dhclient-script, hooks, and changing the environment

[Brian May]

martin f krafft wrote:
> Anything else? Do you know of packages that rely on this
> functionality? Do you have scripts of your own which modify the
> environment? Would you please be so kind as to explain to me what
> they do, and help me figure out whether there isn't a better way for
> them?
>   
My suggestion:

    * Look at any package in unstable that provides files in
      </etc/dhcp3/dhclient-*-hooks.d>. I suspect this won't be many to
      look at. Check that none of these packages do anything weird.
    * Don't include this (stupid) functionality in netconf.
    * Solve any issues that occur on a case by case basis, e.g. it
      sounds like Theodore Tso's issue can be solved within netconf.
    * Document this somewhere.

I suspect anything that relies on changing environment variables like 
this solves a problem that would better be solved within netconf itself. 
However this is going to have to be determined on a case by case basis.

On my installed system (ok, this is Ubuntu Hardy but I suspect Debian 
will be similar if not identical):

/etc/dhcp3/dhclient-enter-hooks.d:

total 12

-rwxr-xr-x 1 root root 1096 2008-03-21 21:56 avahi-autoipd*

-rw-r--r-- 1 root root 1018 2008-04-03 00:37 debug

-rwxr-xr-x 1 root root 1753 2008-04-03 08:30 samba*


/etc/dhcp3/dhclient-exit-hooks.d:

total 16

-rw-r--r-- 1 root root 1024 2008-04-03 00:37 debug

-rw-r--r-- 1 root root  802 2008-03-08 07:37 ntpdate

-rwxr-xr-x 1 root root 1097 2008-03-21 21:56 zzz_avahi-autoipd*

-rw-r--r-- 1 root root  333 2007-10-24 00:37 zzzz_dhcdbd


At a quick glance none of these appear to change any environment 
variables. They are read-only operations only.

Brian May