Thanks for sharing. While tweaking the formatting, I accidentally introduced a t...

Thanks for sharing. While tweaking the formatting, I accidentally introduced a typo which led to me spending a few minutes hunting for a fix for "sudo: unable to initialize PAM: No such process" without having to reboot :(

Anyway, here's the version of your one-liner I used to preserve the spacing used in the rest of the file:

   sudo perl -pi -e 's/(pam_smartcard.so)/$1\nauth       sufficient     pam_tid.so/' /etc/pam.d/sudo