blink.rb

def main
  message = "THIS IS IMPORTANT"
  red_message = color(31, message)
  puts "", red_message, ""
  10.times do
    print restore_pos(up_line(2) + erase_line)
    sleep 0.5
    print restore_pos(up_line(2) + red_message)
    sleep 0.5
  end
end

def color(code, str)
  csi("#{code}m") + str + csi("0m")
end

def restore_pos(str)
  csi("s") + str + csi("u")
end

def up_line(n)
  csi("#{n}F")
end

def erase_line
  csi("K")
end

def csi(x)
  "\e[#{x}"
end

trap(:INT) { exit }

main