automagically /aw-toh-maj'i-klee/ adv.
in a way that, for some reason (typically because it is too
complicated, or too ugly, or perhaps even too trivial), the speaker
doesn't feel like explaining to you. See magic. "The
C-INTERCAL compiler generates C, then automagically invokes
cc(1) to produce an executable."
This term is quite old, going back at least to the mid-70s in jargon and probably much earlier. The word `automagic' occurred in advertising (for a shirt-ironing gadget) as far back as the late 1940s.