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I have strange problem:

When I execute this: 

print(os.environ)

in python.exe, I see one thing and in IDLE (pythonw.exe) another, why?

May be this is some kind of cache or what?

PS my system: Windows 7 x64 and Python 3.5.1 x32

Why you mark it duplicate, I didnt found answer for this type of issue. I read about difference of python.exe and pythonw.exe, but I don't understand why PATH variable is differents.

Here is defference:

python.exe:

C:\ProgramData\Oracle\Java\javapath;C:\Program Files (x86)\Intel\iCLS Client\;C:\Program Files\Intel\iCLS Client\;C:\Program Files\Broadcom\Broadcom 802.11 Network Adapter\Driver;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files\Lenovo\Bluetooth Software\;C:\Program Files\Lenovo\Bluetooth Software\syswow64;C:\Program Files (x86)\Intel\OpenCL SDK\2.0\bin\x86;C:\Program Files (x86)\Intel\OpenCL SDK\2.0\bin\x64;C:\Program Files\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files (x86)\Skype\Phone\;C:\Program Files\Git\cmd;C:\Program Files (x86)\nodejs\;C:\Users\someusername\AppData\Local\Programs\ Python\Python35-32\Scripts\;C:\Users\someusername\AppData\Local\Programs\Python\Python35-32\;C:\Program Files (x86)\nodejs\;C:\Users\someusername\AppData\Roaming\npm

pythonw.exe:

C:\ProgramData\Oracle\Java\javapath;C:\Program Files (x86)\Intel\iCLS Client\;C:\Program Files\Intel\iCLS Client\;C:\Program Files\Broadcom\Broadcom 802.11 Network Adapter\Driver;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files\Lenovo\Bluetooth Software\;C:\Program Files\Lenovo\Bluetooth Software\syswow64;C:\Program Files (x86)\Intel\OpenCL SDK\2.0\bin\x86;C:\Program Files (x86)\Intel\OpenCL SDK\2.0\bin\x64;C:\Program Files\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files (x86)\Skype\Phone\;C:\Program Files\Git\cmd;C:\Users\someusername\AppData\Local\Programs\Python\Python35-32\Scripts\;C:\Users\someusername\AppData\Local\Programs\Python\Python35-32\

Do you see nodejs path in python.exe result, and not of it in pythonw.exe? I deleted all pyc file but that not helps

Xion
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  • “I see one thing […] and another” What things? There are many different environment variables, you have to be more specific than that. – poke Feb 08 '16 at 20:24
  • @jonrsharpe While that other question covers the `python` vs `pythonw` part of the question, the used executable has very little to do with the environment variables that OP is talking about. Also their use of `pythonw` is only through IDLE, which does behave similarly enough to just `python` to make this question really not about `python` vs `pythonw`. – poke Feb 08 '16 at 20:29
  • @Xion Please actually tell us what differences you see, otherwise we won’t be able to explain why you are seeing them. – poke Feb 08 '16 at 20:40
  • Please change the title of the question, since it does not describe what you ask. You environment listing should show just the difference. The common items are irrelevant. You should also say how you started python.exe versus how you started pythonw.exe (via IDLE). Either can be started in various ways. – Terry Jan Reedy Feb 08 '16 at 21:15

1 Answers1

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The value of the PATH environment variable has very little to do with the difference between python.exe and pythonw.exe. What you need to know about PATH, or environment variables in general, is that they are usually inherited from the calling process.

So when you call python.exe from the command line, then that process will inherit the value of PATH that the command line had. If you open IDLE using some shortcut, then it will inherit the value from Windows.

Every process can mess with the environment variables as much as they like; and as such affect processes they start. For example:

C:\>set FOO=Hello world
C:\>py -3
Python 3.5.0 (v3.5.0:374f501f4567, Sep 13 2015, 02:27:37) [MSC v.1900 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> os.environ['FOO']
'Hello world'
>>> ^Z

C:\>set FOO=Hello world foo bar baz
C:\>py -3
Python 3.5.0 (v3.5.0:374f501f4567, Sep 13 2015, 02:27:37) [MSC v.1900 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> os.environ['FOO']
'Hello world foo bar baz'

And just like that I created a new environment variable FOO which was passed automatically to the process I was starting (Python 3), which could access it there.

The same really applies to the PATH environment variable. If you are seeing differences there, it’s likely not because your executable is different, but more because the calling process may have affected it in a different way.

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poke
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  • I understand PATH usage, but what about pythonw.exe? where it can get its own PATH var? I need pythonw.exe to get valid PATH var with nodejs path – Xion Feb 08 '16 at 21:13
  • In doubt, it gets it from Windows’ environment settings. But note that your “pythonw.exe” example is actually a subset of the other one. The Nodejs related directories are the only ones that are left out. So it’s likely that the other case—the “python.exe” one—is actually augmented by those paths. But again: This has nothing to do with `pythonw.exe`. – poke Feb 08 '16 at 21:16