$dataFile = "visitors.txt";

$sessionTime = 30; //this is the time in **minutes** to consider someone online before removing them from our file

//Please do not edit bellow this line

error_reporting(E_ERROR | E_PARSE);

if(!file_exists($dataFile)) {
$fp = fopen($dataFile, "w+");
fclose($fp);
}

$ip = $_SERVER['REMOTE_ADDR'];
$users = array();
$onusers = array();

//getting
$fp = fopen($dataFile, "r");
flock($fp, LOCK_SH);
while(!feof($fp)) {
$users[] = rtrim(fgets($fp, 32));
}
flock($fp, LOCK_UN);
fclose($fp);


//cleaning
$x = 0;
$alreadyIn = FALSE;
foreach($users as $key => $data) {
list( , $lastvisit) = explode("|", $data);
if(time() - $lastvisit >= $sessionTime * 60) {
$users[$x] = "";
} else {
if(strpos($data, $ip) !== FALSE) {
$alreadyIn = TRUE;
$users[$x] = "$ip|" . time(); //updating
}
}
$x++;
}

if($alreadyIn == FALSE) {
$users[] = "$ip|" . time();
}

//writing
$fp = fopen($dataFile, "w+");
flock($fp, LOCK_EX);
$i = 0;
foreach($users as $single) {
if($single != "") {
fwrite($fp, $single . "\r\n");
$i++;
}
}
flock($fp, LOCK_UN);
fclose($fp);

if($uo_keepquiet != TRUE) {
echo '

' . $i . ' visitors online

';
}

?>