Python: What OS am I running on?

Question

What do I need to look at to see whether I\'m on Windows or Unix, etc?

Answer 1

Short Story

Use platform.system(). It returns Windows, Linux or Darwin (for OSX).

Long Story

There are 3 ways to get OS in Python, each with its own pro and cons:

Method 1

>>> import sys
>>> sys.platform
'win32'  # could be 'linux', 'linux2, 'darwin', 'freebsd8' etc

How this works (source): Internally it calls OS APIs to get name of the OS as defined by OS. See here for various OS-specific values.

Pro: No magic, low level.

Con: OS version dependent, so best not to use directly.

Method 2

>>> import os
>>> os.name
'nt'  # for Linux and Mac it prints 'posix'

How this works (source): Internally it checks if python has OS-specific modules called posix or nt.

Pro: Simple to check if posix OS

Con: no differentiation between Linux or OSX.

Method 3

>>> import platform
>>> platform.system()
'Windows' # for Linux it prints 'Linux', Mac it prints `'Darwin'

How this works (source): Internally it will eventually call internal OS APIs, get OS version-specific name like 'win32' or 'win16' or 'linux1' and then normalize to more generic names like 'Windows' or 'Linux' or 'Darwin' by applying several heuristics.

Pro: Best portable way for Windows, OSX and Linux.

Con: Python folks must keep normalization heuristic up to date.

Summary

• If you want to check if OS is Windows or Linux or OSX then the most reliable way is platform.system().
• If you want to make OS-specific calls but via built-in Python modules posix or nt then use os.name.
• If you want to get raw OS name as supplied by OS itself then use sys.platform.