syslog.conf —
configuration file for
syslogd(8)
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 or space characters. A rule can be split in several lines if all lines
except the last are terminated with a backslash ("
The
Selectors 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, and is one of the following keywords: 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.
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 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 (or a higher
level), the action specified in the
action
field will be taken.
Multiple
selectors 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
levels.
By default, a
level applies to all messages with
the same or higher
level. The equal
("=") character can be prepended to a
level to restrict this line of the configuration
file to messages with the very same
level.
An exclamation mark ("!") prepended to a
level or the asterisk means that this line of the
configuration file does
not apply to the
specified level (and higher ones). In conjunction with the equal sign, you can
exclude single
levels as well.
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 five forms:
- A pathname (beginning with a leading slash). Selected
messages are appended to the file.
You may prepend a minus ("-") to the path to omit syncing the file
after each message log. This can cause data loss at system crashes, but
increases performance for programs which use logging extensively.
- A named pipe (fifo), beginning with a vertical bar
("|") followed by a pathname. The pipe must be created with
mkfifo(8) before syslogd reads its
configuration file. This feature is especially useful fo debugging.
- A hostname (preceded by an at ("@") sign).
Selected messages are forwarded to the
syslogd program on the named host.
- A comma separated list of users. Selected messages are
written to those users if they are logged in.
- An asterisk. Selected messages are written to all
logged-in users.
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 *
*.emerg @arpa.berkeley.edu
# 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
- /etc/syslog.conf
- 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.
syslog(3),
syslogd(8)