title: Check if a file exists with puppet template
body: <p>I try to check if a file exists on client who run puppet agent.
  On my puppet master, I have a template.erb like this :</p>
  
  <pre><code>&lt;% if File.exists?('/usr/bin/lwp-request') %&gt;SCRIPTWHITELIST="/usr/bin/lwp-request"&lt;% end %&gt;
  </code></pre>
  
  <p>This little code in my template is needed to my rkhunter module.
  The result is always false, however the file exists.</p>
  
  <p>If I add the file on the puppet master, the result is true. So the ruby code seems to be executed on the master.</p>
  
  <p>How can I check on my template if a file exists on client ?</p>
  
  <p>Tested on puppet 2.7.5 and 2.8.1.</p>
  
  <p>Thanks</p>