[PLUG] seconds in cron

[Jeff Abrahamson <jeff@purple.com>]

FYI, this was Re: [PLUG] Specify seconds in cron ?
In-Reply-To: <Pine.GSO.4.33.0107180046010.10801-100000@red.seas.upenn.edu>; from sudas@seas.upenn.edu on Wed, Jul 18, 2001 at 12:46:41AM -0400

On Wed, Jul 18, 2001 at 12:46:41AM -0400, Sandhitsu R Das wrote:
> 
> I want to run something every 45 seconds ? Can I do this with cron or any
> variant ?

#!/bin/sh
do_it &    # runs at time 0
sleep 45
do_it &    # runs at time :45
sleep 45
do_it &    # runs at time 1:30
sleep 45
do_it &    # runs at time 2:15

Have cron run this every three minutes.

Note, though, that cron does not guarantee fine-grain scheduling, so
you might be off a bit. But it's close.

Why 45 seconds?


Alternatively, have cron check every few minutes that the following
shell script is still running, and if not relaunch it:

#!/bin/sh
while true; do do_it &; sleep 45; done


In all of the above you can get rid of the ampersands if the run time
for do_it is not a concern.

-- 
 Jeff

 Jeff Abrahamson  <http://www.purple.com/jeff/>



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