Re: M-x shell question

[Roland Winkler <winkler@gnu.org>]

On Wed, Aug 17 2016, Andreas Schwab wrote:
> Emacs doesn't know what the shell is currently running, sending a cd
> command may not do what you want.

For many years I have been using the command below.  If the shell
appears to be busy, this command puts "cd dir" into the input history,
which makes the shell command available via comint-previous-input.


(defun my-shell (&optional buffer)
  "Use `default-directory' of current buffer as working dir of `*shell*' buffer.
Also, switch to `*shell*' buffer.
Optional arg BUFFER has same meaning as for command `shell'."
  (interactive ; code taken from `shell'
   (list
    (if current-prefix-arg
        (read-buffer "Shell buffer: "
                     (generate-new-buffer-name "*shell*")))))
  (unless default-directory
    (error "default-directory of current buffer is nil"))
  (let ((edir (expand-file-name default-directory))
        (cdir (concat "cd " (abbreviate-file-name default-directory))))
    (shell (get-buffer-create (or buffer "*shell*")))
    ;; change directory, unless we are already where we want to be
    (unless (string= edir (expand-file-name default-directory))
      (goto-char (point-max))
      (if (looking-back comint-prompt-regexp nil)
          (progn (insert cdir)
                 (comint-send-input))
        (message "shell `%s' seems to be busy, cannot change directory"
                 (buffer-name))
        (comint-add-to-input-history cdir)))))