将一个子进程的输出作为另一子进程的输入

Question

I'm trying to run ls -l with sort so sort can be applied to ls -l
but when i run it it doesn't give the same output as ls -l | sort I'm not sure why I understand piping,dupe,fork,close somewhat but still confused on how to apply them to make this work

  int pipe1[2];
  // will hold the ids of our forks
  pid_t pid1;
  // will hold the ids of our forks
  pid_t pid2;

  pipe(pipe1);

  // call our child process
  pid1 = fork();

  if (pid1 == 0)
  {
    // dealocate the 1 of
    close(1);
    // duplicate the write end
    dup(pipe1[1]);
    // close the read end
    close(pipe1[0]);
    // close the write end
    close(pipe1[1]);

    printf("child1 executing ls \n");
    execl("/bin/ls", "ls", 0, 0);
    perror("execl error");
  }
  else
  {
    wait(&pid1);

    pid2 = fork();

    if (pid2 == 0)
    {
      close(0);
      dup(pipe1[0]);
      close(pipe1[0]);
      close(pipe1[1]);

      printf("child2 executing sort \n");
      execl("/bin/sort", "sort",0, 0);
      perror("execl error");
    }
    else
    {
      wait(0); //wait for children
    }
  }
}

Answer 1

add below into else { [here] wait(0); }

close(pipe1[0]);
close(pipe1[1]) ;