POSIX

POSIX = (Portable Operating System Interface)

POSIX (Portable Operating System Interface) is a set of standard operating system interfaces based on the Unix operating system.

Conjunto de interfaces estándares para sistemas operativos, basados en el sistema operativo UNIX.
POSIX.1 - Estándar API en C
POSIX.2 - Shell
POSIX.4 - Threads