Dear All I use the script ------------------------------------------- #!/bin/sh blocos=`echo $(( $(ls -l "$1" | awk '{ print $5 }') / 2048 ))` disksum=`dd if=/dev/dvd bs=2048 count=$blocos | md5sum - "$1"` echo "$disksum" ------------------------------------------- to check whether a data dvd has been well recorded (comparing its md5sums with the md5sums of the corresponding iso file). However, with a certain iso file, I always get two not matching md5sums. The media that I am using is a Philips DVD+RW, and the recording speed is low (4x). Any ideas? Thanks in advance, Paul