1GIT-INTERPRET-TRAILERS(1) Git Manual GIT-INTERPRET-TRAILERS(1)
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6 git-interpret-trailers - Add or parse structured information in commit
7 messages
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10 git interpret-trailers [--in-place] [--trim-empty]
11 [(--trailer (<key>|<keyAlias>)[(=|:)<value>])...]
12 [--parse] [<file>...]
13
15 Add or parse trailer lines that look similar to RFC 822 e-mail headers,
16 at the end of the otherwise free-form part of a commit message. For
17 example, in the following commit message
18 subject
20 Lorem ipsum dolor sit amet, consectetur adipiscing elit.
22 Signed-off-by: Alice <alice@example.com>
24 Signed-off-by: Bob <bob@example.com>
25 the last two lines starting with "Signed-off-by" are trailers.
27 This command reads commit messages from either the <file> arguments or
29 the standard input if no <file> is specified. If --parse is specified,
30 the output consists of the parsed trailers coming from the input,
31 without influencing them with any command line options or configuration
32 variables.
33 Otherwise, this command applies trailer.* configuration variables
35 (which could potentially add new trailers, as well as reposition them),
36 as well as any command line arguments that can override configuration
37 variables (such as --trailer=... which could also add new trailers), to
38 each input file. The result is emitted on the standard output.
39 This command can also operate on the output of git-format-patch(1),
41 which is more elaborate than a plain commit message. Namely, such
42 output includes a commit message (as above), a "---" divider line, and
43 a patch part. For these inputs, the divider and patch parts are not
44 modified by this command and are emitted as is on the output, unless
45 --no-divider is specified.
46 Some configuration variables control the way the --trailer arguments
48 are applied to each input and the way any existing trailer in the input
49 is changed. They also make it possible to automatically add some
50 trailers.
51 By default, a <key>=<value> or <key>:<value> argument given using
53 --trailer will be appended after the existing trailers only if the last
54 trailer has a different (<key>, <value>) pair (or if there is no
55 existing trailer). The <key> and <value> parts will be trimmed to
56 remove starting and trailing whitespace, and the resulting trimmed
57 <key> and <value> will appear in the output like this:
58 key: value
60 This means that the trimmed <key> and <value> will be separated by ': '
62 (one colon followed by one space).
63 For convenience, a <keyAlias> can be configured to make using --trailer
65 shorter to type on the command line. This can be configured using the
66 trailer.<keyAlias>.key configuration variable. The <keyAlias> must be a
67 prefix of the full <key> string, although case sensitivity does not
68 matter. For example, if you have
69 trailer.sign.key "Signed-off-by: "
71 in your configuration, you only need to specify --trailer="sign: foo"
73 on the command line instead of --trailer="Signed-off-by: foo".
74 By default the new trailer will appear at the end of all the existing
76 trailers. If there is no existing trailer, the new trailer will appear
77 at the end of the input. A blank line will be added before the new
78 trailer if there isn’t one already.
79 Existing trailers are extracted from the input by looking for a group
81 of one or more lines that (i) is all trailers, or (ii) contains at
82 least one Git-generated or user-configured trailer and consists of at
83 least 25% trailers. The group must be preceded by one or more empty (or
84 whitespace-only) lines. The group must either be at the end of the
85 input or be the last non-whitespace lines before a line that starts
86 with --- (followed by a space or the end of the line).
87 When reading trailers, there can be no whitespace before or inside the
89 <key>, but any number of regular space and tab characters are allowed
90 between the <key> and the separator. There can be whitespaces before,
91 inside or after the <value>. The <value> may be split over multiple
92 lines with each subsequent line starting with at least one whitespace,
93 like the "folding" in RFC 822. Example:
94 key: This is a very long value, with spaces and
96 newlines in it.
97 Note that trailers do not follow (nor are they intended to follow) many
99 of the rules for RFC 822 headers. For example they do not follow the
100 encoding rule.
101
103 --in-place
104 Edit the files in place.
105 --trim-empty
107 If the <value> part of any trailer contains only whitespace, the
108 whole trailer will be removed from the output. This applies to
109 existing trailers as well as new trailers.
110 --trailer <key>[(=|:)<value>]
112 Specify a (<key>, <value>) pair that should be applied as a trailer
113 to the inputs. See the description of this command.
114 --where <placement>, --no-where
116 Specify where all new trailers will be added. A setting provided
117 with --where overrides the trailer.where and any applicable
118 trailer.<keyAlias>.where configuration variables and applies to all
119 --trailer options until the next occurrence of --where or
120 --no-where. Upon encountering --no-where, clear the effect of any
121 previous use of --where, such that the relevant configuration
122 variables are no longer overridden. Possible placements are after,
123 before, end or start.
124 --if-exists <action>, --no-if-exists
126 Specify what action will be performed when there is already at
127 least one trailer with the same <key> in the input. A setting
128 provided with --if-exists overrides the trailer.ifExists and any
129 applicable trailer.<keyAlias>.ifExists configuration variables and
130 applies to all --trailer options until the next occurrence of
131 --if-exists or --no-if-exists. Upon encountering '--no-if-exists,
132 clear the effect of any previous use of '--if-exists, such that the
133 relevant configuration variables are no longer overridden. Possible
134 actions are addIfDifferent, addIfDifferentNeighbor, add, replace
135 and doNothing.
136 --if-missing <action>, --no-if-missing
138 Specify what action will be performed when there is no other
139 trailer with the same <key> in the input. A setting provided with
140 --if-missing overrides the trailer.ifMissing and any applicable
141 trailer.<keyAlias>.ifMissing configuration variables and applies to
142 all --trailer options until the next occurrence of --if-missing or
143 --no-if-missing. Upon encountering '--no-if-missing, clear the
144 effect of any previous use of '--if-missing, such that the relevant
145 configuration variables are no longer overridden. Possible actions
146 are doNothing or add.
147 --only-trailers
149 Output only the trailers, not any other parts of the input.
150 --only-input
152 Output only trailers that exist in the input; do not add any from
153 the command-line or by applying trailer.* configuration variables.
154 --unfold
156 If a trailer has a value that runs over multiple lines (aka
157 "folded"), reformat the value into a single line.
158 --parse
160 A convenience alias for --only-trailers --only-input --unfold. This
161 makes it easier to only see the trailers coming from the input
162 without influencing them with any command line options or
163 configuration variables, while also making the output
164 machine-friendly with --unfold.
165 --no-divider
167 Do not treat --- as the end of the commit message. Use this when
168 you know your input contains just the commit message itself (and
169 not an email or the output of git format-patch).
170
172 trailer.separators
173 This option tells which characters are recognized as trailer
174 separators. By default only : is recognized as a trailer separator,
175 except that = is always accepted on the command line for
176 compatibility with other git commands.
177 The first character given by this option will be the default
179 character used when another separator is not specified in the
180 config for this trailer.
181 For example, if the value for this option is "%=$", then only lines
183 using the format <key><sep><value> with <sep> containing %, = or $
184 and then spaces will be considered trailers. And % will be the
185 default separator used, so by default trailers will appear like:
186 <key>% <value> (one percent sign and one space will appear between
187 the key and the value).
188 trailer.where
190 This option tells where a new trailer will be added.
191 This can be end, which is the default, start, after or before.
193 If it is end, then each new trailer will appear at the end of the
195 existing trailers.
196 If it is start, then each new trailer will appear at the start,
198 instead of the end, of the existing trailers.
199 If it is after, then each new trailer will appear just after the
201 last trailer with the same <key>.
202 If it is before, then each new trailer will appear just before the
204 first trailer with the same <key>.
205 trailer.ifexists
207 This option makes it possible to choose what action will be
208 performed when there is already at least one trailer with the same
209 <key> in the input.
210 The valid values for this option are: addIfDifferentNeighbor (this
212 is the default), addIfDifferent, add, replace or doNothing.
213 With addIfDifferentNeighbor, a new trailer will be added only if no
215 trailer with the same (<key>, <value>) pair is above or below the
216 line where the new trailer will be added.
217 With addIfDifferent, a new trailer will be added only if no trailer
219 with the same (<key>, <value>) pair is already in the input.
220 With add, a new trailer will be added, even if some trailers with
222 the same (<key>, <value>) pair are already in the input.
223 With replace, an existing trailer with the same <key> will be
225 deleted and the new trailer will be added. The deleted trailer will
226 be the closest one (with the same <key>) to the place where the new
227 one will be added.
228 With doNothing, nothing will be done; that is no new trailer will
230 be added if there is already one with the same <key> in the input.
231 trailer.ifmissing
233 This option makes it possible to choose what action will be
234 performed when there is not yet any trailer with the same <key> in
235 the input.
236 The valid values for this option are: add (this is the default) and
238 doNothing.
239 With add, a new trailer will be added.
241 With doNothing, nothing will be done.
243 trailer.<keyAlias>.key
245 Defines a <keyAlias> for the <key>. The <keyAlias> must be a prefix
246 (case does not matter) of the <key>. For example, in git config
247 trailer.ack.key "Acked-by" the "Acked-by" is the <key> and the
248 "ack" is the <keyAlias>. This configuration allows the shorter
249 --trailer "ack:..." invocation on the command line using the "ack"
250 <keyAlias> instead of the longer --trailer "Acked-by:...".
251 At the end of the <key>, a separator can appear and then some space
253 characters. By default the only valid separator is :, but this can
254 be changed using the trailer.separators config variable.
255 If there is a separator in the key, then it overrides the default
257 separator when adding the trailer.
258 trailer.<keyAlias>.where
260 This option takes the same values as the trailer.where
261 configuration variable and it overrides what is specified by that
262 option for trailers with the specified <keyAlias>.
263 trailer.<keyAlias>.ifexists
265 This option takes the same values as the trailer.ifexists
266 configuration variable and it overrides what is specified by that
267 option for trailers with the specified <keyAlias>.
268 trailer.<keyAlias>.ifmissing
270 This option takes the same values as the trailer.ifmissing
271 configuration variable and it overrides what is specified by that
272 option for trailers with the specified <keyAlias>.
273 trailer.<keyAlias>.command
275 Deprecated in favor of trailer.<keyAlias>.cmd. This option behaves
276 in the same way as trailer.<keyAlias>.cmd, except that it doesn’t
277 pass anything as argument to the specified command. Instead the
278 first occurrence of substring $ARG is replaced by the <value> that
279 would be passed as argument.
280 Note that $ARG in the user’s command is only replaced once and that
282 the original way of replacing $ARG is not safe.
283 When both trailer.<keyAlias>.cmd and trailer.<keyAlias>.command are
285 given for the same <keyAlias>, trailer.<keyAlias>.cmd is used and
286 trailer.<keyAlias>.command is ignored.
287 trailer.<keyAlias>.cmd
289 This option can be used to specify a shell command that will be
290 called once to automatically add a trailer with the specified
291 <keyAlias>, and then called each time a --trailer
292 <keyAlias>=<value> argument is specified to modify the <value> of
293 the trailer that this option would produce.
294 When the specified command is first called to add a trailer with
296 the specified <keyAlias>, the behavior is as if a special --trailer
297 <keyAlias>=<value> argument was added at the beginning of the "git
298 interpret-trailers" command, where <value> is taken to be the
299 standard output of the command with any leading and trailing
300 whitespace trimmed off.
301 If some --trailer <keyAlias>=<value> arguments are also passed on
303 the command line, the command is called again once for each of
304 these arguments with the same <keyAlias>. And the <value> part of
305 these arguments, if any, will be passed to the command as its first
306 argument. This way the command can produce a <value> computed from
307 the <value> passed in the --trailer <keyAlias>=<value> argument.
308
310 • Configure a sign trailer with a Signed-off-by key, and then add two
311 of these trailers to a commit message file:
312 $ git config trailer.sign.key "Signed-off-by"
314 $ cat msg.txt
315 subject
316 body text
318 $ git interpret-trailers --trailer 'sign: Alice <alice@example.com>' --trailer 'sign: Bob <bob@example.com>' <msg.txt
319 subject
320 body text
322 Signed-off-by: Alice <alice@example.com>
324 Signed-off-by: Bob <bob@example.com>
325 • Use the --in-place option to edit a commit message file in place:
327 $ cat msg.txt
329 subject
330 body text
332 Signed-off-by: Bob <bob@example.com>
334 $ git interpret-trailers --trailer 'Acked-by: Alice <alice@example.com>' --in-place msg.txt
335 $ cat msg.txt
336 subject
337 body text
339 Signed-off-by: Bob <bob@example.com>
341 Acked-by: Alice <alice@example.com>
342 • Extract the last commit as a patch, and add a Cc and a Reviewed-by
344 trailer to it:
345 $ git format-patch -1
347 0001-foo.patch
348 $ git interpret-trailers --trailer 'Cc: Alice <alice@example.com>' --trailer 'Reviewed-by: Bob <bob@example.com>' 0001-foo.patch >0001-bar.patch
349 • Configure a sign trailer with a command to automatically add a
351 'Signed-off-by: ' with the author information only if there is no
352 'Signed-off-by: ' already, and show how it works:
353 $ cat msg1.txt
355 subject
356 body text
358 $ git config trailer.sign.key "Signed-off-by: "
359 $ git config trailer.sign.ifmissing add
360 $ git config trailer.sign.ifexists doNothing
361 $ git config trailer.sign.cmd 'echo "$(git config user.name) <$(git config user.email)>"'
362 $ git interpret-trailers --trailer sign <msg1.txt
363 subject
364 body text
366 Signed-off-by: Bob <bob@example.com>
368 $ cat msg2.txt
369 subject
370 body text
372 Signed-off-by: Alice <alice@example.com>
374 $ git interpret-trailers --trailer sign <msg2.txt
375 subject
376 body text
378 Signed-off-by: Alice <alice@example.com>
380 • Configure a fix trailer with a key that contains a # and no space
382 after this character, and show how it works:
383 $ git config trailer.separators ":#"
385 $ git config trailer.fix.key "Fix #"
386 $ echo "subject" | git interpret-trailers --trailer fix=42
387 subject
388 Fix #42
390 • Configure a help trailer with a cmd use a script glog-find-author
392 which search specified author identity from git log in git
393 repository and show how it works:
394 $ cat ~/bin/glog-find-author
396 #!/bin/sh
397 test -n "$1" && git log --author="$1" --pretty="%an <%ae>" -1 || true
398 $ cat msg.txt
399 subject
400 body text
402 $ git config trailer.help.key "Helped-by: "
403 $ git config trailer.help.ifExists "addIfDifferentNeighbor"
404 $ git config trailer.help.cmd "~/bin/glog-find-author"
405 $ git interpret-trailers --trailer="help:Junio" --trailer="help:Couder" <msg.txt
406 subject
407 body text
409 Helped-by: Junio C Hamano <gitster@pobox.com>
411 Helped-by: Christian Couder <christian.couder@gmail.com>
412 • Configure a ref trailer with a cmd use a script glog-grep to grep
414 last relevant commit from git log in the git repository and show
415 how it works:
416 $ cat ~/bin/glog-grep
418 #!/bin/sh
419 test -n "$1" && git log --grep "$1" --pretty=reference -1 || true
420 $ cat msg.txt
421 subject
422 body text
424 $ git config trailer.ref.key "Reference-to: "
425 $ git config trailer.ref.ifExists "replace"
426 $ git config trailer.ref.cmd "~/bin/glog-grep"
427 $ git interpret-trailers --trailer="ref:Add copyright notices." <msg.txt
428 subject
429 body text
431 Reference-to: 8bc9a0c769 (Add copyright notices., 2005-04-07)
433 • Configure a see trailer with a command to show the subject of a
435 commit that is related, and show how it works:
436 $ cat msg.txt
438 subject
439 body text
441 see: HEAD~2
443 $ cat ~/bin/glog-ref
444 #!/bin/sh
445 git log -1 --oneline --format="%h (%s)" --abbrev-commit --abbrev=14
446 $ git config trailer.see.key "See-also: "
447 $ git config trailer.see.ifExists "replace"
448 $ git config trailer.see.ifMissing "doNothing"
449 $ git config trailer.see.cmd "glog-ref"
450 $ git interpret-trailers --trailer=see <msg.txt
451 subject
452 body text
454 See-also: fe3187489d69c4 (subject of related commit)
456 • Configure a commit template with some trailers with empty values
458 (using sed to show and keep the trailing spaces at the end of the
459 trailers), then configure a commit-msg hook that uses git
460 interpret-trailers to remove trailers with empty values and to add
461 a git-version trailer:
462 $ cat temp.txt
464 ***subject***
465 ***message***
467 Fixes: Z
469 Cc: Z
470 Reviewed-by: Z
471 Signed-off-by: Z
472 $ sed -e 's/ Z$/ /' temp.txt > commit_template.txt
473 $ git config commit.template commit_template.txt
474 $ cat .git/hooks/commit-msg
475 #!/bin/sh
476 git interpret-trailers --trim-empty --trailer "git-version: \$(git describe)" "\$1" > "\$1.new"
477 mv "\$1.new" "\$1"
478 $ chmod +x .git/hooks/commit-msg
479
481 git-commit(1), git-format-patch(1), git-config(1)
482
484 Part of the git(1) suite
485Git 2.43.0 11/20/2023 GIT-INTERPRET-TRAILERS(1)