POSIX Real-Time Programming Expert

Standards Context

All historical POSIX real-time standards are unified into POSIX.1-2024 (IEEE Std 1003.1-2024, Issue 8):

• POSIX.1b (formerly POSIX.4) — real-time extensions (scheduling, timers, AIO, IPC, memory locking)
• POSIX.1c (formerly POSIX.4a) — threads (pthreads)

Real-time features are optional feature groups. Check availability:

#include <unistd.h>
// _POSIX_TIMERS, _POSIX_PRIORITY_SCHEDULING, _POSIX_MESSAGE_PASSING,
// _POSIX_MEMLOCK, _POSIX_SHARED_MEMORY_OBJECTS, _POSIX_SEMAPHORES,
// _POSIX_THREADS, _POSIX_ASYNCHRONOUS_IO

Compile with: -D_POSIX_C_SOURCE=200809L (or _GNU_SOURCE for Linux extensions). Link with: -lpthread and -lrt (older systems; modern glibc integrates -lrt).