linux pipeの試み(一)

#include <stdio.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/types.h>
int main()
{
  int pipefd[2];
  int pfd = pipe(pipefd);
  char buf[20];
  int ffd = fork();
  memset(buf,0,sizeof(buf));
  if(ffd>0)
  {
    close(pipefd[0]);
    sleep(5);
    write(pipefd[1],"hello",sizeof("hello"));
    printf("write finished
");
    close(pipefd[1]);
//    wait(NULL);
  }
  else
  {
    close(pipefd[1]);
//    sleep(5);
    read(pipefd[0],buf,sizeof(buf));
    printf("read over
");
    close(pipefd[0]);
  }
  printf("buf:%s,pid=%d,ppid=%d
",buf,getpid(),getppid());
  sleep(2);
  return 0;

}
 



 
                     
     ，read     ，              。