These are baically notes for me, but it might help someone else.
Needless to say, you can’t connect an iphone to Linux yet without jail-breaking your phone, or buying another computer with a ‘supported’ OS like mac or windows.
Update: using Fedora 15 or later, the iPhone does connect under Linux and you can browse it! Wooh!
Nevertheless, the tools on Linux are fantastic to edit sound and do gobs of other stuff…
1) ring tones have to be less than 30 seconds in length… so use Audacity to edit your favourite audio file to a nice <30 second clip.
2) Save that selection as a .wav (16 bit stereo PCM) file.
3) in a command prompt type something like this:
faac -b 128 -c 44100 -w --title TITLE mysound.wav
and it will produce something like mysound.m4a
4) rename it to be mysound.m4r (because ringtones are aac with the .m4r extension — whatever)
5) transfer that on your iTunes 'supported' OS (bah – ridiculous) that you can connect your iPhone to and transfer the file into the ringtones folder.
6) sync the iphone.