title: Regular Expression usage with ls
body: <p>I am trying to use ER <em>(Extended Regular Expressions)</em> with <code>ls</code> like <code>ls .+\..+</code>.</p>
  
  <p>I am trying to print all files which contains an extension 
  (I know I could have used <code>ls *.*</code>, but I wanted to try using ER).</p>
  
  <p>When I run that code I get this error: <code>ls: .+..+: No such file or directory</code>. </p>