postinst is in libselinux1 2.1.0-4.1ubuntu1.
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 17 18 19 | #!/bin/sh
set -e
if [ "$1" = "configure" ]; then
	# Upstart cannot be restarted without losing all of its state, so
	# umountroot will run 'telinit u' on reboot if this file exists
	# (NOTE: Borrowed from libc6.postinst)
	touch /var/run/init.upgraded
fi
# Automatically added by dh_makeshlibs
if [ "$1" = "configure" ]; then
	ldconfig
fi
# End automatically added section
exit 0
 |