Sometimes it may happen that we would like to open the current buffer in another text editor (notepad, gedit, texmaker, ....). What are the best ways to do it?

  • Are you talking about sending the current buffer text as well? – Sean Allred Jan 10 '15 at 3:32
  • 2
    "But why would you want to?" :( – Lily Chung Jan 10 '15 at 6:25
  • @IstvanChung It may happen! For example you are editing an HTML file and you would like to open it in a web browser, also for the case where your language is not supported by the spell-checking engines of Emacs. And many other examples. – Name Jan 10 '15 at 9:37
  • @SeanAllred yes. – Name Jan 10 '15 at 9:40

You could use something such as the following

(defun open-external (&optional editor)
  (interactive "sEditor to use: ")
  (let ((file (buffer-file-name (current-buffer))))
    (if (executable-find editor)
        (if file
            (shell-command (format "%s %s"
                                   (executable-find editor)
          (user-error "Current buffer has no associated file."))
      (user-error "Editor (%s) not found on path" editor))))

This uses buffer-file-name rather than buffer-name to ensure you get the associated file from the filesystem. It also validates that both the file and the editor selected are found on path (or explicitly pointed to).

  • Nice! Hadn't known about executable-find. – Dan Jan 9 '15 at 21:22
  • I think you can simplify this by dropping the let call. You can access the buffer-file-name directly as a variable, you don't need to call it and store the value. – robru Jan 11 '15 at 18:53
  • The let is more personal preference. Have to access file twice so rather use a temporary variable than type it out fully both times. – Jonathan Leech-Pepin Jan 21 '15 at 14:37
  • A few remarks (only the first has some importance) (i) I suggest using call-process instead of shell-command, otherwise you'd have to quote the filename for the shell. (ii) as was pointed out, buffer-file-name is also a variable name, which you can use directly (as for the function, (current-buffer) is used by default) (iii) you could define a temporary variable for (executable-find editor) too (I don't know how costly that function call is, but I guess this is more than a call to the function buffer-file-name !) – YoungFrog May 13 '15 at 8:49

This version opens the buffer in an external program (use a prefix to change the default). If the buffer is not visiting a file, open it up in a temporary file:

(defvar alternate-editor "gedit"
  "Editor to use when visiting a buffer outside of emacs.")

(defun open-in-alternate-editor (&optional arg)
  "Open buffer in alternative editor.  If buffer is unsaved,
bring it up in a temporary file.  With prefix argument, ask for
the editor to use."
  (interactive "P")
  (let ((edit (executable-find (if arg
                                    "Enter editor to use: "
        (file (or (buffer-file-name)
                  (make-temp-file "unsaved-emacs-buffer-")))
        (buff (unless (buffer-file-name)
                (save-restriction (widen) (buffer-string)))))
    (when (null edit)
      (error "Can't find alternate editor"))
    (unless (buffer-file-name)
      (with-temp-file file
        (insert buff)))
    (start-process "Alternate Editor" nil edit file)))

Note that the defvar might be overkill -- you could just replace it with whatever string you like within the defun.


M-! (shell-command)

You could for example define your own command for edit that takes the current buffer name as input

(defun ppop-open-in-gedit ()
  (interactive "")
  (shell-command (format  "gedit %s" (buffer-file-name))))

(global-set-key (kbd "<f10>") 'ppop-open-in-gedit)

I would check if the buffer has a corresponding file, but you get the idea.

  • 2
    (buffer-file-name) is better than (buffer-name (current-buffer)) here. They both default to the current buffer, so you don't need to specify it explicitly. – Tyler Jan 9 '15 at 20:55

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