We will start this training on RHEL7.3 Normally there are 3 ways to interact with any OS- 1. GUI(graphical user interface) - In simple words we can say interacting with OS using mouse. This the same way you are interacting with Windows. 2. CLI(Command line interface) - In this way user can't use mouse because there we don't have any graphics(icons/buttons) so that you can double click and open the things and select etc. 3. API(Application programming interface) - Normal user don't this, it is specially for developers Here I'll talk about CLI, whatever things you do in GUI, 99% of them you can do from CLI as well. The beauty of CLI is that we can do the things very fastly and also it requires very limited/less resource(compute unit or we can say RAM/CPU etc..). Let's take an example how CLI is faster than GUI- Use case: Open 100 terminals - This task can be completed in two way (A) - GUI(Right Click on home screen and then select open terminal, same thi