.\" $XFree86: xc/programs/xfs/xfs.man,v 3.15 2001/04/18 16:13:22 dawes Exp $
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.\" Copyright 1991 Network Computing Devices
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.\" Permission to use, copy, modify, distribute, and sell this software and
.\" its documentation for any purpose is hereby granted without fee, provided
.\" that the above copyright notice appear in all copies and that both that
.\" copyright notice and this permission notice appear in supporting
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.\" $Xorg: xfs.man,v 1.4 2001/02/09 02:05:42 xorgcvs Exp $
.TH xfs __appmansuffix__ __xorgversion__
.SH NAME
xfs \- X font server
.SH SYNOPSIS
.B xfs
[
.BI "\-config " configuration_file
]
[
.B \-daemon
]
[
.B \-droppriv
]
[
.BI "\-ls " listen_socket
]
[
.B \-nodaemon
]
[
.BI "\-port " tcp_port
]
[
.BI "\-user " username
]
.SH DESCRIPTION
.B xfs
is the X Window System font server.
It supplies fonts to X Window System display servers.
The server is usually run by a system administrator, and started via
.BR init (__adminmansuffix__).
Users may also wish to start private font servers for specific sets of
fonts.
.PP
To connect to a font server, see the documentation for your X server; it
likely supports the syntax documented in the \(lqFONT SERVER NAMES\(rq
section of
.BR X (__miscmansuffix__).
.SH OPTIONS
.TP
.BI "\-config " configuration_file
specifies the configuration file
.B xfs
will use.
If this parameter is not specified, xfs will read its configuration from
__configfiledesc__ \fI__configfilepath__\fR.
.TP
.B \-daemon
instructs
.B xfs
to fork and go into the background automatically at startup.
If this option is not specified,
.B xfs
will run as a regular process (unless it was built to daemonize by
default).
When running as a daemon,
.B xfs
will attempt to create a file in which it stores its process ID, and will
delete that file upon exit; 
.TP
.B \-droppriv
instructs
.B xfs
to attempt to run as user and group
.I xfs
(unless the
.B \-user
option is used).
This has been implemented for security reasons, as
.B xfs
may have undiscovered buffer overflows or other paths for possible exploit,
both local and remote.
When using this option, you may also wish to specify \(oqno\-listen =
tcp\(cq in the config file, which ensures that
.B xfs
will not to use a TCP port at all.
By default,
.B xfs
runs with the user and group IDs of the user who invoked it.
.TP
.BI "\-ls " listen_socket
specifies a file descriptor which is already set up to be used as the
listen socket.
This option is only intended to be used by the font server itself when
automatically spawning another copy of itself to handle additional
connections.
.TP
.B \-nodaemon
instructs
.B xfs
not to daemonize (fork and detach from its controlling terminal).
This option only has an effect if
.B xfs
is built to daemonize by default, which is not the stock configuration.
.TP
.BI "\-port " tcp_port
specifies the TCP port number on which the server will listen for
connections.
The default port number is 7100.
This option is ignored if
.B xfs
is configured to not listen to TCP transports at all (see \(lqConfiguration
File Format\(rq below).
.TP
.BI "\-user " username
instructs
.B xfs
to run as the user
.IR username.
See
.B \-droppriv
for why this may be desired.
By default,
.B xfs
runs with the user and group IDs of the user who invoked it.
.SH "INPUT FILES"
.B xfs
reads and serves any font file format recognized by the X server itself.
It locates font files through the specification of a
.IR catalogue ,
which is declared in
.BR xfs 's
configuration file.
.SS "Configuration File Format"
.B xfs
reads its configuration from a text file (see the
.B \-config
option in the \(lqOPTIONS\(rq section above).
The configuration language is a list of keyword and value pairs.
Each keyword is followed by an equals sign (\(oq=\(cq) and then the desired
value.
.PP
Recognized keywords include:
.TP
.BR alternate\-servers " (list of \fIstring\fPs)"
lists alternate servers for this font server.
See the \(lqFONT SERVER NAMES\(rq section of
.BR X (__miscmansuffix__)
for the syntax of the string.
.\" .TP
.\" .BR cache\-size " (\fIcardinal\fP)"
.\" determines the size (in bytes) of the font server cache.
.TP
.BR catalogue " (list of \fIstring\fPs)"
declares as ordered list of font path element names from which fonts will
be served.
The current implementation only supports a single catalogue ("all")
containing all of the specified fonts. A special directory with
symlinks to font paths can be specified using a catalogue:<dir>
entry. See the CATALOGUE DIR section below for details.
.TP
.BR client\-limit " (\fIcardinal\fP)"
determines the number of clients this font server will support before
refusing service.
This is useful for tuning the load on each individual font server.
.TP
.BR clone\-self " (\fIboolean\fP)"
indicates whether this font server should attempt to clone itself when the
number of connected clients reaches the
.BR client\-limit .
.TP
.BR default\-point\-size " (\fIcardinal\fP)"
The default pointsize (in decipoints) for font requests that don't specify
a point size.
The default is 120.
.TP
.BR default\-resolutions " (list of \fIresolution\fPs)"
indicates the resolutions the server supports by default.
This information may be used as a hint for pre-rendering, and substituted
into requests for scaled fonts which do not specify a resolution.
A
.I resolution
is a comma-separated pair of horizontal and vertical resolutions in pixels
per inch.
Multiple resolutions are separated by commas.
.TP
.BR deferglyphs " (\fIstring\fP)"
sets the mode for delayed fetching and caching of glyphs.
.I string
should be one of \(oqnone\(cq, meaning glyphs deferment is disabled,
\(oqall\(cq, meaning it is enabled for all fonts, and \(oq16\(cq, meaning
it is enabled only for 16-bit fonts.
.TP
.BR error\-file " (\fIstring\fP)"
indicates the filename of the error file.
All warnings and errors will be logged here, unless
.B use\-syslog
is set to a true value (see below).
.TP
.BR no\-listen " (\fItrans-type\fP)"
disables the specified transport type.
For example, TCP/IP connections can be disabled with \(oqno\-listen =
tcp\(cq.
.TP
.BR port " (\fIcardinal\fP)"
indicates the TCP port on which the server will listen for connections.
.\" .TP
.\" .BR trusted-clients " (list of \fIstring\fPs)"
.\" identifies the clients the font server will talk to.
.\" Others will be refused for the initial connection.
.\" An empty list means the server will talk to any client.
.TP
.BR use\-syslog " (\fIboolean\fP)"
determines whether errors and diagnostics should be reported via
.BR syslog (__libmansuffix__)
(on supported systems) instead of being written to the
.B error\-file
(see above).
.SH "CATALOGUE DIR"
You can specify a special kind of font path in the form \fBcatalogue:<dir>\fR.
The directory specified after the catalogue: prefix will be scanned for symlinks
and each symlink destination will be added as a local fontfile FPE.
.PP
The symlink can be suffixed by attributes such as '\fBunscaled\fR', which
will be passed through to the underlying fontfile FPE. The only exception is
the newly introduced '\fBpri\fR' attribute, which will be used for ordering
the font paths specified by the symlinks.

An example configuration:

.nf
    75dpi:unscaled:pri=20 \-> /usr/share/X11/fonts/75dpi
    ghostscript:pri=60 \-> /usr/share/fonts/default/ghostscript
    misc:unscaled:pri=10 \-> /usr/share/X11/fonts/misc
    type1:pri=40 \-> /usr/share/X11/fonts/Type1
    type1:pri=50 \-> /usr/share/fonts/default/Type1
.fi

This will add /usr/share/X11/fonts/misc as the first FPE with the attribute
'unscaled', second FPE will be /usr/share/X11/fonts/75dpi, also with
the attribute unscaled etc. This is functionally equivalent to setting
the following font path:

.nf
    /usr/share/X11/fonts/misc:unscaled,
    /usr/share/X11/fonts/75dpi:unscaled,
    /usr/share/X11/fonts/Type1,
    /usr/share/fonts/default/Type1,
    /usr/share/fonts/default/ghostscript
.fi
.SS "Example Configuration File"
.nf
XCOMM
XCOMM sample font server configuration file
XCOMM

XCOMM allow a max of 10 clients to connect to this font server.
client\-limit = 10

XCOMM When a font server reaches the above limit, start up a new one.
clone\-self = on

XCOMM Identify alternate font servers for clients to use.
alternate\-servers = hansen:7101,hansen:7102

XCOMM Look for fonts in the following directories.  The first is a set of
XCOMM TrueType outlines, the second is a set of misc bitmaps (such as terminal
XCOMM and cursor fonts), and the last is a set of 100dpi bitmaps.
XCOMM
catalogue = /usr/X11R6/lib/X11/fonts/TTF,
            /usr/X11R6/lib/X11/fonts/misc,
            /usr/X11R6/lib/X11/fonts/100dpi/

XCOMM in 12 points, decipoints
default\-point\-size = 120

XCOMM 100 x 100 and 75 x 75
default\-resolutions = 100,100,75,75

XCOMM Specify our log filename.
error\-file = /var/log/xfs.log

XCOMM Direct diagnostics to our own log file instead of using syslog.
use\-syslog = off
.fi
.SH "OUTPUT FILES"
When operating in daemon mode,
.B xfs
sends diagnostic messages (errors and warnings) to the system log via the
.B syslog
C library function by default.
However, these messages can be sent to an alternate location via the
.B error\-file
and
.B use\-syslog
configuration variables; see \(lqConfiguration File Format\(rq, above.
.SH "ASYNCHRONOUS EVENTS"
.B xfs
handles the following signals specially:
.TP
.I SIGTERM
causes the font server to exit cleanly.
.TP
.I SIGUSR1
causes
.B xfs
to re-read its configuration file.
.TP
.I SIGUSR2
causes
.B xfs
to flush any cached data it may have.
.TP
.I SIGHUP
causes
.B xfs
to reset, closing all active connections and re-reading the configuration
file.
.SH BUGS
Multiple catalogues should be supported.
.SH "FUTURE DIRECTIONS"
Significant further development of
.B xfs
is unlikely.
One of the original motivations behind it was the single-threaded nature of
the X server \(em a user's X session could seem to \(oqfreeze up\(cq while
the X server took a moment to rasterize a font.
This problem with the X server, which remains single-threaded in all
popular implementations to this day, has been mitigated on two fronts:
machines have gotten much faster, and client-side font rendering
(particularly via the Xft library) is the norm in contemporary software.
.SH AUTHORS
Dave Lemke, Network Computing Devices, Inc
.br
Keith Packard, Massachusetts Institute of Technology
.SH "SEE ALSO"
.BR X (__miscmansuffix__),
.BR xfsinfo (__appmansuffix__),
.BR fslsfonts (__appmansuffix__),
.BR init (__adminmansuffix__),
.BR syslog (__libmansuffix__),
.IR "The X Font Service Protocol" ,
.I Font Server Implementation Overview