xmodmap

xmodmap is a utility for modifying keymaps and pointer button mappings in Xorg.

xmodmap is not directly related to X keyboard extension (XKB), as it uses different (pre-XKB) ideas on how keycodes are processed within X. Generally, it is only recommended for the simplest tasks. See X keyboard extension for advanced layout configuration.

Note:

xmodmap settings are reset by setxkbmap, which not only alters the alphanumeric keys to the values given in the map, but also resets all other keys to the startup default (see LQWiki:Configuring keyboards).
Due to a limitation of Xorg, xmodmap settings are not applied to hotplugged devices automatically. If a keyboard is added to a system after a custom table has been applied, the custom table will have to be applied again.

Introduction

There are two types of keyboard values in Xorg: keycodes and keysyms.

keycode: The keycode is the numeric representation received by the kernel when a key or a mouse button is pressed.
keysym: The keysym is the value assigned to the keycode. For example, pressing generates the , which is mapped to the , which matches in the ASCII table.; The keysyms are managed by Xorg in a table of keycodes defining the keycode-keysym relations, which is called the keymap table. This can be shown by running .

Installation

xmodmap can be installed through the package.

Optionally, install xkeycaps, which is a graphical front-end to xmodmap.

Keymap table

Print the current keymap table formatted into expressions:

$ xmodmap -pke

[...]
keycode  57 = n N
[...]

Each keycode is followed by the keysym it is mapped to. The above example indicates that the keycode is mapped to the lowercase , while the uppercase is mapped to keycode plus .

Each keysym column in the table corresponds to a particular combination of modifier keys:

ISO_Level3_Shift+Key

Not all keysyms have to be set, but to assign only a latter keysym, use the value.

To see which keycode corresponds to a key, see Keyboard input#Identifying keycodes in Xorg for details on the xev utility which will output relevant keycode/keysym information about a key when you press it.

Note that xmodmap is influenced by xkbd settings, so all eight keysym are available for the US(intl) xkbd layout but not for the default US (it is missing the ralt_switch symbol defined in level3). To have all 8 keysyms available you should configure the (intl) variant of the keyboard. Using US layout as an example, $ setxkbmap -layout 'us(intl)' before calling xmodmap to test your changes in the current X session. To permanently make this change, edit the xorg configuration or your .xprofile or .xinitrc file. See Xorg/Keyboard configuration#Setting keyboard layout for a full explanation.

Custom table

To create a key map (i.e. ):

$ xmodmap -pke > ~/.Xmodmap

To test the changes:

$ xmodmap ~/.Xmodmap

Activating the custom table

With GDM, XDM or LightDM there is no need to source . For startx, use:

Alternatively, edit the global startup script .

Test changes

To make temporary changes:

$ xmodmap -e "keycode 46 = l L l L lstroke Lstroke lstroke"
$ xmodmap -e "keysym a = e E"

Modifier keys

xmodmap can also be used to override modifier keys, e.g. to swap and (the Windows key).

Print the current modifier table verbosely (full sample):

Finding the keysym column modifier keys

ISO_Level3_Shift: The AltGr key on non-US keyboards calls modifier ISO_Level3_Shift. (On US keyboards, the right-alt has the same function as the left-alt , which makes setting the layout as US international preferable. See #Keymap table.)
Mode_switch: The Mode_switch modifier may be mapped by default to a key that is not on your keyboard.

Reassigning modifiers to keys on your keyboard

Note: xmodmap is case-sensitive. Using incorrect case, such as Mode_Switch instead of the correct Mode_switch will cause errors.

Before assignment, the modifier keys need to be cleared. This applies to both modifiers you intend to assign and modifiers on keys that you intend to use. For example, if you intend to assign to your A key and to your NumLock key, you need to first clear the modifiers for both and , then assign the keysyms, and finally add back the modifiers.

is a comment, so only the modifiers  and Mod4 get cleared in the following example. Then the keysyms , ,  and  are assigned to the opposite modifier. Assigning both left and right to the same modifier means that both keys are treated the same way.

~/.Xmodmap

[...]
!clear Shift
!clear Lock
clear Control
!clear Mod1
!clear Mod2
!clear Mod3
clear Mod4
!clear Mod5
!add Shift   = Shift_L Shift_R
!add Lock    = Caps_Lock
add Control = Super_L Super_R
!add Mod1    = Alt_L Alt_R
!add Mod2    = Mode_switch
!add Mod3    =
add Mod4    = Control_L Control_R
!add Mod5    =

The following example modifies to , and to :

Compose key

A compose key serves to create special characters and symbols that may not be directly accessible on the keyboard. This is especially useful for typing accented letters from non-English languages. For example, pressing Compose in succession will produce é. Some characters require more than 2 keys to be pressed after Compose. Usually a modifier key of choice is mapped to Compose. The compose key can be set in the GUI settings of most desktop environments, but these options will not work if a custom key map table is used as described in this article. To set the compose key using , use the identifier. For example, to map the right alt key () to the compose key:

The keycode number could vary based on keyboard models.

Reverse scrolling

The natural scrolling feature available in OS X Lion (mimicking smartphone or tablet scrolling) can be replicated with xmodmap. Since the synaptics driver uses the buttons 4/5/6/7 for up/down/left/right scrolling, you simply need to swap the order of how the buttons are declared in :

Then update xmodmap:

$ xmodmap ~/.Xmodmap

Swapping mouse buttons

The left, middle and right mouse buttons correspond to buttons 1,2 and 3 respectively in the synaptics driver. To swap left and right mouse buttons, again simply reverse the order in which they are listed in your :

This should suffice for a simple mouse setup. Again, update xmodmap:

$ xmodmap ~/.Xmodmap

Templates

Turn CapsLock into Control

Simplest example of changing into .

~/.Xmodmap

clear lock
clear control
keycode 66 = Control_L
add control = Control_L Control_R

Turn CapsLock into Control, and LeftControl into Hyper

Laptop users may prefer having as . The key can be used as a modifier (an additional modifier for emacs, openbox or i3).

Turn Super_R into Hyper_R

Users who wish to have a key on full keyboard layout may wish to use the Right key as .

Switch every number key N with Shift-N and vice-versa, for Croatian layout

Should work fine for layouts similar to Croatian as well.

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