title: How to read properties file using shell script
body: <p>How to read <code>config.properties</code> file using shell script?</p>
  
  <p>Example file:</p>
  
  <pre><code>key1 = This is 1st value
  
  key2 = this is 2nd value
  
  key3
  </code></pre>
  
  <ol>
  <li>Display all key and values.</li>
  <li>How to check which key don't have value?</li>
  <li>Enter any key that key related value display.</li>
  </ol>