How to access environment variable values?

python environment-variables
Amit Yadav picture Amit Yadav · Feb 5, 2011 · Viewed 2M times · Source

I set an environment variable that I want to access in my Python application. How do I get its value?

Answer

Rod picture Rod · Feb 5, 2011

Environment variables are accessed through os.environ

import os
print(os.environ['HOME'])

Or you can see a list of all the environment variables using:

os.environ

As sometimes you might need to see a complete list!

# using get will return `None` if a key is not present rather than raise a `KeyError`
print(os.environ.get('KEY_THAT_MIGHT_EXIST'))

# os.getenv is equivalent, and can also give a default value instead of `None`
print(os.getenv('KEY_THAT_MIGHT_EXIST', default_value))

Python default installation on Windows is C:\Python. If you want to find out while running python you can do:

import sys
print(sys.prefix)

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