Add or parse trailer lines that look similar to RFC 822 e-mail
headers, at the end of the otherwise free-form part of a commit
message. For example, in the following commit message
subject
Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Signed-off-by: Alice <alice@example.com>
Signed-off-by: Bob <bob@example.com>
the last two lines starting with "Signed-off-by" are trailers.
This command reads 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
coming from the input, without influencing them with any command line
options or configuration variables.
Otherwise, this command applies trailer.* configuration variables
(which could potentially add new trailers, as well as reposition them),
as well as any command line arguments that can override configuration
variables (such as --trailer=... which could also add new trailers),
to each input file. The result is emitted on the standard output.
This command can also operate on the output of git-format-patch(1),
which is more elaborate than a plain commit message. Namely, such output
includes a commit message (as above), a "---" divider line, and a patch part.
For these inputs, the divider and patch parts are not modified by
this command and are emitted as is on the output, unless
--no-divider is specified.
Some configuration variables control the way the --trailer arguments
are applied to each input and the way any existing trailer in
the input is changed. They also make it possible to
automatically add some trailers.
By default, a <key>=<value> or <key>:<value> argument given
using --trailer will be appended after the existing trailers only if
the last trailer has a different (<key>, <value>) pair (or if there
is no existing trailer). The <key> and <value> parts will be trimmed
to remove starting and trailing whitespace, and the resulting trimmed
<key> and <value> will appear in the output like this:
This means that the trimmed <key> and <value> will be separated by
': ' (one colon followed by one space).
For convenience, a <keyAlias> can be configured to make using --trailer
shorter to type on the command line. This can be configured using the
trailer.<keyAlias>.key configuration variable. The <keyAlias> must be a prefix
of the full <key> string, although case sensitivity does not matter. For
example, if you have
trailer.sign.key "Signed-off-by: "
in your configuration, you only need to specify --trailer="sign: foo"
on the command line instead of --trailer="Signed-off-by: foo".
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
at the end of the input. A blank line will be added before the new
trailer if there isn’t one already.
Existing trailers are extracted from the input 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 input or be the last
non-whitespace lines before a line that starts with --- (followed by a
space or the end of the line).
When reading trailers, there can be no whitespace before or inside the
<key>, but any number of regular space and tab characters are allowed
between the <key> 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. Example:
key: This is a very long value, with spaces and
newlines in it.
Note that trailers do not follow (nor are they intended to follow) many of the
rules for RFC 822 headers. For example they do not follow the encoding rule.