xrandr

Xrandr is used to set the screen size, orientation and/or reflection.

The -s option is a small integer index used to specify which size the screen should be set to. To find out what sizes are available, use the -q option, which reports the sizes available, the current rotation, and the possible rotations and reflections. The default size is the first size specified in the list.

The -o option is used to specify the orientation of the screen, and can be one of "normal inverted left right 0 1 2 3". The -x option instructs the server to reflect the screen on the X axis. The -y option instructs the server to reflect the screen on the Y axis. Reflection is applied after rotation.

The -help option prints out a usage summary.

The --verbose option tells you what xrandr is doing, selects for events, and tells you when events are received to enable debugging.