Get or set a unique 32-bit identifier for the current machine. The 32-bit identifier is intended to be unique among all UNIX systems in existence. This normally resembles the Internet address for the local machine, as returned by gethostbyname(3), and thus usually never needs to be set.
The sethostid call is restricted to the superuser.
The hostid argument is stored in the file /etc/hostid.
gethostid returns the 32-bit identifier for the current host as set by sethostid(2).
4.2BSD. These functions were dropped in 4.4BSD. POSIX.1 does not define these functions, but ISO/IEC 9945-1:1990 mentions them in B.4.4.1. SVr4 includes gethostid but not sethostid.