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Re: Additional "grep" parameter to change the exit code from 1 to 0, eve

From: Jim Meyering
Subject: Re: Additional "grep" parameter to change the exit code from 1 to 0, even if grep doesn't find pattern
Date: Fri, 02 Sep 2011 15:21:28 +0200

Robert wrote:

> Hello everybody,
> 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.


    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.

> In bash programming I often use the "trap" command with the "ERR"
> parameter. "ERR" reacts when a normal command like "grep", "mount", etc.
> produces an non-zero exit code. "ERR" is similar to the bash "set -e" or
> "set -o errexit" option.
> My thought is, that NOT finding a pattern, is not always a reason to
> consider the result as an error or the command being unsuccessfully. In
> my opinion, it would just be a handy way to avoid using "awk" or "sed",
> which produce exit code 0, when NOT finding a pattern.
> Just an idea... :)
> Kind regards,
> Robert S.

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