It turns out the solution is very simple. The xset command is the X server preferences command. It has a simple command to turn off the monitor:

$ xset dpms force off

 

and to turn the monitor back on:

$ xset dpms force on

 

You can also check the status of the X server settings by using:

$ xset -q

 

来源： How To Turn Off Your Monitor Via Command Line in Ubuntu | systemBash