GNU bug report logs - #14846
doc: dd: improve ibs=BYTES description

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Message #8 received at 14846 <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: jidanni <at> jidanni.org
Cc: 14846 <at> debbugs.gnu.org
Subject: Re: bug#14846: dd how to skip one byte from reading the man page
Date: Fri, 12 Jul 2013 17:49:58 +0100

On 07/12/2013 12:50 AM, jidanni <at> jidanni.org wrote:
> If the user tries to figure out how to skip one byte
> just from reading the dd man page, and not info,
> 
> in order to finally figure out how to do
> 
> $ echo abc|dd ibs=1 skip=1
> bc
> 
> it seems
>        ibs=BYTES
>               read up to BYTES bytes at a time (default: 512)
> should be instead
>        ibs=BYTES
>               reset the input block size (default: 512)
> or something...

Hmm I suppose a more direct description is more accurate.


BTW, note the skip_bytes flag which can be used to more
efficiently skip odd sizes:

$ echo abc | dd iflag=skip_bytes skip=1 status=none
bc

$ echo abc | strace -e read dd iflag=skip_bytes skip=1 status=none
read(0, "a", 1)                         = 1
read(0, "bc\n", 512)                    = 3
read(0, "", 512)                        = 0
bc

cheers,
Pádraig.

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