The learning curve for writing Lisp goes around, and up, and into hyperbolic space, and thru a Bathsheba Grossman industrial art piece and then after a decade or two of time spent in rooms with soft walls, you can start to manage basic things.
And so, twelve years after I started using emacs, I can now automate some of my more common tasks.
Back in the days when I had to use PFE under MSWin, the one thing I liked being able to do was that, when I would be running a command line, I could use "%f" in the command line and that would be replaced with the current file's filename.
I found nothing quite so convenient for Emacs. So I wrote it.
With this you can run command lines like "xslbong !! thingywhoozits" and it'll replace "!!" with the current buffer's filename. And incidentally, it'll save the output to a new scratch buffer, instead of the usual functions that just overwrite "*Shell Command Output*".
I'm a sophistatronic programmder!
(I chose "!!" as a string that I just happen never to use in command lines. Change it as you like.)