From owner-freebsd-questions  Thu Feb 21  1: 6:36 2002
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Date: Thu, 21 Feb 2002 10:06:30 +0100
From: Rogier Steehouder <r.j.s@gmx.net>
To: "B.K. DeLong" <bkdelong@pobox.com>
Cc: freebsd-questions@freebsd.org
Subject: Re: BASH programming question
Message-ID: <20020221100630.A644@localhost>
Mail-Followup-To: Rogier Steehouder <r.j.s@gmx.net>,
	"B.K. DeLong" <bkdelong@pobox.com>, freebsd-questions@freebsd.org
References: <20020221000224.A32489@nigsch.com> <5.1.0.14.2.20020220160637.02763050@pop.earthlink.net> <5.1.0.14.2.20020220160637.02763050@pop.earthlink.net> <20020220224520.A31541@nigsch.com> <5.1.0.14.2.20020220165911.01e189a0@pop.earthlink.net> <20020221000224.A32489@nigsch.com> <20020220231436.GA658@raggedclown.net> <5.1.0.14.2.20020220214132.029df6f0@pop.earthlink.net>
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In-Reply-To: <5.1.0.14.2.20020220214132.029df6f0@pop.earthlink.net>; from bkdelong@pobox.com on Wed, Feb 20, 2002 at 09:43:53PM -0500
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On 20-02-2002 21:43 (-0500), B.K. DeLong wrote:
> Thanks for all your help - here's the finished script. I know the comments 
> are a bit anal but I hate having to look all over the place for the same 
> info again.
> 
> Comments welcome:

Well, don't mind if I do :-)

> #!/usr/local/bin/bash
Why not use plain /bin/sh ? I haven't seen anything bash-specific.

#!/bin/sh
# Having machine-specific variables in front eases migrating later.
IPFILE='/usr/local/bin/.currentip'
SERVERNAME='firewall.internal.brain-stream.com'

> ifconfig xl0 | grep "inet " | cut -f2 -d" " > /usr/local/bin/.newip
NEWIP=$(ifconfig xl0 | grep "inet " | cut -f2 -d" ")
# saves writing a file.

> if diff /usr/local/bin/.newip /usr/local/bin/.currentip; then exit 0;
read OLDIP < ${IPFILE}
if [ ${OLDIP} != ${NEWIP} ]; then
# saves running 1 program: read is an internal command.

> else
>          cat /usr/local/bin/.newip > /usr/local/bin/.currentip;
>          mail -s "New IP for firewall.internal.brain-stream.com " ip  < 
> /usr/local/bin/.currentip;
>          echo "A New IP has been found"
>          exit 0
> fi
	echo ${NEWIP} > ${IPFILE}
	mail -s "New IP for ${SERVERNAME}" ip < ${IPFILE}
	echo 'A New IP has been found'
fi

All in all it uses some extra variables, but saves starting one other
program and only leaves one file behind. If you use DHCP, you can put
all this in /etc/dhclient-exit-hooks and then the new IP is in
${new_ip_address}. That will save running another three programs.

With kind regards, Rogier Steehouder

-- 
                          ___                          _
-O_\                                                  //
 | /               Rogier Steehouder                 //\
/ \                  r.j.s@gmx.net                  //  \
  <---------------------- 25m ---------------------->

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