OnUnitActiveSec

OnUnitActiveSec is a systemd timer directive used primarily in Linux-based operating systems to specify the duration of activity for a unit, typically a service unit, in terms of active seconds. It defines the maximum amount of time that a unit is allowed to remain active during its operation before being automatically terminated or restarted, ensuring efficient resource management and system stability.

This directive is often employed in scenarios where a process or job needs to run for a precise period, such as for time-bound batch jobs, testing, or certain automated tasks. When set, OnUnitActiveSec counts from the point the unit becomes active, and once the specified duration elapses, systemd can take predefined actions—such as stopping the unit or triggering other dependent units.

OnUnitActiveSec is usually used alongside other timer directives such as OnActiveSec or OnBootSec to create complex scheduling policies. Its value is specified as an integer representing seconds, allowing for flexible time control within system configuration files, typically within the unit or timer files.

A key feature of OnUnitActiveSec is its ability to help enforce time limits on service operation, preventing runaway processes and ensuring that system resources are allocated efficiently. It is part of systemd's event-driven management framework and is crucial for maintaining predictable and reliable service behavior.

Overall, OnUnitActiveSec provides a simple yet effective mechanism for controlling the active duration of units in systemd-managed environments, aiding system administrators in achieving precise operational timing and resource utilization.