Re: Monitoring attributes of the device

[Stephen Hemminger <shemminger@linux-foundation.org>]

On Fri, 22 Jan 2010 09:30:18 +0530
Shashank KotaSathish <Shashank_KotaSathish@mindtree.com> wrote:

> Modifying kernel. Hmmm An intriguing idea. Perhaps some other time. For the current requirement I believe netlink will do. Thanks for the clarification. I should have understood the same when udevadm monitor --kernel did not give any output when I unplugged the network cable.
> 
> Regards,
> Shashank K S
> -----Original Message-----
> From: Greg KH [mailto:greg@kroah.com]
> Sent: Thursday, January 21, 2010 11:57 AM
> To: Shashank KotaSathish
> Cc: linux-hotplug@vger.kernel.org
> Subject: Re: Monitoring attributes of the device
> 
> On Thu, Jan 21, 2010 at 10:57:26AM +0530, Shashank KotaSathish wrote:
> > Hi,
> >
> >       I wanted to know is it possible to write a rule for the udev which will run a program when the attribute of the device changes. For example if the ethernet plug is removed, the attribute "carriers" of net class will change from 1 to 0. To track this change i wrote the following rule in the /etc/udev/rules.d/70-persistent-net.rules file
> >
> > SUBSYSTEM="net", DRIVERS="?*", ATTR{carrier}="0", ATTR{address}="00:0c:29:27:a2:95", ATTR{dev_id}="0x0", ATTR{type}="1", KERNEL="eth*", RUN+="/bin/up.sh"
> >
> >  up.sh will echo some thing in to the text file  in my home directory.
> > But the up.sh is not getting executed.  Thanks in advance.
> 
> No sysfs event is getting emitted by the kernel when this attribute
> changes.  You need to modify the kernel to create such an event, and
> then your script can run.
> 
> Or you can just use ethtool and detect the carrier change that way, like
> the rest of the world does :)

Or monitor with netlink like proper tools do (see ip monitor, netlink, netplugd, quagga, ...)



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