Ability to read logs

Hi all guys and girls! I wanted to ask you what kind of switches for journalctl to use in order to have insight into possible failures. Using journlactl -b, I noticed quite a few errors, including the one about the data leakage by a bug in the processor. I disabled HyperThreading and quite a few of the errors disappeared, as well as the stalling during shutdown no longer happens. Is it possible to force journald to retain entries from earlier? Now only those from the current time are available. Thanks for your interest!


Check for errors

journalctl -p3 -xb

Hardware boot stopping errors

journalctl -p3 -kxb
sudo dmesg -l "err,warn"

Failed services

systemctl --failed


Xorg logfiles are located in /var/log of the form Xorg.0.log, 0 being the display number.

Current session

grep -iE "\(EE\)|\(WW\)|error|failed" "/var/log/Xorg.0.log"

Previous successful session

grep -iE "\(EE\)|\(WW\)|error|failed" "/var/log/Xorg.0.log.old"





man journalctl
man journald.conf

Journals summary size

du -sh "/var/log/journal"

If the journal is persistent (non-volatile), it’s size limit is set to a default value of 10% of the size of the underlying file system but capped at 4 GiB. For example, with /var/log/journal located on a 50 GiB partition, it would max at 4 GiB.

Supported log levels (priorities) for -p

β„– Level Description
0 emerg system is unusable
1 alert action must be taken immediately
2 crit critical conditions
3 err error conditions
4 warn warning conditions
5 notice normal but significant condition
6 info informational
7 debug debug-level messages

Previous boot

journalctl -p3 -xb -1

List available boots

journalctl --list-boots

Range of error priority

journalctl -p3..1

Live log, follow new messages

journalctl -p3 -f

New lines first

journalctl -p3 -r

Since 20 minutes ago

journalctl -p3 --since "20 min ago"

Since date (and optional time)

journalctl -p3 --since "2021-08-30 18:17:16"

Specific time period

journalctl -p3 --since="2021-08-15" --until="2021-10-16 23:59:59"

Specific binary

journalctl "/usr/lib/systemd/systemd"

Specific process

journalctl _PID=1

Specific device

journalctl /dev/sdc

So I was wrong. The log list for the boot is 6 days so far. There is something to learn. I sincerely thank you!

1 Like

Let the good times roll!


1 Like

This topic was automatically closed 2 days after the last reply. New replies are no longer allowed.