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] [--quiet]

[<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] " followed by

the concatenation of lines from the commit message up to the first blank

line (see the DISCUSSION section of linkgit:git-commit[1]).

When multiple patches are output, the subject prefix will instead be

"[PATCH n/m] ". 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.

The negated form `--no-to` discards all `To:` headers added so

far (from config or command line).

--cc=<email>::

Add a `Cc:` header to the email headers. This is in addition

to any configured headers, and may be used multiple times.

The negated form `--no-cc` discards all `Cc:` headers added so

far (from config or command line).

--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"`.

The negated form `--no-add-header` discards *all* (`To:`,

`Cc:`, and custom) headers added so far from config or command

line.

--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`.

--quiet::

Do not print the names of the generated files to standard output.

--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.

Checking for patch corruption

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Many mailers if not set up properly will corrupt whitespace. Here are

two common types of corruption:

* Empty context lines that do not have _any_ whitespace.

* Non-empty context lines that have one extra whitespace at the

beginning.

One way to test if your MUA is set up correctly is:

* Send the patch to yourself, exactly the way you would, except

with To: and Cc: lines that do not contain the list and

maintainer address.

* Save that patch to a file in UNIX mailbox format. Call it a.patch,

say.

* Apply it:

$ git fetch <project> master:test-apply

$ git checkout test-apply

$ git reset --hard

$ git am a.patch

If it does not apply correctly, there can be various reasons.

* The patch itself does not apply cleanly. That is _bad_ but

does not have much to do with your MUA. You might want to rebase

the patch with linkgit:git-rebase[1] before regenerating it in

this case.

* The MUA corrupted your patch; "am" would complain that

the patch does not apply. Look in the .git/rebase-apply/ subdirectory and

see what 'patch' file contains and check for the common

corruption patterns mentioned above.

* While at it, check the 'info' and 'final-commit' files as well.

If what is in 'final-commit' is not exactly what you would want to

see in the commit log message, it is very likely that the

receiver would end up hand editing the log message when applying

your patch. Things like "Hi, this is my first patch.\n" in the

patch e-mail should come after the three-dash line that signals

the end of the commit message.

MUA-SPECIFIC HINTS

------------------

Here are some hints on how to successfully submit patches inline using

various mailers.

GMail

~~~~~

GMail does not have any way to turn off line wrapping in the web

interface, so it will mangle any emails that you send. You can however

use "git send-email" and send your patches through the GMail SMTP server, or

use any IMAP email client to connect to the google IMAP server and forward

the emails through that.

For hints on using 'git send-email' to send your patches through the

GMail SMTP server, see the EXAMPLE section of linkgit:git-send-email[1].

For hints on submission using the IMAP interface, see the EXAMPLE

section of linkgit:git-imap-send[1].

Thunderbird

~~~~~~~~~~~

By default, Thunderbird will both wrap emails as well as flag

them as being 'format=flowed', both of which will make the

resulting email unusable by git.

There are three different approaches: use an add-on to turn off line wraps,

configure Thunderbird to not mangle patches, or use

an external editor to keep Thunderbird from mangling the patches.

Approach #1 (add-on)

^^^^^^^^^^^^^^^^^^^^

Install the Toggle Word Wrap add-on that is available from

https://addons.mozilla.org/thunderbird/addon/toggle-word-wrap/

It adds a menu entry "Enable Word Wrap" in the composer's "Options" menu

that you can tick off. Now you can compose the message as you otherwise do

(cut + paste, 'git format-patch' | 'git imap-send', etc), but you have to

insert line breaks manually in any text that you type.

Approach #2 (configuration)

^^^^^^^^^^^^^^^^^^^^^^^^^^^

Three steps:

1. Configure your mail server composition as plain text:

Edit...Account Settings...Composition & Addressing,

uncheck "Compose Messages in HTML".

2. Configure your general composition window to not wrap.

+

In Thunderbird 2:

Edit..Preferences..Composition, wrap plain text messages at 0

+

In Thunderbird 3:

Edit..Preferences..Advanced..Config Editor. Search for

"mail.wrap_long_lines".

Toggle it to make sure it is set to `false`.

3. Disable the use of format=flowed:

Edit..Preferences..Advanced..Config Editor. Search for

"mailnews.send_plaintext_flowed".

Toggle it to make sure it is set to `false`.

After that is done, you should be able to compose email as you

otherwise would (cut + paste, 'git format-patch' | 'git imap-send', etc),

and the patches will not be mangled.

Approach #3 (external editor)

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The following Thunderbird extensions are needed:

AboutConfig from http://aboutconfig.mozdev.org/ and

External Editor from http://globs.org/articles.php?lng=en&pg=8

1. Prepare the patch as a text file using your method of choice.

2. Before opening a compose window, use Edit->Account Settings to

uncheck the "Compose messages in HTML format" setting in the

"Composition & Addressing" panel of the account to be used to

send the patch.

3. In the main Thunderbird window, 'before' you open the compose

window for the patch, use Tools->about:config to set the

following to the indicated values:

+

----------

mailnews.send_plaintext_flowed => false

mailnews.wraplength => 0

----------

4. Open a compose window and click the external editor icon.

5. In the external editor window, read in the patch file and exit

the editor normally.

Side note: it may be possible to do step 2 with

about:config and the following settings but no one's tried yet.

----------

mail.html_compose => false

mail.identity.default.compose_html => false

mail.identity.id?.compose_html => false

----------

There is a script in contrib/thunderbird-patch-inline which can help

you include patches with Thunderbird in an easy way. To use it, do the

steps above and then use the script as the external editor.

KMail

~~~~~

This should help you to submit patches inline using KMail.

1. Prepare the patch as a text file.

2. Click on New Mail.

3. Go under "Options" in the Composer window and be sure that

"Word wrap" is not set.

4. Use Message -> Insert file... and insert the patch.

5. Back in the compose window: add whatever other text you wish to the

message, complete the addressing and subject fields, and press send.

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