#!/bin/bash

find_config_files() {
	[ -z "$1" ] && return 0
	[ -r "$1" ] || return 1
	local CUR_CONF=$1
	local RESULT=$CUR_CONF
	for INCLUDED_FILE in $( sed -e "s/#.*//; s/.*\binclude[ \t]\+[\"']\([^\"]\+\)\".*/\1/; t; d;" $CUR_CONF ) ; do
		RESULT="$RESULT $( find_config_files $INCLUDED_FILE )"
	done
	echo $RESULT
}

grep -n . $( find_config_files /etc/dhcp/dhcpd.conf ) \
| sed -e 's/:\([0-9]\+\):/ line \1: /;'