Someone

 #include <stdio.h>    #include <stdlib.h>    #include <errno.h>    #include <sys/types.h>    #include <sys/ipc.h>    #include <sys/sem.h>    int main(void)    {        key_t key;        int semid;               key = ftok("writer.c", 'J');	semid = semget(key,2,IPC_CREAT | 0600);	semctl(semid,0,SETVAL,1);	semctl(semid,1,SETVAL,1);int i;for(i = 0; i<5; i++){semctl(semid,0,SETVAL,0);semctl(semid,1,SETVAL,0);printf("Writing\n");sleep(4);printf("done\n");semctl(semid,0,SETVAL,1);semctl(semid,1,SETVAL,1);sleep(8);}        return 0;    }