postinst is in emacsen-common 2.0.8.
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 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 | #!/bin/sh
set -e
# Convert installed-flavors to flavor/installed/*.
if test -e /var/lib/emacsen-common/installed-flavors
then
  for flavor in $(cat /var/lib/emacsen-common/installed-flavors)
  do
    touch "/var/lib/emacsen-common/state/flavor/installed/$flavor"
  done
  rm -f /var/lib/emacsen-common/installed-flavors
fi
# Put debhelper section before emacs-package-install to avoid emacs
# complaints about missing /usr/local/share/emacs/site-lisp.
# Automatically added by dh_usrlocal
if [ "$1" = configure ]; then
(
	while read line; do
		set -- $line
		dir="$1"; mode="$2"; user="$3"; group="$4"
		if [ ! -e "$dir" ]; then
			if mkdir "$dir" 2>/dev/null; then
				chown "$user":"$group" "$dir"
				chmod "$mode" "$dir"
			fi
		fi
	done
) << DATA
/usr/local/share 2775 root staff
/usr/local/share/emacs 2775 root staff
/usr/local/share/emacs/site-lisp 2775 root staff
DATA
fi
# End automatically added section
/usr/lib/emacsen-common/emacs-package-install --postinst emacsen-common
 |