Quick script to check the laptop lid state (Surface Pro 3, Ubuntu 18.04), and trigger hibernate

check_lid.rb

#!/usr/bin/env ruby
#
# Disable lid control in /etc/systemd/logind.conf, for example:
#
# [Login]
# HandlePowerKey=hibernate
# HandleSuspendKey=ignore
# HandleLidSwitch=ignore

cnt = 0
while true
  val = `cat /proc/acpi/button/lid/LID0/state`
  if (val.include?("closed")) then
    puts " - closed!"
    cnt = cnt + 1
    if (cnt > 5) then
      cnt = 0
      puts "LID triggered hibernate!"
      `systemctl hibernate`
      `sleep 30`
    end
  else
    puts " - NOT closed!"
    cnt = 0
  end
  `sleep 5`
end