postinst is in infon-server 0~r198-8.
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
# Automatically added by dh_metainit
# We assume that any previous installed /etc/init.d/infon-server
# and /etc/default/infon-server files that are conffiles are not wanted any more.
# Code taken from http://wiki.debian.org/DpkgConffileHandling
rm_conffile() {
    PKGNAME="$1"
    CONFFILE="$2"
    old_md5sum=`dpkg-query -W -f='${Conffiles}' $PKGNAME | awk '$3 == "obsolete" && $1=="'"$CONFFILE"'" {print $2}'`
    if [ -n "$old_md5sum" -a -e "$CONFFILE" ]; then
        md5sum="`md5sum \"$CONFFILE\" | sed -e \"s/ .*//\"`"
        if [ "$md5sum" != "$old_md5sum" ]; then
            echo "Obsolete conffile $CONFFILE has been modified by you."
            echo "Saving as $CONFFILE.dpkg-bak ..."
            mv -f "$CONFFILE" "$CONFFILE".dpkg-bak
        else
            echo "Removing obsolete conffile $CONFFILE ..."
            rm -f "$CONFFILE"
        fi
    fi
}
rm_conffile infon-server "/etc/default/infon-server"
rm_conffile infon-server "/etc/init.d/infon-server"
update-metainit  >/dev/null || exit $?
if [ -x "/etc/init.d/infon-server" ]; then
	if [ -x "`which invoke-rc.d 2>/dev/null`" ]; then
		invoke-rc.d infon-server start || exit $?
	else
		/etc/init.d/infon-server start || exit $?
	fi
fi
# End automatically added section
 |