cvs2bzr.html

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<h1>cvs2bzr</h1>

<h2>Index</h2>

<ul>

  <li><a href="#intro">Introduction</a></li>

  <li><a href="#reqs">Requirements</a></li>

  <li><a href="#status">Development status</a></li>

  <li><a href="#docs">Documentation</a></li>

  <li><a href="#usage">Usage</a></li>

</ul>

<hr />

<h2><a name="intro">Introduction</a></h2>

<p>cvs2svn/cvs2bzr is a tool that can be used to migrate CVS
repositories to newer version control tools, including <a
    href="http://bazaar-vcs.org/">Bazaar</a>.  Bazaar is an adaptive
version control system that supports both centralised and distributed
version control. It is most famous for being used for Ubuntu and
MySQL development. The program used to convert to Bazaar, called
cvs2bzr, is distributed as part of the cvs2svn project.</p>

<p><strong>If you are reading this documentation on the <a
href="http://cvs2svn.tigris.org">cvs2svn website</a>, then please be
aware that it describes the current trunk version of cvs2svn, which
may be different than the most recent released version.  Please refer
to the documentation that was included with your version of cvs2svn.
</strong></p>

<p>Conversion to Bazaar was added in release 2.3 of cvs2svn and may have
improved significantly since then.  Please make sure you are using an
up-to-date version of cvs2svn--perhaps even the development trunk
version.</p>


<h2><a name="reqs">Requirements</a></h2>

<p>cvs2bzr requires the following:</p>

<ul>

  <li>Direct (filesystem) access to a copy of the CVS repository that
    you want to convert.  cvs2bzr parses the files in the CVS
    repository directly, so it is not enough to have remote CVS
    access.  See the <a href="faq.html#repoaccess">FAQ</a> for more
    information and a possible workaround.</li>

  <li>Python 2, version 2.4 or later.  See <a
    href="http://www.python.org/">http://www.python.org/</a>.
    (cvs2bzr does <strong>not</strong> work with Python 3.x.)</li>

  <li>If you use the <tt>--use-rcs</tt> option, then RCS's `co'
    program is required.  The RCS home page is
    <a href="http://www.cs.purdue.edu/homes/trinkle/RCS/"
            >http://www.cs.purdue.edu/homes/trinkle/RCS/</a>.
    See the <a href="cvs2svn.html#use-rcs"><tt>--use-rcs</tt> flag</a> for more
    details.</li>

  <li>If you use the <tt>--use-cvs</tt> option, then the `cvs' command
    is required.  The CVS home page is
    <a href="http://ccvs.cvshome.org/">http://ccvs.cvshome.org/</a>.
    See the <a href="cvs2svn.html#use-cvs"><tt>--use-cvs</tt> flag</a> for more
    details.</li>

  <li> Bazaar version 1.13 or later.</li>

  <li> The bzr-fastimport plugin version 0.9 or later.</li>

</ul>


<h2><a name="status">Development status</a></h2>

<p>Most of the work of converting a repository from CVS to a more
modern version control system is inferring the most likely history
given the incomplete information that CVS records.  cvs2svn has a long
history of making sense of even the most convoluted CVS repositories,
and cvs2bzr uses this same machinery.  Therefore, cvs2bzr inherits the
robustness and many of the <a href="features.html">features of
cvs2svn</a>.  cvs2svn can convert just about every CVS repository we
have ever seen, and includes a plethora of options for customizing
your conversion.</p>

<p>The output of cvs2bzr is a "fastimport" dump file that can be
imported into Bazaar using the <a
    href="https://launchpad.net/bzr-fastimport/">bzr-fastimport</a>
plugin.</p>

<p>Although cvs2bzr is considerably newer than cvs2svn, and much less
well tested, it is believed that cvs2bzr can (cautiously) be used for
production conversions. If you use cvs2bzr, please let us know how it
worked for you!</p>


<h2><a name="limitations">cvs2bzr limitations</a></h2>

<p>cvs2bzr still has many limitations compared to cvs2svn.  The main
cvs2svn developer has limited Bazaar experience and very limited time, so
<strong>help would be much appreciated!</strong> Some of these missing
features would be pretty easy to program, and I'd be happy to help you
get started.</p>

<ul>

  <li>The cvs2bzr documentation is still rather thin.  See <a
    href="#docs">below</a> for more references.</li>

  <li>CVS allows a branch to be created from arbitrary combinations of
    source revisions and/or source branches.  cvs2bzr tries to create
    a branch from a single source, but if it can't figure out how to,
    it creates the branch using "merge" from multiple sources.  In
    pathological situations, the number of merge sources for a branch
    can be arbitrarily large.</li>

  <li>There are no checks that CVS branch and tag names are legal
    names in Bazaar. This is unlikely to be a problem because Bazaar
    uses paths for branch names similar to CVS and Subversion. Tag
    naming in Bazaar is also more flexible than in git, say.</li>

  <li>Only single projects can be converted at a time.  Given the way
    Bazaar is typically used, I don't think that this is a significant
    limitation.</li>

  <li>cvs2bzr is not especially fast.  Among other things, it still
    uses RCS or CVS to extract the contents of the CVS revisions.
    Implementing the <tt>--internal-co</tt> option for cvs2bzr (using
    code that already exists in cvs2svn) might improve the conversion
    speed considerably.</li>

  <li>The cvs2svn test suite does not include meaningful tests of
    Bazaar output.</li>

  <li>cvs2bzr makes no attempt to convert <tt>.cvsignore</tt> files
    into <tt>.bzrignore</tt> files.</li>

  <li>cvs2bzr, like cvs2svn, does not support incremental conversion
    (i.e., tracking a live CVS repository).  However, this <a
    href="http://www.oak.homeunix.org/~marcel/blog/2009/06/03/tracking-cvs-with-git-using-cvs2git">possible
    workaround</a> for using cvs2git along those lines might provide
    some assistance for anyone wanting to try doing that using
    cvs2bzr.</li>

</ul>


<h2><a name="docs">Documentation</a></h2>

<p>There is some documentation specific to cvs2bzr, and much of the
cvs2svn documentation also applies fairly straightforwardly to
cvs2bzr.  See the following sources:</p>

<ul>

  <li>This document.</li>

  <li>The cvs2bzr man page and the output of <tt>cvs2bzr
    --help</tt>.</li>

  <li><a href="cvs2svn.html#intro">The cvs2svn documentation</a> and
    <a href="faq.html">the cvs2svn FAQ</a>, which contain much general
    discussion and describe many features that can also be used for
    cvs2bzr.</li>

  <li><tt>cvs2bzr-example.options</tt> in the cvs2svn source tree,
    which is an example of an options file that can be used to
    configure a cvs2bzr conversion.  The file is extensively
    documented.</li>

  <li>The cvs2svn mailing lists, etc., as described in <a
    href="faq.html#gettinghelp">the cvs2svn FAQ</a>.</li>

  <li>The <a href="http://doc.bazaar-vcs.org/migration/en/data-migration/">
    Bazaar Data Migration Guide</a>.</li>

</ul>


<h2><a name="usage">Usage</a></h2>

<p>This section outlines the steps needed to convert a CVS repository
to Bazaar using cvs2bzr.</p>

<ol>

  <li>Be sure that you have the <a href="#reqs">requirements</a>,
    including either RCS or CVS (used to read revision contents from
    the CVS repository).</li>

  <li>Obtain a copy of cvs2svn/cvs2bzr version 2.3 or newer.  It is
    recommended that you use the most recent version available, or
    even the development version.

    <ul>

      <li>To install cvs2svn from a <a
        href="http://cvs2svn.tigris.org/servlets/ProjectDocumentList">tarball</a>,
        simply unpack the tarball into a directory on your conversion
        computer (cvs2bzr can be run directly from this
        directory).</li>

      <li>

        <p>To check out the current trunk version of cvs2svn, make
          sure that you have Subversion installed and then run:</p>

<pre>
svn co --username=guest --password="" http://cvs2svn.tigris.org/svn/cvs2svn/trunk cvs2svn-trunk
cd cvs2svn-trunk
make man # If you want to create manpages for the main programs
make check # ...optional
</pre>

        <p>Please note that the test suite includes tests that are
          marked "XFAIL" (expected failure); these are known and are
          not considered serious problems.</p>

      </li>

    </ul>

  </li>

  <li>

    Configure cvs2bzr for your conversion.  This can be done via
    command-line options or via an options file:

    <ul>

      <li>The command-line options for running cvs2bzr are documented
        in the cvs2bzr man page and in the output of <tt>cvs2bzr
        --help</tt>.</li>

      <li>

        <p>The more flexible <a
          href="cvs2svn.html#cmd-vs-options">options-file method</a>
          requires you to create an options file, then start cvs2bzr
          with</p>

<pre>
cvs2bzr --options=OPTIONS-FILE
</pre>

        <p>Use <tt>cvs2bzr-example.options</tt> in the cvs2svn source
          tree as your starting point; the file contains lots of
          documentation.</p>

      </li>

    </ul>

  </li>

  <li>

    <p>Run cvs2bzr.  This creates an output file in <a
        href="http://www.kernel.org/pub/software/scm/git/docs/git-fast-import.html">fast-import</a>
    format.  The name of this file is specified by
    your options file or a command-line argument.  In the example,
    the file is named <tt>cvs2svn-tmp/dumpfile.fi</tt>.</p>

  </li>

  <li>

    <p>Load the dump file using bzr fast-import:</p>

<pre>
bzr fast-import cvs2svn-tmp/dumpfile.fi project.bzr
</pre>

  </li>

</ol>

<p>Feedback would be much appreciated, including reports of success
  using cvs2bzr.  Please send comments, bug reports, and patches to
  the <a
  href="http://cvs2svn.tigris.org/servlets/ProjectMailingListList">cvs2svn
  mailing lists</a>.</p>

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