title: PIG_HOME environment variable in a pig latin script
body: <p>I would like to access the $PIG_HOME environment variable from within a pig latin script.</p>
  
  <p>I want something like this (doesn't work):</p>
  
  <pre><code>register $PIG_HOME/contrib/piggybank/java/piggybank.jar
  </code></pre>
  
  <p>instead of hardcoding like this (works):</p>
  
  <pre><code>register /home/user/opt/pig-0.11.1/contrib/piggybank/java/piggybank.jar
  </code></pre>