Managing systemd Services: A Comprehensive Guide to Starting, Stopping, and Configuring

Introduction / Why This Is Needed

Systemd has become the standard for managing services and processes in most modern Linux distributions (Ubuntu, Fedora, CentOS/RHEL 8+, Debian 10+). Understanding its fundamentals is an essential skill for a system administrator and developer working with servers.

This guide will provide you with practical skills for everyday service management: starting, stopping, configuring autostart, and diagnosing failures. You will be able to confidently work with commands such as systemctl and journalctl.

Requirements / Preparation

• A Linux distribution with the systemd initialization system (check with: pidof systemd).
• Terminal access with sudo privileges (for managing system services).
• Basic understanding of the command line.

Step 1: Basic Service State Management Commands

Systemctl is the primary tool for interacting with systemd. Here are the key commands for managing service state:

• Start a service:

  sudo systemctl start имя_службы.service
  

  Example: sudo systemctl start nginx
• Stop a service:

  sudo systemctl stop имя_службы.service
  

• Restart a service (graceful):

  sudo systemctl restart имя_службы.service
  

• Forceful restart (kill and start):

  sudo systemctl try-restart имя_службы.service
  

  💡 Tip: For web servers (nginx, apache), after changing the configuration, use reload (sudo systemctl reload nginx) to reread the config without dropping connections.

Step 2: Managing Autostart (Enable/Disable)

For a service to start automatically at system boot, it must be enabled.

• Enable autostart:

  sudo systemctl enable имя_службы.service
  

  This command creates a symbolic link to the unit file in the /etc/systemd/system/ directory.
• Disable autostart:

  sudo systemctl disable имя_службы.service
  

• Check if a service is enabled for autostart:

  systemctl is-enabled имя_службы.service
  

  Output: enabled (enabled), disabled (disabled), static (cannot be enabled directly but can be a dependency), masked (completely blocked).

Step 3: Viewing Status and All Services

• Detailed status of a specific service:

  systemctl status имя_службы.service
  

  The output shows: Active: (state), Main PID: (process identifier), and the last lines of the service's journal.
• List all loaded (active) units:

  systemctl list-units --type=service
  

• List ALL available services (including inactive ones):

  systemctl list-units --type=service --all
  

• Search for a service by name:

  systemctl list-units --type=service --all | grep -i ssh
  

Step 4: Analyzing Logs with journalctl

Systemd logs are stored in a binary journal, accessible via journalctl.

• View logs for a specific service:

  sudo journalctl -u имя_службы.service
  

• Follow logs in real-time (like tail -f):

  sudo journalctl -u имя_службы.service -f
  

• Logs from the last system boot:

  sudo journalctl -b
  

• Logs filtered by time:

  sudo journalctl --since "2026-02-15 10:00:00" --until "2026-02-15 12:00:00"
  

• Show logs with maximum verbosity for a service:

  sudo journalctl -u имя_службы.service -o verbose
  

Step 5: Additional Operations (Reload Configuration, Masking)

• Reload systemd configuration (mandatory after creating/modifying unit files):

  sudo systemctl daemon-reload
  

• Full service block (mask) — prevents any manual or automatic start:

  sudo systemctl mask имя_службы.service
  

  Creates a symbolic link to /dev/null. To unmask: sudo systemctl unmask имя_службы.service.
• Force stop and reset service state:

  sudo systemctl reset-failed имя_службы.service
  

  Useful if a service is in a failed state and won't start after fixing the error.

Verification

1. To verify operation: run systemctl status имя_службы. Ensure the Active: line contains active (running).
2. To verify autostart: reboot the system (sudo reboot) and after logging in, check the service status.
3. To verify logs: ensure journalctl -u имя_службы shows no errors (failed, error, permission denied).

Potential Issues

• Error Failed to start ... or Unit not found.
  • Cause: The unit file is missing or has an incorrect name. Ensure the service exists: systemctl list-unit-files | grep имя_службы. Check the unit file syntax: sudo systemd-analyze verify /etc/systemd/system/имя_службы.service.
• Service starts but immediately stops.
  • Cause: An error in the application itself or incorrect parameters in the [Service] section (e.g., ExecStart points to a non-existent binary). Check detailed logs: sudo journalctl -u имя_службы.service -n 50 --no-pager.
• Permission denied when trying to manage a system service.
  • Cause: You are running the command without sudo. Managing system services (from /etc/systemd/system/) requires root privileges.
• Service does not enable for autostart (enable fails).
  • Cause: The unit file has an [Install] section but lacks WantedBy= or RequiredBy= (most commonly WantedBy=multi-user.target). Add this line to the unit file and run daemon-reload and enable again.
• Restart loops (cyclic restarts).
  • Cause: The [Service] section in the unit file contains Restart=always (or on-failure), and the process exits immediately with an error. Fix the application error or temporarily comment out Restart for diagnostics.