linux pipe

pipe.c

#include <unistd.h>
#include <sys/types.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>

#define MAX_DATA_LEN 256
#define DELAY_TIME 1

int main(){
	pid_t pid;
	int pipe_fd[2];
	char buf[MAX_DATA_LEN];
	const char data[] = "pipe test";
	int real_read, real_write;

	memset((void *)buf, 0, sizeof(buf));

	/* 创建管道*/
	if(pipe(pipe_fd) < 0){
		printf("pipe create error\n");
		exit(1);
	}

	if((pid = fork()) == 0 ) {
		close(pipe_fd[1]);
		/*子进程关闭写描述符*/
		sleep(DELAY_TIME * 3);
		if ((real_read = read(pipe_fd[0], buf, MAX_DATA_LEN)) >0) {
			printf("%d bytes read from the pipe is '%s'\n", real_read, buf);
		}
		close(pipe_fd[0]);
		exit(0);
	}
	else if (pid >0) {
		/* 关闭父进程读描述符 */
		close(pipe_fd[0]);
		sleep(DELAY_TIME);

		if ((real_write = write(pipe_fd[1], data, strlen(data))) != -1) {
			printf("parent wrote %d bytes:'%s'\n", real_write, data);
		}

		close(pipe_fd[1]);

		waitpid(pid, NULL, 0);
		exit(0);
	}
}