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From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: Johannes Sixt <j6t@kdbg.org>
Cc: "Philippe Blain" <levraiphilippeblain@gmail.com>,
	"René Scharfe" <l.s.r@web.de>,
	"Git Mailing List" <git@vger.kernel.org>
Subject: Re: [PATCH] t3920: don't ignore errors of more than one command with `|| true`
Date: Tue, 22 Nov 2022 23:57:20 +0100	[thread overview]
Message-ID: <221123.86ilj6a8ux.gmgdl@evledraar.gmail.com> (raw)
In-Reply-To: <271dd9e6-3575-a46f-4c92-fa202aaf95d7@kdbg.org>


On Tue, Nov 22 2022, Johannes Sixt wrote:

> Am 22.11.22 um 23:24 schrieb Ævar Arnfjörð Bjarmason:
>> On Mon, Nov 21 2022, Johannes Sixt wrote:
>>> -	grep 'Body' .crlf-message-$branch.txt >.crlf-body-$branch.txt || true &&
>>> +	{ grep 'Body' .crlf-message-$branch.txt >.crlf-body-$branch.txt || true; } &&
>> 
>> Any reason not to make this:
>> 
>> 	-       grep 'Body' .crlf-message-$branch.txt >.crlf-body-$branch.txt || true &&
>> 	+       sed -ne '/Body/p' <.crlf-message-$branch.txt >.crlf-body-$branch.txt &&
>> 
>> ?
>
> Yes: I have tested my version, but not this one.

I don't find that too surprising, as unless there's a discussion of "I
tried xyz, but it didn't work, so..." a submitted patch is unlikely to
have tried various alternatives for such a trivial fix, but just gone
with whatever the author tried first.

But in case it wasn't clear, the implied suggestion is that unless there
is a good reason to introduce a pattern of:

	 { <cmd> in >out || true; } &&

That we should use another suitable command with the simpler use of:

	 <cmd2> <in >out &&

If the result is equivalent, as subsequent maintainers won't need to
puzzle over the seemingly odd pattern.

We have that "sed -n -e" in somewhat wide use:

	$ git grep 'sed (-n -e|-ne).*/p.*&&' | wc -l
	54

The only existing occurance of this "grep but ignore the exit code" I
could find was:

	t/t9001-send-email.sh:  { grep '^X-Mailer:' out || :; } >mailer &&

For which we can also:

	-       { grep '^X-Mailer:' out || :; } >mailer &&
	+       sed -ne '/^X-Mailer:/p' <out >mailer &&

And which I'd think would be great to have in a re-roll, i.e. "here's
these two cases where a grep-but-dont-care-about-the-exit-code could be
replaced by sed -ne".

But if re-testing this is tedious etc. I don't mind if it goes in as-is,
but then I'd think we could safely emulate the t9001-send-email.sh
pattern of using ":" instead of "true"; we don't need to invoke another
process just to ignore the exit code.




  reply	other threads:[~2022-11-22 23:05 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-21 17:58 [PATCH] t3920: don't ignore errors of more than one command with `|| true` Johannes Sixt
2022-11-21 22:56 ` René Scharfe
2022-11-22  0:53   ` Junio C Hamano
2022-11-22 18:28 ` Philippe Blain
2022-11-22 22:24 ` Ævar Arnfjörð Bjarmason
2022-11-22 22:37   ` Johannes Sixt
2022-11-22 22:57     ` Ævar Arnfjörð Bjarmason [this message]
2022-11-23  0:55       ` Junio C Hamano
2022-12-02 16:51 ` [PATCH 2/1] t3920: support CR-eating grep René Scharfe
2022-12-02 23:14   ` Philippe Blain
2022-12-03  7:09     ` René Scharfe
2022-12-02 23:32   ` Eric Sunshine
2022-12-03  7:12     ` René Scharfe
2022-12-05  1:08   ` Junio C Hamano
2022-12-05  8:28     ` René Scharfe
2022-12-05  9:32       ` Junio C Hamano
2022-12-05 10:43         ` René Scharfe
2022-12-02 16:51 ` [PATCH 3/1] t3920: simplify redirection of loop output René Scharfe
2022-12-02 16:51 ` [PATCH 4/1] t3920: replace two cats with a tee René Scharfe
2022-12-03  5:09   ` Eric Sunshine
2022-12-03  8:43     ` René Scharfe
2022-12-03 12:53       ` Ævar Arnfjörð Bjarmason
2022-12-03 17:22         ` René Scharfe
2022-12-04  9:34           ` Ævar Arnfjörð Bjarmason
2022-12-04 16:39             ` Eric Sunshine

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