Some simple argument handling for use in shell scripts. HT to an answer on StackOverflow.

params.sh

#! /bin/sh -

#argument defaults
x="foo"
y="bar"

# argument handling
while test $# -gt 0
do
    case "$1" in
        -s) x=${2}
			echo "x set to: " ${2}
            ;;
        -p) y=${2}
			echo "y set to: " ${2}
            ;;
        -*) echo "bad option $1"
            ;;
        *) #ignore
            ;;
    esac
    shift
done

# inform if defaults will be used
if [ "${x}" = "foo" ]; then
	echo "No x supplied. Default x will be used: " ${x}
fi

if [ "${y}" = "bar" ]; then
	echo "No y supplied. Default y will be used: " ${y}
fi