Persistent serial port names for USB-serial on OpenWrt hotplugd

10-persistent-serial.sh

[ "${ACTION}" = "bind" -o "${ACTION}" = "unbind" ] || exit 0
[ "${SUBSYSTEM}" = "usb-serial" ] || exit 0
[ -n "${DEVICENAME}" -a -n "${DEVPATH}" ] || exit 1

if [ "${ACTION}" = "bind" ]; then
        subsystem="$(basename $(readlink /sys${DEVPATH}/../subsystem))"

        [ "$subsystem" = "usb" ] || exit 0

	replace_whitespace="s/^[ \t]*|[ \t]*$//g; s/[ \t]+/_/g"
        manufacturer="$(sed -E "${replace_whitespace}" /sys${DEVPATH}/../../manufacturer)"
	# If manufacturer is blank, use vendor ID.
	: ${manufacturer:=$(cat /sys${DEVPATH}/../../idVendor)}
        product="$(sed -E "${replace_whitespace}" /sys${DEVPATH}/../../product)"
	# If product is blank, use product ID.
	: ${product:=$(cat /sys${DEVPATH}/../../idProduct)}
        serial="$(sed -E "${replace_whitespace}" /sys${DEVPATH}/../../serial)"
        interface="$(cat /sys${DEVPATH}/../bInterfaceNumber)"
        port="$(cat /sys${DEVPATH}/port_number)"

	replace_chars="s/[^0-9A-Za-z#+.:=@-]/_/g"
        id_link=$(echo "${subsystem}-${manufacturer}_${product}${serial:+_${serial}}-if${interface}${port:+-port${port}}" | \
	    sed "${replace_chars}")
        path_link=$(echo "${DEVPATH}${port:+-${port}}" | \
	    sed "s%/devices/%%; s%/${DEVICENAME}%%g; ${replace_chars}")

        mkdir -p /dev/serial/by-id /dev/serial/by-path
        ln -sf "/dev/${DEVICENAME}" "/dev/serial/by-id/${id_link}"
        ln -sf "/dev/${DEVICENAME}" "/dev/serial/by-path/${path_link}"
elif [ "${ACTION}" = "unbind" ]; then
        for link in $(find /dev/serial -type l); do
                [ -L ${link} -a "$(readlink ${link})" = "/dev/$DEVICENAME" ] && rm ${link}
        done
fi

Thanks for pointing this out. I've made a change that I believe fixes the problem.