DMESG(8) System Manager's Manual DMESG(8)NAME
dmesg - collect system diagnostic messages to form error log
/sbin/dmesg [ - ]
N.B.: Dmesg is obsoleted by syslogd(8) for maintenance of the system error log.
Dmesg looks in a system buffer for recently printed diagnostic messages and prints them on the standard output. The messages are those
printed or logged by the system when errors occur. If the - flag is given, then dmesg computes (incrementally) the new messages since the
last time it was run and places these on the standard output.
/usr/adm/msgbuf scratch file for memory of - option
SEE ALSO syslogd(8)4th Berkeley Distribution November 17, 1996 DMESG(8)
Check Out this Related Man Page
DMESG(1) User Commands DMESG(1)NAME
dmesg - print or control the kernel ring buffer
dmesg --read-clear [options]
dmesg --console-level level
dmesg is used to examine or control the kernel ring buffer.
The default action is to read all messages from kernel ring buffer.
The --clear, --read-clear, --console-on, --console-off and --console-level options are mutually exclusive.
Clear the ring buffer.
Clear the ring buffer contents after printing.
Disable printing messages to the console.
Display the timestamp and time delta spent between messages. If used together with --notime then only the time delta without the
timestamp is printed.
Enable printing messages to the console.
-f, --facility list
Restrict output to defined (comma separated) list of facilities. For example
will print messages from system daemons only. For all supported facilities see dmesg --help output.
Print a help text and exit.
Print kernel messages.
-l, --level list
Restrict output to defined (comma separated) list of levels. For example
will print error and warning messages only. For all supported levels see dmesg --help output.
-n, --console-level level
Set the level at which logging of messages is done to the console. The level is a level number or abbreviation of the level name.
For all supported levels see dmesg --help output.
For example, -n 1 or -n alert prevents all messages, except emergency (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.
Print the raw message buffer, i.e., don't strip the log level prefixes.
-s, --buffer-size size
Use a buffer of size 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.
Print human readable timestamps. The timestamp could be inaccurate!
The time source used for the logs is not updated after system SUSPEND/RESUME.
Don't print kernel's timestampts.
Print userspace messages.
Output version information and exit.
Decode facility and level (priority) number to human readable prefixes.
SEE ALSO syslogd(8)AUTHORS
Karel Zak <email@example.com>
Theodore Ts'o <firstname.lastname@example.org>
The dmesg command is part of the util-linux package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.
util-linux July 2011 DMESG(1)