[Python-Dev] PEP 389: argparse - new command line parsing module (original) (raw)

Hrvoje Niksic hrvoje.niksic at avl.com
Wed Oct 7 13:26:59 CEST 2009

Paul Moore wrote:

Traceback (most recent call last): File "hello.py", line 13, in main() File "hello.py", line 7, in main sys.stdout.flush() IOError: [Errno 9] Bad file descriptor

(Question - is it ever possible for a Unix program to have invalid file descriptors 0,1 and 2? At startup - I'm assuming anyone who does os.close(1) knows what they are doing!)

Of course; simply use the >&- pseudo-redirection, which has been a standard sh feature (later inherited by ksh and bash, but not csh) for ~30 years. The error message is amusing, too:

$ python -c 'print "foo"' >&- close failed in file object destructor: Error in sys.excepthook:

Original exception was:

Adding an explicit flush results in a more understandable error message:

Traceback (most recent call last): File "", line 1, in IOError: [Errno 9] Bad file descriptor

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