POSIX
POSIX is the collective name of a family of related
standards defined by the
IEEE and formally designated
IEEE 1003. The international standard name is
ISO/
IEC 9945. The standards emerged from a project, begun circa
1985, to standardise the
application program interface for software designed to run on variants of the
UNIX OS. The term
POSIX was suggested by
Richard Stallman in response to an IEEE request for a memorable name. It is a near
acronym for
Portable Operating System Interface, with the
X signifying the UNIX heritage of the API.
POSIX specifies the user and software interfaces to the OS in some 15
different documents. 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, and network) services.
A test suite for POSIX accompanies the standard. It is called PCTS or the Posix Conformance Test Suite.
Since the IEEE has been charging very high rates for POSIX documentation
and not allowing on-line publication of the standards,
there has been a tendency toward the "Single UNIX Specification" standard, which is open, accepts input from anyone, and is freely available on the Internet. It is made by The Open Group.
For Linux systems, several common extensions and complementary de facto-standards are provided by the Linux Standard Base.
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