Why do I get a reboot instead of a shutdown?

Question

After two days of installation, strangely my Ubuntu machine is restarting instead of shutdown from both desktop GUI and command line.

sudo shutdown -h now
sudo halt (doesn't shutdown, instead freezes on boot screen Plymouth)

I had force shutdown by powering off the machine.

This is not happening all the times.

I have been using Ubuntu for 6 months and never experienced this kind of problem.

Answer 1

I faced the same issue after I installed Ubuntu 12.04 on a newly built machine. This answer on another post helped me resolve it: http://askubuntu.com/a/135568/40056

Hope that helps.

Answer 2

I had the same issue with new acer aspre v5 notebook. It has been solved by enabling laptop-mode as running

sudo apt-get install laptop-mode-tools.

Hope it will help you.

Answer 3

I have had exactly the same problem on my Acer V5-571G: the laptop shuts down, turns off its power LED, and then starts again after a few seconds. It occurs more often when working on battery.

The problem seems to arise from incorrect work of pm-utils. But if you write on into /sys/bus/*/devices/*/power/control, the kernel takes control over power management at the specified devices - and somehow this makes the hardware to shut down correctly.

So I have written a script:

#!/bin/bash

case "$1" in
  stop) for i in /sys/bus/*/devices/*/power/control ; do echo on > $i ; done 
  ;;
esac

exit 0

and to make it being executed every time before shutdown I've placed it under name K32power-control-on into /etc/rc0.d directory (don't forget to make the script executable, sudo chmod +x K32power-control-on). After that the laptop shuts down ok.

I think that there are only a few buses/devices which need to have 'on' value written to their power/control, so the list of devices in the script can be restricted, but I just didn't investigate further.

UPD: Here is a more refined solution of the same problem: http://www.pbehnke.com/main/node/11