I am using different programming languages like C#, Java, Node.js etc and need to manage runtime versions in my local. So, I like to use runtime version managers.

For example, there are some runtime version managers in Node.js community like nvm or n.

Let's say I work for one Node.js project in dev machine with Node v8.0.0 but other project needs Node v6.0.0

In order to handle, different versions in same machine, we may use runtime version managers.

I just want to find a way to switch between different Python runtime version so that found pyenv runtime version manager.

Pyenv is a simple, powerful and cross-platform tool for managing multiple versions of Python on a single machine. It is very useful when you need to switch between different Python versions for different projects, or when different applications on your system require different Python versions.

So, we can install, uninstall, list or switch between different versions.

Pyenv installation

Click pyenv link for more detailed installation.

Installing pyenv with Homebrew

First, ensure that you have Homebrew installed in your system. Homebrew is a package manager for Mac OS. So if you want to learn more details about it, visit my post.

Homebrew package manager for Mac OS and Linux

Run the following commands in your terminal. But, just copy commands without $ sign.

$ brew update
$ brew install pyenv

Setting PATH

Checking shell

output of echo $SHELL can be bash, zsh or fish

$ echo $SHELL

/usr/local/bin/bash

# OR

/bin/zsh

Run the following command for bash, zsh, etc configuration.

$ echo 'eval "$(pyenv init -)"' >> ~/.zshrc

and restart your terminal manually or run the following command to restart automatically.

$ exec "$SHELL"

Upgrading pyenv

$ brew upgrade pyenv

Uninstall pyenv

$ rm -rf $(pyenv root)
$ brew uninstall pyenv

Pyenv commands

List all Python versions installed in system

$ pyenv versions

  system
  3.7.3
* 3.8.2 (set by /Users/kenanhancer/.pyenv/version)

Show current active Python version in system

$ pyenv version

3.8.2 (set by /Users/kenanhancer/.pyenv/version)

List all available Python versions

Pyenv will show very long list but I just took some part of it. (still many part of list is here 🙂 )

$ brew update && brew upgrade pyenv

$ pyenv install --list

Available versions:
  2.1.3
  2.2.3
  2.3.7
  2.4.0
  2.4.1
  2.4.2
  2.4.3
  2.4.4
  2.4.5
  2.4.6
  2.5.0
  2.5.1
  2.5.2
  2.5.3
  2.5.4
  2.5.5
  2.5.6
  2.6.6
  2.6.7
  2.6.8
  2.6.9
  2.7.0
  2.7-dev
  2.7.1
  2.7.2
  2.7.3
  2.7.4
  2.7.5
  2.7.6
  2.7.7
  2.7.8
  2.7.9
  2.7.10
  2.7.11
  2.7.12
  2.7.13
  2.7.14
  2.7.15
  2.7.16
  2.7.17
  3.0.1
  3.1.0
  3.1.1
  3.1.2
  3.1.3
  3.1.4
  3.1.5
  3.2.0
  3.2.1
  3.2.2
  3.2.3
  3.2.4
  3.2.5
  3.2.6
  3.3.0
  3.3.1
  3.3.2
  3.3.3
  3.3.4
  3.3.5
  3.3.6
  3.3.7
  3.4.0
  3.4-dev
  3.4.1
  3.4.2
  3.4.3
  3.4.4
  3.4.5
  3.4.6
  3.4.7
  3.4.8
  3.4.9
  3.4.10
  3.5.0
  3.5-dev
  3.5.1
  3.5.2
  3.5.3
  3.5.4
  3.5.5
  3.5.6
  3.5.7
  3.5.8
  3.5.9
  3.6.0
  3.6-dev
  3.6.1
  3.6.2
  3.6.3
  3.6.4
  3.6.5
  3.6.6
  3.6.7
  3.6.8
  3.6.9
  3.6.10
  3.7.0
  3.7-dev
  3.7.1
  3.7.2
  3.7.3
  3.7.4
  3.7.5
  3.7.6
  3.7.7
  3.8.0
  3.8-dev
  3.8.1
  3.8.2
  3.9.0a5
  3.9-dev
  activepython-2.7.14
  activepython-3.5.4
  activepython-3.6.0
  anaconda-1.4.0
  anaconda-1.5.0
  anaconda-1.5.1
  anaconda-1.6.0
  anaconda-1.6.1
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Filter Python versions with grep

Way 1

This command will list all available Python versions starting with '3.' The ^[[:space:]]*3\. pattern matches lines that start with any number of spaces, followed by '3.'

$ pyenv install --list | grep '^[[:space:]]*3\.'

Way 2

We can use grep with tr to trim the leading spaces. The tr -d " " command deletes (-d) all spaces from the input. Then grep can find lines starting with '3.' without having to worry about leading spaces.

$ pyenv install -l | tr -d " " | grep '^3\.'

Filter Python versions with awk

This command lists all available Python versions starting with '3.'. The /^ *3\./ pattern matches lines that start with any number of spaces (indicated by the * after the space), followed by '3.'.

$ pyenv install -l | awk '/^ *3\./'

Installing Python versions

$ pyenv install 3.7.3

$ pyenv install 3.8.2

Setting global default version in your system

$ pyenv global 3.7.3

Go back to the system version of Python as the default

If you want to go back to your system default Python version, run the following code.

$ pyenv global system

Switch between Python versions

$ pyenv shell 3.7.3

$ pyenv local 3.7.5

$ pyenv global 3.10.4

Checking Python version

$ pyenv version

3.7.3 (set by /Users/kenanhancer/.pyenv/version)

or

$ python --version

Python 3.7.3

Checking Python path

$ pyenv which python

/Users/kenanhancer/.pyenv/versions/3.7.3/bin/python

$ which python

/Users/kenanhancer/.pyenv/shims/python

Checking Pip version

$ pip --version

pip 19.0.3 from /Users/kenanhancer/.pyenv/versions/3.7.3/lib/python3.7/site-packages/pip (python 3.7)

Checking Pip path

$ pyenv which pip

/Users/kenanhancer/.pyenv/versions/test31-3.9.17/bin/pip

$ which pip

/Users/kenanhancer/.pyenv/shims/pip

Updating PIP

$ pip install --upgrade pip

Requirement already up-to-date: pip in ./.pyenv/versions/3.8.2/lib/python3.8/site-packages (20.1)

What is PIP?

PIP is the standard package manager for Python packages, or modules like npm(Node Package Manager in Node.js community)

With pip, you can install packages from the Python Package Index (PyPI) and other indexes. PyPI is a repository of software for the Python programming language and hosts thousands of third-party modules that make Python a more powerful language.

Modules are Python code libraries you can include in your project.

If you have Python version 3.4 or later, PIP is included by default.