etcresolvconf

etcresolvconf is the resolvconf configuration framework used on many Unix-like systems to manage the system’s DNS resolver information. It is implemented by the resolvconf package and provides a centralized mechanism to generate the contents of /etc/resolv.conf from multiple sources, such as DHCP clients, VPN connections, and local configuration.

The framework relies on a directory of templates and sources, typically under /etc/resolvconf/resolv.conf.d. Common template files include head (lines placed before any nameserver entries), base (static options that apply to all configurations), and tail (lines appended after the nameserver entries). As network information changes, resolvconf combines these blocks with data supplied by various network services to produce the final resolver configuration.

Operation and usage: When network conditions change or when a user runs the resolvconf utility, the system regenerates the resolver file. The primary command is resolvconf, with common invocations such as resolvconf -u to update the configuration and resolvconf -l to list sources. The resulting resolver data is typically written to /etc/resolv.conf, though on some systems it may be placed under a run-time path (for example, /run/resolvconf/resolv.conf) and/or exposed via a symlink. Root privileges are required to modify /etc/resolv.conf.

Relation to other components: resolvconf and its etc/resolvconf infrastructure are often used in conjunction with DHCP clients, VPN software, and NetworkManager. On systems that rely on systemd-resolved or other modern resolvers, resolvconf may be used alongside or avoided depending on the distribution’s configuration. Potential conflicts can arise if multiple services attempt to write to the resolver configuration, so proper integration and ordering are important.

See also: /etc/resolv.conf, resolvconf, DNS, DHCP, NetworkManager, systemd-resolved.