DHCP client configuration script
is used by
to run any system and user defined hook scripts. System hook scripts are found
user defined hooks are
. The default install
supplies hook scripts for configuring
and the hostname. Your
distribution may have included other hook scripts to say configure ntp or
ypbind. A test hook is also supplied that simply echos the dhcp variables to
the console from DISCOVER message.
The hooks scripts are loaded into the current shell rather than executed in
their own process. This allows each hook script, such as
environment variables or provide alternative functions to hooks further down
the chain. As such, using the shell builtins
or similar will cause
to exit at that point.
is set to the interface that
is run on and
is to the reason why
was invoked. DHCP
information to be configured is held in variables starting with the word new_
and old DHCP information to be removed is held in variables starting with the
can display the full list
of variables it knows how about by using the
Here's a list of reasons why
could be invoked:
- dhcpcd is starting up and any pre-initialisation should be done.
- dhcpcd has detected the carrier is up. This is generally just a
notification and no action need be taken.
- dhcpcd lost the carrier. The cable may have been unplugged or association
to the wireless point lost.
- dhcpcd informed a DHCP server about it's address and obtained other
- dhcpcd obtained a new lease from a DHCP server.
- dhcpcd renewed it's lease.
- dhcpcd has rebound to a new DHCP server.
- dhcpcd successfully requested a lease from a DHCP server.
- dhcpcd assigned a delegated prefix to the interface.
- dhcpcd obtained an IPV4LL address, or one was removed.
- dhcpcd has been configured with a static configuration which has not been
obtained from a DHCP server.
- dhcpcd is monitoring the interface for a 3rd party to give it an IP
- dhcpcd failed to contact any DHCP servers but was able to use an old
- dhcpcd's lease or state expired and it failed to obtain a new one.
- dhcpcd received a NAK from the DHCP server. This should be treated as
- dhcpcd has been instructed to reconfigure an interface.
- dhcpcd has received an IPv6 Router Advertisement, or one has expired.
- dhcpcd stopped running on the interface.
- dhcpcd has stopped entirely.
- The interface has been removed.
- dhcpcd failed to operate on the interface. This normally happens when
dhcpcd does not support the raw interface, which means it cannot work as a
DHCP or ZeroConf client. Static configuration and DHCP INFORM is still
- dhcpcd has been asked to dump the last lease for the interface.
- dhcpcd received an OFFER from a DHCP server but will not configure the
interface. This is primarily used to test the variables are filled
correctly for the script to process them.
will clear the environment variables
. The following variables will
then be set, along with any protocol supplied ones.
- the name of the interface.
- the protocol that triggered the event.
- as described above.
- the pid of
- the link status of
preference, lower is better.
$interface is wireless,
- the name of the SSID the
- A list of interfaces, in order of preference.
interface is up, otherwise
interface is down, otherwise
- Address family waiting for, as defined in
- the name of the profile selected from
- space separated list of delegated prefixes.
runs, it loads
and any scripts
found in /usr/lib/dhcpcd/dhcpcd-hooks
lexical order and then finally
Please report them to
will validate the content of each
option against its encoding. For string, ascii, raw or binhex encoding it's up
to the user to validate it for the intended purpose.
When used in a shell script, each variable must be quoted correctly.