gradient fade out last 5 secs from command line

[PGScooter]

Hi,

Is there a command line way that I can gradually fade out an audio file, say, starting from 5 seconds before the file ends?

Thanks.

edit: I have found quelcom and sox. I haven't got either one to work with mp3s, but I think I should be able to figure out how to get sox to work with mp3s.