This is ../info/emacs, produced by makeinfo version 4.0 from emacs.texi.
This is the thirteenth edition of the `GNU Emacs Manual', updated
for Emacs version 20.7.
INFO-DIR-SECTION Editors
START-INFO-DIR-ENTRY
* Emacs: (emacs). The extensible self-documenting text editor.
END-INFO-DIR-ENTRY
Published by the Free Software Foundation 59 Temple Place, Suite 330
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Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1996, 1997, 1998,
1999 Free Software Foundation, Inc.
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manual into another language, under the above conditions for modified
versions, except that the sections entitled "The GNU Manifesto",
"Distribution" and "GNU General Public License" may be included in a
translation approved by the Free Software Foundation instead of in the
original English.
File: emacs, Node: Specific Customization, Prev: Face Customization, Up: Easy Customization
Customizing Specific Items
..........................
Instead of finding the options you want to change by moving down
through the structure of groups, you can specify the particular option,
face or group that you want to customize.
`M-x customize-option <RET> OPTION <RET>'
Set up a customization buffer with just one option, OPTION.
`M-x customize-face <RET> FACE <RET>'
Set up a customization buffer with just one face, FACE.
`M-x customize-group <RET> GROUP <RET>'
Set up a customization buffer with just one group, GROUP.
`M-x customize-apropos <RET> REGEXP <RET>'
Set up a customization buffer with all the options, faces and
groups that match REGEXP.
`M-x customize-changed-options <RET> VERSION <RET>'
Set up a customization buffer with all the options, faces and
groups whose meaning has changed since Emacs version VERSION.
`M-x customize-saved'
Set up a customization buffer containing all options and faces
that you have saved with customization buffers.
`M-x customize-customized'
Set up a customization buffer containing all options and faces
that you have customized but not saved.
If you want to alter a particular user option variable with the
customization buffer, and you know its name, you can use the command
`M-x customize-option' and specify the option name. This sets up the
customization buffer with just one option--the one that you asked for.
Editing, setting and saving the value work as described above, but only
for the specified option.
Likewise, you can modify a specific face, chosen by name, using `M-x
customize-face'.
You can also set up the customization buffer with a specific group,
using `M-x customize-group'. The immediate contents of the chosen
group, including option variables, faces, and other groups, all appear
as well. However, these subgroups' own contents start out hidden. You
can show their contents in the usual way, by invoking `[Show]'.
To control more precisely what to customize, you can use `M-x
customize-apropos'. You specify a regular expression as argument; then
all options, faces and groups whose names match this regular expression
are set up in the customization buffer. If you specify an empty regular
expression, this includes _all_ groups, options and faces in the
customization buffer (but that takes a long time).
When you upgrade to a new Emacs version, you might want to customize
new options and options whose meanings or default values have changed.
To do this, use `M-x customize-changed-options' and specify a previous
Emacs version number using the minibuffer. It creates a customization
buffer which shows all the options (and groups) whose definitions have
been changed since the specified version.
If you change option values and then decide the change was a mistake,
you can use two special commands to revisit your previous changes. Use
`customize-saved' to look at the options and faces that you have saved.
Use `M-x customize-customized' to look at the options and faces that
you have set but not saved.
File: emacs, Node: Hooks, Next: Locals, Prev: Easy Customization, Up: Variables
Hooks
-----
A "hook" is a variable where you can store a function or functions
to be called on a particular occasion by an existing program. Emacs
provides a number of hooks for the sake of customization.
Most of the hooks in Emacs are "normal hooks". These variables
contain lists of functions to be called with no arguments. The reason
most hooks are normal hooks is so that you can use them in a uniform
way. Every variable in Emacs whose name ends in `-hook' is a normal
hook.
Most major modes run hooks as the last step of initialization. This
makes it easy for a user to customize the behavior of the mode, by
overriding the local variable assignments already made by the mode. But
hooks may also be used in other contexts. For example, the hook
`suspend-hook' runs just before Emacs suspends itself (*note Exiting::).
The recommended way to add a hook function to a normal hook is by
calling `add-hook'. You can use any valid Lisp function as the hook
function. For example, here's how to set up a hook to turn on Auto
Fill mode when entering Text mode and other modes based on Text mode:
(add-hook 'text-mode-hook 'turn-on-auto-fill)
The next example shows how to use a hook to customize the indentation
of C code. (People often have strong personal preferences for one
format compared to another.) Here the hook function is an anonymous
lambda expression.
(setq my-c-style
'((c-comment-only-line-offset . 4)
(c-cleanup-list . (scope-operator
empty-defun-braces
defun-close-semi))
(c-offsets-alist . ((arglist-close . c-lineup-arglist)
(substatement-open . 0)))))
(add-hook 'c-mode-common-hook
(function (lambda ()
(c-add-style "my-style" my-c-style t))))
It is best to design your hook functions so that the order in which
they are executed does not matter. Any dependence on the order is
"asking for trouble." However, the order is predictable: the most
recently added hook functions are executed first.
File: emacs, Node: Locals, Next: File Variables, Prev: Hooks, Up: Variables
Local Variables
---------------
`M-x make-local-variable <RET> VAR <RET>'
Make variable VAR have a local value in the current buffer.
`M-x kill-local-variable <RET> VAR <RET>'
Make variable VAR use its global value in the current buffer.
`M-x make-variable-buffer-local <RET> VAR <RET>'
Mark variable VAR so that setting it will make it local to the
buffer that is current at that time.
Almost any variable can be made "local" to a specific Emacs buffer.
This means that its value in that buffer is independent of its value in
other buffers. A few variables are always local in every buffer.
Every other Emacs variable has a "global" value which is in effect in
all buffers that have not made the variable local.
`M-x make-local-variable' reads the name of a variable and makes it
local to the current buffer. Further changes in this buffer will not
affect others, and further changes in the global value will not affect
this buffer.
`M-x make-variable-buffer-local' reads the name of a variable and
changes the future behavior of the variable so that it will become local
automatically when it is set. More precisely, once a variable has been
marked in this way, the usual ways of setting the variable automatically
do `make-local-variable' first. We call such variables "per-buffer"
variables.
Major modes (*note Major Modes::) always make variables local to the
buffer before setting the variables. This is why changing major modes
in one buffer has no effect on other buffers. Minor modes also work by
setting variables--normally, each minor mode has one controlling
variable which is non-`nil' when the mode is enabled (*note Minor
Modes::). For most minor modes, the controlling variable is per buffer.
Emacs contains a number of variables that are always per-buffer.
These include `abbrev-mode', `auto-fill-function', `case-fold-search',
`comment-column', `ctl-arrow', `fill-column', `fill-prefix',
`indent-tabs-mode', `left-margin', `mode-line-format', `overwrite-mode',
`selective-display-ellipses', `selective-display', `tab-width', and
`truncate-lines'. Some other variables are always local in every
buffer, but they are used for internal purposes.
A few variables cannot be local to a buffer because they are always
local to each display instead (*note Multiple Displays::). If you try
to make one of these variables buffer-local, you'll get an error
message.
`M-x kill-local-variable' reads the name of a variable and makes it
cease to be local to the current buffer. The global value of the
variable henceforth is in effect in this buffer. Setting the major mode
kills all the local variables of the buffer except for a few variables
specially marked as "permanent locals".
To set the global value of a variable, regardless of whether the
variable has a local value in the current buffer, you can use the Lisp
construct `setq-default'. This construct is used just like `setq', but
it sets variables' global values instead of their local values (if
any). When the current buffer does have a local value, the new global
value may not be visible until you switch to another buffer. Here is
an example:
(setq-default fill-column 75)
`setq-default' is the only way to set the global value of a variable
that has been marked with `make-variable-buffer-local'.
Lisp programs can use `default-value' to look at a variable's
default value. This function takes a symbol as argument and returns its
default value. The argument is evaluated; usually you must quote it
explicitly. For example, here's how to obtain the default value of
`fill-column':
(default-value 'fill-column)
File: emacs, Node: File Variables, Prev: Locals, Up: Variables
Local Variables in Files
------------------------
A file can specify local variable values for use when you edit the
file with Emacs. Visiting the file checks for local variable
specifications; it automatically makes these variables local to the
buffer, and sets them to the values specified in the file.
There are two ways to specify local variable values: in the first
line, or with a local variables list. Here's how to specify them in the
first line:
-*- mode: MODENAME; VAR: VALUE; ... -*-
You can specify any number of variables/value pairs in this way, each
pair with a colon and semicolon as shown above. `mode: MODENAME;'
specifies the major mode; this should come first in the line. The
VALUEs are not evaluated; they are used literally. Here is an example
that specifies Lisp mode and sets two variables with numeric values:
;; -*-mode: Lisp; fill-column: 75; comment-column: 50; -*-
You can also specify the coding system for a file in this way: just
specify a value for the "variable" named `coding'. The "value" must be
a coding system name that Emacs recognizes. *Note Coding Systems::.
A "local variables list" goes near the end of the file, in the last
page. (It is often best to put it on a page by itself.) The local
variables list starts with a line containing the string `Local
Variables:', and ends with a line containing the string `End:'. In
between come the variable names and values, one set per line, as
`VARIABLE: VALUE'. The VALUEs are not evaluated; they are used
literally. If a file has both a local variables list and a `-*-' line,
Emacs processes _everything_ in the `-*-' line first, and _everything_
in the local variables list afterward.
Here is an example of a local variables list:
;;; Local Variables: ***
;;; mode:lisp ***
;;; comment-column:0 ***
;;; comment-start: ";;; " ***
;;; comment-end:"***" ***
;;; End: ***
As you see, each line starts with the prefix `;;; ' and each line
ends with the suffix ` ***'. Emacs recognizes these as the prefix and
suffix based on the first line of the list, by finding them surrounding
the magic string `Local Variables:'; then it automatically discards
them from the other lines of the list.
The usual reason for using a prefix and/or suffix is to embed the
local variables list in a comment, so it won't confuse other programs
that the file is intended as input for. The example above is for a
language where comment lines start with `;;; ' and end with `***'; the
local values for `comment-start' and `comment-end' customize the rest
of Emacs for this unusual syntax. Don't use a prefix (or a suffix) if
you don't need one.
Two "variable names" have special meanings in a local variables
list: a value for the variable `mode' really sets the major mode, and a
value for the variable `eval' is simply evaluated as an expression and
the value is ignored. `mode' and `eval' are not real variables;
setting variables named `mode' and `eval' in any other context has no
special meaning. If `mode' is used to set a major mode, it should be
the first "variable" in the list.
You can use the `mode' "variable" to set minor modes as well as
major modes; in fact, you can use it more than once, first to set the
major mode and then to set minor modes which are specific to particular
buffers. But most minor modes should not be specified in the file in
any fashion, because they represent user preferences.
For example, you may be tempted to try to turn on Auto Fill mode with
a local variable list. That is a mistake. The choice of Auto Fill mode
or not is a matter of individual taste, not a matter of the contents of
particular files. If you want to use Auto Fill, set up major mode hooks
with your `.emacs' file to turn it on (when appropriate) for you alone
(*note Init File::). Don't use a local variable list to impose your
taste on everyone.
The start of the local variables list must be no more than 3000
characters from the end of the file, and must be in the last page if the
file is divided into pages. Otherwise, Emacs will not notice it is
there. The purpose of this rule is so that a stray `Local Variables:'
not in the last page does not confuse Emacs, and so that visiting a
long file that is all one page and has no local variables list need not
take the time to search the whole file.
Use the command `normal-mode' to reset the local variables and major
mode of a buffer according to the file name and contents, including the
local variables list if any. *Note Choosing Modes::.
The variable `enable-local-variables' controls whether to process
local variables in files, and thus gives you a chance to override them.
Its default value is `t', which means do process local variables in
files. If you set the value to `nil', Emacs simply ignores local
variables in files. Any other value says to query you about each file
that has local variables, showing you the local variable specifications
so you can judge.
The `eval' "variable," and certain actual variables, create a
special risk; when you visit someone else's file, local variable
specifications for these could affect your Emacs in arbitrary ways.
Therefore, the option `enable-local-eval' controls whether Emacs
processes `eval' variables, as well variables with names that end in
`-hook', `-hooks', `-function' or `-functions', and certain other
variables. The three possibilities for the option's value are `t',
`nil', and anything else, just as for `enable-local-variables'. The
default is `maybe', which is neither `t' nor `nil', so normally Emacs
does ask for confirmation about file settings for these variables.
File: emacs, Node: Keyboard Macros, Next: Key Bindings, Prev: Variables, Up: Customization
Keyboard Macros
===============
A "keyboard macro" is a command defined by the user to stand for
another sequence of keys. For example, if you discover that you are
about to type `C-n C-d' forty times, you can speed your work by
defining a keyboard macro to do `C-n C-d' and calling it with a repeat
count of forty.
`C-x ('
Start defining a keyboard macro (`start-kbd-macro').
`C-x )'
End the definition of a keyboard macro (`end-kbd-macro').
`C-x e'
Execute the most recent keyboard macro (`call-last-kbd-macro').
`C-u C-x ('
Re-execute last keyboard macro, then add more keys to its
definition.
`C-x q'
When this point is reached during macro execution, ask for
confirmation (`kbd-macro-query').
`M-x name-last-kbd-macro'
Give a command name (for the duration of the session) to the most
recently defined keyboard macro.
`M-x insert-kbd-macro'
Insert in the buffer a keyboard macro's definition, as Lisp code.
`C-x C-k'
Edit a previously defined keyboard macro (`edit-kbd-macro').
`M-x apply-macro-to-region-lines'
Run the last keyboard macro on each complete line in the region.
Keyboard macros differ from ordinary Emacs commands in that they are
written in the Emacs command language rather than in Lisp. This makes
it easier for the novice to write them, and makes them more convenient
as temporary hacks. However, the Emacs command language is not powerful
enough as a programming language to be useful for writing anything
intelligent or general. For such things, Lisp must be used.
You define a keyboard macro while executing the commands which are
the definition. Put differently, as you define a keyboard macro, the
definition is being executed for the first time. This way, you can see
what the effects of your commands are, so that you don't have to figure
them out in your head. When you are finished, the keyboard macro is
defined and also has been, in effect, executed once. You can then do
the whole thing over again by invoking the macro.
* Menu:
* Basic Kbd Macro:: Defining and running keyboard macros.
* Save Kbd Macro:: Giving keyboard macros names; saving them in files.
* Kbd Macro Query:: Making keyboard macros do different things each time.
File: emacs, Node: Basic Kbd Macro, Next: Save Kbd Macro, Up: Keyboard Macros
Basic Use
---------
To start defining a keyboard macro, type the `C-x (' command
(`start-kbd-macro'). From then on, your keys continue to be executed,
but also become part of the definition of the macro. `Def' appears in
the mode line to remind you of what is going on. When you are
finished, the `C-x )' command (`end-kbd-macro') terminates the
definition (without becoming part of it!). For example,
C-x ( M-f foo C-x )
defines a macro to move forward a word and then insert `foo'.
The macro thus defined can be invoked again with the `C-x e' command
(`call-last-kbd-macro'), which may be given a repeat count as a numeric
argument to execute the macro many times. `C-x )' can also be given a
repeat count as an argument, in which case it repeats the macro that
many times right after defining it, but defining the macro counts as
the first repetition (since it is executed as you define it).
Therefore, giving `C-x )' an argument of 4 executes the macro
immediately 3 additional times. An argument of zero to `C-x e' or `C-x
)' means repeat the macro indefinitely (until it gets an error or you
type `C-g' or, on MS-DOS, `C-<BREAK>').
If you wish to repeat an operation at regularly spaced places in the
text, define a macro and include as part of the macro the commands to
move to the next place you want to use it. For example, if you want to
change each line, you should position point at the start of a line, and
define a macro to change that line and leave point at the start of the
next line. Then repeating the macro will operate on successive lines.
After you have terminated the definition of a keyboard macro, you
can add to the end of its definition by typing `C-u C-x ('. This is
equivalent to plain `C-x (' followed by retyping the whole definition
so far. As a consequence it re-executes the macro as previously
defined.
You can use function keys in a keyboard macro, just like keyboard
keys. You can even use mouse events, but be careful about that: when
the macro replays the mouse event, it uses the original mouse position
of that event, the position that the mouse had while you were defining
the macro. The effect of this may be hard to predict. (Using the
current mouse position would be even less predictable.)
One thing that doesn't always work well in a keyboard macro is the
command `C-M-c' (`exit-recursive-edit'). When this command exits a
recursive edit that started within the macro, it works as you'd expect.
But if it exits a recursive edit that started before you invoked the
keyboard macro, it also necessarily exits the keyboard macro as part of
the process.
You can edit a keyboard macro already defined by typing `C-x C-k'
(`edit-kbd-macro'). Follow that with the keyboard input that you would
use to invoke the macro--`C-x e' or `M-x NAME' or some other key
sequence. This formats the macro definition in a buffer and enters a
specialized major mode for editing it. Type `C-h m' once in that
buffer to display details of how to edit the macro. When you are
finished editing, type `C-c C-c'.
The command `M-x apply-macro-to-region-lines' repeats the last
defined keyboard macro on each complete line within the current region.
It does this line by line, by moving point to the beginning of the line
and then executing the macro.
File: emacs, Node: Save Kbd Macro, Next: Kbd Macro Query, Prev: Basic Kbd Macro, Up: Keyboard Macros
Naming and Saving Keyboard Macros
---------------------------------
If you wish to save a keyboard macro for longer than until you
define the next one, you must give it a name using `M-x
name-last-kbd-macro'. This reads a name as an argument using the
minibuffer and defines that name to execute the macro. The macro name
is a Lisp symbol, and defining it in this way makes it a valid command
name for calling with `M-x' or for binding a key to with
`global-set-key' (*note Keymaps::). If you specify a name that has a
prior definition other than another keyboard macro, an error message is
printed and nothing is changed.
Once a macro has a command name, you can save its definition in a
file. Then it can be used in another editing session. First, visit
the file you want to save the definition in. Then use this command:
M-x insert-kbd-macro <RET> MACRONAME <RET>
This inserts some Lisp code that, when executed later, will define the
same macro with the same definition it has now. (You need not
understand Lisp code to do this, because `insert-kbd-macro' writes the
Lisp code for you.) Then save the file. You can load the file later
with `load-file' (*note Lisp Libraries::). If the file you save in is
your init file `~/.emacs' (*note Init File::) then the macro will be
defined each time you run Emacs.
If you give `insert-kbd-macro' a numeric argument, it makes
additional Lisp code to record the keys (if any) that you have bound to
the keyboard macro, so that the macro will be reassigned the same keys
when you load the file.
File: emacs, Node: Kbd Macro Query, Prev: Save Kbd Macro, Up: Keyboard Macros
Executing Macros with Variations
--------------------------------
Using `C-x q' (`kbd-macro-query'), you can get an effect similar to
that of `query-replace', where the macro asks you each time around
whether to make a change. While defining the macro, type `C-x q' at
the point where you want the query to occur. During macro definition,
the `C-x q' does nothing, but when you run the macro later, `C-x q'
asks you interactively whether to continue.
The valid responses when `C-x q' asks are <SPC> (or `y'), <DEL> (or
`n'), <RET> (or `q'), `C-l' and `C-r'. The answers are the same as in
`query-replace', though not all of the `query-replace' options are
meaningful.
These responses include <SPC> to continue, and <DEL> to skip the
remainder of this repetition of the macro and start right away with the
next repetition. <RET> means to skip the remainder of this repetition
and cancel further repetitions. `C-l' redraws the screen and asks you
again for a character to say what to do.
`C-r' enters a recursive editing level, in which you can perform
editing which is not part of the macro. When you exit the recursive
edit using `C-M-c', you are asked again how to continue with the
keyboard macro. If you type a <SPC> at this time, the rest of the
macro definition is executed. It is up to you to leave point and the
text in a state such that the rest of the macro will do what you want.
`C-u C-x q', which is `C-x q' with a numeric argument, performs a
completely different function. It enters a recursive edit reading
input from the keyboard, both when you type it during the definition of
the macro, and when it is executed from the macro. During definition,
the editing you do inside the recursive edit does not become part of
the macro. During macro execution, the recursive edit gives you a
chance to do some particularized editing on each repetition. *Note
Recursive Edit::.
File: emacs, Node: Key Bindings, Next: Keyboard Translations, Prev: Keyboard Macros, Up: Customization
Customizing Key Bindings
========================
This section describes "key bindings", which map keys to commands,
and "keymaps", which record key bindings. It also explains how to
customize key bindings.
Recall that a command is a Lisp function whose definition provides
for interactive use. Like every Lisp function, a command has a function
name which usually consists of lower-case letters and hyphens.
* Menu:
* Keymaps:: Generalities. The global keymap.
* Prefix Keymaps:: Keymaps for prefix keys.
* Local Keymaps:: Major and minor modes have their own keymaps.
* Minibuffer Maps:: The minibuffer uses its own local keymaps.
* Rebinding:: How to redefine one key's meaning conveniently.
* Init Rebinding:: Rebinding keys with your init file, `.emacs'.
* Function Keys:: Rebinding terminal function keys.
* Named ASCII Chars:: Distinguishing <TAB> from C-i, and so on.
* Non-ASCII Rebinding:: Rebinding non-ASCII characters such as Latin-1.
* Mouse Buttons:: Rebinding mouse buttons in Emacs.
* Disabling:: Disabling a command means confirmation is required
before it can be executed. This is done to protect
beginners from surprises.
File: emacs, Node: Keymaps, Next: Prefix Keymaps, Up: Key Bindings
Keymaps
-------
The bindings between key sequences and command functions are recorded
in data structures called "keymaps". Emacs has many of these, each
used on particular occasions.
Recall that a "key sequence" ("key", for short) is a sequence of
"input events" that have a meaning as a unit. Input events include
characters, function keys and mouse buttons--all the inputs that you
can send to the computer with your terminal. A key sequence gets its
meaning from its "binding", which says what command it runs. The
function of keymaps is to record these bindings.
The "global" keymap is the most important keymap because it is
always in effect. The global keymap defines keys for Fundamental mode;
most of these definitions are common to most or all major modes. Each
major or minor mode can have its own keymap which overrides the global
definitions of some keys.
For example, a self-inserting character such as `g' is
self-inserting because the global keymap binds it to the command
`self-insert-command'. The standard Emacs editing characters such as
`C-a' also get their standard meanings from the global keymap.
Commands to rebind keys, such as `M-x global-set-key', actually work by
storing the new binding in the proper place in the global map. *Note
Rebinding::.
Meta characters work differently; Emacs translates each Meta
character into a pair of characters starting with <ESC>. When you type
the character `M-a' in a key sequence, Emacs replaces it with `<ESC>
a'. A meta key comes in as a single input event, but becomes two
events for purposes of key bindings. The reason for this is
historical, and we might change it someday.
Most modern keyboards have function keys as well as character keys.
Function keys send input events just as character keys do, and keymaps
can have bindings for them.
On many terminals, typing a function key actually sends the computer
a sequence of characters; the precise details of the sequence depends on
which function key and on the model of terminal you are using. (Often
the sequence starts with `<ESC> ['.) If Emacs understands your
terminal type properly, it recognizes the character sequences forming
function keys wherever they occur in a key sequence (not just at the
beginning). Thus, for most purposes, you can pretend the function keys
reach Emacs directly and ignore their encoding as character sequences.
Mouse buttons also produce input events. These events come with
other data--the window and position where you pressed or released the
button, and a time stamp. But only the choice of button matters for key
bindings; the other data matters only if a command looks at it.
(Commands designed for mouse invocation usually do look at the other
data.)
A keymap records definitions for single events. Interpreting a key
sequence of multiple events involves a chain of keymaps. The first
keymap gives a definition for the first event; this definition is
another keymap, which is used to look up the second event in the
sequence, and so on.
Key sequences can mix function keys and characters. For example,
`C-x <SELECT>' is meaningful. If you make <SELECT> a prefix key, then
`<SELECT> C-n' makes sense. You can even mix mouse events with
keyboard events, but we recommend against it, because such sequences
are inconvenient to type in.
As a user, you can redefine any key; but it might be best to stick to
key sequences that consist of `C-c' followed by a letter. These keys
are "reserved for users," so they won't conflict with any properly
designed Emacs extension. The function keys <F5> through <F9> are also
reserved for users. If you redefine some other key, your definition
may be overridden by certain extensions or major modes which redefine
the same key.
File: emacs, Node: Prefix Keymaps, Next: Local Keymaps, Prev: Keymaps, Up: Key Bindings
Prefix Keymaps
--------------
A prefix key such as `C-x' or <ESC> has its own keymap, which holds
the definition for the event that immediately follows that prefix.
The definition of a prefix key is usually the keymap to use for
looking up the following event. The definition can also be a Lisp
symbol whose function definition is the following keymap; the effect is
the same, but it provides a command name for the prefix key that can be
used as a description of what the prefix key is for. Thus, the binding
of `C-x' is the symbol `Ctl-X-Prefix', whose function definition is the
keymap for `C-x' commands. The definitions of `C-c', `C-x', `C-h' and
<ESC> as prefix keys appear in the global map, so these prefix keys are
always available.
Aside from ordinary prefix keys, there is a fictitious "prefix key"
which represents the menu bar; see *Note Menu Bar: (elisp)Menu Bar, for
special information about menu bar key bindings. Mouse button events
that invoke pop-up menus are also prefix keys; see *Note Menu Keymaps:
(elisp)Menu Keymaps, for more details.
Some prefix keymaps are stored in variables with names:
* `ctl-x-map' is the variable name for the map used for characters
that follow `C-x'.
* `help-map' is for characters that follow `C-h'.
* `esc-map' is for characters that follow <ESC>. Thus, all Meta
characters are actually defined by this map.
* `ctl-x-4-map' is for characters that follow `C-x 4'.
* `mode-specific-map' is for characters that follow `C-c'.
File: emacs, Node: Local Keymaps, Next: Minibuffer Maps, Prev: Prefix Keymaps, Up: Key Bindings
Local Keymaps
-------------
So far we have explained the ins and outs of the global map. Major
modes customize Emacs by providing their own key bindings in "local
keymaps". For example, C mode overrides <TAB> to make it indent the
current line for C code. Portions of text in the buffer can specify
their own keymaps to substitute for the keymap of the buffer's major
mode.
Minor modes can also have local keymaps. Whenever a minor mode is
in effect, the definitions in its keymap override both the major mode's
local keymap and the global keymap.
The local keymaps for Lisp mode and several other major modes always
exist even when not in use. These are kept in variables named
`lisp-mode-map' and so on. For major modes less often used, the local
keymap is normally constructed only when the mode is used for the first
time in a session. This is to save space. If you wish to change one
of these keymaps, you must use the major mode's "mode hook"--see below.
All minor mode keymaps are created in advance. There is no way to
defer their creation until the first time the minor mode is enabled.
A local keymap can locally redefine a key as a prefix key by defining
it as a prefix keymap. If the key is also defined globally as a prefix,
then its local and global definitions (both keymaps) effectively
combine: both of them are used to look up the event that follows the
prefix key. Thus, if the mode's local keymap defines `C-c' as another
keymap, and that keymap defines `C-z' as a command, this provides a
local meaning for `C-c C-z'. This does not affect other sequences that
start with `C-c'; if those sequences don't have their own local
bindings, their global bindings remain in effect.
Another way to think of this is that Emacs handles a multi-event key
sequence by looking in several keymaps, one by one, for a binding of the
whole key sequence. First it checks the minor mode keymaps for minor
modes that are enabled, then it checks the major mode's keymap, and then
it checks the global keymap. This is not precisely how key lookup
works, but it's good enough for understanding ordinary circumstances.
To change the local bindings of a major mode, you must change the
mode's local keymap. Normally you must wait until the first time the
mode is used, because most major modes don't create their keymaps until
then. If you want to specify something in your `~/.emacs' file to
change a major mode's bindings, you must use the mode's mode hook to
delay the change until the mode is first used.
For example, the command `texinfo-mode' to select Texinfo mode runs
the hook `texinfo-mode-hook'. Here's how you can use the hook to add
local bindings (not very useful, we admit) for `C-c n' and `C-c p' in
Texinfo mode:
(add-hook 'texinfo-mode-hook
'(lambda ()
(define-key texinfo-mode-map
"\C-cp"
'backward-paragraph)
(define-key texinfo-mode-map
"\C-cn"
'forward-paragraph)
))
*Note Hooks::.
File: emacs, Node: Minibuffer Maps, Next: Rebinding, Prev: Local Keymaps, Up: Key Bindings
Minibuffer Keymaps
------------------
The minibuffer has its own set of local keymaps; they contain various
completion and exit commands.
* `minibuffer-local-map' is used for ordinary input (no completion).
* `minibuffer-local-ns-map' is similar, except that <SPC> exits just
like <RET>. This is used mainly for Mocklisp compatibility.
* `minibuffer-local-completion-map' is for permissive completion.
* `minibuffer-local-must-match-map' is for strict completion and for
cautious completion.
File: emacs, Node: Rebinding, Next: Init Rebinding, Prev: Minibuffer Maps, Up: Key Bindings
Changing Key Bindings Interactively
-----------------------------------
The way to redefine an Emacs key is to change its entry in a keymap.
You can change the global keymap, in which case the change is effective
in all major modes (except those that have their own overriding local
definitions for the same key). Or you can change the current buffer's
local map, which affects all buffers using the same major mode.
`M-x global-set-key <RET> KEY CMD <RET>'
Define KEY globally to run CMD.
`M-x local-set-key <RET> KEY CMD <RET>'
Define KEY locally (in the major mode now in effect) to run CMD.
`M-x global-unset-key <RET> KEY'
Make KEY undefined in the global map.
`M-x local-unset-key <RET> KEY'
Make KEY undefined locally (in the major mode now in effect).
For example, suppose you like to execute commands in a subshell
within an Emacs buffer, instead of suspending Emacs and executing
commands in your login shell. Normally, `C-z' is bound to the function
`suspend-emacs' (when not using the X Window System), but you can
change `C-z' to invoke an interactive subshell within Emacs, by binding
it to `shell' as follows:
M-x global-set-key <RET> C-z shell <RET>
`global-set-key' reads the command name after the key. After you
press the key, a message like this appears so that you can confirm that
you are binding the key you want:
Set key C-z to command:
You can redefine function keys and mouse events in the same way; just
type the function key or click the mouse when it's time to specify the
key to rebind.
You can rebind a key that contains more than one event in the same
way. Emacs keeps reading the key to rebind until it is a complete key
(that is, not a prefix key). Thus, if you type `C-f' for KEY, that's
the end; the minibuffer is entered immediately to read CMD. But if you
type `C-x', another character is read; if that is `4', another
character is read, and so on. For example,
M-x global-set-key <RET> C-x 4 $ spell-other-window <RET>
redefines `C-x 4 $' to run the (fictitious) command
`spell-other-window'.
The two-character keys consisting of `C-c' followed by a letter are
reserved for user customizations. Lisp programs are not supposed to
define these keys, so the bindings you make for them will be available
in all major modes and will never get in the way of anything.
You can remove the global definition of a key with
`global-unset-key'. This makes the key "undefined"; if you type it,
Emacs will just beep. Similarly, `local-unset-key' makes a key
undefined in the current major mode keymap, which makes the global
definition (or lack of one) come back into effect in that major mode.
If you have redefined (or undefined) a key and you subsequently wish
to retract the change, undefining the key will not do the job--you need
to redefine the key with its standard definition. To find the name of
the standard definition of a key, go to a Fundamental mode buffer and
use `C-h c'. The documentation of keys in this manual also lists their
command names.
If you want to prevent yourself from invoking a command by mistake,
it is better to disable the command than to undefine the key. A
disabled command is less work to invoke when you really want to. *Note
Disabling::.
File: emacs, Node: Init Rebinding, Next: Function Keys, Prev: Rebinding, Up: Key Bindings
Rebinding Keys in Your Init File
--------------------------------
If you have a set of key bindings that you like to use all the time,
you can specify them in your `.emacs' file by using their Lisp syntax.
The simplest method for doing this works for ASCII characters and
Meta-modified ASCII characters only. This method uses a string to
represent the key sequence you want to rebind. For example, here's how
to bind `C-z' to `shell':
(global-set-key "\C-z" 'shell)
This example uses a string constant containing one character, `C-z'.
The single-quote before the command name, `shell', marks it as a
constant symbol rather than a variable. If you omit the quote, Emacs
would try to evaluate `shell' immediately as a variable. This probably
causes an error; it certainly isn't what you want.
Here is another example that binds a key sequence two characters
long:
(global-set-key "\C-xl" 'make-symbolic-link)
When the key sequence includes function keys or mouse button events,
or non-ASCII characters such as `C-=' or `H-a', you must use the more
general method of rebinding, which uses a vector to specify the key
sequence.
The way to write a vector in Emacs Lisp is with square brackets
around the vector elements. Use spaces to separate the elements. If an
element is a symbol, simply write the symbol's name--no other
delimiters or punctuation are needed. If a vector element is a
character, write it as a Lisp character constant: `?' followed by the
character as it would appear in a string.
Here are examples of using vectors to rebind `C-=' (a control
character outside of ASCII), `H-a' (a Hyper character; ASCII doesn't
have Hyper at all), <F7> (a function key), and `C-Mouse-1' (a
keyboard-modified mouse button):
(global-set-key [?\C-=] 'make-symbolic-link)
(global-set-key [?\H-a] 'make-symbolic-link)
(global-set-key [f7] 'make-symbolic-link)
(global-set-key [C-mouse-1] 'make-symbolic-link)
You can use a vector for the simple cases too. Here's how to rewrite
the first two examples, above, to use vectors:
(global-set-key [?\C-z] 'shell)
(global-set-key [?\C-x ?l] 'make-symbolic-link)
File: emacs, Node: Function Keys, Next: Named ASCII Chars, Prev: Init Rebinding, Up: Key Bindings
Rebinding Function Keys
-----------------------
Key sequences can contain function keys as well as ordinary
characters. Just as Lisp characters (actually integers) represent
keyboard characters, Lisp symbols represent function keys. If the
function key has a word as its label, then that word is also the name of
the corresponding Lisp symbol. Here are the conventional Lisp names for
common function keys:
`left', `up', `right', `down'
Cursor arrow keys.
`begin', `end', `home', `next', `prior'
Other cursor repositioning keys.
`select', `print', `execute', `backtab'
`insert', `undo', `redo', `clearline'
`insertline', `deleteline', `insertchar', `deletechar',
Miscellaneous function keys.
`f1', `f2', ... `f35'
Numbered function keys (across the top of the keyboard).
`kp-add', `kp-subtract', `kp-multiply', `kp-divide'
`kp-backtab', `kp-space', `kp-tab', `kp-enter'
`kp-separator', `kp-decimal', `kp-equal'
Keypad keys (to the right of the regular keyboard), with names or
punctuation.
`kp-0', `kp-1', ... `kp-9'
Keypad keys with digits.
`kp-f1', `kp-f2', `kp-f3', `kp-f4'
Keypad PF keys.
These names are conventional, but some systems (especially when using
X windows) may use different names. To make certain what symbol is used
for a given function key on your terminal, type `C-h c' followed by
that key.
A key sequence which contains function key symbols (or anything but
ASCII characters) must be a vector rather than a string. The vector
syntax uses spaces between the elements, and square brackets around the
whole vector. Thus, to bind function key `f1' to the command `rmail',
write the following:
(global-set-key [f1] 'rmail)
To bind the right-arrow key to the command `forward-char', you can use
this expression:
(global-set-key [right] 'forward-char)
This uses the Lisp syntax for a vector containing the symbol `right'.
(This binding is present in Emacs by default.)
*Note Init Rebinding::, for more information about using vectors for
rebinding.
You can mix function keys and characters in a key sequence. This
example binds `C-x <NEXT>' to the command `forward-page'.
(global-set-key [?\C-x next] 'forward-page)
where `?\C-x' is the Lisp character constant for the character `C-x'.
The vector element `next' is a symbol and therefore does not take a
question mark.
You can use the modifier keys <CTRL>, <META>, <HYPER>, <SUPER>,
<ALT> and <SHIFT> with function keys. To represent these modifiers,
add the strings `C-', `M-', `H-', `s-', `A-' and `S-' at the front of
the symbol name. Thus, here is how to make `Hyper-Meta-<RIGHT>' move
forward a word:
(global-set-key [H-M-right] 'forward-word)
File: emacs, Node: Named ASCII Chars, Next: Non-ASCII Rebinding, Prev: Function Keys, Up: Key Bindings
Named ASCII Control Characters
------------------------------
<TAB>, <RET>, <BS>, <LFD>, <ESC> and <DEL> started out as names for
certain ASCII control characters, used so often that they have special
keys of their own. Later, users found it convenient to distinguish in
Emacs between these keys and the "same" control characters typed with
the <CTRL> key.
Emacs distinguishes these two kinds of input, when used with the X
Window System. It treats the "special" keys as function keys named
`tab', `return', `backspace', `linefeed', `escape', and `delete'.
These function keys translate automatically into the corresponding
ASCII characters _if_ they have no bindings of their own. As a result,
neither users nor Lisp programs need to pay attention to the
distinction unless they care to.
If you do not want to distinguish between (for example) <TAB> and
`C-i', make just one binding, for the ASCII character <TAB> (octal code
011). If you do want to distinguish, make one binding for this ASCII
character, and another for the "function key" `tab'.
With an ordinary ASCII terminal, there is no way to distinguish
between <TAB> and `C-i' (and likewise for other such pairs), because
the terminal sends the same character in both cases.
File: emacs, Node: Non-ASCII Rebinding, Next: Mouse Buttons, Prev: Named ASCII Chars, Up: Key Bindings
Non-ASCII Characters on the Keyboard
------------------------------------
If your keyboard has keys that send non-ASCII characters, such as
accented letters, rebinding these keys is a bit tricky. There are two
solutions you can use. One is to specify a keyboard coding system,
using `set-keyboard-coding-system' (*note Specify Coding::). Then you
can bind these keys in the usual way, but writing
(global-set-key [?CHAR] 'some-function)
and typing the key you want to bind to insert CHAR.
If you don't specify the keyboard coding system, that approach won't
work. Instead, you need to find out the actual code that the terminal
sends. The easiest way to do this in Emacs is to create an empty buffer
with `C-x b temp <RET>', make it unibyte with `M-x
toggle-enable-multibyte-characters <RET>', then type the key to insert
the character into this buffer.
Move point before the character, then type `C-b C-x ='. This
displays a message in the minibuffer, showing the character code in
three ways, octal, decimal and hexadecimal, all within a set of
parentheses. Use the second of the three numbers, the decimal one,
inside the vector to bind:
(global-set-key [DECIMAL-CODE] 'some-function)