>>> from tempfile import mkstemp
>>> t = mkstemp('.pgp', 'mobil-', '/tmp/')
>>> t
(3, '/tmp/mobil-DPDNbn.pgp')
>>> import os
>>> os.fdopen(t[0])
<open file '<fdopen>', mode 'r' at 0xb7e40960>
>>> fp = os.fdopen(t[0])
>>> fp.write('test message\n')
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
IOError: [Errno 9] Bad file descriptor