upowerd

upowerd [OPTIONS]

Note: upowerd is typically run as a system daemon, managed by an init system like systemd, and is not usually invoked directly by users from the command line.

--verbose
    Enables verbose debugging output. This directs additional diagnostic information to syslog or standard error, useful for troubleshooting issues with the daemon.

--replace
    Replaces any existing upowerd instance. This option is primarily used during development or debugging to run a new instance of the daemon without manually stopping the old one.

--help
    Displays a brief help message detailing available command-line options and exits.

--version
    Shows the version information of the upowerd daemon and exits.

upowerd is the daemon for the UPower system service, providing a comprehensive, high-level abstraction for power management on Linux systems. It acts as a central authority for power-related information, enumerating power devices (like batteries, AC adapters, UPS units), tracking their state (e.g., charge level, power source), and providing notifications when their status changes. Applications, including desktop environments and power management utilities, communicate with upowerd via its D-Bus API to retrieve power information, manage power profiles, and handle events such as low battery warnings or suspend/hibernate requests. It unifies power management across various hardware and software configurations, offering a standardized interface for power-aware applications. Its primary role is to abstract away the complexities of interacting directly with hardware and various kernel interfaces for power management.

Users should generally not attempt to run or manage upowerd directly from the command line. It is a fundamental system service that should be managed by the distribution's init system (e.g., systemd). Direct manipulation can lead to system instability or incorrect power management behavior. Interaction with upowerd's functionality is intended to be done programmatically via its D-Bus interface or through user-facing client utilities like upower(1) or desktop environment power managers.

upowerd exposes its functionality through a well-defined D-Bus interface. Applications and desktop components do not directly execute upowerd commands but instead communicate with the running daemon over D-Bus to query power device status, subscribe to power-related events (like battery level changes), and request power actions (such as suspend or hibernate). This service-oriented architecture ensures robust and secure interaction with power management capabilities, abstracting away the underlying hardware details.

upowerd's behavior can be configured through a configuration file, typically located at /etc/UPower/UPower.conf. This file allows administrators to customize various aspects of power management, such as thresholds for low battery warnings, polling intervals for power devices, and other daemon-specific settings. Changes to this file usually require restarting the upowerd service to take effect for the new configurations to be applied.

upowerd, as part of the UPower project, emerged as a modern, standardized solution for power management on Linux, particularly for desktop environments adhering to the freedesktop.org specifications. It aimed to provide a unified D-Bus API for power information, centralizing power management functionality that was previously handled by more disparate and less integrated mechanisms like acpid for ACPI events and pm-utils for power state transitions. Its development reflects the broader trend in Linux desktop environments towards D-Bus-centric services for system-wide functionalities, ensuring consistent and robust power management across different distributions and desktop environments.

upower(1), systemd(1), dbus-daemon(1), acpid(8), pm-utils(8)