The Systemd Service Diagnostics skill provides comprehensive troubleshooting for Linux systemd service management. It queries service status using systemctl show with machine-readable property output, then correlates failures with structured log data from journalctl –output=json.

The skill handles common failure patterns: services stuck in activating state (analyzing ExecStartPre dependencies), repeated restart loops (checking RestartSec and StartLimitBurst configurations), socket activation failures (verifying ListenStream bindings), and permission denied errors (auditing User/Group, CapabilityBoundingSet, and SELinux/AppArmor contexts).

Unit file analysis uses systemd-analyze verify to detect configuration errors, systemd-analyze security to score service sandboxing (ProtectSystem, PrivateTmp, NoNewPrivileges), and systemd-analyze dot to generate dependency graphs that reveal ordering issues and circular dependencies.

The skill can compare unit file configurations across environments using systemd-delta to identify local overrides, and generates drop-in override files (systemctl edit) for safe configuration modifications without modifying vendor unit files.

Additional capabilities include resource usage analysis via systemd-cgtop correlation, timer unit scheduling validation (OnCalendar expression parsing), and automated generation of hardened unit files following CIS benchmark recommendations for service isolation.

Works with systemd 245+ on all major Linux distributions.