How Can I Access and Manage Environment Variables in Python?

Accessing Environment Variables in Python

Accessing environment variables in Python is a crucial task for interacting with the system's configuration and user-defined settings. In this article, we'll explore how to retrieve the value of an environment variable and list all available variables using Python's built-in capabilities.

Retrieving Environment Variable Value

To access the value of an environment variable, use the os.environ dictionary-like object:

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

This prints the value of the HOME environment variable, which typically points to the user's home directory.

Getting All Environment Variables

To see a comprehensive list of all environment variables accessible to your Python program:

print(os.environ)

This will output a comprehensive dictionary of all available environment variables and their values.

Handling Missing or Null Values

By default, attempting to access a non-existent environment variable will raise a KeyError. To prevent this:

• Use os.environ.get(): Returns None if the key doesn't exist.

print(os.environ.get('KEY_THAT_MIGHT_EXIST'))

• Use os.environ.get(key, default_value): Returns default_value if the key doesn't exist.

print(os.environ.get('KEY_THAT_MIGHT_EXIST', 'Default Value'))

• Use os.getenv(): Also returns default_value if the key doesn't exist.

print(os.getenv('KEY_THAT_MIGHT_EXIST', 'Default Value'))

The above is the detailed content of How Can I Access and Manage Environment Variables in Python?. For more information, please follow other related articles on the PHP Chinese website!