preinst is in debian-reference-en 2.58.
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 | #! /bin/sh
# postinst script for debian-reference-*
#
# see: dh_installdeb(1)
set -e
case "$1" in
    install|upgrade)
	# remove old index.html (2.50/wheezy)
	if [ -d /usr/share/doc/debian-reference-common/html -a \
	     -f /usr/share/doc/debian-reference-common/html/index.html ]; then
	  rm -r /usr/share/doc/debian-reference-common/html/index.html
	fi
	# remove old directory if empty (no --ignore-fail-on-non-empty)
	rmdir /usr/share/doc/debian-reference-common/html 2>/dev/null || true
    ;;
    *)
	: # do nothing
    ;;
esac
# dh_installdeb will replace this with shell code automatically
# generated by other debhelper scripts.
exit 0
 |