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--where <placement>:: 84--no-where:: 85 Specify where all new trailers will be added. A setting 86 provided with '--where' overrides all configuration variables 87 and applies to all '--trailer' options until the next occurrence of 88 '--where' or '--no-where'. 89 90--if-exists <action>:: 91--no-if-exists:: 92 Specify what action will be performed when there is already at 93 least one trailer with the same <token> in the message. A setting 94 provided with '--if-exists' overrides all configuration variables 95 and applies to all '--trailer' options until the next occurrence of 96 '--if-exists' or '--no-if-exists'. 97 98--if-missing <action>:: 99--no-if-missing:: 100 Specify what action will be performed when there is no other 101 trailer with the same <token> in the message. A setting 102 provided with '--if-missing' overrides all configuration variables 103 and applies to all '--trailer' options until the next occurrence of 104 '--if-missing' or '--no-if-missing'. 105 106CONFIGURATION VARIABLES 107----------------------- 108 109trailer.separators:: 110 This option tells which characters are recognized as trailer 111 separators. By default only ':' is recognized as a trailer 112 separator, except that '=' is always accepted on the command 113 line for compatibility with other git commands. 114+ 115The first character given by this option will be the default character 116used when another separator is not specified in the config for this 117trailer. 118+ 119For example, if the value for this option is "%=$", then only lines 120using the format '<token><sep><value>' with <sep> containing '%', '=' 121or '$' and then spaces will be considered trailers. And '%' will be 122the default separator used, so by default trailers will appear like: 123'<token>% <value>' (one percent sign and one space will appear between 124the token and the value). 125 126trailer.where:: 127 This option tells where a new trailer will be added. 128+ 129This can be `end`, which is the default, `start`, `after` or `before`. 130+ 131If it is `end`, then each new trailer will appear at the end of the 132existing trailers. 133+ 134If it is `start`, then each new trailer will appear at the start, 135instead of the end, of the existing trailers. 136+ 137If it is `after`, then each new trailer will appear just after the 138last trailer with the same <token>. 139+ 140If it is `before`, then each new trailer will appear just before the 141first trailer with the same <token>. 142 143trailer.ifexists:: 144 This option makes it possible to choose what action will be 145 performed when there is already at least one trailer with the 146 same <token> in the message. 147+ 148The valid values for this option are: `addIfDifferentNeighbor` (this 149is the default), `addIfDifferent`, `add`, `replace` or `doNothing`. 150+ 151With `addIfDifferentNeighbor`, a new trailer will be added only if no 152trailer with the same (<token>, <value>) pair is above or below the line 153where the new trailer will be added. 154+ 155With `addIfDifferent`, a new trailer will be added only if no trailer 156with the same (<token>, <value>) pair is already in the message. 157+ 158With `add`, a new trailer will be added, even if some trailers with 159the same (<token>, <value>) pair are already in the message. 160+ 161With `replace`, an existing trailer with the same <token> will be 162deleted and the new trailer will be added. The deleted trailer will be 163the closest one (with the same <token>) to the place where the new one 164will be added. 165+ 166With `doNothing`, nothing will be done; that is no new trailer will be 167added if there is already one with the same <token> in the message. 168 169trailer.ifmissing:: 170 This option makes it possible to choose what action will be 171 performed when there is not yet any trailer with the same 172 <token> in the message. 173+ 174The valid values for this option are: `add` (this is the default) and 175`doNothing`. 176+ 177With `add`, a new trailer will be added. 178+ 179With `doNothing`, nothing will be done. 180 181trailer.<token>.key:: 182 This `key` will be used instead of <token> in the trailer. At 183 the end of this key, a separator can appear and then some 184 space characters. By default the only valid separator is ':', 185 but this can be changed using the `trailer.separators` config 186 variable. 187+ 188If there is a separator, then the key will be used instead of both the 189<token> and the default separator when adding the trailer. 190 191trailer.<token>.where:: 192 This option takes the same values as the 'trailer.where' 193 configuration variable and it overrides what is specified by 194 that option for trailers with the specified <token>. 195 196trailer.<token>.ifexist:: 197 This option takes the same values as the 'trailer.ifexist' 198 configuration variable and it overrides what is specified by 199 that option for trailers with the specified <token>. 200 201trailer.<token>.ifmissing:: 202 This option takes the same values as the 'trailer.ifmissing' 203 configuration variable and it overrides what is specified by 204 that option for trailers with the specified <token>. 205 206trailer.<token>.command:: 207 This option can be used to specify a shell command that will 208 be called to automatically add or modify a trailer with the 209 specified <token>. 210+ 211When this option is specified, the behavior is as if a special 212'<token>=<value>' argument were added at the beginning of the command 213line, where <value> is taken to be the standard output of the 214specified command with any leading and trailing whitespace trimmed 215off. 216+ 217If the command contains the `$ARG` string, this string will be 218replaced with the <value> part of an existing trailer with the same 219<token>, if any, before the command is launched. 220+ 221If some '<token>=<value>' arguments are also passed on the command 222line, when a 'trailer.<token>.command' is configured, the command will 223also be executed for each of these arguments. And the <value> part of 224these arguments, if any, will be used to replace the `$ARG` string in 225the command. 226 227EXAMPLES 228-------- 229 230* Configure a 'sign' trailer with a 'Signed-off-by' key, and then 231 add two of these trailers to a message: 232+ 233------------ 234$ git config trailer.sign.key "Signed-off-by" 235$ cat msg.txt 236subject 237 238message 239$ cat msg.txt | git interpret-trailers --trailer 'sign: Alice <alice@example.com>' --trailer 'sign: Bob <bob@example.com>' 240subject 241 242message 243 244Signed-off-by: Alice <alice@example.com> 245Signed-off-by: Bob <bob@example.com> 246------------ 247 248* Use the `--in-place` option to edit a message file in place: 249+ 250------------ 251$ cat msg.txt 252subject 253 254message 255 256Signed-off-by: Bob <bob@example.com> 257$ git interpret-trailers --trailer 'Acked-by: Alice <alice@example.com>' --in-place msg.txt 258$ cat msg.txt 259subject 260 261message 262 263Signed-off-by: Bob <bob@example.com> 264Acked-by: Alice <alice@example.com> 265------------ 266 267* Extract the last commit as a patch, and add a 'Cc' and a 268 'Reviewed-by' trailer to it: 269+ 270------------ 271$ git format-patch -1 2720001-foo.patch 273$ git interpret-trailers --trailer 'Cc: Alice <alice@example.com>' --trailer 'Reviewed-by: Bob <bob@example.com>' 0001-foo.patch >0001-bar.patch 274------------ 275 276* Configure a 'sign' trailer with a command to automatically add a 277 'Signed-off-by: ' with the author information only if there is no 278 'Signed-off-by: ' already, and show how it works: 279+ 280------------ 281$ git config trailer.sign.key "Signed-off-by: " 282$ git config trailer.sign.ifmissing add 283$ git config trailer.sign.ifexists doNothing 284$ git config trailer.sign.command 'echo "$(git config user.name) <$(git config user.email)>"' 285$ git interpret-trailers <<EOF 286> EOF 287 288Signed-off-by: Bob <bob@example.com> 289$ git interpret-trailers <<EOF 290> Signed-off-by: Alice <alice@example.com> 291> EOF 292 293Signed-off-by: Alice <alice@example.com> 294------------ 295 296* Configure a 'fix' trailer with a key that contains a '#' and no 297 space after this character, and show how it works: 298+ 299------------ 300$ git config trailer.separators ":#" 301$ git config trailer.fix.key "Fix #" 302$ echo "subject" | git interpret-trailers --trailer fix=42 303subject 304 305Fix #42 306------------ 307 308* Configure a 'see' trailer with a command to show the subject of a 309 commit that is related, and show how it works: 310+ 311------------ 312$ git config trailer.see.key "See-also: " 313$ git config trailer.see.ifExists "replace" 314$ git config trailer.see.ifMissing "doNothing" 315$ git config trailer.see.command "git log -1 --oneline --format=\"%h (%s)\" --abbrev-commit --abbrev=14 \$ARG" 316$ git interpret-trailers <<EOF 317> subject 318> 319> message 320> 321> see: HEAD~2 322> EOF 323subject 324 325message 326 327See-also: fe3187489d69c4 (subject of related commit) 328------------ 329 330* Configure a commit template with some trailers with empty values 331 (using sed to show and keep the trailing spaces at the end of the 332 trailers), then configure a commit-msg hook that uses 333 'git interpret-trailers' to remove trailers with empty values and 334 to add a 'git-version' trailer: 335+ 336------------ 337$ sed -e 's/ Z$/ /' >commit_template.txt <<EOF 338> ***subject*** 339> 340> ***message*** 341> 342> Fixes: Z 343> Cc: Z 344> Reviewed-by: Z 345> Signed-off-by: Z 346> EOF 347$ git config commit.template commit_template.txt 348$ cat >.git/hooks/commit-msg <<EOF 349> #!/bin/sh 350> git interpret-trailers --trim-empty --trailer "git-version: \$(git describe)" "\$1" > "\$1.new" 351> mv "\$1.new" "\$1" 352> EOF 353$ chmod +x .git/hooks/commit-msg 354------------ 355 356SEE ALSO 357-------- 358linkgit:git-commit[1], linkgit:git-format-patch[1], linkgit:git-config[1] 359 360GIT 361--- 362Part of the linkgit:git[1] suite