单进程执行

　　

echo(date("Y-m-d H:i:s") . ">>>
");

$pid = file_get_contents("./chg_report_asc.txt");
if ($pid != "") {
        $pid = intval($pid);
        if (posix_kill($pid, 0) == true) {
                //file_put_contents("./chg.txt", "");
                echo("other process run, return
");
                return;
        }
}
$pid = posix_getpid();
file_put_contents("./chg_report_asc.txt", $pid);