preinst is in aolserver4-daemon 4.5.1-18.
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 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 | #!/bin/sh -e
# preinst script for aolserver
#
# see: dh_installdeb(1)
# summary of how this script can be called:
#        * <new-preinst> `install'
#        * <new-preinst> `install' <old-version>
#        * <new-preinst> `upgrade' <old-version>
#        * <old-preinst> `abort-upgrade' <new-version>
# Source debconf library
#. /usr/share/debconf/confmodule
# check for presence of www-data:www-data user
add_group_if_missing() {
    if [ -x /usr/sbin/adduser ]; then
        if ! id -g www-data >/dev/null 2>&1; then
                addgroup --gid 33 --force-badname www-data
        fi
    fi
}
                                                                                                              
add_user_if_missing() {
    if [ -x /usr/sbin/adduser ]; then
        if ! id -u www-data > /dev/null 2>&1; then
            adduser --system --home /var/www --no-create-home \
                --uid 33 --gid 33 --disabled-password --force-badname \
                www-data
        fi
    fi
}
case "$1" in
    upgrade|install)
    	add_group_if_missing
    	add_user_if_missing
    ;;
    abort-upgrade)
    ;;
    *)
        echo "preinst called with unknown argument \`$1'" >&2
        exit 0
    ;;
esac
# dh_installdeb will replace this with shell code automatically
# generated by other debhelper scripts.
 |