Single UNIX Specification: Difference between revisions

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The '''Single UNIX Specification''' is the collective name of a family of standards developed and maintained by the [[Austin Group]]. It is based on earlier work by the [[IEEE]] and [[The Open Group]] and currently published as the Single UNIX Specification Version 3, and also as The Open Group Base Specifications, '''IEEE Standard 1003.1 (POSIX)''' and '''ISO/IEC 9945'''. The standards emerged from a project, begun circa [[1985]], to standardise the [[API|application program interface]] for software designed to run on variants of the [[UNIX]] [[OS|operating system]].

[[pl:Single UNIX Specification]]

[[The Open Group]] publishes a document called the '''Single UNIX Specification''' that defines how a [[Unix|UNIX system]] should behave.

There have been two versions of this document.

Its content derives heavily from the [[POSIX]] specification, but the Single UNIX Specification has as of 2001 become more popular among operating system developers than the POSIX specification, largely because the Open Group makes its document available at a much lower price.

Previously, The Open Group's Single UNIX Specification was separate from the official IEEE POSIX. The near-equivalent Single UNIX Specification became more popular because it was available for free, whereas the IEEE charged a substantial fee for access to the POSIX specification. Beginning in [[1998]] a joint working group, the Austin Group, began to develop the combined standard that would be known as the Single UNIX Specification.

As of version 3 the specification contains four sections:

*'''Base Definitions and Headers'''<br>(a list of definitions and conventions used in the specifications and a list of [[C programming language|C]] header files which must be provided by compliant systems)

*'''System interfaces'''<br>(a list of available C system calls which must be provided)

*'''Shell &amp; Utilities'''<br>(a list of utilities and a description of the shell, [[Bourne shell|sh]])

*'''Rationale'''<br>(the explanation behind the standard)

The user and software interfaces to the OS are specified in four main sections:

==External links==

* [http://www.opengroup.org/onlinepubs/007908799/ Text of the Single UNIX Specification, version 2]

* '''Base Definitions and Headers'''<br>(a - A list of definitions and conventions used in the specifications and a list of [[C|C programming language|C]] header files which must be provided by compliant systems).

* [http://www.opengroup.org/onlinepubs/007904975/ Text of the Single UNIX Specification, version 3]

* '''Shell &amp;and Utilities'''<br>(a - A list of utilities and a description of the shell, [[sh|Bourne shell|sh]]).

* '''System interfacesInterfaces'''<br>(a - A list of available C system calls which must be provided).

* '''Rationale'''<br>(the - The explanation behind the standard).

The standard user command line and scripting interface is the [[Korn shell]]. Other user-level programs, services and utilities include [[awk]], [[echo]], [[ed]], and numerous (hundreds) others. Required program-level services include basic [[I/O]] ([[file]], [[terminal|computer terminal]], and [[network]]) services.

A test suite accompanies the standard. It is called '''PCTS''' or the '''Posix Certification Test Suite'''.

For [[Linux]] systems, several common extensions and complementary de facto-standards are provided by the [[Linux Standard Base]].

== Related pages ==

* [[Native POSIX Thread Library]]

== External links ==

* [http://www.opengroup.org/onlinepubs/007908799007904975/ Text of the Single UNIX Specification, versionVersion 23]

* [http://www.pasc.org/ The Portable Application Standards Committee]