md5_cp/calc_md5.sh

#!/bin/bash

folder="/mnt/export/transport"
md5="md5.txt"

## prepare
cat "${md5}" > "${md5}.bak"
md5_tmp=`mktemp`
md5_add="${md5}.add"

#sort & del dublicates
sed -i '/^$/d' "$md5"
cat "$md5" | sort -k 2 | uniq > "$md5_tmp"
cat "$md5_tmp" > "$md5"

cat $md5_tmp | while read line; do
  #get md5
  md5=$(echo $line | cut -c -32)

  #get path of file
  file=$( echo $line | cut -c  34-)

  #wenn datei existiert
  if [ -f "$file" ]; then
    # do nothing
    echo  > /dev/null
  else
    echo "rm $line"
    sed -i "/$md5/d" "$md5"
  fi

done

#search for new files
find "$folder" -type f | grep -v "/.Trash-" | sort | while read line; do
  #save fiel path
  result=$(grep "$line" "$md5"); [ -z "$result" ] && {
    #wenn kein eintrag in liste...
    echo "new $line"
    md5sum "$line" >> "$md5_add"
  }
done
[ -f "$md5_add" ] && {
  cat "$md5_add" >> "$md5"
  rm "$md5_add"
}

#sort & del dublicates
cat "$md5" | sort -k 2 | uniq > $md5_tmp
rm "$md5" && mv $md5_tmp "$md5"

## diff
diff "${md5}" "${md5}.bak"