Date: Tue, 17 Jul 2007 21:57:52 -0700 From: Garrett Cooper <youshi10@u.washington.edu> To: Fredrik Tolf <fredrik@dolda2000.com> Cc: freebsd-questions@freebsd.org Subject: Re: cron job every 5 hours Message-ID: <469D9DD0.6060609@u.washington.edu> In-Reply-To: <469D9CC2.4040902@u.washington.edu> References: <000f01c7c56d$da44d640$0200a8c0@satellite> <200707160427.l6G4Rb5q090225@banyan.cs.ait.ac.th> <469AFA30.4050504@u.washington.edu> <200707180233.l6I2XJrw097658@banyan.cs.ait.ac.th> <m3sl7miegg.fsf@pc7.dolda2000.com> <469D9CC2.4040902@u.washington.edu>
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Garrett Cooper wrote: > Fredrik Tolf wrote: >> Olivier Nicole <on@cs.ait.ac.th> writes: >> >> >>>> Something like: >>>> >>>> minute */5 * * * root path/to/scriptname >>>> >>>> will do the trick. >>>> >>>> Substitute the * in */5 for your desired start time (* being 0). >>>> >>>> -Garrett >>>> >>>> PS crond won't do 5 hours and every x number of minutes per job (5 >>>> hours + x mins from end to start), just a flat amount of time (5 >>>> hours apart from start to start). If you need that type of >>>> 'precision', at will solve that like Olivier said if you place it >>>> at the end of the command. >>>> >>> I am afraid not. >>> >>> */5 means on every hours that is a multiple of 5, not every five >>> hours. So it will run every day at hour 0, 5, 10, 15 and 20. Between >>> hour 20 one day and hour 0 the next day there is only 4 hours, not >>> the "every 5 hours" requested. >>> > That's what I meant >_>.. >>> Just to confirm that I launched a cron job yesterday: >>> >>> 23 */5 * * * /home/java/on/crontest >>> >>> It ran at 15:23, 20:23 and today at 0:23 and 5:23 and so on: >>> >>> Date: Wed, 18 Jul 2007 05:23:00 +0700 (ICT) >>> From: Olivier Nicole <on@cs.ait.ac.th> >>> To: on@banyan.cs.ait.ac.th >>> Subject: test crontab 5 hours >>> X-Virus-Scanned: on CSIM by amavisd-milter (http://www.amavis.org/) >>> >>> This is a test for crontab >>> [...] >>> Only way to run a job every 5 hours is with at(1). >>> >> >> I wouldn't go as far as saying the *only* way. You could make the cron >> job run every hour and then have an internal check in it (or using a >> wrapper script that checks it). Kind of like this, maybe? >> >> #!/bin/sh >> unset nogo >> if [ -r /tmp/lastrun ]; then >> now=`date +%H` >> if [ $((($now + 24 - `cat /tmp/lastrun`) % 24)) -lt 5 ]; then >> nogo=y >> fi >> fi >> >> if [ "$nogo" = y ]; then exit 0; fi >> >> date +%H >/tmp/lastrun >> >> # Do real work here >> > > If you're going to do it that way, just try something like this: > > #!/bin/sh > > while [ 1 ]; do > exec command; > sleep 1900 # 5 hours => 5*3600; > done > > and set it up as an rc script :). > > Shell scripts with sleep won't give you exactly the 5 hours you > desire, but should come close (within 1-5 seconds of actual time > depending on your host PC's precision, and whether or not your RTC > battery is dead ;)..). > > -Garrett That should read 19000. Doh! -Garrett
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