Shell Programming and Scripting

echo $A
123-ABC.def

echo $A | wc -c
      12

echo $A | sed 's/[[:alnum:].-]//g'| wc -c
       1

while true; do
  echo -n "Enter your favorite string: "
  read n
  case $n in
    ?????????????*) echo "Must be less than 12 characters";;
    '') echo "Must not be empty";;
    *[!A-Za-z0-9. -]*) echo "Must only contain letters, numbers, periods, spaces, and dashes";;
    *) break;;
  esac
  echo Try again.
done

${#A}