Merge multiple m4a files Is there an easy way to do this? 

I have several folders with music files that I want to join. So it would be good if there is a batch solution to this problem.
brew install ffmpeg sox

#!/bin/bash

for f in *.m4a; do ffmpeg -i "$f" "${f%m4a}wav"; done
sox *.wav combined.wav
ffmpeg -i combined.wav -acodec libfaac -ac 2 -ab 192k combined.m4a
rm *.wav