id3 multiple edit

id3medit.sh

#!/bin/bash 

counter=0

if [ -n "$1" ]; then
 if [[ $1 = "help" ]]; then
   echo syntax: id3medit artist album year\(*\) genre\(*\)
   echo *=optional
   exit 0
 else
  artist=$1
 fi
else
  echo syntax: id3medit artist album year\(*\) genre\(*\)
  echo *=optional
  exit 0
fi

if [ -n "$2" ]; then 
 album=$2
fi

if [ -n "$3" ]; then
 year=$3
else
 year=0000
fi

if [ -n "$4" ]; then
 genre=$4
else
 genre=255
fi

for file in *.{[Mm][Pp]3,[Oo][Gg][Gg]}
#for file in *.[Mm][Pp]3
do
 echo \-\-\> Processing file: $file
 id3v2 -D "$file" #we delete old tags
 temp=`echo ${file#**-}`
 #temp=`echo ${temp:2}`
 title=`echo ${temp%.*3}`
 id3v2 -t "$title" -T $counter -a "$artist" -A "$album" -y $year -g $genre "$file"
 let 'counter +=1' 
done 

let 'counter -=1'
echo Work done!
echo Converted $counter files,
echo "See you... ;-D"