Manual Pages for UNIX Darwin command on man gnuattach

GNUSERV(1) GNUSERV(1)

NAME

gnuserv, gnuclient - Server and Clients for Emacs

SYNOPSIS

ggnnuucclliieenntt [-nw] [-display display] [-q] [-v] [-l library] [-batch] [-f

function] [-eval form] [-h hostname] [-p port] [-r remote-pathname]

[[+line] file] ...

ggnnuuddooiitt [[-qq]] form

ggnnuusseerrvv ggnnuuaattttaacchh Removed as of gnuserv 3.x

DESCRIPTION

gnuclient allows the user to request a running emacs 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 emacs 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 emacs to handle all incoming and outgoing requests. It is not usually invoked directly, but is started from emacs by loading the gnuserv package and evaluating

the Lisp form (gnuserv-start).

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 Its functionality has been replaced by gnu-

client -nw.

OOPPTTIIOONNSS 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.

-nnww This option makes gnuclient act as a frontend such that emacs

can attach to the current TTY. emacs will then open a new TTY frame. The effect is similar to having started a new emacs on

this TTY with the ``-nw'' option. It currently only works if

emacs is running on the same machine as gnuclient. This is the default if the `DISPLAY' environment variable is not set.

-ddiissppllaayy display, --ddiissppllaayy display

If this option is given or the `DISPLAY' environment variable is set then gnuclient will tell emacs to edit files in a frame on the specified X device.

-qq This option informs gnuclient to exit once connection has been

made with the emacs process. Normally gnuclient waits until all of the files on the command line have been finished with (their buffers killed) by the emacs process, and all the forms have been evaluated.

-vv When this option is specified gnuclient will request for the

specified files to be viewed instead of edited.

-ll library

Tell Emacs to load the specified library.

-bbaattcchh 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 -ll, -ff, or -eevvaall options,

then forms to eval are read from STDIN.

-ff function,

Make Emacs execute the lisp function.

-eevvaall form

Make Emacs execute the lisp form.

-hh 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 vari-

able GNUHOST is used if set. If no hostname is specified, and the GNUHOST variable is not set, an internet connection will

not be attempted. N.B.: gnuserv does NOT allow internet connec-

tions unless XAUTH authentication is used or the GNUSECURE 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 uunniixx 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.

-pp 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 GNUPORT is used, if set, otherwise a

service called ``gnuserv'' is looked up in the services data-

base. 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 alterna-

tive methods.

-rr pathname

Used only with Internet-domain sockets, the pathname argument

may be needed to inform emacs 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 GNUNODE, if set, or the empty string otherwise. [[++nn]] ffiillee This is the path of the file to be edited. If the file is a

directory, then the directory browsers dired or monkey are usu-

ally invoked instead. The cursor is put at line number 'n' if specified. SSEETTUUPP gnuserv is packaged with emacs on Mac OS X. Therefore, you should be able to start the server simply by evaluating the emacs lisp form

(gnuserv-start), or equivalently by typing `M-x gnuserv-start'.

CCOONNFFIIGGUURRAATTIIOONN 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 docu-

mentation can be found in the file `gnuserv.el' EEXXAAMMPPLLEE

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. SSYYSSVV IIPPCC SysV IPC is used to communicate between gnuclient and gnuserv if the

symbol SYSVIPC is defined at the top of gnuserv.h. This is incompati-

ble 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.

UUNNIIXX-DDOOMMAAIINN SSOOCCKKEETTSS

A Unix-domain socket is used to communicate between gnuclient and

gnuserv if the symbol UNIXDOMAINSOCKETS is defined at the top of

gnuserv.h. A file called /tmp/gsrvdir????/gsrv is created for communi-

cation and if deleted will cause communication between server and client to fail. Only the user running gnuserv will be able to connect to the socket.

IINNTTEERRNNEETT-DDOOMMAAIINN SSOOCCKKEETTSS

Internet-domain sockets are used to communicate between gnuclient and

gnuserv if the symbol INTERNETDOMAINSOCKETS 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 GNUHOST

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.

SSEECCUURRIITTYY

Using Internet-domain sockets, a more robust form of security is needed

that wasn't necessary with either Unix-domain sockets or SysV IPC. Cur-

rently, 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 GNUSECURE 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 host-

name, 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 pre-

sented 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 proto-

col; If the client is calling from a host listed in the GNUSECURE 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 ~/.Xau-

thority) that is manipulated by the X11 xauth(1) program. For exam-

ple, a machine "kali" which runs an emacs that invokes gnuserv

should respond as follows (at the shell prompt) when set up cor-

rectly.

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 DDIISSPPLLAAYY Default X device to put edit frame. FILES //ttmmpp//ggssrrvv?????? (SYSVIPC only) //ttmmpp//ggssrrvvddiirr??????//ggssrrvv (unix domain sockets only) ~~//..eemmaaccss emacs customization file, see emacs(1).

BUGS

NULs occurring in result strings don't get passed back to gnudoit prop-

erly.

The -nnww flag does not work, due to lack of necessary functionality in

emacs. AUTHOR.

Andy Norman (ange@hplb.hpl.hp.com), based heavily upon etc/emac-

sclient.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)