1gitcvs-migration(7) 2=================== 3 4NAME 5---- 6gitcvs-migration - Git for CVS users 7 8SYNOPSIS 9-------- 10[verse] 11'git cvsimport' * 12 13DESCRIPTION 14----------- 15 16Git differs from CVS in that every working tree contains a repository with 17a full copy of the project history, and no repository is inherently more 18important than any other. However, you can emulate the CVS model by 19designating a single shared repository which people can synchronize with; 20this document explains how to do that. 21 22Some basic familiarity with Git is required. Having gone through 23linkgit:gittutorial[7] and 24linkgit:gitglossary[7] should be sufficient. 25 26Developing against a shared repository 27-------------------------------------- 28 29Suppose a shared repository is set up in /pub/repo.git on the host 30foo.com. Then as an individual committer you can clone the shared 31repository over ssh with: 32 33------------------------------------------------ 34$ git clone foo.com:/pub/repo.git/ my-project 35$ cd my-project 36------------------------------------------------ 37 38and hack away. The equivalent of 'cvs update' is 39 40------------------------------------------------ 41$ git pull origin 42------------------------------------------------ 43 44which merges in any work that others might have done since the clone 45operation. If there are uncommitted changes in your working tree, commit 46them first before running git pull. 47 48[NOTE] 49================================ 50The 'pull' command knows where to get updates from because of certain 51configuration variables that were set by the first 'git clone' 52command; see `git config -l` and the linkgit:git-config[1] man 53page for details. 54================================ 55 56You can update the shared repository with your changes by first committing 57your changes, and then using the 'git push' command: 58 59------------------------------------------------ 60$ git push origin master 61------------------------------------------------ 62 63to "push" those commits to the shared repository. If someone else has 64updated the repository more recently, 'git push', like 'cvs commit', will 65complain, in which case you must pull any changes before attempting the 66push again. 67 68In the 'git push' command above we specify the name of the remote branch 69to update (`master`). If we leave that out, 'git push' tries to update 70any branches in the remote repository that have the same name as a branch 71in the local repository. So the last 'push' can be done with either of: 72 73------------ 74$ git push origin 75$ git push foo.com:/pub/project.git/ 76------------ 77 78as long as the shared repository does not have any branches 79other than `master`. 80 81Setting Up a Shared Repository 82------------------------------ 83 84We assume you have already created a Git repository for your project, 85possibly created from scratch or from a tarball (see 86linkgit:gittutorial[7]), or imported from an already existing CVS 87repository (see the next section). 88 89Assume your existing repo is at /home/alice/myproject. Create a new "bare" 90repository (a repository without a working tree) and fetch your project into 91it: 92 93------------------------------------------------ 94$ mkdir /pub/my-repo.git 95$ cd /pub/my-repo.git 96$ git --bare init --shared 97$ git --bare fetch /home/alice/myproject master:master 98------------------------------------------------ 99 100Next, give every team member read/write access to this repository. One 101easy way to do this is to give all the team members ssh access to the 102machine where the repository is hosted. If you don't want to give them a 103full shell on the machine, there is a restricted shell which only allows 104users to do Git pushes and pulls; see linkgit:git-shell[1]. 105 106Put all the committers in the same group, and make the repository 107writable by that group: 108 109------------------------------------------------ 110$ chgrp -R $group /pub/my-repo.git 111------------------------------------------------ 112 113Make sure committers have a umask of at most 027, so that the directories 114they create are writable and searchable by other group members. 115 116Importing a CVS archive 117----------------------- 118 119NOTE: These instructions use the `git-cvsimport` script which ships with 120git, but other importers may provide better results. See the note in 121linkgit:git-cvsimport[1] for other options. 122 123First, install version 2.1 or higher of cvsps from 124https://github.com/andreyvit/cvsps[https://github.com/andreyvit/cvsps] and make 125sure it is in your path. Then cd to a checked out CVS working directory 126of the project you are interested in and run linkgit:git-cvsimport[1]: 127 128------------------------------------------- 129$ git cvsimport -C <destination> <module> 130------------------------------------------- 131 132This puts a Git archive of the named CVS module in the directory 133<destination>, which will be created if necessary. 134 135The import checks out from CVS every revision of every file. Reportedly 136cvsimport can average some twenty revisions per second, so for a 137medium-sized project this should not take more than a couple of minutes. 138Larger projects or remote repositories may take longer. 139 140The main trunk is stored in the Git branch named `origin`, and additional 141CVS branches are stored in Git branches with the same names. The most 142recent version of the main trunk is also left checked out on the `master` 143branch, so you can start adding your own changes right away. 144 145The import is incremental, so if you call it again next month it will 146fetch any CVS updates that have been made in the meantime. For this to 147work, you must not modify the imported branches; instead, create new 148branches for your own changes, and merge in the imported branches as 149necessary. 150 151If you want a shared repository, you will need to make a bare clone 152of the imported directory, as described above. Then treat the imported 153directory as another development clone for purposes of merging 154incremental imports. 155 156Advanced Shared Repository Management 157------------------------------------- 158 159Git allows you to specify scripts called "hooks" to be run at certain 160points. You can use these, for example, to send all commits to the shared 161repository to a mailing list. See linkgit:githooks[5]. 162 163You can enforce finer grained permissions using update hooks. See 164link:howto/update-hook-example.html[Controlling access to branches using 165update hooks]. 166 167Providing CVS Access to a Git Repository 168---------------------------------------- 169 170It is also possible to provide true CVS access to a Git repository, so 171that developers can still use CVS; see linkgit:git-cvsserver[1] for 172details. 173 174Alternative Development Models 175------------------------------ 176 177CVS users are accustomed to giving a group of developers commit access to 178a common repository. As we've seen, this is also possible with Git. 179However, the distributed nature of Git allows other development models, 180and you may want to first consider whether one of them might be a better 181fit for your project. 182 183For example, you can choose a single person to maintain the project's 184primary public repository. Other developers then clone this repository 185and each work in their own clone. When they have a series of changes that 186they're happy with, they ask the maintainer to pull from the branch 187containing the changes. The maintainer reviews their changes and pulls 188them into the primary repository, which other developers pull from as 189necessary to stay coordinated. The Linux kernel and other projects use 190variants of this model. 191 192With a small group, developers may just pull changes from each other's 193repositories without the need for a central maintainer. 194 195SEE ALSO 196-------- 197linkgit:gittutorial[7], 198linkgit:gittutorial-2[7], 199linkgit:gitcore-tutorial[7], 200linkgit:gitglossary[7], 201linkgit:giteveryday[7], 202link:user-manual.html[The Git User's Manual] 203 204GIT 205--- 206Part of the linkgit:git[1] suite.