Accessing shared folder on Virtualbox 6.1 - Windows 10 host - Ubuntu 20.04 SERVER guest

Question

I believe I did everything what was described on how to access a folder on my host - Windows 10 - from my guest - ubuntu 20.04. However I get no results.

Guest additions are installed on my VM :

The settings for shared folder :

Installed the latest Guest Additions CD

However, when I cd into my folder and list files there's nothing there. And I do keep a file there on my host, so it should be seen:

tomas@ubuntu20:~/share$ ls -l
total 0
tomas@ubuntu20:~/share$ df -t vboxsf
df : no file systems processed 
tomas@ubuntu20:~/share$ usermod -aG vboxsf tomas
usermod : group 'vboxsf' does not exist
tomas@ubuntu20:~/share$ chmod 755 .
tomas@ubuntu20:~/share$ ps -ef | grep -i vbox
root         385       2  0 10:19 ?        00:00:00 [iprt-VBoxWQueue]
tomas       1112    1098  0 10:24 pts/0    00:00:00 grep --color=auto -i vbox
tomas@ubuntu20:~/share$ service --status-all | grep -i virtual # no output
tomas@ubuntu20:~/share$ sudo mount -t vboxsf -o uid=1000,gid=1000 ubuntush /home/tomas/share
mount: /home/tomas/share: wrong fs type, bad option, bad superblock on ubuntush, missing codepage or helper program, or other error.

From Windows 10(host) Command Prompt:

C:\Users\as_to>VBoxManage sharedfolder add "ubuntu20" --name "ubuntush" --hostpath "C:\Users\as_to\Desktop\ubuntush"
VBoxManage.exe: error: Shared folder named 'ubuntush' already exists
VBoxManage.exe: error: Details: code VBOX_E_OBJECT_IN_USE (0x80bb000c), component SessionMachine, interface IMachine, callee IUnknown
VBoxManage.exe: error: Context: "CreateSharedFolder(Bstr(pszName).raw(), Bstr(szAbsHostPath).raw(), fWritable, fAutoMount, Bstr(pszAutoMountPoint).raw())" at line 1194 of file VBoxManageMisc.cpp

Does anybody know what is missing ?

Answer 1

With a help of great @FedonKadifeli I was able to solve the issue.

First and foremost - the guest OS is Ubuntu 20.04 LTS Server.

From a running guest OS window install Guest Additions. Go to : Devices - > Insert Guest Additions CD Image

Then to the guest OS command line :

sudo apt update
sudo apt upgrade

sudo mount /dev/sr0 /cdrom
mount: /cdrom: WARNING: device write-protected, mounted read-only. # This is OK

cd /cdrom 
sudo bash ./VBoxLinuxAdditions.run

The output of the last command should be something like that :

However, the last 3 lines of the output I got was saying this :

"This system is currently not set up to build kernel modules.
Please install the gcc make perl packages from your distribution.
VirtualBox Guest Additions: Running kernel modules will not be replaced until
the system is restarted"

So, first I had to install additional packages. And anything extra that may be needed:

sudo apt install gcc 
sudo apt install make
sudo apt install perl

Restart the guest :

reboot

Then from a Guest OS window go to :

Devices - Shared Folders - Shared Folders Settings - Add new Shared Folder :

Folder Path : C:\Users\as_to\Desktop\foo
Folder Name : foo

Mount point : /home/tomas/bar - This will create a directory after you close this window

Auto-mount (check)

Make Permanent (check)

Press OK to close the window.

Next, if you try to cd into bar you will get permission denied :

cd bar/
-bash: cd: bar/: Permission denied

Add user to the group "vboxsf" and logout/login again for the changes to be applied:

sudo usermod -aG vboxsf tomas
logout

And that's it. All should work now. Thank you again @FedonKadifeli, awesome guy.

Answer 2

Thanks for your post. I have the same versions as you: ubuntu 20.04, windows 10 (Host), virtualbox v6.1, but after all the above steps I still have an empty shared directory in ubuntu.

Looking at the mount after reboot I have this entry which doesn't look right:

$mount | grep shared
 /home/damo/shared on /home/damo/shared type vboxsf (rw,....)

Seems to be trying to mount the folder to itself instead of from windows...? The VM Shared folder settings are

Folder path: C:\Users\damo\VirtualBox VMs\shared
Mount point: /home/damo/shared

With auto mount and make permanent checked. Do I need to do something on the host side to enable sharing of a folder?

Answer 3

The instructions that worked for me came from: Unable to mount the CD/DVD image on the machine Sandbox and How to Install & Use VirtualBox Guest Additions on Ubuntu:

Install some packages in order to be able to build the kernel:

sudo apt install build-essential dkms linux-headers-generic

Install the VirtualBoxGuestAdditions from Ubuntu repository:

sudo apt install virtualbox-guest-additions-iso
sudo mkdir /media/GuestAdditionsISO
sudo mount -o loop /usr/share/virtualbox/VBoxGuestAdditions.iso /media/GuestAdditionsISO

Install the Guest Additions:

cd /media/GuestAdditionsISO
sudo ./VBoxLinuxAdditions.run

Reboot