Overview
The POSIX specifications for Unix-like operating system environments originally consisted of a single document for the core programming interface, but eventually grew to 19 separate documents (for example, POSIX.1, POSIX.2 etc.) . The standardized user command line and scripting interface were based on the Korn shell. 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) services. POSIX also defines a standard threading library API which is supported by most modern operating systems. Nowadays, most of POSIX parts are combined into a single standard, IEEE Std 1003.1-2008, also known as POSIX.1-2008.
As of 2009, POSIX documentation is divided in two parts:
- POSIX.1-2008: 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)
- POSIX Conformance Testing: A test suite for POSIX accompanies the standard: PCTS or the POSIX Conformance Test Suite.
The development of the POSIX standard takes place in the Austin Group, a joint working group linking the Open Group and the ISO organization.
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