dmesg (8)


       dmesg - print or control the kernel ring buffer


       dmesg [ -c ] [ -n level ] [ -s bufsize ]


       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.


       -c     Clear the ring buffer contents after printing.

              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.

              Set the level at which logging of messages is done to  the  con-
              sole.   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

              When both options are used, only the last option on the  command
              line will have an effect.




       Theodore Ts'o (