#!/bin/sh 

# This script is an example of using the "expr" command, illustrating both
# arithmetic calculations and comparisons, as well as lexicographic
# comparisons on words


numpattern="\b[1-9][0-9]*\b"

echo "Please enter first number (or word, for lexicographic comparisons)"
read num1

echo "Please enter second number (or word, for lexicographic comparisons)"
read num2

if [ `expr $num1 : $numpattern` != "0" ] && [ `expr $num2 : $numpattern` != "0" ]
then
  echo "Arithmetic:"
  echo "-----------------------"
  echo "$num1 + $num2 =" `expr $num1 + $num2`
  echo "$num1 - $num2 =" `expr $num1 - $num2`
  echo "$num1 * $num2 =" `expr $num1 \* $num2`
  echo "$num1 / $num2 =" `expr $num1 / $num2` "  (quotient)"
  echo "$num1 % $num2 =" `expr $num1 % $num2` "  (remainder)"
fi

echo ""

echo "Comparisons:"
echo "-----------------------"
echo "Note: 0 means false, 1 means true"
echo ""
echo "$num1 = $num2 is " `expr $num1 = $num2`
echo "$num1 != $num2 is " `expr $num1 != $num2`
echo "$num1 < $num2 is " `expr $num1 \< $num2`
echo "$num1 > $num2 is " `expr $num1 \> $num2`
echo "$num1 <= $num2 is " `expr $num1 \<= $num2`
echo "$num1 >= $num2 is " `expr $num1 \>= $num2`