Creates a m3u file for each album (a directory). Each mp3 is prefixed with it's position in the playlist: "1 - filename.mp3". The m3u is named like the directory of the album and contains the name of the .mp3 without prefix. The prefix is then removed from every mp3.

create_playlist.sh

#!/bin/bash
# file name: "1 - songname.mp3"

delimiter="-"
delimiter_space=1 #characters after the delimiter until the songname starts

find * -type f -name '*.mp3' | while read path; do
        dir=$(dirname "${path}")
        filename=${path##*/}
        cut=$(awk -v a="${filename}" -v b="${delimiter}" 'BEGIN{print index(a,b)}')
        tmp="${filename%.*}"
        songname=${tmp:cut+delimiter_space}
        album=${dir##*/}
        echo $songname.mp3 >> "$dir/$album.m3u"
        mv "$dir/$filename" "$dir/$songname.mp3"
done

echo "finished :)"