#!/bin/bash
Function addem
{
If [ $# -eq 0 ] || [ $# -gt 2 ]
then
 echo -1
elif [ $# -eq 1 ]
then
 echo $[ $1 + $1 ]
else
 echo $[ $1 + $2 ]
fi
}
echo –n “adding 10 and 15:”
value=$(addem 10 15)
echo $value