title: Jenkins workflow pass variable to shell script
body: <p>How can I pass a variable e.g. <code>buildNumber</code></p>
  
  <pre><code>sh 'gulp sometask --someOption="attribute=${env.BUILD_NUMBER}"'
  </code></pre>
  
  <p>to the <code>sh</code> command using Jenkins workflow / pipeline?
  My example unfortunately only yields a bad substitution error.</p>