sudo apt-add-repository ppa:fingerprint/fingerprint-gui && sudo apt-get update sudo apt-get install libbsapi policykit-1-fingerprint-gui fingerprint-gui
*It ought to be noted that the related PolicyKit package for the fingerprint stack will remove the default one (“policykit-gnome” , etc. depending on your environment) thus if you do decide to remove the fingerprint PPA, you must reinstall this package manually, or risk a broken system.
In order for the new defaults to take effect you’ll need to run the GUI and enroll a few fingers, then restart the session by logging out and back in.
Now you can have fun unlocking your screen, logging out and in, sudo-ing and running things with root privileges, using your fingerprints (or toeprints, should you choose to register one) –of course you can still use your password.
More info regarding this can be found on the Launchpad project page (such as a list of supported hardware, etc.)