1git-interpret-trailers(1) 2========================= 3 4NAME 5---- 6git-interpret-trailers - add or parse structured information in commit messages 7 8SYNOPSIS 9-------- 10[verse] 11'git interpret-trailers' [<options>] [(--trailer <token>[(=|:)<value>])...] [<file>...] 12'git interpret-trailers' [<options>] [--parse] [<file>...] 13 14DESCRIPTION 15----------- 16Help parsing or adding 'trailers' lines, that look similar to RFC 822 e-mail 17headers, at the end of the otherwise free-form part of a commit 18message. 19 20This 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 24Otherwise, this command applies the arguments passed using the 25`--trailer` option, if any, to the commit message part of each input 26file. The result is emitted on the standard output. 27 28Some configuration variables control the way the `--trailer` arguments 29are applied to each commit message and the way any existing trailer in 30the commit message is changed. They also make it possible to 31automatically add some trailers. 32 33By default, a '<token>=<value>' or '<token>:<value>' argument given 34using `--trailer` will be appended after the existing trailers only if 35the last trailer has a different (<token>, <value>) pair (or if there 36is no existing trailer). The <token> and <value> parts will be trimmed 37to remove starting and trailing whitespace, and the resulting trimmed 38<token> and <value> will appear in the message like this: 39 40------------------------------------------------ 41token: value 42------------------------------------------------ 43 44This means that the trimmed <token> and <value> will be separated by 45`': '` (one colon followed by one space). 46 47By default the new trailer will appear at the end of all the existing 48trailers. If there is no existing trailer, the new trailer will appear 49after the commit message part of the output, and, if there is no line 50with only spaces at the end of the commit message part, one blank line 51will be added before the new trailer. 52 53Existing trailers are extracted from the input message by looking for 54a group of one or more lines that (i) is all trailers, or (ii) contains at 55least one Git-generated or user-configured trailer and consists of at 56least 25% trailers. 57The group must be preceded by one or more empty (or whitespace-only) lines. 58The group must either be at the end of the message or be the last 59non-whitespace lines before a line that starts with '---' (followed by a 60space or the end of the line). Such three minus signs start the patch 61part of the message. 62 63When reading trailers, there can be whitespaces after the 64token, the separator and the value. There can also be whitespaces 65inside the token and the value. The value may be split over multiple lines with 66each subsequent line starting with whitespace, like the "folding" in RFC 822. 67 68Note that 'trailers' do not follow and are not intended to follow many 69rules for RFC 822 headers. For example they do not follow 70the encoding rules and probably many other rules. 71 72OPTIONS 73------- 74--in-place:: 75 Edit the files in place. 76 77--trim-empty:: 78 If the <value> part of any trailer contains only whitespace, 79 the whole trailer will be removed from the resulting message. 80 This applies to existing trailers as well as new trailers. 81 82--trailer <token>[(=|:)<value>]:: 83 Specify a (<token>, <value>) pair that should be applied as a 84 trailer to the input messages. See the description of this 85 command. 86 87--where <placement>:: 88--no-where:: 89 Specify where all new trailers will be added. A setting 90 provided with '--where' overrides all configuration variables 91 and applies to all '--trailer' options until the next occurrence of 92 '--where' or '--no-where'. 93 94--if-exists <action>:: 95--no-if-exists:: 96 Specify what action will be performed when there is already at 97 least one trailer with the same <token> in the message. A setting 98 provided with '--if-exists' overrides all configuration variables 99 and applies to all '--trailer' options until the next occurrence of 100 '--if-exists' or '--no-if-exists'. 101 102--if-missing <action>:: 103--no-if-missing:: 104 Specify what action will be performed when there is no other 105 trailer with the same <token> in the message. A setting 106 provided with '--if-missing' overrides all configuration variables 107 and applies to all '--trailer' options until the next occurrence of 108 '--if-missing' or '--no-if-missing'. 109 110--only-trailers:: 111 Output only the trailers, not any other parts of the input. 112 113--only-input:: 114 Output only trailers that exist in the input; do not add any 115 from the command-line or by following configured `trailer.*` 116 rules. 117 118--unfold:: 119 Remove any whitespace-continuation in trailers, so that each 120 trailer appears on a line by itself with its full content. 121 122--parse:: 123 A convenience alias for `--only-trailers --only-input 124 --unfold`. 125 126CONFIGURATION VARIABLES 127----------------------- 128 129trailer.separators:: 130 This option tells which characters are recognized as trailer 131 separators. By default only ':' is recognized as a trailer 132 separator, except that '=' is always accepted on the command 133 line for compatibility with other git commands. 134+ 135The first character given by this option will be the default character 136used when another separator is not specified in the config for this 137trailer. 138+ 139For example, if the value for this option is "%=$", then only lines 140using the format '<token><sep><value>' with <sep> containing '%', '=' 141or '$' and then spaces will be considered trailers. And '%' will be 142the default separator used, so by default trailers will appear like: 143'<token>% <value>' (one percent sign and one space will appear between 144the token and the value). 145 146trailer.where:: 147 This option tells where a new trailer will be added. 148+ 149This can be `end`, which is the default, `start`, `after` or `before`. 150+ 151If it is `end`, then each new trailer will appear at the end of the 152existing trailers. 153+ 154If it is `start`, then each new trailer will appear at the start, 155instead of the end, of the existing trailers. 156+ 157If it is `after`, then each new trailer will appear just after the 158last trailer with the same <token>. 159+ 160If it is `before`, then each new trailer will appear just before the 161first trailer with the same <token>. 162 163trailer.ifexists:: 164 This option makes it possible to choose what action will be 165 performed when there is already at least one trailer with the 166 same <token> in the message. 167+ 168The valid values for this option are: `addIfDifferentNeighbor` (this 169is the default), `addIfDifferent`, `add`, `replace` or `doNothing`. 170+ 171With `addIfDifferentNeighbor`, a new trailer will be added only if no 172trailer with the same (<token>, <value>) pair is above or below the line 173where the new trailer will be added. 174+ 175With `addIfDifferent`, a new trailer will be added only if no trailer 176with the same (<token>, <value>) pair is already in the message. 177+ 178With `add`, a new trailer will be added, even if some trailers with 179the same (<token>, <value>) pair are already in the message. 180+ 181With `replace`, an existing trailer with the same <token> will be 182deleted and the new trailer will be added. The deleted trailer will be 183the closest one (with the same <token>) to the place where the new one 184will be added. 185+ 186With `doNothing`, nothing will be done; that is no new trailer will be 187added if there is already one with the same <token> in the message. 188 189trailer.ifmissing:: 190 This option makes it possible to choose what action will be 191 performed when there is not yet any trailer with the same 192 <token> in the message. 193+ 194The valid values for this option are: `add` (this is the default) and 195`doNothing`. 196+ 197With `add`, a new trailer will be added. 198+ 199With `doNothing`, nothing will be done. 200 201trailer.<token>.key:: 202 This `key` will be used instead of <token> in the trailer. At 203 the end of this key, a separator can appear and then some 204 space characters. By default the only valid separator is ':', 205 but this can be changed using the `trailer.separators` config 206 variable. 207+ 208If there is a separator, then the key will be used instead of both the 209<token> and the default separator when adding the trailer. 210 211trailer.<token>.where:: 212 This option takes the same values as the 'trailer.where' 213 configuration variable and it overrides what is specified by 214 that option for trailers with the specified <token>. 215 216trailer.<token>.ifexists:: 217 This option takes the same values as the 'trailer.ifexists' 218 configuration variable and it overrides what is specified by 219 that option for trailers with the specified <token>. 220 221trailer.<token>.ifmissing:: 222 This option takes the same values as the 'trailer.ifmissing' 223 configuration variable and it overrides what is specified by 224 that option for trailers with the specified <token>. 225 226trailer.<token>.command:: 227 This option can be used to specify a shell command that will 228 be called to automatically add or modify a trailer with the 229 specified <token>. 230+ 231When this option is specified, the behavior is as if a special 232'<token>=<value>' argument were added at the beginning of the command 233line, where <value> is taken to be the standard output of the 234specified command with any leading and trailing whitespace trimmed 235off. 236+ 237If the command contains the `$ARG` string, this string will be 238replaced with the <value> part of an existing trailer with the same 239<token>, if any, before the command is launched. 240+ 241If some '<token>=<value>' arguments are also passed on the command 242line, when a 'trailer.<token>.command' is configured, the command will 243also be executed for each of these arguments. And the <value> part of 244these arguments, if any, will be used to replace the `$ARG` string in 245the command. 246 247EXAMPLES 248-------- 249 250* Configure a 'sign' trailer with a 'Signed-off-by' key, and then 251 add two of these trailers to a message: 252+ 253------------ 254$ git config trailer.sign.key "Signed-off-by" 255$ cat msg.txt 256subject 257 258message 259$ cat msg.txt | git interpret-trailers --trailer 'sign: Alice <alice@example.com>' --trailer 'sign: Bob <bob@example.com>' 260subject 261 262message 263 264Signed-off-by: Alice <alice@example.com> 265Signed-off-by: Bob <bob@example.com> 266------------ 267 268* Use the `--in-place` option to edit a message file in place: 269+ 270------------ 271$ cat msg.txt 272subject 273 274message 275 276Signed-off-by: Bob <bob@example.com> 277$ git interpret-trailers --trailer 'Acked-by: Alice <alice@example.com>' --in-place msg.txt 278$ cat msg.txt 279subject 280 281message 282 283Signed-off-by: Bob <bob@example.com> 284Acked-by: Alice <alice@example.com> 285------------ 286 287* Extract the last commit as a patch, and add a 'Cc' and a 288 'Reviewed-by' trailer to it: 289+ 290------------ 291$ git format-patch -1 2920001-foo.patch 293$ git interpret-trailers --trailer 'Cc: Alice <alice@example.com>' --trailer 'Reviewed-by: Bob <bob@example.com>' 0001-foo.patch >0001-bar.patch 294------------ 295 296* Configure a 'sign' trailer with a command to automatically add a 297 'Signed-off-by: ' with the author information only if there is no 298 'Signed-off-by: ' already, and show how it works: 299+ 300------------ 301$ git config trailer.sign.key "Signed-off-by: " 302$ git config trailer.sign.ifmissing add 303$ git config trailer.sign.ifexists doNothing 304$ git config trailer.sign.command 'echo "$(git config user.name) <$(git config user.email)>"' 305$ git interpret-trailers <<EOF 306> EOF 307 308Signed-off-by: Bob <bob@example.com> 309$ git interpret-trailers <<EOF 310> Signed-off-by: Alice <alice@example.com> 311> EOF 312 313Signed-off-by: Alice <alice@example.com> 314------------ 315 316* Configure a 'fix' trailer with a key that contains a '#' and no 317 space after this character, and show how it works: 318+ 319------------ 320$ git config trailer.separators ":#" 321$ git config trailer.fix.key "Fix #" 322$ echo "subject" | git interpret-trailers --trailer fix=42 323subject 324 325Fix #42 326------------ 327 328* Configure a 'see' trailer with a command to show the subject of a 329 commit that is related, and show how it works: 330+ 331------------ 332$ git config trailer.see.key "See-also: " 333$ git config trailer.see.ifExists "replace" 334$ git config trailer.see.ifMissing "doNothing" 335$ git config trailer.see.command "git log -1 --oneline --format=\"%h (%s)\" --abbrev-commit --abbrev=14 \$ARG" 336$ git interpret-trailers <<EOF 337> subject 338> 339> message 340> 341> see: HEAD~2 342> EOF 343subject 344 345message 346 347See-also: fe3187489d69c4 (subject of related commit) 348------------ 349 350* Configure a commit template with some trailers with empty values 351 (using sed to show and keep the trailing spaces at the end of the 352 trailers), then configure a commit-msg hook that uses 353 'git interpret-trailers' to remove trailers with empty values and 354 to add a 'git-version' trailer: 355+ 356------------ 357$ sed -e 's/ Z$/ /' >commit_template.txt <<EOF 358> ***subject*** 359> 360> ***message*** 361> 362> Fixes: Z 363> Cc: Z 364> Reviewed-by: Z 365> Signed-off-by: Z 366> EOF 367$ git config commit.template commit_template.txt 368$ cat >.git/hooks/commit-msg <<EOF 369> #!/bin/sh 370> git interpret-trailers --trim-empty --trailer "git-version: \$(git describe)" "\$1" > "\$1.new" 371> mv "\$1.new" "\$1" 372> EOF 373$ chmod +x .git/hooks/commit-msg 374------------ 375 376SEE ALSO 377-------- 378linkgit:git-commit[1], linkgit:git-format-patch[1], linkgit:git-config[1] 379 380GIT 381--- 382Part of the linkgit:git[1] suite