title: change file extension with a ruby script
body: <p>I'm trying to change the exstension of a file passing the arguments by console</p>
  
  <pre><code>system = "rename" , "'s/\#{ARGV[0]}$/\#{ARGV[1]}'", "*#{ARGV[1]}"
  </code></pre>
  
  <p>The code is correct because it works on console but when I put it in a script I have trouble with </p>
  
  <pre><code>s/\#
  </code></pre>
  
  <p>because it appears in pink and the console does not get it.</p>