title: Using altered %{REQUEST_URI} in RewriteCond file exists check
body: <p>I'm wanting to take a URL such as <a href="http://localhost/universe/networks/o2/o2_logo.gif" rel="noreferrer">http://localhost/universe/networks/o2/o2_logo.gif</a> and do the following:</p>
  
  <pre>
  If it begins with /universe/
  Strip /universe/ from it to become /networks/o2/o2_logo.gif
  Check if this exists in %{DOCUMENT_ROOT}/networks/o2/o2_logo.gif
  If so, silently rewrite the request to this file.
  </pre>
  
  <p>If I use a rule of:</p>
  
  <pre>
  RewriteCond %{REQUEST_URI} ^/universe/
  RewriteRule ^(.*)$ http://www.example.org/$1 [L]
  </pre>
  
  <p><a href="http://localhost/universe/networks/o2/o2_logo.gif" rel="noreferrer">http://localhost/universe/networks/o2/o2_logo.gif</a> gets re-written to <a href="http://www.example.org/networks/o2/o2_logo.gif" rel="noreferrer">http://www.example.org/networks/o2/o2_logo.gif</a> which is great, but I can't seem to use the </p>
  
  <p>How can I go about using this 'changed' %{REQUEST_URI} further down as say $1 or something?</p>