cron

Aryeh M. Weiss aryeh at eddie.mit.edu
Sun Feb 11 06:38:51 AEST 1990


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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