ri 1.8.1-8 (ia64 binary) in ubuntu hoary

Ruby Interactive reference (ri)
 ri is a command line tool that displays descriptions of built-in Ruby
 methods, classes, and modules. For methods, it shows you the calling
 sequence and a description. For classes and modules, it shows a synopsis
 along with a list of the methods the class or module implements.
 .
 This package is a dependency package, which depends on Debian's default
 Ruby version (currently 1.8.x).