We love simple solutions to problems, and this falls into that category.
A Reddit user has posted a pair of scripts to switch between two displays (a monitor and a TV) in Ubuntu 12.04, but these should be usable in many other versions of Linux as well. He writes:
I currently have a 40″ TV on HDMI (we’ll call this HDMI) and a 22″ monitor (DVI). I don’t want to dual screen these, I simply want one on at a time.
After a bit of difficulty at the start, this is what he came up with.
To switch the monitor off and the TV on:
xrandr --output DVI --off
xrandr --output HDMI --auto
To switch the TV off and the monitor on:
xrandr --output HDMI --off
xrandr --output DVI --auto
Be sure to make the scripts executable before running them.