Manual: dhcpcd-run-hooks

DHCPCD-RUN-HOOKS(8)				   System Manager's Manual				 DHCPCD-RUN-HOOKS(8)

NAME
       dhcpcd-run-hooks — DHCP client configuration script

DESCRIPTION
       dhcpcd-run-hooks is used by dhcpcd(8) to run any system and user defined hook scripts.  System hook scripts are found
       in  /usr/libexec/dhcpcd-hooks and the user defined hooks are /etc/dhcpcd.enter-hook.  and /etc/dhcpcd.exit-hook.	 The
       default install supplies hook scripts for configuring /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.

       The hooks scripts are loaded into the current shell rather than executed in their own process.  This allows each hook
       script, such as /etc/dhcpcd.enter-hook to customise environment variables or provide alternative functions  to  hooks
       further	down the chain.	 As such, using the shell builtins exit, exec or similar will cause dhcpcd-run-hooks to exit
       at that point.

       Each time dhcpcd-run-hooks is invoked, $interface is set to the interface that dhcpcd is run on and $reason is set to
       the reason why dhcpcd-run-hooks 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_.  dhcpcd can
       display the full list of variables it knows about by using the -V, --variables argument.

       Here's a list of reasons why dhcpcd-run-hooks could be invoked:

       PREINIT		 dhcpcd is starting up and any pre-initialisation required should be performed now.

       CARRIER		 dhcpcd has detected the carrier is up.	 This is generally just a notification and no action need be
			 taken.

       NOCARRIER	 dhcpcd lost the carrier.  The cable may have been unplugged or association to	the  wireless  point
			 lost.

       NOCARRIER_ROAMING
			 dhcpcd	 lost the carrier but the interface configuration is persisted.	 The OS has to support wire‐
			 less roaming or IP Persistence for this to happen.

       INFORM | INFORM6	 dhcpcd informed a DHCP server about its address and obtained other configuration details.

       BOUND | BOUND6	 dhcpcd obtained a new lease from a DHCP server.

       RENEW | RENEW6	 dhcpcd renewed its lease.

       REBIND | REBIND6	 dhcpcd has rebound to a new DHCP server.

       REBOOT | REBOOT6	 dhcpcd successfully requested a lease from a DHCP server.

       RELEASE | RELEASE6
			 dhcpcd has released the lease.

       DELEGATED6	 dhcpcd assigned a delegated prefix to the interface.

       IPV4LL		 dhcpcd obtained an IPV4LL address, or one was removed.

       STATIC		 dhcpcd has been configured with a static configuration which has not  been  obtained  from  a	DHCP
			 server.

       3RDPARTY		 dhcpcd is monitoring the interface for a 3rd party to give it an IP address.

       TIMEOUT | TIMEOUT6
			 dhcpcd failed to contact any DHCP servers but was able to use an old lease.

       EXPIRE | EXPIRE6	 dhcpcd's lease or state expired and it failed to obtain a new one.

       NAK		 dhcpcd received a NAK from the DHCP server.  This should be treated as EXPIRE.

       RECONFIGURE	 dhcpcd has been instructed to reconfigure an interface.

       ROUTERADVERT	 dhcpcd has received an IPv6 Router Advertisement, or one has expired.

       STOP | STOP6	 dhcpcd stopped running on the interface.

       STOPPED		 dhcpcd has stopped entirely.

       DEPARTED		 The interface has been removed.

       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.

       TEST		 dhcpcd	 received an OFFER from a DHCP server but will not configure the interface.  This is primar‐
			 ily used to test the variables are filled correctly for the script to process them.

ENVIRONMENT
       dhcpcd will clear the environment variables aside from $PATH.  The following variables will then be set,	 along	with
       any protocol supplied ones.

       $interface		    the name of the interface.

       $protocol		    the protocol that triggered the event.

       $reason			    as described above.

       $pid			    the pid of dhcpcd.

       $ifcarrier		    the link status of $interface: unknown, up or down.

       $ifmetric		    $interface preference, lower is better.

       $ifwireless		    1 if $interface is wireless, otherwise 0.

       $ifflags			    $interface flags.

       $ifmtu			    $interface MTU.

       $ifssid			    the SSID the interface is connected to.

       $interface_order		    A list of interfaces, in order of preference.

       $if_configured		    true if dhcpcd has configured the interface otherwise false.

       $if_up			    true  if  the interface is up, otherwise false.  This is more than IFF_UP and may not be
				    equal.

       $if_down			    true if the interface is down, otherwise false.  This is more than IFF_UP and may not be
				    equal.

       $af_waiting		    Address family waiting for, as defined in dhcpcd.conf(5).

       $profile			    the name of the profile selected from dhcpcd.conf(5).

       $new_delegated_dhcp6_prefix  space-separated list of delegated prefixes.

FILES
       When dhcpcd-run-hooks runs, it loads /etc/dhcpcd.enter-hook, any scripts found in /usr/libexec/dhcpcd-hooks in  lexi‐
       cal order, then finally /etc/dhcpcd.exit-hook.

SEE ALSO
       dhcpcd(8)

AUTHORS
       Roy Marples 

BUGS
       Please report them to https://roy.marples.name/projects/dhcpcd

SECURITY CONSIDERATIONS
       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.

       When used in a shell script, each variable must be quoted correctly.

Debian						       October 6, 2025					 DHCPCD-RUN-HOOKS(8)