Only allowing a script to run once at a time...

[m002.p]

Hi everyone,

I have a script that runs every 3 seconds kickstarted by CRON every minute. I want to however stop the script overlapping itself as it sometimes does, so in short, I would like to only allow it to run once per time.

So I formulated a method without using MYSQL, a simple .txt file check as follows. The only issue is sometimes it forgets to remove the file so I end up with a script not running at all. In addition it places these files in the very root of the server not in the directory the script runs. Could this be something to do with it?

PHP Code:

<?php
$fileN = "check.txt";
$filename = '/public_html/serverchecks/$fileN';

if (file_exists($filename)) {
    exit();

}else{

$ourFileHandle = fopen($fileN, 'w') or die("can't open file");
fclose($ourFileHandle);

}

// Script code HERE

unlink($fileN); 

?>

Any ideas?

Thanks in advance.

Matt