Difference between revisions of "Keyboard configuration in Xorg"

Revision as of 16:52, 31 October 2013

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Xorg uses the X KeyBoard extension (XKB) to manage keyboard layouts. Alternatively, xmodmap can be used to access the internal keymap table directly. Generally it is not recommended to use xmodmap, except perhaps for the simplest tasks.

This article describes low-level configuration using XKB which is effective in most cases, but some desktop environments like GNOME override it with its own settings.

Viewing keyboard settings

You can use the following command to see the actual XKB settings:

$ setxkbmap -print -verbose 10

Setting verbose level to 10
locale is C
Applied rules from evdev:
model:      evdev
layout:     us
options:    terminate:ctrl_alt_bksp
Trying to build keymap using the following components:
keycodes:   evdev+aliases(qwerty)
types:      complete
compat:     complete
symbols:    pc+us+inet(evdev)+terminate(ctrl_alt_bksp)
geometry:   pc(pc104)
xkb_keymap {
        xkb_keycodes  { include "evdev+aliases(qwerty)" };
        xkb_types     { include "complete"      };
        xkb_compat    { include "complete"      };
        xkb_symbols   { include "pc+us+inet(evdev)+terminate(ctrl_alt_bksp)"    };
        xkb_geometry  { include "pc(pc104)"     };
};

Setting keyboard layout

Keyboard layout in Xorg can be set in multiple ways. Here is an explanation of used options:

• XkbModel selects the keyboard model. This has an influence only for some extra keys your keyboard might have. The safe fallback are pc104 or pc105. But for instance laptops usually have some extra keys, and sometimes you can make them work by simply setting a proper model.
• XkbLayout selects the keyboard layout. Multiple layouts may be specified in a comma-separated list, e.g. if you want to quickly switch between layouts.
• XkbVariant selects a specific layout variant. For instance, the default sk variant is qwertz, but you can manually specify qwerty etc.

Warning: You must specify as many variants as the number of specified layouts. If you want the default variant, specify an empty string as the variant (the comma must stay). For example, to have the default us layout as primary and the dvorak variant of us layout as secondary, specify us,us as XkbLayout and ,dvorak as XkbVariant.

• XkbOptions contains some extra options. Used for specifying layout switching, notification LED, compose mode etc.

The layout name is usually a 2-letter country code. To see a full list of keyboard models, layouts, variants and options, along with a short description, open /usr/share/X11/xkb/rules/base.lst. Alternatively, you may use one of the following commands to see a list without a description:

• localectl list-x11-keymap-models
• localectl list-x11-keymap-layouts
• localectl list-x11-keymap-variants [layout]
• localectl list-x11-keymap-options

Examples in the following subsections will have the same effect, they will set pc104 model, cz as primary layout, us as secondary layout, dvorak variant for us layout and the Alt+Shift combination for switching between layouts.

Using setxkbmap

The tool setxkbmap sets the keyboard layout for an active X server and the setting is persistent only until the session ends, but you can use xinitrc to make it persistent across reboots. It is useful to override system-wide configuration specified by X configuration files.

The usage is as follows:

$ setxkbmap [-model xkb_model] [-layout xkb_layout] [-variant xkb_variant] [-option xkb_options]

It is not necessary to specify all options, e.g. you can change just a layout:

$ setxkbmap -layout xkb_layout

See man 1 setxkbmap for a full list of command line arguments.

For example:

$ setxkbmap -model pc104 -layout cz,us -variant ,dvorak -option grp:alt_shift_toggle

Using X configuration files

The syntax of X configuration files is explained in Xorg#Configuration. This method creates system-wide configuration which is persistent across reboots.

Here is an example:

/etc/X11/xorg.conf.d/10-keyboard.conf

Section "InputClass"
        Identifier "system-keyboard"
        MatchIsKeyboard "on"
        Option "XkbLayout" "cz,us"
        Option "XkbModel" "pc104"
        Option "XkbVariant" ",dvorak"
        Option "XkbOptions" "grp:alt_shift_toggle"
EndSection

Using localectl

For convenience, the tool localectl may be used instead of manual editing of X configuration file. It will save the configuration in /etc/X11/xorg.conf.d/00-keyboard.conf, this file should not be manually edited, because localectl will overwrite the changes on next start.

The usage is as follows:

$ localectl set-x11-keymap layout [model] [variant] [options]

The following command will create a file /etc/X11/xorg.conf.d/00-keyboard.conf with pretty much the same content as the example above:

$ localectl set-x11-keymap cz,us pc104 ,dvorak grp:alt_shift_toggle

Frequently used XKB options

Switching between keyboard layouts

To be able to easily switch keyboard layouts, first specify multiple layouts between which you want to switch (the first one is the default). Then specify a key (or key combination), which will be used for switching. For example, to switch between a US and a Swedish layout using the CapsLock key, use us,se as an argument of XkbLayout and grp:caps_toggle as an argument of XkbOptions.

You can use other key combinations than CapsLock, they are listed in /usr/share/X11/xkb/rules/base.lst, start with grp: and end with _toggle. To get the full list of available options, run the following command:

$ grep "grp:.*_toggle" /usr/share/X11/xkb/rules/base.lst

Terminating Xorg with Ctrl+Alt+Backspace

By default, the key combination Ctrl+Alt+Backspace is disabled. You can enable it by passing terminate:ctrl_alt_bksp to XkbOptions.

Swapping Caps Lock with Left Control

To swap Caps Lock with Left Control you can add ctrl:swapcaps,ctrl:nocaps to XkbOptions.

Enabling mouse keys

Mouse keys is now disabled by default and has to be manually enabled by passing keypad:pointerkeys to XkbOptions. This will make the Shift+NumLock shortcut toggle mouse keys.

Configuring compose key

The compose key, when pressed in sequence with other keys, produces a unicode character. For example, in most configurations pressing compose_key ' e produces é. This is especially useful if you need to type in a different language then the one for which the keyboard layout was designed (such as typing in French, Italian and German on an American keyboard).

For example, to make the right Alt key a compose key, pass compose:ralt to XkbOptions.

You can use other keys as compose keys, they are listed in /usr/share/X11/xkb/rules/base.lst and start with compose:. To get the full list of available options, run the following command:

$ grep "compose:" /usr/share/X11/xkb/rules/base.lst

Key combinations

The default combinations for the compose keys depend on the locale and are stored in /usr/share/X11/locale/used_locale/Compose, where used_locale is for example en_US.UTF-8.

You can define your own compose key combinations by copying the default file to ~/.XCompose and editing it. The compose key works with any of the thousands of valid Unicode characters, including those outside the Basic Multilingual Plane.

However, GTK does not use XIM by default and therefore does not follow ~/.XCompose keys. This can be fixed by forcing GTK to use XIM by adding export GTK_IM_MODULE=xim and/or export XMODIFIERS="@im=none" to ~/.xprofile.

Other settings

Adjusting typematic delay and rate

The typematic delay indicates the amount of time (typically in miliseconds) a key needs to be pressed in order for the repeating process to begin. After the repeating process has been triggered, the character will be repeated with a certain frequency (usually given in Hz) specified by the typematic rate. These values can be changed using the xset command:

$ xset r rate delay [rate]

For example to set a typematic delay to 200ms and a typematic rate to 30Hz, use the following command (use xinitrc to make it permanent):

$ xset r rate 200 30

Issuing the command without specifying the delay and rate will reset the typematic values to their respective defaults; a delay of 660ms and a rate of 25Hz:

$ xset r rate