Chris Knadle wrote:
> What you can do, and should do to prove this for yourself, is to run
> 'md5sum' and/or 'sha1sum' on the downloaded ISO file, and then on the
> CD/DVDs you burnt directly. i.e. first 'md5sum unbutu-8.10-desktop-i386.iso',
> and then a checkum on the CD device with the CD in the drive, such as
> 'md5sum /dev/hda'. The checksums should come out the same, and most
> likely will, since the Ubuntu media check passed. You'll see that in
> terms of the data written, Nero did the same thing that the program you
> used in Ubuntu did.
Actually, you can't do reliable md5 checksums for comparison by simply
addressing the drive directly. The writer may write extra data to the
disk when closing the session, etc. What you need to do is to get the
checksum of the same number of blocks as the ISO image
=======================================
where the downloaded file is "your_image.iso", the CD/DVD drive is
"/dev/hdc", and the value of "count" in #2 is the result of #1:
1: echo $(( $(ls -l your_image.iso | awk '{ print $5 }') / 2048 ))
2: dd if=/dev/hdc bs=2048 count=zzzzzzzzz | md5sum
then you compare the result of the checksum in #2 to what is in the
checksum file for your downloaded ISO. You'd do a 3-way compare;
download the ISO & it's md5sum file, "md5sum -c <checkfile_name.md5>,
burn the CD, then do the above check of the CD.
This comes from
http://www.g-loaded.eu/2006/10/07/verify-a-burned-cddvd-image-on-linux/
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