What Is a Systemd Unit?
A systemd unit is a declarative file that tells systemd how to manage a particular resource, most commonly a service but also sockets, mounts, devices, and timers. It specifies what to start, ordering and dependency relationships, restart policy, and resource limits. Systemd reads these units to bring the system to its desired state.
Why it matters
Background agents on a runner, including the CI agent itself, are commonly managed as systemd service units. Knowing the unit format is how you control startup order, restarts, and resource caps for those processes.
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