1 globals().update(os.environ)  # Import environment
   2 
   3 
   4 def replace_w_global_value(mo):
   5     key = mo.group(0)
   6     without_dollar = key[1:]
   7     return str(globals().get(without_dollar, key))
   8 
   9 
  10 def subs(input):
  11     """Perform Bash-like substitutions.
  12 
  13     Any "$FOO" in a string will be replaced with the value of FOO.
  14     If it's not defined, it stays as it was: "$FOO".
  15     """
  16     return re.sub('[$][A-Za-z_]+', replace_w_global_value, input)