.\" -*- nroff -*- .\" Copyright (c) 2018-2022 Joachim Wiberg .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .Dd August 1, 2022 .Dt LOGGER 1 .Os sysklogd .Sh NAME .Nm logger .Nd Send messages to system log daemon, or a log file .Sh SYNOPSIS .Nm .Op Fl 46bchiknsv .Op Fl d Ar SD .Op Fl f Ar FILE .Op Fl h Ar HOST .Op Fl H Ar HOSTNAME .Op Fl I Ar PID .Op Fl m Ar MSGID .Op Fl p Ar PRIO .Op Fl P Ar PORT .Op Fl r Ar SIZE:NUM .Op Fl t Ar TAG .Op Fl u Ar SOCK .Op Ar MESSAGE .Sh DESCRIPTIOMN .Nm can be used to log messages to a local or remote system log daemon, or a log file, from a UNIX shell, or script. The new .Xr syslogp 3 API is always used but .Nm syslogd is bypassed in the remote log daemon and local log file use-cases. The log file is also be automatically rotated. See below for log rotation options. .Pp Without a .Ar MESSAGE argument, .Nm waits for input on .Ar stdin , consuming all data until EOF. .Sh OPTIONS This program follows the usual UNIX command line syntax: .Bl -tag -width Ds .It Fl 4 Force .Nm to use IPv4 addresses only. .It Fl 6 Force .Nm to use IPv6 addresses only. .It Fl b Use RFC3164 (BSD) style format, default: RFC5424. .It Fl c Log to console .Ql ( LOG_CONS ) if .Fn syslog fails to send message to .Xr syslogd 8 . .It Fl d Ar SD Log this in the structured data (SD) field of an RFC5424 style log message. See .Fl m for caveats. Also, please note that .Ar sd has to be passed as one argument and will require careful quoting when used from the shell. .It Fl f Ar FILE Log file to write messages to, instead of syslog daemon. .Nm accepts .Fl f- as an alias for .Ar stdout . .It Fl H Ar hostname Set the hostname in the header of the message to specified value. If not specified, host part of .Xr gethostname 3 will be used. .It Fl h Ar host Send the message to the remote system .Ar host instead of logging it locally. .It Fl I Ar PID Like .Fl i , but uses .Ar PID . Useful when logging from shell scripts that send multiple messages. E.g., the following arguments might be a useful template: .Bd -literal -offset indent logger -t $(basename $0) -I $$ .Ed .It Fl i Log the process id of the logger process with each line .Ql ( LOG_PID ) . .It Fl k Log to kernel .Pa /dev/kmsg if .Pa /dev/log doesn't exist yet. Only works on Linux systems and only if .Fl u Ar SOCK and .Fl f Ar FILE are .Sy not used . When .Nm syslogd eventually starts, it will recognize these messages, due to not having kernel facility, and log them properly. Highly useful for userspace scripts and applications running before .Nm syslogd has started. E.g., mount helpers and similar. .It Fl m Ar MSGID The MSGID used for the message. Requires RFC5424 support in .Xr syslogd 8 for receiving the message and also for storing it properly in a log file or sending remote in correctly formatted RFC5424 style. .It Fl n Open log file immediately .Ql ( LOG_NDELAY ) . .It Fl P Ar port Send the message to the specified .Ar port number on a remote system, which can be specified as a service name or as a decimal number. The default is .Dq Li syslog . If an unknown service name is used, .Nm prints a warning and falls back to port 514. .It Fl p Ar PRIO Priority, numeric or in .Ar facility.severity pair format, default: .Nm user.notice . .It Fl r Ar SIZE:NUM Controls log file rotation. .Ar SIZE denotes number of bytes before rotating, default: 200 kB. .Ar NUM denotes number of rotated files to keep when logging to a file, default: 5. .It Fl s Log to stderr as well as the system log. .It Fl t Ar TAG Log using the specified tag, default: username. .It Fl u Ar SOCK Log to UNIX domain socket .Ar SOCK instead of the default .Pa /dev/log . .It Fl v Show program version. .It Ar MESSAGE Log message to write. Remember to use single/double quotes if calling .Nm from a shell prompt due to expansion the shell does. If no message is given .Nm will read from .Ar stdin until EOF. In this mode every new row (newline separated) is converted into an independent .Xr syslogp 3 call. .El .Sh EXAMPLES .Bd -unfilled -offset left logger -t dropbear -p auth.notice "Successful login for user 'admin' from 1.2.3.4" logger -t udhcpc -f /tmp/script.log "New lease 1.2.3.200 obtained for interface eth0" .Ed .Sh FILES .Bl -tag -width /dev/log -compact .It Ar FILE If a custom log file is selected, using .Fl f Ar FILE , then this file is opened and written to by .Nm . When log file rotation is enabled, using .Fl r Ar SIZE:NUM , .Nm creates .Pa FILE.1 FILE.2 FILE.3.gz etc. .It Pa /dev/log Socket used for communicating with .Xr syslogd 8 . When built on BSD .Pa /var/run/log is used. .El .Sh SEE ALSO .Xr syslogp 3 .Xr syslogd 8 .Sh AUTHORS .Nm was originally written by Joachim Wiberg to be a part of the .Xr finit 1 system monitor (PID 1), where it is called .Nm logit . It is included here to complement .Xr syslogd 8 and be extended upon in the sysklogd project. .Sh STANDARDS The .Nm command is expected to be IEEE Std 1003.2 ("POSIX.2") compatible, with extensions for RFC5424 from NetBSD and custom log file and log file rotation unique to the sysklogd project.