FROM:http://askubuntu.com/questions/63681/how-can-i-make-xrandr-customization-permanent
I got this to WORK
Modify
/etc/lightdm/lightdm.confto add the following options:
display-setup-script > calls your mycustomloginvideo.sh before the login screen appears
session-setup-script > calls your mycustomdesktopvideo.sh before the user desktop session starts
[SeatDefaults]
greeter-session=unity-greeter
user-session=ubuntu
# for your login screen, e.g. LightDM (Ubuntu 11.10) or GDM (11.04 or earlier)
display-setup-script=/usr/share/mycustomloginvideo.sh
# for your desktop session
session-setup-script=/usr/share/mycustomdesktopvideo.sh
You may have “arandr” gui tool generate the above sh script, picking parameters from your current session’s X configuration.
Make sure that your shell script is executable:
chmod a+x /usr/share/mycustom*video.sh
and you can test that it works (i.e. that you don’t have any typos or configuration errors in your xrandr command) just by running it in a terminal:
/usr/share/mycustomdesktopvideo.sh
If the login script doesn’t work for any reason, your machine might not complete the boot process to the login screen. If the desktop script fails, you might not get a desktop after logging in. If you are setting an external monitor, these scripts will fail when you disconnect it, and X session will not start.
Cheers!