How to control (stop) a demon?

Question

linux

Found an example of a demon, launched from the console. The question is how to manage it, in particular, stop it? How to restart in case of an error? And how to make it a background so that you can write commands in the console? Thanks to.

#!/bin/bash
while true; do
    begin=`date +%s`
    php /var/www/html/rules/script.php
    end=`date +%s`
    if [ $(($end - $begin)) -lt 5 ]; then
        sleep $(($begin + 5 - $end))
    fi
done

Answer 1

man bg, fg, jobs, systemctl

Answer 2

1. The daemon must be written in such a way that it does not write to the console, but immediately write to the log file (or have a separate option for debugging to the console).
2. The daemon must be able to process signals for a graceful shutdown (the same -15), or be ready for an incorrect shutdown.
3. The daemon must be able to leave its PID, so that it would be convenient to write a wrapper to it to send signals.
ps signals can be sent via kill