Re: Checking the md5sum of a burned CD
On 2009-03-19_05:29:17, M. Lewis wrote:
>
> thveillon.debian wrote:
>> M. Lewis a ??crit :
>>> I've burned a CD from a .iso image. Now I want to verify the burning
>>> process worked correctly (there were no errors reported). Note, I
>>> verified the md5sums of the .iso's before I burned them. So now I'd like
>>> to check the burned CD against that md5sum.
>>>
>>> Thanks,
>>> Mike
>> Hi,
>>
>> "md5sum /dev/cdrom" or "md5sum /dev/scd0" works here (Squeeze and
>> Lenny), whatever applies to your system.
>> If you have I/O error check that it's not mounted, and not accessed by
>> some other process (like "kio*" in KDE).
>>
>> Tom
>
> Great. Thanks Tom. I was totally unaware it could be done as simply as that.
>
Several months ago, when Lenny was still 'testing', I had difficulty
with this: On my hardware, the read from /dev/cdrom had extra bytes at
the end and was a longer byte stream than the .iso image from which
the CD was burned. So, of course, compare of md5 sums between CD and
.iso failed. There is a work-around in that one can use dd to copy
from /dev/cdrom just enough blocks to match the length of the .iso
file, and then compute the md5sum of that (truncated) length matching
file. OTOH the problem may not have been hardware, and it may have
been fixed. So if at first you get results that indicate that you have
a badly burned CD, it may be the test that is bad, not the burn.
I have not verified this situation recently, so this is just a warning.
I think there are many people like me who know about this old problem,
so it would be nice for you to report back to the list as to whether or
not it is still there.
--
Paul E Condon
pecondon@mesanetworks.net
Reply to: