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案例陈述帮助

tag-icon • tag-icon bash shell-script case
案例陈述帮助

我对 Unix 很陌生，我需要有关此案例陈述的帮助。我想做的是让用户用case语句选择一个变量，然后让系统读取用户选择的结果。这是我的脚本结构（作为示例）：

CHOOSEfruit () {
clear
echo "Choose fruit you need to buy (a.Apple b.Banana c.Pear d.Pineapple)"
read FRUIT
case $FRUIT in
    a|A)
    echo "Apple"
    ;;
    b|B)
    echo "Banana"
    ;;
    c|C)
    echo "Pear"
    ;;
    d|D)
    echo "Pineapple"
    ;;
esac
clear
echo "The fruit you need to buy is $FRUIT"
echo ""
read -p "Press [Enter] key to go back to main menu"
clear
}

如果我选择“a”，我希望我的脚本输出：“您需要购买的水果是苹果”

答案1

通过循环可以更好地解决这个问题select：

PS3='Please select fruit from the menu: '

select fruit in 'No fruit please' Apple Banana Pear Pineapple; do
    case $REPLY in
        1)
            # User wants no fruit
            unset fruit
            break
            ;;
        [2-5])
            # All ok, exit loop
            break
            ;;
        *)
            # Invalid choice
            echo 'Try again' >&2
    esac
done

if [ -n "$fruit" ]; then
    printf 'The fruit you need is %s\n' "$fruit"
else
    echo 'You selected no fruit!'
fi

该select循环在交互式菜单中向用户呈现选项列表。向用户提供从菜单中选择项目的提示是 中的字符串$PS3。

在循环体中select， in 的值$fruit将是用户选择的实际文本字符串，而$REPLY将是用户在提示符下键入的任何内容。

请注意，无需case ... esac在循环中使用语句。您可以在这里使用任何代码。例如，您可能会觉得使用更舒服if ... then ... elif ... else ... fi：

if [ "$REPLY" = 1 ]; then
    unset fruit
    break
elif [[ $REPLY == [2-5] ]]; then
    break
else
    echo 'Try again' >&2
fi

与任何其他无限循环一样，select使用 退出循环。break

运行该代码三次：

$ bash script
1) No fruit please
2) Apple
3) Banana
4) Pear
5) Pineapple
Please select fruit from the menu: 1
You selected no fruit!

$ bash script
1) No fruit please
2) Apple
3) Banana
4) Pear
5) Pineapple
Please select fruit from the menu: 2
The fruit you need is Apple

$ bash script
1) No fruit please
2) Apple
3) Banana
4) Pear
5) Pineapple
Please select fruit from the menu: 6
Try again
Please select fruit from the menu: 3
The fruit you need is Banana

答案2

你几乎做对了。只需像这样编辑您的案例陈述：

case $FRUIT in
    a|A)
    FRUIT="Apple"
    ;;
    b|B)
    FRUIT="Banana"
    ;;
    c|C)
    FRUIT="Pear"
    ;;
    d|D)
    FRUIT="Pineapple"
    ;;
esac

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