1git-interpret-trailers(1) 2========================= 3 4NAME 5---- 6git-interpret-trailers - help add structured information into commit messages 7 8SYNOPSIS 9-------- 10[verse] 11'git interpret-trailers' [--in-place] [--trim-empty] [(--trailer <token>[(=|:)<value>])...] [<file>...] 12 13DESCRIPTION 14----------- 15Help adding 'trailers' lines, that look similar to RFC 822 e-mail 16headers, at the end of the otherwise free-form part of a commit 17message. 18 19This command reads some patches or commit messages from either the 20<file> arguments or the standard input if no <file> is specified. Then 21this command applies the arguments passed using the `--trailer` 22option, if any, to the commit message part of each input file. The 23result is emitted on the standard output. 24 25Some configuration variables control the way the `--trailer` arguments 26are applied to each commit message and the way any existing trailer in 27the commit message is changed. They also make it possible to 28automatically add some trailers. 29 30By default, a '<token>=<value>' or '<token>:<value>' argument given 31using `--trailer` will be appended after the existing trailers only if 32the last trailer has a different (<token>, <value>) pair (or if there 33is no existing trailer). The <token> and <value> parts will be trimmed 34to remove starting and trailing whitespace, and the resulting trimmed 35<token> and <value> will appear in the message like this: 36 37------------------------------------------------ 38token: value 39------------------------------------------------ 40 41This means that the trimmed <token> and <value> will be separated by 42`': '` (one colon followed by one space). 43 44By default the new trailer will appear at the end of all the existing 45trailers. If there is no existing trailer, the new trailer will appear 46after the commit message part of the output, and, if there is no line 47with only spaces at the end of the commit message part, one blank line 48will be added before the new trailer. 49 50Existing trailers are extracted from the input message by looking for 51a group of one or more lines that (i) are all trailers, or (ii) contains at 52least one Git-generated or user-configured trailer and consists of at 53least 25% trailers. 54The group must be preceded by one or more empty (or whitespace-only) lines. 55The group must either be at the end of the message or be the last 56non-whitespace lines before a line that starts with '---'. Such three 57minus signs start the patch part of the message. 58 59When reading trailers, there can be whitespaces after the 60token, the separator and the value. There can also be whitespaces 61inside the token and the value. The value may be split over multiple lines with 62each subsequent line starting with whitespace, like the "folding" in RFC 822. 63 64Note that 'trailers' do not follow and are not intended to follow many 65rules for RFC 822 headers. For example they do not follow 66the encoding rules and probably many other rules. 67 68OPTIONS 69------- 70--in-place:: 71 Edit the files in place. 72 73--trim-empty:: 74 If the <value> part of any trailer contains only whitespace, 75 the whole trailer will be removed from the resulting message. 76 This applies to existing trailers as well as new trailers. 77 78--trailer <token>[(=|:)<value>]:: 79 Specify a (<token>, <value>) pair that should be applied as a 80 trailer to the input messages. See the description of this 81 command. 82 83--only-trailers:: 84 Output only the trailers, not any other parts of the input. 85 86CONFIGURATION VARIABLES 87----------------------- 88 89trailer.separators:: 90 This option tells which characters are recognized as trailer 91 separators. By default only ':' is recognized as a trailer 92 separator, except that '=' is always accepted on the command 93 line for compatibility with other git commands. 94+ 95The first character given by this option will be the default character 96used when another separator is not specified in the config for this 97trailer. 98+ 99For example, if the value for this option is "%=$", then only lines 100using the format '<token><sep><value>' with <sep> containing '%', '=' 101or '$' and then spaces will be considered trailers. And '%' will be 102the default separator used, so by default trailers will appear like: 103'<token>% <value>' (one percent sign and one space will appear between 104the token and the value). 105 106trailer.where:: 107 This option tells where a new trailer will be added. 108+ 109This can be `end`, which is the default, `start`, `after` or `before`. 110+ 111If it is `end`, then each new trailer will appear at the end of the 112existing trailers. 113+ 114If it is `start`, then each new trailer will appear at the start, 115instead of the end, of the existing trailers. 116+ 117If it is `after`, then each new trailer will appear just after the 118last trailer with the same <token>. 119+ 120If it is `before`, then each new trailer will appear just before the 121first trailer with the same <token>. 122 123trailer.ifexists:: 124 This option makes it possible to choose what action will be 125 performed when there is already at least one trailer with the 126 same <token> in the message. 127+ 128The valid values for this option are: `addIfDifferentNeighbor` (this 129is the default), `addIfDifferent`, `add`, `replace` or `doNothing`. 130+ 131With `addIfDifferentNeighbor`, a new trailer will be added only if no 132trailer with the same (<token>, <value>) pair is above or below the line 133where the new trailer will be added. 134+ 135With `addIfDifferent`, a new trailer will be added only if no trailer 136with the same (<token>, <value>) pair is already in the message. 137+ 138With `add`, a new trailer will be added, even if some trailers with 139the same (<token>, <value>) pair are already in the message. 140+ 141With `replace`, an existing trailer with the same <token> will be 142deleted and the new trailer will be added. The deleted trailer will be 143the closest one (with the same <token>) to the place where the new one 144will be added. 145+ 146With `doNothing`, nothing will be done; that is no new trailer will be 147added if there is already one with the same <token> in the message. 148 149trailer.ifmissing:: 150 This option makes it possible to choose what action will be 151 performed when there is not yet any trailer with the same 152 <token> in the message. 153+ 154The valid values for this option are: `add` (this is the default) and 155`doNothing`. 156+ 157With `add`, a new trailer will be added. 158+ 159With `doNothing`, nothing will be done. 160 161trailer.<token>.key:: 162 This `key` will be used instead of <token> in the trailer. At 163 the end of this key, a separator can appear and then some 164 space characters. By default the only valid separator is ':', 165 but this can be changed using the `trailer.separators` config 166 variable. 167+ 168If there is a separator, then the key will be used instead of both the 169<token> and the default separator when adding the trailer. 170 171trailer.<token>.where:: 172 This option takes the same values as the 'trailer.where' 173 configuration variable and it overrides what is specified by 174 that option for trailers with the specified <token>. 175 176trailer.<token>.ifexist:: 177 This option takes the same values as the 'trailer.ifexist' 178 configuration variable and it overrides what is specified by 179 that option for trailers with the specified <token>. 180 181trailer.<token>.ifmissing:: 182 This option takes the same values as the 'trailer.ifmissing' 183 configuration variable and it overrides what is specified by 184 that option for trailers with the specified <token>. 185 186trailer.<token>.command:: 187 This option can be used to specify a shell command that will 188 be called to automatically add or modify a trailer with the 189 specified <token>. 190+ 191When this option is specified, the behavior is as if a special 192'<token>=<value>' argument were added at the beginning of the command 193line, where <value> is taken to be the standard output of the 194specified command with any leading and trailing whitespace trimmed 195off. 196+ 197If the command contains the `$ARG` string, this string will be 198replaced with the <value> part of an existing trailer with the same 199<token>, if any, before the command is launched. 200+ 201If some '<token>=<value>' arguments are also passed on the command 202line, when a 'trailer.<token>.command' is configured, the command will 203also be executed for each of these arguments. And the <value> part of 204these arguments, if any, will be used to replace the `$ARG` string in 205the command. 206 207EXAMPLES 208-------- 209 210* Configure a 'sign' trailer with a 'Signed-off-by' key, and then 211 add two of these trailers to a message: 212+ 213------------ 214$ git config trailer.sign.key "Signed-off-by" 215$ cat msg.txt 216subject 217 218message 219$ cat msg.txt | git interpret-trailers --trailer 'sign: Alice <alice@example.com>' --trailer 'sign: Bob <bob@example.com>' 220subject 221 222message 223 224Signed-off-by: Alice <alice@example.com> 225Signed-off-by: Bob <bob@example.com> 226------------ 227 228* Use the `--in-place` option to edit a message file in place: 229+ 230------------ 231$ cat msg.txt 232subject 233 234message 235 236Signed-off-by: Bob <bob@example.com> 237$ git interpret-trailers --trailer 'Acked-by: Alice <alice@example.com>' --in-place msg.txt 238$ cat msg.txt 239subject 240 241message 242 243Signed-off-by: Bob <bob@example.com> 244Acked-by: Alice <alice@example.com> 245------------ 246 247* Extract the last commit as a patch, and add a 'Cc' and a 248 'Reviewed-by' trailer to it: 249+ 250------------ 251$ git format-patch -1 2520001-foo.patch 253$ git interpret-trailers --trailer 'Cc: Alice <alice@example.com>' --trailer 'Reviewed-by: Bob <bob@example.com>' 0001-foo.patch >0001-bar.patch 254------------ 255 256* Configure a 'sign' trailer with a command to automatically add a 257 'Signed-off-by: ' with the author information only if there is no 258 'Signed-off-by: ' already, and show how it works: 259+ 260------------ 261$ git config trailer.sign.key "Signed-off-by: " 262$ git config trailer.sign.ifmissing add 263$ git config trailer.sign.ifexists doNothing 264$ git config trailer.sign.command 'echo "$(git config user.name) <$(git config user.email)>"' 265$ git interpret-trailers <<EOF 266> EOF 267 268Signed-off-by: Bob <bob@example.com> 269$ git interpret-trailers <<EOF 270> Signed-off-by: Alice <alice@example.com> 271> EOF 272 273Signed-off-by: Alice <alice@example.com> 274------------ 275 276* Configure a 'fix' trailer with a key that contains a '#' and no 277 space after this character, and show how it works: 278+ 279------------ 280$ git config trailer.separators ":#" 281$ git config trailer.fix.key "Fix #" 282$ echo "subject" | git interpret-trailers --trailer fix=42 283subject 284 285Fix #42 286------------ 287 288* Configure a 'see' trailer with a command to show the subject of a 289 commit that is related, and show how it works: 290+ 291------------ 292$ git config trailer.see.key "See-also: " 293$ git config trailer.see.ifExists "replace" 294$ git config trailer.see.ifMissing "doNothing" 295$ git config trailer.see.command "git log -1 --oneline --format=\"%h (%s)\" --abbrev-commit --abbrev=14 \$ARG" 296$ git interpret-trailers <<EOF 297> subject 298> 299> message 300> 301> see: HEAD~2 302> EOF 303subject 304 305message 306 307See-also: fe3187489d69c4 (subject of related commit) 308------------ 309 310* Configure a commit template with some trailers with empty values 311 (using sed to show and keep the trailing spaces at the end of the 312 trailers), then configure a commit-msg hook that uses 313 'git interpret-trailers' to remove trailers with empty values and 314 to add a 'git-version' trailer: 315+ 316------------ 317$ sed -e 's/ Z$/ /' >commit_template.txt <<EOF 318> ***subject*** 319> 320> ***message*** 321> 322> Fixes: Z 323> Cc: Z 324> Reviewed-by: Z 325> Signed-off-by: Z 326> EOF 327$ git config commit.template commit_template.txt 328$ cat >.git/hooks/commit-msg <<EOF 329> #!/bin/sh 330> git interpret-trailers --trim-empty --trailer "git-version: \$(git describe)" "\$1" > "\$1.new" 331> mv "\$1.new" "\$1" 332> EOF 333$ chmod +x .git/hooks/commit-msg 334------------ 335 336SEE ALSO 337-------- 338linkgit:git-commit[1], linkgit:git-format-patch[1], linkgit:git-config[1] 339 340GIT 341--- 342Part of the linkgit:git[1] suite