Systemd service unit files are configuration files used by the systemd system and service manager in Linux systems. systemd acts as an init system and service manager, responsible for bootstrapping the user space and managing system processes after booting. Each service unit file represents a service and contains instructions and configurations for starting, stopping, and managing the service.
These unit files typically have a .service extension and are located in directories such as /etc/systemd/system/, /run/systemd/system/, or /lib/systemd/system/, representing system-specific, runtime, and default service unit files, respectively.
A service unit file includes several sections, most notably:
- The
[Unit]section, which describes the service with documentation and its dependencies. - The
[Service]section, which specifies the commands to start and stop the service and the behavior of the service. - The
[Install]section, which defines how the unit is installed (i.e., how the service should be automatically started at boot time).
By editing these unit files, system administrators can control the services on the system with precision.