./ufo +set vid_mode -1 +set vid_height 1024 +set vid_width 1920
Correcting the above for use with a wide screen netbook.
Also this is not needed and may not work with some linux builds andolder builds will still need it.
./
This works with kubuntu 11.04
ufo +set vid_mode -1 +set vid_height 600 +set vid_width 1024
Edit: after installing this on 7 other computers, (lan party) the best way to get it to go into full screen is to do the above and change both the hight and width to 500. Then start the game, go into the video seeings and set it to one of the 3 built in settings then you can put it in full screen. After that quit the game so it saves the setting, just encase the game locks up or crashes.