man dmesgDMESG(8)NAMEdmesg – print or control the kernel ring bufferSYNOPSISdmesg [ -c ] [ -n level ] [ -s bufsize ]DESCRIPTIONdmesg is used to examine or control the kernel ring buffer.The program helps users to print out their bootup messages. Instead of copying the mes-sages by hand, the user need only:dmesg > boot.messagesand mail the boot.messages file to whoever can debug their problem.OPTIONS-c Clear the ring buffer contents after printing.-sbufsizeUse a buffer of size bufsize to query the kernel ring buffer. This is 16392 bydefault. (The default kernel syslog buffer size was 4096 at first, 8192 since1.3.54, 16384 since 2.1.113.) If you have set the kernel buffer to be larger thanthe default then this option can be used to view the entire buffer.-nlevelSet the level at which logging of messages is done to the console. For example, -n1 prevents all messages, expect panic messages, from appearing on the console. Alllevels of messages are still written to /proc/kmsg, so syslogd(8) can still be usedto control exactly where kernel messages appear. When the -n option is used, dmesgwill not print or clear the kernel ring buffer.When both options are used, only the last option on the command line will have aneffect.SEE ALSOsyslogd(8)AUTHORTheodore Ts?o (tytso@athena.mit.edu)DMESG(8)~
