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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

       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, it can be an X
       frame or a TTY frame.  One typical 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
       deprecated. Try to get used to calling gnuclient directly.

       gnuserv is the server program that is set running by XEmacs to  handle  all  incoming  and
       outgoing  requests.  It  is  not  usually  invoked directly, but is started from XEmacs by
       loading the gnuserv package and evaluating the Lisp form (gnuserv-start).

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 Its functionality has been replaced by gnuclient -nw.

OPTIONS

       gnuclient supports as much of the command line options of Emacs as  makes  sense  in  this
       context. In addition it adds a few of its own.
       Options  with  long  names can also be specified using a double hyphen instead of a single
       one.

       -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
               having 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
               gnuclient 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.

       -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
               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.)

               Note  that  an  internet  address may be specified instead of a hostname which can
               speed up connections to the server by  quite  a  bit,  especially  if  the  client
               machine is running YP.

               Note  also  that  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
               usually 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
               accessible  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  packaged standardly with recent versions of XEmacs.  Therefore, you should be
       able to start the server simply by evaluating the XEmacs  Lisp  form  (gnuserv-start),  or
       equivalently by typing `M-x gnuserv-start'.

CONFIGURATION

       The  behavior  of this suite of program is mostly controlled on the lisp side in Emacs and
       its behavior can be customized to a large extent.  Type `M-x customize-group  RET  gnuserv
       RET' for easy access. 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
       Emacs installation.

SYSV IPC

       SysV IPC is used to communicate between gnuclient and gnuserv if the  symbol  SYSV_IPC  is
       defined  at the top of gnuserv.h. This 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

       A Unix-domain socket is used to communicate between gnuclient and gnuserv  if  the  symbol
       UNIX_DOMAIN_SOCKETS   is   defined   at   the   top   of   gnuserv.h.    A   file   called
       /tmp/gsrvdir????/gsrv is created for communication.  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 used to communicate  between  gnuclient  and  gnuserv  if  the
       symbol  INTERNET_DOMAIN_SOCKETS  is  defined at the top of gnuserv.h. 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
       necessary 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, whereas support for MIT-MAGIC-COOKIE-1 may or may
       not have been enabled (via a #define at the top of gnuserv.h) at compile-time.

       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
       execute arbitrary elisp (e.g., delete all your files).  If this file  contains  a  lot  of
       hostnames then the server may take quite a 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"
       (essentially, 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,
       otherwise 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 device to put edit frame.

FILES

       /tmp/gsrv???
               (SYSV_IPC only)

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

       ~/.emacs
               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).