Most popular Linux/Linux operating systems have transitioned from sysvinit to systemd as the manager of system startup scripts. Citadel transitioned to systemd in late 2019.
All systemd service configuration files are located under either /lib/systemd/system or /etc/systemd/system . You'll find the following systemd scripts installed by Citadel:
The RPMs ship the following service/configuration files:
If for some reason you need to host multiple instances of Citadel Server on the same host, you could make a copy of citadel.service and call it, for example, citadel-2.service, and within the ExecStart directive specify -h/some/other/directory to run another server with its own database. Obviously you would have to run each Citadel Server on a separate IP address to avoid port conflicts. This method of running multiple instances of Citadel is known to work, but it is not officially supported -- and at the end of the day you would probably be better served by running each Citadel instance in a Docker container.