echo "Enter a number"
read number
echo "What do you want to do to this number?"
echo "Enter d, to count down to zero"
echo "Enter u, to count  up from zero"
read choice
case $choice in
d) while [ "$number" -ge 0 ]
do
echo $number
number=`expr $number - 1`      # no spaces here before/after = sign
done;;
u) while [ 0 -le "$number" ]
do
echo $number
number=`expr $number + 1`
done;;
esac
echo "bye"
~