modification in dhclient-script

David W. Hankins David_Hankins at
Fri Mar 2 17:01:38 UTC 2007

On Fri, Mar 02, 2007 at 08:22:32PM +0530, hitesh sharma wrote:
> hello ,
>    i want to modify the dhclient-script , so where i will have to do ? and
> again , in this file , there are various variables , from where it get there
> values , for examples $interface ?

Some values (like $interface and $reason to name a few) are
manufactured by the dhclient program, and relate to that program's
running state.

But most values of interest are from DHCP option contents.  The
name of the shell variable is derived from the option's "option
space" and its name within that space.  The value is an ascii
representation, usually precisely like it would appear in
configuration language (but there are some odd exceptions).

These names are further prefixed with either new_ or old_,
depending on wether it's the old binding's content or the new
binding's content.

This is described in "man 8 dhclient-script", included in the
software distribution.

A simple trick I've often found useful for debugging is to add
"export > /tmp/dhcp-testing" to the top of the dhclient-script.

ISC Training!  training at
Washington DC area, April 16-20 2007.  DNS & BIND, DDNS & DHCP.
David W. Hankins	"If you don't do it right the first time,
Software Engineer		you'll just have to do it again."
Internet Systems Consortium, Inc.	-- Jack T. Hankins

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