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Xserver.doc
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XSERVER(1) USER COMMANDS XSERVER(1)
NAME
Xserver - X Window System server
SYNOPSIS
X [:displaynumber] [-option ...] [ttyname]
DESCRIPTION
_X is the generic name for the X Window System server. It is
frequently a link or a copy of the appropriate server binary
for driving the most frequently used server on a given
machine.
STARTING THE SERVER
The server is usually started from the X Display Manager
program _x_d_m. This utility is run from the system boot files
and takes care of keeping the server running, prompting for
usernames and passwords, and starting up the user sessions.
It is easily configured for sites that wish to provide nice,
consistent interfaces for novice users (loading convenient
sets of resources, starting up a window manager, clock, and
nice selection of terminal emulator windows).
Installations that run more than one window system will
still need to use the _x_i_n_i_t utility. However, _x_i_n_i_t is to
be considered a tool for building startup scripts and is not
intended for use by end users. Site administrators are
strongly urged to use _x_d_m, or build other interfaces for
novice users.
When the X server starts up, it takes over the display. If
you are running on a workstation whose console is the
display, you cannot log into the console while the server is
running.
NETWORK CONNECTIONS
The X server supports connections made using the following
reliable byte-streams:
_T_C_P/_I_P
The server listens on port 6000+_n, where _n is the
display number.
_U_n_i_x _D_o_m_a_i_n
The X server uses /_t_m_p/._X_1_1-_u_n_i_x/_Xn as the filename for
the socket, where _n is the display number.
_D_E_C_n_e_t
The server responds to connections to object _X$_Xn, where
_n is the display number. This is not supported in all
environments.
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XSERVER(1) USER COMMANDS XSERVER(1)
OPTIONS
All of the X servers accept the following command line
options:
-a _n_u_m_b_e_r
sets pointer acceleration (i.e. the ratio of how
much is reported to how much the user actually moved
the pointer).
-auth _a_u_t_h_o_r_i_z_a_t_i_o_n-_f_i_l_e
Specifies a file which contains a collection of
authorization records used to authenticate access.
See also the _x_d_m and _X_s_e_c_u_r_i_t_y manual pages.
bc disables certain kinds of error checking, for bug
compatibility with previous releases (e.g., to work
around bugs in R2 and R3 xterms and toolkits).
Deprecated.
-bs disables backing store support on all screens.
-c turns off key-click.
c _v_o_l_u_m_e
sets key-click volume (allowable range: 0-100).
-cc _c_l_a_s_s
sets the visual class for the root window of color
screens. The class numbers are as specified in the
X protocol. Not obeyed by all servers.
-co _f_i_l_e_n_a_m_e
sets name of RGB color database.
-dpi _r_e_s_o_l_u_t_i_o_n
sets the resolution of the screen, in dots per inch.
To be used when the server cannot determine the
screen size from the hardware.
-f _v_o_l_u_m_e
sets feep (bell) volume (allowable range: 0-100).
-fc _c_u_r_s_o_r_F_o_n_t
sets default cursor font.
-fn _f_o_n_t
sets the default font.
-fp _f_o_n_t_P_a_t_h
sets the search path for fonts. This path is a
comma separated list of directories which the X
server searches for font databases.
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XSERVER(1) USER COMMANDS XSERVER(1)
-help prints a usage message.
-I causes all remaining command line arguments to be
ignored.
-ld _k_i_l_o_b_y_t_e_s
sets the data space limit of the server to the
specified number of kilobytes. A value of zero
makes the data size as large as possible. The
default value of -1 leaves the data space limit
unchanged. This option is not available in all
operating systems.
-lf _f_i_l_e_s
sets the number-of-open-files limit of the server to
the specified number. A value is zero makes the
limit as large as possible. The default value of -1
leaves the limit unchanged. This option is not
available in all operating systems.
-ls _k_i_l_o_b_y_t_e_s
sets the stack space limit of the server to the
specified number of kilobytes. A value of zero
makes the stack size as large as possible. The
default value of -1 leaves the stack space limit
unchanged. This option is not available in all
operating systems.
-logo turns on the X Window System logo display in the
screen-saver. There is currently no way to change
this from a client.
nologo turns off the X Window System logo display in the
screen-saver. There is currently no way to change
this from a client.
-p _m_i_n_u_t_e_s
sets screen-saver pattern cycle time in minutes.
-r turns off auto-repeat.
r turns on auto-repeat.
-s _m_i_n_u_t_e_s
sets screen-saver timeout time in minutes.
-su disables save under support on all screens.
-t _n_u_m_b_e_r
sets pointer acceleration threshold in pixels (i.e.
after how many pixels pointer acceleration should
take effect).
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XSERVER(1) USER COMMANDS XSERVER(1)
-to _s_e_c_o_n_d_s
sets default connection timeout in seconds.
tty_x_x ignored, for servers started the ancient way (from
init).
v sets video-off screen-saver preference.
-v sets video-on screen-saver preference.
-wm forces the default backing-store of all windows to
be WhenMapped; a cheap trick way of getting
backing-store to apply to all windows.
-x _e_x_t_e_n_s_i_o_n
loads the specified extension at init. Not sup-
ported in most implementations.
You can also have the X server connect to _x_d_m using XDMCP.
Although this is not typically useful as it does not allow
_x_d_m to manage the server process, it can be used to debug
XDMCP implementations, and serves as a sample implementation
of the server side of XDMCP. For more information on this
protocol, see the _X _D_i_s_p_l_a_y _M_a_n_a_g_e_r _C_o_n_t_r_o_l _P_r_o_t_o_c_o_l specif-
ication. The following options control the behavior of
XDMCP.
-query _h_o_s_t-_n_a_m_e
Enable XDMCP and send Query packets to the specified
host.
-broadcast
Enable XDMCP and broadcast BroadcastQuery packets to
the network. The first responding display manager
will be chosen for the session.
-indirect _h_o_s_t-_n_a_m_e
Enable XDMCP and send IndirectQuery packets to the
specified host.
-port _p_o_r_t-_n_u_m
Use an alternate port number for XDMCP packets.
Must be specified before any -query, -broadcast or
-indirect options.
-once Normally, the server keeps starting sessions, one
after the other. This option makes the server exit
after the first session is over.
-class _d_i_s_p_l_a_y-_c_l_a_s_s
XDMCP has an additional display qualifier used in
resource lookup for display-specific options. This
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XSERVER(1) USER COMMANDS XSERVER(1)
option sets that value, by default it is "MIT-
Unspecified" (not a very useful value).
-cookie _x_d_m-_a_u_t_h-_b_i_t_s
When testing XDM-AUTHENTICATION-1, a private key is
shared between the server and the manager. This
option sets the value of that private data (not that
it is very private, being on the command line!).
-displayID _d_i_s_p_l_a_y-_i_d
Yet another XDMCP specific value, this one allows
the display manager to identify each display so that
it can locate the shared key.
Many servers also have device-specific command line options.
See the manual pages for the individual servers for more
details.
SECURITY
The X server implements a simplistic authorization protocol,
MIT-MAGIC-COOKIE-1 which uses data private to authorized
clients and the server. This is a rather trivial scheme; if
the client passes authorization data which is the same as
the server has, it is allowed access. This scheme is worse
than the host-based access control mechanisms in environ-
ments with unsecure networks as it allows any host to con-
nect, given that it has discovered the private key. But in
many environments, this level of security is better than the
host-based scheme as it allows access control per-user
instead of per-host.
In addition, the server provides support for a DES-based
authorization scheme, XDM-AUTHORIZATION-1, which is more
secure (given a secure key distribution mechanism). This
authorization scheme can be used in conjunction with XDMCP's
authentication scheme (XDM-AUTHENTICATION-1) or in isola-
tion.
The authorization data is passed to the server in a private
file named with the -auth command line option. Each time
the server is about to accept the first connection after a
reset (or when the server is starting), it reads this file.
If this file contains any authorization records, the local
host is not automatically allowed access to the server, and
only clients which send one of the authorization records
contained in the file in the connection setup information
will be allowed access. See the _X_a_u manual page for a
description of the binary format of this file. Maintenance
of this file, and distribution of its contents to remote
sites for use there is left as an exercise for the reader.
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XSERVER(1) USER COMMANDS XSERVER(1)
The server also provides support for SUN-DES-1, using Sun's
Secure RPC. It involves encrypting data with the X server's
public key. See the _X_s_e_c_u_r_i_t_y manual page for more informa-
tion.
The X server also uses a host-based access control list for
deciding whether or not to accept connections from clients
on a particular machine. If no other authorization mechan-
ism is being used, this list initially consists of the host
on which the server is running as well as any machines
listed in the file /_e_t_c/_Xn._h_o_s_t_s, where n is the display
number of the server. Each line of the file should contain
either an Internet hostname (e.g. expo.lcs.mit.edu) or a
DECnet hostname in double colon format (e.g. hydra::).
There should be no leading or trailing spaces on any lines.
For example:
joesworkstation
corporate.company.com
star::
bigcpu::
Users can add or remove hosts from this list and enable or
disable access control using the _x_h_o_s_t command from the same
machine as the server.
The X protocol intrinsically does not have any notion of
window operation permissions or place any restrictions on
what a client can do; if a program can connect to a display,
it has full run of the screen. Sites that have better
authentication and authorization systems (such as Kerberos)
might wish to make use of the hooks in the libraries and the
server to provide additional security models.
SIGNALS
The X server attaches special meaning to the following sig-
nals:
_S_I_G_H_U_P This signal causes the server to close all existing
connections, free all resources, and restore all
defaults. It is sent by the display manager when-
ever the main user's main application (usually an
_x_t_e_r_m or window manager) exits to force the server
to clean up and prepare for the next user.
_S_I_G_T_E_R_M This signal causes the server to exit cleanly.
_S_I_G_U_S_R_1 This signal is used quite differently from either of
the above. When the server starts, it checks to see
if it has inherited SIGUSR1 as SIG_IGN instead of
the usual SIG_DFL. In this case, the server sends a
SIGUSR1 to its parent process after it has set up
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XSERVER(1) USER COMMANDS XSERVER(1)
the various connection schemes. _X_d_m uses this
feature to recognize when connecting to the server
is possible.
FONTS
Fonts are usually stored as individual files in directories.
The X server can obtain fonts from directories and/or from
font servers. The list of directories and font servers the
X server uses when trying to open a font is controlled by
the _f_o_n_t _p_a_t_h. Although most sites will choose to have the
X server start up with the appropriate font path (using the
-_f_p option mentioned above), it can be overridden using the
_x_s_e_t program.
The default font path for the X server contains four direc-
tories:
/_u_s_r/_l_i_b/_X_1_1/_f_o_n_t_s/_m_i_s_c
This directory contains many miscellaneous bitmap
fonts that are useful on all systems. It contains a
family of fixed-width fonts, a family of fixed-width
fonts from Dale Schumacher, several Kana fonts from
Sony Corporation, two JIS Kanji fonts, two Hangul
fonts from Daewoo Electronics, two Hebrew fonts from
Joseph Friedman, the standard cursor font, two cur-
sor fonts from Digital Equipment Corporation, and
cursor and glyph fonts from Sun Microsystems. It
also has various font name aliases for the fonts,
including fixed and variable.
/_u_s_r/_l_i_b/_X_1_1/_f_o_n_t_s/_S_p_e_e_d_o
This directory contains outline fonts for
Bitstream's Speedo rasterizer. A single font face,
in normal, bold, italic, and bold italic, is pro-
vided, contributed by Bitstream, Inc.
/_u_s_r/_l_i_b/_X_1_1/_f_o_n_t_s/_7_5_d_p_i
This directory contains bitmap fonts contributed by
Adobe Systems, Inc., Digital Equipment Corporation,
Bitstream, Inc., Bigelow and Holmes, and Sun
Microsystems, Inc. for 75 dots per inch displays.
An integrated selection of sizes, styles, and
weights are provided for each family.
/_u_s_r/_l_i_b/_X_1_1/_f_o_n_t_s/_1_0_0_d_p_i
This directory contains 100 dots per inch versions
of some of the fonts in the _7_5_d_p_i directory.
Font databases are created by running the _m_k_f_o_n_t_d_i_r program
in the directory containing the compiled versions of the
fonts (the ._p_c_f files). Whenever fonts are added to a
directory, _m_k_f_o_n_t_d_i_r should be rerun so that the server can
X Version 11 Last change: Release 5 7
XSERVER(1) USER COMMANDS XSERVER(1)
find the new fonts. If _m_k_f_o_n_t_d_i_r is not run, the server
will not be able to find any fonts in the directory.
DIAGNOSTICS
Too numerous to list them all. If run from _i_n_i_t(_8), errors
are typically logged in the file /_u_s_r/_a_d_m/_X*_m_s_g_s,
FILES
/etc/X*.hosts Initial access control list
/usr/lib/X11/fonts/100dpi
/usr/lib/X11/fonts/misc, /usr/lib/X11/fonts/75dpi,
Bitmap font directories
/usr/lib/X11/fonts/Speedo Outline font directories
/usr/lib/X11/fonts/PEX PEX font directories
/usr/lib/X11/rgb.txt Color database
/tmp/.X11-unix/X* Unix domain socket
/usr/adm/X*msgs Error log file
SEE ALSO
X(1), bdftopcf(1), mkfontdir(1), fs(1), xauth(1), xdm(1),
xhost(1), xinit(1), xset(1), xsetroot(1), xterm(1), Xdec(1),
Xibm(1), XmacII(1), Xmips(1), Xqdss(1), Xqvss(1), Xsun(1),
Xtek(1), X386(1) _X _W_i_n_d_o_w _S_y_s_t_e_m _P_r_o_t_o_c_o_l, _D_e_f_i_n_i_t_i_o_n _o_f _t_h_e
_P_o_r_t_i_n_g _L_a_y_e_r _f_o_r _t_h_e _X _v_1_1 _S_a_m_p_l_e _S_e_r_v_e_r, _S_t_r_a_t_e_g_i_e_s _f_o_r
_P_o_r_t_i_n_g _t_h_e _X _v_1_1 _S_a_m_p_l_e _S_e_r_v_e_r, _G_o_d_z_i_l_l_a'_s _G_u_i_d_e _t_o _P_o_r_t_i_n_g
_t_h_e _X _V_1_1 _S_a_m_p_l_e _S_e_r_v_e_r
BUGS
The option syntax is inconsistent with itself and _x_s_e_t(_1).
The acceleration option should take a numerator and a denom-
inator like the protocol.
If _X dies before its clients, new clients won't be able to
connect until all existing connections have their TCP
TIME_WAIT timers expire.
The color database is missing a large number of colors.
COPYRIGHT
Copyright 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991
Massachusetts Institute of Technology.
See _X(_1) for a full statement of rights and permissions.
AUTHORS
The sample server was originally written by Susan
X Version 11 Last change: Release 5 8
XSERVER(1) USER COMMANDS XSERVER(1)
Angebranndt, Raymond Drewry, Philip Karlton, and Todd New-
man, from Digital Equipment Corporation, with support from a
large cast. It has since been extensively rewritten by
Keith Packard and Bob Scheifler, from MIT.
X Version 11 Last change: Release 5 9