Is java an option?
Create a named java-bean and access the system variable via expression
example:
{#myJava.getMySystemVars(someParameter - typically execution variable from process)}
example from Oracle:
and in method getMySystemVars -
System.getProperty(“path.separator”);
I haven’t had the need to read system properties in a while - typically reading from application properties… So, this is just an example from Oracle’s java ref’