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 how to specify a keyboard mapping is tu use rules component. As its name suggests it describes a number of general rules how 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 xfree86. For each rules file there is a description file named <vendor-rules>.lst, for instance xfree86.lst which is located in xkb configuration subdirectory rules (for example /etc/X11/xkb/rules).

2.1. Basic Configuration

Let's say you want to configure a PC style America keyboard with 104 keys as described in xfree86.lst. It can be done by simply writing several lines from below to you XFree86 configuration file (often found as /etc/X11/XF86Config-4 or /etc/X11/XF86Config): 

Section "InputDevice"
    Identifier "Keyboard1"
    Driver "Keyboard"

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

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

setxkbmap -rules xfree86 -model pc104 -layout us -option ""
The configuration and the shell command would be very analogical for most other layouts (internationalized mappings).

2.2. Advanced Configuration

Since XFree86 4.3.x 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 "Keyboard"

    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 utility setxkbmap. Shell command loading the same keyboard mapping would look like: 
setxkmap -rules xfree86 -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 "Keyboard"

    Option "XkbModel" "logicordless"
    Option "XkbLayout" "us,cz,de"
    Option "XkbVariant" ",bksl,"
    Option "XKbOptions" "grp:alt_shift_toggle"
EndSection
That's 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).

Analogically, the loading runtime will change to: 

setxkmap -rules xfree86 -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