Although many distros come with a system Ruby installed or a repository version, we suggest using a version manager such as rbenv or RVM. This will ensure you have an up to date Ruby version and a clean environment separated from your system Ruby.

The instructions for installing via rbenv on Ubuntu are provided below (since that is what we generally use).

Installing rbenv is a manual process, which is sort of nice because it is so minimal!

You will need these packages to build Gems:

sudo apt install autoconf bison build-essential libssl-dev libyaml-dev libreadline-dev zlib1g-dev libncurses5-dev libffi-dev libgdbm-dev 

Install and then close your terminal.

(this is based on the suggested build environment from ruby-build, slightly updated and tweaked for simplicity)

Using the Basic Git Checkout method to install rbenv is the simpliest and most up to date.

Open a terminal and clone rbenv into your home directory:

git clone https://github.com/rbenv/rbenv.git ~/.rbenv 

Then run the init function to set it up:

~/.rbenv/bin/rbenv init 

Close terminal and open a new one.

Clone ruby-build into the rbenv plugins directory:

git clone https://github.com/rbenv/ruby-build.git "$(rbenv root)"/plugins/ruby-build 

Check the Ruby download page to find the latest stable version or your project requirements to find your desired Ruby version number.

Check rbenv install -l to get a list of available stable versions.

Use rbenv install + version number, e.g.:

rbenv install 3.4.1 

This can take awhile since ruby-build will download and build from source.

Once complete, set the version you want to use:

rbenv global 3.4.1 

Now, ruby -v should report what you just set.

To avoid possible issues, we suggest you update Ruby Gem at this time. Gem is a tool to install Ruby Gems packages on your system. It comes with your Ruby, but may be out of date in the installer. To update, type the command: gem update --system

Since you installed the tools using git, to update rbenv and ruby-build you simply git pull the most recent master branch code.

cd ~/.rbenv && git pull cd "$(rbenv root)"/plugins/ruby-build && git pull 

Note: the list of available Ruby versions (rbenv install -l) is NOT automatically updated. So you should periodically update ruby-build following the git pull method above (i.e. cd ~/.rbenv/plugins/ruby-build && git pull).

Once rbenv is updated, you can install a new ruby version following the steps above.

In any existing projects, you will want to delete the "Gemfile.lock" file (since it is based on your old versions).

{:.alert .alert-yellow} Note: there is technically an Ubuntu package available so you can use sudo apt install rbenv ruby-build. Unfortunately ruby-build is super out of date, so it will only list very out-of-date versions of Ruby to install. This is not a good install method!