How to set environment variables in Python?

Use os.environ method to manage variables

Setting environment variables

Add or change environment variables with a simple Python assignment:

# My first environment variable! Mom will be so proud!
os.environ['MY_VAR'] = 'Hello, World!' 
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Checking existence of a variable

Ensure an environment variable exists before using it. Your script will thank you.

if 'MY_VAR' in os.environ:
    print("Mom's watching!") 
else:
    print("You're forgotten, mate!")
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Wrestling with non-string variables

Dealing with non-strings? Python's got your back. Just convert them:

os.environ['LUCKY_NUMBER'] = str(7)  # Saving your lucky number as an environment variable (just don't tell anyone!)
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Scope and persistence of environment variables

Temporary vs. Permanent settings

Variables set with os.environ impact the current process and child processes. Use wisely - they're not here for a long time, just a good time.

Making permanent system variables in Windows

For a deeper impact on the system, Windows users, use SETX:

os.system('SETX SOUP_RECIPE "Delicious" /M')  # '/M' is like chanting a permanent spell, but less magical and more annoying
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Advanced tips and tricks with environment variables

Using .env files for storing variables

Friends don't let friends hard-code environment variables. Use a .env file:

from dotenv import load_dotenv

load_dotenv('/path/to/.env')  # Embrace the power of .env files!
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Controlling environment for subprocesses

While creating subprocesses, command the environment like a boss:

import subprocess

my_env = os.environ.copy()
my_env["SECRET_KEY"] = "abc123"

# Spawning a subprocess with your secret key. Let the chaos reign!
subprocess.run(["some_command"], env=my_env) 
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