-.\" Hey Emacs! This file is -*- nroff -*- source.
-.\"
.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
.\"
+.\" Updated with additions from Mitchum DSouza <m.dsouza@mrc-apu.cam.ac.uk>
+.\" Portions Copyright 1993 Mitchum DSouza <m.dsouza@mrc-apu.cam.ac.uk>
+.\"
+.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
-.\"
-.\" Updated with additions from Mitchum DSouza <m.dsouza@mrc-apu.cam.ac.uk>
-.\" Portions Copyright 1993 Mitchum DSouza <m.dsouza@mrc-apu.cam.ac.uk>
+.\" %%%LICENSE_END
.\"
.\" Modified Tue Oct 22 00:22:35 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
-.TH GETHOSTID 3 2010-09-20 "Linux" "Linux Programmer's Manual"
+.TH GETHOSTID 3 2017-09-15 "Linux" "Linux Programmer's Manual"
.SH NAME
gethostid, sethostid \- get or set the unique identifier of the current host
.SH SYNOPSIS
.B #include <unistd.h>
-.sp
+.PP
.B long gethostid(void);
.br
.BI "int sethostid(long " hostid );
-.sp
+.PP
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
-.sp
+.PP
.ad l
.br
.BR gethostid ():
.RS 4
-_BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
-_XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
+_BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500
+.\" || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
.RE
.BR sethostid ():
-.RS 4
-_BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE\ <\ 500)
-.RE
+.nf
+ Since glibc 2.21:
+.\" commit 266865c0e7b79d4196e2cc393693463f03c90bd8
+ _DEFAULT_SOURCE
+ In glibc 2.19 and 2.20:
+ _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE\ <\ 500)
+ Up to and including glibc 2.19:
+ _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE\ <\ 500)
+.fi
.ad b
.SH DESCRIPTION
.BR gethostid ()
machine, as returned by
.BR gethostbyname (3),
and thus usually never needs to be set.
-
+.PP
The
.BR sethostid ()
call is restricted to the superuser.
.BR gethostid ()
returns the 32-bit identifier for the current host as set by
.BR sethostid ().
-
+.PP
On success,
.BR sethostid ()
returns 0; on error, \-1 is returned, and
.B EPERM
The calling process's effective user or group ID is not the same
as its corresponding real ID.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbw25
+l l l.
+Interface Attribute Value
+T{
+.BR gethostid ()
+T} Thread safety MT-Safe hostid env locale
+T{
+.BR sethostid ()
+T} Thread safety MT-Unsafe const:hostid
+.TE
+.sp 1
.SH CONFORMING TO
4.2BSD; these functions were dropped in 4.4BSD.
SVr4 includes
.BR gethostid ()
but not
.BR sethostid ().
-POSIX.1-2001 specifies
+.PP
+POSIX.1-2001 and POSIX.1-2008 specify
.BR gethostid ()
but not
.BR sethostid ().
.I /var/adm/hostid
was used.)
.\" libc5 used /etc/hostid; libc4 didn't have these functions
-
+.PP
In the glibc implementation, if
.BR gethostid ()
cannot open the file containing the host ID,