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, the 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) are 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 '---'. Such three 60minus signs start the patch part of the message. 61 62When reading trailers, there can be whitespaces after the 63token, the separator and the value. There can also be whitespaces 64inside the token and the value. The value may be split over multiple lines with 65each subsequent line starting with whitespace, like the "folding" in RFC 822. 66 67Note that 'trailers' do not follow and are not intended to follow many 68rules for RFC 822 headers. For example they do not follow 69the encoding rules and probably many other rules. 70 71OPTIONS 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 102CONFIGURATION VARIABLES 103----------------------- 104 105trailer.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+ 111The first character given by this option will be the default character 112used when another separator is not specified in the config for this 113trailer. 114+ 115For example, if the value for this option is "%=$", then only lines 116using the format '<token><sep><value>' with <sep> containing '%', '=' 117or '$' and then spaces will be considered trailers. And '%' will be 118the default separator used, so by default trailers will appear like: 119'<token>% <value>' (one percent sign and one space will appear between 120the token and the value). 121 122trailer.where:: 123 This option tells where a new trailer will be added. 124+ 125This can be `end`, which is the default, `start`, `after` or `before`. 126+ 127If it is `end`, then each new trailer will appear at the end of the 128existing trailers. 129+ 130If it is `start`, then each new trailer will appear at the start, 131instead of the end, of the existing trailers. 132+ 133If it is `after`, then each new trailer will appear just after the 134last trailer with the same <token>. 135+ 136If it is `before`, then each new trailer will appear just before the 137first trailer with the same <token>. 138 139trailer.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+ 144The valid values for this option are: `addIfDifferentNeighbor` (this 145is the default), `addIfDifferent`, `add`, `replace` or `doNothing`. 146+ 147With `addIfDifferentNeighbor`, a new trailer will be added only if no 148trailer with the same (<token>, <value>) pair is above or below the line 149where the new trailer will be added. 150+ 151With `addIfDifferent`, a new trailer will be added only if no trailer 152with the same (<token>, <value>) pair is already in the message. 153+ 154With `add`, a new trailer will be added, even if some trailers with 155the same (<token>, <value>) pair are already in the message. 156+ 157With `replace`, an existing trailer with the same <token> will be 158deleted and the new trailer will be added. The deleted trailer will be 159the closest one (with the same <token>) to the place where the new one 160will be added. 161+ 162With `doNothing`, nothing will be done; that is no new trailer will be 163added if there is already one with the same <token> in the message. 164 165trailer.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+ 170The valid values for this option are: `add` (this is the default) and 171`doNothing`. 172+ 173With `add`, a new trailer will be added. 174+ 175With `doNothing`, nothing will be done. 176 177trailer.<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+ 184If 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 187trailer.<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 192trailer.<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 197trailer.<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 202trailer.<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+ 207When this option is specified, the behavior is as if a special 208'<token>=<value>' argument were added at the beginning of the command 209line, where <value> is taken to be the standard output of the 210specified command with any leading and trailing whitespace trimmed 211off. 212+ 213If the command contains the `$ARG` string, this string will be 214replaced with the <value> part of an existing trailer with the same 215<token>, if any, before the command is launched. 216+ 217If some '<token>=<value>' arguments are also passed on the command 218line, when a 'trailer.<token>.command' is configured, the command will 219also be executed for each of these arguments. And the <value> part of 220these arguments, if any, will be used to replace the `$ARG` string in 221the command. 222 223EXAMPLES 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 232subject 233 234message 235$ cat msg.txt | git interpret-trailers --trailer 'sign: Alice <alice@example.com>' --trailer 'sign: Bob <bob@example.com>' 236subject 237 238message 239 240Signed-off-by: Alice <alice@example.com> 241Signed-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 248subject 249 250message 251 252Signed-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 255subject 256 257message 258 259Signed-off-by: Bob <bob@example.com> 260Acked-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 2680001-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 284Signed-off-by: Bob <bob@example.com> 285$ git interpret-trailers <<EOF 286> Signed-off-by: Alice <alice@example.com> 287> EOF 288 289Signed-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 299subject 300 301Fix #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 319subject 320 321message 322 323See-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 352SEE ALSO 353-------- 354linkgit:git-commit[1], linkgit:git-format-patch[1], linkgit:git-config[1] 355 356GIT 357--- 358Part of the linkgit:git[1] suite