sysklogd.8

制作2.6内核的CLFS时 sysklogd-1.5.tar.gz包

.\" Copyright 1994 Dr. Greg Wettstein, Enjellic Systems Development.
.\" Copyright 2004,6,7 Martin Schulze <[e-mail]>
.\" May be distributed under the GNU General Public License
.\"
.TH SYSKLOGD 8 "27 May 2007" "Version 1.5" "Linux System Administration"
.SH NAME
sysklogd \- Linux system logging utilities.
.SH SYNOPSIS
.B syslogd
.RB [ " \-a "
.I socket
]
.RB [ " \-d " ]
.RB [ " \-f "
.I config file
]
.RB [ " \-h " ] 
.RB [ " \-l "
.I hostlist
]
.RB [ " \-m "
.I interval
] 
.RB [ " \-n " ]
.RB [ " \-p"
.IB socket 
]
.RB [ " \-r " ]
.RB [ " \-s "
.I domainlist
]
.RB [ " \-v " ]
.SH DESCRIPTION
.B Sysklogd
provides two system utilities which provide support for
system logging and kernel message trapping.  Support of both internet and
unix domain sockets enables this utility package to support both local
and remote logging.

System logging is provided by a version of 
.BR syslogd (8)
derived from the
stock BSD sources.  Support for kernel logging is provided by the
.BR klogd (8)
utility which allows kernel logging to be conducted in either a
standalone fashion or as a client of syslogd.

.B Syslogd
provides a kind of logging that many modern programs use.  Every logged
message contains at least a time and a hostname field, normally a
program name field, too, but that depends on how trusty the logging
program is.

While the
.B syslogd
sources have been heavily modified a couple of notes
are in order.  First of all there has been a systematic attempt to
insure that syslogd follows its default, standard BSD behavior.
The second important concept to note is that this version of syslogd
interacts transparently with the version of syslog found in the
standard libraries.  If a binary linked to the standard shared
libraries fails to function correctly we would like an example of the
anomalous behavior.

The main configuration file
.I /etc/syslog.conf
or an alternative file, given with the 
.B "\-f"
option, is read at startup.  Any lines that begin with the hash mark
(``#'') and empty lines are ignored.  If an error occurs during parsing
the whole line is ignored.
.SH OPTIONS
.TP
.BI "\-a " "socket"
Using this argument you can specify additional sockets from that
.B syslogd
has to listen to.  This is needed if you're going to let some daemon
run within a chroot() environment.  You can use up to 19 additional
sockets.  If your environment needs even more, you have to increase
the symbol
.B MAXFUNIX
within the syslogd.c source file.  An example for a chroot() daemon is
described by the people from OpenBSD at
<http://www.guides.sk/psionic/dns/>.
.TP
.B "\-d"
Turns on debug mode.  Using this the daemon will not proceed a 
.BR fork (2)
to set itself in the background, but opposite to that stay in the
foreground and write much debug information on the current tty.  See the
DEBUGGING section for more information.
.TP
.BI "\-f " "config file"
Specify an alternative configuration file instead of
.IR /etc/syslog.conf ","
which is the default.
.TP
.BI "\-h "
By default syslogd will not forward messages it receives from remote hosts.
Specifying this switch on the command line will cause the log daemon to
forward any remote messages it receives to forwarding hosts which have been
defined.
This can cause syslog loops that fill up hard disks quite fast and
thus needs to be used with caution.
.TP
.BI "\-l " "hostlist"
Specify a hostname that should be logged only with its simple hostname
and not the fqdn.  Multiple hosts may be specified using the colon
(``:'') separator.
.TP
.BI "\-m " "interval"
The
.B syslogd
logs a mark timestamp regularly.  The default
.I interval
between two \fI-- MARK --\fR lines is 20 minutes.  This can be changed
with this option.  Setting the
.I interval
to zero turns it off entirely.  Depending on other log messages
generated these lines may not be written consecutively.
.TP
.B "\-n"
Avoid auto-backgrounding.  This is needed especially if the
.B syslogd
is started and controlled by
.BR init (8).
.TP
.BI "\-p " "socket"
You can specify an alternative unix domain socket instead of
.IR /dev/log "."
.TP
.B "\-r"
This option will enable the facility to receive message from the
network using an internet domain socket with the syslog service (see 
.BR services (5)).
The default is to not receive any messages from the network.

This option is introduced in version 1.3 of the sysklogd
package.  Please note that the default behavior is the opposite of
how older versions behave, so you might have to turn this on.
.TP
.BI "\-s " "domainlist"
Specify a domainname that should be stripped off before
logging.  Multiple domains may be specified using the colon (``:'')
separator.
Please be advised that no sub-domains may be specified but only entire
domains.  For example if
.B "\-s north.de"
is specified and the host logging resolves to satu.infodrom.north.de
no domain would be cut, you will have to specify two domains like:
.BR "\-s north.de:infodrom.north.de" .
.TP
.B "\-v"
Print version and exit.
.SH SIGNALS
.B Syslogd
reacts to a set of signals.  You may easily send a signal to
.B syslogd
using the following:
.IP
.nf
kill -SIGNAL `cat /var/run/syslogd.pid`
.fi
.PP
.TP
.B SIGHUP
This lets
.B syslogd
perform a re-initialization.  All open files are closed, the
configuration file (default is 
.IR /etc/syslog.conf ")"
will be reread and the
.BR syslog (3)
facility is started again.
.TP
.B SIGTERM
The
.B syslogd
will die.
.TP
.BR SIGINT ", " SIGQUIT
If debugging is enabled these are ignored, otherwise 
.B syslogd
will die.
.TP
.B SIGUSR1
Switch debugging on/off.  This option can only be used if
.B syslogd
is started with the
.B "\-d"
debug option.
.TP
.B SIGCHLD
Wait for childs if some were born, because of wall'ing messages.
.SH CONFIGURATION FILE SYNTAX DIFFERENCES
.B Syslogd
uses a slightly different syntax for its configuration file than
the original BSD sources.  Originally all messages of a specific priority
and above were forwarded to the log file.
.IP
For example the following line caused ALL output from daemons using
the daemon facilities (debug is the lowest priority, so every higher
will also match) to go into 
.IR /usr/adm/daemons :
.IP
.nf
	# Sample syslog.conf
	daemon.debug			/usr/adm/daemons
.fi
.PP
Under the new scheme this behavior remains the same.  The difference
is the addition of four new specifiers, the asterisk (\fB*\fR)
wildcard, the equation sign (\fB=\fR), the exclamation mark
(\fB!\fR), and the minus sign (\fB-\fR).

The \fB*\fR specifies that all messages for the
specified facility are to be directed to the destination.  Note that
this behavior is degenerate with specifying a priority level of debug.
Users have indicated that the asterisk notation is more intuitive.

The \fB=\fR wildcard is used to restrict logging to the specified priority
class.  This allows, for example, routing only debug messages to a
particular logging source.
.IP
For example the following line in
.I syslog.conf
would direct debug messages from all sources to the
.I /usr/adm/debug
file.
.IP
.nf
	# Sample syslog.conf
	*.=debug			/usr/adm/debug
.fi
.PP
.\" The \fB!\fR as the first character of a priority inverts the above
.\" mentioned interpretation.
The \fB!\fR is used to exclude logging of the specified
priorities.  This affects all (!) possibilities of specifying priorities.
.IP
For example the following lines would log all messages of the facility
mail except those with the priority info to the
.I /usr/adm/mail 
file.  And all messages from news.info (including) to news.crit
(excluding) would be logged to the
.I /usr/adm/news
file.
.IP
.nf
	# Sample syslog.conf
	mail.*;mail.!=info		/usr/adm/mail
	news.info;news.!crit	/usr/adm/news
.fi
.PP
You may use it intuitively as an exception specifier.  The above
mentioned interpretation is simply inverted.  Doing that you may use

.nf
	mail.none
.fi
or
.nf
	mail.!*
.fi
or
.nf
	mail.!debug
.fi

to skip every message that comes with a mail facility.  There is much
room to play with it. :-)

The \fB-\fR may only be used to prefix a filename if you want to omit
sync'ing the file after every write to it.

This may take some acclimatization for those individuals used to the
pure BSD behavior but testers have indicated that this syntax is
somewhat more flexible than the BSD behavior.  Note that these changes
should not affect standard
.BR syslog.conf (5)