systemctl vs systemd vs service — What’s the Difference?

On modern Linux systems, you’ll often see references to systemd, systemctl, and service. Here’s a concise breakdown of what each does, their roles, and when to use them.

systemd

✅ What it is
A system and service manager for Linux, designed to unify service behavior across distributions. It replaces older init systems (like SysV init) and is responsible for managing the entire system lifecycle — from boot to shutdown.

✅ Key Role

• It’s the first process started by the Linux kernel (PID 1) and manages the whole system.
• Handles services (units), sockets, mount points, and more.

✅ Configuration Files

• System unit files: /etc/systemd/system/*.service (custom)
• Package unit files: /lib/systemd/system/*.service

systemctl

✅ What it is
The main command-line interface for interacting with systemd.

✅ Key Role

• Allows you to control and manage systemd units (services, sockets, timers, etc.).
• Common actions: start, stop, enable, disable, and get status of units.

✅ Example Commands

• systemctl start nginx
• systemctl status sshd
• systemctl enable apache2

service

✅ What it is
A legacy command that originated from SysV init to manage services.

✅ Key Role

• Provides a consistent way to start, stop, and check the status of services, even across different init systems.

✅ Example Commands

• service nginx start
• service ssh status

On modern systems using systemd, service often acts as a compatibility layer and internally redirects to systemctl commands.

Summary Table

Final Tips

• On modern Linux systems, prefer using systemctl for full feature access and better control.
• Use service only if you’re working with legacy scripts or older environments.