Fredrik Tolf wrote:
Olivier Nicole <[EMAIL PROTECTED]> writes:

    Something like:

    minute */5 * * * root path/to/scriptname

    will do the trick.

    Substitute the * in */5 for your desired start time (* being 0).


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 <[EMAIL PROTECTED]>
Subject: test crontab 5 hours
X-Virus-Scanned: on CSIM by amavisd-milter (

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?

unset nogo
if [ -r /tmp/lastrun ]; then
    now=`date +%H`
    if [ $((($now + 24 - `cat /tmp/lastrun`) % 24)) -lt 5 ]; then

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:


while [ 1 ]; do
   exec command;
   sleep 1900 # 5 hours => 5*3600;

   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 ;)..).

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