title: Jenkins. Inserting environment variable in the file
body: <p>I have a <code>.env</code> file that contains the following data </p>
  <pre><code>API_URL=${API_URL}
  API_KEY=${API_KEY}
  API_SECRET=${API_SECRET}
  </code></pre>
  <p>Setting environment variables in Jenkins and passing them to the pipeline is clear. But it is not clear how do I replace ${API_URL}, ${API_KEY} &amp; ${API_SECRET} in the <code>.env</code> file with their values in the Jenkins environment variable? Plus, how do I loop through all the Jenkins variables?</p>