How to make a shell script accessible by ip?

Question

PHP

in case an unscrupulous customer decides to close access to hosting without paying, I want to leave some kind of shell script that in this case can be run.
how to implement this?
or offer your own version for such a case
, here’s another idea to put the text of the command itself on some url
and on the server (there is ssh) run a script that opens this url every minute and executes the command
initially this url returns empty, in which case I edit it on command text and all

Answer 1

If you don’t know how to organize such a simple thing, then for now you should not think about money, but about your reputation, and improve your work skills.
Without sarcasm, quite seriously - gain work experience, and do not leave stubs for those who suddenly underpay you a little money.

Answer 2

If there is a web server there, you can run it through a URL known only to you, which must first be programmed in the server part of the site. If not, you can make a daemon that will listen on any port, and when accessed, it will start something.