title: How a session variable in php multi domain?
body: <p>I have a dedicated server with 3 website on: </p>
  
  <p>www / </p>
  
  <p>   www / site1 (www.site1.com)</p>
  
  <p>   www / site2 (www.site2.com) </p>
  
  <p>   www / site3 (www.site3.com)</p>
  
  <p>I am that if a session is created either on site1, site2 website or 3 it is made available to the other two, for example in the context of authentication. </p>
  
  <p>Site1: => Member 1  => Log ok, create the session id </p>
  
  <pre><code>&lt;?php 
  $ _SESSION ['Id'] = $user-&gt; id; 
  echo $ _SESSION ['id']; // Returns 1 
  ?&gt;
  </code></pre>
  
  <p>I need regular.> </p>
  
  <p>And as on site2 and website 3. </p>