DMESG(8)                                                 DMESG(8)

NAME
       dmesg - print or control the kernel ring buffer

SYNOPSIS
       dmesg [ -c ] [ -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  mes-
       sages.   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.

       -sbufsize
              use  a  buffer  of bufsize to query the kernel ring
              buffer.  This is 8196 by default (this matches  the
              default  kernel  syslog  buffer  size in 2.0.33 and
              2.1.103).  If you have set  the  kernel  buffer  to
              larger  than  the  default  then this option can be
              used to view the entire buffer.

       -nlevel
              set the level at which logging of messages is  done
              to  the  console.   For  example, -n 1 prevents all
              messages, expect 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)

AUTHOR
       Theodore Ts'o (tytso@athena.mit.edu)

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