RESOLVCONF(8)

NAME
resolvconf - manage nameserver information

SYNOPSIS
cat FILE | resolvconf -a INTERFACE

resolvconf -d INTERFACE

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

SERVERS
Normally resolvconf is run only by hook scripts attached to network interface configurers such as pppd(8) (for ppp interfaces), to DHCP clients such as dhclient3(8), to ifup(8) and ifdown, 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.

CLIENTS
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 /etc/resolvconf/update.d/. 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 GNU C Library resolver(3). When nameserver information is updated the script /etc/resolvconf/update.d/libc writes a new resolver configuration file to /etc/resolvconf/run/resolv.conf and then runs the scripts in /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 /etc/resolvconf/run/resolv.conf. This link is never modified by /sbin/resolvconf. If you find that /etc/resolv.conf is not being updated, check to see that the link is intact.

The GNU 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 GNU C Library resolver) should work with resolvconf.

Subscribers that need to know only when the resolver configuration file has changed should install a script in /etc/resolvconf/update-libc.d/ rather than in /etc/resolvconf/update.d/. Examples of packages that do this are fetchmail(1) and squid(8).

Hook scripts will find the files containing nameserver information in the current directory.

OPTIONS

-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 or initial dots or tildes.

FILES

/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.

/etc/resolvconf/interface-order
    Determines the order in which nameserver information records are processed. See interface-order(5).

/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.

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

/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.

BUGS
Currently resolvconf does not check the sanity of the information provided to it.

AUTHOR
Written by Thomas Hood <jdthood@yahoo.co.uk>.

COPYRIGHT
Copyright © 2004 Thomas Hood
This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

SEE ALSO
interface-order(5), resolv.conf(5), resolver(3).