Python | os.getenv() method

OS module in Python provides functions for interacting with the operating system. OS comes under Python’s standard utility modules. This module provides a portable way of using operating system dependent functionality.

os.getenv() method in Python returns the value of the environment variable key if it exists otherwise returns the default value.

Syntax: os.getenv(key, default = None)

Parameters:
key: string denoting the name of environment variable
default (optional) : string denoting the default value in case key does not exists. If omitted default is set to ‘None’.

Return Type: This method returns a string that denotes the value of the environment variable key. In case key does not exists it returns the value of default parameter.

Code #1: use of os.getenv() method

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# Python program to explain os.getenv() method 
    
# importing os module 
import os
  
# Get the value of 'HOME'
# environment variable
key = 'HOME'
value = os.getenv(key)
  
# Print the value of 'HOME'
# environment variable
print("Value of 'HOME' environment variable :", value) 
  
# Get the value of 'JAVA_HOME'
# environment variable
key = 'JAVA_HOME'
value = os.getenv(key)
  
# Print the value of 'JAVA_HOME'
# environment variable
print("Value of 'JAVA_HOME' environment variable :", value) 

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Output:

Value of 'HOME' environment variable : /home/ihritik
Value of 'JAVA_HOME' environment variable : /opt/jdk-10.0.1

 

Code #2: if key does not exist

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# Python program to explain os.getenv() method 
    
# importing os module 
import os
  
# Get the value of 'home'
# environment variable
key = 'home'
value = os.getenv(key)
  
# Print the value of 'home'
# environment variable
print("Value of 'home' environment variable :", value)

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Output:

Value of 'home' environment variable : None

 

Code #3: Explicitly specifying default parameter

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# Python program to explain os.getenv() method 
    
# importing os module 
import os
  
# Get the value of 'home'
# environment variable
key = 'home'
value = os.getenv(key, "value does not exist")
  
# Print the value of 'home'
# environment variable
print("Value of 'home' environment variable :", value) 

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Output:

Value of 'home' environment variable : value does not exist


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