https://raspberrypi.stackexchange.com/questions/24161/change-keyboard-layout-in-console

example:

$ cat /etc/default/keyboard

# KEYBOARD CONFIGURATION FILE

# Consult the keyboard(5) manual page.

XKBMODEL="pc105"
XKBLAYOUT="us,ru"
XKBVARIANT=","
XKBOPTIONS="grp:caps_toggle,grp:lwin_switch,compose:ralt,terminate:ctrl_alt_bks$

BACKSPACE="guess"