fprind

Display the man page for fprintd

$ man fprintd

While `fprind` is not a direct command, it represents the `fprintd` daemon and its associated client utilities. Common commands used to interact with the fingerprint system are:
`fprintd-enroll [OPTIONS] DEVICE_ID
`fprintd-verify [OPTIONS] DEVICE_ID
`fprintd-list
`fprintd-delete DEVICE_ID
These commands interact with the running `fprintd` daemon to perform specific fingerprint-related tasks, where `DEVICE_ID` is the identifier of the fingerprint device.

-h, --help
    Displays a help message and exits for the specific `fprintd` client command (e.g., `fprintd-enroll`).

-f, --finger
    Specifies which finger to enroll or verify (e.g., `left-thumb`, `right-index-finger`). For `fprintd-enroll`, if not specified, it will prompt interactively. For `fprintd-verify`, it limits the verification to a specific finger.

-u, --user
    Specifies the user for whom to enroll or verify the fingerprint. Defaults to the current user.

-p, --prompt
    Forces interactive prompting for the finger to use during enrollment with `fprintd-enroll`.

-r, --retrieve
    For `fprintd-enroll`, allows re-enrolling an existing fingerprint for a user without prior deletion (requires confirmation). Not applicable to `fprintd-verify`.

The term `fprind` often refers to the `fprintd` system daemon, which provides a standardized D-Bus interface for interacting with fingerprint readers on Linux systems. It is not a direct command-line utility itself, but rather a background service. Applications, and more commonly, user-facing client commands like `fprintd-enroll` and `fprintd-verify`, communicate with `fprintd` to manage fingerprint data, including enrolling new fingerprints and verifying existing ones. `fprintd` aims to abstract away the complexities of different fingerprint reader hardware, offering a unified way for the desktop environment, login managers, and other applications to use fingerprint authentication. This enables features such as logging into your desktop environment, authenticating `sudo` commands, or unlocking screens using your fingerprint.

The term `fprind` is not a standard Linux command. It is commonly a misspelling or an informal reference to the `fprintd` daemon and its associated client utilities like `fprintd-enroll` and `fprintd-verify`. Direct execution of `fprind` or `fprintd` (without specific arguments or as a service command) from the terminal will typically result in a "command not found" error or usage information for the daemon itself. Fingerprint functionality relies on `fprintd` being installed, running, and having compatible hardware.

`fprintd` integrates with the Pluggable Authentication Modules (PAM) framework through the `pam_fprintd` module. This allows system-wide authentication tasks, such as login (graphical or console), `sudo` command execution, or screen unlocking, to leverage fingerprint authentication. To enable this, `pam_fprintd` needs to be configured in the relevant PAM service files (e.g., `/etc/pam.d/sudo`, `/etc/pam.d/login`, `/etc/pam.d/gdm-password`). After configuration, users can authenticate using their enrolled fingerprints in addition to or instead of their traditional password.

The functionality of `fprintd` is dependent on the underlying `libfprint` library's support for specific fingerprint reader hardware. While `libfprint` supports a wide range of devices, not all fingerprint readers are supported out-of-the-box, particularly newer or proprietary models. Users should check `libfprint` documentation or community resources for compatibility with their specific device.

The `fprintd` project emerged from the `libfprint` library, which was created to provide a generic, open-source library for accessing fingerprint readers. `fprintd` was developed to provide a standardized D-Bus interface on top of `libfprint`, making fingerprint authentication easily integratable into desktop environments and other applications, independent of the specific hardware or application framework. Its development aimed to bring robust and user-friendly fingerprint authentication to the Linux desktop, improving upon earlier, more fragmented solutions. It became a widely adopted solution for fingerprint support in many Linux distributions.

fprintd(8), pam_fprintd(8), dbus(1)