macos - zsh - 使用默认值读取用户输入 - 空输入不为空？

Question

我写了一个像这样要求用户输入的函数:

function is_confirmed {

    read -rs -k 1 ans

    if [[ "${ans}" == "n" || "${ans}" == "N" ]]; then
        printf "No\n"
        return 1
    fi

    if [[ "${ans}" == "y" || "${ans}" == "Y" ]]; then
        printf "Yes\n"
        return 0
    fi

    # here is my actual problem!!! this doesnt work when user input is blank!
    if [[ "${ans}" == "" ]]; then
        printf "Yes!\n"
        return 1
    fi

    # Output is Damn!
    printf "Damn"
    return 1
}

到目前为止效果很好，但是，我想将"is"设置为默认回答，所以当用户什么都不输入并按下回车键时，它应该回退到"is"，所以我尝试了 || "$ans"== "" 但仍然会回到 "Damn"

怎么会呢？当我在函数末尾 echo $ans 时，它是空的...

编辑 1:

是这样的:

e_ask "Are you sure you want to install?\nWarning: This may override some files in your home directory."

if is_confirmed; then
    echo "Great!"
else
    e_error "Aborting..."
fi

函数如下:

function e_ask {
    printf "\n$1\n"
    printf "(Y/n): "
}

function e_warn {
    printf "Warning: $1\n"
}

function e_error {
    printf "Error: $1\n"
    exit 1
}

Answer 1

A case当您想考虑许多不同的值和一个默认值时会更好

function is_confirmed {    read -rs -k 1 ans    case "${ans}" in    y|Y|$'\n')        printf "Yes\n"            return 0        ;;    *)  # This is the default        printf "No\n"            return 1    esac}