trial.rb

require 'rubygems'
require 'rev'

class SomeWatcher < Rev::StatWatcher
  def initialize(watch_path)
    super(watch_path)
    puts "watching #{path}"
  end

  def on_change
    puts "Change"
  end
end

l = Rev::Loop.new :backend => :kqueue
w = SomeWatcher.new('./trial.rb')

w.attach l

l.run