Downloading SpamAssassin from SVN
The latest development version can be obtained at any given time from the SpamAssassin Subversion (SVN) repository. Please note that this code can be quite unstable and we don't recommend running it on real or important mail unless you really know what you are doing.
To do this, you will need to install subversion. [http://subversion.tigris.org/ Subversion website] [http://svnbook.red-bean.com/ Subversion book]
Downloading via anonymous SVN
$ svn checkout http://svn.apache.org/repos/asf/incubator/spamassassin/trunk spamassassin/
This will put the latest (trunk) version of spamassassin in the directory spamassassin/.
Downloading via authenticated SVN (developers only)
$ svn checkout https://svn.apache.org/repos/asf/incubator/spamassassin/trunk spamassassin
Authentication will allow you to commit your changes to the SpamAssassin tree.
Commit access is generally given if you have a history of making valuable contributions to SpamAssassin in the form of patches.
Using Subversion
Updating your tree
$ svn update
This command should update your local tree to reflect changes made on the server. Do this periodically, especially before submitting a patch.
Creating a patch
$ svn diff
This will create a unified diff (patch-file) with the differences between your local tree and the server's copy. Be sure to update before you do this to ensure there are no conflicts.
More information
For more information, try "svn help" and reading the [http://subversion.tigris.org/ Subversion website] and the [http://svnbook.red-bean.com/ Subversion book].
(DuncanFindlay)