Steps to reproduce:

1. Install zabbix-agent on debian 10.4
2. Run "systemctl enable zabbix-agent

Result:
This creates the file: /etc/init.d/zabbix-agent with different actions for start, stop, status, restart and a default action.

The default action defines:

echo "Usage: /etc/init.d/$NAME {start|stop|restart|force-reload|status}" >&2

/etc/init.d/$NAME does not resolve to the correct file name.

Expected:

The command should better be like:

echo "Usage: $0 {start|stop|restart|force-reload|status}" >&2

This resolves always to the correct script name.