`man irb` claims I can start irb with

 % ruby -r irb -e0

but nothing happens.  Turning on warnings, I get:

 % ruby -w -r irb -e0
 /usr/local/pkgs/ruby/lib/ruby/1.7/irb/context.rb:129: warning: method redefined; discarding old irb_name
 /usr/local/pkgs/ruby/lib/ruby/1.7/irb/context.rb:200: warning: method redefined; discarding old math_mode=
 /usr/local/pkgs/ruby/lib/ruby/1.7/irb/context.rb:214: warning: method redefined; discarding old use_readline=
 -e:1: warning: useless use of a literal in void context

Confused,
-- 
Bil Kleb
NASA Langley Research Center
Hampton, Virginia, USA