I wanted to stop the screen on my Mythbuntu MythTV system from being blanked after a period of inactivity. (This is to improve the usability of the system – otherwise when someone is faced with a blank TV screen it’s difficult enough trying to figure out whether it’s because the TV is turned off, or the Mythbox is turned off, or the receiver is set to the wrong input, etc. I didn’t want to have to include an extra troubleshooting step of ‘waggle the mouse to make sure that Ubuntu hasn’t blanked the screen’ for when members of the household are having problems.)
I thought this would be easy, but it turned out to be more fiddly than I was expecting. You can go to Applications -> Settings -> Screensaver, but the maximum inactivity timeout you can set there is 720 minutes, or 12 hours, and I wanted a longer inactivity period than that. And if you go to Applications -> Settings -> Session and Startup -> Application Autostart and disable Screensaver then the screen still goes blank, this time after about 10 minutes of inactivity.
The solution I found (based on a response to a question at http://ubuntuforums.org/showthread.php?t=2141848 ) is to disable Screensaver and then create a file called 10-disable-dpms.conf in /usr/share/X11/xorg.conf.d which contains the following:
Section "ServerFlags" Option "BlankTime" "0" Option "StandbyTime" "0" Option "SuspendTime" "0" Option "OffTime" "0" EndSection
(The person who had contributed the response created the file in the /etc/X11/xorg.conf.d directory. My system already had a directory /usr/share/X11/xorg.conf.d so I created the file there. So the correct place to put it may vary from system to system.)
Not terribly intuitive – but at least this works – finally, the system no longer blanks the screen!