sha1_file.c: introduce a null_oid constant
[git/git.git] / Documentation / git-format-patch.txt
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1git-format-patch(1)
2===================
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3
4NAME
5----
7bd7f280 6git-format-patch - Prepare patches for e-mail submission
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7
8
9SYNOPSIS
10--------
353ce815 11[verse]
50710ce4 12'git format-patch' [-k] [(-o|--output-directory) <dir> | --stdout]
f693b7e9 13 [--no-thread | --thread[=<style>]]
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14 [(--attach|--inline)[=<boundary>] | --no-attach]
15 [-s | --signoff]
6622d9c7 16 [--signature=<signature> | --no-signature]
7022650f 17 [--signature-file=<file>]
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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]
7952ea66 22 [--subject-prefix=Subject-Prefix] [(--reroll-count|-v) <n>]
ae6c098f 23 [--to=<email>] [--cc=<email>]
2a4c2607 24 [--[no-]cover-letter] [--quiet] [--notes[=<ref>]]
50710ce4 25 [<common diff options>]
8a1d076e 26 [ <since> | <revision range> ]
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27
28DESCRIPTION
29-----------
2052d146 30
8a1d076e 31Prepare each commit with its patch in
2052d146 32one file per commit, formatted to resemble UNIX mailbox format.
2052d146 33The output of this command is convenient for e-mail submission or
0b444cdb 34for use with 'git am'.
35ef3a4c 35
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36There are two ways to specify which commits to operate on.
37
381. A single commit, <since>, specifies that the commits leading
39 to the tip of the current branch that are not in the history
40 that leads to the <since> to be output.
41
422. Generic <revision range> expression (see "SPECIFYING
9d83e382 43 REVISIONS" section in linkgit:gitrevisions[7]) means the
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44 commits in the specified range.
45
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46The first rule takes precedence in the case of a single <commit>. To
47apply the second rule, i.e., format everything since the beginning of
dce5ef14 48history up until <commit>, use the '\--root' option: `git format-patch
6cf378f0 49--root <commit>`. If you want to format only <commit> itself, you
dce5ef14 50can do this with `git format-patch -1 <commit>`.
8a1d076e 51
e6ff0f42 52By default, each output file is numbered sequentially from 1, and uses the
2052d146 53first line of the commit message (massaged for pathname safety) as
dce5ef14 54the filename. With the `--numbered-files` option, the output file names
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55will only be numbers, without the first line of the commit appended.
56The names of the output files are printed to standard
dce5ef14 57output, unless the `--stdout` option is specified.
66f04f38 58
dce5ef14 59If `-o` is specified, output files are created in <dir>. Otherwise
2052d146 60they are created in the current working directory.
35ef3a4c 61
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62By default, the subject of a single patch is "[PATCH] " followed by
63the concatenation of lines from the commit message up to the first blank
64line (see the DISCUSSION section of linkgit:git-commit[1]).
65
66When multiple patches are output, the subject prefix will instead be
67"[PATCH n/m] ". To force 1/1 to be added for a single patch, use `-n`.
68To omit patch numbers from the subject, use `-N`.
35ef3a4c 69
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70If given `--thread`, `git-format-patch` will generate `In-Reply-To` and
71`References` headers to make the second and subsequent patch mails appear
72as replies to the first mail; this also generates a `Message-Id` header to
cc35de84 73reference.
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74
75OPTIONS
76-------
c1a95fa6 77:git-format-patch: 1
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78include::diff-options.txt[]
79
ed5f07a6 80-<n>::
2c642ed8 81 Prepare patches from the topmost <n> commits.
ed5f07a6 82
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83-o <dir>::
84--output-directory <dir>::
35ef3a4c 85 Use <dir> to store the resulting files, instead of the
efd02016 86 current working directory.
35ef3a4c 87
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88-n::
89--numbered::
a567fdcb 90 Name output in '[PATCH n/m]' format, even with a single patch.
35ef3a4c 91
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92-N::
93--no-numbered::
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94 Name output in '[PATCH]' format.
95
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96--start-number <n>::
97 Start numbering the patches at <n> instead of 1.
98
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99--numbered-files::
100 Output file names will be a simple number sequence
101 without the default first line of the commit appended.
e6ff0f42 102
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103-k::
104--keep-subject::
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105 Do not strip/add '[PATCH]' from the first line of the
106 commit log message.
107
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108-s::
109--signoff::
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110 Add `Signed-off-by:` line to the commit message, using
111 the committer identity of yourself.
112
54ba6013 113--stdout::
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114 Print all commits to the standard output in mbox format,
115 instead of creating a file for each one.
7fc9d69f 116
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117--attach[=<boundary>]::
118 Create multipart/mixed attachment, the first part of
119 which is the commit message and the patch itself in the
dce5ef14 120 second part, with `Content-Disposition: attachment`.
c112f689 121
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122--no-attach::
123 Disable the creation of an attachment, overriding the
124 configuration setting.
125
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126--inline[=<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: inline`.
a15a44ef 130
30984ed2 131--thread[=<style>]::
f693b7e9 132--no-thread::
dce5ef14 133 Controls addition of `In-Reply-To` and `References` headers to
f693b7e9 134 make the second and subsequent mails appear as replies to the
dce5ef14 135 first. Also controls generation of the `Message-Id` header to
f693b7e9 136 reference.
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137+
138The optional <style> argument can be either `shallow` or `deep`.
fd1ff306 139'shallow' threading makes every mail a reply to the head of the
30984ed2 140series, where the head is chosen from the cover letter, the
6cf378f0 141`--in-reply-to`, and the first patch mail, in this order. 'deep'
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142threading makes every mail a reply to the previous one.
143+
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144The default is `--no-thread`, unless the 'format.thread' configuration
145is set. If `--thread` is specified without a style, it defaults to the
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146style specified by 'format.thread' if any, or else `shallow`.
147+
148Beware that the default for 'git send-email' is to thread emails
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149itself. If you want `git format-patch` to take care of threading, you
150will want to ensure that threading is disabled for `git send-email`.
28ffb898 151
da56645d 152--in-reply-to=Message-Id::
dce5ef14 153 Make the first mail (or all the mails with `--no-thread`) appear as a
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154 reply to the given Message-Id, which avoids breaking threads to
155 provide a new patch series.
156
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157--ignore-if-in-upstream::
158 Do not include a patch that matches a commit in
159 <until>..<since>. This will examine all patches reachable
160 from <since> but not from <until> and compare them with the
161 patches being generated, and any patch that matches is
162 ignored.
163
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164--subject-prefix=<Subject-Prefix>::
165 Instead of the standard '[PATCH]' prefix in the subject
166 line, instead use '[<Subject-Prefix>]'. This
167 allows for useful naming of a patch series, and can be
dce5ef14 168 combined with the `--numbered` option.
2d9e4a47 169
7952ea66 170-v <n>::
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171--reroll-count=<n>::
172 Mark the series as the <n>-th iteration of the topic. The
d614f075 173 output filenames have `v<n>` prepended to them, and the
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174 subject prefix ("PATCH" by default, but configurable via the
175 `--subject-prefix` option) has ` v<n>` appended to it. E.g.
176 `--reroll-count=4` may produce `v4-0001-add-makefile.patch`
177 file that has "Subject: [PATCH v4 1/20] Add makefile" in it.
178
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179--to=<email>::
180 Add a `To:` header to the email headers. This is in addition
181 to any configured headers, and may be used multiple times.
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182 The negated form `--no-to` discards all `To:` headers added so
183 far (from config or command line).
ae6c098f 184
736cc67d 185--cc=<email>::
dce5ef14 186 Add a `Cc:` header to the email headers. This is in addition
736cc67d 187 to any configured headers, and may be used multiple times.
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188 The negated form `--no-cc` discards all `Cc:` headers added so
189 far (from config or command line).
736cc67d 190
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191--from::
192--from=<ident>::
193 Use `ident` in the `From:` header of each commit email. If the
194 author ident of the commit is not textually identical to the
195 provided `ident`, place a `From:` header in the body of the
196 message with the original author. If no `ident` is given, use
197 the committer ident.
198+
199Note that this option is only useful if you are actually sending the
200emails and want to identify yourself as the sender, but retain the
201original author (and `git am` will correctly pick up the in-body
202header). Note also that `git send-email` already handles this
203transformation for you, and this option should not be used if you are
204feeding the result to `git send-email`.
205
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206--add-header=<header>::
207 Add an arbitrary header to the email headers. This is in addition
208 to any configured headers, and may be used multiple times.
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209 For example, `--add-header="Organization: git-foo"`.
210 The negated form `--no-add-header` discards *all* (`To:`,
211 `Cc:`, and custom) headers added so far from config or command
212 line.
d7d9c2d0 213
2a4c2607 214--[no-]cover-letter::
f4912391 215 In addition to the patches, generate a cover letter file
561d2b79 216 containing the branch description, shortlog and the overall diffstat. You can
f4912391 217 fill in a description in the file before sending it out.
a5a27c79 218
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219--notes[=<ref>]::
220 Append the notes (see linkgit:git-notes[1]) for the commit
221 after the three-dash line.
222+
223The expected use case of this is to write supporting explanation for
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224the commit that does not belong to the commit log message proper,
225and include it with the patch submission. While one can simply write
226these explanations after `format-patch` has run but before sending,
2de9b711 227keeping them as Git notes allows them to be maintained between versions
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228of the patch series (but see the discussion of the `notes.rewrite`
229configuration options in linkgit:git-notes[1] to use this workflow).
e422c0cf 230
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231--[no]-signature=<signature>::
232 Add a signature to each message produced. Per RFC 3676 the signature
233 is separated from the body by a line with '-- ' on it. If the
2de9b711 234 signature option is omitted the signature defaults to the Git version
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235 number.
236
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237--signature-file=<file>::
238 Works just like --signature except the signature is read from a file.
239
03eeaeae 240--suffix=.<sfx>::
917a8f89 241 Instead of using `.patch` as the suffix for generated
02783075 242 filenames, use specified suffix. A common alternative is
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243 `--suffix=.txt`. Leaving this empty will remove the `.patch`
244 suffix.
03eeaeae 245+
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246Note that the leading character does not have to be a dot; for example,
247you can use `--suffix=-patch` to get `0001-description-of-my-change-patch`.
03eeaeae 248
b7df098c 249-q::
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250--quiet::
251 Do not print the names of the generated files to standard output.
252
37c22a4b 253--no-binary::
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254 Do not output contents of changes in binary files, instead
255 display a notice that those files changed. Patches generated
256 using this option cannot be applied properly, but they are
257 still useful for code review.
37c22a4b 258
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259--root::
260 Treat the revision argument as a <revision range>, even if it
261 is just a single commit (that would normally be treated as a
262 <since>). Note that root commits included in the specified
263 range are always formatted as creation patches, independently
264 of this flag.
265
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266CONFIGURATION
267-------------
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268You can specify extra mail header lines to be added to each message,
269defaults for the subject prefix and file suffix, number patches when
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270outputting more than one patch, add "To" or "Cc:" headers, configure
271attachments, and sign off patches with configuration variables.
96ce6d26 272
917a8f89 273------------
96ce6d26 274[format]
7f9d77f2 275 headers = "Organization: git-foo\n"
da0005b8 276 subjectPrefix = CHANGE
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277 suffix = .txt
278 numbered = auto
ae6c098f 279 to = <email>
fe8928e6 280 cc = <email>
0db5260b 281 attach [ = mime-boundary-string ]
da0005b8 282 signOff = true
2a4c2607 283 coverletter = auto
917a8f89 284------------
03eeaeae 285
96ce6d26 286
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287DISCUSSION
288----------
289
290The patch produced by 'git format-patch' is in UNIX mailbox format,
291with a fixed "magic" time stamp to indicate that the file is output
292from format-patch rather than a real mailbox, like so:
293
294------------
295From 8f72bad1baf19a53459661343e21d6491c3908d3 Mon Sep 17 00:00:00 2001
296From: Tony Luck <tony.luck@intel.com>
297Date: Tue, 13 Jul 2010 11:42:54 -0700
298Subject: [PATCH] =?UTF-8?q?[IA64]=20Put=20ia64=20config=20files=20on=20the=20?=
299 =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig=20diet?=
300MIME-Version: 1.0
301Content-Type: text/plain; charset=UTF-8
302Content-Transfer-Encoding: 8bit
303
304arch/arm config files were slimmed down using a python script
305(See commit c2330e286f68f1c408b4aa6515ba49d57f05beae comment)
306
307Do the same for ia64 so we can have sleek & trim looking
308...
309------------
310
311Typically it will be placed in a MUA's drafts folder, edited to add
312timely commentary that should not go in the changelog after the three
313dashes, and then sent as a message whose body, in our example, starts
314with "arch/arm config files were...". On the receiving end, readers
315can save interesting patches in a UNIX mailbox and apply them with
316linkgit:git-am[1].
317
318When a patch is part of an ongoing discussion, the patch generated by
319'git format-patch' can be tweaked to take advantage of the 'git am
320--scissors' feature. After your response to the discussion comes a
321line that consists solely of "`-- >8 --`" (scissors and perforation),
322followed by the patch with unnecessary header fields removed:
323
324------------
325...
326> So we should do such-and-such.
327
328Makes sense to me. How about this patch?
329
330-- >8 --
331Subject: [IA64] Put ia64 config files on the Uwe Kleine-König diet
332
333arch/arm config files were slimmed down using a python script
334...
335------------
336
337When sending a patch this way, most often you are sending your own
338patch, so in addition to the "`From $SHA1 $magic_timestamp`" marker you
339should omit `From:` and `Date:` lines from the patch file. The patch
340title is likely to be different from the subject of the discussion the
341patch is in response to, so it is likely that you would want to keep
342the Subject: line, like the example above.
343
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344Checking for patch corruption
345~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
346Many mailers if not set up properly will corrupt whitespace. Here are
347two common types of corruption:
348
349* Empty context lines that do not have _any_ whitespace.
350
351* Non-empty context lines that have one extra whitespace at the
352 beginning.
353
354One way to test if your MUA is set up correctly is:
355
356* Send the patch to yourself, exactly the way you would, except
357 with To: and Cc: lines that do not contain the list and
358 maintainer address.
359
360* Save that patch to a file in UNIX mailbox format. Call it a.patch,
361 say.
362
363* Apply it:
364
365 $ git fetch <project> master:test-apply
366 $ git checkout test-apply
367 $ git reset --hard
368 $ git am a.patch
369
370If it does not apply correctly, there can be various reasons.
371
372* The patch itself does not apply cleanly. That is _bad_ but
373 does not have much to do with your MUA. You might want to rebase
374 the patch with linkgit:git-rebase[1] before regenerating it in
375 this case.
376
377* The MUA corrupted your patch; "am" would complain that
378 the patch does not apply. Look in the .git/rebase-apply/ subdirectory and
379 see what 'patch' file contains and check for the common
380 corruption patterns mentioned above.
381
382* While at it, check the 'info' and 'final-commit' files as well.
383 If what is in 'final-commit' is not exactly what you would want to
384 see in the commit log message, it is very likely that the
385 receiver would end up hand editing the log message when applying
386 your patch. Things like "Hi, this is my first patch.\n" in the
387 patch e-mail should come after the three-dash line that signals
388 the end of the commit message.
389
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390MUA-SPECIFIC HINTS
391------------------
392Here are some hints on how to successfully submit patches inline using
393various mailers.
394
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395GMail
396~~~~~
397GMail does not have any way to turn off line wrapping in the web
398interface, so it will mangle any emails that you send. You can however
399use "git send-email" and send your patches through the GMail SMTP server, or
400use any IMAP email client to connect to the google IMAP server and forward
401the emails through that.
402
403For hints on using 'git send-email' to send your patches through the
404GMail SMTP server, see the EXAMPLE section of linkgit:git-send-email[1].
405
406For hints on submission using the IMAP interface, see the EXAMPLE
407section of linkgit:git-imap-send[1].
408
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409Thunderbird
410~~~~~~~~~~~
411By default, Thunderbird will both wrap emails as well as flag
412them as being 'format=flowed', both of which will make the
2de9b711 413resulting email unusable by Git.
dc53151f 414
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415There are three different approaches: use an add-on to turn off line wraps,
416configure Thunderbird to not mangle patches, or use
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417an external editor to keep Thunderbird from mangling the patches.
418
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419Approach #1 (add-on)
420^^^^^^^^^^^^^^^^^^^^
421
422Install the Toggle Word Wrap add-on that is available from
423https://addons.mozilla.org/thunderbird/addon/toggle-word-wrap/
424It adds a menu entry "Enable Word Wrap" in the composer's "Options" menu
425that you can tick off. Now you can compose the message as you otherwise do
426(cut + paste, 'git format-patch' | 'git imap-send', etc), but you have to
427insert line breaks manually in any text that you type.
428
429Approach #2 (configuration)
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430^^^^^^^^^^^^^^^^^^^^^^^^^^^
431Three steps:
432
4331. Configure your mail server composition as plain text:
434 Edit...Account Settings...Composition & Addressing,
435 uncheck "Compose Messages in HTML".
436
4372. Configure your general composition window to not wrap.
438+
439In Thunderbird 2:
440Edit..Preferences..Composition, wrap plain text messages at 0
441+
442In Thunderbird 3:
443Edit..Preferences..Advanced..Config Editor. Search for
444"mail.wrap_long_lines".
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445Toggle it to make sure it is set to `false`. Also, search for
446"mailnews.wraplength" and set the value to 0.
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447
4483. Disable the use of format=flowed:
449Edit..Preferences..Advanced..Config Editor. Search for
450"mailnews.send_plaintext_flowed".
451Toggle it to make sure it is set to `false`.
452
453After that is done, you should be able to compose email as you
454otherwise would (cut + paste, 'git format-patch' | 'git imap-send', etc),
455and the patches will not be mangled.
456
b8959605 457Approach #3 (external editor)
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458^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
459
460The following Thunderbird extensions are needed:
461AboutConfig from http://aboutconfig.mozdev.org/ and
462External Editor from http://globs.org/articles.php?lng=en&pg=8
463
4641. Prepare the patch as a text file using your method of choice.
465
4662. Before opening a compose window, use Edit->Account Settings to
467 uncheck the "Compose messages in HTML format" setting in the
468 "Composition & Addressing" panel of the account to be used to
469 send the patch.
470
4713. In the main Thunderbird window, 'before' you open the compose
472 window for the patch, use Tools->about:config to set the
473 following to the indicated values:
474+
475----------
476 mailnews.send_plaintext_flowed => false
477 mailnews.wraplength => 0
478----------
479
4804. Open a compose window and click the external editor icon.
481
4825. In the external editor window, read in the patch file and exit
483 the editor normally.
484
485Side note: it may be possible to do step 2 with
486about:config and the following settings but no one's tried yet.
487
488----------
489 mail.html_compose => false
490 mail.identity.default.compose_html => false
491 mail.identity.id?.compose_html => false
492----------
493
494There is a script in contrib/thunderbird-patch-inline which can help
495you include patches with Thunderbird in an easy way. To use it, do the
496steps above and then use the script as the external editor.
497
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498KMail
499~~~~~
500This should help you to submit patches inline using KMail.
501
5021. Prepare the patch as a text file.
503
5042. Click on New Mail.
505
5063. Go under "Options" in the Composer window and be sure that
507 "Word wrap" is not set.
508
5094. Use Message -> Insert file... and insert the patch.
510
5115. Back in the compose window: add whatever other text you wish to the
512 message, complete the addressing and subject fields, and press send.
513
e0d48279 514
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515EXAMPLES
516--------
517
921177f5 518* Extract commits between revisions R1 and R2, and apply them on top of
0b444cdb 519the current branch using 'git am' to cherry-pick them:
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520+
521------------
467c0197 522$ git format-patch -k --stdout R1..R2 | git am -3 -k
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523------------
524
525* Extract all commits which are in the current branch but not in the
526origin branch:
527+
528------------
529$ git format-patch origin
530------------
531+
532For each commit a separate file is created in the current directory.
533
534* Extract all commits that lead to 'origin' since the inception of the
535project:
536+
537------------
9c67c757 538$ git format-patch --root origin
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539------------
540
541* The same as the previous one:
542+
543------------
544$ git format-patch -M -B origin
545------------
546+
547Additionally, it detects and handles renames and complete rewrites
548intelligently to produce a renaming patch. A renaming patch reduces
50710ce4 549the amount of text output, and generally makes it easier to review.
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550Note that non-Git "patch" programs won't understand renaming patches, so
551use it only when you know the recipient uses Git to apply your patch.
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552
553* Extract three topmost commits from the current branch and format them
554as e-mailable patches:
555+
556------------
557$ git format-patch -3
558------------
28ffb898 559
56ae8df5 560SEE ALSO
28ffb898 561--------
5162e697 562linkgit:git-am[1], linkgit:git-send-email[1]
28ffb898 563
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564GIT
565---
9e1f0a85 566Part of the linkgit:git[1] suite