Host name bus mechanism
systemd-hostnamed.service
/lib/systemd/systemd-hostnamed
systemd-hostnamed is a system service that may be used as a mechanism to change the system's hostname. systemd-hostnamed is automatically activated on request and terminates itself when it is unused.
The tool hostnamectl(1) is a command-line client to this service.
See the \m[blue]developer documentation\m[]\s-2\u[1]\d\s+2 for information about the APIs systemd-hostnamed provides.
developer documentation
http://www.freedesktop.org/wiki/Software/systemd/hostnamed