The way to rebind a key is to change its entry in a keymap. If you
change a binding in the global keymap, the change is effective in all
buffers (though it has no direct effect in buffers that shadow the
global binding with a local one). If you change the current buffer’s
local map, that usually affects all buffers using the same major mode.
local-set-key functions are
convenient interfaces for these operations (see Key Binding Commands). You can also use
define-key, a more general
function; then you must explicitly specify the map to change.
When choosing the key sequences for Lisp programs to rebind, please follow the Emacs conventions for use of various keys (see Key Binding Conventions).
In writing the key sequence to rebind, it is good to use the special
escape sequences for control and meta characters (see String Type).
The syntax ‘\C-’ means that the following character is a control
character and ‘\M-’ means that the following character is a meta
character. Thus, the string
"\M-x" is read as containing a
"\C-f" is read as containing a single
"\C-\M-x" are both read as
containing a single C-M-x. You can also use this escape syntax in
vectors, as well as others that aren’t allowed in strings; one example
is ‘[?\C-\H-x home]’. See Character Type.
The key definition and lookup functions accept an alternate syntax for
event types in a key sequence that is a vector: you can use a list
containing modifier names plus one base event (a character or function
key name). For example,
(control ?a) is equivalent to
(hyper control left) is equivalent to
C-H-left. One advantage of such lists is that the precise
numeric codes for the modifier bits don’t appear in compiled files.
The functions below signal an error if keymap is not a keymap,
or if key is not a string or vector representing a key sequence.
You can use event types (symbols) as shorthand for events that are
kbd function (see Key Sequences) is a
convenient way to specify the key sequence.
This function sets the binding for key in keymap. (If
key is more than one event long, the change is actually made
in another keymap reached from keymap.) The argument
binding can be any Lisp object, but only certain types are
meaningful. (For a list of meaningful types, see Key Lookup.)
The value returned by
define-key is binding.
If key is
[t], this sets the default binding in
keymap. When an event has no binding of its own, the Emacs
command loop uses the keymap’s default binding, if there is one.
Every prefix of key must be a prefix key (i.e., bound to a keymap)
or undefined; otherwise an error is signaled. If some prefix of
key is undefined, then
define-key defines it as a prefix
key so that the rest of key can be defined as specified.
If there was previously no binding for key in keymap, the new binding is added at the beginning of keymap. The order of bindings in a keymap makes no difference for keyboard input, but it does matter for menu keymaps (see Menu Keymaps).
This example creates a sparse keymap and makes a number of bindings in it:
(setq map (make-sparse-keymap)) ⇒ (keymap)
(define-key map "\C-f" 'forward-char) ⇒ forward-char
map ⇒ (keymap (6 . forward-char))
;; Build sparse submap for C-x and bind f in that. (define-key map (kbd "C-x f") 'forward-word) ⇒ forward-word
map ⇒ (keymap (24 keymap ; C-x (102 . forward-word)) ; f (6 . forward-char)) ; C-f
;; Bind C-p to the
ctl-x-map. (define-key map (kbd "C-p") ctl-x-map) ;;
ctl-x-map⇒ [nil … find-file … backward-kill-sentence]
;; Bind C-f to
ctl-x-map. (define-key map (kbd "C-p C-f") 'foo) ⇒ 'foo
map ⇒ (keymap ; Note
ctl-x-map. (16 keymap [nil … foo … backward-kill-sentence]) (24 keymap (102 . forward-word)) (6 . forward-char))
Note that storing a new binding for C-p C-f actually works by
changing an entry in
ctl-x-map, and this has the effect of
changing the bindings of both C-p C-f and C-x C-f in the
default global map.
substitute-key-definition scans a keymap for
keys that have a certain binding and rebinds them with a different
binding. Another feature which is cleaner and can often produce the
same results is to remap one command into another (see Remapping Commands).
This function replaces olddef with newdef for any keys in
keymap that were bound to olddef. In other words,
olddef is replaced with newdef wherever it appears. The
For example, this redefines C-x C-f, if you do it in an Emacs with standard bindings:
(substitute-key-definition 'find-file 'find-file-read-only (current-global-map))
If oldmap is non-
nil, that changes the behavior of
substitute-key-definition: the bindings in oldmap determine
which keys to rebind. The rebindings still happen in keymap, not
in oldmap. Thus, you can change one map under the control of the
bindings in another. For example,
(substitute-key-definition 'delete-backward-char 'my-funny-delete my-map global-map)
puts the special deletion command in
my-map for whichever keys
are globally bound to the standard deletion command.
Here is an example showing a keymap before and after substitution:
(setq map (list 'keymap (cons ?1 olddef-1) (cons ?2 olddef-2) (cons ?3 olddef-1))) ⇒ (keymap (49 . olddef-1) (50 . olddef-2) (51 . olddef-1))
(substitute-key-definition 'olddef-1 'newdef map) ⇒ nil
map ⇒ (keymap (49 . newdef) (50 . olddef-2) (51 . newdef))
This function changes the contents of the full keymap keymap by
self-insert-command to the command
(see Remapping Commands). This has the effect of undefining all
printing characters, thus making ordinary insertion of text impossible.
If nodigits is
digits to run
digit-argument, and - to run
negative-argument. Otherwise it makes them undefined like the
rest of the printing characters.
suppress-keymap function does not make it impossible to
modify a buffer, as it does not suppress commands such as
quoted-insert. To prevent any modification of a buffer, make
it read-only (see Read Only Buffers).
Since this function modifies keymap, you would normally use it
on a newly created keymap. Operating on an existing keymap
that is used for some other purpose is likely to cause trouble; for
global-map would make it impossible to use
most of Emacs.
This function can be used to initialize the local keymap of a major
mode for which insertion of text is not desirable. But usually such a
mode should be derived from
special-mode (see Basic Major Modes); then its keymap will automatically inherit from
special-mode-map, which is already suppressed. Here is how
special-mode-map is defined:
(defvar special-mode-map (let ((map (make-sparse-keymap))) (suppress-keymap map) (define-key map "q" 'quit-window) … map))