GETHOSTID
NAME
gethostid, sethostid - get or set the unique identifier of the current host
SYNOPSIS
#include <unistd.h>
long gethostid(void);
I int sethostid(long hostid );
DESCRIPTION
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
R sethostid ()
call is restricted to the superuser.
The
hostid
argument is stored in the file
R /etc/hostid .
RETURN VALUE
R gethostid ()
returns the 32-bit identifier for the current host as set by
sethostid(2).
FILES
/etc/hostid
CONFORMING TO
4.2BSD; these functions were dropped in 4.4BSD.
SVr4 includes
R gethostid ()
but not
R sethostid ().
POSIX.1-2001 specifies
R gethostid ()
but not
R sethostid ().
NOTES
In the glibc implementation, if
R gethostid ()
cannot open
R /etc/hostid ,
then it obtains the host name using
gethostname(2),
passes that host name to
gethostbyname_r(3)
in order to obtain the host's IPv4 address,
and returns a value obtained by bit-twiddling the IPv4 address.
(This value may not be unique.)
SEE ALSO
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