shell函数的使用，与其他语言用法相同

#!/bin/sh

yes_or_no(){
	echo "Is your name $* ?"
	while true
	do
		echo -n "Enter yes or no: "
		read x
		case "$x" in
			y ? yes ) return 0;;
			n ? no  ) return 1;;
		    * )       echo "Answer yes or no"
		esac
	done
}

echo "Original parameters are $*"

if yes_or_no "$1"
then
	echo "Hi $1, nice name"
else
	echo "Never mind"
fi
exit 0

Original parameters are 
Is your name  ?
Enter yes or no: yes
Hi , nice name