syslogd - log systems messages
syslogd [ -fconfigfile ] [ -mmarkinterval ] [ -d ]
Syslogd reads and logs messages into a set of files described by the configuration file
/etc/syslog.conf. Each message is one line. A message can contain a priority code,
marked by a number in angle braces at the beginning of the line. Priorities are defined
in <sys/syslog.h>. Syslogd reads from the UNIX domain socket /dev/log, from an Internet
domain socket specified in /etc/services, and from the special device /dev/klog (to read
Syslogd configures when it starts up and whenever it receives a hangup signal. Lines in
the configuration file have a selector to determine the message priorities to which the
line applies and an action. The action field are separated from the selector by one or
Selectors are semicolon separated lists of priority specifiers. Each priority has a
facility describing the part of the system that generated the message, a dot, and a level
indicating the severity of the message. Symbolic names may be used. An asterisk selects
all facilities. All messages of the specified level or higher (greater severity) are
selected. More than one facility may be selected using commas to separate them. For
Selects all facilities at the emerg level and the mail and daemon facilities at the crit
Known facilities and levels recognized by syslogd are those listed in syslog(3) without
the leading ``LOG_''. The additional facility ``mark'' has a message at priority LOG_INFO
sent to it every 20 minutes (this may be changed with the -m flag). The ``mark'' facility
is not enabled by a facility field containing an asterisk. The level ``none'' may be used
to disable a particular facility. For example,
Sends all messages except mail messages to the selected file.
The second part of each line describes where the message is to be logged if this line is
selected. There are four forms:
o A filename (beginning with a leading slash). The file will be opened in append mode.
o A hostname preceeded by an at sign (``@''). Selected messages are forwarded to the
syslogd on the named host.
o A comma separated list of users. Selected messages are written to those users if they
are logged in.
o An asterisk. Selected messages are written to all logged-in users.
Blank lines and lines beginning with `#' are ignored.
For example, the configuration file:
logs all kernel messages and 20 minute marks onto the system console, all notice (or
higher) level messages and all mail system messages except debug messages into the file
/usr/spool/adm/syslog, and all critical messages into /usr/adm/critical; kernel messages
of error severity or higher are forwarded to ucbarpa. All users will be informed of any
emergency messages, the users ``eric'' and ``kridle'' will be informed of any alert mes-
sages, and the user ``ralph'' will be informed of any alert message, or any warning mes-
sage (or higher) from the authorization system.
The flags are:
-f Specify an alternate configuration file.
-m Select the number of minutes between mark messages.
-d Turn on debugging.
Syslogd creates the file /var/run/syslog.pid, if possible, containing a single line with
its process id. This can be used to kill or reconfigure syslogd.
To bring syslogd down, it should be sent a terminate signal (e.g. kill `cat /var/run/sys-
/etc/syslog.conf the configuration file
/var/run/syslog.pid the process id
/dev/log Name of the UNIX domain datagram log socket
/dev/klog The kernel log device
4.2 Berkeley Distribution November 16, 1996 SYSLOGD(8)