...
See the <packs> element documentation for more information on how to use the <parsable> tag.
Using System Properties As Variables
System properties given on the command line can be directly included as IzPack variables when using the SYSTEM_ prefix followed by the system property name in the variable name, and substituting alls occurences of '.' by '_'. System properties with null values are not substituted.
Examples:
$SYSTEM_java_version$SYSTEM_os_name