父子进程通过管道传递数据

#include <fcntl.h>#include <stdio.h>#include "apue.h"#include <errno.h>#include <sys/wait.h>#include <sys/types.h>#include <unistd.h>#include <stropts.h>#include <sys/mman.h>int main(int argc , char *argv[]){int n,fd[2];pid_t pid;char line[MAXLINE];if(pipe(fd)<0)err_sys("pipe err");if((pid=fork())<0)err_sys("pipe erro");else if(pid>0){close(fd[0]);if(write(fd[1],"hello world \n",13)<0)err_sys("write err");}else{close(fd[1]);if((n=read(fd[0],line,MAXLINE))<0)err_sys("read erro");if(write(STDOUT_FILENO,line,n)<0)err_sys("write erro");}exit(0);}