master.rb

puts $$
children = []
list = [1,2]
list.each do |i|
  pid = fork {
    puts i
    loop do
      print '.'
      sleep 0.5
    end
  }
  Process.detach(pid)
  children << pid
end
trap("INT") { 
  children.each {|i| Process.kill("INT", i) }
  exit
}
list = nil
Process.waitall