access to environment variables in solrconfig.xml and/or schema.xml?

[Burton-West, Tom]

I see variables used to access java system properties in solrconfig.xml and 
schema.xml:

http://wiki.apache.org/solr/SolrConfigXml#System_property_substitution
<dataDir>${solr.data.dir:}</dataDir>
or
${solr.abortOnConfigurationError:true}

Is there a way to access environment variables or does everything have to be 
stuffed into a java system property?

Tom Burton-West