I noticed something interesting recently that might relate to a service install.  My WU is going too slow on my machine, so I was going to quit and see about a smaller one.  Since I was running the CLi, I just closed its window.  The interesting thing is, the CORE executable kept running; and it's still running! 

 Hidden! 
I don't know if the core will stop when it finishes a WU or not; I'd let you know, but it will take about three more days. 
P.S. About copying a file, I imagine one could redirect STDIN to the program from a file.  But I haven't tried that, either.