hostname — Local hostname configuration file
/etc/hostname
The /etc/hostname file configures the
name of the local system that is set during boot using the
sethostname(2)
system call. It should contain a single newline-terminated
hostname string. Comments (lines starting with a `#') are ignored.
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.
You may use hostnamectl(1) to change the value of this file during runtime from the command line. Use systemd-firstboot(1) to initialize it on mounted (but not booted) system images.