$ python --version
$ pyenv versions
  3.8.2
* 3.9.6 (set by /home/kumamoto/.pyenv/version)
$ pyenv install 3.9.6
$ pyenv global 3.9.6
$ python --version
Python 3.9.6

[kumamoto poet-practice]$ poetry init

This command will guide you through creating your pyproject.toml config.

Package name [poet-practice]:  
Version [0.1.0]:  
Description []:  
Author [kumamoto <hoge@example.com>, n to skip]:  
License []:  MIT
Compatible Python versions [^3.8]:  ^3.9       

Would you like to define your main dependencies interactively? (yes/no) [yes] no
Would you like to define your development dependencies interactively? (yes/no) [yes] no
Generated file

[tool.poetry]
name = "poet-practice"
version = "0.1.0"
description = ""
authors = ["kumamoto <onioni9999nagare@gmail.com>"]
license = "MIT"

[tool.poetry.dependencies]
python = "^3.9"

[tool.poetry.dev-dependencies]

[build-system]
requires = ["poetry-core>=1.0.0"]
build-backend = "poetry.core.masonry.api"


Do you confirm generation? (yes/no) [yes] 

$ poetry env use 3.9.6
Creating virtualenv poet-practice-O7JUgyXW-py3.9 in /home/kumamoto/.cache/pypoetry/virtualenvs
Using virtualenv: /home/kumamoto/.cache/pypoetry/virtualenvs/poet-practice-O7JUgyXW-py3.9

$ cd ~/.cache/virtualenv
$ ls
envs.toml  poet-practice-O7JUgyXW-py3.9

$ cat envs.toml
[poet-practice-O7JUgyXW]
minor = "3.9"
patch = "3.9.6"

$ pyenv global 3.8.2
$ python --version
Python 3.8.2

$ poetry shell;
Spawning shell within /home/kumamoto/.cache/pypoetry/virtualenvs/poet-practice-O7JUgyXW-py3.9
. /home/kumamoto/.cache/pypoetry/virtualenvs/poet-practice-O7JUgyXW-py3.9/bin/activate
$ . /home/kumamoto/.cache/pypoetry/virtualenvs/poet-practice-O7JUgyXW-py3.9/bin/activate

-- 仮想環境に入ったあと
(poet-practice-O7JUgyXW-py3.9) $ python --version
Python 3.9.6

$ poetry add django@3.2
$ poetry add --dev mypy

--dev (-D): Add package as development dependency.
--path: The path to a dependency.
--optional : Add as an optional dependency.
--dry-run : Outputs the operations but will not execute anything (implicitly enables –verbose).
--lock : Do not perform install (only update the lockfile).

$ poetry install