Ele usa uma mensagem DBus.
dbus-send --system --print-reply --dest=org.freedesktop.Hal \
/org/freedesktop/Hal/devices/computer \
org.freedesktop.Hal.Device.SystemPowerManagement.Shutdown
Encontrei este aqui .
Reinicializar:
dbus-send --system --print-reply --dest=org.freedesktop.Hal \
/org/freedesktop/Hal/devices/computer \
org.freedesktop.Hal.Device.SystemPowerManagement.Reboot
Suspender:
dbus-send --system --print-reply --dest=org.freedesktop.Hal \
/org/freedesktop/Hal/devices/computer \
org.freedesktop.Hal.Device.SystemPowerManagement.Suspend int32:1
Hibernar:
dbus-send --system --print-reply --dest=org.freedesktop.Hal \
/org/freedesktop/Hal/devices/computer \
org.freedesktop.Hal.Device.SystemPowerManagement.Hibernate