gitcvs-migration: Link to git-cvsimport documentation
[git/git.git] / Documentation / gitcvs-migration.txt
1 gitcvs-migration(7)
2 ===================
3
4 NAME
5 ----
6 gitcvs-migration - git for CVS users
7
8 SYNOPSIS
9 --------
10 git cvsimport *
11
12 DESCRIPTION
13 -----------
14
15 Git differs from CVS in that every working tree contains a repository with
16 a full copy of the project history, and no repository is inherently more
17 important than any other. However, you can emulate the CVS model by
18 designating a single shared repository which people can synchronize with;
19 this document explains how to do that.
20
21 Some basic familiarity with git is required. Having gone through
22 linkgit:gittutorial[7] and
23 linkgit:gitglossary[7] should be sufficient.
24
25 Developing against a shared repository
26 --------------------------------------
27
28 Suppose a shared repository is set up in /pub/repo.git on the host
29 foo.com. Then as an individual committer you can clone the shared
30 repository over ssh with:
31
32 ------------------------------------------------
33 $ git clone foo.com:/pub/repo.git/ my-project
34 $ cd my-project
35 ------------------------------------------------
36
37 and hack away. The equivalent of 'cvs update' is
38
39 ------------------------------------------------
40 $ git pull origin
41 ------------------------------------------------
42
43 which merges in any work that others might have done since the clone
44 operation. If there are uncommitted changes in your working tree, commit
45 them first before running git pull.
46
47 [NOTE]
48 ================================
49 The 'pull' command knows where to get updates from because of certain
50 configuration variables that were set by the first 'git-clone'
51 command; see `git config -l` and the linkgit:git-config[1] man
52 page for details.
53 ================================
54
55 You can update the shared repository with your changes by first committing
56 your changes, and then using the 'git-push' command:
57
58 ------------------------------------------------
59 $ git push origin master
60 ------------------------------------------------
61
62 to "push" those commits to the shared repository. If someone else has
63 updated the repository more recently, 'git-push', like 'cvs commit', will
64 complain, in which case you must pull any changes before attempting the
65 push again.
66
67 In the 'git-push' command above we specify the name of the remote branch
68 to update (`master`). If we leave that out, 'git-push' tries to update
69 any branches in the remote repository that have the same name as a branch
70 in the local repository. So the last 'push' can be done with either of:
71
72 ------------
73 $ git push origin
74 $ git push foo.com:/pub/project.git/
75 ------------
76
77 as long as the shared repository does not have any branches
78 other than `master`.
79
80 Setting Up a Shared Repository
81 ------------------------------
82
83 We assume you have already created a git repository for your project,
84 possibly created from scratch or from a tarball (see
85 linkgit:gittutorial[7]), or imported from an already existing CVS
86 repository (see the next section).
87
88 Assume your existing repo is at /home/alice/myproject. Create a new "bare"
89 repository (a repository without a working tree) and fetch your project into
90 it:
91
92 ------------------------------------------------
93 $ mkdir /pub/my-repo.git
94 $ cd /pub/my-repo.git
95 $ git --bare init --shared
96 $ git --bare fetch /home/alice/myproject master:master
97 ------------------------------------------------
98
99 Next, give every team member read/write access to this repository. One
100 easy way to do this is to give all the team members ssh access to the
101 machine where the repository is hosted. If you don't want to give them a
102 full shell on the machine, there is a restricted shell which only allows
103 users to do git pushes and pulls; see linkgit:git-shell[1].
104
105 Put all the committers in the same group, and make the repository
106 writable by that group:
107
108 ------------------------------------------------
109 $ chgrp -R $group /pub/my-repo.git
110 ------------------------------------------------
111
112 Make sure committers have a umask of at most 027, so that the directories
113 they create are writable and searchable by other group members.
114
115 Importing a CVS archive
116 -----------------------
117
118 First, install version 2.1 or higher of cvsps from
119 link:http://www.cobite.com/cvsps/[http://www.cobite.com/cvsps/] and make
120 sure it is in your path. Then cd to a checked out CVS working directory
121 of the project you are interested in and run linkgit:git-cvsimport[1]:
122
123 -------------------------------------------
124 $ git cvsimport -C <destination> <module>
125 -------------------------------------------
126
127 This puts a git archive of the named CVS module in the directory
128 <destination>, which will be created if necessary.
129
130 The import checks out from CVS every revision of every file. Reportedly
131 cvsimport can average some twenty revisions per second, so for a
132 medium-sized project this should not take more than a couple of minutes.
133 Larger projects or remote repositories may take longer.
134
135 The main trunk is stored in the git branch named `origin`, and additional
136 CVS branches are stored in git branches with the same names. The most
137 recent version of the main trunk is also left checked out on the `master`
138 branch, so you can start adding your own changes right away.
139
140 The import is incremental, so if you call it again next month it will
141 fetch any CVS updates that have been made in the meantime. For this to
142 work, you must not modify the imported branches; instead, create new
143 branches for your own changes, and merge in the imported branches as
144 necessary.
145
146 If you want a shared repository, you will need to make a bare clone
147 of the imported directory, as described above. Then treat the imported
148 directory as another development clone for purposes of merging
149 incremental imports.
150
151 Advanced Shared Repository Management
152 -------------------------------------
153
154 Git allows you to specify scripts called "hooks" to be run at certain
155 points. You can use these, for example, to send all commits to the shared
156 repository to a mailing list. See linkgit:githooks[5].
157
158 You can enforce finer grained permissions using update hooks. See
159 link:howto/update-hook-example.txt[Controlling access to branches using
160 update hooks].
161
162 Providing CVS Access to a git Repository
163 ----------------------------------------
164
165 It is also possible to provide true CVS access to a git repository, so
166 that developers can still use CVS; see linkgit:git-cvsserver[1] for
167 details.
168
169 Alternative Development Models
170 ------------------------------
171
172 CVS users are accustomed to giving a group of developers commit access to
173 a common repository. As we've seen, this is also possible with git.
174 However, the distributed nature of git allows other development models,
175 and you may want to first consider whether one of them might be a better
176 fit for your project.
177
178 For example, you can choose a single person to maintain the project's
179 primary public repository. Other developers then clone this repository
180 and each work in their own clone. When they have a series of changes that
181 they're happy with, they ask the maintainer to pull from the branch
182 containing the changes. The maintainer reviews their changes and pulls
183 them into the primary repository, which other developers pull from as
184 necessary to stay coordinated. The Linux kernel and other projects use
185 variants of this model.
186
187 With a small group, developers may just pull changes from each other's
188 repositories without the need for a central maintainer.
189
190 SEE ALSO
191 --------
192 linkgit:gittutorial[7],
193 linkgit:gittutorial-2[7],
194 linkgit:gitcore-tutorial[7],
195 linkgit:gitglossary[7],
196 link:everyday.html[Everyday Git],
197 link:user-manual.html[The Git User's Manual]
198
199 GIT
200 ---
201 Part of the linkgit:git[1] suite.