Linux Basics How to get a Command Line
When your system is working properly, the easiest way to access the command line is to run a terminal in your graphical desktop session.
In the event that your graphical interface is broken, you can still get a command line on virtual consoles (up to six of them can be accessible through the six key combinations of CTRL+ALT+F1 through CTRL+ALT+F6.
To get back to the graphical interface you can use the key combination CTRL+ALT+F7