nocaps.sh

#!/bin/sh

# http://gist.github.com/500229.txt
if [ "$TERM" = "linux" ]; then
    # NOTE: dumpkeys & loadkeys command enable superuser only
    dumpkeys | sed -e 's/keycode  58 = Caps_Lock/keycode  58 = Control/' | loadkeys
    # echo 'keycode  58 = Control' | loadkeys
else
    # Make CapsLock an additional Ctrl.
    setxkbmap -option ctrl:nocaps
fi

# or
# xmodmap -e 'remove Lock = Caps_Lock'
# xmodmap -e 'add Control = Caps_Lock'
# xmodmap -e 'keysym Caps_Lock = Control_L'