#!/usr/bin/sh

for f in /tmp/dhclient.*.pid; do
    [ -e "$f" ] || continue
    read -r PID < "$f"
    kill "$PID" > /dev/null 2>&1
done

sleep 0.1

for f in /tmp/dhclient.*.pid; do
    [ -e "$f" ] || continue
    read -r PID < "$f"
    kill -9 "$PID" > /dev/null 2>&1
done