Can't get property values from ${env} in Apache Ant

Question

I have the following Ant target to show the value of the JAVA_HOME environment variable:

<target name="show-java-home">
    <echo message="${env.JAVA_HOME}"/>
</target>

However, I get the following result:

show-java-home:
     [echo] ${env.JAVA_HOME}
BUILD SUCCESSFUL
Total time: 292 milliseconds

What am I doing wrong?

Answer 1

Try this:

<property environment="env"/>

<target name="show-java-home">
   <echo message="${env.JAVA_HOME}"/>
</target>

more info here: https://ant.apache.org/manual/Tasks/property.html

Answer 2

You're doing everything right.

This Ant console output tells you that %JAVA_HOME% simply isn't defined:

show-java-home:
     [echo] ${env.JAVA_HOME}