在crontab中使用flock（）

Question

I am using a crontab that executes a PHP file. I want to implement the flock() command to help prevent duplicate crontabs from running at one time. If I have:

* * * * * php /var/www/html/welcome.php

How can i add this flock() command? Thanks!

Answer 1

Try this:

$fh = fopen('mutex.txt','r');  // Any convenient file (MUTual EXclusion)
flock($fh, LOCK_EX);       // get exclusive lock. Will block until lock is acquired

// Do your exclusive stuff...

flock($fh, LOCK_UN);      // release lock
fclose($fh);              // close Mutex file.