Emacs 26.3(2020-04-03)具有重命名文件功能，可以使用M-x重命名文件来重命名当前文件或任何其他文件。

试试Steve Yegge的.emacs中的这个函数:

;; source: http://steve.yegge.googlepages.com/my-dot-emacs-file
(defun rename-file-and-buffer (new-name)
  "Renames both current buffer and file it's visiting to NEW-NAME."
  (interactive "sNew name: ")
  (let ((name (buffer-name))
        (filename (buffer-file-name)))
    (if (not filename)
        (message "Buffer '%s' is not visiting a file!" name)
      (if (get-buffer new-name)
          (message "A buffer named '%s' already exists!" new-name)
        (progn
          (rename-file filename new-name 1)
          (rename-buffer new-name)
          (set-visited-file-name new-name)
          (set-buffer-modified-p nil))))))

看一下那个页面，那里有另一个非常有用的相关函数，叫做“move-buffer-file”。

下面是一个改编自史蒂夫的更健壮的版本。

;; Originally from stevey, adapted to support moving to a new directory.
(defun rename-file-and-buffer (new-name)
  "Renames both current buffer and file it's visiting to NEW-NAME."
  (interactive
   (progn
     (if (not (buffer-file-name))
         (error "Buffer '%s' is not visiting a file!" (buffer-name)))
     ;; Disable ido auto merge since it too frequently jumps back to the original
     ;; file name if you pause while typing. Reenable with C-z C-z in the prompt.
     (let ((ido-auto-merge-work-directories-length -1))
       (list (read-file-name (format "Rename %s to: " (file-name-nondirectory
                                                       (buffer-file-name))))))))
  (if (equal new-name "")
      (error "Aborted rename"))
  (setq new-name (if (file-directory-p new-name)
                     (expand-file-name (file-name-nondirectory
                                        (buffer-file-name))
                                       new-name)
                   (expand-file-name new-name)))
  ;; Only rename if the file was saved before. Update the
  ;; buffer name and visited file in all cases.
  (if (file-exists-p (buffer-file-name))
      (rename-file (buffer-file-name) new-name 1))
  (let ((was-modified (buffer-modified-p)))
    ;; This also renames the buffer, and works with uniquify
    (set-visited-file-name new-name)
    (if was-modified
        (save-buffer)
      ;; Clear buffer-modified flag caused by set-visited-file-name
      (set-buffer-modified-p nil)))

  (setq default-directory (file-name-directory new-name))

  (message "Renamed to %s." new-name))

有一个很简单的方法，你按下命令M-x，然后键入vc-rename-file，之后你只需要在目录中选择你当前的文件，然后选择新的名称。已更改文件的buff将被刷新。

来源:https://www.gnu.org/software/emacs/manual/html_node/emacs/VC-Delete_002fRename.html

这是另一个版本，它非常健壮，并且支持VC:

(defun rename-file-and-buffer ()
  "Rename the current buffer and file it is visiting."
  (interactive)
  (let ((filename (buffer-file-name)))
    (if (not (and filename (file-exists-p filename)))
        (message "Buffer is not visiting a file!")
      (let ((new-name (read-file-name "New name: " filename)))
        (cond
         ((vc-backend filename) (vc-rename-file filename new-name))
         (t
          (rename-file filename new-name t)
          (set-visited-file-name new-name t t)))))))

你可以在这里阅读更多信息。

为了完整起见，由于有些人访问此页面时可能认为他们将得到Emacs的“另存为”特性的答案，对于打开的文件，这是C-x C-w。