Cut or trim mp3 files with Linux, mpgsplit and mp3cut
1. mpgtx
To install this program under Debian
sudo aptitude install mpgtx
Now if you want to trim a mp3 file into 10 pieces just enter this command
mpgtx -10 input.mp3 -o output
You will get output01.mp3, output02.mp3 .... output10.mp3 files, and now you can easily transport them, use them as ringtones, or anything you need.
Now if you want to cut an specific part of the mp3 file you may use ranges:
mptsplit input.mp3 [00:00:20-00:00:58] -o output.mp3
Now you will have from the 20th second to the 58th second of the song, in output.mp3 file, which is great for creating ringtones for your cellular.
RTFM for more options, as you can also join files and some other useful things.