#!/usr/bin/env ruby

# Run only run one daemon at a time.
pid_file = "/tmp/#{File.basename($PROGRAM_NAME)}.pid"
if File.exists?(pid_file)
  puts "PID file exists already!" 
  exit
end

# Daemonize
if RUBY_VERSION < "1.9"
  exit if fork
  Process.setsid
  exit if fork
  STDIN.reopen "/dev/null"
  STDOUT.reopen "/dev/null", "a"
  STDERR.reopen "/dev/null", "a"
else
  Process.daemon
end

# Forked childs write a PID file on startup and remove it at exit.
File.open(pid_file, 'w') { |f| f.puts(Process.pid) }
at_exit { File.delete(pid_file) }

# Finally run the lazy daemon
loop { sleep 1 }