dmesg – Print or Control the kernel ring buffer
dmesg is used to examine or control the kernel ring buffer. The program helps users to print out their boot-up messages.
$ dmesg — Print the kernel boot-up messages.
$ dmesg > boot.mesg — Redirect the out to file.
# dmesg -c — Clear the ring buffer after printing.
# dmesg -s4096 — Set the kernel ring buffer size.
# dmesg -n1 — Set the level at which logging of messages is done to the console.
1 — Action must be taken immediately
2 — Critical conditions
3 — Error conditions
4 — Warning conditions
5 — Normal but significant condition
6 — Informational
7 — Debug-level messages
8 — All
Read: man dmesg