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Creation: June 02 2016
Modified: February 05 2022

do one thing and do it well

UNIX Historical Notes

UNIX is a family of operating systems that derive from the original AT&T UNIX, developed in the 1970s at the Bell Labs research center by Ken Thompson and Dennis Ritchie. Actually the UNIX trademark passed to the industry standards consortium The Open Group, which allows the use of the mark for certified operating systems compliant with the Single UNIX Specification.

Portable Operating System Interface (POSIX)

POSIX is a family of standards specified by the IEEE for maintaining compability between operating systems. POSIX defines the API, command line shells and utility interfaces.

The name POSIX was coined by Richard Stallman the founder of the Free Software Foundation.

Single UNIX Specification (SUS)

SUS is a superset of the POSIX.1 standard. Also sets some POSIX optional interface groups as mandatory. Was a publication of The Open Group, founded in 1996 as a merge of X/Open and The Open Software Foundation. Actually is maintained by the Austin Group.

The specification became more popular because it was available at no cost, whereas the IEEE charged a substantial fee for access the POSIX specification.

C Language

The origin of the language is closely tied to the development of UNIX. Originally implemented in assembly language on a PDP-7 by Dennis Ritchie and Ken Thompson and used in the re-implementation of the research UNIX.

UNIX Systems

AT&T System V

Originally developed by AT&T. Four major versions of System V were released numbered 1, 2, 3, and 4. The release 4 (SVR4) was the most successfull version, being the result of an effort marked as "UNIX System Unification".

The System V Interface definition (SVID) is a standard that describes the System V behaviour, including system calls, C libraries, available programs and devices.

Barkley Software Distribution

Developed and distributed by the Computer Research Group of the University of California Barkley from 1977 and 1995. Shared the initial codebase and design with the original AT&T UNIX operating system.


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