Setting up Debian based Linux PC with Fingerprint Authentication

Here’s the complete step-by-step guide including cosmic-greeter setup for fingerprint login on Pop!_OS

Fingerprint Setup on Pop!_OS (Lenovo ThinkPad with COSMIC)

1. Install Required Packages

sudo apt update && sudo apt install fprintd libpam-fprintd

2. Reinstall cosmic-greeter (if needed). Ensure the login manager is working: 

sudo apt install --reinstall cosmic-greeter

3. Enable Fingerprint in PAM

sudo pam-auth-update

4. Use arrow keys to select "Fingerprint authentication". Press Space, then Tab → Enter
5. Enroll Your Fingerprint

fprintd-enroll

6. Swipe your finger until you see enroll-completed. You can specify a finger

fprintd-enroll -f right-index-finger

7. Reboot

sudo reboot

After reboot

1. Go to Settings > Users — you should see "Fingerprint Login" enabled
2. Use Fingerprint
3. At login: Swipe instead of typing password
4. For sudo: Run sudo ls and use your finger

Troubleshooting

1. No fingerprint option?
   sudo pam-auth-update --enable fprintd

BIOS conflict (ThinkPad):

Enter BIOS → Security → Fingerprint → Disable "Predesktop Authentication"