fprintd

View documentation for listing enrolled fingerprints

$ tldr fprintd-list

$ tldr fprintd-enroll

$ tldr fprintd-verify

$ tldr fprintd-delete

fprintd [OPTION...]

-v, --verbose
    Enable verbose output, providing more detailed information during operation.

-f, --foreground
    Prevents the daemon from forking into the background, useful for debugging.

-d, --debug
    Enables debugging output, offering extensive diagnostic messages.

-h, --help
    Displays a help message with available command-line options.

--version
    Shows the version information of the fprintd daemon.

fprintd is the D-Bus system service that manages fingerprint readers and operations on Linux. It provides a standardized interface for applications and PAM modules (like pam_fprintd) to interact with various fingerprint hardware devices. This service handles tasks such as enrolling new fingerprints, verifying existing fingerprints, deleting enrolled prints, and managing a list of enrolled users.

By centralizing these operations, fprintd abstracts away the complexities of different fingerprint hardware, offering a unified API for biometric authentication. It typically runs in the background as a system service, listening for D-Bus requests from clients that need to perform fingerprint-related actions, enhancing system security and user convenience.

Hardware compatibility relies heavily on the underlying libfprint library, which might not support all fingerprint readers, particularly newer or proprietary models. While fprintd aims for secure biometric authentication, overall system security also depends on the integrity of the operating system and the hardware. Sensitive fingerprint data must be handled with care.

fprintd exposes a well-defined D-Bus interface, typically under the service name net.reactivated.fprint. This interface allows other processes, such as desktop environments, login managers (like GDM), and command-line tools, to communicate with the service and perform fingerprint-related operations.

Most user interaction with fprintd is indirect. Users rarely invoke fprintd directly from the command line. Instead, they interact with higher-level applications (e.g., graphical user interface settings panels) or PAM modules (e.g., during login or sudo prompts) that utilize fprintd's D-Bus API to manage and use fingerprints.

fprintd is a key component of the broader libfprint project, which was initiated to provide a free and open-source library for fingerprint reader support on Linux. Its development aimed to standardize fingerprint integration across various Linux distributions and desktop environments, moving away from fragmented, hardware-specific solutions. It has become a foundational element for biometric authentication in modern Linux systems since its inception.

libfprint(7), pam_fprintd(8), fprintd-enroll(1), fprintd-verify(1), fprintd-delete(1), systemd(1), dbus-daemon(1)