As you might know (or have found out): AtomicParsley doesn't do batch processing. It does not suppoort it via some switch, nor does it allow to be fed with multiple files via shell's file globbing like "./*".
$ for f in *.m4a; do /opt/AtomicParsley-debian-0.9.0/AtomicParsley "$f" --artist "(insert artist here)" --album "(insert album title here)" --overWrite; done
What we do here: We call atomicparsley, residing in /opt here, to add artist and album name to a whole directory full of m4a files (aac audio in an mpeg-4 container). We used the undocumented --overWrite switch to have atomicparsley replace the input files.