Getting Ruby

Install the ruby version manager:

chruby – manages installed ruby versions
ruby-install – install a version

With:

 $ brew install chruby ruby-install

Then, install the latest ruby version:

$ ruby-install ruby

Change to a given version:

$ chruby ruby-3
$ ruby -v

# Note: 'chruby' was only found on my system after adding it to the zsh profile:

# add chruby to shell with ruby v3 as default version
source /usr/local/opt/chruby/share/chruby/chruby.sh
chruby ruby-3

Getting Jekyll

Install the gems:

$ cd <project-root>
gem install bundler
bundler install

Run the project using bundler, because it avoids gem conflicts:

bundle exec jekyll build
bundle exec jekyll serve