AIX 5L Problem Determination - IBM Redbooks

6.6 The syslogd daemon
The syslogd daemon receives information from other daemons and sends it to
files, terminals, users, or other machines. Depending on its configuration, it only
logs critical errors or debugging ouput. By default the file has no active entries.
The syslogd daemon is started by /etc/rc.tcpip. The daemon is configured by
/etc/syslog.conf, in which the priority of the information, its source, and where it
should be sent to are specified.
The syslogd daemon is a subsystem of the System Resource Controller (SRC)
and can be manipulated by the SRC commands described in Table 6-5.
Table 6-5 System Resource Controller commands
SRC
commands
Description
startsrc Starts a subsystem, group of subsystems, or a subserver
stopsrc Stops a subsystem, group of subsystems, or a subserver
lssrc Gets the status of a subsystem, group of subsystems, or a
subserver
The syslogd daemon creates the /etc/syslog.pid file, which contains a single line
with the command process ID used to end or reconfigure the syslogd daemon.
The /usr/include/sys/syslog.h include file defines the facility and priority codes
used by the configuration file. Locally written applications use the definitions
contained in the syslog.h file to log messages using the syslogd daemon.
The syslog subroutine writes messages onto the system log maintained by the
syslogd command. The message is obtained from the errno global variable.
Messages are read by the syslogd command and written to the system console
or log file, or forwarded to the syslogd command on the appropriate host.
Messages are tagged with codes indicating the type of priority for each. A priority
is encoded as a facility, which describes the part of the system generating the
message, and as a level, which indicates the severity of the message.
The syslogd daemon reads a datagram socket and sends each message line to
a destination described by the /etc/syslog.conf configuration file. The syslogd
daemon reads the configuration file when it is activated and when it receives a
hangup signal. The syslogd daemon creates the /etc/syslog.pid file, which
contains a single line with the command process ID used to end or reconfigure
the syslogd daemon. A terminate signal sent to the syslogd daemon ends the
daemon. The syslogd daemon logs the end-signal information and terminates
immediately.
130 IBM ^ Certification Study Guide - AIX 5L Problem Determination Tools and Techniques