SYSLOG.CONF(5) File Formats Manual SYSLOG.CONF(5)

syslog.confsyslogd(8) configuration file

The syslog.conf file is the configuration file for the syslogd(8) program. It consists of lines with two fields: the selector field which specifies the types of messages and priorities to which the line applies, and an action field which specifies the action to be taken if a message syslogd receives matches the selection criteria. The selector field is separated from the action field by one or more tab characters.

The function are encoded as a facility, a period (``.''), and a level, with no intervening white-space. Both the facility and the level are case insensitive.

The facility describes the part of the system generating the message. Legacy facility names are: auth, authpriv, cron, daemon, kern, lpr, mail, mark, news, syslog, user, uucp and local0 through local7. These keywords (with the exception of mark) correspond to the similar “LOG_” values specified to the openlog(3) and syslog(3) library routines.

Apple System Log (ASL) messages, sent using the asl(3) library routines permit the facility name to be an arbitrary string, although users of the system are encouraged to use a “reverse ICANN” naming convention, for example “”. Since these facility names may contain dot characters, the names may be enclosed in either singe quote or double quote characters.

If facility is terminated by an asterisk (``*''), then facility names are matched using the prefix characters preceeding the asterisk. For example,


matches any facility with the prefix ``''. These wildcard facility names typically must be enclosed in single or double quotes characters.

The level describes the severity of the message, and is a keyword from the following ordered list (higher to lower): emerg, alert, crit, err, warning, notice, info and debug. These keywords correspond to the similar (LOG_) values specified to the syslog library routine.

See syslog(3) for a further descriptions of both the facility and level keywords and their significance.

If a received message matches the specified facility and is of the specified level , the action specified in the action field will be taken.

Multiple may be specified for a single action by separating them with semicolon (``;'') characters. It is important to note, however, that each selector can modify the ones preceding it.

Multiple facilities may be specified for a single level by separating them with comma (``,'') characters.

An asterisk (``*'') can be used to specify all facilities or all .

The special facility ``mark'' receives a message at priority ``info'' every 20 minutes (see syslogd(8)). This is not enabled by a facility field containing an asterisk.

The special level ``none'' disables a particular facility.

The action field of each line specifies the action to be taken when the selector field selects a message. There are four forms:

Blank lines and lines whose first non-blank character is a hash (``#'') character are ignored.

A configuration file might appear as follows:

# Log all kernel messages, authentication messages of
# level notice or higher and anything of level err or
# higher to the console.
# Don't log private authentication messages!
*.err;kern.*;auth.notice;authpriv.none	/dev/console

# Log anything (except mail) of level info or higher.
# Don't log private authentication messages!
*.info;mail.none;authpriv.none		/var/log/messages

# The authpriv file has restricted access.
authpriv.*						/var/log/secure

# Log all the mail messages in one place.
mail.*							/var/log/maillog

# Everybody gets emergency messages, plus log them on another
# machine.
*.emerg							*

# Root and Eric get alert and higher messages.
*.alert							root,eric

# Save mail and news errors of level err and higher in a
# special file.
uucp,news.crit						/var/log/spoolerr

The syslogd(8) configuration file.

The effects of multiple selectors are sometimes not intuitive. For example ``mail.crit,*.err'' will select ``mail'' facility messages at the level of ``err'' or higher, not at the level of ``crit'' or higher.

asl(3), syslog(3), syslogd(8)

The syslog.conf file appeared in 4.3BSD, along with syslogd(8).

June 9, 1993 macOS 14.4