Ubuntu 24.04 - Enable / Disable Fingerprint Reader with Laptop Lid

README.md

Use the files here and the steps below to configure a laptop to enable and disable fingerprint auth support in PAM when the lid is opened or closed.

NOTE: Currently not working is setting the correct state when the machine first boots. It is just whatever is last.

Setup Requirements

• Install acpid
• Enable acpid

$ sudo apt install --assume-yes acpid
$ sudo systemctl enable --now acpid

Configure acpid

• Download the config file and bash script and install them into /etc/acpid

$ sudo install -D --owner=root --group=root --mode=0644 laptop-lid /etc/acpid/events/laptop-lid
$ sudo install -D --owner=root --group=root --mode=0744 laptop-lid.sh /etc/acpid/laptop-lid.sh
$ sudo systemctl restart acpid

Test

• Open lid and in a new terminal attempt to use sudo:

~ $ sudo bash
Place your finger on the fingerprint reader

• Close lid and in a new terminal attempt to use sudo:

~ $ sudo bash
[sudo] password for user: 

laptop-lid

event=button/lid.*
action=/etc/acpi/laptop-lid.sh "%e"

laptop-lid.sh

#!/bin/bash

# Function to get the lid state
get_lid_state() {
    for lid in /proc/acpi/button/lid/*; do
        if [ -d "$lid" ]; then
            state=$(cat "$lid/state" | awk '{print $2}')
            echo "$state"
        fi
    done
}

# Check all lid states
LID_STATES=$(get_lid_state)

if echo "$LID_STATES" | grep -q "closed"; then
    # Disable fprintd profile if any lid is closed
    echo "Disabling fprintd with pam-auth-update because at least one lid is closed."
    pam-auth-update --disable fprintd
    logger "fprintd disabled because at least one lid is closed"
elif echo "$LID_STATES" | grep -q "open"; then
    # Enable fprintd profile if all lids are open
    echo "Enabling fprintd with pam-auth-update because all lids are open."
    pam-auth-update --enable fprintd
    logger "fprintd enabled because all lids are open"
fi