Linux: Programatically shutdown or reboot computer from a user-level process

Question

How do I programatically trigger a system shutdown or reboot in Linux? Preferably without requiring elevated privileges.

On older releases (e.g. Ubuntu 10.04) I could ca

Answer 1

The shutdown command. However, that requires root privileges on most systems.

Shutdown now:

shutdown -h now

Restart now:

shutdown -r now

man shutdown for more info.

Answer 2

You can use ConsoleKit. Send a org.freedesktop.ConsoleKit.Manager.Stop DBus message to org.freedesktop.ConsoleKit. From the command line, that would be something like:

dbus-send \
    --system \
    --dest=org.freedesktop.ConsoleKit \
    --type=method_call \
    --print-reply \
    --reply-timeout=2000 \
    /org/freedesktop/ConsoleKit/Manager \
    org.freedesktop.ConsoleKit.Manager.Stop

If the current user is authorized to perform shutdown, then no root privileges are needed.

You can also take a look at the KShutdown utility. It contains source code for different shutdown methods, ranging from ConsoleKit to Gnome and KDE APIs.