Как давний системный администратор * nix, я заявлю очевидное, без прямой ссылки на RTFM: :)
hostnamectl may be used to query and change the system hostname and
related settings.
This tool distinguishes three different hostnames: the high-level
"pretty" hostname which might include all kinds of special characters
(e.g. "Lennart's Laptop"), the static hostname which is used to
initialize the kernel hostname at boot (e.g. "lennarts-laptop"), and
the transient hostname which is a fallback value received from network
configuration. If a static hostname is set, and is valid (something
other than localhost), then the transient hostname is not used.
Note that the pretty hostname has little restrictions on the characters
used, while the static and transient hostnames are limited to the
usually accepted characters of Internet domain names.
The static hostname is stored in /etc/hostname, see hostname(5) for
more information. The pretty hostname, chassis type, and icon name are
stored in /etc/machine-info, see machine-info(5).
Это верно для большинства дистрибутивов "linux".
- mem