title: Unable to read environment variables
body: <p>I have a simple Symfony project, using <code>"symfony/dotenv": "4.3.*",</code> in the <code>composer.json</code> and trying to read in the value of an environment variable.</p>
  
  <p>This is my command:</p>
  
  <pre><code>var_dump($_ENV['MY_NEW_VAR']);
  </code></pre>
  
  <p>This is my <code>.env</code> file</p>
  
  <pre><code>MY_NEW_VAR=testing
  </code></pre>
  
  <p>Upon executing the command I get the following</p>
  
  <pre><code>string(7) "testing"
  </code></pre>
  
  <p>All good so far.... But now if I want to use environment variables to override the setting it returns an error. First I set the environment variable</p>
  
  <pre><code>export MY_NEW_VAR="something_else"
  </code></pre>
  
  <p>Then execute the command again, with the following results</p>
  
  <pre><code>[ErrorException]
  Notice: Undefined index: MY_NEW_VAR
  </code></pre>
  
  <p>If I remove the environment variable using <code>unset MY_NEW_VAR</code> and execute the command again I get the value from the <code>.env</code> file</p>
  
  <p>I would expect the environment variable to override the <code>.env</code> setting as explained in the comments of the <code>.env</code> file</p>
  
  <pre class="lang-none prettyprint-override"><code># In all environments, the following files are loaded if they exist,
  # the later taking precedence over the former:
  #
  #  * .env                contains default values for the environment variables needed by the app
  #  * .env.local          uncommitted file with local overrides
  #  * .env.$APP_ENV       committed environment-specific defaults
  #  * .env.$APP_ENV.local uncommitted environment-specific overrides
  #
  # Real environment variables win over .env files.
  </code></pre>
  
  <p>Why does it not work with environment variables? Am I missing something?</p>