Comments on: Unix scripts: basic arithmetic operations

By: Unix scripts: how to sum numbers up | Network Solution – Linux – windows – centos- security- cpanel – plesk -directadmin helm

Mon, 12 Dec 2011 05:59:42 +0000

[...] my Basic arithmetic operations in Unix shell post last year, I've shown you how to sum up two [...]

mingxi — Tue, 18 Jan 2011 17:11:59 +0000

I tried the double bracket assignments but it doesn't work. On my machine it will complain :

test: =: unary operator expected

for the line:

test = $(( $i – $j))

Still don't know what is wrong. But thanks for the explanation!

neha — Fri, 25 Jun 2010 11:38:39 +0000

Thanks a lot !! that was really very helpful

Gleb Reys — Thu, 26 Feb 2009 14:43:46 +0000

Hi Bruce, I hope the above like (comment #7) answers your question.

Unix scripts: how to sum numbers up | UNIX Tutorial: Learn UNIX — Wed, 25 Feb 2009 15:33:55 +0000

[...] my Basic arithmetic operations in Unix shell post last year, I've shown you how to sum up two [...]

Bruce Chase — Tue, 24 Feb 2009 19:47:41 +0000

what would the expression look like if you wanted to add a long list of number?

Gleb Reys — Tue, 10 Feb 2009 22:44:39 +0000

Glad to have helped, Chima!

Chima — Tue, 10 Feb 2009 17:58:29 +0000

Thanks a lot. GOd Bless you.

Thu, 18 Sep 2008 00:43:11 +0000

[...] Basic Arithmetic Operations post I've shown you how expression evaluation can be used to calculate simple math expressions in your [...]

Nails Carmody — Tue, 16 Sep 2008 06:24:11 +0000

Hi:

An equivalent way of perform this statement:

ELAPSED=$(($FINISH – $START))

with bash/ksh is using the let keyword:

let ELAPSED="FINISH – START"

It's a personal choice, but most shell programmers tend to use the method you intially introduced.

You can also set expression entirely withn parenthesis and elimiante some $

((ELAPSED=FINISH – START))

Again, it's personal preference

Finally, in shell programming, it's typical to have to increase/decrease a counter – say by 1. this works:

cnt=0
((cnt=cnt+1))
echo $cnt # should equal 1

alternatively, similar to "C" you could do this:

cnt=0
((cnt+=1))

Just thought you'd like to know.