What is UNIX ? #os #rtos #operatingsystem #linux #macos #cse #computerscience

What is Unix?
Unix -- trademarked as UNIX -- is a multiuser, multitasking operating system (OS) designed for flexibility and adaptability. Originally developed in the 1970s, Unix was one of the first OSes to be written in the C programming language. Since its introduction, the Unix operating system and its offshoots have had a profound effect on the computer and electronics industry, offering portability, stability and interoperability across a range of heterogeneous environments and device types.

History of Unix
In the late 1960s, Bell Labs (later AT&T), General Electric and the Massachusetts Institute of Technology attempted to develop an interactive time-sharing system called Multiplexed Information and Computing Service (Multics) that would enable multiple users to access a mainframe simultaneously.

Disappointed with the results, Bell Labs pulled out of the project, but Bell computer scientists Ken Thompson and Dennis Ritchie continued their work, which culminated in the development of the Unix OS. As part of this effort, Thompson and Ritchie recruited other Bell Labs researchers, and together, they built a suite of components that provided a foundation for the operating system. The components included a hierarchical file system, a command-line interface (CLI) and multiple small utility programs. The OS also brought with it the concepts of computer processes and device files.

A month later, Thompson deployed a self-hosting operating system with an assembler, editor and shell. The name, pronounced YEW-nihks, was a pun based on the earlier system -- an emasculated or eunuch version of Multics. Unix was much smaller than what the original developers intended for Multics, and it was a single-tasking system. Multitasking capabilities would come later.

Prior to 1973, Unix was written in assembler language, but the fourth edition was rewritten in C. This was revolutionary at the time because OSes were thought to be too complex and sophisticated to be written in C, a high-level language. This increased Unix's portability across multiple computing platforms.

In the late 1970s and early '80s, Unix amassed a strong following in academia, which led commercial startups, such as Solaris Technologies and Sequent, to adopt it on a larger scale. Between 1977 and 1995, the Computer Systems Research Group at the University of California, Berkeley developed Berkeley Software Distribution (BSD), one of the earliest Unix distributions and the foundation for several other Unix spinoffs.

In 1991, Linus Torvalds, a student at the University of Helsinki, created a Unix-based OS for his PC. He would later call his project Linux and make it available as a free download, which led to the growing popularity of Unix-like systems. Today, a variety of modern servers, workstations, mobile devices and embedded systems are driven by Unix-based OSes, including macOS computers and Android mobile devices.

[williamcorcoran]

UNIX is not an acronym. Initially, it was called UNICS and that was a pun on MULTICS. It was called UNICS because it was humorously said to be a “castrated MULTICS”.

The spelling was later changed to UNIX. But, in all cases it was not an acronym.