I'd like to find a way to tell, from a shell script, if the (X windows) 
screen is blanked on my machine.  In particular, I'd like to avoid 
displaying new background images on my laptop if the screen is blanked 
(and if the machine is on battery, but I know how to test that).  

If it matters, I'm running Xorg.

		--Steven M. Bellovin, http://www.cs.columbia.edu/~smb