For example, you can run unit tests using pytest against Python 2.7, switch to Python 3.8, and run the tests again - all with three easy commands. This makes running tests against different Python versions easy. $ pyenv local 2.7.17 $ python -version Python 2.7.17 $ pyenv local 3.5.9 $ python -version Python 3.5.9 With a simple command and without reinstalling anything, you can also switch which version of Python you’re using. $ python -version Python 3.6.10 $ python3.5 -version Python 3.5.9 $ python3.7 -version Python 3.7.6 $ python3.8 -version Python 3.8.1 $ python2.7 -version Python 2.7.17 Switch Python versions on command With pyenv, you can set a default version but easily refer to all five versions. pyenv makes it easy to use several versions.įor example, assume your project needs to run on five versions, Python 2.7, 3.5, 3.6, 3.7, and 3.8. While having a single Python version per project is a nice idea, it is probably more realistic that a single project will need to run on multiple Python versions. project2 project2$ python -version Python 3.8.1īoom! Use multiple Python versions at the same time $ cd project1 project1$ python -version Python 2.7.17 project1$ cd.

Simply change directories and the version of Python magically changes! If you have one project that uses Python 2.7.17 and another that’s on Python 3.8.1, switching directories between the projects automatically change your Python version too.

This is one of pyenv’s coolest party pieces. For a complete guide, see my story Zero to Hero: Set Up Your Mac for Software Development.īefore we get into the how of pyenv, what can you do with it? Switch Python versions by changing directories If your needs are simpler, see my story on The Right Way to Set Up Python on Your Mac. NOTE: This article discusses an advanced way to use Python where you need multiple versions.

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