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
```bash
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

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

Swipe your finger until you see enroll-completed.
You can specify a finger:
fprintd-enroll -f right-index-finger

5. Reboot
sudo reboot

After reboot:

Go to Settings > Users — you should see "Fingerprint Login" enabled.
6. Use Fingerprint
At login: Swipe instead of typing password. 
For sudo: Run sudo ls and use your finger.
Troubleshooting
No fingerprint option?
sudo pam-auth-update --enable fprintd

BIOS conflict (ThinkPad):

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