Preparation on the system

$[$Screenshot$]$ Create and add content to a new file $($when you are root$)$ called

$$rootfile$$ under the non$-$root user$$s home directory.

$$ Log on to the system as the non$-$root user in a new terminal. Starting from here you

are an invader who only knows the non$-$root user$$s username and password but

intend to escalate yourself to a root user$)$