background tasks in Ruby e linux

class BackgroundJob
 
  def initialize(cmd)
    @pid = fork do
     # this code is run in the child process
     # you can do anything here, like changing current directory or reopening STDOUT
     exec cmd
    end
  end
 
  def stop!
    # kill it (other signals than TERM may be used, depending on the program you want
    # to kill. The signal KILL will always work but the process won't be allowed
    # to cleanup anything)
    Process.kill "TERM", @pid
    # you have to wait for its termination, otherwise it will become a zombie process
    # (or you can use Process.detach)
    Process.wait @pid
  end
 
end 

    wg = BackgroundJob.new 'wget http://www.google.it'
    sleep 10
    wg.stop!