Provided by: util-linux_2.20.1-1ubuntu3_i386 bug

NAME

       dmesg - print or control the kernel ring buffer

SYNOPSIS

       dmesg [options]

       dmesg --clear

       dmesg --read-clear [options]

       dmesg --console-level level

       dmesg --console-on

       dmesg --console-off

DESCRIPTION

       dmesg is used to examine or control the kernel ring buffer.

       The default action is to read all messages from kernel ring buffer.

OPTIONS

       The  --clear,  --read-clear, --console-on, --console-off and --console-
       level options are mutually exclusive.

       -C, --clear
              Clear the ring buffer.

       -c, --read-clear
              Clear the ring buffer contents after printing.

       -D, --console-off
              Disable printing messages to the console.

       -d, --show-delta
              Display the timestamp and time delta spent between messages.  If
              used together with --notime then only the time delta without the
              timestamp is printed.

       -E, --console-on
              Enable printing messages to the console.

       -f, --facility list
              Restrict output to defined (comma separated) list of facilities.
              For example

                dmesg --facility=daemon

              will  print messages from system daemons only. For all supported
              facilities see dmesg --help output.

       -h, --help
              Print a help text and exit.

       -k, --kernel
              Print kernel messages.

       -l, --level list
              Restrict output to defined (comma separated) list of levels. For
              example

                dmesg --level=err,warn

              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.

       -r, --raw
              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.

       -T, --ctime
              Print  human  readable  timestamps.  The  timestamp   could   be
              inaccurate!

              The  time  source  used for the logs is not updated after system
              SUSPEND/RESUME.

       -t, --notime
              Don't print kernel's timestampts.

       -u, --userspace
              Print userspace messages.

       -V, --version
              Output version information and exit.

       -x, --decode
              Decode facility and level (priority) number  to  human  readable
              prefixes.

SEE ALSO

       syslogd(8)

AUTHORS

       Karel Zak <kzak@redhat.com>
       Theodore Ts'o <tytso@athena.mit.edu>

AVAILABILITY

       The  dmesg  command  is part of the util-linux package and is available
       from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.