path: root/Documentation/git-format-patch.txt

git-format-patch(1)
===================

NAME
----
git-format-patch - Prepare patches for e-mail submission


SYNOPSIS
--------
[verse]
'git format-patch' [-k] [(-o|--output-directory) <dir> | --stdout]
		   [--no-thread | --thread[=<style>]]
		   [(--attach|--inline)[=<boundary>] | --no-attach]
		   [-s | --signoff]
		   [--signature=<signature> | --no-signature]
		   [-n | --numbered | -N | --no-numbered]
		   [--start-number <n>] [--numbered-files]
		   [--in-reply-to=Message-Id] [--suffix=.<sfx>]
		   [--ignore-if-in-upstream]
		   [--subject-prefix=Subject-Prefix]
		   [--to=<email>] [--cc=<email>]
		   [--cover-letter]
		   [<common diff options>]
		   [ <since> | <revision range> ]

DESCRIPTION
-----------

Prepare each commit with its patch in
one file per commit, formatted to resemble UNIX mailbox format.
The output of this command is convenient for e-mail submission or
for use with 'git am'.

There are two ways to specify which commits to operate on.

1. A single commit, <since>, specifies that the commits leading
   to the tip of the current branch that are not in the history
   that leads to the <since> to be output.

2. Generic <revision range> expression (see "SPECIFYING
   REVISIONS" section in linkgit:gitrevisions[7]) means the
   commits in the specified range.

The first rule takes precedence in the case of a single <commit>.  To
apply the second rule, i.e., format everything since the beginning of
history up until <commit>, use the '\--root' option: `git format-patch
\--root <commit>`.  If you want to format only <commit> itself, you
can do this with `git format-patch -1 <commit>`.

By default, each output file is numbered sequentially from 1, and uses the
first line of the commit message (massaged for pathname safety) as
the filename. With the `--numbered-files` option, the output file names
will only be numbers, without the first line of the commit appended.
The names of the output files are printed to standard
output, unless the `--stdout` option is specified.

If `-o` is specified, output files are created in <dir>.  Otherwise
they are created in the current working directory.

By default, the subject of a single patch is "[PATCH] First Line" and
the subject when multiple patches are output is "[PATCH n/m] First
Line". To force 1/1 to be added for a single patch, use `-n`.  To omit
patch numbers from the subject, use `-N`.

If given `--thread`, `git-format-patch` will generate `In-Reply-To` and
`References` headers to make the second and subsequent patch mails appear
as replies to the first mail; this also generates a `Message-Id` header to
reference.

OPTIONS
-------
:git-format-patch: 1
include::diff-options.txt[]

-<n>::
	Prepare patches from the topmost <n> commits.

-o <dir>::
--output-directory <dir>::
	Use <dir> to store the resulting files, instead of the
	current working directory.

-n::
--numbered::
	Name output in '[PATCH n/m]' format, even with a single patch.

-N::
--no-numbered::
	Name output in '[PATCH]' format.

--start-number <n>::
	Start numbering the patches at <n> instead of 1.

--numbered-files::
	Output file names will be a simple number sequence
	without the default first line of the commit appended.

-k::
--keep-subject::
	Do not strip/add '[PATCH]' from the first line of the
	commit log message.

-s::
--signoff::
	Add `Signed-off-by:` line to the commit message, using
	the committer identity of yourself.

--stdout::
	Print all commits to the standard output in mbox format,
	instead of creating a file for each one.

--attach[=<boundary>]::
	Create multipart/mixed attachment, the first part of
	which is the commit message and the patch itself in the
	second part, with `Content-Disposition: attachment`.

--no-attach::
	Disable the creation of an attachment, overriding the
	configuration setting.

--inline[=<boundary>]::
	Create multipart/mixed attachment, the first part of
	which is the commit message and the patch itself in the
	second part, with `Content-Disposition: inline`.

--thread[=<style>]::
--no-thread::
	Controls addition of `In-Reply-To` and `References` headers to
	make the second and subsequent mails appear as replies to the
	first.  Also controls generation of the `Message-Id` header to
	reference.
+
The optional <style> argument can be either `shallow` or `deep`.
'shallow' threading makes every mail a reply to the head of the
series, where the head is chosen from the cover letter, the
`\--in-reply-to`, and the first patch mail, in this order.  'deep'
threading makes every mail a reply to the previous one.
+
The default is `--no-thread`, unless the 'format.thread' configuration
is set.  If `--thread` is specified without a style, it defaults to the
style specified by 'format.thread' if any, or else `shallow`.
+
Beware that the default for 'git send-email' is to thread emails
itself.  If you want `git format-patch` to take care of threading, you
will want to ensure that threading is disabled for `git send-email`.

--in-reply-to=Message-Id::
	Make the first mail (or all the mails with `--no-thread`) appear as a
	reply to the given Message-Id, which avoids breaking threads to
	provide a new patch series.

--ignore-if-in-upstream::
	Do not include a patch that matches a commit in
	<until>..<since>.  This will examine all patches reachable
	from <since> but not from <until> and compare them with the
	patches being generated, and any patch that matches is
	ignored.

--subject-prefix=<Subject-Prefix>::
	Instead of the standard '[PATCH]' prefix in the subject
	line, instead use '[<Subject-Prefix>]'. This
	allows for useful naming of a patch series, and can be
	combined with the `--numbered` option.

--to=<email>::
	Add a `To:` header to the email headers. This is in addition
	to any configured headers, and may be used multiple times.

--cc=<email>::
	Add a `Cc:` header to the email headers. This is in addition
	to any configured headers, and may be used multiple times.

--add-header=<header>::
	Add an arbitrary header to the email headers.  This is in addition
	to any configured headers, and may be used multiple times.
	For example, `--add-header="Organization: git-foo"`

--cover-letter::
	In addition to the patches, generate a cover letter file
	containing the shortlog and the overall diffstat.  You can
	fill in a description in the file before sending it out.

--[no]-signature=<signature>::
	Add a signature to each message produced. Per RFC 3676 the signature
	is separated from the body by a line with '-- ' on it. If the
	signature option is omitted the signature defaults to the git version
	number.

--suffix=.<sfx>::
	Instead of using `.patch` as the suffix for generated
	filenames, use specified suffix.  A common alternative is
	`--suffix=.txt`.  Leaving this empty will remove the `.patch`
	suffix.
+
Note that the leading character does not have to be a dot; for example,
you can use `--suffix=-patch` to get `0001-description-of-my-change-patch`.

--no-binary::
	Do not output contents of changes in binary files, instead
	display a notice that those files changed.  Patches generated
	using this option cannot be applied properly, but they are
	still useful for code review.

--root::
	Treat the revision argument as a <revision range>, even if it
	is just a single commit (that would normally be treated as a
	<since>).  Note that root commits included in the specified
	range are always formatted as creation patches, independently
	of this flag.

CONFIGURATION
-------------
You can specify extra mail header lines to be added to each message,
defaults for the subject prefix and file suffix, number patches when
outputting more than one patch, add "To" or "Cc:" headers, configure
attachments, and sign off patches with configuration variables.

------------
[format]
	headers = "Organization: git-foo\n"
	subjectprefix = CHANGE
	suffix = .txt
	numbered = auto
	to = <email>
	cc = <email>
	attach [ = mime-boundary-string ]
	signoff = true
------------


DISCUSSION
----------

The patch produced by 'git format-patch' is in UNIX mailbox format,
with a fixed "magic" time stamp to indicate that the file is output
from format-patch rather than a real mailbox, like so:

------------
From 8f72bad1baf19a53459661343e21d6491c3908d3 Mon Sep 17 00:00:00 2001
From: Tony Luck <tony.luck@intel.com>
Date: Tue, 13 Jul 2010 11:42:54 -0700
Subject: [PATCH] =?UTF-8?q?[IA64]=20Put=20ia64=20config=20files=20on=20the=20?=
 =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig=20diet?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

arch/arm config files were slimmed down using a python script
(See commit c2330e286f68f1c408b4aa6515ba49d57f05beae comment)

Do the same for ia64 so we can have sleek & trim looking
...
------------

Typically it will be placed in a MUA's drafts folder, edited to add
timely commentary that should not go in the changelog after the three
dashes, and then sent as a message whose body, in our example, starts
with "arch/arm config files were...".  On the receiving end, readers
can save interesting patches in a UNIX mailbox and apply them with
linkgit:git-am[1].

When a patch is part of an ongoing discussion, the patch generated by
'git format-patch' can be tweaked to take advantage of the 'git am
--scissors' feature.  After your response to the discussion comes a
line that consists solely of "`-- >8 --`" (scissors and perforation),
followed by the patch with unnecessary header fields removed:

------------
...
> So we should do such-and-such.

Makes sense to me.  How about this patch?

-- >8 --
Subject: [IA64] Put ia64 config files on the Uwe Kleine-König diet

arch/arm config files were slimmed down using a python script
...
------------

When sending a patch this way, most often you are sending your own
patch, so in addition to the "`From $SHA1 $magic_timestamp`" marker you
should omit `From:` and `Date:` lines from the patch file.  The patch
title is likely to be different from the subject of the discussion the
patch is in response to, so it is likely that you would want to keep
the Subject: line, like the example above.


EXAMPLES
--------

* Extract commits between revisions R1 and R2, and apply them on top of
the current branch using 'git am' to cherry-pick them:
+
------------
$ git format-patch -k --stdout R1..R2 | git am -3 -k
------------

* Extract all commits which are in the current branch but not in the
origin branch:
+
------------
$ git format-patch origin
------------
+
For each commit a separate file is created in the current directory.

* Extract all commits that lead to 'origin' since the inception of the
project:
+
------------
$ git format-patch --root origin
------------

* The same as the previous one:
+
------------
$ git format-patch -M -B origin
------------
+
Additionally, it detects and handles renames and complete rewrites
intelligently to produce a renaming patch.  A renaming patch reduces
the amount of text output, and generally makes it easier to review.
Note that non-git "patch" programs won't understand renaming patches, so
use it only when you know the recipient uses git to apply your patch.

* Extract three topmost commits from the current branch and format them
as e-mailable patches:
+
------------
$ git format-patch -3
------------

SEE ALSO
--------
linkgit:git-am[1], linkgit:git-send-email[1]

GIT
---
Part of the linkgit:git[1] suite