lyskomd.texi

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@c $Id: lyskomd.texi,v 1.75 2003/08/20 13:45:08 ceder Exp $
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@settitle lyskomd @value{VERSION} Reference Manual
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This is the reference manual for the lyskomd LysKOM server version
@value{VERSION}.

Copyright @copyright{} 1995-2002 Lysator ACS.

Permission is granted to make and distribute verbatim copies of this
specification provided the copyright notice and this permission notice
are preserved on all copies.
@end ifinfo

@dircategory LysKOM
@direntry
* lyskomd: (lyskomd).                lyskomd reference manual.
@end direntry

@titlepage
@sp 10
@title lyskomd Reference Manual
@sp 2
@subtitle Server version @value{VERSION}
@sp 2
@author by the lyskomd developers

@page
@vskip 0pt plus 1filll
Copyright @copyright{} 1995-2002 Lysator ACS

Permission is granted to make and distribute verbatim copies of this document
provided the copyright notice and this permission notice are preserved on all
copies.

Modified versions of this document may be redistributed with the added
condition that all modifications not cleared with the LysKOM development group
are clearly marked and that the entire modified work be redistributed under the
same conditions as the original.

Permission is granted to copy and distribute translations of this manual into
another language under the same conditions as for modified versions.

@end titlepage

@ifinfo
@node Top
@top lyskomd

lyskomd is a server for the LysKOM conferencing system. This info file
documents version @value{VERSION} of lyskomd.

@menu
* Copying::                     lyskomd is free software.
* Overview::                    Overview of LysKOM.
* Installation::                How to install lyskomd.
* Configuration::               How to configure lyskomd.
* Running lyskomd::             How to run lyskomd.
* Invoking updateLysKOM::       How to run updateLysKOM.
* Invoking komrunning::         How to run komrunning.
* Administration::              Administering a LysKOM server.
* Bugs::                        Known bugs in lyskomd.
* DBCK Reference::              Checking and repairing the database.
* splitkomdb::                  How to backup the database.
* Hacking::                     Notes for server developers.
* lyskomd Database Specification::  
@end menu

@end ifinfo

@node Copying
@chapter Copying

lyskomd is free software. It is distributed under the Gnu General Public
License version 2. The file COPYING in the top level of the distribution
contains the text of the license.


@node Overview
@chapter Overview

LysKOM is a conferencing system@footnote{Or in modern terms, enabling
technology for Computer-Supported Cooperative Work (CSCW).}. Similar
systems were QZ-KOM and PortaCOM@footnote{Also known as ``PottaKOM'' and
``BortaKOM''.}. The LysKOM system is copyrighted by Lysator Academic
Computing Society and distributed under conditions of the GNU General Public
License version 2. LysKOM and its documentation is provided ``as is'' without
warranty of any kind.

This reference manual documents version @value{VERSION} of the lyskomd
LysKOM server. The lyskomd server is the work of several people. The main
contributors have been
Per Cederqvist @email{ceder@@lysator.liu.se},
Inge Wallin @email{inge@@lysator.liu.se},
Thomas Bellman @email{bellman@@lysator.liu.se},
David Byers @email{byers@@lysator.liu.se} and
Peter Eriksson @email{pen@@lysator.liu.se}.


@section History

In 1990, Per Cederqvist @email{ceder@@lysator.liu.se} and Peter Eriksson
@email{pen@@lysator.liu.se} and a few other persons started to write the
server. It was operational in the summer of 1990, even though the
members of Lysator discovered a thing called MUD. We started using RCS
on 20 May 1991. The first release was made on 16 Sept 1991. Around that
time we switched from RCS to CVS to handle our source code.



@node Installation
@chapter Installation

Instructions for compiling and installing lyskomd are in the files
@file{README} and @file{INSTALL}, located in the top level of the
lyskomd distribution.  Installation should be straightforward on most
platforms.


@node Configuration
@chapter Configuration

There are two configuration files for lyskomd. One defines the server
options and the other defines aux-item types @ref{(protocol-a)The
Aux-Item List,The Aux-Item List}.

@menu
* Server Configuration File::   The server configuration file.
* Aux-Item Definition File::    The aux-item definition file.
@end menu


@node Server Configuration File
@section Server Configuration File

The server reads its configuration from a configuration file. The
default configuration file is @file{/usr/lyskom/etc/config}. The
location of the configuration file can be changed at run-time by
supplying an argument to lyskomd.

The configuration file is line oriented. Each line consists of a
parameter name followed by a colon, and the value of the parameter.
Empty lines and lines whose first non-blank character is a @samp{#} are
ignored.

@menu
* Parameter Types::             Types of configuration parameters.
* Parameters::                  Valid configuration parameters.
@end menu

@node Parameter Types
@subsection Parameter Types

Every parameter has a type. The standard types are:

@table @code
@item bool
The parameter can be true or false. Legal values are @code{on},
@code{true}, @code{yes} and @code{1} for true and @code{off},
@code{false}, @code{no} and @code{0} for false.

@item locale-name
The parameter is a locale name. The value must be a legal locale name of
the system where lyskomd is running.

@item path
The parameter is a path name. The value must be a legal path on the
system where lyskomd is running. Most paths you can specify can be
either absolute paths (if they begin with a @samp{/}) or paths relative
to the installation prefix which is specified at compile time and can
be overridden by the @code{Prefix:} parameter in the configuration file.

@item portname
The parameter is a TCP/IP port. It can be a symbolic port name
(traditionally looked up in @file{/etc/services}) or a port number.

@item int
The parameter is a number of some sort. It can be a conference number,
text number or perhaps something else.

@item double
The parameter is a floating point number.  Any syntax that the C
function @code{strtod} accepts is OK.  Examples of truly portable
values: @samp{1} or @samp{1.3}.

@item timeval
The parameter is a time period.  It consists of a floating point
number (in the same format as for parameters of type @code{double}),
optionally followed by optional whitespace and a suffix.  If no suffix
is specified, it defaults to the suffix mentioned in the description
of the parameter.

Valid suffixes includes:

@itemize
@item seconds
@item second
@item sec
@item s
@item minutes
@item minute
@item min
@item hours
@item hour
@item h
@item days
@item day
@item d
@item milliseconds
@item millisecond
@item m
@item microseconds
@item microsecond
@item u
@end itemize

@end table

A few parameters have ad-hoc types, that are used for a single
parameter.  They are documented in the description of that parameter.

@node Parameters
@subsection Parameters

@table @code

@item Max conferences: @var{int}
The maximum number of conferences possible in the server. This number
must be larger than the number of conferences in the database. This
parameter is required. There is no default.

@item Max texts: @var{int}
The maximum number of texts possible in the server. This number
must be larger than the number of texts in the database. This
parameter is required. There is no default.

@item Locale: @var{string}
Use @var{string} as the locale to run in. This parameter is only
available om systems which support the @code{setlocale} call. If this
parameter is not set, no call to @code{setlocale} will be made. The
default is unset.

@item Force ISO 8859-1: @var{bool}
This option is provided for those with dysfunctional computers that
cannot handle @code{setlocale} properly. If this is set, lyskomd will
handle texts according to the ISO 8859-1 (latin1) alphabet. Default
is off.

@item Prefix: @var{path}
Specify the installation prefix.  All relative filenames that the
server uses are interpreted relative to this directory.  The default
value of this parameter is set at compile time.  The default is
@file{/usr/lyskom}, but it can be changed by the @samp{--prefix}
argument of @samp{configure} at compile time.

@item Send async: @var{bool}
Do not send any non-requested messages. This disables the sending of
messages about events in the server to all connections. Use of this
parameter is not recommended. Default is on.

@item Client host: @var{hostname}
Specify which IP number the server should use when listening for new
clients.  @var{hostname} may be a FQDN (such as
@samp{kom.lysator.liu.se}) or an IP number (such as @samp{10.0.0.1}).
Default is to bind @code{INADDR_ANY}, which means that the server will
listen to all IP numbers of the computer it is running on.

@item Client port: @var{portname}
Listen for new clients on port @var{portname}. The default is 4894, which
is what all clients expect. Do not change this parameter without really
good reason.

@item Presentation of conferences: @var{int}
The number of the conference where presentations should be sent.
Defaults to 1. This option is ignored in lyskomd 1.9 and later. Set this
using dbck or the @ref{(protocol-a)set-info,set-info}.


@item Presentation of persons: @var{int}
The number of the conference where presentations should be sent.
Defaults to 2. This option is ignored in lyskomd 1.9 and later. Set this
using dbck or the @ref{(protocol-a)set-info,set-info}.

@item Motd-conference: @var{int}
The number of the conference where "message-of-the-day" messages should
be sent. Defaults to 3. This option is ignored in lyskomd 1.9 and later.
Set this using dbck or the @ref{(protocol-a)set-info,set-info}.

@item News-conference: @var{int}
The number of the conference where news of interest to the readers of
this LysKOM server should be written. This is typically a conference
with very low traffic which everyone shoule be a member of. Clients
should offer new users to join it. Defaults to 4. This option is ignored
in lyskomd 1.9 and later. Set this using dbck or the
@ref{(protocol-a)set-info,set-info}.


@item Message of the day: @var{int}
Default message-of-the-day of this server. The text will be shown
automatically by conforming LysKOM clients when a user logs on. This
option is ignored in lyskomd 1.9 and later. Set this using dbck or the
@ref{(protocol-a)set-info,set-info}.


@item Garb: @var{bool}
Should the database be automatically purged of old texts?  The default
is on.

@item Never save: @var{bool}
Completely disables saving the database. Do not set this to @code{true}
unless you really know what you're doing. The default is @code{false}.

@item Log accesses: @var{path}
This parameter can only be set if the server has been compiled with
@code{LOGACCESSES} defined. It will save a trace of all activity in the
database to a file, for later use in simulations et c. Compiling with
@code{LOGACCESSES} slows the server down quite a lot, so it is normally
not defined.

@item Data file: @var{path}
The path relative to the installation prefix@footnote{The installation
prefix can be specified at compile time, and overridden by the
@code{Prefix:} parameter.} where part of the database is kept. The
default is @file{var/lyskomd/db/lyskomd-data}.

@item Backup file: @var{path}
The path relative to the installation prefix where a backup of the
database is kept. This file will always contain a complete database,
but it may be a little out-of-date. Default is
@file{var/lyskomd/db/lyskomd-backup}.

@item Backup file 2: @var{path}
The path relative to the installation prefix where a previous generation
of the backup of the database is kept. This file may be needed if an
error in the backup file is detected during the creation of the data
file. Default is @file{var/lyskomd/db/lyskomd-backup-prev}.

@item Lock file: @var{path}
Name of the lock file that ensures that @code{dbck} and @code{lyskomd}
never attempt to modify the database at the same time.  It should always
reside in the same directory as the @samp{Data file}.  Default is
@file{var/lyskomd/db/lyskomd-lock}.

@item Text file: @var{path}
The path relative to the installation prefix where the actual texts in
the database are kept. Default is @file{var/lyskomd/db/lyskomd-texts}.

@item Text backup file: @var{path}
When @code{dbck} is run with the @samp{-g} option (@ref{Invoking
dbck}, it will store the previous contents of the text file in the
file specified by this option. The path is relative to the
installation prefix. This file is never used by @code{lyskomd}
itself. Default is @file{var/lyskomd/db/lyskomd-texts-backup}.

@item Backup export directory: @var{path}
When @code{splitkomdb} is run, it will create a copy of the database
in this directory.  The copy will be split in a way that helps to keep
incremental backups of that directory small.  @xref{splitkomdb}.  The
path is relative to the directory specified by @code{Prefix:}.  This
directory is never used by @code{lyskomd} itself.  Default is
@file{var/lyskomd/exportdb}.

@item Number file: @var{path}
@itemx Number temp file: @var{path}
Name of the file where the first unused conference and text numbers
are stored.  This file contains a single line.  It is rewritten each
time a new conference or text is created, to ensure that numbers are
never reused even if the server later crashes before it has time to
save the database.  The information is first written to @code{Number
temp file:}, and then renamed to @code{Number file:}.  The path is
relative to the installation prefix.  Default is
@file{var/lyskomd/db/number.txt} and @file{var/lyskomd/db/number.tmp},
respectively.  Both files must reside on the same partition.

@item Log file: @var{path}
The path relative to the installation prefix where log messages from
lyskomd are written. Default is @file{var/lyskomd.log}.

@item Log statistics: @var{path}
Whenever lyskomd receives a SIGUSR1 it will append a timestamp and
a count of how many different atomic calls have been made in this file.
The path is relative to the installation prefix. Default is
@file{var/lyskomd.stats}.

@item Pid file: @var{path}
When lyskomd is up and running it will write its pid in this file. The
path is relative to the installation prefix. This file is used so the
@code{updateLysKOM} script can easily find out what pid the LysKOM
server has. Default is @file{var/run/lyskomd.pid}.

This file should be removed when the computer reboots, before
@code{komrunning} or @code{updateLysKOM} is run.

@item Memory usage file: @var{path}
When lyskomd exits normally it appends some info on its usage of memory
to this file. The path is relative to the installation prefix. Almost
any memory leak bugs should be detectable by looking in this file.
Default is @file{var/lyskomd.memory}.

@item Aux-item definition file: @var{path}
This file defines which aux-items the server should support and how it
should handle them. You will find the details in
@xref{Aux-Item Definition File}.
The path is relative to the installation prefix. Default is
@file{etc/aux-items.conf}.
This file is re-read if a @samp{SIGWINCH} singal is sent to the server.
@c FIXME (bug 1095): Remove the following warning when bug 1095 is
@c fixed.
@b{Warning:} If the aux-item definition file contains an error so that
it cannot be parsed, the server will call @code{restart_kom()}, which
will cause the server to abort without saving the database.  Always
test the file on a standby system first!

@item Core directory: @var{path}
The Directory where core dumps are written. This path is relative to the
installation prefix. Default is @file{var/lyskomd.cores}.

@item Connection status file: @var{path}
@itemx Connection status temp file: @var{path}
Where to store a status file that contains information about all
connections.  The status is written to the temp file and atomically
renamed to the status file.

The path is relative to the installation prefix.  Defaults are
@file{var/lyskomd.clients} and @file{var/lyskomd.clnt.tmp}.  Both
files must reside on the same file system.  @xref{Files}, for
information about the file format.

@item Status file: @var{path}
This file is created by @code{komrunning} to indicate that lyskomd
should currently not be running.  When this file exists
@code{updateLysKOM} will send it a @samp{SIGTERM} signal, so that it
saves the database and dies.  Default is @file{var/lyskomd/db/status}.

@item Nologin file: @var{path}
If this file exists, the server will not allow any connections at all.
Default is @file{/etc/nologin}.

@item Garb busy postponement: @var{timeval}
The garb only runs while the server is idle.  This determines how
often the garb will check if the server is idle.  Default is @code{20
milliseconds}.

@item Garb timeout: @var{timeval}
How long to sleep when the server is garbage-collecting texts, but has
nothing else important to do.  Default is @code{100 milliseconds}.

@item Sync timeout: @var{timeval}
How long to sleep when lyskomd is saving its database.
Defaults to @code{0 milliseconds}.

@item Permissive sync: @var{bool}
Turning this option on lets any session sync the LysKOM database.
Turning it off restricts the operation to LysKOM administrators. Default
is off.

@item Garb interval: @var{timeval}
How long to wait between each garb sweep.  Defaults to @code{1440
minutes}, which means that 24 hours will pass between each garb sweep.

@item Sync interval: @var{timeval}
How long to wait between syncs. The current version of lyskomd keeps
changes to the database in memory until they are synced to disk. This
parameter specifies how long the server waits before attempting to
dump the database. The default is @code{5 minutes}.

@item Sync retry interval: @var{timeval}
If anything goes wrong while trying to dump the data base (such as if
the disk is full), lyskomd will wait for this long before trying
again. Default is @code{1 minute}.

@item Saved items per call: @var{int}
When the server is saving the database, it does so in the background.
It serves one call from a client, saves a few items to the new database
file, serves another call, et c.  This parameter sets the number of
items (texts, conferences, persons) that are saved after each call.
Default is @code{5}.

@item Penalty per call: @var{int}
Penalty points given to a client once a call is completed.  This
affects the scheduling.  Default is @code{10}.

@item Penalty per read: @var{int}
Penalty points given to a client each time a @code{read(2)} is
performed on the socket connected to the client.  This affects the
scheduling.  Default is @code{1}.

@item Max penalty: @var{int}
Once a client receives this many penalty points, the server will stop
reading from the socket connected to the client.  (Once the server
becomes idle, all penalty points will be aged, so the server will soon
start reading from it again.)  Default is @code{100}.

@item Low penalty: @var{int}
Once the penalty points for a client is reduced below this setting,
the server will start reading from the client again.  This should be
lower than @code{Max penalty}.  Default is @code{20}.

@item Default priority: @var{int}
@itemx Max priority: @var{int}
The default and max scheduling priority of a client.  Both values must
currently be set to @code{0}, which is the default.

@item Default weight: @var{int}
@itemx Max weight: @var{int}
The default and max scheduling weight for a client.  Defaults to
@code{20} and @code{100}.

@item Connect timeout: @var{timeval}
If the client doesn't send the initial handshake (such as
@samp{A27Hceder@@stanly.lysator.liu.se}) within this time period, the
client will be disconnected.  
Default is @code{30 seconds}.

@item Login timeout: @var{timeval}
@itemx Active timeout: @var{timeval}
If nothing is sent to the client for this long, the client will be
disconnected.  Both asynchronous messages and replies to requests from
the clients will reset the timer.  The @samp{Login timout:} value is
used while nobody is logged in on the session.
Default is @code{30 minutes} and @code{11.5 days}, respectively.

@item Max client data length: @var{int}
The maxiumum allowed length for client name and version data. The
default is @code{60}.

@item Max conference name length: @var{int}
The maximum length of conference names. The default is @code{60}.

@item Max password length: @var{int}
Only the first eight characters of the password are currently
significant, even if this number is much larger. The default is
@code{128}.

@item Max what am I doing length: @var{int}
The maximum length of the string permitted in the protocol A call
@ref{(protocol-a)change-what-i-am-doing, change-what-i-am-doing}. The
default is 60.

@item Max username length: @var{int}
The maximum length permitted for user names. Default is 128.

@item Max text length: @var{int}
The maximum length allowed for a text. The default is 131072 characters.

@item Max aux_item length: @var{int}
The maximum length allowed for a single aux-item. The default is 16384
characters.

@item Max broadcast length: @var{int}
The maximum length allowed for broadcast messges. The default is 1024
characters.

@item Max regexp length: @var{int}
The maximum length allowed for regexps in various calls. The default is
1024 characters.

@item Statistic name length: @var{int}
The maximum lenght allowed for the name of a measured statistics.  The
default is 64 characters.

@item Max marks per person: @var{int}
The maximum number of marks a person is allowed to have. The default is
2048.

@item Max marks per text: @var{int}
The maximum number of marks a text can have. The default is 1024.

@item Max recipients per text: @var{int}
The maximum number of recipients of a text. The default is 512.

@item Max comments per text: @var{int}
The maximum number of comments a text can have. The default is 128.

@item Max footnotes per text: @var{int}
The maximum number of footnotes a text can have. The default is 32.

@item Max links per text: @var{int}
The maximum number of misc info items that can be added to a text.

@item Max mark_as_read chunks: @var{int}
@c FIXME: What is this?

@item Max super_conf loop: @var{int}
@c FIXME: What is this?

@item Max accept_async len: @var{int}
Maximum length of list accepted in the accept_async call. Default is
128.

@item Max aux_items deleted per call: @var{int}
Maximum number of aux_items that can be deleted in one call. Default is
128.

@item Max aux_items added per call: @var{int}
Maximum number of aux_items that can be added at once. Default is 128.

@item Max read_ranges per call: @var{int}
Maximum number of read_ranges that can sent in a single request.
Default is 512.

@item Default garb nice: @var{int}
Each conference has a lifetime for texts written in it. The lifetime is
counted in days, and can be set for each conference by the administrator
of the conference. This is the default value assigned to new
conferences. Default is 77 days.

@item Default keep commented nice: @var{int}
A text will not be removed if it has comments newer than a certain
number of days. This number can be set for each conference. This
parameter specifies the default value for that number of days. The
default is 77.

@item Max client message size
The maximum number of bytes that is read or written in a single system
call.  Defaults to 8176.  (Attempts to set it to a larger value will
currently only affect the input.)

@item Max client transmit queue messages: @var{int}
@itemx Max client transmit queue bytes: @var{int}
Max number of pending data blocks (or total number of bytes) in the
reply queue to a client. If there is ever more than this many data
blocks in the queue the client will be disconnected. Each atomic
question typically generates two data blocks. Default is 50 and
100000, respectively.

@item Stale timeout: @var{timeval}
If the transmit queue of a client is full for this long, without the
server being able to send anything to the client, the client will be
disconnected.  Default is 60 minutes.

@item Max simultaneous client replies: @var{int}
This is a performance tuning parameter of little real interest. Default
is 10.

@item Open files: @var{int}
Try to persuade the operating system to allow lyskomd to have this many
open file descriptors simultaneously. Each client that is connected to
the server occupies one file descriptor, and lyskomd needs several file
descriptors for internal purposes. Default is to not use this parameter.

@item Use DNS: @var{bool}
The IP address of a client is looked up using DNS when it connects.
Unfortunately, this lookup blocks the entire server, and it can take
several minutes.  You can disable DNS lookup with this parameter.
Default is on.

@item DNS log threshold: @var{double}
If the @samp{Use DNS:} parameter is true, the server will measure the
time each DNS lookup takes.  If the time exceeds the specified
threshold, an entry will be made in the log.  The value is specified
in seconds.  The default value is 1.5 seconds.  If your libc supports
it, you can enter @code{+inf} to disable logging.

@item Anyone can create new persons: @var{bool}
If this is set, anyone can create a new person, even if he lacks
special bits for doing so. Default is on.

@item Anyone can create new conferences: @var{bool}
If this is set, anyone can create a new conferences, even if he lacks
special bits for doing so. Default is on.

@item Allow creation of persons before login: @var{bool}
If this is set, persons can connect the the server and create a new
person without logging in.  This is how new users register in open
environments. If this option is off, then new persons can only be
created by existing users. The default is on.

@item Default change name capability: @var{bool}
If this is set, new users are created with the ability to change their
own name. Default is on.

@item Ident-authentication: @var{policy}
Decide how strictly the server should use the IDENT protocol.
The policy can take any of three values:

@table @asis
@item @code{off} or @code{never}
Do not use the IDENT protocol.

@item @code{on} or @code{try}
Use it, but allow logins even if the lookup fails.

@item @code{require} or @code{required}
Disallow connections if the server cannot find a IDENT login name.
@end table


@item Log login: @var{bool}
Should logins be logged to the log file?  Default value is off.

@item Cache conference limit: @var{int}
How many conference statuses the server cache should hold in main
memory. Default is 20. This parameter should be set to at least the
number of expected simultaneous logins.

@item Cache person limit: @var{int}
How many person statuses the server cache should hold in main
memory. Default is 20. This parameter should be set to at least the
number of expected simultaneous logins.

@item Cache text_stat limit: @var{int}
How many text statuses the server cache should hold in main
memory. The default is 20. This parameter should be increased on busy
servers.

@item Echo: @var{string}
Write @var{string} in the log when the config file is read.

@item Jubel: @var{pers_no} @var{text_no}
@itemx Jubel: public @var{pers_no} @var{text_no}
States that @var{pers_no} is not allowed to create text number
@var{text_no}. Default is unset. This parameter may be used multiple
times. The form with the string @code{public} means that the text must
have a public conference as recipient.

@item Jubel: @var{pers_no} @var{dividend} @var{remainder}
@item Jubel: public @var{pers_no} @var{dividend} @var{remainder}
States that @var{pers_no} is not allowed to create any text number
@var{T} which meets the condition @var{T} % @var{dividend} == @var{remainder}.
Default is unset. This parameter may be used multiple
times. The form with the string @code{public} means that the text must
have a public conference as recipient.

@item Add members by invitation: @var{bool}
If this is set, then adding others as members to a conference sets the
invitation bit of the membership. If this is off, the membership bit is
set to whatever the caller specifies. The default is on.

@item Allow secret memberships: @var{bool}
If this is set, then memberships may be secret. Otherwise any attempt
to create a secret membership or change an existing membership to a
secret membership will fail. The default is on.

@item Allow reinvitations: @var{bool}
If this is set, then it is possible to set the invitation bit of a
membership even after it has been cleared. If it is not set, then the
invitation bit of a conference type can only be set when the
membership is created. It can be cleared at any time. The default is
off.

@item lyskomd path: @var{path}
Path to the @code{lyskomd} binary.  This is used by @code{updateLysKOM}
to find the right program to run.  Defaults to @file{sbin/lyskomd}.

@item savecore path: @var{path}
Path to the @code{savecore-lyskom} program.  If a file named
@file{core} exists in the directory specified with @code{Core
directory} when @code{updateLysKOM} is about to start @code{lyskomd},
this program will be called first.  It could, for instance, move the
core file so that it is available for later debugging.  The script
supplied by the distribution does nothing.
Defaults to @file{sbin/savecore-lyskom}.

@item Normal shutdown time: @var{int}
In a normal setup, @code{updateLysKOM} will be run from @code{cron} once
every ten minutes or so.  If it detects that it has taken @code{lyskomd}
more than @var{int} minutes to shut down it will print a warning
message.

@item Mail after downtime: @var{int}
@itemx Mail until downtime: @var{int}
If @code{lyskomd} has been down for X minutes, where @code{Mail after
downtime} <= X < @code{Mail until downtime}, @code{updateLysKOM} will
send a mail message to the mail address found on the first line of the
status file.  Actually, it is the age of the status file (named with
@code{Status file}) that is measured.
The defaults are 60 and 120, respectively.

@item sendmail path: @var{path}
Path to the @code{sendmail}-compatible program that
@code{updateLysKOM} should use to send mail.  This program will be
invoked with a @samp{-t} option via a @samp{popen()} call.  It should
accept an email header, a blank line, an email body, and a terminating
line consisting of a single @samp{.} on standard input.
The default is found at configure time.  The special value @samp{:}
means that no mail will ever be sent.

@end table


@node Aux-Item Definition File
@section Aux-Item Definition File

The default aux-item definition file should not be changed unless it is
really necessary. The need to change the definitions will probably only
arise at installations used for client or server development.

The location of the aux-item definition file is specified by the
@code{Aux-item definition file} option in the server configuration
file. The default location is @file{/usr/lyskom/etc/aux-items.conf}.


@subsection Syntax of the Aux-Item Definition File

The aux-item definition file contains a sequence of aux-item
definitions. Each definition specifies one type of predefined aux-item:
its number, name, and properties. Empty lines and all characters from a
# character to the end of the line are ignored.

Each entry has the following format:

@example
        tag : name (target, target, ... )
        @{
            field = value;
            field = value;
            ...
        @}
@end example

@var{tag} is an integer, the aux-item's tag. If a tag is defined more than
once, the last definition is used.

The @var{target}s specify what kind of objects aux-items with tag @var{tag}
can be added to. Valid targets are:

@table @code
@item any
Aux-items with the specified tag can be added to any object in the
database. This is shorthand for @code{text,conference,letterbox,server}.

@item text
Aux-items with the specified tag can be added to texts.

@item conference
Aux-items with the specified tag can be added to conferences that are
@emph{not} letterboxes.

@item letterbox
Aux-items with the specified tag can be added to conferences that are
letterboxes.

@item server
Aux-items with the specified tag can be added to the server itself.

@end table

It is legal to add one of the keywords @code{create} or @code{modify}
before any target except @code{server}. If @code{create} is specified,
aux-items with the specified tag can only be added when an object is
being created. They cannot be added later. If @code{modify} is
specified, aux-items with the specified tag can only be added after an
object has been created. They cannot be added when the object is being
created.

Each @var{field}/@var{value} pair specifies a property of aux-items with the
specified tag. Most values are boolean or trillian. Legal values for
either type are @code{true} and @code{false}. Boolean values have
reasonable defaults; trillian values can be unset.

@table @code

@item author-only
Boolean, default false. When true, only the author of a text or
supervisor of a conference can create items with this tag.
This has no effect on items placed on the system.

@item supervisor-only
Boolean, default false. When true, only the supervisors of the author or
letterbox can create items with this tag. In all likelihood, the
implementation of this flag is screwed up in version 2.0 of lyskomd.
This has no effect on items placed on the system.

@item system-only
Boolean, default false. When true, only the server can initiate creation
of items with this tag. This is normally used for items that are created
automatically in response to events in the system.

@item permanent
Boolean, default false. When true, aux-items with this tag cannot be
deleted once they have been created.  (They will be deleted
automatically when the object they are assigned to is deleted.)

@item unique
Boolean, default false. When true, there can only be one non-deleted
item with this tag per creator.

@item unique-data
Boolean, default false. When true, there can only be one non-deleted
item with this tag that contains the same data (regardless of who
creates the item).

@item owner-delete
Boolean, default false. When true, the owner of the object that this
aux-item is attached to can always delete the aux-item.  For a text,
the owner is defined as the supervisor(s) of the author of the text.
For a conference, the owner is defined as the supervisor(s) of the
conference.

@item inherit-limit
Integer, default 0. The maximum number of times items with this tag can
be inherited, plus one. Zero means an unlimited number of times, one
means no times, 2 means once and so forth. This number overrides the
inherit-limit set by the client only if that number is higher than this
one.

@item inherit
Trillian. When set, the inherit bit on new items with this tag is forced
to the specified value.

@item secret
Trillian. When set, the secret bit on new items with this tag is forced
to the specified value.

@item hide-creator
Trillian. When set, the hide-creator bit on new items with this tag is
forced to the specified value.

@item dont-garb
Trillian. When set, the dont-garb bit on new items will be forced to the
specified value.

@item reserved-2
@item reserved-3
@item reserved-4
Trillian. When set, these flags force the values of the three reserved
bits in the aux-item flags field. These should only be used by lyskomd
developers, and then only very carefully.

@item validate

String or function, default none. When set to a string, this specifies a
regexp that must match the data field in newly created items with this
tag. If the regexp fails to match, then the item will not be created.
The syntax for strings is essentially the same as the syntax used in C
files. When set to a function, this specified a built-in validation
function to call.

The following validator functions are currently implemented:

@table @code

@item existing-readable-text
Creation is only allowed if the item contains the number of an existing
text that the item creator has permission to read.

@end table


@end table

There are a few fields which specify actions the server is to take when
something happens to aux-items with the specified tag. Each of these
values is a function specification, the name of a trigger function
defined in lyskomd. The syntax for functions is the name followed by
an empty pair of parens. It is not possible to pass arguments to the
functions yet.

@table @code
@item add-trigger
Function to call when an item with the specified tag is added to an
object.

@item delete-trigger
Function to call when an item with the specified tag is scheduled for
deletion.

@item undelete-trigger
Function to call when an item with the specified tag scheduled for
deletion is unscheduled. It should undo the effects of the delete
trigger.
@end table

The following trigger functions are currently defined:

@table @code
@item mark-text
Increase the mark count for the text the item refers to. The item must
contain the number of a text. This trigger should be combined with the
existing-readable-text validation function.

@item unmark-text
Decrease the mark count for the text the item refers to. The item must
contain the number of a text. This trigger should be combined with the
existing-readable-text validation function.

@item link-faq
Create a faq-for-conf item linked to a faq-text item. This trigger is
used exclusively for faq-text items. The item must contain the number of
a text. This trigger must be combined with the existing-readable-text
validation function.

@end table




@node Running lyskomd
@chapter Running lyskomd

This section explains how to run lyskomd, the files it uses and how it
can be controlled while running.

@menu
* Invoking lyskomd::            How to run lyskomd.
* Signals::                     How to control lyskomd with Unix signals.
* Files::                       Files used by lyskomd.
@end menu


@node Invoking lyskomd
@section Invoking lyskomd

@example
        lyskomd [-f] [-d] [@var{config-file}]
@end example

The option @samp{-d} adds one to the debug level. The amount of output
on stderr/to the log file is increased for each time the option is
specified on the command line.

Using one @samp{-d} makes the process print a `>' for every timeout, a
message for every person that is connecting or disconnecting and a
message for every successful or unsuccessful communication to the
process.

The option @samp{-f} tells lyskomd to stay in forground mode, and not
run in the background as a daemon.  The output that is normally
written to the log file is instead sent to stderr.

The optional @var{config-file} argument can be used to specify the server
configuration file. @xref{Server Configuration File}.


@node Signals
@section Signals

It is possible to control some aspects of lyskomd using Unix signals.
The following signals have special meaning to the server:

@table @samp
@item SIGTERM
@itemx SIGHUP
@itemx SIGINT
Logs out all sessions, saves the database and exits normally.  Use
@samp{SIGTERM}; the other signals currently have the same
functionality, but that may be changed in the future.

@item SIGQUIT
Saves the database and dump core. (This should only be used for
debugging purposes.)

@item SIGUSR1
Print statistics about how often different commands have been used
since the process started.

@item SIGUSR2
Forks a child that immediately dumps core. The main process just waits
until the child is done and then continues.

@item SIGWINCH
Re-read the aux-item definition file.
@c FIXME (bug 1095): Remove the following warning when bug 1095 is
@c fixed.
@b{Warning:} If the aux-item definition file contains an error so that
it cannot be parsed, the server will call @code{restart_kom()}, which
will cause the server to abort without saving the database.  Always
test the file on a standby system first!
@end table


@node Files
@section Files Used by lyskomd

All file names can be changed in the server configuration file.
@xref{Parameters}.

@table @file
@item /usr/lyskom
Default value of the @code{Prefix} parameter. The default of this value
is set at compile time, but it can be changed in the server
configuration file.  @xref{Parameters}.

@item @var{prefix}/var/lyskomd/db/lyskomd-data
Half of the database: all status information.

@item @var{prefix}/var/lyskomd/db/lyskomd-texts
The other half of the database: the actual texts.

@item @var{prefix}/var/lyskomd/db/lyskomd-backup
A backup copy of @file{lyskomd-data}. Never, ever delete this file
unless you know what you are doing, or you may lose the entire data
base. Most of the time this is the only complete database file!

@item @var{prefix}/var/lyskomd/db/number.txt
Information about the highest used text- and conference numbers.  In
case of a crash, some objects may be lost.  This file ensures that
even if that happens, their numbers will not be reused.

@item @var{prefix}/var/run/lyskomd.pid
File with the pid of the lyskom-process.

@item @var{prefix}/var/lyskomd.memory
On normal exit, @code{lyskomd} will append some statistics to this file. 
It can be used for detecting memory leaks.

@item @var{prefix}/etc/aux-items.conf
This file contains definitions of the aux-items that the server should
support.  It is read by @code{lyskomd} at startup.

@item @var{prefix}/var/lyskomd.clients
A list of all currently connected clients, maintained by the server.
The data about each client is collected on a single line:

@itemize @bullet
@item The file descriptor
@item The session number
@item @samp{1} if the handshake is OK, the reverse DNS has completed,
and the IDENT lookup has completed.  @samp{0} otherwise.
@item The IP address of the client
@item The port number of the client
@end itemize

In the following example, we see that file descriptor 437 is used by
session 330978, and the connection is from 130.236.254.83:3156.

@example
437 330978 130.236.254.83 3156
@end example

@item /etc/nologin
If this file exists, lyskomd will not allow anyone to connect to the
server. This path can be set with the @code{Nologin file} parameter in
the server configuration file.

@end table


@node Invoking updateLysKOM
@chapter Invoking updateLysKOM

@example
        updateLysKOM [-c @var{config-file}] [ -v ] [ -V ]
@end example

@code{updateLysKOM} determines if @code{lyskomd} should be running.  It
can start or stop @code{lyskomd} if needed.  It uses the same
configuration file as @code{lyskomd} (@pxref{Server Configuration
File}).  You can use @samp{-c @var{config-file}} to override the
compiled-in default.  Note, however, that this option is not passed
along to @code{lyskomd} if @code{updateLysKOM} starts it, so the option
should be used with extreme caution.

@samp{-v} and @samp{-V} causes @code{updateLysKOM} to report its version
number and exit.

@code{updateLysKOM} is normally run from @code{cron};
@pxref{Administration}.

@node Invoking komrunning
@chapter Invoking komrunning

@example
        komrunning [-c config-file] [start | stop]
        komrunning -v | -V
@end example

@code{komrunning}, when invoked with no arguments, reports whether
@code{lyskomd} is currently running or not, and whether it should be
running or not.  @samp{komrunning start} attempts to start
@code{lyskomd}.  @samp{komrunning stop} attempts to stop @code{lyskomd},
and it will not return until the server has saved its database and
exited.

@code{komrunning} uses the same configuration file as @code{lyskomd}
(@pxref{Server Configuration File}).  You can use @samp{-c
@var{config-file}} to override the compiled-in default.  Note, however,
that this option is not passed along to @code{updateLysKOM} if
@code{komrunning} invokes it, so the option should be used with extreme
caution.

The @code{komrunning} can be installed in @file{/etc/init.d/}.  Be
careful, however, to ensure that the pid file is removed earlier during
the boot sequence.

@samp{-v} and @samp{-V} causes @code{komrunning} to report its version
number and exit.

@node Administration
@chapter Administration

The first thing you will have to do is to follow the instructions in the
files @file{INSTALL} and @file{README}. This will set up the LysKOM
system with a database containing a few necessary conferences and one
person - the administrator.

Once the LysKOM system is running, there is not much you will have to do
to keep it that way. One thing to remember is that the current release
of the server has an incomplete handling of garbage collection of the
database. The database is split into two files, the information file and
the text file. Newly written texts are concatenated to the text file and
old texts are never removed. The information file contains information
about conferences, users and where in the text file the texts are. This
file is properly garbage collected, but not the text file.

There is a program called @code{dbck} (Data Base Check) which is used
to check the consistency of the LysKOM database. This program can also
be used to shrink the text file. To do this, just type @samp{dbck
-g}. @xref{DBCK Reference}. When @code{dbck} is to be run on the
database, the LysKOM server @emph{must} be stopped, or unrepairable
damage may result. See below for a description on how to stop the
server.

There is a program called @code{updateLysKOM} which is used to ensure
continuous operation. This program should be run with certain intervals,
for instance from @code{cron}. If the LysKOM server has died for some
reason, @code{updateLysKOM} restarts it. If the server is still running
properly, @code{updateLysKOM} sends a signal (@samp{SIGUSR1}) to it,
which causes the server to write some statistics to a file named
@file{var/lyskomd.stats} in the lyskom directory.

Taking the server down cleanly can be done in two ways: through the use
of the LysKOM protocol on a socket, preferably through the use of a
suitable client, or by sending the signal @samp{SIGTERM} to it. This will
cause the server to save the database and close all client
connections. It will also create a file named @file{var/lyskomd.memory} in
which the memory usage of the server is reported.

To prevent @code{updateLysKOM} from restarting a server, create a file
named @file{/usr/lyskom/var/lyskomd/db/status}. The file should
contain a valid mail address on the first line. @code{updateLysKOM}
will not restart the server as long as that file exists. In addition,
if the file is between 1 and 2 hours old (configurable) an email will
be sent to the mail address found in the file. If the file is older
than that, an error message will be printed on stderr and
@code{updateLysKOM} will exit with a non-zero exit status. cron is
expected to deliver the error message to an operator.

The shell script @code{komrunning} can be used to start and stop the
LysKOM server. With no arguments, it will report the status.

@example
        komrunning stop
@end example

will (attempt to) shut down the server, creating the file
@file{/usr/lyskom/var/lyskomd/db/status}.  If the user running
@code{komrunning} doesn't have permission to send signals to
@code{lyskomd} the actual shutdown will be delayed until the next time
that @code{updateLysKOM} is run.

@example
        komrunning start
@end example

will restart the server.  The actual starting of the server will be done
by @code{updateLysKOM} the next time it is run.  @code{komrunning} only
removes the  @file{/usr/lyskom/var/lyskomd/db/status} file.


@node Bugs
@chapter Known Bugs

@itemize @bullet
@item lyskomd should re-read the config file when a @samp{SIGHUP} is
received.

@item The security policy is vague and the implementation is frayed at
the edges.

@item The choice of asynchronous messages is not very good.

@item The server uses too much memory.

@end itemize




@c ======================================================================
@c =====================================================================