How to set the keymap for keyboards that are plugged in later?

Question

I have configured my keyboard layout by adding a call to setxkbmap to my .xinitrc. This works for my laptop's internal keyboard and for any external keyboard that is plugged in when the X server starts. If I plug in an external keyboard later, it uses the default US keymap.

How can I make sure that any keyboard that I plug in has my preferred layout?

Answer 1

As Gilles commented on Dominik R's answer yesterday, the udev approach only works for the root user and doesn't work well as a general, unprivileged solution. I'd suggest considering inputplug(1) by Andrew Shadura available in Debian as the package inputplug as well as at the project site.

inputplug(1) is a rather straightforward as a XINPUT event loop listener which will invoke a script with decoded event parameters as arguments. Since you're using .xinitrc, I imagine you're using a modest window manager / environment and a background listener of this sort should be pretty straightforward for you.

Another possibility is using udev in a less traditional way by writing a script parsing the output from "udevadm monitor" and invoking setxkbmap upon recognizing a matching device being connnected.

Good Luck!

Answer 2

inputplug, suggested by etherfish five years ago, is an excellent answer, but the answer was missing a complete example. So here is what I use in my .xinitrc to run setxkbmap exactly once in the beginning, and another time every time a new keyboard is plugged in:

{ echo "XIDeviceEnabled XISlaveKeyboard"; inputplug -d -c /bin/echo; } |
while read event
do
        case $event in
        XIDeviceEnabled*XISlaveKeyboard*)
                setxkbmap -option grp:switch,grp:shift_toggle,grp_led:scroll us,il ,lyx
                setxkbmap -option caps:none
                ;;
        esac
done &

The inputplug -d -c /bin/echo echos a message like

XIDeviceEnabled 11 XISlaveKeyboard Logitech K270

every time a keyboard is plugged in, and the while loop finds such messages and causes the relevant setxkbmap commands to run (in my example, I set a Hebrew keyboard mapping, and remove the Caps Lock feature which I hate). The extra echo "XIDeviceEnabled XISlaveKeyboard" in the beginning causes the loop to also find a "new keyboard" exactly once in the beginning. inputplug also has a "-0" option to print existing keyboards on startup, but this will usually print multiple keyboards and cause the setxkbmap to be needlessly run multiple times on startup.