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 ?

Solution

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.

Comments

[FedKad]

What is the output of df -t vboxsf command output on the guest? You can try to install the latest Guest Additions CD to the guest. Link: download.virtualbox.org/virtualbox/6.1.22/…

[Tomas.R]

df : no file systems processed

[FedKad]

What are the outputs of ps -ef | grep -i vbox and service --status-all | grep -i virtual on the guest?

[Tomas.R]

for ps : 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 for service, no output at all. UPDATED the question to see this clearer

[FedKad]

It seems that Guest Additions are not installed or working on the guest system. Please, search AskUbuntu topics about "installing guest additions" and try to fix any problem you encounter during the installation.

[Tomas.R]

Will do, thank you

[FedKad]

Let us continue this discussion in chat.

[spiilmusic]

On the macos this works too. But sometimes shared folder may breaks. Just try to recreate shared folder.

[Daniel]

Similar steps worked for me in host Ubuntu 18.04 and guest Ubuntu 21.04 but had to reboot after usermod since after logout still had permissioned denied to shared folder.