• Stands for Portable Operating System Interface

  • A set of standards designed by IEEE for Library Call, specifying the interface between Kernel and OS System Program. This ensures compatibility and portability of applications across different Unix-like operating systems (Linux Kernel, macOS, BSD, etc

  • Implements a set of automated conformance test to check if a kernel is POSIX-compatible

  • Defines Standard C operations, Multi-tasking and commands etc

  • Has about 100 Library Call, but not one-to-one mapping to System Call (系统调用). Below is a list of major POSIX system calls

Write Once, Run (Mostly) Anywhere

A POSIX-compliant application written using the standard system calls should be source-code compatible across different POSIX-compliant operating systems. This massively reduces the development effort for cross-platform software.

System Vendors Get Guidance

Operating system vendors have a blueprint for the set of system calls that should ideally be implemented in their systems for better standardization