GIT-INTERPRET-TRAI(1)		  Git Manual		 GIT-INTERPRET-TRAI(1)



NAME
       git-interpret-trailers - Add or parse structured information in commit
       messages

SYNOPSIS
       git interpret-trailers [<options>] [(--trailer <token>[(=|:)<value>])...] [<file>...]
       git interpret-trailers [<options>] [--parse] [<file>...]


DESCRIPTION
       Help parsing or adding trailers lines, that look similar to RFC 822
       e-mail headers, at the end of the otherwise free-form part of a commit
       message.

       This command reads some patches or commit messages from either the
       <file> arguments or the standard input if no <file> is specified. If
       --parse is specified, the output consists of the parsed trailers.

       Otherwise, this command applies the arguments passed using the
       --trailer option, if any, to the commit message part of each input
       file. The result is emitted on the standard output.

       Some configuration variables control the way the --trailer arguments
       are applied to each commit message and the way any existing trailer in
       the commit message is changed. They also make it possible to
       automatically add some trailers.

       By default, a <token>=<value> or <token>:<value> argument given using
       --trailer will be appended after the existing trailers only if the last
       trailer has a different (<token>, <value>) pair (or if there is no
       existing trailer). The <token> and <value> parts will be trimmed to
       remove starting and trailing whitespace, and the resulting trimmed
       <token> and <value> will appear in the message like this:

	   token: value


       This means that the trimmed <token> and <value> will be separated by ':
       ' (one colon followed by one space).

       By default the new trailer will appear at the end of all the existing
       trailers. If there is no existing trailer, the new trailer will appear
       after the commit message part of the output, and, if there is no line
       with only spaces at the end of the commit message part, one blank line
       will be added before the new trailer.

       Existing trailers are extracted from the input message by looking for a
       group of one or more lines that (i) is all trailers, or (ii) contains
       at least one Git-generated or user-configured trailer and consists of
       at least 25% trailers. The group must be preceded by one or more empty
       (or whitespace-only) lines. The group must either be at the end of the
       message or be the last non-whitespace lines before a line that starts
       with --- (followed by a space or the end of the line). Such three minus
       signs start the patch part of the message. See also --no-divider below.

       When reading trailers, there can be no whitespace before or inside the
       token, but any number of regular space and tab characters are allowed
       between the token and the separator. There can be whitespaces before,
       inside or after the value. The value may be split over multiple lines
       with each subsequent line starting with at least one whitespace, like
       the "folding" in RFC 822.

       Note that trailers do not follow and are not intended to follow many
       rules for RFC 822 headers. For example they do not follow the encoding
       rules and probably many other rules.

OPTIONS
       --in-place
	   Edit the files in place.

       --trim-empty
	   If the <value> part of any trailer contains only whitespace, the
	   whole trailer will be removed from the resulting message. This
	   applies to existing trailers as well as new trailers.

       --trailer <token>[(=|:)<value>]
	   Specify a (<token>, <value>) pair that should be applied as a
	   trailer to the input messages. See the description of this command.

       --where <placement>, --no-where
	   Specify where all new trailers will be added. A setting provided
	   with --where overrides all configuration variables and applies to
	   all --trailer options until the next occurrence of --where or
	   --no-where. Possible values are after, before, end or start.

       --if-exists <action>, --no-if-exists
	   Specify what action will be performed when there is already at
	   least one trailer with the same <token> in the message. A setting
	   provided with --if-exists overrides all configuration variables and
	   applies to all --trailer options until the next occurrence of
	   --if-exists or --no-if-exists. Possible actions are addIfDifferent,
	   addIfDifferentNeighbor, add, replace and doNothing.

       --if-missing <action>, --no-if-missing
	   Specify what action will be performed when there is no other
	   trailer with the same <token> in the message. A setting provided
	   with --if-missing overrides all configuration variables and applies
	   to all --trailer options until the next occurrence of --if-missing
	   or --no-if-missing. Possible actions are doNothing or add.

       --only-trailers
	   Output only the trailers, not any other parts of the input.

       --only-input
	   Output only trailers that exist in the input; do not add any from
	   the command-line or by following configured trailer.*  rules.

       --unfold
	   Remove any whitespace-continuation in trailers, so that each
	   trailer appears on a line by itself with its full content.

       --parse
	   A convenience alias for --only-trailers --only-input --unfold.

       --no-divider
	   Do not treat --- as the end of the commit message. Use this when
	   you know your input contains just the commit message itself (and
	   not an email or the output of git format-patch).

CONFIGURATION VARIABLES
       trailer.separators
	   This option tells which characters are recognized as trailer
	   separators. By default only : is recognized as a trailer separator,
	   except that = is always accepted on the command line for
	   compatibility with other git commands.

	   The first character given by this option will be the default
	   character used when another separator is not specified in the
	   config for this trailer.

	   For example, if the value for this option is "%=$", then only lines
	   using the format <token><sep><value> with <sep> containing %, = or
	   $ and then spaces will be considered trailers. And % will be the
	   default separator used, so by default trailers will appear like:
	   <token>% <value> (one percent sign and one space will appear
	   between the token and the value).

       trailer.where
	   This option tells where a new trailer will be added.

	   This can be end, which is the default, start, after or before.

	   If it is end, then each new trailer will appear at the end of the
	   existing trailers.

	   If it is start, then each new trailer will appear at the start,
	   instead of the end, of the existing trailers.

	   If it is after, then each new trailer will appear just after the
	   last trailer with the same <token>.

	   If it is before, then each new trailer will appear just before the
	   first trailer with the same <token>.

       trailer.ifexists
	   This option makes it possible to choose what action will be
	   performed when there is already at least one trailer with the same
	   <token> in the message.

	   The valid values for this option are: addIfDifferentNeighbor (this
	   is the default), addIfDifferent, add, replace or doNothing.

	   With addIfDifferentNeighbor, a new trailer will be added only if no
	   trailer with the same (<token>, <value>) pair is above or below the
	   line where the new trailer will be added.

	   With addIfDifferent, a new trailer will be added only if no trailer
	   with the same (<token>, <value>) pair is already in the message.

	   With add, a new trailer will be added, even if some trailers with
	   the same (<token>, <value>) pair are already in the message.

	   With replace, an existing trailer with the same <token> will be
	   deleted and the new trailer will be added. The deleted trailer will
	   be the closest one (with the same <token>) to the place where the
	   new one will be added.

	   With doNothing, nothing will be done; that is no new trailer will
	   be added if there is already one with the same <token> in the
	   message.

       trailer.ifmissing
	   This option makes it possible to choose what action will be
	   performed when there is not yet any trailer with the same <token>
	   in the message.

	   The valid values for this option are: add (this is the default) and
	   doNothing.

	   With add, a new trailer will be added.

	   With doNothing, nothing will be done.

       trailer.<token>.key
	   This key will be used instead of <token> in the trailer. At the end
	   of this key, a separator can appear and then some space characters.
	   By default the only valid separator is :, but this can be changed
	   using the trailer.separators config variable.

	   If there is a separator, then the key will be used instead of both
	   the <token> and the default separator when adding the trailer.

       trailer.<token>.where
	   This option takes the same values as the trailer.where
	   configuration variable and it overrides what is specified by that
	   option for trailers with the specified <token>.

       trailer.<token>.ifexists
	   This option takes the same values as the trailer.ifexists
	   configuration variable and it overrides what is specified by that
	   option for trailers with the specified <token>.

       trailer.<token>.ifmissing
	   This option takes the same values as the trailer.ifmissing
	   configuration variable and it overrides what is specified by that
	   option for trailers with the specified <token>.

       trailer.<token>.command
	   This option behaves in the same way as trailer.<token>.cmd, except
	   that it doesn't pass anything as argument to the specified command.
	   Instead the first occurrence of substring $ARG is replaced by the
	   value that would be passed as argument.

	   The trailer.<token>.command option has been deprecated in favor of
	   trailer.<token>.cmd due to the fact that $ARG in the user's command
	   is only replaced once and that the original way of replacing $ARG
	   is not safe.

	   When both trailer.<token>.cmd and trailer.<token>.command are given
	   for the same <token>, trailer.<token>.cmd is used and
	   trailer.<token>.command is ignored.

       trailer.<token>.cmd
	   This option can be used to specify a shell command that will be
	   called: once to automatically add a trailer with the specified
	   <token>, and then each time a --trailer <token>=<value> argument to
	   modify the <value> of the trailer that this option would produce.

	   When the specified command is first called to add a trailer with
	   the specified <token>, the behavior is as if a special --trailer
	   <token>=<value> argument was added at the beginning of the "git
	   interpret-trailers" command, where <value> is taken to be the
	   standard output of the command with any leading and trailing
	   whitespace trimmed off.

	   If some --trailer <token>=<value> arguments are also passed on the
	   command line, the command is called again once for each of these
	   arguments with the same <token>. And the <value> part of these
	   arguments, if any, will be passed to the command as its first
	   argument. This way the command can produce a <value> computed from
	   the <value> passed in the --trailer <token>=<value> argument.

EXAMPLES
       o   Configure a sign trailer with a Signed-off-by key, and then add two
	   of these trailers to a message:

	       $ git config trailer.sign.key "Signed-off-by"
	       $ cat msg.txt
	       subject

	       message
	       $ cat msg.txt | git interpret-trailers --trailer 'sign: Alice <alice@example.com>' --trailer 'sign: Bob <bob@example.com>'
	       subject

	       message

	       Signed-off-by: Alice <alice@example.com>
	       Signed-off-by: Bob <bob@example.com>


       o   Use the --in-place option to edit a message file in place:

	       $ cat msg.txt
	       subject

	       message

	       Signed-off-by: Bob <bob@example.com>
	       $ git interpret-trailers --trailer 'Acked-by: Alice <alice@example.com>' --in-place msg.txt
	       $ cat msg.txt
	       subject

	       message

	       Signed-off-by: Bob <bob@example.com>
	       Acked-by: Alice <alice@example.com>


       o   Extract the last commit as a patch, and add a Cc and a Reviewed-by
	   trailer to it:

	       $ git format-patch -1
	       0001-foo.patch
	       $ git interpret-trailers --trailer 'Cc: Alice <alice@example.com>' --trailer 'Reviewed-by: Bob <bob@example.com>' 0001-foo.patch >0001-bar.patch


       o   Configure a sign trailer with a command to automatically add a
	   'Signed-off-by: ' with the author information only if there is no
	   'Signed-off-by: ' already, and show how it works:

	       $ git config trailer.sign.key "Signed-off-by: "
	       $ git config trailer.sign.ifmissing add
	       $ git config trailer.sign.ifexists doNothing
	       $ git config trailer.sign.command 'echo "$(git config user.name) <$(git config user.email)>"'
	       $ git interpret-trailers <<EOF
	       > EOF

	       Signed-off-by: Bob <bob@example.com>
	       $ git interpret-trailers <<EOF
	       > Signed-off-by: Alice <alice@example.com>
	       > EOF

	       Signed-off-by: Alice <alice@example.com>


       o   Configure a fix trailer with a key that contains a # and no space
	   after this character, and show how it works:

	       $ git config trailer.separators ":#"
	       $ git config trailer.fix.key "Fix #"
	       $ echo "subject" | git interpret-trailers --trailer fix=42
	       subject

	       Fix #42


       o   Configure a help trailer with a cmd use a script glog-find-author
	   which search specified author identity from git log in git
	   repository and show how it works:

	       $ cat ~/bin/glog-find-author
	       #!/bin/sh
	       test -n "$1" && git log --author="$1" --pretty="%an <%ae>" -1 || true
	       $ git config trailer.help.key "Helped-by: "
	       $ git config trailer.help.ifExists "addIfDifferentNeighbor"
	       $ git config trailer.help.cmd "~/bin/glog-find-author"
	       $ git interpret-trailers --trailer="help:Junio" --trailer="help:Couder" <<EOF
	       > subject
	       >
	       > message
	       >
	       > EOF
	       subject

	       message

	       Helped-by: Junio C Hamano <gitster@pobox.com>
	       Helped-by: Christian Couder <christian.couder@gmail.com>


       o   Configure a ref trailer with a cmd use a script glog-grep to grep
	   last relevant commit from git log in the git repository and show
	   how it works:

	       $ cat ~/bin/glog-grep
	       #!/bin/sh
	       test -n "$1" && git log --grep "$1" --pretty=reference -1 || true
	       $ git config trailer.ref.key "Reference-to: "
	       $ git config trailer.ref.ifExists "replace"
	       $ git config trailer.ref.cmd "~/bin/glog-grep"
	       $ git interpret-trailers --trailer="ref:Add copyright notices." <<EOF
	       > subject
	       >
	       > message
	       >
	       > EOF
	       subject

	       message

	       Reference-to: 8bc9a0c769 (Add copyright notices., 2005-04-07)


       o   Configure a see trailer with a command to show the subject of a
	   commit that is related, and show how it works:

	       $ git config trailer.see.key "See-also: "
	       $ git config trailer.see.ifExists "replace"
	       $ git config trailer.see.ifMissing "doNothing"
	       $ git config trailer.see.command "git log -1 --oneline --format=\"%h (%s)\" --abbrev-commit --abbrev=14 \$ARG"
	       $ git interpret-trailers <<EOF
	       > subject
	       >
	       > message
	       >
	       > see: HEAD~2
	       > EOF
	       subject

	       message

	       See-also: fe3187489d69c4 (subject of related commit)


       o   Configure a commit template with some trailers with empty values
	   (using sed to show and keep the trailing spaces at the end of the
	   trailers), then configure a commit-msg hook that uses git
	   interpret-trailers to remove trailers with empty values and to add
	   a git-version trailer:

	       $ sed -e 's/ Z$/ /' >commit_template.txt <<EOF
	       > ***subject***
	       >
	       > ***message***
	       >
	       > Fixes: Z
	       > Cc: Z
	       > Reviewed-by: Z
	       > Signed-off-by: Z
	       > EOF
	       $ git config commit.template commit_template.txt
	       $ cat >.git/hooks/commit-msg <<EOF
	       > #!/bin/sh
	       > git interpret-trailers --trim-empty --trailer "git-version: \$(git describe)" "\$1" > "\$1.new"
	       > mv "\$1.new" "\$1"
	       > EOF
	       $ chmod +x .git/hooks/commit-msg


SEE ALSO
       git-commit(1), git-format-patch(1), git-config(1)

GIT
       Part of the git(1) suite



Git 2.38.4			  05/16/2024		 GIT-INTERPRET-TRAI(1)