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