Question

Hi I am using ant to build a scala android project. It seems my ${scala_home} does not expand and I have to hard code the scala location. I obviously dont want to do this.

Any thoughts on what I may be doing incorrectly. It looks like no env variables are expanded in the script. I have tested this with < echo message=”${PATH}” / > and ${PATH}

Answer 1

Environment variables are not automatically available to be referenced as properties within an Ant build.

Two options for passing an environment variable to Ant:

• Supply the variable on the Ant command line as a property definition
• Set a prefix to be used to access environment variables via properties

For the first you might use:

$ ant -Dscala_home=$SCALA_HOME

Which would make set the scala_home property for the build.

For the second you might use:

<property environment="env" />

to specify the prefix, then you can see the value in this way:

<echo message="${env.SCALA_HOME}" />

If you somehow have a complex build.xml that relies on an un-prefixed property – ${scala_home} – then you could copy the value over from the environment using

<property environment="env" />
<property name="scala_home" value="${env.scala_home}" />

(Note that you may need to adjust case in environment variable names.)