1.   What is shell?

shell is a program that takes commands from the keyboard and gives them to the operating system to perform

2. what is terminal ?

A computer terminal is an electronic or electromechanical hardware device that can be used for entering data into, and transcribing data from, a computer or a computing system

3.What is user friendly in between terminal and GUI & why?

GUI is more user-friendly, and CLI is more advanced and powerful.

4.   What defines a user account?

A user account is an identity created for a person in a computer or computing system. User accounts can also be created for machine entities, such as service accounts for running programs, system accounts for storing system files and processes, and root and administrator account for system administration

5.   What is root user?

The root is the user name or account that by default has access to all commands and files on a Linux or other Unix-like operating system.

6.   What is general purpose user?

A general-purpose computer is one that, given the appropriate application and required time, should be able to perform most common computing tasks. Personal computers, including desktops, notebooks, smartphones and tablets, are all examples of general-purpose computers.

7.   What are the difference between root user and general purpose user?

"root" is the actual name of the administrator account. "sudo" is a command which allows ordinary users to perform administrative tasks. ... Root user has user id 0 and nominally has unlimited privileges. Root can access any file, run any program, execute any system call, and modify any setting

8.   What is the meaning of sudo?

It originally stood for "superuser do" as the older versions of sudo were designed to run commands only as the superuser. 

9.   What is the meaning of su?

Substitute user

10.  Why we use sudo?

 "Sudo allows a system administrator to delegate authority by giving certain users the ability to run some commands as root or another user while providing an audit trail of the commands and their arguments.

11. why do we use su ?

The most common use of the su is to get superuser privileges. It is often mistaken as an abbreviation for “superuser”, but it is an abbreviation for “substitute user”. When using su, we can run it with or without the – argument

12.  How to create a user account?

sudo adduser user_name

13.  How to delete a user?

sudo deluser user_name

14 How to login into a user account?

sudo login user_name

15 How to logout from a user account?

logout

16 How many times it requires password for creating a user account?

2 times

17 How to exit from root?

press CTRL + D

18 What is the meaning of sudo adduser {username}?

creating user account

19 What is the meaning of deluser {username}?

deleting user account

20 What is the meaning of sudo su?

Running sudo su - and then typing the user password has the same effect the same as running su - and typing the root password