signal_tester.rb

#!/usr/bin/env ruby                                                                     

Signal.list.each do |signal, number|
  begin
    print "trapping % -6s ..." % signal
    Signal.trap(signal) do
      puts 'caught ' + signal
      exit
    end
    puts 'ok.'
  rescue
    puts 'reserved.'
  end
end

puts 'Enter endless loop.'
loop { sleep 1 }