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Linux Intermediate

What is Journalctl?

A command-line tool for querying and viewing logs collected by systemd's journal logging system.

Journalctl provides structured log access. Common usage: journalctl -u nginx (service logs), journalctl --since "1 hour ago" (time-based), journalctl -f (follow/tail), journalctl -p err (priority filtering).

The journal stores logs in a binary format, enabling fast querying, filtering by service/priority/time, and automatic log rotation. It replaces traditional text-based syslog for many use cases.

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