VirtualBox Tips

Error: kernel headers not found
sudo apt-get install build-essential linux-headers-`uname -r` dkms
-----------------------------------
Shrink disk space Linux Guest
dd if=/dev/zero of=/tmp/zerofile; rm /tmp/zerofile
VBoxManage.exe modifyhd "Path\Debian.vdi" --compact

Shrink disk space Windows Guest
Clean disk
Defragment disk
http://technet.microsoft.com/en-us/sysinternals/bb897443.aspx
sdelete.exe C: -z
VBoxManage.exe modifyhd "Path\Debian.vdi" --compact
-----------------------------------
Change UUID
VBoxManage.exe internalcommands sethduuid "Path\Debian.vdi"
-----------------------------------
Manual mount and install Guest Additions

sudo mount /dev/cdrom /media/cdrom
cd /media/cdrom
sudo ./VBoxLinuxAdditions.run
reboot