#!/bin/bash                                                                                                                                                                           
#                                                                                                                                                                                     
# renaming *.mp3 in the current directory                                                                                                                                             
# according to the following rules:                                                                                                                                                   
#                                                                                                                                                                                     
#                                                                                                                                                                                     
# uppercase -> lowercase ('Artist - Title.mp3' -> 'artist - title.mp3')
#
# 'ä', 'ö', 'ü' -> 'ae', 'oe', 'ue' ('artist - title-ä.mp3' -> artist - title-ae.mp3') 
#
# ' ' -> '_' ('artist - title.mp3' -> 'artist_-_title.mp3')
#
# '&', '+' -> 'and' ('artist1_&_artist2___title(2005).mp3' -> ''artist1_and_artist2___title(2005).mp3')
#
# '(' -> '__' and ')' -> '' ('artist___title(2005).mp3' -> 'artist___title__2005.mp3')
#
# '_-_' -> '___' ('artist_-_title.mp3' -> 'artist___title.mp3')
#                                                                                                                                                                                     
#                                                                                                                                                                                     
# to replace more characters just add a '| sed "s/$what_to_rename/$newchar/g"' in front of the ')'
 
for file in *.mp3; do {                                                                                                                                                               
                                                                                                                                                                                      
newfile=$(echo "$file" | tr [:upper:] [:lower:] | sed "s/[ö|Ö]/oe/g" | sed "s/[ä|Ä]/ae/g" | sed "s/[Ü|ü]/ue/g" | sed "s/ /_/g" | sed "s/[&|+]/and/g" | sed "s/(/__/g" | sed "s/)//g" | sed "s/_-_/___/g")

if [ "$file" == "$newfile" ]; then sleep 0; else mv -v "$file" "$newfile"; fi

}

done