- Install packages if they aren't already installed.
sudo apt install libpam-pwdfile whois- Backup the Original PAM Configuration File
sudo cp /etc/pam.d/gdm-password /etc/pam.d/gdm-password_ORIGINAL- Create the Custom PIN File
echo "$(whoami):$(mkpasswd -5)" | sudo tee /etc/custompinfile
sudo chmod 400 /etc/custompinfile- Edit the PAM Configuration File to Enable the PIN file
Use your editor of choice with superuser privileges to edit the /ect/pam.d/gdm-password file to add auth sufficient pam_pwdfile.so pwdfile=/etc/custompinfile to the top of the file, similar to the following:
sudo vim /etc/pam.d/gdm-passwordThe top of your configuration file should look like the following:
#%PAM-1.0
auth sufficient pam_pwdfile.so pwdfile=/etc/custompinfile

Thank you! It's working as expected immediately after setup. Shared here: https://www.benjaminoakes.com/2025/06/04/Setup-Ubuntu-for-PIN-Login-Instead-of-Long-Password/