I have just installed the RVM and I am reading The Well-Grounded Rubyist book. In the first chapter I am supposed to try ri String#upcase to view documentation on the upcase method, however I get a message saying:
Nothing known about String#upcase
I found some posts here on SO telling me that it probably is because RDoc is not installed. However I do not understand how to fix it.
I am using Mac OSX 10.6, and latest RVM. I have only installed 1.9.2, in addition to the standard Ruby interpreter which come along with the Developer kit from Apple.