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 trailer and consists of at least 25% trailers. 53The group must be preceded by one or more empty (or whitespace-only) lines. 54The group must either be at the end of the message or be the last 55non-whitespace lines before a line that starts with '---'. Such three 56minus signs start the patch part of the message. 57 58When reading trailers, there can be whitespaces before and after the 59token, the separator and the value. There can also be whitespaces 60inside the token and the value. 61 62Note that 'trailers' do not follow and are not intended to follow many 63rules for RFC 822 headers. For example they do not follow the line 64folding rules, the encoding rules and probably many other rules. 65 66OPTIONS 67------- 68--in-place:: 69 Edit the files in place. 70 71--trim-empty:: 72 If the <value> part of any trailer contains only whitespace, 73 the whole trailer will be removed from the resulting message. 74 This applies to existing trailers as well as new trailers. 75 76--trailer <token>[(=|:)<value>]:: 77 Specify a (<token>, <value>) pair that should be applied as a 78 trailer to the input messages. See the description of this 79 command. 80 81CONFIGURATION VARIABLES 82----------------------- 83 84trailer.separators:: 85 This option tells which characters are recognized as trailer 86 separators. By default only ':' is recognized as a trailer 87 separator, except that '=' is always accepted on the command 88 line for compatibility with other git commands. 89+ 90The first character given by this option will be the default character 91used when another separator is not specified in the config for this 92trailer. 93+ 94For example, if the value for this option is "%=$", then only lines 95using the format '<token><sep><value>' with <sep> containing '%', '=' 96or '$' and then spaces will be considered trailers. And '%' will be 97the default separator used, so by default trailers will appear like: 98'<token>% <value>' (one percent sign and one space will appear between 99the token and the value). 100 101trailer.where:: 102 This option tells where a new trailer will be added. 103+ 104This can be `end`, which is the default, `start`, `after` or `before`. 105+ 106If it is `end`, then each new trailer will appear at the end of the 107existing trailers. 108+ 109If it is `start`, then each new trailer will appear at the start, 110instead of the end, of the existing trailers. 111+ 112If it is `after`, then each new trailer will appear just after the 113last trailer with the same <token>. 114+ 115If it is `before`, then each new trailer will appear just before the 116first trailer with the same <token>. 117 118trailer.ifexists:: 119 This option makes it possible to choose what action will be 120 performed when there is already at least one trailer with the 121 same <token> in the message. 122+ 123The valid values for this option are: `addIfDifferentNeighbor` (this 124is the default), `addIfDifferent`, `add`, `overwrite` or `doNothing`. 125+ 126With `addIfDifferentNeighbor`, a new trailer will be added only if no 127trailer with the same (<token>, <value>) pair is above or below the line 128where the new trailer will be added. 129+ 130With `addIfDifferent`, a new trailer will be added only if no trailer 131with the same (<token>, <value>) pair is already in the message. 132+ 133With `add`, a new trailer will be added, even if some trailers with 134the same (<token>, <value>) pair are already in the message. 135+ 136With `replace`, an existing trailer with the same <token> will be 137deleted and the new trailer will be added. The deleted trailer will be 138the closest one (with the same <token>) to the place where the new one 139will be added. 140+ 141With `doNothing`, nothing will be done; that is no new trailer will be 142added if there is already one with the same <token> in the message. 143 144trailer.ifmissing:: 145 This option makes it possible to choose what action will be 146 performed when there is not yet any trailer with the same 147 <token> in the message. 148+ 149The valid values for this option are: `add` (this is the default) and 150`doNothing`. 151+ 152With `add`, a new trailer will be added. 153+ 154With `doNothing`, nothing will be done. 155 156trailer.<token>.key:: 157 This `key` will be used instead of <token> in the trailer. At 158 the end of this key, a separator can appear and then some 159 space characters. By default the only valid separator is ':', 160 but this can be changed using the `trailer.separators` config 161 variable. 162+ 163If there is a separator, then the key will be used instead of both the 164<token> and the default separator when adding the trailer. 165 166trailer.<token>.where:: 167 This option takes the same values as the 'trailer.where' 168 configuration variable and it overrides what is specified by 169 that option for trailers with the specified <token>. 170 171trailer.<token>.ifexist:: 172 This option takes the same values as the 'trailer.ifexist' 173 configuration variable and it overrides what is specified by 174 that option for trailers with the specified <token>. 175 176trailer.<token>.ifmissing:: 177 This option takes the same values as the 'trailer.ifmissing' 178 configuration variable and it overrides what is specified by 179 that option for trailers with the specified <token>. 180 181trailer.<token>.command:: 182 This option can be used to specify a shell command that will 183 be called to automatically add or modify a trailer with the 184 specified <token>. 185+ 186When this option is specified, the behavior is as if a special 187'<token>=<value>' argument were added at the beginning of the command 188line, where <value> is taken to be the standard output of the 189specified command with any leading and trailing whitespace trimmed 190off. 191+ 192If the command contains the `$ARG` string, this string will be 193replaced with the <value> part of an existing trailer with the same 194<token>, if any, before the command is launched. 195+ 196If some '<token>=<value>' arguments are also passed on the command 197line, when a 'trailer.<token>.command' is configured, the command will 198also be executed for each of these arguments. And the <value> part of 199these arguments, if any, will be used to replace the `$ARG` string in 200the command. 201 202EXAMPLES 203-------- 204 205* Configure a 'sign' trailer with a 'Signed-off-by' key, and then 206 add two of these trailers to a message: 207+ 208------------ 209$ git config trailer.sign.key "Signed-off-by" 210$ cat msg.txt 211subject 212 213message 214$ cat msg.txt | git interpret-trailers --trailer 'sign: Alice <alice@example.com>' --trailer 'sign: Bob <bob@example.com>' 215subject 216 217message 218 219Signed-off-by: Alice <alice@example.com> 220Signed-off-by: Bob <bob@example.com> 221------------ 222 223* Use the `--in-place` option to edit a message file in place: 224+ 225------------ 226$ cat msg.txt 227subject 228 229message 230 231Signed-off-by: Bob <bob@example.com> 232$ git interpret-trailers --trailer 'Acked-by: Alice <alice@example.com>' --in-place msg.txt 233$ cat msg.txt 234subject 235 236message 237 238Signed-off-by: Bob <bob@example.com> 239Acked-by: Alice <alice@example.com> 240------------ 241 242* Extract the last commit as a patch, and add a 'Cc' and a 243 'Reviewed-by' trailer to it: 244+ 245------------ 246$ git format-patch -1 2470001-foo.patch 248$ git interpret-trailers --trailer 'Cc: Alice <alice@example.com>' --trailer 'Reviewed-by: Bob <bob@example.com>' 0001-foo.patch >0001-bar.patch 249------------ 250 251* Configure a 'sign' trailer with a command to automatically add a 252 'Signed-off-by: ' with the author information only if there is no 253 'Signed-off-by: ' already, and show how it works: 254+ 255------------ 256$ git config trailer.sign.key "Signed-off-by: " 257$ git config trailer.sign.ifmissing add 258$ git config trailer.sign.ifexists doNothing 259$ git config trailer.sign.command 'echo "$(git config user.name) <$(git config user.email)>"' 260$ git interpret-trailers <<EOF 261> EOF 262 263Signed-off-by: Bob <bob@example.com> 264$ git interpret-trailers <<EOF 265> Signed-off-by: Alice <alice@example.com> 266> EOF 267 268Signed-off-by: Alice <alice@example.com> 269------------ 270 271* Configure a 'fix' trailer with a key that contains a '#' and no 272 space after this character, and show how it works: 273+ 274------------ 275$ git config trailer.separators ":#" 276$ git config trailer.fix.key "Fix #" 277$ echo "subject" | git interpret-trailers --trailer fix=42 278subject 279 280Fix #42 281------------ 282 283* Configure a 'see' trailer with a command to show the subject of a 284 commit that is related, and show how it works: 285+ 286------------ 287$ git config trailer.see.key "See-also: " 288$ git config trailer.see.ifExists "replace" 289$ git config trailer.see.ifMissing "doNothing" 290$ git config trailer.see.command "git log -1 --oneline --format=\"%h (%s)\" --abbrev-commit --abbrev=14 \$ARG" 291$ git interpret-trailers <<EOF 292> subject 293> 294> message 295> 296> see: HEAD~2 297> EOF 298subject 299 300message 301 302See-also: fe3187489d69c4 (subject of related commit) 303------------ 304 305* Configure a commit template with some trailers with empty values 306 (using sed to show and keep the trailing spaces at the end of the 307 trailers), then configure a commit-msg hook that uses 308 'git interpret-trailers' to remove trailers with empty values and 309 to add a 'git-version' trailer: 310+ 311------------ 312$ sed -e 's/ Z$/ /' >commit_template.txt <<EOF 313> ***subject*** 314> 315> ***message*** 316> 317> Fixes: Z 318> Cc: Z 319> Reviewed-by: Z 320> Signed-off-by: Z 321> EOF 322$ git config commit.template commit_template.txt 323$ cat >.git/hooks/commit-msg <<EOF 324> #!/bin/sh 325> git interpret-trailers --trim-empty --trailer "git-version: \$(git describe)" "\$1" > "\$1.new" 326> mv "\$1.new" "\$1" 327> EOF 328$ chmod +x .git/hooks/commit-msg 329------------ 330 331SEE ALSO 332-------- 333linkgit:git-commit[1], linkgit:git-format-patch[1], linkgit:git-config[1] 334 335GIT 336--- 337Part of the linkgit:git[1] suite