GNU bug report logs - #30105
Additional "grep" parameter to change the exit code from 1 to 0, even if grep doesn't find pattern

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

From: Vasyl Vavrychuk <vvavrychuk <at> gmail.com>
To: bug-grep <at> gnu.org
Subject: Re: Additional "grep" parameter to change the exit code from 1 to 0, 
 even if grep doesn't find pattern
Date: Sun, 14 Jan 2018 07:21:11 +0200

> > I want to suggest my idea about a additional "grep" parameter which
> > would change the exit code 1 to 0, even when "grep" doesn't find a
> > pattern. I.e. something similar to "-0".
>
> Thanks, but you can avoid triggering your trap
> by appending "|| :" to your grep command.
>
> E.g.,
>
>     grep not-found /dev/null || :
>
> Then, even when grep fails, the shell sees only the successful
> exit code from the ":" (always succeeding) built-in command.

It replaces exit status 2 with success too.
I would like to have an option to return success if nothing is found but
still return fail if error happens.

Message #8 received at 30105 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Vasyl Vavrychuk <vvavrychuk <at> gmail.com>, 30105 <at> debbugs.gnu.org
Subject: Re: bug#30105: Additional "grep" parameter to change the exit code
 from 1 to 0, even if grep doesn't find pattern
Date: Sat, 13 Jan 2018 22:57:27 -0800

Vasyl Vavrychuk wrote:
> I would like to have an option to return success if nothing is found but
> still return fail if error happens.

You can use a shell command like this:

grep PATTERN FILE
test $? -lt 2

I don't see the need for a special grep option to handle this problem.

Message #13 received at 30105-done <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Vasyl Vavrychuk <vvavrychuk <at> gmail.com>
Cc: 30105-done <at> debbugs.gnu.org
Subject: Re: bug#30105: Additional "grep" parameter to change the exit code
 from 1 to 0, even if grep doesn't find pattern
Date: Sun, 14 Jan 2018 09:16:41 -0800

Vasyl Vavrychuk wrote:
> Actually I use grep in pipe with
> 
>    set -eo pipefail
> 
> but still there I can do
> 
>    ... | grep exrp || test $? -lt 2 | ...
> 
> Thanks for suggestion.

You're welcome. You'll need to parenthesize of course. Closing the bug.

Message #16 received at 30105 <at> debbugs.gnu.org (full text, mbox):

From: Vasyl Vavrychuk <vvavrychuk <at> gmail.com>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: 30105 <at> debbugs.gnu.org
Subject: Re: bug#30105: Additional "grep" parameter to change the exit code
 from 1 to 0, even if grep doesn't find pattern
Date: Sun, 14 Jan 2018 18:32:42 +0200

Actually I use grep in pipe with

  set -eo pipefail

but still there I can do

  ... | grep exrp || test $? -lt 2 | ...

Thanks for suggestion.

On Sun, Jan 14, 2018 at 8:57 AM, Paul Eggert <eggert <at> cs.ucla.edu> wrote:
> Vasyl Vavrychuk wrote:
>>
>> I would like to have an option to return success if nothing is found but
>> still return fail if error happens.
>
>
> You can use a shell command like this:
>
> grep PATTERN FILE
> test $? -lt 2
>
> I don't see the need for a special grep option to handle this problem.

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