1 @c This is part of the Emacs manual.
2 @c Copyright (C) 1985-1987, 1993-1995, 1997, 2000-2012
3 @c Free Software Foundation, Inc.
4 @c See file emacs.texi for copying conditions.
9 This chapter describes some simple methods to customize the behavior
12 Apart from the methods described here, see @ref{X Resources} for
13 information about using X resources to customize Emacs, and see
14 @ref{Keyboard Macros} for information about recording and replaying
15 keyboard macros. Making more far-reaching and open-ended changes
16 involves writing Emacs Lisp code; see
18 @cite{The Emacs Lisp Reference Manual}.
21 @ref{Top, Emacs Lisp, Emacs Lisp, elisp, The Emacs Lisp
26 * Easy Customization:: Convenient way to browse and change settings.
27 * Variables:: Many Emacs commands examine Emacs variables
28 to decide what to do; by setting variables,
29 you can control their functioning.
30 * Key Bindings:: The keymaps say what command each key runs.
31 By changing them, you can "redefine keys".
32 * Init File:: How to write common customizations in the
36 @node Easy Customization
37 @section Easy Customization Interface
41 @cindex customizable variable
42 Emacs has many @dfn{settings} which you can change. Most settings
43 are @dfn{customizable variables} (@pxref{Variables}), which are also
44 called @dfn{user options}. There is a huge number of customizable
45 variables, controlling numerous aspects of Emacs behavior; the
46 variables documented in this manual are listed in @ref{Variable
47 Index}. A separate class of settings are the @dfn{faces}, which
48 determine the fonts, colors, and other attributes of text
52 @cindex customization buffer
53 To browse and alter settings (both variables and faces), type
54 @kbd{M-x customize}. This creates a @dfn{customization buffer}, which
55 lets you navigate through a logically organized list of settings, edit
56 and set their values, and save them permanently.
59 * Customization Groups:: How settings are classified.
60 * Browsing Custom:: Browsing and searching for settings.
61 * Changing a Variable:: How to edit an option's value and set the option.
62 * Saving Customizations:: Saving customizations for future Emacs sessions.
63 * Face Customization:: How to edit the attributes of a face.
64 * Specific Customization:: Customizing specific settings or groups.
65 * Custom Themes:: Collections of customization settings.
66 * Creating Custom Themes:: How to create a new custom theme.
69 @node Customization Groups
70 @subsection Customization Groups
71 @cindex customization groups
73 Customization settings are organized into @dfn{customization
74 groups}. These groups are collected into bigger groups, all the way
75 up to a master group called @code{Emacs}.
77 @kbd{M-x customize} creates a customization buffer that shows the
78 top-level @code{Emacs} group. It looks like this, in part:
80 @c we want the buffer example to all be on one page, but unfortunately
81 @c that's quite a bit of text, so force all space to the bottom.
85 To apply changes, use the Save or Set buttons.
86 For details, see [Saving Customizations] in the [Emacs manual].
88 ________________________________________ [ Search ]
90 Operate on all settings in this buffer:
91 [ Set for current session ] [ Save for future sessions ]
92 [ Undo edits ] [ Reset to saved ] [ Erase customizations ] [ Exit ]
95 Emacs group: Customization of the One True Editor.
96 [State]: visible group members are all at standard values.
99 [Editing] : Basic text editing facilities.
101 [Convenience] : Convenience features for faster editing.
103 @var{more second-level groups}
108 The main part of this buffer shows the @samp{Emacs} customization
109 group, which contains several other groups (@samp{Editing},
110 @samp{Convenience}, etc.). The contents of those groups are not
111 listed here, only one line of documentation each.
113 The @dfn{state} of the group indicates whether setting in that group
114 has been edited, set or saved. @xref{Changing a Variable}.
116 @cindex editable fields (customization buffer)
117 @cindex buttons (customization buffer)
118 @cindex links (customization buffer)
119 Most of the customization buffer is read-only, but it includes some
120 @dfn{editable fields} that you can edit. For example, at the top of
121 the customization buffer is an editable field for searching for
122 settings (@pxref{Browsing Custom}). There are also @dfn{buttons} and
123 @dfn{links}, which you can activate by either clicking with the mouse,
124 or moving point there and typing @key{RET}. For example, the group
125 names like @samp{[Editing]} are links; activating one of these links
126 brings up the customization buffer for that group.
128 @kindex TAB @r{(customization buffer)}
129 @kindex S-TAB @r{(customization buffer)}
130 @findex widget-forward
131 @findex widget-backward
132 In the customizable buffer, you can type @key{TAB}
133 (@code{widget-forward}) to move forward to the next button or editable
134 field. @kbd{S-@key{TAB}} (@code{widget-backward}) moves back to the
135 previous button or editable field.
137 @node Browsing Custom
138 @subsection Browsing and Searching for Settings
139 @findex customize-browse
141 From the top-level customization buffer created by @kbd{M-x
142 customize}, you can follow the links to the subgroups of the
143 @samp{Emacs} customization group. These subgroups may contain
144 settings for you to customize; they may also contain further subgroups,
145 dealing with yet more specialized subsystems of Emacs. As you
146 navigate the hierarchy of customization groups, you should find some
147 settings that you want to customize.
149 If you are interested in customizing a particular setting or
150 customization group, you can go straight there with the commands
151 @kbd{M-x customize-option}, @kbd{M-x customize-face}, or @kbd{M-x
152 customize-group}. @xref{Specific Customization}.
154 @vindex custom-search-field
155 If you don't know exactly what groups or settings you want to
156 customize, you can search for them using the editable search field at
157 the top of each customization buffer. Here, you can type in a search
158 term---either one or more words separated by spaces, or a regular
159 expression (@pxref{Regexps}). Then type @key{RET} in the field, or
160 activate the @samp{Search} button next to it, to switch to a
161 customization buffer containing groups and settings that match those
162 terms. Note, however, that this feature only finds groups and
163 settings that are loaded in the current Emacs session.
165 If you don't want customization buffers to show the search field,
166 change the variable @code{custom-search-field} to @code{nil}.
168 The command @kbd{M-x customize-apropos} is similar to using the
169 search field, except that it reads the search term(s) using the
170 minibuffer. @xref{Specific Customization}.
172 @kbd{M-x customize-browse} is another way to browse the available
173 settings. This command creates a special customization buffer which
174 shows only the names of groups and settings, in a structured layout.
175 You can show the contents of a group, in the same buffer, by invoking
176 the @samp{[+]} button next to the group name. When the group contents
177 are shown, the button changes to @samp{[-]}; invoking that hides the
178 group contents again. Each group or setting in this buffer has a link
179 which says @samp{[Group]}, @samp{[Option]} or @samp{[Face]}. Invoking
180 this link creates an ordinary customization buffer showing just that
181 group, option, or face; this is the way to change settings that you
182 find with @kbd{M-x customize-browse}.
184 @node Changing a Variable
185 @subsection Changing a Variable
187 Here is an example of what a variable, or user option, looks like in
188 the customization buffer:
191 [Hide] Kill Ring Max: 60
193 Maximum length of kill ring before oldest elements are thrown away.
196 The first line shows that the variable is named
197 @code{kill-ring-max}, formatted as @samp{Kill Ring Max} for easier
198 viewing. Its value is @samp{60}. The button labeled @samp{[Hide]},
199 if activated, hides the variable's value and state; this is useful to
200 avoid cluttering up the customization buffer with very long values
201 (for this reason, variables that have very long values may start out
202 hidden). If you use the @samp{[Hide]} button, it changes to
203 @samp{[Show Value]}, which you can activate to reveal the value and
204 state. On a graphical display, the @samp{[Hide]} and @samp{[Show
205 Value]} buttons are replaced with graphical triangles pointing
206 downwards and rightwards respectively.
208 The line after the variable name indicates the @dfn{customization
209 state} of the variable: in this example, @samp{STANDARD} means you
210 have not changed the variable, so its value is the default one. The
211 @samp{[State]} button gives a menu of operations for customizing the
214 Below the customization state is the documentation for the variable.
215 This is the same documentation that would be shown by the @kbd{C-h v}
216 command (@pxref{Examining}). If the documentation is more than one
217 line long, only one line may be shown. If so, that line ends with a
218 @samp{[More]} button; activate this to see the full documentation.
220 @cindex user options, changing
221 @cindex customizing variables
222 @cindex variables, changing
223 To enter a new value for @samp{Kill Ring Max}, just move point to
224 the value and edit it. For example, type @kbd{M-d} to delete the
225 @samp{60} and type in another number. As you begin to alter the text,
226 the @samp{[State]} line will change:
229 [State]: EDITED, shown value does not take effect until you
234 Editing the value does not make it take effect right away. To do
235 that, you must @dfn{set} the variable by activating the @samp{[State]}
236 button and choosing @samp{Set for Current Session}. Then the
237 variable's state becomes:
240 [State]: SET for current session only.
244 You don't have to worry about specifying a value that is not valid;
245 the @samp{Set for Current Session} operation checks for validity and
246 will not install an unacceptable value.
248 @kindex M-TAB @r{(customization buffer)}
249 @kindex C-M-i @r{(customization buffer)}
250 @findex widget-complete
251 While editing certain kinds of values, such as file names, directory
252 names, and Emacs command names, you can perform completion with
253 @kbd{C-M-i} (@code{widget-complete}), or the equivalent keys
254 @kbd{M-@key{TAB}} or @kbd{@key{ESC} @key{TAB}}. This behaves much
255 like minibuffer completion (@pxref{Completion}).
257 Typing @key{RET} on an editable value field moves point forward to
258 the next field or button, like @key{TAB}. You can thus type @key{RET}
259 when you are finished editing a field, to move on to the next button
260 or field. To insert a newline within an editable field, use @kbd{C-o}
263 For some variables, there is only a fixed set of legitimate values,
264 and you are not allowed to edit the value directly. Instead, a
265 @samp{[Value Menu]} button appears before the value; activating this
266 button presents a choice of values. For a boolean ``on or off''
267 value, the button says @samp{[Toggle]}, and flips the value. After
268 using the @samp{[Value Menu]} or @samp{[Toggle]} button, you must
269 again set the variable to make the chosen value take effect.
271 Some variables have values with complex structure. For example, the
272 value of @code{minibuffer-frame-alist} is an association list. Here
273 is how it appears in the customization buffer:
276 [Hide] Minibuffer Frame Alist:
277 [INS] [DEL] Parameter: width
279 [INS] [DEL] Parameter: height
283 Alist of parameters for the initial minibuffer frame. [Hide]
284 @r{[@dots{}more lines of documentation@dots{}]}
288 In this case, each association in the list consists of two items, one
289 labeled @samp{Parameter} and one labeled @samp{Value}; both are
290 editable fields. You can delete an association from the list with the
291 @samp{[DEL]} button next to it. To add an association, use the
292 @samp{[INS]} button at the position where you want to insert it; the
293 very last @samp{[INS]} button inserts at the end of the list.
295 @cindex saving a setting
296 @cindex settings, how to save
297 When you set a variable, the new value takes effect only in the
298 current Emacs session. To @dfn{save} the value for future sessions,
299 use the @samp{[State]} button and select the @samp{Save for Future
300 Sessions} operation. @xref{Saving Customizations}.
302 You can also restore the variable to its standard value by using the
303 @samp{[State]} button and selecting the @samp{Erase Customization}
304 operation. There are actually four reset operations:
308 If you have modified but not yet set the variable, this restores the
309 text in the customization buffer to match the actual value.
312 This restores the value of the variable to the last saved value,
313 and updates the text accordingly.
315 @item Erase Customization
316 This sets the variable to its standard value. Any saved value that
317 you have is also eliminated.
319 @item Set to Backup Value
320 This sets the variable to a previous value that was set in the
321 customization buffer in this session. If you customize a variable
322 and then reset it, which discards the customized value,
323 you can get the discarded value back again with this operation.
326 @cindex comments on customized settings
327 Sometimes it is useful to record a comment about a specific
328 customization. Use the @samp{Add Comment} item from the
329 @samp{[State]} menu to create a field for entering the comment.
331 Near the top of the customization buffer are two lines of buttons:
334 [Set for Current Session] [Save for Future Sessions]
335 [Undo Edits] [Reset to Saved] [Erase Customization] [Exit]
339 Each of the first five buttons performs the stated operation---set,
340 save, reset, etc.---on all the settings in the buffer that could
341 meaningfully be affected. They do not operate on settings that are
342 hidden, nor on subgroups that are hidden or not visible in the buffer.
344 @kindex C-c C-c @r{(customization buffer)}
345 @kindex C-x C-c @r{(customization buffer)}
348 The command @kbd{C-c C-c} (@code{Custom-set}) is equivalent using to
349 the @samp{[Set for Current Session]} button. The command @kbd{C-x
350 C-s} (@code{Custom-save}) is like using the @samp{[Save for Future
353 @vindex custom-buffer-done-kill
354 The @samp{[Exit]} button switches out of the customization buffer,
355 and buries the buffer at the bottom of the buffer list. To make it
356 kill the customization buffer instead, change the variable
357 @code{custom-buffer-done-kill} to @code{t}.
359 @node Saving Customizations
360 @subsection Saving Customizations
362 In the customization buffer, you can @dfn{save} a customization
363 setting by choosing the @samp{Save for Future Sessions} choice from
364 its @samp{[State]} button. The @kbd{C-x C-s} (@code{Custom-save})
365 command, or the @samp{[Save for Future Sessions]} button at the top of
366 the customization buffer, saves all applicable settings in the buffer.
368 Saving works by writing code to a file, usually your initialization
369 file (@pxref{Init File}). Future Emacs sessions automatically read
370 this file at startup, which sets up the customizations again.
373 You can choose to save customizations somewhere other than your
374 initialization file. To make this work, you must add a couple of
375 lines of code to your initialization file, to set the variable
376 @code{custom-file} to the name of the desired file, and to load that
380 (setq custom-file "~/.emacs-custom.el")
384 You can even specify different customization files for different
385 Emacs versions, like this:
388 (cond ((< emacs-major-version 22)
389 ;; @r{Emacs 21 customization.}
390 (setq custom-file "~/.custom-21.el"))
391 ((and (= emacs-major-version 22)
392 (< emacs-minor-version 3))
393 ;; @r{Emacs 22 customization, before version 22.3.}
394 (setq custom-file "~/.custom-22.el"))
396 ;; @r{Emacs version 22.3 or later.}
397 (setq custom-file "~/.emacs-custom.el")))
402 If Emacs was invoked with the @option{-q} or @option{--no-init-file}
403 options (@pxref{Initial Options}), it will not let you save your
404 customizations in your initialization file. This is because saving
405 customizations from such a session would wipe out all the other
406 customizations you might have on your initialization file.
408 @node Face Customization
409 @subsection Customizing Faces
410 @cindex customizing faces
411 @cindex faces, customizing
412 @cindex fonts and faces
414 You can customize faces (@pxref{Faces}), which determine how Emacs
415 displays different types of text. Customization groups can contain
416 both variables and faces.
418 For example, in programming language modes, source code comments are
419 shown with @code{font-lock-comment-face} (@pxref{Font Lock}). In a
420 customization buffer, that face appears like this:
423 [Hide] Font Lock Comment Face:[sample]
425 Font Lock mode face used to highlight comments.
434 [ ] Strike-through: --
435 [ ] Box around text: --
436 [ ] Inverse-video: --
437 [X] Foreground: Firebrick [Choose] (sample)
441 [Hide Unused Attributes]
445 The first three lines show the name, @samp{[State]} button, and
446 documentation for the face. Below that is a list of @dfn{face
447 attributes}. In front of each attribute is a checkbox. A filled
448 checkbox, @samp{[X]}, means that the face specifies a value for this
449 attribute; an empty checkbox, @samp{[ ]}, means that the face does not
450 specify any special value for the attribute. You can activate a
451 checkbox to specify or unspecify its attribute.
453 Most faces only specify a few attributes (in the above example,
454 @code{font-lock-comment-face} only specifies the foreground color).
455 Emacs has a special face, @code{default}, whose attributes are all
456 specified; it determines the attributes left unspecified by other
459 The @samp{Hide Unused Attributes} button, at the end of the
460 attribute list, hides the unspecified attributes of the face. When
461 attributes are being hidden, the button changes to @samp{[Show All
462 Attributes]}, which reveals the entire attribute list. The
463 customization buffer may start out with unspecified attributes hidden,
464 to avoid cluttering the interface.
466 When an attribute is specified, you can change its value in the
469 Foreground and background colors can be specified using either color
470 names or RGB triplets (@pxref{Colors}). You can also use the
471 @samp{[Choose]} button to switch to a list of color names; select a
472 color with @key{RET} in that buffer to put the color name in the value
475 Setting, saving and resetting a face work like the same operations for
476 variables (@pxref{Changing a Variable}).
478 A face can specify different appearances for different types of
479 displays. For example, a face can make text red on a color display,
480 but use a bold font on a monochrome display. To specify multiple
481 appearances for a face, select @samp{For All Kinds of Displays} in the
482 menu you get from invoking @samp{[State]}.
484 @node Specific Customization
485 @subsection Customizing Specific Items
488 @item M-x customize-option @key{RET} @var{option} @key{RET}
489 @itemx M-x customize-variable @key{RET} @var{option} @key{RET}
490 Set up a customization buffer for just one user option, @var{option}.
491 @item M-x customize-face @key{RET} @var{face} @key{RET}
492 Set up a customization buffer for just one face, @var{face}.
493 @item M-x customize-group @key{RET} @var{group} @key{RET}
494 Set up a customization buffer for just one group, @var{group}.
495 @item M-x customize-apropos @key{RET} @var{regexp} @key{RET}
496 Set up a customization buffer for all the settings and groups that
498 @item M-x customize-changed @key{RET} @var{version} @key{RET}
499 Set up a customization buffer with all the settings and groups
500 whose meaning has changed since Emacs version @var{version}.
501 @item M-x customize-saved
502 Set up a customization buffer containing all settings that you
503 have saved with customization buffers.
504 @item M-x customize-unsaved
505 Set up a customization buffer containing all settings that you have
509 @findex customize-option
510 If you want to customize a particular user option, type @kbd{M-x
511 customize-option}. This reads the variable name, and sets up the
512 customization buffer with just that one user option. When entering
513 the variable name into the minibuffer, completion is available, but
514 only for the names of variables that have been loaded into Emacs.
516 @findex customize-face
517 @findex customize-group
518 Likewise, you can customize a specific face using @kbd{M-x
519 customize-face}. You can set up a customization buffer for a specific
520 customization group using @kbd{M-x customize-group}.
522 @findex customize-apropos
523 @kbd{M-x customize-apropos} prompts for a search term---either one
524 or more words separated by spaces, or a regular expression---and sets
525 up a customization buffer for all @emph{loaded} settings and groups
526 with matching names. This is like using the search field at the top
527 of the customization buffer (@pxref{Customization Groups}).
529 @findex customize-changed
530 When you upgrade to a new Emacs version, you might want to consider
531 customizing new settings, and settings whose meanings or default
532 values have changed. To do this, use @kbd{M-x customize-changed} and
533 specify a previous Emacs version number using the minibuffer. It
534 creates a customization buffer which shows all the settings and groups
535 whose definitions have been changed since the specified version,
536 loading them if necessary.
538 @findex customize-saved
539 @findex customize-unsaved
540 If you change settings and then decide the change was a mistake, you
541 can use two commands to revisit your changes. Use @kbd{M-x
542 customize-saved} to customize settings that you have saved. Use
543 @kbd{M-x customize-unsaved} to customize settings that you have set
547 @subsection Custom Themes
548 @cindex custom themes
550 @dfn{Custom themes} are collections of settings that can be enabled
551 or disabled as a unit. You can use Custom themes to switch easily
552 between various collections of settings, and to transfer such
553 collections from one computer to another.
555 A Custom theme is stored an Emacs Lisp source file. If the name of
556 the Custom theme is @var{name}, the theme file is named
557 @file{@var{name}-theme.el}. @xref{Creating Custom Themes}, for the
558 format of a theme file and how to make one.
560 @findex customize-themes
561 @vindex custom-theme-directory
563 Type @kbd{M-x customize-themes} to switch to a buffer named
564 @file{*Custom Themes*}, which lists the Custom themes that Emacs knows
565 about. By default, Emacs looks for theme files in two locations: the
566 directory specified by the variable @code{custom-theme-directory}
567 (which defaults to @file{~/.emacs.d/}), and a directory named
568 @file{etc/themes} in your Emacs installation (see the variable
569 @code{data-directory}). The latter contains several Custom themes
570 which are distributed with Emacs, which customize Emacs's faces to fit
571 various color schemes. (Note, however, that Custom themes need not be
572 restricted to this purpose; they can be used to customize variables
575 @vindex custom-theme-load-path
576 If you want Emacs to look for Custom themes in some other directory,
577 add the directory name to the list variable
578 @code{custom-theme-load-path}. Its default value is
579 @code{(custom-theme-directory t)}; here, the symbol
580 @code{custom-theme-directory} has the special meaning of the value of
581 the variable @code{custom-theme-directory}, while @code{t} stands for
582 the built-in theme directory @file{etc/themes}. The themes listed in
583 the @file{*Custom Themes*} buffer are those found in the directories
584 specified by @code{custom-theme-load-path}.
586 @kindex C-x C-s @r{(Custom Themes buffer)}
587 In the @file{*Custom Themes*} buffer, you can activate the checkbox
588 next to a Custom theme to enable or disable the theme for the current
589 Emacs session. When a Custom theme is enabled, all of its settings
590 (variables and faces) take effect in the Emacs session. To apply the
591 choice of theme(s) to future Emacs sessions, type @kbd{C-x C-s}
592 (@code{custom-theme-save}) or use the @samp{[Save Theme Settings]}
595 @vindex custom-safe-themes
596 When you first enable a Custom theme, Emacs displays the contents of
597 the theme file and asks if you really want to load it. Because
598 loading a Custom theme can execute arbitrary Lisp code, you should
599 only say yes if you know that the theme is safe; in that case, Emacs
600 offers to remember in the future that the theme is safe (this is done
601 by saving the theme file's SHA-256 hash to the variable
602 @code{custom-safe-themes}; if you want to treat all themes as safe,
603 change its value to @code{t}). Themes that come with Emacs (in the
604 @file{etc/themes} directory) are exempt from this check, and are
605 always considered safe.
607 @vindex custom-enabled-themes
608 Setting or saving Custom themes actually works by customizing the
609 variable @code{custom-enabled-themes}. The value of this variable is
610 a list of Custom theme names (as Lisp symbols, e.g.@: @code{tango}).
611 Instead of using the @file{*Custom Themes*} buffer to set
612 @code{custom-enabled-themes}, you can customize the variable using the
613 usual customization interface, e.g.@: with @kbd{M-x customize-option}.
614 Note that Custom themes are not allowed to set
615 @code{custom-enabled-themes} themselves.
617 Any customizations that you make through the customization buffer
618 take precedence over theme settings. This lets you easily override
619 individual theme settings that you disagree with. If settings from
620 two different themes overlap, the theme occurring earlier in
621 @code{custom-enabled-themes} takes precedence. In the customization
622 buffer, if a setting has been changed from its default by a Custom
623 theme, its @samp{State} display shows @samp{THEMED} instead of
628 @findex disable-theme
629 You can enable a specific Custom theme in the current Emacs session
630 by typing @kbd{M-x load-theme}. This prompts for a theme name, loads
631 the theme from the theme file, and enables it. If a theme file
632 has been loaded before, you can enable the theme without loading its
633 file by typing @kbd{M-x enable-theme}. To disable a Custom theme,
634 type @kbd{M-x disable-theme}.
636 @findex describe-theme
637 To see a description of a Custom theme, type @kbd{?} on its line in
638 the @file{*Custom Themes*} buffer; or type @kbd{M-x describe-theme}
639 anywhere in Emacs and enter the theme name.
641 @node Creating Custom Themes
642 @subsection Creating Custom Themes
643 @cindex custom themes, creating
645 @findex customize-create-theme
646 You can define a Custom theme using an interface similar to the
647 customization buffer, by typing @kbd{M-x customize-create-theme}.
648 This switches to a buffer named @file{*Custom Theme*}. It also offers
649 to insert some common Emacs faces into the theme (a convenience, since
650 Custom themes are often used to customize faces). If you answer no,
651 the theme will initially contain no settings.
653 Near the top of the @file{*Custom Theme*} buffer are editable fields
654 where you can enter the theme's name and description. The name can be
655 anything except @samp{user}. The description is the one that will be
656 shown when you invoke @kbd{M-x describe-theme} for the theme. Its
657 first line should be a brief one-sentence summary; in the buffer made
658 by @kbd{M-x customize-themes}, this sentence is displayed next to the
661 To add a new setting to the theme, use the @samp{[Insert Additional
662 Face]} or @samp{[Insert Additional Variable]} buttons. Each button
663 reads a face or variable name using the minibuffer, with completion,
664 and inserts a customization entry for the face or variable. You can
665 edit the variable values or face attributes in the same way as in a
666 normal customization buffer. To remove a face or variable from the
667 theme, uncheck the checkbox next to its name.
669 @vindex custom-theme-directory
670 After specifying the Custom theme's faces and variables, type
671 @kbd{C-x C-s} (@code{custom-theme-write}) or use the buffer's
672 @samp{[Save Theme]} button. This saves the theme file, named
673 @file{@var{name}-theme.el} where @var{name} is the theme name, in the
674 directory named by @code{custom-theme-directory}.
676 From the @file{*Custom Theme*} buffer, you can view and edit an
677 existing Custom theme by activating the @samp{[Visit Theme]} button
678 and specifying the theme name. You can also add the settings of
679 another theme into the buffer, using the @samp{[Merge Theme]} button.
680 You can import your non-theme settings into a Custom theme by using
681 the @samp{[Merge Theme]} button and specifying the special theme named
684 A theme file is simply an Emacs Lisp source file, and loading the
685 Custom theme works by loading the Lisp file. Therefore, you can edit
686 a theme file directly instead of using the @file{*Custom Theme*}
687 buffer. @xref{Custom Themes,,, elisp, The Emacs Lisp Reference
688 Manual}, for details.
694 A @dfn{variable} is a Lisp symbol which has a value. The symbol's
695 name is also called the @dfn{variable name}. A variable name can
696 contain any characters that can appear in a file, but most variable
697 names consist of ordinary words separated by hyphens.
699 The name of the variable serves as a compact description of its
700 role. Most variables also have a @dfn{documentation string}, which
701 describes what the variable's purpose is, what kind of value it should
702 have, and how the value will be used. You can view this documentation
703 using the help command @kbd{C-h v} (@code{describe-variable}).
706 Emacs uses many Lisp variables for internal record keeping, but the
707 most interesting variables for a non-programmer user are those meant
708 for users to change---these are called @dfn{customizable variables} or
709 @dfn{user options} (@pxref{Easy Customization}). In the following
710 sections, we will describe other aspects of Emacs variables, such as
711 how to set them outside Customize.
713 Emacs Lisp allows any variable (with a few exceptions) to have any
714 kind of value. However, many variables are meaningful only if
715 assigned values of a certain type. For example, only numbers are
716 meaningful values for @code{kill-ring-max}, which specifies the
717 maximum length of the kill ring (@pxref{Earlier Kills}); if you give
718 @code{kill-ring-max} a string value, commands such as @kbd{C-y}
719 (@code{yank}) will signal an error. On the other hand, some variables
720 don't care about type; for instance, if a variable has one effect for
721 @code{nil} values and another effect for ``non-@code{nil}'' values,
722 then any value that is not the symbol @code{nil} induces the second
723 effect, regardless of its type (by convention, we usually use the
724 value @code{t}---a symbol which stands for ``true''---to specify a
725 non-@code{nil} value). If you set a variable using the customization
726 buffer, you need not worry about giving it an invalid type: the
727 customization buffer usually only allows you to enter meaningful
728 values. When in doubt, use @kbd{C-h v} (@code{describe-variable}) to
729 check the variable's documentation string to see kind of value it
730 expects (@pxref{Examining}).
733 * Examining:: Examining or setting one variable's value.
734 * Hooks:: Hook variables let you specify programs for parts
735 of Emacs to run on particular occasions.
736 * Locals:: Per-buffer values of variables.
737 * File Variables:: How files can specify variable values.
738 * Directory Variables:: How variable values can be specified by directory.
742 @subsection Examining and Setting Variables
743 @cindex setting variables
746 @item C-h v @var{var} @key{RET}
747 Display the value and documentation of variable @var{var}
748 (@code{describe-variable}).
749 @item M-x set-variable @key{RET} @var{var} @key{RET} @var{value} @key{RET}
750 Change the value of variable @var{var} to @var{value}.
753 To examine the value of a variable, use @kbd{C-h v}
754 (@code{describe-variable}). This reads a variable name using the
755 minibuffer, with completion, and displays both the value and the
756 documentation of the variable. For example,
759 C-h v fill-column @key{RET}
763 displays something like this:
766 fill-column is a variable defined in `C source code'.
767 fill-column's value is 70
769 Automatically becomes buffer-local when set in any fashion.
770 This variable is safe as a file local variable if its value
771 satisfies the predicate `integerp'.
774 Column beyond which automatic line-wrapping should happen.
775 Interactively, you can set the local value with C-x f.
777 You can customize this variable.
781 The line that says ``You can customize the variable'' indicates that
782 this variable is a user option. @kbd{C-h v} is not restricted to user
783 options; it allows non-customizable variables too.
786 The most convenient way to set a specific customizable variable is
787 with @kbd{M-x set-variable}. This reads the variable name with the
788 minibuffer (with completion), and then reads a Lisp expression for the
789 new value using the minibuffer a second time (you can insert the old
790 value into the minibuffer for editing via @kbd{M-n}). For example,
793 M-x set-variable @key{RET} fill-column @key{RET} 75 @key{RET}
797 sets @code{fill-column} to 75.
799 @kbd{M-x set-variable} is limited to customizable variables, but you
800 can set any variable with a Lisp expression like this:
803 (setq fill-column 75)
807 To execute such an expression, type @kbd{M-:} (@code{eval-expression})
808 and enter the expression in the minibuffer (@pxref{Lisp Eval}).
809 Alternatively, go to the @file{*scratch*} buffer, type in the
810 expression, and then type @kbd{C-j} (@pxref{Lisp Interaction}).
812 Setting variables, like all means of customizing Emacs except where
813 otherwise stated, affects only the current Emacs session. The only
814 way to alter the variable in future sessions is to put something in
815 your initialization file (@pxref{Init File}).
820 @cindex running a hook
822 @dfn{Hooks} are an important mechanism for customizing Emacs. A
823 hook is a Lisp variable which holds a list of functions, to be called
824 on some well-defined occasion. (This is called @dfn{running the
825 hook}.) The individual functions in the list are called the @dfn{hook
826 functions} of the hook. For example, the hook @code{kill-emacs-hook}
827 runs just before exiting Emacs (@pxref{Exiting}).
830 Most hooks are @dfn{normal hooks}. This means that when Emacs runs
831 the hook, it calls each hook function in turn, with no arguments. We
832 have made an effort to keep most hooks normal, so that you can use
833 them in a uniform way. Every variable whose name ends in @samp{-hook}
836 @cindex abnormal hook
837 A few hooks are @dfn{abnormal hooks}. Their names end in
838 @samp{-hooks} or @samp{-functions}, instead of @samp{-hook}. What
839 makes these hooks abnormal is the way its functions are
840 called---perhaps they are given arguments, or perhaps the values they
841 return are used in some way. For example,
842 @code{find-file-not-found-functions} is abnormal because as soon as
843 one hook function returns a non-@code{nil} value, the rest are not
844 called at all (@pxref{Visiting}). The documentation of each abnormal
845 hook variable explains how its functions are used.
848 You can set a hook variable with @code{setq} like any other Lisp
849 variable, but the recommended way to add a function to a hook (either
850 normal or abnormal) is to use @code{add-hook}, as shown by the
851 following examples. @xref{Hooks,,, elisp, The Emacs Lisp Reference
852 Manual}, for details.
854 Most major modes run one or more @dfn{mode hooks} as the last step
855 of initialization. Mode hooks are a convenient way to customize the
856 behavior of individual modes; they are always normal. For example,
857 here's how to set up a hook to turn on Auto Fill mode in Text mode and
858 other modes based on Text mode:
861 (add-hook 'text-mode-hook 'auto-fill-mode)
865 This works by calling @code{auto-fill-mode}, which enables the minor
866 mode when no argument is supplied (@pxref{Minor Modes}). Next,
867 suppose you don't want Auto Fill mode turned on in La@TeX{} mode,
868 which is one of the modes based on Text mode. You can do this with
869 the following additional line:
872 (add-hook 'latex-mode-hook (lambda () (auto-fill-mode -1)))
876 Here we have used the special macro @code{lambda} to construct an
877 anonymous function (@pxref{Lambda Expressions,,, elisp, The Emacs Lisp
878 Reference Manual}), which calls @code{auto-fill-mode} with an argument
879 of @code{-1} to disable the minor mode. Because La@TeX{} mode runs
880 @code{latex-mode-hook} after running @code{text-mode-hook}, the result
881 leaves Auto Fill mode disabled.
883 Here is a more complex example, showing how to use a hook to
884 customize the indentation of C code:
889 '((c-comment-only-line-offset . 4)
892 (c-cleanup-list . (scope-operator
898 (add-hook 'c-mode-common-hook
899 (lambda () (c-add-style "my-style" my-c-style t)))
904 @cindex program editing
905 Major mode hooks also apply to other major modes @dfn{derived} from
906 the original mode (@pxref{Derived Modes,,, elisp, The Emacs Lisp
907 Reference Manual}). For instance, HTML mode is derived from Text mode
908 (@pxref{HTML Mode}); when HTML mode is enabled, it runs
909 @code{text-mode-hook} before running @code{html-mode-hook}. This
910 provides a convenient way to use a single hook to affect several
911 related modes. In particular, if you want to apply a hook function to
912 any programming language mode, add it to @code{prog-mode-hook}; Prog
913 mode is a major mode that does little else than to let other major
914 modes inherit from it, exactly for this purpose.
916 It is best to design your hook functions so that the order in which
917 they are executed does not matter. Any dependence on the order is
918 asking for trouble. However, the order is predictable: the hook
919 functions are executed in the order they appear in the hook.
922 If you play with adding various different versions of a hook
923 function by calling @code{add-hook} over and over, remember that all
924 the versions you added will remain in the hook variable together. You
925 can clear out individual functions by calling @code{remove-hook}, or
926 do @code{(setq @var{hook-variable} nil)} to remove everything.
928 @cindex buffer-local hooks
929 If the hook variable is buffer-local, the buffer-local variable will
930 be used instead of the global variable. However, if the buffer-local
931 variable contains the element @code{t}, the global hook variable will
935 @subsection Local Variables
938 @item M-x make-local-variable @key{RET} @var{var} @key{RET}
939 Make variable @var{var} have a local value in the current buffer.
940 @item M-x kill-local-variable @key{RET} @var{var} @key{RET}
941 Make variable @var{var} use its global value in the current buffer.
942 @item M-x make-variable-buffer-local @key{RET} @var{var} @key{RET}
943 Mark variable @var{var} so that setting it will make it local to the
944 buffer that is current at that time.
947 @cindex local variables
948 Almost any variable can be made @dfn{local} to a specific Emacs
949 buffer. This means that its value in that buffer is independent of its
950 value in other buffers. A few variables are always local in every
951 buffer. Every other Emacs variable has a @dfn{global} value which is in
952 effect in all buffers that have not made the variable local.
954 @findex make-local-variable
955 @kbd{M-x make-local-variable} reads the name of a variable and makes
956 it local to the current buffer. Changing its value subsequently in
957 this buffer will not affect others, and changes in its global value
958 will not affect this buffer.
960 @findex make-variable-buffer-local
961 @cindex per-buffer variables
962 @kbd{M-x make-variable-buffer-local} marks a variable so it will
963 become local automatically whenever it is set. More precisely, once a
964 variable has been marked in this way, the usual ways of setting the
965 variable automatically do @code{make-local-variable} first. We call
966 such variables @dfn{per-buffer} variables. Many variables in Emacs
967 are normally per-buffer; the variable's document string tells you when
968 this is so. A per-buffer variable's global value is normally never
969 effective in any buffer, but it still has a meaning: it is the initial
970 value of the variable for each new buffer.
972 Major modes (@pxref{Major Modes}) always make variables local to the
973 buffer before setting the variables. This is why changing major modes
974 in one buffer has no effect on other buffers. Minor modes also work
975 by setting variables---normally, each minor mode has one controlling
976 variable which is non-@code{nil} when the mode is enabled
977 (@pxref{Minor Modes}). For many minor modes, the controlling variable
978 is per buffer, and thus always buffer-local. Otherwise, you can make
979 it local in a specific buffer like any other variable.
981 A few variables cannot be local to a buffer because they are always
982 local to each display instead (@pxref{Multiple Displays}). If you try to
983 make one of these variables buffer-local, you'll get an error message.
985 @findex kill-local-variable
986 @kbd{M-x kill-local-variable} makes a specified variable cease to be
987 local to the current buffer. The global value of the variable
988 henceforth is in effect in this buffer. Setting the major mode kills
989 all the local variables of the buffer except for a few variables
990 specially marked as @dfn{permanent locals}.
993 To set the global value of a variable, regardless of whether the
994 variable has a local value in the current buffer, you can use the Lisp
995 construct @code{setq-default}. This construct is used just like
996 @code{setq}, but it sets variables' global values instead of their local
997 values (if any). When the current buffer does have a local value, the
998 new global value may not be visible until you switch to another buffer.
1002 (setq-default fill-column 75)
1006 @code{setq-default} is the only way to set the global value of a variable
1007 that has been marked with @code{make-variable-buffer-local}.
1009 @findex default-value
1010 Lisp programs can use @code{default-value} to look at a variable's
1011 default value. This function takes a symbol as argument and returns its
1012 default value. The argument is evaluated; usually you must quote it
1013 explicitly. For example, here's how to obtain the default value of
1017 (default-value 'fill-column)
1020 @node File Variables
1021 @subsection Local Variables in Files
1022 @cindex local variables in files
1023 @cindex file local variables
1025 A file can specify local variable values to use when editing the
1026 file with Emacs. Visiting the file checks for local variable
1027 specifications; it automatically makes these variables local to the
1028 buffer, and sets them to the values specified in the file.
1031 * Specifying File Variables:: Specifying file local variables.
1032 * Safe File Variables:: Making sure file local variables are safe.
1035 @node Specifying File Variables
1036 @subsubsection Specifying File Variables
1038 There are two ways to specify file local variable values: in the first
1039 line, or with a local variables list. Here's how to specify them in the
1043 -*- mode: @var{modename}; @var{var}: @var{value}; @dots{} -*-
1047 You can specify any number of variable/value pairs in this way, each
1048 pair with a colon and semicolon. The special variable/value pair
1049 @code{mode: @var{modename};}, if present, specifies a major mode. The
1050 @var{value}s are used literally, and not evaluated.
1052 @findex add-file-local-variable-prop-line
1053 @findex delete-file-local-variable-prop-line
1054 @findex copy-dir-locals-to-file-locals-prop-line
1055 You can use @kbd{M-x add-file-local-variable-prop-line} instead of
1056 adding entries by hand. This command prompts for a variable and
1057 value, and adds them to the first line in the appropriate way.
1058 @kbd{M-x delete-file-local-variable-prop-line} prompts for a variable,
1059 and deletes its entry from the line. The command @kbd{M-x
1060 copy-dir-locals-to-file-locals-prop-line} copies the current
1061 directory-local variables to the first line (@pxref{Directory
1064 Here is an example first line that specifies Lisp mode and sets two
1065 variables with numeric values:
1068 ;; -*- mode: Lisp; fill-column: 75; comment-column: 50; -*-
1072 Aside from @code{mode}, other keywords that have special meanings as
1073 file variables are @code{coding}, @code{unibyte}, and @code{eval}.
1074 These are described below.
1076 @cindex shell scripts, and local file variables
1077 @cindex man pages, and local file variables
1078 In shell scripts, the first line is used to identify the script
1079 interpreter, so you cannot put any local variables there. To
1080 accommodate this, Emacs looks for local variable specifications in the
1081 @emph{second} line if the first line specifies an interpreter. The
1082 same is true for man pages which start with the magic string
1083 @samp{'\"} to specify a list of troff preprocessors (not all do,
1086 Apart from using a @samp{-*-} line, you can define file local
1087 variables using a @dfn{local variables list} near the end of the file.
1088 The start of the local variables list should be no more than 3000
1089 characters from the end of the file, and must be on the last page if
1090 the file is divided into pages.
1092 If a file has both a local variables list and a @samp{-*-} line,
1093 Emacs processes @emph{everything} in the @samp{-*-} line first, and
1094 @emph{everything} in the local variables list afterward. The exception
1095 to this is a major mode specification. Emacs applies this first,
1096 wherever it appears, since most major modes kill all local variables as
1097 part of their initialization.
1099 A local variables list starts with a line containing the string
1100 @samp{Local Variables:}, and ends with a line containing the string
1101 @samp{End:}. In between come the variable names and values, one set
1102 per line, like this:
1105 /* Local Variables: */
1107 /* comment-column: 0 */
1112 In this example, each line starts with the prefix @samp{/*} and ends
1113 with the suffix @samp{*/}. Emacs recognizes the prefix and suffix by
1114 finding them surrounding the magic string @samp{Local Variables:}, on
1115 the first line of the list; it then automatically discards them from
1116 the other lines of the list. The usual reason for using a prefix
1117 and/or suffix is to embed the local variables list in a comment, so it
1118 won't confuse other programs that the file is intended for. The
1119 example above is for the C programming language, where comments start
1120 with @samp{/*} and end with @samp{*/}.
1122 @findex add-file-local-variable
1123 @findex delete-file-local-variable
1124 @findex copy-dir-locals-to-file-locals
1125 Instead of typing in the local variables list directly, you can use
1126 the command @kbd{M-x add-file-local-variable}. This prompts for a
1127 variable and value, and adds them to the list, adding the @samp{Local
1128 Variables:} string and start and end markers as necessary. The
1129 command @kbd{M-x delete-file-local-variable} deletes a variable from
1130 the list. @kbd{M-x copy-dir-locals-to-file-locals} copies
1131 directory-local variables to the list (@pxref{Directory Variables}).
1133 As with the @samp{-*-} line, the variables in a local variables list
1134 are used literally, and are not evaluated first. If you want to split
1135 a long string value across multiple lines of the file, you can use
1136 backslash-newline, which is ignored in Lisp string constants; you
1137 should put the prefix and suffix on each line, even lines that start
1138 or end within the string, as they will be stripped off when processing
1139 the list. Here is an example:
1143 # compile-command: "cc foo.c -Dfoo=bar -Dhack=whatever \
1148 Some ``variable names'' have special meanings in a local variables
1153 @code{mode} enables the specified major mode.
1156 @code{eval} evaluates the specified Lisp expression (the value
1157 returned by that expression is ignored).
1160 @code{coding} specifies the coding system for character code
1161 conversion of this file. @xref{Coding Systems}.
1164 @code{unibyte} says to load or compile a file of Emacs Lisp in unibyte
1165 mode, if the value is @code{t}. @xref{Disabling Multibyte}.
1169 These four keywords are not really variables; setting them in any
1170 other context has no special meaning.
1172 Do not use the @code{mode} keyword for minor modes. To enable or
1173 disable a minor mode in a local variables list, use the @code{eval}
1174 keyword with a Lisp expression that runs the mode command
1175 (@pxref{Minor Modes}). For example, the following local variables
1176 list enables Eldoc mode (@pxref{Lisp Doc}) by calling
1177 @code{eldoc-mode} with no argument (calling it with an argument of 1
1178 would do the same), and disables Font Lock mode (@pxref{Font Lock}) by
1179 calling @code{font-lock-mode} with an argument of -1.
1183 ;; eval: (eldoc-mode)
1184 ;; eval: (font-lock-mode -1)
1189 Note, however, that it is often a mistake to specify minor modes this
1190 way. Minor modes represent individual user preferences, and it may be
1191 inappropriate to impose your preferences on another user who might
1192 edit the file. If you wish to automatically enable or disable a minor
1193 mode in a situation-dependent way, it is often better to do it in a
1194 major mode hook (@pxref{Hooks}).
1196 Use the command @kbd{M-x normal-mode} to reset the local variables
1197 and major mode of a buffer according to the file name and contents,
1198 including the local variables list if any. @xref{Choosing Modes}.
1200 @node Safe File Variables
1201 @subsubsection Safety of File Variables
1203 File-local variables can be dangerous; when you visit someone else's
1204 file, there's no telling what its local variables list could do to
1205 your Emacs. Improper values of the @code{eval} ``variable'', and
1206 other variables such as @code{load-path}, could execute Lisp code you
1207 didn't intend to run.
1209 Therefore, whenever Emacs encounters file local variable values that
1210 are not known to be safe, it displays the file's entire local
1211 variables list, and asks you for confirmation before setting them.
1212 You can type @kbd{y} or @key{SPC} to put the local variables list into
1213 effect, or @kbd{n} to ignore it. When Emacs is run in batch mode
1214 (@pxref{Initial Options}), it can't really ask you, so it assumes the
1217 Emacs normally recognizes certain variable/value pairs as safe.
1218 For instance, it is safe to give @code{comment-column} or
1219 @code{fill-column} any integer value. If a file specifies only
1220 known-safe variable/value pairs, Emacs does not ask for confirmation
1221 before setting them. Otherwise, you can tell Emacs to record all the
1222 variable/value pairs in this file as safe, by typing @kbd{!} at the
1223 confirmation prompt. When Emacs encounters these variable/value pairs
1224 subsequently, in the same file or others, it will assume they are
1227 @vindex safe-local-variable-values
1228 @cindex risky variable
1229 Some variables, such as @code{load-path}, are considered
1230 particularly @dfn{risky}: there is seldom any reason to specify them
1231 as local variables, and changing them can be dangerous. If a file
1232 contains only risky local variables, Emacs neither offers nor accepts
1233 @kbd{!} as input at the confirmation prompt. If some of the local
1234 variables in a file are risky, and some are only potentially unsafe, you
1235 can enter @kbd{!} at the prompt. It applies all the variables, but only
1236 marks the non-risky ones as safe for the future. If you really want to
1237 record safe values for risky variables, do it directly by customizing
1238 @samp{safe-local-variable-values} (@pxref{Easy Customization}).
1240 @vindex enable-local-variables
1241 The variable @code{enable-local-variables} allows you to change the
1242 way Emacs processes local variables. Its default value is @code{t},
1243 which specifies the behavior described above. If it is @code{nil},
1244 Emacs simply ignores all file local variables. @code{:safe} means use
1245 only the safe values and ignore the rest. Any other value says to
1246 query you about each file that has local variables, without trying to
1247 determine whether the values are known to be safe.
1249 @vindex enable-local-eval
1250 @vindex safe-local-eval-forms
1251 The variable @code{enable-local-eval} controls whether Emacs
1252 processes @code{eval} variables. The three possibilities for the
1253 variable's value are @code{t}, @code{nil}, and anything else, just as
1254 for @code{enable-local-variables}. The default is @code{maybe}, which
1255 is neither @code{t} nor @code{nil}, so normally Emacs does ask for
1256 confirmation about processing @code{eval} variables.
1258 As an exception, Emacs never asks for confirmation to evaluate any
1259 @code{eval} form if that form occurs within the variable
1260 @code{safe-local-eval-forms}.
1262 @node Directory Variables
1263 @subsection Per-Directory Local Variables
1264 @cindex local variables, for all files in a directory
1265 @cindex directory-local variables
1266 @cindex per-directory local variables
1268 Sometimes, you may wish to define the same set of local variables to
1269 all the files in a certain directory and its subdirectories, such as
1270 the directory tree of a large software project. This can be
1271 accomplished with @dfn{directory-local variables}.
1273 @cindex @file{.dir-locals.el} file
1274 The usual way to define directory-local variables is to put a file
1275 named @file{.dir-locals.el}@footnote{ On MS-DOS, the name of this file
1276 should be @file{_dir-locals.el}, due to limitations of the DOS
1277 filesystems. If the filesystem is limited to 8+3 file names, the name
1278 of the file will be truncated by the OS to @file{_dir-loc.el}. } in a
1279 directory. Whenever Emacs visits any file in that directory or any of
1280 its subdirectories, it will apply the directory-local variables
1281 specified in @file{.dir-locals.el}, as though they had been defined as
1282 file-local variables for that file (@pxref{File Variables}). Emacs
1283 searches for @file{.dir-locals.el} starting in the directory of the
1284 visited file, and moving up the directory tree. To avoid slowdown,
1285 this search is skipped for remote files.
1287 The @file{.dir-locals.el} file should hold a specially-constructed
1288 list, which maps major mode names (symbols) to alists
1289 (@pxref{Association Lists,,, elisp, The Emacs Lisp Reference Manual}).
1290 Each alist entry consists of a variable name and the directory-local
1291 value to assign to that variable, when the specified major mode is
1292 enabled. Instead of a mode name, you can specify @samp{nil}, which
1293 means that the alist applies to any mode; or you can specify a
1294 subdirectory name (a string), in which case the alist applies to all
1295 files in that subdirectory.
1297 Here's an example of a @file{.dir-locals.el} file:
1300 ((nil . ((indent-tabs-mode . t)
1301 (fill-column . 80)))
1302 (c-mode . ((c-file-style . "BSD")))
1305 . ((nil . ((change-log-default-name
1306 . "ChangeLog.local"))))))
1310 This sets @samp{indent-tabs-mode} and @code{fill-column} for any file
1311 in the directory tree, and the indentation style for any C source
1312 file. The special @code{subdirs} element is not a variable, but a
1313 special keyword which indicates that the C mode settings are only to
1314 be applied in the current directory, not in any subdirectories.
1315 Finally, it specifies a different @file{ChangeLog} file name for any
1316 file in the @file{src/imported} subdirectory.
1318 @findex add-dir-local-variable
1319 @findex delete-dir-local-variable
1320 @findex copy-file-locals-to-dir-locals
1321 Instead of editing the @file{.dir-locals.el} file by hand, you can
1322 use the command @kbd{M-x add-dir-local-variable}. This prompts for a
1323 mode or subdirectory name, and for variable and value, and adds the
1324 entry defining the directory-local variable. @kbd{M-x
1325 delete-dir-local-variable} deletes an entry. @kbd{M-x
1326 copy-file-locals-to-dir-locals} copies the file-local variables in the
1327 current file into @file{.dir-locals.el}.
1329 @findex dir-locals-set-class-variables
1330 @findex dir-locals-set-directory-class
1331 Another method of specifying directory-local variables is to define
1332 a group of variables/value pairs in a @dfn{directory class}, using the
1333 @code{dir-locals-set-class-variables} function; then, tell Emacs which
1334 directories correspond to the class by using the
1335 @code{dir-locals-set-directory-class} function. These function calls
1336 normally go in your initialization file (@pxref{Init File}). This
1337 method is useful when you can't put @file{.dir-locals.el} in a
1338 directory for some reason. For example, you could apply settings to
1339 an unwritable directory this way:
1342 (dir-locals-set-class-variables 'unwritable-directory
1343 '((nil . ((some-useful-setting . value)))))
1345 (dir-locals-set-directory-class
1346 "/usr/include/" 'unwritable-directory)
1349 If a variable has both a directory-local and file-local value
1350 specified, the file-local value takes effect. Unsafe directory-local
1351 variables are handled in the same way as unsafe file-local variables
1352 (@pxref{Safe File Variables}).
1354 Directory-local variables also take effect in certain buffers that
1355 do not visit a file directly but perform work within a directory, such
1356 as Dired buffers (@pxref{Dired}).
1359 @section Customizing Key Bindings
1360 @cindex key bindings
1362 This section describes @dfn{key bindings}, which map keys to
1363 commands, and @dfn{keymaps}, which record key bindings. It also
1364 explains how to customize key bindings, which is done by editing your
1365 init file (@pxref{Init Rebinding}).
1368 * Keymaps:: Generalities. The global keymap.
1369 * Prefix Keymaps:: Keymaps for prefix keys.
1370 * Local Keymaps:: Major and minor modes have their own keymaps.
1371 * Minibuffer Maps:: The minibuffer uses its own local keymaps.
1372 * Rebinding:: How to redefine one key's meaning conveniently.
1373 * Init Rebinding:: Rebinding keys with your initialization file.
1374 * Modifier Keys:: Using modifier keys in key bindings.
1375 * Function Keys:: Rebinding terminal function keys.
1376 * Named ASCII Chars:: Distinguishing @key{TAB} from @kbd{C-i}, and so on.
1377 * Mouse Buttons:: Rebinding mouse buttons in Emacs.
1378 * Disabling:: Disabling a command means confirmation is required
1379 before it can be executed. This is done to protect
1380 beginners from surprises.
1387 As described in @ref{Commands}, each Emacs command is a Lisp
1388 function whose definition provides for interactive use. Like every
1389 Lisp function, a command has a function name, which usually consists
1390 of lower-case letters and hyphens.
1392 A @dfn{key sequence} (@dfn{key}, for short) is a sequence of
1393 @dfn{input events} that have a meaning as a unit. Input events
1394 include characters, function keys and mouse buttons---all the inputs
1395 that you can send to the computer. A key sequence gets its meaning
1396 from its @dfn{binding}, which says what command it runs.
1398 The bindings between key sequences and command functions are
1399 recorded in data structures called @dfn{keymaps}. Emacs has many of
1400 these, each used on particular occasions.
1402 @cindex global keymap
1403 The @dfn{global} keymap is the most important keymap because it is
1404 always in effect. The global keymap defines keys for Fundamental mode
1405 (@pxref{Major Modes}); most of these definitions are common to most or
1406 all major modes. Each major or minor mode can have its own keymap
1407 which overrides the global definitions of some keys.
1409 For example, a self-inserting character such as @kbd{g} is
1410 self-inserting because the global keymap binds it to the command
1411 @code{self-insert-command}. The standard Emacs editing characters
1412 such as @kbd{C-a} also get their standard meanings from the global
1413 keymap. Commands to rebind keys, such as @kbd{M-x global-set-key},
1414 work by storing the new binding in the proper place in the global map
1415 (@pxref{Rebinding}).
1417 @cindex function key
1418 Most modern keyboards have function keys as well as character keys.
1419 Function keys send input events just as character keys do, and keymaps
1420 can have bindings for them. Key sequences can mix function keys and
1421 characters. For example, if your keyboard has a @key{Home} function
1422 key, Emacs can recognize key sequences like @kbd{C-x @key{Home}}. You
1423 can even mix mouse events with keyboard events, such as
1424 @kbd{S-down-mouse-1}.
1426 On text terminals, typing a function key actually sends the computer
1427 a sequence of characters; the precise details of the sequence depends
1428 on the function key and on the terminal type. (Often the sequence
1429 starts with @kbd{@key{ESC} [}.) If Emacs understands your terminal
1430 type properly, it automatically handles such sequences as single input
1433 @node Prefix Keymaps
1434 @subsection Prefix Keymaps
1436 Internally, Emacs records only single events in each keymap.
1437 Interpreting a key sequence of multiple events involves a chain of
1438 keymaps: the first keymap gives a definition for the first event,
1439 which is another keymap, which is used to look up the second event in
1440 the sequence, and so on. Thus, a prefix key such as @kbd{C-x} or
1441 @key{ESC} has its own keymap, which holds the definition for the event
1442 that immediately follows that prefix.
1444 The definition of a prefix key is usually the keymap to use for
1445 looking up the following event. The definition can also be a Lisp
1446 symbol whose function definition is the following keymap; the effect is
1447 the same, but it provides a command name for the prefix key that can be
1448 used as a description of what the prefix key is for. Thus, the binding
1449 of @kbd{C-x} is the symbol @code{Control-X-prefix}, whose function
1450 definition is the keymap for @kbd{C-x} commands. The definitions of
1451 @kbd{C-c}, @kbd{C-x}, @kbd{C-h} and @key{ESC} as prefix keys appear in
1452 the global map, so these prefix keys are always available.
1454 Aside from ordinary prefix keys, there is a fictitious ``prefix key''
1455 which represents the menu bar; see @ref{Menu Bar,,,elisp, The Emacs Lisp
1456 Reference Manual}, for special information about menu bar key bindings.
1457 Mouse button events that invoke pop-up menus are also prefix keys; see
1458 @ref{Menu Keymaps,,,elisp, The Emacs Lisp Reference Manual}, for more
1461 Some prefix keymaps are stored in variables with names:
1466 @code{ctl-x-map} is the variable name for the map used for characters that
1470 @code{help-map} is for characters that follow @kbd{C-h}.
1473 @code{esc-map} is for characters that follow @key{ESC}. Thus, all Meta
1474 characters are actually defined by this map.
1477 @code{ctl-x-4-map} is for characters that follow @kbd{C-x 4}.
1479 @vindex mode-specific-map
1480 @code{mode-specific-map} is for characters that follow @kbd{C-c}.
1484 @subsection Local Keymaps
1486 @cindex local keymap
1487 @cindex minor mode keymap
1488 So far, we have explained the ins and outs of the global map. Major
1489 modes customize Emacs by providing their own key bindings in
1490 @dfn{local keymaps}. For example, C mode overrides @key{TAB} to make
1491 it indent the current line for C code. Minor modes can also have
1492 local keymaps; whenever a minor mode is in effect, the definitions in
1493 its keymap override both the major mode's local keymap and the global
1494 keymap. In addition, portions of text in the buffer can specify their
1495 own keymaps, which override all other keymaps.
1497 A local keymap can redefine a key as a prefix key by defining it as
1498 a prefix keymap. If the key is also defined globally as a prefix, its
1499 local and global definitions (both keymaps) effectively combine: both
1500 definitions are used to look up the event that follows the prefix key.
1501 For example, if a local keymap defines @kbd{C-c} as a prefix keymap,
1502 and that keymap defines @kbd{C-z} as a command, this provides a local
1503 meaning for @kbd{C-c C-z}. This does not affect other sequences that
1504 start with @kbd{C-c}; if those sequences don't have their own local
1505 bindings, their global bindings remain in effect.
1507 Another way to think of this is that Emacs handles a multi-event key
1508 sequence by looking in several keymaps, one by one, for a binding of the
1509 whole key sequence. First it checks the minor mode keymaps for minor
1510 modes that are enabled, then it checks the major mode's keymap, and then
1511 it checks the global keymap. This is not precisely how key lookup
1512 works, but it's good enough for understanding the results in ordinary
1515 @node Minibuffer Maps
1516 @subsection Minibuffer Keymaps
1518 @cindex minibuffer keymaps
1519 @vindex minibuffer-local-map
1520 @vindex minibuffer-local-ns-map
1521 @vindex minibuffer-local-completion-map
1522 @vindex minibuffer-local-must-match-map
1523 @vindex minibuffer-local-filename-completion-map
1524 @vindex minibuffer-local-filename-must-match-map
1525 The minibuffer has its own set of local keymaps; they contain various
1526 completion and exit commands.
1530 @code{minibuffer-local-map} is used for ordinary input (no completion).
1532 @code{minibuffer-local-ns-map} is similar, except that @key{SPC} exits
1533 just like @key{RET}.
1535 @code{minibuffer-local-completion-map} is for permissive completion.
1537 @code{minibuffer-local-must-match-map} is for strict completion and
1538 for cautious completion.
1540 @code{minibuffer-local-filename-completion-map} and
1541 @code{minibuffer-local-filename-must-match-map} are like the two
1542 previous ones, but they are specifically for file name completion.
1543 They do not bind @key{SPC}.
1547 @subsection Changing Key Bindings Interactively
1548 @cindex key rebinding, this session
1549 @cindex redefining keys, this session
1550 @cindex binding keys
1552 The way to redefine an Emacs key is to change its entry in a keymap.
1553 You can change the global keymap, in which case the change is
1554 effective in all major modes (except those that have their own
1555 overriding local bindings for the same key). Or you can change a
1556 local keymap, which affects all buffers using the same major mode.
1558 In this section, we describe how to rebind keys for the present
1559 Emacs session. @xref{Init Rebinding}, for a description of how to
1560 make key rebindings affect future Emacs sessions.
1562 @findex global-set-key
1563 @findex local-set-key
1564 @findex global-unset-key
1565 @findex local-unset-key
1567 @item M-x global-set-key @key{RET} @var{key} @var{cmd} @key{RET}
1568 Define @var{key} globally to run @var{cmd}.
1569 @item M-x local-set-key @key{RET} @var{key} @var{cmd} @key{RET}
1570 Define @var{key} locally (in the major mode now in effect) to run
1572 @item M-x global-unset-key @key{RET} @var{key}
1573 Make @var{key} undefined in the global map.
1574 @item M-x local-unset-key @key{RET} @var{key}
1575 Make @var{key} undefined locally (in the major mode now in effect).
1578 For example, the following binds @kbd{C-z} to the @code{shell}
1579 command (@pxref{Interactive Shell}), replacing the normal global
1580 definition of @kbd{C-z}:
1583 M-x global-set-key @key{RET} C-z shell @key{RET}
1587 The @code{global-set-key} command reads the command name after the
1588 key. After you press the key, a message like this appears so that you
1589 can confirm that you are binding the key you want:
1592 Set key C-z to command:
1595 You can redefine function keys and mouse events in the same way; just
1596 type the function key or click the mouse when it's time to specify the
1599 You can rebind a key that contains more than one event in the same
1600 way. Emacs keeps reading the key to rebind until it is a complete key
1601 (that is, not a prefix key). Thus, if you type @kbd{C-f} for
1602 @var{key}, that's the end; it enters the minibuffer immediately to
1603 read @var{cmd}. But if you type @kbd{C-x}, since that's a prefix, it
1604 reads another character; if that is @kbd{4}, another prefix character,
1605 it reads one more character, and so on. For example,
1608 M-x global-set-key @key{RET} C-x 4 $ spell-other-window @key{RET}
1612 redefines @kbd{C-x 4 $} to run the (fictitious) command
1613 @code{spell-other-window}.
1615 You can remove the global definition of a key with
1616 @code{global-unset-key}. This makes the key @dfn{undefined}; if you
1617 type it, Emacs will just beep. Similarly, @code{local-unset-key} makes
1618 a key undefined in the current major mode keymap, which makes the global
1619 definition (or lack of one) come back into effect in that major mode.
1621 If you have redefined (or undefined) a key and you subsequently wish
1622 to retract the change, undefining the key will not do the job---you need
1623 to redefine the key with its standard definition. To find the name of
1624 the standard definition of a key, go to a Fundamental mode buffer in a
1625 fresh Emacs and use @kbd{C-h c}. The documentation of keys in this
1626 manual also lists their command names.
1628 If you want to prevent yourself from invoking a command by mistake, it
1629 is better to disable the command than to undefine the key. A disabled
1630 command is less work to invoke when you really want to.
1633 @node Init Rebinding
1634 @subsection Rebinding Keys in Your Init File
1635 @cindex rebinding major mode keys
1636 @c This node is referenced in the tutorial. When renaming or deleting
1637 @c it, the tutorial needs to be adjusted. (TUTORIAL.de)
1639 If you have a set of key bindings that you like to use all the time,
1640 you can specify them in your initialization file by writing Lisp code.
1641 @xref{Init File}, for a description of the initialization file.
1644 There are several ways to write a key binding using Lisp. The
1645 simplest is to use the @code{kbd} macro, which converts a textual
1646 representation of a key sequence---similar to how we have written key
1647 sequences in this manual---into a form that can be passed as an
1648 argument to @code{global-set-key}. For example, here's how to bind
1649 @kbd{C-z} to the @code{shell} command (@pxref{Interactive Shell}):
1652 (global-set-key (kbd "C-z") 'shell)
1656 The single-quote before the command name, @code{shell}, marks it as a
1657 constant symbol rather than a variable. If you omit the quote, Emacs
1658 would try to evaluate @code{shell} as a variable. This probably
1659 causes an error; it certainly isn't what you want.
1661 Here are some additional examples, including binding function keys
1665 (global-set-key (kbd "C-c y") 'clipboard-yank)
1666 (global-set-key (kbd "C-M-q") 'query-replace)
1667 (global-set-key (kbd "<f5>") 'flyspell-mode)
1668 (global-set-key (kbd "C-<f5>") 'linum-mode)
1669 (global-set-key (kbd "C-<right>") 'forward-sentence)
1670 (global-set-key (kbd "<mouse-2>") 'mouse-save-then-kill)
1673 Instead of using the @code{kbd} macro, you can use a Lisp string or
1674 vector to specify the key sequence. Using a string is simpler, but
1675 only works for @acronym{ASCII} characters and Meta-modified
1676 @acronym{ASCII} characters. For example, here's how to bind @kbd{C-x
1677 M-l} to @code{make-symbolic-link} (@pxref{Misc File Ops}):
1680 (global-set-key "\C-x\M-l" 'make-symbolic-link)
1683 To put @key{TAB}, @key{RET}, @key{ESC}, or @key{DEL} in the string,
1684 use the Emacs Lisp escape sequences @samp{\t}, @samp{\r}, @samp{\e},
1685 and @samp{\d} respectively. Here is an example which binds @kbd{C-x
1686 @key{TAB}} to @code{indent-rigidly} (@pxref{Indentation}):
1689 (global-set-key "\C-x\t" 'indent-rigidly)
1692 When the key sequence includes function keys or mouse button events,
1693 or non-@acronym{ASCII} characters such as @code{C-=} or @code{H-a},
1694 you can use a vector to specify the key sequence. Each element in the
1695 vector stands for an input event; the elements are separated by spaces
1696 and surrounded by a pair of square brackets. If a vector element is a
1697 character, write it as a Lisp character constant: @samp{?} followed by
1698 the character as it would appear in a string. Function keys are
1699 represented by symbols (@pxref{Function Keys}); simply write the
1700 symbol's name, with no other delimiters or punctuation. Here are some
1704 (global-set-key [?\C-=] 'make-symbolic-link)
1705 (global-set-key [?\M-\C-=] 'make-symbolic-link)
1706 (global-set-key [?\H-a] 'make-symbolic-link)
1707 (global-set-key [f7] 'make-symbolic-link)
1708 (global-set-key [C-mouse-1] 'make-symbolic-link)
1712 You can use a vector for the simple cases too:
1715 (global-set-key [?\C-z ?\M-l] 'make-symbolic-link)
1718 Language and coding systems may cause problems with key bindings for
1719 non-@acronym{ASCII} characters. @xref{Init Non-ASCII}.
1721 As described in @ref{Local Keymaps}, major modes and minor modes can
1722 define local keymaps. These keymaps are constructed when the mode is
1723 used for the first time in a session. If you wish to change one of
1724 these keymaps, you must use the @dfn{mode hook} (@pxref{Hooks}).
1727 For example, Texinfo mode runs the hook @code{texinfo-mode-hook}.
1728 Here's how you can use the hook to add local bindings for @kbd{C-c n}
1729 and @kbd{C-c p} in Texinfo mode:
1732 (add-hook 'texinfo-mode-hook
1734 (define-key texinfo-mode-map "\C-cp"
1735 'backward-paragraph)
1736 (define-key texinfo-mode-map "\C-cn"
1737 'forward-paragraph)))
1741 @subsection Modifier Keys
1742 @cindex modifier keys
1744 The default key bindings in Emacs are set up so that modified
1745 alphabetical characters are case-insensitive. In other words,
1746 @kbd{C-A} does the same thing as @kbd{C-a}, and @kbd{M-A} does the
1747 same thing as @kbd{M-a}. This concerns only alphabetical characters,
1748 and does not apply to ``shifted'' versions of other keys; for
1749 instance, @kbd{C-@@} is not the same as @kbd{C-2}.
1751 A @key{Control}-modified alphabetical character is always considered
1752 case-insensitive: Emacs always treats @kbd{C-A} as @kbd{C-a},
1753 @kbd{C-B} as @kbd{C-b}, and so forth. The reason for this is
1756 For all other modifiers, you can make the modified alphabetical
1757 characters case-sensitive when you customize Emacs. For instance, you
1758 could make @kbd{M-a} and @kbd{M-A} run different commands.
1760 Although only the @key{Control} and @key{Meta} modifier keys are
1761 commonly used, Emacs supports three other modifier keys. These are
1762 called @key{Super}, @key{Hyper} and @key{Alt}. Few terminals provide
1763 ways to use these modifiers; the key labeled @key{Alt} on most
1764 keyboards usually issues the @key{Meta} modifier, not @key{Alt}. The
1765 standard key bindings in Emacs do not include any characters with
1766 these modifiers. However, you can customize Emacs to assign meanings
1767 to them. The modifier bits are labeled as @samp{s-}, @samp{H-} and
1768 @samp{A-} respectively.
1770 Even if your keyboard lacks these additional modifier keys, you can
1771 enter it using @kbd{C-x @@}: @kbd{C-x @@ h} adds the ``hyper'' flag to
1772 the next character, @kbd{C-x @@ s} adds the ``super'' flag, and
1773 @kbd{C-x @@ a} adds the ``alt'' flag. For instance, @kbd{C-x @@ h
1774 C-a} is a way to enter @kbd{Hyper-Control-a}. (Unfortunately, there
1775 is no way to add two modifiers by using @kbd{C-x @@} twice for the
1776 same character, because the first one goes to work on the @kbd{C-x}.)
1779 @subsection Rebinding Function Keys
1781 Key sequences can contain function keys as well as ordinary
1782 characters. Just as Lisp characters (actually integers) represent
1783 keyboard characters, Lisp symbols represent function keys. If the
1784 function key has a word as its label, then that word is also the name of
1785 the corresponding Lisp symbol. Here are the conventional Lisp names for
1786 common function keys:
1789 @item @code{left}, @code{up}, @code{right}, @code{down}
1792 @item @code{begin}, @code{end}, @code{home}, @code{next}, @code{prior}
1793 Other cursor repositioning keys.
1795 @item @code{select}, @code{print}, @code{execute}, @code{backtab}
1796 @itemx @code{insert}, @code{undo}, @code{redo}, @code{clearline}
1797 @itemx @code{insertline}, @code{deleteline}, @code{insertchar}, @code{deletechar}
1798 Miscellaneous function keys.
1800 @item @code{f1}, @code{f2}, @dots{} @code{f35}
1801 Numbered function keys (across the top of the keyboard).
1803 @item @code{kp-add}, @code{kp-subtract}, @code{kp-multiply}, @code{kp-divide}
1804 @itemx @code{kp-backtab}, @code{kp-space}, @code{kp-tab}, @code{kp-enter}
1805 @itemx @code{kp-separator}, @code{kp-decimal}, @code{kp-equal}
1806 Keypad keys (to the right of the regular keyboard), with names or punctuation.
1808 @item @code{kp-0}, @code{kp-1}, @dots{} @code{kp-9}
1809 Keypad keys with digits.
1811 @item @code{kp-f1}, @code{kp-f2}, @code{kp-f3}, @code{kp-f4}
1815 These names are conventional, but some systems (especially when using
1816 X) may use different names. To make certain what symbol is used for a
1817 given function key on your terminal, type @kbd{C-h c} followed by that
1820 @xref{Init Rebinding}, for examples of binding function keys.
1823 Many keyboards have a ``numeric keypad'' on the right hand side.
1824 The numeric keys in the keypad double up as cursor motion keys,
1825 toggled by a key labeled @samp{Num Lock}. By default, Emacs
1826 translates these keys to the corresponding keys in the main keyboard.
1827 For example, when @samp{Num Lock} is on, the key labeled @samp{8} on
1828 the numeric keypad produces @code{kp-8}, which is translated to
1829 @kbd{8}; when @samp{Num Lock} is off, the same key produces
1830 @code{kp-up}, which is translated to @key{UP}. If you rebind a key
1831 such as @kbd{8} or @key{UP}, it affects the equivalent keypad key too.
1832 However, if you rebind a @samp{kp-} key directly, that won't affect
1833 its non-keypad equivalent. Note that the modified keys are not
1834 translated: for instance, if you hold down the @key{META} key while
1835 pressing the @samp{8} key on the numeric keypad, that generates
1838 Emacs provides a convenient method for binding the numeric keypad
1839 keys, using the variables @code{keypad-setup},
1840 @code{keypad-numlock-setup}, @code{keypad-shifted-setup}, and
1841 @code{keypad-numlock-shifted-setup}. These can be found in the
1842 @samp{keyboard} customization group (@pxref{Easy Customization}). You
1843 can rebind the keys to perform other tasks, such as issuing numeric
1846 @node Named ASCII Chars
1847 @subsection Named @acronym{ASCII} Control Characters
1849 @key{TAB}, @key{RET}, @key{BS}, @key{LFD}, @key{ESC} and @key{DEL}
1850 started out as names for certain @acronym{ASCII} control characters,
1851 used so often that they have special keys of their own. For instance,
1852 @key{TAB} was another name for @kbd{C-i}. Later, users found it
1853 convenient to distinguish in Emacs between these keys and the ``same''
1854 control characters typed with the @key{CTRL} key. Therefore, on most
1855 modern terminals, they are no longer the same: @key{TAB} is different
1858 Emacs can distinguish these two kinds of input if the keyboard does.
1859 It treats the ``special'' keys as function keys named @code{tab},
1860 @code{return}, @code{backspace}, @code{linefeed}, @code{escape}, and
1861 @code{delete}. These function keys translate automatically into the
1862 corresponding @acronym{ASCII} characters @emph{if} they have no
1863 bindings of their own. As a result, neither users nor Lisp programs
1864 need to pay attention to the distinction unless they care to.
1866 If you do not want to distinguish between (for example) @key{TAB} and
1867 @kbd{C-i}, make just one binding, for the @acronym{ASCII} character @key{TAB}
1868 (octal code 011). If you do want to distinguish, make one binding for
1869 this @acronym{ASCII} character, and another for the ``function key'' @code{tab}.
1871 With an ordinary @acronym{ASCII} terminal, there is no way to distinguish
1872 between @key{TAB} and @kbd{C-i} (and likewise for other such pairs),
1873 because the terminal sends the same character in both cases.
1876 @subsection Rebinding Mouse Buttons
1877 @cindex mouse button events
1878 @cindex rebinding mouse buttons
1879 @cindex click events
1882 @cindex button down events
1884 Emacs uses Lisp symbols to designate mouse buttons, too. The ordinary
1885 mouse events in Emacs are @dfn{click} events; these happen when you
1886 press a button and release it without moving the mouse. You can also
1887 get @dfn{drag} events, when you move the mouse while holding the button
1888 down. Drag events happen when you finally let go of the button.
1890 The symbols for basic click events are @code{mouse-1} for the leftmost
1891 button, @code{mouse-2} for the next, and so on. Here is how you can
1892 redefine the second mouse button to split the current window:
1895 (global-set-key [mouse-2] 'split-window-below)
1898 The symbols for drag events are similar, but have the prefix
1899 @samp{drag-} before the word @samp{mouse}. For example, dragging the
1900 first button generates a @code{drag-mouse-1} event.
1902 You can also define bindings for events that occur when a mouse button
1903 is pressed down. These events start with @samp{down-} instead of
1904 @samp{drag-}. Such events are generated only if they have key bindings.
1905 When you get a button-down event, a corresponding click or drag event
1908 @cindex double clicks
1909 @cindex triple clicks
1910 If you wish, you can distinguish single, double, and triple clicks. A
1911 double click means clicking a mouse button twice in approximately the
1912 same place. The first click generates an ordinary click event. The
1913 second click, if it comes soon enough, generates a double-click event
1914 instead. The event type for a double-click event starts with
1915 @samp{double-}: for example, @code{double-mouse-3}.
1917 This means that you can give a special meaning to the second click at
1918 the same place, but it must act on the assumption that the ordinary
1919 single click definition has run when the first click was received.
1921 This constrains what you can do with double clicks, but user interface
1922 designers say that this constraint ought to be followed in any case. A
1923 double click should do something similar to the single click, only
1924 ``more so''. The command for the double-click event should perform the
1925 extra work for the double click.
1927 If a double-click event has no binding, it changes to the
1928 corresponding single-click event. Thus, if you don't define a
1929 particular double click specially, it executes the single-click command
1932 Emacs also supports triple-click events whose names start with
1933 @samp{triple-}. Emacs does not distinguish quadruple clicks as event
1934 types; clicks beyond the third generate additional triple-click events.
1935 However, the full number of clicks is recorded in the event list, so
1936 if you know Emacs Lisp you can distinguish if you really want to
1937 (@pxref{Click Events,,, elisp, The Emacs Lisp Reference Manual}).
1938 We don't recommend distinct meanings for more than three clicks, but
1939 sometimes it is useful for subsequent clicks to cycle through the same
1940 set of three meanings, so that four clicks are equivalent to one
1941 click, five are equivalent to two, and six are equivalent to three.
1943 Emacs also records multiple presses in drag and button-down events.
1944 For example, when you press a button twice, then move the mouse while
1945 holding the button, Emacs gets a @samp{double-drag-} event. And at the
1946 moment when you press it down for the second time, Emacs gets a
1947 @samp{double-down-} event (which is ignored, like all button-down
1948 events, if it has no binding).
1950 @vindex double-click-time
1951 The variable @code{double-click-time} specifies how much time can
1952 elapse between clicks and still allow them to be grouped as a multiple
1953 click. Its value is in units of milliseconds. If the value is
1954 @code{nil}, double clicks are not detected at all. If the value is
1955 @code{t}, then there is no time limit. The default is 500.
1957 @vindex double-click-fuzz
1958 The variable @code{double-click-fuzz} specifies how much the mouse
1959 can move between clicks and still allow them to be grouped as a multiple
1960 click. Its value is in units of pixels on windowed displays and in
1961 units of 1/8 of a character cell on text-mode terminals; the default is
1964 The symbols for mouse events also indicate the status of the modifier
1965 keys, with the usual prefixes @samp{C-}, @samp{M-}, @samp{H-},
1966 @samp{s-}, @samp{A-} and @samp{S-}. These always precede @samp{double-}
1967 or @samp{triple-}, which always precede @samp{drag-} or @samp{down-}.
1969 A frame includes areas that don't show text from the buffer, such as
1970 the mode line and the scroll bar. You can tell whether a mouse button
1971 comes from a special area of the screen by means of dummy ``prefix
1972 keys''. For example, if you click the mouse in the mode line, you get
1973 the prefix key @code{mode-line} before the ordinary mouse-button symbol.
1974 Thus, here is how to define the command for clicking the first button in
1975 a mode line to run @code{scroll-up-command}:
1978 (global-set-key [mode-line mouse-1] 'scroll-up-command)
1981 Here is the complete list of these dummy prefix keys and their
1986 The mouse was in the mode line of a window.
1988 The mouse was in the vertical line separating side-by-side windows. (If
1989 you use scroll bars, they appear in place of these vertical lines.)
1990 @item vertical-scroll-bar
1991 The mouse was in a vertical scroll bar. (This is the only kind of
1992 scroll bar Emacs currently supports.)
1994 The mouse was in the menu bar.
1996 The mouse was in a header line.
1998 @item horizontal-scroll-bar
1999 The mouse was in a horizontal scroll bar. Horizontal scroll bars do
2000 horizontal scrolling, and people don't use them often.
2004 You can put more than one mouse button in a key sequence, but it isn't
2008 @subsection Disabling Commands
2009 @cindex disabled command
2011 Disabling a command means that invoking it interactively asks for
2012 confirmation from the user. The purpose of disabling a command is to
2013 prevent users from executing it by accident; we do this for commands
2014 that might be confusing to the uninitiated.
2016 Attempting to invoke a disabled command interactively in Emacs
2017 displays a window containing the command's name, its documentation,
2018 and some instructions on what to do immediately; then Emacs asks for
2019 input saying whether to execute the command as requested, enable it
2020 and execute it, or cancel. If you decide to enable the command, you
2021 must then answer another question---whether to do this permanently, or
2022 just for the current session. (Enabling permanently works by
2023 automatically editing your initialization file.) You can also type
2024 @kbd{!} to enable @emph{all} commands, for the current session only.
2026 The direct mechanism for disabling a command is to put a
2027 non-@code{nil} @code{disabled} property on the Lisp symbol for the
2028 command. Here is the Lisp program to do this:
2031 (put 'delete-region 'disabled t)
2034 If the value of the @code{disabled} property is a string, that string
2035 is included in the message displayed when the command is used:
2038 (put 'delete-region 'disabled
2039 "It's better to use `kill-region' instead.\n")
2042 @findex disable-command
2043 @findex enable-command
2044 You can make a command disabled either by editing the initialization
2045 file directly, or with the command @kbd{M-x disable-command}, which
2046 edits the initialization file for you. Likewise, @kbd{M-x
2047 enable-command} edits the initialization file to enable a command
2048 permanently. @xref{Init File}.
2050 If Emacs was invoked with the @option{-q} or @option{--no-init-file}
2051 options (@pxref{Initial Options}), it will not edit your
2052 initialization file. Doing so could lose information because Emacs
2053 has not read your initialization file.
2055 Whether a command is disabled is independent of what key is used to
2056 invoke it; disabling also applies if the command is invoked using
2057 @kbd{M-x}. However, disabling a command has no effect on calling it
2058 as a function from Lisp programs.
2061 @section The Emacs Initialization File
2064 @cindex ~/.emacs file
2065 @cindex Emacs initialization file
2066 @cindex key rebinding, permanent
2067 @cindex rebinding keys, permanently
2068 @cindex startup (init file)
2070 When Emacs is started, it normally tries to load a Lisp program from
2071 an @dfn{initialization file}, or @dfn{init file} for short. This
2072 file, if it exists, specifies how to initialize Emacs for you. Emacs
2073 looks for your init file using the filenames @file{~/.emacs},
2074 @file{~/.emacs.el}, or @file{~/.emacs.d/init.el}; you can choose to
2075 use any one of these three names (@pxref{Find Init}). Here, @file{~/}
2076 stands for your home directory.
2078 You can use the command line switch @samp{-q} to prevent loading
2079 your init file, and @samp{-u} (or @samp{--user}) to specify a
2080 different user's init file (@pxref{Initial Options}).
2082 @cindex @file{default.el}, the default init file
2083 There can also be a @dfn{default init file}, which is the library
2084 named @file{default.el}, found via the standard search path for
2085 libraries. The Emacs distribution contains no such library; your site
2086 may create one for local customizations. If this library exists, it is
2087 loaded whenever you start Emacs (except when you specify @samp{-q}).
2088 But your init file, if any, is loaded first; if it sets
2089 @code{inhibit-default-init} non-@code{nil}, then @file{default} is not
2092 @cindex site init file
2093 @cindex @file{site-start.el}, the site startup file
2094 Your site may also have a @dfn{site startup file}; this is named
2095 @file{site-start.el}, if it exists. Like @file{default.el}, Emacs
2096 finds this file via the standard search path for Lisp libraries.
2097 Emacs loads this library before it loads your init file. To inhibit
2098 loading of this library, use the option @samp{--no-site-file}.
2099 @xref{Initial Options}. We recommend against using
2100 @file{site-start.el} for changes that some users may not like. It is
2101 better to put them in @file{default.el}, so that users can more easily
2104 You can place @file{default.el} and @file{site-start.el} in any of
2105 the directories which Emacs searches for Lisp libraries. The variable
2106 @code{load-path} (@pxref{Lisp Libraries}) specifies these directories.
2107 Many sites put these files in the @file{site-lisp} subdirectory of the
2108 Emacs installation directory, typically
2109 @file{/usr/local/share/emacs/site-lisp}.
2111 Byte-compiling your init file is not recommended (@pxref{Byte
2112 Compilation,, Byte Compilation, elisp, the Emacs Lisp Reference
2113 Manual}). It generally does not speed up startup very much, and often
2114 leads to problems when you forget to recompile the file. A better
2115 solution is to use the Emacs server to reduce the number of times you
2116 have to start Emacs (@pxref{Emacs Server}). If your init file defines
2117 many functions, consider moving them to a separate (byte-compiled)
2118 file that you load in your init file.
2120 If you are going to write actual Emacs Lisp programs that go beyond
2121 minor customization, you should read the @cite{Emacs Lisp Reference Manual}.
2123 @xref{Top, Emacs Lisp, Emacs Lisp, elisp, the Emacs Lisp Reference
2128 * Init Syntax:: Syntax of constants in Emacs Lisp.
2129 * Init Examples:: How to do some things with an init file.
2130 * Terminal Init:: Each terminal type can have an init file.
2131 * Find Init:: How Emacs finds the init file.
2132 * Init Non-ASCII:: Using non-@acronym{ASCII} characters in an init file.
2136 @subsection Init File Syntax
2138 The init file contains one or more Lisp expressions. Each of these
2139 consists of a function name followed by arguments, all surrounded by
2140 parentheses. For example, @code{(setq fill-column 60)} calls the
2141 function @code{setq} to set the variable @code{fill-column}
2142 (@pxref{Filling}) to 60.
2144 You can set any Lisp variable with @code{setq}, but with certain
2145 variables @code{setq} won't do what you probably want in the
2146 @file{.emacs} file. Some variables automatically become buffer-local
2147 when set with @code{setq}; what you want in @file{.emacs} is to set
2148 the default value, using @code{setq-default}. Some customizable minor
2149 mode variables do special things to enable the mode when you set them
2150 with Customize, but ordinary @code{setq} won't do that; to enable the
2151 mode in your @file{.emacs} file, call the minor mode command. The
2152 following section has examples of both of these methods.
2154 The second argument to @code{setq} is an expression for the new
2155 value of the variable. This can be a constant, a variable, or a
2156 function call expression. In @file{.emacs}, constants are used most
2157 of the time. They can be:
2161 Numbers are written in decimal, with an optional initial minus sign.
2164 @cindex Lisp string syntax
2165 @cindex string syntax
2166 Lisp string syntax is the same as C string syntax with a few extra
2167 features. Use a double-quote character to begin and end a string constant.
2169 In a string, you can include newlines and special characters literally.
2170 But often it is cleaner to use backslash sequences for them: @samp{\n}
2171 for newline, @samp{\b} for backspace, @samp{\r} for carriage return,
2172 @samp{\t} for tab, @samp{\f} for formfeed (control-L), @samp{\e} for
2173 escape, @samp{\\} for a backslash, @samp{\"} for a double-quote, or
2174 @samp{\@var{ooo}} for the character whose octal code is @var{ooo}.
2175 Backslash and double-quote are the only characters for which backslash
2176 sequences are mandatory.
2178 @samp{\C-} can be used as a prefix for a control character, as in
2179 @samp{\C-s} for @acronym{ASCII} control-S, and @samp{\M-} can be used as a prefix for
2180 a Meta character, as in @samp{\M-a} for @kbd{Meta-A} or @samp{\M-\C-a} for
2181 @kbd{Control-Meta-A}.@refill
2183 @xref{Init Non-ASCII}, for information about including
2184 non-@acronym{ASCII} in your init file.
2187 @cindex Lisp character syntax
2188 @cindex character syntax
2189 Lisp character constant syntax consists of a @samp{?} followed by
2190 either a character or an escape sequence starting with @samp{\}.
2191 Examples: @code{?x}, @code{?\n}, @code{?\"}, @code{?\)}. Note that
2192 strings and characters are not interchangeable in Lisp; some contexts
2193 require one and some contexts require the other.
2195 @xref{Init Non-ASCII}, for information about binding commands to
2196 keys which send non-@acronym{ASCII} characters.
2199 @code{t} stands for `true'.
2202 @code{nil} stands for `false'.
2204 @item Other Lisp objects:
2205 @cindex Lisp object syntax
2206 Write a single-quote (@code{'}) followed by the Lisp object you want.
2210 @subsection Init File Examples
2212 Here are some examples of doing certain commonly desired things with
2217 Add a directory to the variable @code{load-path}. You can then put
2218 Lisp libraries that are not included with Emacs in this directory, and
2219 load them with @kbd{M-x load-library}. @xref{Lisp Libraries}.
2222 (add-to-list 'load-path "/path/to/lisp/libraries")
2226 Make @key{TAB} in C mode just insert a tab if point is in the middle of a
2230 (setq c-tab-always-indent nil)
2233 Here we have a variable whose value is normally @code{t} for `true'
2234 and the alternative is @code{nil} for `false'.
2237 Make searches case sensitive by default (in all buffers that do not
2241 (setq-default case-fold-search nil)
2244 This sets the default value, which is effective in all buffers that do
2245 not have local values for the variable (@pxref{Locals}). Setting
2246 @code{case-fold-search} with @code{setq} affects only the current
2247 buffer's local value, which is probably not what you want to do in an
2251 @vindex user-mail-address
2252 Specify your own email address, if Emacs can't figure it out correctly.
2255 (setq user-mail-address "cheney@@torture.gov")
2258 Various Emacs packages, such as Message mode, consult
2259 @code{user-mail-address} when they need to know your email address.
2260 @xref{Mail Headers}.
2263 Make Text mode the default mode for new buffers.
2266 (setq-default major-mode 'text-mode)
2269 Note that @code{text-mode} is used because it is the command for
2270 entering Text mode. The single-quote before it makes the symbol a
2271 constant; otherwise, @code{text-mode} would be treated as a variable
2276 Set up defaults for the Latin-1 character set
2277 which supports most of the languages of Western Europe.
2280 (set-language-environment "Latin-1")
2285 Turn off Line Number mode, a global minor mode.
2288 (line-number-mode 0)
2293 Turn on Auto Fill mode automatically in Text mode and related modes
2297 (add-hook 'text-mode-hook 'auto-fill-mode)
2301 Load the installed Lisp library named @file{foo} (actually a file
2302 @file{foo.elc} or @file{foo.el} in a standard Emacs directory).
2308 When the argument to @code{load} is a relative file name, not starting
2309 with @samp{/} or @samp{~}, @code{load} searches the directories in
2310 @code{load-path} (@pxref{Lisp Libraries}).
2313 Load the compiled Lisp file @file{foo.elc} from your home directory.
2319 Here a full file name is used, so no searching is done.
2322 @cindex loading Lisp libraries automatically
2323 @cindex autoload Lisp libraries
2324 Tell Emacs to find the definition for the function @code{myfunction}
2325 by loading a Lisp library named @file{mypackage} (i.e.@: a file
2326 @file{mypackage.elc} or @file{mypackage.el}):
2329 (autoload 'myfunction "mypackage" "Do what I say." t)
2333 Here the string @code{"Do what I say."} is the function's
2334 documentation string. You specify it in the @code{autoload}
2335 definition so it will be available for help commands even when the
2336 package is not loaded. The last argument, @code{t}, indicates that
2337 this function is interactive; that is, it can be invoked interactively
2338 by typing @kbd{M-x myfunction @key{RET}} or by binding it to a key.
2339 If the function is not interactive, omit the @code{t} or use
2343 Rebind the key @kbd{C-x l} to run the function @code{make-symbolic-link}
2344 (@pxref{Init Rebinding}).
2347 (global-set-key "\C-xl" 'make-symbolic-link)
2353 (define-key global-map "\C-xl" 'make-symbolic-link)
2356 Note once again the single-quote used to refer to the symbol
2357 @code{make-symbolic-link} instead of its value as a variable.
2360 Do the same thing for Lisp mode only.
2363 (define-key lisp-mode-map "\C-xl" 'make-symbolic-link)
2367 Redefine all keys which now run @code{next-line} in Fundamental mode
2368 so that they run @code{forward-line} instead.
2370 @findex substitute-key-definition
2372 (substitute-key-definition 'next-line 'forward-line
2377 Make @kbd{C-x C-v} undefined.
2380 (global-unset-key "\C-x\C-v")
2383 One reason to undefine a key is so that you can make it a prefix.
2384 Simply defining @kbd{C-x C-v @var{anything}} will make @kbd{C-x C-v} a
2385 prefix, but @kbd{C-x C-v} must first be freed of its usual non-prefix
2389 Make @samp{$} have the syntax of punctuation in Text mode.
2390 Note the use of a character constant for @samp{$}.
2393 (modify-syntax-entry ?\$ "." text-mode-syntax-table)
2397 Enable the use of the command @code{narrow-to-region} without confirmation.
2400 (put 'narrow-to-region 'disabled nil)
2404 Adjusting the configuration to various platforms and Emacs versions.
2406 Users typically want Emacs to behave the same on all systems, so the
2407 same init file is right for all platforms. However, sometimes it
2408 happens that a function you use for customizing Emacs is not available
2409 on some platforms or in older Emacs versions. To deal with that
2410 situation, put the customization inside a conditional that tests whether
2411 the function or facility is available, like this:
2414 (if (fboundp 'blink-cursor-mode)
2415 (blink-cursor-mode 0))
2417 (if (boundp 'coding-category-utf-8)
2418 (set-coding-priority '(coding-category-utf-8)))
2422 You can also simply disregard the errors that occur if the
2423 function is not defined.
2427 (set-face-background 'region "grey75")
2431 A @code{setq} on a variable which does not exist is generally
2432 harmless, so those do not need a conditional.
2436 @subsection Terminal-specific Initialization
2438 Each terminal type can have a Lisp library to be loaded into Emacs when
2439 it is run on that type of terminal. For a terminal type named
2440 @var{termtype}, the library is called @file{term/@var{termtype}} and it is
2441 found by searching the directories @code{load-path} as usual and trying the
2442 suffixes @samp{.elc} and @samp{.el}. Normally it appears in the
2443 subdirectory @file{term} of the directory where most Emacs libraries are
2446 The usual purpose of the terminal-specific library is to map the
2447 escape sequences used by the terminal's function keys onto more
2448 meaningful names, using @code{input-decode-map} (or
2449 @code{function-key-map} before it). See the file
2450 @file{term/lk201.el} for an example of how this is done. Many function
2451 keys are mapped automatically according to the information in the
2452 Termcap data base; the terminal-specific library needs to map only the
2453 function keys that Termcap does not specify.
2455 When the terminal type contains a hyphen, only the part of the name
2456 before the first hyphen is significant in choosing the library name.
2457 Thus, terminal types @samp{aaa-48} and @samp{aaa-30-rv} both use
2458 the library @file{term/aaa}. The code in the library can use
2459 @code{(getenv "TERM")} to find the full terminal type name.@refill
2461 @vindex term-file-prefix
2462 The library's name is constructed by concatenating the value of the
2463 variable @code{term-file-prefix} and the terminal type. Your @file{.emacs}
2464 file can prevent the loading of the terminal-specific library by setting
2465 @code{term-file-prefix} to @code{nil}.
2467 @vindex term-setup-hook
2468 Emacs runs the hook @code{term-setup-hook} at the end of
2469 initialization, after both your @file{.emacs} file and any
2470 terminal-specific library have been read in. Add hook functions to this
2471 hook if you wish to override part of any of the terminal-specific
2472 libraries and to define initializations for terminals that do not have a
2473 library. @xref{Hooks}.
2476 @subsection How Emacs Finds Your Init File
2478 Normally Emacs uses the environment variable @env{HOME}
2479 (@pxref{General Variables, HOME}) to find @file{.emacs}; that's what
2480 @samp{~} means in a file name. If @file{.emacs} is not found inside
2481 @file{~/} (nor @file{.emacs.el}), Emacs looks for
2482 @file{~/.emacs.d/init.el} (which, like @file{~/.emacs.el}, can be
2485 However, if you run Emacs from a shell started by @code{su}, Emacs
2486 tries to find your own @file{.emacs}, not that of the user you are
2487 currently pretending to be. The idea is that you should get your own
2488 editor customizations even if you are running as the super user.
2490 More precisely, Emacs first determines which user's init file to use.
2491 It gets your user name from the environment variables @env{LOGNAME} and
2492 @env{USER}; if neither of those exists, it uses effective user-ID.
2493 If that user name matches the real user-ID, then Emacs uses @env{HOME};
2494 otherwise, it looks up the home directory corresponding to that user
2495 name in the system's data base of users.
2496 @c LocalWords: backtab
2498 @node Init Non-ASCII
2499 @subsection Non-@acronym{ASCII} Characters in Init Files
2500 @cindex international characters in @file{.emacs}
2501 @cindex non-@acronym{ASCII} characters in @file{.emacs}
2502 @cindex non-@acronym{ASCII} keys, binding
2503 @cindex rebinding non-@acronym{ASCII} keys
2505 Language and coding systems may cause problems if your init file
2506 contains non-@acronym{ASCII} characters, such as accented letters, in
2507 strings or key bindings.
2509 If you want to use non-@acronym{ASCII} characters in your init file,
2510 you should put a @w{@samp{-*-coding: @var{coding-system}-*-}} tag on
2511 the first line of the init file, and specify a coding system that
2512 supports the character(s) in question. @xref{Recognize Coding}. This
2513 is because the defaults for decoding non-@acronym{ASCII} text might
2514 not yet be set up by the time Emacs reads those parts of your init
2515 file which use such strings, possibly leading Emacs to decode those
2516 strings incorrectly. You should then avoid adding Emacs Lisp code
2517 that modifies the coding system in other ways, such as calls to
2518 @code{set-language-environment}.
2520 To bind non-@acronym{ASCII} keys, you must use a vector (@pxref{Init
2521 Rebinding}). The string syntax cannot be used, since the
2522 non-@acronym{ASCII} characters will be interpreted as meta keys. For
2526 (global-set-key [?@var{char}] 'some-function)
2530 Type @kbd{C-q}, followed by the key you want to bind, to insert @var{char}.
2532 @strong{Warning:} if you change the keyboard encoding, or change
2533 between multibyte and unibyte mode, or anything that would alter which
2534 code @kbd{C-q} would insert for that character, this key binding may
2535 stop working. It is therefore advisable to use one and only one
2536 coding system, for your init file as well as the files you edit. For
2537 example, don't mix the @samp{latin-1} and @samp{latin-9} coding