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

Question

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 configuration has:

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

>assoc .py
.py=Python.File

>ftype | grep Python
Python.CompiledFile="C:Python25python.exe" "%1" %*
Python.File="C:Python25python.exe" "%1" %*
Python.NoConFile="C:Python25pythonw.exe" "%1" %*

Asked By: mckoss

||

Source

Answer 1

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

C:Documents and Settingshbrown>python test.py foo
['test.py', 'foo']

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

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

C:Documents and Settingshbrown>type test.py
import sys
print sys.argv 

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

C:Documents and Settingshbrown>assoc .py
.py=Python.File

Answered By: hughdbrown

Answer 2

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_ROOTPython.Fileshellopencommand):

[HKEY_CLASSES_ROOTApplicationspython.exeshellopencommand]
@=""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).

Answered By: mckoss

Answer 3

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

Answered By: bainorama

Answer 4

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_USERSS-1-5-21-3922133726-554333396-2662258059-1000_Classespy_auto_fileshellopencommand

It was "C:PythonPython33python.exe" "%1". I only appended %* to it. The key’s value is now "C:PythonPython33python.exe" "%1" %*.

I had several (at least five) other keys with the value "C:PythonPython33python.exe" "%1", but this is the one I changed that made it work.

Answered By: Cody Piersall

Answer 5

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

HKEY_CLASSES_ROOTpy_auto_fileshellopencommand

and added a %*

Answered By: rundekugel

Answer 6

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:PythonXYpython.exe]

Answered By: congusbongus

Answer 7

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_ROOTApplicationspython.exeshellopencommand:

org: “C:miniconda3python.exe” “%1” “%*”

changed: “C:Python35python.exe” “%1” “%*”

HKEY_CLASSES_ROOTpy_auto_fileshellopencommand

org: “C:Program FilesSublime Text 3sublime_text.exe” “%1”

changed: “C:Python35python.exe” “%1” “%*”

HKEY_CURRENT_USERSoftwareClassespy_auto_fileshellopencommand

org: “C:Python35python.exe” “%1” “%*”

HKEY_USERSS-1-5-21-2621213409-1291422344-4183577876-2165SoftwareClassespy_auto_fileshellopencommand

org: “C:Python35python.exe” “%1” “%*”

HKEY_USERSS-1-5-21-2621213409-1291422344-4183577876-2165_Classespy_auto_fileshellopencommand

org: “C:Python35python.exe” “%1” “%*”

HKEY_CLASSES_ROOTApplicationspythonw.exeshellopencommand

org: “C:Python34pythonw.exe” “%1”

changed: “C:Python35pythonw.exe” “%1” “%*”

HKEY_CURRENT_USERSoftwareClassesApplicationspython.exeshellopencommand

org: “C:Python35python.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.

Answered By: MrLeeh

Answer 8

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_ROOTpy_auto_file]

[HKEY_CLASSES_ROOTpy_auto_fileDefaultIcon]
@="C:\Python36\DLLs\py.ico"

[HKEY_CLASSES_ROOTpy_auto_fileshellopencommand]
@=""C:\Python36\python.exe" "%1" %*"


[HKEY_CLASSES_ROOTPython.File]
@="Python File"

[HKEY_CLASSES_ROOTPython.FileDefaultIcon]
@="C:\Python36\DLLs\py.ico"

[HKEY_CLASSES_ROOTPython.Fileshellopencommand]
@=""C:\Python36\python.exe" "%1" %*"


[HKEY_CLASSES_ROOTPython.CompiledFile]
@="Compiled Python File"

[HKEY_CLASSES_ROOTPython.CompiledFileDefaultIcon]
@="C:\Python36\DLLs\pyc.ico"

[HKEY_CLASSES_ROOTPython.CompiledFileshellopencommand]
@=""C:\Python36\python.exe" "%1" %*"


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

[HKEY_CLASSES_ROOTPython.NoConFileDefaultIcon]
@="C:\Python36\DLLs\py.ico"

[HKEY_CLASSES_ROOTPython.NoConFileshellopencommand]
@=""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_ROOTpy_auto_file]

[HKEY_CLASSES_ROOTpy_auto_fileDefaultIcon]
@="C:\Python27\DLLs\py.ico"

[HKEY_CLASSES_ROOTpy_auto_fileshellopencommand]
@=""C:\Python27\python.exe" "%1" %*"


[HKEY_CLASSES_ROOTPython.File]
@="Python File"

[HKEY_CLASSES_ROOTPython.FileDefaultIcon]
@="C:\Python27\DLLs\py.ico"

[HKEY_CLASSES_ROOTPython.Fileshellopencommand]
@=""C:\Python27\python.exe" "%1" %*"


[HKEY_CLASSES_ROOTPython.CompiledFile]
@="Compiled Python File"

[HKEY_CLASSES_ROOTPython.CompiledFileDefaultIcon]
@="C:\Python27\DLLs\pyc.ico"

[HKEY_CLASSES_ROOTPython.CompiledFileshellopencommand]
@=""C:\Python27\python.exe" "%1" %*"


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

[HKEY_CLASSES_ROOTPython.NoConFileDefaultIcon]
@="C:\Python27\DLLs\py.ico"

[HKEY_CLASSES_ROOTPython.NoConFileshellopencommand]
@=""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_ROOTpy_auto_file]

[HKEY_CLASSES_ROOTpy_auto_fileDefaultIcon]
@="C:\Users\username\Anaconda3\DLLs\py.ico"

[HKEY_CLASSES_ROOTpy_auto_fileshellopencommand]
@=""C:\Users\username\Anaconda3\python.exe" "%1" %*"


[HKEY_CLASSES_ROOTPython.File]
@="Python File"

[HKEY_CLASSES_ROOTPython.FileDefaultIcon]
@="C:\Users\username\Anaconda3\DLLs\py.ico"

[HKEY_CLASSES_ROOTPython.Fileshellopencommand]
@=""C:\Users\username\Anaconda3\python.exe" "%1" %*"


[HKEY_CLASSES_ROOTPython.CompiledFile]
@="Compiled Python File"

[HKEY_CLASSES_ROOTPython.CompiledFileDefaultIcon]
@="C:\Users\username\Anaconda3\DLLs\pyc.ico"

[HKEY_CLASSES_ROOTPython.CompiledFileshellopencommand]
@=""C:\Users\username\Anaconda3\python.exe" "%1" %*"


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

[HKEY_CLASSES_ROOTPython.NoConFileDefaultIcon]
@="C:\Users\username\Anaconda3\DLLs\py.ico"

[HKEY_CLASSES_ROOTPython.NoConFileshellopencommand]
@=""C:\Users\username\Anaconda3\python.exe" "%1" %*"

Answered By: iki

Answer 9

By looking through the Windows registry, I found all the places where anything like
Python36pythonw.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" %*.

Answered By: Richard Mateosian

Answer 10

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

ComputerHKEY_CLASSES_ROOTpy_auto_fileshellopencommand
ComputerHKEY_CLASSES_ROOTPython.FileShellOpenCommand
ComputerHKEY_CLASSES_ROOTApplicationspython.exeshellopencommand

to this value:

"C:Python27python.exe" "%1" %*

Answered By: stuw

Answer 11

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:Windowspy.exe and in C:Windowspy.ini config I have a couple of shebang definitions

[commands]
<my_venv_py> = C:Programsmy_venv_pyScriptspython.exe
<my_venv_py_w> = C:Programsmy_venv_pyScriptspythonw.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:Windowspy.exe" "%1" %*
Python.File=C:Windowspy.exe "%L" %*
Python.NoConFile="C:Windowspyw.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:Windowspy.exe" "%1" and added %* in the end as other answers note:

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOTApplicationspy.exeshellopencommand]
@=""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_USERSoftwareClasses.py]
@="Python.File"
[HKEY_LOCAL_MACHINESOFTWAREClasses.py]
@="Python.File"
[HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionExplorerFileExts.py]
@="Python.File"

[HKEY_CLASSES_ROOTpy_auto_file]
@="Python File"
[HKEY_CLASSES_ROOTpy_auto_fileshellopencommand]
@=""C:\Windows\py.exe" "%1" %*"

[HKEY_CLASSES_ROOTPython.File]
@="Python File"
[HKEY_CLASSES_ROOTPython.FileShellOpencommand]
@=""C:\Windows\py.exe" "%1" %*"

Answered By: and1er

Answer 12

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

ComputerHKEY_USERSS-1-5-21-2364940108-955964078-1358188674-1001SoftwareClassesApplicationspy.exeshellopencommand

Answered By: Arunex

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

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