A silly little way to "watch" a semi-batch job

I'm running a compilation process that may take up to a few hours and that occasionally stops waiting for user input (yeah, I know, I'm working on it). I came up with a silly little way to let it run on background and not have to keep an eye on it... by keeping an ear on it. A little snippet of shell:

while true
do clear
   mv /tmp/last /tmp/old
   ls -l > /tmp/last
   if diff /tmp/old /tmp/last &> /dev/null
   then play /System/Links/Shared/sounds/KDE_Beep_ShortBeep.wav
   fi
   sleep 5
done

I ran this in a directory where the output of the compilation process is being logged, so the constant flow ensures ls -l is always changing... unless the compilation is stuck at a prompt. I used a little KDE beep to avoid disturbing my officemate (play is part of sox).