Cannot redirect output when I run Python script on

Question

This is running on Windows 7 (64 bit), Python 2.6 with Win32 Extensions for Python.

I have a simple script that just print "hello world". I can launch it with python hello.py. In this case I can redirect the output to a file. But if I run it by just typing hello.py on the command line and redirect the output, I get an exception.

C:> python hello.py
hello world

C:> python hello.py >output

C:> type output
hello world

C:> hello.py
hello world

C:> hello.py >output
close failed in file object destructor:
Error in sys.excepthook:

Original exception was:

I think I first get this error after upgrading to Windows 7. I remember it should work in XP. I have seen people talking about this bug python-Bugs-1012692 | Can't pipe input to a python program. But that was long time ago. And it does not mention any solution.

Have anyone experienced this? Anyone can help?

Answer 1

UPDATED ANSWER

A Microsoft KB issue (STDIN/STDOUT Redirection May Not Work If Started from a File Association) may be exactly this issue. The page has instructions for downloading a Win2000 hotfix, but that might not be needed on more recent Windows versions. After the hotfix (or possibly without it, depending on your Win version), a manual registry edit is needed.

You should check the link I provided; in any case, I summarize here:

• Open Registry Editor and locate the key HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
• Add a DWORD value named InheritConsoleHandles and set it to 1.

That's it, supposedly.

Answer 2

I am not aware of the issue, but I have an idea to work around it. Have you thought about adding a command-line option (like -o) to specify an output file that will capture the output?

Answer 3

Are you asking about this?

Windows: When executing Python scripts on the command line using file type associations (i.e. starting "script.py" instead of "python script.py"), redirects may not work unless you set a specific registry key. See the Knowledge Base article STDIN/STDOUT Redirection May Not Work If Started from a File Association.

It's in the Python README. Perhaps this patch is what you're looking for.

Answer 4

If you are trying to redirect stdout and stderr from the command prompt, see http://support.microsoft.com/kb/110930