Geoffrey,
Lots of things tend to work better when they're plugged in. :-)
There are two main rig control programs for Linux that I'm aware of. One, grig, is in the Ubuntu repositories under "Amateur Radio". The other, flrig, is available through the developer's web site at
http://w1hkj.com. I've used both and IMO flrig is nicer and better maintained, but YMMV. (Plus Dave, the developer of flrig, is approachable and responsive, and there's an active Yahoo group for Dave's software.) Try both and see.
73, Creede WA7KPK