title: escaped filename slashes
body: <p>I want to generate filename from a user-inputed string and to make sure that it is safely escaped.</p>
  
  <p>for example, if the user enters <code>/usr/bash</code> the output will be <code>\/usr\/bash</code>
  and if the input is <code>The great theater</code> the output is <code>The\ great\ theater</code>.</p>