linux - 测试返回值 : command not found

Question

我编写了一个函数来将是或否的答案转换为真或假(0 或 1)。但是，每次运行我的脚本时，我都会收到“找不到命令”错误。请帮我解决问题

get_boolean(){
    #==============================================================================================
    # Returns false if the first argument is NO and returns true if it is YES.
    # If the first argument is not a valid YES or NO,
    # then the return value depends on the default specified by argument 2 (Default value)
    #==============================================================================================

    if [ "$1" == 'NO' ] || [ "$1" == 'no' ] || [ "$1" == 'No' ] || [ "$1" == 'N' ] || [ "$1" == 'n' ]; then
            return 1;
    elif [ "$1" == 'YES' ] || [ "$1" == 'yes' ] || [ "$1" == 'Yes' ] || [ "$1" == 'Y' ] || [ "$1" == 'y' ]; then
            return 0;
    elif [ "$2" == 'NO' ] || [ "$2" == 'no' ] || [ "$2" == 'No' ] || [ "$2" == 'N' ] || [ "$2" == 'n' ]; then
            return 1;
    elif [ "$2" == 'YES' ] || [ "$2" == 'yes' ] || [ "$2" == 'Yes' ] || [ "$2" == 'Y' ] || [ "$2" == 'y' ]; then
            return 0;
    fi
}

read -p 'Do you want to drop the table of invalids? [n]:' DROP_TABLE_OF_INVALIDS
echo "After read: $DROP_TABLE_OF_INVALIDS"
DROP_TABLE_OF_INVALIDS=get_boolean "$DROP_TABLE_OF_INVALIDS" 'n'
echo "After assignment: $DROP_TABLE_OF_INVALIDS"
if $DROP_TABLE_OF_INVALIDS; then
        echo "Hello. I will drop the table"
fi

当我运行脚本时，出现以下错误:

bash-3.2$ sh test.sh
Do you want to drop the table of invalids? [n]:y
After read: y
test.sh: line 24: y: command not found
After assignment: y
test.sh: line 26: y: command not found
bash-3.2$ sh test.sh
Do you want to drop the table of invalids? [n]:n
After read: n
test.sh: line 24: n: command not found
After assignment: n
test.sh: line 26: n: command not found

更新:下面的代码有效(感谢 Barmar!)

get_boolean(){
        #==============================================================================================
        # Outputs false if the first argument is NO and outputs true if it is YES.
        # If the first argument is not a valid YES or NO,
        # then the output value depends on the default specified by argument 2 (Default value)
        #==============================================================================================

        if [ "$1" == 'NO' ] || [ "$1" == 'no' ] || [ "$1" == 'No' ] || [ "$1" == 'N' ] || [ "$1" == 'n' ]; then
                        echo false;
        elif [ "$1" == 'YES' ] || [ "$1" == 'yes' ] || [ "$1" == 'Yes' ] || [ "$1" == 'Y' ] || [ "$1" == 'y' ]; then
                        echo true;
        elif [ "$2" == 'NO' ] || [ "$2" == 'no' ] || [ "$2" == 'No' ] || [ "$2" == 'N' ] || [ "$2" == 'n' ]; then
                        echo false;
        elif [ "$2" == 'YES' ] || [ "$2" == 'yes' ] || [ "$2" == 'Yes' ] || [ "$2" == 'Y' ] || [ "$2" == 'y' ]; then
                        echo true;
        fi
}

read -p 'Do you want to drop the table of invalids? [n]:' DROP_TABLE_OF_INVALIDS
echo "After read: $DROP_TABLE_OF_INVALIDS"
DROP_TABLE_OF_INVALIDS=$(get_boolean "$DROP_TABLE_OF_INVALIDS" 'n')
echo "After assignment: $DROP_TABLE_OF_INVALIDS"
if $DROP_TABLE_OF_INVALIDS; then
                echo "Hello. I will drop the table"
fi

以下是使其生效的编辑:

• 函数“回显”而不是返回。
• 输出值为 bash true 或 false(用于在 if 中进行测试，否则得到 0:未找到命令或 1:未找到命令)
• 函数调用包含在“$(”和“)”中

Answer 1

语法:

DROP_TABLE_OF_INVALIDS=get_boolean "$DROP_TABLE_OF_INVALIDS" 'n'

表示在执行命令`"$DROP_TABLE_OF_INVALIDS"'n'"时设置环境变量DROP_TABLE_OF_INVALIDS为字符串"get_boolean"。

用函数的输出赋值给变量的方法是:

DROP_TABLE_OF_INVALIDS=$(get_boolean "$DROP_TABLE_OF_INVALIDS" 'n')

此外，您需要更改函数以使用 echo 而不是 return。 return 设置退出状态，而不是函数的输出。