Script to automatically bind and unbind external USB drive on Synology NAS

bind-backup.sh

#!/bin/bash

SERIAL="00000000"

echo "Looking for device with serial $SERIAL..."
for d in /sys/bus/usb/devices/*-*; do
    if [[ -f "$d/serial" ]]; then
        serial=$(<"$d/serial")
        if [[ "$serial" = "$SERIAL" ]]; then
            device="$(basename $d)"
            break
        fi
    fi
done

if [[ -z "$device" ]]; then
    echo "Fail to find device with serial $SERIAL"
    exit 1
fi

echo "Binding device $device..."
echo "$device" > /sys/bus/usb/drivers/usb/bind || exit 1

echo -n "Waiting for filesystem to mount... "
exec 3< <(tail -f -n1 /var/log/kern.log)
while read line; do
    if [[ "$line" = *"[EXFAT] mounted successfully" ]]; then
        echo "Mounted!"
        break
    elif [[ "$line" = *"usb $device: "* && "$line" = *" error "* ]]; then
        echo "Error!"
        exit 1
    fi
done <&3

echo -n "Waiting for filesystem to unmount... "
while read line; do
    if [[ "$line" = *"[EXFAT] unmounted successfully" ]]; then
        echo "Unmounted!"
        break;
    fi
done <&3

echo "Unbinding device $device..."
echo "$device" > /sys/bus/usb/drivers/usb/unbind

Also, un-mounting (=ejecting) the device via the GUI just adds one single line to kern.log:

so I suppose the next part of the script also won't recognize unmounting the hdd

Also, don't you need to put
exec 3< <(tail -f -n1 /var/log/kern.log)
in front of
echo -n "Waiting for filesystem to unmount... " while read line; do if [[ "$line" = *"[EXFAT] unmounted successfully" ]]; then echo "Unmounted!" break; fi done <&3
, as well, in order to read the kern.log?

Thanks!

The script here relies on the log from kernel, and it apparently supports only exFAT filesystem. I have no idea about your system and external disk so I can't really provide any advice. There is probably a better way to detect mounting and unmounting... but as it's working for me, I'm not very motivated to investigate further.

Also, don't you need to put
exec 3< <(tail -f -n1 /var/log/kern.log)
in front of

no, actually that would probably be wrong, IIRC. The previous one would be reused by the second loop.

@e92335i Sorry for the late reply. I didn't notice that there was comment on this script.

The serial number is not the serial number of the product, but something that the system recognize. You would need to figure out this string through /sys/bus/usb/devices/*/serial.

I keep getting a Permission Denied command when I replace the * with either usb2 or 2-2. Am I plugging in this command correctly? I can't get this binding script to function because I can't figure out the right serial ID. I'm assuming the serial string listed under lsusb is not correct either. I'm running my external with exFAT. Any help would be appreciated, thank you.

@matthewboteilho You would probably have to explore your device's information first by looking around in /sys/bus/usb/devices and try to figure out which one is the device you are after and then read from its serial.