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I'm dual booting win7 and Ubuntu(12.04 LTS) but when I'm shutting down/restarting Ubuntu to switch OS I only get to the log-out screen. I can turn the computer off with the power button but I would like to be able to do it the normal way.

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I had the same problem with machines authenticating via Kerberos.

You should see a log entry in /var/log/syslog like this

WARNING: Unable to stop system: Authorization is required

It's the polkit daemon that is preventing this. The file


is controlling the behavior of this. There are 4 entrys


And the values for each entry


They mean shutting down and rebooting the system and shutdown/reboot when others user are logged in too (to check type who in terminal). allow_inactive means generally remote sessions (SSH, VNC), allow_active are direct logins via TTYs or X. So you have to decide who should be able to reboot/shutdown your system.

By default a local logged in user can reboot/shutdown the system, but when there are other sessions, for example an open SSH session and you try to reboot the system, you will be logged out instead. Then you have to set in entries org.freedesktop.consolekit.system.stop-multiple-users and org.freedesktop.consolekit.system.restart-multiple-users the value allow_active to yes: <allow_active>yes</allow_active>.

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The file


will be overwritten when policykit is updated. You can add local configuration somewhere under /etc/polkit-1/localauthority.

I added a file /etc/polkit-1/localauthority/50-local/50-com.[my name].pkla with the following contents:



This makes it possible for everyone to restart or shutdown even though other users are logged in.

See also the manpages:

man pklocalauthority
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You can use command line to shut down pc in normal way.

sudo shutdown -h now

The shutdown command needs to be run as root and the general format is (from man shutdown):

shutdown [options] time

-h     Halt or power off after shutdown.

time   When to shutdown.
   The  time  argument  can  have  different formats.  First, it can be an
   absolute time in the format hh:mm, in which hh is the hour (1 or 2 dig‐
   its)  and mm is the minute of the hour (in two digits).  Second, it can
   be in the format +m, in which m is the number of minutes to wait.   The
   word now is an alias for +0.
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