#include <mqueue.h> 
 
mqd_t mq_send(mqd_t mqdes, const char *msg_ptr, 
              size_t msg_len, unsigned msg_prio); 
 
#define _XOPEN_SOURCE 600 
#include <time.h> 
#include <mqueue.h> 
 
mqd_t mq_timedsend(mqd_t mqdes, const char *msg_ptr, 
              size_t msg_len, unsigned msg_prio, 
              const struct timespec *abs_timeout); 
 
-lrt를 링크해야 한다. 
 

struct timespec { 
    time_t tv_sec;        /* seconds */ 
    long   tv_nsec;       /* nanoseconds */ 
};