title: Read values from configuration file and use in shell script
body: <p>I have a text configuration file something like this :</p>
  
  <pre><code>## COMMENT
  KEY1=VALUE1  ## COMMENT
  KEY2=VALUE2
  
  KEY3=VALUE3  ## COMMENT
  
  ## COMMENT
  </code></pre>
  
  <p>As you can see, this has key value pairs, however it also contains comment lines and blank lines. In some cases, the comments are on the same line as the key value pair. </p>
  
  <p>How do I read this config file and set the keys as variable names in a shell script so that I can use them as :</p>
  
  <pre><code>echo $KEY1 
  </code></pre>