We saw in the first recipe how to install Odoo from source by using the git repository. The main benefit of this setting is being able to update the source code of Odoo using git to get the latest bug fixes.
Stop any instance currently running with the Odoo source you are about to update.
Make a backup of all the databases you care about in case something goes bad. This is obviously something you need to do for production databases. See the Managing Odoo server databases recipe for instructions.
Then make a note of the current version of the source you are running. The best way is to create a lightweight tag using the following command:
$ cd ~/odoo-dev/odoo $ git checkout 9.0 $ git tag 9.0-before-update-$(date ...