Add $env function to JSONata expressions

red/runtime/util.js

@@ -359,6 +359,9 @@ function prepareJSONataExpression(value,node) {
     expr.assign('globalContext',function(val) {
         return node.context().global.get(val);
     });
+    expr.assign('env', function(val) {
+        return process.env[val];
+    })
     expr.registerFunction('clone', cloneMessage, '<(oa)-:o>');
     expr._legacyMode = /(^|[^a-zA-Z0-9_'"])msg([^a-zA-Z0-9_'"]|$)/.test(value);
     return expr;