env-variable part 1

env_vars.py

import os

# first way
os.environ['TERM_PROGRAM']
# => 'Apple_Terminal'
# a non-existing variable will lead to error
os.environ["THIS_VARIABLE_DOESNT_EXIST"]
# => KeyError: 'THIS_VARIABLE_DOESNT_EXIST'

# second way
print(os.getenv("TERM_PROGRAM"))
# => 'Apple_Terminal'
# a non-existing variable will lead to None
print(os.getenv("THIS_VARIABLE_DOESNT_EXIST"))
# => None
# but you could also specify if you want it to return
# something else if the key does not exist
print(os.getenv("THIS_VARIABLE_DOESNT_EXIST", "Return this if it does not exist..."))
# => "Return this if it does not exist..."