1.\" $NetBSD: dmesg.8,v 1.21 2018/04/14 01:34:47 kre Exp $ 2.\" 3.\" Copyright (c) 1980, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)dmesg.8 8.1 (Berkeley) 6/5/93 31.\" 32.Dd April 10, 2018 33.Dt DMESG 8 34.Os 35.Sh NAME 36.Nm dmesg 37.Nd display the system message buffer 38.Sh SYNOPSIS 39.Nm 40.Op Fl dTt 41.Op Fl M Ar core 42.Op Fl N Ar system 43.Sh DESCRIPTION 44.Nm 45displays the contents of the system message buffer. 46.Pp 47The options are as follows: 48.Bl -tag -width Ds 49.It Fl d 50Show the timestamp deltas. 51Used together with 52.Fl t 53only the deltas are shown. 54.It Fl M 55Extract values associated with the name list from the specified core 56instead of the default ``/dev/mem''. 57.It Fl N 58Extract the name list from the specified system instead of the default 59``/netbsd''. 60.It Fl T 61Format uptime timestamps in a human readable form (using 62.Xr ctime 3 ) . 63.It Fl t 64Quiet printing, don't print timestamps. 65.El 66.Pp 67The system message buffer is a circular buffer of a fixed size. 68If the buffer has been filled, the first line of the 69.Nm 70output may not be complete. 71The size of the message buffer is configurable at compile-time on 72most systems with the 73.Dv MSGBUFSIZE 74kernel option. 75Look for 76.Dv MSGBUFSIZE 77in 78.Xr options 4 79for details. 80.Sh FILES 81.Bl -tag -width /var/run/dmesg.boot -compact 82.It Pa /var/run/dmesg.boot 83copy of dmesg at the time of last boot. 84.El 85.Sh SEE ALSO 86.Xr options 4 , 87.Xr syslogd 8 88.Sh HISTORY 89The 90.Nm 91command appeared in 92.Bx 3.0 . 93