I made some code to test my personal servers uptime. It logs in to my router page and sees if it returns status 200. A cron job runs it every 5 minutes. Please let me know if I can make the code more efficient.

<?php
//Date
date_default_timezone_set('America/Los_Angeles');
$date = date('m/d h:i:s a', time());

//Output
$myFile = dirname(__FILE__) . "/output.txt";
$fh = fopen($myFile, 'a+') or die("can't open file");

//Count #
$count_file = dirname(__FILE__) . "/OK.txt";
$fil = fopen($count_file, r);
$dat = fread($fil, filesize($count_file)); 
fclose($fil);
$fil = fopen($count_file, w);

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "MYURL");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_USERPWD, "USER:PASSWORD");
curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_ANY);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($ch, CURLOPT_UNRESTRICTED_AUTH, 1);
curl_exec($ch);
$retcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);


if($retcode==200){
    //fwrite($fh, "$date\tOK\n");
    $OK = $dat + 1;
    fwrite($fil, $OK);
    echo "$date\tOK\n";
    fclose($fh);
} else {
    fwrite($fh, "$date\t\tDOWN\n");
    echo "$date\tDOWN\n";
    fclose($fh);
}

//Count OK/DOWN
$read = file_get_contents($myFile);
$DOWN = preg_match_all("/DOWN/", $read, $matches) - 1;
$UP = 100*bcdiv($OK,$OK+$DOWN,4);

//Remove first line 
$read = file($myFile);
array_shift($read);
$server_up = "Server Uptime: " . $UP . "%\nOK: " . $OK . ", DOWN: " . $DOWN . "\n";
$read[0] = $server_up;
file_put_contents($myFile, $read);

?>

One thing I wanted to do was to somehow assign $OK to a variable and retrieve it the next time the page is loaded but I do not think PHP can do this so I saved it to an external file (OK.txt) and i read the value every time and increment it every time my site returns 200.

Here is a sample output.txt file

Server Uptime: 92.5%
OK: 37, DOWN: 3
09/30 06:48:28 pm   DOWN
09/30 06:48:28 pm   DOWN
09/30 06:48:28 pm   DOWN