Because I only occasionally need to run an ftp server (vsftpd, in my case), I would prefer to just have it fully active only when the need arises.
This suggests two possibilities to me, but I don't know if both (or either) are possible..
Option 1: Do not start the daemon as the system boots up,
but instead, start it manually as the need arises... but I don't know the command(s) for this... Maybe it is just "vsftpd" and it will find its own config file(s)... but would this clash with disabling load-on-boot?
Option 2:. Start the daemon as the system boots up,
but start it in a stop/waiting mode... ie. equivalent to
sudo stop vsftpd, or
sudo initctl stop vsftpd.
I would prefer Option 1, because I rarely need an ftp server.