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GNUSERV(1)									       GNUSERV(1)

NAME
       gnuserv, gnuclient - Server and Clients for XEmacs

SYNOPSIS
       gnuclient  [-nw]  [-display  display] [-q] [-v] [-l library] [-batch] [-f function] [-eval
       form] [-h hostname] [-p port] [-r remote-pathname] [[+line] file] ...
       gnudoit [-q] form
       gnuserv
       gnuattach Removed as of gnuserv 3.x

DESCRIPTION
       gnuserv is a server program run as a subprocess of XEmacs to handle all incoming and  out-
       going  requests	from  gnuclient.  It is not usually invoked directly, but is started from
       XEmacs by loading the gnuserv package and evaluating the Lisp form (gnuserv-start).

       gnuclient allows the user to request a running XEmacs process to edit the named	files  or
       directories and/or evaluate lisp forms.	Depending on your environment, TTY, X, GTK, or MS
       Windows frames, as well as batch (frameless) execution of Lisp may be available.  One typ-
       ical  use  for this is with a dialup connection to a machine on which an XEmacs process is
       currently running.

       gnudoit is a shell script frontend to ``gnuclient -batch -eval form''.  Its use is  depre-
       cated. Try to get used to calling gnuclient directly.

       gnuattach no longer exists. Its functionality has been replaced by gnuclient -nw.

OPTIONS
       gnuclient supports as many of the command line options of Emacs as make sense in this con-
       text. In addition it adds a few of its own.
       For backward compatibility, ``long'' options (.e., with doubled hyphen) may  be	specified
       using  a  single hyphen instead of a doubled one.  Similarly, the ``-nw'' option is a his-
       torical artifact: a multiletter option with no double-hyphen version.

       -nw     This option makes gnuclient act as a frontend such that XEmacs can attach  to  the
	       current TTY. XEmacs will then open a new TTY frame.  The effect is similar to hav-
	       ing started a new XEmacs on this TTY with the ``-nw'' option.  It  currently  only
	       works  if  XEmacs is running on the same machine as gnuclient. This is the default
	       if the `DISPLAY' environment variable is not set.

       --display display, -display display
	       If this option is given or the `DISPLAY' environment variable  is  set  then  gnu-
	       client will tell XEmacs to edit files in a frame on the specified X device.

       -q      This  option  informs  gnuclient  to  exit  once connection has been made with the
	       XEmacs process.	Normally gnuclient waits until all of the files  on  the  command
	       line have been finished with (their buffers killed) by the XEmacs process, and all
	       the forms have been evaluated.  Note that this is different  from  XEmacs  itself,
	       where this option means to inhibit loading of the user init file.

       -v      When this option is specified gnuclient will request for the specified files to be
	       viewed instead of edited.

       -l library
	       Tell Emacs to load the specified library.

       -batch  Tell Emacs not to open any frames. Just load libraries and evaluate lisp code.  If
	       no  files  to  execute, functions to call or forms to eval are given using the -l,
	       -f, or -eval options, then forms to eval are read from STDIN.

       -f function,
	       Make Emacs execute the lisp function.

       --eval form, -eval form
	       Make Emacs execute the Lisp form.

       -h hostname
	       Used only with Internet-domain sockets, this option  specifies  the  host  machine
	       which should be running gnuserv. If this option is not specified then the value of
	       the environment variable GNU_HOST is used if set. If no hostname is specified, and
	       the  GNU_HOST  variable	is not set, an Internet connection will not be attempted.
	       N.B.: gnuserv does NOT allow Internet connections unless XAUTH  authentication  is
	       used  or  the  GNU_SECURE variable has been specified and points at a file listing
	       all trusted hosts. (See SECURITY below.)

	       An Internet address (``dotted-quad'') may be  specified	instead  of  a	hostname.
	       IPv6 support is not robust.

	       A hostname of unix can be used to specify that the connection to the server should
	       use a Unix-domain socket (if supported) rather than an Internet-domain socket.

       -p port Used only with Internet-domain sockets, this option  specifies  the  service  port
	       used  to communicate between server and clients.  If this option is not specified,
	       then the value of the environment variable GNU_PORT is used, if set,  otherwise	a
	       service	called ``gnuserv'' is looked up in the services database.  Finally, if no
	       other value can be found for the port, then a default port is used which  is  usu-
	       ally 21490 + uid.
	       Note  that  since gnuserv doesn't allow command-line options, the port for it will
	       have to be specified via one of the alternative methods.

       -r pathname
	       Used only with Internet-domain sockets, the pathname argument  may  be  needed  to
	       inform  XEmacs  how  to	reach  the root directory of a remote machine.	gnuclient
	       prepends this string to each path argument given.  For example, if you were trying
	       to edit a file on a client machine called otter, whose root directory was accessi-
	       ble from the server machine via the path /net/otter, then this argument should  be
	       set  to '/net/otter'.  If this option is omitted, then the value is taken from the
	       environment variable GNU_NODE, if set, or the empty string otherwise.

       [+n] file
	       This is the path of the file to be edited.  If the file is a directory,	then  the
	       directory browsers dired or monkey are usually invoked instead.	The cursor is put
	       at line number 'n' if specified.

SETUP
       gnuserv is included with recent versions of XEmacs;  no	installation  is  required.   The
       server  must be started before clients may attempt to connect.  Start the server by evalu-
       ating the Lisp form (gnuserv-start), or interactively by typing `M-x gnuserv-start'.

CONFIGURATION
       The behavior of this suite of programs can be customized to a  large  extent.   Type  `M-x
       customize-group	 RET  gnuserv  RET'.   More  documentation  can  be  found  in	the  file
       `gnuserv.el'

EXAMPLE
	   gnuclient -q -f mh-smail
	   gnuclient -h cuckoo -r /ange@otter: /tmp/*
	   gnuclient -nw ../src/listproc.c

       More examples and sample wrapper scripts are provided in the etc/gnuserv directory of  the
       XEmacs installation.

SYSV IPC
       SysV  IPC  is  a  build-time option, enabled by defining the symbol SYSV_IPC at the top of
       gnuserv.h.  It is used to communicate between gnuclient and gnuserv.  It  is  incompatible
       with  both Unix-domain and Internet-domain socket communication as described below. A file
       called /tmp/gsrv??? is created as a key for the message queue, and if removed  will  cause
       the communication between server and client to fail until the server is restarted.

UNIX-DOMAIN SOCKETS
       Unix-domain   sockets   are   a	 build-time   option,  enabled	by  defining  the  symbol
       UNIX_DOMAIN_SOCKETS at the top of gnuserv.h.  A Unix-domain socket is used to  communicate
       between	gnuclient and gnuserv.	A file called /tmp/gsrvdir????/gsrv is created for commu-
       nication.  If the symbol USE_TMPDIR is set at the top of gnuserv.h, $TMPDIR, when set,  is
       used  instead  of  /tmp.   If that file is deleted, or TMPDIR has different values for the
       server and the client, communication between server and client will fail.  Only	the  user
       running gnuserv will be able to connect to the socket.

INTERNET-DOMAIN SOCKETS
       Internet-domain	sockets  are  a  build-time option, enabled by defining the symbol INTER-
       NET_DOMAIN_SOCKETS at the top of gnuserv.h.  Internet-domain sockets are used to  communi-
       cate  between  gnuclient and gnuserv.  Both Internet-domain and Unix-domain sockets can be
       used at the same time.  If a hostname is specified via -h or via the GNU_HOST  environment
       variable, gnuclient establish connections using an Internet domain socket. If not, a local
       connection is attempted via either a Unix-domain socket or SYSV IPC.

SECURITY
       Using Internet-domain sockets, a more robust form of security is needed that wasn't neces-
       sary  with either Unix-domain sockets or SysV IPC. Currently, two authentication protocols
       are supported to provide this: MIT-MAGIC-COOKIE-1 (based on the X11 xauth(1) program)  and
       a  simple  host-based  access control mechanism, hereafter called GNUSERV-1. The GNUSERV-1
       protocol is always available.  Support for  MIT-MAGIC-COOKIE-1  is  enabled  (by  defining
       AUTH_MAGIC_COOKIE at the top of gnuserv.h.

       gnuserv,  using GNUSERV-1, performs a limited form of access control at the machine level.
       By default no Internet-domain socket is opened.	If the variable GNU_SECURE can	be  found
       in  gnuserv's  environment, and it names a readable filename, then this file is opened and
       assumed to be a list of hosts, one per line, from which the server  will  allow	requests.
       Connections  from  any  other  host will be rejected. Even the machine on which gnuserv is
       running is not permitted to make connections via the Internet socket unless  its  hostname
       is explicitly specified in this file.  Note that a host may be either a numeric IP address
       or a hostname, and that any user on an approved host may connect to your gnuserv and  exe-
       cute  arbitrary	Lisp (e.g., delete all your files).  If this file contains a lot of host-
       names then the server may take quite a long time to start up.

       When the MIT-MAGIC-COOKIE-1 protocol is enabled, an Internet socket is opened by  default.
       gnuserv will accept a connection from any host, and will wait for a "magic cookie" (essen-
       tially, a password) to be presented by the client.  If  the  client  doesn't  present  the
       cookie,	or if the cookie is wrong, the authentication of the client is considered to have
       failed. At this point. gnuserv falls back to the GNUSERV-1  protocol;  If  the  client  is
       calling from a host listed in the GNU_SECURE file, the connection will be accepted, other-
       wise it will be rejected.

       Using MIT-MAGIC-COOKIE-1 authentication
	   When the gnuserv server is started, it looks for a cookie defined for display  999  on
	   the	machine where it is running. If the cookie is found, it will be stored for use as
	   the authentication cookie. These cookies are defined in an authorization file (usually
	   ~/.Xauthority) that is manipulated by the X11 xauth(1) program. For example, a machine
	   "kali" which runs an emacs that invokes gnuserv should  respond  as	follows  (at  the
	   shell prompt) when set up correctly.

	       kali% xauth list
	       GS65.SP.CS.CMU.EDU:0  MIT-MAGIC-COOKIE-1  11223344
	       KALI.FTM.CS.CMU.EDU:999	MIT-MAGIC-COOKIE-1  1234

	   In the above case, the authorization file defines two cookies. The second one, defined
	   for screen 999 on the server machine, is used for gnuserv authentication.

	   On the client machine's side, the authorization file must contain an  identical  line,
	   specifying  the server's cookie. In other words, on a machine "foobar" which wishes to
	   connect to "kali,"  the `xauth list' output should contain the line:

	       KALI.FTM.CS.CMU.EDU:999	MIT-MAGIC-COOKIE-1  1234

	   For more information on authorization files, take a look at the xauth(1X11) man  page,
	   or  invoke  xauth interactively (without any arguments) and type "help" at the prompt.
	   Remember that  case	in  the  name  of  the	authorization  protocol  (i.e.`MIT-MAGIC-
	   COOKIE-1') is significant!

ENVIRONMENT
       DISPLAY Default X (or GTK) device for display of edit frame.

FILES
       /tmp/gsrv???
	       (SYSV_IPC only)

       /tmp/gsrvdir???/gsrv
	       (unix domain sockets only)

       ~/.xemacs/init.el
	       XEmacs customization file, see xemacs(1).

SEE ALSO
       xauth(1X11), Xsecurity(1X11), gnuserv.el

BUGS
       NULs occurring in result strings don't get passed back to gnudoit properly.

AUTHOR.
       Andy Norman (ange@hplb.hpl.hp.com), based heavily upon etc/emacsclient.c, etc/server.c and
       lisp/server.el from the GNU Emacs 18.52	distribution.	Various  modifications	from  Bob
       Weiner	 (weiner@mot.com),    Darrell	 Kindred   (dkindred@cmu.edu),	 Arup	Mukherjee
       (arup@cmu.edu), Ben Wing (ben@xemacs.org) and Hrvoje Niksic (hniksic@xemacs.org).

4th Berkeley Distribution							       GNUSERV(1)
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