I have been using Linux
/ BSD for over a decade, but Windows has always been my core work station, until recently. Software such as TortoiseSVN for Windows and SCPlugin for MAC, makes updating the WordPress Repository via Subversion somewhat simple. Even if you forget what to do, dozens if not hundreds of Websites clearly explain the process with nice pictures, videos, and explanations galore.
That basically all ends with Ubuntu. While several Websites explain Subversion, basically none of them explained updating the WordPress Repository using Ubuntu and Subversion in a nice clear step-by-step instructional process.
If you are new to the Repository or just confused how to update it on Ubuntu, then this step-by-step walk-through should clear up any confusions you have.