Print or control the kernel ring buffer messages.
low risk
dmesg displays kernel messages from the ring buffer — hardware detection, driver errors, disk issues, OOM killer events, and network events. The -T flag adds human-readable timestamps. Essential for diagnosing hardware failures, OOM events, and kernel panics.
| Flag | Meaning |
|---|---|
-T --ctime | Human-readable timestamps |
-l --level | Filter by level (err, warn, info, etc.) |
-f --facility | Filter by facility (kern, daemon, etc.) |
-w --follow | Follow kernel messages in real time |
--clear | Clear the ring buffer (requires root) |
dmesg -T | grep -i errorShow kernel errors with timestamps · explain & risk-check →dmesg -T | grep -i 'oom\|killed'Find OOM killer events · explain & risk-check →dmesg -T | grep -i 'sda\|nvme'Check disk/storage kernel messages · explain & risk-check →dmesg -wFollow kernel log in real time · explain & risk-check →dmesg -T | tail -50Recent kernel messages · explain & risk-check →After any unexplained process death, run `dmesg -T | grep -i killed` to check if the OOM killer was responsible — a common cause misdiagnosed as application bugs.
Reference text is hand-written and may be incomplete — check man dmesg for your version. Test destructive commands on a non-production system first.