Boot

Command	Example	Comment
dmesg	$ dmesg -> [ 0.000000] Linux version 4.17.4-1-ARCH (builduser@heftig-469) (gcc version 8.1.1 20180531 (GCC)) #1 SMP PREEMPT Tue Jul 3 15:45:09 UTC 2018 ...
uptime	$ uptime -> 23:44:49 up 12:08, 1 user, load average: 2.63, 1.86, 2.06

journalctl

The journalctl cannot delete logs belonging to a specific service.

• Answer (2016-06-20) by user3144605 to question journalctl - remove logs of a specific unit
• Compare answers to question How do I clear journalctl entries for a specific unit only?

Command	Example
Delete all logs except for the last time span.	journalctl --vacuum-time=2weeks
Delete all logs except for the last byte size.	journalctl --vacuum-size=100M