IPC 共享内存

#include<stdio.h>
#include<sys/ipc.h>
#include<sys/shm.h>
#define BUF_SIZE 1024
int main()
{
	int id = shmget(IPC_PRIVATE,BUF_SIZE,0666);
	if(id==-1)
	{
		perror("create shared memory fail");
	}
	system("ipcs -m");
	return 0;
}

#include<stdio.h>
#include<sys/types.h>
#include<sys/shm.h>
#include<stdlib.h>
int main(int args,char* argc[])
{	
	if(args<2)
	{
		puts("input the shmid!");
		exit(-1);
	}
	int shmid = atoi(argc[1]);
	char* addr = shmat(shmid,0,0);
	if(addr!=(void*)-1)
	{
		perror("shmat error");
	}
	system("ipcs");
	while(1);
	return 0;
}

#include<stdio.h>
#include<sys/types.h>
#include<sys/shm.h>
#include<stdlib.h>
int main(int args,char* argc[])
{	
	if(args<3)
	{
		puts("error!");
		exit(-1);
	}
	int shmid = atoi(argc[1]);
	int oper = atoi(argc[2]);
	char* addr = shmat(shmid,0,0);
	if(addr==(void*)-1)
	{
		perror("shmat error");
		exit(-1);
	}
	if(oper==1)  // write shared memory
	{
		scanf("%s",addr);	
	}
	else if(oper==2)  // read shared memory
	{
		printf("%s\n",addr);
	}	
	return 0;
}