how to activate python virtual environment in linux code example

Example 1: python virtual environment

python3 -m venv env
python -m virtualenv env #py2

source env/bin/activate

#all this is on same directory

Example 2: start virtual environment python linux

source env/bin/activate

Example 3: activate venv linux

env/bin/activate

Example 4: activate venv in python

(tutorial-env) $ python -m pip install requests==2.6.0
Collecting requests==2.6.0
  Using cached requests-2.6.0-py2.py3-none-any.whl
Installing collected packages: requests
Successfully installed requests-2.6.0