Date: Thu, 4 Apr 2002 23:50:02 -0800 (PST) From: "Crist J. Clark" <cjc@FreeBSD.ORG> To: freebsd-bugs@FreeBSD.org Subject: Re: i386/36774: The hexdump & od commands doesn't present the input data in the same order among their various formats on the IBM PC Message-ID: <200204050750.g357o2k99607@freefall.freebsd.org>
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The following reply was made to PR i386/36774; it has been noted by GNATS.
From: "Crist J. Clark" <cjc@FreeBSD.ORG>
To: Gerald Stoller <Gerald_Stoller@hotmail.com>
Cc: freebsd-gnats-submit@FreeBSD.ORG
Subject: Re: i386/36774: The hexdump & od commands doesn't present the input data in the same order among their various formats on the IBM PC
Date: Thu, 4 Apr 2002 23:40:18 -0800
On Thu, Apr 04, 2002 at 08:40:45PM -0800, Gerald Stoller wrote:
[snip]
> The hexdump & od commands doesn't present the input data in
> the same order among their various formats on the IBM PC (due to the
> order-difference between bytes in byte-pairs and shorts [little-endian]).
hexdump(8) doesn't know where the data came from. It just sees a
stream of bytes.
> For hexdump , look at the pipeline
> echo -123- | hexdump -cxo
> whose output is
> 0000000 - 1 2 3 - \n
> 0000000 312d 3332 0a2d
> 0000000 030455 031462 005055
> 0000006
> and you can see the reversal of the pairs of bytes between the first
> three lines, and also that the columns don't line up.
But that is the correct and expected output.
> >How-To-Repeat:
> Just execute the pipeline
> echo -123- | hexdump -cxo
> >Fix:
> Don't use shorts (or the like) to pick up data in hexdump , use bytes only. 'Twould be better if the first three lines of the output were
> 0000000 - 1 2 3 - \n
> 0000000 2d 31 32 33 2d 0a
# echo -123- | hexdump -e '"%07.7_ao" 16/1 " %02x " "\n"'
> 0000000 055 061 062 063 055 012
# echo -123- | hexdump -b
As to the other point, if you don't do the endian swap it breaks
reading binary data.
--
Crist J. Clark | cjclark@alum.mit.edu
| cjclark@jhu.edu
http://people.freebsd.org/~cjc/ | cjc@freebsd.org
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