Shut it down. Shutting down.
(Shutting up?)
That depends on the direction of the opening. Shut up means basically the same thing as shut down, but the hinged part operates in the opposite direction.
Yeah, just shut works for either. It’s less so redundancy and more specificity.
If you think about it, there’s only meaning with a frame of reference. Shutting up or shutting down could be nonsensical in the Void, as many things would be, I imagine.
Shut the door, or close the window. Which came first, Doors or Windows?.. 🤔