System V IPC vs POSIX IPC

Question

1. What are the differences between System V IPC and POSIX IPC ?
2. Why do we have two standards ?
3. How to decide which IPC functi

Answer 1

1. I believe the major difference is that all POSIX IPC is thread-safe, while most SysV IPC is NOT [1].
2. Because of Unix wars [2]. The Single UNIX specification (SUS) [3], aka POSIX, was created to standardise interfaces on Unix-based systems.
3. You probably want POSIX. Depends exclusively on your requirements.