Getting ri working for built-in classesEdit

Ever since installing Ruby I was puzzled as to why ri couldn’t find the basic documentation for built-in classes like String. Typing 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

This yielded:

No ri documentation found in:

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

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.

See also