title: Is there any established order for 'ls' arguments?
body: <p>I'm a student and as part of my cursus I must recode the <code>ls</code>command and reproduce its behaviour the best possible.</p>
  
  <p>On Mac (El Capitan 10.11.6), using the terminal iTerm 2(zsh), I get:</p>
  
  <pre><code>user&gt; ls . -R
  ls: -R: No such file or directory
  </code></pre>
  
  <p>And on Arch (latest version), using the default text interface(bash) I get:</p>
  
  <pre><code>user&gt; ls . -R
  &lt;current directory content&gt;
  </code></pre>
  
  <p>Although I'd rather trust Arch, is it correct for ls to refuse its option after a directory has been specified ? And is there any documentation declaring the arguments order ?</p>