GNU bug report logs - #19794
Feature Request - CMP

Message received at submit <at> debbugs.gnu.org:

Received: (at submit) by debbugs.gnu.org; 6 Feb 2015 17:12:33 +0000
From debbugs-submit-bounces <at> debbugs.gnu.org Fri Feb 06 12:12:33 2015
Received: from localhost ([127.0.0.1]:35828 helo=debbugs.gnu.org)
	by debbugs.gnu.org with esmtp (Exim 4.80)
	(envelope-from <debbugs-submit-bounces <at> debbugs.gnu.org>)
	id 1YJmSH-0004k8-4u
	for submit <at> debbugs.gnu.org; Fri, 06 Feb 2015 12:12:33 -0500
Received: from eggs.gnu.org ([208.118.235.92]:52936)
 by debbugs.gnu.org with esmtp (Exim 4.80)
 (envelope-from <P@HIDDEN>) id 1YJmSF-0004jt-0G
 for submit <at> debbugs.gnu.org; Fri, 06 Feb 2015 12:12:31 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
 (envelope-from <P@HIDDEN>) id 1YJmS2-0005Ea-Ei
 for submit <at> debbugs.gnu.org; Fri, 06 Feb 2015 12:12:25 -0500
X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on eggs.gnu.org
X-Spam-Level: 
X-Spam-Status: No, score=0.8 required=5.0 tests=BAYES_50 autolearn=disabled
 version=3.3.2
Received: from lists.gnu.org ([2001:4830:134:3::11]:34922)
 by eggs.gnu.org with esmtp (Exim 4.71)
 (envelope-from <P@HIDDEN>) id 1YJmS2-0005EU-CW
 for submit <at> debbugs.gnu.org; Fri, 06 Feb 2015 12:12:18 -0500
Received: from eggs.gnu.org ([2001:4830:134:3::10]:54584)
 by lists.gnu.org with esmtp (Exim 4.71)
 (envelope-from <P@HIDDEN>) id 1YJmS1-0000IJ-EW
 for bug-diffutils@HIDDEN; Fri, 06 Feb 2015 12:12:18 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
 (envelope-from <P@HIDDEN>) id 1YJmRx-0005Bw-BA
 for bug-diffutils@HIDDEN; Fri, 06 Feb 2015 12:12:16 -0500
Received: from mail5.vodafone.ie ([213.233.128.176]:53236)
 by eggs.gnu.org with esmtp (Exim 4.71)
 (envelope-from <P@HIDDEN>)
 id 1YJmRw-00055M-W1; Fri, 06 Feb 2015 12:12:13 -0500
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: AkkFAHX11FRtTrRZ/2dsb2JhbABagwWELcMDgk8CgRlDAQEBAQF9hA0BBSMPAUYQCw0BCgICBRYLAgIJAwIBAgFFBgEMAQcBAYgtAb9ihWmQLAEBAQcBAQEBAR2BIY5XB4JogUEBBJ8bg3GIJiKBfwMcgVA+gnMBAQE
Received: from unknown (HELO localhost.localdomain) ([109.78.180.89])
 by mail3.vodafone.ie with ESMTP; 06 Feb 2015 17:12:10 +0000
Message-ID: <54D4F5E9.3040909@HIDDEN>
Date: Fri, 06 Feb 2015 17:12:09 +0000
From: =?UTF-8?B?UMOhZHJhaWcgQnJhZHk=?= <P@HIDDEN>
User-Agent: Mozilla/5.0 (X11; Linux x86_64;
 rv:31.0) Gecko/20100101 Thunderbird/31.4.0
MIME-Version: 1.0
To: Eric Blake <eblake@HIDDEN>, Tyler Beaver <tyler9725@HIDDEN>
Subject: Re: Feature Request - CMP
References: <CA+Xn=xoTTJ6bX+RTJfc9dLW1CZ2=sHreDwKZmXxOaT2e3viQKA@HIDDEN>
 <54D4EA6C.40204@HIDDEN> <54D4EF96.2010703@HIDDEN>
 <54D4F4D5.5020004@HIDDEN>
In-Reply-To: <54D4F4D5.5020004@HIDDEN>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
X-detected-operating-system: by eggs.gnu.org: Genre and OS details not
 recognized.
X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address
 (bad octet value).
X-Received-From: 2001:4830:134:3::11
X-Spam-Score: -5.0 (-----)
X-Debbugs-Envelope-To: submit
Cc: bug-diffutils@HIDDEN, coreutils@HIDDEN
X-BeenThere: debbugs-submit <at> debbugs.gnu.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: <debbugs-submit.debbugs.gnu.org>
List-Unsubscribe: <https://debbugs.gnu.org/cgi-bin/mailman/options/debbugs-submit>, 
 <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=unsubscribe>
List-Archive: <https://debbugs.gnu.org/cgi-bin/mailman/private/debbugs-submit/>
List-Post: <mailto:debbugs-submit <at> debbugs.gnu.org>
List-Help: <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=help>
List-Subscribe: <https://debbugs.gnu.org/cgi-bin/mailman/listinfo/debbugs-submit>, 
 <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=subscribe>
Errors-To: debbugs-submit-bounces <at> debbugs.gnu.org
Sender: "Debbugs-submit" <debbugs-submit-bounces <at> debbugs.gnu.org>
X-Spam-Score: -5.0 (-----)

On 06/02/15 17:07, Eric Blake wrote:
> On 02/06/2015 09:45 AM, Eric Blake wrote:
>> On 02/06/2015 09:23 AM, Pádraig Brady wrote:
>>> On 06/02/15 15:57, Tyler Beaver wrote:
>>>> I know this tool is probably note used as much anymore, but perhaps it would be worth adding a flag for overriding the verbose output number system for the values, or at any rate specifying that this output is in octal, and not decimal or hexadecimal.
>>>
>>> Currently: offsets are decimal, differing bytes are octal:
>>>
>>>   $ cmp -l <(echo 12345678abc) <(echo 12345678bbb)
>>>                     9 141 142
>>>                    11 143 142
> 
> Another observation: Note that when mixed with --ignore-initial, we
> behave as if offsets start from the point where we skipped to, rather
> than the beginning of the file.  Since -i is not required by POSIX, does
> this always make the most sense?
> 
> $ cmp -l     <(printf bbc) <(printf abd)
>                   1 142 141
>                   3 143 144
> $ cmp -l -i1 <(printf bbc) <(printf abd)
>                   2 143 144
> 
> and what happens when we use the two-offset form?
> 
> $ cmp -l -i2:1 <(printf abcd) <(printf bce)
>                   2 144 145
> $ cmp -l -i1:2 <(printf bce) <(printf abcd)
>                   2 145 144
> 
> 
>> That said, it might be worth patching 'cmp --help' to make it obvious
>> that differing bytes are in octal values.
> 
> That is, instead of
> 
>   -l, --verbose              output byte numbers and differing byte values
> 
> maybe we could use:
> 
>   -l, --verbose              for each difference, output the decimal
>                              offset and the differing octal values
> 
> Expanding that to two lines can be offset by compressing elsewhere:
> 
>   -i, --ignore-initial=SKIP         skip first SKIP bytes of both inputs
>   -i, --ignore-initial=SKIP1:SKIP2  skip first SKIP1 bytes of FILE1 and
>                                       first SKIP2 bytes of FILE2
> 
> feels long; how about:
> 
>   -i, --ignore-initial=SKIP[:SKIP2]  bypass SKIP bytes of FILE1, and
>                                      SKIP2 (default SKIP) bytes of FILE2

Good suggestions,
which I've CC'd the the appropriate list ;)

cheers,
Pádraig.