Ofris is an application which serves to lock the system or freeze. Or in other words Ofris is a application similar to Deep Freeze that runs on Linux operating system.
sudo add-apt-repository ppa:tldm217/tahutek.net
sudo apt-get update
sudo apt-get install ofris-en
How to run Ofris:
open a terminal and run :
And then select what you want to do, freeze the system for this user or for another user.
You can later unfreeze the system the same way.