The XKB Configuration Guide : Selecting XKB Configuration
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Next: Direct XKB Configuration

2. Selecting XKB Configuration

The easiest and the most natural way to specify a keyboard mapping is to use the rules component. As its name suggests it describes a number of general rules to combine all bits and pieces into a valid and useful keyboard mapping. All you need to do is to select a suitable rules file and then to feed it with a few parameters that will adjust the keyboard behaviour to fulfill your needs.

The parameters are:

The proper rules file depends on your vendor. In reality, the commonest file of rules is xorg. For each rules file there is a description file named <vendor-rules>.lst, for instance xorg.lst which is located in the xkb configuration subdirectory rules (for example /etc/X11/xkb/rules).

2.1. Basic Configuration

Let's say you want to configure a PC-style American keyboard with 104 keys as described in xorg.lst. This can be done by simply writing several lines from below to your xorg.conf configuration file (previously known as /etc/X11/XF86Config-4 or /etc/X11/XF86Config): 

Section "InputDevice"
    Identifier "Keyboard1"
    Driver "kbd"

    Option "XkbModel" "pc104"
    Option "XkbLayout" "us"
    Option "XKbOptions" ""
EndSection
The values of XkbModel and XkbLayout are really not surprising. The XkbOptions has been explicitly set to the empty set of parameters. The XkbVariant option has been left out. That means the default variant named basic is loaded.

Of course, this can be also done at runtime using the utility setxkbmap. The shell command loading the same keyboard mapping would look like: 

setxkbmap -rules xorg -model pc104 -layout us -option ""
The configuration and the shell command would be very analogous for most other layouts (internationalized mappings).

2.2. Advanced Configuration

You can use multi-layouts xkb configuration. What does it mean? Basically it allows to load up to four different keyboard layouts at a time. Each such layout would reside in its own group. The groups (unlike complete keyboard remapping) can be switched very fast from one to another by a combination of keys.

Let's say you want to configure your new Logitech cordless desktop keyboard, you intend to use three different layouts at the same time - us, czech and german (in this order), and that you are used to Alt-Shift combination for switching among them.

Then the configuration snippet could look like this: 

Section "InputDevice"
    Identifier "Keyboard1"
    Driver "kbd"

    Option "XkbModel" "logicordless"
    Option "XkbLayout" "us,cz,de"
    Option "XKbOptions" "grp:alt_shift_toggle"
EndSection
Of course, this can be also done at runtime using the utility setxkbmap. The shell command loading the same keyboard mapping would look like: 
setxkbmap -rules xorg -model logicordless -layout "us,cz,de" \
         -option "grp:alt_shift_toggle"

2.3. Even More Advanced Configuration

Okay, let's say you are more demanding. You do like the example above but you want it to change a bit. Let's imagine you want the czech keyboard mapping to use another variant but basic. The configuration snippet then changes into: 

Section "InputDevice"
    Identifier "Keyboard1"
    Driver "kbd"

    Option "XkbModel" "logicordless"
    Option "XkbLayout" "us,cz,de"
    Option "XkbVariant" ",bksl,"
    Option "XKbOptions" "grp:alt_shift_toggle"
EndSection
That seems tricky but it is not. The logic for settings of variants is the same as for layouts, that means the first and the third variant settings are left out (set to basic), the second is set to bksl (a special variant with an enhanced definition of the backslash key).

Analogously, the loading runtime will change to: 

setxkbmap -rules xorg -model logicordless -layout "us,cz,de" \
         -variant ",bksl," -option "grp:alt_shift_toggle"

2.4. Basic Global Options

See rules/*.lst files.

The XKB Configuration Guide : Selecting XKB Configuration
Previous: Overview
Next: Direct XKB Configuration