1 git-interpret-trailers(1)
2 =========================
6 git-interpret-trailers - help add structured information into commit messages
11 'git interpret-trailers' [--in-place] [--trim-empty] [(--trailer <token>[(=|:)<value>])...] [<file>...]
15 Help adding 'trailers' lines, that look similar to RFC 822 e-mail
16 headers, at the end of the otherwise free-form part of a commit
19 This command reads some patches or commit messages from either the
20 <file> arguments or the standard input if no <file> is specified. Then
21 this command applies the arguments passed using the `--trailer`
22 option, if any, to the commit message part of each input file. The
23 result is emitted on the standard output.
25 Some configuration variables control the way the `--trailer` arguments
26 are applied to each commit message and the way any existing trailer in
27 the commit message is changed. They also make it possible to
28 automatically add some trailers.
30 By default, a '<token>=<value>' or '<token>:<value>' argument given
31 using `--trailer` will be appended after the existing trailers only if
32 the last trailer has a different (<token>, <value>) pair (or if there
33 is no existing trailer). The <token> and <value> parts will be trimmed
34 to remove starting and trailing whitespace, and the resulting trimmed
35 <token> and <value> will appear in the message like this:
37 ------------------------------------------------
39 ------------------------------------------------
41 This means that the trimmed <token> and <value> will be separated by
42 `': '` (one colon followed by one space).
44 By default the new trailer will appear at the end of all the existing
45 trailers. If there is no existing trailer, the new trailer will appear
46 after the commit message part of the output, and, if there is no line
47 with only spaces at the end of the commit message part, one blank line
48 will be added before the new trailer.
50 Existing trailers are extracted from the input message by looking for
51 a group of one or more lines that (i) are all trailers, or (ii) contains at
52 least one Git-generated trailer and consists of at least 25% trailers.
53 The group must be preceded by one or more empty (or whitespace-only) lines.
54 The group must either be at the end of the message or be the last
55 non-whitespace lines before a line that starts with '---'. Such three
56 minus signs start the patch part of the message.
58 When reading trailers, there can be whitespaces after the
59 token, the separator and the value. There can also be whitespaces
60 inside the token and the value. The value may be split over multiple lines with
61 each subsequent line starting with whitespace, like the "folding" in RFC 822.
63 Note that 'trailers' do not follow and are not intended to follow many
64 rules for RFC 822 headers. For example they do not follow
65 the encoding rules and probably many other rules.
70 Edit the files in place.
73 If the <value> part of any trailer contains only whitespace,
74 the whole trailer will be removed from the resulting message.
75 This applies to existing trailers as well as new trailers.
77 --trailer <token>[(=|:)<value>]::
78 Specify a (<token>, <value>) pair that should be applied as a
79 trailer to the input messages. See the description of this
82 CONFIGURATION VARIABLES
83 -----------------------
86 This option tells which characters are recognized as trailer
87 separators. By default only ':' is recognized as a trailer
88 separator, except that '=' is always accepted on the command
89 line for compatibility with other git commands.
91 The first character given by this option will be the default character
92 used when another separator is not specified in the config for this
95 For example, if the value for this option is "%=$", then only lines
96 using the format '<token><sep><value>' with <sep> containing '%', '='
97 or '$' and then spaces will be considered trailers. And '%' will be
98 the default separator used, so by default trailers will appear like:
99 '<token>% <value>' (one percent sign and one space will appear between
100 the token and the value).
103 This option tells where a new trailer will be added.
105 This can be `end`, which is the default, `start`, `after` or `before`.
107 If it is `end`, then each new trailer will appear at the end of the
110 If it is `start`, then each new trailer will appear at the start,
111 instead of the end, of the existing trailers.
113 If it is `after`, then each new trailer will appear just after the
114 last trailer with the same <token>.
116 If it is `before`, then each new trailer will appear just before the
117 first trailer with the same <token>.
120 This option makes it possible to choose what action will be
121 performed when there is already at least one trailer with the
122 same <token> in the message.
124 The valid values for this option are: `addIfDifferentNeighbor` (this
125 is the default), `addIfDifferent`, `add`, `overwrite` or `doNothing`.
127 With `addIfDifferentNeighbor`, a new trailer will be added only if no
128 trailer with the same (<token>, <value>) pair is above or below the line
129 where the new trailer will be added.
131 With `addIfDifferent`, a new trailer will be added only if no trailer
132 with the same (<token>, <value>) pair is already in the message.
134 With `add`, a new trailer will be added, even if some trailers with
135 the same (<token>, <value>) pair are already in the message.
137 With `replace`, an existing trailer with the same <token> will be
138 deleted and the new trailer will be added. The deleted trailer will be
139 the closest one (with the same <token>) to the place where the new one
142 With `doNothing`, nothing will be done; that is no new trailer will be
143 added if there is already one with the same <token> in the message.
146 This option makes it possible to choose what action will be
147 performed when there is not yet any trailer with the same
148 <token> in the message.
150 The valid values for this option are: `add` (this is the default) and
153 With `add`, a new trailer will be added.
155 With `doNothing`, nothing will be done.
157 trailer.<token>.key::
158 This `key` will be used instead of <token> in the trailer. At
159 the end of this key, a separator can appear and then some
160 space characters. By default the only valid separator is ':',
161 but this can be changed using the `trailer.separators` config
164 If there is a separator, then the key will be used instead of both the
165 <token> and the default separator when adding the trailer.
167 trailer.<token>.where::
168 This option takes the same values as the 'trailer.where'
169 configuration variable and it overrides what is specified by
170 that option for trailers with the specified <token>.
172 trailer.<token>.ifexist::
173 This option takes the same values as the 'trailer.ifexist'
174 configuration variable and it overrides what is specified by
175 that option for trailers with the specified <token>.
177 trailer.<token>.ifmissing::
178 This option takes the same values as the 'trailer.ifmissing'
179 configuration variable and it overrides what is specified by
180 that option for trailers with the specified <token>.
182 trailer.<token>.command::
183 This option can be used to specify a shell command that will
184 be called to automatically add or modify a trailer with the
187 When this option is specified, the behavior is as if a special
188 '<token>=<value>' argument were added at the beginning of the command
189 line, where <value> is taken to be the standard output of the
190 specified command with any leading and trailing whitespace trimmed
193 If the command contains the `$ARG` string, this string will be
194 replaced with the <value> part of an existing trailer with the same
195 <token>, if any, before the command is launched.
197 If some '<token>=<value>' arguments are also passed on the command
198 line, when a 'trailer.<token>.command' is configured, the command will
199 also be executed for each of these arguments. And the <value> part of
200 these arguments, if any, will be used to replace the `$ARG` string in
206 * Configure a 'sign' trailer with a 'Signed-off-by' key, and then
207 add two of these trailers to a message:
210 $ git config trailer.sign.key "Signed-off-by"
215 $ cat msg.txt | git interpret-trailers --trailer 'sign: Alice <alice@example.com>' --trailer 'sign: Bob <bob@example.com>'
220 Signed-off-by: Alice <alice@example.com>
221 Signed-off-by: Bob <bob@example.com>
224 * Use the `--in-place` option to edit a message file in place:
232 Signed-off-by: Bob <bob@example.com>
233 $ git interpret-trailers --trailer 'Acked-by: Alice <alice@example.com>' --in-place msg.txt
239 Signed-off-by: Bob <bob@example.com>
240 Acked-by: Alice <alice@example.com>
243 * Extract the last commit as a patch, and add a 'Cc' and a
244 'Reviewed-by' trailer to it:
247 $ git format-patch -1
249 $ git interpret-trailers --trailer 'Cc: Alice <alice@example.com>' --trailer 'Reviewed-by: Bob <bob@example.com>' 0001-foo.patch >0001-bar.patch
252 * Configure a 'sign' trailer with a command to automatically add a
253 'Signed-off-by: ' with the author information only if there is no
254 'Signed-off-by: ' already, and show how it works:
257 $ git config trailer.sign.key "Signed-off-by: "
258 $ git config trailer.sign.ifmissing add
259 $ git config trailer.sign.ifexists doNothing
260 $ git config trailer.sign.command 'echo "$(git config user.name) <$(git config user.email)>"'
261 $ git interpret-trailers <<EOF
264 Signed-off-by: Bob <bob@example.com>
265 $ git interpret-trailers <<EOF
266 > Signed-off-by: Alice <alice@example.com>
269 Signed-off-by: Alice <alice@example.com>
272 * Configure a 'fix' trailer with a key that contains a '#' and no
273 space after this character, and show how it works:
276 $ git config trailer.separators ":#"
277 $ git config trailer.fix.key "Fix #"
278 $ echo "subject" | git interpret-trailers --trailer fix=42
284 * Configure a 'see' trailer with a command to show the subject of a
285 commit that is related, and show how it works:
288 $ git config trailer.see.key "See-also: "
289 $ git config trailer.see.ifExists "replace"
290 $ git config trailer.see.ifMissing "doNothing"
291 $ git config trailer.see.command "git log -1 --oneline --format=\"%h (%s)\" --abbrev-commit --abbrev=14 \$ARG"
292 $ git interpret-trailers <<EOF
303 See-also: fe3187489d69c4 (subject of related commit)
306 * Configure a commit template with some trailers with empty values
307 (using sed to show and keep the trailing spaces at the end of the
308 trailers), then configure a commit-msg hook that uses
309 'git interpret-trailers' to remove trailers with empty values and
310 to add a 'git-version' trailer:
313 $ sed -e 's/ Z$/ /' >commit_template.txt <<EOF
323 $ git config commit.template commit_template.txt
324 $ cat >.git/hooks/commit-msg <<EOF
326 > git interpret-trailers --trim-empty --trailer "git-version: \$(git describe)" "\$1" > "\$1.new"
329 $ chmod +x .git/hooks/commit-msg
334 linkgit:git-commit[1], linkgit:git-format-patch[1], linkgit:git-config[1]
338 Part of the linkgit:git[1] suite