postrm is in libpam-runtime 1.1.8-1ubuntu2.2.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | #!/bin/sh -e
if [ "$1" = "purge" ]; then
	rm -f /etc/pam.d/common-auth /etc/pam.d/common-account \
	      /etc/pam.d/common-session /etc/pam.d/common-password
	rm -f /var/lib/pam/auth /var/lib/pam/account /var/lib/pam/session \
	      /var/lib/pam/password /var/lib/pam/seen
	rmdir --ignore-fail-on-non-empty /var/lib/pam
fi
# Automatically added by dh_installdebconf
if [ "$1" = purge ] && [ -e /usr/share/debconf/confmodule ]; then
	. /usr/share/debconf/confmodule
	db_purge
fi
# End automatically added section
 |