Linux: A Comprehensive Guide to Linux Operating System and Command Line

Introduction

The term Linux refers to an operating system, or kernel, developed by Linus Torvalds and a few other contributors. It was publicly released for the first time in September 1991 and its introduction completely changed how users would experience computing for personal and professional purposes. In a world where Microsoft was charging users for the Windows operating system, Linux was offered to the world as an open-source operating system. This meant that it was free of cost and allowed programmers to customize it as per their requirements. They could use the kernel to create their customized version of an operating system around it. The primary code used for developing the Linux operating system was in the C programming language. 

The Linux kernel is used by thousands of operating systems today, and the most popular ones among them comprise Debian, Ubuntu, RedHat, and Fedora. This list is not limited to just the four of these, as new operating systems are developed every year that employ the kernel from the original Linux system. 

Mankind reached a milestone in computing technology with Linux's invention and today, Linux powers almost all our devices such as mobiles, laptops, cloud servers, and other supercomputers. 

This also led to the creation of a popular job profile known as a Linux System Administrator. The responsibilities of a Linux system admin revolve around the following tasks:

Knowledge of the Linux file system

Managing the Linux system's superuser known as Root

Proficiency in the Linux command line

Managing users, files, and directories

It is similar to maintaining your personal computer at home but on a larger scale where you are responsible for an entire organization's computer system. 

Almost every business today that deals with data and data-related applications uses a Linux based computer known as a server. A Linux server manages all the interactions between a business and its customers, and therefore, it manages huge amounts of customer data. In today's world, data is the new currency and is of utmost importance to a business. If a Linux server is kept down for a long period, it can result in losses worth thousands of dollars for a business. Let us take an example of the shopping giant, Amazon's website. If the Amazon website went off the Internet even for five minutes, its sales would suffer hugely. This is where Linux knowledge helps and a Linux system admin would save the day. It is the Linux system admin's responsibility to ensure that the Linux system is always up and running and that the website of business never goes off the Internet, even for a second.

This is just one of the many jobs that involves the knowledge and use of the Linux operating system. In the following chapters, we will discuss more about Linux, its origins, its uses, and how it works!

Chapter 1: Features of Linux

Linus Torvalds studied at the University of Helsinki and regularly used Minix, a version of the UNIX operating system. He and a few others realized that a few modifications could make this operating system even more efficient and sent a request to the developer of Minix, Andrew Tanenbaum for these changes. Andrew, however, felt that these changes were irrelevant and discarded their request. This was when Linus decided to create his own operating system that would be developed based on feedback from end-users. He started coding in C language, wrote 95% of Linux in C, and coded the rest in the Assembly language that, at the time, was the second most popular language. 

What Kind of Operating System is Linux?

Linux can be classified as a Layered Architecture Operating System, comprising the following layers:

Hardware Layer

This consists of all peripheral devices such as Hard Disk, RAM, CPU, etc. 

Kernel

The kernel is the heart of the operating system. It lies between the software and hardware, and all instructions regarding input and output are processed via the kernel. 

Shell/GCC

The shell is an interface that lies between the user and the Linux kernel. The shell hides the complexity of the kernel's functions. The shell takes commands from a user as inputs and then instructs the kernel to execute those commands. 

Application Software

Software is a utility offered by the