@@ -6,6 +6,7 @@

 import logging

 from logging import debug, info, warning, error

 import re

+import os

 import Progress

 from SortedDict import SortedDict

@@ -116,6 +117,9 @@ class Config(object):

     def update_option(self, option, value):

         if value is None:

             return

+        #### Handle environment reference

+        if str(value).startswith("$"):

+            return self.update_option(option, os.getenv(str(value)[1:]))

         #### Special treatment of some options

         ## verbosity must be known to "logging" module

         if option == "verbosity":