说明：  ls 命令可以说是linux下最常用的命令之一。它有众多的选项，其中有很多是很有用的，你是否熟悉呢？我写了一个模拟ls命令的程序,非常有用.
(ls command can be said to be under linux, one of the most commonly used commands. It has a large number of options, many of whom are very useful, are you familiar with it? I wrote a simulated ls command procedures, very useful.)