Why am I not getting the result of the addition?

Question

I have written the following script file from my book.

a=2
b=3 
c=$[a+b]
echo 'The result is:' $c

After executing this program, instead of getting 5, I am getting output as:

The result is: $[a+b]

It should work in bash. Try putting #!/bin/bash at the start of your script. — Jos, Aug 9, 2014 at 18:46
@Jos try it :) I thought so too... It is now depreciated, and so i guess that is why it wouldn't work... stackoverflow.com/questions/6348902/… — Tim, Aug 9, 2014 at 18:47
@Jos Event after adding the quoted string at the start, the output remained the same. — Mistu4u, Aug 9, 2014 at 18:50
@Jos, oh so it does, miss type... OP: Are you doing this in a bash script or a terminal? — Tim, Aug 9, 2014 at 18:50

Tim · Accepted Answer · 2014-08-09 18:54:25Z

1

You shouldn't be using []:

Go for this (with the (()) brackets:

a=2
b=3
c=$((a+b))
echo 'The result is:' $c

returns:

The result is: 5

answered Aug 9, 2014 at 18:47

Tim

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