Systemd Services, Units and Journalctl Quiz: 100 Linux System Questions

Systemd Services, Units, Timers and Journalctl Comprehensive Exam

Master the modern Linux init system and service manager with this 100-question systemd practice test. Designed for systems engineers, DevOps professionals, and Linux administrators, this assessment covers unit file authoring, dependency management, daemon lifecycles, timer-based automation, and central log inspection with journalctl.

Systemd Architecture & Topic Domains

The questions evaluate in-depth knowledge of systemd's operational features:

• Systemctl Management Commands: Managing unit states (start, stop, restart, reload, try-restart), boot configuration (enable, disable, is-enabled), checking statuses (status, is-active, is-failed), and completely preventing service activation with systemctl mask.
• Unit File Authoring & Structure: Configuring the [Unit] section (Description, Documentation, After, Before, Requires, Wants, Conflicts), [Service] execution parameters (Type=simple/forking/oneshot/notify, ExecStart, ExecReload, Restart=always/on-failure, User, Group, WorkingDirectory, EnvironmentFile), and [Install] section (WantedBy=multi-user.target).
• Process Supervision & Sandboxing Directives: RestartSec delays, StartLimitIntervalSec, ProtectSystem, ProtectHome, PrivateTmp, CapabilityBoundingSet, and enforcing resource limits using cgroups v2 integration (MemoryMax, CPUQuota).
• Targets & Boot Milestones: Understanding systemd targets as runlevel replacements (graphical.target, multi-user.target, rescue.target, emergency.target), changing active targets (systemctl isolate), and analyzing boot critical paths using systemd-analyze blame and systemd-analyze plot.
• Systemd Timers & Scheduled Automation: Creating .timer units to replace legacy cron jobs, OnCalendar monotonic vs realtime event specifications, Persistent=true behavior following system downtime, and listing active timers with systemctl list-timers.
• Log Management with Journalctl: Querying system logs using journalctl, filtering by unit (-u service), priority (-p err), boot instance (-b), time windows (--since, --until), streaming live logs (-f), kernel logs (-k), and managing journal disk size with --vacuum-size and --vacuum-time.

Realistic Service Troubleshooting Scenarios

Questions challenge you to diagnose why a custom Node.js, Python, or Go daemon fails on startup, resolve circular service dependency deadlocks, debug forking service PID tracking failures, and optimize slow server boots.