Understanding the Difference Between Computer Directives and Commands (理解计算机指令和命令的区别)

In the realm（领域） of computer programming, the terms（措辞、术语） ‘directives’ and ‘commands’ are commonly（常常、通常） used. While they might appear synonymous（同义的） to the untrained（未经训练的） eye, these two concepts play（扮演） distinct（不同的） roles in the broader landscape of programming languages and systems operation. This article aims to unpack（解读） these concepts, providing a clear understanding of their differences, how they function, and their respective（各自的） roles in programming and system operations.
在计算机编程领域中，'指令’和’命令’这两个术语常常被使用。虽然对于未经训练的眼睛，它们可能看起来是同义词，但这两个概念在编程语言和系统操作的更广泛的景观中扮演着不同的角色。本文旨在解读这些概念，提供关于它们的差异、功能以及在编程和系统操作中的各自角色的清晰理解。

Exploring Computer Directives (探索计算机指令)

Overview (概述)

Computer directives, often simply referred（简称） to as ‘directives’, are statements（陈述、说明、声明） within a program that instruct the compiler or interpreter on how to process code. They play an integral（完整的） role in shaping the behavior of the compiler or interpreter, essentially（本质上） guiding it through the compilation or interpretation process.
计算机指令，通常简单地被称为’指令’，是程序中的语句，它指导编译器或解释器如何处理代码。它们在塑造编译器或解释器的行为中起着关键的作用，本质上引导着它通过编译或解释过程。

“Within a program"和"in a program” 在这个上下文中其实是可以互换的，两者的意思非常接近。然而，在英语中，"within"有时会被用来强调某物是在一个整体或系统的内部。在这里，"within a program"就是在强调指令是程序内部的一部分，而不只是在程序中存在。

所以，“Computer directives, often simply referred to as ‘directives’, are statements within a program that instruct the compiler or interpreter on how to process code.”
这句话的翻译可以是：“计算机指令，通常简称为’指令’，是程序内部的声明，它指导编译器或解释器如何处理代码。”

Role in Programming Languages (在编程语言中的角色)

Different programming languages have different ways of using directives. For instance, Python scripts typically begin with a shebang（[ʃɪˈbæŋ]） directive (#!/usr/bin/env python3), which informs（告知） the system about the interpreter to be used for executing the script.
不同的编程语言使用指令的方式各不相同。例如，Python脚本通常以shebang指令（#!/usr/bin/env python3）开始，该指令告知系统执行脚本时应使用哪种解释器。

#!/usr/bin/env python3print("Hello, World!")

In the case of C++, preprocessor（预处理） directives like #include and #define are used. These directives guide the compiler in handling the inclusion of header files and macro definitions, respectively.
对于C++来说，像#include和#define这样的预处理指令被使用。这些指令分别引导编译器处理头文件的包含和宏定义。

在口语中，#include 读作 “hash include” 或 “pound include”，而 #define 读作 “hash define” 或 “pound define”。这里的 “hash” 或 “pound” 指的就是井号（#）。

#include <iostream>
#define PI 3.14159int main() {std::cout << "The value of PI is: " << PI;return 0;
}

It’s crucial（关键的） to note that directives are not executed during runtime but during the parsing or compilation phase of the code.
需要特别注意的是，指令不是在运行时执行，而是在代码的解析或编译阶段执行。

Exploring Computer Commands (探索计算机命令)

Overview (概述)

Computer commands, or simply ‘commands’, are statements executed in a command-line environment such as a Unix/Linux shell. These commands directly interact with the system, enabling users to perform（执行） various operations.
计算机命令，或简称为’命令’，是在如Unix/Linux shell等命令行环境中执行的语句。这些命令直接与系统交互，使用户能够进行各种操作。

Role in System Operations (在系统操作中的角色)

Commands come in many forms, depending on the operating system and the shell being used. In Unix/Linux systems, commands such as ls, cd, mkdir are commonly used for listing directory contents, changing the current directory, and creating a new directory, respectively.
命令的形式多样，取决于正在使用的操作系统和shell。在Unix/Linux系统中，命令如ls、cd、mkdir常用于列出目录内容、更改当前目录和创建新目录。

在英语中，斜线 “/” 通常被读作 “slash”。所以，“Unix/Linux” 可以读作 “Yoo-niks slash Lin-ux” 或者 “Yoo-niks slash Lie-nux”。

$ ls         # List directory contents
$ cd /home   # Change to home directory
$ mkdir new_folder  # Create a new directory named 'new_folder'

Unlike directives, commands are interpreted and executed at runtime. They are sent to the system by users or programs to carry out（执行） specific tasks or operations.
与指令不同，命令在运行时被解释和执行。它们由用户或程序发送到系统，以执行特定的任务或操作。

Conclusion (结论)

While both directives and commands play pivotal（核心的） roles in the realm of computing, they serve different purposes. Directives are more about shaping how code is parsed or compiled, providing critical instructions that affect the structure and behavior of a program. On the other hand, commands are about controlling the system’s operation, allowing users to perform tasks and manipulate the system environment directly. By understanding these differences, programmers can better utilize these tools and navigate the world of programming and system operation with greater ease and efficiency.
虽然指令和命令都在计算领域中起着关键的作用，但它们有不同的目标。指令更多的是塑造代码如何被解析或编译，提供影响程序结构和行为的关键指令。另一方面，命令则是控制系统的操作，允许用户直接执行任务和操作系统环境。通过理解这些差异，程序员可以更好地利用这些工具，并以更大的轻松性和效率导航编程和系统操作的世界。