How to make CapsLock-key have Ctrl-key functionality in X11

in ~/.xsession:

    xmodmap -e 'remove Control = Control_L'
    xmodmap -e 'remove Control = Control_R'
    xmodmap -e 'clear Lock'
    xmodmap -e 'keysym Caps_Lock = Control_R'
    xmodmap -e 'keysym Control_L = Caps_Lock'
    xmodmap -e 'add Control = Control_L'
    xmodmap -e 'add Control = Control_R'
    xmodmap -e 'keysym Caps_Lock = Print'

Enjoy.