~$ man имя хоста
[…]
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
127.0.1.1 ursula.example.com ursula
Technically: The FQDN is the name getaddrinfo(3) returns for the host name returned by gethostname(2). The DNS domain name is
the part after the first dot.
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.
[…]
На это любезно указал poige в другой ветке , и это именно то, что Лутц предложил здесь.
Вы не должны вводить свое полное доменное имя в /etc/hostname
.