How To Use journalctl to View and Manipulate systemd Logs on Linux

journalctl is a powerful command-line utility for viewing and managing systemd logs on Linux systems. It provides centralized access to kernel messages, service logs, and system events through a unified interface. The tool offers extensive filtering options by time, service units, priority levels, and custom fields, along with real-time monitoring capabilities. Key features include persistent log storage configuration, disk usage management through vacuum commands, and multiple output formats including JSON for integration with other tools. The guide covers essential commands for troubleshooting failed services, monitoring SSH access, and resolving common issues like missing logs or permission errors.