Now that I’ve been using WordPress for a while, I wanted to simplify the upgrade process. Like many users, I’ve customized my WordPress installation enough that doing the unzip over the top just does not feel safe. I’ve wanted a Unified Diff for a while, but have just been lazy about it. WordPress uses Subversion to manage their source code, so it is pretty easy to do. Here’s what you need to do.

Edit: You will need shell access to the server as well as the Subversion client installed. 

Note: BACKUP YOUR WORKING COPY! I will take NO responsibility for broken WordPress installations!

1. run svn diff http://svn.automattic.com/wordpress/tags/2.3.1 http://svn.automattic.com/wordpress/tags/2.3.2 > wp-upgrade.patch to get your unified diff patch file. Keep in mind, just change the versions at the end of those URLs to the versions you are upgrading. The first version number should be your current WordPress version, the second should be the one you want to upgrade to.
2. Check to see what the patch is doing, and make sure it is not dinking with anything in the wp-content directory… If so, review those patches carefully and optionally remove them.
3. Disable all the plugins.
4. Move the patch file into the directory for the WordPress installation you are upgrading.
5. Run patch -p0 < wp-upgrade.patch (Note: you may need to do this as a super user depending on permissions)
6. Be sure that patched file owners/permissions match the existing owners/permissions.
7. Go to http://www.yoursite.foo/wp-admin/upgrade.php.
8. Reactivate plugins.

Then you are all done! I hope this makes your upgrading process feel safer!