Yes/Noを問い合わせる

readで読み込みcaseで判断する

#!/bin/sh
#yesno.sh

yesno(){
    yn_result=""
    while [ -z "$yn_result" ]; do
        read yn_reply
        case "$yn_reply" in
            [yY][eE][sS])
                yn_result=0;;
            [nN][oO])
                yn_result=1;;
            *)
                echo "Please enter YES or NO.";;
        esac
    done
    return $yn_result
}

echo "Do you love icecream?"
if yesno; then
    echo "Okey, you love icecream."
else
    echo "So you don't like icecream..."
fi

echo "Are you female?"
if yesno; then
    echo "Hum, you looks so cute!"
else
    echo "You must be male."
fi

$ ./yesno.sh 
Do you love icecream?
yes
Okey, you love icecream.
Are you female?
no
You must be male.