$ Linux Command

Network

domainname

Show or set the NIS/YP domain name.

nisdomainnetworkhostname

Additional Notes

domainname displays or sets the NIS (Network Information Service, formerly YP) domain name of the current system. The NIS domain name is different from the DNS domain name and is used for NIS client-server communication to identify the administrative domain.

Without arguments, domainname prints the current NIS domain name. With an argument, it sets the domain name. The NIS domain name is typically configured in /etc/defaultdomain or set during system startup. It is often used in conjunction with ypbind, ypserv, and related NIS tools.

Syntax

domainname [nis-domain]

Parameters

  • nis-domain: The NIS domain name to set. If omitted, the current domain name is displayed.

Common Options

  • -F, --file file: Read the domain name from a file instead of the command-line argument.
  • -h, --help: Show help text.
  • -V, --version: Show version information.

Examples

domainname

Show the current NIS domain name.

sudo domainname mydomain

Set the NIS domain name to mydomain (requires root).

sudo domainname -F /etc/defaultdomain

Set the NIS domain name from the contents of a file.

Practical Notes

  • The NIS domain name is not the same as the DNS domain name shown by dnsdomainname or hostname -d.
  • Setting the NIS domain name is required before starting NIS services.
  • The domain name set with domainname is lost after reboot unless stored in a configuration file such as /etc/defaultdomain or /etc/sysconfig/network.
  • Many systems use systemd's nss-myhostname or similar and do not require NIS; in those cases domainname returns (none).