apt-get install python
python -V

apt-get install python3.6
python3 -V
python3.6 -V

apt install python-pip
pip -V

apt install python3-pip
pip3 -V

pip freeze
pip freeze > requirements.txt
pip install -r requirements.txt

pip install virtualenv
pip3 install virtualenv

virtualenv[virtual_name]
source [virtual_name]/bin/activate
deactivate