This is the final step, it's time to install your new Ruby interpreter. Run the install make target to install Ruby. Since Ruby will be installed to /usr/local, you will need to run this command as root or with sudo.
$ sudo make install
You're done. You can now run Ruby scripts with the ruby19 command, access IRB with irb19 and the Rubygems for Ruby 1.9.1 with gem19.