Chapter 11: Logs and time

Read and filter the system logs, keep them across reboots and under control, keep the clock right, and use a calm method to diagnose problems.

What you will learn

• Explain journald and rsyslog and filter the journal by unit, priority, boot and time.
• Make the journal persistent, add custom rsyslog files, and rotate logs with logrotate.
• Read timedatectl and chrony output, set the time zone, and add NTP sources.
• Diagnose a failing service from its status, its journal and the wider system logs.

Sections

1. Reading the system logs
2. Exercise: Find it in the logs
3. Keeping logs: persistence and rotation
4. Exercise: Keep and rotate your logs
5. Keeping the right time
6. Exercise: Time zone and time sources
7. A method for diagnosing problems
8. Exercise: Find and fix a failing service
9. Exercise: Logs and time review
10. Linux logs and time quiz
11. Linux logs and time cheat sheet