While loop

while test-commands ; do
    consequent-commands
done

Example

echo Format A: [Y]es, [N]o, [M]aybe?
while read i; do
    case $i in
	y | Y)
	    result=Y
	    break;;
	n | N)
	    result=N
	    break;;
	m | M)
	    result=M
	    break;;
	*)
	    echo Format A: [Y]es, [N]o, [M]aybe?
    esac
done
echo You typed $result.