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Date:      Thu, 14 Aug 2003 13:01:26 -0500
From:      Dan Nelson <dnelson@allantgroup.com>
To:        Richard Tobin <richard@cogsci.ed.ac.uk>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: Using bc in bash script
Message-ID:  <20030814180126.GB33379@dan.emsphone.com>
In-Reply-To: <200308141742.SAA17915@rhymer.cogsci.ed.ac.uk>
References:  <200308141742.SAA17915@rhymer.cogsci.ed.ac.uk>

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In the last episode (Aug 14), Richard Tobin said:
> > I'm trying to calculate the number of seconds between $start_time and
> > $end_time in a bash script.
> 
> Bash has built-in integer arithmetic:
> 
>   et=$[End_time - Start_time]

Most bourne-based shells have arithmetic evaluation.  For portability,
you should use the $(( )) syntax:

/bin/sh
$ echo $(( 1 + 3 ))
4
$

-- 
	Dan Nelson
	dnelson@allantgroup.com



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