Running a program in real time?
 

How would I run a program in real time? Like... X seconds away from whenever. or months... And then be able to cancel that time, and add a new one.

Like, execute a function a day from now, but later on tonight I submit a form that says execute it 3 days from now...

Use cron jobs?

Not all cron jobs are the same is what I heard. Next to that, I don't even know how to activate them in DirectAdmin or Plesk. Got some intel on that xenon?

How would I use cron jobs from a PHP script? Is it reliable to use when managing important things?

You don't "use them from PHP'. You program the system to run some PHP scripts (e.g.: system commands) at a specified time. That's all. You can schedule a single run, a one day/week delayed task, or an hourly task. It's up to you.

Respawn: sorry, I have no clue.

You can use cron jobs to call php scripts Aaron, there's normally a button in Plesk for setting up cron jobs, just search under the domain you're managing.

Then Cron Jobs is useless to me ;-)

I dont see how it is useless to you, cron seems to be exactly what you are looking for.

From your first post a cron job is what you want. You can write a psuedo cron script in PHP but it won't be as reliable as a cron job since someone has to hit the page in order for it to execute.

If you don't have a webadministrator tool, but SSH acces to your host, then you can use the crontab command to configure running commands or php scripts at regular intervals.

this is not hard to fix,
make a batch file and you can like make a php script to excute the batch file,
or even if you want it at a time in cmd u can do as some one said here. put a time on when to start that php script,

and when to start other script or end it...

Google, is good :) ;)

Google -> batch edit + time + php so on...

;)