GNU bug report logs - #15937
inconsistent behavior when using the -f option

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

From: Aaron Selk <aaron_selk <at> generalplastics.com>
To: "bug-grep <at> gnu.org" <bug-grep <at> gnu.org>
Subject: inconsistent behavior when using the -f option
Date: Wed, 20 Nov 2013 19:34:51 +0000

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The following command produces matches.
# egrep ^[\[].+[\]] /var/log/apache2/error.log

However, if I save the pattern to a file and use the -f option, it produces no matches.
I have to change the pattern to this:
^[\[].+\]

Notice I had to remove the enclosing square brackets to get the literal closing bracket to match when using the -f option.
This is on a Debian Squeeze system. Below is the package information. I am happy to provide more details if you needed.
# apt-cache show grep

Package: grep
Essential: yes
Priority: required
Section: utils
Installed-Size: 1148
Maintainer: Anibal Monsalve Salazar <anibal <at> debian.org>
Architecture: amd64
Version: 2.6.3-3+squeeze1
Provides: rgrep
Depends: dpkg (>= 1.15.4) | install-info
Pre-Depends: libc6 (>= 2.3)
Suggests: libpcre3 (>= 7.7)
Conflicts: rgrep
Filename: pool/main/g/grep/grep_2.6.3-3+squeeze1_amd64.deb
Size: 313920
MD5sum: 7c8b301e28fc614cd99b04ea87ad0fee
SHA1: 7ebde8d23c4efe40d6744ec9f79133c37b7d2150
SHA256: e0bb207f1446f5b560540df30cee048fe623b5de164c5e035323cffb59de1736
Description: GNU grep, egrep and fgrep
'grep' is a utility to search for text in files; it can be used from the
command line or in scripts.  Even if you don't want to use it, other packages
on your system probably will.
.
The GNU family of grep utilities may be the "fastest grep in the west".
GNU grep is based on a fast lazy-state deterministic matcher (about
twice as fast as stock Unix egrep) hybridized with a Boyer-Moore-Gosper
search for a fixed string that eliminates impossible text from being
considered by the full regexp matcher without necessarily having to
look at every character. The result is typically many times faster
than Unix grep or egrep. (Regular expressions containing backreferencing
will run more slowly, however.)
Homepage: http://www.gnu.org/software/grep/
Tag: implemented-in::c, interface::commandline, role::program, scope::utility, suite::gnu, use::searchin

Package: grep
Essential: yes
Status: install ok installed
Priority: required
Section: utils
Installed-Size: 768
Maintainer: Anibal Monsalve Salazar <anibal <at> debian.org>
Architecture: amd64
Version: 2.6.3-3
Provides: rgrep
Depends: dpkg (>= 1.15.4) | install-info
Pre-Depends: libc6 (>= 2.3)
Suggests: libpcre3 (>= 7.7)
Conflicts: rgrep
Description: GNU grep, egrep and fgrep
'grep' is a utility to search for text in files; it can be used from the
command line or in scripts.  Even if you don't want to use it, other packages
on your system probably will.
.
The GNU family of grep utilities may be the "fastest grep in the west".
GNU grep is based on a fast lazy-state deterministic matcher (about
twice as fast as stock Unix egrep) hybridized with a Boyer-Moore-Gosper
search for a fixed string that eliminates impossible text from being
considered by the full regexp matcher without necessarily having to
look at every character. The result is typically many times faster
than Unix grep or egrep. (Regular expressions containing backreferencing
will run more slowly, however.)
Homepage: http://www.gnu.org/software/grep/


Aaron Selk
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Tacoma, WA 98409
Ph: 253.473.5000
Fax: 253.473.5104
www.generalplastics.com

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Message #8 received at 15937 <at> debbugs.gnu.org (full text, mbox):

From: Jim Meyering <jim <at> meyering.net>
To: Aaron Selk <aaron_selk <at> generalplastics.com>
Cc: 15937 <at> debbugs.gnu.org
Subject: Re: bug#15937: inconsistent behavior when using the -f option
Date: Wed, 20 Nov 2013 16:53:48 -0800

tags 15937 notabug
close 15937
thanks

On Wed, Nov 20, 2013 at 11:34 AM, Aaron Selk
<aaron_selk <at> generalplastics.com> wrote:
> The following command produces matches.
> # egrep ^[\[].+[\]] /var/log/apache2/error.log
>
> However, if I save the pattern to a file and use the -f option, it produces no matches.
> I have to change the pattern to this:
> ^[\[].+\]
>
> Notice I had to remove the enclosing square brackets to get the literal closing bracket to match when using the -f option.

Thanks for the report, but the only problem is that you have not
quoted the regular expression, and that makes it subject to evaluation
by your shell.

I suggest trying hard to single-quote (double-quote only when
necessary) grep regular expressions that are specified on the command
line.
This demonstrates that a properly-quoted regexp works the same on the
command line as when included as the contents of an -f-specified file:

$ echo '[x]' | grep -E '^[[].+[]]'
[x]
$ echo '[x]' | grep -E -f <(echo '^[[].+[]]')
[x]

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