Found now the solution:
I am on Raspian Buster and this automounts USB-Sticks as soon as they are plugged in. But only for user “pi”.
Any “chmod” commands have no influence to authorisations of the USB Stick. Authorisations have to be done during mounting of the stick.
What I did was to add the details of the USB Stick to the end of /etc/fstab. I added one line:
UUID=XXXX-XXXX /media/usb vfat auto,nofail,umask=000,noatime,users,rw,uid=pi,gid=pi 0 0
Replace the XXXX-XXXX with the UUID of your drive. You can find it out with this command:
ls -l /dev/disk/by-uuid/
Check the line that refers to “/sda1”
Important is the option “umask=000” that defines that all users have access to the USB stick.
Now reboot and find the content of your stick at /media/usb.
Define this location in /etc/mopidy/mopidy.conf:
[local]
media_dir = /media/usb
Restart mopidy, do a local scan and you will find Iris and Mopidy Mobile working fine !
Note: Works only if your stick is formated as FAT32.
Kind Regards.
Martin Klein