Use sem_destroy(3RT) to destroy any state that is associated with the unnamed semaphore pointed to by sem.
int sem_destroy(sem_t *sem);
#include <semaphore.h> sem_t sem; int ret; ret = sem_destroy(&sem); /* the semaphore is destroyed */
The space for storing the semaphore is not freed.
sem_destroy() returns zero after completing successfully. Any other return value indicates that an error occurred. When the following condition occurs, the function fails and returns the corresponding value.
EINVAL
Description:sem points to an illegal address.