Upgrading Ruby Version Using rbenv

1. Install rbenv (see https://github.com/rbenv/rbenv)

2. Check available 2.6.x versions:

   $ egrep "^\s+2\.6\.\d+$" <(rbenv install -l) | tail -1

   If the version is not listed, then you might need to update the ruby-build:

   $ brew upgrade ruby-build
   

   or

   $ cd ~/.rbenv
   $ git pull
   $ cd plugins/ruby-build
   $ git pull
   

3. Install Ruby:

   $ rbenv install 2.6.6

4. Check all versions:

   $ rbenv versions

5. Set it as global and/or local:

   $ rbenv global 2.6.6

   $ rbenv local 2.6.6

6. Need to install bundler for each version of Ruby:

   $ gem install bundle

7. Need to run bundle install for your existing app:

   $ cd /path/to/psulib_blacklight
   $ bundle install