import os  print 'setenv...',  print os.environ['USER']                 # show current shell variable value    os.environ['USER'] = 'Brian'             # runs os.putenv behind the scenes  os.system('python echoenv.py')    os.environ['USER'] = 'Arthur'            # changes passed to spawned programs  os.system('python echoenv.py')           # and linked-in C library modules    os.environ['USER'] = raw_input('?')      print os.popen('python echoenv.py').read()