Upgrading mtrack is usually just a simple matter of pulling the latest changes from the mercurial repository. It is sometimes necessary to change the database schema.
If you are using PostgreSQL as your database backend, we strongly recommend that you take a backup of your mtrack database prior to running an upgrade; while we endeavor to make the upgrade process smooth and atomic, having a backup prepared puts you in a much more comfortable position in the case where something does go wrong.
If you are using the default SQLite database backend, the upgrade procedure will automatically make a copy of your mtrac.db file before making any changes. This backup will be stored in your vardir. The upgrade procedure will never delete this, so you are encouraged to remove this file for yourself once you are satisfied with the upgrade.
$ hg pull $ hg updated $ php bin/schema-tool.php