Who needs Ruby 2.0 right now? Not a lot.
But if for some odd reason, you need really it and have encountered some issues, I hope this helps you move on and get beyond this gibberish stuff.
There are a lot of guides written. Those may work. But if you get something like this:
Error running 'make', please read /Users/katz/.rvm/log/ruby-2.0.0-rc1/make.log
It won't compile without some flags.
If you use homebrew and Mac OS X, great! All you need is to follow this:
brew install openssl rvm get head CC=clang rvm install 2.0.0 -C --enable-shared, --with-openssl-dir=/usr/local
I found these commands necessary as the above commands no longer work:
rvm get head --autolibs=3 rvm requirements rvm install ruby-2.0.0
Similarly, in Ubuntu. This worked:
sudo apt-get install openssl rvm get head rvm install 2.0.0 -C --enable-shared, --with-openssl-dir=/usr/local