weird behaviour with forever, bash, apache and php

I'm running some node.js scripts with forever.

I started them as www-data user (i.e. via ssh logging as www-data@server and typing forever start myapp.js, etc.).

Ok, everything goes like a charm; my application works as expected, and typing forever list shows me the processes running.

Then, I wrote a (very simple) script named foreverList.sh and placed in folder /var/www/scripts/ :

#!/bin/bash echo "checking running node.js scripts:" forever list 

When I execute the script from shell as www-data user, it works. Nothing fancy here. But, this script is to be used with PHP 5.6 through Apache 2.4, with :

<?php // .... $resp_script = shell_exec("/var/www/scripts/foreverList.sh 2>&1"); echo "<pre>$resp_script</pre>"; 

And when I execute it via my web browser (so with the PHP code above), it doesn't work!! I get this forever error message (nodejs, not php):

/usr/lib/node_modules/forever/lib/forever.js:674 procs.forEach(function (proc) { ^ TypeError: Object Error: EACCES, permission denied '/root/.forever/sock' has no method 'forEach' ... ... #(stack trace follows) 

I really don't understand why it deals with /root folder, as I'm running all this stuff from /var/www/ folder and as www-data user (added a whoami in the script to check it was the case, and it does).

Do I miss something? Is it a forever bug?

Any help will be much appreciated.

UPDATE : I tried to add echo $HOME in the bash script, and it returns nothing. Does PHP itself erase the home path environment variable of www-data user?