[Python](EN) Get environment variable

Post about get environment variable

Environment and Prerequisite

• Python 3.X or higher

Get Environment Variable

Use os Module

Basic Form

• Returns the environment variable key if it exists.
• If key does not exists, then return default value.
• If default is not set and environment variable of key does not exists, then return None.
• Return type of environment variable is str.

os.getenv(key, default=None)

Example

• Set environment variable

export TEST="TEST env value"
export NUM=123

• Get environment variable

>>> import os
>>> os.getenv("TEST", "TEST env default value")
'TEST env value'

• Check return type

>>> import os
>>> type(os.getenv("NUM", "NUM env default value"))
<class 'str'>

• Get default if key does not exists

>>> import os
>>> os.getenv("default", "TEST env default value")
'TEST env default value'
>>> type(os.getenv("default", "TEST env default value"))
<class 'str'>

>>> import os
>>> os.getenv("default", 12345)
12345
>>> type(os.getenv("default", 12345))
<class 'int'>

• Return None if both key and default does not exists

>>> import os
>>> type(os.getenv("NONE TEST"))
<class 'NoneType'>

Reference

• https://docs.python.org/ko/3.5/library/os.html#os.getenv