dmesg.md

dmesg TODO

Print the system log:

dmesg

http://www.web-manual.net/linux-3/the-kernel-ring-buffer-and-dmesg/

TODO what kernel function puts messages there?

The messages that appear on the screen at startup are shown there as well. But there are messages which only dmsg shows. TODO what is the difference?

Also clear the ring buffer:

sudo dmesg -c

Good option, so that next time you run:

sudo dmesg -c

you know that all messages are new.

/var/log/dmesg

http://unix.stackexchange.com/questions/191560/difference-between-output-of-dmesg-and-content-of-var-log-dmesg

When the kernel finishes booting, it dumps the ring buffer to this file.

The messages are found in /var/log/dmesg and rotated log files dmesg.N.gz.

After boot, further messages are written to the ring buffer, and dmesg will see them, but they are not written to /var/log/dmesg.

At that point, there seem to be

/var/log/dmesg.0

dmesg from last boot.

/proc/kmsg

kmsg

Looks like a live ring-buffer.

Try:

sudo cat /proc/kmsg

and then connect and disconnect something like a USB cable.

/var/log/boot.log

TODO what kernel function puts messages there? Looks like service startup / teardown, so possibly upstart?

/var/log/kern.log

Large log of multiple previous ring buffers.

Set under /etc/rsyslog.d/50-default.conf.

/var/log/messages

Not present in Ubuntu 16.04.

http://unix.stackexchange.com/questions/35851/whats-the-difference-of-dmesg-output-and-var-log-messages

klogd

TODO. Daemon that polls the kernel log: http://unix.stackexchange.com/a/35853/32558 ?

syslogd

/var/log/sysloc

TODO. Daemon that polls the kernel log: http://unix.stackexchange.com/a/35853/32558 ?

http://askubuntu.com/questions/26237/difference-between-var-log-messages-var-log-syslog-and-var-log-kern-log

rsyslog

http://www.rsyslog.com/