I am running VirtualBox 4.1.12, downloaded from Oracle and anytime you upgrade the main application, you must reinstall the Extension pack to match as it will be blank at first after the upgrade or new install.
as root in a terminal. It will install the Extension Pack matching the version of VirtualBox you have installed. After updating virtualbox, just type it again. If you already have the correct version of the Extension Pack, nothing happens.
Example:
# **VBoxExtensionPack **
- Downloading http://download.virtualbox.org/virtualbox/4.1.12/Oracle_VM_VirtualBox_Extension_Pack-4.1.12-77245.vbox-extpack ...
asking libproxy about url 'http://download.virtualbox.org/virtualbox/4.1.12/Oracle_VM_VirtualBox_Extension_Pack-4.1.12-77245.vbox-extpack'
libproxy suggest to use 'direct://'
--2012-04-14 20:30:42-- http://download.virtualbox.org/virtualbox/4.1.12/Oracle_VM_VirtualBox_Extension_Pack-4.1.12-77245.vbox-extpack
Resolving download.virtualbox.org... 137.254.16.69
Connecting to download.virtualbox.org|137.254.16.69|:80... connected.
HTTP request sent, awaiting response... 302 Moved Temporarily
Location: http://dlc.sun.com.edgesuite.net/virtualbox/4.1.12/Oracle_VM_VirtualBox_Extension_Pack-4.1.12-77245.vbox-extpack [following]
asking libproxy about url 'http://dlc.sun.com.edgesuite.net/virtualbox/4.1.12/Oracle_VM_VirtualBox_Extension_Pack-4.1.12-77245.vbox-extpack'
libproxy suggest to use 'direct://'
--2012-04-14 20:30:42-- http://dlc.sun.com.edgesuite.net/virtualbox/4.1.12/Oracle_VM_VirtualBox_Extension_Pack-4.1.12-77245.vbox-extpack
Resolving dlc.sun.com.edgesuite.net... 24.244.17.82, 24.244.17.113
Connecting to dlc.sun.com.edgesuite.net|24.244.17.82|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 10062236 (9.6M) [application/x-virtualbox-vbox-extpack]
Saving to: "Oracle_VM_VirtualBox_Extension_Pack.tgz"
100%============================================================================================>] 10,062,236 2.13M/s in 4.5s
2012-04-14 20:30:47 (2.15 MB/s) - "Oracle_VM_VirtualBox_Extension_Pack.tgz" saved [10062236/10062236]
- installing Oracle VM VirtualBox Extension Pack 4.1.12r77245
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%
Successfully installed "Oracle VM VirtualBox Extension Pack".
It is also included in package vmscripts, available in my repo (see last post in the thread linked above).
Actually it would be easy to run this script automatically after a virtualbox update … but I don’t have time for that. Typing VboxExtensionPack one a month or so is not a big deal either.
I have a similar situation to the original poster.
I’ve installed Virtual Box 4.1.18 from Oracle and downloaded the Extension Pack for 4.1.18 as well. If I open a root terminal and type "VBoxExtensionPack all that I get is command not found and nothing happens at all. Clicking on the extension Pack just opens Ark.
Each time you install or update VirtualBox, you must go into the Preferences and add in the correct extension pack version to so that both the VirtualBox application and Extension Pack match (Virtual Box / File / Preferences / Extensions). Anytime you run a VirtualBox VM, you should then update the Extension Pack version there as well to match. This last step of updating the VM may be delayed for a while, but at some point, features in the VM may stop working if the Extension Pack versions do not match.
That’s because it’s not installed. It’s a script included in package vmscripts (see this post on how to install it: Running Linux live CDs in disk-less virtual machines under VirtualBox - and type “12.1” instead of “11.4” in the repo URL. Once it is installed, you just need to type VBoxExtensionPack. One could also create a service to run trhis script and never worry about the extension pack anymore… or create a package that would install both (like ArchLinux AUR people do).