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[perl5.git] / pod / perlrepository.pod
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1=for comment
2Consistent formatting of this file is achieved with:
3 perl ./Porting/podtidy pod/perlrepository.pod
4
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5=head1 NAME
6
7perlrepository - Using the Perl source repository
8
9=head1 SYNOPSIS
10
dc3c3040 11All of Perl's source code is kept centrally in a Git repository at
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12I<perl5.git.perl.org>. The repository contains many Perl revisions from
13Perl 1 onwards and all the revisions from Perforce, the version control
14system we were using previously. This repository is accessible in
15different ways.
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16
17The full repository takes up about 80MB of disk space. A check out of
7f4ffa9d 18the blead branch (that is, the main development branch, which contains
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19bleadperl, the development version of perl 5) takes up about 160MB of
20disk space (including the repository). A build of bleadperl takes up
21about 200MB (including the repository and the check out).
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22
23=head1 GETTING ACCESS TO THE REPOSITORY
24
25=head2 READ ACCESS VIA THE WEB
26
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27You may access the repository over the web. This allows you to browse
28the tree, see recent commits, subscribe to RSS feeds for the changes,
29search for particular commits and more. You may access it at:
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30
31 http://perl5.git.perl.org/perl.git
32
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33A mirror of the repository is found at:
34
45b194c5 35 http://github.com/mirrors/perl
dc3c3040 36
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37=head2 READ ACCESS VIA GIT
38
39You will need a copy of Git for your computer. You can fetch a copy of
40the repository using the Git protocol (which uses port 9418):
41
e0b2b458 42 % git clone git://perl5.git.perl.org/perl.git perl-git
d7dd28b6 43
f755e97d 44This clones the repository and makes a local copy in the F<perl-git>
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45directory.
46
47If your local network does not allow you to use port 9418, then you can
cf5e7595 48fetch a copy of the repository over HTTP (this is at least 4x slower):
d7dd28b6 49
e0b2b458 50 % git clone http://perl5.git.perl.org/perl.git perl-http
d7dd28b6 51
f755e97d 52This clones the repository and makes a local copy in the F<perl-http>
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53directory.
54
55=head2 WRITE ACCESS TO THE REPOSITORY
56
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57If you are a committer, then you can fetch a copy of the repository
58that you can push back on with:
d7dd28b6 59
e0b2b458 60 % git clone ssh://perl5.git.perl.org/perl.git perl-ssh
d7dd28b6 61
8f718e95 62This clones the repository and makes a local copy in the F<perl-ssh>
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63directory.
64
c26da522 65If you cloned using the git protocol, which is faster than ssh, then
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66you will need to modify the URL for the origin remote to enable
67pushing. To do that edit F<.git/config> with L<git-config(1)> like
68this:
1a0f15d5 69
e0b2b458 70 % git config remote.origin.url ssh://perl5.git.perl.org/perl.git
d7dd28b6 71
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72You can also set up your user name and e-mail address. Most people do
73this once globally in their F<~/.gitconfig> by doing something like:
184487f0 74
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75 % git config --global user.name "Ævar Arnfjörð Bjarmason"
76 % git config --global user.email avarab@gmail.com
77
78However if you'd like to override that just for perl then execute then
79execute something like the following in F<perl-git>:
80
81 % git config user.email avar@cpan.org
184487f0 82
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83It is also possible to keep C<origin> as a git remote, and add a new
84remote for ssh access:
f6c12373 85
dc3c3040 86 % git remote add camel perl5.git.perl.org:/perl.git
f6c12373 87
6acba58e 88This allows you to update your local repository by pulling from
f755e97d 89C<origin>, which is faster and doesn't require you to authenticate, and
6acba58e 90to push your changes back with the C<camel> remote:
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91
92 % git fetch camel
93 % git push camel
94
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95The C<fetch> command just updates the C<camel> refs, as the objects
96themselves should have been fetched when pulling from C<origin>.
f6c12373 97
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98=head2 A NOTE ON CAMEL AND DROMEDARY
99
100The committers have SSH access to the two servers that serve
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101C<perl5.git.perl.org>. One is C<perl5.git.perl.org> itself (I<camel>),
102which is the 'master' repository. The second one is
103C<users.perl5.git.perl.org> (I<dromedary>), which can be used for
104general testing and development. Dromedary syncs the git tree from
105camel every few minutes, you should not push there. Both machines also
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106have a full CPAN mirror in /srv/CPAN, please use this. To share files
107with the general public, dromedary serves your ~/public_html/ as
333f8875 108C<http://users.perl5.git.perl.org/~yourlogin/>
b47aa495 109
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110These hosts have fairly strict firewalls to the outside. Outgoing, only
111rsync, ssh and git are allowed. For http and ftp, you can use
112http://webproxy:3128 as proxy. Incoming, the firewall tries to detect
113attacks and blocks IP addresses with suspicious activity. This
114sometimes (but very rarely) has false positives and you might get
115blocked. The quickest way to get unblocked is to notify the admins.
116
117These two boxes are owned, hosted, and operated by booking.com. You can
118reach the sysadmins in #p5p on irc.perl.org or via mail to
119C<perl5-porters@perl.org>
120
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121=head1 OVERVIEW OF THE REPOSITORY
122
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123Once you have changed into the repository directory, you can inspect
124it.
d7dd28b6 125
39219fd3 126After a clone the repository will contain a single local branch, which
50eca761 127will be the current branch as well, as indicated by the asterisk.
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128
129 % git branch
130 * blead
131
f755e97d 132Using the -a switch to C<branch> will also show the remote tracking
6acba58e 133branches in the repository:
39219fd3 134
d9847473 135 % git branch -a
09081495 136 * blead
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137 origin/HEAD
138 origin/blead
139 ...
140
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141The branches that begin with "origin" correspond to the "git remote"
142that you cloned from (which is named "origin"). Each branch on the
143remote will be exactly tracked by theses branches. You should NEVER do
144work on these remote tracking branches. You only ever do work in a
145local branch. Local branches can be configured to automerge (on pull)
146from a designated remote tracking branch. This is the case with the
147default branch C<blead> which will be configured to merge from the
148remote tracking branch C<origin/blead>.
39219fd3 149
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150You can see recent commits:
151
c2cf2042 152 % git log
d7dd28b6 153
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154And pull new changes from the repository, and update your local
155repository (must be clean first)
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156
157 % git pull
09081495 158
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159Assuming we are on the branch C<blead> immediately after a pull, this
160command would be more or less equivalent to:
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161
162 % git fetch
163 % git merge origin/blead
164
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165In fact if you want to update your local repository without touching
166your working directory you do:
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167
168 % git fetch
169
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170And if you want to update your remote-tracking branches for all defined
171remotes simultaneously you can do
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172
173 % git remote update
174
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175Neither of these last two commands will update your working directory,
176however both will update the remote-tracking branches in your
177repository.
39219fd3 178
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179To make a local branch of a remote branch:
180
181 % git checkout -b maint-5.10 origin/maint-5.10
182
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183To switch back to blead:
184
185 % git checkout blead
c2cf2042 186
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187=head2 FINDING OUT YOUR STATUS
188
189The most common git command you will use will probably be
190
191 % git status
192
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193This command will produce as output a description of the current state
194of the repository, including modified files and unignored untracked
195files, and in addition it will show things like what files have been
196staged for the next commit, and usually some useful information about
197how to change things. For instance the following:
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198
199 $ git status
200 # On branch blead
201 # Your branch is ahead of 'origin/blead' by 1 commit.
202 #
203 # Changes to be committed:
204 # (use "git reset HEAD <file>..." to unstage)
205 #
206 # modified: pod/perlrepository.pod
207 #
208 # Changed but not updated:
209 # (use "git add <file>..." to update what will be committed)
210 #
211 # modified: pod/perlrepository.pod
212 #
213 # Untracked files:
214 # (use "git add <file>..." to include in what will be committed)
215 #
216 # deliberate.untracked
217
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218This shows that there were changes to this document staged for commit,
219and that there were further changes in the working directory not yet
220staged. It also shows that there was an untracked file in the working
221directory, and as you can see shows how to change all of this. It also
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222shows that there is one commit on the working branch C<blead> which has
223not been pushed to the C<origin> remote yet. B<NOTE>: that this output
224is also what you see as a template if you do not provide a message to
225C<git commit>.
7f6effc7 226
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227Assuming that you'd like to commit all the changes you've just made as a
228a single atomic unit, run this command:
229
230 % git commit -a
231
232(That C<-a> tells git to add every file you've changed to this commit.
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233New files aren't automatically added to your commit when you use C<commit
234-a> If you want to add files or to commit some, but not all of your
235changes, have a look at the documentation for C<git add>.)
bdaf0bc6 236
e9360695 237Git will start up your favorite text editor, so that you can craft a
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238commit message for your change. See L</Commit message> below for more
239information about what makes a good commit message.
240
241Once you've finished writing your commit message and exited your editor,
242git will write your change to disk and tell you something like this:
7f6effc7 243
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244 Created commit daf8e63: explain git status and stuff about remotes
245 1 files changed, 83 insertions(+), 3 deletions(-)
246
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247
248If you re-run C<git status>, you should see something like this:
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249
250 % git status
251 # On branch blead
252 # Your branch is ahead of 'origin/blead' by 2 commits.
253 #
254 # Untracked files:
255 # (use "git add <file>..." to include in what will be committed)
256 #
257 # deliberate.untracked
258 nothing added to commit but untracked files present (use "git add" to track)
259
39219fd3 260
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261When in doubt, before you do anything else, check your status and read
262it carefully, many questions are answered directly by the git status
263output.
39219fd3 264
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265=head1 SUBMITTING A PATCH
266
267If you have a patch in mind for Perl, you should first get a copy of
268the repository:
269
270 % git clone git://perl5.git.perl.org/perl.git perl-git
271
272Then change into the directory:
273
274 % cd perl-git
275
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276Alternatively, if you already have a Perl repository, you should ensure
277that you're on the I<blead> branch, and your repository is up to date:
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278
279 % git checkout blead
280 % git pull
281
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282It's preferable to patch against the latest blead version, since this
283is where new development occurs for all changes other than critical bug
284fixes. Critical bug fix patches should be made against the relevant
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285maint branches, or should be submitted with a note indicating all the
286branches where the fix should be applied.
a44f43ac 287
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288Now that we have everything up to date, we need to create a temporary
289new branch for these changes and switch into it:
b1fccde5 290
a9b05323 291 % git checkout -b orange
23f8d33e 292
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293which is the short form of
294
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295 % git branch orange
296 % git checkout orange
297
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298Creating a topic branch makes it easier for the maintainers to rebase
299or merge back into the master blead for a more linear history. If you
300don't work on a topic branch the maintainer has to manually cherry
301pick your changes onto blead before they can be applied.
302
303That'll get you scolded on perl5-porters, so don't do that. Be
304Awesome.
305
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306Then make your changes. For example, if Leon Brocard changes his name
307to Orange Brocard, we should change his name in the AUTHORS file:
308
309 % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
310
311You can see what files are changed:
312
313 % git status
f755e97d 314 # On branch orange
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315 # Changes to be committed:
316 # (use "git reset HEAD <file>..." to unstage)
317 #
2699d634 318 # modified: AUTHORS
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319 #
320
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321And you can see the changes:
322
323 % git diff
324 diff --git a/AUTHORS b/AUTHORS
325 index 293dd70..722c93e 100644
326 --- a/AUTHORS
327 +++ b/AUTHORS
7df2e4bc 328 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
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329 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
330 Leif Huhn <leif@hale.dkstat.com>
331 Len Johnson <lenjay@ibm.net>
332 -Leon Brocard <acme@astray.com>
333 +Orange Brocard <acme@astray.com>
334 Les Peters <lpeters@aol.net>
335 Lesley Binks <lesley.binks@gmail.com>
336 Lincoln D. Stein <lstein@cshl.org>
337
338Now commit your change locally:
339
dc3c3040 340 % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
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341 Created commit 6196c1d: Rename Leon Brocard to Orange Brocard
342 1 files changed, 1 insertions(+), 1 deletions(-)
343
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344You can examine your last commit with:
345
346 % git show HEAD
347
348and if you are not happy with either the description or the patch
c26da522 349itself you can fix it up by editing the files once more and then issue:
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350
351 % git commit -a --amend
352
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353Now you should create a patch file for all your local changes:
354
2af192ee 355 % git format-patch origin
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356 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
357
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358You should now send an email to either perlbug@perl.org or
359perl5-porters@perl.org with a description of your changes, and include
360this patch file as an attachment. The perlbug address is preferred,
361but use perl5-porters for patches intended for discussion.
362
363See the next section for how to configure and use git to send these
364emails for you.
c2cf2042 365
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366If you want to delete your temporary branch, you may do so with:
367
368 % git checkout blead
369 % git branch -d orange
370 error: The branch 'orange' is not an ancestor of your current HEAD.
371 If you are sure you want to delete it, run 'git branch -D orange'.
372 % git branch -D orange
373 Deleted branch orange.
7df2e4bc 374
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375=head2 Using git to send patch emails
376
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377In your ~/git/perl repository, set the destination email to perl's bug
378tracker:
379
380 $ git config sendemail.to perlbug@perl.org
381
382Or maybe perl5-porters (discussed above):
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383
384 $ git config sendemail.to perl5-porters@perl.org
385
386Then you can use git directly to send your patch emails:
387
388 $ git send-email 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
389
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390You may need to set some configuration variables for your particular
391email service provider. For example, to set your global git config to
392send email via a gmail account:
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393
394 $ git config --global sendemail.smtpserver smtp.gmail.com
395 $ git config --global sendemail.smtpssl 1
396 $ git config --global sendemail.smtpuser YOURUSERNAME@gmail.com
397
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398With this configuration, you will be prompted for your gmail password
399when you run 'git send-email'. You can also configure
400C<sendemail.smtppass> with your password if you don't care about having
401your password in the .gitconfig file.
2d5f1d01 402
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403=head2 A note on derived files
404
405Be aware that many files in the distribution are derivative--avoid
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406patching them, because git won't see the changes to them, and the build
407process will overwrite them. Patch the originals instead. Most
408utilities (like perldoc) are in this category, i.e. patch
0be741b5 409F<utils/perldoc.PL> rather than F<utils/perldoc>. Similarly, don't create
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410patches for files under $src_root/ext from their copies found in
411$install_root/lib. If you are unsure about the proper location of a
412file that may have gotten copied while building the source
413distribution, consult the C<MANIFEST>.
a44f43ac 414
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415As a special case, several files are regenerated by 'make regen' if
416your patch alters C<embed.fnc>. These are needed for compilation, but
417are included in the distribution so that you can build perl without
418needing another perl to generate the files. You must test with these
419regenerated files, but it is preferred that you instead note that
420'make regen is needed' in both the email and the commit message, and
421submit your patch without them. If you're submitting a series of
422patches, it might be best to submit the regenerated changes
423immediately after the source-changes that caused them, so as to have
424as little effect as possible on the bisectability of your patchset.
425
6e2cec71 426=for XXX
a44f43ac 427
6e2cec71 428What should we recommend about binary files now? Do we need anything?
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429
430=head2 Getting your patch accepted
431
bdaf0bc6 432If you are submitting a code patch there are several things that
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433you need to do.
434
435=over 4
436
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437=item Commit message
438
439As you craft each patch you intend to submit to the Perl core, it's
440important to write a good commit message.
441
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442The first line of the commit message should be a short description and
443should skip the full stop. It should be no longer than the subject
444line of an E-Mail, 50 characters being a good rule of thumb.
445
446A lot of Git tools (Gitweb, GitHub, git log --pretty=oneline, ..) will
447only display the first line (cut off at 50 characters) when presenting
448commit summaries.
449
450The commit message should include description of the problem that the
451patch corrects or new functionality that the patch adds.
bdaf0bc6 452
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453As a general rule of thumb, your commit message should let a programmer
454with a reasonable familiarity with the Perl core quickly understand what
455you were trying to do, how you were trying to do it and why the change
456matters to Perl.
457
458=over 4
459
460=item What
461
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462Your commit message should describe what part of the Perl core you're
463changing and what you expect your patch to do.
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464
465=item Why
466
467Perhaps most importantly, your commit message should describe why the
468change you are making is important. When someone looks at your change
469in six months or six years, your intent should be clear. If you're
470deprecating a feature with the intent of later simplifying another bit
471of code, say so. If you're fixing a performance problem or adding a new
472feature to support some other bit of the core, mention that.
473
474=item How
475
476While it's not necessary for documentation changes, new tests or
477trivial patches, it's often worth explaining how your change works.
478Even if it's clear to you today, it may not be clear to a porter next
479month or next year.
480
481=back
482
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483A commit message isn't intended to take the place of comments in your
484code. Commit messages should describe the change you made, while code
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485comments should describe the current state of the code. If you've just
486implemented a new feature, complete with doc, tests and well-commented
487code, a brief commit message will often suffice. If, however, you've
488just changed a single character deep in the parser or lexer, you might
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489need to write a small novel to ensure that future readers understand
490what you did and why you did it.
491
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492=item Comments, Comments, Comments
493
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494Be sure to adequately comment your code. While commenting every line
495is unnecessary, anything that takes advantage of side effects of
a44f43ac 496operators, that creates changes that will be felt outside of the
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497function being patched, or that others may find confusing should be
498documented. If you are going to err, it is better to err on the side
499of adding too many comments than too few.
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500
501=item Style
502
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503In general, please follow the particular style of the code you are
504patching.
a44f43ac 505
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506In particular, follow these general guidelines for patching Perl
507sources:
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508
509 8-wide tabs (no exceptions!)
510 4-wide indents for code, 2-wide indents for nested CPP #defines
511 try hard not to exceed 79-columns
512 ANSI C prototypes
513 uncuddled elses and "K&R" style for indenting control constructs
514 no C++ style (//) comments
515 mark places that need to be revisited with XXX (and revisit often!)
516 opening brace lines up with "if" when conditional spans multiple
517 lines; should be at end-of-line otherwise
518 in function definitions, name starts in column 0 (return value is on
519 previous line)
520 single space after keywords that are followed by parens, no space
521 between function name and following paren
522 avoid assignments in conditionals, but if they're unavoidable, use
523 extra paren, e.g. "if (a && (b = c)) ..."
524 "return foo;" rather than "return(foo);"
525 "if (!foo) ..." rather than "if (foo == FALSE) ..." etc.
526
527=item Testsuite
528
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529If your patch changes code (rather than just changing documentation) you
530should also include one or more test cases which illustrate the bug you're
531fixing or validate the new functionality you're adding. In general,
532you should update an existing test file rather than create a new one.
533
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534Your testsuite additions should generally follow these guidelines
535(courtesy of Gurusamy Sarathy <gsar@activestate.com>):
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536
537 Know what you're testing. Read the docs, and the source.
538 Tend to fail, not succeed.
539 Interpret results strictly.
540 Use unrelated features (this will flush out bizarre interactions).
541 Use non-standard idioms (otherwise you are not testing TIMTOWTDI).
542 Avoid using hardcoded test numbers whenever possible (the
543 EXPECTED/GOT found in t/op/tie.t is much more maintainable,
544 and gives better failure reports).
545 Give meaningful error messages when a test fails.
546 Avoid using qx// and system() unless you are testing for them. If you
547 do use them, make sure that you cover _all_ perl platforms.
548 Unlink any temporary files you create.
549 Promote unforeseen warnings to errors with $SIG{__WARN__}.
550 Be sure to use the libraries and modules shipped with the version
551 being tested, not those that were already installed.
552 Add comments to the code explaining what you are testing for.
553 Make updating the '1..42' string unnecessary. Or make sure that
554 you update it.
555 Test _all_ behaviors of a given operator, library, or function:
556 - All optional arguments
557 - Return values in various contexts (boolean, scalar, list, lvalue)
558 - Use both global and lexical variables
559 - Don't forget the exceptional, pathological cases.
560
561=back
562
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563=head1 ACCEPTING A PATCH
564
565If you have received a patch file generated using the above section,
566you should try out the patch.
567
568First we need to create a temporary new branch for these changes and
569switch into it:
570
a9b05323 571 % git checkout -b experimental
7df2e4bc 572
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573Patches that were formatted by C<git format-patch> are applied with
574C<git am>:
7df2e4bc 575
2af192ee 576 % git am 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
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577 Applying Rename Leon Brocard to Orange Brocard
578
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579If just a raw diff is provided, it is also possible use this two-step
580process:
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581
582 % git apply bugfix.diff
dc3c3040 583 % git commit -a -m "Some fixing" --author="That Guy <that.guy@internets.com>"
09645c26 584
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585Now we can inspect the change:
586
dc3c3040 587 % git show HEAD
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588 commit b1b3dab48344cff6de4087efca3dbd63548ab5e2
589 Author: Leon Brocard <acme@astray.com>
590 Date: Fri Dec 19 17:02:59 2008 +0000
591
592 Rename Leon Brocard to Orange Brocard
7df2e4bc 593
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594 diff --git a/AUTHORS b/AUTHORS
595 index 293dd70..722c93e 100644
596 --- a/AUTHORS
597 +++ b/AUTHORS
598 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
599 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
600 Leif Huhn <leif@hale.dkstat.com>
601 Len Johnson <lenjay@ibm.net>
602 -Leon Brocard <acme@astray.com>
603 +Orange Brocard <acme@astray.com>
604 Les Peters <lpeters@aol.net>
605 Lesley Binks <lesley.binks@gmail.com>
606 Lincoln D. Stein <lstein@cshl.org>
607
608If you are a committer to Perl and you think the patch is good, you can
75fb7651 609then merge it into blead then push it out to the main repository:
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610
611 % git checkout blead
d9847473 612 % git merge experimental
75fb7651 613 % git push
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614
615If you want to delete your temporary branch, you may do so with:
616
617 % git checkout blead
618 % git branch -d experimental
619 error: The branch 'experimental' is not an ancestor of your current HEAD.
620 If you are sure you want to delete it, run 'git branch -D experimental'.
621 % git branch -D experimental
622 Deleted branch experimental.
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623
624=head1 CLEANING A WORKING DIRECTORY
625
6acba58e 626The command C<git clean> can with varying arguments be used as a
dc3c3040 627replacement for C<make clean>.
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628
629To reset your working directory to a pristine condition you can do:
630
e0b2b458 631 % git clean -dxf
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632
633However, be aware this will delete ALL untracked content. You can use
634
e0b2b458 635 % git clean -Xf
b0d36535 636
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637to remove all ignored untracked files, such as build and test
638byproduct, but leave any manually created files alone.
b0d36535 639
0549aefb 640If you only want to cancel some uncommitted edits, you can use C<git
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641checkout> and give it a list of files to be reverted, or C<git checkout
642-f> to revert them all.
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643
644If you want to cancel one or several commits, you can use C<git reset>.
645
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646=head1 BISECTING
647
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648C<git> provides a built-in way to determine, with a binary search in
649the history, which commit should be blamed for introducing a given bug.
d82a90c1 650
6acba58e 651Suppose that we have a script F<~/testcase.pl> that exits with C<0>
bdaf0bc6 652when some behaviour is correct, and with C<1> when it's faulty. You need
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653an helper script that automates building C<perl> and running the
654testcase:
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655
656 % cat ~/run
657 #!/bin/sh
658 git clean -dxf
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659
660 # If you get './makedepend: 1: Syntax error: Unterminated quoted
661 # string' when bisecting versions of perl older than 5.9.5 this hack
662 # will work around the bug in makedepend.SH which was fixed in
663 # version 96a8704c. Make sure to comment out `git co makedepend.SH'
664 # below too.
665 git show blead:makedepend.SH > makedepend.SH
666
d82a90c1 667 # If you can use ccache, add -Dcc=ccache\ gcc -Dld=gcc to the Configure line
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668 # if Encode is not needed for the test, you can speed up the bisect by
669 # excluding it from the runs with -Dnoextensions=Encode
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670 sh Configure -des -Dusedevel -Doptimize="-g"
671 test -f config.sh || exit 125
672 # Correct makefile for newer GNU gcc
673 perl -ni -we 'print unless /<(?:built-in|command)/' makefile x2p/makefile
674 # if you just need miniperl, replace test_prep with miniperl
d7923bfe 675 make test_prep
68814ba4 676 [ -x ./perl ] || exit 125
d82a90c1 677 ./perl -Ilib ~/testcase.pl
c0d1ef72 678 ret=$?
7930c68b 679 [ $ret -gt 127 ] && ret=127
a4583001 680 # git co makedepend.SH
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681 git clean -dxf
682 exit $ret
d82a90c1 683
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684This script may return C<125> to indicate that the corresponding commit
685should be skipped. Otherwise, it returns the status of
686F<~/testcase.pl>.
d82a90c1 687
bdaf0bc6 688You first enter in bisect mode with:
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689
690 % git bisect start
691
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692For example, if the bug is present on C<HEAD> but wasn't in 5.10.0,
693C<git> will learn about this when you enter:
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694
695 % git bisect bad
696 % git bisect good perl-5.10.0
697 Bisecting: 853 revisions left to test after this
698
6acba58e 699This results in checking out the median commit between C<HEAD> and
bdaf0bc6 700C<perl-5.10.0>. You can then run the bisecting process with:
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701
702 % git bisect run ~/run
703
704When the first bad commit is isolated, C<git bisect> will tell you so:
705
706 ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5 is first bad commit
707 commit ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5
708 Author: Dave Mitchell <davem@fdisolutions.com>
709 Date: Sat Feb 9 14:56:23 2008 +0000
710
9469eb4a 711 [perl #49472] Attributes + Unknown Error
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712 ...
713
714 bisect run success
715
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716You can peek into the bisecting process with C<git bisect log> and
717C<git bisect visualize>. C<git bisect reset> will get you out of bisect
718mode.
d82a90c1 719
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720Please note that the first C<good> state must be an ancestor of the
721first C<bad> state. If you want to search for the commit that I<solved>
722some bug, you have to negate your test case (i.e. exit with C<1> if OK
723and C<0> if not) and still mark the lower bound as C<good> and the
724upper as C<bad>. The "first bad commit" has then to be understood as
725the "first commit where the bug is solved".
d82a90c1 726
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727C<git help bisect> has much more information on how you can tweak your
728binary searches.
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730=head1 SUBMITTING A PATCH VIA GITHUB
731
732GitHub is a website that makes it easy to fork and publish projects
733with Git. First you should set up a GitHub account and log in.
734
735Perl's git repository is mirrored on GitHub at this page:
736
45b194c5 737 http://github.com/mirrors/perl/tree/blead
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738
739Visit the page and click the "fork" button. This clones the Perl git
740repository for you and provides you with "Your Clone URL" from which
741you should clone:
742
743 % git clone git@github.com:USERNAME/perl.git perl-github
744
bdaf0bc6 745The same patch as above, using github might look like this:
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746
747 % cd perl-github
edb9e29e 748 % git remote add upstream git://perl5.git.perl.org/perl.git
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749 % git pull upstream blead
750 % git checkout -b orange
751 % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
dc3c3040 752 % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
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753 % git push origin orange
754
755The orange branch has been pushed to GitHub, so you should now send an
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756email (see L</SUBMITTING A PATCH>) with a description of your changes
757and the following information:
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758
759 http://github.com/USERNAME/perl/tree/orange
760 git@github.com:USERNAME/perl.git branch orange
761
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762=head1 MERGING FROM A BRANCH VIA GITHUB
763
764If someone has provided a branch via GitHub and you are a committer,
5c9c28c6 765you should use the following in your perl-ssh directory:
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766
767 % git remote add dandv git://github.com/dandv/perl.git
fe442cc0 768 % git fetch dandv
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769
770Now you can see the differences between the branch and blead:
771
772 % git diff dandv/blead
773
774And you can see the commits:
775
776 % git log dandv/blead
777
778If you approve of a specific commit, you can cherry pick it:
779
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780 % git cherry-pick 3adac458cb1c1d41af47fc66e67b49c8dec2323f
781
782Or you could just merge the whole branch if you like it all:
783
784 % git merge dandv/blead
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785
786And then push back to the repository:
787
788 % git push
789
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790
791=head1 TOPIC BRANCHES AND REWRITING HISTORY
792
793Individual committers should create topic branches under
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794B<yourname>/B<some_descriptive_name>. Other committers should check
795with a topic branch's creator before making any change to it.
ce2a8773 796
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797The simplest way to create a remote topic branch that works on all
798versions of git is to push the current head as a new branch on the
799remote, then check it out locally:
800
801 $ branch="$yourname/$some_descriptive_name"
802 $ git push origin HEAD:$branch
803 $ git checkout -b $branch origin/$branch
804
805Users of git 1.7 or newer can do it in a more obvious manner:
806
807 $ branch="$yourname/$some_descriptive_name"
808 $ git checkout -b $branch
809 $ git push origin -u $branch
33e5002f 810
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811If you are not the creator of B<yourname>/B<some_descriptive_name>, you
812might sometimes find that the original author has edited the branch's
813history. There are lots of good reasons for this. Sometimes, an author
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814might simply be rebasing the branch onto a newer source point.
815Sometimes, an author might have found an error in an early commit which
816they wanted to fix before merging the branch to blead.
ce2a8773 817
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818Currently the master repository is configured to forbid
819non-fast-forward merges. This means that the branches within can not
820be rebased and pushed as a single step.
ce2a8773 821
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822The only way you will ever be allowed to rebase or modify the history
823of a pushed branch is to delete it and push it as a new branch under
824the same name. Please think carefully about doing this. It may be
825better to sequentially rename your branches so that it is easier for
826others working with you to cherry-pick their local changes onto the new
827version. (XXX: needs explanation).
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828
829If you want to rebase a personal topic branch, you will have to delete
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830your existing topic branch and push as a new version of it. You can do
831this via the following formula (see the explanation about C<refspec>'s
832in the git push documentation for details) after you have rebased your
833branch:
834
835 # first rebase
836 $ git checkout $user/$topic
837 $ git fetch
838 $ git rebase origin/blead
839
840 # then "delete-and-push"
841 $ git push origin :$user/$topic
842 $ git push origin $user/$topic
843
844B<NOTE:> it is forbidden at the repository level to delete any of the
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845"primary" branches. That is any branch matching
846C<m!^(blead|maint|perl)!>. Any attempt to do so will result in git
847producing an error like this:
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848
849 $ git push origin :blead
850 *** It is forbidden to delete blead/maint branches in this repository
851 error: hooks/update exited with error code 1
852 error: hook declined to update refs/heads/blead
333f8875 853 To ssh://perl5.git.perl.org/perl
2699d634 854 ! [remote rejected] blead (hook declined)
333f8875 855 error: failed to push some refs to 'ssh://perl5.git.perl.org/perl'
2699d634 856
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857As a matter of policy we do B<not> edit the history of the blead and
858maint-* branches. If a typo (or worse) sneaks into a commit to blead or
859maint-*, we'll fix it in another commit. The only types of updates
860allowed on these branches are "fast-forward's", where all history is
861preserved.
2699d634 862
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863Annotated tags in the canonical perl.git repository will never be
864deleted or modified. Think long and hard about whether you want to push
865a local tag to perl.git before doing so. (Pushing unannotated tags is
2699d634 866not allowed.)
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9469eb4a 868=head1 COMMITTING TO MAINTENANCE VERSIONS
9d68b7ed 869
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870Maintenance versions should only be altered to add critical bug fixes.
871
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872To commit to a maintenance version of perl, you need to create a local
873tracking branch:
874
875 % git checkout --track -b maint-5.005 origin/maint-5.005
876
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877This creates a local branch named C<maint-5.005>, which tracks the
878remote branch C<origin/maint-5.005>. Then you can pull, commit, merge
879and push as before.
b0d36535 880
f755e97d 881You can also cherry-pick commits from blead and another branch, by
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882using the C<git cherry-pick> command. It is recommended to use the
883B<-x> option to C<git cherry-pick> in order to record the SHA1 of the
884original commit in the new commit message.
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886=head1 GRAFTS
887
888The perl history contains one mistake which was not caught in the
ac036724 889conversion: a merge was recorded in the history between blead and
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890maint-5.10 where no merge actually occurred. Due to the nature of git,
891this is now impossible to fix in the public repository. You can remove
892this mis-merge locally by adding the following line to your
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893C<.git/info/grafts> file:
894
895 296f12bbbbaa06de9be9d09d3dcf8f4528898a49 434946e0cb7a32589ed92d18008aaa1d88515930
896
897It is particularly important to have this graft line if any bisecting
898is done in the area of the "merge" in question.
899
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900
901
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902=head1 SEE ALSO
903
904The git documentation, accessible via C<git help command>.
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