Explanation for background tasks on bash

Question

First, I write a simple PHP script

<?php
while(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.php

and 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.

Answer 1

Ctrl-z sends SIGTSTP to the process, suspending it. To background it properly you need to run bg afterwards.