There is no way to control the input that a child receives (unless you specifically program or alter this spawned process). Since you'll need something other than the shell, emulating some sort of completion, Term::Complete is the way to go. Load the directory's contents into the requested array. You may also implement the allowed commands in a similar manner, snatching modules as you need them. Better yet, make a more user-friendly interface, perhaps with menus, perhaps graphical or Curses, to make it clear to the user exactly which options he has- limiting in a friendly manner!

AgentM Systems nor Nasca Enterprises nor Bone::Easy nor Macperl is responsible for the comments made by AgentM. Remember, you can build any logical system with NOR.