How do I create an empty file in emacs?

问题:

How can I create an empty file from emacs, ideally from within a dired buffer?

For example, I've just opened a Python module in dired mode, created a new directory, opened that in dired, and now need to add an empty __init__.py file in the directory.

If I use C-x C-f __init__.py RET C-x C-s then emacs doesn't create the file because no changes have been made to it. I would have to type in the file, save it, delete my typing and then save it again for that to work.

Thanks

回答1:

Here's an adaptation of dired-create-directory. It works the same way, so as well as a plain filename, you can also specify new parent directories (to be created under the current directory) for the file (e.g. foo/bar/filename).

(eval-after-load 'dired
  '(progn
     (define-key dired-mode-map (kbd "C-c n") 'my-dired-create-file)
     (defun my-dired-create-file (file)
       "Create a file called FILE.
If FILE already exists, signal an error."
       (interactive
        (list (read-file-name "Create file: " (dired-current-directory))))
       (let* ((expanded (expand-file-name file))
              (try expanded)
              (dir (directory-file-name (file-name-directory expanded)))
              new)
         (if (file-exists-p expanded)
             (error "Cannot create file %s: file exists" expanded))
         ;; Find the topmost nonexistent parent dir (variable `new')
         (while (and try (not (file-exists-p try)) (not (equal new try)))
           (setq new try
                 try (directory-file-name (file-name-directory try))))
         (when (not (file-exists-p dir))
           (make-directory dir t))
         (write-region "" nil expanded t)
         (when new
           (dired-add-file new)
           (dired-move-to-filename))))))

回答2:

You can use the touch command:

M-! touch __init__.py RET

回答3:

The following works:

C-x b __init__.py RET C-x C-w RET

If you're in a dired buffer the file will be saved in the directory show here.

The trick is to first create an empty buffer by switching to a name that doesn't exist. Then write out the file.

回答4:

If you want Emacs to treat all new files as modified, you can automate the solution like this:

(add-hook 'find-file-hooks 'assume-new-is-modified)
(defun assume-new-is-modified ()
  (when (not (file-exists-p (buffer-file-name)))
    (set-buffer-modified-p t)))

回答5:

Emacs won't allow you to save a buffer unless it thinks the contents have changed. The quickest, though possibly not cleanest is to open the file using C-x C-f, then press (say) space and backspace, then you should be able to save a file with no contents.

There are other ways of changing the "buffer has been modified" flag, but I don't think there's any easier.

回答6:

Programatically and without any dependency on touch, it's quite easy:

(with-temp-buffer (write-file "path/to/empty/file/"))

回答7:

Use touch command.

M-! touch __init__.py RET

回答8:

The shortest way

M-! > __init__.py RET

回答9:

After this thread, Emacs has added two new commands:

1. make-empty-file
2. dired-create-empty-file

These commands will be available in the emacs 27.1 release.

回答10:

(shell-command (concat "touch " (buffer-file-name))) will do what you want, if you've already opened the empty file.

回答11:

In addition to other answers on the page, you can use f.el's function f-touch:

M-:(f-touch "__init__.py")RET

回答12:

You can mark an empty buffer as modified by running set-buffer-modified-p. Then when you save it, Emacs will write the file.

M-;                         ; Eval
(set-buffer-modified-p t)   ; Mark modified
C-x C-s                     ; Save buffer

回答13:

I use the following bound to t in dired.

(defun my-dired-touch (filename)
  (interactive (list (read-string "Filename: " ".gitkeep")))
  (with-temp-buffer
    (write-file filename)))

;; optionally bind it in dired
(with-eval-after-load 'dired
  (define-key dired-mode-map "t" 'my-dired-touch))

回答14:

I've modified answer from MrBones and created custom function with keybinding:

; create empty __init__.py at the place
(defun create-empty-init-py()
  (interactive)
  (shell-command "touch __init__.py")
)
(global-set-key (kbd "C-c p i") 'create-empty-init-py)

This is very useful to not spend time on recurring action of creating init.py everywhere in new Python project folder.

回答15:

The best option would be:

(with-temp-file "filename"
  (insert ""))