resolvconf - manage nameserver information cat FILE | resolvconf -a INTERFACE

resolvconf -d INTERFACE

resolvconf -u

resolvconf -l PATTERN

resolvconf -i PATTERN

resolvconf -v PATTERN

resolvconf -s SERVICE COMMAND [args]

Overwrite (-a) or delete (-d) the nameserver information record for network interface INTERFACE and run the update scripts in %%PREFIX%%/etc/resolvconf/update.d/.

With -u, just run the update scripts.

With -l, list the resolv files for each interface, optionally with patterns to match interface names.

With -i, list the interfaces we have resolv files for, optionally with patterns to match interface names.

With -v, we echo variables NEWDOMAIN, NEWSEARCH and NEWNS to the console which can be used to make it easer writing scripts which configure DNS resolvers.

With -s, we work out if the service is running by finding its pidfile and if it is we restart it. This means that only resolvconf needs to know this for supported platforms and subscribers can just call this resolvconf function.

Normally resolvconf is run only by hook scripts attached to network interface configurers such as ppp (8) (for ppp interfaces), to DHCP clients such as dhcpcd (8), to network configuration scripts and openvpn , and to DNS caches such as dnsmasq (8) (for the loopback interface). However, the administrator can also run resolvconf from the command line to add or delete auxiliary nameserver information. Nameserver information provided to resolvconf is stored for use by subscribers to resolvconf's notification service. Subscribers that need to know when nameserver information has changed should install a script in %%PREFIX%%/etc/resolvconf/update.d/ (... or in %%PREFIX%%/etc/resolvconf/update-libc.d/: see below). For example, DNS caches such as dnsmasq (8) and pdnsd (8) subscribe to the notification service so that they know whither to forward queries.

The most important piece of software that subscribes to the notification service is the set of functions that make up the C Library resolver (3). When nameserver information is updated the script %%PREFIX%%/etc/resolvconf/update.d/libc writes a new resolver configuration file to %%PREFIX%%/etc/resolvconf/run/resolv.conf and then runs the scripts in %%PREFIX%%/etc/resolvconf/update-libc.d/. To make the resolver use the dynamically generated resolver configuration file the administrator should ensure that /etc/resolv.conf is a symbolic link to %%PREFIX%%/etc/resolvconf/run/resolv.conf. This link is never modified by resolvconf. If you find that /etc/resolv.conf is not being updated, check to see that the link is intact.

The C Library resolver library isn't the only resolver library available. However, any resolver library that reads /etc/resolv.conf (and most of them do, in order to be compatible with the C Library resolver) should work with resolvconf.

openresolv ships with subscribers for dnsmasq (8) and named (8) which handle resolv.conf a bit differently. If they handle search AND domain options then the nameservers listed with the domain are only used when querying for that domain.

Example

# resolv.conf from bge0
search foo.com
nameserver 1.2.3.4

# resolv.conf from tap0
domain bar.org
nameserver 5.6.7.8

In this instance, nameserver 5.6.7.8 will only handle requests for bar.org and nameserver 1.2.3.4 will handle everything else.

Subscribers that need to know only when the resolver configuration file has changed should install a script in %%PREFIX%%/etc/resolvconf/update-libc.d/ rather than in %%PREFIX%%/etc/resolvconf/update.d/. (This is important for synchronization purposes: scripts in update-libc.d/ are run after resolv.conf has been updated; the same is not necessarily true of scripts in update.d/.)

-a INTERFACE Add or overwrite the record for network interface INTERFACE. When this option is used the information must be provided to resolvconf on its standard input in the format of the resolv.conf (5) file. Each line in the file must be terminated by a newline.

-d INTERFACE Delete the record for network interface INTERFACE.

The INTERFACE name may not contain spaces, slashes, asterisks or initial dots, hyphens or tildes.

Following the addition or deletion of the record, resolvconf runs the update scripts as described in the CLIENTS section.

-u Just run the update scripts.

-l PATTERN List the resolv.conf files for the interfaces that match the pattern, otherwise all the interfaces.

-i PATTERN List the interfaces that match the pattern otherwise all the interfaces.

-v PATTERN Echo variables NEWDOMAIN, NEWSEARCH and NEWNS to the console.

%%PREFIX%%/etc/resolvconf/run This is either a directory where nameserver information can be stored or a symbolic link to such a directory. Clients should not make any assumptions about the canonical location of this directory or the hierarchy that is constructed under it.

%%PREFIX%%/etc/resolvconf/interface-order Determines the order in which nameserver information records are processed by resolvconf -l.

%%PREFIX%%/etc/resolvconf/resolv.conf.d/base File containing basic resolver information. The lines in this file are included in the resolver configuration file even when no interfaces are configured.

%%PREFIX%%/etc/resolvconf/resolv.conf.d/head File to be prepended to the dynamically generated resolver configuration file. Normally this is just a comment line.

%%PREFIX%%/etc/resolvconf/resolv.conf.d/tail File to be appended to the dynamically generated resolver configuration file. To append nothing, make this an empty file.

Currently resolvconf does not check the sanity of the information provided to it. Written by Roy Marples <roy@marples.name>.

Heavily based on Debians resolvconf by Thomas Hood <jdthood_AT_yahoo.co.uk>

Copyright \(co 2007 Roy Marples resolv.conf (5), resolver (3).