title: Maven read environment variable in properties file
body: <p>How to read system environment variables in a properties file. I am using MyBatis maven plugin for database migrations. MyBatis use properties file basing on the environment. I am trying to read environment variable inside properties file like: </p>
  
  <p><strong>development.properties</strong></p>
  
  <pre><code>username=${env.username}
  password=${env.password}
  
  Error: FATAL: role "${env.username}" does not exist
  </code></pre>
  
  <p>I stored username and password in a ".profile" file on a mac. What's the correct way to read those variables?</p>