How to build an environment for any version of Ruby using rbenv

This article will show you how to build any version of Ruby environment using rbenv.

What is rbenv?

rbenv ** is a tool ** that manages different versions of ruby collectively.

By using rbenv, you can centrally manage different versions of ruby, In addition, you can switch to any version at any time. You can use Ruby with any version.

For example, when I am advancing self-learning, for example, some teaching materials say that I use ruby 2.5.2. If you are instructed to use ruby 2.7.0 in another material, the difference between versions may cause an error and get stuck.

By using rbenv, you can always use your favorite version. At the very least, errors due to differences between versions can be suppressed.

rbenv setup

Now let's actually set up rbenv.

Install rbenv

rbenv can be installed with HomeBrew. Hit the following command.

$ brew install rbenv

Initial setting of rbenv

After installing rbenv, enter rbenv init for initial setup.

$ rbenv init

When you enter and press Enter, the following instructions will be displayed. Follow the instructions. Here we are telling you to add the line eval ~ to ~ / .bash_profile.

$ rbenv init
# Load rbenv automatically by appending
# the following to ~/.bash_profile:

eval "$(rbenv init -)"

Open .bash_profile with the vi command and add eval ~ to the end.

• If you are not familiar with operations such as vim, you can edit .bash_profile directly though it is a hidden file.

$ vi ~/.bash_profile

When you have finished saving, quit the terminal and reopen it. You can now use rbenv from anywhere.

Testing rbenv

Then run the following command to check if rbenv is working properly. (Introduced on the official website of rbenv))

$ curl -fsSL https://github.com/rbenv/rbenv-installer/raw/master/bin/rbenv-doctor | bash
Checking for `rbenv' in PATH: /usr/local/bin/rbenv
Checking for rbenv shims in PATH: OK
Checking `rbenv install' support: /usr/local/bin/rbenv-install (ruby-build 20170523)
Counting installed Ruby versions: none
  There aren't any Ruby versions installed under `~/.rbenv/versions'.
  You can install Ruby versions like so: rbenv install 2.2.4
Checking RubyGems settings: OK
Auditing installed plugins: OK

If everything is OK, as in the example above, rbenv is ready.

Ruby setup

Now that you can version control Ruby with rbenv, let's install Ruby.

Install Ruby with rbenv

Enter rbenv install xxxx to install Ruby. This time, I will install the latest stable version, ruby 2.7.0, at the time of writing.

$ rbenv install 2.7.0

Check the list of installed Ruby

Enter rbenv version to see the installed version.

$ rbenv versions
  system
* 2.5.1 (set by /Users/xxxxxx/.rbenv/version)
  2.6.3
  2.7.0

The version marked with * is the version of ruby you are currently using. This means that 2.7.0 is just installed and hasn't switched yet.

• The above example is when another version is already installed with rbenv.

Version switching

Use the rbenv global command to switch to the installed 2.7.0.

$ rbenv global 2.7.0

Enter ruby -v to see which Ruby version you are using.

$ ruby -v
ruby 2.7.0p0 (2019-12-25 revision 647ee6f091) [x86_64-darwin19]

Since 2.7.0 is displayed, I was able to successfully install ruby 2.7.0 and build the environment.