root@OpenWrt:~/cake-autorate# cat test.sh
#!/bin/bash

kill_all()
{
        trap - INT TERM EXIT
        echo "Killing background with pid=$background_pid"
        kill $background_pid
        wait $background_pid
}

kill_background()
{
        trap - TERM EXIT
        echo "killing pinger with pid=$ping_pid"
        kill $ping_pid
        echo "killed pinger"
        exit
}

background()
{
        trap '' INT
        trap kill_background TERM EXIT

        ping 1.1.1.1&
        ping_pid=$!

        echo "Started ping with pid=$ping_pid"

        sleep inf

        echo "Background exited."
}

set -x

trap kill_all INT TERM EXIT

background&
background_pid=$!
echo "Started test.sh with background_pid=$background_pid"

sleep inf

echo "script termination"