dhcpcd/hooks/dhcpcd-run-hooks.8.in

.\" Copyright (c) 2006-2023 Roy Marples
.\" All rights reserved
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.Dd August 31, 2022
.Dt DHCPCD-RUN-HOOKS 8
.Os
.Sh NAME
.Nm dhcpcd-run-hooks
.Nd DHCP client configuration script
.Sh DESCRIPTION
.Nm
is used by
.Xr dhcpcd 8
to run any system and user defined hook scripts.
System hook scripts are found in
.Pa @HOOKDIR@
and the user defined hooks are
.Pa @SYSCONFDIR@/dhcpcd.enter-hook .
and
.Pa @SYSCONFDIR@/dhcpcd.exit-hook .
The default install supplies hook scripts for configuring
.Pa /etc/resolv.conf
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.
.Pp
The hooks scripts are loaded into the current shell rather than executed
in their own process.
This allows each hook script, such as
.Pa @SYSCONFDIR@/dhcpcd.enter-hook
to customise environment variables or provide alternative functions to hooks
further down the chain.
As such, using the shell builtins
.Ic exit ,
.Ic exec
or similar will cause
.Nm
to exit at that point.
.Pp
Each time
.Nm
is invoked,
.Ev $interface
is set to the interface that
.Nm dhcpcd
is run on and
.Ev $reason
is set to the reason why
.Nm
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 word old_.
.Nm dhcpcd
can display the full list of variables it knows about by using the
.Fl V , -variables
argument.
.Pp
Here's a list of reasons why
.Nm
could be invoked:
.Bl -tag -width EXPIREXXXEXPIRE6
.It Dv PREINIT
dhcpcd is starting up and any pre-initialisation required should be performed now.
.It Dv CARRIER
dhcpcd has detected the carrier is up.
This is generally just a notification and no action need be taken.
.It Dv NOCARRIER
dhcpcd lost the carrier.
The cable may have been unplugged or association to the wireless point lost.
.It Dv NOCARRIER_ROAMING
dhcpcd lost the carrier but the interface configuration is persisted.
The OS has to support wireless roaming or IP Persistence for this to happen.
.It Dv INFORM | Dv INFORM6
dhcpcd informed a DHCP server about its address and obtained other
configuration details.
.It Dv BOUND | Dv BOUND6
dhcpcd obtained a new lease from a DHCP server.
.It Dv RENEW | Dv RENEW6
dhcpcd renewed its lease.
.It Dv REBIND | Dv REBIND6
dhcpcd has rebound to a new DHCP server.
.It Dv REBOOT | Dv REBOOT6
dhcpcd successfully requested a lease from a DHCP server.
.It Dv DELEGATED6
dhcpcd assigned a delegated prefix to the interface.
.It Dv IPV4LL
dhcpcd obtained an IPV4LL address, or one was removed.
.It Dv STATIC
dhcpcd has been configured with a static configuration which has not been
obtained from a DHCP server.
.It Dv 3RDPARTY
dhcpcd is monitoring the interface for a 3rd party to give it an IP address.
.It Dv TIMEOUT
dhcpcd failed to contact any DHCP servers but was able to use an old lease.
.It Dv EXPIRE | EXPIRE6
dhcpcd's lease or state expired and it failed to obtain a new one.
.It Dv NAK
dhcpcd received a NAK from the DHCP server.
This should be treated as EXPIRE.
.It Dv RECONFIGURE
dhcpcd has been instructed to reconfigure an interface.
.It Dv ROUTERADVERT
dhcpcd has received an IPv6 Router Advertisement, or one has expired.
.It Dv STOP | Dv STOP6
dhcpcd stopped running on the interface.
.It Dv STOPPED
dhcpcd has stopped entirely.
.It Dv DEPARTED
The interface has been removed.
.It Dv FAIL
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 allowed.
.It Dv TEST
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.
.El
.Sh ENVIRONMENT
.Nm dhcpcd
will clear the environment variables aside from
.Ev $PATH .
The following variables will then be set, along with any protocol supplied
ones.
.Bl -tag -width xnew_delegated_dhcp6_prefix
.It Ev $interface
the name of the interface.
.It Ev $protocol
the protocol that triggered the event.
.It Ev $reason
as described above.
.It Ev $pid
the pid of
.Nm dhcpcd .
.It Ev $ifcarrier
the link status of
.Ev $interface :
.Dv unknown ,
.Dv up
or
.Dv down .
.It Ev $ifmetric
.Ev $interface
preference, lower is better.
.It Ev $ifwireless
.Dv 1 if
.Ev $interface
is wireless, otherwise
.Dv 0 .
.It Ev $ifflags
.Ev $interface
flags.
.It Ev $ifmtu
.Ev $interface
MTU.
.It Ev $ifssid
the SSID the
.Ev interface
is connected to.
.It Ev $interface_order
A list of interfaces, in order of preference.
.It Ev $if_up
.Dv true
if the
.Ev interface
is up, otherwise
.Dv false .
This is more than IFF_UP and may not be equal.
.It Ev $if_down
.Dv true
if the
.Ev interface
is down, otherwise
.Dv false .
This is more than IFF_UP and may not be equal.
.It Ev $af_waiting
Address family waiting for, as defined in
.Xr dhcpcd.conf 5 .
.It Ev $profile
the name of the profile selected from
.Xr dhcpcd.conf 5 .
.It Ev $new_delegated_dhcp6_prefix
space-separated list of delegated prefixes.
.El
.Sh FILES
When
.Nm
runs, it loads
.Pa @SYSCONFDIR@/dhcpcd.enter-hook ,
any scripts found in
.Pa @HOOKDIR@
in lexical order, then finally
.Pa @SYSCONFDIR@/dhcpcd.exit-hook .
.Sh SEE ALSO
.Xr dhcpcd 8
.Sh AUTHORS
.An Roy Marples Aq Mt roy@marples.name
.Sh BUGS
Please report them to
.Lk https://roy.marples.name/projects/dhcpcd
.Sh SECURITY CONSIDERATIONS
.Nm dhcpcd
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.
.Pp
When used in a shell script, each variable must be quoted correctly.