How do I create a custom systemd service?

Create a .service file in /etc/systemd/system/ with [Unit], [Service], and [Install] sections. Set ExecStart to your command, Type to appropriate value (simple, forking, oneshot). Run daemon-reload then enable.

Why does my service fail immediately after starting?

Check journalctl -u service for the error. Common causes: wrong ExecStart path, missing config file, permission denied, or the application exiting with an error code. Type=forking requires the process to actually fork.

Systemctl Service Errors — Failed to Start, Dependency, and Unit File Issues

Q: What does 'masked' mean for a service?

A masked service is linked to /dev/null, preventing it from being started by any method. Use systemctl unmask servicename to unmask it. This is stronger than disabling.

Errorsystemd

Overview

Fix systemctl service errors including failed to start, dependency failures, unit file syntax errors, and troubleshooting services that refuse to start.

Key Details

systemctl is the primary tool for managing systemd services on modern Linux distributions
Service unit files are stored in /etc/systemd/system/ (admin) and /lib/systemd/system/ (packages)
Failed services show red dot in systemctl status — the journal contains detailed failure reasons
Dependencies between services can cause cascading failures if one service fails
Masking a service prevents it from being started by any means (manual, dependency, socket)

Common Causes

Service binary not found at the path specified in the unit file
Configuration file syntax error causing the service to crash on startup
Dependency service not running or not installed
Port already in use by another process
Insufficient permissions: service trying to bind to a privileged port (<1024) as non-root

Steps

1Check service status: systemctl status servicename — shows active/failed state and recent logs
2View full journal: journalctl -u servicename -n 50 --no-pager for detailed error messages
3Verify unit file syntax: systemd-analyze verify /etc/systemd/system/myservice.service
4After editing a unit file: systemctl daemon-reload to reload the configuration
5Check for port conflicts: ss -tlnp | grep :PORT to see what is using the port
6Unmask a service: systemctl unmask servicename if it was previously masked

More in Systemd

linux-systemd-service-failedLinux systemd Service Failed to Start — Unit Entered Failed State

Error

linux-systemd-dependency-failedLinux systemd Dependency Failed — Service Cannot Start

Error

linux-systemd-journal-errorsLinux systemd Journal Errors — Failed Services, Dependencies & Timers

Warning

linux-journalctl-usage-guideJournalctl Usage Guide — Reading System Logs and Debugging Services

Informational

linux-systemd-timer-errorsSystemd Timer Errors — Replacing Cron with Systemd Timers and Troubleshooting