Environment

How to get and set environment variables in Python?

import os

# get HOME directory

os.environ.get('HOME') # returns None if variable does not exist

'/home/myusername'

os.getenv('TOOLS', os.getcwd() ) # returns second alternative value (working directory), if variable 'TOOLS' does not exist

'/my/current/working/directory'

# set HOME directory

os.environ['HOME']='/home/user/my/new/home/directory/'

# add new directory to system PATH

newpath='/home/username/tools'

# append to PATH

os.environ['PATH'] += os.pathsep + newpath

# or, set new path in beginning of PATH

os.environ['PATH'] = newpath + os.pathsep + os.environ['PATH']

# or, using: os.pathsep.join( [list, of, multiple, paths] )

os.environ['PATH'] = os.pathsep.join( [ newpath, os.environ['PATH'] ] )

# check: print PATH environment variable

print(os.environ['PATH'])