dmesg
Published on 24 Mar 2004Tags #Linux
Messages that are produced by the kernel are placed in a ring buffer which has a default size of 16392 bytes. This buffer is available from userspace via /proc/kmsg. Messages are categorized into levels which are also used to decide which are printed to the console.
| Define | Level | Description |
|---|---|---|
| KERN_EMERG | - | System is unusable |
| KERN_ALERT | 1 | Action must be taken immediately |
| KERN_CRIT | 2 | Critical conditions |
| KERN_ERR | 3 | Error conditions |
| KERN_WARNING | 4 | Warning conditions |
| KERN_NOTICE | 5 | Normal but significant condition |
| KERN_INFO | 6 | Informational |
| KERN_DEBUG | 7 | Debug-level messages |
dmesg allows printing and controlling the ring buffer:
-
Show content:
dmesg -
Console verbosity level:
dmesg -n LEVEL -
Ring buffer size:
dmesg -s SIZE -
Clear ring buffer:
dmesg -c
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