71 lines
1.8 KiB
Groff
71 lines
1.8 KiB
Groff
.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
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.\" May be distributed under the GNU General Public License
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.TH DMESG 1
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.SH NAME
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dmesg \- print or control the kernel ring buffer
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.SH SYNOPSIS
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.B dmesg
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.RB [ \-c ]
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.RB [ \-r ]
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.RB [ \-n
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.IR level ]
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.RB [ \-s
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.IR bufsize ]
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.SH DESCRIPTION
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.B dmesg
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is used to examine or control the kernel ring buffer.
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The program helps users to print out their bootup messages. Instead of
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copying the messages by hand, the user need only:
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.RS
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dmesg > boot.messages
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.RE
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and mail the
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.I boot.messages
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file to whoever can debug their problem.
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.SH OPTIONS
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.TP
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.B \-c
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Clear the ring buffer contents after printing.
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.TP
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.B \-r
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Print the raw message buffer, i.e., don't strip the log level prefixes.
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.TP
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.BI \-s " bufsize"
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Use a buffer of size
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.I bufsize
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to query the kernel ring buffer. This is 16392 by default.
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(The default kernel syslog buffer size was 4096
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at first, 8192 since 1.3.54, 16384 since 2.1.113.)
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If you have set the kernel buffer to be larger than the default
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then this option can be used to view the entire buffer.
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.TP
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.BI \-n " level"
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Set the
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.I level
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at which logging of messages is done to the console. For example,
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.B \-n 1
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prevents all messages, except panic messages, from appearing on the
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console. All levels of messages are still written to
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.IR /proc/kmsg ,
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so
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.BR syslogd (8)
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can still be used to control exactly where kernel messages appear. When
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the
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.B \-n
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option is used,
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.B dmesg
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will
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.I not
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print or clear the kernel ring buffer.
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When both options are used, only the last option on the command line will
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have an effect.
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.SH SEE ALSO
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.BR syslogd (8)
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.\" .SH AUTHOR
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.\" Theodore Ts'o (tytso@athena.mit.edu)
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.SH AVAILABILITY
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The dmesg command is part of the util-linux-ng package and is available from
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ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.
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