57.4.7 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) 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. 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.)

See section Rebinding Keys in Your Init File, 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)

Many keyboards have a “numeric keypad” on the right hand side. The numeric keys in the keypad double up as cursor motion keys, toggled by a key labeled ‘Num Lock’. By default, Emacs translates these keys to the corresponding keys in the main keyboard. For example, when ‘Num Lock’ is on, the key labeled ‘8’ on the numeric keypad produces kp-8, which is translated to 8; when ‘Num Lock’ is off, the same key produces kp-up, which is translated to <UP>. If you rebind a key such as 8 or <UP>, it affects the equivalent keypad key too. However, if you rebind a ‘kp-’ key directly, that won't affect its non-keypad equivalent.

Emacs provides a convenient method for binding the numeric keypad keys, using the variables keypad-setup, keypad-numlock-setup, keypad-shifted-setup, and keypad-numlock-shifted-setup. These can be found in the ‘keyboard’ customization group (see section Easy Customization Interface). You can rebind the keys to perform other tasks, such as issuing numeric prefix arguments.