On saving a file, whitespace-cleanup does a nice job of cleaning up whitespace:
https://emacsredux.com/blog/2013/05/16/whitespace-cleanup/
However, I would like to be able to leave a blank line at the end of buffer, either globally or add a hook for different modes.
I think if I edit this whitespace-empty-at-eob-regexp I should be able to do it?
whitespace-empty-at-eob-regexp’s value is "^\\([ ]+\\)\\'"
So I thought I could just add a \n but this does not achieve what I want:
"^\\([ ]+\\n\)\\'"
The value of whitespace-empty-at-eob-regexp is "^\\([ \t\n]+\\)\\'" actually.
I you want to leave a blank line at the end of buffer. Try:
(setq whitespace-empty-at-eob-regexp "^[ \t\n]\\([ \t\n]+\\)\\'")
;; Tips: you can use xr and rx to play with regex more relaxed in emacs.
;; (xr "^[ \t\n]\\([ \t\n]+\\)\\'")
;; (seq bol
;; (any "\t\n ")
;; (group
;; (one-or-more
;; (any "\t\n ")))
;; eos)