Python setting environment variables for processes

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() </pre>