Well 'ack' is even shorter, and the common form of 'ACKNOWLEDGED' for such use. I've seen & used both ack & wilco in a technical/software chat context.
I use this, though I find that many folks, including many technical folks, interpret it as an exclamation of distaste (as in, "agh! ach! ack!"), so it may pay to be judicious.
Oh interesting, I have come across that, but only one person (both uses it like that and misinterpreted it when we worked with people that ack'd, which of course I saw coming & could explain since I was accustomed to his use) - didn't realise that was common too. (I would use agh/argh/ugh for that personally, depending on precise feeling(!))