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dmesg(8) [freebsd man page]

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

Check Out this Related Man Page

DMESG(1)						      General Commands Manual							  DMESG(1)

NAME
dmesg - print or control the kernel ring buffer SYNOPSIS
dmesg [-c] [-r] [-n level] [-s bufsize] DESCRIPTION
dmesg is used to examine or control the kernel ring buffer. The program helps users to print out their bootup messages. Instead of copying the messages by hand, the user need only: dmesg > boot.messages and mail the boot.messages file to whoever can debug their problem. OPTIONS
-c Clear the ring buffer contents after printing. -r Print the raw message buffer, i.e., don't strip the log level prefixes. -s bufsize Use a buffer of size bufsize to query the kernel ring buffer. This is 16392 by default. (The default kernel syslog buffer size was 4096 at first, 8192 since 1.3.54, 16384 since 2.1.113.) If you have set the kernel buffer to be larger than the default then this option can be used to view the entire buffer. -n level Set the level at which logging of messages is done to the console. For example, -n 1 prevents all messages, except panic messages, from appearing on the console. All levels of messages are still written to /proc/kmsg, so syslogd(8) can still be used to control exactly where kernel messages appear. When the -n option is used, dmesg will not print or clear the kernel ring buffer. When both options are used, only the last option on the command line will have an effect. SEE ALSO
syslogd(8) AVAILABILITY
The dmesg command is part of the util-linux package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/. DMESG(1)

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