curl -fsSL https://pyenv.run | bash

echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.zshrc
echo '[[ -d $PYENV_ROOT/bin ]] && export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.zshrc
echo 'eval "$(pyenv init - zsh)"' >> ~/.zshrc

$env.PYENV_ROOT = "~/.pyenv" | path expand
if (( $"($env.PYENV_ROOT)/bin" | path type ) == "dir") {
  $env.PATH = $env.PATH | prepend $"($env.PYENV_ROOT)/bin" }
$env.PATH = $env.PATH | prepend $"(pyenv root)/shims"

exec "$SHELL"

pyenv install 3.10.4

pyenv install 3.10
pyenv global 3.10

pyenv global 3.10.4

pyenv global 3.11 3.12

brew upgrade pyenv

brew uninstall pyenv
brew install pyenv --head

pyenv update

If you've installed Pyenv using Pyenv-installer or Git checkout, you can also upgrade your installation at any time using Git.

To upgrade to the latest development version of pyenv, use git pull:

cd $(pyenv root)
git pull

To upgrade to a specific release of Pyenv, check out the corresponding tag:

cd $(pyenv root)
git fetch
git tag
git checkout v0.1.0

The simplicity of pyenv makes it easy to temporarily disable it, or uninstall from the system.

1. To disable Pyenv managing your Python versions, simply remove the pyenv init invocations from your shell startup configuration. This will remove Pyenv shims directory from PATH, and future invocations like python will execute the system Python version, as it was before Pyenv.

   pyenv will still be accessible on the command line, but your Python apps won't be affected by version switching.

2. To completely uninstall Pyenv, remove all Pyenv configuration lines from your shell startup configuration, and then remove its root directory. This will delete all Python versions that were installed under the $(pyenv root)/versions/ directory:

   rm -rf $(pyenv root)

   If you've installed Pyenv using a package manager, as a final step, perform the Pyenv package removal. For instance, for Homebrew:

   brew uninstall pyenv
   

Pyenv provides a simple way to extend and customize its functionality with plugins -- as simple as creating a plugin directory and dropping a shell script on a certain subpath of it with whatever extra logic you need to be run at certain moments.

The main idea is that most things that you can put under $PYENV_ROOT/<whatever> you can also put under $PYENV_ROOT/plugins/your_plugin_name/<whatever>.

See Plugins on the wiki on how to install and use plugins as well as a catalog of some useful existing plugins for common needs.

See Authoring plugins on the wiki on writing your own plugins.

At a high level, pyenv intercepts Python commands using shim executables injected into your PATH, determines which Python version has been specified by your application, and passes your commands along to the correct Python installation.

When you run a command like python or pip, your shell (bash / zshrc / ...) searches through a list of directories to find an executable file with that name. This list of directories lives in an environment variable called PATH, with each directory in the list separated by a colon:

/usr/local/bin:/usr/bin:/bin

Directories in PATH are searched from left to right, so a matching executable in a directory at the beginning of the list takes precedence over another one at the end. In this example, the /usr/local/bin directory will be searched first, then /usr/bin, then /bin.

pyenv works by inserting a directory of shims at the front of your PATH:

$(pyenv root)/shims:/usr/local/bin:/usr/bin:/bin

Through a process called rehashing, pyenv maintains shims in that directory to match every Python command across every installed version of Python—python, pip, and so on.

Shims are lightweight executables that simply pass your command along to pyenv. So with pyenv installed, when you run, say, pip, your operating system will do the following:

• Search your PATH for an executable file named pip
• Find the pyenv shim named pip at the beginning of your PATH
• Run the shim named pip, which in turn passes the command along to pyenv

When you execute a shim, pyenv determines which Python version to use by reading it from the following sources, in this order:

1. The PYENV_VERSION environment variable (if specified). You can use the pyenv shell command to set this environment variable in your current shell session.

2. The application-specific .python-version file in the current directory (if present). You can modify the current directory's .python-version file with the pyenv local command.

3. The first .python-version file found (if any) by searching each parent directory, until reaching the root of your filesystem.

4. The global $(pyenv root)/version file. You can modify this file using the pyenv global command. If the global version file is not present, pyenv assumes you want to use the "system" Python (see below).

A special version name "system" means to use whatever Python is found on PATH after the shims PATH entry (in other words, whatever would be run if Pyenv shims weren't on PATH). Note that Pyenv considers those installations outside its control and does not attempt to inspect or distinguish them in any way. So e.g. if you are on MacOS and have OS-bundled Python 3.8.9 and Homebrew-installed Python 3.9.12 and 3.10.2 -- for Pyenv, this is still a single "system" version, and whichever of those is first on PATH under the executable name you specified will be run.

NOTE: You can activate multiple versions at the same time, including multiple versions of Python2 or Python3 simultaneously. This allows for parallel usage of Python2 and Python3, and is required with tools like tox. For example, to instruct Pyenv to first use your system Python and Python3 (which are e.g. 2.7.9 and 3.4.2) but also have Python 3.3.6, 3.2.1, and 2.5.2 available, you first pyenv install the missing versions, then set pyenv global system 3.3.6 3.2.1 2.5.2. Then you'll be able to invoke any of those versions with an appropriate pythonX or pythonX.Y name. You can also specify multiple versions in a .python-version file by hand, separated by newlines. Lines starting with a # are ignored.

pyenv which <command> displays which real executable would be run when you invoke <command> via a shim. E.g. if you have 3.3.6, 3.2.1 and 2.5.2 installed of which 3.3.6 and 2.5.2 are selected and your system Python is 3.2.5, pyenv which python2.5 should display $(pyenv root)/versions/2.5.2/bin/python2.5, pyenv which python3 -- $(pyenv root)/versions/3.3.6/bin/python3 and pyenv which python3.2 -- path to your system Python due to the fall-through (see below).

Shims also fall through to anything further on PATH if the corresponding executable is not present in any of the selected Python installations. This allows you to use any programs installed elsewhere on the system as long as they are not shadowed by a selected Python installation.

Once pyenv has determined which version of Python your application has specified, it passes the command along to the corresponding Python installation.

Each Python version is installed into its own directory under $(pyenv root)/versions.

For example, you might have these versions installed:

• $(pyenv root)/versions/2.7.8/
• $(pyenv root)/versions/3.4.2/
• $(pyenv root)/versions/pypy-2.4.0/

As far as Pyenv is concerned, version names are simply directories under $(pyenv root)/versions.

Skip this section unless you must know what every line in your shell profile is doing.

Also see the Environment variables section for the environment variables that control Pyenv's behavior.

pyenv init is the only command that crosses the line of loading extra commands into your shell. Coming from RVM, some of you might be opposed to this idea. Here's what eval "$(pyenv init -)" actually does:

1. Finds current shell. pyenv init figures out what shell you are using, as the exact commands of eval "$(pyenv init -)" vary depending on shell. Specifying which shell you are using (e.g. eval "$(pyenv init - bash)") is preferred, because it reduces launch time significantly.

2. Sets up the shims path. This is what allows Pyenv to intercept and redirect invocations of python, pip etc. transparently. It prepends $(pyenv root)/shims to your $PATH. It also deletes any other instances of $(pyenv root)/shims on PATH which allows to invoke eval "$(pyenv init -)" multiple times without getting duplicate PATH entries.

3. Installs autocompletion. This is entirely optional but pretty useful. Sourcing <pyenv installation prefix>/completions/pyenv.bash will set that up. There are also completions for Zsh and Fish.

4. Rehashes shims. From time to time you'll need to rebuild your shim files. Doing this on init makes sure everything is up to date. You can always run pyenv rehash manually.

5. Installs pyenv into the current shell as a shell function. This bit is also optional, but allows pyenv and plugins to change variables in your current shell. This is required for some commands like pyenv shell to work. The sh dispatcher doesn't do anything crazy like override cd or hack your shell prompt, but if for some reason you need pyenv to be a real script rather than a shell function, you can safely skip it.

eval "$(pyenv init --path)" only does items 2 and 4.

To see exactly what happens under the hood for yourself, run pyenv init - or pyenv init --path.

eval "$(pyenv init -)" is supposed to run at any interactive shell's startup (including nested shells -- e.g. those invoked from editors) so that you get completion and convenience shell functions.

eval "$(pyenv init --path)" can be used instead of eval "$(pyenv init -)" to just enable shims, without shell integration. It can also be used to bump shims to the front of PATH after some other logic has prepended stuff to PATH that may shadow Pyenv's shims.

• In particular, in Debian-based distributions, the stock ~/.profile prepends per-user bin directories to PATH after having sourced ~/.bashrc. This necessitates appending a pyenv init call to ~/.profile as well as ~/.bashrc in these distributions because the system's Pip places executables for modules installed by a non-root user into those per-user bin directories.

If you don't want to use pyenv init and shims, you can still benefit from pyenv's ability to install Python versions for you. Just run pyenv install and you will find versions installed in $(pyenv root)/versions.

You can manually execute or symlink them as required, or you can use pyenv exec <command> whenever you want <command> to be affected by Pyenv's version selection as currently configured.

pyenv exec works by prepending $(pyenv root)/versions/<selected version>/bin to PATH in the <command>'s environment, the same as what e.g. RVM does.

You can affect how Pyenv operates with the following environment variables:

See also Special environment variables in Python-Build's README for environment variables that can be used to customize the build.

The pyenv source code is hosted on GitHub. It's clean, modular, and easy to understand, even if you're not a shell hacker.

Tests are executed using Bats:

bats test
bats/test/<file>.bats

Feel free to submit pull requests and file bugs on the issue tracker.

See CONTRIBUTING.md for more details on submitting changes.

See CHANGELOG.md.

The MIT License