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The Portable Operating System Interface (POSIX) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems.[1] POSIX defines both the system- and user-level application programming interfaces (API), along with command line shells and utility interfaces, for software compatibility (portability) with variants of Unix and other operating systems.[1][2] POSIX is also a trademark of the IEEE.[1] POSIX is intended to be used by both application and system developers.[3]
Contents
1 Name
2 Overview
3 Versions
3.1 Parts before 1997
3.2 Versions after 1997
3.2.1 POSIX.1-2001 (with two TCs)
3.2.2 POSIX.1-2008 (with two TCs)
3.2.3 POSIX.1-2017
4 Controversies
4.1 512- vs 1024-byte blocks
5 POSIX-oriented operating systems
5.1 POSIX-certified
5.2 Formerly POSIX-certified
5.3 Mostly POSIX-compliant
5.3.1 POSIX for Microsoft Windows
5.3.2 POSIX for OS/2
5.3.3 POSIX for DOS
5.3.4 Compliant via compatibility layer
6 See also
7 References
8 External links
Name
Originally, the name "POSIX" referred to IEEE Std 1003.1-1988, released in 1988. The family of POSIX standards is formally designated as IEEE 1003 and the ISO/IEC standard number is ISO/IEC 9945.
The standards emerged from a project that began around 1985. Richard Stallman suggested the name POSIX (pronounced as pahz-icks, as in positive, not as poh-six) to the IEEE instead of former IEEE-IX. The committee found it more easily pronounceable and memorable, and thus adopted it.[1][4]
Overview
Unix was selected as the basis for a standard system interface partly because it was "manufacturer-neutral". However, several major versions of Unix existed—so there was a need to develop a common-denominator system. The POSIX specifications for Unix-like operating systems originally consisted of a single document for the core programming interface, but eventually grew to 19 separate documents (POSIX.1, POSIX.2, etc.).[5] The standardized user command line and scripting interface were based on the UNIX System V shell.[6] Many user-level programs, services, and utilities (including awk, echo, ed) were also standardized, along with required program-level services (including basic I/O: file, terminal, and network). POSIX also defines a standard threading library API which is supported by most modern operating systems. In 2008, most parts of POSIX were combined into a single standard (IEEE Std 1003.1-2008, also known as POSIX.1-2008).
As of 2014, POSIX documentation is divided into two parts:
POSIX.1, 2013 Edition: POSIX Base Definitions, System Interfaces, and Commands and Utilities (which include POSIX.1, extensions for POSIX.1, Real-time Services, Threads Interface, Real-time Extensions, Security Interface, Network File Access and Network Process-to-Process Communications, User Portability Extensions, Corrections and Extensions, Protection and Control Utilities and Batch System Utilities. This is POSIX 1003.1-2008 with Technical Corrigendum 1.)
POSIX Conformance Testing: A test suite for POSIX accompanies the standard: VSX-PCTS or the VSX POSIX Conformance Test Suite.[7]
The development of the POSIX standard takes place in the Austin Group (a joint working group among the IEEE, The Open Group, and the ISO/IEC JTC 1/SC 22/WG 15).