail-host-address
+ − 637 If this variable is non-@code{nil}, it is used instead of
+ − 638 @code{system-name} for purposes of generating email addresses. For
+ − 639 example, it is used when constructing the default value of
+ − 640 @code{user-mail-address}. @xref{User Identification}. (Since this is
+ − 641 done when XEmacs starts up, the value actually used is the one saved when
+ − 642 XEmacs was dumped. @xref{Building XEmacs}.)
+ − 643 @end defvar
+ − 644
444
+ − 645 @deffn Command getenv var &optional interactivep
428
+ − 646 @cindex environment variable access
+ − 647 This function returns the value of the environment variable @var{var},
+ − 648 as a string. Within XEmacs, the environment variable values are kept in
+ − 649 the Lisp variable @code{process-environment}.
+ − 650
444
+ − 651 When invoked interactively, @code{getenv} prints the value in the echo area.
+ − 652
428
+ − 653 @example
+ − 654 @group
+ − 655 (getenv "USER")
+ − 656 @result{} "lewis"
+ − 657 @end group
+ − 658
+ − 659 @group
+ − 660 lewis@@slug[10] % printenv
+ − 661 PATH=.:/user/lewis/bin:/usr/bin:/usr/local/bin
+ − 662 USER=lewis
+ − 663 @end group
+ − 664 @group
+ − 665 TERM=ibmapa16
+ − 666 SHELL=/bin/csh
+ − 667 HOME=/user/lewis
+ − 668 @end group
+ − 669 @end example
444
+ − 670 @end deffn
428
+ − 671
444
+ − 672 @deffn Command setenv variable &optional value unset
428
+ − 673 This command sets the value of the environment variable named
+ − 674 @var{variable} to @var{value}. Both arguments should be strings. This
+ − 675 function works by modifying @code{process-environment}; binding that
+ − 676 variable with @code{let} is also reasonable practice.
+ − 677 @end deffn
+ − 678
+ − 679 @defvar process-environment
+ − 680 This variable is a list of strings, each describing one environment
444
+ − 681 variable. The functions @code{getenv} and @code{setenv} work by
+ − 682 manipulating this variable.
428
+ − 683
+ − 684 @smallexample
+ − 685 @group
+ − 686 process-environment
+ − 687 @result{} ("l=/usr/stanford/lib/gnuemacs/lisp"
+ − 688 "PATH=.:/user/lewis/bin:/usr/class:/nfsusr/local/bin"
444
+ − 689 "USER=lewis"
428
+ − 690 @end group
+ − 691 @group
444
+ − 692 "TERM=ibmapa16"
428
+ − 693 "SHELL=/bin/csh"
+ − 694 "HOME=/user/lewis")
+ − 695 @end group
+ − 696 @end smallexample
+ − 697 @end defvar
+ − 698
+ − 699 @defvar path-separator
+ − 700 This variable holds a string which says which character separates
+ − 701 directories in a search path (as found in an environment variable). Its
+ − 702 value is @code{":"} for Unix and GNU systems, and @code{";"} for MS-DOS
+ − 703 and Windows NT.
+ − 704 @end defvar
+ − 705
+ − 706 @defvar invocation-name
+ − 707 This variable holds the program name under which Emacs was invoked. The
+ − 708 value is a string, and does not include a directory name.
+ − 709 @end defvar
+ − 710
+ − 711 @defvar invocation-directory
+ − 712 This variable holds the directory from which the Emacs executable was
+ − 713 invoked, or perhaps @code{nil} if that directory cannot be determined.
+ − 714 @end defvar
+ − 715
+ − 716 @defvar installation-directory
+ − 717 If non-@code{nil}, this is a directory within which to look for the
+ − 718 @file{lib-src} and @file{etc} subdirectories. This is non-@code{nil}
+ − 719 when Emacs can't find those directories in their standard installed
+ − 720 locations, but can find them in a directory related somehow to the one
+ − 721 containing the Emacs executable.
+ − 722 @end defvar
+ − 723
+ − 724 @defun load-average &optional use-floats
+ − 725 This function returns a list of the current 1-minute, 5-minute and
+ − 726 15-minute load averages. The values are integers that are 100 times the
+ − 727 system load averages. (The load averages indicate the number of
+ − 728 processes trying to run.)
+ − 729
444
+ − 730 When @var{use-floats} is non-@code{nil}, floats will be returned instead
428
+ − 731 of integers. These floats are not multiplied by 100.
+ − 732
+ − 733 @example
+ − 734 @group
+ − 735 (load-average)
+ − 736 @result{} (169 158 164)
+ − 737 (load-average t)
+ − 738 @result{} (1.69921875 1.58984375 1.640625)
+ − 739 @end group
+ − 740
+ − 741 @group
+ − 742 lewis@@rocky[5] % uptime
+ − 743 8:06pm up 16 day(s), 21:57, 40 users,
+ − 744 load average: 1.68, 1.59, 1.64
+ − 745 @end group
+ − 746 @end example
+ − 747
+ − 748 If the 5-minute or 15-minute load averages are not available, return a
+ − 749 shortened list, containing only those averages which are available.
+ − 750
444
+ − 751 On some systems, this function may require special privileges to run, or
428
+ − 752 it may be unimplemented for the particular system type. In that case,
+ − 753 the function will signal an error.
+ − 754 @end defun
+ − 755
+ − 756 @defun emacs-pid
+ − 757 This function returns the process @sc{id} of the Emacs process.
+ − 758 @end defun
+ − 759
+ − 760 @node User Identification
+ − 761 @section User Identification
+ − 762
+ − 763 @defvar user-mail-address
+ − 764 This holds the nominal email address of the user who is using Emacs.
+ − 765 When Emacs starts up, it computes a default value that is usually right,
+ − 766 but users often set this themselves when the default value is not right.
+ − 767 @end defvar
+ − 768
+ − 769 @defun user-login-name &optional uid
+ − 770 If you don't specify @var{uid}, this function returns the name under
+ − 771 which the user is logged in. If the environment variable @code{LOGNAME}
+ − 772 is set, that value is used. Otherwise, if the environment variable
+ − 773 @code{USER} is set, that value is used. Otherwise, the value is based
+ − 774 on the effective @sc{uid}, not the real @sc{uid}.
+ − 775
+ − 776 If you specify @var{uid}, the value is the user name that corresponds
+ − 777 to @var{uid} (which should be an integer).
+ − 778
+ − 779 @example
+ − 780 @group
+ − 781 (user-login-name)
+ − 782 @result{} "lewis"
+ − 783 @end group
+ − 784 @end example
+ − 785 @end defun
+ − 786
+ − 787 @defun user-real-login-name
+ − 788 This function returns the user name corresponding to Emacs's real
+ − 789 @sc{uid}. This ignores the effective @sc{uid} and ignores the
+ − 790 environment variables @code{LOGNAME} and @code{USER}.
+ − 791 @end defun
+ − 792
+ − 793 @defvar user-full-name
+ − 794 This variable holds the name of the user running this Emacs. It is
+ − 795 initialized at startup time from the value of @code{NAME} environment
444
+ − 796 variable. You can change the value of this variable to alter the result
428
+ − 797 of the @code{user-full-name} function.
+ − 798 @end defvar
+ − 799
+ − 800 @defun user-full-name &optional user
+ − 801 This function returns the full name of @var{user}. If @var{user} is
+ − 802 @code{nil}, it defaults to the user running this Emacs. In that case,
+ − 803 the value of @code{user-full-name} variable, if non-@code{nil}, will be
+ − 804 used.
+ − 805
444
+ − 806 If @var{user} is specified explicitly, @code{user-full-name} variable is
428
+ − 807 ignored.
+ − 808
+ − 809 @example
+ − 810 @group
+ − 811 (user-full-name)
+ − 812 @result{} "Hrvoje Niksic"
+ − 813 (setq user-full-name "Hrvoje \"Niksa\" Niksic")
+ − 814 (user-full-name)
+ − 815 @result{} "Hrvoje \"Niksa\" Niksic"
+ − 816 (user-full-name "hniksic")
+ − 817 @result{} "Hrvoje Niksic"
+ − 818 @end group
+ − 819 @end example
+ − 820 @end defun
+ − 821
+ − 822 @vindex user-full-name
+ − 823 @vindex user-real-login-name
+ − 824 @vindex user-login-name
+ − 825 The symbols @code{user-login-name}, @code{user-real-login-name} and
+ − 826 @code{user-full-name} are variables as well as functions. The functions
+ − 827 return the same values that the variables hold. These variables allow
+ − 828 you to ``fake out'' Emacs by telling the functions what to return. The
+ − 829 variables are also useful for constructing frame titles (@pxref{Frame
+ − 830 Titles}).
+ − 831
+ − 832 @defun user-real-uid
+ − 833 This function returns the real @sc{uid} of the user.
+ − 834
+ − 835 @example
+ − 836 @group
+ − 837 (user-real-uid)
+ − 838 @result{} 19
+ − 839 @end group
+ − 840 @end example
+ − 841 @end defun
+ − 842
+ − 843 @defun user-uid
444
+ − 844 This function returns the effective @sc{uid} of the user.
428
+ − 845 @end defun
+ − 846
+ − 847 @defun user-home-directory
+ − 848 This function returns the ``@code{HOME}'' directory of the user, and is
+ − 849 intended to replace occurrences of ``@code{(getenv "HOME")}''. Under
+ − 850 Unix systems, the following is done:
+ − 851
+ − 852 @enumerate
+ − 853 @item
+ − 854 Return the value of ``@code{(getenv "HOME")}'', if set.
+ − 855
+ − 856 @item
+ − 857 Return ``/'', as a fallback, but issue a warning. (Future versions of
+ − 858 XEmacs will also attempt to lookup the @code{HOME} directory via
+ − 859 @code{getpwent()}, but this has not yet been implemented.)
+ − 860 @end enumerate
+ − 861
+ − 862 Under MS Windows, this is done:
+ − 863
+ − 864 @enumerate
+ − 865 @item
+ − 866 Return the value of ``@code{(getenv "HOME")}'', if set.
+ − 867
+ − 868 @item
3772
+ − 869 If the environment variables @code{HOMEDRIVE} and @code{HOMEPATH} are
428
+ − 870 both set, return the concatenation (the following description uses MS
+ − 871 Windows environment variable substitution syntax):
3772
+ − 872 @code{%HOMEDRIVE%%HOMEPATH%}.
428
+ − 873
+ − 874 @item
+ − 875 Return ``C:\'', as a fallback, but issue a warning.
+ − 876 @end enumerate
+ − 877 @end defun
+ − 878
+ − 879 @node Time of Day
+ − 880 @section Time of Day
+ − 881
+ − 882 This section explains how to determine the current time and the time
+ − 883 zone.
+ − 884
+ − 885 @defun current-time-string &optional time-value
+ − 886 This function returns the current time and date as a humanly-readable
+ − 887 string. The format of the string is unvarying; the number of characters
+ − 888 used for each part is always the same, so you can reliably use
+ − 889 @code{substring} to extract pieces of it. It is wise to count the
+ − 890 characters from the beginning of the string rather than from the end, as
+ − 891 additional information may be added at the end.
+ − 892
+ − 893 @c Emacs 19 feature
+ − 894 The argument @var{time-value}, if given, specifies a time to format
+ − 895 instead of the current time. The argument should be a list whose first
+ − 896 two elements are integers. Thus, you can use times obtained from
+ − 897 @code{current-time} (see below) and from @code{file-attributes}
+ − 898 (@pxref{File Attributes}).
+ − 899
+ − 900 @example
+ − 901 @group
+ − 902 (current-time-string)
+ − 903 @result{} "Wed Oct 14 22:21:05 1987"
+ − 904 @end group
+ − 905 @end example
+ − 906 @end defun
+ − 907
+ − 908 @c Emacs 19 feature
+ − 909 @defun current-time
+ − 910 This function returns the system's time value as a list of three
+ − 911 integers: @code{(@var{high} @var{low} @var{microsec})}. The integers
+ − 912 @var{high} and @var{low} combine to give the number of seconds since
+ − 913 0:00 January 1, 1970, which is
+ − 914 @ifinfo
+ − 915 @var{high} * 2**16 + @var{low}.
+ − 916 @end ifinfo
+ − 917 @tex
+ − 918 $high*2^{16}+low$.
+ − 919 @end tex
+ − 920
+ − 921 The third element, @var{microsec}, gives the microseconds since the
+ − 922 start of the current second (or 0 for systems that return time only on
+ − 923 the resolution of a second).
+ − 924
+ − 925 The first two elements can be compared with file time values such as you
+ − 926 get with the function @code{file-attributes}. @xref{File Attributes}.
+ − 927 @end defun
+ − 928
+ − 929 @c Emacs 19 feature
+ − 930 @defun current-time-zone &optional time-value
+ − 931 This function returns a list describing the time zone that the user is
+ − 932 in.
+ − 933
+ − 934 The value has the form @code{(@var{offset} @var{name})}. Here
+ − 935 @var{offset} is an integer giving the number of seconds ahead of UTC
+ − 936 (east of Greenwich). A negative value means west of Greenwich. The
+ − 937 second element, @var{name} is a string giving the name of the time
+ − 938 zone. Both elements change when daylight savings time begins or ends;
+ − 939 if the user has specified a time zone that does not use a seasonal time
+ − 940 adjustment, then the value is constant through time.
+ − 941
+ − 942 If the operating system doesn't supply all the information necessary to
+ − 943 compute the value, both elements of the list are @code{nil}.
+ − 944
+ − 945 The argument @var{time-value}, if given, specifies a time to analyze
+ − 946 instead of the current time. The argument should be a cons cell
+ − 947 containing two integers, or a list whose first two elements are
+ − 948 integers. Thus, you can use times obtained from @code{current-time}
+ − 949 (see above) and from @code{file-attributes} (@pxref{File Attributes}).
+ − 950 @end defun
+ − 951
+ − 952 @node Time Conversion
+ − 953 @section Time Conversion
+ − 954
+ − 955 These functions convert time values (lists of two or three integers)
+ − 956 to strings or to calendrical information. There is also a function to
+ − 957 convert calendrical information to a time value. You can get time
+ − 958 values from the functions @code{current-time} (@pxref{Time of Day}) and
+ − 959 @code{file-attributes} (@pxref{File Attributes}).
+ − 960
+ − 961 @defun format-time-string format-string &optional time
+ − 962 This function converts @var{time} to a string according to
+ − 963 @var{format-string}. If @var{time} is omitted, it defaults to the
+ − 964 current time. The argument @var{format-string} may contain
+ − 965 @samp{%}-sequences which say to substitute parts of the time. Here is a
+ − 966 table of what the @samp{%}-sequences mean:
+ − 967
+ − 968 @table @samp
+ − 969 @item %a
+ − 970 This stands for the abbreviated name of the day of week.
+ − 971 @item %A
+ − 972 This stands for the full name of the day of week.
+ − 973 @item %b
+ − 974 This stands for the abbreviated name of the month.
+ − 975 @item %B
+ − 976 This stands for the full name of the month.
+ − 977 @item %c
+ − 978 This is a synonym for @samp{%x %X}.
+ − 979 @item %C
+ − 980 This has a locale-specific meaning. In the default locale (named C), it
+ − 981 is equivalent to @samp{%A, %B %e, %Y}.
+ − 982 @item %d
+ − 983 This stands for the day of month, zero-padded.
+ − 984 @item %D
+ − 985 This is a synonym for @samp{%m/%d/%y}.
+ − 986 @item %e
+ − 987 This stands for the day of month, blank-padded.
+ − 988 @item %h
+ − 989 This is a synonym for @samp{%b}.
+ − 990 @item %H
+ − 991 This stands for the hour (00-23).
+ − 992 @item %I
+ − 993 This stands for the hour (00-12).
+ − 994 @item %j
+ − 995 This stands for the day of the year (001-366).
+ − 996 @item %k
+ − 997 This stands for the hour (0-23), blank padded.
+ − 998 @item %l
+ − 999 This stands for the hour (1-12), blank padded.
+ − 1000 @item %m
+ − 1001 This stands for the month (01-12).
+ − 1002 @item %M
+ − 1003 This stands for the minute (00-59).
+ − 1004 @item %n
+ − 1005 This stands for a newline.
+ − 1006 @item %p
+ − 1007 This stands for @samp{AM} or @samp{PM}, as appropriate.
+ − 1008 @item %r
+ − 1009 This is a synonym for @samp{%I:%M:%S %p}.
+ − 1010 @item %R
+ − 1011 This is a synonym for @samp{%H:%M}.
+ − 1012 @item %S
+ − 1013 This stands for the seconds (00-60).
+ − 1014 @item %t
+ − 1015 This stands for a tab character.
+ − 1016 @item %T
+ − 1017 This is a synonym for @samp{%H:%M:%S}.
+ − 1018 @item %U
+ − 1019 This stands for the week of the year (01-52), assuming that weeks
+ − 1020 start on Sunday.
+ − 1021 @item %w
+ − 1022 This stands for the numeric day of week (0-6). Sunday is day 0.
+ − 1023 @item %W
+ − 1024 This stands for the week of the year (01-52), assuming that weeks
+ − 1025 start on Monday.
+ − 1026 @item %x
+ − 1027 This has a locale-specific meaning. In the default locale (named C), it
+ − 1028 is equivalent to @samp{%D}.
+ − 1029 @item %X
+ − 1030 This has a locale-specific meaning. In the default locale (named C), it
+ − 1031 is equivalent to @samp{%T}.
+ − 1032 @item %y
+ − 1033 This stands for the year without century (00-99).
+ − 1034 @item %Y
+ − 1035 This stands for the year with century.
+ − 1036 @item %Z
+ − 1037 This stands for the time zone abbreviation.
+ − 1038 @end table
+ − 1039 @end defun
+ − 1040
444
+ − 1041 @defun decode-time &optional specified-time
428
+ − 1042 This function converts a time value into calendrical information. The
444
+ − 1043 optional @var{specified-time} should be a list of
+ − 1044 (@var{high} @var{low} . @var{ignored}) or (@var{high} . @var{low}), as from
+ − 1045 @code{current-time} and @code{file-attributes}, or @code{nil} to use the
+ − 1046 current time.
+ − 1047
+ − 1048 The return value is a list of nine elements, as follows:
428
+ − 1049
+ − 1050 @example
+ − 1051 (@var{seconds} @var{minutes} @var{hour} @var{day} @var{month} @var{year} @var{dow} @var{dst} @var{zone})
+ − 1052 @end example
+ − 1053
+ − 1054 Here is what the elements mean:
+ − 1055
+ − 1056 @table @var
+ − 1057 @item sec
+ − 1058 The number of seconds past the minute, as an integer between 0 and 59.
+ − 1059 @item minute
+ − 1060 The number of minutes past the hour, as an integer between 0 and 59.
+ − 1061 @item hour
+ − 1062 The hour of the day, as an integer between 0 and 23.
+ − 1063 @item day
+ − 1064 The day of the month, as an integer between 1 and 31.
+ − 1065 @item month
+ − 1066 The month of the year, as an integer between 1 and 12.
+ − 1067 @item year
+ − 1068 The year, an integer typically greater than 1900.
+ − 1069 @item dow
+ − 1070 The day of week, as an integer between 0 and 6, where 0 stands for
+ − 1071 Sunday.
+ − 1072 @item dst
+ − 1073 @code{t} if daylight savings time is effect, otherwise @code{nil}.
+ − 1074 @item zone
+ − 1075 An integer indicating the time zone, as the number of seconds east of
+ − 1076 Greenwich.
+ − 1077 @end table
+ − 1078
+ − 1079 Note that Common Lisp has different meanings for @var{dow} and
+ − 1080 @var{zone}.
+ − 1081 @end defun
+ − 1082
+ − 1083 @defun encode-time seconds minutes hour day month year &optional zone
+ − 1084 This function is the inverse of @code{decode-time}. It converts seven
+ − 1085 items of calendrical data into a time value. For the meanings of the
+ − 1086 arguments, see the table above under @code{decode-time}.
+ − 1087
+ − 1088 Year numbers less than 100 are treated just like other year numbers. If
+ − 1089 you want them to stand for years above 1900, you must alter them yourself
+ − 1090 before you call @code{encode-time}.
+ − 1091
+ − 1092 The optional argument @var{zone} defaults to the current time zone and
+ − 1093 its daylight savings time rules. If specified, it can be either a list
+ − 1094 (as you would get from @code{current-time-zone}) or an integer (as you
+ − 1095 would get from @code{decode-time}). The specified zone is used without
+ − 1096 any further alteration for daylight savings time.
+ − 1097 @end defun
+ − 1098
+ − 1099 @node Timers
+ − 1100 @section Timers for Delayed Execution
+ − 1101
+ − 1102 You can set up a timer to call a function at a specified future time.
+ − 1103
+ − 1104 @c All different in FSF 19
+ − 1105 @defun add-timeout secs function object &optional resignal
+ − 1106 This function adds a timeout, to be signaled after the timeout period
+ − 1107 has elapsed. @var{secs} is a number of seconds, expressed as an integer
+ − 1108 or a float. @var{function} will be called after that many seconds have
+ − 1109 elapsed, with one argument, the given @var{object}. If the optional
+ − 1110 @var{resignal} argument is provided, then after this timeout expires,
444
+ − 1111 @code{add-timeout} will automatically be called again with
+ − 1112 @var{resignal} as the first argument.
428
+ − 1113
+ − 1114 This function returns an object which is the @dfn{id} of this particular
+ − 1115 timeout. You can pass that object to @code{disable-timeout} to turn off
+ − 1116 the timeout before it has been signalled.
+ − 1117
+ − 1118 The number of seconds may be expressed as a floating-point number, in which
+ − 1119 case some fractional part of a second will be used. Caveat: the usable
+ − 1120 timeout granularity will vary from system to system.
+ − 1121
+ − 1122 Adding a timeout causes a timeout event to be returned by
+ − 1123 @code{next-event}, and the function will be invoked by
+ − 1124 @code{dispatch-event}, so if XEmacs is in a tight loop, the function will
+ − 1125 not be invoked until the next call to sit-for or until the return to
+ − 1126 top-level (the same is true of process filters).
+ − 1127
+ − 1128 WARNING: if you are thinking of calling add-timeout from inside of a
+ − 1129 callback function as a way of resignalling a timeout, think again. There
+ − 1130 is a race condition. That's why the @var{resignal} argument exists.
+ − 1131
+ − 1132 (NOTE: In FSF Emacs, this function is called @code{run-at-time} and
+ − 1133 has different semantics.)
+ − 1134 @end defun
+ − 1135
+ − 1136 @defun disable-timeout id
+ − 1137 Cancel the requested action for @var{id}, which should be a value
+ − 1138 previously returned by @code{add-timeout}. This cancels the effect of
+ − 1139 that call to @code{add-timeout}; the arrival of the specified time will
+ − 1140 not cause anything special to happen.
+ − 1141 (NOTE: In FSF Emacs, this function is called @code{cancel-timer}.)
+ − 1142 @end defun
+ − 1143
+ − 1144 @node Terminal Input
+ − 1145 @section Terminal Input
+ − 1146 @cindex terminal input
+ − 1147
+ − 1148 This section describes functions and variables for recording or
+ − 1149 manipulating terminal input. See @ref{Display}, for related
+ − 1150 functions.
+ − 1151
+ − 1152 @menu
+ − 1153 * Input Modes:: Options for how input is processed.
+ − 1154 * Translating Input:: Low level conversion of some characters or events
+ − 1155 into others.
+ − 1156 * Recording Input:: Saving histories of recent or all input events.
+ − 1157 @end menu
+ − 1158
+ − 1159 @node Input Modes
+ − 1160 @subsection Input Modes
+ − 1161 @cindex input modes
+ − 1162 @cindex terminal input modes
+ − 1163
444
+ − 1164 @defun set-input-mode interrupt flow meta &optional quit-char console
428
+ − 1165 This function sets the mode for reading keyboard input. If
+ − 1166 @var{interrupt} is non-null, then XEmacs uses input interrupts. If it is
+ − 1167 @code{nil}, then it uses @sc{cbreak} mode. When XEmacs communicates
+ − 1168 directly with X, it ignores this argument and uses interrupts if that is
+ − 1169 the way it knows how to communicate.
+ − 1170
+ − 1171 If @var{flow} is non-@code{nil}, then XEmacs uses @sc{xon/xoff} (@kbd{C-q},
+ − 1172 @kbd{C-s}) flow control for output to the terminal. This has no effect except
+ − 1173 in @sc{cbreak} mode. @xref{Flow Control}.
+ − 1174
+ − 1175 The default setting is system dependent. Some systems always use
+ − 1176 @sc{cbreak} mode regardless of what is specified.
+ − 1177
+ − 1178 @c Emacs 19 feature
+ − 1179 The argument @var{meta} controls support for input character codes
+ − 1180 above 127. If @var{meta} is @code{t}, XEmacs converts characters with
+ − 1181 the 8th bit set into Meta characters. If @var{meta} is @code{nil},
+ − 1182 XEmacs disregards the 8th bit; this is necessary when the terminal uses
+ − 1183 it as a parity bit. If @var{meta} is neither @code{t} nor @code{nil},
+ − 1184 XEmacs uses all 8 bits of input unchanged. This is good for terminals
+ − 1185 using European 8-bit character sets.
+ − 1186
+ − 1187 @c Emacs 19 feature
+ − 1188 If @var{quit-char} is non-@code{nil}, it specifies the character to
+ − 1189 use for quitting. Normally this character is @kbd{C-g}.
+ − 1190 @xref{Quitting}.
+ − 1191 @end defun
+ − 1192
+ − 1193 The @code{current-input-mode} function returns the input mode settings
+ − 1194 XEmacs is currently using.
+ − 1195
+ − 1196 @c Emacs 19 feature
444
+ − 1197 @defun current-input-mode &optional console
428
+ − 1198 This function returns current mode for reading keyboard input. It
+ − 1199 returns a list, corresponding to the arguments of @code{set-input-mode},
+ − 1200 of the form @code{(@var{interrupt} @var{flow} @var{meta} @var{quit})} in
+ − 1201 which:
+ − 1202 @table @var
+ − 1203 @item interrupt
+ − 1204 is non-@code{nil} when XEmacs is using interrupt-driven input. If
+ − 1205 @code{nil}, Emacs is using @sc{cbreak} mode.
+ − 1206 @item flow
+ − 1207 is non-@code{nil} if XEmacs uses @sc{xon/xoff} (@kbd{C-q}, @kbd{C-s})
+ − 1208 flow control for output to the terminal. This value has no effect
+ − 1209 unless @var{interrupt} is non-@code{nil}.
+ − 1210 @item meta
+ − 1211 is @code{t} if XEmacs treats the eighth bit of input characters as
+ − 1212 the meta bit; @code{nil} means XEmacs clears the eighth bit of every
+ − 1213 input character; any other value means XEmacs uses all eight bits as the
+ − 1214 basic character code.
+ − 1215 @item quit
+ − 1216 is the character XEmacs currently uses for quitting, usually @kbd{C-g}.
+ − 1217 @end table
+ − 1218 @end defun
+ − 1219
+ − 1220 @node Translating Input
+ − 1221 @subsection Translating Input Events
+ − 1222 @cindex translating input events
+ − 1223
+ − 1224 This section describes features for translating input events into other
+ − 1225 input events before they become part of key sequences.
+ − 1226
+ − 1227 @ignore Not in XEmacs yet.
+ − 1228 @c Emacs 19 feature
+ − 1229 @defvar extra-keyboard-modifiers
+ − 1230 This variable lets Lisp programs ``press'' the modifier keys on the
+ − 1231 keyboard. The value is a bit mask:
+ − 1232
+ − 1233 @table @asis
+ − 1234 @item 1
+ − 1235 The @key{SHIFT} key.
+ − 1236 @item 2
+ − 1237 The @key{LOCK} key.
+ − 1238 @item 4
+ − 1239 The @key{CTL} key.
+ − 1240 @item 8
+ − 1241 The @key{META} key.
+ − 1242 @end table
+ − 1243
+ − 1244 Each time the user types a keyboard key, it is altered as if the
+ − 1245 modifier keys specified in the bit mask were held down.
+ − 1246
+ − 1247 When using X windows, the program can ``press'' any of the modifier
+ − 1248 keys in this way. Otherwise, only the @key{CTL} and @key{META} keys can
+ − 1249 be virtually pressed.
+ − 1250 @end defvar
+ − 1251
+ − 1252 @defvar keyboard-translate-table
+ − 1253 This variable is the translate table for keyboard characters. It lets
+ − 1254 you reshuffle the keys on the keyboard without changing any command
+ − 1255 bindings. Its value must be a string or @code{nil}.
+ − 1256
+ − 1257 If @code{keyboard-translate-table} is a string, then each character read
+ − 1258 from the keyboard is looked up in this string and the character in the
+ − 1259 string is used instead. If the string is of length @var{n}, character codes
+ − 1260 @var{n} and up are untranslated.
+ − 1261
+ − 1262 In the example below, we set @code{keyboard-translate-table} to a
+ − 1263 string of 128 characters. Then we fill it in to swap the characters
+ − 1264 @kbd{C-s} and @kbd{C-\} and the characters @kbd{C-q} and @kbd{C-^}.
+ − 1265 Subsequently, typing @kbd{C-\} has all the usual effects of typing
+ − 1266 @kbd{C-s}, and vice versa. (@xref{Flow Control} for more information on
+ − 1267 this subject.)
+ − 1268
+ − 1269 @cindex flow control example
+ − 1270 @example
+ − 1271 @group
+ − 1272 (defun evade-flow-control ()
+ − 1273 "Replace C-s with C-\ and C-q with C-^."
+ − 1274 (interactive)
+ − 1275 @end group
+ − 1276 @group
+ − 1277 (let ((the-table (make-string 128 0)))
+ − 1278 (let ((i 0))
+ − 1279 (while (< i 128)
+ − 1280 (aset the-table i i)
+ − 1281 (setq i (1+ i))))
+ − 1282 @end group
+ − 1283 ;; @r{Swap @kbd{C-s} and @kbd{C-\}.}
+ − 1284 (aset the-table ?\034 ?\^s)
+ − 1285 (aset the-table ?\^s ?\034)
+ − 1286 @group
+ − 1287 ;; @r{Swap @kbd{C-q} and @kbd{C-^}.}
+ − 1288 (aset the-table ?\036 ?\^q)
+ − 1289 (aset the-table ?\^q ?\036)
+ − 1290 (setq keyboard-translate-table the-table)))
+ − 1291 @end group
+ − 1292 @end example
+ − 1293
+ − 1294 Note that this translation is the first thing that happens to a
+ − 1295 character after it is read from the terminal. Record-keeping features
+ − 1296 such as @code{recent-keys} and dribble files record the characters after
+ − 1297 translation.
+ − 1298 @end defvar
+ − 1299
444
+ − 1300 @defun keyboard-translate &rest pairs
428
+ − 1301 This function modifies @code{keyboard-translate-table} to translate
+ − 1302 character code @var{from} into character code @var{to}. It creates
444
+ − 1303 or enlarges the translate table if necessary. Multiple
+ − 1304 @var{from}-@var{to} pairs may be specified.
428
+ − 1305 @end defun
+ − 1306 @end ignore
+ − 1307
+ − 1308 @defvar function-key-map
+ − 1309 This variable holds a keymap that describes the character sequences
+ − 1310 sent by function keys on an ordinary character terminal. This keymap
+ − 1311 uses the same data structure as other keymaps, but is used differently: it
+ − 1312 specifies translations to make while reading events.
+ − 1313
+ − 1314 If @code{function-key-map} ``binds'' a key sequence @var{k} to a vector
+ − 1315 @var{v}, then when @var{k} appears as a subsequence @emph{anywhere} in a
+ − 1316 key sequence, it is replaced with the events in @var{v}.
+ − 1317
+ − 1318 For example, VT100 terminals send @kbd{@key{ESC} O P} when the
+ − 1319 keypad PF1 key is pressed. Therefore, we want XEmacs to translate
+ − 1320 that sequence of events into the single event @code{pf1}. We accomplish
+ − 1321 this by ``binding'' @kbd{@key{ESC} O P} to @code{[pf1]} in
+ − 1322 @code{function-key-map}, when using a VT100.
+ − 1323
+ − 1324 Thus, typing @kbd{C-c @key{PF1}} sends the character sequence @kbd{C-c
+ − 1325 @key{ESC} O P}; later the function @code{read-key-sequence} translates
+ − 1326 this back into @kbd{C-c @key{PF1}}, which it returns as the vector
+ − 1327 @code{[?\C-c pf1]}.
+ − 1328
+ − 1329 Entries in @code{function-key-map} are ignored if they conflict with
+ − 1330 bindings made in the minor mode, local, or global keymaps. The intent
+ − 1331 is that the character sequences that function keys send should not have
+ − 1332 command bindings in their own right.
+ − 1333
+ − 1334 The value of @code{function-key-map} is usually set up automatically
+ − 1335 according to the terminal's Terminfo or Termcap entry, but sometimes
+ − 1336 those need help from terminal-specific Lisp files. XEmacs comes with
+ − 1337 terminal-specific files for many common terminals; their main purpose is
+ − 1338 to make entries in @code{function-key-map} beyond those that can be
+ − 1339 deduced from Termcap and Terminfo. @xref{Terminal-Specific}.
+ − 1340
+ − 1341 Emacs versions 18 and earlier used totally different means of detecting
+ − 1342 the character sequences that represent function keys.
+ − 1343 @end defvar
+ − 1344
+ − 1345 @defvar key-translation-map
+ − 1346 This variable is another keymap used just like @code{function-key-map}
+ − 1347 to translate input events into other events. It differs from
+ − 1348 @code{function-key-map} in two ways:
+ − 1349
+ − 1350 @itemize @bullet
+ − 1351 @item
+ − 1352 @code{key-translation-map} goes to work after @code{function-key-map} is
+ − 1353 finished; it receives the results of translation by
+ − 1354 @code{function-key-map}.
+ − 1355
+ − 1356 @item
+ − 1357 @code{key-translation-map} overrides actual key bindings.
+ − 1358 @end itemize
+ − 1359
+ − 1360 The intent of @code{key-translation-map} is for users to map one
+ − 1361 character set to another, including ordinary characters normally bound
+ − 1362 to @code{self-insert-command}.
+ − 1363 @end defvar
+ − 1364
+ − 1365 @cindex key translation function
+ − 1366 You can use @code{function-key-map} or @code{key-translation-map} for
+ − 1367 more than simple aliases, by using a function, instead of a key
+ − 1368 sequence, as the ``translation'' of a key. Then this function is called
+ − 1369 to compute the translation of that key.
+ − 1370
+ − 1371 The key translation function receives one argument, which is the prompt
+ − 1372 that was specified in @code{read-key-sequence}---or @code{nil} if the
+ − 1373 key sequence is being read by the editor command loop. In most cases
+ − 1374 you can ignore the prompt value.
+ − 1375
+ − 1376 If the function reads input itself, it can have the effect of altering
+ − 1377 the event that follows. For example, here's how to define @kbd{C-c h}
+ − 1378 to turn the character that follows into a Hyper character:
+ − 1379
+ − 1380 @example
+ − 1381 @group
+ − 1382 (defun hyperify (prompt)
+ − 1383 (let ((e (read-event)))
+ − 1384 (vector (if (numberp e)
+ − 1385 (logior (lsh 1 20) e)
+ − 1386 (if (memq 'hyper (event-modifiers e))
+ − 1387 e
+ − 1388 (add-event-modifier "H-" e))))))
+ − 1389
+ − 1390 (defun add-event-modifier (string e)
+ − 1391 (let ((symbol (if (symbolp e) e (car e))))
+ − 1392 (setq symbol (intern (concat string
+ − 1393 (symbol-name symbol))))
+ − 1394 @end group
+ − 1395 @group
+ − 1396 (if (symbolp e)
+ − 1397 symbol
+ − 1398 (cons symbol (cdr e)))))
+ − 1399
+ − 1400 (define-key function-key-map "\C-ch" 'hyperify)
+ − 1401 @end group
+ − 1402 @end example
+ − 1403
+ − 1404 @pindex iso-transl
+ − 1405 @cindex Latin-1 character set (input)
+ − 1406 @cindex ISO Latin-1 characters (input)
+ − 1407 The @file{iso-transl} library uses this feature to provide a way of
+ − 1408 inputting non-ASCII Latin-1 characters.
+ − 1409
+ − 1410 @node Recording Input
+ − 1411 @subsection Recording Input
+ − 1412
+ − 1413 @defun recent-keys &optional number
+ − 1414 This function returns a vector containing recent input events from the
+ − 1415 keyboard or mouse. By default, 100 events are recorded, which is how
+ − 1416 many @code{recent-keys} returns.
+ − 1417
+ − 1418 All input events are included, whether or not they were used as parts of
+ − 1419 key sequences. Thus, you always get the last 100 inputs, not counting
+ − 1420 keyboard macros. (Events from keyboard macros are excluded because they
+ − 1421 are less interesting for debugging; it should be enough to see the
+ − 1422 events that invoked the macros.)
+ − 1423
+ − 1424 If @var{number} is specified, not more than @var{number} events will be
+ − 1425 returned. You may change the number of stored events using
+ − 1426 @code{set-recent-keys-ring-size}.
+ − 1427 @end defun
+ − 1428
+ − 1429 @defun recent-keys-ring-size
+ − 1430 This function returns the number of recent events stored internally.
+ − 1431 This is also the maximum number of events @code{recent-keys} can
+ − 1432 return. By default, 100 events are stored.
+ − 1433 @end defun
+ − 1434
+ − 1435 @defun set-recent-keys-ring-size size
444
+ − 1436 This function changes the number of events stored by XEmacs and returned
428
+ − 1437 by @code{recent-keys}.
+ − 1438
+ − 1439 For example, @code{(set-recent-keys-ring-size 250)} will make XEmacs
+ − 1440 remember last 250 events and will make @code{recent-keys} return last
+ − 1441 250 events by default.
+ − 1442 @end defun
+ − 1443
444
+ − 1444 @deffn Command open-dribble-file filename
428
+ − 1445 @cindex dribble file
+ − 1446 This function opens a @dfn{dribble file} named @var{filename}. When a
+ − 1447 dribble file is open, each input event from the keyboard or mouse (but
+ − 1448 not those from keyboard macros) is written in that file. A
+ − 1449 non-character event is expressed using its printed representation
+ − 1450 surrounded by @samp{<@dots{}>}.
+ − 1451
+ − 1452 You close the dribble file by calling this function with an argument
+ − 1453 of @code{nil}.
+ − 1454
+ − 1455 This function is normally used to record the input necessary to
+ − 1456 trigger an XEmacs bug, for the sake of a bug report.
+ − 1457
+ − 1458 @example
+ − 1459 @group
+ − 1460 (open-dribble-file "~/dribble")
+ − 1461 @result{} nil
+ − 1462 @end group
+ − 1463 @end example
+ − 1464 @end deffn
+ − 1465
+ − 1466 See also the @code{open-termscript} function (@pxref{Terminal Output}).
+ − 1467
+ − 1468 @node Terminal Output
+ − 1469 @section Terminal Output
+ − 1470 @cindex terminal output
+ − 1471
+ − 1472 The terminal output functions send output to the terminal or keep
+ − 1473 track of output sent to the terminal. The function
+ − 1474 @code{device-baud-rate} tells you what XEmacs thinks is the output speed
+ − 1475 of the terminal.
+ − 1476
+ − 1477 @defun device-baud-rate &optional device
+ − 1478 This function's value is the output speed of the terminal associated
+ − 1479 with @var{device}, as far as XEmacs knows. @var{device} defaults to the
+ − 1480 selected device (usually the only device) if omitted. Changing this
+ − 1481 value does not change the speed of actual data transmission, but the
+ − 1482 value is used for calculations such as padding. This value has no
+ − 1483 effect for window-system devices. (This is different in FSF Emacs, where
+ − 1484 the baud rate also affects decisions about whether to scroll part of the
+ − 1485 screen or repaint, even when using a window system.)
+ − 1486
+ − 1487 The value is measured in bits per second.
+ − 1488 @end defun
+ − 1489
+ − 1490 XEmacs attempts to automatically initialize the baud rate by querying
+ − 1491 the terminal. If you are running across a network, however, and
+ − 1492 different parts of the network work are at different baud rates, the
+ − 1493 value returned by XEmacs may be different from the value used by your
+ − 1494 local terminal. Some network protocols communicate the local terminal
+ − 1495 speed to the remote machine, so that XEmacs and other programs can get
+ − 1496 the proper value, but others do not. If XEmacs has the wrong value, it
+ − 1497 makes decisions that are less than optimal. To fix the problem, use
+ − 1498 @code{set-device-baud-rate}.
+ − 1499
444
+ − 1500 @defun set-device-baud-rate device baud-rate
428
+ − 1501 This function sets the output speed of @var{device}. See
+ − 1502 @code{device-baud-rate}. @var{device} defaults to the selected device
444
+ − 1503 (usually the only device) if @code{nil}.
428
+ − 1504 @end defun
+ − 1505
+ − 1506 @defun send-string-to-terminal char-or-string &optional stdout-p device
+ − 1507 This function sends @var{char-or-string} to the terminal without
+ − 1508 alteration. Control characters in @var{char-or-string} have
+ − 1509 terminal-dependent effects.
+ − 1510
+ − 1511 If @var{device} is @code{nil}, this function writes to XEmacs's
+ − 1512 stderr, or to stdout if @var{stdout-p} is non-@code{nil}. Otherwise,
+ − 1513 @var{device} should be a tty or stream device, and the function writes
+ − 1514 to the device's normal or error output, according to @var{stdout-p}.
+ − 1515
+ − 1516 One use of this function is to define function keys on terminals that
+ − 1517 have downloadable function key definitions. For example, this is how on
+ − 1518 certain terminals to define function key 4 to move forward four
+ − 1519 characters (by transmitting the characters @kbd{C-u C-f} to the
+ − 1520 computer):
+ − 1521
+ − 1522 @example
+ − 1523 @group
+ − 1524 (send-string-to-terminal "\eF4\^U\^F")
+ − 1525 @result{} nil
+ − 1526 @end group
+ − 1527 @end example
+ − 1528 @end defun
+ − 1529
+ − 1530 @deffn Command open-termscript filename
+ − 1531 @cindex termscript file
+ − 1532 This function is used to open a @dfn{termscript file} that will record
+ − 1533 all the characters sent by XEmacs to the terminal. (If there are
+ − 1534 multiple tty or stream devices, all characters sent to all such devices
+ − 1535 are recorded.) The function returns @code{nil}. Termscript files are
+ − 1536 useful for investigating problems where XEmacs garbles the screen,
+ − 1537 problems that are due to incorrect Termcap entries or to undesirable
+ − 1538 settings of terminal options more often than to actual XEmacs bugs.
+ − 1539 Once you are certain which characters were actually output, you can
+ − 1540 determine reliably whether they correspond to the Termcap specifications
+ − 1541 in use.
+ − 1542
+ − 1543 A @code{nil} value for @var{filename} stops recording terminal output.
+ − 1544
+ − 1545 See also @code{open-dribble-file} in @ref{Terminal Input}.
+ − 1546
+ − 1547 @example
+ − 1548 @group
+ − 1549 (open-termscript "../junk/termscript")
+ − 1550 @result{} nil
+ − 1551 @end group
+ − 1552 @end example
+ − 1553 @end deffn
+ − 1554
+ − 1555 @ignore Not in XEmacs
+ − 1556 @node Special Keysyms
+ − 1557 @section System-Specific X11 Keysyms
+ − 1558
+ − 1559 To define system-specific X11 keysyms, set the variable
+ − 1560 @code{system-key-alist}.
+ − 1561
+ − 1562 @defvar system-key-alist
+ − 1563 This variable's value should be an alist with one element for each
+ − 1564 system-specific keysym. An element has this form: @code{(@var{code}
+ − 1565 . @var{symbol})}, where @var{code} is the numeric keysym code (not
+ − 1566 including the ``vendor specific'' bit, 1 << 28), and @var{symbol} is the
+ − 1567 name for the function key.
+ − 1568
+ − 1569 For example @code{(168 . mute-acute)} defines a system-specific key used
+ − 1570 by HP X servers whose numeric code is (1 << 28) + 168.
+ − 1571
+ − 1572 It is not a problem if the alist defines keysyms for other X servers, as
+ − 1573 long as they don't conflict with the ones used by the X server actually
+ − 1574 in use.
+ − 1575
+ − 1576 The variable is always local to the current X terminal and cannot be
+ − 1577 buffer-local. @xref{Multiple Displays}.
+ − 1578 @end defvar
+ − 1579 @end ignore
+ − 1580
+ − 1581 @node Flow Control
+ − 1582 @section Flow Control
+ − 1583 @cindex flow control characters
+ − 1584
+ − 1585 This section attempts to answer the question ``Why does XEmacs choose
+ − 1586 to use flow-control characters in its command character set?'' For a
+ − 1587 second view on this issue, read the comments on flow control in the
+ − 1588 @file{emacs/INSTALL} file from the distribution; for help with Termcap
+ − 1589 entries and DEC terminal concentrators, see @file{emacs/etc/TERMS}.
+ − 1590
+ − 1591 @cindex @kbd{C-s}
+ − 1592 @cindex @kbd{C-q}
+ − 1593 At one time, most terminals did not need flow control, and none used
+ − 1594 @code{C-s} and @kbd{C-q} for flow control. Therefore, the choice of
+ − 1595 @kbd{C-s} and @kbd{C-q} as command characters was uncontroversial.
+ − 1596 XEmacs, for economy of keystrokes and portability, used nearly all the
+ − 1597 @sc{ascii} control characters, with mnemonic meanings when possible;
+ − 1598 thus, @kbd{C-s} for search and @kbd{C-q} for quote.
+ − 1599
+ − 1600 Later, some terminals were introduced which required these characters
+ − 1601 for flow control. They were not very good terminals for full-screen
+ − 1602 editing, so XEmacs maintainers did not pay attention. In later years,
+ − 1603 flow control with @kbd{C-s} and @kbd{C-q} became widespread among
+ − 1604 terminals, but by this time it was usually an option. And the majority
+ − 1605 of users, who can turn flow control off, were unwilling to switch to
+ − 1606 less mnemonic key bindings for the sake of flow control.
+ − 1607
+ − 1608 So which usage is ``right'', XEmacs's or that of some terminal and
+ − 1609 concentrator manufacturers? This question has no simple answer.
+ − 1610
+ − 1611 One reason why we are reluctant to cater to the problems caused by
+ − 1612 @kbd{C-s} and @kbd{C-q} is that they are gratuitous. There are other
+ − 1613 techniques (albeit less common in practice) for flow control that
+ − 1614 preserve transparency of the character stream. Note also that their use
+ − 1615 for flow control is not an official standard. Interestingly, on the
+ − 1616 model 33 teletype with a paper tape punch (which is very old), @kbd{C-s}
+ − 1617 and @kbd{C-q} were sent by the computer to turn the punch on and off!
+ − 1618
+ − 1619 As X servers and other window systems replace character-only
+ − 1620 terminals, this problem is gradually being cured. For the mean time,
+ − 1621 XEmacs provides a convenient way of enabling flow control if you want it:
+ − 1622 call the function @code{enable-flow-control}.
+ − 1623
444
+ − 1624 @deffn Command enable-flow-control &optional argument
428
+ − 1625 This function enables use of @kbd{C-s} and @kbd{C-q} for output flow
+ − 1626 control, and provides the characters @kbd{C-\} and @kbd{C-^} as aliases
+ − 1627 for them using @code{keyboard-translate-table} (@pxref{Translating Input}).
444
+ − 1628
+ − 1629 With optional argument @var{argument} (interactively the prefix
+ − 1630 argument), enable flow control mode if @var{argument} is positive; else
+ − 1631 disable it.
+ − 1632 @end deffn
428
+ − 1633
+ − 1634 You can use the function @code{enable-flow-control-on} in your
+ − 1635 @file{.emacs} file to enable flow control automatically on certain
+ − 1636 terminal types.
+ − 1637
+ − 1638 @defun enable-flow-control-on &rest termtypes
+ − 1639 This function enables flow control, and the aliases @kbd{C-\} and @kbd{C-^},
+ − 1640 if the terminal type is one of @var{termtypes}. For example:
+ − 1641
+ − 1642 @smallexample
+ − 1643 (enable-flow-control-on "vt200" "vt300" "vt101" "vt131")
+ − 1644 @end smallexample
+ − 1645 @end defun
+ − 1646
+ − 1647 Here is how @code{enable-flow-control} does its job:
+ − 1648
+ − 1649 @enumerate
+ − 1650 @item
+ − 1651 @cindex @sc{cbreak}
+ − 1652 It sets @sc{cbreak} mode for terminal input, and tells the operating
+ − 1653 system to handle flow control, with @code{(set-input-mode nil t)}.
+ − 1654
+ − 1655 @item
+ − 1656 It sets up @code{keyboard-translate-table} to translate @kbd{C-\} and
+ − 1657 @kbd{C-^} into @kbd{C-s} and @kbd{C-q}. Except at its very
+ − 1658 lowest level, XEmacs never knows that the characters typed were anything
+ − 1659 but @kbd{C-s} and @kbd{C-q}, so you can in effect type them as @kbd{C-\}
+ − 1660 and @kbd{C-^} even when they are input for other commands.
+ − 1661 @xref{Translating Input}.
+ − 1662 @end enumerate
+ − 1663
+ − 1664 If the terminal is the source of the flow control characters, then once
+ − 1665 you enable kernel flow control handling, you probably can make do with
+ − 1666 less padding than normal for that terminal. You can reduce the amount
+ − 1667 of padding by customizing the Termcap entry. You can also reduce it by
+ − 1668 setting @code{baud-rate} to a smaller value so that XEmacs uses a smaller
+ − 1669 speed when calculating the padding needed. @xref{Terminal Output}.
+ − 1670
+ − 1671 @node Batch Mode
+ − 1672 @section Batch Mode
+ − 1673 @cindex batch mode
+ − 1674 @cindex noninteractive use
+ − 1675
+ − 1676 The command line option @samp{-batch} causes XEmacs to run
+ − 1677 noninteractively. In this mode, XEmacs does not read commands from the
+ − 1678 terminal, it does not alter the terminal modes, and it does not expect
+ − 1679 to be outputting to an erasable screen. The idea is that you specify
+ − 1680 Lisp programs to run; when they are finished, XEmacs should exit. The
+ − 1681 way to specify the programs to run is with @samp{-l @var{file}}, which
+ − 1682 loads the library named @var{file}, and @samp{-f @var{function}}, which
+ − 1683 calls @var{function} with no arguments.
+ − 1684
+ − 1685 Any Lisp program output that would normally go to the echo area,
+ − 1686 either using @code{message} or using @code{prin1}, etc., with @code{t}
+ − 1687 as the stream, goes instead to XEmacs's standard error descriptor when
+ − 1688 in batch mode. Thus, XEmacs behaves much like a noninteractive
+ − 1689 application program. (The echo area output that XEmacs itself normally
+ − 1690 generates, such as command echoing, is suppressed entirely.)
+ − 1691
+ − 1692 @defun noninteractive
+ − 1693 This function returns non-@code{nil} when XEmacs is running in batch mode.
+ − 1694 @end defun
+ − 1695
+ − 1696 @defvar noninteractive
+ − 1697 This variable is non-@code{nil} when XEmacs is running in batch mode.
+ − 1698 Setting this variable to @code{nil}, however, will not change whether
+ − 1699 XEmacs is running in batch mode, and will not change the return value
+ − 1700 of the @code{noninteractive} function.
+ − 1701 @end defvar