You can take into account the accidental kill by putting some monitor script in the crontab itself - but you would have an explosion of scripts :)

My previous solution was clean in the sense that it voids active waits. If you don't bother having slightly active waits, you could keep a queue file in each directory, with write access protected via a lock, in which you append your 'name' (e.g. pid number), then keep controlling until it's your turn. When you're done, you simply remove yourself from the top of the file (using the same locking to prevent multiple writings). In this way, the access to the queue file should be rather quick, then a check every second should suffice without slowing your machine to a crawl.

Note that if you use PIDs, you can also check if the current first-in-the-list is alive, just to prevent infinite locking by a badly dead script.

Flavio

Don't fool yourself.

In reply to Re^3: Locking/unlocking program execution using a queue by polettix
in thread Locking/unlocking program execution using a queue by RazorbladeBidet

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