xset
- controls a variety of X settings and preferences, like mouse, keyboard, bell, display, fonts.
For example, to switch the display off, even if the keyboard doesn't have such a key:
xset dpms force off
It's handy to assign an alias to the command:
alias xs='xset dpms force off'
to switch display off from terminal with xs
command. Display wakes up by any input from keyboard, mouse, touchpad, etc.