Xrandr

Xrandr is a command line tool used for dynamically changing X screens. It is the basic interface to the RandR X extensions.

Useful Incantations

In order to use a machine on projector, you may want to mirror your screen to be the same as what is displayed on the projector. This mirrors your primary screen (assumed to be LVDS1) to the first VGA console (VGA1), then sets your screen to have a 1024x768 resolution (which should be the same as the projector)

xrandr --output LVDS1 --mode 1024x768 --output VGA1 --same-as LVDS1

To revert to the default settings

xrandr --output LVDS1 --auto