note 36859 modified in function.getmypid by danbrown

One good use for this is deciding on a concurrency-safe temporary file or directory name. You can be assured that no two processes on the same server have the same PID, so this is enough to avoid collisions. For example: <?php $tmpfile = "/tmp/foo_".getmypid(); // Use $tmpfile... // Use $tmpfile... // Use $tmpfile... unlink ($tmpfile); ?> If you are sharing /tmp over the network (which is odd....) then you can, of course, mix in the PHP server's IP address. --was-- One good use for this is deciding on a concurrency-safe temporary file or directory name. You can be assured that no two processes on the same server have the same PID, so this is enough to avoid collisions. For example: $tmpfile = "/tmp/foo_".getmypid(); // Use $tmpfile... // Use $tmpfile... // Use $tmpfile... unlink ($tmpfile); If you are sharing /tmp over the network (which is odd....) then you can, of course, mix in the PHP server's IP address. http://php.net/manual/en/function.getmypid.php