A cute CLI trick for emergencies
Bryn M. Reeves
bmr at redhat.com
Fri Dec 9 11:21:32 UTC 2011
On 12/09/2011 01:54 AM, jdow wrote:
> On 2011/12/08 16:56, Craig White wrote:
>> On Thu, 2011-12-08 at 09:27 -0600, Aaron Konstam wrote:
>>>> And thus the drive is /dev/sdf, with the data partition /dev/sdf1.
>>>> You may need to scroll back a bit if a lot of stuff is going on in
>>> Great, but could the displaying of the information be made more obscure?
>> dmesg | grep usb
> After the kernel ring buffer has wrapped?
> Try this:
> grep usb /var/log/dmesg
> Then you have to decode it. And, of course, the drive on which "grep" lives
> AND the drive on which /var/log/dmesg lives, if different, will be spun up.
The /var/log/dmesg file is a snapshot taken during booting (when
rc.sysinit runs) on systems using traditional SysV init (inc. upstart)
so if a device was not present during boot (or had its drivers loaded
after the snapshot was taken) it will not appear here.
It's not updated later and does not seem to be created on systems using
Either look in /var/log/messages or specify log_buf_len=n[KMG] on the
kernel command line to set a lager ring buffer (modern systems with
plenty of RAM can comfortably increase this to 10s of MB rather than the
More information about the users