UNIX for Dummies Questions & Answers

function calculator()
{
firstN=$1
secondN=$3
result=0
operator=$2
 while [ $# -eq 3 ]
 do
  if [ "$operator" = * ]
   then
   $operator=\*
   fi

  result=$(( $firstN $operator $secondN ))
  echo "$result"
  return $result
 done
 echo "Usage: $0 number operator number"
 exit 1
 return
}

calculator $1 $2 $3

function calculator
{
typeset -i result
firstN=$1
operator=$2
secondN=$3
if [ $# -ne 3 ]; then
 echo "Usage: $0 number operator number"
 exit 1
fi
result=${firstN}${operator}${secondN}
echo "$result"
}
set -f
calculator $1 $2 $3

set -- A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
echo "Total = "$#
echo "All = "$@
echo "1  = "$1
echo "11 = "$11
echo "11 = "${11}

man typeset
man set

$ function fn_evaluate { perl -e 'print eval shift' "$*"; }
$ read query
6 * 7
$ result=$(fn_evaluate "$query")
$ echo $result
42

#!/bin/bash

function calculator()
{
firstN="$1"
secondN="$3"
result=0
operator="$2"

 while [ $# -eq 3 ]
 do
  if [ "$operator" = "*" ]
   then
   operator="\*"
   result=${$firstN} ${operator} ${secondN}
   return
   else
   result=$(( $firstN $operator $secondN ))
   return
  fi
 done

 echo "Usage: $0 number operator number"
 exit 1
 return
}

set -f

calculator "$1" "$2" "$3"
echo $result