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28 .\" @(#)syslog.conf.5 8.1 (Berkeley) 6/9/93
41 file is the configuration file for the
45 blocks of lines separated by
49 .Em property-based filter
50 specifications (separations appear alone on their lines),
51 with each line containing two fields: the
53 field which specifies the types of messages and priorities to which the
56 field which specifies the action to be taken if a message
58 receives matches the selection criteria.
61 field is separated from the
63 field by one or more tab characters or spaces.
67 keyword can be used to include all files with names ending in '.conf' and not
68 beginning with a '.' contained in the directory following the keyword.
69 This keyword can only be used in the first level configuration file.
71 Note that if you use spaces as separators, your
73 might be incompatible with other Unices or Unix-like systems.
74 This functionality was added for ease of configuration
75 (e.g.,\& it is possible to cut-and-paste into
77 and to avoid possible mistakes.
78 This change however preserves
79 backwards compatibility with the old style of
81 (i.e., tab characters only).
89 an optional set of comparison flags
90 .Pq Oo \&! Oc Op <=> ,
93 with no intervening white-space.
102 describes the part of the system generating the message, and is one of
103 the following keywords:
104 .Cm auth , authpriv , console , cron , daemon , ftp , kern , lpr ,
105 .Cm mail , mark , news , ntp , security , syslog , user , uucp ,
110 These keywords (with the exception of mark) correspond to
113 values specified to the
121 may be used to specify exactly what is logged.
122 The default comparison is
126 which means that messages from the specified
128 list, and of a priority
129 level equal to or greater than
132 Comparison flags beginning with
134 will have their logical sense inverted.
137 means all levels except info and
139 has the same meaning as
144 describes the severity of the message, and is a keyword from the
145 following ordered list (higher to lower):
146 .Cm emerg , alert , crit , err , warning , notice , info
149 These keywords correspond to
152 values specified to the
156 Each block of lines is separated from the previous block by a
160 .Em property-based filter
162 A block will only log messages corresponding to the most recent
166 .Em property-based filter
167 specifications given.
168 Thus, with a block which selects
172 directly followed by a block that selects messages from the
175 the second block will only log messages
182 specification is a line beginning with
186 (the former is for compatibility with the previous syslogd, if one is sharing
189 and the following blocks will be associated with calls to
191 from that specific program.
196 will also match any message logged by the kernel with the prefix
202 specification works just like the previous one,
207 specification will match any message but the ones from that
209 Multiple programs may be listed, separated by commas:
211 matches messages from either program, while
213 matches all messages but those from
220 specification of the form
224 means the following blocks will be applied to messages
225 received from the specified hostname.
232 causes the following blocks to be applied to messages
233 from any host but the one specified.
234 If the hostname is given as
236 the local hostname will be used.
237 As for program specifications, multiple comma-separated
238 values may be specified for hostname specifications.
241 .Em property-based filter
242 specification is a line beginning with
246 and the following blocks will be applied only when filter value
247 matches given filter propertie's value.
249 .Sx PROPERTY-BASED FILTERS
250 section for more details.
256 .Em property-based filter
257 specification may be reset by giving
263 for further descriptions of both the
267 keywords and their significance.
268 It is preferred that selections be made on
272 since the latter can easily vary in a networked environment.
274 though, an appropriate
276 simply does not exist.
278 If a received message matches the specified
280 and is of the specified
282 .Em (or a higher level) ,
283 and the first word in the message after the date matches the
285 the action specified in the
291 may be specified for a single
293 by separating them with semicolon
296 It is important to note, however, that each
298 can modify the ones preceding it.
302 may be specified for a single
304 by separating them with comma
310 can be used to specify all
320 receives a message at priority
325 This is not enabled by a
327 field containing an asterisk.
332 disables a particular
337 field of each line specifies the action to be taken when the
339 field selects a message.
340 There are five forms:
343 A pathname (beginning with a leading slash).
344 Selected messages are appended to the file.
346 To ensure that kernel messages are written to disk promptly,
350 after writing messages from the kernel.
351 Other messages are not synced explicitly.
352 You may prefix a pathname with the minus sign,
354 to forego syncing the specified file after every kernel message.
355 Note that you might lose information if the system crashes
356 immediately following a write attempt.
357 Nevertheless, using the
359 option may improve performance,
360 especially if the kernel is logging many messages.
362 A hostname (preceded by an at
365 Selected messages are forwarded to the
367 program on the named host.
368 If a port number is added after a colon
370 then that port will be used as the destination port
371 rather than the usual syslog port.
372 IPv6 addresses can be used
373 by surrounding the address portion with
381 A comma separated list of users.
382 Selected messages are written to those users
383 if they are logged in.
386 Selected messages are written to all logged-in users.
390 followed by a command to pipe the selected
392 The command is passed to
394 for evaluation, so usual shell metacharacters or input/output
395 redirection can occur.
396 (Note however that redirecting
398 buffered output from the invoked command can cause additional delays,
399 or even lost output data in case a logging subprocess exited with a
401 The command itself runs with
410 will close the pipe to the process.
411 If the process did not exit
412 voluntarily, it will be sent a
414 signal after a grace period of up to 60 seconds.
416 The command will only be started once data arrives that should be piped
418 If it exited later, it will be restarted as necessary.
420 is desired that the subprocess should get exactly one line of input only
421 (which can be very resource-consuming if there are a lot of messages
422 flowing quickly), this can be achieved by exiting after just one line of
424 If necessary, a script wrapper can be written to this effect.
426 Unless the command is a full pipeline, it is probably useful to
427 start the command with
429 so that the invoking shell process does not wait for the command to
431 Warning: the process is started under the UID invoking
433 normally the superuser.
436 Blank lines and lines whose first non-blank character is a hash
438 character are ignored.
441 is placed in the middle of the line, the
443 character and the rest of the line after it is ignored.
444 To prevent special meaning, the
446 character may be escaped with
448 in this case preceding
452 is treated as an ordinary character.
453 .Sh PROPERTY-BASED FILTERS
456 specifications performs exact match filtering against explicit field only.
457 .Em Property-based filters
458 feature substring and regular expressions (see
460 matching against various message attributes.
461 Filter specification starts with
465 followed by three comma-separated fields
466 .Em property , operator , \&"value\&" .
467 Value must be double-quoted.
468 A double quote and backslash must be escaped by a backslash.
472 are supported as test value:
477 - body of the message received.
480 - program name sent the message
483 - hostname of message's originator
486 - an alias for hostname
489 Operator specifies a comparison function between
491 value against filter's value.
497 - true if filter value is found as a substring of
501 - true if filter value is equal to
505 - true if property starts with filter value
508 - true if property matches basic regular expression defined in filter value
511 - true if property matches extended regular expression defined in filter value
514 Operator may be prefixed by
519 - to invert compare logic
522 - to make comparison function case insensitive
524 .Sh IMPLEMENTATION NOTES
527 facility is usually reserved for messages
528 generated by the local kernel.
529 Other messages logged with facility
531 are usually translated to facility
533 This translation can be disabled;
538 .Bl -tag -width /etc/syslog.conf -compact
539 .It Pa /etc/syslog.conf
544 A configuration file might appear as follows:
546 # Log all kernel messages, authentication messages of
547 # level notice or higher, and anything of level err or
548 # higher to the console.
549 # Do not log private authentication messages!
550 *.err;kern.*;auth.notice;authpriv.none;mail.crit /dev/console
552 # Log anything (except mail) of level info or higher.
553 # Do not log private authentication messages!
554 *.info;mail.none;authpriv.none /var/log/messages
556 # Log daemon messages at debug level only
557 daemon.=debug /var/log/daemon.debug
559 # The authpriv file has restricted access.
560 authpriv.* /var/log/secure
562 # Log all the mail messages in one place.
563 mail.* /var/log/maillog
565 # Everybody gets emergency messages, plus log them on another
568 *.emerg @arpa.berkeley.edu
570 # Root and Eric get alert and higher messages.
573 # Save mail and news errors of level err and higher in a
575 uucp,news.crit /var/log/spoolerr
577 # Pipe all authentication messages to a filter.
578 auth.* |exec /usr/local/sbin/authfilter
580 # Log all security messages to a separate file.
581 security.* /var/log/security
583 # Log all writes to /dev/console to a separate file.
584 console.* /var/log/console.log
586 # Save ftpd transactions along with mail and news
588 *.* /var/log/spoolerr
590 # Log ipfw messages without syncing after every message.
594 # Log ipfw messages with "Deny" in the message body.
595 :msg, contains, ".*Deny.*"
596 *.* /var/log/ipfw.deny
598 # Reset program name filtering
601 # Log messages from bird or bird6 into one file
602 :programname, regex, "^bird6?$"
603 *.* /var/log/bird-all.log
605 # Log messages from servers in racks 10-19 in multiple locations, case insensitive
606 :hostname, icase_ereregex, "^server-(dcA|podB|cdn)-rack1[0-9]{2}\\..*"
607 *.* /var/log/racks10..19.log
613 The effects of multiple
615 are sometimes not intuitive.
620 facility messages at the level of
622 or higher, not at the level of
626 In networked environments, note that not all operating systems
627 implement the same set of facilities.
629 authpriv, cron, ftp, and ntp that are known to this implementation
630 might be absent on the target system.
631 Even worse, DEC UNIX uses
632 facility number 10 (which is authpriv in this implementation) to
633 log events for their AdvFS file system.