Environment
Window:
python3 -m venv env
cd env
.\Scripts\activate.bat
cd ..
c:\Users\StanleyChan\AppData\Local\Programs\Python\Python38\python.exe -m venv env
Ubuntu
python3 -m venv env
source env\Scripts\activate
Package
Output installed packages in requirements format.
python -m pip freeze
To install packages in requirements format
py -m pip install -r requirements.txt
Generate a requirements file and then install from it in another environment.
env1\\bin\\python -m pip freeze > requirements.txt
env2\\bin\\python -m pip install -r requirements.txt
Rereference: https://pip.pypa.io/en/stable/cli/pip_freeze/