On 2021-03-19 11:24, D. Hugh Redelmeier via talk wrote:
[One reason for this message is to test if the mailing list is working. I haven't seen a new message in a 10 days.]
dmseg command =============
The dmesg command shows you the kernel log. It takes the log from the kernel itself. It is stored in a circular RAM buffer, so you can still read it if the normal logging system isn't working. This buffer is a fixed size so older messages can get pushed out by newer ones if there is enough logging going on.
You can get more info on Fedora by journalctl -b but it isn't limited to kernel messages. It does colour-code messages based on severity, so that's a nice plus. Since this log typically goes to disk, it tends to be complete. Oh: the -b flag means: start from the most recent boot -- logs can go back months and years.
As an old timer, my first instinct is to use dmesg.
looking at kernel messages ==========================
dmesg | less -i
dmesg pours out a lot of lines. less is a good way of navigating this log. The -i makes searches within less case-insensitive.
A good read. Thanks for sharing! Small note: On Debian (and other distros?) if a non-root user runs dmesg to read the contents of the kernel message buffer they will see ... dmesg: read kernel buffer failed: Operation not permitted Turns out it is a security feature - https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=842226#15 To allow users to read the kernel log without being prompted for a password, modify /etc/sysctl.conf by adding ... kernel.dmesg_restrict = 0 ... and reload the configuration ... $ sudo sysctl -p