Difference between Unix, Linux, and Ubuntu. What do they actually mean?

When I started learning about Operating systems, I was totally confused about their differences. Because I found that the name Unix, Linux, Ubuntu are used interchangeably. So I can not get their differences completely. And many of the new learners find these terms confusing. For that reason, in this article, I try to explain these terms in as much plain English as possible.

First, In a broad sense, all of the above terms(Unix, Linux, Ubuntu) are referring to the operating system and they are closely related to each other but not the same.

Unix

Unix (1970) is an operating system with some core features like:

1. Multi-tasking (Running multiple applications like a text editor, audio player, pdf reader at the same time)
2. Multi-user (Different people logged in a single system at the same time)
3. Cross-platform (A convenient platform for programmers to develop applications and run on that system and other Unix like systems)

After developing Unix, It has become popular among academics and startups. So commercial startups and academics made different OS based on those Unix core features. Some popular examples are — BSD, HP-UX, Solaris, AIX, and Xenix and Linux based operating systems (Debian, Red Hat, Ubuntu) and macOS.

Some important information about Unix:

• Unix is developed in the late 1970s by a bunch of computer scientists(Dennis Ritchie, Ken Thompson, and many others) in Bell Labs.
• Unix is written in C programming language.
• Unix follows POSIX standard, which is a standard specified by IEEE which provides an interface for applications to communicate with the kernel.
• Unix system is developed in a modular way, so the whole system is divided into many components. These components are independent of each other. That means one component does not affect the other components.

Before going to Linux, we should remember these core features of Unix: multi-user and multitasking.

Linux

Linux has generally referred to a family of open-source software and operating system based on the Linux kernel. That means any operating system(Ubuntu, Kubuntu, Android OS and etc) based on Linux kernel are called Linux or Linux based operating system. Actually, Linux is only a kernel. And only the kernel doesn’t make an operating system. The operating system needs a file system, device drivers, and many other applications. Linux took most of those applications from GNU projects by the Open software foundation. That is why Linux is generally called GNU/Linux.

So why Linux is called a Unix-like operating system or why Unix and Linux are used interchangeably?

Linux is a Unix-like operating system developed in 1991 by Linus Torvalds. Here Unix like means, Linux follows ideas from Unix core features( multi-tasking and multi-user). Linux is not a copy or use the kernel of Unix. Linux just borrows the idea of Unix features and implement these ideas in its own way.

What was the reason for developing this new operating system Linux while there was Unix exists?

Unix is a great operating system no doubt but the licensing of Unix is complex and not free. Frustrated by the licensing of Unix, Linus Torvalds, an operating system scientist, start developing an operating system Kernel which is later named Linux. The advantage of Linux over Unix is that it is completely free and licensing is very convenient. So that anyone can see the source code and contribute to this system.

Why Linux is sometimes called GNU/Linux?

Free software foundation is developed with a motive of a Unix-like free operating system and related software. This project is called GNU. This project made many applications and utility software for Unix and Unix-like operating systems. They also made a Unix like kernel named GNU Hurd. But later it is proved that the Linux kernel made by Linus Torvalds is a better option. So Linux kernel with Free software and applications made by the GNU project make a complete operating system. That is why Linux is also called GNU/Linux.

It is better to know that Most of the software used in Linux is from GNU projects but there are also many volunteers who contribute much software for the Linux system.

Some important information about Linux:

• There are many Linux distribution: Debian, Ubuntu, Kubuntu, Red Hat, Android. All of these operating systems use the Linux kernel.
• Linux is actually built on Debian architecture. Debian is one of the early Linux distribution developed in 1993.
• Linux is the most popular operating system around the world. Android devices play an important role in it by using the Linux kernel.

Before going to Ubuntu we should remember these points:

1. Linux is a kernel.
2. GNU software + Linux kernel makes an operating system.
3. Linux is Unix like because it follows Unix core features(Multi-tasking and multi-user)

Ubuntu

Why Ubuntu is called Linux or UNIX?

Linux is the kernel of Ubuntu, so it is called Linux distribution or sometimes Linux. And in the same way, Linux follows Unix standard so Ubuntu is also called a Unix-like operation system or sometimes Unix.

So in a nutshell, we can say:

Unix : (1970) is the first multitasking and multi-user operating system.

Free software foundation: (1984) is founded to make a kernel and related software Like Unix system for free. The project is called GNU.

Linux : (1991) Linux is a kernel followed Unix core features. Linux kernel and Gnu software: make the GNU/Linux operating system.

Ubuntu: (2004) is an operating system based on Linux Kernel. Ubuntu is the most popular Operating system among all the Linux distributions.

Originally published at http://mithunranjon.blogspot.com on January 28, 2018.