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.
keymap-local-set functions are
convenient interfaces for these operations (see Commands for Binding Keys). You can also use
keymap-set, 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).
The functions below signal an error if keymap is not a keymap, or if key is not a valid key.
key is a string representing a single key or a series of key
strokes, and must satisfy
key-valid-p. Key strokes are
separated by a single space character.
Each key stroke is either a single character, or the name of an event, surrounded by angle brackets. In addition, any key stroke may be preceded by one or more modifier keys. Finally, a limited number of characters have a special shorthand syntax. Here’s some example key sequences:
The key f.
A three key sequence of the keys S, o and m.
A two key sequence of the keys c with the control modifier and then the key o
The key named left with the hyper modifier.
The return key with a meta modifier.
The space key with both the control and meta modifiers.
The only keys that have a special shorthand syntax are NUL, RET, TAB, LFD, ESC, SPC and DEL.
The modifiers have to be specified in alphabetical order: ‘A-C-H-M-S-s’, which is ‘Alt-Control-Hyper-Meta-Shift-super’.
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
keymap-set 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
keymap-set 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 function is the inverse of
keymap-set, it unsets the
binding for key in keymap, which is the same as setting
the binding to
nil. In order to instead remove the binding
completely, specify remove as non-
nil. This only makes a
difference if keymap has a parent keymap: if you just unset a key
in a child map, it will still shadow the same key in the parent
keymap; using remove instead will allow the key in the parent keymap
to be used.
keymap-unset with remove non-
intended for users to put in their init file; Emacs packages should
avoid using it if possible, since they have complete control over
their own keymaps anyway, and they should not be altering other
This example creates a sparse keymap and makes a number of bindings in it:
(setq map (make-sparse-keymap)) ⇒ (keymap)
(keymap-set map "C-f" 'forward-char) ⇒ forward-char
map ⇒ (keymap (6 . forward-char))
;; Build sparse submap for C-x and bind f in that. (keymap-set map "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. (keymap-set map "C-p" ctl-x-map) ;;
ctl-x-map⇒ [nil … find-file … backward-kill-sentence]
;; Bind C-f to
ctl-x-map. (keymap-set map "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.
keymap-set is the general work horse for defining a key in a
keymap. When writing modes, however, you frequently have to bind a
large number of keys at once, and using
keymap-set on them all
can be tedious and error-prone. Instead you can use
define-keymap, which creates a keymap and binds a number of
keys. See Creating Keymaps, for details.
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) (keymap-set map "q" 'quit-window) … map))