Ant

Apache Ant is a Java-based build tool.

Define a variable

<!-- Declare the variable(e.g Assign a number to PI variable). -->
<property name="PI" value="3.1415"/>
 
<!-- Using the variable(e.g echo the value of pi). -->
<echo message="${PI}"/>

Build in properties: http://ant.apache.org/manual/using.html#built-in-props

Core tasks: http://ant.apache.org/manual/coretasklist.html