How can I execute an ant target depending on the value of an environment variable? - if-statement

Question

I want to execute an ant script on two different computers. Depending on the name of the computer either one of the two targets should be executed. Following doesn't work:
<project name="import" default="all">
<property environment="env"/>
<target name="staging" if="${env.COMPUTERNAME}='STG'">
<echo>executed on staging</echo>
</target>
<target name="production" if="${env.COMPUTERNAME}='PRD'">
<echo>executed on production</echo>
</target>
<target name="all" depends="staging,production" description="STG or PRD"/>
</project>
As I understood, "if" can only be used with property and it checks whether a property is set or not. But is there a way to to make a condition depending on the value of a property?

Answer 1

I would suggest writing an "init" target that sets any conditions you need for later build steps, and also fails the build if certain required properties don't evaluate to what's expected.
For example:
<target name="all" depends="staging,production,init" />
<target name="staging" if="staging.environment" depends="init">
<echo message="executed on staging" />
</target>
<target name="production" if="production.environment" depends="init">
<echo message="executed on production" />
</target>
<target name="init">
<condition property="staging.environment">
<equals arg1="${env.COMPUTERNAME}" arg2="STG" />
</condition>
<condition property="production.environment">
<equals arg1="${env.COMPUTERNAME}" arg2="PRD" />
</condition>
<fail message="Neither staging nor production environment detected">
<condition>
<not>
<or>
<isset property="staging.environment" />
<isset property="production.environment" />
</or>
</not>
</condition>
</fail>
</target>