Shell Programming and Scripting

./abc.sh a b c d 
 
in above calling 
a is called at no. 1 position
b is at no 2 
c is at no 3 
d is at no 4

pos=1
for arg in "$@"
do
if [[ ${arg} == "-st" ]]
then
echo "abc"
echo ${pos}
parameter=$((${pos}+1))
echo $parameter
        if [[ $parameter == "" ]]
                then
                        echo "please enter date"
                fi
fi
pos=$((${pos}+1))
done
~
~
 
 
./abc.sh a b c -st 
 
then output is 
abc
4
5

 
y it is not printing the "please enter date as i have not entered fifth positional parameter"

 if [[ $parameter == "" ]]

if [[ $pos == $# ]]