Memory usage (PHP)

Iam searching for a script able to calculate the per sent (%) amount of ram used by the server, for example: used 512mb of 1024mb 50%.

 

I have made this scrip:

<?php
$mem = exec("cat /proc/meminfo");
$mem = split(" ",$mem);
echo $mem[1];
?>

but the output is blank.
I want to find the exact amount of the used memory, by making the string to integer

 

Probably a permissions problem. I don't know if the webserver user is allowed to run cat /proc/meminfo.

 

You could probably do something to work around the output of free (or maybe free -l ) and/or top, just call it from within php and then process its output

 

I havn't come across that type of problem so far.I think it will be great if i am able to solve it.