Documentation for dhclient.

[Glenn Satchell]

On 05/11/11 19:38, Peter Rathlev wrote:
> On Tue, 2011-05-10 at 17:41 -0700, Stephan Tiriac wrote:
>> Maybe you could tell me what's the difference between the  -r and -x
>
> What version of dhcp do you use? Are you sure it's not some old release?
>
> The stock dhclient in Fedora 13 (dhclient-4.1.2-4.ESV.R2.fc13.x86_64)
> has a very well documented dhclient. The current plain vanilla version
> (dhcp-4.2.1-P1) has the same information in the "client/dhclient.8" man
> page.
>
>    -r   Release the current lease and stop the running DHCP client as
>         previously recorded in the PID file.  When shutdown  via this
>         method dhclient-script(8) will be executed with the specific
>         reason for calling the script set.  The client normally doesn’t
>         release the current lease as this is not required by the DHCP
>         protocol but some cable ISPs require their clients to notify
>         the server if they wish to release an assigned IP address.
>
>    -x   Stop  the  running  DHCP  client  without  releasing the
>         current lease.  Kills existing dhclient process as previously
>         recorded in the PID file.  When shutdown via this method
>         dhclient-script(8) will be executed with the specific  reason
>         for calling the script set.
>
> I wouldn't call that "poorly documented".
>

This is from the dhclient 3.0.5 man page:


      The client normally doesn't release the current lease as  it
      is  not  required  by  the  DHCP  protocol.  Some cable ISPs
      require their clients to notify the server if they  wish  to
      release  an  assigned  IP  address.   The -r flag explicitly
      releases the current lease, and  once  the  lease  has  been
      released, the client exits.

The -x option doesn't seem to exist in this version.

This is from dhclient 3.1.2, it includes that 3.0.5 paragraph above and 
adds this as well

      If the client is killed by a signal (for example at shutdown
      or reboot) it won't execute the dhclient-script (8) at exit.
      However if you shut the client down gracefully with -r or -x
      it  will  execute  dhclient-script  (8) at shutdown with the
      specific reason for calling the script set.

-- 
regards,
-glenn