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Junio C Hamano4cd1c0e2007-08-06 04:39:141Git User's Manual (for version 1.5.3 or newer)
Junio C Hamano67fad6d2007-05-06 08:53:122______________________________________________
Junio C Hamano8f62db92007-02-01 00:22:223
Junio C Hamano75485c82007-05-19 04:20:334
5Git is a fast distributed revision control system.
6
Junio C Hamanoa6387422007-08-25 03:54:277This manual is designed to be readable by someone with basic UNIX
Junio C Hamanodb911ee2007-02-28 08:13:528command-line skills, but no previous knowledge of git.
Junio C Hamano8f62db92007-02-01 00:22:229
Junio C Hamano75485c82007-05-19 04:20:3310<<repositories-and-branches>> and <<exploring-git-history>> explain how
11to fetch and study a project using git--read these chapters to learn how
12to build and test a particular version of a software project, search for
13regressions, and so on.
Junio C Hamano8f62db92007-02-01 00:22:2214
Junio C Hamano75485c82007-05-19 04:20:3315People needing to do actual development will also want to read
Junio C Hamanoec87f522008-12-10 08:35:2516<<Developing-With-git>> and <<sharing-development>>.
Junio C Hamano8f62db92007-02-01 00:22:2217
18Further chapters cover more specialized topics.
19
20Comprehensive reference documentation is available through the man
Junio C Hamanof66ecee2008-11-17 18:25:4321pages, or linkgit:git-help[1] command. For example, for the command
22"git clone <repo>", you can either use:
Junio C Hamano8f62db92007-02-01 00:22:2223
24------------------------------------------------
25$ man git-clone
26------------------------------------------------
27
Junio C Hamanof66ecee2008-11-17 18:25:4328or:
29
30------------------------------------------------
31$ git help clone
32------------------------------------------------
33
34With the latter, you can use the manual viewer of your choice; see
35linkgit:git-help[1] for more information.
36
Junio C Hamano75485c82007-05-19 04:20:3337See also <<git-quick-start>> for a brief overview of git commands,
38without any explanation.
Junio C Hamano8f62db92007-02-01 00:22:2239
Junio C Hamanof614c642007-06-11 01:21:5440Finally, see <<todo>> for ways that you can help make this manual more
Junio C Hamano75485c82007-05-19 04:20:3341complete.
Junio C Hamano8f62db92007-02-01 00:22:2242
Junio C Hamano8f62db92007-02-01 00:22:2243
Junio C Hamano3d30fd52007-05-08 00:32:5344[[repositories-and-branches]]
Junio C Hamano8f62db92007-02-01 00:22:2245Repositories and Branches
46=========================
47
Junio C Hamano3d30fd52007-05-08 00:32:5348[[how-to-get-a-git-repository]]
Junio C Hamano8f62db92007-02-01 00:22:2249How to get a git repository
50---------------------------
51
52It will be useful to have a git repository to experiment with as you
53read this manual.
54
Junio C Hamano35738e82008-01-07 07:55:4655The best way to get one is by using the linkgit:git-clone[1] command to
Junio C Hamano8b8b0f22007-08-26 22:10:2656download a copy of an existing repository. If you don't already have a
57project in mind, here are some interesting examples:
Junio C Hamano8f62db92007-02-01 00:22:2258
59------------------------------------------------
60# git itself (approx. 10MB download):
61$ git clone git://git.kernel.org/pub/scm/git/git.git
Junio C Hamano4fbdd442009-01-06 05:56:2462# the Linux kernel (approx. 150MB download):
Junio C Hamano8f62db92007-02-01 00:22:2263$ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
64------------------------------------------------
65
66The initial clone may be time-consuming for a large project, but you
67will only need to clone once.
68
Junio C Hamanoce3650e2007-11-26 04:20:1169The clone command creates a new directory named after the project ("git"
70or "linux-2.6" in the examples above). After you cd into this
Junio C Hamano8f62db92007-02-01 00:22:2271directory, you will see that it contains a copy of the project files,
Junio C Hamanoce3650e2007-11-26 04:20:1172called the <<def_working_tree,working tree>>, together with a special
73top-level directory named ".git", which contains all the information
74about the history of the project.
Junio C Hamano8f62db92007-02-01 00:22:2275
Junio C Hamano3d30fd52007-05-08 00:32:5376[[how-to-check-out]]
Junio C Hamano8f62db92007-02-01 00:22:2277How to check out a different version of a project
78-------------------------------------------------
79
Junio C Hamano8b8b0f22007-08-26 22:10:2680Git is best thought of as a tool for storing the history of a collection
81of files. It stores the history as a compressed collection of
82interrelated snapshots of the project's contents. In git each such
83version is called a <<def_commit,commit>>.
Junio C Hamano8f62db92007-02-01 00:22:2284
Junio C Hamanoce3650e2007-11-26 04:20:1185Those snapshots aren't necessarily all arranged in a single line from
86oldest to newest; instead, work may simultaneously proceed along
Junio C Hamano618bdde2008-01-02 10:51:0887parallel lines of development, called <<def_branch,branches>>, which may
Junio C Hamanoce3650e2007-11-26 04:20:1188merge and diverge.
89
90A single git repository can track development on multiple branches. It
91does this by keeping a list of <<def_head,heads>> which reference the
Junio C Hamano35738e82008-01-07 07:55:4692latest commit on each branch; the linkgit:git-branch[1] command shows
Junio C Hamano3d5b41f2007-03-26 02:33:4193you the list of branch heads:
Junio C Hamano8f62db92007-02-01 00:22:2294
95------------------------------------------------
96$ git branch
97* master
98------------------------------------------------
99
Junio C Hamano0e3cb532007-04-17 08:28:11100A freshly cloned repository contains a single branch head, by default
101named "master", with the working directory initialized to the state of
102the project referred to by that branch head.
Junio C Hamano8f62db92007-02-01 00:22:22103
Junio C Hamano3d5b41f2007-03-26 02:33:41104Most projects also use <<def_tag,tags>>. Tags, like heads, are
105references into the project's history, and can be listed using the
Junio C Hamano35738e82008-01-07 07:55:46106linkgit:git-tag[1] command:
Junio C Hamano8f62db92007-02-01 00:22:22107
108------------------------------------------------
109$ git tag -l
110v2.6.11
111v2.6.11-tree
112v2.6.12
113v2.6.12-rc2
114v2.6.12-rc3
115v2.6.12-rc4
116v2.6.12-rc5
117v2.6.12-rc6
118v2.6.13
119...
120------------------------------------------------
121
122Tags are expected to always point at the same version of a project,
Junio C Hamano3d5b41f2007-03-26 02:33:41123while heads are expected to advance as development progresses.
Junio C Hamano8f62db92007-02-01 00:22:22124
Junio C Hamano3d5b41f2007-03-26 02:33:41125Create a new branch head pointing to one of these versions and check it
Junio C Hamano35738e82008-01-07 07:55:46126out using linkgit:git-checkout[1]:
Junio C Hamano8f62db92007-02-01 00:22:22127
128------------------------------------------------
129$ git checkout -b new v2.6.13
130------------------------------------------------
131
132The working directory then reflects the contents that the project had
Junio C Hamano35738e82008-01-07 07:55:46133when it was tagged v2.6.13, and linkgit:git-branch[1] shows two
Junio C Hamano8f62db92007-02-01 00:22:22134branches, with an asterisk marking the currently checked-out branch:
135
136------------------------------------------------
137$ git branch
138 master
139* new
140------------------------------------------------
141
142If you decide that you'd rather see version 2.6.17, you can modify
143the current branch to point at v2.6.17 instead, with
144
145------------------------------------------------
146$ git reset --hard v2.6.17
147------------------------------------------------
148
Junio C Hamano3d5b41f2007-03-26 02:33:41149Note that if the current branch head was your only reference to a
Junio C Hamano8f62db92007-02-01 00:22:22150particular point in history, then resetting that branch may leave you
Junio C Hamano3d5b41f2007-03-26 02:33:41151with no way to find the history it used to point to; so use this command
152carefully.
Junio C Hamano8f62db92007-02-01 00:22:22153
Junio C Hamano3d30fd52007-05-08 00:32:53154[[understanding-commits]]
Junio C Hamano8f62db92007-02-01 00:22:22155Understanding History: Commits
156------------------------------
157
158Every change in the history of a project is represented by a commit.
Junio C Hamano35738e82008-01-07 07:55:46159The linkgit:git-show[1] command shows the most recent commit on the
Junio C Hamano8f62db92007-02-01 00:22:22160current branch:
161
162------------------------------------------------
163$ git show
Junio C Hamano8b8b0f22007-08-26 22:10:26164commit 17cf781661e6d38f737f15f53ab552f1e95960d7
165Author: Linus Torvalds <torvalds@ppc970.osdl.org.(none)>
166Date: Tue Apr 19 14:11:06 2005 -0700
Junio C Hamano8f62db92007-02-01 00:22:22167
Junio C Hamano8b8b0f22007-08-26 22:10:26168 Remove duplicate getenv(DB_ENVIRONMENT) call
Junio C Hamanoa77a5132007-06-08 16:13:44169
Junio C Hamano8b8b0f22007-08-26 22:10:26170 Noted by Tony Luck.
Junio C Hamanoa77a5132007-06-08 16:13:44171
Junio C Hamano8b8b0f22007-08-26 22:10:26172diff --git a/init-db.c b/init-db.c
173index 65898fa..b002dc6 100644
174--- a/init-db.c
175+++ b/init-db.c
176@@ -7,7 +7,7 @@
177
178 int main(int argc, char **argv)
179 {
180- char *sha1_dir = getenv(DB_ENVIRONMENT), *path;
181+ char *sha1_dir, *path;
182 int len, i;
183
184 if (mkdir(".git", 0755) < 0) {
Junio C Hamano8f62db92007-02-01 00:22:22185------------------------------------------------
186
187As you can see, a commit shows who made the latest change, what they
188did, and why.
189
Junio C Hamanoaa83a7d2007-03-05 02:37:29190Every commit has a 40-hexdigit id, sometimes called the "object name" or the
Junio C Hamano5f9a6f02009-04-06 08:26:56191"SHA-1 id", shown on the first line of the "git show" output. You can usually
Junio C Hamanoaa83a7d2007-03-05 02:37:29192refer to a commit by a shorter name, such as a tag or a branch name, but this
193longer name can also be useful. Most importantly, it is a globally unique
194name for this commit: so if you tell somebody else the object name (for
195example in email), then you are guaranteed that name will refer to the same
196commit in their repository that it does in yours (assuming their repository
197has that commit at all). Since the object name is computed as a hash over the
198contents of the commit, you are guaranteed that the commit can never change
199without its name also changing.
200
Junio C Hamano597ffcf2007-09-17 17:33:15201In fact, in <<git-concepts>> we shall see that everything stored in git
Junio C Hamanoaa83a7d2007-03-05 02:37:29202history, including file data and directory contents, is stored in an object
203with a name that is a hash of its contents.
Junio C Hamano8f62db92007-02-01 00:22:22204
Junio C Hamano3d30fd52007-05-08 00:32:53205[[understanding-reachability]]
Junio C Hamano8f62db92007-02-01 00:22:22206Understanding history: commits, parents, and reachability
207~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
208
209Every commit (except the very first commit in a project) also has a
210parent commit which shows what happened before this commit.
211Following the chain of parents will eventually take you back to the
212beginning of the project.
213
214However, the commits do not form a simple list; git allows lines of
215development to diverge and then reconverge, and the point where two
216lines of development reconverge is called a "merge". The commit
217representing a merge can therefore have more than one parent, with
218each parent representing the most recent commit on one of the lines
219of development leading to that point.
220
Junio C Hamano35738e82008-01-07 07:55:46221The best way to see how this works is using the linkgit:gitk[1]
Junio C Hamano8f62db92007-02-01 00:22:22222command; running gitk now on a git repository and looking for merge
223commits will help understand how the git organizes history.
224
225In the following, we say that commit X is "reachable" from commit Y
226if commit X is an ancestor of commit Y. Equivalently, you could say
Junio C Hamanoa6387422007-08-25 03:54:27227that Y is a descendant of X, or that there is a chain of parents
Junio C Hamano8f62db92007-02-01 00:22:22228leading from commit Y to commit X.
229
Junio C Hamano3d30fd52007-05-08 00:32:53230[[history-diagrams]]
Junio C Hamanoee1e4282007-02-04 08:32:04231Understanding history: History diagrams
232~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Junio C Hamano8f62db92007-02-01 00:22:22233
234We will sometimes represent git history using diagrams like the one
235below. Commits are shown as "o", and the links between them with
236lines drawn with - / and \. Time goes left to right:
237
Junio C Hamanoc51fede2007-03-12 07:29:20238
239................................................
Junio C Hamano8f62db92007-02-01 00:22:22240 o--o--o <-- Branch A
241 /
242 o--o--o <-- master
243 \
244 o--o--o <-- Branch B
Junio C Hamanoc51fede2007-03-12 07:29:20245................................................
Junio C Hamano8f62db92007-02-01 00:22:22246
247If we need to talk about a particular commit, the character "o" may
248be replaced with another letter or number.
249
Junio C Hamano3d30fd52007-05-08 00:32:53250[[what-is-a-branch]]
Junio C Hamano8f62db92007-02-01 00:22:22251Understanding history: What is a branch?
252~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
253
Junio C Hamano3d5b41f2007-03-26 02:33:41254When we need to be precise, we will use the word "branch" to mean a line
255of development, and "branch head" (or just "head") to mean a reference
256to the most recent commit on a branch. In the example above, the branch
257head named "A" is a pointer to one particular commit, but we refer to
258the line of three commits leading up to that point as all being part of
Junio C Hamano8f62db92007-02-01 00:22:22259"branch A".
260
Junio C Hamano3d5b41f2007-03-26 02:33:41261However, when no confusion will result, we often just use the term
262"branch" both for branches and for branch heads.
Junio C Hamano8f62db92007-02-01 00:22:22263
Junio C Hamano3d30fd52007-05-08 00:32:53264[[manipulating-branches]]
Junio C Hamano8f62db92007-02-01 00:22:22265Manipulating branches
266---------------------
267
268Creating, deleting, and modifying branches is quick and easy; here's
269a summary of the commands:
270
271git branch::
272list all branches
273git branch <branch>::
274create a new branch named <branch>, referencing the same
275point in history as the current branch
276git branch <branch> <start-point>::
277create a new branch named <branch>, referencing
278<start-point>, which may be specified any way you like,
279including using a branch name or a tag name
280git branch -d <branch>::
281delete the branch <branch>; if the branch you are deleting
Junio C Hamano3d30fd52007-05-08 00:32:53282points to a commit which is not reachable from the current
283branch, this command will fail with a warning.
Junio C Hamano8f62db92007-02-01 00:22:22284git branch -D <branch>::
285even if the branch points to a commit not reachable
286from the current branch, you may know that that commit
287is still reachable from some other branch or tag. In that
288case it is safe to use this command to force git to delete
289the branch.
290git checkout <branch>::
291make the current branch <branch>, updating the working
292directory to reflect the version referenced by <branch>
293git checkout -b <new> <start-point>::
294create a new branch <new> referencing <start-point>, and
295check it out.
296
Junio C Hamano0e3cb532007-04-17 08:28:11297The special symbol "HEAD" can always be used to refer to the current
298branch. In fact, git uses a file named "HEAD" in the .git directory to
299remember which branch is current:
300
301------------------------------------------------
302$ cat .git/HEAD
303ref: refs/heads/master
304------------------------------------------------
305
306[[detached-head]]
307Examining an old version without creating a new branch
308------------------------------------------------------
309
Junio C Hamano5f9a6f02009-04-06 08:26:56310The `git checkout` command normally expects a branch head, but will also
Junio C Hamano0e3cb532007-04-17 08:28:11311accept an arbitrary commit; for example, you can check out the commit
312referenced by a tag:
313
314------------------------------------------------
315$ git checkout v2.6.17
316Note: moving to "v2.6.17" which isn't a local branch
317If you want to create a new branch from this checkout, you may do so
318(now or later) by using -b with the checkout command again. Example:
319 git checkout -b <new_branch_name>
320HEAD is now at 427abfa... Linux v2.6.17
321------------------------------------------------
322
Junio C Hamano5f9a6f02009-04-06 08:26:56323The HEAD then refers to the SHA-1 of the commit instead of to a branch,
Junio C Hamano0e3cb532007-04-17 08:28:11324and git branch shows that you are no longer on a branch:
325
326------------------------------------------------
327$ cat .git/HEAD
328427abfa28afedffadfca9dd8b067eb6d36bac53f
Junio C Hamano3d30fd52007-05-08 00:32:53329$ git branch
Junio C Hamano0e3cb532007-04-17 08:28:11330* (no branch)
331 master
332------------------------------------------------
333
334In this case we say that the HEAD is "detached".
335
Junio C Hamano3d30fd52007-05-08 00:32:53336This is an easy way to check out a particular version without having to
337make up a name for the new branch. You can still create a new branch
338(or tag) for this version later if you decide to.
Junio C Hamano8f62db92007-02-01 00:22:22339
Junio C Hamano3d30fd52007-05-08 00:32:53340[[examining-remote-branches]]
Junio C Hamano8f62db92007-02-01 00:22:22341Examining branches from a remote repository
342-------------------------------------------
343
344The "master" branch that was created at the time you cloned is a copy
345of the HEAD in the repository that you cloned from. That repository
346may also have had other branches, though, and your local repository
347keeps branches which track each of those remote branches, which you
Junio C Hamano35738e82008-01-07 07:55:46348can view using the "-r" option to linkgit:git-branch[1]:
Junio C Hamano8f62db92007-02-01 00:22:22349
350------------------------------------------------
351$ git branch -r
352 origin/HEAD
353 origin/html
354 origin/maint
355 origin/man
356 origin/master
357 origin/next
358 origin/pu
359 origin/todo
360------------------------------------------------
361
362You cannot check out these remote-tracking branches, but you can
363examine them on a branch of your own, just as you would a tag:
364
365------------------------------------------------
366$ git checkout -b my-todo-copy origin/todo
367------------------------------------------------
368
369Note that the name "origin" is just the name that git uses by default
370to refer to the repository that you cloned from.
371
372[[how-git-stores-references]]
373Naming branches, tags, and other references
374-------------------------------------------
375
376Branches, remote-tracking branches, and tags are all references to
377commits. All references are named with a slash-separated path name
378starting with "refs"; the names we've been using so far are actually
379shorthand:
380
381- The branch "test" is short for "refs/heads/test".
382- The tag "v2.6.18" is short for "refs/tags/v2.6.18".
383- "origin/master" is short for "refs/remotes/origin/master".
384
385The full name is occasionally useful if, for example, there ever
386exists a tag and a branch with the same name.
387
Junio C Hamano9810d632007-09-24 01:05:34388(Newly created refs are actually stored in the .git/refs directory,
389under the path given by their name. However, for efficiency reasons
390they may also be packed together in a single file; see
Junio C Hamano35738e82008-01-07 07:55:46391linkgit:git-pack-refs[1]).
Junio C Hamano9810d632007-09-24 01:05:34392
Junio C Hamano3d30fd52007-05-08 00:32:53393As another useful shortcut, the "HEAD" of a repository can be referred
394to just using the name of that repository. So, for example, "origin"
395is usually a shortcut for the HEAD branch in the repository "origin".
Junio C Hamano8f62db92007-02-01 00:22:22396
397For the complete list of paths which git checks for references, and
398the order it uses to decide which to choose when there are multiple
399references with the same shorthand name, see the "SPECIFYING
Junio C Hamanoc27b7332010-10-14 04:37:28400REVISIONS" section of linkgit:gitrevisions[7].
Junio C Hamano8f62db92007-02-01 00:22:22401
Junio C Hamanoec87f522008-12-10 08:35:25402[[Updating-a-repository-With-git-fetch]]
Junio C Hamano5f9a6f02009-04-06 08:26:56403Updating a repository with git fetch
Junio C Hamano8f62db92007-02-01 00:22:22404------------------------------------
405
406Eventually the developer cloned from will do additional work in her
407repository, creating new commits and advancing the branches to point
408at the new commits.
409
410The command "git fetch", with no arguments, will update all of the
411remote-tracking branches to the latest version found in her
412repository. It will not touch any of your own branches--not even the
413"master" branch that was created for you on clone.
414
Junio C Hamano3d30fd52007-05-08 00:32:53415[[fetching-branches]]
Junio C Hamano8f62db92007-02-01 00:22:22416Fetching branches from other repositories
417-----------------------------------------
418
419You can also track branches from repositories other than the one you
Junio C Hamano35738e82008-01-07 07:55:46420cloned from, using linkgit:git-remote[1]:
Junio C Hamano8f62db92007-02-01 00:22:22421
422-------------------------------------------------
423$ git remote add linux-nfs git://linux-nfs.org/pub/nfs-2.6.git
Junio C Hamano4c6aa8a2007-04-04 08:56:37424$ git fetch linux-nfs
Junio C Hamano8f62db92007-02-01 00:22:22425* refs/remotes/linux-nfs/master: storing branch 'master' ...
426 commit: bf81b46
427-------------------------------------------------
428
429New remote-tracking branches will be stored under the shorthand name
Junio C Hamano5f9a6f02009-04-06 08:26:56430that you gave "git remote add", in this case linux-nfs:
Junio C Hamano8f62db92007-02-01 00:22:22431
432-------------------------------------------------
433$ git branch -r
434linux-nfs/master
435origin/master
436-------------------------------------------------
437
438If you run "git fetch <remote>" later, the tracking branches for the
439named <remote> will be updated.
440
441If you examine the file .git/config, you will see that git has added
442a new stanza:
443
444-------------------------------------------------
445$ cat .git/config
446...
447[remote "linux-nfs"]
Junio C Hamanoc51fede2007-03-12 07:29:20448url = git://linux-nfs.org/pub/nfs-2.6.git
449fetch = +refs/heads/*:refs/remotes/linux-nfs/*
Junio C Hamano8f62db92007-02-01 00:22:22450...
451-------------------------------------------------
452
453This is what causes git to track the remote's branches; you may modify
454or delete these configuration options by editing .git/config with a
455text editor. (See the "CONFIGURATION FILE" section of
Junio C Hamano35738e82008-01-07 07:55:46456linkgit:git-config[1] for details.)
Junio C Hamano8f62db92007-02-01 00:22:22457
Junio C Hamano3d30fd52007-05-08 00:32:53458[[exploring-git-history]]
Junio C Hamano8f62db92007-02-01 00:22:22459Exploring git history
460=====================
461
462Git is best thought of as a tool for storing the history of a
463collection of files. It does this by storing compressed snapshots of
Junio C Hamanocc13f552007-07-24 08:59:43464the contents of a file hierarchy, together with "commits" which show
Junio C Hamano8f62db92007-02-01 00:22:22465the relationships between these snapshots.
466
467Git provides extremely flexible and fast tools for exploring the
468history of a project.
469
Junio C Hamano39381a72007-02-02 07:35:15470We start with one specialized tool that is useful for finding the
Junio C Hamano8f62db92007-02-01 00:22:22471commit that introduced a bug into a project.
472
Junio C Hamano3d30fd52007-05-08 00:32:53473[[using-bisect]]
Junio C Hamano8f62db92007-02-01 00:22:22474How to use bisect to find a regression
475--------------------------------------
476
477Suppose version 2.6.18 of your project worked, but the version at
478"master" crashes. Sometimes the best way to find the cause of such a
479regression is to perform a brute-force search through the project's
480history to find the particular commit that caused the problem. The
Junio C Hamano35738e82008-01-07 07:55:46481linkgit:git-bisect[1] command can help you do this:
Junio C Hamano8f62db92007-02-01 00:22:22482
483-------------------------------------------------
484$ git bisect start
485$ git bisect good v2.6.18
486$ git bisect bad master
487Bisecting: 3537 revisions left to test after this
488[65934a9a028b88e83e2b0f8b36618fe503349f8e] BLOCK: Make USB storage depend on SCSI rather than selecting it [try #6]
489-------------------------------------------------
490
491If you run "git branch" at this point, you'll see that git has
Junio C Hamano9e395072008-07-31 22:11:21492temporarily moved you in "(no branch)". HEAD is now detached from any
493branch and points directly to a commit (with commit id 65934...) that
494is reachable from "master" but not from v2.6.18. Compile and test it,
495and see whether it crashes. Assume it does crash. Then:
Junio C Hamano8f62db92007-02-01 00:22:22496
497-------------------------------------------------
498$ git bisect bad
499Bisecting: 1769 revisions left to test after this
500[7eff82c8b1511017ae605f0c99ac275a7e21b867] i2c-core: Drop useless bitmaskings
501-------------------------------------------------
502
503checks out an older version. Continue like this, telling git at each
504stage whether the version it gives you is good or bad, and notice
505that the number of revisions left to test is cut approximately in
506half each time.
507
508After about 13 tests (in this case), it will output the commit id of
509the guilty commit. You can then examine the commit with
Junio C Hamano35738e82008-01-07 07:55:46510linkgit:git-show[1], find out who wrote it, and mail them your bug
Junio C Hamano8f62db92007-02-01 00:22:22511report with the commit id. Finally, run
512
513-------------------------------------------------
514$ git bisect reset
515-------------------------------------------------
516
Junio C Hamano9e395072008-07-31 22:11:21517to return you to the branch you were on before.
Junio C Hamano8f62db92007-02-01 00:22:22518
Junio C Hamano5f9a6f02009-04-06 08:26:56519Note that the version which `git bisect` checks out for you at each
Junio C Hamano8f62db92007-02-01 00:22:22520point is just a suggestion, and you're free to try a different
521version if you think it would be a good idea. For example,
522occasionally you may land on a commit that broke something unrelated;
523run
524
525-------------------------------------------------
Junio C Hamano4c6aa8a2007-04-04 08:56:37526$ git bisect visualize
Junio C Hamano8f62db92007-02-01 00:22:22527-------------------------------------------------
528
529which will run gitk and label the commit it chose with a marker that
Junio C Hamanod32738e2008-07-09 19:53:42530says "bisect". Choose a safe-looking commit nearby, note its commit
Junio C Hamano8f62db92007-02-01 00:22:22531id, and check it out with:
532
533-------------------------------------------------
534$ git reset --hard fb47ddb2db...
535-------------------------------------------------
536
537then test, run "bisect good" or "bisect bad" as appropriate, and
538continue.
539
Junio C Hamano9e395072008-07-31 22:11:21540Instead of "git bisect visualize" and then "git reset --hard
541fb47ddb2db...", you might just want to tell git that you want to skip
542the current commit:
543
544-------------------------------------------------
545$ git bisect skip
546-------------------------------------------------
547
548In this case, though, git may not eventually be able to tell the first
Junio C Hamano610d1762008-11-28 06:27:13549bad one between some first skipped commits and a later bad commit.
Junio C Hamano9e395072008-07-31 22:11:21550
551There are also ways to automate the bisecting process if you have a
552test script that can tell a good from a bad commit. See
553linkgit:git-bisect[1] for more information about this and other "git
554bisect" features.
555
Junio C Hamano3d30fd52007-05-08 00:32:53556[[naming-commits]]
Junio C Hamano8f62db92007-02-01 00:22:22557Naming commits
558--------------
559
560We have seen several ways of naming commits already:
561
562- 40-hexdigit object name
563- branch name: refers to the commit at the head of the given
564 branch
565- tag name: refers to the commit pointed to by the given tag
566 (we've seen branches and tags are special cases of
567 <<how-git-stores-references,references>>).
568- HEAD: refers to the head of the current branch
569
570There are many more; see the "SPECIFYING REVISIONS" section of the
Junio C Hamanoc27b7332010-10-14 04:37:28571linkgit:gitrevisions[7] man page for the complete list of ways to
Junio C Hamano8f62db92007-02-01 00:22:22572name revisions. Some examples:
573
574-------------------------------------------------
575$ git show fb47ddb2 # the first few characters of the object name
576 # are usually enough to specify it uniquely
577$ git show HEAD^ # the parent of the HEAD commit
578$ git show HEAD^^ # the grandparent
579$ git show HEAD~4 # the great-great-grandparent
580-------------------------------------------------
581
582Recall that merge commits may have more than one parent; by default,
583^ and ~ follow the first parent listed in the commit, but you can
584also choose:
585
586-------------------------------------------------
587$ git show HEAD^1 # show the first parent of HEAD
588$ git show HEAD^2 # show the second parent of HEAD
589-------------------------------------------------
590
591In addition to HEAD, there are several other special names for
592commits:
593
594Merges (to be discussed later), as well as operations such as
Junio C Hamano5f9a6f02009-04-06 08:26:56595`git reset`, which change the currently checked-out commit, generally
Junio C Hamano8f62db92007-02-01 00:22:22596set ORIG_HEAD to the value HEAD had before the current operation.
597
Junio C Hamano5f9a6f02009-04-06 08:26:56598The `git fetch` operation always stores the head of the last fetched
599branch in FETCH_HEAD. For example, if you run `git fetch` without
Junio C Hamano8f62db92007-02-01 00:22:22600specifying a local branch as the target of the operation
601
602-------------------------------------------------
603$ git fetch git://example.com/proj.git theirbranch
604-------------------------------------------------
605
606the fetched commits will still be available from FETCH_HEAD.
607
608When we discuss merges we'll also see the special name MERGE_HEAD,
609which refers to the other branch that we're merging in to the current
610branch.
611
Junio C Hamano35738e82008-01-07 07:55:46612The linkgit:git-rev-parse[1] command is a low-level command that is
Junio C Hamano8f62db92007-02-01 00:22:22613occasionally useful for translating some name for a commit to the object
614name for that commit:
615
616-------------------------------------------------
617$ git rev-parse origin
618e05db0fd4f31dde7005f075a84f96b360d05984b
619-------------------------------------------------
620
Junio C Hamano3d30fd52007-05-08 00:32:53621[[creating-tags]]
Junio C Hamano8f62db92007-02-01 00:22:22622Creating tags
623-------------
624
625We can also create a tag to refer to a particular commit; after
626running
627
628-------------------------------------------------
Junio C Hamano4c6aa8a2007-04-04 08:56:37629$ git tag stable-1 1b2e1d63ff
Junio C Hamano8f62db92007-02-01 00:22:22630-------------------------------------------------
631
632You can use stable-1 to refer to the commit 1b2e1d63ff.
633
Junio C Hamano3d30fd52007-05-08 00:32:53634This creates a "lightweight" tag. If you would also like to include a
635comment with the tag, and possibly sign it cryptographically, then you
Junio C Hamano35738e82008-01-07 07:55:46636should create a tag object instead; see the linkgit:git-tag[1] man page
Junio C Hamano3d30fd52007-05-08 00:32:53637for details.
Junio C Hamano8f62db92007-02-01 00:22:22638
Junio C Hamano3d30fd52007-05-08 00:32:53639[[browsing-revisions]]
Junio C Hamano8f62db92007-02-01 00:22:22640Browsing revisions
641------------------
642
Junio C Hamano35738e82008-01-07 07:55:46643The linkgit:git-log[1] command can show lists of commits. On its
Junio C Hamano8f62db92007-02-01 00:22:22644own, it shows all commits reachable from the parent commit; but you
645can also make more specific requests:
646
647-------------------------------------------------
648$ git log v2.5.. # commits since (not reachable from) v2.5
649$ git log test..master # commits reachable from master but not test
650$ git log master..test # ...reachable from test but not master
651$ git log master...test # ...reachable from either test or master,
652# but not both
653$ git log --since="2 weeks ago" # commits from the last 2 weeks
654$ git log Makefile # commits which modify Makefile
655$ git log fs/ # ... which modify any file under fs/
656$ git log -S'foo()' # commits which add or remove any file data
657# matching the string 'foo()'
658-------------------------------------------------
659
660And of course you can combine all of these; the following finds
661commits since v2.5 which touch the Makefile or any file under fs:
662
663-------------------------------------------------
664$ git log v2.5.. Makefile fs/
665-------------------------------------------------
666
667You can also ask git log to show patches:
668
669-------------------------------------------------
670$ git log -p
671-------------------------------------------------
672
Junio C Hamano35738e82008-01-07 07:55:46673See the "--pretty" option in the linkgit:git-log[1] man page for more
Junio C Hamano8f62db92007-02-01 00:22:22674display options.
675
676Note that git log starts with the most recent commit and works
677backwards through the parents; however, since git history can contain
Junio C Hamanoee1e4282007-02-04 08:32:04678multiple independent lines of development, the particular order that
Junio C Hamano8f62db92007-02-01 00:22:22679commits are listed in may be somewhat arbitrary.
680
Junio C Hamano3d30fd52007-05-08 00:32:53681[[generating-diffs]]
Junio C Hamano8f62db92007-02-01 00:22:22682Generating diffs
683----------------
684
685You can generate diffs between any two versions using
Junio C Hamano35738e82008-01-07 07:55:46686linkgit:git-diff[1]:
Junio C Hamano8f62db92007-02-01 00:22:22687
688-------------------------------------------------
689$ git diff master..test
690-------------------------------------------------
691
Junio C Hamano393e57f2007-11-20 04:53:25692That will produce the diff between the tips of the two branches. If
693you'd prefer to find the diff from their common ancestor to test, you
694can use three dots instead of two:
695
696-------------------------------------------------
697$ git diff master...test
698-------------------------------------------------
699
700Sometimes what you want instead is a set of patches; for this you can
Junio C Hamano35738e82008-01-07 07:55:46701use linkgit:git-format-patch[1]:
Junio C Hamano8f62db92007-02-01 00:22:22702
703-------------------------------------------------
704$ git format-patch master..test
705-------------------------------------------------
706
707will generate a file with a patch for each commit reachable from test
Junio C Hamano393e57f2007-11-20 04:53:25708but not from master.
Junio C Hamano8f62db92007-02-01 00:22:22709
Junio C Hamano3d30fd52007-05-08 00:32:53710[[viewing-old-file-versions]]
Junio C Hamano8f62db92007-02-01 00:22:22711Viewing old file versions
712-------------------------
713
714You can always view an old version of a file by just checking out the
715correct revision first. But sometimes it is more convenient to be
716able to view an old version of a single file without checking
717anything out; this command does that:
718
719-------------------------------------------------
720$ git show v2.5:fs/locks.c
721-------------------------------------------------
722
723Before the colon may be anything that names a commit, and after it
724may be any path to a file tracked by git.
725
Junio C Hamano3d30fd52007-05-08 00:32:53726[[history-examples]]
Junio C Hamano8f62db92007-02-01 00:22:22727Examples
728--------
729
Junio C Hamano75485c82007-05-19 04:20:33730[[counting-commits-on-a-branch]]
731Counting the number of commits on a branch
732~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
733
734Suppose you want to know how many commits you've made on "mybranch"
735since it diverged from "origin":
736
737-------------------------------------------------
738$ git log --pretty=oneline origin..mybranch | wc -l
739-------------------------------------------------
740
741Alternatively, you may often see this sort of thing done with the
Junio C Hamano5f9a6f02009-04-06 08:26:56742lower-level command linkgit:git-rev-list[1], which just lists the SHA-1's
Junio C Hamano75485c82007-05-19 04:20:33743of all the given commits:
744
745-------------------------------------------------
746$ git rev-list origin..mybranch | wc -l
747-------------------------------------------------
748
Junio C Hamano3d30fd52007-05-08 00:32:53749[[checking-for-equal-branches]]
Junio C Hamano8f62db92007-02-01 00:22:22750Check whether two branches point at the same history
751~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
752
753Suppose you want to check whether two branches point at the same point
754in history.
755
756-------------------------------------------------
757$ git diff origin..master
758-------------------------------------------------
759
760will tell you whether the contents of the project are the same at the
761two branches; in theory, however, it's possible that the same project
762contents could have been arrived at by two different historical
763routes. You could compare the object names:
764
765-------------------------------------------------
766$ git rev-list origin
767e05db0fd4f31dde7005f075a84f96b360d05984b
768$ git rev-list master
769e05db0fd4f31dde7005f075a84f96b360d05984b
770-------------------------------------------------
771
772Or you could recall that the ... operator selects all commits
773contained reachable from either one reference or the other but not
774both: so
775
776-------------------------------------------------
777$ git log origin...master
778-------------------------------------------------
779
780will return no commits when the two branches are equal.
781
Junio C Hamano3d30fd52007-05-08 00:32:53782[[finding-tagged-descendants]]
Junio C Hamano8f62db92007-02-01 00:22:22783Find first tagged version including a given fix
784~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
785
786Suppose you know that the commit e05db0fd fixed a certain problem.
787You'd like to find the earliest tagged release that contains that
788fix.
789
790Of course, there may be more than one answer--if the history branched
791after commit e05db0fd, then there could be multiple "earliest" tagged
792releases.
793
794You could just visually inspect the commits since e05db0fd:
795
796-------------------------------------------------
797$ gitk e05db0fd..
798-------------------------------------------------
799
Junio C Hamano35738e82008-01-07 07:55:46800Or you can use linkgit:git-name-rev[1], which will give the commit a
Junio C Hamano8f62db92007-02-01 00:22:22801name based on any tag it finds pointing to one of the commit's
802descendants:
803
804-------------------------------------------------
Junio C Hamano4c6aa8a2007-04-04 08:56:37805$ git name-rev --tags e05db0fd
Junio C Hamano8f62db92007-02-01 00:22:22806e05db0fd tags/v1.5.0-rc1^0~23
807-------------------------------------------------
808
Junio C Hamano35738e82008-01-07 07:55:46809The linkgit:git-describe[1] command does the opposite, naming the
Junio C Hamano8f62db92007-02-01 00:22:22810revision using a tag on which the given commit is based:
811
812-------------------------------------------------
813$ git describe e05db0fd
Junio C Hamano4c6aa8a2007-04-04 08:56:37814v1.5.0-rc0-260-ge05db0f
Junio C Hamano8f62db92007-02-01 00:22:22815-------------------------------------------------
816
817but that may sometimes help you guess which tags might come after the
818given commit.
819
820If you just want to verify whether a given tagged version contains a
Junio C Hamano35738e82008-01-07 07:55:46821given commit, you could use linkgit:git-merge-base[1]:
Junio C Hamano8f62db92007-02-01 00:22:22822
823-------------------------------------------------
824$ git merge-base e05db0fd v1.5.0-rc1
825e05db0fd4f31dde7005f075a84f96b360d05984b
826-------------------------------------------------
827
828The merge-base command finds a common ancestor of the given commits,
829and always returns one or the other in the case where one is a
830descendant of the other; so the above output shows that e05db0fd
831actually is an ancestor of v1.5.0-rc1.
832
833Alternatively, note that
834
835-------------------------------------------------
836$ git log v1.5.0-rc1..e05db0fd
837-------------------------------------------------
838
839will produce empty output if and only if v1.5.0-rc1 includes e05db0fd,
840because it outputs only commits that are not reachable from v1.5.0-rc1.
841
Junio C Hamano35738e82008-01-07 07:55:46842As yet another alternative, the linkgit:git-show-branch[1] command lists
Junio C Hamano8f62db92007-02-01 00:22:22843the commits reachable from its arguments with a display on the left-hand
844side that indicates which arguments that commit is reachable from. So,
845you can run something like
846
847-------------------------------------------------
848$ git show-branch e05db0fd v1.5.0-rc0 v1.5.0-rc1 v1.5.0-rc2
849! [e05db0fd] Fix warnings in sha1_file.c - use C99 printf format if
850available
851 ! [v1.5.0-rc0] GIT v1.5.0 preview
852 ! [v1.5.0-rc1] GIT v1.5.0-rc1
853 ! [v1.5.0-rc2] GIT v1.5.0-rc2
854...
855-------------------------------------------------
856
857then search for a line that looks like
858
859-------------------------------------------------
860+ ++ [e05db0fd] Fix warnings in sha1_file.c - use C99 printf format if
861available
862-------------------------------------------------
863
864Which shows that e05db0fd is reachable from itself, from v1.5.0-rc1, and
865from v1.5.0-rc2, but not from v1.5.0-rc0.
866
Junio C Hamano75485c82007-05-19 04:20:33867[[showing-commits-unique-to-a-branch]]
868Showing commits unique to a given branch
869~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
870
871Suppose you would like to see all the commits reachable from the branch
872head named "master" but not from any other head in your repository.
873
874We can list all the heads in this repository with
Junio C Hamano35738e82008-01-07 07:55:46875linkgit:git-show-ref[1]:
Junio C Hamano75485c82007-05-19 04:20:33876
877-------------------------------------------------
878$ git show-ref --heads
879bf62196b5e363d73353a9dcf094c59595f3153b7 refs/heads/core-tutorial
880db768d5504c1bb46f63ee9d6e1772bd047e05bf9 refs/heads/maint
881a07157ac624b2524a059a3414e99f6f44bebc1e7 refs/heads/master
88224dbc180ea14dc1aebe09f14c8ecf32010690627 refs/heads/tutorial-2
8831e87486ae06626c2f31eaa63d26fc0fd646c8af2 refs/heads/tutorial-fixes
884-------------------------------------------------
885
886We can get just the branch-head names, and remove "master", with
887the help of the standard utilities cut and grep:
888
889-------------------------------------------------
890$ git show-ref --heads | cut -d' ' -f2 | grep -v '^refs/heads/master'
891refs/heads/core-tutorial
892refs/heads/maint
893refs/heads/tutorial-2
894refs/heads/tutorial-fixes
895-------------------------------------------------
896
897And then we can ask to see all the commits reachable from master
898but not from these other heads:
899
900-------------------------------------------------
901$ gitk master --not $( git show-ref --heads | cut -d' ' -f2 |
902grep -v '^refs/heads/master' )
903-------------------------------------------------
904
905Obviously, endless variations are possible; for example, to see all
906commits reachable from some head but not from any tag in the repository:
907
908-------------------------------------------------
Junio C Hamano591dc6a2007-05-29 09:18:19909$ gitk $( git show-ref --heads ) --not $( git show-ref --tags )
Junio C Hamano75485c82007-05-19 04:20:33910-------------------------------------------------
911
Junio C Hamanoc27b7332010-10-14 04:37:28912(See linkgit:gitrevisions[7] for explanations of commit-selecting
Junio C Hamano75485c82007-05-19 04:20:33913syntax such as `--not`.)
914
915[[making-a-release]]
916Creating a changelog and tarball for a software release
917~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
918
Junio C Hamano35738e82008-01-07 07:55:46919The linkgit:git-archive[1] command can create a tar or zip archive from
Junio C Hamano75485c82007-05-19 04:20:33920any version of a project; for example:
921
922-------------------------------------------------
923$ git archive --format=tar --prefix=project/ HEAD | gzip >latest.tar.gz
924-------------------------------------------------
925
926will use HEAD to produce a tar archive in which each filename is
Junio C Hamano2a8f6dc2007-07-09 08:48:38927preceded by "project/".
Junio C Hamano75485c82007-05-19 04:20:33928
929If you're releasing a new version of a software project, you may want
930to simultaneously make a changelog to include in the release
931announcement.
932
933Linus Torvalds, for example, makes new kernel releases by tagging them,
934then running:
935
936-------------------------------------------------
937$ release-script 2.6.12 2.6.13-rc6 2.6.13-rc7
938-------------------------------------------------
939
940where release-script is a shell script that looks like:
941
942-------------------------------------------------
943#!/bin/sh
944stable="$1"
945last="$2"
946new="$3"
947echo "# git tag v$new"
948echo "git archive --prefix=linux-$new/ v$new | gzip -9 > ../linux-$new.tar.gz"
949echo "git diff v$stable v$new | gzip -9 > ../patch-$new.gz"
950echo "git log --no-merges v$new ^v$last > ../ChangeLog-$new"
951echo "git shortlog --no-merges v$new ^v$last > ../ShortLog"
952echo "git diff --stat --summary -M v$last v$new > ../diffstat-$new"
953-------------------------------------------------
954
955and then he just cut-and-pastes the output commands after verifying that
956they look OK.
Junio C Hamano8f62db92007-02-01 00:22:22957
Junio C Hamano3b4609d2010-09-30 00:04:34958[[Finding-commits-With-given-Content]]
Junio C Hamanoed7f4f62007-05-20 09:09:09959Finding commits referencing a file with given content
Junio C Hamano8b8b0f22007-08-26 22:10:26960~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Junio C Hamanoed7f4f62007-05-20 09:09:09961
962Somebody hands you a copy of a file, and asks which commits modified a
963file such that it contained the given content either before or after the
964commit. You can find out with this:
965
966-------------------------------------------------
Junio C Hamano764a6672007-10-23 01:23:31967$ git log --raw --abbrev=40 --pretty=oneline |
Junio C Hamanoed7f4f62007-05-20 09:09:09968grep -B 1 `git hash-object filename`
969-------------------------------------------------
970
971Figuring out why this works is left as an exercise to the (advanced)
Junio C Hamano35738e82008-01-07 07:55:46972student. The linkgit:git-log[1], linkgit:git-diff-tree[1], and
973linkgit:git-hash-object[1] man pages may prove helpful.
Junio C Hamanoed7f4f62007-05-20 09:09:09974
Junio C Hamanoec87f522008-12-10 08:35:25975[[Developing-With-git]]
Junio C Hamano8f62db92007-02-01 00:22:22976Developing with git
977===================
978
Junio C Hamano3d30fd52007-05-08 00:32:53979[[telling-git-your-name]]
Junio C Hamano8f62db92007-02-01 00:22:22980Telling git your name
981---------------------
982
983Before creating any commits, you should introduce yourself to git. The
Junio C Hamano3d30fd52007-05-08 00:32:53984easiest way to do so is to make sure the following lines appear in a
985file named .gitconfig in your home directory:
Junio C Hamano8f62db92007-02-01 00:22:22986
987------------------------------------------------
Junio C Hamano8f62db92007-02-01 00:22:22988[user]
989name = Your Name Comes Here
990email = you@yourdomain.example.com
Junio C Hamano8f62db92007-02-01 00:22:22991------------------------------------------------
992
Junio C Hamano35738e82008-01-07 07:55:46993(See the "CONFIGURATION FILE" section of linkgit:git-config[1] for
Junio C Hamano8f62db92007-02-01 00:22:22994details on the configuration file.)
995
996
Junio C Hamano3d30fd52007-05-08 00:32:53997[[creating-a-new-repository]]
Junio C Hamano8f62db92007-02-01 00:22:22998Creating a new repository
999-------------------------
1000
1001Creating a new repository from scratch is very easy:
1002
1003-------------------------------------------------
1004$ mkdir project
1005$ cd project
1006$ git init
1007-------------------------------------------------
1008
1009If you have some initial content (say, a tarball):
1010
1011-------------------------------------------------
Junio C Hamano4fbdd442009-01-06 05:56:241012$ tar xzvf project.tar.gz
Junio C Hamano8f62db92007-02-01 00:22:221013$ cd project
1014$ git init
1015$ git add . # include everything below ./ in the first commit:
1016$ git commit
1017-------------------------------------------------
1018
1019[[how-to-make-a-commit]]
Junio C Hamano12a3a232007-04-07 10:18:101020How to make a commit
Junio C Hamano8f62db92007-02-01 00:22:221021--------------------
1022
1023Creating a new commit takes three steps:
1024
10251. Making some changes to the working directory using your
1026 favorite editor.
10272. Telling git about your changes.
10283. Creating the commit using the content you told git about
1029 in step 2.
1030
1031In practice, you can interleave and repeat steps 1 and 2 as many
1032times as you want: in order to keep track of what you want committed
1033at step 3, git maintains a snapshot of the tree's contents in a
1034special staging area called "the index."
1035
1036At the beginning, the content of the index will be identical to
1037that of the HEAD. The command "git diff --cached", which shows
1038the difference between the HEAD and the index, should therefore
1039produce no output at that point.
1040
1041Modifying the index is easy:
1042
1043To update the index with the new contents of a modified file, use
1044
1045-------------------------------------------------
1046$ git add path/to/file
1047-------------------------------------------------
1048
1049To add the contents of a new file to the index, use
1050
1051-------------------------------------------------
1052$ git add path/to/file
1053-------------------------------------------------
1054
1055To remove a file from the index and from the working tree,
1056
1057-------------------------------------------------
1058$ git rm path/to/file
1059-------------------------------------------------
1060
1061After each step you can verify that
1062
1063-------------------------------------------------
1064$ git diff --cached
1065-------------------------------------------------
1066
1067always shows the difference between the HEAD and the index file--this
1068is what you'd commit if you created the commit now--and that
1069
1070-------------------------------------------------
1071$ git diff
1072-------------------------------------------------
1073
1074shows the difference between the working tree and the index file.
1075
Junio C Hamano5f9a6f02009-04-06 08:26:561076Note that "git add" always adds just the current contents of a file
Junio C Hamano8f62db92007-02-01 00:22:221077to the index; further changes to the same file will be ignored unless
Junio C Hamano5f9a6f02009-04-06 08:26:561078you run `git add` on the file again.
Junio C Hamano8f62db92007-02-01 00:22:221079
1080When you're ready, just run
1081
1082-------------------------------------------------
1083$ git commit
1084-------------------------------------------------
1085
1086and git will prompt you for a commit message and then create the new
Junio C Hamanoee1e4282007-02-04 08:32:041087commit. Check to make sure it looks like what you expected with
Junio C Hamano8f62db92007-02-01 00:22:221088
1089-------------------------------------------------
1090$ git show
1091-------------------------------------------------
1092
1093As a special shortcut,
Junio C Hamanoa77a5132007-06-08 16:13:441094
Junio C Hamano8f62db92007-02-01 00:22:221095-------------------------------------------------
1096$ git commit -a
1097-------------------------------------------------
1098
1099will update the index with any files that you've modified or removed
1100and create a commit, all in one step.
1101
1102A number of commands are useful for keeping track of what you're
1103about to commit:
1104
1105-------------------------------------------------
1106$ git diff --cached # difference between HEAD and the index; what
Junio C Hamanocc13f552007-07-24 08:59:431107 # would be committed if you ran "commit" now.
Junio C Hamano8f62db92007-02-01 00:22:221108$ git diff # difference between the index file and your
1109 # working directory; changes that would not
1110 # be included if you ran "commit" now.
Junio C Hamano3d30fd52007-05-08 00:32:531111$ git diff HEAD # difference between HEAD and working tree; what
1112 # would be committed if you ran "commit -a" now.
Junio C Hamano8f62db92007-02-01 00:22:221113$ git status # a brief per-file summary of the above.
1114-------------------------------------------------
1115
Junio C Hamano35738e82008-01-07 07:55:461116You can also use linkgit:git-gui[1] to create commits, view changes in
Junio C Hamano4cd1c0e2007-08-06 04:39:141117the index and the working tree files, and individually select diff hunks
1118for inclusion in the index (by right-clicking on the diff hunk and
1119choosing "Stage Hunk For Commit").
1120
Junio C Hamano3d30fd52007-05-08 00:32:531121[[creating-good-commit-messages]]
Junio C Hamano12a3a232007-04-07 10:18:101122Creating good commit messages
Junio C Hamano8f62db92007-02-01 00:22:221123-----------------------------
1124
1125Though not required, it's a good idea to begin the commit message
1126with a single short (less than 50 character) line summarizing the
1127change, followed by a blank line and then a more thorough
1128description. Tools that turn commits into email, for example, use
1129the first line on the Subject line and the rest of the commit in the
1130body.
1131
Junio C Hamanoed7f4f62007-05-20 09:09:091132[[ignoring-files]]
1133Ignoring files
1134--------------
1135
1136A project will often generate files that you do 'not' want to track with git.
1137This typically includes files generated by a build process or temporary
1138backup files made by your editor. Of course, 'not' tracking files with git
Junio C Hamano5f9a6f02009-04-06 08:26:561139is just a matter of 'not' calling `git add` on them. But it quickly becomes
Junio C Hamanoed7f4f62007-05-20 09:09:091140annoying to have these untracked files lying around; e.g. they make
Junio C Hamanoea82cff2009-03-18 01:54:481141`git add .` practically useless, and they keep showing up in the output of
1142`git status`.
Junio C Hamanoed7f4f62007-05-20 09:09:091143
Junio C Hamano8b8b0f22007-08-26 22:10:261144You can tell git to ignore certain files by creating a file called .gitignore
1145in the top level of your working directory, with contents such as:
Junio C Hamanoed7f4f62007-05-20 09:09:091146
1147-------------------------------------------------
1148# Lines starting with '#' are considered comments.
Junio C Hamano8b8b0f22007-08-26 22:10:261149# Ignore any file named foo.txt.
Junio C Hamanoed7f4f62007-05-20 09:09:091150foo.txt
1151# Ignore (generated) html files,
1152*.html
1153# except foo.html which is maintained by hand.
1154!foo.html
1155# Ignore objects and archives.
1156*.[oa]
1157-------------------------------------------------
1158
Junio C Hamano35738e82008-01-07 07:55:461159See linkgit:gitignore[5] for a detailed explanation of the syntax. You can
Junio C Hamano8b8b0f22007-08-26 22:10:261160also place .gitignore files in other directories in your working tree, and they
1161will apply to those directories and their subdirectories. The `.gitignore`
1162files can be added to your repository like any other files (just run `git add
1163.gitignore` and `git commit`, as usual), which is convenient when the exclude
1164patterns (such as patterns matching build output files) would also make sense
1165for other users who clone your repository.
Junio C Hamanoed7f4f62007-05-20 09:09:091166
Junio C Hamano8b8b0f22007-08-26 22:10:261167If you wish the exclude patterns to affect only certain repositories
1168(instead of every repository for a given project), you may instead put
1169them in a file in your repository named .git/info/exclude, or in any file
1170specified by the `core.excludesfile` configuration variable. Some git
1171commands can also take exclude patterns directly on the command line.
Junio C Hamano35738e82008-01-07 07:55:461172See linkgit:gitignore[5] for the details.
Junio C Hamanoed7f4f62007-05-20 09:09:091173
Junio C Hamano3d30fd52007-05-08 00:32:531174[[how-to-merge]]
Junio C Hamano12a3a232007-04-07 10:18:101175How to merge
Junio C Hamano8f62db92007-02-01 00:22:221176------------
1177
1178You can rejoin two diverging branches of development using
Junio C Hamano35738e82008-01-07 07:55:461179linkgit:git-merge[1]:
Junio C Hamano8f62db92007-02-01 00:22:221180
1181-------------------------------------------------
1182$ git merge branchname
1183-------------------------------------------------
1184
1185merges the development in the branch "branchname" into the current
Junio C Hamano5706e0b2009-11-24 10:54:161186branch.
1187
1188A merge is made by combining the changes made in "branchname" and the
1189changes made up to the latest commit in your current branch since
1190their histories forked. The work tree is overwritten by the result of
1191the merge when this combining is done cleanly, or overwritten by a
1192half-merged results when this combining results in conflicts.
1193Therefore, if you have uncommitted changes touching the same files as
1194the ones impacted by the merge, Git will refuse to proceed. Most of
1195the time, you will want to commit your changes before you can merge,
1196and if you don't, then linkgit:git-stash[1] can take these changes
1197away while you're doing the merge, and reapply them afterwards.
1198
Junio C Hamano167b1382010-01-31 23:04:311199If the changes are independent enough, Git will automatically complete
Junio C Hamano5706e0b2009-11-24 10:54:161200the merge and commit the result (or reuse an existing commit in case
1201of <<fast-forwards,fast-forward>>, see below). On the other hand,
1202if there are conflicts--for example, if the same file is
Junio C Hamano8f62db92007-02-01 00:22:221203modified in two different ways in the remote branch and the local
1204branch--then you are warned; the output may look something like this:
1205
1206-------------------------------------------------
Junio C Hamanoc51fede2007-03-12 07:29:201207$ git merge next
1208 100% (4/4) done
1209Auto-merged file.txt
Junio C Hamano8f62db92007-02-01 00:22:221210CONFLICT (content): Merge conflict in file.txt
1211Automatic merge failed; fix conflicts and then commit the result.
1212-------------------------------------------------
1213
1214Conflict markers are left in the problematic files, and after
1215you resolve the conflicts manually, you can update the index
1216with the contents and run git commit, as you normally would when
1217creating a new file.
1218
1219If you examine the resulting commit using gitk, you will see that it
1220has two parents, one pointing to the top of the current branch, and
1221one to the top of the other branch.
1222
Junio C Hamano8f62db92007-02-01 00:22:221223[[resolving-a-merge]]
1224Resolving a merge
1225-----------------
1226
1227When a merge isn't resolved automatically, git leaves the index and
1228the working tree in a special state that gives you all the
1229information you need to help resolve the merge.
1230
1231Files with conflicts are marked specially in the index, so until you
Junio C Hamano35738e82008-01-07 07:55:461232resolve the problem and update the index, linkgit:git-commit[1] will
Junio C Hamanoaa83a7d2007-03-05 02:37:291233fail:
Junio C Hamano8f62db92007-02-01 00:22:221234
1235-------------------------------------------------
1236$ git commit
1237file.txt: needs merge
1238-------------------------------------------------
1239
Junio C Hamano35738e82008-01-07 07:55:461240Also, linkgit:git-status[1] will list those files as "unmerged", and the
Junio C Hamanoaa83a7d2007-03-05 02:37:291241files with conflicts will have conflict markers added, like this:
1242
1243-------------------------------------------------
1244<<<<<<< HEAD:file.txt
1245Hello world
1246=======
1247Goodbye
1248>>>>>>> 77976da35a11db4580b80ae27e8d65caf5208086:file.txt
1249-------------------------------------------------
1250
1251All you need to do is edit the files to resolve the conflicts, and then
1252
1253-------------------------------------------------
1254$ git add file.txt
1255$ git commit
1256-------------------------------------------------
1257
1258Note that the commit message will already be filled in for you with
1259some information about the merge. Normally you can just use this
1260default message unchanged, but you may add additional commentary of
1261your own if desired.
1262
1263The above is all you need to know to resolve a simple merge. But git
1264also provides more information to help resolve conflicts:
1265
Junio C Hamano3d30fd52007-05-08 00:32:531266[[conflict-resolution]]
Junio C Hamanoaa83a7d2007-03-05 02:37:291267Getting conflict-resolution help during a merge
1268~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Junio C Hamano8f62db92007-02-01 00:22:221269
1270All of the changes that git was able to merge automatically are
Junio C Hamano35738e82008-01-07 07:55:461271already added to the index file, so linkgit:git-diff[1] shows only
Junio C Hamanoaa83a7d2007-03-05 02:37:291272the conflicts. It uses an unusual syntax:
Junio C Hamano8f62db92007-02-01 00:22:221273
1274-------------------------------------------------
1275$ git diff
1276diff --cc file.txt
1277index 802992c,2b60207..0000000
1278--- a/file.txt
1279+++ b/file.txt
1280@@@ -1,1 -1,1 +1,5 @@@
1281++<<<<<<< HEAD:file.txt
1282 +Hello world
1283++=======
1284+ Goodbye
1285++>>>>>>> 77976da35a11db4580b80ae27e8d65caf5208086:file.txt
1286-------------------------------------------------
1287
Junio C Hamanocc13f552007-07-24 08:59:431288Recall that the commit which will be committed after we resolve this
Junio C Hamano8f62db92007-02-01 00:22:221289conflict will have two parents instead of the usual one: one parent
1290will be HEAD, the tip of the current branch; the other will be the
1291tip of the other branch, which is stored temporarily in MERGE_HEAD.
1292
Junio C Hamanoaa83a7d2007-03-05 02:37:291293During the merge, the index holds three versions of each file. Each of
1294these three "file stages" represents a different version of the file:
1295
1296-------------------------------------------------
1297$ git show :1:file.txt # the file in a common ancestor of both branches
Junio C Hamano6fb124c2008-06-13 10:04:011298$ git show :2:file.txt # the version from HEAD.
1299$ git show :3:file.txt # the version from MERGE_HEAD.
Junio C Hamanoaa83a7d2007-03-05 02:37:291300-------------------------------------------------
1301
Junio C Hamano6fb124c2008-06-13 10:04:011302When you ask linkgit:git-diff[1] to show the conflicts, it runs a
1303three-way diff between the conflicted merge results in the work tree with
1304stages 2 and 3 to show only hunks whose contents come from both sides,
1305mixed (in other words, when a hunk's merge results come only from stage 2,
1306that part is not conflicting and is not shown. Same for stage 3).
Junio C Hamanoaa83a7d2007-03-05 02:37:291307
1308The diff above shows the differences between the working-tree version of
1309file.txt and the stage 2 and stage 3 versions. So instead of preceding
1310each line by a single "+" or "-", it now uses two columns: the first
1311column is used for differences between the first parent and the working
1312directory copy, and the second for differences between the second parent
1313and the working directory copy. (See the "COMBINED DIFF FORMAT" section
Junio C Hamano35738e82008-01-07 07:55:461314of linkgit:git-diff-files[1] for a details of the format.)
Junio C Hamanoaa83a7d2007-03-05 02:37:291315
1316After resolving the conflict in the obvious way (but before updating the
1317index), the diff will look like:
Junio C Hamano8f62db92007-02-01 00:22:221318
1319-------------------------------------------------
1320$ git diff
1321diff --cc file.txt
1322index 802992c,2b60207..0000000
1323--- a/file.txt
1324+++ b/file.txt
1325@@@ -1,1 -1,1 +1,1 @@@
1326- Hello world
1327 -Goodbye
1328++Goodbye world
1329-------------------------------------------------
1330
1331This shows that our resolved version deleted "Hello world" from the
1332first parent, deleted "Goodbye" from the second parent, and added
1333"Goodbye world", which was previously absent from both.
1334
Junio C Hamanoaa83a7d2007-03-05 02:37:291335Some special diff options allow diffing the working directory against
1336any of these stages:
1337
1338-------------------------------------------------
1339$ git diff -1 file.txt # diff against stage 1
1340$ git diff --base file.txt # same as the above
1341$ git diff -2 file.txt # diff against stage 2
1342$ git diff --ours file.txt # same as the above
1343$ git diff -3 file.txt # diff against stage 3
1344$ git diff --theirs file.txt # same as the above.
1345-------------------------------------------------
1346
Junio C Hamanoba4b9282008-07-06 05:20:311347The linkgit:git-log[1] and linkgit:gitk[1] commands also provide special help
Junio C Hamanoaa83a7d2007-03-05 02:37:291348for merges:
Junio C Hamano8f62db92007-02-01 00:22:221349
1350-------------------------------------------------
1351$ git log --merge
Junio C Hamanoaa83a7d2007-03-05 02:37:291352$ gitk --merge
Junio C Hamano8f62db92007-02-01 00:22:221353-------------------------------------------------
1354
Junio C Hamanoaa83a7d2007-03-05 02:37:291355These will display all commits which exist only on HEAD or on
1356MERGE_HEAD, and which touch an unmerged file.
Junio C Hamano8f62db92007-02-01 00:22:221357
Junio C Hamano35738e82008-01-07 07:55:461358You may also use linkgit:git-mergetool[1], which lets you merge the
Junio C Hamano4fbdd442009-01-06 05:56:241359unmerged files using external tools such as Emacs or kdiff3.
Junio C Hamano3d30fd52007-05-08 00:32:531360
Junio C Hamanoaa83a7d2007-03-05 02:37:291361Each time you resolve the conflicts in a file and update the index:
Junio C Hamano8f62db92007-02-01 00:22:221362
1363-------------------------------------------------
1364$ git add file.txt
Junio C Hamano8f62db92007-02-01 00:22:221365-------------------------------------------------
1366
Junio C Hamanoaa83a7d2007-03-05 02:37:291367the different stages of that file will be "collapsed", after which
Junio C Hamano5f9a6f02009-04-06 08:26:561368`git diff` will (by default) no longer show diffs for that file.
Junio C Hamano8f62db92007-02-01 00:22:221369
1370[[undoing-a-merge]]
Junio C Hamano12a3a232007-04-07 10:18:101371Undoing a merge
Junio C Hamano8f62db92007-02-01 00:22:221372---------------
1373
1374If you get stuck and decide to just give up and throw the whole mess
1375away, you can always return to the pre-merge state with
1376
1377-------------------------------------------------
1378$ git reset --hard HEAD
1379-------------------------------------------------
1380
Junio C Hamanocc13f552007-07-24 08:59:431381Or, if you've already committed the merge that you want to throw away,
Junio C Hamano8f62db92007-02-01 00:22:221382
1383-------------------------------------------------
Junio C Hamanoaa83a7d2007-03-05 02:37:291384$ git reset --hard ORIG_HEAD
Junio C Hamano8f62db92007-02-01 00:22:221385-------------------------------------------------
1386
1387However, this last command can be dangerous in some cases--never
1388throw away a commit you have already committed if that commit may
1389itself have been merged into another branch, as doing so may confuse
1390further merges.
1391
Junio C Hamano3d30fd52007-05-08 00:32:531392[[fast-forwards]]
Junio C Hamano8f62db92007-02-01 00:22:221393Fast-forward merges
1394-------------------
1395
1396There is one special case not mentioned above, which is treated
1397differently. Normally, a merge results in a merge commit, with two
1398parents, one pointing at each of the two lines of development that
1399were merged.
1400
Junio C Hamano3d30fd52007-05-08 00:32:531401However, if the current branch is a descendant of the other--so every
1402commit present in the one is already contained in the other--then git
Junio C Hamano3f680f32009-11-16 02:10:541403just performs a "fast-forward"; the head of the current branch is moved
Junio C Hamano3d30fd52007-05-08 00:32:531404forward to point at the head of the merged-in branch, without any new
1405commits being created.
Junio C Hamano8f62db92007-02-01 00:22:221406
Junio C Hamano3d30fd52007-05-08 00:32:531407[[fixing-mistakes]]
Junio C Hamano8f62db92007-02-01 00:22:221408Fixing mistakes
1409---------------
1410
1411If you've messed up the working tree, but haven't yet committed your
1412mistake, you can return the entire working tree to the last committed
1413state with
1414
1415-------------------------------------------------
1416$ git reset --hard HEAD
1417-------------------------------------------------
1418
1419If you make a commit that you later wish you hadn't, there are two
1420fundamentally different ways to fix the problem:
1421
14221. You can create a new commit that undoes whatever was done
Junio C Hamano8c5802d2007-11-15 00:13:361423by the old commit. This is the correct thing if your
Junio C Hamano8f62db92007-02-01 00:22:221424mistake has already been made public.
1425
14262. You can go back and modify the old commit. You should
1427never do this if you have already made the history public;
1428git does not normally expect the "history" of a project to
1429change, and cannot correctly perform repeated merges from
1430a branch that has had its history changed.
1431
Junio C Hamano3d30fd52007-05-08 00:32:531432[[reverting-a-commit]]
Junio C Hamano8f62db92007-02-01 00:22:221433Fixing a mistake with a new commit
1434~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1435
1436Creating a new commit that reverts an earlier change is very easy;
Junio C Hamano35738e82008-01-07 07:55:461437just pass the linkgit:git-revert[1] command a reference to the bad
Junio C Hamano8f62db92007-02-01 00:22:221438commit; for example, to revert the most recent commit:
1439
1440-------------------------------------------------
1441$ git revert HEAD
1442-------------------------------------------------
1443
1444This will create a new commit which undoes the change in HEAD. You
1445will be given a chance to edit the commit message for the new commit.
1446
1447You can also revert an earlier change, for example, the next-to-last:
1448
1449-------------------------------------------------
1450$ git revert HEAD^
1451-------------------------------------------------
1452
1453In this case git will attempt to undo the old change while leaving
1454intact any changes made since then. If more recent changes overlap
1455with the changes to be reverted, then you will be asked to fix
1456conflicts manually, just as in the case of <<resolving-a-merge,
1457resolving a merge>>.
1458
Junio C Hamanoce3650e2007-11-26 04:20:111459[[fixing-a-mistake-by-rewriting-history]]
1460Fixing a mistake by rewriting history
Junio C Hamano8f62db92007-02-01 00:22:221461~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1462
1463If the problematic commit is the most recent commit, and you have not
1464yet made that commit public, then you may just
Junio C Hamano5f9a6f02009-04-06 08:26:561465<<undoing-a-merge,destroy it using `git reset`>>.
Junio C Hamano8f62db92007-02-01 00:22:221466
1467Alternatively, you
1468can edit the working directory and update the index to fix your
1469mistake, just as if you were going to <<how-to-make-a-commit,create a
1470new commit>>, then run
1471
1472-------------------------------------------------
1473$ git commit --amend
1474-------------------------------------------------
1475
1476which will replace the old commit by a new commit incorporating your
1477changes, giving you a chance to edit the old commit message first.
1478
1479Again, you should never do this to a commit that may already have
Junio C Hamano35738e82008-01-07 07:55:461480been merged into another branch; use linkgit:git-revert[1] instead in
Junio C Hamano8f62db92007-02-01 00:22:221481that case.
1482
Junio C Hamanoce3650e2007-11-26 04:20:111483It is also possible to replace commits further back in the history, but
Junio C Hamano8f62db92007-02-01 00:22:221484this is an advanced topic to be left for
1485<<cleaning-up-history,another chapter>>.
1486
Junio C Hamano3d30fd52007-05-08 00:32:531487[[checkout-of-path]]
Junio C Hamano8f62db92007-02-01 00:22:221488Checking out an old version of a file
1489~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1490
1491In the process of undoing a previous bad change, you may find it
1492useful to check out an older version of a particular file using
Junio C Hamano5f9a6f02009-04-06 08:26:561493linkgit:git-checkout[1]. We've used `git checkout` before to switch
Junio C Hamano8f62db92007-02-01 00:22:221494branches, but it has quite different behavior if it is given a path
1495name: the command
1496
1497-------------------------------------------------
1498$ git checkout HEAD^ path/to/file
1499-------------------------------------------------
1500
1501replaces path/to/file by the contents it had in the commit HEAD^, and
1502also updates the index to match. It does not change branches.
1503
1504If you just want to look at an old version of the file, without
1505modifying the working directory, you can do that with
Junio C Hamano35738e82008-01-07 07:55:461506linkgit:git-show[1]:
Junio C Hamano8f62db92007-02-01 00:22:221507
1508-------------------------------------------------
Junio C Hamanoc51fede2007-03-12 07:29:201509$ git show HEAD^:path/to/file
Junio C Hamano8f62db92007-02-01 00:22:221510-------------------------------------------------
1511
1512which will display the given version of the file.
1513
Junio C Hamano4cd1c0e2007-08-06 04:39:141514[[interrupted-work]]
1515Temporarily setting aside work in progress
1516~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1517
1518While you are in the middle of working on something complicated, you
1519find an unrelated but obvious and trivial bug. You would like to fix it
Junio C Hamano35738e82008-01-07 07:55:461520before continuing. You can use linkgit:git-stash[1] to save the current
Junio C Hamano4cd1c0e2007-08-06 04:39:141521state of your work, and after fixing the bug (or, optionally after doing
1522so on a different branch and then coming back), unstash the
1523work-in-progress changes.
1524
1525------------------------------------------------
Junio C Hamano78502452009-02-04 16:53:501526$ git stash save "work in progress for foo feature"
Junio C Hamano4cd1c0e2007-08-06 04:39:141527------------------------------------------------
1528
1529This command will save your changes away to the `stash`, and
1530reset your working tree and the index to match the tip of your
1531current branch. Then you can make your fix as usual.
1532
1533------------------------------------------------
1534... edit and test ...
1535$ git commit -a -m "blorpl: typofix"
1536------------------------------------------------
1537
1538After that, you can go back to what you were working on with
Junio C Hamano7d3275e2009-05-31 21:53:301539`git stash pop`:
Junio C Hamano4cd1c0e2007-08-06 04:39:141540
1541------------------------------------------------
Junio C Hamano7d3275e2009-05-31 21:53:301542$ git stash pop
Junio C Hamano4cd1c0e2007-08-06 04:39:141543------------------------------------------------
1544
1545
Junio C Hamano3d30fd52007-05-08 00:32:531546[[ensuring-good-performance]]
Junio C Hamano8f62db92007-02-01 00:22:221547Ensuring good performance
1548-------------------------
1549
1550On large repositories, git depends on compression to keep the history
Junio C Hamano764a6672007-10-23 01:23:311551information from taking up too much space on disk or in memory.
Junio C Hamano8f62db92007-02-01 00:22:221552
1553This compression is not performed automatically. Therefore you
Junio C Hamano35738e82008-01-07 07:55:461554should occasionally run linkgit:git-gc[1]:
Junio C Hamano8f62db92007-02-01 00:22:221555
1556-------------------------------------------------
1557$ git gc
1558-------------------------------------------------
1559
1560to recompress the archive. This can be very time-consuming, so
Junio C Hamano5f9a6f02009-04-06 08:26:561561you may prefer to run `git gc` when you are not doing other work.
Junio C Hamano8f62db92007-02-01 00:22:221562
Junio C Hamano3d30fd52007-05-08 00:32:531563
1564[[ensuring-reliability]]
Junio C Hamano8f62db92007-02-01 00:22:221565Ensuring reliability
1566--------------------
1567
Junio C Hamano3d30fd52007-05-08 00:32:531568[[checking-for-corruption]]
Junio C Hamano8f62db92007-02-01 00:22:221569Checking the repository for corruption
1570~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1571
Junio C Hamano35738e82008-01-07 07:55:461572The linkgit:git-fsck[1] command runs a number of self-consistency checks
Junio C Hamano8f62db92007-02-01 00:22:221573on the repository, and reports on any problems. This may take some
1574time. The most common warning by far is about "dangling" objects:
1575
1576-------------------------------------------------
1577$ git fsck
1578dangling commit 7281251ddd2a61e38657c827739c57015671a6b3
1579dangling commit 2706a059f258c6b245f298dc4ff2ccd30ec21a63
1580dangling commit 13472b7c4b80851a1bc551779171dcb03655e9b5
1581dangling blob 218761f9d90712d37a9c5e36f406f92202db07eb
1582dangling commit bf093535a34a4d35731aa2bd90fe6b176302f14f
1583dangling commit 8e4bec7f2ddaa268bef999853c25755452100f8e
1584dangling tree d50bb86186bf27b681d25af89d3b5b68382e4085
1585dangling tree b24c2473f1fd3d91352a624795be026d64c8841f
1586...
1587-------------------------------------------------
1588
Junio C Hamano3d30fd52007-05-08 00:32:531589Dangling objects are not a problem. At worst they may take up a little
Junio C Hamano2a8f6dc2007-07-09 08:48:381590extra disk space. They can sometimes provide a last-resort method for
Junio C Hamanoa9aee782008-04-23 16:09:201591recovering lost work--see <<dangling-objects>> for details.
Junio C Hamanoce3650e2007-11-26 04:20:111592
Junio C Hamano3d30fd52007-05-08 00:32:531593[[recovering-lost-changes]]
Junio C Hamano8f62db92007-02-01 00:22:221594Recovering lost changes
1595~~~~~~~~~~~~~~~~~~~~~~~
1596
Junio C Hamano3d30fd52007-05-08 00:32:531597[[reflogs]]
Junio C Hamano8f62db92007-02-01 00:22:221598Reflogs
1599^^^^^^^
1600
Junio C Hamano35738e82008-01-07 07:55:461601Say you modify a branch with `linkgit:git-reset[1] --hard`, and then
Junio C Hamano8f62db92007-02-01 00:22:221602realize that the branch was the only reference you had to that point in
1603history.
1604
1605Fortunately, git also keeps a log, called a "reflog", of all the
1606previous values of each branch. So in this case you can still find the
Junio C Hamanoa77a5132007-06-08 16:13:441607old history using, for example,
Junio C Hamano8f62db92007-02-01 00:22:221608
1609-------------------------------------------------
1610$ git log master@{1}
1611-------------------------------------------------
1612
Junio C Hamano63777e22007-11-17 20:52:161613This lists the commits reachable from the previous version of the
1614"master" branch head. This syntax can be used with any git command
1615that accepts a commit, not just with git log. Some other examples:
Junio C Hamano8f62db92007-02-01 00:22:221616
1617-------------------------------------------------
1618$ git show master@{2} # See where the branch pointed 2,
1619$ git show master@{3} # 3, ... changes ago.
1620$ gitk master@{yesterday} # See where it pointed yesterday,
1621$ gitk master@{"1 week ago"} # ... or last week
Junio C Hamano3d30fd52007-05-08 00:32:531622$ git log --walk-reflogs master # show reflog entries for master
Junio C Hamano8f62db92007-02-01 00:22:221623-------------------------------------------------
1624
Junio C Hamano3d30fd52007-05-08 00:32:531625A separate reflog is kept for the HEAD, so
1626
1627-------------------------------------------------
1628$ git show HEAD@{"1 week ago"}
1629-------------------------------------------------
1630
1631will show what HEAD pointed to one week ago, not what the current branch
1632pointed to one week ago. This allows you to see the history of what
1633you've checked out.
1634
Junio C Hamano8f62db92007-02-01 00:22:221635The reflogs are kept by default for 30 days, after which they may be
Junio C Hamano35738e82008-01-07 07:55:461636pruned. See linkgit:git-reflog[1] and linkgit:git-gc[1] to learn
Junio C Hamano8f62db92007-02-01 00:22:221637how to control this pruning, and see the "SPECIFYING REVISIONS"
Junio C Hamanoc27b7332010-10-14 04:37:281638section of linkgit:gitrevisions[7] for details.
Junio C Hamano8f62db92007-02-01 00:22:221639
1640Note that the reflog history is very different from normal git history.
1641While normal history is shared by every repository that works on the
1642same project, the reflog history is not shared: it tells you only about
1643how the branches in your local repository have changed over time.
1644
Junio C Hamano3d30fd52007-05-08 00:32:531645[[dangling-object-recovery]]
Junio C Hamano8f62db92007-02-01 00:22:221646Examining dangling objects
1647^^^^^^^^^^^^^^^^^^^^^^^^^^
1648
Junio C Hamano3d30fd52007-05-08 00:32:531649In some situations the reflog may not be able to save you. For example,
1650suppose you delete a branch, then realize you need the history it
1651contained. The reflog is also deleted; however, if you have not yet
1652pruned the repository, then you may still be able to find the lost
Junio C Hamano5f9a6f02009-04-06 08:26:561653commits in the dangling objects that `git fsck` reports. See
Junio C Hamano3d30fd52007-05-08 00:32:531654<<dangling-objects>> for the details.
Junio C Hamano8f62db92007-02-01 00:22:221655
1656-------------------------------------------------
1657$ git fsck
1658dangling commit 7281251ddd2a61e38657c827739c57015671a6b3
1659dangling commit 2706a059f258c6b245f298dc4ff2ccd30ec21a63
1660dangling commit 13472b7c4b80851a1bc551779171dcb03655e9b5
1661...
1662-------------------------------------------------
1663
Junio C Hamano39381a72007-02-02 07:35:151664You can examine
Junio C Hamano8f62db92007-02-01 00:22:221665one of those dangling commits with, for example,
1666
1667------------------------------------------------
1668$ gitk 7281251ddd --not --all
1669------------------------------------------------
1670
1671which does what it sounds like: it says that you want to see the commit
1672history that is described by the dangling commit(s), but not the
1673history that is described by all your existing branches and tags. Thus
1674you get exactly the history reachable from that commit that is lost.
1675(And notice that it might not be just one commit: we only report the
1676"tip of the line" as being dangling, but there might be a whole deep
Junio C Hamanodb911ee2007-02-28 08:13:521677and complex commit history that was dropped.)
Junio C Hamano8f62db92007-02-01 00:22:221678
1679If you decide you want the history back, you can always create a new
1680reference pointing to it, for example, a new branch:
1681
1682------------------------------------------------
Junio C Hamanoa77a5132007-06-08 16:13:441683$ git branch recovered-branch 7281251ddd
Junio C Hamano8f62db92007-02-01 00:22:221684------------------------------------------------
1685
Junio C Hamano3d30fd52007-05-08 00:32:531686Other types of dangling objects (blobs and trees) are also possible, and
1687dangling objects can arise in other situations.
Junio C Hamano8f62db92007-02-01 00:22:221688
Junio C Hamano3d30fd52007-05-08 00:32:531689
1690[[sharing-development]]
Junio C Hamano8f62db92007-02-01 00:22:221691Sharing development with others
1692===============================
1693
Junio C Hamanoec87f522008-12-10 08:35:251694[[getting-updates-With-git-pull]]
Junio C Hamano5f9a6f02009-04-06 08:26:561695Getting updates with git pull
Junio C Hamano8f62db92007-02-01 00:22:221696-----------------------------
1697
Junio C Hamano5706e0b2009-11-24 10:54:161698After you clone a repository and commit a few changes of your own, you
Junio C Hamano8f62db92007-02-01 00:22:221699may wish to check the original repository for updates and merge them
1700into your own work.
1701
Junio C Hamanoec87f522008-12-10 08:35:251702We have already seen <<Updating-a-repository-With-git-fetch,how to
Junio C Hamano35738e82008-01-07 07:55:461703keep remote tracking branches up to date>> with linkgit:git-fetch[1],
Junio C Hamano8f62db92007-02-01 00:22:221704and how to merge two branches. So you can merge in changes from the
1705original repository's master branch with:
1706
1707-------------------------------------------------
1708$ git fetch
1709$ git merge origin/master
1710-------------------------------------------------
1711
Junio C Hamano35738e82008-01-07 07:55:461712However, the linkgit:git-pull[1] command provides a way to do this in
Junio C Hamano8f62db92007-02-01 00:22:221713one step:
1714
1715-------------------------------------------------
1716$ git pull origin master
1717-------------------------------------------------
1718
Junio C Hamano4cd1c0e2007-08-06 04:39:141719In fact, if you have "master" checked out, then by default "git pull"
1720merges from the HEAD branch of the origin repository. So often you can
1721accomplish the above with just a simple
Junio C Hamano8f62db92007-02-01 00:22:221722
1723-------------------------------------------------
1724$ git pull
1725-------------------------------------------------
1726
Junio C Hamano4cd1c0e2007-08-06 04:39:141727More generally, a branch that is created from a remote branch will pull
1728by default from that branch. See the descriptions of the
1729branch.<name>.remote and branch.<name>.merge options in
Junio C Hamano35738e82008-01-07 07:55:461730linkgit:git-config[1], and the discussion of the `--track` option in
1731linkgit:git-checkout[1], to learn how to control these defaults.
Junio C Hamano8f62db92007-02-01 00:22:221732
1733In addition to saving you keystrokes, "git pull" also helps you by
1734producing a default commit message documenting the branch and
1735repository that you pulled from.
1736
1737(But note that no such commit will be created in the case of a
Junio C Hamano3f680f32009-11-16 02:10:541738<<fast-forwards,fast-forward>>; instead, your branch will just be
Junio C Hamanodb911ee2007-02-28 08:13:521739updated to point to the latest commit from the upstream branch.)
Junio C Hamano8f62db92007-02-01 00:22:221740
Junio C Hamano5f9a6f02009-04-06 08:26:561741The `git pull` command can also be given "." as the "remote" repository,
Junio C Hamano8f62db92007-02-01 00:22:221742in which case it just merges in a branch from the current repository; so
1743the commands
1744
1745-------------------------------------------------
1746$ git pull . branch
1747$ git merge branch
1748-------------------------------------------------
1749
1750are roughly equivalent. The former is actually very commonly used.
1751
Junio C Hamano3d30fd52007-05-08 00:32:531752[[submitting-patches]]
Junio C Hamano8f62db92007-02-01 00:22:221753Submitting patches to a project
1754-------------------------------
1755
1756If you just have a few changes, the simplest way to submit them may
1757just be to send them as patches in email:
1758
Junio C Hamano35738e82008-01-07 07:55:461759First, use linkgit:git-format-patch[1]; for example:
Junio C Hamano8f62db92007-02-01 00:22:221760
1761-------------------------------------------------
1762$ git format-patch origin
1763-------------------------------------------------
1764
1765will produce a numbered series of files in the current directory, one
1766for each patch in the current branch but not in origin/HEAD.
1767
1768You can then import these into your mail client and send them by
1769hand. However, if you have a lot to send at once, you may prefer to
Junio C Hamano35738e82008-01-07 07:55:461770use the linkgit:git-send-email[1] script to automate the process.
Junio C Hamano8f62db92007-02-01 00:22:221771Consult the mailing list for your project first to determine how they
1772prefer such patches be handled.
1773
Junio C Hamano3d30fd52007-05-08 00:32:531774[[importing-patches]]
Junio C Hamano8f62db92007-02-01 00:22:221775Importing patches to a project
1776------------------------------
1777
Junio C Hamano35738e82008-01-07 07:55:461778Git also provides a tool called linkgit:git-am[1] (am stands for
Junio C Hamano8f62db92007-02-01 00:22:221779"apply mailbox"), for importing such an emailed series of patches.
1780Just save all of the patch-containing messages, in order, into a
1781single mailbox file, say "patches.mbox", then run
1782
1783-------------------------------------------------
1784$ git am -3 patches.mbox
1785-------------------------------------------------
1786
1787Git will apply each patch in order; if any conflicts are found, it
1788will stop, and you can fix the conflicts as described in
1789"<<resolving-a-merge,Resolving a merge>>". (The "-3" option tells
1790git to perform a merge; if you would prefer it just to abort and
1791leave your tree and index untouched, you may omit that option.)
1792
1793Once the index is updated with the results of the conflict
1794resolution, instead of creating a new commit, just run
1795
1796-------------------------------------------------
1797$ git am --resolved
1798-------------------------------------------------
1799
1800and git will create the commit for you and continue applying the
1801remaining patches from the mailbox.
1802
1803The final result will be a series of commits, one for each patch in
1804the original mailbox, with authorship and commit log message each
1805taken from the message containing each patch.
1806
Junio C Hamano75485c82007-05-19 04:20:331807[[public-repositories]]
1808Public git repositories
1809-----------------------
Junio C Hamano8f62db92007-02-01 00:22:221810
Junio C Hamano8b8b0f22007-08-26 22:10:261811Another way to submit changes to a project is to tell the maintainer
1812of that project to pull the changes from your repository using
Junio C Hamanoec87f522008-12-10 08:35:251813linkgit:git-pull[1]. In the section "<<getting-updates-With-git-pull,
Junio C Hamano5f9a6f02009-04-06 08:26:561814Getting updates with `git pull`>>" we described this as a way to get
Junio C Hamano8b8b0f22007-08-26 22:10:261815updates from the "main" repository, but it works just as well in the
1816other direction.
Junio C Hamano8f62db92007-02-01 00:22:221817
Junio C Hamano75485c82007-05-19 04:20:331818If you and the maintainer both have accounts on the same machine, then
1819you can just pull changes from each other's repositories directly;
Junio C Hamano2a8f6dc2007-07-09 08:48:381820commands that accept repository URLs as arguments will also accept a
Junio C Hamano75485c82007-05-19 04:20:331821local directory name:
Junio C Hamano8f62db92007-02-01 00:22:221822
1823-------------------------------------------------
1824$ git clone /path/to/repository
1825$ git pull /path/to/other/repository
1826-------------------------------------------------
1827
Junio C Hamano764a6672007-10-23 01:23:311828or an ssh URL:
Junio C Hamano2a8f6dc2007-07-09 08:48:381829
1830-------------------------------------------------
1831$ git clone ssh://yourhost/~you/repository
1832-------------------------------------------------
1833
1834For projects with few developers, or for synchronizing a few private
1835repositories, this may be all you need.
1836
Junio C Hamano75485c82007-05-19 04:20:331837However, the more common way to do this is to maintain a separate public
1838repository (usually on a different host) for others to pull changes
1839from. This is usually more convenient, and allows you to cleanly
1840separate private work in progress from publicly visible work.
Junio C Hamano8f62db92007-02-01 00:22:221841
1842You will continue to do your day-to-day work in your personal
1843repository, but periodically "push" changes from your personal
1844repository into your public repository, allowing other developers to
1845pull from that repository. So the flow of changes, in a situation
1846where there is one other developer with a public repository, looks
1847like this:
1848
1849 you push
1850 your personal repo ------------------> your public repo
Junio C Hamanoa77a5132007-06-08 16:13:441851^ |
Junio C Hamano8f62db92007-02-01 00:22:221852| |
1853| you pull | they pull
1854| |
1855| |
1856 | they push V
1857 their public repo <------------------- their repo
1858
Junio C Hamano2a8f6dc2007-07-09 08:48:381859We explain how to do this in the following sections.
1860
Junio C Hamano75485c82007-05-19 04:20:331861[[setting-up-a-public-repository]]
1862Setting up a public repository
1863~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1864
1865Assume your personal repository is in the directory ~/proj. We
Junio C Hamano5f9a6f02009-04-06 08:26:561866first create a new clone of the repository and tell `git daemon` that it
Junio C Hamano75485c82007-05-19 04:20:331867is meant to be public:
Junio C Hamano8f62db92007-02-01 00:22:221868
1869-------------------------------------------------
Junio C Hamano91d44c52007-05-09 07:16:071870$ git clone --bare ~/proj proj.git
Junio C Hamano75485c82007-05-19 04:20:331871$ touch proj.git/git-daemon-export-ok
Junio C Hamano8f62db92007-02-01 00:22:221872-------------------------------------------------
1873
Junio C Hamano91d44c52007-05-09 07:16:071874The resulting directory proj.git contains a "bare" git repository--it is
Junio C Hamano75485c82007-05-19 04:20:331875just the contents of the ".git" directory, without any files checked out
1876around it.
Junio C Hamano8f62db92007-02-01 00:22:221877
Junio C Hamano3d30fd52007-05-08 00:32:531878Next, copy proj.git to the server where you plan to host the
Junio C Hamano8f62db92007-02-01 00:22:221879public repository. You can use scp, rsync, or whatever is most
1880convenient.
1881
Junio C Hamano75485c82007-05-19 04:20:331882[[exporting-via-git]]
1883Exporting a git repository via the git protocol
1884~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1885
1886This is the preferred method.
1887
1888If someone else administers the server, they should tell you what
Junio C Hamano764a6672007-10-23 01:23:311889directory to put the repository in, and what git:// URL it will appear
Junio C Hamano75485c82007-05-19 04:20:331890at. You can then skip to the section
Junio C Hamano8f62db92007-02-01 00:22:221891"<<pushing-changes-to-a-public-repository,Pushing changes to a public
1892repository>>", below.
1893
Junio C Hamano35738e82008-01-07 07:55:461894Otherwise, all you need to do is start linkgit:git-daemon[1]; it will
Junio C Hamano75485c82007-05-19 04:20:331895listen on port 9418. By default, it will allow access to any directory
1896that looks like a git directory and contains the magic file
Junio C Hamano5f9a6f02009-04-06 08:26:561897git-daemon-export-ok. Passing some directory paths as `git daemon`
Junio C Hamano75485c82007-05-19 04:20:331898arguments will further restrict the exports to those paths.
1899
Junio C Hamano5f9a6f02009-04-06 08:26:561900You can also run `git daemon` as an inetd service; see the
Junio C Hamano35738e82008-01-07 07:55:461901linkgit:git-daemon[1] man page for details. (See especially the
Junio C Hamano75485c82007-05-19 04:20:331902examples section.)
Junio C Hamano8f62db92007-02-01 00:22:221903
1904[[exporting-via-http]]
1905Exporting a git repository via http
Junio C Hamano75485c82007-05-19 04:20:331906~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Junio C Hamano8f62db92007-02-01 00:22:221907
1908The git protocol gives better performance and reliability, but on a
1909host with a web server set up, http exports may be simpler to set up.
1910
1911All you need to do is place the newly created bare git repository in
1912a directory that is exported by the web server, and make some
1913adjustments to give web clients some extra information they need:
1914
1915-------------------------------------------------
1916$ mv proj.git /home/you/public_html/proj.git
1917$ cd proj.git
Junio C Hamano3d30fd52007-05-08 00:32:531918$ git --bare update-server-info
Junio C Hamanoc96fb5a2008-08-12 06:59:381919$ mv hooks/post-update.sample hooks/post-update
Junio C Hamano8f62db92007-02-01 00:22:221920-------------------------------------------------
1921
1922(For an explanation of the last two lines, see
Junio C Hamanofce7c7e2008-07-02 03:06:381923linkgit:git-update-server-info[1] and linkgit:githooks[5].)
Junio C Hamano8f62db92007-02-01 00:22:221924
Junio C Hamano764a6672007-10-23 01:23:311925Advertise the URL of proj.git. Anybody else should then be able to
1926clone or pull from that URL, for example with a command line like:
Junio C Hamano8f62db92007-02-01 00:22:221927
1928-------------------------------------------------
1929$ git clone http://yourserver.com/~you/proj.git
1930-------------------------------------------------
1931
1932(See also
1933link:howto/setup-git-server-over-http.txt[setup-git-server-over-http]
1934for a slightly more sophisticated setup using WebDAV which also
1935allows pushing over http.)
1936
Junio C Hamano8f62db92007-02-01 00:22:221937[[pushing-changes-to-a-public-repository]]
1938Pushing changes to a public repository
Junio C Hamano75485c82007-05-19 04:20:331939~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Junio C Hamano8f62db92007-02-01 00:22:221940
Junio C Hamano75485c82007-05-19 04:20:331941Note that the two techniques outlined above (exporting via
Junio C Hamano8f62db92007-02-01 00:22:221942<<exporting-via-http,http>> or <<exporting-via-git,git>>) allow other
1943maintainers to fetch your latest changes, but they do not allow write
1944access, which you will need to update the public repository with the
1945latest changes created in your private repository.
1946
Junio C Hamano35738e82008-01-07 07:55:461947The simplest way to do this is using linkgit:git-push[1] and ssh; to
Junio C Hamano8f62db92007-02-01 00:22:221948update the remote branch named "master" with the latest state of your
1949branch named "master", run
1950
1951-------------------------------------------------
1952$ git push ssh://yourserver.com/~you/proj.git master:master
1953-------------------------------------------------
1954
1955or just
1956
1957-------------------------------------------------
1958$ git push ssh://yourserver.com/~you/proj.git master
1959-------------------------------------------------
1960
Junio C Hamano5f9a6f02009-04-06 08:26:561961As with `git fetch`, `git push` will complain if this does not result in a
Junio C Hamano3f680f32009-11-16 02:10:541962<<fast-forwards,fast-forward>>; see the following section for details on
Junio C Hamanoce3650e2007-11-26 04:20:111963handling this case.
Junio C Hamano8f62db92007-02-01 00:22:221964
Junio C Hamano2a8f6dc2007-07-09 08:48:381965Note that the target of a "push" is normally a
1966<<def_bare_repository,bare>> repository. You can also push to a
1967repository that has a checked-out working tree, but the working tree
1968will not be updated by the push. This may lead to unexpected results if
1969the branch you push to is the currently checked-out branch!
1970
Junio C Hamano5f9a6f02009-04-06 08:26:561971As with `git fetch`, you may also set up configuration options to
Junio C Hamano8f62db92007-02-01 00:22:221972save typing; so, for example, after
1973
1974-------------------------------------------------
Junio C Hamano3d30fd52007-05-08 00:32:531975$ cat >>.git/config <<EOF
Junio C Hamano8f62db92007-02-01 00:22:221976[remote "public-repo"]
1977url = ssh://yourserver.com/~you/proj.git
1978EOF
1979-------------------------------------------------
1980
1981you should be able to perform the above push with just
1982
1983-------------------------------------------------
1984$ git push public-repo master
1985-------------------------------------------------
1986
1987See the explanations of the remote.<name>.url, branch.<name>.remote,
Junio C Hamano35738e82008-01-07 07:55:461988and remote.<name>.push options in linkgit:git-config[1] for
Junio C Hamano8f62db92007-02-01 00:22:221989details.
1990
Junio C Hamanoce3650e2007-11-26 04:20:111991[[forcing-push]]
1992What to do when a push fails
1993~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1994
Junio C Hamano3f680f32009-11-16 02:10:541995If a push would not result in a <<fast-forwards,fast-forward>> of the
Junio C Hamanoce3650e2007-11-26 04:20:111996remote branch, then it will fail with an error like:
1997
1998-------------------------------------------------
1999error: remote 'refs/heads/master' is not an ancestor of
2000 local 'refs/heads/master'.
2001 Maybe you are not up-to-date and need to pull first?
2002error: failed to push to 'ssh://yourserver.com/~you/proj.git'
2003-------------------------------------------------
2004
2005This can happen, for example, if you:
2006
Junio C Hamano5f9a6f02009-04-06 08:26:562007- use `git reset --hard` to remove already-published commits, or
2008- use `git commit --amend` to replace already-published commits
Junio C Hamanoce3650e2007-11-26 04:20:112009 (as in <<fixing-a-mistake-by-rewriting-history>>), or
Junio C Hamano5f9a6f02009-04-06 08:26:562010- use `git rebase` to rebase any already-published commits (as
Junio C Hamanoce3650e2007-11-26 04:20:112011 in <<using-git-rebase>>).
2012
Junio C Hamano5f9a6f02009-04-06 08:26:562013You may force `git push` to perform the update anyway by preceding the
Junio C Hamanoce3650e2007-11-26 04:20:112014branch name with a plus sign:
2015
2016-------------------------------------------------
2017$ git push ssh://yourserver.com/~you/proj.git +master
2018-------------------------------------------------
2019
2020Normally whenever a branch head in a public repository is modified, it
Junio C Hamano878cc1e2007-12-14 08:35:132021is modified to point to a descendant of the commit that it pointed to
Junio C Hamanoce3650e2007-11-26 04:20:112022before. By forcing a push in this situation, you break that convention.
Junio C Hamanoec87f522008-12-10 08:35:252023(See <<problems-With-rewriting-history>>.)
Junio C Hamanoce3650e2007-11-26 04:20:112024
2025Nevertheless, this is a common practice for people that need a simple
2026way to publish a work-in-progress patch series, and it is an acceptable
2027compromise as long as you warn other developers that this is how you
2028intend to manage the branch.
2029
2030It's also possible for a push to fail in this way when other people have
2031the right to push to the same repository. In that case, the correct
Junio C Hamanod32738e2008-07-09 19:53:422032solution is to retry the push after first updating your work: either by a
2033pull, or by a fetch followed by a rebase; see the
Junio C Hamanoce3650e2007-11-26 04:20:112034<<setting-up-a-shared-repository,next section>> and
Junio C Hamanofce7c7e2008-07-02 03:06:382035linkgit:gitcvs-migration[7] for more.
Junio C Hamanoce3650e2007-11-26 04:20:112036
Junio C Hamano3d30fd52007-05-08 00:32:532037[[setting-up-a-shared-repository]]
Junio C Hamano8f62db92007-02-01 00:22:222038Setting up a shared repository
Junio C Hamano75485c82007-05-19 04:20:332039~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Junio C Hamano8f62db92007-02-01 00:22:222040
2041Another way to collaborate is by using a model similar to that
2042commonly used in CVS, where several developers with special rights
2043all push to and pull from a single shared repository. See
Junio C Hamanofce7c7e2008-07-02 03:06:382044linkgit:gitcvs-migration[7] for instructions on how to
Junio C Hamano8f62db92007-02-01 00:22:222045set this up.
2046
Junio C Hamanoed7f4f62007-05-20 09:09:092047However, while there is nothing wrong with git's support for shared
2048repositories, this mode of operation is not generally recommended,
2049simply because the mode of collaboration that git supports--by
2050exchanging patches and pulling from public repositories--has so many
2051advantages over the central shared repository:
2052
2053- Git's ability to quickly import and merge patches allows a
2054 single maintainer to process incoming changes even at very
Junio C Hamano5f9a6f02009-04-06 08:26:562055 high rates. And when that becomes too much, `git pull` provides
Junio C Hamanoed7f4f62007-05-20 09:09:092056 an easy way for that maintainer to delegate this job to other
2057 maintainers while still allowing optional review of incoming
2058 changes.
2059- Since every developer's repository has the same complete copy
2060 of the project history, no repository is special, and it is
2061 trivial for another developer to take over maintenance of a
2062 project, either by mutual agreement, or because a maintainer
2063 becomes unresponsive or difficult to work with.
2064- The lack of a central group of "committers" means there is
2065 less need for formal decisions about who is "in" and who is
2066 "out".
2067
Junio C Hamano3d30fd52007-05-08 00:32:532068[[setting-up-gitweb]]
Junio C Hamano75485c82007-05-19 04:20:332069Allowing web browsing of a repository
2070~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Junio C Hamano8f62db92007-02-01 00:22:222071
2072The gitweb cgi script provides users an easy way to browse your
2073project's files and history without having to install git; see the file
Junio C Hamano4c6aa8a2007-04-04 08:56:372074gitweb/INSTALL in the git source tree for instructions on setting it up.
Junio C Hamano8f62db92007-02-01 00:22:222075
Junio C Hamano3d30fd52007-05-08 00:32:532076[[sharing-development-examples]]
Junio C Hamano8f62db92007-02-01 00:22:222077Examples
2078--------
2079
Junio C Hamano75485c82007-05-19 04:20:332080[[maintaining-topic-branches]]
2081Maintaining topic branches for a Linux subsystem maintainer
2082~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2083
2084This describes how Tony Luck uses git in his role as maintainer of the
2085IA64 architecture for the Linux kernel.
2086
2087He uses two public branches:
2088
2089 - A "test" tree into which patches are initially placed so that they
2090 can get some exposure when integrated with other ongoing development.
2091 This tree is available to Andrew for pulling into -mm whenever he
2092 wants.
2093
2094 - A "release" tree into which tested patches are moved for final sanity
2095 checking, and as a vehicle to send them upstream to Linus (by sending
2096 him a "please pull" request.)
2097
2098He also uses a set of temporary branches ("topic branches"), each
2099containing a logical grouping of patches.
2100
2101To set this up, first create your work tree by cloning Linus's public
2102tree:
2103
2104-------------------------------------------------
2105$ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git work
2106$ cd work
2107-------------------------------------------------
2108
2109Linus's tree will be stored in the remote branch named origin/master,
Junio C Hamano35738e82008-01-07 07:55:462110and can be updated using linkgit:git-fetch[1]; you can track other
2111public trees using linkgit:git-remote[1] to set up a "remote" and
2112linkgit:git-fetch[1] to keep them up-to-date; see
Junio C Hamano8b8b0f22007-08-26 22:10:262113<<repositories-and-branches>>.
Junio C Hamano75485c82007-05-19 04:20:332114
2115Now create the branches in which you are going to work; these start out
2116at the current tip of origin/master branch, and should be set up (using
Junio C Hamano35738e82008-01-07 07:55:462117the --track option to linkgit:git-branch[1]) to merge changes in from
Junio C Hamano75485c82007-05-19 04:20:332118Linus by default.
2119
2120-------------------------------------------------
2121$ git branch --track test origin/master
2122$ git branch --track release origin/master
2123-------------------------------------------------
2124
Junio C Hamano35738e82008-01-07 07:55:462125These can be easily kept up to date using linkgit:git-pull[1].
Junio C Hamano75485c82007-05-19 04:20:332126
2127-------------------------------------------------
2128$ git checkout test && git pull
2129$ git checkout release && git pull
2130-------------------------------------------------
2131
2132Important note! If you have any local changes in these branches, then
2133this merge will create a commit object in the history (with no local
Junio C Hamano3f680f32009-11-16 02:10:542134changes git will simply do a "fast-forward" merge). Many people dislike
Junio C Hamano75485c82007-05-19 04:20:332135the "noise" that this creates in the Linux history, so you should avoid
2136doing this capriciously in the "release" branch, as these noisy commits
2137will become part of the permanent history when you ask Linus to pull
2138from the release branch.
2139
Junio C Hamano35738e82008-01-07 07:55:462140A few configuration variables (see linkgit:git-config[1]) can
Junio C Hamano75485c82007-05-19 04:20:332141make it easy to push both branches to your public tree. (See
2142<<setting-up-a-public-repository>>.)
2143
2144-------------------------------------------------
2145$ cat >> .git/config <<EOF
2146[remote "mytree"]
2147url = master.kernel.org:/pub/scm/linux/kernel/git/aegl/linux-2.6.git
2148push = release
2149push = test
2150EOF
2151-------------------------------------------------
2152
2153Then you can push both the test and release trees using
Junio C Hamano35738e82008-01-07 07:55:462154linkgit:git-push[1]:
Junio C Hamano75485c82007-05-19 04:20:332155
2156-------------------------------------------------
2157$ git push mytree
2158-------------------------------------------------
2159
2160or push just one of the test and release branches using:
2161
2162-------------------------------------------------
2163$ git push mytree test
2164-------------------------------------------------
2165
2166or
2167
2168-------------------------------------------------
2169$ git push mytree release
2170-------------------------------------------------
2171
2172Now to apply some patches from the community. Think of a short
2173snappy name for a branch to hold this patch (or related group of
Junio C Hamanoc27b7332010-10-14 04:37:282174patches), and create a new branch from a recent stable tag of
2175Linus's branch. Picking a stable base for your branch will:
21761) help you: by avoiding inclusion of unrelated and perhaps lightly
2177tested changes
21782) help future bug hunters that use "git bisect" to find problems
Junio C Hamano75485c82007-05-19 04:20:332179
2180-------------------------------------------------
Junio C Hamanoc27b7332010-10-14 04:37:282181$ git checkout -b speed-up-spinlocks v2.6.35
Junio C Hamano75485c82007-05-19 04:20:332182-------------------------------------------------
2183
2184Now you apply the patch(es), run some tests, and commit the change(s). If
2185the patch is a multi-part series, then you should apply each as a separate
2186commit to this branch.
2187
2188-------------------------------------------------
2189$ ... patch ... test ... commit [ ... patch ... test ... commit ]*
2190-------------------------------------------------
2191
2192When you are happy with the state of this change, you can pull it into the
2193"test" branch in preparation to make it public:
2194
2195-------------------------------------------------
2196$ git checkout test && git pull . speed-up-spinlocks
2197-------------------------------------------------
2198
2199It is unlikely that you would have any conflicts here ... but you might if you
2200spent a while on this step and had also pulled new versions from upstream.
2201
2202Some time later when enough time has passed and testing done, you can pull the
2203same branch into the "release" tree ready to go upstream. This is where you
2204see the value of keeping each patch (or patch series) in its own branch. It
2205means that the patches can be moved into the "release" tree in any order.
2206
2207-------------------------------------------------
2208$ git checkout release && git pull . speed-up-spinlocks
2209-------------------------------------------------
2210
2211After a while, you will have a number of branches, and despite the
2212well chosen names you picked for each of them, you may forget what
2213they are for, or what status they are in. To get a reminder of what
2214changes are in a specific branch, use:
2215
2216-------------------------------------------------
Junio C Hamanoba4b9282008-07-06 05:20:312217$ git log linux..branchname | git shortlog
Junio C Hamano75485c82007-05-19 04:20:332218-------------------------------------------------
2219
Junio C Hamano764a6672007-10-23 01:23:312220To see whether it has already been merged into the test or release branches,
Junio C Hamano75485c82007-05-19 04:20:332221use:
2222
2223-------------------------------------------------
2224$ git log test..branchname
2225-------------------------------------------------
2226
2227or
2228
2229-------------------------------------------------
2230$ git log release..branchname
2231-------------------------------------------------
2232
Junio C Hamano764a6672007-10-23 01:23:312233(If this branch has not yet been merged, you will see some log entries.
Junio C Hamano75485c82007-05-19 04:20:332234If it has been merged, then there will be no output.)
2235
2236Once a patch completes the great cycle (moving from test to release,
2237then pulled by Linus, and finally coming back into your local
Junio C Hamano764a6672007-10-23 01:23:312238"origin/master" branch), the branch for this change is no longer needed.
Junio C Hamano75485c82007-05-19 04:20:332239You detect this when the output from:
2240
2241-------------------------------------------------
2242$ git log origin..branchname
2243-------------------------------------------------
2244
2245is empty. At this point the branch can be deleted:
2246
2247-------------------------------------------------
2248$ git branch -d branchname
2249-------------------------------------------------
2250
2251Some changes are so trivial that it is not necessary to create a separate
2252branch and then merge into each of the test and release branches. For
2253these changes, just apply directly to the "release" branch, and then
2254merge that into the "test" branch.
2255
2256To create diffstat and shortlog summaries of changes to include in a "please
2257pull" request to Linus you can use:
2258
2259-------------------------------------------------
2260$ git diff --stat origin..release
2261-------------------------------------------------
2262
2263and
2264
2265-------------------------------------------------
2266$ git log -p origin..release | git shortlog
2267-------------------------------------------------
2268
2269Here are some of the scripts that simplify all this even further.
2270
2271-------------------------------------------------
2272==== update script ====
2273# Update a branch in my GIT tree. If the branch to be updated
2274# is origin, then pull from kernel.org. Otherwise merge
2275# origin/master branch into test|release branch
2276
2277case "$1" in
2278test|release)
2279git checkout $1 && git pull . origin
2280;;
2281origin)
Junio C Hamano9810d632007-09-24 01:05:342282before=$(git rev-parse refs/remotes/origin/master)
Junio C Hamano75485c82007-05-19 04:20:332283git fetch origin
Junio C Hamano9810d632007-09-24 01:05:342284after=$(git rev-parse refs/remotes/origin/master)
Junio C Hamano75485c82007-05-19 04:20:332285if [ $before != $after ]
2286then
2287git log $before..$after | git shortlog
2288fi
2289;;
2290*)
2291echo "Usage: $0 origin|test|release" 1>&2
2292exit 1
2293;;
2294esac
2295-------------------------------------------------
2296
2297-------------------------------------------------
2298==== merge script ====
2299# Merge a branch into either the test or release branch
2300
2301pname=$0
2302
2303usage()
2304{
2305echo "Usage: $pname branch test|release" 1>&2
2306exit 1
2307}
2308
Junio C Hamano9810d632007-09-24 01:05:342309git show-ref -q --verify -- refs/heads/"$1" || {
Junio C Hamano75485c82007-05-19 04:20:332310echo "Can't see branch <$1>" 1>&2
2311usage
Junio C Hamano9810d632007-09-24 01:05:342312}
Junio C Hamano75485c82007-05-19 04:20:332313
2314case "$2" in
2315test|release)
2316if [ $(git log $2..$1 | wc -c) -eq 0 ]
2317then
2318echo $1 already merged into $2 1>&2
2319exit 1
2320fi
2321git checkout $2 && git pull . $1
2322;;
2323*)
2324usage
2325;;
2326esac
2327-------------------------------------------------
2328
2329-------------------------------------------------
2330==== status script ====
2331# report on status of my ia64 GIT tree
2332
2333gb=$(tput setab 2)
2334rb=$(tput setab 1)
2335restore=$(tput setab 9)
2336
2337if [ `git rev-list test..release | wc -c` -gt 0 ]
2338then
2339echo $rb Warning: commits in release that are not in test $restore
2340git log test..release
2341fi
2342
Junio C Hamano9810d632007-09-24 01:05:342343for branch in `git show-ref --heads | sed 's|^.*/||'`
Junio C Hamano75485c82007-05-19 04:20:332344do
2345if [ $branch = test -o $branch = release ]
2346then
2347continue
2348fi
2349
2350echo -n $gb ======= $branch ====== $restore " "
2351status=
2352for ref in test release origin/master
2353do
2354if [ `git rev-list $ref..$branch | wc -c` -gt 0 ]
2355then
2356status=$status${ref:0:1}
2357fi
2358done
2359case $status in
2360trl)
2361echo $rb Need to pull into test $restore
2362;;
2363rl)
2364echo "In test"
2365;;
2366l)
2367echo "Waiting for linus"
2368;;
2369"")
2370echo $rb All done $restore
2371;;
2372*)
2373echo $rb "<$status>" $restore
2374;;
2375esac
2376git log origin/master..$branch | git shortlog
2377done
2378-------------------------------------------------
Junio C Hamano8f62db92007-02-01 00:22:222379
2380
2381[[cleaning-up-history]]
2382Rewriting history and maintaining patch series
2383==============================================
2384
2385Normally commits are only added to a project, never taken away or
2386replaced. Git is designed with this assumption, and violating it will
2387cause git's merge machinery (for example) to do the wrong thing.
2388
2389However, there is a situation in which it can be useful to violate this
2390assumption.
2391
Junio C Hamano3d30fd52007-05-08 00:32:532392[[patch-series]]
Junio C Hamano8f62db92007-02-01 00:22:222393Creating the perfect patch series
2394---------------------------------
2395
2396Suppose you are a contributor to a large project, and you want to add a
2397complicated feature, and to present it to the other developers in a way
2398that makes it easy for them to read your changes, verify that they are
2399correct, and understand why you made each change.
2400
2401If you present all of your changes as a single patch (or commit), they
Junio C Hamanodb911ee2007-02-28 08:13:522402may find that it is too much to digest all at once.
Junio C Hamano8f62db92007-02-01 00:22:222403
2404If you present them with the entire history of your work, complete with
2405mistakes, corrections, and dead ends, they may be overwhelmed.
2406
2407So the ideal is usually to produce a series of patches such that:
2408
24091. Each patch can be applied in order.
2410
24112. Each patch includes a single logical change, together with a
2412 message explaining the change.
2413
24143. No patch introduces a regression: after applying any initial
2415 part of the series, the resulting project still compiles and
2416 works, and has no bugs that it didn't have before.
2417
24184. The complete series produces the same end result as your own
2419 (probably much messier!) development process did.
2420
2421We will introduce some tools that can help you do this, explain how to
2422use them, and then explain some of the problems that can arise because
2423you are rewriting history.
2424
Junio C Hamano3d30fd52007-05-08 00:32:532425[[using-git-rebase]]
Junio C Hamano5f9a6f02009-04-06 08:26:562426Keeping a patch series up to date using git rebase
Junio C Hamano8f62db92007-02-01 00:22:222427--------------------------------------------------
2428
Junio C Hamanodb911ee2007-02-28 08:13:522429Suppose that you create a branch "mywork" on a remote-tracking branch
2430"origin", and create some commits on top of it:
Junio C Hamano8f62db92007-02-01 00:22:222431
2432-------------------------------------------------
2433$ git checkout -b mywork origin
2434$ vi file.txt
2435$ git commit
2436$ vi otherfile.txt
2437$ git commit
2438...
2439-------------------------------------------------
2440
2441You have performed no merges into mywork, so it is just a simple linear
2442sequence of patches on top of "origin":
2443
Junio C Hamanoc51fede2007-03-12 07:29:202444................................................
Junio C Hamano3b4609d2010-09-30 00:04:342445 o--o--O <-- origin
Junio C Hamano8f62db92007-02-01 00:22:222446 \
Junio C Hamano3b4609d2010-09-30 00:04:342447 a--b--c <-- mywork
Junio C Hamanoc51fede2007-03-12 07:29:202448................................................
Junio C Hamano8f62db92007-02-01 00:22:222449
2450Some more interesting work has been done in the upstream project, and
2451"origin" has advanced:
2452
Junio C Hamanoc51fede2007-03-12 07:29:202453................................................
Junio C Hamano8f62db92007-02-01 00:22:222454 o--o--O--o--o--o <-- origin
2455 \
2456 a--b--c <-- mywork
Junio C Hamanoc51fede2007-03-12 07:29:202457................................................
Junio C Hamano8f62db92007-02-01 00:22:222458
2459At this point, you could use "pull" to merge your changes back in;
2460the result would create a new merge commit, like this:
2461
Junio C Hamanoc51fede2007-03-12 07:29:202462................................................
Junio C Hamano8f62db92007-02-01 00:22:222463 o--o--O--o--o--o <-- origin
2464 \ \
2465 a--b--c--m <-- mywork
Junio C Hamanoc51fede2007-03-12 07:29:202466................................................
Junio C Hamanoa77a5132007-06-08 16:13:442467
Junio C Hamano8f62db92007-02-01 00:22:222468However, if you prefer to keep the history in mywork a simple series of
2469commits without any merges, you may instead choose to use
Junio C Hamano35738e82008-01-07 07:55:462470linkgit:git-rebase[1]:
Junio C Hamano8f62db92007-02-01 00:22:222471
2472-------------------------------------------------
2473$ git checkout mywork
2474$ git rebase origin
2475-------------------------------------------------
2476
2477This will remove each of your commits from mywork, temporarily saving
Junio C Hamano0868a302008-07-22 09:20:442478them as patches (in a directory named ".git/rebase-apply"), update mywork to
Junio C Hamano8f62db92007-02-01 00:22:222479point at the latest version of origin, then apply each of the saved
2480patches to the new mywork. The result will look like:
2481
2482
Junio C Hamanoc51fede2007-03-12 07:29:202483................................................
Junio C Hamano8f62db92007-02-01 00:22:222484 o--o--O--o--o--o <-- origin
2485 \
2486 a'--b'--c' <-- mywork
Junio C Hamanoc51fede2007-03-12 07:29:202487................................................
Junio C Hamano8f62db92007-02-01 00:22:222488
2489In the process, it may discover conflicts. In that case it will stop
Junio C Hamano5f9a6f02009-04-06 08:26:562490and allow you to fix the conflicts; after fixing conflicts, use `git add`
Junio C Hamanoba4b9282008-07-06 05:20:312491to update the index with those contents, and then, instead of
Junio C Hamano5f9a6f02009-04-06 08:26:562492running `git commit`, just run
Junio C Hamano8f62db92007-02-01 00:22:222493
2494-------------------------------------------------
2495$ git rebase --continue
2496-------------------------------------------------
2497
2498and git will continue applying the rest of the patches.
2499
Junio C Hamano764a6672007-10-23 01:23:312500At any point you may use the `--abort` option to abort this process and
Junio C Hamano8f62db92007-02-01 00:22:222501return mywork to the state it had before you started the rebase:
2502
2503-------------------------------------------------
2504$ git rebase --abort
2505-------------------------------------------------
2506
Junio C Hamanoce3650e2007-11-26 04:20:112507[[rewriting-one-commit]]
2508Rewriting a single commit
Junio C Hamanoaa83a7d2007-03-05 02:37:292509-------------------------
2510
Junio C Hamanoce3650e2007-11-26 04:20:112511We saw in <<fixing-a-mistake-by-rewriting-history>> that you can replace the
Junio C Hamanoaa83a7d2007-03-05 02:37:292512most recent commit using
2513
2514-------------------------------------------------
2515$ git commit --amend
2516-------------------------------------------------
2517
2518which will replace the old commit by a new commit incorporating your
2519changes, giving you a chance to edit the old commit message first.
2520
Junio C Hamano35738e82008-01-07 07:55:462521You can also use a combination of this and linkgit:git-rebase[1] to
Junio C Hamanoce3650e2007-11-26 04:20:112522replace a commit further back in your history and recreate the
2523intervening changes on top of it. First, tag the problematic commit
2524with
Junio C Hamanoaa83a7d2007-03-05 02:37:292525
2526-------------------------------------------------
2527$ git tag bad mywork~5
2528-------------------------------------------------
2529
Junio C Hamano5f9a6f02009-04-06 08:26:562530(Either gitk or `git log` may be useful for finding the commit.)
Junio C Hamanoaa83a7d2007-03-05 02:37:292531
Junio C Hamano0e3cb532007-04-17 08:28:112532Then check out that commit, edit it, and rebase the rest of the series
2533on top of it (note that we could check out the commit on a temporary
2534branch, but instead we're using a <<detached-head,detached head>>):
Junio C Hamanoaa83a7d2007-03-05 02:37:292535
2536-------------------------------------------------
Junio C Hamano0e3cb532007-04-17 08:28:112537$ git checkout bad
Junio C Hamanoaa83a7d2007-03-05 02:37:292538$ # make changes here and update the index
2539$ git commit --amend
Junio C Hamano0e3cb532007-04-17 08:28:112540$ git rebase --onto HEAD bad mywork
Junio C Hamanoaa83a7d2007-03-05 02:37:292541-------------------------------------------------
2542
Junio C Hamano0e3cb532007-04-17 08:28:112543When you're done, you'll be left with mywork checked out, with the top
2544patches on mywork reapplied on top of your modified commit. You can
Junio C Hamanoaa83a7d2007-03-05 02:37:292545then clean up with
2546
2547-------------------------------------------------
Junio C Hamanoaa83a7d2007-03-05 02:37:292548$ git tag -d bad
2549-------------------------------------------------
2550
2551Note that the immutable nature of git history means that you haven't really
2552"modified" existing commits; instead, you have replaced the old commits with
2553new commits having new object names.
2554
Junio C Hamano3d30fd52007-05-08 00:32:532555[[reordering-patch-series]]
Junio C Hamano8f62db92007-02-01 00:22:222556Reordering or selecting from a patch series
2557-------------------------------------------
2558
Junio C Hamano35738e82008-01-07 07:55:462559Given one existing commit, the linkgit:git-cherry-pick[1] command
Junio C Hamano8f62db92007-02-01 00:22:222560allows you to apply the change introduced by that commit and create a
2561new commit that records it. So, for example, if "mywork" points to a
2562series of patches on top of "origin", you might do something like:
2563
2564-------------------------------------------------
2565$ git checkout -b mywork-new origin
2566$ gitk origin..mywork &
2567-------------------------------------------------
2568
Junio C Hamano764a6672007-10-23 01:23:312569and browse through the list of patches in the mywork branch using gitk,
Junio C Hamano8f62db92007-02-01 00:22:222570applying them (possibly in a different order) to mywork-new using
Junio C Hamano5f9a6f02009-04-06 08:26:562571cherry-pick, and possibly modifying them as you go using `git commit --amend`.
Junio C Hamano35738e82008-01-07 07:55:462572The linkgit:git-gui[1] command may also help as it allows you to
Junio C Hamano8b8b0f22007-08-26 22:10:262573individually select diff hunks for inclusion in the index (by
2574right-clicking on the diff hunk and choosing "Stage Hunk for Commit").
Junio C Hamano8f62db92007-02-01 00:22:222575
Junio C Hamano5f9a6f02009-04-06 08:26:562576Another technique is to use `git format-patch` to create a series of
Junio C Hamano8f62db92007-02-01 00:22:222577patches, then reset the state to before the patches:
2578
2579-------------------------------------------------
2580$ git format-patch origin
2581$ git reset --hard origin
2582-------------------------------------------------
2583
2584Then modify, reorder, or eliminate patches as preferred before applying
Junio C Hamano35738e82008-01-07 07:55:462585them again with linkgit:git-am[1].
Junio C Hamano8f62db92007-02-01 00:22:222586
Junio C Hamano3d30fd52007-05-08 00:32:532587[[patch-series-tools]]
Junio C Hamano8f62db92007-02-01 00:22:222588Other tools
2589-----------
2590
Junio C Hamanobf984de2009-11-23 06:11:192591There are numerous other tools, such as StGit, which exist for the
Junio C Hamanodb911ee2007-02-28 08:13:522592purpose of maintaining a patch series. These are outside of the scope of
Junio C Hamano8f62db92007-02-01 00:22:222593this manual.
2594
Junio C Hamanoec87f522008-12-10 08:35:252595[[problems-With-rewriting-history]]
Junio C Hamano8f62db92007-02-01 00:22:222596Problems with rewriting history
2597-------------------------------
2598
2599The primary problem with rewriting the history of a branch has to do
2600with merging. Suppose somebody fetches your branch and merges it into
2601their branch, with a result something like this:
2602
Junio C Hamanoc51fede2007-03-12 07:29:202603................................................
Junio C Hamano8f62db92007-02-01 00:22:222604 o--o--O--o--o--o <-- origin
2605 \ \
2606 t--t--t--m <-- their branch:
Junio C Hamanoc51fede2007-03-12 07:29:202607................................................
Junio C Hamano8f62db92007-02-01 00:22:222608
2609Then suppose you modify the last three commits:
2610
Junio C Hamanoc51fede2007-03-12 07:29:202611................................................
Junio C Hamano8f62db92007-02-01 00:22:222612 o--o--o <-- new head of origin
2613/
2614 o--o--O--o--o--o <-- old head of origin
Junio C Hamanoc51fede2007-03-12 07:29:202615................................................
Junio C Hamano8f62db92007-02-01 00:22:222616
2617If we examined all this history together in one repository, it will
2618look like:
2619
Junio C Hamanoc51fede2007-03-12 07:29:202620................................................
Junio C Hamano8f62db92007-02-01 00:22:222621 o--o--o <-- new head of origin
2622/
2623 o--o--O--o--o--o <-- old head of origin
2624 \ \
2625 t--t--t--m <-- their branch:
Junio C Hamanoc51fede2007-03-12 07:29:202626................................................
Junio C Hamano8f62db92007-02-01 00:22:222627
2628Git has no way of knowing that the new head is an updated version of
2629the old head; it treats this situation exactly the same as it would if
2630two developers had independently done the work on the old and new heads
2631in parallel. At this point, if someone attempts to merge the new head
2632in to their branch, git will attempt to merge together the two (old and
2633new) lines of development, instead of trying to replace the old by the
2634new. The results are likely to be unexpected.
2635
2636You may still choose to publish branches whose history is rewritten,
2637and it may be useful for others to be able to fetch those branches in
2638order to examine or test them, but they should not attempt to pull such
2639branches into their own work.
2640
2641For true distributed development that supports proper merging,
2642published branches should never be rewritten.
2643
Junio C Hamano393e57f2007-11-20 04:53:252644[[bisect-merges]]
2645Why bisecting merge commits can be harder than bisecting linear history
2646-----------------------------------------------------------------------
2647
Junio C Hamano35738e82008-01-07 07:55:462648The linkgit:git-bisect[1] command correctly handles history that
Junio C Hamano393e57f2007-11-20 04:53:252649includes merge commits. However, when the commit that it finds is a
2650merge commit, the user may need to work harder than usual to figure out
2651why that commit introduced a problem.
2652
2653Imagine this history:
2654
2655................................................
2656 ---Z---o---X---...---o---A---C---D
2657 \ /
2658 o---o---Y---...---o---B
2659................................................
2660
2661Suppose that on the upper line of development, the meaning of one
2662of the functions that exists at Z is changed at commit X. The
2663commits from Z leading to A change both the function's
2664implementation and all calling sites that exist at Z, as well
2665as new calling sites they add, to be consistent. There is no
2666bug at A.
2667
2668Suppose that in the meantime on the lower line of development somebody
2669adds a new calling site for that function at commit Y. The
2670commits from Z leading to B all assume the old semantics of that
2671function and the callers and the callee are consistent with each
2672other. There is no bug at B, either.
2673
2674Suppose further that the two development lines merge cleanly at C,
2675so no conflict resolution is required.
2676
2677Nevertheless, the code at C is broken, because the callers added
2678on the lower line of development have not been converted to the new
2679semantics introduced on the upper line of development. So if all
2680you know is that D is bad, that Z is good, and that
Junio C Hamano35738e82008-01-07 07:55:462681linkgit:git-bisect[1] identifies C as the culprit, how will you
Junio C Hamano393e57f2007-11-20 04:53:252682figure out that the problem is due to this change in semantics?
2683
Junio C Hamano5f9a6f02009-04-06 08:26:562684When the result of a `git bisect` is a non-merge commit, you should
Junio C Hamano393e57f2007-11-20 04:53:252685normally be able to discover the problem by examining just that commit.
2686Developers can make this easy by breaking their changes into small
2687self-contained commits. That won't help in the case above, however,
2688because the problem isn't obvious from examination of any single
2689commit; instead, a global view of the development is required. To
2690make matters worse, the change in semantics in the problematic
2691function may be just one small part of the changes in the upper
2692line of development.
2693
2694On the other hand, if instead of merging at C you had rebased the
2695history between Z to B on top of A, you would have gotten this
2696linear history:
2697
2698................................................................
2699 ---Z---o---X--...---o---A---o---o---Y*--...---o---B*--D*
2700................................................................
2701
2702Bisecting between Z and D* would hit a single culprit commit Y*,
2703and understanding why Y* was broken would probably be easier.
2704
2705Partly for this reason, many experienced git users, even when
2706working on an otherwise merge-heavy project, keep the history
2707linear by rebasing against the latest upstream version before
2708publishing.
2709
Junio C Hamano3d30fd52007-05-08 00:32:532710[[advanced-branch-management]]
Junio C Hamano8f62db92007-02-01 00:22:222711Advanced branch management
2712==========================
2713
Junio C Hamano3d30fd52007-05-08 00:32:532714[[fetching-individual-branches]]
Junio C Hamano8f62db92007-02-01 00:22:222715Fetching individual branches
2716----------------------------
2717
Junio C Hamano35738e82008-01-07 07:55:462718Instead of using linkgit:git-remote[1], you can also choose just
Junio C Hamano8f62db92007-02-01 00:22:222719to update one branch at a time, and to store it locally under an
2720arbitrary name:
2721
2722-------------------------------------------------
2723$ git fetch origin todo:my-todo-work
2724-------------------------------------------------
2725
2726The first argument, "origin", just tells git to fetch from the
2727repository you originally cloned from. The second argument tells git
2728to fetch the branch named "todo" from the remote repository, and to
2729store it locally under the name refs/heads/my-todo-work.
2730
2731You can also fetch branches from other repositories; so
2732
2733-------------------------------------------------
2734$ git fetch git://example.com/proj.git master:example-master
2735-------------------------------------------------
2736
2737will create a new branch named "example-master" and store in it the
2738branch named "master" from the repository at the given URL. If you
2739already have a branch named example-master, it will attempt to
Junio C Hamano3d30fd52007-05-08 00:32:532740<<fast-forwards,fast-forward>> to the commit given by example.com's
2741master branch. In more detail:
Junio C Hamano8f62db92007-02-01 00:22:222742
Junio C Hamano3d30fd52007-05-08 00:32:532743[[fetch-fast-forwards]]
2744git fetch and fast-forwards
2745---------------------------
Junio C Hamano8f62db92007-02-01 00:22:222746
Junio C Hamano5f9a6f02009-04-06 08:26:562747In the previous example, when updating an existing branch, "git fetch"
Junio C Hamanoba4b9282008-07-06 05:20:312748checks to make sure that the most recent commit on the remote
Junio C Hamano8f62db92007-02-01 00:22:222749branch is a descendant of the most recent commit on your copy of the
2750branch before updating your copy of the branch to point at the new
Junio C Hamano3f680f32009-11-16 02:10:542751commit. Git calls this process a <<fast-forwards,fast-forward>>.
Junio C Hamano8f62db92007-02-01 00:22:222752
Junio C Hamano3f680f32009-11-16 02:10:542753A fast-forward looks something like this:
Junio C Hamano8f62db92007-02-01 00:22:222754
Junio C Hamanoc51fede2007-03-12 07:29:202755................................................
Junio C Hamano8f62db92007-02-01 00:22:222756 o--o--o--o <-- old head of the branch
2757 \
2758 o--o--o <-- new head of the branch
Junio C Hamanoc51fede2007-03-12 07:29:202759................................................
Junio C Hamano8f62db92007-02-01 00:22:222760
2761
2762In some cases it is possible that the new head will *not* actually be
2763a descendant of the old head. For example, the developer may have
2764realized she made a serious mistake, and decided to backtrack,
2765resulting in a situation like:
2766
Junio C Hamanoc51fede2007-03-12 07:29:202767................................................
Junio C Hamano8f62db92007-02-01 00:22:222768 o--o--o--o--a--b <-- old head of the branch
2769 \
2770 o--o--o <-- new head of the branch
Junio C Hamanoc51fede2007-03-12 07:29:202771................................................
Junio C Hamano8f62db92007-02-01 00:22:222772
Junio C Hamano5f9a6f02009-04-06 08:26:562773In this case, "git fetch" will fail, and print out a warning.
Junio C Hamano8f62db92007-02-01 00:22:222774
2775In that case, you can still force git to update to the new head, as
2776described in the following section. However, note that in the
2777situation above this may mean losing the commits labeled "a" and "b",
2778unless you've already created a reference of your own pointing to
2779them.
2780
Junio C Hamano3d30fd52007-05-08 00:32:532781[[forcing-fetch]]
Junio C Hamano5f9a6f02009-04-06 08:26:562782Forcing git fetch to do non-fast-forward updates
Junio C Hamano8f62db92007-02-01 00:22:222783------------------------------------------------
2784
2785If git fetch fails because the new head of a branch is not a
2786descendant of the old head, you may force the update with:
2787
2788-------------------------------------------------
2789$ git fetch git://example.com/proj.git +master:refs/remotes/example/master
2790-------------------------------------------------
2791
Junio C Hamano3d30fd52007-05-08 00:32:532792Note the addition of the "+" sign. Alternatively, you can use the "-f"
2793flag to force updates of all the fetched branches, as in:
Junio C Hamano8f62db92007-02-01 00:22:222794
Junio C Hamano3d30fd52007-05-08 00:32:532795-------------------------------------------------
2796$ git fetch -f origin
2797-------------------------------------------------
2798
2799Be aware that commits that the old version of example/master pointed at
2800may be lost, as we saw in the previous section.
2801
2802[[remote-branch-configuration]]
Junio C Hamano8f62db92007-02-01 00:22:222803Configuring remote branches
2804---------------------------
2805
2806We saw above that "origin" is just a shortcut to refer to the
Junio C Hamanodb911ee2007-02-28 08:13:522807repository that you originally cloned from. This information is
Junio C Hamano8f62db92007-02-01 00:22:222808stored in git configuration variables, which you can see using
Junio C Hamano35738e82008-01-07 07:55:462809linkgit:git-config[1]:
Junio C Hamano8f62db92007-02-01 00:22:222810
2811-------------------------------------------------
2812$ git config -l
2813core.repositoryformatversion=0
2814core.filemode=true
2815core.logallrefupdates=true
2816remote.origin.url=git://git.kernel.org/pub/scm/git/git.git
2817remote.origin.fetch=+refs/heads/*:refs/remotes/origin/*
2818branch.master.remote=origin
2819branch.master.merge=refs/heads/master
2820-------------------------------------------------
2821
2822If there are other repositories that you also use frequently, you can
2823create similar configuration options to save typing; for example,
2824after
2825
2826-------------------------------------------------
2827$ git config remote.example.url git://example.com/proj.git
2828-------------------------------------------------
2829
2830then the following two commands will do the same thing:
2831
2832-------------------------------------------------
2833$ git fetch git://example.com/proj.git master:refs/remotes/example/master
2834$ git fetch example master:refs/remotes/example/master
2835-------------------------------------------------
2836
2837Even better, if you add one more option:
2838
2839-------------------------------------------------
2840$ git config remote.example.fetch master:refs/remotes/example/master
2841-------------------------------------------------
2842
2843then the following commands will all do the same thing:
2844
2845-------------------------------------------------
Junio C Hamano91d44c52007-05-09 07:16:072846$ git fetch git://example.com/proj.git master:refs/remotes/example/master
2847$ git fetch example master:refs/remotes/example/master
Junio C Hamano8f62db92007-02-01 00:22:222848$ git fetch example
2849-------------------------------------------------
2850
2851You can also add a "+" to force the update each time:
2852
2853-------------------------------------------------
2854$ git config remote.example.fetch +master:ref/remotes/example/master
2855-------------------------------------------------
2856
Junio C Hamano1d368882008-08-11 22:03:102857Don't do this unless you're sure you won't mind "git fetch" possibly
2858throwing away commits on 'example/master'.
Junio C Hamano8f62db92007-02-01 00:22:222859
2860Also note that all of the above configuration can be performed by
2861directly editing the file .git/config instead of using
Junio C Hamano35738e82008-01-07 07:55:462862linkgit:git-config[1].
Junio C Hamano8f62db92007-02-01 00:22:222863
Junio C Hamano35738e82008-01-07 07:55:462864See linkgit:git-config[1] for more details on the configuration
Junio C Hamano8f62db92007-02-01 00:22:222865options mentioned above.
2866
2867
Junio C Hamano597ffcf2007-09-17 17:33:152868[[git-concepts]]
2869Git concepts
2870============
Junio C Hamano8f62db92007-02-01 00:22:222871
Junio C Hamano597ffcf2007-09-17 17:33:152872Git is built on a small number of simple but powerful ideas. While it
2873is possible to get things done without understanding them, you will find
2874git much more intuitive if you do.
2875
2876We start with the most important, the <<def_object_database,object
2877database>> and the <<def_index,index>>.
Junio C Hamano8f62db92007-02-01 00:22:222878
Junio C Hamano3d30fd52007-05-08 00:32:532879[[the-object-database]]
Junio C Hamano8f62db92007-02-01 00:22:222880The Object Database
2881-------------------
2882
Junio C Hamano8f62db92007-02-01 00:22:222883
Junio C Hamano597ffcf2007-09-17 17:33:152884We already saw in <<understanding-commits>> that all commits are stored
2885under a 40-digit "object name". In fact, all the information needed to
2886represent the history of a project is stored in objects with such names.
Junio C Hamano5f9a6f02009-04-06 08:26:562887In each case the name is calculated by taking the SHA-1 hash of the
2888contents of the object. The SHA-1 hash is a cryptographic hash function.
Junio C Hamano597ffcf2007-09-17 17:33:152889What that means to us is that it is impossible to find two different
2890objects with the same name. This has a number of advantages; among
2891others:
Junio C Hamano8f62db92007-02-01 00:22:222892
Junio C Hamano597ffcf2007-09-17 17:33:152893- Git can quickly determine whether two objects are identical or not,
2894 just by comparing names.
Junio C Hamano764a6672007-10-23 01:23:312895- Since object names are computed the same way in every repository, the
Junio C Hamano597ffcf2007-09-17 17:33:152896 same content stored in two repositories will always be stored under
2897 the same name.
2898- Git can detect errors when it reads an object, by checking that the
Junio C Hamano5f9a6f02009-04-06 08:26:562899 object's name is still the SHA-1 hash of its contents.
Junio C Hamano8f62db92007-02-01 00:22:222900
Junio C Hamano597ffcf2007-09-17 17:33:152901(See <<object-details>> for the details of the object formatting and
Junio C Hamano5f9a6f02009-04-06 08:26:562902SHA-1 calculation.)
Junio C Hamano8f62db92007-02-01 00:22:222903
Junio C Hamano597ffcf2007-09-17 17:33:152904There are four different types of objects: "blob", "tree", "commit", and
2905"tag".
Junio C Hamano8f62db92007-02-01 00:22:222906
Junio C Hamano597ffcf2007-09-17 17:33:152907- A <<def_blob_object,"blob" object>> is used to store file data.
Junio C Hamanod32738e2008-07-09 19:53:422908- A <<def_tree_object,"tree" object>> ties one or more
Junio C Hamano597ffcf2007-09-17 17:33:152909 "blob" objects into a directory structure. In addition, a tree object
2910 can refer to other tree objects, thus creating a directory hierarchy.
2911- A <<def_commit_object,"commit" object>> ties such directory hierarchies
Junio C Hamano764a6672007-10-23 01:23:312912 together into a <<def_DAG,directed acyclic graph>> of revisions--each
Junio C Hamano597ffcf2007-09-17 17:33:152913 commit contains the object name of exactly one tree designating the
2914 directory hierarchy at the time of the commit. In addition, a commit
2915 refers to "parent" commit objects that describe the history of how we
2916 arrived at that directory hierarchy.
2917- A <<def_tag_object,"tag" object>> symbolically identifies and can be
2918 used to sign other objects. It contains the object name and type of
2919 another object, a symbolic name (of course!) and, optionally, a
2920 signature.
Junio C Hamano8f62db92007-02-01 00:22:222921
2922The object types in some more detail:
2923
Junio C Hamano597ffcf2007-09-17 17:33:152924[[commit-object]]
2925Commit Object
2926~~~~~~~~~~~~~
Junio C Hamano8f62db92007-02-01 00:22:222927
Junio C Hamano597ffcf2007-09-17 17:33:152928The "commit" object links a physical state of a tree with a description
2929of how we got there and why. Use the --pretty=raw option to
Junio C Hamano35738e82008-01-07 07:55:462930linkgit:git-show[1] or linkgit:git-log[1] to examine your favorite
Junio C Hamano597ffcf2007-09-17 17:33:152931commit:
Junio C Hamano8f62db92007-02-01 00:22:222932
Junio C Hamano597ffcf2007-09-17 17:33:152933------------------------------------------------
2934$ git show -s --pretty=raw 2be7fcb476
2935commit 2be7fcb4764f2dbcee52635b91fedb1b3dcf7ab4
2936tree fb3a8bdd0ceddd019615af4d57a53f43d8cee2bf
2937parent 257a84d9d02e90447b149af58b271c19405edb6a
2938author Dave Watson <dwatson@mimvista.com> 1187576872 -0400
2939committer Junio C Hamano <gitster@pobox.com> 1187591163 -0700
Junio C Hamano8f62db92007-02-01 00:22:222940
Junio C Hamano597ffcf2007-09-17 17:33:152941 Fix misspelling of 'suppress' in docs
2942
2943 Signed-off-by: Junio C Hamano <gitster@pobox.com>
2944------------------------------------------------
2945
2946As you can see, a commit is defined by:
2947
Junio C Hamano5f9a6f02009-04-06 08:26:562948- a tree: The SHA-1 name of a tree object (as defined below), representing
Junio C Hamano597ffcf2007-09-17 17:33:152949 the contents of a directory at a certain point in time.
Junio C Hamano5f9a6f02009-04-06 08:26:562950- parent(s): The SHA-1 name of some number of commits which represent the
Junio C Hamano878cc1e2007-12-14 08:35:132951 immediately previous step(s) in the history of the project. The
Junio C Hamano597ffcf2007-09-17 17:33:152952 example above has one parent; merge commits may have more than
2953 one. A commit with no parents is called a "root" commit, and
2954 represents the initial revision of a project. Each project must have
2955 at least one root. A project can also have multiple roots, though
2956 that isn't common (or necessarily a good idea).
2957- an author: The name of the person responsible for this change, together
2958 with its date.
2959- a committer: The name of the person who actually created the commit,
2960 with the date it was done. This may be different from the author, for
2961 example, if the author was someone who wrote a patch and emailed it
2962 to the person who used it to create the commit.
2963- a comment describing this commit.
2964
2965Note that a commit does not itself contain any information about what
2966actually changed; all changes are calculated by comparing the contents
2967of the tree referred to by this commit with the trees associated with
2968its parents. In particular, git does not attempt to record file renames
2969explicitly, though it can identify cases where the existence of the same
2970file data at changing paths suggests a rename. (See, for example, the
Junio C Hamano35738e82008-01-07 07:55:462971-M option to linkgit:git-diff[1]).
Junio C Hamano597ffcf2007-09-17 17:33:152972
Junio C Hamano35738e82008-01-07 07:55:462973A commit is usually created by linkgit:git-commit[1], which creates a
Junio C Hamano597ffcf2007-09-17 17:33:152974commit whose parent is normally the current HEAD, and whose tree is
2975taken from the content currently stored in the index.
Junio C Hamano8f62db92007-02-01 00:22:222976
Junio C Hamano3d30fd52007-05-08 00:32:532977[[tree-object]]
Junio C Hamano8f62db92007-02-01 00:22:222978Tree Object
Junio C Hamano597ffcf2007-09-17 17:33:152979~~~~~~~~~~~
Junio C Hamano8f62db92007-02-01 00:22:222980
Junio C Hamano35738e82008-01-07 07:55:462981The ever-versatile linkgit:git-show[1] command can also be used to
2982examine tree objects, but linkgit:git-ls-tree[1] will give you more
Junio C Hamano597ffcf2007-09-17 17:33:152983details:
Junio C Hamano8f62db92007-02-01 00:22:222984
Junio C Hamano597ffcf2007-09-17 17:33:152985------------------------------------------------
2986$ git ls-tree fb3a8bdd0ce
2987100644 blob 63c918c667fa005ff12ad89437f2fdc80926e21c .gitignore
2988100644 blob 5529b198e8d14decbe4ad99db3f7fb632de0439d .mailmap
2989100644 blob 6ff87c4664981e4397625791c8ea3bbb5f2279a3 COPYING
2990040000 tree 2fb783e477100ce076f6bf57e4a6f026013dc745 Documentation
2991100755 blob 3c0032cec592a765692234f1cba47dfdcc3a9200 GIT-VERSION-GEN
2992100644 blob 289b046a443c0647624607d471289b2c7dcd470b INSTALL
2993100644 blob 4eb463797adc693dc168b926b6932ff53f17d0b1 Makefile
2994100644 blob 548142c327a6790ff8821d67c2ee1eff7a656b52 README
2995...
2996------------------------------------------------
Junio C Hamano8f62db92007-02-01 00:22:222997
Junio C Hamano597ffcf2007-09-17 17:33:152998As you can see, a tree object contains a list of entries, each with a
Junio C Hamano5f9a6f02009-04-06 08:26:562999mode, object type, SHA-1 name, and name, sorted by name. It represents
Junio C Hamano597ffcf2007-09-17 17:33:153000the contents of a single directory tree.
Junio C Hamano8f62db92007-02-01 00:22:223001
Junio C Hamano597ffcf2007-09-17 17:33:153002The object type may be a blob, representing the contents of a file, or
3003another tree, representing the contents of a subdirectory. Since trees
Junio C Hamano5f9a6f02009-04-06 08:26:563004and blobs, like all other objects, are named by the SHA-1 hash of their
3005contents, two trees have the same SHA-1 name if and only if their
Junio C Hamano597ffcf2007-09-17 17:33:153006contents (including, recursively, the contents of all subdirectories)
3007are identical. This allows git to quickly determine the differences
3008between two related tree objects, since it can ignore any entries with
3009identical object names.
Junio C Hamano8f62db92007-02-01 00:22:223010
Junio C Hamano597ffcf2007-09-17 17:33:153011(Note: in the presence of submodules, trees may also have commits as
Junio C Hamano4fd58d42007-09-30 00:51:143012entries. See <<submodules>> for documentation.)
Junio C Hamano8f62db92007-02-01 00:22:223013
Junio C Hamano597ffcf2007-09-17 17:33:153014Note that the files all have mode 644 or 755: git actually only pays
3015attention to the executable bit.
Junio C Hamano8f62db92007-02-01 00:22:223016
Junio C Hamano597ffcf2007-09-17 17:33:153017[[blob-object]]
3018Blob Object
3019~~~~~~~~~~~
Junio C Hamano8f62db92007-02-01 00:22:223020
Junio C Hamano35738e82008-01-07 07:55:463021You can use linkgit:git-show[1] to examine the contents of a blob; take,
Junio C Hamano597ffcf2007-09-17 17:33:153022for example, the blob in the entry for "COPYING" from the tree above:
Junio C Hamano8f62db92007-02-01 00:22:223023
Junio C Hamano597ffcf2007-09-17 17:33:153024------------------------------------------------
3025$ git show 6ff87c4664
Junio C Hamano8f62db92007-02-01 00:22:223026
Junio C Hamano597ffcf2007-09-17 17:33:153027 Note that the only valid version of the GPL as far as this project
3028 is concerned is _this_ particular version of the license (ie v2, not
3029 v2.2 or v3.x or whatever), unless explicitly otherwise stated.
3030...
3031------------------------------------------------
Junio C Hamano8f62db92007-02-01 00:22:223032
Junio C Hamano597ffcf2007-09-17 17:33:153033A "blob" object is nothing but a binary blob of data. It doesn't refer
3034to anything else or have attributes of any kind.
Junio C Hamano8f62db92007-02-01 00:22:223035
Junio C Hamano597ffcf2007-09-17 17:33:153036Since the blob is entirely defined by its data, if two files in a
3037directory tree (or in multiple different versions of the repository)
3038have the same contents, they will share the same blob object. The object
3039is totally independent of its location in the directory tree, and
3040renaming a file does not change the object that file is associated with.
3041
3042Note that any tree or blob object can be examined using
Junio C Hamano35738e82008-01-07 07:55:463043linkgit:git-show[1] with the <revision>:<path> syntax. This can
Junio C Hamano597ffcf2007-09-17 17:33:153044sometimes be useful for browsing the contents of a tree that is not
3045currently checked out.
Junio C Hamano8f62db92007-02-01 00:22:223046
Junio C Hamano3d30fd52007-05-08 00:32:533047[[trust]]
Junio C Hamano8f62db92007-02-01 00:22:223048Trust
Junio C Hamano597ffcf2007-09-17 17:33:153049~~~~~
Junio C Hamano8f62db92007-02-01 00:22:223050
Junio C Hamano5f9a6f02009-04-06 08:26:563051If you receive the SHA-1 name of a blob from one source, and its contents
Junio C Hamano597ffcf2007-09-17 17:33:153052from another (possibly untrusted) source, you can still trust that those
Junio C Hamano5f9a6f02009-04-06 08:26:563053contents are correct as long as the SHA-1 name agrees. This is because
3054the SHA-1 is designed so that it is infeasible to find different contents
Junio C Hamano597ffcf2007-09-17 17:33:153055that produce the same hash.
Junio C Hamano8f62db92007-02-01 00:22:223056
Junio C Hamano5f9a6f02009-04-06 08:26:563057Similarly, you need only trust the SHA-1 name of a top-level tree object
Junio C Hamano597ffcf2007-09-17 17:33:153058to trust the contents of the entire directory that it refers to, and if
Junio C Hamano5f9a6f02009-04-06 08:26:563059you receive the SHA-1 name of a commit from a trusted source, then you
Junio C Hamano597ffcf2007-09-17 17:33:153060can easily verify the entire history of commits reachable through
3061parents of that commit, and all of those contents of the trees referred
3062to by those commits.
Junio C Hamano8f62db92007-02-01 00:22:223063
3064So to introduce some real trust in the system, the only thing you need
3065to do is to digitally sign just 'one' special note, which includes the
3066name of a top-level commit. Your digital signature shows others
3067that you trust that commit, and the immutability of the history of
3068commits tells others that they can trust the whole history.
3069
3070In other words, you can easily validate a whole archive by just
Junio C Hamano5f9a6f02009-04-06 08:26:563071sending out a single email that tells the people the name (SHA-1 hash)
Junio C Hamano8f62db92007-02-01 00:22:223072of the top commit, and digitally sign that email using something
3073like GPG/PGP.
3074
3075To assist in this, git also provides the tag object...
3076
Junio C Hamano3d30fd52007-05-08 00:32:533077[[tag-object]]
Junio C Hamano8f62db92007-02-01 00:22:223078Tag Object
Junio C Hamano597ffcf2007-09-17 17:33:153079~~~~~~~~~~
Junio C Hamano8f62db92007-02-01 00:22:223080
Junio C Hamano597ffcf2007-09-17 17:33:153081A tag object contains an object, object type, tag name, the name of the
3082person ("tagger") who created the tag, and a message, which may contain
Junio C Hamanod32738e2008-07-09 19:53:423083a signature, as can be seen using linkgit:git-cat-file[1]:
Junio C Hamano8f62db92007-02-01 00:22:223084
Junio C Hamano597ffcf2007-09-17 17:33:153085------------------------------------------------
3086$ git cat-file tag v1.5.0
3087object 437b1b20df4b356c9342dac8d38849f24ef44f27
3088type commit
3089tag v1.5.0
3090tagger Junio C Hamano <junkio@cox.net> 1171411200 +0000
Junio C Hamano8f62db92007-02-01 00:22:223091
Junio C Hamano597ffcf2007-09-17 17:33:153092GIT 1.5.0
3093-----BEGIN PGP SIGNATURE-----
3094Version: GnuPG v1.4.6 (GNU/Linux)
Junio C Hamano8f62db92007-02-01 00:22:223095
Junio C Hamano597ffcf2007-09-17 17:33:153096iD8DBQBF0lGqwMbZpPMRm5oRAuRiAJ9ohBLd7s2kqjkKlq1qqC57SbnmzQCdG4ui
3097nLE/L9aUXdWeTFPron96DLA=
3098=2E+0
3099-----END PGP SIGNATURE-----
3100------------------------------------------------
Junio C Hamano8f62db92007-02-01 00:22:223101
Junio C Hamano35738e82008-01-07 07:55:463102See the linkgit:git-tag[1] command to learn how to create and verify tag
3103objects. (Note that linkgit:git-tag[1] can also be used to create
Junio C Hamano597ffcf2007-09-17 17:33:153104"lightweight tags", which are not tag objects at all, but just simple
Junio C Hamano9810d632007-09-24 01:05:343105references whose names begin with "refs/tags/").
Junio C Hamano597ffcf2007-09-17 17:33:153106
3107[[pack-files]]
3108How git stores objects efficiently: pack files
3109~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3110
3111Newly created objects are initially created in a file named after the
Junio C Hamano5f9a6f02009-04-06 08:26:563112object's SHA-1 hash (stored in .git/objects).
Junio C Hamano597ffcf2007-09-17 17:33:153113
3114Unfortunately this system becomes inefficient once a project has a
3115lot of objects. Try this on an old project:
3116
3117------------------------------------------------
3118$ git count-objects
31196930 objects, 47620 kilobytes
3120------------------------------------------------
3121
3122The first number is the number of objects which are kept in
3123individual files. The second is the amount of space taken up by
3124those "loose" objects.
3125
3126You can save space and make git faster by moving these loose objects in
3127to a "pack file", which stores a group of objects in an efficient
3128compressed format; the details of how pack files are formatted can be
3129found in link:technical/pack-format.txt[technical/pack-format.txt].
3130
3131To put the loose objects into a pack, just run git repack:
3132
3133------------------------------------------------
3134$ git repack
3135Generating pack...
3136Done counting 6020 objects.
3137Deltifying 6020 objects.
3138 100% (6020/6020) done
3139Writing 6020 objects.
3140 100% (6020/6020) done
3141Total 6020, written 6020 (delta 4070), reused 0 (delta 0)
3142Pack pack-3e54ad29d5b2e05838c75df582c65257b8d08e1c created.
3143------------------------------------------------
3144
3145You can then run
3146
3147------------------------------------------------
3148$ git prune
3149------------------------------------------------
3150
3151to remove any of the "loose" objects that are now contained in the
3152pack. This will also remove any unreferenced objects (which may be
Junio C Hamano5f9a6f02009-04-06 08:26:563153created when, for example, you use "git reset" to remove a commit).
Junio C Hamano597ffcf2007-09-17 17:33:153154You can verify that the loose objects are gone by looking at the
3155.git/objects directory or by running
3156
3157------------------------------------------------
3158$ git count-objects
31590 objects, 0 kilobytes
3160------------------------------------------------
3161
3162Although the object files are gone, any commands that refer to those
3163objects will work exactly as they did before.
3164
Junio C Hamano35738e82008-01-07 07:55:463165The linkgit:git-gc[1] command performs packing, pruning, and more for
Junio C Hamano597ffcf2007-09-17 17:33:153166you, so is normally the only high-level command you need.
3167
3168[[dangling-objects]]
3169Dangling objects
3170~~~~~~~~~~~~~~~~
3171
Junio C Hamano35738e82008-01-07 07:55:463172The linkgit:git-fsck[1] command will sometimes complain about dangling
Junio C Hamano597ffcf2007-09-17 17:33:153173objects. They are not a problem.
3174
3175The most common cause of dangling objects is that you've rebased a
3176branch, or you have pulled from somebody else who rebased a branch--see
3177<<cleaning-up-history>>. In that case, the old head of the original
3178branch still exists, as does everything it pointed to. The branch
3179pointer itself just doesn't, since you replaced it with another one.
3180
3181There are also other situations that cause dangling objects. For
Junio C Hamano5f9a6f02009-04-06 08:26:563182example, a "dangling blob" may arise because you did a "git add" of a
Junio C Hamano597ffcf2007-09-17 17:33:153183file, but then, before you actually committed it and made it part of the
3184bigger picture, you changed something else in that file and committed
Junio C Hamano764a6672007-10-23 01:23:313185that *updated* thing--the old state that you added originally ends up
Junio C Hamano597ffcf2007-09-17 17:33:153186not being pointed to by any commit or tree, so it's now a dangling blob
3187object.
3188
3189Similarly, when the "recursive" merge strategy runs, and finds that
3190there are criss-cross merges and thus more than one merge base (which is
3191fairly unusual, but it does happen), it will generate one temporary
3192midway tree (or possibly even more, if you had lots of criss-crossing
3193merges and more than two merge bases) as a temporary internal merge
3194base, and again, those are real objects, but the end result will not end
3195up pointing to them, so they end up "dangling" in your repository.
3196
3197Generally, dangling objects aren't anything to worry about. They can
3198even be very useful: if you screw something up, the dangling objects can
3199be how you recover your old tree (say, you did a rebase, and realized
Junio C Hamano764a6672007-10-23 01:23:313200that you really didn't want to--you can look at what dangling objects
Junio C Hamano597ffcf2007-09-17 17:33:153201you have, and decide to reset your head to some old dangling state).
3202
3203For commits, you can just use:
3204
3205------------------------------------------------
3206$ gitk <dangling-commit-sha-goes-here> --not --all
3207------------------------------------------------
3208
3209This asks for all the history reachable from the given commit but not
3210from any branch, tag, or other reference. If you decide it's something
3211you want, you can always create a new reference to it, e.g.,
3212
3213------------------------------------------------
3214$ git branch recovered-branch <dangling-commit-sha-goes-here>
3215------------------------------------------------
3216
3217For blobs and trees, you can't do the same, but you can still examine
3218them. You can just do
3219
3220------------------------------------------------
3221$ git show <dangling-blob/tree-sha-goes-here>
3222------------------------------------------------
3223
3224to show what the contents of the blob were (or, for a tree, basically
3225what the "ls" for that directory was), and that may give you some idea
3226of what the operation was that left that dangling object.
3227
3228Usually, dangling blobs and trees aren't very interesting. They're
3229almost always the result of either being a half-way mergebase (the blob
3230will often even have the conflict markers from a merge in it, if you
3231have had conflicting merges that you fixed up by hand), or simply
Junio C Hamano5f9a6f02009-04-06 08:26:563232because you interrupted a "git fetch" with ^C or something like that,
Junio C Hamano597ffcf2007-09-17 17:33:153233leaving _some_ of the new objects in the object database, but just
3234dangling and useless.
3235
3236Anyway, once you are sure that you're not interested in any dangling
3237state, you can just prune all unreachable objects:
3238
3239------------------------------------------------
3240$ git prune
3241------------------------------------------------
3242
3243and they'll be gone. But you should only run "git prune" on a quiescent
Junio C Hamano764a6672007-10-23 01:23:313244repository--it's kind of like doing a filesystem fsck recovery: you
Junio C Hamano597ffcf2007-09-17 17:33:153245don't want to do that while the filesystem is mounted.
3246
Junio C Hamano5f9a6f02009-04-06 08:26:563247(The same is true of "git fsck" itself, btw, but since
3248`git fsck` never actually *changes* the repository, it just reports
3249on what it found, `git fsck` itself is never 'dangerous' to run.
Junio C Hamano597ffcf2007-09-17 17:33:153250Running it while somebody is actually changing the repository can cause
3251confusing and scary messages, but it won't actually do anything bad. In
3252contrast, running "git prune" while somebody is actively changing the
3253repository is a *BAD* idea).
Junio C Hamano8f62db92007-02-01 00:22:223254
Junio C Hamanoce3650e2007-11-26 04:20:113255[[recovering-from-repository-corruption]]
3256Recovering from repository corruption
3257~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3258
3259By design, git treats data trusted to it with caution. However, even in
3260the absence of bugs in git itself, it is still possible that hardware or
3261operating system errors could corrupt data.
3262
3263The first defense against such problems is backups. You can back up a
3264git directory using clone, or just using cp, tar, or any other backup
3265mechanism.
3266
3267As a last resort, you can search for the corrupted objects and attempt
3268to replace them by hand. Back up your repository before attempting this
3269in case you corrupt things even more in the process.
3270
3271We'll assume that the problem is a single missing or corrupted blob,
Junio C Hamano878cc1e2007-12-14 08:35:133272which is sometimes a solvable problem. (Recovering missing trees and
Junio C Hamanoce3650e2007-11-26 04:20:113273especially commits is *much* harder).
3274
3275Before starting, verify that there is corruption, and figure out where
Junio C Hamano35738e82008-01-07 07:55:463276it is with linkgit:git-fsck[1]; this may be time-consuming.
Junio C Hamanoce3650e2007-11-26 04:20:113277
3278Assume the output looks like this:
3279
3280------------------------------------------------
Junio C Hamanofce7c7e2008-07-02 03:06:383281$ git fsck --full
Junio C Hamanoce3650e2007-11-26 04:20:113282broken link from tree 2d9263c6d23595e7cb2a21e5ebbb53655278dff8
3283 to blob 4b9458b3786228369c63936db65827de3cc06200
3284missing blob 4b9458b3786228369c63936db65827de3cc06200
3285------------------------------------------------
3286
3287(Typically there will be some "dangling object" messages too, but they
3288aren't interesting.)
3289
3290Now you know that blob 4b9458b3 is missing, and that the tree 2d9263c6
3291points to it. If you could find just one copy of that missing blob
3292object, possibly in some other repository, you could move it into
3293.git/objects/4b/9458b3... and be done. Suppose you can't. You can
Junio C Hamano35738e82008-01-07 07:55:463294still examine the tree that pointed to it with linkgit:git-ls-tree[1],
Junio C Hamanoce3650e2007-11-26 04:20:113295which might output something like:
3296
3297------------------------------------------------
3298$ git ls-tree 2d9263c6d23595e7cb2a21e5ebbb53655278dff8
3299100644 blob 8d14531846b95bfa3564b58ccfb7913a034323b8 .gitignore
3300100644 blob ebf9bf84da0aab5ed944264a5db2a65fe3a3e883 .mailmap
3301100644 blob ca442d313d86dc67e0a2e5d584b465bd382cbf5c COPYING
3302...
3303100644 blob 4b9458b3786228369c63936db65827de3cc06200 myfile
3304...
3305------------------------------------------------
3306
3307So now you know that the missing blob was the data for a file named
3308"myfile". And chances are you can also identify the directory--let's
3309say it's in "somedirectory". If you're lucky the missing copy might be
3310the same as the copy you have checked out in your working tree at
3311"somedirectory/myfile"; you can test whether that's right with
Junio C Hamano35738e82008-01-07 07:55:463312linkgit:git-hash-object[1]:
Junio C Hamanoce3650e2007-11-26 04:20:113313
3314------------------------------------------------
3315$ git hash-object -w somedirectory/myfile
3316------------------------------------------------
3317
3318which will create and store a blob object with the contents of
Junio C Hamano5f9a6f02009-04-06 08:26:563319somedirectory/myfile, and output the SHA-1 of that object. if you're
Junio C Hamanoce3650e2007-11-26 04:20:113320extremely lucky it might be 4b9458b3786228369c63936db65827de3cc06200, in
3321which case you've guessed right, and the corruption is fixed!
3322
3323Otherwise, you need more information. How do you tell which version of
3324the file has been lost?
3325
3326The easiest way to do this is with:
3327
3328------------------------------------------------
3329$ git log --raw --all --full-history -- somedirectory/myfile
3330------------------------------------------------
3331
3332Because you're asking for raw output, you'll now get something like
3333
3334------------------------------------------------
3335commit abc
3336Author:
3337Date:
3338...
3339:100644 100644 4b9458b... newsha... M somedirectory/myfile
3340
3341
3342commit xyz
3343Author:
3344Date:
3345
3346...
3347:100644 100644 oldsha... 4b9458b... M somedirectory/myfile
3348------------------------------------------------
3349
3350This tells you that the immediately preceding version of the file was
3351"newsha", and that the immediately following version was "oldsha".
3352You also know the commit messages that went with the change from oldsha
3353to 4b9458b and with the change from 4b9458b to newsha.
3354
3355If you've been committing small enough changes, you may now have a good
3356shot at reconstructing the contents of the in-between state 4b9458b.
3357
3358If you can do that, you can now recreate the missing object with
3359
3360------------------------------------------------
3361$ git hash-object -w <recreated-file>
3362------------------------------------------------
3363
3364and your repository is good again!
3365
3366(Btw, you could have ignored the fsck, and started with doing a
3367
3368------------------------------------------------
3369$ git log --raw --all
3370------------------------------------------------
3371
3372and just looked for the sha of the missing object (4b9458b..) in that
3373whole thing. It's up to you - git does *have* a lot of information, it is
3374just missing one particular blob version.
3375
Junio C Hamano3d30fd52007-05-08 00:32:533376[[the-index]]
Junio C Hamano597ffcf2007-09-17 17:33:153377The index
3378-----------
Junio C Hamano8f62db92007-02-01 00:22:223379
Junio C Hamano597ffcf2007-09-17 17:33:153380The index is a binary file (generally kept in .git/index) containing a
Junio C Hamano5f9a6f02009-04-06 08:26:563381sorted list of path names, each with permissions and the SHA-1 of a blob
Junio C Hamano35738e82008-01-07 07:55:463382object; linkgit:git-ls-files[1] can show you the contents of the index:
Junio C Hamano8f62db92007-02-01 00:22:223383
Junio C Hamano597ffcf2007-09-17 17:33:153384-------------------------------------------------
3385$ git ls-files --stage
3386100644 63c918c667fa005ff12ad89437f2fdc80926e21c 0 .gitignore
3387100644 5529b198e8d14decbe4ad99db3f7fb632de0439d 0 .mailmap
3388100644 6ff87c4664981e4397625791c8ea3bbb5f2279a3 0 COPYING
3389100644 a37b2152bd26be2c2289e1f57a292534a51a93c7 0 Documentation/.gitignore
3390100644 fbefe9a45b00a54b58d94d06eca48b03d40a50e0 0 Documentation/Makefile
3391...
3392100644 2511aef8d89ab52be5ec6a5e46236b4b6bcd07ea 0 xdiff/xtypes.h
3393100644 2ade97b2574a9f77e7ae4002a4e07a6a38e46d07 0 xdiff/xutils.c
3394100644 d5de8292e05e7c36c4b68857c1cf9855e3d2f70a 0 xdiff/xutils.h
3395-------------------------------------------------
Junio C Hamano8f62db92007-02-01 00:22:223396
Junio C Hamano597ffcf2007-09-17 17:33:153397Note that in older documentation you may see the index called the
3398"current directory cache" or just the "cache". It has three important
3399properties:
Junio C Hamano8f62db92007-02-01 00:22:223400
Junio C Hamano597ffcf2007-09-17 17:33:1534011. The index contains all the information necessary to generate a single
3402(uniquely determined) tree object.
3403+
Junio C Hamano35738e82008-01-07 07:55:463404For example, running linkgit:git-commit[1] generates this tree object
Junio C Hamano597ffcf2007-09-17 17:33:153405from the index, stores it in the object database, and uses it as the
3406tree object associated with the new commit.
Junio C Hamano8f62db92007-02-01 00:22:223407
Junio C Hamano597ffcf2007-09-17 17:33:1534082. The index enables fast comparisons between the tree object it defines
3409and the working tree.
3410+
3411It does this by storing some additional data for each entry (such as
3412the last modified time). This data is not displayed above, and is not
3413stored in the created tree object, but it can be used to determine
3414quickly which files in the working directory differ from what was
3415stored in the index, and thus save git from having to read all of the
3416data from such files to look for changes.
Junio C Hamano8f62db92007-02-01 00:22:223417
Junio C Hamano597ffcf2007-09-17 17:33:1534183. It can efficiently represent information about merge conflicts
3419between different tree objects, allowing each pathname to be
Junio C Hamano8f62db92007-02-01 00:22:223420associated with sufficient information about the trees involved that
Junio C Hamano597ffcf2007-09-17 17:33:153421you can create a three-way merge between them.
3422+
3423We saw in <<conflict-resolution>> that during a merge the index can
3424store multiple versions of a single file (called "stages"). The third
Junio C Hamano35738e82008-01-07 07:55:463425column in the linkgit:git-ls-files[1] output above is the stage
Junio C Hamano597ffcf2007-09-17 17:33:153426number, and will take on values other than 0 for files with merge
3427conflicts.
Junio C Hamano8f62db92007-02-01 00:22:223428
Junio C Hamano597ffcf2007-09-17 17:33:153429The index is thus a sort of temporary staging area, which is filled with
3430a tree which you are in the process of working on.
Junio C Hamano8f62db92007-02-01 00:22:223431
Junio C Hamano597ffcf2007-09-17 17:33:153432If you blow the index away entirely, you generally haven't lost any
3433information as long as you have the name of the tree that it described.
Junio C Hamano8f62db92007-02-01 00:22:223434
Junio C Hamano9810d632007-09-24 01:05:343435[[submodules]]
3436Submodules
3437==========
3438
Junio C Hamano4fd58d42007-09-30 00:51:143439Large projects are often composed of smaller, self-contained modules. For
3440example, an embedded Linux distribution's source tree would include every
3441piece of software in the distribution with some local modifications; a movie
3442player might need to build against a specific, known-working version of a
3443decompression library; several independent programs might all share the same
3444build scripts.
Junio C Hamano9810d632007-09-24 01:05:343445
Junio C Hamano4fd58d42007-09-30 00:51:143446With centralized revision control systems this is often accomplished by
3447including every module in one single repository. Developers can check out
3448all modules or only the modules they need to work with. They can even modify
3449files across several modules in a single commit while moving things around
3450or updating APIs and translations.
3451
3452Git does not allow partial checkouts, so duplicating this approach in Git
3453would force developers to keep a local copy of modules they are not
3454interested in touching. Commits in an enormous checkout would be slower
3455than you'd expect as Git would have to scan every directory for changes.
3456If modules have a lot of local history, clones would take forever.
3457
3458On the plus side, distributed revision control systems can much better
3459integrate with external sources. In a centralized model, a single arbitrary
3460snapshot of the external project is exported from its own revision control
3461and then imported into the local revision control on a vendor branch. All
3462the history is hidden. With distributed revision control you can clone the
3463entire external history and much more easily follow development and re-merge
3464local changes.
3465
3466Git's submodule support allows a repository to contain, as a subdirectory, a
3467checkout of an external project. Submodules maintain their own identity;
3468the submodule support just stores the submodule repository location and
3469commit ID, so other developers who clone the containing project
3470("superproject") can easily clone all the submodules at the same revision.
3471Partial checkouts of the superproject are possible: you can tell Git to
3472clone none, some or all of the submodules.
3473
Junio C Hamano35738e82008-01-07 07:55:463474The linkgit:git-submodule[1] command is available since Git 1.5.3. Users
Junio C Hamano4fd58d42007-09-30 00:51:143475with Git 1.5.2 can look up the submodule commits in the repository and
3476manually check them out; earlier versions won't recognize the submodules at
3477all.
Junio C Hamano9810d632007-09-24 01:05:343478
3479To see how submodule support works, create (for example) four example
3480repositories that can be used later as a submodule:
3481
3482-------------------------------------------------
3483$ mkdir ~/git
3484$ cd ~/git
3485$ for i in a b c d
3486do
3487mkdir $i
3488cd $i
3489git init
3490echo "module $i" > $i.txt
3491git add $i.txt
3492git commit -m "Initial commit, submodule $i"
3493cd ..
3494done
3495-------------------------------------------------
3496
3497Now create the superproject and add all the submodules:
3498
3499-------------------------------------------------
3500$ mkdir super
3501$ cd super
3502$ git init
3503$ for i in a b c d
3504do
Junio C Hamano7f80ae82008-07-30 18:31:353505git submodule add ~/git/$i $i
Junio C Hamano9810d632007-09-24 01:05:343506done
3507-------------------------------------------------
3508
3509NOTE: Do not use local URLs here if you plan to publish your superproject!
3510
Junio C Hamano5f9a6f02009-04-06 08:26:563511See what files `git submodule` created:
Junio C Hamano9810d632007-09-24 01:05:343512
3513-------------------------------------------------
3514$ ls -a
3515. .. .git .gitmodules a b c d
3516-------------------------------------------------
3517
Junio C Hamano5f9a6f02009-04-06 08:26:563518The `git submodule add <repo> <path>` command does a couple of things:
Junio C Hamano9810d632007-09-24 01:05:343519
Junio C Hamano7f80ae82008-07-30 18:31:353520- It clones the submodule from <repo> to the given <path> under the
3521 current directory and by default checks out the master branch.
Junio C Hamano35738e82008-01-07 07:55:463522- It adds the submodule's clone path to the linkgit:gitmodules[5] file and
Junio C Hamano4fd58d42007-09-30 00:51:143523 adds this file to the index, ready to be committed.
Junio C Hamano9810d632007-09-24 01:05:343524- It adds the submodule's current commit ID to the index, ready to be
3525 committed.
3526
3527Commit the superproject:
3528
3529-------------------------------------------------
3530$ git commit -m "Add submodules a, b, c and d."
3531-------------------------------------------------
3532
3533Now clone the superproject:
3534
3535-------------------------------------------------
3536$ cd ..
3537$ git clone super cloned
3538$ cd cloned
3539-------------------------------------------------
3540
3541The submodule directories are there, but they're empty:
3542
3543-------------------------------------------------
3544$ ls -a a
3545. ..
3546$ git submodule status
3547-d266b9873ad50488163457f025db7cdd9683d88b a
3548-e81d457da15309b4fef4249aba9b50187999670d b
3549-c1536a972b9affea0f16e0680ba87332dc059146 c
3550-d96249ff5d57de5de093e6baff9e0aafa5276a74 d
3551-------------------------------------------------
3552
3553NOTE: The commit object names shown above would be different for you, but they
3554should match the HEAD commit object names of your repositories. You can check
3555it by running `git ls-remote ../a`.
3556
3557Pulling down the submodules is a two-step process. First run `git submodule
3558init` to add the submodule repository URLs to `.git/config`:
3559
3560-------------------------------------------------
3561$ git submodule init
3562-------------------------------------------------
3563
Junio C Hamano5f9a6f02009-04-06 08:26:563564Now use `git submodule update` to clone the repositories and check out the
Junio C Hamano9810d632007-09-24 01:05:343565commits specified in the superproject:
3566
3567-------------------------------------------------
3568$ git submodule update
3569$ cd a
3570$ ls -a
3571. .. .git a.txt
3572-------------------------------------------------
3573
Junio C Hamano5f9a6f02009-04-06 08:26:563574One major difference between `git submodule update` and `git submodule add` is
3575that `git submodule update` checks out a specific commit, rather than the tip
Junio C Hamano9810d632007-09-24 01:05:343576of a branch. It's like checking out a tag: the head is detached, so you're not
3577working on a branch.
3578
3579-------------------------------------------------
3580$ git branch
3581* (no branch)
3582 master
3583-------------------------------------------------
3584
3585If you want to make a change within a submodule and you have a detached head,
3586then you should create or checkout a branch, make your changes, publish the
3587change within the submodule, and then update the superproject to reference the
3588new commit:
3589
3590-------------------------------------------------
3591$ git checkout master
3592-------------------------------------------------
3593
3594or
3595
3596-------------------------------------------------
3597$ git checkout -b fix-up
3598-------------------------------------------------
3599
3600then
3601
3602-------------------------------------------------
3603$ echo "adding a line again" >> a.txt
3604$ git commit -a -m "Updated the submodule from within the superproject."
3605$ git push
3606$ cd ..
3607$ git diff
3608diff --git a/a b/a
3609index d266b98..261dfac 160000
3610--- a/a
3611+++ b/a
3612@@ -1 +1 @@
3613-Subproject commit d266b9873ad50488163457f025db7cdd9683d88b
3614+Subproject commit 261dfac35cb99d380eb966e102c1197139f7fa24
3615$ git add a
3616$ git commit -m "Updated submodule a."
3617$ git push
3618-------------------------------------------------
3619
3620You have to run `git submodule update` after `git pull` if you want to update
3621submodules, too.
3622
3623Pitfalls with submodules
3624------------------------
3625
3626Always publish the submodule change before publishing the change to the
3627superproject that references it. If you forget to publish the submodule change,
3628others won't be able to clone the repository:
3629
3630-------------------------------------------------
3631$ cd ~/git/super/a
3632$ echo i added another line to this file >> a.txt
3633$ git commit -a -m "doing it wrong this time"
3634$ cd ..
3635$ git add a
3636$ git commit -m "Updated submodule a again."
3637$ git push
3638$ cd ~/git/cloned
3639$ git pull
3640$ git submodule update
3641error: pathspec '261dfac35cb99d380eb966e102c1197139f7fa24' did not match any file(s) known to git.
3642Did you forget to 'git add'?
3643Unable to checkout '261dfac35cb99d380eb966e102c1197139f7fa24' in submodule path 'a'
3644-------------------------------------------------
3645
Junio C Hamano2b186d82010-02-02 07:17:343646In older git versions it could be easily forgotten to commit new or modified
3647files in a submodule, which silently leads to similar problems as not pushing
3648the submodule changes. Starting with git 1.7.0 both "git status" and "git diff"
3649in the superproject show submodules as modified when they contain new or
3650modified files to protect against accidentally committing such a state. "git
3651diff" will also add a "-dirty" to the work tree side when generating patch
3652output or used with the --submodule option:
3653
3654-------------------------------------------------
3655$ git diff
3656diff --git a/sub b/sub
3657--- a/sub
3658+++ b/sub
3659@@ -1 +1 @@
3660-Subproject commit 3f356705649b5d566d97ff843cf193359229a453
3661+Subproject commit 3f356705649b5d566d97ff843cf193359229a453-dirty
3662$ git diff --submodule
3663Submodule sub 3f35670..3f35670-dirty:
3664-------------------------------------------------
3665
Junio C Hamano9810d632007-09-24 01:05:343666You also should not rewind branches in a submodule beyond commits that were
3667ever recorded in any superproject.
3668
3669It's not safe to run `git submodule update` if you've made and committed
3670changes within a submodule without checking out a branch first. They will be
3671silently overwritten:
3672
3673-------------------------------------------------
3674$ cat a.txt
3675module a
3676$ echo line added from private2 >> a.txt
3677$ git commit -a -m "line added inside private2"
3678$ cd ..
3679$ git submodule update
3680Submodule path 'a': checked out 'd266b9873ad50488163457f025db7cdd9683d88b'
3681$ cd a
3682$ cat a.txt
3683module a
3684-------------------------------------------------
3685
3686NOTE: The changes are still visible in the submodule's reflog.
3687
3688This is not the case if you did not commit your changes.
3689
Junio C Hamano597ffcf2007-09-17 17:33:153690[[low-level-operations]]
3691Low-level git operations
3692========================
Junio C Hamano8f62db92007-02-01 00:22:223693
Junio C Hamano597ffcf2007-09-17 17:33:153694Many of the higher-level commands were originally implemented as shell
3695scripts using a smaller core of low-level git commands. These can still
3696be useful when doing unusual things with git, or just as a way to
3697understand its inner workings.
3698
3699[[object-manipulation]]
3700Object access and manipulation
3701------------------------------
3702
Junio C Hamano35738e82008-01-07 07:55:463703The linkgit:git-cat-file[1] command can show the contents of any object,
3704though the higher-level linkgit:git-show[1] is usually more useful.
Junio C Hamano597ffcf2007-09-17 17:33:153705
Junio C Hamano35738e82008-01-07 07:55:463706The linkgit:git-commit-tree[1] command allows constructing commits with
Junio C Hamano597ffcf2007-09-17 17:33:153707arbitrary parents and trees.
3708
Junio C Hamano35738e82008-01-07 07:55:463709A tree can be created with linkgit:git-write-tree[1] and its data can be
3710accessed by linkgit:git-ls-tree[1]. Two trees can be compared with
3711linkgit:git-diff-tree[1].
Junio C Hamano597ffcf2007-09-17 17:33:153712
Junio C Hamano35738e82008-01-07 07:55:463713A tag is created with linkgit:git-mktag[1], and the signature can be
3714verified by linkgit:git-verify-tag[1], though it is normally simpler to
3715use linkgit:git-tag[1] for both.
Junio C Hamano8f62db92007-02-01 00:22:223716
Junio C Hamano3d30fd52007-05-08 00:32:533717[[the-workflow]]
Junio C Hamano8f62db92007-02-01 00:22:223718The Workflow
3719------------
3720
Junio C Hamano35738e82008-01-07 07:55:463721High-level operations such as linkgit:git-commit[1],
3722linkgit:git-checkout[1] and linkgit:git-reset[1] work by moving data
Junio C Hamano764a6672007-10-23 01:23:313723between the working tree, the index, and the object database. Git
3724provides low-level operations which perform each of these steps
3725individually.
Junio C Hamano597ffcf2007-09-17 17:33:153726
Junio C Hamano8f62db92007-02-01 00:22:223727Generally, all "git" operations work on the index file. Some operations
3728work *purely* on the index file (showing the current state of the
Junio C Hamano597ffcf2007-09-17 17:33:153729index), but most operations move data between the index file and either
3730the database or the working directory. Thus there are four main
3731combinations:
Junio C Hamano8f62db92007-02-01 00:22:223732
Junio C Hamano3d30fd52007-05-08 00:32:533733[[working-directory-to-index]]
Junio C Hamano8f62db92007-02-01 00:22:223734working directory -> index
3735~~~~~~~~~~~~~~~~~~~~~~~~~~
3736
Junio C Hamano35738e82008-01-07 07:55:463737The linkgit:git-update-index[1] command updates the index with
Junio C Hamano597ffcf2007-09-17 17:33:153738information from the working directory. You generally update the
3739index information by just specifying the filename you want to update,
3740like so:
Junio C Hamano8f62db92007-02-01 00:22:223741
3742-------------------------------------------------
Junio C Hamano597ffcf2007-09-17 17:33:153743$ git update-index filename
Junio C Hamano8f62db92007-02-01 00:22:223744-------------------------------------------------
3745
3746but to avoid common mistakes with filename globbing etc, the command
3747will not normally add totally new entries or remove old entries,
3748i.e. it will normally just update existing cache entries.
3749
3750To tell git that yes, you really do realize that certain files no
3751longer exist, or that new files should be added, you
3752should use the `--remove` and `--add` flags respectively.
3753
3754NOTE! A `--remove` flag does 'not' mean that subsequent filenames will
3755necessarily be removed: if the files still exist in your directory
3756structure, the index will be updated with their new status, not
Junio C Hamano774239c2007-12-01 01:57:433757removed. The only thing `--remove` means is that update-index will be
Junio C Hamano8f62db92007-02-01 00:22:223758considering a removed file to be a valid thing, and if the file really
3759does not exist any more, it will update the index accordingly.
3760
Junio C Hamanoba4b9282008-07-06 05:20:313761As a special case, you can also do `git update-index --refresh`, which
Junio C Hamano8f62db92007-02-01 00:22:223762will refresh the "stat" information of each index to match the current
3763stat information. It will 'not' update the object status itself, and
3764it will only update the fields that are used to quickly test whether
3765an object still matches its old backing store object.
3766
Junio C Hamano35738e82008-01-07 07:55:463767The previously introduced linkgit:git-add[1] is just a wrapper for
3768linkgit:git-update-index[1].
Junio C Hamano597ffcf2007-09-17 17:33:153769
Junio C Hamano3d30fd52007-05-08 00:32:533770[[index-to-object-database]]
Junio C Hamano8f62db92007-02-01 00:22:223771index -> object database
3772~~~~~~~~~~~~~~~~~~~~~~~~
3773
3774You write your current index file to a "tree" object with the program
3775
3776-------------------------------------------------
Junio C Hamano597ffcf2007-09-17 17:33:153777$ git write-tree
Junio C Hamano8f62db92007-02-01 00:22:223778-------------------------------------------------
3779
Junio C Hamano764a6672007-10-23 01:23:313780that doesn't come with any options--it will just write out the
Junio C Hamano8f62db92007-02-01 00:22:223781current index into the set of tree objects that describe that state,
3782and it will return the name of the resulting top-level tree. You can
3783use that tree to re-generate the index at any time by going in the
3784other direction:
3785
Junio C Hamano3d30fd52007-05-08 00:32:533786[[object-database-to-index]]
Junio C Hamano8f62db92007-02-01 00:22:223787object database -> index
3788~~~~~~~~~~~~~~~~~~~~~~~~
3789
3790You read a "tree" file from the object database, and use that to
Junio C Hamano764a6672007-10-23 01:23:313791populate (and overwrite--don't do this if your index contains any
Junio C Hamano8f62db92007-02-01 00:22:223792unsaved state that you might want to restore later!) your current
3793index. Normal operation is just
3794
3795-------------------------------------------------
Junio C Hamano5f9a6f02009-04-06 08:26:563796$ git read-tree <SHA-1 of tree>
Junio C Hamano8f62db92007-02-01 00:22:223797-------------------------------------------------
3798
3799and your index file will now be equivalent to the tree that you saved
3800earlier. However, that is only your 'index' file: your working
3801directory contents have not been modified.
3802
Junio C Hamano3d30fd52007-05-08 00:32:533803[[index-to-working-directory]]
Junio C Hamano8f62db92007-02-01 00:22:223804index -> working directory
3805~~~~~~~~~~~~~~~~~~~~~~~~~~
3806
3807You update your working directory from the index by "checking out"
3808files. This is not a very common operation, since normally you'd just
3809keep your files updated, and rather than write to your working
3810directory, you'd tell the index files about the changes in your
Junio C Hamano5f9a6f02009-04-06 08:26:563811working directory (i.e. `git update-index`).
Junio C Hamano8f62db92007-02-01 00:22:223812
3813However, if you decide to jump to a new version, or check out somebody
3814else's version, or just restore a previous tree, you'd populate your
3815index file with read-tree, and then you need to check out the result
3816with
3817
3818-------------------------------------------------
Junio C Hamanofce7c7e2008-07-02 03:06:383819$ git checkout-index filename
Junio C Hamano8f62db92007-02-01 00:22:223820-------------------------------------------------
3821
3822or, if you want to check out all of the index, use `-a`.
3823
Junio C Hamano5f9a6f02009-04-06 08:26:563824NOTE! `git checkout-index` normally refuses to overwrite old files, so
Junio C Hamano8f62db92007-02-01 00:22:223825if you have an old version of the tree already checked out, you will
3826need to use the "-f" flag ('before' the "-a" flag or the filename) to
3827'force' the checkout.
3828
3829
3830Finally, there are a few odds and ends which are not purely moving
3831from one representation to the other:
3832
Junio C Hamano3d30fd52007-05-08 00:32:533833[[tying-it-all-together]]
Junio C Hamano8f62db92007-02-01 00:22:223834Tying it all together
3835~~~~~~~~~~~~~~~~~~~~~
3836
Junio C Hamanoba4b9282008-07-06 05:20:313837To commit a tree you have instantiated with "git write-tree", you'd
Junio C Hamano8f62db92007-02-01 00:22:223838create a "commit" object that refers to that tree and the history
Junio C Hamano764a6672007-10-23 01:23:313839behind it--most notably the "parent" commits that preceded it in
Junio C Hamano8f62db92007-02-01 00:22:223840history.
3841
3842Normally a "commit" has one parent: the previous state of the tree
3843before a certain change was made. However, sometimes it can have two
3844or more parent commits, in which case we call it a "merge", due to the
3845fact that such a commit brings together ("merges") two or more
3846previous states represented by other commits.
3847
3848In other words, while a "tree" represents a particular directory state
3849of a working directory, a "commit" represents that state in "time",
3850and explains how we got there.
3851
3852You create a commit object by giving it the tree that describes the
3853state at the time of the commit, and a list of parents:
3854
3855-------------------------------------------------
Junio C Hamanod2179ef2010-10-22 04:12:173856$ git commit-tree <tree> -p <parent> [(-p <parent2>)...]
Junio C Hamano8f62db92007-02-01 00:22:223857-------------------------------------------------
3858
3859and then giving the reason for the commit on stdin (either through
3860redirection from a pipe or file, or by just typing it at the tty).
3861
Junio C Hamano5f9a6f02009-04-06 08:26:563862`git commit-tree` will return the name of the object that represents
Junio C Hamano8f62db92007-02-01 00:22:223863that commit, and you should save it away for later use. Normally,
3864you'd commit a new `HEAD` state, and while git doesn't care where you
3865save the note about that state, in practice we tend to just write the
3866result to the file pointed at by `.git/HEAD`, so that we can always see
3867what the last committed state was.
3868
3869Here is an ASCII art by Jon Loeliger that illustrates how
3870various pieces fit together.
3871
3872------------
3873
3874 commit-tree
3875 commit obj
3876 +----+
3877 | |
3878 | |
3879 V V
3880 +-----------+
3881 | Object DB |
3882 | Backing |
3883 | Store |
3884 +-----------+
3885 ^
3886 write-tree | |
3887 tree obj | |
3888 | | read-tree
3889 | | tree obj
3890 V
3891 +-----------+
3892 | Index |
3893 | "cache" |
3894 +-----------+
3895 update-index ^
3896 blob obj | |
3897 | |
3898 checkout-index -u | | checkout-index
3899 stat | | blob obj
3900 V
3901 +-----------+
3902 | Working |
3903 | Directory |
3904 +-----------+
3905
3906------------
3907
3908
Junio C Hamano3d30fd52007-05-08 00:32:533909[[examining-the-data]]
Junio C Hamano8f62db92007-02-01 00:22:223910Examining the data
3911------------------
3912
3913You can examine the data represented in the object database and the
3914index with various helper tools. For every object, you can use
Junio C Hamano35738e82008-01-07 07:55:463915linkgit:git-cat-file[1] to examine details about the
Junio C Hamano8f62db92007-02-01 00:22:223916object:
3917
3918-------------------------------------------------
Junio C Hamanofce7c7e2008-07-02 03:06:383919$ git cat-file -t <objectname>
Junio C Hamano8f62db92007-02-01 00:22:223920-------------------------------------------------
3921
3922shows the type of the object, and once you have the type (which is
3923usually implicit in where you find the object), you can use
3924
3925-------------------------------------------------
Junio C Hamanofce7c7e2008-07-02 03:06:383926$ git cat-file blob|tree|commit|tag <objectname>
Junio C Hamano8f62db92007-02-01 00:22:223927-------------------------------------------------
3928
3929to show its contents. NOTE! Trees have binary content, and as a result
3930there is a special helper for showing that content, called
Junio C Hamano5f9a6f02009-04-06 08:26:563931`git ls-tree`, which turns the binary content into a more easily
Junio C Hamano8f62db92007-02-01 00:22:223932readable form.
3933
3934It's especially instructive to look at "commit" objects, since those
3935tend to be small and fairly self-explanatory. In particular, if you
3936follow the convention of having the top commit name in `.git/HEAD`,
3937you can do
3938
3939-------------------------------------------------
Junio C Hamanofce7c7e2008-07-02 03:06:383940$ git cat-file commit HEAD
Junio C Hamano8f62db92007-02-01 00:22:223941-------------------------------------------------
3942
3943to see what the top commit was.
3944
Junio C Hamano3d30fd52007-05-08 00:32:533945[[merging-multiple-trees]]
Junio C Hamano8f62db92007-02-01 00:22:223946Merging multiple trees
3947----------------------
3948
3949Git helps you do a three-way merge, which you can expand to n-way by
3950repeating the merge procedure arbitrary times until you finally
3951"commit" the state. The normal situation is that you'd only do one
3952three-way merge (two parents), and commit it, but if you like to, you
3953can do multiple parents in one go.
3954
3955To do a three-way merge, you need the two sets of "commit" objects
3956that you want to merge, use those to find the closest common parent (a
3957third "commit" object), and then use those commit objects to find the
3958state of the directory ("tree" object) at these points.
3959
3960To get the "base" for the merge, you first look up the common parent
3961of two commits with
3962
3963-------------------------------------------------
Junio C Hamanofce7c7e2008-07-02 03:06:383964$ git merge-base <commit1> <commit2>
Junio C Hamano8f62db92007-02-01 00:22:223965-------------------------------------------------
3966
3967which will return you the commit they are both based on. You should
3968now look up the "tree" objects of those commits, which you can easily
3969do with (for example)
3970
3971-------------------------------------------------
Junio C Hamanofce7c7e2008-07-02 03:06:383972$ git cat-file commit <commitname> | head -1
Junio C Hamano8f62db92007-02-01 00:22:223973-------------------------------------------------
3974
3975since the tree object information is always the first line in a commit
3976object.
3977
3978Once you know the three trees you are going to merge (the one "original"
Junio C Hamano3d30fd52007-05-08 00:32:533979tree, aka the common tree, and the two "result" trees, aka the branches
Junio C Hamano8f62db92007-02-01 00:22:223980you want to merge), you do a "merge" read into the index. This will
3981complain if it has to throw away your old index contents, so you should
Junio C Hamano764a6672007-10-23 01:23:313982make sure that you've committed those--in fact you would normally
Junio C Hamano8f62db92007-02-01 00:22:223983always do a merge against your last commit (which should thus match what
3984you have in your current index anyway).
3985
3986To do the merge, do
3987
3988-------------------------------------------------
Junio C Hamanofce7c7e2008-07-02 03:06:383989$ git read-tree -m -u <origtree> <yourtree> <targettree>
Junio C Hamano8f62db92007-02-01 00:22:223990-------------------------------------------------
3991
3992which will do all trivial merge operations for you directly in the
3993index file, and you can just write the result out with
Junio C Hamanoba4b9282008-07-06 05:20:313994`git write-tree`.
Junio C Hamano8f62db92007-02-01 00:22:223995
3996
Junio C Hamano3d30fd52007-05-08 00:32:533997[[merging-multiple-trees-2]]
Junio C Hamano8f62db92007-02-01 00:22:223998Merging multiple trees, continued
3999---------------------------------
4000
4001Sadly, many merges aren't trivial. If there are files that have
Junio C Hamano764a6672007-10-23 01:23:314002been added, moved or removed, or if both branches have modified the
Junio C Hamano8f62db92007-02-01 00:22:224003same file, you will be left with an index tree that contains "merge
4004entries" in it. Such an index tree can 'NOT' be written out to a tree
4005object, and you will have to resolve any such merge clashes using
4006other tools before you can write out the result.
4007
Junio C Hamanofce7c7e2008-07-02 03:06:384008You can examine such index state with `git ls-files --unmerged`
Junio C Hamano8f62db92007-02-01 00:22:224009command. An example:
4010
4011------------------------------------------------
Junio C Hamanofce7c7e2008-07-02 03:06:384012$ git read-tree -m $orig HEAD $target
4013$ git ls-files --unmerged
Junio C Hamano8f62db92007-02-01 00:22:224014100644 263414f423d0e4d70dae8fe53fa34614ff3e2860 1 hello.c
4015100644 06fa6a24256dc7e560efa5687fa84b51f0263c3a 2 hello.c
4016100644 cc44c73eb783565da5831b4d820c962954019b69 3 hello.c
4017------------------------------------------------
4018
Junio C Hamanofce7c7e2008-07-02 03:06:384019Each line of the `git ls-files --unmerged` output begins with
Junio C Hamano5f9a6f02009-04-06 08:26:564020the blob mode bits, blob SHA-1, 'stage number', and the
Junio C Hamano8f62db92007-02-01 00:22:224021filename. The 'stage number' is git's way to say which tree it
4022came from: stage 1 corresponds to `$orig` tree, stage 2 `HEAD`
4023tree, and stage3 `$target` tree.
4024
4025Earlier we said that trivial merges are done inside
Junio C Hamano5f9a6f02009-04-06 08:26:564026`git read-tree -m`. For example, if the file did not change
Junio C Hamano8f62db92007-02-01 00:22:224027from `$orig` to `HEAD` nor `$target`, or if the file changed
4028from `$orig` to `HEAD` and `$orig` to `$target` the same way,
4029obviously the final outcome is what is in `HEAD`. What the
4030above example shows is that file `hello.c` was changed from
4031`$orig` to `HEAD` and `$orig` to `$target` in a different way.
4032You could resolve this by running your favorite 3-way merge
Junio C Hamano3d30fd52007-05-08 00:32:534033program, e.g. `diff3`, `merge`, or git's own merge-file, on
4034the blob objects from these three stages yourself, like this:
Junio C Hamano8f62db92007-02-01 00:22:224035
4036------------------------------------------------
Junio C Hamanofce7c7e2008-07-02 03:06:384037$ git cat-file blob 263414f... >hello.c~1
4038$ git cat-file blob 06fa6a2... >hello.c~2
4039$ git cat-file blob cc44c73... >hello.c~3
Junio C Hamano3d30fd52007-05-08 00:32:534040$ git merge-file hello.c~2 hello.c~1 hello.c~3
Junio C Hamano8f62db92007-02-01 00:22:224041------------------------------------------------
4042
4043This would leave the merge result in `hello.c~2` file, along
4044with conflict markers if there are conflicts. After verifying
4045the merge result makes sense, you can tell git what the final
4046merge result for this file is by:
4047
4048-------------------------------------------------
4049$ mv -f hello.c~2 hello.c
Junio C Hamanofce7c7e2008-07-02 03:06:384050$ git update-index hello.c
Junio C Hamano8f62db92007-02-01 00:22:224051-------------------------------------------------
4052
Junio C Hamano5f9a6f02009-04-06 08:26:564053When a path is in the "unmerged" state, running `git update-index` for
Junio C Hamano8f62db92007-02-01 00:22:224054that path tells git to mark the path resolved.
4055
4056The above is the description of a git merge at the lowest level,
4057to help you understand what conceptually happens under the hood.
Junio C Hamano5f9a6f02009-04-06 08:26:564058In practice, nobody, not even git itself, runs `git cat-file` three times
4059for this. There is a `git merge-index` program that extracts the
Junio C Hamano8f62db92007-02-01 00:22:224060stages to temporary files and calls a "merge" script on it:
4061
4062-------------------------------------------------
Junio C Hamanofce7c7e2008-07-02 03:06:384063$ git merge-index git-merge-one-file hello.c
Junio C Hamano8f62db92007-02-01 00:22:224064-------------------------------------------------
4065
Junio C Hamano5f9a6f02009-04-06 08:26:564066and that is what higher level `git merge -s resolve` is implemented with.
Junio C Hamano8f62db92007-02-01 00:22:224067
Junio C Hamano597ffcf2007-09-17 17:33:154068[[hacking-git]]
4069Hacking git
4070===========
Junio C Hamano8f62db92007-02-01 00:22:224071
Junio C Hamano597ffcf2007-09-17 17:33:154072This chapter covers internal details of the git implementation which
4073probably only git developers need to understand.
Junio C Hamano8f62db92007-02-01 00:22:224074
Junio C Hamano597ffcf2007-09-17 17:33:154075[[object-details]]
4076Object storage format
4077---------------------
Junio C Hamano8f62db92007-02-01 00:22:224078
Junio C Hamano597ffcf2007-09-17 17:33:154079All objects have a statically determined "type" which identifies the
4080format of the object (i.e. how it is used, and how it can refer to other
4081objects). There are currently four different object types: "blob",
4082"tree", "commit", and "tag".
Junio C Hamano8f62db92007-02-01 00:22:224083
Junio C Hamano597ffcf2007-09-17 17:33:154084Regardless of object type, all objects share the following
4085characteristics: they are all deflated with zlib, and have a header
4086that not only specifies their type, but also provides size information
Junio C Hamano5f9a6f02009-04-06 08:26:564087about the data in the object. It's worth noting that the SHA-1 hash
Junio C Hamano597ffcf2007-09-17 17:33:154088that is used to name the object is the hash of the original data
4089plus this header, so `sha1sum` 'file' does not match the object name
4090for 'file'.
4091(Historical note: in the dawn of the age of git the hash
Junio C Hamano5f9a6f02009-04-06 08:26:564092was the SHA-1 of the 'compressed' object.)
Junio C Hamano8f62db92007-02-01 00:22:224093
Junio C Hamano597ffcf2007-09-17 17:33:154094As a result, the general consistency of an object can always be tested
4095independently of the contents or the type of the object: all objects can
4096be validated by verifying that (a) their hashes match the content of the
4097file and (b) the object successfully inflates to a stream of bytes that
4098forms a sequence of <ascii type without space> {plus} <space> {plus} <ascii decimal
4099size> {plus} <byte\0> {plus} <binary object data>.
Junio C Hamano8f62db92007-02-01 00:22:224100
Junio C Hamano597ffcf2007-09-17 17:33:154101The structured objects can further have their structure and
4102connectivity to other objects verified. This is generally done with
Junio C Hamano5f9a6f02009-04-06 08:26:564103the `git fsck` program, which generates a full dependency graph
Junio C Hamano597ffcf2007-09-17 17:33:154104of all objects, and verifies their internal consistency (in addition
4105to just verifying their superficial consistency through the hash).
Junio C Hamano8f62db92007-02-01 00:22:224106
Junio C Hamano75485c82007-05-19 04:20:334107[[birdview-on-the-source-code]]
4108A birds-eye view of Git's source code
4109-------------------------------------
4110
4111It is not always easy for new developers to find their way through Git's
4112source code. This section gives you a little guidance to show where to
4113start.
4114
4115A good place to start is with the contents of the initial commit, with:
4116
4117----------------------------------------------------
4118$ git checkout e83c5163
4119----------------------------------------------------
4120
4121The initial revision lays the foundation for almost everything git has
4122today, but is small enough to read in one sitting.
4123
4124Note that terminology has changed since that revision. For example, the
4125README in that revision uses the word "changeset" to describe what we
4126now call a <<def_commit_object,commit>>.
4127
Junio C Hamanod32738e2008-07-09 19:53:424128Also, we do not call it "cache" any more, but rather "index"; however, the
Junio C Hamano75485c82007-05-19 04:20:334129file is still called `cache.h`. Remark: Not much reason to change it now,
4130especially since there is no good single name for it anyway, because it is
4131basically _the_ header file which is included by _all_ of Git's C sources.
4132
4133If you grasp the ideas in that initial commit, you should check out a
4134more recent version and skim `cache.h`, `object.h` and `commit.h`.
4135
4136In the early days, Git (in the tradition of UNIX) was a bunch of programs
4137which were extremely simple, and which you used in scripts, piping the
4138output of one into another. This turned out to be good for initial
4139development, since it was easier to test new things. However, recently
4140many of these parts have become builtins, and some of the core has been
4141"libified", i.e. put into libgit.a for performance, portability reasons,
4142and to avoid code duplication.
4143
4144By now, you know what the index is (and find the corresponding data
4145structures in `cache.h`), and that there are just a couple of object types
4146(blobs, trees, commits and tags) which inherit their common structure from
4147`struct object`, which is their first member (and thus, you can cast e.g.
4148`(struct object *)commit` to achieve the _same_ as `&commit->object`, i.e.
4149get at the object name and flags).
4150
4151Now is a good point to take a break to let this information sink in.
4152
4153Next step: get familiar with the object naming. Read <<naming-commits>>.
4154There are quite a few ways to name an object (and not only revisions!).
4155All of these are handled in `sha1_name.c`. Just have a quick look at
4156the function `get_sha1()`. A lot of the special handling is done by
4157functions like `get_sha1_basic()` or the likes.
4158
4159This is just to get you into the groove for the most libified part of Git:
4160the revision walker.
4161
Junio C Hamano5f9a6f02009-04-06 08:26:564162Basically, the initial version of `git log` was a shell script:
Junio C Hamano75485c82007-05-19 04:20:334163
4164----------------------------------------------------------------
4165$ git-rev-list --pretty $(git-rev-parse --default HEAD "$@") | \
4166LESS=-S ${PAGER:-less}
4167----------------------------------------------------------------
4168
4169What does this mean?
4170
Junio C Hamano5f9a6f02009-04-06 08:26:564171`git rev-list` is the original version of the revision walker, which
Junio C Hamano75485c82007-05-19 04:20:334172_always_ printed a list of revisions to stdout. It is still functional,
Junio C Hamano27a128b2009-08-13 01:23:004173and needs to, since most new Git commands start out as scripts using
Junio C Hamano5f9a6f02009-04-06 08:26:564174`git rev-list`.
Junio C Hamano75485c82007-05-19 04:20:334175
Junio C Hamano5f9a6f02009-04-06 08:26:564176`git rev-parse` is not as important any more; it was only used to filter out
Junio C Hamano75485c82007-05-19 04:20:334177options that were relevant for the different plumbing commands that were
4178called by the script.
4179
Junio C Hamano5f9a6f02009-04-06 08:26:564180Most of what `git rev-list` did is contained in `revision.c` and
Junio C Hamano75485c82007-05-19 04:20:334181`revision.h`. It wraps the options in a struct named `rev_info`, which
4182controls how and what revisions are walked, and more.
4183
Junio C Hamano5f9a6f02009-04-06 08:26:564184The original job of `git rev-parse` is now taken by the function
Junio C Hamano75485c82007-05-19 04:20:334185`setup_revisions()`, which parses the revisions and the common command line
4186options for the revision walker. This information is stored in the struct
4187`rev_info` for later consumption. You can do your own command line option
4188parsing after calling `setup_revisions()`. After that, you have to call
4189`prepare_revision_walk()` for initialization, and then you can get the
4190commits one by one with the function `get_revision()`.
4191
4192If you are interested in more details of the revision walking process,
4193just have a look at the first implementation of `cmd_log()`; call
Junio C Hamanofce7c7e2008-07-02 03:06:384194`git show v1.3.0{tilde}155^2{tilde}4` and scroll down to that function (note that you
Junio C Hamano75485c82007-05-19 04:20:334195no longer need to call `setup_pager()` directly).
4196
Junio C Hamano5f9a6f02009-04-06 08:26:564197Nowadays, `git log` is a builtin, which means that it is _contained_ in the
Junio C Hamano75485c82007-05-19 04:20:334198command `git`. The source side of a builtin is
4199
4200- a function called `cmd_<bla>`, typically defined in `builtin-<bla>.c`,
4201 and declared in `builtin.h`,
4202
4203- an entry in the `commands[]` array in `git.c`, and
4204
4205- an entry in `BUILTIN_OBJECTS` in the `Makefile`.
4206
4207Sometimes, more than one builtin is contained in one source file. For
4208example, `cmd_whatchanged()` and `cmd_log()` both reside in `builtin-log.c`,
4209since they share quite a bit of code. In that case, the commands which are
4210_not_ named like the `.c` file in which they live have to be listed in
4211`BUILT_INS` in the `Makefile`.
4212
Junio C Hamano5f9a6f02009-04-06 08:26:564213`git log` looks more complicated in C than it does in the original script,
Junio C Hamano75485c82007-05-19 04:20:334214but that allows for a much greater flexibility and performance.
4215
4216Here again it is a good point to take a pause.
4217
4218Lesson three is: study the code. Really, it is the best way to learn about
4219the organization of Git (after you know the basic concepts).
4220
4221So, think about something which you are interested in, say, "how can I
4222access a blob just knowing the object name of it?". The first step is to
4223find a Git command with which you can do it. In this example, it is either
Junio C Hamano5f9a6f02009-04-06 08:26:564224`git show` or `git cat-file`.
Junio C Hamano75485c82007-05-19 04:20:334225
Junio C Hamano5f9a6f02009-04-06 08:26:564226For the sake of clarity, let's stay with `git cat-file`, because it
Junio C Hamano75485c82007-05-19 04:20:334227
4228- is plumbing, and
4229
4230- was around even in the initial commit (it literally went only through
4231 some 20 revisions as `cat-file.c`, was renamed to `builtin-cat-file.c`
4232 when made a builtin, and then saw less than 10 versions).
4233
4234So, look into `builtin-cat-file.c`, search for `cmd_cat_file()` and look what
4235it does.
4236
4237------------------------------------------------------------------
4238 git_config(git_default_config);
4239 if (argc != 3)
Junio C Hamano5f9a6f02009-04-06 08:26:564240usage("git cat-file [-t|-s|-e|-p|<type>] <sha1>");
Junio C Hamano75485c82007-05-19 04:20:334241 if (get_sha1(argv[2], sha1))
4242 die("Not a valid object name %s", argv[2]);
4243------------------------------------------------------------------
4244
4245Let's skip over the obvious details; the only really interesting part
4246here is the call to `get_sha1()`. It tries to interpret `argv[2]` as an
4247object name, and if it refers to an object which is present in the current
4248repository, it writes the resulting SHA-1 into the variable `sha1`.
4249
4250Two things are interesting here:
4251
4252- `get_sha1()` returns 0 on _success_. This might surprise some new
4253 Git hackers, but there is a long tradition in UNIX to return different
Junio C Hamano764a6672007-10-23 01:23:314254 negative numbers in case of different errors--and 0 on success.
Junio C Hamano75485c82007-05-19 04:20:334255
4256- the variable `sha1` in the function signature of `get_sha1()` is `unsigned
Junio C Hamano2db3e752010-09-03 21:33:064257 char {asterisk}`, but is actually expected to be a pointer to `unsigned
Junio C Hamano75485c82007-05-19 04:20:334258 char[20]`. This variable will contain the 160-bit SHA-1 of the given
Junio C Hamano2db3e752010-09-03 21:33:064259 commit. Note that whenever a SHA-1 is passed as `unsigned char {asterisk}`, it
Junio C Hamano75485c82007-05-19 04:20:334260 is the binary representation, as opposed to the ASCII representation in
4261 hex characters, which is passed as `char *`.
4262
4263You will see both of these things throughout the code.
4264
4265Now, for the meat:
4266
4267-----------------------------------------------------------------------------
4268 case 0:
4269 buf = read_object_with_reference(sha1, argv[1], &size, NULL);
4270-----------------------------------------------------------------------------
4271
4272This is how you read a blob (actually, not only a blob, but any type of
4273object). To know how the function `read_object_with_reference()` actually
4274works, find the source code for it (something like `git grep
4275read_object_with | grep ":[a-z]"` in the git repository), and read
4276the source.
4277
4278To find out how the result can be used, just read on in `cmd_cat_file()`:
4279
4280-----------------------------------
4281 write_or_die(1, buf, size);
4282-----------------------------------
4283
4284Sometimes, you do not know where to look for a feature. In many such cases,
Junio C Hamano5f9a6f02009-04-06 08:26:564285it helps to search through the output of `git log`, and then `git show` the
Junio C Hamano75485c82007-05-19 04:20:334286corresponding commit.
4287
Junio C Hamano5f9a6f02009-04-06 08:26:564288Example: If you know that there was some test case for `git bundle`, but
Junio C Hamano75485c82007-05-19 04:20:334289do not remember where it was (yes, you _could_ `git grep bundle t/`, but that
4290does not illustrate the point!):
4291
4292------------------------
4293$ git log --no-merges t/
4294------------------------
4295
4296In the pager (`less`), just search for "bundle", go a few lines back,
4297and see that it is in commit 18449ab0... Now just copy this object name,
4298and paste it into the command line
4299
4300-------------------
4301$ git show 18449ab0
4302-------------------
4303
4304Voila.
4305
4306Another example: Find out what to do in order to make some script a
4307builtin:
4308
4309-------------------------------------------------
4310$ git log --no-merges --diff-filter=A builtin-*.c
4311-------------------------------------------------
4312
4313You see, Git is actually the best tool to find out about the source of Git
4314itself!
4315
Junio C Hamano3d30fd52007-05-08 00:32:534316[[glossary]]
Junio C Hamanobf984de2009-11-23 06:11:194317Git Glossary
Junio C Hamano9e1793f2008-06-02 07:31:164318============
4319
4320include::glossary-content.txt[]
Junio C Hamano8f62db92007-02-01 00:22:224321
Junio C Hamano75485c82007-05-19 04:20:334322[[git-quick-start]]
Junio C Hamanof614c642007-06-11 01:21:544323Appendix A: Git Quick Reference
4324===============================
Junio C Hamano75485c82007-05-19 04:20:334325
Junio C Hamanof614c642007-06-11 01:21:544326This is a quick summary of the major commands; the previous chapters
4327explain how these work in more detail.
Junio C Hamano75485c82007-05-19 04:20:334328
4329[[quick-creating-a-new-repository]]
4330Creating a new repository
4331-------------------------
4332
4333From a tarball:
4334
4335-----------------------------------------------
4336$ tar xzf project.tar.gz
4337$ cd project
4338$ git init
4339Initialized empty Git repository in .git/
4340$ git add .
4341$ git commit
4342-----------------------------------------------
4343
4344From a remote repository:
4345
4346-----------------------------------------------
4347$ git clone git://example.com/pub/project.git
4348$ cd project
4349-----------------------------------------------
4350
4351[[managing-branches]]
4352Managing branches
4353-----------------
4354
4355-----------------------------------------------
4356$ git branch # list all local branches in this repo
4357$ git checkout test # switch working directory to branch "test"
4358$ git branch new # create branch "new" starting at current HEAD
4359$ git branch -d new # delete branch "new"
4360-----------------------------------------------
4361
Junio C Hamano764a6672007-10-23 01:23:314362Instead of basing a new branch on current HEAD (the default), use:
Junio C Hamano75485c82007-05-19 04:20:334363
4364-----------------------------------------------
4365$ git branch new test # branch named "test"
4366$ git branch new v2.6.15 # tag named v2.6.15
4367$ git branch new HEAD^ # commit before the most recent
4368$ git branch new HEAD^^ # commit before that
4369$ git branch new test~10 # ten commits before tip of branch "test"
4370-----------------------------------------------
4371
4372Create and switch to a new branch at the same time:
4373
4374-----------------------------------------------
4375$ git checkout -b new v2.6.15
4376-----------------------------------------------
4377
4378Update and examine branches from the repository you cloned from:
4379
4380-----------------------------------------------
4381$ git fetch # update
4382$ git branch -r # list
4383 origin/master
4384 origin/next
4385 ...
4386$ git checkout -b masterwork origin/master
4387-----------------------------------------------
4388
4389Fetch a branch from a different repository, and give it a new
4390name in your repository:
4391
4392-----------------------------------------------
4393$ git fetch git://example.com/project.git theirbranch:mybranch
4394$ git fetch git://example.com/project.git v2.6.15:mybranch
4395-----------------------------------------------
4396
4397Keep a list of repositories you work with regularly:
4398
4399-----------------------------------------------
4400$ git remote add example git://example.com/project.git
4401$ git remote # list remote repositories
4402example
4403origin
4404$ git remote show example # get details
4405* remote example
4406 URL: git://example.com/project.git
4407 Tracked remote branches
Junio C Hamanoedc174c2008-10-23 05:18:544408 master
4409 next
4410 ...
Junio C Hamano75485c82007-05-19 04:20:334411$ git fetch example # update branches from example
4412$ git branch -r # list all remote branches
4413-----------------------------------------------
4414
4415
4416[[exploring-history]]
4417Exploring history
4418-----------------
4419
4420-----------------------------------------------
4421$ gitk # visualize and browse history
4422$ git log # list all commits
4423$ git log src/ # ...modifying src/
4424$ git log v2.6.15..v2.6.16 # ...in v2.6.16, not in v2.6.15
4425$ git log master..test # ...in branch test, not in branch master
4426$ git log test..master # ...in branch master, but not in test
4427$ git log test...master # ...in one branch, not in both
4428$ git log -S'foo()' # ...where difference contain "foo()"
4429$ git log --since="2 weeks ago"
4430$ git log -p # show patches as well
4431$ git show # most recent commit
4432$ git diff v2.6.15..v2.6.16 # diff between two tagged versions
4433$ git diff v2.6.15..HEAD # diff with current head
4434$ git grep "foo()" # search working directory for "foo()"
4435$ git grep v2.6.15 "foo()" # search old tree for "foo()"
4436$ git show v2.6.15:a.txt # look at old version of a.txt
4437-----------------------------------------------
4438
4439Search for regressions:
4440
4441-----------------------------------------------
4442$ git bisect start
4443$ git bisect bad # current version is bad
4444$ git bisect good v2.6.13-rc2 # last known good revision
4445Bisecting: 675 revisions left to test after this
4446# test here, then:
4447$ git bisect good # if this revision is good, or
4448$ git bisect bad # if this revision is bad.
4449# repeat until done.
4450-----------------------------------------------
4451
4452[[making-changes]]
4453Making changes
4454--------------
4455
4456Make sure git knows who to blame:
4457
4458------------------------------------------------
4459$ cat >>~/.gitconfig <<\EOF
4460[user]
4461name = Your Name Comes Here
4462email = you@yourdomain.example.com
4463EOF
4464------------------------------------------------
4465
4466Select file contents to include in the next commit, then make the
4467commit:
4468
4469-----------------------------------------------
4470$ git add a.txt # updated file
4471$ git add b.txt # new file
4472$ git rm c.txt # old file
4473$ git commit
4474-----------------------------------------------
4475
4476Or, prepare and create the commit in one step:
4477
4478-----------------------------------------------
4479$ git commit d.txt # use latest content only of d.txt
4480$ git commit -a # use latest content of all tracked files
4481-----------------------------------------------
4482
4483[[merging]]
4484Merging
4485-------
4486
4487-----------------------------------------------
4488$ git merge test # merge branch "test" into the current branch
4489$ git pull git://example.com/project.git master
4490 # fetch and merge in remote branch
4491$ git pull . test # equivalent to git merge test
4492-----------------------------------------------
4493
4494[[sharing-your-changes]]
4495Sharing your changes
4496--------------------
4497
4498Importing or exporting patches:
4499
4500-----------------------------------------------
4501$ git format-patch origin..HEAD # format a patch for each commit
4502# in HEAD but not in origin
4503$ git am mbox # import patches from the mailbox "mbox"
4504-----------------------------------------------
4505
4506Fetch a branch in a different git repository, then merge into the
4507current branch:
4508
4509-----------------------------------------------
4510$ git pull git://example.com/project.git theirbranch
4511-----------------------------------------------
4512
4513Store the fetched branch into a local branch before merging into the
4514current branch:
4515
4516-----------------------------------------------
4517$ git pull git://example.com/project.git theirbranch:mybranch
4518-----------------------------------------------
4519
4520After creating commits on a local branch, update the remote
4521branch with your commits:
4522
4523-----------------------------------------------
4524$ git push ssh://example.com/project.git mybranch:theirbranch
4525-----------------------------------------------
4526
4527When remote and local branch are both named "test":
4528
4529-----------------------------------------------
4530$ git push ssh://example.com/project.git test
4531-----------------------------------------------
4532
4533Shortcut version for a frequently used remote repository:
4534
4535-----------------------------------------------
4536$ git remote add example ssh://example.com/project.git
4537$ git push example test
4538-----------------------------------------------
4539
4540[[repository-maintenance]]
4541Repository maintenance
4542----------------------
4543
4544Check for corruption:
4545
4546-----------------------------------------------
4547$ git fsck
4548-----------------------------------------------
4549
4550Recompress, remove unused cruft:
4551
4552-----------------------------------------------
4553$ git gc
4554-----------------------------------------------
4555
4556
Junio C Hamano3d30fd52007-05-08 00:32:534557[[todo]]
Junio C Hamano75485c82007-05-19 04:20:334558Appendix B: Notes and todo list for this manual
4559===============================================
Junio C Hamano8f62db92007-02-01 00:22:224560
4561This is a work in progress.
4562
4563The basic requirements:
Junio C Hamano597ffcf2007-09-17 17:33:154564
4565- It must be readable in order, from beginning to end, by someone
4566 intelligent with a basic grasp of the UNIX command line, but without
4567 any special knowledge of git. If necessary, any other prerequisites
4568 should be specifically mentioned as they arise.
4569- Whenever possible, section headings should clearly describe the task
4570 they explain how to do, in language that requires no more knowledge
4571 than necessary: for example, "importing patches into a project" rather
Junio C Hamano5f9a6f02009-04-06 08:26:564572 than "the `git am` command"
Junio C Hamano8f62db92007-02-01 00:22:224573
4574Think about how to create a clear chapter dependency graph that will
4575allow people to get to important topics without necessarily reading
4576everything in between.
4577
Junio C Hamano8f62db92007-02-01 00:22:224578Scan Documentation/ for other stuff left out; in particular:
Junio C Hamano597ffcf2007-09-17 17:33:154579
4580- howto's
4581- some of technical/?
4582- hooks
Junio C Hamano35738e82008-01-07 07:55:464583- list of commands in linkgit:git[1]
Junio C Hamano8f62db92007-02-01 00:22:224584
4585Scan email archives for other stuff left out
4586
4587Scan man pages to see if any assume more background than this manual
4588provides.
4589
4590Simplify beginning by suggesting disconnected head instead of
4591temporary branch creation?
4592
Junio C Hamano8f62db92007-02-01 00:22:224593Add more good examples. Entire sections of just cookbook examples
4594might be a good idea; maybe make an "advanced examples" section a
4595standard end-of-chapter section?
4596
4597Include cross-references to the glossary, where appropriate.
4598
4599Document shallow clones? See draft 1.5.0 release notes for some
4600documentation.
4601
Junio C Hamanoee1e4282007-02-04 08:32:044602Add a section on working with other version control systems, including
Junio C Hamano8f62db92007-02-01 00:22:224603CVS, Subversion, and just imports of series of release tarballs.
4604
4605More details on gitweb?
4606
4607Write a chapter on using plumbing and writing scripts.
Junio C Hamanof614c642007-06-11 01:21:544608
4609Alternates, clone -reference, etc.
4610
Junio C Hamanoce3650e2007-11-26 04:20:114611More on recovery from repository corruption. See:
4612http://marc.theaimsgroup.com/?l=git&m=117263864820799&w=2
4613http://marc.theaimsgroup.com/?l=git&m=117147855503798&w=2