main.c~

linux terminal thread semophores

#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <stdio.h>
#include <string.h>
#include <sys/shm.h>
#include <sys/wait.h>

int main()
{
  struct shmid_ds buf;
  int a[10]={0,1,2,3,4,5,6,7,8,9};
  int a1[10]={0,0,0,0,0,0,0,0,0,0};
  pid_t pid;
  key_t key;
  int shmid; 
  int *p,ps,i;
  if((key = ftok("./",'a'))==-1){
	perror("key");
	return -1;

  }

  if((shmid = shmget(key,30*sizeof(int),IPC_CREAT|0640))==-1){
	perror("shmget");
	return -1;
  }
  if((p=(int *)shmat(shmid,NULL,0))==(void *)-1){
	perror("shmat");
	return -1;
  }
  pid=fork();
  switch(pid){
     	case -1:
		perror("fork");
		return -1;
	case 0:
		memcpy(p,a,sizeof(a));
		sleep(2);
		a1[0]=getpid();
		memcpy(p,a1,sizeof(a1));
		while(1);
		break;
	default:
		while(waitpid(pid,&ps,WNOHANG)==0){
			for(i=0;i<sizeof(a)/sizeof(int);i++)
				printf("%d  ",p[i]);
			usleep(500000);
			if(p[0]>0)
				kill(p[0],9);
		}
		printf("\n");
		
		shmdt(p);		
		if(shmctl(shmid,IPC_RMID,&buf)==-1){
			perror("shmclt");
			return -1;
		}
  }
return 0;
}