How to prevent PHP script running more than once?

Question

Currently, I tried to prevent an onlytask.php script from running more than once:

$fp = fopen(\"/tmp/\".\"onlyme.lock\", \"a+\");
if (flock($fp,         


        

Answer 1

try using the presence of the file and not its flock flag :

$lockFile = "/tmp/"."onlyme.lock";
if (!file_exists($lockFile)) {

  touch($lockFile); 

  echo "task started\n";
  //
  // do something lengthy
  //

  unlink($lockFile); 

} else {
  echo "task already running\n";
}