Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!usc!snorkelwacker!mit-eddie!aryeh
From: aryeh@eddie.mit.edu (Aryeh M. Weiss)
Newsgroups: comp.unix.xenix
Subject: Re: cron
Message-ID: <1990Feb10.193851.16968@eddie.mit.edu>
Date: 10 Feb 90 19:38:51 GMT
References: <2735@umbc3.UMBC.EDU> <269@pallas.UUCP> <22@psmsd.UUCP> <438@egrunix.UUCP>
Reply-To: aryeh@eddie.MIT.EDU (Aryeh M. Weiss)
Organization: MIT EE/CS Computer Facilities, Cambridge, MA
Lines: 13

The problem stems from the fact that cron is a 8086 program.  The way cron
works is that it computes how long it has until the next job and executes
sleep.  Unfortunately in the 8086 world the sleep argument is a 16-bit int,
which is inadequate if you only have one cron job a day!  (24 hours = 86400 
seconds)  The fix is to run a job every hour, like date, and redirect output
to /dev/null (or wherever you like).  Like others, I found this out the hard
way:  I tried sending a SIGALRM to cron, and it woke up executed the next job
it has on the queue.  The answer hit me like a diamond bullet through my brain.
Most people have something running every hour, like uudemon.hr, so this
problem is rarely seen.


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