NAME
syslogd
—
log systems messages
SYNOPSIS
syslogd |
[-dnrSsTUvX ] [-B
buffer_length] [-b
bind_address] [-f
config_file] [-g
group] [-m
mark_interval] [-o
output_format] [-P
file_list] [-p
log_socket [-p
log_socket2 ...]] [-t
chroot_dir] [-u
user] |
DESCRIPTION
syslogd
reads and logs messages to the system console,
log files, other machines and/or users as specified by its configuration file.
The options are as follows:
-B
buffer_length- Sets the receiving buffer length. The default is 16384 bytes. If syslogd
reports buffer overflow, this needs increasing. If you don't care about it
being reported, see the
-X
option. -b
bind_address- Specify one specific IP address or hostname to bind to. If a hostname is specified, the IPv4 or IPv6 address which corresponds to it is used.
-d
- Enable debugging to the standard output, and do not disassociate from the controlling terminal.
-f
config_file- Specify the pathname of an alternative configuration file; the default is /etc/syslog.conf.
-g
group- Set GID to group after the sockets and log files have been opened.
-m
mark_interval- Select the number of minutes between ``mark'' messages; the default is 20 minutes.
-n
- Do not perform hostname lookups; report only numeric addresses.
-o
output_format- Select output message format.
- bsd, rfc3164
- traditional BSD Syslog format (default)
- syslog, rfc5424
- new syslog-protocol format
-P
- Specify the pathname of a file containing a list of sockets to be created. The format of the file is simply one socket per line.
-p
log_socket- Specify the pathname of a log socket. Multiple
-p
options create multiple log sockets. If no-p
arguments are given, the default socket of /var/run/log is used. -r
- Disable the compression of repeated instances of the same line into a single line of the form “last message repeated N times”.
-S
- Sync kernel messages to disk immediately.
-s
- Select “secure” mode, in which
syslogd
does not listen on a UDP socket but only communicates over a UNIX domain socket. This is valuable when the machine on whichsyslogd
runs is subject to attack over the network and it is desired that the machine be protected from attempts to remotely fill logs and similar attacks. -T
- Always use the local time and date for messages received from the network, instead of the timestamp field supplied in the message by the remote host. This is useful if some of the originating hosts can't keep time properly or are unable to generate a correct timestamp.
-t
chroot_dir- chroot(2) to chroot_dir after the sockets and log files have been opened.
-U
- Unique priority logging. Only log messages at the priority specified by the selector in the configuration file. Without this option, messages at the specified priority or higher are logged. This option changes the default priority comparison from ‘>=’ to ‘=’.
-u
user- Set UID to user after the sockets and log files have been opened.
-v
- Verbose logging. If specified once, the numeric facility and priority are logged with each locally-written message. If specified more than once, the names of the facility and priority are logged with each locally-written message.
-X
- Disable logging of buffer overflow.
syslogd
reads its configuration file when
it starts up and whenever it receives a hangup signal. For information on
the format of the configuration file, see
syslog.conf(5).
syslogd
reads messages from the
UNIX domain socket
/var/run/log, from an Internet domain socket
specified in /etc/services, and from the special
device /dev/klog (to read kernel messages).
syslogd
creates the file
/var/run/syslogd.pid, and stores its process id
there. This can be used to kill or reconfigure
syslogd
.
By using multiple -p
options, one can set
up many chroot environments by passing the pathname to the log socket
(/var/run/log) in each chroot area to
syslogd
. For example:
syslogd -p /var/run/log -p
/web/var/run/log -p /ftp/var/run/log
Note: the normal log socket must now also be passed to
syslogd
.
The logged message includes the date, time, and hostname (or pathname of the log socket). Commonly, the program name and the process id is included.
The date and time are taken from the received message. If the
format of the timestamp field is incorrect, time obtained from the local
host is used instead. This can be overridden by the
-T
flag.
Accesses from UDP socket can be filtered by libwrap configuration
files, like /etc/hosts.deny. Specify
“syslogd
” in
daemon_list portion of the configuration files. Refer
to hosts_access(5) for details.
SYSLOG PROTOCOL NOTES
syslogd
accepts messages in traditional
BSD Syslog or in newer Syslog Protocol format. See RFC 3164 (BSD Syslog) and
RFC 5424 (Syslog Protocol) for detailed description of the message format.
Messages from the local kernel that are not tagged with a priority code
receive the default facility LOG_KERN
and priority
LOG_NOTICE
. All other untagged messages receive the
default facility LOG_USER
and priority
LOG_NOTICE
.
FILES
- /etc/syslog.conf
- The configuration file.
- /var/run/syslogd.pid
- The process id of current
syslogd
. - /var/run/log
- Name of the UNIX domain datagram log socket.
- /dev/klog
- The kernel log device.
SEE ALSO
logger(1), syslog(3), services(5), syslog.conf(5), newsyslog(8)
The BSD syslog Protocol, RFC, 3164, August 2001.
The Syslog Protocol, RFC, 5424, March 2009.
HISTORY
The syslogd
command appeared in
4.3BSD. Support for multiple log sockets appeared in
NetBSD 1.4. libwrap support appeared in
NetBSD 1.6. Support for RFC 5424, TLS encryption and
authentication, signed messages appeared in NetBSD
6.0.