I have a Linux installation inside a VirtualBox VM (VDI file) that I would like to transfer to a physical hard disk. What would be the best way to do this? Could I mount the physical hard drive as a shared folder and use the dd command (booting the VM from a LiveCD) to transfer it? Note, both the VDI and the physical drive are the same size. Any ideas/advice would be appreciated.

The problem with the mounting is that you normally use dd on a raw-device,
not on a file-system. For the transfer you could use dd & netcat, or tar &
netcat ....

How would you use netcat to help do this? Also, what about allowing raw disk access to the destination volume? Potentially dangerous-I know but would it work better? Are there any other ways anyone would recommend?

That (raw device) is exactly what you'd be doing with netcat and dd ...

E.g.
http://www.rajeevnet.com/hacks_hints...s_cloning.html
for a how-to (there's heaps - search google for "netcat dd clone").

Cheers,
Tink

Note this method will only work if you have a static .vdi VirtualBox drive image; if you are using a dynamic .vdi drive, I'm still in the process of figuring out how to mount them. But if you happen to have a static .vdi drive, I think probably the easiest way to transfer your VirtualBox OS to a partition would be to mount it, and then copy its entire file system to its new partition with "cp -ax" to preserve all the proper permissions/ownerships of all files. Most VirtualBox .vdi files just have 3 sectors of VirtualBox header info at the beginning, and then the rest is the HDD image. So to mount a static .vdi file, you can usually do:
That will also return the loop device that the .vdi file gets associated with, for example "/dev/loop0". And then to see the partitions in that image:
Using the above command, find the sector offset of the partition you want to mount, say for example the starting sector is 63, then do:
And that will mount your VirtualBox OS partition on /mnt. After that, it's just a matter of copying the file system to its new partition:
And lastly, if you do:
It will show you the UUID of your mounted VirtualBox partition, and you can transfer that UUID to the new partition with:
You will probably have to modify /boot/grub/menu.lst and possibly /etc/fstab for the OS on the new partition, but that should be about all it takes. Let me know if you decide to give this method a try and how it goes.