int pipe1[2], pipe2[2], pipe3[2];
  pid_t pid;

  char string1[1000], string2[1000];

  if (pipe(pipe1) == -1)
  {
    perror("demo1");
    exit(1);
  }
  if ((pid = fork()) == -1)
  {
    perror("demo2");
    exit(1);
  }
  else if (pid == 0)
  {
    close(pipe1[0]);       // close read end of pipe
    dup2(pipe1[1], 1);     // make 1 same as write-to end of pipe
    close(pipe1[1]);       // close excess fildes
    execvp(cmd1[0], cmd1); // execute
    perror("demo3");       // still around?  exec failed
    _exit(1);              // no flush
  }
  if (pipe(pipe2) == -1)
  {
    perror("demo4");
    exit(1);
  }
  if ((pid = fork()) == -1)
  {
    perror("demo5");
    exit(1);
  }
  else if (pid == 0)
  {
    close(pipe2[1]);
    dup2(pipe2[0], 0);
    execvp(cmd2[0], cmd2);
    close(pipe2[0]);
    perror("demo6");
    _exit(1);
  }

  if (pipe(pipe3) == -1)
  {
    perror("demo7");
    exit(1);
  }
  if ((pid = fork()) == -1)
  {
    perror("demo8");
    exit(1);
  }
  else if (pid == 0)
  {
    close(pipe3[1]);
    dup2(pipe3[0], 0);
    execvp(cmd3[0], cmd3);
    close(pipe3[0]);
    perror("demo9");
    _exit(1);
  }

  if (pid > 0)
  {
    /*
    Read from pipe 1
    */
    close(pipe1[1]);   //close write end of pipe
    dup2(pipe1[0], 0); // make 0 same as read-from end of pipe
    int string1_length = read(pipe1[0], string1, 1000);
    close(pipe1[0]);

    /*
    Write to pipe 2
    */
    dup2(pipe2[1], 1);
    close(pipe2[1]);

    /*
    Write to pipe 3
    */
    dup2(pipe3[1], 1);
    close(pipe3[1]);
    perror("demo10");
    exit(1);
  }
  return 0;