postinst is in ftpd 0.17-34.
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 | #!/bin/sh
# $Id: postinst,v 1.7 2003/06/21 02:31:44 herbert Exp $
set -e
if grep -q '[[:blank:]]/usr/sbin/in\.ftpd.*-z' /etc/inetd.conf 2>/dev/null; then
	update-inetd --pattern '/usr/sbin/in\.ftpd' --remove ".*ftp"
fi
if grep -q '[[:blank:]]/usr/sbin/in\.ftpd\>' /etc/inetd.conf 2>/dev/null; then
	if ! grep -q '^ftp\>' /etc/inetd.conf; then
		update-inetd --pattern '/usr/sbin/in\.ftpd' --multi --enable ftp
	fi
else
	FTPENTRY="ftp		stream	tcp	nowait	root	/usr/sbin/tcpd	/usr/sbin/in.ftpd"
	if grep -q '^ftp\>' /etc/inetd.conf 2>/dev/null; then
		update-inetd --group STANDARD --add "## $FTPENTRY"
	else
		update-inetd --group STANDARD --add "$FTPENTRY"
	fi
fi
if [ ! -f /etc/inetd.conf -a -d /etc/xinetd.d -a -x /usr/sbin/xinetd ]; then
	cat <<-TEXT
		------------------------------------------------
		There is an example configuration for using ftpd
		under the control of xinetd. It is delivered as
		    /usr/share/doc/fptd/examples/ftpd.xinetd
		------------------------------------------------
	TEXT
fi
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