freebsd-skq/sbin/dmesg/dmesg.8

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.\"     @(#)dmesg.8	8.1 (Berkeley) 6/5/93
.\" $FreeBSD$
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.Dd October 3, 2016
.Dt DMESG 8
.Os
.Sh NAME
.Nm dmesg
.Nd "display the system message buffer"
.Sh SYNOPSIS
.Nm
.Op Fl ac
.Op Fl M Ar core Op Fl N Ar system
.Sh DESCRIPTION
The
.Nm
utility displays the contents of the system message buffer.
If the
.Fl M
option is not specified, the buffer is read from the currently running kernel
via the
.Xr sysctl 3
interface.
Otherwise, the buffer is read from the specified core file,
using the name list from the specified kernel image (or from
the default image).
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl a
Show all data in the message buffer.
This includes any syslog records and
.Pa /dev/console
output.
.It Fl c
Clear the kernel buffer after printing.
.It Fl M
Extract values associated with the name list from the specified core.
.It Fl N
If
.Fl M
is also specified,
extract the name list from the specified system instead of the default,
which is the kernel image the system has booted from.
.El
.Sh FILES
.Bl -tag -width ".Pa /var/run/dmesg.boot" -compact
.It Pa /var/run/dmesg.boot
usually a snapshot of the buffer contents
taken soon after file systems are mounted
at startup time
.El
.Sh SEE ALSO
.Xr sysctl 3 ,
.Xr syslogd 8
.Sh HISTORY
The
.Nm
utility appeared in
.Bx 3 .