create m3u playlists
tl;dr: m3u playlist files are just a text file with the list of file names
files in the same directory
ls -1 *.mp3 > playlist.m3u
current directory and subdirectories
find . -type f -iname "*.mp3" | sort > playlist.m3u
absolute paths
find "$(pwd)" -type f -iname "*.mp3" | sort > playlist.m3u