prompt for yes

_is_y.sh

#!/bin/bash

echo -n "Continue (y/n)? "
read answer

if [ "$answer" != "${answer#[Yy]}" ] ;then
    echo Yes
    install_thing
else
    echo No
    exit
fi

_is_yes.sh

#!/bin/bash

echo -n "Must be yes or Yes (yes)? "
read answer

if [ "$answer" != "${answer#[Yy]es}" ] ;then
    echo Yes
    install_thing
else
    echo No
    exit
fi