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 86--only-input:: 87 Output only trailers that exist in the input; do not add any 88 from the command-line or by following configured `trailer.*` 89 rules. 90 91CONFIGURATION VARIABLES 92----------------------- 93 94trailer.separators:: 95 This option tells which characters are recognized as trailer 96 separators. By default only ':' is recognized as a trailer 97 separator, except that '=' is always accepted on the command 98 line for compatibility with other git commands. 99+ 100The first character given by this option will be the default character 101used when another separator is not specified in the config for this 102trailer. 103+ 104For example, if the value for this option is "%=$", then only lines 105using the format '<token><sep><value>' with <sep> containing '%', '=' 106or '$' and then spaces will be considered trailers. And '%' will be 107the default separator used, so by default trailers will appear like: 108'<token>% <value>' (one percent sign and one space will appear between 109the token and the value). 110 111trailer.where:: 112 This option tells where a new trailer will be added. 113+ 114This can be `end`, which is the default, `start`, `after` or `before`. 115+ 116If it is `end`, then each new trailer will appear at the end of the 117existing trailers. 118+ 119If it is `start`, then each new trailer will appear at the start, 120instead of the end, of the existing trailers. 121+ 122If it is `after`, then each new trailer will appear just after the 123last trailer with the same <token>. 124+ 125If it is `before`, then each new trailer will appear just before the 126first trailer with the same <token>. 127 128trailer.ifexists:: 129 This option makes it possible to choose what action will be 130 performed when there is already at least one trailer with the 131 same <token> in the message. 132+ 133The valid values for this option are: `addIfDifferentNeighbor` (this 134is the default), `addIfDifferent`, `add`, `replace` or `doNothing`. 135+ 136With `addIfDifferentNeighbor`, a new trailer will be added only if no 137trailer with the same (<token>, <value>) pair is above or below the line 138where the new trailer will be added. 139+ 140With `addIfDifferent`, a new trailer will be added only if no trailer 141with the same (<token>, <value>) pair is already in the message. 142+ 143With `add`, a new trailer will be added, even if some trailers with 144the same (<token>, <value>) pair are already in the message. 145+ 146With `replace`, an existing trailer with the same <token> will be 147deleted and the new trailer will be added. The deleted trailer will be 148the closest one (with the same <token>) to the place where the new one 149will be added. 150+ 151With `doNothing`, nothing will be done; that is no new trailer will be 152added if there is already one with the same <token> in the message. 153 154trailer.ifmissing:: 155 This option makes it possible to choose what action will be 156 performed when there is not yet any trailer with the same 157 <token> in the message. 158+ 159The valid values for this option are: `add` (this is the default) and 160`doNothing`. 161+ 162With `add`, a new trailer will be added. 163+ 164With `doNothing`, nothing will be done. 165 166trailer.<token>.key:: 167 This `key` will be used instead of <token> in the trailer. At 168 the end of this key, a separator can appear and then some 169 space characters. By default the only valid separator is ':', 170 but this can be changed using the `trailer.separators` config 171 variable. 172+ 173If there is a separator, then the key will be used instead of both the 174<token> and the default separator when adding the trailer. 175 176trailer.<token>.where:: 177 This option takes the same values as the 'trailer.where' 178 configuration variable and it overrides what is specified by 179 that option for trailers with the specified <token>. 180 181trailer.<token>.ifexist:: 182 This option takes the same values as the 'trailer.ifexist' 183 configuration variable and it overrides what is specified by 184 that option for trailers with the specified <token>. 185 186trailer.<token>.ifmissing:: 187 This option takes the same values as the 'trailer.ifmissing' 188 configuration variable and it overrides what is specified by 189 that option for trailers with the specified <token>. 190 191trailer.<token>.command:: 192 This option can be used to specify a shell command that will 193 be called to automatically add or modify a trailer with the 194 specified <token>. 195+ 196When this option is specified, the behavior is as if a special 197'<token>=<value>' argument were added at the beginning of the command 198line, where <value> is taken to be the standard output of the 199specified command with any leading and trailing whitespace trimmed 200off. 201+ 202If the command contains the `$ARG` string, this string will be 203replaced with the <value> part of an existing trailer with the same 204<token>, if any, before the command is launched. 205+ 206If some '<token>=<value>' arguments are also passed on the command 207line, when a 'trailer.<token>.command' is configured, the command will 208also be executed for each of these arguments. And the <value> part of 209these arguments, if any, will be used to replace the `$ARG` string in 210the command. 211 212EXAMPLES 213-------- 214 215* Configure a 'sign' trailer with a 'Signed-off-by' key, and then 216 add two of these trailers to a message: 217+ 218------------ 219$ git config trailer.sign.key "Signed-off-by" 220$ cat msg.txt 221subject 222 223message 224$ cat msg.txt | git interpret-trailers --trailer 'sign: Alice <alice@example.com>' --trailer 'sign: Bob <bob@example.com>' 225subject 226 227message 228 229Signed-off-by: Alice <alice@example.com> 230Signed-off-by: Bob <bob@example.com> 231------------ 232 233* Use the `--in-place` option to edit a message file in place: 234+ 235------------ 236$ cat msg.txt 237subject 238 239message 240 241Signed-off-by: Bob <bob@example.com> 242$ git interpret-trailers --trailer 'Acked-by: Alice <alice@example.com>' --in-place msg.txt 243$ cat msg.txt 244subject 245 246message 247 248Signed-off-by: Bob <bob@example.com> 249Acked-by: Alice <alice@example.com> 250------------ 251 252* Extract the last commit as a patch, and add a 'Cc' and a 253 'Reviewed-by' trailer to it: 254+ 255------------ 256$ git format-patch -1 2570001-foo.patch 258$ git interpret-trailers --trailer 'Cc: Alice <alice@example.com>' --trailer 'Reviewed-by: Bob <bob@example.com>' 0001-foo.patch >0001-bar.patch 259------------ 260 261* Configure a 'sign' trailer with a command to automatically add a 262 'Signed-off-by: ' with the author information only if there is no 263 'Signed-off-by: ' already, and show how it works: 264+ 265------------ 266$ git config trailer.sign.key "Signed-off-by: " 267$ git config trailer.sign.ifmissing add 268$ git config trailer.sign.ifexists doNothing 269$ git config trailer.sign.command 'echo "$(git config user.name) <$(git config user.email)>"' 270$ git interpret-trailers <<EOF 271> EOF 272 273Signed-off-by: Bob <bob@example.com> 274$ git interpret-trailers <<EOF 275> Signed-off-by: Alice <alice@example.com> 276> EOF 277 278Signed-off-by: Alice <alice@example.com> 279------------ 280 281* Configure a 'fix' trailer with a key that contains a '#' and no 282 space after this character, and show how it works: 283+ 284------------ 285$ git config trailer.separators ":#" 286$ git config trailer.fix.key "Fix #" 287$ echo "subject" | git interpret-trailers --trailer fix=42 288subject 289 290Fix #42 291------------ 292 293* Configure a 'see' trailer with a command to show the subject of a 294 commit that is related, and show how it works: 295+ 296------------ 297$ git config trailer.see.key "See-also: " 298$ git config trailer.see.ifExists "replace" 299$ git config trailer.see.ifMissing "doNothing" 300$ git config trailer.see.command "git log -1 --oneline --format=\"%h (%s)\" --abbrev-commit --abbrev=14 \$ARG" 301$ git interpret-trailers <<EOF 302> subject 303> 304> message 305> 306> see: HEAD~2 307> EOF 308subject 309 310message 311 312See-also: fe3187489d69c4 (subject of related commit) 313------------ 314 315* Configure a commit template with some trailers with empty values 316 (using sed to show and keep the trailing spaces at the end of the 317 trailers), then configure a commit-msg hook that uses 318 'git interpret-trailers' to remove trailers with empty values and 319 to add a 'git-version' trailer: 320+ 321------------ 322$ sed -e 's/ Z$/ /' >commit_template.txt <<EOF 323> ***subject*** 324> 325> ***message*** 326> 327> Fixes: Z 328> Cc: Z 329> Reviewed-by: Z 330> Signed-off-by: Z 331> EOF 332$ git config commit.template commit_template.txt 333$ cat >.git/hooks/commit-msg <<EOF 334> #!/bin/sh 335> git interpret-trailers --trim-empty --trailer "git-version: \$(git describe)" "\$1" > "\$1.new" 336> mv "\$1.new" "\$1" 337> EOF 338$ chmod +x .git/hooks/commit-msg 339------------ 340 341SEE ALSO 342-------- 343linkgit:git-commit[1], linkgit:git-format-patch[1], linkgit:git-config[1] 344 345GIT 346--- 347Part of the linkgit:git[1] suite