1DMESG(8)                    System Manager's Manual                   DMESG(8)
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NAME

6       dmesg - print or control the kernel ring buffer
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SYNOPSIS

9       dmesg [ -c ] [ -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       -sbufsize
23              Use a buffer of size bufsize to query the  kernel  ring  buffer.
24              This  is  16392  by  default.  (The default kernel syslog buffer
25              size was 4096 at first, 8192 since 1.3.54, 16384 since 2.1.113.)
26              If  you have set the kernel buffer to be larger than the default
27              then this option can be used to view the entire buffer.
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29       -nlevel
30              Set the level at which logging of messages is done to  the  con‐
31              sole.   For  example,  -n  1 prevents all messages, expect panic
32              messages, from appearing on the console.  All levels of messages
33              are still written to /proc/kmsg, so syslogd(8) can still be used
34              to control exactly where kernel messages appear.   When  the  -n
35              option  is  used,  dmesg will not print or clear the kernel ring
36              buffer.
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38              When both options are used, only the last option on the  command
39              line will have an effect.
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SEE ALSO

42       syslogd(8)
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