Author Topic: What Is POSIX? How It Relates to Linux  (Read 30 times)

Offline javajolt

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What Is POSIX? How It Relates to Linux
« on: January 16, 2022, 09:34:41 PM »
Every Linux user has heard of POSIX at least once. But what does it mean and how is it related to Linux?

When you use Linux, you may hear people talking about POSIX compliance. What does that mean? This article will explain POSIX's relation to Linux and the attempt to standardize operating systems.


In the 1980s, Unix systems were gaining popularity in business and academia, but there were already two major variants: AT&T's System V and the University of California's Berkeley Software Distribution, or BSD. To make things even more complicated, Unix vendors would change things around on their own systems, such as offering "System V with BSD enhancements."

Like now, the Unix market was then fragmented. There was a growing sense of need among the Unix community to standardize the system.

The Institute of Electrical and Electronics Engineers (IEEE) began to draft a standard for operating systems, using Unix as a starting point. The standard 1003, was named "POSIX" for Portable Operating System Interface in 1988. The name was even coined by Richard Stallman.

The US Government required certain large computer purchases to be compliant with POSIX under FIPS-151. Today, POSIX standards are developed by the Austin Group, a joint effort with the IEEE, The Open Group, and ISO/IEC JTC 1.

POSIX Standards

The idea behind POSIX is that a developer should create an application and have it work on any system that complies with the standard.

The POSIX standard that will affect most end-users is POSIX.2, which governs the behavior of the shell and various standard utility programs.

On a POSIX-compliant system, all of the options should be the same, no matter which operating system variant you're using.

The other POSIX standards are mainly of interest to programmers. These include everything from threads to the standard C library.