[Emacs-bug-tracker] bug#8171: closed ([dd] bs=blocksize doesn't work as expected)

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Your message dated Fri, 04 Mar 2011 14:02:35 +0000
with message-id <address@hidden>
and subject line Re: bug#8171: [dd] bs=blocksize doesn't work as expected
has caused the GNU bug report #8171,
regarding [dd] bs=blocksize doesn't work as expected
to be marked as done.

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8171: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=8171
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> --- Begin Message ---
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> Subject: 
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> [dd] bs=blocksize doesn't work as expected
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> Date: 
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> Fri, 4 Mar 2011 08:02:56 +0300
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> [dd] bs=blocksize doesn't work as expected, for example:
> tar -c /somedir | dd bs=256K of=/dev/nst0
> In this example backup record will be recorded to a tape with block size = 10K instead of 256K because 10K is default for tar.
> There is workaround:
> tar -c /somedir | dd ibs=256K obs=256K of=/dev/nst0
> If we set block size for input and output separatly - it works as expected.
>
> lucid (utils):
> 	The GNU core utilities
>     
>       
> 7.4-2ubuntu2: amd64 i386
>
> --- End Message ---
> --- Begin Message ---
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> Subject: 
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> Re: bug#8171: [dd] bs=blocksize doesn't work as expected
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> Date: 
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> Fri, 04 Mar 2011 14:02:35 +0000
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> User-agent: 
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> Mozilla/5.0 (X11; U; Linux i686; en-US;	rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3
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> On 04/03/11 05:02, Станислав wrote:
> > [dd] bs=blocksize doesn't work as expected, for example:
> > tar -c /somedir | dd bs=256K of=/dev/nst0
> > In this example backup record will be recorded to a tape with block size =
> > 10K instead of 256K because 10K is default for tar.
> > There is workaround:
> > tar -c /somedir | dd ibs=256K obs=256K of=/dev/nst0
> > If we set block size for input and output separatly - it works as expected.
>
> This operation is expected and dictated by POSIX.
> It is surprising though, and I tried to clarify it in the docs:
> http://git.sv.gnu.org/gitweb/?p=coreutils.git;a=commitdiff;h=d5ab0599
>
> Note also that we're currently considering warning
> that iflag=fullblock should be used, but only
> currently in the case were a count is specified,
> as then you get the wrong amount of data as well
> as the wrong sized writes.
> http://debbugs.gnu.org/cgi/bugreport.cgi?bug=7362
>
> cheers,
> Pádraig.
>
>
> --- End Message ---