title: how to create global variable in cakephp 3.4
body: <p>I'm working in CakePHP 3.4 and want to create a global variable to store 
  some information that can be used throughout the application.   </p>
  
  <p>I have tried this code 
  in <code>s.ctp</code> which is first controller that I am writing </p>
  
  <pre><code> &lt;?php
   namespace App\Controller;
   use Cake\Controller\Controller;
   use Cake\Event\Event;
   use Cake\Core\Configure;
  
   Configure::write('variable_name', 'Some Value');
    ?&gt;
  </code></pre>
  
  <p>and getting this global variable in <code>p.ctp</code> where my code is </p>
  
  <pre><code> &lt;?php 
   namespace App\Controller;
   use Cake\Controller\Controller;
   use Cake\Event\Event;
   use Cake\Core\Configure;
  
  echo Configure::read('variable_name');
   ?&gt;
  </code></pre>
  
  <p>but nothing is shown in <code>echo</code> what am I doing wrong?</p>