title: Replacing a word with $ in groovy
body: <p>I have the following piece of groovy code from a gradle build file I am using for replacing a word in a php file: </p>
  
  <pre><code>def str1="My application version is $app_version" 
  def str2 = str1.replaceAll('$app_version','2016072601')
  println str2​
  </code></pre>
  
  <p>I want to replace $app_version with defined number in this method but somehow it is not working. Do I need to escape or do any special action to perform this replacement? </p>