You seem to be pressing Ctrl, W and | all together. That is incorrect. You should do
release both Ctrl and W,
and only then hit |.
I was really surprised to see that pressing Ctrl-W-= all together worked on the other hand.
Writing a compiler plugin allows you to supplement the :make command to run any tool you want, and parse the output into the quickfix window. In your case, I would so something like the following:
let current_compiler = 'shellcheck'
if exists(':CompilerSet') != 2
Sounds like you want to use the quickfix window. I only had moderate success with it in python, but it was all configured by a plugin. I also tried a bit with latex files. I never tried to set up vim for bash, so I don't know any plugin.
Wrote function that satisfied my needs. It checks total screen width and sets width, position and show-on-start of panels depending on result.
" Adjust side panels to screen resolution and ratio.
let screen_width = &columns " full screen size
let main_window_width = 82 + &foldcolumn " desired main window ...