1.\" Copyright (c) 1980, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgment: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)dmesg.8 8.1 (Berkeley) 6/5/93 33.\" $FreeBSD: src/sbin/dmesg/dmesg.8,v 1.5.2.5 2002/08/21 18:58:17 trhodes Exp $ 34.\" 35.Dd May 10, 2013 36.Dt DMESG 8 37.Os 38.Sh NAME 39.Nm dmesg 40.Nd "display the system message buffer" 41.Sh SYNOPSIS 42.Nm 43.Op Fl a 44.Op Fl c 45.Op Fl f 46.Op Fl M Ar core 47.Op Fl N Ar system 48.Sh DESCRIPTION 49The 50.Nm 51utility displays the contents of the system message buffer. 52If neither the 53.Fl N 54nor the 55.Fl M 56option is specified, the buffer is read from the currently running kernel 57via the 58.Xr sysctl 3 59interface. 60Otherwise, the buffer is read from the specified core file (or from the 61default one), using the name list from the specified kernel image (or from 62the default image). 63.Pp 64The options are as follows: 65.Bl -tag -width indent 66.It Fl a 67Show all data in the message buffer. 68This includes any syslog records and 69.Pa /dev/console 70output. 71.It Fl c 72Clear the kernel buffer after printing. 73.It Fl f 74After the initial message buffer dump 75.Nm 76monitors the kernel for additional data and displays it as it arrives. 77.Nm 78will not terminate until killed in this mode. 79.It Fl M 80Extract values associated with the name list from the specified core 81instead of the default 82.Pa /dev/kmem . 83.It Fl N 84Extract the name list from the specified system instead of the default, 85which is the kernel image the system has booted from. 86.El 87.Sh FILES 88.Bl -tag -width ".Pa /var/run/dmesg.boot" -compact 89.It Pa /var/run/dmesg.boot 90usually a snapshot of the buffer contents 91taken soon after file systems are mounted 92at startup time 93.El 94.Sh SEE ALSO 95.Xr sysctl 3 , 96.Xr syslogd 8 97.Sh HISTORY 98The 99.Nm 100utility appeared in 101.Bx 4.0 . 102