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DMESG(1)                                                              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 mes-
              sages, 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-ng   package   and   is   available   from   ftp://ftp.ker-
       nel.org/pub/linux/utils/util-linux-ng/.



                                                                      DMESG(1)