From the original Amiga UNIX 2.1 manual. Some things it mentions may not be in this release.
NAME
gethostid - get unique identifier of current host
SYNOPSIS
cc [ flag... ] file ... -lucbgethostid()
DESCRIPTION
gethostid returns the 32-bit identifier for the current host, which should be unique across all hosts. This number is usually taken from the CPU board's ID PROM.