(from [ruby-dev:40601] )

Try to login with too short passwords.

("a".."z").to_a.repeated_permutation(5).find {|s| login(s.join) }

====

Check ruby parser with doubtful strings.

%w(( ) $ ` ' | & =).repeated_permutation(5) do |s|
    begin; eval(p(s.join)); rescue Exception; end
end