xrandr

How to use external display?

xrandr -q
xrandr --output VGA --auto

Turn off

xrandr --output VGA --off 

http://www.thinkwiki.org/wiki/Xorg_RandR_1.2

http://academic.meganebu.com/~debug_ito/index.php?Ubuntu%2Fxrandr%A4%C7%B3%B0%C9%F4%A5%E2%A5%CB%A5%BF%BD%D0%CE%CF