Ubuntu – How to automatically mount a folder and change ownership from root in virtualbox

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It is my first time using virtualbox and ubuntu (14.04), I am on a host Windows 7 OS.

I am trying to mount a shared folder that has files I need to access both in the virtualbox and on the windows OS. I have successfully mounted them using the vboxsf from the Guest Additions installed.

To mount I used the command sudo mount -t vboxsf <dir name in vbox> <directory in linux for example I used sudo mount -t vboxsf Test /home/user/Test

I found several ways of mounting the directories automatically upon startup using for example the /etc/rc.local method (here) where you modify said file appending the command to it (without sudo). Or by using the fstab method (here). I prefer the rc.local method personally.

Once mounted it has permissions dr-xr-xr-x however once mounted the directory is of root ownership and chown user /home/user/Test has no effect. This means I cannot make or change files in it as a normal user.

In the VirtualBox the directory to be shared is not set as read-only.

Is there a way to automatically mount the shared folder and assign ownership to my non root user?

Best Answer

If you have the guest additions installed, use the VirtualBox menu:

Devices > Shared Folders...

Add the path, name and enable "Auto-mount" and "Make permanent" options.

Finally add your user to the group with:

sudo usermod -G vboxsf -a myusername

Logout and back again or reboot the machine to complete the process (thanks @Fo).

Groups are stored in /etc/group, according to the usermod man page.

Related Solutions

VirtualBox – Protocol Error Mounting VirtualBox Shared Folders in an Ubuntu Guest

In order to use shared folder functionality few prerequisites need to be met:

Make sure that Guest Additions are properly installed on the guest OS.
Users in a guest Ubuntu must be in the group vboxsf to be able to access shares.
Define a directory on the host that will be used in the virtual machine using the settings dialogue of Virtual Box.

Depending on host or guest OS the following may also be needed:

Do not share personal folders like /home/username or My Documents
Avoid special characters or empty spaces in the path to the shared folder, especially if the host or VM is a Windows machine
Use different names for share and mountpoint
Create a mountpoint on the guest OS (best in your HOME directory).

Testing shared folders functionality can be done by creating a shared directory on the host (e.g. C:\myshare), define this as a shared folder for your guest system in Virtual Box settings (e.g. share), create a mount point in your guest os (e.g. mkdir /home/username/host) and mount this in the guest OS with the command:

sudo mount -t vboxsf -o uid=1000,gid=1000 share /home/username/host

where the option -o makes sure that you will have access to the mount (that will otherwise be owned by root).

For further information on shared folders see also the Virtual Box User Manual.

Files or directories can also be shared over the network by using Samba on the host and the guest.

VirtualBox – How to Mount a VirtualBox Shared Folder at Startup

To always mount a Virtual Box "shared folder" on booting an Ubuntu guest we have two options. It is up to personal preference which option works best in our setting.

1. Mount with fstab

To mount a shared folder using the vboxsf filesystem provided with Guest Additions we first need to make sure prerequisites are met. Then we may put the following line in our etc/fstab file:

<name_of_share>   /path/to/mountpoint   vboxsf   <options>  0   0

Replace name_of_share and /path/to/mountpoint with your individual setup (the directory for the mountpoint has to be created first). See the manpage for mount <options>. One possibility is to mount with defaults, or to give specific mount options (e.g. rw, suid, exec, auto, users).

On some systems the vboxsf kernel module is not yet loaded at the time fstab is read on boot. It may then help to append the vboxsf kernel module to /etc/modules.

Some systems may need option comment=systemd.automount in their fstab entry (source).

2. Mount with Virtual Box "automatic mounting":

In recent releases of Virtual Box we can also automatically mount shared folders on creation:

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After a reboot of the guest this shared folder will be mounted to the guest directory /media/<username>/sf_<name_of_share> accessible to all users who had been made member of the group vboxsf.