1.4.。

无名

#include 

int main(int argc, const char *argv[])
{
	int fd[2];
	if(pipe(fd)){
		perror("pipe error");
		return -1;
	}

	pid_t pid = fork();
	if(pid == 0){
		close(fd[0]);
		char buf[] = "hello world\n";
		while(1){
			write(fd[1], buf, sizeof(buf));
			sleep(1);
		}
	}else if(pid >0){
		close(fd[1]);
		char buf[32] = "";
		while(1){
			read(fd[0], buf, sizeof(buf));
			printf("%s", buf);
		}
	
	}else{
		perror("fork error");
		return -1;
	}
	return 0;
}

信号

#include 

int main(int argc, const char *argv[])
{
	pid_t pid = fork();
	if(pid == 0){
		while(1){	
			puts("hello");
			sleep(1);
		}
	}else if(pid >0){
		sleep(5);
		kill(pid, SIGKILL);
		puts("over");
	}else{
		perror("fork error");
		return -1;
	}
	return 0;
}

消息队列

#include 

typedef struct msgbuf{
	long mtype;
	char mtext[32];
}msg_t;

int main(int argc, const char *argv[])
{
	key_t key = ftok("./", 'k');
	if(key == -1){
		perror("ftok error");
		return -1;
	}

	int msgid = msgget(key, IPC_CREAT|0664);
	if(msgid == -1){
		perror("msgget error");
		return -1;
	}
	
	msg_t msg = {1, "hello"};
	while(1){
		msgsnd(msgid, &msg, sizeof(msg), 0);
		sleep(1);
	}
	return 0;
}