hostnamectl(1) man page — Describes hostnamectl including the commands and command options.

hostname(1) man page — Contains an explanation of the hostname and domainname commands.

hostname(5) man page — Contains an explanation of the host name file, its contents, and use.

hostname(7) man page — Contains an explanation of host name resolution.

machine-info(5) man page — Describes the local machine information file and the environment variables it contains.

machine-id(5) man page — Describes the local machine ID configuration file.

systemd-hostnamed.service(8) man page — Describes the systemd-hostnamed system service used by hostnamectl.