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 is_windows():
  ...

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 is_windows. 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 495 · Accepted Answer · edited Feb 19 '19 at 14:08

495

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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82

'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
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"... `'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
1

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

51

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

42

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

19

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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