Re: Checking burned image is ok
On 07/27/2010 01:50 AM, Mathieu Malaterre wrote:
> Hi there,
>
> I am looking for a way to check I did burn my debian installer iso
> properly. I am trying:
>
> $ cmp /dev/cdrom debian-505-powerpc-netinst.iso
>
> This works on CD-RW, but it fails on CD-R with the following:
>
> cmp: /dev/cdrom: Input/output error
>
> Has anyone seen this before ? How else could I check the CD-R is
> actually properly burned ?
>
> Thanks !
Others have posted regarding using check sums.
The "advantage" to using 'cmp' is you get a byte by byte, exact match check.
If that's what you want or need, use Cesar Garcia's suggestion to get
the parameters of your CD image and use dd to read the disk, only
instead of piping the output to md5sum, do this:
dd .... | cmp - debian.iso
which compares the stdin from dd with the file. This will avoid the
error you noted above.
The "problem" with using cmp directly on the device has to do with how
the device driver handles what would be considered EOF. All that
happened in your cmp run was an attempt to read beyond the end of the
device. Unless 'cmp' produced a "files differ: byte xxxx, line yyy"
type of message, the 'cmp' actually succeeded in properly comparing the
two images.
--
Bob McGowan
Reply to: