Portable Operating System Interface (POSIX)

POSIX, an acronym for "Portable Operating System Interface", is a family of standards specified by the IEEE for maintaining compatibility between operating systems. POSIX defines the application programming interface (API), along with command line shells and utility interfaces, for software compatibility with variants of Unix and other operating systems.

Acronym for Portable Operating System Interface for UNIX, a set of IEEE and ISO standards that define an interface between programs and operating systems. By designing their programs to conform to POSIX, developers have some assurance that their software can be easily ported to POSIX-compliant operating systems. This includes most varieties of UNIX.

POSIX is the Portable Operating System Interface, the open operating interface standard accepted world-wide. POSIX support assures code portability between systems and is increasingly mandated for commercial applications and government contracts. For instance, the USA's Joint Technical Architecture—Army (JTA-A) standards set specifies that conformance to the POSIX specification is critical to support software interoperability.