need to convert all the mp3’s in a directory to wave to burn in xcdroast ?

here is an easy way:
for x in *mp3 ; do lame --decode `echo $x | cut -d. -f1`.mp3 `echo $x | cut -d. -f1`.wav ; done

obviously this assumes you have lame installed

EDIT 06.17.09 – converting wma to mp3’s (found this using “the google”, not mine):
for i in *.wma ; do mplayer -vo null -vc dummy -af resample=44100 -ao pcm:waveheader "$i" && lame -m j -h --vbr-new -b 160 audiodump.wav -o "`basename "$i" .wma`.mp3"; done; rm -f audiodump.wav
this assumes you have mplayer & lame