The PORTABLE OPERATING SYSTEM INTERFACE (POSIX) is a family of
standards specified by the
IEEE Computer Societyfor maintaining
compatibility between operating systems .
application programming interface (API), along with command line
shells and utility interfaces, for software compatibility with
* 1 Name * 2 Overview
* 3 Versions
* 3.1 Parts before 1997
* 3.2 Versions after 1997
* 3.2.1 POSIX.1-2001 * 3.2.2 POSIX.1-2004 (with two TCs) * 3.2.3 POSIX.1-2008 (with two TCs)
* 4 Controversies
* 4.1 512- vs 1024-byte blocks
* 5 POSIX-oriented operating systems
* 5.1 POSIX-certified
* 5.2 Mostly POSIX-compliant
* 6 See also * 7 References * 8 External links
Originally, the name "POSIX" referred to IEEE Std 1003.1-1988, released in 1988. The family of POSIXstandards is formally designated as IEEE 1003 and the international standard name is ISO /IEC 9945.
The standards emerged from a project that began circa 1985. Richard Stallman suggested the name _POSIX_ to the IEEE instead of former _IEEE-IX_. The committee found it more easily pronounceable and memorable, and thus adopted it.
As of 2014 , POSIXdocumentation is divided in two parts:
* POSIX.1, 2013 Edition:
POSIXBase 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
PARTS BEFORE 1997
Before 1997, POSIXcomprised several standards:
* POSIX.1: Core Services (incorporates Standard ANSI C) (IEEE Std 1003.1-1988)
* Process Creation and Control
* Floating Point Exceptions
* Segmentation / Memory Violations
* Illegal Instructions
* Bus Errors
* POSIX.1B: Real-time extensions (IEEE Std 1003.1b-1993, later appearing as librt—the Realtime Extensions library) )
* Priority Scheduling * Real-Time Signals * Clocks and Timers * Semaphores * Message Passing * Shared Memory * Asynchronous and Synchronous I/O * Memory Locking Interface
* POSIX.1C: Threads extensions (IEEE Std 1003.1c-1995)
* Thread Creation, Control, and Cleanup * Thread Scheduling * Thread Synchronization * Signal Handling
* POSIX.2: Shell and Utilities (IEEE Std 1003.2-1992)
* Command Interpreter * Utility Programs
VERSIONS AFTER 1997
_POSIX.1-2001_ (or IEEE Std 1003.1-2001) equates to the _Single UNIX Specification version 3._
This standard consisted of:
* the Base Definitions, Issue 6, * the System Interfaces and Headers, Issue 6, * the Commands and Utilities, Issue 6.
POSIX.1-2004 (with Two TCs)
IEEE Std 1003.1-2004 involved a minor update of POSIX.1-2001. It incorporated two minor updates or errata referred to as _Technical Corrigenda_. Its contents are available on the web.
POSIX.1-2008 (with Two TCs)
As of 2017 , _Base Specifications, Issue 7_ (or _IEEE Std 1003.1-2008_, 2016 Edition) represents the current version. A free online copy is available.
This standard consists of:
* the Base Definitions, Issue 7, * the System Interfaces and Headers, Issue 7, * the Commands and Utilities, Issue 7, * the Rationale volume.
512- VS 1024-BYTE BLOCKS
POSIXmandates 512-byte default block sizes for the df and du
utilities, reflecting the typical size of blocks on disks. When
POSIX-ORIENTED OPERATING SYSTEMS
Depending upon the degree of compliance with the standards, one can classify operating systems as fully or partly POSIXcompatible. Certified products can be found at the IEEE's website.
Some versions of the following operating systems have been certified to conform to one or more of the various POSIXstandards. This means that they passed the automated conformance tests.
_ THIS SECTION NEEDS EXPANSION. You can help by adding to it . (January 2007)_
The following, while not officially certified as POSIXcompatible, comply in large part:
* Android (Available through Android NDK)
BeOS(and subsequently Haiku )
* Darwin (core of OS X/macOS and iOS )
Cygwinprovides a largely POSIX-compliant development and run-time
* ^ "POSIX.1 FAQ". The Open Group. 5 October 2011. * ^ _A_ _B_ " POSIX1003.1 FAQ Version 1.12". 2 February 2006. Retrieved 16 July 2006. * ^ "POSIX". _Standards_. IEEE. * ^ "The origin of the name POSIX.". 2011. Retrieved 28 September 2013. * ^ PASC Status (including POSIX) (Report). IEEE Computer Society. 2003-12-04. Retrieved 2015-03-01. * ^ "Shell Command Language - The Open GroupBase Specifications Issue 7, 2013 Edition". * ^ "POSIX". The Open Group. * ^ "librt(3LIB)". _docs.oracle.com_. man pages section 3: Library Interfaces and Headers. Oracle Corporation. 1998-08-04. Retrieved 2016-02-18. librt, libposix4- POSIX.1b Realtime Extensions library librt is the preferred name for this l