On Thu, Feb 17, 2022 at 8:01 AM Ulrich Eckhardt
<ulrich.eckha...@base-42.de> wrote:
>
> I've implemented a `-p` flag for grep, which disables a behaviour that
> the exit status is used (abused?) to signal whether any match
> occurred.
The behaviour is POSIX.
> Now, for an example where it makes a difference. Consider a Bash script
> like this:
>
> # enable automatic error handling
> set -eo pipefail
> # check for string "issues" in a logfile
> cat logfile | grep issue | sort --unique
>
> If there are no issues in the logs, grep return exit code 1 and the
> shell interprets this as an error and exits itself.
>
Why do we need to implement a workaround in grep while you can
do this in shell to ignore the exit code of grep?
{ grep issue <logfile || :; } | sort --unique
> I've implemented that feature here, though it lacks tests yet:
> https://github.com/UlrichEckhardt/busybox/tree/grep-pipe-option
> Also, I'm currently trying to get the same feature into GNU grep as
> well, the long form `--pipe` is used there. I've also considered
> `--filter` (because it only filters) as alternative. I'm not fully
> happy with either one, maybe someone here comes up with a better
> suggestion.
I don't see the '--pipe' option in GNU grep manual
<https://www.gnu.org/software/grep/manual/grep.html>
and I don't think it would be needed considering that you can tell the
shell to ignore an exit code already.
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