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To: Ido Admon <rhingael@mscc.huji.ac.il>
References: <20070417145352.M39800@mscc.huji.ac.il>
	<20070417161636.GA29490@slackbox.xs4all.nl>
From: Lowell Gilbert <freebsd-questions-local@be-well.ilk.org>
Date: Tue, 17 Apr 2007 12:35:41 -0400
In-Reply-To: <20070417161636.GA29490@slackbox.xs4all.nl> (Roland Smith's
	message of "Tue\, 17 Apr 2007 18\:16\:36 +0200")
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Cc: freebsd-questions@freebsd.org
Subject: Re: Execute command upon interface initialization?
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Roland Smith <rsmith@xs4all.nl> writes:

> On Tue, Apr 17, 2007 at 06:02:25PM +0300, Ido Admon wrote:
>> Hello list,
>> I couldn't find any way to execute an arbitrary command upon network
>> interface initialization. My situations is that I have and ethernet card
>> that takes DHCP from a cables provider (not a fixed IP address) and I
>> need to update a DynDNS hostname everytime it does (everytime the IP
>> changes).
>> I couldn't find a way to execute shell commands using the rc system or
>> dhclient, what did I miss?
>
> dhclient-script(8)? Maybe devd(8) will work as well.

devd won't work as well, because the timing is a bit off (even if you
only get new addresses at boot time, which isn't guaranteed.  
 
dhclient-script already has a capability ("hooks") for running scripts
at the appropriate times.  If you check the mailing list archive, I
know I have previously posted the script I used to use for exactly the
same purpose.