dd Bug using \.\PhysicalDriveX ?

Eric Blake ebb9@byu.net
Wed Sep 19 18:24:00 GMT 2007

Scalzott, Todd <tscalzott <at> kastle.com> writes:

> I believe that this is part of CORE, which I have at 6.9-5.  I did
> update to all of the latest just a short while ago and reverified the
> problem.

There's no such thing as CORE in the cygwin distribution; you meant coreutils.

> I've discovered what I believe to be a problem with "dd" on several
> different XP SP2 systems with Cygwin installed involving the usage of
> Windows' \\.\PhysicalDrive nomenclature.

That's your problem.  Cygwin is a Linux emulation, and use of Window's \\.\ 
nomenclature is not guaranteed to work.  Using the corresponding posix-y name 
is more likely to succeed, in which case the bug is not in dd but in your usage.

> That is, reading from \\.\PhysicalDrive1 with the below command works
> flawlessly:
>     dd if=^\^\.^\PhysicalDrive1 of=tmp.img bs=16384

That's an unusual quoting style; it certainly doesn't work under bash.  Are you 
by chance trying this under cmd.com?  In which case, why are you bothering with 
quoting? cmd.com passes \ through without the need for quoting.

At any rate, what you probably wanted something more like this (less typing, 
and no need for quoting, whether in cmd.com or bash):

dd if=tmp.img of=/dev/sda bs=16K

See http://cygwin.com/cygwin-ug-net/using-specialnames.html for more details.

Eric Blake
volunteer cygwin coreutils maintainer

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