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1=head1 NAME
2
3perlrepository - Using the Perl source repository
4
5=head1 SYNOPSIS
6
7All of Perl's source code is kept centrally in a Git repository. The
8repository contains many Perl revisions from Perl 1 onwards and all
9the revisions from Perforce, the version control system we were using
10previously. This repository is accessible in different ways.
11
12The full repository takes up about 80MB of disk space. A check out of
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13the blead branch (that is, the master branch, which contains bleadperl,
14the development version of perl 5) takes up about 160MB of disk space
15(including the repository). A build of bleadperl takes up about 200MB
16(including the repository and the check out).
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17
18=head1 GETTING ACCESS TO THE REPOSITORY
19
20=head2 READ ACCESS VIA THE WEB
21
22You may access this over the web. This allows you to browse the tree,
23see recent commits, search for particular commits and more. You may
24access it at:
25
26 http://perl5.git.perl.org/perl.git
27
28=head2 READ ACCESS VIA GIT
29
30You will need a copy of Git for your computer. You can fetch a copy of
31the repository using the Git protocol (which uses port 9418):
32
3b8a5fb0 33 git clone git://perl5.git.perl.org/perl.git perl-git
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3b8a5fb0 35This clones the repository and makes a local copy in the 'perl-git'
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36directory.
37
38If your local network does not allow you to use port 9418, then you can
572f57ba 39fetch a copy of the repository over HTTP (this is slower):
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3b8a5fb0 41 git clone http://perl5.git.perl.org/perl.git perl-http
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3b8a5fb0 43This clones the repository and makes a local copy in the 'perl-http'
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44directory.
45
46=head2 WRITE ACCESS TO THE REPOSITORY
47
48If you are a committer, then you can fetch a copy of the repository that
49you can push back on with:
50
3b8a5fb0 51 git clone ssh://perl5.git.perl.org/gitroot/perl.git perl-ssh
d7dd28b6 52
3b8a5fb0 53This clones the repository and makes a local copy in the 'perl-ssh'
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54directory.
55
1a0f15d5 56If you clone using git, which is faster than ssh, then you will need to
d9847473 57modify your config in order to enable pushing. Edit F<.git/config> where
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58you will see something like:
59
60 [remote "origin"]
61 url = git://perl5.git.perl.org/perl.git
62
63change that to something like this:
64
65 [remote "origin"]
66 url = ssh://perl5.git.perl.org/gitroot/perl.git
67
68NOTE: there are symlinks set up so that the /gitroot is actually optional.
d7dd28b6 69
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70You can also set up your user name and e-mail address. For example
71
72 % git config user.name "Leon Brocard"
73 % git config user.email acme@astray.com
74
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75It is also possible to keep C<origin> as a git remote, and add a new remote for ssh access:
76
77 % git remote add camel user@camel:/gitroot/perl.git
78
79This allows you to update your local repository by pulling from C<origin>, which is faster and doesn't require you to authentify, and to push your changes back with the C<camel> remote:
80
81 % git fetch camel
82 % git push camel
83
84The C<fetch> command just updates the C<camel> refs, as the objects themselves should have been fetched when pulling from C<origin>.
85
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86=head1 OVERVIEW OF THE REPOSITORY
87
88Once you have changed into the repository directory, you can inspect it.
89
d7dd28b6 90
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91After a clone the repository will contain a single local branch, which
92will be the current branch as well, as indicated by the asterix.
93
94 % git branch
95 * blead
96
d9847473 97Using the -a switch to branch will also show the remote tracking branches in the
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98repository:
99
d9847473 100 % git branch -a
09081495 101 * blead
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102 origin/HEAD
103 origin/blead
104 ...
105
39219fd3 106The branches that begin with "origin" correspond to the "git remote" that
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107you cloned from (which is named "origin"). Each branch on the remote will
108be exactly tracked by theses branches. You should NEVER do work on these
109remote tracking branches. You only ever do work in a local branch. Local
110branches can be configured to automerge (on pull) from a designated remote
111tracking branch. This is the case with the default branch C<blead> which
112will be configured to merge from the remote tracking branch
113C<origin/blead>.
39219fd3 114
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115You can see recent commits:
116
c2cf2042 117 % git log
d7dd28b6 118
23f8d33e 119And pull new changes from the repository, and update your local repository
39219fd3 120(must be clean first)
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121
122 % git pull
09081495 123
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124Assuming we are on the branch C<blead> immediately after a pull, this command
125would be more or less equivalent to:
126
127 % git fetch
128 % git merge origin/blead
129
130In fact if you want to update your local repository without touching your working
131directory you do:
132
133 % git fetch
134
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135And if you want to update your remote-tracking branches for all defined remotes
136simultaneously you can do
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137
138 % git remote update
139
140Neither of these last two commands will update your working directory, however
d9847473 141both will update the remote-tracking branches in your repository.
39219fd3 142
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143To switch to another branch:
144
145 % git checkout origin/maint-5.8-dor
146
147To switch back to blead:
148
149 % git checkout blead
c2cf2042 150
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151=head2 FINDING OUT YOUR STATUS
152
153The most common git command you will use will probably be
154
155 % git status
156
23f8d33e 157This command will produce as output a description of the current state of the
39219fd3 158repository, including modified files and unignored untracked files, and in addition
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159it will show things like what files have been staged for the next commit,
160and usually some useful information about how to change things. For instance the
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161following:
162
163 $ git status
164 # On branch blead
165 # Your branch is ahead of 'origin/blead' by 1 commit.
166 #
167 # Changes to be committed:
168 # (use "git reset HEAD <file>..." to unstage)
169 #
170 # modified: pod/perlrepository.pod
171 #
172 # Changed but not updated:
173 # (use "git add <file>..." to update what will be committed)
174 #
175 # modified: pod/perlrepository.pod
176 #
177 # Untracked files:
178 # (use "git add <file>..." to include in what will be committed)
179 #
180 # deliberate.untracked
181
182This shows that there were changes to this document staged for commit, and
183that there were further changes in the working directory not yet staged. It
184also shows that there was an untracked file in the working directory, and as
185you can see shows how to change all of this. It also shows that there
186is one commit on the working branch C<blead> which has not been pushed to the
23f8d33e 187C<origin> remote yet. B<NOTE>: that this output is also what you see as a
d9847473 188template if you do not provide a message to C<git commit>.
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189
190Assuming we commit all the mentioned changes above:
191
192 % git commit -a -m'explain git status and stuff about remotes'
193 Created commit daf8e63: explain git status and stuff about remotes
194 1 files changed, 83 insertions(+), 3 deletions(-)
195
196We can re-run git status and see something like this:
197
198 % git status
199 # On branch blead
200 # Your branch is ahead of 'origin/blead' by 2 commits.
201 #
202 # Untracked files:
203 # (use "git add <file>..." to include in what will be committed)
204 #
205 # deliberate.untracked
206 nothing added to commit but untracked files present (use "git add" to track)
207
39219fd3 208
23f8d33e 209When in doubt, before you do anything else, check your status and read it
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210carefully, many questions are answered directly by the git status output.
211
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212=head1 SUBMITTING A PATCH
213
214If you have a patch in mind for Perl, you should first get a copy of
215the repository:
216
217 % git clone git://perl5.git.perl.org/perl.git perl-git
218
219Then change into the directory:
220
221 % cd perl-git
222
12322d22 223Alternatively, if you already have a Perl repository, you should
f5445761 224ensure that you're on the I<blead> branch, and your repository
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225is up to date:
226
227 % git checkout blead
228 % git pull
229
230Now that we have everything up to date, we need to create a temporary new
231branch for these changes and switch into it:
b1fccde5 232
a9b05323 233 % git checkout -b orange
23f8d33e 234
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235which is the short form of
236
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237 % git branch orange
238 % git checkout orange
239
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240Then make your changes. For example, if Leon Brocard changes his name
241to Orange Brocard, we should change his name in the AUTHORS file:
242
243 % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
244
245You can see what files are changed:
246
247 % git status
248 # On branch blead
249 # Changes to be committed:
250 # (use "git reset HEAD <file>..." to unstage)
251 #
252 # modified: AUTHORS
253 #
254
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255And you can see the changes:
256
257 % git diff
258 diff --git a/AUTHORS b/AUTHORS
259 index 293dd70..722c93e 100644
260 --- a/AUTHORS
261 +++ b/AUTHORS
7df2e4bc 262 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
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263 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
264 Leif Huhn <leif@hale.dkstat.com>
265 Len Johnson <lenjay@ibm.net>
266 -Leon Brocard <acme@astray.com>
267 +Orange Brocard <acme@astray.com>
268 Les Peters <lpeters@aol.net>
269 Lesley Binks <lesley.binks@gmail.com>
270 Lincoln D. Stein <lstein@cshl.org>
271
272Now commit your change locally:
273
274 % git add AUTHORS
275 % git commit -m 'Rename Leon Brocard to Orange Brocard'
276 Created commit 6196c1d: Rename Leon Brocard to Orange Brocard
277 1 files changed, 1 insertions(+), 1 deletions(-)
278
279Now you should create a patch file for all your local changes:
280
2af192ee 281 % git format-patch origin
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282 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
283
284You should now send an email to perl5-porters@perl.org with a
285description of your changes, and attach this patch file as an
286attachment.
287
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288If you want to delete your temporary branch, you may do so with:
289
290 % git checkout blead
291 % git branch -d orange
292 error: The branch 'orange' is not an ancestor of your current HEAD.
293 If you are sure you want to delete it, run 'git branch -D orange'.
294 % git branch -D orange
295 Deleted branch orange.
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296
297=head1 ACCEPTING A PATCH
298
299If you have received a patch file generated using the above section,
300you should try out the patch.
301
302First we need to create a temporary new branch for these changes and
303switch into it:
304
a9b05323 305 % git checkout -b experimental
7df2e4bc 306
09645c26 307Patches that were formatted by C<git format-patch> are applied with C<git am>:
7df2e4bc 308
2af192ee 309 % git am 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
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310 Applying Rename Leon Brocard to Orange Brocard
311
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312If just a raw diff is provided, it is also possible use this two-step process:
313
314 % git apply bugfix.diff
315 % git commit -am "Some fixing" --author="That Guy <that.guy@internets.com>"
316
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317Now we can inspect the change:
318
319 % git log
320 commit b1b3dab48344cff6de4087efca3dbd63548ab5e2
321 Author: Leon Brocard <acme@astray.com>
322 Date: Fri Dec 19 17:02:59 2008 +0000
323
324 Rename Leon Brocard to Orange Brocard
325 ...
326
327 % git diff blead
328 diff --git a/AUTHORS b/AUTHORS
329 index 293dd70..722c93e 100644
330 --- a/AUTHORS
331 +++ b/AUTHORS
332 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
333 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
334 Leif Huhn <leif@hale.dkstat.com>
335 Len Johnson <lenjay@ibm.net>
336 -Leon Brocard <acme@astray.com>
337 +Orange Brocard <acme@astray.com>
338 Les Peters <lpeters@aol.net>
339 Lesley Binks <lesley.binks@gmail.com>
340 Lincoln D. Stein <lstein@cshl.org>
341
342If you are a committer to Perl and you think the patch is good, you can
75fb7651 343then merge it into blead then push it out to the main repository:
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344
345 % git checkout blead
d9847473 346 % git merge experimental
75fb7651 347 % git push
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348
349If you want to delete your temporary branch, you may do so with:
350
351 % git checkout blead
352 % git branch -d experimental
353 error: The branch 'experimental' is not an ancestor of your current HEAD.
354 If you are sure you want to delete it, run 'git branch -D experimental'.
355 % git branch -D experimental
356 Deleted branch experimental.
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357
358=head1 CLEANING A WORKING DIRECTORY
359
360The command C<git clean> can with varying arguments be used as a replacement for make-clean.
361
362To reset your working directory to a pristine condition you can do:
363
364 git clean -dxf
365
366However, be aware this will delete ALL untracked content. You can use
367
368 git clean -Xf
369
370to remove all ignored untracked files, such as build and test byproduct, but leave any
371manually created files alone.
372
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373=head1 BISECTING
374
375C<git> provides a built-in way to determine, with a binary search in the history, which commit should be blamed for introducing a given bug.
376
377Suppose that we have a script F<~/testcase.pl> that exits with C<0> when some behaviour is correct, and with C<1> when it's faulty. We need an helper script that automates building C<perl> and running the testcase:
378
379 % cat ~/run
380 #!/bin/sh
381 git clean -dxf
382 # If you can use ccache, add -Dcc=ccache\ gcc -Dld=gcc to the Configure line
383 sh Configure -des -Dusedevel -Doptimize="-g" || exit 125
384 make || exit 125
385 ./perl -Ilib ~/testcase.pl
386
387This script may return C<125> to indicate that the corresponding commit should be skipped. Otherwise, it returns the status of F<~/testcase.pl>.
388
389We first enter in bisect mode with:
390
391 % git bisect start
392
393For example, if the bug is present on C<HEAD> but wasn't in 5.10.0, C<git> will learn about this when you enter:
394
395 % git bisect bad
396 % git bisect good perl-5.10.0
397 Bisecting: 853 revisions left to test after this
398
399This results in checking out the median commit between C<HEAD> and C<perl-5.10.0>. We can then run the bisecting process with:
400
401 % git bisect run ~/run
402
403When the first bad commit is isolated, C<git bisect> will tell you so:
404
405 ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5 is first bad commit
406 commit ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5
407 Author: Dave Mitchell <davem@fdisolutions.com>
408 Date: Sat Feb 9 14:56:23 2008 +0000
409
410 [perl #49472] Attributes + Unkown Error
411 ...
412
413 bisect run success
414
415You can peek into the bisecting process with C<git bisect log> and C<git bisect visualize>. C<git bisect reset> will get you out of bisect mode.
416
417Please note that the first C<good> state must be an ancestor of the first C<bad> state. If you want to search for the commit that I<solved> some bug, you have to negate your test case (i.e. exit with C<1> if OK and C<0> if not) and still mark the lower bound as C<good> and the upper as C<bad>. The "first bad commit" has then to be understood as the "first commit where the bug is solved".
418
419C<git help bisect> has much more information on how you can tweak your binary searches.
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420
421=head1 COMITTING TO MAINTENANCE VERSIONS
422
423To commit to a maintenance version of perl, you need to create a local
424tracking branch:
425
426 % git checkout --track -b maint-5.005 origin/maint-5.005
427
428This creates a local branch named maint-5.005, which tracks the remote
429branch origin/maint-5.005. Then you can pull, commit, merge and push
430as before.