python virtualenv

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

source env/bin/activate

#all this is on same directory

### VIRTUAL ENVIRONMENT 

pip install virtualenv

virtualenv pas # write the folder name 

.\foldername\Scripts\activate # to activate the virtual environment 

pip freeze # to get all the modules in the base interpretor / virtual env

pip freeze > requirements.txt # to set the modules and their versions in the requirement file 

pip install -r requirements.txt # to install all the modules with their respected versions in the virtual env

virtualenv --system-site-packages-foldername # this creates virtual env with all the modules and versions that are preinstalled on base python interpretor 

deactivate # to come out of the virtual env

$ pip install virtualenv

python -m venv my_env

python3 -m venv tutorial-env

$ cd project_folder
$ virtualenv venv

source env/bin/activate

python3 -m pip install --user virtualenv

$ virtualenv --version

$ export VIRTUALENVWRAPPER_PYTHON=/usr/bin/python2.7