UPower (previously DeviceKit-power) is a piece of middleware (an abstraction layer) for power management on Linux systems.

It consists of a daemon (upowerd), an application programming interface and a set of command line tools.

[3] PolicyKit restricts access to the UPower functionality for initiating hibernate mode or shutting down the operating system (freedesktop.upower.policy).

[4] The command-line client program upower can be used to query and monitor information about the power supply devices in the system.

As free software it is published with its source code under the terms of version 2 or later of the GNU General Public License (GPL).