Cannot redirect output when I run Python script on Windows using just script's name

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?

Are you aware that there are TWO output streams: stdout and stderr? — S.Lott, Jun 10 '10 at 23:04

score 20 · Accepted Answer · edited Mar 16 '17 at 10:34

20

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.

edited Mar 16 '17 at 10:34

Alexander

23,432
11
63
73

answered Jun 11 '10 at 20:43

S.Lott

384,516
81
508
779

1

That's it. Just adding the InheritConsoleHandles registry value does it! Thanks a ton!!! – Wai Yip Tung Jun 11 '10 at 21:45
1

The link to the article is now dead. Here is an archive of the page: https://web.archive.org/web/20150403070207/http://support.microsoft.com/en-us/kb/321788 Edit: According to the latest version of that page, the issue was fixed in a service pack for Windows XP. – Arthur Tacca Jan 30 '19 at 08:01

tzot · Answer 2 · 2010-06-11T22:24:02.403

8

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.

edited Jun 11 '10 at 22:24

answered Jun 11 '10 at 09:54

tzot

92,761
29
141
204

I do have it in the PATHEXT. That's how I usually run the script. Unfortunately I got the same error with or without entering the .py extension. – Wai Yip Tung Jun 11 '10 at 18:11
@Wai: check the “new and improved” version of my answer, and let me know if this works for you. – tzot Jun 11 '10 at 22:24
Oops. Didn't see that S.Lott had already provided the same link. Sorry :) – tzot Jun 11 '10 at 22:25
Yes, that was the issue. Thanks. It helped a lot! – Wai Yip Tung Jun 11 '10 at 22:50

score 1 · Answer 3 · answered May 02 '13 at 13:58

1

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

answered May 02 '13 at 13:58

Bed

11
1

score 0 · Answer 4 · answered Jun 10 '10 at 22:00

0

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?

answered Jun 10 '10 at 22:00

jathanism

33,067
9
68
86

Thanks for your suggestion. This will do as a last resort :) But it is not as effortless as just typing ">output" on demand. Plus I have a lot of scripts and it is not practical to change all of them. – Wai Yip Tung Jun 10 '10 at 22:10

Cannot redirect output when I run Python script on Windows using just script's name

4 Answers4

Linked

Related