Date: Wed, 20 Feb 2002 23:18:59 +0100 From: Cliff Sarginson <csfbsd@raggedclown.net> To: questions@freebsd.org Subject: Re: BASH programming question Message-ID: <20020220221859.GA2006@raggedclown.net> In-Reply-To: <5.1.0.14.2.20020220160637.02763050@pop.earthlink.net> References: <5.1.0.14.2.20020220160637.02763050@pop.earthlink.net>
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On Wed, Feb 20, 2002 at 04:17:57PM -0500, B.K. DeLong wrote:
> Hey all -
>
> I'm somewhat new to the world of BASH scripting. I'm trying to write a
> script that I can throw in cron to check if my IP has changed. However, I'm
> having problems with the variable. What I'm trying to say, is "if $IP is
> not null then email me"
>
> ie. if diff produces no results, then the IP is the same.
>
> However, I can't quite figure out the way to define this without getting a
> "too many arguments" error.
>
> #!/usr/local/bin/bash -x
> ifconfig | grep "inet " | cut -f2 -d" " | grep 24. > /.newip
> IP='diff /.newip /.currentip'
Your quotes are the wrong way around..
You need
`
not
'
And "not equal to" is "!=" and ... "null" , is that built into bash ?
I think not, try "".
Also you should get into the habit of using $ vars in {} to
avoid errors if they have a NULL value, i.e.
${IP}
Also the "cool" way to do this is to actually check the exit code
from diff "$?", if it is zero then no differences were found.
--
Regards
Cliff Sarginson -- <csfbsd@raggedclown.net>
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