跳到主要内容

pyenv instruction

· 阅读需 5 分钟

What is pyenv?​

pyenv is a Python version manager which is a tool to manage multiple Python versions.

pyenv-virtualenv is a tool to create isolated Python environments.

It allows pyenv and virtualenv to work together.

(pyenv-virtualenv 是一个可以将 pyenv 和 virtualenv 无缝连接起来的插件)[1]

Why use pyenv?​

When you develop multiple python projects, and these projects depends on different versions of Python or different Python libraries, you need this pyenv tool to manage Python versions or pyenv-virtualenv to manage different isolated environments with pyenv.

(当你在开发多个 Python 项目，且这些项目依赖了不同版本的 Python 或者不同库时，就会需要 pyenv 来管理 Python 版本或者使用 pyenv-virtualenv 来管理不同独立的 Python 环境)

How it works?​

Sample from https://github.com/pyenv/pyenv#how-it-works .

graph LR
cmd[Python-related command<br/>Like python, pip, ...] --> Shims
Shims --> pyenv

Simply to say, any Python-related command (like pip, python, pydoc...) will be executed by ~/.pyenv/shims/<command> first, then a proper Python version will be selected and the command will be executed

(简单来说，所有与 Python 相关的指令(比如 pip, python, pydoc...)都会被 ~/.pyenv/shims/<command> 执行，然后 pyenv 会选中一个合适的 Python 版本与环境来执行该指令).

Order of Python version selection​

  1. check PYENV_VERSION environment variable (could be set by pyenv shell). If it is set, use it. Otherwise, go to step 2.
  2. check .python-version file in the current directory (could be set by pyenv local). If it is set, use it. Otherwise, go to step 3.
  3. check .python-version file in all of the parent directories. If it is found, use it. Otherwise, go to step 4(找当前目录的所有父目录，看是否有 .python-version 文件。如果找到则使用，否则，转进到第 4 步).
  4. check $(pyenv root)/version file. If it is set, use it. Otherwise, use the default version defined by system.

Installation​

Sample from https://github.com/pyenv/pyenv#installation and https://github.com/pyenv/pyenv-virtualenv#installation .

For Linux/macOS​

End-to-end installation commands at my environments:

ENV-LAPTOP: Homebrew at macOS with zsh:

brew update
brew install pyenv
echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.zshrc
echo 'command -v pyenv >/dev/null || export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.zshrc
echo 'eval "$(pyenv init -)"' >> ~/.zshrc   # install `pyenv` into your shell as a shell function, enable shims and autocompletion
brew install pyenv-virtualenv
echo 'eval "$(pyenv virtualenv-init -)"' >> ~/.zshrc

ENV-WORK: Ubuntu 20.04 with zsh:

git clone https://github.com/pyenv/pyenv.git ~/.pyenv
echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.zshrc
echo 'command -v pyenv >/dev/null || export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.zshrc
echo 'eval "$(pyenv init -)"' >> ~/.zshrc   # install `pyenv` into your shell as a shell function, enable shims and autocompletion
git clone https://github.com/pyenv/pyenv-virtualenv.git .pyenv/plugins/pyenv-virtualenv
echo 'eval "$(pyenv virtualenv-init -)"' >> ~/.zshrc

For Windows​

pyenv does not support Windows yet. So I use pyenv-win instead.

Because pyenv is not supported at Windows, then pyenv-virtualenv is unavailable at Windows too. So I use virtualenv instead.

End-to-end installation commands at my environment:

ENV-PC: Windows 10 with PowerShell 7.2.1[4]:

git clone https://github.com/pyenv-win/pyenv-win.git "$HOME/.pyenv"
[System.Environment]::SetEnvironmentVariable('PYENV',$env:USERPROFILE + "\.pyenv\pyenv-win\","User")
[System.Environment]::SetEnvironmentVariable('PYENV_ROOT',$env:USERPROFILE + "\.pyenv\pyenv-win\","User")
[System.Environment]::SetEnvironmentVariable('PYENV_HOME',$env:USERPROFILE + "\.pyenv\pyenv-win\","User")
[System.Environment]::SetEnvironmentVariable('path', $env:USERPROFILE + "\.pyenv\pyenv-win\bin;" + $env:USERPROFILE + "\.pyenv\pyenv-win\shims;" + [System.Environment]::GetEnvironmentVariable('path', "User"),"User")

pyenv install <version>
pyenv global <version>
python -m pip install --user virtualenv

Usage​

pyenv/pyenv-win​

# check all installable Python versions
pyenv install --list
# install a specific Python version
pyenv install <version>
# use a specific Python version globally
pyenv global <version>
# use a specific Python version in current directory or in all of its subdirectories
pyenv local <version>
# use a specific Python version in the current shell
pyenv shell <version>

pyenv-virtualenv​

pyenv virtualenv <version> <env_name>
pyenv activate <env_name>
pyenv deactivate
# delete venv
pyenv virtualenv-delete <env_name>

virtualenv​

python -m venv <env_name>
source <env_name>/bin/activate  # for unix-like systems
.\<env_name>\Scripts\activate  # for Windows
deactivate
# delete venv
rm -rf <env_name>

Q & A​

Q: Error occurred: ERROR: The Python ssl extension was not compiled. Missing the OpenSSL lib?​

Run commands below[2]:

sudo apt-get update
sudo apt-get install make build-essential libssl-dev zlib1g-dev \
libbz2-dev libreadline-dev libsqlite3-dev wget curl llvm \
libncursesw5-dev xz-utils tk-dev libxml2-dev libxmlsec1-dev libffi-dev liblzma-dev

Q: Error occurred: ImportError: libpython3.8.so.1.0: cannot open shared object file: No such file or directory​

Run commands below[3]:

env PYTHON_CONFIGURE_OPTS="--enable-shared" pyenv install x.x.x
ls ~/.pyenv/version/x.x.x/lib

Q: Erorr occurred: ModuleNotFoundError: No module named '_lzma'​

Run commands below (MacOS):

brew install xz
pyenv uninstall <your_python_version>
pyenv install <your_python_version>

References​