Windows is not passing command line arguments to Python programs executed from the shell

I'm having trouble getting command line arguments passed to Python programs if I try to execute them directly as executable commands from a Windows command shell. For example, if I have this program (test.py):

import sys
print "Args: %r" % sys.argv[1:]

And execute:

>test foo
Args: []

as compared to:

>python test.py foo
Args: ['foo']

My 开发者_开发技巧configuration has:

PATH=...;C:\python25;...
PATHEXT=...;.PY;....

>assoc .py
.py=Python.File

>ftype | grep Python
Python.CompiledFile="C:\Python25\python.exe" "%1" %*
Python.File="C:\Python25\python.exe" "%1" %*
Python.NoConFile="C:\Python25\pythonw.exe" "%1" %*

I think I solved this. For some reason there is a SECOND place in the registry (besides that shown by the file associations stored in HKEY_CLASSES_ROOT\Python.File\shell\open\command):

[HKEY_CLASSES_ROOT\Applications\python.exe\shell\open\command]
@="\"C:\\Python25\\python.exe\" \"%1\" %*"

This seems to be the controlling setting on my system. The registry setting above adds the "%*" to pass all arguments to python.exe (it was missing in my registry for some reason).

My setting was under yet another registry key, HKEY_CLASSES_ROOT\py_auto_file. The other keys mentioned also existed, but Windows was using this one for some reason.

For Python 3.3 on Windows 7, my setting was under another registry key; the key I changed to make the arguments get passed was

HKEY_USERS\S-1-5-21-3922133726-554333396-2662258059-1000_Classes\py_auto_file\shell\open\command

It was "C:\Python\Python33\python.exe" "%1". I only appended %* to it. The key's value is now "C:\Python\Python33\python.exe" "%1" %*.

I had several (at least five) other keys with the value "C:\Python\Python33\python.exe" "%1", but this is the one I changed that made it work.

To make it working for me, I had to use the registry path:

HKEY_CLASSES_ROOT\py_auto_file\shell\open\command

and added a %*

Here are .reg files to fix for Python 3.6, 2.7 and Anaconda3:

python-3.6.0.reg

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\.py]
@="Python.File"
"Content Type"="text/plain"

[HKEY_CLASSES_ROOT\.pyc]
@="Python.CompiledFile"
"Content Type"="text/plain"

[HKEY_CLASSES_ROOT\.pyw]
@="Python.NoConFile"
"Content Type"="text/plain"


[HKEY_CLASSES_ROOT\py_auto_file]

[HKEY_CLASSES_ROOT\py_auto_file\DefaultIcon]
@="C:\\Python36\\DLLs\\py.ico"

[HKEY_CLASSES_ROOT\py_auto_file\shell\open\command]
@="\"C:\\Python36\\python.exe\" \"%1\" %*"


[HKEY_CLASSES_ROOT\Python.File]
@="Python File"

[HKEY_CLASSES_ROOT\Python.File\DefaultIcon]
@="C:\\Python36\\DLLs\\py.ico"

[HKEY_CLASSES_ROOT\Python.File\shell\open\command]
@="\"C:\\Python36\\python.exe\" \"%1\" %*"


[HKEY_CLASSES_ROOT\Python.CompiledFile]
@="Compiled Python File"

[HKEY_CLASSES_ROOT\Python.CompiledFile\DefaultIcon]
@="C:\\Python36\\DLLs\\pyc.ico"

[HKEY_CLASSES_ROOT\Python.CompiledFile\shell\open\command]
@="\"C:\\Python36\\python.exe\" \"%1\" %*"


[HKEY_CLASSES_ROOT\Python.NoConFile]
@="Python File (no console)"

[HKEY_CLASSES_ROOT\Python.NoConFile\DefaultIcon]
@="C:\\Python36\\DLLs\\py.ico"

[HKEY_CLASSES_ROOT\Python.NoConFile\shell\open\command]
@="\"C:\\Python36\\python.exe\" \"%1\" %*"

python-2.7.0.reg

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\.py]
@="Python.File"
"Content Type"="text/plain"

[HKEY_CLASSES_ROOT\.pyc]
@="Python.CompiledFile"
"Content Type"="text/plain"

[HKEY_CLASSES_ROOT\.pyw]
@="Python.NoConFile"
"Content Type"="text/plain"


[HKEY_CLASSES_ROOT\py_auto_file]

[HKEY_CLASSES_ROOT\py_auto_file\DefaultIcon]
@="C:\\Python27\\DLLs\\py.ico"

[HKEY_CLASSES_ROOT\py_auto_file\shell\open\command]
@="\"C:\\Python27\\python.exe\" \"%1\" %*"


[HKEY_CLASSES_ROOT\Python.File]
@="Python File"

[HKEY_CLASSES_ROOT\Python.File\DefaultIcon]
@="C:\\Python27\\DLLs\\py.ico"

[HKEY_CLASSES_ROOT\Python.File\shell\open\command]
@="\"C:\\Python27\\python.exe\" \"%1\" %*"


[HKEY_CLASSES_ROOT\Python.CompiledFile]
@="Compiled Python File"

[HKEY_CLASSES_ROOT\Python.CompiledFile\DefaultIcon]
@="C:\\Python27\\DLLs\\pyc.ico"

[HKEY_CLASSES_ROOT\Python.CompiledFile\shell\open\command]
@="\"C:\\Python27\\python.exe\" \"%1\" %*"


[HKEY_CLASSES_ROOT\Python.NoConFile]
@="Python File (no console)"

[HKEY_CLASSES_ROOT\Python.NoConFile\DefaultIcon]
@="C:\\Python27\\DLLs\\py.ico"

[HKEY_CLASSES_ROOT\Python.NoConFile\shell\open\command]
@="\"C:\\Python27\\python.exe\" \"%1\" %*"

ananconda3.reg (change username)

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\.py]
@="Python.File"
"Content Type"="text/plain"

[HKEY_CLASSES_ROOT\.pyc]
@="Python.CompiledFile"
"Content Type"="text/plain"

[HKEY_CLASSES_ROOT\.pyw]
@="Python.NoConFile"
"Content Type"="text/plain"


[HKEY_CLASSES_ROOT\py_auto_file]

[HKEY_CLASSES_ROOT\py_auto_file\DefaultIcon]
@="C:\\Users\\username\\Anaconda3\\DLLs\\py.ico"

[HKEY_CLASSES_ROOT\py_auto_file\shell\open\command]
@="\"C:\\Users\\username\\Anaconda3\\python.exe\" \"%1\" %*"


[HKEY_CLASSES_ROOT\Python.File]
@="Python File"

[HKEY_CLASSES_ROOT\Python.File\DefaultIcon]
@="C:\\Users\\username\\Anaconda3\\DLLs\\py.ico"

[HKEY_CLASSES_ROOT\Python.File\shell\open\command]
@="\"C:\\Users\\username\\Anaconda3\\python.exe\" \"%1\" %*"


[HKEY_CLASSES_ROOT\Python.CompiledFile]
@="Compiled Python File"

[HKEY_CLASSES_ROOT\Python.CompiledFile\DefaultIcon]
@="C:\\Users\\username\\Anaconda3\\DLLs\\pyc.ico"

[HKEY_CLASSES_ROOT\Python.CompiledFile\shell\open\command]
@="\"C:\\Users\\username\\Anaconda3\\python.exe\" \"%1\" %*"


[HKEY_CLASSES_ROOT\Python.NoConFile]
@="Python File (no console)"

[HKEY_CLASSES_ROOT\Python.NoConFile\DefaultIcon]
@="C:\\Users\\username\\Anaconda3\\DLLs\\py.ico"

[HKEY_CLASSES_ROOT\Python.NoConFile\shell\open\command]
@="\"C:\\Users\\username\\Anaconda3\\python.exe\" \"%1\" %*"

If fixed this on my Windows 10 system by editing the following registry keys:

Computer\HKEY_CLASSES_ROOT\py_auto_file\shell\open\command
Computer\HKEY_CLASSES_ROOT\Python.File\Shell\Open\Command
Computer\HKEY_CLASSES_ROOT\Applications\python.exe\shell\open\command

to this value:

"C:\Python27\python.exe" "%1" %*

A lot of thanks for the most of other answers for helping me to find the solution!

My case was to open .py-files with py.exe (not python.exe directly), this case it noted in a couple of comments, but I decided to post this as a separate answer to emphasize the difference.

So I have my .py-files associated with C:\Windows\py.exe and in C:\Windows\py.ini config I have a couple of shebang definitions

[commands]
<my_venv_py> = C:\Programs\my_venv_py\Scripts\python.exe
<my_venv_py_w> = C:\Programs\my_venv_py\Scripts\pythonw.exe

to use in my scripts like this #!<MY_VENV_PY>.

And on Microsoft Windows 7 [Version 6.1.7601] my python script did NOT received the args like this

script.py 1 2

but this worked fine

py script.py 1 2

File associations were OK

> assoc .py
.py=Python.File

> ftype | grep Python
File STDIN:
Python.CompiledFile="C:\Windows\py.exe" "%1" %*
Python.File=C:\Windows\py.exe "%L" %*
Python.NoConFile="C:\Windows\pyw.exe" "%1" %*

I've tried much of registry changes, but the last helped was the following change (saved to a .reg-file and run). I've found this registry key searching "%1" string with initial value "C:\Windows\py.exe" "%1" and added %* in the end as other answers note:

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\Applications\py.exe\shell\open\command]
@="\"C:\\Windows\\py.exe\" \"%1\" %*"

For information, before I tried to setup these keys and values and did not helped (at least before the noted above):

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\.py]
@="Python.File"
[HKEY_CURRENT_USER\Software\Classes\.py]
@="Python.File"
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.py]
@="Python.File"
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.py]
@="Python.File"

[HKEY_CLASSES_ROOT\py_auto_file]
@="Python File"
[HKEY_CLASSES_ROOT\py_auto_file\shell\open\command]
@="\"C:\\Windows\\py.exe\" \"%1\" %*"

[HKEY_CLASSES_ROOT\Python.File]
@="Python File"
[HKEY_CLASSES_ROOT\Python.File\Shell\Open\command]
@="\"C:\\Windows\\py.exe\" \"%1\" %*"

Had to modify this in Windows 10 to get it to work (%* at the end)

Computer\HKEY_USERS\S-1-5-21-2364940108-955964078-1358188674-1001\Software\Classes\Applications\py.exe\shell\open\command

Interesting. Works here using python 2.6 and Windows XP (5.1.2600):

C:\Documents and Settings\hbrown>python test.py foo
['test.py', 'foo']

C:\Documents and Settings\hbrown>test.py foo
['C:\\Documents and Settings\\hbrown\\test.py', 'foo']

C:\Documents and Settings\hbrown>test foo
['C:\\Documents and Settings\\hbrown\\test.py', 'foo']

C:\Documents and Settings\hbrown>type test.py
import sys
print sys.argv 

C:\Documents and Settings\hbrown>echo %PATHEXT%
.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.PY 

C:\Documents and Settings\hbrown>assoc .py
.py=Python.File

Your program associations for .py files might be messed up. Just re-associate .py files with your python executable.

Right click a .py file > Open with > Choose default program ... > [find C:\PythonXY\python.exe]

I checked all registry keys with python.exe and py_auto_file and made them point to my current python installation including th %* at the end that passes arguments. They were quite a few:

• HKEY_CLASSES_ROOT\Applications\python.exe\shell\open\command:

  • org: "C:\miniconda3\python.exe" "%1" "%*"
  • changed: "C:\Python35\python.exe" "%1" "%*"

• HKEY_CLASSES_ROOT\py_auto_file\shell\open\command

  • org: "C:\Program Files\Sublime Text 3\sublime_text.exe" "%1"
  • changed: "C:\Python35\python.exe" "%1" "%*"

• HKEY_CURRENT_USER\Software\Classes\py_auto_file\shell\open\command

  • org: "C:\Python35\python.exe" "%1" "%*"

• HKEY_USERS\S-1-5-21-2621213409-1291422344-4183577876-2165\Software\Classes\py_auto_file\shell\open\command

  • org: "C:\Python35\python.exe" "%1" "%*"

• HKEY_USERS\S-1-5-21-2621213409-1291422344-4183577876-2165_Classes\py_auto_file\shell\open\command

  • org: "C:\Python35\python.exe" "%1" "%*"

• HKEY_CLASSES_ROOT\Applications\pythonw.exe\shell\open\command

  • org: "C:\Python34\pythonw.exe" "%1"
  • changed: "C:\Python35\pythonw.exe" "%1" "%*"

• HKEY_CURRENT_USER\Software\Classes\Applications\python.exe\shell\open\command

  • org: "C:\Python35\python.exe" "%1" "%*"

But that didn't do the job for me. I had to change my default python application as well.

As one can see I have 3 Python versions installed. It is impossible to see which is which here so I tried all three of them as my default python application. Eventually I was able to get my script arguments with one of these three.

By looking through the Windows registry, I found all the places where anything like Python36\pythonw.exe "%1" %* appears.

When I type python app.py args at the command prompt, everything works properly.

When I use just the app name (app.py args) Windows opens app.py in Python, but the app fails when it tries to access argv[1], because len(argv) is 1.

Apparently Windows knows enough to pass a py file to Python, but I can't figure out from looking at registry entries how it constructs the command. It appears to be using "%1" rather than "%1" %*.