Documentation: explain how to check for patch corruption
[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]
a5a27c79
DB
17 [-n | --numbered | -N | --no-numbered]
18 [--start-number <n>] [--numbered-files]
19 [--in-reply-to=Message-Id] [--suffix=.<sfx>]
20 [--ignore-if-in-upstream]
21 [--subject-prefix=Subject-Prefix]
ae6c098f 22 [--to=<email>] [--cc=<email>]
a5a27c79 23 [--cover-letter]
50710ce4 24 [<common diff options>]
8a1d076e 25 [ <since> | <revision range> ]
7fc9d69f
JH
26
27DESCRIPTION
28-----------
2052d146 29
8a1d076e 30Prepare each commit with its patch in
2052d146 31one file per commit, formatted to resemble UNIX mailbox format.
2052d146 32The output of this command is convenient for e-mail submission or
0b444cdb 33for use with 'git am'.
35ef3a4c 34
8a1d076e
JH
35There are two ways to specify which commits to operate on.
36
371. A single commit, <since>, specifies that the commits leading
38 to the tip of the current branch that are not in the history
39 that leads to the <since> to be output.
40
412. Generic <revision range> expression (see "SPECIFYING
9d83e382 42 REVISIONS" section in linkgit:gitrevisions[7]) means the
2f6a3823
JH
43 commits in the specified range.
44
2d266f9d
TR
45The first rule takes precedence in the case of a single <commit>. To
46apply the second rule, i.e., format everything since the beginning of
dce5ef14
BG
47history up until <commit>, use the '\--root' option: `git format-patch
48\--root <commit>`. If you want to format only <commit> itself, you
49can do this with `git format-patch -1 <commit>`.
8a1d076e 50
e6ff0f42 51By default, each output file is numbered sequentially from 1, and uses the
2052d146 52first line of the commit message (massaged for pathname safety) as
dce5ef14 53the filename. With the `--numbered-files` option, the output file names
e6ff0f42
JL
54will only be numbers, without the first line of the commit appended.
55The names of the output files are printed to standard
dce5ef14 56output, unless the `--stdout` option is specified.
66f04f38 57
dce5ef14 58If `-o` is specified, output files are created in <dir>. Otherwise
2052d146 59they are created in the current working directory.
35ef3a4c 60
a567fdcb
BG
61By default, the subject of a single patch is "[PATCH] First Line" and
62the subject when multiple patches are output is "[PATCH n/m] First
dce5ef14
BG
63Line". To force 1/1 to be added for a single patch, use `-n`. To omit
64patch numbers from the subject, use `-N`.
35ef3a4c 65
dce5ef14
BG
66If given `--thread`, `git-format-patch` will generate `In-Reply-To` and
67`References` headers to make the second and subsequent patch mails appear
68as replies to the first mail; this also generates a `Message-Id` header to
cc35de84 69reference.
7fc9d69f
JH
70
71OPTIONS
72-------
c1a95fa6 73:git-format-patch: 1
b8105375
BG
74include::diff-options.txt[]
75
ed5f07a6 76-<n>::
2c642ed8 77 Prepare patches from the topmost <n> commits.
ed5f07a6 78
3240240f
SB
79-o <dir>::
80--output-directory <dir>::
35ef3a4c 81 Use <dir> to store the resulting files, instead of the
efd02016 82 current working directory.
35ef3a4c 83
3240240f
SB
84-n::
85--numbered::
a567fdcb 86 Name output in '[PATCH n/m]' format, even with a single patch.
35ef3a4c 87
3240240f
SB
88-N::
89--no-numbered::
49604a4d
BG
90 Name output in '[PATCH]' format.
91
2052d146
DS
92--start-number <n>::
93 Start numbering the patches at <n> instead of 1.
94
e6ff0f42
JL
95--numbered-files::
96 Output file names will be a simple number sequence
97 without the default first line of the commit appended.
e6ff0f42 98
3240240f
SB
99-k::
100--keep-subject::
35ef3a4c
JH
101 Do not strip/add '[PATCH]' from the first line of the
102 commit log message.
103
3240240f
SB
104-s::
105--signoff::
6f855371
NW
106 Add `Signed-off-by:` line to the commit message, using
107 the committer identity of yourself.
108
54ba6013 109--stdout::
2052d146
DS
110 Print all commits to the standard output in mbox format,
111 instead of creating a file for each one.
7fc9d69f 112
c112f689
JS
113--attach[=<boundary>]::
114 Create multipart/mixed attachment, the first part of
115 which is the commit message and the patch itself in the
dce5ef14 116 second part, with `Content-Disposition: attachment`.
c112f689 117
0db5260b
JW
118--no-attach::
119 Disable the creation of an attachment, overriding the
120 configuration setting.
121
c112f689
JS
122--inline[=<boundary>]::
123 Create multipart/mixed attachment, the first part of
124 which is the commit message and the patch itself in the
dce5ef14 125 second part, with `Content-Disposition: inline`.
a15a44ef 126
30984ed2 127--thread[=<style>]::
f693b7e9 128--no-thread::
dce5ef14 129 Controls addition of `In-Reply-To` and `References` headers to
f693b7e9 130 make the second and subsequent mails appear as replies to the
dce5ef14 131 first. Also controls generation of the `Message-Id` header to
f693b7e9 132 reference.
30984ed2
TR
133+
134The optional <style> argument can be either `shallow` or `deep`.
fd1ff306 135'shallow' threading makes every mail a reply to the head of the
30984ed2 136series, where the head is chosen from the cover letter, the
fd1ff306 137`\--in-reply-to`, and the first patch mail, in this order. 'deep'
f693b7e9
YD
138threading makes every mail a reply to the previous one.
139+
dce5ef14
BG
140The default is `--no-thread`, unless the 'format.thread' configuration
141is set. If `--thread` is specified without a style, it defaults to the
f693b7e9
YD
142style specified by 'format.thread' if any, or else `shallow`.
143+
144Beware that the default for 'git send-email' is to thread emails
dce5ef14
BG
145itself. If you want `git format-patch` to take care of threading, you
146will want to ensure that threading is disabled for `git send-email`.
28ffb898 147
da56645d 148--in-reply-to=Message-Id::
dce5ef14 149 Make the first mail (or all the mails with `--no-thread`) appear as a
da56645d
JT
150 reply to the given Message-Id, which avoids breaking threads to
151 provide a new patch series.
152
cc75ad67
DK
153--ignore-if-in-upstream::
154 Do not include a patch that matches a commit in
155 <until>..<since>. This will examine all patches reachable
156 from <since> but not from <until> and compare them with the
157 patches being generated, and any patch that matches is
158 ignored.
159
2d9e4a47
RJ
160--subject-prefix=<Subject-Prefix>::
161 Instead of the standard '[PATCH]' prefix in the subject
162 line, instead use '[<Subject-Prefix>]'. This
163 allows for useful naming of a patch series, and can be
dce5ef14 164 combined with the `--numbered` option.
2d9e4a47 165
ae6c098f
SD
166--to=<email>::
167 Add a `To:` header to the email headers. This is in addition
168 to any configured headers, and may be used multiple times.
169
736cc67d 170--cc=<email>::
dce5ef14 171 Add a `Cc:` header to the email headers. This is in addition
736cc67d
DB
172 to any configured headers, and may be used multiple times.
173
d7d9c2d0
MH
174--add-header=<header>::
175 Add an arbitrary header to the email headers. This is in addition
176 to any configured headers, and may be used multiple times.
dce5ef14 177 For example, `--add-header="Organization: git-foo"`
d7d9c2d0 178
a5a27c79 179--cover-letter::
f4912391
MM
180 In addition to the patches, generate a cover letter file
181 containing the shortlog and the overall diffstat. You can
182 fill in a description in the file before sending it out.
a5a27c79 183
6622d9c7
SB
184--[no]-signature=<signature>::
185 Add a signature to each message produced. Per RFC 3676 the signature
186 is separated from the body by a line with '-- ' on it. If the
187 signature option is omitted the signature defaults to the git version
188 number.
189
03eeaeae 190--suffix=.<sfx>::
917a8f89 191 Instead of using `.patch` as the suffix for generated
02783075 192 filenames, use specified suffix. A common alternative is
50710ce4
SB
193 `--suffix=.txt`. Leaving this empty will remove the `.patch`
194 suffix.
03eeaeae 195+
50710ce4
SB
196Note that the leading character does not have to be a dot; for example,
197you can use `--suffix=-patch` to get `0001-description-of-my-change-patch`.
03eeaeae 198
37c22a4b 199--no-binary::
50710ce4
SB
200 Do not output contents of changes in binary files, instead
201 display a notice that those files changed. Patches generated
202 using this option cannot be applied properly, but they are
203 still useful for code review.
37c22a4b 204
2d266f9d
TR
205--root::
206 Treat the revision argument as a <revision range>, even if it
207 is just a single commit (that would normally be treated as a
208 <since>). Note that root commits included in the specified
209 range are always formatted as creation patches, independently
210 of this flag.
211
96ce6d26
MM
212CONFIGURATION
213-------------
50710ce4
SB
214You can specify extra mail header lines to be added to each message,
215defaults for the subject prefix and file suffix, number patches when
ae6c098f
SD
216outputting more than one patch, add "To" or "Cc:" headers, configure
217attachments, and sign off patches with configuration variables.
96ce6d26 218
917a8f89 219------------
96ce6d26 220[format]
7f9d77f2
JN
221 headers = "Organization: git-foo\n"
222 subjectprefix = CHANGE
223 suffix = .txt
224 numbered = auto
ae6c098f 225 to = <email>
fe8928e6 226 cc = <email>
0db5260b 227 attach [ = mime-boundary-string ]
1d1876e9 228 signoff = true
917a8f89 229------------
03eeaeae 230
96ce6d26 231
e0d48279
JN
232DISCUSSION
233----------
234
235The patch produced by 'git format-patch' is in UNIX mailbox format,
236with a fixed "magic" time stamp to indicate that the file is output
237from format-patch rather than a real mailbox, like so:
238
239------------
240From 8f72bad1baf19a53459661343e21d6491c3908d3 Mon Sep 17 00:00:00 2001
241From: Tony Luck <tony.luck@intel.com>
242Date: Tue, 13 Jul 2010 11:42:54 -0700
243Subject: [PATCH] =?UTF-8?q?[IA64]=20Put=20ia64=20config=20files=20on=20the=20?=
244 =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig=20diet?=
245MIME-Version: 1.0
246Content-Type: text/plain; charset=UTF-8
247Content-Transfer-Encoding: 8bit
248
249arch/arm config files were slimmed down using a python script
250(See commit c2330e286f68f1c408b4aa6515ba49d57f05beae comment)
251
252Do the same for ia64 so we can have sleek & trim looking
253...
254------------
255
256Typically it will be placed in a MUA's drafts folder, edited to add
257timely commentary that should not go in the changelog after the three
258dashes, and then sent as a message whose body, in our example, starts
259with "arch/arm config files were...". On the receiving end, readers
260can save interesting patches in a UNIX mailbox and apply them with
261linkgit:git-am[1].
262
263When a patch is part of an ongoing discussion, the patch generated by
264'git format-patch' can be tweaked to take advantage of the 'git am
265--scissors' feature. After your response to the discussion comes a
266line that consists solely of "`-- >8 --`" (scissors and perforation),
267followed by the patch with unnecessary header fields removed:
268
269------------
270...
271> So we should do such-and-such.
272
273Makes sense to me. How about this patch?
274
275-- >8 --
276Subject: [IA64] Put ia64 config files on the Uwe Kleine-König diet
277
278arch/arm config files were slimmed down using a python script
279...
280------------
281
282When sending a patch this way, most often you are sending your own
283patch, so in addition to the "`From $SHA1 $magic_timestamp`" marker you
284should omit `From:` and `Date:` lines from the patch file. The patch
285title is likely to be different from the subject of the discussion the
286patch is in response to, so it is likely that you would want to keep
287the Subject: line, like the example above.
288
57756161
JN
289Checking for patch corruption
290~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
291Many mailers if not set up properly will corrupt whitespace. Here are
292two common types of corruption:
293
294* Empty context lines that do not have _any_ whitespace.
295
296* Non-empty context lines that have one extra whitespace at the
297 beginning.
298
299One way to test if your MUA is set up correctly is:
300
301* Send the patch to yourself, exactly the way you would, except
302 with To: and Cc: lines that do not contain the list and
303 maintainer address.
304
305* Save that patch to a file in UNIX mailbox format. Call it a.patch,
306 say.
307
308* Apply it:
309
310 $ git fetch <project> master:test-apply
311 $ git checkout test-apply
312 $ git reset --hard
313 $ git am a.patch
314
315If it does not apply correctly, there can be various reasons.
316
317* The patch itself does not apply cleanly. That is _bad_ but
318 does not have much to do with your MUA. You might want to rebase
319 the patch with linkgit:git-rebase[1] before regenerating it in
320 this case.
321
322* The MUA corrupted your patch; "am" would complain that
323 the patch does not apply. Look in the .git/rebase-apply/ subdirectory and
324 see what 'patch' file contains and check for the common
325 corruption patterns mentioned above.
326
327* While at it, check the 'info' and 'final-commit' files as well.
328 If what is in 'final-commit' is not exactly what you would want to
329 see in the commit log message, it is very likely that the
330 receiver would end up hand editing the log message when applying
331 your patch. Things like "Hi, this is my first patch.\n" in the
332 patch e-mail should come after the three-dash line that signals
333 the end of the commit message.
334
e0d48279 335
28ffb898
JH
336EXAMPLES
337--------
338
921177f5 339* Extract commits between revisions R1 and R2, and apply them on top of
0b444cdb 340the current branch using 'git am' to cherry-pick them:
921177f5
CC
341+
342------------
467c0197 343$ git format-patch -k --stdout R1..R2 | git am -3 -k
921177f5
CC
344------------
345
346* Extract all commits which are in the current branch but not in the
347origin branch:
348+
349------------
350$ git format-patch origin
351------------
352+
353For each commit a separate file is created in the current directory.
354
355* Extract all commits that lead to 'origin' since the inception of the
356project:
357+
358------------
9c67c757 359$ git format-patch --root origin
921177f5
CC
360------------
361
362* The same as the previous one:
363+
364------------
365$ git format-patch -M -B origin
366------------
367+
368Additionally, it detects and handles renames and complete rewrites
369intelligently to produce a renaming patch. A renaming patch reduces
50710ce4
SB
370the amount of text output, and generally makes it easier to review.
371Note that non-git "patch" programs won't understand renaming patches, so
921177f5
CC
372use it only when you know the recipient uses git to apply your patch.
373
374* Extract three topmost commits from the current branch and format them
375as e-mailable patches:
376+
377------------
378$ git format-patch -3
379------------
28ffb898 380
56ae8df5 381SEE ALSO
28ffb898 382--------
5162e697 383linkgit:git-am[1], linkgit:git-send-email[1]
28ffb898 384
7fc9d69f
JH
385GIT
386---
9e1f0a85 387Part of the linkgit:git[1] suite