System Log

The mail services log most errors using the syslogd program. The default is for syslogd to send messages to the loghost.

You can define a system called loghost in the /etc/hosts file to hold all logs for an entire NIS domain. The system log is supported by the syslogd program. You specify a loghost in /etc/hosts. If no loghost is specified, then error messages from syslogd are not reported.

Example 2-1 shows the default /etc/syslog.conf file:

Example 2-1 Default /etc/syslog.conf File

#ident "@(#)syslog.conf   1.3        93/12/09 SMI"  /* SunOS 5.0 */  #
# Copyright (c) 1994 by Sun Microsystems, Inc. 
#
# syslog configuration file. 
# 
# This file is processed by m4 so be careful to quote (`') names 
# that match m4 reserved words. Also, within ifdef's, arguments 
# containing commas must be quoted. 
# 
# Note: Have to exclude user from most lines so that user.alert 
#       and user.emerg are not included, because old sendmails 
#       have no 4.2BSD based systems doing network logging, you 
#       can remove all the special cases for "user" logging.
# *.err;kern.debug;auth.notice;user.none	        /dev/console 
*.err;kern.debug;daemon,auth.notice;mail.crit;user.none /var/adm/messages 
*.alert;kern.err;daemon.err;user.none            operator 
*.alert;user.none	                               root 
*.emerg;user.none	                               * 
# if a non-loghost machine chooses to have authentication messages 
# sent to the loghost machine, un-comment out the following line:
#auth.notice         ifdef(`LOGHOST', /var/log/authlog, @loghost) 
mail.debug           ifdef(`LOGHOST', /var/log/syslog, @loghost) 
# 
# non-loghost machines will use the following lines to cause "user" 
# log messages to be logged locally. 
# 
ifdef(`LOGHOST', , 
user.err             /dev/console 
user.err             /var/adm/messages 
user.alert           `root, operator' 
user.emerg           * 
)

You can change the default configuration by editing the /etc/syslog.conf file. You must restart the syslog daemon for any changes to take effect. You can add these selections to the file to gather information about mail:

• mail.alert--Messages about conditions that should be fixed now

• mail.crit--Critical messages

• mail.warning--Warning messages

• mail.notice--Messages that are not errors, but might need attention

• mail.info--Informational messages

• mail.debug--Debugging messages

The following entry sends a copy of all critical, informational and debug messages to /var/log/syslog.

mail.crit;mail.info;mail.debug			/var/log/syslog

Each line in the system log contains a time stamp, the name of the system that generated it, and a message. The syslog file can log a large amount of information.

The log is arranged as a succession of levels. At the lowest level, only unusual occurrences are logged. At the highest level, even the most mundane and uninteresting events are recorded. As a convention, log levels under 10 are considered "useful." Log levels higher than 10 are usually used for debugging. See the "Customizing System Message Logging" in System Administration Guide, Volume II for information about loghost and the syslogd program.