format-patch: inform user that patch-id generation is unstable
[git/git.git] / Documentation / git-format-patch.txt
CommitLineData
215a7ad1
JH
1git-format-patch(1)
2===================
7fc9d69f
JH
3
4NAME
5----
7bd7f280 6git-format-patch - Prepare patches for e-mail submission
7fc9d69f
JH
7
8
9SYNOPSIS
10--------
353ce815 11[verse]
50710ce4 12'git format-patch' [-k] [(-o|--output-directory) <dir> | --stdout]
f693b7e9 13 [--no-thread | --thread[=<style>]]
50710ce4
SB
14 [(--attach|--inline)[=<boundary>] | --no-attach]
15 [-s | --signoff]
6622d9c7 16 [--signature=<signature> | --no-signature]
7022650f 17 [--signature-file=<file>]
a5a27c79
DB
18 [-n | --numbered | -N | --no-numbered]
19 [--start-number <n>] [--numbered-files]
20 [--in-reply-to=Message-Id] [--suffix=.<sfx>]
21 [--ignore-if-in-upstream]
68e83a5b
JT
22 [--rfc] [--subject-prefix=Subject-Prefix]
23 [(--reroll-count|-v) <n>]
ae6c098f 24 [--to=<email>] [--cc=<email>]
2a4c2607 25 [--[no-]cover-letter] [--quiet] [--notes[=<ref>]]
126facf8 26 [--interdiff=<previous>]
8631bf1c 27 [--range-diff=<previous> [--creation-factor=<percent>]]
738e88a2 28 [--progress]
50710ce4 29 [<common diff options>]
8a1d076e 30 [ <since> | <revision range> ]
7fc9d69f
JH
31
32DESCRIPTION
33-----------
2052d146 34
8a1d076e 35Prepare each commit with its patch in
2052d146 36one file per commit, formatted to resemble UNIX mailbox format.
2052d146 37The output of this command is convenient for e-mail submission or
0b444cdb 38for use with 'git am'.
35ef3a4c 39
8a1d076e
JH
40There are two ways to specify which commits to operate on.
41
421. A single commit, <since>, specifies that the commits leading
43 to the tip of the current branch that are not in the history
44 that leads to the <since> to be output.
45
462. Generic <revision range> expression (see "SPECIFYING
9d83e382 47 REVISIONS" section in linkgit:gitrevisions[7]) means the
2f6a3823
JH
48 commits in the specified range.
49
2d266f9d
TR
50The first rule takes precedence in the case of a single <commit>. To
51apply the second rule, i.e., format everything since the beginning of
9e9f132f 52history up until <commit>, use the `--root` option: `git format-patch
6cf378f0 53--root <commit>`. If you want to format only <commit> itself, you
dce5ef14 54can do this with `git format-patch -1 <commit>`.
8a1d076e 55
e6ff0f42 56By default, each output file is numbered sequentially from 1, and uses the
2052d146 57first line of the commit message (massaged for pathname safety) as
dce5ef14 58the filename. With the `--numbered-files` option, the output file names
e6ff0f42
JL
59will only be numbers, without the first line of the commit appended.
60The names of the output files are printed to standard
dce5ef14 61output, unless the `--stdout` option is specified.
66f04f38 62
dce5ef14 63If `-o` is specified, output files are created in <dir>. Otherwise
bc6bf2d7 64they are created in the current working directory. The default path
ae9f6311 65can be set with the `format.outputDirectory` configuration option.
bc6bf2d7
AK
66The `-o` option takes precedence over `format.outputDirectory`.
67To store patches in the current working directory even when
68`format.outputDirectory` points elsewhere, use `-o .`.
35ef3a4c 69
52ffe995
JW
70By default, the subject of a single patch is "[PATCH] " followed by
71the concatenation of lines from the commit message up to the first blank
72line (see the DISCUSSION section of linkgit:git-commit[1]).
73
74When multiple patches are output, the subject prefix will instead be
75"[PATCH n/m] ". To force 1/1 to be added for a single patch, use `-n`.
76To omit patch numbers from the subject, use `-N`.
35ef3a4c 77
dce5ef14
BG
78If given `--thread`, `git-format-patch` will generate `In-Reply-To` and
79`References` headers to make the second and subsequent patch mails appear
80as replies to the first mail; this also generates a `Message-Id` header to
cc35de84 81reference.
7fc9d69f
JH
82
83OPTIONS
84-------
c1a95fa6 85:git-format-patch: 1
b8105375
BG
86include::diff-options.txt[]
87
ed5f07a6 88-<n>::
2c642ed8 89 Prepare patches from the topmost <n> commits.
ed5f07a6 90
3240240f
SB
91-o <dir>::
92--output-directory <dir>::
35ef3a4c 93 Use <dir> to store the resulting files, instead of the
efd02016 94 current working directory.
35ef3a4c 95
3240240f
SB
96-n::
97--numbered::
a567fdcb 98 Name output in '[PATCH n/m]' format, even with a single patch.
35ef3a4c 99
3240240f
SB
100-N::
101--no-numbered::
49604a4d
BG
102 Name output in '[PATCH]' format.
103
2052d146
DS
104--start-number <n>::
105 Start numbering the patches at <n> instead of 1.
106
e6ff0f42
JL
107--numbered-files::
108 Output file names will be a simple number sequence
109 without the default first line of the commit appended.
e6ff0f42 110
3240240f
SB
111-k::
112--keep-subject::
35ef3a4c
JH
113 Do not strip/add '[PATCH]' from the first line of the
114 commit log message.
115
3240240f
SB
116-s::
117--signoff::
6f855371
NW
118 Add `Signed-off-by:` line to the commit message, using
119 the committer identity of yourself.
b2c150d3 120 See the signoff option in linkgit:git-commit[1] for more information.
6f855371 121
54ba6013 122--stdout::
2052d146
DS
123 Print all commits to the standard output in mbox format,
124 instead of creating a file for each one.
7fc9d69f 125
c112f689
JS
126--attach[=<boundary>]::
127 Create multipart/mixed attachment, the first part of
128 which is the commit message and the patch itself in the
dce5ef14 129 second part, with `Content-Disposition: attachment`.
c112f689 130
0db5260b
JW
131--no-attach::
132 Disable the creation of an attachment, overriding the
133 configuration setting.
134
c112f689
JS
135--inline[=<boundary>]::
136 Create multipart/mixed attachment, the first part of
137 which is the commit message and the patch itself in the
dce5ef14 138 second part, with `Content-Disposition: inline`.
a15a44ef 139
30984ed2 140--thread[=<style>]::
f693b7e9 141--no-thread::
dce5ef14 142 Controls addition of `In-Reply-To` and `References` headers to
f693b7e9 143 make the second and subsequent mails appear as replies to the
dce5ef14 144 first. Also controls generation of the `Message-Id` header to
f693b7e9 145 reference.
30984ed2
TR
146+
147The optional <style> argument can be either `shallow` or `deep`.
fd1ff306 148'shallow' threading makes every mail a reply to the head of the
30984ed2 149series, where the head is chosen from the cover letter, the
6cf378f0 150`--in-reply-to`, and the first patch mail, in this order. 'deep'
f693b7e9
YD
151threading makes every mail a reply to the previous one.
152+
ae9f6311 153The default is `--no-thread`, unless the `format.thread` configuration
dce5ef14 154is set. If `--thread` is specified without a style, it defaults to the
ae9f6311 155style specified by `format.thread` if any, or else `shallow`.
f693b7e9
YD
156+
157Beware that the default for 'git send-email' is to thread emails
dce5ef14
BG
158itself. If you want `git format-patch` to take care of threading, you
159will want to ensure that threading is disabled for `git send-email`.
28ffb898 160
da56645d 161--in-reply-to=Message-Id::
dce5ef14 162 Make the first mail (or all the mails with `--no-thread`) appear as a
da56645d
JT
163 reply to the given Message-Id, which avoids breaking threads to
164 provide a new patch series.
165
cc75ad67
DK
166--ignore-if-in-upstream::
167 Do not include a patch that matches a commit in
168 <until>..<since>. This will examine all patches reachable
169 from <since> but not from <until> and compare them with the
170 patches being generated, and any patch that matches is
171 ignored.
172
2d9e4a47
RJ
173--subject-prefix=<Subject-Prefix>::
174 Instead of the standard '[PATCH]' prefix in the subject
175 line, instead use '[<Subject-Prefix>]'. This
176 allows for useful naming of a patch series, and can be
dce5ef14 177 combined with the `--numbered` option.
2d9e4a47 178
68e83a5b
JT
179--rfc::
180 Alias for `--subject-prefix="RFC PATCH"`. RFC means "Request For
181 Comments"; use this when sending an experimental patch for
182 discussion rather than application.
183
7952ea66 184-v <n>::
4aad08e0
JH
185--reroll-count=<n>::
186 Mark the series as the <n>-th iteration of the topic. The
d614f075 187 output filenames have `v<n>` prepended to them, and the
4aad08e0
JH
188 subject prefix ("PATCH" by default, but configurable via the
189 `--subject-prefix` option) has ` v<n>` appended to it. E.g.
190 `--reroll-count=4` may produce `v4-0001-add-makefile.patch`
191 file that has "Subject: [PATCH v4 1/20] Add makefile" in it.
192
ae6c098f
SD
193--to=<email>::
194 Add a `To:` header to the email headers. This is in addition
195 to any configured headers, and may be used multiple times.
b2cd17b9
TR
196 The negated form `--no-to` discards all `To:` headers added so
197 far (from config or command line).
ae6c098f 198
736cc67d 199--cc=<email>::
dce5ef14 200 Add a `Cc:` header to the email headers. This is in addition
736cc67d 201 to any configured headers, and may be used multiple times.
b2cd17b9
TR
202 The negated form `--no-cc` discards all `Cc:` headers added so
203 far (from config or command line).
736cc67d 204
a9080475
JK
205--from::
206--from=<ident>::
207 Use `ident` in the `From:` header of each commit email. If the
208 author ident of the commit is not textually identical to the
209 provided `ident`, place a `From:` header in the body of the
210 message with the original author. If no `ident` is given, use
211 the committer ident.
212+
213Note that this option is only useful if you are actually sending the
214emails and want to identify yourself as the sender, but retain the
215original author (and `git am` will correctly pick up the in-body
216header). Note also that `git send-email` already handles this
217transformation for you, and this option should not be used if you are
218feeding the result to `git send-email`.
219
d7d9c2d0
MH
220--add-header=<header>::
221 Add an arbitrary header to the email headers. This is in addition
222 to any configured headers, and may be used multiple times.
b2cd17b9
TR
223 For example, `--add-header="Organization: git-foo"`.
224 The negated form `--no-add-header` discards *all* (`To:`,
225 `Cc:`, and custom) headers added so far from config or command
226 line.
d7d9c2d0 227
2a4c2607 228--[no-]cover-letter::
f4912391 229 In addition to the patches, generate a cover letter file
561d2b79 230 containing the branch description, shortlog and the overall diffstat. You can
f4912391 231 fill in a description in the file before sending it out.
a5a27c79 232
126facf8 233--interdiff=<previous>::
ee6cbf71
ES
234 As a reviewer aid, insert an interdiff into the cover letter,
235 or as commentary of the lone patch of a 1-patch series, showing
126facf8
ES
236 the differences between the previous version of the patch series and
237 the series currently being formatted. `previous` is a single revision
238 naming the tip of the previous series which shares a common base with
239 the series being formatted (for example `git format-patch
240 --cover-letter --interdiff=feature/v1 -3 feature/v2`).
241
31e2617a
ES
242--range-diff=<previous>::
243 As a reviewer aid, insert a range-diff (see linkgit:git-range-diff[1])
40ce4160
ES
244 into the cover letter, or as commentary of the lone patch of a
245 1-patch series, showing the differences between the previous
31e2617a 246 version of the patch series and the series currently being formatted.
2e6fd71a
ES
247 `previous` can be a single revision naming the tip of the previous
248 series if it shares a common base with the series being formatted (for
31e2617a 249 example `git format-patch --cover-letter --range-diff=feature/v1 -3
2e6fd71a
ES
250 feature/v2`), or a revision range if the two versions of the series are
251 disjoint (for example `git format-patch --cover-letter
252 --range-diff=feature/v1~3..feature/v1 -3 feature/v2`).
d8981c3f
JH
253+
254Note that diff options passed to the command affect how the primary
255product of `format-patch` is generated, and they are not passed to
256the underlying `range-diff` machinery used to generate the cover-letter
257material (this may change in the future).
31e2617a 258
8631bf1c
ES
259--creation-factor=<percent>::
260 Used with `--range-diff`, tweak the heuristic which matches up commits
261 between the previous and current series of patches by adjusting the
262 creation/deletion cost fudge factor. See linkgit:git-range-diff[1])
263 for details.
264
e422c0cf
JH
265--notes[=<ref>]::
266 Append the notes (see linkgit:git-notes[1]) for the commit
267 after the three-dash line.
268+
269The expected use case of this is to write supporting explanation for
6454d9f1
PO
270the commit that does not belong to the commit log message proper,
271and include it with the patch submission. While one can simply write
272these explanations after `format-patch` has run but before sending,
2de9b711 273keeping them as Git notes allows them to be maintained between versions
6454d9f1
PO
274of the patch series (but see the discussion of the `notes.rewrite`
275configuration options in linkgit:git-notes[1] to use this workflow).
e422c0cf 276
2c7ee986 277--[no-]signature=<signature>::
6622d9c7
SB
278 Add a signature to each message produced. Per RFC 3676 the signature
279 is separated from the body by a line with '-- ' on it. If the
2de9b711 280 signature option is omitted the signature defaults to the Git version
6622d9c7
SB
281 number.
282
7022650f
JM
283--signature-file=<file>::
284 Works just like --signature except the signature is read from a file.
285
03eeaeae 286--suffix=.<sfx>::
917a8f89 287 Instead of using `.patch` as the suffix for generated
02783075 288 filenames, use specified suffix. A common alternative is
50710ce4
SB
289 `--suffix=.txt`. Leaving this empty will remove the `.patch`
290 suffix.
03eeaeae 291+
50710ce4
SB
292Note that the leading character does not have to be a dot; for example,
293you can use `--suffix=-patch` to get `0001-description-of-my-change-patch`.
03eeaeae 294
b7df098c 295-q::
b781cfaf
CMN
296--quiet::
297 Do not print the names of the generated files to standard output.
298
37c22a4b 299--no-binary::
50710ce4
SB
300 Do not output contents of changes in binary files, instead
301 display a notice that those files changed. Patches generated
302 using this option cannot be applied properly, but they are
303 still useful for code review.
37c22a4b 304
3a30aa17 305--zero-commit::
306 Output an all-zero hash in each patch's From header instead
307 of the hash of the commit.
308
fa2ab86d
XY
309--base=<commit>::
310 Record the base tree information to identify the state the
311 patch series applies to. See the BASE TREE INFORMATION section
312 below for details.
313
2d266f9d
TR
314--root::
315 Treat the revision argument as a <revision range>, even if it
316 is just a single commit (that would normally be treated as a
317 <since>). Note that root commits included in the specified
318 range are always formatted as creation patches, independently
319 of this flag.
320
738e88a2
KW
321--progress::
322 Show progress reports on stderr as patches are generated.
323
96ce6d26
MM
324CONFIGURATION
325-------------
50710ce4
SB
326You can specify extra mail header lines to be added to each message,
327defaults for the subject prefix and file suffix, number patches when
ae6c098f
SD
328outputting more than one patch, add "To" or "Cc:" headers, configure
329attachments, and sign off patches with configuration variables.
96ce6d26 330
917a8f89 331------------
96ce6d26 332[format]
7f9d77f2 333 headers = "Organization: git-foo\n"
da0005b8 334 subjectPrefix = CHANGE
7f9d77f2
JN
335 suffix = .txt
336 numbered = auto
ae6c098f 337 to = <email>
fe8928e6 338 cc = <email>
0db5260b 339 attach [ = mime-boundary-string ]
da0005b8 340 signOff = true
2a4c2607 341 coverletter = auto
917a8f89 342------------
03eeaeae 343
96ce6d26 344
e0d48279
JN
345DISCUSSION
346----------
347
348The patch produced by 'git format-patch' is in UNIX mailbox format,
349with a fixed "magic" time stamp to indicate that the file is output
350from format-patch rather than a real mailbox, like so:
351
352------------
353From 8f72bad1baf19a53459661343e21d6491c3908d3 Mon Sep 17 00:00:00 2001
354From: Tony Luck <tony.luck@intel.com>
355Date: Tue, 13 Jul 2010 11:42:54 -0700
356Subject: [PATCH] =?UTF-8?q?[IA64]=20Put=20ia64=20config=20files=20on=20the=20?=
357 =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig=20diet?=
358MIME-Version: 1.0
359Content-Type: text/plain; charset=UTF-8
360Content-Transfer-Encoding: 8bit
361
362arch/arm config files were slimmed down using a python script
363(See commit c2330e286f68f1c408b4aa6515ba49d57f05beae comment)
364
365Do the same for ia64 so we can have sleek & trim looking
366...
367------------
368
369Typically it will be placed in a MUA's drafts folder, edited to add
370timely commentary that should not go in the changelog after the three
371dashes, and then sent as a message whose body, in our example, starts
372with "arch/arm config files were...". On the receiving end, readers
373can save interesting patches in a UNIX mailbox and apply them with
374linkgit:git-am[1].
375
376When a patch is part of an ongoing discussion, the patch generated by
377'git format-patch' can be tweaked to take advantage of the 'git am
378--scissors' feature. After your response to the discussion comes a
379line that consists solely of "`-- >8 --`" (scissors and perforation),
380followed by the patch with unnecessary header fields removed:
381
382------------
383...
384> So we should do such-and-such.
385
386Makes sense to me. How about this patch?
387
388-- >8 --
389Subject: [IA64] Put ia64 config files on the Uwe Kleine-König diet
390
391arch/arm config files were slimmed down using a python script
392...
393------------
394
395When sending a patch this way, most often you are sending your own
396patch, so in addition to the "`From $SHA1 $magic_timestamp`" marker you
397should omit `From:` and `Date:` lines from the patch file. The patch
398title is likely to be different from the subject of the discussion the
399patch is in response to, so it is likely that you would want to keep
400the Subject: line, like the example above.
401
57756161
JN
402Checking for patch corruption
403~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
404Many mailers if not set up properly will corrupt whitespace. Here are
405two common types of corruption:
406
407* Empty context lines that do not have _any_ whitespace.
408
409* Non-empty context lines that have one extra whitespace at the
410 beginning.
411
412One way to test if your MUA is set up correctly is:
413
414* Send the patch to yourself, exactly the way you would, except
415 with To: and Cc: lines that do not contain the list and
416 maintainer address.
417
418* Save that patch to a file in UNIX mailbox format. Call it a.patch,
419 say.
420
421* Apply it:
422
423 $ git fetch <project> master:test-apply
424 $ git checkout test-apply
425 $ git reset --hard
426 $ git am a.patch
427
428If it does not apply correctly, there can be various reasons.
429
430* The patch itself does not apply cleanly. That is _bad_ but
431 does not have much to do with your MUA. You might want to rebase
432 the patch with linkgit:git-rebase[1] before regenerating it in
433 this case.
434
435* The MUA corrupted your patch; "am" would complain that
436 the patch does not apply. Look in the .git/rebase-apply/ subdirectory and
437 see what 'patch' file contains and check for the common
438 corruption patterns mentioned above.
439
440* While at it, check the 'info' and 'final-commit' files as well.
441 If what is in 'final-commit' is not exactly what you would want to
442 see in the commit log message, it is very likely that the
443 receiver would end up hand editing the log message when applying
444 your patch. Things like "Hi, this is my first patch.\n" in the
445 patch e-mail should come after the three-dash line that signals
446 the end of the commit message.
447
dc53151f
JN
448MUA-SPECIFIC HINTS
449------------------
450Here are some hints on how to successfully submit patches inline using
451various mailers.
452
36c10e6d
JN
453GMail
454~~~~~
455GMail does not have any way to turn off line wrapping in the web
456interface, so it will mangle any emails that you send. You can however
457use "git send-email" and send your patches through the GMail SMTP server, or
458use any IMAP email client to connect to the google IMAP server and forward
459the emails through that.
460
461For hints on using 'git send-email' to send your patches through the
462GMail SMTP server, see the EXAMPLE section of linkgit:git-send-email[1].
463
464For hints on submission using the IMAP interface, see the EXAMPLE
465section of linkgit:git-imap-send[1].
466
dc53151f
JN
467Thunderbird
468~~~~~~~~~~~
469By default, Thunderbird will both wrap emails as well as flag
470them as being 'format=flowed', both of which will make the
2de9b711 471resulting email unusable by Git.
dc53151f 472
b8959605
JS
473There are three different approaches: use an add-on to turn off line wraps,
474configure Thunderbird to not mangle patches, or use
dc53151f
JN
475an external editor to keep Thunderbird from mangling the patches.
476
b8959605
JS
477Approach #1 (add-on)
478^^^^^^^^^^^^^^^^^^^^
479
480Install the Toggle Word Wrap add-on that is available from
481https://addons.mozilla.org/thunderbird/addon/toggle-word-wrap/
482It adds a menu entry "Enable Word Wrap" in the composer's "Options" menu
483that you can tick off. Now you can compose the message as you otherwise do
484(cut + paste, 'git format-patch' | 'git imap-send', etc), but you have to
485insert line breaks manually in any text that you type.
486
487Approach #2 (configuration)
dc53151f
JN
488^^^^^^^^^^^^^^^^^^^^^^^^^^^
489Three steps:
490
4911. Configure your mail server composition as plain text:
492 Edit...Account Settings...Composition & Addressing,
493 uncheck "Compose Messages in HTML".
494
4952. Configure your general composition window to not wrap.
496+
497In Thunderbird 2:
498Edit..Preferences..Composition, wrap plain text messages at 0
499+
500In Thunderbird 3:
501Edit..Preferences..Advanced..Config Editor. Search for
502"mail.wrap_long_lines".
f737684d
RJ
503Toggle it to make sure it is set to `false`. Also, search for
504"mailnews.wraplength" and set the value to 0.
dc53151f
JN
505
5063. Disable the use of format=flowed:
ba170517
JNA
507 Edit..Preferences..Advanced..Config Editor. Search for
508 "mailnews.send_plaintext_flowed".
509 Toggle it to make sure it is set to `false`.
dc53151f
JN
510
511After that is done, you should be able to compose email as you
512otherwise would (cut + paste, 'git format-patch' | 'git imap-send', etc),
513and the patches will not be mangled.
514
b8959605 515Approach #3 (external editor)
dc53151f
JN
516^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
517
518The following Thunderbird extensions are needed:
519AboutConfig from http://aboutconfig.mozdev.org/ and
520External Editor from http://globs.org/articles.php?lng=en&pg=8
521
5221. Prepare the patch as a text file using your method of choice.
523
5242. Before opening a compose window, use Edit->Account Settings to
525 uncheck the "Compose messages in HTML format" setting in the
526 "Composition & Addressing" panel of the account to be used to
527 send the patch.
528
5293. In the main Thunderbird window, 'before' you open the compose
530 window for the patch, use Tools->about:config to set the
531 following to the indicated values:
532+
533----------
534 mailnews.send_plaintext_flowed => false
535 mailnews.wraplength => 0
536----------
537
5384. Open a compose window and click the external editor icon.
539
5405. In the external editor window, read in the patch file and exit
541 the editor normally.
542
543Side note: it may be possible to do step 2 with
544about:config and the following settings but no one's tried yet.
545
546----------
547 mail.html_compose => false
548 mail.identity.default.compose_html => false
549 mail.identity.id?.compose_html => false
550----------
551
552There is a script in contrib/thunderbird-patch-inline which can help
553you include patches with Thunderbird in an easy way. To use it, do the
554steps above and then use the script as the external editor.
555
967ab8ef
JN
556KMail
557~~~~~
558This should help you to submit patches inline using KMail.
559
5601. Prepare the patch as a text file.
561
5622. Click on New Mail.
563
5643. Go under "Options" in the Composer window and be sure that
565 "Word wrap" is not set.
566
5674. Use Message -> Insert file... and insert the patch.
568
5695. Back in the compose window: add whatever other text you wish to the
570 message, complete the addressing and subject fields, and press send.
571
fa2ab86d
XY
572BASE TREE INFORMATION
573---------------------
574
575The base tree information block is used for maintainers or third party
576testers to know the exact state the patch series applies to. It consists
577of the 'base commit', which is a well-known commit that is part of the
578stable part of the project history everybody else works off of, and zero
579or more 'prerequisite patches', which are well-known patches in flight
580that is not yet part of the 'base commit' that need to be applied on top
581of 'base commit' in topological order before the patches can be applied.
582
583The 'base commit' is shown as "base-commit: " followed by the 40-hex of
584the commit object name. A 'prerequisite patch' is shown as
585"prerequisite-patch-id: " followed by the 40-hex 'patch id', which can
6f93d261 586be obtained by passing the patch through the `git patch-id --unstable`
fa2ab86d
XY
587command.
588
589Imagine that on top of the public commit P, you applied well-known
590patches X, Y and Z from somebody else, and then built your three-patch
591series A, B, C, the history would be like:
592
593................................................
594---P---X---Y---Z---A---B---C
595................................................
596
597With `git format-patch --base=P -3 C` (or variants thereof, e.g. with
7ba1ceef 598`--cover-letter` or using `Z..C` instead of `-3 C` to specify the
fa2ab86d
XY
599range), the base tree information block is shown at the end of the
600first message the command outputs (either the first patch, or the
601cover letter), like this:
602
603------------
604base-commit: P
605prerequisite-patch-id: X
606prerequisite-patch-id: Y
607prerequisite-patch-id: Z
608------------
609
610For non-linear topology, such as
611
612................................................
613---P---X---A---M---C
614 \ /
615 Y---Z---B
616................................................
617
618You can also use `git format-patch --base=P -3 C` to generate patches
619for A, B and C, and the identifiers for P, X, Y, Z are appended at the
620end of the first message.
e0d48279 621
3de66517
XY
622If set `--base=auto` in cmdline, it will track base commit automatically,
623the base commit will be the merge base of tip commit of the remote-tracking
624branch and revision-range specified in cmdline.
625For a local branch, you need to track a remote branch by `git branch
626--set-upstream-to` before using this option.
627
28ffb898
JH
628EXAMPLES
629--------
630
921177f5 631* Extract commits between revisions R1 and R2, and apply them on top of
ba170517 632 the current branch using 'git am' to cherry-pick them:
921177f5
CC
633+
634------------
467c0197 635$ git format-patch -k --stdout R1..R2 | git am -3 -k
921177f5
CC
636------------
637
638* Extract all commits which are in the current branch but not in the
ba170517 639 origin branch:
921177f5
CC
640+
641------------
642$ git format-patch origin
643------------
644+
645For each commit a separate file is created in the current directory.
646
647* Extract all commits that lead to 'origin' since the inception of the
ba170517 648 project:
921177f5
CC
649+
650------------
9c67c757 651$ git format-patch --root origin
921177f5
CC
652------------
653
654* The same as the previous one:
655+
656------------
657$ git format-patch -M -B origin
658------------
659+
660Additionally, it detects and handles renames and complete rewrites
661intelligently to produce a renaming patch. A renaming patch reduces
50710ce4 662the amount of text output, and generally makes it easier to review.
2de9b711
TA
663Note that non-Git "patch" programs won't understand renaming patches, so
664use it only when you know the recipient uses Git to apply your patch.
921177f5
CC
665
666* Extract three topmost commits from the current branch and format them
ba170517 667 as e-mailable patches:
921177f5
CC
668+
669------------
670$ git format-patch -3
671------------
28ffb898 672
56ae8df5 673SEE ALSO
28ffb898 674--------
5162e697 675linkgit:git-am[1], linkgit:git-send-email[1]
28ffb898 676
7fc9d69f
JH
677GIT
678---
9e1f0a85 679Part of the linkgit:git[1] suite