PHP - Destroy session if not any action in 10 minutes

i've modified the answer above, and it works fine :

// inactive in seconds
$inactive = 10;
if( !isset($_SESSION['timeout']) )
$_SESSION['timeout'] = time() + $inactive; 

$session_life = time() - $_SESSION['timeout'];

if($session_life > $inactive)
{  session_destroy(); header("Location:index.php");     }

$_SESSION['timeout']=time();

I've done it with the following code:

//10 min
if( !isset($_SESSION['logout']) ){
      $_SESSION['logout'] = strtotime('+10 minutes', time()); 
    }

    if( time() > $_SESSION['logout'])
    {
      session_destroy();
        header("Location: index.php"); 
    }else{
            $_SESSION['logout'] = strtotime('+10 minutes', time());
        }
    //echo date('Y/m/d h:i:s',$_SESSION['logout']);
    //echo $_SESSION['logout'];

session_start();

// 10 mins in seconds
$inactive = 600; 

$session_life = time() - $_SESSION['timeout'];

if($session_life > $inactive) {
   session_destroy();
   header("Location: logoutpage.php");
}

$_SESSION['timeout']=time();

The code above was taken from this particular page.

Try setting the session timeout to 10 minutes.

ini_set('session.gc_maxlifetime',10);