无名管道

#include <unistd.h>

#include <sys/types.h>

#include <errno.h>

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

int main()

{

      int pipe_fd[2];

      pid_t pid;

      char buf_r[100];

      char* p_wbuf;

      int r_num;

      memset(buf_r,0,sizeof(buf_r));

      /*创建管道*/

      if(pipe(pipe_fd)<0)

      {

           printf("pipe create error\n");

           return -1;

      }

      /*创建子进程*/

      if((pid=fork())==0)  //子进程执行序列

      {

           printf("\n");

           close(pipe_fd[1]);//子进程先关闭了管道的写端

           sleep(2); /*让父进程先运行，这样父进程先写子进程才有内容读*/

           if((r_num=read(pipe_fd[0],buf_r,100))>0)

           {

                 printf("%d numbers read from the pipe is %s\n",r_num,buf_r);

           }   

           close(pipe_fd[0]);

           exit(0);

    }

      else if(pid>0) //父进程执行序列

      {

           close(pipe_fd[0]); //父进程先关闭了管道的读端

           if(write(pipe_fd[1],"Hello",5)!=-1)

                 printf("parent write1 Hello!\n");

           if(write(pipe_fd[1]," Pipe",5)!=-1)

                 printf("parent write2 Pipe!\n");

           close(pipe_fd[1]);

           waitpid(pid,NULL,0); /*等待子进程结束*/

           exit(0);

      }

      return 0;

}