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GITCVS-MIGRATION(7) Git Manual GITCVS-MIGRATION(7)
NAME
gitcvs-migration - Git for CVS users
SYNOPSIS
git cvsimport *
DESCRIPTION
Git differs from CVS in that every working tree contains a repository with a full copy of
the project history, and no repository is inherently more important than any other.
However, you can emulate the CVS model by designating a single shared repository which
people can synchronize with; this document explains how to do that.
Some basic familiarity with Git is required. Having gone through gittutorial(7) and
gitglossary(7) should be sufficient.
DEVELOPING AGAINST A SHARED REPOSITORY
Suppose a shared repository is set up in /pub/repo.git on the host foo.com. Then as an
individual committer you can clone the shared repository over ssh with:
$ git clone foo.com:/pub/repo.git/ my-project
$ cd my-project
and hack away. The equivalent of cvs update is
$ git pull origin
which merges in any work that others might have done since the clone operation. If there
are uncommitted changes in your working tree, commit them first before running git pull.
Note
The pull command knows where to get updates from because of certain configuration
variables that were set by the first git clone command; see git config -l and the git-
config(1) man page for details.
You can update the shared repository with your changes by first committing your changes,
and then using the git push command:
$ git push origin master
to "push" those commits to the shared repository. If someone else has updated the
repository more recently, git push, like cvs commit, will complain, in which case you must
pull any changes before attempting the push again.
In the git push command above we specify the name of the remote branch to update (master).
If we leave that out, git push tries to update any branches in the remote repository that
have the same name as a branch in the local repository. So the last push can be done with
either of:
$ git push origin
$ git push foo.com:/pub/project.git/
as long as the shared repository does not have any branches other than master.
SETTING UP A SHARED REPOSITORY
We assume you have already created a Git repository for your project, possibly created
from scratch or from a tarball (see gittutorial(7)), or imported from an already existing
CVS repository (see the next section).
Assume your existing repo is at /home/alice/myproject. Create a new "bare" repository (a
repository without a working tree) and fetch your project into it:
$ mkdir /pub/my-repo.git
$ cd /pub/my-repo.git
$ git --bare init --shared
$ git --bare fetch /home/alice/myproject master:master
Next, give every team member read/write access to this repository. One easy way to do this
is to give all the team members ssh access to the machine where the repository is hosted.
If you don’t want to give them a full shell on the machine, there is a restricted shell
which only allows users to do Git pushes and pulls; see git-shell(1).
Put all the committers in the same group, and make the repository writable by that group:
$ chgrp -R $group /pub/my-repo.git
Make sure committers have a umask of at most 027, so that the directories they create are
writable and searchable by other group members.
IMPORTING A CVS ARCHIVE
First, install version 2.1 or higher of cvsps from http://www.cobite.com/cvsps/ and make
sure it is in your path. Then cd to a checked out CVS working directory of the project you
are interested in and run git-cvsimport(1):
$ git cvsimport -C <destination> <module>
This puts a Git archive of the named CVS module in the directory <destination>, which will
be created if necessary.
The import checks out from CVS every revision of every file. Reportedly cvsimport can
average some twenty revisions per second, so for a medium-sized project this should not
take more than a couple of minutes. Larger projects or remote repositories may take
longer.
The main trunk is stored in the Git branch named origin, and additional CVS branches are
stored in Git branches with the same names. The most recent version of the main trunk is
also left checked out on the master branch, so you can start adding your own changes right
away.
The import is incremental, so if you call it again next month it will fetch any CVS
updates that have been made in the meantime. For this to work, you must not modify the
imported branches; instead, create new branches for your own changes, and merge in the
imported branches as necessary.
If you want a shared repository, you will need to make a bare clone of the imported
directory, as described above. Then treat the imported directory as another development
clone for purposes of merging incremental imports.
ADVANCED SHARED REPOSITORY MANAGEMENT
Git allows you to specify scripts called "hooks" to be run at certain points. You can use
these, for example, to send all commits to the shared repository to a mailing list. See
githooks(5).
You can enforce finer grained permissions using update hooks. See Controlling access to
branches using update hooks[1].
PROVIDING CVS ACCESS TO A GIT REPOSITORY
It is also possible to provide true CVS access to a Git repository, so that developers can
still use CVS; see git-cvsserver(1) for details.
ALTERNATIVE DEVELOPMENT MODELS
CVS users are accustomed to giving a group of developers commit access to a common
repository. As we’ve seen, this is also possible with Git. However, the distributed nature
of Git allows other development models, and you may want to first consider whether one of
them might be a better fit for your project.
For example, you can choose a single person to maintain the project’s primary public
repository. Other developers then clone this repository and each work in their own clone.
When they have a series of changes that they’re happy with, they ask the maintainer to
pull from the branch containing the changes. The maintainer reviews their changes and
pulls them into the primary repository, which other developers pull from as necessary to
stay coordinated. The Linux kernel and other projects use variants of this model.
With a small group, developers may just pull changes from each other’s repositories
without the need for a central maintainer.
SEE ALSO
gittutorial(7), gittutorial-2(7), gitcore-tutorial(7), gitglossary(7), Everyday Git[2],
The Git User’s Manual[3]
GIT
Part of the git(1) suite.
NOTES
1. Controlling access to branches using update hooks
file:///usr/share/doc/git/html/howto/update-hook-example.html
2. Everyday Git
file:///usr/share/doc/git/html/everyday.html
3. The Git User’s Manual
file:///usr/share/doc/git/html/user-manual.html
Git 2.1.4 05/28/2018 GITCVS-MIGRATION(7)
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