-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Dennis Peterson
Sent: Friday, April 13, 2007 9:27 AM
To: ClamAV users ML
Subject: Re: [Clamav-users] how to set cron to run freshclam
Roger M wrote:
> On Fri, 2007-04-13 at 13:26 +0200, Pascal Duchatelle wrote:
>> Hello,
>> I am not that much experienced with linux.
>> I would like to have freshclam doing updates by itself. Until now I
>> did the update manually.
>> The clamav-update file in my /etc/cron.d directory is as follow:
>>
>> ## Adjust this line...
>> MAILTO=root,postmaster,webmaster,clamav
>>
>> ## It is ok to execute it as root; freshclam drops privileges and
>> becomes ## user 'clamav' as soon as possible
> go
>
> vi /etc/cron.hourly/freshclam
>
> then add
>
> /usr/local/bin/freshclam --quiet -l /var/log/clamav/freshclam.log
>
> Then save and then:
>
> chmod 0755 /etc/cron.hourly/freshclam
>
> It will run updates every hour, if you want to update once a day then
> use cron.daily if once a week use cron.weekly.
This is pretty much a bad idea. There is a tendency to run cron jobs thus:
0 * * * * freshclam
Imagine thousands of people doing this and the load it imposes on the
servers at the top of each hour. Better is to put in a time randomizer so
that your freshclam is not fired off in lockstep with thousands of others.
This simple bash code segment has been suggested (kudos to author):
if [ -z "$1" ]; then
/usr/bin/bash -c 'sleep $[ RANDOM % 1800 ]'
fi
This creates a random number between 1 and 900 that becomes the number of
seconds the code sleeps before jumping into the fray. In this case the delay
can be up to 30 minutes (1800 seconds).
To prevent concurrent sessions from running you should keep the delay time
value less than the cron period + run time of freshclam.
The $1 allows you the option to over-ride the delay as in:
freshclam.sh now
So you might ask 'what is the benefit', and it is this: running a mirror is
a huge bandwidth hog, and helping the sysadmins balance their loads with
simple code like this shows we care about their concerns and that we respect
appreciate their contribution and show it in our usage patterns. And it may
prevent their being discouraged to the point of shutting down their mirror.
dp
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_______________________________________________
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