Gnuclient allows you to edit files using an already running Emacs or XEmacs. It is part of XEmacs. The program EmacsClient shipped with GnuEmacs supports similar functionality and as of Emacs 22.1 supports all of the features and platforms that Gnuclient does, therefore the rest of this page applies to GNU Emacs 21.4 and earlier for users who require functionality beyond simple file loading (and XEmacs, of course).

You could use this as your external editor from Mozilla using the appropriate extension, for example.

Older versions:

For a newer version modified for MS Windows see below.

Emacs already has such a utility: EmacsClient (starting from GnuEmacs 22.1 also on Microsoft Windows). The problem with emacsclient is that with versions prior to and including 21.4 you cannot use it to execute arbitrary elisp code. This is necessary if you want to use Emacs to follow mailto links, for example.

To install, add the following to your init file:

    (load "gnuserv")

If you are download the alpha version available on that web site, make sure that you configure the gnuserv.h correctly about the connection mechanism you prefer. It has three options, SYSV_IPC,INTERNET_DOMAIN_SOCKETS and UNIX_DOMAIN_SOCKETS. If you use the default, it will be compiled with INTERNET_DOMAIN_SOCKETS. In this case, you need to have an environment variable called GNU_SECURE which will point to a file which in turn contains the list of hosts (one per line) that are trusted. This is a security mechanism. I would have expected the localhost to work properly but for some reason, on my machine, this was failing with “Refused connection to <my m/c IP>” in the buffer for emacs. After I added GNU_SECURE part, it seems to work OK. HTH --GirishB


A newer version of gnuserv/client can be found here:

Windows users read the FAQ:

With emacs 21.3.1 and windows 98 the following init file lines (rather than the ones in the previous section) were needed for installation:

    (load-library "gnuserv")
    (setq gnuserv-frame (selected-frame))

winclient, a DDE client for XEmacs, is part of the native Windows build since

(but there doesn’t seem to be documentation for winclient.exe or hooks for winclient-edited files?)

Installing with stow

Stow is a utility that allows you to maintain packages installed in the /usr/local tree. This sequence of commands works fine:

    # I need this to put Emacs on the root PATH:
    export PATH=$PATH:/usr/local/bin
    mkdir -p /usr/local/stow/gnuserv/bin
    cp gnuclient gnudoit gnuserv /usr/local/stow/gnuserv/bin/
    mkdir -p /usr/local/stow/gnuserv/man/man1
    cp *.1 /usr/local/stow/gnuserv/man/man1
    mkdir -p /usr/local/stow/gnuserv/share/emacs/site-lisp
    cp *.el /usr/local/stow/gnuserv/share/emacs/site-lisp
    cd /usr/local/stow
    stow gnuserv

Get Stow here:

XEmacs and stow

If you have both Emacs and XEmacs installed, and you are using stow to maintain the packages, then the gnuserv package will conflict with the XEmacs package – the three executables and the manpage are the same. I just deleted the XEmacs versions:

    rm /usr/local/stow/xemacs/bin/gnu*
    rm /usr/local/stow/xemacs/man/man1/gnu*

I didn’t try to just use the gnuserv package that came with XEmacs. Has anybody tried?

gnuclient not starting a new emacs

Here is a script to do use gnuclient when Emacs is already using and to start Emacs otherwise:


    instanceCount=$(ps aux | grep xemacs | grep -v 'grep xemacs' | wc -l);
    if [ "$instanceCount" -eq "0" ]; then
            xemacs "$@" &
            gnuclient -q "$@"


For Emacs-21 emacsclient, you may just say

emacsclient -a emacs "$@"

In fact, you could call even call vi if Emacs was not up.

When I open a gnuclient window, I don’t think of it as being bound to a particular buffer, so I don’t like it to close itself when I close that buffer. This script lets you open files from the shell without them becoming owned by gnuclient. – AdrianKubala

I use a slightly edited version of the above on my system. It only checks for emacs processes running as your user (which is useful if you occaisonally edit system files as root too). Also it doesn’t background ever. You’ll probably need to change the 3rd line to point at the right version of emacs. Personally, I run debian, so this is saved as /usr/local/bin/emacs and I use the alternatives system to point /usr/bin/emacs at this script.



    ps x | grep "[^]] $emacs"
    if [ "$?" -eq "0" ]; then
        $gnuclient -q "$@"
        $emacs "$@"


    if [[ -n "$file" ]]; then
     if [[ ${file:0:1} != "/" ]]; then file="`pwd`/$file"; fi
     gnuclient -batch -eval "(find-file-other-frame \"$file\")" > /dev/null
     gnuclient -batch -eval "(new-frame)"  > /dev/null

A small improvement : if gnuclient fails, launch xemacs . – jeyries

for file in $@ ; do
    if [[ ${file:0:1} != "/" ]]; then file="$PWD/$file"; fi 
    cmd="$cmd (find-file \"$file\")";      
if [[ -z "$cmd" ]]; then

gnuclient -batch -eval "$cmd"  > /dev/null 2> /dev/null
if (( $? )); then
    xemacs $* & 

On the console

You can use gnuclient on the console, too, although usage is a bit weird. On one terminal, start Emacs. Switch to another terminal, call gnuclient with a filename. The screen goes blank. Now switch back to the first terminal and note that Emacs opened the correct file. Edit, finish, switch to the second terminal and continue working.

If you find this procedure confusing, you are not alone. Alas, GnuEmacs cannot currently handle two different display types at the same time. Fortunately this is issue is being resolved, see MultiTTYSupport. XEmacs has no such problems.

For an alternative to MultiTTYSupport which is less elegant but without the need to patch your emacs, you may want to have a look at ScreenServer.

Reusing Frames

Set ‘gnuserv-frame’ to the frame you want to use. Here is something you might want:

    (setq gnuserv-frame (selected-frame))

This will force gnuclient to keep using the same frame over and over. This is a problem if you ever delete the original first frame -- because then gnuserv-frame points to a nonexisting frame.

You can also get a little more fancy and try this:

    (setq gnuserv-frame (lambda (f) (eq f (quote x))))

When you are running from an emacs in X, that will cause it to open in the same frame. But if you run it on a TTY, then it will open a new frame.

Reusing Frames And Popping The Frame To The Foreground

In order to reuse the same frame, and raise it to the foreground, you can just advise the ‘server-find-file’ and ‘server-edit’. Note the addition of ‘raise-frame’. Note also that the ‘lower-frame’ call might not do what you expect; at least when using the ratpoison window manager, I do not get popped back to the last window I used (which called gnuclient). The following also makes sure that ‘gnuserv-frame’ always points to an existing frame.

    (defadvice server-find-file (before server-find-file-in-one-frame activate)
      "Make sure that the selected frame is stored in `gnuserv-frame', and raised."
      (setq gnuserv-frame (selected-frame))
    (defadvice server-edit (before server-edit-in-one-frame activate)
      "Make sure that the selected frame is stored in `gnuserv-frame', and lowered."
      (setq gnuserv-frame (selected-frame))

I do something I think is simpler and better (part of it is RP-only):

    (load-file "~/ratpoison/contrib/ratpoison-cmd.el")
    (add-hook 'server-switch-hook 'raise-frame)
    (add-hook 'server-done-hook 'ratpoison-prev)

Reusing only visible frames already containing the file

If you use InverseSearch with xdvi, it is often the case that the purpose of invoking gnuclient is not to start editing a new file but to move the point in the already edited file. A sensible solution is to have gnuclient reuse a visible frame already containing the file, and open a new one only if necessary. Define

    (defun local-gnuserv-open(filename lineno)
      (let ((buffer (find-file-noselect (file-truename filename)))
            (pop-up-frames t)
            (display-buffer-reuse-frames t))
        (set-buffer buffer)
        (select-window (display-buffer buffer nil 0))
        (goto-line lineno)

and invoke gnuclient like this

gnuclient -q -batch -eval "(local-gnuserv-open \"$filename\" $lineno)"

invoking dired from xterm

alias dired=’gnudoit “(progn (select-frame (make-frame-on-display \”$DISPLAY\”)) (dired \”$(pwd)\”))”’

Only one copy of the file being edited

One of the nicest things with GnuClient is mentioned here just as a byproduct. I believe that is because Emacs users are often used to work from within Emacs. Coming from (still there) MS Windows I work most often in another way. From the command line (most often) I give a command to edit a file. Then I want my editor of choice to first look for an already opened copy of that file. (It should not behave like Notepad.) This is what GnuClient does for me.

See also the variables find-file-visit-truename and find-file-existing-other-name.

Launching Frames from Emacs Running as a Daemon Server

[Originally, on WishList article.]

Using GnuClient and PuTTY for Latin-1 characters input

The following assumes that the terminal and shell are 8-bit clean.

Place in your .xemacs/init.el:

;; Allow Latin-1 from ssh as raw
(defun njsf-input-tty-mode ( &optional console )
  "Set the eight bit to raw"
  (interactive "")
  (let ((cur-console (selected-console)))
    (when console
      (select-console console))
    (set-input-mode nil nil 0)
    (when cur-console
      (select-console cur-console))))

(add-hook 'create-console-hook 'njsf-input-tty-mode t)
(add-hook 'after-init-hook 'njsf-input-tty-mode t)

It is assumed you started a gnuserv session previously before reaching these steps.

Set in the PuTTY configuration: Terminal / Keyboard / Backspace key / Control-? (127) (This way Backspace is Backspace and not C-h for help)

After connect I advise:

$ stty erase C-v BS

This should have the effect of showing in prompt

stty erase ^?

To use gnuclient you can use:

$ gnuclient -nw

And now you can type Latin-1 caracters directly.

Piping data to an Emacs buffer

Here is a perl script I call emacs-pipe, for piping data to an Emacs buffer.

#! /usr/bin/perl

## This script uses gnudoit to put the contents of STDIN
## in an Emacs buffer called *Piped*

if (! `which gnudoit 2>/dev/null`) {
  print STDERR "This script requires gnudoit\n";

while(<STDIN>){ $foo .= $_; }
$foo =~ s/(["\\])/\\$1/g;
open(GNUDOIT, "|gnudoit -q");
print GNUDOIT <<EOF;

 (get-buffer-create "*Piped*")
 (delete-region (point-min) (point-max))
 (insert "$foo"))


Getting gnuserv running on GNU Emacs 21.3.1 for Windows

What and how to install to be able to use gnuserv on emacs running on Windows?

Assumption: You already have a running emacs.


  1. Download .
  2. From the zip file, extract gnuserv.exe, gnuclientw.exe, gnuclient.exe into your ‘bin’ dir of your existing emacs installation.
  3. add the following into your InitFile.
(load "gnuserv")

From now on you should start emacs using ‘gnuclientw.exe’ found in your ‘bin’ dir of emacs installation and it should load and run gnuserv by itself.

In case you get an error like .

...Could not find emacs_dir in Registry (searched HKCU and HKLM )...

You can run addpm.exe in your ‘bin’ directory of your emacs installation, though this error may be quite harmless.

Hope somebody finds it helpful.


Bug: Delay in "activation" of CUA mode or IDO mode

I use Guy Gascoigne's Windows port of gnuserv with Emacs 22.1.1 for Windows. In my .emacs file, I have

    (load "gnuserv")
    (setq gnuserv-frame (selected-frame))

making use of the file gnuserv.el, which I have placed in my site-lisp directory. Furthermore, in my bin directory I have placed, together with the usual Emacs .exe files, the files gnuclient.exe, gnuclientw.exe, gnudoit.exe and gnuserv.exe. Thus, I can open files “with” Emacs by passing them to gnuclientw.exe. That is, in the “Open file with …” dialog I select gnuclientw.exe, and in my SendTo folder I have a shortcut to gnuclientw.exe. It works!

However, there is a slight problem when using CUA mode or IDO mode (and perhaps other modes as well). I’m fond of both, so in my .emacs file I also have

    (cua-mode t)
    (setq cua-enable-cua-keys nil)
    (require 'ido)
    (ido-mode t)

Now, if I start Emacs by clicking on a file it’s associated with, some aspects of CUA mode and IDO mode will not immediately work! For instance, CUA mode activates transient mark mode, but when setting the mark, no highlighting of the region occurs. Similarly, no auto-completion is provided by IDO mode when finding files with C-x C-f. However, neither of these are lasting problems. After about a minute, highlighting of the region is “turned on”, and IDO mode becomes active when finding files. What is going on here?

I’ve found that the delay is probably related to the start-up message. When starting up Emacs the ordinary way, the Emacs logo and some helpful clues are displayed for about the same amount of time. After that, Emacs switches to the *scratch* buffer. Similarly, at the precise moment when CUA mode and IDO mode are fully “activated”, some “refreshing” of the buffer seems to take place – akin to the refreshing of a web page in a web browser.

Finally, I’ve found that deactivating the start-up message makes the problem disappear:

    (setq inhibit-startup-message t)

When the line above is added to .emacs, there is no delay in the “activation” of CUA mode and IDO mode when opening files with gnuclientw.exe – in my experience, they both work flawlessly now.

I provide this information to aid those Windows users who, like me, use Guy Gascoigne’s Windows port of gnuserv (which is actually the patched version of gnuserv that previously came with EmacsW32) instead of the EmacsW32 project’s patched version of Emacs. There might be better ways to deal with this bug than the fix I’ve described here.