1DMESG(1)                    General Commands Manual                   DMESG(1)
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NAME

6       dmesg - print or control the kernel ring buffer
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SYNOPSIS

9       dmesg [-c] [-r] [-n level] [-s bufsize]
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DESCRIPTION

12       dmesg is used to examine or control the kernel ring buffer.
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14       The program helps users to print out their bootup messages.  Instead of
15       copying the messages by hand, the user need only:
16              dmesg > boot.messages
17       and mail the boot.messages file to whoever can debug their problem.
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OPTIONS

20       -c     Clear the ring buffer contents after printing.
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22       -r     Print the raw message buffer, i.e., don't strip  the  log  level
23              prefixes.
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25       -s bufsize
26              Use  a  buffer  of size bufsize to query the kernel ring buffer.
27              This is 16392 by default.  (The  default  kernel  syslog  buffer
28              size was 4096 at first, 8192 since 1.3.54, 16384 since 2.1.113.)
29              If you have set the kernel buffer to be larger than the  default
30              then this option can be used to view the entire buffer.
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32       -n level
33              Set  the  level at which logging of messages is done to the con‐
34              sole.  For example, -n 1 prevents  all  messages,  except  panic
35              messages, from appearing on the console.  All levels of messages
36              are still written to /proc/kmsg, so syslogd(8) can still be used
37              to  control  exactly  where kernel messages appear.  When the -n
38              option is used, dmesg will not print or clear  the  kernel  ring
39              buffer.
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41              When  both options are used, only the last option on the command
42              line will have an effect.
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SEE ALSO

45       syslogd(8)
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AVAILABILITY

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