1 @c This is part of the Emacs manual.
2 @c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 2000, 2001,
3 @c 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
4 @c See file emacs.texi for copying conditions.
5 @node Customization, Quitting, Amusements, Top
9 This chapter talks about various topics relevant to adapting the
10 behavior of Emacs in minor ways.
12 See @cite{The Emacs Lisp Reference Manual}
15 @xref{Top, Emacs Lisp, Emacs Lisp, elisp, The Emacs Lisp
18 for how to make more far-reaching changes. @xref{X Resources},
19 for information on using X resources to customize Emacs.
21 Customization that you do within Emacs normally affects only the
22 particular Emacs session that you do it in---it does not persist
23 between sessions unless you save the customization in a file such as
24 @file{.emacs} or @file{.Xdefaults} that will affect future sessions.
25 @xref{Init File}. In the customization buffer, when you save
26 customizations for future sessions, this actually works by editing
27 @file{.emacs} for you.
29 Another means of customization is the keyboard macro, which is a
30 sequence of keystrokes to be replayed with a single command.
31 @xref{Keyboard Macros}, for full instruction how to record, manage, and
32 replay sequences of keys.
35 * Minor Modes:: Each minor mode is one feature you can turn on
36 independently of any others.
37 * Easy Customization:: Convenient way to browse and change settings.
38 * Variables:: Many Emacs commands examine Emacs variables
39 to decide what to do; by setting variables,
40 you can control their functioning.
41 * Key Bindings:: The keymaps say what command each key runs.
42 By changing them, you can "redefine keys".
43 * Syntax:: The syntax table controls how words and
44 expressions are parsed.
45 * Init File:: How to write common customizations in the
54 Minor modes are optional features which you can turn on or off. For
55 example, Auto Fill mode is a minor mode in which @key{SPC} breaks lines
56 between words as you type. All the minor modes are independent of each
57 other and of the selected major mode. Most minor modes say in the mode
58 line when they are on; for example, @samp{Fill} in the mode line means
59 that Auto Fill mode is on.
61 Append @code{-mode} to the name of a minor mode to get the name of a
62 command that turns the mode on or off. Thus, the command to
63 enable or disable Auto Fill mode is called @code{auto-fill-mode}. These
64 commands are usually invoked with @kbd{M-x}, but you can bind keys to them
65 if you wish. With no argument, the function turns the mode on if it was
66 off and off if it was on. This is known as @dfn{toggling}. A positive
67 argument always turns the mode on, and an explicit zero argument or a
68 negative argument always turns it off.
70 Some minor modes are global: while enabled, they affect everything
71 you do in the Emacs session, in all buffers. Other minor modes are
72 buffer-local; they apply only to the current buffer, so you can enable
73 the mode in certain buffers and not others.
75 For most minor modes, the command name is also the name of a
76 variable. The variable's value is non-@code{nil} if the mode is
77 enabled and @code{nil} if it is disabled. Some minor-mode commands
78 work by just setting the variable. For example, the command
79 @code{abbrev-mode} works by setting the value of @code{abbrev-mode} as
80 a variable; it is this variable that directly turns Abbrev mode on and
81 off. You can directly set the variable's value instead of calling the
82 mode function. For other minor modes, you need to either set the
83 variable through the Customize interface or call the mode function to
84 correctly enable or disable the mode. To check which of these two
85 possibilities applies to a given minor mode, use @kbd{C-h v} to ask
86 for documentation on the variable name.
88 For minor mode commands that work by just setting the minor mode
89 variable, that variable provides a good way for Lisp programs to turn
90 minor modes on and off; it is also useful in a file's local variables
91 list (@pxref{File Variables}). But please think twice before setting
92 minor modes with a local variables list, because most minor modes are
93 a matter of user preference---other users editing the same file might
94 not want the same minor modes you prefer.
96 The most useful buffer-local minor modes include Abbrev mode, Auto
97 Fill mode, Auto Save mode, Font-Lock mode, Glasses mode, ISO Accents
98 mode, Outline minor mode, Overwrite mode, and Binary Overwrite mode.
100 Abbrev mode allows you to define abbreviations that automatically expand
101 as you type them. For example, @samp{amd} might expand to @samp{abbrev
102 mode}. @xref{Abbrevs}, for full information.
104 Auto Fill mode allows you to enter filled text without breaking lines
105 explicitly. Emacs inserts newlines as necessary to prevent lines from
106 becoming too long. @xref{Filling}.
108 Auto Save mode causes the contents of a buffer to be saved
109 periodically to reduce the amount of work you can lose in case of a
110 system crash. @xref{Auto Save}.
112 Enriched mode enables editing and saving of formatted text.
113 @xref{Formatted Text}.
115 Flyspell mode automatically highlights misspelled words.
118 Font-Lock mode automatically highlights certain textual units found in
119 programs, such as comments, strings, and function names being defined.
120 This requires a window system that can display multiple fonts.
123 ISO Accents mode makes the characters @samp{`}, @samp{'}, @samp{"},
124 @samp{^}, @samp{/} and @samp{~} combine with the following letter, to
125 produce an accented letter in the ISO Latin-1 character set. The
126 newer and more general feature of input methods more or less
127 supersedes ISO Accents mode. @xref{Single-Byte Character Support}.
129 Outline minor mode provides the same facilities as the major mode
130 called Outline mode; but since it is a minor mode instead, you can
131 combine it with any major mode. @xref{Outline Mode}.
133 @cindex Overwrite mode
134 @cindex mode, Overwrite
135 Overwrite mode causes ordinary printing characters to replace existing
136 text instead of shoving it to the right. For example, if point is in
137 front of the @samp{B} in @samp{FOOBAR}, then in Overwrite mode typing a
138 @kbd{G} changes it to @samp{FOOGAR}, instead of producing @samp{FOOGBAR}
139 as usual. In Overwrite mode, the command @kbd{C-q} inserts the next
140 character whatever it may be, even if it is a digit---this gives you a
141 way to insert a character instead of replacing an existing character.
143 @findex overwrite-mode
145 The command @code{overwrite-mode} is an exception to the rule that
146 commands which toggle minor modes are normally not bound to keys: it is
147 bound to the @key{INSERT} function key. This is because many other
148 programs bind @key{INSERT} to similar functions.
150 @findex binary-overwrite-mode
151 Binary Overwrite mode is a variant of Overwrite mode for editing
152 binary files; it treats newlines and tabs like other characters, so that
153 they overwrite other characters and can be overwritten by them.
154 In Binary Overwrite mode, digits after @kbd{C-q} specify an
155 octal character code, as usual.
157 Here are some useful minor modes that normally apply to all buffers
158 at once. Since Line Number mode and Transient Mark mode can be
159 enabled or disabled just by setting the value of the minor mode
160 variable, you @emph{can} set them differently for particular buffers,
161 by explicitly making the corresponding variable local in those
162 buffers. @xref{Locals}.
164 Icomplete mode displays an indication of available completions when
165 you are in the minibuffer and completion is active. @xref{Completion
168 Line Number mode enables continuous display in the mode line of the
169 line number of point, and Column Number mode enables display of the
170 column number. @xref{Mode Line}.
172 Scroll Bar mode gives each window a scroll bar (@pxref{Scroll Bars}).
173 Menu Bar mode gives each frame a menu bar (@pxref{Menu Bars}). Both of
174 these modes are enabled by default when you use the X Window System.
176 In Transient Mark mode, every change in the buffer contents
177 ``deactivates'' the mark, so that commands that operate on the region
178 will get an error. This means you must either set the mark, or
179 explicitly ``reactivate'' it, before each command that uses the region.
180 The advantage of Transient Mark mode is that Emacs can display the
181 region highlighted. @xref{Mark}.
183 @node Easy Customization
184 @section Easy Customization Interface
187 Emacs has many @dfn{settings} which have values that you can specify
188 in order to customize various commands. Many are documented in this
189 manual. Most settings are @dfn{user options}---that is to say, Lisp
190 variables (@pxref{Variables})---so their names appear in the Variable
191 Index (@pxref{Variable Index}). The other settings are faces and
192 their attributes (@pxref{Faces}).
195 @cindex customization buffer
196 You can browse interactively through settings and change them using
197 @kbd{M-x customize}. This command creates a @dfn{customization
198 buffer}, which offers commands to navigate through a logically
199 organized structure of the Emacs settings; you can also use it to edit
200 and set their values, and to save settings permanently in your
201 @file{~/.emacs} file (@pxref{Init File}).
203 The appearance of the example buffers in this section is typically
204 different under a window system, since faces are then used to indicate
205 buttons and editable fields.
208 * Groups: Customization Groups. How settings are classified in a structure.
209 * Browsing: Browsing Custom. Browsing and searching for settings.
210 * Changing a Variable:: How to edit an option's value and set the option.
211 * Saving Customizations:: Specifying the file for saving customizations.
212 * Face Customization:: How to edit the attributes of a face.
213 * Specific Customization:: Making a customization buffer for specific
214 variables, faces, or groups.
215 * Custom Themes:: How to define collections of customized options
216 that can be loaded and unloaded together.
219 @node Customization Groups
220 @subsection Customization Groups
221 @cindex customization groups
223 For customization purposes, settings are organized into @dfn{groups}
224 to help you find them. Groups are collected into bigger groups, all
225 the way up to a master group called @code{Emacs}.
227 @kbd{M-x customize} creates a customization buffer that shows the
228 top-level @code{Emacs} group and the second-level groups immediately
229 under it. It looks like this, in part:
232 /- Emacs group: ---------------------------------------------------\
233 [State]: visible group members are all at standard values.
234 Customization of the One True Editor.
237 Editing group: [Go to Group]
238 Basic text editing facilities.
240 External group: [Go to Group]
241 Interfacing to external utilities.
243 @var{more second-level groups}
245 \- Emacs group end ------------------------------------------------/
250 This says that the buffer displays the contents of the @code{Emacs}
251 group. The other groups are listed because they are its contents. But
252 they are listed differently, without indentation and dashes, because
253 @emph{their} contents are not included. Each group has a single-line
254 documentation string; the @code{Emacs} group also has a @samp{[State]}
257 @cindex editable fields (customization buffer)
258 @cindex buttons (customization buffer)
259 Most of the text in the customization buffer is read-only, but it
260 typically includes some @dfn{editable fields} that you can edit.
261 There are also @dfn{buttons}, which do something when you @dfn{invoke}
262 them. To invoke a button, either click on it with @kbd{Mouse-1}, or
263 move point to it and type @key{RET}.
265 For example, the phrase @samp{[Go to Group]} that appears in a
266 second-level group is a button. Invoking it creates a new
267 customization buffer, which shows that group and its contents. This
268 is a kind of hypertext link to another group.
270 The @code{Emacs} group includes a few settings, but mainly it
271 contains other groups, which contain more groups, which contain the
272 settings. By browsing the hierarchy of groups, you will eventually
273 find the feature you are interested in customizing. Then you can use
274 the customization buffer to set that feature's settings. You can also
275 go straight to a particular group by name, using the command @kbd{M-x
278 @node Browsing Custom
279 @subsection Browsing and Searching for Options and Faces
280 @findex customize-browse
282 @kbd{M-x customize-browse} is another way to browse the available
283 settings. This command creates a special customization buffer which
284 shows only the names of groups and settings, and puts them in a
287 In this buffer, you can show the contents of a group by invoking
288 @samp{[+]}. When the group contents are visible, this button changes to
289 @samp{[-]}; invoking that hides the group contents.
291 Each setting in this buffer has a button which says @samp{[Group]},
292 @samp{[Option]} or @samp{[Face]}. Invoking this button creates an
293 ordinary customization buffer showing just that group and its
294 contents, just that user option, or just that face. This is the way
295 to change settings that you find with @kbd{M-x customize-browse}.
297 If you can guess part of the name of the settings you are interested
298 in, @kbd{M-x customize-apropos} is another way to search for settings.
299 However, unlike @code{customize} and @code{customize-browse},
300 @code{customize-apropos} can only find groups and settings that are
301 loaded in the current Emacs session. @xref{Specific Customization,,
302 Customizing Specific Items}.
304 @node Changing a Variable
305 @subsection Changing a Variable
307 Here is an example of what a variable (a user option) looks like in
308 the customization buffer:
311 Kill Ring Max: [Hide Value] 60
313 Maximum length of kill ring before oldest elements are thrown away.
316 The text following @samp{[Hide Value]}, @samp{60} in this case, indicates
317 the current value of the variable. If you see @samp{[Show Value]} instead of
318 @samp{[Hide Value]}, it means that the value is hidden; the customization
319 buffer initially hides values that take up several lines. Invoke
320 @samp{[Show Value]} to show the value.
322 The line after the variable name indicates the @dfn{customization
323 state} of the variable: in the example above, it says you have not
324 changed the option yet. The @samp{[State]} button at the beginning of
325 this line gives you a menu of various operations for customizing the
328 The line after the @samp{[State]} line displays the beginning of the
329 variable's documentation string. If there are more lines of
330 documentation, this line ends with a @samp{[More]} button; invoke that
331 to show the full documentation string.
333 To enter a new value for @samp{Kill Ring Max}, move point to the
334 value and edit it textually. For example, you can type @kbd{M-d},
335 then insert another number. As you begin to alter the text, you will
336 see the @samp{[State]} line change to say that you have edited the
340 [State]: EDITED, shown value does not take effect until you set or @r{@dots{}}
344 @cindex settings, how to set
345 Editing the value does not actually set the variable. To do that,
346 you must @dfn{set} the variable. To do this, invoke the
347 @samp{[State]} button and choose @samp{Set for Current Session}.
349 The state of the variable changes visibly when you set it:
352 [State]: SET for current session only.
355 You don't have to worry about specifying a value that is not valid;
356 the @samp{Set for Current Session} operation checks for validity and
357 will not install an unacceptable value.
359 @kindex M-TAB @r{(customization buffer)}
360 @findex widget-complete
361 While editing a field that is a file name, directory name,
362 command name, or anything else for which completion is defined, you
363 can type @kbd{M-@key{TAB}} (@code{widget-complete}) to do completion.
364 (@kbd{@key{ESC} @key{TAB}} and @kbd{C-M-i} do the same thing.)
366 Some variables have a small fixed set of possible legitimate values.
367 These variables don't let you edit the value textually. Instead, a
368 @samp{[Value Menu]} button appears before the value; invoke this
369 button to change the value. For a boolean ``on or off'' value, the
370 button says @samp{[Toggle]}, and it changes to the other value.
371 @samp{[Value Menu]} and @samp{[Toggle]} simply edit the buffer; the
372 changes take real effect when you use the @samp{Set for Current
375 Some variables have values with complex structure. For example, the
376 value of @code{file-coding-system-alist} is an association list. Here
377 is how it appears in the customization buffer:
380 File Coding System Alist: [Hide Value]
381 [INS] [DEL] File regexp: \.elc\'
382 Choice: [Value Menu] Encoding/decoding pair:
385 [INS] [DEL] File regexp: \(\`\|/\)loaddefs.el\'
386 Choice: [Value Menu] Encoding/decoding pair:
388 Encoding: raw-text-unix
389 [INS] [DEL] File regexp: \.tar\'
390 Choice: [Value Menu] Encoding/decoding pair:
391 Decoding: no-conversion
392 Encoding: no-conversion
393 [INS] [DEL] File regexp:
394 Choice: [Value Menu] Encoding/decoding pair:
399 Alist to decide a coding system to use for a file I/O @r{@dots{}}
400 operation. [Hide Rest]
401 The format is ((PATTERN . VAL) ...),
402 where PATTERN is a regular expression matching a file name,
403 @r{[@dots{}more lines of documentation@dots{}]}
407 Each association in the list appears on four lines, with several
408 editable fields and/or buttons. You can edit the regexps and coding
409 systems using ordinary editing commands. You can also invoke
410 @samp{[Value Menu]} to switch to a different kind of value---for
411 instance, to specify a function instead of a pair of coding systems.
413 To delete an association from the list, invoke the @samp{[DEL]} button
414 for that item. To add an association, invoke @samp{[INS]} at the
415 position where you want to add it. There is an @samp{[INS]} button
416 between each pair of association, another at the beginning and another
417 at the end, so you can add the new association at any position in the
420 @kindex TAB @r{(customization buffer)}
421 @kindex S-TAB @r{(customization buffer)}
422 @findex widget-forward
423 @findex widget-backward
424 Two special commands, @key{TAB} and @kbd{S-@key{TAB}}, are useful
425 for moving through the customization buffer. @key{TAB}
426 (@code{widget-forward}) moves forward to the next button or editable
427 field; @kbd{S-@key{TAB}} (@code{widget-backward}) moves backward to
428 the previous button or editable field.
430 Typing @key{RET} on an editable field also moves forward, just like
431 @key{TAB}. We set it up this way because people often type @key{RET}
432 when they are finished editing a field. To insert a newline within an
433 editable field, use @kbd{C-o} or @kbd{C-q C-j}.
435 @cindex saving a setting
436 @cindex settings, how to save
437 Setting the variable changes its value in the current Emacs session;
438 @dfn{saving} the value changes it for future sessions as well. To
439 save the variable, invoke @samp{[State]} and select the @samp{Save for
440 Future Sessions} operation. This works by writing code so as to set
441 the variable again, each time you start Emacs (@pxref{Saving
444 You can also restore the variable to its standard value by invoking
445 @samp{[State]} and selecting the @samp{Erase Customization} operation.
446 There are actually four reset operations:
450 If you have made some modifications and not yet set the variable,
451 this restores the text in the customization buffer to match
455 This restores the value of the variable to the last saved value,
456 and updates the text accordingly.
458 @item Erase Customization
459 This sets the variable to its standard value, and updates the text
460 accordingly. This also eliminates any saved value for the variable,
461 so that you will get the standard value in future Emacs sessions.
463 @item Set to Backup Value
464 This sets the variable to a previous value that was set in the
465 customization buffer in this session. If you customize a variable
466 and then reset it, which discards the customized value,
467 you can get the customized value back again with this operation.
470 @cindex comments on customized options
471 Sometimes it is useful to record a comment about a specific
472 customization. Use the @samp{Add Comment} item from the
473 @samp{[State]} menu to create a field for entering the comment. The
474 comment you enter will be saved, and displayed again if you again view
475 the same variable in a customization buffer, even in another session.
477 The state of a group indicates whether anything in that group has been
478 edited, set or saved.
480 Near the top of the customization buffer there are two lines of buttons:
483 [Set for Current Session] [Save for Future Sessions]
484 [Undo Edits] [Reset to Saved] [Erase Customization] [Finish]
487 @vindex custom-buffer-done-function
489 Invoking @samp{[Finish]} either buries or kills this customization
490 buffer according to the setting of the option
491 @code{custom-buffer-done-kill}; the default is to bury the buffer.
492 Each of the other buttons performs an operation---set, save or
493 reset---on each of the settings in the buffer that could meaningfully
494 be set, saved or reset. They do not operate on settings whose values
495 are hidden, nor on subgroups not visible in the buffer.
497 @node Saving Customizations
498 @subsection Saving Customizations
501 The customization buffer normally saves customizations in
502 @file{~/.emacs}. If you wish, you can save customizations in another
503 file instead. To make this work, your @file{~/.emacs} should set
504 @code{custom-file} to the name of that file. Then you should load the
505 file by calling @code{load}. For example:
508 (setq custom-file "~/.emacs-custom.el")
512 You can also use @code{custom-file} to specify different
513 customization files for different Emacs versions, like this:
516 (cond ((< emacs-major-version 21)
517 ;; @r{Emacs 20 customization.}
518 (setq custom-file "~/.custom-20.el"))
519 ((and (= emacs-major-version 21) (< emacs-minor-version 4))
520 ;; @r{Emacs 21 customization, before version 21.4.}
521 (setq custom-file "~/.custom-21.el"))
522 ((< emacs-major-version 22)
523 ;; @r{Emacs version 21.4 or later.}
524 (setq custom-file "~/.custom-21.4.el"))
526 ;; @r{Emacs version 22.1 or later.}
527 (setq custom-file "~/.custom-22.el")))
532 If Emacs was invoked with the @option{-q} or @option{--no-init-file}
533 options (@pxref{Initial Options}), it will not let you save your
534 customizations in your @file{~/.emacs} init file. This is because
535 saving customizations from such a session would wipe out all the other
536 customizations you might have on your init file.
538 @node Face Customization
539 @subsection Customizing Faces
540 @cindex customizing faces
543 @cindex fonts and faces
545 In addition to variables, some customization groups also include
546 faces. When you show the contents of a group, both the variables and
547 the faces in the group appear in the customization buffer. Here is an
548 example of how a face looks:
551 Custom Changed Face:(sample) [Hide Face]
553 Face used when the customize item has been changed.
554 Parent groups: [Custom Magic Faces]
555 Attributes: [ ] Font Family: *
562 [ ] Strike-through: *
563 [ ] Box around text: *
565 [X] Foreground: white (sample)
566 [X] Background: blue (sample)
571 Each face attribute has its own line. The @samp{[@var{x}]} button
572 before the attribute name indicates whether the attribute is
573 @dfn{enabled}; @samp{[X]} means that it's enabled, and @samp{[ ]}
574 means that it's disabled. You can enable or disable the attribute by
575 clicking that button. When the attribute is enabled, you can change
576 the attribute value in the usual ways.
578 For the colors, you can specify a color name (use @kbd{M-x
579 list-colors-display} for a list of them) or a hexadecimal color
580 specification of the form @samp{#@var{rr}@var{gg}@var{bb}}.
581 (@samp{#000000} is black, @samp{#ff0000} is red, @samp{#00ff00} is
582 green, @samp{#0000ff} is blue, and @samp{#ffffff} is white.) On a
583 black-and-white display, the colors you can use for the background are
584 @samp{black}, @samp{white}, @samp{gray}, @samp{gray1}, and
585 @samp{gray3}. Emacs supports these shades of gray by using background
586 stipple patterns instead of a color.
588 Setting, saving and resetting a face work like the same operations for
589 variables (@pxref{Changing a Variable}).
591 A face can specify different appearances for different types of
592 display. For example, a face can make text red on a color display, but
593 use a bold font on a monochrome display. To specify multiple
594 appearances for a face, select @samp{For All Kinds of Displays} in the
595 menu you get from invoking @samp{[State]}.
598 Another more basic way to set the attributes of a specific face is
599 with @kbd{M-x modify-face}. This command reads the name of a face, then
600 reads the attributes one by one. For the color and stipple attributes,
601 the attribute's current value is the default---type just @key{RET} if
602 you don't want to change that attribute. Type @samp{none} if you want
603 to clear out the attribute.
605 @node Specific Customization
606 @subsection Customizing Specific Items
608 Instead of finding the setting you want to change by navigating the
609 structure of groups, here are other ways to specify the settings that
610 you want to customize.
613 @item M-x customize-variable @key{RET} @var{variable} @key{RET}
614 Set up a customization buffer with just one variable, @var{variable}.
615 @item M-x customize-face @key{RET} @var{face} @key{RET}
616 Set up a customization buffer with just one face, @var{face}.
617 @item M-x customize-group @key{RET} @var{group} @key{RET}
618 Set up a customization buffer with just one group, @var{group}.
619 @item M-x customize-apropos @key{RET} @var{regexp} @key{RET}
620 Set up a customization buffer with all the settings and groups that
622 @item M-x customize-changed-options @key{RET} @var{version} @key{RET}
623 Set up a customization buffer with all the settings and groups
624 whose meaning has changed since Emacs version @var{version}.
625 @item M-x customize-saved
626 Set up a customization buffer containing all settings that you
627 have saved with customization buffers.
628 @item M-x customize-customized
629 Set up a customization buffer containing all settings that you have
630 customized but not saved.
633 @findex customize-variable
634 If you want to alter a particular variable with the customization
635 buffer, and you know its name, you can use the command @kbd{M-x
636 customize-variable} and specify the variable name. This sets up the
637 customization buffer with just one variable---the one that you asked
638 for. Editing, setting and saving the value work as described above,
639 but only for the specified variable. Minibuffer completion is handy
640 if you only know part of the name. However, this command can only see
641 options that have been loaded in the current Emacs session.
643 @findex customize-face
644 Likewise, you can modify a specific face, chosen by name, using
645 @kbd{M-x customize-face}. By default it operates on the face used
646 on the character after point.
648 @findex customize-group
649 You can also set up the customization buffer with a specific group,
650 using @kbd{M-x customize-group}. The immediate contents of the chosen
651 group, including variables, faces, and other groups, all appear
652 as well (even if not already loaded). However, the subgroups' own
653 contents are not included.
655 @findex customize-apropos
656 To control more precisely what to customize, you can use @kbd{M-x
657 customize-apropos}. You specify a regular expression as argument;
658 then all @emph{loaded} settings and groups whose names match this
659 regular expression are set up in the customization buffer. If you
660 specify an empty regular expression, this includes @emph{all} loaded
661 groups and settings---which takes a long time to set up.
663 @findex customize-changed
664 When you upgrade to a new Emacs version, you might want to customize
665 new settings and settings whose meanings or default values have
666 changed. To do this, use @kbd{M-x customize-changed} and
667 specify a previous Emacs version number using the minibuffer. It
668 creates a customization buffer which shows all the settings and groups
669 whose definitions have been changed since the specified version, loading
672 @findex customize-saved
673 @findex customize-customized
674 If you change settings and then decide the change was a mistake, you
675 can use two special commands to revisit your previous changes. Use
676 @kbd{M-x customize-saved} to look at the settings that you have saved.
677 Use @kbd{M-x customize-customized} to look at the settings that you
678 have set but not saved.
681 @subsection Customization Themes
682 @cindex custom themes
684 @dfn{Custom themes} are collections of settings that can be enabled
685 or disabled as a unit. You can use Custom themes to switch quickly
686 and easily between various collections of settings, and to transfer
687 such collections from one computer to another.
689 @findex customize-create-theme
690 To define a Custom theme, use @kbd{M-x customize-create-theme},
691 which brings up a buffer named @samp{*New Custom Theme*}. At the top
692 of the buffer is an editable field where you can specify the name of
693 the theme. Click on the button labelled @samp{Insert Variable} to add
694 a variable to the theme, and click on @samp{Insert Face} to add a
695 face. You can edit these values in the @samp{*New Custom Theme*}
696 buffer like in an ordinary Customize buffer. To remove an option from
697 the theme, click on its @samp{State} button and select @samp{Delete}.
699 @vindex custom-theme-directory
700 After adding the desired options, click on @samp{Save Theme} to save
701 the Custom theme. This writes the theme definition to a file
702 @file{@var{foo}-theme.el} (where @var{foo} is the theme name you
703 supplied), in the directory @file{~/.emacs.d/}. You can specify the
704 directory by setting @code{custom-theme-directory}.
706 You can view and edit the settings of a previously-defined theme by
707 clicking on @samp{Visit Theme} and specifying the theme name. You can
708 also import the variables and faces that you have set using Customize
709 by visiting the ``special'' theme named @samp{user}. This theme, which
710 records all the options that you set in the ordinary customization
711 buffer, is always enabled, and always takes precedence over all other
712 enabled Custom themes. Additionally, the @samp{user} theme is
713 recorded in your @file{.emacs} file, rather than a
714 @file{user-theme.el} file.
716 @vindex custom-enabled-themes
717 Once you have defined a Custom theme, you can use it by customizing
718 the variable @code{custom-enabled-themes}. This is a list of Custom
719 themes that are @dfn{enabled}, or put into effect. If you set
720 @code{custom-enabled-themes} using the Customize interface, the theme
721 definitions are automatically loaded from the theme files, if they
722 aren't already. If you save the value of @code{custom-enabled-themes}
723 for future Emacs sessions, those Custom themes will be enabled
724 whenever Emacs is started up.
726 If two enabled themes specify different values for an option, the
727 theme occurring earlier in @code{custom-enabled-themes} takes effect.
731 @findex disable-theme
732 You can also enable a Custom theme with @kbd{M-x enable-theme}.
733 This prompts for a theme name in the minibuffer, loads the theme from
734 the theme file if necessary, and enables the theme. An enabled theme
735 can be @dfn{disabled} with the command @kbd{M-x disable-theme}; this
736 returns the options specified in the theme to their original values.
737 To re-enable the theme, call @kbd{M-x enable-theme} again. If a theme
738 file is changed during your Emacs session, you can reload it by
739 calling @kbd{M-x load-theme}. This also enables the theme.
747 A @dfn{variable} is a Lisp symbol which has a value. The symbol's
748 name is also called the name of the variable. A variable name can
749 contain any characters that can appear in a file, but conventionally
750 variable names consist of words separated by hyphens. A variable can
751 have a documentation string which describes what kind of value it should
752 have and how the value will be used.
754 Emacs Lisp allows any variable (with a few exceptions) to have any
755 kind of value, but most variables that Emacs uses need a value of a
756 certain type. Often the value should always be a string, or should
757 always be a number. Sometimes we say that a certain feature is turned
758 on if a variable is ``non-@code{nil},'' meaning that if the variable's
759 value is @code{nil}, the feature is off, but the feature is on for
760 @emph{any} other value. The conventional value to use to turn on the
761 feature---since you have to pick one particular value when you set the
762 variable---is @code{t}.
764 Emacs uses many Lisp variables for internal record keeping, but the
765 most interesting variables for a non-programmer user are those meant
766 for users to change---the @dfn{user options}.
768 Each user option that you can set with the customization buffer is
769 in fact a Lisp variable. Emacs does not (usually) change the values
770 of these variables; instead, you set the values, and thereby alter and
771 control the behavior of certain Emacs commands. Use of the
772 customization buffer is explained above (@pxref{Easy Customization});
773 here we describe other aspects of Emacs variables.
776 * Examining:: Examining or setting one variable's value.
777 * Hooks:: Hook variables let you specify programs for parts
778 of Emacs to run on particular occasions.
779 * Locals:: Per-buffer values of variables.
780 * File Variables:: How files can specify variable values.
784 @subsection Examining and Setting Variables
785 @cindex setting variables
788 @item C-h v @var{var} @key{RET}
789 Display the value and documentation of variable @var{var}
790 (@code{describe-variable}).
791 @item M-x set-variable @key{RET} @var{var} @key{RET} @var{value} @key{RET}
792 Change the value of variable @var{var} to @var{value}.
795 To examine the value of a single variable, use @kbd{C-h v}
796 (@code{describe-variable}), which reads a variable name using the
797 minibuffer, with completion. It displays both the value and the
798 documentation of the variable. For example,
801 C-h v fill-column @key{RET}
805 displays something like this:
808 fill-column's value is 70
811 *Column beyond which automatic line-wrapping should happen.
812 Automatically becomes buffer-local when set in any fashion.
816 The star at the beginning of the documentation indicates that this
817 variable is a user option. @kbd{C-h v} is not restricted to user
818 options; it allows any variable name.
821 The most convenient way to set a specific user option variable is
822 with @kbd{M-x set-variable}. This reads the variable name with the
823 minibuffer (with completion), and then reads a Lisp expression for the
824 new value using the minibuffer a second time (you can insert the old
825 value into the minibuffer for editing via @kbd{M-n}). For example,
828 M-x set-variable @key{RET} fill-column @key{RET} 75 @key{RET}
832 sets @code{fill-column} to 75.
834 @kbd{M-x set-variable} is limited to user option variables, but you can
835 set any variable with a Lisp expression, using the function @code{setq}.
836 Here is a @code{setq} expression to set @code{fill-column}:
839 (setq fill-column 75)
842 To execute an expression like this one, go to the @samp{*scratch*}
843 buffer, type in the expression, and then type @kbd{C-j}. @xref{Lisp
846 Setting variables, like all means of customizing Emacs except where
847 otherwise stated, affects only the current Emacs session. The only
848 way to alter the variable in future sessions is to put something in
849 the @file{~/.emacs} file to set it those sessions (@pxref{Init File}).
854 @cindex running a hook
856 @dfn{Hooks} are an important mechanism for customization of Emacs. A
857 hook is a Lisp variable which holds a list of functions, to be called on
858 some well-defined occasion. (This is called @dfn{running the hook}.)
859 The individual functions in the list are called the @dfn{hook functions}
860 of the hook. With rare exceptions, hooks in Emacs are empty when Emacs
861 starts up, so the only hook functions in any given hook are the ones you
862 explicitly put there as customization.
864 Most major modes run one or more @dfn{mode hooks} as the last step of
865 initialization. This makes it easy for you to customize the behavior of
866 the mode, by setting up a hook function to override the local variable
867 assignments already made by the mode. But hooks are also used in other
868 contexts. For example, the hook @code{suspend-hook} runs just before
869 Emacs suspends itself (@pxref{Exiting}).
872 Most Emacs hooks are @dfn{normal hooks}. This means that running the
873 hook operates by calling all the hook functions, unconditionally, with
874 no arguments. We have made an effort to keep most hooks normal so that
875 you can use them in a uniform way. Every variable in Emacs whose name
876 ends in @samp{-hook} is a normal hook.
878 @cindex abnormal hook
879 There are also a few @dfn{abnormal hooks}. These variables' names end
880 in @samp{-hooks} or @samp{-functions}, instead of @samp{-hook}. What
881 makes these hooks abnormal is that there is something peculiar about the
882 way its functions are called---perhaps they are given arguments, or
883 perhaps the values they return are used in some way. For example,
884 @code{find-file-not-found-functions} (@pxref{Visiting}) is abnormal because
885 as soon as one hook function returns a non-@code{nil} value, the rest
886 are not called at all. The documentation of each abnormal hook variable
887 explains in detail what is peculiar about it.
889 You can set a hook variable with @code{setq} like any other Lisp
890 variable, but the recommended way to add a hook function to a hook
891 (either normal or abnormal) is by calling @code{add-hook}. You can
892 specify any valid Lisp function as the hook function, provided it can
893 handle the proper number of arguments (zero arguments, in the case of
894 a normal hook). Of course, not every Lisp function is @emph{useful}
895 in any particular hook.
897 For example, here's how to set up a hook to turn on Auto Fill mode
898 when entering Text mode and other modes based on Text mode:
901 (add-hook 'text-mode-hook 'turn-on-auto-fill)
904 The next example shows how to use a hook to customize the indentation
905 of C code. (People often have strong personal preferences for one
906 format compared to another.) Here the hook function is an anonymous
912 '((c-comment-only-line-offset . 4)
915 (c-cleanup-list . (scope-operator
920 (c-offsets-alist . ((arglist-close . c-lineup-arglist)
921 (substatement-open . 0)))))
925 (add-hook 'c-mode-common-hook
927 (c-add-style "my-style" my-c-style t)))
931 It is best to design your hook functions so that the order in which
932 they are executed does not matter. Any dependence on the order is
933 ``asking for trouble.'' However, the order is predictable: the most
934 recently added hook functions are executed first.
936 If you play with adding various different versions of a hook
937 function by calling @code{add-hook} over and over, remember that all
938 the versions you added will remain in the hook variable together. You
939 can clear out individual functions with @code{remove-hook}, or do
940 @code{(setq @var{hook-variable} nil)} to remove everything.
943 @subsection Local Variables
946 @item M-x make-local-variable @key{RET} @var{var} @key{RET}
947 Make variable @var{var} have a local value in the current buffer.
948 @item M-x kill-local-variable @key{RET} @var{var} @key{RET}
949 Make variable @var{var} use its global value in the current buffer.
950 @item M-x make-variable-buffer-local @key{RET} @var{var} @key{RET}
951 Mark variable @var{var} so that setting it will make it local to the
952 buffer that is current at that time.
955 @cindex local variables
956 Almost any variable can be made @dfn{local} to a specific Emacs
957 buffer. This means that its value in that buffer is independent of its
958 value in other buffers. A few variables are always local in every
959 buffer. Every other Emacs variable has a @dfn{global} value which is in
960 effect in all buffers that have not made the variable local.
962 @findex make-local-variable
963 @kbd{M-x make-local-variable} reads the name of a variable and makes it
964 local to the current buffer. Further changes in this buffer will not
965 affect others, and further changes in the global value will not affect this
968 @findex make-variable-buffer-local
969 @cindex per-buffer variables
970 @kbd{M-x make-variable-buffer-local} reads the name of a variable and
971 changes the future behavior of the variable so that it will become local
972 automatically when it is set. More precisely, once a variable has been
973 marked in this way, the usual ways of setting the variable automatically
974 do @code{make-local-variable} first. We call such variables
975 @dfn{per-buffer} variables.
977 Major modes (@pxref{Major Modes}) always make variables local to the
978 buffer before setting the variables. This is why changing major modes
979 in one buffer has no effect on other buffers. Minor modes also work by
980 setting variables---normally, each minor mode has one controlling
981 variable which is non-@code{nil} when the mode is enabled (@pxref{Minor
982 Modes}). For most minor modes, the controlling variable is per buffer.
984 Emacs contains a number of variables that are always per-buffer.
985 These include @code{abbrev-mode}, @code{auto-fill-function},
986 @code{case-fold-search}, @code{comment-column}, @code{ctl-arrow},
987 @code{fill-column}, @code{fill-prefix}, @code{indent-tabs-mode},
988 @code{left-margin}, @code{mode-line-format}, @code{overwrite-mode},
989 @code{selective-display-ellipses}, @code{selective-display},
990 @code{tab-width}, and @code{truncate-lines}. Some other variables are
991 always local in every buffer, but they are used for internal
994 A few variables cannot be local to a buffer because they are always
995 local to each display instead (@pxref{Multiple Displays}). If you try to
996 make one of these variables buffer-local, you'll get an error message.
998 @findex kill-local-variable
999 @kbd{M-x kill-local-variable} reads the name of a variable and makes
1000 it cease to be local to the current buffer. The global value of the
1001 variable henceforth is in effect in this buffer. Setting the major mode
1002 kills all the local variables of the buffer except for a few variables
1003 specially marked as @dfn{permanent locals}.
1005 @findex setq-default
1006 To set the global value of a variable, regardless of whether the
1007 variable has a local value in the current buffer, you can use the Lisp
1008 construct @code{setq-default}. This construct is used just like
1009 @code{setq}, but it sets variables' global values instead of their local
1010 values (if any). When the current buffer does have a local value, the
1011 new global value may not be visible until you switch to another buffer.
1015 (setq-default fill-column 75)
1019 @code{setq-default} is the only way to set the global value of a variable
1020 that has been marked with @code{make-variable-buffer-local}.
1022 @findex default-value
1023 Lisp programs can use @code{default-value} to look at a variable's
1024 default value. This function takes a symbol as argument and returns its
1025 default value. The argument is evaluated; usually you must quote it
1026 explicitly. For example, here's how to obtain the default value of
1030 (default-value 'fill-column)
1033 @node File Variables
1034 @subsection Local Variables in Files
1035 @cindex local variables in files
1036 @cindex file local variables
1038 A file can specify local variable values for use when you edit the
1039 file with Emacs. Visiting the file checks for local variable
1040 specifications; it automatically makes these variables local to the
1041 buffer, and sets them to the values specified in the file.
1043 There are two ways to specify local variable values: in the first
1044 line, or with a local variables list. Here's how to specify them in the
1048 -*- mode: @var{modename}; @var{var}: @var{value}; @dots{} -*-
1052 You can specify any number of variables/value pairs in this way, each
1053 pair with a colon and semicolon as shown above. @code{mode:
1054 @var{modename};} specifies the major mode; this should come first in the
1055 line. The @var{value}s are not evaluated; they are used literally.
1056 Here is an example that specifies Lisp mode and sets two variables with
1060 ;; -*- mode: Lisp; fill-column: 75; comment-column: 50; -*-
1063 You can also specify the coding system for a file in this way: just
1064 specify a value for the ``variable'' named @code{coding}. The ``value''
1065 must be a coding system name that Emacs recognizes. @xref{Coding
1066 Systems}. @w{@samp{unibyte: t}} specifies unibyte loading for a
1067 particular Lisp file. @xref{Enabling Multibyte}.
1069 The @code{eval} pseudo-variable, described below, can be specified in
1070 the first line as well.
1072 @cindex shell scripts, and local file variables
1073 In shell scripts, the first line is used to identify the script
1074 interpreter, so you cannot put any local variables there. To accommodate
1075 for this, when Emacs visits a shell script, it looks for local variable
1076 specifications in the @emph{second} line.
1078 A @dfn{local variables list} goes near the end of the file, in the
1079 last page. (It is often best to put it on a page by itself.) The local
1080 variables list starts with a line containing the string @samp{Local
1081 Variables:}, and ends with a line containing the string @samp{End:}. In
1082 between come the variable names and values, one set per line, as
1083 @samp{@var{variable}:@: @var{value}}. The @var{value}s are not
1084 evaluated; they are used literally. If a file has both a local
1085 variables list and a @samp{-*-} line, Emacs processes @emph{everything}
1086 in the @samp{-*-} line first, and @emph{everything} in the local
1087 variables list afterward.
1089 Here is an example of a local variables list:
1092 ;;; Local Variables: ***
1094 ;;; comment-column:0 ***
1095 ;;; comment-start: ";;; " ***
1096 ;;; comment-end:"***" ***
1100 As you see, each line starts with the prefix @samp{;;; } and each line
1101 ends with the suffix @samp{ ***}. Emacs recognizes these as the prefix
1102 and suffix based on the first line of the list, by finding them
1103 surrounding the magic string @samp{Local Variables:}; then it
1104 automatically discards them from the other lines of the list.
1106 The usual reason for using a prefix and/or suffix is to embed the
1107 local variables list in a comment, so it won't confuse other programs
1108 that the file is intended as input for. The example above is for a
1109 language where comment lines start with @samp{;;; } and end with
1110 @samp{***}; the local values for @code{comment-start} and
1111 @code{comment-end} customize the rest of Emacs for this unusual
1112 syntax. Don't use a prefix (or a suffix) if you don't need one.
1114 If you write a multi-line string value, you should put the prefix
1115 and suffix on each line, even lines that start or end within the
1116 string. They will be stripped off for processing the list. If you
1117 want to split a long string across multiple lines of the file, you can
1118 use backslash-newline, which is ignored in Lisp string constants.
1119 Here's an example of doing this:
1123 # compile-command: "cc foo.c -Dfoo=bar -Dhack=whatever \
1128 Some ``variable names'' have special meanings in a local variables
1129 list. Specifying the ``variable'' @code{mode} really sets the major
1130 mode, while any value specified for the ``variable'' @code{eval} is
1131 simply evaluated as an expression (its value is ignored). A value for
1132 @code{coding} specifies the coding system for character code
1133 conversion of this file, and a value of @code{t} for @code{unibyte}
1134 says to visit the file in a unibyte buffer. These four ``variables''
1135 are not really variables; setting them in any other context has no
1138 @emph{If @code{mode} is used to set a major mode, it should be the
1139 first ``variable'' in the list.} Otherwise, the entries that precede
1140 it will usually be ignored, since most modes kill all local variables
1141 as part of their initialization.
1143 You can use the @code{mode} ``variable'' to set minor modes as well
1144 as the major modes; in fact, you can use it more than once, first to
1145 set the major mode and then to set minor modes which are specific to
1146 particular buffers. But most minor modes should not be specified in
1147 the file at all, regardless of how, because they represent user
1150 For example, you may be tempted to try to turn on Auto Fill mode with
1151 a local variable list. That is a mistake. The choice of Auto Fill mode
1152 or not is a matter of individual taste, not a matter of the contents of
1153 particular files. If you want to use Auto Fill, set up major mode hooks
1154 with your @file{.emacs} file to turn it on (when appropriate) for you
1155 alone (@pxref{Init File}). Don't use a local variable list to impose
1156 your taste on everyone.
1158 The start of the local variables list must be no more than 3000
1159 characters from the end of the file, and must be in the last page if the
1160 file is divided into pages. Otherwise, Emacs will not notice it is
1161 there. The purpose of this rule is so that a stray @samp{Local
1162 Variables:}@: not in the last page does not confuse Emacs, and so that
1163 visiting a long file that is all one page and has no local variables
1164 list need not take the time to search the whole file.
1166 Use the command @code{normal-mode} to reset the local variables and
1167 major mode of a buffer according to the file name and contents,
1168 including the local variables list if any. @xref{Choosing Modes}.
1170 @findex enable-local-variables
1171 The variable @code{enable-local-variables} controls whether to process
1172 local variables in files, and thus gives you a chance to override them.
1173 Its default value is @code{t}, which means do process local variables in
1174 files. If you set the value to @code{nil}, Emacs simply ignores local
1175 variables in files. Any other value says to query you about each file
1176 that has local variables, showing you the local variable specifications
1179 @findex enable-local-eval
1180 The @code{eval} ``variable,'' and certain actual variables, create a
1181 special risk; when you visit someone else's file, local variable
1182 specifications for these could affect your Emacs in arbitrary ways.
1183 Therefore, the variable @code{enable-local-eval} controls whether Emacs
1184 processes @code{eval} variables, as well variables with names that end
1185 in @samp{-hook}, @samp{-hooks}, @samp{-function} or @samp{-functions},
1186 and certain other variables. The three possibilities for the variable's
1187 value are @code{t}, @code{nil}, and anything else, just as for
1188 @code{enable-local-variables}. The default is @code{maybe}, which is
1189 neither @code{t} nor @code{nil}, so normally Emacs does ask for
1190 confirmation about file settings for these variables.
1192 @findex safe-local-eval-forms
1193 The @code{safe-local-eval-forms} is a customizable list of eval
1194 forms which are safe to eval, so Emacs should not ask for
1195 confirmation to evaluate these forms, even if
1196 @code{enable-local-variables} says to ask for confirmation in general.
1199 @section Customizing Key Bindings
1200 @cindex key bindings
1202 This section describes @dfn{key bindings}, which map keys to commands,
1203 and @dfn{keymaps}, which record key bindings. It also explains how
1204 to customize key bindings.
1206 Recall that a command is a Lisp function whose definition provides for
1207 interactive use. Like every Lisp function, a command has a function
1208 name which usually consists of lower-case letters and hyphens.
1211 * Keymaps:: Generalities. The global keymap.
1212 * Prefix Keymaps:: Keymaps for prefix keys.
1213 * Local Keymaps:: Major and minor modes have their own keymaps.
1214 * Minibuffer Maps:: The minibuffer uses its own local keymaps.
1215 * Rebinding:: How to redefine one key's meaning conveniently.
1216 * Init Rebinding:: Rebinding keys with your init file, @file{.emacs}.
1217 * Function Keys:: Rebinding terminal function keys.
1218 * Named ASCII Chars:: Distinguishing @key{TAB} from @kbd{C-i}, and so on.
1219 * Non-ASCII Rebinding:: Rebinding non-@acronym{ASCII} characters such as Latin-1.
1220 * Mouse Buttons:: Rebinding mouse buttons in Emacs.
1221 * Disabling:: Disabling a command means confirmation is required
1222 before it can be executed. This is done to protect
1223 beginners from surprises.
1230 The bindings between key sequences and command functions are recorded
1231 in data structures called @dfn{keymaps}. Emacs has many of these, each
1232 used on particular occasions.
1234 Recall that a @dfn{key sequence} (@dfn{key}, for short) is a sequence
1235 of @dfn{input events} that have a meaning as a unit. Input events
1236 include characters, function keys and mouse buttons---all the inputs
1237 that you can send to the computer with your terminal. A key sequence
1238 gets its meaning from its @dfn{binding}, which says what command it
1239 runs. The function of keymaps is to record these bindings.
1241 @cindex global keymap
1242 The @dfn{global} keymap is the most important keymap because it is
1243 always in effect. The global keymap defines keys for Fundamental mode;
1244 most of these definitions are common to most or all major modes. Each
1245 major or minor mode can have its own keymap which overrides the global
1246 definitions of some keys.
1248 For example, a self-inserting character such as @kbd{g} is
1249 self-inserting because the global keymap binds it to the command
1250 @code{self-insert-command}. The standard Emacs editing characters such
1251 as @kbd{C-a} also get their standard meanings from the global keymap.
1252 Commands to rebind keys, such as @kbd{M-x global-set-key}, actually work
1253 by storing the new binding in the proper place in the global map.
1256 Meta characters work differently; Emacs translates each Meta
1257 character into a pair of characters starting with @key{ESC}. When you
1258 type the character @kbd{M-a} in a key sequence, Emacs replaces it with
1259 @kbd{@key{ESC} a}. A meta key comes in as a single input event, but
1260 becomes two events for purposes of key bindings. The reason for this is
1261 historical, and we might change it someday.
1263 @cindex function key
1264 Most modern keyboards have function keys as well as character keys.
1265 Function keys send input events just as character keys do, and keymaps
1266 can have bindings for them.
1268 On text terminals, typing a function key actually sends the computer a
1269 sequence of characters; the precise details of the sequence depends on
1270 which function key and on the model of terminal you are using. (Often
1271 the sequence starts with @kbd{@key{ESC} [}.) If Emacs understands your
1272 terminal type properly, it recognizes the character sequences forming
1273 function keys wherever they occur in a key sequence (not just at the
1274 beginning). Thus, for most purposes, you can pretend the function keys
1275 reach Emacs directly and ignore their encoding as character sequences.
1278 Mouse buttons also produce input events. These events come with other
1279 data---the window and position where you pressed or released the button,
1280 and a time stamp. But only the choice of button matters for key
1281 bindings; the other data matters only if a command looks at it.
1282 (Commands designed for mouse invocation usually do look at the other
1285 A keymap records definitions for single events. Interpreting a key
1286 sequence of multiple events involves a chain of keymaps. The first
1287 keymap gives a definition for the first event; this definition is
1288 another keymap, which is used to look up the second event in the
1289 sequence, and so on.
1291 Key sequences can mix function keys and characters. For example,
1292 @kbd{C-x @key{SELECT}} is meaningful. If you make @key{SELECT} a prefix
1293 key, then @kbd{@key{SELECT} C-n} makes sense. You can even mix mouse
1294 events with keyboard events, but we recommend against it, because such
1295 key sequences are inconvenient to use.
1297 As a user, you can redefine any key; but it is usually best to stick
1298 to key sequences that consist of @kbd{C-c} followed by a letter (upper
1299 or lower case). These keys are ``reserved for users,'' so they won't
1300 conflict with any properly designed Emacs extension. The function
1301 keys @key{F5} through @key{F9} are also reserved for users. If you
1302 redefine some other key, your definition may be overridden by certain
1303 extensions or major modes which redefine the same key.
1305 @node Prefix Keymaps
1306 @subsection Prefix Keymaps
1308 A prefix key such as @kbd{C-x} or @key{ESC} has its own keymap,
1309 which holds the definition for the event that immediately follows
1312 The definition of a prefix key is usually the keymap to use for
1313 looking up the following event. The definition can also be a Lisp
1314 symbol whose function definition is the following keymap; the effect is
1315 the same, but it provides a command name for the prefix key that can be
1316 used as a description of what the prefix key is for. Thus, the binding
1317 of @kbd{C-x} is the symbol @code{Control-X-prefix}, whose function
1318 definition is the keymap for @kbd{C-x} commands. The definitions of
1319 @kbd{C-c}, @kbd{C-x}, @kbd{C-h} and @key{ESC} as prefix keys appear in
1320 the global map, so these prefix keys are always available.
1322 Aside from ordinary prefix keys, there is a fictitious ``prefix key''
1323 which represents the menu bar; see @ref{Menu Bar,,,elisp, The Emacs Lisp
1324 Reference Manual}, for special information about menu bar key bindings.
1325 Mouse button events that invoke pop-up menus are also prefix keys; see
1326 @ref{Menu Keymaps,,,elisp, The Emacs Lisp Reference Manual}, for more
1329 Some prefix keymaps are stored in variables with names:
1334 @code{ctl-x-map} is the variable name for the map used for characters that
1338 @code{help-map} is for characters that follow @kbd{C-h}.
1341 @code{esc-map} is for characters that follow @key{ESC}. Thus, all Meta
1342 characters are actually defined by this map.
1345 @code{ctl-x-4-map} is for characters that follow @kbd{C-x 4}.
1347 @vindex mode-specific-map
1348 @code{mode-specific-map} is for characters that follow @kbd{C-c}.
1352 @subsection Local Keymaps
1354 @cindex local keymap
1355 So far we have explained the ins and outs of the global map. Major
1356 modes customize Emacs by providing their own key bindings in @dfn{local
1357 keymaps}. For example, C mode overrides @key{TAB} to make it indent the
1358 current line for C code. Portions of text in the buffer can specify
1359 their own keymaps to substitute for the keymap of the buffer's major
1362 @cindex minor mode keymap
1363 Minor modes can also have local keymaps. Whenever a minor mode is
1364 in effect, the definitions in its keymap override both the major
1365 mode's local keymap and the global keymap.
1368 @vindex lisp-mode-map
1369 The local keymaps for Lisp mode and several other major modes always
1370 exist even when not in use. These are kept in variables named
1371 @code{lisp-mode-map} and so on. For major modes less often used, the
1372 local keymap is normally constructed only when the mode is used for the
1373 first time in a session. This is to save space. If you wish to change
1374 one of these keymaps, you must use the major mode's @dfn{mode
1377 All minor mode keymaps are created in advance. There is no way to
1378 defer their creation until the first time the minor mode is enabled.
1380 A local keymap can locally redefine a key as a prefix key by defining
1381 it as a prefix keymap. If the key is also defined globally as a prefix,
1382 then its local and global definitions (both keymaps) effectively
1383 combine: both of them are used to look up the event that follows the
1384 prefix key. Thus, if the mode's local keymap defines @kbd{C-c} as
1385 another keymap, and that keymap defines @kbd{C-z} as a command, this
1386 provides a local meaning for @kbd{C-c C-z}. This does not affect other
1387 sequences that start with @kbd{C-c}; if those sequences don't have their
1388 own local bindings, their global bindings remain in effect.
1390 Another way to think of this is that Emacs handles a multi-event key
1391 sequence by looking in several keymaps, one by one, for a binding of the
1392 whole key sequence. First it checks the minor mode keymaps for minor
1393 modes that are enabled, then it checks the major mode's keymap, and then
1394 it checks the global keymap. This is not precisely how key lookup
1395 works, but it's good enough for understanding ordinary circumstances.
1397 @cindex rebinding major mode keys
1399 To change the local bindings of a major mode, you must change the
1400 mode's local keymap. Normally you must wait until the first time the
1401 mode is used, because most major modes don't create their keymaps until
1402 then. If you want to specify something in your @file{~/.emacs} file to
1403 change a major mode's bindings, you must use the mode's mode hook to
1404 delay the change until the mode is first used.
1406 For example, the command @code{texinfo-mode} to select Texinfo mode
1407 runs the hook @code{texinfo-mode-hook}. Here's how you can use the hook
1408 to add local bindings (not very useful, we admit) for @kbd{C-c n} and
1409 @kbd{C-c p} in Texinfo mode:
1412 (add-hook 'texinfo-mode-hook
1414 (define-key texinfo-mode-map "\C-cp"
1415 'backward-paragraph)
1416 (define-key texinfo-mode-map "\C-cn"
1417 'forward-paragraph)))
1422 @node Minibuffer Maps
1423 @subsection Minibuffer Keymaps
1425 @cindex minibuffer keymaps
1426 @vindex minibuffer-local-map
1427 @vindex minibuffer-local-ns-map
1428 @vindex minibuffer-local-completion-map
1429 @vindex minibuffer-local-must-match-map
1430 @vindex minibuffer-local-filename-completion-map
1431 @vindex minibuffer-local-must-match-filename-map
1432 The minibuffer has its own set of local keymaps; they contain various
1433 completion and exit commands.
1437 @code{minibuffer-local-map} is used for ordinary input (no completion).
1439 @code{minibuffer-local-ns-map} is similar, except that @key{SPC} exits
1440 just like @key{RET}. This is used mainly for Mocklisp compatibility.
1442 @code{minibuffer-local-completion-map} is for permissive completion.
1444 @code{minibuffer-local-must-match-map} is for strict completion and
1445 for cautious completion.
1447 @code{minibuffer-local-filename-completion-map} and
1448 @code{minibuffer-local-must-match-filename-map} are like the two
1449 previous ones, but they are specifically for file name completion.
1450 They do not bind @key{SPC}.
1454 @subsection Changing Key Bindings Interactively
1455 @cindex key rebinding, this session
1456 @cindex redefining keys, this session
1458 The way to redefine an Emacs key is to change its entry in a keymap.
1459 You can change the global keymap, in which case the change is effective in
1460 all major modes (except those that have their own overriding local
1461 definitions for the same key). Or you can change the current buffer's
1462 local map, which affects all buffers using the same major mode.
1464 @findex global-set-key
1465 @findex local-set-key
1466 @findex global-unset-key
1467 @findex local-unset-key
1469 @item M-x global-set-key @key{RET} @var{key} @var{cmd} @key{RET}
1470 Define @var{key} globally to run @var{cmd}.
1471 @item M-x local-set-key @key{RET} @var{key} @var{cmd} @key{RET}
1472 Define @var{key} locally (in the major mode now in effect) to run
1474 @item M-x global-unset-key @key{RET} @var{key}
1475 Make @var{key} undefined in the global map.
1476 @item M-x local-unset-key @key{RET} @var{key}
1477 Make @var{key} undefined locally (in the major mode now in effect).
1480 For example, suppose you like to execute commands in a subshell within
1481 an Emacs buffer, instead of suspending Emacs and executing commands in
1482 your login shell. Normally, @kbd{C-z} is bound to the function
1483 @code{suspend-emacs} (when not using the X Window System), but you can
1484 change @kbd{C-z} to invoke an interactive subshell within Emacs, by
1485 binding it to @code{shell} as follows:
1488 M-x global-set-key @key{RET} C-z shell @key{RET}
1492 @code{global-set-key} reads the command name after the key. After you
1493 press the key, a message like this appears so that you can confirm that
1494 you are binding the key you want:
1497 Set key C-z to command:
1500 You can redefine function keys and mouse events in the same way; just
1501 type the function key or click the mouse when it's time to specify the
1504 You can rebind a key that contains more than one event in the same
1505 way. Emacs keeps reading the key to rebind until it is a complete key
1506 (that is, not a prefix key). Thus, if you type @kbd{C-f} for
1507 @var{key}, that's the end; the minibuffer is entered immediately to
1508 read @var{cmd}. But if you type @kbd{C-x}, another character is read;
1509 if that is @kbd{4}, another character is read, and so on. For
1513 M-x global-set-key @key{RET} C-x 4 $ spell-other-window @key{RET}
1517 redefines @kbd{C-x 4 $} to run the (fictitious) command
1518 @code{spell-other-window}.
1520 The two-character keys consisting of @kbd{C-c} followed by a letter
1521 are reserved for user customizations. Lisp programs are not supposed to
1522 define these keys, so the bindings you make for them will be available
1523 in all major modes and will never get in the way of anything.
1525 You can remove the global definition of a key with
1526 @code{global-unset-key}. This makes the key @dfn{undefined}; if you
1527 type it, Emacs will just beep. Similarly, @code{local-unset-key} makes
1528 a key undefined in the current major mode keymap, which makes the global
1529 definition (or lack of one) come back into effect in that major mode.
1531 If you have redefined (or undefined) a key and you subsequently wish
1532 to retract the change, undefining the key will not do the job---you need
1533 to redefine the key with its standard definition. To find the name of
1534 the standard definition of a key, go to a Fundamental mode buffer and
1535 use @kbd{C-h c}. The documentation of keys in this manual also lists
1536 their command names.
1538 If you want to prevent yourself from invoking a command by mistake, it
1539 is better to disable the command than to undefine the key. A disabled
1540 command is less work to invoke when you really want to.
1543 @node Init Rebinding
1544 @subsection Rebinding Keys in Your Init File
1546 If you have a set of key bindings that you like to use all the time,
1547 you can specify them in your @file{.emacs} file by using their Lisp
1548 syntax. (@xref{Init File}.)
1550 The simplest method for doing this works for @acronym{ASCII} characters and
1551 Meta-modified @acronym{ASCII} characters only. This method uses a string to
1552 represent the key sequence you want to rebind. For example, here's how
1553 to bind @kbd{C-z} to @code{shell}:
1556 (global-set-key "\C-z" 'shell)
1560 This example uses a string constant containing one character,
1561 @kbd{C-z}. (@samp{\C-} is string syntax for a control character.) The
1562 single-quote before the command name, @code{shell}, marks it as a
1563 constant symbol rather than a variable. If you omit the quote, Emacs
1564 would try to evaluate @code{shell} immediately as a variable. This
1565 probably causes an error; it certainly isn't what you want.
1567 Here is another example that binds the key sequence @kbd{C-x M-l}:
1570 (global-set-key "\C-x\M-l" 'make-symbolic-link)
1573 To put @key{TAB}, @key{RET}, @key{ESC}, or @key{DEL} in the
1574 string, you can use the Emacs Lisp escape sequences, @samp{\t},
1575 @samp{\r}, @samp{\e}, and @samp{\d}. Here is an example which binds
1576 @kbd{C-x @key{TAB}}:
1579 (global-set-key "\C-x\t" 'indent-rigidly)
1582 These examples show how to write some other special @acronym{ASCII} characters
1583 in strings for key bindings:
1586 (global-set-key "\r" 'newline) ;; @key{RET}
1587 (global-set-key "\d" 'delete-backward-char) ;; @key{DEL}
1588 (global-set-key "\C-x\e\e" 'repeat-complex-command) ;; @key{ESC}
1591 When the key sequence includes function keys or mouse button events,
1592 or non-@acronym{ASCII} characters such as @code{C-=} or @code{H-a}, you must use
1593 the more general method of rebinding, which uses a vector to specify the
1596 The way to write a vector in Emacs Lisp is with square brackets around
1597 the vector elements. Use spaces to separate the elements. If an
1598 element is a symbol, simply write the symbol's name---no other
1599 delimiters or punctuation are needed. If a vector element is a
1600 character, write it as a Lisp character constant: @samp{?} followed by
1601 the character as it would appear in a string.
1603 Here are examples of using vectors to rebind @kbd{C-=} (a control
1604 character not in @acronym{ASCII}), @kbd{C-M-=} (not in @acronym{ASCII} because @kbd{C-=}
1605 is not), @kbd{H-a} (a Hyper character; @acronym{ASCII} doesn't have Hyper at
1606 all), @key{F7} (a function key), and @kbd{C-Mouse-1} (a
1607 keyboard-modified mouse button):
1610 (global-set-key [?\C-=] 'make-symbolic-link)
1611 (global-set-key [?\M-\C-=] 'make-symbolic-link)
1612 (global-set-key [?\H-a] 'make-symbolic-link)
1613 (global-set-key [f7] 'make-symbolic-link)
1614 (global-set-key [C-mouse-1] 'make-symbolic-link)
1617 You can use a vector for the simple cases too. Here's how to
1618 rewrite the first six examples above to use vectors:
1621 (global-set-key [?\C-z] 'shell)
1622 (global-set-key [?\C-x ?l] 'make-symbolic-link)
1623 (global-set-key [?\C-x ?\t] 'indent-rigidly)
1624 (global-set-key [?\r] 'newline)
1625 (global-set-key [?\d] 'delete-backward-char)
1626 (global-set-key [?\C-x ?\e ?\e] 'repeat-complex-command)
1630 As you see, you represent a multi-character key sequence with a vector
1631 by listing all of the characters in order within the square brackets that
1634 Language and coding systems can cause problems with key bindings
1635 for non-@acronym{ASCII} characters. @xref{Non-ASCII Rebinding}.
1638 @subsection Rebinding Function Keys
1640 Key sequences can contain function keys as well as ordinary
1641 characters. Just as Lisp characters (actually integers) represent
1642 keyboard characters, Lisp symbols represent function keys. If the
1643 function key has a word as its label, then that word is also the name of
1644 the corresponding Lisp symbol. Here are the conventional Lisp names for
1645 common function keys:
1648 @item @code{left}, @code{up}, @code{right}, @code{down}
1651 @item @code{begin}, @code{end}, @code{home}, @code{next}, @code{prior}
1652 Other cursor repositioning keys.
1654 @item @code{select}, @code{print}, @code{execute}, @code{backtab}
1655 @itemx @code{insert}, @code{undo}, @code{redo}, @code{clearline}
1656 @itemx @code{insertline}, @code{deleteline}, @code{insertchar}, @code{deletechar}
1657 Miscellaneous function keys.
1659 @item @code{f1}, @code{f2}, @dots{} @code{f35}
1660 Numbered function keys (across the top of the keyboard).
1662 @item @code{kp-add}, @code{kp-subtract}, @code{kp-multiply}, @code{kp-divide}
1663 @itemx @code{kp-backtab}, @code{kp-space}, @code{kp-tab}, @code{kp-enter}
1664 @itemx @code{kp-separator}, @code{kp-decimal}, @code{kp-equal}
1665 Keypad keys (to the right of the regular keyboard), with names or punctuation.
1667 @item @code{kp-0}, @code{kp-1}, @dots{} @code{kp-9}
1668 Keypad keys with digits.
1670 @item @code{kp-f1}, @code{kp-f2}, @code{kp-f3}, @code{kp-f4}
1674 These names are conventional, but some systems (especially when using
1675 X) may use different names. To make certain what symbol is used for a
1676 given function key on your terminal, type @kbd{C-h c} followed by that
1679 A key sequence which contains function key symbols (or anything but
1680 @acronym{ASCII} characters) must be a vector rather than a string.
1681 Thus, to bind function key @samp{f1} to the command @code{rmail},
1682 write the following:
1685 (global-set-key [f1] 'rmail)
1689 To bind the right-arrow key to the command @code{forward-char}, you can
1690 use this expression:
1693 (global-set-key [right] 'forward-char)
1697 This uses the Lisp syntax for a vector containing the symbol
1698 @code{right}. (This binding is present in Emacs by default.)
1700 @xref{Init Rebinding}, for more information about using vectors for
1703 You can mix function keys and characters in a key sequence. This
1704 example binds @kbd{C-x @key{NEXT}} to the command @code{forward-page}.
1707 (global-set-key [?\C-x next] 'forward-page)
1711 where @code{?\C-x} is the Lisp character constant for the character
1712 @kbd{C-x}. The vector element @code{next} is a symbol and therefore
1713 does not take a question mark.
1715 You can use the modifier keys @key{CTRL}, @key{META}, @key{HYPER},
1716 @key{SUPER}, @key{ALT} and @key{SHIFT} with function keys. To represent
1717 these modifiers, add the strings @samp{C-}, @samp{M-}, @samp{H-},
1718 @samp{s-}, @samp{A-} and @samp{S-} at the front of the symbol name.
1719 Thus, here is how to make @kbd{Hyper-Meta-@key{RIGHT}} move forward a
1723 (global-set-key [H-M-right] 'forward-word)
1727 Many keyboards have a ``numeric keypad'' on the right hand side.
1728 The numeric keys in the keypad double up as cursor motion keys,
1729 toggled by a key labeled @samp{Num Lock}. By default, Emacs
1730 translates these keys to the corresponding keys in the main keyboard.
1731 For example, when @samp{Num Lock} is on, the key labeled @samp{8} on
1732 the numeric keypad produces @code{kp-8}, which is translated to
1733 @kbd{8}; when @samp{Num Lock} is off, the same key produces
1734 @code{kp-up}, which is translated to @key{UP}. If you rebind a key
1735 such as @kbd{8} or @key{UP}, it affects the equivalent keypad key too.
1736 However, if you rebind a @samp{kp-} key directly, that won't affect
1737 its non-keypad equivalent.
1739 Emacs provides a convenient method for binding the numeric keypad
1740 keys, using the variables @code{keypad-setup},
1741 @code{keypad-numlock-setup}, @code{keypad-shifted-setup}, and
1742 @code{keypad-numlock-shifted-setup}. These can be found in the
1743 @samp{keyboard} customization group (@pxref{Easy Customization}). You
1744 can rebind the keys to perform other tasks, such as issuing numeric
1747 @node Named ASCII Chars
1748 @subsection Named @acronym{ASCII} Control Characters
1750 @key{TAB}, @key{RET}, @key{BS}, @key{LFD}, @key{ESC} and @key{DEL}
1751 started out as names for certain @acronym{ASCII} control characters,
1752 used so often that they have special keys of their own. For instance,
1753 @key{TAB} was another name for @kbd{C-i}. Later, users found it
1754 convenient to distinguish in Emacs between these keys and the ``same''
1755 control characters typed with the @key{CTRL} key. Therefore, on most
1756 modern terminals, they are no longer the same, and @key{TAB} is
1757 distinguishable from @kbd{C-i}.
1759 Emacs can distinguish these two kinds of input if the keyboard does.
1760 It treats the ``special'' keys as function keys named @code{tab},
1761 @code{return}, @code{backspace}, @code{linefeed}, @code{escape}, and
1762 @code{delete}. These function keys translate automatically into the
1763 corresponding @acronym{ASCII} characters @emph{if} they have no
1764 bindings of their own. As a result, neither users nor Lisp programs
1765 need to pay attention to the distinction unless they care to.
1767 If you do not want to distinguish between (for example) @key{TAB} and
1768 @kbd{C-i}, make just one binding, for the @acronym{ASCII} character @key{TAB}
1769 (octal code 011). If you do want to distinguish, make one binding for
1770 this @acronym{ASCII} character, and another for the ``function key'' @code{tab}.
1772 With an ordinary @acronym{ASCII} terminal, there is no way to distinguish
1773 between @key{TAB} and @kbd{C-i} (and likewise for other such pairs),
1774 because the terminal sends the same character in both cases.
1776 @node Non-ASCII Rebinding
1777 @subsection Non-@acronym{ASCII} Characters on the Keyboard
1778 @cindex rebinding non-@acronym{ASCII} keys
1779 @cindex non-@acronym{ASCII} keys, binding
1781 If your keyboard has keys that send non-@acronym{ASCII}
1782 characters, such as accented letters, rebinding these keys
1783 must be done by using a vector like this@footnote{Note that
1784 you should avoid the string syntax for binding
1785 non-@acronym{ASCII} characters, since they will be
1786 interpreted as meta keys. @xref{Strings of Events,,,elisp,
1787 The Emacs Lisp Reference Manual}.}:
1790 (global-set-key [?@var{char}] 'some-function)
1794 Type @kbd{C-q} followed by the key you want to bind, to insert @var{char}.
1796 Since this puts a non-@acronym{ASCII} character in the @file{.emacs},
1797 you should specify a coding system for that file that supports the
1798 character in question. @xref{Init Syntax}.
1800 @strong{Warning:} if you change the keyboard encoding, or change
1801 between multibyte and unibyte mode, or anything that would alter which
1802 code @kbd{C-q} would insert for that character, you'll need to edit
1803 the Lisp expression accordingly, to use the character code generated
1804 by @kbd{C-q} in the new mode.
1807 @subsection Rebinding Mouse Buttons
1808 @cindex mouse button events
1809 @cindex rebinding mouse buttons
1810 @cindex click events
1813 @cindex button down events
1815 Emacs uses Lisp symbols to designate mouse buttons, too. The ordinary
1816 mouse events in Emacs are @dfn{click} events; these happen when you
1817 press a button and release it without moving the mouse. You can also
1818 get @dfn{drag} events, when you move the mouse while holding the button
1819 down. Drag events happen when you finally let go of the button.
1821 The symbols for basic click events are @code{mouse-1} for the leftmost
1822 button, @code{mouse-2} for the next, and so on. Here is how you can
1823 redefine the second mouse button to split the current window:
1826 (global-set-key [mouse-2] 'split-window-vertically)
1829 The symbols for drag events are similar, but have the prefix
1830 @samp{drag-} before the word @samp{mouse}. For example, dragging the
1831 first button generates a @code{drag-mouse-1} event.
1833 You can also define bindings for events that occur when a mouse button
1834 is pressed down. These events start with @samp{down-} instead of
1835 @samp{drag-}. Such events are generated only if they have key bindings.
1836 When you get a button-down event, a corresponding click or drag event
1839 @cindex double clicks
1840 @cindex triple clicks
1841 If you wish, you can distinguish single, double, and triple clicks. A
1842 double click means clicking a mouse button twice in approximately the
1843 same place. The first click generates an ordinary click event. The
1844 second click, if it comes soon enough, generates a double-click event
1845 instead. The event type for a double-click event starts with
1846 @samp{double-}: for example, @code{double-mouse-3}.
1848 This means that you can give a special meaning to the second click at
1849 the same place, but it must act on the assumption that the ordinary
1850 single click definition has run when the first click was received.
1852 This constrains what you can do with double clicks, but user interface
1853 designers say that this constraint ought to be followed in any case. A
1854 double click should do something similar to the single click, only
1855 ``more so.'' The command for the double-click event should perform the
1856 extra work for the double click.
1858 If a double-click event has no binding, it changes to the
1859 corresponding single-click event. Thus, if you don't define a
1860 particular double click specially, it executes the single-click command
1863 Emacs also supports triple-click events whose names start with
1864 @samp{triple-}. Emacs does not distinguish quadruple clicks as event
1865 types; clicks beyond the third generate additional triple-click events.
1866 However, the full number of clicks is recorded in the event list, so
1867 if you know Emacs Lisp you can distinguish if you really want to
1868 (@pxref{Accessing Events,,, elisp, The Emacs Lisp Reference Manual}).
1869 We don't recommend distinct meanings for more than three clicks, but
1870 sometimes it is useful for subsequent clicks to cycle through the same
1871 set of three meanings, so that four clicks are equivalent to one
1872 click, five are equivalent to two, and six are equivalent to three.
1874 Emacs also records multiple presses in drag and button-down events.
1875 For example, when you press a button twice, then move the mouse while
1876 holding the button, Emacs gets a @samp{double-drag-} event. And at the
1877 moment when you press it down for the second time, Emacs gets a
1878 @samp{double-down-} event (which is ignored, like all button-down
1879 events, if it has no binding).
1881 @vindex double-click-time
1882 The variable @code{double-click-time} specifies how much time can
1883 elapse between clicks and still allow them to be grouped as a multiple
1884 click. Its value is in units of milliseconds. If the value is
1885 @code{nil}, double clicks are not detected at all. If the value is
1886 @code{t}, then there is no time limit. The default is 500.
1888 @vindex double-click-fuzz
1889 The variable @code{double-click-fuzz} specifies how much the mouse
1890 can move between clicks and still allow them to be grouped as a multiple
1891 click. Its value is in units of pixels on windowed displays and in
1892 units of 1/8 of a character cell on text-mode terminals; the default is
1895 The symbols for mouse events also indicate the status of the modifier
1896 keys, with the usual prefixes @samp{C-}, @samp{M-}, @samp{H-},
1897 @samp{s-}, @samp{A-} and @samp{S-}. These always precede @samp{double-}
1898 or @samp{triple-}, which always precede @samp{drag-} or @samp{down-}.
1900 A frame includes areas that don't show text from the buffer, such as
1901 the mode line and the scroll bar. You can tell whether a mouse button
1902 comes from a special area of the screen by means of dummy ``prefix
1903 keys.'' For example, if you click the mouse in the mode line, you get
1904 the prefix key @code{mode-line} before the ordinary mouse-button symbol.
1905 Thus, here is how to define the command for clicking the first button in
1906 a mode line to run @code{scroll-up}:
1909 (global-set-key [mode-line mouse-1] 'scroll-up)
1912 Here is the complete list of these dummy prefix keys and their
1917 The mouse was in the mode line of a window.
1919 The mouse was in the vertical line separating side-by-side windows. (If
1920 you use scroll bars, they appear in place of these vertical lines.)
1921 @item vertical-scroll-bar
1922 The mouse was in a vertical scroll bar. (This is the only kind of
1923 scroll bar Emacs currently supports.)
1925 The mouse was in the menu bar.
1927 The mouse was in a header line.
1929 @item horizontal-scroll-bar
1930 The mouse was in a horizontal scroll bar. Horizontal scroll bars do
1931 horizontal scrolling, and people don't use them often.
1935 You can put more than one mouse button in a key sequence, but it isn't
1939 @subsection Disabling Commands
1940 @cindex disabled command
1942 Disabling a command marks the command as requiring confirmation before it
1943 can be executed. The purpose of disabling a command is to prevent
1944 beginning users from executing it by accident and being confused.
1946 An attempt to invoke a disabled command interactively in Emacs
1947 displays a window containing the command's name, its documentation, and
1948 some instructions on what to do immediately; then Emacs asks for input
1949 saying whether to execute the command as requested, enable it and
1950 execute it, or cancel. If you decide to enable the command, you are
1951 asked whether to do this permanently or just for the current session.
1952 (Enabling permanently works by automatically editing your @file{.emacs}
1953 file.) You can also type @kbd{!} to enable @emph{all} commands,
1954 for the current session only.
1956 The direct mechanism for disabling a command is to put a
1957 non-@code{nil} @code{disabled} property on the Lisp symbol for the
1958 command. Here is the Lisp program to do this:
1961 (put 'delete-region 'disabled t)
1964 If the value of the @code{disabled} property is a string, that string
1965 is included in the message displayed when the command is used:
1968 (put 'delete-region 'disabled
1969 "It's better to use `kill-region' instead.\n")
1972 @findex disable-command
1973 @findex enable-command
1974 You can make a command disabled either by editing the @file{.emacs}
1975 file directly or with the command @kbd{M-x disable-command}, which edits
1976 the @file{.emacs} file for you. Likewise, @kbd{M-x enable-command}
1977 edits @file{.emacs} to enable a command permanently. @xref{Init File}.
1979 If Emacs was invoked with the @option{-q} or @option{--no-init-file}
1980 options (@pxref{Initial Options}), it will not edit your
1981 @file{~/.emacs} init file. This is because editing the init file from
1982 such a session might overwrite the lines you might have on your init
1983 file which enable and disable commands.
1985 Whether a command is disabled is independent of what key is used to
1986 invoke it; disabling also applies if the command is invoked using
1987 @kbd{M-x}. Disabling a command has no effect on calling it as a
1988 function from Lisp programs.
1991 @section The Syntax Table
1992 @cindex syntax table
1994 All the Emacs commands which parse words or balance parentheses are
1995 controlled by the @dfn{syntax table}. The syntax table says which
1996 characters are opening delimiters, which are parts of words, which are
1997 string quotes, and so on. It does this by assigning each character to
1998 one of fifteen-odd @dfn{syntax classes}. In some cases it specifies
1999 some additional information also.
2001 Each major mode has its own syntax table (though related major modes
2002 sometimes share one syntax table) which it installs in each buffer
2003 that uses the mode. The syntax table installed in the current buffer
2004 is the one that all commands use, so we call it ``the'' syntax table.
2007 @findex describe-syntax
2008 To display a description of the contents of the current syntax
2009 table, type @kbd{C-h s} (@code{describe-syntax}). The description of
2010 each character includes both the string you would have to give to
2011 @code{modify-syntax-entry} to set up that character's current syntax,
2012 starting with the character which designates its syntax class, plus
2013 some English text to explain its meaning.
2015 A syntax table is actually a Lisp object, a char-table, whose
2016 elements are cons cells. For full information on the syntax table,
2017 see @ref{Syntax Tables,, Syntax Tables, elisp, The Emacs Lisp
2021 @section The Init File, @file{~/.emacs}
2023 @cindex Emacs initialization file
2024 @cindex key rebinding, permanent
2025 @cindex rebinding keys, permanently
2026 @cindex startup (init file)
2028 When Emacs is started, it normally loads a Lisp program from the
2029 file @file{.emacs} or @file{.emacs.el} in your home directory. We
2030 call this file your @dfn{init file} because it specifies how to
2031 initialize Emacs for you. You can use the command line switch
2032 @samp{-q} to prevent loading your init file, and @samp{-u} (or
2033 @samp{--user}) to specify a different user's init file (@pxref{Initial
2036 You can also use @file{~/.emacs.d/init.el} as the init file. Emacs
2037 tries this if it cannot find @file{~/.emacs} or @file{~/.emacs.el}.
2039 @cindex @file{default.el}, the default init file
2040 There can also be a @dfn{default init file}, which is the library
2041 named @file{default.el}, found via the standard search path for
2042 libraries. The Emacs distribution contains no such library; your site
2043 may create one for local customizations. If this library exists, it is
2044 loaded whenever you start Emacs (except when you specify @samp{-q}).
2045 But your init file, if any, is loaded first; if it sets
2046 @code{inhibit-default-init} non-@code{nil}, then @file{default} is not
2049 @cindex site init file
2050 @cindex @file{site-start.el}, the site startup file
2051 Your site may also have a @dfn{site startup file}; this is named
2052 @file{site-start.el}, if it exists. Like @file{default.el}, Emacs
2053 finds this file via the standard search path for Lisp libraries.
2054 Emacs loads this library before it loads your init file. To inhibit
2055 loading of this library, use the option @samp{--no-site-file}.
2056 @xref{Initial Options}. We recommend against using
2057 @file{site-start.el} for changes that some users may not like. It is
2058 better to put them in @file{default.el}, so that users can more easily
2061 You can place @file{default.el} and @file{site-start.el} in any of
2062 the directories which Emacs searches for Lisp libraries. The variable
2063 @code{load-path} (@pxref{Lisp Libraries}) specifies these directories.
2064 Many sites put these files in the @file{site-lisp} subdirectory of the
2065 Emacs installation directory, typically
2066 @file{/usr/local/share/emacs/site-lisp}.
2068 If you have a large amount of code in your @file{.emacs} file, you
2069 should rename it to @file{~/.emacs.el}, and byte-compile it. @xref{Byte
2070 Compilation,, Byte Compilation, elisp, the Emacs Lisp Reference Manual},
2071 for more information about compiling Emacs Lisp programs.
2073 If you are going to write actual Emacs Lisp programs that go beyond
2074 minor customization, you should read the @cite{Emacs Lisp Reference Manual}.
2076 @xref{Top, Emacs Lisp, Emacs Lisp, elisp, the Emacs Lisp Reference
2081 * Init Syntax:: Syntax of constants in Emacs Lisp.
2082 * Init Examples:: How to do some things with an init file.
2083 * Terminal Init:: Each terminal type can have an init file.
2084 * Find Init:: How Emacs finds the init file.
2088 @subsection Init File Syntax
2090 The @file{.emacs} file contains one or more Lisp function call
2091 expressions. Each of these consists of a function name followed by
2092 arguments, all surrounded by parentheses. For example, @code{(setq
2093 fill-column 60)} calls the function @code{setq} to set the variable
2094 @code{fill-column} (@pxref{Filling}) to 60.
2096 You can set any Lisp variable with @code{setq}, but with certain
2097 variables @code{setq} won't do what you probably want in the
2098 @file{.emacs} file. Some variables automatically become buffer-local
2099 when set with @code{setq}; what you want in @file{.emacs} is to set
2100 the default value, using @code{setq-default}. Some customizable minor
2101 mode variables do special things to enable the mode when you set them
2102 with Customize, but ordinary @code{setq} won't do that; to enable the
2103 mode in your @file{.emacs} file, call the minor mode command. The
2104 following section has examples of both of these methods.
2106 The second argument to @code{setq} is an expression for the new
2107 value of the variable. This can be a constant, a variable, or a
2108 function call expression. In @file{.emacs}, constants are used most
2109 of the time. They can be:
2113 Numbers are written in decimal, with an optional initial minus sign.
2116 @cindex Lisp string syntax
2117 @cindex string syntax
2118 Lisp string syntax is the same as C string syntax with a few extra
2119 features. Use a double-quote character to begin and end a string constant.
2121 In a string, you can include newlines and special characters literally.
2122 But often it is cleaner to use backslash sequences for them: @samp{\n}
2123 for newline, @samp{\b} for backspace, @samp{\r} for carriage return,
2124 @samp{\t} for tab, @samp{\f} for formfeed (control-L), @samp{\e} for
2125 escape, @samp{\\} for a backslash, @samp{\"} for a double-quote, or
2126 @samp{\@var{ooo}} for the character whose octal code is @var{ooo}.
2127 Backslash and double-quote are the only characters for which backslash
2128 sequences are mandatory.
2130 @samp{\C-} can be used as a prefix for a control character, as in
2131 @samp{\C-s} for @acronym{ASCII} control-S, and @samp{\M-} can be used as a prefix for
2132 a Meta character, as in @samp{\M-a} for @kbd{Meta-A} or @samp{\M-\C-a} for
2133 @kbd{Control-Meta-A}.@refill
2135 @cindex international characters in @file{.emacs}
2136 @cindex non-@acronym{ASCII} characters in @file{.emacs}
2137 If you want to include non-@acronym{ASCII} characters in strings in your init
2138 file, you should consider putting a @w{@samp{-*-coding:
2139 @var{coding-system}-*-}} tag on the first line which states the coding
2140 system used to save your @file{.emacs}, as explained in @ref{Recognize
2141 Coding}. This is because the defaults for decoding non-@acronym{ASCII} text might
2142 not yet be set up by the time Emacs reads those parts of your init file
2143 which use such strings, possibly leading Emacs to decode those strings
2147 Lisp character constant syntax consists of a @samp{?} followed by
2148 either a character or an escape sequence starting with @samp{\}.
2149 Examples: @code{?x}, @code{?\n}, @code{?\"}, @code{?\)}. Note that
2150 strings and characters are not interchangeable in Lisp; some contexts
2151 require one and some contexts require the other.
2153 @xref{Non-ASCII Rebinding}, for information about binding commands to
2154 keys which send non-@acronym{ASCII} characters.
2157 @code{t} stands for `true'.
2160 @code{nil} stands for `false'.
2162 @item Other Lisp objects:
2163 Write a single-quote (@code{'}) followed by the Lisp object you want.
2167 @subsection Init File Examples
2169 Here are some examples of doing certain commonly desired things with
2174 Make @key{TAB} in C mode just insert a tab if point is in the middle of a
2178 (setq c-tab-always-indent nil)
2181 Here we have a variable whose value is normally @code{t} for `true'
2182 and the alternative is @code{nil} for `false'.
2185 Make searches case sensitive by default (in all buffers that do not
2189 (setq-default case-fold-search nil)
2192 This sets the default value, which is effective in all buffers that do
2193 not have local values for the variable. Setting @code{case-fold-search}
2194 with @code{setq} affects only the current buffer's local value, which
2195 is not what you probably want to do in an init file.
2198 @vindex user-mail-address
2199 Specify your own email address, if Emacs can't figure it out correctly.
2202 (setq user-mail-address "coon@@yoyodyne.com")
2205 Various Emacs packages that need your own email address use the value of
2206 @code{user-mail-address}.
2209 Make Text mode the default mode for new buffers.
2212 (setq default-major-mode 'text-mode)
2215 Note that @code{text-mode} is used because it is the command for
2216 entering Text mode. The single-quote before it makes the symbol a
2217 constant; otherwise, @code{text-mode} would be treated as a variable
2222 Set up defaults for the Latin-1 character set
2223 which supports most of the languages of Western Europe.
2226 (set-language-environment "Latin-1")
2231 Turn off Line Number mode, a global minor mode.
2234 (line-number-mode 0)
2239 Turn on Auto Fill mode automatically in Text mode and related modes.
2242 (add-hook 'text-mode-hook
2243 '(lambda () (auto-fill-mode 1)))
2246 This shows how to add a hook function to a normal hook variable
2247 (@pxref{Hooks}). The function we supply is a list starting with
2248 @code{lambda}, with a single-quote in front of it to make it a list
2249 constant rather than an expression.
2251 It's beyond the scope of this manual to explain Lisp functions, but for
2252 this example it is enough to know that the effect is to execute
2253 @code{(auto-fill-mode 1)} when Text mode is entered. You can replace
2254 that with any other expression that you like, or with several
2255 expressions in a row.
2257 Emacs comes with a function named @code{turn-on-auto-fill} whose
2258 definition is @code{(lambda () (auto-fill-mode 1))}. Thus, a simpler
2259 way to write the above example is as follows:
2262 (add-hook 'text-mode-hook 'turn-on-auto-fill)
2266 Load the installed Lisp library named @file{foo} (actually a file
2267 @file{foo.elc} or @file{foo.el} in a standard Emacs directory).
2273 When the argument to @code{load} is a relative file name, not starting
2274 with @samp{/} or @samp{~}, @code{load} searches the directories in
2275 @code{load-path} (@pxref{Lisp Libraries}).
2278 Load the compiled Lisp file @file{foo.elc} from your home directory.
2284 Here an absolute file name is used, so no searching is done.
2287 @cindex loading Lisp libraries automatically
2288 @cindex autoload Lisp libraries
2289 Tell Emacs to find the definition for the function @code{myfunction}
2290 by loading a Lisp library named @file{mypackage} (i.e.@: a file
2291 @file{mypackage.elc} or @file{mypackage.el}):
2294 (autoload 'myfunction "mypackage" "Do what I say." t)
2298 Here the string @code{"Do what I say."} is the function's
2299 documentation string. You specify it in the @code{autoload}
2300 definition so it will be available for help commands even when the
2301 package is not loaded. The last argument, @code{t}, indicates that
2302 this function is interactive; that is, it can be invoked interactively
2303 by typing @kbd{M-x myfunction @key{RET}} or by binding it to a key.
2304 If the function is not interactive, omit the @code{t} or use
2308 Rebind the key @kbd{C-x l} to run the function @code{make-symbolic-link}
2309 (@pxref{Init Rebinding}).
2312 (global-set-key "\C-xl" 'make-symbolic-link)
2318 (define-key global-map "\C-xl" 'make-symbolic-link)
2321 Note once again the single-quote used to refer to the symbol
2322 @code{make-symbolic-link} instead of its value as a variable.
2325 Do the same thing for Lisp mode only.
2328 (define-key lisp-mode-map "\C-xl" 'make-symbolic-link)
2332 Redefine all keys which now run @code{next-line} in Fundamental mode
2333 so that they run @code{forward-line} instead.
2335 @findex substitute-key-definition
2337 (substitute-key-definition 'next-line 'forward-line
2342 Make @kbd{C-x C-v} undefined.
2345 (global-unset-key "\C-x\C-v")
2348 One reason to undefine a key is so that you can make it a prefix.
2349 Simply defining @kbd{C-x C-v @var{anything}} will make @kbd{C-x C-v} a
2350 prefix, but @kbd{C-x C-v} must first be freed of its usual non-prefix
2354 Make @samp{$} have the syntax of punctuation in Text mode.
2355 Note the use of a character constant for @samp{$}.
2358 (modify-syntax-entry ?\$ "." text-mode-syntax-table)
2362 Enable the use of the command @code{narrow-to-region} without confirmation.
2365 (put 'narrow-to-region 'disabled nil)
2369 Adjusting the configuration to various platforms and Emacs versions.
2371 Users typically want Emacs to behave the same on all systems, so the
2372 same init file is right for all platforms. However, sometimes it
2373 happens that a function you use for customizing Emacs is not available
2374 on some platforms or in older Emacs versions. To deal with that
2375 situation, put the customization inside a conditional that tests whether
2376 the function or facility is available, like this:
2379 (if (fboundp 'blink-cursor-mode)
2380 (blink-cursor-mode 0))
2382 (if (boundp 'coding-category-utf-8)
2383 (set-coding-priority '(coding-category-utf-8)))
2387 You can also simply disregard the errors that occur if the
2388 function is not defined.
2392 (set-face-background 'region "grey75")
2396 A @code{setq} on a variable which does not exist is generally
2397 harmless, so those do not need a conditional.
2401 @subsection Terminal-specific Initialization
2403 Each terminal type can have a Lisp library to be loaded into Emacs when
2404 it is run on that type of terminal. For a terminal type named
2405 @var{termtype}, the library is called @file{term/@var{termtype}} and it is
2406 found by searching the directories @code{load-path} as usual and trying the
2407 suffixes @samp{.elc} and @samp{.el}. Normally it appears in the
2408 subdirectory @file{term} of the directory where most Emacs libraries are
2411 The usual purpose of the terminal-specific library is to map the
2412 escape sequences used by the terminal's function keys onto more
2413 meaningful names, using @code{function-key-map}. See the file
2414 @file{term/lk201.el} for an example of how this is done. Many function
2415 keys are mapped automatically according to the information in the
2416 Termcap data base; the terminal-specific library needs to map only the
2417 function keys that Termcap does not specify.
2419 When the terminal type contains a hyphen, only the part of the name
2420 before the first hyphen is significant in choosing the library name.
2421 Thus, terminal types @samp{aaa-48} and @samp{aaa-30-rv} both use
2422 the library @file{term/aaa}. The code in the library can use
2423 @code{(getenv "TERM")} to find the full terminal type name.@refill
2425 @vindex term-file-prefix
2426 The library's name is constructed by concatenating the value of the
2427 variable @code{term-file-prefix} and the terminal type. Your @file{.emacs}
2428 file can prevent the loading of the terminal-specific library by setting
2429 @code{term-file-prefix} to @code{nil}.
2431 @vindex term-setup-hook
2432 Emacs runs the hook @code{term-setup-hook} at the end of
2433 initialization, after both your @file{.emacs} file and any
2434 terminal-specific library have been read in. Add hook functions to this
2435 hook if you wish to override part of any of the terminal-specific
2436 libraries and to define initializations for terminals that do not have a
2437 library. @xref{Hooks}.
2440 @subsection How Emacs Finds Your Init File
2442 Normally Emacs uses the environment variable @env{HOME} to find
2443 @file{.emacs}; that's what @samp{~} means in a file name. If
2444 @file{.emacs} is not found inside @file{~/} (nor @file{.emacs.el}),
2445 Emacs looks for @file{~/.emacs.d/init.el} (which, like
2446 @file{~/.emacs.el}, can be byte-compiled).
2448 However, if you run Emacs from a shell started by @code{su}, Emacs
2449 tries to find your own @file{.emacs}, not that of the user you are
2450 currently pretending to be. The idea is that you should get your own
2451 editor customizations even if you are running as the super user.
2453 More precisely, Emacs first determines which user's init file to use.
2454 It gets the user name from the environment variables @env{LOGNAME} and
2455 @env{USER}; if neither of those exists, it uses effective user-ID.
2456 If that user name matches the real user-ID, then Emacs uses @env{HOME};
2457 otherwise, it looks up the home directory corresponding to that user
2458 name in the system's data base of users.
2459 @c LocalWords: backtab
2462 arch-tag: c68abddb-4410-4fb5-925f-63394e971d93