If you would like to use the newest Ruby, make sure you use the correct package name, or use the tools described further below instead.
ruby-build can also be used as a standalone program without rbenv.
It is available for OS X, Linux, and other UNIX-like operating systems.
Certain members in the Ruby community feel very strongly that you should never use a package manager to install Ruby and that you should use tools instead.
While the full list of pros and cons is outside of the scope of this page, the most basic reason is that most package managers have older versions of Ruby in their official repositories.
Uru is a lightweight, multi-platform command line tool that helps you to use multiple Rubies on OS X, Linux, or Windows systems.