Fourth batch for 2.5 cycle
[git.git] / Documentation / SubmittingPatches
Commit [+]AuthorDateLineData
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Junio C Hamano2013-01-01 14:35:22 -08001Here are some guidelines for people who want to contribute their code
2to this software.
31408251 Junio C Hamano2005-08-12 23:48:09 -07003
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Ramkumar Ramachandra2010-04-19 01:24:20 +05304(0) Decide what to base your work on.
5
6In general, always base your work on the oldest branch that your
7change is relevant to.
8
9 - A bugfix should be based on 'maint' in general. If the bug is not
10 present in 'maint', base it on 'master'. For a bug that's not yet
11 in 'master', find the topic that introduces the regression, and
12 base your work on the tip of the topic.
13
14 - A new feature should be based on 'master' in general. If the new
15 feature depends on a topic that is in 'pu', but not in 'master',
16 base your work on the tip of that topic.
17
18 - Corrections and enhancements to a topic not yet in 'master' should
19 be based on the tip of that topic. If the topic has not been merged
20 to 'next', it's alright to add a note to squash minor corrections
21 into the series.
22
23 - In the exceptional case that a new feature depends on several topics
24 not in 'master', start working on 'next' or 'pu' privately and send
25 out patches for discussion. Before the final merge, you may have to
26 wait until some of the dependent topics graduate to 'master', and
27 rebase your work.
28
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Junio C Hamano2013-01-01 14:37:56 -080029 - Some parts of the system have dedicated maintainers with their own
30 repositories (see the section "Subsystems" below). Changes to
31 these parts should be based on their trees.
32
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Ramkumar Ramachandra2010-04-19 01:24:20 +053033To find the tip of a topic branch, run "git log --first-parent
34master..pu" and look for the merge commit. The second parent of this
35commit is the tip of the topic branch.
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Junio C Hamano2005-08-12 23:48:09 -070036
37(1) Make separate commits for logically separate changes.
38
39Unless your patch is really trivial, you should not be sending
40out a patch that was generated between your working tree and
41your commit head. Instead, always make a commit with complete
42commit message and generate a series of patches from your
43repository. It is a good discipline.
44
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Junio C Hamano2011-03-08 16:58:19 -080045Give an explanation for the change(s) that is detailed enough so
46that people can judge if it is good thing to do, without reading
47the actual patch text to determine how well the code does what
48the explanation promises to do.
31408251 Junio C Hamano2005-08-12 23:48:09 -070049
45d2b286 Junio C Hamano2006-02-17 16:15:26 -080050If your description starts to get too long, that's a sign that you
31408251 Junio C Hamano2005-08-12 23:48:09 -070051probably need to split up your commit to finer grained pieces.
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Sam Vilain2009-04-28 02:38:47 +120052That being said, patches which plainly describe the things that
53help reviewers check the patch, and future maintainers understand
54the code, are the most beautiful patches. Descriptions that summarise
55the point in the subject well, and describe the motivation for the
56change, the approach taken by the change, and if relevant how this
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Junio C Hamano2011-03-08 16:58:19 -080057differs substantially from the prior version, are all good things
58to have.
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Junio C Hamano2014-11-24 09:43:29 -080060Make sure that you have tests for the bug you are fixing. See
61t/README for guidance.
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Junio C Hamano2013-01-01 15:19:00 -080062
63When adding a new feature, make sure that you have new tests to show
64the feature triggers the new behaviour when it should, and to show the
65feature does not trigger when it shouldn't. Also make sure that the
66test suite passes after your commit. Do not forget to update the
67documentation to describe the updated behaviour.
68
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Marc Branchaud2013-08-01 14:49:54 -040069Speaking of the documentation, it is currently a liberal mixture of US
70and UK English norms for spelling and grammar, which is somewhat
71unfortunate. A huge patch that touches the files all over the place
72only to correct the inconsistency is not welcome, though. Potential
73clashes with other changes that can result from such a patch are not
74worth it. We prefer to gradually reconcile the inconsistencies in
75favor of US English, with small and easily digestible patches, as a
76side effect of doing some other real work in the vicinity (e.g.
77rewriting a paragraph for clarity, while turning en_UK spelling to
78en_US). Obvious typographical fixes are much more welcomed ("teh ->
79"the"), preferably submitted as independent patches separate from
80other documentation changes.
81
82Oh, another thing. We are picky about whitespaces. Make sure your
45d2b286 Junio C Hamano2006-02-17 16:15:26 -080083changes do not trigger errors with the sample pre-commit hook shipped
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Bill Lear2007-01-27 07:21:53 -060084in templates/hooks--pre-commit. To help ensure this does not happen,
85run git diff --check on your changes before you commit.
31408251 Junio C Hamano2005-08-12 23:48:09 -070086
31408251 Junio C Hamano2005-08-12 23:48:09 -070087
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Junio C Hamano2013-01-01 15:19:00 -080088(2) Describe your changes well.
89
90The first line of the commit message should be a short description (50
91characters is the soft limit, see DISCUSSION in git-commit(1)), and
92should skip the full stop. It is also conventional in most cases to
93prefix the first line with "area: " where the area is a filename or
94identifier for the general area of the code being modified, e.g.
95
96 . archive: ustar header checksum is computed unsigned
97 . git-cherry-pick.txt: clarify the use of revision range notation
98
99If in doubt which identifier to use, run "git log --no-merges" on the
100files you are modifying to see the current conventions.
101
102The body should provide a meaningful commit message, which:
103
104 . explains the problem the change tries to solve, iow, what is wrong
105 with the current code without the change.
106
107 . justifies the way the change solves the problem, iow, why the
108 result with the change is better.
109
110 . alternate solutions considered but discarded, if any.
111
112Describe your changes in imperative mood, e.g. "make xyzzy do frotz"
113instead of "[This patch] makes xyzzy do frotz" or "[I] changed xyzzy
114to do frotz", as if you are giving orders to the codebase to change
115its behaviour. Try to make sure your explanation can be understood
116without external resources. Instead of giving a URL to a mailing list
117archive, summarize the relevant points of the discussion.
118
119
2de9b711 Thomas Ackermann2013-01-21 20:17:53 +0100120(3) Generate your patch using Git tools out of your commits.
45d2b286 Junio C Hamano2006-02-17 16:15:26 -0800121
2de9b711 Thomas Ackermann2013-01-21 20:17:53 +0100122Git based diff tools generate unidiff which is the preferred format.
45d2b286 Junio C Hamano2006-02-17 16:15:26 -0800123
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Junio C Hamano2005-08-12 23:48:09 -0700124You do not have to be afraid to use -M option to "git diff" or
125"git format-patch", if your patch involves file renames. The
126receiving end can handle them just fine.
127
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Junio C Hamano2013-01-01 15:19:00 -0800128Please make sure your patch does not add commented out debugging code,
129or include any extra files which do not relate to what your patch
130is trying to achieve. Make sure to review
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Junio C Hamano2005-08-12 23:48:09 -0700131your patch after generating it, to ensure accuracy. Before
132sending out, please make sure it cleanly applies to the "master"
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Junio C Hamano2006-02-17 16:15:26 -0800133branch head. If you are preparing a work based on "next" branch,
134that is fine, but please mark it as such.
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Junio C Hamano2005-08-12 23:48:09 -0700135
136
7d5bf87b Junio C Hamano2013-01-01 15:19:00 -0800137(4) Sending your patches.
31408251 Junio C Hamano2005-08-12 23:48:09 -0700138
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Junio C Hamano2015-03-13 00:02:15 -0700139Learn to use format-patch and send-email if possible. These commands
140are optimized for the workflow of sending patches, avoiding many ways
141your existing e-mail client that is optimized for "multipart/*" mime
142type e-mails to corrupt and render your patches unusable.
143
2de9b711 Thomas Ackermann2013-01-21 20:17:53 +0100144People on the Git mailing list need to be able to read and
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Junio C Hamano2005-08-12 23:48:09 -0700145comment on the changes you are submitting. It is important for
146a developer to be able to "quote" your changes, using standard
147e-mail tools, so that they may comment on specific portions of
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René Scharfe2013-11-27 01:28:39 +0100148your code. For this reason, each patch should be submitted
149"inline" in a separate message.
150
151Multiple related patches should be grouped into their own e-mail
152thread to help readers find all parts of the series. To that end,
153send them as replies to either an additional "cover letter" message
154(see below), the first patch, or the respective preceding patch.
155
156If your log message (including your name on the
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Junio C Hamano2013-01-01 15:19:00 -0800157Signed-off-by line) is not writable in ASCII, make sure that
158you send off a message in the correct encoding.
159
160WARNING: Be wary of your MUAs word-wrap
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Junio C Hamano2006-02-17 16:15:26 -0800161corrupting your patch. Do not cut-n-paste your patch; you can
162lose tabs that way if you are not careful.
31408251 Junio C Hamano2005-08-12 23:48:09 -0700163
45d2b286 Junio C Hamano2006-02-17 16:15:26 -0800164It is a common convention to prefix your subject line with
31408251 Junio C Hamano2005-08-12 23:48:09 -0700165[PATCH]. This lets people easily distinguish patches from other
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Junio C Hamano2008-02-03 16:55:21 -0800166e-mail discussions. Use of additional markers after PATCH and
167the closing bracket to mark the nature of the patch is also
168encouraged. E.g. [PATCH/RFC] is often used when the patch is
169not ready to be applied but it is for discussion, [PATCH v2],
170[PATCH v3] etc. are often seen when you are sending an update to
171what you have previously sent.
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Junio C Hamano2005-08-12 23:48:09 -0700172
173"git format-patch" command follows the best current practice to
174format the body of an e-mail message. At the beginning of the
175patch should come your commit message, ending with the
176Signed-off-by: lines, and a line that consists of three dashes,
177followed by the diffstat information and the patch itself. If
178you are forwarding a patch from somebody else, optionally, at
179the beginning of the e-mail message just before the commit
180message starts, you can put a "From: " line to name that person.
181
182You often want to add additional explanation about the patch,
183other than the commit message itself. Place such "cover letter"
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Eric Sunshine2014-12-30 18:30:30 -0500184material between the three-dash line and the diffstat. For
185patches requiring multiple iterations of review and discussion,
186an explanation of changes between each iteration can be kept in
187Git-notes and inserted automatically following the three-dash
188line via `git format-patch --notes`.
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Junio C Hamano2005-08-12 23:48:09 -0700189
190Do not attach the patch as a MIME attachment, compressed or not.
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Junio C Hamano2007-01-17 01:07:27 -0800191Do not let your e-mail client send quoted-printable. Do not let
192your e-mail client send format=flowed which would destroy
193whitespaces in your patches. Many
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Junio C Hamano2005-08-12 23:48:09 -0700194popular e-mail applications will not always transmit a MIME
195attachment as plain text, making it impossible to comment on
196your code. A MIME attachment also takes a bit more time to
197process. This does not decrease the likelihood of your
198MIME-attached change being accepted, but it makes it more likely
199that it will be postponed.
200
201Exception: If your mailer is mangling patches then someone may ask
9847f7e0 Junio C Hamano2005-08-28 17:54:18 -0700202you to re-send them using MIME, that is OK.
31408251 Junio C Hamano2005-08-12 23:48:09 -0700203
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Junio C Hamano2005-08-28 17:54:18 -0700204Do not PGP sign your patch, at least for now. Most likely, your
205maintainer or other people on the list would not have your PGP
206key and would not bother obtaining it anyway. Your patch is not
207judged by who you are; a good patch from an unknown origin has a
208far better chance of being accepted than a patch from a known,
209respected origin that is done poorly or does incorrect things.
210
211If you really really really really want to do a PGP signed
212patch, format it as "multipart/signed", not a text/plain message
213that starts with '-----BEGIN PGP SIGNED MESSAGE-----'. That is
214not a text/plain, it's something else.
215
7d5bf87b Junio C Hamano2013-01-01 15:19:00 -0800216Send your patch with "To:" set to the mailing list, with "cc:" listing
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Ramkumar Ramachandra2010-04-19 01:24:20 +0530217people who are involved in the area you are touching (the output from
218"git blame $path" and "git shortlog --no-merges $path" would help to
7d5bf87b Junio C Hamano2013-01-01 15:19:00 -0800219identify them), to solicit comments and reviews.
04d24455 Junio C Hamano2006-10-24 01:29:27 -0700220
7d5bf87b Junio C Hamano2013-01-01 15:19:00 -0800221After the list reached a consensus that it is a good idea to apply the
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Junio C Hamano2013-01-02 09:31:54 -0800222patch, re-send it with "To:" set to the maintainer [*1*] and "cc:" the
223list [*2*] for inclusion.
31408251 Junio C Hamano2005-08-12 23:48:09 -0700224
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Junio C Hamano2013-01-01 15:19:00 -0800225Do not forget to add trailers such as "Acked-by:", "Reviewed-by:" and
226"Tested-by:" lines as necessary to credit people who helped your
227patch.
04d24455 Junio C Hamano2006-10-24 01:29:27 -0700228
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Junio C Hamano2013-01-02 09:31:54 -0800229 [Addresses]
230 *1* The current maintainer: gitster@pobox.com
231 *2* The mailing list: git@vger.kernel.org
232
31408251 Junio C Hamano2005-08-12 23:48:09 -0700233
7d5bf87b Junio C Hamano2013-01-01 15:19:00 -0800234(5) Sign your work
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Junio C Hamano2005-08-12 23:48:09 -0700235
236To improve tracking of who did what, we've borrowed the
237"sign-off" procedure from the Linux kernel project on patches
48a8c26c Thomas Ackermann2013-01-21 20:16:20 +0100238that are being emailed around. Although core Git is a lot
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Junio C Hamano2005-08-12 23:48:09 -0700239smaller project it is a good discipline to follow it.
240
241The sign-off is a simple line at the end of the explanation for
242the patch, which certifies that you wrote it or otherwise have
243the right to pass it on as a open-source patch. The rules are
244pretty simple: if you can certify the below:
245
246 Developer's Certificate of Origin 1.1
247
248 By making a contribution to this project, I certify that:
249
250 (a) The contribution was created in whole or in part by me and I
251 have the right to submit it under the open source license
252 indicated in the file; or
253
254 (b) The contribution is based upon previous work that, to the best
255 of my knowledge, is covered under an appropriate open source
256 license and I have the right under that license to submit that
257 work with modifications, whether created in whole or in part
258 by me, under the same open source license (unless I am
259 permitted to submit under a different license), as indicated
260 in the file; or
261
262 (c) The contribution was provided directly to me by some other
263 person who certified (a), (b) or (c) and I have not modified
264 it.
265
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Stefan Beller2014-12-17 17:08:15 -0800266 (d) I understand and agree that this project and the contribution
267 are public and that a record of the contribution (including all
268 personal information I submit with it, including my sign-off) is
269 maintained indefinitely and may be redistributed consistent with
270 this project or the open source license(s) involved.
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Junio C Hamano2005-08-12 23:48:09 -0700271
272then you just add a line saying
273
c376d968 Stefan Beller2014-12-17 17:08:15 -0800274 Signed-off-by: Random J Developer <random@developer.example.org>
31408251 Junio C Hamano2005-08-12 23:48:09 -0700275
2de9b711 Thomas Ackermann2013-01-21 20:17:53 +0100276This line can be automatically added by Git if you run the git-commit
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Paolo Ciarrocchi2006-11-21 19:55:20 +0100277command with the -s option.
278
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Junio C Hamano2008-02-03 17:02:28 -0800279Notice that you can place your own Signed-off-by: line when
280forwarding somebody else's patch with the above rules for
281D-C-O. Indeed you are encouraged to do so. Do not forget to
282place an in-body "From: " line at the beginning to properly attribute
283the change to its true author (see (2) above).
284
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Miklos Vajna2008-12-20 01:52:17 +0100285Also notice that a real name is used in the Signed-off-by: line. Please
286don't hide your real name.
287
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Ramkumar Ramachandra2010-10-02 10:07:43 +0530288If you like, you can put extra tags at the end:
289
0353a0c4 Jim Meyering2011-04-13 17:39:40 +02002901. "Reported-by:" is used to credit someone who found the bug that
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Ramkumar Ramachandra2010-10-02 10:07:43 +0530291 the patch attempts to fix.
2922. "Acked-by:" says that the person who is more familiar with the area
293 the patch attempts to modify liked the patch.
2943. "Reviewed-by:", unlike the other tags, can only be offered by the
295 reviewer and means that she is completely satisfied that the patch
296 is ready for application. It is usually offered only after a
297 detailed review.
2984. "Tested-by:" is used to indicate that the person applied the patch
299 and found it to have the desired effect.
300
301You can also create your own tag or use one that's in common usage
302such as "Thanks-to:", "Based-on-patch-by:", or "Mentored-by:".
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Junio C Hamano2005-08-26 23:53:07 -0700303
304------------------------------------------------
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Junio C Hamano2013-01-01 14:37:56 -0800305Subsystems with dedicated maintainers
306
307Some parts of the system have dedicated maintainers with their own
308repositories.
309
310 - git-gui/ comes from git-gui project, maintained by Pat Thoyts:
311
312 git://repo.or.cz/git-gui.git
313
314 - gitk-git/ comes from Paul Mackerras's gitk project:
315
316 git://ozlabs.org/~paulus/gitk
317
318 - po/ comes from the localization coordinator, Jiang Xin:
319
320 https://github.com/git-l10n/git-po/
321
322Patches to these parts should be based on their trees.
323
324------------------------------------------------
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Junio C Hamano2008-02-10 14:09:52 -0800325An ideal patch flow
326
327Here is an ideal patch flow for this project the current maintainer
328suggests to the contributors:
329
330 (0) You come up with an itch. You code it up.
331
332 (1) Send it to the list and cc people who may need to know about
333 the change.
334
335 The people who may need to know are the ones whose code you
336 are butchering. These people happen to be the ones who are
337 most likely to be knowledgeable enough to help you, but
338 they have no obligation to help you (i.e. you ask for help,
339 don't demand). "git log -p -- $area_you_are_modifying" would
340 help you find out who they are.
341
342 (2) You get comments and suggestions for improvements. You may
343 even get them in a "on top of your change" patch form.
344
345 (3) Polish, refine, and re-send to the list and the people who
346 spend their time to improve your patch. Go back to step (2).
347
348 (4) The list forms consensus that the last round of your patch is
faa8fac1 Slavomir Vlcek2014-11-13 00:18:39 +0100349 good. Send it to the maintainer and cc the list.
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Junio C Hamano2008-02-10 14:09:52 -0800350
351 (5) A topic branch is created with the patch and is merged to 'next',
352 and cooked further and eventually graduates to 'master'.
353
354In any time between the (2)-(3) cycle, the maintainer may pick it up
355from the list and queue it to 'pu', in order to make it easier for
356people play with it without having to pick up and apply the patch to
357their trees themselves.
358
359------------------------------------------------
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Matthieu Moy2009-12-30 15:51:22 +0100360Know the status of your patch after submission
361
362* You can use Git itself to find out when your patch is merged in
363 master. 'git pull --rebase' will automatically skip already-applied
364 patches, and will let you know. This works only if you rebase on top
365 of the branch in which your patch has been merged (i.e. it will not
366 tell you if your patch is merged in pu if you rebase on top of
367 master).
368
2de9b711 Thomas Ackermann2013-01-21 20:17:53 +0100369* Read the Git mailing list, the maintainer regularly posts messages
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Matthieu Moy2009-12-30 15:51:22 +0100370 entitled "What's cooking in git.git" and "What's in git.git" giving
371 the status of various proposed changes.
372
373------------------------------------------------
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Junio C Hamano2005-08-26 23:53:07 -0700374MUA specific hints
375
376Some of patches I receive or pick up from the list share common
377patterns of breakage. Please make sure your MUA is set up
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Jonathan Nieder2011-04-14 21:24:01 -0500378properly not to corrupt whitespaces.
379
380See the DISCUSSION section of git-format-patch(1) for hints on
381checking your patch by mailing it to yourself and applying with
382git-am(1).
383
384While you are at it, check the resulting commit log message from
385a trial run of applying the patch. If what is in the resulting
386commit is not exactly what you would want to see, it is very
387likely that your maintainer would end up hand editing the log
388message when he applies your patch. Things like "Hi, this is my
389first patch.\n", if you really want to put in the patch e-mail,
390should come after the three-dash line that signals the end of the
391commit message.
9847f7e0 Junio C Hamano2005-08-28 17:54:18 -0700392
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Junio C Hamano2005-08-26 23:53:07 -0700393
394Pine
395----
396
397(Johannes Schindelin)
398
399I don't know how many people still use pine, but for those poor
400souls it may be good to mention that the quell-flowed-text is
401needed for recent versions.
402
403... the "no-strip-whitespace-before-send" option, too. AFAIK it
404was introduced in 4.60.
405
406(Linus Torvalds)
407
408And 4.58 needs at least this.
409
410---
411diff-tree 8326dd8350be64ac7fc805f6563a1d61ad10d32c (from e886a61f76edf5410573e92e38ce22974f9c40f1)
412Author: Linus Torvalds <torvalds@g5.osdl.org>
413Date: Mon Aug 15 17:23:51 2005 -0700
414
415 Fix pine whitespace-corruption bug
416
417 There's no excuse for unconditionally removing whitespace from
418 the pico buffers on close.
419
420diff --git a/pico/pico.c b/pico/pico.c
421--- a/pico/pico.c
422+++ b/pico/pico.c
423@@ -219,7 +219,9 @@ PICO *pm;
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Junio C Hamano2007-06-07 00:04:01 -0700424 switch(pico_all_done){ /* prepare for/handle final events */
425 case COMP_EXIT : /* already confirmed */
426 packheader();
9740d289 Junio C Hamano2005-08-26 23:53:07 -0700427+#if 0
a6080a0a Junio C Hamano2007-06-07 00:04:01 -0700428 stripwhitespace();
9740d289 Junio C Hamano2005-08-26 23:53:07 -0700429+#endif
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Junio C Hamano2007-06-07 00:04:01 -0700430 c |= COMP_EXIT;
431 break;
432
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Junio C Hamano2005-08-31 11:48:41 -0700434(Daniel Barkalow)
435
436> A patch to SubmittingPatches, MUA specific help section for
437> users of Pine 4.63 would be very much appreciated.
438
439Ah, it looks like a recent version changed the default behavior to do the
440right thing, and inverted the sense of the configuration option. (Either
441that or Gentoo did it.) So you need to set the
442"no-strip-whitespace-before-send" option, unless the option you have is
443"strip-whitespace-before-send", in which case you should avoid checking
444it.
445
9740d289 Junio C Hamano2005-08-26 23:53:07 -0700446
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Jonathan Nieder2011-04-14 21:33:57 -0500447Thunderbird, KMail, GMail
448-------------------------
9740d289 Junio C Hamano2005-08-26 23:53:07 -0700449
dc53151f Jonathan Nieder2011-04-14 21:28:06 -0500450See the MUA-SPECIFIC HINTS section of git-format-patch(1).
e30b217b Junio C Hamano2007-01-17 01:07:27 -0800451
e30b217b
JH
Junio C Hamano2007-01-17 01:07:27 -0800452Gnus
453----
454
455'|' in the *Summary* buffer can be used to pipe the current
456message to an external program, and this is a handy way to drive
457"git am". However, if the message is MIME encoded, what is
458piped into the program is the representation you see in your
459*Article* buffer after unwrapping MIME. This is often not what
460you would want for two reasons. It tends to screw up non ASCII
461characters (most notably in people's names), and also
462whitespaces (fatal in patches). Running 'C-u g' to display the
463message in raw form before using '|' to run the pipe can work
464this problem around.