GNU bug report logs - #23185
GNU grep matching discrepancy between -a/--text and not.

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Shlomi Fish <shlomif <at> shlomifish.org>
Subject: bug#23185: closed (Re: bug#23185: GNU grep matching discrepancy
 between -a/--text and not.)
Date: Wed, 06 Apr 2016 06:57:02 +0000

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Your bug report

#23185: GNU grep matching discrepancy between -a/--text and not.

which was filed against the grep package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 23185 <at> debbugs.gnu.org.

-- 
23185: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=23185
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

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From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Shlomi Fish <shlomif <at> shlomifish.org>, 23185-done <at> debbugs.gnu.org
Subject: Re: bug#23185: GNU grep matching discrepancy between -a/--text and
 not.
Date: Tue, 5 Apr 2016 23:56:22 -0700

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Thanks for pointing out the seeming inconsistency. The documentation mentions 
the issue but is perhaps not clear enough, so I installed the attached patch.

The input file contains NUL bytes and so is treated as binary data, and the grep 
documentation (secton "File and Directory Selection", option "--binary-files") 
says "When processing binary data, ‘grep’ may treat non-text bytes as line 
terminators". This behavior was added to GNU grep in release 2.21 dated 2014, 
partly for performance reasons.

There are two instances in riddle.he of a space followed by a NUL byte, so

  grep -P '[ \t]\r?$' riddles.he

finds a match when the $ matches just before the NUL byte.

-a is one way to get the behavior you evidently expected. Another (perhaps 
better) way is -z. The command:

  grep -zP '[ \t]\r?\n' riddles.he

outputs nothing and exits with status 1.

[0001-Give-another-example-of-binary-file-processing.patch (text/x-diff, attachment)]

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From: Shlomi Fish <shlomif <at> shlomifish.org>
To: bug-grep <at> gnu.org
Subject: GNU grep matching discrepancy between -a/--text and not.
Date: Sat, 2 Apr 2016 15:00:12 +0300

Hi all,

as can be seen in this repository:

https://github.com/shlomif/gnu-grep-trailing-space-and-CR-on-riddles.he-false-match

GNU grep says a document it suspects to be binary matches without -a/--text and
doesn't match it or return results with that flag applied. perl sides with the
latter.

I'm on Mageia linux x86-64 v6 and have built GNU grep from the latest git
commit ( c767ed70eca9a82d76f07dcdbcaafa21ec7f86d6 ) to test.

Regards,

	Shlomi Fish

P.S: it seems the build system uses gperf but configure does not verify that it
exists in the path.

-- 
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Shlomi Fish       http://www.shlomifish.org/
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