Which command loads the service configuration file for running units without stopping them?

The command that loads the service configuration file for running units without stopping them is "systemctl reload." This command is designed to send a signal to the specified service, allowing it to re-read its configuration files and apply any changes while continuing to run. This is particularly useful for applications that can adapt to configuration changes seamlessly without needing to restart, thus maintaining their operational state and minimizing downtime.

When using "systemctl reload," if the service supports it, the changes in the configuration can be applied dynamically. This command is especially beneficial in environments where uptime is critical, as it allows administrators to make necessary adjustments without interrupting service availability.

It's important to note that some services may not support reloading configuration without a full restart, but when they do, using this command facilitates that process efficiently. Other commands mentioned do not perform the same function or do not exist in the context of managing system services with systemctl.