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1 | Git User's Manual |
2 | _________________ | |
3 | ||
4 | This manual is designed to be readable by someone with basic unix | |
5 | commandline skills, but no previous knowledge of git. | |
6 | ||
7 | Comprehensive reference documentation is available through the man | |
8 | pages. For a command such as "git clone", just use | |
9 | ||
10 | ------------------------------------------------ | |
11 | $ man git-clone | |
12 | ------------------------------------------------ | |
13 | ||
14 | Repositories and Branches | |
15 | ========================= | |
16 | ||
17 | How to get a git repository | |
18 | --------------------------- | |
19 | ||
20 | It will be useful to have a git repository to experiment with as you | |
21 | read this manual. | |
22 | ||
23 | The best way to get one is by using the gitlink:git-clone[1] command | |
24 | to download a copy of an existing repository for a project that you | |
25 | are interested in. If you don't already have a project in mind, here | |
26 | are some interesting examples: | |
27 | ||
28 | ------------------------------------------------ | |
29 | # git itself (approx. 10MB download): | |
30 | $ git clone git://git.kernel.org/pub/scm/git/git.git | |
31 | # the linux kernel (approx. 150MB download): | |
32 | $ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git | |
33 | ------------------------------------------------ | |
34 | ||
35 | The initial clone may be time-consuming for a large project, but you | |
36 | will only need to clone once. | |
37 | ||
38 | The clone command creates a new directory named after the project | |
39 | ("git" or "linux-2.6" in the examples above). After you cd into this | |
40 | directory, you will see that it contains a copy of the project files, | |
41 | together with a special top-level directory named ".git", which | |
42 | contains all the information about the history of the project. | |
43 | ||
44 | In the following, examples will be taken from one of the two | |
45 | repositories above. | |
46 | ||
47 | How to check out a different version of a project | |
48 | ------------------------------------------------- | |
49 | ||
50 | Git is best thought of as a tool for storing the history of a | |
51 | collection of files. It stores the history as a compressed | |
52 | collection of interrelated snapshots (versions) of the project's | |
53 | contents. | |
54 | ||
55 | A single git repository may contain multiple branches. Each branch | |
56 | is a bookmark referencing a particular point in the project history. | |
57 | The gitlink:git-branch[1] command shows you the list of branches: | |
58 | ||
59 | ------------------------------------------------ | |
60 | $ git branch | |
61 | * master | |
62 | ------------------------------------------------ | |
63 | ||
64 | A freshly cloned repository contains a single branch, named "master", | |
65 | and the working directory contains the version of the project | |
66 | referred to by the master branch. | |
67 | ||
68 | Most projects also use tags. Tags, like branches, are references | |
69 | into the project's history, and can be listed using the | |
70 | gitlink:git-tag[1] command: | |
71 | ||
72 | ------------------------------------------------ | |
73 | $ git tag -l | |
74 | v2.6.11 | |
75 | v2.6.11-tree | |
76 | v2.6.12 | |
77 | v2.6.12-rc2 | |
78 | v2.6.12-rc3 | |
79 | v2.6.12-rc4 | |
80 | v2.6.12-rc5 | |
81 | v2.6.12-rc6 | |
82 | v2.6.13 | |
83 | ... | |
84 | ------------------------------------------------ | |
85 | ||
86 | Create a new branch pointing to one of these versions and check it | |
87 | out using gitlink:git-checkout[1]: | |
88 | ||
89 | ------------------------------------------------ | |
90 | $ git checkout -b new v2.6.13 | |
91 | ------------------------------------------------ | |
92 | ||
93 | The working directory then reflects the contents that the project had | |
94 | when it was tagged v2.6.13, and gitlink:git-branch[1] shows two | |
95 | branches, with an asterisk marking the currently checked-out branch: | |
96 | ||
97 | ------------------------------------------------ | |
98 | $ git branch | |
99 | master | |
100 | * new | |
101 | ------------------------------------------------ | |
102 | ||
103 | If you decide that you'd rather see version 2.6.17, you can modify | |
104 | the current branch to point at v2.6.17 instead, with | |
105 | ||
106 | ------------------------------------------------ | |
107 | $ git reset --hard v2.6.17 | |
108 | ------------------------------------------------ | |
109 | ||
110 | Note that if the current branch was your only reference to a | |
111 | particular point in history, then resetting that branch may leave you | |
112 | with no way to find the history it used to point to; so use this | |
113 | command carefully. | |
114 | ||
115 | Understanding History: Commits | |
116 | ------------------------------ | |
117 | ||
118 | Every change in the history of a project is represented by a commit. | |
119 | The gitlink:git-show[1] command shows the most recent commit on the | |
120 | current branch: | |
121 | ||
122 | ------------------------------------------------ | |
123 | $ git show | |
124 | commit 2b5f6dcce5bf94b9b119e9ed8d537098ec61c3d2 | |
125 | Author: Jamal Hadi Salim <hadi@cyberus.ca> | |
126 | Date: Sat Dec 2 22:22:25 2006 -0800 | |
127 | ||
128 | [XFRM]: Fix aevent structuring to be more complete. | |
129 | ||
130 | aevents can not uniquely identify an SA. We break the ABI with this | |
131 | patch, but consensus is that since it is not yet utilized by any | |
132 | (known) application then it is fine (better do it now than later). | |
133 | ||
134 | Signed-off-by: Jamal Hadi Salim <hadi@cyberus.ca> | |
135 | Signed-off-by: David S. Miller <davem@davemloft.net> | |
136 | ||
137 | diff --git a/Documentation/networking/xfrm_sync.txt b/Documentation/networking/xfrm_sync.txt | |
138 | index 8be626f..d7aac9d 100644 | |
139 | --- a/Documentation/networking/xfrm_sync.txt | |
140 | +++ b/Documentation/networking/xfrm_sync.txt | |
141 | @@ -47,10 +47,13 @@ aevent_id structure looks like: | |
142 | ||
143 | struct xfrm_aevent_id { | |
144 | struct xfrm_usersa_id sa_id; | |
145 | + xfrm_address_t saddr; | |
146 | __u32 flags; | |
147 | + __u32 reqid; | |
148 | }; | |
149 | ... | |
150 | ------------------------------------------------ | |
151 | ||
152 | As you can see, a commit shows who made the latest change, what they | |
153 | did, and why. | |
154 | ||
155 | Every commit has a 20-digit id, sometimes called the "SHA1 id", shown | |
156 | on the first line of the "git show" output. You can usually refer to | |
157 | a commit by a shorter name, such as a tag or a branch name, but this | |
158 | longer id can also be useful. In particular, it is a globally unique | |
159 | name for this commit: so if you tell somebody else the SHA1 id (for | |
160 | example in email), then you are guaranteed they will see the same | |
161 | commit in their repository that you do in yours. | |
162 | ||
163 | Understanding history: commits, parents, and reachability | |
164 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
165 | ||
166 | Every commit (except the very first commit in a project) also has a | |
167 | parent commit which shows what happened before this commit. | |
168 | Following the chain of parents will eventually take you back to the | |
169 | beginning of the project. | |
170 | ||
171 | However, the commits do not form a simple list; git allows lines of | |
172 | development to diverge and then reconverge, and the point where two | |
173 | lines of development reconverge is called a "merge". The commit | |
174 | representing a merge can therefore have more than one parent, with | |
175 | each parent representing the most recent commit on one of the lines | |
176 | of development leading to that point. | |
177 | ||
178 | The best way to see how this works is using the gitlink:gitk[1] | |
179 | command; running gitk now on a git repository and looking for merge | |
180 | commits will help understand how the git organizes history. | |
181 | ||
182 | In the following, we say that commit X is "reachable" from commit Y | |
183 | if commit X is an ancestor of commit Y. Equivalently, you could say | |
184 | that Y is a descendent of X, or that there is a chain of parents | |
185 | leading from commit Y to commit X. | |
186 | ||
187 | Undestanding history: History diagrams | |
188 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
189 | ||
190 | We will sometimes represent git history using diagrams like the one | |
191 | below. Commits are shown as "o", and the links between them with | |
192 | lines drawn with - / and \. Time goes left to right: | |
193 | ||
194 | o--o--o <-- Branch A | |
195 | / | |
196 | o--o--o <-- master | |
197 | \ | |
198 | o--o--o <-- Branch B | |
199 | ||
200 | If we need to talk about a particular commit, the character "o" may | |
201 | be replaced with another letter or number. | |
202 | ||
203 | Understanding history: What is a branch? | |
204 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
205 | ||
206 | Though we've been using the word "branch" to mean a kind of reference | |
207 | to a particular commit, the word branch is also commonly used to | |
208 | refer to the line of commits leading up to that point. In the | |
209 | example above, git may think of the branch named "A" as just a | |
210 | pointer to one particular commit, but we may refer informally to the | |
211 | line of three commits leading up to that point as all being part of | |
212 | "branch A". | |
213 | ||
214 | If we need to make it clear that we're just talking about the most | |
215 | recent commit on the branch, we may refer to that commit as the | |
216 | "head" of the branch. | |
217 | ||
218 | Manipulating branches | |
219 | --------------------- | |
220 | ||
221 | Creating, deleting, and modifying branches is quick and easy; here's | |
222 | a summary of the commands: | |
223 | ||
224 | git branch:: | |
225 | list all branches | |
226 | git branch <branch>:: | |
227 | create a new branch named <branch>, referencing the same | |
228 | point in history as the current branch | |
229 | git branch <branch> <start-point>:: | |
230 | create a new branch named <branch>, referencing | |
231 | <start-point>, which may be specified any way you like, | |
232 | including using a branch name or a tag name | |
233 | git branch -d <branch>:: | |
234 | delete the branch <branch>; if the branch you are deleting | |
235 | points to a commit which is not reachable from this branch, | |
236 | this command will fail with a warning. | |
237 | git branch -D <branch>:: | |
238 | even if the branch points to a commit not reachable | |
239 | from the current branch, you may know that that commit | |
240 | is still reachable from some other branch or tag. In that | |
241 | case it is safe to use this command to force git to delete | |
242 | the branch. | |
243 | git checkout <branch>:: | |
244 | make the current branch <branch>, updating the working | |
245 | directory to reflect the version referenced by <branch> | |
246 | git checkout -b <new> <start-point>:: | |
247 | create a new branch <new> referencing <start-point>, and | |
248 | check it out. | |
249 | ||
250 | It is also useful to know that the special symbol "HEAD" can always | |
251 | be used to refer to the current branch. | |
252 | ||
253 | Examining branches from a remote repository | |
254 | ------------------------------------------- | |
255 | ||
256 | The "master" branch that was created at the time you cloned is a copy | |
257 | of the HEAD in the repository that you cloned from. That repository | |
258 | may also have had other branches, though, and your local repository | |
259 | keeps branches which track each of those remote branches, which you | |
260 | can view using the "-r" option to gitlink:git-branch[1]: | |
261 | ||
262 | ------------------------------------------------ | |
263 | $ git branch -r | |
264 | origin/HEAD | |
265 | origin/html | |
266 | origin/maint | |
267 | origin/man | |
268 | origin/master | |
269 | origin/next | |
270 | origin/pu | |
271 | origin/todo | |
272 | ------------------------------------------------ | |
273 | ||
274 | You cannot check out these remote-tracking branches, but you can | |
275 | examine them on a branch of your own, just as you would a tag: | |
276 | ||
277 | ------------------------------------------------ | |
278 | $ git checkout -b my-todo-copy origin/todo | |
279 | ------------------------------------------------ | |
280 | ||
281 | Note that the name "origin" is just the name that git uses by default | |
282 | to refer to the repository that you cloned from. | |
283 | ||
284 | [[how-git-stores-references]] | |
285 | How git stores references | |
286 | ------------------------- | |
287 | ||
288 | Branches, remote-tracking branches, and tags are all references to | |
289 | commits. Git stores these references in the ".git" directory. Most | |
290 | of them are stored in .git/refs/: | |
291 | ||
292 | - branches are stored in .git/refs/heads | |
293 | - tags are stored in .git/refs/tags | |
294 | - remote-tracking branches for "origin" are stored in | |
295 | .git/refs/remotes/origin/ | |
296 | ||
297 | If you look at one of these files you will see that they usually | |
298 | contain just the SHA1 id of a commit: | |
299 | ||
300 | ------------------------------------------------ | |
301 | $ ls .git/refs/heads/ | |
302 | master | |
303 | $ cat .git/refs/heads/master | |
304 | c0f982dcf188d55db9d932a39d4ea7becaa55fed | |
305 | ------------------------------------------------ | |
306 | ||
307 | You can refer to a reference by its path relative to the .git | |
308 | directory. However, we've seen above that git will also accept | |
309 | shorter names; for example, "master" is an acceptable shortcut for | |
310 | "refs/heads/master", and "origin/master" is a shortcut for | |
311 | "refs/remotes/origin/master". | |
312 | ||
313 | As another useful shortcut, you can also refer to the "HEAD" of | |
314 | "origin" (or any other remote), using just the name of the remote. | |
315 | ||
316 | For the complete list of paths which git checks for references, and | |
317 | how it decides which to choose when there are multiple references | |
318 | with the same name, see the "SPECIFYING REVISIONS" section of | |
319 | gitlink:git-rev-parse[1]. | |
320 | ||
321 | [[Updating-a-repository-with-git-fetch]] | |
322 | Updating a repository with git fetch | |
323 | ------------------------------------ | |
324 | ||
325 | Eventually the developer cloned from will do additional work in her | |
326 | repository, creating new commits and advancing the branches to point | |
327 | at the new commits. | |
328 | ||
329 | The command "git fetch", with no arguments, will update all of the | |
330 | remote-tracking branches to the latest version found in her | |
331 | repository. It will not touch any of your own branches--not even the | |
332 | "master" branch that was created for you on clone. | |
333 | ||
334 | Fetching individual branches | |
335 | ---------------------------- | |
336 | ||
337 | You can also choose to update just one branch at a time: | |
338 | ||
339 | ------------------------------------------------- | |
340 | $ git fetch origin todo:refs/remotes/origin/todo | |
341 | ------------------------------------------------- | |
342 | ||
343 | The first argument, "origin", just tells git to fetch from the | |
344 | repository you originally cloned from. The second argument tells git | |
345 | to fetch the branch named "todo" from the remote repository, and to | |
346 | store it locally under the name refs/remotes/origin/todo; as we saw | |
347 | above, remote-tracking branches are stored under | |
348 | refs/remotes/<name-of-repository>/<name-of-branch>. | |
349 | ||
350 | You can also fetch branches from other repositories; so | |
351 | ||
352 | ------------------------------------------------- | |
353 | $ git fetch git://example.com/proj.git master:refs/remotes/example/master | |
354 | ------------------------------------------------- | |
355 | ||
356 | will create a new reference named "refs/remotes/example/master" and | |
357 | store in it the branch named "master" from the repository at the | |
358 | given URL. If you already have a branch named | |
359 | "refs/remotes/example/master", it will attempt to "fast-forward" to | |
360 | the commit given by example.com's master branch. So next we explain | |
361 | what a fast-forward is: | |
362 | ||
363 | [[fast-forwards]] | |
364 | Understanding git history: fast-forwards | |
365 | ---------------------------------------- | |
366 | ||
367 | In the previous example, when updating an existing branch, "git | |
368 | fetch" checks to make sure that the most recent commit on the remote | |
369 | branch is a descendant of the most recent commit on your copy of the | |
370 | branch before updating your copy of the branch to point at the new | |
371 | commit. Git calls this process a "fast forward". | |
372 | ||
373 | A fast forward looks something like this: | |
374 | ||
375 | o--o--o--o <-- old head of the branch | |
376 | \ | |
377 | o--o--o <-- new head of the branch | |
378 | ||
379 | ||
380 | In some cases it is possible that the new head will *not* actually be | |
381 | a descendant of the old head. For example, the developer may have | |
382 | realized she made a serious mistake, and decided to backtrack, | |
383 | resulting in a situation like: | |
384 | ||
385 | o--o--o--o--a--b <-- old head of the branch | |
386 | \ | |
387 | o--o--o <-- new head of the branch | |
388 | ||
389 | ||
390 | ||
391 | In this case, "git fetch" will fail, and print out a warning. | |
392 | ||
393 | In that case, you can still force git to update to the new head, as | |
394 | described in the following section. However, note that in the | |
395 | situation above this may mean losing the commits labeled "a" and "b", | |
396 | unless you've already created a reference of your own pointing to | |
397 | them. | |
398 | ||
399 | Forcing git fetch to do non-fast-forward updates | |
400 | ------------------------------------------------ | |
401 | ||
402 | If git fetch fails because the new head of a branch is not a | |
403 | descendant of the old head, you may force the update with: | |
404 | ||
405 | ------------------------------------------------- | |
406 | $ git fetch git://example.com/proj.git +master:refs/remotes/example/master | |
407 | ------------------------------------------------- | |
408 | ||
409 | Note the addition of the "+" sign. Be aware that commits which the | |
410 | old version of example/master pointed at may be lost, as we saw in | |
411 | the previous section. | |
412 | ||
413 | Configuring remote branches | |
414 | --------------------------- | |
415 | ||
416 | We saw above that "origin" is just a shortcut to refer to the | |
417 | repository which you originally cloned from. This information is | |
418 | stored in git configuration variables, which you can see using | |
419 | gitlink:git-repo-config[1]: | |
420 | ||
421 | ------------------------------------------------- | |
422 | $ git-repo-config -l | |
423 | core.repositoryformatversion=0 | |
424 | core.filemode=true | |
425 | core.logallrefupdates=true | |
426 | remote.origin.url=git://git.kernel.org/pub/scm/git/git.git | |
427 | remote.origin.fetch=+refs/heads/*:refs/remotes/origin/* | |
428 | branch.master.remote=origin | |
429 | branch.master.merge=refs/heads/master | |
430 | ------------------------------------------------- | |
431 | ||
432 | If there are other repositories that you also use frequently, you can | |
433 | create similar configuration options to save typing; for example, | |
434 | after | |
435 | ||
436 | ------------------------------------------------- | |
437 | $ git repo-config remote.example.url=git://example.com/proj.git | |
438 | ------------------------------------------------- | |
439 | ||
440 | then the following two commands will do the same thing: | |
441 | ||
442 | ------------------------------------------------- | |
443 | $ git fetch git://example.com/proj.git master:refs/remotes/example/master | |
444 | $ git fetch example master:refs/remotes/example/master | |
445 | ------------------------------------------------- | |
446 | ||
447 | Even better, if you add one more option: | |
448 | ||
449 | ------------------------------------------------- | |
450 | $ git repo-config remote.example.fetch=master:refs/remotes/example/master | |
451 | ------------------------------------------------- | |
452 | ||
453 | then the following commands will all do the same thing: | |
454 | ||
455 | ------------------------------------------------- | |
456 | $ git fetch git://example.com/proj.git master:ref/remotes/example/master | |
457 | $ git fetch example master:ref/remotes/example/master | |
458 | $ git fetch example example/master | |
459 | $ git fetch example | |
460 | ------------------------------------------------- | |
461 | ||
462 | You can also add a "+" to force the update each time: | |
463 | ||
464 | ------------------------------------------------- | |
465 | $ git repo-config +master:ref/remotes/example/master | |
466 | ------------------------------------------------- | |
467 | ||
468 | Don't do this unless you're sure you won't mind "git fetch" possibly | |
469 | throwing away commits on mybranch. | |
470 | ||
471 | Also note that all of the above configuration can be performed by | |
472 | directly editing the file .git/config instead of using | |
473 | gitlink:git-repo-config[1]. | |
474 | ||
475 | See gitlink:git-repo-config[1] for more details on the configuration | |
476 | options mentioned above. | |
477 | ||
478 | Exploring git history | |
479 | ===================== | |
480 | ||
481 | Git is best thought of as a tool for storing the history of a | |
482 | collection of files. It does this by storing compressed snapshots of | |
483 | the contents of a file heirarchy, together with "commits" which show | |
484 | the relationships between these snapshots. | |
485 | ||
486 | Git provides extremely flexible and fast tools for exploring the | |
487 | history of a project. | |
488 | ||
489 | We start with one specialized tool which is useful for finding the | |
490 | commit that introduced a bug into a project. | |
491 | ||
492 | How to use bisect to find a regression | |
493 | -------------------------------------- | |
494 | ||
495 | Suppose version 2.6.18 of your project worked, but the version at | |
496 | "master" crashes. Sometimes the best way to find the cause of such a | |
497 | regression is to perform a brute-force search through the project's | |
498 | history to find the particular commit that caused the problem. The | |
499 | gitlink:git-bisect[1] command can help you do this: | |
500 | ||
501 | ------------------------------------------------- | |
502 | $ git bisect start | |
503 | $ git bisect good v2.6.18 | |
504 | $ git bisect bad master | |
505 | Bisecting: 3537 revisions left to test after this | |
506 | [65934a9a028b88e83e2b0f8b36618fe503349f8e] BLOCK: Make USB storage depend on SCSI rather than selecting it [try #6] | |
507 | ------------------------------------------------- | |
508 | ||
509 | If you run "git branch" at this point, you'll see that git has | |
510 | temporarily moved you to a new branch named "bisect". This branch | |
511 | points to a commit (with commit id 65934...) that is reachable from | |
512 | v2.6.19 but not from v2.6.18. Compile and test it, and see whether | |
513 | it crashes. Assume it does crash. Then: | |
514 | ||
515 | ------------------------------------------------- | |
516 | $ git bisect bad | |
517 | Bisecting: 1769 revisions left to test after this | |
518 | [7eff82c8b1511017ae605f0c99ac275a7e21b867] i2c-core: Drop useless bitmaskings | |
519 | ------------------------------------------------- | |
520 | ||
521 | checks out an older version. Continue like this, telling git at each | |
522 | stage whether the version it gives you is good or bad, and notice | |
523 | that the number of revisions left to test is cut approximately in | |
524 | half each time. | |
525 | ||
526 | After about 13 tests (in this case), it will output the commit id of | |
527 | the guilty commit. You can then examine the commit with | |
528 | gitlink:git-show[1], find out who wrote it, and mail them your bug | |
529 | report with the commit id. Finally, run | |
530 | ||
531 | ------------------------------------------------- | |
532 | $ git bisect reset | |
533 | ------------------------------------------------- | |
534 | ||
535 | to return you to the branch you were on before and delete the | |
536 | temporary "bisect" branch. | |
537 | ||
538 | Note that the version which git-bisect checks out for you at each | |
539 | point is just a suggestion, and you're free to try a different | |
540 | version if you think it would be a good idea. For example, | |
541 | occasionally you may land on a commit that broke something unrelated; | |
542 | run | |
543 | ||
544 | ------------------------------------------------- | |
545 | $ git bisect-visualize | |
546 | ------------------------------------------------- | |
547 | ||
548 | which will run gitk and label the commit it chose with a marker that | |
549 | says "bisect". Chose a safe-looking commit nearby, note its commit | |
550 | id, and check it out with: | |
551 | ||
552 | ------------------------------------------------- | |
553 | $ git reset --hard fb47ddb2db... | |
554 | ------------------------------------------------- | |
555 | ||
556 | then test, run "bisect good" or "bisect bad" as appropriate, and | |
557 | continue. | |
558 | ||
559 | Naming commits | |
560 | -------------- | |
561 | ||
562 | We have seen several ways of naming commits already: | |
563 | ||
564 | - 20-digit SHA1 id | |
565 | - branch name: refers to the commit at the head of the given | |
566 | branch | |
567 | - tag name: refers to the commit pointed to by the given tag | |
568 | (we've seen branches and tags are special cases of | |
569 | <<how-git-stores-references,references>>). | |
570 | - HEAD: refers to the head of the current branch | |
571 | ||
572 | There are many more; see the "SPECIFYING REVISION" section of the | |
573 | gitlink:git-rev-list[1] man page for the complete list of ways to | |
574 | name revisions. Some examples: | |
575 | ||
576 | ------------------------------------------------- | |
577 | $ git show fb47ddb2 # the first few characters of the SHA1 id | |
578 | # are usually enough to specify it uniquely | |
579 | $ git show HEAD^ # the parent of the HEAD commit | |
580 | $ git show HEAD^^ # the grandparent | |
581 | $ git show HEAD~4 # the great-great-grandparent | |
582 | ------------------------------------------------- | |
583 | ||
584 | Recall that merge commits may have more than one parent; by default, | |
585 | ^ and ~ follow the first parent listed in the commit, but you can | |
586 | also choose: | |
587 | ||
588 | ------------------------------------------------- | |
589 | $ git show HEAD^1 # show the first parent of HEAD | |
590 | $ git show HEAD^2 # show the second parent of HEAD | |
591 | ------------------------------------------------- | |
592 | ||
593 | In addition to HEAD, there are several other special names for | |
594 | commits: | |
595 | ||
596 | Merges (to be discussed later), as well as operations such as | |
597 | git-reset, which change the currently checked-out commit, generally | |
598 | set ORIG_HEAD to the value HEAD had before the current operation. | |
599 | ||
600 | The git-fetch operation always stores the head of the last fetched | |
601 | branch in FETCH_HEAD. For example, if you run git fetch without | |
602 | specifying a local branch as the target of the operation | |
603 | ||
604 | ------------------------------------------------- | |
605 | $ git fetch git://example.com/proj.git theirbranch | |
606 | ------------------------------------------------- | |
607 | ||
608 | the fetched commits will still be available from FETCH_HEAD. | |
609 | ||
610 | When we discuss merges we'll also see the special name MERGE_HEAD, | |
611 | which refers to the other branch that we're merging in to the current | |
612 | branch. | |
613 | ||
614 | Creating tags | |
615 | ------------- | |
616 | ||
617 | We can also create a tag to refer to a particular commit; after | |
618 | running | |
619 | ||
620 | ------------------------------------------------- | |
621 | $ git-tag stable-1 1b2e1d63ff | |
622 | ------------------------------------------------- | |
623 | ||
624 | You can use stable-1 to refer to the commit 1b2e1d63ff. | |
625 | ||
626 | This creates a "lightweight" tag. If the tag is a tag you wish to | |
627 | share with others, and possibly sign cryptographically, then you | |
628 | should create a tag object instead; see the gitlink:git-tag[1] man | |
629 | page for details. | |
630 | ||
631 | Browsing revisions | |
632 | ------------------ | |
633 | ||
634 | The gitlink:git-log[1] command can show lists of commits. On its | |
635 | own, it shows all commits reachable from the parent commit; but you | |
636 | can also make more specific requests: | |
637 | ||
638 | ------------------------------------------------- | |
639 | $ git log v2.5.. # commits since (not reachable from) v2.5 | |
640 | $ git log test..master # commits reachable from master but not test | |
641 | $ git log master..test # ...reachable from test but not master | |
642 | $ git log master...test # ...reachable from either test or master, | |
643 | # but not both | |
644 | $ git log --since="2 weeks ago" # commits from the last 2 weeks | |
645 | $ git log Makefile # commits which modify Makefile | |
646 | $ git log fs/ # ... which modify any file under fs/ | |
647 | $ git log -S'foo()' # commits which add or remove any file data | |
648 | # matching the string 'foo()' | |
649 | ------------------------------------------------- | |
650 | ||
651 | And of course you can combine all of these; the following finds | |
652 | commits since v2.5 which touch the Makefile or any file under fs: | |
653 | ||
654 | ------------------------------------------------- | |
655 | $ git log v2.5.. Makefile fs/ | |
656 | ------------------------------------------------- | |
657 | ||
658 | You can also ask git log to show patches: | |
659 | ||
660 | ------------------------------------------------- | |
661 | $ git log -p | |
662 | ------------------------------------------------- | |
663 | ||
664 | See the "--pretty" option in the gitlink:git-log[1] man page for more | |
665 | display options. | |
666 | ||
667 | Note that git log starts with the most recent commit and works | |
668 | backwards through the parents; however, since git history can contain | |
669 | multiple independant lines of development, the particular order that | |
670 | commits are listed in may be somewhat arbitrary. | |
671 | ||
672 | Generating diffs | |
673 | ---------------- | |
674 | ||
675 | You can generate diffs between any two versions using | |
676 | gitlink:git-diff[1]: | |
677 | ||
678 | ------------------------------------------------- | |
679 | $ git diff master..test | |
680 | ------------------------------------------------- | |
681 | ||
682 | Sometimes what you want instead is a set of patches: | |
683 | ||
684 | ------------------------------------------------- | |
685 | $ git format-patch master..test | |
686 | ------------------------------------------------- | |
687 | ||
688 | will generate a file with a patch for each commit reachable from test | |
689 | but not from master. Note that if master also has commits which are | |
690 | not reachable from test, then the combined result of these patches | |
691 | will not be the same as the diff produced by the git-diff example. | |
692 | ||
693 | Viewing old file versions | |
694 | ------------------------- | |
695 | ||
696 | You can always view an old version of a file by just checking out the | |
697 | correct revision first. But sometimes it is more convenient to be | |
698 | able to view an old version of a single file without checking | |
699 | anything out; this command does that: | |
700 | ||
701 | ------------------------------------------------- | |
702 | $ git show v2.5:fs/locks.c | |
703 | ------------------------------------------------- | |
704 | ||
705 | Before the colon may be anything that names a commit, and after it | |
706 | may be any path to a file tracked by git. | |
707 | ||
708 | Developing with git | |
709 | =================== | |
710 | ||
711 | Telling git your name | |
712 | --------------------- | |
713 | ||
714 | Before creating any commits, you should introduce yourself to git. The | |
715 | easiest way to do so is: | |
716 | ||
717 | ------------------------------------------------ | |
718 | $ cat >~/.gitconfig <<\EOF | |
719 | [user] | |
720 | name = Your Name Comes Here | |
721 | email = you@yourdomain.example.com | |
722 | EOF | |
723 | ------------------------------------------------ | |
724 | ||
725 | ||
726 | Creating a new repository | |
727 | ------------------------- | |
728 | ||
729 | Creating a new repository from scratch is very easy: | |
730 | ||
731 | ------------------------------------------------- | |
732 | $ mkdir project | |
733 | $ cd project | |
734 | $ git init-db | |
735 | ------------------------------------------------- | |
736 | ||
737 | If you have some initial content (say, a tarball): | |
738 | ||
739 | ------------------------------------------------- | |
740 | $ tar -xzvf project.tar.gz | |
741 | $ cd project | |
742 | $ git init-db | |
743 | $ git add . # include everything below ./ in the first commit: | |
744 | $ git commit | |
745 | ------------------------------------------------- | |
746 | ||
747 | [[how-to-make-a-commit]] | |
748 | how to make a commit | |
749 | -------------------- | |
750 | ||
751 | Creating a new commit takes three steps: | |
752 | ||
753 | 1. Making some changes to the working directory using your | |
754 | favorite editor. | |
755 | 2. Telling git about your changes. | |
756 | 3. Creating the commit using the content you told git about | |
757 | in step 2. | |
758 | ||
759 | In practice, you can interleave and repeat steps 1 and 2 as many | |
760 | times as you want: in order to keep track of what you want committed | |
761 | at step 3, git maintains a snapshot of the tree's contents in a | |
762 | special staging area called "the index." | |
763 | ||
764 | By default, the content of the index is identical to that of the | |
765 | HEAD. The command "git diff --cached" shows the difference between | |
766 | HEAD and the index, so you should no output from that command. | |
767 | ||
768 | Modifying the index is easy: | |
769 | ||
770 | To update the index with the new contents of a modified file, use | |
771 | ||
772 | ------------------------------------------------- | |
773 | $ git add path/to/file | |
774 | ------------------------------------------------- | |
775 | ||
776 | To add the contents of a new file to the index, use | |
777 | ||
778 | ------------------------------------------------- | |
779 | $ git add path/to/file | |
780 | ------------------------------------------------- | |
781 | ||
782 | To remove a file from the index that you've removed from the working | |
783 | tree, | |
784 | ||
785 | ------------------------------------------------- | |
786 | $ git rm path/to/file | |
787 | ------------------------------------------------- | |
788 | ||
789 | After each step you can verify that | |
790 | ||
791 | ------------------------------------------------- | |
792 | $ git diff --cached | |
793 | ------------------------------------------------- | |
794 | ||
795 | always shows the difference between the HEAD and the index file--this | |
796 | is what you'd commit if you created the commit now--and that | |
797 | ||
798 | ------------------------------------------------- | |
799 | $ git diff | |
800 | ------------------------------------------------- | |
801 | ||
802 | shows the difference between the working tree and the index file. | |
803 | ||
804 | Note that "git add" always adds just the current contents of a file | |
805 | to the index; further changes to the same file will be ignored unless | |
806 | you run git-add on the file again. | |
807 | ||
808 | When you're ready, just run | |
809 | ||
810 | ------------------------------------------------- | |
811 | $ git commit | |
812 | ------------------------------------------------- | |
813 | ||
814 | and git will prompt you for a commit message and then create the new | |
815 | commmit. Check to make sure it looks like what you expected with | |
816 | ||
817 | ------------------------------------------------- | |
818 | $ git show | |
819 | ------------------------------------------------- | |
820 | ||
821 | As a special shortcut, | |
822 | ||
823 | ------------------------------------------------- | |
824 | $ git commit -a | |
825 | ------------------------------------------------- | |
826 | ||
827 | will update the index with any files that you've modified or removed | |
828 | and create a commit, all in one step. | |
829 | ||
830 | A number of commands are useful for keeping track of what you're | |
831 | about to commit: | |
832 | ||
833 | ------------------------------------------------- | |
834 | $ git diff --cached # difference between HEAD and the index; what | |
835 | # would be commited if you ran "commit" now. | |
836 | $ git diff # difference between the index file and your | |
837 | # working directory; changes that would not | |
838 | # be included if you ran "commit" now. | |
839 | $ git status # a brief per-file summary of the above. | |
840 | ------------------------------------------------- | |
841 | ||
842 | creating good commit messages | |
843 | ----------------------------- | |
844 | ||
845 | Though not required, it's a good idea to begin the commit message | |
846 | with a single short (less than 50 character) line summarizing the | |
847 | change, followed by a blank line and then a more thorough | |
848 | description. Tools that turn commits into email, for example, use | |
849 | the first line on the Subject line and the rest of the commit in the | |
850 | body. | |
851 | ||
852 | how to merge | |
853 | ------------ | |
854 | ||
855 | You can rejoin two diverging branches of development using | |
856 | gitlink:git-merge[1]: | |
857 | ||
858 | ------------------------------------------------- | |
859 | $ git merge branchname | |
860 | ------------------------------------------------- | |
861 | ||
862 | merges the development in the branch "branchname" into the current | |
863 | branch. If there are conflicts--for example, if the same file is | |
864 | modified in two different ways in the remote branch and the local | |
865 | branch--then you are warned; the output may look something like this: | |
866 | ||
867 | ------------------------------------------------- | |
868 | $ git pull . next | |
869 | Trying really trivial in-index merge... | |
870 | fatal: Merge requires file-level merging | |
871 | Nope. | |
872 | Merging HEAD with 77976da35a11db4580b80ae27e8d65caf5208086 | |
873 | Merging: | |
874 | 15e2162 world | |
875 | 77976da goodbye | |
876 | found 1 common ancestor(s): | |
877 | d122ed4 initial | |
878 | Auto-merging file.txt | |
879 | CONFLICT (content): Merge conflict in file.txt | |
880 | Automatic merge failed; fix conflicts and then commit the result. | |
881 | ------------------------------------------------- | |
882 | ||
883 | Conflict markers are left in the problematic files, and after | |
884 | you resolve the conflicts manually, you can update the index | |
885 | with the contents and run git commit, as you normally would when | |
886 | creating a new file. | |
887 | ||
888 | If you examine the resulting commit using gitk, you will see that it | |
889 | has two parents, one pointing to the top of the current branch, and | |
890 | one to the top of the other branch. | |
891 | ||
892 | In more detail: | |
893 | ||
894 | [[resolving-a-merge]] | |
895 | Resolving a merge | |
896 | ----------------- | |
897 | ||
898 | When a merge isn't resolved automatically, git leaves the index and | |
899 | the working tree in a special state that gives you all the | |
900 | information you need to help resolve the merge. | |
901 | ||
902 | Files with conflicts are marked specially in the index, so until you | |
903 | resolve the problem and update the index, git commit will fail: | |
904 | ||
905 | ------------------------------------------------- | |
906 | $ git commit | |
907 | file.txt: needs merge | |
908 | ------------------------------------------------- | |
909 | ||
910 | Also, git status will list those files as "unmerged". | |
911 | ||
912 | All of the changes that git was able to merge automatically are | |
913 | already added to the index file, so gitlink:git-diff[1] shows only | |
914 | the conflicts. Also, it uses a somewhat unusual syntax: | |
915 | ||
916 | ------------------------------------------------- | |
917 | $ git diff | |
918 | diff --cc file.txt | |
919 | index 802992c,2b60207..0000000 | |
920 | --- a/file.txt | |
921 | +++ b/file.txt | |
922 | @@@ -1,1 -1,1 +1,5 @@@ | |
923 | ++<<<<<<< HEAD:file.txt | |
924 | +Hello world | |
925 | ++======= | |
926 | + Goodbye | |
927 | ++>>>>>>> 77976da35a11db4580b80ae27e8d65caf5208086:file.txt | |
928 | ------------------------------------------------- | |
929 | ||
930 | Recall that the commit which will be commited after we resolve this | |
931 | conflict will have two parents instead of the usual one: one parent | |
932 | will be HEAD, the tip of the current branch; the other will be the | |
933 | tip of the other branch, which is stored temporarily in MERGE_HEAD. | |
934 | ||
935 | The diff above shows the differences between the working-tree version | |
936 | of file.txt and two previous version: one version from HEAD, and one | |
937 | from MERGE_HEAD. So instead of preceding each line by a single "+" | |
938 | or "-", it now uses two columns: the first column is used for | |
939 | differences between the first parent and the working directory copy, | |
940 | and the second for differences between the second parent and the | |
941 | working directory copy. Thus after resolving the conflict in the | |
942 | obvious way, the diff will look like: | |
943 | ||
944 | ------------------------------------------------- | |
945 | $ git diff | |
946 | diff --cc file.txt | |
947 | index 802992c,2b60207..0000000 | |
948 | --- a/file.txt | |
949 | +++ b/file.txt | |
950 | @@@ -1,1 -1,1 +1,1 @@@ | |
951 | - Hello world | |
952 | -Goodbye | |
953 | ++Goodbye world | |
954 | ------------------------------------------------- | |
955 | ||
956 | This shows that our resolved version deleted "Hello world" from the | |
957 | first parent, deleted "Goodbye" from the second parent, and added | |
958 | "Goodbye world", which was previously absent from both. | |
959 | ||
960 | The gitlink:git-log[1] command also provides special help for merges: | |
961 | ||
962 | ------------------------------------------------- | |
963 | $ git log --merge | |
964 | ------------------------------------------------- | |
965 | ||
966 | This will list all commits which exist only on HEAD or on MERGE_HEAD, | |
967 | and which touch an unmerged file. | |
968 | ||
969 | We can now add the resolved version to the index and commit: | |
970 | ||
971 | ------------------------------------------------- | |
972 | $ git add file.txt | |
973 | $ git commit | |
974 | ------------------------------------------------- | |
975 | ||
976 | Note that the commit message will already be filled in for you with | |
977 | some information about the merge. Normally you can just use this | |
978 | default message unchanged, but you may add additional commentary of | |
979 | your own if desired. | |
980 | ||
981 | [[undoing-a-merge]] | |
982 | undoing a merge | |
983 | --------------- | |
984 | ||
985 | If you get stuck and decide to just give up and throw the whole mess | |
986 | away, you can always return to the pre-merge state with | |
987 | ||
988 | ------------------------------------------------- | |
989 | $ git reset --hard HEAD | |
990 | ------------------------------------------------- | |
991 | ||
992 | Or, if you've already commited the merge that you want to throw away, | |
993 | ||
994 | ------------------------------------------------- | |
995 | $ git reset --hard HEAD^ | |
996 | ------------------------------------------------- | |
997 | ||
998 | However, this last command can be dangerous in some cases--never | |
999 | throw away a commit you have already committed if that commit may | |
1000 | itself have been merged into another branch, as doing so may confuse | |
1001 | further merges. | |
1002 | ||
1003 | Fast-forward merges | |
1004 | ------------------- | |
1005 | ||
1006 | There is one special case not mentioned above, which is treated | |
1007 | differently. Normally, a merge results in a merge commit, with two | |
1008 | parents, one pointing at each of the two lines of development that | |
1009 | were merged. | |
1010 | ||
1011 | However, if one of the two lines of development is completely | |
1012 | contained within the other--so every commit present in the one is | |
1013 | already contained in the other--then git just performs a | |
1014 | <<fast-forwards,fast forward>>; the head of the current branch is | |
1015 | moved forward to point at the head of the merged-in branch, without | |
1016 | any new commits being created. | |
1017 | ||
1018 | Ensuring good performance | |
1019 | ------------------------- | |
1020 | ||
1021 | On large repositories, git depends on compression to keep the history | |
1022 | information from taking up to much space on disk or in memory. | |
1023 | ||
1024 | This compression is not performed automatically. Therefore you | |
1025 | should occasionally run | |
1026 | ||
1027 | ------------------------------------------------- | |
1028 | $ git gc | |
1029 | ------------------------------------------------- | |
1030 | ||
1031 | to recompress the archive and to prune any commits which are no | |
1032 | longer referred to anywhere. This can be very time-consuming, and | |
1033 | you should not modify the repository while it is working, so you | |
1034 | should run it while you are not working. | |
1035 | ||
1036 | Sharing development with others | |
1037 | ------------------------------- | |
1038 | ||
1039 | [[getting-updates-with-git-pull]] | |
1040 | Getting updates with git pull | |
1041 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
1042 | ||
1043 | After you clone a repository and make a few changes of your own, you | |
1044 | may wish to check the original repository for updates and merge them | |
1045 | into your own work. | |
1046 | ||
1047 | We have already seen <<Updating-a-repository-with-git-fetch,how to | |
1048 | keep remote tracking branches up to date>> with gitlink:git-fetch[1], | |
1049 | and how to merge two branches. So you can merge in changes from the | |
1050 | original repository's master branch with: | |
1051 | ||
1052 | ------------------------------------------------- | |
1053 | $ git fetch | |
1054 | $ git merge origin/master | |
1055 | ------------------------------------------------- | |
1056 | ||
1057 | However, the gitlink:git-pull[1] command provides a way to do this in | |
1058 | one step: | |
1059 | ||
1060 | ------------------------------------------------- | |
1061 | $ git pull origin master | |
1062 | ------------------------------------------------- | |
1063 | ||
1064 | In fact, "origin" is normally the default repository to pull from, | |
1065 | and the default branch is normally the HEAD of the remote repository, | |
1066 | so often you can accomplish the above with just | |
1067 | ||
1068 | ------------------------------------------------- | |
1069 | $ git pull | |
1070 | ------------------------------------------------- | |
1071 | ||
1072 | See the descriptions of the branch.<name>.remote and | |
1073 | branch.<name>.merge options in gitlink:git-repo-config[1] to learn | |
1074 | how to control these defaults depending on the current branch. | |
1075 | ||
1076 | In addition to saving you keystrokes, "git pull" also helps you by | |
1077 | producing a default commit message documenting the branch and | |
1078 | repository that you pulled from. | |
1079 | ||
1080 | (But note that no such commit will be created in the case of a | |
1081 | <<fast-forwards,fast forward>>; instead, your branch will just be | |
1082 | updated to point to the latest commit from the upstream branch). | |
1083 | ||
1084 | Submitting patches to a project | |
1085 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
1086 | ||
1087 | If you just have a few changes, the simplest way to submit them may | |
1088 | just be to send them as patches in email: | |
1089 | ||
1090 | First, use gitlink:git-format-patches[1]; for example: | |
1091 | ||
1092 | ------------------------------------------------- | |
1093 | $ git format-patches origin | |
1094 | ------------------------------------------------- | |
1095 | ||
1096 | will produce a numbered series of files in the current directory, one | |
1097 | for each patch in the current branch but not in origin/HEAD. | |
1098 | ||
1099 | You can then import these into your mail client and send them by | |
1100 | hand. However, if you have a lot to send at once, you may prefer to | |
1101 | use the gitlink:git-send-email[1] script to automate the process. | |
1102 | Consult the mailing list for your project first to determine how they | |
1103 | prefer such patches be handled. | |
1104 | ||
1105 | Importing patches to a project | |
1106 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
1107 | ||
1108 | Git also provides a tool called gitlink:git-am[1] (am stands for | |
1109 | "apply mailbox"), for importing such an emailed series of patches. | |
1110 | Just save all of the patch-containing messages, in order, into a | |
1111 | single mailbox file, say "patches.mbox", then run | |
1112 | ||
1113 | ------------------------------------------------- | |
1114 | $ git am patches.mbox | |
1115 | ------------------------------------------------- | |
1116 | ||
1117 | Git will apply each patch in order; if any conflicts are found, it | |
1118 | will stop, and you can fix the conflicts as described in | |
1119 | "<<resolving-a-merge,Resolving a merge>>". Once the index is updated | |
1120 | with the results of the conflict resolution, instead of creating a | |
1121 | new commit, just run | |
1122 | ||
1123 | ------------------------------------------------- | |
1124 | $ git am --resolved | |
1125 | ------------------------------------------------- | |
1126 | ||
1127 | and git will create the commit for you and continue applying the | |
1128 | remaining patches from the mailbox. | |
1129 | ||
1130 | The final result will be a series of commits, one for each patch in | |
1131 | the original mailbox, with authorship and commit log message each | |
1132 | taken from the message containing each patch. | |
1133 | ||
1134 | [[setting-up-a-public-repository]] | |
1135 | Setting up a public repository | |
1136 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
1137 | ||
1138 | Another way to submit changes to a project is to simply tell the | |
1139 | maintainer of that project to pull from your repository, exactly as | |
1140 | you did in the section "<<getting-updates-with-git-pull, Getting | |
1141 | updates with git pull>>". | |
1142 | ||
1143 | If you and maintainer both have accounts on the same machine, then | |
1144 | then you can just pull changes from each other's repositories | |
1145 | directly; note that all of the command (gitlink:git-clone[1], | |
1146 | git-fetch[1], git-pull[1], etc.) which accept a URL as an argument | |
1147 | will also accept a local file patch; so, for example, you can | |
1148 | use | |
1149 | ||
1150 | ------------------------------------------------- | |
1151 | $ git clone /path/to/repository | |
1152 | $ git pull /path/to/other/repository | |
1153 | ------------------------------------------------- | |
1154 | ||
1155 | If this sort of setup is inconvenient or impossible, another (more | |
1156 | common) option is to set up a public repository on a public server. | |
1157 | This also allows you to cleanly separate private work in progress | |
1158 | from publicly visible work. | |
1159 | ||
1160 | You will continue to do your day-to-day work in your personal | |
1161 | repository, but periodically "push" changes from your personal | |
1162 | repository into your public repository, allowing other developers to | |
1163 | pull from that repository. So the flow of changes, in a situation | |
1164 | where there is one other developer with a public repository, looks | |
1165 | like this: | |
1166 | ||
1167 | you push | |
1168 | your personal repo ------------------> your public repo | |
1169 | ^ | | |
1170 | | | | |
1171 | | you pull | they pull | |
1172 | | | | |
1173 | | | | |
1174 | | they push V | |
1175 | their public repo <------------------- their repo | |
1176 | ||
1177 | Now, assume your personal repository is in the directory ~/proj. We | |
1178 | first create a new clone of the repository: | |
1179 | ||
1180 | ------------------------------------------------- | |
1181 | $ git clone --bare proj-clone.git | |
1182 | ------------------------------------------------- | |
1183 | ||
1184 | The resulting directory proj-clone.git will contains a "bare" git | |
1185 | repository--it is just the contents of the ".git" directory, without | |
1186 | a checked-out copy of a working directory. | |
1187 | ||
1188 | Next, copy proj-clone.git to the server where you plan to host the | |
1189 | public repository. You can use scp, rsync, or whatever is most | |
1190 | convenient. | |
1191 | ||
1192 | If somebody else maintains the public server, they may already have | |
1193 | set up a git service for you, and you may skip to the section | |
1194 | "<<pushing-changes-to-a-public-repository,Pushing changes to a public | |
1195 | repository>>", below. | |
1196 | ||
1197 | Otherwise, the following sections explain how to export your newly | |
1198 | created public repository: | |
1199 | ||
1200 | [[exporting-via-http]] | |
1201 | Exporting a git repository via http | |
1202 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
1203 | ||
1204 | The git protocol gives better performance and reliability, but on a | |
1205 | host with a web server set up, http exports may be simpler to set up. | |
1206 | ||
1207 | All you need to do is place the newly created bare git repository in | |
1208 | a directory that is exported by the web server, and make some | |
1209 | adjustments to give web clients some extra information they need: | |
1210 | ||
1211 | ------------------------------------------------- | |
1212 | $ mv proj.git /home/you/public_html/proj.git | |
1213 | $ cd proj.git | |
1214 | $ git update-server-info | |
1215 | $ chmod a+x hooks/post-update | |
1216 | ------------------------------------------------- | |
1217 | ||
1218 | (For an explanation of the last two lines, see | |
1219 | gitlink:git-update-server-info[1], and the documentation | |
1220 | link:hooks.txt[Hooks used by git].) | |
1221 | ||
1222 | Advertise the url of proj.git. Anybody else should then be able to | |
1223 | clone or pull from that url, for example with a commandline like: | |
1224 | ||
1225 | ------------------------------------------------- | |
1226 | $ git clone http://yourserver.com/~you/proj.git | |
1227 | ------------------------------------------------- | |
1228 | ||
1229 | (See also | |
1230 | link:howto/setup-git-server-over-http.txt[setup-git-server-over-http] | |
1231 | for a slightly more sophisticated setup using WebDAV which also | |
1232 | allows pushing over http.) | |
1233 | ||
1234 | [[exporting-via-git]] | |
1235 | Exporting a git repository via the git protocol | |
1236 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
1237 | ||
1238 | This is the preferred method. | |
1239 | ||
1240 | For now, we refer you to the gitlink:git-daemon[1] man page for | |
1241 | instructions. (See especially the examples section.) | |
1242 | ||
1243 | [[pushing-changes-to-a-public-repository]] | |
1244 | Pushing changes to a public repository | |
1245 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
1246 | ||
1247 | Note that the two techniques outline above (exporting via | |
1248 | <<exporting-via-http,http>> or <<exporting-via-git,git>>) allow other | |
1249 | maintainers to fetch your latest changes, but they do not allow write | |
1250 | access, which you will need to update the public repository with the | |
1251 | latest changes created in your private repository. | |
1252 | ||
1253 | The simplest way to do this is using gitlink:git-push[1] and ssh; to | |
1254 | update the remote branch named "master" with the latest state of your | |
1255 | branch named "master", run | |
1256 | ||
1257 | ------------------------------------------------- | |
1258 | $ git push ssh://yourserver.com/~you/proj.git master:master | |
1259 | ------------------------------------------------- | |
1260 | ||
1261 | or just | |
1262 | ||
1263 | ------------------------------------------------- | |
1264 | $ git push ssh://yourserver.com/~you/proj.git master | |
1265 | ------------------------------------------------- | |
1266 | ||
1267 | As with git-fetch, git-push will complain if this does not result in | |
1268 | a <<fast-forwards,fast forward>>. Normally this is a sign of | |
1269 | something wrong. However, if you are sure you know what you're | |
1270 | doing, you may force git-push to perform the update anyway by | |
1271 | proceeding the branch name by a plus sign: | |
1272 | ||
1273 | ------------------------------------------------- | |
1274 | $ git push ssh://yourserver.com/~you/proj.git +master | |
1275 | ------------------------------------------------- | |
1276 | ||
1277 | As with git-fetch, you may also set up configuration options to | |
1278 | save typing; so, for example, after | |
1279 | ||
1280 | ------------------------------------------------- | |
1281 | $ cat >.git/config <<EOF | |
1282 | [remote "public-repo"] | |
1283 | url = ssh://yourserver.com/~you/proj.git | |
1284 | EOF | |
1285 | ------------------------------------------------- | |
1286 | ||
1287 | you should be able to perform the above push with just | |
1288 | ||
1289 | ------------------------------------------------- | |
1290 | $ git push public-repo master | |
1291 | ------------------------------------------------- | |
1292 | ||
1293 | See the explanations of the remote.<name>.url, branch.<name>.remote, | |
1294 | and remote.<name>.push options in gitlink:git-repo-config[1] for | |
1295 | details. | |
1296 | ||
1297 | Setting up a shared repository | |
1298 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
1299 | ||
1300 | Another way to collaborate is by using a model similar to that | |
1301 | commonly used in CVS, where several developers with special rights | |
1302 | all push to and pull from a single shared repository. See | |
1303 | link:cvs-migration.txt[git for CVS users] for instructions on how to | |
1304 | set this up. | |
1305 | ||
1306 | Fixing mistakes | |
1307 | --------------- | |
1308 | ||
1309 | If you've messed up the working tree, but haven't yet committed your | |
1310 | mistake, you can return the entire working tree to the last committed | |
1311 | state with | |
1312 | ||
1313 | ------------------------------------------------- | |
1314 | $ git reset --hard HEAD | |
1315 | ------------------------------------------------- | |
1316 | ||
1317 | If you make a commit that you later wish you hadn't, there are two | |
1318 | fundamentally different ways to fix the problem: | |
1319 | ||
1320 | 1. You can create a new commit that undoes whatever was done | |
1321 | by the previous commit. This is the correct thing if your | |
1322 | mistake has already been made public. | |
1323 | ||
1324 | 2. You can go back and modify the old commit. You should | |
1325 | never do this if you have already made the history public; | |
1326 | git does not normally expect the "history" of a project to | |
1327 | change, and cannot correctly perform repeated merges from | |
1328 | a branch that has had its history changed. | |
1329 | ||
1330 | Fixing a mistake with a new commit | |
1331 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
1332 | ||
1333 | Creating a new commit that reverts an earlier change is very easy; | |
1334 | just pass the gitlink:git-revert[1] command a reference to the bad | |
1335 | commit; for example, to revert the most recent commit: | |
1336 | ||
1337 | ------------------------------------------------- | |
1338 | $ git revert HEAD | |
1339 | ------------------------------------------------- | |
1340 | ||
1341 | This will create a new commit which undoes the change in HEAD. You | |
1342 | will be given a chance to edit the commit message for the new commit. | |
1343 | ||
1344 | You can also revert an earlier change, for example, the next-to-last: | |
1345 | ||
1346 | ------------------------------------------------- | |
1347 | $ git revert HEAD^ | |
1348 | ------------------------------------------------- | |
1349 | ||
1350 | In this case git will attempt to undo the old change while leaving | |
1351 | intact any changes made since then. If more recent changes overlap | |
1352 | with the changes to be reverted, then you will be asked to fix | |
1353 | conflicts manually, just as in the case of <<resolving-a-merge, | |
1354 | resolving a merge>>. | |
1355 | ||
1356 | Fixing a mistake by editing history | |
1357 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
1358 | ||
1359 | If the problematic commit is the most recent commit, and you have not | |
1360 | yet made that commit public, then you may just | |
1361 | <<undoing-a-merge,destroy it using git-reset>>. | |
1362 | ||
1363 | Alternatively, you | |
1364 | can edit the working directory and update the index to fix your | |
1365 | mistake, just as if you were going to <<how-to-make-a-commit,create a | |
1366 | new commit>>, then run | |
1367 | ||
1368 | ------------------------------------------------- | |
1369 | $ git commit --amend | |
1370 | ------------------------------------------------- | |
1371 | ||
1372 | which will replace the old commit by a new commit incorporating your | |
1373 | changes, giving you a chance to edit the old commit message first. | |
1374 | ||
1375 | Again, you should never do this to a commit that may already have | |
1376 | been merged into another branch; use gitlink:git-revert[1] instead in | |
1377 | that case. | |
1378 | ||
1379 | It is also possible to edit commits further back in the history, but | |
1380 | this is an advanced topic to be left for | |
1381 | <<cleaning-up-history,another chapter>>. | |
1382 | ||
1383 | Checking out an old version of a file | |
1384 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
1385 | ||
1386 | In the process of undoing a previous bad change, you may find it | |
1387 | useful to check out an older version of a particular file using | |
1388 | gitlink:git-checkout[1]. We've used git checkout before to switch | |
1389 | branches, but it has quite different behavior if it is given a path | |
1390 | name: the command | |
1391 | ||
1392 | ------------------------------------------------- | |
1393 | $ git checkout HEAD^ path/to/file | |
1394 | ------------------------------------------------- | |
1395 | ||
1396 | replaces path/to/file by the contents it had in the commit HEAD^, and | |
1397 | also updates the index to match. It does not change branches. | |
1398 | ||
1399 | If you just want to look at an old version of the file, without | |
1400 | modifying the working directory, you can do that with | |
1401 | gitlink:git-show[1]: | |
1402 | ||
1403 | ------------------------------------------------- | |
1404 | $ git show HEAD^ path/to/file | |
1405 | ------------------------------------------------- | |
1406 | ||
1407 | which will display the given version of the file. | |
1408 | ||
1409 | Working with other version control systems | |
1410 | ========================================== | |
1411 | ||
1412 | TODO: CVS, Subversion, ? | |
1413 | ||
1414 | [[cleaning-up-history]] | |
1415 | Cleaning up history: rebasing, cherry-picking, and patch series | |
1416 | =============================================================== | |
1417 | ||
1418 | TODO: rebase, cherry-pick, pointers to other tools (like stgit) | |
1419 | ||
1420 | Git internals | |
1421 | ============= | |
1422 | ||
1423 | Architectural overview | |
1424 | ---------------------- | |
1425 | ||
1426 | TODO: Sources, README, core-tutorial, tutorial-2.txt, technical/ | |
1427 | ||
1428 | Glossary of git terms | |
1429 | ===================== | |
1430 | ||
1431 | include::glossary.txt[] | |
1432 | ||
1433 | Todo list for this manual | |
1434 | ========================= | |
1435 | ||
1436 | Scan Documentation/ for other stuff left out; in particular: | |
1437 | howto's | |
1438 | README | |
1439 | some of technical/? | |
1440 | hooks | |
1441 | etc. | |
1442 | ||
1443 | Scan email archives for other stuff left out | |
1444 | ||
1445 | Scan man pages to see if any assume more background than this manual | |
1446 | provides. | |
1447 | ||
1448 | Mention of gitweb. | |
1449 | ||
1450 | Update git fetch discussion to use "git remote" setup. That will | |
1451 | make things simpler. Maybe wait till git remote is done. | |
1452 | ||
1453 | Can also simplify beginning by suggesting disconnected head instead | |
1454 | of temporary branch creation. | |
1455 | ||
1456 | Explain how to refer to file stages in the "how to resolve a merge" | |
1457 | section: diff -1, -2, -3; :1:/path notation. | |
1458 | ||
1459 | Include cross-references to the glossary, where appropriate. | |
1460 |