My lockfile system
<?php
function isLocked(){
if(file_exists(LOCK_FILE)) {
$lockingPID = trim(file_get_contents(LOCK_FILE));
$test=trim(`ps -p $lockingPID -o pid=`);
if(!empty($test)) return true;
echo "Removing stale lock file.\n";
unlink(LOCK_FILE);
}
file_put_contents(LOCK_FILE, getmypid()."\n");
return false;
}
?>