doc/interpret-trailers: fix "the this" typo
[git/git.git] / Documentation / git-interpret-trailers.txt
1 git-interpret-trailers(1)
2 =========================
3
4 NAME
5 ----
6 git-interpret-trailers - add or parse structured information in commit messages
7
8 SYNOPSIS
9 --------
10 [verse]
11 'git interpret-trailers' [options] [(--trailer <token>[(=|:)<value>])...] [<file>...]
12 'git interpret-trailers' [options] [--parse] [<file>...]
13
14 DESCRIPTION
15 -----------
16 Help parsing or adding 'trailers' lines, that look similar to RFC 822 e-mail
17 headers, at the end of the otherwise free-form part of a commit
18 message.
19
20 This command reads some patches or commit messages from either the
21 <file> arguments or the standard input if no <file> is specified. If
22 `--parse` is specified, the output consists of the parsed trailers.
23
24 Otherwise, this command applies the arguments passed using the
25 `--trailer` option, if any, to the commit message part of each input
26 file. The result is emitted on the standard output.
27
28 Some configuration variables control the way the `--trailer` arguments
29 are applied to each commit message and the way any existing trailer in
30 the commit message is changed. They also make it possible to
31 automatically add some trailers.
32
33 By default, a '<token>=<value>' or '<token>:<value>' argument given
34 using `--trailer` will be appended after the existing trailers only if
35 the last trailer has a different (<token>, <value>) pair (or if there
36 is no existing trailer). The <token> and <value> parts will be trimmed
37 to remove starting and trailing whitespace, and the resulting trimmed
38 <token> and <value> will appear in the message like this:
39
40 ------------------------------------------------
41 token: value
42 ------------------------------------------------
43
44 This means that the trimmed <token> and <value> will be separated by
45 `': '` (one colon followed by one space).
46
47 By default the new trailer will appear at the end of all the existing
48 trailers. If there is no existing trailer, the new trailer will appear
49 after the commit message part of the output, and, if there is no line
50 with only spaces at the end of the commit message part, one blank line
51 will be added before the new trailer.
52
53 Existing trailers are extracted from the input message by looking for
54 a group of one or more lines that (i) are all trailers, or (ii) contains at
55 least one Git-generated or user-configured trailer and consists of at
56 least 25% trailers.
57 The group must be preceded by one or more empty (or whitespace-only) lines.
58 The group must either be at the end of the message or be the last
59 non-whitespace lines before a line that starts with '---'. Such three
60 minus signs start the patch part of the message.
61
62 When reading trailers, there can be whitespaces after the
63 token, the separator and the value. There can also be whitespaces
64 inside the token and the value. The value may be split over multiple lines with
65 each subsequent line starting with whitespace, like the "folding" in RFC 822.
66
67 Note that 'trailers' do not follow and are not intended to follow many
68 rules for RFC 822 headers. For example they do not follow
69 the encoding rules and probably many other rules.
70
71 OPTIONS
72 -------
73 --in-place::
74 Edit the files in place.
75
76 --trim-empty::
77 If the <value> part of any trailer contains only whitespace,
78 the whole trailer will be removed from the resulting message.
79 This applies to existing trailers as well as new trailers.
80
81 --trailer <token>[(=|:)<value>]::
82 Specify a (<token>, <value>) pair that should be applied as a
83 trailer to the input messages. See the description of this
84 command.
85
86 --only-trailers::
87 Output only the trailers, not any other parts of the input.
88
89 --only-input::
90 Output only trailers that exist in the input; do not add any
91 from the command-line or by following configured `trailer.*`
92 rules.
93
94 --unfold::
95 Remove any whitespace-continuation in trailers, so that each
96 trailer appears on a line by itself with its full content.
97
98 --parse::
99 A convenience alias for `--only-trailers --only-input
100 --unfold`.
101
102 CONFIGURATION VARIABLES
103 -----------------------
104
105 trailer.separators::
106 This option tells which characters are recognized as trailer
107 separators. By default only ':' is recognized as a trailer
108 separator, except that '=' is always accepted on the command
109 line for compatibility with other git commands.
110 +
111 The first character given by this option will be the default character
112 used when another separator is not specified in the config for this
113 trailer.
114 +
115 For example, if the value for this option is "%=$", then only lines
116 using the format '<token><sep><value>' with <sep> containing '%', '='
117 or '$' and then spaces will be considered trailers. And '%' will be
118 the default separator used, so by default trailers will appear like:
119 '<token>% <value>' (one percent sign and one space will appear between
120 the token and the value).
121
122 trailer.where::
123 This option tells where a new trailer will be added.
124 +
125 This can be `end`, which is the default, `start`, `after` or `before`.
126 +
127 If it is `end`, then each new trailer will appear at the end of the
128 existing trailers.
129 +
130 If it is `start`, then each new trailer will appear at the start,
131 instead of the end, of the existing trailers.
132 +
133 If it is `after`, then each new trailer will appear just after the
134 last trailer with the same <token>.
135 +
136 If it is `before`, then each new trailer will appear just before the
137 first trailer with the same <token>.
138
139 trailer.ifexists::
140 This option makes it possible to choose what action will be
141 performed when there is already at least one trailer with the
142 same <token> in the message.
143 +
144 The valid values for this option are: `addIfDifferentNeighbor` (this
145 is the default), `addIfDifferent`, `add`, `replace` or `doNothing`.
146 +
147 With `addIfDifferentNeighbor`, a new trailer will be added only if no
148 trailer with the same (<token>, <value>) pair is above or below the line
149 where the new trailer will be added.
150 +
151 With `addIfDifferent`, a new trailer will be added only if no trailer
152 with the same (<token>, <value>) pair is already in the message.
153 +
154 With `add`, a new trailer will be added, even if some trailers with
155 the same (<token>, <value>) pair are already in the message.
156 +
157 With `replace`, an existing trailer with the same <token> will be
158 deleted and the new trailer will be added. The deleted trailer will be
159 the closest one (with the same <token>) to the place where the new one
160 will be added.
161 +
162 With `doNothing`, nothing will be done; that is no new trailer will be
163 added if there is already one with the same <token> in the message.
164
165 trailer.ifmissing::
166 This option makes it possible to choose what action will be
167 performed when there is not yet any trailer with the same
168 <token> in the message.
169 +
170 The valid values for this option are: `add` (this is the default) and
171 `doNothing`.
172 +
173 With `add`, a new trailer will be added.
174 +
175 With `doNothing`, nothing will be done.
176
177 trailer.<token>.key::
178 This `key` will be used instead of <token> in the trailer. At
179 the end of this key, a separator can appear and then some
180 space characters. By default the only valid separator is ':',
181 but this can be changed using the `trailer.separators` config
182 variable.
183 +
184 If there is a separator, then the key will be used instead of both the
185 <token> and the default separator when adding the trailer.
186
187 trailer.<token>.where::
188 This option takes the same values as the 'trailer.where'
189 configuration variable and it overrides what is specified by
190 that option for trailers with the specified <token>.
191
192 trailer.<token>.ifexist::
193 This option takes the same values as the 'trailer.ifexist'
194 configuration variable and it overrides what is specified by
195 that option for trailers with the specified <token>.
196
197 trailer.<token>.ifmissing::
198 This option takes the same values as the 'trailer.ifmissing'
199 configuration variable and it overrides what is specified by
200 that option for trailers with the specified <token>.
201
202 trailer.<token>.command::
203 This option can be used to specify a shell command that will
204 be called to automatically add or modify a trailer with the
205 specified <token>.
206 +
207 When this option is specified, the behavior is as if a special
208 '<token>=<value>' argument were added at the beginning of the command
209 line, where <value> is taken to be the standard output of the
210 specified command with any leading and trailing whitespace trimmed
211 off.
212 +
213 If the command contains the `$ARG` string, this string will be
214 replaced with the <value> part of an existing trailer with the same
215 <token>, if any, before the command is launched.
216 +
217 If some '<token>=<value>' arguments are also passed on the command
218 line, when a 'trailer.<token>.command' is configured, the command will
219 also be executed for each of these arguments. And the <value> part of
220 these arguments, if any, will be used to replace the `$ARG` string in
221 the command.
222
223 EXAMPLES
224 --------
225
226 * Configure a 'sign' trailer with a 'Signed-off-by' key, and then
227 add two of these trailers to a message:
228 +
229 ------------
230 $ git config trailer.sign.key "Signed-off-by"
231 $ cat msg.txt
232 subject
233
234 message
235 $ cat msg.txt | git interpret-trailers --trailer 'sign: Alice <alice@example.com>' --trailer 'sign: Bob <bob@example.com>'
236 subject
237
238 message
239
240 Signed-off-by: Alice <alice@example.com>
241 Signed-off-by: Bob <bob@example.com>
242 ------------
243
244 * Use the `--in-place` option to edit a message file in place:
245 +
246 ------------
247 $ cat msg.txt
248 subject
249
250 message
251
252 Signed-off-by: Bob <bob@example.com>
253 $ git interpret-trailers --trailer 'Acked-by: Alice <alice@example.com>' --in-place msg.txt
254 $ cat msg.txt
255 subject
256
257 message
258
259 Signed-off-by: Bob <bob@example.com>
260 Acked-by: Alice <alice@example.com>
261 ------------
262
263 * Extract the last commit as a patch, and add a 'Cc' and a
264 'Reviewed-by' trailer to it:
265 +
266 ------------
267 $ git format-patch -1
268 0001-foo.patch
269 $ git interpret-trailers --trailer 'Cc: Alice <alice@example.com>' --trailer 'Reviewed-by: Bob <bob@example.com>' 0001-foo.patch >0001-bar.patch
270 ------------
271
272 * Configure a 'sign' trailer with a command to automatically add a
273 'Signed-off-by: ' with the author information only if there is no
274 'Signed-off-by: ' already, and show how it works:
275 +
276 ------------
277 $ git config trailer.sign.key "Signed-off-by: "
278 $ git config trailer.sign.ifmissing add
279 $ git config trailer.sign.ifexists doNothing
280 $ git config trailer.sign.command 'echo "$(git config user.name) <$(git config user.email)>"'
281 $ git interpret-trailers <<EOF
282 > EOF
283
284 Signed-off-by: Bob <bob@example.com>
285 $ git interpret-trailers <<EOF
286 > Signed-off-by: Alice <alice@example.com>
287 > EOF
288
289 Signed-off-by: Alice <alice@example.com>
290 ------------
291
292 * Configure a 'fix' trailer with a key that contains a '#' and no
293 space after this character, and show how it works:
294 +
295 ------------
296 $ git config trailer.separators ":#"
297 $ git config trailer.fix.key "Fix #"
298 $ echo "subject" | git interpret-trailers --trailer fix=42
299 subject
300
301 Fix #42
302 ------------
303
304 * Configure a 'see' trailer with a command to show the subject of a
305 commit that is related, and show how it works:
306 +
307 ------------
308 $ git config trailer.see.key "See-also: "
309 $ git config trailer.see.ifExists "replace"
310 $ git config trailer.see.ifMissing "doNothing"
311 $ git config trailer.see.command "git log -1 --oneline --format=\"%h (%s)\" --abbrev-commit --abbrev=14 \$ARG"
312 $ git interpret-trailers <<EOF
313 > subject
314 >
315 > message
316 >
317 > see: HEAD~2
318 > EOF
319 subject
320
321 message
322
323 See-also: fe3187489d69c4 (subject of related commit)
324 ------------
325
326 * Configure a commit template with some trailers with empty values
327 (using sed to show and keep the trailing spaces at the end of the
328 trailers), then configure a commit-msg hook that uses
329 'git interpret-trailers' to remove trailers with empty values and
330 to add a 'git-version' trailer:
331 +
332 ------------
333 $ sed -e 's/ Z$/ /' >commit_template.txt <<EOF
334 > ***subject***
335 >
336 > ***message***
337 >
338 > Fixes: Z
339 > Cc: Z
340 > Reviewed-by: Z
341 > Signed-off-by: Z
342 > EOF
343 $ git config commit.template commit_template.txt
344 $ cat >.git/hooks/commit-msg <<EOF
345 > #!/bin/sh
346 > git interpret-trailers --trim-empty --trailer "git-version: \$(git describe)" "\$1" > "\$1.new"
347 > mv "\$1.new" "\$1"
348 > EOF
349 $ chmod +x .git/hooks/commit-msg
350 ------------
351
352 SEE ALSO
353 --------
354 linkgit:git-commit[1], linkgit:git-format-patch[1], linkgit:git-config[1]
355
356 GIT
357 ---
358 Part of the linkgit:git[1] suite