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 sys-
              log 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 messages,
              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.kernel.org/pub/linux/utils/util-
       linux-ng/.



                                                                                                                        DMESG(1)