unattended-save-some-buffers.el

;; Gits URL: https://gist.github.com/jamescherti/095812fefed49894cde5e5945ce5d63a
;; License: MIT
;; Author: James Cherti
;;
;; Description: 
;; ------------
;; Make the built-in (save-some-buffers) function automatically save 
;; buffers that are visiting existing files, without prompting the 
;; user for confirmation.

(defun my-buffer-save-without-query-when-file-exists ()
  "Set buffers visiting existing files to save without querying the user."
  (let ((file-name (buffer-file-name)))
    (when (and file-name (file-exists-p file-name))
      (setq buffer-save-without-query t))))

(add-hook 'find-file-hook #'my-buffer-save-without-query-when-file-exists)