Updated: 2022/Sep/29

Please read Privacy Policy. It's for your privacy.

SYSLOGD(8)                  System Manager's Manual                 SYSLOGD(8)

     syslogd - log systems messages

     syslogd [-nrSsTUvX] [-B buffer_length] [-b bind_address] [-d [[~]what]]
             [-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]

     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 [[~]what]     Do not disassociate from the controlling terminal and
                      enable debugging to the standard output.  The optional
                      what argument is a number that selects which categories
                      of the debug messages are to be enabled.  A tilde (`~')
                      before what inverts its meaning so that all messages
                      except those selected by what are enabled.

     -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

     -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 which
                      syslogd 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

     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.

     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.

     /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.

     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.

     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.

NetBSD 10.99                   November 8, 2022                   NetBSD 10.99