shell 判断键盘输入

#!/bin/bash
echo "Hit a key, then hit return."
read Keypress
case "$Keypress" in
 [A-Z] ) echo "Uppercase letter";;
 [a-z] ) echo "Lowercase letter";;
 [0-9] ) echo "Digit";;
 * ) echo "Punctuation, whitespace, or other";;
esac