Thanks, Axel for your kind words, and also for your analysis. I've had a look at renameutils, of which I was not aware, though I have it installed on my machine already!
It seems to me that it covers interactive usage neatly, so I'd be happy to remove that from mmv, retaining the -n flag, but removing the ability to read renames from standard input. -- https://rrt.sc3d.org
