Recording an audio source in linux

I'm using Fedora Core on an i386 platform. I have a sound card that seems to be working fine and allows me to record to a file from either the mic or a line in. What I'd like to do is attach a radio scanner to the line in and record the scanner output to a file (preferably mp3, but I'm not picky at this point) in 30 minute long files 24 hours a day. I'd like this to be automated so I don't have to manual start and stop recording. I have ices and icecast running, but I'm not locked into using them.

I use to be more proficient with linux, but I've never been a coder. I'm sure a script would serve my purpose, but I wouldn't know what to put in it. I'd love to have an application that could take care of it all.

Any thoughts?

Michael