What is Linux, GNU and GPL?

Linux is an open-source operating system. An operating is system software that manages the computer hardware. It enables the execution of application programs and acts as an interface between the computer user and the computer hardware.

Linus Torvalds created Linux kernel in 1991. He was studying computer science at the University of Helsinki in Finland where he had been using a paid version of Unix-like operating system called Minix. He was unhappy with Minix and then decided to write a complete Unix-like proprietary kernel called Linux. He used C programming language to write a Linux kernel and its functionality is similar to UNIX.

There are two ways to work with a Linux system:

A graphical user interface.

A command-line interface.

Features of Linux

• Portability: Linux is a portable software that means it can work on different types of hardware in the same way.
• Multitasking: In Linux, multiple applications can run at the same time.
• Multi-user: Multiple users can access the system resources like memory, ram, and application programs at the same time.
• Security: Linux provides a firewall or Iptables and SElinux (Security Enhance Linux), user security using authentication features like password protection with hashing algorithms, access control list to specific files and encryption of data.
• Shell: Linux provides a special interpreter called BASH (Bourne again shell) that process commands. A shell interpreter takes command from a user in plain text format and tells the operating system to run the task.
• Open source: Linux source code is available for free so anyone can download, modify as per your needs or requirements.
• File System: Linux file system is in a hierarchical format.

GNU Project

In 1983, Richard Stallman began the development of free software replacement for UNIX and it’s called GNU.

GNU is a short form of (GNU’s Not Unix). It is a free operating system but it was the missing kernel for the operating system and in 1992 Linus Torvalds join the GNU project with he’s Linux Kernel so it’s become GNU/Linux.

There are four main purposes of the GNU project is to give computer users a:  

Freedom to study the source code and changed and run the program as you wish.

Freedom to modify the code or program to suit your needs.

Freedom to share copies, either for free or for fees.

Freedom to distribute a modified version of the program to contribute to your community so they can get benefit from it.

GNU GPL (General Public License)

Any software licensed under GPL is free licensed software. The end users get the freedom to study, share, modify and run the software under GPL.

The first version was published in February 1989, the second version was published in June 1991 and the latest the third version was published in June 2007.

Under the GPL license program you are allowed to sell the modified version of the software. You are also allowed to introduce additional points in terms and conditions.