UPower

UPower is a D-Bus service for enumerating power devices on the system, monitoring their status, and implementing power management policies. It provides an abstraction layer for power management, allowing applications to query information about power sources such as batteries and AC adapters, and to react to changes in power state.

UPower aims to provide a consistent and reliable way for applications and desktop environments to manage power, regardless of the underlying hardware or operating system. It handles details like battery charging, discharging, and low power warnings. It replaces the older HAL (Hardware Abstraction Layer) power management APIs, offering a cleaner and more modern approach.

The core functionality of UPower includes:

• Device Enumeration: Discovering and listing available power devices.
• Status Monitoring: Tracking the state of power devices, such as battery charge levels, AC adapter connection status, and remaining time.
• Power Management Policy: Implementing system-wide policies for power saving, such as suspending the system after a period of inactivity.
• User Interaction: Providing information about power status to users, allowing them to control power settings.

UPower communicates with applications through D-Bus, a system-wide inter-process communication mechanism. This allows any application to query the UPower service for power-related information and to subscribe to signals that indicate changes in power state.

The UPower daemon, upowerd, runs as a system service. Configuration files, typically located in /etc/upower, control the behavior of the daemon and the implemented power management policies.

UPower is a crucial component of many Linux desktop environments, including GNOME and XFCE, and is widely used to provide a consistent and user-friendly power management experience.