syslogd(1M)

Options

syslogd recognizes the following options:

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 kill syslogd, send it a terminate signal:

To make syslogd, re-read its configuration file, send it a HANGUP signal:

syslogd collects messages from the UNIX domain socket /dev/log.un, an Internet domain socket specified in /etc/services, the named pipe /dev/log, and from the kernel log device /dev/klog. By default, local programs calling syslog() send log messages to the UNIX domain socket (see syslog(3C)). If UNIX domain sockets are not configured on the system, they write to the named pipe instead. If INET domain sockets are not configured, syslogd does not receive messages forwarded from other hosts, nor does it forward messages (see below).

Each message is one line. A message can contain a priority code and facility code as the second field of the line. Priorities and Facilities are defined in the header file <syslog.h>.

When syslogd is invoked using /sbin/init.d/syslogd script, user can update the required options in /etc/rc.config.d/syslogd file. By default /etc/rc.config.d/syslogd contains -D option. Before starting the syslogd command, the /sbin/init.d/syslogd script recreates /var/adm/syslog/syslog.log after putting the contents into the file /var/adm/syslog/OLDsyslog.log. By default, OLDsyslog.log is overwritten by the contents of syslog.log. If you want to retain the contents of the previous OLDsyslog.log file, configure PREV_OLDSYSLOG_LINES in /etc/rc.config.d/syslogd. You can set the parameter to the number of lines (in thousands) to be retained from the previous OLDsyslog.log file. For example, to retain 20,000 lines from the previous OLDsyslog.log file along with the contents of the previous syslog.log in the present OLDsyslog.log, put PREV_OLDSYSLOG_LINES=20 in /etc/rc.config.d/syslogd. By default PREV_OLDSYSLOG_LINES is set to 0.

syslogd configures itself when it starts up and whenever it receives a hangup signal. Lines in the configuration file consist of a selector to determine the message priorities to which the line applies and an action. The action field is separated from the selector by one or more tabs.

Selectors are semicolon separated lists of priority specifiers. Each priority has a facility indicating the subsystem that generated the message, a dot, and a level indicating the severity of the message. Symbolic names can be used. An asterisk selects all facilities. All messages of the specified level or higher (greater severity) are selected. More than one facility can be selected, using commas to separate them. For example:

selects all facilities at the emerg level and the mail and daemon facilities at the crit level.

The known facilities and levels recognized by syslogd are those listed in syslog(3C) converted to lowercase without the leading LOG_. The additional facility mark has a message at priority LOG_INFO sent to it every 20 minutes (this can be changed with the -m flag). The mark facility is not enabled by a facility field containing an asterisk. The level none can be used to disable a particular facility. For example,

selects all messages except mail messages.

The second part of each line describes where the message is to be logged if this line is selected. There are four forms:

Blank lines and lines beginning with a # character are ignored.

For example, the configuration file:

logs all kernel messages and 20 minute marks onto the system console, all mail system messages to /var/adm/syslog/mail.log, and all messages at info and above, except mail messages, to the file /var/adm/syslog/syslog.log. Messages at alert and above are logged to the console and to the users root, eric, and kridle if they are logged in. emerg messages are written to all logged-in users' terminals, and forwarded to the host admin.

Only a superuser can invoke syslogd.

Notes

syslogd logs messages into a set of files. Once the size of a log file reaches 2 GB, syslogd stops logging to that file. You can configure the maximum size of syslogd log files by setting the variable LOG_SIZE in /etc/default/syslogd. The values of LOG_SIZE can be any positive integer greater than 2, representing the maximum size of the file in GB. When LOG_SIZE=NOLIMIT, syslogd uses the limit imposed by the file system on file size.

syslogd logs messages in a locale-independent fashion as a stream of bytes and will replace each newline character in the message with a blank space except for the last newline character. Applications using the services of syslogd can log messages in different locales. However, be careful when configuring syslogd so that messages from different locales do not get logged to the same log file.