Python 3 comes bundled with the venv module to create virtual environments
Create a project folder and a venv folder within:
mkdir myproject
cd myproject
python3 -m venv venv
Before you work on your project, activate the corresponding environment:
. venv/bin/activate
Your shell prompt will change to show the name of the activated environment
Within the activated environment, use the following command to install Flask:
pip install Flask
原文：https://www.cnblogs.com/zxpo/p/9650891.html