syslog.8

<B>Digital的Unix操作系统VAX 4.2源码</B>

.TH SYSLOG 8
.SH NAME
syslog \- log systems messages
.SH SYNOPSIS
/etc/syslog [
.BI \-m N
] [
.BI \-f name
]
.SH DESCRIPTION
.I Syslog
reads datagrams from an IPC port
(currently port 2222, for no good reason)
and logs each line it reads into a set of files
described by the configuration file
/etc/syslog.conf.
.I Syslog
configures when it starts up
and whenever it receives a hangup signal.
.PP
Each message is one line.
A message can contain a priority code,
marked by a digit in angle braces
at the beginning of the line.
Priorities are defined in <syslog.h>, as follows:
.IP LOG_ALERT \w'LOG_WARNING'u+2n
this priority should essentially never
be used.  It applies only to messages that
are so important that every user should be
aware of them, e.g., a serious hardware failure.
.IP LOG_SALERT
messages of this priority should be
issued only when immediate attention is needed
by a qualified system person, e.g., when some
valuable system resource dissappears.  They get
sent to a list of system people.
.IP LOG_EMERG
Emergency messages are not sent to users,
but represent major conditions.  An example
might be hard disk failures.  These could be
logged in a separate file so that critical
conditions could be easily scanned.
.IP LOG_ERR
these represent error conditions, such as soft
disk failures, etc.
.IP LOG_CRIT
such messages contain critical information,
but which can not be classed as errors, for example,
'su' attempts.
Messages of this priority and higher
are typically logged on the system console.
.IP LOG_WARNING
issued when an abnormal condition has been
detected, but recovery can take place.
.IP LOG_NOTICE
something that falls in the class of
"important information"; this class is informational
but important enough that you don't want to throw
it away casually.
Messages without any priority assigned to them
are typically mapped into this priority.
.IP LOG_INFO
information level messages.  These messages
could be thrown away without problems, but should
be included if you want to keep a close watch on
your system.
.IP LOG_DEBUG
it may be useful to log certain debugging
information.  Normally this will be thrown away.
.PP
It is expected that the kernel will not log anything below
LOG_ERR priority.
(Note: kernel logging is not implemented at this time.)
.PP
The configuration file is in two sections
seperated by a blank line.
The first section defines files that
.I syslog
will log into.
Each line contains
a single digit which defines the lowest priority
(highest numbered priority)
that this file will receive,
an optional asterisk
which guarantees that something gets output
at least every 20 minutes,
and a pathname.
The second part of the file
contains a list of users that will be
informed on SALERT level messages.
For example, the configuration file:
.nf

	5*/dev/console
	8/usr/spool/adm/syslog
	3/usr/adm/critical

	eric
	kridle
	kalash

.fi
logs all messages of priority 5 or higher
onto the system console,
including timing marks every 20 minutes;
all messages of priority 8 or higher
into the file /usr/spool/adm/syslog;
and all messages of priority 3 or higher
into /usr/adm/critical.
The users ``eric'', ``kridle'', and ``kalash''
will be informed on any subalert messages.
.PP
The flags are:
.IP \-m 0.5i
Set the mark interval to
.I N
(default 20 minutes).
.IP \-f
Specify an alternate configuration file.
.IP \-d
Turn on debugging (if compiled in).
.PP
To bring
.I syslog
down,
it should be sent a terminate signal.
It logs that it is going down
and then waits approximately 30 seconds
for any additional messages to come in.
.PP
There are some special messages that cause control functions.
``<*>N'' sets the default message priority to
.I N.
``<$>'' causes
.I syslog
to reconfigure
(equivalent to a hangup signal).
This can be used in a shell file run automatically
early in the morning to truncate the log.
.SH FILES
/etc/syslog.conf \- the configuration file
.SH BUGS
LOG_ALERT and LOG_SUBALERT messages
should only be allowed to privileged programs.
.PP
Actually,
.I syslog
is not clever enough to deal with kernel error messages.
.SH SEE\ ALSO
syslog(3)