Can I create directories that don't exist while creating a new file in emacs?

In emacs, I create a file by visiting it with C-x C-f. Let's say I'd like to create /home/myself/new_directory/file.txt.

If new_directory does not exist yet, is there a way to have it get created during the creation of file.txt without any extra steps? (I'm thinking of something like using the -p flag to mkdir in Linux.)

I feel like there's a different keystroke instead of C-x C-f that can do this, but I can't remember what it is.

You can also advise function find-file to transparently create necessary directories.

(defadvice find-file (before make-directory-maybe (filename &optional wildcards) activate)
  "Create parent directory if not exists while visiting file."
  (unless (file-exists-p filename)
    (let ((dir (file-name-directory filename)))
      (unless (file-exists-p dir)
        (make-directory dir t)))))

Simply put this in your .emacs somewhere and use C-x C-f as usual.

When I supply a pathname with a nonexistent component, find-file (i.e. C-x C-f), gives me an extra message that says

Use M-x make-directory RET RET to create the directory and its parents

Since the file is not created until you first save the buffer, you can either run make-directory right after your new buffer comes up or you can do it any other time before you need to save the file. Then from the buffer that needs a directory, type M-x make-directory RET RET (it will prompt for the directory to create (the default is derived from the buffer's pathname); the second RET is to accept the default).

The Ido mode provides ido-find-file that is a replacement of find-file and gives you much more features. For instance, it allows you to create new directory meanwhile you open the file.

• Type C-x C-f as usual (which is remapped to ido-find-file),

• provide the non-existent path,

• press M-m which will prompt for the new directory to create,

• and then specify the file name to visit in the newly created directory.

My solution comes with a bonus: if you kill the buffer without saving it, Emacs will offer to delete those empty directories that were created (but only if they didn't exist before you invoked find-file):

;; Automatically create any nonexistent parent directories when
;; finding a file. If the buffer for the new file is killed without
;; being saved, then offer to delete the created directory or
;; directories.

(defun radian--advice-find-file-automatically-create-directory
    (original-function filename &rest args)
  "Automatically create and delete parent directories of files.
This is an `:override' advice for `find-file' and friends. It
automatically creates the parent directory (or directories) of
the file being visited, if necessary. It also sets a buffer-local
variable so that the user will be prompted to delete the newly
created directories if they kill the buffer without saving it."
  ;; The variable `dirs-to-delete' is a list of the directories that
  ;; will be automatically created by `make-directory'. We will want
  ;; to offer to delete these directories if the user kills the buffer
  ;; without saving it.
  (let ((dirs-to-delete ()))
    ;; If the file already exists, we don't need to worry about
    ;; creating any directories.
    (unless (file-exists-p filename)
      ;; It's easy to figure out how to invoke `make-directory',
      ;; because it will automatically create all parent directories.
      ;; We just need to ask for the directory immediately containing
      ;; the file to be created.
      (let* ((dir-to-create (file-name-directory filename))
             ;; However, to find the exact set of directories that
             ;; might need to be deleted afterward, we need to iterate
             ;; upward through the directory tree until we find a
             ;; directory that already exists, starting at the
             ;; directory containing the new file.
             (current-dir dir-to-create))
        ;; If the directory containing the new file already exists,
        ;; nothing needs to be created, and therefore nothing needs to
        ;; be destroyed, either.
        (while (not (file-exists-p current-dir))
          ;; Otherwise, we'll add that directory onto the list of
          ;; directories that are going to be created.
          (push current-dir dirs-to-delete)
          ;; Now we iterate upwards one directory. The
          ;; `directory-file-name' function removes the trailing slash
          ;; of the current directory, so that it is viewed as a file,
          ;; and then the `file-name-directory' function returns the
          ;; directory component in that path (which means the parent
          ;; directory).
          (setq current-dir (file-name-directory
                             (directory-file-name current-dir))))
        ;; Only bother trying to create a directory if one does not
        ;; already exist.
        (unless (file-exists-p dir-to-create)
          ;; Make the necessary directory and its parents.
          (make-directory dir-to-create 'parents))))
    ;; Call the original `find-file', now that the directory
    ;; containing the file to found exists. We make sure to preserve
    ;; the return value, so as not to mess up any commands relying on
    ;; it.
    (prog1 (apply original-function filename args)
      ;; If there are directories we want to offer to delete later, we
      ;; have more to do.
      (when dirs-to-delete
        ;; Since we already called `find-file', we're now in the buffer
        ;; for the new file. That means we can transfer the list of
        ;; directories to possibly delete later into a buffer-local
        ;; variable. But we pushed new entries onto the beginning of
        ;; `dirs-to-delete', so now we have to reverse it (in order to
        ;; later offer to delete directories from innermost to
        ;; outermost).
        (setq-local radian--dirs-to-delete (reverse dirs-to-delete))
        ;; Now we add a buffer-local hook to offer to delete those
        ;; directories when the buffer is killed, but only if it's
        ;; appropriate to do so (for instance, only if the directories
        ;; still exist and the file still doesn't exist).
        (add-hook 'kill-buffer-hook
                  #'radian--kill-buffer-delete-directory-if-appropriate
                  'append 'local)
        ;; The above hook removes itself when it is run, but that will
        ;; only happen when the buffer is killed (which might never
        ;; happen). Just for cleanliness, we automatically remove it
        ;; when the buffer is saved. This hook also removes itself when
        ;; run, in addition to removing the above hook.
        (add-hook 'after-save-hook
                  #'radian--remove-kill-buffer-delete-directory-hook
                  'append 'local)))))

;; Add the advice that we just defined.
(advice-add #'find-file :around
            #'radian--advice-find-file-automatically-create-directory)

;; Also enable it for `find-alternate-file' (C-x C-v).
(advice-add #'find-alternate-file :around
            #'radian--advice-find-file-automatically-create-directory)

;; Also enable it for `write-file' (C-x C-w).
(advice-add #'write-file :around
            #'radian--advice-find-file-automatically-create-directory)

(defun radian--kill-buffer-delete-directory-if-appropriate ()
  "Delete parent directories if appropriate.
This is a function for `kill-buffer-hook'. If
`radian--advice-find-file-automatically-create-directory' created
the directory containing the file for the current buffer
automatically, then offer to delete it. Otherwise, do nothing.
Also clean up related hooks."
  (when (and
         ;; Stop if there aren't any directories to delete (shouldn't
         ;; happen).
         radian--dirs-to-delete
         ;; Stop if `radian--dirs-to-delete' somehow got set to
         ;; something other than a list (shouldn't happen).
         (listp radian--dirs-to-delete)
         ;; Stop if the current buffer doesn't represent a
         ;; file (shouldn't happen).
         buffer-file-name
         ;; Stop if the buffer has been saved, so that the file
         ;; actually exists now. This might happen if the buffer were
         ;; saved without `after-save-hook' running, or if the
         ;; `find-file'-like function called was `write-file'.
         (not (file-exists-p buffer-file-name)))
    (cl-dolist (dir-to-delete radian--dirs-to-delete)
      ;; Ignore any directories that no longer exist or are malformed.
      ;; We don't return immediately if there's a nonexistent
      ;; directory, because it might still be useful to offer to
      ;; delete other (parent) directories that should be deleted. But
      ;; this is an edge case.
      (when (and (stringp dir-to-delete)
                 (file-exists-p dir-to-delete))
        ;; Only delete a directory if the user is OK with it.
        (if (y-or-n-p (format "Also delete directory `%s'? "
                              ;; The `directory-file-name' function
                              ;; removes the trailing slash.
                              (directory-file-name dir-to-delete)))
            (delete-directory dir-to-delete)
          ;; If the user doesn't want to delete a directory, then they
          ;; obviously don't want to delete any of its parent
          ;; directories, either.
          (cl-return)))))
  ;; It shouldn't be necessary to remove this hook, since the buffer
  ;; is getting killed anyway, but just in case...
  (radian--remove-kill-buffer-delete-directory-hook))

(defun radian--remove-kill-buffer-delete-directory-hook ()
  "Clean up directory-deletion hooks, if necessary.
This is a function for `after-save-hook'. Remove
`radian--kill-buffer-delete-directory-if-appropriate' from
`kill-buffer-hook', and also remove this function from
`after-save-hook'."
  (remove-hook 'kill-buffer-hook
               #'radian--kill-buffer-delete-directory-if-appropriate
               'local)
  (remove-hook 'after-save-hook
               #'radian--remove-kill-buffer-delete-directory-hook
               'local))

Canonical version here.