The first tip works because : is a bash builtin that just returns 0, so all the comments are unused arguments. The copy/paste warning example is nice but I can't find ant other usecases for it.

The coprocess look very interesting, just yesterday I spent 2 hours trying setting up a bash script with 2 tasks: 1. open mupdf 2. recompile a pdf when sources change, and then send an update signal to mupdf

I ended up giving up because the signalling was too complex for such a simple idea and installed a latex plugin in vim. I'm excited to try again with coprocesses!