freebsd man page for dmesg

DMESG(8)						    BSD System Manager's Manual 						  DMESG(8)

NAME
     dmesg -- display the system message buffer

SYNOPSIS
     dmesg [-ac] [-M core [-N system]]

DESCRIPTION
     The dmesg utility displays the contents of the system message buffer.  If the -M option is not specified, the buffer is read from the cur-
     rently running kernel via the 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).

     The options are as follows:

     -a      Show all data in the message buffer.  This includes any syslog records and /dev/console output.

     -c      Clear the kernel buffer after printing.

     -M      Extract values associated with the name list from the specified core.

     -N      If -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.

FILES
     /var/run/dmesg.boot  usually a snapshot of the buffer contents taken soon after file systems are mounted at startup time

SEE ALSO
     sysctl(3), syslogd(8)

HISTORY
     The dmesg utility appeared in 4.0BSD.

BSD
								    May 9, 2013 							       BSD