OS X 10.11.5. I'm learning Ruby and followed Ryan Bigg's post to install Ruby and Rails using chruby and ruby-install. After using vim for a few small programs I looked for a more productive environment. I installed RubyMine and like it, but RubyMine doesn't support chruby. JetBrains tech support recommends I use rbenv/RVM.
I selected chruby because the blog post didn't have sudo. I'm new to OS X and don't yet understand sudo and SIP.
Should I use rbenv or RVM?
sudo is just a command that executes the command following it as root. This results in files created by those commands being owned by root, and being uneditable and undeletable by your user account.
rvm vs. rbenv is a matter of personal preference -- my preference is rvm. I find it very easy to use and rich in functionality. You don't need to install it using sudo -- in fact, I prefer not to. It will install everything in a ~/.rvm directory, and requires some minor modification to your startup scripts, which it can usually do automatically as part of the installation. Google install rvm for clear instructions about how to install it.