I like to leave my computer on 24/7.  Having an ‘uptime’ of months is a matter of personal satisfaction for me, and is really one of the reasons I like Linux - if something goes wrong you can usually fix it without restarting.  Today I encountered a problem that a user with a normal usage pattern probably never would have noticed, as it would have been fixed if I had restarted.

My sound stopped working today.  I would open Amarok and try to start playback and it would look like it was playing (the eq was bouncing), but no sound was coming out.  I went to a command prompt and tried to use the ‘madplay’ command line utility to play an mp3.  It gave me the error: “/dev/dsp: Device or resource busy”.  I did a quick search on that error message and came up with some helpful articles that led me to believe that maybe a certain process was monopolizing my sound device and not letting other processes access it.  On advice of this forum post, I was able to use the ‘lsof’ tool to find which process was locking up my audio device and then end that process.  Here is the command I used:

lsof /dev/snd/*

I was able to see that ‘firefox’ was using my sound device, so I just closed firefox, and sure enough that fixed it.