Ever since installing Ruby I was puzzled as to why ri couldn’t find the basic documentation for built-in classes like
ri String would give me documentation for third-party additions to the
String class (for example, from Rails) but would show nothing about the standard methods.
I finally discovered the cause when playing with the command-line switches for ri and trying:
ri --site String
No ri documentation found in: /usr/local/share/ri/1.8/site Was rdoc run to create documentation? Installing Documentation ------------------------ 'ri' uses a database of documentation built by the RDoc utility. So, how do you install this documentation on your system? It depends on how you installed Ruby. _If you installed Ruby from source files_ (that is, if it some point you typed 'make' during the process :), you can install the RDoc documentation yourself. Just go back to the place where you have your Ruby source and type make install-doc You'll probably need to do this as a superuser, as the documentation is installed in the Ruby target tree (normally somewhere under +/usr/local+.
So I went back and did this as described in "Building and installing Ruby 1.8.5 on Mac OS X Tiger". Now
ri String works as expected.