I just needed to see if a remote web server was alive, so it didn't really matter to me whether I used ping or a curl command like this.

Here's a modified version of the original source code:

<?php

$url = 'www.google.com';
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_TIMEOUT, 5);
curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 5);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$data = curl_exec($ch);
$httpcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
if($httpcode>=200 && $httpcode<300){
  echo 'worked';
} else {
  echo "didn't work";
}

?>

As a final option, if you can run the ping command from your command line, you can also just execute it with a PHP ping script, like this:

<?php
$str = exec("ping -c 1 www.google.com");
if ($result == 0){
  echo "ping succeeded";
}else{
  echo "ping failed";
}
?>

In my case this didn't work because I wasn't given access to the ping command, but if you do have access to the ping command at the command line, this “PHP exec” example shows how this can work.

REF: https://alvinalexander.com/php/php-ping-scripts-examples-ping-command/