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from: @(#)syslog.conf.5 8.1 (Berkeley) 6/9/93
$OpenBSD: syslog.conf.5,v 1.39 2019/01/13 11:07:47 schwarze Exp $
$NetBSD: syslog.conf.5,v 1.4 1996/01/02 17:41:46 perry Exp $
.Dd $Mdocdate: July 23 2018 $ .Dt SYSLOG.CONF 5 .Os .Sh NAME .Nm syslog.conf .Nd syslogd(8) configuration file .Sh DESCRIPTION The .Nm syslog.conf file is the configuration file for the .Xr syslogd 8 program. It consists of blocks of lines separated by .Em program specifications, with each line containing two fields: the .Em selector field which specifies the types of messages and priorities to which the line applies, and an .Em action field which specifies the action to be taken if a message .Xr syslogd 8 receives matches the selection criteria. The .Em selector field is separated from the .Em action field by one or more tab or space characters.
p The .Em selectors are encoded as a .Em facility , a period
q Ql . , and a .Em level , with no intervening whitespace. Both the .Em facility and the .Em level are case insensitive.
p The .Em facility describes the part of the system generating the message, and is one of the following keywords: auth, authpriv, cron, daemon, ftp, kern, lpr, mail, mark, news, syslog, user, uucp and local0 through local7. These keywords (with the exception of mark) correspond to the similar .Dq Dv LOG_ values specified to the .Xr openlog 3 and .Xr syslog 3 library routines.
p The .Em level describes the severity of the message, and is a keyword from the following ordered list (highest to lowest): emerg, alert, crit, err, warning, notice, info and debug. These keywords correspond to the similar
q Dv LOG_ values specified to the .Xr syslog 3 library routine.
p Each block of lines is separated from the previous block by a tag. The tag is a line beginning with .Em !prog and each block will be associated with calls to syslog from that specific program (matched using .Xr glob 7 rules). When a message matches multiple blocks, the action of each matching block is taken. If no tag is specified at the beginning of the file, every line is checked for a match and acted upon
q at least until a tag is found .
p .Em !!prog causes the subsequent block to abort evaluation when a message matches, ensuring that only a single set of actions is taken. .Em !*\& can be used to ensure that any ensuing blocks are further evaluated (i.e. cancelling the effect of a .Em !prog or .Em !!prog ) .
p Blocks starting with .Em +host or .Em ++host or .Em +* work the same way as their .Em prog counterparts, but they match on the hostname instead of the program name.
p See .Xr syslog 3 for further descriptions of both the .Em facility and .Em level keywords and their significance. It's recommended that selections be made on .Em facility rather than .Em program , since the latter can easily vary in a networked environment. In some cases, though, an appropriate .Em facility simply doesn't exist.
p If a received message matches the specified .Em facility and is of the specified .Em level
q Em or a higher level , and the first word in the message after the date matches the .Em program , the action specified in the .Em action field will be taken. In this context, .Xr ascii 7 letters, digits, hyphens
q Sq - , periods
q Sq . , and underscores
q Sq _ can be contained in a word; other bytes end the word.
p Multiple .Em selectors may be specified for a single .Em action by separating them with semicolon
q Ql ; characters. It is important to note, however, that each .Em selector can modify the ones preceding it.
p Multiple .Em facilities may be specified for a single .Em level by separating them with comma
q Ql , characters.
p An asterisk
q Ql * can be used to specify all .Em facilities , all .Em levels or all .Em programs .
p The special .Em facility .Dq mark receives a message at priority .Dq info every 20 minutes (see .Xr syslogd 8 ) . This is not enabled by a .Em facility field containing an asterisk.
p The special .Em level .Dq none disables a particular .Em facility .
p The .Em action field of each line specifies the action to be taken when the .Em selector field selects a message. There are six forms: l -bullet t A pathname (beginning with a leading slash). Selected messages are appended to the file. t A pipe to another program (beginning with a leading pipe symbol). The given program is started and presented the selected messages on its standard input. If the program exits, .Xr syslogd 8 tries to restart it. t A hostname (preceded by an at
q Ql @ sign). Selected messages are forwarded to the .Xr syslogd 8 program on the named host. A port number may be specified using the .Ar host:port syntax. This is optional for UDP and TLS. There is no well-known port for syslog over TCP, so in this case it is mandatory to specify the port. IPv6 addresses can be used by surrounding the address portion with square brackets
o .Ql [\& and .Ql ]\&
c . A prefix udp4:// or udp6:// in front of the hostname and after the at sign will force IPv4 or IPv6 addresses for UDP transport. The prefixes tcp[46]:// or tls[46]:// send messages over TCP or TLS, respectively, with an optional IP version 4 or 6. t A comma separated list of users. Selected messages are written to those users if they are logged in. t An asterisk. Selected messages are written to all logged-in users. t A colon, followed by a memory buffer size
q in kilobytes , followed by another colon, followed by a buffer name. Selected messages are written to an in-memory buffer that may be read using .Xr syslogc 8 . Memory buffered logging is useful to provide access to log data on devices that lack local storage (e.g. diskless workstations or routers). The largest allowed buffer size is 256kb. .El
p Blank lines and lines whose first non-blank character is a hash
q Ql # character are ignored. .Sh FILES l -tag -width /etc/syslog.conf -compact t Pa /etc/syslog.conf The .Xr syslogd 8 configuration file. .El .Sh EXAMPLES A configuration file might appear as follows: d -literal # Log info (and higher) messages from spamd only to # a dedicated file, discarding debug messages. # Matching messages abort evaluation of further rules. !!spamd daemon.info /var/log/spamd daemon.debug /dev/null !* # 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 * *.emerg @arpa.berkeley.edu # Root and Eric get alert and higher messages. *.alert root,eric # Log everything coming from host bastion to a separate file. ++bastion *.* /var/log/bastion +* # Save mail and news errors of level err and higher in a # special file. mail,news.err /var/log/spoolerr # Save ftpd transactions along with mail and news. !ftpd *.* /var/log/spoolerr # Keep a copy of all logging in a 32k memory buffer named "debug". *.debug :32:debug # Store notices and authpriv messages in a 64k buffer named "important". *.notice,authpriv.* :64:important # Feed everything to logsurfer. *.* |/usr/local/sbin/logsurfer .Ed .Sh SEE ALSO .Xr syslog 3 , .Xr syslogc 8 , .Xr syslogd 8 .Sh HISTORY The .Nm file appeared in x 4.3 , along with .Xr syslogd 8 .
p Historic versions of .Xr syslogd 8 did not support space-delimited fields. .Sh BUGS The effects of multiple selectors are sometimes not intuitive. For example .Dq mail.crit;*.err will select .Dq mail facility messages at the level of .Dq err or higher, not at the level of .Dq crit or higher.