ANT: how to append some text to a file

• To append plain text:
  

  <echo file="file.txt" append="true">Hello World</echo>

• To append HTML or XML, you need escape it using CDATA:
  

  <echo file="file.txt" append="true">
  <![CDATA[
    <h1>Hello World</h1>
  ]]>
  </echo>