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.\"     Title: gitcvs-migration
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.75.2 <http://docbook.sf.net/>
.\"      Date: 07/23/2011
.\"    Manual: Git Manual
.\"    Source: Git 1.7.6.345.g5c2f8
.\"  Language: English
.\"
.TH "GITCVS\-MIGRATION" "7" "07/23/2011" "Git 1\&.7\&.6\&.345\&.g5c2f8" "Git Manual"
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.SH "NAME"
gitcvs-migration \- git for CVS users
.SH "SYNOPSIS"
.sp
.nf
\fIgit cvsimport\fR *
.fi
.sp
.SH "DESCRIPTION"
.sp
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\&.
.sp
Some basic familiarity with git is required\&. Having gone through \fBgittutorial\fR(7) and \fBgitglossary\fR(7) should be sufficient\&.
.SH "DEVELOPING AGAINST A SHARED REPOSITORY"
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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:
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.if n \{\
.RS 4
.\}
.nf
$ git clone foo\&.com:/pub/repo\&.git/ my\-project
$ cd my\-project
.fi
.if n \{\
.RE
.\}
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.sp
and hack away\&. The equivalent of \fIcvs update\fR is
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.if n \{\
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$ git pull origin
.fi
.if n \{\
.RE
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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\&.
.if n \{\
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.\}
.RS 4
.it 1 an-trap
.nr an-no-space-flag 1
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\fBNote\fR
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The \fIpull\fR command knows where to get updates from because of certain configuration variables that were set by the first \fIgit clone\fR command; see git config \-l and the \fBgit-config\fR(1) man page for details\&.
.sp .5v
.RE
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You can update the shared repository with your changes by first committing your changes, and then using the \fIgit push\fR command:
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.if n \{\
.RS 4
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$ git push origin master
.fi
.if n \{\
.RE
.\}
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to "push" those commits to the shared repository\&. If someone else has updated the repository more recently, \fIgit push\fR, like \fIcvs commit\fR, will complain, in which case you must pull any changes before attempting the push again\&.
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In the \fIgit push\fR command above we specify the name of the remote branch to update (master)\&. If we leave that out, \fIgit push\fR tries to update any branches in the remote repository that have the same name as a branch in the local repository\&. So the last \fIpush\fR can be done with either of:
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.if n \{\
.RS 4
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$ git push origin
$ git push foo\&.com:/pub/project\&.git/
.fi
.if n \{\
.RE
.\}
.sp
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as long as the shared repository does not have any branches other than master\&.
.SH "SETTING UP A SHARED REPOSITORY"
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We assume you have already created a git repository for your project, possibly created from scratch or from a tarball (see \fBgittutorial\fR(7)), or imported from an already existing CVS repository (see the next section)\&.
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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:
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.if n \{\
.RS 4
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$ mkdir /pub/my\-repo\&.git
$ cd /pub/my\-repo\&.git
$ git \-\-bare init \-\-shared
$ git \-\-bare fetch /home/alice/myproject master:master
.fi
.if n \{\
.RE
.\}
.sp
.sp
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\(cqt 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 \fBgit-shell\fR(1)\&.
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Put all the committers in the same group, and make the repository writable by that group:
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.if n \{\
.RS 4
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$ chgrp \-R $group /pub/my\-repo\&.git
.fi
.if n \{\
.RE
.\}
.sp
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Make sure committers have a umask of at most 027, so that the directories they create are writable and searchable by other group members\&.
.SH "IMPORTING A CVS ARCHIVE"
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First, install version 2\&.1 or higher of cvsps from \m[blue]\fBhttp://www\&.cobite\&.com/cvsps/\fR\m[] and make sure it is in your path\&. Then cd to a checked out CVS working directory of the project you are interested in and run \fBgit-cvsimport\fR(1):
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$ git cvsimport \-C <destination> <module>
.fi
.if n \{\
.RE
.\}
.sp
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This puts a git archive of the named CVS module in the directory <destination>, which will be created if necessary\&.
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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\&.
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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\&.
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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\&.
.sp
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\&.
.SH "ADVANCED SHARED REPOSITORY MANAGEMENT"
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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 \fBgithooks\fR(5)\&.
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You can enforce finer grained permissions using update hooks\&. See \m[blue]\fBControlling access to branches using update hooks\fR\m[]\&\s-2\u[1]\d\s+2\&.
.SH "PROVIDING CVS ACCESS TO A GIT REPOSITORY"
.sp
It is also possible to provide true CVS access to a git repository, so that developers can still use CVS; see \fBgit-cvsserver\fR(1) for details\&.
.SH "ALTERNATIVE DEVELOPMENT MODELS"
.sp
CVS users are accustomed to giving a group of developers commit access to a common repository\&. As we\(cqve 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\&.
.sp
For example, you can choose a single person to maintain the project\(cqs 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\(cqre 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\&.
.sp
With a small group, developers may just pull changes from each other\(cqs repositories without the need for a central maintainer\&.
.SH "SEE ALSO"
.sp
\fBgittutorial\fR(7), \fBgittutorial-2\fR(7), \fBgitcore-tutorial\fR(7), \fBgitglossary\fR(7), \m[blue]\fBEveryday Git\fR\m[]\&\s-2\u[2]\d\s+2, \m[blue]\fBThe Git User\(cqs Manual\fR\m[]\&\s-2\u[3]\d\s+2
.SH "GIT"
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Part of the \fBgit\fR(1) suite\&.
.SH "NOTES"
.IP " 1." 4
Controlling access to branches using update hooks
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\%http://www.kernel.org/pub/software/scm/git/docs/howto/update-hook-example.txt
.RE
.IP " 2." 4
Everyday Git
.RS 4
\%http://www.kernel.org/pub/software/scm/git/docs/everyday.html
.RE
.IP " 3." 4
The Git User\(cqs Manual
.RS 4
\%http://www.kernel.org/pub/software/scm/git/docs/user-manual.html
.RE