GNU bug report logs - #62272
Erroneous claim in grep man page

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: David Kra <dakra137 <at> gmail.com>
To: bug-grep <at> gnu.org
Subject: Erroneous claim in grep man page
Date: Sun, 19 Mar 2023 11:27:41 +0200

[Message part 1 (text/plain, inline)]

This is a request and further endorsement of a report from 2008, ending
with https://lists.gnu.org/archive/html/bug-grep/2008-08/msg00002.html

Request: Either add four words to the manpage or delete the entire
sentence.
ASIS: "In GNU grep there is no difference in available functionality
between basic and extended syntaxes."

TOBE: "Although the syntaxes differ, in GNU grep there is no difference in
available functionality between basic and extended syntaxes."

Reasoning: The user should not suffer for not realizing that "no difference
in available functionality" does not imply "no difference in syntax."
Example:
*$* *grep -i "([A-Z])\1\1" *
grep: Invalid back reference
#but no problem with:
*$* *grep -i -E "([A-Z])\1\1"*
or
*$* *grep -i "\([A-Z]\)\1\1" *
---
Thank you,
*David A. Kra*
__________________________________________________________________

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Message #10 received at 62272-done <at> debbugs.gnu.org (full text, mbox):

From: Jim Meyering <jim <at> meyering.net>
To: dakra137 <at> gmail.com
Cc: 62272-done <at> debbugs.gnu.org
Subject: Re: bug#62272: Erroneous claim in grep man page
Date: Sun, 19 Mar 2023 18:54:32 -0700

tags notabug 62272
stop

On Sun, Mar 19, 2023 at 5:47 AM David Kra <dakra137 <at> gmail.com> wrote:
> This is a request and further endorsement of a report from 2008, ending
> with https://lists.gnu.org/archive/html/bug-grep/2008-08/msg00002.html
>
> Request: Either add four words to the manpage or delete the entire
> sentence.
> ASIS: "In GNU grep there is no difference in available functionality
> between basic and extended syntaxes."
>
> TOBE: "Although the syntaxes differ, in GNU grep there is no difference in
> available functionality between basic and extended syntaxes."
>
> Reasoning: The user should not suffer for not realizing that "no difference
> in available functionality" does not imply "no difference in syntax."

Thanks, but that sentence already says there are two different
syntaxes: basic and extended.
Those are different names, which usually implies they denote different things.
So adding those four words at the beginning of the sentence would be
unnecessary and repetitive.

I'm marking this as done, but discussion may continue.

Message #13 received at 62272 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: dakra137 <at> gmail.com
Cc: 62272 <at> debbugs.gnu.org
Subject: Re: bug#62272: Erroneous claim in grep man page
Date: Mon, 20 Mar 2023 00:29:49 -0700

[Message part 1 (text/plain, inline)]

On 2023-03-19 02:27, David Kra wrote:

> TOBE: "Although the syntaxes differ, in GNU grep there is no difference in
> available functionality between basic and extended syntaxes."

I'm not a fan of "syntaxes". Although it is a word in computer science 
it grates in my ear because in linguistics "syntax" is a field of study 
and there is only one syntax just as there is only one rhetoric and 
there is only one logic.

Anyway (to get off my soapbox :-) there's a bigger problem in the next 
sentence, which says, "In other implementations, basic regular 
expressions are less powerful." That's not true for POSIX BREs, as they 
have back-references, which POSIX EREs lack. (This is documented in the 
GNU grep manual's "Problematic Expressions" section.) And I doubt 
whether it's true that PCRE2 is a strict superset of EREs so we should 
scale the wording back a bit there too.

I installed the attached doc patch, which I hope fixes these problems. 
(It also fixes a couple of troff typos I noticed in the neighborhood.)

[0001-doc-clarify-BRE-vs-ERE-bug-62272.patch (text/x-patch, attachment)]

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