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1 | @c -*-texinfo-*- |
2 | @c This is part of the GNU Emacs Lisp Reference Manual. | |
3 | @c Copyright (C) 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc. | |
4 | @c See the file elisp.texi for copying conditions. | |
5 | @setfilename ../info/os | |
6 | @node System Interface, Display, 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 Emacs}, 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 Emacs 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 | * Timers:: Setting a timer to call a function at a certain time. | |
24 | * Terminal Input:: Recording terminal input for debugging. | |
25 | * Terminal Output:: Recording terminal output for debugging. | |
26 | * Special Keysyms:: Defining system-specific key symbols for X windows. | |
27 | * Flow Control:: How to turn output flow control on or off. | |
28 | * Batch Mode:: Running Emacs without terminal interaction. | |
29 | @end menu | |
30 | ||
31 | @node Starting Up | |
32 | @section Starting Up Emacs | |
33 | ||
34 | This section describes what Emacs does when it is started, and how you | |
35 | can customize these actions. | |
36 | ||
37 | @menu | |
38 | * Start-up Summary:: Sequence of actions Emacs performs at start-up. | |
39 | * Init File:: Details on reading the init file (@file{.emacs}). | |
40 | * Terminal-Specific:: How the terminal-specific Lisp file is read. | |
41 | * Command Line Arguments:: How command line arguments are processed, | |
42 | and how you can customize them. | |
43 | @end menu | |
44 | ||
45 | @node Start-up Summary | |
46 | @subsection Summary: Sequence of Actions at Start Up | |
47 | @cindex initialization | |
48 | @cindex start up of Emacs | |
49 | @cindex @file{startup.el} | |
50 | ||
51 | The order of operations performed (in @file{startup.el}) by Emacs when | |
52 | it is started up is as follows: | |
53 | ||
54 | @enumerate | |
55 | @item | |
56 | It loads the initialization library for the window system, if you are | |
57 | using a window system. This library's name is | |
58 | @file{term/@var{windowsystem}-win.el}. | |
59 | ||
60 | @item | |
61 | It initializes the X window frame and faces, if appropriate. | |
62 | ||
63 | @item | |
64 | It runs the normal hook @code{before-init-hook}. | |
65 | ||
66 | @item | |
67 | It loads the library @file{site-start}, unless the option | |
68 | @samp{-no-site-file} was specified. The library's file name is usually | |
69 | @file{site-start.el}. | |
70 | @cindex @file{site-start.el} | |
71 | ||
72 | @item | |
73 | It loads the file @file{~/.emacs} unless @samp{-q} was specified on | |
74 | command line. (This is not done in @samp{-batch} mode.) The @samp{-u} | |
75 | option can specify the user name whose home directory should be used | |
76 | instead of @file{~}. | |
77 | ||
78 | @item | |
79 | It loads the library @file{default} unless @code{inhibit-default-init} | |
80 | is non-@code{nil}. (This is not done in @samp{-batch} mode or if | |
81 | @samp{-q} was specified on command line.) The library's file name is | |
82 | usually @file{default.el}. | |
83 | @cindex @file{default.el} | |
84 | ||
85 | @item | |
86 | It runs the normal hook @code{after-init-hook}. | |
87 | ||
88 | @item | |
89 | It sets the major mode according to @code{initial-major-mode}, provided | |
90 | the buffer @samp{*scratch*} is still current and still in Fundamental | |
91 | mode. | |
92 | ||
93 | @item | |
94 | It loads the terminal-specific Lisp file, if any, except when in batch | |
95 | mode or using a window system. | |
96 | ||
97 | @item | |
98 | It displays the initial echo area message, unless you have suppressed | |
99 | that with @code{inhibit-startup-echo-area-message}. | |
100 | ||
101 | @item | |
102 | It processes any remaining command line arguments. | |
103 | ||
104 | @item | |
105 | It runs @code{term-setup-hook}. | |
106 | ||
107 | @item | |
108 | It calls @code{frame-notice-user-settings}, which modifies the | |
109 | parameters of the selected frame according to whatever the init files | |
110 | specify. | |
111 | ||
112 | @item | |
113 | It runs @code{window-setup-hook}. @xref{Window Systems}. | |
114 | ||
115 | @item | |
116 | It displays copyleft, nonwarranty and basic use information, provided | |
117 | there were no remaining command line arguments (a few steps above) and | |
118 | the value of @code{inhibit-startup-message} is @code{nil}. | |
119 | @end enumerate | |
120 | ||
121 | @defopt inhibit-startup-message | |
122 | This variable inhibits the initial startup messages (the nonwarranty, | |
123 | etc.). If it is non-@code{nil}, then the messages are not printed. | |
124 | ||
125 | This variable exists so you can set it in your personal init file, once | |
126 | you are familiar with the contents of the startup message. Do not set | |
127 | this variable in the init file of a new user, or in a way that affects | |
128 | more than one user, because that would prevent new users from receiving | |
129 | the information they are supposed to see. | |
130 | @end defopt | |
131 | ||
132 | @defopt inhibit-startup-echo-area-message | |
133 | This variable controls the display of the startup echo area message. | |
134 | You can suppress the startup echo area message by adding text with this | |
135 | form to your @file{.emacs} file: | |
136 | ||
137 | @example | |
138 | (setq inhibit-startup-echo-area-message | |
139 | "@var{your-login-name}") | |
140 | @end example | |
141 | ||
142 | Simply setting @code{inhibit-startup-echo-area-message} to your login | |
143 | name is not sufficient to inhibit the message; Emacs explicitly checks | |
144 | whether @file{.emacs} contains an expression as shown above. Your login | |
145 | name must appear in the expression as a Lisp string constant. | |
146 | ||
147 | This way, you can easily inhibit the message for yourself if you wish, | |
148 | but thoughtless copying of your @file{.emacs} file will not inhibit the | |
149 | message for someone else. | |
150 | @end defopt | |
151 | ||
152 | @node Init File | |
153 | @subsection The Init File: @file{.emacs} | |
154 | @cindex init file | |
155 | @cindex @file{.emacs} | |
156 | ||
157 | When you start Emacs, it normally attempts to load the file | |
158 | @file{.emacs} from your home directory. This file, if it exists, must | |
159 | contain Lisp code. It is called your @dfn{init file}. The command line | |
160 | switches @samp{-q} and @samp{-u} affect the use of the init file; | |
161 | @samp{-q} says not to load an init file, and @samp{-u} says to load a | |
a890e1b0 | 162 | specified user's init file instead of yours. @xref{Entering Emacs,,, |
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163 | emacs, The GNU Emacs Manual}. |
164 | ||
165 | @cindex default init file | |
166 | A site may have a @dfn{default init file}, which is the library named | |
167 | @file{default.el}. Emacs finds the @file{default.el} file through the | |
168 | standard search path for libraries (@pxref{How Programs Do Loading}). | |
169 | The Emacs distribution does not come with this file; sites may provide | |
170 | one for local customizations. If the default init file exists, it is | |
171 | loaded whenever you start Emacs, except in batch mode or if @samp{-q} is | |
172 | specified. But your own personal init file, if any, is loaded first; if | |
173 | it sets @code{inhibit-default-init} to a non-@code{nil} value, then | |
174 | Emacs does not subsequently load the @file{default.el} file. | |
175 | ||
176 | Another file for site-customization is @file{site-start.el}. Emacs | |
177 | loads this @emph{before} the user's init file. You can inhibit the | |
178 | loading of this file with the option @samp{-no-site-file}. | |
179 | ||
180 | If there is a great deal of code in your @file{.emacs} file, you | |
181 | should move it into another file named @file{@var{something}.el}, | |
182 | byte-compile it (@pxref{Byte Compilation}), and make your @file{.emacs} | |
183 | file load the other file using @code{load} (@pxref{Loading}). | |
184 | ||
a890e1b0 | 185 | @xref{Init File Examples,,, emacs, The GNU Emacs Manual}, for |
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186 | examples of how to make various commonly desired customizations in your |
187 | @file{.emacs} file. | |
188 | ||
189 | @defopt inhibit-default-init | |
190 | This variable prevents Emacs from loading the default initialization | |
191 | library file for your session of Emacs. If its value is non-@code{nil}, | |
192 | then the default library is not loaded. The default value is | |
193 | @code{nil}. | |
194 | @end defopt | |
195 | ||
196 | @defvar before-init-hook | |
197 | @defvarx after-init-hook | |
198 | These two normal hooks are run just before, and just after, loading of | |
199 | the user's init file, @file{default.el}, and/or @file{site-start.el}. | |
200 | @end defvar | |
201 | ||
202 | @node Terminal-Specific | |
203 | @subsection Terminal-Specific Initialization | |
204 | @cindex terminal-specific initialization | |
205 | ||
206 | Each terminal type can have its own Lisp library that Emacs loads when | |
207 | run on that type of terminal. For a terminal type named @var{termtype}, | |
208 | the library is called @file{term/@var{termtype}}. Emacs finds the file | |
209 | by searching the @code{load-path} directories as it does for other | |
210 | files, and trying the @samp{.elc} and @samp{.el} suffixes. Normally, | |
211 | terminal-specific Lisp library is located in @file{emacs/lisp/term}, a | |
212 | subdirectory of the @file{emacs/lisp} directory in which most Emacs Lisp | |
213 | libraries are kept.@refill | |
214 | ||
215 | The library's name is constructed by concatenating the value of the | |
216 | variable @code{term-file-prefix} and the terminal type. Normally, | |
217 | @code{term-file-prefix} has the value @code{"term/"}; changing this | |
218 | is not recommended. | |
219 | ||
220 | The usual function of a terminal-specific library is to enable special | |
221 | keys to send sequences that Emacs can recognize. It may also need to | |
222 | set or add to @code{function-key-map} if the Termcap entry does not | |
223 | specify all the terminal's function keys. @xref{Terminal Input}. | |
224 | ||
225 | @cindex Termcap | |
226 | When the name of the terminal type contains a hyphen, only the part of | |
227 | the name before the first hyphen is significant in choosing the library | |
228 | name. Thus, terminal types @samp{aaa-48} and @samp{aaa-30-rv} both use | |
229 | the @file{term/aaa} library. If necessary, the library can evaluate | |
230 | @code{(getenv "TERM")} to find the full name of the terminal | |
231 | type.@refill | |
232 | ||
233 | Your @file{.emacs} file can prevent the loading of the | |
234 | terminal-specific library by setting the variable | |
235 | @code{term-file-prefix} to @code{nil}. This feature is useful when | |
236 | experimenting with your own peculiar customizations. | |
237 | ||
238 | You can also arrange to override some of the actions of the | |
239 | terminal-specific library by setting the variable | |
240 | @code{term-setup-hook}. This is a normal hook which Emacs runs using | |
241 | @code{run-hooks} at the end of Emacs initialization, after loading both | |
242 | your @file{.emacs} file and any terminal-specific libraries. You can | |
243 | use this variable to define initializations for terminals that do not | |
244 | have their own libraries. @xref{Hooks}. | |
245 | ||
246 | @defvar term-file-prefix | |
247 | @cindex @code{TERM} environment variable | |
248 | If the @code{term-file-prefix} variable is non-@code{nil}, Emacs loads | |
249 | a terminal-specific initialization file as follows: | |
250 | ||
251 | @example | |
252 | (load (concat term-file-prefix (getenv "TERM"))) | |
253 | @end example | |
254 | ||
255 | @noindent | |
256 | You may set the @code{term-file-prefix} variable to @code{nil} in your | |
257 | @file{.emacs} file if you do not wish to load the | |
258 | terminal-initialization file. To do this, put the following in | |
259 | your @file{.emacs} file: @code{(setq term-file-prefix nil)}. | |
260 | @end defvar | |
261 | ||
262 | @defvar term-setup-hook | |
263 | This variable is a normal hook which Emacs runs after loading your | |
264 | @file{.emacs} file, the default initialization file (if any) and the | |
265 | terminal-specific Lisp file. | |
266 | ||
267 | You can use @code{term-setup-hook} to override the definitions made by a | |
268 | terminal-specific file. | |
269 | @end defvar | |
270 | ||
271 | See @code{window-setup-hook} in @ref{Window Systems}, for a related | |
272 | feature. | |
273 | ||
274 | @node Command Line Arguments | |
275 | @subsection Command Line Arguments | |
276 | @cindex command line arguments | |
277 | ||
278 | You can use command line arguments to request various actions when you | |
279 | start Emacs. Since you do not need to start Emacs more than once per | |
280 | day, and will often leave your Emacs session running longer than that, | |
281 | command line arguments are hardly ever used. As a practical matter, it | |
282 | is best to avoid making the habit of using them, since this habit would | |
283 | encourage you to kill and restart Emacs unnecessarily often. These | |
284 | options exist for two reasons: to be compatible with other editors (for | |
285 | invocation by other programs) and to enable shell scripts to run | |
286 | specific Lisp programs. | |
287 | ||
288 | This section describes how Emacs processes command line arguments, | |
289 | and how you can customize them. | |
290 | ||
291 | @ignore | |
292 | (Note that some other editors require you to start afresh each time | |
293 | you want to edit a file. With this kind of editor, you will probably | |
294 | specify the file as a command line argument. The recommended way to | |
295 | use GNU Emacs is to start it only once, just after you log in, and do | |
296 | all your editing in the same Emacs process. Each time you want to edit | |
297 | a different file, you visit it with the existing Emacs, which eventually | |
298 | comes to have many files in it ready for editing. Usually you do not | |
299 | kill the Emacs until you are about to log out.) | |
300 | @end ignore | |
301 | ||
302 | @defun command-line | |
303 | This function parses the command line which Emacs was called with, | |
304 | processes it, loads the user's @file{.emacs} file and displays the | |
305 | initial nonwarranty information, etc. | |
306 | @end defun | |
307 | ||
308 | @defvar command-line-processed | |
309 | The value of this variable is @code{t} once the command line has been | |
310 | processed. | |
311 | ||
312 | If you redump Emacs by calling @code{dump-emacs}, you may wish to set | |
313 | this variable to @code{nil} first in order to cause the new dumped Emacs | |
314 | to process its new command line arguments. | |
315 | @end defvar | |
316 | ||
317 | @defvar command-switch-alist | |
318 | @cindex switches on command line | |
319 | @cindex options on command line | |
320 | @cindex command line options | |
321 | The value of this variable is an alist of user-defined command-line | |
322 | options and associated handler functions. This variable exists so you | |
323 | can add elements to it. | |
324 | ||
325 | A @dfn{command line option} is an argument on the command line of the | |
326 | form: | |
327 | ||
328 | @example | |
329 | -@var{option} | |
330 | @end example | |
331 | ||
332 | The elements of the @code{command-switch-alist} look like this: | |
333 | ||
334 | @example | |
335 | (@var{option} . @var{handler-function}) | |
336 | @end example | |
337 | ||
338 | The @var{handler-function} is called to handle @var{option} and receives | |
339 | the option name as its sole argument. | |
340 | ||
341 | In some cases, the option is followed in the command line by an | |
342 | argument. In these cases, the @var{handler-function} can find all the | |
343 | remaining command-line arguments in the variable | |
344 | @code{command-line-args-left}. (The entire list of command-line | |
345 | arguments is in @code{command-line-args}.) | |
346 | ||
347 | The command line arguments are parsed by the @code{command-line-1} | |
348 | function in the @file{startup.el} file. See also @ref{Command | |
349 | Switches, , Command Line Switches and Arguments, emacs, The GNU Emacs | |
350 | Manual}. | |
351 | @end defvar | |
352 | ||
353 | @defvar command-line-args | |
354 | The value of this variable is the list of command line arguments passed | |
355 | to Emacs. | |
356 | @end defvar | |
357 | ||
358 | @defvar command-line-functions | |
359 | This variable's value is a list of functions for handling an | |
360 | unrecognized command-line argument. Each time the next argument to be | |
361 | processed has no special meaning, the functions in this list are called, | |
362 | in the order they appear, until one of them returns a non-@code{nil} | |
363 | value. | |
364 | ||
365 | These functions are called with no arguments. They can access the | |
366 | command-line argument under consideration through the variable | |
367 | @code{argi}. The remaining arguments (not including the current one) | |
368 | are in the variable @code{command-line-args-left}. | |
369 | ||
370 | When a function recognizes and processes the argument in @code{argi}, it | |
371 | should return a non-@code{nil} value to say it has dealt with that | |
372 | argument. If it has also dealt with some of the following arguments, it | |
373 | can indicate that by deleting them from @code{command-line-args-left}. | |
374 | ||
375 | If all of these functions return @code{nil}, then the argument is used | |
376 | as a file name to visit. | |
377 | @end defvar | |
378 | ||
379 | @node Getting Out | |
380 | @section Getting Out of Emacs | |
381 | @cindex exiting Emacs | |
382 | ||
383 | There are two ways to get out of Emacs: you can kill the Emacs job, | |
384 | which exits permanently, or you can suspend it, which permits you to | |
385 | reenter the Emacs process later. As a practical matter, you seldom kill | |
386 | Emacs---only when you are about to log out. Suspending is much more | |
387 | common. | |
388 | ||
389 | @menu | |
390 | * Killing Emacs:: Exiting Emacs irreversibly. | |
391 | * Suspending Emacs:: Exiting Emacs reversibly. | |
392 | @end menu | |
393 | ||
394 | @node Killing Emacs | |
395 | @comment node-name, next, previous, up | |
396 | @subsection Killing Emacs | |
397 | @cindex killing Emacs | |
398 | ||
399 | Killing Emacs means ending the execution of the Emacs process. The | |
400 | parent process normally resumes control. The low-level primitive for | |
401 | killing Emacs is @code{kill-emacs}. | |
402 | ||
403 | @defun kill-emacs &optional exit-data | |
404 | This function exits the Emacs process and kills it. | |
405 | ||
406 | If @var{exit-data} is an integer, then it is used as the exit status | |
407 | of the Emacs process. (This is useful primarily in batch operation; see | |
408 | @ref{Batch Mode}.) | |
409 | ||
410 | If @var{exit-data} is a string, its contents are stuffed into the | |
411 | terminal input buffer so that the shell (or whatever program next reads | |
412 | input) can read them. | |
413 | @end defun | |
414 | ||
415 | All the information in the Emacs process, aside from files that have | |
416 | been saved, is lost when the Emacs is killed. Because killing Emacs | |
417 | inadvertently can lose a lot of work, Emacs queries for confirmation | |
418 | before actually terminating if you have buffers that need saving or | |
419 | subprocesses that are running. This is done in the function | |
420 | @code{save-buffers-kill-emacs}. | |
421 | ||
422 | @defvar kill-emacs-query-functions | |
423 | After asking the standard questions, @code{save-buffers-kill-emacs} | |
424 | calls the functions in the list @code{kill-buffer-query-functions}, in | |
425 | order of appearance, with no arguments. These functions can ask for | |
426 | additional confirmation from the user. If any of them returns | |
427 | non-@code{nil}, Emacs is not killed. | |
428 | @end defvar | |
429 | ||
430 | @defvar kill-emacs-hook | |
431 | This variable is a normal hook; once @code{save-buffers-kill-emacs} is | |
432 | finished with all file saving and confirmation, it runs the functions in | |
433 | this hook. | |
434 | @end defvar | |
435 | ||
436 | @node Suspending Emacs | |
437 | @subsection Suspending Emacs | |
438 | @cindex suspending Emacs | |
439 | ||
440 | @dfn{Suspending Emacs} means stopping Emacs temporarily and returning | |
441 | control to its superior process, which is usually the shell. This | |
442 | allows you to resume editing later in the same Emacs process, with the | |
443 | same buffers, the same kill ring, the same undo history, and so on. To | |
444 | resume Emacs, use the appropriate command in the parent shell---most | |
445 | likely @code{fg}. | |
446 | ||
447 | Some operating systems do not support suspension of jobs; on these | |
448 | systems, ``suspension'' actually creates a new shell temporarily as a | |
449 | subprocess of Emacs. Then you would exit the shell to return to Emacs. | |
450 | ||
451 | Suspension is not useful with window systems such as X, because the | |
452 | Emacs job may not have a parent that can resume it again, and in any | |
453 | case you can give input to some other job such as a shell merely by | |
454 | moving to a different window. Therefore, suspending is not allowed | |
455 | when Emacs is an X client. | |
456 | ||
457 | @defun suspend-emacs string | |
458 | This function stops Emacs and returns control to the superior process. | |
459 | If and when the superior process resumes Emacs, @code{suspend-emacs} | |
460 | returns @code{nil} to its caller in Lisp. | |
461 | ||
462 | If @var{string} is non-@code{nil}, its characters are sent to be read | |
463 | as terminal input by Emacs's superior shell. The characters in | |
464 | @var{string} are not echoed by the superior shell; only the results | |
465 | appear. | |
466 | ||
467 | Before suspending, @code{suspend-emacs} runs the normal hook | |
468 | @code{suspend-hook}. In Emacs version 18, @code{suspend-hook} was not a | |
469 | normal hook; its value was a single function, and if its value was | |
470 | non-@code{nil}, then @code{suspend-emacs} returned immediately without | |
471 | actually suspending anything. | |
472 | ||
473 | After the user resumes Emacs, it runs the normal hook | |
474 | @code{suspend-resume-hook}. @xref{Hooks}. | |
475 | ||
476 | The next redisplay after resumption will redraw the entire screen, | |
477 | unless the variable @code{no-redraw-on-reenter} is non-@code{nil} | |
478 | (@pxref{Refresh Screen}). | |
479 | ||
480 | In the following example, note that @samp{pwd} is not echoed after | |
481 | Emacs is suspended. But it is read and executed by the shell. | |
482 | ||
483 | @smallexample | |
484 | @group | |
485 | (suspend-emacs) | |
486 | @result{} nil | |
487 | @end group | |
488 | ||
489 | @group | |
490 | (add-hook 'suspend-hook | |
491 | (function (lambda () | |
492 | (or (y-or-n-p | |
493 | "Really suspend? ") | |
494 | (error "Suspend cancelled"))))) | |
495 | @result{} (lambda nil | |
496 | (or (y-or-n-p "Really suspend? ") | |
497 | (error "Suspend cancelled"))) | |
498 | @end group | |
499 | @group | |
500 | (add-hook 'suspend-resume-hook | |
501 | (function (lambda () (message "Resumed!")))) | |
502 | @result{} (lambda nil (message "Resumed!")) | |
503 | @end group | |
504 | @group | |
505 | (suspend-emacs "pwd") | |
506 | @result{} nil | |
507 | @end group | |
508 | @group | |
509 | ---------- Buffer: Minibuffer ---------- | |
510 | Really suspend? @kbd{y} | |
511 | ---------- Buffer: Minibuffer ---------- | |
512 | @end group | |
513 | ||
514 | @group | |
515 | ---------- Parent Shell ---------- | |
516 | lewis@@slug[23] % /user/lewis/manual | |
517 | lewis@@slug[24] % fg | |
518 | @end group | |
519 | ||
520 | @group | |
521 | ---------- Echo Area ---------- | |
522 | Resumed! | |
523 | @end group | |
524 | @end smallexample | |
525 | @end defun | |
526 | ||
527 | @defvar suspend-hook | |
528 | This variable is a normal hook run before suspending. | |
529 | @end defvar | |
530 | ||
531 | @defvar suspend-resume-hook | |
532 | This variable is a normal hook run after suspending. | |
533 | @end defvar | |
534 | ||
535 | @node System Environment | |
536 | @section Operating System Environment | |
537 | @cindex operating system environment | |
538 | ||
539 | Emacs provides access to variables in the operating system environment | |
540 | through various functions. These variables include the name of the | |
541 | system, the user's @sc{uid}, and so on. | |
542 | ||
543 | @defvar system-type | |
544 | The value of this variable is a symbol indicating the type of | |
545 | operating system Emacs is operating on. Here is a table of the symbols | |
546 | for the operating systems that Emacs can run on up to version 19.1. | |
547 | ||
548 | @table @code | |
549 | @item aix-v3 | |
550 | AIX. | |
551 | ||
552 | @item berkeley-unix | |
553 | Berkeley BSD. | |
554 | ||
555 | @item hpux | |
556 | Hewlett-Packard operating system. | |
557 | ||
558 | @item irix | |
559 | Silicon Graphics Irix system. | |
560 | ||
561 | @item rtu | |
562 | Masscomp RTU, UCB universe. | |
563 | ||
564 | @item unisoft-unix | |
565 | UniSoft UniPlus. | |
566 | ||
567 | @item usg-unix-v | |
568 | AT&T System V. | |
569 | ||
570 | @item vax-vms | |
571 | VAX VMS. | |
572 | ||
573 | @item xenix | |
574 | SCO Xenix 386. | |
575 | @end table | |
576 | ||
577 | We do not wish to add new symbols to make finer distinctions unless it | |
578 | is absolutely necessary! In fact, we hope to eliminate some of these | |
579 | alternatives in the future. We recommend using | |
580 | @code{system-configuration} to distinguish between different operating | |
581 | systems. | |
582 | @end defvar | |
583 | ||
584 | @defvar system-configuration | |
585 | This variable holds the three-part configuration name for the | |
586 | hardware/software configuration of your system, as a string. The | |
587 | convenient way to test parts of this string is with @code{string-match}. | |
588 | @end defvar | |
589 | ||
590 | @defun system-name | |
591 | This function returns the name of the machine you are running on. | |
592 | @example | |
593 | (system-name) | |
594 | @result{} "prep.ai.mit.edu" | |
595 | @end example | |
596 | @end defun | |
597 | ||
598 | @defun getenv var | |
599 | @cindex environment variable access | |
600 | This function returns the value of the environment variable @var{var}, | |
601 | as a string. Within Emacs, the environment variable values are kept in | |
602 | the Lisp variable @code{process-environment}. | |
603 | ||
604 | @example | |
605 | @group | |
606 | (getenv "USER") | |
607 | @result{} "lewis" | |
608 | @end group | |
609 | ||
610 | @group | |
611 | lewis@@slug[10] % printenv | |
612 | PATH=.:/user/lewis/bin:/usr/bin:/usr/local/bin | |
613 | USER=lewis | |
614 | @end group | |
615 | @group | |
616 | TERM=ibmapa16 | |
617 | SHELL=/bin/csh | |
618 | HOME=/user/lewis | |
619 | @end group | |
620 | @end example | |
621 | @end defun | |
622 | ||
623 | @c Emacs 19 feature | |
624 | @deffn Command setenv variable value | |
625 | This command sets the value of the environment variable named | |
626 | @var{variable} to @var{value}. Both arguments should be strings. This | |
627 | function works by modifying @code{process-environment}; binding that | |
628 | variable with @code{let} is also reasonable practice. | |
629 | @end deffn | |
630 | ||
631 | @defvar process-environment | |
632 | This variable is a list of strings, each describing one environment | |
633 | variable. The functions @code{getenv} and @code{setenv} work by means | |
634 | of this variable. | |
635 | ||
636 | @smallexample | |
637 | @group | |
638 | process-environment | |
639 | @result{} ("l=/usr/stanford/lib/gnuemacs/lisp" | |
640 | "PATH=.:/user/lewis/bin:/usr/class:/nfsusr/local/bin" | |
641 | "USER=lewis" | |
642 | @end group | |
643 | @group | |
644 | "TERM=ibmapa16" | |
645 | "SHELL=/bin/csh" | |
646 | "HOME=/user/lewis") | |
647 | @end group | |
648 | @end smallexample | |
649 | @end defvar | |
650 | ||
a890e1b0 RS |
651 | @defvar invocation-name |
652 | This variable holds the program name under which Emacs was invoked. The | |
653 | value is a string, and does not include a directory name. | |
654 | @end defvar | |
655 | ||
656 | @defvar invocation-directory | |
657 | This variable holds the directory from which the Emacs executable was | |
658 | invoked, or perhaps @code{nil} if that directory cannot be determined. | |
659 | @end defvar | |
660 | ||
661 | @defvar installation-directory | |
662 | If non-@code{nil}, this is a directory within which to look for the | |
663 | @file{lib-src} and @file{etc} subdirectories. This is non-@code{nil} | |
664 | when Emacs can't find those directories in their standard installed | |
665 | locations, but can find them near where the Emacs executable was found. | |
666 | @end defvar | |
667 | ||
73804d4b RS |
668 | @defun load-average |
669 | This function returns the current 1 minute, 5 minute and 15 minute | |
670 | load averages in a list. The values are integers that are 100 times | |
671 | the system load averages. (The load averages indicate the number of | |
672 | processes trying to run.) | |
673 | ||
674 | @example | |
675 | @group | |
676 | (load-average) | |
677 | @result{} (169 48 36) | |
678 | @end group | |
679 | ||
680 | @group | |
681 | lewis@@rocky[5] % uptime | |
682 | 11:55am up 1 day, 19:37, 3 users, | |
683 | load average: 1.69, 0.48, 0.36 | |
684 | @end group | |
685 | @end example | |
686 | @end defun | |
687 | ||
688 | @defun emacs-pid | |
689 | This function returns the process @sc{id} of the Emacs process. | |
690 | @end defun | |
691 | ||
692 | @defun setprv privilege-name &optional setp getprv | |
693 | This function sets or resets a VMS privilege. (It does not exist on | |
694 | Unix.) The first arg is the privilege name, as a string. The second | |
695 | argument, @var{setp}, is @code{t} or @code{nil}, indicating whether the | |
696 | privilege is to be turned on or off. Its default is @code{nil}. The | |
697 | function returns @code{t} if successful, @code{nil} otherwise. | |
698 | ||
699 | If the third argument, @var{getprv}, is non-@code{nil}, @code{setprv} | |
700 | does not change the privilege, but returns @code{t} or @code{nil} | |
701 | indicating whether the privilege is currently enabled. | |
702 | @end defun | |
703 | ||
704 | @node User Identification | |
705 | @section User Identification | |
706 | ||
707 | @defun user-login-name | |
708 | This function returns the name under which the user is logged in. If | |
709 | the environment variable @code{LOGNAME} is set, that value is used. | |
710 | Otherwise, if the environment variable @code{USER} is set, that value is | |
711 | used. Otherwise, the value is based on the effective @sc{uid}, not the | |
712 | real @sc{uid}. | |
713 | ||
714 | @example | |
715 | @group | |
716 | (user-login-name) | |
717 | @result{} "lewis" | |
718 | @end group | |
719 | @end example | |
720 | @end defun | |
721 | ||
722 | @defun user-real-login-name | |
723 | This function returns the user name corresponding to Emacs's real | |
724 | @sc{uid}. This ignores the effective @sc{uid} and ignores the | |
725 | environment variables @code{LOGNAME} and @code{USER}. | |
726 | @end defun | |
727 | ||
728 | @defun user-full-name | |
729 | This function returns the full name of the user. | |
730 | ||
731 | @example | |
732 | @group | |
733 | (user-full-name) | |
734 | @result{} "Bil Lewis" | |
735 | @end group | |
736 | @end example | |
737 | @end defun | |
738 | ||
739 | @defun user-real-uid | |
740 | This function returns the real @sc{uid} of the user. | |
741 | ||
742 | @example | |
743 | @group | |
744 | (user-real-uid) | |
745 | @result{} 19 | |
746 | @end group | |
747 | @end example | |
748 | @end defun | |
749 | ||
750 | @defun user-uid | |
751 | This function returns the effective @sc{uid} of the user. | |
752 | @end defun | |
753 | ||
754 | @node Time of Day | |
755 | @section Time of Day | |
756 | ||
757 | This section explains how to determine the current time and the time | |
758 | zone. | |
759 | ||
760 | @defun current-time-string &optional time-value | |
761 | This function returns the current time and date as a humanly-readable | |
762 | string. The format of the string is unvarying; the number of characters | |
763 | used for each part is always the same, so you can reliably use | |
764 | @code{substring} to extract pieces of it. However, it would be wise to | |
765 | count the characters from the beginning of the string rather than from | |
766 | the end, as additional information may be added at the end. | |
767 | ||
768 | @c Emacs 19 feature | |
769 | The argument @var{time-value}, if given, specifies a time to format | |
770 | instead of the current time. The argument should be a cons cell | |
771 | containing two integers, or a list whose first two elements are | |
772 | integers. Thus, you can use times obtained from @code{current-time} | |
773 | (see below) and from @code{file-attributes} (@pxref{File Attributes}). | |
774 | ||
775 | @example | |
776 | @group | |
777 | (current-time-string) | |
778 | @result{} "Wed Oct 14 22:21:05 1987" | |
779 | @end group | |
780 | @end example | |
781 | @end defun | |
782 | ||
783 | @c Emacs 19 feature | |
784 | @defun current-time | |
785 | This function returns the system's time value as a list of three | |
786 | integers: @code{(@var{high} @var{low} @var{microsec})}. The integers | |
787 | @var{high} and @var{low} combine to give the number of seconds since | |
788 | 0:00 January 1, 1970, which is | |
789 | @ifinfo | |
790 | @var{high} * 2**16 + @var{low}. | |
791 | @end ifinfo | |
792 | @tex | |
793 | $high*-2^{16}+low$. | |
794 | @end tex | |
795 | ||
796 | The third element, @var{microsec}, gives the microseconds since the | |
797 | start of the current second (or 0 for systems that return time only on | |
798 | the resolution of a second). | |
799 | ||
800 | The first two elements can be compared with file time values such as you | |
801 | get with the function @code{file-attributes}. @xref{File Attributes}. | |
802 | @end defun | |
803 | ||
804 | @c Emacs 19 feature | |
805 | @defun current-time-zone &optional time-value | |
806 | This function returns a list describing the time zone that the user is | |
807 | in. | |
808 | ||
809 | The value has the form @code{(@var{offset} @var{name})}. Here | |
810 | @var{offset} is an integer giving the number of seconds ahead of UTC | |
811 | (east of Greenwich). A negative value means west of Greenwich. The | |
812 | second element, @var{name} is a string giving the name of the time | |
813 | zone. Both elements change when daylight savings time begins or ends; | |
814 | if the user has specified a time zone that does not use a seasonal time | |
815 | adjustment, then the value is constant through time. | |
816 | ||
817 | If the operating system doesn't supply all the information necessary to | |
818 | compute the value, both elements of the list are @code{nil}. | |
819 | ||
820 | The argument @var{time-value}, if given, specifies a time to analyze | |
821 | instead of the current time. The argument should be a cons cell | |
822 | containing two integers, or a list whose first two elements are | |
823 | integers. Thus, you can use times obtained from @code{current-time} | |
824 | (see below) and from @code{file-attributes} (@pxref{File Attributes}). | |
825 | @end defun | |
826 | ||
827 | @node Timers | |
828 | @section Timers | |
829 | ||
830 | You can set up a timer to call a function at a specified future time. | |
831 | ||
832 | @defun run-at-time time repeat function &rest args | |
833 | This function arranges to call @var{function} with arguments @var{args} | |
834 | at time @var{time}. The argument @var{function} is a function to call | |
835 | later, and @var{args} are the arguments to give it when it is called. | |
836 | The time @var{time} is specified as a string. | |
837 | ||
838 | Absolute times may be specified in a wide variety of formats; The form | |
839 | @samp{@var{hour}:@var{min}:@var{sec} @var{timezone} | |
840 | @var{month}/@var{day}/@var{year}}, where all fields are numbers, works; | |
841 | the format that @code{current-time-string} returns is also allowed. | |
842 | ||
843 | To specify a relative time, use numbers followed by units. | |
844 | For example: | |
845 | ||
846 | @table @samp | |
847 | @item 1 min | |
848 | denotes 1 minute from now. | |
849 | @item 1 min 5 sec | |
850 | denotes 65 seconds from now. | |
851 | @item 1 min 2 sec 3 hour 4 day 5 week 6 fortnight 7 month 8 year | |
852 | denotes exactly 103 months, 123 days, and 10862 seconds from now. | |
853 | @end table | |
854 | ||
855 | If @var{time} is an integer, that specifies a relative time measured in | |
856 | seconds. | |
857 | ||
858 | The argument @var{repeat} specifies how often to repeat the call. If | |
859 | @var{repeat} is @code{nil}, there are no repetitions; @var{function} is | |
860 | called just once, at @var{time}. If @var{repeat} is an integer, it | |
861 | specifies a repetition period measured in seconds. | |
862 | @end defun | |
863 | ||
864 | @defun cancel-timer timer | |
865 | Cancel the requested action for @var{timer}, which should be a value | |
866 | previously returned by @code{run-at-time}. This cancels the effect of | |
867 | that call to @code{run-at-time}; the arrival of the specified time will | |
868 | not cause anything special to happen. | |
869 | @end defun | |
870 | ||
871 | @node Terminal Input | |
872 | @section Terminal Input | |
873 | @cindex terminal input | |
874 | ||
875 | This section describes functions and variables for recording or | |
876 | manipulating terminal input. See @ref{Display}, for related | |
877 | functions. | |
878 | ||
879 | @menu | |
880 | * Input Modes:: Options for how input is processed. | |
881 | * Translating Input:: Low level conversion of some characters or events | |
882 | into others. | |
883 | * Recording Input:: Saving histories of recent or all input events. | |
884 | @end menu | |
885 | ||
886 | @node Input Modes | |
887 | @subsection Input Modes | |
888 | @cindex input modes | |
889 | @cindex terminal input modes | |
890 | ||
891 | @defun set-input-mode interrupt flow meta quit-char | |
892 | This function sets the mode for reading keyboard input. If | |
893 | @var{interrupt} is non-null, then Emacs uses input interrupts. If it is | |
894 | @code{nil}, then it uses @sc{cbreak} mode. | |
895 | ||
896 | If @var{flow} is non-@code{nil}, then Emacs uses @sc{xon/xoff} (@kbd{C-q}, | |
897 | @kbd{C-s}) flow control for output to terminal. This has no effect except | |
898 | in @sc{cbreak} mode. @xref{Flow Control}. | |
899 | ||
900 | The default setting is system dependent. Some systems always use | |
901 | @sc{cbreak} mode regardless of what is specified. | |
902 | ||
903 | @c Emacs 19 feature | |
904 | The argument @var{meta} controls support for input character codes | |
905 | above 127. If @var{meta} is @code{t}, Emacs converts characters with | |
906 | the 8th bit set into Meta characters. If @var{meta} is @code{nil}, | |
907 | Emacs disregards the 8th bit; this is necessary when the terminal uses | |
908 | it as a parity bit. If @var{meta} is neither @code{t} nor @code{nil}, | |
909 | Emacs uses all 8 bits of input unchanged. This is good for terminals | |
910 | using European 8-bit character sets. | |
911 | ||
912 | @c Emacs 19 feature | |
913 | If @var{quit-char} is non-@code{nil}, it specifies the character to | |
914 | use for quitting. Normally this character is @kbd{C-g}. | |
915 | @xref{Quitting}. | |
916 | @end defun | |
917 | ||
918 | The @code{current-input-mode} function returns the input mode settings | |
919 | Emacs is currently using. | |
920 | ||
921 | @c Emacs 19 feature | |
922 | @defun current-input-mode | |
923 | This function returns current mode for reading keyboard input. It | |
924 | returns a list, corresponding to the arguments of @code{set-input-mode}, | |
925 | of the form @code{(@var{interrupt} @var{flow} @var{meta} @var{quit})} in | |
926 | which: | |
927 | @table @var | |
928 | @item interrupt | |
929 | is non-@code{nil} when Emacs is using interrupt-driven input. If | |
930 | @code{nil}, Emacs is using @sc{cbreak} mode. | |
931 | @item flow | |
932 | is non-@code{nil} if Emacs uses @sc{xon/xoff} (@kbd{C-q}, @kbd{C-s}) | |
933 | flow control for output to the terminal. This value has no effect | |
934 | unless @var{interrupt} is non-@code{nil}. | |
935 | @item meta | |
936 | is non-@code{t} if Emacs treats the eighth bit of input characters as | |
937 | the meta bit; @code{nil} means Emacs clears the eighth bit of every | |
938 | input character; any other value means Emacs uses all eight bits as the | |
939 | basic character code. | |
940 | @item quit | |
941 | is the character Emacs currently uses for quitting, usually @kbd{C-g}. | |
942 | @end table | |
943 | @end defun | |
944 | ||
945 | @defvar meta-flag | |
946 | This variable used to control whether to treat the eight bit in keyboard | |
947 | input characters as the @key{Meta} bit. @code{nil} meant no, and | |
948 | anything else meant yes. This variable existed in Emacs versions 18 and | |
949 | earlier but no longer exists in Emacs 19; use @code{set-input-mode} | |
950 | instead. | |
951 | @end defvar | |
952 | ||
953 | @node Translating Input | |
954 | @subsection Translating Input Events | |
955 | @cindex translating input events | |
956 | ||
957 | This section describes features for translating input events into other | |
958 | input events before they become part of key sequences. | |
959 | ||
960 | @c Emacs 19 feature | |
961 | @defvar extra-keyboard-modifiers | |
962 | This variable lets Lisp programs ``press'' the modifier keys on the | |
963 | keyboard. The value is a bit mask: | |
964 | ||
965 | @table @asis | |
966 | @item 1 | |
967 | The @key{SHIFT} key. | |
968 | @item 2 | |
969 | The @key{LOCK} key. | |
970 | @item 4 | |
971 | The @key{CTL} key. | |
972 | @item 8 | |
973 | The @key{META} key. | |
974 | @end table | |
975 | ||
976 | Each time the user types a keyboard key, it is altered as if the | |
977 | modifier keys specified in the bit mask were held down. | |
978 | ||
979 | When you use X windows, the program can ``press'' any of the modifier | |
980 | keys in this way. Otherwise, only the @key{CTL} and @key{META} keys can | |
981 | be virtually pressed. | |
982 | @end defvar | |
983 | ||
984 | @defvar keyboard-translate-table | |
985 | This variable is the translate table for keyboard characters. It lets | |
986 | you reshuffle the keys on the keyboard without changing any command | |
987 | bindings. Its value must be a string or @code{nil}. | |
988 | ||
989 | If @code{keyboard-translate-table} is a string, then each character read | |
990 | from the keyboard is looked up in this string and the character in the | |
991 | string is used instead. If the string is of length @var{n}, character codes | |
992 | @var{n} and up are untranslated. | |
993 | ||
994 | In the example below, we set @code{keyboard-translate-table} to a | |
995 | string of 128 characters. Then we fill it in to swap the characters | |
996 | @kbd{C-s} and @kbd{C-\} and the characters @kbd{C-q} and @kbd{C-^}. | |
997 | Subsequently, typing @kbd{C-\} has all the usual effects of typing | |
998 | @kbd{C-s}, and vice versa. (@xref{Flow Control} for more information on | |
999 | this subject.) | |
1000 | ||
1001 | @cindex flow control example | |
1002 | @example | |
1003 | @group | |
1004 | (defun evade-flow-control () | |
1005 | "Replace C-s with C-\ and C-q with C-^." | |
1006 | (interactive) | |
1007 | @end group | |
1008 | @group | |
1009 | (let ((the-table (make-string 128 0))) | |
1010 | (let ((i 0)) | |
1011 | (while (< i 128) | |
1012 | (aset the-table i i) | |
1013 | (setq i (1+ i)))) | |
1014 | @end group | |
1015 | ;; @r{Swap @kbd{C-s} and @kbd{C-\}.} | |
1016 | (aset the-table ?\034 ?\^s) | |
1017 | (aset the-table ?\^s ?\034) | |
1018 | @group | |
1019 | ;; @r{Swap @kbd{C-q} and @kbd{C-^}.} | |
1020 | (aset the-table ?\036 ?\^q) | |
1021 | (aset the-table ?\^q ?\036) | |
1022 | (setq keyboard-translate-table the-table))) | |
1023 | @end group | |
1024 | @end example | |
1025 | ||
1026 | Note that this translation is the first thing that happens to a | |
1027 | character after it is read from the terminal. Record-keeping features | |
1028 | such as @code{recent-keys} and dribble files record the characters after | |
1029 | translation. | |
1030 | @end defvar | |
1031 | ||
1032 | @defun keyboard-translate from to | |
1033 | This function modifies @code{keyboard-translate-table} to translate | |
1034 | character code @var{from} into character code @var{to}. It creates | |
1035 | or enlarges the translate table if necessary. | |
1036 | @end defun | |
1037 | ||
1038 | @defvar function-key-map | |
1039 | This variable holds a keymap which describes the character sequences | |
1040 | sent by function keys on an ordinary character terminal. This keymap | |
1041 | uses the data structure as other keymaps, but is used differently: it | |
1042 | specifies translations to make while reading events. | |
1043 | ||
1044 | If @code{function-key-map} ``binds'' a key sequence @var{k} to a vector | |
1045 | @var{v}, then when @var{k} appears as a subsequence @emph{anywhere} in a | |
1046 | key sequence, it is replaced with the events in @var{v}. | |
1047 | ||
1048 | For example, VT100 terminals send @kbd{@key{ESC} O P} when the | |
1049 | keypad PF1 key is pressed. Therefore, we want Emacs to translate | |
1050 | that sequence of events into the single event @code{pf1}. We accomplish | |
1051 | this by ``binding'' @kbd{@key{ESC} O P} to @code{[pf1]} in | |
1052 | @code{function-key-map}, when using a VT100. | |
1053 | ||
1054 | Thus, typing @kbd{C-c @key{PF1}} sends the character sequence @kbd{C-c | |
1055 | @key{ESC} O P}; later the function @code{read-key-sequence} translates | |
1056 | this back into @kbd{C-c @key{PF1}}, which it returns as the vector | |
1057 | @code{[?\C-c pf1]}. | |
1058 | ||
1059 | Entries in @code{function-key-map} are ignored if they conflict with | |
1060 | bindings made in the minor mode, local, or global keymaps. The intent | |
1061 | is that the character sequences that function keys send should not have | |
1062 | command bindings in their own right. | |
1063 | ||
1064 | The value of @code{function-key-map} is usually set up automatically | |
1065 | according to the terminal's Terminfo or Termcap entry, but sometimes | |
1066 | those need help from terminal-specific Lisp files. Emacs comes with | |
1067 | terminal-specific files for many common terminals; their main purpose is | |
1068 | to make entries in @code{function-key-map} beyond those that can be | |
1069 | deduced from Termcap and Terminfo. @xref{Terminal-Specific}. | |
1070 | ||
1071 | Emacs versions 18 and earlier used totally different means of detecting | |
1072 | the character sequences that represent function keys. | |
1073 | @end defvar | |
1074 | ||
1075 | @defvar key-translation-map | |
1076 | This variable is another keymap used just like @code{function-key-map} | |
1077 | to translate input events into other events. It differs from | |
1078 | @code{function-key-map} in two ways: | |
1079 | ||
1080 | @itemize @bullet | |
1081 | @item | |
1082 | @code{key-translation-map} goes to work after @code{function-key-map} is | |
1083 | finished; it receives the results of translation by | |
1084 | @code{function-key-map}. | |
1085 | ||
1086 | @item | |
1087 | @code{key-translation-map} overrides actual key bindings. | |
1088 | @end itemize | |
1089 | ||
1090 | The intent of @code{key-translation-map} is for users to map one | |
1091 | character set to another, including ordinary characters normally bound | |
1092 | to @code{self-insert-command}. | |
1093 | @end defvar | |
1094 | ||
1095 | @cindex key translation function | |
1096 | You can use @code{function-key-map} or @code{key-translation-map} for | |
1097 | more than simple aliases, by using a function, instead of a key | |
1098 | sequence, as the ``translation'' of a key. Then this function is called | |
1099 | to compute the translation of that key. | |
1100 | ||
1101 | The key translation function receives one argument, which is the prompt | |
1102 | that was specified in @code{read-key-sequence}---or @code{nil} if the | |
1103 | key sequence is being read by the editor command loop. In most cases | |
1104 | you can ignore the prompt value. | |
1105 | ||
1106 | If the function reads input itself, it can have the effect of altering | |
1107 | the event that follows. For example, here's how to define @kbd{C-c h} | |
1108 | to turn the character that follows into a Hyper character: | |
1109 | ||
1110 | @example | |
1111 | (defun hyperify (prompt) | |
1112 | (let ((e (read-event))) | |
1113 | (vector (if (numberp e) | |
1114 | (logior (lsh 1 20) e) | |
1115 | (if (memq 'hyper (event-modifiers e)) | |
1116 | e | |
1117 | (add-event-modifier "H-" e)))))) | |
1118 | ||
1119 | (defun add-event-modifier (string e) | |
1120 | (let ((symbol (if (symbolp e) e (car e)))) | |
1121 | (setq symbol (intern (concat string | |
1122 | (symbol-name symbol)))) | |
1123 | (if (symbolp e) | |
1124 | symbol | |
1125 | (cons symbol (cdr e))))) | |
1126 | ||
1127 | (define-key function-key-map "\C-ch" 'hyperify) | |
1128 | @end example | |
1129 | ||
1130 | @pindex iso-transl | |
1131 | @cindex Latin-1 character set (input) | |
1132 | @cindex ISO Latin-1 characters (input) | |
1133 | The @file{iso-transl} library uses this feature to provide a way of | |
1134 | inputting non-ASCII Latin-1 characters. | |
1135 | ||
1136 | @node Recording Input | |
1137 | @subsection Recording Input | |
1138 | ||
1139 | @defun recent-keys | |
1140 | This function returns a vector containing the last 100 input events | |
1141 | from the keyboard or mouse. All input events are included, whether or | |
1142 | not they were used as parts of key sequences. Thus, you always get the | |
1143 | last 100 inputs, not counting keyboard macros. (Events from keyboard | |
1144 | macros are excluded because they are less interesting for debugging; it | |
1145 | should be enough to see the events which invoked the macros.) | |
1146 | @end defun | |
1147 | ||
1148 | @deffn Command open-dribble-file filename | |
1149 | @cindex dribble file | |
1150 | This function opens a @dfn{dribble file} named @var{filename}. When a | |
1151 | dribble file is open, each input event from the keyboard or mouse (but | |
1152 | not those from keyboard macros) is written in that file. A | |
1153 | non-character event is expressed using its printed representation | |
1154 | surrounded by @samp{<@dots{}>}. | |
1155 | ||
1156 | You close the dribble file by calling this function with an argument | |
1157 | of @code{nil}. | |
1158 | ||
1159 | This function is normally used to record the input necessary to | |
1160 | trigger an Emacs bug, for the sake of a bug report. | |
1161 | ||
1162 | @example | |
1163 | @group | |
1164 | (open-dribble-file "~/dribble") | |
1165 | @result{} nil | |
1166 | @end group | |
1167 | @end example | |
1168 | @end deffn | |
1169 | ||
1170 | See also the @code{open-termscript} function (@pxref{Terminal Output}). | |
1171 | ||
1172 | @node Terminal Output | |
1173 | @section Terminal Output | |
1174 | @cindex terminal output | |
1175 | ||
1176 | The terminal output functions send output to the terminal or keep | |
1177 | track of output sent to the terminal. The variable @code{baud-rate} | |
1178 | tells you what Emacs thinks is the output speed of the terminal. | |
1179 | ||
1180 | @defvar baud-rate | |
1181 | This variable's value is the output speed of the terminal, as far as | |
1182 | Emacs knows. Setting this variable does not change the speed of actual | |
1183 | data transmission, but the value is used for calculations such as | |
1184 | padding. It also affects decisions about whether to scroll part of the | |
1185 | screen or repaint---even when using a window system, (We designed it | |
1186 | this way despite the fact that a window system has no true ``output | |
1187 | speed'', to give you a way to tune these decisions.) | |
1188 | ||
1189 | The value is measured in baud. | |
1190 | @end defvar | |
1191 | ||
1192 | If you are running across a network, and different parts of the | |
1193 | network work at different baud rates, the value returned by Emacs may be | |
1194 | different from the value used by your local terminal. Some network | |
1195 | protocols communicate the local terminal speed to the remote machine, so | |
1196 | that Emacs and other programs can get the proper value, but others do | |
1197 | not. If Emacs has the wrong value, it makes decisions that are less | |
1198 | than optimal. To fix the problem, set @code{baud-rate}. | |
1199 | ||
1200 | @defun baud-rate | |
1201 | This function returns the value of the variable @code{baud-rate}. In | |
1202 | Emacs versions 18 and earlier, this was the only way to find out the | |
1203 | terminal speed. | |
1204 | @end defun | |
1205 | ||
1206 | @defun send-string-to-terminal string | |
1207 | This function sends @var{string} to the terminal without alteration. | |
1208 | Control characters in @var{string} have terminal-dependent effects. | |
1209 | ||
1210 | One use of this function is to define function keys on terminals that | |
1211 | have downloadable function key definitions. For example, this is how on | |
1212 | certain terminals to define function key 4 to move forward four | |
1213 | characters (by transmitting the characters @kbd{C-u C-f} to the | |
1214 | computer): | |
1215 | ||
1216 | @example | |
1217 | @group | |
1218 | (send-string-to-terminal "\eF4\^U\^F") | |
1219 | @result{} nil | |
1220 | @end group | |
1221 | @end example | |
1222 | @end defun | |
1223 | ||
1224 | @deffn Command open-termscript filename | |
1225 | @cindex termscript file | |
1226 | This function is used to open a @dfn{termscript file} that will record | |
1227 | all the characters sent by Emacs to the terminal. It returns | |
1228 | @code{nil}. Termscript files are useful for investigating problems | |
1229 | where Emacs garbles the screen, problems that are due to incorrect | |
1230 | Termcap entries or to undesirable settings of terminal options more | |
1231 | often than to actual Emacs bugs. Once you are certain which characters | |
1232 | were actually output, you can determine reliably whether they correspond | |
1233 | to the Termcap specifications in use. | |
1234 | ||
1235 | See also @code{open-dribble-file} in @ref{Terminal Input}. | |
1236 | ||
1237 | @example | |
1238 | @group | |
1239 | (open-termscript "../junk/termscript") | |
1240 | @result{} nil | |
1241 | @end group | |
1242 | @end example | |
1243 | @end deffn | |
1244 | ||
1245 | @node Special Keysyms | |
1246 | @section System-Specific X11 Keysyms | |
1247 | ||
1248 | To define system-specific X11 keysyms, set the variable | |
1249 | @code{system-key-alist}. | |
1250 | ||
1251 | @defvar system-key-alist | |
1252 | This variable's value should be an alist with one element for each | |
1253 | system-specific keysym. An element has this form: @code{(@var{code} | |
1254 | . @var{symbol})}, where @var{code} is the numeric keysym code (not | |
1255 | including the ``vendor specific'' bit, 1 << 28), and @var{symbol} is the | |
1256 | name for the function key. | |
1257 | ||
1258 | For example @code{(168 . mute-acute)} defines a system-specific key used | |
1259 | by HP X servers whose numeric code is (1 << 28) + 168. | |
1260 | ||
1261 | It is not a problem if the alist defines keysyms for other X servers, as | |
1262 | long as they don't conflict with the ones used by the X server actually | |
1263 | in use. | |
1264 | @end defvar | |
1265 | ||
1266 | @node Flow Control | |
1267 | @section Flow Control | |
1268 | @cindex flow control characters | |
1269 | ||
1270 | This section attempts to answer the question ``Why does Emacs choose | |
1271 | to use flow-control characters in its command character set?'' For a | |
1272 | second view on this issue, read the comments on flow control in the | |
1273 | @file{emacs/INSTALL} file from the distribution; for help with Termcap | |
1274 | entries and DEC terminal concentrators, see @file{emacs/etc/TERMS}. | |
1275 | ||
1276 | @cindex @kbd{C-s} | |
1277 | @cindex @kbd{C-q} | |
1278 | At one time, most terminals did not need flow control, and none used | |
1279 | @code{C-s} and @kbd{C-q} for flow control. Therefore, the choice of | |
1280 | @kbd{C-s} and @kbd{C-q} as command characters was uncontroversial. | |
1281 | Emacs, for economy of keystrokes and portability, used nearly all the | |
1282 | @sc{ASCII} control characters, with mnemonic meanings when possible; | |
1283 | thus, @kbd{C-s} for search and @kbd{C-q} for quote. | |
1284 | ||
1285 | Later, some terminals were introduced which required these characters | |
1286 | for flow control. They were not very good terminals for full-screen | |
1287 | editing, so Emacs maintainers did not pay attention. In later years, | |
1288 | flow control with @kbd{C-s} and @kbd{C-q} became widespread among | |
1289 | terminals, but by this time it was usually an option. And the majority | |
1290 | of users, who can turn flow control off, were unwilling to switch to | |
1291 | less mnemonic key bindings for the sake of flow control. | |
1292 | ||
1293 | So which usage is ``right'', Emacs's or that of some terminal and | |
1294 | concentrator manufacturers? This question has no simple answer. | |
1295 | ||
1296 | One reason why we are reluctant to cater to the problems caused by | |
1297 | @kbd{C-s} and @kbd{C-q} is that they are gratuitous. There are other | |
1298 | techniques (albeit less common in practice) for flow control that | |
1299 | preserve transparency of the character stream. Note also that their use | |
1300 | for flow control is not an official standard. Interestingly, on the | |
1301 | model 33 teletype with a paper tape punch (which is very old), @kbd{C-s} | |
1302 | and @kbd{C-q} were sent by the computer to turn the punch on and off! | |
1303 | ||
1304 | GNU Emacs version 19 provides a convenient way of enabling flow | |
1305 | control if you want it: call the function @code{enable-flow-control}. | |
1306 | ||
1307 | @defun enable-flow-control | |
1308 | This function enables use of @kbd{C-s} and @kbd{C-q} for output flow | |
1309 | control, and provides the characters @kbd{C-\} and @kbd{C-^} as aliases | |
1310 | for them using @code{keyboard-translate-table} (@pxref{Translating Input}). | |
1311 | @end defun | |
1312 | ||
1313 | You can use the function @code{enable-flow-control-on} in your | |
1314 | @file{.emacs} file to enable flow control automatically on certain | |
1315 | terminal types. | |
1316 | ||
1317 | @defun enable-flow-control-on &rest termtypes | |
1318 | This function enables flow control, and the aliases @kbd{C-\} and @kbd{C-^}, | |
1319 | if the terminal type is one of @var{termtypes}. For example: | |
1320 | ||
1321 | @smallexample | |
1322 | (enable-flow-control-on "vt200" "vt300" "vt101" "vt131") | |
1323 | @end smallexample | |
1324 | @end defun | |
1325 | ||
1326 | Here is how @code{enable-flow-control} does its job: | |
1327 | ||
1328 | @enumerate | |
1329 | @item | |
1330 | @cindex @sc{cbreak} | |
1331 | It sets @sc{cbreak} mode for terminal input, and tells the operating | |
1332 | system to handle flow control, with @code{(set-input-mode nil t)}. | |
1333 | ||
1334 | @item | |
1335 | It sets up @code{keyboard-translate-table} to translate @kbd{C-\} and | |
1336 | @kbd{C-^} into @kbd{C-s} and @kbd{C-q} were typed. Except at its very | |
1337 | lowest level, Emacs never knows that the characters typed were anything | |
1338 | but @kbd{C-s} and @kbd{C-q}, so you can in effect type them as @kbd{C-\} | |
1339 | and @kbd{C-^} even when they are input for other commands. | |
1340 | @xref{Translating Input}. | |
a890e1b0 | 1341 | @end enumerate |
73804d4b RS |
1342 | |
1343 | If the terminal is the source of the flow control characters, then once | |
1344 | you enable kernel flow control handling, you probably can make do with | |
1345 | less padding than normal for that terminal. You can reduce the amount | |
1346 | of padding by customizing the Termcap entry. You can also reduce it by | |
1347 | setting @code{baud-rate} to a smaller value so that Emacs uses a smaller | |
1348 | speed when calculating the padding needed. @xref{Terminal Output}. | |
1349 | ||
1350 | @node Batch Mode | |
1351 | @section Batch Mode | |
1352 | @cindex batch mode | |
1353 | @cindex noninteractive use | |
1354 | ||
1355 | The command line option @samp{-batch} causes Emacs to run | |
1356 | noninteractively. In this mode, Emacs does not read commands from the | |
1357 | terminal, it does not alter the terminal modes, and it does not expect | |
1358 | to be outputting to an erasable screen. The idea is that you specify | |
1359 | Lisp programs to run; when they are finished, Emacs should exit. The | |
1360 | way to specify the programs to run is with @samp{-l @var{file}}, which | |
1361 | loads the library named @var{file}, and @samp{-f @var{function}}, which | |
1362 | calls @var{function} with no arguments. | |
1363 | ||
1364 | Any Lisp program output that would normally go to the echo area, | |
1365 | either using @code{message} or using @code{prin1}, etc., with @code{t} | |
1366 | as the stream, goes instead to Emacs's standard output descriptor when | |
1367 | in batch mode. Thus, Emacs behaves much like a noninteractive | |
1368 | application program. (The echo area output that Emacs itself normally | |
1369 | generates, such as command echoing, is suppressed entirely.) | |
1370 | ||
1371 | @defvar noninteractive | |
1372 | This variable is non-@code{nil} when Emacs is running in batch mode. | |
1373 | @end defvar |