RESOLVCONF(8)               System Manager's Manual              RESOLVCONF(8)

NAME
     resolvconf - a framework for managing multiple DNS configurations

SYNOPSIS
     resolvconf -I
     resolvconf [-m metric] [-p] [-x] -a key <file
     resolvconf -C pattern
     resolvconf -c pattern
     resolvconf [-f] -d key
     resolvconf [-x] -iLlp pattern
     resolvconf -u
     resolvconf --version

DESCRIPTION
     resolvconf manages resolv.conf(5) files from multiple sources, such as
     DHCP and VPN clients.  Traditionally, the host runs just one client and
     that updates /etc/resolv.conf.  More modern systems frequently have wired
     and wireless interfaces and there is no guarantee both are on the same
     network.  With the advent of VPN and other types of networking daemons,
     many things now contend for the contents of /etc/resolv.conf.

     resolvconf solves this by letting the daemon send their resolv.conf(5)
     file to resolvconf via stdin(4) with the argument -a key instead of the
     filesystem.  resolvconf then updates /etc/resolv.conf as it thinks best.
     If /etc/resolv.conf already exists and the top line does not match the
     expected signature, then resolvconf will refuse to update it unless the
     -u update command is given.  When a local resolver other than libc is
     installed, such as dnsmasq(8) or named(8), then resolvconf will supply
     files that the resolver should be configured to include.

     At it's heart, resolvconf is a key/value store for resolv.conf files.
     Each entry must have a unique key and should be expressed as
     interface.protocol so that it's easy to tell from where the resolv.conf
     file came from.  This also allows using pattern matching such as
     interface.* to match all protocols running on the interface.  For
     example, a modern system will likely run DHCP, RA and DHCPv6 which could
     be from separate programs or one program running many protocols.
     However, this is not a fixed requirement, resolvconf will work with any
     key name and it should be treated as an opaque value outside of
     resolvconf.

     resolvconf can mark a resolv.conf as private and optionally non-
     searchable.  This means that the name servers listed in that resolv.conf
     are only used for queries against the domain/search listed in the same
     file and if non-searchable then the domain/search listed are excluded
     from the global search list defined in /etc/resolv.conf.  This only works
     when a local resolver other than libc is installed.  See
     resolvconf.conf(5) for how to configure resolvconf to use a local name
     server and how to remove the private marking.

     resolvconf can mark a resolv.conf as exclusive.  Only the latest
     exclusive key is used for processing, otherwise all are.

     When a configuration source goes away, such as an interface going down or
     a VPN stopping, it should then call resolvconf with -d key arguments to
     clean up the resolv.conf it added previously.  For systems that support
     the concept of persisting configuration when the source is suspended,
     such as the carrier going down, then it should instead call resolvconf
     with -C key arguments to deprecate the entry -c key to activate the entry
     when it comes back again.  This only affects the order in which the
     resolv.conf entries are processed.

     Here are some options for the above commands:

     -f           Ignore non existent resolv.conf entries.  Only really useful
                  for deleting.

     -m metric    Set the metric of the resolv.conf entry  when adding it,
                  default of 0.  Lower metrics take precedence.  This affects
                  the default order of entires when listed.

     -p [pattern]
                  Marks the resolv.conf as private if the -a command is given,
                  otherwise resolv.conf entries having their key matching
                  pattern are listed.  If an extra -p is given then the
                  resolv.conf is marked as non-searchable as well.

     -x           Mark the resolv.conf as exclusive when adding, otherwise
                  only use the latest exclusive key.

     resolvconf has some more commands for general usage:

     -i [pattern]
                  List the keys stored, optionally matching pattern, we have
                  resolv.conf files for.  If the -L option is given first,
                  then the keys will be list post-processed.

     -L [pattern]
                  List the resolv.conf files we have, post-processed by the
                  resolvconf.conf(5) configuration.  If pattern is specified
                  then we list the files for the keys which match it.

     -l [pattern]
                  List the resolv.conf files we have.  If pattern is specified
                  then we list the files for the keys which match it.  that
                  match it.

     -u           Force resolvconf to update all its subscribers.  resolvconf
                  does not update the subscribers when adding a resolv.conf
                  that matches what it already has for that key.

     --version    Echo the resolvconf version to stdout.

     resolvconf also has some commands designed to be used by its subscribers
     and system startup:

     -I           Initialise the state directory /run/resolvconf.  This should
                  be called after the base state directory has either been
                  cleaned out or mounted as a memory backed filesystem during
                  the initial boot sequence before any daemon has the chance
                  to call resolvconf.

     -R           Echo the command used to restart a service.

     -r service   If the service is running then restart it.  If the service
                  does not exist or is not running then zero is returned,
                  otherwise the result of restarting the service.

     -v           Echo variables DOMAINS, SEARCH and NAMESERVERS so that the
                  subscriber can configure the resolver easily.

     -V           Same as -v except that only the information configured in
                  resolvconf.conf(5) is set.

RESOLV.CONF ORDERING
     For resolvconf to work effectively, it has to process the resolv.conf
     entries in the correct order.  resolvconf first processes keys from the
     key_order list, then entries without a metric and that match the
     dynamic_order list, then entries with a metric in order and finally the
     rest in the operating systems lexical order.  See resolvconf.conf(5) for
     details on these lists.

PROTOCOLS
     Here are some suggested protocol tags to use for each resolv.conf

     dhcp         Dynamic Host Configuration Protocol.

     ppp          Point-to-Point Protocol.

     ra           IPv6 Router Advertisement.

     dhcp6        Dynamic Host Configuration Protocol, version 6.

IMPLEMENTATION NOTES
     If a subscriber has the executable bit then it is executed otherwise it
     is assumed to be a shell script and sourced into the current environment
     in a subshell.  This is done so that subscribers can remain fast, but are
     also not limited to the shell language.

     Portable subscribers should not use anything outside of /bin and /sbin
     because /usr and others may not be available when booting.  Also, it
     would be unwise to assume any shell specific features.

ENVIRONMENT
     IF_METRIC
     If the -m option is not present then we use IF_METRIC for the metric.

     IF_PRIVATE
     Marks the resolv.conf as private.

     IF_NOSEARCH
     Marks the resolv.conf as non-searchable.

     IF_EXCLUSIVE
     Marks the resolv.conf as exclusive.

FILES
     /etc/resolv.conf.bak
     Backup file of the original resolv.conf.

     /etc/resolvconf.conf
     Configuration file for resolvconf.

     /usr/lib/resolvconf
     Directory of subscribers which are run every time resolvconf adds,
     deletes or updates.

     /usr/lib/resolvconf/libc.d
     Directory of subscribers which are run after the libc subscriber is run.

     /run/resolvconf
     State directory for resolvconf.

NOTES
     Domain labels are assumed to be in ASCII and are converted to lower case
     to avoid duplicate zones when given differing case from different
     sources.

     When running a local resolver other than libc, you will need to configure
     it to include files that resolvconf will generate.  You should consult
     resolvconf.conf(5) for instructions on how to configure your resolver.

SEE ALSO
     resolver(3), stdin(4), resolv.conf(5), resolvconf.conf(5)

HISTORY
     This implementation of resolvconf is called openresolv and is fully
     command line compatible with Debian's resolvconf, as written by Thomas
     Hood.

AUTHORS
     Roy Marples <roy@marples.name>

BUGS
     Please report them to http://roy.marples.name/projects/openresolv

Linux 6.12.107+deb13-amd64       June 26, 2025      Linux 6.12.107+deb13-amd64