Use journalctl When
You are debugging services managed by systemd and want metadata-aware logs.
You need filtering by unit, boot, or time range rather than raw file reading.
Compare
journalctl vs tailing log files
When systemd journal access is better than reading raw log files directly.
Traditional log files are still common, but systemd-based systems often centralize service logs in the journal. `journalctl` lets you query and follow that data with service awareness.
Use Tailing Log Files When
The application writes directly to files and the journal is not the main source.
You are dealing with classic file-based logging workflows.
Rule of Thumb
Use journalctl for systemd services. Tail files for file-based logs.
Want the short version? Browse the compact sheet views and save the commands you use most into a Cheatbook.