GNU bug report logs - #8490
dd reads random number of records from pipes - named or otherwise - coreutils 8.9

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From: Eric Blake <eblake <at> redhat.com>
To: Bjartur Thorlacius <svartman95 <at> gmail.com>
Cc: 8490 <at> debbugs.gnu.org, Jesse Gordon <jesseg <at> nikola.com>
Subject: bug#8490: dd reads random number of records from pipes - named or	otherwise - coreutils 8.9
Date: Wed, 13 Apr 2011 09:13:59 -0600

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On 04/13/2011 08:39 AM, Bjartur Thorlacius wrote:
> Have you looked into fullblock? If you only specify bs and  count (and
> not ibs or obs) dd may fill the buffer partially. It'll do try to do
> count copies, but each copy may contain less data than expected. This
> sort of makes sense on HDDs or tapes with variable block sizes (where
> a read would return a whole block, but the block would be smaller than
> user specified bs). In this case dd will preserve the original block
> size. I've never encountered such an odditie — Or maybe I have,
> without noticing.
> 
> I think about noone that hasn't been involved in the development, in
> one way or another, gets this wrong (I don't quite get it yet). I
> think this should be changed, unless the user provids a hypothetical
> partblock option.

It can't be changed without changing POSIX.

-- 
Eric Blake   eblake <at> redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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