The Kernel Ring Buffer

The kernel ring buffer is a fixed-size data structure that records kernel boot messages as well as any live kernel messages. The function of this buffer is that of logging all the kernel messages produced on boot when syslog is not yet available.

The dmesg command prints the kernel ring buffer (which used to be also stored in /var/log/dmesg).

sudo dmesg | less

dmesg options:

• -T: Shows better timestamps.
• -H: Human-readable form.
• -k: Only kernel messages.
• l: Filter by notification levels (warn, err, etc.)