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zh-CN :Xmodmap

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

xmodmap is not directly related to XKB, it uses different (pre-XKB) ideas on how keycodes are processed within Xorg. Generally it is not recommended to use xmodmap, except maybe for the simplest tasks. See X KeyBoard extension if you have special demands on layout configuration.


On a Linux system using Xorg, there are two types of keyboard values: keycodes and keysyms.

The keycode is the numeric representation received by the Linux kernel when a keyboard key or a mouse button is pressed.
The keysym is the value assigned to the keycode. For example, when you press the A key on the keyboard, it generates keycode 73. Keycode 73 is mapped to the keysym 0×61 which corresponds to the letter a 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. The command xmodmap can be used to show/modify that key table.


In order to use xmodmap, you need to install the xorg-xmodmap package from the official repositories.

Optionally, install also xkeycaps which provides 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 57 is mapped to the lowercase n, while the uppercase N is mapped to keycode 57 plus Shift.

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

  1. Key
  2. Shift+Key
  3. mode_switch+Key
  4. mode_switch+Shift+Key
  5. AltGr+Key
  6. AltGr+Shift+Key

Not all keysyms have to be set, but if you want to assign a latter keysym without assigning earlier ones, set them to NoSymbol.

You can check which keycode corresponds to a key on your keyboard with the xev utility, see Extra Keyboard Keys#In Xorg for details.

Tip: There are predefined descriptive keysyms for multimedia keys, e.g. XF86AudioMute or XF86Mail. These keysyms can be found in /usr/include/X11/XF86keysym.h. Many multimedia programs are designed to work with these keysyms out-of-the-box, without the need to configure any third-party application.

Custom table

You can create your own map and store it in a configuration file in your home directory (i.e. ~/.Xmodmap):

xmodmap -pke > ~/.Xmodmap

Make the desired changes to ~/.Xmodmap and then test the new configuration with:

xmodmap ~/.Xmodmap

Activate your custom table

If you are using GDM, XDM or KDM, there is no need to source your ~/.Xmodmap manually as these display managers source that file if it is present, whereas startx does not. Therefore, to activate your custom table when starting Xorg, add the following:

if [ -s ~/.Xmodmap ]; then
    xmodmap ~/.Xmodmap

Alternatively, edit the global startup script /etc/X11/xinit/xinitrc.

Test changes

You can also make temporary changes for the current session. For example:

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

Special keys/signals

You can also also edit the keys: Shift, Ctrl, Alt and Super (there always exists a left and a right one (Alt_R=AltGr)).

For example this can be useful if your right Control key is not working like your left one but you would like it to.

At first you have to delete/clear the signals that should be edited. In the beginning of your ~/.Xmodmap:

!clear Shift
!clear Lock
clear Control
!clear Mod1
!clear Mod2
!clear Mod3
clear Mod4
!clear Mod5
keycode   8 =

Remember, ! is a comment so only Control and Mod4 (Standard: Super_L Super_R) get cleared.

Write the new signals at the end of ~/.Xmodmap

keycode 255 =
!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 Super keys have now been exchanged with the Ctrl keys.

If you get the following error message X Error of failed request: BadValue (integer parameter out of range for operation) it means the key you are trying to add is already in another modifier, so remove it using "remove MODIFIERNAME = KEYSYMNAME". Running xmodmap gives you a list of modifiers and keys that are assigned to them.

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 ~/.Xmodmap.

Open ~/.Xmodmap and append the following line to the file:

pointer = 1 2 3 5 4 7 6 8 9 10 11 12

Note how the 4 and 5 have been reversed.

Then update xmodmap:

xmodmap ~/.Xmodmap

To return to regular scrolling simply reverse the order of the 4 and 5 or delete the line altogether. For more information check Peter Hutterer's post, Natural scrolling in the synaptics driver, or the Reverse scrolling direction ala Mac OS X Lion? forum thread.



keycode  24 = a A aacute Aacute ae AE ae
keycode  26 = e E eacute Eacute EuroSign cent EuroSign
keycode  30 = u U uacute Uacute downarrow uparrow downarrow
keycode  31 = i I iacute Iacute rightarrow idotless rightarrow
keycode  32 = o O oacute Oacute oslash Oslash oslash
keycode  57 = n N ntilde Ntilde n N n
keycode  58 = comma question comma questiondown dead_acute dead_doubleacute dead_acute
keycode  61 = exclam section exclamdown section dead_belowdot dead_abovedot dead_belowdot
!Maps the Mode key to the Alt key
keycode 64 = Mode_switch

Turn CapsLock into Control, and LeftControl into Hyper

Laptop users may find that using CapsLock as Control is so usefull.

clear control 
clear lock 
clear mod1
clear mod3
keycode  37 = Hyper_L
keycode  66 = Control_L
add control = Control_L Control_R
add    mod1 = Alt_L Alt_R Meta_L
add    mod3 = Hyper_L

See also