GETHOSTID(2) Linux Programmer's Manual GETHOSTID(2)
gethostid, sethostid - get or set the unique identifier of the current
int sethostid(long hostid);
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
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.
Linux 0.99.13 1993-11-29 GETHOSTID(2)