How do I check if I'm running on Windows in Python?

Question

I found the platform module but it says it returns 'Windows' and it's returning 'Microsoft' on my machine. I notice in another thread here on stackoverflow it returns 'Vista' sometimes.

So, the question is, how do implemement?

if isWindows():
  ...

In a forward compatible way? If I have to check for things like 'Vista' then it will break when the next version of windows comes out.

Note: The answers claiming this is a duplicate question do not actually answer the question isWindows. They answer the question "what platform". Since many flavors of windows exist none of them comprehensively describe how to get an answer of isWindows.

Similar to http://stackoverflow.com/questions/196930/how-to-check-if-os-is-vista-in-python — monkut, Aug 25 '09 at 01:27
"There should be one-- and preferably only one --obvious way to do it." Alas, python gives us at least three ways.. — John Fouhy, Aug 25 '09 at 01:35
Nit: [According to PEP8](https://www.python.org/dev/peps/pep-0008/#function-and-variable-names) you should prefer using the name `is_windows` over `isWindows`. — phoenix, Jan 13 '19 at 12:56

score 445 · Accepted Answer · edited Feb 19 '19 at 14:08

445

Python os module

Specifically for Python 3.6/3.7:

os.name: The name of the operating system dependent module imported. The following names have currently been registered: 'posix', 'nt', 'java'.

In your case, you want to check for 'nt' as os.name output:

import os

if os.name == 'nt':
     ...

There is also a note on os.name:

See also sys.platform has a finer granularity. os.uname() gives system-dependent version information.

The platform module provides detailed checks for the system’s identity.

edited Feb 19 '19 at 14:08

Joel

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answered Aug 25 '09 at 01:17

Martin Beckett

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'nt' is the value for windows – shuckc Feb 26 '14 at 15:12
2

What does linux normally return? posix? – Andi Jay Apr 18 '14 at 17:41
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@AndiJay - yes, but should be easy enough to test! – Martin Beckett Apr 18 '14 at 17:42
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@MartinBeckett - Not necessarily. You may not have a machine running Linux available. – ArtOfWarfare Jan 05 '15 at 18:49
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@ArtOfWarfare you don't need a machine ;) https://onlinegdb.com/HyhJEzdX4 ( Well maybe in 2015 ) – jay Jan 25 '19 at 04:44
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It turns out that `os.name` is actually not a good way. You want to use `platform.system()` instead. Here's the detailed answer: https://stackoverflow.com/a/58071295/207661 – Shital Shah Sep 23 '19 at 23:38
1

"... `'posix'`, `'nt'`, `'java'`" Of course, Windows can run java, so this quote in your answer shows that testing for `'nt'` is a bad way to test whether you're running on Windows. – Arthur Tacca Sep 02 '20 at 11:22
What is the `'java'` OS ? Linux and Windows make sense but Java isn't an OS, is it ? – Haltarys Feb 10 '21 at 21:25
`system.uname()`, not `os.uname()` :) – Piotr Wasilewicz Jun 18 '21 at 16:28

Mark Rushakoff · Answer 2 · 2009-08-25T01:31:57.277

Are you using platform.system?

 system()
        Returns the system/OS name, e.g. 'Linux', 'Windows' or 'Java'.

        An empty string is returned if the value cannot be determined.

If that isn't working, maybe try platform.win32_ver and if it doesn't raise an exception, you're on Windows; but I don't know if that's forward compatible to 64-bit, since it has 32 in the name.

win32_ver(release='', version='', csd='', ptype='')
        Get additional version information from the Windows Registry
        and return a tuple (version,csd,ptype) referring to version
        number, CSD level and OS type (multi/single
        processor).

But os.name is probably the way to go, as others have mentioned.

For what it's worth, here's a few of the ways they check for Windows in platform.py:

if sys.platform == 'win32':
#---------
if os.environ.get('OS','') == 'Windows_NT':
#---------
try: import win32api
#---------
# Emulation using _winreg (added in Python 2.0) and
# sys.getwindowsversion() (added in Python 2.3)
import _winreg
GetVersionEx = sys.getwindowsversion
#----------
def system():

    """ Returns the system/OS name, e.g. 'Linux', 'Windows' or 'Java'.    
        An empty string is returned if the value cannot be determined.   
    """
    return uname()[0]

On a 64 bit machine, with Windows 7 (64 bit OS) this is the output: Python 3.1.1 (r311:74483, Aug 17 2009, 16:45:59) [MSC v.1500 64 bit (AMD64)] on win32 >>> print(sys.platform) win32 >>> platform.win32_ver() ('post2008Server', '6.1.7100', '', 'Multiprocessor Free') Note that the build explicitly calls it win32. — Francesco, Aug 25 '09 at 21:17
Oops, I thought the output would have been formatted better. hope you can read it anyway. — Francesco, Aug 25 '09 at 21:18

Eevee · Answer 3 · 2013-08-23T18:31:47.563

49

You should be able to rely on os.name.

import os
if os.name == 'nt':
    # ...

edit: Now I'd say the clearest way to do this is via the platform module, as per the other answer.

edited Aug 23 '13 at 18:31

answered Aug 25 '09 at 01:18

Eevee

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score 37 · Answer 4 · edited Nov 19 '15 at 13:39

37

in sys too:

import sys
# its win32, maybe there is win64 too?
is_windows = sys.platform.startswith('win')

edited Nov 19 '15 at 13:39

user2683246

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answered Aug 25 '09 at 01:21

Jochen Ritzel

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I'm on 64 bit Windows and this gives me 'win32' :) – Hut8 Feb 09 '16 at 20:57
@Hut8 I just noticed the same thing. – voices May 24 '18 at 23:41
I'm kind of certain it usually returns 'win32' regardless; at least I've only seen checks for that in code I read. – Sep 08 '18 at 23:21

user2683246 · Answer 5 · 2014-04-03T06:48:01.923

15

import platform
is_windows = any(platform.win32_ver())

or

import sys
is_windows = hasattr(sys, 'getwindowsversion')

edited Apr 03 '14 at 06:48

answered Apr 02 '14 at 18:33

user2683246

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How do I check if I'm running on Windows in Python?

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