From http://tecadmin.net/install-ruby-2-0-on-centos-rhel/

RVMinstall.rb

Searching for binary rubies, this might take some time.
No binary rubies available for: centos/6/i386/ruby-2.0.0-p451.
Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies.
Checking requirements for centos.
Requirements installation successful.
Installing Ruby from source to: /usr/local/rvm/rubies/ruby-2.0.0-p451, this may take a while depending on your cpu(s)...
ruby-2.0.0-p451 - #downloading ruby-2.0.0-p451, this may take a while depending on your connection...
** Resuming transfer from byte position 24576
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 10.2M  100 10.2M    0     0   188k      0  0:00:55  0:00:55 --:--:--  414k
ruby-2.0.0-p451 - #extracting ruby-2.0.0-p451 to /usr/local/rvm/src/ruby-2.0.0-p451...
ruby-2.0.0-p451 - #applying patch /usr/local/rvm/patches/ruby/changeset_r45225.diff.
ruby-2.0.0-p451 - #applying patch /usr/local/rvm/patches/ruby/changeset_r45240.diff.
ruby-2.0.0-p451 - #applying patch /usr/local/rvm/patches/ruby/ssl_no_ec2m.patch.
ruby-2.0.0-p451 - #configuring..................................................
ruby-2.0.0-p451 - #post-configuration.
ruby-2.0.0-p451 - #compiling............................................................................
ruby-2.0.0-p451 - #installing.............................
ruby-2.0.0-p451 - #making binaries executable..
ruby-2.0.0-p451 - #downloading rubygems-2.2.2
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  404k  100  404k    0     0  96653      0  0:00:04  0:00:04 --:--:--  136k
No checksum for downloaded archive, recording checksum in user configuration.
ruby-2.0.0-p451 - #extracting rubygems-2.2.2...
ruby-2.0.0-p451 - #removing old rubygems.........
ruby-2.0.0-p451 - #installing rubygems-2.2.2...............
ruby-2.0.0-p451 - #gemset created /usr/local/rvm/gems/ruby-2.0.0-p451@global
ruby-2.0.0-p451 - #importing gemset /usr/local/rvm/gemsets/global.gems.....................................
ruby-2.0.0-p451 - #generating global wrappers.........
ruby-2.0.0-p451 - #gemset created /usr/local/rvm/gems/ruby-2.0.0-p451
ruby-2.0.0-p451 - #importing gemsetfile /usr/local/rvm/gemsets/default.gems evaluated to empty gem list
ruby-2.0.0-p451 - #generating default wrappers.........
ruby-2.0.0-p451 - #adjusting #shebangs for (gem irb erb ri rdoc testrb rake).
Install of ruby-2.0.0-p451 - #complete
Please be aware that you just installed a ruby that requires 2 patches just to be compiled on an up to date linux system.
This may have known and unaccounted for security vulnerabilities.
Please consider upgrading to ruby-2.1.1 which will have all of the latest security patches.
Ruby was built without documentation, to build it run: rvm docs generate-ri