test.py

  cargo git:(master) echo $NAME 

➜  cargo git:(master) export NAME='Srinivas'
➜  cargo git:(master) echo $NAME            
Srinivas
➜  cargo git:(master) python
Python 2.7.12 (default, Nov 20 2017, 18:23:56) 
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import o
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named o
>>> import os
>>> print os.environ.get('NAME')
Srinivas
>>> print os.environ.get('LAST_NAME')
None
>>> print os.environ.get('LAST_NAME', 'Reddy')
Reddy
>>>