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' [--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 contain a colon (by default), where 52the group is preceded by one or more empty (or whitespace-only) lines. 53The group must either be at the end of the message or be the last 54non-whitespace lines before a line that starts with '---'. Such three 55minus signs start the patch part of the message. 56 57When reading trailers, there can be whitespaces before and after the 58token, the separator and the value. There can also be whitespaces 59inside the token and the value. 60 61Note that 'trailers' do not follow and are not intended to follow many 62rules for RFC 822 headers. For example they do not follow the line 63folding rules, the encoding rules and probably many other rules. 64 65OPTIONS 66------- 67--trim-empty:: 68 If the <value> part of any trailer contains only whitespace, 69 the whole trailer will be removed from the resulting message. 70 This applies to existing trailers as well as new trailers. 71 72--trailer <token>[(=|:)<value>]:: 73 Specify a (<token>, <value>) pair that should be applied as a 74 trailer to the input messages. See the description of this 75 command. 76 77CONFIGURATION VARIABLES 78----------------------- 79 80trailer.separators:: 81 This option tells which characters are recognized as trailer 82 separators. By default only ':' is recognized as a trailer 83 separator, except that '=' is always accepted on the command 84 line for compatibility with other git commands. 85+ 86The first character given by this option will be the default character 87used when another separator is not specified in the config for this 88trailer. 89+ 90For example, if the value for this option is "%=$", then only lines 91using the format '<token><sep><value>' with <sep> containing '%', '=' 92or '$' and then spaces will be considered trailers. And '%' will be 93the default separator used, so by default trailers will appear like: 94'<token>% <value>' (one percent sign and one space will appear between 95the token and the value). 96 97trailer.where:: 98 This option tells where a new trailer will be added. 99+ 100This can be `end`, which is the default, `start`, `after` or `before`. 101+ 102If it is `end`, then each new trailer will appear at the end of the 103existing trailers. 104+ 105If it is `start`, then each new trailer will appear at the start, 106instead of the end, of the existing trailers. 107+ 108If it is `after`, then each new trailer will appear just after the 109last trailer with the same <token>. 110+ 111If it is `before`, then each new trailer will appear just before the 112first trailer with the same <token>. 113 114trailer.ifexists:: 115 This option makes it possible to choose what action will be 116 performed when there is already at least one trailer with the 117 same <token> in the message. 118+ 119The valid values for this option are: `addIfDifferentNeighbor` (this 120is the default), `addIfDifferent`, `add`, `overwrite` or `doNothing`. 121+ 122With `addIfDifferentNeighbor`, a new trailer will be added only if no 123trailer with the same (<token>, <value>) pair is above or below the line 124where the new trailer will be added. 125+ 126With `addIfDifferent`, a new trailer will be added only if no trailer 127with the same (<token>, <value>) pair is already in the message. 128+ 129With `add`, a new trailer will be added, even if some trailers with 130the same (<token>, <value>) pair are already in the message. 131+ 132With `replace`, an existing trailer with the same <token> will be 133deleted and the new trailer will be added. The deleted trailer will be 134the closest one (with the same <token>) to the place where the new one 135will be added. 136+ 137With `doNothing`, nothing will be done; that is no new trailer will be 138added if there is already one with the same <token> in the message. 139 140trailer.ifmissing:: 141 This option makes it possible to choose what action will be 142 performed when there is not yet any trailer with the same 143 <token> in the message. 144+ 145The valid values for this option are: `add` (this is the default) and 146`doNothing`. 147+ 148With `add`, a new trailer will be added. 149+ 150With `doNothing`, nothing will be done. 151 152trailer.<token>.key:: 153 This `key` will be used instead of <token> in the trailer. At 154 the end of this key, a separator can appear and then some 155 space characters. By default the only valid separator is ':', 156 but this can be changed using the `trailer.separators` config 157 variable. 158+ 159If there is a separator, then the key will be used instead of both the 160<token> and the default separator when adding the trailer. 161 162trailer.<token>.where:: 163 This option takes the same values as the 'trailer.where' 164 configuration variable and it overrides what is specified by 165 that option for trailers with the specified <token>. 166 167trailer.<token>.ifexist:: 168 This option takes the same values as the 'trailer.ifexist' 169 configuration variable and it overrides what is specified by 170 that option for trailers with the specified <token>. 171 172trailer.<token>.ifmissing:: 173 This option takes the same values as the 'trailer.ifmissing' 174 configuration variable and it overrides what is specified by 175 that option for trailers with the specified <token>. 176 177trailer.<token>.command:: 178 This option can be used to specify a shell command that will 179 be called to automatically add or modify a trailer with the 180 specified <token>. 181+ 182When this option is specified, the behavior is as if a special 183'<token>=<value>' argument were added at the beginning of the command 184line, where <value> is taken to be the standard output of the 185specified command with any leading and trailing whitespace trimmed 186off. 187+ 188If the command contains the `$ARG` string, this string will be 189replaced with the <value> part of an existing trailer with the same 190<token>, if any, before the command is launched. 191+ 192If some '<token>=<value>' arguments are also passed on the command 193line, when a 'trailer.<token>.command' is configured, the command will 194also be executed for each of these arguments. And the <value> part of 195these arguments, if any, will be used to replace the `$ARG` string in 196the command. 197 198EXAMPLES 199-------- 200 201* Configure a 'sign' trailer with a 'Signed-off-by' key, and then 202 add two of these trailers to a message: 203+ 204------------ 205$ git config trailer.sign.key "Signed-off-by" 206$ cat msg.txt 207subject 208 209message 210$ cat msg.txt | git interpret-trailers --trailer 'sign: Alice <alice@example.com>' --trailer 'sign: Bob <bob@example.com>' 211subject 212 213message 214 215Signed-off-by: Alice <alice@example.com> 216Signed-off-by: Bob <bob@example.com> 217------------ 218 219* Extract the last commit as a patch, and add a 'Cc' and a 220 'Reviewed-by' trailer to it: 221+ 222------------ 223$ git format-patch -1 2240001-foo.patch 225$ git interpret-trailers --trailer 'Cc: Alice <alice@example.com>' --trailer 'Reviewed-by: Bob <bob@example.com>' 0001-foo.patch >0001-bar.patch 226------------ 227 228* Configure a 'sign' trailer with a command to automatically add a 229 'Signed-off-by: ' with the author information only if there is no 230 'Signed-off-by: ' already, and show how it works: 231+ 232------------ 233$ git config trailer.sign.key "Signed-off-by: " 234$ git config trailer.sign.ifmissing add 235$ git config trailer.sign.ifexists doNothing 236$ git config trailer.sign.command 'echo "$(git config user.name) <$(git config user.email)>"' 237$ git interpret-trailers <<EOF 238> EOF 239 240Signed-off-by: Bob <bob@example.com> 241$ git interpret-trailers <<EOF 242> Signed-off-by: Alice <alice@example.com> 243> EOF 244 245Signed-off-by: Alice <alice@example.com> 246------------ 247 248* Configure a 'fix' trailer with a key that contains a '#' and no 249 space after this character, and show how it works: 250+ 251------------ 252$ git config trailer.separators ":#" 253$ git config trailer.fix.key "Fix #" 254$ echo "subject" | git interpret-trailers --trailer fix=42 255subject 256 257Fix #42 258------------ 259 260* Configure a 'see' trailer with a command to show the subject of a 261 commit that is related, and show how it works: 262+ 263------------ 264$ git config trailer.see.key "See-also: " 265$ git config trailer.see.ifExists "replace" 266$ git config trailer.see.ifMissing "doNothing" 267$ git config trailer.see.command "git log -1 --oneline --format=\"%h (%s)\" --abbrev-commit --abbrev=14 \$ARG" 268$ git interpret-trailers <<EOF 269> subject 270> 271> message 272> 273> see: HEAD~2 274> EOF 275subject 276 277message 278 279See-also: fe3187489d69c4 (subject of related commit) 280------------ 281 282* Configure a commit template with some trailers with empty values 283 (using sed to show and keep the trailing spaces at the end of the 284 trailers), then configure a commit-msg hook that uses 285 'git interpret-trailers' to remove trailers with empty values and 286 to add a 'git-version' trailer: 287+ 288------------ 289$ sed -e 's/ Z$/ /' >commit_template.txt <<EOF 290> ***subject*** 291> 292> ***message*** 293> 294> Fixes: Z 295> Cc: Z 296> Reviewed-by: Z 297> Signed-off-by: Z 298> EOF 299$ git config commit.template commit_template.txt 300$ cat >.git/hooks/commit-msg <<EOF 301> #!/bin/sh 302> git interpret-trailers --trim-empty --trailer "git-version: \$(git describe)" "\$1" > "\$1.new" 303> mv "\$1.new" "\$1" 304> EOF 305$ chmod +x .git/hooks/commit-msg 306------------ 307 308SEE ALSO 309-------- 310linkgit:git-commit[1], linkgit:git-format-patch[1], linkgit:git-config[1] 311 312GIT 313--- 314Part of the linkgit:git[1] suite