Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!ukc!mucs!cns!jf
From: jf@ap.co.umist.ac.uk (John Forrest)
Newsgroups: comp.sys.apollo
Subject: Re: internet address
Message-ID: <1991Mar2.173314.9590@cns.umist.ac.uk>
Date: 2 Mar 91 17:33:14 GMT
References: <9102261044.AA02546@apo.esiee.fr> <5011a909.20b6d@apollo.HP.COM>
Sender: news@cns.umist.ac.uk (Usenet news)
Organization: comp
Lines: 48

In article <5011a909.20b6d@apollo.HP.COM> ced@apollo.HP.COM (Carl Davidson) writes:
>From article <9102261044.AA02546@apo.esiee.fr>, by bonnetf@apo.esiee.fr (bonnet-franck):
>> Hi,
>>
>> Does somebody knows how to get the internet address of a machine
>> when I am working on it ( whithout looking in /etc/hosts ) ?
>>
>
>I use a shell command:
>
>       % /etc/ping `/etc/hostname` 64 1
>
>which says:
>
>       ping the host I'm logged into once, with a 64 byte packet.
>
>If you need to get just the Internet address, you can extract it from the
>with your favorite test reprocessor, i.e. sed, awk, perl,...
>
I suddenly found myself needing a unique number for each
workstation, and the Internet address seemed more portably than
trying to discover how to get hold of the Apollo node id.
Anyway, based on what I said before, gethostid(2) and/or
hostid(1) seem the easiest way. Unfortunately on our OS10.1
systems you actually have to set this up (probably latter
versions as well) by adding:

        hostid `hostname`

to /etc/rc.local (preferably at the end once BIND and
everything are working ok). Having done this, you can simply
invoke:

        hostid

from a shell script, or use:

        extern long gethostid(void)

from a program. Easy isn't it, with no need of network usage
nor sed/awk/perl scripts. Of course, hostid does return a hex
value, so if you want it in some otherform, you had best write
a program that invokes gethostid and prints out the value in
the style you want.

John Forrest
Dept of Computation
UMIST