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From: Matthew DeVore <matvore@google.com>
To: git@vger.kernel.org
Cc: Matthew DeVore <matvore@google.com>,
	peff@peff.net, jonathantanmy@google.com, gitster@pobox.com,
	jrn@google.com
Subject: [PATCH v2 1/6] CodingGuidelines: add shell piping guidelines
Date: Mon, 17 Sep 2018 15:24:17 -0700	[thread overview]
Message-ID: <c625bfe2205d51b3158ef71e4bf472708642c146.1537223021.git.matvore@google.com> (raw)
In-Reply-To: <cover.1537223021.git.matvore@google.com>

Add two guidelines:

 - pipe characters should appear at the end of lines, and not cause
   indentation
 - pipes should be avoided when they swallow exit codes that can
   potentially fail
---
 Documentation/CodingGuidelines | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines
index 48aa4edfb..7f903c1aa 100644
--- a/Documentation/CodingGuidelines
+++ b/Documentation/CodingGuidelines
@@ -163,6 +163,35 @@ For shell scripts specifically (not exhaustive):
 
    does not have such a problem.
 
+ - In a piped sequence which spans multiple lines, put each statement
+   on a separate line and put pipes on the end of each line, rather
+   than the start. This means you don't need to use \ to join lines,
+   since | implies a join already. Also, do not indent subsequent
+   lines; if you need a sequence to visually stand apart from the
+   surrounding code, use a blank line before and/or after the piped
+   sequence.
+
+	(incorrect)
+	echo '...' > expected
+	git ls-files -s file.1 file.2 file.3 file.4 file.5 \
+		| awk '{print $1}' \
+		| sort >observed
+	test_cmp expected actual
+
+	(correct)
+	echo '...' > expected
+
+	git ls-files -s file.1 file.2 file.3 file.4 file.5 |
+	awk '{print $1}' |
+	sort >observed
+
+	test_cmp expected actual
+
+ - In a pipe, any non-zero exit codes returned by processes besides
+   the last will be ignored. If there is any possibility some
+   non-final command in the pipe will raise an error, prefer writing
+   the output of that command to a temporary file with '>' rather than
+   pipe it.
 
 For C programs:
 
-- 
2.19.0.444.g18242da7ef-goog


  parent reply	other threads:[~2018-09-17 22:24 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   ` Matthew DeVore [this message]
2018-09-18  0:16     ` [PATCH v2 1/6] CodingGuidelines: add shell piping guidelines 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
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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