Ubuntu in VirtualBox does not have permission to access the shared folder/media/sf_bak

has been done to automatically share folders, but now found unable to access, non-root users, using the "Ls/media/sf_bak" prompt does not have permission, of course, if you switch to root, it is possible.

"Resolution Process"
1, add the ordinary user name into the vboxsf. Because your user name is not vboxsf this user group.
Add Boarmy to vboxsf this user group below.
boarmy@boarmy-ubuntu:~$ sudo adduser boarmy vboxsf
Adding user "Boarmy" to "vboxsf" group ...
Adding user "Boarmy" to the "vboxsf" group
Complete.
crifan@crifan-ubuntu:~$
2. Go back to the command line:
boarmy@boarmy-ubuntu:~$ Ls/media/sf_bak
However, you still cannot access the shared folder.

3. Restart Ubuntu to see if it is useful.

The result is that you can actually use the shared folder: