Semaphores Libraries

#include<sys/types.h>
#include<sys/ipc.h>
#include<sys/sem.h>

int semget(key_t key, int nsems, int semflg);
int semctl(int semid, int semnum, int cmd, ...);
int semop(int semid, struct sembuf *sops, size_t nsops);

• semget() - returns the System V semaphore set identifier associated with the key argument.

• semctl() with cmd = SETVAL - Sets the value of semval to become arg.val for the semnum-th semaphore in the set.

• semctl() with cmd = IPC_RMID - removes the semaphore.

• semop() - performs operations on selected semaphores from the set designated by semid.