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()