UnRAR shell script for (multiple) RAR files

#!/bin/bash
#Thanks locsemege

ext=("001" "[pP][aA][rR][tT]*.[rR][aA][rR]" "[rR][aA][rR]")
ext_to_delete=("[0-9][0-9][0-9]" "[pP][aA][rR][tT]*.[rR][aA][rR]" "[r-zR-Z][aA0-9][rR0-9]")
error="$(mktemp)"
extracted=0

extract_it() {

   local filename=""

   for i in $(seq ${#ext[@]}); do
      filename="${1%.${ext[i-1]}}"
      if [ "$filename" != "$1" ]; then
         break
      else
         filename=""
      fi
   done

   if [ "$filename" = "" ]; then
      return 0
   fi

   echo "Extracting $1..."
   unrar x -y "$1" 1>/dev/null 2>$error

   if [ ! -s $error ]; then

      ((extracted++))

      rm -f "$filename.sfv"
      rm -f "$filename."${ext_to_delete[i-1]}

      if [ -f "$filename.bin" ]; then
         echo "Converting..."
         bchunk "$filename.bin" "$filename.cue" "$filename" 1>/dev/null 2>$error
         if [ ! -f "${filename}02.cdr" ]; then
            rm -f "$filename.bin" "$filename.cue"
            mv "${filename}01.iso" "$filename.iso"
         else
            rm -f "${filename}01.iso"
            rm "$filename"[0-9][0-9]".cdr"
            echo "$filename.bin can't convert to .iso, it conains audio tracks!"
         fi
      fi
   else
      cat "$error" 2>/dev/null
   fi
}

do_it() {
   if [ -z "$1" ]; then
      for f in * ; do
         if [ "$f" != ".." ] ; then
            if cd "$f" 2>/dev/null; then
               do_it
               cd ..
            elif [ -f "$f" ]; then
               extract_it "$f"
            fi
         fi
      done
   else
      extract_it "$1"
   fi
}

do_it "$1"

case $extracted in
   0)
      echo "Nothing to extract"
   ;;
   1)
      echo "1 archive extraxted"
   ;;
   *)
      echo "$extracted archives extraxted"
   ;;
esac

echo Done
cat "$error" 2>/dev/null
rm -f "$error"