product of two input variable in shell
<p>The program works fine in case " + " ," - "," /"</p>

<p>Example : </p>

<pre><code>./calculate.sh 1 + 2 ==&gt; output is 3.
</code></pre>

<p>But the problem here is when I type : </p>

<pre><code>./calculate.sh 1 * 2 ==&gt;output is "Please ..."
</code></pre>

<p>I've tried <code>"\*"</code> like this but it seem the variable $2 can not get what I want.</p>

<p>Anyone can help me what is the problem here ? </p>

<pre><code>#!/bin/sh
if [ $# -ne 3 ]
 then
      echo "Please input a number , an operator + or - or * or /"
 else
      case "$2" in 
            "+") echo "Sum is `expr $1 + $3`";;
            "-") echo "Substraction is `expr $1 - $3`";;
            "*") echo "Product is `expr $1 \* $3`";;
            "/") echo "Division is `expr $1 / $3`";;
      esac
fi
</code></pre>