I am trying to use the radeontool to be able to turn off/on my backlight on my laptop. I run the command radeontool light off as root and it works, but when i run it under a normal user, i get this error:
can't open /dev/mem
Are you root?

I've changed /dev/mem, but i still can't get it to run.
diegoa@ibm-1500:~/Programs/radeontool-1.5> ls -la /dev/mem
crwxrwxrwx 1 diegoa kmem 1, 1 2005-03-19 13:36 /dev/mem

I have a perl file of how somebody else is using the radeontool command to turn off the light when the screensaver comes on. I can post that up if it will help. Thanks

I would think that 'xset dpms force off' would be sufficient.