gethostid.3: Before version 2.2, glibc stored the host ID in /var/adm/hostid

Also: rewrite some text describing the /etc/hostid file, so that
this location is referred to just once on the page.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man3/gethostid.3

@@ -60,11 +60,6 @@ and thus usually never needs to be set.
 The
 .BR sethostid ()
 call is restricted to the superuser.
-
-The
-.I hostid
-argument is stored in the file
-.IR /etc/hostid .
 .SH "RETURN VALUE"
 .BR gethostid ()
 returns the 32-bit identifier for the current host as set by
@@ -86,8 +81,6 @@ to store the host ID.
 .B EPERM
 The calling process's effective user or group ID is not the same
 as its corresponding real ID.
-.SH FILES
-.I /etc/hostid
 .SH "CONFORMING TO"
 4.2BSD; these functions were dropped in 4.4BSD.
 SVr4 includes
@@ -99,10 +92,18 @@ POSIX.1-2001 specifies
 but not
 .BR sethostid ().
 .SH NOTES
+In the glibc implementation, the
+.I hostid
+is stored in the file
+.IR /etc/hostid .
+(In glibc versions before 2.2, the file
+.I /var/adm/hostid
+was used.)
+.\" libc5 used /etc/hostid; libc4 didn't have these functions
+
 In the glibc implementation, if
 .BR gethostid ()
-cannot open
-.IR /etc/hostid ,
+cannot open the file containing the host ID,
 then it obtains the hostname using
 .BR gethostname (2),
 passes that hostname to