An apparatus for executing one or more commands, for use with a virtualization environment operable to execute one or more virtualization functions, the apparatus comprising: an interface operable to determine an identifier associated with a first virtualization function; a parser operable to determine one or more commands available for execution using the first virtualization function; a store for storing each determined command with the first virtualization function identifier; a searcher, responsive to input of a first command, for matching the first command with each determined command in order to determine one or more matching commands; and an executor, responsive to selection of a first matching command, for executing the associated first virtualization function and the first matching command.