title: Bash: Format environment variables in string
body: <p>How does one format a string leveraging an environment variable within at the command line? For example, I want to curl and pass some variable, i.e.:</p>
  
  <pre><code>curl -X POST --data-urlencode 'payload={"text": "I want to print an environment variable here, eg a path: $PATH"}' https://someapi.com/
  </code></pre>