Download from SVN

 Subversion is a version control software that allows users to download the very latest version of a branch, without having to wait for someone to get around to packaging it. Advantages to using Subversion include the latest version, vastly simplified updating, the ability to roll back an upgrade, the ability to create and submit patches.

See Subversion for more details; below are some quick directions for a couple common tasks.

Prerequisites
You must have a Subversion client installed before you can use it. (Although you can theoretically download files without Subversion, this would mean tediously downloading each individual file manually.) The recommended software is the official Subversion client, available from the Subversion project page. Note that this client uses a command-line interface, which the instructions below use. Alternatively, you can get subversioning software To download from the latest stable 1.9 release (recommended), enter the following command from the command-line in the directory you wish to download to:

svn checkout http://svn.wikimedia.org/svnroot/mediawiki/branches/REL1_9/phase3

Alternately, you can download the latest bleeding-edge development version used by the Wikimedia Foundation using the following command:

svn checkout http://svn.wikimedia.org/svnroot/mediawiki/trunk/phase3

Installing
Normal installation rules apply, but for best results, use PHP 5.1.2 as an Apache module (SAPI). 1.7alpha requires PHP5, and will usually crash PHP if FastCGI is being used.

Upgrading and downgrading
Upgrading between releases with SVN is simple. If you have direct access to the command-line on the server, you can enter the commands below directly; alternatively, you can maintain a copy on a local machine and upload updated versions to the server.

To upgrade MediaWiki, simply use the command below in the root of the installation directory. Note that this will upgrade to the latest version of the current major version. If you are using MediaWiki 1.6, this will upgrade to any version 1.6.x, but not to 1.7:

svn update

To upgrade to another release branch (version 1.7 in the example above) or to switch between individually-selected version tags, you can use the "switch" command (substituting the appropriate versions):

svn checkout http://svn.wikimedia.org/svnroot/mediawiki/tags/REL1_6_2/phase3 svn switch http://svn.wikimedia.org/svnroot/mediawiki/tags/REL1_6_3/phase3

Don't forget to run maintenance/update.php every once in a while, especially if things start acting strangely.