#include <stdio.h>#include <sys/ipc.h>#include <sys/shm.h>int main(void){	key_t key;	int shmid;	int proj_id;	key=IPC_PRIVATE;	shmid=shmget(key,1024,0660);	if(shmid==-1)		perror("cannot create a shared memory segment");	else		printf("1. key=IPC_PRIVATE, shared memory segment shmid= %d\n",shmid);	proj_id=1;	key=ftok("/home/program",proj_id);	if(key==-1)		perror("cannot generate IPC key");	shmid=shmget(key,1024,IPC_CREAT|0660);        if(shmid==-1)                perror("cannot create a shared memory segment");	else        	printf("2. key=%d generated by ftok, shared memory shmid= %d\n",key,shmid);		shmid=shmget(key,1024,IPC_CREAT |IPC_EXCL |0660);	if(shmid==-1)		perror("cannot create a shared memory segment");	shmid=shmget(key,1024,IPC_CREAT |0660);	if(shmid==-1)		perror("cannot create a shared memory segment");		else		printf("Access the existing shared memory segment\n");	return 0;}