python - How to access environment variable values?

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

Answer

Environment variables are accessed through
rel="noreferrer">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))

href="https://docs.python.org/install/index.html#how-installation-works"
rel="noreferrer">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)