GNU bug report logs - #18863
grep -b bug

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

From: 王琦 <wq_brilliant <at> 163.com>
To: "bug-grep <at> gnu.org" <bug-grep <at> gnu.org>
Subject: grep -b bug
Date: Mon, 27 Oct 2014 15:49:12 +0800

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Hi, I found that "grep -b" doesn't work on my machine. the expected result for below command is "7:not", but I got 0 $ echo gnu is not unix | grep -b -o "not" 0:not Bash version 3.2.25 Linux version 2.6.18 Thanks. 发自邮箱大师

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Message #12 received at 18863-done <at> debbugs.gnu.org (full text, mbox):

From: Eric Blake <eblake <at> redhat.com>
To: 王琦 <wq_brilliant <at> 163.com>, 18863-done <at> debbugs.gnu.org
Subject: Re: bug#18863: grep -b bug
Date: Tue, 28 Oct 2014 06:37:58 -0600

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tag 18863 notabug
thanks

On 10/27/2014 01:49 AM, 王琦 wrote:
> Hi, I found that "grep -b" doesn't work on my machine. the expected result for below command is "7:not", but I got 0 $ echo gnu is not unix | grep -b -o "not" 0:not Bash version 3.2.25 Linux version 2.6.18 Thanks. 发自邮箱大师

[your report was hard to read because you failed to use line wrapping]

Thanks for the report.  However, I cannot reproduce it on newer grep,
and have to assume the error has either been fixed in the meantime.
Therefore, I'm closing out this bug report, although you should feel
free to make further comments or even reopen this if you can demonstrate
that a problem still exists.

$ grep --version | head -n1
grep (GNU grep) 2.18
$ echo gnu is not unix | grep -b -o not
7:not

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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Message #15 received at 18863 <at> debbugs.gnu.org (full text, mbox):

From: Norihiro Tanaka <noritnk <at> kcn.ne.jp>
To: <wq_brilliant <at> 163.com>
Cc: 18863 <at> debbugs.gnu.org
Subject: Re: bug#18863: grep -b bug
Date: Tue, 28 Oct 2014 21:45:09 +0900

> Hi, I found that "grep -b" doesn't work on my machine. the expected
> result for below command is "7:not", but I got 0 $ echo gnu is not
> unix | grep -b -o "not" 0:not Bash version 3.2.25 Linux version 2.6.18

What is version of your grep?  I trid your test case on CentOS 5.10, and
I got the same results as you.  As the bug was fixed in grep 2.6, it
does not occur in grep 2.20 which is most recently version.

$ uname -a
Linux cent58 2.6.18-371.el5 #1 SMP Tue Oct 1 08:37:57 EDT 2013 i386 i386 i386 GNU/Linux
$ bash --version
GNU bash, version 3.2.25(1)-release (i386-redhat-linux-gnu)
........
$ cat /etc/redhat-release
CentOS release 5.10 (Final)

$ echo gnu is not unix | env LC_ALL=C /bin/grep -b -o "not"
0:not
$ env LC_ALL=C /bin/grep --version
grep (GNU grep) 2.5.1
........

$ echo gnu is not unix | env LC_ALL=C grep -b -o "not"
7:not
$ env LC_ALL=C grep --version
grep (GNU grep) 2.20
........
Written by Mike Haertel and others, see <http://git.sv.gnu.org/cgit/grep.git/tree/AUTHORS>.

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