title: Set Application_ENV via virtual host config and read this in PHP
body: <p>I like how this works in Zend Framework. I can know which environment I'm currently using by checking APPLICATION_ENV constant in my controller. </p>
  
  <pre><code>&lt;VirtualHost *:80&gt;
      #ServerName 
      #DocumentRoot
  
          SetEnv APPLICATION_ENV "development"
  
      # Directory
  &lt;/VirtualHost&gt;
  </code></pre>
  
  <p>But unfortunately I can't use ZF in my current project. How can I check this environment variable in my PHP code?</p>