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From:	"siegfried" <siegfried AT heintze DOT com>
To:	<cygwin AT cygwin DOT com>
Subject:	How to prevent duplicate cron jobs?
Date:	Fri, 21 Apr 2006 16:41:33 -0600
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I apologize if this is sent twice. I sent it once a couple of hours ago and
did not see it appear so I am sending it again.

I have a cron job running perl and it is taking a very long time -- 
sometimes over 24 hours.

How can I have cron schedule my job daily, or even hourly, and have 
the perl code  exit if a previouse instance of the job is still 
running?

Some have suggested creating a file in /tmp and checking it before 
proceding. But what if a cron job exits prematurely, perhaps because 
of a division by zero, and does not delete the /tmp file?

Others have suggested checking /proc (which seems to exist in cygwin :)) for
my pid and send a semaphore or a SIGUSR1 to determine if it's not hung.
 
Will this work in cygwin? 

Thanks,

Siegfried


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