Dmesg - Display or control the kernel ring buffer - show bootup messages
Usage
Flags
Options:
-C, --clear clear the kernel ring buffer
-c, --read-clear read and clear all messages
-D, --console-off disable printing messages to console
-E, --console-on enable printing messages to console
-F, --file <file> use the file instead of the kernel log buffer
-f, --facility <list> restrict output to defined facilities
-H, --human human readable output
-k, --kernel display kernel messages
-L, --color[=<when>] colorize messages (auto, always or never)
colors are enabled by default
-l, --level <list> restrict output to defined levels
-n, --console-level <level> set level of messages printed to console
-P, --nopager do not pipe output into a pager
-p, --force-prefix force timestamp output on each line of multi-line messages
-r, --raw print the raw message buffer
-S, --syslog force to use syslog(2) rather than /dev/kmsg
-s, --buffer-size <size> buffer size to query the kernel ring buffer
-u, --userspace display userspace messages
-w, --follow wait for new messages
-x, --decode decode facility and level to readable string
-d, --show-delta show time delta between printed messages
-e, --reltime show local time and time delta in readable format
-T, --ctime show human-readable timestamp (may be inaccurate!)
-t, --notime don't show any timestamp with messages
--time-format <format> show timestamp using the given format:
[delta|reltime|ctime|notime|iso]
Suspending/resume will make ctime and iso timestamps inaccurate.
-h, --help display this help
-V, --version display version
Supported log facilities:
kern - kernel messages
user - random user-level messages
mail - mail system
daemon - system daemons
auth - security/authorization messages
syslog - messages generated internally by syslogd
lpr - line printer subsystem
news - network news subsystem
Supported log levels (priorities):
emerg - system is unusable
alert - action must be taken immediately
crit - critical conditions
err - error conditions
warn - warning conditions
notice - normal but significant condition
info - informational
debug - debug-level messages
For more details see dmesg(1).
Examples
dmesg
[ 0.000000] microcode: microcode updated early to revision 0xd6, date = 2020-04-27
[ 0.000000] Linux version 5.4.0-7634-generic (buildd@lcy01-amd64-029) (gcc version 9.3.0 (Ubuntu 9.3.0-10ubuntu2)) #38~1596560323~20.04~7719dbd-Ubuntu SMP Tue Aug 4 19:12:34 UTC 2 (Ubuntu 5.4.0-7634.38~1596560323~20.04~7719dbd-generic 5.4.41)
[ 0.000000] Command line: initrd=\EFI\Pop_OS-5d9b752f-4284-420f-98f4-ce080478be72\initrd.img root=UUID=5d9b752f-4284-420f-98f4-ce080478be72 ro quiet loglevel=0 systemd.show_status=false splash
[ 0.000000] KERNEL supported cpus:
[ 0.000000] Intel GenuineIntel
[ 0.000000] AMD AuthenticAMD
[ 0.000000] Hygon HygonGenuine
[ 0.000000] Centaur CentaurHauls
[ 0.000000] zhaoxin Shanghai
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x001: 'x87 floating point registers'
[...]
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