How to check whether specified PID is currently running without invoking ps from PHP?

Question

We would like to check if a specified process is currently running via PHP.

We would like to simply supply a PID and see if it is currently executing or not.

Answer 1

//For Linux
$pid='475678';
exec('ps -C php -o pid', $a);
if(in_array($pid, $a)){
    // do something...
}