22

how to change the current working directory of emacs?

set default-directory doesn't not affect the emacs process's current working directory, which can be verified via lsof -p pid.

Improve this question
2
  • 1
    Emacs, being "a kind of OS" doesn't really have a single current working directory. So what you see as the process's cwd is largely accidental and not really documented. Looking at Emacs's C code, I get the impression that there is currently no way to do what you want. You might hence M-x report-emacs-bug and request it as a new feature.
    – Stefan
    Commented Nov 21, 2017 at 18:47
  • 2
    Assuming you are on Linux, you could force the cwd to change by working at OS level, see unix.stackexchange.com/questions/281994/… for details.
    – TTimo
    Commented Sep 25, 2018 at 14:54

4 Answers 4

Reset to default
7

I think the only way Emacs offers to control the cwd of the process is the --chdir command line argument. Once the process is started, there is currently no way to modify it.

Improve this answer
2
  • This is wrong. M-x cd command does change the current working directory. It even makes find-file to iniially suggest the given directory to look for files in.
    – Sventimir
    Commented Dec 20, 2021 at 21:48
  • 2
    M-x cd does not change the working directory of the Emacs process (which can be seen in /proc/<PID>/cwd under Linux, for example), it only changes the directory used by ELisp code (and subprocesses it may spawn).
    – Stefan
    Commented Dec 22, 2021 at 0:18
39

M-x cd

This should solve your problem.

Improve this answer
2
  • 3
    According to the docs, cd will "Make DIR become the current buffer's default directory." I would presume that it's a per-buffer value and wouldn't apply to other existing buffers or to newly created ones.
    – mojo
    Commented Feb 14, 2019 at 14:52
  • @mojo perhaps, but if you do that with the default buffer when all your other buffers are closed that's all you're left with anyway. So it's still quite practical
    – Keldon Alleyne
    Commented Mar 4, 2020 at 1:33
9

C-h f cd:

cd is an interactive compiled Lisp function in files.el.

(cd DIR)

Make DIR become the current buffer’s default directory.

If your environment includes a CDPATH variable, try each one of that list of directories (separated by occurrences of path-separator) when resolving a relative directory name. The path separator is colon in GNU and GNU-like systems.

And please explain why changing default-directory does not also change the "current directory" for you: (setq default-directory "/my/favorite/dir").

Improve this answer
4
  • 1
    I mean the cwd of the emacs process, which is an entry in the process control block, and it can be easily checked via =lsof -p pid=. The =default-directory= is an internal thing to emacs. Why I need to change cwd is because tmux uses the cwd of a foreground process as the start directory of a new window/pane.
    – FunkyBaby
    Commented Nov 21, 2017 at 3:05
  • I see. Then your question was (and still is, to me) unclear. What does it mean to change the current working directory of the Emacs process? You want to change it after the process exists? More than once?
    – Drew
    Commented Nov 21, 2017 at 3:09
  • 1
    it is literally changing the =cwd= of emacs. "More than once"? what do you mean by that. =cwd= is not designed to be a fixed thing. In c, man 2 chdir. In python, os.chdir. I want to know how to do that in elisp (for emacs).
    – FunkyBaby
    Commented Nov 21, 2017 at 14:57
  • See @Stefan's answer.
    – Drew
    Commented Nov 21, 2017 at 19:33
1

Maybe not an answer to the question but I had a similar issue. The setup was emacsclient over tmux session and had to split the window horizontally and open a new tmux tab with the current Emacs' working directory. Here is a workaround:

init.el:

;;; Tmux integration (See tmux.conf for details).

(defun id/tmux-split-horisontal ()
  "Split tmux pane horisontally."
  (interactive)
  (ignore-errors (call-process "tmux" nil nil nil "split-window" "-h" "-c"
                               default-directory)))

(global-set-key (kbd "C-q %") #'id/tmux-split-horisontal)

(defun id/tmux-new-tab ()
  "Create new tmux tab."
  (interactive)
  (ignore-errors (call-process "tmux" nil nil nil "new-window" "-c"
                               default-directory)))

(global-set-key (kbd "C-q c") #'id/tmux-new-tab)

tmux.conf:

## Use C-q as a prefix key.
unbind C-b
set -g prefix C-q
bind C-q send-prefix

## Handle [C-q %] and [C-q c].
is_emacs='echo "#{pane_current_command}" | grep -iqE "emacs"'

# Let Emacs handle [C-q %] if active.
bind-key -T prefix % if-shell "$is_emacs" "send-prefix ; send-keys %" "split-window -h -c \"#{pane_current_path}\""
# Let Emacs handle [C-q c] if active.
bind-key -T prefix c if-shell "$is_emacs" "send-prefix ; send-keys c" "new-window -c \"#{pane_current_path}\""

In this way, if you're under emacs or emacsclient the control is passing to Emacs, thus Emacs sends tmux command with default-directory argument. Otherwise, tmux handles it directly, so the user doesn't see the difference.

Improve this answer

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.