Re: bin/53458: usr.sbin/ypserv/ypinit: error while checking hostname

[Robert Elz <kre%munnari.OZ.AU@localhost>]

The following reply was made to PR bin/53458; it has been noted by GNATS.

From: Robert Elz <kre%munnari.OZ.AU@localhost>
To: =?UTF-8?Q?Fr=C3=A9d=C3=A9ric_Fauberteau?= <triaxx%NetBSD.org@localhost>
Cc: gnats-bugs%NetBSD.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost,
        Martin Husemann <martin%duskware.de@localhost>, christos%zoulas.com@localhost
Subject: Re: bin/53458: usr.sbin/ypserv/ypinit: error while checking hostname
Date: Fri, 20 Jul 2018 19:41:27 +0700

     Date:        Fri, 20 Jul 2018 12:53:41 +0200
     From:        =?UTF-8?Q?Fr=C3=A9d=C3=A9ric_Fauberteau?= <triaxx%NetBSD.org@localhost>
     Message-ID:  <3a0d2be66f8647ce8f31645ae18e72b9%NetBSD.org@localhost>
 
   | I don't really understand why the following script:
   | #!/bin/sh
   | HOSTNAME=foo
   | echo ${HOSTNAME}
   |
   | produces the following output:
   | defiler.triaxx.org
 
 You are running into a feature of the NetBSD shell, ${HOSTNAME} is a built
 in variable, that always expands to (effectively the same as) $(/bin/hostname)
 (It doesn't matter what is assigned to it, that is ignored ... though I guess 
 there is some argument to change that).
 
 This is documented in sh(1) ...
 
      HOSTNAME   Set to the current hostname of the system, as returned by
                 gethostname(3).  This is obtained each time HOSTNAME is
                 expanded, so changes to the system's name are reflected
                 without further action.  If unset, it returns nothing.
                 Setting it does nothing except reverse the effect of an
                 earlier unset.
 
 It is intended (mostly) for use in PS1 (and similar places), often as 
 ${HOSTNAME%%.*}
 
 kre