Shutdown the local machine now:

shutdown -s

Showing a dialog box with a timer (in seconds):

shutdown -s -t 60

With a timer and a message:

shutdown -s -t 120 -c "Please save your work immediately because the server is being rebooted!"

Shutdown another computer in your domain:

shutdown -s -m \\computername -t 10

Cancel a shutdown:

shutdown -a

Download and extract the PsTools package from SysInternals (now Microsoft). We extract the zip archive into C:\Support\PsTools\ as a convention.

Use the 'at' command to schedule a one-off reboot:

at 2:00am c:\support\pstools\psshutdown.exe -r -f -c -t 10

or shutdown:

at 2:00am c:\support\pstools\psshutdown.exe -s -f -c -t 10

Where:

-s: Shutdown windows server
-r: Reboot windows server
-f: Forces all running application to exit
-c: Allow the shutdown to be canceled user
-t: Specifies the countdown in seconds until the shutdown

http://www.itbox4vn.com/2011/05/how-to-schedule-windows-server-20032008.html