From: Junio C Hamano <gitster@pobox.com>
To: Matthew DeVore <matvore@google.com>
Cc: git@vger.kernel.org, peff@peff.net, jonathantanmy@google.com,
jrn@google.com, sunshine@sunshineco.com, szeder.dev@gmail.com
Subject: Re: [PATCH v4 2/7] Documentation: add shell guidelines
Date: Fri, 05 Oct 2018 09:48:23 -0700 [thread overview]
Message-ID: <xmqq5zygwd9k.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: a45b646fced228e5a7fab4db7a35c1c6084e58d0.1538581868.git.matvore@google.com
Matthew DeVore <matvore@google.com> writes:
> Add the following guideline to Documentation/CodingGuidelines:
>
> &&, ||, and | should appear at the end of lines, not the
> beginning, and the \ line continuation character should be
> omitted
"should be omitted" sounds as if it is the norm to have such a
character, but it is not. The text in the actual patch body does a
much better job than this.
Perhaps
Break overlong lines after "&&", "||", and "|", not before
them; that way the command can continue to subsequent lines
without backslash at the end.
> And the following to t/README (since it is specific to writing tests):
>
> pipes and $(git ...) should be avoided when they swallow exit
> codes of Git processes
Good.
> Signed-off-by: Matthew DeVore <matvore@google.com>
> ---
> Documentation/CodingGuidelines | 18 ++++++++++++++++++
> t/README | 28 ++++++++++++++++++++++++++++
> 2 files changed, 46 insertions(+)
>
> diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines
> index 48aa4edfb..72967deb7 100644
> --- a/Documentation/CodingGuidelines
> +++ b/Documentation/CodingGuidelines
> @@ -118,6 +118,24 @@ For shell scripts specifically (not exhaustive):
> do this
> fi
>
> + - If a command sequence joined with && or || or | spans multiple
> + lines, put each command on a separate line and put && and || and |
> + operators at the end of each line, rather than the start. This
> + means you don't need to use \ to join lines, since the above
> + operators imply the sequence isn't finished.
Correct. Even though I wonder if we need to say the last sentence,
which is rather obvious, patch is already written and I do not see
much point editing this further.
> + (incorrect)
> + grep blob verify_pack_result \
> + | awk -f print_1.awk \
> + | sort >actual &&
> + ...
> +
> + (correct)
> + grep blob verify_pack_result |
> + awk -f print_1.awk |
> + sort >actual &&
> + ...
> +
> - We prefer "test" over "[ ... ]".
>
> - We do not write the noiseword "function" in front of shell
> diff --git a/t/README b/t/README
> index 85024aba6..9a71d5732 100644
> --- a/t/README
> +++ b/t/README
> @@ -466,6 +466,34 @@ And here are the "don'ts:"
> platform commands; just use '! cmd'. We are not in the business
> of verifying that the world given to us sanely works.
>
> + - Don't use Git upstream in the non-final position in a piped chain, as
> + in:
"upstream in the non-final position" is a bit redundant, isn't it?
- Don't feed the output of 'git' to a pipe, as in:
> +
> + git -C repo ls-files |
> + xargs -n 1 basename |
> + grep foo
> +
> + which will discard git's exit code and may mask a crash. In the
> + above example, all exit codes are ignored except grep's.
Good.
> + Instead, write the output of that command to a temporary
> + file with ">" or assign it to a variable with "x=$(git ...)" rather
> + than pipe it.
> +
> + - Don't use command substitution in a way that discards git's exit
> + code. When assigning to a variable, the exit code is not discarded,
> + e.g.:
> +
> + x=$(git cat-file -p $sha) &&
> + ...
> +
> + is OK because a crash in "git cat-file" will cause the "&&" chain
> + to fail, but:
> +
> + test "refs/heads/foo" = "$(git symbolic-ref HEAD)"
> +
> + is not OK and a crash in git could go undetected.
Good.
> - Don't use perl without spelling it as "$PERL_PATH". This is to help
> our friends on Windows where the platform Perl often adds CR before
> the end of line, and they bundle Git with a version of Perl that
next prev parent reply other threads:[~2018-10-05 16:48 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-15 0:02 [PATCH v1 0/2] Cleanup tests for test_cmp argument ordering and "|" placement Matthew DeVore
2018-09-15 0:02 ` [PATCH v1 1/2] t/*: fix pipe placement and remove \'s Matthew DeVore
2018-09-17 16:31 ` Jonathan Nieder
2018-09-17 21:47 ` Matthew DeVore
2018-09-15 0:02 ` [PATCH v1 2/2] t/*: fix ordering of expected/observed arguments Matthew DeVore
2018-09-17 12:56 ` Matthew DeVore
2018-09-15 15:55 ` [PATCH v1 0/2] Cleanup tests for test_cmp argument ordering and "|" placement Junio C Hamano
2018-09-17 22:24 ` [PATCH v2 0/6] Clean up tests for test_cmp arg ordering and pipe placement Matthew DeVore
2018-09-17 22:24 ` [PATCH v2 4/6] tests: Add linter check for pipe placement style Matthew DeVore
2018-09-18 0:34 ` Eric Sunshine
2018-09-19 17:39 ` Matthew DeVore
[not found] ` <cover.1537223021.git.matvore@google.com>
2018-09-17 22:24 ` [PATCH v2 1/6] CodingGuidelines: add shell piping guidelines Matthew DeVore
2018-09-18 0:16 ` Eric Sunshine
2018-09-19 2:11 ` Matthew DeVore
2018-09-19 12:36 ` Eric Sunshine
2018-09-19 14:24 ` Junio C Hamano
2018-09-19 20:06 ` Matthew DeVore
2018-09-17 22:24 ` [PATCH v2 2/6] tests: standardize pipe placement Matthew DeVore
2018-09-17 22:24 ` [PATCH v2 3/6] t/*: fix ordering of expected/observed arguments Matthew DeVore
2018-09-17 22:24 ` [PATCH v2 4/6] tests: add linter check for pipe placement style Matthew DeVore
2018-09-17 22:24 ` [PATCH v2 5/6] tests: split up pipes Matthew DeVore
2018-09-18 1:30 ` Eric Sunshine
2018-09-19 2:33 ` Matthew DeVore
2018-09-17 22:24 ` [PATCH v2 6/6] t9109-git-svn-props.sh: split up several pipes Matthew DeVore
2018-09-18 1:56 ` Eric Sunshine
2018-09-19 2:56 ` Matthew DeVore
2018-09-19 12:50 ` Eric Sunshine
2018-09-19 18:43 ` Matthew DeVore
2018-09-21 1:43 ` [PATCH v3 0/5] Clean up tests for test_cmp arg ordering and pipe placement Matthew DeVore
2018-09-21 1:43 ` [PATCH v3 1/5] CodingGuidelines: add shell piping guidelines Matthew DeVore
2018-09-21 2:06 ` Eric Sunshine
2018-09-21 21:03 ` Matthew DeVore
2018-09-24 21:03 ` SZEDER Gábor
2018-09-25 21:58 ` Matthew DeVore
2018-09-27 21:18 ` SZEDER Gábor
2018-10-01 23:07 ` Matthew DeVore
2018-09-21 1:43 ` [PATCH v3 2/5] tests: standardize pipe placement Matthew DeVore
2018-09-21 1:43 ` [PATCH v3 3/5] t/*: fix ordering of expected/observed arguments Matthew DeVore
2018-09-21 1:43 ` [PATCH v3 4/5] tests: don't swallow Git errors upstream of pipes Matthew DeVore
2018-09-21 1:43 ` [PATCH v3 5/5] t9109: " Matthew DeVore
2018-10-03 16:25 ` [PATCH v4 0/7] Clean up tests for test_cmp arg ordering and pipe placement Matthew DeVore
2018-10-03 16:25 ` [PATCH v4 1/7] t/README: reformat Do, Don't, Keep in mind lists Matthew DeVore
2018-10-05 6:15 ` Junio C Hamano
2018-10-05 14:57 ` Matthew DeVore
2018-10-03 16:26 ` [PATCH v4 2/7] Documentation: add shell guidelines Matthew DeVore
2018-10-05 16:48 ` Junio C Hamano [this message]
2018-10-05 18:21 ` Matthew DeVore
2018-10-03 16:26 ` [PATCH v4 3/7] tests: standardize pipe placement Matthew DeVore
2018-10-03 16:26 ` [PATCH v4 4/7] t/*: fix ordering of expected/observed arguments Matthew DeVore
2018-10-03 16:26 ` [PATCH v4 5/7] tests: don't swallow Git errors upstream of pipes Matthew DeVore
2018-10-05 16:48 ` Junio C Hamano
2018-10-05 17:54 ` Matthew DeVore
2018-10-05 18:12 ` Matthew DeVore
2018-10-03 16:26 ` [PATCH v4 6/7] t9109: " Matthew DeVore
2018-10-03 16:26 ` [PATCH v4 7/7] tests: order arguments to git-rev-list properly Matthew DeVore
2018-10-03 16:33 ` Matthew DeVore
2018-10-05 8:16 ` Junio C Hamano
2018-10-05 21:54 ` [PATCH v5 0/7] subject: Clean up tests for test_cmp arg ordering and pipe placement Matthew DeVore
2018-10-05 21:54 ` [PATCH v5 1/7] t/README: reformat Do, Don't, Keep in mind lists Matthew DeVore
2018-10-05 21:54 ` [PATCH v5 2/7] Documentation: add shell guidelines Matthew DeVore
2018-10-05 21:54 ` [PATCH v5 3/7] tests: standardize pipe placement Matthew DeVore
2018-10-05 21:54 ` [PATCH v5 4/7] t/*: fix ordering of expected/observed arguments Matthew DeVore
2018-10-05 21:54 ` [PATCH v5 5/7] tests: don't swallow Git errors upstream of pipes Matthew DeVore
2018-10-05 21:54 ` [PATCH v5 6/7] t9109: " Matthew DeVore
2018-10-05 21:54 ` [PATCH v5 7/7] tests: order arguments to git-rev-list properly Matthew DeVore
2018-10-06 23:53 ` [PATCH v5 0/7] subject: Clean up tests for test_cmp arg ordering and pipe placement Junio C Hamano
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