Sharing folders between VirtualBox host and guest machines

This post is the 4th installment of the VirtualBox series. The focus is on how to share folders between the host and the guest OSes. Part 1 of the series shows how to install VirtualBox on a Debian host, and how to create a FreeBSD virtual machine. Part 2 outlines the post installation tasks, including installing the universal VirtualBox extension pack. Part 3 shows how the guest OS can access USB drives mounted on the host.
The method outlined in this blog post works for Linux and Windows guest OSes but not FreeBSD. You can set up NFS or Samba to share a folder between a Linux host and a FreeBSD guest.

Prerequisites

To share a folder using the following procedure, the OS-specific guest additions package must be pre-installed. Part 1 of this series includes instructions for installing the guest additions package for the FreeBSD guest OS.

Procedure

1. Declare the shared folder on host OS.
   Open the Oracle VM VirtualBox manager on your host machine, select the target guest OS, and click Settings. Note that your guest machine does NOT need to be powered off.
   
2. Select Shared Holders, and click the Plus button to add a shared folder. Note that you can have more than 1 shared folder.
   
3. Specify the path for the shared folder.
   Click the down arrow next to the Folder Path parameter, select Other, and navigate to the target shared folder.
   
4. Configure the shared folder.
   The Folder name field refers to the folder name on the guest OS, which defaults to the folder name you specified in the last step. You should note the folder name in order to identify the full folder pathname on the guest OS. For example, if the shared folder on the host machine is /home/peter/Music, the corresponding folder name defaults to /media/sf_Music on the Ubuntu guest OS, and \\vboxsvr\Music on the Windows guest OS.
   
   The Auto-mount checkbox should be enabled. Optionally, you can also mount the folder manually, but then you must modify access permissions in order to make the folder writable by non-root users.
   
   Unless the shared folder is for one-off use only, you should enable the Make Permanent checkbox.
5. Power recycle the guest machine.
6. Grant folder access permission to non-root users.
   This step only applies to Linux guest OS(not Windows). Login to the guest OS, and add regular users to the vboxsf group using the following command.
   
   sudo usermod -aG vboxsf <someuserID>

Related posts

• Part 1 of VirtualBox series - on installation.
• Part 2 - post-installation.
• Part 3 - mounting of USB drives.