small-package/luci-app-packet-capture/root/usr/libexec/packet_capture_stop

#!/bin/sh

pid=$(cat /var/run/packet_capture.pid)
if [ -n "$pid" ] && grep -sq packet_capture "/proc/$pid/cmdline"; then
    ppid=$(pgrep -P $pid)
    kill -TERM $ppid
fi

exit 0