Ubuntu – Want to disable built-in screen by default

displaymultiple-monitorsxrandr

Some background: My old, well-loved laptop has kicked the bucket. The normally well-backlit screen is entirely, illegibly darkened. It seems to my inexpert inspection to be a hardware problem well beyond my ken.

My actual question regards my adaptation to this situation: I can still use the computer by attaching another monitor to the laptop and using that to satisfy my graphical needs. The default dual-screen behavior of Ubuntu is to treat the screens as a side-by-side affair, which is irksome since i can only see what's being displayed on one of the screens. I would like to configure Ubuntu (or xorg, or what have you) to treat an attached screen as the single working screen, such that it does not attempt to use the built-in screen in any way.

I've considered (but not actually tried to make the default) the Mirror Displays option available in System Settings (in 14.04), but this seems to result in awkward resolution changes in an attempt to accommodate both screens (even though one of them I'm not concerned with in the slightest). I figure that if I'm lugging this laptop about to plug into many other available monitors, this would probably lead to some hair-splittingly weird visual inconsistency.

My more reasonable solution is to just try to use xrandr to turn off the offending screen. In particular,

xrandr --output LVDS1 --off

appears to do what I was hoping, but this seems like a rather low-hanging, impermanent fix. (LVDS1 is the name of my built-in screen as X knows of it, as revealed by xrandr -q.) I'm hoping to use something a bit deeper, so that I can be certain that I can use this laptop even in situations where I wouldn't have an X server running, say.

Best Answer

xrandr is a difficult way to perform this; I don't recommend it.

Go to System Settings > Screen Display.

You will see both of your screens.

By selecting a screen, you can modify its defaults such as its resolution — and you can turn it off altogether (slide the ON button to OFF).

Be sure to locate the Launcher on "All displays" so that you don't end up missing the launcher.

The settings should be remembered after rebooting.