First, I write a simple PHP script<?phpwhile(true)  {    echo 'hey'.PHP_EOL;    sleep(1);  }Then I run it like:php test.php &Obviously goes into background, but keeps running and prints hey repeatedly.Now run it like:php test.phpand hit Ctrl+Z while it is running. It goes into background but stops running.Why stop running? How to keep it running while it goes into background? Think of time when you run something and in the middle of it, you realize you should do something real quick.
Explanation for background tasks on bash
bash;background process
Ctrl-z sends SIGTSTP to the process, suspending it. To background it properly you need to run bg afterwards.