Re: unexpected error w/ dd

[Pádraig Brady]

On 22/11/16 16:45, Billy Crook wrote:
> Pardon my html email, but the inline attached images are relevant.
> 
> I am trying to use dd to zero the (first and) last 512MB of a range of
> partitions on a range of disks.  The blocksizes vary, and I put together a
> one-liner which I thought should do the trick, but it doesn't.
> 
> i specify a bs to match the partition's block size as reported by blockdev
> --getbsz.  I specify a seek= that is less than the number of blocks that
> blockdev --getsz reports.  I should think this would begin writing before
> the end of the partition and continue until the end.  But instead, I
> receive "cannot seek: invalid argument" (0b copied)
> 
> What am I doing wrong?

It's best to just copy & paste text, rather than sending large screenshots.

It's probably best to use `blockdev --getsize64` to get the size in bytes
and divide that by whatever you're specifying to the `dd bs=` parameter.
That will avoid any mismatch between block sizes.
Also I notice negative values passed in some of the commands,
which may be related to this mismatch.