Tribblix: manual page: gitcvs-migration.7

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

Note

These instructions use the git-cvsimport script which ships with
git, but other importers may provide better results. See the note
in git-cvsimport(1) for other options.

First, install version 2.1 or higher of cvsps from
https://github.com/andreyvit/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.

GIT

Part of the git(1) suite

NOTES

1. Controlling access to branches using update hooks
git-htmldocs/howto/update-hook-example.html

2. The Git User's Manual
git-htmldocs/user-manual.html

Git 2.48.1 2025-01-13 GITCVS-MIGRATION(7)