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From: rearl@gnu.ai.mit.edu (Robert Earl)
Newsgroups: comp.unix.questions
Subject: Re: Bourne shell question
Summary: expr(1)
Message-ID: <REARL.91May9005239@mole.gnu.ai.mit.edu>
Date: 9 May 91 04:52:39 GMT
References: <1991May8.192623.24160@bnlux1.bnl.gov>
Sender: news@ai.mit.edu
Organization: (EVIL!)
Lines: 25
In-reply-to: abrams@dan.ccd.bnl.gov's message of 8 May 91 19:26:23 GMT

In article <1991May8.192623.24160@bnlux1.bnl.gov> abrams@dan.ccd.bnl.gov (The Ancient Programmer) writes:

|	   How does one do a simple computation in a shell script?
|   The c-shell does it very neatly. 
|   Running:
|	   #!/bin/csh
|	   set a = 10
|	   set b = 1
|	   @ c = $a - $b
|	   echo "a=$a, b=$b, c=$c"
|
|   produces: a=10, b=1, c=9
|
|   but I've been unable to find out how to do this in the bourne shell.

You have to use expr(1) and backquotes:

	#!/bin/sh
	a=10
	b=1
	c=`expr $a - $b`		# or perl -e "print $a - $b" :-)
	echo "a=$a, b=$b, c=$c"


--robert