Track your changes to an open-source project with git

Here are quick and easy steps to track your changes to an open-source project.

Once you get a handle on git, you'll find it very powerful. But getting started can be the biggest challenge. Distributed source control requires a different way of thinking than using a central repository. Use this to get past the first hurdles.

Requirements

Before you can start making changes to a project, you should get the code and make sure you can compile and run it. In this guide, we assume that the project is currently under SVN control. Check out a copy and get it up and running.

The next set of requirements is pretty simple:

• I need my own branch off of the svn branch.
• I need the ability to overlay the latest svn changes, over time, on top of changes in my branch.

Notice how simple this is - we're not even asking to commit anything yet. These are fundamental requirements that any developer on a non-trivial open-source project would have. You need to do this if you are going to bang on an open-source project.

Now let's add one more requirement. I'm going to have this code on at least three different machines, so I need to be able to have a common repository for my changes.

• ability to work from several locations, pushing/pulling my changes to a central repo

Another basic source control requirement, and we're done.

But try to meet this set of requirements with CVS or subversion (SVN). No longer simple. Enter git.

Setup

NOTE: I'm going to use mythtv in this example, because that's what I wanted to work on.

Create a local git repository of the project's subversion repository, using git-svn. There are two ways to do this. If you do not specify a SVN revision number, git will grab the entire history of the project as it is available in the SVN repo. WARNING: this may be HUGE for older bigger projects!

git-svn clone http://svn.mythtv.org/svn/trunk/mythtv mythtv

If you specify a revision number, git will grab just that version, and then we can grab all changes after that version, too. It's probably worth digging into the project history to find a reasonable revision number.

git-svn clone -r15502 http://svn.mythtv.org/svn/trunk/mythtv mythtv

We now have a repo of the project under git control. Simple, eh?

tbc...