What do you know about writing code in PHP running on Linux like scronjob ????
That's a bit of a broad/vague question. What do you want to know exactly?
It's highly unrecommended, but you can do it. Generally, if your host wont let you cron something, they wont be happy with you trying to fake a cron.
Now, there's nothing wrong with a triggered event (first time page loads for the day, for example), though you have to be careful not to multiple-run.