Controlling the init system for my package

[Tong Sun <suntong001@users.sourceforge.net>]

Hi,

How to enable the daemon from my package to be started when machine boot?

I used to use SysV & update-rc.d, however,

As per
 https://wiki.debian.org/systemd

| systemd is a system and service manager for Linux. It is the default
init system for Debian since Debian Jessie. Systemd is compatible with
SysV and LSB init scripts. It can work as a drop-in replacement for
sysvinit.

And as per

https://www.digitalocean.com/community/tutorials/how-to-use-systemctl-to-manage-systemd-services-and-units

| systemctl command, ... is the central management tool for
controlling the init system.

and also as I've got warnings like

postrm-contains-additional-updaterc.d-calls

So I changed my post install/rm from using update-rc.d to use systemctl instead.

Now I've just learned that systemctl should not be inside the post
install/rm scripts.

Thus,

What's the correct way to install/enable/remove the daemon from my
package inside the post install/rm scripts?

Thanks!