Except that Unix also allows &quot;-&quot; in the filename, and as far as I know always has done. Using &quot;--&quot; to mark that all subsequent arguments should be treated as filenames rather than options has worked fine to allow Unix programs to access files beginning with a dash (including files called &quot;--&quot;).<p>The actual reason that DOS uses &quot;&#x2F;&quot; to mark options isn&#x27;t technical, it&#x27;s purely historic: that was the character that CP&#x2F;M used.