GNU bug report logs - #17799
grep 2.5.4 ignoring parts of expression

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Message #13 received at 17799 <at> debbugs.gnu.org (full text, mbox):

From: Norihiro Tanaka <noritnk <at> kcn.ne.jp>
To: Jim Michaels <jmichae3 <at> yahoo.com>
Cc: 17799 <at> debbugs.gnu.org
Subject: Re: bug#17799: grep 2.5.4 ignoring parts of expression
Date: Thu, 19 Jun 2014 00:36:41 +0900

If you don't specify any options, grep regards a pattern as BRE.

http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap09.html#tag_09_03

(', `)' and `?' are treated as normal character in BRE.  If you expect
that they are treated as special character, you must escape them with
backslash.

BTW, I see you want to use ERE.

http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap09.html#tag_09_04

If so, you must specify -E option.  I test below on Fedora 20.

$ cd /usr/include/c++/4.8.2
$ grep -E "#include <(bits/)?random(\.h)?>" * 2>/dev/null
$ grep "#include <(bits/)?random(\.h)?>" * 2>/dev/null
random:#include <bits/random.h>

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