Question

I want to do the following in Emacs: Save the current buffer to a new file, but also keep the current file open.
When I do C-x C-w then current buffer gets replaced, but I want to keep open both buffer. Is this possible without reopening the original file?

Answer 1

I don’t think there’s anything built in, but it’s easy enough to write:

(defun my-clone-and-open-file (filename)
  "Clone the current buffer writing it into FILENAME and open it"
  (interactive "FClone to file: ")
  (save-restriction
    (widen)
    (write-region (point-min) (point-max) filename nil nil nil 'confirm))
  (find-file-noselect filename))