POSIXs

POSIX stands for the Portable Operating System Interface. It is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines the application programming interface (API), along with callable services, utility programs and file format, for software development. The primary goal of POSIX is to promote portability of applications across different operating systems.

The POSIX standards are based on UNIX. While POSIX is not a specification of UNIX itself, it describes the common features of UNIX operating systems. Many operating systems, including Linux, macOS, and various BSD derivatives, comply with POSIX standards, allowing software written for one POSIX-compliant system to be compiled and run on another with minimal or no modification. This is particularly important for software intended for server environments or high-performance computing where cross-platform compatibility is crucial.

Key aspects defined by POSIX include file system structure, process management, inter-process communication, and the C programming language interface. The standards are organized into different parts, such as POSIX.1 (Core Services), POSIX.2 (Utilities and Shells), and others covering real-time extensions and threading. Adherence to POSIX helps ensure that applications can be developed once and deployed on a wide range of compatible systems, simplifying development and maintenance efforts.