Answers for "check all versions of ruby installed"

how to check ruby version

// Command line:
$ ruby -v

// Within irb type "RUBY_VERSION"
# => "2.4.1"

// If using RVM:
$ rvm current
# => ruby-2.4.1

manage ruby versions

$ 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