After this, note that you may need to tweak the permissions of `/media/externalharddrive` so that `www-data` (or the user corresponding to the app) is able to read through the folder... Something like :
```shell
chgrp www-data /media/externalharddrive
chmod g+rx /media/externalharddrive
```
(but it depends on your exact setup... Please update this doc page if you figure