Accessing Environment Variables in Python

To access environment variables in Python, utilize the os.environ object, which represents a mapping of environment variable names to their values. By default, accessing the variable within the mapping prompts the interpreter to search the Python dictionary for its value.

Retrieving a Single Variable

To retrieve the value of a specific environment variable, use the following syntax:

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

Replace 'HOME' with the name of the variable you want to access.

Displaying All Variables

To list all the environment variables, print the os.environ object as a dictionary:

print(os.environ)

Handling Missing Variables

Attempting to access a non-existent environment variable will trigger a KeyError. To avoid this:

os.environ.get()

Returns 'None' if the variable doesn't exist:

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

with Default Value

Returns 'default_value' if the variable doesn't exist:

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

os.getenv()

Similar to os.environ.get(), but with the option to supply a default value:

print(os.getenv('KEY_THAT_MIGHT_EXIST', default_value))