init.rb

#!/usr/bin/env ruby

require 'logger'
require 'timeout'

def trap_signal(s)
  Signal.trap s do
    Signal.trap('INT', 'IGNORE')
    Signal.trap('TERM', 'IGNORE')
    raise Interrupt
  end
end

class Runit
  def run
    @pid = Process.spawn "/usr/bin/runsvdir -P /etc/service 'log:#{'.' * 395}'"
    if $stdout.isatty
      wait_to_die Process.spawn ('/bin/bash')
    else
      @status = wait_to_die
    end
  end

  def stop
    `/usr/bin/sv down /etc/service/*`
    kill_self
    kill_children
  end

  private

  def kill(pid, signal = 'TERM')
    Process.kill(signal, pid)
  rescue Errno::ESRCH
  end

  def kill_self
    kill(@pid)
    Timeout::timeout(5) { wait_to_die }
  rescue Timeout::Error
    kill(@pid, 'KILL')
    wait_to_die
  end

  def kill_children
    kill(-1)
    Timeout::timeout(5) { Process.waitpid(-1) and redo }
  rescue Timeout::Error
    kill(-1, 'KILL')
  rescue Errno::ECHILD
  end

  def wait_to_die(pid = @pid)
    while true do
      break $?.exitstatus if Process.waitpid(-1) == pid
    end
  rescue Errno::ECHILD
    '??'
  end
end

trap_signal('INT')
trap_signal('TERM')

runit = Runit.new
log = Logger.new(STDOUT)

begin
  log.info "Exited with status #{runit.run}"
rescue Interrupt
  log.warn "Keyboard interrupt, halting"
ensure
  runit.stop
end

nice

nicer