Python | os.getenvb() 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.getenvb() method in Python is bytes version of os.getenv() method. This method also returns the value of the environment variable associated with specified key. But unlike os.getenv() method, it accepts a bytes object as the key and returns a bytes object as the value of the environment variable associated with specified key.

The functionality of os.getenvb() method is available only if the native OS type of the environment is bytes. For example, Windows do not have bytes as the native OS type of the environment so the functionality of os.getenvb() method is not available on Windows.

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

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

Return Type: This method returns a bytes object which denotes the value of the environment variable associated with specified key. In case key does not exists it returns the value of default parameter.

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

# Python program to explain os.getenvb() method

# importing os module
import os

# Get the value of 'HOME'
# environment variable
key = b'HOME'
value = os.getenvb(key)

# Print the value of 'HOME'
# environment variable
print("Value of 'HOME' environment variable :", value)

# Get the value of 'JAVA_HOME'
# environment variable
key = b'JAVA_HOME'
value = os.getenvb(key)

# Print the value of 'JAVA_HOME'
# environment variable
print("Value of 'JAVA_HOME' environment variable :", value)

Output:

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

Code #2: If key does not exist

# Python program to explain os.getenvb() method

# importing os module
import os

# Get the value of 'home'
# environment variable
key = b'home'
value = os.getenvb(key)

# Print the value of 'home'
# environment variable
print("Value of 'home' environment variable :", value)

Output:

Value of 'home' environment variable : None

Code #3: Explicitly specifying default parameter

# Python program to explain os.getenvb() method

# importing os module
import os

# Get the value of 'home'
# environment variable
key = b'home'
value = os.getenvb(key, default = "value does not exist")

# Print the value of 'home'
# environment variable
print("Value of 'home' environment variable :", value)

Output:

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

Reference: https://docs.python.org/3/library/os.html#os.getenvb()