find file.rb

require 'find'

puts "input your dir:"
dir     = gets.chomp

puts "input your pattern:"
pattern = gets.chomp
Find.find(dir) do |file|
  puts file if File.file?(file) && File.basename(file) =~/#{pattern}/
end

rake search file demo.rb

namespace :file do
  desc "rake search file demo"
  task :search do
    Dir.chdir ENV["dir"]||"."
    FileList[ENV["pattern"]].each do |file|
      p file
    end
  end
end
#C:\workspace\eldorado>rake file:search pattern=**/*.rb