hostname — Local hostname configuration file
/etc/hostname file configures the
name of the local system that is set during boot using the
system call. It should contain a single newline-terminated
hostname string. The hostname may be a free-form string up to 64
characters in length; however, it is recommended that it consists
only of 7-bit ASCII lower-case characters and no spaces or dots,
and limits itself to the format allowed for DNS domain name
labels, even though this is not a strict requirement.
Depending on the operating system, other configuration files might be checked for configuration of the hostname as well, however only as fallback.
The simple configuration file format of
/etc/hostname originates from Debian