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 83CONFIGURATION VARIABLES 84----------------------- 85 86trailer.separators:: 87 This option tells which characters are recognized as trailer 88 separators. By default only ':' is recognized as a trailer 89 separator, except that '=' is always accepted on the command 90 line for compatibility with other git commands. 91+ 92The first character given by this option will be the default character 93used when another separator is not specified in the config for this 94trailer. 95+ 96For example, if the value for this option is "%=$", then only lines 97using the format '<token><sep><value>' with <sep> containing '%', '=' 98or '$' and then spaces will be considered trailers. And '%' will be 99the default separator used, so by default trailers will appear like: 100'<token>% <value>' (one percent sign and one space will appear between 101the token and the value). 102 103trailer.where:: 104 This option tells where a new trailer will be added. 105+ 106This can be `end`, which is the default, `start`, `after` or `before`. 107+ 108If it is `end`, then each new trailer will appear at the end of the 109existing trailers. 110+ 111If it is `start`, then each new trailer will appear at the start, 112instead of the end, of the existing trailers. 113+ 114If it is `after`, then each new trailer will appear just after the 115last trailer with the same <token>. 116+ 117If it is `before`, then each new trailer will appear just before the 118first trailer with the same <token>. 119 120trailer.ifexists:: 121 This option makes it possible to choose what action will be 122 performed when there is already at least one trailer with the 123 same <token> in the message. 124+ 125The valid values for this option are: `addIfDifferentNeighbor` (this 126is the default), `addIfDifferent`, `add`, `overwrite` or `doNothing`. 127+ 128With `addIfDifferentNeighbor`, a new trailer will be added only if no 129trailer with the same (<token>, <value>) pair is above or below the line 130where the new trailer will be added. 131+ 132With `addIfDifferent`, a new trailer will be added only if no trailer 133with the same (<token>, <value>) pair is already in the message. 134+ 135With `add`, a new trailer will be added, even if some trailers with 136the same (<token>, <value>) pair are already in the message. 137+ 138With `replace`, an existing trailer with the same <token> will be 139deleted and the new trailer will be added. The deleted trailer will be 140the closest one (with the same <token>) to the place where the new one 141will be added. 142+ 143With `doNothing`, nothing will be done; that is no new trailer will be 144added if there is already one with the same <token> in the message. 145 146trailer.ifmissing:: 147 This option makes it possible to choose what action will be 148 performed when there is not yet any trailer with the same 149 <token> in the message. 150+ 151The valid values for this option are: `add` (this is the default) and 152`doNothing`. 153+ 154With `add`, a new trailer will be added. 155+ 156With `doNothing`, nothing will be done. 157 158trailer.<token>.key:: 159 This `key` will be used instead of <token> in the trailer. At 160 the end of this key, a separator can appear and then some 161 space characters. By default the only valid separator is ':', 162 but this can be changed using the `trailer.separators` config 163 variable. 164+ 165If there is a separator, then the key will be used instead of both the 166<token> and the default separator when adding the trailer. 167 168trailer.<token>.where:: 169 This option takes the same values as the 'trailer.where' 170 configuration variable and it overrides what is specified by 171 that option for trailers with the specified <token>. 172 173trailer.<token>.ifexist:: 174 This option takes the same values as the 'trailer.ifexist' 175 configuration variable and it overrides what is specified by 176 that option for trailers with the specified <token>. 177 178trailer.<token>.ifmissing:: 179 This option takes the same values as the 'trailer.ifmissing' 180 configuration variable and it overrides what is specified by 181 that option for trailers with the specified <token>. 182 183trailer.<token>.command:: 184 This option can be used to specify a shell command that will 185 be called to automatically add or modify a trailer with the 186 specified <token>. 187+ 188When this option is specified, the behavior is as if a special 189'<token>=<value>' argument were added at the beginning of the command 190line, where <value> is taken to be the standard output of the 191specified command with any leading and trailing whitespace trimmed 192off. 193+ 194If the command contains the `$ARG` string, this string will be 195replaced with the <value> part of an existing trailer with the same 196<token>, if any, before the command is launched. 197+ 198If some '<token>=<value>' arguments are also passed on the command 199line, when a 'trailer.<token>.command' is configured, the command will 200also be executed for each of these arguments. And the <value> part of 201these arguments, if any, will be used to replace the `$ARG` string in 202the command. 203 204EXAMPLES 205-------- 206 207* Configure a 'sign' trailer with a 'Signed-off-by' key, and then 208 add two of these trailers to a message: 209+ 210------------ 211$ git config trailer.sign.key "Signed-off-by" 212$ cat msg.txt 213subject 214 215message 216$ cat msg.txt | git interpret-trailers --trailer 'sign: Alice <alice@example.com>' --trailer 'sign: Bob <bob@example.com>' 217subject 218 219message 220 221Signed-off-by: Alice <alice@example.com> 222Signed-off-by: Bob <bob@example.com> 223------------ 224 225* Use the `--in-place` option to edit a message file in place: 226+ 227------------ 228$ cat msg.txt 229subject 230 231message 232 233Signed-off-by: Bob <bob@example.com> 234$ git interpret-trailers --trailer 'Acked-by: Alice <alice@example.com>' --in-place msg.txt 235$ cat msg.txt 236subject 237 238message 239 240Signed-off-by: Bob <bob@example.com> 241Acked-by: Alice <alice@example.com> 242------------ 243 244* Extract the last commit as a patch, and add a 'Cc' and a 245 'Reviewed-by' trailer to it: 246+ 247------------ 248$ git format-patch -1 2490001-foo.patch 250$ git interpret-trailers --trailer 'Cc: Alice <alice@example.com>' --trailer 'Reviewed-by: Bob <bob@example.com>' 0001-foo.patch >0001-bar.patch 251------------ 252 253* Configure a 'sign' trailer with a command to automatically add a 254 'Signed-off-by: ' with the author information only if there is no 255 'Signed-off-by: ' already, and show how it works: 256+ 257------------ 258$ git config trailer.sign.key "Signed-off-by: " 259$ git config trailer.sign.ifmissing add 260$ git config trailer.sign.ifexists doNothing 261$ git config trailer.sign.command 'echo "$(git config user.name) <$(git config user.email)>"' 262$ git interpret-trailers <<EOF 263> EOF 264 265Signed-off-by: Bob <bob@example.com> 266$ git interpret-trailers <<EOF 267> Signed-off-by: Alice <alice@example.com> 268> EOF 269 270Signed-off-by: Alice <alice@example.com> 271------------ 272 273* Configure a 'fix' trailer with a key that contains a '#' and no 274 space after this character, and show how it works: 275+ 276------------ 277$ git config trailer.separators ":#" 278$ git config trailer.fix.key "Fix #" 279$ echo "subject" | git interpret-trailers --trailer fix=42 280subject 281 282Fix #42 283------------ 284 285* Configure a 'see' trailer with a command to show the subject of a 286 commit that is related, and show how it works: 287+ 288------------ 289$ git config trailer.see.key "See-also: " 290$ git config trailer.see.ifExists "replace" 291$ git config trailer.see.ifMissing "doNothing" 292$ git config trailer.see.command "git log -1 --oneline --format=\"%h (%s)\" --abbrev-commit --abbrev=14 \$ARG" 293$ git interpret-trailers <<EOF 294> subject 295> 296> message 297> 298> see: HEAD~2 299> EOF 300subject 301 302message 303 304See-also: fe3187489d69c4 (subject of related commit) 305------------ 306 307* Configure a commit template with some trailers with empty values 308 (using sed to show and keep the trailing spaces at the end of the 309 trailers), then configure a commit-msg hook that uses 310 'git interpret-trailers' to remove trailers with empty values and 311 to add a 'git-version' trailer: 312+ 313------------ 314$ sed -e 's/ Z$/ /' >commit_template.txt <<EOF 315> ***subject*** 316> 317> ***message*** 318> 319> Fixes: Z 320> Cc: Z 321> Reviewed-by: Z 322> Signed-off-by: Z 323> EOF 324$ git config commit.template commit_template.txt 325$ cat >.git/hooks/commit-msg <<EOF 326> #!/bin/sh 327> git interpret-trailers --trim-empty --trailer "git-version: \$(git describe)" "\$1" > "\$1.new" 328> mv "\$1.new" "\$1" 329> EOF 330$ chmod +x .git/hooks/commit-msg 331------------ 332 333SEE ALSO 334-------- 335linkgit:git-commit[1], linkgit:git-format-patch[1], linkgit:git-config[1] 336 337GIT 338--- 339Part of the linkgit:git[1] suite