Setting up and using RBENV on macOS

Rbenv is a great tool for setting up Ruby environments. Different applications could require different versions of Ruby and Rails so using Rbenv to manage this makes things a lot easier and ensures pulling your hair out remains at a minimum.

Installing Homebrew

Homebrew is an excellent package manager for macOS that simplifies installing and managing applications and utilities. More info about Homebrew can be found on their site here. Running the following command from the terminal will install Homebrew.

/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

This will then give you the brew command you can use in the terminal. Some useful commands for brew.

brew update #Fetch the newest version of Homebrew and its formulas
brew install <PACKAGE NAME> #Installs the specified package. If its not found try brew update first.
brew list #List installed packages
brew doctor #Checks for problems and possible solutions

You can see the full list of commands here

Installing Rbenv using Homebrew

An important note from the Rbenv github page.

Compatibility note: rbenv is incompatible with RVM. Please make sure to fully uninstall RVM and remove any references to it from your shell initialization files before installing rbenv.

So make sure you don’t do what Donny Don’t does!

First make sure that your Homebrew is up to date by running

brew update

Then you’ll need to run the following command to install Rbenv

brew install rbenv

When this completes finally you’ll need to run

rbenv init

which initialises rbenv. To be able to install difference versions of ruby we’ll also need to install another package called ruby-build. This provides the rbenv install command. To install ruby-build run the following command in the terminal.

brew install ruby-build

Installing a Ruby version

Now we are ready to install a new version of Ruby using rbenv. To list the available versions for installation run the following command.

rbenv install -l

It will give you a long list of options that will look something like this

2.2.5
2.2.6
2.3.0-dev
2.3.0-preview1
2.3.0-preview2
2.3.0
2.3.1
2.3.2
2.3.3
2.4.0-dev
2.4.0-preview1
2.4.0-preview2
2.4.0-preview3
2.4.0-rc1
2.4.0
2.4.1

We’ll install the latest stable version from this list which is 2.4.1 so to do that we’ll run this command

rbenv install 2.4.1

This will then download and install that version of Ruby. The installation process will be the same for any version of Ruby that you choose. This may take a while so be patient. Maybe go out and fly a kite while you’re waiting.

Installing gems

When the version of Ruby you selected is finished installed you’ll need to install bundler to manage gems. To do this run the following command to install bundler. You’ll more than likely need to do this for each version of Ruby you install.

gem install bundler

You can then install gems as you would normally.

Useful Rbenv commands

rbenv versions #Lists all the installed versions of Ruby
rbenv version #Lists the currently active Ruby version
rbenv global <RUBY VERSION> #Sets the version of Ruby to use globally. This can be overridden in specific applications by using a .ruby-version file containing the desired version to use instead.