I believe I have done everything all the manuals have said to get this to work, and have been struggling with it for a few days now. Here are the details of the setup:
Host: Linux Mint 18.1 Serena, Ubuntu 5.4.0-6ubuntu1~16.04.4, 4.4.0-53-generic
Guest: Debian GNU/Linux 10 (buster), 4.19.0-8-amd64
Virtualbox version: 5.1.38_Ubuntu
Guest Editions version: 5.1.38
Guest Editions is installed in the guest, my user is part of the group vboxsf, in the gui of Virtualbox on the host, I selected a folder in the host home directory which I made called MintDebianSharedFolder and selected Auto-Mount, and gave the name to be seen by the guest MintDebianSharedFolder5. Now upon booting the guest (Debian 10):
cardamom@ruthenium:~$ sudo ls -la /media/
insgesamt 14
drwxr-xr-x 4 root root 4096 Mär 24 12:41 .
drwxr-xr-x 19 root root 4096 Mär 23 14:34 ..
lrwxrwxrwx 1 root root 6 Mär 23 13:19 cdrom -> cdrom0
dr-xr-xr-x 6 root root 2048 Mai 9 2018 cdrom0
drwxrwx--- 2 root vboxsf 4096 Mär 24 12:38 sf_MintDebianSharedFolder5
cardamom@ruthenium:~$ sudo ls -la /media/sf_MintDebianSharedFolder5/
insgesamt 8
drwxrwx--- 2 root vboxsf 4096 Mär 24 12:38 .
drwxr-xr-x 4 root root 4096 Mär 24 12:41 ..
There are in fact 2 files in the corresponding folder on the host - Why are they not showing up in the guest?
I created the second one just a moment ago on the host, but it is just not visible in the guest.
Here is the output of a few other commands on the Debian 10 guest which may help diagnose:
cardamom@ruthenium:~$ df
Dateisystem 1K-Blöcke Benutzt Verfügbar Verw% Eingehängt auf
udev 3354284 0 3354284 0% /dev
tmpfs 674824 9084 665740 2% /run
/dev/sda1 7578488 5697972 1475832 80% /
tmpfs 3374108 0 3374108 0% /dev/shm
tmpfs 5120 4 5116 1% /run/lock
tmpfs 3374108 0 3374108 0% /sys/fs/cgroup
tmpfs 674820 20 674800 1% /run/user/1000
/dev/sr0 58214 58214 0 100% /media/cdrom0
cardamom@ruthenium:~$ mount | grep sf
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
cardamom@ruthenium:~$ sudo VBoxControl guestproperty get /VirtualBox/GuestAdd/SharedFolders/MountDir
Oracle VM VirtualBox Guest Additions Command Line Management Interface Version 5.1.38
(C) 2008-2018 Oracle Corporation
All rights reserved.
No value set!
cardamom@ruthenium:~$ lsmod | grep vboxguest
vboxguest 299008 4
cardamom@ruthenium:~$ cd /opt/VBoxGuestAdditions-*/init
cardamom@ruthenium:/opt/VBoxGuestAdditions-5.1.38/init$ ls
vboxadd vboxadd-service vboxadd-x11
cardamom@ruthenium:/opt/VBoxGuestAdditions-5.1.38/init$ sudo ./vboxadd setup
vboxadd.sh: failed: Look at /var/log/vboxadd-install.log to find out what went wrong.
vboxadd.sh: Starting the VirtualBox Guest Additions.
vboxadd.sh: failed: modprobe vboxsf failed.
Any ideas much appreciated