Watch for and run scripts when locking and unlocking an Ubuntu desktop
When a lock or unlock event occurs all executable files with a .sh suffix in
the scripts/lock or scripts/unlock directory are run.
The lock/unlock scripts are executed by run-parts and the order in which the
execution occurs is lexical sort order of the files names.
If you need to ensure an execution order I would recommenced naming your scripts
like this 00-my-script.sh and 10-my-second-script.sh
By default this script listens for events from the MATE
screen saver to detect the locking and unlocking but it will work for Gnome or Unity
to if you use the --system mate|gnome|unity flag