CODE EXAMPLE FOR SHELL

arch console set default keyboard layout

# localectl set-keymap --no-convert <keymap>
keymap is a string such as en, fr_FR, en_US, fr, ...
For example (as root) : localectl set-keymap --no-convert fr

You can also edit /etc/vconsole.conf as such but 
    you will need to restart your computer :
KEYMAP=fr