GNU Emacs

49.3.6 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 initialization file by writing Lisp code. See The Emacs Initialization File, for a description of the initialization file.

There are several ways to write a key binding using Lisp. The simplest is to use the kbd function, which converts a textual representation of a key sequence—similar to how we have written key sequences in this manual—into a form that can be passed as an argument to global-set-key. For example, here’s how to bind C-z to the shell command (see Interactive Subshell):

(global-set-key (kbd "C-z") 'shell)

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 as a variable. This probably causes an error; it certainly isn’t what you want.

Here are some additional examples, including binding function keys and mouse events:

(global-set-key (kbd "C-c y") 'clipboard-yank)
(global-set-key (kbd "C-M-q") 'query-replace)
(global-set-key (kbd "<f5>") 'flyspell-mode)
(global-set-key (kbd "C-<f5>") 'display-line-numbers-mode)
(global-set-key (kbd "C-<right>") 'forward-sentence)
(global-set-key (kbd "<mouse-2>") 'mouse-save-then-kill)

Instead of using kbd, you can use a Lisp string or vector to specify the key sequence. Using a string is simpler, but only works for ASCII characters and Meta-modified ASCII characters. For example, here’s how to bind C-x M-l to make-symbolic-link (see Copying, Naming and Renaming Files):

(global-set-key "\C-x\M-l" 'make-symbolic-link)

To bind a key sequence including TAB, RET, ESC, or DEL, the string should contain the Emacs Lisp escape sequence ‘ \t’, ‘ \r’, ‘ \e’, or ‘ \d’ respectively. Here is an example which binds C-x TAB to indent-rigidly (see Indentation):

(global-set-key "\C-x\t" 'indent-rigidly)

When the key sequence includes function keys or mouse button events, or non-ASCII characters such as C-= or H-a, you can use a vector to specify the key sequence. Each element in the vector stands for an input event; the elements are separated by spaces and surrounded by a pair of square brackets. 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. Function keys are represented by symbols (see Rebinding Function Keys); simply write the symbol’s name, with no other delimiters or punctuation. Here are some examples:

(global-set-key [?\C-=] 'make-symbolic-link)
(global-set-key [?\M-\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:

(global-set-key [?\C-z ?\M-l] 'make-symbolic-link)

Language and coding systems may cause problems with key bindings for non-ASCII characters. See Non-ASCII Characters in Init Files.

As described in Local Keymaps, major modes and minor modes can define local keymaps. These keymaps are constructed when the mode is loaded for the first time in a session. The function define-key can be used to make changes in a specific keymap. This function can also unset keys, when passed nil as the binding.

Since a mode’s keymaps are not constructed until it has been loaded, you must delay running code which modifies them, e.g., by putting it on a mode hook (see Hooks). For example, Texinfo mode runs the hook texinfo-mode-hook. Here’s how you can use the hook to add local bindings for C-c n and C-c p, and remove the one for C-c C-x x in Texinfo mode:

(add-hook 'texinfo-mode-hook
          (lambda ()
            (define-key texinfo-mode-map "\C-cp"
            (define-key texinfo-mode-map "\C-cn"
            (define-key texinfo-mode-map "\C-c\C-xx" nil)