Here's how I got it working,
Installed Rsync via the LibreElec Repository from with Kodi
Then via WinSCP I did this....
Within this folder I created two files
/storage/.config/udev.rules.d
USBCopy.rules
The name/label of the USB drive in this is the very inventive USB_Hard_Drive
ACTION=="add", KERNEL=="sd[a-z]1", ENV{ID_FS_LABEL}=="USB_Hard_Drive", RUN+="/storage/.config/udev.rules.d/USBCopy.sh"
USBCopy.sh
Had the code wait for 20 seconds while it was mounted, it then displayed a notification to say it was copying the TVShows folder, when done moved on to the Movies folder
The blue writing is the local folder, the green is the folder on the USB Drive I want the files to go to
#!/bin/sh
sleep 20
kodi-send -a "Notification(Copying to USB, TV Shows)"
/storage/.kodi/addons/network.backup.rsync/bin/rsync -avr /var/media/USB_T_MAIN/TVShows /var/media/"USB Hard Drive"
kodi-send -a "Notification(Copying to USB, Movies)"
/storage/.kodi/addons/network.backup.rsync/bin/rsync -avr /var/media/USB_T_MAIN/Movies /var/media/"USB Hard Drive"
kodi-send -a "Notification(All Copied to the USB, You can remove it!)"
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Finally had to make the USBCopy.sh file executable
/storage/.config/udev.rules.d/USBCopy.sh
I then rebooted the computer and when I plugged in the hard drive it began to work. If I have done anything wrong please let me know!