+#!/bin/bash
+# I, Ian Kelling, follow the GNU license recommendations at
+# https://www.gnu.org/licenses/license-recommendations.en.html. They
+# recommend that small programs, < 300 lines, be licensed under the
+# Apache License 2.0. This file contains or is part of one or more small
+# programs. If a small program grows beyond 300 lines, I plan to change
+# to a recommended GPL license.
+
+# Copyright 2024 Ian Kelling
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+# http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+# usage: wrt-reip PATTERN
+# Removes pattern from dnsmasq leases file and restart dnsmasq.
+# PATTERN should generally be an ip or a mac.
+
+pattern=$1
+
+exit_code=0
+
+m() {
+ printf "%s\n" "$*";
+ "$@"
+}
+
+m /etc/init.d/dnsmasq stop
+
+tmp=/tmp/dhcp.leases.iank
+sed "/$pattern/d" /tmp/dhcp.leases >$tmp
+
+if (( $(wc -l /tmp/dhcp.leases | awk '{print $1}') - 1 == $(wc -l $tmp | awk '{print $1}') )); then
+ echo "info: found one less line after removing $pattern. installing new leases file"
+ cp /tmp/dhcp.leases /tmp/dhcp.leases.iank-backup
+ cat $tmp >/tmp/dhcp.leases
+ m rm -f $tmp
+else
+ exit_code=1
+ cat <<EOF
+error: unexpected line count in /tmp/dhcp.leases.iank"
+try diffing /tmp/dhcp.leases{,.iank}
+EOF
+fi
+
+m /etc/init.d/dnsmasq start
+
+m exit $exit_code