Documentation / git-interpret-trailers.txton commit Merge branch 'mh/reflog-expire' into mh/ref-trans-value-check (61c9475)
   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 apply 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