Section: Linux Programmer's Manual (1)
hostname - show or set the system's host name
domainname - show or set the system's NIS/YP domain name
ypdomainname - show or set the system's NIS/YP domain name
nisdomainname - show or set the system's NIS/YP domain name
dnsdomainname - show the system's DNS domain name
hostname [-a|--alias] [-d|--domain] [-f|--fqdn|--long] [-A|--all-fqdns] [-i|--ip-address] [-I|--all-ip-addresses] [-s|--short] [-y|--yp|--nis]
hostname [-b|--boot] [-F|--file filename] [hostname]
hostname [-h|--help] [-V|--version]
domainname [nisdomain] [-F file]
ypdomainname [nisdomain] [-F file]
nisdomainname [nisdomain] [-F file]
Hostname is used to display the system's DNS name, and to display or set its hostname or NIS domain name.
When called without any arguments, the program displays the current names:
dnsdomainname will print the domain part of the FQDN (Fully Qualified Domain Name). The complete FQDN of the system is returned with hostname --fqdn (but see the warnings in section THE FQDN below).
When called with one argument or with the --file option, the commands set the host name or the NIS/YP domain name. hostname uses the sethostname?(2) function, while all of the three domainname, ypdomainname and nisdomainname use setdomainname?(2). Note, that this is effective only until the next reboot. Edit /etc/hostname for permanent change.
Note, that only the super-user can change the names.
It is not possible to set the FQDN or the DNS domain name with the dnsdomainname command (see THE FQDN below).
The host name is usually set once at system startup in /etc/init.d/hostname.sh (normally by reading the contents of a file which contains the host name, e.g. /etc/hostname).
The FQDN (Fully Qualified Domain Name) of the system is the name that the resolver?(3) returns for the host name, such as, ursula.example.com. It is usually the hostname followed by the DNS domain name (the part after the first dot). You can check the FQDN using hostname --fqdn or the domain name using dnsdomainname.
You cannot change the FQDN with hostname or dnsdomainname.
The recommended method of setting the FQDN is to make the hostname be an alias for the fully qualified name using /etc/hosts, DNS, or NIS. For example, if the hostname was "ursula", one might have a line in /etc/hosts which reads
Therefore it depends on the configuration of the resolver (usually in /etc/host.conf) how you can change it. Usually the hosts file is parsed before DNS or NIS, so it is most common to change the FQDN in /etc/hosts.
If a machine has multiple network interfaces/addresses or is used in a mobile environment, then it may either have multiple FQDNs/domain names or none at all. Therefore avoid using hostname --fqdn, hostname --domain and dnsdomainname. hostname --ip-address is subject to the same limitations so it should be avoided as well.
The address families hostname tries when looking up the FQDN, aliases and network addresses of the host are determined by the configuration of your resolver. For instance, on GNU Libc systems, the resolver can be instructed to try IPv6 lookups first by using the inet6 option in /etc/resolv.conf.
/etc/hostname Historically this file was supposed to only contain the hostname and not the full canonical FQDN. Nowadays most software is able to cope with a full FQDN here. This file is read at boot time by the system initialization scripts to set the hostname.
Peter Tobias, <firstname.lastname@example.org>
Bernd Eckenfels, <email@example.com> (NIS and manpage).
Michael Meskes, <firstname.lastname@example.org>
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