Some distros don’t allow you to
shutdown -r now
from terminal without superuser password.
Shutdown/Reboot/Suspend/Hibernate with user priviliges in Linux is possible via D-Bus. You just need consolekit and upower packages installed.
Here are the commands:
| Operation | D-Bus command | 
|---|---|
| Suspend | dbus-send --print-reply --system --dest=org.freedesktop.UPower /org/freedesktop/UPower org.freedesktop.UPower.Suspend | 
| Hibernate | dbus-send --print-reply --system --dest=org.freedesktop.UPower /org/freedesktop/UPower org.freedesktop.UPower.Hibernate | 
| Reboot | dbus-send --system --print-reply --dest=org.freedesktop.ConsoleKit /org/freedesktop/ConsoleKit/Manager org.freedesktop.ConsoleKit.Manager.Restart | 
| Shutdown | dbus-send --system --print-reply --dest=org.freedesktop.ConsoleKit /org/freedesktop/ConsoleKit/Manager org.freedesktop.ConsoleKit.Manager.Stop | 
Just paste them in your beloved terminal emulator and press enter 