title: Pass environment variables to Hive Transform or MapReduce
body: <p>I am trying to pass a custom environment variable to an executable (my-mapper.script in the example below) used in a Hive Transform
  eg:</p>
  
  <pre><code>SELECT
     TRANSFORM(x, y, z)
     USING 'my-mapper.script'
  FROM
  (
     SELECT
        x, y, z
     FROM
        table
  )
  </code></pre>
  
  <p>I know in Hadoop streaming this can be achieved using </p>
  
  <pre><code>-cmdenv EXAMPLE_DIR=/home/example/dictionaries/
  </code></pre>
  
  <p>But I do not know how to do this in a Hive Transform/MapReduce.</p>
  
  <p>Any ideas?</p>