mirror of
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e0d10e1c63
Signed-off-by: Tom Prince <tom.prince@ualberta.net> Signed-off-by: Junio C Hamano <junkio@cox.net>
171 lines
6.8 KiB
Text
171 lines
6.8 KiB
Text
git for CVS users
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=================
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Git differs from CVS in that every working tree contains a repository with
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a full copy of the project history, and no repository is inherently more
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important than any other. However, you can emulate the CVS model by
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designating a single shared repository which people can synchronize with;
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this document explains how to do that.
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Some basic familiarity with git is required. This
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link:tutorial.html[tutorial introduction to git] should be sufficient.
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Developing against a shared repository
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--------------------------------------
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Suppose a shared repository is set up in /pub/repo.git on the host
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foo.com. Then as an individual committer you can clone the shared
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repository over ssh with:
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------------------------------------------------
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$ git clone foo.com:/pub/repo.git/ my-project
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$ cd my-project
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------------------------------------------------
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and hack away. The equivalent of `cvs update` is
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------------------------------------------------
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$ git pull origin
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------------------------------------------------
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which merges in any work that others might have done since the clone
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operation. If there are uncommitted changes in your working tree, commit
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them first before running git pull.
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[NOTE]
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================================
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The `pull` command knows where to get updates from because of certain
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configuration variables that were set by the first `git clone`
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command; see `git config -l` and the gitlink:git-config[1] man
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page for details.
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================================
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You can update the shared repository with your changes by first committing
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your changes, and then using the gitlink:git-push[1] command:
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------------------------------------------------
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$ git push origin master
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------------------------------------------------
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to "push" those commits to the shared repository. If someone else has
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updated the repository more recently, `git push`, like `cvs commit`, will
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complain, in which case you must pull any changes before attempting the
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push again.
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In the `git push` command above we specify the name of the remote branch
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to update (`master`). If we leave that out, `git push` tries to update
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any branches in the remote repository that have the same name as a branch
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in the local repository. So the last `push` can be done with either of:
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------------
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$ git push origin
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$ git push foo.com:/pub/project.git/
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------------
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as long as the shared repository does not have any branches
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other than `master`.
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Setting Up a Shared Repository
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------------------------------
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We assume you have already created a git repository for your project,
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possibly created from scratch or from a tarball (see the
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link:tutorial.html[tutorial]), or imported from an already existing CVS
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repository (see the next section).
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Assume your existing repo is at /home/alice/myproject. Create a new "bare"
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repository (a repository without a working tree) and fetch your project into
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it:
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------------------------------------------------
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$ mkdir /pub/my-repo.git
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$ cd /pub/my-repo.git
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$ git --bare init --shared
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$ git --bare fetch /home/alice/myproject master:master
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------------------------------------------------
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Next, give every team member read/write access to this repository. One
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easy way to do this is to give all the team members ssh access to the
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machine where the repository is hosted. If you don't want to give them a
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full shell on the machine, there is a restricted shell which only allows
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users to do git pushes and pulls; see gitlink:git-shell[1].
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Put all the committers in the same group, and make the repository
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writable by that group:
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------------------------------------------------
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$ chgrp -R $group /pub/my-repo.git
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------------------------------------------------
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Make sure committers have a umask of at most 027, so that the directories
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they create are writable and searchable by other group members.
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Importing a CVS archive
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-----------------------
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First, install version 2.1 or higher of cvsps from
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link:http://www.cobite.com/cvsps/[http://www.cobite.com/cvsps/] and make
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sure it is in your path. Then cd to a checked out CVS working directory
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of the project you are interested in and run gitlink:git-cvsimport[1]:
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-------------------------------------------
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$ git cvsimport -C <destination>
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-------------------------------------------
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This puts a git archive of the named CVS module in the directory
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<destination>, which will be created if necessary.
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The import checks out from CVS every revision of every file. Reportedly
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cvsimport can average some twenty revisions per second, so for a
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medium-sized project this should not take more than a couple of minutes.
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Larger projects or remote repositories may take longer.
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The main trunk is stored in the git branch named `origin`, and additional
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CVS branches are stored in git branches with the same names. The most
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recent version of the main trunk is also left checked out on the `master`
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branch, so you can start adding your own changes right away.
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The import is incremental, so if you call it again next month it will
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fetch any CVS updates that have been made in the meantime. For this to
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work, you must not modify the imported branches; instead, create new
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branches for your own changes, and merge in the imported branches as
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necessary.
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Advanced Shared Repository Management
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-------------------------------------
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Git allows you to specify scripts called "hooks" to be run at certain
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points. You can use these, for example, to send all commits to the shared
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repository to a mailing list. See link:hooks.html[Hooks used by git].
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You can enforce finer grained permissions using update hooks. See
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link:howto/update-hook-example.txt[Controlling access to branches using
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update hooks].
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Providing CVS Access to a git Repository
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----------------------------------------
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It is also possible to provide true CVS access to a git repository, so
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that developers can still use CVS; see gitlink:git-cvsserver[1] for
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details.
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Alternative Development Models
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------------------------------
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CVS users are accustomed to giving a group of developers commit access to
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a common repository. As we've seen, this is also possible with git.
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However, the distributed nature of git allows other development models,
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and you may want to first consider whether one of them might be a better
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fit for your project.
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For example, you can choose a single person to maintain the project's
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primary public repository. Other developers then clone this repository
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and each work in their own clone. When they have a series of changes that
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they're happy with, they ask the maintainer to pull from the branch
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containing the changes. The maintainer reviews their changes and pulls
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them into the primary repository, which other developers pull from as
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necessary to stay coordinated. The Linux kernel and other projects use
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variants of this model.
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With a small group, developers may just pull changes from each other's
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repositories without the need for a central maintainer.
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